3D Semiconductor Thermal Contacts for Heat Removal
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Solution Overview
Problem
Three-dimensional integrated circuits (3D-ICs) face significant challenges in heat removal due to increased power density and high thermal resistance, particularly in stacked configurations where heat transfer from semiconductor layers to heat sinks is hindered by the distance and poor conductivity of wiring dielectric regions.
Innovation Solution
The implementation of thermal contacts and thermally conductive materials, such as copper and diamond, integrated into the 3D-IC structure to create low-thermal resistance paths for heat transfer from transistors to the heat removal apparatus, along with the use of thermally conductive shallow trench isolation and pre-metal dielectric regions to enhance heat spreading and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple layers of transistors are stacked in 3D configuration, then transistor density and performance are improved, but heat removal becomes significantly more difficult due to increased power density and thermal resistance
Solution Approach 1:
The patent introduces vertical thermal pathways through the stacked layers by forming thermal contacts that extend in the z-direction (vertical dimension) from the heat generating transistor regions through the interlayer dielectric to the heat removal apparatus. This dimensional approach to heat removal complements the traditional planar heat dissipation, enabling effective thermal management in 3D stacked configurations by utilizing the vertical space dimension that was previously underutilized for thermal transport.
2Reliability
If wiring dielectric regions are used to isolate transistor layers, then electrical insulation is achieved, but thermal conductivity deteriorates due to poor heat transfer properties of dielectric materials
Solution Approach 1:
The patent introduces thermal contacts as intermediary structures that bridge the thermal gap created by the wiring dielectric regions. These thermal contacts are formed through the interlayer dielectric material and provide a dedicated thermal conduction pathway that mediates between the heat generating transistor regions and the heat removal apparatus, overcoming the thermal insulation barrier while maintaining electrical isolation.
Solution Approach 2:
The thermal contacts are formed using composite material structures including copper fill within via holes, surrounded by dielectric materials, and integrated with the interlayer dielectric regions. This composite approach combines materials with high thermal conductivity (copper) with electrical insulation properties (dielectric materials), achieving both thermal transport and electrical isolation functions simultaneously within the same structural element.
3Speed
If transistors are placed closer together in 3D stacking, then wire lengths are reduced and wiring delay is minimized, but power density increases leading to greater heat generation
Solution Approach 1:
The patent addresses the increased power density from close-spaced 3D transistor stacking by introducing vertical thermal transport pathways that extend through the stacked layers. The thermal contacts provide direct thermal conduction routes in the vertical dimension, enabling heat to be removed from densely packed transistor regions without being constrained by planar heat dissipation limitations, thus supporting higher power densities achievable through 3D integration.
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 significantly reduces thermal resistance and enables effective heat removal from 3D-ICs, maintaining transistor temperatures within desirable limits and improving the overall thermal management of 3D stacked devices.
Implementation Method 1
thermal contacts and thermally conductive materials, such as copper and diamond, integrated into the 3D-IC structure to create low-thermal resistance paths for heat transfer from transistors to the heat removal apparatus
Implementation Method 2
thermally conductive shallow trench isolation and pre-metal dielectric regions to enhance heat spreading and conductivity
Data Source
AI summary
A 3D semiconductor device, the device including: a first level, where the first level includes a first layer, the first layer including first transistors, and where the first level includes a second layer, the second layer including first interconnections; a second level overlaying the first level, where the second level includes a third layer, the third layer including second transistors, and where the second level includes a fourth layer, the fourth layer including second interconnections; and a plurality of connection paths, where the plurality of connection paths provides connections from a plurality of the first transistors to a plurality of the second transistors, where the second level is bonded to the first level, where the bonded includes oxide to oxide bond regions, where the bonded includes metal to metal bond regions, where the third layer includes a crystalline layer, and where the second level includes a Radio Frequency (“RF”) circuit.