Porous Copper Layer Printing on Semiconductor Wafer
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Solution Overview
Problem
The deposition of copper layers on semiconductor wafers is hindered by thermal mechanical stress due to the different coefficients of thermal expansion of copper and silicon, leading to delamination and crack formation, and existing deposition processes for porous copper layers are complex and expensive.
Innovation Solution
A method involving printing a metal particle paste on a semiconductor wafer, followed by a heat treatment in a reductive gas atmosphere to sinter and anneal the paste, forming a thick, porous copper layer with reduced electrical resistivity and mechanical stress, using techniques like oven sintering and annealing in a nitrogen atmosphere saturated with formic acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper layer is deposited on silicon wafer, then electrical conductivity is improved, but thermal mechanical stress causes delamination and crack formation
Solution Approach 1:
The patent applies porous copper materials to reduce thermal mechanical stress. The porous structure allows for stress relief while maintaining electrical conductivity, preventing delamination and crack formation that occur with dense copper layers due to CTE mismatch between copper and silicon.
Solution Approach 2:
The patent uses composite material structures combining copper with porous configurations or additional layers. This composite approach balances the electrical conductivity benefits of copper with the mechanical stress resistance needed to prevent delamination, creating a multi-functional metallization layer.
2Strength
If porous copper layer is deposited to reduce thermal stress, then mechanical stress resistance is improved, but process complexity and cost increase
Solution Approach 1:
The patent replaces complex plasma or electro-chemical deposition processes with simpler printing-based deposition methods. This substitution maintains the ability to create porous copper structures while significantly reducing process complexity and cost, making porous copper fabrication more accessible.
Solution Approach 2:
The patent changes the deposition method parameters from complex plasma/electro-chemical processes to printing-based approaches. This parameter change achieves porous copper layer formation with reduced process complexity, lowering both equipment requirements and operational costs while maintaining stress resistance benefits.
3Ease of manufacture
If conventional deposition process is used, then process simplicity is maintained, but thermal mechanical stress causes delamination and cracking
Solution Approach 1:
The patent introduces porous copper materials that can be deposited using simplified printing processes. The porous structure inherently provides stress relief, maintaining layer stability and preventing delamination while keeping the manufacturing process simple and cost-effective.
4Reliability
If copper layer thickness is increased to reduce electrical resistance, then electrical conductivity is improved, but thermal mechanical stress increases
Solution Approach 1:
The patent employs porous copper structures that achieve low electrical resistance through optimized pore configurations and conductive pathways. The porous architecture reduces thermal mechanical stress by providing stress relief volume, allowing thicker effective copper layers without proportionally increasing stress, thus balancing conductivity improvement with stress management.
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 produces a stable, low-resistivity copper layer with reduced mechanical stress, improving the physical properties of the copper layer and extending the lifespan of electronic devices by achieving a stable microstructure through a longer heat treatment process.
Implementation Method 1
A heat treatment is performed within an atmosphere which includes a reductive gas for sintering the metal particle paste or for annealing the sintered metal particle paste
Implementation Method 2
A heat treatment is performed within an atmosphere which includes a reductive gas for sintering the metal particle paste
Implementation Method 3
A heat treatment is performed within an atmosphere which includes a reductive gas for sintering the metal particle paste or for annealing the sintered metal particle paste
Data Source
AI summary
A method for producing a metal layer on a wafer is described. In one embodiment the method comprises providing a semiconductor wafer including a coating, printing a metal particle paste on the semiconductor wafer thereby forming a metal layer and heating the metal layer in a reductive gas for sintering the metal particle paste or for annealing a sintered metal particle paste in an oven.