JP2012142586A - Film forming material and film forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique which is capable of providing an Si-based film with safety, at a relatively low temperature, and at a low cost, without using SiHhaving a high risk of explosion.SOLUTION: A film forming material for forming the Si-based film contains t-CHSiX(X is an arbitrary group) and a reactive compound which reacts with the t-CHSiX.

Description

  The present invention relates to the technology of Si-based films. In particular, the present invention relates to a material for forming a Si-based film and a film forming method.

Many elements in various fields such as semiconductor elements, silicon-based solar cells, and biological devices are provided with Si-based films. Silane (SiH ₄ ) is used to form this type of Si-based film. However, should there be disassembled SiH ₄ for the formation of Si-based film using SiH _4. This decomposition of SiH ₄ requires a high temperature of 700 ° C. or higher. However, when the substrate on which the film is formed is a resin, or when a component such as an integrated circuit that is likely to cause thermal damage is provided, a Si system using SiH ₄ that requires a high temperature of 700 ° C. or higher. Formation of the film is extremely difficult. That is, the use of SiH ₄ is not preferable because thermal damage is caused to the substrate and the electronic circuit.

It is conceivable that SiH ₄ is plasma-decomposed. That is, according to plasma decomposition, SiH ₄ can be decomposed without being maintained at a high temperature of 700 ° C. or higher, and a Si-based film can be formed. However, when the plasma decomposition method is used, the substrate is exposed to plasma, and the substrate is damaged. Furthermore, when plasma is used, the usage efficiency of SiH ₄ is as low as about 10% and the cost is high.

Furthermore, SiH ₄ has a high risk of explosion. There have been explosions in the past. For this reason, a safety device is required for the film forming apparatus, which is expensive.

As research for solving the above-mentioned problems has been intensively pursued, the present inventor has found that a compound in which one of four H atoms in SiH ₄ is substituted with an alkyl group is ignited in air. It came to find that the nature and explosiveness decline. And, when various alkyl groups were examined, when the alkyl group was a tertiary butyl group (t-C ₄ H ₉ ), this compound was found to have a relatively low decomposition temperature. That is, it has been found that it is suitable for film formation by CVD. For example, when forming a Si-based film by CVD (chemical vapor deposition method), the use of _t-C 4 H 9 SiX ₃ in place of SiH _4, problems due to SiH ₄ was significantly improved .

However, as the film forming material, t-C ₄ even when only only H ₉ SiX ₃ was used, it was found that that has a problem in carbon impurity quantity of example film.

Therefore, the problem to be solved by the present invention is to improve the above problems. For example, the first problem to be solved by the present invention is to provide a technology capable of providing a Si-based film at a low cost without using SiH ₄ which has a high risk of explosion.

  The second problem to be solved by the present invention is to provide a technique capable of forming a Si-based film safely.

  A third problem to be solved by the present invention is to provide a technique capable of forming a Si-based film at a temperature of 400 ° C. or lower.

  The fourth problem to be solved by the present invention is to provide a technique capable of forming a high purity (high quality) Si-based film.

While research for solving the above-mentioned problems has been eagerly pushed forward, the present inventor can greatly improve the above problems when t-C ₄ H ₉ SiX ₃ and azide are used in combination. I came to find. For _{example, CH 3 N 3, C 2} H 5 N 3, n-C 3 H 7 N 3, i-C 3 H 7 N 3, n-C 4 H 9 N 3, sec-C 4 H 9 N 3, _{t-C 4 H 9 N 3} , if the azide said alkyl azide such as _{C 6} H 5 _{N 3} is used in combination, (1) a carbon impurity is reduced in the film, (2) film forming rate The fast (3) t-C ₄ H ₉ SiX ₃ usage rate was high. In particular, when the obtained film is a SiN film, the above-mentioned feature is remarkable. In addition, when the reactive compound such as H ₂ , NH ₃ , CH ₃ NHNH ₂ , (CH ₃ ) ₂ NNH ₂ is used in combination instead of the azide, the above problems are improved. .

  The present invention has been achieved based on such findings.

That is, the above problem is
A film forming material for forming a Si-based film,
The film forming material is
_{t-C 4} H 9 _SiX 3 and (X is any group),
This is solved by a Si-based film forming material comprising a reactive compound that reacts with the t-C ₄ H ₉ SiX ₃ .

In particular, a film forming material for forming a Si-based film,
The film forming material is
_{t-C 4} H 9 _SiX 3 and (X is any group),
And a reactive compound reacting with the _{t-C 4 H 9 SiX 3} ,
The reactive compound is solved by an Si-based film forming material, wherein the reactive compound is at least one selected from the group of azides, amines, hydrazines, and H ₂ .

Furthermore, a film forming material for forming a Si-based film,
The film forming material is
t-C ₄ H ₉ SiX ₃ (X is any one selected from the group consisting of a hydrogen atom, a halogen atom, an alkoxy group, an alkylamino group, and N ₃ );
And a reactive compound reacting with the _{t-C 4 H 9 SiX 3} ,
The reactive compound is solved by an Si-based film forming material, wherein the reactive compound is at least one selected from the group of azides, amines, hydrazines, and H ₂ .

The Si-based film forming material according to the present invention is more preferably solved by the Si-based film forming material characterized in that the reactive compound is an azide. Further, the Si-based film forming material according to the present invention is more preferably solved by the Si-based film forming material characterized in that the reactive compound is an alkyl azide. Among them, in the Si-based film forming material according to the present invention, the reactive compounds are CH ₃ N ₃ , C ₂ H ₅ N ₃ , n-C ₃ H ₇ N ₃ , i-C ₃ H ₇ N ₃ , _{n-C 4 H 9 n 3} , sec-C 4 H 9 n 3, t-C 4 H 9 n 3, characterized in that one or more compounds selected from the group consisting of _{C 6} H 5 _{n 3} This is solved by the Si-based film forming material.

Also, a Si-based film forming method comprising forming the Si-based film by supplying the Si-based film forming material, that is, the t-C ₄ H ₉ SiX ₃ and the reactive compound onto a substrate. Solved by.

  In particular, the present invention is solved by a Si-based film forming method characterized in that a Si-based film is formed by supplying the Si-based film forming material onto a substrate in a gas phase.

  Further, the invention is solved by an element comprising a Si-based film formed by the film forming method.

  An Si-based film could be formed at low cost and safely and without damage to the substrate on which the film was formed. Moreover, there were few carbon impurities in the obtained film. An amorphous or polycrystalline Si-based film was obtained.

the vapor pressure curve of _{t-C 4} H 9 SiH ₃ Schematic diagram of film deposition equipment (CVD)

The first aspect of the present invention is a Si-based film forming material. The Si-based film is, for example, a silicon film or a silicon nitride film. Above all, it is an amorphous or polycrystalline Si-based film. The Si-based film is a Si-based film formed by CVD using a compound (Si-based film forming material) described later. The Si-based film forming material serving as the Si source in the Si-based film is t-C ₄ H ₉ SiX ₃ . X is an arbitrary group. All Xs may be the same or different. Preferred X is a halogen atom (for example, Cl), an alkoxy group (OR: R is an alkyl group. Preferred alkyl groups are those having 10 or less carbon atoms, such as OCH ₃ , OC ₂ H _5, etc.), alkyl The amino group (NR′R ″: R ′, R ″ is an alkyl group. Preferred alkyl groups have 10 or less carbon atoms. For example, N (CH ₃ ) ₂ , N (C ₂ H _{5 2} ) etc. N _{3 is} also a preferred X. H is also a preferred X. The t-C ₄ H ₉ SiX ₃ may contain some impurities. However, the purity is preferably 99% or more. Only one type of t-C ₄ H ₉ SiX ₃ may be used as the Si-based film forming material serving as the Si source. However, two or more compounds in which X is a different group may be used. Within a range that does not impair the features of the present invention _t-C 4 H 9 SiX ₃ other Si-based compound can be used.

The Si-based film forming material (Si-based compound) serving as the Si source is t-C ₄ H ₉ SiX ₃ . In the present invention, it is essential to use a reactive compound that reacts with tC ₄ H ₉ SiX ₃ in combination. This reactive compound is particularly preferably a reactive compound that reacts with t-C ₄ H ₉ SiX ₃ at a temperature of 100 ° C. or higher. The upper limit value of the temperature is not particularly limited. However, the temperature at the time of film formation performed by CVD becomes the upper limit. That is, if the temperature during film formation is 400 ° C., 400 ° C. is the upper limit. In the present invention, the temperature is preferably lower than the temperature (700 ° C.) when SiH ₄ is used. Therefore, a temperature of 600 ° C. or lower is preferable. Furthermore, the temperature of 500 degrees C or less is preferable. More preferably, it is 400 degrees C or less. Among the reactive compounds, azide is preferable. Among these, alkyl azides having 10 or less carbon atoms are preferred. For example, _{CH 3 N} 3 (azide _{methyl), C 2 H 5 N 3} ( azide _{ethyl), n-C 3 H 7} N 3 ( azide normal _{propyl), i-C 3 H 7} N 3 ( azide _{isopropyl), n-C 4 H 9} n 3 ( azide normal _{butyl), sec-C 4 H 9} n 3 ( azide secondary _{butyl), t-C 4 H 9} n 3 ( azide tertiary butyl), C ₆ H ₅ N ₃ (phenyl azide) and the like are the most preferred azides. Preferred reactive compounds used in addition to the azide include amines (amines such as NH ₃ ), hydrazines (hydrazines (alkyl hydrazines) such as CH ₃ NHNH ₂ and (CH ₃ ) ₂ NNH ₂ ), and it is H _2.

The second aspect of the present invention is a Si-based film forming method. That is, it is a method for forming a Si-based film by supplying the film forming material (compound) onto a substrate. In particular, a method of forming a Si-based film by supplying the _t-C 4 H 9 SiX _3, and the reactive compound reacted with the _t-C 4 H 9 SiX ₃ on the substrate. Furthermore, it is a method of forming a Si-based film by supplying the film forming material (compound) onto the substrate in a gas phase state. If only _{t-C 4} H 9 SiX ₃ supplied onto the _substrate, it is _t-C 4 H 9 SiX ₃ may only be transported from one container being filled. Of course, when two or more kinds of t-C ₄ H ₉ SiX ₃ are supplied, they may be transported from the corresponding number of containers, or may be transported from one mixed container. . In the case of forming a film using the tC ₄ H ₉ SiX ₃ and the reactive compound, each material (compound) is basically filled in a separate container. Therefore, basically, the transport route is different until reaching the film forming chamber. Of course, the final route in the transport route to the film forming chamber may be common. The reactivity with the t-C ₄ H ₉ SiX ₃ and the reactive compound, because I and preferably one which reacts at 100 ° C. or higher, the temperature is lower than 100 ° C. in the normal transportation routes In consideration, since the reaction in the transport route under a temperature lower than 100 ° C. cannot be considered, the transport route may be shared, and both may be mixed in the same container. However, it is still preferable that they are filled in separate containers and transported by separate routes to the film formation chamber. When the t-C ₄ H ₉ SiX ₃ or the reactive compound is transported to the film formation chamber and formed into a film, the compound follows a decomposition step. This decomposition step employs, for example, a thermal decomposition, a photodecomposition, and / or a hot filament decomposition method. In the hot filament decomposition, the filament is disposed in front of the film formation location (deposition location), and the vapor phase raw material is decomposed by the heated filament.

  The third aspect of the present invention is an element. For example, an element such as a semiconductor element having a Si-based film, a silicon-based solar cell, or a biological device. This element includes a Si-based film formed by the above film forming method. Alternatively, a Si-based film formed by CVD using the Si-based film forming material is provided.

More specific description will be given below. In addition, this invention is not limited only to a following example. For example, a reactive compound (gas phase reactive compound) used in combination with t-C ₄ H ₉ SiX ₃ includes azides such as CH ₃ N ₃ and C ₂ H ₅ N _3, but other than this Similar results were obtained using the azide.

[Reference Examples 1 to 7]
Synthesis of t-C ₄ H ₉ SiH ₃ in which X is H in t-C ₄ H ₉ SiX ₃ was performed.
Synthesis of t-C ₄ H ₉ SiCl ₃ in which X in t-C ₄ H ₉ SiX ₃ is a halogen atom was performed.
_{t-C 4} H 9 SiX (the R carbon atoms of 10 or less alkyl group) X is OR in ₃ is _{t-C 4 H 9 Si (} OCH 3) 3, t-C 4 H 9 Si (OC 2 H ₅ ) Synthesis of ₃ was performed.
_{t-C 4 H 9 SiX 3} X is in NR'R '' (R ', R '' is the number of carbon atoms of 10 or less alkyl group) _{t-C 4 H 9 Si (} N (CH 3) 2) _{3, t-C 4 H 9} Si (N (C 2 H 5) 2) 3 synthesis was performed.
Synthesis of t-C ₄ H ₉ Si (N ₃ ) ₃ in which X in t-C ₄ H ₉ SiX ₃ is N ₃ was performed.
The above compounds were not ignitable or explosive in the air. That is, the handling ability was far better than SiH ₄ .
Moreover, as can be seen from the vapor pressure curve of t-C ₄ H ₉ SiH ₃ shown in FIG. 1, it had a sufficient vapor pressure during CVD. _{t-C 4 H 9 SiCl 3} , t-C 4 H 9 Si (OCH 3) 3, t-C 4 H 9 Si (OC 2 H 5) 3, t-C 4 H 9 Si (N (CH 3) _{2) 3, t-C 4} H 9 Si (N (C 2 H 5) 2) 3, t-C 4 H 9 Si (N 3) 3 also, during CVD, had a sufficient vapor pressure .
And by performing CVD using the said compound, the Si-type film | membrane was able to be easily formed on the board | substrate.
The film obtained in Reference Example 1 in which t-C ₄ H ₉ SiH ₃ was used was a Si film.
The film obtained in Reference Example 2 in which t-C ₄ H ₉ SiCl ₃ was used was a Si film.
The film obtained in Reference Example 3 in which t-C ₄ H ₉ Si (OCH ₃ ) ₃ was used was a SiOC film.
the film obtained in _{t-C 4 H 9 Si (} OC 2 H 5) Reference Example _{4 3} was used was SiOC film.
_{t-C 4 H 9 Si (} N (CH 3) 2) 3 was obtained in Reference Example 5 was used film was SiCN film.
_{t-C 4 H 9 Si (} N (C 2 H 5) 2) 3 was obtained in Reference Example 6 was used film was SiCN film.
The film obtained in Reference Example 7 in which t-C ₄ H ₉ Si (N ₃ ) ₃ was used was a SiN film.

[Example 1]
The above reference example film forming material was only _{t-C 4 H 9 SiX 3} . However, in this example, a reactive compound was used in addition to t-C ₄ H ₉ SiX ₃ . FIG. 2 is a schematic diagram of a film formation apparatus (CVD apparatus) used for film formation in this example. In FIG. 2, 1 is a container filled with a raw material (t-C ₄ H ₉ SiX ₃ ), 2 is a heater, 3 is a decomposition reactor, 4 is a substrate, 5 is a flow controller, and 6 is a flow of raw material gas. Outlet, 7 is an introduction line for a reactive compound (reactive compound that reacts with tC ₄ H ₉ SiX ₃ ), 8 is a carrier gas introduction line, 9 is an exhaust system, 10 is a ring-shaped hot filament, 11 is The light irradiator 12 is a pressure adjusting needle valve in the raw material container.
In the container 1 maintained at −20 ° C. to 0 ° C., t-C ₄ H ₉ SiH ₃ is placed. The decomposition reactor 3 is evacuated to a vacuum. The Si substrate 4 is heated to 300 to 400 ° C. Then, the needle valve 12 was opened, and the vaporized t-C ₄ H ₉ SiH ₃ was introduced into the decomposition reaction furnace 3 through a pipe. When t-C ₄ H ₉ SiH ₃ was introduced into the decomposition reaction furnace 3, a reactive gas (reactive compound: H ₂ ) was introduced at a rate of 20 ml / min through the introduction line 7.
A film was formed on the substrate 4 by the CVD. As a result of examining the formed film by XPS (X-ray photoelectron analysis) and X-ray, it was confirmed that an amorphous Si film was formed on the substrate. It was confirmed that a polycrystalline Si film was formed under conditions where the substrate temperature was close to 400 ° C.
Similar results were obtained when a glass substrate, an aluminum foil substrate, or a resin substrate was used instead of the Si substrate.
In Example 1 where t-C ₄ H ₉ SiX ₃ and a reactive compound were used in combination, carbon impurities in the film were compared to Reference Example 1 where no reactive compound (H ₂ ) was used. The amount of the Si film having a higher purity could be formed.

[Example 2]
In the same manner as in Example 1 except that t-C ₄ H ₉ SiCl ₃ was used instead of t-C ₄ H ₉ SiH ₃ , an amorphous Si film was formed on the substrate 4.
In Example 2 in which t-C ₄ H ₉ SiX ₃ and a reactive compound were used in combination, the carbon in the film and the amount of carbon in the film were compared to Reference Example 2 in which the reactive compound (H ₂ ) was not used. The amount of chlorine impurities was small, and a higher purity Si film could be formed.

[Examples 3a and 3b]
In Examples 1 and 2, the filament 10 was energized, the filament 10 was heated to 1600 ° C., the substrate was held at 200 ° C., and film formation by hot filament CVD was performed.
As a result of examining the film obtained by this film formation by XPS and X-rays, it was confirmed that the film was an amorphous SiC film.
As a result of conducting the filament 10 at 1000 ° C. in the same manner, it was confirmed that the film was a polycrystalline Si film.

[Examples 4a and 4b]
In Examples 1 and 2, the substrate was held at 200 ° C. while applying light to the substrate with the light irradiator 11, and film formation by CVD was performed.
As a result of examining the film obtained by this film formation by XPS and X-rays, it was confirmed that the film was an amorphous Si film.

[Examples 5a and 5b]
In Examples 1 and 2, was carried out as but using _CH 3 _{N 3} as the reactive gas instead of _{H 2.} As a result, it was confirmed that the film formed on the substrate 4 was an amorphous SiN film.
When comparing the film obtained in this example using azide as the reactive gas and the film obtained in Examples 1 and 2 using H ₂ as the reactive gas, the film obtained in this example is The film forming speed was high, the usage rate of t-C ₄ H ₉ SiH ₃ was high, and the carbon impurity amount in the film was low.

[Examples 6a and 6b]
In Examples 1 and 2, was carried out as except for using _C 2 _H 5 _{N 3} as the reactive gas instead of _{H 2.} As a result, it was confirmed that the film formed on the substrate 4 was an amorphous SiN film.
When comparing the film obtained in this example using azide as the reactive gas and the film obtained in Examples 1 and 2 using H ₂ as the reactive gas, the film obtained in this example is The film forming speed was high, the usage rate of t-C ₄ H ₉ SiH ₃ was high, and the carbon impurity amount in the film was low.

[Examples 7a and 7b]
In Examples 1 and 2, was carried out as but using _CH 3 NHNH ₂ as a reactive gas instead of _{H 2.} As a result, it was confirmed that the film formed on the substrate 4 was an amorphous SiN film.
When comparing the film obtained in this example using hydrazine as the reactive gas and the film obtained in Examples 1 and 2 using H ₂ as the reactive gas, the film obtained in this example was The film forming speed was fast, the usage rate of t-C ₄ H ₉ SiH ₃ was high, and the carbon impurity amount in the film was low.
The membrane is better

[Examples 8a and 8b]
In Examples 1 and 2, was carried out as except for the use as a reactive gas in place of _{H 2} and _{(CH 3) 2} NNH 2. As a result, it was confirmed that the film formed on the substrate 4 was an amorphous SiN film.
When comparing the film obtained in this example using hydrazine as the reactive gas and the film obtained in Examples 1 and 2 using H ₂ as the reactive gas, the film obtained in this example was The film forming speed was fast, the usage rate of t-C ₄ H ₉ SiH ₃ was high, and the carbon impurity amount in the film was low.

[Example 9]
In Example 1, it was carried out as but using NH ₃ as the reactive gas instead of H _2. As a result, it was confirmed that the film formed on the substrate 4 was an amorphous SiN film.
When the film obtained in this example using amines (ammonia) as the reactive gas was compared with the film obtained in Example 1 using H ₂ as the reactive gas, the film obtained in this example. The amount of carbon impurities in the film was low.

[Example 10]
Except for using _{t-C 4 H 9 Si (} N 3) 3 in place of _t-C 4 H 9 SiH ₃ used in Example 1 were carried out in the same manner. As a result, it was confirmed that the film formed on the substrate 4 was an amorphous SiN film.

[Example 11]
T-C ₄ H ₉ Si (OC ₂ H ₅ ) ₃ was used in place of t-C ₄ H ₉ SiH ₃ used in Example 1, and NH ₃ was used in place of H ₂ as a reactive gas. Did the same. As a result, it was confirmed that the film formed on the substrate 4 was an amorphous SiN film.

[Example 12]
T-C ₄ H ₉ Si (N (CH ₃ ) ₂ ) ₃ was used instead of t-C ₄ H ₉ SiH ₃ used in Example 1, and NH ₃ was used instead of H ₂ as a reactive gas. I went in the same way except. As a result, it was confirmed that the film formed on the substrate 4 was an amorphous SiN film.

[Example 13]
Alternatively _t-C 4 H 9 _Si of _t-C 4 H 9 SiH ₃ used in Example _{1 (N (C 2 H 5} ) 2) 3 NH 3 instead of _{H 2} as a reactive gas together with The procedure was the same except that was used. As a result, it was confirmed that the film formed on the substrate 4 was an amorphous SiN film.

DESCRIPTION OF SYMBOLS 1 Container 2 Heater 3 Decomposition reaction furnace 4 Substrate 6 Raw material gas outlet 7 Reaction gas introduction line 9 Exhaust system 10 Ring-shaped hot filament 11 Light irradiator

Claims (9)

A film forming material for forming a Si-based film,
The film forming material is
_{t-C 4} H 9 _SiX 3 and (X is any group),
A Si-based film forming material comprising a reactive compound that reacts with the t-C ₄ H ₉ SiX ₃ . _2. The Si-based film forming material according to claim 1, wherein the reactive compound is one or more compounds selected from the group consisting of azides, amines, hydrazines, and H2. The Si-based film forming material according to claim 2, wherein the azide is an alkyl azide. Azide _{CH 3 N 3, C 2 H} 5 N 3, n-C 3 H 7 N 3, i-C 3 H 7 N 3, n-C 4 H 9 N 3, sec-C 4 H 9 N 3 _4. The Si-based film forming material according to claim 2, wherein the Si-based film forming material is one or more compounds selected from the group consisting of tC ₄ H ₉ N ₃ and C ₆ H ₅ N ₃ . X is a hydrogen atom, a halogen atom, an alkoxy group, Si-based film-forming material of claim 1, wherein the alkylamino group, and selected from the group consisting of N ₃ is any. 6. The Si-based film forming material according to claim 1, wherein the Si-based film is a Si film or a SiN film. 7. The film forming material according to claim 1, wherein the film forming material is a material for forming a film by CVD. A Si-based film forming method, comprising forming a Si-based film by supplying the film forming material according to claim 1 onto a substrate. The Si-based film forming method according to claim 8, wherein the film forming material according to claim 1 is supplied onto the substrate in a gas phase state.

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