Small-Diameter Sheath Heater Layout for Thermal Expansion Reliability
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Solution Overview
Problem
The existing sheath heater designs for semiconductor manufacturing processes, particularly those using stainless steel sheaths and nickel-chromium alloy heating wires, do not adequately address the issue of thermal expansion differences, leading to potential disconnection and reliability concerns.
Innovation Solution
A sheath heater unit with a double helical heating wire arrangement within a metal sheath, where the sheath and substrate materials have a low thermal expansion coefficient mismatch, and are joined using the same metal material, such as aluminum, with insulating materials like magnesium oxide to enhance reliability and precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stainless steel sheath and nickel-chromium alloy heating wire are used, then heating function is achieved, but thermal expansion difference causes disconnection and reliability degradation
Solution Approach 1:
The patent applies homogeneity by using the same material (stainless steel) for both the sheath and the heating wire, eliminating material heterogeneity. This ensures that both components have identical thermal expansion coefficients, preventing disconnection caused by differential thermal expansion during heating cycles.
Solution Approach 2:
The patent changes the material parameter of the heating wire from nickel-chromium alloy to stainless steel, matching the sheath material. This parameter change (material composition) directly addresses the thermal expansion mismatch issue while maintaining the heating functionality through the stainless steel wire's resistive heating properties.
2Power
If heating wire is embedded in metal sheath, then heating function is provided, but thermal expansion mismatch leads to disconnection
Solution Approach 1:
By making both the sheath and heating wire from the same stainless steel material, the patent eliminates the thermal expansion mismatch that would otherwise cause the heating wire to disconnect from electrodes during thermal cycling, thereby maintaining both heating power and reliability.
3Adaptability or versatility
If different materials are used for sheath and heating wire, then functional requirements are met, but thermal expansion difference causes disconnection
Solution Approach 1:
The patent restricts material selection to stainless steel for both components, sacrificing some material versatility to ensure thermal expansion compatibility. This homogeneous material approach guarantees connection stability during thermal cycles while still meeting the heating functional requirement through the stainless steel wire's electrical resistivity.
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 reduces the risk of disconnection during thermal expansion and provides a more reliable and precise temperature distribution across the semiconductor substrate, enabling uniform film formation and processing.
Implementation Method 1
a sheath heater, which is a heating mechanism, is embedded in the stage in a meandering or spiral shape
Implementation Method 2
one of said sheath member and said panel member is formed by a first material capable of being alloyed with, and having a coefficient of thermal expansion close to a coefficient of thermal expansion of, a second material for the other of said sheath member and said panel member
Data Source
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AI summary
A heater unit including a small diameter sheath heater with improved reliability is provided. The heater unit includes a first substrate and a second substrate joined together, a groove arranged on at least one join surface of the first substrate and the second substrate, and a sheath heater arranged inside the groove. The sheath heater includes a metal sheath, a heating wire having a band shape, the heating wire arranged with a space within the metal sheath so as to rotate with respect to an axis direction of the metal sheath, an insulating material arranged in the space, and connection terminals arranged at one end of the metal sheath, connection terminals electrically connected with both ends of the heating wire respectively.