Effect of Cu contamination on recombination of O atoms on a plasma-oxidized silicon surface

Journal Article · Mon Jun 01 00:00:00 EDT 2009 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3143107· OSTI ID:21356167

Guha, Joydeep; Khare, Rohit; Stafford, Luc; Donnelly, Vincent M ^[1]; Sirard, Stephen; Hudson, Eric A ^[2]

---

1. Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204 (United States)
2. Lam Research Corporation, Fremont, California 94538 (United States)

In the dual damascene microelectronics integration scheme during the last stage of plasma etching of dielectrics down to underlying Cu layers, Cu is sputtered onto the reactor walls and is believed to cause a drift in etching rates. For photoresist etching in an O{sub 2}-containing plasma, a drop in etching rate suggests that Cu could cause a decrease in the O-atom concentration in the plasma, due perhaps to an increase in the O recombination rate on the chamber walls. We therefore studied the effects of traces of Cu on O recombination on an oxygen plasma-conditioned surface, using the spinning wall technique. With this method, a cylindrical substrate, here coated in situ with sputter-deposited Si and then oxidized in an O{sub 2} plasma, is rotated past skimmers, allowing the surface to be periodically exposed to the plasma and an Auger electron spectrometer with a pressure gauge in a differentially pumped chamber. Between plasma exposures, the sample could also be dosed with Cu from an evaporation source in a differentially pumped chamber. With no Cu on the surface, a pressure rise was observed in the Auger chamber, due to desorption of recombined O{sub 2}. These measurements were used to derive a Langmuir-Hinshelwood recombination coefficient of gamma{sub O}=0.043 for the steady-state oxidized Si, Cu-free surface. The surface was then coated with a small fraction of a monolayer (roughly approx0.002 monolayers of Cu with a dose of approx1.4x10{sup 13} cm{sup -2} and an assumed sticking coefficient of 0.3) and gamma{sub O} was found to increase to 0.069. Further dosing with Cu did not produce any further increases in gamma{sub O}. The initial low gamma{sub O} value could not be recovered by coating the surface with sputter Si, apparently due to rapid outdiffusion of Cu through Si at room temperature. Cu catalyzed recombination of O is ascribed to a redox cycling between Cu{sup +} and Cu{sup 2+} oxidation states.

• OSTI ID: 21356167
• Journal Information: Journal of Applied Physics, Vol. 105, Issue 11; Other Information: DOI: 10.1063/1.3143107; (c) 2009 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUGER ELECTRON SPECTROSCOPY
CONTAMINATION
COPPER
COPPER IONS
DEPOSITION
DESORPTION
DIELECTRIC MATERIALS
ELECTRON SPECTROMETERS
ETCHING
EVAPORATION
MICROELECTRONICS
OXIDATION
OXYGEN
PERIODICITY
PLASMA
PRESSURE GAGES
RECOMBINATION
SILICON
SKIMMERS
SPUTTERING
STEADY-STATE CONDITIONS
SUBSTRATES
TEMPERATURE RANGE 0273-0400 K
CHARGED PARTICLES
CHEMICAL REACTIONS
ELECTRON SPECTROSCOPY
ELEMENTS
EQUIPMENT
IONS
MATERIALS
MEASURING INSTRUMENTS
METALS
NONMETALS
PHASE TRANSFORMATIONS
POLLUTION CONTROL EQUIPMENT
SEMIMETALS
SORPTION
SPECTROMETERS
SPECTROSCOPY
SURFACE FINISHING
TEMPERATURE RANGE
TRANSITION ELEMENTS
VARIATIONS