Browse Prior Art Database

Al(Cu, Pd) Alloys Interconnects

IP.com Disclosure Number: IPCOM000103245D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Related People

Ho, PS: AUTHOR [+2]

Abstract

This disclosure describes an interconnect metallurgy which can improve the reliability against stress-induced migration and electromigration by adding Pd in Al(Cu).

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Al(Cu, Pd) Alloys Interconnects

      This disclosure describes an interconnect metallurgy which can
improve the reliability against stress-induced migration and
electromigration by adding Pd in Al(Cu).

      It is known that the Al grain boundary diffusion is the main
diffusion mechanism in thin Al film.  The reliability degradation of
Al interconnects is primarily caused by the motion of Al along grain
boundary due to the external driving forces.  A reliable Al
metallization can be developed, if the Al grain boundary diffusion
can be greatly reduced.  It has been shown that movement of Al along
grain boundary can be slowed down by the impurities of Cu and Pd. The
Cu impurity in Al is usually uniformly distributed in the
as-deposited film.  When the Al(Cu) interconnects are annealed at
high temperature, the large CuAl2 precipitates will be grown and also
act as sinks for Cu, and the small precipitates will be diminished to
reduce the surface-free energy.  The growth of large precipitates
reduces the Cu atoms and the number of precipitates along the Al
grain boundaries which decrease the effect in blocking Al grain
boundary motion.  Under this circumstance voids and hillocks can be
easily formed at these precipitate-free grain boundaries and cause
the electromigration and stress-induced failure.  The microstructure
of Al(Cu) can be modified by the addition of Pd.  The solubility of
Pd in Al is nil according to the Al-Pd phase diagram.  The growth
process o...