Heater Unit Shaft With Differential Heat Conduction
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Solution Overview
Problem
Conventional heater units for semiconductor substrates experience temperature non-uniformity issues due to varying heating times across different areas, particularly around the hollow area formed by the shaft axis, when repeatedly switching the resistance heating element between heated and non-heated states.
Innovation Solution
A heater unit design featuring a shaft with a radial external part made of a high heat conductor and a radial internal part made of a lower heat conductor, along with a flange part and an expanded diameter section with an O ring groove, which reduces heat conduction to the O ring, allowing for improved temperature uniformity and simplified assembly without the need for additional fixing components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional shaft with uniform heat conduction is used, then the structure is simple, but temperature uniformity deteriorates in areas confronting the hollow axis
Solution Approach 1:
The shaft is designed with different heat conduction properties in different regions: the radial external part uses a first heat conductor with higher heat conduction, while the radial internal part uses a second heat conductor with lower heat conduction. This local differentiation of material properties resolves the temperature uniformity issue without requiring complete structural redesign.
Solution Approach 2:
The shaft employs a composite structure combining two different heat conductor materials with distinct thermal conductivity characteristics. The first heat conductor (higher conductivity) and second heat conductor (lower conductivity) are arranged in specific spatial relationships to achieve optimal temperature distribution, demonstrating the application of composite material principles.
2Productivity
If the heating element is repeatedly switched between heated and non-heated states, then energy efficiency is improved, but heating time increases in areas confronting the hollow axis
Solution Approach 1:
The differential heat conduction design addresses the localized heating delay in the hollow axis confrontation area by providing enhanced heat conduction through the first heat conductor in the radial external part, compensating for the thermal lag experienced during repeated heating cycles.
3Reliability
If the O ring is positioned close to the heating element, then sealing effectiveness is improved, but the O ring requires cooling to maintain material integrity
Solution Approach 1:
The second heat conductor with lower heat conduction acts as a thermal intermediary or buffer between the heating element and the O ring. By positioning the O ring adjacent to this lower conductivity material, the design reduces heat transfer to the O ring while maintaining sealing effectiveness, thereby eliminating the need for additional cooling mechanisms.
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 design shortens the time required to reach desired heating temperatures, especially in areas confronting the hollow axis, and eliminates the need for cooling the O ring, enabling the use of materials with lower temperature limits, thus enhancing temperature uniformity and ease of assembly.
Implementation Method 1
The radial external part of the shaft is formed by a first heat conductor and has a higher heat conduction ratio
Implementation Method 2
The radial internal part of the shaft is formed by a second heat conductor and has a lower heat conduction ratio than the first heat conductor
Implementation Method 3
a resistance heating element is routed through the inner section of the heater plate passing through the shaft part. It is a mechanism whereby when a current is passed along the resistance heating element, the resistance heating element generates heat
Data Source
AI summary
The present invention provides a heater unit which can improve temperature uniformity of a heated object at the time of heating the object. A second heat conductor 32 which is the radial internal part of shaft 22 has a lower heat transfer ratio than a first heat conductor 30 which is the radial external part of shaft 22. As a result, in the case where a heated state and a non heated state of the resistance heating element 18 are repeatedly switched, the movement of heat from the front part 22B of the shaft 22 to the base point part 22A is suppressed by the second heat conductor 32 compared to the first heat conductor 30. As a result, in the part which confronts the hollow part 42 of the shaft 22 in the heater plate 16, the time required to heat the heater plate 16 and the wafer 28 to be heated to a desired heating temperature is shortened when compared to a conventional heater unit. Therefore, it is possible to improve the uniformity of the temperature of the wafer 28 which is to be heated by the heater plate 16.