JPS63299336A - Pattern formation - Google Patents

Abstract

PURPOSE:To form a resist pattern with a high aspect ratio and high resolution, by coating a substrate with photosensitive resin, prebaking it, irradiating it with far-ultraviolet rays, performing a desired pattern exposure, and developing it. CONSTITUTION:After a positive photosensitive resin 2 is spread on a semiconductor substrate 1, and subjected to hot plate baking, a resist firm 2 is obtained. The whole part of the resist film 2 is irradiated with far-ultraviolet rays 3. A desired pattern is exposed, via a mask 4, by a reduction projection aligner. A resist pattern 2A is formed, by paddle developing of 60 sec. applying alkali developer. Thereby, the pattern 2A is formed with a high aspect ratio and high resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for forming resist patterns for semiconductor devices, etc.

2. Description of the Related Art As semiconductor device manufacturing becomes finer, methods are being devised to improve the shape and resolution of resist patterns.

Among these, a pattern forming method that involves irradiating deep ultraviolet rays after pattern exposure and then developing has recently attracted attention as a simple method in terms of process (Y, 0kuda at
al,, Proceeding Ops BII (P
roc, of 5PIE), 771-42).

According to this method, the development speed ratio between the upper and lower parts of the resist is increased by irradiation with far ultraviolet rays, so that the shape and resolution of the pattern are said to be improved.

However, as a result of research conducted by the inventors, it has been found that in such a conventional method, variations in dimensional accuracy tend to occur when patterns have different dimensions.

The conventional method will be explained using FIG.

A positive photosensitive resin (MPS manufactured by Sibley Co., Ltd.) is placed on the semiconductor substrate 1.
1400-27) and after hot plate baking for 90'02 minutes, a resist film 2 with a thickness of 1.2 μm was obtained (
Figure 3(a), ).

Next, use a reduction projection exposure device manufactured by Kotsu Co., Ltd. with NA = 0.42.
A desired pattern is exposed to light (wavelength: 43 nm) through the stripe mask 4 (FIG. 3(b)). Next, in a heated state of semiconductor substrate 1 gold 100'0K7Jllll, deep ultraviolet 2 (1~320nm; 10mW/m at 220nm) t'
It was irradiated for 5 seconds (Fig. 3(C)). Thereafter, pattern 2B=i was formed by paddle development for 60 seconds using an alkaline developer named Sibley Co., Ltd. MF-319 (FIG. 3(d)).

The obtained resist pattern 2B has a high aspect ratio (the value obtained by dividing the top side by the bottom side of the resist pattern) of 0.9, and a resist pattern film reduction of 0.05.
It was a good pattern of less than μm.

However, in pattern 2B, a pattern with a mask dimension of 1.0 .mu.m is 1.16 .mu.m, and a pattern with a mask dimension of 0.6 .mu.m is 0.7 .mu.m, so that the mask dimension and the actual pattern dimension are greatly different. That is, a phenomenon has occurred in which the actual pattern size is generally 10% or more larger than the mask size. This is thought to be because the end portion of the alkaline developer dissolving portion, which is the pattern exposure portion, is inactivated by deep ultraviolet rays, that is, rendered insoluble in alkali.

To explain this with reference to FIG. 4, when the pattern-exposed portion 100 is irradiated with far ultraviolet rays, an insolubilization phenomenon occurs but a portion 110 that is sufficiently soluble in alkali and a cine-solubilized portion 120 are formed by the far ultraviolet rays. . The insolubilization in alkali is thought to be due to the fact that ketene in the photoreceptor produced by pattern exposure is polymerized or decomposed by deep ultraviolet rays, resulting in a structure that is never decomposed by a subsequent alkaline developer. The above chemical reaction mechanism is shown below. Insoluble in retaining liquid Problems to be solved by the invention This phenomenon of alkali insolubility in the pattern exposed area due to far ultraviolet irradiation is seen throughout the pattern exposed area, but As shown in FIG. 4, the pattern ends tend to form an alkali insoluble mechanism in a chain with the unexposed parts of the pattern, so they are not completely insoluble in the alkaline developer, resulting in pattern size variations.

Such variations in pattern dimensions have been a major problem in practice since they reduce the yield of devices.

An object of the present invention is to derive a method that allows a resist pattern to have good shape resolution without dimensional variation.

Means for Solving All Problems The present invention is a pattern forming method characterized by performing pattern exposure after irradiation with deep ultraviolet rays, in order to solve the problems of conventional pattern forming methods.

Function: By irradiating the entire surface of the positive-type photosensitive resin with deep ultraviolet rays, an insolubilization phenomenon occurs in an alkaline developer based on the principle described in the conventional technology. However, by subsequently performing pattern exposure, the photoreceptor that has not reacted to the deep ultraviolet rays is exposed to light, and this exposed area eventually becomes alkali-soluble.

According to the method of the present invention, the pattern dimensions are ultimately controlled by the exposure dose of the last pattern exposure, so accurate "turn dimension management" can be performed.Of course, it is possible to improve the pattern shape and achieve high resolution. This property can be achieved by increasing the development speed ratio between the upper and lower parts of the resist by exposure to deep ultraviolet light, which is similar to the principle of the conventional method.

Note that if too much deep ultraviolet rays are applied, the photoreceptor will completely react and a pattern cannot be formed by subsequent pattern exposure, so the amount of photoreceptor reacting at the top and bottom of the resist will be about 6Q% or less. It is desirable to irradiate with far ultraviolet rays.

EXAMPLE The pattern forming method of the present invention will be explained with reference to FIG. Positive type on semiconductor substrate 1! Apply a photosensitive resin (resist) 2 (for example, Sibley MPS1400-27), and after baking on a hot plate for 2 minutes at 90°C, 1.2μ
A resist film 2 having a thickness of m was obtained (FIG. 1(a)). next,
Far ultraviolet rays 3 (190 to 320 nm;
10 mW101) f o at 220 nm,
After irradiation for a second (FIG. 1(b)), a desired pattern is exposed to a reduction projection exposure device using a NA O, 42 wavelength 436 nm manufactured by Kon Co., Ltd. Figure (C)).

After this, Shiba Turn 2A was formed by paddle development for 60 seconds using an alkaline developer called Sibley's MF-319 (
Figure 1 (→).

The obtained pattern 2A has a high aspect ratio of 0.9 and a resist pattern film reduction of 0.06β.
It was a good pattern of less than m.

Also, the pattern dimension mo in pattern 2A, the mask dimension is 1
．． The 0 μm pattern is 1.01 μm, and the mask size is 0.
A high dimensional controllability of 0.599 μm was maintained for the 6 μm pattern.

FIG. 2 is a detailed explanation of the present invention, and shows that even if a portion 10 where a cine dissolution phenomenon occurs due to deep ultraviolet irradiation,
Due to pattern exposure, this portion of the unexposed photoreceptor is exposed to light and becomes an alkali-solubilized portion, which is completely removed by an alkaline developer.

A similar effect can be obtained by heating the substrate during deep ultraviolet irradiation.
249nm), ArF (193nm), Xe
C1 (aoaam)) and high power, it can be processed in a very short time and is effective.

Furthermore, the amount of exposure for pattern exposure in the present invention has a balance with the amount of deep ultraviolet irradiation, but it is approximately 10 to 20% higher than that for pattern formation using a conventional method.

Effects of the Invention As described above, according to the method of the present invention, resist pattern formation can be performed with a high aspect ratio and high resolution, and the pattern dimensions can be easily controlled, leading to an improvement in the yield rate of semiconductor device manufacturing. It has high industrial value.

[Brief explanation of the drawing]

FIG. 1 is a process sectional view showing an embodiment of the pattern forming method of the present invention, FIG. 2 is an explanatory view of the effect of preventing pattern dimension variation by this method, and FIG. 3 is a process sectional view showing a conventional pattern forming method. , FIG. 4 is an explanatory diagram of pattern dimension variation according to the conventional method. 1...Semiconductor substrate, 2...Positive photosensitive resin, 3...Deep ultraviolet rays, 4...Mask, 5...Ultraviolet rays (4aenm), 6
T --- groaning fever (100'C), 2A --
-----Resist pattern. Name of agent: Patent attorney Toshio Nakao and one other person℃
fart

Claims (2)

[Claims] (1) A pattern forming method in which a photosensitive resin is applied onto a substrate, prebaked, irradiated with deep ultraviolet rays, and then exposed to a desired pattern and developed. (2) The pattern forming method according to claim 1, wherein the far ultraviolet rays are light oscillated from a XeCl, KrF or ArF excimer laser.