This specification was technically approved by the Global Gases Committee and is the direct responsibility of the North American Gases Committee. Current edition approved by the North American Regional Standards Committee on August 29, 2002. Initially available at www.semi.org September 2002; to be published November 2002. Originally published in 1983, previously published in 1994.

Recognizing the importance of impurity content of gases in the manufacture of semiconductors, suppliers responded by introducing products with improved analytical characterization, notably for trace impurities. Products which meet all of the requirements may be described as "meeting SEMI specifications." Where an analytical procedure different from that provided is substituted by a supplier or user, the burden of proof is on said supplier or user to confirm the equivalency. It should be noted that the following list of criteria was considered when determining the specified analytical method: Reliability; Ease of Use; Maintenance; Precision; Accuracy; Sensitivity; Versatility; and Availability of Equipment.

This specification is specific to Ammonia (NH3) in Cylinders, 99.998% Quality - used in the manufacture and processing of semiconductors and advanced electronic devices and circuits. A gas conforming to the specifications will commonly contain more of the major component than the minimum permissible limit or contain less of an impurity (or several impurities) than the SEMI C3 maximum permissible limit. In neither case shall the gas be considered as of higher quality than that defined by the specification.

The intent of these specifications and the associated procedures is, on one hand, to assure that a gas is suitable for the common uses to which it may be put in the manufacture and processing of semiconductor devices and, on the other hand, to be consistent with contemporary manufacturing processes for that gas.

Referenced SEMI Standards
None.

Revision History
SEMI C3.12-1102 (technical revision)
SEMI C3.12-94 (technical revision)
SEMI C3.12-89 (technical revision)
SEMI C3.12-83 (first published)