Interferometric Spectroscopy Metrology for Semiconductor Fabrication
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Solution Overview
Problem
Spectral measurements in semiconductor device manufacture are time-consuming, increasing overall processing time and reducing efficiency in metrological activities such as calibration and overlay, necessitating the expedient acquisition of robust spectral information.
Innovation Solution
An interferometric-spectroscopy metrology tool using an interferometric microscope with a single-pixel detector to capture interferograms from white light illumination and apply Fourier transformations, along with a broadband reflector to characterize the spectrum, enabling rapid acquisition of spectral data and hyperspectral imaging by splitting white light into reference and test beams and applying Fourier transforms to generate frequency spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional spectral measurement methods are used during calibration and overlay activities, then robust spectral information is acquired, but processing time increases and fabrication efficiency decreases
Solution Approach 1:
The patent combines overlay measurement and spectral measurement into a single integrated interferometric measurement process. The interferometric microscope simultaneously captures both overlay information and spectral information through white light illumination and interferogram capture, eliminating the need for separate measurement sequences and reducing total processing time while maintaining measurement accuracy.
Solution Approach 2:
The interferometric microscope is designed to perform multiple functions: overlay measurement, spectral characterization, and process monitoring. By using a single instrument that can extract multiple types of information from the same interferogram data, the system eliminates the need for separate dedicated measurement tools and sequences, thereby reducing time loss while providing comprehensive spectral information.
2Measurement precision
If spectral measurements are performed during metrological activities, then accurate spectral characterization is achieved, but overall fabrication speed is reduced
Solution Approach 1:
The system performs spectral characterization as a preliminary action during the overlay measurement sequence. By capturing the interferogram with white light illumination during the existing overlay measurement process, the spectral information is obtained in advance without requiring additional measurement time, thus maintaining fabrication speed while achieving accurate spectral characterization.
Solution Approach 2:
The interferometric measurement process continuously captures both overlay and spectral information simultaneously through white light illumination. The single-pixel detector continuously records interferograms during the measurement sequence, ensuring that spectral characterization is performed continuously without interrupting the fabrication flow, thereby maintaining both accuracy 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
This approach significantly reduces the time required for spectral data acquisition while maintaining fabrication speed and efficiency, providing robust spectral information for metrological activities without impacting overlay measurement time, and facilitating the creation of spectral reflectivity maps for process assessment and recipe creation.
Implementation Method 1
an interferometric microscope configured to create an interferogram from light beams derived from white light illumination during vertical conveyance of a focal lens
Implementation Method 2
the interferogram captured by a single-pixel detector associated with the interferometric microscope
Implementation Method 3
a computer configured to render the interferogram into a frequency spectrum through application of a Fourier transformation on the interferogram
Implementation Method 4
the light beams include a beam reflected from a broadband reflector so as to characterize a spectrum of the white light illumination in the interferogram
Data Source
AI summary
A device and method for expediting spectral measurement in metrological activities during semiconductor device fabrication through interferometric spectroscopy of white light illumination during calibration, overlay, and recipe creation.