Examination of develop puddle time and its effects on lithographic performance

摘要

Abstract: As critical dimensions continue to shrink, the importance of robust process windows for these smaller features becomes increasingly evident. There are, seemingly, an unlimited number of variables involved in optimizing a photolithography process to maximize a photoresist and developer system's process window. One of the more influential variables is the develop process, and more specifically, the develop puddle time. The effect of develop puddle time on overall lithographic performance has been investigated. Three runs each were processed varying single spray puddle develop times from 10 seconds to 80 seconds. The responses include dose to clear (Eo), sizing energy (Es), masking linearity, resolution, under, over, and total exposure latitude, focus latitude, iso/dense bias, and resist profile. Also, suggested possible indicators of lithographic performance, such as, sizing ratio (Es/Et) and contrast (gamma) were observed. The effects of develop puddle time on lithographic performance, the `usable' develop puddle time range, and the viability of Es/Et Ratio and gamma as indicators of lithographic performance will be described. Based on the results, optimal puddle times are recommended for increased lithographic performance.!4