High deposition rate sputtering

Abstract

Methods and apparatus for high-deposition sputtering are described. A sputtering source includes an anode and a cathode assembly that is positioned adjacent to the anode. The cathode assembly includes a sputtering target. An ionization source generates a weakly-ionized plasma proximate to the anode and the cathode assembly. A power supply produces an electric field between the anode and the cathode assembly that creates a strongly-ionized plasma from the weakly-ionized plasma. The strongly-ionized plasma includes a first plurality of ions that impact the sputtering target to generate sufficient thermal energy in the sputtering target to cause a sputtering yield of the sputtering target to be non-linearly related to a temperature of the sputtering target.

1 - 30 . (canceled)  
     
     
         31 . A sputtering source comprising: 
 a) a cathode assembly that is positioned adjacent to an anode, the cathode assembly including a sputtering target;    b) an ionization source that generates a weakly-ionized plasma from a feed gas proximate to the anode and the cathode assembly; and    c) a power supply that generates a voltage pulse between the anode and the cathode assembly that creates a strongly-ionized plasma from the weakly-ionized plasma, at least one of an amplitude, a rise time, and a duration of the voltage pulse being chosen to increase a density of ions in the strongly-ionized plasma enough to generate sufficient thermal energy from ion bombardment of a surface layer of the sputtering target to cause a sputtering yield to be related to a temperature of the sputtering target.    
     
     
         32 . The sputtering source of  claim 31  wherein the sputtering yield is related to a temperature of a surface of the sputtering target.  
     
     
         33 . The sputtering source of  claim 31  wherein the sputtering yield is linearly related to the temperature of the sputtering target.  
     
     
         34 . The sputtering source of  claim 31  further comprising a gas flow controller that controls a flow of the feed gas so that the feed gas diffuses the strongly-ionized plasma.  
     
     
         35 . The sputtering source of  claim 34  wherein the controller controls the flow of the feed gas to allow additional power to be absorbed by the strongly ionized plasma, thereby generating additional thermal energy in the sputtering target.  
     
     
         36 . The sputtering source of  claim 31  wherein the thermal energy generated in the sputtering target from ion bombardment does not substantially increase an average temperature of the sputtering target.  
     
     
         37 . The sputtering source of  claim 31  further comprising a magnet that is positioned to generate a magnetic field proximate to the weakly-ionized plasma, the magnetic field substantially trapping electrons in the weakly-ionized plasma proximate to the sputtering target.  
     
     
         38 . The sputtering source of  claim 31  wherein the voltage pulse generated between the anode and the cathode assembly excites atoms in the weakly-ionized plasma and generates secondary electrons from the cathode assembly, the secondary electrons ionizing a portion of the excited atoms, thereby creating the strongly-ionized plasma.  
     
     
         39 . The sputtering source of  claim 31  wherein the power supply generates a constant power.  
     
     
         40 . The sputtering source of  claim 31  wherein the power supply generates a constant voltage.  
     
     
         41 . The sputtering source of  claim 31  wherein the ionization source is chosen from the group comprising an electrode coupled to a DC power supply, an electrode coupled to an AC power supply, a UV source, an X-ray source, an electron beam source, an ion beam source, an inductively coupled plasma source, a capacitively coupled plasma source, and a microwave plasma source.  
     
     
         42 . The sputtering source of  claim 31  wherein a rise time of the voltage pulse is chosen to increase an ionization rate of the strongly-ionized plasma.  
     
     
         43 . The sputtering source of  claim 31  wherein a presence of weakly-ionized plasma reduces the probability of developing an electrical breakdown condition when the power supply generates the voltage pulse between the anode and the cathode assembly.  
     
     
         44 . The sputtering source of  claim 31  wherein the strongly-ionized plasma is substantially non-uniform proximate to the cathode assembly.  
     
     
         45 . The sputtering source of  claim 31  wherein a distance between the anode and the cathode assembly is chosen to increase an ionization rate of strongly-ionized plasma.  
     
     
         46 . The sputtering source of  claim 31  wherein the rise time of the voltage pulse is in the range of approximately 0.1V/μsec to 100V/μsec.  
     
     
         47 . The sputtering source of  claim 31  wherein the discharge voltage for the weakly ionized plasma is in the range of approximately 100V to 1,000V.  
     
     
         48 . The sputtering source of  claim 31  wherein the amplitude of the voltage pulse is in the range of approximately 200V to 30,000V.  
     
     
         49 . The sputtering source of  claim 31  wherein a pulse width of the voltage pulse is in the range of approximately 0.1 μsec to 100 sec.  
     
     
         50 . A method for high deposition rate sputtering, the method comprising: 
 a) ionizing a feed gas to generate a weakly-ionized plasma proximate to a cathode assembly that comprises a sputtering target; and    b) applying a voltage pulse to the cathode assembly to generate a strongly-ionized plasma from the weakly-ionized plasma, at least one of an amplitude, a rise time, and a duration of the voltage pulse being chosen so that ions in the strongly-ionized plasma bombard a surface layer of the sputtering target to generate sufficient thermal energy in the surface layer of the sputtering target to cause a sputtering yield to be related to a temperature of the sputtering target.    
     
     
         51 . The method of  claim 50  wherein the sputtering yield is linearly related to the temperature of the sputtering target.  
     
     
         52 . The method of  claim 50  wherein the sputtering yield is non-linearly related to the temperature of the sputtering target.  
     
     
         53 . The method of  claim 50  wherein the rise time of the voltage pulse is in the range of approximately 0.1V/μsec to 100V/μsec.  
     
     
         54 . The method of  claim 50  wherein the amplitude of the voltage pulse is in the range of approximately 200V to 10,000V.  
     
     
         55 . The method of  claim 50  wherein a pulse width of the voltage pulse is in the range of approximately 0.1 μsec to 100 sec.  
     
     
         56 . The method of  claim 50  further comprising generating a magnetic field proximate to the sputtering target, the magnetic field trapping electrons proximate to the sputtering target.  
     
     
         57 . The method of  claim 50  wherein the applying the voltage pulse to the cathode assembly generates excited atoms in the weakly-ionized plasma and generates secondary electrons from the sputtering target, the secondary electrons ionizing a portion of excited atoms, thereby creating the strongly-ionized plasma.  
     
     
         58 . The method of  claim 50  further comprising diffusing the weakly-ionized plasma with a volume of the feed gas while ionizing the volume of the feed gas to create additional weakly-ionized plasma.  
     
     
         59 . The method of  claim 50  further comprising exchanging a volume of feed gas to diffuse the strongly-ionized plasma while applying the voltage pulse to the cathode assembly to generate additional strongly-ionized plasma from the volume of the feed gas.  
     
     
         60 . The method of  claim 50  wherein a presence of weakly-ionized plasma reduces the probability of developing an electrical breakdown condition when the power supply generates a voltage pulse between cathode and anode assembly.  
     
     
         61 . The method of  claim 50  wherein the ionizing the feed gas comprises exposing the feed gas to one of a static electric field, an AC electric field, a quasi-static electric field, a pulsed electric field, UV radiation, X-ray radiation, an electron beam, and an ion beam.  
     
     
         62 . The method of  claim 50  wherein the ions in the strongly-ionized plasma cause a surface layer of the sputtering target to evaporate during the applied voltage pulse.