Electrostatic Chuck Electrode Metal Concentration Gradient
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Solution Overview
Problem
Conventional electrostatic chucks have limited plasma controllability and in-plane uniformity of plasma density, particularly when attempting to control plasma distribution during semiconductor processing, due to the configuration of the lower electrode.
Innovation Solution
An electrostatic chuck with a ceramic dielectric substrate and a first electrode layer connected to a high-frequency power supply, where the first electrode layer includes a higher concentration of metal component in specific portions to enhance the skin effect and reduce electrical resistance, allowing for improved plasma controllability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a base plate is used as the lower electrode for plasma generation, then the 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, second electrode layer, third electrode layer) with different functions. The first electrode layer is for plasma generation connected to RF power supply, the second electrode layer is for chucking connected to DC power supply, and the third electrode layer is for temperature control. This segmentation allows independent control of plasma generation, substrate holding, and thermal management, thereby improving plasma controllability while maintaining structural organization.
Solution Approach 2:
Multiple electrode layers are nested within the dielectric layer, with each electrode layer positioned at different depths. The first electrode layer is positioned closest to the plasma generation region, the second electrode layer is positioned deeper for chucking function, and the third electrode layer is positioned deepest for temperature control. This nested arrangement allows multiple functions to be integrated within a compact structure, improving plasma controllability without excessive complexity.
2Reliability
If the first electrode layer has high metal component concentration throughout, then electrical resistance is reduced, but the skin effect is weakened
Solution Approach 1:
The first electrode layer exhibits non-uniform metal component concentration distribution. The metal component concentration is higher near the plasma generation surface (first surface) to enhance the skin effect and improve plasma density control, and lower near the base plate interface (second surface) to reduce electrical resistance. This local quality variation allows simultaneous optimization of both skin effect and electrical resistance characteristics.
Solution Approach 2:
The metal component concentration parameter is varied continuously or stepwise through the thickness of the first electrode layer. By changing the concentration parameter from high near the plasma surface to low near the base plate, the patent achieves optimal balance between skin effect enhancement (requiring high surface concentration) and electrical resistance reduction (benefiting from low bulk concentration).
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 increases plasma density and controllability, and enhances the in-plane uniformity of the plasma density by promoting the skin effect and reducing electrical resistance, thereby improving the efficiency of plasma processing.
Implementation Method 1
a concentration of the metal component in the first portion is higher than an average concentration of the metal component in the first electrode layer... promoting the skin effect
Implementation Method 2
The electrostatic chuck applies electrical power for electrostatic attraction to a built-in electrode and chucks a substrate such as a silicon wafer, etc., by an electrostatic force
Implementation Method 3
plasma is generated by applying a voltage from an RF (Radio 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
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 first and second major surfaces. The first electrode layer is provided inside the ceramic dielectric substrate. The first electrode layer is connected to a high frequency power supply. The first electrode layer has a first surface at the first major surface side and a second surface at a side opposite to the first surface. The first electrode layer includes a first portion including the first surface. The first electrode layer includes a ceramic component and a metal component. A concentration of the metal component in the first portion is higher than an average concentration of the metal component in the first electrode layer.