Plasma Processing Focus Ring Capacitance Reduction
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Solution Overview
Problem
In plasma processing, the focus ring in capacitively coupled plasma processing apparatuses is prone to deterioration and high replacement costs due to ion bombardment, especially with increased high-frequency power usage, leading to a shortened lifespan and higher consumption rates.
Innovation Solution
A plasma processing apparatus configuration featuring a peripheral dielectric member with higher impedance than the main dielectric member, which reduces the electrostatic capacitance per unit area between the electrode and the focus ring, thereby decreasing the energy of ions bombarding the focus ring and minimizing its consumption, along with a two-piece focus ring structure for extended lifespan and easy replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high frequency power is increased to improve processing performance and reduce processing time, then plasma density and ion bombardment energy increase, but the wear rate of the focus ring increases and its lifespan decreases
Solution Approach 1:
The focus ring is divided into a two-piece structure consisting of an inner focus ring and an outer focus ring. The inner focus ring can be replaced independently when worn, while the outer focus ring continues to provide protection. This segmentation allows selective replacement of only the worn component rather than the entire focus ring assembly.
Solution Approach 2:
A peripheral dielectric member is introduced to change the electrostatic capacitance parameter of the system. By reducing the electrostatic capacitance per unit area between the electrode and the focus ring, the energy of ions bombarding the focus ring is decreased, thereby reducing wear rate and extending lifespan.
2Reliability
If a focus ring is attached to protect the susceptor from ion bombardment, then the susceptor is protected, but the focus ring itself is consumed and requires frequent replacement
Solution Approach 1:
A peripheral dielectric member is introduced as an intermediary element between the electrode and the focus ring. This dielectric member modifies the electric field distribution and reduces the electrostatic capacitance, thereby decreasing the energy transferred to ions that bombard the focus ring and reducing its consumption rate.
Solution Approach 2:
The focus ring is segmented into inner and outer pieces that can be replaced independently. This allows the protective function to be maintained while reducing overall consumption by replacing only the worn inner portion rather than the entire focus ring structure.
3Duration of action of stationary object
If a two-piece focus ring structure is used to extend lifespan through selective replacement, then replacement costs are reduced, but device complexity increases
Solution Approach 1:
The focus ring is divided into an inner focus ring and an outer focus ring that can be independently replaced. The inner focus ring is designed to be replaceable while the outer focus ring remains fixed, creating a modular structure that simplifies maintenance operations despite the increased structural complexity.
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 solution effectively suppresses the consumption of the focus ring without affecting plasma processing performance, improving the lifespan and reducing operational costs by reducing ion bombardment energy and allowing for selective replacement of worn-out ring components.
Implementation Method 1
an electrostatic capacitance per unit area applied between the first electrode and the focus ring is smaller than an electrostatic capacitance per unit area applied between the first electrode and the substrate by the main dielectric member
Implementation Method 2
the energy of ions bombarding the focus ring is smaller than the energy of ions bombarding the substrate by the main dielectric member
Implementation Method 3
a first high frequency power supply unit for applying a first high frequency power having a first frequency to either the first electrode or the second electrode
Implementation Method 4
a processing gas supply unit for supplying a processing gas to a processing space formed between the first electrode and the second electrode
Data Source
AI summary
A plasma processing apparatus includes a processing chamber, a first electrode and a second electrode disposed to face each other, a high frequency power supply unit for applying a high frequency power to either the first electrode or the second electrode, a processing gas supply unit for supplying a processing gas to a processing space, and a main dielectric member provided at a substrate mounting portion on a main surface of the first electrode. A focus ring is attached to the first electrode to cover a peripheral portion of the main surface of the first electrode and a peripheral dielectric member is provided in a peripheral portion on the main surface of the first electrode so that an electrostatic capacitance per unit area applied between the first electrode and the focus ring is smaller than that applied between the first electrode and the substrate by the main dielectric member.