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Major efforts are currently underway throughout the IC industry to develop the capability to integrate device chips by stacking them vertically and using through-silicon vias (TSVs). The resulting interconnect density, bandwidth, and compactness achievable by TSV technology exceed what is currently possible by other packaging approaches. Market-driven applications of TSV involving memory include multi-chip high-performance DRAM, integration of memory and logic functions for enhanced video on handheld devices, and stacked NAND flash for solid-state drives. High-volume commercial implementation of 3D TSV is imminent but faced by special challenges of design, fabrication, bonding, test, reliability, know-good die, standards, logistics, and overall cost. The main focus of this paper is the unit-process and process-integration technology required for TSV fabrication at the wafer level: deep silicon etching, dielectric via isolation, metallization, metal fill, and chemical-mechanical polishing.