Closed drift magnetic field ion source apparatus containing self-cleaning anode and a process for substrate modification therewith

Abstract

A process for modifying a surface of a substrate is provided that includes supplying electrons to an electrically isolated anode electrode of a closed drift ion source. The anode electrode has an anode electrode charge bias that is positive while other components of the closed drift ion source are electrically grounded or support an electrical float voltage. The electrons encounter a closed drift magnetic field that induces ion formation. Anode contamination is prevented by switching the electrode charge bias to negative in the presence of a gas, a plasma is generated proximal to the anode electrode to clean deposited contaminants from the anode electrode. The electrode charge bias is then returned to positive in the presence of a repeat electron source to induce repeat ion formation to again modify the surface of the substrate. An apparatus for modification of a surface of a substrate by this process is provided.

1 - 15 . (canceled) 
     
     
         16 . An apparatus for deposition of a film onto a surface of a substrate comprising:
 a first closed drift ion source having an electrically isolated first anode electrode and other components comprising ferromagnetic cathode poles and magnets that form a closed drift magnetic field, said other components being grounded or supporting an electrical float voltage;   a power supply for selectively powering said first anode electrode with a charge bias with a positive charge bias duration and a negative charge bias duration; and   an electron emitter supplying electrons to said first anode electrode when the first electrode charge bias is positive.   
     
     
         17 . The apparatus of  claim 16  wherein the closed drift magnetic field passes through at least one of said other components. 
     
     
         18 . The apparatus of  claim 16  wherein said electron emitter is a second closed drift ion source having a second anode electrode with a second electrode charge bias that is opposite the first electrode charge bias during ion formation and repeat ion formation to support a second closed drift ion source magnetron sputter plasma proximal to said second anode electrode. 
     
     
         19 . The apparatus of  claim 16  wherein said power supply is an alternating current power supply having an output frequency of from 10 to 100 kiloHertz. 
     
     
         20 . The apparatus of  claim 16  wherein said first anode electrode has a plasma confining recess. 
     
     
         21 . The apparatus of  claim 20  wherein said first anode electrode has an inward facing surface that supports a sputter discharge within a closed racetrack magnetic confinement during operation. 
     
     
         22 . An ion source, comprising:
 an electrode; and   a magnet configured to confine electrons within—
 a closed drift confinement region spaced apart from a surface of the electrode when the electrode is biased positive; and 
 a sputtering confinement region at the surface of the electrode when the electrode is biased negative. 
   
     
     
         23 . The ion source of  claim 22  wherein:
 electrons at the closed drift confinement region ignite a first plasma that accelerates away from the electrode when the electrode is biased positive; and 
 electrons at the sputtering confinement region ignite a second plasma that removes contaminants from the surface of the electrode by sputtering when the electrode is biased negative. 
 
     
     
         24 . The ion source of  claim 22  wherein:
 the electrode forms a loop; 
 the magnet includes—
 a first shunt at an outer perimeter of the loop, and 
 a second shunt at an interior of the loop; 
 
 the ion source further comprises a channel between the first and second shunts; 
 the electrode is disposed within the channel; and 
 the closed drift confinement region and the sputtering confinement region are at different respective portions of a magnetic field characterized by magnetic field lines extending across the channel between the first and second shunts. 
 
     
     
         25 . The ion source of  claim 22  wherein:
 the electrode forms a loop within a plane; 
 the ion source is configured to emit plasma in a first direction perpendicular to the plane when the electrode is biased positive; 
 the magnet includes—
 a first shunt at an outer perimeter of the loop, and 
 a second shunt at an interior of the loop; 
 
 the ion source further comprises a channel between the first and second shunts; 
 the closed drift confinement region is at a first magnetic field characterized by magnetic field lines extending across the channel between the first and second shunts; and 
 the sputtering confinement region is at a second magnetic field characterized by magnetic field lines extending between a portion of the first shunt spaced apart from the electrode in the first direction and a portion of the first shunt spaced apart from the electrode in a second direction opposite to the first direction. 
 
     
     
         26 . The ion source of  claim 22 , further comprising sidewalls defining a channel in which the electrode is disposed, wherein the sidewalls are electrically grounded or support an electrical float voltage when the electrode is biased positive and when the electrode is biased negative. 
     
     
         27 . The ion source of  claim 22 , further comprising a standoff that electrically isolates the electrode from the magnet. 
     
     
         28 . The ion source of  claim 27 , further comprising a gas inlet positioned to supply gas to the closed drift confinement region via the standoff when the electrode is biased positive. 
     
     
         29 . The ion source of  claim 22  wherein the electrode includes a recess shaped to confine a sputtering plasma at the surface of the electrode when the electrode is biased negative. 
     
     
         30 . The ion source of  claim 29  wherein the recess is a trench that extends along a length of the electrode. 
     
     
         31 . The ion source of  claim 22 , further comprising:
 a first power supply configured to bias the electrode positive;   a second power supply configured to bias the electrode negative; and   a switch configured to alternate between electrically connecting the first power supply and the electrode and electrically connecting the second power supply and the electrode.   
     
     
         32 . The ion source of  claim 31  wherein the switch is configured to change from electrically connecting the first power supply and the electrode to electrically connecting the second power supply and the electrode in response to a detected voltage across the electrode exceeding a threshold. 
     
     
         33 . The ion source of  claim 22 , further comprising a power supply operably connected to the electrode, wherein the power supply is configured to change a bias on the electrode repeatedly from positive to negative and from negative to positive. 
     
     
         34 . The ion source of  claim 33  wherein the power supply is configured to supply alternating current to the electrode. 
     
     
         35 . The ion source of  claim 34  wherein the power supply is configured to supply the alternating current to the electrode at a frequency within a range from 10 to 100 kilohertz. 
     
     
         36 . An ion source system, comprising:
 a first ion source, including—
 a first electrode, and 
 a first magnet configured to confine electrons within—
 a first closed drift confinement region spaced apart from a surface of the first electrode when the first electrode is biased positive, and 
 a first sputtering confinement region at the surface of the first electrode when the first electrode is biased negative; 
 
   a second ion source operably associated with the first ion source, wherein the second ion source includes—
 a second electrode, and 
 a second magnet configured to confine electrons within—
 a second closed drift confinement region spaced apart from a surface of the second electrode when the second electrode is biased positive, and 
 a second sputtering confinement region at the surface of the second electrode when the second electrode is biased negative; and 
 
   a power supply subsystem configured—
 to bias the first electrode positive while biasing the second electrode negative such that the second electrode supplies electrons to the first electrode via the first closed drift confinement region, and 
 to bias the first electrode negative while biasing the second electrode positive such that the first electrode supplies electrons to the second electrode via the second closed drift confinement region. 
   
     
     
         37 . The ion source system of  claim 36  wherein the power supply subsystem is configured to supply asynchronous alternating currents to the first and second electrodes, respectively. 
     
     
         38 . The ion source system of  claim 36  wherein the first and second electrodes are interchangeable. 
     
     
         39 . The ion source system of  claim 36  wherein:
 the first and second ion sources are oriented to emit plasma in an emission direction; and 
 the ion source system further comprises an elongate gas distribution manifold disposed between the first and second ion sources in a plane perpendicular to the emission direction. 
 
     
     
         40 . The ion source system of  claim 39  wherein a length of first ion source, a length of the second ion source, and a length of the gas distribution manifold are parallel to one another.