Ultra-Fine Pitch Copper Nanoparticle Interconnects for Precise Bonding
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Solution Overview
Problem
Conventional lead-free solder bumping technologies face challenges in achieving precise alignment and high-density packaging due to larger spacing requirements, which restricts the development of ultra-fine pitch interconnections and high-density three-dimensional packaging, and copper pillars cause high interconnection temperature and poor alignment.
Innovation Solution
The method involves preparing ultra-fine copper nanoparticles by vapor deposition, transferring them to a substrate, and using hot-pressing sintering to bond a chip with copper pillars to the substrate, while oxidizing and cleaning to achieve a low-temperature and low-pressure interconnect structure with improved positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If copper pillars are used for ultra-fine pitch interconnection, then interconnection strength and electrical conductivity are improved, but interconnection temperature increases and alignment precision deteriorates
Solution Approach 1:
The patent changes the material parameters from conventional copper pillars to copper nanowires with controlled diameter (50-200 nm) and aspect ratio. This parameter change enables lower interconnection temperature while maintaining strength, and the flexible nanowire structure accommodates alignment variations in ultra-fine pitch applications
Solution Approach 2:
The patent replaces the rigid mechanical copper pillar structure with flexible copper nanowire interconnects that can bend and conform to misaligned surfaces. This substitution of mechanical rigidity with flexibility allows the nanowires to bridge gaps between misaligned chip and substrate pads, solving the alignment precision problem while maintaining electrical conductivity
2Ease of manufacture
If lead-free solder bumps are used for interconnection, then ease of manufacture is improved, but spacing requirements increase which limits I/O port density
Solution Approach 1:
The patent changes the interconnection geometry from spherical solder bumps to wire-like copper nanowires with high aspect ratio. This parameter change allows the nanowires to bridge larger vertical gaps while occupying minimal horizontal space, enabling higher I/O port density on the same substrate area while maintaining ease of manufacture through direct growth methods
3Measurement precision
If copper nanoparticles are used for low-temperature interconnection, then positioning accuracy is improved, but oxidation resistance deteriorates
Solution Approach 1:
The patent employs inert atmosphere protection during the vapor deposition process to prevent copper nanoparticle oxidation. By controlling the deposition environment with inert gas (such as nitrogen or argon), the copper nanoparticles maintain their metallic state and electrical conductivity while achieving the required positioning accuracy on the substrate
Solution Approach 2:
The patent introduces a protective layer or coating as an intermediary between the copper nanoparticles and the oxidizing environment. This intermediate layer protects the copper from oxidation while allowing the nanoparticles to maintain their precise positions and electrical function in the interconnection structure
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 enhances positioning accuracy and enables high-density packaging by controlling copper nanoparticle size and preventing oxidation, resulting in improved thermoelectric interconnection performance and reliability without using toxic chemicals.
Implementation Method 1
preparing copper nanoparticles by vapor deposition method using a vapor deposition device
Implementation Method 2
a coupling parameter of the vapor deposition device is adjusted to control an initial particle size of the copper nanoparticles
Implementation Method 3
subjecting the copper pillars to hot-pressing sintering to allow the chip to be bonded with the substrate
Implementation Method 4
subjecting the copper pillars to hot-pressing sintering
Implementation Method 5
oxidizing copper nanoparticles in areas not in contact with the copper pillars into copper oxide particles
Data Source
AI summary
This application relates to semiconductor manufacturing, and more particularly to an interconnect structure for semiconductors with an ultra-fine pitch and a forming method thereof. The forming method includes: preparing copper nanoparticles using a vapor deposition device, where coupling parameters of the vapor deposition device are adjusted to control an initial particle size of the copper nanoparticles; depositing the copper nanoparticles on a substrate; invertedly placing a chip with copper pillars as I/O ports on the substrate; and subjecting the chip and the substrate to hot-pressing sintering to enable the bonding.