Micro-raman study of mechanical stress in polycrystalline silicon bridges

摘要

Micro-Raman spectroscopy is used to study mechanical stress distribution in polycrystalline silicon bridges on cavities micromachined in crystalline Si wafers. The influence of the processing parameters such as the thickness of polycrystalline membrane, the annealing conditions (before or after removal of the sacrificial porous-Si layer), are studied. The results indicate that the annealing reduces the residual stress by an order of magnitude and that the membrane thickness of 2.5 mu m has the least residual stress.