RHEA (resist-hardened etch and anodization) process for fine-geometry Josephson junction fabrication

Lee, L.P.S.; Arambula, E.R.; Hanaya, G.; Dang, C.; Sandell, R.; Chan, H.

doi:10.1109/20.133875

Cited by 16 publications

(5 citation statements)

References 6 publications

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“…While a precise and reproducible definition of the JJ size is routinely performed with the help of electron-beam lithography, the application of anodic oxidation in such processes remains a challenge. This is due to the fact that the Nb 2 O 5 layer formed during the anodic oxidation creeps under the resist mask protecting the top electrode of the JJ (this is known as 'encroachment' [1,2]). Even for a plasma hardened resist and an anodization voltage of 20 V, a significant encroachment was still observed [1].…”

Section: Introductionmentioning

confidence: 99%

“…This is due to the fact that the Nb 2 O 5 layer formed during the anodic oxidation creeps under the resist mask protecting the top electrode of the JJ (this is known as 'encroachment' [1,2]). Even for a plasma hardened resist and an anodization voltage of 20 V, a significant encroachment was still observed [1]. Some groups solve this problem by simply omitting the anodic oxidation or performing it at very low voltages below 10 V [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Aluminum hard mask technique for the fabrication of high quality submicron Nb/Al–AlO_x/Nb Josephson junctions

Kaiser¹,

Meckbach²,

Ilin³

et al. 2010

Supercond. Sci. Technol.

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We have developed a combined photolithography and electron-beam lithography fabrication process for sub-μm to μm-size Nb/Al-AlO x /Nb Josephson junctions. In order to define the junction size and protect its top electrode during anodic oxidation, we developed and used the new concept of an aluminum hard mask. Josephson junctions of sizes down to 0.5 μm 2 have been fabricated and thoroughly characterized. We found that they have a very high quality, which is witnessed by the I V curves with quality parameters V m > 50 mV and V gap = 2.8 mV at 4.2 K, as well as I c R N products of 1.75-1.93 mV obtained at lower temperatures. In order to test the usability of our fabrication process for superconducting quantum bits, we have also designed, fabricated and experimentally investigated phase qubits made of these junctions. We found a relaxation time of T 1 = 26 ns and a dephasing time of T 2 = 21 ns.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aluminum hard mask technique for the fabrication of high quality submicron Nb/Al–AlO_x/Nb Josephson junctions

Kaiser¹,

Meckbach²,

Ilin³

et al. 2010

Supercond. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…This is due to the fact that the Nb 2 O 5 layer formed during the anodic oxidation creeps under the resist mask protecting the top electrode of the JJ (this is known as "encroachment" [1,2]). Even for a plasma hardened resist and an anodization voltage of 20 V, a significant encroachment was still observed [1]. Some groups solve this problem by simply omitting the anodic oxidation or performing it at very low voltages below 10 V [3,4,5,6].…”

Section: Introductionmentioning

confidence: 99%

Aluminum Hard Mask Technique for the Fabrication of High-Quality Submicron Nb/Al-AlOx/Nb Josephson Junctions

Kaiser,

Meckbach,

Ilin

et al. 2010

Preprint

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We have developed a combined photolithography and electron-beam lithography fabrication process for sub-µm to µm-size Nb/Al-AlO x /Nb Josephson junctions. In order to define the junction size and protect its top electrode during anodic oxidation, we developed and used the new concept of an aluminum hard mask. Josephson junctions of sizes down to 0.5 µm 2 have been fabricated and thoroughly characterized. We found that they have a very high quality, which is witnessed by the IV curves with quality parameters V m > 50 mV and V gap = 2.8 mV at 4.2 K, as well as I c R N products of 1.75 − 1.93 mV obtained at lower temperatures. In order to test the usability of our fabrication process for superconducting quantum bits, we have also designed, fabricated and experimentally investigated phase qubits made of these junctions. We found a relaxation time of T 1 = 26 ns and a dephasing time of T 2 = 21 ns.

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“…It used thick anodized Nb O layer as a dry-etching stop to fabricate submicron junctions. Another modified SNAP is "Resist-Hardened Etch and Anodization" (RHEA) which reduced the anodized Nb O thickness [9]. Some submicron junctions were fabricated using SCAN and RHEA.…”

Section: Introductionmentioning

confidence: 99%

Light-anodization process for high-J/sub c/ micron and submicron superconducting junction and integrated circuit fabrication

Meng

Duzer

2003

IEEE Trans. Appl. Supercond.

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We have developed a new approach for high critical current density ( ) small junction fabrication. The key step is light anodization that forms a thin double-layer of Al 2 O 3 Nb 2 O 5 oxides around the junction area and on the sidewalls of the junction. This anodization ring is a good dry-etch stop, so the via for the junction contact can be larger than the junction area. The anodization ring can also protect the junction from plasma damage during dry etching and sputtering steps; therefore, it can reduce the junction leakage current and critical-current spread. The new technique is very simple and cost effective compared with the CMP approach. It needs only one additional mask and process step. We have used the technique to fabricate high-submicron Nb/Al-AlO /Nb tunnel junctions with very low critical-current spreads. Using this technique, we have also fabricated Nb SQUID's and various Nb digital IC's.

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RHEA (resist-hardened etch and anodization) process for fine-geometry Josephson junction fabrication

Cited by 16 publications

References 6 publications

Aluminum hard mask technique for the fabrication of high quality submicron Nb/Al–AlO_x/Nb Josephson junctions

Aluminum hard mask technique for the fabrication of high quality submicron Nb/Al–AlO_x/Nb Josephson junctions

Aluminum Hard Mask Technique for the Fabrication of High-Quality Submicron Nb/Al-AlOx/Nb Josephson Junctions

Light-anodization process for high-J/sub c/ micron and submicron superconducting junction and integrated circuit fabrication

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RHEA (resist-hardened etch and anodization) process for fine-geometry Josephson junction fabrication

Cited by 16 publications

References 6 publications

Aluminum hard mask technique for the fabrication of high quality submicron Nb/Al–AlOx/Nb Josephson junctions

Aluminum hard mask technique for the fabrication of high quality submicron Nb/Al–AlOx/Nb Josephson junctions

Aluminum Hard Mask Technique for the Fabrication of High-Quality Submicron Nb/Al-AlOx/Nb Josephson Junctions

Light-anodization process for high-J/sub c/ micron and submicron superconducting junction and integrated circuit fabrication

Contact Info

Product

Resources

About

Aluminum hard mask technique for the fabrication of high quality submicron Nb/Al–AlO_x/Nb Josephson junctions

Aluminum hard mask technique for the fabrication of high quality submicron Nb/Al–AlO_x/Nb Josephson junctions