All-Solution-Processed Metallization of High Aspect Ratio Through Glass Vias (HAR-TGVs) with a High Adhesion Promoting Layer (APL)

Metallization of through glass vias (TGV) by wet processing has received a lot of attention in recent years. However, there are two critical challenges - (i) the adhesion of the interface between the glass and the copper film is usually poor, (ii) void-free or seam-free filling of HAR-TGVs is challenging¹. In this study we developed a solution-based metal-oxide layer as the adhesion promoting layer (APL) which can be applied by various traditional coating approaches (Ex: spray coating, dip-coating and so on). The adhesion is around 6.5 N/cm, which is close to the commercial requirements^2-3. Adhesion is tested by using a 90-degree T-peel test. In the current work, our APL was deposited on the sidewall of the HAR-TGV using a ~109 nm-thick dip coat, as shown in Figure 1. We successfully demonstrate an all-solution-processed metallization and defect-free filling with APL for HAR-TGVs fabrication. The void-free HAR-TGVs filling can be achieved by using single-additive Cu filling formulation⁴ under stagnant conditions, as shown in Figure 2. It is worth noting that the Cu bridge (butterfly pattern) can be formed under direct current (DC) and stagnant conditions unlike the complex periodic pulse reverse (PPR) plate waveform that is used in a complicated strong flow field environment, thereby offering a simple processing option.