Dissolution Characteristics of Chemically Amplified DUV Resists.

Abstract

Dissolution kinetics of a chemically amplified deep ultraviolet (DUV) positive resist, which consists of tert-butoxycarbonyl (t-BOC) protected phenolic resin, benzenesulfonic acid derivative as a photoacid generator (PAG) and an additional dissolution inhibitor, has been investigated by focusing on the polymer structures (t-BOC blocking level, molecular weight and molecular weight dispersion) and photo-acid structures. Based on the analysis of the dissolution rate curve and Arrhenius plots, it was concluded that only one mechanism, namely, the penetration of tetramethylammonium hydroxide (TMAH) developer into hydrophobic t-BOC resin, rules the dissolution kinetics. It was also found that a steep slope of the dissolution rate curve is very effective for improving resolution capability. Moreover, ideal dissolution characteristics which can realize superior resolution capability, were obtained by analyzing both experimental dissolution rate and resist profile simulation.

Chemical and physical aspects of the post-exposure baking process used for positive-tone chemically amplified resists

“…Acid concentrations are not treated as constant, but undergo continuous reduction through loss processes. Simpler treatments involve the analysis of ionic conductivities [25][26][27] or material loss after development as a function of baking conditions [20,24]. The diffusion coefficients reported in all of these studies are difficult to compare with one another directly because of the differences in polymer, photoacid generator (PAG) type and concentration, post-application bake (PAB) conditions, and PEB temperatures used; they range from 10 Ϫ15 to 10 Ϫ11 cm 2 /s.…”

“…As noted above, because diffusion is accompanied by reaction, the extraction of diffusion kinetics independent of deprotection kinetics is not simple. Numerous investigations of acid diffusion in positive-tone chemically amplified resist systems have been reported using the following to elucidate the coupled reaction-diffusion process: multilayer structures of acidified polymer or a layer of pure acid on pure polymer [20 -22]; linewidth measurements [23,24]; ionic conductivities [23,[25][26][27]; and spectroscopic probes of polymer chemistry changes during or after post-exposure bake [22, 23, 28 -30]. Diffusion coefficients are typically obtained from the experimental measurements in one of three ways.…”

Monte Carlo study of surface and line-width roughness of resist film surfaces during dissolution

“…Simulations [5] have also predicted the same, and this has been justified in terms of the acid diffusion, which softens the difference in exposure between neighboring regions of the resist line to the intermediate region between exposed and un-exposed film. It has been reported that the use of low molecular weight and low dispersivity polymers as resist films decreases roughness and acid diffusion range [39]. Also, the use of low dispersivity polymer films results in smoother side surface and the acid diffusion range can be extended into greater values with acceptable distortions in the final image [33].…”

Insertion effects of various acid sensitive groups into acetal-type polymer on the profile of 248-nm chemically amplified resist

“…Many research groups tried to investigate the dissolution characteristics of chemically amplified DUV resists [14][15]. In our previous report, poly [4-hydroxystyreneco-4-(3-cyano-1,5-di-tert-butyl carbonyl pentyl styrene)] (PHSCBPS) was synthesized and blended with poly(4-hydroxystyrene-co-4-(1-ethylethoxystyrene)) (EEPHS) to understand how the dissolution rate of blended resin can affect the pattern profile of resist [9].…”