JPS63177518A - Formation of pattern - Google Patents

Abstract

PURPOSE:To prevent easily an edge decrease and improve thermal resistance of a resist pattern by bringing a resin film into contact with an alkaline solution after coating photosensitive resin on a semiconductor substrate and further by performing a heat treatment for its film. CONSTITUTION:A photoresist film coated on a semiconductor substrate 1 is immersed, for example, in an alkaline solution (around 2.38 wt.%) containing tetramethylammonium hydroxide for about 60 seconds. After that, the resist film is treated by heat on a hot plate, for example, at a temp. 95 deg.C for 4 minutes. Then exposure and development are carried out through an adequate mask and a resist pattern 2 improved in thermal resistance is formed on the substrate 1 without decreasing edges. As to alkaline solutions, if its concentration is desired one, either of solutions such as NaOH or the 4 class ammonium hydroxide and the like is acceptable. And as regards photoresist, either of compounds of cresolformalin resin series where naphthoquinone diazide class is used as sensitive materials or polyvinyl phenol series are acceptable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a pattern forming method, and particularly to a pattern forming method for forming a resist pattern on a semiconductor substrate using a photosensitive resin.

(Prior Art) Conventionally, when manufacturing semiconductor devices such as LSI, photoresist (photosensitive resin) coated on a semiconductor substrate is used.
Apply a suitable mask to the film, then expose,
By performing development, a desired pattern is formed on the semiconductor substrate.

The technique of forming a photoresist pattern on a semiconductor substrate is one of the important techniques for microfabrication, and the improvement of reliability in microfabrication depends on the photoresist pattern formation technique. Furthermore, photoresists have the ability to form fine patterns (resolution).
In addition to obtaining a good profile shape, it is also required to have sufficient resistance as a mask material because it is exposed to high temperature and high power atmospheres during etching, ion implantation, lift-off processes, etc.

(Problems to be Solved by the Invention) However, the resolution and profile shape, which are important for achieving microfabrication with the characteristics and properties of the resist pattern obtained by the above-mentioned conventional means, are limited by the exposure equipment used, such as the stepper. Since this largely depends on the exposure wavelength and the numerical aperture of the lens, as the pattern size approaches the resolution limit of the exposure apparatus, the upper part of the resist pattern 2 formed on the semiconductor substrate 1 becomes smaller as shown in FIG. , the edge decreases C1i'
) occurs. In particular, if the imaging position (focus) of the exposure device shifts even a little, the edge reduction and film reduction will occur significantly.

Therefore, in order to obtain a good resist pattern, photosensitive compositions containing positive type so-called naphthoquinone diazide as a photosensitizer and alkali-soluble resol-formalin resin as a binder resin are now widely used in the production of semiconductor devices such as LSIs. However, in order to improve the shape and resolution of a good resist profile, the molecules of the binder resin are being lowered, and as a result, the heat resistance of the resist pattern (the temperature at which the profile begins to deform due to heat) has been lowered. There is a problem that the information is damaged.

The present invention has been made in view of the above points, and an object of the present invention is to provide a pattern forming method that can reduce the amount of edge loss of a resist pattern, improve heat resistance, and form an appropriate fine pattern. The purpose is to

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the pattern forming method according to the present invention includes a step of applying a photosensitive resin onto a semiconductor substrate, and a step of bringing the photosensitive resin film into contact with an alkaline aqueous solution. It consists of a step of performing post-heat treatment, and a step of exposing and developing the photosensitive resin.

(Function) In the present invention, after coating a photosensitive resin on a semiconductor substrate, this resin film is brought into contact with an alkaline aqueous solution and further heat-treated, thereby making it possible to use a special photosensitive resin. Therefore, it is possible to prevent edge reduction in resist patterns, particularly fine patterns, and to significantly improve heat resistance.

(Example) An embodiment of the present invention will be described below with reference to FIG.

In this example, after applying a photoresist to a resist film thickness of approximately 1.5 μm on the semiconductor substrate 1, this photoresist film is immersed for 60 seconds in an alkaline aqueous solution (2.38 wt%) containing tetramethylammonium hydroxide. do. Thereafter, the resist film is heat-treated on a hot plate at 95° C. for 4 minutes, and then exposed and developed through a suitable mask to form a resist pattern 2 on the substrate 1.

As the alkaline aqueous solution, any alkaline aqueous solution such as NaOH or quaternary ammonium hydroxide may be used as long as the concentration is adjusted so that the film thickness loss after immersion treatment is maintained at 0.5 μm or less. Well, again.
The photoresist may be any material as long as it is a cresol-formalin resin-based material or a polyvinylphenol-based material that uses naphthoquinone diazide as a photosensitizer.

Therefore, with the above method, it is possible to prevent edge loss in resist patterns, especially fine patterns, with extremely simple means without using special photosensitive resins or expensive exposure equipment, and to improve heat resistance. It is possible to significantly improve this.

The 0.6 μm wide line and space resist patterns obtained in this example were examined using a scanning electron microscope (magnification ×2.
As a result of observation in FIG. 1, it can be seen that, compared to the conventional pattern 2 shown in FIG. 2, the edge reduction of the upper part of the resist pattern 2 is prevented as shown in FIG.

Further, as a result of conducting a heat resistance test of the above resist pattern by heating it with a hot plate, it was found that the heat resistance was improved by about 10° C. compared to a resist pattern made by a conventional method.

〔Effect of the invention〕

As described above, the pattern forming method according to the present invention includes:
After coating a photosensitive resin on a semiconductor substrate, this resin film is brought into contact with an alkaline aqueous solution and further heat-treated to easily form a resist pattern, especially a fine pattern, without using any special photosensitive resin. This makes it possible to prevent edge loss and significantly improve heat resistance. In addition, since the treatment process is simple and no special equipment is required, it is economical and highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a profile shape obtained by the present invention, and FIG. 2 is a longitudinal sectional view showing a profile shape obtained by a conventional method. l...Semiconductor substrate, 2...Resist pattern. Applicant's agent Yu Sato Figure 1 Figure 2

Claims (1)

[Claims] It is characterized by comprising the steps of applying a photosensitive resin onto a semiconductor substrate, bringing the photosensitive resin film into contact with an alkaline aqueous solution and then subjecting it to heat treatment, and exposing and developing the photosensitive resin. pattern formation method.