Electrostatic Chuck Clamping for Bowed Substrates
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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 applying specific AC and DC voltages to electrodes on a substrate support to effectively clamp the substrate with lower voltage requirements, reducing friction and particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional clamping methods are used on bowed substrates, then clamping force is achieved, but high clamping voltages are required and friction increases leading to particle generation
Solution Approach 1:
The electrode array is divided into multiple independently controllable segments or zones along the substrate surface. Each segment can apply different voltage levels and waveforms (AC or DC) to different regions of the bowed substrate, allowing localized compensation for bow variations and reducing the peak voltage needed for effective clamping.
Solution Approach 2:
Different regions of the substrate receive tailored clamping conditions based on their local bow characteristics. The system measures the substrate bow profile and applies higher voltages to regions with larger gaps while using lower voltages where the substrate is already close to the chuck surface, thereby reducing overall friction and particle generation.
2Force
If high clamping voltages are applied to bowed substrates, then adequate clamping force is achieved, but friction between substrate and chuck increases
Solution Approach 1:
The system dynamically adjusts voltage parameters (magnitude, AC frequency, DC level) based on the measured substrate bow profile. By optimizing these electrical parameters for each local region, the system achieves sufficient clamping force with lower peak voltages, thereby reducing the friction that would otherwise occur with uniformly high voltage application.
3Device complexity
If uniform voltage is applied across all electrodes, then simplicity is maintained, but bowed substrates cannot be clamped effectively
Solution Approach 1:
The voltage applied to each electrode is made dynamic rather than static. The system continuously or periodically measures the substrate bow and adjusts the voltage distribution in real-time, allowing the clamping system to adapt to substrate variations and maintain effective clamping without requiring complex mechanical adjustments.
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 allows for efficient clamping of bowed substrates using lower clamping voltages, thereby reducing friction and particle generation, and improving the overall processing of substrates in semiconductor manufacturing.
Implementation Method 1
a first voltage to be applied to the first electrode and a second voltage to be applied to the second electrode... 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.