Infrared Microscope Positioning for Charged Particle Beam Subsurface Processing
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Solution Overview
Problem
Conventional charged particle beam apparatuses face challenges in determining the processing position, especially when the processing area is below the sample surface and obscured by opaque or transparent insulating films, as they rely on visible light optical microscopes and laser marking, which fail to work effectively in such cases.
Innovation Solution
The use of an infrared microscope for observation and laser marking around the processing area, combined with CAD data registration and correlation with secondary charged particle images, allows for accurate positioning regardless of the sample surface characteristics, including opaque films, by forming a deposition film for laser absorption when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visible light optical microscope is used for processing positioning, then the sample surface can be observed, but the processing area below the sample surface cannot be observed when obscured by opaque or transparent insulating films
Solution Approach 1:
The patent introduces an infrared microscope as an intermediary observation tool that can penetrate insulating films to visualize the processing area below the surface. The infrared microscope serves as a mediator between the charged particle beam system and the obscured processing region, enabling positioning without direct line-of-sight visibility.
Solution Approach 2:
The patent replaces the visible light optical microscope system with an infrared microscope system. This substitution changes the wavelength regime from visible light to infrared, allowing penetration through insulating films that are opaque or transparent to visible light, thereby resolving the visibility problem for sub-surface processing areas.
2Ease of manufacture
If laser marking is performed for positioning, then the processing area can be marked, but no laser marking can be performed when there is no absorption of laser beam in the insulating film
Solution Approach 1:
The patent changes the wavelength parameter of the laser from visible/near-infrared to far-infrared range where insulating films exhibit absorption characteristics. This parameter change enables laser marking on insulating films that are transparent to conventional laser wavelengths, expanding the method's applicability to various sample types.
Solution Approach 2:
The patent performs preliminary observation using infrared microscope to identify the processing area and plan the laser marking positions before actually performing the laser marking. This preliminary action ensures that laser marking can be effectively applied even on samples with varying absorption characteristics.
3Measurement precision
If superposition of optical image and secondary charged particle image is used for positioning, then the processing position can be determined, but the superposition cannot be performed when no characteristic shape exists on the sample surface
Solution Approach 1:
The infrared microscope image serves as an intermediary reference that provides characteristic shapes and features of the processing area even when the sample surface lacks distinctive features. This intermediary information enables accurate superposition and alignment with the secondary charged particle image for positioning.
4Measurement precision
If conventional processing positioning methods are used, then the sample surface can be observed, but accurate positioning below the sample surface cannot be achieved
Solution Approach 1:
The patent integrates the infrared microscope functionality into the existing charged particle beam apparatus, making the system multi-functional. The infrared microscope can observe both surface and sub-surface features, serving multiple purposes: visualization of obscured areas, alignment reference provision, and processing position determination, thereby achieving accurate positioning without significantly increasing overall system complexity.
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 method enables accurate and easy processing positioning in charged particle beam apparatuses, allowing observation of wiring layers through opaque substrates and insulating films, and facilitates precise alignment by correlating infrared and secondary charged particle images with CAD data.
Implementation Method 1
By using the infrared microscope for the optical observation system, in addition to a transparent sample, it is possible to observe a wiring layer while transmitting through for instance an Si substrate used in a device.
Implementation Method 2
in a case where no absorption of the laser beam is performed by a sample, performing the laser marking on a deposition film formed on the sample surface by a charged particle beam
Implementation Method 3
performing the laser marking on the periphery of the processing/observation area
Implementation Method 4
forming ahead of time a deposition film on the sample surface by the charged particle beam
Implementation Method 5
correlating the secondary charged particle image and the registered data
Data Source
AI summary
A laser mark which will be the positioning mark for a secondary charged particle image in the charged particle beam apparatus is applied by moving the sample processing/observation area in the charged particle beam apparatus so as to come into the view field while performing an observation by an infrared microscope, and by a using a laser optical system disposed coaxially with an optical observation system, the mark made at the periphery of the processing/observation object area. Next, by a superposition of an infrared transmission image and a CAD data, the processing/observation object area and the laser mark are registered onto the CAD data. And, by a correlation of the registered data read from the charged particle beam apparatus and the secondary charged particle image, it is possible to accurately and easily determine the processing position.