The SENTRY TCM’s analytical platform is based on Metara’s
patented Inline Mass Spectrometry (ILMS) technology. Metara’s
metrology tools are fully automated to include sample collection, sample
preparation, spectral analysis and quantitation of results. Analysis
results are available in minutes. Sampling errors due to manual sample
collection and handling are eliminated. The SENTRY TCM can be operated
in either metrology or diagnostic modes. Diagnostic mode can be used
for process characterization, debug and failure analysis, or “copy
exactly” measurement.
ILMS enables the use of state-of-the-art mass spectrometry methods in
reliable metrology applications. Automated sampling of process baths
can occur at distances of greater than 30 meters, and each sample is automatically
spiked with an internal standard. These standards are either stable
isotopes of the contaminant to be measured or have similar compositions. These
internal standards provide accurate quantitative measurement, compensating
for matrix effects and instrument drift.
ILMS also enables the use of high-resolution electrospray ionization time-of-flight
mass spectrometry (ESI-TOF MS) techniques. A hexapole ion guide
is used in the mass spectrometer as a 2D ion-trap—allowing for the
accumulation of low-count ion populations for improved sensitivity. By
reversing polarities at certain points within the mass spectrometer, positive
or negative ions will be generated and analyzed, enabling both cation and
anion analysis under automated computer control.
The high resolution of the TOF MS analyzer (0.02 to 0.05 amu vs. 1 amu for
quadrupole MS) enables the separation of organic from metallic peaks and
accurate molecular fragment identification.
