Abstract
The etching properties of HfAlO and silicon wafer with pattern were investigated using inductively coupled high density plasma etcher. The effects of the experimental parameters, including ICP power, bias power, pressure and etch time, on the etch rate and selectivity were studied. The gas species and ratio were fixed at BCl3/Ar and 40/2 sccm. In order to study the etch mechanism and surface roughness, we observed the etched sample by electron spectroscopy for chemical analysis (XPS) and atomic force microscopy (AFM). It was found that the best operation setpoint was at icp power 500 W, pressure 10 mTorr, bias power 10 W~15 W. The over etch process must be operrated under the bias power 10 W. Surface roughness was increased with etch rate increased. From XPS analysis, we oberseved that the B-O bonds on etched HfAlO suface and B-Si bonds on etched Si surface. Because the reducing chemistry of boron removes oxygen to increase HfAlO etch rate, and passivation chemistry of boron bonds silicon to decrease Si etch rate. The resulting selectivity of HfAlO/Si was improved to above 10 in BCl3 plasma, much higher than in Cl2 plasma.