Nitrogen Profile Control in Silicon Semiconductor Devices
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Solution Overview
Problem
Semiconductor devices, particularly power semiconductor devices, face challenges with crystal originated particles (COPs) that lead to enhanced leakage current and weakened gate dielectrics, due to high nitrogen concentrations during crystal growth, which can be exacerbated by proton implantation affecting n-type doping regions.
Innovation Solution
A method involving a silicon wafer with an initial high nitrogen concentration, followed by partial out-diffusion of nitrogen to reduce the concentration near the surface to below 2*10^14 cm^-3, specifically in the first 50 μm depth, to minimize COPs and maintain effective n-type doping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the speed of crystal growth is reduced to reduce COPs, then the concentration and size of crystal originated particles decrease, but manufacturing costs increase
Solution Approach 1:
The patent changes the parameter of nitrogen concentration during crystal growth to achieve COP suppression without requiring reduced growth speeds. By controlling nitrogen incorporation to specific concentration ranges and depth profiles, the method achieves reliable device performance while maintaining standard crystal growth rates, thereby avoiding increased manufacturing costs.
2Reliability
If nitrogen concentration is high in the silicon layer, then COPs are suppressed, but n-type doping regions formed by proton implantation are partially compensated, reducing device performance
Solution Approach 1:
The patent applies local quality by creating a depth-dependent nitrogen concentration profile where the nitrogen concentration is high at deeper regions (suppressing COPs) and low at surface regions (avoiding doping compensation). This is achieved through controlled nitrogen incorporation during crystal growth followed by selective removal processes that maintain the gradient, ensuring each depth region has the appropriate nitrogen level for its specific function.
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 the detrimental effects of nitrogen on n-type doping, decreases the concentration and size of COPs, thereby enhancing the performance and reliability of semiconductor devices by minimizing leakage current and maintaining charge carrier lifetime.
Implementation Method 1
partially out-diffusing nitrogen to reduce the nitrogen concentration of the silicon layer at least close to the main surface
Data Source
AI summary
A semiconductor device includes a silicon semiconductor body having a main surface and a nitrogen concentration which is lower than about 2*1014 cm−3 at least in a first portion of the silicon semiconductor body, the first portion extending from the main surface to a depth of about 50 μm. The nitrogen concentration increases with a distance from the main surface at least in the first portion. The semiconductor device further includes a field-effect structure arranged next to the main surface.