Through-Focus Metrology for Non-Destructive Pattern Quantification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current metrology techniques, such as OCD and TEM, are either unable to measure non-repetitive patterns smaller than the beam size or require destructive sampling, making it challenging to perform non-destructive metrology on narrow regions with high precision.
Innovation Solution
A through-focus image-based metrology device that uses an optical device with a stage, image sensor, and light source to acquire multiple images at different focal positions, generating an intensity profile and employing a learning model to quantify metrology data without damaging the target, enabling non-destructive measurement of non-repetitive patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional metrology techniques (OCD, TEM) are used to measure small patterns, then measurement precision may be achieved, but the target cannot be measured non-destructively or non-repetitive patterns smaller than beam size cannot be quantified
Solution Approach 1:
The patent creates a virtual copy of the physical target by acquiring through-focus images at multiple focal positions and generating a three-dimensional image data space. This virtual model allows non-destructive metrology of non-repetitive patterns without requiring physical access or destruction of the original target. The intensity profile extracted from this virtual model enables precise measurement while preserving the actual target.
2Loss of information
If through-focus scanning optical microscopy is used to acquire scattered interference information, then three-dimensional image data can be created, but the process is complex and time-consuming
Solution Approach 1:
The patent performs preliminary action by acquiring through-focus images at multiple predetermined focal positions before extracting the intensity profile. This pre-acquisition of multi-focal data creates a complete three-dimensional image data space that can be later analyzed to extract precise metrology information, avoiding the need for repeated measurements and reducing total analysis time.
Solution Approach 2:
The patent transitions from two-dimensional single-focus imaging to three-dimensional through-focus imaging by adding the focal position dimension. This dimensional expansion captures scattered interference information more effectively, allowing the extraction of intensity profiles that contain rich metrology information about the target structure.
3Measurement precision
If destructive sampling methods are used to achieve high precision measurement, then measurement accuracy improves, but the target is damaged and cannot be reused
Solution Approach 1:
The patent measures the target through its optical interaction (reflected light) rather than physical contact or destruction. The intensity profile is extracted from optical images, creating a measurement copy of the target's structural information without affecting the physical target. This enables repeated non-destructive measurements of the same target.
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 precise, non-destructive metrology of small non-repetitive patterns with high resolution, overcoming the limitations of existing methods by using intensity profiles and learning models to analyze through-focus images for metrology data generation.
Implementation Method 1
an objective lens disposed between the image sensor and the stage, the objective lens being configured to transmit reflected light from the target
Implementation Method 2
a light source configured to emit illumination light to the target through the objective lens
Data Source
AI summary
Provided is a through-focus image-based metrology device including an optical device, and a computing device configured to acquire at least one through-focus image of a target from the optical device, generate an intensity profile based on the acquired at least one through-focus image, and perform metrology on the target based on the generated intensity profile, wherein the optical device includes a stage on which the target is disposed, the stage being configured to move by one step in at least one direction based on control of the computing device, and to acquire the at least one through-focus image, an image sensor disposed on the stage, an objective lens disposed between the image sensor and the stage, the objective lens being configured to transmit reflected light from the target, and a light source configured to emit illumination light to the target through the objective lens.