Diffusion-Soldered Power Semiconductor Assembly With Contaminant Barrier
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Solution Overview
Problem
Diffusion soldering techniques face challenges with mechanical pressure causing reduced yield and device failure due to contamination from pores formed in the front side metallization during the soldering process, which can lead to semiconductor device degradation or failure over time.
Innovation Solution
A method involving a contaminant protection layer between the front side metallization and the semiconductor body, which is designed to prevent transmission of contaminants and is mechanically protected by additional layers to remain intact during the soldering process, using specific metal and dielectric layers with tailored properties to form a conductive contact and absorb mechanical pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical pressure is applied during diffusion soldering to form strong intermetallic phases, then the melting point and strength of the soldered joint is improved, but pores form in the front side metallization allowing contaminant transmission
Solution Approach 1:
A contaminant protection layer is introduced as an intermediary barrier between the front side metallization and the semiconductor body. This layer prevents contaminant transmission while allowing the mechanical pressure diffusion soldering process to proceed and form strong intermetallic phases in the soldered joint.
Solution Approach 2:
The front side layer stack is segmented into multiple functional layers: the front side metallization layer for electrical connection, the contaminant protection layer for barrier function, and additional protection layers for mechanical support. This segmentation allows each layer to perform its specific function without interfering with others.
2Manufacturing precision
If mechanical pressure is applied during diffusion soldering, then the intermetallic phase formation is improved, but device yield decreases due to contamination
Solution Approach 1:
The contaminant protection layer serves as a mediator that allows the mechanical pressure diffusion soldering process to achieve precise intermetallic phase formation while simultaneously preventing contaminant ingress that would reduce device yield.
Solution Approach 2:
The contaminant protection layer is prepared in advance on the front side metallization before the diffusion soldering process. This preliminary protective measure ensures that when mechanical pressure is applied during soldering, contaminants cannot enter the semiconductor body, thereby maintaining high device yield.
3Reliability
If a contaminant protection layer is added to prevent contaminant transmission, then device reliability is improved, but the structural complexity of the front side layer stack increases
Solution Approach 1:
The contaminant protection layer and additional protection layers are designed to serve multiple functions: they provide contaminant barrier protection, offer mechanical support during the diffusion soldering process, and maintain electrical isolation. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents contamination from reaching the semiconductor body, ensuring device reliability and performance by maintaining the integrity of the contaminant protection layer and reducing the risk of device failure from mechanical pressure-induced pores.
Implementation Method 1
performing a soldering process that reflows the region of solder material to form a soldered joint
Implementation Method 2
the contaminant protection layer is configured to prevent transmission of contaminants into the semiconductor body
Implementation Method 3
the soldering process comprises applying mechanical pressure to the front side metallization
Data Source
AI summary
A semiconductor assembly includes a substrate including a metal die attach surface, a semiconductor die that is arranged on the substrate, the semiconductor die being configured as a power semiconductor device and comprising a semiconductor body, a rear side metallization, and a front side layer stack, the front side layer stack comprising a front side metallization and a contaminant protection layer that is between the front side metallization and the semiconductor body, and a diffusion soldered joint between the metal die attach surface and the rear side metallization, the diffusion soldered joint comprising one or more intermetallic phases throughout the diffusion soldered joint, wherein the contaminant protection layer is configured to prevent transmission of contaminants into the semiconductor body.