Fabrication and testing of CVD diamond single-material MEMS resonators with piezoresistive detection

Using piezoresistive detection and piezoelectric actuation, the fabrication and testing of polycrystalline diamond based single-material MEMS (SMM) resonators, with a resonant frequency of 48.2 KHz and a quality factor of 160 in air, is reported for the first time. A 0.6-μm-thick boron-doped poly-C with a resistivity of 9 Ω·cm is used as a piezoresistor. A 50-nm-thick highly-doped poly-C inter-layer, with a resistivity of 5×10^-3 Ω·cm, was used between the metal and the piezoresistor to reduce the contact resistance. A 3-μm-thick undoped poly-C film, with a resistivity >; 10⁹ Ω·cm, was used as an insulating as well as a structural material.