JPH04261047A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent the generation of failures, such as disconnection by forming a second metal wiring connected to a gate electrode on the surface of a second layer insulating film which covers a first layer insulating film. CONSTITUTION:There are installed a first layer insulating film 8 which covers a transistor prepared in an element region on a silicon substrate 1 and an element isolation region 2 and a second layer insulating film 15 which covers the first layer insulating film 8. A second metal wiring 10 connected to a gate electrode 3 of the transistor is formed on the surface of the second layer insulating film 15. The gate electrode 3 is constituted by a polysilicon film 6 formed on a gate oxide film 5 and a tungsten silicide film 7 formed in such a fashion that it may cover the polysilicon film 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly to its wiring structure.

0002

2. Description of the Related Art Conventionally, semiconductor devices have been constructed as shown in FIG. In other words, this figure 2
1 is a silicon substrate, 2 is an element isolation region for isolating transistors formed in the element region of the silicon substrate 1, 3 is a gate electrode constituting the transistor, and 4 is its source/drain. . This gate electrode 3 is composed of a polysilicon film 6 formed on a gate oxide film 5 and a tungsten silicide film 7 formed to cover this.

Further, an interlayer insulating film 8 is formed on the transistor and element isolation region 2, and metal interconnections 9 and 10 formed on the interlayer insulating film 8 are connected to the source/drain 4 and the transistor. The tungsten silicide film 7 that constitutes the gate electrode 3 is an interlayer insulating film 8.
They are connected through tungsten embedded in contact holes 11 and 12 formed in each of the contact holes 11 and 12, respectively.

Next, a method for manufacturing this semiconductor device will be explained.

First, element isolation regions 2 are formed by thermally oxidizing the surface of a prepared silicon substrate 1, and element regions in which transistors are to be formed between these element isolation regions 2 are exposed. Then, a gate oxide film 5 is formed on the exposed element region by thermal oxidation, a polysilicon film 6 is sequentially formed by CVD, and a tungsten silicide film 7 is formed by sputtering to form layers, and then these are patterned. and gate electrode 3
form.

Furthermore, after forming the source/drain 4 of the transistor by injecting impurities such as arsenic into the element region of the silicon substrate 1, boron phosphosilicate glass (BSPG) or the like is deposited by atmospheric pressure CVD. Then, an interlayer insulating film 8 that completely covers the transistor and element isolation region 2 is formed. Next, contact holes 11 and 12 are formed in the interlayer insulating film 8 at positions corresponding to the source/drain 4 and the gate electrode 3, respectively.
Tungsten is selectively embedded using VD or the like.

Subsequently, a metal layer is formed on the interlayer insulating film 8 by depositing aluminum or the like by CVD, and then this metal layer is patterned to form metal wirings 9 and 10. As a result, metal wiring 9,
10, source/drain 4 and gate electrode 3
The tungsten silicide film 7 is connected to the tungsten silicide film 7 through the tungsten embedded in the contact holes 11 and 12 of the interlayer insulating film 8.

[0008]

However, the semiconductor device having the conventional structure has the following disadvantages. That is, when tungsten is embedded in the contact holes 11 and 12 formed in the interlayer insulating film 8, as shown in FIG.
Only the tungsten embedded therein may protrude outward from the surface of the interlayer insulating film 8. Therefore, when metal wirings 9 and 10 are subsequently formed on the interlayer insulating film 8,
Since the coverage of the metal wiring 10 to be connected to the gate electrode 3 has deteriorated, as shown in FIG. Failures such as disconnection between the two may occur.

Note that here, only the tungsten in the contact hole 12 protrudes from the surface of the interlayer insulating film 8 because the tungsten formed on the tungsten silicide film 7 is more This is thought to be due to the fact that tungsten grows faster than the formed tungsten and that the thickness of the interlayer insulating film 8 around the contact hole 12 is thinner than the other parts.

The present invention was devised in view of these disadvantages, and is directed against tungsten that is formed on the tungsten silicide film constituting the gate electrode and protrudes to the outside of the surface of the interlayer insulating film. To provide a semiconductor device and a method for manufacturing the same, which can easily form properly connected metal wiring even when the semiconductor device is connected, and which can prevent defects such as disconnection and improve reliability. It is an object.

[0011]

[Means for Solving the Problems] In order to achieve the above object, a semiconductor device according to the present invention includes a transistor formed in an element region of a silicon substrate and a first interlayer insulating film covering an element isolation region. , a second interlayer insulating film covering the first interlayer insulating film, and a first interlayer insulating film formed on the source/drain of the transistor and the surface of the first interlayer insulating film.
The metal wiring is connected via tungsten embedded in the contact hole formed in the first interlayer insulating film, while the tungsten silicide film forming the gate electrode of the transistor and the surface of the second interlayer insulating film are connected. The first interlayer insulating film is embedded in the contact hole of the first interlayer insulating film and is connected to the second metal wiring through the tungsten that is exposed on the surface of the second interlayer insulating film.

[0012] Furthermore, in the method for manufacturing a semiconductor device according to the present invention, an element region and an element isolation region are formed on a silicon substrate, a transistor is built in this element region, and then a transistor is formed in the element region.
A step of forming a first interlayer insulating film that completely covers these, forming contact holes communicating with each of the source/drain and gate electrodes of the transistor in the first interlayer insulating film, and embedding tungsten into these contact holes. a step of forming a first metal wiring connected to the source/drain of the transistor via tungsten on the surface of the first interlayer insulating film; and a step of forming a first metal wiring connected to the source/drain of the transistor via tungsten; A step of forming a second interlayer insulating film on the first interlayer insulating film with a thickness corresponding to the protruding height of the tungsten that protrudes above the surface of the interlayer insulating film, and a tungsten silicide film forming the gate electrode of the transistor. and forming a second metal wiring connected via tungsten on the surface of the second interlayer insulating film.

[0013]

[Operation] According to the above structure, the source/drain of the transistor and the first metal wiring formed on the surface of the first interlayer insulating film are connected through the tungsten embedded in the contact hole of the first interlayer insulating film. On the other hand, the tungsten silicide film constituting the gate electrode of the transistor and the second metal wiring formed on the surface of the second interlayer insulating film protrude from the first interlayer insulating film and connect to the surface of the second interlayer insulating film. connected through exposed tungsten. In other words, the tungsten of the gate electrode is formed on the surface of the first interlayer insulating film through the tungsten that remains protruding from the surface.
A second metal wiring connected to the silicide film is not formed, and this second metal wiring is connected to the first metal wiring with protruding tungsten.
It is formed on the surface of a second interlayer insulating film that covers the interlayer insulating film. Therefore, the coverage when forming the second metal wiring is not deteriorated, and the second metal wiring and the tungsten silicide film that constitutes the gate electrode of the transistor are reliably connected via tungsten. become.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings.

FIG. 1 is a cross-sectional view showing a schematic structure of a semiconductor device according to an embodiment of the present invention.

In FIG. 1, the same reference numerals are given to the same or corresponding parts as in FIG. 2 showing the conventional example.

The semiconductor device according to this embodiment includes a first interlayer insulating film 8 that covers the transistor formed in the element region of the silicon substrate 1 and the element isolation region 2, and a second interlayer insulating film 8 that covers the first interlayer insulating film 8. a second metal wiring 10 comprising an interlayer insulating film 15 and connected to the gate electrode 3 of the transistor;
This embodiment differs greatly from the conventional example in that it is formed on the surface of the second interlayer insulating film 15. That is, in FIG. 1, reference numeral 1 is a silicon substrate, 2 is an element isolation region, 3 is a gate electrode constituting a transistor, and 4 is its source/drain. This gate electrode 3 is composed of a polysilicon film 6 formed on a gate oxide film 5 and a tungsten silicide film 7 formed to cover this.

Further, a first interlayer insulating film 8 is formed on the transistor and element isolation region 2, and a first metal wiring 9 formed on the first interlayer insulating film 8 and the source of the transistor are connected to each other. - They are connected to the drains 4 through tungsten embedded in contact holes 11 formed in the first interlayer insulating film 8.

Further, a second interlayer insulating film 15 is formed on the first interlayer insulating film 8, and the tungsten embedded in the contact hole 12 located above the gate electrode 3 of the transistor forms the second interlayer insulating film 15. It is exposed on the surface of the membrane 15. A second metal interconnect 10 is formed on the surface of the second interlayer insulating film 15, and the second metal interconnect 10 and the tungsten silicide film 7 forming the gate electrode 3 are separated from each other by the first interlayer insulating film 15. The contact holes 12 of No. 8 are filled with tungsten and exposed on the surface of the second interlayer insulating film 15 for connection.

Next, a method for manufacturing the semiconductor device according to this embodiment will be explained.

First, as in the conventional example, an element isolation region 2 is formed on the surface of a silicon substrate 1 prepared in advance, and the gate electrode 3 and source/drain 4 of the transistor are formed in the exposed element region.・Phosphorsilicate glass (
A first interlayer insulating film 8 that completely covers the transistor and element isolation region 2 is formed by depositing BSPG (BSPG) or the like. Contact holes 11 and 12 communicating with the source/drain 4 and gate electrode 3 are formed in the first interlayer insulating film 8 at positions corresponding to the source/drain 4 and the gate electrode 3, respectively.
After forming these contact holes 11, 12
Tungsten is selectively embedded inside by CVD or the like. At this time, based on the above-mentioned reason, the tungsten embedded in the contact hole 12 communicating with the tungsten silicide film 7 of the gate electrode 3 protrudes outward beyond the surface of the first interlayer insulating film 8. I will do it.

Therefore, a first metal wiring 9 is formed on the surface of the first interlayer insulating film 8 by depositing aluminum or the like by CVD and patterning, and this first metal wiring 9 is connected to the source/drain of the transistor. 4 are connected to each other through tungsten embedded in the contact hole 11 of the first interlayer insulating film 8. Subsequently, a second interlayer insulating film 15 such as a silicon oxide film is formed on the first interlayer insulating film 8 by plasma CVD. Note that at this time, the film thickness of the second interlayer insulating film 15 is made to correspond to the protruding height of the tungsten that is embedded in the contact hole 12 leading to the gate electrode 3 of the transistor and protrudes from the surface of the first interlayer insulating film 8. It is being

[0023] After that, aluminum etc.
A second metal wiring 10 is formed on the surface of the second interlayer insulating film 15 by depositing by VD and patterning, and the second metal wiring 10 and the tungsten silicide film 7 forming the gate electrode 3 of the transistor are formed. are connected to each other through tungsten embedded in the contact hole 12. As a result, a semiconductor device having the structure shown in FIG. 1 is completed.

[0024]

[Effects of the Invention] As explained above, according to the present invention,
Only the first metal wiring connected to the source and drain of the transistor is formed on the surface of the first interlayer insulating film covering the transistor and the element isolation region, and the second metal wiring connected to the gate electrode is formed on the surface of the first interlayer insulating film covering the transistor and the element isolation region. A second layer covering the first interlayer insulating film
It is formed on the surface of the interlayer insulating film. Therefore, the coverage when forming the second metal wiring is no longer deteriorated as in the conventional example, and the transistor is The gate electrode and the second metal wiring can be easily and reliably connected. Therefore, it is possible to effectively prevent the occurrence of defects such as wire breakage, and as a result, the reliability of the semiconductor device can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a schematic structure of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a schematic structure of a semiconductor device according to a conventional example.

[Explanation of symbols]

1 Silicon substrate 2 Element isolation film 3 Gate electrode 4 Source/drain 7 Tungsten silicide film 8 First
Interlayer insulation film 9 First metal wiring 10 Second metal wiring 11 Contact hole 12 Contact hole 15 Second interlayer insulation film

Claims (2)

[Claims] 1. A first interlayer insulating film covering a transistor and an element isolation region formed in an element region of a silicon substrate;
a second interlayer insulating film that covers the first interlayer insulating film, and the source/drain of the transistor and the first metal wiring formed on the surface of the first interlayer insulating film are formed on the first interlayer insulating film. The tungsten silicide film constituting the gate electrode of the transistor and the second metal wiring formed on the surface of the second interlayer insulating film are connected via the tungsten embedded in the contact hole. A semiconductor device characterized in that the semiconductor device is connected via tungsten embedded in a contact hole of an insulating film and exposed on the surface of a second interlayer insulating film. 2. A step of forming an element region and an element isolation region on a silicon substrate, forming a transistor in this element region, and then forming a first interlayer insulating film that completely covers these, and a source of the transistor.・A step of forming contact holes leading to each of the drain and gate electrodes in the first interlayer insulating film and burying tungsten in these contact holes, and a first metal wiring connected to the source/drain of the transistor via tungsten. The first
A process of forming a second film on the surface of the interlayer insulating film, and a second film having a thickness corresponding to the protruding height of the tungsten embedded in the contact hole leading to the gate electrode of the transistor and protruding above the surface of the first interlayer insulating film. A step of forming an interlayer insulating film on the first interlayer insulating film, and forming a second metal wiring on the surface of the second interlayer insulating film to be connected via tungsten to the tungsten silicide film that constitutes the gate electrode of the transistor. A method for manufacturing a semiconductor device, comprising the steps of: