JPH0474433B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for forming a nitride film on a substrate surface by vapor phase growth using interaction between cyclotron resonance and an electric field. be.

[Conventional technology]

Thin film formation technology using gas-phase reactions includes optical CVD, which activates reactive gases with light energy, and thermal
CVD method, plasma CVD method, etc. are known.

Further, known physical thin film forming techniques using solids as starting materials include vacuum evaporation, sputter evaporation, and ion evaporation.

[Problem to be solved by the invention]

However, each of the above thin film forming techniques has advantages and disadvantages, and is inexpensive and not suitable for mass production.

The above photo-CVD method does not use an electric field, so it can form a film well, but the film growth rate is 0.1~
It is slow at 0.5 Å/sec and is not suitable for mass production.

Furthermore, although the thermal CVD method can produce large quantities, it requires lowering the substrate temperature to nearly 500°C, and is likely to be limited by the type of substrate.

In addition, the nitride film has a slow diffusion rate of nitriding species and is likely to entrain oxygen.

Therefore, it was not possible to obtain a good quality nitride film.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a method for forming a nitride film with a high nitride film formation rate.

Another object of the present invention is to provide a method for forming a nitride film that can obtain a nitride film of good quality.

[Means to solve the problem]

In order to achieve the above object, the method for forming a nitride film of the present invention includes a reaction chamber 1 for forming a nitride film on the surface of a substrate, and a reaction chamber arranged such that the reaction chamber is long in the direction perpendicular to the surface of the substrate 10. a cyclotron resonance space 2 protruding from the reaction chamber 1;
A nitride film forming method for forming a nitride film on the surface of a substrate 10 by simultaneously using energy obtained by cyclotron resonance and an electric field, wherein the nitride film is activated by the cyclotron resonance space 2. The inert gas and/or non-product gas is supplied from a direction perpendicular to the film forming region, and in the reaction chamber 1, the activated inert gas and/or non-product gas is supplied to the film forming region. An electric field is vertically applied to the substrate 10 and the reactive gas mixed with the product gas supplied from the vertical direction, and the atmosphere in the reaction chamber 1 is maintained in a pressure range of 0.03 to 0.001 torr by a turbo pump. Seshime,
A film is formed on the surface of the substrate 10.

Moreover, in the nitride film forming method of the present invention,
The gas to be activated is selected from at least one of an inert gas, nitrogen, or a non-product gas consisting of a nitrogen compound.

Furthermore, in the nitride film forming method of the present invention, the product gas is selected from at least one of silane, disilane, silicon fluoride, a titanium compound, an aluminum compound, and a mixture of the above compound and ammonia.

[Effect]

The cyclotron resonance space projects from the reaction chamber so as to be long in the direction perpendicular to the surface of the substrate on which the nitride film is to be formed.

In the microtron resonance space, the inert gas and/or non-product gas is
A plasma consisting of gas or electrons is generated and activated by the magnetic field and microwaves from an air-core coil wound around the cyclotron resonance space.

The inert gas and/or non-product gas activated by this cyclotron resonance space is introduced into the reaction chamber, mixed with the product gas, and imparts its energy to the product gas.

The product gas energized in this way is further activated by an electric field applied perpendicular to the substrate held in the reaction chamber.

Then, the reactive gas activated by the cyclotron resonance and the electric field is attached to the substrate surface to form a film.

The activated gas is selected from at least one of an inert gas and a non-product gas consisting of nitride, and the product gas is selected from one of silane, disilane, silicon fluoride, a titanium compound, and an aluminum compound. and a mixture of the above compound and ammonia.

In order to improve the quality of the film formed from the above-mentioned inert gas, non-product gas, or product gas, the pressure in the reaction chamber is adjusted to a state of 0.03 to 0.001 torr by a turbo pump. It is done by doing.

Generally, since an oil diffusion pump is used as a vacuum pump for evacuation of the reaction chamber, unnecessary oxygen or carbon remains in the nitride film in the reaction chamber. However, by using a turbo pump in conjunction with a vacuum pump to exhaust the reaction chamber in the nitride film forming method of the present invention, unnecessary oxygen or carbon can be removed when forming a nitride film.

〔Example〕

A method for forming a nitride film on a substrate surface, which is an embodiment of the present invention, will be described.

In the cyclotron resonance space, for example, when argon, which is typical as an inert gas, is added, the magnetic field that causes cyclotron resonance due to this mass and frequency (for example, 2.45 GHz) is 875 Gauss.

In this state, argon is turned into plasma and activated in the cyclotron resonance space.

Other inert gases include helium, neon, and krypton.

Nitrogen or nitrogen compound gases that serve as non-product gases include nitrogen (N ₂ ), ammonia (NH ₃ ), hydrazine (N ₂ H ₄ ), fluorinated carbon (NF ₃ , N ₂ F ₆ ),
Alternatively, a gas mixture of these with carrier gas or hydrogen is typical.

A product gas (a gas that decomposes or reacts to produce a solid) is used as the reactive gas.

The titanium compound that becomes this product gas is Ti
(CH ₃ ) ₄ , Ti(C ₂ H ₅ ) ₄ and TiCl ₄ are representative examples.

Furthermore, it is also effective to add other product gases such as B ₂ H ₆ , BF ₃ , PH ₃ , AsH ₃ and other doping gases to the product gas as additives.

These product gases are activated by colliding with argon, which is activated by interaction with electric and magnetic fields. Additionally, the argon activated by the cyclotron resonance space is mixed with the product gas in the reaction space, transferring excitation energy from the activated argon to the product gas.

As a result, the product gas, which has received an extremely large amount of electromagnetic energy, actively reacts with the non-product gas, making it possible to activate and react almost 100%. In addition, the product gas can retain its energy as intrinsic activation energy rather than kinetic energy.

Further, the method of the present invention can form a nitride film on the surface of the substrate by heating the substrate at a temperature of room temperature to 500°C.

Hereinafter, a specific embodiment of the present invention will be described with reference to FIG.

Embodiment 1 FIG. 1 shows an outline of an interaction type plasma CVD apparatus using cyclotron resonance and an electric field according to the present invention.

In FIG. 1, the cyclotron resonance plasma CVD apparatus includes an exhaust system 11 that lowers the pressure inside a reaction chamber 1, a main body 12 that forms a film on a substrate, and a doping system 13 that dopes product gas or non-product gas. , 13'.

The inside of the stainless steel container 1' in the main body 12 is
A reaction chamber 1 serving as a reaction space is formed. A reaction chamber 1 made of a stainless steel container 1' is provided with a substrate holder 10' on one side (for example, the upper part) for holding the substrate 10 with the film forming surface facing downward.

Further, a halogen lamp heater 7 is provided on the opposite side of the film forming surface of the substrate 10, and the substrate 10 is heated by being irradiated with infrared rays from the halogen lamp heater 7 through a quartz window 19.

Further, the stainless steel container 1' has a lid 1'', a halogen lamp heater 7 is provided on the back side of the lid 1'', and a substrate 1'' is provided.
0, the lid 1'' can be opened upward.

Further, the non-product gas is supplied from the doping system 13 via the introduction pipe 18 to the cyclotron resonance space 2, which is an activation space made of a quartz tube 29, together with an inert gas such as argon. This cyclotron resonance space 2 consists of a thin tube that projects from the reaction chamber 1 so as to be long in the vertical direction with respect to the surface of the substrate 10. Air-core coils 5, 5' are wound around the outer periphery of the cyclotron resonance space 2. By passing a current through the air-core coils 5, 5', a magnetic field is applied to the inert gas or non-product gas.

At the same time, a microwave of 2.45 GHz, for example, is supplied to the cyclotron resonance space 2 from a microwave oscillator 3 via an analyzer 4.

Assuming that the gas that causes cyclotron resonance is argon, a magnetic field determined by the mass of argon and the frequency of microwaves is generated in the cyclotron resonance space 2 by the air-core coils 5 and 5', for example.
875 Gauss is applied.

Therefore, the argon gas is excited, pinched by the magnetic field, and at the same time causes cyclotron resonance, and also collides with the non-product gas in this cyclotron resonance space 2, sufficiently exciting it. Thereafter, the excited argon gas is introduced into the reaction chamber 1 together with the non-product gas and is emitted 21 in a direction perpendicular to the substrate surface.

In the reaction chamber 1, the product gas is in the doping system 1.
The liquid is discharged 22 through an inlet pipe 16 at 3' and a plurality of nozzles 17.

As a result, in the reaction chamber 1, the product gas and the non-product gas are mutually excited and activated.

Furthermore, in the reaction chamber 1, a reactive gas consisting of an inert gas, a non-product gas, and a product gas is supplied to a pair of electrodes 20, 20' provided on the back side of the film forming substrate 10 and near the nozzle 17. An electric field is applied by.

In addition, the reactive gas is sufficiently expanded in the reaction chamber 1, and in order to be activated, the pressure between the reaction space and the cyclotron resonance space 2 is set to, for example, 0.03~
It was set to 0.001torr. This pressure was achieved by adjusting the displacement of the vacuum pump 9 using a turbo pump together with the control valve 14 of the exhaust system 11.

Generally, for evacuation of the reaction chamber 1, an oil diffusion pump (not shown) is used as the vacuum pump 9. Since oil diffusion pumps use oil, unnecessary oxygen or carbon remains in the nitride film in the reaction chamber.

However, in this embodiment, oxygen or carbon can be prevented from entering the reaction chamber 1 by using an oil diffusion pump and a turbo pump (not shown) together as the vacuum pump 9.

That is, the exhaust from the exhaust port 8 using the turbo pump (not shown) can suppress back diffusion of oxygen, carbon, etc. from the exhaust system 11, and reduce the amount of unnecessary oxygen and carbon in the nitride film. I was able to do that.

Furthermore, by forming the electrode 20 that applies an electric field to the reactive gas into a net shape, the effect of a homogenizer that diffuses the reactive gas can also be used.

Therefore, the activated inert gas and non-product gas released from between the electrodes 20 and the product gas released from the nozzle 17 are separated from each other in the reaction chamber 1.
Since the mixture can be uniformly mixed in a wide space, a nitride film with a uniform thickness and a large area is formed on the surface of the substrate 10.

However, the gas activated by the cyclotron resonance space 2 collides with the electrode 20, and the energy there is consumed. Therefore, the growth rate of the film formed on the surface of the substrate 10 decreases. Therefore, if it is desired to obtain a film thickness at a high growth rate, it is sufficient to sacrifice the uniformity of the film thickness and use a mesh electrode having large openings, which is not effective as the homogenizer.

In the reaction chamber 1, unnecessary gas that is not used for the coating formed on the surface of the substrate 10 is exhausted by the exhaust system 11 from the exhaust port 8 in the peripheral area.

Further, the net-shaped electrode 20' provided on the opposite side of the film forming surface of the substrate 10 and the net-shaped electrode 20 provided at the lower part of the reaction chamber 1 are connected to a power source 6.
A high frequency electric field of 13.56MHz or a DC electric field was applied.

At this time, the substrate 10 is positioned perpendicular to the electric field as shown in FIG.

Experimental Example 1 This experiment is an example in which a titanium nitride film was formed on a substrate surface using an interaction type plasma CVD apparatus using cyclotron resonance and an electric field as shown in FIG.

That is, in the cyclotron resonance space 2 with a pressure of 0.003 torr, there is 50% argon in addition to the non-product gas.
It is supplied from the inlet tube 18 at cc/min. Furthermore, titanium tetrachloride is supplied from the introduction pipe 16 at a rate of 20 c.c./min. The microwave is from microwave oscillator 3 with a frequency of 2.45GHz and an output range of 30 to 500W, especially 200W.
was adjusted. The magnetic field applied to the cyclotron resonance space 2 was 875 Gauss by the air-core coils 5, 5'.

In addition, ammonia, which is a non-product gas, was supplied from the inlet pipe 18 in an amount five times that of titanium tetrachloride.

When the ammonia is added through the introduction pipe 18, there is a method in which this ammonia is used as the activated gas, or a method in which argon mixed at the same time as this ammonia is used as the activated gas.

However, in practice, it is appropriate to use argon as the activation gas. That is, the argon is excited by microwaves and a magnetic field, and the electrons and the excited argon collide with the ammonia in the same cyclotron resonance space 2, sufficiently activating the ammonia.

Therefore, the mixed gas of titanium tetrachloride, which is a product gas, and ammonia, which is a non-product gas, can be completely activated in the reaction chamber 1 in cooperation with the electric field.

Furthermore, the product gas supplied from the inlet pipe 16 may be titanized fluoride or carbide in addition to the above.

By using the titanide, the growth rate for forming a nitride film on the substrate surface could be set to 40 Å/sec. Using the above titanide, plasma CVD
The growth rate for forming a nitride film on the substrate surface using only this method was 1.5 Å/sec. That is, the nitride film formed on the substrate according to the above example could be obtained at a growth rate more than 10 times that of the case where it was formed only by the plasma CVD method.

Thus, the wrapping around the recess was also excellent.

When the titanium nitride coating obtained in this example is formed on the surface of a metal tool, the mechanical strength thereof is improved.

Experimental Example 2 Experimental Example 2 is an example in which a silicon nitride film was produced using the apparatus of Experimental Example 1. That is, in the case of Experimental Example 2, the amount of ammonia, which is a non-product gas, introduced through the introduction pipe 18 is five times the amount of silane introduced through the introduction pipe 16.

There is a method of mixing argon in addition to the above-mentioned ammonia as the non-product gas added through the introduction pipe 18.

When the above-mentioned argon is used as a resonance gas, this argon is excited, and the excited argon and electrons collide with annimore in the same resonance space 2,
Activate this ammonia sufficiently.

Therefore, the mixed gas of silane or disilane and ammonia, or silicon fluoride, nitrogen, and hydrogen introduced from the introduction pipe 16 obtains energy from the activated ammonia and is completely activated.

The silicon nitride films formed on the formation surface in this case had growth rates of 16 Å/sec, 27 Å/sec, and 27 Å/sec, respectively. Under the above conditions, if only the conventional plasma CVD method is used, the silicon nitride film will be
The growth rate was only 1.5 Å/sec, which was more than 10 times faster.

The substrate 10 is a silicon substrate (N type 4×10 ¹⁵ cm
^-3 ), the interface states are 8×
10 ¹¹ cm ⁻² , 9×10 ¹¹ cm ⁻² and 8×10 ¹¹ cm ⁻² were obtained.

This value is the same as that for conventional plasma CVD method only.
This value was reduced to 1/3 compared to 1.5×10 ¹² cm ⁻¹ and was almost the same as 8×10 ¹¹ cm ⁻¹ when fabricated using only cyclotron resonance.

In order to further reduce the number of interface states, a silicon nitride film of 50 to 200 Å is formed in advance on the surface to be formed using the optical CVD method.
A two-stage film forming method may be used in which microwaves are continuously applied to the resonance chamber 2 to perform cyclotron resonance plasma CVD.

Experimental Example 3 Experimental Example 3 is an example in which an aluminum nitride film was formed on a substrate surface using an interaction type plasma CVD apparatus using cyclotron resonance and an electric field as shown in FIG.

With the frequency of the microwave oscillator 3, magnetic field, and electric field applied in the same manner as in Experimental Example 1, methyl aluminum (Al(CH ₃ ) ₃ ) was introduced into the inlet tube as a product gas instead of ammonia and titanide gas. 16 and is supplied to the reaction chamber 1 from a nozzle 17. Further, ammonia is supplied to the cyclotron resonance space 2 along with argon from the introduction pipe 18.

In this condition, the surface of the substrate has 4000
A film of aluminum nitride with a thickness of 1.5 Å could be formed in a 10 minute deposition period.

Aluminum nitride (AlN) has been effective as a final packaging film in VLSI because it has high thermal conductivity. The coating properties of the aluminum nitride AlN obtained by the above method were almost the same as those of silicon nitride.

As is clear from the above explanation, the damage to the coating surface on the substrate surface is extremely small, and in order to produce a high-quality coating of arbitrary thickness, the interaction between cyclotron resonance and electric field is combined with non-product gas. It is used for product gas. Therefore, in the formation of an insulating film, the insulation properties can be further improved, and a higher film growth rate can be obtained.

Further, since the exhaust system 11 is evacuated using a turbo pump, the reaction chamber 1 can form a nitride film on the substrate surface in a state where back diffusion of oxygen and carbon from the vacuum pump 9 is reduced.

In this example, NF ₃ , H ₂ , and N ₂ O were introduced through the nozzle 17 in FIG. 1 as a pre-process for film formation.
When the surface of a semiconductor device is photocleaned or plasma cleaned, reproducibility between batches is improved. In this photo cleaning or plasma cleaning, the surface of the semiconductor may be cleaned not only with active hydrogen but also with fluorine or chlorine to remove oxides and dirt.

Semiconductor devices using the nitride film of this example include photoelectric conversion devices, light emitting devices, MIS-FETs (field effect semiconductor devices), SL devices (super latex devices), and HEMT devices. Furthermore, the nitride film of this example can also be used for other semiconductor lasers or optical integrated circuits.

In this example, substrates that can be used to form the nitride film include silicon semiconductors, glass substrates, stainless steel substrates, metal tools, and the like. Substrates that can be used to form nitride films also include -compounds such as GaAs, GaAlAs,
There are InP, GaN, etc.

Furthermore, in FIG. 1, the substrate is placed on the lower side,
It is also possible to emit gas or electrons activated by the cyclotron resonance space 2 from above to below, or to apply an electric field from above to below.

〔Effect of the invention〕

According to the present invention, the inert gas and/or non-product gas activated by the cyclotron resonance space are mixed with the product gas to become a reactive gas, and further subjected to interaction due to the application of an electric field. A nitride film is formed on the substrate surface.

Since the exhaust system used a turbo pump in combination with a vacuum pump, it was possible to reduce the amount of undesirable oxygen and carbon when forming a nitride film.

Therefore, since unnecessary oxygen or carbon can be removed when forming a nitride film on the surface of the substrate, a high quality nitride film was formed.

According to the invention, the cyclotron resonance space is
Since it protrudes from the reaction chamber so as to be long in the direction perpendicular to the surface of the substrate on which the film is formed, which is held in the reaction chamber, it can be made narrower. Therefore, the air-core coil wound around the cyclotron resonance space can be made smaller, and an inexpensive method for forming a nitride film can be provided.

[Brief explanation of drawings]

FIG. 1 shows an outline of an interaction type plasma CVD apparatus using cyclotron resonance and an electric field according to the present invention. 1... Reaction chamber, 2... Cyclotron resonance space, 3... Microwave oscillator, 4... Analyzer, 5, 5'... Air core coil, 7... Halogen lamp heater, 8... Exhaust port, 10... board, 11
... Exhaust system, 12 ... Main body, 13, 13' ... Doping system, 16, 18 ... Introductory pipe, 17 ... Nozzle, 19 ... Quartz window, 20, 20' ... Electrode,
29...Quartz tube.

Claims (1)

[Claims] 1. A reaction chamber for forming a nitride film on the surface of a substrate;
A cyclotron resonance space is provided that protrudes from the reaction chamber so that the vertical direction is long with respect to the surface of the substrate, and the nitriding process is performed by simultaneously using energy obtained by cyclotron resonance and an electric field in the reaction chamber. A method for forming a nitride film on the surface of a substrate, wherein the inert gas and/or non-product gas activated by the cyclotron resonance space are:
The activated inert gas and/or non-product gas is supplied from the direction perpendicular to the film formation region, and the activated inert gas and/or non-product gas is mixed with the product gas supplied from the direction perpendicular to the film formation region in the reaction chamber. An electric field was applied perpendicularly to the reactive gas and the substrate, and the atmosphere in the reaction chamber was adjusted to 0.03 by using a turbo pump.
A method for forming a nitride film, characterized by forming a film on the surface of a substrate while maintaining the pressure in the range of ~0.001 torr. 2. A method for forming a nitride film according to claim 1, characterized in that the gas to be activated is selected from at least one of an inert gas, nitrogen, and a non-product gas consisting of a nitrogen compound gas. . 3. Claim 1 is characterized in that the product gas is selected from at least one of silane, disilane, silicon fluoride, a titanium compound, an aluminum compound, and a mixture of said compound and ammonia. A method for forming a nitride film.