Patterned Wafer Surface Charge for Carbon Nanotube Alignment

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Solution Overview

Problem

Existing methods for placing carbon nanotubes on substrates often result in random placement, orientation, or bundling, leading to variability in the number of carbon nanotubes in a single transistor and difficulties in achieving a highly ordered arrangement.

Innovation Solution

The use of wafers with alternating areas of different surface charges, where alignment areas with a specific polarity and spacing areas with a different polarity are arranged to guide the alignment of carbon nanotubes, reducing bundling and allowing for precise control over the distance between individual nanotubes through lithographic definition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional methods are used to place carbon nanotubes on substrates, then the process is simple and fast, but the placement is random and bundling occurs

Engineering Contradiction:

Improvenanotube placement precisionVSAvoidwafer structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The wafer surface is segmented into alternating first areas and second areas with different surface charges. This segmentation creates distinct zones that guide nanotube placement, preventing random distribution and bundling by providing specific alignment regions separated by spacing regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different areas of the wafer surface are given different local properties through varying surface charges. The first areas have one surface charge polarity while the second areas have the opposite polarity, creating local quality differences that direct nanotube alignment and placement precision.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If alternating areas with different surface charges are used, then nanotube alignment is improved, but the wafer manufacturing process becomes more complex

Engineering Contradiction:

Improvenanotube alignment precisionVSAvoidwafer manufacturing ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The alternating first and second areas with different surface charges are prepared in advance on the wafer surface before nanotube placement. This preliminary structuring of the substrate creates pre-defined alignment zones that guide nanotube positioning, eliminating the need for complex real-time alignment procedures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The alternating charged areas act as an intermediary structure between the nanotubes and the substrate. This intermediate patterned surface charge distribution mediates the interaction between nanotubes and the substrate, providing electrostatic guidance for precise alignment while keeping the actual nanotube placement process relatively simple.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If random placement is used, then the process is simple, but variability in transistor formation increases

Engineering Contradiction:

Improvetransistor formation reliabilityVSAvoidalignment structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The alternating first and second areas create regions of different electrostatic potential that guide nanotube placement. By establishing these equipotential zones with opposite surface charge polarities, the system provides consistent electrostatic forces that reliably guide nanotube alignment, reducing variability in transistor formation.

Inventive Principle:

Principle #12Equipotentiality

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 produces a highly ordered arrangement of carbon nanotubes, reducing variability in transistor formation and enabling precise control over the carbon nanotube pitch, which enhances the reliability and performance of carbon nanotube-based devices.

Implementation Method 1

wafers with alternating areas of different surface charges, where alignment areas with a specific polarity and spacing areas with a different polarity are arranged to guide the alignment of carbon nanotubes

Methodology Applied

Scientific EffectElectrostatic interaction: Electrostatics

Data Source

PatentUS11557726B2Wafers for use in aligning nanotubes and methods of making and using the same

Publication Date: 2023.01.17 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Provided herein are wafers that can be used to align carbon nanotubes, as well as methods of making and using the same. Such wafers include alignment areas that have four sides and a surface charge, where the alignment areas are surrounded by areas that have a surface charge of a different polarity. Methods of the disclosure may include depositing and selectively etching a number of hardmasks on a substrate. The described methods may also include depositing a carbon nanotube on such a wafer.