Semiconductor Workpiece Temperature Monitoring via High Emissivity Coating
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Solution Overview
Problem
Current temperature measurement techniques for silicon workpieces in semiconductor processing are limited by silicon's variable emissivity and transparency at infrared frequencies, making it difficult to accurately measure the workpiece temperature, especially in rotating processing devices where only a portion of the workpiece is visible at a time.
Innovation Solution
A system using a high emissivity coating on a portion of the workpiece, combined with an infrared camera and controller to capture and stitch thermal images, allowing for accurate temperature measurement of multiple workpieces by minimizing the coating's impact on intrinsic temperature and enabling continuous monitoring as the workpieces rotate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high emissivity coating is applied to the workpiece to enable accurate infrared temperature measurement, then measurement precision is improved, but the coating may affect the intrinsic temperature of the workpiece and surrounding device
Solution Approach 1:
The patent applies emissivity enhancement only to specific locations on the workpiece surface rather than the entire surface. The coating is applied to discrete regions that are visible through the aperture during rotation, allowing accurate temperature measurement without uniformly affecting the thermal properties of the entire workpiece or surrounding device.
Solution Approach 2:
The patent uses partial coating coverage rather than full surface coating. By applying the high emissivity coating to only the portions of the workpiece that need to be monitored and are visible through the aperture, the system achieves sufficient measurement precision while minimizing the total amount of coating material and its thermal impact on the device.
2Productivity
If the workpiece is rotated to process multiple workpieces, then productivity is improved, but continuous monitoring of the entire workpiece becomes difficult
Solution Approach 1:
The patent ensures continuous temperature monitoring capability during workpiece rotation by strategically placing high emissivity coating on portions of the workpiece that will be visible through the aperture at different rotation positions. This allows the infrared sensor to continuously capture temperature data throughout the rotation cycle without interruption or data gaps.
Solution Approach 2:
The high emissivity coating acts as an intermediary that enhances the visibility and detectability of the workpiece surface to the infrared sensor. By applying this coating to specific regions, the system enables the infrared camera to accurately detect temperature through the aperture even when the workpiece is rotating, maintaining continuous monitoring capability.
3Device complexity
If only a portion of the workpiece is visible through the aperture during rotation, then device complexity is reduced, but measurement precision of the entire workpiece deteriorates
Solution Approach 1:
The patent divides the workpiece surface into multiple segments or regions, applying high emissivity coating to specific segments that correspond to different angular positions during rotation. This segmentation allows the simple aperture-based monitoring system to capture temperature data from multiple workpiece regions throughout the rotation cycle, achieving comprehensive temperature mapping without increasing device complexity.
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 and continuous temperature measurement of silicon workpieces across a range of temperatures, improving temperature uniformity monitoring and reducing measurement errors by using a coating with nearly constant emissivity and advanced image stitching technology.
Implementation Method 1
the optical properties of silicon make the application of common infrared techniques difficult or impossible. Specifically, at certain temperatures, silicon is nearly transparent at infrared frequencies
Implementation Method 2
Because silicon has variable emissivity in the infrared band, a temperature stable, high emissivity coating is applied to a portion of the workpiece, allowing the temperature of the workpiece to be measured by observing the temperature of the coating
Data Source
AI summary
An improved system for measuring the temperature of a plurality of workpieces in a rotating semiconductor processing device is disclosed. Because silicon has variable emissivity in the infrared band, a temperature stable, high emissivity coating is applied to a portion of the workpiece, allowing the temperature of the workpiece to be measured by observing the temperature of the coating. Further, by limiting the amount of coating applied to the workpiece, the effect of the coating on the intrinsic temperature of the workpiece and the surrounding semiconductor processing device may be minimized. The temperature of the workpieces is measured as the workpieces pass under an aperture by capturing a thermal image of a portion of the workpiece. In certain embodiments, a controller is used to process the plurality of thermal images into a single thermal image showing all of the workpieces disposed within the semiconductor processing device.