Electrostatic Chuck with Layered Resistivity for Wafer Detachment
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Solution Overview
Problem
Ceramic electrostatic chucks with high volume resistivity support layers and dielectric layers face issues such as long detachment times, warping during manufacturing, and mechanical strength deterioration after temperature cycling, which affect processing speed and reliability.
Innovation Solution
A ceramic electrostatic chuck with a dielectric layer made of sintered aluminum nitride containing Sm and a support layer made of sintered aluminum nitride containing Sm and Ce, achieving a high attractive force, short detachment time, and reduced mechanical strength deterioration, with a molybdenum metal or alloy electrode for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a support layer with high volume resistivity is used, then stable attractive force is achieved, but detachment time becomes long
Solution Approach 1:
The patent applies different volume resistivity characteristics to different layers: the dielectric layer has volume resistivity of 10^8 to 10^13 Ωcm for stable attractive force, while the support layer has higher volume resistivity (10^14 to 10^16 Ωcm) to enable rapid charge dissipation and short detachment time. This local differentiation resolves the contradiction between maintaining attractive force and achieving quick detachment.
2Shape
If a thin support layer is used, then warping during manufacture is reduced, but manufacturing precision becomes difficult to maintain
Solution Approach 1:
The patent uses a composite structure of dielectric layer and support layer with different material properties. The support layer has higher volume resistivity and different thermal expansion characteristics that compensate for warping tendencies, allowing thin layers to maintain both reduced warping and manufacturing precision through material composition rather than thickness alone.
3Productivity
If temperature cycling is performed, then processing efficiency is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent selects specific volume resistivity ranges for each layer that remain stable across temperature cycles. The dielectric layer (10^8 to 10^13 Ωcm) and support layer (10^14 to 10^16 Ωcm) are formulated to maintain their electrical and mechanical properties through thermal expansion and contraction, preventing bonding strength deterioration while enabling temperature-cycled processing.
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 electrostatic chuck exhibits a high attractive force, reduced warping, and maintained mechanical strength after heat cycles, ensuring efficient processing and reliability.
Implementation Method 1
Electrostatic chucks that include a dielectric layer having a volume resistivity in the range of approximately 108 to 1013 Ωcm are known as Johnsen-Rahbek-type electrostatic chucks
Implementation Method 2
a support layer that is in contact with the back side of the dielectric layer, is formed of sintered aluminum nitride containing Sm and Ce, and has a volume resistivity of 1×1013 Ωcm or more at room temperature
Data Source
AI summary
A ceramic electrostatic chuck according to the present invention includes a dielectric layer with a support layer in contact with the back side of the dielectric layer, and an embedded electrostatic electrode. A wafer is placed on the dielectric layer and the dielectric layer is formed of sintered aluminum nitride containing Sm and has a volume resistivity in the range of 4×109 to 4×1010 Ωcm at room temperature. The support layer is formed of sintered aluminum nitride containing Sm and Ce and has a volume resistivity of 1×1013 Ωcm or more at room temperature.