JPS636874A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To decrease transition regions, by performing a patterning process of a groove so that side walls of the groove in an oxidizing film extend to the same plane bearings as a substrate. CONSTITUTION:In a SiO2 film 14 formed on a (100) silicon substrate, a groove 23 is formed to expose the surface of the substrate by epitaxial growth. In this case, the plane bearing of the facet is made to be (10), and the groove 23 is formed in the direction vertical to the facet. Because the side walls 14a of the film 14 are of (100) bearings, singlecrystal silicon and polysilicon are made to grow respectively inside the groove 23 and on a silicon nitride film 21 by normal-pressure epitaxial growth using SiH4+H2. Therefore, generation of transition regions can be remarkably suppressed, together with miniaturization and high-speed performance in a bipolar transistor becoming available.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] This is a method of reducing the transition region in epitaxial polysilicon simultaneous growth by defining the plane orientation of the growth substrate.

[Industrial application field]

The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of reducing a transition region in simultaneous growth of epitaxial polysilicon during the manufacture of a vertical bipolar transistor.

[Conventional technology]

In conventional bipolar transistors, the base is too wide relative to the emitter and the base, which creates parasitic capacitance and reduces the operating speed of the transistor.To solve this problem, the emitter and base are A high-speed bipolar transistor arranged in the vertical direction was developed as shown in the figure. In the figure, 11 is a silicon substrate, 12 is an n+ type buried layer, 13 is an n- epitaxial layer, 14 is a 5i02 film, and 15 is a single crystal silicon. 16 is a polysilicon film, 17 is an emitter, and 18 is a 5iOz film. When a window is made in the SiO2 film 14 to expose the surface of the epitaxial layer 13 and epitaxial growth is performed at normal pressure using a reaction gas of 5iHI+)+2, single crystal silicon grows on the epitaxial layer 13, forming an epitaxial layer. On the other hand, a polysilicon film 16 is grown on the 5i02 film 14 (epitaxial polysilicon simultaneous growth). By using this single crystal silicon layer 15 as a base and forming an n+ type emitter 17 thereon, there is an advantage that the width of the base is considerably smaller than that of a conventional base. The base electrode is drawn out by a p-type doped polysilicon layer 16, and 19 in the figure is a collector contact layer. In addition, B.

E and C are a base electrode, an emitter/vine electrode, and a collector electrode.

According to the inventor's experiments regarding the growth of polysilicon on the 5i02 film 14, as shown in FIG. It grows with unevenness.

In the figure, 20 is a (100) silicon substrate. However, the silicon nitride film (Si3N4
It was confirmed that when the film 21 was grown, polysilicon was easily deposited on the silicon nitride film as shown in FIG. Therefore, in simultaneous growth of epitaxial polysilicon, a silicon nitride film is formed in advance on the SiO2 film on which polysilicon is to be grown.

[Problem that the invention seeks to solve]

The above-mentioned epitaxial and polysilicon simultaneous growth was performed in the sixth step.
To explain with reference to the figure, (100) silicon substrate 20
Epitaxial layer 15 and polysilicon film 1 formed on top
It was confirmed that a portion with crystal defects, that is, a transition region 22, was formed between the two regions.

This portion cannot be used due to crystal defects, and the emitter 17 becomes narrower by the width thereof, which poses a problem of hindering miniaturization of the device.

The present invention was created in view of these points, and it is an object of the present invention to provide a method for reducing the transition region in simultaneous epitaxial polysilicon growth.

[Means for solving problems]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, in which (a) shows an intermediate process of epitaxial and polysilicon simultaneous growth, and (b) shows an intermediate process of epitaxial polysilicon simultaneous growth.
) shows the structure after simultaneous growth.

In the present invention, in the patterning for forming the groove 23 that exposes the substrate surface in the 5i02 film formed on the (100) silicon substrate 20, the surface orientation of the side wall 14a is the same as the surface orientation of the substrate <(100). Set it so that

[Effect]

The present inventor has experimentally found that the occurrence of the transition region described above is also caused by the facets of the epitaxial layer. Referring to the cross-sectional view of a conventional example shown in FIG. Time 5iOz film 1
When the side wall 14a of 4 is parallel to (110), (11
1) It was found that facets of planes or (221) planes appeared.

According to the method of the present invention described above, since patterning is performed so that the 5i02DAO side 914a is in the (100) direction with respect to the (100) substrate, the transition region is significantly reduced.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

According to the method of the present invention, in forming the grooves 23 that expose the substrate surface for epitaxial growth in the SiO+ film 14 formed on the (100) silicon substrate, the surface orientation of the facets as shown in FIG. (100)
Then, grooves 23 are formed in the facets in the vertical direction.

Or, as shown in FIG. 2 (bl), when the facets of the (100) silicon substrate 20 are in the (110) direction, as is the case with general wafers, the angle is extended by 45 degrees with respect to the facets. to form the groove 23. To do so,
It is preferable to tilt the mask for forming the groove 23 by 45 degrees relative to the case of fat in FIG.

When the groove 23 is formed in this way, the side wall 14a of the 5i02 crotch 14 shown in FIG. Single-crystal silicon grows on the silicon nitride film, and polysilicon grows on the silicon nitride film. Figure 1 fat shows the state in the middle of epitaxial growth, and when the growth is completed and the epitaxial layer is 5.
When formed to a thickness of 1,000 mm, the structure shown in FIG. 1 fbl was obtained, with almost no transition region observed. Note that in FIG.
The state in which 5i021i18 is formed by oxidizing the surface of is shown. Since the polysilicon film 16 is used as a base electrode extension part, it is doped to be p-type. After simultaneous growth of epitaxial polysilicon in this manner, the bipolar transistor shown in FIG. 3 is formed.

〔Effect of the invention〕

As described above, the present invention significantly suppresses the generation of transition regions, which has been a problem in the past, in simultaneous epitaxial polysilicon growth, and is effective in miniaturizing and increasing the speed of bipolar transistors.

[Brief explanation of drawings]

Figures 1 (al and b) are sectional views of embodiments of the present invention, Figure 2 (
3 is a cross-sectional view of a high-speed bipolar transistor, FIG. 4 is a cross-sectional view showing problems in the conventional example, and FIG. 5 is a cross-sectional view of an improved example of the conventional example. FIG. 6 is a sectional view of a conventional example, and FIG. 7 is a sectional view of a conventional example. 1 to 7, 11 is a silicon substrate, 12 is a buried layer, 13 is an epitaxial layer, 14 is a 5i02 film, 15 is an epitaxial layer, 16 is a polysilicon film, 17 is an emitter, 18 is a SiO2 film, 19 is a collector contact layer, 20 is a (100) silicon substrate, 21 is a silicon nitride layer, and 23 is a groove. ν! (Y')
- Transistors appear on the island of Hei, the land of life, number 3. The narrow example of the land is on the left, and Figure 4 is the improvement of the heaven side. Column #ri Shiro] Figure 36 Ling Hao Example Rainbow i Country Figure 7

Claims (1)

[Claims] Patterning a groove (23) exposing the substrate surface in an oxide film (14) formed on a semiconductor substrate (20), growing epitaxially in the groove and simultaneously growing polysilicon on the oxide film (14). In the method, an oxide film (14)
A method of manufacturing a semiconductor device, comprising patterning a groove (23) so that a side wall (14a) facing the groove extends in the same plane direction as a substrate.