Plasma Processing Focus Ring Cover Ring Spacing Design
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Solution Overview
Problem
The consumption of a quartz cover ring in plasma processing apparatuses leads to area variations and process variations, such as substrate tilting, due to the exposure of the focus ring's outer peripheral side surface as the cover ring is consumed, causing discontinuity in bias potential and non-uniform plasma processing.
Innovation Solution
A plasma processing apparatus design featuring a conductive focus ring surrounded by a dielectric cover ring with a conductive ring placed on top, where the cover ring has a spacing portion to separate the focus ring from the conductive ring, and a radio frequency power supply is electrically coupled to the substrate support, ensuring the focus ring functions as a cathode while the conductive ring remains electrically floating, reducing ion acceleration and sputtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quartz cover ring is used to cover the focus ring, then the focus ring is protected from plasma exposure, but the cover ring is consumed by sputtering over time causing area variation and process instability
Solution Approach 1:
A dielectric ring is introduced as an intermediary component between the focus ring and the plasma environment. This dielectric ring absorbs the sputtering damage that would otherwise affect the focus ring, serving as a sacrificial protective layer that maintains the focus ring's area and electrical characteristics stable over time.
Solution Approach 2:
The invention changes the material parameter of the protective ring from conductive (original focus ring material) to dielectric. This parameter change allows the protective ring to function differently - it can be consumed by sputtering without affecting the electrical bias potential distribution, since the dielectric material does not conduct electricity like the original focus ring material did.
2Manufacturing precision
If the cover ring is consumed and the focus ring's outer peripheral side surface is exposed, then area variation of the focus ring occurs, but this causes discontinuity in bias potential and non-uniform plasma processing
Solution Approach 1:
The dielectric ring acts as a mediator that maintains a consistent gap between the plasma environment and the focus ring. By consuming uniformly through sputtering, it preserves the focus ring's geometric integrity and electrical characteristics, preventing the area variation and bias potential discontinuity that would occur if the focus ring were directly exposed.
Solution Approach 2:
The dielectric ring provides beforehand cushioning by being positioned between the plasma and the focus ring. It absorbs the harmful sputtering effects in advance, protecting the focus ring from direct plasma exposure and the associated area variation and electrical instability problems.
3Duration of action of stationary object
If a conductive cover ring is used, then the focus ring is protected, but the conductive ring itself is consumed by sputtering requiring frequent replacement
Solution Approach 1:
The invention changes the electrical parameter of the protective ring from conductive to dielectric. This parameter change fundamentally alters how the ring interacts with plasma - dielectric materials can withstand sputtering better and maintain their protective function longer without the same degree of material loss and degradation that conductive materials experience.
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 suppresses the sputtering of the conductive ring and focus ring, maintaining uniform plasma processing and preventing substrate tilting by adjusting the potential and reducing ion acceleration, thereby stabilizing the plasma processing environment.
Implementation Method 1
a radio frequency power supply configured to supply radio frequency power to the substrate support
Implementation Method 2
a plasma processing apparatus for performing substrate processing
Implementation Method 3
the cover ring made of quartz that covers the outer peripheral side surface of the focus ring may be consumed as time elapses due to a sputtering of ions of plasma
Data Source
AI summary
A plasma processing apparatus includes a substrate support having a substrate supporting portion on which a substrate is placed and a peripheral portion surrounding the substrate supporting portion, a conductive focus ring placed on the peripheral portion of the substrate support, a cover ring surrounding an outer periphery of the substrate support and formed of a dielectric material, a conductive ring placed on the cover ring, and a radio frequency power supply electrically coupled to the substrate support. A first surface on an outer peripheral portion of the focus ring and a second surface on an inner peripheral portion of the conductive ring are spaced apart from each other while facing each other. Further, the cover ring has a spacing portion that separates the focus ring from the conductive ring.