3D IC Backside Contacts for Heat Dissipation Without Added Stack Height
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Solution Overview
Problem
In three-dimensional (3D) integrated circuits, heat generated from semiconductor devices can become trapped due to insufficient thermal dissipation, leading to potential damage and performance degradation, especially in multi-layer stacks where heat build-up is exacerbated.
Innovation Solution
The implementation of backside contacts on the semiconductor substrates, which are strategically positioned to enhance heat dissipation without increasing the vertical dimensions of the IC stack, by being arranged below the topmost surface of through substrate vias and coupled to interconnect structures, allowing heat to dissipate efficiently away from the semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If through substrate vias are used for heat dissipation, then thermal dissipation is improved, but vertical dimensions of the IC stack increase
Solution Approach 1:
The patent introduces backside contacts as an additional thermal dissipation dimension. Instead of relying solely on vertical through substrate vias, the invention creates thermal pathways extending from the backside surface of the substrate, allowing heat to dissipate in a different spatial dimension without increasing the vertical height of the IC stack.
Solution Approach 2:
The thermal dissipation system is segmented into multiple independent pathways: through substrate vias for vertical heat removal and backside contacts for surface-level heat dissipation. This segmentation allows each component to perform its thermal management function independently, improving overall heat dissipation efficiency without compromising vertical dimension constraints.
2Productivity
If integration density is increased by reducing minimum feature sizes, then circuit density per area is improved, but thermal dissipation becomes more challenging
Solution Approach 1:
As circuit density increases and generates more heat per unit area, the invention provides additional thermal dissipation pathways by extending thermal management structures to the backside surface of the substrate. This creates extra surface area for heat removal without consuming additional planar space, thereby maintaining high circuit density while improving thermal management.
Solution Approach 2:
The backside contacts serve multiple functions: they provide electrical connectivity to the interconnect structure while simultaneously acting as thermal dissipation pathways. This multi-functionality allows the same structural elements to address both signaling and thermal management challenges in high-density circuits.
3Temperature
If backside contacts are positioned to maximize heat dissipation, then thermal dissipation efficiency is improved, but electrical interference with semiconductor devices may occur
Solution Approach 1:
The backside contacts are strategically positioned in specific local regions of the substrate backside surface, away from the projected areas of the semiconductor devices. This localized placement ensures that thermal dissipation occurs in regions that do not interfere with the electrical operation of the devices, separating thermal and electrical functional zones.
Solution Approach 2:
The interconnect structure embedded within the substrate serves as an intermediary element that couples the backside contacts to the semiconductor devices. This intermediary provides the necessary electrical connectivity for thermal management while maintaining proper electrical isolation and signaling functions, preventing direct interference between thermal dissipation pathways and device operation.
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 provides a more efficient heat dissipation path compared to traditional through substrate vias, reducing thermal degradation and improving the lifetime of the 3D IC stack without altering its layout or dimensions.
Implementation Method 1
a backside contact arranged within the bonding structure and coupled to the bonding wire layers and the bonding vias of the bonding structure, wherein a bottommost surface of the backside contact is thermally coupled to the backside of the semiconductor substrate
Data Source
AI summary
In some embodiments, the present disclosure relates to a 3D integrated circuit (IC) stack that includes a first IC die bonded to a second IC die. The first IC die includes a first semiconductor substrate, a first interconnect structure arranged on a frontside of the first semiconductor substrate, and a first bonding structure arranged over the first interconnect structure. The second IC die includes a second semiconductor substrate, a second interconnect structure arranged on a frontside of the second semiconductor substrate, and a second bonding structure arranged on a backside of the second semiconductor substrate. The first bonding structure faces the second bonding structure. Further, the 3D IC stack includes a first backside contact that extends from the second bonding structure to the backside of the second semiconductor substrate and is thermally coupled to at least one of the first or second interconnect structures.