Metrology Substrate Position Measurement Thermal Expansion Compensation
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Solution Overview
Problem
The existing metrology machine processes are limited by the time required for substrate temperature adjustment, leading to reduced throughput due to the need for prolonged waiting periods before measurement can commence, as the substrate size changes with temperature differences between the climate chamber and the substrate.
Innovation Solution
The method involves conducting multiple measurement loops with temperature measurements to calculate a real grid by compensating for thermal expansion, allowing for immediate or near-immediate substrate placement on the metrology machine stage and subsequent measurement, reducing the overhead of temperature adjustment and increasing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the substrate is allowed to temperature-adjust before measurement, then measurement precision is improved, but productivity deteriorates due to extended waiting time
Solution Approach 1:
The patent performs preliminary temperature measurements during substrate transport and before full temperature adjustment completes. This allows the measurement process to overlap with the temperature adjustment process, eliminating the need to wait for complete thermal equilibrium before starting measurements.
Solution Approach 2:
The patent changes the measurement parameters dynamically based on substrate temperature. By measuring at multiple temperature states (during adjustment) and compensating for thermal expansion effects, the system maintains measurement precision across varying temperature conditions rather than requiring a single fixed temperature state.
2Productivity
If multiple measurement loops are performed during temperature adjustment, then productivity is improved, but measurement precision deteriorates due to thermal expansion distortions
Solution Approach 1:
The patent implements feedback by continuously monitoring substrate temperature during measurement loops and using this information to compensate for thermal expansion effects. The system measures temperature, calculates the resulting dimensional changes, and adjusts measurement results accordingly to maintain precision despite performing measurements during active temperature adjustment.
Solution Approach 2:
The patent performs an asymmetric number of measurement loops at different temperature states (e.g., more measurements at earlier temperature states when throughput benefits are greater), rather than distributing measurements uniformly across all temperature adjustment time. This optimizes the balance between capturing sufficient data for precision and minimizing total measurement time.
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 enables faster and more efficient measurement of substrate positions by predicting and compensating for thermal expansion, thereby reducing the time required for temperature adjustment and enhancing the overall throughput of substrates in metrology machines.
Implementation Method 1
As the size of a substrate changes with its temperature, a difference between substrate temperature and the temperature within a climate chamber of a metrology machine causes the substrate to change its size while sitting on the stage of the metrology machine
Data Source
AI summary
A method with increased throughput for measuring positions of structures on a substrate is disclosed. The substrate is taken from a load port of a metrology machine and is placed immediately in a stage of the metrology machine. At least two measurement loops are carried out, wherein a first measurement loop is started at a time when a substrate temperature is different from the temperature at the stage, and at least one second measurement loop is started at a time after the first measurement loop when the substrate temperature is different from the temperature at the stage. A model is used to calculate from the measured data, taken while there is a temperature mismatch between the stage and the substrate, a real grid of positions of structures on the substrate, corresponding to a situation where the temperature of the stage matches the temperature of the substrate.