Multilayer Pattern Defect Detection Using Backscattered-Electron Brightness
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Solution Overview
Problem
Conventional methods face challenges in accurately inspecting defects in multilayered semiconductor structures due to varying material, thickness, and depth of interconnect layers, making it difficult to compare pattern edges with design data effectively.
Innovation Solution
A method involving generating a backscattered-electron image of a multilayered structure, classifying regions based on CAD patterns, and calculating brightness index values to detect defects by comparing these values with standard ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a highly-accelerated electron beam is used to generate a transparent image for inspecting interconnect layers, then the ability to visualize multiple layers is improved, but the image contrast becomes unpredictable and dependent on material properties, making conventional Die-to-Database pattern edge comparison ineffective
Solution Approach 1:
The patent changes the detection parameter from pattern edge geometry to brightness intensity. By measuring the brightness index value of backscattered electrons, which reflects the total amount of metal material in each region, the method achieves accurate defect detection without relying on predictable image contrast or pattern edge visualization.
Solution Approach 2:
The patent introduces a brightness index value as an intermediary parameter between the backscattered electron signal and defect detection. This intermediary quantifies the brightness information in a standardized way that can be compared against standard ranges, enabling objective defect identification despite variations in material properties and layer configurations.
2Ease of operation
If conventional Die-to-Database technique is used for pattern inspection, then pattern edge comparison is straightforward, but it cannot effectively detect defects in multilayered structures with varying materials and depths
Solution Approach 1:
The patent creates a universal inspection method that works across all interconnect layers regardless of material composition, layer depth, or thickness variations. The brightness index value approach provides a single metric that can evaluate defects in copper, cobalt, tungsten, or other interconnect materials uniformly, making the technique universally applicable to advanced multilayered semiconductor structures.
Solution Approach 2:
The patent transitions from geometry-based pattern comparison to intensity-based brightness measurement. This parameter change enables the inspection method to adapt to multilayered structures by measuring the cumulative brightness signal from backscattered electrons, which integrates information from all layers rather than requiring separate edge detection for each layer.
3Productivity
If backscattered-electron signals are used to image interconnect layers, then information from multiple layers is obtained simultaneously, but the image contrast varies depending on material, thickness, and overlapping structures
Solution Approach 1:
The patent introduces a brightness index value as an intermediary that quantifies the backscattered electron signal intensity in a standardized manner. This intermediary parameter converts the variable contrast information into a reliable metric that can be consistently compared against standard ranges, enabling reliable defect detection despite variations in material properties and layer configurations.
Solution Approach 2:
The patent establishes a feedback mechanism by comparing the measured brightness index value against a predetermined standard range. This feedback loop automatically identifies defects when the brightness deviates from the expected range, providing reliable and consistent defect detection that is independent of image contrast variations caused by different materials, thicknesses, or overlapping structures.
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 detection of open, short, and overlap defects across multiple semiconductor layers, supporting systematic defect inspection and multilayered structure evaluation.
Implementation Method 1
generating a backscattered-electron image of a multilayered structure including a plurality of patterns formed in a plurality of layers by a scanning electron microscope
Data Source
AI summary
This method includes: generating a backscattered-electron image of a multilayered structure (400) including a plurality of patterns formed in a plurality of layers by a scanning electron microscope (50); classifying a plurality of regions of a virtual multilayered structure (300) including a CAD pattern created from design data of the plurality of patterns into a plurality of groups according to CAD pattern arrays in a depth direction of the virtual multilayered structure (300); performing a matching between at least one of the plurality of patterns on the backscattered-electron image and a corresponding CAD pattern; calculating a brightness index value of a region on the backscattered-electron image corresponding to a region belonging to each group; and determining that there is a pattern defect in the region on the backscattered-electron image when the brightness index value is out of a standard range.