Heat Dissipation Substrate With High Conductivity Layers
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Solution Overview
Problem
Current silicon semiconductor devices face inefficiencies in heat dissipation due to the low thermal conductivity of insulating layers and the limited effectiveness of thinning silicon substrates and external cooling methods.
Innovation Solution
A three-layer substrate structure is developed, comprising a surface layer of single crystal silicon with a second layer having higher thermal conductivity than silicon and a third layer with even higher conductivity, using materials like diamond, aluminum nitride, or silicon carbide, which are bonded and thinned to enhance heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a silicon substrate is thinned to improve heat dissipation, then the substrate thickness is reduced, but the device active layer still extends several microns from the surface creating a heat sump that reduces heat dissipation efficiency
Solution Approach 1:
The invention extracts the heat dissipation function from the silicon substrate by bonding a separate high thermal conductivity substrate (such as diamond, cubic silicon carbide, or silicon germanium) to the back surface. This external heat dissipation substrate is specifically designed to draw heat away from the device active layer, overcoming the limitation of thinning the original silicon substrate while maintaining device functionality.
Solution Approach 2:
The invention creates a composite substrate structure combining silicon with materials of higher thermal conductivity (diamond, cubic silicon carbide, or silicon germanium). This composite structure leverages the electrical properties of silicon while utilizing the superior heat dissipation capabilities of the bonded high-conductivity material, effectively resolving the contradiction between maintaining device active layer depth and improving heat dissipation.
2Reliability
If an insulating layer is interposed below the device active layer in SOI wafers to improve device performance, then device performance is enhanced, but heat dissipation is severely degraded due to the low thermal conductivity of the insulating layer
Solution Approach 1:
The invention introduces a high thermal conductivity substrate as an intermediary heat dissipation path. This external substrate acts as a mediator that provides an alternative route for heat flow, bypassing the insulating layer's thermal resistance. The high-conductivity material bonded to the back surface creates a dedicated heat extraction path that does not interfere with the insulating layer's electrical isolation function.
Solution Approach 2:
The invention shifts heat dissipation from a vertical path through the insulating layer to a lateral path through the bonded high-conductivity substrate. By bonding the heat dissipation function to the back surface, heat can be conducted laterally through the high-conductivity material and dissipated at the edges, effectively circumventing the thermal barrier presented by the insulating layer.
3Temperature
If external cooling methods such as water-cooled tubes or large fans are used to improve heat dissipation, then heat dissipation capability is enhanced, but device complexity and size increase
Solution Approach 1:
The invention merges the heat dissipation function directly into the substrate structure by bonding a high thermal conductivity material to the back surface. This integration eliminates the need for separate external cooling components such as water-cooled tubes or fans, as the substrate itself becomes the heat dissipation mechanism, thereby reducing device complexity while maintaining effective heat management.
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
The multilayer substrate structure significantly improves heat dissipation capabilities, surpassing the thermal conductivity of traditional silicon substrates and addressing the inefficiencies of existing methods.
Implementation Method 1
a second layer 2 having a higher thermal conductivity than silicon and a third layer 3 with a thermal conductivity which is higher than that of the first layer 1 and higher than or approximately equal to that of the second layer 2
Data Source
Figure 1~3C
Figure 4A~5C
Figure 6AA~7
AI summary
The present invention relates to a heat dissipation substrate, which is a composite substrate composed of two layers, and which is characterized in that a surface layer (first layer) (1) is configured of single crystal silicon and a handle substrate (second layer) (2) is configured of a material that has a higher thermal conductivity than the first layer. A heat dissipation substrate of the present invention has high heat dissipation properties.