Semiconductor Lateral Recess Measurement Using SE and BSE Imaging
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Solution Overview
Problem
Current methods for measuring lateral recesses in semiconductor specimens are either destructive, costly, or provide indirect and less accurate measurements, as they rely on cross-sectional electron microscopy or optical inspection technologies that cannot see hidden recesses formed between layers in semiconductor wafers during the fabrication process.
Innovation Solution
A computerized system using an electron beam tool to scan semiconductor specimens with a landing energy that penetrates to a predefined depth, acquiring secondary and backscattered electron images to generate gray level waveforms, allowing for direct measurement of lateral recess widths between layers without damaging the specimen, and calibrating measurements with reference data from TEM for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cross-sectional electron microscopy or optical inspection technologies are used to measure lateral recesses, then measurement capability is provided, but the measurements are indirect and less accurate
Solution Approach 1:
The patent replaces optical inspection technologies with electron beam-based measurement. The electron beam tool emits electrons that interact with the specimen to generate images of the lateral recesses, providing direct and accurate measurements without the limitations of optical methods. This substitution of the detection mechanism enables precise measurement of the recess dimensions that were previously inaccessible.
Solution Approach 2:
The patent uses electron beam penetration depth control to access the lateral recess region that is not visible from the surface. By adjusting the electron beam energy and detection parameters, the system images the recess from a different dimensional perspective (cross-sectional view via electron interaction), enabling direct measurement of the recess dimensions without physical sectioning.
2Measurement precision
If cross-sectional electron microscopy is used to measure lateral recesses, then measurement data is obtained, but the process is destructive and costly
Solution Approach 1:
The patent replaces destructive physical sectioning with non-destructive electron beam imaging. The electron beam interacts with the specimen to generate images without removing material or requiring complex sample preparation. This eliminates the need for costly and time-consuming cross-sectional preparation while maintaining measurement accuracy.
Solution Approach 2:
The patent creates an electronic copy (image) of the lateral recess structure through electron beam interaction. Instead of physically sectioning the specimen to view the recess, the system generates a digital representation that can be measured and analyzed. This copying approach preserves the original specimen while providing accurate measurement data.
3Difficulty of detecting and measuring
If conventional examination tools are used, then surface inspection is possible, but hidden recesses between layers cannot be detected
Solution Approach 1:
The patent replaces surface-only optical inspection with electron beam-based detection that penetrates into the specimen. The electron beam interacts with atoms in the recess region, generating signals that reveal the hidden structure. This substitution enables detection of subsurface features that are completely invisible to conventional optical methods.
Solution Approach 2:
The patent uses electron beam energy and detection angle control to image structures at different depths. By adjusting the measurement parameters, the system accesses information from the hidden recess region between layers, providing a cross-sectional view that reveals dimensions and geometry of features not visible from the surface.
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
Enables non-destructive, accurate, and efficient measurement of lateral recesses, enhancing the precision and control of semiconductor fabrication processes by providing direct and precise geometrical parameters critical for device performance.
Implementation Method 1
scan the semiconductor specimen using an electron beam with a landing energy specifically selected to penetrate to a predefined depth corresponding to a target second layer of the specimen
Implementation Method 2
acquire a first image by collecting secondary electrons (SE) emitted from the surface of the specimen
Implementation Method 3
acquire a second image by collecting backscattered electrons (BSE) scattered from an interior region of the specimen between the surface and the target second layer
Data Source
AI summary
There is provided a system and method of measuring a lateral recess in a semiconductor specimen, comprising: obtaining a first image acquired by collecting SEs emitted from the surface of the specimen, and a second image acquired by collecting BSEs scattered from an interior region of the specimen between the surface and a target second layer, the specimen scanned using an electron beam with a landing energy selected to penetrate to a depth corresponding to the target second layer; generating a first GL waveform based on the first image, and a second GL waveform based on the second image; estimating a first width of the first layers based on the first GL waveform, and a second width with respect to at least the target second layer based on the second GL; and measuring a lateral recess based on the first width and the second width.