SiC MOSFET Interface Bonding for Mobility
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Solution Overview
Problem
Silicon carbide (SiC) MOSFETs face challenges with low carrier mobility and threshold voltage fluctuations due to interface states between the SiC layer and the gate insulating layer, primarily caused by carbon-carbon double bonds in the interface region.
Innovation Solution
The implementation of a silicon carbide semiconductor device with a silicon oxide layer and an interface region where the number of carbon-carbon single bonds is greater than carbon-carbon double bonds, achieved through controlled heat treatment with ozone or oxygen radicals, reducing interface state density and improving carrier mobility and threshold voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon carbide MOSFET is formed using conventional methods, then the device can be manufactured with standard processes, but the carrier mobility remains low due to interface states caused by carbon-carbon double bonds
Solution Approach 1:
The patent applies parameter changes by modifying the chemical bonding state in the interface region through controlled heat treatment. By adjusting temperature parameters during heat treatment, carbon-carbon double bonds are converted to single bonds, thereby reducing interface state density and improving carrier mobility without fundamentally changing the manufacturing process flow
Solution Approach 2:
The patent uses ozone or oxygen radicals as strong oxidizing agents during heat treatment to facilitate the conversion of carbon-carbon double bonds to single bonds in the SiC interface region. This accelerated oxidation process effectively reduces interface states and improves device performance
2Stability of the object's composition
If the silicon carbide interface is formed with conventional processing, then the manufacturing is simple, but the threshold voltage fluctuates due to interface states
Solution Approach 1:
The patent applies preliminary action by performing heat treatment with ozone or oxygen radicals before final device assembly and operation. This pre-treatment converts carbon-carbon double bonds to single bonds in advance, establishing a stable interface structure that prevents subsequent threshold voltage fluctuations
Solution Approach 2:
Ozone or oxygen radicals are used as strong oxidants to promote the conversion of carbon-carbon double bonds to single bonds in the SiC interface region. This oxidation process reduces interface state density and stabilizes the threshold voltage
3Reliability
If carbon-carbon double bonds are present in the interface region, then the interface forms naturally during oxidation, but carrier mobility decreases due to increased interface state density
Solution Approach 1:
The patent changes the chemical bonding parameters in the interface region by controlling heat treatment conditions. This converts carbon-carbon double bonds to single bonds, thereby reducing interface state density and improving carrier mobility
Solution Approach 2:
Strong oxidants (ozone or oxygen radicals) are used to facilitate the conversion of carbon-carbon double bonds to single bonds, reducing the quantity of double bonds and associated interface states in the interface region
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 enhances carrier mobility and stabilizes the threshold voltage by converting carbon-carbon double bonds to single bonds in the interface region, resulting in improved MOSFET performance.
Implementation Method 1
performing first heat treatment at a partial pressure of ozone of 10% or less or a partial pressure of oxygen radical of 10% or less, and a temperature of 400° C. or less
Data Source
AI summary
A semiconductor device according to an embodiment includes a silicon carbide layer having a front surface inclined at 0° or more and 10° or less with respect to a (0001) face, a silicon oxide layer, and a region located between the front surface and the silicon oxide layer and having the number of carbon-carbon single bonds larger than the number of carbon-carbon double bonds.