1. Use of a commercial RF Plasma Cleaner in eliminating
background
Use of a commercial RF Plasma Cleaner in eliminating
advenitious carbon contamination in an XPS system
Our group designs mirrors that are reflective in the VUV, with the goal of designing a lunar-based magnetosphere observing mirror. Contamination on the surface of the mirror has serious effects on its reflectivity. We study practical ways to store and ship the mirror as well as ways to eliminate the inevitable contamination.
Liz Strein, David Allred, department of physics and astronomy
When studying the removal of a thin layer of adventitious carbon it is critical to ensure that the instruments used to characterize the surface are not contributing to the contamination
We found that the antechamber of the XPS system deposited carbon onto clean and dirty samples, making it impossible to use XPS as a way to characterize surface cleanliness. Using the RF Plasma Cleaner to clean the chamber virtually eliminates contamination from the chamber. By ensuring that the chamber was not a source of contamination, XPS could be used as a characterization technique. As a result, we were able to study the effectiveness of various cleaning treatments
image from
used with permission
Contamination’s Effect
After
Before
J. Tveekrem, Contamination effects on EUV optics, NASA Technical Report TP (1999
Used with permission
XPS Antechamber:
a source of contamination
without the aid of a RF Plasma Cleaner
Methodology
Acknowledgments
*Ron Vane and Gabe Morgan for their excellent product, the EVACTRON® C RF Decontamination System
*Dr. R. Steven Turley , Dr. Matt Linford, and Lei Pei
*College of Physical and Mathematical Sciences for funding
Previous to their exposure to the XPS system, these samples were cleaned using atomic oxygen in air, by placing the samples within 1 cm of an excimer lamp in air for at least 5 min. The oxidation process frees the SiO2 of adventitious carbon (AC). Use of spectroscopic ellipsometry (SE) provides a method of characterizing surface cleanliness. With the use of the lamp, the apparent thickness of the oxide layer (really a layer of oxide and AC) would decrease to 1.8 nm, the thickness of the native oxide. When we introduced the clean samples to the XPS antechamber, we saw an increase in the apparent oxide thickness and XPS scans showed a large carbon presence. However, after we installed Evactron-C plasma decontamination system, adventitious carbon was virtually eliminated