Dual-Material Edge Ring for Plasma Wear and Gas Leakage
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Solution Overview
Problem
Existing edge rings in plasma processing apparatuses face challenges in extending their lifespan and reducing heat transfer gas leakage due to material consumption and thermal expansion issues when exposed to plasma.
Innovation Solution
A dual-material edge ring configuration is employed, where a harder silicon carbide material is used for the upper member in contact with plasma and a softer silicon material for the lower member not in contact, with an intermediate member to mitigate thermal stress, reducing consumption and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a hard material like silicon carbide is used for the entire edge ring to extend lifespan, then plasma-induced consumption is reduced, but thermal stress and deformation increase due to thermal expansion
Solution Approach 1:
The edge ring is divided into two regions with different material properties: the upper member in contact with plasma is made of hard silicon carbide to resist consumption, while the lower member is made of softer silicon to provide thermal compliance and reduce stress. This local differentiation of material quality resolves the contradiction between durability and dimensional stability.
Solution Approach 2:
The edge ring employs a composite structure combining silicon carbide and silicon materials. The upper member uses silicon carbide for plasma resistance, while the lower member uses silicon for thermal management. This composite approach allows the system to simultaneously achieve extended lifespan and maintain dimensional stability under thermal load.
2Strength
If the edge ring is made of a single hard material, then consumption resistance is improved, but adhesion to the electrostatic chuck deteriorates
Solution Approach 1:
The lower member is made of softer silicon material that provides better adhesion to the electrostatic chuck, while the upper member uses hard silicon carbide for plasma resistance. This local quality differentiation ensures both strong adhesion and consumption resistance without compromising either function.
3Reliability
If a soft material is used for the entire edge ring, then adhesion and stress tolerance are improved, but plasma-induced consumption increases
Solution Approach 1:
The upper member exposed to plasma is made of hard silicon carbide to minimize material consumption, while the lower member is made of softer silicon to ensure good adhesion to the electrostatic chuck. This spatial differentiation of material properties resolves the contradiction between adhesion reliability and consumption resistance.
4Ease of manufacture
If the edge ring structure is simplified to a single material, then manufacturing is easier, but thermal stress management deteriorates
Solution Approach 1:
The edge ring uses a composite structure with silicon carbide upper member and silicon lower member. This composite design specifically addresses thermal stress management by combining materials with different thermal properties, allowing the system to better withstand thermal expansion and contraction cycles during plasma processing.
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 dual-material configuration extends the edge ring's lifespan by reducing plasma-induced consumption and minimizes heat transfer gas leakage from the gap between the edge ring and electrostatic chuck.
Implementation Method 1
a first member made of a first material and having a contact surface with plasma generated inside the processing container
Implementation Method 2
A heat transfer gas such as helium (He) is supplied to the lower surface of the edge ring disposed on the outer circumferential side of the electrostatic chuck, and, as a result, the temperature of the edge ring is controlled
Implementation Method 3
the focus ring is electrostatically adsorbed during a carry-in/out of a wafer and a waferless dry cleaning (WLDC)
Data Source
AI summary
An edge ring includes a first member made of a first material and having a contact surface with plasma generated inside the processing container, and a second member made of a second material having Young's modulus lower than that of the first material. The second member is provided on a side opposite to the contact surface of the first member such that a combined structure of the first member and the second member surrounds a periphery of a substrate placed on a stage inside a processing container of a plasma processing apparatus.