SiC Device Passivation Structure for Source Pad Migration
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Solution Overview
Problem
Conventional silicon carbide semiconductor devices experience migration at the source pad due to increased heat generation during high current flow and short-circuit operations, which affects device reliability.
Innovation Solution
The silicon carbide semiconductor device incorporates a specific passivation film structure with interlayer insulations and plating films to prevent solder from reaching the gate pad, allowing for efficient heat dissipation and reducing source pad migration. This structure includes a first passivation film with a first interlayer insulation between the gate and source pads, and a second passivation film covering the plating films, ensuring that the edges of the openings expose the pads in a manner that prevents solder from bridging between them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is provided on the source pad to connect metal plate, then electrical connection is achieved, but solder may reach the gate pad causing short circuit
Solution Approach 1:
The passivation film is divided into multiple regions with different properties: a first passivation film covering the gate pad area and a second passivation film covering the source pad area, allowing each region to serve its specific function while preventing solder migration to the gate pad
Solution Approach 2:
Different passivation films are applied to different locations: the first passivation film has properties suitable for gate pad protection, while the second passivation film has properties optimized for source pad solder resistance, creating location-specific protection strategies
2Reliability
If passivation film is provided to prevent solder from reaching gate pad, then short circuit is prevented, but heat dissipation may be affected
Solution Approach 1:
The passivation structure is segmented into multiple films with different thicknesses and material properties, allowing the first passivation film to provide electrical isolation while the second passivation film maintains thermal conduction pathways for effective heat dissipation
Solution Approach 2:
The multi-layer passivation structure uses composite materials with different electrical and thermal properties, combining materials that provide both electrical isolation and thermal management capabilities
3Ease of manufacture
If conventional single passivation film structure is used, then manufacturing is simple, but source pad migration occurs due to heat generation
Solution Approach 1:
The passivation system is segmented into multiple films formed through sequential processes, where each film is deposited and patterned separately, enabling precise control over the structure while maintaining manufacturability through standard semiconductor fabrication techniques
Solution Approach 2:
The first passivation film is formed preliminarily to establish the basic protection structure, followed by the formation of the second passivation film to enhance source pad stability, allowing each layer to be optimized independently
Data Source
AI summary
A silicon carbide semiconductor device includes a first passivation film formed on gate and source pads on a principal surface of a silicon carbide substrate, and a second passivation film formed on the first passivation film. The first passivation film includes a first interlayer insulation between the gate and source pads, a first opening exposing the gate pad and having a first edge, and a second opening exposing the source pad and having a second edge. First and second plating film are formed on the gate and source pads inside the first and second openings, respectively. The second passivation film is also formed on the first and second plating films, and includes a second interlayer insulation covering the first interlayer insulation, a third opening exposing the first plating film and having a third edge, and a fourth opening exposing the second plating film and having a fourth edge.