SBIR-STTR Award

On-site recovery of constituent materials from compound semiconductor waste streams presents an opportunity for reduction of hazardous material waste and cost of manufacturing. UDRI has developed a low-cost process for recovering gallium and arsenic from the production of gallium arsenide where the primary contaminant is the other element of the binary compound. This method can be applied to other compound semiconductors also. AXT proposes to grow gallium arsenide crystals from waste materials recovered by the UDRI process from AXT's normal gallium arsenide substrate manufacturing production line. The crystals will be wafered and analyzed by typical compound semiconductor analysis techniques such as Hall effect, GDMS, X-ray, etc. to determine what level of binary residual can be successfully used to grow high quality crystals. Additionally, preliminary studies will be made to determine the concentration of contaminants in the recovered gallium and arsenic and their impact on the purity of the grown crystals. Since the typical starting materials are 6-7N purity, the on-site recovered materials may retain similar purity after the UDRI process. Successful demonstration of crystal growth will pave the way for implementation of the recovery process in a commercial volume-production environment. Successful implementation of the on-site recovery technology can lead to reduction in waste and cost of compound semiconductor crystals. Localized waste recovery avoids the cost of landfill and future potential hazards.

Keywords:
III-V, On-Site, Recovery, Crystal Growth, Waste Reduction, Recycling, Cost Reduction, Semiconductor

Throughout the industrialized world there is a growing concern over the impact of industry on the environment, as well as concerns about losses of strategic materials. The III-V semiconductor manufacturing industry is no exception to theseconcerns. The production of gallium arsenide(GaAs), gallium phosphide (GaP) and indiumphosphide (InP) devices for military andcommercial uses (e.g., cellular phones and othercommunications equipment) results in a number ofwaste streams for which there are currently nobroadly acceptable recovery options. The III-Vcrystal growing foundries typically produceseveral waste streams of which only a few arepresently recycled. One such waste stream issolid dusts, cuttings and fragments from theprocessing of GaAS, GaP, or InP boules intowafers. This waste stream also includesout-of-spec wafers of GaAS, GaP, or InP, theslurry waste from slicing and polishing of wafers, and the large-volume aqueous of wastes frometching and polishing operations. These wastestreams are of concern because they may representa long term liability to the company. In Phase IAXT and UDRI have demonstrated the feasibility ofa low-cost purifacation process for III-Vcompounds which can be implemented in an on-siterefinery. In Phase II AXT proposes to demonstratecommercial feasibility of the process.

Keywords:
III-V; RECOVERY; WASTE REDUCTION; COST REDUCTION; ON-SITE; CRYSTAL GROWTH; RECYCLING; SEMI