JPH02297935A - Semiconductor device - Google Patents

Abstract

PURPOSE:To realize the margin free of an etching back step by burying a contact hole among the three layers of a tungsten silicide film, a silicon oxide film, and a polycrystalline Si film, and holding the polycrystalline silicon film in the hole in a nondoped state. CONSTITUTION:A tungsten silicide film 5 is deposited on a whole Si substrate by a sputtering method, and a silicon oxide film 6 is grown by a CVD method. Then, when a polycrystalline silicon film 7 is grown on the whole substrate surface by a CVD method, a contact hole 3 is buried with the film 7, and the film 7 above the hole becomes substantially flat. Then, phosphorus is diffused by thermal phosphorus diffusing. Then, the film 7 is etched back with etchant having selection ratio of a phosphorusdoped polycrystalline silicon film and a nondoped polycrystalline silicon film. In this case, the film 6 and the polysilicon 7 buried in the hole 3 become stoppers for the etchback, becoming process margin free of the etchback.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and more particularly to a semiconductor device having a contact structure and wiring structure embedded with an improved polycrystalline silicon film.

[Conventional technology]

Conventionally, contact holes have been filled with a polycrystalline silicon film in a structure formed of a single layer or multiple layers of polycrystalline silicon films.

[Problem to be solved by the invention]

In the conventional buried contact using a polycrystalline silicon film as described above, a single or multilayer polycrystalline silicon film is grown on the surface of a semiconductor substrate including a contact hole, and then etched back to form a polycrystalline silicon film only inside the contact hole. A manufacturing method is used in which the silicon film remains. At this time, phosphorus is introduced into the polycrystalline silicon film to reduce contact resistance. Therefore, there is no film that acts as an etch-back stopper, and it is difficult to stably fill contact holes due to variations in polycrystalline silicon film thickness and etch-back rate, which impedes mass production. There is a drawback.

[Means to solve the problem]

The semiconductor device of the present invention includes a single crystal or polycrystalline semiconductor layer formed on a semiconductor substrate, a wiring metal layer formed on the semiconductor layer with an insulating film interposed therebetween, and a wiring between the semiconductor layer and the wiring. A semiconductor device having a contact hole for forming an electrical connection between metal layers, the contact hole includes a high melting point metal silicide film provided extending over the insulating film, and a contact hole for forming an electrical connection between the metal layers. embedded with a three-layer film consisting of a silicon-based insulating film provided only on the surface of the refractory metal silicide film inside and a polycrystalline silicon film provided only inside the contact hole; , the extending portions of the refractory metal silicide film on the insulating film are formed in the same pattern.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of one embodiment of the present invention.

In this embodiment, contact between an N-type source/drain and an aluminum wiring will be explained.

This embodiment includes an N-type source/drain 2 on a P-type nested crystal silicon substrate 1, an interlayer insulating film 4 provided with a contact hole 3 on the substrate, and an interlayer insulating film 4 inside the contact hole 3. The tungsten silicide film 5 extended above, the silicon oxide film 6 deposited on the surface of the tungsten silicide film 5 inside the contact hole 3, and the contact hole 3
It consists of a polycrystalline silicon film 7 embedded therein and an aluminum wiring 8 formed in the same pattern as the tungsten silicide film 5.

Next, an embodiment of a desirable manufacturing method for achieving the above-described structure of the invention will be described with reference to FIGS. 3 to 6.

Figure 3 shows that in the manufacturing process of a semiconductor device, an N-type source/drain 2 and an interlayer insulating film 4 are deposited, and a 1 μm square contact hole 3 is opened to connect the N-type source/drain 2 and aluminum wiring. It represents the point at which the hole was made. The manufacturing up to this point is not related to the gist of the present invention, so the description thereof will be omitted.

Next, as shown in FIG. 4, a tungsten silicide film 5 with a thickness of 200% is deposited on the entire surface of the silicon substrate by sputtering.
It is deposited at a thickness of about 0 people. Next, about 500 silicon oxide films 6 are grown using the usual CVD method. Next, a polycrystalline silicon film 7 is grown to a thickness of about 1 μm on the entire surface of the silicon substrate by the usual CVD method.
The 1 μm square contact hole 3 is filled with a polycrystalline silicon film 7, and the polycrystalline silicon film 7 above the contact hole becomes substantially flat. Subsequently, phosphorus is diffused into the polycrystalline silicon film 7 by thermal phosphorus diffusion. By selecting appropriate conditions, this phosphorus diffusion takes advantage of the difference in thickness between the polycrystalline silicon film embedded in the contact hole 3 and the polycrystalline silicon film in other parts. It is possible to make only the buried polycrystalline silicon film 7 hardly diffused.

Next, as shown in FIG. 5, the polycrystalline silicon film 7 is etched back with an etching solution having a selectivity between the phosphorus-doped polycrystalline silicon film and the non-doped polycrystalline silicon film. At this time, the silicon oxide film 6 and the non-doped polycrystalline silicon 7 buried in the contact hole 3 serve as an etch-back stopper, and the etch-back process margin becomes free.

Next, as shown in FIG. 6, the silicon oxide film 6 remaining on the silicon substrate surface is removed, an aluminum film 8 is deposited as a wiring metal by sputtering, and the desired shape is formed by ordinary phosphorography technology. Aluminum film 8 and tungsten silicide film 5 extending over the interlayer insulating film
Figure 1 is obtained by sequentially etching the images.

It is clear from the gist of the invention that the embodiments described above are merely examples of the present invention. For example, the present invention is not limited to the conductivity type and can be implemented not only in contact with a source/drain but also in contact with a polysilicon wiring, a contact with a silicide wiring, and the like. Furthermore, the materials and manufacturing methods used in the examples are not specified; for example, instead of a silicon oxide film, a silicon nitride film,
It is also possible to use titanium silicide instead of tungsten silicide. In addition, phosphorus can be introduced into the polycrystalline silicon film by ion implantation.
A similar effect can be obtained even if the polycrystalline silicon film is etched back by anisotropic dry etching.

〔Effect of the invention〕

As explained above, the present invention has a structure in which the contact hole is filled between three layers: a tungsten silicide film, a silicon oxide film, and a polycrystalline silicon film, and the polycrystalline silicon film inside the contact hole is kept in a non-doped state. There is. This allows the silicon oxide film and the non-doped polycrystalline silicon film in the contact hole to be used as an etch-back stopper, making it possible to achieve a margin-free etch-back process.

Further, contact resistance can be reduced by making contact with the underlying wiring layer using tungsten silicide.

Furthermore, the wiring section has a two-layer structure of tungsten silicide and aluminum, making it resistant to electromigration.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a sectional view of a conventional semiconductor device, and Figs. 3 to 6 are shown in order of steps to explain an embodiment of the invention. FIG. 1.11...P-type nest crystal silicon substrate, 2,2
1...Nu source/drain, 3.31...
... Contact hole, 4, 41 ... Interlayer insulating film, 5 ... Tungsten silicide film, 6 ...
... Silicon oxide film, 7.71 ... Polycrystalline silicon film, 8,81 ... Aluminum film.

Claims (1)

[Claims] A single crystal or polycrystalline semiconductor layer formed on a semiconductor substrate, a wiring metal layer formed on top of the semiconductor layer with an insulating film interposed therebetween, and an electrical connection between the semiconductor layer and the wiring metal layer. In the semiconductor device, the contact hole includes a high melting point metal silicide film extending over the insulating film, and the high melting point metal silicide inside the contact hole. embedded with a three-layer film of a silicon-based insulating film provided only on the film surface and a polycrystalline silicon film provided only inside the contact hole, and the wiring metal layer and the high melting point metal silicide film. A semiconductor device characterized in that the extending portions on the insulating film are formed in the same pattern.