Measurement of dynamic strain during ultrasonic Au bump formation on Si chip

Citation
M. Hizukuri et T. Asano, Measurement of dynamic strain during ultrasonic Au bump formation on Si chip, JPN J A P 1, 39(4B), 2000, pp. 2478-2482
Citations number
4
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Volume
39
Issue
4B
Year of publication
2000
Pages
2478 - 2482
Database
ISI
SICI code
0021-4922(200004)39:4B<2478:MODSDU>2.0.ZU;2-Y
Abstract
The strain generated at the surface of a Si chip during the ultrasonic form ation of a Au bump was dynamically measured using strain gauges fabricated on the chip. The piezoresistive-type strain gauge was designed to be sensit ive to unidirectional strain at the surface. Measured results show that the magnitude and direction of strain strongly depend on the relative position to the Au bump and bonding sequence. It has been found that the maximum st rain is generated near the periphery of the bump during the application of ultrasonic vibration, while the maximum residual strain appears near the ce nter of the bump. Analysis with the finite element method (FEM) has shown a good qualitative agreement with the measured results. Effects of direct bu mp formation on MOS devices were examined by time dependent dielectric brea kdown (TDDB) tests and measurement of Bat band voltage of metal oxide semic onductor (MOS) capacitors. The reliability of MOS gate oxide was found to d ecrease due to both ultrasonic and residual strain.