Plasma etching apparatus and plasma cleaning method

Abstract

A plasma etching apparatus includes an electrostatic chuck and an etching gas supply unit for supplying an etching gas to a processing space between a first and a second electrode to perform a dry etching process on the target object. The apparatus further includes a cleaning gas supply unit for supplying a cleaning gas to a processing space; a first high frequency power supply unit for supplying a first high frequency power to the first electrode; and a controller for controlling the first high frequency power supply unit such that a first period during which the first high frequency power has a first amplitude that generates the plasma and a second period during which the first high frequency power has a second amplitude that generates substantially no plasma are alternately repeated at a specific cycle when the plasma cleaning is performed in the processing chamber without the target object.

1 . A plasma etching apparatus comprising:
 an evacuable processing chamber;   a first electrode for mounting a target object in the processing chamber;   an electrostatic chuck provided on a mounting surface of the first electrode to hold the target object by an electrostatic force, a dielectric material of a surface layer portion of the electrostatic chuck including a metal;   a second electrode disposed to face the first electrode in parallel in the processing chamber;   an etching gas supply unit for supplying an etching gas to a processing space between the first and the second electrode to perform a dry etching process on the target object;   a cleaning gas supply unit for supplying a cleaning gas to the processing space to perform a plasma cleaning in the processing chamber without the target object;   a first high frequency power supply unit for supplying a first high frequency power to the first electrode, the first high frequency power contributing to plasma generation of the etching gas or the cleaning gas; and   a controller for controlling the first high frequency power supply unit such that a first period during which the first high frequency power has a first amplitude that generates the plasma and a second period during which the first high frequency power has a second amplitude that generates substantially no plasma are alternately repeated at a specific cycle when the plasma cleaning is performed in the processing chamber without the target object.   
   
   
       2 . The apparatus of  claim 1 , wherein the dielectric material of the surface layer portion of the electrostatic chuck includes Al 2 O 3 . 
   
   
       3 . The apparatus of  claim 1 , wherein the second amplitude is zero. 
   
   
       4 . The apparatus of  claim 1 , wherein a frequency at which the first and the second period are alternately repeated is about 1 kHz to 60 kHz. 
   
   
       5 . The apparatus of  claim 1 , wherein a duty of the first period is about 10% to 60%. 
   
   
       6 . The apparatus of  claim 1 , wherein, during the plasma cleaning, the controller controls the first high frequency power supply unit such that the first high frequency power continuously has the first amplitude between a point of time when the first high frequency power is started to be supplied to the first electrode and a point of time when the plasma is ignited; and the first period and the second period are alternately repeated at the specific cycle after the point of time when the plasma is ignited. 
   
   
       7 . The apparatus of  claim 1 , wherein, during the plasma cleaning, the controller controls the first high frequency power supply unit such that the first high frequency power continuously has the first amplitude until a discharge of the cleaning gas becomes stable; and the first period and the second period are alternately repeated at the specific cycle after the discharge of the cleaning gas becomes stable. 
   
   
       8 . The apparatus of  claim 1 , wherein a plasma cleaning time set for the plasma cleaning is divided into a first and a second cleaning time; and the controller controls the first high frequency power supply unit such that the first high frequency power continuously has the first amplitude during the first cleaning time and the first period and the second period are alternately repeated at the specific cycle during the second cleaning time. 
   
   
       9 . The apparatus of  claim 1 , wherein the controller controls the first high frequency power supply unit such that the first period and the second period are alternately repeated at the specific cycle between a start and an end point of a plasma cleaning time set for the plasma cleaning. 
   
   
       10 . The apparatus of  claim 1 , wherein the cleaning gas is a gaseous mixture in which SF 6  gas or NF 3  gas and O 2  gas are mixed. 
   
   
       11 . The apparatus of  claim 10 , wherein a mixing ratio of the O 2  gas to the SF 6  gas or the NF 3  gas is about 1. 
   
   
       12 . The apparatus of  claim 1 , wherein the plasma cleaning is regularly performed in lot by lot or sheet by sheet. 
   
   
       13 . The apparatus of  claim 1 , further comprising: a second high frequency power supply unit for supplying to the first electrode a second high frequency power for controlling an energy of ions attracted to the target object from the plasma of the etching gas during the dry etching process. 
   
   
       14 . The apparatus of  claim 13 , wherein, when the plasma cleaning is performed in the processing chamber without the target object, the controller controls the second high frequency power supply unit not to supply the second high frequency power to the first electrode. 
   
   
       15 . A plasma cleaning method for performing a plasma cleaning in an evacuable processing chamber without a target object in a plasma etching apparatus including:
 the evacuable processing chamber;   a first electrode for mounting a target object in the processing chamber;   an electrostatic chuck provided on a mounting surface of the first electrode to hold the target object by an electrostatic force, a dielectric material of a surface layer portion of the electrostatic chuck including a metal;   a second electrode disposed to face the first electrode in parallel in the processing chamber;   an etching gas supply unit configured to supply an etching gas to a processing space between the first and the second electrode to perform a dry etching process on the target object;   a cleaning gas supply unit for supplying a cleaning gas to the processing space to perform a plasma cleaning in the processing chamber without the target object; and   a first high frequency power supply unit for supplying a first high frequency power to the first electrode, the first high frequency power contributing to plasma generation of the etching gas or the cleaning gas,   wherein a first period during which the first high frequency power has a first amplitude that generates the plasma and a second period during which the first high frequency power has a second amplitude that generates substantially no plasma are alternately repeated at a specific cycle.   
   
   
       16 . The method of  claim 15 , wherein the dielectric material of the surface layer portion of the electrostatic chuck includes Al 2 O 3 . 
   
   
       17 . The method of  claim 15 , wherein the second amplitude is zero. 
   
   
       18 . The method of  claim 15 , wherein a frequency at which the first and the second period are alternately repeated is about 1 kHz to 60 kHz. 
   
   
       19 . The method of  claim 15 , wherein a duty of the first period is about 10% to 60%. 
   
   
       20 . The method of  claim 15 , wherein, during the plasma cleaning, the first high frequency power supply unit is controlled such that the first high frequency power continuously has the first amplitude between a point of time when the first high frequency power is started to be supplied to the first electrode and a point of time when the plasma is ignited; and the first period and the second period are alternately repeated at the specific cycle after the point of time when the plasma is ignited. 
   
   
       21 . The method of  claim 15 , wherein, during the plasma cleaning, the first high frequency power supply unit is controlled such that the first high frequency power continuously has the first amplitude until a discharge of the cleaning gas becomes stable; and the first period and the second period are alternately repeated at the specific cycle after the discharge of the cleaning gas becomes stable. 
   
   
       22 . The method of  claim 15 , wherein, wherein a plasma cleaning time set for the plasma cleaning is divided into a first and a second cleaning time; and the first high frequency power supply unit is controlled such that the first high frequency power continuously has the first amplitude during the first cleaning time and the first period and the second period are alternately repeated at the specific cycle during the second cleaning time. 
   
   
       23 . The method of  claim 15 , wherein the first high frequency power supply unit is controlled such that the first period and the second period are alternately repeated at the specific cycle between a start and an end point of a plasma cleaning time set for the plasma cleaning. 
   
   
       24 . The method of  claim 15 , wherein the cleaning gas is a gaseous mixture in which SF 6  gas or NF 3  gas and O 2  gas are mixed. 
   
   
       25 . The method of  claim 24 , wherein a mixing ratio of the O 2  gas to the SF 6  gas or the NF 3  gas is about 1. 
   
   
       26 . The method of  claim 15 , wherein the plasma cleaning is regularly performed lot by lot or sheet by sheet.