EUV Lithography Distortion Matching via Scan Trajectory Control
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Solution Overview
Problem
Next-generation lithography systems face challenges in accurately overlaying new patterns of densely packed parallel lines onto semiconductor workpieces with existing distorted patterns, due to factors like temperature changes, residual stress, and irregularities in the projection optical assembly.
Innovation Solution
An extreme ultraviolet lithography system that adjusts the scan trajectory, magnification, and magnification tilt of the patterning element pattern during scanning to accurately overlay new patterns of densely packed parallel lines onto workpieces with existing distorted patterns, using a control system that moves the workpiece relative to the exposure field along specific trajectories and adjusts EUV illumination to expose every other die in alternating passes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography systems are used to pattern densely packed parallel lines, then manufacturing capability is maintained, but manufacturing precision deteriorates due to distortion errors in overlaying new patterns onto existing distorted patterns
Solution Approach 1:
The control system pre-calculates and stores correction values for scan trajectory, magnification, and magnification tilt based on measured distortion characteristics of the workpiece or substrate. Before actual patterning, the system loads these pre-computed correction parameters to compensate for expected distortions, enabling accurate overlay without real-time complex calculations
Solution Approach 2:
The system dynamically adjusts scan trajectory, magnification, and magnification tilt parameters during the patterning process based on position-dependent distortion characteristics. The control system modifies these parameters in real-time as the stage moves through different regions of the workpiece, allowing the system to adapt to local distortion variations and maintain alignment precision across the entire substrate
2Manufacturing precision
If the scan trajectory is adjusted to match distorted existing patterns, then manufacturing precision improves, but device complexity increases due to additional control parameters and trajectories
Solution Approach 1:
Distortion characteristics are measured and characterized in advance, and correction trajectories are pre-computed before production. The control system stores these pre-calculated scan trajectories and correction parameters, eliminating the need for complex real-time distortion calculations during actual patterning operations
Solution Approach 2:
The control system creates a digital model or map of the distortion characteristics based on measurements, and uses this copied distortion map to generate corrected scan trajectories. This virtual model allows the system to compensate for physical distortions through software-based trajectory adjustments without modifying the physical optical path
3Manufacturing precision
If magnification and magnification tilt are adjusted during scanning, then manufacturing precision improves, but ease of operation deteriorates due to additional control parameters
Solution Approach 1:
The control system pre-calculates the required magnification and magnification tilt corrections based on position-dependent distortion characteristics. These correction parameters are stored and automatically applied during scanning, eliminating the need for operators to manually adjust multiple magnification parameters during operation
Solution Approach 2:
The control system automatically determines and applies the appropriate magnification and magnification tilt corrections based on the current stage position and pre-stored distortion correction data. The system self-adjusts these parameters without requiring manual intervention, maintaining operational simplicity while achieving high precision overlay
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
The system effectively matches and overlays new patterns of densely packed parallel lines onto distorted existing patterns, improving alignment and reducing distortion errors, thereby enhancing the precision of semiconductor fabrication.
Implementation Method 1
a projection optical assembly that directs the extreme ultraviolet beam diffracted off of the patterning element at the workpiece
Data Source
AI summary
An extreme ultraviolet lithography system (10) that creates a new pattern (330) having a plurality of densely packed parallel lines (332) on a workpiece (22), the system (10) includes a patterning element (16); an EUV illumination system (12) that directs an extreme ultraviolet beam (13B) at the patterning element (16); a projection optical assembly (18) that directs the extreme ultraviolet beam diffracted off of the patterning element (16) at the workpiece (22) to create a first stripe (364) of generally parallel lines (332) during a first scan (365); and a control system (24). The workpiece (22) includes an existing pattern (233) that is distorted. The control system (24) selectively adjusts a control parameter during the first scan (365) so that the first stripe (364) is distorted to more accurately overlay the portion of existing pattern (233) positioned under the first stripe (364).