New slit scan developer system for advanced 45- nm mask making

To improve Critical Dimension (CD) uniformity is an important task in 65nm generation photomask and the beyond. It is known the develop process generates the CD variation. This study is focused on develop process. We initiated new type developer nozzle in this study to improve the CD uniformity. We devoted to improve the CD uniformity during develop process by optimizing the develop parameter through a Design of Experiment (DOE). In the first step, we chose 11 parameters (Scan speed, Dispense flow rate, Develop time, Gap between photomask surface and slit nozzle edge) for L12 test to make sure which can control process. After the L12 test we selected 3 parameters (During develop dry/ not, During develop rinse/not and scan times) for L4 test to optimized this experiment. Dependence on the L12 and L4 result, we get the best recipe. With the best recipe from L12 and L4, we verified CD uniformity in our production pattern..The CD target was 0.36um and CD uniformity was 6.8nm (range) We also studied about the relation of CD uniformity and process bias with the parameter.