Impact of development chemistry on extreme ultraviolet resist performance

Abstract

Tetrabutyl ammonium hydroxide (TBAH) has recently been identified as a promising material for aqueous base development of extreme ultraviolet (EUV) photoresists. In this article, the merits and applicability of this new material are being further investigated. In general, TBAH has no impact on line width roughness or sensitivity performance when compared to conventional tetramethyl ammonium hydroxide. It does, however, improve the pattern collapse performance of several resists. Since pattern collapse is an important failure mechanism for EUV, TBAH also improves ultimate resolution of these materials and allows overexposure to target smaller critical dimensions. In contrast, several other resist platforms show no impact of TBAH on their pattern collapse behavior. A mechanism is proposed to explain this observation based on modification of the chemical surface properties during development. This mechanism is supported by independent contact angle measurements.