Study of diamond films grown at low temperatures and pressures by ECR-assisted CVD

We have studied a set of diamond films grown at low temperatures and pressu res by electron cyclotron resonance (ECR)assisted chemical vapor deposition (CVD). These films were grown on Si (100) substrates at temperatures rangi ng between 550 and 710 degrees C and pressures ranging between 1 and 2 Torr . Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffrac tion( XRD) were employed to investigate the crystalline quality, diamond yi eld, and stresses developed in these films. Our Raman lineshape analysis in dicates that most of the diamond films exhibit a net compressive stress. An estimate of the net stresses developed in these films was made by adding t he thermal interfacial stress component to the calculated stress developed at the grain boundaries from the X-ray analysis. It was found that the resi dual stress is compressive in nature, but less compressive than that calcul ated from the Raman shift. The net stress exhibits a strong correlation wit h the relative amount of non-sp(3) phase, thus implying that the non-sp(3) phase is causing the measured excess compressive stress. However, the cryst alline quality of the diamond phase improves as the overall non-sp(3) compo nent increases, thus indicating a process analogous to phase segregation wi thin the films. These results indicate that the source of the excess compre ssive stress is non-sp(3)-bonded carbon accumulated at the grain boundaries . (C) 1999 Elsevier Science S.A. All rights reserved.