Patterning Material Challenges for Improving EUV Stochastics

Abstract

As the industry looks to extend single-expose extreme ultraviolet (EUV) lithography, stochastic effects become a significant concern to enable yield. Multiple previouslypublished reports have shown a strong tradeoff between resist sensitivity and observed stochastic defectivity. However, the limits of this trade-off between improving stochasticsrelated defects with a higher dose resist remains to be understood. How strongly does the resist formulation itself contribute to stochastics, or is it a purely dose-driven effect? Due to the thickness decrease in the patterning stack, the interfacial effects of the resist and hardmask films play a dominant factor in the material stochastics. This offers an opportunity to think differently about underlayer design for sub-32nm pitch patterning. The choice of hardmask can be used to modulate post-litho defectivity to mitigate the stochastics effects and enable more efficient pattern transfer. This paper will address multiple approaches to improving the materials stochastics through resist component optimization and hardmask film development. The defectivity at post-exposure and post-etch are correlated to electrical yield to validate the evaluation. The relative merits of patterning a chemically amplified organic resist directly on an inorganic hardmask or having different types of organic adhesion promoters as an intermediate layer will be also be presented.

Effects of underlayer absorption coefficient on bridging risk in chemically amplified resist process for extreme ultraviolet lithography

“…Interfacial effects have recently attracted much attention owing to the reduction in resist film thickness accompanied by the miniaturization of feature size. [17][18][19][20][21][22][23][24][25] Among them, the low-energy electron dynamics at the interfaces is an important factor. [26][27][28] When there is little difference between the bulk potentials of the resist layer and underlayer, the secondary electrons generated in both layers can cross their interface.…”

极紫外光刻的随机性问题及其研究进展

“…7 Concept and lithographic results of novel functionalized materials [74] 图 8 BQ 变化的缺陷分析 ［75］ 。 (a)电子束光刻后总缺陷密度； (b)纳米桥接缺陷密度； (c)断线缺陷密度 Fig. 8 Defect analysis for BQ variation [75] 10 Process windows for line/space between EUV PTD and EUV NTD [92] 图 9 PTD 和 NTI 光刻工艺流程 ［89-90］ Fig. 9 Process flow of PTD (positivetone development) and NTI (negativetone imaging) lithography [89][90] 0701006 -10 11 Distribution of light intensity on high reflective substrate and a baking step smoothens this concentration pattern by diffusion (from the left to the right shows the chronological sequence of a numerical modelling) [94] 图 12 20 nm 半间距(HP)密集孔图形 LCDU (3σ)随团簇直径变化的模拟结果(成像条件相同) ［95］ Fig.…”