Dual-Stage Lithography Positioning System Throughput Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithographic apparatuses face throughput penalties due to the need for referencing or zeroing of incremental position measurement systems, which requires positioning the object table to a dedicated reference location, especially in multistage systems where accurate absolute positioning of multiple substrate tables is necessary.
Innovation Solution
A dual-stage positioning system that uses a first position measurement system to provide incremental and absolute position measurements of both object tables, allowing the second object table's absolute position to be determined relative to the reference based on the absolute position of the first object table and their distance, eliminating the need for the second object table to be positioned at a dedicated reference location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an incremental position measurement system is used to measure the position of object tables, then the system complexity is reduced and cost is lowered, but the system requires periodic referencing or zeroing that causes throughput penalties
Solution Approach 1:
The system performs referencing or zeroing of the incremental position measurement system in advance, before the object table needs to be positioned for measurement. By pre-positioning the object table to the reference location and establishing the zero point beforehand, the system eliminates the need for interrupting measurement operations to perform referencing, thus maintaining high throughput while using a simpler incremental measurement system
Solution Approach 2:
A reference object or reference mark is introduced as an intermediary element that facilitates the referencing process. This reference object serves as a fixed reference point that the incremental position measurement system can align with to establish absolute position information, enabling the system to maintain both simplicity and continuous operation
2Measurement precision
If referencing requires positioning the object table to a dedicated reference location, then absolute position measurement can be obtained, but the positioning time is increased and throughput is reduced
Solution Approach 1:
The object table is positioned to the reference location in advance, before the actual measurement process begins. This preliminary positioning and referencing action ensures that the incremental position measurement system is properly zeroed and calibrated before measuring the position of the second object table, thereby obtaining accurate absolute position information without time loss during the measurement process
Solution Approach 2:
The system uses the position information of the first object table (which has been referenced) as a reference to determine the absolute position of the second object table. By copying or transferring the reference framework from the first table to the second table, the system avoids the need to physically move the second table to a separate reference location, thus reducing positioning time while maintaining measurement accuracy
3Productivity
If a dual-stage system with multiple object tables is used to increase productivity, then more substrates can be processed in parallel, but the positioning complexity and referencing requirements increase
Solution Approach 1:
The system merges the positioning and referencing operations for multiple object tables into a unified process. By using the first object table as a reference for the second object table, the system combines what would otherwise be separate referencing operations into a single integrated process, reducing the overall complexity of managing multiple tables while maintaining high productivity
Solution Approach 2:
The first object table serves multiple functions: it is both a processing table for substrates and a reference table for positioning the second object table. This multi-functionality reduces the need for separate reference tables or additional reference marks, simplifying the overall positioning system while enabling dual-stage processing for increased throughput
Data Source
AI summary
A positioning system for positioning an object in a lithographic apparatus, including: a first and second object tables moveable in an operating area; a first position measurement system to provide an incremental position measurement of the second object table relative to a reference when in the operating area, wherein the first position measurement system is configured to provide an absolute position measurement of the first object table relative to the reference; a second position measurement system to provide an absolute position measurement of the first object table relative to the second object table, and wherein the first position measurement system is further configured to provide an absolute position measurement of the second object table relative to the reference based on the absolute position measurement of the first object table relative to the reference and on the absolute position measurement of the first object table relative to the second object table.