Fabrication and properties of ultrasmall Si wire arrays with circuits by vapor-liquid-solid growth

A micro-Si wire probe array chip with on-chip circuits has been developed for the applications on multichannel electrodes of neuroelectronic interface systems. Selective Au-Si2H6 vapor-liquid-solid (VLS) growth method provides a successful Si probe array on Si(1 1 1) wafers in predetermined positions and probe sizes. Si probes with 160 mum in length and 3.5 mum in diameter at tip were grown for 2 h at 700 degreesC. Moreover, the circular cone type shape of the Si probes was controlled by changing the Si2H6 gas pressures in the VLS growth. After wiring process for on-chip circuits on Si(1 1 1) wafers, the Si probes were grown perpendicular to the wafer surface by the VLS growth process. Conductivity of Si probes was controlled by using phosphorous diffusion, resulting in a resistivity of 10(-2) Omega . cm from 10(4) Omega . cm at a diffusion temperature of 1100 degreesC. In in vivo studies, penetrating micro-probe array with low impedance such as the VLS grown Si probes has been desired. Using the VLS grown Si probes, these electrical signals was detected successfully. (C) 2002 Elsevier Science B.V All rights reserved.