Local Shape Deviation Detection in Semiconductor Specimens

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Solution Overview

Problem

Conventional critical dimension (CD) metrology methods fail to accurately detect local shape deviations in semiconductor specimens, which can affect electrical measurements and device performance, as they rely on geometric parameters that are insufficient for advanced process control in complex feature structures.

Innovation Solution

A computerized system using processing and memory circuitry to estimate a reference contour based on a Fourier descriptor, optimized with a loss function insensitive to local shape deviations, allowing for precise measurement of differences between actual and reference contours to detect local shape deviations in semiconductor specimens.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional CD metrology methods are used to measure geometric dimensions, then basic feature measurements can be obtained, but local shape deviations cannot be accurately detected

Engineering Contradiction:

Improvedetection accuracy of local shape deviationVSAvoidcomplexity of metrology method

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the contour measurement problem into two distinct components: the reference contour (ideal shape) and the actual contour (measured shape). By separately estimating the reference contour using Fourier descriptors and comparing it with the actual contour, the method enables detection of local shape deviations that conventional geometric parameter measurements cannot detect.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transforms the measurement approach from using geometric parameters (width, area, etc.) to using Fourier descriptor parameters. This parameter transformation allows the measurement system to capture shape information in a different mathematical domain, enabling detection of local deviations while maintaining robustness against noise and measurement variations.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If geometric parameters such as average contact diameter are used, then simple measurements can be performed, but correlation with electrical measurements is insufficient

Engineering Contradiction:

Improvecorrelation with electrical measurementsVSAvoidprocess control accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent replaces conventional geometric parameter measurement (mechanical/direct measurement approach) with Fourier descriptor-based contour analysis (mathematical transformation approach). This substitution enables the measurement system to capture subtle shape variations that correlate with electrical performance, providing better process control accuracy without requiring more complex physical measurement equipment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Difficulty of detecting and measuring

If conventional measurement methods are applied, then measurement process is simple, but detection of local shape deviation is inadequate

Engineering Contradiction:

Improveease of detecting local shape deviationVSAvoidaccuracy of shape deviation measurement

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent introduces the Fourier descriptor as an intermediary mathematical representation between the actual measured contour and the reference contour. This intermediary enables systematic comparison of shapes by transforming both contours into the same mathematical domain, making local shape deviations detectable through parameter comparison while maintaining measurement simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11686571B2Local shape deviation in a semiconductor specimen

Publication Date: 2023.06.27 APPL MATERIALS ISRAEL LTD

AI summary

There is provided a system and method of a method of detecting a local shape deviation of a structural element in a semiconductor specimen, comprising: obtaining an image comprising an image representation of the structural element; extracting, from the image, an actual contour of the image representation; estimating a reference contour of the image representation indicative of a standard shape of the structural element, wherein the reference contour is estimated based on a Fourier descriptor representative of the reference contour, the Fourier descriptor being estimated using an optimization method based on a loss function specifically selected to be insensitive to local shape deviation of the actual contour; and performing one or more measurements representative of one or more differences between the actual contour and the reference contour, the measurements indicative of whether a local shape deviation is present in the structural element.