Industrial Productivity and Manufacturing
Technology
Cleanroom Contaminant Monitor
Helping to keep the work-setting free of airborne molecular contamination
is a task of Femtometrics, Inc. of Irvine, California. The company's Real-Time
Non-Volatile Residue (NVR) monitor was developed under a Small Business
Innovation Research (SBIR) contract for John F. Kennedy Space Center (KSC)
in Florida.
Femtometrics had responded to Kennedy Space Center's needs by proposing
an advanced, highly sensitive surface acoustic wave (SAW) microsensor capable
of detecting sub-monolayer deposition in cleanrooms where aerospace systems
are assembled.
Initial criteria established by KSC called for a technology that could
regulate the accumulation of nonvolatile residues in cleanroom environments.
The smallest speck of material can harm sensitive payloads being prepared
for launching. An ultra-clean work environment for assembly and final check-out
of a spacecraft is a must.
| Real-Time Nonvolatile Residue Monitor
developed by Femtometrics, Inc. is built to monitor for contaminants in
cleanrooms for spacecraft check-out but has found a new home in factories
of microelectronic chip makers. |
As specialists in trace analysis and instrumentation, Femtometrics had
responded years earlier to an SBIR solicitation by Langley Research Center.
Langley's interests centered on size distribution and mass concentration
of aerosols and chemical vapor in the stratosphere. NASA SBIR Phase I and
Phase II contracts were awarded to Femtometrics resulting in a highly sensitive
aerosol detector for environmental researchers.
Stimulated by the SBIR contract wins, the company set about developing
proprietary SAW resonator technology. A new type of sensor evolved from
the research.
The advanced sensor has the ability to measure a range of chemical vapors
by applying chemical-specific coatings on the sensing surface. The SAW
proved extremely sensitivet--two orders of magnitude greater than a competing,
NASA-developed instrument built to conduct the same environmental monitoring
function.
Femtometrics equipment can employ multi-SAW sensor array systems. These
offer a range of absorption characteristics. When exposed to a chemical-vapor
environment, the arrays produce a "fingerprint" of the specific
chemical vapor or vapors present. Coupled with custom-programmed adaptive
neural network software, the chemical compound fingerprint is analyzed
and identified.
| One use of Femtometrics, Inc.'s NVR-200
is in cleanrooms and in process control by semiconductor manufacturers. |
William Bowers, President of Femtometrics, explains that a prototype
Real-Time NVR monitor was used as an engineering tool during the ground
integration and launch processing of the Hubble Space Telescope replacement
optics and science instruments during its first servicing mission in 1993.
Hubble's second servicing visit by astronauts in 1997, Bowers adds, made
use of three passive sensor elements provided by Femtometrics which successfully
measured on-orbit contamination.
Commercial applications of the Real-Time NVR Monitor now include Class
1 cleanrooms at semiconductor and hard-disk manufacturing plants. Also,
the monitoring system is a process tool to measure condensable contaminates
in ultra-high purity operations that use gas and solvents.
Other federal organizations, such as the Department of Defense and the
Department of Energy, have found need for the SAW chemical-vapor detection
systems built by Femtometrics. Applications include scientific research
and chemical warfare detection.
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