Charged Particle Beam System with Offset Imaging
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Solution Overview
Problem
Charged particle beam processing systems face limitations in achieving high spatial resolution due to physical interference between imaging and processing subsystems, which affects the precision of substrate processing, especially when dealing with buried structures in semiconductor devices.
Innovation Solution
The system physically separates the imaging and processing subsystems and uses a precision stage to transport the substrate between them, allowing for accurate determination and correction of positional errors through near-infrared and visible light imaging, enabling precise alignment of the charged particle beam for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If imaging and processing subsystems are integrated within a small volume, then both imaging and processing can be performed without substrate motion, but the subsystems physically interfere with each other, limiting spatial resolution
Solution Approach 1:
The system divides the imaging and processing functions into separate physical subsystems with independent optical axes. The imaging subsystem and charged particle column are spatially separated, each optimized for their respective functions without physical interference, thereby maintaining high spatial resolution while enabling sequential operation through substrate transport.
2Manufacturing precision
If imaging and processing subsystems are physically separated, then spatial resolution is improved, but substrate must be moved between subsystems, introducing positional errors
Solution Approach 1:
The system employs a feedback mechanism where the imaging subsystem captures images of fiducial markers on the substrate before processing. The system then calculates positional offsets between the imaged marker positions and the intended processing locations, and applies corrective transformations to the charged particle beam coordinates, thereby compensating for substrate positioning errors and maintaining high processing accuracy.
Solution Approach 2:
The system replaces reliance on purely mechanical positioning accuracy with an optical-mechanical hybrid approach. Instead of depending solely on the precision of the substrate transport mechanism, the system uses optical imaging to detect actual positions and computationally corrects for deviations, substituting mechanical precision requirements with optical measurement and computational compensation.
3Measurement precision
If charged particle beam is used for imaging, then spatial resolution is high, but the beam may induce damage such as milling or contamination
Solution Approach 1:
The system introduces optical imaging as an intermediary for navigation and endpoint detection. Instead of using the charged particle beam directly for imaging, the system employs separate optical imaging subsystems that can detect substrate features and processing progress without causing damage, reserving the charged particle beam exclusively for non-damaging processing operations.
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 enhances the spatial resolution and accuracy of both imaging and processing by minimizing interference and positional errors, allowing for effective processing of buried structures without damaging the substrate.
Implementation Method 1
Near-infrared (NIR) imaging has an advantage of being able to penetrate through these layers
Implementation Method 2
Visible light has some ability to penetrate these layers, as well
Implementation Method 3
Some embodiments of the present invention provide a method for very accurately determining the (open-loop) positioning error, and then for correcting this error (closing the loop) by modifying the substrate position or by deflecting the processing beam
Implementation Method 4
the circuit layers can be imaged using visible light to locate the exact device positions for charged particle beam processing, such as cutting and adding interconnects
Data Source
AI summary
A charged particle beam system for processing substrates is disclosed, comprising a charged particle column, combination infrared radiation and visible light illumination and imaging subsystems, in-vacuum optics, and a precision stage for supporting and positioning the substrate alternately under the charged particle column and the imaging system. The axes of the charged particle column and imaging system are offset to enable much closer working distances for both imaging and beam processing than would be possible in a single integrated assembly. A method for extremely accurately calibrating the offset between the column and imaging system is disclosed, enabling beam processing at precisely-determined locations on the substrate. The imaging system is capable of locating sub-surface features on the substrate which cannot be seen using the charged particle beam. Two illumination modes are disclosed, enabling both bright-field and dark-field imaging in infrared radiation and visible light.