Measurement Of The Mechanical Properties Of The MEMS Materials

The mechanical properties of thin films are fundamental parameters of practical and theoretical importance in the MEMS and microelectronics fields, and this also falls into this paper's investigation. Two kinds of instruments, the commercially available nanoindenter and a custom designed optical balance, are utilized.Two methods are employed to evaluate the mechanical properties using a nanoindenter. Series of indentations are carried out under the standard Berkovich tip on several extensively used materials, and their Young's moduli & nano hardness are extracted. The tested materials include (100) silicon wafer, (110) silicon wafer, poly-silicon thin film, dry oxidized silicon dioxide thin film, wet oxidized silicon dioxide thin film, LTO thin film, standard LPCVD silicon nitride film, low stress LPCVD silicon nitride film, alumni nitride film, zinc oxide film etc. In the nanoindentation experiment of the single crystal silicon, two different mechanical phases are observed at different indentation depth. In the other method, Young's modulus, residual stress, and bending strength are characterized under a wedge tip by means of micro bridge deflection tests. Both the effect of substrate deformation and the state of large deflection of the microbridge are involved in the theoretical expression. Furthermore, the distribution of axial stress in the micro bridge is discussed in detail by taking different shapes of cross section into consideration. And a shape factor is introduced into the expression, which simplifies the theoretical expression.The Young's modulus, Shear modulus and bending strength of single crystal silicon are characterized by the balance approach, too. A simplified relative uncertainty transfer equation is obtained by introducing the appropriate non-dimensional factor into the expression, thus providing more convenience to the practical evaluation of the resultant uncertainty.