Effect of Surface Roughness on the Adhesion of PECVD coated Silicon-Carbide Thin-films on (110) monocrystalline-Silicon Wafer

Abstract:
Investigations to improve the adhesion between the PECVD coated silicon carbide thin films and monocrystalline (110) silicon wafer substrate is reported. The surface treatment of silicon wafer is realized by roughening the wafer surface by wet etching in 1.8M potassium hydroxide solution at 50 °C with ultrasonic agitation. The average surface roughness of the silicon wafer was increased from 2.9 nm for polished wafer to a range between 32 nm to 250 nm by wet etching for a duration of 10 minutes to 55 minutes, respectively. The adhesion between the PECVD coated silicon carbide thin films (ca. 300 nm thickness) and the silicon wafers with varying surface roughness was characterized by means of scanning scratch test. The critical load initially increased from 153 mN to 169 mN on increasing the average surface roughness from 2.9 nm to 33 nm, respectively. A further increase in average surface roughness adversely influenced the adhesion indicated by a gradual decrement in the critical load to 124 mN for the maximum investigated average surface roughness of 250 nm.