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AssigneeAir Products and Chemicals, Inc.
InventorsBing Ji, Robert Gordon Ridgeway, Eugene Joseph Karwacki, Jr., Howard Paul Withers, Jr., Steven Arthur Rogers, Peter James Maroulis, John Giles Langan
Estimating the term…
An on-line halogen analyzer system and method of use for semiconductor processing effluent monitoring. The system includes sampling the effluent stream into an absorption cell, and passing UV-Visible light through the effluent sample in the cell. After passing through the sample the light is collected by a photo detector for real-time wavelength-selective absorption analysis. The system provides simultaneous determination of the concentrations of multiple halogen gases (e.g. F2, Cl2, Br2, and I2) in semiconductor processing effluent streams. The invention can be used for chemical vapor deposition (CVD) chamber cleaning endpoint determination and to improve fluorine utilization efficiency in remote plasma downstream CVD chamber cleaning processes.
A method for analyzing homonuclear diatomic halogen gases in a process effluent stream comprising the steps of:
An apparatus for detecting the presence of a homonuclear diatomic halogen gases in a sample gas comprising in combination:
A method for detecting the endpoint of a clean operation wherein a halogen gas is used to clean contaminants from internal surfaces of a semiconductor process tool comprising the steps of:
A method for controlling a semiconductor manufacturing processes by monitoring the concentration of homonuclear diatomic halogen gases in a process effluent gas stream comprising the steps of:
Dependencies are inferred from the claim text.
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Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands:…
Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry:…
Investigating or analysing materials by determining their chemical or physical properties
Term ended 27 Mar 2022 (estimated)
1. Field of the Invention
The present invention pertains to a method and apparatus for analyzing effluent streams from various process tools used to make semiconductors, and in particular, to an on-line UV-Visible analyzer system for measuring the concentrations of homonuclear diatomic halogens (F2, Cl2, Br2, and I2) in a gas flow stream, and methods for using the analyzer system.
2. Description of the Related Art
FIG. 1 is a schematic diagram of an on-line UV-Visible analyzer system according to the present invention.
FIG. 2a is a cross-sectional view of the body portion of an absortion cell according to the present invention.
FIG. 2b is a left side elevational view of the absortion cell of FIG. 2a.
The present invention utilizes absorption spectroscopy for detecting and quantifying gas phase halogen species. When light traverses through an absorbing medium, the attenuation (i.e., absorption) of light intensity is related to the concentration of an absorber as prescribed by Beer's Law represented by the equation: log ( I 0 ( λ ) I ( λ ) ) = A ( λ ) = ϵ ( λ ) lc ( 4 )
where I0(λ) is the incident light intensity at wavelength λ, I is the transmitted light intensity at wavelength λ, A(λ) is the absorbance at wavelength λ, ε(λ) is the absorptivity of the specific molecule at wavelength λ, I is the optical path length, and c is the concentration of the absorbing molecule. Homonuclear diatomic halogen vapors (F2, Cl2, Br2, and I2) all absorb in the UV-Visible range of the spectrum between 200 and 600 nm. The optical path length I is fixed for a particular absorption cell setup. The absorptivity coefficient ε(λ) is a constant characteristic of the molecule and the measurement wavelength. ε(λ) can be accurately determined by calibrating the response of the system with a known reference sample. Once the system is calibrated, one can use Beer's Law (Equation 4) to determine the concentrations of the absorbing molecule. The light intensity ratio in Beer's Law allows the effect of changes in light throughput of the system to be cancelled out. Therefore, the system is robust under severe application conditions often encountered in semiconductor processing effluent streams. Minor coating of the windows with process residues and/or pitting will not cause unacceptable system response drift and hence no frequent re-calibration is needed.
When multiple absorbing species are present, the total absorbance is the sum of each constituent according to the equation: A ( λ ) = ∑ i ϵ i ( λ ) lc i ( 5 )