Investigations of fluxless flip-chip bonding using vacuum ultraviolet and formic acid vapor surface treatment

We studied the effects of surface treatment using vacuum ultraviolet (VUV) and formic acid vapor for SnCu-Au flip-chip bonding. Sn-rich solder bumps are widely used for flip-chip interconnections because of low melting temperature and high mechanical strength. For fine pitch interconnections, surfac...

Full description

Saved in:
Bibliographic Details
Main Authors: Unami, N., Noma, H., Sakuma, K., Shigetou, A., Shoji, S., Mizuno, J.
Format: Conference Proceeding
Language:eng ; jpn
Subjects:
Bonding
Flip chip
Silicon
Surface contamination
Surface treatment
Three dimensional displays
Tin
Online Access:Request full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We studied the effects of surface treatment using vacuum ultraviolet (VUV) and formic acid vapor for SnCu-Au flip-chip bonding. Sn-rich solder bumps are widely used for flip-chip interconnections because of low melting temperature and high mechanical strength. For fine pitch interconnections, surface modification is needed before the bonding process. X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) were used to investigate Sn surfaces. The results showed how the VUV/O 3 surface treatment removes the carbon-based organic contaminants from the Sn surfaces and the formic acid treatment reduces the metal oxides of Sn. Combination of VUV/O 3 and formic acid treatments improved shear strength of a bonded sample. The average shear strength of each bump with VUV/O 3 and/or formic acid treatment is about twice that of a bump with no treatment.
ISSN:1550-5723
DOI:10.1109/ISAPM.2011.6105704