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Structure and method for everted interconnect

IP.com Disclosure Number: IPCOM000238191D
Publication Date: 2014-Aug-07
Document File: 4 page(s) / 51K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed are a structure and method for an everted interconnect. The interconnect via is formed using a sacrificial mandrel to provide a novel structure with a liner formed on the outside of a lithographically-patterned mandrel pillar (i.e. everted interconnect liner) and no liner interface between via and underlying wire.

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Structure and method for everted interconnect

High via contact resistivity limits performance for sub-22nm technologies. Dual-damascene fill requires a bottom-thick Physical Vapor Deposited (PVD) liner (typically Tantalum (Ta) or Tantalum Nitride (TaN)), which is a major contributing factor to via contact resistance (Rc). Interfacial resistances between Copper (Cu)-Ta-TaN dominates at these liner thicknesses (bulk resistivity is no longer a sole contributor).

Known solutions include an etchback (resputter) of the barrier liner from the via bottom. The use of conformal depositions (e.g., Atomic Layer Deposition (ALD)) avoids bottom-thick liner. Another solution is to increase the cross-sectional area of the via bottom.

These solutions are not effective, however, due to the presence of microtrenching, yield degradation, and Inter-Layer Dialectric (ILD) damage. In addition, the solutions are not robust enough (i.e. not dense enough) to be effective as a barrier. These approaches also cause interlevel Time-Dependent Dialectric Breakdown (TDDB) concerns.

The novel solution is a structure and method to provide via interconnect without introducing interfacial resistance to the underlayer wiring level, and without displacing the primary conductive material in the via. The interconnect via is formed using a sacrificial mandrel to provide a novel structure with a liner formed on the outside of a lithographically-patterned mandrel pillar (i.e. everted interconnect liner) and no liner interface between via and underlying wire.

Multiple embodiments are provided to enable:

1. Liner outside of mandrel via pillar (everted interconnect liner)

2. Metal-to-me...