凸结构的形成-低载下单晶硅表面的划痕损伤研究

Formation of Hillock-Scratch Damage on Si(100) Surface under Low Load

利用纳米划痕仪及曲率半径为3μm的球形金刚石针尖,在单晶硅(100)表面进行了不同载荷下的划痕试验.结果表明:随载荷的增加,单晶硅表面的划痕损伤先后经历了从凸起形成、凸起与凹槽并存到材料去除的变化过程.当载荷为0.5～3.0mN时,单晶硅上的划痕损伤表现为凸结构的形成,且凸起的高度和体积随载荷的增加而增大;当载荷为3～50mN时,凸起和凹槽同时出现,但损伤区域体积未见减少,损伤仍以凸结构形成为主导;当载荷大于50mN时,凹槽深度和磨损体积明显增大,划痕损伤表现为典型的材料去除.进一步的分析显示,单晶硅的划痕损伤特征与其接触区的应力状态密切相关,低载下的摩擦剪切是凸结构产生的主要原因.

Using a spherical diamond tip of 3 p,m in radius and nano - scratch instrument, the scratch tests were carried out on St（100） surface under various loads. It was found that with the increase in the load, the scratch damage on Si （100） surface would experience the following three stages： formation of surface hillock, generation of hillock and groove, and removal of material. While the load varied between 0.5 and 3 mN, the scratch - induced damage was identified as the formation of hillock. As the load increased from 3 to 50 raN, the scratch could lead to the generation of groove. However, the surface hillock kept growing and the hillock still dominated the scratch process. When the normal load attained 50 mN, the depth of the scratched groove increased rapidly and materials removal began to govern the scratch process. Further investigation revealed that the scratch - induced damage of Si （ 100 ） was associated with the contact stress between the diamond tip and St（100） surface. The formation of silicon hillock could be mainly attributed to the mechanical interaction by scratching under ultra low load.