Method for Fabricating Semiconductor Device

Abstract

A method for fabricating a semiconductor device, in which a lifting phenomenon can be prevented from occurring in forming an amorphous carbon film on an etched layer having tensile stress. According to the invention, since a compression stress on the etched layer or the amorphous carbon film can be reduced or a compression stress film is formed between the etched layer or the amorphous carbon film to prevent a lifting phenomenon from occurring and thus another pattern can be formed to fabricate a highly integrated semiconductor device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the disclosure, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a sectional view showing an amorphous carbon film and a CVD tungsten film formed according to the prior art.

FIG. 2 is a sectional view showing a PVD tungsten film, a PE nitride film and an amorphous carbon film formed according to the prior art.

FIG. 3 is a sectional view showing a semiconductor device including a stacked layer of a HDP oxidation film, a CVD tungsten film and Ti—TiN film.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.

In the following, an embodiment of the invention will be described.

In a typical NAND flash memory process, a gate electrode is formed of a tungsten silicide (WSi), etc. and a nitride film and an interlayer insulation film are formed thereover and a stacked layer of a metal wire/a barrier metal layer and then a hard mask film is formed of a nitride film and an oxidation film, etc. At this time, when a PE-TEOS film is formed of the inter layer insulation film and a stacked layer of CVD tungsten film/Ti—TiN film is formed of the stacked layer, a lifting phenomenon occurs on the CVD tungsten film and the CVD tungsten film due to a tensile stress of the CVD tungsten film. Here, a stress concentration factor of the entire structure thereof is 0.67 MPa/m0.5.

Meanwhile, when the inter layer insulation film is formed of a HDP (High Density Plasma) oxidation film and a stacked layer of CVD tungsten film/Ti—TiN film is formed of the stacked layer, as shown in FIG. 3, a lifting phenomenon does not occur on the CVD tungsten film and the Ti—TiN film. At this time, a stress concentration factor of the entire structure thereof is 0.49 MPa/m0.5. Here, it is taught that when the stress concentration factor is large, the lifting phenomenon may occur, and that when the stress concentration factor is equal to or less than 0.49 MPa/m0.5, the lifting phenomenon does not occur on the CVD tungsten film.

Accordingly, when a stacked layer is formed by stacking films having tensile stress and further the tensile stress are reduced for the stress concentration factor of the stacked layer to be equal to or less than 0.49 MPa/m0.5, the lifting phenomenon is prevented from occurring. For this purpose, when an amorphous carbon film is stacked over an etched layer having a tensile stress, as a hard mask and a reflection preventing film, the tensile stress of the amorphous carbon film and the etched layer is to reduce, or a compression stress film having a compression stress is formed between the stacked layers and thus the lifting phenomenon can be prevented. Here, the etched layer is formed as a conductive layer; preferably, it may be one of CVD tungsten, aluminum, TiCl4-TiN and polysilicon.

Details of this embodiment will be as follows.

Embodiment 1

An amorphous carbon film having a compression stress is formed. Typically, the amorphous carbon film has a tensile stress of about 90 MPa at a forming temperature of 550° C. Here, when the amorphous carbon film is formed at below this temperature, preferably, 100° C.-400° C., the amorphous carbon film has a compression stress. For example, the amorphous carbon film is formed at 300° C., it has a tensile stress of about 330 MPa.

Accordingly, when an amorphous carbon film is formed over the etched layer, the amorphous carbon film is formed at a range of 100° C. to 400° C. and thus a lifting phenomenon on a stacked layer can be prevented. The following Table 3 shows stresses and stress concentration factors on a CVD tungsten film and an amorphous carbon film formed at 300° C., respectively, and a stress concentration factor on stacked layers formed by stacking them.

TABLE 3
Film	Thickness (Å)	Stress (dyn/cm2)	Kc (MPa/m0.5)
Amorphous carbon	2000	−3.30e+09	−0.215
film
CVD tungsten film	800	1.50e+10	0.619
Total Kc on the Stacked layer	0.404

Referring to Table 3, the stress concentration factor on the stacked layer is 0.404 MPa/m0.5, and thus a lifting phenomenon does not occur.

Embodiment 2

To reduce a tensile stress on an etched layer, a heat treatment process against the etched layer is performed. The heat treatment process for reducing a tensile stress on the etched layer is performed under an argon atmosphere at 300° C. to 500° C. for 0.5 hours to two hours, or under argon atmosphere at 300° C.-500° C. for one minute to 20 minutes through a Rapid Thermal Annealing process.

Embodiment 3

A film having a compression stress is formed between a stacked layer of an etched layer and an amorphous carbon film. The film having a compression stress includes a Plasma Enhanced nitride film, an oxide film, SiON film and a strontium oxide film (SrOx), etc. The following Table 4 shows stresses and stress concentration factors on a CVD tungsten film, an amorphous carbon film, and a PE nitride film respectively, and a stress concentration factor on stacked layers formed by stacking the PE nitride film between the CVD tungsten film and the amorphous carbon film.

TABLE 4
Film	Thickness (Å)	Stress (dyn/cm2)	Kc (MPa/m0.5)
Amorphous carbon	2000	9.00e+08	0.059
film
PE nitride film	300	−2.60+09	−0.066
CVD tungsten film	800	1.5e+10	0.619
Total Kc on the Stacked layer	0.338

Referring to Table 4, the stress concentration factor on the stacked layer is 0.038 MPa/m0.5, and thus a lifting phenomenon does not occur.

According to the method for fabricating a semiconductor device of the invention, when an amorphous carbon film is stacked as a hard mask and a reflection preventing film on a etched layer having a tensile stress, a lifting phenomenon does not occur and thus minute pattern can be formed. Accordingly, highly integrated and minute semiconductor can be fabricated.

Claims

1. A method of fabricating a semiconductor device comprising the steps of: forming an etched film on a semiconductor substrate; andforming an amorphous carbon film on the etched film, wherein when the etched film has a tensile stress, the amorphous carbon film has a compression stress.

2. A method of fabricating a semiconductor device according to claim 1, comprising forming the amorphous carbon film at 100° C. to 400° C.

3. A method of fabricating a semiconductor device according to claim 1, wherein the etched film is a conductive layer.

4. A method of fabricating a semiconductor device comprising the steps of: forming an etched layer having a tensile stress on a semiconductor substrate;depositing an amorphous carbon film on the etched layer; andperforming a heat treatment to eliminate the tensile stress on the etched layer.

5. A method of fabricating a semiconductor device according to claim 4, comprising performing the heat treatment under an argon atmosphere at 300° C. to 500° C. for 0.5 hours to two hours.

6. A method of fabricating a semiconductor device according to claim 4, comprising performing the heat treatment under an argon atmosphere at 300° C. to 500° C. for one minute to 20 minutes through a Rapid Thermal Annealing process.

7. A method of fabricating a semiconductor device according to claim 4, wherein the etched layer is a conductive layer.

8. A method of fabricating a semiconductor device comprising the steps of: forming an etched layer on a semiconductor substrate;forming a compression stress film having a predetermined compression stress on the etched layer; anddepositing an amorphous carbon film on the compression stress film, wherein the tensile stress on the amorphous carbon film can be reduced due to the compression stress on the compression film.

9. A method of fabricating a semiconductor device according to claim 8, wherein the compression stress film comprises at least one of a PE nitride film, an oxide film, an SiON film, and a strontium oxide film (SrOx).

10. A method of fabricating a semiconductor device according to claim 8, wherein the etched layer is a conductive layer.

11. A method of fabricating a semiconductor device according to claim 10, comprising forming the conductive layer of one of Chemical Vapor Deposition (CVD) tungsten, aluminum, TiCl4-TiN, and polysilicon.