Wafer Damage Depth Measurement via X-ray Rocking Curve Matching
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Solution Overview
Problem
Current methods for measuring the depth of mechanical damage in wafers are either destructive, time-consuming, or unable to provide accurate quantitative measurements, particularly for semiconductor wafers undergoing mechanical surface treatment processes.
Innovation Solution
A nondestructive method using X-ray diffraction to acquire and match rocking curves, calculate strain values, and model thickness based on X-ray diffraction beam intensity, allowing for precise determination of damage depth without damaging the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If etching or polishing method is used to measure damage depth, then measurement can be performed, but the method is destructive and takes a long time
Solution Approach 1:
The patent replaces the mechanical etching/polishing system with an X-ray diffraction-based measurement system. By using X-ray rocking curves and strain analysis, the method achieves damage depth measurement without mechanical contact or material removal, thereby eliminating the time-consuming polishing and heat-treatment steps while maintaining measurement capability.
Solution Approach 2:
The patent introduces X-ray diffraction as an intermediary measurement technique. Instead of directly measuring damage through destructive mechanical means, the method uses X-ray beams as a mediator to probe the wafer's crystalline structure and infer damage depth from strain analysis of rocking curves, enabling non-destructive measurement.
2Reliability
If X-ray diffractometer method is used, then measurement is nondestructive, but it can only determine damage qualitatively without quantitative depth information
Solution Approach 1:
The patent changes the measurement parameters by analyzing the Full Width at Half Maximum (FWHM) of X-ray rocking curves at different incident angles. By correlating FWHM variations with strain values and modeling the relationship between strain distribution and damage depth, the method transforms qualitative X-ray diffraction data into quantitative damage depth measurements while maintaining nondestructive measurement capabilities.
Solution Approach 2:
The patent implements a feedback mechanism by comparing measured rocking curves with simulated curves and iteratively adjusting the damage depth model. The measured FWHM values provide feedback to refine the strain distribution model, which in turn improves the accuracy of the calculated damage depth, enabling quantitative measurement from the nondestructive X-ray technique.
3Reliability
If Raman spectroscopy or photoluminescence method is used, then measurement is nondestructive, but it is impossible to measure the depth of damage
Solution Approach 1:
The patent replaces Raman spectroscopy or photoluminescence methods with X-ray diffraction-based strain analysis. While the alternative methods provide nondestructive measurement, they lack the capability to measure damage depth. The X-ray method substitutes these techniques by using strain values derived from rocking curve analysis to model and extract quantitative damage depth information that the other methods cannot provide.
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 accurate and efficient measurement of mechanical damage depth in wafers, surpassing the limitations of existing techniques by providing quantitative results without damaging the wafer, thus improving the precision and speed of wafer processing.
Implementation Method 1
acquiring a first rocking curve for a prepared wafer using an X-ray diffraction apparatus
Data Source
AI summary
The method of an embodiment includes the steps of: obtaining a first rocking curve with respect to a wafer obtained using an X-ray diffraction device; setting an X-ray incident angle range having a higher intensity than a reference level in the first rocking curve, calculating an inter-plane spacing for the set X-ray incident angle, calculating a strain value of the wafer using the calculated inter-plane spacing, and calculating sampled strain values on the basis of the calculated strain value; modeling a thickness according to the degree of damage of the wafer on the basis of the intensities of X-ray diffraction beams corresponding to the sampled strain values; obtaining a second rocking curve on the basis of the set X-ray incident angle range, the calculated inter-plane spacing, the sampled strain values and the modeled thickness; matching the second rocking curve to the first rocking curve by changing at least one of the X-ray incident angle range, the inter-plane spacing, the sampled strain values and the modeled thickness; and calculating the depth of damage of the wafer on the basis of the matching result.