Real-time strain monitoring in thin film growth: cubic boron nitride on Si (100)

We demonstrate the application of real-time film-stress monitoring and control using a multi-beam optical sensor. In situ measurements on wide-bandgap boron nitride films grown by ECR-assisted sputtering reveal a critical stress beyond which defects are injected into the silicon substrate. This is marked by a rapid onset of wafer curvature. The method should be particularly useful for monitoring stress build-up in other wide-bandgap nitride films where no appropriate lattice-matched substrates are presently available.