Flip chip metallization

• US 6,597,069 B1
• Filed: 09/14/2000
• Issued: 07/22/2003
• Est. Priority Date: 10/14/1998
• Status: Expired due to Term

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Gregus, Jeffrey Alan, Degani, Yinon
• Primary Examiner(s): Flynn, Nathan J.
• Assistant Examiner(s): Erdem, Fazli
• Application Number:
  US09/661,741
• Time in Patent Office: 1,041 Days
• Field of Search: 257/643, 257/673, 257/741, 257/753, 257/778, 257/780, 257/781, 438/612, 438/613, 438/614, 438/617
• US Class Current: 257/778
• CPC Class Codes: H01L 2224/05001 Internal layers
• CPC Class Codes: H01L 2224/05022 the internal layer being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/05027 the internal layer extending out of an opening
• CPC Class Codes: H01L 2224/0508 being stacked
• CPC Class Codes: H01L 2224/05124 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/05572 the external layer extending out of an opening
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/05671 Chromium [Cr] as principal constituent
• CPC Class Codes: H01L 2224/13099 Material
• CPC Class Codes: H01L 2224/131 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 24/03 Manufacturing methods
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/11 Manufacturing methods for bumps on insulating substrates H01L21/4853
• CPC Class Codes: H01L 24/13 of an individual bump connector
• CPC Class Codes: H01L 2924/0001 Technical content checked by a classifier
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01004 Beryllium [Be]
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01018 : Argon [Ar]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01024 : Chromium [Cr]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01051 : Antimony [Sb]
• CPC Class Codes: H01L 2924/01072 : Hafnium [Hf]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/19041 : being a capacitor

Abstract

The specification describes techniques for applying under bump metallization (UBM) for solder bump interconnections on IC chips with Al bonding sites. The UBM of the invention comprises a copper layer applied directly to the aluminum bonding sites. Reliable bonds are obtained if the Al surface is a nascent surface. Such a surface can be provided by back sputtering an aluminum bonding site, or by a freshly sputtered aluminum layer. The copper layer is deposited on the nascent aluminum surface in e.g. a cluster tool without breaking vacuum. The UBM can be patterned using subtractive techniques.

Claims

1. An integrated circuit package comprising:

a. an integrated circuit (IC) chip attached to a support substrate,

b. an aluminum layer on the IC chip, the aluminum layer having a surface free of native oxide,

c. a copper layer directly on the surface of the aluminum layer,

d. a solder bump directly on the copper layer.