JPH02296335A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve operation speed and yield by arranging a second wiring laminated on a first wiring via an insulating film, and bringing the second wiring into contact with a polycrystalline silicon film of the first wiring through a connection hole formed on the insulating film. CONSTITUTION:On the surface of a semiconductor substrate 15, an insulating film 16 turning to a gate oxide film and the like is formed, and thereon a first wiring 11, an insulating film 13, and a second wiring 12 are laminated, thereby constituting a multilayer wiring structure, in which the first and the second wirings are mutually connected by a connection hole 14 formed in the insulating film 13. The second wiring 12 is brought into contact with a polycrystalline silicon film 11a hard to be oxidized, cut of the polycrystalline silicon film 11a and a metal film 11b which constitute the first wiring 11. Hence an oxide insulating film is not formed between the first wiring and the second wiring, so that the contact resistance between them can be remarkably reduced. Thereby the operating speed of a semiconductor device is improved, wirings are surely connected, and the yield is remarkably improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention has a so-called multilayer wiring structure, in which a polycrystalline silicon film and a metal film made of a high melting point metal or a high melting point metal silicide are laminated as electrode wiring. The present invention relates to a semiconductor device using wiring having a two-layer structure.

[Conventional technology]

Conventionally, for example, polycrystalline silicon films have been widely used as gate electrode materials in MO3 type transistors, but recently, polycrystalline silicon films and high-melting point metal films or high-melting point metal silica I films have been laminated. Electrode wiring having a two-layer structure has come to be used. Such a two-layer structure electrode wiring is stable and stable due to the stability of the interface with the GaI/oxide film of the polycrystalline solicon and the low resistance of the high melting point metal or high melting point silicide. A semiconductor device capable of high-speed circuit operation can be realized.

FIG. 3 shows a partial structure of a semiconductor device using the above-described two-layer structure of electrode wiring.

This semiconductor device has a so-called multilayer wiring structure in which a first wiring 1 and a second wiring 2 are formed with an insulating film 3 such as 5j02 interposed therebetween. The two are brought into contact to establish an electrical connection. The first wiring 1 is the aforementioned two-layered electrode wiring, and is composed of a polycrystalline silicon film +a and a metal film 1. b
It is constructed by laminating layers. The second wiring 2 is made of polycrystalline silicon high melting point metal or high melting point metal silicide, and is in contact with the metal film 1b of the first wiring 1 in the connection hole 4. In addition, in Fig. 3, 5 is P
A semiconductor substrate such as a type silicon substrate, and 6 an insulating film such as a 5iOz film serving as a gate oxide film or the like.

According to such a configuration, high-speed circuit operation is possible by using the first wiring 1 having a two-layer structure, so high-speed access is possible in, for example, a memory, and multilayer wiring +11 yen is possible. Because of the structure, the wiring area can be substantially reduced, so that the semiconductor device can be configured in a small size.

[Problems to be Solved by the Invention] In the semiconductor device as described above, when the second wiring 2 is made of, for example, polycrystalline silicon, when it is formed by low pressure CVD (chemical vapor deposition),
Before the pressure inside the CVD reactor is reduced, the portion of the metal film 1bQ exposed from the connection hole 4 is exposed to the atmosphere at 400 to 700°C. As a result, an oxide insulating film is formed on the exposed portion of the metal film 1+ by a reaction between oxygen in the atmosphere and the metal film 1b, and this oxide insulating film forms a connection between the metal film 1b and the second wiring 2. Problems such as an increase in contact resistance between the two or an electrical open circuit between the two occur, which hinders the improvement of the operating speed of semiconductor devices and causes problems such as poor yield. Ta. This also applies to the case where the second wiring 2 is made of a high melting point metal or a high melting point metal silicide.

An object of the present invention is to provide a semiconductor device which can solve two technical problems and improve the operating speed and yield.

[Means for Solving Problem 1] A semiconductor device of the present invention includes a first interconnection formed by laminating a polycrystalline silicon film and a metal layer, and a first interconnection formed by laminating the first interconnection with an insulating film interposed therebetween. 2 wiring, and the first wiring and the second wiring are brought into contact with each other through a contact hole formed in the insulating film, wherein the second wiring is connected to a plurality of the first wirings. It is characterized by being in contact with a crystalline silicon film.

[Function] According to the configuration of the present invention, among the polycrystalline silicon film and the metal film that constitute the second wiring III and the first wiring,
Since the first and second wirings are brought into contact with a polycrystalline silicon film that is difficult to oxidize, and thus achieve mutual electrical connection between the first and second wirings, Unlike the conventional method, an oxide insulating film is not formed between the two, and therefore the contact resistance between the two can be significantly lowered, and the electrical connection between the two can be ensured.

〔Example〕

FIG. 1 is a sectional view showing the basic structure of a semiconductor device according to an embodiment of the present invention. In this semiconductor device, an insulating film 16 such as S]02, which serves as a gate oxide film, is formed on the surface of a semiconductor substrate 15 such as a P-type silicon substrate, and this insulating film 1
6, a first wiring 11° insulating film 13. A semiconductor device having a multilayer wiring structure in which second wirings 12 are sequentially stacked, the first and second wirings 1.1.12 are brought into contact with each other through a connection hole I4 formed in an insulating film 13, This is to obtain an electrical connection between the two. The first wiring 11 includes, in order from the insulating film 16 side, a polycrystalline silicon film 11a and a metal film 11 made of a high melting point metal or a high melting point metal silicide.
The wiring has a two-layer structure in which the Further, the second wiring 12 is made of polycrystalline silicon, a high melting point metal, or a high melting point metal silicide.

In this embodiment, the metal film 11b is not formed in the vicinity of the connection hole 14, so the second wiring 12 is in contact with the polycrystalline silicon film 11a in the connection hole 14.

The polycrystalline silicon film 11a is less likely to be oxidized than the metal films 1] and b, and therefore, for example, the second wiring 1
2, even if the portion exposed from the connection hole 14 of the polycrystalline silicon film 1, ]a is exposed to high temperature atmosphere, an oxidized H1 film will not be formed on the exposed portion. , therefore, the second wiring 12 and the metal film 1
1. A good electrical connection is achieved with a.

FIG. 2 is a cross-sectional view for explaining a method of manufacturing the semiconductor device shown in FIG. 1. 1) Mold (100) 100cm
A film with a thickness of 500 nm is formed on the surface of the silicon substrate 15 by thermal oxidation.
A polycrystalline silicon film 1 with a thickness of 300 nm and containing about L x 1020 cm of phosphorus over the entire surface of the 5iOz film 16 is formed.
, a are formed by low pressure CVD (chemical vapor deposition). This state is shown in FIG. 2(1).

Next, as shown in FIG. 2 (2), the polycrystalline soric film 1
．． A 5iOz film 13a with a thickness of 300 nm is formed on the entire surface of the metal film 11a by CVD method.
The 5iOz films 1 and 3a in the region S1 where the film 2b is to be formed are removed by photoetching.

Furthermore, as shown in FIG. 2(3), the area S indicated by 111f
] A metal film 1.1b is formed. This metal film], 1
．． For example, when a tungsten film is used as b, the tungsten film can be formed by selective CVD in which tungsten hexafluoride gas is reduced with hydrogen gas. The film thickness is 300 nm.

From the state shown in Figure 2 (3), 5 with a film thickness of 500 nm
iOz membrane 1. ．． 3b is formed by CVD method or the like.

In this way, the connection hole 1 is formed in the insulating film 13 composed of the 5iOz films 13a and 13b by photo-etching.
form 4. This state is shown in FIG. 2 (4).

From this state, the second wiring 12 is formed, and this state is shown in FIG. 2(5). When the second wiring 12 is made of polycrystalline silicon, for example, the second wiring 12 can be formed by low pressure CVD.

In the semiconductor device manufactured in this way, when the second wiring 12 is formed by, for example, a low pressure CV'D method, it is the polycrystalline silicon film 11a that is exposed from the connection hole 14. As mentioned above, this polycrystalline silicon film 11a is less likely to be oxidized than the metal film 11b, so even if it is exposed to high temperature air before the pressure inside the CVD reactor is reduced, an oxide film will not be formed on its surface. There are no words. Therefore, the second
An insulating film is not interposed between the wiring 12 and the polycrystalline silicon film 11a, and therefore, good electrical connection between the first and second wirings 11 and 12 is achieved through contact between the two. It turns out.

By establishing a good connection between the first wiring 11 and the second wiring 12 in this way, the contact resistance between them can be reduced and the semiconductor device can operate at high speed. Furthermore, since it is possible to reliably prevent the gap between the first and second wirings 11 and 12 from becoming open, the yield of semiconductor devices can be significantly improved.

In the above-mentioned embodiment, tungsten 1jψ formed by selective CVD is used as the metal film 11b of the first wiring 11. Melting point metal I
A high melting point metal silicide film such as a tungsten silicide film formed by a CVD method or a molybdenum silicide film formed by a sputtering method can be used. Furthermore, as the material for the second wiring 12, not only polycrystalline silicon but also a high melting point metal, a high melting point metal silicide, or the like can be used.

〔Effect of the invention〕

As described above, according to the semiconductor device of the present invention, an oxide insulating film is not formed between the first wiring and the second wiring as in the conventional case, and therefore the contact resistance between the two is significantly reduced. Moreover, the electrical connection between the two can be ensured.

As a result, the operating speed of the semiconductor device can be improved, and the wiring connections can be made reliably, thereby significantly improving the yield of the semiconductor device.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the basic structure of a semiconductor device according to an embodiment of the present invention, FIG. 2 is a sectional view illustrating its manufacturing method, and FIG. 3 is a sectional view showing a conventional technique. . 11...First wiring, lta...Polycrystalline silicon film, 1b...Metal film, 12...Second wiring, 13...Insulating film, 14...Connection hole ■, -<D Ln

Claims (1)

[Scope of Claims] A first wiring in which a polycrystalline silicon film and a metal film are laminated, and a second wiring in which a polycrystalline silicon film and a metal film are laminated with an insulating film interposed therebetween; The first connection hole formed
What is claimed is: 1. A semiconductor device in which a wiring and a second wiring are in contact with each other, wherein the second wiring is in contact with a polycrystalline silicon film of the first wiring.