January 15, 2010 – Allvia says it has completed integration and full reliability testing of a silicon interposer between a semiconductor die and an organic or ceramic substrate.

The company says it has solved the problem involved with 3D stacking of various compositions of substrate materials with different coefficients of thermal expansion, by putting the Si interposer between two stacked substrates and connecting them with through-silicon vias (TSV).

Using Si interposers also eliminates the need to requalify die with feature-size shrinks and changing pitch; and it avoids costs incurred from having to use more expensive substrates. (The company’s TSV work with flip-chips on the backside enables it to make cost-effective silicon interposers, added Sergey Savastiouk, CEO of Allvia, in a statement.) There are no material mismatches in such "hybrid substrates" with silicon on top and organic substrate beneath, as long as device reliability is confirmed, the company noted.

"There is a big difference between what we are demonstrating and multi-chip modules because we can build passive elements right onto the silicon substrate," noted Savastiouk.