Ceramic Heater Circuit Layout to Prevent Terminal-Hole Cool Spots
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Solution Overview
Problem
Ceramic heaters used in semiconductor manufacturing face challenges in maintaining temperature uniformity, with issues such as heater coil exposure in terminal holes leading to cracks and cool spots, which cause tensile thermal stress.
Innovation Solution
A ceramic heater design featuring a heater coil part and a heater element wire part arranged at the same or deeper depth, preventing coil exposure in terminal holes and cool spots, using a heater circuit with a coil form and element wire form resistive heating elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heater coil is arranged to stay away from the heater terminal hole to avoid exposure, then the reliability is improved, but a cool spot locally having a low temperature may be caused instead by insufficient heat generation
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement to a three-dimensional spatial arrangement by positioning the heater coil at a deeper depth within the ceramic plate, away from the terminal hole opening. This depth dimension allows the coil to be protected from exposure while maintaining thermal coverage through vertical heat distribution.
Solution Approach 2:
The patent applies different spatial positioning strategies to different components: the heater coil is positioned at a deeper depth away from the terminal hole to prevent exposure and cool spots, while the heater element wire is positioned closer to the terminal hole for efficient electrical connection. This localized differentiation resolves the contradiction between reliability and temperature uniformity.
2Temperature
If a smaller heater terminal hole is used to enhance temperature uniformity, then the temperature uniformity is improved, but the miniaturization is limited because the electric current flowing through the resistive heating element tends to increase as process temperature becomes higher
Solution Approach 1:
The patent utilizes the depth dimension within the ceramic plate to position the heater coil away from the terminal hole opening. This allows the terminal hole to be minimized for temperature uniformity while the coil resides deeper inside, preventing exposure and managing current density through spatial separation.
3Power
If the heater coil part is arranged at a shallower depth to maximize heat generation, then the heat generation is improved, but the heater coil part may be exposed in the heater terminal hole causing cracks
Solution Approach 1:
The patent positions the heater coil at an optimized depth within the ceramic plate, away from the terminal hole opening. This depth positioning allows the coil to generate sufficient heat through resistive heating while being protected from exposure that would cause cracks, resolving the contradiction between power output and reliability.
Solution Approach 2:
The patent applies differentiated positioning: the heater coil is positioned at a deeper depth for protection and adequate heat generation, while the heater element wire is positioned closer to the terminal hole for efficient electrical connection. This localized quality differentiation resolves the contradiction between heat generation and crack prevention.
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
Prevents cracks and cool spots, ensuring temperature uniformity and reducing thermal stress, thereby enhancing the reliability and performance of the ceramic heater.
Implementation Method 1
a heater circuit embedded in the ceramic plate... composed of a resistive heating element in a coil form
Data Source
AI summary
There is provided a ceramic heater including: a ceramic plate having a first surface and a second surface; a heater circuit embedded therein; spherical terminals connected thereto; heater terminal holes; and heater rods that are inserted in the heater terminal holes respectively, are electrically connected to the spherical terminals, and extend in a direction away from the first surface. The heater circuit includes: a heater coil part positioned parallel to the first surface; and a heater element wire part composed of a resistive heating element in an element wire form, so as to extend from the heater coil part and so that a tip end thereof reaches an inside of the spherical terminals. In a cross-sectional view, the heater element wire part is arranged at a same depth position as a lower end of the heater coil part or at a deeper depth position closer to the second surface.