Alchimer to launch AquiVia process for TSVs midyear

AquiVia eliminates dry process techniques from TSV metallization.

By Gail Flower, Contributing Editor -- Electronic News, 2/6/2009

At SEMICON West 2009, Massy, France-based Alchimer SA will launch its third product: AquiVia, a process used for wet deposition of the insulation and barrier layers inside high-aspect ratio through-silicon vias (TSVs). AquiVia eliminates dry process techniques from TSV metallization, according to the start-up company.

Using AquiVia, conformal, uniform insulation and barrier layers can be produced inside a TSV with aspect ratios at 10:1, even on the highly scalloped TSV etch profiles produced by the DRIE/Bosch process, the company said. Combined with Alchimer's eG ViaCoat product, which creates conformal copper seed layers, the same tool can be used for the deposition of insulation, barrier, and seed layers.

“This latest breakthrough is predicted to eliminate all dry processing techniques from TSV metallization, cutting the cost of ownership of the via stack metallization by more than 70%,” said Steve Lerner, president and CEO.

AquiVia technology, used with eG ViaCoat, provides conformal and uniform insulation, barrier and seed layers using Alchimer's electrografting technology, in which conformal coatings can be grown on the surface of conducting and semiconducting materials by applying a solution containing specific chemical precursors and an external current source. The barrier layer is produced using Alchimer's chemical grafting process, whereby electrons are derived from reactants in the solution rather than from an external current source.

“Dry processes, including PVD and CVD, cannot cope economically with the demands of high-aspect ratio TSVs for 3-D IC packaging,” said Lerner. “The limitations of these processes are major roadblocks to the advancement of the semiconductor industry.”

There will be many versions of TSVs: via first, middle, or last. AquiVia will end up being a family of products, each suited to the particular method used. “One application won’t fit all,” said Lerner. “Our isolation is a polymer and we can tune it to the various design rules and TSV applications as opposed to today’s defacto standard using SiO2.”

The first product introduce by Alchimer, eGSeed, is an electro-grafted Cu seed layer technology that makes it possible to create reliable interconnects at 45-nm node and beyond. Alchimer claims more than 90% Cu seed step coverage and precise thickness control from 5 to 30 nm. Resistivity is 10µOhm.cm at 10nm.

The next product Alchimer introduced, eG ViaCoat, allows the metallization of TSVs used in advanced 3-D packaging applications. For vias from 3 to 150 µm in diameter, continuous Cu seed layers from 50 to 200 nm can be created, with typical resistivity of 1.8 µOhm.cm at 200 nm.

The eG ViaCoat won the Best of the West Award at SEMICON West 2008 as chosen by journalists, academicians, and industry leaders basing their choice on engineering or scientific achievement, financial impact and/or societal contribution. There were 1200 entrants representing 23 countries. eG ViaCoat was also a finalist in the Advanced Packaging and Eurasia IC Industry awards. In October 2008, NEXX Systems licensed it for 3-D applications; and in December DALSA Semiconductor licensed it for MEMS processes with Cu TSVs.