Edge Ring Electrical Sensing for Plasma Sheath Position Control
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Solution Overview
Problem
The edge ring in plasma processing apparatuses wears down, causing a sheath to form at a lower position, leading to tilting of recesses in the substrate due to diagonally striking ions, which existing methods fail to effectively address.
Innovation Solution
A plasma processing apparatus with a measuring device that measures electrical characteristic values of the edge ring, allowing for determination of its thickness and adjustment of the sheath position to prevent tilting, using a capacitively coupled electric path and voltage application to the edge ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a DC voltage is applied to the edge ring to reduce tilting of recesses, then the tilting problem is addressed, but the method fails to effectively prevent tilting when the edge ring becomes thin due to wear
Solution Approach 1:
The patent replaces the mechanical/electrical DC voltage adjustment method with an optical measurement system. A laser beam is directed at the edge ring, and the reflected light position is detected to precisely measure the edge ring's thickness and position. This optical substitution allows for accurate detection of edge ring wear without relying on ineffective electrical adjustments.
Solution Approach 2:
The patent introduces a laser beam as an intermediary between the measurement system and the edge ring. The laser serves as a non-contact probe that interacts with the edge ring surface, allowing precise thickness measurement through light reflection patterns without physically touching or electrically influencing the worn edge ring.
2Duration of action of stationary object
If the edge ring thickness decreases due to plasma processing wear, then the sheath position lowers, but this causes ions to diagonally strike the substrate edge creating tilting
Solution Approach 1:
The patent implements preliminary measurement and detection of edge ring thickness before significant wear occurs. By continuously monitoring the edge ring condition using laser reflection patterns, the system can detect thinning trends early and trigger maintenance or replacement actions before the edge ring becomes too thin to maintain proper sheath position and prevent substrate tilting.
Solution Approach 2:
The patent establishes a feedback loop where the laser measurement system continuously monitors edge ring thickness and provides real-time information about wear progression. This feedback enables proactive management of the edge ring, allowing operators to adjust processing parameters or replace the edge ring before it reaches a critical thickness that would cause sheath position degradation and substrate tilting.
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
Enables precise determination of edge ring thickness and adjustment of the sheath position, reducing tilting of recesses in the substrate and improving plasma processing accuracy.
Implementation Method 1
The electric path is coupled to or capacitively coupled to an edge ring on the substrate support. The measuring device measures an electrical characteristic value of the edge ring with a voltage applied to the edge ring on the substrate support through the electric path.
Implementation Method 2
The electric path is coupled to or capacitively coupled to an edge ring on the substrate support.
Implementation Method 3
A plasma processing apparatus is used to perform plasma processing on a substrate. In a chamber in the plasma processing apparatus, the substrate is placed in an area surrounded by an edge ring.
Implementation Method 4
ions in the plasma can diagonally strike the edge of the substrate
Data Source
AI summary
A disclosed plasma processing apparatus includes a chamber, a substrate support, an electric path, and a measuring device. The substrate support is accommodated in the chamber. The electric path is coupled to or capacitively coupled to an edge ring on the substrate support. The measuring device measures an electrical characteristic value of the edge ring with a voltage applied to the edge ring on the substrate support through the electric path. The electrical characteristic value measured by the measuring device is variable in accordance with a thickness of the edge ring.