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Photoresist Reflow Reversal

IP.com Disclosure Number: IPCOM000041850D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Badami, DA: AUTHOR [+4]

Abstract

A method for reversing the reflowed image of a positive photoresist using plasma hardening and post baking. Due to the small image sizes and the requirement of photoresist profile stability through a number of processing steps, thin photoresist films with exceptional adhesion characteristics are required. Furthermore, the use of a patterned photoresist film as an ion implantation mask requires the film to have a very low pinhole density and relatively high sidewall angles (i.e., above 65Œ). A process that is often used to reduce the number of pinholes and to improve the adhesion of a positive photoresist is to bake the pattern images at a temperature which is beyond the photoresist resin's glass transition temperature (Tg). For example, the photoresist image shown in Fig.

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Photoresist Reflow Reversal

A method for reversing the reflowed image of a positive photoresist using plasma hardening and post baking. Due to the small image sizes and the requirement of photoresist profile stability through a number of processing steps, thin photoresist films with exceptional adhesion characteristics are required. Furthermore, the use of a patterned photoresist film as an ion implantation mask requires the film to have a very low pinhole density and relatively high sidewall angles (i.e., above 65OE). A process that is often used to reduce the number of pinholes and to improve the adhesion of a positive photoresist is to bake the pattern images at a temperature which is beyond the photoresist resin's glass transition temperature (Tg). For example, the photoresist image shown in Fig. 1a can be baked for about 60 minutes at about 120OEC for a reduction of pinholes and an improvement in its adhesion characteristics. This, however, causes the photoresist to change its shape and look like the image shown in Fig. 1b. The image of Fig. 1b has the disadvantage of having lower sidewall angles than it had prior to the baking step. The method described herein provides for the reversal of a reflowed photoresist image with the use of plasma hardening and subsequent baking operations at a temperature much higher than Tg. Sidewall profiles of up to 80% of the original profile are obtained while pinhole density and photoresist adhesion are optimized. For example, by plasma hardening the image of a structure, as shown...