Charged Particle Multi-Beam Inspection for Wafer Throughput
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Solution Overview
Problem
Conventional single-beam Scanning Electron Microscopes (SEM) are inefficient for inspecting semiconductor wafers due to slow scanning times, limiting throughput and resolution, especially as defect sizes shrink beyond the 20 nm node, necessitating high-resolution and fast inspection tools that existing light optical tools cannot provide.
Innovation Solution
A charged particle multi-beam device and method utilizing an array of primary charged particle beamlets, generated by a charged particle beam source, a multi-aperture lens plate, field curvature correction electrodes, and a deflector array to focus beamlets on separate locations, enabling simultaneous inspection with improved resolution and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single finely focused electron beam is used to scan the wafer surface, then high resolution inspection is achieved, but the inspection time becomes too long to meet production throughput requirements
Solution Approach 1:
The patent divides a single electron beam into multiple parallel beamlets using a multi-aperture lens plate. Each beamlet independently scans a separate location on the wafer, enabling simultaneous inspection of multiple areas. This segmentation of the beam path directly increases throughput while maintaining the high resolution capability of focused electron beams.
2Reliability
If the entire wafer surface is scanned to detect all defects, then complete inspection coverage is achieved, but the inspection process becomes too slow for practical production use
Solution Approach 1:
Multiple beamlets are generated to scan different regions of the wafer simultaneously, allowing complete coverage to be achieved in parallel rather than sequentially. This reduces total inspection time while maintaining comprehensive defect detection across the entire wafer surface.
Solution Approach 2:
The patent adds a spatial dimension to the inspection process by arranging beamlets in parallel arrays that cover different areas of the wafer at once. This dimensional expansion from single-point scanning to multi-point simultaneous scanning enables complete coverage without proportionally increasing inspection time.
3Productivity
If light optical tools are used for inspection, then fast inspection speed is achieved, but the resolution is insufficient to detect defects at the 20 nm node and beyond
Solution Approach 1:
The patent replaces light optical inspection systems with electron beam-based inspection. Electrons have much shorter wavelengths than visible light, enabling resolution at the 20 nm node and beyond while maintaining high inspection speeds through parallel multi-beamlet operation.
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 allows for rapid and high-resolution inspection of semiconductor wafers by generating an array of focused beamlets that can inspect multiple locations simultaneously, overcoming the limitations of single-beam SEMs and providing the necessary throughput for modern semiconductor manufacturing.
Implementation Method 1
generating a primary charged particle beam with a charged particle beam emitter; illuminating a multi-aperture lens plate with the primary charged particle beam to generate the array of primary charged particle beamlets which are focused
Implementation Method 2
correcting a field curvature of the charged particle beam device with at least two electrodes, wherein the at least two electrodes comprise aperture openings
Implementation Method 3
guiding the primary charged particle beamlets through a deflector array arranged within the lens; wherein the combined action of the lens and the deflector array directs the primary charged particle beamlets through a coma free point of the objective lens
Implementation Method 4
focusing the primary charged particle beamlets on separate locations on the specimen with the objective lens to simultaneously inspect the specimen at the separate locations
Data Source
AI summary
A method of inspecting a specimen with an array of primary charged particle beamlets in a charged particle beam device is described. The method includes generating a primary charged particle beam with a charged particle beam emitter; illuminating a multi-aperture lens plate with the primary charged particle beam to generate the array of primary charged particle beamlets; correcting a field curvature with at least two electrodes, wherein the at least two electrodes include aperture openings; directing the primary charged particle beamlets with a lens towards an objective lens; guiding the primary charged particle beamlets through a deflector array arranged within the lens; wherein the combined action of the lens and the deflector array directs the primary charged particle beamlets through a coma free point of the objective lens; and focusing the primary charged particle beamlets on separate locations on the specimen with the objective lens.