JPH0462918A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To turn the whole polysilicon Si film, which is grown in a contact hole, into a polycrystal line one and to prevent a protrusion, which is a local single crystal Si film, from being grown by a wherein in a process for forming the polysilicon film in the hole, a contact part is uniformly covered with an insulating film. CONSTITUTION:An SiO2 film which is used as a first insulating film 2 is applied on an Si substrate 1 by a thermal oxidation method and a contact hole 3 is opened by a lithography technique. Then, a very thin SiO2 film is formed in the hole 3 as a second insulating film 4. Subsequently, a polysilicon film 5 is grown on the substrate 1 by a vacuum CVD method. Even if there is the very thin SiO2 film 4 in the hole 3, the film 4 is instantaneously broken by a high--temperature heat treatment at the time of an emitter diffusion in the latter process and an adverse effect is not inflicted by the film 4 on a contact resistance between the substrate 1 and an electrode consisting of the film 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to the growth of a polycrystalline silicon (polySt) film when having contact with a silicon (Si) substrate.

Or regarding the treatment of the substrate surface prior to this growth.

The purpose is to solve the problem of abnormal growth of monocrystalline Si protrusions on the surface of the poly-Si film during the poly-Si film formation process, resulting in non-uniformity of the poly-Si film, and to ensure the uniformity of the poly-St film surface. year.

A step of coating a first insulating film on a Si substrate, forming a contact hole exposing the Si substrate in the first insulating film, and forming a second insulating film having a first thickness on the surface of the contact hole. and a step of forming an insulating film.

The method is configured to include a step of covering the Si substrate with a poly-Si film, and a step of performing heat treatment to such an extent that the second insulating film is destroyed.

[Industrial application field]

The present invention relates to the growth of a poly-Si film when it has contact with a Si substrate, or to the treatment of the surface of a Si substrate prior to this growth.

In recent years, devices with a Bi-CMO5 structure have been occupying a large position in Si semiconductors due to their high speed and low power consumption.

In devices with this old-CMO3 structure, in many cases it is required that the poly-Si film functioning as a gate and the Si substrate be in direct contact.

The present invention provides a technique that enables microscopically uniform growth of this poly-Si film.

[Conventional technology]

FIG. 3 is an explanatory diagram of a conventional example.

In the figure, 6 is a Si substrate, 7 is a 5in2 film, 8 is a contact hole, 9 is a poly-Si film, and 10 is a single crystal Si protrusion.

In the growth of a poly-Si film in the case of contact with the Si substrate of a conventional Bi-CMO3 structure device, as shown in FIG. 3(a), after forming a contact hole 8, hydrofluoric acid (IIP) treatment is performed. After exposing the surface of the Si substrate 6 at about 620° C., as shown in the second half (b), the poly-Si substrate 6 is contacted with 1-hole 8''2 and +S.
It had grown on the iO□ film 7.

However, in this method, when growing the poly-Si film 9 on the surface of the sj group vii, 6, monocrystalline Si protrusions 10 grow abnormally on the surface of the Si substrate 6 during the growth process, and the poly-Si film 9 The surface was uneven.

[Problem to be solved by the invention]

Therefore, when patterning a poly-Si film that has become non-uniform, the single crystal St causes patterning defects. In addition, the protrusions of the abnormally grown single crystal Si are broken, causing problems such as an increase in foreign matter such as particles and a decrease in product yield.

Regarding the cause of the above-mentioned abnormal growth, in the area where the Si substrate inside the contact hole is exposed by hydrofluoric acid, the surface of the Si substrate in the contact hole is microscopically visible due to particles and minute SiO□ film residues, etc. This is thought to be due to the presence of other parts.

Therefore, non-uniform nucleation occurs during the growth of the poly-Si film, leading to the above-mentioned protrusions.

In view of two or more points, the present invention solves the problem of abnormal growth of monocrystalline Si protrusions on the surface of a poly-Si film in the poly-Si film formation process, making the poly-Si film non-uniform.
The purpose is to ensure uniformity of the film surface.

[Means to solve the problem]

FIG. 1 is a principle explanatory diagram of the present invention and a schematic cross-sectional view in order of steps of an embodiment.

In the figure, I is a Si substrate, 2 is a first insulating film 3 is a contact hole, 4 is a second insulating film, and 5 is a poly-Si film.

In the present invention, by forming an extremely thin insulating film (5 to 50 layers) such as a 5iO7 film in the contact hole before growing the poly-Si film, the uneven nucleation described above is prevented and the uniform poly-Si film is formed. It grows a film.

Due to the presence of this insulating film inside the contact ball, there is a concern that the contact resistance between the poly-Si film and the Si substrate will increase, but in reality, the high temperature heat treatment during emitter diffusion in the post-process step 5 causes the contact resistance to increase. The extremely thin insulating film is destroyed and the contact resistance is not adversely affected.

The object of the present invention is as shown in FIG. 1(a).

A step of coating a first insulating film 2 on the Si substrate l and forming a contact hole 3 exposing the Si substrate 1 in the first insulating film 2.

As shown in FIG. 1(b), a second layer is formed on the surface of the contact hole 3 to have a first thickness of 50 Å or less.
a step of forming an insulating film 4;

As shown in FIG. 1(C), poly-Si is deposited on the Si substrate l.
and a step of coating the membrane 5.

This is achieved by subsequently performing heat treatment at a temperature that destroys the second insulating film 4.

[Effect]

In the present invention, as shown in FIG.
In the process of forming the i-film, the contact area is uniformly covered with an insulating film, so all the poly-Si film that grows inside the contact hole becomes polycrystalline Si, resulting in the formation of local single-crystal S] protrusions. It becomes possible to prevent growth.

Therefore, it is possible to prevent defective patterning of the poly-Si film.

〔Example〕

FIG. 1 is a schematic cross-sectional view of an embodiment of the present invention in the order of steps.

FIG. 2 shows the relationship between the thickness of the SiO□ film formed and the nitric acid treatment time.

As shown in FIG. 1(a), a 5iOz film as a first insulating film 2 is coated on a Si substrate 1 to a thickness of 4,000 yen by thermal oxidation. Then, a contact hole 3 for making contact with the Si substrate 1 is opened using lithography technology.

Next, as shown in FIG. 1(b), the Si substrate 1 is
Treat with nitric acid (HNO3) heated to °C for 10 min.

Next, wash with pure water for 10 minutes and dry naturally for 10 minutes.

Inside the contact ball 3, as a second insulating film 4.

An extremely thin SiO□ film with a thickness of 20 people is formed.

The formation of such an extremely thin SiO□ film 4 is shown in FIG. As can be seen from the relationship diagram between the thickness of the SiO□ film formed and the treatment time with nitric acid at 80°C, it is possible to increase the
An ultra-thin 5i (h film 4) of any thickness can be formed on the Si substrate 1.

Subsequently, as shown in FIG. 1(C), the Si substrate 1 was heated to 620°C + 0.2 Torr by low pressure CVD method.
Introduce silane (SiH4) gas for 80 seconds and
Process for minutes.

A poly-Si film 5 is grown to a thickness of 4,000 nm.

Even if the ultra-thin 5i02 film 4 is present in the contact hole 3, the contact electrode layer of the poly-Si film 5 grown thereon will have an angle of 1,000° during emitter diffusion in the later process.
The thin SiO□ film 4 is instantaneously destroyed by heat treatment at a high temperature of 1,050°C or higher (for example, 1,050°C for 30 seconds), and the contact resistance between the Si substrate 1 and the electrode of the poly-Si film 5 is reduced. has no adverse effect.

Therefore, even if the extremely thin insulating film of the present invention is formed.

The contact resistance between the Si substrate and the poly-Si film was exactly the same as that in the conventional process.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent the formation of protrusions of single crystal Si in the poly-Si film formed in the contact hole, and it is possible to form a uniform poly-Si film in the contact hole. I can do it.

This greatly contributes to improving reliability.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of the present invention in the order of steps. FIG. 2 is a diagram showing the relationship between the thickness of the SiO□ film formed and the nitric acid treatment time. FIG. 3 is an explanatory diagram of a conventional example. In fig. 1 is a Si substrate, and 2 is a first insulating film 3 that is a contact hole.

Claims (1)

[Claims] A silicon substrate (1) is covered with a first insulating film (2), and a contact hole (3) is formed in the first insulating film (2) to expose the silicon substrate (1). forming a second insulating film (4) having a first thickness on the surface of the contact hole (3); and a step of forming a second insulating film (4) having a first thickness on the surface of the contact hole (3);
A method for manufacturing a semiconductor device, comprising the steps of: coating a polycrystalline silicon film (5) thereon; and performing heat treatment to such an extent that the second insulating film (4) is destroyed.