Stress study of HFCVD boron-doped diamond films by X-ray diffraction measurements

Stress analysis on chemical vapor deposition (CVD) diamond films has demons trated an apparent disagreement among various researchers in recent works e ven for similar deposition conditions. The type and the value of stress hav e shown a strong dependence on film thickness, which can be attributed to c olumnar growth and grain size and boundaries. X-Ray diffraction techniques appeared to be more suitable to study these effects and permit the evaluati on of the average stress in larger sample areas when compared with micro-Ra man spectroscopy, which feels a local strain inside the grains. In the case of boron-doped diamond films, boron incorporation on substitucional or int erstitial sites can produce stresses according to the doping level. In orde r to investigate these effects, a series of diamond films were deposited on silicon (001) substrate in a hot filament (HF)-assisted CVD reactor at 800 degreesC. The CH4 flow is kept at 0.5 seem for all experiments and the H-2 and B2O3/CH3OH/H-2 flows are controlled in order to obtain the desired B/C ratios. Stress behavior in HFCVD boron-doped diamond films has been invest igated by X-ray diffraction measurements using the sin(2) psi technique. Te nsile and compressive stresses have been observed and the thermal and intri nsic components have been calculated. The diamond films were characterized by scanning electron microscopy and Raman spectroscopy. (C) 2001 Elsevier S cience B.V. Pdl rights reserved.