JPH0635663B2 - Surface treatment method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention creates predetermined radiant light and reactive species by plasma and uses them to produce sensors, optical parts, acoustic products, semiconductor devices, etc. Surface treatment method and apparatus for performing surface treatment such as film formation such as insulator film, protective film, semiconductor film, metal film, etching, surface cleaning, surface modification, etc., and surface hardening treatment for blades, cutting tools, etc. Regarding

(Prior art and its problems) A method of activating a gas by a photochemical reaction or a reaction using an active species, depositing a target substance on the surface of a substrate to form a thin film, or performing a treatment such as etching or surface modification is In recent years, rapid progress has been made due to the fact that the treatment can be carried out at a low temperature and the photochemical selectivity or the selectivity by the active species enables the treatment which has not been hitherto available.

Here, the active species refers to free species (radicals), excited species, electrons, ions, plasma, or a mixture thereof.

The conventional photochemical surface treatment methods are roughly classified into two. One is to use a discharge lamp as the light source,
The other is a method using a laser as a light source.

However, the method using a discharge lamp generally has a low brightness of radiated light, and the method using a laser requires an expensive laser body.

Further, in the usual case, in those processing apparatuses, the light source and the processing chamber are separated by a window, and especially in the case of photo CVD or the like, foreign matter is deposited on this window and the emitted light is attenuated. The problem arises.

As inventions for improving this, there are inventions disclosed in JP-A-59-16966 and JP-A-60-24373.

In the former invention, the light source unit and the processing unit are installed in the same container, and as the light source, so that it can be estimated from the specification,
Glow discharge light from hot cathode discharge, AC discharge or DC discharge is used to supply a protective gas around the discharge electrode to protect the electrode, thereby stabilizing the discharge or stabilizing the light source. ing. However, this configuration complicates the structure of the apparatus and introduces a gas that is not directly related to the surface treatment into the treatment system, which limits the properties of the surface treatment or adversely affects the treatment. Is born.

The latter invention utilizes the discharge light of the hollow cathode discharge as a light source, and is an application of the applicant of the present application. As described in the specification, it produces a very good quality amorphous silicon hydride film, and so forth. Although effective, on the other hand,
Subsequent experiments have revealed that the processing speed such as the film forming speed is extremely slow and cannot be put to practical use.

In general, active species can be created by irradiating a substance with light, electrons, etc., but the active state created by light is an active state in which optical transition is not prohibited, or an active state in which the light transition is not prohibited. While the active state is generated only by the crossing or relaxation, the active state generated by the collision of particles in the plasma or electron beam is not limited to the above, and the active state in which optical transition is prohibited can be easily generated. The transition expands, which creates a variety of active species containing harmful impurities, unlike the case of light. Since most of the conventional techniques for forming a film by plasma directly contact the plasma with the substrate, these harmful impurities and charged particles in the plasma impact the substrate to cause damage, and the impurity is added to the substrate. Then, for example, there is a defect that the electrical characteristics of the semiconductor device formed on this substrate are deteriorated. Such deterioration may be caused by, for example, a change in Vth in a MOS semiconductor device or h in a bipolar semiconductor device.
It strongly appears in the fluctuation of fe. When the degree of integration of semiconductor devices becomes extremely large as in recent years, the impact of minute charged particles may cause a significant deterioration in electrical characteristics. The development of damage-free processes, such as the use of light without light, has become particularly desirable.

On the other hand, in the surface treatment for the purpose of hardening blades, cutting tools, etc., it is necessary to form the diamond-like film and the BN film at high speed. Therefore, free species, excited species,
It has been desired to develop an apparatus for performing a high-speed surface treatment by placing a substrate on a place where the concentration of active species such as ions and plasma is increased.

The invention that realizes such a damage-free process and a high-speed surface treatment process is disclosed in JP-A-61-2222534 and Japanese Patent Application No.
There is an invention of 0696646.

Both of the inventions are filed by the applicant of the present application, and as described in the specification thereof, it is possible to perform extremely high quality surface treatment.

Also, the device of the invention of JP-A-61-2222534 is J. Vac Sc
It is important as a thin film forming apparatus for semiconductor devices as described in P.475 to P.479 of i.Technol.A4 (3) (1986).

However, both of these inventions require a high-power alternating power source and a power supply system, and thus have the disadvantages that the device becomes large, the cost is high, the power consumption during operation is large, and the cost of the surface treatment is high. . In addition, there is a drawback that a large power transmission loss and a large amount of power consumption parts are consumed, and that maintenance takes time.

(Object of the Invention) The present invention is useful for surface treatment and has a strong synchrotron radiation and / or
Alternatively, a surface treatment method and apparatus capable of stably producing active species and performing high-quality and effective surface treatment,
The objective is to achieve low power consumption, downsizing, cost reduction, and low maintenance.

(Structure of the Invention) In the first invention of the present application, LTE discharge is generated by introducing a predetermined gas into a space to which alternating electric power is applied,
In a surface treatment method, in which at least one of radiant light and active species generated by the plasma of the LTE discharge is guided to the surface of the substrate placed in or near the LTE discharge to perform a predetermined treatment on the surface of the substrate. The above object is achieved by a method of creating or maintaining the LTE discharge in a magnetic field.

In addition, a second invention of the present application is to realize an industrially usable device with the following configuration by using the first invention. That is, it is a reaction chamber containing the gas to be treated, an alternating power source, a discharge chamber having a discharge space to which the alternating power is applied by inductive coupling, capacitive coupling or cavity resonance, and a predetermined discharge space. Means for introducing the gas and an irradiation means for guiding at least one of the radiant light generated in the discharge plasma of the discharge space and the active species to the surface of the substrate to be treated in the reaction chamber, thereby performing the LTE discharge. The method is instrumented in a configuration such that it has an alternating power and magnetic field of sufficient strength to create or maintain.

A third invention of the present application uses the method of the first invention,
The industrially usable device is realized by the following configuration different from the second invention. That is, it is an alternating power source, a discharge treatment chamber having a discharge space to which the alternating power is applied by inductive coupling, capacitive coupling or cavity resonance, a means for introducing a predetermined gas into the discharge space, and A means for accommodating a substrate to be treated in the discharge plasma of the discharge space, a means for treating the surface of the substrate, and an alternating electric power and a magnetic field having a strength capable of creating or maintaining an LTE discharge in the discharge space are provided. The above method is implemented by a device having such a configuration.

(Operation) By creating a magnetic field in the discharge space in which the LTE discharge is created and maintained, the output of the alternating-current power supply can be reduced and the size can be reduced.

As a result, low power consumption, low component consumption, and low cost surface treatment are possible. Also, maintenance time is short.

(Embodiment) FIG. 1 shows a surface treatment apparatus of an embodiment of the apparatus of the second invention for realizing the method of the first invention of the present invention. Reference numeral 10 is a discharge chamber, and 20 is a reaction chamber. The discharge chamber 10 is composed of a high frequency (several kHz to several hundred MHz) power source 1, a switch 2, a coil 3, a discharge tube 11 and a magnet 4 as a magnetic field generating mechanism, and a high frequency voltage of the power source 1 is applied to the coil 3. Then, a discharge is generated in the discharge space 15 that is inductively coupled to the high frequency inside the discharge tube 11. One end of the coil 3 can be selected and grounded by the switch 2. A magnetic field having a predetermined strength can be created in the direction B in the discharge space 15 by the magnet 4.

.. Note that instead of the coils, a pair of plate electrodes sandwiching the discharge tube 11 may be provided, and electric power may be applied to the plate electrodes to form the capacitively coupled discharge space 15.

When using high-frequency power in the microwave region (GHz order), a microwave cavity is installed so as to surround the discharge tube 11 instead of the coil. At this time, the cavity resonance discharge space 15 is used.

Further, the direction of the magnetic field may be perpendicular to the arrow in the figure, and the magnetic field may not be a static magnetic field, for example,
A dynamic magnetic field such as an alternating magnetic field or a rotating magnetic field (one whose magnetic field strength and direction change with time) may be used. ... Then, the discharge gas is introduced from the direction of the flow 13 through the valve 12 into the discharge tube 11 in which the discharge has occurred as described above.

The discharge tube 11 is usually made of an insulating material, and its material is preferably quartz glass, sapphire, ceramics, or the like. When quartz glass is used, the quartz glass may melt due to the high temperature of the discharge plasma. Therefore, the discharge tube 11 may be a double tube of quartz glass, and cooling water may flow between the inner and outer tubes. Even if other materials are used, air cooling or water cooling may be performed for the same reason.

A feature of the present invention is to provide a magnetic field of a predetermined strength in the discharge space 15 to facilitate the creation or maintenance of LTE plasma.

Before describing the effect of magnetic field, LTE without magnetic field
First, the conditions for creating and maintaining plasma will be described.

In the apparatus of FIG. 1 showing this case, the high frequency glow discharge is first generated as the applied high frequency power is increased, but when the higher power is applied, the light emission from the plasma dramatically increases and the LTE ( Local Termal Equ
ilibrium local thermal equilibrium) (strictly speaking, "quasi-thermal equilibrium state", but there is no appropriate scientific term) Plasma 5 is observed to occur. The generation of LTE plasma is often hysteretic (described later in detail). The plasma 5 is very bright and often exhibits a spectral pattern different from the normal DC glow discharge. For example, assuming that the introduced gas is hydrogen, in the case of hydrogen, in the case of normal DC glow discharge or high frequency glow discharge, first, there is a continuous spectrum from the visible region to the ultraviolet region due to hydrogen molecules. In addition to this, it is possible to observe the Balmer series and Lyman series luminescence due to the hydrogen atom. However, the emission of these series at this time is relatively weak, and therefore the color of the emitted light is white purple.

However, when the LTE plasma 5 is generated, the color of the radiated light is red, which has a very high brightness by visual observation, and it is known that this is because the brightness of the Balmer system of the emission of hydrogen atoms is very high. . At the same time, it is not visible in the visible part because it is not in the visible part, but it can be confirmed by measurement that the brightness of the Lyman system is also very high. The manner in which the brightness is increased is shown in FIG. (The wavelength of the light emission when the LTE discharge is generated is determined by the type of gas used for plasma generation. This light emission is one of the great features of the LTE discharge.) Here, A in FIG. Discharge created power, B LTE
Discharge sustaining power.

Lyman α light has a wavelength of 121.6 nm, and as is well known, when this wavelength is used, silane and disilane can be directly decomposed. Moreover, in the case of this light, Mg
There is also an advantage that an optically transparent material such as F ₂ or LiF and an Al reflector having a MgF ₂ coating can be used, and it is extremely useful because an optical system is extremely easy to assemble.
So far, this wavelength light has not been used so much because there is no good light source that can take out the high brightness of the Lyman α light. The high frequency LTE plasma light described above is valuable as a light source in this sense.

In addition to hydrogen, any gas such as nitrogen, argon, helium, mercury, and the like, or a mixed gas thereof is also useful as the above-mentioned introduced gas, and produces an LTE discharge plasma that emits useful light of high brightness.

Continuing further, if the above introduced gas is hydrogen, LTE
It can be confirmed by emission spectroscopic analysis that an extremely large amount of excited states of hydrogen atoms and hydrogen molecules and active species such as hydrogen radicals and ions are present in the plasma, as compared with normal high frequency glow discharge. The production of a large amount of active species in the LTE discharge plasma is the same in the case of other gases such as nitrogen, and FIGS. 3 and 4 show the results of vacuum ultraviolet emission spectroscopy analysis of nitrogen. . FIG. 3 is an emission analysis of LTE plasma, and FIG. 4 is an emission analysis of high frequency glow plasma. Both plasmas use the same device
It was obtained under the conditions of 3.56 MHz, 3.2 kw, pressure of 70 mTorr, and N ₂ flow rate of 30 sccm. Under the conditions for making this device, since the two states of LTE and high frequency glow shift to each other in a hysteresis manner, it is possible to create and compare two states of LTE and high frequency glow under the same conditions. This is similar to hydrogen, see FIG. The vertical axis indicating the emission intensity is
3 and 4 are arbitrary units, but LTE 3rd
The scale on the vertical axis of the graph in the figure is reduced to 100 times the intensity of the scale on the vertical axis of the graph in FIG. 4 for glow discharge. When comparing with the light intensity of 120 nm, the LTE Has an emission intensity 120 times that of a high frequency glow. And in the case of nitrogen as well as in the case of hydrogen described above, the LTE plasma has a strong brightness of short wavelength light,
Since the spectrum belongs to light emission from nitrogen atoms, it is clear that the LTE plasma contains a large amount of active species, particularly nitrogen radicals. (Reference: J. Vac.
Sci.Technol.A4 (3) (1986) 475-479) Similar results are obtained not only for hydrogen and nitrogen but also for oxygen and other gases. Comparing the high frequency glow discharge and the high frequency LTE plasma discharge, there are the following differences a, b, c, d between them.
Even if conditions 1 and 2 of c and d are omitted, the two can be clearly distinguished from the rest.

(A) The high frequency glow discharge tends to spread the light emitting part,
On the contrary, in the high frequency LTE plasma discharge, the light emitting portions tend to be locally concentrated.

(B) The emission patterns of both LTE plasma discharge and high-frequency glow discharge have different spectral patterns. It is clear that the electronic states also differ due to the difference in the spectra. When the gas is a polyatomic molecule, in the high frequency LTE plasma discharge, vibrational and rotational mode excitations that are not seen in the high frequency glow discharge are often observed.

(C) As described above, the high-frequency glow discharge state and the high-frequency LTE plasma discharge state often transit to each other by drawing a hysteresis loop with the discharge power, the discharge pressure, etc. as parameters, and the discharge impedance between the two discharges. to differ greatly. This transition is most dependent on the intensity of the discharge power supplied from the power supply to the discharge chamber. This will be described further below.

(D) The high frequency LTE plasma discharge has much higher brightness than the high frequency glow discharge plasma. The difference is remarkable.

For example, in the case of a gas such as helium, the discharge impedance does not change in a hysteresis manner, so it is difficult to determine the transition between the high frequency glow discharge and the high frequency LTE plasma from the impedance alone, but it becomes high when the high frequency LTE plasma discharge state is reached. It was observed that a bright plasma was localized and both discharges could be visually discerned.

In addition, the hysteresis may disappear depending on the size of the discharge chamber 10. This phenomenon varies depending on the pressure region even when the same nitrogen discharge is used, but the hysteresis characteristic disappears when the inner diameter of the discharge chamber is about 8 cm or more. In this way, even when the hysteresis disappears due to helium, nitrogen, etc., the high frequency glow discharge state and the LTE discharge state can be easily distinguished.

337. due to the C ³ IIu-B ³ IIg transition of the nitrogen molecule.
The change in the emission intensity of 1 nm light with power is shown in FIG. Here, A and B are defined as the same as those in FIG. Although there is no clear hysteresis in FIG. 5 as compared with FIG. 2, the emission intensity increases due to the formation of LTE plasma, and the distinction between the two states is clear. (Reference: Proceedings of the 26th Joint Lecture Meeting on Vacuum P74-P75).

By the way, the curve of the emission intensity of the nitrogen molecule shows an upward convex change as shown in FIG. 5, but the emission of the nitrogen atom shows a downward convex change.

Next, the magnetic field effect, which is the greatest feature of the present invention, will be described.

The first point of the effect is that the positions of the LTE discharge creation power A and the LTE discharge sustaining power B shown in FIG. 2 are changed by creating a magnetic field of a predetermined strength in the discharge space 15.

Normally, when the magnetic field becomes strong, the LTE discharge creation powers A and L
The TE discharge maintaining power B shifts to the low power side, and the LTE plasma 5 can be created and maintained without applying large power.

As described above, the LTE plasma 5 often has a lower impedance than that in the high frequency glow discharge state. For this reason, a power source capable of passing a large current, a cable (waveguide), an impedance matching circuit, etc. are required.
The power supply and the impedance matching circuit occupy a large volume in space and are expensive in price. This problem,
Under the same pressure, as described above, a magnetic field is created in the discharge space 15 to substantially eliminate the magnetic field.

The second effect is that the discharge pressure can be lowered. That is, the maximum dischargeable pressure when the magnetic field does not exist in the discharge space 15 is 10 ⁻³ Torr. However, if a magnetic field of about 500 Gauss or more is created in the discharge space 15,
Discharge is possible even under a low pressure of ^-5 Torr, and the discharge can be maintained.

Being able to create and maintain a discharge under low pressure has the following advantages.

(A) Since the mean free path is long, the life of the active species is long,
Easy to use active species.

(B) When the pressure is reduced, it becomes possible to generate the LTE plasma with low power.

(However, academically perfect thermal equilibrium state ... LTE state ...
Is easier to obtain when the pressure is high. However, as described above, in the present invention, since there is no appropriate scientific term to be expressed, including quasi-LTE discharge, the LTE is based on the above-mentioned criteria.
It defines the plasma. (C) Since it is easy to control the directionality of the active species, it is advantageous for anisotropic etching and the like.

(D) Since the amount of gas required for treatment is small, the manufacturing cost is reduced and the abatement device that is essential for surface treatment but is harmful and dangerous if leaked is small in size. Things get better.

When the apparatus having the magnetic field as described above is used, the apparatus as a whole can be reduced in size and price, and the surface treatment with good controllability can be achieved by expanding the working pressure range in the low vacuum direction.

Next, the reaction chamber 20 of the apparatus shown in FIG. 1 will be described.
The reaction chamber 20 is composed of a reaction container 21 which can be kept airtight if necessary, an introduction ring 22 for introducing a reaction gas provided therein, and a substrate holder 32 for installing a substrate 31. . Between the reaction chamber 20 and the discharge chamber 10, there is a mesh-shaped electrode 14 for introducing the active species 41 or the radiated light 42 from the LTE plasma 5 generated in the discharge chamber 10 to the surface of the substrate 31 of the reaction chamber 20. It is provided. A predetermined reaction gas is introduced into the hollow introduction ring 22 from a flow direction 25 via a valve 24, and is blown to the surface of the substrate 31 through a large number of small holes 23 provided inside the ring, and is introduced into the reaction vessel 21. Supplied. A temperature control 33 is installed on the substrate holder 32, and the temperature of the substrate 31 can be adjusted as necessary.

The introduced gas in the discharge chamber and the reaction gas introduced into the reaction chamber are exhausted in the direction of the gas flow 35 via the valve 34. When the discharge chamber 10 and the reaction chamber 20 are largely communicated with each other, the glow-like plasma spreading around the high frequency LTE plasma often spreads to the inside of the reaction chamber 20 when the pressure is several Torr or less. The above-mentioned mesh-shaped electrode 14 can be provided with an adjusting function such as preventing it or promoting it.

The structure, shape, and material of the electrode 14 are for adjusting the spread of the glow-like plasma into the reaction chamber 20, or for introducing the active species 41 or the radiant light 42 to the surface of the substrate 31 as described above. It does not have to be limited to a mesh-shaped one and the like. Applying a voltage to this electrode 14 enhances the plasma shield effect,
On the contrary, the charged particles can be extracted from the plasma into the reaction chamber 20 and actively used for the surface treatment. It is also possible to install a capacitor having an appropriate capacity between the electrode 14 and the ground potential so that the high frequency serves as the ground potential and the direct current serves as the floating potential. In this case, the abnormal discharge is reduced and the shield effect is increased. Similarly, a bandpass filter may be used between the electrode 14 and the ground potential.

It is also possible to set a magnetic field here instead of the electrode 14 so as to have a similar charged particle adjusting effect.

It is also possible to remove the electrode 14 and positively utilize the glow-like plasma spreading in the reaction chamber 20. The substrate 31 can be placed at a position closer to the LTE plasma 5 than the mesh 14 or inside the LTE plasma 5.

When nitrogen was used as the introduction gas of the discharge chamber 10 and silane gas was used as the gas introduced into the reaction chamber 20 using the apparatus of FIG. 1, a SiN film could be formed on the substrate 31.

The effect of a magnetic field on film formation is 1.98.
˜2.00 SiN film with SiH ₄ flow rate 10 sccm,
When a film is formed under constant film forming conditions (100 Å / min), a high frequency of 13.56 MHz is generated in the absence of a magnetic field.
Although it requires 5 kW, when a magnetic field of about 1000 Gauss is used, a high frequency of 13.56 MHz becomes 0.6 kW.

On the other hand, with the 4.5kW electric power applied with a magnetic field, 10
A film forming rate of 00Å / min was obtained. Using a magnetic field in this way is extremely advantageous for low power consumption or high speed processing.

When hydrogen is used as the introduction gas of the discharge chamber 10 and silane gas or disilane gas is used as the introduction gas of the reaction chamber 20, the a-Si: H film can be formed on the surface of the substrate 31 using the apparatus shown in FIG. It was In this reaction, silane or disilane is decomposed by Lyman series short-wavelength light generated from LTE plasma (hydrogen radicals from LTE plasma play an auxiliary role in this reaction).
It is considered that the formation of the —Si: H film is promoted.

Also in this case, the pale emission of hydrogen changes to red due to the formation of LTE plasma. That is, the blue-white emission of hydrogen molecules is LT
Dissociation by E plasma causes red emission of hydrogen atoms. This red light emission is due to the Balmer series of hydrogen atoms, and the increase in the brightness of the Ballmer series simultaneously shows the increase in the brightness of the Lyman series of vacuum ultraviolet light. Thus, even in the formation of the a-Si: H film, the LT
E-plasma produces a large amount of active species of hydrogen and strong vacuum ultraviolet light, and at least one of them can be utilized to produce a good film.

Further, hydrogen is used as an introduction gas for the discharge chamber 10, and the reaction chamber 2
When silane gas or disilane gas; and germane gas were used as the introduction gas of 0, an a-SiGe: H film could be formed on the surface of the base 31.

Further, hydrogen is used as the introduction gas for the discharge chamber 10, and silane gas or disilane gas is used as the introduction gas for the reaction chamber 20;
And when methane gas is used, a
A SiC: H film could be created.

Conventionally, the a-SiGe: H film and the a-SiC: H film are
It is known that when a film is formed in active hydrogen, a good film can be formed, but in the embodiment of the present invention, active hydrogen can be supplied to the film formation surface, which is a very good quality a-SiG.
An e: H film and an a-SiC: H film could be created.

The above is a-Si: H film, a-SiGe: H film, a-S
Although the effectiveness of LTE plasma was shown for the formation of the iC: H film, the effect of using a magnetic field is also very large in this case.
That is, it is possible to generate active hydrogen and vacuum ultraviolet light by LTE plasma with low power, and it is possible to extend the pressure region of film formation to the low pressure side. Since the mean free path for film formation in the low-pressure region becomes long, active hydrogen can be effectively used and effectively supplied to the film formation surface. Therefore, when using the apparatus of the present invention, it is possible to obtain a very good film quality.

Furthermore, using the apparatus shown in FIG. 1 as well, oxygen is used as the introduction gas of the discharge chamber 10, oxygen radicals, ozone, etc. are created using LTE plasma, and short-wavelength light of oxygen or oxygen radicals or ozone is used. The organic substance on the surface of the substrate can be decomposed into water and carbon dioxide to clean the surface of the substrate. In this case, the gas to be introduced into the reaction chamber 20 is not necessary, and therefore the introduction ring 22 or the like is unnecessary.

Also in this case, it is effective to use a magnetic field to create the LTE plasma, as described above.

Further, using the apparatus shown in FIG. 1, nitrogen trifluoride (NF ₃ ) was used as the introduction gas of the discharge chamber 10 to activate the active species of fluorine as L
By using TE plasma, the Si film or the SiO ₂ film of the semiconductor device can be etched.
Also in this case, the introduction gas of the reaction chamber 20 and the introduction ring 2
2 is not necessary. The effectiveness of the magnetic field is similar.

Next, FIG. 6 shows an apparatus for producing the LTE plasma 5 by capacitive coupling using the doughnut-shaped electrodes 6 and 6'instead of the coil 3 of FIG.

This device also has an a-Si: H film, similar to the device of FIG.
It was effective for forming a-SiGe: H film, a-SiC: H film, ashing using oxygen plasma, surface cleaning, or dry etching of Si or SiO ₂ film using nitrogen trifluoride plasma. . The device of FIG. 1 and the device of FIG. 6 have some differences in impedance matching before discharge, but there is no significant difference in their characteristics after discharge once.

The effectiveness of the magnetic field was similar to that of the device shown in FIG.

FIG. 7 shows an apparatus in which the mesh-shaped electrode 14 of FIG. 1 is removed and processing is performed using glow-shaped plasma diffused from the LTE plasma 5. In this device, several Tor
It is recognized that the glow-like plasma 43 often diffuses from the LTE plasma to the inside of the reaction vessel 21 in the pressure region of r or less, and the glow-like plasma 43 can be used together for various surface treatments.

For example, in the surface treatment in which irradiation of some charged particles is allowed, the glow-like plasma 43 can be used together to increase the surface treatment speed.

For example, in the formation of a SiN film, the apparatus shown in FIG. 7 can obtain a film forming speed about 10 times that of the apparatus shown in FIG. (In fact, it was confirmed that the SiN film was made with a refractive index of 1.98 to 2.00. Although the flow rate of silane was constant, the refractive index of the apparatus shown in FIGS. No comparison can be made simply because the flow rates of silane and nitrogen gas are different.) Similarly, a-Si: H film, a-SiGe: H film, a-S
Also in the film formation of the iC: H film, the apparatus of FIG. 7 is capable of forming a film at a higher speed than that of FIG. Further, it is also effective for ashing using oxygen plasma, surface cleaning, and chemical dry etching of Si, SiO ₂ films, etc. using nitrogen trifluoride.

The effect of the magnetic field is as effective as the device of FIG. 1 or FIG.

FIG. 8 shows an embodiment using microwaves. Reference numeral 7 is a microwave power source, 8 is a waveguide, 9 is a microwave introduction window, and 44 is diffusion plasma diffused from the LTE plasma 5. Four
Reference numeral 5 is an extraction window for narrowing down the diffusion plasma 44.

Here, when the microwave frequency is 2.45 GHz and the magnetic field strength is around 875 Gauss, electron cyclotron resonance (ECR) occurs. In the magnetic field strength near this, L
It is possible to make TE plasma. In the apparatus shown in FIG. 8, even if a single mode microwave power is supplied to the discharge space 15,
Due to the minute changes in the shape and structure of the discharge chamber 10, the discharge chamber 1
Many microwave modes occur inside 0. When the LTE plasma 5 is generated, the microwave mode is further changed by the plasma.

Although a magnetic field is created in the discharge space 15 by the magnet 4, it is very difficult to create a uniform magnetic field strength in the discharge space 15.

As described above, due to the presence of many microwave modes in the discharge space 15 and the fact that the magnetic field is somewhat non-uniform, there are several points at which resonance occurs due to the intensity distribution of the magnetic field. , The spatial positions of the points that cause resonance are different. For the above reasons, the most effective resonance condition depends on the individual device and usually needs to be determined by actual matching.

In some cases, the direction B of the magnetic field may be opposite to that shown in the figure. In this case, although the reason is not clear, it is considered that the microwave reflected by the extraction window 45 and the magnetic field resonate with each other.

In such a device of FIG. 8, it is easy to make an LTE plasma. For example, when nitrogen is used as the introduction gas of the discharge chamber 10, a peak of light emission due to nitrogen atoms dissociated from nitrogen molecules at low power is observed.

In particular, the apparatus shown in FIG. 8 was characterized by dissociation of nitrogen molecules as compared with the embodiment shown in FIG. From the result of the spectroscopic analysis of the light emission from the LTE plasma, the peak split into three in the vicinity of 2p ² ( ³ P) 3p ( ⁴ S ⁰ ) → 2p ² 3s ( ⁴ P) 745 nm due to the nitrogen atom is strongly indicated. It was confirmed that it became very strong. However, in the device of FIG. 8 and the device of FIG. 1, the peaks split into 7 in the vicinity of 2p ² ( ³ P) 3p ( ⁴ P ⁰ ) → 2p ² 3s ( ⁴ P) 821 nm did not change much.

From this, it is clear that in the apparatus of FIG. 8, more 2p ³ ( ³ P) 3p ( ⁴ S ⁰ ) states of nitrogen atoms occur than in the apparatus of FIG. Also, 2p of nitrogen atom
^{2 (3 P) 3p (4} P 0) state, device or of the effect of Figure 1 does not change the amount is too can not be expected.

When nitrogen was used as the introduction gas of the discharge chamber 10 and silane gas was used as the gas introduced into the reaction chamber 20 using the apparatus of FIG. 8, a SiN film could be formed on the base 31. The street in this case device of the FIG. 8 as compared with the apparatus of FIG. ^{1, 2p 2 (3 P) 3p} (4 S 0) is the state there are many, at the time of creation of the SiN film, 2p ² ( ³ P) 3
Since the p ( ⁴ S ⁰ ) state has a short lifetime, the ground state of the nitrogen atom relaxed from this state, that is, 2s ² 2p ³ ( ⁴ S)
It is considered that the condition works effectively.

Other excited states of nitrogen atoms in the LTE plasma created by the apparatus of FIG. 8 have not been analyzed at this time, but relaxed and metastable nitrogen atoms (for example, 2s
² 2P ³ ( ² D) or, for example, 2s ² 2p ³ ( ² P))
There is a possibility that the excitation that causes the occurrence of is also promoted, and in this case, metastable nitrogen atoms also contribute to the formation of the SiN film.

Further, the intensity of vacuum ultraviolet light from nitrogen atoms was also much stronger in the device of FIG.

Regarding the formation of the SiN film, the apparatus of FIG. 7 in which the method of creating the LTE plasma is the same as that of the apparatus of FIG.
When comparing with the device of FIG. 8 using R, the device of FIG. 8 shows more dissociation into nitrogen atoms,
It became clear that the N film can be produced at high speed.

Similarly, using the apparatus of FIG. 8 and using hydrogen as the introduction gas of the discharge chamber 10 and silane gas or disilane gas as the introduction gas of the reaction chamber 20, an a-Si: H film is formed on the surface of the substrate 31. did it.

Even in this case, the dissociation of hydrogen molecules is more effective in the device shown in FIG. 8 as compared with the devices shown in FIGS. 1 and 7, and a large amount of hydrogen atoms and strong vacuum ultraviolet light or either one of them is further added. It can be used effectively.

This hydrogen-based active species is aS
It can be used for forming an i: H film, an a-SiGe: H film, and an a-SiC: H film.

In addition, ashing using oxygen plasma, surface cleaning, surface oxidation, or S using nitrogen trifluoride plasma
Even in the dry etching of i and the SiO ₂ film, the surface cleaning, and the like, the effects of the devices shown in FIGS. 1 and 7 can be obtained.

A device in which the structure of FIG. 8 is slightly modified is also useful.

That is, the extraction window 45 may be removed by a process that does not require narrowing down the diffusion plasma 44, such as surface cleaning of the substrate 31 or dry etching.

Also, instead of the extraction window 45, the electrode 1 of the device of FIG.
You may install the component equivalent to 4. The effect of this electrode 14 can be expected to be the same as that of the device of FIG.

Next, the effect of the magnetic field in the apparatus shown in FIG. 8 will be noted.

When argon is used as the introduction gas in the discharge chamber 10 in the apparatus shown in FIG. 8, 1.5 kW of 2.45 GHz microwave is introduced under the condition of no magnetic field. In this case, the color of argon is red-white. That is, it is the light emission of the atom of argon. However, when the magnetic field strength is increased, LTE plasma formation starts from a certain point and the discharge turns blue. This is the color of argon ions.
By applying the magnetic field, the conversion to LTE plasma proceeded with low power. Normally, even if the magnetic field strength is changed, the color of the LTE plasma 5 only becomes blue (argon is ionized), and the diffusion plasma 44 is still red-white (argon atom).
And there is not much change.

However, in the vicinity of a certain magnetic field strength, the diffused plasma 44 also becomes blue, and it becomes clear that argon ions are extracted to the surface of the base 31. In this respect also, the characteristic near the magnetic field for the device of FIG. 8 appears strongly. As described above, the magnetic field strength that causes the diffused plasma 44 to turn blue has a relationship with the microwave mode, and changes in the minute shape and structure of the device may change subtly. Need to decide.

When methane gas diluted with hydrogen is introduced into the discharge chamber 10 of the apparatus of FIG. 8 under the condition that the ions are effectively supplied to the surface of the substrate 31 by the diffusion plasma 44, the surface of the substrate 31 is coated with the diamond-like carbon film. . It is known that a large amount of active hydrogen and methyl cations are required to form a diamond-like carbon film. The apparatus shown in FIG. 8 is most suitable in this respect, and the active hydrogen generated by the LTE plasma, the diffusion plasma 44 and the methyl cations extracted by the magnetic field are transported to the surface of the substrate 31. Thus, the diamond-like carbon film can be effectively coated using the apparatus shown in FIG.

As described above, the use of ECR conditions has expanded the usefulness of the LTE plasma and opened new avenues for many kinds of surface treatments.

In this embodiment, 2.45 GHz and 875 Gauss were used as the ECR conditions, but in addition, 5.8 GHz and 2071 Gauss,
It is possible to use conditions such as 40.68 MHz and 14.5 Gauss, 27.12 MHz and 9.7 Gauss, and 13.56 MHz and 4.8 Gauss.

Further, instead of the extraction window 45 of the device of FIG. 8 or the electrode 14 of the device of FIG. 1, MgF ₂ , Ca
When a window made of F ₂ , LiF, sapphire, quartz glass, or the like is installed, and the discharge chamber 10 and the reaction chamber 20 are separate vacuum chambers, and gas is introduced and exhausted in each, radiated light from the LTE plasma is used. It is also possible to perform the surface treatment using (in particular, strong vacuum ultraviolet light emitted from LTE plasma).

Next, FIG. 9 shows a surface treatment apparatus according to a third embodiment of the present invention. Reference numeral 30 denotes a discharge reaction chamber, which is composed of a single discharge reaction container 29, and has the functions of both the discharge chamber 10 and the reaction chamber 20 of the apparatus of the second invention described above.
Unlike the second invention, in the apparatus of the third invention, the treated surface of the substrate 31 is in direct contact with the LTE plasma.

In such a device, the short-lived active species produced by the LTE plasma 5 can be effectively utilized, and can be utilized for the high-speed surface treatment of the substrate or the production of the high temperature stabilizing substance. The effect of the magnetic field applied to efficiently create the LTE plasma 5 is the same as in the case of the second invention, and the usefulness of using ECR discharge is also the same as in the case of the second invention.

By using the apparatus of FIG. 9 and introducing diborane gas and ammonia gas diluted with hydrogen from the direction of 13 through the valve 12, a boron nitride film could be formed on the surface of the base 31.

Further, when methane gas diluted with hydrogen is introduced from the direction of 13 through the valve 12 using the apparatus of FIG.
A diamond-like carbon film could be created on the surface of.

Further, using FIG. 9, similarly introducing oxygen gas,
The surface of the base 31 of the silicon wafer was oxidized and a low temperature oxide film could be obtained.

Further, when nitrogen trifluoride was similarly introduced using the apparatus shown in FIG. 9, it became possible to perform high-speed etching of the Si, SiO ₂ film or the like on the surface of the base 31.

FIG. 10 shows an embodiment of the third invention using microwaves. Similar to FIG. 8, the strength of the magnetic field can be changed and ECR discharge can be performed.

The effect of the magnetic field is similar to that of the apparatus shown in FIG. 8, and the surface treatment similar to that shown in FIG. 9 can be realized more effectively.

In the embodiment shown in FIGS. 1 to 10, a mirror type magnetic field may be used instead of the magnetic field shown here, or both may be used in combination.

Furthermore, a bias of DC, AC or RF may be used in combination with the base 31 and / or the base holder 32. In this case, a film with good step coverage was obtained during film formation, and planarization was possible depending on the conditions. Further, there is an advantage that anisotropic etching can be obtained during etching.

(Effects of the Invention) The present invention enables stable production of high-purity strong synchrotron radiation and / or active species at low power, and by using this, high-speed and high-quality surface treatment can be performed. There is an effect that a surface treatment method and apparatus can be provided.

[Brief description of drawings]

FIGS. 1, 6, 7, and 8 are front sectional views of embodiments of the first and second inventions of the present application. FIG. 2 is a diagram showing the relationship between the injection power and the emission intensity of the LTE discharge of hydrogen. FIG. 3 is a graph showing the results of vacuum ultraviolet emission spectroscopic analysis from LTE plasma. FIG. 4 is a graph showing the results of vacuum ultraviolet emission spectroscopic analysis from glow plasma. FIG. 5 is a graph showing the relationship between the injection power of nitrogen LTE discharge and the emission intensity. 9 and 10 are front sectional views of the first and third embodiments of the present invention. 1 ... Power supply, 3 ... Coil, 4 ... Magnet, 5 ... LTE plasma, 7 ... Microwave power supply, 10 ... Discharge chamber, 11 ... Discharge tube, 15 ... Discharge space, 20 ... Reaction chamber, 21 ... Reaction vessel, 29 ... Discharge reaction vessel, 30 ... Discharge reaction chamber, 31 ... Substrate, 32 ... Substrate holder.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kim Kyoue 5-8-1 Yotsuya, Fuchu-shi, Tokyo Nichiden Anelva Ltd. (72) Koji Noma 5-8-1 Yotsuya, Fuchu-shi, Tokyo Tokyo Anel Ba Incorporated (72) Inventor Shinji Takashiro 5-8-1 Yotsuya, Fuchu-shi, Tokyo NIDEC ANELVA Incorporated Sadao Kinashi (56) Reference JP 61-222534 (JP, A) JP Sho 61-166976 (JP, A) JP-A-54-83376 (JP, A) JP-A-55-23085 (JP, A) JP-A-59-159167 (JP, A) JP-A-54-35172 (JP, A) A)

Claims (6)

[Claims] 1. An LTE discharge is generated by introducing a predetermined gas into a space to which alternating electric power is applied, and the LT discharge is generated.
A surface treatment method for performing a predetermined treatment on the surface of a substrate placed in or near the LTE discharge by introducing at least one of synchrotron radiation generated by plasma of E discharge and active species. A surface treatment method, wherein the LTE discharge is created or maintained in a magnetic field. 2. The surface treatment method according to claim 1, wherein the magnetic field has a magnetic field strength in the vicinity of where ECR resonance occurs. 3. A discharge chamber having a reaction chamber containing a gas to be treated, an alternating power source, a discharge chamber to which an alternating power of the power source is applied by inductive coupling, capacitive coupling or cavity resonance, and the discharge. A means for introducing a predetermined gas into the working space, and an irradiation means for guiding at least one of radiant light and active species generated in the LTE discharge of the discharge space to the surface of the substrate to be treated in the reaction chamber. A surface treatment apparatus comprising a magnetic field generation mechanism capable of setting a magnetic field in the discharge space. 4. The surface treatment apparatus according to claim 3, wherein the magnetic field generating mechanism creates a magnetic field strength in the vicinity where ECR resonance occurs. 5. An alternating power supply, a discharge treatment chamber having a discharge space to which alternating power of the power supply is applied by inductive coupling, capacitive coupling or cavity resonance, and a predetermined gas is introduced into the discharge space. Means for accommodating a substrate to be treated in the LTE discharge of the discharge space,
A surface treatment apparatus for treating the surface of a substrate to be treated, comprising a magnetic field generation mechanism capable of setting a magnetic field in the discharge space. 6. The surface treatment apparatus according to claim 5, wherein the magnetic field generation mechanism creates a magnetic field strength in the vicinity where ECR resonance occurs.