Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Patent
1995-11-20
1997-12-30
Fields, Carolyn E.
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
2503391, 250345, G01N 2135, G01N 2139
Patent
active
057033650
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for analyzing trace amounts of a component which is included in a gas to be measured by means of infrared spectroscopic analysis employing a diode laser as the light source, and to a device which employs the method therein.
BACKGROUND ART
Infrared spectroscopic analysis is frequently used as a method for analyzing a gaseous test material. A simple explanation will now be made of the principle of infrared spectroscopic analysis. In polyatomic molecules, each molecule has its own vibration energy level corresponding to the bonds between the atoms which make up the molecules. For this reason, when the molecules are exposed to electromagnetic waves of a wavelength which has a photon energy equivalent to the value of their vibration energy level, the molecules absorb the electromagnetic waves as their own vibration energy. The amount of absorption, moreover, is proportionate to the abundance of the molecules present. When this vibration energy level value is converted to photon energy, ordinarily, it will correspond to wavelengths in the infrared region.
Accordingly, in infrared spectroscopic analysis, light in the infrared region is passed through the gas to be measured and the absorption spectrum is measured. Analysis is carried out by analyzing the absorption spectrum. Identification within the gas to be measured of gaseous molecules (impurity) targeted for measurement here can be made from the wavelength of the light absorbed. A quantitative determination of those molecules can then be made from the absorbance.
For example, in the semiconductor industry, various types of gases are used as the material for semiconductors. In Very-Large-Scale-Integration manufacturing processes, impurities such as moisture, for example, are damaging if present in even extremely trace amounts in the semiconductor material gases. Accordingly, reducing and controlling impurities in the semiconductor material gas is an important aspect of production control.
The present applicants previously submitted a patent application (Japanese Patent Application, Laid-Open No. Hei 5-99845) for an invention relating to a method for measuring the moisture in a gas using a tunable InGaAsP diode laser which oscillates in the region of wavelength 1.3 to 1.55 .mu.m.
The device for analysis of the moisture recorded in this publication is provided with a diode laser which oscillates in the region of wavelength from 1.3 to 1.55 .mu.m at room temperature; a measurement line which causes the laser light oscillated at room temperature from the diode laser to branch, guides it into a gas cell used for measurement, and then sends it on to a light detector for measurement use; a reference line which causes the aforementioned laser light to branch, guides it into a gas cell used for reference, and then sends it on to a light detector for reference use; and a power monitor line which causes the aforementioned laser light to branch and sends it on to a light detector which is used as a power monitor. The device is designed to employ as the aforementioned detectors, light detectors which are sensitive to light in the region of wavelength from 1.3 to 1.55 .mu.m at room temperature.
In the method for measuring moisture using this device, the laser oscillating wavelength is scanned by means of varying the injection current to the diode laser, and the absorption spectrum is measured. For example, the absorption peak for H.sub.2 O which is in the region of wavelength of 1.38 .mu.m is selected, and the water vapor concentration in the gas is measured using the absorption intensity and a calibration curve made in advance. The application of this method, which permits easy in-situ measurement and is useful as a process monitor in the production control process, was anticipated for analysis of semiconductor material gases.
Examples of the absorption spectrum disclosed in the above publications are shown in FIGS. 22 and 23. FIG. 22 is an absorption spectrum for the case where the gas component is H.sub.2 O on
REFERENCES:
patent: 5445964 (1995-08-01), Lee et al.
patent: 5508525 (1996-04-01), Day et al.
Ishihara Yoshio
Masusaki Hiroshi
Matsumoto Koh
Wu Shang-Qian
Fields Carolyn E.
Nippon Sanso Corporation
LandOfFree
Infrared spectroscopic analysis method for gases and device empl does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Infrared spectroscopic analysis method for gases and device empl, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Infrared spectroscopic analysis method for gases and device empl will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-204854