Jet electrochemical deposition (JECD) plating was found to be very beneficial for void-free Cu filling of very narrow openings with large aspect ratios. The most demanding void-free filled trenches were 0.16μm wide and 1.4(μm deep, with aspect ratio of ～8.75:1. The JECD allows high speed plating, up to ～2.8 μm/min. Surface smoothness improves with the plating rate, achieving full bright deposits at the higher speeds. The bright deposits do not display the deleterious spikes (or "balloons") and elevation steps at transitions from flat field to patterned dense arrays of small openings, usually found after Cu plating. The JECD allows a wide process latitude, more than 100% of the bath additives. This paper suggests a plausible model and mechanism to explain the beneficial JECD effects. In addition, a new proprietary seed layer provides excellent surface conduction on the field (required for good wafer uniformity and void-free filling), while occupying the minimum space inside the openings. This seed layer was deposited on 0.10um wide trenches with aspect ratio of ～14:1. The combined (Cu) seed layer plus barrier layer were ～1,900A thick on the field, but only ～400-500A thick on the trench sidewalls and bottom surfaces, with uniform and excellent step coverage.
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