Methods And Apparatus For Generating Strongly-Ionized Plasmas With Ionizational Instabilities

• US 20110019332A1
• Filed: 08/27/2010
• Published: 01/27/2011
• Est. Priority Date: 02/22/2004
• Status: Active Grant

• Current Assignee: ZOND Incorporated
• Original Assignee: ZOND Incorporated
• Inventors: Chistyakov, Roman
• Granted Patent: US 8,125,155 B2
• Time in Patent Office: Days
• US Class Current: 361/230
• CPC Class Codes: C23C 14/35 by application of a magnetic field, e.g. magnetron sputtering C23C14/3457 takes precedence
• CPC Class Codes: H01J 37/3266 Magnetic control means
• CPC Class Codes: H01J 37/3408 Planar magnetron sputtering
• CPC Class Codes: H01J 37/3455 Movable magnets

Abstract

Methods and apparatus for generating strongly-ionized plasmas are disclosed. A strongly-ionized plasma generator according to one embodiment includes a chamber for confining a feed gas. An anode and a cathode assembly are positioned inside the chamber. A pulsed power supply is electrically connected between the anode and the cathode assembly. The pulsed power supply generates a multi-stage voltage pulse that includes a low-power stage with a first peak voltage having a magnitude and a rise time that is sufficient to generate a weakly-ionized plasma from the feed gas. The multi-stage voltage pulse also includes a transient stage with a second peak voltage having a magnitude and a rise time that is sufficient to shift an electron energy distribution in the weakly-ionized plasma to higher energies that increase an ionization rate which results in a rapid increase in electron density and a formation of a strongly-ionized plasma.

Claims

1-47. -47. (canceled)

48. A strongly-ionized plasma generator comprising:

a) a chamber for confining a feed gas;

b) an anode that is positioned inside the chamber;

c) a cathode assembly that is positioned adjacent to the anode inside the chamber; and

d) a pulsed power supply having an output that is electrically connected between the anode and the cathode assembly, the pulsed power supply generating at the output a voltage pulse having at least one of a controlled amplitude and a controlled rise time that increases an ionization rate so that a rapid increase in electron density and a formation of a strongly-ionized plasma occurs without forming an arc between the anode and the cathode assembly.

49. The plasma generator of claim 48 further comprising a magnet that generates a magnetic field proximate to the cathode assembly.

50. The plasma generator of claim 49 wherein the magnet is movable.

51. The plasma generator of claim 49 wherein the magnetic field generated by the magnet confines the strongly ionized plasmas proximate to the cathode assembly.

52. The plasma generator of claim 48 further comprising a substrate support that is biased with a negative voltage so as to attract positive ions to the sputtered film.

53. The plasma generator of claim 48 further comprising a substrate support comprising a temperature controller that controls a temperature of the substrate.

54. The plasma generator of claim 48 wherein the feed gas comprises at least one of excited and metastable atoms.

55. The plasma generator of claim 48 wherein the pulsed power supply provides enough energy to shift the electron energy distribution of the plasma to higher energies until the strongly ionized plasma is formed.

56. The plasma generator of claim 48 further comprising an energy storage device that is electrically coupled to the cathode assembly, the energy storage device discharging energy into the plasma to enhance the rapid increase in electron density and the formation of the strongly-ionized plasma.

57. The plasma generator of claim 48 wherein the voltage pulse forms ionizational instabilities.

58. The plasma generator of claim 48 wherein the voltage pulse includes at least one low frequency voltage oscillation.

59. The plasma generator of claim 58 wherein an amplitude of the at least one low frequency voltage oscillation is greater than or equal to 50 Volts.

60. The plasma generator of claim 48 wherein a discharge current density of the strongly-ionized plasma is greater than about 0.5 A/cm².

61. The plasma generator of claim 48 wherein the power density of the strongly-ionized plasma is greater than 250 W/cm².

62. The plasma generator of claim 48 wherein the voltage pulse sustains the strongly-ionized plasma.

63. The plasma generator of claim 48 wherein a lifetime of the strongly-ionized plasma is greater than about 200 μ

sec.

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84. An apparatus for generating a strongly-ionized plasma, the apparatus comprising:

a) means for supplying feed gas proximate to an anode and a cathode assembly;

b) means for generating a voltage pulse that forms a plasma between the anode and the cathode; and

c) means for controlling an amplitude and a rise time of the voltage pulse to increase an ionization rate so that a rapid increase in electron density and a formation of a strongly-ionized plasma occurs without forming an arc between the anode and the cathode assembly.

85. The apparatus of claim 84 further comprising shifting an electron energy distribution in the plasma to higher energies that increase an ionization rate.

86. The apparatus of claim 84 further comprising a means for sustaining the strongly-ionized plasma for greater than 200 μ

sec.