Pyrometer Stray Radiation Filtration via Signal Subtraction
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Solution Overview
Problem
Pyrometers in rapid thermal processing chambers face noise interference from radiation sources, such as lamps, which distorts temperature measurements, and existing shielding methods are inadequate, especially when pyrometers are positioned on the same side as the lamphead.
Innovation Solution
A system that includes a processing chamber, substrate support, pyrometer, and controller, which measures and subtracts time-invariant and time-variant noise components from the pyrometer signal to separate lamp noise from substrate radiation, using first-order time-response values and steady-state values to correct temperature readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical shielding or blocking is used to prevent stray radiation from reaching the pyrometer, then noise reduction is improved, but the shielding may be insufficient to prevent noise while allowing proper radiation to pass, and such shielding approaches are not feasible when pyrometers are positioned on the same side as the lamphead
Solution Approach 1:
The patent extracts and removes the harmful noise component from the pyrometer signal through mathematical subtraction. The controller separates the noise component from the substrate radiation component and subtracts it, leaving only the accurate substrate temperature signal. This eliminates the need for complex mechanical shielding structures.
Solution Approach 2:
The patent replaces the mechanical shielding approach with an electronic/digital signal processing solution. Instead of using physical barriers to block stray radiation, the system uses software-based noise subtraction to remove the lamp radiation component from the pyrometer signal, achieving the same goal without mechanical complexity.
2Ease of operation
If pyrometers are positioned on the same side as the lamphead to enable certain applications, then ease of operation is improved, but noise interference from lamps distorts the detected radiation at the pyrometer
Solution Approach 1:
The patent converts the harmful lamp noise into a useful component by measuring and characterizing it separately. The system measures the lamp radiation component and uses this information to subtract the noise from the total signal, transforming the harmful interference into a correctable parameter that improves measurement accuracy.
Solution Approach 2:
The patent segments the pyrometer signal into distinct components: substrate radiation and lamp noise. By separating these components through mathematical analysis and subtracting the lamp component, the system recovers the pure substrate temperature signal while maintaining the operational flexibility of having pyrometers on the same side as the lamphead.
3Measurement precision
If noise correction is performed by subtracting time-invariant and time-variant noise components, then measurement precision is improved, but device complexity increases due to the need for noise measurement and correction algorithms
Solution Approach 1:
The patent implements a feedback-based noise correction system where the controller continuously measures the pyrometer signal, separates the noise component, subtracts it, and outputs the corrected temperature. This closed-loop approach automatically adapts to changing conditions and maintains high measurement precision without requiring complex manual intervention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively separates noise from actual temperature measurements, providing accurate substrate temperature readings by averaging first-order time-response values and subtracting noise components, thus improving the precision of thermal processing control.
Implementation Method 1
The pyrometer is positioned to receive radiation emitted by a substrate or a component of the processing chamber and generating a pyrometer signal indicative of the received radiation
Implementation Method 2
The controller is configured to subtract a time invariant noise component and a time variant noise component from the pyrometer signal during processing of a substrate
Implementation Method 3
A number of infrared lamps are located in the lamphead. During processing, radiation from the lamps radiates through an upper window, light passageways and a lower window onto a rotating semiconductor substrate in the processing chamber. In this manner, the wafer is heated to a required processing temperature
Data Source
AI summary
The embodiments described herein generally relate to systems for noise compensation for proper temperature detection in thermal processing chambers and devices for achieving the same. In one embodiment, a system is disclosed herein. The system includes a processing chamber, a substrate, a pyrometer, and a controller. The processing chamber is configured to process a substrate. The substrate support is disposed in the processing chamber. The pyrometer is positioned to receive radiation emitted by a substrate or a component of the processing chamber and generating a pyrometer signal indicative of the received radiation. The controller is configured to subtract a time invariant noise component and a time variant noise component from the pyrometer signal during processing of a substrate.