Lithographic Exposure Control Using Predicted Substrate Position
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Solution Overview
Problem
Synchronization of substrate position and optical exposure in semiconductor lithographic devices is challenging due to mechanical vibrations, thermal fluctuations, and control system latencies, leading to misalignment and defects in fabricated devices.
Innovation Solution
Implementing advanced control algorithms and hardware solutions that create a constant relative motion between the substrate and radiation system, using high-speed position sensing and synchronization to predict substrate positions with higher sampling rates, and applying radiation operations based on these predictions to achieve precise and efficient patterning on large substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional synchronization methods are used to coordinate substrate movement and light projection, then system complexity is reduced, but manufacturing precision deteriorates due to misalignment from mechanical vibrations and control latencies
Solution Approach 1:
The patent replaces traditional mechanical synchronization systems with an optical measurement and computational prediction system. A light source and sensor detect substrate position and velocity, while a controller predicts future positions using mathematical models, eliminating reliance on complex mechanical coordination between substrate stage and light projection systems
Solution Approach 2:
The system performs preliminary measurement of substrate position and velocity before the actual exposure moment. By measuring at an earlier time and predicting the substrate's future position at the exposure moment, the system proactively compensates for motion and vibration effects before they cause misalignment
2Manufacturing precision
If substrate movement is measured at low sampling rates, then measurement system complexity is reduced, but manufacturing precision deteriorates due to insufficient position prediction accuracy
Solution Approach 1:
The patent introduces a computational prediction model as an intermediary between low-rate physical measurements and high-rate control requirements. The controller uses the measured position and velocity to mathematically predict substrate position at future exposure moments, effectively bridging the gap between low sampling rates and high precision requirements without requiring high-speed sensors
3Manufacturing precision
If high sampling rates are used to track substrate position, then manufacturing precision is improved, but productivity deteriorates due to increased data processing requirements
Solution Approach 1:
The system applies partial measurement by capturing only the essential parameters (position and velocity) at optimized sampling rates, rather than continuously tracking all possible motion parameters at maximum rates. This selective measurement approach provides sufficient accuracy for prediction while minimizing data processing burden
4Manufacturing precision
If complex control algorithms are implemented to compensate for vibrations and thermal fluctuations, then manufacturing precision is improved, but device complexity worsens
Solution Approach 1:
The patent implements a feedback-based predictive control system where substrate position and velocity are continuously measured and fed into a prediction model. The controller adjusts light projection timing and positioning based on predicted substrate positions, creating a closed-loop system that automatically compensates for vibrations and thermal drift without requiring complex real-time control algorithms
Data Source
AI summary
This application is directed to controlling a manufacturing process (e.g., related to semiconductor devices, additive nano- and micro-fabrication, etc.). Relative motion is created between a substrate and a radiation system in a predetermined direction. A first position of the substrate is measured at a first time using a sensor at a first sampling rate, and applied to generate a series of expected positions of the substrate at a second sampling rate that is higher than the first sampling rate. A second position of the substrate corresponds to a second time later than the first time, and is determined based on the series of expected positions. A radiation operation is controlled at the second time to process the substrate, e.g., to expose a selected active area of the substrate for a predetermined duration of time.