Designing planar magnetron cathodes: Analysis and experiment

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:321045

Garcia, M ^[1]

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1. Lawrence Livermore National Lab., CA (United States)

Planar magnetron cathodes have arching magnetic field lines which concentrate plasma density to enhance ion bombardment and sputtering. Typical parameters are: helium at 1 to 300 milli-torr, 200 to 2000 gauss at the cathode, 200 to 800 volts, and plasma density decreasing by ten to a thousand times within 2 to 10 cm from the cathode. A 2D, quasineutral, fluid model yields formulas for the plasma density: n(x,y), current densities: j(x,y), j{sub e}(x,y), j{sub +}(x,y), the electric field: E{sub y}(y), and the voltage between the cathode surface and a distant plasma. Experiments shows that T{sub e}(3{r_arrow}8 eV) adjusts to ensure that {alpha}{sub 0}{tau} {approx} 2.5 in helium for ionization rate {alpha}{sub 0}(10{sup 4}{r_arrow}10{sup 5} s{sup {minus}1}), and electron transit time to the unmagnetized plasma {tau} (10{r_arrow}100 {micro}s). Helium glow discharge cathode fall {alpha}{sub 0}{tau} is about 2.5, though this occurs at much higher voltage.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 321045
• Report Number(s): CONF-970559--
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
CATHODES
DESIGN
ELECTRIC POTENTIAL
ELECTRON TEMPERATURE
MAGNETIC CONFINEMENT
MAGNETRONS
PLASMA DENSITY