Through-chip electrodes for three-dimensional packaging can offer short interconnection and reduced signal delay. Formation of suitable vias by electrodeposition into cavities presents a filling problem similar to that encountered in the damascene process. Because via dimensions for through-chip filling are larger and have a higher aspect ratio relative to features in damascene, process optimization requires modification of existing superconformal plating baths and plating parameters. In this study, copper filling of high-aspect-ratio through-chip vias was investigated and optimized with respect to plating bath composition and applied current wavetrain. Void-free vias 70 m deep and 10 m wide were formed in 60 min using additives in combination with pulse-reverse current and dissolved-oxygen enrichment. The effects of reverse current and dissolved oxygen on the performance of superfilling additives is discussed in terms of their effects on formation, destruction, and distribution of a Cu͑I͒ thiolate accelerant.

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Methanol steam reforming reaction over copper on silicon carbide (Cu/SiC) catalyst was investigated in the production of hydrogen for fuel cell applications. Catalytic performances (activities, hydrogen production amount and concentration of carbon monoxide (CO)) were highly dependent upon the calcmation temperature of the catalyst. The calcmation at the temperature below 1073K in air leads to formation of amorphous silica (SiO2) layer on the surface of the catalyst, which stabilizes Cu active sites against sintering during reactions.

The optimized electrodeposition condition of via filling was obtained with the potential measurement. This measurement corresponds well with via cross section. We adopted two step electrodeposition method. The first step is via filling by the periodical-reverse pulse current of I on / I rev / I off = -20/ 40 / 0 [mA/cm 2 ] and T on / T rev / T off = 200 / 10 / 200 [ms]. Thirty minutes periodical-reverse pulse current perfectly fills the via of 40µm in diameter and 25µm in depth. The second step is etching by the periodical-reverse pulse current of I on / I rev / I off = 20/ -40 / 0 [mA/cm 2 ] and T on / T rev / T off = 200 / 10 / 200 [ms], in order to etch the copper film. Nine minutes was required to etch. The via are perfectly filled and the uniform via surface of 6 to 7[µm] was obtained within 39 minutes.