Ceramic Heater Turning-Back Segments for Uniform Temperature
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Solution Overview
Problem
Ceramic heaters used in electrostatic chucks for semiconductor wafers often experience nonuniform temperature distribution due to through holes, leading to inefficiencies in heating and cooling, as the heat-generating elements must detour around these holes, increasing resistance and making temperature control challenging.
Innovation Solution
The ceramic heater design incorporates turning-back segments in the heat-generating conductor to prevent parallel segments from overlapping through holes, maintaining uniform spacing and reducing resistance differences between heating zones, thereby achieving uniform in-plane temperature distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat-generating elements detour around through holes, then the elements can be formed without overlapping holes, but the spacing between parallel segments becomes small and temperature distribution becomes nonuniform
Solution Approach 1:
The heat-generating element is divided into multiple parallel segments with turning-back segments connecting them. This segmentation allows the element to navigate around through holes while maintaining adequate spacing between parallel segments, preventing localized overheating and achieving uniform temperature distribution across the heating zone.
Solution Approach 2:
The heat-generating element transitions from a simple linear path to a two-dimensional pattern with turning-back segments that extend in multiple directions. This dimensional change enables the element to route around through holes effectively while maintaining optimal spacing, resolving the conflict between avoiding holes and maintaining temperature uniformity.
2Reliability
If heat-generating elements detour around through holes, then the elements can avoid holes, but the resistance increases and temperature control becomes challenging
Solution Approach 1:
The turning-back segments are strategically positioned only where needed to navigate around through holes, rather than uniformly throughout the entire heat-generating element. This localized approach maintains adequate spacing and resistance characteristics in critical areas while keeping the overall design simple and temperature control manageable.
3Area of stationary object
If parallel segments are disposed close together to detour around holes, then the element can fit around holes, but the small spacing causes higher temperature in that region
Solution Approach 1:
The turning-back segments use curved paths rather than sharp angles to transition between parallel segments. This curvature distributes the heat generation more evenly and avoids creating concentrated hot spots, while still effectively routing around through holes and maintaining adequate spacing.
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
This design ensures uniform temperature distribution across the ceramic heater, improving temperature controllability and reducing the complexity of adjusting control parameters, even when heating zones with and without holes are subjected to the same conditions.
Implementation Method 1
a zone heat-generating element disposed in a certain one of the heating zones having the hole region is formed of a linear heat-generating conductor
Implementation Method 2
By use of electrostatic attraction generated through application of voltage to the chucking electrodes, the electrostatic chuck chucks the semiconductor wafer on the upper surface
Data Source
AI summary
As viewed in plane, a ceramic heater includes zone heat-generating elements disposed in respective heating zones so as to heat a ceramic substrate independently. In the heating zone having a hole region, the zone heat-generating element is formed of a linear heat-generating conductor which has parallel segments disposed in parallel, and a turning-back segment which connects, while turning back, the parallel segment of the heat-generating conductor extending toward the hole region to the adjacent parallel segment of the heat-generating conductor so as to prevent the parallel segment extending toward the hole region from overlying the hole region.