Foreign Object Height Measurement Using Orientation Dependence Data
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Solution Overview
Problem
Current methods for measuring foreign object heights on semiconductor wafers in mass production processes are inefficient, requiring multiple SEM image acquisitions and image processing, resulting in low throughput.
Innovation Solution
A method that measures foreign object height by inclining the sample stage and using dependence data to adjust the orientation of the foreign object image, allowing for high-throughput measurement by extracting and analyzing charged particle images, and outputting reliable height measurements with warnings for orientation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stereoscopic SEM image processing is used to measure foreign object height, then measurement accuracy is improved, but throughput decreases
Solution Approach 1:
The patent extracts only the essential information needed for height measurement from the charged particle image, rather than performing complete stereoscopic image processing. By extracting the foreign object image and calculating its area and orientation, the system obtains sufficient data for height determination without the complexity of full stereoscopic processing, thus improving throughput while maintaining measurement capability
Solution Approach 2:
The patent uses dependence data that stores the relationship between foreign object image area and actual height, obtained through preliminary measurements. This pre-established correspondence allows the system to determine height from a single image's area measurement rather than requiring multiple viewpoint images, significantly improving throughput while preserving measurement accuracy
2Productivity
If single charged particle image analysis is used, then throughput is improved, but measurement reliability decreases due to orientation errors
Solution Approach 1:
The patent calculates the orientation of the foreign object from the charged particle image and compares it against acceptable error ranges stored in dependence data. When the orientation exceeds the acceptable range, the system provides feedback by outputting a warning about measurement reliability, allowing operators to review or re-measure suspicious cases, thus maintaining high throughput while ensuring measurement reliability through selective verification
Solution Approach 2:
The patent pre-calculates and stores dependence data including the relationship between image area, orientation, and actual height, as well as acceptable orientation error ranges. This preliminary preparation allows the measurement system to quickly assess reliability without complex real-time calculations, maintaining both high throughput and reliable measurements
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-throughput measurement of foreign object heights on semiconductor wafers, improving process efficiency and reducing yield loss by ensuring accurate and reliable data collection.
Implementation Method 1
a charged particle image acquired by irradiating the sample with a charged particle beam
Data Source
AI summary
A foreign object height measurement method including: storing in advance dependence data indicating a dependence of a calculated value of the height of the foreign object calculated from a foreign object image extracted from the charged particle image on an orientation of the foreign object; extracting a measurement target foreign object image, being an image of a measurement target foreign object, from the charged particle image; and outputting a measurement value of a height of the measurement target foreign object along with a warning regarding reliability or measuring the height of the measurement target foreign object from a charged particle image acquired by rotating the sample stage and changing an orientation of the measurement target foreign object detected from the measurement target foreign object image when it is determined that the orientation of the measurement target foreign object does not satisfy an acceptable error range based on the dependence data.