JP2001291862A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor which suppresses the short channel effect by forming a shallow impurity diffusion layer. SOLUTION: This method for manufacturing a semiconductor device comprises a step of forming a gate oxide film 5 on a silicon substrate 1, a step of forming a gate electrode 7 on the gate oxide film 5, a step of removing any insulating film on the surface of the silicon substrate 1 in the source/drain region and exposing the surface of the silicon substrate 1 in the source/drain area, a step of implanting impurity ions into the relatively shallow region of the silicon substrate 1 with the gate electrode 7 as a mask, a step of forming a cap film 15 for preventing outward diffusion on the exposed silicon substrate 1, and a step of carrying out heat treatment for activating the impurity ions implanted into the silicon substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device in which a short channel effect is suppressed.

[0002]

2. Description of the Related Art FIG. 5 is a cross-sectional view for explaining a conventional method for manufacturing a semiconductor device. First, the silicon substrate 10
After forming a LOCOS oxide film 103 for element isolation in 1, a gate oxide film 105 is formed on the silicon substrate 101 between the LOCOS oxide films 103 by a thermal oxidation method. Next, the gate length is set to 0.
The gate electrode 107 having a thickness of about 13 to 0.18 μm is formed. Thereafter, impurity ions (not shown) are implanted into the silicon substrate 101 using the gate electrode 107 as a mask, and the silicon substrate 101 is subjected to a heat treatment. As a result, the diffusion layer 110 in the extension region is formed on the silicon substrate 101.
Is formed.

[0005] Next, S is formed on the entire surface including the gate electrode 107.
By depositing an iO ₂ film and etching back the SiO ₂ film, a sidewall 1 is formed on the side wall of the gate electrode 107.
11a is formed. And further, the silicon substrate 101
The oxide film on the surface is removed.

Thereafter, impurity ions 113 are implanted into a shallow region of the silicon substrate 101 with relatively low acceleration energy using the gate electrode 107, the sidewalls 111a, and the LOCOS oxide film 103 as a mask.

Next, the silicon substrate 101 is annealed for a short time at a low temperature to activate the impurity ions 113, so that the silicon substrate 101 has a shallow source / source.
A diffusion layer (not shown) for the drain region is formed.

[0006]

By the way, the above conventional art
In the method of manufacturing a semiconductor device, the gate length is 0.13 to 0.1.
In order to form a fine MOSFET of about 18 μm,
SiO on the surface of the recon substrate _TwoFilm removed (silicon
Lower acceleration energy with the substrate surface exposed)
Impurity ions 113 in a shallow region of the silicon substrate 101
And annealed. Such a shallow area
Implanting impurity ions into the
It is a thing.

However, if annealing for activating impurities is performed with the surface of the silicon substrate exposed as described above, the impurity ions 113 may diffuse outward from the surface of the silicon substrate (OutDiffusion). As a result, the impurity concentration of the diffusion layer decreases, and the short channel effect cannot be sufficiently suppressed.

On the other hand, when an impurity is ion-implanted into the silicon substrate at a low acceleration energy while the oxide film on the surface of the silicon substrate is not removed and the oxide film is formed on the surface.
The impurity ions are blocked by the oxide film and do not reach the silicon substrate. When the energy of ion implantation is increased, impurity ions reach the silicon substrate, but an impurity diffusion layer having a small depth cannot be formed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a semiconductor device in which a short channel effect is suppressed by forming a shallow impurity diffusion layer. Is to do.

[0010]

According to the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: forming a gate insulating film on a semiconductor substrate; forming a gate electrode on the gate insulating film; Removing the insulating film on the surface of the impurity diffusion layer formation region to expose the semiconductor substrate in the impurity diffusion layer formation region; and implanting impurity ions into a relatively shallow region of the semiconductor substrate using the gate electrode as a mask And forming a cap film on the exposed semiconductor substrate to prevent outward diffusion, and performing a heat treatment for activating the impurity ions implanted into the semiconductor substrate. I do.

According to the method of manufacturing a semiconductor device, the insulating film on the surface of the impurity diffusion layer forming region in the semiconductor substrate is removed to expose the semiconductor substrate surface, and then the semiconductor substrate is relatively shallow using the gate electrode as a mask. Impurity ions are implanted into the region, and a cap film is formed on the surface of the implanted semiconductor substrate. Therefore, when the semiconductor substrate is subjected to a heat treatment for activating the impurity ions thereafter, the outward diffusion of the impurity ions in the semiconductor substrate by the cap film can be suppressed. As a result, a diffusion layer having a desired impurity concentration and a small depth can be formed in the semiconductor substrate, and the short channel effect can be suppressed.

In the method of manufacturing a semiconductor device according to the present invention, it is preferable that the cap film is any one of a silicon oxide film, a silicon nitride film, a refractory metal silicide film, and a refractory metal compound film. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 are cross-sectional views illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention.

First, as shown in FIG.
Next, a LOCOS oxide film 3 for element isolation is formed. Next, a gate oxide film 5 is formed on the silicon substrate 1 between the LOCOS oxide films 3 by a thermal oxidation method. Next, a polycrystalline silicon film is deposited on the entire surface including the gate oxide film 5, and the polycrystalline silicon film is patterned to form a gate length of 0.13 to 0.18 μm on the gate oxide film 5.
About m gate electrodes 7 are formed. Thereafter, impurity ions 9 are implanted into silicon substrate 1 using gate electrode 7 as a mask, and heat treatment is performed on silicon substrate 1. Thus, the diffusion layer 10 in the extension region is formed on the silicon substrate 1 as shown in FIG. The heat treatment is
It is preferable to use a halogen lamp.

Next, CVD is performed on the entire surface including the gate electrode 7.
(Chemical Vapor Deposition) method to form SiO ₂ film 11
Is deposited.

[0016] Thereafter, as shown in FIG. 3, SiO ₂ film 1
By etching back 1, a sidewall 11 a is formed on the side wall of the gate electrode 7. Further, the oxide film on the surface of the silicon substrate 1 is sufficiently removed. Next, impurity ions 13 are implanted into a shallow region of the silicon substrate 1 with relatively low acceleration energy using the gate electrode 7, the sidewalls 11a and the LOCOS oxide film 3 as a mask.

Next, as shown in FIG.
A cap film 15 for preventing outward diffusion is formed on the entire surface including the surface. As the cap film 15, various films can be used as long as they are dense films that can prevent outward diffusion. Specifically, for example, it is difficult to react with a SiO ₂ film deposited by a CVD method, a silicon nitride film deposited by a CVD method, a refractory metal silicide film such as Ti, Co, W, etc., a TiN film, and a Si such as a WN film. It is possible to use a high melting point metal compound film or the like.

Thereafter, the silicon substrate 1 is annealed at a low temperature for a short time to activate the impurity ions 13, thereby forming a shallow source / drain region diffusion layer 14 on the silicon substrate 1. Next, the cap film 15 is removed (not shown). However, it is not removed if it is not necessary.

According to the above embodiment, the silicon substrate 1
After the oxide film on the surface is removed to expose the surface of the silicon substrate, as shown in FIG. 3, impurity ions are added to the shallow region of the silicon substrate 1 with relatively low acceleration energy using the gate electrode 7 and the sidewall 11a as a mask. 13 is implanted, and a cap film 15 shown in FIG. 4 is formed on the surface of the implanted silicon substrate 1. Therefore, when the silicon substrate 1 is subsequently annealed at a low temperature for a short time, it is possible to suppress the impurity ions 13 in the silicon substrate from being outwardly diffused (Out Diffusion) by the cap film 15. As a result, the diffusion layer 14 having a desired impurity concentration and a small depth can be formed on the silicon substrate 1, and the short channel effect can be suppressed. Therefore, a fine and high drive capability MOS
An FET can be manufactured.

The present invention is not limited to the above embodiment, but can be implemented with various modifications. For example,
Specific conditions such as the above ion implantation and heat treatment can be appropriately changed.

[0021]

As described above, according to the present invention, after the insulating film on the surface of the impurity diffusion layer forming region in the semiconductor substrate is removed to expose the surface of the semiconductor substrate, the semiconductor substrate is exposed using the gate electrode as a mask. Impurity ions are implanted into a relatively shallow region, and a cap film is formed on the surface of the implanted semiconductor substrate. Therefore, an impurity diffusion layer having a small depth can be formed, and a method for manufacturing a semiconductor device in which a short channel effect is suppressed can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the present invention, showing a step subsequent to FIG. 1;

FIG. 3 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the present invention, showing a step subsequent to FIG. 2;

FIG. 4 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the present invention, which shows the step subsequent to FIG. 3;

FIG. 5 is a cross-sectional view for explaining a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

1 ... silicon substrate 3 ... LOCOS oxide film 5 ... gate oxide film 7 ... gate electrode 9 ... diffusion layer 11 of impurity ions 10 ... extension region ... SiO ₂ film 11a ... side wall 13 ... impurity ions 15 ... cap layer 101 ... silicon substrate 103 LOCOS oxide film 105 Gate oxide film 107 Gate electrode 110 Diffusion layer of extension region 111 a Sidewall 113 Impurity ion

Claims (2)

[Claims] A step of forming a gate insulating film on a semiconductor substrate; a step of forming a gate electrode on the gate insulating film; and removing an insulating film on a surface of an impurity diffusion layer forming region in the semiconductor substrate. Exposing the semiconductor substrate in the impurity diffusion layer formation region, implanting impurity ions into a relatively shallow region of the semiconductor substrate using the gate electrode as a mask, and preventing outward diffusion on the exposed semiconductor substrate. A method for manufacturing a semiconductor device, comprising: a step of forming a cap film; and a step of performing a heat treatment for activating impurity ions implanted into a semiconductor substrate. 2. The semiconductor device according to claim 1, wherein the cap film is any one of a silicon oxide film, a silicon nitride film, a refractory metal silicide film, and a refractory metal compound film. Method.