Apparatus and method of gas injection sequencing

Abstract

An apparatus and method for gas injection sequencing in order to increase the gas injection total pressure while satisfying an upper limit to the process gas flow rate, thereby achieving gas flow uniformity during a sequence cycle and employing practical orifice configurations. The gas injection system includes a gas injection electrode having a plurality of regions, through which process gas flows into the process chamber. The gas injection system further includes a plurality of gas injection plenums, each independently coupled to one of the aforesaid regions and a plurality of gas valves having an inlet end and an outlet end, where the outlet end is independently coupled to one of the aforesaid plurality of gas injection plenums. The gas injection system includes a controller coupled to the plurality of gas valves for sequencing the flow of process gas through the aforesaid plurality of regions.

1 . A plasma processing device comprising a processing surface and a gas injection system, the gas injection system comprising: 
 a plurality of gas valves having an inlet configured to receive a process gas and an outlet;    a process chamber;    a gas injection electrode provided within the process chamber;    a plurality of gas injection plenums provided on the gas injection electrode, the plurality of gas injection plenums being independently coupled to the outlet of a respective one of the plurality of gas valves;    a plurality of regions provided on the gas injection electrode, each region of the plurality of regions includes at least one gas injection orifice coupled to a respective one of the plurality of gas injection plenums; and    a controller coupled to the plurality of gas valves for sequencing a flow of process gas through the plurality of regions into the process chamber.    
     
     
         2 . The apparatus according to  claim 1 , wherein at least one region of the plurality of regions is substantially parallel to the processing surface, and wherein the at least one gas injection orifice of the at least one region is configured to discharge process gas into the process chamber in a direction substantially normal to the processing surface.  
     
     
         3 . The apparatus according to  claim 1 , wherein the plurality of regions are substantially parallel to the processing surface, and wherein the at least one gas injection orifice of the plurality of regions is configured to discharge process gas into the process chamber in a direction substantially normal to the processing surface.  
     
     
         4 . The apparatus according to  claim 1 , further comprising: 
 a common gas line; and    a gas supply system,    wherein the inlet of each of the plurality of the gas valves is coupled to the common gas line, and    wherein the common gas line is coupled to the gas supply system.    
     
     
         5 . The apparatus according to  claim 1 , further comprising: 
 a plurality of gas lines; and    a plurality of gas supplies,    wherein the inlet of at least one of the plurality of gas valves is independently coupled to one of the plurality of gas lines, and    wherein the plurality of gas lines are coupled to the plurality of gas supplies.    
     
     
         6 . The apparatus according to  claim 1 , wherein the at least one gas injection orifice is substantially cylindrical.  
     
     
         7 . The apparatus according to  claim 6 , wherein the at least one gas injection orifice is a sonic orifice.  
     
     
         8 . The apparatus according to  claim 6 , wherein the at least one gas injection orifice has a length between 0.025 mm and 20 mm, and a diameter between 0.025 mm and 2 mm.  
     
     
         9 . The apparatus according to  claim 1 , wherein the at least one gas injection orifice comprises: 
 a throat section having a substantially cylindrical cross section and a throat diameter;    a divergent section connected to the throat section, the divergent section having an inlet with an inlet diameter and an exit with an exit diameter, the exit diameter being at least as large as the inlet diameter,    wherein the inlet diameter of the divergent section is equivalent to the throat diameter of throat section.    
     
     
         10 . The apparatus according to  claim 9 , wherein the divergent section is conically divergent.  
     
     
         11 . The apparatus according to  claim 10 , wherein the divergent section has a half-angle that is at most 18 degrees.  
     
     
         12 . The apparatus according to  claim 10  wherein the divergent section has a half-angle that is between 12 degrees and 18 degrees.  
     
     
         13 . The apparatus according to  claim 9 , wherein the divergent section includes a concave wall, wherein the concave wall extends from the inlet to the exit.  
     
     
         14 . The apparatus according to  claim 9  wherein the divergent section is a minimum-length nozzle.  
     
     
         15 . The apparatus according to  claim 9  wherein the divergent section is a perfect nozzle.  
     
     
         16 . A gas injection system for a plasma processing device, the gas injection system comprising: 
 a first gas valve having an inlet configured to receive a process gas and an outlet;    a second gas valve having an inlet configured to receive a process gas and an outlet;    a gas injection electrode provided within a process chamber;    a first gas injection plenum provided on the gas injection electrode, the first gas injection plenum being coupled to the outlet of the first gas valve;    a second gas injection plenum provided on the gas injection electrode, the second gas injection plenum being coupled to the outlet of the second gas valve;    a first gas injection orifice provided on the gas injection electrode, the first gas injection orifice being coupled to the first gas injection plenum;    a second gas injection orifice provided on the gas injection electrode, the second gas injection orifice being coupled to the second gas injection plenum; and    a controller coupled to the first gas valve and the second gas valve for sequencing a flow of process gas through the first gas injection plenum and the second gas injection plenum into the process chamber.    
     
     
         17 . A method for supplying at least one process gas to a plasma processing device using a gas injection system, the method comprising the steps of: 
 (i) cyclically providing the at least one process gas at a first gas flow rate for a first period of time within the plasma processing device at a first region of the gas injection system;    (ii) cyclically providing the at least one process gas at a second gas flow rate for a second period of time within the plasma processing device at a second region of the gas injection system; and    (iii) performing steps (i) and (ii) for a third period of time, wherein the first gas flow rate and the second gas flow rate are maintained substantially constant during the third period of time.    
     
     
         18 . The method according to  claim 17 , wherein a first process gas is provided in step (i) and a second process gas is provided in step (ii), and wherein the first process gas is different from the second process gas.  
     
     
         19 . The method according to  claim 17 , further comprising the steps of: 
 (iv) cyclically providing the at least one process gas at a third gas flow rate for a fourth period of time within the plasma processing device at a third region of the gas injection system; and    (v) performing step (iv) for the third period of time.    
     
     
         20 . The method according to  claim 19 , wherein the a first process gas is provided in step (i), a second process gas is provided in step (ii) and a third process gas is provided in step (iv), and wherein the first process gas, the second process gas and the third process gas are different.  
     
     
         21 . A method according to  claim 17  wherein the first period of time and the second period of time range between 1 and 5 seconds.  
     
     
         22 . A method for supplying at least one process gas to a plasma processing device using a gas injection system, the method comprising the steps of: 
 (i) cyclically providing the at least one process gas at a first gas flow rate for a first period of time within the plasma processing device at a first region of the gas injection system;    (ii) cyclically providing the at least one process gas at a second gas flow rate for a second period of time within the plasma processing device at a second region of the gas injection system; and    (iii) performing steps (i) and (ii) for a third period of time, wherein a gas mass flux into the plasma processing device is maintained substantially constant during the third period of time.    
     
     
         23 . The method according to  claim 22 , wherein a first process gas is provided in step (i) and a second process gas is provided in step (ii), and wherein the first process gas is different from the second process gas.  
     
     
         24 . The method according to  claim 22 , further comprising the steps of: 
 (iv) cyclically providing the at least one process gas at a third gas flow rate for a fourth period of time within the plasma processing device at a third region of the gas injection system; and    (v) performing step (iv) for the third period of time.    
     
     
         25 . The method according to  claim 24 , wherein the a first process gas is provided in step (i), a second process gas is provided in step (ii) and a third process gas is provided in step (iv), and wherein the first process gas, the second process gas and the third process gas are different.  
     
     
         26 . The method according to  claim 22  wherein the first period of time and the second period of time range between 1 and 5 seconds.  
     
     
         27 . A method for supplying at least one process gas to a plasma processing device using a gas injection system, the method comprising the steps of: 
 (i) cyclically providing the at least one process gas at a first gas flow rate for a first period of time within the plasma processing device at a first region of the gas injection system;    (ii) cyclically providing the at least one process gas at a second gas flow rate for a second period of time within the plasma processing device at a second region of the gas injection system; and    (iii) performing steps (i) and (ii) for a third period of time, wherein a start of the second period of time overlaps an end of the first period of time.    
     
     
         28 . The method according to  claim 27 , wherein a first process gas is provided in step (i) and a second process gas is provided in step (ii), and wherein the first process gas is different from the second process gas.  
     
     
         29 . The method according to  claim 27 , further comprising the steps of: 
 (iv) cyclically providing the at least one process gas at a third gas flow rate for a fourth period of time within the plasma processing device at a third region of the gas injection system; and    (v) performing step (iv) for the third period of time.    
     
     
         30 . The method according to  claim 29 , wherein the a first process gas is provided in step (i), a second process gas is provided in step (ii) and a third process gas is provided in step (iv), and wherein the first process gas, the second process gas and the third process gas are different.  
     
     
         31 . The method according to  claim 27 , wherein the first period of time and the second period of time range between 1 and 5 seconds.  
     
     
         32 . The method according to  claim 27 , wherein the overlap of the first period of time and the second period of time ranges between 0.1 and 1 second.