Transmission corrected plasma emission using in-situ optical reflectometry
Inventors
TAE, PATRICK • Zhu, Zhaozhao • Erickson, Blake W. • Zhang, Chunlei
Assignees
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Publication Number
US-12442765-B2
Publication Date
2025-10-14
Expiration Date
Abstract
Implementations disclosed describe a system including a light source, an optical sensor, and a processing device. The light source directs, during a first time, a probe light into a processing chamber through a window. The light source ceases, during a second time, directing the probe light into the processing chamber through the window. The optical sensor detects, during the first time, a first intensity of a first light. The first light includes a portion of the probe light reflected from the window and a light transmitted from an environment of the processing chamber through the window. The optical sensor detects, during the second time, a second intensity of a second light. The second light includes the light transmitted from the environment of the processing chamber through the window. The processing device determines, using the first intensity and the second intensity, a transmission coefficient of the window.
Core Innovation
The invention provides an in-situ optical reflectometry approach for plasma optical emission spectroscopy (OES) transmission correction using a processing-chamber window. A light source alternates probe light “on” and “off,” and an optical sensor measures first and second intensities associated with probe-light reflection from the window and window-transmitted light.
Using the first intensity and the second intensity, a processing device determines a transmission characteristic of the window. From the determined window transmission characteristic, the processing device can infer chamber incident intensity and separate plasma-environment drifts from window-condition drifts over time.
The document also describes reference transmission concepts for a new/clean window and extensions to wavelength-resolved or broadband measurements, including wavelength-dependent transmission. It further describes geometric and temporal variants, including directing probe light at near-normal incidence and using time-gated (“on”/“off”) measurements to support determining the window transmission characteristic.
Claims Coverage
The document contains three independent claims that each require detecting first and second intensities from probe light interacting with a window and determining a transmission characteristic of the window using those intensities. The inventive features focus on separating reflected-probe-plus-transmitted light from transmitted-only light and using both measurements for in-situ window transmission correction.
First and second intensity detection for window transmission characteristic determination
Detect a first intensity of a first beam of light comprising a portion, reflected from a window, of a probe light directed to the window and a light transmitted through the window; detect a second intensity of a second beam of light comprising the light transmitted through the window; and determine, using the first intensity and the second intensity, a transmission characteristic of the window.
Common optical path intensity sensing in a processing chamber window system
A processing chamber comprising a body comprising a window; an optical sensor to detect a first intensity of a first optical signal wherein the reflected portion of the probe optical signal from the window and the optical signal transmitted from an environment of the processing chamber through the window follow a common optical path; detect a second intensity of a second optical signal comprising the optical signal transmitted from the environment through the window; and a processing device to determine, using the first intensity and the second intensity, a transmission characteristic of the window.
Time-phased probe illumination and transmission characteristic determination from first and second intensities
Detecting a first intensity of a first beam of light comprising a portion, reflected from a window, of a probe light directed to the window and a light transmitted through the window; detecting a second intensity of a second beam of light comprising the light transmitted through the window; and determining, using the first intensity and the second intensity, a transmission characteristic of the window.
Across the independent claims, the core coverage is the measurement of first and second intensities corresponding to reflected probe light and window-transmitted light, followed by determining a window transmission characteristic from those two measurements, including implementation in an optical sensor and processing-chamber system with a window exposed to a processing-chamber environment.
Stated Advantages
Allows transmission correction of plasma optical emission spectroscopy (OES) through a processing-chamber window.
Supports separating plasma-environment drifts from window-condition drifts over time.
Supports determining window transmission characteristic using in-situ optical reflectometry with “on”/“off” probe measurements.
Enables extensions to wavelength-resolved or broadband measurements and wavelength-dependent transmission.
Supports using a reference transmission concept for a new/clean window.
Documented Applications
In-situ optical reflectometry transmission correction of plasma optical emission spectroscopy (OES) through a processing-chamber window.
Processing-chamber monitoring to separate plasma-environment drifts from window-condition drifts over time.
Reference transmission comparison using a new/clean window concept, including pre-coated thin films.
Wavelength-resolved or broadband window transmission determination, including multi-wavelength determination.
Time-domain (“on”/“off”) measurement variants for determining window transmission characteristic.
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