Si surface texture by pyramid structure ZnO glass mask blank

Abstract

In this work, a textured surface structure of Si substrate has been prepared using pyramid structure ZnO glass as mask, and the structure of textured surface and reflection characteristics of Si substrate have been analyzed by scanning electron microscope (SEM) and reflectivity spectra. The results show that U-shaped structure is formed on the surface of photoresist after the incidence of ultraviolet light, and it is caused by the different decrement of light intensity in the ZnO glass Mask Blank. The U-shaped structure which is same with the photoresist appears at the surface of Si substrate after reactive ion etching (RIE) process, and the size of U-shaped structure is in the range of 0.5-1.5 μm. Needle-like morphology caused by the RIE process appears on the U-shaped structure. The reflectivity of the U-shaped Si surface is decreased by the needle-like morphology, and it is protected by the U-shaped structure. The textured structure etched at different pressure is further investigated, and the results suggest that the reflectance of the sample reduces firstly and then increases with the decrease of pressure, and a minimal average reflectance is obtained at 0.8 Pa. The ion damage of Si surface is reduced in the second texturing process, which is useful for film deposition. The results suggest that low reflectance and textured surface of Si substrate can be obtained by ZnO glass mask blank with natural pyramid structure, which is meaningful for light trapping in solar cells.