SiC MOSFET Gate Insulator Nitrogen Segregation
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Solution Overview
Problem
Silicon carbide (SiC) semiconductor devices face a decrease in carrier mobility due to interface states between the SiC layer and the gate insulating layer, primarily caused by dangling bonds and stress-induced distortions in the gate insulating layer.
Innovation Solution
A semiconductor device with a silicon carbide layer and a silicon oxide gate insulating layer, where nitrogen is segregated at the interface to terminate dangling bonds and reduce distortion, using a silicon-rich silicon oxide film formed by low-temperature high-pressure nitrogen oxide treatment and subsequent high-temperature densification in a non-oxidizing atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gate insulating layer is formed on silicon carbide, then the device can be manufactured, but carrier mobility decreases due to interface states and distortion
Solution Approach 1:
The patent changes the physical and chemical parameters of the gate insulating layer by controlling oxygen partial pressure during formation to create a silicon-rich composition (SiO2-x where x>0). This parameter change reduces interface states and distortion, thereby improving carrier mobility in the SiC MOSFET.
Solution Approach 2:
The patent creates a composite structure at the interface between silicon carbide and silicon oxide by introducing a silicon-rich silicon oxide layer with non-stoichiometric composition. This composite material approach reduces the harmful interface states while maintaining the insulating function.
2Ease of manufacture
If the gate insulating layer is formed by conventional methods, then manufacturing is straightforward, but the layer exhibits high distortion and interface states
Solution Approach 1:
The patent modifies the formation process parameters by controlling oxygen partial pressure to be below the stoichiometric ratio, creating a silicon-rich silicon oxide layer. This parameter control achieves both manufacturability and high interface quality with reduced distortion.
Solution Approach 2:
The patent performs preliminary formation of a silicon-rich silicon oxide layer before final gate insulating layer completion. This preliminary action prepares the interface with reduced distortion and fewer interface states, improving the quality of the subsequent layers.
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 by reducing interface states and distortions, leading to improved performance of SiC MOSFETs by maintaining a high-density, low-distortion gate insulating layer.
Implementation Method 1
nitrogen is segregated at the interface to terminate dangling bonds
Implementation Method 2
subsequent high-temperature densification in a non-oxidizing atmosphere
Data Source
AI summary
A semiconductor device according to an embodiment includes a silicon carbide layer, a silicon oxide layer having a peak frequency of a longitudinal wave optical mode of 1245 cm−1 or more at a position 0.5 nm away from the silicon carbide layer, and a region located between the silicon carbide layer and the silicon oxide layer and having a nitrogen concentration of 1×1021 cm−3 or more. The concentration distribution of nitrogen in the silicon carbide layer, the silicon oxide layer, and the region has a peak in the region.