3D DRAM Stack Bonding With Thermal Isolation Layers
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Solution Overview
Problem
In Integrated Circuit (IC) devices, the performance and functionality are hindered by degrading wire performance due to scaling, which affects power consumption and efficiency, and existing 3D stacking techniques face challenges in cost, complexity, and thermal management.
Innovation Solution
The method involves constructing 3D IC systems through layer transfer techniques using SiGe as a sacrificial layer for epitaxial-based 'cut' processes, enabling oxide-to-oxide and conductor-to-conductor bonding, and incorporating thermal isolation layers to manage temperature differences between strata, allowing for efficient integration of memory and logic circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire lengths are reduced through 3D stacking, then performance and functionality improve, but manufacturing complexity increases
Solution Approach 1:
The patent divides the 3D IC manufacturing process into distinct segments: forming sacrificial layers on donor wafers, transferring active device layers to target wafers, and selectively removing sacrificial material. This segmentation allows each step to be optimized independently, reducing overall manufacturing complexity while achieving the performance benefits of 3D stacking.
Solution Approach 2:
The patent introduces sacrificial layers (oxide or nitride) as intermediary elements that facilitate the layer transfer process. These sacrificial layers act as temporary placeholders that enable precise positioning and bonding of active device layers, then are selectively removed to complete the transfer. This intermediary approach simplifies the manufacturing process by providing a controlled mechanism for layer manipulation.
2Use of energy by moving object
If multiple layers are stacked to reduce wire lengths, then power consumption decreases, but thermal management becomes more difficult
Solution Approach 1:
The patent extracts and removes the sacrificial layers after they have served their positioning function during the transfer process. This extraction creates voids or spaces that can be filled with thermal management materials or used to improve heat dissipation pathways, thereby addressing thermal management challenges in multi-layer stacked structures.
Solution Approach 2:
The patent applies different material properties to different regions of the device. By selectively removing sacrificial material from specific areas, the structure achieves local variations in thermal conductivity and heat dissipation characteristics, optimizing thermal management in high-power regions while maintaining structural integrity elsewhere.
3Ease of manufacture
If conventional bonding methods are used for layer transfer, then process simplicity is maintained, but bonding strength and reliability are insufficient
Solution Approach 1:
The patent employs composite bonding approaches that combine oxide-to-oxide bonding with conductor-to-conductor bonding in the same structure. This composite methodology leverages the strengths of each bonding type: oxide bonding provides strong adhesion and electrical isolation, while conductor bonding ensures low-resistance electrical connections. The combination achieves superior overall bonding strength and reliability while maintaining process feasibility.
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 approach reduces wire lengths, enhances performance and functionality, lowers power consumption, and simplifies the fabrication process while maintaining thermal isolation, thereby improving the overall efficiency and yield of 3D IC devices.
Implementation Method 1
incorporating thermal isolation layers to manage temperature differences between strata
Implementation Method 2
bonding includes oxide to oxide and conductor to conductor bonding
Data Source
AI summary
A semiconductor device, the device including: a first level including a plurality of first memory arrays, where the first level includes a plurality of first transistors and a plurality of metal layers; a second level disposed on top of the first level, where the second level includes a plurality of second memory arrays, where the first level is bonded to the second level, where the bonded includes oxide to oxide bonding regions and a plurality of metal to metal bonding regions, where the plurality of first memory arrays includes a plurality of first DRAM (Dynamic Random Access Memory) cells, and where the plurality of second memory arrays includes a plurality of second DRAM (Dynamic Random Access Memory) cells.