Dual Reticle Exposure Layout for Higher EUV Lithography Throughput
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Solution Overview
Problem
Existing EUV lithographic apparatus face challenges in throughput and accuracy due to the need for reticle swapping and increased reduction factors, which reduce the field of view and necessitate multiple exposure steps, leading to reduced throughput and limited measurement time.
Innovation Solution
The introduction of a dual reticle support system with anamorphic imaging optics and movable object supports allows simultaneous use of two reticles, enabling efficient reticle swapping and maintaining throughput while allowing precise positioning and orientation adjustments, thus accommodating larger patterns and reducing reticle heating and particle defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single reticle is used with traditional imaging optics, then the field of view is limited and multiple reticle swaps are required, but this reduces throughput and increases measurement time
Solution Approach 1:
The patent combines multiple reticles (first and second reticles) onto a single reticle support structure, allowing both reticles to be positioned and exposed simultaneously through the same illumination region. This merging eliminates the need for reticle swapping operations and enables parallel exposure processing, directly improving throughput while reducing device complexity.
2Manufacturing precision
If the reduction factor is increased to accommodate larger patterns, then the field of view is reduced, but this necessitates multiple exposure steps and reduces throughput
Solution Approach 1:
The patent introduces anamorphic imaging optics that apply different reduction factors in different directions (first direction vs second direction). This dimensional differentiation allows the system to accommodate larger patterns in one direction while maintaining adequate field of view in the perpendicular direction, enabling single-exposure processing of previously multi-step patterns and improving throughput.
3Manufacturing precision
If reticle heating occurs during exposure, then pattern accuracy deteriorates, but this requires reduced exposure time or cooling intervals
Solution Approach 1:
The patent segments the exposure load by distributing it across multiple reticles (first and second reticles) that are exposed simultaneously. Each reticle receives a portion of the total exposure energy, reducing the thermal load on any single reticle. This segmentation prevents overheating and maintains pattern accuracy without requiring reduced exposure time or cooling intervals.
4Manufacturing precision
If particle defects occur on reticles, then exposure quality deteriorates, but this requires frequent reticle replacement or cleaning
Solution Approach 1:
The patent combines multiple reticles on a single support structure, creating redundancy in the exposure system. If particle defects occur on one reticle, the other reticle(s) can continue to provide acceptable exposure quality. This merging strategy reduces the frequency of reticle replacement or cleaning operations, maintaining exposure quality while preserving throughput.
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
This solution enhances throughput by allowing simultaneous exposure with two reticles, maintains measurement time, and reduces reticle heating and particle defects, while ensuring accurate pattern transfer on substrates.
Implementation Method 1
imaging optics configured to form an image of the first illumination region in a second illumination region
Implementation Method 2
the imaging optics is anamorphic such that a reduction factor of the image in the first direction is greater than a reduction factor of the image in a second direction that is generally perpendicular to the first direction
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An exposure apparatus comprises a first object support configured to support a first object (e.g. a reticle) and a second object support configured to support a second object (e.g. a reticle). The first and second object supports are movable relative to an illumination region. In some embodiments, imaging optics of the exposure apparatus may be anamorphic (i.e. having a reduction factor of the image(s) that is different in two different directions. In some embodiments, a gap between the first object support and the second object support may be sufficiently small that a single object may be partially supported by the first object support and partially supported by the second object support. An exposure method is disclosed in which an image is formed of each of two objects (reticles) during a single scanning exposure process.