JPH0878362A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE: To provide a manufacturing method, of a semiconductor device, in which the density of an electrode extraction part can be made high in the comparatively small number of processes. CONSTITUTION: A polycrystal silicon film 14 which has a high-melting-point metal film 15 at the upper part via a silicon oxide film 13 is formed on a silicon substrate 11. After that, a polycrystal silicon film 19 is formed on the whole face. The high-melting-point metal film 15 and the polycrystal silicon film 19 at its upper part are reacted by a heat treatment. Thereby, a silicide film 20 is formed. After that, a wet etching operation is performed by a solution which is composed mainly of sulfuric acid, the silicide film 20 is removed, and extraction electrodes 19' are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a method of manufacturing a semiconductor device suitable for increasing the density of electrode lead portions and miniaturizing an element region.

[0002]

2. Description of the Related Art In recent years, high integration of semiconductor IC devices has been remarkable, and pattern dimensions have been reduced to submicron order. Therefore, the mask alignment of photolithography during the manufacturing of semiconductor devices is
It has become an obstacle to miniaturization of semiconductor devices.

In particular, the source / drain regions of the MOS transistor have their areas determined by the mask alignment precision when forming the electrode lead-out portion, and the desired precision cannot be achieved. It was difficult.

Therefore, a method for increasing the density of the electrode lead-out portion by forming the electrode lead-out portion in a self-aligned manner has been proposed. For example, Japanese Patent Publication No. 5-81051 (published on November 11, 1993). )It is described in.

A conventional method of manufacturing a semiconductor device will be described below with reference to FIG.

FIG. 3 is a schematic sectional view showing a conventional method of manufacturing a MOS transistor in the order of steps.

First, as shown in FIG. 3A, the field oxide film 2 is formed on the silicon substrate 21 by the LOCOS method.
After forming 2, the silicon oxide film 23 is formed by thermal oxidation. Then, after depositing the polycrystalline silicon film 24 on the entire surface by the chemical vapor deposition method, the polycrystalline silicon film 24 is deposited.
Impurities are ion-implanted into the. Next, this polycrystalline silicon film 24 is patterned into the shape of the gate electrode by the photolithography method, and the polycrystalline silicon film 2 is formed.
Ion implantation is performed using 4 as a mask to form a low-concentration impurity diffusion layer 26. Then, after depositing a silicon oxide film on the entire surface by chemical vapor deposition, R
By etching back using the IE method, the sidewall insulating film 25 is formed on the sidewall of the gate electrode 24.

Next, as shown in FIG. 3B, a polycrystalline silicon film 27 is deposited on the entire surface by a chemical vapor deposition method.

Next, as shown in FIG. 3 (c), after heat treatment is performed in an oxygen atmosphere, impurities contained in the polycrystalline silicon film 24 are removed from the polycrystalline silicon film 27 over the nitrogen atmosphere in a nitrogen atmosphere. A polycrystalline silicon film 28 containing a large amount of impurities is formed by diffusing into the inside.

Next, as shown in FIG. 3D, after heat treatment is performed in a steam atmosphere, the polycrystalline silicon films 27 and 2 are formed.
The silicon oxide film (not shown) formed on 8 is removed with a hydrofluoric acid-based aqueous solution, and then a molybdenum film 29 is formed on the entire surface.

Next, as shown in FIG. 3E, a molybdenum film 29 is reacted with the polycrystalline silicon film 28 in which impurities are diffused by heat treatment to form a molybdenum silicide film 30.

Next, as shown in FIG. 3F, after removing the molybdenum film 29, impurities are implanted by ion implantation to form a high-concentration impurity diffusion layer 31.

Finally, as shown in FIG. 3 (g), KOH
The molybdenum silicide film 30 is selectively removed with an aqueous solution / isopropyl alcohol to form a lead electrode 27 'of the diffusion layer 26.

[0014]

In the conventional manufacturing method described above, the step of forming the polycrystalline silicon film 27 or the molybdenum film 29 to form the extraction electrode 27 'of the diffusion layer 26, or the steps of forming the polycrystalline silicon film 24 And the like, a step of diffusing the impurities in the polycrystalline silicon film 27 to form the impurity-doped polycrystalline silicon film 28, a step of performing heat treatment for reacting the molybdenum film 29 and the polycrystalline silicon film 28, and the like However, there is a problem in that the number of steps is required, which causes a decrease in throughput and a deterioration in manufacturing yield.

Therefore, an object of the present invention is to provide a method of manufacturing a semiconductor device capable of miniaturizing an electrode lead-out portion of a source / drain such as an insulated gate field effect transistor (FET) with a relatively small number of steps. It is to be.

Another object of the present invention is to provide a method of manufacturing an insulated gate FET in a semiconductor IC device.

Another object of the present invention is to provide an insulated gate FET in a semiconductor IC device which can be manufactured by a relatively small number of steps.

[0018]

In order to solve the above-mentioned problems, a method of manufacturing a semiconductor device according to the present invention comprises a step of forming a conductive film having a refractory metal at least on a semiconductor substrate, Patterning the film to form an electrode, forming a sidewall insulating film on the side wall of the electrode, forming a polycrystalline silicon film over the entire surface, and forming the polycrystalline silicon film on the refractory metal And a step of selectively silicidizing the silicon by heat treatment, and a step of selectively removing the silicidized portion.

According to one aspect of the present invention, there is a step of introducing impurities into the polycrystalline silicon film.

In one aspect of the present invention, the refractory metal is at least one metal selected from the group consisting of titanium, tantalum, molybdenum and tungsten.

In another aspect of the method for manufacturing a semiconductor device of the present invention, a step of forming an insulating film on a semiconductor substrate, a step of forming a refractory metal film on the insulating film, and the refractory metal film And a step of patterning the insulating film to form a gate electrode made of the refractory metal film; and doping the semiconductor substrate with impurities by using the gate electrode as a mask to form the gate electrode on the surface portion of the semiconductor substrate. Forming an impurity diffusion layer on both sides of the upper surface of the semiconductor substrate, forming a polycrystalline silicon film on the surface of the semiconductor substrate and on the upper surface of the refractory metal film, and performing heat treatment on the upper surface of the refractory metal film. There is a step of forming the above polycrystalline silicon film as a silicide film and a step of removing the silicide film.

In one aspect of the present invention, the method further comprises the step of forming a conductive film between the insulating film and the refractory metal film, the conductive film being the refractory metal film and the insulating film. The gate electrode includes the refractory metal film and the conductive film by patterning together.

In one aspect of the present invention, a step of forming the impurity diffusion layer, and then forming a sidewall insulating film that covers a side surface of the gate electrode,
And a step of doping the semiconductor substrate with impurities using the gate electrode and the sidewall insulating film as a mask, wherein the polycrystalline silicon film is on the surface of the semiconductor substrate and on the upper surface of the refractory metal film. At the same time, it is formed on the sidewall insulating film.

In one aspect of the present invention, the step of removing the silicide film is performed by wet etching.

Further, the semiconductor device of the present invention is a gate which is formed on a semiconductor substrate via an insulating film and has a refractory metal film and a silicide film formed between the refractory metal film and the insulating film. The semiconductor device includes an electrode, a pair of impurity diffusion layers formed on both sides of the gate electrode on a surface portion of the semiconductor substrate, and an extraction electrode formed on each of the pair of impurity diffusion layers.

In another aspect of the semiconductor device of the present invention, an insulating film is interposed between the source / drain doped region formed on the surface portion of the semiconductor substrate and the source / drain doped region on the semiconductor substrate. And a gate electrode made of a refractory metal film formed as described above, and source / drain lead-out electrodes respectively formed on the source / drain doped regions.

[0027]

[Function] A polycrystalline silicon film is formed on a patterned conductive film whose upper portion is made of a refractory metal, and only the polycrystalline silicon film on the refractory metal is silicided by heat treatment. Therefore, only this silicide film can be easily formed. You will be able to remove it. As a result, since the polycrystalline silicon film can be patterned in a self-aligned manner with the electrodes sandwiched, the lead-out electrodes can be densified with a small number of steps.

According to one aspect of the present invention, in manufacturing an insulated gate FET in a semiconductor device, a refractory metal film is formed on an upper portion of a semiconductor substrate with an insulating film interposed. An insulating gate electrode is formed by patterning the refractory metal film and the insulating film. After the source / drain regions were formed in the surface portion of the substrate in a self-aligned manner using the patterned refractory metal film of the gate electrode and the patterned insulating film as a mask, the surface portion of the substrate and the gate electrode were patterned. A refractory metal film and a doped polycrystalline silicon film extending to cover the patterned refractory metal film and the side surface of the lower insulating film are formed. The obtained structure is heated, whereby the portion of the doped polycrystalline silicon film on the patterned refractory metal film is converted into the silicide film portion, and the source / drain region in the surface portion of the semiconductor substrate is converted. The converted silicide film portion is removed while leaving the portion of the doped polycrystalline silicon film above. The portions of the doped polycrystalline silicon film act as source / drain electrodes.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor IC device according to an embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a semiconductor I according to an embodiment of the present invention.
FIG. 6 is a schematic cross-sectional view showing the method of manufacturing the insulated gate FET in the C device in the order of steps. In this embodiment, the insulated gate FE
T is a MOS transistor.

First, as shown in FIG. 1A, the LOCO
The field oxide film 12 is formed in the element isolation region of the P-type silicon substrate 11 by the S method or the like.

Next, as shown in FIG. 1B, the temperature is 1
The silicon oxide film 13 is formed to a film thickness of 150 to 200Å by a thermal oxidation method at 000 to 1100 ° C. And
A polycrystalline silicon film 14 is deposited to a film thickness of 1500 to 2000 Å by a CVD method using a temperature of 600 to 650 ° C., and impurities such as phosphorus are ion-implanted into the polycrystalline silicon film 14. After that, a refractory metal film 15 is formed on the polycrystalline silicon film 14 by, for example, a sputtering method, for example, 1500-2.
Then, the polycrystalline silicon film 14 and the refractory metal film 15 are patterned into a gate electrode shape by photolithography. Here, as the refractory metal film 15, a metal such as titanium, tantalum, molybdenum, or tungsten can be used. Further, titanium, tantalum, molybdenum, tungsten and the like can be etched with sulfuric acid. Here, the refractory metal means a transition metal having a melting point of 100 ° C. or higher and capable of withstanding heat treatment at high temperature after deposition.

Next, by using the polycrystalline silicon film 14 and the refractory metal film 15 as a mask, ions of phosphorus, arsenic, or the like are implanted to form a low-concentration N-type impurity diffusion layer 17 in a self-aligning manner. After depositing a silicon oxide film (not shown) on the entire surface by the vapor phase growth method, that is, on the surfaces of the substrate 11 and the refractory metal film 15 and on the side surfaces of the polycrystalline silicon film 14 and the refractory metal film 15, RIE is performed. Etching back is performed to form the sidewall insulating film 16 on the sidewalls of the polycrystalline silicon film 14 and the refractory metal film 15. In this example, the sidewall insulating film 1
Although 6 is formed of a silicon oxide film, it may be formed of a silicon nitride film.

Next, as shown in FIG. 1C, ion implantation of phosphorus, arsenic or the like is performed using the polycrystalline silicon film 14, the refractory metal film 15 and the sidewall insulating film 16 formed on the side walls thereof as a mask. By doing so, the high-concentration N-type impurity diffusion layer 18 is formed in a self-aligned manner.

Next, as shown in FIG. 1D, a polycrystalline silicon film 19 doped by a method such as CVD is formed.
It is formed on the entire surface so as to have a film thickness of 500 to 2000Å.

Next, as shown in FIG. 1 (e), heat treatment is performed in a nitrogen atmosphere at 900 ° C. for about 15 to 20 minutes to form the refractory metal film 15 and the polycrystalline silicon film 19 above it. Are reacted to form the silicide film 20. By this heat treatment, the polycrystalline silicon film 14 is also silicidized and becomes a doped silicide film. The polycrystalline silicon film 19 has impurity diffusion layers 18, 19
Impurities are doped by outward diffusion from the.

Next, as shown in FIG. 1F, the silicide film 20 is selectively removed by wet etching,
The extraction electrode 19 'is formed.

At this time, the lead electrode 19 and the refractory metal film 15 may come into contact with each other due to the selective removal of the silicide film 20, but as described above, the formation of the silicide film 20 by the heat treatment takes 15 to 20 minutes. To do about
As shown in FIG. 1E, the end of the silicide film 20 reaches above the sidewall insulating film 16 formed on the side surface of the refractory metal film 15. Therefore, the silicide film 20
Since the end portion of the lead electrode 19 'is located above the side wall insulating film 16 even if is removed, the side wall insulating film 16 is necessarily located between the lead electrode 19' and the refractory metal 15. And the extraction electrode 1
9'and the refractory metal film 15 do not come into contact with each other.

When the silicide film 20 is etched, only the silicide film 20 can be selectively removed by using a solution containing sulfuric acid as a main component, and the polycrystalline silicon film and the gate forming the extraction electrode 19 'can be removed. The refractory metal film 15 forming the electrode is not removed. Further, it is possible to prevent the sidewall insulating film 16 from being etched by controlling conditions such as temperature and time during etching. Alternatively, etching with a hydrogen fluoride solution or the like may be performed.

Finally, as shown in FIG. 2, after the interlayer insulating film 43 is formed by coating on the entire surface of the substrate, the lead electrode 19 'of the interlayer insulating film 43 is electrically connected to the MOS transistor and the outside. Contact hole 41 at the corresponding location
To form. Then, a metal film of aluminum or the like is formed on the surface of the interlayer insulating film 43 and in the contact hole 41, and the metal film is patterned to form the metal wiring 42 that connects the extraction electrode 19 'to the outside.

In the above embodiment, N channels M
The case of forming the extraction electrode of the OS transistor has been described, but the invention may be applied to a P-channel MOS transistor or may be applied to the case of forming a pad polycrystalline silicon film in the field shield element isolation method.

Further, the example of the two-layer structure of the polycrystalline silicon film 14 and the refractory metal film 15 has been described as the gate electrode, but the polycrystalline silicon film 14 may be omitted.

As described above, according to the manufacturing method of this embodiment, the extraction electrode can be formed on the source / drain regions of the MOS transistor in a self-aligned manner.
The area of the drain region can be miniaturized to achieve high integration of the device, and the parasitic capacitance and the parasitic resistance can be significantly reduced to achieve high speed operation of the device.

Further, the patterning of the polycrystalline silicon film 19 for forming the extraction electrode 19 'is carried out by utilizing the reaction with the refractory metal film 15 formed on the upper part of the gate electrode. Can also simplify the process.

[0045]

According to the present invention, since a polycrystalline silicon film is formed on a patterned refractory metal film and silicidized, the polycrystalline silicon film can be patterned in a self-aligned manner, so that the number of steps is reduced. Depending on the number, the density of the electrode lead-out portion can be increased.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a method of manufacturing a MOS transistor according to an embodiment of the present invention in the order of steps.

FIG. 2 is a schematic cross-sectional view showing a method of manufacturing a MOS transistor according to an embodiment of the present invention in the order of steps.

FIG. 3 is a schematic cross-sectional view showing a method of manufacturing a conventional MOS transistor in the order of steps.

[Explanation of symbols]

 11 P-type silicon substrate 12 Field oxide film 13 Silicon oxide film 14, 19 Polycrystalline silicon film 15 Refractory metal film 16 Sidewall insulating film 17 Low-concentration N-type impurity diffusion layer 18 High-concentration N-type impurity diffusion layer 19 ' Lead electrode 20 Silicide film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 21/768 H01L 21/90 C

Claims (18)

[Claims] 1. A step of forming a conductive film having at least an upper portion made of a refractory metal on a semiconductor substrate, a step of patterning the conductive film to form an electrode, and forming a sidewall insulating film on a sidewall of the electrode. A step of forming a polycrystalline silicon film on the entire surface, a step of siliciding the polycrystalline silicon film on the refractory metal by heat treatment, and a step of selectively removing the silicidized portion. A method of manufacturing a semiconductor device, comprising: 2. The method of manufacturing a semiconductor device according to claim 1, further comprising the step of introducing impurities into the polycrystalline silicon film. 3. The manufacturing of a semiconductor device according to claim 1, wherein the refractory metal is at least one kind of metal selected from the group consisting of titanium, tantalum, molybdenum and tungsten. Method. 4. A step of forming an insulating film on a semiconductor substrate, a step of forming a refractory metal film on the insulating film, a step of patterning the refractory metal film and the insulating film, and the refractory metal film. And a step of forming an impurity diffusion layer on both sides of the gate electrode on a surface portion of the semiconductor substrate by doping impurities into the semiconductor substrate using the gate electrode as a mask, Forming a polycrystalline silicon film on the surface of the semiconductor substrate and on the upper surface of the refractory metal film; and performing a heat treatment to form the polycrystalline silicon film on the upper surface of the refractory metal film into a silicide film. And a step of removing the silicide film, the method for manufacturing a semiconductor device. 5. The method further comprises the step of forming a conductive film between the insulating film and the refractory metal film, and by patterning the conductive film together with the refractory metal film and the insulating film, The method of manufacturing a semiconductor device according to claim 4, wherein the gate electrode includes the refractory metal film and the conductive film. 6. A step of forming a side wall insulating film covering a side surface of the gate electrode after performing a step of forming the impurity diffusion layer, and the semiconductor using the gate electrode and the side wall insulating film as a mask. And a step of doping the substrate with impurities, wherein the polycrystalline silicon film is formed not only on the surface of the semiconductor substrate and on the upper surface of the refractory metal film but also on the sidewall insulating film. The method of manufacturing a semiconductor device according to claim 4, wherein the method is a semiconductor device manufacturing method. 7. The method of manufacturing a semiconductor device according to claim 4, wherein the step of removing the silicide film is performed by wet etching. 8. A gate electrode formed on a semiconductor substrate via an insulating film, the gate electrode having a refractory metal film and a silicide film formed between the refractory metal film and the insulating film; A semiconductor device comprising: a pair of impurity diffusion layers formed on both sides of the gate electrode on a surface portion; and lead electrodes formed on the pair of impurity diffusion layers, respectively. 9. The semiconductor device according to claim 8, wherein sidewall insulating films are formed on both sides of the gate electrode. 10. The semiconductor device according to claim 8, wherein the refractory metal film is made of at least one metal selected from the group consisting of titanium, tantalum, molybdenum, and tungsten. 11. The semiconductor device according to claim 9, wherein the sidewall insulating film is a silicon oxide film or a silicon nitride film. 12. The pair of impurity diffusion layers each have a double-doped region formed by the sidewall insulating film in a self-aligned manner.
The semiconductor device according to. 13. A gate electrode comprising a source / drain doped region formed on a surface portion of a semiconductor substrate, and a refractory metal film formed between the source / drain doped region on the semiconductor substrate with an insulating film interposed therebetween. And a source / drain lead electrode formed on the source / drain doped region, respectively. 14. The method according to claim 13, further comprising lead electrodes formed on the source / drain doped regions, and sidewall insulating films formed on both sides of the gate electrode. Semiconductor device. 15. The semiconductor device according to claim 13, wherein the refractory metal film is made of at least one metal selected from the group consisting of titanium, tantalum, molybdenum, and tungsten. 16. The semiconductor device according to claim 14, wherein the sidewall insulating film is a silicon oxide film or a silicon nitride film. 17. The semiconductor device according to claim 14, wherein each of the source / drain doped regions has a double doped region formed by the sidewall insulating film in a self-aligned manner. 18. The semiconductor device according to claim 13, wherein the gate electrode further comprises a silicide film formed between the refractory metal film and the insulating film.