Electrostatic Chuck Lower Plate Composition for Thermal Expansion Matching
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Solution Overview
Problem
Existing electrostatic chucks (ESCs) face issues due to mismatched thermal expansion coefficients between their ceramic and aluminum components, leading to structural failures, reduced yield, and increased maintenance costs in semiconductor manufacturing processes.
Innovation Solution
The ESC is constructed with a lower plate made by sintering a mixture of aluminum and other materials like stainless steel, titanium, or magnesium, combined with silicon-carbide, silicon nitride, diamond, carbon nanotubes, or graphene, to match the thermal expansion coefficient of the ceramic upper plate, using a specific powder ratio and sintering conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a common ESC structure with ceramic upper plate and aluminum lower plate is used, then heat transfer to the wafer is facilitated, but the different coefficients of thermal expansion cause the plates to separate and adhesive to tear under severe temperature changes
Solution Approach 1:
The patent changes the material composition parameters of the lower plate by incorporating ceramic particles (alumina, silica, magnesia) into the aluminum alloy, thereby adjusting the coefficient of thermal expansion to match the upper plate while maintaining heat transfer capability
Solution Approach 2:
The patent creates a composite material for the lower plate by combining aluminum alloy with ceramic particles (alumina, silica, magnesia), achieving both thermal expansion compatibility and effective heat transfer through the composite structure
2Temperature
If the upper plate is made of thin ceramic to facilitate heat transfer, then thermal conductivity is improved, but the plate becomes more susceptible to breaking under thermal stress
Solution Approach 1:
The patent adjusts the thermal expansion parameters of the lower plate to match the ceramic upper plate, reducing thermal stress differential and preventing upper plate breakage during temperature cycling
3Temperature
If aluminum is used as the lower plate material for heat transfer, then thermal conductivity is improved, but the coefficient of thermal expansion mismatch with ceramic causes structural failure
Solution Approach 1:
The patent develops a composite lower plate material combining aluminum alloy with ceramic particles (alumina, silica, magnesia) in specific proportions, achieving both thermal conductivity and thermal expansion compatibility with the ceramic upper plate
Solution Approach 2:
The patent modifies the thermal expansion characteristics of the lower plate by incorporating ceramic particles with controlled size distributions (0.1-10 μm, 10-50 μm, 50-100 μm), tuning the composite's coefficient of thermal expansion to match the upper plate
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 extends the ESC's lifespan, reduces maintenance time, and prevents wafer yield loss by minimizing thermal expansion-related damage, enhancing productivity in semiconductor production.
Implementation Method 1
the lower plate is sintered and molded at a high temperature under vacuum and pressurization by mixing first powder including at least one of aluminum, stainless steel (SUS), titanium, and magnesium
Implementation Method 2
The ESC means a chuck type in which a wafer can be fixed to a chuck by an electrostatic force that is generated by applying a static voltage to the chuck
Data Source
AI summary
The present disclosure relates to an electrostatic chuck and a method of manufacturing the same. A problem in that the yield of a wafer is reduced due to a partial destruction phenomenon attributable to thermal expansion of an electrostatic chuck is solved and the lifespan of a wafer is increased by making a coefficient of thermal expansion of a lower plate of an electrostatic chuck similar to a coefficient of thermal expansion of an upper plate of the electrostatic chuck.