Diamond-like carbon for MEMS

Sputter-deposited amorphous diamond-like carbon (DLC, a-C) on silicon has been investigated with respect to micro electro mechanical systems (MEMS) applications. Sputtered a-C with a content of diamond-like sp(3) bonded carbon of around 25% showed a high hardness of up to 30 GPa. Self-supporting cantilevers of 0.5 mu m in thickness, several hundreds of mu m in length and some tens of mu m in width have been successfully realized using lift-off patterning of DLC and anisotropic silicon etching. The mechanical properties of DLC (Young's modulus, stress, stress gradient fracture strength) were characterized by cantilever deflection analyses. DLC strain gauge resistors integrated on micromachined silicon boss membranes were investigated under tensile and compressive loading. Piezoresistive gauge factors in the range of 20-30 were observed at temperatures between room temperature and 50 degrees C.