With the ever increasing demand for miniaturization in microfabrication, three dimensional integration is considered the key for progress and reliable vertical interconnect accesses (vias) are crucial. Glass substrates are potent alternatives for silicon in 3-D technologies with their comparable characteristics, their advantage of inherent isolation, and low insertion losses. Through-Glass Vias (TGVs) are commonly metallized using PVD, CVD, or electroless deposition for a seed layer followed by the electrodeposition of copper. Inspired by molded interconnect devices (MID) technologies, the goal of this paper is a solely electroless TGV filling on the basis of three priming approaches: self-assembling monolayers of (3-mercap-topropyl) trimethoxysilane (MPTMS), a photocatalytic layer of titanium tetraisopropoxide (TTiP) and a sol-gel process. Priming with a TBuT solution proved to be particularly suitable. This coating has high-temperature resistance, good adhesion in the TGVs, and allows a solely electroless filling with a layer stack of NiCuNiAu and CuNiAu.

Approaches for a Solely Electroless Metallization of Through-Glass Vias

Electroless plating of a 5G copper antenna on polyimide patterned with laser-induced selective activation and curing of metal-organic catalyst

Electro-polymerization rates of diazonium salts are dependent on the crystal orientation of the surface.

http://sioc-journal.cn/Jwk_hxxb/EN/article/downloadArticleFile.do?attachType=PDF&id=349481

Research Progress of Electroless Plating Technology in Chip Manufacturing

Annealing process is generally adopted to reduce the residual stress and stabilize the microstructure of TSV-Cu in IC manufacturing. In this paper, the effects of capped Cu layer on the protrusion behaviors of TSV-Cu are investigated considering various double annealing processes. Higher protrusions of TSV-Cu with capped Cu layer are observed compared with that of TSV-Cu without capped Cu layer. The reason is that capped Cu layer impedes the elimination of grain boundaries and local misorientation during the first annealing, resulting in the remaining of larger amounts of atoms and higher energy in the grain boundaries. Thus, it is easier to induce protrusion by grain boundary migration during the second annealing. In addition, the capped Cu layer effects on mechanical properties of TSV-Cu under various double annealing conditions are investigated by nanoindentation test. The values of elastic modulus and hardness are generally higher in the presence of capped Cu layer. The reason is also discussed and clarified. 

Effect of Capped Cu Layer on Protrusion Behaviors of Through Silicon via Copper (TSV-Cu) Under Double Annealing Conditions: Comparative Study

Covalently formation of insulation and barrier layers in high aspect ratio TSVs

Chemical metallization of ultrathin polymer insulation film for through-silicon via application

With the development of miniaturization of electronic devices, the demand for through-silicon via (TSV) technology has become increasingly urgent. Insulation technology with function of preventing copper diffusion is a key issue for TSV quality and reliability. In this paper, a one-step selective grafting method was reported for covalently grafting polyacrylic acid (PAA) insulation films only on silicon (Si) surface without grafting on aluminum (Al) surface. This method is implemented in an acidic aqueous solution with 4-nitrobenzene diazonium tetrafluoroborate (NBD), hydrofluoric acid (HF), sodium tripolyphosphate (STPP) and acrylic acid (AA) monomers. The existence of STPP in the solution can not only make Si more susceptible to corrosion and further facilitate grafting reaction of PAA films on Si substrate, but also form a layer of sodium fluoroaluminate precipitated film on the Al surface and further avoid the grafting reaction caused by NBD and corrosion of Al by HF. In addition, the effect of surfactants on PAA film formation was studied. Experiments shows that the combination of Sodium dodecyl sulfate (SDS) and sodium lauryl sulfate (SLS) as surfactant can obtain PAA films with great compactness and uniform thickness. This one-step selective grafting method on Si and Al surfaces will have great application prospects for CMOS image sensors (CIS) package when the aspect ratio of TSV increases.

Yaofang Hu

Papers

Covalently formation of insulation and barrier layers in high aspect ratio TSVs

Chemical metallization of ultrathin polymer insulation film for through-silicon via application

A Selective Grafting Method of Polyacrylic Acid Insulation Films on Silicon and Aluminum Surfaces for TSV-CIS Package