ReVia is a new endpoint detection (EPD) technique that can monitor the progress of “via reveal” etch processes even at remarkably low (<0.01%) via densities. It is a unique solution that can significantly increase yields for device manufacturers involved in emerging 3D packaging applications utilizing through-silicon vias (TSVs).
Via reveal substrates typically have a low via density and conventional EPD techniques cannot detect the revealed via tips. For “soft reveal” applications, the point at which the vias are revealed varies due to Total Thickness Variation (TTV) of incoming ground wafers. Without endpoint, the user has to independently measure the silicon thickness above the TSVs on every wafer and adjust the etch time accordingly.
ReVia has been successfully demonstrated and validated on a variety of bonded TSV wafers from many leading packaging houses and IDMs, allowing implementation of production-worthy soft reveal solutions. The point at which the TSV tips are revealed is clear in the data output, enabling a consistent reveal height from one wafer to the next. This increases yields, avoids scrap and saves the device manufacturer both time and money at a point in the fabrication process where the wafers have an extremely high value.