news113-19 February 2016

RTI-Research technology was presented to potential customers at SPIE Photonics West conference in San-Francisco.



Fusion of InP to GaAs wafers was first demonstrated at MIT in 1989. In the 1990s this process was applied for demonstration of double-fused 1550 nm and 1310 nm vertical cavity lasers with InP-based active region and AlGaAs/GaAs distributed Bragg reflectors (DRBs) at the University of California, Santa Barbara, and at the Swiss Federal Institute of Technology in Lausanne.

BeamExpress, a startup company founded in 2001, contributed further to the development of an industrial fabrication process of 1310 nm and 1550 nm wafer-fused vertical external cavity lasers (VCSELs) on two-inch wafers. To produce a fused wafer one should start with three initial epitaxial wafers: one InP-based active cavity wafer and two DBR wafers. Even though one 2-inch wafer can result in quite a large quantity of VCSELs (15,000 or even more depending of the chip size), reaching large production volumes on the order of millions lasers per year, as required by the photonic industry, is not really possible because epi foundries that produce initial InP-active and GaAlAs-DBR wafers, as well as foundries that perform VCSELs processing, no longer support 2-inch wafer processes.

As a solution to this problem, RTI-Research, another Swiss company, has started the production of 3-inch and 4-inch fused wafers for 1310 nm and 1550 nm vertical cavity lasers in a new, custom built wafer bonder. In this bonder all elements that are critical for 3-inch and 4-inch wafer fusion are optimized for reaching high fusion quality and yield.

Currently, RTI-Research is offering InP-to-GaAs wafer-fusion foundry services and looking for partnerships for fabrication of 1310 nm and 1550 nm vertical cavity lasers in large production volumes.

By increasing the fused wafer size from 2-inch to 4-inch, the total number of VCSEL chips with the size of 0.25 x 0.25 mm² from a wafer with 5 mm exclusion zone from edges increases from 20 k to 100 k.