SiC Semiconductor Drift Layer Defect Management
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Solution Overview
Problem
The development of semiconductor devices for power electronics is hindered by defects in large-area semiconductor chips, which reduce yield and lead to leakage currents due to micropipes and epitaxial defects, especially in silicon carbide substrates, where traditional methods like covering micropipes with insulation layers can still result in breakdowns under high voltage.
Innovation Solution
A semiconductor device design that includes a drift layer with a thickness t, a first electrode making an ohmic or Schottky contact on the surface except in a depletion control region, and a second electrode with an ohmic contact on the substrate's rear surface, where the depletion control region is circular or sector-shaped with a radius not less than t, preventing the depletion layer from extending to defects and thus reducing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large-area semiconductor chips are used for power electronics applications, then the current handling capability is improved, but the likelihood of containing defects increases, which reduces yield
Solution Approach 1:
The invention converts the harmful effect of defects into a beneficial outcome by intentionally creating a depletion control region around defect locations. This region prevents the depletion layer from extending to defects under reverse bias, thereby eliminating leakage currents caused by defects while maintaining the large chip area needed for high current handling capability
Solution Approach 2:
The invention applies a localized solution by creating a depletion control region only around specific defect locations rather than modifying the entire chip structure. This allows the majority of the large-area chip to maintain its optimal electrical characteristics while locally addressing the leakage problem at defect sites
2Reliability
If traditional insulation layer methods are used to cover micropipes, then the defect coverage is achieved, but breakdowns still occur under high voltage due to leakage currents
Solution Approach 1:
Instead of merely covering defects with insulation layers which fails to prevent leakage, the invention utilizes the electrical field effects to create a depletion control region that actively prevents the depletion layer from reaching defects. This converts the previously harmful leakage current path into a controlled region where no leakage occurs
Solution Approach 2:
The invention changes the electrical parameters in the region around defects by creating a depletion control region with specific doping characteristics. This alters the electric field distribution to prevent depletion layer extension to defect sites, thereby eliminating leakage currents without physical coverage
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 design effectively prevents the generation of leakage currents even with defects present, enhancing the yield of semiconductor devices by ensuring that defects are not depleted under reverse bias, thereby meeting product specifications.
Implementation Method 1
the depletion control region includes a circular or sector-shaped region having a radius of not less than t... preventing the depletion layer from extending to defects
Implementation Method 2
The first electrode is in a region, on a surface of the drift layer, except a depletion control region and has an ohmic contact or a Schottky contact with the drift layer
Implementation Method 3
The first electrode is in a region, on a surface of the drift layer, except a depletion control region and has an ohmic contact or a Schottky contact with the drift layer
Data Source
AI summary
Semiconductor device includes semiconductor substrate, drift layer, first electrode, and second electrode. Semiconductor substrate is of a first conductivity type and is formed of a silicon carbide semiconductor, a gallium nitride semiconductor, or the like. For example, semiconductor substrate is an n-type silicon carbide semiconductor substrate. Drift layer is an epitaxial semiconductor layer of the first conductivity type which is formed on upper surface of semiconductor substrate by epitaxial growth. Drift layer is formed of, for example, an n-type silicon carbide semiconductor. Drift layer has a thickness of t. For example, the thickness t is between about 5 μm and about 100 μm (inclusive).