Fab Ambient Monitoring
CRDS Ambient Monitoring in Semiconductor Fabs
As logic and memory devices are pushed to higher densities and more complex architectures, maintaining target yields creates an increasing need to eliminate certain trace gases from the ambient air in the front-end fab environment. These include NH3, H2S, HCl and HF. Low levels of ammonia and other amines are present in ambient air in a semicon fab, naturally produced by human operators and sometimes from wet chemistry processes. Ammonia can cause quality and yield problems such as T topping, and it can also cause photochemical damage to optical surfaces. H2S, HCl and HF are other problem gases that can be released into the ambient air during lithography and related processes.
Commercial scrubbers and flow hood technologies are very efficient at removing all these gases but their potential impact means that the filtered air must then be verified and monitored by trace gas analysis instruments. In fact, some equipment manufacturers even require periodic audits of amine levels in the lithography area to maintain warranty status. Picarro CRDS analyzers are used in these applications because they provide the highest sensitivity of any portable trace gas analyzer, they can be configured to detect several different target gases with no crosstalk, and they can operate for months without the need for recalibration.
