Ceramic Heater Temperature Uniformity via Metal Mesh Resistive Elements
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Solution Overview
Problem
Ceramic heaters used in semiconductor manufacturing face challenges in maintaining temperature uniformity on the wafer-heating surface, as the formation of molybdenum carbide in resistive heating elements leads to uneven resistance and heat generation, impairing temperature uniformity and increasing costs due to the need for dummy members.
Innovation Solution
A method involving hot-press firing at 1,600° C. to 1,750° C. using an inner shaped body with low-temperature sinterable aluminum nitride powder and rare earth oxide, sandwiched between outer aluminum nitride sintered bodies with high volume resistivity, and resistive heating elements composed of metal meshes to reduce molybdenum carbide formation and enhance temperature uniformity without using dummy members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If dummy members are embedded in the shaped body during sintering to control molybdenum carbide formation, then temperature uniformity on the heating surface is improved, but the device complexity and manufacturing cost increase due to the requirement of dummy members and subsequent machining removal
Solution Approach 1:
The invention extracts and eliminates the dummy members from the heating structure by redesigning the sintering process. Instead of embedding and later removing dummy members, the patent uses a multi-layer green body structure where the functional layers are directly formed during sintering without requiring temporary placeholder components, thereby simplifying the device structure while maintaining temperature uniformity.
Solution Approach 2:
The invention applies preliminary action by pre-forming the multi-layer green body structure with aluminum nitride layers and molybdenum layers in the correct configuration before sintering. This preliminary structuring ensures that the desired layer distribution and thickness are achieved before the sintering process, eliminating the need for dummy members and subsequent machining operations.
2Temperature
If dummy members are used and removed by machining to control resistance distribution, then temperature uniformity is improved, but manufacturing cost increases due to additional materials and processing steps
Solution Approach 1:
The invention performs preliminary action by forming the multi-layer green body structure with precise layer thicknesses and compositions before sintering. This preliminary preparation ensures that the final sintered product achieves the desired resistance distribution and temperature uniformity without requiring additional machining or dummy member removal steps, thereby reducing manufacturing cost.
Solution Approach 2:
The invention extracts and eliminates the need for dummy members and their associated machining operations by directly forming the functional multi-layer structure during sintering. This approach removes unnecessary material and processing steps, thereby reducing manufacturing cost while maintaining temperature uniformity.
3Stability of the object's composition
If high sintering temperature of 1,800° C. or higher is used to sinter the shaped body, then sintering completeness is achieved, but molybdenum carbide formation increases leading to uneven resistance and impaired temperature uniformity
Solution Approach 1:
The invention applies parameter changes by optimizing the sintering temperature to a specific range that balances sintering completeness with control of molybdenum carbide formation. By carefully selecting and controlling the sintering temperature parameter, the patent achieves adequate densification while minimizing unwanted carbide formation that would cause resistance non-uniformity.
Solution Approach 2:
The invention uses composite materials by creating a multi-layer structure combining aluminum nitride and molybdenum layers with specific thickness ratios. This composite structure controls the interaction between materials during sintering, limiting molybdenum carbide formation while achieving complete sintering of the aluminum nitride matrix, thereby maintaining both structural integrity and electrical uniformity.
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 approach achieves high temperature uniformity on the heating surface, preventing current leakage and maintaining designed resistance distribution, making the ceramic heater suitable for semiconductor thin film formation with reduced costs by eliminating the need for dummy members.
Implementation Method 1
resistive heating elements composed of metal meshes
Implementation Method 2
performing hot-press firing at 1,600° C. to 1,750° C.
Data Source
AI summary
A method for producing a ceramic heater includes performing firing at 1,600° C. to 1,750° C. in a state in which front and back surfaces of an inner shaped body composed of low-temperature sinterable raw material powder containing aluminum nitride powder as a main component and 0.03% to 1% by weight of rare earth oxide powder are sandwiched between a pair of outer layers composed of aluminum nitride sintered bodies having a volume resistivity of 1015 Ωcm or more through resistive heating elements composed of metal meshes, thereby obtaining a ceramic heater.