Optimization of resist parameters to improve the profile and process window of the contact pattern in advanced node

摘要

Typically, the printing of contact patterns uses a dark-field (DF) mask in combination with a positive tone resist and positive tone development (PTD) process. PTD, which has a mature process and simulation model, had been widely applied in high-volume manufacturing. For the low aerial image quality of a DF mask in advanced node, PTD is substituted by negative tone development (NTD), which uses a positive tone resist and bright-field mask. Due to the high cost and immature simulation model of NTD process, it is worthwhile to extend PTD to some critical patterns. With the purpose of improving the resist profile and process window (PW) of the contact pattern with a PTD process in advanced node, an optimization method combined with the idea of a genetic algorithm is put forward. For performance of the optimized resist under the conditions of best focus and best dose, an evaluation based on the through pitch square contact patterns with the critical dimension (CD) fixed at 50 nm has been provided. The generalization performance of the optimized resist is also analyzed by a systematic method, which contains the resist profile and PW simulation on the base of through CD and through pitch contact patterns. The above simulation results verify the effectiveness and validity Of the proposed Optimization method.