Optical Acoustic Substrate Assessment System
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Solution Overview
Problem
Current optical acoustic metrology systems face limitations in effectively assessing internal features and defects in semiconductor substrates, such as cracks, delaminations, and voids, which are crucial for quality control and reliability in semiconductor fabrication.
Innovation Solution
The system induces surface acoustic waves at multiple locations on a semiconductor substrate, measuring the time it takes for these waves to travel and interact with structures, allowing for the determination of structural characteristics like location, solidity, and continuity, using a combination of pump and probe lasers with a controller to manage temporal spacing and sensor data analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic waves are used to penetrate solid materials for nondestructive measurement, then internal features and defects can be detected, but the system complexity and measurement precision requirements increase
Solution Approach 1:
The system segments the measurement process by using multiple discrete laser beams (pump and probe beams) that can be independently controlled and positioned. Each beam performs a specific function: the pump beam generates acoustic waves while the probe beam detects surface displacements. This segmentation allows the complex measurement task to be divided into manageable components, reducing overall system complexity while maintaining high reliability for detecting internal features and defects.
Solution Approach 2:
The patent introduces surface acoustic waves as an intermediary mechanism to indirectly probe internal structures. Instead of directly imaging internal features, the system uses acoustic waves that propagate through the material and interact with internal defects, causing detectable surface displacements. This intermediary approach enables nondestructive detection of internal features while using optical measurement techniques, balancing reliability with manageable system complexity.
2Measurement precision
If multiple measurement locations are used to assess structures, then measurement precision improves, but measurement time increases
Solution Approach 1:
The system employs periodic action by rapidly alternating between pump and probe laser operations at multiple measurement locations. The pump laser periodically generates acoustic waves while the probe laser periodically measures surface displacements. This periodic operation allows the system to efficiently cycle through multiple measurement points, collecting precise data from each location while minimizing total measurement time through optimized timing and sequencing.
Solution Approach 2:
The patent applies preliminary action by first establishing the temporal spacing and synchronization of pump and probe laser operations before actual measurements begin. The system pre-configures the measurement sequence, positioning and timing parameters, and data collection protocols. This preliminary setup enables rapid execution of multi-location measurements without requiring real-time adjustments, thereby improving measurement precision across multiple locations while reducing overall measurement time.
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 method enables non-destructive assessment of semiconductor structures, providing accurate information on structural dimensions and defects, enhancing quality assurance and process control in semiconductor manufacturing.
Implementation Method 1
inducing at least a surface acoustic wave at a first location of a surface of a substrate
Implementation Method 2
The absorption of at least a portion of the radiant energy of the pump beam by the substrate induces a surface acoustic wave
Implementation Method 3
changes in an intensity of the probe beam returned from the substrate are measured
Implementation Method 4
The surface acoustic wave will at least partially interact with the structure formed in the substrate as it moves from the first to the second location
Data Source
AI summary
A system and method for identifying one or more characteristics of a structure formed into a substrate is herein disclosed. Surface and bulk acoustic waves are induced in the substrate and travel past a structure of interest where the acoustic waves are sensed. Information concerning one or more characteristics of the structure is encoded in the wave. The encoded information is assessed to determine the characteristic of interest.