Capacitive Heat Shield Isolation for Electromigration
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Solution Overview
Problem
Integrated circuit metal lines are susceptible to current-driven electromigration, leading to failures such as voids and short circuits due to metal redistribution, which existing technologies have not adequately addressed for high-performance heat management.
Innovation Solution
A silicon-on-insulator substrate with a trench isolation region, contact plug, and interconnect structure including a heat shield capacitively isolated from the handle wafer, which reduces thermal conductivity and parasitic capacitance while enhancing heat dissipation and electromigration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat shield is directly connected to the handle wafer, then heat dissipation is improved, but parasitic capacitance increases and thermal resistance decreases
Solution Approach 1:
The connection between the heat shield and handle wafer is segmented into multiple parts: the heat shield, an isolation structure (capacitive isolator), and the handle wafer. This segmentation allows the heat shield to dissipate heat while the isolation structure blocks direct electrical connection, reducing parasitic capacitance and preventing electromigration pathways.
Solution Approach 2:
An isolation structure acts as an intermediary element between the heat shield and the handle wafer. This intermediary provides capacitive isolation that reduces parasitic capacitance while still allowing thermal management functionality, thereby improving electromigration resistance without completely sacrificing heat dissipation capability.
2Temperature
If thermal conductivity is increased to improve heat dissipation, then temperature control is improved, but parasitic capacitance increases
Solution Approach 1:
The isolation structure provides localized capacitive isolation at the interface between the heat shield and handle wafer. This local application of isolation properties allows the rest of the system to maintain good thermal conductivity for heat dissipation while specifically addressing the parasitic capacitance issue at the critical connection point.
Solution Approach 2:
The system uses a composite structure combining the heat shield (for thermal management) with an isolation structure layer (for electrical isolation). This composite approach allows simultaneous achievement of heat dissipation and parasitic capacitance reduction by combining materials and structures with different functional properties.
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 limits temperature rise in metal lines, reducing electromigration-induced failures and improving circuit reliability by using a heat shield that dissipates heat to the handle wafer without compromising thermal resistance.
Implementation Method 1
The isolation structure capacitively isolates the heat shield from the handle wafer
Implementation Method 2
a heat shield that dissipates heat to the handle wafer without compromising thermal resistance
Data Source
AI summary
Methods and structures for capacitively isolating a heat shield from a handle wafer of a silicon-on-insulator substrate. A contact plug is located in a trench extending through a trench isolation region in a device layer of the silicon-on-insulator substrate and at least partially through a buried insulator layer of the silicon-on-insulator substrate. The heat shield is located in an interconnect structure, which also includes a wire coupling the heat shield with the contact plug. An isolation structure is positioned between the contact plug and a portion of the handle wafer. The isolation structure provides the capacitive isolation.