High-selectivity inductively coupled plasma etching of HfO2 by using metal hard mask

Traditional photoresist (PR) masks exhibit poor selectivity in the etching of HfO2, resulting in device damage and process control challenges. In this paper, we employ metal hard masks and CHF3/Ar mixed gas to investigate the etching selectivity of HfO2 under various inductively coupled plasma (ICP) etching conditions. The etching sidewall angle was optimized by adjusting process parameters. The results show that Cr mask provides the best etching selectivity, achieving an HfO2/Cr selectivity above 10. By adjusting the bias power and process pressure, the etching sidewall angle was improved from 56.8° to 70.3°, enabling high-precision, defect-free patterning.