CD Metrology for Avoiding Shrinkage of ArF Resist Patterns in 100nm ArF Lithography
Tae-Jun You, Cheolkyu Bok, Ki-Soo Shin
Hynix Semiconductor, San 136-1 Amiri, Bubal-eub, Ichon-si, Kyongki-do
We have observed CD(Critical Dimension) shrinkage of acrylate type ArF resist patterns during SEM measurement. CD change was 30% shrinkage for line pattern and 10% expansion for contact hole patterns after 30 times measurement. CD shrinkage was proportion to line pattern size but no relation with LER(Line Edge Roughness). We confirm that CD shrinkage different from resist to resist and SEM measurement condition. CD shrinkage was bigger for acrylate type resist than COMA(Cyclo Olefin Maleic Anhydride) type resist and smaller at lower electron voltage and current conditions. In order to get the improvement of CD shrinkage, we performed electron-beam curing before SEM measurement. Above (see paper for formula) electron-beam dose condition, CD shrinkage improved from 10% to 3%. However, this method caused OPC(Optical Proximity Correction) issue as CD also changed after electron-beam curing. Therefore, we tried to develop a new measurement method instead of applying additional process technique. In this paper, we will describe our CD measurement method, Off-Site measurement technique, for 100nm DRAM lithography. The Off-Site CD measurement repeatability (formula available in paper) was controlled below (see paper).