Adjustable Edge Ring Structure for Plasma Sheath Uniformity
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Solution Overview
Problem
In plasma processing apparatuses, the consumption of parts such as focus rings affects the uniformity of plasma processing due to changes in the height of the plasma sheath, leading to process changes in the central and intermediate regions of the wafer.
Innovation Solution
A plasma processing apparatus is designed with a substrate support that includes an electrostatic chuck and a multi-layered edge ring system. The edge ring system consists of a first ring with varying annular portions and a second ring that can be vertically adjusted by an actuator to maintain a specific height, thereby controlling the impedance and maintaining uniform plasma processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focus ring is raised by an elevating mechanism to compensate for consumption, then the height of the plasma sheath above the focus ring is maintained, but the impedance changes causing process changes in the central and intermediate regions of the wafer
Solution Approach 1:
The focus ring is divided into multiple annular portions (inner, intermediate, outer) with different heights. The intermediate annular portion is positioned at a lower height than the inner and outer portions, creating a stepped structure that differentially affects plasma sheath height in different radial regions of the wafer
Solution Approach 2:
Different portions of the focus ring are given different heights to address local variations in plasma sheath height. The intermediate annular portion is specifically lowered to compensate for excessive plasma sheath height in the central region, while the inner and outer portions maintain higher heights for their respective regions
2Manufacturing precision
If the focus ring height is increased to maintain plasma sheath height, then edge region plasma uniformity is improved, but tilting control at the end portion of the substrate is compromised
Solution Approach 1:
The focus ring structure is made adjustable through the elevating mechanism, allowing dynamic adjustment of the inner and outer annular portions relative to the intermediate portion. This enables the system to adapt to different processing conditions and maintain both plasma sheath height and tilting control
3Device complexity
If a simple elevating mechanism is used to raise the focus ring, then the structure is simple, but it cannot suppress process changes in the central and intermediate regions while controlling tilting
Solution Approach 1:
The focus ring is segmented into multiple annular portions with different heights, allowing differential adjustment of plasma sheath height in different radial regions. This segmentation enables precise control of plasma processing uniformity without requiring complex multi-component systems
Solution Approach 2:
The multi-annular focus ring structure simultaneously achieves multiple functions: maintaining plasma sheath height in edge regions, suppressing process changes in central and intermediate regions, and controlling tilting at the substrate end portion, all through a single integrated component
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 configuration effectively suppresses process changes in the central and intermediate regions of the substrate while allowing control of tilting at the end portion of the substrate, ensuring consistent and uniform plasma processing.
Implementation Method 1
an actuator configured to vertically move the second ring so as to maintain a top surface of the second ring at a first height
Implementation Method 2
a substrate support disposed in the plasma processing chamber, the substrate support including an electrostatic chuck
Implementation Method 3
A plasma processing apparatus performs a plasma processing, such as etching, on a target object, such as a semiconductor wafer
Data Source
AI summary
A plasma processing apparatus includes a plasma processing chamber; a substrate support disposed in the plasma processing chamber and including an electrostatic chuck; a first ring disposed on the electrostatic chuck to surround a substrate on the electrostatic chuck and including an inner annular portion, an intermediate annular portion, and an outer annular portion, a top surface of the inner annular portion being higher than that of the intermediate annular portion, a top surface of the outer annular portion being higher than that of the inner annular portion; a second ring disposed on the intermediate annular portion; and an actuator configured to vertically move the second ring to maintain a top surface of the second ring at a first height greater than a height of the top surface of the inner annular portion and less than a height of the top surface of the outer annular portion.