CPL Mask Mesa Structure Eliminates Zebra Patterning
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Solution Overview
Problem
Current chromeless phase lithography (CPL) techniques face challenges in imaging Zone 2 features due to the complexity of the zebra patterning technique, which requires high-resolution mask making and can cause issues with transmission control and reticle inspection, and there is a need for a more flexible mask design that can image critical features without relying on zebra patterns.
Innovation Solution
The method involves forming mask patterns by etching a substrate to create a mesa and depositing a chrome layer or a light transmissive phase-shifting material over the entire surface, eliminating the need for zebra patterning and allowing for improved imaging of Zone 1 and Zone 2 features using a single illumination, while also minimizing phase edge printing issues in transition regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If zebra patterning technique is used to image Zone 2 features, then imaging capability is improved, but mask making complexity increases
Solution Approach 1:
The patent extracts and eliminates the zebra patterning step from the mask making process. Instead of using complex zebra patterns to image Zone 2 features, the invention uses a simplified single-layer chrome design that directly images all zones without requiring the intermediate zebra patterning step, thereby reducing mask making complexity while maintaining imaging capability
Solution Approach 2:
The patent inverts the conventional approach by not using zebra patterning for Zone 2 features. Instead of applying the standard technique, it uses a uniform chrome layer that achieves the same imaging result through a different, simpler mechanism, effectively doing 'the other way round' to solve the contradiction
2Manufacturing precision
If zebra patterning technique is used, then transmission control is improved, but reticle inspection becomes difficult
Solution Approach 1:
The patent removes the zebra pattern structure entirely and replaces it with a uniform chrome layer. This extraction of the complex zebra structure eliminates the reticle inspection difficulties while maintaining transmission control through the simpler uniform design
Solution Approach 2:
The patent uses uniform chrome material properties to control transmission rather than relying on the complex geometric patterns of zebra structures. By controlling the chrome layer thickness and material properties, transmission is controlled without creating inspection-difficult patterns
3Adaptability or versatility
If multiple illumination sources are used to image Zone 2 and Zone 3 features, then imaging flexibility is improved, but process complexity increases
Solution Approach 1:
The patent creates a universal mask design with a single chrome layer that can image Zone 1, Zone 2, and Zone 3 features simultaneously using one illumination source. This multi-functional design eliminates the need for separate masks or multiple illumination steps, achieving imaging flexibility without increasing process complexity
Solution Approach 2:
The patent merges the imaging capability for multiple zones into a single mask structure and single illumination step. Instead of using separate masks or multiple illumination sources for different zones, the invention combines all zone imaging into one unified process, reducing complexity while maintaining flexibility
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 approach simplifies the mask making process, enhances imaging performance by reducing the complexity of mask production, and allows for effective imaging of both Zone 2 and Zone 3 features using 6% attenuated CPL and pure phase CPL features, providing improved fidelity and symmetry in aerial images.
Implementation Method 1
forming at least one of the plurality of features by etching a substrate to form a mesa and depositing a chrome layer over the entire upper surface of the mesa, where said mesa has a predetermined height
Data Source
AI summary
A method of generating a mask for printing a pattern including a plurality of features. The method includes the steps of obtaining data representing the plurality of features; and forming at least one of the plurality of features by etching a substrate to form a mesa and depositing a chrome layer over the entire upper surface of the mesa, where said mesa has a predetermined height.