JP2558124B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for improving contact between a polycide wiring and an underlying metal or a semiconductor substrate in manufacturing a semiconductor device, and polycide (two-layer structure of silicide and polysilicon).
With the aim of providing a method for reducing the contact resistance between the metal and the underlying metal or the semiconductor substrate, a step of sequentially depositing an insulating film and a polysilicon film on the lower surface of the metal, A method of manufacturing a semiconductor device is characterized by including a step of forming a contact window reaching a metal and a step of depositing a silicide film on the entire surface including the contact window and patterning the silicide film and the polysilicon film. .

[Industrial applications]

The present invention relates to a method for improving the contact between polycide wiring and an underlying metal or semiconductor substrate in the manufacture of semiconductor devices.

[Conventional technology]

As a wiring material, a structure called polycide of [polysilicon + silicide] is drawing attention. An example of the structure is shown in FIG. 3, in which 31 is a base, for example, a silion substrate, 32 is a polysilicon film, and 33 is a silicide [for example, titanium silicide (TiSi ₂ )].

The reason why such polycide attracts attention is that, for example, when polycide is used as a gate electrode, compared with a case where a metal and an oxide film are directly contacted with an underlying gate oxide film (SiO ₂ film), polysilicon is used. This is because it is more stable to make contact via. In addition, the oxidation mechanism of silicide during oxidation will be described with reference to FIG. 4. When the silicide film 33 is heat-treated to form an oxide film (SiO ₂ film) 34, the silicide film 33 has a [metal (M ) -Si ₂ + Si], and in the oxidation, Si having the above structure is oxidized to become SiO ₂ . As a result, the metal-to-Si ratio (M / Si) becomes large and Si
The base of the O ₂ film 34 may become unstable and the oxide film may peel off, or the silicide film may peel off.

FIG. 5 shows a polysite in which the polysilicon film 32 is provided under the silicide film 33. At this time, since the SiO ₂ film 34 is easily formed by Si in the polysilicon film during oxidation, Si does not move, metal-
The structure of Si ₂ + Si is maintained as it is, and the base of the SiO ₂ film 34 is stable. For this reason, the polycide structure has come to be used.

[Problems to be solved by the invention]

When the polycide and the metal are brought into contact with each other, as shown in the sectional view of FIG. 6, a SiO ₂ film for insulation is provided on the metal 41.
42 is formed, a contact window 43 is opened in the SiO ₂ film 42, and then a polysilicon film 44 and a silicide film 45 are sequentially deposited on the entire surface including the contact window 43.

In the above example, since polysilicon is a semiconductor, high concentration impurities [phosphorus (P), arsenic (As),
If boron (B) or the like is not diffused or ion-implanted, the contact resistance of silicide / polysilicon / metal does not decrease. Further, there is a problem that the number of steps is increased by the doping of the impurities, and the manufacturing yield of the semiconductor device is reduced.

Therefore, it is an object of the present invention to provide a method for reducing the contact resistance between polycide (two-layer structure of silicide and polysilicon) and an underlying metal or a semiconductor substrate.

[Means for solving problems]

The problems described above include the steps of sequentially depositing an insulating film and a polysilicon film on the lower surface of a metal, the step of opening a contact window reaching the underlying metal in the polysilicon film and the insulating film, and the entire surface including the contact window. This is accomplished by a method for manufacturing a semiconductor device, which includes the steps of depositing a silicide film and patterning the silicide film and the polysilicon film.

[Action]

In the electrode wiring formed by the above method, the metal and the silicide are in direct contact with each other in the contact window where the base and the metal are in contact with each other, and polysilicon is not interposed, so that the contact resistance can be suppressed to a low level. Has a three-layer structure of insulating film / polysilicon / silicide, so that the influence of the insulating film on the silicide is blocked by polysilicon, so that good electrode wiring can be obtained and it is necessary to dope the polysilicon. Since it is not provided, the number of steps is smaller than that of the conventional example.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to an embodiment shown in the drawings.

FIG. 1 shows the principle of the present invention. According to the principle, polysilicon is not interposed in the electrode portion in contact with the underlying metal, and polysilicon is interposed in the wiring portion on the insulating film so that the lower layer with respect to the upper silicide layer The effect of the insulating film is blocked.

In the present invention, as shown in FIG. 1 (a), an insulating SiO ₂ film 12 and a polysilicon film 13 are sequentially formed on the underlying metal 11.
Are sequentially deposited, and then a contact window 14 reaching the underlying metal 11 through the polysilicon film 13 and the SiO ₂ film 12 is opened as shown in FIG.

Next, as shown in FIG. 3C, a silicide film 15 is deposited on the entire surface including the contact window 14.

Then, by patterning the silicide film and the polysilicon film to form the electrode wiring shown in the plan view of FIG. 3D and the perspective view of FIG. 2E, the metal 11 and the silicide film 15 at the contact portion and the wiring portion are formed. In this, a three-layer structure of SiO ₂ / polysilicon film / silicide film is obtained, and stable electrode wiring with low contact resistance can be obtained.

 An embodiment of the invention is shown in cross section in FIG.

See Fig. 2 (a): The silicon substrate 21 is oxidized and a 6000 Å thick layer is formed on its surface.
A SiO ₂ film 22 is formed, and a polysilicon film 23 and a tungsten silicide film (WSix) 24 are deposited to prepare a tungsten polycide wiring, and an SiO ₂ film 25 for insulation is formed thereon.
The thickness of 3000 Å, the polysilicon film 26 on the SiO ₂ film 25 10
Grow to a thickness of 00Å.

Refer to FIG. 2B: A contact window 27 is opened through the polysilicon film 26 and the SiO ₂ film 25 to reach the WSix film 24.

See FIG. 2 (c): Titanium silicide (TiSi) is formed on the entire surface including the contact window 27.
x) A film 28 is deposited, titanium polycide wiring is formed on the SiO ₂ film 25, and electrodes of dangsten polycide and titanium silicide are formed on the contact window portion, and annealing is performed to reduce the resistance. . Hereinafter, patterning as described with reference to FIGS. 1D and 1E is performed.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain a contact portion having low resistance and a stable polycide wiring in a smaller number of steps as compared with the conventional example, and it is effective to improve the manufacturing yield of the semiconductor device and to improve the reliability. is there.

In the above example, the case of making contact with a metal was described, but the scope of application of the present invention is not limited to that case, but extends to the case of making contact with a semiconductor substrate.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of the present invention, in which (a) to (c) are shown.
Is a sectional view, (d) is a plan view, (e) is a perspective view, FIGS. 2 (a) to (c) are sectional views of an embodiment of the present invention, FIG. 3 is a sectional view of a polycide structure, 4 is a sectional view for explaining oxidation of silicide, FIG. 5 is a sectional view for explaining oxidation of polycide, and FIG. 6 is a sectional view for a conventional example. In FIGS. 1 and 2, 11 is a metal, 12 is a SiO ₂ film, 13 is a polysilicon film, 14 is a contact window, 15 is a silicide film, 21 is a silicon substrate, 22 is a SiO ₂ film, and 23 is polysilicon. A film, 24 is a tungsten silicide film, 25 is a SiO ₂ film, 26 is a polysilicon film, 27 is a contact window, and 28 is a titanium silicide film.

Claims (2)

(57) [Claims] 1. A step of sequentially depositing an insulating film (12) and a polysilicon film (13) on a lower surface of a metal (11), the polysilicon film (13) and the insulating film (12) being a base metal (1).
A step of forming a contact window (14) reaching 1) and a step of depositing a silicide film (15) on the entire surface including the contact window (14) and patterning the silicide film (15) and the polysilicon film (13). A method of manufacturing a semiconductor device, comprising: 2. The method according to claim 1, wherein the underlying metal is polycide (23, 24) formed on a semiconductor substrate (21).