Dual Wien Filter Aberration Correction for Multi-Beam SEM
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Solution Overview
Problem
Chromatic aberration in electron beam imaging systems, particularly induced by Wien filters, hinders the resolution performance and image uniformity in semiconductor manufacturing metrology and inspection systems.
Innovation Solution
A dual-Wien filter configuration is employed, with strategically positioned Wien filters and a correction lens to correct chromatic aberrations by balancing the strengths and polarities of the Wien filters, ensuring that the secondary electrons are deflected correctly to a detector, thereby improving image resolution and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Wien filters are used to deflect electron beams, then beam deflection and secondary electron detection are achieved, but chromatic aberration is introduced that degrades image resolution
Solution Approach 1:
The patent employs a dual-Wien filter configuration where the second Wien filter is positioned and configured to counteract the chromatic aberration introduced by the first Wien filter. By strategically positioning these filters and adjusting their strengths and polarities, the system creates opposing effects that cancel out the harmful chromatic aberration while preserving the necessary beam deflection function
Solution Approach 2:
A correction lens is introduced as an intermediary element between the Wien filters and the imaging system. This correction lens serves as a mediator that compensates for the chromatic aberration effects, allowing the Wien filters to perform their beam deflection function while the correction lens restores the image quality by counteracting the introduced aberrations
2Measurement precision
If multiple Wien filters are added to correct chromatic aberration, then image resolution is improved, but device complexity increases
Solution Approach 1:
The dual-Wien filter system is designed so that the second Wien filter serves multiple functions: it corrects the chromatic aberration from the first filter while simultaneously maintaining the necessary beam deflection capability. This multi-functionality approach allows the system to achieve aberration correction without proportionally increasing device complexity, as the correction mechanism is integrated into the existing beam deflection architecture
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 dual-Wien filter system effectively corrects chromatic aberrations, enhancing the resolution and uniformity of electron beam imaging systems, thereby improving the efficiency and accuracy of semiconductor device inspection and metrology.
Implementation Method 1
Wien filter-induced chromatic aberration
Implementation Method 2
image-forming lens systems
Data Source
AI summary
Two Wien filters are disposed in the path of the charged particle beam between a source and an objective lens, which is downstream of the two Wien filters. The optics also includes a gun lens and a correction lens. The second Wien filter can deflect the secondary electrons to a detector. The charged particle beam may be an electron beam. The charged particle beam may include beamlets.