Lithography Chuck Alignment Using Position Marks
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Solution Overview
Problem
Existing lithography systems face challenges in determining the position of a wafer with respect to the final projection system with high reproducibility, particularly when the wafer needs to be removed and repositioned between pattern projection sessions.
Innovation Solution
The implementation of a method and system that uses a chuck with position marks and alignment sensors arranged along perpendicular axes to detect and align the chuck position marks quickly and accurately, utilizing interferometers and level sensors for precise positioning and orientation measurement, enabling faster and more reliable alignment of the wafer with respect to the patterning beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wafer position is determined using conventional methods at the beginning of each session, then the position can be measured, but the reproducibility of wafer positioning is poor
Solution Approach 1:
The system performs preliminary alignment by detecting chuck position marks before pattern projection sessions. The alignment sensing system measures the chuck position relative to the beam grid and stores this information for later use, enabling rapid repositioning without full realignment when the wafer is removed and returned.
Solution Approach 2:
The system creates a reference copy of the chuck position relationship by detecting position marks on the chuck and storing the measured coordinates. This reference data is then used to quickly restore the chuck position without requiring complete realignment procedures, improving reproducibility.
2Adaptability or versatility
If the wafer is removed and repositioned between pattern projection sessions, then different patterns can be processed, but the alignment time and positioning accuracy are reduced
Solution Approach 1:
The system performs preliminary measurement of chuck position marks and stores reference data before wafer removal. When the wafer is returned, the system uses this pre-stored reference information to rapidly reposition the chuck, minimizing alignment time and enabling quick switching between different pattern processing sessions.
3Adaptability or versatility
If the wafer is removed and repositioned between pattern projection sessions, then different patterns can be processed, but the positioning reproducibility is reduced
Solution Approach 1:
The system creates and stores a reference copy of the chuck position relationship by detecting position marks. This reference data serves as a template for reproducing the correct chuck position, ensuring high positioning reproducibility when the wafer is removed and returned for different pattern processing sessions.
4Measurement precision
If conventional alignment methods are used to determine wafer position, then the position can be measured, but the speed of positioning is reduced
Solution Approach 1:
The system performs preliminary detection of chuck position marks and stores reference coordinates before pattern projection. When repositioning is needed, the system uses this pre-stored reference data to rapidly calculate and execute the required chuck movement, significantly increasing positioning speed while maintaining measurement precision.
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 enhances the reproducibility and speed of wafer positioning, allowing for more efficient and accurate alignment of the chuck and patterning beam, thereby improving the overall lithography process.
Implementation Method 1
an alignment sensing system arranged for detecting the first and second chuck position marks, the alignment sensing system comprising at least a first alignment sensor and a second alignment sensor
Implementation Method 2
an optical system arranged for focusing the alignment light beam on the surface and for guiding the reflected alignment light beam on the light intensity detector
Implementation Method 3
utilizing interferometers and level sensors for precise positioning and orientation measurement
Implementation Method 4
utilizing interferometers and level sensors for precise positioning and orientation measurement
Data Source
AI summary
A method for operating a target processing system for processing a target (23) on a chuck (13), the method comprising providing at least a first chuck position mark (27) and a second chuck position mark (28) on the chuck (13); providing an alignment sensing system (17) arranged for detecting the first and second chuck position marks (27, 28), the alignment sensing system (17) comprising at least a first alignment sensor (61) and a second alignment sensor (62); moving the chuck (13) to a first position based on at least one measurement of the alignment sensing system (17); and measuring at least one value related to the first position of the chuck.