Deep UV photoresists based on poly(dl‐tert‐butyl fumarate)

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Abstract
Poly(di‐tert‐butyl fumarate) was prepared and evaluated as a potential candidate as a deep UV photoresist. Although this polymer displayed excellent sensitivity, the polymer was found to exhibit poor dry etch resistance. Copolymers of di‐tert‐butyl fumarate with either allyltrimethylsilane or styrene, and an onium salt as a photoacid generator were synthesized and subsequently evaluated using a 248‐nm KrF excimer laser step‐and‐repeat system (stepper). At 248 nm, the absorbance of ∼ 1 μm thick resist films was only 0.156‐0.211. The sensitivities of these resists were 1‐4 mJ/cm2. The dry etch resistance of these photoresists was comparable to that of conventional positive photoresists based on novolac resins. © 1995 John Wiley & Sons, Inc.