JPS6226813A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To obtain a good configurational accuracy for the title resist pattern and high resistivity for etching by a method wherein the prescribed pattern is exposed on a photosensitive resist film, and when a resist pattern is going to be formed by hardening after developing, rinsing and drying work is performed, temperature is raised in a step-like manner. CONSTITUTION:A photosensitive photoresist film is coated on the surface of the silicon wafer to be used for manufacture of an IC, and then exposing, developing, washing and drying processes are performed thereon. The silicon wafer 1, wherein a non-hardened resist pattern is formed, is moved to split type hot plates 301-305, and they are moved to the hot plates in the direction as shown by the arrow in the diagram. If the set temperature is raised as going to the downstream of a semiconductor wafer, the semiconductor wafer 1 is moved to the heated region of relatively high temperature from the heated region of relatively low temperature, and the non-hardened pattern on the surface is heated up to a high temperature gradually and hardened. As a result, the final heating temperature can be raised without deterioration of the pattern form, and the formed resist pattern has sufficient resistivity against a reactive ion etching.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for forming a resist pattern used as a mask for selective etching or a mask for ion implantation of impurities in the manufacture of semiconductor devices such as ICs.
In particular, it relates to improvements in the curing method.

[Technical background of the invention]

When manufacturing a semiconductor device, a resist pattern used as a mask in photoetching or the like is formed in the following manner. That is, after a predetermined pattern is exposed to light on a photosensitive resist film applied to the surface of a semiconductor wafer, this is developed, and the remaining pattern obtained by rinsing is heat-cured. Among these steps, the steps following development are conventionally performed as shown in FIG.

In FIG. 2, 10 is a wafer send cassette. The cassette 10 accommodates a semiconductor sea urchin heart that has been exposed. These semiconductor wafers are fed into the developing device 20 one by one. And spinner 2
1 and rotate it, and spray a developer from the liquid supply pipe 22 to perform development. Subsequently, the rinsing liquid is sprayed from the liquid supply pipe 22 for cleaning, and after drying by supplying dry air, the semiconductor wafer 1 is transferred onto the hot plate 30 and moved on the hot plate at a predetermined speed. be done. Since the entire hot plate 30 is heated to a constant temperature of 120° C. to 140° C., the resist film remaining on the wafer surface is heated to the predetermined temperature for the time period during which the semiconductor wafer 1 is transferred on the hot plate. Ru. The resist pattern of the semiconductor wafer that has reached the end of the hot plate 30 has been completely cured, and is accommodated in the wafer receive cassette 40 as it is.

By the way, a resist pattern used as a mask for selective etching and the like is required to have two characteristics: pattern shape accuracy and degree of hardening (resistance to etching). Among these, in order to improve pattern accuracy, it is necessary to cure at a relatively low temperature, and in order to improve the degree of curing, it is necessary to cure at a relatively high temperature.

[Problems with background technology]

As described above, in the conventional resist forming method, the resist pattern remaining after development is heated at a constant temperature when curing it, resulting in the following problems.

First, when the temperature of the hot plate 30 is raised to harden the resist, the crosslinking reaction progresses and sufficient hardness is obtained, but the shape of the resist pattern collapses. That is, before heating, the pattern 2 had a normal rectangular cross-sectional shape as shown in FIG. 3(A), but after heating and curing, the pattern 2 had a semicircular cross-sectional shape 2' as shown in FIG. 3(8). , and the width expands. As a result, if selective etching is performed using this as a mask, a problem arises in that the etching accuracy decreases.

On the other hand, if the hot plate 30 is heated at a relatively low temperature for curing, a resist pattern 3 having a normal cross-sectional shape as shown in FIG. 4(A) is obtained at the end of curing.

However, since this resist pattern 3 is insufficiently cured, it has low resistance to etching, especially reactive ion etching. For this reason, the resist pattern 3 gradually wears out while performing reactive ion etching, and at the end of the etching, the mask width becomes smaller as shown in FIG. 4(B), and the etching accuracy deteriorates. Therefore, a problem arises in that the dimension of the pattern shape is 11 J m.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for forming a resist pattern that has both good shape accuracy and high resistance to etching.

(Summary of the Invention) The method for forming a resist pattern according to the present invention involves exposing a photosensitive resist coated on the surface of a semiconductor wafer to light in a predetermined pattern, developing it, rinsing it, and drying it.
The present invention is characterized in that when the remaining resist film is cured to form a resist pattern, the temperature is raised stepwise to carry out the curing step.

If the temperature is heated stepwise to cure the pattern in this way, a certain degree of crosslinking reaction will proceed while the pattern is heated at a relatively low temperature, the pattern shape will be fixed, and the heat resistance will also improve. Therefore, by subsequently heating at a high temperature, the crosslinking reaction can be completed without softening, and a resist pattern with high etching resistance can be formed while maintaining shape accuracy.

The resist curing step in the present invention may be carried out using any heating means, but it is most preferably carried out using a hot plate.

[Embodiments of the invention]

An example in which heating with a hot plate is used as the curing means will be described below.

First, a photosensitive photoresist film is applied to the surface of a silicon wafer for IC manufacturing, and exposed, developed, washed, and dried in the same manner as before.

The silicon wafer 1 on which the uncured resist pattern has been formed in this way is transferred onto the split-type hot plates 301 to 30 shown in FIG. 1, and moved on the hot plate in the direction of the arrow in the figure.

By the way, the above-mentioned split type hot plates 301 to 305
The temperature is controlled independently, and the set temperature is higher downstream of the semiconductor wafer as shown below. Note that the specific temperature setting varies depending on the type of photosensitive resist used.

Hot plate 30t: Low-temperature hot plate 302: Low-medium temperature hot plate 303: Medium-temperature hot plate 304: Medium-high temperature hot plate 30〈・:High temperature Therefore, the semiconductor wafer 1 moves from a relatively low-temperature heating area to a relatively high-temperature heating area. However, the uncured pattern on the surface is gradually heated to a high temperature and cured.

When a resist pattern for photoetching was formed using the method of the above example, the final heating temperature (temperature set at 30 feet on a hot plate) was lower than that of a conventional hot plate at a low temperature. 5-10
It was possible to raise the temperature.

The formed resist pattern also had sufficient resistance to reactive ion etching, making it possible to form a pattern with high dimensional accuracy.

Although a split hot plate was used as the heating means in the above embodiment, the present invention is not limited thereto, and may be carried out by gradually increasing the heating temperature in an oven.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to form a resist pattern that has both a good degree of shape radius and high resistance to etching, and improves the patterning accuracy of photolithography to manufacture semiconductor devices. Remarkable effects such as improved yield can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the curing process of a resist pattern in an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a conventional method of forming a resist pattern, and FIG.
8> and FIGS. 4(A) and 4(B) are explanatory diagrams showing the problem. DESCRIPTION OF SYMBOLS 1... Semiconductor wafer, 2... Uncured resist pattern, 2'... Resist pattern deformed by high temperature curing, 3... Resist pattern cured at low temperature, 3'
...Resist pattern consumed by reactive ion etching, 10...Wafer send cassette, 20...
Developing device, 21... spinner, 22... liquid supply pipe,
30...Hot plate, 301-30...Divided hot plate, 40...Wafer receive cassette.

Claims (1)

[Claims] After exposing a photosensitive resist film coated on the surface of a semiconductor wafer to a predetermined pattern, developing it, rinsing it, and drying it, the temperature is gradually increased to harden the remaining resist film and form a resist pattern. A method for forming a resist pattern, characterized in that the curing step is performed after the curing process is performed.