Terahertz Inspection Apparatus Layer Boundary Estimation
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Solution Overview
Problem
The existing terahertz wave inspection apparatus requires a high processing cost to estimate the thickness of layers, which is equivalent to estimating the position of boundary surfaces, as it compares detected waveforms with multiple estimated waveforms for various parameters.
Innovation Solution
An inspection apparatus and method that irradiates a terahertz wave to a sample with laminated layers, detects the wave, selects a portion of a library based on the detected waveform, and estimates the boundary surface position using the selected library, reducing the need to compare with all estimated waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the terahertz wave inspection apparatus compares the detected waveform with all estimated waveforms for multiple parameters, then the measurement precision for estimating layer thickness and boundary surface position is improved, but the processing cost and time consumption increase significantly
Solution Approach 1:
The patent segments the estimation process into two stages: first selecting candidate waveforms from a library based on waveform characteristics, then performing precise estimation only on the selected candidates. This segmentation reduces the computational burden while maintaining accuracy by focusing processing on the most relevant waveforms rather than all possible estimated waveforms.
Solution Approach 2:
The patent employs preliminary action by pre-storing estimated waveforms for multiple parameters in a library before actual measurement. During measurement, the system selects appropriate waveforms from this pre-prepared library based on detected waveform characteristics, avoiding the need to compute and compare all possible estimated waveforms in real-time, thus reducing processing time while maintaining precision.
2Measurement precision
If the inspection apparatus compares detected waveform with multiple estimated waveforms for different parameters, then the measurement precision is improved, but the device complexity and processing cost increase
Solution Approach 1:
The patent extracts and stores only the necessary estimated waveforms in a library structure, organized by parameters. During measurement, the system extracts and compares only the relevant waveforms based on detected characteristics, rather than processing all possible estimated waveforms. This extraction approach reduces processing complexity while maintaining the ability to achieve high measurement precision for thickness and boundary surface position estimation.
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 allows for accurate estimation of boundary surface positions with a significantly reduced processing cost, saving time and resources compared to existing methods.
Implementation Method 1
a pump light (in other words, an excitation light) is irradiated to a terahertz wave generating element to which a bias voltage is applied, wherein the pump light is one laser light that is obtained by branching an ultrashort pulse laser light
Implementation Method 2
the terahertz wave detecting element detects the terahertz wave reflected by or transmitted through the sample
Data Source
AI summary
An inspecting device is provided with: a radiating unit which radiates terahertz waves onto a sample laminated into a plurality of layers; a detecting unit which acquires a detected waveform by detecting terahertz waves from the sample; a selecting unit which selects a portion of a library representing an estimated waveform, on the basis of the detected waveform; and an estimating unit which estimates a position of an interface between the plurality of layers, on the basis of the detected waveform and the selected partial library.