Second Harmonic Wafer Scanning for Quantitative Defect Localization
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Solution Overview
Problem
Current second harmonic measurement technologies face challenges in achieving high measurement efficiency, high resolution, and low material loss in semiconductor wafer processing, as they struggle with whole-area measurement, accurate defect localization, and quantitative analysis due to limitations in measurement accuracy and noise reduction.
Innovation Solution
A second harmonic scanning technology that combines fixed-point and scanning measurements, allowing for real-time control of light spot shape, size, and intensity, and internal charge distribution, enabling whole-area measurement and precise defect localization, while reducing noise through data reprocessing and noise reduction techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed-point measurement is used, then measurement accuracy is improved, but measurement efficiency and productivity deteriorate due to inability to measure whole area
Solution Approach 1:
The measurement process is segmented into multiple scanning lines across the wafer surface. Each line is measured sequentially by moving the light spot along the line, and multiple lines are combined to achieve whole-area coverage. This segmentation allows the system to maintain fixed-point measurement accuracy while extending coverage to the entire wafer surface.
Solution Approach 2:
The measurement approach transitions from a single fixed-point in two dimensions to a two-dimensional scanning grid by adding spatial coordinates (x, y) across the wafer surface. The light spot position is controlled to scan systematically across multiple lines, transforming a point measurement into an area measurement through dimensional expansion.
2Productivity
If scanning measurement is implemented for whole-area coverage, then productivity is improved, but measurement precision deteriorates due to noise and initial value accuracy issues
Solution Approach 1:
Multiple scanning line measurements are merged and averaged to produce the final whole-area measurement result. By combining data from multiple scans and applying noise reduction algorithms, the system maintains high measurement accuracy while achieving efficient whole-area coverage through scanning.
Solution Approach 2:
The system incorporates feedback mechanisms where measurement data from previous scans is used to optimize subsequent scanning parameters. Noise reduction techniques and initial value corrections are applied based on feedback from the scanning process itself, improving measurement precision while maintaining scanning efficiency.
3Measurement precision
If light spot intensity is increased to improve signal detection, then measurement precision is improved, but material loss and damage increase
Solution Approach 1:
The light spot is applied in periodic scanning pulses rather than continuous high-intensity illumination. The scanning process uses brief, controlled light pulses at each measurement point, allowing the wafer to cool between measurements and reducing cumulative thermal damage while maintaining sufficient signal detection accuracy.
Solution Approach 2:
The system dynamically adjusts light spot parameters (intensity, duration, wavelength) based on the specific measurement requirements and wafer characteristics. By optimizing these parameters, the system achieves sufficient measurement precision with lower overall energy input, reducing the risk of wafer damage while maintaining detection accuracy.
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 enhances measurement accuracy and efficiency, enabling quantitative analysis and improving defect detection capabilities, thereby improving the quality inspection and yield in semiconductor manufacturing processes.
Implementation Method 1
Second harmonic is a nonlinear effect, which means that under certain conditions, a material can emit light with a frequency twice that of the incident light
Data Source
AI summary
A measuring method and device based on the second harmonic for the whole area measurement of a wafer comprises three modes: a fixed-point measurement, a scanning measurement, and a combination of the fixed-point measurement and the scanning measurement. The scanning measurement solution measures the entire wafer under the premise of ensuring high measurement efficiency, obtain the position, size and relative density distribution of electrical defects, and achieve locating and checking of abnormal points on the wafer. A new formula system is provided for describing the second harmonic signal, so that the actual measurement results and the theoretical model are unified under the three modes of the fixed-point measurement, the scanning measurement, and the combination of fixed-point measurement and scanning measurement, so that the second harmonic metrology technology is no longer only a qualitative analysis method, but also a quantitative analysis method.