JPH1140668A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of the void of a tungsten plug buried by a blanket/tungsten process, and to suppress the deterioration of the step coverages of a wiring film formed on a tungsten plug. SOLUTION: A barrier metal film 4A is formed on an insulating film 2, including a contact hole 3 formed on an insulating film 2 on a semiconductor substrate 1, and then argon(Ar) ions are sputtered on the barrier metal film 4A including the contact hole by a sputtering method. Thus, the overhung part of the barrier metal film 4A formed on the corner part of the contact hole is cut so that a barrier metal film 4 can be shaped, and a tungsten plug can be embedded in the contact hole via the barrier metal film 4.

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 a method of forming a wiring film on a contact plug formed by embedding a tungsten film in a contact hole by a blanket-tungsten process. In this case, the present invention relates to a technique for improving the step coverage of the wiring film.

[0002]

2. Description of the Related Art In recent years, with the increasing integration and miniaturization of semiconductor devices, wiring design rules have been increased from 0.5 μm to 0.3 μm.
The design rule is about to be reduced to the μm rule and even lower. Therefore, the aspect (the ratio of the depth to the width of the groove) of the contact hole formed in the insulating film for connecting the upper layer wiring and the lower layer wiring is increasing with the reduction in design rules.

[0003] A technique related to burying of a contact hole performed at the time of multilayer wiring is disclosed in Japanese Patent Application Laid-Open No. 08-227.
A wiring forming process combining a blanket tungsten CVD method and an etch-back process method as disclosed in Japanese Patent No. 939 and the like is well known. Hereinafter, a conventional technique of a wiring forming process for forming a tungsten plug by a blanket tungsten CVD method and an etch-back process method will be described.

[0004] First, as shown in FIG. 9, for example, TEOS (tetraethoxysilane) formed on a semiconductor substrate 31.
A contact hole 33 is selectively formed in a certain region of the insulating film 32 made of a film or a BPSG film. Next, as shown in FIG. 10, a barrier metal film 34 made of, for example, a titanium film and a titanium nitride film (TiN film) is formed on the insulating film 32 including the inside of the contact hole 33. The barrier metal film 34 functions as an adhesion film for improving the adhesion between a contact plug material made of a tungsten film described later and the insulating film 32.

Subsequently, as shown in FIG. 11, a contact plug material is formed on the entire surface with the barrier metal film 34 interposed therebetween.
For example, a tungsten film 35A is formed. Next, the tungsten film 35A is entirely etched back, and a tungsten plug 35 is buried in the contact hole 33 via a barrier metal film 34 as an adhesion film as shown in FIG.

Subsequently, after a metal film made of, for example, an aluminum film is formed on the entire surface, a photoresist film (not shown) is formed on the metal film, and the metal film is patterned using the resist film as a mask. Then, a wiring film 36 as shown in FIG. 13 was formed.

[0007]

However, in the above-described blanket-tungsten film process, the barrier metal film 34 as an adhesion film formed on the contact hole 33 is formed over the corner of the contact hole 33 as shown in FIG. The barrier metal film 3 is formed in a hung state (see a portion surrounded by a dotted line in FIG. 10).
When the tungsten film 35A is formed on the substrate 4, a void A is formed as shown in FIG. When the upper portion of the void A is opened as shown in FIG. 12 when the tungsten film 35A is etched back, FIG.
As shown in FIG. 3, when the wiring film 36 was formed, a depression B was formed in the wiring film 36 above the void A, resulting in deterioration of the step coverage.

Accordingly, the present invention provides a method of manufacturing a semiconductor device which suppresses generation of voids in a tungsten plug buried by a blanket-tungsten process and suppresses deterioration of step coverage of a wiring film formed on the tungsten plug. The purpose is to do.

[0009]

Accordingly, a method of manufacturing a semiconductor device according to the present invention is directed to a method of manufacturing an insulating film including a contact hole formed selectively in an insulating film on a semiconductor substrate as shown in FIG. After the barrier metal film 4A is formed thereon, the barrier metal film 4A including the inside of the contact hole 3 is sputtered with argon (Ar) ions by a sputtering method as shown in FIG. The overhanging portion of the barrier metal film 4A formed in the above is scraped off, and the barrier metal film 4 is shaped. Next, as shown in FIG. 5, after a tungsten film 5A is formed on the entire surface including the inside of the contact hole 3 via the barrier metal film 4, the tungsten film 5A is etched back, and as shown in FIG. A tungsten plug 5 is buried in the contact hole 3. Then, a wiring film 6 is formed on the tungsten plug 5 as shown in FIG.

Further, the method of manufacturing a semiconductor device according to the present invention comprises:
A tungsten plug 21 is formed in a contact hole 19 formed in a region having a high step portion such as a nonvolatile semiconductor memory device in which a floating gate 15 and a control gate 17 are stacked as shown in FIG. In the case where the wiring film 22 is formed on the tungsten plug 21, after forming the barrier metal film 20 on the interlayer insulating film 18 including the inside of the contact hole 19, the barrier metal film 20 including the inside of the contact hole 19 is formed. By sputtering argon (Ar) ions by the sputtering method,
In particular, the overhanging portion of the barrier metal film 20 formed at the corner of the contact hole is scraped to shape the barrier metal film 20. Next, the barrier metal film 20
After a tungsten film is formed on the entire surface including the inside of the contact hole 19 through the contact hole, the tungsten film is etched back to form a tungsten plug 2 in the contact hole 19.
1 is buried. Then, a wiring film 22 is formed on the tungsten plug 21.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for manufacturing a semiconductor device according to the present invention will be described below with reference to FIGS. First, as shown in FIG. 1, for example, a TEOS (tetraethoxysilane) film or a BP
A contact hole 3 is formed in an insulating film 2 made of an SG film and having a thickness of about 6000-15,000.

Next, as shown in FIG. 2, the entire surface including the inside of the contact hole 3 is made of, for example, a titanium film and a titanium nitride film (TiN film) of about 300.degree.
A barrier metal film 4A having a thickness of 0 ° is formed. The barrier metal film 4A functions as an adhesion film for improving the adhesion between the contact plug material composed of a blanket-tungsten film described later and the insulating film 2. Note that the barrier metal film 4A at this time is formed in an overhang state at the corner of the contact hole 3 as in the conventional case (see a portion surrounded by a dotted line in FIG. 2).

Subsequently, as shown in FIG. 3, the degree of vacuum is 0.1 mTorr, the flow rate of argon (Ar) gas is 50 sccm to 100 sccm, and the frequency is 13.56 M by sputtering.
By hitting the barrier metal 4A with Ar ions at 800 Hz and an output of 800 W, in particular, the barrier metal film 4A in the above-mentioned overhanging portion is cut off and shaped, and as shown in FIG. Multiply.

This step is a step which is a feature of the present invention. Ar sputtering (also referred to as Ar stream etching) is a process in which plasma is produced with Ar gas and the sample surface is beaten with Ar ions to strike. The shaved sample surface is chamfered at about 45 degrees, and the shaved portion is deposited again. Therefore, in the present embodiment, the surface of the barrier metal film 4A is beaten with Ar ions to be shaved, and in particular, the barrier metal film 4A formed in an overhang shape at the corner of the contact hole 3 is scraped off, and the corner is removed. The thickness of the barrier metal film 4 in the portion is reduced, and the upper portion of the contact hole 3 is formed to be tapered.
The shaved barrier metal film 4A is deposited again on the bottom, and the barrier metal film 4 is shaped. Thus, when the tungsten plug 5 is buried in the contact hole 3 via the barrier metal film 4 in a later step, the void A
Is suppressed, the wiring film 6 formed thereon is suppressed.
Better step coverage.

Subsequently, as shown in FIG. 5, a tungsten film 5A having a thickness of about 5,000 to 10,000 is formed as a contact plug material on the barrier metal film 4 including the inside of the contact hole 3 by a PVD method. At this time,
Since the barrier metal film 4 on the contact hole 3 is shaped, the occurrence of void A in the conventional tungsten film 5A is suppressed.

Next, as shown in FIG. 6, the tungsten film 5A is etched back, and a tungsten plug 5 is buried in the contact hole 3 with a barrier metal film 4 interposed therebetween. Subsequently, a metal film made of an aluminum film or an aluminum alloy film having a thickness of about 4000 to 10,000 is formed on the entire surface including the tungsten plug 5 by a sputtering method or a PVD method, and the metal film is formed by a known patterning technique. Then, the wiring film 6 is formed by patterning. At this time, since the tungsten plug 5 is buried in the contact hole 3 via the barrier metal film 4 shaped as described above, generation of voids in the tungsten plug 5 is suppressed. The wiring film 6 formed on 5 has good step coverage.

As described above, according to the present invention, the tungsten plug 5 can be buried in the contact hole 3 by removing the overhanging portion of the barrier metal film 4A by Ar sputtering so that no void is generated in the contact hole 3.
Since the step coverage of the wiring film 6 formed thereon is improved, the present invention can be applied to a so-called stacked contact structure technology in which an upper contact hole is laminated on a lower contact hole, for example.

FIG. 8 is a sectional view for explaining an embodiment in which the present invention is applied to a nonvolatile semiconductor memory device having a floating gate. In FIG. 8, a source region 12 is provided on a surface layer of a P-type silicon substrate 11.
And drain region 13 are formed apart from each other. On the substrate 11 on both sides of the source region 12, a floating gate 15 made of a conductive polysilicon film having a thickness of about 1000 to 2000 is formed via an insulating film 14 having a thickness of about 100 to 200. ing. Further, the substrate 11 between the source region 12 and the drain region 13 has a thickness of about 300 ° to 40 °.
A polysilicon film having a thickness of about 1000 to 2000 mm and an insulating film 16 having a thickness of about 1000
Tungsten silicide (WS)
ix) A control gate 17 made of a film is formed. An end of the control gate 17 on the source region 12 side is disposed above the floating gate 15 with the insulating film 16 interposed therebetween.

The source region 12 and the control gate 17 both extend in one direction (perpendicular to the plane of the drawing). A plurality of drain regions 13 and a plurality of control gates 17 are provided on both sides of the source region 12. They are arranged along the one direction. Then, the control gate 17 functions as a word line of the nonvolatile semiconductor memory device.

On the silicon substrate 11, an interlayer insulating film 18 having a thickness of about 4000 to 6000 ° is formed so as to cover the floating gate 15 and the control gate 17.
The drain region 13 is in contact with the drain region 13 through a contact hole 19 opened to form a wiring film serving as a bit line of the nonvolatile semiconductor memory device.

Here, the contact hole 19 in which the above-mentioned wiring film is formed is formed in a high step portion of the nonvolatile semiconductor memory device in which the floating gate 15 and the control gate 17 are stacked as shown in FIG. Therefore, it is inevitable that the contact hole 19 becomes deeper, and when a wiring film made of aluminum or the like is formed in the contact hole 19, the step coverage deteriorates. Therefore, when the above-described tungsten plug is buried in the contact hole 19 and a wiring film is formed on the tungsten plug, the present invention is applied to improve the step coverage of the wiring film. The step coverage of the wiring film can be improved. That is, as shown in FIG. 8, the barrier metal film 2 is formed on the entire surface including the inside of the contact hole 19.
After forming 0, the barrier metal film 20 is sputtered with Ar ions and the surface of the barrier metal film 20 is beaten with Ar ions to cut the surface, as described in one embodiment.
In particular, the barrier metal film 20 formed in an overhang shape at the corner of the contact hole 19 is scraped off, the thickness of the barrier metal film 20 at the corner becomes thin, and the upper part of the contact hole 19 is tapered. And the shaved barrier metal film 20 is deposited again on the bottom, and the barrier metal film 20 is shaped. Thereby, when the tungsten plug 21 is buried in the contact hole 19 via the barrier metal film 20 in a later process, the void A
Is suppressed, the wiring film 2 formed thereon is suppressed.
The step coverage of No. 2 is improved. Thereafter, as in the case of the first embodiment, approximately 500 contact plug materials are formed on the barrier metal film 20 including the inside of the contact hole 19.
After a tungsten film having a thickness of 0 ° to 10,000 ° is formed by a sputtering method or a PVD method, the tungsten film is etched back, and a tungsten plug 21 is buried in the contact hole 19 via a barrier metal film 20. After a metal film made of an aluminum film or an aluminum alloy film having a thickness of about 4000 to 10,000 is formed on the entire surface including the tungsten plug 21 by a sputtering method or a PVD method, the metal film is patterned by using a well-known patterning technique. To form a wiring film 22. In this embodiment, an example is shown in which the present invention is applied to a so-called split gate type nonvolatile semiconductor memory device in which a control gate 17 is laminated on a part of a floating gate 15 with an insulating film 16 interposed therebetween. The present invention may be applied to a so-called stacked gate type nonvolatile memory device in which a control gate is stacked on the entire surface of a floating gate.

[0022]

As described above, according to the present invention, the surface of the barrier metal film is beaten with Ar ions by the Ar sputtering method so that the barrier metal film portion formed in an overhang shape particularly at the corner of the contact hole is formed. When the tungsten plug is buried through the barrier metal film in the contact hole, the thickness of the barrier metal film at the corners is reduced and the upper part of the contact hole is tapered. Since the generation of voids as in the prior art is suppressed, the step coverage of the wiring film formed thereon is improved.

Further, the present invention can be applied to a nonvolatile semiconductor memory device in which a floating gate and a control gate are stacked, such as a nonvolatile semiconductor memory device in which a tungsten plug is buried in a contact hole formed in a region having a high step portion. Since the voids generated in the tungsten plug can be suppressed, the step coverage of the wiring film formed thereon can be improved.

[Brief description of the drawings]

FIG. 1 is a first sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention;

FIG. 2 is a second cross-sectional view illustrating the method for manufacturing the semiconductor device according to one embodiment of the present invention;

FIG. 3 is a third sectional view illustrating the method for manufacturing the semiconductor device according to one embodiment of the present invention;

FIG. 4 is a fourth sectional view illustrating the method for manufacturing the semiconductor device according to one embodiment of the present invention;

FIG. 5 is a fifth sectional view illustrating the method for manufacturing the semiconductor device according to one embodiment of the present invention;

FIG. 6 is a sixth sectional view illustrating the method for manufacturing the semiconductor device according to one embodiment of the present invention;

FIG. 7 is a seventh sectional view illustrating the method for manufacturing the semiconductor device according to one embodiment of the present invention;

FIG. 8 is a cross-sectional view illustrating a method of manufacturing a semiconductor device according to another embodiment of the present invention.

FIG. 9 is a first cross-sectional view illustrating a conventional method for manufacturing a semiconductor device.

FIG. 10 is a second cross-sectional view showing the conventional method for manufacturing a semiconductor device.

FIG. 11 is a third cross-sectional view showing a conventional method for manufacturing a semiconductor device.

FIG. 12 is a fourth cross-sectional view illustrating the conventional method for manufacturing a semiconductor device.

FIG. 13 is a fifth sectional view showing the conventional method for manufacturing a semiconductor device.

Claims (3)

[Claims] 1. A method of manufacturing a semiconductor device, comprising: forming a contact plug in a contact hole selectively formed in an insulating film on a semiconductor substrate; and forming a wiring film on the contact plug. Forming an adhesive film on the insulating film, sputtering an impurity ion on the adhesive film by sputtering, and forming a contact plug material on the entire surface including the inside of the contact hole via the adhesive film. Etching a contact plug material to bury the contact plug in the contact hole; and forming a metal film on the contact plug and then patterning the metal film to form a wiring film. A method for manufacturing a semiconductor device. 2. A contact plug is formed in a contact hole formed in a region having a high step portion such as a nonvolatile semiconductor memory device in which a floating gate and a control gate are stacked, and a wiring film is formed on the contact plug. Forming a contact film in the contact hole and on the insulating film; a step of sputtering impurity ions on the contact film by a sputtering method; and Forming a contact plug material on the entire surface including the inside of the contact hole, etching back the contact plug material to bury the contact plug in the contact hole, and forming a metal film on the contact plug; Forming a wiring film by patterning the film. Production method. 3. The method according to claim 1, wherein the adhesion film is made of a titanium film, a titanium nitride film, or a laminated film of a titanium film and a titanium nitride film, and the impurity ions are argon ions. Of manufacturing a semiconductor device.