InP to GaAs wafer fusion was first demonstrated at MIT in 1989. Later-on in the 90-s this process was used to for the development of 1550 nm vertical cavity lasers with InP-based active region fused to top and bottom AlGaAs/GaAs distributed Bragg reflectors, DRBs at the University of California at Santa-Barbara (UCSB), USA and Ecole Federale Polytechnique de Lausanne (EPFL), Switzerland.
A start-up company BeamExpress, founed in 2001, further developed this technology for production of 1550 nm and 1310 nm VCSELs on 2-inch wafers. Because 1550 nm and 1310 nm VCSELs main advantage as potentially very low cost communication lasers for long-reach single mode fiber links can be realized only in very large production volumes, a 2-inch wafer fabrication process is not suitable any more for the fabrication of tens of millions of such lasers per year as requested by the industry. In addition, most of InP and GaAs epitaxial growth and processing foundries do not support 2-inch wafer fabrication any more.
As a solution to this bottle-neck RTI-Research is developing 3-inch and 4-inch wafer fusion process. The fusion process is performed in a custom built wafer bonder with considerably improved characteristics compared with previous bonders that were used for the 2-inch wafer fusion process. In the construction of the new equipment all elements that are critical for the realization of high-quality 3-inch and 4-inch fusion. With this new evolution of wafer fusion technology of InP-based and GaAs-based device structures RTI-Research makes its contribution to new generations of low cost and low power consumption communication lasers that are required by the photonics industry.