Impact of gaseous additives on copper CMP in neutral and alkaline solutions using a CAP system

Darren Denardis, Toshiro Doi, J Brent Hiskey, Koichiro Ichikawa, Daizo Ichikawa, Ara Philipossian

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

A controlled atmosphere polishing (CAP) system was used to determine the effects of various chamber gases on copper chemical mechanical polishing (CMP) in the presence and absence of NH4OH and H2O2. Using 500 kPa oxygen or nitrogen has only slight effects on copper removal rates in the presence of 1 wt % H2O2. Polishing without H 2O2, performed with controlled oxygen partial pressure, demonstrates removal rates that are 4 times higher than using nitrogen. Polishing using inert gases alone demonstrates an oxidant-starved system that reflects little dependence on wafer pressure or velocity. Addition of NH 4OH (pH 10) to experiments using oxidizing gases, such as oxygen and air, increases removal rates up to 3×. Removal rates vary linearly with oxygen partial pressure using oxidizing gases for experiments using NH 4OH at pH 10. A trend indicating a transition from chemical to mechanical control is observed when NH4OH concentration is increased at constant oxygen pressure. A copper removal mechanism in the presence of dissolved oxygen has been developed that highlights a buildup of oxidized copper at the wafer surface. The ability to perform CMP in a pressurized gaseous environment has shown that copper removal is a process of mechanical removal, dissolution of abraded material, and copper-oxygen reactions at the wafer surface.

Original languageEnglish (US)
JournalJournal of the Electrochemical Society
Volume152
Issue number11
DOIs
StatePublished - 2005

Fingerprint

controlled atmospheres
Chemical mechanical polishing
Polishing
polishing
Copper
Protective atmospheres
copper
Oxygen
oxygen
Gases
wafers
Partial pressure
partial pressure
Nitrogen
gases
Noble Gases
nitrogen
Dissolved oxygen
Inert gases
Oxidants

ASJC Scopus subject areas

  • Electrochemistry
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

Cite this

Impact of gaseous additives on copper CMP in neutral and alkaline solutions using a CAP system. / Denardis, Darren; Doi, Toshiro; Hiskey, J Brent; Ichikawa, Koichiro; Ichikawa, Daizo; Philipossian, Ara.

In: Journal of the Electrochemical Society, Vol. 152, No. 11, 2005.

Research output: Contribution to journalArticle

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