JPH05251354A - Thin-film formation raw material used for chemical vapor growth as well as method and apparatus for chemical vapor growth used to form thin film on substrate by using said raw material - Google Patents

Abstract

PURPOSE:To form a thin film having a good film thickness and a good film quality by a CVD method wherein the flow rate of specific gasified silane is controlled, the silane is supplied into a reaction container in which a substrate has been arranged and the silane is decomposed and reacted on the substrate. CONSTITUTION:A substrate 4 is arranged on electrodes 2a, 2b which have been installed in parallel inside a reaction container 1; the reaction container 1 is evacuated to produce a vacuum. The substrate 4 is heated and its temperature is maintained. On the other hand, a storage container 7 which stores tridimethylaminesilicon as one of a chemical formula HxSi(NR2)4-x is heated. The tridimethylaminesilicon is introduced into the reaction container 1 while its flow rate is being controlled. On the other hand, ammonia gas which is stored in a storage container 8 and which has been gasified naturally is introduced into the reaction container 1 while its flow rate is being controlled. When a reaction condition has been stabilized, a voltage is applied across the electrodes 2a, 2b. Thereby, the gases existing between the electrodes are changed to a plasma, a methyl group is separated, and a silicon nitride film is formed on the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming raw material used when a thin film is formed on a substrate by chemical vapor deposition, and a method and apparatus for forming a thin film by chemical vapor deposition using this raw material. ..

[0002]

2. Description of the Related Art The chemical vapor deposition (CVD) method is a method of forming a thin film on a substrate by introducing a source gas onto a substrate and causing a chemical reaction such as thermal decomposition reduction. This CVD method is used for forming a film of an insulating material such as a food material, an abrasion resistant material, a hardening material, etc. on the surface of a semiconductor wafer or the like.

When forming a thin film of silicon or a silicon compound by the CVD method, monosilane (SiH ₄ ),
Disilane (SiH ₄ ) or the like is used as the raw material. FIG. 2 is a schematic view of a conventional plasma CVD apparatus that uses these raw materials to form a thin film of silicon or a silicon compound by the CVD method.

In FIG. 2, two sets of electrodes 2 are arranged in a reaction vessel 1 in a staggered and parallel manner.
a and 2b are arranged, and a heating means 3 composed of a coil is arranged so as to surround the periphery of the reaction vessel 1. Substrates 4 are arranged on both sides of the electrodes 2a and 2b (however, inside the electrodes on both ends). Plasma can be generated between the electrodes by the high frequency power supply 2c connected to the electrodes.

Upstream of the reaction vessel 1, storage vessels 7a, 7b and 7c for storing film forming raw materials are connected via a valve 5 and a flow rate controller 6. Each storage container stores, for example, SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl _{2, and the} like. Similarly, the reaction container 1 is provided with storage containers 8a to 8e for storing a carrier gas necessary for forming a predetermined thin film by reacting with a raw material for forming a thin film via a valve 5'and a flow rate controller 6 '. It is connected. NH ₃ , N ₂ O, N ₂ , O ₂ , CH _4, etc. are stored in each storage container.

A vacuum device 9 for evacuating the reaction container is connected downstream of the reaction container 1, and a pressure control device 10 for controlling the pressure inside the reaction container is provided between the reaction container 1 and the vacuum device 9. It is installed in between.

[0007]

The silicon compound as a raw material used in such an apparatus has high flammability,
It is generally known that it is extremely dangerous, its handling is difficult, and that even if it is released into the air due to a leak or the like, it will explosively burn, leading to an explosion accident or a fire accident. Therefore, in order to prevent such an accident, a leak prevention device, a safety device, etc. are provided, but this complicates the entire device, raises the manufacturing cost, and further increases the running cost. Furthermore, in addition to the operation for forming a thin film, a periodical inspection for safety management is required, so that the operability of the device must be lowered.

By the way, the conventional reaction between the raw material for the thin film and the carrier gas follows the reaction steps of decomposition, bonding and film formation reaction. For example, when the raw material is SiH ₄ and the carrier gas is NH ₃ , a decomposition reaction such as decomposition of silicon and hydrogen, decomposition of nitrogen and hydrogen occurs first, and then a bond reaction between silicon and nitrogen occurs, and finally, Si A nitride film of ₃ N ₄ is formed on the substrate. It is very difficult to control such a complicated reaction, and thus it has been very difficult to control the film thickness and the film quality. In addition, the step coverage with respect to the base was also poor.

Therefore, an object of the present invention is to provide a raw material for film formation, which is safe and easy to control the film formation reaction when various silicon films and the like are formed on a substrate by the CVD method.

Another object of the present invention is to obtain a good film thickness and film quality by the CVD method by using a film forming raw material which is safe and can easily control the film forming reaction when forming a silicon film or the like on a substrate. It is to provide a method of forming a thin film.

Further, an object of the present invention is to use a raw material for film formation, which is safe and easy to control a thin film formation reaction when forming a silicon film on a substrate, and to obtain a thin film having a good film thickness and film quality by a CVD method. Is to provide a device for forming.

[0012]

The raw material for film formation used in the chemical vapor deposition of the present invention is represented by the chemical formula HxSi (N
R ₂ ) _4-x . Here, R is an alkyl group, and x =
It is 0, 1, 2, 3.

The method of forming a film on the substrate by chemical vapor deposition is as follows: a) preparing a film forming raw material represented by the chemical formula H _x Si (NR ₂ ) _4-x ; A step of gasifying, c) a step of controlling the flow rate of the gasified raw material to supply it into the reaction vessel in which the substrate is arranged, d) a step of decomposing the supplied gas on the substrate, and e) The process of maintaining the decomposition reaction of gas until a desired film thickness is formed.

Here, the pressure of the supplied source gas may be normal pressure or a low pressure of 0.5 to 50 Torr.

The method of forming a film on a substrate by chemical vapor deposition according to the present invention further controls the flow rate of the separation gas,
It may include a step of mixing the supplied raw material gas in the reaction vessel.

When the film to be formed on the substrate is a silicon nitride film, the separation gas is hydrogen, nitrogen or ammonia gas, and when the film to be formed on the substrate is a silicon oxide film, the separation gas is oxygen gas. , Ozone or nitrous oxide, and the film to be formed on the substrate is a silicon oxynitride film, the separation gas is oxygen gas and ammonia gas or nitrous oxide, and the film to be formed on the substrate is silicon. When it is a carbonized film, the separation gas is carbon tetrachloride gas.

The apparatus of the present invention for depositing a film on a substrate by chemical vapor deposition includes a) a reaction vessel in which the substrate is placed in a vacuum chamber and the substrate is placed inside the vessel, and b) a flow controller in the vessel. A storage container connected to store a raw material for forming a film having a chemical formula of H _x Si (NR ₂ ) _4-x , and c).
A means for decomposing the raw material introduced into the reaction vessel on the substrate, and a discharge means for discharging waste gas in the reaction vessel,
It consists of

The apparatus for forming a film on a substrate by chemical vapor deposition according to the present invention may further include a storage container for storing a separation gas, which is connected to the reaction container via a flow controller.

[0019]

The raw material for film formation represented by the chemical formula HxSi (NR ₂ ) _4-x of the present invention is safe because it does not react with air at all.

Since the raw material for forming the film of the present invention has a Si--N bond in it, unnecessary elements are separated from the raw material gas by using an appropriate separation gas, and the raw material gas is deposited on the substrate. A desired thin film is formed. For example, when forming a silicon nitride film (Si ₃ N ₄ ) and using hydrogen or ammonia as a separation gas, methyl groups are separated from the source gas and a film formation reaction occurs to form a silicon nitride film on the substrate. It

[0021]

EXAMPLE FIG. 1 shows an apparatus for forming a thin film on a substrate by a plasma CVD method using a film forming raw material represented by the chemical formula HxSi (NR ₂ ) _4-x of the present invention. 1, the same elements as those of the apparatus shown in FIG. 2 are designated by the same reference numerals.

In the apparatus shown in FIG. 1, two sets of electrodes 2a and 2b, which are arranged alternately and in parallel, are arranged in a reaction vessel 1, and a coil is arranged so as to surround the circumference of the reaction vessel 1. A heating means 3 consisting of Substrates 4 are arranged on both sides of the electrodes 2a and 2b (however, inside the electrodes on both ends). Plasma can be generated between the electrodes by the high frequency power supply 2c connected to the electrodes.

A storage container 7 for storing a film-forming raw material is connected upstream of the reaction container 1 via a valve 5 and a flow rate controller 6. Since the raw material for forming the film of the present invention is liquid at room temperature, the heater 7a is used to gasify the raw material.
Is provided.

A storage container 8 is connected to the reaction container 1 via a valve 5'and a flow rate controller 6'to store a separation gas for forming a predetermined thin film by separating and reacting with a raw material for film formation.

A vacuum device 9 for evacuating the reaction container is connected downstream of the reaction container 1, and a pressure control device 10 for controlling the pressure inside the reaction container is provided between the reaction container 1 and the vacuum device 9. It is installed in between.

The above-mentioned apparatus is a suitable apparatus, but in addition to this, a plasma CVD apparatus or a thermal CVD apparatus for carrying out a reaction under normal pressure, that is, a substrate is heated to a high temperature to form a film on its surface by a chemical reaction. Equipment (Low pressure CVD method, Normal pressure CV
(Including the case of method D) may also be used.

A silicon nitride film (Si _{3) is formed} on a substrate using tridimethylamine silicon (hereinafter referred to as TDMAS), which is one of the chemical formulas HxSi (NR ₂ ) _4-x , as a raw material and ammonia as a separation gas. The operation of forming N ₄ ) will be described below.

A plurality of substrates 4 are arranged on the electrodes 2a and 2b arranged in parallel in the reaction container 1 so as to face each other, and the reaction container 1 is evacuated by a vacuum device. Then, the temperature of the substrate 4 is set to 100 to 400 ° C. by the heating means 3.
And keep heating.

On the other hand, the storage container 7 for storing TDMAS is heated to 50 ° C. to 100 ° C. by the heater 7a. This is because TDMAS as a raw material is a liquid at room temperature. As a result, TDMAS is gasified. The generated source gas is 100 to 500c by the flow rate controller 6.
It is introduced into the reaction vessel 1 via the valve 5 while controlling the flow rate at c / min. Here, as a preferred example, the raw material is TD
Although MAS was used, monodimethylamine silicon, didimethylamine silicon, etc., which are other examples of the chemical formula H _x Si (NR ₂ ) _4-x , can also obtain good film thickness and film quality as in TDMAS.

On the other hand, the separated gas is stored in the storage container 8,
The naturally vaporized ammonia gas is introduced into the reaction vessel 1 through the valve 5'while controlling the flow rate to 1 to 10 liters / min by the flow rate controller 6 '.

Each of the introduced gases is already in the vacuum device 9
Are mixed in the reaction container 1 that has been evacuated. The pressure is adjusted by the pressure control device so that the pressure in the reaction vessel 1 becomes 0.5 to 50 Torr.

When the reaction conditions are stable, the high frequency power source 2
A voltage is applied to the electrodes 2a and 2b by c. This allows
The gas between the electrodes is turned into plasma, the separation reaction of the source gas by the separation gas, that is, the methyl group is separated, and a silicon nitride film is formed on the substrate. Thus, TDMA
By using S, a film formation reaction occurs at the same time that a decomposition reaction occurs, and thus the reaction process is simplified. This is in contrast to the use of conventional raw materials, which had to undergo a decomposition reaction, a binding reaction, and a film formation reaction to form a film.

By-products and unreacted gas generated during film formation are exhausted to an exhaust gas treatment system (not shown) by the vacuum exhaust device 9.

Although ammonia gas was used as the separation gas, hydrogen or ammonia gas is used when the film to be formed on the substrate is a silicon nitride film, and hydrogen gas or ammonia gas is used when the film to be formed on the substrate is a silicon oxide film. Oxygen gas, oxygen gas or ammonia gas is used when the film to be formed on the substrate is a silicon oxynitride film, and carbon tetrachloride gas is used when the film to be formed on the substrate is a silicon carbide film.

FIG. 3 is a graph of Fourier transform infrared absorption spectroscopy analysis of the film formed by the above process. As shown in FIG. 3, it was confirmed that the film had a sharp peak in Si—N, and thus the film was a nitride film.

FIG. 4 shows the relationship between the deposition rate of the thin film and the output of the high frequency power source in the thin film forming step according to the present invention. As can be seen from this figure, the relationship between the deposition rate and the output of the high-frequency power source is simple. Therefore, by controlling the deposition rate and the film formation (deposition) time, an arbitrary film thickness can be formed.

The following table shows the compressive stress and the refractive index of the nitride film formed by using the TDMAS of the present invention and the nitride film formed by using the conventional raw material. Table Raw material Compressive stress (× 10 ⁹ (dyn / cm ² ) Refractive index TDMAS + NH ₃ 0.8 to 1.2 1.95 SiH ₄ + NH _{3 3 to} 5 2.05 As is clear from this table, When the film is formed, the compressive stress is smaller than that of the prior art, so that when aluminum is wired on a substrate, for example, when a silicon nitride film is formed on the aluminum, the load on the aluminum is significantly reduced as compared with the prior art. And a good film can be formed.

FIG. 5 shows a cross section of a thin film formed on a substrate having a step using a raw material for forming a TDMA film and a thin film formed on a substrate using a conventional raw material. As is clear from this figure, the step coverage of the underlayer of the thin film formed according to the present invention is superior to the conventional one.

[0039]

As described above, the use of the film forming raw material of the present invention eliminates the risk of explosion, fire, etc., simplifies the apparatus, simplifies the operation of the apparatus, and Manufacturing costs are reduced. Furthermore,
According to the present invention, a good film quality can be formed and the film thickness can be easily controlled.

[Brief description of drawings]

FIG. 1 is a plasma CV using the film forming raw material of the present invention.
An apparatus for forming a thin film on a substrate by the D method is shown.

FIG. 2: Plasma CVD using conventional film forming raw materials.
An apparatus for forming a thin film on a substrate by the method is shown.

FIG. 3 is a spectrum graph showing that a thin film formed on a substrate using a TDMA film forming raw material is a nitride film.

FIG. 4 shows a relationship between a deposition rate of a thin film and a high frequency power output in a thin film forming process according to the present invention.

FIG. 5 shows cross sections of a thin film formed on a substrate using a TDMA film forming raw material and a thin film formed on a substrate using a conventional raw material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2a, b Electrode 2c High frequency power supply 3 Heating means 4 Substrate 5, 5'valve 6, 6'Flow controller 7 Raw material storage container 7a Heater 8 Separation gas storage container 9 Vacuum device 10 Pressure control device

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[Procedure amendment]

[Submission date] June 14, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yozo Ikedo 2-23-3 303 Higashi Hashimoto, Sagamihara City, Kanagawa Prefecture (72) Hideaki Machida 2-5275-1 105 Komatsubara, Zama City, Kanagawa Prefecture

Claims (17)

[Claims] 1. A method for forming a film on a substrate by chemical vapor deposition, comprising: a) a chemical formula H _x Si (NR ₂ ) _4-x , wherein R is an alkyl group, and x = 0, A step of preparing a film-forming raw material which is 1, 2, or 3; b) a step of gasifying the raw material; and c) controlling the flow rate of the gasified raw material into the reaction vessel in which the substrate is placed. A method comprising: a supplying step, d) a decomposition reaction of the supplied gas on the substrate, and an e) maintaining the decomposition reaction of the gas until a desired film thickness is formed. 2. The method according to claim 1, wherein the pressure of the supplied gas is normal pressure. 3. The method according to claim 1, wherein the pressure of the supplied gas is 0.5 to 50 Torr. 4. The method according to claim 2 or 3, wherein the decomposition reaction step is a step of generating plasma to cause a decomposition reaction. 5. The method according to claim 2 or 3, wherein the decomposition reaction step is a step of causing the decomposition reaction by heating the substrate. 6. The method according to claim 1, further comprising the step of controlling the flow rate of the separated gas and mixing the supplied gas with the supplied gas in the reaction vessel. 7. The method according to claim 6, wherein the decomposition reaction step is a step of heating the substrate and then supplying a raw material and a separation gas into the reaction vessel to generate plasma to cause a separation reaction. That's the way. 8. The method according to claim 7, wherein when the film to be formed on the substrate is a silicon nitride film, the separation gas is hydrogen, nitrogen or ammonia gas.
By the way. 9. The method according to claim 7, wherein when the film to be formed on the substrate is a silicon oxide film, the separation gas is oxygen gas, ozone or dinitrogen monoxide. .. 10. The method according to claim 7, wherein when the film to be formed on the substrate is a silicon oxynitride film, the separation gas is oxygen gas and ammonia gas, or dinitrogen monoxide. By the way. 11. The method according to claim 7, wherein when the film to be formed on the substrate is a silicon carbide film, the separated carbon tetrachloride gas is used. 12. An apparatus for forming a film on a substrate by chemical vapor deposition, comprising: a) a reaction vessel which is evacuated by a vacuum apparatus and in which the substrate is placed; and b) a flow controller in the vessel. A storage container for storing a film-forming raw material, wherein R is an alkyl group and x = 0, 1, 2, 3 and is represented by the chemical formula H _x Si (NR ₂ ) _4-x , ) An apparatus comprising: a means for separating and reacting the raw material flowing into the reaction container on the substrate; and d) a discharging means for discharging a waste gas in the reaction container. 13. The apparatus according to claim 12, further comprising a storage container for storing separated gas, which is connected to the reaction container via a flow controller. 14. The apparatus of claim 12, further comprising means for gasifying the feedstock. 15. The apparatus according to claim 12, wherein the separation reaction means comprises an electrode on which the substrate is arranged, and a high frequency power source connected to the electrode. 16. A chemical formula HxSi (NR ₂ ) _4-x , which is supplied in the gas state in the vicinity of a substrate on which a film is formed and is used in chemical vapor deposition for forming a film on the substrate by a chemical reaction, A raw material for film formation, wherein R is an alkyl group and x = 0, 1, 2, 3. 17. A chemical formula of H _x Si (NR ₂ ) _4-x ,
When R is an alkyl group and x = 0,1,2,3, the film-forming raw material is gasified and mixed with a separation gas, and the gas is caused to flow in the vicinity of the heated substrate, and then the raw material is formed on the substrate. A substrate having a nitride film formed on the substrate by decomposing a gas.