JPH02268440A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a required emitter lower layer electrode with a good reproducibility by selectively growing silicon only in an opening for an emitter contact and adding an impurity to form the emitter lower layer electrode. CONSTITUTION:A silicon oxide film 3 and a silicon nitride film 4 are formed on a silicon substrate 1 in which base regions 2 are selectively formed. Openings are made in the silicon nitride film 4 with a resin film 5 used as a mask. The silicon nitride film 4 is covered by a resin film 6 having only an opening for an emitter contact and only opening for the emitter contact is made in the silicon oxide film 3 with the resin film 6 and the silicon nitride film 4 used as masks. Both the resin films, 5 and 6 are removed, a polycrystalline silicon film 7 is grown, and at the same time an impurity is added. The polycrystalline silicon film 7 is formed with a good reproducibility as an emitter lower layer electrode. An opening for a base contact is made and an emitter region 9 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing a bipolar transistor with a fine structure.

[Conventional technology]

Conventionally, in the manufacturing method of this type of semiconductor device, when a hole formed in an insulating film on a semiconductor substrate is filled with polycrystalline silicon to form a lower emitter electrode, a polycrystalline silicon film is formed on the entire surface. Furthermore, a method has been proposed in which the opening is covered with a resin film and etched using an etching back method to fill the opening with polycrystalline silicon. For example, patent application 1986-1
No. 50785.

FIGS. 3(a) to 3(d) show examples in which the above-described method is applied to bipolar transistors.

First, as shown in FIG. 3(a), a first insulating film 3 and a second insulating film 4 are formed on a silicon substrate 1 forming a base region 2, and then a resin film (not shown) is used as a mask. Openings are formed in the insulating film 3.4 by reactive ion etching.

Subsequently, a polycrystalline silicon film 12 is formed on the entire surface using the CVD method.
grow. At this time, phosphorus (P) or arsenic (As) is added into the polycrystalline silicon film 12 as an impurity to serve as an emitter diffusion source. Furthermore, a resin film 13 is formed on the polycrystalline silicon film 12.

Next, as shown in FIG. 3(b), the resin film 13 and the polycrystalline silicon film 12 are sequentially etched using a reactive ion etching method to form a polycrystalline silicon film only within the openings of the insulating films 3 and 4. Leave 12.

Next, as shown in FIG. 3(C), only the polycrystalline silicon film 12, which will become the lower electrode for forming the emitter region, is removed from the resin film 1.
4 and cover the polycrystalline silicon film 12 in the opening for the base electrode.
is removed by etching using a hydrofluoric acid or nitric acid solution. As a result, the polycrystalline silicon film 12 is left only in the opening corresponding to the emitter, and will later be configured as an emitter lower layer electrode.

Next, as shown in FIG. 3(d), after removing the resin film 14 in oxygen plasma, heat treatment is performed at high temperature to remove impurities in the remaining polycrystalline silicon film 12 on the emitter side from the base region. 2 to form an emitter region 9.

(Problems to be Solved by the Invention) In the conventional manufacturing method described above, if variations occur in the thickness of the polycrystalline silicon film 12 or the resin film 13, the thickness of the film to be etched will vary depending on the thickness of the wafer surface. For this reason, the polycrystalline silicon film 12
In the step of FIG. 3(b) in which the resin film 13 and the resin film 13 are etched at the same time, the fourth
As shown in the figure, under-etching and over-etching occur in the polycrystalline silicon film 12. Further, in some cases, abnormal etching may occur such that the etching rate of the polycrystalline silicon film 12 is higher than that of the resin film 13.

Therefore, in the conventional manufacturing method, it is difficult to properly leave the polycrystalline silicon film 12 in the opening corresponding to the emitter, and it is difficult to form a desired emitter region 9 or a suitable emitter lower layer electrode with good reproducibility. The problem is that it cannot be done.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device, which makes it possible to form an emitter region well and form a suitable lower emitter electrode.

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention includes the steps of forming first and second insulating films on a semiconductor substrate on which a base region is formed, and etching the second insulating film at locations corresponding to the emitter contact and the base contact. etching the first insulating film at the emitter contact location to form an opening exposing the surface of the semiconductor substrate; and etching silicon containing impurities in the emitter contact opening. a step of etching the first insulating film at the base contact portion; a step of diffusing impurities from the emitter lower electrode to form an emitter region; forming an emitter electrode and a base electrode on the emitter contact and the base contact, respectively.

In this case, the emitter lower electrode may be formed by growing impurity-free silicon and then implanting impurities into the silicon by ion implantation or thermal diffusion.

[Effect]

In this manufacturing method, the emitter lower layer electrode can be formed by selectively growing silicon only in the opening for the emitter contact. can be manufactured with good reproducibility.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of a bipolar transistor manufactured by the manufacturing method of the present invention.

In FIG. 1, a base region 2 and an emitter region 9 are formed on a silicon substrate 1, and a silicon oxide film 3. In the insulating film made of silicon nitride film 4, openings for base contact and emitter contact are formed adjacently. Then, an impurity-doped polycrystalline silicon film 7 is formed inside the emitter contact opening, and this is configured as an emitter lower layer electrode.

Further, an emitter electrode 1 is placed on this emitter lower layer electrode 7.
0 is formed, and a base electrode 11 is formed in the base contact opening.

FIGS. 2(a) to 2(e) are cross-sectional views showing the method for manufacturing the bipolar transistor shown in FIG. 1 in order of steps.

First, as shown in FIG. 2(a), a silicon oxide film 3 is formed as a first insulating film on a silicon substrate 1 on which a base region 2 has already been selectively formed, and a second insulating film is further formed on this. A silicon nitride film 4 is formed. Then, using the resin film 5 as a mask, portions corresponding to the emitter contact and the base contact are selectively etched by reactive ion etching to form openings in the second insulating film 4. At this time, the first
The insulating film 3 may be etched to some extent.

Next, as shown in FIG. 2(b), the silicon substrate 1 is covered with a resin film 6 in which only the emitter contact openings are opened.
Using the resin 116 and the second insulating film 4 as a mask, the first insulating film 3 is selectively etched by reactive ion etching or an HF solution to open only the emitter contact. At this time, the resin film 5 used as a mask is first removed and the resin film 6 is formed later, but in some cases, the resin film 5 is left as is and only the base contact opening is covered with the resin film 6. You can do it like this.

Next, as shown in FIG. 2(C), all of the resin films 5 and 6 are
2. Remove using plasma. Then, for example, S i
-MBE (Silicon molecular
beampitaxy: molecular beam epitaxy)
A polycrystalline silicon film 7 is grown at about 450° C. using a method such as the following. At this time, since the polycrystalline silicon film 7 is grown only on the silicon crystal surface, it is grown only inside the emitter contact opening. At this time, arsenic or antimony (sb, etc.) as an emitter diffusion source is added at the same time. This polycrystalline silicon film 7 is configured as an emitter lower layer electrode.

Next, as shown in FIG. 2(d), resin II with only the opening for the base contact opened! 8 as a mask, the first insulating film 3 in the base contact hole is removed by reactive ion etching and an HF solution to form a base contact hole.

Then, as shown in FIG. 2(e), after removing the resin film 8 in 02 plasma, it is heat treated at high temperature to diffuse impurities in the polycrystalline silicon film 7 and form an emitter region 9. do.

Thereafter, an aluminum film or a gold film is formed on the entire surface and then patterned to form the emitter bridge 10 and base electrode 11 shown in FIG. 1, thereby completing a bipolar transistor.

Note that epitaxially grown single crystal silicon or amorphous silicon may be used instead of polycrystalline silicon constituting the lower emitter electrode. These are St.
- It can be easily changed by changing the MBH growth temperature, growth vacuum degree, etc.

Further, the impurity added to the emitter lower layer electrode may be implanted after forming the emitter lower layer electrode film by ion implantation or thermal diffusion.

[Effects of the Invention] As explained above, the present invention selectively grows silicon only in the opening for the emitter contact and adds impurities to form the emitter lower layer electrode. A desired emitter lower layer electrode can be formed with good reproducibility by being suitably formed within the emitter contact opening, and a bipolar transistor with excellent characteristics can be manufactured.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a bipolar transistor formed by the manufacturing method of the present invention, FIGS. 2(a) to (e) are vertical cross-sectional views showing an embodiment of the present invention in the order of manufacturing steps, and FIG. ) to (d) are vertical cross-sectional views showing the conventional manufacturing method in the order of steps, and FIG. 4 is a vertical cross-sectional view in the middle of the process for explaining problems in the conventional method. l...Silicon substrate, 2...Base region, 3...
First insulating film, 4... Second insulating film, 5.6... Resin film, 7... Polycrystalline silicon film (emitter lower layer electrode), 8
... Resin film, 9... Emitter region, 10... Emitter electrode, 11... Base electrode, 12... Polycrystalline silicon film, 13.14... Resin film. Figure ■ Figure 3

Claims (1)

[Claims] 1. First and second semiconductor substrates are formed on a semiconductor substrate on which a base region is formed.
etching the second insulating film at locations corresponding to the emitter contact and the base contact to form openings; and etching the first insulating film at the emitter contact location to form the semiconductor layer. forming an opening that exposes the surface of the substrate; selectively growing silicon containing impurities in the opening of the emitter contact to form a lower emitter electrode; and forming a first insulator at the base contact location. The method includes the steps of etching a film, diffusing impurities from the emitter lower layer electrode to form an emitter region, and forming an emitter electrode and a base electrode on the emitter contact and base contact, respectively. A method for manufacturing a semiconductor device. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the emitter lower layer electrode is formed by growing impurity-free silicon and then implanting impurities into the silicon by ion implantation or thermal diffusion.