Cavity Ring Down Spectroscopy (CRDS)

Cavity Ring Down Spectroscopy (CRDS)

By Kevin Nguyen, SEMI Standards­

The SEMI North America Facilities and Gases Committee recently met on April 2, 2013 in conjunction with the North America Spring Standards meetings in San Jose, California.   The committee approved a new Test Method for Determination of Moisture Dry-Down Characteristics of Surface-Mounted and Conventional Gas Delivery Systems by Cavity Ring Down Spectroscopy (CRDS).

CRDS test method describes the procedure for determination of the moisture dry-down characteristics (quantity of removable moisture) of surface mount (integrated gas delivery systems) and conventional gas delivery systems using CRDS analyzers.

The results of this test can be used for qualitative ranking or qualification of a gas delivery system based on the design. It can also be used for numerical simulation of a gas distribution system behavior.

Steven Rowley of Tiger Optics noted that CRDS analyzers provide the user with an absolute measurement (no calibration gases required) down to parts per trillion (ppt) level of detection limits. The equipment is simple to install and does not require a skilled technician to operate. The analyzers do not have any moving parts and the only “maintenance” required is a software routine. Furthermore, unlike Atmospheric Pressure Ionization Mass Spectrometry (APIMS) instrument, CRDS equipment is cheaper to conduct moisture dry-down test method.

This document is now being checked by the International Standards Committee Audit and Review Subcommittee to ensure that proper SEMI Regulations were followed.  Once approved, the document is expected to be published in June 2013 in the Facilities volume

If you have any questions about participation or would like to join our Filters and Purifiers task force, please contact Kevin Nguyen at For more information on Standards activities at SEMI or upcoming meetings, please visit:

SEMI, Standards Watch - May 2013