We don’t need to tell you the importance of ensuring the purity of specialty gases – whether they are ultra-high purity single gases or complex gas mixtures used in semiconductor manufacture, says instrumentation specialist Process Sensing Technologies (PST).
Although gas purities vary, typically the purity required is between 99.998% and 99.99994%, the company continues to explain. The most common contaminants for users to manage are moisture and oxygen, however, a whole range of other trace gases and complex hydrocarbon impurities also need to be controlled down to low parts-per -billion (ppb) and require specialist analysers to monitor these gas streams.
Just to add to this already intricate picture, semiconductor manufacture may use up to 30 different gases in various processes. These include gases such as helium, nitrogen and argon which are used either to provide an inert atmosphere or to flush chambers at the end of a process or before cleaning. Other gases are used in carefully controlled amounts to ensure that reactions do take place.
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