Topography Measurement System Alignment Parameter Determination
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Solution Overview
Problem
Current lithographic apparatuses rely on limited alignment marks for accurate pattern projection onto substrates, which restricts the number of alignment points that can be measured, leading to potential inaccuracies and increased processing time.
Innovation Solution
A system that uses a topography measurement system to determine height maps across multiple locations on a substrate, allowing for the calculation of alignment parameters by comparing these maps to reference height maps, thereby enabling more precise alignment without relying solely on alignment marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment marks are used for alignment measurement, then alignment can be performed, but the number of measurable alignment points is limited and processing time increases
Solution Approach 1:
The invention extracts the alignment measurement function from the dedicated alignment mark system and relocates it to the topography measurement system. By using the topography measurement system's height data to determine alignment parameters, the patent eliminates the need for separate alignment marks, thereby increasing the number of measurable points and reducing processing time while maintaining measurement precision
Solution Approach 2:
The topography measurement system is given a dual function: it continues to measure substrate topography while also determining alignment parameters. This multi-functionality allows the same measurement system to perform both tasks, increasing the number of measurement points from the limited alignment marks to the numerous topography measurement points, thus improving efficiency without sacrificing precision
2Measurement precision
If more alignment marks are placed on the substrate to increase measurement points, then alignment accuracy improves, but substrate real estate is reduced and device complexity increases
Solution Approach 1:
The invention removes the dedicated alignment marks from the substrate and extracts their measurement function to the topography measurement system. This eliminates the need for additional substrate real estate to be dedicated to alignment marks, while still providing sufficient measurement points through the topography data
Solution Approach 2:
The topography measurement system serves multiple purposes: it measures substrate topography for focus control and simultaneously provides alignment parameter determination. This multi-functionality allows alignment measurement without requiring additional alignment marks, preserving substrate real estate while maintaining measurement precision
3Measurement precision
If a separate alignment system is used in addition to topography measurement, then alignment accuracy is maintained, but device complexity and processing time increase
Solution Approach 1:
The topography measurement system is configured to perform dual functions: measuring substrate topography and determining alignment parameters. By making the same system multi-functional, the patent eliminates the need for a separate alignment system, reducing device complexity and processing time while maintaining alignment measurement precision through the height data analysis
Solution Approach 2:
The invention merges the alignment measurement function with the topography measurement system. Instead of having separate systems for topography and alignment measurements, the patent combines these functions into a single integrated approach, reducing system complexity and the number of processing steps while maintaining measurement accuracy
Data Source
AI summary
A system comprises a topography measurement system configured to determine a respective height for each of a plurality of locations on a substrate; and a processor configured to: determine a height map for the substrate based on the determined heights for the plurality of locations; and determine at least one alignment parameter for the substrate by comparing the height map and a reference height map, wherein the reference height map comprises or represents heights for a plurality of locations on a reference substrate portion.