JPH0372620A - Formation of polycrystalline semiconductor film by microwave plasma cvd method - Google Patents

Abstract

PURPOSE:To form a polycrystalline semiconductor film of good quality on an insulative substrate by a method wherein a film-forming device by a microwave plasma CVD method is used, the insulative substrate is placed on a conductive susceptor and a film formation is performed while a specified high-frequency voltage is applied between a perforated grid electrode and the susceptor. CONSTITUTION:A plasma producing chamber 701 and a film-forming chamber 712 are insulated from each other by an insulator 712. A microwave generated by a microwave oscillator is transmitted through a waveguide 704, introduced in the chamber 701 through a microwave introducing window 703 and raw gas introduced in the chamber 701 through gas introducing tubes 705 and 706 is brought into a plasma state. At this time, it is desirable to apply a magnetic field to the chamber 701 by a magnetic field generating device 709. Thereby discharge is stabilized and high-density plasma is efficiently generated. ions in the plasma produced in the chamber 701 are controlled in their energy and led out by a high-frequency voltage applied between a grid electrode 711 and a conductive susceptor 708 and a thin film is formed on an insulative substrate 713 on the susceptor 708. As the high-frequency voltage, a high-frequency voltage of 20 to 500MHz is desirable and it is desirable to control the voltage in 100 to 500V.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method of forming a high quality polycrystalline semiconductor film by microwave plasma CVD using an easily available insulating substrate. More specifically, the present invention generates plasma by decomposing a raw material gas using microwave energy in a plasma generation chamber, introduces the plasma into a film forming chamber, and generates plasma on a support table installed in the film forming chamber. When forming a polycrystalline semiconductor film on an insulating substrate placed on an insulating substrate, a high-frequency voltage of a specific frequency is applied between the plasma generation chamber and the support base to increase the amount of plasma in the vicinity of the surface of the substrate. The present invention relates to a method for forming a high-quality polycrystalline semiconductor film on the insulating substrate by performing film formation while controlling the energy dispersion of ions.

[Description of prior art]

Recently, liquid crystal displays have attracted attention as an alternative to cathode ray tubes because they are thin and consume little power. For this reason, from the viewpoint of improving the performance of liquid crystal displays, research on polycrystalline silicon thin film transistors (hereinafter referred to as "polycrystalline silicon TPT") is being actively conducted. Polycrystalline silicon TPT
The focus of this research is on how to efficiently form high-quality polycrystalline semiconductor films at low temperatures on the surface of easily available insulating substrates such as glass. However, at present, an appropriate method that enables efficient formation of a high-quality polycrystalline semiconductor film on the above-mentioned insulating substrate has not yet been realized.

- By the way, polycrystalline silicon semiconductor films are formed using the plasma CVD method (
plasma chemical vapor dep
A number of proposals have been made regarding the position method.

Such a plasma CVD method is called an RF glow discharge decomposition method that uses radio frequency (RF) power, and in this method, a raw material gas is decomposed by radio frequency (RF) discharge to form a polycrystalline semiconductor film on the surface of the substrate. However, the RF glow discharge decomposition method has the problem that the raw material gas utilization efficiency is not satisfactory, and there are several rules and membrane parameters that are organically related to each other. do,
There is a problem in that it is difficult to control such a plurality of parameters as desired, and it is difficult to stably, constantly and efficiently obtain a desired polycrystalline semiconductor film.

For these reasons, recently, microwave plasma CVD, which uses microwave power with a short wavelength instead of high-frequency power, has been developed.
The law is attracting attention. The microwave plasma CVD method has the advantage that a deposited film can be formed at a high deposition rate because plasma can be generated at a high density compared to the RF glow discharge decomposition method.

However, the microwave plasma CVD method is similar to the RF glow discharge decomposition method described above, and there are several film-forming parameters that are organically related to each other, and it is difficult to control these parameters as desired. Therefore, there is a problem that it is difficult to consistently obtain a desired polycrystalline semiconductor film.

From the viewpoint of improving these problems of the microwave plasma CVD method, a film formation method that applies a magnetic field in the microwave CVD method, that is, ECR (Electron Cyclotron Resonance) has been developed.
A plasma CVD method has been proposed.

According to this ECR plasma CVD method, it is said that a high quality polycrystalline semiconductor film with fewer defects can be obtained with higher efficiency and a higher deposition rate than when using the microwave plasma CVD method. By the way, in this ECR plasma CVD method, in order to obtain a high-quality polycrystalline semiconductor film, it is necessary to set conditions for controlling the ion energy in the plasma generated by applying a magnetic field in addition to the conditions related to plasma generation. However, there is a problem in that it is technically difficult to bring these conditions into a desirable state through organic interrelationships.

For these reasons, it is difficult to consistently obtain a high-quality polycrystalline semiconductor film that exhibits desired characteristics as a constituent material of a semiconductor device at low temperatures using any of the film-forming methods that have been proposed so far.

By the way, regarding the film forming method using the ECR plasma CVD method, a method using an apparatus having a schematic configuration shown in FIG. 6 has been reported in Proceedings of the Japan Society of Applied Physics 31pK-2.

In this report, using an apparatus with the configuration schematically shown in Figure 6, it was possible to form a polycrystalline silicon film at a low temperature of 200°C on a single-crystal silicon wafer by homoepitaxial growth at 400°C. It is said that The device shown in FIG. 6 is an ECR plasma device equipped with a DC power source for ion control. In FIG. 6, 600 is a DC power source for ion control, 601 is a plasma generation chamber, 602 is a deposition chamber,
03 is a microwave introduction window, 604 is a microwave waveguide,
605 is a gas introduction tube, 607 is a plasma flow, 60B is a conductive sample stage, 609 is a magnetic field generator, 610 is a water cooling pipe, 611 is a grid electrode for applying an electric field, 612 is an insulator,
613 is a substrate.

In this report, in the deposition apparatus having the configuration shown in FIG.
13 is made of single crystal silicon, silane (SiHa) gas is flowed from the gas introduction pipe 605, the pressure is adjusted to 10-' Torr, and the substrate temperature is 200° C. between the grid electrode 611 for applying an electric field and the conductive sample stage 608. When forming a film by applying a DC electric field to cause an ECR type microwave discharge,
It is said that a polycrystalline silicon film can be obtained on a single-crystal silicon substrate.

However, the present inventors actually attempted to deposit a silicon thin film on a Corning #7059 glass substrate at a substrate temperature of 400° C. using the same method described above, but a good polycrystalline film could not be obtained. One of the reasons why good polycrystals could not be obtained
One possible reason is that because the substrate was an insulator, voltage could not be effectively applied between the voltage application grid electrode and the substrate. Of course, lattice matching could not be achieved because the substrate was not single-crystal silicon.

As described above, by any known plasma CVD method, a large-area, high-quality polycrystalline semiconductor film that can be used for TPT, for example, can be formed stably and with good reproducibility on an insulating substrate such as a glass substrate. It is difficult to do so.

By the way, a T having a polycrystalline silicon film semiconductor layer used in an active matrix type liquid crystal display
PT (hereinafter referred to as "active matrix polycrystalline silicon TPT") has been proposed.

This active matrix polycrystalline silicon TPT is generally manufactured by the following procedure.

For example, a transparent electrode made of ITO is formed on an expensive insulating transparent substrate such as a quartz glass substrate, and then
A polycrystalline silicon film serving as a semiconductor layer is formed on this transparent electrode.

The polycrystalline silicon film is processed by LP-CVD, which is conventionally considered to be effective for forming high-quality polycrystalline silicon films.
low pressure chemical
When attempting to form the film using the apordeposition method, silane gas is used as a source gas and a film deposition temperature of 700° C. or higher is employed.

Therefore, in the film forming process, when the silane gas is decomposed and hydrogen radicals are generated, the hydrogen radicals inevitably reach the ITO film which is kept at a high temperature, and oxygen It often reacts chemically with atoms, resulting in the 0 ITO film becoming opaque and no longer functioning as a transparent electrode.

For these reasons, with the LP-CVD method, it is difficult to regularly and stably obtain a polycrystalline silicon film for forming a desired active matrix polycrystalline silicon TFT.

Furthermore, in the case of the above LP-CVD method, the film deposition temperature is as high as 700°C or higher, so materials with low heat resistance such as practical glass plates and synthetic resin films cannot be used for the substrate. . Therefore, the above LP
-Even if it is possible to obtain a polycrystalline silicon film for forming an active matrix polycrystalline silicon TFT that is suitable for use by the CVD method, it will be quite expensive in any case. Separately, a polycrystalline silicon film as a semiconductor layer is insulated by molecular beam evaporation using single crystal silicon or polycrystalline silicon as a deposition source under an ultra-high vacuum of about 10-” Torr at a film deposition temperature of about 400°C. There is a proposal to fabricate an active matrix polycrystalline silicon TPT by forming the active matrix polycrystalline silicon TPT on a 0N1 transparent substrate.
The 0FF current ratio is about 103 to 104, and the carrier mobility is about 2 to 10 cd/V・S, making it impractical (December 1, 1983).
Published by Ohmsha Co., Ltd., 11 Membrane Handbook No. 62
(See page 5).

[Purpose of the invention]

The main object of the present invention is to use an apparatus having a plasma generation chamber and a film formation chamber, to transport plasma generated in the plasma generation chamber to the film formation chamber, and to transfer the plasma generated in the plasma generation chamber to the film formation chamber so that the surface of a substrate placed in the film formation chamber can be Microwave plasma solves the above-mentioned problems in the conventional film-forming method, and enables efficient production of high-quality polycrystalline semiconductor films suitable as constituent materials for electronic devices such as various semiconductor devices. An object of the present invention is to provide an improved film forming method using the CVD method.

Another object of the present invention is to generate plasma by bringing microwave energy into contact with a source gas in a plasma generation chamber, and transporting the generated plasma to a deposition chamber through a grid electrode without applying a high-frequency voltage. (2) Forming a polycrystalline semiconductor film on the surface of the insulating substrate placed on the substrate mounting table by forming a film without applying a high frequency voltage to the substrate mounting table arranged in the film forming chamber. The purpose is to provide a method.

Still another object of the present invention is to generate plasma by bringing microwave energy into contact with source gas in a plasma generation chamber,
The generated plasma is introduced into a film forming chamber in which a substrate mounting table is installed via a grid electrode, and at this time, a high frequency voltage of a predetermined frequency is applied between the grid electrode and the substrate mounting table to generate ion energy. The object of the present invention is to provide a method for controlling the dispersion of ion energy and forming a high-quality polycrystalline semiconductor film on an insulating substrate at low temperatures.

[Structure and effects of the invention]

The present inventors have developed the above-mentioned conventional microwave plasma CV
In order to solve the various problems in the method of forming a polycrystalline film by the D method or the ECR plasma CVD method and to achieve the above object, studies were conducted through the experiments described below. That is, the experiments described below were conducted with a view to forming a high-quality polycrystalline semiconductor film on the surface of an easily available and inexpensive insulating substrate such as glass. As a result, a plasma is produced by bringing the raw material gas into contact with microwave energy in a plasma generation chamber, and the generated plasma is introduced into a film formation chamber and applied onto an insulating substrate placed within the film formation chamber. When forming a deposited film, the insulating substrate is placed on a conductive support, and the film is formed without applying a high frequency voltage of a specific value between the plasma generation chamber and the support. When performing this, the ions incident on the insulating substrate are controlled to be in a preferable state with a small energy dispersion width, and a desirable ion profile is formed near the surface of the insulating substrate. We obtained the knowledge that a high-quality polycrystalline semiconductor film can be formed on the surface even when using a polycrystalline semiconductor film. The present inventors also discovered that in the above case, when a magnetic field is applied to the plasma generation chamber, the density of ions with a small energy dispersion increases near the surface of the insulating substrate,
It was found that a very favorable ion profile was formed and a high-quality polycrystalline semiconductor film was formed on the 34 insulating substrate.

The present invention was completed as a result of further research based on these findings obtained through experiments. The present invention includes two aspects described below.

One aspect of the present invention is the microwave plasma C described below.
A method for forming a polycrystalline semiconductor film (semiconductor film) using a VD method.

That is, a film forming apparatus using a microwave plasma CVD method having a plasma generation chamber and a film formation chamber equipped with a microwave introduction means is used, a raw material gas is introduced into the plasma generation chamber, and at the same time the microwave introduction means is introduced. Microwave energy is injected into the plasma generation chamber through the plasma generating chamber to cause discharge to decompose the raw material gas and generate plasma, and a multi-perforated hole provided between the plasma generation chamber and the film forming chamber. A method for forming a deposited film on the surface of an insulating substrate placed on a conductive support set in the film forming chamber by causing the plasma to flow into the film forming chamber through a green electrode, the method comprising: A method for forming a high-quality polycrystalline semiconductor film, characterized in that the deposited film 5 is formed while applying a high frequency voltage of 20 to 500 MHz between the green electrode and the conductive support.

Another aspect of the present invention is the microwave plasma CV as described below.
A method for forming a polycrystalline semiconductor film by method D.

That is, a microwave plasma C having a plasma generation chamber and a film forming chamber equipped with a microwave introduction means and a magnetic field generation means.
Using a film forming apparatus based on the VD method, a magnetic field is applied to the plasma generation chamber by the magnetic field generation means, raw material gas is introduced, and at the same time microwave energy is applied to the plasma generation chamber via the microwave introduction means. The raw material gas is decomposed to generate plasma by generating a discharge, and the plasma is introduced into the film forming chamber through a multi-perforated grid electrode provided between the plasma generating chamber and the film forming chamber. A method for forming a deposited film on the surface of an insulating substrate placed on a conductive support set in the film forming chamber, the method comprising: A method for forming a high quality polycrystalline semiconductor film, the method comprising: applying a high frequency voltage of 20 to 500 MHz between the film and the conductive support.

According to the present invention, the temperature of the substrate during film formation is lowered to 700°C as in the conventional CVD method for forming a polycrystalline semiconductor film.
There is no need to maintain the film at a high temperature of 400°C or higher, and it is possible to form a high-quality polycrystalline semiconductor film by keeping it at a much lower temperature of 400°C or lower, and without raising the internal pressure to an ultra-high vacuum during film formation. It is possible to form a homogeneous film with a uniform thickness on a large area substrate. Further, according to the present invention, as mentioned above, there is no need to hold the substrate at a high temperature during film formation, so that impurities in the substrate are not released and trapped in the polycrystalline semiconductor film that is formed. do not have. Therefore, according to the present invention, practical glass (soda-lime glass, soda-lime glass),
A high-quality polycrystalline semiconductor film can be formed using an easily available and inexpensive material such as a synthetic resin film for the substrate. Therefore, the present invention makes it possible to provide at low cost a semiconductor device such as a TPT (Fil film transistor) or a photoelectric conversion element such as a solar cell, which uses a polycrystalline semiconductor film as a constituent material.

In particular, according to the present invention, it is possible to provide a desirable polycrystalline silicon TPT for use in an active matrix liquid crystal display (i.e., the above-mentioned active matrix polycrystalline silicon TPT), which has been difficult to realize in the past. .

That is, according to the present invention, an easily available and inexpensive insulating transparent member is used as a base, a polycrystalline silicon film serving as a semiconductor layer is formed on the base, and an active matrix polycrystalline silicon TPT is formed. When fabricating an active matrix polycrystalline silicon TPT, the resulting active matrix polysilicon TPT exhibits a desirable 0N10 F
It is desirable to exhibit carrier mobility of cn/V −S or higher.

The experiments conducted by the present inventors will be described below7. When forming a deposited film on an insulating substrate placed in the chamber, the substrate is placed on a support made of a conductive member, and the plasma generation chamber and the support are connected. When a high frequency voltage was applied between the two electrodes, the state of the ion energy profile near the surface of the insulating substrate was observed. The above observation was performed by changing the frequency of the applied high-frequency voltage. Also,
In this experiment, we observed the dependence of the applied high-frequency voltage on the frequency.

To carry out this experiment, an apparatus having the configuration schematically shown in FIG. 1(A) was used.

In Fig. 1 (A), 100 is a variable oscillation frequency high-frequency power supply, 101 is a capacitor, 102 is a DC power supply for applying a negative voltage, and 103 is an electrode for ion energy control 9 whose center part is processed into a mesoche shape. , 104 is an ion-reflecting green electrode with a mesoche-like process in the center, 105 is an ion-collecting electrode,
106 is a DC power supply for applying voltage for electron blocking, 107 is an insulating plate with a small hole in the center, 108 is a microammeter, 109 is an insulator, 110 is a grounding electrode, 111 is a plasma generation chamber, 112 is an electromagnet, 113 is a helical antenna for introducing microwaves, 114 is a microwave waveguide, 115 is a vacuum container, 116 is a gas introduction tube, 117 is a plasma flow, 118
．． 119 is a tuner, and 120 is a coaxial type vacuum glass.

In the apparatus shown in FIG. 1A, microwaves are introduced from a helical antenna 113 connected to a microwave waveguide 114 to generate plasma.

The plasma generation chamber 111 and the ion energy measurement section are separated by a grounding electrode 110.

The ion energy measuring section mainly includes the ion collecting electrode 10.
5. Glynode electrode for ion reflection 104, microcurrent meter 10
8. It is composed of a DC power supply 106 for applying an electron blocking voltage. The ion reflecting grid electrode 104 is used to guide high energy ions of a certain value to the ion collection electrode 105 and reflect other low energy ions. The ion collecting electrode 105 is used to collect ions that have passed through the ion reflecting green electrode 104. A high frequency voltage is applied to the insulating plate 107 and the plasma generation chamber 111 from the variable oscillation frequency high frequency power source 100 via the ion energy control electrode 103 and the grounding electrode 110.

The electromagnet 112 is for stabilizing the microwave discharge and making plasma generation more efficient.

First, after thoroughly evacuating the inside of the plasma generation chamber 111 and the vacuum container 115 using an evacuation device (not shown), H2 gas as a raw material gas is introduced through the gas introduction pipe 116 for 4 seconds.
ecm into the plasma generation chamber 111, and the inside of the vacuum vessel 115 is controlled at a pressure controller (not shown) to control the
The pressure was controlled at Torr. Immediately, after energizing the electromagnet 112 and generating a magnetic field within the plasma generation chamber 111,
A microwave power of 100 W was input into the plasma generation chamber 111 from a microwave power source (not shown) through the waveguide 114 and the helical antenna 113, and the H2 gas as the gaseous substance was turned into plasma in the magnetic field. Next, the potential of the ion collecting electrode 105 is set to -50V, and the grid electrode 1
04 and the high frequency peak-to-peak voltage V,p applied to the ion energy control electrode 103.
is changed, and the ion collecting electrode 1 is measured by the microcurrent meter 108.
The ion current flowing into the grid electrode was measured, and the ion energy profile was calculated from the ion current value and the voltage value applied to the grid electrode.

The frequencies of the high frequency waves applied to the ion energy control electrode 103 are 40.7 MHz and 13.56 MHz.

The ion profiles measured when setting the frequency to 25MHz and 20MHz are shown in Figure 2 (A) and Figure 2 (B), respectively.
2(C) and 2(D).

From the results shown in Figure 2 (A), Figure 2 (B), Figure 2 (C), and Figure 1 2 (D), the following was found. did. As the frequency of the applied high-frequency voltage increases, the energy peak of the ions becomes sharper. Second (A
) and Figure 2(B), when the frequency of the applied high frequency is 13.56 MHz, the dispersion of the measured ion energy is large, and in particular, the peak to peak voltage Vl'-I of the applied high frequency is large. When ' is increased to 40V,
Multiple energy peaks appear, and the dispersion of ion energies becomes even larger. Imagining this, 40.7MH
In the case of z, the energy peak of the ion is sharp, and even when Vp, , p is 40V, the energy peak is single.

These facts indicate that when attempting to control the energy of ions incident on an insulating substrate by applying a high-frequency voltage to a conductive support in a thin film deposition process, it is possible to control the energy of ions by optimizing the frequency of the applied high-frequency voltage. This suggests that conditions can be set where the energy peak is single and the ion energy peak is sharp. This means that the dispersion of ions resulting from side reactions in the deposition reaction is suppressed.

In this experiment, we investigated the effect of a magnetic field on the energy profile of ions incident on an insulating substrate. In this experiment, the apparatus shown in FIG. 1(B) was used in addition to the apparatus shown in FIG. 1(A). The basic configurations of the devices shown in FIG. 1(A) and FIG. 1(B) are the same; the difference is that in FIG. 1(B), the ion energy measurement unit This point is located perpendicular to the direction of the magnetic field generated by the electromagnet. In Figure 1 (B), the same components as in Figure 1 (A>) are indicated by the same symbols. In this experiment, two experiments were conducted.

First, the energy profile of ions incident perpendicular to the magnetic field was measured in the same manner as in Experiment 1 using the apparatus shown in FIG. 1(B). As for the measurement results, in Experiment 1, the effect of high frequency voltage application was not noticeable.

Next, in the apparatuses shown in Figures 1(A) and 1(B), we applied a high-frequency voltage with a frequency of 40.7 MHz in the same manner as in Experiment 1 without applying a magnetic field. The ion energy profile is measured and the second (E
) and Fig. 2(F).

Discussion based on the results of Experiment 2 The fact that in Experiment 2, when a high-frequency voltage was applied in the direction perpendicular to the magnetic field, no significant effect appeared compared to Experiment 1 is that
It is explained as follows. That is, the ion control electrode 103
Assuming that the electric field applied to is E and the magnetic flux density is B, when the ion current measurement section is parallel to the central axis of the plasma flow 117, the electric field E and the magnetic field are perpendicular to each other, and the charged particles drift EXE.

In other words, it drifts in a direction parallel to the ion energy control electrode, which is perpendicular to the electric and magnetic fields. For this reason, it can be explained that when the ion current measuring section was arranged parallel to the magnetic field (the central axis of the plasma flow), the effect of applying the electric field was smaller than when it was arranged perpendicularly.

Comparison of Figure 2 (E) and Figure 2 (F) shows that there is almost no difference between the energy profile of ions incident parallel to the plasma flow and the energy profile of ions incident perpendicularly to the plasma flow. The effect of the frequency was observed in the same way as when a magnetic field was applied.From these results, the following was clarified.

That is, (i) when a magnetic field exists, it is more effective to apply a high-frequency voltage in the direction perpendicular to the magnetic field to control the energy of ions; (ii) when no m field exists, (iii) When performing plasma treatment by controlling ion energy, it is more preferable to place the sample perpendicular to the direction of the magnetic field in a magnetic field.

In the main experiment 3, we investigated in which frequency range the application of high-frequency voltage to control the energy dispersion of ions is effective.

Using the ion energy measuring device shown in FIG. The peak value of ion energy E when changing variously
Half width of ion energy ΔEH (
eV) and the applied frequency f
(MHz) and is shown in FIG. 2(G).

Based on Section 3, in Figure 2 (G), the frequency of the applied high-frequency voltage is 20
From around MHz, ΔEH/E drops sharply, indicating that the energy dispersion of ions becomes smaller. However, from Figure 2 (D) of Experiment 1, when V is large, the ion energy peak is not single at a frequency of 20 MHz. In Fig. 2(G), it was found that it is preferable to apply a high frequency voltage with a frequency of 25 MH2 or more that satisfies the relationship ΔEo/E, 4≦0.5.

In actual thin film deposition using microwave discharge, conditions must be stable for the discharge to yield a uniformly deposited film with good reproducibility. In Experiment 4, the frequency of the microwave for generating plasma was kept constant at 2.45 GHz, the voltage of the applied high-frequency voltage was kept constant, and the frequency was varied to examine the stability of discharge. Using the apparatus shown in Figure 1 (A), as a raw material gas for plasma generation,
Using H2 and a mixed gas of H2 and Ar, the flickering of the discharge, the reflected power of the microwave, the minimum power for maintaining the discharge, and the sharpness of the ion energy peak are controlled by the applied frequency of the high-frequency voltage for ion energy control. An evaluation was made regarding the As the frequency of the high-frequency voltage approached the 2.45 GHz frequency range of microwaves, the discharge became unstable, probably due to mutual interference, and the ion energy profile could no longer be measured stably. The evaluation results are shown in Table 1.

Discussion based on the 8+- results of Experiment 4 The results in Table 1 and - When the raw material gas for forming a deposited film is used for boat fishing, the discharge tends to be generally more stable than in the case of H2 or Ar. For some reason, H2 and Ar
Discharge stability can be evaluated by a discharge test using As a result of the evaluation, when the frequency of the microwave used for plasma generation is 2.45 GHz, the upper limit of the applied frequency of the high-frequency electric field for ion energy control is preferably a frequency that does not affect the microwave discharge, and is 500 MHz or less. It was found that it is desirable that it is, and more preferably that it is 100 MH'2 or less.

Linear consideration of acids 1 to 4 From the experimental results of Experiments 1 to 4, when H2 (H2 and Ar in Experiment 4) is used as the plasma generation gas, there is no interference with the 2.45 GHz microwave discharge. In order to control the energy dispersion of the ions in the plasma, the frequency of application of the high-frequency voltage to the suitable support is preferably between 20 MHz and 5 MHz.
00MHz, optimally 2'5MH2 to 100M
It turned out to be Hz.

In Experiments 1 to 4, in order to stably measure ion energy, H2 or Ar, which is a gas that does not form a deposited film on the ion collection electrode, was used. However, in actual thin film deposition, a raw material gas for forming the deposited film is used, so next, in the microwave plasma deposition method, Experiment 1
Further experiments were conducted to confirm the validity of the results obtained in Experiments 4 to 4.

Large dust Σ The present inventors used silane (SiH) as a raw material gas for deposition.
4) Using gas, generate plasma by microwave discharge at 2.45 GHz, apply a high frequency voltage between the plasma generation chamber and the conductive sample stage, and place it on the insulating substrate placed on the sample stage. An experiment was conducted to extract ions from the plasma to form a silicon thin film, and the effect of the frequency of the applied high-frequency voltage on the crystallinity was investigated. As an apparatus for conducting this deposition experiment, a microwave plasma deposition apparatus schematically shown in FIG. 7 was used. The device in Figure 7 is
DC power supply 600 for controlling ion energy of the device shown in FIG.
Instead, a variable frequency high frequency power source 7009 0 having an impedance matching circuit 714 is newly provided. In FIG. 7, 701 is a plasma generation chamber, 702 is a film formation chamber, 703 is a microwave introduction window, 704 is a microwave waveguide, 705 and 706 are gas introduction tubes, 707 is a plasma flow, and 708 is a conductive support ,7
09 is a magnetic field generator, 710 is a water cooling pipe, 711 is a green electrode, 712 is an insulator, and 713 is an insulating substrate.

The plasma generation chamber 701 and the film formation chamber 702 are insulated by an insulator 712. The microwave waveguide 704 is connected to a microwave oscillator (not shown), and the microwaves oscillated from the microwave oscillator are transmitted through the waveguide 704 and generate plasma through a microwave introduction window made of a material such as quartz. A gas introduction pipe 705 or 70 is introduced into the chamber.
The raw material gas introduced from step 6 is turned into plasma. At this time, when a magnetic field is applied to the plasma generation chamber by the magnetic field generator 709, the discharge is maintained stably due to the influence of the magnetic field, and high-density plasma can be efficiently generated.

The water cooling pipe 710 is provided to prevent the magnetic field generating device from heating and to stably generate a magnetic field. The ground electrode 711 is made of a highly conductive material in the form of a menosh, and is connected to the inner wall of the plasma generation chamber and grounded.

The high frequency voltage is generated from the high frequency type m7oo and is applied to the conductive support base 70B provided in the deposition chamber 709 via the matching circuit 714. Ions in the plasma generated in the plasma generation chamber 701 are extracted with energy controlled by a high frequency voltage applied between the grid electrode 711 and the conductive support 708, and form a thin film on the insulating substrate.

The conductive support 708 has a built-in heater (not shown), and can control the temperature of the insulating substrate placed on the conductive support.

In Experiment 5, a quartz glass substrate was used as the insulating substrate, the substrate temperature was controlled at 400°C, and the film forming chamber 702 was evacuated to a pressure of 10-7 Torr using a vacuum pump (not shown), and then the gas introduction tube was 705 for 4 s of SiH4 gas
ecm, and the deposition chamber was heated to 3 x 10-5 To
rr, a magnetic field is applied to the plasma generation chamber by the magnetic field generator 709, a high frequency voltage is applied from the high frequency 2 power source 700 to the conductive support base 708, and 300 W of microwave is applied to generate the plasma for a certain period of time. membrane was performed. The frequency of the high frequency voltage to be applied is 13.56MH
A silicon thin film was formed on a quartz glass substrate using the method described above by varying the applied voltage from Ov to 600V at 100 MHz, 40 MHz, and 100 MHz.

Regarding these silicon thin films, RHEED (Refl
active High Energy E Ie
Crystallinity was evaluated based on a pattern obtained by ctronD 1fraction (reflection high-speed electron diffraction).

RHEED observation was performed using a JEM-100SX model electron microscope manufactured by JEOL. The evaluation based on the observation results of RHEED is qualitatively shown in FIG. 3(A).

The RHEED pattern changes from a halo to a ring, spot, and streak pattern as the crystallinity of the deposited film approaches from amorphous to polycrystalline to single crystal.

Evaluation using the RHEED pattern was performed by classifying the halo pattern and streak pattern into approximately 10 levels.

The ○ marks in Figure 3 (A) are for the case where a DC voltage was applied for comparison.

Ta.

(1) Crystallization is easier when a high-frequency voltage is applied to the sample stage than when a DC voltage is applied, and reflecting the results of Experiment 1, the higher the frequency of the high-frequency voltage, the
Better crystallinity. Furthermore, the differences due to frequency also reflect the results of Experiment 3.

(2) If the high frequency voltage applied to the support is too high, the crystallinity decreases, probably due to large ion bombardment. The results show that an applied voltage in the range of 100 to 500 V is suitable for obtaining crystals on a quartz substrate, although this varies somewhat depending on conditions such as temperature and internal pressure.

In Experiment 6, in order to examine the effect of internal pressure on crystallization, in Experiment 5, the voltage applied to the conductive support was set to 200
The crystallinity of the silicon thin film formed by keeping V constant and changing the internal pressure of the film forming chamber is determined by RHE.
Evaluation was made by ED. In this case as well, the frequency of the high frequency voltage is set to 1
Experiments were conducted with the frequencies changed to 3.56 MHz, 40 MHz, and 100 MHz.

The operating procedure for the experiment was the same as in Experiment 5.

The results of the qualitative evaluation by RHEED are shown in Figure 3 (B).

Discussion based on the results of acid 6 From the results shown in Figure 3 (B), when applying a high frequency voltage to the sample stage and forming a silicon thin film on a quartz substrate under the experimental conditions of Experiment 6, the pressure is 5 X 10-3 Torr or less. It was found that crystallinity can be further improved by increasing the frequency of the applied high-frequency voltage. In experiment 6, I
Experiments have not been conducted at pressures below O-'Torr, because the gas density is too small to cause electrical discharge.

Otsuzumi 1 In Experiment 7, in order to examine the effect of substrate temperature on crystallization, in Experiment 5, the frequency of the high-frequency voltage applied to the sample stage was fixed at 40 MHz, and when the applied voltage was 200 V, the substrate temperature The crystallinity of the silicon thin film formed by changing the crystallinity was evaluated by RHEED, and the qualitative evaluation results are shown in Fig. 3 (C).

Furthermore, while the frequency of the high-frequency voltage remained at 40 MHz, the silicon thin film obtained by changing the substrate temperature by changing the applied voltage to 300 V was analyzed by X-ray diffraction, and the crystal grain size was determined to be 5 herr.
It was determined from the formula of er. A graph of crystal grain size versus substrate temperature is shown in FIG. 3(D).

Discussion based on the results of acid 7 From the results in Figures 3 (C) and 3 (D), it is clear that the substrate temperature is 20
It was revealed that crystallization occurred even in the range of 0° C. to 400° C., and the crystal grain size increased as the substrate temperature increased.

5. Comprehensive consideration of the results of experiments 5.6 and 7. To summarize the results of experiments 5.6 and 7, the raw material gas for thin film deposition is introduced into the plasma generation chamber, plasma is generated by microwave discharge, and plasma generation is performed. Even if a deposited film was actually formed by applying a high-frequency voltage between the chamber and the conductive support to draw out the ions in the plasma onto the insulating substrate placed on the conductive support, Experiment 1 to The results reflect the basic experimental results up to Experiment 4. That is, it has been found that when forming a polycrystalline thin film on an insulating substrate, a film with higher crystallinity can be obtained by applying a high frequency voltage to the sample stage rather than by applying a DC voltage. It was also confirmed that crystallinity was further increased in the range of 25 to 100 MHz by using a high frequency voltage.

It has also been newly discovered that the effect of applying a high-frequency voltage becomes noticeable when the internal pressure is below 5 x 10-'' Torr.Also, crystallization occurs at a substrate temperature of 200°C or above, and in order to improve crystallinity, The applied voltage of the high frequency voltage is 100 to 5.
It has been found that it is also important to control the voltage within the range of 00V.

From the results of Experiments 1 to 7 above, the following was found.

Plasma is generated in a plasma generation chamber using the raw material gas for deposited film formation by microwave discharge, and a high frequency of 20 to 500 MHz is generated between the green electrode provided at the exit of the plasma chamber and the conductive support provided in the deposition chamber. By applying a voltage, the energy dispersion of ions in the plasma is kept low, and the applied voltage is further controlled in the range of 100 to 500 V, and the pressure in the deposition chamber is set to 1 x 10-' to 5 x 10-T.
When a deposited film is formed under controlled conditions, a polycrystalline semiconductor thin film with good crystallinity is formed on an insulating substrate such as glass at a substrate temperature of 200 to 400°C. In addition, in order to stabilize microwave discharge and generate plasma with high efficiency, when applying a magnetic field in the plasma generation chamber, an insulating substrate is placed perpendicular to the direction of the magnetic field, and the high-frequency voltage is applied to the grid. The energy of ions incident on the insulating substrate can be more effectively controlled by applying it between the electrode and the conductive support.

The present invention has been completed based on the facts found from the results of the experiments described above, and the method for forming a 78 polycrystalline semiconductor film by the microwave plasma CVD method provided by the present invention is based on the following configuration. That is.

That is, a film forming apparatus having a plasma generation chamber and a film forming chamber equipped with a microwave introducing means is used, a raw material gas is introduced into the plasma generating chamber, and a source gas is introduced into the plasma generating chamber through the microwave introducing means. Injecting microwave energy to generate an electric discharge to decompose the raw material gas and generate plasma;
The plasma is injected into the film forming chamber through a multi-perforated grid electrode provided between the plasma generation chamber and the film forming chamber, and placed on a conductive support provided within the film forming chamber. A method for forming a deposited film on a surface of an insulating substrate, comprising: between the green electrode and the conductive support;
A polycrystalline semiconductor film is formed by applying a high frequency voltage preferably in the range of 20 to 500 MHz, more preferably in the range of 25 to 100 MHz, preferably in a controlled range of 100 to 500 MHz.

In the method of the present invention, a magnetic field may be applied to the plasma generation chamber by a magnetic field generating means in order to generate microwave discharge more stably and generate plasma with high efficiency. When the magnetic field extends to the surface of the insulating substrate, the conductive sample stage is installed so that the direction of the magnetic field and the direction of the electric field formed by applying the high-frequency voltage roughly match, and In order to make the application of the high frequency voltage more effective, it is desirable to arrange the surface of the magnetic substrate so as to be substantially perpendicular to the direction of the electric field.

In the method of the present invention, when no magnetic field is applied, in order to more efficiently exhibit the effect of the application of the high frequency voltage, the insulating substrate is moved in the direction of the electric field formed by the application of the high frequency voltage. Preferably placed vertically. The magnetic field strength applied to stably generate plasma is 200 to 2000 Gauss, more preferably 6 Gauss.
00 to 1000 Gauss, and it is desirable to create a magnetic field in which electron cyclotron resonance occurs in the plasma generation chamber.

0 In the present invention, when applying a magnetic field, the discharge can be stably maintained even in a high vacuum region, so the pressure in the film forming chamber in this case is preferably 1 x 10-' to 5.
X 10-3 Torr. The preferred pressure in the film forming chamber when no magnetic field is applied is 1 x 10-4 to 5 x 10
-3 Torr.

Further, the temperature of the insulating substrate during film formation is preferably 20°C.
0 to 400°C, more preferably 250 to 3
The temperature is 50°C.

According to the present invention, various polycrystalline semiconductor films can be efficiently formed at low temperatures. Examples of such polycrystalline semiconductor films include, for example, polycrystalline semiconductor films whose constituent elements are elements of group Ⅰ of the periodic table (hereinafter referred to as "group Ⅰ long crystal semiconductor films").

), a polycrystalline semiconductor film containing elements of the 1st l-Vl group (hereinafter referred to as "■■ group polycrystalline semiconductor film"), an m-th
- A polycrystalline semiconductor film whose constituent matrix is a group V element (hereinafter referred to as “
Examples include "mV group polycrystalline semiconductor film").

■As the chief crystal semiconductor film, silicon (Si), germanium (Ge), silicon germanium (SiGe)
), silicon carbide (S i C), diamond, etc.

As the n-vi group polycrystalline semiconductor film, zinc oxide (ZnO
), zinc sulfide (ZnS), zinc selenide (ZnSe),
Cadmium sulfide (CdS), cadmium selenide (Cd
Se), etc. can be formed.

■= As a group V polycrystalline semiconductor film, aluminum arsenic (
Aj! As), aluminum antimony (AnSb),
Gallium nitride (GaN), gallium phosphide (GaP)
, gallium antimony (G a S b), indium phosphide (InP), indium phosphide (InAs), indium antimony (I n S b), and the like.

The insulating substrate used to form the polycrystalline semiconductor film by the method of the present invention may be either crystalline or amorphous. Specific examples include quartz, glass, aluminum, ceramics such as boron nitride, plastics such as solid iron, and silicone resin.

1 2 As the raw material gas for forming the polycrystalline film, known gases commonly used for forming semiconductor films can be used. Raw materials that are not in a gaseous state at room temperature and pressure are used by heating and vaporizing them, or by bubbling inert gas and transporting them. For example, in the case of forming a polycrystalline silicon semiconductor, S
in.

5izH6, S iF4. S 1HFs, S 1Hz
Fz.

S 1H3F , 5i2Fh, S i C1a, S i
Examples include H2CA2°S i H8C1. Furthermore, 5iCj! Liquid materials such as No. 4 are used after being vaporized by bubbling an inert gas. In addition to the above raw material gases, Hz, Ar, He, Ne, and Kr are used to stabilize the discharge or promote the deposition reaction.

Xe, Fz, Cj! Gases such as t, HF, HCZ, etc. may be added during the deposition reaction. The additive gas can be similarly used for forming other functional thin films.

As a raw material gas for forming germanium, Ge
Ha and GeF4 are used, and CHa is used as a raw material gas for forming diamond 3.

CzHz, CzHa, CtHb, etc. are used.

As a raw material for forming silicon germanium, a mixture of silicon and a raw material gas for forming germanium is used. When forming silicon carbide, in addition to using a mixture of silicon and diamond raw material gases,
Gases such as 5i(CHs)4 can also be used.

When forming a 1l-Vl group polycrystalline semiconductor film, a compound containing a group Ⅰ element as a constituent element that is gaseous or easily gasified at room temperature and normal pressure (hereinafter referred to as a "group Ⅰ compound") is used. ) and a compound that is gaseous or easily gasified at room temperature and normal pressure (hereinafter referred to as "group II compound") containing a group III element as a constituent element is used as a raw material gas for the acid film.

A specific example of the raw material gas for the upper blood group compound is Zn(C
H8)z, Zn(C2Hs)z, Cd(C
Hs)z.

Examples include Cd(C2Hs)z.

The raw material gases for the above Group Ⅰ compounds include H, S4 S(CH3)2, S(CgHs)g, 5(
CH3) (C2H5).

Examples include Hase, 5e(CH3)z, Ox, and the like.

Similarly, when forming an m-v family long crystal semiconductor film,
A compound containing a Group element as a constituent element that is gaseous or easily gasified at room temperature and pressure (hereinafter referred to as a "Group compound"). ) and a compound (hereinafter referred to as a "V group compound") that is gaseous or easily gasified at room temperature and normal pressure and contains a group (I) element as a constituent element is used as a raw material gas for the acid film.

As a raw material for the above-mentioned group (I) compound, At+(CHs)i is used.

AIl(CgHs)a, AIl(C4H9)3.0a
(CHs)s.

Examples include Ga(CzHsh) and In(CH3)3.

Raw materials for the above Group V compounds: Toshiteha, PI(s, P(CtH)
s)s.

Examples include As H3, As(CH3)+, 5b(CH8)3, and the like.

In addition, the polycrystalline semiconductor film formed by the present invention can control the valence electrons of the polycrystalline semiconductor obtained by mixing a small amount of source gas containing other elements other than the main component elements during the formation of the deposited film. I can do it.

The apparatus for carrying out the method of forming a high-quality polycrystalline semiconductor film by the microwave plasma CVD method of the present invention described above has a film forming chamber having the configuration schematically shown in FIG. It is possible to use a plasma generation chamber having any of the configurations schematically shown in FIG. 5 (A) to FIG. 5 (G).

Typical examples of such devices are shown in Figures 7 and 8 (
Examples include those schematically shown in Figure A) and Figure 8(B). In FIG. 4, 400 is a high frequency power source for controlling ion energy, 401 is an impedance matching circuit made up of a capacitor and a coil, 402 is a conductive support,
403 is an insulating substrate, 404 is a film forming chamber, 405 is a plasma flow, 406 is an insulator, 407 is a grid electrode, 40B
409 is a plasma generation chamber, and 409 is a gas introduction pipe.

The plasma generation chamber 408 and the film formation chamber 404 are insulated by an insulator 407. The film forming chamber 404 is provided with a conductive support base 402 to which a high frequency power source 400 is connected via an impedance matching circuit 401, and a high frequency voltage is applied between the green electrode 407 and the conductive support base 402. By this, the plasma is generated in the plasma generation chamber 408,
The energy of ions in the plasma flow 405 flowing into the film forming chamber 404 is controlled and guided to the surface of the insulating substrate 403 to form a polycrystalline semiconductor film.

5(A) to 5(G) each show a typical configuration example of the plasma generation chamber. Fifth (A)
In Figures to Figures 5(G), 500 is a microwave;
01 is a microwave waveguide, 502 is a plasma generation chamber, 5
03 is a microwave introduction window, 504 is a magnetic field generator, 50
5 is a ground electrode, 506 is a rigitano coil, 507 is a helical antenna, 508 is a coaxial mouth/throat antenna, 5
09 is a leaky wave antenna, 5 0 is a variable axis length plunger of a cavity resonator, and 511 is a gas introduction pipe. Fifth (A)
The figure shows an example of a method in which microwaves are directly introduced into a plasma generation chamber 502 having a cavity resonator structure through a window made of ceramics such as quartz, alumina, magnetic screws, zirconia, silicon nitride, boron nitride, etc., for discharge. 5
(B) shows an example of a non-polar discharge type ECR in which the plasma chamber 502 has a cavity resonator structure, and FIG. 5 (C) shows impedance matching by changing the axial length of the cavity resonator 502 with a plunger 510. Fig. 5(D) shows an example of ECR plasma generation using a girder coil 506, and Fig. 5(E) shows a helical antenna 5.
Figure 5 (F) shows an example of ECR plasma generation in which microwaves are introduced by coaxial rod 508.
) The figure shows an example of a method for introducing microwaves and discharging them using a leaky wave antenna 509. The method of generating plasma by microwave discharge is shown in Figures 5(A) to 5(G).
It is not particularly limited to the figure. The main configuration of the plasma generation chamber shown in FIGS. 5(A) to 5(G) consists of a microwave introducing means and a raw material gas introducing means.

Plasma generation methods can be broadly divided into eight types: non-polar discharge method and antenna method. Figure 5 (A), Figure 5
The plasma generation section shown in Figures (B) and 5 (C) is of a non-polar discharge type, and since no impurities are mixed in during discharge, it is suitable for decomposing a large amount of gas by inputting high-power microwaves. ing. Further, other antenna systems are not suitable for high-power microwave input, but have the advantage that discharge can easily occur stably. The plasma generating section shown in FIGS. 5(A) to 5(G) is appropriately selected depending on the deposition application.Furthermore,
A magnetic field may be applied to the plasma generation chamber in order to stabilize the discharge and efficiently generate high-density plasma.

The area where discharge can occur can be expanded by applying a magnetic field. Figure 5(B), Figure 5(D), Figure 5(E), Figure 5(
F) The figure shows the magnetic field application method. The preferred magnetic field strength of the magnetic field applied for plasma generation is 200 to 2,000 Gauss, more preferably 600 to 1,000 Gauss, and creating a magnetic field strength range in which electron cyclotron resonance occurs within the plasma generation chamber is a method for using microwave energy. Desirable for effective use.

The method of the present invention can be carried out using any suitable apparatus configured to carry out the method of the present invention. A preferable example of such an apparatus is an apparatus having the configuration shown in FIG. 4 for the film forming chamber and any of the configurations shown in FIGS. 5(A) to 5(G) for the plasma generation chamber. I can give an example.

Specific examples of such devices include devices having the configurations shown in FIGS. 7, 8(A), and 8(B). The apparatus shown in FIG. 7 is a combination of a film forming chamber configured as shown in FIG. 4 and a plasma generation chamber configured as shown in FIG. 5(B). The apparatus shown in FIG. 7 was used in experiments 5 to 8 described above.
Since the device has already been explained, the explanation thereof will be omitted here.

The apparatus shown in FIG. 8(A) is a combination of a film forming chamber configured as shown in FIG. 4 and a plasma generation chamber configured as shown in FIG. 5(C). The device shown in FIG. 8(B) is similar to the device shown in FIG. 0 This device has the same configuration as the device shown in FIG. 8 (A).

In FIG. 8, 800 is a high frequency power source for applying an ion control electric field, 801 is an impedance matching circuit, 802 is a conductive support, 803 is an insulating substrate, 804 is a film forming chamber, 80
5 is a plasma flow, 8 (16 is a recorder, 807 is a green electrode (ground electrode), 808 is a plasma generation chamber, 809 is a microwave, 810 is a microwave waveguide, 811 is a quartz Pelger (microwave introduction window) ), 812 is a plunger for varying the axial length of the cavity resonator, and 813 and 814 are gas introduction pipes.

The difference between the apparatus shown in FIG. 7 and the apparatus shown in FIG. 8 is the plasma generation chamber. In the apparatus shown in FIG. 8, the plasma generation chamber has a structure in which a quartz Pelger is provided in a cavity resonator, and a microwave waveguide 81 is connected to the side of the cavity resonator.
Microwaves are introduced from 0, and the length of the cavity resonator is adjusted with a plunger 812 so that discharge occurs stably, and plasma is generated within the quartz Pel jar 811. The method of operation is the same as the apparatus of FIG. 8, except that no magnetic field is applied.

When forming a functional thin film using the microwave plasma deposition method of the present invention, there are two methods: [b ) There are two ways to form a deposited film by introducing raw material gas for plasma generation into the plasma generation chamber and introducing raw material gas for deposition into the deposition chamber (81 and Mt.). Which method is used to form the deposited film is appropriately selected depending on the desired deposited film or the raw material gas used.

In the above gas introduction method, when introducing a gas that is not easy to decompose into the raw material gas, it is better to adopt the method (al). When using a gas that is easy to decompose as the raw material gas, it is better to use the method (bl). May be adopted.

In the formation of a polycrystalline semiconductor film using the microwave plasma CVD method of the present invention, in order to further promote the reaction,
It is also possible to apply thermal energy or light energy to the surface of the sample substrate.

〔Example〕

2 Hereinafter, the present invention will be specifically explained based on Examples,
The present invention is not limited only by these examples.

As an example using the present invention, a polycrystalline silicon film was deposited using the microwave plasma deposition apparatus configured as shown in FIG. 7, which was used in Experiment 5, according to the following procedure.

First, a cleaned #7059 glass substrate 713 manufactured by Corning Corporation is placed on the conductive support 708 in the film forming chamber 702, and then a temperature controller (not shown) is used to maintain the surface temperature of the glass substrate at 300°C. control, 2x
The plasma generation chamber 701 is evacuated to a pressure of 10-'Torr, and H250sccm and S
i Ha 5 sccm was introduced, and the pressure inside the film forming chamber 702 was controlled to 2 x 10-' Torr. Immediately, a magnetic field generator 709 is used to generate 8
A magnetic field of 75 Gauss is generated and 300 W of microwave power is inputted through the quartz microwave introducing window 703. At the same time, a high frequency voltage for ion control is applied from the high frequency power supply 700 via the matching circuit 714 at a frequency of 100 MHz and a voltage of 30 W.
A film was formed by applying a voltage of 0 V to the support table 708 to form a deposited film with a thickness of 2.1 microns.

The deposition rate was 15 A/sec. As a characteristic evaluation of the formed silicon film, crystallinity was evaluated by RHEED (reflection high energy electron diffraction). Next, an electrode was formed by vapor deposition on the obtained deposited film, and the Hall effect was measured using the van der Parra method. The diffraction results by RHEED confirmed the Sposoto pattern, indicating that it was a polycrystalline silicon film with good crystallinity. The Hall mobility determined from Hall effect measurement is 64 cd/V-sec.
There was a time.

Using the deposition apparatus shown in Fig. 6 above, apply a DC voltage of -4 to the sample stage 60B.
A silicon deposited film having a thickness of 1.8 microns was formed in the same manner as in Deposited Film Formation Example 1, except that 00V was applied.

The deposition rate was 13 persons/see.

5'(4) The RHEED diffraction pattern of the resulting deposited film was ring-shaped, indicating that it was a silicon polycrystalline film with poor crystallinity.Hole mobility was 4cl'II/V-3ec.

Example 2 In Example (■), only the internal pressure was set to 2X 10-3 Torr.
A silicon deposited film with a thickness of 2.5 micrometers was formed in the same manner except that . The deposition rate was 7 persons/sec. The evaluation method was also the same as in Example 1.

The RHEED diffraction pattern was a sposoto pattern, indicating polycrystalline silicon with good crystallinity. Hall mobility is 56c
ffl/V-sec.

Example 3 In order to examine the effect of applying a magnetic field, a silicon deposited film having a thickness of 2.0 microns was formed in the same manner as in Example except that no magnetic field was applied. Deposition rate is 11 people/sec
Met. The evaluation method was the same as in Example 1.

The RHEED diffraction pattern was a polycrystalline pattern with good crystallinity. The Hall mobility was 543 cJ/V-sec.

Comparative Example 2 Using the same method as in Deposited Film Formation Example 1, using the apparatus shown in FIG.
Frequency 13.56MHz, voltage 400v on sample stage 708
A high frequency voltage of 1.6 μm was applied to form a silicon deposited film with a thickness of 1.6 μm on a #7059 glass substrate manufactured by Corning. The deposition rate was 11 persons/see. Although the RHEED diffraction pattern of the obtained deposited film was ring-shaped and polycrystalline silicon with poor crystallinity, the hole mobility was 1 cIIl/V-sec.

Example 4 A polycrystalline silicon deposited film was formed using the microwave plasma CVD apparatus shown in FIG. 8(B).

First, a cleaned #7059 glass substrate manufactured by Corning Corporation as a deposition substrate 803 is mounted on a sample stage 802 for voltage application, and after the pressure inside the film forming chamber 804 is evacuated to a pressure of 1 x 10-6 Torr, the glass substrate Keep the surface temperature of 803 at 300℃, and inject H210scc from gas introduction pipe 813.
Introduce m and A r 5 sccm, and S i Ha 10 sccm from the gas introduction pipe 814.
m was introduced to control the pressure inside the film forming chamber 804 to 5 mTorr. Immediately apply 300W of microwave power to the waveguide 8.
10 into the plasma generation chamber 808 to start discharge, and at the same time, the high frequency power source 800 generates a frequency of 50M.
A high frequency wave of Hz and voltage of 100 V is applied to the support base 802,
Film thickness 1.5. A silicon deposited film of chlorine was formed. The deposition rate was 17 persons/sec. As a result of RHEED measurement of the obtained silicon deposited film, the diffraction pattern was found to be spot-shaped and polycrystalline.

Further, an electrode was formed on the obtained deposited film by mounting, and the Hall mobility was determined to be 20 cJ/V-sec by measuring the Hall effect using the Van der Barra method.

In addition, when an amorphous silicon film was deposited using the same method as described above using the apparatus shown in FIG. 8 (A) in which the deposition substrate was installed perpendicular to the plasma flow, and its properties were measured, the hole mobility was 20 cnl. /V-see.

In the microwave plasma deposition apparatus shown in FIG. 8 (B),
Except that a high frequency electric field was not applied to the support base 802 and it was grounded.
A silicon deposited film having a thickness of 2 cm was formed in the same manner as in Deposited Film Formation Example 4.

The deposition rate was 16 persons/sec. The obtained deposited film was evaluated in the same manner as in Deposited Film Formation Example 4.

A halo was observed in the RHEED measurement, indicating that the material was amorphous silicon. In addition, the Hall mobility is 0.7 cffl/
It was V-sec.

Using the apparatus shown in Fig. 7, film formation was carried out in almost the same manner as in Example 1, and polycrystalline zinc selenide (ZnS) was formed.
e) was formed.

First, a cleaned #7059 glass substrate manufactured by Corning Corp. was mounted on a conductive support 708 as an insulating substrate 713 for deposition, and after evacuating the inside of the film forming chamber 702 until the pressure became 8×10 Torr or less, the The surface temperature of the glass substrate 713 was controlled at 350°C, and H28
sccm and 5e(CHs)z7 8 3sccffl were introduced, and Zn(
CHs) at 21 sccm was introduced to control the pressure in the film forming chamber 702 to 2X 10-' Torr. Immediately, a magnetic field of 1000 Gauss is generated in the plasma generation chamber 701 by the magnetic field generator 709, and 200 W of microwave power is inputted through the quartz microwave introduction window 703, and at the same time, the high frequency power source 700 generates a 1000 Gauss magnetic field through the matching circuit 713. Film formation was performed while applying a high frequency voltage for ion control at a frequency of 50 MHz and a voltage of 200 V to the conductive support base 708, thereby forming a deposited film with a thickness of 2.6 microns. When the deposited film of zinc selenide obtained was observed by RHEED, a spot pattern was obtained, and it was confirmed that the film had good crystallinity. Also,
When measuring the Hall effect, the Hall mobility was 45cJ/■・s
The film was formed under the conditions for forming the polycrystalline silicon thin film of Example 1, and an attempt was made to fabricate a thin film transistor having the structure shown in FIG. In FIG. 9, 900 is a transparent insulating substrate, 901 is a polycrystalline semiconductor layer, 902 is an impurity doped layer 1, 903 and 904 are a source electrode and a drain electrode, respectively, 905 is a gate insulating film, and 906 is a gate electrode. be.

The outline of the manufacturing procedure of the thin film transistor shown in FIG. 9 is as follows. First, a polycrystalline silicon film with a thickness of 3000 nm was formed as a polycrystalline semiconductor layer 901 using the same method as in Example 1 on a cleaned #7059 glass substrate made by Corning Inc. as a transparent insulating substrate 900, and using PH3 gas. After forming an impurity doped layer of n''' layers by plasma doping, and depositing Al to a thickness of 1,000 layers by electron beam evaporation, photolithography was used to form an A12 layer and an n''' layer.
The layer is patterned to form source and drain electrodes 903 and 904. Next, a silicon nitride film with a thickness of 2,500 wafers was formed using a plasma CVD method using SiH4 gas and NH3 gas to serve as a gate insulating film. Next, after 5000 AA was deposited by electron beam evaporation, it was patterned by photolithography to form the gate electrode 905.
A polycrystalline thin film transistor was fabricated. When I checked the function of the transistor 0 transistor, I found that the current ratio of 0N10FF is axto', and the carrier mobility is 52alt/V"S
In place of the Corning #7059 glass substrate used in Example 6, we used a substrate made by coating soda lime glass with silicon oxide and then coating it with a silicon nitride film using the plasma CVD method. A polycrystalline thin film transistor was manufactured using the same method as in Example 6.

When we checked the function of the fabricated transistor, it was found to be 0N1.
Current ratio at 0FF is 4X10' and carrier mobility is 31
It was cJ/V・s6c.

From the comparison between Example 1 and Comparative Example 1.2 and the comparison between Example 4 and Comparative Example 3, it is clear that the high-quality polycrystalline silicon thin film is heated to low temperature by applying the high-frequency electric field according to the present invention. It can be seen that it is formed by A comparison between Example 2 and Example 3 shows that by applying a magnetic field in the present invention, the quality of the polycrystalline silicon thin film is improved and the deposition rate is also increased.

In Example 5, it can be seen that the compound semiconductor can be easily deposited on an insulating substrate using the present invention, and the obtained film quality is also good. In Examples 6 and 7, thin film transistors were manufactured using polycrystalline silicon as a semiconductor layer using the method of the present invention, and it was confirmed that the transistors exhibited good transistor characteristics even though polycrystalline silicon was formed at a low temperature of 400° C. or lower. can.

(The following is a blank space) 2 [Summary of the effects of the invention] As described above, according to the present invention, microwave plasma C
We have solved the problems with the conventional method of forming polycrystalline semiconductor films using the VD method or ECR microwave plasma CVD method, and can efficiently form high-quality polycrystalline semiconductor films at low temperatures on large-area insulating substrates that can be easily handled manually. It can be formed as follows. According to the present invention, the semiconductor layer of a TPT for an active matrix liquid crystal display can be made of polycrystals by low-temperature film formation, making the TPT high-performance and low-cost. can do.

[Brief explanation of drawings]

FIG. 1(A) and FIG. 1(B) are schematic configuration diagrams of an ion energy measuring device used to explain the present invention in detail. Figure 2(A), Figure 2(B), Figure 2(C), Figure 2(D)
) Figures are the ion energy profiles obtained in experiment 1, respectively. Figures 2(E) and 2(F) are
These are the ion energy profiles obtained in Experiment 2. FIG. 2(G) is a diagram showing the frequency of the applied high-frequency voltage and the ratio of the half-width to the peak energy of ions, obtained in Experiment 3. FIG. 3 (A) is a diagram showing the relationship between the applied high frequency voltage value and the crystallinity obtained from Experiment 5. FIG. 3(B) is a diagram showing the relationship between the pressure in the film forming chamber and the crystallinity obtained from Experiment 6. Figure 3 (C) is a diagram showing the relationship between substrate temperature and crystal obtained from Experiment 7. Figure 3 (D) is a diagram showing the relationship between substrate temperature and crystal obtained from Experiment 7.
FIG. 3 is a diagram showing the relationship between substrate temperature and crystal grain size obtained from FIG. FIG. 4 is a schematic diagram of a film forming chamber used to carry out the present invention. 5(A) to 5(G) are schematic diagrams of a plasma generation chamber used to carry out the present invention. Figure 6 shows an RT using a conventional ECR plasma device.
B D (Reactive I on Beam
1 is a schematic configuration diagram of a film forming apparatus using a deposition method. FIG. 7 shows a film forming apparatus suitable for carrying out the method of the present invention, which combines the film forming chamber shown in FIG. 4 and the plasma bottom chamber shown in FIG. 5(B). 8(A) and 8(B) show the film forming chamber in FIG.
(C) This is a film forming apparatus suitable for carrying out the method of the present invention, which is combined with the plasma generation chamber shown in the figure. FIG. 9 is a schematic cross-sectional view of a thin film transistor obtained by forming a semiconductor layer made of a polycrystalline silicon thin film by the method of the present invention. In Figures 1.4, 5, 6.7 and 8, 100.40
0,700,800...High frequency power supply, 101...Capacitor, 102.106,600...DC power supply, 103,. 4
02,608,708,802... Conductive support stand, 104... Ion reflecting grid, 105... Ion collection electrode, 107... Insulating substrate, 108... Micro current meter, 109. 406,642,712,806... Insulator, 110.407,505,706,807... Ground electrode, 111, 408. 592. 601,701
,808...Plasma generation chamber, 112.504,709...Magnetic field generator, 113
507...Helical antenna, 114.501,60
4,810...Microwave waveguide, 500.809.
...Microwave, 115...Vacuum container, 118,119...Tuner 120...Vacuum glass, 116.409,605,606,705,70681
3.814... Gas introduction pipe, 117.405, 607, 707, 805... Plasma flow, 503.603, 703.811... Microwave introduction window, 506... Risitano coil, 508. ...Coaxial mouth-nod antenna, 509...Leaky wave antenna, 403.613,713,803...Substrate for deposition, 4
01.713,801... Impedance matching circuit,
510.812...Cavity resonator axial length variable plunge F
i 7 Ya 611,7], 1,807... Green electrode for applying electric field, 404, 502, 602, 702, 804... Film forming chamber. In FIG. 9, 900...transparent insulating substrate (glass substrate), 901...
Polycrystalline semiconductor layer, 902... Impurity doped layer, 903... Source electrode, 904... Train electrode, 905... Gate insulating film, 906... Gate electrode. 8 Fig. 2 (A) f = 40.7 MHz Ion energy (eV) Fig. 2 (B) f = 13.56 M port 2 Ion energy (eV) Fig. 2 (C) Ion energy (eV) Fig. 2 (E ) figure f=40.780Z Ion energy (eV) Ion energy (eV) Second (') figure f=40.7MHz Ion energy (eV)

Claims (8)

[Claims] (1) Using a film forming apparatus by microwave plasma CVD method having a plasma generation chamber and a film formation chamber equipped with a microwave introduction means, a raw material gas is introduced into the plasma generation chamber, and the microwave is introduced at the same time. Microwave energy is injected into the plasma generation chamber through a means to cause discharge to decompose the source gas and generate plasma, and A method for forming a deposited film on the surface of an insulating substrate placed on a conductive support set in the film forming chamber by causing the plasma to flow into the film forming chamber through a perforated grid electrode, the method comprising: A method for forming a polycrystalline semiconductor film, characterized in that the deposited film is formed while applying a high frequency voltage of 20 to 500 MHz between the grid electrode and the conductive support. (2) Claim (1) wherein the deposited film formed by controlling the high frequency voltage in the range of 100 to 500 V is a polycrystalline film.
) The method for forming a polycrystalline semiconductor film described in . (3) Increase the pressure inside the film forming chamber to 1×10^-^6 to 5×
Claim (2) in which the film is formed while maintaining the pressure at 10^-^3 Torr.
) The method for forming a polycrystalline semiconductor film described in . (4) The method for forming a polycrystalline semiconductor film according to (2), wherein the film is formed while maintaining the insulating substrate at a temperature in the range of 200 to 400°C. (5) Microwave plasma C having a plasma generation chamber and a film forming chamber equipped with microwave introduction means and magnetic field generation means
Using a film forming apparatus based on the VD method, a magnetic field is applied to the plasma generation chamber by the magnetic field generation means, raw material gas is introduced, and at the same time microwave energy is applied to the plasma generation chamber via the microwave introduction means. The raw material gas is decomposed to generate plasma by generating a discharge, and the plasma is introduced into the film forming chamber through a multi-perforated grid electrode provided between the plasma generating chamber and the film forming chamber. A method for forming a deposited film on the surface of an insulating substrate placed on a conductive support set in the film forming chamber, the method comprising: 1. A method for forming a polycrystalline semiconductor film, which is carried out while applying a high frequency voltage of 20 to 500 MHz between the polycrystalline semiconductor film and the support. (6) The deposited film formed by controlling the high frequency voltage in the range of 100 to 500 V is a polycrystalline film.
) The method for forming a polycrystalline semiconductor film described in . (7) Increase the pressure inside the film forming chamber to 1×10^-^6 to 5×
Claim (6) in which the film is formed while maintaining the pressure at 10^-^3 Torr.
) The method for forming a polycrystalline semiconductor film described in . (8) The method for forming a polycrystalline semiconductor film according to (6), wherein the film is formed while maintaining the insulating substrate at a temperature in the range of 200 to 400°C.