JPS6286726A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To form patterns with excellent reproducibility by making the head shape of resist patterns rectangular by a method wherein the surface layer of resist layer is made low-sensitive to developer to decelerate the melting speed of surface layer. CONSTITUTION:A substrate 1 is coated with resist to form a resist layer 2 with even film thickness. First, the surface layer 7 only of resist layer 2 is heated to be made low-sensitive and insoluble and then the regions 4 to be removed are irradiated with ultraviolet rays 3. Second, the irradiated parts 4 are melted by immersing the resist layer 2 in developer 5 such as alkali, etc. At this time, not-yet-irradiated regions of the surface layer 7 are left almost as they are since the melting speed of the low-sensitive surface layer 7 in the developer 5 is decelerated to make the head shape of finished patterns 8 rectan gular. Besides, such a shape to be repeated on every formation of resist patterns 8 can improve the reproducibility of the finished patterns 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of forming a resist pattern on a substrate in the manufacturing process of semiconductor devices and the like.

[Prior Art] FIG. 2 is a diagram showing a conventional resist 1 pattern forming method.

Next, a conventional resist pattern forming method will be explained with reference to FIG. As shown in FIG. 2(1), a resist is applied onto a substrate by a spin method or the like to obtain a resist 11!2 having a uniform thickness.

Subsequently, the area 4 that needs to be removed is irradiated with ultraviolet rays 3.

Subsequently, as shown in FIG. 2 (II), the substrate 1 coated with the resist layer 2 is immersed in a developer 5. As a result, the irradiated area 4 is dissolved in the developer 5, and a resist pattern 6 as shown in FIG.

[Problem to be solved by the invention 1] In the conventional resist pattern forming method, as shown in FIG. Since the solution continues to be in contact with the developer until the dissolution of
The boundary region 41 shown in > is slightly dissolved. Therefore, the head shape of the formed resist pattern is not rectangular but rounded as shown in FIG. 2 (I[[).

Since the degree of dissolution of the unexposed areas differs depending on the formation of the resist pattern, a problem arises in the reproducibility of the finish. It also has an adverse effect on the dry etching that follows. That is,
During dry etching, the resist pattern is also slightly etched, but because the shape of the resist pattern is rounded, the width of the pattern shown by arrow A in Figure 2 (I [[)] changes due to this etching. , desired M
There is a problem of not being able to obtain a degree.

Therefore, the present invention has been made to solve the above-mentioned problems, and aims to make the head shape of a resist pattern rectangular and to obtain a pattern with good reproducibility.

[Means for Solving the Problems] In the resist pattern forming method according to the present invention, a first resist layer is provided on a substrate in a first step, and a second resist layer is formed on a substrate.
In the step, a second resist layer having a lower dissolution rate than the first resist layer in the developer is provided on the first resist layer, and in the third step, the first and second resist layers are disposed on the first resist layer.
The resist layer is exposed to light, and in a fourth step, the exposed first and second resist layers are developed with a developer.

[Operation] The second step provided by the second step in this invention
Since the resist layer remains as the head of the resist pattern during the development process, a pattern that maintains a rectangular shape can be obtained.

[Example] Hereinafter, an example of an IM according to the present invention will be explained with reference to the drawings. FIG. 1 is a diagram showing a resist pattern forming method according to an embodiment of the present invention. Next, a resist pattern forming method according to an embodiment of the present invention will be described with reference to FIG.

As in the conventional example, a resist is applied onto a substrate 1 by a spin method to form a resist layer 2 having a uniform thickness. next,
Only the surface WI7 of the resist 1!2 shown in FIG. 1(I) is heated to make the surface layer 7 low in sensitivity and resistant to dissolution, and then removed as shown in FIG. 1(If). A necessary steel area 4 is irradiated with ultraviolet light 3. Next, as shown in FIG.
: Dissolve the irradiation part 4. At this time, since the surface layer with low sensitivity has a low dissolution rate in the developer, the surface W
J7 unirradiated l! ! Since the Ili region remains almost unchanged, the head shape of the finished resist pattern 8 becomes rectangular as shown in FIG. 1 (iV). Moreover, since such a shape can be obtained as the same shape every time a resist pattern is formed, the reproducibility of the finish is improved.

This has a positive effect on subsequent dry etching. In other words, even if the surface of the resist pattern is slightly etched by the dry etching that follows this process,
The width of the pattern remains almost the same.

In the above-mentioned embodiment, the sensitivity of the surface layer is lowered by a thermal reduction method to reduce the sensitivity to 1J! Although the dissolution rate for a 1 m liquid is reduced, the present invention is not limited to this, and a resist layer with low sensitivity may be applied to the surface layer of the resist.

[Effects of the Invention] As described above, according to the present invention, the surface layer of the resist layer is made to have low sensitivity to the developer so that the dissolution rate is low, so that the top of the resulting resist pattern is Since the shape can be made into a rectangle, the reproducibility of the finish is improved, which has a positive effect on the subsequent dry etching.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a resist pattern forming method according to an embodiment of the present invention. FIG. 2 is a diagram showing a conventional resist pattern forming method. In the figure, 1 is a substrate, 2 is a resist layer, 3 is an ultraviolet ray,
Reference numeral 4 indicates an ultraviolet irradiation section, 5 indicates a developer, 6 indicates a resist pattern, 7 indicates a desensitized resist surface layer, and 8 indicates a resist pattern according to the present invention. In addition, in the figures, the same symbols indicate the same or equivalent parts.
. Agent Masu Oiwa Figure 1

Claims (3)

[Claims] (1) A method for forming a resist pattern on a substrate in the manufacture of semiconductor devices, etc., comprising: a first step of providing a first resist layer on the substrate; a second step of providing a second resist layer having a lower dissolution rate on the first resist layer; a third step of exposing the first and second resist layers; and a third step of exposing the first and second resist layers to light. and a fourth step of developing the second resist layer with a developer, and leaving a pattern head shape in a rectangular shape during resist pattern formation. (2) The resist pattern forming method according to claim 1, wherein the second resist layer is formed by heating a surface layer of the first resist layer. (3) The resist pattern according to claim 1, wherein the second resist layer is formed by applying a resist solution with a low dissolution rate onto the first resist layer. Formation method.