CIC Photonics

Detection and measurement of GWGs in semiconductor fab facilities


Courtesy of CIC Photonics

Problem Statement

Various processes and tools in the modern wafer fab plant produce effluent streams that contain unacceptably high levels of perfluorocarbon GWGs (greenhouse warming gases). These effluent streams are abated by plasma incineration and wet scrubbers and other techniques. It is necessary to measure the destruction removal efficiency (DRE) of the various abatement methods to ensure compliance with EPA standards.

IRGAS Applicability

The IRGAS PFC-LABTM is a dual solution analytical tool that is designed for complete analysis of all the constituents that are found in the process gas effluent stream that enters an abatement tool and the abated stream that exits the abatement unit. The IRGAS PFC-LAB incorporates CICP’s IRGASTM FTIR Gas Analyzer and either a Gas Chromatograph equipped with an AICC non-radioactive Helium Ionization Detector or a Quadrupole Mass Spectrometer. The long path gas cell employed in the FTIR system offers unparalleled optical power throughput and corrosive resistant surfaces. The gas chromatograph is a simple, low-cost unit with a unique detector design capable of measuring fixed gases in the field. The potent combination of the IRGAS Gas Analyzer and the AICC helium ionization detector equipped gas chromatograph ensure accurate and complete calculations of total DRE. The IRGAS system monitors all infrared absorbing gaseous species simultaneously by the use of a sophisticated chemometric analysis software engine, SPGASTM. The GC will sample the same gas stream to provide an accurate measure of all the gaseous species that are invisible to infrared radiation. The two analytical tools are complementary solutions to derive a complete analysis.

IRGAS System Description

The IRGAS PFC-LAB is built on a wheeled cart constructed from MiniTec aluminum extrusions. The cart includes a PC with flat screen monitor. This mobile lab cart allows safe and easy transport in and around the process facility. The system PC is used to operate both analytical tools and collect both data streams. The gas sampling system is available with heated lines and a heated gas cell to prevent condensation. The system analyzes complex, wet gas streams that are corrosive and toxic. The IRGAS PFC-LAB delivers extraordinary value by combining two analytical solutions on one platform with a single supervisory computer. The computer software is ready to communicate with higher level or peer systems by virtue of S.E.C.S. and Devicenet communications protocols.

Sample Data/Solution Achieved

Figure 1 shows the System Setup for a IRGAS-PFC-Lab containing a QMS combined with a FTIR. The spectral records in Figures 2 to 5 show gas species present in an abatement stream at three stages: during CVD deposition (pre-abatement tool); during abatement cleaning process, which shows abundant amounts of HF, SiF4, and NF3; and post abatement. The effectiveness of the tool is readily observable in Figure 5.

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