JPH06196694A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To completely remove a damage layer on a channel region by depositing a polycrystalline silicon film on the surface of a semiconductor substrate, etching the polycrystalline silicon film in the channel region section of a transistor and conducting sacrificing oxidation twice. CONSTITUTION:A nitride film and an oxide film are etched while using a photo- resist as a mask by a photolithographic process and an etching process, the trench of a word line patter is formed, and a polycrystalline silicon film 102 is etched while employing the nitride film as a mask. The polycrystalline silicon film as etching remainder on the surface of a semiconductor substrate and the surface of the semiconductor substrate on a channel region and the sidewall sections of the polycrystalline silicon film 102 are oxidized through an oxidation process, thus shaping an oxide film 107. Even when damage is left in the semiconductor substrate in the channel region by etching the polycrystalline silicon film 102, the damaged section can be removed through the oxidation process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing method, and more particularly to a MOS FET manufacturing method.

[0002]

2. Description of the Related Art As a conventional manufacturing method for a silicide transistor, there is a manufacturing method as shown in FIGS. As shown in FIG. 8A, a step of depositing a polycrystalline silicon film 203 on a semiconductor substrate 201 in which a field oxide film 202 is formed in a predetermined region, and as shown in FIG. Oxide film 2 on silicon film 203
After forming 04, the oxide film 204 and the polycrystalline silicon film 203 in the region to be the channel region of the transistor are formed.
RIE is performed until the silicon substrate is exposed, and as shown in FIG. 8C, a gate oxide film 205 and a gate electrode 206 are formed, and high-concentration impurity ions of the conductivity type opposite to that of the semiconductor substrate are formed. As shown in FIG. 8D, the step of doping by the ion implantation method is performed, and Ti metal is sputtered, and the source / drain regions 208 and the gate electrode 2 are self-aligned by rapid thermal processing (RTA).
06 surface is silicidized to form titanium silicide layer 207
After the formation of Ti, an unreacted Ti is selectively removed. (For example, M. Shimizu et al., Symposium
on VLSI Technology Digest of Tchnical Papers, p11
(1988))

[0003]

[Problems to be Solved by the Invention] Conventional MOS FET
In the manufacturing method, the step of etching the oxide film and the polycrystalline silicon film in the channel region of the transistor by RIE until the silicon substrate is exposed, the RIE damages the silicon substrate, and 8A. Since the portions A and B in FIG. 8D have a steep acute angle shape, there is a problem that electrolytic concentration occurs and the transistor characteristics are deteriorated. Further, since the gate electrode has a T-shape, the gate electrode serves as a mask when the impurity ions are implanted to form the source and drain regions, and an offset occurs. Furthermore, before carrying out the silicidation reaction (T
Since the impurity diffusion layer is formed (before depositing the i metal), it becomes difficult to control the silicidation reaction due to the influence of impurities and the grain of polycrystalline silicon, and TiS becomes difficult to control.
There is a problem that the i2 C54 crystal cannot be stably formed and the resistance becomes high.

[0004]

In order to solve the above problems, in a transistor of a semiconductor device, a source and a drain region exist from above the channel region of the transistor, and the source and the drain region are partially polycrystalline. The insulating film, which is made of a silicon film and separates the side wall of the gate electrode from the polycrystalline silicon film, is formed sufficiently thicker than the gate oxide film, and the gate electrode does not overlap to the upper portion of the polycrystalline silicon film. Characterized by structure.

Alternatively, in a transistor of a semiconductor device, a source region and a drain region exist from above the channel region of the transistor, and the source region and the drain region are made of a polycrystalline silicon film and a refractory metal silicide film. The insulating film separating the gate electrode sidewall from the polycrystalline silicon film and the refractory metal silicide film is formed sufficiently thicker than the gate oxide film, and the gate electrode is
The structure is characterized in that the upper portions of the polycrystalline silicon film and the refractory metal silicide film do not overlap.

As a method of manufacturing the transistor having the above structure, a step of depositing a polycrystalline silicon film on a semiconductor substrate, a step of oxidizing the polycrystalline silicon film in the field region to form a field oxide film, and A step of depositing a first silicon oxide film thereon, a step of depositing a first silicon nitride film thereon, and a step of depositing the first silicon nitride film and the first silicon oxide film in a region to be a word line. Etching away to form a groove in the word line pattern,
A second silicon oxide film is formed on the surface of the silicon substrate in the channel region and on the side wall of the polycrystalline silicon film by a step of etching the polycrystalline silicon film on the active region using the silicon nitride film as a mask and an oxidizing step. A step of depositing a second silicon nitride film, and
Etching back the second silicon oxide film of the silicon nitride film until the second silicon oxide film is exposed, etching away the second silicon oxide film of the channel portion of the transistor, and oxidizing the channel region to a third region. Forming an oxide film, removing the second silicon nitride film by etching, and implanting impurity ions for adjusting the threshold voltage of the transistor through the third silicon oxide film by ion implantation. And then injecting into the channel portion, removing the third oxide film by etching, forming a gate oxide film in the channel region, and forming a first conductive film in the groove of the word line pattern. A step of forming a buried gate electrode, a step of etching away the first silicon nitride film, and an impurity of a conductivity type opposite to that of the semiconductor substrate. It was implanted by ion implantation in said polycrystalline silicon film, the semiconductor substrate and the opposite conductivity type impurity is activated by heat treatment, a source reaching the semiconductor substrate, forming a drain region.

Alternatively, as a method of manufacturing the transistor having the above structure, a step of depositing a polycrystalline silicon film on a semiconductor substrate, a step of oxidizing the polycrystalline silicon film in the field region to form a field oxide film, A step of depositing a first silicon oxide film thereon, a step of depositing a first silicon nitride film thereon, and a step of depositing the first silicon nitride film and the first silicon oxide film in a region to be a word line. Etching away to form a groove of the word line pattern; etching the polycrystalline silicon film on the active region using the silicon nitride film as a mask; and oxidizing the silicon substrate surface in the channel region, and A step of forming a second silicon oxide film on the side wall of the polycrystalline silicon film, a step of depositing a second silicon nitride film, and a step of depositing the second silicon nitride film. A step of etching back the film until the second silicon oxide film is exposed, a step of etching away the second silicon oxide film of the channel portion of the transistor, and a step of oxidizing the channel region to a third oxide film. And a step of etching away the second silicon nitride film, and impurity ions for adjusting the threshold voltage of the transistor are ion-implanted through the third silicon oxide film to pass through the third silicon oxide film. Injecting into the channel portion, etching away the third oxide film, forming a gate oxide film in the channel region, and filling the groove of the word line pattern with a second polycrystalline silicon film. A step of removing the first silicon nitride film by etching, and a step of etching the first polysilicon film using the second polycrystalline silicon film as a mask. Recon the step of the oxide film is etched, the first and second polycrystalline silicon film surface reaches a semiconductor substrate self-aligned manner refractory metal silicide layer is formed a source of drain regions and,
The method includes a step of forming a gate electrode.

As a method of forming a refractory metal silicide layer of the semiconductor device, a step of depositing a refractory metal film on the first and second polycrystalline silicon films, and a first step
A step of reacting the refractory metal film with the polycrystalline silicon film to form a refractory metal silicide film by rapid heat treatment, a step of etching away the unreacted refractory metal film, and a semiconductor by an ion implantation method. A step of injecting an impurity of a conductivity type opposite to that of the substrate into the refractory metal silicide film, a step of changing the refractory metal silicide film into a stable crystal structure by a second rapid heat treatment, and an interlayer insulation on the step. After the film is deposited, heat treatment is performed to activate the impurity of the conductivity type opposite to that of the semiconductor substrate, and the impurity is diffused to the semiconductor substrate in the source and drain regions.

Alternatively, as a method for forming the refractory metal silicide layer, a refractory metal is implanted into the surfaces of the first and second polycrystalline silicon films by an ion implantation method, and the surfaces of the polycrystalline silicon films are made amorphous. And a step of depositing a refractory metal film made of the refractory metal on the polycrystalline silicon film, and the refractory metal and the refractory metal in the polycrystalline silicon film by the first rapid heat treatment. A step of reacting the melting point metal film with silicon atoms in the polycrystalline silicon film to form a refractory metal silicide film; a step of etching away the silicon atoms and the unreacted refractory metal film;
A step of implanting an impurity of a conductivity type opposite to that of the semiconductor substrate by an ion implantation method, and a step of changing the refractory metal silicide film into a stable crystal structure by a second rapid heat treatment,
After depositing an interlayer insulating film on it, heat treatment is performed to activate impurities of the opposite conductivity type to the semiconductor substrate, and
In the source and drain regions, a step of diffusing impurities to the semiconductor substrate is provided.

The refractory metals are Ti, Co, N
i, Zr, V, and Hf.

Alternatively, in the above method of manufacturing a semiconductor device,
It is characterized in that first and second amorphous silicon films are used instead of the first and second polycrystalline silicon films.

[0012]

EXAMPLES The method for manufacturing a semiconductor device of the present invention will be described in detail below with reference to examples.

1 (a)-(c) and 2 (d)-
(E) and FIGS. 3 (f) to (g) and FIGS. 4 (h) to (i).
5 (j) to 5 (k), 6 (l) to 6 (m), and 7 (n) to 7 (o) are sectional views in order of steps of the transistor forming method according to the first embodiment of the present invention. .

First, as shown in FIG. 1A, a film thickness 100 is formed on a semiconductor substrate (P-type semiconductor substrate in this embodiment) 101.
A polycrystalline silicon film 102 having a thickness of about nm is deposited.

Next, as shown in FIG. 1B, the polycrystalline silicon film 102 is selectively oxidized by a known method to form a field oxide film 103, and then an oxide film 104 of about 40 nm is deposited. To do.

Next, as shown in FIG. 1 (c), about 500
A nitride film 105 having a thickness of about nm is deposited.

Next, as shown in FIG. 2D, the nitride film 105 and the oxide film 10 are formed by a photolithography process and an etching process using the photoresist as a mask.
After etching 4 to form a groove of the word line pattern, the polycrystalline silicon film 102 is etched using the nitride film 105 as a mask. Here, for the etching of the polycrystalline silicon film 102, it is preferable that the etching condition is such that about 10 nm is left so as not to damage the semiconductor substrate as much as possible.

Next, as shown in FIG. 2 (e), the polycrystalline silicon film remaining after etching on the semiconductor substrate surface and the semiconductor substrate surface on the channel region and the sidewall portion of the polycrystalline silicon film 102 are oxidized by an oxidation process. Then, an oxide film 107 having a thickness of about 50 nm is formed. By this oxidation step, even if the semiconductor substrate in the channel region remains damaged by the etching of the polycrystalline silicon film 102, it can be removed. Next, as shown in FIG.
The nitride film 108 is deposited to a certain degree. Next, as shown in FIG. 3G, the nitride film 108,
The oxide film 107 is sequentially etched. Here, the etch back is preferably performed under such etching conditions that the oxide film 107 on the channel region is left by about 10 nm so that the semiconductor substrate is not damaged.

Next, as shown in FIG. 4H, the oxide film remaining on the channel region is removed by etching with a hydrofluoric acid solution.

Next, as shown in FIG. 4I, after about 10 nm is oxidized in an oxidizing atmosphere to form an oxide film 109, an impurity for adjusting the threshold voltage of the transistor is implanted.

Next, as shown in FIG. 5 (j), the groove 106
After the nitride film 108 on the side wall is removed by etching using phosphoric acid-based wet etching (this step allows the nitride film 10 to be removed).
5 is slightly etched, and the groove 106 is slightly widened),
The oxide film 109 is removed by etching with a hydrofluoric acid solution. At this time, the oxide film 10 on the sidewall of the polycrystalline silicon 102 is formed.
7 is also slightly etched to have a film thickness of about 30 nm.

Next, as shown in FIG. 5K, the polycrystalline silicon film 111 is buried in the groove 106 by a known method.

Next, as shown in FIG. 6 (l), the nitride film 1
After removing 05 by phosphoric acid-based wet etching, the oxide film 104 is etched by RIE using the polycrystalline silicon film 111 as a mask until the surface of the polycrystalline silicon film 102 is exposed.

Next, as shown in FIG. 6 (m), a refractory metal film (a titanium film of about 50 nm in this embodiment) is deposited.

Next, as shown in FIG. 7 (n), the first R
TA treatment is performed, for example, in a nitrogen atmosphere at 625 ° C. for about 20 seconds to form a metastable titanium silicide layer 113, and unreacted titanium metal is removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide solution. 95% of the dose amount of impurity ions (arsenic ions in this embodiment) of the conductivity type opposite to that of the substrate
The above is the energy that is injected into the titanium silicide film 113. For example, in the present embodiment, the energy is 35 Ke.
After implanting a dose of about 5E15 / cm 2 into the titanium silicide film 113 with an implantation energy of about v, a second RTA treatment is performed, for example, in a nitrogen atmosphere at 90 ° C.
The titanium silicide film 113 is formed at 0 ° C. for about 20 seconds.
To a stable, TiSi2C54 crystal structure.
Next, as shown in FIG. 7 (o), after depositing the interlayer insulating film 114, a source / drain region 115 reaching the semiconductor substrate 101 is formed by heat treatment at 900 ° C. for about 15 minutes. Sufficiently activates the As ions of.

After that, a desired semiconductor device is obtained through known steps.

In the transistor formed in this embodiment, the polycrystalline silicon film on the channel region is etched and then sacrificial oxidation is performed twice. Therefore, the layer damaged by the etching on the surface of the semiconductor substrate must be removed. You can Further, since the n + diffusion layer region is formed after forming the silicide layer, the influence of As ions on silicidation on the n + diffusion layer region is eliminated, and it is possible to form a silicide layer having a very low resistance. became. Further, it is possible to suppress the diffusion of titanium metal into the semiconductor substrate as much as possible, and since the Rp of As ion implantation for forming the n + diffusion layer region is suppressed in the titanium silicide layer, the semiconductor substrate is damaged by the ion implantation. By not receiving this, it has become possible to reduce the leak current from the source / drain regions to the semiconductor substrate. Further, since the impurities are diffused from the silicide layer formed above the channel portion, it is possible to form a very shallow junction and suppress the short channel effect of the transistor. Further, unlike the conventional example, the gate electrode does not have a T-shape, so that an offset due to the gate electrode as shown in FIG.

(Embodiment 2) The method for forming a semiconductor device of the present invention is not limited to the first embodiment.

As shown in FIG. 6L, after removing the nitride film 105 by phosphoric acid wet etching, the oxide film 104 is exposed by using the polycrystalline silicon film 111 as a mask until the surface of the polycrystalline silicon film 102 is exposed. RIE
After the steps up to etching are carried out in the same manner as in the first embodiment, 5E1 impurity ions (for example, arsenic ions) of the opposite conductivity type to the substrate are implanted with an implantation energy of about 35 Kev.
The polycrystalline silicon film 10 has a dose of about 5 / cm2.
90, after implanting in 2 and 111 and depositing an interlayer insulating film.
The source / drain regions 115 reaching the semiconductor substrate 101 are formed by heat treatment at 0 ° C. for about 15 minutes, and the As ions in the gate electrode 111 are sufficiently activated. After that, a desired semiconductor device is obtained through known steps.

(Embodiment 3) The method of forming a silicide layer according to the present invention is not limited to the first embodiment. As the silicidation of the polycrystalline silicon film, the polycrystalline silicon film 10
Refractory metal ions, such as Ti ions, are implanted into 2, 111 by an ion implantation method to form a polycrystalline silicon film 102,
111 Amorphize the surface. Next, a refractory metal film made of the same metal as the refractory metal, for example, a Ti film in this embodiment is deposited. Next, a first RTA process is performed, for example, in a nitrogen atmosphere at 625 ° C. for about 20 seconds to react Ti in the polycrystalline silicon films 204 and 211 with the Ti film and silicon in the polycrystalline silicon film, A stable titanium silicide layer 113 is formed, and unreacted titanium metal is removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide solution. After that,
A desired transistor element is formed through the same steps as in the first embodiment.

An amorphous silicon film may be used in place of the polycrystalline silicon films 102 and 111 of the first to third embodiments of the present invention. When an amorphous silicon film is used, there is an advantage that a silicidation reaction occurs uniformly because grains unlike the polycrystalline silicon film do not exist.

The refractory metal material for forming the silicide layer of the present invention is not limited to titanium metal. C
O, Ni, Zr, V, Hf metals may be used.

[0033]

As is clear from the above, the present invention is
After depositing a polycrystalline silicon film on the surface of the semiconductor substrate and etching the polycrystalline silicon film in the channel region of the transistor, sacrificial oxidation is performed twice, so that the damaged layer on the channel region can be completely removed. Become.

Further, since the polycrystalline silicon film is provided on the surface of the semiconductor substrate for silicidation, the diffusion of titanium metal into the semiconductor substrate can be suppressed as much as possible.
Further, since the ion implantation is performed so that Rp is contained in the titanium silicide layer, generation of defects in the semiconductor substrate is suppressed, and further, electrolytic concentration such as A and B in FIG. 8D occurs. Since the oxide film is not thickly formed at the easily sharp corners due to the sacrificial oxidation, the leak current can be reduced.

Further, since the n + diffusion layer region can be formed after the formation of the silicide layer, the influence of As ions on silicidation on the n + diffusion layer region is eliminated, and complete Ti
A Si2C54 crystal structure can be formed, and a very low resistance silicide layer can be formed.

Further, since the sacrificial oxidation after etching the polycrystalline silicon film in the channel region of the transistor is performed before the ion implantation, and because the impurities are diffused from the silicide layer formed above the channel. It becomes possible to form a very shallow junction and suppress the short channel effect of the transistor.

Further, unlike the conventional example, the gate electrode does not have a T-shape, and an offset due to the gate electrode does not occur at the time of implanting impurity ions for forming the source and drain regions, so that the transistor speed can be increased. Becomes

[Brief description of drawings]

1A to 1C are cross-sectional views in order of the processes of an embodiment of the present invention.
It is (c).

2A to 2D are cross-sectional views in order of the processes of an embodiment of the present invention.
(E).

3A to 3C are cross-sectional views in order of the steps of the embodiment of the present invention (f).
(G).

4A to 4C are cross-sectional views in order of the processes of an embodiment of the present invention.
(I).

5A to 5C are cross-sectional views in order of the processes of an embodiment of the present invention (j).
(K).

6A to 6C are cross-sectional views in order of the processes of an embodiment of the present invention (l) to
(M).

7A to 7C are cross-sectional views in order of the processes of an embodiment of the present invention (n).
(O).

FIG. 8 is sectional views (a) to (d) in order of stroke in a conventional example.

[Explanation of symbols]

 101, 201 Semiconductor substrate 202 Field oxide film 102, 203 Polycrystalline silicon film 103 Field oxide film 104, 204 Oxide film 105 Nitride film 106 Groove 107 Oxide film 108 Nitride film 109 Oxide film 110, 205 Gate oxide film 206 Gate electrode 111 Multi Crystal silicon film 112, refractory metal film (Ti metal film) 113, 207 Titanium silicide film 114 Inter-layer insulating film 115, 208 Source / drain regions

Claims (8)

[Claims] 1. A source / drain region is present from above a channel region of a transistor, and the source / drain region is partially formed of a polycrystalline silicon film, and an insulating film for separating a gate electrode sidewall from the polycrystalline silicon film. Is formed to be sufficiently thicker than the gate oxide film, and the gate electrode does not overlap up to the upper portion of the polycrystalline silicon film. 2. A source / drain region is present from above a channel region of a transistor, and the source / drain region is partially composed of a polycrystalline silicon film and a refractory metal silicide film, and has a gate electrode sidewall and the polycrystalline silicon film. The insulating film for separating the film and the refractory metal silicide film is formed sufficiently thicker than the gate oxide film, and the gate electrode does not overlap up to the upper portions of the polycrystalline silicon film and the refractory metal silicide film. A semiconductor device characterized by this. 3. A step of forming a transistor in a semiconductor device, a step of depositing a polycrystalline silicon film on a semiconductor substrate, a step of oxidizing the polycrystalline silicon film in a field region to form a field oxide film, A step of depositing a first silicon oxide film thereon, a step of depositing a first silicon nitride film thereon, and the first silicon nitride film and the first silicon oxide film in a region to be a word line. Are removed by etching to form a groove of a word line pattern, a step of etching the polycrystalline silicon film on the active region using the silicon nitride film as a mask, and an oxidation step.
Forming a second silicon oxide film on the surface of the silicon substrate in the channel region and on the side wall of the polycrystalline silicon film; depositing a second silicon nitride film; and adding the second silicon nitride film to the second silicon nitride film. Etching back until the silicon oxide film is exposed, a step of etching away the second silicon oxide film in the channel portion of the transistor, and a step of forming a third oxide film in the channel region by an oxidation step. A step of etching away the second silicon nitride film, and implanting impurity ions for adjusting the threshold voltage of the transistor into the channel portion through the third silicon oxide film by an ion implantation method. A step of etching away the third oxide film, a step of forming a gate oxide film in the channel region, and the word A step of burying a first conductive film in a groove of a pattern to form a gate electrode, a step of etching and removing the first silicon nitride film, and an impurity of a conductivity type opposite to that of a semiconductor substrate in the polycrystalline silicon film. A method of manufacturing a semiconductor device, which comprises a step of implanting by an ion implantation method and activating an impurity of a conductivity type opposite to that of the semiconductor substrate by heat treatment to form source and drain regions reaching the semiconductor substrate. 4. A process of forming a transistor of a semiconductor device, a process of depositing a polycrystalline silicon film on a semiconductor substrate, a process of oxidizing the polycrystalline silicon film in a field region to form a field oxide film, A step of depositing a first silicon oxide film thereon, a step of depositing a first silicon nitride film thereon, and the first silicon nitride film and the first silicon oxide film in a region to be a word line. Are removed by etching to form a groove of a word line pattern, a step of etching the polycrystalline silicon film on the active region using the silicon nitride film as a mask, and an oxidation step.
Forming a second silicon oxide film on the surface of the silicon substrate in the channel region and on the side wall of the polycrystalline silicon film; depositing a second silicon nitride film; and adding the second silicon nitride film to the second silicon nitride film. Etching back until the silicon oxide film is exposed, a step of etching away the second silicon oxide film in the channel portion of the transistor, and a step of forming a third oxide film in the channel region by an oxidation step. A step of etching away the second silicon nitride film, and implanting impurity ions for adjusting the threshold voltage of the transistor into the channel portion through the third silicon oxide film by an ion implantation method. A step of etching away the third oxide film, a step of forming a gate oxide film in the channel region, and the word A step of embedding a second polycrystalline silicon film in the groove of the pattern, a step of etching and removing the first silicon nitride film, and a step of etching the first silicon oxide film using the second polycrystalline silicon film as a mask And a step of forming a source / drain region and a gate electrode reaching the semiconductor substrate in which the refractory metal silicide layer is formed on the surfaces of the first and second polycrystalline silicon films in a self-aligning manner. A method for manufacturing a characteristic semiconductor device. 5. The method for forming a refractory metal silicide layer of a semiconductor device according to claim 4 is the same as the first method described above.
And a step of depositing a refractory metal film on the second polycrystalline silicon film, and reacting the refractory metal film with the polycrystalline silicon film by the first rapid heat treatment to form a refractory metal silicide film. A step of removing the unreacted refractory metal film by etching, a step of implanting an impurity of a conductivity type opposite to that of the semiconductor substrate into the refractory metal silicide film by an ion implantation method, and a second rapid heat treatment The step of changing the refractory metal silicide film into a stable crystal structure by the method, and after depositing an interlayer insulating film thereon, heat treatment is performed to activate impurities of a conductivity type opposite to that of the semiconductor substrate. A method of manufacturing a semiconductor device, comprising: diffusing impurities in a drain region to a semiconductor substrate. 6. The method for forming a refractory metal silicide layer of a semiconductor device according to claim 4, wherein refractory metal is implanted into the surfaces of the first and second polycrystalline silicon films by an ion implantation method. Then, the step of amorphizing the surface of the polycrystalline silicon film, the step of depositing a refractory metal film made of the refractory metal on the polycrystalline silicon film, and the step of polycrystallizing by the first rapid heat treatment. A step of reacting the refractory metal in the silicon film and the refractory metal film with silicon atoms in the polycrystalline silicon film to form a refractory metal silicide film; and the refractory metal film unreacted with silicon atoms Of the refractory metal silicide film into a stable crystal structure by a step of etching and removing, a step of implanting an impurity of a conductivity type opposite to that of the semiconductor substrate by an ion implantation method, and a second rapid heat treatment. And a step of depositing an interlayer insulating film on the step and activating heat treatment to activate an impurity of a conductivity type opposite to that of the semiconductor substrate and diffusing the impurity to the semiconductor substrate in the source / drain region. A method of manufacturing a semiconductor device, comprising: 7. A method of manufacturing a semiconductor device, wherein the refractory metal according to claims 5 and 6 is Ti, Co, Ni, Zr, V or Hf. 8. The method of manufacturing a semiconductor device according to claim 5, wherein first and second amorphous silicon films are used instead of the first and second polycrystalline silicon films. A method for manufacturing a semiconductor device, which is characterized by being used.