3D Semiconductor Stacked Metal Layers Thermal Management
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Solution Overview
Problem
Heat removal in 3D stacked integrated circuits is challenging due to high power density and thermal resistance, particularly as wiring dielectric regions do not conduct heat well, making it difficult to transfer heat effectively from transistors to the heat sink.
Innovation Solution
The implementation of thermal contacts and thermally conductive materials, such as copper or graphene, integrated into the power and ground distribution networks, and the use of thermally conductive shallow trench isolation and pre-metal dielectric regions to reduce thermal resistance and enhance heat spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 3D stacking of semiconductor devices is implemented to reduce wire lengths and improve transistor density, then transistor performance and density improve, but heat removal becomes significantly more difficult due to high power density and thermal resistance
Solution Approach 1:
The patent introduces vertical thermal pathways through the stacked device layers using thermally conductive materials and structures extending in the Z-dimension. Heat spreaders and thermal vias create three-dimensional heat dissipation pathways, moving heat removal from a two-dimensional surface problem to a three-dimensional volumetric solution that addresses the high power density in stacked configurations.
Solution Approach 2:
The patent employs composite thermal management structures combining multiple materials with different thermal conductivities. Heat spreaders use high thermal conductivity materials (such as diamond, cubic boron nitride, or metal alloys) combined with thermally conductive dielectric materials in the interlayer regions. This composite approach creates optimized thermal pathways while maintaining electrical isolation and structural integrity.
2Reliability
If wiring dielectric regions are used to insulate interconnects in 3D stacked devices, then electrical insulation is provided, but thermal conduction is poor making heat transfer from transistors to heat sink difficult
Solution Approach 1:
The patent applies local quality by creating regions with different thermal properties in specific locations. Thermally conductive dielectric materials are selectively placed in interlayer regions and around heat-generating structures, while standard dielectric materials are used in other areas. This localized approach provides electrical insulation where needed while enhancing thermal conduction in critical heat pathways.
Solution Approach 2:
The patent introduces thermally conductive dielectric materials as intermediary substances between the wiring dielectric regions and the heat-generating transistor structures. These intermediary materials serve dual functions: maintaining electrical insulation properties while providing enhanced thermal conduction pathways, effectively bridging the gap between electrical isolation requirements and thermal management needs.
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 effectively reduces thermal resistance, allowing for efficient heat transfer from transistors to the heat sink, maintaining desirable temperatures and improving the thermal management of 3D integrated circuits.
Implementation Method 1
The implementation of thermal contacts and thermally conductive materials, such as copper or graphene, integrated into the power and ground distribution networks
Implementation Method 2
the use of thermally conductive shallow trench isolation and pre-metal dielectric regions to reduce thermal resistance and enhance heat spreading
Data Source
AI summary
A method for producing a 3D semiconductor device: providing a first level with a first single crystal layer; forming a plurality of first transistors in and/or on the first level with a first metal layer above; forming a second metal layer above the first metal layer; forming a third metal layer above the second metal layer; forming at least one second level on top of or above the third metal layer; performing a first etch step; performing additional processing steps to form a plurality of second transistors within the second level; forming a fourth metal layer above; forming a connection to the second metal layer which includes a via through the second level; forming a fifth metal layer above, where some second transistors include a metal gate, and the fifth metal layer thickness is at least 50% greater than the second metal layer thickness.