JP2647304B2 - Coating solution for forming dopant diffusion film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid for forming a novel dopant diffusion film used in a semiconductor device manufacturing process.
More particularly, the present invention relates to a coating liquid for forming a dopant diffusion film capable of forming a thick film for uniformly and highly diffusing a dopant in a semiconductor substrate.

[0002]

2. Description of the Related Art It is well known that p-type or n-type conductive impurity regions are formed by various diffusion methods in the manufacture of semiconductor devices. As this diffusion method, for example, a gas diffusion method, a solid diffusion method, an ion implantation method, or the like is performed, and in particular, a variation in a dopant (impurity) diffused into a semiconductor substrate adversely affects characteristics of a semiconductor element. For this reason, a doped oxide method with less variation in the dopant diffusion concentration is often used.

In the doped oxide method, various oxides serving as dopants are grown on a semiconductor substrate by a CVD technique, and the dopants are diffused into the semiconductor substrate by a thermal diffusion process using these doped oxides as a dopant diffusion source layer. Is the way. However, the doped oxide method has a small variation in the concentration of the dopant diffused into the semiconductor substrate, and is excellent in homogeneity, but requires an expensive CVD apparatus and has poor productivity and is suitable for mass production. It is not a practical method because it has disadvantages such as not being able to perform high-concentration diffusion.

On the other hand, as a coating diffusion method, there is known a method using a coating liquid for forming a dopan-containing silica-based film in which an organic solvent solution of a silicon compound such as halogenated silane or alkoxysilane contains a dopant diffusing agent. . However, although this method is advantageous in terms of equipment cost, etc., the concentration of the dopant diffused into the semiconductor substrate tends to vary, and a thick film is hardly formed, and a high-concentration dopant diffusion region cannot be formed. It has disadvantages such as.

[0005]

SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of the prior art, does not require expensive equipment as in the CVD method, and allows the dopant to be uniformly and highly concentrated in a semiconductor substrate. The purpose of the present invention is to provide a coating solution for diffusing into a liquid.

[0006]

The present inventors have conducted various studies on a coating solution for diffusing a dopant into a semiconductor substrate, and as a result, have found that a solution of polysilazane or a silazane compound capable of forming polysilazane by heat treatment is obtained. The present inventors have found that the use of a coating liquid containing a dopant diffusing agent at a predetermined ratio allows the dopant to be diffused uniformly and at a high concentration in the semiconductor substrate, and the present invention has been completed based on this finding.

That is, the present invention provides (A) a dopant diffusing agent and (B) a polysilazane or a silazane compound capable of forming a polysilazane by heat treatment at a weight ratio of 1: 1.
To provide a coating liquid for forming a dopant diffusion film, which is contained at a ratio of 1:10.

In the coating solution of the present invention, the dopant diffusing agent used as the component (A) is compatible with the component (B) and soluble in a solvent to form a film.
A compound that is hardly affected by the outside air (a compound having a strong hygroscopic property is difficult to handle due to stickiness) and has a low sublimation property even at a high temperature during diffusion.

Compounds satisfying such conditions include:
For example, (RO) ₃ P, (RO) ₂ P (OH), (RO)
₃ PO, (RO) ₂ P ₂ O ₃ (OH) ₃ , (RO) P
Phosphorus compounds such as (OH ₂ ), B ₂ O ₃ , (RO)
Boron compounds such as ₃ B, RB (OH) ₂ , R ₂ B (OH), H ₃ SbO ₄ , (RO) ₃ Sb, SbX ₃ , Sb
OX, antimony compounds such as Sb ₄ O ₅ X, H ₃ As
O ₃ , H ₂ AsO ₄ , (RO) ₃ As, (RO) ₅ A
s, (RO) ₂ As (OH), R ₃ AsO, RAs = A
Arsenic compounds such as sR, Zn (OR) ₂ , ZnX ₂ , Z
zinc compounds such as n (NO ₂ ) ₂ , (RO) ₃ Ga, R
Ga (OH), RGa (OH) ₂ , R ₂ Ga [OC (C
_{H 3) = CH-C (} CH 3) = O ] gallium compounds such _{as, HAuCl 4, AuX 3, R} 2 AuX, R 2 Au
And a gold compound such as [OC (CH ₃ ) ＣＨCH—CO (CH ₃ )] (where R is a halogen atom, an alkyl group, an alkenyl group or an aryl group, and X is a halogen atom). These dopant diffusing agents may be used alone or in combination of two or more.

In the coating solution of the present invention, polysilazane or a silazane compound capable of forming polysilazane by heat treatment is used as the component (B). The silazane compound is a general term for compounds having a Si—N bond in the molecule, but in the present invention, it is preferable to use a silazane compound containing no oxygen atom in the molecule.

Such a silazane compound is a halogeno compound.
Orchid or organohalogenosilane and ammonia or amine
With an organic solvent in an organic solvent.
You. As the halogenosilane used at this time, for example,
SiCl₄, HSiCl₃, H₂SiCl₂, H₃Si
Cl and the like, and an organohalogen
As the silane, for example, CH₃SiHCl₂, CH₃
SiH₂Cl, CH₃SiCl₃, (CH₃)₂SiC
l₂, (CH₃)₃SiCl, C₂H₅SiCl₃,
(C₂H₅)₃SiCl, (C₂H₅) (C₆H₅) S
iCl₂, (C₂H₅) (C₆H₅)₂SiCl, (C
H₃)₃CSiHCl₂, (CH₃)₂CHSiHCl
₂, (C₆H₅) SiHCl₂, (C₆H₅) SiCl
₃, (C₆H ₅)₂SiCl₂, (C₆H₅)₃SiC
l, C₆H₅CH₂SiCl₃, (C₆H₅CH₂)₂
SiCl₂, (C₆H₅CH₂)₃SiCl etc.
Can be

On the other hand, examples of amines to be reacted with these halogenosilanes and organohalogenosilanes include lower alkylamines such as monomethylamine, ethylamine, propylamine and butylamine, polyamines such as ethylenediamine, and aralkylamines such as benzylamine and phenethylamine. And the like.

The organic solvents used in these reactions include, for example, toluene, xylene, diethyl ether,
Dichloromethane and the like.

Particularly preferred silazane compounds are those obtained by dissolving a halogenosilane such as HSiCl ₃ , H ₂ SiCl ₂ , or H ₃ SiCl in the organic solvent, and blowing ammonia gas into the solution.

In the present invention, the reaction mixture of the thus obtained halogenosilane or organohalogenosilane and ammonia or amines may be used as such in the coating solution, or the reaction mixture may be subjected to distillation under reduced pressure or the like. After removing the solvent and recovering the desired silazane compound as an oily substance or a solid substance, this may be dissolved in an appropriate organic solvent and used in the coating solution, or the silazane compound may be previously heat-treated. Polysilazane may be formed, and this may be dissolved in an appropriate organic solvent and used in the coating solution.

The weight ratio of component (A) to component (B) in the coating solution of the present invention is 1: 1 to 1: 1.
It is necessary to select in the range of 0. If the amount of the component (A) is less than the above range, the dopant cannot be diffused at a high concentration. If the amount is more than the above range, it is difficult to form a uniform coating, and the object of the present invention cannot be sufficiently achieved.

The coating solution of the present invention contains 1 to 60% by weight, preferably 10 to 3% by weight of polysilazane or a silazane compound.
Those containing 0% by weight are practically suitable.

Next, the method of using the coating liquid for forming a dopant diffusion film according to the present invention will be described. First, a conventional method such as a spinner method, a spray method, a dipping method, or a brush coating method is used on a semiconductor substrate. After applying the coating solution, the coating solution is baked at a temperature of about 200 to 600 ° C. for about 10 minutes to 2 hours to form a dopant-containing polysilazane film, and then at a temperature of about 1100 to 1300 ° C.
Diffusion of the dopant is performed by heat treatment for about a minute to 4 hours.

As described above, the dopant is uniformly diffused into the semiconductor substrate, and a semiconductor substrate having p-type or n-type conductive impurity regions formed thereon can be easily obtained.

[0020]

The coating liquid for forming a dopant diffusion film according to the present invention can easily form a thick dopant-containing polysilazane film capable of uniformly and highly diffusing a dopant in a semiconductor substrate.

By using the coating solution, it is possible to easily form a high-concentration homogeneous dopant diffusion region in a semiconductor substrate without using expensive equipment as in the CVD method. The target value is extremely high.

[0022]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1 5 g of trimethylsilyl polyphosphate was added to 5 g of a 20 wt% xylene solution of a reaction product of dichlorosilane and ammonia, and the mixture was thoroughly stirred to prepare a coating solution for forming a phosphorus diffusion film.

Next, the coating solution is applied onto a p-type silicon wafer having a specific resistance of 10 to 20 Ω · cm using a spinner rotated at 3000 rpm.
It was baked at 500 ° C. for 30 minutes in air. Next, this was subjected to a diffusion treatment at 1200 ° C. for 60 minutes while flowing nitrogen gas and oxygen gas at a rate of 2.85 l / min and 0.15 l / min, respectively. The sheet resistance at that time was 0.9Ω / □.

Example 2 To 5 g of a 20 wt% xylene solution of a reaction product of dichlorosilane and ammonia, 5 g of tributoxy arsenic was added.
The mixture was thoroughly stirred to prepare a coating solution for forming an arsenic diffusion film.

Next, the above coating solution is applied onto a p-type silicon wafer having a specific resistance of 10 to 20 Ω · cm by using a spinner rotated at 3000 rpm.
It was baked at 500 ° C. for 30 minutes in air. Next, this was subjected to a diffusion treatment at 1250 ° C. for 2 hours while flowing nitrogen gas and oxygen gas at a rate of 2.85 l / min and 0.15 l / min, respectively. The sheet resistance at that time is 1
It was 5Ω / □.

Claims (1)

(57) [Claims] 1. A dopant diffusion coating comprising (A) a dopant diffusing agent and (B) a polysilazane or a silazane compound capable of forming a polysilazane by heat treatment at a weight ratio of 1: 1 to 1:10. Forming coating solution.