Electrostatic Chuck Electrode Thickness Variation for Plasma Uniformity
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Solution Overview
Problem
Conventional electrostatic chucks face limitations in plasma controllability and in-plane uniformity of plasma density, with issues of electric field concentration and dielectric breakdown at the end portions of embedded electrodes.
Innovation Solution
The electrostatic chuck design includes a ceramic dielectric substrate with a first electrode layer positioned centrally and a second electrode layer at the circumference, where the thickness varies from the central portion to the circumferential end portion, maintaining a constant distance between the electrode surfaces to reduce electric field concentration and enhance plasma controllability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the lower electrode is merely embedded in the dielectric layer, then the device complexity is reduced, but the in-plane uniformity of plasma density cannot be sufficiently obtained and electric field concentration occurs
Solution Approach 1:
The first electrode layer is designed with different thicknesses in different regions: a first thickness in the central region and a second thickness in the peripheral region, where the second thickness is greater than the first thickness. This local quality variation ensures uniform electric field distribution and plasma density across the substrate surface, resolving the contradiction between simplified structure and manufacturing precision.
2Ease of manufacture
If the electrode thickness is uniform throughout, then the manufacturing process is simplified, but electric field concentration and dielectric breakdown occur at end portions
Solution Approach 1:
The electrode structure transitions from uniform thickness to variable thickness, with the first electrode layer having a first thickness at the center and a greater second thickness at the periphery. This local variation prevents electric field concentration at the edges, thereby preventing dielectric breakdown while maintaining manufacturing feasibility through controlled deposition or lamination processes.
3Device complexity
If a single electrode layer is used, then the device structure is simplified, but plasma controllability is limited
Solution Approach 1:
The electrode system is segmented into a first electrode layer with different thickness regions (central and peripheral portions) that can be independently controlled. This segmentation enables differentiated plasma generation and control across different zones of the substrate, enhancing plasma controllability while maintaining a relatively simple overall structure compared to multiple separate electrode layers.
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 improves plasma controllability and in-plane uniformity of plasma density while preventing dielectric breakdown, allowing for more effective heat dissipation and increased responsiveness to RF power 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
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 fourth 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.