Electrostatic Chuck Charge Dissipation Coating for Wafer Release
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Solution Overview
Problem
Electrostatic chucks face issues with charge accumulation leading to 'sticking' problems, where wafers become difficult to unclamp, potentially causing damage and processing interruptions, and excessive charge can result in doping non-uniformities and arcing in plasma doping ion implanters.
Innovation Solution
The implementation of a charge dissipation layer (CDL) coating on the electrostatic chuck, with a conductive bridge configuration that prevents electrical coupling between the electrode pattern and the CDL, allowing for continuous grounding and efficient charge dissipation, thereby preventing wafer sticking and ensuring uniform processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring loaded grounding pins are used to dissipate charge, then charge dissipation is provided, but the number of grounding points is limited to three and sharp edges can damage the workpiece
Solution Approach 1:
The grounding function is segmented into multiple discrete conductive elements (protrusions) distributed across the chuck surface, replacing the single three-pin grounding mechanism. Each protrusion acts as an independent grounding point, collectively providing enhanced charge dissipation capability while avoiding the limitation of only three grounding points.
Solution Approach 2:
The grounding structures are designed with rounded edges and distributed across the surface, providing localized charge dissipation at multiple points rather than relying on three sharp-edged pins. This local quality approach prevents workpiece damage while maintaining effective charge dissipation.
2Object-generated harmful factors
If conductive coating is applied to reduce clamping force and particle generation, then particle generation is reduced, but electrostatic forces between embossments and wafer are interfered with
Solution Approach 1:
The chuck surface is segmented into distinct functional zones: embossment regions for clamping, gap regions for charge dissipation, and protrusion regions for grounding. This segmentation allows each zone to perform its specific function without interfering with others, maintaining clamping force stability while reducing particle generation.
Solution Approach 2:
Different surface properties are applied to different locations: embossments have properties optimized for clamping, gaps provide charge dissipation pathways, and protrusions provide grounding. This local quality differentiation enables simultaneous achievement of stable clamping and reduced particle generation.
3Ease of operation
If charge accumulation is allowed to control sticking, then workpiece handling is simplified, but doping non-uniformities and arcing occur in plasma doping ion implanters
Solution Approach 1:
The chuck is pre-configured with multiple charge dissipation pathways (gaps and protrusions) that are activated automatically during processing. This preliminary action prevents charge accumulation before it can cause harmful effects, eliminating the need for intentional throughput limiting while maintaining ease of operation.
Solution Approach 2:
The gap regions and protrusions act as intermediary charge dissipation pathways between the workpiece and chuck body. These intermediaries provide controlled charge transfer, preventing excessive charge accumulation that would lead to doping non-uniformities and arcing, while maintaining proper workpiece handling.
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 solution effectively reduces wafer sticking issues and prevents charge accumulation, ensuring reliable wafer handling and uniform processing by providing a low resistance path for charges to ground, thus enhancing the performance of electrostatic chucks.
Implementation Method 1
the charge dissipation layer coating (or CDL coating) on an uppermost layer of the electrostatic chuck provides grounding for a wafer substrate that is placed thereon for charge dissipation
Implementation Method 2
Electrostatic charge may accumulate on the workpiece and also on the platen surface supporting the workpiece
Data Source
AI summary
An electrostatic chuck solves the problem of wafer sticking by providing conductive paths on raised embossments that are bridged together and are connected to ground that support the wafer substrate above the surface of the electrostatic chuck. Further, laterally spaced electrode patterns and electrode elements which are spaced laterally and longitudinally away from the raised embossments reduce or eliminate electrical coupling during wafer clamping between conductively coated embossments and the electrode elements, thereby creating a low resistance path for charges remaining on the wafer after declamping to promptly travel to ground. The conductive bridge and electrode pattern configuration also substantially reduces or eliminates any charge build up on the conductive bridge(s) during clamping in order that charge build up in “islands” (worn portions of the insulator layer of the main field area) do not affect the charge dissipation from the wafer substrate through the conductive bridges to ground.