Electron Microscope Inclined Hole Measurement

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Solution Overview

Problem

Existing methods for measuring the inclination of high-aspect holes in DRAM or 3D-NAND semiconductor wafers fail to accurately determine the inclination when the hole bottom is blocked by the sample surface, leading to incorrect measurements due to the contour of the hole bottom being obscured.

Innovation Solution

An electron microscope device with separate detection units for low-energy and high-energy electrons, allowing for the calculation of inclination angles by processing images from both units to determine the inclined orientation and angle of the hole regions, even when the hole bottom is blocked by the surface layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a top view image is used to measure hole inclination, then the measurement process is simple, but the hole bottom contour is blocked and cannot be detected correctly

Engineering Contradiction:

Improvemeasurement process simplicityVSAvoidhole bottom contour detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent transitions from two-dimensional top view imaging to three-dimensional surface shape measurement by detecting electron emission intensity variations at multiple positions. This dimensional change allows the system to perceive depth information and hole bottom contours that are invisible in conventional top view images, enabling accurate inclination measurement without being blocked by the sample surface.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces electron emission intensity as an intermediary parameter to indirectly detect the hole bottom contour. Instead of directly imaging the blocked hole bottom, the system measures electron emission intensity at multiple positions around the hole, which varies according to the surface shape and hole inclination, thereby revealing the hidden hole bottom information.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the hole bottom contour is used to calculate inclination, then accurate measurement is possible, but the contour is blocked by the sample surface and cannot be detected

Engineering Contradiction:

Improveinclination measurement accuracyVSAvoidhole bottom contour visibility

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent replaces the mechanical/optical imaging system with an electron emission detection system. Instead of using conventional imaging to directly view the hole bottom contour, the system uses electron beam irradiation and detects variations in electron emission intensity, which are influenced by the hole's surface shape and inclination, thereby obtaining contour information that is otherwise invisible.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from direct optical imaging to electron emission intensity measurement. By irradiating the sample with electrons and measuring the emission intensity at multiple positions, the system obtains information about the hole bottom contour through parameter transformation, overcoming the limitation of direct visual blocking.

Inventive Principle:

Principle #35Parameter changes

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 accurate measurement of hole inclination from top view images, preventing underestimation of the actual inclination and allowing for precise determination of hole orientation and angle, even in cases where the hole bottom is obscured.

Implementation Method 1

a first detection unit disposed at a high elevation angle and configured to detect electrons having relatively low energy among electrons generated from the semiconductor wafer on which the hole is formed due to a primary electron beam irradiated on the semiconductor wafer

Methodology Applied

Scientific EffectElectron emission: Photoelectric Effect

Implementation Method 2

a second detection unit disposed at a low elevation angle and configured to detect electrons having relatively high energy among the electrons generated from the semiconductor wafer due to the primary electron beam irradiated on the semiconductor wafer

Methodology Applied

Scientific EffectBackscattered electron detection: Compton Scattering

Data Source

PatentUS10720307B2Electron microscope device and inclined hole measurement method using same

Publication Date: 2020.07.21 HITACHI HIGH TECH CORP

AI summary

An electron microscope device includes: a first detection means disposed at a high elevation angle for detecting electrons having relatively low energy; a second detection means disposed at a low elevation angle for detecting electrons having relatively high energy; a means for identifying, from a first image obtained from a first detector, a hole region in a semiconductor pattern within a preset region; a means for calculating for individual holes, from a second image obtained from a second detector, indexes pertaining to an inclined orientation and an inclination angle, on the basis of the distance between the outer periphery of the hole region and the hole bottom; and a means for calculating, from the results measured for the individual holes, indexes pertaining to an inclined orientation of the hole and an inclination angle of the hole as representative values for the image being measured.