SPV Measurement of Fe in P-Type Silicon Wafers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for measuring Fe concentration in p-type silicon wafers using the SPV method fail to simultaneously lower the detection limit and reduce measurement time, as changing from Standard Mode to Ultimate Mode does not effectively lower the detection limit for Fe concentration despite shorter measurement times.
Innovation Solution
Optimizing SPV measurement parameters such as Time Between Readings, Time Constant, and Number of Readings in both Standard and Ultimate Modes to achieve a lower detection limit for Fe concentration while shortening measurement time, specifically by setting Time Between Readings to 35 ms or more and 120 ms or less, or 10 ms or more and less than 35 ms, and Time Constant to 20 ms or more, and Number of Readings to 12 times or less in Ultimate Mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Standard Mode is used for SPV measurement, then measurement precision is maintained, but measurement time is excessive
Solution Approach 1:
The patent applies parameter changes by optimizing specific measurement parameters (Time Between Readings: 35-120 ms, Time Constant: 20 ms or more, Number of Readings: 12 times or less) in Ultimate Mode to achieve both reduced measurement time and maintained detection precision, resolving the contradiction between speed and accuracy
Solution Approach 2:
The patent employs dynamics by adaptively adjusting measurement parameters based on the detection requirements. The system dynamically selects optimal parameter combinations that balance measurement speed and precision, allowing the measurement system to adapt between different operational demands
2Loss of time
If Ultimate Mode is used for SPV measurement, then measurement time is shortened, but detection limit for Fe concentration increases
Solution Approach 1:
The patent resolves this contradiction by changing parameters within Ultimate Mode - specifically setting Time Between Readings to 35-120 ms (or 10-35 ms with adjusted Time Constant), Time Constant to 20 ms or more, and Number of Readings to 12 times or less. These parameter adjustments maintain detection precision while preserving the speed advantage of Ultimate Mode
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring measurement quality metrics and adjusting parameters accordingly. The system uses feedback from preliminary measurements to optimize subsequent measurement parameters, ensuring that detection precision requirements are met while minimizing measurement time
3Measurement precision
If Number of Readings is increased in Standard Mode, then detection limit for Fe concentration is lowered, but measurement time increases
Solution Approach 1:
The patent resolves this contradiction by changing the Number of Readings parameter to 12 times or less in Ultimate Mode, combined with optimized Time Between Readings and Time Constant settings. This parameter combination achieves the required detection precision while significantly reducing measurement time compared to traditional Standard Mode approaches
Solution Approach 2:
The patent applies continuity of useful action by performing multiple readings in rapid succession within Ultimate Mode rather than sequentially in Standard Mode. The optimized parameter settings allow continuous measurement activity without sacrificing precision, thereby improving productivity while maintaining detection capability
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
The optimized parameter settings allow for a lower detection limit and shorter measurement time for Fe concentration in p-type silicon wafers, improving production throughput and detection sensitivity.
Implementation Method 1
In the SPV method, a p-type silicon wafer is irradiated with lights having certain wavelengths, and the surface photovoltage (SPV signal) of the wafer at that time is measured, thereby determining the diffusion length of minority carriers in the wafer.
Data Source
AI summary
Provided is a method of measuring the Fe concentration in a p-type silicon wafer by the SPV method, by which the detection limit for the Fe concentration can be lowered, and the measurement can be performed in a short time. The measurement by the SPV method is performed in a measurement mode in which irradiation with a plurality of lights having mutually different wavelengths is performed during the same period under conditions where (i) Time Between Readings is 35 ms or more and 120 ms or less and Time Constant is 20 ms or more, or Time Between Readings is 10 ms or more and less than 35 ms and Time Constant is 100 ms or more, and (ii) Number of Readings is 12 times or less.