Abstract: A plasma processing system has a chamber, a workpiece holder in an interior of the chamber, a first power circuit, a second power circuit, and a feedback circuit. The first power circuit has a first power supply coupled to a first matching network. The first matching network is coupled to a coil adjacent to the chamber. The second power circuit has a second power supply coupled to a second matching network. The second matching network is coupled to the workpiece holder. The feedback circuit includes a radio frequency (RF) probe and a controller. The RF probe is partially disposed in an interior of the chamber. The controller is coupled to the RF probe and the first power circuit. The RF probe measures a change in plasma density in the interior of the chamber and the controller adjusts the first power supply in response to the change in plasma density.

Abstract: An ultrasonic sensing array having ultrasonic transducer elements formed on a micromachined single-crystal semiconductor wafer provided with a deep recess under each transducer. Etch-altering dopants are diffused into the wafer to form rimmed support structures for dielectric stress-balanced elements. Composite dielectric layers are grown on both surfaces of the wafer. One composite layer serves as a diaphragm underlying the transducer elements. The other composite layer serves as a mask for etching away the substrate under each transducer element to form the deep recess while leaving the support structures and diaphragm layer. The resulting hollow or recess under each transducer element reduces the parasitic capacitance between the transducer and support substrate. The transducer elements are made by forming conductive bottom plates on the dielectric diaphragm layer, adding a piezoelectric polymer layer and thereafter forming the conductive top plates.

Abstract: An ultrasonic sensing array having ultrasonic transducer elements formed on a micromachined single-crystal semiconductor wafer provided with a deep recess under each transducer. Etch-altering dopants are diffused into the water to form rimmed support structures for dielectric stress-balanced elements. Composite dielectric layers are grown on both surfaces of the wafer. One composite layer serves as a diaphragm underlying the transducer elements. The other composite layer serves as a mask for etching away the substrate under each transducer element to form the deep recess while leaving the support structures and diaphragm layer. The resulting hollow or recess under each transducer element reduces the parasitic capacitance between the transducer and support substrate. The transducer elements are made by forming conductive bottom plates on the dielectric diaphragm layer, adding a piezoelectric polymer layer and thereafter forming the conductive top plates.