Semiconductor Buffer Layer With COi Defects for Thermal Stability
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Solution Overview
Problem
Conventional semiconductor devices do not account for variations in electric characteristics due to changes in crystal defects caused by heat, which can affect switching characteristics during actual use.
Innovation Solution
A semiconductor device with a drift layer, a first semiconductor layer, a first buffer layer with hydrogen-induced donors, and a second semiconductor layer, where the first buffer layer includes complex defects of interstice carbon and interstice oxygen with a density decreasing from the second principal plane toward the first principal plane, and a manufacturing method involving grinding, proton injection, heat treatment, and charged particle irradiation to form stable crystal defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crystal defects are formed by electron beam irradiation to improve donor generation rate by proton injection, then the donor generation rate is improved, but the electric characteristics vary due to heat-induced changes in crystal defects during actual use
Solution Approach 1:
The patent changes the type of crystal defects from conventional interstitial silicon or oxygen to a specific complex defect of interstitial carbon and interstitial oxygen (COi). This parameter change in defect composition results in defects that are more stable against heat-induced transformations, thereby maintaining stable electric characteristics during device operation while still providing the necessary donor generation rate improvement
Solution Approach 2:
The patent introduces a composite defect structure consisting of interstitial carbon and interstitial oxygen atoms combined in a specific configuration (COi complex). This composite defect structure exhibits superior thermal stability compared to simple interstitial defects, resolving the contradiction between achieving high donor generation rate and maintaining stable electric characteristics under heat
2Speed
If conventional crystal defects are used as lifetime killers to improve switching characteristic, then switching characteristic is improved, but variation in electric characteristics occurs due to heat-induced changes in crystal defects
Solution Approach 1:
The patent changes the fundamental parameter of crystal defect composition from conventional types (interstitial silicon, oxygen) to a carbon-oxygen complex (COi). This parameter change enables the defects to function effectively as lifetime killers for improving switching speed while simultaneously providing resistance against heat-induced transformations, thus maintaining electric characteristic stability
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
The semiconductor device achieves stable electrical characteristics by controlling the formation and density of crystal defects, ensuring consistent performance even under varying temperature conditions.
Implementation Method 1
protons are injected into the back surface side of a semiconductor substrate thinned by grinding to form a buffer layer having hydrogen-induced donors
Implementation Method 2
The semiconductor substrate is irradiated with charged particles such as electrons, protons, or helium to form crystal defects to be lifetime killers
Implementation Method 3
heat treatment is performed for one hour or more and ten hours or less at temperature of 350° C. or higher and 550° C. or lower and the injected protons are converted into the donors
Data Source
AI summary
A semiconductor device includes: a drift layer of a first conduction type provided in a semiconductor substrate having a first principal plane and a second principal plane opposed to the first principal plane; a first semiconductor layer of a second conduction type provided between the first principal plane of the semiconductor substrate and the drift layer and having impurity concentration higher than impurity concentration of the drift layer; a first buffer layer of a first conduction type provided between the second principal plane of the semiconductor substrate and the drift layer and having hydrogen-induced donors with impurity concentration higher than impurity concentration of the drift layer; and a second semiconductor layer of a first conduction type or a second conduction type provided between the second principal plane of the semiconductor substrate and the first buffer layer and having impurity concentration higher than impurity concentration of the drift layer, wherein the first buffer layer includes a complex defect of interstice carbon and interstice oxygen having density decreasing from the second principal plane side toward the first principal plane side.