Etching of Silicon - Electrochemistry of Silicon and Its Oxide - page 297

concentrations, below 30%, there is a tendency to form pyramidal islands on the (100)
surface. 206 The density of hillocks varies with temperature, potential, and the presence
of chemical agents in the solution. 114 , 541 The aspect of surface roughness will be dealt
with in more detail in Section 7.7.
Etching Mechanism. The etching of silicon in KOH is a process of dissolution
and hydrogen evolution. Two hydrogen molecules are evolved for each silicon atom
dissolved during the etching. 114 The main etching product is determined to be
which can further be polymerized. 379,1144 Raman spectra also indicate that
is an active etching species, the

intensity decreasing during etching. Water is

also an active species because silicon does not etch in water-free alcohol that contains

as a cation present in the solution is not directly involved in the etching