Specimen Preparation for Scanning Capacitance Microscopy
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Solution Overview
Problem
The manual grinding method for preparing semiconductor specimens for scanning capacitance microscopy lacks precision, especially when dealing with small structural sizes, leading to errors in cross-sectional sample preparation and inaccurate analysis results due to limitations in optical microscopy resolution and human judgment.
Innovation Solution
A method combining manual grinding with plasma focused ion beam technology, where a plasma focused ion beam corrects the error angle caused by manual grinding, allowing for precise control of the cross-sectional position and preparation of specimens for scanning capacitance microscopy analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If manual grinding is used to prepare cross-sectional samples, then the preparation process is simple and equipment requirement is low, but the grinding accuracy and positioning precision deteriorate when structural sizes are reduced to close to or exceed the resolution of optical microscopy
Solution Approach 1:
The preparation process is divided into two distinct stages: manual grinding to create an initial flat surface, followed by FIB cutting to achieve precise cross-sectional positioning. This segmentation allows each method to operate within its optimal capability range, with manual grinding handling rough preparation and FIB handling precision work.
Solution Approach 2:
The manually ground flat surface serves as an intermediary between the simple manual grinding process and the precise FIB cutting process. This intermediate surface provides a stable foundation that enables accurate FIB positioning and cutting, bridging the gap between low-precision and high-precision methods.
2Device complexity
If manual grinding is used with optical microscopy for position confirmation, then the equipment complexity is low, but the measurement precision and detection accuracy deteriorate due to optical microscopy resolution limitations
Solution Approach 1:
The patent replaces the optical microscopy-based visual positioning system with a FIB-based physical cutting and positioning system. The FIB system uses electron beam guidance and automated control to achieve positioning precision far beyond optical microscopy capabilities, substituting a mechanical/optical system with a more advanced beam-based system.
Solution Approach 2:
The patent changes the detection parameter from optical wavelength-scale resolution to electron beam-scale resolution. By using FIB cutting with scanning electron microscopy guidance, the positioning precision transitions from micrometer/optical resolution to nanometer/electron resolution, dramatically improving measurement accuracy.
3Ease of operation
If manual grinding is performed to achieve a level surface, then the operation is straightforward, but the error angle relative to horizontal line cannot be avoided, leading to uneven grinding sections
Solution Approach 1:
The manual grinding step performs a preliminary action of creating a flat reference surface, but the critical precision action of achieving exact horizontal levelness and precise cross-sectional positioning is left for the FIB cutting step. This preliminary action prepares the sample for the subsequent high-precision operation without attempting to achieve final precision itself.
Solution Approach 2:
The patent extracts the precision-critical function of achieving exact horizontal levelness and positioning from the manual grinding process and assigns it to the FIB cutting process. This separation allows manual grinding to focus on simplicity and rough flatness, while FIB cutting handles the extraction of precision requirements.
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 enhances the accuracy and quality of specimen preparation, enabling precise analysis of small semiconductor structures that were previously inaccessible, by eliminating the error angle and ensuring accurate horizontal positioning.
Implementation Method 1
cutting the grinding stopping surface by a plasma focused ion beam equipped with a scanning electron microscopy toward the target region and stopping at a distance of d2 from the longitudinal section
Data Source
AI summary
The present invention discloses a method of preparing a specimen for scanning capacitance microscopy, comprising the steps of: providing a sample including at least one object to be analyzed; manually grinding the sample from an edge of the sample toward a target region containing the object to be analyzed gradually, and stopping at a distance of dl from a longitudinal section of the at least one object to be analyzed in the target region to form a grinding stopping surface; cutting the grinding stopping surface by a plasma focused ion beam equipped with a scanning electron microscopy toward the target region and stopping at a distance of d2 from the longitudinal section to form a cutting stopping surface, wherein 0<d2<d1; and manually grinding to polish the cutting stopping surface and gradually remove the part of the sample between the longitudinal section and the cutting stopping surface to expose the longitudinal section of the at least one object to be analyzed, and complete the preparation of a specimen for scanning capacitance microscopy.