Improving uniformity in high aspect ratio through-silicon vias through spectral reflectometry for etch process control

Three-dimensional chip stacking using through-silicon via (TSV) technology is a major focus in semiconductor manufacturing. However, with the increasing demand for higher etching rates in 3D integration for high-volume manufacturing process, achieving a uniform etch across the wafer becomes crucial. We have developed an in-house spectroscopic reflectometry module to provide a non-destructive, rapid metrology solution for in-line monitoring of wafer etch uniformity. It can be integrated into the etch process to monitor full wafer TSV depth variations in real time. Experimental trials utilizing a deep reactive ion etch process, guided by reflectometer feedback data, have effectively improved etch depth uniformity of TSVs with a nominal 5-μm critical dimension and aspect ratio of 10, reducing variations from 5.18% to 2.47%.