Plasma processing apparatus and heater temperature control method

Abstract

A plasma processing apparatus is provided that converts a gas into plasma using a high frequency power and performs a plasma process on a workpiece using an action of the plasma. The plasma processing apparatus includes a processing chamber that can be depressurized, a mounting table that is arranged within the processing chamber and holds the workpiece, an electrostatic chuck that is arranged on the mounting table and electrostatically attracts the workpiece by applying a voltage to a chuck electrode, a heater arranged within or near the electrostatic chuck, and a temperature control unit. The heater is divided into a circular center zone, at least two middle zones arranged concentrically at an outer periphery side of the center zone, and an edge zone arranged concentrically at an outermost periphery. The temperature control unit adjusts a control temperature of the heater with respect to each of the zones.

1 . A plasma processing apparatus configured to convert a gas into plasma using a high frequency power and perform a plasma process on a workpiece using an action of the plasma, the plasma processing apparatus comprising:
 a processing chamber that can be depressurized;   a mounting table that is arranged within the processing chamber and is configured to hold the workpiece;   an electrostatic chuck that is arranged on the mounting table and is configured to electrostatically attract the workpiece by applying a voltage to a chuck electrode;   a heater arranged within or near the electrostatic chuck, the heater being divided into a plurality of zones including a circular center zone, at least two middle zones arranged concentrically at an outer periphery side of the center zone, and an edge zone arranged concentrically at an outermost periphery; and   a temperature control unit configured to adjust a control temperature of the heater with respect to each of the plurality of zones.   
     
     
         2 . The plasma processing apparatus as claimed in  claim 1 , wherein the heater is arranged such that the center zone and the at least two middle zones have areas that become smaller toward the outer periphery side, and an outermost middle zone of the at least two middle zones has an area that is smaller than an area of the edge zone arranged at the outer periphery side of the outermost middle zone. 
     
     
         3 . The plasma processing apparatus as claimed in  claim 1 , wherein the heater is arranged such that the center zone, the at least two middle zones, and the edge zone have areas that become smaller toward the outer periphery side. 
     
     
         4 . The plasma processing apparatus as claimed in  claim 2 , wherein the temperature control unit turns off the heater of the outermost middle zone and adjusts the control temperature of the heater of the zones other than the outermost middle zone. 
     
     
         5 . The plasma processing apparatus as claimed in  claim 1 , wherein the temperature control unit corrects a deviation of a surface temperature of the electrostatic chuck with respect to a setting temperature of each of the zones upon adjusting the control temperature of the heater with respect to each of the zones. 
     
     
         6 . The plasma processing apparatus as claimed in  claim 1 , wherein the temperature control unit corrects a temperature interference from an adjacent zone with respect to a setting temperature of each of the zones upon adjusting the control temperature of the heater with respect to each of the zones. 
     
     
         7 . The plasma processing apparatus as claimed in  claim 6 , further comprising:
 a temperature setting unit configured to set up a first correction value for correcting a deviation of a surface temperature of the electrostatic chuck with respect to the setting temperature of each of the zones and a second correction value for correcting the temperature interference from the adjacent zone with respect to the setting temperature of each of the zones;   wherein the temperature control unit adjusts the control temperature of the heater with respect to each of the zones based on the first correction value and the second correction value.   
     
     
         8 . The plasma processing apparatus as claimed in  claim 7 , wherein
 the temperature setting unit stores in advance in a storage unit a correlation between the setting temperature of each of the zones and a current value to be applied to the heater of each of the zones to control the heater to the control temperature that is calculated with respect to each of the zones based on the first correction value and the second correction value; and   the temperature control unit acquires a temperature detected by a temperature sensor arranged in at least one zone of the plurality of zones, sets up the acquired temperature as a setting temperature of the at least one zone, and calculates the current value to be applied to the heater of each of the zones based on the setting temperature of the at least one zone and the correlation stored in the storage unit.   
     
     
         9 . The plasma processing apparatus as claimed in  claim 8 , further comprising:
 a determination unit configured to determine that a time for replacement of the electrostatic chuck has been reached when at least one current value of the calculated current value for the heater of each of the zones is less than a predetermined threshold value.   
     
     
         10 . The plasma processing apparatus as claimed in  claim 8 , wherein at least three temperature sensors are arranged along a circumference of a circle within the at least one zone. 
     
     
         11 . The plasma processing apparatus as claimed in  claim 1 , further comprising:
 a coolant path arranged opposite the heater, which is arranged within or near the mounting table; and   a chiller device configured to circulate a coolant within the coolant path.   
     
     
         12 . The plasma processing apparatus as claimed in  claim 1 , wherein
 the mounting table holds the workpiece that has a diameter greater than or equal to 450 mm; and   the middle zones of the heater are concentrically divided into at least three zones.   
     
     
         13 . A heater temperature control method for controlling a temperature of a heater arranged in a plasma processing apparatus, which is configured to convert a gas into plasma using a high frequency power and perform a plasma process on a workpiece using an action of the plasma, wherein
 the plasma processing apparatus includes
 a processing chamber that can be depressurized; 
 a mounting table that is arranged within the processing chamber and is configured to hold the workpiece; 
 an electrostatic chuck that is arranged on the mounting table and is configured to electrostatically attract the workpiece by applying a voltage to a chuck electrode; 
 a heater arranged within or near the electrostatic chuck, the heater being divided into a plurality of zones including a circular center zone, at least two middle zones arranged concentrically at an outer periphery side of the center zone, and an edge zone arranged concentrically at an outermost periphery; and 
 a storage unit that stores in advance a correlation between a setting temperature of each of the zones and a current value to be applied to the heater to control the heater to a control temperature of each of the zones, the control temperature being obtained by correcting a deviation of a surface temperature of the electrostatic chuck with respect to the setting temperature of each of the zones and correcting a temperature interference from an adjacent zone with respect to the setting temperature of each of the zones; 
   the heater temperature control method comprising the steps of:
 acquiring a temperature detected by a temperature sensor arranged in at least one zone of the plurality of zones and setting up the acquired temperature as a setting temperature of the at least one zone; 
 calculating a current value to be applied to the heater of each of the zones based on the acquired setting temperature of the at least one zone and the correlation stored in the storage unit; and 
 controlling the temperature of the heater of each of the zones by applying the calculated current value to the heater of each of the zones.