# US 10,374,179 B2 · Placement of carbon nanotube guided by DSA patterning

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- Number: US 10,374,179 B2
- Document ID: US10374179B2
- Status: Granted
- Kind: B2
- Application number: 16/247,326
- Filed: 2019-01-14
- Published: 2019-05-30
- Granted: 2019-08-06
- Earliest claimed: 2017-03-16
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Ali Afzali-Ardakani; Sarunya Bangsaruntip; Shu-Jen Han; HsinYu Tsai
- Web page: https://patentgrep.com/patent/US10374179B2

## CPC

- H10K 10/484: {characterised by the channel regions}
- H10K 10/466: {Lateral bottom-gate IGFETs comprising only a single gate}
- H10K 71/12: using liquid deposition, e.g. spin coating
- H10K 71/191: {characterised by provisions for the orientation or alignment of the layer to be deposited}
- H10K 85/225: {comprising substituents}
- H10K 85/761: {Biomolecules or bio-macromolecules, e.g. proteins, chlorophyl, lipids or enzymes}
- H10K 2102/00: Constructional details relating to the organic devices covered by this subclass
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

In one aspect, a method for placing carbon nanotubes on a dielectric includes: using DSA of a block copolymer to create a pattern in the placement guide layer on the dielectric which includes multiple trenches in the placement guide layer, wherein there is a first charge on sidewall and top surfaces of the trenches and a second charge on bottom surfaces of the trenches, and wherein the first charge is different from the second charge; and depositing a carbon nanotube solution onto the dielectric, wherein self-assembly of the deposited carbon nanotubes within the trenches occurs based on i) attractive forces between the first charge on the surfaces of the carbon nanotubes and the second charge on the bottom surfaces of the trenches and ii) repulsive forces between the first charge on the surfaces of the carbon nanotubes and the first charge on sidewall and top surfaces of the trenches.

## Claims

### Claim 1

A method for placing carbon nanotubes on a dielectric, the method comprising the steps of:
forming a placement guide layer on the dielectric;
using directed self-assembly (DSA) of a block copolymer to create a pattern in the placement guide layer, wherein the pattern comprises multiple trenches in the placement guide layer, wherein there is a first charge on sidewall and top surfaces of the trenches and a second charge on bottom surfaces of the trenches, and wherein the first charge is different from the second charge; and
depositing a solution containing the carbon nanotubes onto the dielectric, wherein the carbon nanotubes are functionalized to have the first charge on surfaces thereof, and wherein self-assembly of the deposited carbon nanotubes within the trenches occurs based on i) attractive forces between the first charge on the surfaces of the carbon nanotubes and the second charge on the bottom surfaces of the trenches and ii) repulsive forces between the first charge on the surfaces of the carbon nanotubes and the first charge on sidewall and top surfaces of the trenches.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first charge is a negative charge, and wherein the second charge is a positive charge.

### Claim 3 (depends on 1)

The method of claim 1, wherein the dielectric comprises hafnium oxide.

### Claim 4 (depends on 3)

The method of claim 3, wherein the carbon nanotubes are placed directly on the dielectric.

### Claim 5 (depends on 3)

The method of claim 3, further comprising the step of:
depositing a surface monolayer of 4-(N-hydroxycarboxamido)-1-mehtylpyridinium iodide (NMPI) on the dielectric to functionalize the dielectric with the second charge, wherein the carbon nanotubes are placed on the surface monolayer of the NMPI.

### Claim 6 (depends on 1)

The method of claim 1, wherein the dielectric is disposed on a semiconductor substrate.

### Claim 7 (depends on 1)

The method of claim 1, wherein the carbon nanotubes are functionalized with sodium dodecyl sulphate (SDS).

### Claim 8 (depends on 1)

The method of claim 1, wherein the carbon nanotubes are functionalized with deoxyribonucleic acid (DNA).

### Claim 9 (depends on 1)

The method of claim 1, wherein the placement guide layer comprises poly-silicon or silicon oxide.

### Claim 10 (depends on 9)

The method of claim 9, further comprising the step of:
forming an oxide shell on the sidewall and top surfaces of the trenches.

### Claim 11 (depends on 1)

The method of claim 1, wherein the step of using directed self-assembly of the block copolymer to create the surface pattern on the substrate comprises the steps of:
forming a neutral layer on the placement guide layer;
forming a DSA template on the neutral layer;
forming the block copolymer onto the neutral layer within the DSA template;
patterning the block copolymer to form a pattern in the block copolymer; and
transferring the pattern from the block copolymer to the placement guide layer.

### Claim 12 (depends on 11)

The method of claim 11, wherein the step of forming the DSA template on the neutral layer comprises the steps of:
depositing a DSA template resist material on the neutral layer; and
patterning the DSA template resist material to form the DSA template.

### Claim 13 (depends on 12)

The method of claim 12, wherein the DSA template resist material comprises an electron-beam lithography resist material, a 193i resist material, or hydrogen silsesquioxane (HSQ).

### Claim 14 (depends on 11)

The method of claim 11, wherein the block copolymer comprises poly(styrene-block-methyl methacrylate) (PS-b-PMMA).

### Claim 15 (depends on 1)

The method of claim 1, wherein the first charge is a positive charge, and wherein the second charge is a negative charge.

### Claim 16

A method of forming a carbon nanotube-based field effect transistor (FET) device, the method comprising the steps of:
providing a semiconductor substrate;
disposing a dielectric on the semiconductor substrate;
forming a placement guide layer on the dielectric;
using DSA of a block copolymer to create a pattern in the placement guide layer, wherein the pattern comprises multiple trenches in the placement guide layer, wherein there is a first charge on sidewall and top surfaces of the trenches and a second charge on bottom surfaces of the trenches, and wherein the first charge is different from the second charge;
depositing a solution containing carbon nanotubes onto the substrate, wherein the carbon nanotubes are functionalized to have the first charge on surfaces thereof, and wherein self-assembly of the deposited carbon nanotubes within the trenches occurs based on i) attractive forces between the first charge on the surfaces of the carbon nanotubes and the second charge on the bottom surfaces of the trenches and ii) repulsive forces between the first charge on the surfaces of the carbon nanotubes and the first charge on sidewall and top surfaces of the trenches;
removing the placement guide layer; and
forming metal source and drain contacts to the carbon nanotubes.

### Claim 17 (depends on 16)

The method of claim 16, wherein the semiconductor substrate is doped and serves as a back gate of the carbon nanotube-based FET device.

### Claim 18 (depends on 16)

The method of claim 16, wherein the first charge is a negative charge, and wherein the second charge is a positive charge.

### Claim 19 (depends on 16)

The method of claim 16, wherein the carbon nanotubes are functionalized with SDS.

### Claim 20 (depends on 16)

The method of claim 16, wherein the carbon nanotubes are functionalized with DNA.