Wafer Cross-Section Imaging for Deep 3D Inspection Volumes
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Solution Overview
Problem
Current methods for generating 3D volume images of semiconductor wafers are limited by the need to remove samples for inspection, lack precision in depth determination, and struggle with high throughput and resolution, especially for deep and complex structures.
Innovation Solution
A dual beam device and method for 3D inspection of wafer inspection volumes using a wedge-cut geometry, allowing cross-sectioning and imaging without sample removal, with high lateral resolution and depth extension, enabling precise depth determination and high-throughput inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional cross-section imaging methods are used, then sample extraction is required for inspection, but this reduces productivity and increases complexity
Solution Approach 1:
The inspection volume is divided into multiple cross-section image slices at different depths, allowing non-destructive 3D reconstruction of the wafer structure without sample extraction, thereby maintaining productivity while achieving precise depth determination
Solution Approach 2:
The method transitions from conventional 2D surface imaging to 3D volume imaging by acquiring cross-section slices at multiple depths and reconstructing the volumetric structure, enabling precise depth determination without sacrificing throughput
2Measurement precision
If higher resolution imaging is achieved, then measurement precision improves, but inspection time increases reducing throughput
Solution Approach 1:
The 3D volume is segmented into multiple 2D cross-section slices that can be acquired and processed independently, allowing parallel processing and reducing total inspection time while maintaining high lateral resolution in each slice
Solution Approach 2:
Instead of imaging the entire wafer at maximum resolution, the method applies high resolution only to selected regions of interest in each cross-section slice, reducing total inspection time while maintaining precision where needed
3Length of stationary object
If deep structures are inspected, then measurement capability increases, but image quality and resolution deteriorate
Solution Approach 1:
The deep inspection volume is divided into multiple shallow cross-section slices at different depth levels, allowing each slice to be imaged with high resolution while collectively covering the entire deep structure
Solution Approach 2:
The method uses angular diversity in cross-section imaging to achieve depth resolution, complementing the spatial resolution in the lateral direction, thereby maintaining image quality throughout the full depth extension
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 high-resolution, high-precision 3D volume imaging of semiconductor wafers without sample extraction, facilitating accurate defect detection and process monitoring with improved throughput.
Implementation Method 1
milling a first cross section surface at a slanted angle GF in the first inspection volume with the FIB column
Implementation Method 2
imaging the first cross section surface with a charged particle imaging device to form a first cross section image slice
Data Source
AI summary
The present disclosure relates to dual beam device and three-dimensional circuit pattern inspection techniques by cross sectioning of inspection volumes with large depth extension exceeding 1 μm below the surface of a semiconductor wafer, as well as methods, computer program products and apparatuses for generating 3D volume image data of a deep inspection volume inside a wafer without removal of a sample from the wafer. The disclosure further relates to 3D volume image generation and cross section image alignment methods utilizing a dual beam device for three-dimensional circuit pattern inspection.