Plasma processing apparatus and method

Abstract

An apparatus includes an upper electrode and a lower electrode for supporting a wafer disposed opposite each other within a process chamber. A first RF power supply configured to apply a first RF power having a relatively higher frequency, and a second RF power supply configured to apply a second RF power having a relatively lower frequency is connected to the lower electrode. A variable DC power supply is connected to the upper electrode. A process gas is supplied into the process chamber to generate plasma of the process gas so as to perform plasma etching.

1 . A plasma processing apparatus comprising:
 a process container configured to accommodate a target substrate and to be vacuum-exhausted;   a first electrode and a second electrode disposed opposite each other within the process container, the first electrode being an upper electrode and the second electrode being a lower electrode and configured to place the target substrate thereon;   a first RF power application unit configured to apply a first RF power to the second electrode;   a second RF power application unit configured to apply a second RF power to the second electrode, the second RF power having a frequency lower than that of the first RF power;   a DC power supply configured to apply a DC voltage to the first electrode; and   a process gas supply unit configured to supply a process gas into the process container,   wherein the first electrode is in a floating state relative to ground potential in a sense of DC.   
     
     
         2 . The plasma processing apparatus according to  claim 1 , wherein the plasma processing apparatus further comprises a switching mechanism configured to switch the first electrode between the floating state and a grounded state where the first electrode is connected to ground potential in a sense of DC. 
     
     
         3 . The plasma processing apparatus according to  claim 2 , wherein the switching mechanism sets the first electrode in the floating state when the DC voltage is applied to the first electrode, and sets the first electrode in the floating state or the grounded state when the DC voltage is not applied to the first electrode. 
     
     
         4 . The plasma processing apparatus according to  claim 2 , wherein the plasma processing apparatus further comprises a control section configured to control an operation of the plasma processing apparatus and including a computer and a non-transitory storage medium storing a control program for execution on the computer, and the control program, when executed, causes the computer to control the plasma processing apparatus to selectively set a first plasma etching mode where the first electrode is in the floating state while the DC voltage is applied to the first electrode, and a second plasma etching mode where the first electrode is in the floating state or the grounded state while the DC voltage is not applied to the first electrode. 
     
     
         5 . The plasma processing apparatus according to  claim 1 , wherein the DC power supply is configured such that any one of application voltage, application current, and application power to the first electrode is variable. 
     
     
         6 . The plasma processing apparatus according to  claim 1 , wherein the plasma processing apparatus further comprises a control unit configured to control any one of application voltage, application current, and application power from the DC power supply to the first electrode. 
     
     
         7 . The plasma processing apparatus according to  claim 6 , wherein the control unit is configured to control whether the DC voltage to be applied or not, from the DC power supply to the first electrode. 
     
     
         8 . The plasma processing apparatus according to  claim 6 , wherein the plasma processing apparatus further comprises a detector configured to detect a generated plasma state, and the control unit controls any one of the application voltage, application current, and application power from the DC power supply to the first electrode, based on information from the detector. 
     
     
         9 . The plasma processing apparatus according to  claim 1 , wherein the first RF power has a frequency of 27 MHz or more. 
     
     
         10 . The plasma processing apparatus according to  claim 9 , wherein the first RF power has a frequency of 40 MHz or more. 
     
     
         11 . The plasma processing apparatus according to  claim 1 , wherein the second RF power has a frequency of 13.56 MHz or less. 
     
     
         12 . The plasma processing apparatus according to  claim 1 , wherein the DC voltage is a voltage of −2,000 to +1,000V. 
     
     
         13 . The plasma processing apparatus according to  claim 1 , wherein a surface of the first electrode facing the second electrode is made of a silicon-containing substance. 
     
     
         14 . The plasma processing apparatus according to  claim 1 , wherein the plasma processing apparatus further comprises a conductive member disposed within the process container and grounded to release through plasma a current caused by the DC voltage applied from the DC power supply to the first electrode. 
     
     
         15 . The plasma processing apparatus according to  claim 14 , wherein the conductive member is disposed around the second electrode. 
     
     
         16 . The plasma processing apparatus according to  claim 14 , wherein the conductive member is disposed near the first electrode. 
     
     
         17 . The plasma processing apparatus according to  claim 16 , wherein the conductive member is disposed to form a ring shape around the first electrode. 
     
     
         18 . The plasma processing apparatus according to  claim 14 , wherein the conductive member has a recess to prevent flying substances from being deposited during a plasma process.