3D IC Cooling via TSV and Microvia Thermal Paths
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Solution Overview
Problem
Three-dimensional integrated circuits (3-D ICs) face challenges in efficiently dissipating heat generated during operation, leading to elevated chip temperatures, reduced performance, and reliability issues due to thermal resistance and heat retention within the semiconductor material and inter-chip interfaces.
Innovation Solution
The implementation of through-silicon vias (TSVs) and thermally conductive microvias with patterned regions of thermally conductive material on the backside of the chip, along with a method for fabricating and assembling these structures, creates an efficient heat transfer path by conducting heat from active devices to the exterior surface, utilizing materials with higher thermal conductivity than semiconductor materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional semiconductor cooling structures are used, then the chip structure is simple, but heat dissipation efficiency is poor leading to elevated temperatures
Solution Approach 1:
The cooling structure is segmented into multiple functional components: TSVs for vertical heat transport, microvias for lateral heat distribution, and thermally conductive material regions for heat spreading. This segmentation allows each component to optimize its function, resulting in superior overall heat dissipation performance compared to traditional unified cooling structures.
Solution Approach 2:
The invention employs composite material structures combining semiconductor material with high-thermal-conductivity materials (such as metal-filled vias and thermally conductive epoxies). This composite approach creates thermal pathways with conductivity significantly higher than pure semiconductor material, effectively reducing thermal resistance and chip operating temperature.
2Reliability
If TSVs and microvias are added to improve heat dissipation, then thermal resistance is reduced, but device complexity increases
Solution Approach 1:
TSVs serve dual functions: electrical interconnection between stacked chips and vertical heat conduction pathways. Microvias provide both electrical connectivity and lateral heat distribution. This multi-functionality reduces the need for separate dedicated cooling structures, thereby managing complexity while improving heat dissipation efficiency.
Solution Approach 2:
The invention merges the electrical interconnection function with the thermal management function by using the same TSV and microvia structures for both purposes. The thermally conductive material regions are integrated into existing interconnect layers, combining electrical and thermal pathways rather than requiring separate systems.
3Temperature
If high thermal conductivity materials are used in vias, then heat transfer efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The invention changes the thermal conductivity parameter of via fill materials from standard semiconductor-grade materials to high-thermal-conductivity materials (such as copper, aluminum, or specialized thermal epoxies). This parameter change significantly improves heat transfer efficiency while utilizing established via fabrication processes.
Solution Approach 2:
Thermally conductive material regions are formed in advance during the interconnect fabrication process, before final chip assembly. This preliminary action integrates thermal management into the standard manufacturing flow, avoiding the need for post-fabrication thermal modification and simplifying overall manufacturing.
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 effectively reduces thermal resistance, allows for higher heat dissipation, and enables 3-D ICs to operate at lower temperatures, increasing performance and reliability while being cost-effective and compatible with existing fabrication technologies.
Implementation Method 1
Each microvia of the plurality of microvias may have a second depth, from the back side towards the active devices, that is less than the first depth and a fill material having a fill thermal conductivity greater than a semiconductor material thermal conductivity
Implementation Method 2
a plurality of through-silicon vias (TSVs) electrically connected to the active devices, extending from the back side to an active device side of the first chip and configured to remove, by conduction from the active devices to the back side, heat from the first chip
Implementation Method 3
The structure may also include a plurality of thermally conductive material regions on the back side of the first chip, each region of the plurality of regions in contact with a respective set of the plurality of microvias
Data Source
AI summary
A chip fabricated from a semiconductor material is disclosed. The chip may include active devices located below a first depth from a chip back side and a structure configured to remove heat from the chip. The structure may include microvias electrically insulated from the active devices and having a second depth, less than the first depth, from the back side towards the active devices. Each microvia may also have a fill material having a thermal conductivity greater than a semiconductor thermal conductivity. The structure may also include thermally conductive material regions on the back side of the chip in contact with sets of microvias. The structure may also include through-silicon vias electrically connected to the active devices, and extending from the back side to an active device side of the chip and configured to remove heat from the active devices to the back side of the chip.