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Reactive Metal Contact Diffusion Barrier

IP.com Disclosure Number: IPCOM000042387D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kleinsasser, AW: AUTHOR

Abstract

Stable carbide or nitride (or mixed) diffusion barrier films grown on reactive contact metals provide chemical stability and low resistivity. Nonreactive contact metals may be used to complete the contact structure, as shown in the figure. One difficulty in forming electrical contacts involving a highly reactive metal (such as Nb or Ti) and a relatively unreactive metal (such as Pb or Au) is that reactive species tend to diffuse through the unreactive material and combine with the reactive material at the interface. The resulting layer acts as a tunnel barrier and contributes to the contact resistance between the two materials.

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Reactive Metal Contact Diffusion Barrier

Stable carbide or nitride (or mixed) diffusion barrier films grown on reactive contact metals provide chemical stability and low resistivity. Nonreactive contact metals may be used to complete the contact structure, as shown in the figure. One difficulty in forming electrical contacts involving a highly reactive metal (such as Nb or Ti) and a relatively unreactive metal (such as Pb or Au) is that reactive species tend to diffuse through the unreactive material and combine with the reactive material at the interface. The resulting layer acts as a tunnel barrier and contributes to the contact resistance between the two materials. In cases in which a stable contact is of importance (for example, in superconducting digital circuits, in which the total value of a resistor, with contacts included, must be very carefully controlled) the gradual increase in resistance with time represented by this effect must be avoided. The reactive material (such as Nb or Ti) is passivated by the barrier film so that the subsequent deposition of another metal results in a low resistivity stable interface. A reactive plasma (containing nitrogen, methane, or cyanogen, for example) is used to grow a thin layer (on the order of 100 A) of nitride, carbide, or mixed carbide/ nitride on the surface of the (Nb or Ti) metal. This layer is both conductive and relatively stable chemically, having reactivity very much reduced from the bare metal. This great...