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Plasma Cleaning of RABiTS Metal Substrate to Improve Adhesion of Oxide Layers

IP.com Disclosure Number: IPCOM000035583D
Publication Date: 2005-Jan-25
Document File: 1 page(s) / 63K

Publishing Venue

The IP.com Prior Art Database

Abstract

In the coated conductor RABiTS architecture the HTS layer grows in the same biaxial orientation as the substrate. To do this, the texture has to be is copied from the substrate through the buffer layers into the HTS layer. The buffer seed layer needs a clean metal template with a sulfur c(2x2) superstructure to nucleate from. Otherwise, the preferred orientation of the seed layer is (111). In addition a common failure of the buffer stack is delamination at the metal substrate / oxide seed layer interface. Delamination is caused by mismatch in thermal expansion, stresses in the film an inherently weak interface between the metal and the seed oxide interface. The strength of the interface changes when oxide forms at the interface.

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Plasma Cleaning of RABiTS Metal Substrate to Improve Adhesion of Oxide Layers

General Purpose of Invention

In the coated conductor RABiTS architecture the HTS layer grows in the same biaxial orientation as the substrate. To do this, the texture has to be is copied from the substrate through the buffer layers into the HTS layer. The buffer seed layer needs a clean metal template with a sulfur c(2x2) superstructure to nucleate from. Otherwise, the preferred orientation of the seed layer is (111). In addition a common failure of the buffer stack is delamination at the metal substrate / oxide seed layer interface. Delamination is caused by mismatch in thermal expansion, stresses in the film an inherently weak interface between the metal and the seed oxide interface. The strength of the interface changes when oxide forms at the interface.

Prior Art

To establish a clean surface the substrate is annealed in a reducing environment at high temperature to clean the surface. H2S in the atmosphere creates the sulfur superstructure as soon as all adsorbants are removed. Careful control of the oxide use during all subsequent deposition steps controls the strength of the interface.

Disadvantages of Prior Art

The thermal anneal is a very slow process. A given sample has to be annealed anywhere between 5-15 minutes to establish a clean surface that can build a S-superstructure. Also the oxygen control is very critical during this state, since the anneal is done at very low total...