JPH0529280A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method where a resist pattern excellent in shape accuracy is formed on a workpiece without complicated processes, and a pattern is accurately formed on the workpiece using the resist pattern as a mask. CONSTITUTION:A silicon monoxide film 3 is formed on a workpiece 2, then a resist film 4 is formed on the silicon monoxide film 3, the resist film 4 is exposed to light and developed into a resist pattern, the silicon monoxide film 3 and the workpiece 2 are etched through the resist pattern concerned as a mask to form a pattern on the workpiece 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for forming a pattern on a workpiece, and more particularly to a method for accurately forming a resist pattern used as an etching mask.

[0002]

2. Description of the Related Art Traditionally, a resist film is formed on an object to be processed, a mask is used to selectively expose and develop the resist film to form a resist pattern, and the resist pattern is used as a mask. A method of etching a work piece to form a pattern is used, but there is a problem in that the shape of the resist pattern cannot be accurately formed due to the influence of reflected light from the work piece. As a means for solving the problem, improvement measures have been taken to absorb the reflected light by adding a dye to the resist material or increasing the film thickness of the lower resist film by using a multilayer resist method.

[0003]

However, when a dye-containing resist material is used, there is a drawback that the shape accuracy of the resist pattern after exposure and development is lowered and the resolution is also lowered. Further, when the multi-layer resist method is used, the throughput is reduced as the process becomes complicated, and it is not suitable for a mass production process.

An object of the present invention is to eliminate this drawback, and a resist pattern having a good shape accuracy is formed on the object to be processed without complicated steps, and this is used as a mask to form a pattern on the object to be processed. The object is to provide a method for forming a high precision.

[0005]

The above object is to form a silicon monoxide film (3) on a workpiece (2) and to form a resist film (4) on the silicon monoxide film (3). Then, the resist film (4) is selectively exposed and developed to form a resist pattern (41), and the silicon monoxide film (3) and the workpiece are processed using the resist pattern (41) as a mask. This is achieved by a method for manufacturing a semiconductor device, which includes a step of etching the body (2) to form a pattern on the body (2) to be processed. The silicon monoxide film (3)
The film thickness of is preferably 300 Å or more.

[0006]

Function: The work piece is made of tungsten silicide (WS
The case of i _x ) film will be described as an example. Tungsten silicide (WSi _x), silicon monoxide (SiO) and resist the wavelength 365nm of (i line) light and the wavelength 248 nm (Kr
Table 1 shows the refractive index n and the absorption coefficient k for the light of F).

[0007]

[Table 1] As shown in FIG. 2, the absorber 6 having a refractive index n and an absorption coefficient k.
Assuming that the intensity of light reflected from the interface between the resist film 4 and the absorber 6 when the resist film 4 is formed _{thereon and} the light having the intensity I _o is vertically incident thereon is I, I / I _o is intensity reflection at the interface. Call the rate. Graphs of this intensity reflectance as a function of the refractive index n and the absorption coefficient k of the absorber are shown in FIGS. 3 and 4. FIG. 3 is for light with a wavelength of 248 nm (KrF), and FIG. 4 is for light with a wavelength of 365 nm (i-line).

The reflectance from the interface with the resist film 4 when the absorber 6 is silicon monoxide (SiO) having the refractive index n and the absorption coefficient k shown in Table 1 is obtained from FIGS. 3 and 4. And is several percent for both wavelengths of 248 nm and 365 nm, which is extremely small. On the other hand, the absorber 6 is shown in Table 1.
The reflectance from the interface between the resist film 4 when it is a tungsten silicide having a refractive index n and absorption coefficient k (WSi _x) shown in, and obtained from FIGS. 3 and 4 which, in the light of any wavelength On the other hand, it will be as large as about 30%.

[0009] This is as shown in FIG. 1 (b), of tungsten silicide (WSi _x) workpiece 2
While the reflectance from the interface between the resist film 4 and the workpiece 2 is as high as about 30% when the resist film 4 is directly formed on the workpiece 2, as shown in FIG. It is shown that the amount of reflection from the interface between the resist film 4 and the silicon monoxide (SiO) film 3 when the resist film 4 is formed on the silicon monoxide (SiO) film 3 is extremely small.
The light that has entered the film without being reflected by the surface of the silicon monoxide (SiO) film 3 is absorbed by the silicon monoxide (SiO) film 3 and reflected from the workpiece 2 formed thereunder. Is almost gone.

Although silicon monoxide (SiO) becomes silicon dioxide (SiO ₂ ) when exposed to air, the antireflection effect is sufficiently recognized even in this case.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pattern forming method according to an embodiment of the present invention will be described below with reference to the drawings.

[0012] As shown in FIG. 5 (a), will be described as an example the case of forming a 0.2μm thick tungsten silicide (WSi _x) pattern film 2 formed as a workpiece on the substrate 1 . First, using the sputtering method,
Tungsten silicide (WSi _x) film 2 on to form the silicon monoxide (SiO) film 3 to about 300Å thick, then
The resist film 4 is applied to a thickness of about 0.8 μm, and the reticle 5 is used to selectively expose the resist film 4.

As shown in FIG. 5B, the resist film 4 is developed to form a resist pattern 41. As shown in FIG. 6A, the silicon monoxide (SiO) film 3 is etched using the resist pattern 41 as a mask using a reactive ion etching method using carbon tetrafluoride as a reaction gas.

[0014] As shown in FIG. 6 (b), halogen-based gas (e.g. fluorine, chlorine, etc.) using a reactive ion etching method using a reactive gas or the like, a tungsten silicide (WSi _x) film 2 is etched To form a pattern.

As shown in FIG. 6C, the resist pattern 41 is removed by using the oxygen plasma etching method.
Since the silicon monoxide (SiO) film 3 is an insulating film, it may be possible to proceed to the next step with the film attached.
If the silicon monoxide (SiO) film 3 needs to be removed, it is removed by etching using a reactive ion etching method using carbon tetrafluoride or the like as a reaction gas.

[0016]

As described above, in the method of manufacturing a semiconductor device according to the present invention, by interposing the silicon monoxide film between the object to be processed and the resist film, the object to be processed at the time of exposure is removed. Since it can prevent reflection,
The resist pattern can be accurately formed without involving complicated steps, and it greatly contributes to miniaturization and mass production of semiconductor devices.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of reflectance.

FIG. 3 is a graph showing the reflectance at the interface between the resist and the absorber as a function of the refractive index and the absorption coefficient of the absorber (when λ = 248 nm).

FIG. 4 is a graph showing the reflectance at the interface between the resist and the absorber as a function of the refractive index and the absorption coefficient of the absorber (when λ = 365 nm).

FIG. 5 is a pattern forming process diagram (1) according to the present invention.

FIG. 6 is a pattern forming process diagram (2) according to the present invention.

[Explanation of symbols]

1 substrate 2 Workpiece 3 Silicon monoxide film 4 Resist film 41 Resist pattern 5 reticle 6 absorber

Claims (2)

[Claims] 1. A silicon monoxide film (3) is formed on a workpiece (2), a resist film (4) is formed on the silicon monoxide film (3), and the resist film (4) is formed. A resist pattern (41) is formed by selectively exposing and developing, and the silicon monoxide film (3) and the object to be processed (2) are etched by using the resist pattern (41) as a mask. A method of manufacturing a semiconductor device, comprising a step of forming a pattern on a processed body (2). 2. The film thickness of the silicon monoxide film (3) is 30.
The method for manufacturing a semiconductor device according to claim 1, wherein the value is 0Å or more.