Metal oxide resists (MORs) have been becoming one of the most promising candidates that facilitates the extension of EUV single exposure by improving both lithographic resolution and etch selectivity. However, to succeed high volume manufacturing, the MORs process should be robust and persistent regardless of lithographic process fluctuation that might occur. In this work, the systematic examinations on the MORs process have been explored in order to understand the MORs patterning mechanism. We found that the ADI CD (After Development Inspection Critical Dimension) could be varied with trivial fluctuation of EUV radiation, humidity, and incomplete condensation reaction. In particular, the humidity around a coated resist was the important element that affected the condensation reaction and determined the insolubility of MORs against developer solution, which consequently defines the ADI CD. Thus, the methods that enable not only the moisture control but the sufficient condensation reaction were carefully examined. Moreover, it is investigated whether MORs can enhance further the etch selectivity while reducing the intrinsic resist defect. Several strategies have been implemented, which allow the CD variation to be reduced and the process window to be enlarged compared to the early stage MORs processes.
|