12.12 Final.2025

Abstract
Scaling interconnects to increase device density is a critical bottleneck for a range of applications in the 3D and advanced packaging fields. Currently, interconnect density is limited by, among other things, the ability to produce reliable, low resistivity Cu vias at high aspect ratios (AR). While some progress has been made, single side deposition, used in blind vias, is limited to 8:1 or 10:1. This limit is enforced by the adhesion and/or nucleation layer required for successful Cu electrochemical deposition (ECD). Current techniques provide high quality layers, but those layers are applied in a non-conformal fashion, leading to device failure at high AR or in reentrant features. Atomic layer deposition (ALD) is a vapor-phase deposition technique that can produce low resistivity metal films conformally over any feature accessible by process gas. In this work, we demonstrate successful Cu seed application by depositing a low-resistivity Ru metal film on Si trenches and through glass vias (TGV). Successful conformal ECD has been demonstrated with 10-20 nm of Ru in blind silicon vias with AR from 4:1 to 25:1 and in TGV with AR from 6:1 to 30:1. Further tests are ongoing to measure via resistivity after Cu ECD and to explore higher AR vias, such as 50:1.