Plasma Processing Sheath Adjuster for Focus Ring Wear Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In plasma etching processes, the wear down of focus rings leads to a reduction in their thickness, causing the upper end of the plasma sheath to lower, resulting in an uneven etching rate between the edge and the inside of the substrate, as the position of the sheath on the focus ring becomes misaligned with that on the substrate.
Innovation Solution
A plasma processing apparatus is designed with a sheath adjuster and variable impedance circuits to adjust the position of the upper end of the sheath on the focus ring and control the power distribution, using a power source to apply a negative voltage to the focus ring and incorporating sensors and controllers to set predetermined impedance levels, ensuring uniform etching rates across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the focus ring is used during plasma etching, then the etching process can be performed, but the focus ring wears down and its thickness is reduced, causing the sheath position to lower and etching uniformity to deteriorate
Solution Approach 1:
The focus ring is made movable in the vertical direction through a driving mechanism (such as a screw mechanism or motor) that can adjust its position dynamically. This allows the focus ring to be moved upward to compensate for wear, maintaining the sheath position and etching uniformity throughout the focus ring's service life
Solution Approach 2:
The vertical position of the focus ring is changed as a parameter to compensate for wear. By adjusting the focus ring's position (changing its vertical coordinate), the system maintains the optimal sheath position despite the focus ring's thickness reduction over time
2Duration of action of stationary object
If the focus ring thickness is reduced due to wear, then the focus ring continues to be usable, but the upper end position of the sheath on the focus ring is lowered, causing misalignment with the substrate sheath position
Solution Approach 1:
The focus ring's vertical position is made dynamic rather than fixed. A driving mechanism allows the focus ring to be moved vertically to compensate for wear, ensuring that the sheath position remains aligned with the substrate throughout the focus ring's extended service life
Solution Approach 2:
A detection mechanism (such as a sensor or gauge) monitors the focus ring's thickness or vertical position and provides feedback to a control system. Based on this feedback, the driving mechanism automatically or manually adjusts the focus ring's position to maintain proper sheath alignment
3Device complexity
If a fixed focus ring is used, then the structure is simple, but the sheath position cannot be adjusted when the focus ring wears down, leading to poor etching uniformity
Solution Approach 1:
The focus ring structure is changed from fixed to movable by adding a simple driving mechanism (such as a screw, motor, or actuator). This minimal addition enables vertical adjustment to compensate for wear while maintaining overall structural simplicity
Solution Approach 2:
The system includes automatic detection and adjustment mechanisms that allow the focus ring position to be self-corrected based on wear detection, reducing the need for manual intervention and maintaining etching uniformity automatically
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 solution effectively adjusts the sheath position and power distribution, reducing the difference in etching rates between the edge and the inside of the substrate, thereby improving the uniformity and efficiency of the plasma etching process.
Implementation Method 1
The sheath adjuster is configured to adjust a position in a vertical direction of an upper end of a sheath on/above the focus ring
Implementation Method 2
The variable impedance circuit is provided on the first electrical path or the second electrical path
Implementation Method 3
radio frequency power is supplied to the lower electrode. Plasma is formed from the gas in the chamber
Data Source
AI summary
A substrate support is provided in a chamber of a plasma processing apparatus according to an exemplary embodiment. The substrate support has a lower electrode and an electrostatic chuck. A matching circuit is connected between a power source and the lower electrode. A first electrical path connects the matching circuit and the lower electrode to each other. A second electrical path different from the lower electrode is provided to supply electric power from the matching circuit to a focus ring. A sheath adjuster is configured to adjust a position of an upper end of a sheath on/above the focus ring. A variable impedance circuit is provided on the first or second electrical path.