Projection Exposure Apparatus Alignment Error Compensation
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Solution Overview
Problem
Conventional projection exposure apparatuses face errors due to differences between the focal planes of alignment and focal plane measuring systems, which are exacerbated by substrate warpage during semiconductor processing, necessitating a solution that compensates for these discrepancies while enabling large-field-of-view lithography with a simple structure and small footprint.
Innovation Solution
A projection exposure apparatus with a focal plane measuring system and an alignment measuring system, where the alignment measuring system includes focusing components that adjust based on substrate profile variations measured by the focal plane measuring system, allowing for computational compensation of positional changes and reducing errors between different focal planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If multiple fields of view are stitched together to achieve large-area lithography, then the exposure field-of-view is improved, but the alignment accuracy deteriorates due to stricter requirements on the alignment system
Solution Approach 1:
The patent divides the large-area substrate into multiple exposure regions, each covered by a separate projection optical system with its own alignment measuring system. This segmentation allows each region to be aligned independently with high precision while collectively covering a large area, resolving the contradiction between large FOV and alignment accuracy.
Solution Approach 2:
The patent introduces an intermediary computational processing step that collects coordinate data from multiple alignment measuring systems, performs coordinate transformation and integration, and generates comprehensive alignment information. This intermediary processing reconciles the alignment data from different regions, maintaining high alignment accuracy across the entire large-area substrate.
2Adaptability or versatility
If the measuring focal plane of the alignment measuring system and the focal plane measuring system are different, then both measurement functions can be provided, but measurement errors are introduced due to the need to switch between focal planes
Solution Approach 1:
The patent replaces the mechanical approach of physically switching between different focal planes with a computational coordinate transformation system. The alignment measuring system performs optical measurement at its focal plane, then the controller computationally transforms these coordinates to account for substrate profile variations, eliminating the need for mechanical focal plane switching and the associated measurement errors.
Solution Approach 2:
The patent changes the measurement parameters by allowing the alignment measuring system to operate at a fixed focal plane while computationally adjusting for substrate profile variations. Instead of changing the physical focal plane position, the system changes the coordinate reference frame through computational processing, maintaining measurement precision while providing versatility.
3Ease of manufacture
If conventional alignment and focal plane measurement systems are used separately, then each system can perform its dedicated function, but errors arise due to different focal planes requiring switching
Solution Approach 1:
The patent merges the alignment measuring system and focal plane measuring system into an integrated measurement system. Both measurement functions are performed simultaneously by the same optical system, eliminating the need to switch between separate systems and their different focal planes. This integration maintains the ease of manufacture of dedicated systems while improving exposure accuracy through unified measurement.
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 accurate alignment and exposure by compensating for substrate warpage-induced errors, ensuring high exposure accuracy and efficiency in large-area semiconductor device fabrication.
Implementation Method 1
a focal plane measuring system and an alignment measuring system both disposed between a reticle stage and a substrate stage
Implementation Method 2
the alignment measuring system is provided with focusing components. The focal plane measuring system measures variation in the surface profile of a substrate, and the focusing components effectuates focusing of the alignment measuring system based on the substrate profile variation measurement
Data Source
AI summary
A projection exposure apparatus is disclosed, including a focal plane measuring system (8) and an alignment measuring system (9) both disposed between a reticle stage (3) and a substrate stage (4). The alignment measuring system (9) is capable of focusing. The focal plane measuring system (8) measures variation in the surface profile of a substrate (5), and the alignment measuring system (9) effectuates focusing based on data obtained from the measurement performed by the focal plane measuring system (8). After the completion of the focusing, coordinates of various points on the substrate (5) in the alignment measuring system (9) are those of the points that have experienced the profile variation of the substrate (5). A relative positional relationship between the reticle (2) and the substrate (5) that has undergone the profile variation can be computationally derived from the changes in the coordinates of the points, and compensation can be accomplished by moving the substrate stage (4). In this way, even when there are differences between measuring focal planes of the alignment measuring system (9) and the focal plane measuring system (8), the resulting errors can be compensated for through calculation and focusing. An exposure method for a projection apparatus is also disclosed.