At the recent IMAPS Device Packaging Conference in Scottsdale AZ Asahi Glass (AGC) and nMode Solutions of Tucson AZ announced that they had invested $2.1 million to co-found Triton Micro Technologies to develop glass based 2.5D Interposers. iMicronews thought this was worth A Closer Look.

The new company is headquartered in Tucson AZ with a manufacturing facility planned in CA. 
Triton Micro Technologies will manufacture glass interposers using AGC’s proven carrier-glass technology and via-hole drilling methodologies. Triton then will apply its proprietary technology to fill the high-aspect-ratio via holes with a copper paste that has the same coefficient of thermal expansion as glass. Triton CTO Steve Annas indicated that they are ready for prototyping now.
Mark Takahashi of AGC indicates that “..the production equipment will be in place by May when commercial production will commence in CA”. Takahashi added  that their roadmap shows a goal of 10 um holes in 100 um thick glass, the current industry accepted standard for silicon, in the future.
Their reported process flow is shown below:

Triton glass interposer design flow

AGC uses Alkali-free Boro-Aluminosilicate Glass,  EN-A1, which has low CTE and thermal expansion properties matched to silicon in order to reduce stress when wafer bumping the die to the interposer.  AGC‘s EN-A1 reportedly has refractive properties which allow for a low taper when laser drilled, providing for precise pitch control and hole size.

CTE vs Temperature for EN-A1 and Silicon

EN-A1 has a highly polished surface and can readily accept either thin-film or thick-film metallization directly on the glass without the need for an adhesion layer. Copper and Silver thick-film have been tested on EN-A1 with excellent results. Surface roughness of 10 Å or less is typical.

EA-N1 wafer properties are shown in the table below:

Typical EN-A1 wafer properties

Typical design specifications are shown in the table below:

 Typical design specs for EN-A1 interposers