SiC Semiconductor Gate Electrode Work Function Engineering
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Solution Overview
Problem
In semiconductor devices using silicon carbide (SiC), there is a challenge in adjusting the threshold value of gate voltage without deteriorating current and voltage properties, particularly in improving electron transfer in the inversion layer and the reliability of the gate insulating film.
Innovation Solution
A semiconductor device configuration with a first semiconductor region, a second semiconductor region, and a control electrode is implemented, where the control electrode has regions with different effective work functions, and an insulating film is used to adjust the gate voltage threshold without compromising current and voltage properties, utilizing materials like silicon dioxide with nitrogen and specific metal nitrides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon dioxide gate insulating film is used in a silicon carbide semiconductor device, then the breakdown electric field intensity and thermal conductivity are improved, but the electron transfer degree of the inversion layer deteriorates
Solution Approach 1:
The patent applies parameter changes by introducing nitrogen into the silicon dioxide gate insulating film at controlled concentrations (1×10^19 to 1×10^21 atoms/cm³). This chemical parameter modification enables the film to achieve both high breakdown electric field intensity and improved electron transfer degree in the inversion layer, resolving the contradiction between reliability and manufacturing precision
Solution Approach 2:
The patent creates a composite gate insulating film by combining silicon dioxide with nitrogen atoms. This composite structure maintains the excellent breakdown characteristics of SiO2 while the incorporated nitrogen enhances the electron transfer properties, simultaneously achieving both improved reliability and electron transfer degree
2Reliability
If the gate insulating film is optimized for high breakdown field, then the reliability is improved, but the threshold value adjustment capability deteriorates
Solution Approach 1:
By precisely controlling the nitrogen concentration parameter within the range of 1×10^19 to 1×10^21 atoms/cm³, the patent achieves optimal balance between breakdown field strength and threshold voltage adjustability. This parameter optimization allows the gate insulating film to maintain high reliability while enabling effective threshold value adjustment for different device requirements
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first semiconductor region, a second semiconductor region, a third semiconductor region, an insulating film, and a control electrode. The first semiconductor region includes a silicon carbide of a first conductivity type. The second semiconductor region is provided on the first semiconductor region, includes a silicon carbide of a second conductivity type, and has a first main surface. The third semiconductor region is provided on the second semiconductor region and includes the silicon carbide of the first conductivity type. The film is provided on the surface. The electrode is provided on the film, and has a first region close to the third semiconductor region side, and a second region closer to the first semiconductor region side than the first region. An effective work function of the first region is larger than an effective work function of the second region.