SiC Semiconductor Die Metal Stack for Universal Die Attach
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Solution Overview
Problem
The existing semiconductor die attach technologies face inefficiencies and increased costs due to compatibility issues with different backside structures, requiring separate die attach operations for semiconductor dies with Au and AuSn backside structures, which complicates manufacturing and inventory logistics.
Innovation Solution
A semiconductor die with a universal backside featuring a metal stack comprising a eutectic solder layer and a noble metal layer, allowing compatibility with both sintering/gluing and soldering-based die attach methods, simplifying the attachment process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If semiconductor die use different backside structures (Au or AuSn) for different die attach methods, then compatibility with specific die attach processes is improved, but device complexity and manufacturing complexity increase due to multiple backside types
Solution Approach 1:
The patent applies universality by designing a single backside structure that can serve multiple die attach functions. The backside includes a first metal layer compatible with sintering/gluing processes and a second metal layer compatible with soldering processes, allowing the same semiconductor die to be attached using either method without requiring different backside structures.
Solution Approach 2:
The backside structure is segmented into multiple metal layers with different properties. The first metal layer (e.g., Ag, Al, or Cu) provides compatibility with sintering/gluing processes, while the second metal layer (e.g., Au or Sn) provides compatibility with soldering processes. This segmentation allows each layer to fulfill specific functional requirements.
2Adaptability or versatility
If semiconductor die use different backside structures for different die attach methods, then compatibility with specific die attach processes is improved, but manufacturing efficiency and inventory management deteriorate due to separate die attach operations
Solution Approach 1:
The multi-functional backside structure allows a single die design to be used across different attach methods (sintering, gluing, or soldering), enabling manufacturers to choose the most efficient process without maintaining separate inventories of differently-backed dies.
Solution Approach 2:
The patent merges the functionality of multiple specialized backside structures into a single unified structure. By combining multiple metal layers with different compatibilities into one backside, the patent eliminates the need for separate die variants, streamlining manufacturing and inventory management.
3Adaptability or versatility
If semiconductor die use different backside structures for different die attach methods, then compatibility with specific die attach processes is improved, but manufacturing costs increase due to multiple backside types
Solution Approach 1:
The universal backside structure reduces manufacturing costs by eliminating the need to produce and manage multiple types of semiconductor dies with different backside structures. A single die design can be manufactured and then attached using any of the supported methods (sintering, gluing, or soldering).
Solution Approach 2:
The backside uses a composite metal layer structure where different metal layers are combined to achieve compatibility with multiple die attach processes. This composite approach allows a single structure to replace what would otherwise require multiple specialized structures.
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
This solution enables efficient, cost-effective, and compatible die attach operations for a wide range of power products, improving manufacturing efficiency and inventory management by using a single universal backside structure for various semiconductor die types.
Implementation Method 1
The final metal layer is configured to diffuse into the eutectic solder layer during at least a partial phase transition of the eutectic solder layer from a solid to a liquid state that happens during a die attach
Implementation Method 2
The final metal layer is configured to diffuse into the eutectic solder layer during at least a partial phase transition of the eutectic solder layer from a solid to a liquid state
Data Source
AI summary
A semiconductor die includes a silicon carbide (SiC) substrate and a metal stack. The SiC substrate has a first surface including a semiconductor layer thereon and a second surface that is opposite the first surface. The metal stack has an upper surface that attaches to the second surface of the SiC substrate and a lower surface that is opposite the upper surface. The metal stack includes a eutectic solder layer and a noble metal layer on the eutectic solder layer. The noble metal layer comprises a final metal layer on the lower surface.