Increasing the sensitivity of an in-situ particle monitor
First Claim
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1. An in situ particle monitoring system of monitoring particles in a plasma within a processing chamber of a substrate processing system for processing a substrate, said particle monitoring system comprising:
- a particle concentrator for concentrating at least a portion of the particles into a reduced volume which is smaller than an original volume occupied by said particles;
an optically transparent window in a wall of the processing chamber;
a light source for illuminating at least a portion of said reduced volume through said optically transparent window; and
an optical detector for detecting at least some light scattered by at least some particles in said at least a portion of said reduced volume and exiting the processing chamber through said optically transparent window.
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Abstract
A method and apparatus for increasing the sensitivity of an in situ particle monitor. A light scattering technique, preferably using laser light, is employed to monitor particle concentrations within the processing chamber of a plasma-based substrate processing system. Particle concentrations are increased in the light field of the sensor by creating an electric or magnetic field in the processing chamber to concentrate the particles suspended therein.
419 Citations
31 Claims
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1. An in situ particle monitoring system of monitoring particles in a plasma within a processing chamber of a substrate processing system for processing a substrate, said particle monitoring system comprising:
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a particle concentrator for concentrating at least a portion of the particles into a reduced volume which is smaller than an original volume occupied by said particles; an optically transparent window in a wall of the processing chamber; a light source for illuminating at least a portion of said reduced volume through said optically transparent window; and an optical detector for detecting at least some light scattered by at least some particles in said at least a portion of said reduced volume and exiting the processing chamber through said optically transparent window. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An in situ particle monitoring system for monitoring particles in a plasma within a processing chamber of a substrate processing system, said particle monitoring system comprising:
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a particle concentrator for concentrating at least a portion of the particles into a reduced volume which is smaller than an original volume occupied by said particles; first and second optically transparent windows in a wall of the processing chamber; a light source for illuminating at least a portion of said reduced volume through said first optically transparent window; and an optical detector for detecting at least some light scattered by at least some particles in said at least a portion of said reduced volume and exiting the processing chamber through said second optically transparent window. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for detecting particles using a particle concentration monitor having improved sensitivity, the particle concentration monitor having a light source for creating a light field and a detector having a field of view, for monitoring particles within a processing chamber of a substrate processing system for processing a substrate, said method comprising the steps of:
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creating a plasma within the processing chamber, said plasma causing a portion of the particles to acquire a static electrical charge; and applying an electric field to said portion of the particles to concentrate said portion of the particles within a reduced volume in conformance with said electric field, said reduced volume being smaller than an original volume occupied by said particles and being at least partially within the light field and the field of view. - View Dependent Claims (21, 22, 23, 24)
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25. A method for improving the sensitivity of a particle concentration monitor, the particle concentration monitor having a light source for creating a light field and a detector having a field of view, for monitoring particles within a processing chamber of a substrate processing system for processing a substrate, said method comprising the steps of:
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creating a plasma within the processing chamber, said plasma causing a portion of the particles to acquire a static electrical charge; and applying a magnetic field to said portion of the particles to concentrate said portion of the particles within a reduced volume in conformance with said magnetic field, said reduced volume being smaller than an original volume occupied by said particles and being at least partially within the light field and the field of view. - View Dependent Claims (26, 27, 28, 29)
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30. A method of monitoring the concentration of particles in a processing chamber of a substrate processing system using a light-scattering particle concentration monitor, the monitor having a light source for creating a light field and a detector having a field of view, said method comprising the steps of:
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creating a plasma within the processing chamber, said plasma causing the particles to acquire a static electrical charge; applying an electric field to the particles to concentrate a first portion of the particles into a reduced volume in conformance with said electric field, said reduced volume being smaller than an original volume occupied by said particles, a portion of said reduced volume being at least partially within the light field and the field of view; illuminating said portion of said reduced volume using the light source; and detecting light scattered from particles within said portion of said reduced volume using the detector.
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31. A method of monitoring the concentration of particles in a processing chamber of a substrate processing system using a light-scattering particle concentration monitor, the monitor having a light source for creating a light field and a detector having a field of view, said method comprising the steps of:
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creating a plasma within the processing chamber, said plasma causing the particles to acquire a static electrical charge; applying a magnetic field to the particles to concentrate a first portion of the particles into a reduced volume in conformance with said magnetic field, said reduced volume being smaller than an original volume occupied by said particles, a portion of said reduced volume being at least partially within the light field and the field of view; illuminating said portion of said reduced volume using the light source; and detecting light scattered from particles within said portion of said reduced volume using the detector.
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Specification