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 is connected to the upper electrode. 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 while any one of application voltage, application current, and application power from the variable DC power supply to the upper electrode is controlled, to generate plasma of the process gas so as to perform plasma etching.

1 . A plasma processing apparatus comprising:
 a process container that forms a process space to accommodate a target substrate;   an exhaust unit connected to an exhaust port of the process container to vacuum-exhaust gas from inside the process container;   an exhaust plate interposed between the process space and the exhaust port to rectify a flow of exhaust gas;   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 support the target substrate through a mount face;   a first RF power application unit configured to apply a first RF power to the first 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;   a process gas supply unit configured to supply a process gas into the process container; and   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, the conductive member being disposed as a ring around the first electrode,   wherein the first electrode includes outer and inner upper electrodes, which are electrically insulated from each other, disposed on a peripheral side and a central side, respectively, in a radial direction, and connected to the first RF power application unit, to define outer and inner RF discharge regions, respectively, and   the DC power supply is connected to at least the inner upper electrode.   
     
     
         2 . The plasma processing apparatus according to  claim 1 , wherein the DC power supply is connected to both of the outer and inner upper electrodes. 
     
     
         3 . The plasma processing apparatus according to  claim 2 , wherein the DC power supply includes a common DC power supply connected to the outer and inner upper electrodes and having a positive terminal grounded and a negative terminal connected to the outer and inner upper electrodes. 
     
     
         4 . The plasma processing apparatus according to  claim 2 , wherein the DC power supply includes first and second DC power supplies respectively connected to the outer and inner upper electrodes and having positive terminals grounded and negative terminals respectively connected to the outer and inner upper electrodes. 
     
     
         5 . The plasma processing apparatus according to  claim 2 , wherein the DC power supply includes a common DC power supply connected to the outer and inner upper electrodes and having a positive terminal connected to the inner upper electrode and a negative terminal connected to the outer upper electrode. 
     
     
         6 . The plasma processing apparatus according to  claim 1 , wherein the first RF power application unit is connected to the outer and inner upper electrodes through a power supply mechanism configured to apply the first RF power to the outer and inner upper electrodes at a predetermined ratio therebetween. 
     
     
         7 . The plasma processing apparatus according to  claim 1 , wherein the DC power supply is connected to the first electrode through an on/off switch and a filter configured to trap radio frequencies derived from the first and second RF powers. 
     
     
         8 . The plasma processing apparatus according to  claim 1 , wherein the inner upper electrode includes outer and inner gas passages formed therein, which are isolated from each other, disposed on a peripheral side and a central side, respectively, in a radial direction, and connected to the process gas supply unit, to define outer and inner gas delivery regions, respectively. 
     
     
         9 . The plasma processing apparatus according to  claim 8 , wherein the process gas supply unit is connected to the outer and inner gas passages through a gas supply mechanism configured to supply the process gas to the outer and inner gas passages with conditions different therebetween in a parameter selected from the group consisting of flow rate, gas type, and gas mixture ratio. 
     
     
         10 . The plasma processing apparatus according to  claim 1 , further comprising a switching mechanism configured to switch from a first state where the conductive member is connected to a ground potential portion to a second state where the conductive member is connected to a negative potential portion or set in floating. 
     
     
         11 . The plasma processing apparatus according to  claim 10 , wherein the switching mechanism forms the first state such that a negative terminal of the DC power supply is connected to the first electrode and a positive terminal of the DC power supply is grounded. 
     
     
         12 . The plasma processing apparatus according to  claim 11 , wherein the switching mechanism forms the second state such that the negative terminal of the DC power supply is connected to the conductive member. 
     
     
         13 . The plasma processing apparatus according to  claim 12 , wherein the switching mechanism forms the second state such that the positive terminal of the DC power supply is connected to the first electrode. 
     
     
         14 . The plasma processing apparatus according to  claim 1 , wherein the conductive member is disposed to be heated by the first electrode supplied with the first RF power. 
     
     
         15 . The plasma processing apparatus according to  claim 1 , further comprising a silicon-containing member that is other than the first electrode and is disposed adjacent to the conductive member. 
     
     
         16 . The plasma processing apparatus according to  claim 1 , wherein the conductive member has a recess to prevent flying substances from being deposited during a plasma process. 
     
     
         17 . The plasma processing apparatus according to  claim 1 , wherein a cover plate is disposed to partly cover the conductive member, and the cover plate is moved relative to the conductive member by a driving mechanism to change a portion of the conductive member to be exposed to plasma. 
     
     
         18 . The plasma processing apparatus according to  claim 1 , wherein a cover film having a stepped shape and made of a material to be etched by plasma is disposed to partly cover the conductive member, and the cover film is configured to be etched to change a portion of the conductive member to be exposed to plasma.