Si Substrate Via Hole Metal Layer Heat Dissipation
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Solution Overview
Problem
Semiconductor devices with silicon substrates face challenges in heat dissipation due to silicon's lower thermal conductivity compared to silicon carbide, necessitating additional arrangements to manage heat from nitride-based active devices effectively.
Innovation Solution
A semiconductor device and process involving a silicon substrate with a via hole and a metal layer covering the back surface and via hole interior, allowing direct contact between the active device and the metal layer for enhanced heat dissipation, using a multi-layered metal structure comprising gold, molybdenum, and copper to match thermal expansion and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a silicon carbide substrate is used, then heat dissipation performance is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent employs a composite structure combining silicon substrate with metal layers (copper, molybdenum, gold) to achieve heat dissipation performance comparable to silicon carbide. The multi-material composition allows optimization of both thermal conductivity and cost-effectiveness, replacing expensive SiC with a composite system that leverages the advantages of each material.
Solution Approach 2:
The metal layers serve as intermediary elements between the nitride-based active device and the silicon substrate. These intermediary layers (particularly copper with high thermal conductivity and molybdenum for thermal expansion matching) mediate the thermal transfer, enabling effective heat dissipation from the device through the silicon substrate without requiring expensive SiC.
2Ease of manufacture
If a silicon substrate is used to reduce cost, then manufacturing cost decreases, but heat dissipation capability deteriorates
Solution Approach 1:
The patent employs a composite structure combining silicon substrate with metal layers (copper, molybdenum, gold) to achieve heat dissipation performance comparable to silicon carbide. The multi-material composition allows optimization of both thermal conductivity and cost-effectiveness, replacing expensive SiC with a composite system that leverages the advantages of each material.
Solution Approach 2:
The patent applies local quality enhancement by concentrating high thermal conductivity materials (copper layer) directly at the heat generation point (under the active device), while using other metals for specific functions like thermal expansion matching (molybdenum) and connectivity (gold). This localized optimization ensures effective heat dissipation where needed most while maintaining overall cost efficiency.
3Temperature
If additional arrangements are added to dissipate heat from active devices on silicon substrate, then heat dissipation performance is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the metal layers: thermal conduction (copper), thermal expansion buffering (molybdenum), electrical connectivity (gold), and mechanical support. This consolidation achieves effective heat dissipation without adding separate dedicated heat dissipation components, thereby avoiding increased device complexity while maintaining performance.
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 solution effectively manages heat dissipation from nitride-based active devices on silicon substrates, reducing costs associated with silicon carbide substrates while maintaining high-frequency performance, thereby addressing the thermal conductivity gap.
Implementation Method 1
The metal layer covers the whole back surface and the inner surface of the via hole... at least a portion of the active device comes in directly contact with the metal layer which is exposed in the primary surface of the Si substrate
Data Source
AI summary
A semiconductor device and a process to form the semiconductor device are disclosed. The semiconductor device includes a Si substrate, active devices primarily made of nitride based compound semiconductor material, and passive devices. The Si substrate includes a via hole piercing from the back surface to the primary surface of the Si substrate. The active device is mounted on the primary surface so as to cover at least a portion of the via hole. The metal layer cover the whole back surface, inner surfaces of the via hole, and the back surface of the active device exposed in the via hole.