Figure 1: Electrografting provides a very strong adhesion between organics and any surface

Streamlined and versatile: that’s the impression I came away with after talking to Nao Shoda, senior director of business development and technology, Alchimer, about recent developments to further optimize the companies’ electrografting processes for through silicon via (TSV), isolation, barrier, seed and fill steps. I wrote about them frequently in the company’s early days, and again since the company resurfaced in January, touting a new business model and application focus. The company also demonstrated at that time that they had successfully combined the seed and fill steps into a single process.

eG3D-Polymer

SEM of eG3D Polymer coverage.

But there’s still more to tell, as the company announced a new collaboration with Leti to evaluate its wet metallization processes for high aspect ratio TSVs at SEMICON West, and also shared some information on its newest addition to the eG3D product family, features of eG3D Polymer, which they first hinted at IMAPS DPC back in March.

Shoda explained that the purpose of this product is to further reduce cost of metallization processes by combining the insulator and barrier steps, eliminating Cu diffusion barrier step in this instance. It offers advantage in the way the redistribution layer (RDL) step is done. One of the issues with via reveal after traditional RDL, is the potential for copper contamination of silicon oxide that creates a micro-electric defect. By using eG3D Polymer instead of silicon oxide for RDL, the barrier properties prevent contamination of the insulator.

For interposer TSVs, eG3D Polymer is also an ideal solution, and further reduces the manufacturing cost. If this two-step process is implemented, Alchimer’s eG3D Polymer acts as dielectric isolation and diffusion barrier and following eG3D Fill uses chemical grafting.

Shoda was careful to point out that eG3D Polymer was not developed to replace the 3 step process altogether, and that in the case of high aspect ratio (HAR) TSVs, the company recommends its eG3D isolation, barrier and fill steps. The point is, the company has identified where it pays to streamline processes, while also being versatile enough to suit a variety of TSV applications. ~ F.v.T.

Francoise von Trapp

They call me the “Queen of 3D” because I have been following the course of…

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