JPH0547706A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the level difference between the tungsten film and the insulating film at a contact part, in the structure where only the contact hole is plugged with a tungsten film, what is called a tungsten plug structure. CONSTITUTION:A process of lightening the step between the tungsten film 4 and the insulating film 2 inside a contact hole by etching back an oxide film is performed after the process of plugging the contact hole with a tungsten film 4 and processing it into plug shape by etchback, and then a process of forming wiring by a metallic film 5 is performed. Hereby, the flatness in the contact hole improves, and the reliability on the covering metallic wiring improves.

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.

[0002]

2. Description of the Related Art As semiconductor devices become highly integrated and miniaturized,
In the contact hole that connects the wiring layers,
The ratio of height to diameter, so-called aspect ratio, is increasing. Therefore, when connecting the metal wiring through the contact hole portion, the step coverage performance is poor by the conventionally used sputtering method, the sputtered film is not formed thick at the bottom of the contact hole, and the semiconductor device due to poor connection is formed. There is a possibility that the reliability of the may deteriorate. As one of the measures to avoid this problem, a contact hole is filled with a tungsten film formed by a chemical vapor deposition method (hereinafter, referred to as a CVD method) having an excellent step coverage performance, and interconnections between wirings are formed through the tungsten film. The method of taking is taken.

2 (a) to 2 (e) are cross-sectional views showing steps of filling a contact hole in a tungsten film by a conventional method. In the figure, 1 is a semiconductor substrate, 2 is an insulating film, 3 is an adhesion film, 4 is a tungsten film, and 5 is a metal sputter film.

Next, the operation will be described. First, FIG.
As shown in (a), after forming the insulating film 2 on the semiconductor substrate 1, a contact hole is opened by photolithography and processing techniques.

Next, as shown in FIG. 2B, a conductive film for preventing peeling of the tungsten film, a so-called adhesion film 3 (for example, a titanium nitride film) is formed.

Next, as shown in FIG. 2 (c), a tungsten film 4 is deposited by the CVD method to fill the contact hole.

Next, as shown in FIG. 2D, the tungsten film 4 and the adhesion film 3 are etched back to leave the tungsten film 4 and the adhesion film 3 in the form of a plug only in the contact holes (hereinafter, this structure will be described). Is called a tungsten plug). At this time, if the etch back amount is insufficient, the tungsten film 4 or the adhesion film 3 remains as a residue on the insulating film 2 and causes a short circuit between wirings. Therefore, some excess etch-back is required to allow a process margin.

Finally, as shown in FIG. 2 (e), a metal sputtered film 5 is deposited by a sputtering method and processed into a wiring shape by a photoengraving technique and a machining technique.

[0009]

According to the conventional method, since the tungsten film 4 recedes into the contact hole when excessive etching back is performed in the step of etching back the tungsten film 4 as described above, A step is formed between the tungsten films 4. Since the metal sputtered film 5 coated on it has poor step coverage, there is a problem that the film thickness becomes thin at this step, and reliability characteristics such as electromigration resistance are deteriorated.

The present invention has been made to solve the above problems, and it is possible to reduce the step between the insulating film and the tungsten film in the contact hole portion and improve the reliability of the metal wiring. An object of the present invention is to obtain a method of manufacturing a semiconductor device that can be manufactured.

[0011]

A method of manufacturing a semiconductor device according to the present invention includes a step of etching back an insulating film on a substrate after forming a tungsten plug.

[0012]

In the method of manufacturing a semiconductor device according to the present invention, by etching back the insulating film, the level difference between the insulating film and the tungsten film in the contact hole portion is reduced, and a flat metal sputtered film is obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 (a) to 1 (d) are cross-sectional views by process for explaining a method of manufacturing a semiconductor device according to an embodiment of the present invention. It should be noted that the same or corresponding parts as those in FIG. 2 are denoted by the same reference numerals.

First, as shown in FIG. 1A, similarly to the conventional method, an insulating film 2 is formed on a semiconductor substrate 1, a contact hole is opened, and then an adhesion film 3 (for example, a titanium nitride film) is formed. ) Is formed. Further, a tungsten film 4 is deposited by the CVD method to fill the contact hole.

Next, as shown in FIG. 1B, the tungsten film 4 and the adhesion film 3 are etched back to form a tungsten plug.

Next, as shown in FIG. 1C, the insulating film 2 is etched back. At this time, for example, CF ₄ , CHF ₃
If reactive etching using a gas system having a high selection ratio with respect to tungsten is used, the tungsten film 4 in the contact hole is hardly etched and only the insulating film 2 is etched. With proper etching conditions,
It is possible to almost eliminate the step between the tungsten film 4 and the insulating film 2 in the contact hole portion.

Finally, as shown in FIG. 1D, a metal sputtered film 5 (for example, an aluminum film) is deposited by a sputtering method and processed into a wiring shape.

According to the present embodiment as described above, by performing the reactive etching with a high selection ratio between the tungsten film and the insulating film, it is possible to selectively etch the insulating film and eliminate the step between the two. Therefore, it becomes easy to obtain a flat metal wiring, and the reliability is improved.

[0019]

As described above, according to the method of manufacturing the semiconductor device of the present invention, the contact hole is filled with the tungsten film, the tungsten plug is formed by etching back, and then the insulating film is etched back to contact hole. Since the flatness between the tungsten film and the insulating film in the portion is significantly improved, there is an effect that the reliability of the metal wiring covering the surface can be improved.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view for each step showing a method for manufacturing a semiconductor device by a conventional method.

[Explanation of symbols]

 1 Semiconductor substrate 2 Insulating film 3 Adhesion film 4 Tungsten film 5 Metal sputter film

Claims (1)

[Claims] 1. A step of forming an insulating film on a semiconductor substrate, a step of forming a contact hole in the insulating film, a step of forming a conductive film on the insulating film, and a step of chemically forming on the conductive film. A step of depositing a tungsten film by a vapor deposition method to fill the contact hole; a step of etching back the conductive film and the tungsten film to leave the conductive film and the tungsten film only in the contact hole; A method of manufacturing a semiconductor device, comprising: a step of etching back the tungsten film by etching having a high selection ratio; and a step of thereafter depositing a metal film by a sputtering method.