JPH06196496A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To restrain a short channel effect in a transistor so as to enhance it in operational speed by a method wherein the side walls of a gate electrode and a word line and the upside of the word line are covered with an insulating film, and a source region and a drain region are buried in a region sandwiched between the word line and the gate electrode so as to reach a semiconductor substrate. CONSTITUTION:A word line 209 wherein a gate electrode 208 is buried is formed on an active region, an oxide film is deposited, and then a side wall oxide film 210 is provided onto the side wall of the word line 209 and the gate electrode 208. Then, a polycrystalline silicon film 211 is buried in a region sandwiched between the word line 209 and the gate electrode 208. Next, a quasi-stable titanium silicide layer 212 is formed and turned into a stable TiSi2-C 54 crystal structure. Then, an interlayer insulating film 213 is deposited, then a source.drain region 214 is formed so as to reach a semiconductor substrate 201, and As ions in the gate electrode are activated enough. Lastly, a contact hole is bored, an upper wiring is provided, and thus a semiconductor device can be obtained.

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. 5A, a step of depositing a polycrystalline silicon film 303 on a semiconductor substrate 301 having a field oxide film 302 formed in a predetermined region, and as shown in FIG. Oxide film 30 on silicon film 303
4 is formed, the oxide film 304 and the polycrystalline silicon film 303 in the region to be the channel region of the transistor are etched by RIE until the silicon substrate is exposed, and as shown in FIG. Oxide film 3
05, the step of forming the gate electrode 306, doping the high-concentration impurity ions of the conductivity type opposite to that of the semiconductor substrate by the ion implantation method, and sputtering Ti metal as shown in FIG. The source / drain region 308 and the gate electrode 30 are self-aligned by (RTA).
After the titanium silicide layer 307 is formed by siliciding the surface, the unreacted Ti is selectively removed. (For example, M. Shimizu et al., Symposium on
VLSI Technology Digest of Tchnical Papers, p11 (1
988))

[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 Since the portions A and B in FIG. 5D have a steep acute angle shape, there is a problem that electrolytic concentration occurs and the transistor characteristics are deteriorated. Further, since the impurity diffusion layer is formed before performing the silicidation reaction (before depositing the Ti metal), it is difficult to control the silicidation reaction due to the influence of impurities and the grain of polycrystalline silicon. There is a problem that the TiSi2 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 gate electrode is buried in an active region surrounded by an element isolation region via a gate insulating film, A word line is present on the gate electrode and the element isolation region, and a sidewall portion of the gate electrode and the word line and an upper portion of the word line are covered with an insulating film, and a region between the word line and the gate electrode is provided. Is characterized in that the source and drain regions reaching the semiconductor substrate are buried, and a manufacturing method thereof is the step of forming an element isolation region on the semiconductor substrate, the step of forming a gate insulating film, and the element A step of embedding a first polycrystalline silicon film in the active region surrounded by the isolation region via the gate insulating film, and selectively forming a first refractory metal only on the surface of the first polycrystalline silicon film. A step of forming a silicide film, a step of sequentially depositing a conductive film and a first insulating film, a step of depositing the first polycrystalline silicon film, a first refractory metal silicide film, a conductive film, Patterning the insulating film into a word line pattern to form a gate electrode in the active region surrounded by the element isolation region; forming a second insulating film on the gate electrode and the word line sidewall; A step of embedding a second polycrystalline silicon film reaching the active region in a region sandwiched by a line and a gate electrode, and patterning the second polycrystalline silicon film to prevent a short circuit with an adjacent active region. However, the second refractory metal silicide film is formed in a self-aligning manner only on the surface of the second polycrystalline silicon film by the step of separating on the element isolation region, and impurities of the conductivity type opposite to that of the semiconductor substrate are formed. By The method of forming source and drain regions of a transistor of the semiconductor device comprises depositing a refractory metal film on the upper surface of the second polycrystalline silicon film. And a step of reacting the refractory metal film with the second polycrystalline silicon film by a first rapid heat treatment to form a refractory metal silicide film, and removing the unreacted refractory metal film by etching. And a step of implanting an impurity of a conductivity type opposite to that of the semiconductor substrate into the refractory metal film by an ion implantation method, and a second rapid heat treatment to change the refractory metal silicide film into a stable crystal structure. After the process and the deposition of the interlayer insulating film on the process, heat treatment is performed to activate the impurity of the conductivity type opposite to that of the semiconductor substrate and to diffuse the impurity to the semiconductor substrate. It is characterized by including a step of Alternatively, a step of injecting a refractory metal into the surface of the second polycrystalline silicon film by an ion implantation method to amorphize the surface of the second polycrystalline silicon film, and an upper portion of the second polycrystalline silicon film And a step of depositing a refractory metal film made of the refractory metal, and a step of first rapid heat treatment to remove the refractory metal in the polycrystal silicon film and the refractory metal film from the second polycrystal silicon. A step of reacting with silicon atoms in the film to form a refractory metal silicide film; a step of etching away the refractory metal film that has not reacted with silicon atoms; and an impurity of a conductivity type opposite to that of the semiconductor substrate by an ion implantation method. An implanting step, a step of changing the refractory metal silicide film into a stable crystal structure by a second rapid heat treatment, and an interlayer insulating film deposited thereon, and then a heat treatment is performed to form the semiconductor substrate. The conductivity type of impurities to test the activating includes the step of diffusing impurities to the semiconductor substrate.

Alternatively, in order to solve the above problems, in a method of manufacturing a transistor of a semiconductor device, a step of forming an element isolation region on a semiconductor substrate, a step of forming a gate insulating film, and A step of embedding a first amorphous silicon film in the surrounded active region via the gate insulating film, and selectively forming a first refractory metal silicide film only on the surface of the first amorphous silicon film And a step of sequentially depositing a conductive film and a first insulating film, the first amorphous silicon film, the first refractory metal silicide film, the conductive film, and the first insulating film. Patterning the film into a word line pattern to form a gate electrode in the active region surrounded by the element isolation region; forming a second insulating film on the gate electrode and the word line sidewall; And sandwiched between the gate electrodes The step of burying the second amorphous silicon film reaching the above-mentioned active region in the open region and the patterning of the second amorphous silicon film in order to prevent a short circuit with the adjacent active region, A second refractory metal silicide film is formed in a self-aligning manner only on the surface of the second amorphous silicon film by the above separation step, and the semiconductor substrate is formed by impurities of a conductivity type opposite to that of the semiconductor substrate. The method of forming the source and drain regions of the transistor of the semiconductor device includes the step of depositing a refractory metal film on the second amorphous silicon film. A step of reacting the refractory metal film with the second amorphous silicon film by a first rapid heat treatment to form a refractory metal silicide film, and etching the unreacted refractory metal film. And a step of implanting an impurity of a conductivity type opposite to that of the semiconductor substrate into the refractory metal film by an ion implantation method, and a second rapid heat treatment to change the refractory metal silicide film into a stable crystal structure. And a step of depositing an interlayer insulating film thereon and then performing a heat treatment to activate impurities having a conductivity type opposite to that of the substrate and diffuse the impurities to the semiconductor substrate.

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

[0007]

EXAMPLES The semiconductor device and the method for manufacturing the same according to the present invention will be described in detail below with reference to examples. FIG. 1 is a plan view (a) of a semiconductor device of the present invention and a cross-sectional view (b) taken along the line AA ′ in FIG. 2 (a) to (c) and FIG.
4D to 4F and FIGS. 4G to 4I are cross-sectional views in order of the steps of the transistor of the present invention.

First, as shown in FIG. 2A, a field oxide film 202 is formed on a semiconductor substrate 201 (P-type semiconductor substrate in this embodiment).

Next, as shown in FIG. 2B, a gate oxide film 203 is formed in the active region surrounded by the field oxide film.
Is formed and the polycrystalline silicon film 204 is embedded. In this embodiment, as a method of embedding a polycrystalline silicon film, a photoresist is applied after the polycrystalline silicon film is deposited and planarization is performed, and the etching conditions are not selective between the polycrystalline silicon film and the photoresist. It is formed by etching back until the field oxide film is exposed. However, as the area shrinks in the future, planarization becomes possible only by depositing a polycrystalline silicon film.

Next, a refractory metal film (a titanium film in this embodiment) is deposited, and the first RTA process is performed, for example, in a nitrogen atmosphere at 625 ° C. for about 20 seconds, and a metastable titanium silicide layer 205 is formed. And the unreacted titanium metal is removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide solution. Impurity ions of opposite conductivity type to the substrate (arsenic ions in this embodiment) are, for example, 40 Kev in this embodiment. After implanting a dose of about 1E16 / cm 2 into the titanium silicide film 205 with an implantation energy of about 2 ° C., a second RTA process is performed, for example, in a nitrogen atmosphere at 900 ° C. for about 20 seconds to perform the titanium silicide film 205. Stable, TiSi2
2C is obtained by changing to the C54 crystal structure.

Next, as shown in FIG. 3D, a conductor film (a titanium silicide film 206 in this embodiment) and an oxide film 207 are sequentially deposited.

Next, as shown in FIG. 3E, the oxide film 207, the conductor film (titanium silicide film 206), the titanium silicide film 205, and the polycrystalline silicon film are formed using the photoresist as a mask for the word line pattern. 204 is sequentially etched to form a word line 209 in which the gate electrode 208 is embedded on the active region. Next, FIG.
As shown in (f), after the oxide film is deposited, the oxide film is etched back until the silicon substrate is exposed on the active region to form a sidewall oxide film 210 on the sidewall of the word line 209 and the gate electrode 208. .

Next, as shown in FIG. 4G, a polycrystalline silicon film 211 is embedded in a region sandwiched by the word line 209 and the gate electrode 208 to prevent a short circuit with an adjacent active region. The polycrystalline silicon film 211 is patterned and separated on the element isolation region (region a in FIG. 1B). Here, in this embodiment, after depositing a polycrystalline silicon film until the surface is flattened, the word line 209 is formed.
Etching back is performed until the oxide film 207 on the upper portion is exposed to fill the polycrystalline silicon film 211.

Next, as shown in FIG. 4H, a refractory metal film (a titanium film in this embodiment) is deposited and a third RT film is deposited.
A treatment is performed, for example, in a nitrogen atmosphere at 625 ° C. for about 20 seconds to form a metastable titanium silicide layer 212,
Unreacted titanium metal is removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide solution, and then impurity ions of the opposite conductivity type to the substrate (arsenic ions in this embodiment) are used for 95% or more of the dose. With the energy for implanting into the titanium silicide film 212, for example, in the present embodiment, with an implant energy of about 35 Kev, after implanting a dose amount of about 5E15 / cm 2 into the titanium silicide film 212, the fourth process is performed. RTA treatment is performed, for example, in a nitrogen atmosphere at 900 ° C.
The titanium silicide film 212 is transformed into a stable TiSi2C54 crystal structure for about 20 seconds.

Next, as shown in FIG. 4I, a source / drain region 214 reaching the semiconductor substrate 201 is formed by depositing an interlayer insulating film 213 and then performing a heat treatment at 900 ° C. for about 15 minutes. As ions in the gate electrode are sufficiently activated.

Finally, a contact hole is formed and an upper wiring is formed to obtain the semiconductor device shown in FIG.

(Embodiment 2) The method for forming a silicide layer according to the present invention is not limited to the first embodiment.

As the silicidation of the polycrystalline silicon film,
Refractory metal ions such as Ti ions are implanted into the polycrystalline silicon films 204 and 211 by an ion implantation method to make the surfaces of the polycrystalline silicon films 204 and 211 amorphous. Next, a refractory metal film made of the same metal as the refractory metal, for example, a Ti film in this embodiment is deposited. Then the first RTA
The treatment 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 and the Ti film with the silicon in the polycrystalline silicon film, so that a metastable titanium silicide layer 205 is formed. , 212 are 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 those in the first embodiment.

In the first and second embodiments, an amorphous silicon film may be used instead of the polycrystalline silicon films 204 and 211. 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.

[0021]

As is apparent from the above, according to the present invention, the gate electrode is embedded in the active region surrounded by the element isolation region via the gate insulating film, and the gate electrode and the element isolation region are provided. There is a word line, and the sidewalls of the gate electrode and the word line and the upper part of the word line are covered with an insulating film, and the region sandwiched by the word line and the gate electrode has an upper part reaching the semiconductor substrate. Since the transistor element is characterized in that the source and drain regions formed by the silicide film are buried, impurities are diffused from the silicide layer formed above the channel part, so that a very shallow junction is formed. And the short channel effect of the transistor can be suppressed. Further, since the silicide region does not reach the semiconductor substrate, the leak current is small. Furthermore, since a silicide layer having a very low resistance is formed, and it is not necessary to provide a contact region on the active region, the diffusion layer area (active region) can be designed to be very small, so that the diffusion layer parasitic resistance can be reduced. In addition to improving the transistor speed, the aspect ratio of the contact hole can be reduced.

In the transistor forming process, a gate oxide film and a gate electrode are formed, a polycrystalline silicon film is deposited, and the stacked diffusion layer regions (source and drain regions) are self-aligned and separated by etchback. ) Is formed, there is no damage to the channel portion as in the conventional example of FIG.

[Brief description of drawings]

FIG. 1 is a plan view (a) of a semiconductor device according to the present invention and a sectional view (b) taken along the line AA ′ in FIG.

2A to 2C are cross-sectional views in order of the processes of a transistor according to the present invention.

3A to 3F are sectional views (d) to (f) in order of steps of the transistor of the present invention.

4A to 4I are cross-sectional views in order of the processes of the transistor of the present invention.

5A to 5D are cross-sectional views in order of steps of a transistor in a conventional example.

[Explanation of symbols]

 101, 201, 301 Semiconductor substrate 102, 202, 302 Field oxide film 303 Polycrystalline silicon film 304 Oxide film 103, 203, 305 Gate oxide film 204 Polycrystalline silicon film 205 Silicide film 206 Silicide film 207 Oxide film 104, 208, 306 Gate electrode 105, 209 Word line 210 Sidewall oxide film 211 Polycrystalline silicon film 106, 212 Silicide film 107, 213 Interlayer insulating film 108, 214, Source / drain region 109 Contact hole 110 Upper wiring 307 Ti silicide film 308 Source / drain region

Claims (6)

[Claims] 1. In a transistor of a semiconductor device, a gate electrode is embedded in an active region surrounded by an element isolation region via a gate insulating film, and a word line is formed on the gate electrode and the element isolation region. The gate electrode, the side wall of the word line and the upper part of the word line are covered with an insulating film, and the region sandwiched by the word line and the gate electrode has source and drain regions reaching the semiconductor substrate. A semiconductor device characterized by being embedded. 2. A step of forming a transistor in a semiconductor device, the step of forming an element isolation region on a semiconductor substrate, the step of forming a gate insulating film, and the gate in an active region surrounded by the element isolation region. A step of burying the first polycrystalline silicon film via an insulating film, a step of selectively forming the first refractory metal silicide film only on the surface of the first polycrystalline silicon film, a conductive film, A step of sequentially depositing a first insulating film, patterning the first polycrystalline silicon film, the first refractory metal silicide film, the conductive film, and the first insulating film into a word line pattern, Forming a gate electrode in the active region surrounded by the element isolation region; forming a second insulating film on the side wall of the gate electrode and the word line; and forming the active region in the region sandwiched by the word line and the gate electrode. Reach the territory In order to prevent a short circuit between the step of burying the second polycrystalline silicon film and the adjacent active region,
The second refractory metal silicide film is formed in a self-aligned manner only on the surface of the second polycrystalline silicon film by patterning the second polycrystalline silicon film and separating it on the element isolation region. A method of manufacturing a semiconductor device, comprising: forming a source / drain region reaching the semiconductor substrate with an impurity having a conductivity type opposite to that of the semiconductor substrate. 3. A method for forming a source / drain region of a transistor of a semiconductor device according to claim 2, wherein a refractory metal film is deposited on the second polycrystalline silicon film. A step of reacting the refractory metal film with the second polycrystalline silicon film by a first rapid heat treatment to form a refractory metal silicide film; and a step of etching away the unreacted refractory metal film. A step of implanting an impurity having a conductivity type opposite to that of the semiconductor substrate into the refractory metal film by an ion implantation method; a step of changing the refractory metal silicide film into a stable crystal structure by a second rapid heat treatment; After the interlayer insulating film is deposited on the semiconductor substrate, a heat treatment is performed to activate impurities having a conductivity type opposite to that of the semiconductor substrate and diffuse the impurities to the semiconductor substrate. Body device manufacturing method. 4. A method of forming a source / drain region of a transistor of a semiconductor device according to claim 2, wherein a refractory metal is implanted into the surface of the second polycrystalline silicon film by an ion implantation method, A step of amorphizing the surface of the second polycrystalline silicon film, a step of depositing a refractory metal film made of the refractory metal on the second polycrystalline silicon film, and a first rapid heating A step of reacting the refractory metal in the polycrystalline silicon film and the refractory metal film with silicon atoms in the second polycrystalline silicon film to form a refractory metal silicide film by a treatment; A step of etching away the refractory metal film of the reaction, a step of implanting impurities of a conductivity type opposite to that of the semiconductor substrate by an ion implantation method, and a second rapid heat treatment for stabilizing the refractory metal silicide film. And a step of depositing an interlayer insulating film thereon and activating heat treatment to activate impurities having a conductivity type opposite to that of the semiconductor substrate and diffusing the impurities to the semiconductor substrate. A method of manufacturing a semiconductor device, comprising: 5. The method of manufacturing a semiconductor device according to claim 2 or 3, wherein the first or second semiconductor device is manufactured.
A method of manufacturing a semiconductor device, characterized in that the first and second amorphous silicon films are used instead of the polycrystalline silicon film. 6. A method of manufacturing a semiconductor device, wherein the refractory metals according to claims 3, 4, and 6 are Ti, Co, Ni, Zr, V, and Hf.