Electrostatic Chuck Clamping for Bowed Substrates With Lower Friction
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Solution Overview
Problem
Bowed substrates, such as semiconductor wafers, are difficult to clamp to electrostatic chucks using conventional methods, leading to high clamping voltages and unwanted particle generation due to increased friction.
Innovation Solution
A method and system for clamping substrates that involves measuring the substrate bow and determining specific AC and DC voltages to be applied to electrodes on a substrate support, allowing for effective clamping with lower voltage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional clamping methods are used on bowed substrates, then clamping force is achieved, but high clamping voltages are required leading to increased friction and particle generation
Solution Approach 1:
The electrode array is divided into multiple independently controllable segments that can be addressed individually or in groups. This segmentation allows different voltage levels to be applied to different regions of the substrate, enabling effective clamping of bowed substrates by targeting specific gap regions without requiring uniformly high voltages across the entire substrate surface, thereby reducing overall friction and particle generation
Solution Approach 2:
Different voltage levels are applied to different local regions of the substrate based on the measured bow profile. Regions with larger gaps receive higher voltages to achieve adequate clamping, while regions with smaller gaps receive lower voltages. This local quality approach minimizes unnecessary high-voltage application, reducing friction-induced particle generation in areas where it is not needed
2Reliability
If high clamping voltages are applied to bowed substrates, then adequate clamping is achieved, but friction between substrate and ESC increases
Solution Approach 1:
The system dynamically adjusts voltage levels based on real-time measurements of substrate bow and gap variations. By continuously monitoring the substrate position and adjusting the voltage distribution accordingly, the system maintains reliable clamping while minimizing friction through optimized voltage application. The dynamic adaptation allows the system to respond to changing substrate conditions without requiring consistently high voltages
Solution Approach 2:
The invention changes the electrical parameters (voltage levels) applied to different electrode segments based on the measured substrate bow characteristics. By adjusting these parameters to match the actual gap distribution, the system achieves reliable clamping with lower overall voltage requirements, thereby reducing friction between the substrate and electrostatic chuck surface
3Ease of operation
If uniform voltage is applied across all electrodes, then simple control is maintained, but effective clamping of bowed substrates cannot be achieved
Solution Approach 1:
The system performs preliminary measurement of the substrate bow profile before applying clamping voltages. Based on these pre-measurements, the control system pre-calculates the optimal voltage distribution across different electrode segments. This preliminary action enables the system to achieve effective clamping of bowed substrates without requiring complex real-time control algorithms during the actual clamping process
Solution Approach 2:
The system incorporates feedback from substrate bow measurements to adjust the voltage distribution pattern. By using the measured bow profile as feedback information, the control system can determine the appropriate voltage levels for each electrode segment, achieving effective clamping while maintaining relatively simple control logic based on pre-established voltage-bow relationships
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 solution enables efficient clamping of bowed substrates with reduced particle generation by minimizing friction, achieved through the controlled application of electrostatic forces tailored to the substrate's bow measurement.
Implementation Method 1
applying the first voltage to the first electrode and the second voltage to the second electrode to clamp the substrate to the substrate support
Data Source
AI summary
Methods and apparatus for clamping a substrate comprise i. placing a substrate on a clamping surface of a substrate support having a plurality of electrodes spaced from one another including a first electrode and a second electrode; ii. measuring substrate bow of the substrate; iii. determining, based on the measured substrate bow, a first voltage to be applied to the first electrode and a second voltage to be applied to the second electrode, wherein the first voltage is an AC voltage and the second voltage is an AC or a DC voltage; and iv. applying the first voltage to the first electrode and the second voltage to the second electrode to clamp the substrate to the substrate support.