Optical Inspection Recipe Selection for 3D NAND Buried Defects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing inspection tools are inefficient in detecting buried defects in 3D NAND technologies due to their design focusing on single planar layers, which is inadequate for vertically stacked layers in semiconductor wafers.
Innovation Solution
A method and system that utilize a set of optical modes and algorithms to scan full-stack wafers, de-process them to identify defect locations, and form a recipe for defect inspection, allowing for the selection of suitable optical modes and algorithms for effective defect detection in wafers with vertically stacked layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If inspection tools are designed for single planar layers, then the device complexity is reduced and ease of manufacture is improved, but the measurement precision and reliability for detecting buried defects in 3D NAND vertically stacked layers deteriorates
Solution Approach 1:
The inspection process is segmented into multiple passes with different optical modes. The first pass uses through-focus stack imaging to identify potential defect locations, while the second pass uses targeted optical modes to verify defects at those locations. This segmentation allows the system to handle complex 3D NAND structures without requiring a complete redesign of the inspection tool, thus maintaining ease of manufacture while improving measurement precision.
Solution Approach 2:
The patent transitions from traditional single-layer 2D inspection to multi-layer 3D inspection by introducing through-focus stack imaging that captures images at multiple focal depths. This dimensional change enables the detection of buried defects in vertically stacked layers while using existing optical inspection tools, avoiding the need for completely new complex instrumentation.
2Device complexity
If traditional optical inspection methods are used for full-stack wafers, then the device complexity remains low, but the productivity and inspection efficiency deteriorates due to inability to detect buried defects
Solution Approach 1:
The system performs preliminary through-focus stack imaging to identify potential defect locations before conducting detailed verification. This preliminary action filters out false positives and focuses subsequent detailed inspection only on areas with actual defects, significantly improving productivity without requiring complex additional hardware.
Solution Approach 2:
Instead of inspecting the entire full-stack wafer with high-resolution targeted modes (which would be time-consuming), the system uses partial action by first scanning with through-focus stack imaging and then applying targeted optical modes only to regions containing potential defects. This approach maintains low device complexity while dramatically improving inspection efficiency.
3Measurement precision
If multiple optical modes are used to scan full-stack wafers to identify buried defects, then the measurement precision improves, but the loss of time and number of wafers needed for inspection increases
Solution Approach 1:
Through-focus stack imaging serves as a preliminary screening step that quickly identifies potential defect locations without requiring time-consuming detailed inspection of the entire wafer surface. This preliminary action reduces the number of wafers and time needed for subsequent detailed verification by focusing only on areas with actual defects.
Solution Approach 2:
The system applies multiple optical modes partially rather than exhaustively - using through-focus stack imaging for initial screening and then applying targeted optical modes only to specific regions containing potential defects. This partial application of multiple modes maintains measurement precision while significantly reducing inspection time compared to exhaustive multi-mode scanning of entire wafers.
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 efficient detection of buried defects in wafers by identifying the appropriate optical modes and algorithms, reducing the time and number of wafers needed for inspection, and allowing for the creation of a reusable inspection recipe for similar types of wafers.
Implementation Method 1
scanning a full-stack wafer of the particular type utilizing a set of optical modes to obtain a set of full-stack wafer images
Data Source
AI summary
Methods and systems for selecting optical modes suitable for defect inspection are disclosed. A method may include: scanning a full-stack wafer of the particular type utilizing a set of optical modes to obtain a set of full-stack wafer images; and de-processing the full-stack wafer to produce a de-processed wafer based on a location of a potential defect of interest indicated by the set of full-stack wafer images to facilitate selection of optical modes suitable for defect inspection of wafers of the particular type.