High-power pulsed magnetically enhanced plasma processing

Abstract

Magnetically enhanced plasma processing methods and apparatus are described. A magnetically enhanced plasma processing apparatus according to the present invention includes an anode and a cathode that is positioned adjacent to the anode. An ionization source generates a weakly-ionized plasma proximate to the cathode. A magnet is positioned to generate a magnetic field proximate to the weakly-ionized plasma. The magnetic field substantially traps electrons in the weakly-ionized plasma proximate to the cathode. A power supply produces an electric field in a gap between the anode and the cathode. The electric field generates excited atoms in the weakly-ionized plasma and generates secondary electrons from the cathode. The secondary electrons ionize the excited atoms, thereby creating a strongly-ionized plasma. A voltage supply applies a bias voltage to a substrate that is positioned proximate to the cathode that causes ions in the plurality of ions to impact a surface of the substrate in a manner that causes etching of the surface of the substrate

1 - 37 . (canceled)  
     
     
         38 . A magnetically enhanced plasma source comprising: 
 a) an anode;    b) a cathode that is positioned adjacent to the anode;    c) an ionization source that generates a weakly-ionized plasma;    d) 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 cathode; and    e) a power supply that produces an electric field across the anode and the cathode, the electric field generating at least one of excited atoms and excited molecules in the weakly-ionized plasma and generating secondary electrons from the cathode, the secondary electrons ionizing the excited atoms, thereby creating a strongly-ionized plasma comprising a plurality of ions.    
     
     
         39 . The plasma source of  claim 38  further comprising a voltage supply that applies a bias voltage to a substrate that is positioned proximate to the cathode, the bias voltage causing ions in the plurality of ions to impact a surface of the substrate in a manner that processes the surface of the substrate:  
     
     
         40 . The plasma source of  claim 39  wherein the bias voltage is selected to control ion energy of the ions in the plurality of ions that impact the surface of the substrate.  
     
     
         41 . The plasma source of  claim 38  wherein the electric field comprises a quasi-static electric field.  
     
     
         42 . The plasma source of  claim 38  wherein the electric field comprises a pulsed electric field.  
     
     
         43 . The plasma source of  claim 38  wherein a rise time of the electric field is chosen to increase an ionization rate of at least one of the excited atoms and the excited molecules in the weakly-ionized plasma.  
     
     
         44 . The plasma source of  claim 38  wherein the weakly-ionized plasma reduces the probability of developing an electrical breakdown condition between the anode and the cathode.  
     
     
         45 . The plasma source of  claim 38  wherein a volume between the anode and the cathode is chosen to increase an ionization rate of at least one of the excited atoms and the excited molecules in the weakly-ionized plasma.  
     
     
         46 . The plasma source of  claim 38  wherein the ionization source is chosen from the group comprising 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, a microwave plasma source, an electrode, a DC power supply, and an AC power supply.  
     
     
         47 . The plasma source of  claim 38  wherein the power supply generates an electrical pulse that produces the electric field across the anode and the cathode.  
     
     
         48 . The plasma source of  claim 38  wherein the electric field generates ions and at least one of excited atoms and excited molecules in the weakly-ionized plasma and generates secondary electrons from the cathode, the secondary electrons ionizing the at least one of the excited atoms, the excited modules, neutral atoms and neural molecules, thereby creating the strongly-ionized plasma.  
     
     
         49 . The plasma source of  claim 38  wherein the electric field generates a discharge voltage that results in a low probability of sputtering material from the cathode.  
     
     
         50 . A magnetically enhanced reactive ion etching plasma processing apparatus comprising: 
 a) an anode;    b) a cathode that is positioned adjacent to the anode;    c) an ionization source that generates a weakly-ionized plasma from a volume of feed gas that includes at least one reactive gas;    d) 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 cathode;    e) a power supply that produces an electric field across the anode and the cathode, the electric field generating excited molecules in the weakly-ionized plasma and generating secondary electrons from the cathode, the secondary electrons ionizing at least a portion of the excited molecules, thereby creating a strongly-ionized plasma comprising a plurality of reactive ions; and    f) a voltage supply that applies a bias voltage to a substrate that is positioned proximate to the cathode, the bias voltage causing ions in the plurality of ions to impact a surface of the substrate in a manner that causes reactive ion etching of the surface of the substrate.    
     
     
         51 . The apparatus of  claim 50  wherein the electric field comprises a quasi-static electric field.  
     
     
         52 . The apparatus of  claim 50  wherein the electric field comprises a pulsed electric field.  
     
     
         53 . The apparatus of  claim 50  wherein a rise time of the electric field is chosen to increase an ionization rate of the excited molecules in the weakly-ionized plasma.  
     
     
         54 . The apparatus of  claim 50  wherein a rise time of the electric field is chosen to increase an etch rate of the surface of the substrate.  
     
     
         55 . The apparatus of  claim 50  wherein the weakly-ionized plasma reduces the probability of developing an electrical breakdown condition between the anode and the cathode.  
     
     
         56 . The apparatus of  claim 50  wherein a magnitude of at least one of the magnetic field, the electric field, and the bias voltage are selected so that the ions in the plurality of ions impact the surface of the substrate and cause substantially uniform etching of the surface of the substrate.  
     
     
         57 . The apparatus of  claim 50  wherein a magnitude of at least one of the magnetic field, the electric field, and the bias voltage are selected so that the ions in the plurality of ions impact the surface of the substrate and cause anisotropic etching of the surface of the substrate.  
     
     
         58 . The apparatus of  claim 50  wherein a volume between the anode and the cathode is chosen to increase an ionization rate of the excited molecules in the weakly-ionized plasma.  
     
     
         59 . The apparatus of  claim 50  wherein the ionization source is chosen from the group comprising 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, a microwave plasma source, an electrode, a DC power supply, and an AC power supply.  
     
     
         60 . The apparatus of  claim 50  wherein the power supply generates an electrical pulse that produces the electric field across the anode and the cathode.  
     
     
         61 . The apparatus of  claim 50  wherein at least one of a pulse amplitude and a pulse width of the electrical pulse is selected to increase a rate of etching of the surface of the substrate.  
     
     
         62 . The apparatus of  claim 50  wherein the electric field generates ions and excited molecules in the weakly-ionized plasma and generates secondary electrons from the cathode, the secondary electrons ionizing the excited molecules and neural molecules, thereby creating the strongly-ionized plasma.  
     
     
         63 . The apparatus of  claim 50  wherein the electric field generates a discharge voltage that results in a low probability of sputtering material from the cathode.