Exposure Apparatus Focus Correction via Angle-View Control
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Solution Overview
Problem
Existing exposure apparatuses face challenges in improving focus accuracy and throughput due to increased measurement errors when accelerating the substrate stage, as focus measurement is performed with deviations from the target position, requiring more effective correction methods.
Innovation Solution
The exposure apparatus employs a detection optical system with a control device that calculates a focus correction formula based on the exposure angle of view, step direction, and target shot region position, adjusting the substrate stage to accurately align the substrate surface with the focus plane, thereby correcting focus residuals and improving measurement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the acceleration of the substrate stage is increased to improve throughput, then the throughput is improved, but measurement errors increase due to deviation from target position
Solution Approach 1:
The system performs focus measurement in advance before the substrate stage reaches the target position, and calculates correction values based on the measured focus residuals. This preliminary measurement and correction approach allows the stage to maintain higher acceleration while still achieving accurate focus alignment through subsequent correction.
Solution Approach 2:
The system implements feedback control by measuring focus residuals during stage movement, calculating correction values, and applying these corrections to adjust the substrate stage position. This closed-loop feedback mechanism enables the system to compensate for measurement errors caused by acceleration, maintaining measurement precision while improving throughput.
2Productivity
If focus measurement is performed in advance by relaxing settling tolerance, then throughput is improved, but measurement errors increase due to stage deviation
Solution Approach 1:
Focus measurement is performed in advance before the substrate stage reaches the target position, with relaxation of settling tolerance. The measured focus residuals are then used to calculate correction values that compensate for the stage deviation, enabling early measurement without sacrificing accuracy.
Solution Approach 2:
The system changes the timing parameter of focus measurement to occur during stage movement rather than after settling. By adjusting when the measurement is taken and applying corresponding correction values, the system maintains measurement precision while improving throughput through relaxed settling requirements.
3Manufacturing precision
If feedback control is used to improve focus accuracy, then focus accuracy is improved, but the speed of focusing operation decreases
Solution Approach 1:
Focus measurement and correction value calculation are performed in advance before the substrate stage reaches the target position. This preliminary action allows the focusing operation to begin earlier, maintaining high speed while achieving accurate focus alignment through subsequent correction application.
Solution Approach 2:
The system skips the traditional sequence of settling first then measuring by performing focus measurement during stage movement. This rushing through the settling phase maintains high focusing speed while correction values are calculated and applied to ensure accurate focus alignment.
Data Source
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AI summary
An exposure apparatus that exposes a substrate is provided. The apparatus comprises a stage configured to hold and move the substrate, and a controller configured to control focus driving of the stage based on a measurement value and a correction value obtained for the focus driving of the stage for a shot region on the substrate. The controller is configured to determine the correction value in accordance with an angle of view at a time of exposure.