Method for forming superconducting structures

Patent metadata

Field	Value
Publication number	US-10651233-B2
Application number	US-201816107321-A
Country	US
Kind code	B2
Filing date	Aug 21, 2018
Priority date	Aug 21, 2018
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

A superconducting structure includes a first superconducting device having a plurality of first superconducting contact pads disposed on a top side of a first superconducting device, a second superconducting device having a plurality of second superconducting contact pads disposed on a bottom side of a second superconducting device, and a plurality of superconducting bump structures with a given bump structure coupling respective superconducting contact pads of the plurality of first superconducting contact pads and the second plurality of superconducting pads to one another to bond the first superconducting device to the second superconducting device. Each superconducting bump structure includes a first under bump metallization (UBM) layer disposed on the top surface of a given superconducting contact pad, a second UBM layer disposed on the top surface of a given superconducting contact pads, and a superconducting metal layer coupling the first UBM layer to the second UBM layer.

First claim

What is claimed is:

1. A method of forming a superconducting structure, the method comprising:
performing a first cleaning process on a top surface of a plurality of first superconducting contact pads disposed on a top side of a first superconducting device, the first cleaning process comprising an oxygen based plasma process to remove contamination, a hydrofluoric (HF) acid etch to remove oxides, and an argon based sputter process to clean the top surfaces of the plurality of first superconducting contact pads;
depositing a first under bump metallization (UBM) layer on the top surface of each of the plurality of first superconducting contact pads;
depositing a superconducting metal layer on each of the first UBM layers;
performing a second cleaning process on a top surface of each of the superconducting metal layers;
performing a third cleaning process on a top surface of a plurality of second superconducting contact pads disposed on a bottom side of a second superconducting device, the third cleaning process comprising another oxygen based plasma process to remove contamination, another hydrofluoric (HF) acid etch to remove oxides, and another argon based sputter process to clean the top surfaces of the plurality of second superconducting contact pads;
depositing a second UBM layer on the top surface of each of the plurality of second superconducting contact pads; and
performing a bonding process to connect the first superconducting device and the second superconducting device by coupling the superconducting metal layers of the first superconducting device to respective second UBM layers of the second superconducting device.

2. The method of claim 1 , wherein the first and second UBM layers have a thickness between 10 Å to 1000 Å to promote adhesion and to provide similar properties as a superconductor.

3. The method of claim 1 , wherein the first and second UBM layers are formed from one of gold, titanium, chromium, platinum or a combination thereof.

4. The method of claim 1 , wherein the superconducting metal layer is formed from indium.

5. The method of claim 1 , wherein the second cleaning process is one of a hydrochloric (HCl) acid etch, a formic acid etch, or a xenon difluoride (XeF 2 ) etch to remove oxides on the top surface of the superconducting metal layer.

6. The method of claim 1 , further comprising performing a fourth cleaning process on a top surface of each of the second UBM layers.

7. The method of claim 6 , wherein the fourth cleaning process is an oxygen and argon based plasma process to clean the top surface of each of the second UBM layers.

8. The method of claim 7 , wherein the fourth cleaning process is an oxygen and argon based plasma process to clean the top surface of each of the second UBM layers.

9. A method of forming a superconducting structure, the method comprising:
performing a first cleaning process on a top surface of a plurality of first superconducting contact pads disposed on a top side of a first superconducting device, the first cleaning process comprising an oxygen based plasma process to remove contamination, a hydrofluoric (HF) acid etch to remove oxides, and an argon based sputter process to clean the top surfaces of the plurality of first superconducting contact pads;
depositing a first under bump metallization (UBM) layer of gold having a thickness between 10 Å to 1000 Å, to provide similar properties as a superconductor, on the top surface of each of the plurality of first superconducting contact pads;
depositing a superconducting metal layer on each of the first UBM layers;
performing a second cleaning process on a top surface of each of the superconducting metal layers, the third cleaning process comprising another oxygen based plasma process to remove contamination, another hydrofluoric (HF) acid etch to remove oxides, and another argon based sputter process to clean the top surfaces of the plurality of second superconducting contact pads;
performing a third cleaning process on a top surface of a plurality of second superconducting contact pads disposed on a bottom side of a second superconducting device;
depositing a second UBM layer of gold having a thickness between 10 Å to 1000 Å, to provide similar properties as a superconductor, on the top surface of each of the plurality of second superconducting contact pads;
performing a fourth cleaning process on a top surface of each of the second UBM layers; and
performing a bonding process to connect the first superconducting device and the second superconducting device by coupling the superconducting metal layers of the first superconducting device to respective second UBM layers of the second superconducting device.

10. The method of claim 9 , wherein the superconducting metal layer is formed from indium or indium containing alloys.

11. The method of claim 9 , wherein the second cleaning process is one of a hydrochloric (HCl) acid etch, a formic acid etch, or a xenon difluoride (XeF 2 ) etch to remove oxides on the top surface of the superconducting metal layer.

12. The method of claim 9 , wherein the bonding process is a flip chip process.

Assignees

• Hartman Jeffrey David
• Hackley Justin C
• Northrop Grumman Systems Corp

Inventors

• Hartman Jeffrey David
• Hackley Justin C

Classifications

• H01L2224/13144

  Electricity · mapped topic

• H01L39/24

  Electricity · mapped topic

• H01L2224/13171

  Electricity · mapped topic

• H01L24/13

  Electricity · mapped topic

• H01L24/81

  Electricity · mapped topic