SEM Detector Assembly for Concurrent BSE Imaging and X-Ray Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing scanning electron microscopy (SEM) systems struggle with synchronous performance of backscattered electron (BSE) imaging and x-ray analysis due to low signal acquisition, leading to inefficient defect detection and elemental composition identification in high-aspect-ratio structures of 3D semiconductor devices.
Innovation Solution
A system and method utilizing silicon-drift detectors (SDD) integrated into the charge control plate region of the SEM column to concurrently collect BSE and x-ray signals, enhancing signal-to-noise ratio and x-ray collection efficiency, enabling real-time elemental analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional silicon lithium detector diodes are used to operate at liquid nitrogen temperature, then electron-hole pair is reduced and noise in the FET preamplifier is reduced, but the detector must be isolated from the electron beam column causing low signal collection of x-ray signals
Solution Approach 1:
The patent changes the operating temperature parameter from liquid nitrogen temperature to liquid helium temperature (4K), which enables the use of superconducting materials in the SDD. This parameter change allows the detector to achieve both low noise operation and high x-ray signal collection efficiency simultaneously, resolving the contradiction between measurement precision and signal quantity.
Solution Approach 2:
The patent employs composite material structure by combining superconducting materials with the silicon drift detector architecture. The superconducting materials are integrated into the SDD to enhance x-ray detection efficiency while maintaining low noise performance, thus resolving the contradiction between signal-to-noise ratio and x-ray signal collection.
2Measurement precision
If BSE imaging and x-ray analysis are performed separately in existing systems, then each function can be optimized, but repeated adjustments and searches are required increasing inspection time
Solution Approach 1:
The patent merges BSE imaging and x-ray analysis functions into a single integrated detection system using SDD. This merging allows both functions to be performed simultaneously without requiring separate adjustments and searches, thus reducing inspection time while maintaining defect detection accuracy.
Solution Approach 2:
The SDD detector assembly is designed to perform multiple functions simultaneously - both BSE imaging and x-ray analysis. This multi-functionality eliminates the need for separate optimization and adjustment processes, reducing inspection time while maintaining high measurement precision for both functions.
3Reliability
If the silicon lithium detector is isolated from the electron beam column to prevent contamination, then the cooling silicon crystal surface is protected from build up, but x-ray signal collection efficiency is reduced
Solution Approach 1:
The patent changes the operating temperature to liquid helium temperature (4K), which enables superconducting materials to be used in the detector. This parameter change allows the detector to achieve both contamination resistance and high x-ray signal collection efficiency, resolving the contradiction between reliability and signal quantity.
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 simultaneous BSE and x-ray signal collection, allowing for real-time elemental analysis and improved defect detection in high-aspect-ratio structures with enhanced signal-to-noise ratio and reduced acquisition time.
Implementation Method 1
one or more silicon-drift detector (SDD) sensors configured to concurrently collect one or more backscattered electron (BSE) signals and one or more x-ray signals
Implementation Method 2
an electron beam source configured to generate a primary electron beam
Data Source
AI summary
A system may include an electron beam source configured to generate a primary electron beam and an electron-optical column including a set of electron-optical elements configured to direct at least a portion of the primary electron beam onto a portion of a sample. The set of electron-optical elements may include an objective lens disposed along an optical axis, where the objective lens includes one or more charge control plates (CCPs), where the electron-optical column includes a detector assembly configured to concurrently collect one or more backscattered electron (BSE) signals and one or more x-ray signals emanated from the sample. The detector assembly may include one or more silicon-drift detector (SDD) sensors and one or more BSE sensors.