Carbon Nanotube FET with N-Type End-Bonded Contacts

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Solution Overview

Problem

As CMOS technology scales down, contact resistance in carbon nanotube devices becomes comparable to channel resistance, limiting transistor drive current, and existing technologies lack effective methods for forming n-type end-bonded metal contacts, which are crucial for future sub-10 nm technology nodes.

Innovation Solution

The formation of field effect transistors using carbon nanotubes with end-bonded metal contacts, where a patterned resist layer exposes portions of the carbon nanotubes and gate dielectric, allowing for the deposition of n-type metal contacts that contact both the nanotubes and dielectric, independent of contact length, thereby reducing resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If contact length is scaled down to match channel length scaling, then device integration density is improved, but contact resistance becomes comparable to channel resistance and limits transistor drive current

Engineering Contradiction:

Improvedevice integration densityVSAvoidtransistor drive current

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the doping type parameter of the contact region from conventional to n-type, which fundamentally alters the electrical characteristics at the contact interface. This parameter change enables maintaining low contact resistance even when contact length is scaled down to tens of nanometers, thus resolving the contradiction between high integration density and sufficient drive current.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional contact formation methods are used, then manufacturing process is simple, but n-type end-bonded metal contacts cannot be formed effectively

Engineering Contradiction:

Improvecontact formation processVSAvoidn-type contact formation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent performs preliminary doping of the contact region with n-type dopants before metal contact formation. This preliminary action ensures that the contact region has the appropriate electrical characteristics prior to metal deposition, enabling effective n-type end-bonded metal contacts to be formed using standard manufacturing processes.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a dielectric layer as an intermediary between the substrate and metal contact, which facilitates the formation of n-type end-bonded contacts by providing proper electrical isolation and mechanical support during the contact formation process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10396300B2Carbon nanotube device with N-type end-bonded metal contacts

Publication Date: 2019.08.27 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A field effect transistor includes a substrate and a gate dielectric formed on the substrate. A channel material is formed on the gate dielectric. The channel material includes carbon nanotubes. A patterned resist layer has openings formed therein. The openings expose portions of the gate dielectric and end portions of the channel material under the patterned resist layer. Metal contacts are formed at least within the openings. The metal contacts include a portion that contacts the end portions of the channel material and the portions of the gate dielectric exposed within the openings.