Chemical removal of oxide layer from chip pads

• US 20090081875A1
• Filed: 09/22/2008
• Published: 03/26/2009
• Est. Priority Date: 09/21/2007
• Status: Active Grant

• Current Assignee: Translarity, Inc.
• Original Assignee: Advanced Inquiry Systems, Inc.
• Inventors: Ruffler, Jens
• Granted Patent: US 8,536,062 B2
• Time in Patent Office: Days
• US Class Current: 438/706
• CPC Class Codes: H01L 21/02068 during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers
• CPC Class Codes: H01L 2224/02166 Collar structures
• CPC Class Codes: H01L 2224/05001 Internal layers
• CPC Class Codes: H01L 2224/05082 Two-layer arrangements
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 24/03 Manufacturing methods
• CPC Class Codes: H01L 24/05 of an individual bonding area
• 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 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 Silicon [Si]
• CPC Class Codes: H01L 2924/01018 Argon [Ar]
• CPC Class Codes: H01L 2924/01033 Arsenic [As]
• CPC Class Codes: H01L 2924/01072 Hafnium [Hf]
• CPC Class Codes: H01L 2924/01075 Rhenium [Re]
• CPC Class Codes: H01L 2924/14 Integrated circuits

Abstract

Methods are provided for removing an oxide layer from a metal pad on an integrated circuit in order to reduce contact resistance. In one embodiment, aluminum oxide, on the surface of a bond pad substantially comprised of aluminum, is reacted with a first chemical agent to form an inorganic salt, and the inorganic salt is then reacted with a second chemical agent leaving a substantially bare, that is, unoxidized, aluminum surface.

Claims

1. A method of removing oxide from integrated circuit bond pads, comprising:

providing a wafer having a topside passivation layer formed over a pad layer, the topside passivation layer having pad openings formed therein;

forming a patterned photoresist layer over the topside passivation layer such that at least portions of the pads are exposed;

disposing the wafer in a processing chamber and introduce a fluorine-containing gas;

introducing a solvent into the processing chamber; and

exhausting the processing chamber.

2. The method of claim 1, wherein a layer of aluminum oxide is disposed over at least a portion of the exposed portions, and the fluorine-containing gas is hydrogen fluoride.

3. The method of claim 2, wherein the solvent comprises a materials selected from the group consisting of water vapor, xylene, and nitric acid.

4. The method of claim 3, further comprising:

introducing, subsequent to introducing the solvent, an inert gas into the processing chamber.

5. The method of claim 4, further comprising:

storing the wafer, subsequent to introducing the inert gas, in an oxygen-free environment.

6. A method of removing oxide from integrated circuit bond pads, comprising:

providing a wafer having at least one pad thereon, and having a topside passivation layer thereon, the topside passivation layer patterned such that at least a first portion of the at least one pad is covered by the topside passivation layer and at least a second portion of the at least one pad is not covered by the topside passivation layer;

exposing the wafer to gaseous HF;

exposing the wafer to a solvent;

exposing the wafer to an inert gas; and

maintaining the wafer in an inert gas environment.

7. The method of claim 6, wherein the solvent is water vapor.