a process for fabricating an integrated circuit sensor / actuator is described . high aspect ratio deep silicon beams are formed by a process of deep trench etch and silicon undercut release etch by using oxide spacers to protect the silicon beam sidewalls during release etch . an oxide layer is then formed , followed by deposition of a controlled thickness of polysilicon which is then thermally oxidized . the polysilicon layer inside the trenches gets fully oxidized resulting in void - free trench isolation . this process creates a silicon island or beam on three sides leaving the third side for interfacing with the sensor / actuator beams . the sensor / actuator is formed by a similar process of deep trench etch and release etch process on the same substrate . these suspended beams of the sensors and actuators are bridged with the silicon islands from the fourth side . the above process finally results in suspended silicon beams connected to electrically isolated silicon islands .