Charged Particle Microscope Image Correction for Buried Patterns

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Solution Overview

Problem

Conventional scanning electron microscopes (SEM) cannot accurately inspect or measure buried layer patterns due to resolution degradation caused by electron beam diffusion in the sample's surface layer, limiting their ability to observe internal patterns with high precision.

Innovation Solution

A charged particle microscope apparatus that includes a radiation optical system to focus a charged particle beam on the sample, a detection system to capture and process the charged particles, and a processing unit to estimate and correct for electron diffusion based on pattern depth and material information, thereby improving image quality and precision of lower layer pattern observation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If high energy electron beam is used to observe lower layer patterns, then observation capability of buried patterns is improved, but space resolution is degraded due to electron diffusion

Engineering Contradiction:

Improveobservation capability of buried patternsVSAvoidspace resolution

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent converts the harmful effect of electron diffusion into a useful signal by detecting the diffused electrons and using their distribution patterns to reconstruct images of buried patterns. The diffusion that previously degraded resolution is now utilized to reveal subsurface structures through specialized detection and image processing techniques

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces an intermediary image processing step that acts as a mediator between the diffused electron signal and the final image. By applying deconvolution algorithms and diffusion modeling, the system reconstructs the original pattern information from the blurred electron distribution, effectively separating the useful signal from the diffusion-induced blur

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of information

If electron beam energy is increased to penetrate surface layer, then information on buried patterns is obtained, but diffusion in surface layer degrades image quality

Engineering Contradiction:

Improveinformation on buried patternsVSAvoidimage quality

Core Design Contradiction:

Loss of informationVSMeasurement precision

Solution Approach 1:

The patent transforms the information loss caused by electron diffusion into recoverable data by detecting the spatial distribution of diffused electrons. The diffusion process, while blurring the direct beam path, creates a characteristic electron distribution pattern that encodes information about the buried pattern's depth and structure, which is then decoded through specialized image processing

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent employs feedback mechanisms in the form of iterative image reconstruction algorithms that use detected electron distribution data to refine and correct the final image. The system continuously adjusts the reconstructed image based on the actual electron detection signals, compensating for diffusion effects and improving image quality through multiple processing iterations

Inventive Principle:

Principle #23Feedback

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-quality inspection and measurement of lower layer patterns with enhanced image resolution and precision, correcting for the degradation caused by electron diffusion and allowing for accurate observation of internal patterns in multilayer structures.

Implementation Method 1

a radiation optical system that radiates a focused charged particle beam to an upper side of a sample provided with a pattern and scans the sample with the charged particle beam

Methodology Applied

Scientific EffectElectron beam: Electron Beam

Implementation Method 2

a detection optical system that detects charged particles generated from the sample to which the charged particle beam has been radiated

Methodology Applied

Scientific EffectCharged particle generation: Electron Impact Desorption

Implementation Method 3

estimates diffusion of the charged particles at any depth of the pattern of the sample on the basis of information on a depth or a material of the pattern of the sample

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS9190240B2Charged particle microscope apparatus and image acquisition method of charged particle microscope apparatus utilizing image correction based on estimated diffusion of charged particles

Publication Date: 2015.11.17 HITACHI HIGH TECH CORP

AI summary

A charged particle microscope apparatus includes a radiation optical system that radiates a focused charged particle beam to an upper side of a sample provided with a pattern and scans the sample; a detection optical system that detects charged particles generated from the sample to which the charged particle beam has been radiated by the radiation optical system; and a processing unit that processes the charged particles detected by the detection optical system to obtain a charged particle image of the sample, estimates diffusion of the charged particles at any depth of the pattern of the sample, on the basis of information on a depth or a material of the pattern of the sample or radiation energy of the charged particle beam in the radiation optical system; corrects the obtained charged particle image using the estimated diffusion of the charged particles; and processes the corrected charged particle image.