JPH0320468A - Microwave treating device having magnetic field - Google Patents

Abstract

PURPOSE:To stably form a high quality reaction-formed film at a uniform thickness on a large-area substrate with the microwave treating device having a magnetic field by forming a space closed in terms of electromagnetic energy in the reaction chamber of the device into which microwaves are introduced. CONSTITUTION:The substrate 1 is mounted to a holder 13 and is disposed in the reaction chamber 19. Methyl alcohol or the like as a reaction gas is introduced with gaseous H2 as a carrier gas into the reaction chamber 19 from gas system 10. The microwaves of, for example, 2.45GHz frequency are released from a microwave oscillator 18 into the reaction chamber 19. The effect of external magnetic fields 17, 17' and the spacing 28-1 between the outside insulating part of the holder 13 and the inside wall of the reaction chamber are confined to <=1/4 the wavelength of the microwaves, by which the hermetic space to the microwave energy is formed in the reaction chamber 19 and the plasma density of the reaction gas in the reaction chamber is increased. The C formed by the cracking of the methyl alcohol on the surface of the substrate 1 is formed as a diamond crystal layer of a uniform thickness on the substrate 1.

Description

[Detailed Description of the Invention] "Field of Application of the Invention" The present invention relates to a magnetic field microwave processing device,
It is used as a CVD device or etching device. ``Prior art'' Conventionally, as a microwave processing device, the ion shower device if (Unexamined Japanese Patent Application [57-133636] by Seitaro Matsuo
, JP-A-55-141729) is known. This is known as an ECR (electron cyclotron resonance) processing device that uses a divergent magnetic field. An example of this is shown in Figure 2, in which microwave energy is guided into the plasma growth chamber (19) through a waveguide (34) and a magnetic field (17) is applied there. This plasma is closed by an orifice (31) and has a plasma extraction window (32) in its center. A magnetic field is emitted at a distance of 20 to 30 cm from here (29), and the holder (
13) A substrate (1) is disposed thereon. That is, the substrate to be treated is placed in the reaction chamber (33) located away from the plasma generation chamber, and the gas has a long mean free distance of 0.0
Under a low pressure of 0.3 torr or less, plasma emitted from a plasma extraction window is guided onto a substrate by a magnetic field (29) to perform a predetermined process. That is, a plasma generation chamber (19) was treated as an open space for microwave energy and reactive gases.The applicant has also proposed many Cv-ro devices as magnetic field microwave Cv-ro devices.However, this microwave output' is Up to 0.5KW at most,
In order to supply strong energy of 2~IOK- to the substrate and perform plasma processing, a technical proposal for a method that actively creates a substantially closed space for microwave energy and provides an interspace for reactive gases is proposed. There wasn't.

Furthermore, in the magnetic field microwave etching method, the present applicant has developed a method in which direct current or high frequency bias is applied for etching. (Tokuko Showa 63-44827
(filed on October 14, 1985) However, in this invention, microwaves are confined in the closed space proposed by the present inventor, high-density plasma is generated there, and anisotropic etching is actively applied to the upper surface of the substrate. No method is shown.

``Problems with the prior art'' As an electronic device, a typical CV that requires magnetic field microwave energy that requires high-energy plasma density.
As an application of the D film, an example of forming a diamond film is known. It is necessary to form this diamond coating uniformly over a large area with a uniform thickness and at a high speed.

As a conventionally known method, there is a method using a magnetic field microwave CVD apparatus. In this case, when strong microwave energy is supplied, the reactive gas supplied to the cylindrical reaction chamber is turned into plasma, and much of this reactive gas is released into the exhaust system, resulting in a loss of microwave energy. I urged her. For this reason, ECR using a divergent magnetic field
In this method, there was no technical concept of confining microwave energy in a closed space and using the space as a reaction chamber to supply strong microwave energy onto the substrate.

Also, this release rP1. In the magnetic field method, in the CvD method, the thickness of the membrane is different between the central part and the peripheral part. Further, if etching is performed, the precision of the fine pattern deteriorates in the peripheral area, and vertical etching is impossible.

``Object of the Invention'' The present invention relates to a magnetic field microwave processing device that eliminates such drawbacks.

Using a magnetic field microwave CVD device or a magnetic field microwave etching device, it is possible to form a high-quality film with a uniform thickness over a large area and at a high deposition rate.

Furthermore, even in plasma etching of fine patterns with a width of 1 μm or less, the pattern is intended to be cut uniformly at the periphery and center of the circular substrate.

The application thereof is not only to simply form diamond using the CVD method, but also to a high-speed submicron magnetic field bias plasma etching method.

``Structure of the Invention'' The present invention provides a magnetic field microwave processing device in which a reaction chamber into which microwaves are introduced is a closed space or a substantially closed space for electromagnetic energy, and at the same time an interspace for reactive gases. It is for the purpose of

The reaction chamber of the present invention has a configuration in which the plasma feeding chamber and the reaction chamber in the conventional example are integrated.

Therefore, the holder for holding the substrate has approximately the same shape and its dimensions are slightly smaller than the inner diameter of the reaction space. The distance between the inner wall of the reaction space and the holder was set to 174 wavelengths of microwaves or less.

As an application of the present invention, in the CVD method, unnecessary gases after the reaction are released to the outside, while the reaction products are formed on the processed surface of the substrate with the same thickness at the periphery and the center and with high quality. This is what I wanted to warn you about. A typical example is the electromagnetic field closed space type diamond membrane device.

In the case of magnetic field etching, conventional E etching using a divergent magnetic field is also used.
0.01-10t with pressure more than one order of magnitude higher than the CR method
The etching rate is increased by 5 times or more as orr, and it is possible to perform sub-certain pattern patterning.

In the present invention, the reaction space has a cylindrical shape, microwave energy is supplied from one end of the cylinder, and a holder having a processing surface is provided at the other end, facing each other (
(to oppose). The holder and the reaction chamber have approximately the same shape and are slightly smaller in size, so that the microwave energy is not released to the outside (rearward) through the gap between them.
Unnecessary reactive gases are released as neutral gases by extinguishing the plasma state. The interval is 1 microwave wavelength
74 or less, the average flow velocity when the gas is made into a laminar flow in the reaction space can be in the range of 5 to 600 cm/sec, preferably 20 to 200 cta/sec, and the reaction pressure can also be 0.03 to 10 torr. As a result, it is now possible to supply microwave energy to effectively convert reactive gases into plasma.

The present invention will be described below according to examples.

"Example 1" In the present invention, an outline of a magnetic field microwave processing apparatus is shown in FIG.

A substrate (1) having a processing surface disposed on a holder (13).
) was installed in a magnetic field microwave plasma CVD apparatus (hereinafter also simply referred to as plasma CVD apparatus).

This plasma CVO device has 1 to 5 Gllz, for example 2
．． Using a frequency of 45 Gllz (wavelength 12.25 cm), the reaction chamber (19) has a cylindrical shape, and its inner diameter is 170 cm.
It has mm.

In the gas flow (20) in the direction of the arrow, the average flow velocity is assumed to be a laminar flow inside the container, and is shown as a value obtained by dividing the total supply gas flow rate by this inner diameter area. This microwave energy can be up to 10κ
up to W, microwave oscillation H (18), attenuator (
16). It can be added to the reaction chamber (19) through the quartz window (15). In addition, Helmholck coils were used in the magnetic fields (17) and (17') to create a resonance surface of 875 Gauss on or near the substrate.

Inside the reaction chamber (19) is a 2 to 6 inch, typically 4
An inch circular substrate (1) was placed in a holder (13) while being held down by a substrate presser (14).

The outer diameter of the holder (13) (here 140 mm) is 1 of the wavelength (λ) as shown in (2B-1) with respect to the inner diameter of the reaction chamber.
74 (equivalent to 30.6mm) or less 3-30
IIIl, for example, 15 mm. Holder thickness (
2B-2) was set to 10 to 50 mm. It is a quartz window〈I
5) The microwave introduced from this gap (28-1)
This is to prevent it from leaking further backwards and being wasted without being involved in the reaction.

Thus, the reaction chamber has a cylindrical shape, and the reaction space is substantially closed for microwaves by the cylindrical substrate holder (after the reaction, unnecessary gas collides with the inner wall or the holder and is neutralized, and this gap ( 28-1) to the rear exhaust system) and the introduced microwave reaction chamber (1).
9), it is possible to obtain good resonance and to reduce reflection to 5χ or less. Further, since the reaction chamber and the holder are both of the same shape and concentric (same center), the optimum position for film formation within the reactor can be adjusted by the substrate position moving mechanism (12).

The exhaust system consists of a valve (25) that serves as a pressure adjustment valve and a stop valve, a wide area turbo molecular bomb (26), and a roughing pump (27). Since a turbo-molecular pump is used, the gas flow rate in the reaction vessel is set to 0. 6 at Itorr
It was possible to increase the speed to 0 cm/sec. Pressure adjustment valve (
25), the flow rate (20) in the reaction chamber (19)
5 to 600ca+/sec, especially 20 to 2
00 cm/sec was optimal.

Furthermore, the initial evacuation was performed to 10-' to 10-' torr using a wide range turbo molecular pump.

After this, for these, the doping system (21). (2
2) , (23) . Reactive gas using (24),
Carrier gas was introduced.

The size of the holder (13) is 1 from the outer diameter of 140mm φ.
An experiment was conducted by replacing the diameters of 20fflmφ, loo■φ, and 80mmφ.

This time interval (2B-1) is 15n+m. 25mm,
It becomes larger at 351mm and 45mm. But l/4
When the distance exceeds λ (30.6 mm), it becomes difficult to adjust the attenuator and it becomes impossible to effectively introduce the microwave output into the reaction gas. This resulted in different process conditions.

"Example 2" This example is a case where a film was formed using the plasma CVD method using Example 1. That is, the inner diameter of the reaction chamber l70n+mφ
, when the holder outer diameter is 140 mmφ and the interval is 15llII+. As this coating, we supplied high microwave energy to form an effective diamond film that can be formed at high speed. Methyl alcohol (CHU011) from doping system
) or alcohol (22) such as ethyl alcohol (CJsOFl) with 40 to 200 volumes of hydrogen (21) at a concentration of IOOCC/min! (100 volumes χ corresponds to the same amount of hydrogen) and introduced. A 4-inch silicon wafer was used as the substrate. The pressure during film formation is 0.03 to 3 torr, typically 0.1 to 1 torr, for example Q. It was set to 25 torr. 2
．． A magnetic field of 2KG (kilogauss) was applied so that the magnetic field at or near the substrate was 875 gauss. A frequency of 2.45 GIIz was used for the microwave, 2 to IOKW was added as the microwave pressure, and the temperature of the substrate was raised to 200 to 1000°C, for example 800°C, by the electromagnetic energy of the microwave itself. If the heating was insufficient, the holder was auxiliary heated to bring it to the appropriate temperature. The carbon in the alcohol, which is decomposed and turned into plasma by this microwave energy, grows on the substrate, making it possible to make a single-crystal diamond (which has the shape of a diamond). At the same time, in addition to this diamond, some graphite is also present, which reacts with the 011 group present in the active gas and revaporizes as carbon dioxide or methane gas, resulting in crystallized carbon, that is, diamond. 5-5
For example, with an average thickness of 1.3 μm (duration time of 2 hours), it was possible to perform a ceremonial process 10 to 30 times faster than the conventional ECR method.

When the crystallinity of the coated diamond was investigated by laser Raman spectroscopy, it was found that 1336C51-
A sharp peak was observed at the wave number of ', and the wave number of 1490 cm-' for the graphite component was hardly detected. For the first time, it has been discovered that extremely high quality (SP, bond only) diamonds can be produced. Moreover, the film thickness of the entire 54-inch wafer was within ±5% on average, and had particularly excellent uniformity.

Example 3 This example uses the apparatus shown in Figure 1 as a magnetic field microwave plasma etching apparatus. 2.45G}
A microwave of 1 to 8 kW was applied from an Iz microwave (18). The doping system is nitrogen (21), SF6 (2
2) , CI3rF 3 (23) , CBr 4
(24). For example, CBrF3 and SF. Process: 1
and 40 cc/min of each was supplied. The pressure is 0.
It was set to 05 torr.

The substrate is a 4-inch silicon substrate, with a 0.3μ
A pattern with m pitch was formed using photoresist. Direct current or high frequency bias (8
) was added simultaneously with the microwave energy. To cool the substrate, the holder was cooled to 0"C or lower.

Then, in addition to this high frequency (13.56 KHz) bias, a DC self-bias of -too to -200 V was applied to obtain an etching rate of 0.9 μm/min.

Further, it was possible to obtain anisotropy accuracy=(horizontal distance between the upper end and the lower end after etching)/(etching rate) of 0.05 or less.

In this way, by using a photoresist pattern with a small pitch of about 0.3 μm as a mask, it was possible to obtain sharp etching recesses for trench structures in the underlying silicon.

2 umI min at pressure 0.1 torr, 1 min at l torr
An extremely high etching rate of 23 μIll was achieved at 0 am/min and 5 torr. Even though such a high etching rate was obtained, the anisotropy accuracy did not improve much (0.1, 0.2, 0.4), but the central part of the silicon substrate and the peripheral part (peripheral edge 5 more
There was almost no difference in the pattern cutout (etching speed, anisotropy accuracy) or the pattern cutout (etching rate, anisotropy accuracy).

If the outer diameter of the holder is made smaller and the gap (28-1) in Figure 1 is set to 40 mm and is larger than 1/4 λ, the plasma will flow out to the rear of the holder, resulting in pattern breakage at the periphery. It got worse.

"Effect" In the magnetic field microwave processing apparatus of the present invention, the reaction chamber is a closed space or a substantially closed space, and strong microwave energy is supplied thereto, so that the plasma density in the reaction space can be extremely increased. can. As a result, even materials that are extremely difficult to handle using the CVD method, such as diamond, could be coated uniformly and homogeneously over a large area.

This certain film is not diamond, but BN, BP, S.
iJ4 or other materials may be used.

Furthermore, when using a plasma etching apparatus instead of the CVD method, other etching gases such as high concentration CBr.
The device of the present invention is effective even when used for high-speed etching of superconducting materials, metals, semiconductors, and insulating films. In particular, when attempting to selectively etch submicron fine patterns, the pressure in the reaction chamber becomes high and vertical input must be applied to the substrate by applying a bias.

In order to effectively activate the reactive gas, creating a closed space was effective in increasing the degree of anisotropy and increasing the etching rate.

In the present invention, the reaction chamber was cylindrical. However, it goes without saying that even a rectangular shape may be designed so as to resonate with the magnetic field. The holder in that case was also made into the same rectangular shape.

[Brief explanation of the drawing]

Figure 1 shows an outline of the magnetic field microwave plasma processing apparatus of the present invention. FIG. 2 shows a conventional device. FIG. 3 shows laser Raman spectroscopy data of diamond produced according to the present invention. 1 . . . 8 . . . 17.17'・ ・ ・ ・ ・ ・ 26. . . . . . . 27.

Claims (2)

[Claims] 1. means for supplying microwave energy to the reaction chamber;
means for supplying a magnetic field to the reaction chamber from the outside in order to cause the reaction chamber to have a resonance region; means for introducing a reactive gas into the reaction chamber; and opposing means for supplying microwave energy to the reaction chamber. and a holder for disposing a substrate having a processing surface, the outer shape of the holder having approximately the same shape as the inner diameter of the reaction chamber, and a space between the inner wall of the reaction chamber and the holder. By providing a closed space or a substantially closed space that prevents the microwave energy from being released from the reaction chamber to the outside, waste of the reactive gas is removed from the space between the holder and the inner wall of the reaction chamber. A magnetic field microwave processing device comprising a means for discharging. 2. A magnetic field microwave processing apparatus according to claim 1, wherein the distance between the outer shape of the holder and the inner wall of the reaction chamber is 1/4 of the wavelength of the microwave or less.