Position Sensor Error Characterization for Microlithography Stages
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Solution Overview
Problem
Position sensor errors in microlithography systems lead to placement inaccuracies, affecting the performance of microlithographic processes, measurements, and inspections due to increased resolution and alias frequency issues.
Innovation Solution
A method for determining and compensating for position sensor errors in substrate pattern systems by calculating errors using position data sampled at a rate based on the sensor's fundamental period, with predetermined speed and sampling rate, and applying compensation data to correct for these errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensor resolution is increased to improve positioning accuracy, then measurement precision is improved, but position sensor errors and alias frequency problems occur
Solution Approach 1:
The system performs preliminary characterization of position sensor errors by moving the movable component at a predetermined speed and sampling position data at multiple sampling rates. This preliminary measurement enables subsequent compensation for sensor errors during actual microlithographic operations, resolving the contradiction between high resolution and sensor reliability.
Solution Approach 2:
The system implements feedback by using measured position sensor errors to generate correction values that are applied during positioning operations. The control unit continuously monitors position data, compares it with expected values based on predetermined speed and sampling rate, and applies compensatory corrections to maintain positioning accuracy despite sensor errors.
2Measurement precision
If position sensor resolution is increased, then measurement precision is improved, but placement errors and positioning system accuracy degradation occur
Solution Approach 1:
The control unit uses feedback from sampled position data to detect placement errors caused by sensor resolution issues. By comparing actual position measurements with expected positions based on predetermined speed and sampling rate, the system generates correction values that compensate for placement errors and maintain manufacturing precision.
Solution Approach 2:
The system performs preliminary error characterization by sampling position data at multiple rates before actual positioning operations. This preliminary action establishes a correction profile that is applied during manufacturing operations to maintain placement accuracy despite high-resolution sensor limitations.
3Measurement precision
If sampling rate is increased to capture position data more frequently, then measurement precision is improved, but processing complexity and computational load increase
Solution Approach 1:
The system applies partial sampling by selecting specific sampling rates from a set of available rates based on the fundamental period of the position sensor. Instead of continuously sampling at maximum rate, the system uses only the necessary sampling frequency to characterize sensor errors, reducing processing complexity while maintaining measurement precision.
Solution Approach 2:
The system changes the sampling rate parameter dynamically based on the fundamental period of the position sensor. By adjusting the sampling rate to match the sensor's characteristics rather than using a fixed high rate, the system achieves accurate error characterization with reduced computational load and processing complexity.
Data Source
Figure 1A~1B
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AI summary
A method for determining a position sensor error in a substrate pattern system, wherein the substrate pattern system comprises a control unit, a movable component, a base, and at least one position sensor having a fundamental period and configured to measure a position of the movable component along at least one axis, the method comprising: moving (110) the movable component relative the base with a predetermined speed along the at least one axis, generating (120) position data indicating a position of the movable component relative the base, by the at least one position sensor, sampling (130) the position data with a sampling rate to generate sampled position data, wherein the sampling rate is based on the fundamental period of the at least one position sensor, calculating (140), by the control unit, the position sensor error along the at least one axis of the at least one position sensor based on the sampled position data, the predetermined speed and the sampling rate.