AFM Critical Dimension Measurement for High-Aspect-Ratio Trenches
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Solution Overview
Problem
Conventional Atomic Force Microscopes (AFMs) face challenges in measuring the Critical Dimensions (CDs) of semiconductor structures with high aspect ratio trenches, as the probe can damage the structure during measurement due to contact with the trench sidewalls.
Innovation Solution
The method involves controlling the AFM probe to maintain a specific distance from the semiconductor surface, scanning while detecting amplitudes at scanning points, and using amplitude thresholds to determine CD without requiring interaction force detection, thus avoiding probe descent into trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the AFM probe is controlled to oscillate close to the surface (5nm to 10nm above) to achieve high measurement accuracy, then measurement precision is improved, but the probe may contact the sidewall of high aspect ratio trenches and damage the semiconductor structure
Solution Approach 1:
The patent introduces amplitude thresholds as an intermediary criterion to mediate between the probe position and the trench structure. By comparing probe oscillation amplitudes at different positions against predetermined thresholds, the system can identify trench boundaries and adjust the measurement path without direct contact, thus maintaining measurement accuracy while preventing structure damage
Solution Approach 2:
The patent replaces the traditional mechanical interaction-based measurement (detecting interaction force between probe and surface) with an amplitude-based detection method. By monitoring changes in probe oscillation amplitude rather than relying on contact force, the system can detect trench features and determine critical dimensions without mechanical contact, eliminating the harmful effect of probe-sidewall contact
2Object-affected harmful factors
If the probe reaches a certain distance from the trench surface to avoid contact, then structure damage is prevented, but measurement precision deteriorates due to increased distance from the surface
Solution Approach 1:
The patent transitions from measuring only in the vertical dimension (distance from surface) to incorporating horizontal dimension information through amplitude comparison. By scanning across the trench and comparing amplitudes at different lateral positions, the system can determine trench boundaries and critical dimensions using amplitude ratios, effectively adding a dimensional approach that maintains precision without requiring close proximity to the trench sidewalls
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 prevents damage to the semiconductor structure and allows accurate CD measurement of high aspect ratio trenches, expanding the AFM's applicability to structures like photoresistors.
Implementation Method 1
a probe of the AFM is controlled to oscillate at a position 5nm to 10nm above the surface of the semiconductor structure
Implementation Method 2
amplitudes of the probe at respective scanning points on the top surface of the semiconductor structure to be measured are detected
Data Source
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AI summary
The embodiments of the present disclosure provide a method and evice for measuring dimension of a semiconductor structure. In a measurement process, a probe of an Atomic Force Microscope (AFM) is controlled at first to move a first distance from a preset reference position to a top surface of a semiconductor structure to be measured in a direction perpendicular to the top surface of the semiconductor structure to be measured, then the probe is controlled to scan the surface of the semiconductor structure to be measured while keeping the first distance in a direction parallel to the top surface of the semiconductor structure to be measured, amplitudes of the probe at respective scanning points on the surface of the semiconductor structure to be measured are detected, and a Critical Dimension (CD) of the semiconductor structure to be measured is determined according to the amplitudes of the probe at respective scanning points on the surface of the semiconductor structure to be measured. According to the present disclosure, when there is a high-aspect-ratio trench in the surface of the semiconductor structure to be measured, damages to the semiconductor structure to be measured may be avoided, a measurement manner is simple, influences of a surface structure of the semiconductor structure to be measured are eliminated, and the present disclosure range is wider.