The idea of using through-silicon-via (TSV) technology has been around for many years. However, this technology has only recently been introduced into high volume manufacturing. This paper gives a comprehensive summary of the TSV fabrication steps, including etch, insulation, and metallization. Along with the backside processing, assembly, metrology, design, packaging, reliability, testing and yield challenges that arise with the use of TSVs. Benefits and drawbacks for using each approach to manufacture TSVs are discussed including via-first, via-middle, and the via-last process. Several applications for TSVs are discussed including memory arrays and image sensors.