Ultrafast LiDAR Inspection with Temporal Gating for Semiconductor Defects
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Solution Overview
Problem
Existing LiDAR technology has limitations due to its resolution limit of several tens of μm, hindering its application in nondestructive inspection of semiconductor devices.
Innovation Solution
A LiDAR-based inspection device utilizing ultrafast pulses with pulse widths ranging from 1 fs to 100 fs, a gating signal with precise time control, and a nonlinear optical generator to generate a nonlinear optical signal, enabling ultrafine resolution of 100 nm or less by monitoring the correlation of chirp and gating signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LiDAR technology is used, then the device complexity is low, but the measurement precision is limited to several tens of μm
Solution Approach 1:
The patent changes the temporal parameter of the light pulse from conventional nanosecond scale to ultrafast femtosecond scale (1-100 fs). This parameter change enables resolution improvement from tens of μm to 100 nm or less by reducing the time-of-flight measurement uncertainty, while the added complexity is confined to the pulse generation and detection subsystems
Solution Approach 2:
The patent introduces dynamic temporal gating using ultrafast optical switching to selectively detect reflected pulses at different time intervals. This dynamic control mechanism allows precise depth resolution by opening the detection window only during the ultrafast pulse return, enabling high resolution without continuously operating complex components
2Measurement precision
If ultrafast pulses with pulse width of 1 fs to 100 fs are used, then the measurement precision improves to 100 nm or less, but the device complexity increases
Solution Approach 1:
The patent employs periodic emission of ultrafast laser pulses combined with periodic gating signals synchronized to the pulse repetition rate. This periodic operation allows the use of simpler components that operate intermittently at high speed rather than continuously, managing complexity through rhythmic operation cycles
Solution Approach 2:
The patent introduces an ultrafast optical gate as an intermediary component that mediates between the ultrafast pulse source and the detector. This gate acts as a temporal window controller, enabling the detector to only receive signals during the precise time window when reflected ultrafast pulses return, thereby achieving high resolution while isolating the detector from continuous high-intensity pulse exposure
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 device achieves ultrafine resolution of 100 nm or less, allowing for precise nondestructive inspection of semiconductor devices, enhancing defect detection and yield in semiconductor manufacturing processes.
Implementation Method 1
an ultrafast pulse source configured to generate a first ultrafast pulse and a second ultrafast pulse each having a pulse width ranging from 1 fs to 100 fs, the first ultrafast pulse and the second ultrafast pulse being coherent with each other
Implementation Method 2
a dispersing device configured to generate a chirp signal, based on the second ultrafast pulse reflected from a specimen, the chirp signal including a plurality of pulses having different wavelengths
Implementation Method 3
a nonlinear optical generator configured to generate a nonlinear optical signal based on the chirp signal and the gating signal, wherein the gating signal temporally overlaps with some of the plurality of pulses included in the chirp signal in the nonlinear optical generator
Implementation Method 4
a detector configured to detect the nonlinear optical signal
Implementation Method 5
a stage configured to adjust a distance of flight of the gating signal transmitted to the nonlinear optical generator
Data Source
AI summary
Provided is a light detection and ranging (LiDAR)-based inspection device including an ultrafast pulse source configured to generate a first ultrafast pulse and a second ultrafast pulse each having a pulse width ranging from 1 fs to 100 fs, a stage configured to generate a gating signal by adjusting a distance of flight of the first ultrafast pulse, a dispersing device configured to generate a chirp signal, based on the second ultrafast pulse reflected from a specimen, the chirp signal including a plurality of pulses having different wavelengths, a nonlinear optical generator configured to generate a nonlinear optical signal based on the chirp signal and the gating signal, and a detector configured to detect the nonlinear optical signal, wherein the gating signal temporally overlaps with some of the plurality of pulses included in the chirp signal in the nonlinear optical generator.