Electrostatic Chuck Insulating Member Flange Design
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Solution Overview
Problem
Conventional electrostatic chucks face challenges in achieving both uniform wafer temperature and high insulating performance, as increasing the thickness or creepage distance of the insulating member to enhance insulation can lead to non-uniform temperature distribution, while reducing the diameter of the penetrating hole to maintain temperature uniformity may result in insulation failure.
Innovation Solution
An electrostatic chuck design featuring a ceramic base with an embedded electrode, a terminal inserted through a penetrating hole, and an insulating member with a flange portion that contacts the ceramic base, providing a long creepage distance and high dielectric strength, made from materials like aluminum nitride with a high thermal conductivity, and using a high-insulating adhesive to ensure effective insulation and temperature uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness or creepage distance of the insulating member is increased to enhance insulation performance, then insulating performance is improved, but temperature uniformity deteriorates
Solution Approach 1:
The insulating member is designed with a flange portion that extends radially outward from the terminal insertion region, utilizing the radial dimension to increase creepage distance without increasing the axial thickness. This dimensional approach allows the insulating member to provide sufficient creepage distance (preventing surface discharge) while maintaining a compact thickness that does not create significant heat transfer barriers, thus resolving the contradiction between insulating performance and temperature uniformity.
2Reliability
If the diameter of the penetrating hole is increased to accommodate thicker insulating member or longer creepage distance, then insulating performance is improved, but temperature uniformity deteriorates
Solution Approach 1:
Instead of increasing the penetrating hole diameter axially, the design extends the insulating member's protective function radially through the flange portion. This allows the creepage distance to be increased in the radial direction while keeping the penetrating hole diameter small, thereby maintaining good thermal contact between the temperature control member and ceramic base while achieving sufficient insulation.
3Temperature
If the diameter of the penetrating hole is decreased to maintain temperature uniformity, then temperature uniformity is improved, but insulating performance deteriorates
Solution Approach 1:
The flange portion of the insulating member extends radially outward to provide sufficient creepage distance, compensating for the small penetrating hole diameter. This radial extension ensures that surface discharge paths are sufficiently long even when the hole diameter is minimized, allowing the temperature control member to maintain excellent thermal contact with the ceramic base while the insulating member provides adequate insulation against high voltage terminals.
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 design achieves both high insulating performance and uniform wafer temperature, enhancing the reliability and surface uniformity during processes like wafer etching, preventing dielectric breakdown and creeping discharge, and maintaining efficient heat transfer.
Implementation Method 1
it is necessary that the dielectric voltage of the insulating member itself be high, and that no creeping discharge occur in an area where an end face of the insulating member is in contact with the back face of the ceramic base
Implementation Method 2
the temperature of the surface of the semiconductor substrate held onto this electrostatic chuck is controlled to be constant by the heat transfer across this temperature control member and the electrostatic chuck
Implementation Method 3
This electrostatic chuck holds the semiconductor wafer by generating electrostatic force between a holding face of the electrostatic chuck and the semiconductor wafer set on the holding face
Data Source
AI summary
An electrostatic chuck includes a ceramic base having an electrode embedded in vicinity to a holding face for holding a substrate. On a back side of this ceramic base, provided are a terminal connected to the electrode, a wafer temperature control member, and an insulating member for insulating the temperature control member from the terminal. This insulating member has a flange portion on its end portion in contact with the ceramic base, and is made of highly thermal conductive ceramics.