Dual Encoder Movable Body Apparatus for Lithography Positioning
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Solution Overview
Problem
Conventional exposure apparatuses face challenges in accurately positioning substrates during lithography processes due to air fluctuations and the increasing size of substrates, which complicates the preparation of scales to cover the entire moving range, especially in step-and-scan methods.
Innovation Solution
A movable body apparatus with a first and second movable body, where the second body moves synchronously with the first along one direction, utilizing a dual encoder system to acquire position information in both directions, allowing efficient position control within a two-dimensional plane, and an exposure apparatus that uses this setup to form patterns on substrates with improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical interferometer system with a bar mirror is used to acquire position information, then positioning capability is provided, but the system becomes complex and requires large-scale components that are difficult to prepare for large substrates
Solution Approach 1:
The patent replaces the optical interferometer system with an encoder system that uses a scale and head mechanism. This substitution eliminates the need for complex bar mirrors and optical components, simplifying the overall system structure while maintaining positioning capability for large substrates
Solution Approach 2:
The patent divides the position measurement function into separate encoder systems that can independently measure positions along different directions. This segmentation allows each encoder to be optimized for its specific direction without requiring a complete optical interferometer system, reducing overall complexity
2Adaptability or versatility
If the substrate size increases, then more large substrates can be processed, but it becomes difficult to prepare a scale that can cover the entire moving range
Solution Approach 1:
The patent employs multiple encoder systems, each responsible for measuring position along a specific direction. This segmentation allows the scale to be divided into manageable sections that can be independently prepared and positioned, eliminating the need for a single massive scale to cover the entire moving range of large substrates
3Measurement precision
If air fluctuation influence is considered, then positioning accuracy deteriorates, but reducing air fluctuation influence requires additional air-conditioning systems that increase device complexity
Solution Approach 1:
The patent replaces the optical interferometer system with an encoder system that is less susceptible to air fluctuation effects. The encoder mechanism uses mechanical or magnetic fields rather than optical paths that are sensitive to air conditions, thereby reducing the need for complex air-conditioning systems while maintaining positioning accuracy
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 reduces the influence of air fluctuations, enhances positioning accuracy, and allows for more compact and cost-effective exposure apparatuses, eliminating the need for large bar mirrors and partial air-conditioning systems, while supporting large substrates and masks.
Implementation Method 1
a first encoder system that has one of a scale and a head disposed at the first movable body and the other of the scale and the head disposed at the second movable body, that acquires position information of the first movable body at least in the second direction on the basis of output of the head
Data Source
AI summary
A substrate stage apparatus provided with: a substrate holder that can be moved in a plane including an X-axis and a Y-axis; a head unit that can be moved synchronously with the substrate holder along the Y-axis; an encoder system for measuring substrate position, the system including a scale disposed on the substrate holder, and heads disposed on the head unit, and acquiring the X-axis direction and the Y-axis direction position information of the substrate holder on the basis of the output of the heads; an encoder system for measuring head-unit position, the system acquiring the Y-axis direction position information of the head unit; and a position control system that controls the position of the substrate holder within the XY plane on the basis of the output of the encoder system for measuring substrate position and the encoder system for measuring head-unit position.