High-density silicon microprobe arrays for LCD pixel inspection

A novel structure and fabrication methods of high-density silicon microprobes have been developed for use in the pixel-wise inspection of flat-panel screens. The microprobe array consists of 101 parallel cantilever-beam springs, fabricated by an anisotropic etching of (110) silicon wafers. Each microbeam contains a hemispheric gold probe-tip for one-to-one electrical contact with high-density flat-panel electrodes, metal lines for pixel-wise electrical signal drive, and self-diagnostic structures for beam breakage detection. The dimensions of the microprobe array have been decided to meet a series of design constraints, including geometric and strength requirements, microfabrication constraints and the admissible ranges of contact forces, obtained from preliminary experiments. An integrated fabrication process has been developed based on surface-micromachining, electroplating, and bulk-micromachining processes with an etch-rate based corner compensation technique. The fabricated microprobe array has been applied to the probing of high-density electrodes on the 640×480 STN-LCD panel, resulting in stable electrical contacts for an applied load of 2g _f per microbeam