JPH01228169A - Semiconductor device - Google Patents

Abstract

PURPOSE:To easily break insulation presented by a spontaneous oxide film and thereby to improve device reliability by a method wherein a polycrystalline silicon layer is provided in contact with a silicon substrate or polycrystalline silicon substrate through the intermediary of a metal layer or metal silicide layer. CONSTITUTION:A metal layer or metal silicide layer 4 is formed in contact with a silicon substrate 1 in a contact hole 3, and a polycrystalline silicon layer 6 is formed in contact with the metal layer or metal silicide layer 4 in a contact hole 3 and on an insulating layer 2. The natural oxide film is reduced using a raw material gas of the metal layer 4 or a reaction product, or reaction is caused in a heat treatment to take place between the metal layer 4 or silicon nearby and the spontaneous oxide film, which destroys the spontaneous oxide film for the realization of excellent electrical juction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to a wiring structure having contact holes.

[Conventional technology]

FIG. 2 is a cross-sectional view showing the manufacturing process of a conventional semiconductor device. As shown in FIG. 2, a silicon (Si) substrate (1) is
After forming an insulating layer (2) such as a silicon oxide film on the main surface of the substrate by thermal oxidation, CVD, sputtering, etc., as shown in FIG. Contact holes (
3) Form. At this time, a natural oxide film (7) is formed on the surface of the silicon substrate (1) within the contact hole (3). Subsequently, an impurity layer (5) is formed near the surface of the silicon substrate (1) through the natural oxide film (7) in the contact hole (3) using ion implantation, thermal diffusion, or the like. Next, as shown in FIG. 2 (q), the impurity M (5) near the surface of the silicon substrate (1) is contacted in the contact hole (3), and the impurity is formed on the contact hole (3) and the insulating layer (2). , a polycrystalline silicon layer (6) is formed by the CVD method, and buttered by photolithography, etching, etc. When using phosphorus, which forms a deep diffusion layer, which has been conventionally used as an impurity for the impurity layer (5), The polycrystalline silicon film (6) and the impurity layer (5) are connected to the contact hole (
3) through a natural oxide film (7). In this case, the natural oxide film (7) will act as a resistor.

[Problem to be solved by the invention]

In the conventional semiconductor device as described above, the silicon substrate (1) has a contact hole (3) as shown in FIG.
A natural oxide film (7) is formed by contacting air through the film. This natural oxide film (7) exists even after the formation of the polycrystalline silicon layer (6) as shown in FIG. 5) acts as a resistor on the surface that is in contact with it, has a large resistance value, and when mass-produced, there is a large variation in resistance value between devices.

Particularly, when a large-diameter wafer is inserted into a CVD furnace, a large amount of oxygen enters the air and is not sufficiently replaced with nitrogen gas, so that the natural oxide film (7) tends to become thick. Furthermore, when inserting into a CVD furnace at high temperature to shorten process time, the natural oxide film (7) tends to become thicker.

Further, when arsenic, which forms a shallow diffusion layer, is used as an impurity in the impurity layer (5), the resistance value of the natural oxide film (7) becomes particularly high. Furthermore, as semiconductor devices become more dense and the size of the contact hole (3) becomes smaller, the natural oxide film (7
) comes to cover the entire surface in contact with the impurity layer (5) within the contact hole (3) and is electrically insulated.

The present invention was made to solve these problems, and an object of the present invention is to obtain a semiconductor device having excellent electrical connections.

[Means to solve the problem]

In the semiconductor device according to the present invention, in the contact hole,
By forming a metal layer or metal silicide layer in contact with a silicon substrate and disposing a polycrystalline silicon layer in contact with the metal layer or metal silicide layer over the contact hole and the insulating layer, a natural oxide film that is an insulator can be formed. It is made to have excellent electrical bonding.

[Effect]

In this invention, a metal layer in contact with the silicon substrate is formed in the contact hole by a CVD method or the like, and the natural oxide film is reduced with the raw material gas or reaction product, or the metal layer and the natural oxide film or the surrounding area are removed by heat treatment. The natural oxide film can be destroyed by causing a reaction with silicon.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the manufacturing process of the semiconductor device according to the above embodiment, and FIG.
is in the same state as As shown in FIG. 1 (c), contact holes (3) are formed by selective patterning using photolithography and etching, and then near the surface of the silicon substrate (1) by thermal diffusion, ion implantation, etc. After forming an impurity layer (5) on the silicon substrate (5), a metal layer such as tungsten (W) or a metal silicide layer (4) is selectively deposited on the silicon substrate (4) in the contact hole by a CVD method containing a metal halide as a raw material gas. 1) Grow thinly on the surface in contact with. Next, as shown in FIG. 1(q), polycrystalline silicon 7m (6) is formed by CVD and patterned by photolithography, etching, and the like.

In the semiconductor device configured as described above, CVD
For example, a metal layer is formed by the reaction of WF6+(Sl-+W+SiF4↑ or WF6+3H,→W+6HF).When Si reacts with W and replaces W, the volume becomes about half and the natural oxide film is torn apart. The natural oxide film is removed by the reaction with HF, which is a reaction product.Furthermore, by heat treatment, W is heated to 650°C.
reacts with Si to form WSi.

By causing a reaction between the metal layer and the natural oxide film or the silicon in the vicinity, the natural oxide film is destroyed, resulting in excellent electrical bonding.

In addition, in the metal layer or the metal silicide layer (4) in FIG.
) After formation, the impurity layer (5) may be formed by ion implantation, or after the metal layer is formed, heat treatment may be performed to turn it into silicide.

Alternatively, the polycrystalline silicon layer (6) shown in FIG.
After forming, the metal j- may be silicified by heat treatment.

Further, the present invention can be applied not only to a contact between a silicon substrate and a polycrystalline silicon layer, but also to a contact between a polycrystalline silicon substrate and a polycrystalline silicon layer, and the polycrystalline silicon may be amorphous silicon.

〔Effect of the invention〕

As explained above, this invention provides a polycrystalline silicon layer in contact with a silicon substrate or a polycrystalline silicon substrate via a metal layer or a metal silicide layer, so that the insulation caused by the natural oxide film can be easily destroyed, and the reliability can be improved. A high quality semiconductor device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the manufacturing process of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing the manufacturing process of a conventional semiconductor device. In the figure, (1) is a silicon substrate or polycrystalline silicon substrate, (2) is an insulating layer, (3) is a contact hole,
(4) is a metal l- or metal silicide layer, (5) is an impurity layer, (6) is a polycrystalline silicon layer, and (7) is a natural oxide film. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwa Figure 1

Claims (1)

[Claims] A silicon substrate or a polycrystalline silicon substrate, an insulating layer provided on this substrate and having a contact hole reaching the substrate, a metal layer or metal silicide layer provided in contact with the substrate within the contact hole, and this metal. A semiconductor device comprising a polycrystalline silicon layer in contact with a metal silicide layer or a metal silicide layer and provided on the contact hole and the insulating layer.