Hexsil tweezers for teleoperated micro-assembly

This paper describes essential components of a prototype system for teleoperated microassembly. High aspect ratio molded polysilicon (hexsil) tweezers with integrated in-situ phosphorous doped thermal expansion actuator beams and piezoresistive polysilicon strain gages for tactile feedback are described. The tweezers are normally closed, and require 75 mW to open 35 μm. Piezoresistor performance remains to be measured. Metal lines on surface polysilicon flexible electrical interconnects bridge between rotating rigid hexsil beams. Surface polysilicon tweezer tips provide compliance suitable for force-controlled micromanipulation. The task demonstrated is the pick and placement of a 1 μm×4 μm×40 μm peg in a 4 μm×4 μm hole. The test parts used were surface micromachined SiO₂ and polysilicon beams held in organized arrays on the silicon wafer by break-away photoresist tethers