JPH0638482B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming a diffusion layer that constitutes a source / drain.

[Conventional technology]

Conventionally, a method of forming a titanium silicide film on a source / drain diffusion layer has been used in order to reduce the sheet resistance of the source / drain diffusion layer having the LDD structure of a CMOS type semiconductor device and increase the operation speed ( For example, JP-A-61-287227). In this case, ion implantation of impurities for forming the high-concentration diffusion layer has been performed immediately after the titanium silicide film is formed.

[Problems to be solved by the invention]

In the conventional method of manufacturing a CMOS semiconductor device described above, impurities are ion-implanted using aluminum (A1) or a resist as a mask in order to form a high-concentration diffusion layer on a semiconductor substrate. However, when aluminum or a resist is directly formed on the titanium silicide film and ion implantation of impurities is performed as a mask, the titanium silicide film and aluminum react with each other to change the quality of the titanium silicide film or to remove the resist. The oxygen plasma treatment causes the titanium silicide film to be oxidized and deteriorated to increase the resistance of the titanium silicide film, thus degrading the reliability of the semiconductor device.

An object of the present invention is to provide a method for manufacturing a semiconductor device in which the titanium silicide film is not deteriorated and whose reliability is improved.

[Means for solving problems]

A method of manufacturing a semiconductor device according to the present invention comprises a step of forming a gate electrode on a semiconductor substrate via a gate oxide film, and ion implantation of impurities using the gate electrode as a mask to form a low concentration diffusion layer on the semiconductor substrate. A step of forming an insulating film on the entire surface including the low-concentration diffusion layer and then etching by an anisotropic etching method to form a sidewall made of an insulating film on the side surface of the gate electrode, and forming a titanium film on the entire surface After that, annealing is performed to form a titanium silicide film on the low-concentration diffusion layer, and then the unreacted titanium film is removed. After forming a silicon oxide film on the entire surface, impurities are passed through the silicon oxide film and the titanium silicide film. And ion implantation to form a high-concentration diffusion layer in the low-concentration diffusion layer.

〔Example〕

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

1A to 1E are cross-sectional views of a semiconductor chip shown in the order of steps for explaining an embodiment of the present invention, showing the case where the present invention is applied to a CMOS type semiconductor device.

First, as shown in FIG. 1A, a P-type silicon substrate 1
Phosphorus (P) is ion-implanted into the surface of 0, and then heat treatment is performed to form the N well 11. Next, boron (B)
Are ion-implanted to form the channel stopper 12, and then the field oxide film 13 is grown by the selective oxidation method. Next, the gate oxide film 1 is formed on the active region by thermal oxidation.
After forming No. 4, polysilicon is grown on this gate oxide film 14 and patterned to form a gate electrode 15. Boron (B) is injected into the P-channel side at 30 keV and energy and dose amount of 1 to 5 × 10 ¹³ cm ⁻² , and phosphorus (P) is injected into the N-channel side at 4
The P ⁻ diffusion layer 17 and the N ⁻ diffusion layer 1 are implanted with an energy and a dose of 0 keV and 5 to 10 × 10 ¹³ cm ⁻² , respectively.
6 is formed. Next, after growing a silicon oxide film by the chemical vapor deposition method, the entire surface of the silicon oxide film is anisotropically etched by the reactive ion etching method to form sidewalls 18 on both sides of the gate electrode 15.

Next, as shown in FIG. 1 (b), titanium (Ti) is formed on the entire surface of the silicon substrate by a sputtering method so as to have a film thickness of 400 to 800 Å, and then heated to about 600 ° C. by lamp annealing in a nitrogen atmosphere. After the titanium silicide film 19 is formed, unreacted titanium is removed with a mixed solution of ammonia, hydrogen peroxide solution and water. Then, the titanium silicide film 19 is reduced in resistance by heating to about 800 ° C. by lamp annealing in a nitrogen atmosphere. After that, silane (Hi
The silicon oxide film 20 is grown on the entire surface of the silicon substrate with a film thickness of about 200 Å by atmospheric pressure thermal chemical vapor deposition at a substrate temperature of 400 ° C. using H ₄ ) and oxygen (O ₂ ) as reaction gases.

Next, as shown in FIG. 1 (c), a mask 21 made of aluminum is formed only on the N-channel side, and then, using this mask 21, boron is energy only on the P-channel side with an energy of 30 keV and a dose amount of 5 to 10 ×. Ions are implanted under the condition of 10 ¹⁵ cm ⁻² to form the P ⁺ diffusion layer 22.

Next, as shown in FIG. 1 (d), after removing the mask 21 by etching with a phosphoric acid solution, a mask 21A made of aluminum is formed again only on the P channel side, and using this mask, the N channel side is formed. Arsenic (As) energy of 70 to 100 keV and dose of 5 to 10 × 10
Ion implantation is performed under the condition of ¹⁵ cm ⁻² to form the N ⁺ diffusion layer 24, thereby completing the source / drain diffusion layer of the LDD structure.

As shown in FIG. 1 (e) below, phosphorus glass (PSG)
The film 25 is grown by atmospheric pressure thermal chemical vapor deposition to obtain 900
After performing furnace annealing in a nitrogen atmosphere at a temperature of ℃, a contact hole is formed by reactive ion etching, an aluminum film is grown by a sputtering method, and patterned to form an aluminum electrode 26 to form a CMOS semiconductor device. Finalize.

As described above, according to this embodiment, the titanium silicide film 19 is formed.
Since the masks 21 and 21A made of aluminum are formed after the silicon oxide film 20 is formed thereon to ion-implant impurities, the reaction between aluminum and the titanium silicide film is prevented. Therefore, the titanium silicide film 19
Will not be altered.

Even when a resist is used as a mask for ion implantation, the oxygen plasma used for removing the resist does not directly contact the titanium silicide film, so that the titanium silicide film is not oxidized. Further, contaminants at the time of ion implantation of impurities are not mixed in the titanium silicide film.

In the above embodiment, the case where the silicon oxide film on the titanium silicide film is formed to a thickness of about 200Å by the vapor phase growth method has been described, but the substrate temperature is 400 ° C. and the RF sputtering method using the quartz target is used. The thickness may be about 100 to 300 Å. Since the silicon oxide film formed by the PF sputtering method is denser than that formed by the vapor phase growth method, it has a high barrier property against aluminum used as a mask for ion implantation of impurities. Further, unlike the case of the vapor phase growth method, the titanium silicide film does not come into contact with an oxidizing gas such as oxygen, so that the alteration of the titanium silicide film is further prevented.

〔The invention's effect〕

As described above, according to the present invention, a silicon oxide film is formed by a chemical vapor deposition method or a sputtering method on a semiconductor substrate on which a titanium silicide film is formed, and then ion implantation of impurities is performed to form a high concentration diffusion layer. As a result, even if an aluminum film or a resist film is used as a mask for impurity ion implantation, the silicon oxide film acts as a barrier, so that the aluminum and titanium silicide film do not react with each other, and the oxygen during the resist removal is eliminated. The plasma treatment does not oxidize or alter the titanium silicide film. Therefore, there is an effect that a highly reliable semiconductor device can be manufactured.

[Brief description of drawings]

1A to 1E are cross-sectional views of a semiconductor chip shown in the order of steps for explaining an embodiment of the present invention. 10 ... P-type silicon substrate, 11 ... N well, 12 ...
… Channel stopper, 13 …… Field oxide film,
14 ... Gate oxide film, 15 ... Gate electrode, 16 ...
N ^- diffusion layer, 17 ... P ^- diffusion layer, 18 ... Sidewall, 19 ... Titanium silicide film, 20 ... Silicon oxide film, 21, 21A ... Mask, 22 ... P ⁺ diffusion layer,
24 ... N ⁺ diffusion layer, 25 ... PSG film, 26 ... Aluminum electrode.

Claims (1)

[Claims] 1. A step of forming a gate electrode on a semiconductor substrate through a gate oxide film, a step of ion-implanting impurities using the gate electrode as a mask to form a low concentration diffusion layer on the semiconductor substrate, A step of forming an insulating film on the entire surface including the concentration diffusion layer and then etching by an anisotropic etching method to form sidewalls made of an insulating film on the side surface of the gate electrode; and a titanium film formed on the entire surface and then annealing. A step of forming a titanium silicide film on the low-concentration diffusion layer and then removing an unreacted titanium film, and a step of forming a silicon oxide film on the entire surface and then ion-implanting impurities through the silicon oxide film and the titanium silicide film. And a step of forming a high concentration diffusion layer in the concentration diffusion layer.