Core-Shell Hybrid Bonding Structure for Low-Temperature Solder Joints
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Solution Overview
Problem
Existing semiconductor packaging methods using SAC-based solder face challenges with substrate damage due to high process temperatures, leading to tensile and compressive stresses that can result in solder joint damage.
Innovation Solution
The development of hybrid bonding structures utilizing a solder paste composition with a core-shell structure, where the core is a Sn-Ag-Cu alloy and the shell is made of bismuth or indium-silver, allowing for low-temperature bonding and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If SAC-based solder is used for bonding, then strong bonding strength is achieved, but substrate deformation and solder joint damage occur due to high process temperatures
Solution Approach 1:
The solder ball is segmented into a core-shell structure where the core provides bonding strength and the shell enables low-temperature bonding. This segmentation allows different functional requirements to be met by different parts of the same component, resolving the contradiction between bonding strength and temperature control.
Solution Approach 2:
The invention uses composite materials by combining SAC-based solder core with low-melting-point shell materials (Bi, In, Ga). This composite structure integrates the advantages of both materials: the core provides mechanical strength while the shell enables low-temperature bonding, thus resolving the contradiction between bonding strength and substrate deformation.
2Reliability
If high process temperature is used for SAC-based solder bonding, then reliable solder joints are formed, but tensile and compressive stresses damage the substrate
Solution Approach 1:
The invention changes the bonding temperature parameter from high (200-230°C for SAC) to low (below melting point of shell material). This parameter change allows reliable bonding to be achieved at lower temperatures, avoiding the thermal stresses that would otherwise damage the substrate while maintaining solder joint reliability.
3Object-affected harmful factors
If low-melting-point materials are used for low-temperature bonding, then substrate deformation is reduced, but bonding strength may be compromised
Solution Approach 1:
The segmentation of solder ball into core and shell allows the shell to handle the low-temperature bonding function while the core provides the bonding strength. This resolves the contradiction by assigning different functional roles to different segments of the same component.
Solution Approach 2:
The composite structure combines low-melting-point shell material with SAC-based core material. The shell reduces substrate deformation through low-temperature bonding while the core maintains bonding strength, thus resolving the contradiction between reducing substrate deformation and maintaining bonding strength.
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 approach enables bonding at lower temperatures, reducing substrate deformation and improving the mechanical properties of the solder joint, thereby enhancing the reliability and durability of semiconductor devices.
Implementation Method 1
The melting point of the shell may be in a temperature range of 150 °C to 200 °C
Implementation Method 2
A re-decomposition temperature of the intermetallic compound may be in a temperature range of about 400 °C to about 650 °C
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Provided are a hybrid bonding structure, a solder paste composition, a semiconductor device, and a method of manufacturing the semiconductor device. The hybrid bonding structure includes a solder ball and a solder paste bonded to the solder ball. The solder paste includes a transient liquid phase. The transient liquid phase includes a core and a shell on a surface of the core. A melting point of the shell may be lower than a melting point of the core. The core and the shell are configured to form an intermetallic compound in response to the transient liquid phase at least partially being at a temperature that is within a temperature range of about 20 °C to about 190 °C.