Design and characterization of NCD piezoresistive strain sensor

Nanocrystalline Diamond (NCD) is a very promising material for fabrication of high-temperature devices because of its unique mechanical and electrical properties. The prospective of using diamond is not only in sensors (MEMS) but in RF and power electronic as well. The strain gauges based on nanocrystalline diamond layers have been successfully designed and fabricated using mainly domestic technological background. The CoventorWare FEM calculations of the mechanical stress and geometrical deformations of a 3-D structure are used for a proper localization of the piezoresistor on the carrying substrate. The boron-doped piezoresistive sensing element was realized using a directed patterned growth of NCD film on SiO₂/Si by microwave plasma enhanced chemical vapor deposition (CVD). Cantilever beam configuration was used for sensor characterization. The sheet resistance of tensometric layers as well as contact edge resistivity were measured by Transmission Line Method (TLM). The gauge factor of boron-doped NCD films was investigated in the range from room temperature up to 250degC and from 0 to 1 N of applied force.