Aperture Stop Arrays for Pupil Tuning in Exposure Systems
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Solution Overview
Problem
Existing position detection apparatuses in exposure systems face challenges in achieving high overlay accuracy and reducing resolvable line width due to complex and costly aperture stop driving mechanisms, which complicate tuning and affect image quality, especially when switching between different illumination methods.
Innovation Solution
A position detection apparatus with a simplified aperture stop switching mechanism, featuring a first array of aperture stops in the illumination optical system and a second array in the detection optical system, each with a dedicated driving mechanism to fine-tune the aperture stops along specific directions, allowing for efficient pupil position tuning without additional mechanical complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a position detection apparatus includes aperture stop driving mechanisms with two tuning axes in both illumination and detection optical systems, then the pupil can be tuned in multiple directions, but the driving mechanism becomes complicated and costly
Solution Approach 1:
The pupil tuning function is segmented between two independent components: the illumination optical system's aperture stop (controlling one direction) and the detection optical system's aperture stop (controlling the other direction). This segmentation allows each system to have a simpler single-axis driving mechanism rather than requiring complex two-axis mechanisms in each system.
Solution Approach 2:
Both aperture stops serve dual purposes: they control the respective optical systems' light paths and collectively provide two-dimensional pupil tuning capability when combined. This multi-functionality eliminates the need for separate dedicated tuning mechanisms for each direction.
2Manufacturing precision
If aperture stop driving mechanisms are added to enable precise pupil tuning, then overlay accuracy can be improved, but the arrangement becomes complicated and affects tuning accuracy
Solution Approach 1:
The tuning function is divided between illumination and detection systems, with each handling one aperture stop. This segmentation simplifies the mechanical arrangement in each system while maintaining the ability to achieve high overlay accuracy through coordinated control of both aperture stops.
3Measurement precision
If multiple aperture stops are arranged in arrays with driving mechanisms, then pupil position can be fine-tuned in specific directions, but the switching mechanism becomes more complex
Solution Approach 1:
The aperture stop arrays are segmented into two independent groups: one in the illumination system and one in the detection system. Each array is driven independently along its specific direction, simplifying the switching mechanism compared to a single complex array requiring multi-axis control.
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 overlay accuracy and reduces costs by simplifying the aperture stop tuning process, improving image quality and compatibility with various illumination methods, thereby supporting high-precision position detection in exposure systems.
Implementation Method 1
an illumination optical system configured to illuminate a target
Implementation Method 2
a detection optical system configured to form an image of the target illuminated with light from the illumination optical system on a light-receiving surface of the photoelectric converter
Implementation Method 3
a photoelectric converter
Data Source
AI summary
Position detection apparatus includes illumination optical system for illuminating target, detection optical system for forming image of the illuminated target illuminated on photoelectric converter, first array having first aperture stops, second array having second aperture stops, first driving mechanism for arranging the selected first aperture stop on pupil of the illumination optical system by driving the first array such that first aperture stop crossing optical axis of the illumination optical system moves in first direction, second driving mechanism for arranging the selected second aperture stop on pupil of the detection optical system by driving the second array such that second aperture stop crossing optical axis of the detection optical system moves in second direction. The first and second driving mechanisms fine-tune positions of the selected first and second aperture stops in the first and second directions, respectively.