Trench-Gate SiC Source Structure for Low-Leak Ohmic Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Trench-gate SiC semiconductor devices with 3C—SiC in the source region suffer from high crystal defects, leading to a roughened surface and increased leak current between the gate electrode and the source region due to ohmic contact issues.
Innovation Solution
The design includes a trench-gate SiC semiconductor device configuration where the source region has a 4H—SiC source expansion part in contact with the gate insulating film and a 3C—SiC source contact part separated from the gate insulating film, allowing for ohmic contact with the source electrode while minimizing leak current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 3C-SiC is used in the source region to achieve ohmic contact with the source electrode, then electrical contact resistance is reduced, but crystal defects increase and surface roughening occurs leading to increased leak current
Solution Approach 1:
The source region is divided into two distinct parts: a 4H-SiC source expansion part that contacts the gate insulating film and a 3C-SiC source contact part that contacts the source electrode. This segmentation allows each part to perform its specific function optimally while avoiding the harmful interaction between 3C-SiC and the gate insulating film, thereby suppressing leak current while maintaining ohmic contact.
Solution Approach 2:
Different crystal structures are assigned to different locations within the source region based on their specific functional requirements. The 4H-SiC structure is used where contact with the gate insulating film is needed (to prevent leak current), while the 3C-SiC structure is used where contact with the source electrode is needed (to achieve low resistance ohmic contact). This local differentiation of material properties resolves the contradiction between leak current suppression and ohmic contact formation.
Data Source
AI summary
A silicon carbide semiconductor device includes: a drift layer of a first conductivity-type including silicon carbide; a base region of a second conductivity-type provided on a top surface side of the drift layer; a main region of the first conductivity-type provided on a top surface side of the base region; a gate electrode buried inside a trench with a gate insulating film interposed; and a main electrode provided in contact with the main region, wherein the main region includes a first region with a bottom surface in contact with the base region, and a second region including a 3C structure and provided at an upper part of the first region separately from the gate insulating film inside the trench so as to be in contact with the main electrode.