Effect of Grain Size and Holding Load on Nanoindentation Creep of Cu Film
晶粒尺寸与保载载荷对Cu膜纳米压入蠕变性能的影响

The effects of grain size and holding load on creep properties of polycrystalline Cu thin films were investigated using nanoindentation instrument. The results show that when grain size of polycrystalline Cu thin films is between 200 nm to 1500 nm, the stress exponent is insensitive to grain size. However, when the grain size is reduced below 200 nm, the stress exponents increases with decreasing grain size, implying that there is a critical grain size for stress exponents in nanoindentation tests. The stress exponent also increases with the increase of holding load. The above phenomena result from more grains to be involved and the creep rate decrease due to dislocation strengthening the plastic zone under the indenter tip.