Date: Nov 05, 1999 Source: MDA (
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Summary:
Los Gatos Research (LGR; Mountain View, CA) developed a visible and near-infrared absorption spectrometer that offers very high detection sensitivity. By using small, continuous-wave indium gallium arsenide lasers and a Cavity Ringdown Detection (CRD) geometry, LGR's device will offer continuous frequency scanning and detection sensitivities for water vapor of less than 1 part-per-billion—levels considered to be 10 to 100 times more sensitive than current detection methods. This sensitivity level is needed by the semiconductor industry to detect trace concentrations of water in highly reactive gases used in VLSI manufacturing. LGR is developing a trace-level water vapor detection system that will be marketed to the suppliers of gases used in semiconductor manufacturing.
Technology Description:
Los Gatos Research has developed a visible and near-infrared absorption spectrometer that offers very high detection sensitivities. This device is designed to be used as a microcontamination and water impurity sensor for semiconductor manufacturing applications. By using small, continuous-wave indium gallium arsenide (InGaAs) lasers and a Cavity Ringdown Detection (CRD) geometry, LGR's device will offer continuous frequency scanning and detection sensitivities for water vapor of less than 1 part-per-billion—levels considered to be 10 to 100 times more sensitive than current detection methods.
The CRD geometry is an effective method of increasing the optical path length for sensors. An axial cell is used with mirrors at both ends to confine and internally reflect the light from the InGaAs lasers. One of the mirrors has a detector that can measure the transmission loss through the mirror. If the amount of transmitted light is less than that expected from an empty cell, absorption of the light is occurring within the cell, and the frequencies absorbed are indicative of the absorbing species. By reflecting the laser back and forth within the cell, the effective path length is increased to as much as 10 kilometers, and the path length is directly proportional to detection sensitivity. LGR's new scheme provides this increase in species detection limits while not greatly increasing the complexity and power consumption of the instrument.
MDA Origins:
LGR, in conjunction with SRI International, developed the trace-level water vapor sensor under a 1997 BMDO STTR Phase II contract. The device could help BMDO to achieve the ultimate process purity for very large scale integration (VLSI) semiconductor manufacturing.
Spinoff Applications:
One of the most important factors in determining the process yield of semiconductor chips is the purity of the materials used in the growth deposition stages. One source of impurities arises when chlorine gas is contaminated with trace amounts of water. When this occurs, the resulting hydrochloric acid can etch small amounts of metal from the gas storage containers and carry this contaminant down stream to the deposition/etch chamber. Currently, diagnostics are used to limit such water contamination to sub-part-per-million.
LGR's water vapor sensor provides new diagnostics to a part-per-billion sensitivity. This capability would be particularly attractive to the semiconductor industry, which needs to detect trace concentrations of water in highly reactive gases used in VLSI manufacturing. Such high detection sensitivity could help increase the yield of integrated circuit chips produced.
Commercialization:
LGR is developing a trace-level water vapor detection system that will be marketed to the suppliers of gases used in semiconductor manufacturing. The system, which will cost about $40,000, can be connected to the gas lines outside of the vacuum chamber. In this position, it can detect contamination both in the lines or in the storage containers before the gas enters the chamber. The system is compact in size, measuring less than a cubic foot. In addition, LGR is working with the U.S. Army's Night Vision Laboratory to develop a water detection system for a chemical vapor deposition system used to make advanced gallium arsenide wafers.
Company Profile:
Incorporated in 1994, LGR is actively engaged in the development and sale of new chemical and physical sensor systems for both Federal government and industrial applications. Typical applications for these systems include the quantitative measurement of trace quantities of various chemicals in gasses or liquids, 2-D imaging of materials for non-destructive testing, and measurement of physical parameters such as temperature or pressure via non-contact remote methods. Currently, LGR has 5 employees.
