Conformal Electroless Deposition of Barrier and Cu Seed Layers for Realizing All-Wet TSV Filling Process

Abstract

Conformal electroless deposition of barrier and seed layers was studied for fabrication of a high aspect ratio through-Si via (TSV). Formation of a thin barrier metal layer of Ni-B and Co-B is possible using a Au nanoparticle (Au-NP) catalyst, which is densely adsorbed on the SiO 2 of the TSV sidewall. A silane coupling agent of 3-aminopropyl-triethoxysilane is effective for enhancement of the adsorption density of Au-NP. A conformal electroless Cu layer is deposited on the barrier layer by displacement plating without a catalyst. These results strongly suggest that an all-wet process for the formation of Cu-filled TSV with a high aspect ratio is possible.

High aspect ratio through-silicon-via formation by using low-cost electroless-Ni as barrier and seed layers for 3D-LSI integration and packaging applications

“…Since the amount of P in the bath is quite small, hereafter we call the deposited film as EL-Ni. Although several reports available regarding TSV filling using EL-Ni film as either barrier layer (for HAR TSVs; 30) ) or as the TSV fill material (for AR < 7; 31,32) ), in most cases an additional seed layers were used to fill the HAR-TSV by Cu-electroplating. 30) Here we have attempted to use the EL-Ni layer as both barrier layer against Cu diffusion as well as the seed layer for successive TSV filling by Cu-electroplating.…”

“…Although several reports available regarding TSV filling using EL-Ni film as either barrier layer (for HAR TSVs; 30) ) or as the TSV fill material (for AR < 7; 31,32) ), in most cases an additional seed layers were used to fill the HAR-TSV by Cu-electroplating. 30) Here we have attempted to use the EL-Ni layer as both barrier layer against Cu diffusion as well as the seed layer for successive TSV filling by Cu-electroplating. EL-Ni plating was carried out for 5-8 min (depending upon the required Ni thickness) at the plating temperature of 60 °C.…”

“…One way to enhance the throughput for the deposition of BS layers is an electroless (EL) plating method. Previously for 3D-integration Ni-TSVs were fabricated by EL means, 29,30) but the AR is ⩽7. In contrast to PVD/ALD techniques, the advantages of the EL method are manifold.…”

Electroless Metallization of Dielectric Surfaces

“…Prior to plating, surfaces need to be catalytically activated to ensure conformal deposition of the metal (1). Gold nanoparticles can be used as the catalyst for this type of surface activation (1,5). However, palladium has shown to be a promising catalyst while boasting significantly reduced cost (4,(6)(7)(8)(9).…”