# US 10,312,142 B2 · Method of forming superconductor structures

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- Number: US 10,312,142 B2
- Document ID: US10312142B2
- Status: Granted
- Kind: B2
- Application number: 15/362,400
- Filed: 2016-11-28
- Published: 2018-05-31
- Granted: 2019-06-04
- Earliest claimed: 2016-11-28
- Assignees: Northrop Grumman Systems Corporation
- Applicants: Christopher F. Kirby; Michael Rennie; Daniel J. O'Donnell; Sandro J. Di Giacomo
- Inventors: Christopher F. Kirby; Michael Rennie; Daniel J. O'Donnell; Sandro J. Di Giacomo
- Web page: https://patentgrep.com/patent/US10312142B2

## CPC

- H10W 20/064: {by modifying the conductivity of conductive parts, e.g. by alloying}
- H01P 3/081: {Microstriplines}
- H01P 11/003: {Manufacturing lines with conductors on a substrate, e.g. strip lines, slot lines}
- H10N 60/0156: {of devices comprising Nb or an alloy of Nb with one or more of the elements of group IVB, e.g. titanium, zirconium or hafnium}
- H10N 60/85: Superconducting active materials
- H10P 50/283: {by chemical means}
- H10P 52/403: {of conductive or resistive materials}
- H10P 70/234: {the processing being the formation of vias or contact holes}
- H10P 70/277: {the processing being a planarisation of conductive layers}
- H10P 76/204: {of organic photoresist masks}
- H10W 20/037: {the barrier, adhesion or liner layers being on top of a main fill metal}
- H10W 20/038: {covering conductive structures (H10W20/037 takes precedence)}
- H10W 20/056: {by filling conductive material into holes, grooves or trenches}
- H10W 20/062: {by smoothing of conductive parts, e.g. by planarisation}
- H10W 20/081: {by forming openings in the dielectric parts}
- H10W 20/42: Vias, e.g. via plugs
- H10W 20/43: Layouts of interconnections
- H10W 20/4484: {Superconducting materials}
- H10W 44/20: at high-frequency [HF] or radio frequency [RF]
- H10W 20/084: {for dual-damascene structures}
- H10W 44/216: {Waveguides, e.g. strip lines}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H01P: WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE (operating at optical frequencies G02B)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method of forming a superconductor structure is provided. The method comprises forming a superconducting element in a first dielectric layer that has a top surface aligned with the top surface of the first dielectric layer, forming a second dielectric layer over the first dielectric layer and the superconducting element, and forming an opening in the second dielectric layer to a top surface of the superconducting element. The method also comprises performing a cleaning process on the top surface of the superconducting element to remove oxides formed on the top surface of the superconducting element at a first processing stage, forming a protective barrier over the top surface of the superconducting element, and moving the superconductor structure to a second processing stage for further processing.

## Claims

### Claim 1

A method of forming a superconductor structure, the method comprising:
forming a superconducting element in a first dielectric layer, the superconducting element having a top surface aligned with a top surface of the first dielectric layer;
forming a second dielectric layer over the first dielectric layer and the superconducting element, the second dielectric layer being in contact with the top surface of the first dielectric layer and with the top surface of the superconducting element;
forming an opening in the second dielectric layer to the top surface of the superconducting element;
performing a cleaning process on the top surface of the superconducting element to remove oxides formed on the top surface of the superconducting element at a first processing stage;
forming a protective barrier over the top surface of the superconducting element; and
moving the superconductor structure to a second processing stage for further processing.

### Claim 2 (depends on 1)

The method of claim 1, wherein the cleaning process is a fluorine based reactive clean process.

### Claim 3 (depends on 1)

The method of claim 1, wherein the superconducting element is formed from niobium and the protective barrier is formed from niobium nitride.

### Claim 4 (depends on 1)

The method of claim 1, wherein the forming the superconducting element that has a top surface aligned with the top surface of the first dielectric layer comprises:
forming a patterned photoresist layer with an opening overlying the first dielectric layer;
etching the first dielectric layer to form an extended opening in the first dielectric layer based on the opening in the photoresist layer;
stripping the photoresist layer;
performing a wet etch to remove oxide on the first dielectric layer caused by the stripping of the photoresist layer;
performing a contact material fill to fill the extended opening; and
performing a chemical mechanical polish (CMP) to align a top surface of the superconducting element with a top surface of the first dielectric layer, wherein the cleaning process removes oxidization on a top surface of the superconducting element and the top surface of the first dielectric layer both caused by at least the CMP.

### Claim 5 (depends on 4)

The method of claim 4, wherein the forming an opening comprises:
forming a second patterned photoresist layer with a via pattern opening overlying the second dielectric layer and aligned with the superconducting element;
etching the second dielectric layer to form the extended opening in the second dielectric layer to the superconducting element based on the via pattern opening in the second photoresist layer; and
stripping the second photoresist layer.

### Claim 6 (depends on 5)

The method of claim 5, further comprising:
forming a third patterned photoresist layer with a trench opening pattern overlying and surrounding the extended opening in the second dielectric layer and aligned with the superconducting element;
partially etching the second dielectric layer to form a trench opening in the second dielectric layer based on the trench opening pattern in the third photoresist layer; and
stripping the third photoresist layer.

### Claim 7 (depends on 6)

The method of claim 6, further comprising performing a cleaning process to remove oxides formed on a top surface of the second dielectric layer and the top surface of the superconducting element due to at least the stripping of the third photoresist layer prior to the forming a protective barrier over the top surface of the superconducting element.

### Claim 8 (depends on 7)

The method of claim 7, further comprising:
performing an argon sputter clean to remove the protective barrier:
performing a superconducting contact material fill to fill the extended opening and the trench opening;
performing a chemical mechanical polish (CMP) to align a top surface of the superconducting element with a top surface of the second dielectric layer to form a superconductive line;
performing a cleaning process to remove oxides formed on a top surface of the second dielectric layer and the top surface of the superconductive line; and
forming a protective barrier on a top surface of the superconductive line to protect the superconductive line from further oxidization when being moved to a subsequent stage for further processing.

### Claim 9 (depends on 1)

The method of claim 1, wherein at least one of the dielectric material employed in the first dielectric layer and the second dielectric layer is formed of a dielectric material that can form at a temperature of about or below 160° Celsius.

### Claim 10

A method of forming a superconductor structure, the method comprising:
forming a first opening in a first dielectric layer overlying a substrate;
performing a wet etch to remove oxides from the first dielectric layer caused by the forming of the first opening;
forming a first superconductive line in the first opening having a top surface aligned with a top surface of the first dielectric layer;
performing a first cleaning process on the top surface of the first superconductive line and the top surface of the first dielectric layer to remove oxides from the top surface of the first superconductive line and the top surface of the first dielectric layer;
forming a second dielectric layer over the first dielectric layer and the first superconductive line;
forming a via opening in the second dielectric layer to a top surface of the superconductive line, and a trench opening surrounding the via opening and partially extending into the second dielectric layer;
performing a second cleaning process on the top surface of the first superconductive line to remove oxides formed on the top surface of the first superconductive line and the remaining portions of the superconductor structure;
forming a protective barrier over the top surface of the first superconductive line at a first processing stage to mitigate oxide formation over the top surface of the superconductive line;
moving the superconductor structure to a second processing stage for further processing;
removing the protective barrier;
forming a contact in the via opening and a second conductive line in the trench opening.

### Claim 11 (depends on 10)

The method of claim 10, wherein the first and the second cleaning processes are a reactive fluorine based cleaning process.

### Claim 12 (depends on 10)

The method of claim 10, wherein the first superconductive line, the contact and the second superconductive line are formed from niobium.

### Claim 13 (depends on 10)

The method of claim 10, wherein the protective barrier is formed from niobium nitride.

### Claim 14 (depends on 10)

The method of claim 10, wherein the removing the protective barrier comprises performing an argon sputter clean to remove the protective barrier.

### Claim 15 (depends on 10)

The method of claim 10, further comprising performing a third cleaning process on the top surface of the second superconductive line to remove oxides formed on the top surface of the second superconductive line, and forming a protective barrier over the top surface of the second superconductive line to mitigate oxide formation over the top surface of the second superconductive line at a subsequent processing stage.

### Claim 16 (depends on 10)

The method of claim 10, wherein at least one of the dielectric material employed in the first dielectric layer and the second dielectric layer is formed of a dielectric material that can form at a temperature of about or below 160° Celsius.

### Claim 17

A method of forming a superconductor interconnect structure, the method comprising:
forming a first dielectric layer overlying a substrate
forming a patterned photoresist layer with an opening overlying the first dielectric layer;
etching the first dielectric layer to form an extended opening in the first dielectric layer based on the opening in the photoresist layer;
stripping the photoresist layer;
performing a wet etch to remove the oxide layer on the first dielectric layer caused by the stripping of the photoresist layer;
performing a contact material fill to fill the extended opening and form a first superconductive line;
performing a chemical mechanical polish (CMP) to align a top surface of the first superconductive line with a top surface of the first dielectric layer;
performing a first cleaning process on the top surface of the first superconductive line and the first dielectric layer to remove oxides formed on the top surface of the first superconductive line and the top surface of the first dielectric layer;
forming a second dielectric layer over the first dielectric layer and the first superconductive line;
forming a via opening in the second dielectric layer to a top surface of the first superconductive line, and a trench opening surrounding the via opening and partially extended into the second dielectric layer;
performing a second cleaning process on the top surface of the first superconductive line to remove oxides formed on the top surface of the first superconductive line during the forming of the via opening and trench opening;
forming a first protective barrier over the top surface of the superconducting element;
moving the superconductor structure to a subsequent stage for further processing;
performing an argon sputter clean to remove the protective barrier;
performing a superconducting contact material fill to fill the via opening and the trench opening to form a contact in the via opening and a second superconductive line in the trench opening;
performing a chemical mechanical polish (CMP) to align a top surface of the second superconductive line with a top surface of the second dielectric layer;
performing a third cleaning process to remove oxides formed on a top surface of the second dielectric layer and the top surface of the second superconductive line; and
forming a second protective barrier on the top surface of the second superconductive line to protect the second superconductive line from further oxidization when being moved to a subsequent stage for further processing.

### Claim 18 (depends on 17)

The method of claim 17, wherein the first, second and third cleaning processes are a reactive fluorine based cleaning process.

### Claim 19 (depends on 17)

The method of claim 17, wherein the first and second superconductive line and the first contact are formed from niobium and the first protective barrier and the second protective barrier are formed from niobium nitride.

### Claim 20 (depends on 17)

The method of claim 17, wherein at least one of the dielectric material employed in the first dielectric layer and the second dielectric layer is formed of a dielectric material that can form at a temperature of about or below 160° Celsius.