Sputtering yield of chromium by argon and xenon ions with energies from 50 to 500 eV

Abstract

Abstract.A radioactive tracer technique is described for the quantitative measurement of the sputtering yield of a target material electroplated on a copper substrate. Sputtering yields of chromium by argon and xenon ions with energies from 50 to 500eV are reported. The ion beams, having a current density ranging from 0.01 to 0.1mA/cm 2 at an operating pressure of 2 x 10 -5 Torr, were produced by a low-energy ion gun. The sputtered atoms were collected on an aluminum foil surrounding the target. 51Cr was used as the tracer isotope. The results indicate that the radioactive tracer technique is sensitive enough in measuring the extremely small amount of sputtered material at low ion currents and low ion energies. 79.20.Nc, 29.25.Ea Ion engines are being considered for many future space missions to meet both the primary and the auxiliary propulsion requirements [1,2]. Life limiting tests, lasting nearly 10,000 h, have been conducted on 30 cm and 5 cm diameter electron bombardment mercury ion thrusters [3,4]. From these tests, it has been observed that the most serious life limiting phenomena is the sputter erosion of the discharge chamber components which come in contact with the ions. Recent extended testing of a 30 cm diameter thruster using xenon ions also revealed significant component erosion [5]. The sputter erosion with subsequent deposition of material on to the adjacent structures remains as the major technology issue of these thrusters [6]. PACS:In the discharge chamber where the ions are created, the ions are expected to have energies less than 100 eV. However, the sputtering yield data at low energy, particularly below the 100 eV region, show considerable variations [7][8][9]. In view of this, an experimental study was conducted to obtain sputtering yield data at low ion energies. In previous sputtering studies, the targets were immersed like a negative Langmuir probe in a low-pressure, high-density mercury or noble gas plasma maintained between a separate independent cathode and an anode. A general disadvantage of the plasma discharge systems is that the irradiation conditions are somewhat poorly defined and impurities in the plasma could contribute to the measured yields. Moreover, at low ion energies, different charge states of the ions could provide erroneous values of the sputtering yield. In the present investigation, a low-energy ion gun was used to generat e ions with a well-defined energy. Results are reported here on the sputtering yields of chromium by argon and xenon ions having energies from 50 to 500 eV.

Combined Manufacturing Process of Copper Electrodes for Micro Texturing Applications (AMSME)

“…Sputtering is the erosion of solid surfaces during the bombardment with energy ions [ 42 , 43 ]. One of its applications, cathodic spraying, is the deposition of thin films on the material surface with ion beam and plasma (PSD and IBSD respectively) [ 44 , 45 ].…”