The interface structure between diamond-like carbon (DLC) and a silicon substrate was modified by application of rf substrate bias immediately before film deposition during magnetron sputtering. Results clarified that the oxide layer on silicon was removed while the mean roughness of the substrate surface was maintained at around 0.1 nm at 300 V or greater negative bias voltage. A ball-on-disk test revealed that this pretreatment increased the abrasion-proof length by a factor of 20. Cross-sectional Auger electron spectroscopy and X-ray photoelectron spectroscopy revealed formation of a mixed layer of carbon and silicon at the interface.
Recently, via-filling for the build-up plating process has been studied actively using three organic micro additive agents: polyethylene glycol 4000 as a carrier, bis-(sodium sulfopropyl)-disulfide as a brightener, and Janus Green B as a leveler. Added amounts of these agents are usually used between 10-50 ppm. The filling ability becomes greatly reduced and defective conformal deposition is generated if the concentration of the additives is not used in the proper range. However, simple analytical methods of these additives have remained elusive. Therefore, we attempted to analyze these additives using flow injection analysis (FIA) with boron doped diamond (BDD) as an electrochemical detection electrode at high applied potential (+2.1 V vs. Ag/AgCl). Results showed that these additives are detectable using elution solutions of FIA to produce high signal and low noise detection. In this report, we describe an easy analytical method for via-filling additives using FIA with BDD.
For zinc electroplated from a bath consisting of zinc chloride and ammonium chloride, we investigated the influence of some commercial brighteners on crystal growth and surface morphology. The bath was developed for formation of chrome (III) hydroxide type chemical conversion coatings, which contribute high corrosion resistance to zinc films. With increasing concentration of brighteners and cathode current density, the overpotential increased and the zinc deposits changed from a gray to a brighter appearance. Over the critical concentration of brighteners, zinc deposits invariably showed the preferred orientation of 10·1 plane and 10·0 plane in accordance with Pangarov's view. Especially, the latter plane might be a twin crystal formed along the twin boundary of the 10·2 plane on 00·1 plane of electroplated zinc. Increased concentration of the brighteners did not change the preferred orientation greatly, but it did reduce the grain size of zinc deposits.