Semiconductor Buffer Layer Defect Profile for Stable Switching
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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 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 switching characteristics are improved, but variation in electric characteristics occurs due to heat-induced changes in crystal defects during actual use
Solution Approach 1:
The patent changes the type of crystal defects from conventional single-type defects to a specific combination of interstice carbon and interstice oxygen complex defects. This parameter change in defect composition makes the defects resistant to thermal degradation, thereby maintaining stable electric characteristics during actual use while preserving improved switching characteristics.
Solution Approach 2:
The patent creates a composite defect structure by combining interstice carbon and interstice oxygen to form complex defects. This composite defect structure exhibits enhanced thermal stability compared to conventional single-type crystal defects, preventing variation in electric characteristics under thermal stress while maintaining the desired switching performance.
2Reliability
If conventional heat treatment is performed to activate protons and form buffer layer, then hydrogen-induced donors are formed, but crystal defects used as lifetime killers undergo heat-induced changes causing electric characteristic variation
Solution Approach 1:
The patent performs preliminary formation of stable interstice carbon and interstice oxygen complex defects before the heat treatment that activates protons. This preliminary action ensures that when heat treatment is applied to form the buffer layer with hydrogen-induced donors, the crystal defects remain stable and do not undergo detrimental heat-induced changes, thus maintaining both donor generation rate and defect stability.
3Speed
If electron beam irradiation is used to form crystal defects, then lifetime killers are created to improve switching characteristic, but the same defects cause variation in electric characteristics under thermal stress
Solution Approach 1:
The patent changes the fundamental parameter of defect composition from conventional electron-beam-induced defects to specifically formed interstice carbon and interstice oxygen complex defects. This parameter change enables the defects to serve as effective lifetime killers that maintain stable composition under thermal stress, thereby achieving both improved switching speed and stable electric characteristics.
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
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
Implementation Method 3
The semiconductor substrate is irradiated with charged particles such as electrons, protons, or helium to form crystal defects to be lifetime killers, which reduce a recombination life time of a carrier
Implementation Method 4
heat treatment is performed for one hour or more and ten hours or less at temperature of 300° C. or higher and 500° C. or lower and an amount of the crystal defects is adjusted
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.