Development of Young's Modulus Measurement System for Anisotropic Thin Films

(1)采用三点弯曲振簧法测量了Cr薄膜的杨氏模量。厚度大于5.1 mm的薄膜的杨氏模量为248.8Gpa，与体材的杨氏模量吻合较好。小于3.2 μ m的薄膜的杨氏模量随薄膜厚度的减小而增大。0.248 μ m的杨氏模量为568GPa。(2) X射线衍射和扫描电镜观察表明，厚度小于1 ~ 2 μ m时形成无定形结构，厚度大于1 ~ 2 μ m时形成柱状结构。两种结构的厚度边界与杨氏模量随膜厚减小而增大的厚度边界吻合较好。(3)当薄膜厚度大于2.9 mm时，坡莫合金的杨氏模量为222.0GPa，与本体材料的杨氏模量基本一致。薄膜的杨氏模量随薄膜厚度的减小而增大。0.276 mum薄膜的杨氏模量为296GPa，是本体材料的1.48倍。(4)扫描电镜观察表明，杨氏模量随薄膜厚度的变化是由于薄膜结构的变化引起的。在厚度小于1 ~ 2 mm的范围内形成非晶状结构，在厚度小于1 ~ 2 mm的范围内形成柱状结构。

(1) Young's modulus of Cr thin films was measured by a three-points bending and vibrating reed method. The value of the Young's modulus of the film thicker than 5.1 mum was 248.8Gpa and which agrees well with that of Young's modulus of the bulk material. Young's modulus of the film thinner than 3.2 mum increased with decreasing the film thickness. Young's modulus of 0.248 mum was 568GPa.(2) X ray diffraction and SEM observation revealed that amorphous-like structure was formed in the thickness less than 1-2 mum while columnar structure was formed in the thickness thicker then 1-2 mum. The thickness boundary of the two structures was agrees well with the thickness at which Young's modulus increased with decreasing the film thickness.(3) Young's modulus of permalloy was 222.0GPa for the film thicker than 2.9 mum which agrees with that of the bulk material. Young's modulus of the film thinner than 1.1 mum increased with decreasing the film thickness. Young's modulus of 0.276 mum film was 296GPa which is 1.48 times larger than that of the bulk material.(4) SEM observations indicated that the variation of Young's modulus with film thickness was resulted from the change of the film structure. Amorphous-like structure was made in the thickness range thinner than 1-2 mum while columnar structure in the range thinner than 1-2 mum.