Fabrication technology of CMOS-MEMS probe chip compatible with electroless nickel plating process

Abstract

In this study, we use the standard TSMC 0.35 μm 2P4M process to design CMOS-MEMS probe chip. MEMS technology involves the following steps such as lithography process, electroless nickel (EN) plating process, grinding process and dry etching process. The probe chip has through silicon via (TSV) package structure, and the combination of CMOS process within the multi-layer interconnections, which could assist the connection between the probes head the external devices, and reduce the difficulty of wiring layout. In addition, passive components or circuits could be integrated with the CMOS chip to improve the frequency bandwidth and measuring quality. So far, MEMS probe exist a shortcomings that are not able to be integrated with the CMOS process, and the testing cost. The finite element method was adapted to design of probe shapes and sizes. The LIGA-like thick photoresist process and EN plating technique was used in this study, Ni-P alloy to increase the thickness of the cantilever probe to strengthen its support strength were also applied. When the probe cantilever through the EN plating of deposition time, the uneven surface was appeared, each layer structure is used by polishing process to achieve the surface coplanarity. Finally, the probes structure were suspended by the dry etching process (RIE, ICP-RIE), and this study successfully fabricated chips forming one of the probe.