Smart Metrology Control of Through Silicon Via Etching Process for High End Devices

Abstract

In this paper, we report on an innovative process characterization solution that aims to control the uniformity of the Through Silicon Via (TSV) etching process. The solution relies on measuring complementary geometric characteristics of the open Through-Silicon-VIA (TSV) that are key to establish a reliable vertical interconnection. When TSV are fabricated either in high-density matrix or in isolated locations, the solution presented here allows the non-destructive reliable measurement of top / bottom diameter, depth, and thickness of top hard mask layer with a combination of optical techniques. As example of use case, we present the result of the characterization of three different products hosting TSV with top diameter as small as 3 μm and aspect ratio up to 17:1. The new methodology is compared to the state of the art of metrology control solutions used in the semiconductor industry.