Gas concentration measurement apparatus

Abstract

In order to provide a gas concentration measurement apparatus that suppresses any change in the temperature of an optical fiber, and also makes it difficult for any effects to appear in the measurement accuracy due to air from the surrounding environment penetrating the optical path of the measurement light while using only a simple structure and without causing any excessive energy consumption there are provided a first sealing component provided between an incident surface of a gas cell and a first end surface that is formed at a periphery of an emission aperture of a light-emitting unit soas to enclose the periphery of the emission aperture, and a second sealing component provided between an emission surface of the gas cell and a second end surface that is formed at a periphery of an incident aperture of a light-receiving unit so as to enclose the periphery of the incident aperture.

Description

technical field [0001] The present invention relates to a gas concentration measuring device which introduces gas into a gas cell and measures the concentration of the gas based on the absorbance of the gas. Background technique [0002] For example, in a semiconductor manufacturing process, various liquid materials are heated and vaporized as a material gas, and the material gas is introduced into a vacuum chamber in which a film is formed on a substrate. In order to ensure the quality of the manufactured semiconductor, the concentration of the introduced material gas needs to be kept constant. [0003] In order to perform the concentration control, a gas concentration measuring device that measures the concentration of the material gas based on the NIR method (Near Infrared Spectroscopy) is installed in the room. [0004] The gas concentration measuring device includes: a gas cell, into which the material gas is introduced; a first optical fiber, one end of which is intro...

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Problems solved by technology

[0007] However, if there is a gap between each holder and the gas cell, ambient air may flow into the gap and enter the optical path of the measurement light, and the absorbance of the measurement light may be affected by gases other than the material gas.

In addition, when the gas cell is heated by the heating mechanism to prevent the sample gas from being liquefied again, since the temperature of the lens is lower than that of the surrounding air heated by the heating mechanism, condensation may occur on the lens and cause the optical system to be damaged. changes in the characteristics of

However, if the entire gas concentration measuring device is covered with a casing, and the ambient air temperature is controlled to be constant, the heating of the gas cell and the cooling of each holder are simultaneously controlled in opposite directions, wasting energy in the entire system

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