Power Semiconductor Electrode Hardness Control
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Solution Overview
Problem
Conventional vertical power semiconductor devices experience element breakage during wire connection through ultrasonic bonding or pressure welding/soldering due to deformation of metal films, which are not adequately prevented by existing high-strength metal films with low hardness.
Innovation Solution
A power semiconductor device configuration featuring a first main electrode with a barrier metal film, a high-hardness intermediate film, and a second metal film, where the intermediate film is made of metal compounds with primary-constituent phases and a secondary-constituent phase of an iron group element, enhancing the hardness and reliability by preventing deformation during connection processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-strength metal film with low hardness is used in the emitter electrode, then the deformation in the second metal film is reduced during wire connection, but the high-strength metal film itself deforms and fails to sufficiently prevent element breakage
Solution Approach 1:
The patent changes the hardness parameter of the metal film by introducing a specific compositional structure: a high-strength metal film containing 95-99.99 wt% Al with controlled impurity content (Fe: 0.003-0.03 wt%, Si: 0.003-0.03 wt%). This parameter optimization achieves both high strength and sufficient hardness to prevent element breakage during wire connection and pressure welding/soldering processes.
Solution Approach 2:
The patent creates a composite metal film structure by carefully controlling the composition of the high-strength metal film, combining Al as the base metal with specific amounts of Fe and Si impurities. This composite composition provides both the required strength and hardness properties that pure Al or previously used materials could not achieve simultaneously.
2Device complexity
If conventional metal films are used in the emitter electrode, then the device structure is simple, but element breakage occurs during wire connection through ultrasonic bonding or pressure welding/soldering
Solution Approach 1:
The patent optimizes the compositional parameters of the metal film (Al content: 95-99.99 wt%, Fe: 0.003-0.03 wt%, Si: 0.003-0.03 wt%) to achieve the right balance between mechanical properties and structural simplicity, avoiding complex multi-layer structures while preventing element breakage.
Data Source
AI summary
Provided is a power semiconductor device that prevents element breakage, thus improving its reliability. The power semiconductor device includes a first main electrode. The first main electrode includes a first metal film, an intermediate film, and a second metal film. The first and second metal films are made of metal having an Al concentration greater than or equal to 95 wt %. The intermediate film contains primary-constituent phases each formed of a metal compound, and contains a secondary-constituent phase formed of an iron group element. The metal compound is that of at least one kind of element selected from a group consisting of a group 4A element, a group 5A element, and a group 6A element, and at least one kind of element selected from a group consisting of C and N. The intermediate film has a higher degree of hardness than the second metal film.