SiC MISFET Leakage Current Reduction via Nitrogen-Rich Interface
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
SiC-based MISFETs face increased leakage current through the gate insulating film due to the C face channel, which is not present in Si face channels, leading to higher ON resistance and reduced mobility.
Innovation Solution
A semiconductor device with a SiC layer having a surface region with a nitrogen concentration higher than 1×1022 cm−3 and a p-type impurity concentration less than 5×1015 cm−3, combined with a nitrogen-rich interface region, is used to reduce leakage current by minimizing the potential barrier between the SiC layer and the gate insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a C face channel is used in SiC-based MISFET, then carrier mobility is improved, but leakage current through the gate insulating film increases
Solution Approach 1:
The patent applies local quality by creating a surface region with specifically controlled impurity concentrations (nitrogen concentration higher than 1×10^22 cm^-3 and p-type impurity concentration less than 5×10^15 cm^-3) at the interface between the SiC layer and gate insulating film. This localized modification of the surface region's electrical properties reduces leakage current through the gate insulating film while preserving the high mobility characteristics of the C face channel in the bulk material.
2Object-generated harmful factors
If nitrogen concentration is increased at the SiC layer surface, then leakage current is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent employs parameter changes by precisely controlling the nitrogen concentration to be higher than 1×10^22 cm^-3 and p-type impurity concentration to be less than 5×10^15 cm^-3 in the surface region. These specific parameter thresholds transform the SiC surface properties to reduce leakage current while providing clear manufacturing specifications that guide the fabrication process.
Data Source
AI summary
A semiconductor device according to an embodiment includes a SiC layer including a first region provided at a surface. The first region satisfies NA−ND<5×1015 cm−3 when a concentration of a p-type impurity is denoted by NA, whereas a concentration of an n-type impurity is denoted by ND. The surface is inclined at 0 degrees or more and 10 degrees or less to a {000-1} face, or the surface having a normal direction inclined at 80 degrees or more and 90 degrees or less to a <000-1> direction. The device includes a gate electrode, a gate insulating film provided between the SiC layer and the gate electrode, and a second region provided between the first region and the gate insulating film. The second region has a nitrogen concentration higher than 1×1022 cm−3.