Patterned Aperture for High Current Density Electron Beam Lithography
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Solution Overview
Problem
Current electron lithography systems face challenges in achieving high throughput, precise patterning of small critical dimensions, and reliable operation due to limitations in beam positioning and shaping strategies, which affect the semiconductor industry's need for efficient mask and reticle writing as well as direct wafer writing.
Innovation Solution
A charged particle optical apparatus that generates a high current density shaped beam using a patterned beam-defining aperture (PBDA) within a charged particle optical column, optimizing beam shape and position to achieve improved current profile edge sharpness and uniformity, reducing complexity and increasing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Gaussian beams are used to achieve high current density, then beam current density is improved, but beam shape control and edge sharpness deteriorate due to long current tails
Solution Approach 1:
The patent segments the beam current distribution by introducing a patterned beam-defining aperture that divides the Gaussian beam into a central high-current region and blocked tail regions. The aperture transmits only the central portion of the beam, creating a shaped beam with suppressed tails while maintaining high current density in the transmitted region.
Solution Approach 2:
The patent applies local quality by creating a non-uniform beam profile where the central region maintains high current density while the tail regions are suppressed. The patterned aperture selectively transmits different portions of the beam, creating locally optimized current distribution that balances high current density with improved edge sharpness.
2Manufacturing precision
If shaped beams are formed using multiple apertures and deflectors, then beam shape control is improved, but device complexity increases
Solution Approach 1:
The patent merges the beam shaping function into a single patterned beam-defining aperture located at the source plane, eliminating the need for multiple separate shaping apertures and deflectors. This consolidation achieves the desired beam shape while significantly reducing the complexity of the optical column.
Solution Approach 2:
The patent extracts the beam shaping function from the intermediate optical elements and relocates it to the source plane aperture. By taking out the shaping requirement from the complex optical path and implementing it at the source, the system achieves simplified design with fewer components.
3Manufacturing precision
If shaped beams with reduced current tails are used, then patterning precision is improved, but beam current density decreases
Solution Approach 1:
The patent employs dynamic beam shaping by using a programmable spatial light modulator that can adaptively adjust the aperture pattern. This allows the system to dynamically optimize the balance between current density and edge sharpness based on the specific patterning requirements, rather than using a fixed aperture design.
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 solution enables high current density beams with improved edge sharpness and uniformity, enhancing writing throughput and reliability in lithography applications while simplifying the electron optical design, thus addressing the industry's needs for precise and efficient patterning.
Implementation Method 1
a charged particle source emits a diverging beam of charged particles which are then formed into a roughly parallel charged particle beam by the first lens. The second lens then focuses the roughly parallel charged particle beam onto the surface of a substrate
Implementation Method 2
a patterned beam-defining aperture which can be customized for insertion at various positions in the column... it should transmit a large portion of charged particles in the beam which would fall within the predetermined beam shape, and (2) it should block transmission of a large portion of charged particles in the beam which would fall outside the predetermined beam shape
Data Source
AI summary
A direct-write electron beam lithography system employing a patterned beam-defining aperture to enable the generation of high current-density shaped beams without the need for multiple beam-shaping apertures, lenses and deflectors is disclosed. Beam blanking is accomplished without the need for an intermediate crossover between the electron source and the wafer being patterned by means of a double-deflection blanker, which also facilitates proximity effect correction. A simple type of “moving lens” is utilized to eliminate off-axis aberrations in the shaped beam. A method for designing the patterned beam-defining aperture is also disclosed.