JPH0281050A - Method and device for surface treating photoresist - Google Patents

Abstract

PURPOSE:To render the section of a photoresist pattern almost perpendicular to a base by surface treating a prescribed resist film in an atmosphere of an alkali vapor. CONSTITUTION:The positive type photoresist film 9 composed essentially of a compound having an o-naphthoquinone diazido group and a cresol/novolak resin is formed on the base 10. Then, the film 9 is surface treated in the atmosphere of the alkali vapor before or after exposure, and developed to form the resist pattern. It is preferred to place an aqueous solution of the alkali (developing solution) into a tightly closed vessel, and to bubble an inert gas through a tube 7 or doing the like, and to introduce it into a chamber 3 in order to prepare the alkali vapor.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a surface treatment method and apparatus for a positive photoresist, which is a mask material for pattern processing.

<Prior Art> A fine photoresist pattern can be obtained by changing the quality of the upper layer of the resist by spin-coating an alkaline aqueous solution (mainly a developer).

The spin coating method is a method of surface treatment in which the substrate 10 on which the photoresist 9 is placed is wetted with an alkaline aqueous solution 5 using a nozzle 17 or the like before exposure, as shown in FIG.

This is published in Japanese Patent Application Laid-Open No. 59-84426, or the Spring 1986 35th Applied Physics Related Conference Preliminary Volume 4 (P, 5
09 28P-H-7, or P, 530 29a-H
-3) etc. are also well known.

Normally, when a positive photoresist film is formed on a substrate to be processed and exposed to light, the intensity of the exposure light reaching the resist becomes weaker as it approaches the surface of the substrate due to light absorption in the resist film, making the resist more exposed to light. The dissolution rate in the developer becomes slow. That is, as shown by the solid line in FIG. 4, the contour lines of the dissolution rate are distributed by the exposure light 15 (photosensitive molecules) that has passed through the transfer mask 14.

Therefore, the shape of the cross section of the resist after the development process is
As shown in the figure, the end portion of the resist pattern has an inclination of angle θ. A resist pattern having such an inclination is an obstacle to microfabrication of a substrate.

Therefore, by using a method in which an alkaline aqueous solution (mainly a developer) is spin-coated and infiltrated into the resist film before exposure, the exposed side of the resist film is more susceptible to the alkaline aqueous solution depending on the degree of infiltration. i'(t?8The solution progresses.

Utilizing this, it is possible to offset the drawback that the intensity of the exposure light becomes weaker toward the surface of the substrate, making it difficult for the resist to be exposed to light, and to make the resist pattern shape vertical.

<Problems to be Solved by the Invention> However, the above-described method of spin coating an alkaline aqueous solution has various practical problems.

In other words, 1) the resist becomes too difficult to dissolve in the developing solution, which tends to leave undeveloped resist residue (resist residue in unexposed areas); 2) the resist is too reactive with the alkaline aqueous solution, and the surface of the substrate to be processed is It is very difficult to control the uniformity within the resist film, the reproducibility between substrates to be processed, and the time control. ■If the alkaline aqueous solution components remaining on the resist film surface are removed by washing with water, the degree of exposure becomes unstable. However, it is difficult to obtain a resist image with high reproducibility.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an excellent surface treatment method and apparatus for surface treatment of a positive photoresist, which is a mask material for pattern processing.

Means for Solving the Problems> The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have arrived at the present invention.

That is, the present invention provides a compound containing an 0-naphthoquinodiazide group as a photosensitive group and a cresol/
A positive photoresist film containing novolac resin as a main component is formed, and a pattern of the resist film is formed by exposure and development. Before or after exposure, the resist film is surface-treated in an alkaline vapor atmosphere. Provided is a photoresist surface treatment method characterized by:

The present invention also provides an alkali vapor generating means, a closed container for alkali vapor treatment of a substrate with a resist film, a means for supplying alkali vapor from the alkali vapor generating means to the container, and an alkali vapor after treatment from the container. A photoresist surface treatment apparatus is provided, characterized in that it has a means for exhausting steam.

Hereinafter, the present invention will be explained in detail.

In the photoresist surface treatment method of the present invention, first, a positive photoresist film containing a compound containing an 0-naphthoquinodiazide group as a photosensitive group and a cresol/novolac resin as a main component is applied onto a substrate to be processed. to form. Next, a transfer mask is placed on the resist film, exposed to light, and developed. In the present invention, the resist film is subjected to surface treatment in an alkali vapor atmosphere before or after this exposure.

The alkali vapor: The surrounding air is preferably generated by bubbling an aqueous alkali solution (developer) with an inert gas or N2, or by gasifying the aqueous alkali solution by pressurizing, heating, or the like.

In addition, the alkaline aqueous solution to be used is not particularly limited, but
In terms of cost, it is preferable to use KOH%NaOH or a developing solution that is inexpensive.

In the present invention, the alkali vapor is sprayed onto the resist film.

In other words, alkaline vapor may be caused to flow toward the surface of the resist film using a gas or the like into a container containing a substrate with a resist film.

After spraying with alkali vapor, it is preferable to expose and develop using a boat-based method.

Surface treatment with alkali vapor is not limited to before exposure;
Effective even after exposure.

If it is performed after exposure, it has the effect of improving the uniformity of the resist film and improving the controllability of etching, etc. in the post-process.

In addition, in the conventional alkali coating method, the resist was dissolved and processing after exposure was impossible.

Next, FIG. 1 shows an example of the configuration of an apparatus for carrying out surface treatment of a photoresist according to the present invention.

This device includes an alkali steam generator (means) 1, a supply pipe (means) 2 for the alkali steam generated by this device,
Alkali vapor treatment chamber (container) 3 and the supply pipe 2
It has an exhaust pipe (means) 4 for discharging the gas supplied into the chamber 3 from the chamber after processing.

As shown in FIG. 1, the alkali steam generator 1 includes:
A sealed container is filled with an alkaline aqueous solution 5 such as KOH, NaOH, or a developer, and an inert gas such as He, Ar, or N2 gas is flowed into the tube 7 as shown by the arrow 6 to cause bubbling or pressurization. Alkaline vapor is generated by methods such as

It may also be generated by heating the alkaline aqueous solution, although the controllability is somewhat inferior.

The alkali vapor is conveyed to the chamber 3 via the alkali vapor supply pipe 2 as shown by arrow 8.

Incidentally, it is preferable to install a switching valve for switching to inert gas in the middle of the alkali vapor supply pipe 2 so as to enable strict time control.

The chamber 3 includes the alkali vapor supply pipe 2 and the discharge pipe 4, and within the chamber 3, a substrate 10 coated with a photoresist 9 can be placed on a substrate mounting table 11.

Alkali vapor is sprayed onto the photoresist 9 deposited on the substrate 10 as shown by arrow 12 in FIG.

Although the present configuration example shows a case where the supply pipe has one supply port so that the alkali vapor is evenly distributed over the photoresist layer 9, a plurality of supply ports may be provided.

The alkali vapor not deposited on the photoresist 9 is then discharged in the direction indicated by the arrow 13 of the discharge pipe 4.

<Example> Hereinafter, the present invention will be specifically explained based on Examples.

(Example) As shown in FIG. 1, by bubbling an alkaline aqueous solution 2 with nitrogen gas and injecting the generated nitrogen gas containing alkali vapor onto a substrate 10 on which a photoresist film 9 is attached. Surface treatment was performed for 120 seconds.

Note that a silicon wafer with a diameter of 6 inches was used as the substrate 10, and as a photoresist. - Using a novolak resist containing naphthoquinonediazide groups as photosensitive groups, the film thickness is 1.6 μm at 9 points on the substrate surface, and the pattern size is 1.0 μm.
A photoresist in-pattern with a width of μm was formed, and the line pattern dimensions and the in-plane distribution of the angle θ at the end were examined using a scanning electron microscope. (See Figure 2).

The results are shown in Table 1.

(Comparative Example 1) As shown in FIG. 2, the surface of the resist was treated for 10 seconds by a normal alkaline aqueous solution spin coating method.

Next, a line pattern was formed in the same manner as in Example 1, and the line pattern dimensions and the in-plane distribution of the end angle θ were examined, and the results are shown in Table 1.

(Comparative Example 2) A line pattern was formed in the same manner as described above without performing the surface treatment with alkali all at once, and the in-plane distribution of line pattern dimensions and end angles was examined.

The results are shown in Table 1.

Table 1 From the above table, the present invention improves the dimensional uniformity of the line pattern compared to the conventional one, and the angle θ of the pattern end is 1.
It has improved by more than 5 degrees and is now almost vertical.

In addition, there was almost no residual development of the resist caused by the alkali surface treatment.

<Effects of the Invention> By performing the surface treatment of the present invention, a fine nearly vertical photoresist pattern can be obtained even with a thick photoresist layer.

Furthermore, the in-plane uniformity of the resist pattern dimensions on the surface of the processed substrate is significantly improved compared to the conventional method.

In addition, the time controllability is much better than that of the conventional method, and the undeveloped photoresist that tends to occur is almost completely eliminated.

[Brief explanation of the drawing]

FIG. 1 is a circular route diagram of the surface treatment apparatus according to the present invention. FIG. 2 is a ring map showing measurement points on the substrate in the example. FIG. 3 is a circular diagram showing a conventional surface treatment method using an alkali. FIG. 4 is a diagram showing the distribution of contour lines of dissolution rate when exposure light passes through a transfer mask using a conventional method. FIG. 5 is a cross-sectional view of a conventional resist pattern. Explanation of symbols 1...Alkali steam generator, 2...Alkali supply pipe, 3...Chamber, 4...Alkali vapor discharge pipe, 5...Alkaline aqueous solution, 6...N2 gas flow Direction, 7... Gas supply pipe, 8... Direction of alkali vapor flowing from the supply pipe to the chamber, 9... Photoresist, 10... Substrate, 11... Substrate mounting table, 12... - Alkali vapor supply method, 13... Alkali vapor discharge method, 14... Transfer mask, 15... Exposure light, 16... Measurement point, 17... Alkaline aqueous solution protruding nozzle FI G, 2 1raFIG, 4

Claims (2)

[Claims] (1) A positive photoresist film mainly composed of a compound containing an o-naphthoquinodiazide group as a photosensitive group and a cresol/novolak resin is formed on the substrate to be processed, and the resist film is exposed and developed. 1. A method for surface treatment of a photoresist, characterized in that, in forming a pattern, the resist film is surface treated in an alkali vapor atmosphere before or after exposure. (2) an alkali vapor generating means, an airtight container for alkali vapor treatment of a substrate with a resist film, a means for supplying alkali vapor from the alkali vapor generating means to the container, and exhausting the alkali vapor after treatment from the container; 1. A photoresist surface treatment apparatus comprising: means for treating a surface of a photoresist;