Method and apparatus for high aspect ratio dielectric etch

Abstract

An apparatus for etching high aspect ratio features is provided. A plasma processing chamber is provided, comprising a chamber wall forming a plasma processing chamber enclosure, a lower electrode, an upper electrode, a gas inlet, and a gas outlet. A high frequency radio frequency (RF) power source is electrically connected to at least one of the upper electrode or lower electrode. A bias power system is electrically connected to both the upper electrode and the lower electrode, wherein the bias power system is able to provide a bias to the upper and lower electrodes with a magnitude of at least 500 volts, and wherein the bias to the lower electrode is pulsed to intermittently. A gas source is in fluid connection with the gas inlet. A controller is controllably connected to the gas source, the high frequency RF power source, and the bias power system.

What is claimed is: 
     
         1 . An apparatus for etching high aspect ratio features in a dielectric layer, comprising:
 a plasma processing chamber, comprising:
 a chamber wall forming a plasma processing chamber enclosure; 
 a lower electrode for providing power to the plasma processing chamber enclosure over which the substrate is supported; 
 an upper electrode for providing power to the plasma processing chamber enclosure spaced apart above the lower electrode; 
 a gas inlet for providing gas into the plasma processing chamber enclosure; and 
 a gas outlet for exhausting gas from the plasma processing chamber enclosure; 
   a high frequency radio frequency (RF) power source, electrically connected to at least one of the upper electrode or lower electrode;   a bias power system electrically connected to both the upper electrode and the lower electrode, wherein the bias power system is able to provide a bias to the upper and lower electrodes with a magnitude of at least 500 volts, and wherein the bias to the upper electrode creates secondary electrons and wherein the bias to the lower electrode is pulsed to intermittently collapse a generated plasma sheath with the secondary electrons;   a gas source in fluid connection with the gas inlet, comprising a dielectric etching gas source; and   a controller controllably connected to the gas source, the high frequency RF power source, and the bias power system.   
     
     
         2 . The apparatus, as recited in  claim 1 , wherein the bias power system comprises:
 a bias power source; and   a switch for alternatingly connecting the bias power source to the upper and lower electrodes.   
     
     
         3 . The apparatus, as recited in  claim 2 , wherein the bias power source is a low frequency RF power source. 
     
     
         4 . The apparatus, as recited in  claim 3 , wherein the controller comprises:
 a processor; and   computer readable media, comprising:
 computer readable code for providing dielectric etching gas from the dielectric etching gas source into the plasma processing chamber; 
 computer readable code for providing power from the high frequency RF power source to form the etching gas into an etching plasma; 
 computer readable code for switching the switch to alternatingly connect the bias power source to the upper and lower electrodes. 
   
     
     
         5 . The apparatus, as recited in  claim 4 , wherein the computer readable code for switching the switch, performs the switching at a frequency of between 10 Hz to 100 kHz. 
     
     
         6 . The apparatus, as recited in  claim 1 , wherein the controller comprises:
 a processor; and   computer readable media, comprising:
 computer readable code for providing dielectric etching gas from the dielectric etching gas source into the plasma processing chamber; 
 computer readable code for providing power from the high frequency RF power source to form the etching gas into a etching plasma; 
 computer readable code for pulsing the bias to the lower electrode. 
   
     
     
         7 . The apparatus, as recited in  claim 6 , wherein the computer readable code for providing the pulsed bias power to the lower electrode, provides the pulsed bias power at a frequency of between 10 Hz to 100 kHz. 
     
     
         8 . The apparatus, as recited in  claim 1 , wherein the bias to the upper electrode is pulsed at a frequency equal to a frequency of pulsed bias power to the lower electrode. 
     
     
         9 . The apparatus, as recited in  claim 1 , wherein the bias power system, comprises:
 a first bias source electrically connected to the upper electrode;   a first pulse source electrically connected to the first bias source;   a second bias source electrically connected to the lower electrode; and   a second pulse source electrically connected to the second bias source.   
     
     
         10 . The apparatus, as recited in  claim 1 , wherein the upper electrode and lower electrode are parallel plate electrodes. 
     
     
         11 . An apparatus for etching high aspect ratio features in a dielectric layer, comprising:
 a plasma processing chamber, comprising:
 a chamber wall forming a plasma processing chamber enclosure; 
 a lower electrode for providing power to the plasma processing chamber enclosure over which the substrate is supported; 
 an upper electrode for providing power to the plasma processing chamber enclosure spaced apart above the lower electrode; 
 a gas inlet for providing gas into the plasma processing chamber enclosure; and 
 a gas outlet for exhausting gas from the plasma processing chamber enclosure; 
   a high frequency radio frequency (RF) power source, electrically connected to at least one of the upper electrode or lower electrode;   a bias power system electrically connected to both the upper electrode and the lower electrode, comprising:
 a low frequency RF source; and 
 a switch electrically connected between the low frequency RF source and the upper electrode and lower electrode for alternatingly switching between the upper electrode and lower electrode; 
   a gas source in fluid connection with the gas inlet, comprising a dielectric etching gas source; and   a controller controllably connected to the gas source, the high frequency RF power source, and the bias power system.   
     
     
         12 . The apparatus, as recited in  claim 11 , wherein the controller comprises:
 a processor; and   computer readable media, comprising:
 computer readable code for providing dielectric etching gas from the dielectric etching gas source into the plasma processing chamber; 
 computer readable code for providing power from the high frequency RF power source to form the etching gas into a etching plasma; 
 computer readable code for switching the switch to alternatingly connect the bias power source to the upper and lower electrodes. 
   
     
     
         13 . The apparatus, as recited in  claim 11 , wherein the computer readable code for switching the switch performs the switching at a frequency of between 10 Hz to 100 kHz. 
     
     
         14 . The apparatus, as recited in  claim 11 , wherein the upper electrode and lower electrode are parallel plate electrodes. 
     
     
         15 . The apparatus, as recited in  claim 1 , wherein the bias to the upper electrode of at least 500 volts provides the created secondary electrons with enough energy to pass through a plasma sheath to vias, wherein a positive charge at the bottom of the vias accelerates the secondary electrons to the bottom of the vias. 
     
     
         16 . The apparatus, as recited in  claim 1 , wherein the high frequency radio frequency has a frequency of at least 10 MHz 
     
     
         17 . The apparatus, as recited in  claim 3 , wherein the low frequency radio frequency has a frequency less than 10 MHz. 
     
     
         18 . The apparatus, as recited in  claim 11 , wherein the high frequency radio frequency has a frequency of at least 10 MHz.