JPS60171773A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable to realize the target semiconductor device without passing through a process, wherein a P type diffusion layer formed on the side of eigher of both main surfaces of the semiconductor substrate is removed, by a method wherein N type impurities of high concentration are diffused from the surface of the P type diffusion layer formed on the side of the main surface of the semiconductor substrate and the P type diffusion layer is made to invert into an N type diffusion layer. CONSTITUTION:P type impurities, such as Ga impurities, are thinly diffused from the side of both main surfaces of an N type semiconductor substrate 11 for forming a P type layer 12a and a P type layer 12b. At this time, an SiO2 film 13, with which the whole of the semiconductor substrate 11 is covered, is simultaneously formed by performing a heat oxidation. After the SiO2 film 13 on the side of one main surface of the semiconductor substrate 11, such as the SiO2 film 13 on the side of the P type layer 12a, was removed, N type impurities, such as P impurities of high concentration, are diffused from both main surfaces of the semiconductor substrate 11. In this case, when the P impurities are diffused for a prescribed time, the P type layer 12a is made to invert into an N<+> type layer due to the difference between the diffusion rates in both main surfaces of the semiconductor substrate 11, because the concentration of the P impurities is high. Then, a drive-in heating process is performed, and after that, an N<+> type layer 14' of the target diffusion depth which penetrates the P type layer 12a is obtained. After this, various treatments are performed and the target diode pellet is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device that can simplify the manufacturing process and reduce manufacturing costs.

[Technical landscape of invention and its problems]

When manufacturing a large-capacity, high-voltage semiconductor device, such as a diode, the following method has conventionally been used.

That is, FIG. 1 is a process diagram showing the above manufacturing method, in which first, as shown in the same apparatus, P-type layers (2a) and (2b) are formed on an N-type semiconductor substrate (1) from its ambidextrous surface. Therefore, a PfJl impurity such as gallium (Ga) is diffused.

Next, as shown in Figure (B), a silicon dioxide film (SiO□ film) (3) is formed by a thermal oxidation method, and then
), for example, among the P-type layers (2a) and (2b) on one main surface side of the semiconductor substrate (1), the P-type layer (2a) is removed.

When carrying out the above process, from the standpoint of productivity improvement, two sheets of wafer are usually pasted together with wax or the like with the side to be wrapped outward, and the thickness of the sheets is measured.
Alternatively, the P-type layer (2
We are trying to eliminate a). After that, as shown in FIG.
spread.

Next, as shown in the same figure (G), drive-in heating is performed to obtain N diffusion layers (4) of the target depth, and then various treatments are performed according to well-known methods to form the target diode pellet. obtain.

However, in the above manufacturing method, the P-type layer (2
The process of removing a) is complicated and takes a long time, which is one of the reasons for the rise in product costs.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and provides a method for manufacturing a semiconductor device that allows a target semiconductor device to be obtained without going through the step of removing the P-type layer on the entire surface side of a semiconductor substrate. The purpose is to

[Summary of the invention]

The present invention enables the P-type diffusion layer formed on one of the main surfaces of the semiconductor substrate to be removed without removing it by lapping or the like.
This method of manufacturing a semiconductor device simplifies the manufacturing process and reduces manufacturing costs by diffusing N-type impurities with a bacterial concentration from above the type diffusion layer and inverting it to the N-type diffusion layer.

[Embodiments of the invention]

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

FIG. 2 is a process diagram showing a method of manufacturing a semiconductor device according to the present invention.

First, as shown in the same apparatus, in order to form P-type layers (12a) and (12b) from the bidirectional side of an N-type semiconductor substrate (11), a P-type impurity, for example, Ga is applied thinly, for example, to a depth of about 10 μm.
Diffuse to some extent. The impurity concentration of Ga at this time is approximately 1016
~1019 atoms/cJ.

At this time, a 5i02 film (13) covering the entire semiconductor substrate (11) is simultaneously formed by thermal oxidation.

Next, as shown in the same figure (B), the 5i02 film (1
3) is removed by a known method.

Further, as shown in FIG. 2C, the P-type layer on the side from which the 5i02 film (13) has been removed is inverted and an N-type impurity, for example, P (IJn), is diffused to form an N-type layer. in this case,
The impurity concentration of P is approximately 1019 to 10” atoms/C
Since the impurity concentration of Ga used to form the P-type layer (12) is sufficiently high compared to 1016 to 1019 atoms/c111, when the p-type layer (12a) is diffused for a predetermined time, the p-type layer (12a ) in one layer (14)
invert it. Thereafter, through the drive-in heating process shown in FIG. 3(C), the P-type layer (12g) is penetrated to obtain the N+ layer (14') having the target diffusion depth.

Hereafter, the target diode pellet (f4'J) is produced through known processing steps in the same manner as in the prior art.

〔Effect of the invention〕

As described above, the present invention does not require removing the P-type layer on the surface side of the semiconductor substrate using a lapping machine or the like, but instead converts the entire P-type layer into an N-type layer by diffusing N-type impurities of the opposite 4-voltage type. This eliminates the need for the complicated and time-consuming removal step, which simplifies the manufacturing process of semiconductor devices and significantly reduces manufacturing costs.

[Brief explanation of the drawing]

11th! n(A) to (G) are process diagrams showing an example of a conventional method for manufacturing a semiconductor device, and FIGS. 2(4) to 0 are process diagrams showing an example of a method for manufacturing a semiconductor device according to the present invention. be. 11...N-type semiconductor substrate, 12a112b-P-type layer, 13...SiO□ film 14.14'...N-type layer. Applicant: Japan International Seiichi Co., Ltd. No. 1
Figure 2

Claims (1)

[Claims] A step of diffusing P-type impurities from both sides of an N-type semiconductor substrate to form a P-type layer on the side of the both sides, and a step of forming a P-type layer on one of the above-mentioned P-type layers. A method for manufacturing a semiconductor device, comprising the step of diffusing a high concentration N-type impurity having a sufficient impurity concentration to penetrate through this P-type layer and invert it to an N-type.