Electrostatic Chuck Heater Vias to Prevent Alumina Cracking
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Solution Overview
Problem
Resin sheets in electrostatic chuck heaters lack sufficient heat resistance and heat transfer capability, leading to cracking issues between alumina ceramics and vias due to thermal expansion differences.
Innovation Solution
Incorporating ruthenium metal with a filler component like alumina and zirconia into the heating element and power supply vias, and the electrostatic electrode, resistance heating element, and jumper wire, to minimize thermal expansion differences with the alumina substrate, thereby reducing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the via size is increased to lower resistance and decrease heat generation, then electrical performance is improved, but thermal expansion difference causes cracking
Solution Approach 1:
The patent changes the material composition parameter of the via by incorporating ruthenium metal (10-95 wt%) to match the thermal expansion coefficient of alumina substrate (7.9 ppm/K) within ±0.6 ppm/K. This parameter change allows larger via sizes for better electrical performance without causing cracking due to thermal expansion mismatch.
Solution Approach 2:
The patent uses composite materials in the via structure, combining ruthenium metal with alumina and/or zirconia filler components. This composite approach achieves both low resistance (through high conductivity of ruthenium) and matched thermal expansion (through the ceramic filler), resolving the contradiction between electrical performance and structural integrity.
2Ease of manufacture
If resin sheet is used for bonding, then ease of manufacture is improved, but heat resistance and heat transfer capability are insufficient
Solution Approach 1:
The patent replaces the durable but thermally inadequate resin sheet with a sintered ceramic structure containing embedded metal vias. While sintering is a more complex process, it creates a permanent, heat-resistant bonding structure that eliminates the need for organic adhesives, effectively treating the bonding layer as a structural component rather than a temporary connector.
Solution Approach 2:
The patent changes the material parameter from organic resin to inorganic sintered ceramic, which fundamentally improves heat resistance and thermal conductivity. The sintering process creates direct ceramic-to-ceramic bonding with embedded metal vias, achieving both manufacturability and high-temperature performance.
3Temperature
If alumina ceramic is used for substrate, then heat resistance is improved, but cracking between alumina and vias occurs due to thermal expansion difference
Solution Approach 1:
The patent changes the via material composition to contain ruthenium metal (10-95 wt%) specifically selected because its thermal expansion coefficient (7.2 ppm/K) closely matches alumina (7.9 ppm/K) within ±0.6 ppm/K. This parameter matching prevents cracking while maintaining the heat resistance of the alumina substrate.
Solution Approach 2:
The patent employs composite via material consisting of ruthenium metal combined with alumina and/or zirconia fillers. This composite structure provides both the thermal expansion matching (through ruthenium) and the ceramic compatibility (through alumina/zirconia fillers), preventing cracking at the alumina-via interface while maintaining structural integrity.
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 use of ruthenium metal and filler components reduces thermal expansion differences, minimizing cracking and heat generation, and enhances interfacial strength and resistivity, resulting in a more reliable electrostatic chuck heater.
Implementation Method 1
Each via has a ruthenium metal content in the range of 10% to 95% by weight. Alumina has a thermal expansion coefficient of 7.9 ppm/K in the temperature range of 40° C. to 800° C., and ruthenium metal has a thermal expansion coefficient of 7.2 ppm/K in the temperature range of 40° C. to 800° C. The difference in thermal expansion coefficient between the vias and the alumina substrate is within ±0.6 ppm/K.
Implementation Method 2
a resistance heating element provided for each zone, and a multilayer jumper wire for supplying power to the resistance heating element
Data Source
AI summary
An electrostatic chuck heater according to the present invention includes an alumina substrate having a wafer placement surface on its upper surface; an electrostatic electrode, a resistance heating element provided for each zone, and a multilayer jumper wire for supplying power to the resistance heating element, which are buried in the alumina substrate in this order from the wafer placement surface side; a heating element coupling via for vertically coupling the resistance heating element to the jumper wire; and a power supply via extending outward for supplying power to the jumper wire. At least the heating element coupling via and the power supply via contain ruthenium metal.