SWIR Focus Averaging for Patterned Substrate Inspection
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Solution Overview
Problem
Existing SWIR inspection systems struggle to precisely detect the locations of features on patterned substrates due to varying optimal foci across different SWIR wavelengths, especially in high-magnification applications, and implementing multiple image capture devices is costly and inefficient.
Innovation Solution
A SWIR inspection system using focus averaging generates multiple SWIR waves of varying wavelengths through a common optical fiber, combining them with a single image sensor to create a focus-averaged image, controlled by a controller that synchronizes wave generation with substrate motion to improve scanning throughput and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple image capture devices are used to capture images at different SWIR wavelengths, then detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple image capture devices into a single device that can detect multiple SWIR wavelengths simultaneously. This is achieved by using a single imaging sensor with optical filters or a tunable filter system that allows the same sensor to capture images at different wavelengths, thereby maintaining detection accuracy while reducing device complexity and cost.
Solution Approach 2:
The single image capture device is designed to perform multiple functions by capturing images across different SWIR wavelengths. The device incorporates wavelength-selective optical elements that enable it to detect various wavelengths using the same sensor, making it a universal imaging device that replaces what would traditionally require multiple specialized devices.
2Measurement precision
If multiple image capture devices are used to capture images at different SWIR wavelengths, then detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the functionality of multiple expensive image capture devices into a single, more cost-effective device. By using one imaging sensor with wavelength-selective optical filters instead of multiple dedicated sensors, the system significantly reduces manufacturing costs while preserving the ability to detect features across different SWIR wavelengths with high accuracy.
Solution Approach 2:
Instead of purchasing and deploying multiple physical image capture devices, the patent uses a single device that replicates the functionality of multiple devices through software-controlled optical filtering. The same sensor captures images at different wavelengths by sequentially applying different optical filters, creating a cost-effective copy of what would otherwise require multiple hardware devices.
3Measurement precision
If focus is optimized for each SWIR wavelength, then image quality is improved, but scanning throughput decreases due to the need for multiple focus adjustments
Solution Approach 1:
The patent performs preliminary focus optimization for all SWIR wavelengths before the actual inspection process. By pre-determining the optimal focus settings for each wavelength and storing these calibration data, the system eliminates the need for real-time focus adjustments during scanning, thereby maintaining high image quality across all wavelengths while maximizing scanning throughput.
Solution Approach 2:
The patent implements a dynamic focus adjustment mechanism that automatically switches between pre-calibrated focus settings based on the currently active wavelength. The system dynamically selects the appropriate focus value from stored calibration data corresponding to the wavelength being used, enabling rapid wavelength switching without mechanical focus adjustments, thus preserving both image quality and scanning speed.
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 focus margin and detection accuracy while reducing costs by using a single image capture device, enabling more effective imaging and inspection of patterned substrates with improved scanning throughput and image quality.
Implementation Method 1
generates multiple SWIR waves of varying wavelengths through a common optical fiber
Implementation Method 2
a SWIR imaging system including an optical system and at least one image capture device operatively coupled with at least one image sensor
Implementation Method 3
inspect the patterned substrate by focus averaging a plurality of images of the patterned substrate. Each image of the plurality of images corresponds to a respective SWIR wavelength
Data Source
AI summary
A system includes a memory and at least one processing device, operatively coupled with the memory, to obtain metrology data with respect to a substrate, cause a lithography process to be performed using the metrology data to obtain a patterned substrate to be processed, and after performing the lithography process, cause a shortwave infrared (SWIR) inspection system to inspect the patterned substrate by focus averaging a plurality of images of the patterned substrate. Each image of the plurality of images corresponds to a respective SWIR wavelength of a plurality of SWIR wavelengths.