Infrared Depolarization for Silicon Substrate Slip Resistance
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Solution Overview
Problem
Conventional methods for determining slip resistance of silicon substrates during epitaxy and post-epitaxy thermal treatment are destructive and unable to evaluate different epitaxial substrates under various treatments.
Innovation Solution
A method involving the Czochralski growth process, where silicon substrates are grown with varying impurity profiles, and their suitability for epitaxy is determined by imaging with infrared depolarization to obtain infrared depolarization parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional destructive methods are used to detect slip resistance, then measurement capability is achieved, but the wafer is destroyed and cannot be used further
Solution Approach 1:
The patent replaces destructive mechanical stress testing with non-destructive infrared depolarization imaging. The infrared imaging system detects internal stress and dislocation structures in the wafer without physical contact or damage, allowing the wafer to remain usable after measurement.
Solution Approach 2:
The patent introduces infrared radiation as an intermediary to probe the wafer's internal structure. The infrared imaging system acts as a mediator that translates internal stress states into observable depolarization patterns without directly interacting with or damaging the wafer material.
2Loss of information
If conventional processes are used, then single evaluation point is obtained, but inability to evaluate different substrates under different treatments limits optimization
Solution Approach 1:
The patent segments the wafer into multiple evaluation regions through infrared imaging, capturing depolarization data across the entire wafer surface rather than at a single point. This enables comprehensive evaluation of different substrate regions and their response to various epitaxial and thermal treatments.
Solution Approach 2:
The infrared depolarization imaging system serves multiple evaluation functions simultaneously, assessing slip resistance, internal stress, and substrate quality across different treatment conditions, replacing multiple separate measurement processes with a single versatile technique.
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 allows for non-destructive, quantitative evaluation of slip resistance and suitability of silicon substrates for epitaxy under different conditions, enabling the determination of optimal growth conditions.
Implementation Method 1
A front surface of a silicon substrate is contacted with a silicon-containing gas. The silicon-containing gas decomposes to form an epitaxial silicon layer on the silicon substrate
Implementation Method 2
The first epitaxial wafer is imaged by infrared depolarization to determine a first infrared depolarization parameter
Data Source
AI summary
Methods for determining suitability of Czochralski growth conditions to produce silicon substrates for epitaxy. The methods involve evaluating substrates sliced from ingots grown under different growth conditions (e.g., impurity profiles) by imaging the wafer by infrared depolarization. An infrared depolarization parameter is generated for each epitaxial wafer. The parameters may be compared to determine which growth conditions are well-suited to produce substrates for epitaxial and/or post-epi heat treatments.