Multiple-Column Electron Beam Apparatus Using Magnetic Lensing
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Solution Overview
Problem
Single electron beam systems are slow due to low throughput at high resolution and suffer from cross talk between adjacent electron-optical columns, while previous multi-beam systems with electrostatic elements are prone to substantial aberrations.
Innovation Solution
A design that converts a large-scale magnetic field into multiple lensing fields to focus electron beams simultaneously without cross talk, using a magnetic block with bores to produce lenses at both ends of each column, and electrostatic elements for rastering and energy control, with a homogeneous magnetic field containing secondary electrons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single electron beam system is used, then cross talk between adjacent columns is avoided, but throughput is low and speed is slow
Solution Approach 1:
The system divides a single electron beam into multiple parallel beams (e.g., 64 beams) by using a beam splitter and array of microlenses. Each beam is directed to a different location on the substrate, enabling simultaneous inspection of multiple areas. This segmentation approach maintains the advantage of independent beam paths (no cross-talk) while achieving N-fold improvement in throughput.
2Productivity
If a parallel multi-beam system is used, then throughput is improved, but cross talk between adjacent columns occurs
Solution Approach 1:
The electron beam is segmented into multiple spatially separated beams using a beam splitter and microlens array. Each beam travels through its own optical path to a distinct location on the substrate, physically isolating the beams and eliminating cross-talk between adjacent columns while maintaining high throughput.
Solution Approach 2:
A beam splitter and array of microlenses are introduced as intermediary components to distribute the single electron beam into multiple independent beams. These intermediaries ensure that each beam is properly directed and isolated, preventing cross-talk while achieving parallel processing capability.
3Device complexity
If purely electrostatic elements are used in multi-beam systems, then device complexity is reduced, but substantial aberrations occur
Solution Approach 1:
The system changes the fundamental parameter of field type from purely electrostatic to magnetic. Magnetic fields are used to focus and control the electron beams, which reduces spherical aberrations and improves focus precision. This parameter change allows for better beam control while maintaining manageable device complexity through the use of standard magnetic lens components.
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 significantly improves throughput by eliminating cross talk and aberrations, allowing for efficient and precise inspection and lithography with negligible signal contamination.
Implementation Method 1
The optical system comprises a magnetic lens surrounding an array of electron beam columns
Implementation Method 2
electrostatic elements for rastering and energy control
Data Source
AI summary
One embodiment disclosed relates an apparatus which includes an electromagnet arranged to provide a large-scale magnetic field in a region. The apparatus further includes an array of multiple electron beam columns formed in the region using an array of bores through magnetic material. Another embodiment relates to a method of generating an array of electron beams. A large-scale magnetic field is generated in a region using at least two magnetic poles. The array of electron beams is generated using an array of columns formed using bores through a magnetic material positioned in the region. Other embodiments, aspects and features are also disclosed.