Lithography Mark Detection System with Remote Light Detector
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Solution Overview
Problem
Existing lithography systems face challenges in accurately determining the position of a wafer with respect to the final projection system due to spatial constraints and resource limitations, particularly in vacuum chambers, leading to potential patterning errors and increased complexity.
Innovation Solution
A lithography system design that incorporates a mark position detection system with a light source, optical element, and light detector, where the light detector is positioned at a distance from the optical element and final projection system, allowing for flexible placement and minimizing thermal expansion issues, and utilizing a support system with a low thermal expansion material and flexures to maintain a stable optical path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a system for determining the position of a wafer is integrated near the final projection system, then the position detection capability is improved, but the space occupied increases and may not be available due to other subsystems
Solution Approach 1:
The light detector is positioned at a distance from the projection axis along a dimension perpendicular to the optical path, allowing the detection system to be located in available space without interfering with the compact arrangement of subsystems near the projection system
Solution Approach 2:
An optical element (such as a mirror or lens) is introduced as an intermediary to redirect the light beam from the wafer surface to the remotely positioned light detector, enabling space-efficient system architecture while maintaining detection accuracy
2Length of stationary object
If the light detector is placed close to the optical element, then the optical path length is reduced, but thermal expansion issues increase and stability decreases
Solution Approach 1:
The light detector is extracted from the immediate vicinity of the optical element and positioned at a distance, removing the source of thermal instability from the sensitive optical measurement zone while maintaining an optimized optical path through the use of an intermediary optical element
Solution Approach 2:
The mechanical constraint of fixing the light detector at a precise distance from the optical element is replaced by an optical solution using an intermediary element that can accommodate thermal expansion while maintaining optical path stability
3Measurement precision
If a large vacuum chamber is used to accommodate the position detection system, then the detection system can be properly installed, but the resource requirements and system complexity increase
Solution Approach 1:
The light detector is positioned in a different spatial dimension (at a distance from the projection axis), utilizing available space in the vacuum chamber that would otherwise be unused, thereby avoiding the need for a larger vacuum chamber
Solution Approach 2:
The optical element serves multiple functions: it maintains the optical path for position detection while also being positioned to minimize thermal expansion effects, and it enables the light detector to be located in space that does not require additional vacuum chamber volume
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 design enhances the accuracy of wafer positioning, reduces spatial requirements, and minimizes patterning errors by maintaining a stable distance between optical components, thus improving the overall efficiency and compactness of the lithography system.
Implementation Method 1
a light detector arranged for detecting a reflected light beam, wherein the reflected light beam is generated by reflection of the light beam on the target surface
Implementation Method 2
an optical element arranged for projecting said light beam on the target surface and a light detector arranged for detecting a reflected light beam
Data Source
AI summary
The invention relates to a lithography system for processing a target, wherein the lithography system comprises a final projection system arranged for projecting a pattern on the target surface. The lithography system comprises a mark position detection system arranged for detecting a position of a position mark on the target surface. The mark position detection system comprises an optical element arranged for projecting a light beam on the target surface and a light detector arranged for detecting a reflected light beam. The optical element may be positioned adjacent to the final projection system and the light detector may be positioned inside a frame.