SiC Device Protruding Gate Electrode Solder Flow
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Solution Overview
Problem
Conventional silicon carbide semiconductor devices face reliability issues due to decreased adhesion between electrodes at high temperatures, leading to solder displacement and potential short circuits when subjected to thermal stress, especially with the use of aluminum electrodes that do not act as barriers against solder diffusion.
Innovation Solution
The design incorporates a gate electrode with protruding portions extending orthogonally to the striped shape of the contact holes, which prevents solder from flowing along grooves on the source electrode pad, distributing the solder flow and reducing the pushing force, thereby preventing it from entering the device and causing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aluminum electrodes are used without barrier layers, then manufacturing simplicity is improved, but solder diffusion and adhesion failure occur at high temperatures
Solution Approach 1:
A barrier layer is introduced as an intermediary between the aluminum electrode and the solder. This barrier layer prevents direct contact and diffusion between the aluminum and solder, eliminating the adhesion failure issue while maintaining the simplicity of using aluminum electrodes without requiring complex multi-layer electrode structures
Solution Approach 2:
The barrier layer is designed as a thin, simple layer that provides its protective function and can be integrated into the existing manufacturing process without adding significant complexity or cost. It acts as a sacrificial or permanent barrier that fulfills its purpose of preventing solder diffusion
2Reliability
If conventional trench gate structure is used, then device performance is improved, but solder flows along grooves and causes short circuits at high temperatures
Solution Approach 1:
The protruding portion of the gate electrode is designed in advance to counteract the harmful effect of solder flow. By extending into the bridge area, it creates a physical barrier that prevents solder from flowing along the grooves before the soldering process occurs, thereby preventing short circuits
Solution Approach 2:
The gate electrode structure is extended into a third dimension by adding the protruding portion that bridges between trenches. This dimensional extension creates a new spatial barrier that blocks the two-dimensional flow path of solder along the grooves, preventing solder from reaching critical areas
Data Source
AI summary
A silicon carbide semiconductor device includes a first semiconductor layer of a first conductivity type on a substrate of the first conductivity type, a second semiconductor layer of a second conductivity type on the first semiconductor layer, and a first semiconductor region of the first conductivity type. The semiconductor device further includes a gate electrode provided in a plurality of trenches via gate insulating films, a protruding portion disposed on the second semiconductor layer at a bridge area between two adjacent ones of the trenches in a direction orthogonal to the trenches, an interlayer insulating film provided on the gate electrode, and having contact holes that form a striped pattern, a first electrode on the interlayer insulating film and in the contact holes, a plating film provided in a plating area, and a solder on the plating film.