Barrier Layer for Interconnects in 3D Integrated Devices
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Solution Overview
Problem
The formation of intermetallic compounds between vertically stacked electronic devices during high-temperature treatments leads to volumetric expansion, causing separation and voids that interrupt the electrical path, making it difficult to predict long-term functionality and increasing waste and costs in the direct bond approach.
Innovation Solution
A barrier layer is interposed between the electrical trace and interconnect to prevent intermetallic compound formation, allowing for multiple high-temperature treatments and early detection of failures in the stacked electronic device assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature treatment is applied to bond vertically stacked electronic devices, then diffusion bonding between interconnects is improved, but intermetallic compound formation causes volumetric expansion leading to separation and voids that interrupt electrical paths
Solution Approach 1:
A barrier layer is introduced as an intermediary component between the electrical trace and interconnect structure. This barrier layer prevents direct contact and intermetallic compound formation between dissimilar metals (e.g., nickel and aluminum) while still allowing diffusion bonding to occur between like metals (nickel-to-nickel) across the bonded interfaces, thus maintaining electrical path continuity during high-temperature treatment
Solution Approach 2:
The interface region between trace and interconnect is segmented into multiple functional layers: the trace layer, the barrier layer, and the interconnect structure. This segmentation isolates the dissimilar metals from direct interaction while preserving the necessary electrical and mechanical connections through the stacked device assembly
2Productivity
If multiple high-temperature treatments are conducted during direct bond processing, then bonding between stacked devices is improved, but intermetallic compound formation increases causing volumetric expansion and separation
Solution Approach 1:
The barrier layer serves as a thermal and diffusion barrier that allows multiple high-temperature treatments to be applied for bonding stacked devices while preventing the formation of volumetrically expanding intermetallic compounds. This enables repeated thermal processing without compromising the dimensional stability of the joint regions
Solution Approach 2:
The introduction of the barrier layer changes the material composition and thermal response parameters of the interface region, allowing the system to withstand multiple high-temperature cycles without the detrimental volumetric expansion associated with intermetallic compound formation
3Force
If intermetallic compounds form between interconnect and trace materials, then contact between stacked devices is improved, but the brittle low-density compound causes volumetric expansion that may cause separation or voids
Solution Approach 1:
The barrier layer acts as an intermediary that prevents the formation of brittle intermetallic compounds while still enabling adequate contact and bonding between stacked devices. This eliminates the risk of volumetric expansion causing separation or voids in the joint region
4Adaptability or versatility
If dissimilar metals are used for interconnect and trace, then electrical functionality is improved, but intermetallic compound formation occurs during high-temperature treatment
Solution Approach 1:
The barrier layer is positioned between dissimilar metal materials (e.g., aluminum trace and nickel interconnect) to prevent intermetallic compound formation while still allowing the dissimilar metals to be used for their respective electrical functionality in the stacked device assembly
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 solution enables reliable electrical communication and reduces scrap by allowing functional testing earlier in the process, improving yield and cost-effectiveness in vertically stacked electronic devices.
Implementation Method 1
a barrier layer interposed between an electrical trace and an electrical interconnect for restricting interdiffusion between the interconnect and trace materials
Implementation Method 2
the bonding layer of one electronic device is contacted with the bonding layer of another electronic device, whereby a chemical bond may occur with or without temperature treatment
Implementation Method 3
the stacked electronic device assembly undergoes a relatively high-temperature treatment to cause the vertical interconnects from each electronic device to be sufficiently diffusion bonded together
Implementation Method 4
the lower density of the intermetallic compound may cause volumetric expansion in the joint region between the interconnect and trace
Data Source
AI summary
An electronic device integration method and integrated electronic device. The integration method may include the steps of preparing a first electronic device by forming an electrically conductive trace overlying a substrate, forming a barrier layer overlying the electrically conductive trace, forming one or more electrically conductive interconnects on the barrier layer, and forming a bonding layer overlying the trace and/or at least partially surrounding the one or more interconnects. The barrier layer is configured to prevent formation of an intermetallic compound between the trace and interconnect structures, while still enabling electrical communication between the trace and interconnect. The integration method may further include the steps of direct bonding the first electronic device to a second electronic device, direct bonding a third electronic device to the second electronic device, and so on. A high-temperature treatment and functional testing of the vertically integrated electronic device may be conducted after each stack sequence.