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Mask for Etching SiC

IP.com Disclosure Number: IPCOM000095927D
Original Publication Date: 1964-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Liebmann, W: AUTHOR

Abstract

In the fabrication of semiconductor components, etching techniques are frequently employed. In addition to etching the entire semiconductor surface for polishing or cleaning purposes, it is often also necessary to restrict the etching process to discrete areas of the semiconductor element. For that purpose, the semiconductor element is coated with a mask resistant to the etchant to be used and provided with appropriate apertures in the region of the areas to be etched. Where semiconductor components are made of SiC, difficulties arise as this extremely hard and chemically resistant material is attacked only by very powerful oxidants, such as a sodium peroxide melt. Also, such oxidants attack all of the known mask materials.

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Mask for Etching SiC

In the fabrication of semiconductor components, etching techniques are frequently employed. In addition to etching the entire semiconductor surface for polishing or cleaning purposes, it is often also necessary to restrict the etching process to discrete areas of the semiconductor element. For that purpose, the semiconductor element is coated with a mask resistant to the etchant to be used and provided with appropriate apertures in the region of the areas to be etched. Where semiconductor components are made of SiC, difficulties arise as this extremely hard and chemically resistant material is attacked only by very powerful oxidants, such as a sodium peroxide melt. Also, such oxidants attack all of the known mask materials.

This problem is avoided in a two-stage process. The SiC crystal surface to be etched has first evaporated on it a thin but dense platinum layer. Platinum is not attacked by peroxide melts at the commonly used etching temperatures of 400 to 500 degrees C. The platinum layer is then coated in the customary manner with an acid-resistant photosensitive varnish layer, i. e., photoresist. In this, apertures are produced by exposure to light at those points where the etching of the silicon carbide is to take place. The crystal is then treated with aqua regia so that the platinum is dissolved away below the apertures in the varnish layer. Then, the crystal is placed into a sodium peroxide melt and the silicon carbide is attacked o...