Carbon Nanotube Interconnects for Semiconductor Current Density
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Solution Overview
Problem
Conventional metal interconnect structures, such as those using aluminum and copper, face challenges in miniaturized semiconductor devices due to increased electrical current, surface scattering, and reduced reliability, necessitating a novel material with high thermal conductivity and mechanical strength.
Innovation Solution
The method involves forming carbon nanotube bundles perpendicular to a substrate within a semiconductor structure, using a sacrificial layer and catalyst layer, and sealing them with dielectric material to enhance reliability and current carrying capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Cu interconnect technique is used to substitute Al interconnect technique, then the electrical current carrying capacity is improved, but the resistance increases due to surface scattering and crystal boundary scattering
Solution Approach 1:
The patent changes the material parameter from conventional metals (Al, Cu) to carbon nanotubes, which have fundamentally different electrical transport properties. Carbon nanotubes exhibit ballistic transport with minimal scattering, achieving both high current carrying capacity and low resistance simultaneously, thus resolving the contradiction between current capacity and reliability.
Solution Approach 2:
The patent uses composite structures combining carbon nanotubes with metal layers (such as Cu or Al) to create hybrid interconnect systems. The carbon nanotube core provides high current carrying capacity and low resistance, while the metal cladding layers provide mechanical strength and integration compatibility, thereby achieving both improved reliability and current capacity.
2Area of moving object
If feature size is miniaturized, then the circuit density is increased, but the resistance of Cu interconnect lines increases due to increased surface scattering
Solution Approach 1:
The patent changes the material parameters by introducing carbon nanotubes with unique quantum transport properties. At nanoscale dimensions, carbon nanotubes maintain low resistance through ballistic electron transport, unlike conventional metals where surface scattering dominates at small feature sizes. This enables high circuit density without the resistance penalty that plagues miniaturized Cu interconnects.
3Ease of manufacture
If conventional Al interconnect structures are used, then the manufacturing process is simple, but the response time cannot meet the requirements of high-speed circuits
Solution Approach 1:
The patent changes the material from aluminum to carbon nanotubes, exploiting the fundamentally different electrical transport mechanisms. Carbon nanotubes exhibit ballistic transport with mean free paths much longer than conventional metals, enabling significantly faster electron transit times and lower RC delays, thus meeting high-speed circuit requirements while maintaining compatibility with existing semiconductor manufacturing processes.
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 carbon nanotube interconnect structure improves reliability and current density by minimizing scattering effects and maintaining mechanical integrity, addressing the limitations of copper interconnects in miniaturized semiconductor devices.
Implementation Method 1
forming a catalyst layer on the exposed portion of the surface of the first conductive layer and a top surface of the sacrificial layer. Further, the method includes forming a carbon nanotube bundle perpendicular to the surface of the substrate on the catalyst layer
Implementation Method 2
the transport mode of the carriers in a carbon nanotube is a ballistic transport mode, the transport of the carriers in the carbon nanotube may barely be affected by the scattering effect
Implementation Method 3
Carbon nanotubes have a significantly high thermal conductivity. Thus, they favor the dissipation of heat
Implementation Method 4
forming a first dielectric material layer covering a top surface of the carbon nanotube bundle formed within the opening and a portion the surface of the substrate without carbon nanotubes to seal the carbon nanotube bundles in a space
Data Source
AI summary
A method is provided for fabricating an interconnect structure. The method includes providing a substrate; and forming a first conductive layer; and forming a sacrificial layer on the substrate and the first conductive layer. The method also includes forming an opening exposing a surface of the first conductive layer in the sacrificial layer; and forming a catalyst layer on the exposed portion of the surface of the first conductive layer and a top surface of the sacrificial layer. Further, the method includes forming carbon nanotube bundles perpendicular to the surface of the substrate on the catalyst layer; and removing the sacrificial layer and the carbon bundles on the sacrificial layer. Further, the method also includes forming a first dielectric material layer covering top surfaces of the carbon nanotube bundles and a portion the surface of the substrate without carbon nanotubes to seal the carbon nanotube bundles in a space.