JPH02244636A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive the fine formation of a bipolar transistor and an increase in the uniformity of the characteristics of the transistor by a method wherein an external base, an internal base and an emitter are formed in a self-alignment manner to a field oxide film. CONSTITUTION:A field oxide film 2 and a P-type polycrystalline Si layer 3, subsequently, a CVD oxide film 4 are formed on an N-type substrate 1. Then, the film 2, the layer 3 and the film 4 are simultaneously subjected to selective etching and removed to form an opening part. Then, boron is diffused in the substrate 1 through a P-type polycrystalline Si layer 5 selectively formed on the sidewall of the opening part to form an external base region 6 in a self- alignment manner to the film 2. Then, after an oxide film 7 is formed in the opening part, boron is implanted in the substrate 1 using the layer 5 as a mask to form an internal base region 8. Then, after a CVD oxide film 9 is formed on the whole surface, a polycrystalline Si layer 10 is selectively formed and moreover, a polycrystalline Si layer 11 is grown and arsenic is diffused to form an emitter region 12.

Description

[Detailed Description of the Invention] [Summary] An object of the present invention is to provide a method for manufacturing a bipolar transistor, in which an external base, an internal base, and an emitter are formed in a self-aligned manner with respect to a field oxide film. A step of selectively etching and removing a multilayer film formed on the substrate, consisting of a field oxide film, polycrystalline SiN of opposite conductivity type, and an insulating film to form an opening, and selectively etching a sidewall of the multilayer film of the opening. forming an external base region by diffusing an opposite conductivity type impurity into the substrate from the first opposite conductivity type polycrystalline Si layer formed in the first opposite conductivity type polycrystalline silicon layer; A step of implanting impurities of opposite conductivity type into the substrate using the polycrystalline Si layer as a mask to form an internal base region in contact with the external base region, and after depositing an insulating film on the entire surface, a second polycrystalline silicon layer is deposited on the side wall of the opening. A step of selectively forming a Si layer and using this as a mask to etch and remove the oxide film in the opening to form a second opening; An emitter region is formed by diffusing impurities of one conductivity type into the substrate.

[Industrial Field of Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing a bipolar transistor using self-alignment.

[Conventional technology]

In order to increase the speed of bipolar transistors, it is necessary to miniaturize the pattern dimensions of each part of the transistor and reduce the positional deviation between the patterns.
It is running. FIGS. 2(a) to 2(d) are process cross-sectional views for explaining a conventional example.

First, as shown in FIG.
After forming a field oxide film 22, the p-type polycrystalline Si layer 23 and CVD oxide film 24 deposited on the entire surface are selectively etched and removed using a normal photoresist method to create an opening in the element region. Form. Furthermore, p type polycrystalline S
An n-type impurity is diffused into the substrate 21 from the i-layer 23 to form an external base region 25. P′ type polycrystalline Si layer 23
functions as an extraction electrode of the external base region 25 as it is. Next, as shown in FIG. 0), after a thermal oxide film 25a is formed in the opening, an n-type impurity is implanted into the opening by ion implantation to form an internal base region 26.

Next, as shown in FIG. 2C, after depositing a CV'D oxide film 27 on the entire surface, the CVD oxide film 27 on the side wall of the opening is deposited.
A P' type polycrystalline Si layer 28 is selectively formed thereon. Next, as shown in the same figure (d), the polycrystalline Si layer 2 on the side wall of the opening is
8 as a mask, the thermal oxide film 25a and C in the internuclear "] part
The VD oxide film 27 is removed by etching to form a window, and an emitter region 30 is formed by diffusing n-type impurities from the n-type polycrystalline S layer 29 formed thereon.

Through the above steps, the emitter region 30 is formed into the internal base region 2.
6 can be formed in a self-aligned manner.

(Problems to be Solved by the Invention) However, in the above method, the external base region is formed by patterning the field oxide film by normal mask alignment, and is not formed in a self-aligned manner. Therefore, it is necessary to increase the width of the external base region in consideration of positional deviation during mask alignment. This not only greatly hinders miniaturization of the entire bipolar transistor, but also causes non-uniformity in transistor characteristics due to variations in the external base width.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming an external base, an internal base, and an emitter in a self-aligned manner with respect to a field oxide film, thereby achieving miniaturization and uniformity of characteristics of bipolar transistors.

(Means to Solve the Problem) The above problem can be solved by selectively etching and removing a multilayer film formed on a substrate of one conductivity type, consisting of a field oxide film, a polycrystalline Si layer of an opposite conductivity type, and an insulating film. forming an opening, and diffusing an opposite conductivity type impurity into the substrate from a first opposite conductivity type polycrystalline Si layer selectively formed on the sidewall of the multilayer film of the opening, thereby forming an external base region. forming an oxide film in the opening, and then implanting an opposite conductivity type impurity into the substrate using the first polycrystalline 5iJFJ as a mask to form an internal base region in contact with the external base region; After depositing an insulating film over the entire surface, a second polycrystalline Si layer is selectively formed on the side wall of the opening, and using this as a mask, the oxide film within the opening is etched and removed to form a second opening. and forming an emitter region by diffusing one conductivity type impurity into the substrate from the one conductivity type polycrystalline Si layer formed in the second opening. achieved by the method.

[For production]

A feature of the present invention is that openings are formed by selectively etching a multilayer film consisting of a field oxide film, a polycrystalline Si layer of opposite conductivity type, and an insulating film at the same time using the same mask. By doing this, the external base region formed using the first polycrystalline Si layer formed on the side wall of the opening as a diffusion source is formed in self-alignment with the field oxide film for element isolation, and this external base region is formed in a self-aligned manner with respect to the field oxide film for element isolation. The width of the base region is the first polycrystalline S
It becomes possible to make it extremely fine, which is determined by the thickness of the i-layer. Furthermore, the external base region can be connected to the polycrystalline SR layer of the opposite conductivity type on the field oxide film through the first polycrystalline Si layer and drawn out to the outside without going through any special process. As described above, the internal base region and the emitter region are formed in a self-aligned manner with respect to the formed external base region, and their widths can be made extremely fine.

〔Example〕

FIGS. 1(a) to 1(d) are process cross-sectional views showing an embodiment of the present invention.

As shown in Figure (a), first, a field oxide film 2 with a thickness of 1 μm was formed on an n-type Si substrate) using a normal thermal oxidation method, and boron (B) was doped thereon. membrane 70
．． 3 μm p” type polycrystalline 5ii3, followed by 0.5 μm film thickness
A CVD oxide film 4 having a thickness of m is formed. Next, the field oxide film 2, the P'-type polycrystalline Si layer 31, and the CVD oxide film 4 are selectively etched and removed simultaneously to form an opening with a width of 0.8 μm. Next, the entire surface is doped with boron and the film thickness is 0.
．． When a 3 μm p'-type polycrystalline Si layer is grown, the entire surface is etched by the RUE method, and the p'-type polycrystalline Si layer 5 is left only on the side wall of the opening, the p'-type polycrystalline Si layer 5 is heat-treated.
Boron is diffused into substrate 1 using layer 5 as a diffusion source, and external base region 6 is formed in self-alignment with field oxide film 2. Next, as shown in FIG. 2B, the p'-type polycrystalline Si layer 5 and the substrate surface within the opening are oxidized to form a thin oxide film 7. Furthermore, boron is implanted into the internal base region 8 through the oxide film 7 by ion implantation.
form. Next, as shown in FIG. 3(C), after forming a CVD oxide film 9 on the entire surface, a polycrystalline 34 layer 10 is formed on the side wall of the opening by the method described above, and using this as a mask, the oxide film on the opening is formed. 7 is etched and removed. Next, as shown in FIG. 2D, a polycrystalline Si layer 11 is grown, and arsenic (As) is implanted and heat treated to form an emitter region 12 in a self-aligned manner with respect to the internal base region 8. As shown in FIG. 2D, the polycrystalline Si layer 3 is connected to the external base region 6 via the polycrystalline Si layer 5 on the side wall of the opening, and functions as a base wire.

〔Effect of the invention〕

As described above, according to the present invention, an external base, an internal base, and an emitter can be formed in a self-aligned manner without using a mask on a field oxide film, so that pattern dimensions can be miniaturized. , which is extremely useful in increasing the speed of bipolar transistors.

[Brief explanation of drawings]

FIGS. 1(a) to (d) are process cross-sectional views showing an embodiment of the present invention, and FIGS. 2(a) to (d) are process cross-sectional views showing problems in the conventional example. In the figure, 1, 21 is a substrate of one conductivity type, 2.22 is a field oxide film, 3.23 is a polycrystalline Si layer of an opposite conductivity type, 4.9, 24, 27 is an insulating film, and 5 is a first opposite conductivity type. type polycrystalline Si layer, 6.25 is an external base region, 7 is an oxide film, 8.26 is an internal base region, 10 is a second opposite conductivity type polycrystalline Si layer, 11.29 is one conductivity type polycrystalline Si layer 12.30 is an emitter region, 25a is a thermal oxide film, and 28 is a polycrystalline Si layer.

Claims (1)

[Claims] A field oxide film (
2), opposite conductivity type polycrystalline Si layer (3) and insulating film (4)
forming an opening by selectively etching and removing a multilayer film made of External base region (6) by diffusing type impurities into the substrate (1)
After forming an oxide film (7) in the opening, impurities of opposite conductivity type are implanted into the substrate (1) using the first polycrystalline Si layer (5) as a mask to form the external base. After forming an internal base region (8) in contact with the region (6) and depositing an insulating film (9) on the entire surface, a second polycrystalline Si layer (10) is selectively formed on the side wall of the opening. Then, using this as a mask, the oxide film (7) in the opening is etched and removed to form a second opening, and the polycrystalline Si layer (11) of one conductivity type formed in the second opening is etched and removed. 1. A method for manufacturing a semiconductor device, comprising the step of forming an emitter region (12) by diffusing impurities of one conductivity type from ) into a substrate (1).