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Niobium Etched Edge Slope Soak

IP.com Disclosure Number: IPCOM000045063D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kirk, JP: AUTHOR [+2]

Abstract

This article is directed to a method for chemically controlling the etch profile of the ground plane in a Josephson structure. The method features control of the slope of etched edge in a niobium film ground plane of a Josephson structure by use of a pre-etch soak in trisodium phosphate dodecahydrate, disodium phosphate duohydrate and sodium metasilicate pentahydrate.

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Niobium Etched Edge Slope Soak

This article is directed to a method for chemically controlling the etch profile of the ground plane in a Josephson structure. The method features control of the slope of etched edge in a niobium film ground plane of a Josephson structure by use of a pre-etch soak in trisodium phosphate dodecahydrate, disodium phosphate duohydrate and sodium metasilicate pentahydrate.

The slope of etched edges of niobium films, such as used for a Josephson device ground plane, can be controlled by a surface treatment prior to coating with photoresist. The formulation of the soaking solution used in the treatment is given in Table I. The soak is followed by the application of HMDS and Shipley AZ 1350 resist, exposure, resist development and then a niobium etch. The resulting etched edge slope is then related to the soak time.

Different portions of an etched line can be made to have different slopes without altering the line width at the base of the niobium by controlling the time of the soak at different regions. Table I

Soak Solution

Trisodium phosphate dodecahydrate 2.76%

Disodium phosphate duohydrate 0.09%

Sodium metasilicate pentahydrate 4.72%

DI water 91.06%

Table II

Etch Solution

Hydrofluoric acid, 48% 5.06%

Nitric acid, conc. 33.03%

DI water 61.01%.

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