Selective plasma etching of ZrOx to Si using inductively coupled BCl3/C4F8 plasmas

In this study, the etch characteristics of ZrOx and the etch selectivity to Si were investigated using BCl3/C4F8 plasmas. The etching mechanism was also investigated. Increasing the C4F8 percentage to 4% formed a C-F polymer layer on the silicon surface due to the increased flux ratio of CFx/F to the substrate, while no such C-F polymer was formed on the ZrOx surface due to the removal of carbon from CFx by the oxygen in ZrOx. By using 3-4% C4F8 in the BCl3/C4F8 mixture, infinite etch selectivity of ZrOx to silicon and photoresist could be obtained while maintaining the ZrOx etch rate above 400 A/min