Etching phenomena which appeared during the Si membrane process were observed and analyzed. In the case of deep etching to more than 300 in depth, etch defects which existed at the etched surfaces could be classified into 3 categories such as hillocks, adherent reaction products, and white residues. It was known that the hillocks had pyramidal or trapezoidal forms, depending upon the density and size of the reaction products. The density of etch defects, and the etch rate distribution over entire 10cm wafers, were investigated for the cases where the surfaces to be etched were in various positions. It was found that the downward and erect positions were favorable with regard to etch rate uniformity and etch-defect removal, respectively.

B.K.Ju, B.J.Ha, C.J.Kim, M.H.Oh, K.H.Tchah: Japanese Journal of Applied Physics 1, 1992, 31[11], 3489-94