Full-Wafer Technology—a New Approach To Large-Scale Laser Fabrication and Integration

Abstract

A new concept for full-wafer processing and testing for semiconductor laser fabrication in the AlGaAs-GaAs material system will be presented. the approach is based on chemically assisted ion beam etching for the laser-mirror formation. the technique routinely provides excellent mirror quality with mirror roughness of less than 200 A, resulting in mirror reflectivities of about 30% and scattering losses of less than 2%. Lasers with two etched mirrors have been fabricated that show equivalent output power/current (P/1) characteristics to lasers on the same wafer with both mirrors cleaved, up to more than 40 mW (CW) for uncoated mirrors. Single-mode operation exceeding 50 mW output power has been achieved for an SQW-GRINSCH ridge laser structure with coated, etched mirrors. Furthermore, the etching technique has been used to fabricate special devices and structures for on-wafer parametric laser and beam property characterization. This new approach to full-wafer testing allows efficient on-wafer functional testing of a large number of lasers on a 2-in wafer, with considerable improvement in testing throughput. the concept also incorporates many test sites for process characterization which provide important feedback for process improvement/optimization. in addition to the above advantages of full-wafer processing and testing, the availability of high-quality etched mirrors will provide the potential for lasers with specially shaped mirrors, and will open up new opportunities for opto-electronic integration. the approach described has been developed for lasers to be used in optical storage at wavelengths of 830 and 856 nm. How-ever, the basic concept can be applied to semiconductor laser fabrication in any other material system and wavelength range. the major difference will be the adaptation of the mirror-etching process to the composition of the material. © 1991 IEEE.