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UV Hardening of Resist Images

IP.com Disclosure Number: IPCOM000042667D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Clecak, NJ: AUTHOR [+3]

Abstract

The fabrication of microelectric circuits demands resist materials to be highly resistant to high temperatures encountered in reactive ion etching (RIE) and ion implantation processes. However, many resists are prone to image flow at elevated temperatures. For example, typical AZ resist images as developed show a significant thermal flow even at about 100ŒC. The resist consisting of poly(p-t-butoxycarbonyloxystyrene) (PBOCST) and an onium salt cationic photoinitiator is sensitive to deep UV (ultraviolet), E-beam and X-ray radiations, and can be made sensitive to mid and near UV radiations.

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UV Hardening of Resist Images

The fabrication of microelectric circuits demands resist materials to be highly resistant to high temperatures encountered in reactive ion etching (RIE) and ion implantation processes. However, many resists are prone to image flow at elevated temperatures. For example, typical AZ resist images as developed show a significant thermal flow even at about 100OEC. The resist consisting of poly(p-t-butoxycarbonyloxystyrene) (PBOCST) and an onium salt cationic photoinitiator is sensitive to deep UV (ultraviolet), E-beam and X-ray radiations, and can be made sensitive to mid and near UV radiations. The acid generated via radiolysis of the onium salt cleaves the tBOC group to form poly(p- hydroxystyrene) in the exposed regions, which results in a great change in the polarity of the repeating units, thus allowing either positive or negative patterning upon choice of a developer. The resist film remaining after the negative patterning by development in a nonpolar solvent (dichloromethane-hexane) consists of poly(p-hydroxystyrene), which, as indicated by DSC analysis, has a glass transition temperature (Tg) of about 175OEC. In consequence, the negative image does not flow at all when heated at 170OEC for 30 minutes, as evidenced by retention of finely defined submicron features. The negative image does flow when baked at 210OEC for 30 minutes. However, blanket UV exposure prior to heating dramatically improves the thermal stability of the negati...