Residual stress near by the interface of thin CVD diamond film and silicon substrate

The state of residual stress is investigated for the case of diamond films prepared by microwave plasma chemical vapor deposition. Huge compressive residual stress is found to concentrate in the very thin region just nearby the interface. In addition, the substrate surface is also found to be in compression prior to being covered with the continuous film. The discussion here is focused on the factors, i.e., crystal orientation of the substrate and CH₄ content in the source gas mixture, which may influence the residual stress distribution. As a result, the state of residual stress in the growing surface side of the films changes with these factors, but the nature of compressive residual stress concentration on the interface side remains almost the same. This fact implies that the compressive stress on the interface is expected to be fundamentally related to the nucleation process of diamond on the substrate surface.