Oxide-Reduced Metal Interconnection for Solder-Free Die Attach
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Solution Overview
Problem
Current die attach solutions based on sintering of metallic nano- or micrometer sized particles are costly, complex, and result in thick, hard, and rigid interconnects due to micro- or nanocrystallinity, lacking the efficiency and flexibility of AuSn diffusion solder interconnects.
Innovation Solution
A method involving the use of a reducing agent to remove oxide layers on metallic layers of electric and electronic components, followed by direct connection under pressure and heat without solder, utilizing interconnection sublayers with varying surface roughness and malleability to form a solder-free, diffusion-based interconnect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sintering of metallic particles is used for die attach, then connection between components is achieved, but the interconnect becomes thick, hard, and rigid due to micro- or nanocrystallinity
Solution Approach 1:
The patent changes the physical-chemical parameters of the metallic layers by applying a reducing agent to remove oxide layers, followed by pressure and heat treatment. This transforms the surface state and crystalline structure of the metals, enabling direct diffusion bonding that produces a thinner, more flexible interconnect while maintaining strength.
Solution Approach 2:
The patent replaces the mechanical sintering process with a chemical-reduction and diffusion-based bonding mechanism. By removing oxide layers chemically and using direct metal-to-metal diffusion under pressure and heat, the process eliminates the need for particle sintering, resulting in a thinner and more flexible interconnect structure.
2Reliability
If sintering paste is used for die attach, then component connection is achieved, but the process cost becomes high and process complexity increases
Solution Approach 1:
The patent extracts and eliminates the sintering paste material from the process, using only the metallic layers already present on the components. By removing the need for additional paste materials and their associated dispensing, drying, and sintering steps, the process complexity is reduced while maintaining connection reliability through direct metal diffusion bonding.
Solution Approach 2:
The patent applies preliminary actions by pre-coating the metallic layers with reducing agents before the bonding step. This preliminary reduction of oxide layers ensures that the subsequent pressure and heat treatment can proceed directly to diffusion bonding without requiring complex in-process adjustments, simplifying the overall process while ensuring reliable connections.
3Reliability
If oxide layers are present on metallic layers, then component protection is achieved, but direct connection quality deteriorates due to oxidation
Solution Approach 1:
The patent converts the harmful oxide layers into beneficial reduced metal surfaces by applying reducing agents. The oxide layers that initially prevent good bonding are transformed through chemical reduction into clean, reactive metal surfaces that facilitate strong diffusion bonding, turning the harmful oxidation into a beneficial process step.
Solution Approach 2:
The patent introduces reducing agents as intermediary substances that mediate between the oxide-covered metallic layers and the desired direct metal-to-metal bond. The reducing agent temporarily interacts with the oxide layers to remove them, enabling the subsequent direct bonding without requiring complex vacuum or inert atmosphere conditions throughout the entire process.
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 method enables a cost-effective, flexible, and efficient interconnect with high electrical and thermal conductivity, allowing for fine pitch connections without material squeeze-out, while maintaining structural integrity and reducing processing complexity.
Implementation Method 1
disposing a reducing agent on one or both of the electronic component and the electric component such that the reducing agent is enabled to remove the oxide layer
Implementation Method 2
connecting the electronic component to the electric component by directly connecting the first layer of the electronic component with the second layer of the electric component by applying pressure and heat
Data Source
AI summary
A method of forming an interconnection includes: providing an electronic component having a first main face and a first metallic layer disposed on the first main face; providing an electric component having a second main face and a second metallic layer disposed on the second main face, at least one of the first or second metallic layers including an oxide layer provided on a main face thereof; disposing a reducing agent on one or both of the electronic component and the electric component such that the reducing agent is enabled to remove the oxide layer; and connecting the electronic component to the electric component by directly connecting the first metallic layer of the electronic component with the second metallic layer of the electric component by applying pressure and heat.