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Resistless Patterning of Refractory Films

IP.com Disclosure Number: IPCOM000036022D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+3]

Abstract

One of the common problems in the patterning of the high temperature superconductor (e.g., YBa1Cu2O3) is that it requires elevated substrate temperatures. To obtain a high transition temperature and a sharp resistive transition, the film is typically deposited on MgO substrates heated to 500oC. Conventional lithographic techniques using resists are not compatible with this requirement. A method is described for preparing MgO substrates to facilitate patterning of the substrate prior to the deposition. This method is particularly suitable for first-level metal deposition and provides planarization for subsequent processing. Further, the process does not involve the use of any chemical that is likely to degrade the intrinsic properties of the film.

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Resistless Patterning of Refractory Films

One of the common problems in the patterning of the high temperature superconductor (e.g., YBa1Cu2O3) is that it requires elevated substrate temperatures. To obtain a high transition temperature and a sharp resistive transition, the film is typically deposited on MgO substrates heated to 500oC. Conventional lithographic techniques using resists are not compatible with this requirement. A method is described for preparing MgO substrates to facilitate patterning of the substrate prior to the deposition. This method is particularly suitable for first-level metal deposition and provides planarization for subsequent processing. Further, the process does not involve the use of any chemical that is likely to degrade the intrinsic properties of the film. The technique allows for patterning of single crystal material with high resolution and high density three- dimensional microstructures. In addition, elevated substrate temperatures may be utilized to achieve unique material properties, e.g., epi-type films, good control over film morphology and crystallographic order.

The process is shown schematically in Figs. 1a - 1c. Single crystal magnesium oxide (MgO) 10 with a 100 orientation, is patterned with photoresist using standard semiconductor processing. Vias on the order of 1.5 microns were then chemically etched anisotropically, using a solution of phosphoric acid and water in a ratio of one:one at 65oC, with an etch rate of 50...