Fabrication and Properties of Ultra Small Si Wire Arrays by Vapor-Liquid-Solid Growth with Circuits

Penetrating micro-Si wire probe arrays with on-chip circuits have been developed using selective Vapor-Liquid-Solid (VLS) growth method for application to multipoint recording of neural activity potentials. The Si wire probes with 160 µm in length and 3.5 µm in diameter at tip were grown at predetermined positions for growth time of 2 hours at 700 °C. Resistivity of the Si wire probe grown by Au-Si2H6 VLS was 104 Ω·cm without impurity doping process. To achieve low impedance of Si wire probes for recording of neural potential levels, phosphorous thermal diffusion to Si wire probes was carried out. After diffusion at 1100 °C, Si wire probes showed resistivity of 10−2 Ω·cm, and the value is low enough to use the Si wire probe for applications to neuroscience field.