Periodic Reflective Sample Inspection for Fab Deviation Detection
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Solution Overview
Problem
Current inspection methods for semiconductor manufacturing, such as SEM and optical scatterometry, face limitations due to noise, speed, charging issues, and low signal-to-noise ratios, making it difficult to accurately determine fabrication process deviations and calibrate the process effectively.
Innovation Solution
A method and tool that utilize a sample with a periodic structure designed to be fully reflective for specific wavelengths and angles, allowing for the detection of light reflected or transmitted to determine fabrication process deviations, and generate correction signals for process calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SEM or optical scatterometric techniques are used for inspection, then manufacturing capability is maintained, but measurement precision deteriorates due to noise, charging issues, and low signal-to-noise ratios
Solution Approach 1:
The periodic structure is designed and fabricated in advance with specific optical properties (fully reflective at certain wavelengths and angles) to enhance the inspection signal. This preliminary structuring of the sample enables improved measurement precision without requiring changes to the inspection methodology itself.
Solution Approach 2:
The invention utilizes optical reflectivity properties of the periodic structure at specific wavelengths and angles of incidence. By designing the structure to be fully reflective under specific optical conditions, the method enhances the signal strength and improves the signal-to-noise ratio for deviation detection.
2Measurement precision
If conventional inspection methods are used, then device complexity is maintained, but measurement precision deteriorates due to inherent limitations of the inspection tools
Solution Approach 1:
The invention uses a periodic structure that creates a characteristic optical response (full reflectivity at specific wavelengths and angles) as a reference or fingerprint. This optical signature serves as a copy or representation of the fabrication quality, allowing indirect measurement of deviations without requiring direct physical measurement of each feature.
3Measurement precision
If standard fabrication inspection is performed, then productivity is maintained, but measurement precision deteriorates due to the need for multiple measurements and recalibrations
Solution Approach 1:
The periodic structure is fabricated as part of the standard manufacturing process in advance, embedding the calibration reference directly into the product. This eliminates the need for separate calibration procedures and repeated measurements, thereby improving both measurement precision and productivity.
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
Enhances the accuracy of fabrication process deviation detection and calibration by utilizing a fully reflective periodic structure to improve signal quality, enabling precise adjustments and reducing errors in semiconductor manufacturing.
Implementation Method 1
a layer having a periodic structure fabricated using the fabrication process and intended to cause a corresponding part of the layer to be fully reflective for light having a wavelength in a wavelength range and having an angle of incidence in an angle range
Implementation Method 2
a layer having a periodic structure fabricated using the fabrication process
Data Source
AI summary
A method for determining deviations in a fabrication process, the method including: providing a sample with a layer having a periodic structure fabricated using the fabrication process and intended to cause a corresponding part of the layer to be fully reflective for light having a wavelength in a wavelength range and having an angle of incidence in an angle range; illuminating the sample with light having a wavelength in the wavelength range and an angle of incidence in the angle range; detecting light reflected and/or scattered from the layer of the sample; and determining deviations in the fabrication process from the detected light.