Wafer Metal Contamination Analysis With ICP-MS Interference Correction
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Solution Overview
Problem
Inductively-coupled plasma-mass spectrometry (ICP-MS) for wafer contamination analysis faces interference issues between metals with similar masses, leading to inaccurate contamination level measurements and reduced reliability.
Innovation Solution
A method and apparatus using a correlation equation to correct contamination levels by accounting for interference between metals like Ni and Fe, employing a controller to obtain and apply correction values based on verified samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ICP-MS is used for contamination analysis, then metal contamination levels can be detected, but interference phenomenon occurs between elements of similar mass causing distorted measurements
Solution Approach 1:
The patent introduces a correlation equation as an intermediary computational model that relates the contamination levels of interfering metals (e.g., Fe-56 and Ni-58). By substituting the measured contamination level of one metal into the correlation equation, a correction value is obtained that accounts for the interference effect, thereby mediating between the raw measurement and the true contamination level.
Solution Approach 2:
The patent changes the parameter representation by introducing a correction value derived from correlation equations. Instead of directly using the raw contamination level measurement, the method transforms the measurement by applying a correction factor (y = 0.143x + 0.055) that adjusts the measured value to compensate for interference effects, thus changing the parameter from raw measurement to corrected contamination level.
2Measurement precision
If correction values are calculated using correlation equations, then measurement accuracy is improved, but additional calculation steps and data processing are required
Solution Approach 1:
The patent applies preliminary action by pre-establishing correlation equations based on interference relationships between metals before actual contamination analysis. The correlation equations (e.g., y = 0.143x + 0.055 for Fe-56 and Ni-58) are determined in advance through verification using mixed solutions, so that during actual measurement, only simple substitution and calculation are needed rather than complex real-time analysis.
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
Accurately determines metal contamination levels by correcting for interference, enhancing reliability and precision in wafer analysis.
Implementation Method 1
The various metals on the wafer are separated by mass by the mass separator of ICP-MS
Implementation Method 2
An inductively-coupled plasma-mass spectrometry (hereinafter referred to as ICP-MS) is used for contamination analysis
Data Source
AI summary
A method for analyzing metal contamination of a wafer comprises obtaining a contamination level of a first metal and a contamination level of a second metal for the wafer, obtaining a correction value by substituting the obtained contamination level of the second metal into a correlation equation, and obtaining a final contamination level of the first metal, by correcting the contamination level of the obtained first metal based on the correction value.