Young's Modulus Measurement of Thin Films for Electric Devices

为了测量薄膜的杨氏模量，开发了高分辨率三点弯曲机和高分辨率共振测量机。该仪器可以测量杨氏模量，精度达到三级，并经初步试验证实。 1．使用三点弯曲机测量Co-Ta-Zr薄膜的杨氏模量。薄膜的厚度范围为10微米至1微米。厚度大于3.5微米的薄膜的杨氏模量为150GPa，而厚度小于3.5微米的薄膜的杨氏模量随着厚度的减小而增加。 1微米厚薄膜的杨氏模量为250GPa，约为4.5微米厚薄膜的1.7倍。通过弹性应变能和表面能的能量平衡讨论了杨氏模量随厚度减小而增大的情况。 2． Cr薄膜的杨氏模量采用共振法测定。 Cr薄膜和Co-Ta-Zr薄膜的杨氏模量均随着薄膜厚度的减小而增大。 4．根据上述证据，得出结论：在临界厚度处，薄膜的杨氏模量随着薄膜厚度的减小而增加。

For measuring the Young's modulus of thin films, a high resolution three-points bending machine and a high resolution resonance measuring machine were developed. These machines could measure the Young's modulus with three order accuracy, which was confirmed by preliminary tests.1. Young's modulus of Co-Ta-Zr thin film was measured by using the three-points bending machine. The thickness of thin films was ranged from 10 micron meter to 1 micron meter. The Young's modulus of the films thicker than 3.5 micron meter was 150 GPa but that of the films thinner than 3.5 micron meter is increased with decreasing thickness. Young's modulus of 1 micron meter film in thickness is 250 GPa which is about 1.7 times of 4.5 micron meter film in thickness. The increase in Young's modulus with decreasing thickness was discussed by the energy balance of elastic strain energy and surface energy.2. Young's modulus of Cr thin film was measured by resonance method. Young's modulus of Cr thin films is increased with decreasing film thickness as well as Co-Ta-Zr films.4. Form the above evidence, it is concluded that the Young's modulus of thin films increases with decreasing film thickness at a critical thickness.