PVA Tepla and Imec Demonstrate 3-D TSV Void Detection using GHz SAM
January 21, 2013. Imec and PVA Tepla have presented results regarding the detection of TSV voids in 3-D stacked IC technology. After having applied scanning acoustic microscopy (SAM) to temporary wafer (de)bonding inspection, researchers successfully used new advanced GHz SAM technology to detect TSV voids at wafer-level after TSV copper plating. Together, they will continue to investigate the applicability of high-frequency scanning acoustic microscopy for nondestructive submicron void detection.
The initial focus of the collaboration was on developing metrology aimed at detecting voids after temporary wafer bonding, allowing for proper rework of 3-D wafers. Temporary wafer (de)bonding and thin-wafer handling remains challenging for 3-D stacked IC technology. The development of interface particles and voids during the temporary bonding process has a detrimental impact on the subsequent wafer-thinning process steps, affecting the wafer thinning performance as well as long-term tool stability and performance. PVA Tepla and imec have developed an automated foup-to-foup (front opening unified pod), wafer-level process based on 200-MHz scanning acoustic microscopy using Tepla’s AutoWafer 300 tool.
After demonstrating nondestructive detection of interface particles and voids, imec used PVA Tepla’s high-resolution capability GHz-frequency SAM tool to successfully detect voids in TSVs of 5 µm diameter and 50 µm depth, immediately after plating. Future work will concentrate on further refining the process and implementing GHz SAM capability to increase the spatial detection resolution. Moreover, imec and PVA Tepla will investigate the applicability of GHz SAM to detect submicron voids in TSV and to investigate other aspects related to 3-D technology, such as bump connection quality.