Lithographic Alignment Correction Using Reused Substrate Data
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Solution Overview
Problem
Current lithographic processes face challenges in achieving high throughput due to extensive measurement overheads required for accurate pattern placement and overlay correction, especially as feature sizes decrease and overlay performance demands increase, leading to increased unit costs and productivity losses.
Innovation Solution
A method that combines first correction information from real-time measurements with second correction information based on prior measurements of alignment marks on similar substrates, allowing for more detailed positional corrections without the need for repeated measurements, using a combination of grid correction models and advanced alignment models to improve pattern placement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If advanced alignment models are used to measure more alignment marks for accurate overlay correction, then overlay precision is improved, but measurement time increases and productivity decreases
Solution Approach 1:
The system performs preliminary measurement of alignment marks on a first substrate to generate correction information before actual patterning. This correction information is stored and reused for subsequent substrates, eliminating the need to repeat extensive measurements on every substrate while maintaining accurate overlay correction.
Solution Approach 2:
The correction information derived from measurements on a first substrate is copied and applied to second and subsequent substrates. This allows the system to reuse alignment data across multiple substrates, significantly reducing the measurement overhead for each substrate while maintaining high overlay precision.
2Manufacturing precision
If extensive measurement operations are performed to map alignment marks across the wafer, then pattern placement accuracy is improved, but processing time increases and throughput is limited
Solution Approach 1:
The system performs comprehensive alignment mark measurements and generates correction information in advance on a first substrate before patterning. This preliminary correction information is then reused for subsequent substrates, eliminating the need to repeat time-consuming measurement operations on every substrate while maintaining accurate pattern placement.
Solution Approach 2:
The correction information obtained from extensive measurements on a first substrate is copied and applied to subsequent substrates. This copying approach allows the system to achieve accurate pattern placement without repeating the extensive measurement process on each substrate, thereby reducing measurement overhead time significantly.
3Manufacturing precision
If more alignment marks are measured to account for process-induced wafer grid deformation, then overlay performance is improved, but the complexity and time of measurement operations increase
Solution Approach 1:
The system performs comprehensive measurements of multiple alignment marks across the wafer to capture process-induced grid deformations in advance. The correction information derived from these measurements is stored and reused for subsequent substrates, eliminating the need to repeat complex measurement operations while maintaining high overlay performance.
Solution Approach 2:
The correction information that accounts for process-induced wafer grid deformation, derived from measuring multiple alignment marks on a first substrate, is copied and applied to subsequent substrates. This approach maintains high overlay performance without repeating the complex measurement process on each substrate.
Data Source
AI summary
A substrate is loaded onto a substrate support of a lithographic apparatus, after which the apparatus measures locations of substrate alignment marks. These measurements define first correction information allowing the apparatus to apply a pattern at one or more desired locations on the substrate. Additional second correction information is used to enhance accuracy of pattern positioning, in particular to correct higher order distortions of a nominal alignment grid. The second correction information may be based on measurements of locations of alignment marks made when applying a previous pattern to the same substrate. The second correction information may alternatively or in addition be based on measurements made on similar substrates that have been patterned prior to the current substrate.