Dielectric Coating Thermal Stabilization During GaAs-Based Laser Fabrication for Improved Device Yield
MIT Lincoln Laboratory Lexington United States
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The quality and yield of GaAs-based ridge waveguide devices fabricated at MIT Lincoln Laboratory were negatively impacted by the random lot-to-lot appearance of blisters in the front-side contact metal. The blisters signaled compromised adhesion between the front-side contact metal, underlying SiO2 dielectric coating, and semiconductor surface. A thermal-anneal procedure developed for the fabrication of GaAs slab coupled optical waveguide SCOW ridge waveguide devices stabilizes the SiO2 dielectric coating, by means of outgassing and stress reduction, significantly improving device yield. Stoneys equation was used to analyze stress-induced wafer bow in devices fabricated using this stabilization procedure. This analysis suggests that changes in wafer bow contribute to the incidence of metal blisters in SCOW devices.
- Lasers and Masers