Formation mechanism of Si(1 0 0) surface morphology in alkaline fluoride solutions was investigated both theoretically and experimentally. By analysis of Raman spectra of silicon wafer surfaces and three kinds of etching solutions (NaOH, NaOH/NH4F, and NaOH/NH4F/Na2CO3) with and without addition of Na2SiO3 center dot 9H(2)O, no Si- F bond is formed, F- and CO32- ions accelerate the condensation of Si- OH groups. Based on experimental results, it is proposed that bare silicon and silicon oxide coexist at the wafer surface during etching process and silicon oxide of different structure, size, and site at the surface manufacture different surface morphology in alkaline fluoride solution. (C) 2011 Elsevier B. V. All rights reserved.