Low frequency tantalum electromechanical systems for biomimetical applications

The integration of p-channel metal-oxide-semiconductor transistors and tantalum bridge structures for the fabrication of resonant gate transistors (RGTs) that operate in the audible frequency range has been developed. Resonant gate transistors with channel length of 15 μm and clamped-clamped tantalum bridges of 0.5 mm to 1.6 mm in length have been fabricated. The measured first modal frequency of the bridges has been found to be higher than the expected theoretical value. From the experimental and theoretical analysis of the first three modes, the stress in the bridges has been extracted and found to be tensile with values of 3 MPa - 10 MPa. Finite element simulation has validated the extracted stress and the mode shapes of the tantalum bridges. The modulation of conductance in the channel region between the source and drain by the tantalum bridge of the RGT has been demonstrated. The threshold voltage and transconductance of the fabricated p-channel RGT have been measured to be -37 V and 6.84 μS, respectively.