Pattern Measurement Device Using Focused Ion Beam Inclined Surface
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Solution Overview
Problem
Current methods for measuring the dimensions of miniaturized semiconductor patterns with three-dimensional structures face challenges in accuracy due to the difficulty in accurately calculating depth and shape measurements without cutting the wafer, leading to yield deterioration and inefficiencies in mass production processes.
Innovation Solution
A pattern measurement method and device using a scanning electron microscope to form an inclined surface with a focused ion beam, allowing for high-accuracy measurement of dimensions in the depth direction by specifying positions and calculating dimensions based on the angle of the inclined surface, without cutting the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wafer is cut to observe the section of the pattern, then the sectional shape can be observed, but the wafer is lost and yield is deteriorated
Solution Approach 1:
The patent creates a virtual copy of the sectional view by using image processing techniques. A projection image is generated from a top-down SEM image, and a simulated sectional image is created by processing this projection image to show the depth information and cross-sectional structure without physically cutting the wafer. This virtual copying approach allows observation of sectional shapes while preserving the original wafer.
Solution Approach 2:
The patent replaces the mechanical cutting process with an optical and computational approach. Instead of using a physical saw or knife to cut the wafer, the system uses a scanning electron microscope to capture images and then applies image processing algorithms to generate virtual sectional views. This substitution eliminates the need for physical destruction of the sample.
2Difficulty of detecting and measuring
If the wafer is cut and the section of the pattern is observed, then the sectional shape can be detected, but several hours have elapsed and yield is deteriorated
Solution Approach 1:
The patent replaces the time-consuming mechanical cutting and mounting process with rapid optical imaging and computational processing. The scanning electron microscope can capture the entire wafer surface quickly, and the image processing algorithms automatically generate sectional views in minutes rather than hours, dramatically reducing the measurement time while maintaining detection capability.
Solution Approach 2:
The patent performs preliminary image capture of the entire wafer surface before any analysis is needed. By acquiring the top-down SEM image first and then processing it to generate projection images and virtual sectional views on demand, the system prepares the data in advance, allowing rapid retrieval and analysis without repeating the time-consuming cutting process.
3Measurement precision
If a hole is drilled in the direction perpendicular to the sample surface, then the section of the pattern can be observed, but the drilled volume is large and the required time is long
Solution Approach 1:
The patent creates a virtual copy of the cross-sectional view by processing the top-down image data. Instead of physically drilling holes to expose cross-sections, the system uses image processing to simulate what the cross-section would look like, extracting depth information and structural details from the projection image. This virtual copying provides accurate depth measurements without the time-consuming drilling process.
Solution Approach 2:
The patent extracts the essential depth and cross-sectional information from the three-dimensional structure by processing the top-down image. Through image processing techniques, the system extracts depth profiles, cross-sectional shapes, and dimensional data without needing to physically access those sections through drilling or cutting, thereby maintaining productivity while achieving measurement precision.
4Loss of information
If the dimension in the height direction is calculated based on scanning distance and inclination angle, then depth information can be acquired, but high-accuracy measurement is difficult due to uncertainty in start point and end point
Solution Approach 1:
The patent creates a virtual projection image that serves as an accurate reference copy of the pattern's footprint. By processing this projection image to generate a virtual sectional view, the system can precisely identify the start and end points of features in the depth direction. The virtual images provide clear visual references that eliminate the ambiguity present in direct depth measurements, enabling high-accuracy measurement of height and depth dimensions.
Solution Approach 2:
The patent introduces virtual projection images and virtual sectional images as intermediary representations between the physical sample and the measurement process. These virtual images serve as mediators that translate three-dimensional structural information into two-dimensional representations with clear depth cues. By measuring dimensions on these virtual images rather than directly on the physical sample, the system achieves higher measurement precision while preserving depth information.
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-accuracy measurement of pattern dimensions in the depth direction, improving process stability and reducing yield loss by allowing for non-destructive evaluation of semiconductor patterns, thus enhancing the efficiency of mass production processes.
Implementation Method 1
a step of forming an inclined surface in a sample area including the circuit element by irradiating the sample area with a focused ion beam
Implementation Method 2
acquiring an image of the field of view based on a detection signal acquired by scanning the field of view with an electron beam
Data Source
AI summary
The presently disclosed subject matter provides a pattern measurement method and device for achieving highly accurate measurement in the depth direction of a pattern. The method involves a focused ion beam irradiated to form an inclined surface in a sample area; a field of view of a SEM set to include the boundary between the inclined surface and a sample surface; and an image of the field of view obtained on the basis of a detection signal. Such an acquired image is used to specify a first position, the boundary between inclined surface and non-inclined surface, and a second position, the position of a desired deep hole or deep groove positioned within the inclined surface. The pattern dimension in a height direction is determined on the basis of the distance in the sample surface direction between the first position and second position and the angle of the inclined surface.