Failure mechanism of leakage induced by pattern-dependent photo resist distortion

摘要

The difference of pattern in photomask can affect photo resist (PR) profile. For example, pattern density difference or special pattern size will result in unexpected PR profile. In worse case, severe distortion will happen on PR profile, and then etch rate or implant profile can be impacted. Due to the mentioned pattern-dependent PR distortion, some special topological structures in chip layout design may result in serious leakage in devices. In these cases, the solution is usually a mixture of design change and process optimization. In this paper, we study the failure mechanism induced by pattern density dependent microloading effect and special pattern size dependent PR peeling effect. Both the effects are discussed at the range of lithography and implant process. The commonality is that PR profile is impacted dramatically due to the special PR pattern, which results in doping agent injecting in wrong area during implant process and then leakage occurs in devices. For each failure mechanism, solution is presented from point view of design change and process optimization.