Multi-Beam Charged-Particle Optics for Signal Electron Collection
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Solution Overview
Problem
Existing multi-beam charged particle inspection systems face challenges in efficiently collecting signal electrons, particularly when multiple beams are used closely spaced on a sample, which hampers the detection and identification of micro and nano-scale defects in semiconductor manufacturing.
Innovation Solution
A charged-particle optical device is designed with an objective lens array, scintillators, and a light guiding arrangement to project multiple beams onto a sample, where scintillators generate light from signal particles and a light sensor detects this light, aided by a Wien filter array to deflect signal particles towards detectors, improving electron collection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple charged particle beams are used in parallel to increase inspection throughput, then productivity is improved, but the complexity of collecting signal electrons deteriorates
Solution Approach 1:
The detection system is segmented into multiple scintillators, each associated with specific beams, allowing distributed signal collection across multiple independent detection channels rather than attempting to collect all signals through a single complex system
Solution Approach 2:
Scintillators are introduced as intermediary conversion elements that transform charged signal particles into photons, which can then be guided through optical fibers to photodetectors, creating a two-stage conversion process that simplifies the overall collection task
2Productivity
If beams are closely spaced at the sample to increase inspection efficiency, then productivity is improved, but the difficulty of collecting signal electrons from each beam deteriorates
Solution Approach 1:
The system transitions from direct spatial collection in the charged particle domain to optical signal transmission in the photon domain, using the third dimension of optical path routing to separate and guide signals from closely spaced beams to their respective detectors
Solution Approach 2:
The mechanical/electrical collection system for charged particles is replaced with an optical system using scintillators and optical fibers, substituting the challenging task of physically separating closely spaced charged particle signals with the more manageable task of guiding photons through optical pathways
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 configuration enhances the collection of signal electrons, enabling more effective detection and identification of defects, thereby improving the throughput and accuracy in semiconductor inspection processes.
Implementation Method 1
a plurality of scintillators configured to receive signal particles emitted from the sample and to generate light in response to the received signal particles
Implementation Method 2
the light guiding arrangement comprising a mirror defining a plurality of apertures to allow/for passage of the plurality of beams through the mirror towards the sample
Data Source
AI summary
Charged-particle optical devices are disclosed. In one arrangement, a device includes a charged particle column and a light sensor. An objective lens array projects a plurality of beams towards a sample and has a plurality of electrodes arranged along a path of the plurality of beams. A plurality of scintillators receives signal particles emitted from the sample. Light is generated in response to the received signal particles. A light guiding arrangement guides light generated by the scintillators to the light sensor. The light guiding arrangement includes a mirror defining a plurality of apertures to allow passage of the plurality of beams through the mirror towards the sample.