JPS5880638A - Stripping solution for positive photoresist - Google Patents

Abstract

PURPOSE:To enable washing in water as operation after stripping by using a morpholine soln. as a stripping soln. for a spoitive photoresist. CONSTITUTION:A morpholine soln. heated to 80-90 deg.C or a mixed soln. of morpholine and N, N'-dimethylformanide heated to 80-90 deg.C is used as a stripping slon. for a positive phototresist formed on a silicon wafer having an oxidized surface. The wafer is immersed in the heated soln. and allowed to stand for 5min. The photoresist is thoroughly dissolved and removed. The wafer is then washed in pure water. The stripping soln. does not erode an Al film as the substrate, and since the soln. is an aqueous soln., operation after removing the photoresist is sufficiently carried out only by washing in water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positive type photoresist (J'fl stripping solution) In photoetching in semiconductor manufacturing, the process of photolithography from above a semiconductor substrate is essential.

In the case of photoresist, positive photoresist is usually a photosensitive polymeric organic material, and when it is cured by heat, it is difficult to peel off with ordinary organic solvents. For reasons such as the inability to use substances that would attack the aluminum substrate when applied to the surface, there are significant restrictions on the substances that can be used as stripping liquids, and until now, no satisfactory material has been found. Not served.

Conventionally, phenolic organic solvents have been used as stripping solutions for positive photoresists, but these have difficulties in waste liquid treatment and are not water-soluble, making post-treatment processes complicated. It had various drawbacks. recently,
In order to alleviate these problems, organic solvents such as ethanol and acetone and basic substances such as potassium hydroxide,
Aqueous ammonia or a mixture of organic amines is used, but in this case, the resist must be decomposed by ultraviolet irradiation before the resist is removed, or if this remover alone is used, the photo There are various drawbacks, such as the fact that the resist cannot be completely removed, and that it is extremely difficult to peel off, especially in the case of positive photoresists that have been post-baked at high temperatures (140° C. or higher).

The present inventors aimed to provide a positive photoresist stripping solution that does not have the above-mentioned drawbacks of conventional positive photoresist stripping solutions and can be washed with water after processing. As a result of various studies, the present invention has succeeded in providing a novel positive photoresist stripping solution that can achieve the intended purpose.

That is, the present inventors have discovered that when morpholine is used as a stripper for positive photoresist, the photoresist can be almost completely removed without damaging the aluminum of the substrate. Moreover, since this material is water-soluble, it also has the advantage that post-treatment operations can be performed by washing with water. Therefore, the present invention provides a positive photoresist stripping solution characterized by using morpholine.

Furthermore, the present inventors have discovered that morpholine and u, N/
/ It has been found that the resist can be more completely removed by using a mixed solution with dimethylformamide. N, N'
-Dimethylformamide is also water-soluble like morpholine, and this mixture is extremely useful as a water-soluble stripper for positive photoresists.

In this case, the mixing ratio of morpholine and N,N'-)methylformamide is 20 to 8° volume of morpholine to N,
N'-dimethylformamide 80 to 20 volumes.

EXAMPLES The present invention will be described below with reference to Examples of the present invention.

Example 1 A film of positive type photoresist AZ 145DJ (trade name of 5hipley) is formed to a thickness of 15,000 mm on a silicon wafer whose surface has been oxidized. Thereafter, prebaking, exposure, development, rinsing and post baking were performed in the usual manner, and the 5102 film was etched using this photoresist film as a mask.

Thereafter, the wafer was immersed in morpholine heated to 80-90°C and left for 5 minutes. The photoresist was completely dissolved and removed. Cleaning after removing the photoresist was performed with pure water. Confirmation of photoresist removal was observed using a differential interference microscope.

Example 2 Wafers prepared in the same manner as in Example 1 were heated to 80 to 90
Morpholine heated to 8°C and N,N'-dimet
Immerse it in a stripping solution consisting of 20% chloroformamide,
Leave it for a minute. Photoresist 1 was completely dissolved and removed. After washing this with pure water, it was confirmed that there was no photoresist residue using a differential interference microscope.

Example 5 An aluminum layer was deposited on a silicon wafer with an oxidized surface, and a positive photoresist AZ-135 was applied thereon.
0J (product name of 5hipley) film at 15000X
Form to a thickness of . After that, pre-baking and
Exposure, development, rinsing and post baking were performed, and the aluminum film was etched using the resulting photoresist and film as a mask.

The wafer was then heated to 80-90°C with morpholine 2.
0 volume of N,N'-dimethylformamide was placed. The photoresist was completely dissolved and removed. This was washed with pure water, and removal of the photoresist was confirmed using a differential interference microscope.

Note that the aluminum of the substrate was, of course, not corroded.

As is clear from the above, in the present invention, by heating morpholine or a mixed solution of morpholine and N,N'-dimethylformamide to 80 to 90°C, it is possible to completely remove morpholine from conventional solvent types. There are cases where high-temperature positive photoresists that could not be completely removed are easily dissolved and removed from the substrate.The stripping solution of the present invention does not attack the aluminum of the substrate and is water-soluble, so the photoresist can be easily removed. It is extremely useful in that the step after removal is just washing with water, and the C-burying step is simple and free of any problems.

Patent applicant: Kanto Kagaku Co., Ltd.

Claims (1)

[Scope of Claims] 1) A water-soluble positive photoresist stripping solution characterized by using morpholine. 2) A water-soluble positive type photoresist stripping solution characterized by using morpholine and N, N'7-i; methylformamide.