Abstract
We investigated the residual stress in diamond films grown on molybdenum substrates as a function of different places in the same large sample. The diamond film wafers of Ф60 mm diameter were deposited at 900°C by high power DC arc plasma jet CVD method using a gas mixture of methane (1.8% vol.) and hydrogen ( 90% vol.). The grain sizes, obtained from the top view scanning electron microscopy (SEM) images, were found to become larger from center to the border in the same sample, and the x-ray diffraction indicated that the intensity of characteristic spectroscopy in same diamond film was changed from (220) to (111) with the increases of (311). Profile curves presented the appreciable difference of surface texture from center to edge. The film had 4.3GPa of residual compressive stress. Examination of the Raman spectra of the film revealed that residual stress in the film of up to approximately 0.70GPa, and the Raman spectroscopy shifts from 1332.99cm-1 at the center to 1331.17cm-1 at the border, which means the stress mode changed from compressive to tensile. These demonstrated a significant inhomogeneity of stress in diamond films. The differences have been attributed partly to high temperature inhomogeneity arc jet during growth and morphological aspects of the film growth. The relationships between stress and methane concentration, and substrate temperature are discussed in detail.
Published Version
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