Electrostatic Chuck Porous Electrode Stress Reduction
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Solution Overview
Problem
Conventional electrostatic chucks face limitations in plasma controllability and electrical resistance issues when using high-frequency power for plasma generation, particularly due to internal stress and increased electrical resistance in thick dielectric layers with high porosity.
Innovation Solution
An electrostatic chuck design featuring a ceramic dielectric substrate with a first electrode layer connected to a high-frequency power supply, where the porosity is strategically varied to reduce internal stress and electrical resistance, and the electrode configuration is optimized to enhance plasma density uniformity and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the lower electrode for plasma generation is increased to accommodate higher frequencies, then the plasma density can be increased, but the internal stress of the electrode increases
Solution Approach 1:
The patent applies porous materials by forming the lower electrode as a porous body with controlled porosity (30-70%). This porous structure reduces the internal stress that would otherwise accumulate in a thick solid electrode, while still maintaining sufficient electrical conductivity for plasma generation at high frequencies. The porosity allows stress relief without compromising the electrode's primary function.
Solution Approach 2:
The patent employs composite materials by creating a lower electrode that combines conductive material (such as metal particles or conductive ceramic) with a porous matrix structure. This composite approach enables the electrode to simultaneously achieve high frequency response, adequate electrical conductivity, and reduced internal stress through the porous architecture.
2Stress or pressure
If the porosity of the electrode is increased to relax internal stress, then the internal stress is reduced, but the electrical resistance increases
Solution Approach 1:
The patent resolves this contradiction by using composite materials where conductive particles or phases are distributed within a porous matrix. The conductive network maintains low electrical resistance even with high porosity (30-70%), while the porous structure provides stress relief. This composite structure allows simultaneous optimization of both stress resistance and electrical conductivity.
Solution Approach 2:
The patent applies local quality by creating regions with different porosity levels or conductive material concentrations within the electrode. Areas requiring high conductivity maintain lower porosity or higher conductive material content, while other regions can have higher porosity for stress relief, optimizing both properties locally throughout the electrode structure.
3Stress or pressure
If the porosity of the electrode is increased to relax internal stress, then the internal stress is reduced, but the plasma controllability deteriorates
Solution Approach 1:
The patent uses composite materials to maintain the electrode's ability to respond to RF power while reducing stress through porosity. The conductive network within the porous structure ensures good plasma controllability by maintaining adequate electrical conductivity, while the porous framework provides stress relief. This allows the electrode to effectively control plasma density and distribution.
Solution Approach 2:
The patent applies parameter changes by optimizing the porosity to a specific range (30-70%) rather than using extreme values. This intermediate porosity level balances stress relief with maintained electrical conductivity and plasma controllability, representing an optimized parameter setting that satisfies multiple competing requirements.
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 solution effectively increases plasma density and uniformity while reducing electrical resistance and internal stress, allowing for more efficient plasma processing with lower power consumption and improved responsiveness to RF control.
Implementation Method 1
plasma is generated by applying a voltage from an RF (Radio Frequency) power supply (a high frequency power supply) to an upper electrode provided at an upper portion inside a chamber and to a lower electrode provided lower than the upper electrode
Implementation Method 2
The electrostatic chuck applies electrical power for electrostatic attraction to a built-in electrode and attracts and holds a substrate such as a silicon wafer, etc., by an electrostatic force
Implementation Method 3
when an alternating current flows through an electrode, a phenomenon called skin effect occurs in which the current density is high at the electrode surface and decreases away from the surface
Data Source
AI summary
According to one embodiment, an electrostatic chuck includes a ceramic dielectric substrate, a base plate, and a first electrode layer. The ceramic dielectric substrate has a first major surface and a second major surface. The first electrode layer is provided inside the ceramic dielectric substrate and connected to a high frequency power supply. The first electrode layer is provided between the first major surface and the second major surface. The first electrode layer has a first surface and a second surface. The first electrode layer includes a first region including the first surface, a second region including the second surface, and a third region positioned between the first region and the second region. A porosity of the first region is lower than a porosity of the third region.