JPH10144624A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for fabricating a semiconductor device having a silicide layer having an excellent heat resistance and low resistance. SOLUTION: A titanium film 6 is formed on a semiconductor substrate 1 having a gate electrode 4 formed thereon. Formed on the titanium film 6 is a titanium nitride film 7 at a temperature of 300 to 500 deg.C. The titanium film 6, polycrystalline silicon 4 and semiconductor substrate 1 are reacted with each other to form a titanium silicide layer 8 in a diffusion layer formation region DF on the substrate 1. Thereby a uniform TiN/Ti interface can be maintained during a high-temperature heat treatment for silicification and thus there can be formed a silicide layer which is low in resistance without causing any aggregation at a high temperaturc.

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 having a silicide layer.

[0002]

2. Description of the Related Art In order to increase the degree of integration of LSIs, it is necessary to miniaturize elements. This miniaturization requires not only reducing the dimension in the planar direction but also reducing the dimension in the depth direction. In order to achieve this, it is necessary to reduce the junction depth of the impurity diffusion layers in the source / drain regions. However, when the thickness of the diffusion layers in the semiconductor substrate is reduced, the resistance of the impurity diffusion layers increases, There is a problem that the operation speed of the semiconductor device is reduced.

To cope with this, a structure in which a low-resistance silicide layer is formed on the surface of the impurity diffusion layer to reduce the source / drain resistance is effective. As a method of forming the silicide layer, a method of depositing a metal film on the surface of a silicon substrate and then subjecting the metal film to heat treatment to react the silicon with the metal to silicide the source / drain regions has been used. I have been.

In particular, in recent years, a so-called salicide process has been performed in which a polycrystalline silicon film used for a gate electrode is also silicided to reduce wiring resistance. 30a-Z
H-4 describes such a method. This salicide process will be described with reference to FIG.

First, an insulating film 2 for element isolation is formed on a semiconductor substrate 1.
After forming the thermal oxide film 3, a polycrystalline silicon film 4 is deposited, and the polycrystalline silicon film 4 is processed into a gate electrode shape (FIG. 1a). Thereafter, a gate side wall 5 is formed using an oxide film (FIG. 1B).

Thereafter, the entire surface of the semiconductor substrate 1 is sputtered to a degree of vacuum of about 1 to 10 mTorr in an Ar atmosphere.
The titanium film 6 is deposited under the condition that the temperature of the semiconductor substrate 1 is 200 ° C. or less. Next, the temperature of the semiconductor substrate 1 is not particularly changed, the degree of vacuum is about 1 to 10 mTorr, N ₂ is introduced into a sputtering chamber (not shown), and T ₂ is formed by a reactive sputtering method.
An iN film 7 is deposited (FIG. 1c).

[0007] Then, at atmospheric pressure in an N ₂ atmosphere,
Heat treatment is performed at 900 ° C. for 10 to 60 seconds to form a TiSi ₂ silicide layer 8 on the surfaces of the semiconductor substrate 1 and the polycrystalline silicon 4 (FIG. D).

Next, the unreacted TiN and Ti films are removed using a mixed solution of sulfuric acid and hydrogen peroxide or a mixed solution of hydrochloric acid and hydrogen peroxide. In the above conventional method, in order to avoid the problem that silicide aggregates during high-temperature treatment and resistance increases due to thinning of the silicide layer accompanying miniaturization,
By depositing the TiN film 7 as a cap film and performing a heat treatment for forming the TiSi ₂ silicide layer 8, stress is applied to the silicide layer 8 to be formed, and aggregation of silicide is suppressed.

[0009]

However, in the above method, when the TiN film 7 is formed in the step of FIG.
In the case of using the so-called reactive sputtering method, when the temperature of the semiconductor substrate 1 is set to a high temperature of 700 to 900 ° C. in order to form the silicide layer 8 constituting the salicide structure, the silicide also aggregates and the resistance increases. The problem arises.

This is because unreacted nitrogen remaining at the interface between the TiN film 7 and the Ti film 6 reacts with the underlying Ti film 6 during the heat treatment for forming the silicide layer 8 and newly forms TiN.
A film is formed, and the TiN film and the TiSi _{2 of the} silicide layer 8 are formed.
Is mixed, the flatness of the interface between the TiN film 7 and the silicide layer 8 is deteriorated, and the TiN film 7 does not become a uniform cap layer for preventing aggregation.

As a countermeasure, the use of a TiN compound target eliminates the need for introducing N ₂ gas.
There has been proposed a compound sputtering method that does not cause unreacted nitrogen to remain. However, this method has a problem that a new TiN target must be prepared and a dedicated sputtering chamber must be provided.

In view of the above problems, an object of the present invention is to make it possible to easily form a silicide layer having excellent heat resistance and low resistance while using a reactive sputtering method.

[0013]

A method of manufacturing a semiconductor device according to the present invention comprises a first step of forming a titanium film on a semiconductor substrate having a gate electrode formed thereon, and a step of forming a titanium nitride film on the titanium film. In the second step of forming, at a predetermined temperature higher than the temperature when forming the titanium film in the first step, and at a predetermined temperature at which the titanium film and the titanium nitride film do not react with each other, A second step of forming a titanium nitride film; and, after the second step, a third step of forming a titanium silicide layer on the gate electrode and in a diffusion layer formation region on the semiconductor substrate. Features.

Another feature of the present invention is that:
A first step of forming a titanium film on the semiconductor substrate on which the gate electrode is formed, a second step of forming a titanium nitride film on the titanium film, and after the second step, the second step A predetermined negative pressure than the pressure at which the titanium nitride film is formed in the step, and a temperature higher than the temperature at which the titanium nitride film is formed in the second step; and A third step of heat-treating the semiconductor substrate at a predetermined temperature at which the titanium nitride film does not react, and after the third step, titanium is formed on the gate electrode and in a diffusion layer formation region on the semiconductor substrate. And a fourth step of forming a silicide layer.

According to another feature of the present invention, in the method of manufacturing a semiconductor device according to any one of claims 1 and 2, the predetermined temperature is 300 to 50.
It is characterized by being at any temperature in the range of 0 ° C.

Another feature of the present invention is that in the method of manufacturing a semiconductor device according to claim 2,
The predetermined atmospheric pressure is 1E to 5 Torr or less.

Another feature of the present invention is that in the method of manufacturing a semiconductor device according to claim 1,
Before the first step or after the third step, a diffusion layer is formed in the diffusion layer formation region.

Another feature of the present invention is that in the method of manufacturing a semiconductor device according to claim 2,
Before the first step or after the third step, a diffusion layer is formed in the diffusion layer formation region.

[0019]

According to the present invention, when a TiN film is formed by reactive sputtering, the substrate temperature is raised to increase T.sub.T.
Unreacted nitrogen on the surface of the i-film is eliminated, and a uniform TiN / Ti interface can be maintained during high-temperature heat treatment for silicidation. Thus, a silicide layer having low resistance without aggregation even at high temperatures can be obtained. it can.

According to another feature of the present invention, TiN
After depositing the film, by performing a low-temperature heat treatment in a vacuum, the unreacted N remaining at the TiN / Ti interface is diffused out and removed, thereby preventing the deterioration of the interface uniformity during the high-temperature heat treatment. This makes it possible to obtain a silicide layer having low resistance without aggregation even at a high temperature.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a method for manufacturing a semiconductor device according to the present invention will be described with reference to FIG.
First, as shown in FIG. 1A, an oxide film 2 for element isolation is formed on a semiconductor substrate 1. Then, a thickness of 5 to 20 nm
Oxide film 3 is formed by a thermal oxidation method.
By the known chemical vapor deposition method (CVD method),
A polycrystalline silicon film 4 having a thickness of 00 to 300 nm is deposited.

Next, as shown in FIG. 1B, the polycrystalline silicon film 4 is processed into a gate electrode shape by a known patterning technique.

Next, a thickness of 100 to 100 is obtained by a known CVD method.
An oxide film 5 having a thickness of 300 nm is deposited, and the entire surface of the semiconductor substrate 1 is etched back by a known etching technique, thereby processing the oxide film 5 into a shape of a side wall of the gate electrode.

Next, as shown in FIG. 1C, a natural oxide film (not shown) on the surface of the semiconductor substrate 1 and the polycrystalline silicon film 4 is removed with a dilute hydrofluoric acid-based solution, and then the semiconductor is formed by sputtering. Ti film 6 which is a refractory metal on the surface of substrate 1
Is deposited. As for the sputtering conditions, the degree of vacuum is 1 to 10 mTo.
The temperature is about rr, the Ar atmosphere, the substrate temperature is 200 ° C. or less, and the film thickness is about 20 to 100 nm.

Next, the semiconductor substrate 1 is heated at 300 to 500 ° C.
To about 1 to 10 mTorr, N
₂ is introduced into a sputtering chamber (not shown), and a TiN film 7 which is a refractory metal nitride film is formed by a reactive sputtering method.
Deposit about 00 nm.

Thereafter, as shown in FIG. 1 (d), at 700 to 900 ° C. and 10 to 60 seconds in an atmosphere and N ₂ atmosphere.
c is performed, and the diffusion layer formation region DF of the semiconductor substrate 1 is formed.
Then, a TiSi silicide layer 8 is formed on the surface of the polycrystalline silicon 4. Next, unreacted TiN and Ti films are removed using a mixed solution of sulfuric acid and hydrogen peroxide or a mixed solution of hydrochloric acid and hydrogen peroxide.

In the first embodiment, when the TiN film 7 is formed, unreacted nitrogen on the surface of the Ti film 6 is eliminated by heating the semiconductor substrate 1 to about 300 to 500.degree. Thus, a silicide layer having low resistance without aggregation even at a high temperature can be obtained, and the degree of integration can be improved without lowering the operation speed of the semiconductor device.

Next, a second embodiment of the method for manufacturing a semiconductor device according to the present invention will be described below. The steps up to the step of depositing the Ti film 6 are performed in the same manner as in the first embodiment. Next, while maintaining the degree of vacuum at about 1 to 10 mTorr, N ₂ was introduced into the sputtering chamber, and a TiN film 7 as a refractory metal nitride film was deposited to a thickness of about 20 to 100 nm by a reactive sputtering method. ).

Thereafter, as shown in FIG. 1D, the supply of gas is stopped without breaking the vacuum, and a heat treatment of about 300 to 500 ° C. and about 30 to 300 SEC is performed in a vacuum of 1E-5 Torr or less. By this heat treatment in vacuum, the TiN film 7
Unreacted N remaining at the interface of the / Ti film 6 is diffused outward and removed.

Next, at atmospheric pressure and N ₂ atmosphere, 700
Heat treatment is performed at 900 ° C. for 10 to 60 seconds to form a TiSi silicide layer 8 on the surface of the diffusion layer formation region DF of the semiconductor substrate 1 and the polycrystalline silicon 4.

In the first and second embodiments, after the gate electrode 4 is formed and before the Ti film 6 is formed,
A source / drain region is formed in the diffusion layer formation region DF by a known ion implantation method 2, or a source / drain region is formed in the diffusion layer formation region DF after the silicide layer 8 is formed.

[0032]

According to the present invention, as described above, according to the present invention, when a TiN film is formed by reactive sputtering, unreacted nitrogen on the surface of the Ti film is eliminated by increasing the substrate temperature. And a uniform TiN / Ti interface can be maintained during a high-temperature heat treatment for silicidation, and a silicide layer having low resistance without aggregation even at a high temperature can be obtained. Thus, the degree of integration can be improved without lowering the operation speed of the semiconductor device.

According to another feature of the present invention, TiN
After depositing the film, by performing a low-temperature heat treatment in a vacuum, the unreacted N remaining at the TiN / Ti interface is diffused out and removed, thereby preventing the deterioration of the interface uniformity during the high-temperature heat treatment. This makes it possible to obtain a silicide layer having low resistance without aggregation even at a high temperature.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining a method for manufacturing a semiconductor device according to the present invention;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor substrate 2 thermal oxide film for element isolation 3 thermal oxide film 4 polycrystalline silicon film (gate electrode) 5 oxide film 6 refractory metal film 7 refractory metal nitride film 8 silicide layer DF diffusion layer formation region

Claims (6)

[Claims] A first step of forming a titanium film on a semiconductor substrate on which a gate electrode is formed; and a step of forming a titanium nitride film on the titanium film, wherein the titanium in the first step is A second step of forming the titanium nitride film at a predetermined temperature higher than the temperature at which the film is formed and at which the titanium film and the titanium nitride film do not react with each other, after the second step, A third step of forming a titanium silicide layer on the gate electrode and in a diffusion layer formation region on the semiconductor substrate. 2. A first step of forming a titanium film on a semiconductor substrate on which a gate electrode is formed, a second step of forming a titanium nitride film on the titanium film, and after the second step, At a predetermined negative pressure than the pressure at the time of forming the titanium nitride film in the second step,
And a third step of heat-treating the semiconductor substrate at a predetermined temperature higher than the temperature at which the titanium nitride film is formed in the second step and at which the titanium film and the titanium nitride film do not react. And a fourth step of, after the third step, forming a titanium silicide layer on the gate electrode and in a diffusion layer formation region on the semiconductor substrate. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the predetermined temperature is any temperature in a range of 300 to 500 ° C. Device manufacturing method. 4. The method of manufacturing a semiconductor device according to claim 2, wherein the predetermined atmospheric pressure is 1E to 5 Torr or less. 5. The semiconductor device manufacturing method according to claim 1, wherein a diffusion layer is formed in the diffusion layer formation region before the first step or after the third step. Device manufacturing method. 6. The semiconductor device manufacturing method according to claim 2, wherein a diffusion layer is formed in the diffusion layer formation region before the first step or after the third step. Device manufacturing method.