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Ti/CrxOy-Cr/Cu/Cr DEVICE INTERCONNECTION METALLURGY

IP.com Disclosure Number: IPCOM000041580D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Dalal, HM: AUTHOR [+3]

Abstract

Future products will require increased current-carrying capability with increased conductivity. Pure copper metallurgy at the second and subsequent levels would be advantageous. Formation of gross amounts of CuAl2 intermetallic at the first-to-second level interfaces in the vias makes it obvious that the aluminum (Al) at first level should also be replaced with copper (Cu). This, however, raised the specter of semiconductor junction "poisoning" by the Cu. To prevent this junction "poisoning", a composite barrier layer consisting of titanium (Ti) plus chromium (Cr) and chromium oxides may be used at the interface. The Ti has the dual function of providing (1) a low barrier Schottky barrier diode interface, when desired, as well as (2) a mechanical barrier to help prevent the penetration of Cu into the semiconductor junction.

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Ti/CrxOy-Cr/Cu/Cr DEVICE INTERCONNECTION METALLURGY

Future products will require increased current-carrying capability with increased conductivity. Pure copper metallurgy at the second and subsequent levels would be advantageous. Formation of gross amounts of CuAl2 intermetallic at the first- to-second level interfaces in the vias makes it obvious that the aluminum (Al) at first level should also be replaced with copper (Cu). This, however, raised the specter of semiconductor junction "poisoning" by the Cu. To prevent this junction "poisoning", a composite barrier layer consisting of titanium (Ti) plus chromium (Cr) and chromium oxides may be used at the interface. The Ti has the dual function of providing (1) a low barrier Schottky barrier diode interface, when desired, as well as (2) a mechanical barrier to help prevent the penetration of Cu into the semiconductor junction. A layer of CrxOy-Cr is then formed on top of the Ti by depositing Cr in a partial H2O environment. This layer is known to have substantially fewer pinholes than using pure Cr. Any small amount of Cu that may penetrate through the pinholes in the Cr layer will be blocked by the Ti below and become immobilized so that it may not reach the junction surface. At second and subsequent levels, only thin layers of pure metallic Cr, deposited both before and after the principal Cu layer, are necessary to provide (1) the required interface surface-bounding layer, and (2) the top surface protection for...