Plasma etching apparatus

Abstract

A plasma etching apparatus includes an upper electrode and a lower electrode (susceptor) on which a semiconductor wafer is disposed, the upper and lower electrodes being arranged within a process chamber, a first high frequency power source for applying a first high frequency power having a frequency not lower than 50 MHz to the upper electrode, a second high frequency power source for applying a high frequency power having a frequency not lower than 2 MHz and lower than the frequency of the first high frequency power to the upper and lower electrodes. The frequency of the high frequency power applied by the second high frequency source to the upper electrode is equal to that of the high frequency power applied by the second high frequency source to the lower electrode, and the high frequency power applied by the second high frequency source to the upper electrode has a reverse phase relative to the high frequency power applied by the second high frequency source to the lower electrode. The inner space of the process chamber is maintained at a predetermined reduced pressure state, and supplied with an etching gas. The high frequency power applied from the second high frequency source to the upper electrode permits increasing the thickness of the plasma sheath formed on the upper electrode.

1 - 16 . (canceled)  
   
   
       17 . A process apparatus comprising: 
 a process chamber in which a target object to be processed is housed;    an upper electrode provided in the process chamber;    a lower electrode provided in the process chamber to face the upper electrode, and on which the target object is mounted;    a first high frequency oscillator connected to the upper electrode to supply a first high frequency power to the upper electrode;    a second high frequency oscillator connected to the upper and lower electrodes to supply a second high frequency power to the upper and lower electrodes; and    a phase shift circuit provided between the second high frequency oscillator and one of the electrodes to adjust a phase of the second high frequency power supplied to said one electrode.    
   
   
       18 . The process apparatus according to  claim 17 , wherein the phase shift circuit is connected between the second high frequency oscillator and the lower electrode to adjust the phase of the second high frequency oscillator power supplied to the lower electrode.  
   
   
       19 . The processing apparatus according to  claim 17 , wherein the phase shift circuit shifts the phase of the second high frequency power supplied to said one electrode, by a range of 180+/−45 degrees.  
   
   
       20 . The processing apparatus according to  claim 18 , wherein the phase shift circuit shifts the phase of the second high frequency power supplied to said one electrode by 180 degrees.  
   
   
       21 . The processing apparatus according to  claim 18 , wherein the phase shift circuit shifts the phase of the second high frequency power supplied to the lower electrode, by a range of 180+/−45 degrees.  
   
   
       22 . The processing apparatus according to  claim 21 , wherein the phase shift circuit shifts the phase of the second high frequency power supplied to the lower electrode by 180 degrees.  
   
   
       23 . The processing apparatus according to  claim 17 , further comprising a first amplifier, a first matching device, and a first low pass filter connected between the second high frequency oscillator and the upper electrode, and a second amplifier, a second matching device, and a second low pass filter connected between the second high frequency oscillator and the lower electrode.  
   
   
       24 . The processing apparatus according to  claim 17 , wherein a frequency of the first high frequency power is higher than that of the second high frequency power.