Wafer Metal Impurity Detection Using Two-Stage Thermal Diffusion
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Solution Overview
Problem
Current methods for detecting metal impurities in semiconductor wafers are time-consuming and inefficient, affecting the quality and yield of semiconductor devices due to the difficulty in diffusing and detecting impurities like copper and nickel effectively.
Innovation Solution
A method involving a combination of medium temperature thermal treatment (350° C.-550° C.) and low temperature thermal treatment (200° C.-300° C.) followed by vapor phase decomposition and inductively coupled plasma mass spectrometry analysis to efficiently diffuse and detect metal impurities on the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional single-temperature thermal treatment is used, then the detection process is simple, but the diffusion efficiency of metal impurities to the wafer surface is low and detection time is long
Solution Approach 1:
The thermal treatment process is segmented into two distinct temperature stages: a first thermal treatment at a first temperature and a second thermal treatment at a second temperature. This segmentation allows different metal impurities to diffuse to the wafer surface at their respective optimal temperatures, thereby improving overall detection efficiency without requiring a single complex high-temperature process
Solution Approach 2:
The process utilizes parameter changes by varying the temperature parameter between two distinct levels. The first thermal treatment uses a first temperature optimized for certain metal impurities, while the second thermal treatment uses a second temperature optimized for other metal impurities. This parameter variation enables efficient diffusion of diverse metal impurities to the surface for detection
2Speed
If high temperature thermal treatment is used to diffuse metal impurities, then diffusion speed increases, but wafer damage and deformation risk increases
Solution Approach 1:
Instead of using a single high temperature that risks wafer damage, the process changes the temperature parameter to use two moderate temperatures. The first thermal treatment uses a first temperature that is sufficient for certain metal impurities to diffuse, and the second thermal treatment uses a second temperature for other impurities. This parameter optimization achieves effective diffusion while avoiding wafer damage
Solution Approach 2:
The diffusion process is segmented into two separate thermal treatments at different temperatures rather than one high-temperature treatment. This segmentation allows each metal impurity type to diffuse at its optimal temperature, achieving high diffusion speed for each type without subjecting the wafer to damaging high temperatures
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 reduces time costs and enhances detection efficiency by effectively diffusing and quantifying metal impurities such as copper and nickel, improving the quality control of semiconductor wafers.
Implementation Method 1
the nickel diffuses to the wafer surface during the medium temperature thermal treatment
Implementation Method 2
the copper diffuses to the wafer surface during the low temperature thermal treatment
Implementation Method 3
providing a liquid of vapor phase decomposition on the wafer surface to collect metal impurities therefrom
Implementation Method 4
conducting an inductively coupled plasma mass spectrometry analysis
Data Source
AI summary
The present application provides a detection method of metal impurity in wafer. The method comprises conducting a medium temperature thermal treatment for a first predicted time period to the wafer, cooling the wafer and conducting a low temperature thermal treatment for a second predicted time period, cooling the wafer to ambient temperature; providing a liquid of vapor phase decomposition on the wafer to collect metal impurities; atomizing the liquid containing the collected metal impurities, conducting an inductively coupled plasma mass spectrometry analysis and obtaining concentrations of the metal impurities. The present application applies the combination of various thermal treatment without an interrupt of cooling to ambient temperature to contemplate diffusions of various metal impurities to the wafer surface. Accordingly, the detection of metal impurities can be conducted with reduced time cost and enhanced efficiency.