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Product Briefing Outline: Picarro, a manufacturer of high performance lasers and laser-based instruments, has begun commercial shipments of its next generation ammonia measurement instrument. The instrument, the ESP-1000, is based on Picarro's patented Cavity Ring Down Spectroscopy (CRDS) and achieves better than 1 part-per billion detection of ammonia in ambient air, according to the company.

Problem: Ammonia exposure is a well-documented issue for advanced lithography where even part-per-billion levels can lead to wafer yield loss and unscheduled downtime of critical lithography equipment. Ammonia is emitted into the wafer fab by humans and various semiconductor manufacturing processes. Ammonia is difficult to measure at ppb levels because of its "stickiness" - its tendency to absorb to surfaces - such that varying temperature and ambient moisture levels can produce erroneous measurements. Few instruments exist that can simultaneously meet the sensitivity and speed requirements of the most demanding process control applications.

Solution: The ESP-1000 is designed to improve the detection limits and measurement speeds to enable real-time monitoring of airborne ammonia in critical lithography areas. The company claims that the device can achieve detection limits below 1 part-per-billion with a measurement time of a few minutes by directly sampling ambient air. These advantages are claimed to allow both lithographers and lithography equipment manufacturers to pinpoint and control ammonia risk areas before they impact production.

Applications: Picarro has applied its CRDS technology to make ultra-sensitive measurements of a variety of other gases including CO2 and isotopic CO2, H2O and isotopic H2O, and H2S as well as ammonia in lithography tools.

Platform: CRDS uses narrow-frequency, telecommunications-grade, tunable laser diodes with an ultra-high finesse optical cell to deliver unmatched spectral resolution
(0.0001 cm^-1) ~-1000 times better than an FTIR.  The high finesse optical cell results in an effective path length of ~40 km from a physical cell length of ~20 cm.  This enables high sensitivity to ultra-low concentrations of the target species.

Availability: March 2006 onwards.