A New Failure Mechanism: Al-Si Bond Pad Whisker Growth During Life Test

Author

Turner, Timothy E. ; Parsons, Robert D.

Author_Institution

United Technologies/MOSTEK, Carrollton, TX, USA

Volume

5

Issue

4

fYear

1982

fDate

12/1/1982 12:00:00 AM

Firstpage

431

Lastpage

435

Abstract

The results are presented of a study conducted to determine reasons for and kinetics of the growth of thin aluminum whiskers from the bond pads of semiconductors. These whiskers were found to grow to lengths of up to 200 µm from thin-film aluminumsilicon on N-type silicon gate metal-oxide semiconductors (NMOS). Whisker growth was found to be due to the compressive stress generated in the metal during wire bonding. The problem is complicated by the presence of silicon grains in the Al-Si film and was found only on parts using gold ball bonds. The growth rate is temperature dependent with a thermal activation energy of 0.7 eV. Copper doping of the metallization as well as the use of aluminum ultrasonically bonded wires were both found to effectively prevent whisker growth.

Keywords

Integrated circuit bonding; Integrated-circuit reliability testing; MOS memory integrated circuits; Aluminum; Bonding; Compressive stress; Failure analysis; Kinetic theory; Life testing; MOS devices; Semiconductor thin films; Silicon; Wire;

fLanguage

English

Journal_Title

Components, Hybrids, and Manufacturing Technology, IEEE Transactions on

Publisher

ieee

ISSN

0148-6411

Type

jour

DOI

10.1109/TCHMT.1982.1135995

Filename

1135995