Through-silicon-via process control in manufacturing for SiGe power amplifiers

Through-silicon-via (TSV) technology is conceptually simple, but there are many process control issues in volume manufacturing. An important parameter is TSV depth, because the product yield will be reduced if TSV depth is either too shallow or too deep. Recently, it has been shown that TSV depth can be measured using an interferometric sensor operated at infrared (IR) wavelengths. In this paper, we demonstrate that small variations in TSV depth (<; 5 μm) can be monitored across a wafer. This allows for quick feedback and adjustments to the TSV process, thereby ensuring high yield on the final product.