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The research studied the degrading and consuming phenomena of organic additives caused by oxygen generated by the insoluble anode in the process of copper electroplating. A double-layer anode bag was designed to prevent the additive ions from approaching the anode and getting degraded. Nitrogen bubbles of a particular size were injected into the anode bag gap to help capture dissolved oxygen molecules and merge with tiny oxygen bubbles coming from the anode. Therefore, the total surface area and number of oxygen bubbles were reduced, the oxygen concentration in the merged bubbles was diluted, and the amount of dissolved oxygen in the electrolyte was lowered. The improved design of anode bag with nitrogen purging slowed down the degrading rate and elongated the working life of the additives, and thereby cut down the production cost. In addition, a recycle system was designed to remove oxygen from nitrogen for reuse of nitrogen.

We have demonstrated a wireless hydrogen sensing system using commercially available wireless components and AlGaN/GaN High Electron Mobility Transistor (HEMTs) differential sensing diodes as the sensing devices. The active device in the differential pair is coated with 10 nm of Pt to enhance catalytic dissociation of molecular hydrogen, while the reference diode is coated with Ti/Au. Our sensors have a wide range of detection from ppm levels to ~30%, with the added advantages of a very rapid response time within a couple of seconds, and rapid recovery. The sensors have shown good stability for more than 18 months in an outdoor field test.