Atmospheric Plasma Chip Bonding Without Flux Oxide Removal
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Solution Overview
Problem
The formation of oxides on metal bumps and bonding pads hinders the formation of secure bonds during the direct bonding process of integrated circuit dies to package substrates, which is a challenge in three-dimensional semiconductor devices.
Innovation Solution
A system is configured to expose the metal bumps and bonding pads to a plasma in a controlled environment with low oxygen concentration to remove oxides, followed by aligning and applying compressive force and heat to facilitate bonding without the need for solder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct bonding process is used to bond integrated circuit dies to package substrates, then bonding speed and integration density are improved, but oxide formation on metal bumps and bonding pads hinders secure bond formation
Solution Approach 1:
The patent applies preliminary plasma treatment to the metal bumps and bonding pads before the bonding process to remove oxides in advance. This preliminary oxidation removal ensures that the surfaces are clean and ready for bonding, preventing oxide interference during the actual bonding operation and enabling both high-speed processing and reliable bond formation.
Solution Approach 2:
The patent employs a plasma environment that creates a locally controlled atmosphere during the bonding process. The plasma treatment generates a reactive environment that removes oxides while the subsequent rapid bonding occurs before re-oxidation can happen, effectively creating a protective window for oxide-free bonding.
2Ease of manufacture
If flux is used to remove oxides during bonding, then oxide removal is achieved, but additional process steps and materials are required
Solution Approach 1:
The patent replaces the mechanical/chemical flux application process with a plasma-based field process. Instead of applying flux materials mechanically and then removing them, the patent uses plasma energy to directly remove oxides through chemical reactions in the plasma environment, eliminating the need for flux materials and their associated application and removal steps.
Solution Approach 2:
The patent changes the physical and chemical parameters of the bonding environment by introducing plasma. This parameter change enables oxide removal through plasma chemistry rather than flux chemistry, transforming the process from a multi-step flux-based approach to a more integrated plasma-assisted bonding process that reduces overall process complexity.
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 ensures secure and reliable bonding by eliminating oxides, thereby enhancing the electrical and mechanical coupling of integrated circuit dies to package substrates.
Implementation Method 1
A system is configured to expose the metal bumps and bonding pads to a plasma in a controlled environment with low oxygen concentration to remove oxides
Implementation Method 2
applying compressive force and heat to facilitate bonding without the need for solder
Data Source
AI summary
A disclosed system is configured to bond a chip to a substrate and includes a chip processing subsystem that is configured to receive the chip and to expose the chip to a first plasma, and a substrate processing subsystem that is configured to receive the substrate and to expose the substrate to a second plasma. The system further includes a bonding subsystem that is configured to align the chip with the substrate, to force the chip and the substrate into direct mechanical contact with one another by application of a compressive force, and to apply heat to at least one of the chip or the substrate. Application of the compressive force and the heat thereby bonds the chip to the substrate. The first and second plasmas may include H2/N2, H2/Ar, H2/He, NH3/N2, NH3/Ar, or NH3/He and the chip and substrate may be maintained in a low oxygen environment.