JPH05234934A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable the fine process of a polycide film and prevent the generation of contamination on the interface between poly silicon and silicide, by forming a high melting point metal film in an aperture formed in a low pressure vapor growth film, and forming silicide by performing a heating process. CONSTITUTION:Polycrystalline silicon 13 in which impurities are introduced is formed, a mask film 15 is formed thereon, and an aperture is formed. A vapor growth film 17 is formed on the whole surface by a CVD method in a low pressure atmosphere, and a flattened film 21 is formed on the film 17. Etching is performed under the condition where the flattened film 21 and the vapor growth film 17 have nearly equal etching rates, and an aperture 28 having the aperture width corresponding to the thickness of the mask film 15 is formed. A high melting point metal film 29 is formed on the whole surface, and silicide is formed by a heating process. The high melting point metal film 29 and the mask film 15 are eliminated, and silicide 31 is formed on the ploycrystalline silicon 13. By using the silicide 31 as a mask, the polycrystalline silicon 13 is etched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to manufacturing a wiring and a gate electrode using a polycide film having a laminated film structure of polycrystalline silicon and a silicide which is a silicon compound of a refractory metal. Regarding the method.

[0002]

2. Description of the Related Art A conventional method for manufacturing a polycide film having a laminated structure of polycrystalline silicon and silicide will be described with reference to FIG. 8A to 8C are cross-sectional views showing a conventional method for forming a polycide film in the order of steps.

First, as shown in FIG. 8A, polycrystalline silicon (hereinafter referred to as polysilicon) 13 is formed on a semiconductor substrate 11 by a chemical vapor deposition method (hereinafter referred to as CVD method). Impurities such as phosphorus, arsenic, and boron are introduced into the polysilicon 13 by a method such as a doping method or an ion implantation method in order to make the polysilicon 13 conductive. After that, the impurities introduced by the high temperature heat treatment are activated, and the conductive polysilicon 1
3 is formed.

After that, a silicon compound of a refractory metal (hereinafter referred to as silicide) 3 is formed on the polysilicon 13.
As 3, a tungsten silicide film is formed by using a sputtering method.

Thereafter, as shown in FIG. 8 (b), a photosensitive resin 35 is formed on the entire surface of the silicide 33 by a spin coating method, exposed by using a predetermined mask, and subjected to a developing treatment to form a photosensitive resin. 35 is patterned.

Next, as shown in FIG. 8C, the silicide 33 and the polysilicon 13 are etched by using a reactive ion etching device with the patterned photosensitive resin 35 as an etching mask, and the polysilicon 1
A polycide film made of a laminated film of 3 and silicide 33 is formed.

[0007]

In the conventional manufacturing method described with reference to FIGS. 8A to 8C, the processed line width of the polycide film is the line width of the photosensitive resin used as an etching mask. Depends on.

That is, since the microfabrication by the conventional method depends on the line width of the mask, it depends on the wavelength of the light that sensitizes the photosensitive resin, and the microfabrication technique will eventually reach its limit. ..

Furthermore, since the silicide is formed on the polysilicon by the sputtering method, the interface between the silicide and the polysilicon is contaminated.

An object of the present invention is to solve the above problems and provide a manufacturing method capable of finely processing a polycide film, and further a method for forming a polycide film in which contamination does not occur at the interface between polysilicon and silicide. To do.

[0011]

In order to achieve the above object, the polycide film forming method of the present invention employs the following steps.

According to the method of manufacturing a semiconductor device of the present invention, a step of forming polysilicon into which impurities are introduced, forming a mask film on the polysilicon, and forming an opening in the mask film by photoetching, and depressurizing the entire surface. A step of forming a vapor phase growth film by a chemical vapor deposition method in an atmosphere, a step of forming a planarization film on the vapor phase growth film, and the same etching rate for the planarization film and the vapor phase growth film. Under the following conditions to form an opening having an opening width corresponding to the film thickness of the mask film, a refractory metal film is formed on the entire surface, and heat treatment is performed to react the refractory metal film with the polysilicon film. And forming a silicide, removing the refractory metal film and the mask film, forming a silicide on the polysilicon, and etching the polysilicon using the silicide as a mask. Characterized in that it has and.

[0013]

In the present invention, since the polycide film is not processed by using an etching mask made of a photosensitive resin, there is no limit to the fine processing, and contamination at the interface between silicide and polysilicon, which is a problem during the fine processing, is prevented. Can be prevented.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 are sectional views showing a method of manufacturing a polycide film according to the present invention in the order of steps.

First, as shown in FIG. 1, polysilicon 13 is formed on the entire surface of a semiconductor substrate 11 by a CVD method using monosilane as a reaction gas.

Thereafter, impurities such as phosphorus, arsenic, and boron are introduced by a doping method, an ion implantation method, or the like in order to make the polysilicon 13 conductive. Further, heat treatment is performed at a temperature of 900 to 1000 ° C. to activate the introduced impurities. The polysilicon 13 in which the impurities are activated becomes a film having electrical conductivity and can be used as a wiring or a gate electrode.

Further, for example, a silicon oxide film is formed as a mask film 15 on the polysilicon 13 by a CVD method using monosilane and oxygen as reaction gases.

After that, a photosensitive resin (not shown) is formed on the entire surface by a spin coating method, exposed using a predetermined mask, and developed to pattern the photosensitive resin. Further, the mask film 15 is etched by using the patterned photosensitive resin as an etching mask to pattern the mask film 15. Then, the photosensitive resin used as the etching mask is removed.

Next, as shown in FIG. 2, a silicon nitride film, for example, is formed as the vapor phase growth film 17 on the entire surface by a CVD method under a reduced pressure atmosphere, for example, a plasma CVD method. As a result, the recess 19 corresponding to the opening of the mask film 15 is formed.

In the manufacturing method of the present invention, since the film thickness of the vapor phase growth film 17 matches the processing line width dimension of the polycide film, by controlling the film thickness of the vapor phase growth film 17, the polycide film of the polycide film can be formed. Controls the pattern width dimension.

Next, as shown in FIG. 3, as the flattening film 21, for example, a spin-on-glass (hereinafter referred to as SOG) film is formed on the entire surface by a spin coating method, and the recess 19 is formed.
Are embedded to form a flattening film 21 having a substantially flat surface.

After the SOG film, which is the flattening film 21, is applied,
In order to perform vitrification, heat treatment is performed at a temperature of 350 to 400 ° C. in a nitrogen atmosphere under normal pressure or reduced pressure.

As the flattening film 21, a polymer resin film such as a resist or polyimide can be applied other than the SOG film.

Next, the entire surface is etched under the condition that the flattening film 21 and the vapor growth film 17 shown in FIG. 3 have substantially the same etching rate.

A reactive etching device is used as the etching device. As this reactive etching apparatus, for example, an anode-coupled reactive etching apparatus in which the sample electrode side of the parallel plate electrode is a high frequency is used.

The high frequency is 13.56 MHz, the high frequency power is 150 W, and the pressure in the etching apparatus is 0.5 Tor.
r, sulfur hexafluoride (SF ₆ ) as etching gas
And helium (He) and trifluoromethane (CHF ₃ )
A mixed gas with is used.

The flow rate of each gas is 20 sccm (Standard Cubic Cent) of sulfur hexafluoride.
images per Minute), helium at 50 sccm, and trifluoromethane at 40 sccm
And The etching temperature is 25 ° C.

Under this condition, the etching rates of the flattening film 21 and the vapor growth film 17 are both 180 nm /
Thus, the etching selection ratio, that is, the ratio of the etching rate of the flattening film 21 to the etching rate of the vapor phase growth film 17 becomes 1. Therefore, the flattening film 21 and the vapor growth film 17 are etched at the same etching rate.

At the initial stage of etching under the above etching conditions, the flattening film 21 is removed.

When the etching progresses and a part of the surface of the vapor phase growth film 17 is exposed, the vapor phase growth film 17 starts to be etched next.

At this time, the etching rate of the vapor growth film 17 on the side wall portion 25 of the mask film 15 is 4 to 5 times faster than that of the vapor growth film 17 on the flat portion 23.

The vapor phase growth film 17 has a side wall portion 25 and a flat surface portion 23.
As shown in FIG. 4, the side walls 25 are formed before the flattening film 21 of the concave portion 19 and the vapor phase growth film 17 of the flat portion 23 on the mask film 15 are removed. The vapor phase growth film 17 is completely removed. As a result,
The opening 28 is formed.

This phenomenon that the planar portion 23 and the side wall portion 25 have different etching rates occurs when the vapor phase growth film 17 is formed by the CVD method under a reduced pressure atmosphere, and not only in the silicon nitride film but also in the silicon oxide film. The same phenomenon occurs when the film is formed by the CVD method under a reduced pressure atmosphere.

It is considered that this is because the active species involved in the film formation reach the film formation substrate from a certain direction, which causes a difference in the film deposition mechanism between the vertical direction and the horizontal direction. As a result, the etching rate is significantly different between the side wall portion and the flat portion.

Here, the same shape can be obtained under the etching condition that the etching rate of the silicon nitride film which is the vapor phase growth film 17 is faster than that of the silicon oxide film which is the mask film 15, but the side wall of the vapor phase growth film 17 is obtained. In the region 27, the etching of the silicon nitride film of the vapor phase growth film 17 progresses, and an undercut occurs in the vapor phase growth film 17.

Next, as shown in FIG. 5, the refractory metal film 2
9 is formed on the entire surface. As the refractory metal film 29, for example, a tungsten (W) film is formed by a sputtering method.

After forming the refractory metal film 29 of tungsten, a heat treatment is performed at a temperature of 450 to 650 ° C., whereby tungsten and polysilicon are formed at the interface between the refractory metal film 29 of tungsten and the polysilicon 13. Forming a silicide 31 which is a compound of

Next, as shown in FIG. 6, the unreacted refractory metal film 29 is removed with nitric acid. Furthermore, the vapor phase growth film 1
7 is removed with a mixed solution of hydrofluoric acid and nitric acid.

Further, the mask film 15 is removed with hydrofluoric acid.

As a result, the polysilicon 1 in the opening 28 is
A silicide 31 can be formed on top of 3.

Next, as shown in FIG. 7, the silicide 31
Is used as a mask, and the polysilicon 13 is etched by the reactive ion etching method.

As a result, a polycide film, which is a laminated film of the polysilicon 13 and the silicide 31, can be formed.

[0043]

As is apparent from the above description, in the method for producing a polycide film according to the present invention, the processing line width of the silicide film can be controlled by the film thickness of the vapor phase growth film. Therefore, a polycide film having a fine line width can be formed. Furthermore, the discontinuous interface at the interface between the silicide and the polysilicon is eliminated, contamination at the interface can be prevented, and a polycide film having good film quality can be formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method of manufacturing a semiconductor device according to an embodiment of the invention.

FIG. 2 is a cross-sectional view showing the method of manufacturing a semiconductor device according to the embodiment of the invention.

FIG. 3 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the invention.

FIG. 4 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the invention.

FIG. 5 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the invention.

FIG. 6 is a cross-sectional view showing the method of manufacturing a semiconductor device according to the embodiment of the invention.

FIG. 7 is a cross-sectional view showing the method for manufacturing the semiconductor device in the example of the present invention.

FIG. 8 is a cross-sectional view showing a method of manufacturing a semiconductor device in a conventional example.

[Explanation of symbols]

 11 semiconductor substrate 13 polysilicon 15 mask film 17 vapor phase growth film 21 flattening film 23 plane part 25 sidewall part 28 opening part 31 silicide

Claims (1)

[Claims] 1. In a method of manufacturing a semiconductor device for forming a polycide film having a laminated film structure of polycrystalline silicon and a silicide that is a silicon compound of a refractory metal, polycrystalline silicon into which impurities are introduced is formed, and polycrystalline silicon is formed. A step of forming a mask film on silicon and forming an opening in the mask film by photoetching, a step of forming a vapor phase growth film on the entire surface by a chemical vapor deposition method under a reduced pressure atmosphere, and a step of forming a mask film on the vapor phase growth film. A step of forming a flattening film, a step of forming an opening having an opening width corresponding to the film thickness of the mask film by performing etching under the conditions that the flattening film and the vapor phase growth film have substantially the same etching rate, A step of forming a refractory metal film on the entire surface and performing heat treatment to react the refractory metal film with polycrystalline silicon to form silicide, and removing the refractory metal film and the mask film, A method of manufacturing a semiconductor device, comprising: a step of forming silicide on crystalline silicon; and a step of etching polycrystalline silicon using the silicide as a mask.