Ultra-thin resistors for piezoresistive sensors

Different ion implantation techniques for the fabrication of shallow boron doped layers used as piezoresistors have been evaluated. In the present case the corresponding process parameters have been optimized to meet demands for high deflection sensitivity of piezoresistive AFM cantilevers. Boron doped layers with decreased pn-junction depths down to ~ 20 nm has been fabricated showing increased deflection sensitivities of (10-20)x106 Ωm-1 compared to conventional implanted resistors. The used ion beam technique fulfills requirements for pn-junctions in terms of small junction depth and low sheet resistance. Additionally, the piezoresistor fabrication processes was evaluated in combination with other ion implanted elements integrated in AFM cantilevers.