Lithography Movable Body Encoder Air Fluctuation Compensation
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Solution Overview
Problem
In lithography processes for manufacturing electronic devices, the precision position control of substrates relative to projection optical systems is hindered by air fluctuations due to long optical paths in existing encoder systems, particularly in optical interferometer systems.
Innovation Solution
A movable body apparatus with a first and second movable body, a reference member, and measurement systems using multiple heads and grating members to acquire position information, allowing for precise control and correction of movement by switching measurement beams between grating areas, thereby reducing the influence of air fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical interferometer system is used for position measurement, then measurement capability is provided, but air fluctuation influences the measurement precision
Solution Approach 1:
The patent divides the measurement system into multiple independent measurement units (first measurement system with first heads and first grating member, second measurement system with second head and second grating member). Each measurement unit operates independently with shorter optical paths, reducing the cumulative effect of air fluctuations on the overall measurement precision.
Solution Approach 2:
The patent transitions from a single long optical path measurement approach to a multi-dimensional array of shorter optical paths by arranging multiple heads and grating members in spatial distribution. This dimensional change allows parallel measurement across different locations, minimizing the impact of localized air fluctuations.
2Measurement precision
If a single head and grating member are used, then device complexity is reduced, but measurement coverage and precision are insufficient
Solution Approach 1:
The measurement system is segmented into multiple functional units (multiple heads, multiple grating members) that can be independently configured. This segmentation allows the system to achieve high measurement precision through distributed sensing while maintaining modular architecture that manages complexity.
Solution Approach 2:
The patent designs the measurement systems with universal functionality where multiple heads and grating members serve both individual measurement functions and collective coordination functions. The control system integrates measurements from multiple sources to achieve comprehensive position measurement, making the system multi-functional in nature.
3Measurement precision
If measurement beam switches between grating areas, then measurement continuity is maintained, but system control complexity increases
Solution Approach 1:
The control system implements feedback mechanisms to monitor the positions of measurement beams relative to grating areas. When a beam approaches the boundary of a grating area, the system automatically triggers switching to an adjacent grating area, ensuring continuous measurement without gaps. This feedback control maintains measurement precision while managing switching complexity.
Solution Approach 2:
The system performs preliminary actions by pre-configuring multiple grating areas and establishing switching criteria before measurement begins. The control system is pre-programmed with the spatial relationships between grating areas, allowing automatic and seamless beam switching without real-time complex calculations, thus maintaining continuity while reducing operational complexity.
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 solution enhances the precision of position control for substrates, improving exposure accuracy by minimizing the impact of air fluctuations and maintaining high precision in the lithography process.
Implementation Method 1
in the case of obtaining position information on the substrate using an optical interferometer system, since the optical path of the laser to the bar mirror becomes long, influence of air fluctuation cannot be ignored
Data Source
AI summary
A movable body apparatus is provided with: a substrate holder which holds a substrate and which can move in the X- and Y-axis directions; a Y coarse movement stage which can move in the Y-axis direction; a first measurement system which acquires position information on substrate holder by means of heads provided on substrate holder and a scale provided on Y coarse movement stage; a second measurement system which acquires position information on Y coarse movement stage by means of heads provided on Y coarse movement stage and a scale; and a control system which controls the position of substrate holder based on position information acquired by first and second measurement systems. The first measurement system irradiates a measurement beam while moving heads in X-axis direction with respect to the scale, and second measurement system irradiates a measurement beam while moving heads in Y-axis direction with respect to the scale.