SEMI F77 - Test Method for Electrochemical Critical Pitting Temperature Testing of Stainless Steel Surfaces Used in Corrosive Gas Systems
This Standard was technically approved by the Gases Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on May 19, 2015. Available at www.semiviews.org and www.semi.org in September 2015; originally published July 2003; previously published March 2010.
NOTICE: This Document was completely rewritten in 2015.
The purpose of this Test Method is to determine the relative resistance to pitting corrosion of the wetted surfaces of components intended for use in corrosive gas distribution systems for semiconductor manufacturing. This Test Method is an adaptation of ASTM G150 and is intended to differentiate between alloy compositions or processes that may affect the corrosion performance of the wetted surfaces.
Detailed information on the method is found in ASTM G150, and it is recommended that the user have a copy of ASTM G150 for application of this Test Method.
This Test Method describes a procedure, based on the electrochemical critical pitting temperature (CPT), which is used to rank the pitting corrosion resistance of wetted surfaces of tubing or test coupons of representative finished surfaces intended for use in corrosive gas systems. Pitting corrosion is believed to be a major corrosion failure mode in semiconductor gas delivery systems, particularly in components and tubing welded and exposed to corrosive gases and moisture.
This Test Method is an adaptation of ASTM G150. The adaptation describes a method for performing the test method on coupons or wetted surface sections cut from gas supply system components such as tubing. It is an aqueous immersion method.
This Test Method is reproducible and provides a metric (CPT) in addition to a qualitative (visual) evaluation of corrosion resistance.
Referenced SEMI Standards
SEMI F19 — Specification for the Surface Condition of the Wetted Surfaces of Stainless Steel Components