JPH01214116A - Method of filling in contact hole - Google Patents

Abstract

PURPOSE:To obtain a low resistance contact by forming a semiconductor film on the bottom of a contact hole when metal is buried in the hole, and burying a metal film thereon. CONSTITUTION:A diffused layer 5 of a predetermined shape is formed on an Si substrate 1, the whole surface including it is covered with an SiO2 film 2, a contact hole 3 is opened corresponding to the diffused region 5, and the following is executed when metal is buried in the hole. The bottom of the hole 3 is covered with a Ge film 4 approx. 800Angstrom thick by a thermal chemical growing method with mixture gas of GeH4 and H2 at 1:10 of partial pressure ratio. Thereafter, a W film 6 is buried thereon by a thermal chemical growing method with WF6 and H2 thereby to obtain a dense film. In this case, the growing conditions include 500 deg.C of substrate temperature, 0.1Torr of whole pressure, 2X10<-4>Torr of WF6 partial pressure, 10min of growing time, and it is deposited approx. 8000Angstrom . Thus, it can prevent the layer 5 from corroding, and a leakage current characteristic between the diffused layer and the substrate can be improved.

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 selectively filling contact holes.

[Conventional technology]

When making ohmic contact with an extremely shallow diffusion layer provided in a semiconductor substrate, there is a technique for selectively filling contact holes as a method for preventing alloy spikes.

Conventionally, selective filling of contact holes involves selective growth of tungsten (W) by thermal chemical vapor deposition.

Selective epitaxial growth of silicon (Si) is used.

[Problem to be solved by the invention]

The conventional embedding method described above has the following drawbacks.

1. In case of selective growth of W by thermochemical vapor deposition method.

The initial precipitation of tungsten (W) occurs through reaction with the substrate St, and this chemical reaction is expressed as follows.

This results in erosion of the diffusion layer, which adversely affects the electrical properties of the junction.

2', In the case of selective epitaxial growth of Si.

Since the process temperature is high (≧950° C.), it is unsuitable for semiconductor devices that require a shallow diffusion layer. Furthermore, the specific resistance of the formed film is higher than that of metal, and the contact resistance cannot be lowered sufficiently.

[Means to solve the problem]

The contact burying method of the present invention includes a step of selectively forming a semiconductor film at the bottom of a contact hole, and a step of selectively forming a metal film on the semiconductor ridge.

[Effect]

First, by selectively forming a semiconductor film of about 1,000 nanometers at the bottom of the contact hole in a short time and using this semiconductor film as a buffer to form a metal film, it is possible to prevent the metal film material from penetrating into the diffusion layer. , it is possible to provide a selective embedding method that can realize highly reliable and low resistance contacts.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are cross-sectional views of a semiconductor device showing a first embodiment of the contact hole filling method of the present invention.

In this embodiment, a contact hole 3 partially formed in an insulating film (Si 02 film) 2 formed on the main surface of a silicon (Si 2 ) substrate 1 is filled by the following steps.

(1) At the bottom of the contact hole 3, that is, on the diffusion layer 5,
A germanium (Ge) film 4 is selectively formed by thermal chemical vapor deposition. This selective formation of Ge requires GeHa and H
The growth conditions are, for example, a substrate temperature of 400° C., a total pressure of 2 Torr, and a total pressure of 2 Torr.
The partial pressure ratio of H, a and h is 1:10. The film formation time was 10 minutes,
About 800 Ge films are selectively deposited on the bottom of the contact hole 3 (FIG. 1(a)).

(2) Next, a tungsten (W) film 6 is deposited on this Ge film by thermal chemical vapor deposition using WFs and H2. In this case, the growth conditions were as follows: substrate temperature 500°C, total pressure 0.2 Torr, WFs partial pressure 2X10-4 Torr.
If the deposition time is 10 minutes, approximately 8,000 W films 6 are deposited and the contact hole 3 is filled (FIG. 1(b)).

The deposition of the W film 6 on the Ge film is performed by the following formula (1) at the initial stage of deposition.
, (2), and (3), and once a dense W film is formed, the reaction of formula (4) proceeds dominantly.

3/2Ge+WFa → W+3/2GeFa ↑
・(1)3Ge+WFe −) W+3Ge
F2-(2)2GeF2-) GeHGeF
4 ↑ −(3) WF6+3H2→W+6HF
↑ ...(4) Using the film forming conditions shown in this example, the Ge film 4 is consumed during the growth of the W film 6, and at the end of the embedding, the W film 6 erodes the diffusion layer 5 very slightly. It will end in this state. Therefore, the diffusion layer 5 is in direct contact with W, achieving sufficiently low resistance ohmic characteristics and good junction leak characteristics.

FIGS. 2(a) and 2(b) are cross-sectional views of a semiconductor device showing a second embodiment of the contact hole filling method of the present invention.

In this embodiment, the thickness of the Ge film 4 provided at the bottom of the contact hole 3 is increased (for example, 1000 Å or more), and the W film 6 is
Even after the formation of the Ge film 4, the Ge film 4 is interposed as a barrier layer. In this case, in order to reduce the contact resistance due to the interposition of the Ge film 4, impurities of the group III or V are introduced into the Ge film by ion implantation before forming the W film 6 (FIG. 2(a)). . After this, the W film 6 is embedded (Fig. 2(b)
). In this example, the W film 6 does not penetrate into the diffusion layer 5 at all, and extremely good junction characteristics can be obtained.

FIGS. 3(a) and 3(b) are cross-sectional views of a semiconductor device showing a third embodiment of the contact hole filling method of the present invention.

In this embodiment, the semiconductor layer provided at the bottom of the contact hole 3 is a silicon (Si) film 7.

That is, as shown in FIG. 3(a), the & film 7 is deposited at the bottom of the contact hole 3. Then, as shown in FIG. This deposition can be caused by e.g.
Using 5LH2C12, H2, HCl as raw material gas,
Total pressure 50 Torr, HCI! 1. QvolX,
5it-12cj! 2 at 0.4 vol. 1% and a wafer temperature of 950° C., approximately 500 selective epitaxial Si films 7 are formed (FIG. 3(a)). next,
A W film 6 is deposited under the same conditions as in the previous example (third
Figure (b)). In this embodiment, the contact hole can be filled with the W film 6 without causing almost any erosion to the diffusion H5.

〔Effect of the invention〕

As explained above, the present invention has the following effects by burying a metal film into a contact hole using a semiconductor film as a barrier layer.

1. Unlike the conventional method of selectively growing a W film directly on the diffusion layer (selective W film formation using chemical vapor deposition), erosion of the diffusion layer can be prevented, so the leakage current characteristics between the diffusion layer and the substrate can be reduced. It can be significantly improved.

2. Unlike the conventional method (selective epitaxial method), which only selectively embeds a semiconductor film into the contact hole, most or all of the contact embedding material is a metal film.
A low resistance contact can be realized.

3. When a Ge film is used as the semiconductor film, the process temperature can be kept low, making it easy to apply to shallow junction devices.

4. Even when 3 films are used as the semiconductor film, since the film formation time is short (within 1 minute), the effect on the diffusion layer is less than that of embedding by the conventional selective 3 epitaxial method.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are cross-sectional views of a semiconductor device showing a first embodiment of the contact hole filling method of the present invention, and FIGS. FIG. 3(a) is a cross-sectional view of a semiconductor device showing a second embodiment of the embedding method.
, (b) is a sectional view of a semiconductor device showing a third embodiment of the contact hole filling method of the present invention. 1...One substrate, 2...8i 02 film 3...
・Contact hole, 4...Ge film, 5...diffusion layer, 6...
W film, 7...Si film. Patent applicant: Japan Electric Co., Ltd., 71st Attorney, Susumu Uchihara (a) (b) Figure 1 (a) (b) Figure 2

Claims (1)

[Claims] 1. A method for burying a contact hole in a semiconductor device, comprising the steps of selectively forming a semiconductor film at the bottom of the contact hole, and selectively forming a metal film on the semiconductor film. A contact hole embedding method characterized by comprising: 2. The contact hole filling method according to claim 1, further comprising the step of introducing group III or group V impurities into the semiconductor film after forming the semiconductor film.