Ion-assisted etching of boron nitride in radio frequency capacitive discharges

Thin films composed of a mixture of hexagonal and cubic boron nitride (h-BN/c-BN) were treated by Ar, Ar/H-2 and Ar/Cl-2 plasma in a radio frequency (RF) capacitively coupled discharge. The c-BN concentration in the film, as measured by Fourier transformed infrared spectroscopy (FTIR), was increased by post-treatment under the described conditions. The Ar plasma used to identify the ion bombardment effect resulted in a slight increase in c-BN concentration. Ar/H-2 and Ar/Cl-2 treatments were more efficient in increasing the c-BN concentration and illustrated chemical effects and ion-assisted preferential etching of the h-BN by atomic hydrogen and Cl ions. These preliminary results are discussed in view of a new deposition route for stress-reduced c-BN. (C) 1998 Elsevier Science S.A.