Fluxless bonding using vacuum ultraviolet and formic acid for 3D interconnects

Katsuyuki Sakuma, Naoko Unami, Shuichi Shoji, Jun Mizuno

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

We have developed a novel surface treatment process using vacuum ultraviolet (VUV) light with a wavelength of 172 nm and formic acid vapor. A previous study showed that the VUV process can help remove the organic contaminants on the bonding surfaces and improve the shear strength [1]. This new work focuses on studying the effects of VUV/O3 and formic acid treatments. The formic acid (HCOOH) vapor removes the metal oxides from the surfaces before the bonding process. Evaporated Cu/Sn and immersion Au were used for the bonding micro-bumps and bonding pads in our evaluations. Different cleaning conditions with VUV/O3, formic acid vapor, or both were compared and evaluated. X-ray Photoelectron Spectroscopy (XPS) was used to study the surface elemental composition of the micro-bumps and pad surfaces before and after the cleaning process. The photoelectron spectra of Cls, Sn3d, and Au4f were obtained with XPS. The XPS results showed the atomic carbon concentrations were significantly decreased by the VUV/O3 treatment process, while the Sn and Au concentrations were increased by the VUV/O3 and formic acid treatment because of the removal of the organic contaminants and metal oxides from the surfaces. The bonding strength of the Cu/Sn bumps was evaluated using a shear test tool. The results shows that the combination of VUV/O 3 and formic acid treatment obtains the highest average shear strength among the treatments tested, with a shear strength almost 2.5 times stronger than the untreated samples.

Original languageEnglish
Title of host publicationMaterials Research Society Symposium Proceedings
Pages299-307
Number of pages9
Volume1249
Publication statusPublished - 2010
Event2010 MRS Spring Meeting - San Francisco, CA
Duration: 2010 Apr 52010 Apr 9

Other

Other2010 MRS Spring Meeting
CitySan Francisco, CA
Period10/4/510/4/9

Fingerprint

formic acid
Formic acid
Vacuum
vacuum
acids
shear strength
Shear strength
X ray photoelectron spectroscopy
Vapors
photoelectron spectroscopy
vapors
Oxides
cleaning
contaminants
metal oxides
Cleaning
Metals
Impurities
x rays
Photoelectrons

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering
  • Mechanics of Materials

Cite this

Sakuma, K., Unami, N., Shoji, S., & Mizuno, J. (2010). Fluxless bonding using vacuum ultraviolet and formic acid for 3D interconnects. In Materials Research Society Symposium Proceedings (Vol. 1249, pp. 299-307)

Fluxless bonding using vacuum ultraviolet and formic acid for 3D interconnects. / Sakuma, Katsuyuki; Unami, Naoko; Shoji, Shuichi; Mizuno, Jun.

Materials Research Society Symposium Proceedings. Vol. 1249 2010. p. 299-307.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Sakuma, K, Unami, N, Shoji, S & Mizuno, J 2010, Fluxless bonding using vacuum ultraviolet and formic acid for 3D interconnects. in Materials Research Society Symposium Proceedings. vol. 1249, pp. 299-307, 2010 MRS Spring Meeting, San Francisco, CA, 10/4/5.
Sakuma K, Unami N, Shoji S, Mizuno J. Fluxless bonding using vacuum ultraviolet and formic acid for 3D interconnects. In Materials Research Society Symposium Proceedings. Vol. 1249. 2010. p. 299-307
Sakuma, Katsuyuki ; Unami, Naoko ; Shoji, Shuichi ; Mizuno, Jun. / Fluxless bonding using vacuum ultraviolet and formic acid for 3D interconnects. Materials Research Society Symposium Proceedings. Vol. 1249 2010. pp. 299-307
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