SEM Calibration Sample with Uniform Flat-Top Patterns for Distortion Correction
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Solution Overview
Problem
Conventional scanning electron microscope (SEM) measurement techniques face challenges in achieving high precision and stability due to variations in pattern height and irregularities in calibration samples, leading to decreased measurement accuracy and increased costs, especially as semiconductor devices become smaller and more complex.
Innovation Solution
An image processing method and charged particle beam apparatus adjustment sample with uniform, flat-top projection and depression patterns on a substrate are used to measure and correct for local distortions, allowing for precise adjustment of the SEM, enabling high-precision measurement and calibration without the need for standard samples with calibrated dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration samples with periodic structures are used for SEM measurement, then measurement standardization is achieved, but measurement precision decreases due to pattern height variations and irregularities
Solution Approach 1:
The patent applies local quality by creating projection patterns with uniform height and flat tops in specific measurement regions, while allowing other areas to have varying characteristics. This ensures that the calibration region has consistent local properties (uniform height, flat top) that eliminate measurement variations caused by pattern irregularities, directly resolving the contradiction between measurement precision and stability.
Solution Approach 2:
The patent changes the geometric parameters of the calibration patterns by forming projections with controlled height uniformity and flat-top morphology through specific etching processes. By modifying the pattern geometry to have uniform height and flat tops rather than varying heights, the measurement precision and stability are improved without requiring expensive standard samples.
2Measurement precision
If multiple images are used for distortion correction, then measurement accuracy improves, but productivity decreases due to increased processing time
Solution Approach 1:
The patent applies preliminary action by pre-forming projection patterns with uniform height and flat tops during the sample fabrication process before measurement. This preliminary structuring eliminates the need for multiple images and complex post-processing distortion corrections, as the uniform patterns inherently provide stable reference points for single-image measurement, thus improving productivity while maintaining accuracy.
3Measurement precision
If expensive standard samples with calibrated dimensions are used, then calibration precision improves, but manufacturing costs increase
Solution Approach 1:
The patent replaces expensive, fragile standard samples with inexpensive semiconductor wafers that have projection patterns formed through standard semiconductor fabrication processes. These disposable-like calibration samples can be manufactured at low cost using existing manufacturing capabilities, eliminating the need for costly imported standard samples while maintaining calibration precision through the uniform projection patterns.
Solution Approach 2:
The patent changes the material and structural parameters of calibration samples from expensive specialized standards to inexpensive semiconductor wafers with uniformly structured projections. By controlling the geometric parameters (uniform height, flat top) through fabrication process parameters rather than relying on expensive pre-calibrated samples, calibration precision is achieved at low manufacturing cost.
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 precise and stable measurement and calibration of SEMs, reducing measurement variations and costs by allowing for distortion correction and pattern evaluation with fewer images, thus improving productivity and reducing the need for expensive calibration samples.
Implementation Method 1
a convergent lens and an objective lens that narrows down the electron beam through interaction between the electron beam and a magnetic or electric field
Implementation Method 2
a detector that detects a secondary signal (a secondary electron, a reflection electron or an electromagnetic wave) emitted from the sample irradiated with the electron beam by making use of the photoelectric effect or the like, and forms a sample image by transforming or processing the detected signal into a visualizable signal, such as a brightness signal
Data Source
AI summary
An object of the present invention is to provide an image processing apparatus that quickly and precisely measures or evaluates a distortion in a field of view and a charged particle beam apparatus. To attain the object, an image processing apparatus or the like is proposed which acquires a first image of a first area of an imaging target and a second image of a second area that is located at a different position than the first area and partially overlaps with the first area and determines the distance between a measurement point in the second image and a second part of the second image that corresponds to a particular area for a plurality of sites in the overlapping area of the first image and the second image.