AVS 57th International Symposium & Exhibition
    Plasma Science and Technology Thursday Sessions
       Session PS-ThM

Paper PS-ThM5
Mass-selected Ion Beam Study on Reactive Ion Etching Mechanisms for Pt, Co and PtCo Thin Films

Thursday, October 21, 2010, 9:20 am, Room Aztec

Session: Plasma Surface Interactions (Fundamentals & Applications) III
Presenter: K. Karahashi, Osaka University, Japan
Authors: K. Karahashi, Osaka University, Japan
T. Ito, Osaka University, Japan
S. Hamaguchi, Osaka University, Japan
Correspondent: Click to Email
Recently limited choices of microfabrication techniques for magnetic thin film processing have been recognized as one of the major impediments for the development of microelectronics devices such as magnetic random access memory (MRAM) and read/write heads for magnetic data storage. For magnetic films, Ar ion milling is essentially the only etching technique that is currently available in actual manufacturing processes. Whereas Ar ion milling is a well established technology, it does not provide etching selectivity that the industry currently desires. For magnetic thin films, reactive ion etching processes based on Cl2 or CO chemistry have been considered so far as good candidates. In this study, therefore, we have examined etching processes of PtCo alloy thin films by energetic Cl+ ions. More specifically we have measured desorbed products and etching yields of Pt, Co, and PtCo, using a mass-selected ion beam system. With the use of the ion beam system, we inject mono-energetic single-species ions (i.e., Cl+ or Ar+ ions) to the sample surface in ultra-high vacuum conditions. The reaction chamber, where the sample is placed, is equipped with a quadrupole mass spectrometer (QMS), a temperature programmed desorption (TPD) system, and an X-ray photoelectron spectroscopy (XPS). It has been found that the etching yields of Pt films by Cl+ ion injections are larger than those of Co films by Ar+ ion injections, and the etching yields of PtCo depend on its composition ratio. It has been also found that platinum chloride (PtClx) desorption are detected with QMS under Cl+ ion injections. These results indicate that the yield of Pt is increased by the formation of PtClx on the surface. We have also studies temperature dependence of the etching yield. With a higher temperature, the yield of Pt by Cl+ ion injections is lower because chlorine coverage on the surface is also lower at a higher surface temperature. Therefore temperature control in Pt or PtCo etching processes is of significant importance for better process control. Etching characteristics of PtCo by CO+ ion beams will be also discussed.