BEOL Interconnect Structure With Air Gaps for Heat and Capacitance
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Solution Overview
Problem
The challenge of high parasitic capacitance and low thermal conductivity in semiconductor interconnect structures, particularly in back-end-of-line (BEOL) components, hinders the performance of smaller and faster electronic devices, as low-k dielectric materials used to reduce capacitance fail to effectively dissipate heat generated by front-end-of-line (FEOL) devices.
Innovation Solution
A dielectric structure is formed between adjacent metal lines, comprising air gaps created by removing a sacrificial layer and filling trenches with high-kappa non-conductive materials to enhance thermal conductivity while maintaining low parasitic capacitance, using a method that includes patterning metal layers, depositing sacrificial and sustaining layers, and applying high-kappa materials for efficient heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If low-k dielectric materials are used to reduce parasitic capacitance, then parasitic capacitance is reduced, but thermal conductivity deteriorates
Solution Approach 1:
The patent employs a composite dielectric structure combining low-k material (for low parasitic capacitance) with high-kappa non-conductive material (for high thermal conductivity). This composite approach allows the structure to simultaneously achieve low parasitic capacitance through the low-k material while maintaining high thermal conductivity through the high-kappa material layer, directly resolving the contradiction between these two opposing requirements.
2Productivity
If device dimensions are scaled down to improve production efficiency and lower costs, then production efficiency is improved and costs are reduced, but manufacturing complexity increases
Solution Approach 1:
The dielectric structure is segmented into multiple functional layers: a low-k dielectric material layer for capacitance reduction, a high-kappa non-conductive material layer for thermal conductivity enhancement, and air gaps for additional capacitance reduction. This segmentation allows each layer to independently address specific requirements, enabling scaled-down device dimensions while managing the increased manufacturing complexity through modular construction.
3Length of moving object
If distance between adjacent conductive features is reduced to meet design requirements, then device miniaturization is achieved, but parasitic capacitance increases
Solution Approach 1:
The patent introduces air gaps as intermediary structures between adjacent conductive features. These air gaps, formed by removing sacrificial layers, serve as mediators that electrically isolate the conductive features while maintaining minimal physical distance. The air gaps have very low dielectric constant, effectively reducing parasitic capacitance between closely-spaced features without requiring increased separation distance.
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 reduces parasitic capacitance and enhances thermal conductivity, improving the performance and efficiency of semiconductor devices by allowing for better heat dissipation and maintaining low capacitance levels.
Implementation Method 1
air gaps created by removing a sacrificial layer and filling trenches with high-kappa non-conductive materials to enhance thermal conductivity while maintaining low parasitic capacitance
Implementation Method 2
high-kappa non-conductive materials to enhance thermal conductivity while maintaining low parasitic capacitance
Data Source
AI summary
Semiconductor structures and methods of forming the same are provided. An exemplary semiconductor structure includes a conductive via embedded in a first dielectric layer, a second dielectric layer over the first dielectric layer, a first metal line embedded in the second dielectric layer and in electrical coupling with the conductive via, and a second metal line embedded in the second dielectric layer and separated from the first metal line by a dielectric structure. A top surface of the dielectric structure is coplanar with top surfaces of the first and second metal lines. The dielectric structure includes a capping layer extending between opposing sidewalls of the first and second metal lines, a thermal conductive layer over the capping layer, and an air gap between the capping layer and the thermal conductive layer.