Au-Based Solder Die Attachment Joint Strength
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Solution Overview
Problem
Conventional Au-based solder die attachment in semiconductor devices experiences a reduction in joint strength over time when used at high temperatures, leading to potential detachment of the semiconductor chip from the plating layer.
Innovation Solution
A dense metal film with fine slits is applied between the Cu substrate and the Au-based solder layer, and fine structures with a dumbbell-like cross section, primarily composed of Cu and Au, are buried within these slits to enhance the connection between the Au-based solder layer and the Cu substrate, preventing joint strength deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a dense plating of Ni is applied to the Cu substrate as a barrier metal, then the initial joint strength is improved, but the joint strength deteriorates over time at high temperature
Solution Approach 1:
The dense metal film is segmented with fine slits patterned throughout its structure. These slits create multiple discrete regions that prevent continuous crack propagation, thereby maintaining joint strength over extended high-temperature service life while preserving the barrier metal function
Solution Approach 2:
The dense metal film incorporates a network of fine slits creating a controlled porous structure. This porous configuration allows the metal to maintain density and barrier properties while accommodating thermal expansion differences and preventing stress concentration that would lead to deterioration
2Temperature
If high melting point Au-based solder is used, then the melting temperature is improved, but the joint strength reduces over time at high temperature
Solution Approach 1:
The invention creates a composite structure where the Au-based solder layer is combined with the dense metal film containing fine slits. This composite configuration allows the high melting point solder to maintain its temperature resistance while the dense metal film with slits provides enhanced mechanical strength and crack resistance at operating temperatures
Data Source
AI summary
A semiconductor device according to the present invention, having an Au-based solder layer (3) sandwiched between a semiconductor element (1) and a Cu substrate (2) made mainly of Cu, in which the semiconductor device includes: a dense metal film (23) which is arranged between the Cu substrate (2) and the Au-based solder layer (3), and has fine slits (24) patterned to have a predetermined shape in a plan view; and fine structures (4) with dumbbell-like cross section, which have Cu and Au as main elements, and are each buried in the Cu substrate (2), the Au-based solder layer (3), and the fine slits (24) of the dense metal film (23).