By Topic

Semiconductor interlevel shorts caused by hillock formation in Al-Cu metallization

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$33 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

3 Author(s)
Puttlitz, A.F. ; IBM Corp., Essex Junction, VT, USA ; Ryan, J.G. ; Sullivan, T.D.

A new failure mode in AlCu and AlCuSi metallization is described in which interlevel metal short circuiting occurs between two or more levels of metal. Shorts are caused by theta-phase (Al2Cu) hillocks which nucleate and grow during high-temperature vacuum heat treatment and processing, Hillock growth occurs at high-energy sites, such as silicon precipitates and grain boundary nodal points. The growth of Al2Cu hillocks depends on the heat-treatment/processing temperature and aluminum film purity. The growth kinetics indicates that grain boundary diffusion is the dominant mass transport mechanism. Methods used to limit theta-phase hillock formation and growth concentrate on the diffusion and nucleation mechanisms involved. Decreasing the heat-treatment/processing temperature slows the atomic diffusion required for hillock growth, and it delays, but does not prevent, theta-phase hillock formation. A 1-h heat treatment (213 Pa, N 2 ambient) at 350°C produces a high density of large hillocks. Hillock density and height are generally reduced at 300°C. Altering the layered structure of a metallization alters Al2Cu hillock growth. Deposition of a hard coating as a cap on the layered structure of an aluminum-based metallization mechanically suppresses hillock formation. A layer of pure aluminum deposited beneath the aluminum-copper layer acts as a sink for copper and delays hillock formation. Increasing film copper content reduces hillock formation: theta-phase hillocks, up to 1.3 μm in height, are observed in films with 1 wt.% copper, whereas negligible (<0.2 μm in height) hillock formation is observed in 11 wt.% Cu films

Published in:

Components, Hybrids, and Manufacturing Technology, IEEE Transactions on  (Volume:12 ,  Issue: 4 )