Wafer Resistivity Measurement with Oxidized Surface Stabilization
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Solution Overview
Problem
Current methods for measuring the resistivity of high-resistivity monocrystalline silicon wafers are prone to time variation, leading to long stabilization times and inaccurate measurements.
Innovation Solution
A measuring method that involves thermal treatment to remove thermal donors, followed by an oxidation process to form a stable oxidized surface, and finally using a collinear four-point probe method to measure the resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a four-point probe method is used to measure high-resistivity wafers, then measurement can be performed, but the measurement results show time variation requiring long stabilization periods
Solution Approach 1:
The patent applies preliminary action by performing thermal treatment and oxidation processes before the resistivity measurement. The thermal treatment at 750-1250°C for 30-50 seconds removes thermal donors, and the subsequent oxidation forms a stable oxidized surface layer. These preparatory steps eliminate the time variation problem during measurement, allowing stable readings to be obtained quickly without long stabilization periods.
Solution Approach 2:
The patent changes the physical and chemical parameters of the wafer surface through thermal treatment and oxidation. By heating the wafer to high temperatures and then exposing it to oxidation, the surface properties are fundamentally altered to create a stable oxidized layer. This parameter change approach transforms the unstable measurement condition into a stable one, resolving the time variation issue.
2Measurement precision
If high-resistivity wafers are measured without preliminary thermal treatment, then measurement can be performed quickly, but the results show significant time variation and instability
Solution Approach 1:
The patent performs thermal treatment and oxidation as preliminary actions before measurement. The thermal treatment at 750-1250°C for 30-50 seconds removes thermal donors, and the oxidation process creates a stable surface. This preliminary preparation eliminates time variation, enabling both high measurement precision and fast stabilization, thus resolving the contradiction between accuracy and speed.
3Measurement precision
If thermal treatment is applied to remove thermal donors, then measurement stability is improved, but additional process time is required
Solution Approach 1:
The patent uses parameter changes by optimizing the thermal treatment conditions (temperature range of 750-1250°C and duration of 30-50 seconds) to achieve effective removal of thermal donors. The subsequent oxidation process is performed at relatively low temperatures (50-300°C) for short durations (5 minutes to 3 hours). These optimized parameters achieve measurement stability while minimizing total process time.
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 significantly reduces the time required to stabilize resistivity measurements and allows for precise and fast measurement of high-resistivity wafers, overcoming the limitations of existing technologies.
Implementation Method 1
conducting a thermal treatment for the wafer to remove a thermal doner in the wafer
Implementation Method 2
conducting an oxidation process for the wafer to form an oxidized surface on the wafer
Data Source
AI summary
The invention provides a measuring method of resistivity of a wafer, comprising: choosing a wafer to be measured, conducting a thermal treatment for the wafer to remove a thermal doner in the wafer, conducting an oxidation process for the wafer to form an oxidized surface on the wafer, and measuring resistivity of the wafer. In the method, firstly, the wafer is oxidized to get the oxidized surface, so as to restrict surface variation when placing the wafer in a later process. Therefore, the resistivity measurement of the wafer surface only slightly varies.