JPS62190721A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form an impurity diffused layer having a shallow junction by forming a polycrystalline high melting point metal silicide layer on a single crystal substrate at low temperature, and then heat treating it to grow the silicide grains. CONSTITUTION:A W silicide thin film 2 which contains, for example, phosphorus is formed on a single crystal silicon substrate 1. When the substrate is then heat treated, the grains of the W silicide 3 are grown, phosphorus impurity passes the grain boundary to be diffused at high speed and distributed in high density on the surface of the single crystal silicon. The impurity phosphorus atoms accumulated on the surface are slightly diffused in the silicon to form a high density phosphorus shallow diffused layer 4. Thus, the silicide layer to become a diffusion source is accumu lated by containing the impurity in the silicide by CVD or sputtering, the grains of the silicide is grown by heat treating to sweep the impurity existing in the grain boundary to diffuse the impurity in the semiconductor substrate. Accordingly, no defect is formed in the semiconductor single crystal. A high density shallow impurity diffused layer is formed in a region having small diffusion coefficient in the substrate by the thermal diffusion by selecting the temperature and the time of growing the grains of the silicide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for diffusing impurities into a semiconductor single crystal substrate in semiconductor device manufacturing, and is particularly effective in forming an impurity diffusion layer having a shallow junction.

[Summary of the invention]

In the method for manufacturing a semiconductor device of the present invention, after forming amorphous or polycrystalline silicide containing a high concentration impurity in a region where a diffusion layer is to be formed, heat treatment is performed to grow a crane of the silicide, thereby removing the high concentration impurity. is characterized by diffusing into the semiconductor substrate. After forming the P2O layer on the silicide, if heat treatment is performed to diffuse the impurities in the silicide, evaporation of the impurities can be suppressed.
Impurities can be more efficiently diffused into the semiconductor substrate.

[Conventional technology]

Formation of an impurity diffusion layer by a conventional semiconductor device manufacturing method is described in J, Electrochem, Soc, 1145'V
o1131. Yang 5. (1984), after directly implanting impurities into the semiconductor substrate by ion implantation,
This was done by performing annealing.

[Problem that the invention seeks to solve]

However, when impurity ions are directly implanted into a semiconductor substrate, defects occur, and when the impurities are activated by kneeling, accelerated diffusion due to defects occurs by about 500x, making it difficult to form an impurity diffusion layer with a shallow junction. make it difficult In addition, defects caused by ion implantation have a problem in that the crystallinity cannot be completely recovered by the annealing treatment, resulting in slight leakage in the bonding.The purpose of the present invention is to solve the problems of the conventional technology It is an object of the present invention to provide a manufacturing method for impurity diffusion that does not cause defects caused by ion implantation and yet enables the formation of shallow junctions.

[Means for solving problems]

To solve this problem, ion implantation is not performed, but the silicide layer that serves as a diffusion source is impurity-filled and accumulated in the silicide by OVD or sputtering, and the silicide grains are grown by heat treatment to form silicide grains that exist in the grain boundaries. The impurities are swept out and diffused into the semiconductor substrate. Therefore, no defects occur in the semiconductor single crystal.Thermal diffusion is achieved by selecting a region with a small diffusion coefficient in the semiconductor substrate and the humidity and time in which silicide grains grow, forming a highly concentrated shallow impurity diffusion layer. Describing the function of the present invention, silicide containing impurities formed on a semiconductor substrate serves as a diffusion source. In addition, by performing the post-silicide heat treatment at a temperature and time that minimizes the diffusion of impurities in the semiconductor substrate and satisfies the conditions for growing the silicide grains, it becomes possible to form a shallow junction.

[For production]

To describe the effect of the present invention, since impurities are diffused into the semiconductor substrate by thermal diffusion using silicide containing impurities as a diffusion source, defects caused by ion implantation do not occur. In addition, since impurity diffusion is performed by the growth of silicide grains, the diffusion coefficient in the semiconductor substrate is much smaller than that in silicide, so a high concentration and shallow impurity distribution is required in the semiconductor substrate. can be formed.

〔Example〕

One embodiment will be described below.

In FIG. 1, a W silicide thin film 2 containing phosphorus is formed on a single-crystal silicon substrate 1. Next, the substrate is heat-treated at approximately 1050° C. for 10 seconds, resulting in
As the grains of W silicide grow, Linnean particles diffuse at high speed through the grain boundaries and are distributed at high concentration on the single crystal silicon surface.The impurity phosphorus atoms accumulated on this surface are at 1050℃ and 10(6) Then, it spreads slightly into the single crystal silicon, forming a shallow diffusion layer 4 of highly concentrated phosphorus.

FIG. 2 shows the substrate after heat treatment at 1050° C. and 10 seas, which consists of a W silicide 3 with grown grains and a phosphorus diffusion layer 4 with a shallow junction in single crystal silicon 1.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to manufacture a shallow impurity diffusion structure that does not cause defects.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views showing the process of forming a shallow impurity diffusion method according to the present invention. 1... Single-crystal silicon substrate 2... W silicide thin film containing phosphorus 3... W silicide with grown grains 4... Shallow linne thin diffusion layer or more

Claims (1)

[Claims] In a manufacturing method for impurity diffusion into a semiconductor single crystal substrate,
After forming an amorphous or small polycrystalline high melting point metal silicide layer containing impurities on the single crystal substrate at a low temperature, heat treatment is performed to grow the crane of the silicide, thereby diffusing the impurity into the semiconductor substrate. A method of manufacturing a semiconductor device, characterized by: