A simple post-processing technique allowing Cu inductors to be added to integrated circuits fabricated in technologies providing only Al metallization is presented. The inductors use a 4-m thick electroless plated Cu layer to minimize resistance, and are formed over a 9-m thick polyimide dielectric to reduce substrate losses. Inductors optimized for 2.5-GHz had as high as 17. The effectiveness of the post-processing technique is demonstrated by application to a voltage-controlled oscillator (VCO) fabricated in a commercial bipolar technology with Al metallization. Circuits with post-processed Cu inductors gave a phase noise of 106 dBc/Hz at 100 kHz offset from a 2-GHz carrier, while control circuits with Al inductors gave a phase noise of only 101 dBc/Hz at 100 kHz offset from a 1.8-GHz carrier and had higher power consumption.
The optical processes involved in laser trapping and optical manipulation are explored theoretically and experimentally as a means of activating a micrometer-size gear structure. We modeled the structure by using an enhanced ray-optics technique, and results indicate that the torque present on the gear can induce the gear to rotate about the gear-arm plane center with light as the driving energy source. We confirmed these findings experimentally by using gears manufactured with conventional semiconductor techniques and from a layer of polyimide. It is expected that such a simple gear design activated by use of light could lead to an entire new class of micro-optical-electromechanical systems.
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