GC-MS
Gas Chromatography-Mass Spectrometer
Gas Chromatography-Mass Spectrometer is complex system that combines Gas chromatograph (GC) and Mass spectrograph (MS). It
is used for quantitative and qualitative analysis of organic compound.
The system can handle with microcomponent analysis and simultaneous analysis. When liquid or gas-state specimen is first injected
into vaporizing chamber, liquid specimen is heated for gasification so as to flow into separation column, while gas-state
specimen directly flows into the column.
Separation column is a tube with diameter of 0.5mm or less and length of few10m, generally having liquid layer inner wall.
Compound is separated into individual element after passing through the column.
The column then exhausts the element which is to be ionized; e.g. crushing accelerated electron against element (electronic
ionization). The act of higher internal energy induces molecule cleavage reaction to produce fragment ion. Since this cleavage
is a reaction that takes place in a way specific to structure of constituent, qualitative analysis is realized through mass
spectrum investigation.
Example
Organic compound analysis (clean room environment)
Sampling
Catch ambient gas with gas tube (160mm in length) and mini pump.
Measurement
Analyze organic compound caught in gas tube, by means of GC/MS
GC/MS(QP-5000, Shimazu)
Result
Total Ion Chromatogram of clean room environment
(0.1 litre/min, catch for 100min)
Each peak line represents individual organic compound. From the graph, many organic compounds are detected, and total amount
of organic substance was measured 362µg/m³.
Among compounds detected, toxic organic silicon compound- cyclic siloxane D3 (200ng/ m³) and D5 (410ng/m³) are detected, but
the contents were proved to be short for inducing defect in silicon nitride film.
Quantitative / Qualitative analysis of Organic compound adsorbed on wafer
Silicon/ quartz/ metal film (wafer with size up to 8 inches) are measurable.
Sampling
Heat wafer to 400 degC in wafer heating oven, and catch outgas by means of Tenax tube. After catching, segregate adsorbed
material at 250 degC to inject into GC-MS, which then measure the input material.
(From catching to injection into GC-MS is processed in-line)
Wafer heating oven SWA-256 (GL science),
QP-5050A (Shimazu)
Result
Upper graph shows total ion chromatogram before storage in wafer case,
Lower graph shows total ion chromatogram after 30-days storage in wafer case.
After 30 days of storage, many organic compounds such as phthalate ester are adsorbed, suggesting control on storage method
being necessary.