Dynamic Electrostatic Chuck Control to Prevent Wafer Inspection Arcing
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Solution Overview
Problem
Conventional electrostatic chucks in charged particle beam apparatuses face limitations in maintaining stable interactions with wafers due to position-dependent functionality, leading to issues like arcing and difficulty in detecting wafer defects during inspection, which can result in reduced throughput and imaging accuracy.
Innovation Solution
A dynamically controlled electrostatic chuck system with sensors and a controller that adjusts voltage parameters based on real-time measurements of capacitance and grounding resistance to maintain stable wafer interactions, preventing arcing and ensuring proper wafer placement and grounding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage is applied to electrodes to secure the wafer, then wafer attachment reliability is improved, but arcing and electrical instability occur
Solution Approach 1:
The patent implements dynamic voltage adjustment of the electrostatic chuck electrodes during wafer inspection. The control system continuously monitors wafer position and capacitance, then adjusts electrode voltages in real-time to maintain stable attachment without excessive voltage that causes arcing. This transforms the static high-voltage application into a dynamic, adaptive process that prevents electrical instability while maintaining reliable wafer securing.
Solution Approach 2:
The system employs feedback control by monitoring wafer-chuck capacitance and wafer position, then using this information to adjust electrode voltages. The control system receives feedback about wafer attachment status and electrical conditions, and dynamically modifies the voltage applied to electrodes to prevent arcing while maintaining secure attachment. This closed-loop control resolves the contradiction between needing high voltage for attachment and avoiding harmful arcing.
2Device complexity
If the electrostatic chuck maintains fixed position functionality, then control simplicity is improved, but wafer inspection accuracy deteriorates due to warping
Solution Approach 1:
The patent makes the electrostatic chuck position and voltage characteristics dynamic during inspection. The system adjusts electrode voltages based on real-time wafer position feedback to compensate for wafer bowing and warping. This dynamic adjustment maintains wafer flatness and inspection accuracy without requiring complex mechanical position control, resolving the contradiction between control simplicity and inspection precision.
Solution Approach 2:
The system changes electrical parameters (electrode voltages) dynamically during inspection to compensate for wafer deformation. By adjusting voltage levels and distribution across electrodes based on monitored wafer conditions, the system maintains optimal wafer-chuck interaction and inspection accuracy. This parameter-based control achieves precision without increasing mechanical complexity.
3Reliability
If real-time voltage adjustment is implemented, then wafer inspection reliability is improved, but system complexity increases
Solution Approach 1:
The patent integrates multiple functions into the existing electrostatic chuck control system. The same control system that manages chuck operation also performs real-time voltage adjustment for wafer position compensation and arcing prevention. By making the control system multi-functional rather than adding separate dedicated systems, the patent improves inspection reliability while minimizing the increase in overall system complexity.
Solution Approach 2:
The electrostatic chuck system performs self-adjustment through automated feedback control. The control system autonomously monitors wafer position and capacitance, then automatically adjusts electrode voltages without requiring external intervention or complex additional hardware. This self-service capability improves reliability while keeping system complexity manageable through automation rather than manual control.
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
Enhances the reliability and accuracy of wafer inspection by minimizing arcing and warping, thereby improving throughput and imaging quality in charged particle beam apparatuses.
Implementation Method 1
Placing a wafer on the e-chuck can generate an attracting force between a plurality of electrodes implemented in the e-chuck and the wafer. The attraction between the e-chuck and the wafer can be achieved by applying high voltages to the plurality of electrodes to attract and secure the charged wafer.
Implementation Method 2
receiving a measured capacitance between a plurality of electrodes in an electrostatic chuck and a wafer from a first sensor to determine a bow of the wafer
Implementation Method 3
the e-chuck may ground the wafer by using a pin implemented in the e-chuck, which may bias the wafer to a predefined voltage level
Data Source
AI summary
An electrostatic chuck control system configured to be utilized during an inspection process of a wafer, the electrostatic chuck control system comprising an electrostatic chuck of a stage configured to be undocked during the inspection process, wherein the electrostatic chuck comprises a plurality of components configured to influence an interaction between the wafer and the electrostatic chuck during the inspection process, a first sensor configured to generate measurement data between at least some of the plurality of components and the wafer, and a controller including circuitry configured to receive the measurement data to determine characteristics of the wafer relative to the electrostatic chuck and to generate adjustment data to enable adjusting, while the stage is undocked, at least some of the plurality of components based on the determined characteristics.