Plasma etching method and plasma etching unit

Abstract

The present invention is a plasma etching method including: an arranging step of arranging a pair of electrodes oppositely in a chamber and making one of the electrodes support a substrate to be processed in such a manner that the substrate is arranged between the electrodes, the substrate having a silicon film and an inorganic-material film adjacent to the silicon film; and an etching step of applying a high-frequency electric power to at least one of the electrodes to form a high-frequency electric field between the pair of the electrodes, supplying a process gas into the chamber to form a plasma of the process gas by means of the electric field, and selectively plasma-etching the silicon film of the substrate by means of the plasma; wherein a frequency of the high-frequency electric power applied to the at least one of the electrodes is 50 to 150 MHz in the etching step.

1 . A plasma etching method comprising: 
 an arranging step of arranging a pair of electrodes oppositely in a chamber and making one of the electrodes support a substrate to be processed in such a manner that the substrate is arranged between the electrodes, the substrate having a silicon film and an inorganic-material film adjacent to the silicon film, and    an etching step of applying a high-frequency electric power to at least one of the electrodes to form a high-frequency electric field between the pair of the electrodes, supplying a process gas into the chamber to form a plasma of the process gas by means of the electric field, and selectively plasma-etching the silicon film of the substrate by means of the plasma,    wherein, in the etching step, a frequency of the high-frequency electric power applied to the at least one of the electrodes is 50 to 150 MHz and a pressure in the chamber is not higher than 13.3 Pa.    
   
   
       2 . A plasma etching method according to  claim 1 , wherein 
 the frequency of the high-frequency electric power applied to the at least one of the electrodes is 100 MHz in the etching step.    
   
   
       3 . A plasma etching method according to  claim 1 , wherein 
 in the etching step, power density of the high-frequency electric power is 0.15 to 5 W/cm 2 .    
   
   
       4 . A plasma etching method according to  claim 1 , wherein 
 in the etching step, plasma density in the chamber is 5×10 9  to 2×10 10  cm −3 .    
   
   
       5 . A plasma etching method according to  claim 1 , wherein 
 the inorganic-material film comprises at least one of a silicon oxide, a silicon nitride, a silicon oxinitride, and a silicon carbide.    
   
   
       6 . A plasma etching method according to  claim 1 , wherein 
 in the etching step, the high-frequency electric power is applied to an electrode supporting the substrate to be processed.    
   
   
       7 . A plasma etching method according to  claim 6 , wherein 
 in the etching step, a second high-frequency electric power of 3.2 MHz to 13.56 MHz is applied to the electrode supporting the substrate to be processed, the second high-frequency electric power being overlapped with the high-frequency electric power.    
   
   
       8 . A plasma etching method comprising: 
 an arranging step of arranging a pair of electrodes oppositely in a chamber and making one of the electrodes support a substrate to be processed in such a manner that the substrate is arranged between the electrodes, the substrate having a silicon film and an inorganic-material film adjacent to the silicon film, and    an etching step of applying a high-frequency electric power to at least one of the electrodes to form a high-frequency electric field between the pair of the electrodes, supplying a process gas into the chamber to form a plasma of the process gas by means of the electric field, and selectively plasma-etching the silicon film of the substrate by means of the plasma,    wherein    in the etching step, a frequency of the high-frequency electric power applied to the at least one of the electrodes is 50 to 150 MHz,    in the etching step, the high-frequency electric power is applied to an electrode supporting the substrate to be processed,    in the etching step, a second high-frequency electric power is applied to the electrode supporting the substrate to be processed, the second high-frequency electric power being overlapped with the high-frequency electric power, and    a frequency of the second high-frequency electric power is 13.56 MHz.    
   
   
       9 . A plasma etching method according to  claim 8 , wherein 
 power density of the second high-frequency electric power is not higher than 0.64 W/cm 2 .    
   
   
       10 . A plasma etching method according to  claim 7 , wherein 
 in the etching step, a self-bias electric voltage of the electrode supporting the substrate to be processed is not higher than 200 V.    
   
   
       11 . A plasma etching method according to  claim 1 , wherein 
 a distance between the pair of electrodes is shorter than 50 mm.    
   
   
       12 . A plasma etching method comprising: 
 an arranging step of arranging a pair of electrodes oppositely in a chamber and making one of the electrodes support a substrate to be processed in such a manner that the substrate is arranged between the electrodes, the substrate having a silicon film and an inorganic-material film adjacent to the silicon film, and    an etching step of applying a high-frequency electric power to at least one of the electrodes to form a high-frequency electric field between the pair of the electrodes, supplying a process gas into the chamber to form a plasma of the process gas by means of the electric field, and selectively plasma-etching the silicon film of the substrate by means of the plasma,    wherein    in the etching step, a frequency of the high-frequency electric power applied to the at least one of the electrodes is 50 to 150 MHz, and    in the etching step, a magnetic field is formed around a plasma region between the pair of electrodes to achieve a plasma confining effect.    
   
   
       13 . A plasma etching method according to  claim 12 , wherein 
 strength of the magnetic field formed around the plasma region between the pair of electrodes is 0.03 to 0.045 T (300 to 450 Gauss).    
   
   
       14 . A plasma etching method according to  claim 13 , wherein 
 when the magnetic field is formed around the plasma region between the pair of electrodes, strength of the magnetic field on a focus ring provided around the substrate to be processed is not lower than 0.001 T (10 Gauss) and strength of the magnetic field on the substrate to be processed is not higher than 0.001 T.    
   
   
       15 . A plasma etching method according to  claim 1 , wherein 
 the silicon film comprises poly-silicon.    
   
   
       16 . A plasma etching method comprising: 
 an arranging step of arranging a pair of electrodes oppositely in a chamber and making one of the electrodes support a substrate to be processed in such a manner that the substrate is arranged between the electrodes, the substrate having a silicon film and an inorganic-material film adjacent to the silicon film, and    an etching step of applying a high-frequency electric power to at least one of the electrodes to form a high-frequency electric field between the pair of the electrodes, supplying a process gas into the chamber to form a plasma of the process gas by means of the electric field, and selectively plasma-etching the silicon film of the substrate by means of the plasma,    wherein in the etching step, the process gas includes at least one of an HBr gas and a Cl 2  gas, plasma density in the chamber is 5×10 9  to 2×10 10  cm −3 , a self-bias electric voltage of the electrode supporting the substrate to be processed is not higher than 200 V, and a pressure in the chamber is not higher than 13.3 Pa.    
   
   
       17 . A plasma-etching-condition confirming method comprising: 
 an arranging step of arranging a pair of electrodes oppositely in a chamber and making one of the electrodes support a substrate to be processed in such a manner that the substrate is arranged between the electrodes, the substrate having a silicon film and an inorganic-material film adjacent to the silicon film, and    a plasma-forming step of applying a high-frequency electric power to at least one of the electrodes to form a high-frequency electric field between the pair of the electrodes, and supplying an Ar gas into the chamber to form a plasma of the Ar gas by means of the electric field,    wherein in the plasma-forming step, a confirming step is carried out to confirm that plasma density in the chamber is not lower than 1×10 10  cm −3  and that a self-bias electric voltage of the electrode supporting the substrate to be processed is not higher than 100 V.    
   
   
       18 . A plasma etching unit comprising: 
 a chamber configured to contain a substrate to be processed having a silicon film and an inorganic-material film adjacent to the silicon film,    a pair of electrodes arranged in the chamber, one of the pair of electrodes being configured to support the substrate to be processed,    a process-gas supplying system configured to supply a process gas into the chamber,    a gas-discharging system configured to discharge a gas in the chamber, and    a high-frequency electric power source configured to supply a high-frequency electric power for forming a plasma to at least one of the electrodes,    wherein a frequency of the high-frequency electric power generated from the high-frequency electric power source is 50 to 150 MHz, and a pressure in the chamber is not higher than 13.3 Pa.    
   
   
       19 . A plasma etching unit according to  claim 18 , wherein 
 the frequency of high-frequency electric power generated from the high-frequency electric power source is 100 MHz.    
   
   
       20 . A plasma etching unit according to  claim 18 , wherein 
 power density of the high-frequency electric power is 0.15 to 5 W/cm 2 .    
   
   
       21 . A plasma etching unit according to  claim 18 , wherein 
 the high-frequency electric power is applied to an electrode supporting the substrate to be processed.    
   
   
       22 . A plasma etching unit according to  claim 21 , further comprising 
 a second high-frequency electric power source configured to apply a second high-frequency electric power of 3.2 MHz to 13.56 MHz to the electrode supporting the substrate to be processed, the second high-frequency electric power being overlapped with the high-frequency electric power.    
   
   
       23 . A plasma etching unit comprising: 
 a chamber configured to contain a substrate to be processed having a silicon film and an inorganic-material film adjacent to the silicon film,    a pair of electrodes arranged in the chamber, one of the pair of electrodes being configured to support the substrate to be processed,    a process-gas supplying system configured to supply a process gas into the chamber,    a gas-discharging system configured to discharge a gas in the chamber, and    a high-frequency electric power source configured to supply a high-frequency electric power for forming a plasma to at least one of the electrodes,    wherein a frequency of the high-frequency electric power generated from the high-frequency electric power source is 50 to 150 MHz,    the high-frequency electric power is applied to an electrode supporting the substrate to be processed,    a second high-frequency electric power source configured to apply a second high-frequency electric power to the electrode supporting the substrate to be processed is provided, the second high-frequency electric power being overlapped with the high-frequency electric power, and    a frequency of the second high-frequency electric power is 13.56 MHz.    
   
   
       24 . A plasma etching unit according to  claim 23 , wherein 
 power density of the second high-frequency electric power is not higher than 0.64 W/cm 2 .    
   
   
       25 . A plasma etching unit according to  claim 18 , wherein 
 a distance between the pair of electrodes is shorter than 50 mm.    
   
   
       26 . A plasma etching unit comprising: 
 a chamber configured to contain a substrate to be processed having a silicon film and an inorganic-material film adjacent to the silicon film,    a pair of electrodes arranged in the chamber, one of the pair of electrodes being configured to support the substrate to be processed,    a process-gas supplying system configured to supply a process gas into the chamber,    a gas-discharging system configured to discharge a gas in the chamber, and    a high-frequency electric power source configured to supply a high-frequency electric power for forming a plasma to at least one of the electrodes,    wherein a frequency of the high-frequency electric power generated from the high-frequency electric power source is 50 to 150 MHz, and    a magnetic-field forming unit configured to form a magnetic field around a plasma region between the pair of electrodes is provided, the magnetic field achieving a plasma confining effect.    
   
   
       27 . A plasma etching unit according to  claim 26 , wherein 
 strength of the magnetic field formed around the plasma region between the pair of electrodes by the magnetic-field forming unit is 0.03 to 0.045 T (300 to 450 Gauss).    
   
   
       28 . A plasma etching unit according to  claim 27 , wherein 
 a focus ring is provided around the substrate to be processed, and    when the magnetic-field forming unit forms the magnetic field around the plasma region between the pair of electrodes, strength of the magnetic field on the focus ring is not lower than 0.001 T (10 Gauss) and strength of the magnetic field on the substrate to be processed is not higher than 0.001 T.    
   
   
       29 . A plasma etching unit comprising: 
 a chamber configured to contain a substrate to be processed having a silicon film and an inorganic-material film adjacent to the silicon film,    a pair of electrodes arranged in the chamber, one of the pair of electrodes being configured to support the substrate to be processed,    a process-gas supplying system configured to supply a process gas into the chamber,    a gas-discharging system configured to discharge a gas in the chamber, and    a high-frequency electric power source configured to supply a high-frequency electric power for forming a plasma to at least one of the electrodes,    wherein when a gas including at least one of an HBr gas and a Cl 2  gas is used as the process gas, plasma density in the chamber is 5×10 9  to 2×10 10  cm −3 , a self-bias electric voltage of the electrode supporting the substrate to be processed is not higher than 200 V, and a pressure in the chamber is not higher than 13.3 Pa.    
   
   
       30 . A plasma etching unit comprising: 
 a chamber configured to contain a substrate to be processed having a silicon film and an inorganic-material film adjacent to the silicon film,    a pair of electrodes arranged in the chamber, one of the pair of electrodes being configured to support the substrate to be processed,    a process-gas supplying system configured to supply a process gas into the chamber,    a gas-discharging system configured to discharge a gas in the chamber, and    a high-frequency electric power source configured to supply a high-frequency electric power for forming a plasma to at least one of the electrodes,    wherein when an Ar gas is used as the process gas, plasma density in the chamber is not lower than 1×10 10  cm −3 , a self-bias electric voltage of the electrode supporting the substrate to be processed is not higher than 100 V, and a pressure in the chamber is not higher than 13.3 Pa.    
   
   
       31 . A plasma etching method according to  claim 1 , wherein 
 in the etching step, the pressure in the chamber is not higher than 4 Pa.    
   
   
       32 . A plasma etching method according to  claim 1 , wherein 
 in the etching step, the pressure in the chamber is not higher than 1.33 Pa.    
   
   
       33 . A plasma etching unit according to  claim 18 , wherein 
 the pressure in the chamber is not higher than 4 Pa.    
   
   
       34 . A plasma etching unit according to  claim 18 , wherein 
 the pressure in the chamber is not higher than 1.33 Pa.