纳米金刚石薄膜的微结构和残余应力

MICROSTRUCTURE AND RESIDUAL STRESS IN NANOCRYSTALLINE DIAMOND FILM

采用双偏压热丝化学气相沉积法在不同栅极和衬底偏流下制备出纳米金刚石薄膜.采用Raman谱、SEM、AFM、纳米压痕法和XRD分析纳米金刚石膜的微结构、弹性模量和残余应力.分析结果表明,金刚石晶粒尺寸随着栅极和衬底偏流的增加而减小,而衬底偏流的加入会引起非金刚石成分的显著增加.金刚石晶界的畸变使得弹性模量随着栅极和衬底偏流的增加而减小,薄膜热应力也随之减小.晶界非金刚石成分引起金刚石本征应力呈压应力性质,晶界密度的增加使得本征应力随着栅极偏流的增加而增加,但衬底偏流引起薄膜抵抗变形能力剧烈下降,导致金刚石本征压应力的减小.

Nanocrystalline diamond films were prepared at different grid and substrate bias currents in a double bias hot filament CVD system. The microstructures of the films were analyzed by Raman spectrometry, SEM and AFM, and the elastic modulus and residual stresses were measured by nano-indentation and XRD method. The results show that the increases of grid and substrate bias currents will cause the decreases of grain size, elastic modulus and thermal stress, and the increase of sp2 non-diamond content, which will induce an intrinsic compression stress in the film. The grid bias current results in the increase of intrinsic stress as grain boundary increased. But the substrate bias current leads to the weak ability of resistance to deformation as existed a lot of non-diamond content in the grain boundary, which results in decreasing of intrinsic stress.