Complementary E-Beam Lithography for Via Precision
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Solution Overview
Problem
Current lithographic technologies face challenges in scaling via features to smaller sizes due to limitations in overlay control, critical dimension resolution, and line width roughness, particularly as via pitches decrease, leading to increased fabrication costs and potential inability to print via openings with conventional scanners.
Innovation Solution
The implementation of complementary e-beam lithography (CEBL) combines optical lithography with e-beam lithography to pattern critical layers, using pitch division techniques and electron beam direct write to 'cut' lines, enabling improved throughput and precision in high-volume manufacturing environments through advanced alignment methods, data compression, and staggered aperture arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic scanners are used to pattern small vias, then overlay control and critical dimension resolution are limited, but fabrication costs increase and manufacturing precision deteriorates
Solution Approach 1:
The patent segments the lithographic process into two distinct steps: first using optical lithography to create initial via openings at relaxed pitch, then using e-beam lithography to precisely trim and adjust the critical dimensions. This segmentation allows each process to operate in its optimal performance range, achieving high precision without proportionally increasing overall cost.
Solution Approach 2:
The optical lithography step performs preliminary patterning to create via openings that are larger than the final target dimensions. This preliminary action establishes the basic via locations and removes material, so that the subsequent e-beam step only needs to perform precise trimming, reducing the complexity and cost of the high-precision operation.
2Quantity of substance
If via pitch is decreased to increase density, then functional unit density increases, but overlay control tolerance requirements become more stringent
Solution Approach 1:
The patent separates the via formation process into initial optical lithography patterning followed by e-beam trimming. This segmentation allows the optical step to handle the challenging small pitch layout while the e-beam step independently achieves the required overlay precision, decoupling the density requirement from the overlay tolerance requirement.
Solution Approach 2:
The patent changes the operational parameters between the two lithographic steps: optical lithography operates at relaxed pitch with larger features, while e-beam lithography operates at the final small pitch with precise dimensional control. This parameter change allows the system to achieve high via density without proportionally tightening overlay tolerances across the entire process.
3Manufacturing precision
If e-beam lithography is used for high-volume manufacturing, then precision improves, but throughput must be improved to be economically viable
Solution Approach 1:
The patent applies e-beam lithography partially, using it only for the trimming step rather than the entire via formation process. This partial application allows the high-precision e-beam process to be used only where necessary, while the majority of the patterning work is done by faster optical lithography, improving overall throughput while maintaining precision.
Solution Approach 2:
The patent segments the lithographic workflow so that optical lithography handles the bulk material removal and initial patterning at high speed, while e-beam lithography handles only the final precision trimming. This segmentation optimizes throughput by assigning each process its most suitable task based on speed and precision characteristics.
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 allows for cost-effective patterning of critical layers at advanced technology nodes, extending the use of current optical lithography technology, and enables the use of e-beam lithography in high-volume manufacturing by improving throughput and precision, addressing the challenges of small via pitches and critical dimension resolution.
Implementation Method 1
electron beam direct write to 'cut' lines
Data Source
AI summary
Lithographic apparatuses suitable for, and methodologies involving, complementary e-beam lithography (CEBL) are described. In an example, a blanker aperture array (BAA) for an e-beam tool includes a first column of openings along a first direction, each of the openings of the first column of openings having dog-eared corners. The BAA also includes a second column of openings along the first direction and staggered from the first column of openings, each of the openings of the second column of openings having dog-eared corners. The first and second columns of openings together form an array having a pitch in the first direction. A scan direction of the BAA is along a second direction, orthogonal to the first direction. The pitch of the array corresponds to half of a minimal pitch layout of a target pattern of lines for orientation parallel with the second direction.