Automated XRR Location Selection for Semiconductor Wafer Inspection
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Solution Overview
Problem
Manual selection of XRR irradiation locations on semiconductor wafers is time-consuming, prone to human errors, and affected by surface features, leading to distorted X-ray spectra that do not accurately represent the layer properties.
Innovation Solution
An automated system that defines potential locations on the wafer surface, measures XRR spectra at each location, calculates a figure-of-merit (such as the overall length of the spectrum curve) to evaluate measurement quality, and selects the best locations for accurate data representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual selection of XRR irradiation locations is used, then measurement accuracy can be maintained by expert judgment, but the process is time-consuming and prone to human errors
Solution Approach 1:
The system enables automated selection of irradiation locations by having the measurement system itself evaluate and select optimal locations based on measured spectra quality, eliminating the need for manual expert judgment while maintaining measurement accuracy through objective criteria
Solution Approach 2:
The patent replaces the manual mechanical process of location selection with an automated computational system that uses algorithms to evaluate spectra quality metrics and automatically determine optimal irradiation locations, thereby reducing time loss while preserving measurement precision
2Quantity of substance
If irradiation area includes surface features like conductor patterns, then more signal is obtained, but the measured spectrum becomes distorted and does not represent true layer properties
Solution Approach 1:
The system performs preliminary evaluation of potential irradiation locations by measuring spectra at candidate positions and assessing their quality metrics before final selection, allowing identification and avoidance of locations where surface features would distort the measurement
Solution Approach 2:
The measurement system uses feedback from the measured spectra quality metrics to iteratively evaluate and select optimal irradiation locations, adjusting the selection based on whether the spectra accurately represent layer properties without distortion from surface features
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
Enables rapid, accurate selection of high-quality XRR spectra, reducing human error and improving the reliability of layer property estimation, particularly suitable for real-time applications in semiconductor fabrication.
Implementation Method 1
irradiating an area on the surface of a sample with a beam of X-rays at grazing incidence, i.e., at a small angle relative to the surface of the sample, near the total external reflection angle of the sample material
Implementation Method 2
Measurement of X-ray intensity reflected from the sample as a function of angle gives a profile of interference fringes, referred to as an XRR spectrum
Data Source
AI summary
The computer-implemented method for inspection of a sample includes defining a plurality of locations on a surface of the sample, irradiating the surface at each of the locations with a beam of X-rays, and measuring an angular distribution of the X-rays that are emitted from the surface responsively to the beam, so as to produce a respective plurality of X-ray spectra. The X-ray spectra are analyzed to produce respective figures-of-merit indicative of a measurement quality of the X-ray spectra at the respective location. One or more locations are selected out of the plurality of locations responsively to the figures-of-merit, and a property of the sample is estimated using the X-ray spectra measured at the selected location.