Based upon Tiger’s performance, the SEMI F-112 standard calls out CRDS as the technology of choice in determining moisture dry-down characteristics of high-purity gas systems. To check incoming or point-of-use quality, Tiger’s CRDS analyzers monitor for O2, H2O, CH4, CO, CO2 and more down to parts-per-billion (ppb) and even parts-per-trillion (ppt) levels. A special low-pressure version, the HALO LP monitors for impurities in hydrides, including arsine, phosphine and ammonia. If low-ppb moisture measurement in pure ammonia is required, the ALOHA+ H2O specializes in this application.
The high potential for atmospheric leaks during cylinder and truck fill, as well as in gas delivery, storage and distribution systems, drives the requirement for continuous on-site production monitoring at the world’s leading semiconductor fabs. Typically, H2, N2, Ar, He and O2 are monitored for trace H2O, O2 and CH4 contamination. Other contaminants that may be monitored are CO, CO2, and acid gases.
The recent addition of air and CDA to the measurement list addresses the latest Lithography requirements. For qualifying new gas lines and welds, dry Ar and N2 are typically used. To ensure gas quality throughout the fab, monitoring is also performed at gas cylinders, in addition to the lines following a cylinder exchange and at purifiers to verify their functionality.
The Compressed Gas Association Standard, CGA G-10.1, Commodity Specification for Nitrogen, now cites Cavity Ring-Down Spectroscopy as an approved method for moisture measurement.
CGA standards have been adopted by governmental agencies in the United States and Canada.
Based on a unanimous decision by the members of the Atmospheric Gases and Equipment Committee in August 2016, this change is welcome news to our many users in the industrial gas community. Specializing in CRDS since 2001, Tiger Optics offers a proven range of moisture analyzers for nitrogen.