Ex Parte Signorini - Page 5

                Appeal 2007-1097                                                                             
                Application 10/230,593                                                                       
           1          Gupta indicates that the source of the oxygen plasma is preferably                     
           2    molecular oxygen, O2, and reference to “O2 plasma” is directed to this                       
           3    embodiment.  Gupta 7:24-27.                                                                  
           4          Nevertheless, Gupta discloses that alternative sources of oxygen such                  
           5    as CO2, NO, and N2O may be suitably employed as a source of oxygen                           
           6    plasma in the process of the present invention.  Gupta 9:17-21.                              
           7          To minimize the effect of atomic oxygen near the reaction site,                        
           8    scavenger atoms are provided in the Gupta process.  The scavenger atoms                      
           9    comprise free radicals which are capable of sweeping and/or capturing                        
          10    atomic oxygen.  Gupta 7:50-54.                                                               
          11          Preferably, the scavenger atoms are provided by including a nitrogen                   
          12    plasma in the plasma etchant.  Preferably, the nitrogen plasma is provided by                
          13    N2.  Gupta 7:64-67.                                                                          
          14          Additionally, a significant amount of helium is added to the mixture                   
          15    of nitrogen and oxygen.  Gupta 8:12-13.                                                      
          16          Helium is said to minimize thermal degradation of the photoresist                      
          17    layer.  Gupta 8:14-17.                                                                       
          18          Without helium or other inert gases, melting of the photoresist layer is               
          19    said to be a concern, and in some cases, the etching process must be                         
          20    periodically stopped to allow for cooling.  Gupta 8:17-19.                                   
          21          In Example 2, a mixture of oxygen and nitrogen without helium is                       
          22    said to have provided an increased etch rate.  Gupta 11:26-47.                               
          23          Adding helium in Example 2 is said to have reduced the residence                       
          24    time of active oxygen species.  Gupta 11:48-53.                                              




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