Silicon Standard Member for Electron Microscope Calibration
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Solution Overview
Problem
Existing calibration samples for scanning electronic microscopes face issues such as level differences leading to astigmatic errors, damage from adhesive agents, and precision errors due to inclination and interference in diffraction measurements, which hinder high-precision magnification calibration for miniaturized semiconductor devices.
Innovation Solution
A standard member is created by bonding two substrates with multi-layer film structures, aligning their plane directions, and forming concavity and convexity patterns on cross-section surfaces, allowing for precise magnification calibration without adhesive-induced damage and minimizing level differences, using techniques like anodic bonding and selective etching to achieve vertical cross-section surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive agents are used to bond substrates together, then the substrates can be fixed in position, but the adhesive agent causes damage to superlattice patterns and creates foreign material contamination
Solution Approach 1:
The invention removes the adhesive agent from the bonding process entirely. Instead of using adhesive to bond substrates, the patent employs direct substrate bonding through precise mechanical alignment and bonding techniques, eliminating the source of pattern damage and foreign material contamination.
Solution Approach 2:
The invention introduces a bonding interface that directly connects substrates without adhesive intermediaries. By using direct substrate-to-substrate bonding with proper alignment fixtures, the patent eliminates the harmful adhesive layer while maintaining strong bonding between substrates.
2Ease of manufacture
If cross-section surfaces are used for calibration, then the sample can be prepared, but level differences occur causing local surface electric field distribution and astigmatic errors
Solution Approach 1:
The invention creates a flat, level bonding surface that eliminates height differences between bonded substrates. By ensuring the bonding interface is coplanar with the substrate surfaces, the patent prevents local electric field variations and astigmatic errors during electron beam scanning.
Solution Approach 2:
The patent transitions from using cross-section surfaces (which create height variations) to using top surfaces for bonding and calibration. By bonding substrates face-to-face and then creating cross-sections from the bonded assembly, the invention ensures the calibration patterns lie on a flat, level surface.
3Shape
If mechanical abrasion is used to prepare cross-section surfaces, then the surfaces can be flattened, but precision setup is limited causing inclination errors and calibration errors
Solution Approach 1:
The invention replaces mechanical abrasion with chemical etching methods to create vertical cross-section surfaces. By using controlled chemical etching on the bonded substrate assembly, the patent achieves precise verticality without the alignment limitations of mechanical abrasion equipment.
4Measurement precision
If diffraction angle measurement is used to measure pitch linewidth, then average pitch can be obtained, but interference occurs between diffracted rays from multiple cross-section samples reducing measurement precision
Solution Approach 1:
The invention segments the measurement process by measuring each substrate's pitch linewidth separately before bonding. This prevents interference between diffracted rays during measurement, as each substrate is measured independently. The pre-measured pitch values are then used for magnification calibration of the bonded assembly.
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 enables accurate and precise magnification calibration, reducing calibration errors to within 0.02 nm and avoiding local surface electric field distributions, thereby enhancing the precision of dimensional control in semiconductor manufacturing.
Implementation Method 1
a first sample cube and a second sample cube, each comprising a multi-layer film structure in which different materials are alternately deposited in layers over the surface of a substrate
Implementation Method 2
the cross-section surfaces are (111) surfaces when the surfaces of both the substrates are (110) surfaces, and the cross-section surfaces are (110) surfaces when the surfaces of both the substrates are (100) surfaces
Data Source
AI summary
This invention provides a standard member allowing magnification calibration for use in an electron microscope to be performed with high precision. A (110) or (100) oriented silicon substrate including a magnification calibration pattern comprised of a constant pitch periodic pattern and a (110) or (100) oriented silicon substrate not including the constant pitch periodic pattern are bonded together by means of bonding without using an adhesive agent, while aligning the plane directions of the surfaces of the two substrates in the same orientation. Then, the thus bonded substrates are cleaved or diced so that their (111) surfaces or (110) surfaces become cross-section surfaces. Further, by selectively etching one side of the constant pitch periodic pattern, a standard member with no level difference and no damage to superlattice patterns and having a constant pitch concavity and convexity periodic pattern in a cross-section surface vertical to the substrate surface is created.