Schottky TFE Emission Imaging for Usable Multi-Beam Current
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Solution Overview
Problem
Schottky thermal field emission sources exhibit strong non-uniformity, making it challenging to support multi-beam applications like multi-beam lithography or inspection tools, as conventional beam-defining apertures are not applicable for high incident beam currents, and there is a need to determine the usable current and brightness for forming multi-beam flows.
Innovation Solution
A method involving high-resolution emission image acquisition and processing to compute usable beam current and brightness based on experimentally developed criteria, which includes normalizing and summing pixel data values, assigning pixel currents, and determining usable current and brightness by combining assigned pixel currents with usable current criteria, considering the temperature-dependent selection of pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a very small beam-defining aperture is used to filter the non-uniform emission, then the emission uniformity is improved, but the beam current is reduced to sub-1 μA levels
Solution Approach 1:
The patent segments the beam current into two distinct components: central beam component (usable for high-resolution imaging) and outer beam component (dog ears, suitable for multi-beam applications). This segmentation allows different parts of the emission profile to be utilized for different applications, resolving the contradiction between uniformity and total current availability.
Solution Approach 2:
The patent applies different quality criteria to different regions of the emission profile. The central region is evaluated for high-resolution imaging suitability, while the outer regions (dog ears) are evaluated for multi-beam applications. This local quality assessment allows the system to optimize for different performance requirements in different spatial regions.
2Stability of the object's composition
If a small beam-defining aperture is used to achieve uniform emission, then the emission quality is improved, but the device complexity increases due to aperture requirements
Solution Approach 1:
The patent extracts the aperture filtering function from the physical hardware and replaces it with computational algorithms. By using image processing and pixel-based current assignment, the system eliminates the need for physical beam-defining apertures, thereby reducing device complexity while maintaining emission quality control.
Solution Approach 2:
The patent replaces the mechanical aperture system with an electronic/image processing system. Instead of using physical structures to filter and define the beam, the system uses digital image acquisition, normalization, and computational algorithms to achieve the same beam definition and uniformity control, thereby eliminating mechanical complexity.
3Productivity
If the entire emitted beam is used for multi-beam formation, then the productivity is improved, but the emission quality deteriorates due to inclusion of high-divergence outer beam components
Solution Approach 1:
The patent introduces dynamic, temperature-dependent criteria for determining usable current and brightness. The usable current criteria changes based on the TFE temperature, allowing the system to adaptively optimize the balance between total current utilization and beam quality for multi-beam applications, rather than using a fixed aperture or threshold.
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 accurate evaluation of Schottky TFE usable current and brightness, optimizing operation for multi-beam electron optical tools and enabling the use of Schottky TFE sources in applications requiring high incident beam currents.
Implementation Method 1
Schottky thermal field emission (TFE) source
Data Source
AI summary
The present disclosure is related to a Schottky thermal field emission (TFE) source for emitting an electron beam. Exemplary embodiments can provide the acquisition of high-resolution emission images of Schottky TFE source and compute usable beam current and brightness based on experimentally developed usable current criteria. Advantages of these exemplary embodiments include: (1) obtaining usable beam current and brightness of a Schottky TFE source can be important with reference to Schottky TFE development and quality inspection, and (2) optimizing Schottky TFE operation modes so as to maximize Schottky TFE usable beam current and brightness can enable operation of multi-beam electron optical tools.