连续刚度法对单晶硅片的力学性能的表征

利用纳米压痕仪通过连续刚度测量法对单晶硅片在压入过程中的接触刚度、硬度、弹性模量进行了连续测量.结果表明:当接触深度在20～32 nm左右时,单晶硅片的接触刚度与接触深度成直线关系,硬度和弹性模量基本保持不变,此时所测得的是单晶硅片表面氧化层的硬度和弹性模量,分别约为10.2 GPa和140.3 GPa.当接触深度在32～60 nm左右时,单晶硅片的接触刚度与接触深度成非直线关系,硬度和弹性模量随接触深度急剧增加,表明单晶硅片表面氧化层的硬度和弹性模量受到了基体材料的影响.当接触深度在60 nm以上时,单晶硅片的接触刚度与接触深度成直线关系,硬度和弹性模量基本保持不变,测得值为单晶硅的硬度和弹性模量,分别约为12.5 GPa和165.6 GPa.

MECHANICAL PROPERTIES OF SILICON WAFER CHARACTERIZED BY CONTINUOUS STIFFNESS MEASUREMENT TECHNIQUE

The contact stiffiness, hardness and elastic modulus of silicon wafers were continuously measured during the loading portion of an indentation test by a nanoindenter apparatus with the continuous stiffiaess measurement technique. The results show that when the contact depth is 20-32 nm, the relationship of the contact stiffness of the oxide coating on the surface of the silicon wafer with the contact depth is linear, and the hardness and elastic modulus remain constant at 10.2 GPa and 140.3 GPa respectively. When the contact depth is 32-50 nm, the relationship of the contact stiffiaess with the contact depth is not linear, and the hardness and elastic modulus increase rapidly with the contact depth. It is shown that the hardness and elastic modulus of the oxide coating on the surface of silicon wafer are affected by the bulk material. When the contact depth is over 60 nm, the relationship of the contact stiffiaess of the silicon wafer, e.g., the bulk material, with the contact depth again is linear, and the hardness and elastic modulus stay constant at 12.5 GPa and 165.6 GPa, respectively.