Aligned Carbon Nanotube Layer System for Microsystem Integration
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Solution Overview
Problem
Current methods for integrating carbon nanotubes (CNTs) into electronic and sensory components face challenges such as limited density, porosity, and variability in CNT length, leading to issues with electrical and thermal contact, and mechanical stabilization, which complicates their use in applications like ULSI circuits, sensors, and actuators.
Innovation Solution
A layer system comprising CNTs aligned parallel to each other with a metallic cover layer, utilizing a catalyst system that includes a structuring material like chromium, which allows for high-density, vertically aligned CNT growth and provides a stable, conductive interface for electrical and thermal contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional CVD methods are used to grow CNTs, then CNTs can be produced with moderate growth temperatures, but the CNT density remains low and porosity is high
Solution Approach 1:
The patent applies a preliminary action by depositing a metallic cover layer on the CNTs before final integration. This cover layer is applied in advance to ensure proper electrical and thermal contact, preventing the porosity and contact quality issues that would otherwise occur with low-density CNT forests grown by conventional CVD methods.
2Reliability
If vertically grown CNTs are embedded with metal for electrical contact, then electrical contact can be established, but interdiffusion of materials occurs due to low density
Solution Approach 1:
The patent introduces an intermediary solution by using a metallic cover layer that is deposited over the CNTs. This cover layer acts as a mediator that provides electrical contact without causing interdiffusion, as it is applied after CNT growth rather than being embedded during growth, thus maintaining material composition stability while ensuring electrical contact reliability.
3Quantity of substance
If CNTs are grown to achieve high filling levels, then porosity is reduced, but mechanical stabilization with additional processing steps is required
Solution Approach 1:
The patent merges multiple functions into a single step by depositing the metallic cover layer. This single deposition step simultaneously provides electrical contact, thermal contact, and mechanical stabilization for the CNTs, eliminating the need for separate mechanical stabilization processing steps while achieving high filling levels.
4Reliability
If CNT length is increased for better performance, then electrical and thermal properties improve, but length uniformity decreases leading to integration problems
Solution Approach 1:
The patent applies local quality by ensuring that the metallic cover layer uniformly coats all CNTs regardless of their length variations. The cover layer is deposited in a manner that provides consistent electrical and thermal contact at the CNT tips, compensating for length non-uniformity and maintaining manufacturing precision while preserving the improved electrical and thermal performance of longer CNTs.
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
This approach enables improved integration of CNTs with enhanced mechanical stability, electrical conductivity, and thermal performance, facilitating the creation of high-density CNT layers suitable for advanced electronic and sensory applications, including ULSI circuits, sensors, and actuators.
Implementation Method 1
A catalytic decomposition of a C-containing precursor takes place on these at temperatures in the range from 300 to 900°C
Implementation Method 2
a cover layer with metallic properties, which is in electrically and thermally conductive contact with the CNTs
Implementation Method 3
a cover layer with metallic properties, which is in electrically and thermally conductive contact with the CNTs
Implementation Method 4
chemical vapor deposition (CVD)
Data Source
Figure 1a~1f
Figure 2a~3
Figure 4~5c
AI summary
The invention relates to a layer system, comprising a layer of carbon nanotubes oriented parallel to one another and a surface layer having metallic properties connected directly thereto, from which surface layer the carbon nanotubes have grown in tip growth. The layer system can also have a base layer and/or a substrate. The layer system can be obtained by producing a structured layer comprising a first phase, which is composed of a metal that has no independent catalytic activity with respect to the production of CNTs from the gas phase, and a second phase, which is composed of a metal that catalyzes the production of CNTs from the gas phase, on a substrate or a base layer, wherein the first phase has a structure that is unevenly thick and/or folded and optionally interspersed with pores and the second phase is located in recesses and/or pores of the first phase in such a way that the two material phases are at least partially adjacent to one another in the lateral plane, on the substrate or the base layer located thereon. Carbon is deposited on said structured layer from a gas atmosphere containing carbon, wherein carbon nanotubes are formed and said carbon nanotubes raise at least parts of the structured layer in a closed form. The substrate or the base layer can subsequently be removed. The layer system of the invention is suitable for use in a large number of components and electronic microsystems and nanosystems, flip-chip connections, sensors or actuators, in particular pressure sensors, contact sensors, optical sensors, mirrors, projectors, optical filters, nanopositioning systems, or interferometers, and, in a specific form, also in a super capacitor.