Plasma Etching Edge Polymer Deposition for Focus Ring Life
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Solution Overview
Problem
In semiconductor etching, the focus ring is damaged by etching gas over time, leading to non-uniform gas distribution on the wafer, especially at the edges, causing inefficiencies and the need for frequent replacement, which reduces throughput and increases waste due to the discontinuity of the topography.
Innovation Solution
An annular conduit with holes is positioned above the edge of a nitride layer on the wafer, spraying an unsaturated fluorocarbon gas, such as hexafluorobutadiene, to the edge portion, where it polymerizes and forms a protective layer, reducing the etching rate and maintaining uniformity by adjusting the flow rate over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the focus ring is used to hold the wafer in the center of the electrostatic chuck, then the etching gas distribution is uniform on the wafer, but the focus ring is damaged by etching gas over time leading to non-uniform gas distribution
Solution Approach 1:
The patent applies local quality by spraying unsaturated fluorocarbon specifically to the edge portion of the nitride layer where the focus ring contacts the wafer. This localized treatment creates a protective polymer coating exactly where the damage occurs, rather than treating the entire wafer surface uniformly. The annular conduit is positioned to target only the peripheral region, addressing the specific problem area while maintaining etching uniformity elsewhere.
Solution Approach 2:
The patent converts the harmful effect of etching gas on the focus ring into a beneficial protective mechanism. By introducing unsaturated fluorocarbon that polymerizes under plasma conditions, the harmful etching environment is transformed into a condition that deposits protective polymer material on the edge portion, thereby protecting the focus ring from damage while utilizing the existing plasma environment.
2Manufacturing precision
If the focus ring is replaced frequently due to damage, then the etching uniformity is maintained, but the throughput decreases and waste increases
Solution Approach 1:
The patent implements preliminary action by depositing the protective polymer coating on the edge portion before significant damage occurs to the focus ring. The unsaturated fluorocarbon is continuously sprayed and polymerized in advance, creating a protective barrier that prevents future damage. This proactive approach extends focus ring life and maintains throughput by avoiding frequent replacements.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining continuous spraying of unsaturated fluorocarbon during the etching process. This continuous protective coating formation ensures the focus ring remains protected throughout operation, maintaining both etching uniformity and throughput without interruption for replacement.
3Manufacturing precision
If the unsaturated fluorocarbon is sprayed to the edge portion, then the non-uniform etching is prevented, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the gas distribution system into two functional parts: the main plasma source for bulk etching and the annular conduit for targeted edge portion treatment. This segmentation allows independent control of the protective coating deposition, enabling precise application to only where needed without affecting the overall etching process.
Solution Approach 2:
The patent introduces unsaturated fluorocarbon as an intermediary substance that mediates between the plasma environment and the focus ring. This intermediary material polymerizes to form a protective layer, acting as a buffer that protects the focus ring from direct exposure to harsh etching conditions while maintaining process control.
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 method prevents non-uniform etching at the wafer edges, prolongs the life of the focus ring, and enhances etching throughput by maintaining consistent etching rates across the wafer, reducing the need for frequent part replacements and waste.
Implementation Method 1
A plasma is sprayed onto an upper surface of the nitride layer
Implementation Method 2
polymerizing the unsaturated fluorocarbon to form a polymer on the edge portion of the nitride layer, in which the polymerizing the unsaturated fluorocarbon is induced by the plasma
Data Source
AI summary
The present disclosure provides a method of plasma etching including the following operations. A wafer and a nitride layer disposed on the wafer are received. An annular conduit is disposed above an edge portion of the nitride layer, in which the annular conduit has a plurality of holes facing the edge portion of the nitride layer. A plasma is sprayed onto an upper surface of the nitride layer. An unsaturated fluorocarbon is sprayed from the holes of the annular conduit to the edge portion of the nitride layer.