Accurate Depth Control of Through-Silicon Vias by Substrate Integrated Etch Stop Layers

In this work, the development of engineered silicon substrates for a novel via-middle TSV integration concept is demonstrated. These substrates include 3D buried etch-stop layers which provide both an ideal vertical and lateral etch-stop for TSV trench etching thus enabling the simultaneous realization of different size of TSVs on the same silicon substrate. Beside standard BiCMOS and TSV fabrication steps, only a low-temperature fusion bonding process is applied and the integration concept is realized without adding an additional mask to the established BiCMOS via-middle TSV technology. As a result, the developed technique is very promising to realize different dimensions of TSVs on the same substrate for future smart system applications.