Semiconductor Package Bonding Structure With Solid Solution Layer
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Solution Overview
Problem
In semiconductor package structures, alignment shifts during bonding processes can lead to gaps between conductive pillars and recessed conductive layers, affecting electrical connections due to non-coplanar bonding surfaces.
Innovation Solution
A semiconductor package structure is developed with a solid solution layer that electrically connects metal layers, using a protrusion on one substrate and a recess on the other, where the solid solution layer is formed by heating a bonding material with a first metal and a second composition having a lower melting point, transforming any intermetallic compounds into a solid solution layer for improved bonding and reduced brittleness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a lock and key structure with conductive pillar and recessed conductive layer is used for metal-to-metal bonding, then alignment shifts are reduced and mechanical strength is improved, but gaps are formed between the pillar bottom and recess due to non-coplanar bonding surfaces, adversely affecting electrical connection
Solution Approach 1:
A solid solution layer is introduced as an intermediary between the conductive pillar and the recessed conductive layer. This layer fills the gap caused by non-coplanar surfaces and provides both mechanical support and electrical conductivity, simultaneously improving mechanical strength and electrical connection reliability without compromising the lock-and-key alignment structure
Solution Approach 2:
The bonding structure is transformed from a simple metal-to-metal interface to a composite structure consisting of the conductive pillar, solid solution layer, and recessed conductive layer. The solid solution layer acts as a composite material that combines mechanical filling capability with electrical conductivity, resolving the contradiction between mechanical strength and electrical connection
2Strength
If intermetallic compounds are formed during bonding process, then bonding strength is initially improved, but the compounds are brittle and reduce the reliability of the bonding structure
Solution Approach 1:
The bonding process parameters are changed by implementing a two-stage heating process: first forming intermetallic compounds at elevated temperature to establish bonding strength, then performing a solid solution mixing operation at a higher temperature to transform the brittle intermetallic compounds into a ductile solid solution layer, thereby improving reliability while maintaining strength
Solution Approach 2:
The bonding material undergoes phase transitions during the two-stage heating process. Initially, intermetallic compounds form through solid-state reaction, then at the higher solid solution mixing temperature, these compounds transform into a solid solution phase through diffusion and mixing, changing from brittle to ductile and improving bonding reliability
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 enhances the conductive contact area and uniformity of electrical connections, reducing resistance deviations to less than or equal to ±10%, while providing high mechanical strength and reliability by eliminating brittle intermetallic compounds and facilitating a pre-bonding process with transient liquid phase bonding.
Implementation Method 1
The solid solution layer electrically connects the first metal layer to the second metal layer
Implementation Method 2
performing a solid solution mixing operation by heating the first metal layer and the bonding material to a second temperature that is higher than the first temperature
Implementation Method 3
performing a pre-bonding operation by heating the first metal layer and the bonding material to a first temperature
Data Source
AI summary
A semiconductor package structure and a method for manufacturing a semiconductor package structure are provided. The semiconductor package structure includes a first substrate, a second substrate, and a solid solution layer. The first substrate includes a first metal layer, and the first metal layer includes a first metal. The second substrate includes a second metal layer. The solid solution layer electrically connects the first metal layer to the second metal layer. The solid solution layer includes a first metal-rich layer.