Reticle Levitation Chuck for Low-Impact Exchange Alignment
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Solution Overview
Problem
In photolithography, the rapid swapping of reticles during integrated circuit production causes vibration and wear, leading to manufacturing defects and increased maintenance costs, as the electrostatic chuck's clamping process can result in misalignment and particle generation.
Innovation Solution
Levitating the reticle using an electrostatic field before clamping, allowing precise control of its position, orientation, and shape to minimize contact stress and particle generation, and using sensors and motors to dampen lateral motion, ensuring accurate and low-impact clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electrostatic chuck is moved rapidly toward the reticle for quick clamping, then manufacturing time is reduced, but vibration and wear increase causing defects
Solution Approach 1:
The system performs preliminary alignment and positioning of the reticle using the electrostatic field before final clamping contact is made. The reticle is levitated and positioned with high precision, and its shape is adjusted in advance, so that when contact occurs, minimal adjustment and vibration are needed, thus maintaining both speed and precision
2Reliability
If the electrostatic chuck clamps the reticle with high force, then clamping stability is improved, but particle generation and reticle wear increase
Solution Approach 1:
The system replaces direct mechanical contact and force-based clamping with an electrostatic field-based clamping mechanism. The electrostatic field holds the reticle with distributed forces across the reticle surface, achieving stable clamping without the localized high-stress contact points that generate particles and wear
3Device complexity
If the reticle is clamped without levitation, then the process is simpler and faster, but misalignment and lateral motion cause wear and defects
Solution Approach 1:
The electrostatic field acts as an intermediary between the chuck and the reticle, enabling precise control of the reticle's position and orientation during the approach and clamping phases. This intermediary field allows for deterministic control of contact forces and minimizes lateral motions that would cause wear
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 approach reduces wear and tear on the reticle and electrostatic chuck, decreases manufacturing time, and enhances the accuracy of reticle placement, thereby improving the manufacturing process by minimizing defects and maintenance costs.
Implementation Method 1
Levitating a reticle via an electrostatic field (i.e. lifting the reticle prior to an electrostatic chuck clamping the reticle)
Implementation Method 2
the reticle can be shaped (e.g. bowed or bent) to reduce stress and wear and tear when contact is made with the chuck
Implementation Method 3
using sensors and motors to dampen lateral motion
Data Source
AI summary
An electrostatic chuck includes electrodes to clamp a workpiece, electrodes to electrostatically levitate and position the workpiece, and sensors to detect position and orientation of the workpiece. Lateral motion of the workpiece relative to the electrostatic chuck can be damped prior to clamping.