High-Temperature Corrosion of AISI 316L in Chlorosilane Environments at 550°C

Chlorosilanes (Cl-Si-H compounds) are ubiquitous in modern silicon refining and semiconductor device manufacturing technologies, which are often operated at temperatures above 500°C. Corrosion of metals-based process hardware (e.g., reactors, tanks, and piping) in these environments can compromise manufacturing productivity and hardware durability.  In this study, AISI 316L was subjected to various high-temperature (550°C) chlorosilane environments for up to 100 hours.  Hydrogen gas ((H₂) saturated with  silicon tetrachloride (SiCl₄) (STC)) was combined with clean hydrogen (H₂) and anhydrous hydrogen chloride (HCl) in ratios relevant to manufacturing process streams.  The presence of both STC and HCl during these exposures leads to the formation of metal chlorides and silicides on the surfaces of AISI 316L.  While the metal silicides were stable and formed a protective surface layer, the metal chlorides were volatile and formed non-protective surface layers.  Surface and mass analyses before and after 100 hour exposures showed predominately surface chlorination (and sample mass loss) with  HCl/STC mole ratios (feed stream) >~0.18.  With no HCl in the feed stream, surface silicidation was predominate, and the samples gained mass.  Experimental methods, data (316L) and interpretations will be presented and discussed in the context of advancing understanding of high-temperature corrosion (and protection) of metals in chlorosilane environments.