Electrostatic Chuck Focus Ring Sealing for Uniform Cooling
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Solution Overview
Problem
Existing electrostatic chuck devices struggle to uniformly control the surface temperature of the focus ring in plasma etching apparatuses due to gas leakage issues, especially when increasing cooling gas pressure, which leads to in-plane temperature variations on the wafer.
Innovation Solution
The electrostatic chuck device incorporates a mounting table with an annular groove and through-holes, where tubular insulators are inserted, and the holding surfaces are ground to specific surface roughness, flatness, and recess conditions to reduce gas leakage, ensuring the focus ring is securely held and cooled uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the pressure of cooling gas is increased to cool the focus ring, then the cooling effect is improved, but gas leakage increases
Solution Approach 1:
The patent uses a seal ring made of elastic material that flexes to conform to the focus ring surface, creating an effective seal that prevents cooling gas leakage while maintaining contact pressure for efficient heat transfer from the focus ring
Solution Approach 2:
The seal ring acts as an intermediary component between the cooling gas supply system and the focus ring, mediating the conflict between needing high gas pressure for effective cooling and needing to prevent gas leakage by providing a sealing interface
2Temperature
If the cooling gas pressure is increased, then the cooling efficiency is improved, but the uniformity of wafer surface temperature deteriorates due to temperature differences between the focus ring and mounting table
Solution Approach 1:
The patent applies different thermal management approaches to different regions: the focus ring receives active cooling through the sealed cooling gas flow, while the mounting table maintains a different temperature profile, creating locally optimized thermal conditions that result in overall uniform wafer surface temperature
Solution Approach 2:
The patent controls the pressure and flow parameters of the cooling gas to optimize the temperature of the focus ring, adjusting these parameters to achieve the desired thermal balance between the focus ring and mounting table for uniform wafer surface temperature
3Reliability
If a seal ring is added to prevent gas leakage, then gas sealing is improved, but device complexity increases
Solution Approach 1:
The seal ring is designed as a simple, replaceable component made of elastic material that can be easily installed and replaced if needed, providing effective sealing without adding permanent complexity to the overall device structure
Solution Approach 2:
The elastic seal ring provides effective gas sealing through its flexibility and ability to conform to surfaces, achieving reliable sealing with a simple geometric form that does not significantly increase device 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
This configuration effectively reduces gas leakage, allowing for precise control of the focus ring temperature and uniform surface temperature of the wafer, improving thermal management in plasma etching processes.
Implementation Method 1
a cooling element for cooling the focus ring
Implementation Method 2
the holding surfaces... that are in contact with the focus ring and hold the focus ring
Data Source
AI summary
An electrostatic chuck device includes: a mounting table provided with amounting surface on which a plate-shaped sample is mounted; an annular focus ring; and a cooling element for cooling the focus ring, in which the mounting table has a holding portion provided to surround the mounting surface, and the holding portion includes an annular groove surrounding the mounting surface, and a through-hole that is open on a bottom surface of the groove, wherein a tubular insulator has been inserted into the through-hole, the holding portion has upper surfaces, which are located on both sides of the groove in a width direction, as holding surfaces that are in contact with the focus ring and hold the focus ring, wherein the holding surface satisfies the following conditions (i) to (iii); (i) surface roughness is 0.05 μm or less, (ii) a flatness is 20 μm or less, and (iii) the holding surface does not have a recess having a depth of 1.0 μm or more and extending in a direction intersecting the holding surface.