Charged Particle Lithography Aperture Array Beam Control
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Solution Overview
Problem
Current charged particle lithography systems face challenges in achieving high resolution and throughput due to spherical and chromatic aberrations in electrostatic lenses, which limit their ability to reduce critical dimensions and increase the number of beamlets, leading to increased interactions and loss of resolution.
Innovation Solution
A charged particle system with a converging means comprising a first electrode and an aperture array element forming a second electrode, creating an accelerating electric field to reduce aberrations, allowing for increased field size and improved beam control, including the use of an Einzel lens and curved surfaces to further optimize beamlet formation and reduce aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the current in the charged particle beam is increased to achieve higher throughput, then the throughput increases, but the interactions between charged particles increase leading to loss of resolution
Solution Approach 1:
The patent divides the charged particle beam into multiple parallel beamlets using an aperture array, which distributes the total current across many smaller beams. This segmentation reduces the current density in each beamlet, minimizing charged particle interactions and maintaining resolution while achieving high throughput through parallel processing of multiple beamlets simultaneously
2Manufacturing precision
If the field size of the system is increased to reduce interactions between charged particles, then the resolution is maintained, but the spherical and chromatic aberrations in electrostatic lenses increase
Solution Approach 1:
The patent extracts the collimation function from traditional electrostatic lenses and implements it using a combination of a collimator and an aperture array. This separation removes the spherical and chromatic aberrations inherent in electrostatic lenses while maintaining the ability to create parallel beamlets across a large field size, thus preserving both resolution and image quality
3Manufacturing precision
If the number of beamlets is massively increased to reduce critical dimensions, then the throughput is maintained, but the device complexity and cost increase
Solution Approach 1:
The patent combines the collimation and beamlet formation functions into a single integrated optical path using a collimator followed by an aperture array. This merging eliminates the need for complex individual control systems for each beamlet while maintaining precise control over the beamlet pattern, thereby reducing device complexity and cost while achieving the required critical dimensions
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 significantly reduces aberrations, enabling higher throughput and smaller critical dimensions while maintaining image quality, allowing for the creation of multiple parallel beamlets with improved uniformity and reduced interactions, thus addressing the limitations of existing systems.
Implementation Method 1
an aperture array element comprising a plurality of apertures, included so as to form a second electrode, adapted for creating an electric field between the first electrode and the second electrode
Implementation Method 2
a converging means for refracting said diverging charged particle beam
Data Source
AI summary
A charged particle lithography system for transferring a pattern onto the surface of a target, such as a wafer, comprising a charged particle source adapted for generating a diverging charged particle beam, a converging means for refracting said diverging charged particle beam, the converging means comprising a first electrode, and an aperture array element comprising a plurality of apertures, the aperture array element forming a second electrode, wherein the system is adapted for creating an electric field between the first electrode and the second electrode.