Self-Interference Optical System for Sub-Diffraction Semiconductor Metrology
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges due to shrinking design rules and reduced pattern sizes, leading to resolution issues and decreased measurement accuracy in existing measurement devices.
Innovation Solution
An image measurement device is developed, comprising an optical system that transmits light to an image detection unit and an image processing unit that extracts spectral data. The optical system includes a relay lens and a self-interference structure with a polarizer and retarder, which self-interferes the light. The image processing unit generates a profile based on light intensity for each pixel, performs Fourier transform to separate frequency regions, and applies windowing and zoom Fast Fourier Transform to extract high-resolution spectral data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement devices are used for smaller pattern sizes, then device complexity remains low, but measurement precision deteriorates due to resolution issues
Solution Approach 1:
The measurement device is divided into distinct functional modules: an optical system for light transmission and interference, an image detection unit for capturing interference patterns, and an image processing unit for spectral data extraction. This segmentation allows each module to be optimized independently, improving measurement precision without proportionally increasing overall device complexity.
Solution Approach 2:
The invention transitions from direct spatial measurement to spectral domain measurement by capturing interference patterns and performing Fourier transform. This dimensional change from real space to frequency space enables resolution of fine pattern details that are below the diffraction limit of conventional optical systems.
2Manufacturing precision
If the pattern size is reduced to meet shrinking design rules, then manufacturing precision is improved, but measurement precision deteriorates due to resolution limitations
Solution Approach 1:
An interference pattern acts as an intermediary between the small pattern features and the measurement system. The self-interference structure creates magnified interference fringes that encode information about sub-resolution features, allowing indirect measurement of patterns smaller than the optical resolution limit.
Solution Approach 2:
The invention changes the measurement parameter from direct spatial resolution to spectral frequency analysis. By performing Fourier transform on the interference pattern, the system converts spatial frequency information into measurable spectral data, enabling accurate measurement of features below the diffraction limit.
3Measurement precision
If spectral data extraction is enhanced for better measurement accuracy, then measurement precision is improved, but processing time increases
Solution Approach 1:
The system performs preliminary action by capturing the complete interference pattern in a single shot and pre-processing the image data to generate intensity profiles. This preliminary processing organizes the data in a way that enables efficient subsequent spectral extraction, reducing the computational burden and processing time.
Solution Approach 2:
The image processing unit dynamically adjusts processing parameters based on the input image characteristics. The system adaptively selects processing algorithms and parameters to optimize the balance between spectral data accuracy and processing time, allowing fast processing when high precision is not critical and more thorough processing when accuracy is paramount.
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
The solution enhances measurement accuracy and resolution, enabling effective monitoring of semiconductor device properties despite shrinking pattern sizes, by improving the extraction and analysis of spectral data.
Implementation Method 1
a self-interference structure configured to self-interfere the light
Implementation Method 2
a polarizer that polarizes the light
Implementation Method 3
a retarder that delays the phase of the light
Implementation Method 4
the image detection unit configured to detect the light and generate an image
Implementation Method 5
performs Fourier transform on the profile, the image processing unit separates the profile into a high-frequency region and a low-frequency region
Data Source
AI summary
An image measurement device includes an optical system that transmits light output to an image detection unit, the image detection unit configured to detect the light and generate an image, and an image processing unit that extracts spectral data from the image, wherein the image processing unit generates a profile according to an amount of light for each of a plurality of pixels based on the image, and performs Fourier transform on the profile.