Micro-beam tactile sensor for the measurement of vertical position displacement

Abstract

Abstract A piezoelectric tactile sensor is disposed on the end of a flexible silicon beam to sense contact of the beam by an object, such as a circuit chiplead, whose position is to be measured. A piezoelectric actuator is disposed on top of the beam, and a variable DC voltage is supplied to the actuator to cause the beam to deflect into an object whose position is to be measured. Processing circuitry senses the signal generated by the sensor in response to contact with the object, and determines the position of the object from the magnitude of the actuator voltage at that point. To increase the magnitude of the signal generated by the sensor, an AC voltage is also supplied to the actuator to cause the beam to vibrate at a harmonic frequency. A plurality of the beams can be etched from a single wafer of silicon and utilized to simultaneously measure the positions of a plurality of circuit chipleads. The fabrication technique used for forming the beams utilizes a plurality of photolithographic steps to form the beam from a silicon wafer. Due to the fragile nature of the beams once they have been etched, bonding pad areas for the sensor electrodes are formed on the wafer prior to the actual etching of the beams from the wafer. The images of the bonding pad areas are stored on the wafer by covering them with a plurality of protective layers. Once the beams have been etched, the bonding pad areas can be reexposed by simply removing the protective layers without any further photolithographic steps that might damage the beams.

Inventors

• 👤 Garry W. Woodruff
• 👤 Johannes G. Smits

Bibliographic Details