Stable vapor transportation of solid sources in MOVPE of III–V compound semiconductors

Abstract

Trimethylindium (TMI), in spite of being a solid, has remained the precursor of choice for the deposition of indium containing layers by MOVPE. However, maintaining stable TMI flows and constant concentrations in gas phase during the growth still continue to be a major concern in MOVPE. This issue is further compounded by lower TMI consumptions achieved as the MOVPE growth conditions become increasingly more aggressive to meet the industry demand of higher throughputs, e.g. at higher flow rates, or at reduced pressures or when TMI source is maintained at higher temperatures. In this paper, we report our new findings of improved TMI delivery (>90, and in some cases >95%) with excellent stability of TMI concentration throughout the cylinder lifetime. These results are achieved using standard fill capacity and under intentionally set aggressive conditions of pressure, temperature and flow. We report a novel delivery technology (Uni-Flo™ II cylinder) that is customer proven and comprises innovative improvements to our dip-tube-less cylinder design, Uni-Flo™ cylinder, and advancements in TMI packaging. In this report, TMI depletion rates are examined over an extensive range of operating parameters currently employed in MOVPE, viz. flow rates ranging from 100 to 1000 sccm, source temperatures between 17 and 30 °C, and reactor pressures in the range 300–1000 mbar. We report, significant improvements in TMI delivery (>95% depletion) at higher molar flux of TMI (>3 g/h) and an excellent reproducible dosimetry of TMI with no batch-to-batch variation, by using Uni-Flo™ II cylinder as the enabling solution to TMI delivery problems.