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 and residual stress, which affect the precision and alignment of the pattern transfer process.
Innovation Solution
An extreme ultraviolet lithography system that adjusts the scan trajectory, magnification, and magnification tilt of the patterning element pattern during exposure to accurately overlay the new pattern onto the existing distorted pattern on the workpiece, utilizing a control system to manage the movement of the workpiece and EUV illumination system to ensure precise alignment and matching of the new pattern with the existing one.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography systems are used to transfer patterns onto workpieces, then the pattern transfer process is simple, but the alignment accuracy deteriorates due to workpiece distortion from temperature changes and residual stress
Solution Approach 1:
The system performs preliminary actions by measuring the workpiece distortion before pattern transfer and calculating the required scan trajectory adjustments in advance. This allows the system to compensate for distortion proactively rather than reactively, improving alignment accuracy while maintaining operational simplicity
Solution Approach 2:
The system changes the scan trajectory parameters dynamically based on measured workpiece distortion. By adjusting scan position, speed, and acceleration as functions of workpiece coordinates, the system compensates for thermal and stress-induced distortion, achieving high alignment accuracy without increasing overall system complexity
2Manufacturing precision
If the scan trajectory is adjusted to compensate for workpiece distortion, then the alignment accuracy improves, but the control complexity increases
Solution Approach 1:
The system implements feedback by measuring actual workpiece distortion and using this information to adjust scan trajectory parameters. This closed-loop approach ensures high overlay accuracy while keeping control complexity manageable through automated calculation of correction trajectories based on measured distortion
Solution Approach 2:
The control system performs preliminary calculation of the corrected scan trajectory before actual pattern transfer. By pre-computing the optimal scan path that compensates for distortion, the system achieves high overlay accuracy without requiring complex real-time control adjustments during scanning
3Manufacturing precision
If the magnification and magnification tilt are adjusted during exposure, then the pattern alignment improves, but the device complexity increases
Solution Approach 1:
The system applies dynamic adjustments to magnification and magnification tilt parameters during the exposure process. By making these parameters variable rather than fixed, the system can compensate for workpiece distortion and achieve improved pattern alignment while using standard lithography equipment
Solution Approach 2:
The system changes magnification and magnification tilt parameters as functions of workpiece position and distortion characteristics. This allows precise pattern alignment on distorted workpieces by locally adjusting optical parameters without requiring complex additional hardware
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 the new pattern of densely packed parallel lines onto the workpiece, improving the accuracy and alignment with the existing pattern, even in the presence of distortion, by dynamically adjusting the scan trajectory and magnification parameters, thereby enhancing the precision of the lithography process.
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).