Absorbing Conducting Underlayer for Ebeam Direct Write Lithography
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Solution Overview
Problem
Current lithographic technologies face challenges in achieving precise overlay control and resolution for extremely small via pitches in integrated circuits, with limitations in critical dimension scaling, line width roughness, and critical dimension uniformity, especially as feature sizes decrease beyond the capabilities of conventional scanners.
Innovation Solution
Implementing an underlying absorbing and/or conducting layer in e-beam direct write lithography to reduce backscattered electrons, thereby improving image contrast, resolution, and critical dimension uniformity, and enabling more precise patterning of small features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic scanners are used to pattern small vias, then existing manufacturing processes can be maintained, but resolution and critical dimension uniformity deteriorate as feature sizes decrease
Solution Approach 1:
An underlying absorbing or conducting layer is introduced as an intermediary between the substrate and the photoresist. This layer absorbs backscattered electrons, preventing them from degrading the aerial image and compromising critical dimension uniformity, thereby enabling high-precision patterning of small features
Solution Approach 2:
The electron beam energy parameters are optimized (e.g., 30-100 keV range) and the properties of the underlying layer are controlled (thickness, material composition) to maximize backscatter absorption while maintaining resolution, allowing conventional scanners to achieve improved manufacturing precision
2Manufacturing precision
If multiple lithographic masks are used to achieve small via pitches, then resolution requirements are met, but fabrication costs increase
Solution Approach 1:
The underlying absorbing layer serves as a universal mediator that improves the performance of conventional lithographic scanners, enabling them to directly pattern small via pitches without requiring multiple masks, thereby reducing fabrication complexity and cost
3Manufacturing precision
If e-beam lithography is used to improve resolution, then manufacturing precision improves, but backscattered electrons reduce image contrast
Solution Approach 1:
The harmful backscattered electrons are converted into a beneficial effect by introducing an underlying absorbing layer that selectively absorbs these electrons, transforming the degradation mechanism into an improved aerial image with higher contrast and better-defined features
Solution Approach 2:
The underlying layer acts as a mediator that interacts with backscattered electrons to absorb them, preventing the loss of image contrast and enabling high-resolution e-beam lithography
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
The use of an absorbing and/or conducting underlayer enhances the resolution and throughput of e-beam lithography, allowing for improved feature density and reduced costs in high-volume manufacturing by minimizing backscatter effects and maintaining high contrast during exposure.
Implementation Method 1
backscattered electrons reduce the contrast of the aerial image formed during exposure
Implementation Method 2
The underlying layer absorbs, reflects or conducts away incident electrons to diminish backscatter
Implementation Method 3
performing ebeam direct write lithography to pattern the resist layer with incident electrons
Data Source
AI summary
Lithographic apparatuses suitable for, and methodologies involving, complementary e-beam lithography (CEBL) are described. Particular embodiments are directed to implementation of an underlying absorbing and/or conducting layer for ebeam direct write (EBDW) lithography.