Etching Selectivity And Surface Profile Of Attenuated Phase Shifting Mask Using Cf4/O-2/He Inductively Coupled Plasma (Icp)

Selectivity and etched profile of MoSiON in high-density CF4 /O-2 / He inductively coupled plasma (ICP) have been studied. The etched profiles of MoSiON along with the quartz surface morphologies were investigated as a function of etching parameters by scanning electron microscopy (SEM). We varied pressure from 5 mtorr to 20 mtorr and CF4 flow rate from 15 sccm to 40 sccm. Smooth quartz surface and vertical MoSiON slope was observed under 10 sccm CF4, / 15 SCCM O-2 / -240 V DC bias / 5 mtorr. And the other conditions showed a rough quartz surface and bad MoSiON slope. With these results, we found out that the most dominant factor for the MoSiON profile and quartz morphology was the ratio of CF4 / O-2 flow rate rather than the pressure. So, we varied the ratio from 0.3 to 3 and investigated changes in the quartz morphology and the MoSiON slope. When the ratio was too low, there were MoSiON remains on the quartz surface and if the ratio was too high, the quartz surface was attacked seriously. Only at the appropriate ratio of CF4 / O-2 flow rate, smooth quartz surface could be seen. But at the ratio range of CF4 / O-2 flow rate between 0.3 and 3, no significant change appeared in the MoSiON profile.