JP2857170B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a method for manufacturing a semiconductor device having low contact resistance.

2. Description of the Related Art In general, an alloy mainly containing aluminum (Al), for example, an aluminum alloy containing silicon (Si) is used as an electrode and wiring material of a semiconductor device.

When Al containing no Si is used as an electrode / wiring material, during heat treatment, Si diffuses into Al at the contact portion between the Al film and the impurity diffusion layer of the silicon substrate, and alloy pits are generated, thereby causing a leakage phenomenon. May cause.

In order to prevent the occurrence of such a phenomenon, Al-Si alloys containing an excessive amount of Si (usually 1% or more) exceeding the solid solubility limit in Al have been widely used. However, when an Si-excess Al-Si alloy is used, Si precipitates at the contact portion, and the contact resistance often increases.
As the contact window becomes finer with the increase in the degree of integration of semiconductor elements, it has been strongly desired to suppress the occurrence of such a phenomenon.

In order to solve such a problem, in recent years, a wiring structure in which a high-melting-point metal is deposited thinly and an Al-Si alloy is deposited on the high-melting-point metal film, that is, a so-called barrier metal wiring, has been put into practical use.

Hereinafter, a manufacturing process of a conventional MOS type semiconductor device employing a barrier metal wiring having a titanium nitride / titanium (TiN / Ti) structure will be described with reference to FIG.

As shown in FIG. 2A, a selective oxidation (LOCOS) film 2, a gate oxide film 3, and a polycrystalline silicon gate 4 are sequentially formed on a semiconductor substrate 1 made of N-type Si.
B ⁺ or BF ₂ ⁺ is implanted by an ion implantation method to form a source / drain diffusion layer 5.

Thereafter, as shown in FIG. 2 (b), a heat treatment is performed at a temperature of 900 ° C. in an oxidizing atmosphere containing oxygen (O ₂ ) or water vapor to form a film on the drain / source diffusion layer 5 and the polysilicon. A silicon oxide film 6 having a thickness of 200 ° is formed on the gate 4.

Next, as shown in FIG. 2C, a silicon nitride film 7 having a thickness of about 500 ° is formed on the silicon oxide film 6 by a low pressure CVD method. Further, as shown in FIG. 2D, an interlayer insulating film 8 made of boron-phosphorus-containing glass (BSPG) is formed thereon by CVD.
After being formed to a thickness of about 5000 ° by a method or the like, heat treatment is performed in an oxidizing atmosphere containing water vapor at a temperature of 900 ° C. to melt and flatten the interlayer insulating film 8.

Next, as shown in FIG. 2 (e), the interlayer insulating film 8, the silicon nitride film 7 and the silicon oxide film 6 are selectively removed by a photolithography method, and the contact window reaching the drain / source diffusion layer 5 is formed. Is formed, a titanium film 9 having a thickness of about 200 ° is formed by a sputtering method. Subsequently, by sputtering Ti in an atmosphere containing nitrogen (N ₂ ) and argon (Ar), a titanium nitride (TiN) film 10 having a thickness of about 1000 ° is formed. Further, an Al-Si alloy film is formed thereon by a sputtering method, and thereafter, an Al-Si electrode 11 is formed by a photolithography method, thereby completing a MOS semiconductor device.

SUMMARY OF THE INVENTION In a semiconductor device having a barrier metal structure using a Ti film 9 and a TiN film 10 obtained by a conventional method as described above, the source / drain diffusion layer 5, the Al-Si electrode 11, It was found that the contact resistance of the sample was very high.

This is because a Ti film 9 and a TiN film 10 are interposed between the source / drain diffusion layer 5 and the Al-Si electrode 11, and after the source / drain diffusion layer 5 is formed, the semiconductor substrate 1 is oxidized to form a silicon oxide film 6 When the silicon oxide film 6 is grown, the impurities in the source / drain diffusion layer 5 are taken into the silicon oxide film 6 to reduce the impurity concentration on the surface of the source / drain diffusion layer 5. Between Al-Si electrode 11
It is clear that the barrier metal structure using the Ti film 9 and the TiN film 10 is generated in combination.

An object of the present invention is to provide a method of manufacturing a semiconductor device capable of effectively preventing an increase in contact resistance between an electrode having a barrier metal structure using such a Ti film 9 and a TiN film 10 and a semiconductor substrate. And

Means for Solving the Problems In order to solve the above-mentioned problems, in the method of the present invention, a semiconductor substrate is first heat-treated in an oxidizing atmosphere to form a silicon oxide film, and then impurity ions are passed through the silicon oxide film. Is selectively implanted to form an impurity diffusion layer, and a silicon nitride film and an interlayer insulating film are sequentially formed on the silicon oxide film, and then reach the impurity diffusion layer on the interlayer insulating film, the silicon nitride film, and the silicon oxide film. A contact window is formed, a titanium film and a titanium nitride film are sequentially formed so as to be in contact with the impurity diffusion layer at the contact window, and an electrode layer is further formed thereon.

After a silicon oxide film is formed on a semiconductor substrate, impurities are implanted into the semiconductor substrate by an ion implantation method. Therefore, the incorporation of impurities into the silicon oxide film can be prevented, and the surface impurity concentration of the source / drain diffusion layers can be reduced. It does not decrease, and Ti
With a barrier metal structure using a film and a TiN film, it has become possible to form an electrode with low contact resistance.

Embodiment An embodiment of a method for manufacturing a semiconductor device according to the present invention will be described below with reference to FIG.

As shown in FIG. 1 (a), a selective oxidation (LOCOS) film 2, a gate oxide film 3, and a polycrystalline silicon gate 4 are sequentially and selectively formed in a predetermined region on a semiconductor substrate 1 made of N-type Si. After that, as shown in FIG. 2B, in an oxidizing atmosphere containing O ₂ or water vapor, for example, 90
A heat treatment is performed at a temperature of 0 ° C. to form a silicon oxide film 6 having a thickness of 200 ° on the semiconductor substrate 1 and the polycrystalline silicon gate 4.
To form

Next, as shown in FIG. 1 (c), B ⁺ or BF ₂ ⁺ is implanted into a predetermined region of the semiconductor substrate 1 through the silicon oxide film 6 by an ion implantation method. The source / drain diffusion layer 5 is formed by performing an annealing process at a temperature of about.

Then, as shown in FIG. 1 (d), a silicon nitride film 7 having a thickness of about 500 ° is formed on the silicon oxide film 6 by a low pressure CVD method, and further, as shown in FIG. 2 (e). An interlayer insulating film 8 made of glass containing boron and phosphorus (BSPG) is formed thereon.
After depositing and forming to a thickness of about 5000 mm by the CVD method, heat treatment is performed in a water vapor atmosphere to melt and flatten the interlayer insulating film 8.

Next, as shown in FIG. 1 (f), the interlayer insulating film 8, the silicon nitride film 7, and the silicon oxide film 6 are selectively removed by a known photolithography method to reach the drain / source diffusion layer 5. After forming the contact window, a Ti film 9 having a thickness of about 200 ° is formed by a sputtering method. Subsequently, Ti is sputtered in an atmosphere containing N ₂ and Ar to form a TiN film 10 to a thickness of about 1000 °. Furthermore, after forming an Al-Si alloy film on it by sputtering,
An Al-Si electrode 11 is formed to complete a MOS semiconductor device.

In the above method, when BF ₂ ⁺ is used as impurity ions and the implantation amount is 3 × 10 ¹⁶ cm ⁻² , the area is 1 × 1
The contact resistance at the μm ² contact portion was about 75Ω. On the other hand, according to the conventional method, the contact resistance was several hundreds Ω when the impurity, the amount of implantation, and the contact area were the same.

As described above, when a semiconductor device having a barrier metal structure using the Ti film 9 and the TiN film 10 is manufactured, the contact resistance between the semiconductor substrate and the electrode can be significantly reduced by applying the method of the present invention. .

Instead of impurity ions into the _{^{BF 2 +, B +, P}} + or As
It is needless to say that the same effect can be obtained by using such a method.

Comparative Example When MoSi was used instead of TiN / Ti as a barrier metal, when a silicon oxide film was formed after BF ₂ ⁺ implantation, the contact resistance was about 120Ω, whereas BF ₂ ^{When +} was injected, it was about 100Ω. If the barrier metal structure is not used,
When the silicon oxide film was formed after the BF ₂ ⁺ injection, the resistance was about 250Ω, whereas when the BF ₂ ⁺ was injected after the silicon oxide film was formed, the resistance was about 200Ω.

In all cases, no sufficient decrease in contact resistance was observed,
It can be seen that a significant reduction in contact resistance can be realized only by the method of the present invention.

This indicates that the present invention has an excellent effect in the manufacture of a semiconductor device having a barrier metal structure using the Ti film 9 and the TiN film 10.

According to the method of the present invention, a silicon oxide film is formed on a semiconductor substrate, and then impurity ions are injected into the semiconductor substrate through the silicon oxide film to form an impurity diffusion layer, and further an insulating film is formed. Then, a contact window reaching the impurity diffusion layer is formed in the insulating film, a titanium film and a titanium nitride film are sequentially formed so as to be in contact with the impurity diffusion layer at the contact window, and an electrode layer is further formed thereon. .

According to this, the impurity is implanted into the semiconductor substrate by the ion implantation method after the silicon oxide film is formed, so that the incorporation of the impurity into the silicon oxide film can be prevented. Therefore, the surface impurity concentration of the source / drain diffusion layers is not substantially reduced, and the Ti film and the TiN
The contact resistance of an electrode having a barrier metal structure using a film can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a step-by-step cross-sectional view for explaining one embodiment of a method for manufacturing a semiconductor device of the present invention, and FIG. 2 is a step-by-step cross-sectional view for explaining one example of a conventional method for manufacturing a semiconductor device. . 1 ... N-type semiconductor substrate, 2 ... Selective oxidation (LOCOS) film,
3 ... gate oxide film, 4 ... polycrystalline silicon gate, 5
... Source / drain diffusion layer, 6 ... silicon oxide film, 7
... silicon nitride film, 8 ... interlayer insulating film, 9 ... titanium (Ti) film, 10 ... titanium nitride (TiN) film, 11 ... Al-Si
electrode

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/336 H01L 21/265 H 29/43 29/46 R // H01L 21/316 (72) Inventor Seiji Ueda Okadoma, Kadoma City, Osaka 1006 Matsushita Electronics Corporation (56) References JP-A-61-150377 (JP, A) JP-A-61-247073 (JP, A) JP-A-62-205951 (JP, A) JP 63-205951 (JP, A) JP-A-62-183142 (JP, A) JP-A-62-235575 (JP, A) JP-A-63-1690 (JP, A) Michitada Morisue supervised "LSI design technology" (Showa 62-9-30) Denki Shoin p. 302 end line -p. 304 line 1

Claims (1)

(57) [Claims] A step of selectively forming a gate oxide film and a gate on the semiconductor substrate and then heat-treating the semiconductor substrate in an oxidizing atmosphere to form a silicon oxide film; Selectively forming an impurity diffusion layer, performing a heat treatment in an inert gas, forming a silicon nitride film on the silicon oxide film, and forming an interlayer insulating film on the silicon nitride film. Forming a contact window on the interlayer insulating film, the silicon nitride film, and the silicon oxide film, the contact window reaching the impurity diffusion layer; and contacting the impurity window with the impurity diffusion layer at the contact window. And a step of sequentially forming a titanium nitride film, and a step of forming an electrode layer on the titanium nitride film. Production method.