Reticle Assembly for Simultaneous Multi-Field Lithography
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Solution Overview
Problem
Conventional lithographic apparatuses face inefficiencies in throughput due to the time required for deceleration and acceleration of scanning movements, which limits the exposure of image fields on substrates during the lithographic process.
Innovation Solution
A reticle assembly is used to project two image fields onto a substrate in a single scanning movement by aligning a first reticle with a first image field and a second reticle with a second image field such that the distance between them corresponds to the distance between target portions on the substrate, allowing for simultaneous exposure of multiple target portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the substrate table and patterning device support are scanned in opposite directions to expose multiple target portions, then the coverage area is increased, but the deceleration and acceleration time between scans increases, reducing throughput
Solution Approach 1:
The reticle is divided into multiple reticles, each containing a specific image field corresponding to a target portion on the substrate. This segmentation allows each reticle to be scanned independently in a single direction, eliminating the need for opposite-direction scanning and reducing deceleration/acceleration time between scans.
Solution Approach 2:
The patent introduces a spatial arrangement dimension by positioning multiple reticles at different locations on the reticle support. This allows the system to cover multiple target portions by having reticles arranged in a configuration that corresponds to their positions on the substrate, enabling simultaneous exposure without changing scan direction.
2Productivity
If larger reticles are used to expose multiple target portions, then the number of exposed target portions increases, but the reticle size specifications are limited, restricting further increases
Solution Approach 1:
Instead of using a single large reticle, the system segments the patterning function into multiple smaller reticles. Each reticle contains an image field for a specific target portion, and the reticle support holds these reticles in positions that correspond to their target portions on the substrate. This segmentation approach allows exposing multiple target portions without requiring a single oversized reticle.
Solution Approach 2:
Multiple reticles are combined on a single reticle support in a coordinated arrangement. The reticle support positions and orients these separate reticles so that during a single scanning movement, each reticle's image field is projected onto its corresponding target portion, achieving the functionality of a large reticle without the size constraints.
3Adaptability or versatility
If the substrate table is decelerated and accelerated between scanning movements, then the scanning direction can be changed, but the time lost during deceleration and acceleration reduces the effective exposure time
Solution Approach 1:
The scanning process is segmented into independent movements for each reticle. Each reticle is scanned from its starting position to its ending position in a single direction without requiring reversal. The reticle support and substrate table move synchronously, and each reticle's image field is projected onto its corresponding target portion during this unidirectional scan, eliminating the need for deceleration and acceleration between scans.
Data Source
AI summary
A reticle assembly for use in a lithographic process in which a first image field and a second image field are projected onto a first target portion and a second target portion on a substrate, the reticle assembly being arranged to hold a first reticle having the first image field and a second reticle having the second image field such that a distance between the first and second image fields substantially corresponds to a distance between the first and the second target portions. Embodiments also relate to a lithographic apparatus including the reticle assembly, the use in a lithographic process in which a first image field and a second image field are projected onto a first target portion and a second portion on a substrate, of a first reticle having the first image field and a second reticle having the second image field, wherein a distance between the first and second image fields substantially corresponds to a distance between the first and second target portions.