Grounded Conductive Ring Stabilizes Plasma Etching
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Solution Overview
Problem
In plasma etching processes, the wear-out of edge and cover rings over time leads to fluctuations in etching rates near the substrate edge due to changes in electrostatic capacity and RF signal direction, affecting process consistency and efficiency.
Innovation Solution
Incorporating a second conductive ring connected to ground potential around the cover ring to stabilize the RF current flow and reduce wear-out, thereby maintaining etching rate consistency and confining plasma within the processing space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single conductive ring is used to control etching rate near the substrate edge, then the etching rate can be maintained at the edge, but the ring wears out over time causing fluctuations in etching rate and process inconsistency
Solution Approach 1:
The single conductive ring is divided into multiple separate conductive rings (first conductive ring, second conductive ring, and optionally third conductive ring) arranged at different radial positions. This segmentation allows each ring to independently influence the plasma distribution and etching rate at different zones, providing redundancy and stability even when individual rings wear out.
Solution Approach 2:
The invention changes the electrical parameters by introducing multiple conductive rings with different potentials (some connected to RF power, others to ground). This creates a more complex electrical field distribution that stabilizes plasma confinement and reduces the impact of wear on any single ring's performance.
2Productivity
If the conductive ring operates for extended periods, then productivity is maintained, but the ring wears out leading to sputtering and etching rate fluctuations
Solution Approach 1:
By segmenting the single ring into multiple rings, the wear and sputtering effects are distributed across multiple components rather than concentrating on one ring. This allows the system to maintain performance even when individual rings degrade, enabling longer continuous operation.
Solution Approach 2:
The additional conductive rings act as intermediaries that redistribute the plasma and ion flux, reducing the direct bombardment and sputtering on any single ring. The ground-connected rings particularly help to control and dissipate charged particle accumulation, reducing harmful sputtering effects.
3Manufacturing precision
If the first conductive ring is connected to RF power to control plasma, then etching rate is controlled, but RF signal direction changes due to wear affecting process consistency
Solution Approach 1:
The invention changes the electrical configuration from a single RF-connected ring to multiple rings with different potential connections (RF power and ground). This creates a more stable reference frame for the RF signal and establishes multiple pathways for current flow, preventing unilateral shifts in signal direction that would occur with wear on a single ring.
Solution Approach 2:
By connecting certain conductive rings to ground potential, the invention creates equipotential regions that stabilize the electrical field distribution. This grounding strategy provides a stable reference potential that counteracts the effects of wear-induced potential shifts in the RF-connected rings, maintaining consistent RF signal direction.
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
The second conductive ring effectively suppresses etching rate fluctuations and sputter rates, enhances plasma confinement, and maintains process stability by grounding the RF current, ensuring consistent etching performance even with worn-out rings.
Implementation Method 1
a second conductive ring disposed to surround the insulating ring, and connected to a ground potential
Implementation Method 2
a plasma generator configured to generate a plasma in the plasma processing chamber
Implementation Method 3
a first conductive ring disposed to surround a substrate on the substrate support
Data Source
AI summary
A plasma processing apparatus includes a plasma processing chamber; a plasma generator configured to generate a plasma in the plasma processing chamber; a substrate support disposed in the plasma processing chamber; a first conductive ring disposed to surround a substrate on the substrate support; an insulating ring disposed to surround the first conductive ring; and a second conductive ring disposed to surround the insulating ring, and connected to a ground potential.