High rate deep Si etching for through-silicon via applications

Abstract

High rate deep Si etching for through-silicon via (TSV) applications is reported. The requirements for the Si etch process is discussed from the viewpoint of TSV size and productivity, and the effective processes are described. For “small” TSV a few microns in diameter and up to 10 μm deep, profile control is the most important requirement, For “large” TSV with diameters of more than 50 μm and depths up to 100 μm and more, an ultrahigh Si etch rate is indispensable. The “medium” TSV with diameters and depths several tens of microns requires both high etch rate and profile control. Capacitively coupled plasma MERIE at high pressure is shown to be effective, by using HBr gas chemistry for small TSV, and by using SF6 gas chemistry and high rf frequency for large and medium TSV where an extremely high etch rate can be obtained.