Low-Temperature Bump Bonding for Fine-Pitch Chip Interconnects
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Solution Overview
Problem
Existing bump bonding processes using high temperatures and large bump bonds are not compatible with temperature-sensitive integrated circuit components, which can be damaged by high temperatures and are not suitable for fine pitch interconnects.
Innovation Solution
A low temperature thermo-compression flip-chip bonding process is used to form mini-bumps on conductive contact pads, aligning and compressing them into larger bumps to create bump bond structures, allowing for concurrent bonding of gold and indium alloy interconnects at temperatures below 150°C, with a surface area ratio of 25:1, forming robust mechanical and electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature bump bonding process (300-450°C) is used, then robust metallic bond is achieved, but temperature-sensitive IC components are damaged
Solution Approach 1:
The patent changes the bonding temperature parameter from conventional high temperatures (300-450°C) to low temperatures (below 150°C), enabling bonding of temperature-sensitive IC components while maintaining reliable electrical and mechanical connections through controlled compression and material selection
2Reliability
If large bump bonds (50-100 μm diameter) are used, then robust bond is achieved, but fine pitch interconnects cannot be formed
Solution Approach 1:
The patent changes the bump size parameter from large dimensions (50-100 μm) to small dimensions (below 10 μm), enabling fine pitch interconnects while maintaining bond reliability through low temperature processing and precise compression control that ensures adequate contact area for electrical connection
3Object-affected harmful factors
If low temperature bonding process is used, then temperature-sensitive components are protected, but bonding reliability is reduced
Solution Approach 1:
The patent introduces an intermediary compression force mechanism that enables bonding at low temperatures by applying controlled pressure to facilitate metallurgical bonding without requiring high thermal energy, thus protecting temperature-sensitive components while achieving reliable bonds
Solution Approach 2:
The patent employs composite material structures including gold bumps, indium alloy interconnects, and complementary metal-oxide-semiconductor devices that are compatible with low temperature processing, enabling reliable bonding at temperatures below 150°C through material selection optimized for low temperature metallurgical bonding
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 process enables the formation of robust electrical and mechanical connections between integrated circuits at low temperatures, protecting temperature-sensitive components and supporting fine pitch interconnects, while maintaining a low resistance electrical contact.
Implementation Method 1
performing a bump bonding process that exerts compression force on one or both the first electronic device and the second electronic device to compress the one or more mini-bumps into the one or more bumps
Implementation Method 2
compress the one or more mini-bumps into the one or more bumps that form one or more bump bond structures to bond the second electronic device to the first electronic device
Data Source
AI summary
A method of forming a multi-chip system is disclosed. The method includes forming one or more bumps on respective conductive contact pads of a first electronic device, forming one or more mini-bumps on respective conductive contact pads of a second electronic device, and aligning respective one or more mini-bumps with respective one or more bumps. The method further includes performing a bump bonding process that exerts compression force on one or both the first electronic device and the second electronic device to compress the one or more mini-bumps into the one or more bumps to form one or more bump bond structures that bond the second electronic device to the first electronic device.