Electrostatic Chuck Holding Surface Groove Design for Cooling Gas Leakage
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Solution Overview
Problem
Existing electrostatic chuck devices in plasma etching apparatuses face challenges in uniformly controlling the surface temperature of the focus ring, leading to in-plane temperature variations of the wafer, due to leakage of cooling gas and increased pressure, which cannot be sufficiently managed by existing methods.
Innovation Solution
The electrostatic chuck device incorporates a holding portion with a specific annular groove and through-hole design, where the holding surface has a controlled shape and dimensions to minimize gas leakage, ensuring a positive or negative inclination and limited height difference between the inner and outer peripheries, and the leak area is kept below 0.7 mm², thereby reducing gas leakage and enhancing temperature control.
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 the gas leakage increases
Solution Approach 1:
The patent uses a flexible seal ring made of elastomer material that conforms to the holding surface contours. This flexible seal ring is pressed against the holding surface by elastic deformation, creating a tight seal that prevents cooling gas leakage while allowing the focus ring to be cooled effectively by the pressurized cooling gas flowing through the groove portion.
Solution Approach 2:
The patent creates a localized sealed environment by forming a groove portion that surrounds the mounting surface and uses a seal ring at specific locations. This local sealing approach confines the cooling gas to the needed area (around the focus ring) without requiring a complete system-wide seal, preventing leakage while maintaining effective cooling where needed.
2Temperature
If the holding surface shape is optimized to reduce gas leakage, then the temperature control is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent specifies precise geometric parameters for the holding surface, including inclination angle (0-15 degrees) and height difference (0-10 micrometers) between inner and outer peripheries. These controlled parameters create an optimal surface shape that prevents gas leakage and ensures uniform temperature distribution, while the ranges provided allow for practical manufacturing tolerances.
Solution Approach 2:
The holding surface is pre-formed during the manufacturing process with the specified inclination and height characteristics before the device is assembled and put into service. This preliminary shaping ensures that the gas flow and sealing characteristics are optimized from the start, preventing leakage issues before operation begins.
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 design effectively reduces gas leakage, allowing for better control of the cooling gas pressure and temperature uniformity of the focus ring and the wafer, improving the electrostatic chuck device's ability to maintain consistent surface temperatures.
Implementation Method 1
a cooling element configured to cool the focus ring
Implementation Method 2
a cooling medium is circulated through a temperature adjustment base part of the electrostatic chuck device to cool the wafer from the lower side
Implementation Method 3
upper surfaces of the holding portion, which are located on both sides of the groove portion in a width direction, form a holding surface that comes into contact with the focus ring and holds the focus ring
Implementation Method 4
an electrostatic chuck device capable of mounting and fixing a wafer (plate-shaped sample) on a sample table (mounting table)
Data Source
AI summary
An electrostatic chuck device comprising a mounting table having a mounting surface, a focus ring; and a cooling element, wherein the mounting table has a holding portion surrounding the mounting surface, the holding portion has an annular groove portion having a through-hole, the holding portion has inner and outer peripheral surfaces which hold the focus ring and are located on both sides of the groove portion, the holding surface satisfies conditions (i) and (ii), (i) a straight line connecting a first point corresponding to an innermost periphery of the holding surface and a second point corresponding to an outermost periphery of the holding surface has a positive or a negative inclination from the innermost periphery toward the outermost periphery, wherein a difference between a height of the first point and a height of the second point is 0 μm to 10 μm, and (ii) leak areas of the inner peripheral surface and the outer peripheral surface are less than 0.7 mm2.