Browse Prior Art Database

Process for Making Low Resistivity Contacts to Semiconductors

IP.com Disclosure Number: IPCOM000109628D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 1 page(s) / 61K

Publishing Venue

IBM

Related People

Aboelfotoh, MO: AUTHOR [+4]

Abstract

Disclosed is a novel process for making low resistivity Copper Germanium (Cu3Ge) ohmic contacts to elemental and compound semiconductors. The technique provides for low resistivity ohmic contacts coupled with low temperature processing to ensure device protection during fabrication of contacts and interconnects. Prior art teaches a way of fabricating ohmic contacts, e.g., Cobalt Silicide, Tungsten Silicide, etc., but requires elevated temperatures, typically on the order of 400~C or more, thus restricting the use of organic lift-off stencils. In addition, these high temperatures can introduce dopant redistribution within the device and change operational characteristics as well as reducing device yield.

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Process for Making Low Resistivity Contacts to Semiconductors

       Disclosed is a novel process for making low resistivity
Copper Germanium (Cu3Ge) ohmic contacts to elemental and compound
semiconductors.  The technique provides for low resistivity ohmic
contacts coupled with low temperature processing to ensure device
protection during fabrication of contacts and interconnects.  Prior
art teaches a way of fabricating ohmic contacts, e.g., Cobalt
Silicide, Tungsten Silicide, etc., but requires elevated
temperatures, typically on the order of 400~C or more, thus
restricting the use of organic lift-off stencils.  In addition, these
high temperatures can introduce dopant redistribution within the
device and change operational characteristics as well as reducing
device yield.  The disclosed process avoids the above elevated
temperatures, allows for organic masking, and reduces or avoids
diffusion of metals and dopants within the device.  Selected area
deposition of low resistivity Copper-Germanium (Cu3Ge) can be
achieved utilizing the following process:

      A photoresist stencil is generated using standard semiconductor
processing on the host substrate.

      Vacuum deposition at room temperature of a film of germanium on
the order of 78 nm, followed by a film of copper with a thickness on
the order of 122 nm is deposited.

      The host substrate is then heated to 100~C for one hour,
allowing a solid-state reaction to form the alloy Cu3Ge.

    ...