Focus Ring Temperature Measurement via Low-Coherence Light
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Solution Overview
Problem
Conventional temperature measuring technologies using low-coherence light interference thermometers fail to accurately measure temperatures when the measured target's surfaces become non-parallel due to abrasion in plasma-exposed components, such as focus rings, in substrate processing apparatuses.
Innovation Solution
A component with a temperature measuring apparatus using low-coherence light interference, featuring a temperature measured portion with parallel surfaces at the abrasive and nonabrasive sides, coated with materials like silicon, silicon carbide, or sapphire, and a heat transfer sheet or gas for accurate temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low-coherence light interference thermometer is used to measure temperature, then temperature measurement capability is provided, but measurement accuracy deteriorates when surfaces become non-parallel due to abrasion
Solution Approach 1:
The focus ring is divided into two distinct surfaces: an abrasive surface exposed to plasma that undergoes wear, and a nonabrasive surface protected from plasma that maintains its parallelism. The temperature measuring apparatus measures temperature through the nonabrasive surface, which remains parallel throughout the component's service life, thereby maintaining measurement accuracy despite abrasion of the opposing surface.
Solution Approach 2:
The measurement function is extracted from the abrasive interface and relocated to the nonabrasive surface. By measuring temperature through the nonabrasive surface that does not contact plasma, the system separates the measurement pathway from the wear pathway, ensuring that abrasion does not affect measurement quality.
2Productivity
If the focus ring is exposed to plasma for processing, then substrate processing capability is provided, but surface parallelism deteriorates due to abrasion loss
Solution Approach 1:
Different surfaces of the focus ring are given different functional qualities: the abrasive surface is designed to withstand plasma exposure and controlled wear, while the nonabrasive surface is designed to maintain parallelism and serve as a stable measurement interface. This local differentiation allows the component to simultaneously achieve processing capability and measurement stability.
Solution Approach 2:
The focus ring functionality is segmented into plasma-facing operations (abrasive surface) and measurement operations (nonabrasive surface). This segmentation allows independent optimization of each function without compromise.
3Reliability
If the focus ring is monitored for abrasion loss, then replacement timing is determined, but temperature measurement accuracy is lost when parallelism is exceeded
Solution Approach 1:
The temperature measurement function is extracted from the abrasive surface and relocated to the nonabrasive surface. This extraction allows abrasion monitoring to continue on the abrasive surface while temperature measurement maintains accuracy on the protected nonabrasive surface, eliminating the trade-off between these two measurement needs.
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
Enables accurate temperature measurement of components in substrate processing chambers even when surfaces are no longer parallel due to abrasion, maintaining measurement precision and extending the lifespan of components by protecting them from plasma wear.
Implementation Method 1
measuring interference between a reference light and reflection lights from a front surface and the rear surface
Data Source
AI summary
A component in a processing chamber of a substrate processing apparatus, where a temperature may be accurately measured by using a temperature measuring apparatus using an interference of a low-coherence light, even when a front surface and a rear surface are not parallel due to abrasion, or the like. A focus ring used in a vacuum atmosphere and of which a temperature is measured includes an abrasive surface exposed to an abrasive atmosphere according to plasma, a nonabrasive surface not exposed to the abrasive atmosphere, a thin-walled portion including a top surface and a bottom surface that are parallel to each other, and a coating member coating the top surface of the thin-walled portion, wherein a mirror-like finishing is performed on each of the top and bottom surfaces of the thin-walled portion.