JPH09213603A - Method of forming resist pattern - Google Patents

Abstract

(57) Abstract: In forming a resist pattern, the present invention provides:
The purpose is to make the pattern finer by swelling the resist. A method for forming a resist pattern on a substrate includes a step of applying a resist on the substrate, a step of exposing the resist, a step of developing the resist, and a step of combining the resist with an organic amine. . According to the present invention, it is possible to miniaturize a pattern without causing deterioration of the resist shape and independent of the pattern density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resist pattern, and more particularly to a method for forming a pattern made of a photoresist which is used as an etching mask, an ion implantation mask or the like on a substrate to be processed such as a semiconductor substrate. .

[0002]

2. Description of the Related Art In a conventional resist pattern forming method,
After applying the resist layer on the substrate, g-line (wavelength 436n
m), i-line (wavelength 365 nm) or KrF excimer laser (wavelength 248 nm) is used to perform exposure, and then a method of developing with an alkaline aqueous solution has been used. In such a conventional method, the resolution R and the depth of focus DOF are given by the following expressions, where λ is the exposure wavelength and NA is the numerical aperture of the exposure lens.

[0003]

Therefore, in order to increase the resolution, it is sufficient to shorten the exposure wavelength and increase the NA of the lens. Actually, until now, the miniaturization of patterns has been achieved by shortening the wavelength and increasing the NA. However, the shortening of wavelength and the increase in NA can improve the resolution and D
This leads to a decrease in OF.

At present, in semiconductor devices, as the degree of integration increases year by year, the circuit pattern is further miniaturized, and it is becoming difficult to achieve both resolution and DOF at the same time. Therefore, there is a demand for a pattern forming method that exceeds the limit of conventional pattern formation.

As one of such methods, Japanese Laid-Open Patent Publication No.
As shown in 364021, there has been proposed a method of swelling a resist by forming a resist pattern and then heating before and after the softening point temperature of the resist to make the pattern finer.

[0007]

However, the first problem of the prior art is that the resist shape deteriorates when the resist is swollen by heating. The reason is,
In order to swell the resist, it is necessary to heat the resist to the softening point temperature, but if the softening point temperature is exceeded, the resist may reflow.

A second problem is that when a pattern is miniaturized by heating, the dimension to be reduced changes depending on the density of the pattern, so that the finished dimension may not be the designed value depending on the pattern. Is. The reason is that the pattern is miniaturized by reflow.

An object of the present invention is to provide a forming method in which a pattern is miniaturized without causing resist shape deterioration and not depending on the pattern density.

[0010]

The present invention relates to a method of forming a resist pattern on a substrate, which comprises a step of applying a resist on the substrate, a step of exposing the resist, a step of developing the resist, and a resist. It is characterized by having a step of binding an organic amine. You may heat during the process of couple | bonding a resist and an organic amine. As the organic amine, di-t-butylamine, dicyclohexamine, or the like can be used.

According to the above pattern forming method, by placing the resist pattern in an organic amine atmosphere,
Since the organic amine and the resin of the resist are bound to each other and the organic amine is taken into the resist, the resist pattern swells. As a result, the space portion of the resist pattern can be miniaturized. Here, by heating when placing in an organic amine atmosphere, the binding reaction between the organic amine and the resist resin is accelerated, and the pattern can be made finer. According to this method, it is possible to prevent the resist shape from deteriorating by suppressing the temperature during heating to the softening point temperature of the resist or lower. Further, since the swelling is not performed by using the reflow, the pattern reduction does not depend on the pattern density.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. 1A to 1C are cross-sectional views showing a resist pattern forming process according to the first embodiment of the present invention.

On the semiconductor substrate 1, an i-line positive resist 2 (PFI-26, manufactured by Sumitomo Chemical Co., Ltd.) is used.
After coating to a thickness of μm, the mask 3 shown in FIG. 1A is used to perform exposure using an i-line exposure device. Then 110
After post-exposure bake at 90 ° C. for 90 seconds, development is performed for 60 seconds with a developer of 2.38% tetramethylammonium hydroxide (TMAH) to form a resist pattern (FIG. 1 (b)). The width of the space portion at this time is W1. Then, for example, baking is performed at 120 ° C. for 4 minutes in an atmosphere of di-t-butylamine. As a result, FIG. 1 (c)
As shown in FIG. 5, the width of the space portion of the resist becomes W2, and a pattern reduced by about 0.1 μm can be obtained.

In the conventional method of swelling a resist by heating, the resist shapes after development and after swelling by heating are shown in FIGS. 2 (a) and 2 (b), respectively. Due to the swelling, the space width of the resist has a space width from W1 to W
Although it is reduced to 2 ', the shoulder drop at the top of the resist due to reflow also occurs at the same time. As described above, in comparison with the conventional method, the present invention has an advantage that the space portion can be reduced without causing deterioration of the pattern shape.

Next, a second embodiment of the present invention will be described. After applying a negative resist for KrF excimer laser (XP-89131, manufactured by Shipley Far East Co., Ltd.) to a thickness of 0.8 μm on a semiconductor substrate, KrF is used.
Exposing with an excimer laser. Next, after post-exposure bake at 140 ° C. for 60 seconds, the resist pattern is formed by developing with 0.14N TMAH developing solution for 160 seconds. Then, for example, after immersing in a xylene solvent containing 10 wt% dicyclohexylamine and 3 wt% N-methylpyrrolidone (NMP) at 60 ° C. for 3 minutes, rinsing is performed with xylene. As a result, a pattern in which the space portion of the resist is reduced by about 0.15 μm can be obtained.

Although the first and second embodiments have been described above, the present invention is not limited to these embodiments, and various changes can be made. For example, although heating is performed in the organic amine atmosphere in the first embodiment,
The same effect can be obtained by prolonging the treatment time without heating. Further, in the first and second embodiments, di-t-butylamine and dicyclohexylamine are used as the organic amine, but the same effect can be obtained by using other organic amines. Further, in the above-described embodiment, the positive resist for i-line and the negative resist for KrF excimer laser are used. However, in addition to this, positive or negative g-line, ArF excimer laser, electron beam,
A resist for X-ray can be used.

[0017]

As described above, according to the present invention,
The pattern can be miniaturized without causing the resist shape deterioration and depending on the pattern density.

[0018]

[Brief description of drawings]

1A to 1C are explanatory views of a pattern forming process according to a first embodiment of the present invention.

2 (a) and 2 (b) are diagrams showing resist shapes when the resist is swollen by a conventional method.

[Explanation of symbols]

 1 substrate 2 resist 3 mask

Claims (5)

[Claims] 1. A step of applying a resist on a substrate, a step of exposing the resist, a step of developing the resist,
A method of forming a resist pattern, which comprises the step of combining a resist with an organic amine. 2. A step of applying a resist on a substrate, a step of exposing the resist, a step of developing the resist,
And a step of heating the resist in an organic amine atmosphere. 3. A step of applying a resist on a substrate, a step of exposing the resist, a step of developing the resist,
And a step of immersing the resist in an organic solvent containing an organic amine. 4. The resist pattern forming method according to claim 1, wherein the organic amine is di-t-butylamine. 5. The method for forming a resist pattern according to claim 2, wherein the organic amine is dicyclohexylamine.