Homogeneous and amorphous sputtered Sp3-bonded BN films at RT:: a stress, spectroscopic ellipsometry and XPS study

A study of amorphous and homogeneous BN (a-BN) films produced by r.f. magnetron sputtering on c-Si(1 0 0) substrates at room temperature is presented. a-BN films with mixed sp(3)- and sp(2)-bonded BN, were studied in terms of internal stresses, bonding configuration and composition. The optical properties and the composition of BN films were examined by spectroscopic ellipsometry based on specific criteria such as optical gap; while the presence of sp(3)-bonded BN in the films was also identified by high resolution X-ray photoelectron spectroscopy. It was found that the growth mechanism of sputtered BN films is sensitive to bias voltage (V-b). There is an ion energy range (40 V < \V-b\ < 80 V), where sp(3)-bonded BN is predominant, providing films with internal compressive stresses approximately 8 GPa. A threshold stress value of 3.5 GPa, the same as for the formation of the c-BN phase, was measured for the formation of the sp(3) bonding in the amorphous network of a-BN films. (C) 2002 Elsevier Science B.V. All rights reserved.