Reactive ion beam etching of HfO2 film and removal of sidewall redeposition

Comparative studies on ion beam etching (IBE) and reactive ion beam etching (RIBE) of Hf O2 film have been carried out using photoresist as the masking layer. The etching rates of Hf O2 film and photoresist mask in pure Ar and ArCH F3 mixture plasmas were measured as a function of ion energy, plasma composition, and ion beam incident angle. It has been found that the RIBE with ArCH F3 plasma is capable of lowering the threshold energy of ion beam and increasing sputtering yield, compared to the IBE with pure Ar. The redeposition of photoresist sidewall is a major issue, due to the formation of nonvolatile etching products during sputtering of Hf O2 film in both IBE and RIBE. However, the sidewall redeposition can be easily removed in HCl solutions with assistance of ultrasonic wave for RIBE with ArCH F3 plasma. Alternatively, the sidewall redeposition can be eliminated by controlling the slope of photoresist sidewall or combined with ion incident angle. © 2006 American Vacuum Society.