Localized-Heating Support Plate for Wafer Cold Spot Compensation
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Solution Overview
Problem
Thermal processing systems for semiconductor wafers often result in cold spots due to the obstruction of light by support pins and the added thermal mass, leading to non-uniform heating and reduced heat-up rates, especially in rapid thermal processing applications.
Innovation Solution
A support plate with spatially arranged low transmission zones and a rotatable design that uses a coherent light source to locally heat areas contacting the support pins, compensating for cold spots by modifying the optical transmittance of the support plate and synchronizing the coherent light emission with the rotation of the support plate to ensure uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If support pins are used to hold the workpiece, then the workpiece is supported and positioned, but cold spots are created due to light obstruction and thermal mass
Solution Approach 1:
The support plate is designed with spatially varying optical transmittance properties. Specific regions (first regions) have higher light transmittance while other regions (second regions) have lower transmittance. This local differentiation allows light to pass through selected areas to heat contact zones, compensating for cold spots created by support pins while maintaining structural support functionality.
2Object-affected harmful factors
If the support plate is made opaque to block light, then light obstruction is prevented, but heating flux at contact areas is reduced
Solution Approach 1:
The support plate incorporates regions with different optical transmittance characteristics. First regions are designed with higher light transmittance to allow heating flux to pass through to contact areas, while second regions have lower transmittance to block light where support pins are located. This spatially differentiated design resolves the contradiction between preventing light obstruction and maintaining heating flux.
3Ease of manufacture
If the support plate structure is simplified, then manufacturing is easier, but cold spot compensation capability is reduced
Solution Approach 1:
The support plate utilizes controlled variations in optical transmittance parameters achieved through surface treatments, coatings, or material composition gradients. These parameter changes create regions with different light transmission properties without fundamentally altering the basic plate structure, balancing manufacturing simplicity with cold spot compensation functionality.
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
The solution effectively reduces the presence of cold spots and achieves more uniform heating of semiconductor wafers by increasing the heating flux at contact areas and maintaining global temperature uniformity, enhancing the efficiency of thermal processing systems.
Implementation Method 1
a light source operable to emit coherent light through the transmissive support structure such that the coherent light heats a portion of the workpiece contacting the transmissive support structure
Data Source
AI summary
Support plates for localized heating in thermal processing systems to uniformly heat workpieces are provided. In one example implementation, localized heating is achieved by modifying a heat transmittance of a support plate such that one or more portions of the support plate proximate the areas that cause cold spots transmit more heat than the rest of the support plate. For example, the one or more portions (e.g., areas proximate to one or more support pins) of the support plate have a higher heat transmittance (e.g., a higher optical transmission) than the rest of the support plate. In another example implementation, localized heating is achieved by heating a workpiece via a coherent light source through a transmissive support structure (e.g., one or more support pins, or a ring support) in addition to heating the workpiece globally by light from heat sources.