Ceramic Heater Stage Composition for Stable High-Temperature Resistance
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Solution Overview
Problem
Ceramic heaters used in substrate mounting stages for semiconductor manufacturing face limitations due to high thermal conductivity and low resistance, leading to significant changes in volume resistance with temperature increases, which can result in accelerated degradation when high power is continuously applied.
Innovation Solution
A heater stage design featuring an insulating ceramic substrate with a heat generating element composed of a ceramic composite material including metal nitrides and metal oxides, such as AlN or Al2O3, with a higher content of ceramic and metal carbide, achieving a relative density of 95% or more and a volume resistance of 1.0 Ω·cm or less at room temperature, and a controlled rate of change in resistance with temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single material (SiC) is used for the heat generating element, then high thermal conductivity and low resistance are achieved, but the volume resistance value changes significantly with temperature increase
Solution Approach 1:
The patent applies composite materials by combining ceramic (AlN or Al2O3) with metal carbide (TiC, ZrC, HfC, MoC, TaC, or WC) in specific ratios. This composite structure resolves the contradiction by providing both the electrical conductivity needed for heat generation and the thermal stability to minimize resistance changes with temperature. The ceramic component provides thermal stability while the metal carbide component provides electrical conductivity, achieving a balance that single materials cannot provide.
Solution Approach 2:
The patent applies parameter changes by optimizing the compositional ratios of ceramic to metal carbide (5:5 to 9:1 by weight) and controlling the relative density (90-99%). By adjusting these parameters, the volume resistance value is controlled within 0.1-10.0 Ω·cm at room temperature, and the rate of change with temperature is limited to 0.01-0.5 per 100°C. This parametric optimization resolves the contradiction between maintaining low resistance and minimizing resistance variation with temperature.
2Power
If high power is continuously supplied to the heat generating element, then the required heat generation is satisfied, but the heat generating element degrades faster
Solution Approach 1:
The composite material structure provides both high electrical conductivity for efficient power utilization and high thermal stability for durability. The ceramic component (AlN or Al2O3) offers excellent thermal stability and resistance to thermal degradation, while the metal carbide component provides high electrical conductivity for efficient power conversion to heat. This combination enables continuous high-power operation without accelerated degradation.
Solution Approach 2:
By optimizing the relative density to 90-99% and controlling the compositional ratios, the material achieves a balance between electrical conductivity (for power efficiency) and thermal stability (for durability). This parametric control ensures that the heat generating element can continuously operate at high power levels without excessive degradation, resolving the contradiction between power output and component lifespan.
3Use of energy by moving object
If ceramic material volume resistance decreases with temperature increase, then heat generation efficiency improves, but more power is needed to maintain required heat generation
Solution Approach 1:
The patent controls the volume resistance value within 0.1-10.0 Ω·cm at room temperature and limits the rate of change with temperature to 0.01-0.5 per 100°C through compositional optimization. This parametric control ensures stable electrical conductivity across the operating temperature range, maintaining consistent heat generation efficiency without requiring increasing power input as temperature rises, thus resolving the contradiction between efficiency and power consumption.
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 reduces the variability of electric current and improves the reliability of the heater stage by minimizing resistance changes with temperature, enhancing heat transfer efficiency and reducing thermal stress, while maintaining uniform temperature distribution across the substrate.
Implementation Method 1
a heat generating element located between the lower substrate and the upper substrate and including a second ceramic and a second metal carbide
Data Source
AI summary
A heater stage includes an insulating ceramic substrate including lower and upper substrates, each including a first ceramic, and a heat generating element located between the lower substrate and the upper substrate and including a second ceramic and a second metal carbide. The first ceramic of the insulating ceramic substrate and the second ceramic of the heat generating element include at least one of a metal nitride and a metal oxide, a content of the second ceramic in the heat generating element is greater than a content of the second metal carbide in the heat generating element, the heat generating element has a relative density of 95% or more and a volume resistance value of 1.0 Ω·cm or less at room temperature, and a rate of change of the volume resistance value of the heat generating element with an increase in temperature by 100° C. is 0.1 or less.