Silicon etching yields in F sub(2), Cl sub(2), Br sub(2), and HBr high density plasmas

The etching yields of silicon in fluorine, chlorine, bromine and hydrogen bromide high density plasmas were measured as a function of ion-bombardment energy, ion bombardment angle and plasma composition. All plasmas showed increase in etching yields with the square root of ion energy. Chlorine and HBr plasmas showed similar etching yields, but ion flux was lower in HBr plasmas causing a lower etching rate. HBr plasmas showed higher etching yields than bromine plasmas due to the ability of H atoms to penetrate into the lattice and form volatile reaction products. The etching yield in HBr plasmas decreased with increase in silicon temperature due to reduced surface coverage by adsorped Br and H atoms.