Electrostatic Chuck With Embedded Electrode Thickness Variation
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Solution Overview
Problem
Conventional electrostatic chucks have limited plasma controllability and in-plane uniformity of plasma density, especially when using a base plate as the lower electrode for plasma generation.
Innovation Solution
An electrostatic chuck design featuring a ceramic dielectric substrate with a first electrode layer and a second electrode layer, where the first electrode layer is positioned between the substrate's surfaces and connected to a high-frequency power supply, and the second electrode layer is connected to a clamping power supply, with specific thickness variations and positioning to optimize electric field distribution and plasma density uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a base plate is used as the lower electrode for plasma generation, then the electrostatic chuck structure is simple, but the plasma controllability and in-plane uniformity of plasma density are limited
Solution Approach 1:
The lower electrode is segmented into multiple independent electrode layers (first electrode layer connected to RF power supply, second electrode layer connected to clamping power supply) embedded within the dielectric layer, allowing independent control of plasma generation and substrate clamping functions
Solution Approach 2:
The first electrode layer is designed with non-uniform thickness (thicker at center, thinner at edges) to create localized electric field distribution that compensates for natural plasma density variations, achieving uniform plasma density across the substrate surface
2Device complexity
If a base plate is used as the lower electrode, then the structure is simple, but the in-plane uniformity of plasma density cannot be sufficiently obtained
Solution Approach 1:
The first electrode layer employs varying thickness (thicker at center portion, thinner at edge portion) to create non-uniform electric field distribution that compensates for natural plasma density gradients, achieving uniform plasma density across the substrate surface
Solution Approach 2:
The electrode design transitions from a two-dimensional planar base plate to a three-dimensional multi-layer embedded structure within the dielectric layer, enabling control of plasma density distribution through vertical layering and thickness variation
3Manufacturing precision
If the second portion thickness varies with less thickness at circumferential end, then plasma density uniformity is improved, but manufacturing complexity increases
Solution Approach 1:
The thickness parameter of the second portion is intentionally varied (thicker at center, thinner at edges) to optimize plasma density uniformity, transforming a geometric parameter to achieve functional improvement
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 enhances plasma controllability and in-plane uniformity of plasma density, reduces the need for high electrical power, and improves heat dissipation and responsiveness to RF output modifications.
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
plasma is generated by applying a voltage from an RF (Radio Frequency) power supply (a high frequency power supply)
Implementation Method 3
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
Data Source
AI summary
According to one embodiment, an electrostatic chuck includes a ceramic dielectric substrate, a base plate, and first and second electrode layers. The ceramic dielectric substrate includes first and second major surfaces. The first and second electrode layers are provided inside the ceramic dielectric substrate. The first electrode layer includes first and second portions. The first portion is positioned more centrally of the ceramic dielectric substrate than is the second portion. The first portion includes first and second surfaces. The second portion includes third and fourth surfaces. A distance between the third surface and the first major surface is constant. A thickness of the second portion between the third and fourth surfaces varies such that the thickness at a circumferential end portion of the second portion which is less than that at a central portion of the second portion.