JP2000182940A - Method of forming resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold the cross sectional shape of a resist film nearly vertically and provide a satisfactory heat resistance by radiating ultraviolet rays on the developed resist film being heated. SOLUTION: (S1) A substrate is coated with a resist to form a resist film having a desired thickness, and (S2) exposed through a mask having a desired pattern. (S3) The resist film is developed with a specified developing liq. and (S4) heat treated at about 100 deg.C as the post-baking after developing. (S5) The UV irradiation is made with heating at a temp. of 100-200 deg.C, and (S6) the substrate is etched with the resist pattern thus formed as a mask. The heating temp. of 100-200 deg.C during the UV irradiation is on account of the heat resistance to the etching temp.; a lower temp. than 100 deg.C is not enough to obtain the shape stability effect but a higher temp. than 200 deg.C is not used for the etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a resist pattern. More specifically, the present invention relates to improvement of a resist pattern shape.

[0002]

2. Description of the Related Art In a photolithography process for manufacturing a semiconductor device, the type and thickness of a resist to be used are properly used depending on the type and thickness of a film to be etched. In a conventional general resist pattern forming method, a resist is applied to the surface of a substrate to form a resist film. Through a mask (or reticle) having a desired pattern on this resist,
Expose. Then, the resist film was developed with a developer to form a resist pattern.

[0003]

However, the side surface of the resist pattern after development is required to have a cross-sectional shape that is nearly vertical, but the exposure amount on the substrate side of the resist film is smaller than that on the surface of the resist film. Therefore, the cross section is formed so as to spread to the substrate side. In addition, in order to obtain resistance to heat during the subsequent etching, the resist film is subjected to heat treatment (post-baking). Even at this time, the heat deforms the resist film so that the cross section spreads to the substrate side. Further, when etching, the heat (usually 100 ° C. to 200 ° C.)
C), the cross section is deformed. In particular, when the resist pattern is thick (2 μm to 3 μm) and large, such deformation of the cross-sectional shape is remarkable.

As described above, when the cross-sectional shape of the side surface of the resist pattern is deformed so as to expand toward the substrate, and the inclination of the side surface of the pattern is increased, high-precision patterning cannot be performed.
In addition, it becomes difficult to set etching conditions, and control becomes difficult. In order to solve this problem, it is necessary to make the cross-sectional shape of the resist vertical and uniform so as to have heat resistance. As a method of improving the heat resistance, UV irradiation (UV curing) is generally performed before etching, but no effect of improving the resist shape has been reported.

Attempts have been made to lower the post-bake temperature to prevent deformation due to heat, but no significant effect has been obtained.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned prior art, and has as its object to provide a method of forming a resist pattern capable of maintaining a cross-sectional shape of a resist film nearly perpendicular and having sufficient heat resistance. I do.

[0007]

According to the present invention, there is provided a resist pattern forming method for forming a resist film on a substrate, exposing the resist film and developing the resist film. It is characterized by irradiating ultraviolet rays while heating.

According to this structure, the cross section of the resist film after the development and the heat treatment has a nearly vertical shape, and the change in the resist shape is suppressed even in the subsequent etching process.

In a preferred configuration example, the heating temperature is 100 ° C. or more and 200 ° C. or less.

According to this structure, the resist film after development and heat treatment can be more effectively irradiated by irradiating ultraviolet rays at a heating temperature of 100 ° C. or more and 200 ° C. or less, which is a temperature corresponding to a normal etching temperature condition. The cross section can be made almost vertical, and the change in the resist shape is suppressed even in the subsequent etching process.

[0011]

FIG. 1 is a flowchart of a method for forming a resist pattern according to an embodiment of the present invention.
First, a resist is applied to a substrate to form a resist film having a desired film thickness (step S1). Next, exposure is performed through a mask having a desired pattern (step S2). Thereafter, the resist film is developed with a predetermined developing solution (step S3). Heat treatment as post bake after development
This is performed at about 0 ° C. (step S4). Next, 100 ° C ~ 2
UV irradiation while applying a temperature of 00 ° C. (Step S
5). The substrate is etched using the resist pattern thus formed as a mask (step S6).

The reason why the heating temperature at the time of UV irradiation in step S5 is set to 100 ° C. to 200 ° C. is to take into consideration the heat resistance of the temperature at the time of etching. This is because the effect of (1) cannot be obtained, and the temperature of 200 ° C. or higher is a high temperature not used in etching. Within this temperature range, an appropriate heating temperature is set in consideration of an etching temperature condition, a processing time, and the like.

FIG. 2 shows the resist after development and U after development.
It is the figure which compared the resist shape irradiated with V, (A) is sectional drawing of a small pattern, (B) is a large pattern.
In each of (A) and (B) figures, the upper figure shows the resist film after development, and the lower figure shows the resist film irradiated with UV according to the present invention.

As shown in the figure, when the resist has a small pattern as shown in FIG. 2A, the resist film 2 on the substrate 1 is in contact with the side surface 3 of the developed resist film 2 even when the UV irradiation according to the present invention is performed. The difference is small. However, in the case where the resist has a large pattern as in (B), when the UV irradiation is performed, the side surface 3 becomes closer to the vertical than the developed shape. That is, as the pattern shape becomes larger, the effect of making the side surface 3 of the resist film 2 close to vertical by UV irradiation becomes larger.

[0015]

As described above, in the present invention, by irradiating ultraviolet rays while performing appropriate heat treatment,
The cross section of the resist film after the development and the heat treatment has a nearly vertical shape, and the change in the resist shape is suppressed even in the subsequent etching process. Thereby, especially when a large pattern having a large film thickness is formed, the side surface of the resist pattern is stably maintained in a nearly vertical shape, so that highly accurate patterning can be performed.

[Brief description of the drawings]

FIG. 1 is a flowchart of a method for forming a resist pattern according to an embodiment of the present invention.

FIGS. 2A and 2B are cross-sectional views of a small pattern and a large pattern of a resist after development and a resist irradiated with UV light after development.

[Explanation of symbols]

 1: substrate, 2: resist film, 3: side surface.

Claims (2)

[Claims] 1. A resist pattern forming method for forming a resist film on a substrate, exposing the resist film and developing the resist film, wherein the resist film after the development is irradiated with ultraviolet rays while being heated. Method. 2. The method according to claim 1, wherein the heating temperature is 100 ° C. or more and 200 ° C. or less.