内应力对金属薄膜生长织构的影响

基于FS型原子镶嵌势（EAM热）用分子动力学模拟了金属多晶薄膜的原子沉积生长过程，通过预设恒定应变在薄膜生长过程中引入了单轴压应力，模拟研究了应力对呈丝织构的多晶薄膜中沿丝轴旋转取向择优的影响，模拟结果表明，在固定压应变条件下，最密排方向偏离压应力轴的晶粒较为优先生长发展；在生长过程中，取向择优的晶粒从沉积表面开始逐渐扩张吞并相邻晶粒，模拟结果还显示，这种生长织构的发展随沉积膜厚增加有显著的临界特征，在织构发展过程中被吞并的晶粒局部出现孪晶，继而转换为择优生长晶粒的结构，在被吞并的晶粒最终消失处将会留下失配位错。

EFFECT OF INTERNAL STRESS ON GROWTH TEXTURE OF METALLIC THIN FILMS

Molecular dynamics simulations of depositional growth processes of polycrystalline metal thin films have been carried out, in which an FS type embedded atom method (EAM) potential was used. With a preset fixed strain, a uniaxial internal compressive stress was introduced during the film growth, and the effect of internal stress on development of growth texture of thin films was simulated. The results show that internal stress does significantly affect the orientation preference of the grains in films. The stress-induced preferential development of the favored grain starts at the deposition surface and expands by consuming its neighboring grains. Under fixed compressive strain, the grains, of which the close packing direction orients away from the compressing axis, grow preferentially. The simulation has also revealed a critical feature in kinetics of such stress-induced texturing versus film thickness. Local twinning was found to occur in the shrinking grain, and the twin soon transferred to the structure of the expanding grain. After the expansion completed, a mismatch dislocation may be left at where the shrinking grain disappears.