Plasma Bias Electrode Control for Edge Ring Sheath Stability
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in controlling the potential of multiple bias RF signals with different frequencies, leading to issues such as tilting of etching holes due to variations in plasma sheath thickness and direction of the electric field, especially when the edge ring is consumed.
Innovation Solution
The apparatus incorporates a substrate supporter with a first and second bias electrode, an impedance adjustment mechanism, and an electrical path, including parallel-connected impedance adjustment mechanisms and an isolator to control different frequency bias signals, allowing independent control of the potential on the edge ring side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bias power source is used to supply bias signals to both the substrate and edge ring, then the device complexity is reduced, but the controllability of multiple bias RF signals with different frequencies deteriorates
Solution Approach 1:
The patent divides the single bias power source into multiple independent bias power sources (first bias power source and second bias power source), each capable of independently controlling bias signals at different frequencies. This segmentation enables separate control of substrate and edge ring bias signals, resolving the contradiction between device simplicity and controllability.
2Measurement precision
If impedance adjustment mechanisms are connected in series to control different frequencies, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple impedance adjustment mechanisms in parallel connection to a common impedance adjustment electrode, rather than connecting them in series. This merging approach maintains control precision for different frequencies while reducing the overall complexity of the impedance adjustment system.
3Device complexity
If the edge ring is allowed to erode naturally, then the device maintenance complexity is reduced, but the manufacturing precision deteriorates due to plasma sheath height variation
Solution Approach 1:
The patent implements an impedance adjustment mechanism that monitors and adjusts the impedance of the edge ring bias signal in real-time. This feedback control compensates for edge ring erosion effects, maintaining consistent plasma sheath height and etching precision without requiring frequent manual maintenance or replacement of the edge ring.
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 improves the controllability of multiple bias RF signals with different frequencies, maintaining a consistent plasma sheath height and reducing tilting, thereby enhancing the precision and efficiency of plasma processing.
Implementation Method 1
an isolator connected between the impedance adjustment electrode and the first impedance adjustment mechanism and blocking the second bias signal
Implementation Method 2
a first bias power source configured to supply a first bias signal; a second bias power source configured to supply a second bias signal
Implementation Method 3
a plasma sheath is lowered adjacent to an edge ring due to erosion of the edge ring
Data Source
AI summary
A plasma processing apparatus comprises: a chamber; first and second bias power sources for supplying first and second bias signals; a substrate supporter for supporting a substrate and an edge ring, inside the chamber; an impedance adjustment mechanism; and an electrical path. The substrate supporter includes: first and second regions supporting the substrate and the edge ring, first and second bias electrodes in the first and second regions, and an impedance adjustment electrode provided in the second region and grounded. The impedance adjustment mechanism includes: a first impedance adjustment mechanism controlling the first bias signal. An isolator and the first impedance adjustment mechanism, and the second impedance adjustment mechanism are connected in parallel, and are connected to the impedance adjustment electrode. The electrical path is configured to connect the first bias power source and the second bias power source, to the first bias electrode and the second bias electrode.