JPS635518A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To perform a high density impurity doping on the first and the second semiconductor layers by a method wherein, after impurities have been coated on the surface of the first semiconductor layer, the second semiconductor layer is formed on the impurities, and the impurities are diffused on the first and the second semiconductor layers from between the two layers. CONSTITUTION:After an impurity coating liquid 12A has been coated on the surface of the first semiconductor layer (silicon substrate) 2, the second semiconductor layer (polysilicon layer) 10 is formed on said impurity coating liquid 12A. Then, the impurity coating liquid 12A, coated on the first and the second semiconductor layers 2 and 10 from between the two layers, is diffused. As a result, a high density doping can be made possible, and the impurity density can be increased on the region ranging from the boundary region of the first and the second semiconductor layers 2 and 10 toward the first and the second semiconductor layers 2 and 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device in which impurities are applied and diffused in a semiconductor layer, and particularly relates to high concentration doping.

[Conventional technology]

Conventionally, a doped poly method as shown in FIG. 3 has been used as a method for manufacturing semiconductor devices in which a polycrystalline layer is formed as an electrode. For example, a P-type conductive region 4 is formed on the surface of an N-type silicon substrate 2, an oxide film 6 covering the surface portion is selectively removed to form an opening 8, and then a polysilicon layer covering the opening 8 is formed. form 10. An impurity coating liquid 12 made of an organic coating agent containing impurities is applied to the surface of the polysilicon layer 10, and the impurities are diffused from the polysilicon layer 10 into the conductive region 4 of the silicon substrate 2 as shown by arrow a. to reach the polysilicon layer 10 into the conductive region 4
It is formed as an ohmic contact as an electrode.

[Problem that the invention seeks to solve]

By the way, when the impurity coating liquid 12 is applied to the surface of the polysilicon layer 10 in this way and the impurity is diffused into the surface of the polysilicon layer 10, the impurity concentration in the polysilicon layer 10 and the conductive region 4 of the silicon substrate 2 is The distribution is
As shown at 0 in FIG. 4, the concentration is high in the polysilicon layer 10, and as shown in P in FIG. 4, the concentration is extremely low on the surface of the silicon substrate 2, increasing the concentration in the conductive region 4. I can't.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device in which the impurity diffusion concentration is increased in a semiconductor layer in which impurities are diffused.

[Means for solving problems]

As shown in FIG. 1, the method for manufacturing a semiconductor device of the present invention involves coating the surface of a first semiconductor N (silicon substrate 2) with an impurity (impurity coating liquid 12A), and then applying the impurity (impurity coating liquid 12A) to the surface of the first semiconductor N (silicon substrate 2). ), a second semiconductor N (polysilicon layer 10) is formed on the first and second semiconductor layers (silicon substrate 2 and polysilicon N10), and an impurity (impurity coating liquid 12A) is applied between the first and second semiconductor layers (silicon substrate 2 and polysilicon N10). ).

[For production]

In this way, unlike the conventional method of applying an impurity (impurity coating liquid 12) to polysilicon JILO and diffusing the impurity into the silicon substrate 2, the first and second semiconductor layers (silicon substrate 2 and Since the impurity (impurity coating liquid 12A) is diffused between the polysilicon layer 10),
High concentration doping becomes possible, and the impurity concentration can be increased from the boundary region between the first and second semiconductor layers toward the first and second semiconductor layers.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the method for manufacturing a semiconductor device of the present invention.

This embodiment is a method of forming a polysilicon layer as an electrode, similar to the method of manufacturing a semiconductor device shown in FIG.

As shown in FIG. 1A, a P-type conductive region 4 is formed on the surface of an N-type silicon substrate 2, and an opening 8 is formed by selectively removing the oxide film 6 covering the surface portion. This opening 8
The impurity coating liquid 12A is applied to cover the substrate. This impurity coating liquid 12A uses, for example, an organic coating agent containing an impurity such as boron.

Next, as shown in B of FIG. 1, polysilicon N10 is formed on the surface of the silicon substrate 20 coated with the impurity coating liquid L2A, and then, as shown in C of FIG. Also, an impurity coating liquid 12B similar to the impurity coating liquid 12A is applied and a heat treatment is performed.

As a result, as shown in FIG. 1C, the impurity coating liquid 12
A causes the impurities to be diffused in the directions shown by arrows a and b, and the impurity coating liquid 12B causes the impurities to be diffused in the directions shown by arrow C and can reach the conductive region 4 of the silicon substrate 2. As a result, As shown in FIG. 1D, polysilicon layer 10 is formed as an electrode by diffusion of impurities.

Therefore, if this is done, the impurity concentration distribution in silicon substrate 2 and polysilicon layer 10 will become as shown by X in FIG. That is, the polysilicon layer lO
A high concentration distribution is obtained over a wide range from region 0 to the conductive region 4 indicated by region P, and the impurity concentration distribution on the silicon base vi2 side can be improved, and the polysilicon layer 10 can be made to have high conductivity. It can be formed as an electrode.

In the example, the impurity coating liquid 12B was placed on the surface of the polysilicon 1110, but if this was omitted, the impurity concentration would be as shown by Y in FIG.
0 and the conductive region 4 exhibits a concentration distribution with a large point. Even with such an impurity concentration, polysilicon layer 10 can be formed as an electrode.

Further, although an N-type silicon substrate was used in the embodiment, the present invention can be similarly realized using a P-type silicon substrate or a substrate made of other semiconductor layers, and the impurities may be other than boron. It can be applied in the same way.

〔Effect of the invention〕

As described above, according to the present invention, impurities can be directly doped into the first and second semiconductor layers from between the first and second semiconductor layers, and
In addition, the second semiconductor layer can be doped with impurities at a high concentration, and for example, the second semiconductor layer can be formed as an ohmic contact as an electrode with respect to the first semiconductor layer.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the method for manufacturing a semiconductor device of the present invention, FIG. 2 is a diagram showing the impurity concentration when the method for manufacturing the semiconductor device shown in FIG. 1 is implemented, and FIG. 3 is a diagram showing the conventional semiconductor device. FIG. 4 is a diagram showing the impurity concentration when the method for manufacturing the semiconductor device shown in FIG. 3 is carried out. 2... Silicon substrate as a first semiconductor layer, 10.
...Polysilicon layer as a second semiconductor layer, 12A,
12B... Impurity coating liquid. Figure 2 and Figure 1

Claims (1)

[Claims] After applying an impurity to the surface of the first semiconductor layer, a second semiconductor layer is formed on the impurity, and the impurity is diffused into the first and second semiconductor layers from between the two. A method for manufacturing a semiconductor device.