SHG Metrology with Pump-Probe Lasers for Defect Quantification
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Solution Overview
Problem
Existing SHG-based metrology tools face limitations in distinguishing between interfacial properties and quantifying contaminants, such as differentiating between gettered contaminants and bond voids, due to their reliance on relative measurements rather than precise quantitative analysis.
Innovation Solution
The use of a pump and probe system with a high average power, low peak power pump laser and a high peak power, low average power probe laser to generate and analyze SHG signals, allowing for faster and more accurate determination of threshold energy for carrier injection and enabling the differentiation and quantification of defects and contaminants by monitoring transient electric field decay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SHG-based metrology tools use relative measurements, then the measurement process is simple, but the ability to distinguish between interfacial properties and quantify contaminants is limited
Solution Approach 1:
The patent segments the measurement process into distinct phases using pump and probe laser beams with different functions. The pump beam prepares the sample state while the probe beam performs the actual measurement, allowing separate optimization of each function and enabling precise quantification without overwhelming system complexity
Solution Approach 2:
The patent introduces transient electric field decay as an intermediary phenomenon that mediates between the laser excitation and the final measurement signal. This intermediary provides a time-resolved signature that enables precise differentiation and quantification of contaminants while maintaining manageable system complexity through temporal separation
2Measurement precision
If a single high power laser is used for SHG measurement, then the system is simpler to operate, but the ability to determine threshold energy and differentiate defect types is reduced
Solution Approach 1:
The patent divides the laser system into two specialized beams: a pump laser optimized for inducing transient electric field decay and a probe laser optimized for detecting SHG signals. This segmentation allows each beam to be optimized for its specific function, improving defect differentiation precision while the automated sequencing maintains operational simplicity
Solution Approach 2:
The patent employs periodic pumping and probing cycles with controlled time intervals. The pump beam excites the sample at regular intervals, and the probe beam measures the transient decay at predetermined times. This periodic action enables precise threshold energy determination and defect type differentiation through temporal signal analysis
3Measurement precision
If fast transient electric field decay monitoring is implemented, then real-time quantification of contaminants is enabled, but the measurement and processing time increases
Solution Approach 1:
The patent performs preliminary action by having the pump laser prepare the sample state in advance before the probe laser performs the actual measurement. This pre-excitation creates a transient electric field decay signature that contains the contamination information, allowing the probe to quickly capture the signal without requiring prolonged measurement times
Solution Approach 2:
The patent uses periodic pumping and probing with optimized cycle times. By repeating the measurement cycle at appropriate intervals and capturing the transient decay at specific time points, the system achieves precise contaminant quantification while maintaining efficient throughput through temporal multiplexing
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 enables real-time or post-processing quantification of defect types and contaminant species, providing precise data for process adjustments and improving semiconductor device fabrication quality.
Implementation Method 1
Second-Harmonic generation is a non-linear optical effect comprising conversion of light having one frequency into light at twice that frequency upon scattering from some types of materials, structures, and geometries
Implementation Method 2
determination of threshold energy for carrier injection and enabling the differentiation and quantification of defects and contaminants by monitoring transient electric field decay
Data Source
AI summary
Systems and methods are disclosed for using second-harmonic generation of light to monitor the manufacturing process for changes that can affect the performance or yield of produced devices and/or determining critical dimensions of the produced device.