JPH03190245A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To inhibit generation of a crystal defect by forming a stack having the structure of an insulating film-a semiconductor-an insulating film onto the intrinsic base region of the surface of a semiconductor substrate. CONSTITUTION:A stack 23 having the structure of an insulating film 21-a semiconductor 20-an insulating film 19 is formed onto the intrinsic base region 22 of the surface of a semiconductor substrate 15. The intrinsic base region 22 is protected and a base electrode 25 can be formed at that time. When the stack 23 is removed through etching and an emitter leading-out section opening 28 is shaped, the insulating film 19 brought into contact with an epitaxial layer 17 can be removed through wet etching, and large damage and contamination are not induced on an epitaxial surface. Accordingly, the generation of a crystal defect can be inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a semiconductor device in which bipolar transistors are made faster and smaller.

Conventional technology In recent years, bipolar transistors have been miniaturized beyond the limits of photolithography using various self-alignment techniques.
It has achieved extremely high speed and high performance characteristics.

A conventional semiconductor device and its manufacturing method are shown in Figure 2 (
An example of a method for manufacturing an NPN transistor is shown in al~(dl).

First, as shown in FIG. 2 (al), after forming an N-type buried collector layer 2 on the surface of a P-type silicon substrate 1, an N-type epitaxial layer 3 is grown.Next, an element isolation LOCO 3 is formed.
A film 4 is formed on the surface of the N-type epitaxial layer 3. Next, the N-type epitaxial layer 3 and the element isolation LOGO8 film 4
A P+ polysilicon film 5 and a CVD oxide film 6, which will serve as a base lead-out electrode, are grown over the entire surface. Next, the CVD oxide film 6 and then the P+ polysilicon film 5 are removed by etching using a photolithographic resist as a mask to expose the intrinsic base region 7 on the surface of the N-type epitaxial layer 3.

Next, as shown in FIG. 2(b), after growing a nitride film 8 over the entire surface, P-type impurities are introduced into the N-type epitaxial layer 3 from the P+ polysilicon film 5 by heat treatment, and a P-type external base layer is formed. form 9.

Next, as shown in FIG. 2 (C1), the nitride film 8 is anisotropically etched to form a nitride film sidewall 10, a polysilicon base lead electrode 5, and an emitter lead-out hole 11.

Finally, as shown in FIG. 2 (fd), the polysilicon film grown on the entire surface is selectively etched away using a photolithographic resist as a mask to form an emitter electrode 12. P-type impurities are ion-implanted, and P-type is removed from the polysilicon emitter electrode 12 through the emitter lead-out hole 11 by heat treatment.
A type impurity is introduced into the intrinsic base region forming portion 7 to form a P-based base layer 13. Furthermore, N-type impurities are ion-implanted into the polysilicon emitter electrode 12, and N-type impurities are introduced into the intrinsic base layer 13 from the polysilicon emitter electrode 12 through the emitter lead-out hole 11 by heat treatment, thereby forming the N-type emitter layer 14. Form.

According to the method for manufacturing a semiconductor device as described above, the external base region, emitter region, base electrode extension part, and emitter electrode extension part of a bipolar transistor can all be formed in a self-aligned manner, making it possible to dramatically increase the speed and miniaturize the bipolar transistor. You can aim for it.

Problems to be Solved by the Invention In the above-mentioned prior art, when the P+ polysilicon film that becomes the base extraction electrode is selectively etched away to expose the intrinsic base region on the surface of the epitaxial layer, the base of the polysilicon film is silicon. Since it is an epitaxial layer, the etching selectivity is low, which induces large damage and contamination on the surface of the epitaxial layer, causing crystal defects. Crystal defects then cause leakage at each junction, degrading transistor characteristics.

Means for Solving the Problems In order to solve the problems, the method for manufacturing a semiconductor device of the present invention provides an intrinsic base region on the surface of a semiconductor substrate, an extrinsic base region surrounding the intrinsic base region, and a periphery of the extrinsic base region. a step of growing a second insulating film, followed by a first semiconductor film, and then a third insulating film on the entire surface of the formed first insulating film; Then, the second insulating film is selectively etched away to form a stack consisting of the second insulating film, the first semiconductor film, and the third insulating film on the intrinsic base region. a step of forming a sidewall made of a fourth insulating film on the side wall of the stack; a step of growing a second semiconductor film on the entire surface; and a step of growing a second semiconductor film on the stack and the sidewall. The method includes the steps of etching away the semiconductor film to form a base extraction electrode of the second semiconductor film, and etching away the stack to form a hole between the emitter extraction parts.

According to the method for manufacturing a semiconductor device of the present invention, a stack of an insulating film-semiconductor insulating film structure is formed on the intrinsic base region on the surface of the semiconductor substrate, thereby protecting the intrinsic base region and forming a base electrode. Furthermore, when the stack is removed by etching to form a hole in the emitter lead-out portion, the insulating film in contact with the epitaxial layer can be removed by wet etching, without causing major damage or contamination to the epitaxial surface.

Embodiment FIG. 1 (f+) is a cross-sectional view showing an embodiment of the present invention in the order of steps of an NPN transistor.

First, as shown in FIG. 1 (al), a P-type silicon substrate 15
After forming an N-type buried collector layer 16 on the 0 surface, an N-type epitaxial layer 17 that will become a semiconductor substrate is grown.

Next, the element isolation LOcO3 film 18, which becomes the first insulating film, is
After forming the oxide film 19 on the surface of the type epitaxial layer 17, the oxide film 19, which will become the second insulating film, is formed on the entire surface of the element isolation LOCO3 film 18 and the N-type epitaxial layer 17.
After growing a polysilicon film 20 of about 200 to 300 nm, which will become the first semiconductor film, and then growing a nitride film 21 of about 50 to 1100 nm, which will become the third insulating film, a resist is masked by photolithography. First, a nitride film 21, a polysilicon film 20, and an oxide film 1.
9 is selectively etched away to form a nitride film 21 on the intrinsic base region forming portion 22 on the surface of the N-type epitaxial layer 17.
Stack 2 consisting of a polysilicon film 20 and an oxide film 19
form 3.

Next, as shown in FIG. 1 (bl), a nitride film to be a fourth insulating film is grown to a thickness of about 200 to 300 nm over the entire surface, and then anisotropically etched to form a nitride film sidewall 24.

Next, as shown in FIG. 1 (C1), after growing a polysilicon film that will become the second semiconductor film to a thickness of about 400 to 500 nm over the entire surface, a resist is applied to the entire surface. Next, the resist, stack 23, and nitride film side walls are formed. At the same time, the polysilicon film on 24 is removed by etching to flatten the surface, and a polysilicon base lead electrode 25 is formed.

Next, as shown in FIG. After ion-implanting boron as the first impurity of about 5X1015 to IXIO16Cm-2, boron is introduced into the N-type epitaxial layer 17 from the polysilicon base lead-out stain electrode 25 by heat treatment at 1000°C for 30 to 60 minutes. A base layer 27 is formed.

Next, as shown in FIG. 1(e), a nitride film 2 is left on the intrinsic base region forming portion 22 of the surface portion of the N-type epitaxial layer 17 using a photolithography resist as a mask.
1, the polysilicon film 20 is removed by etching, and then the oxide film 19 is removed by wet etching to form an emitter lead-out hole 28.

Finally, as shown in FIG. 1(f), a polysilicon film is grown on the entire surface, and then the polysilicon film is selectively etched away using a photolithography resist as a mask to form an emitter extraction electrode 29. Furthermore, ions of boron as a second impurity are implanted into the polysilicon emitter extraction electrode 29 to the extent of 1 to 5X1014CI+11-2, and through heat treatment at 950°C for about 30 minutes, the polysilicon emitter extraction electrode 29 is passed through the emitter extraction part hole 28.
9, boron is introduced into the intrinsic base region forming portion 22 to form the intrinsic base layer 30. Furthermore, arsenic as a third impurity is added to the polysilicon emitter lead electrode 29 at 1×10
Ions of about 16CI11-2 are implanted, and arsenic is introduced into the intrinsic base layer 30 from the polysilicon emitter extraction electrode 29 through the emitter extraction part hole 28 through a heat treatment at 900 DEG C. for about 30 minutes to form an emitter layer 31.

According to the method for manufacturing a semiconductor device as described above, the nitride film 2
1, a polysilicon film 20, and an oxide film 19, the stack 23 protects the intrinsic base region formation portion 22 on the surface of the N-type epitaxial layer 17 and forms the base extraction electrode 25, thereby preventing large damage to the surface of the N-type epitaxial layer. This can prevent the induction of pollution. Furthermore, when removing the stack 23 by etching to form the emitter lead-out hole 28, the oxide film 19 in contact with the N-type epitaxial layer can be removed by wet etching, which prevents damage to the N-type epitaxial layer in this process. Can be reduced. Therefore, the intrinsic base layer 30 has very few crystal defects and has a junction depth of 0.2 μm or less, and the emitter layer 31 has a junction depth of 0.1 μm or less.
A bipolar transistor with .

Note that in the example, the third insulating film was a nitride film, but
The third insulating film may be an oxide film.

In addition, in the example, the fourth insulating film was a nitride film, but
The fourth insulating film may be an oxide film.

Further, in the embodiment, the surface of the polysilicon-based lead electrode was oxidized to form an insulating film with the emitter lead electrode, but this insulating film may be a CVD insulating film.

As described in detail, according to the method for manufacturing a semiconductor device of the present invention, a stack of an insulating film-semiconductor-insulating film structure is formed on the intrinsic base region on the surface of a semiconductor substrate to protect the intrinsic base region. It is possible to form a base electrode using the same method, thereby preventing large damage or contamination from occurring on the surface of the N-type epitaxial layer, and suppressing the occurrence of crystal defects.

Therefore, the occurrence of leakage at each junction of the bipolar transistor can be suppressed.

[Brief explanation of drawings]

FIG. 1 (al to ffl indicate embodiments of the present invention, NPN
Step-by-step cross-sectional views of bipolar transistors, Figure 2 (al
~(dl is a cross-sectional view of a conventional example in the order of steps. 5...P+ polysilicon film (base extraction electrode), 6...CVD oxide film, 7...Intrinsic Base region, 8...Nitride film, 10...
Nitride film side wall, 11... Emitter lead-out hole, 17... N-type epitaxial layer, 1
8...Element isolation LOGO8 film, 19...
・Oxide film, 20...Polysilicon film, 21...
... Nitride film, 22 ... Intrinsic base region forming part, 23 ... Stack, 24 ... Nitride film side wall, 25 ... Polysilicon Base extraction electrode, 28...Emitter extraction part hole.

Claims (1)

[Claims] A second insulating film is formed over the entire surface of an intrinsic base region on the surface of the semiconductor substrate, an extrinsic base region surrounding the intrinsic base region, and a first insulating film formed around the extrinsic base region, followed by a first semiconductor film. Next, a step of growing a third insulating film, and selectively etching away the third insulating film, then the first semiconductor film, and then the second insulating film on the intrinsic base region. forming a stack including the second insulating film, the first semiconductor film, and the third insulating film; and forming a sidewall including a fourth insulating film on a sidewall of the stack. , second on the entire surface
a step of etching away the second semiconductor film on the stack and the sidewalls to form a base extraction electrode of the second semiconductor film; and etching away the stack. 1. A method of manufacturing a semiconductor device, comprising the step of: forming a hole between emitter lead-out portions.