The photoresist developing ability study at different contact angle and mask transmission rate

The PFOA surfactant (chemical structure: (polymer backbone)-C8F17) using in photoresist is forbade own to every country need protect environment, so the PFOA surfactant is replaced by non PFOA type (chemical structure: (polymer)-(CF2) n2 -CF3, n2<4*). Along with the variation, some photoresist contact angle change from 78 degree to 72 degree. The relation between PR contact angle and developing ability is studied in our paper. At the higher contact angle of PFOA photoresist version, weak developing process is not suitable. The results using weak developing recipe show that the lower transmission rate of mask, the worse abnormal CD at wafer edge (abnormal CD: 412nm, normal CD: 344 nm), and the layer with high transmission rate does not have same issue. On the opposite, stronger developing recipe causes high transmission rate layer wafer edge pattern peeling at the lower contact angle of non PFOA photoresist version. In addition, the develop process settings suitable for different contact angle are also studied, which include developing pre wet time optimize.