Patent Publication Number: US-2012024819-A1

Title: Plasma processing apparatus and plasma processing method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2010-171917, filed on Jul. 30, 2010; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a plasma processing apparatus and a plasma processing method. 
     BACKGROUND 
     In manufacture of electronic devices such as semiconductor devices, for example, processing using plasma such as dry etching and CVD (Chemical Vapor Deposition) is performed. 
     In order to obtain high-density plasma, for example, if a frequency of excitation power is increased, plasma density at the center of a processing chamber becomes extremely higher than at the peripheral part, and in-plane distribution of the plasma density becomes large. 
     In order to uniformly process a substrate to be processed, plasma density uniform in a plane is desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view illustrating the configuration of a plasma processing apparatus according to a first embodiment; 
         FIGS. 2A to 2L  are schematic views illustrating operations of the plasma processing apparatus according to the first embodiment; 
         FIG. 3  is a schematic view illustrating characteristics of a dielectric member used in the plasma processing apparatus according to the first embodiment; 
         FIG. 4  is a schematic view illustrating another characteristic of the dielectric member used in the plasma processing apparatus according to the first embodiment; 
         FIGS. 5A to 5C  are schematic cross-sectional views illustrating the configuration of another plasma processing apparatus according to the first embodiment; 
         FIGS. 6A to 6D  are schematic views illustrating another operation of the plasma processing apparatus according to the first embodiment; 
         FIG. 7  is a schematic cross-sectional view illustrating the configuration of another plasma processing apparatus according to the first embodiment; 
         FIGS. 8A to 8F  are schematic views illustrating operations of another plasma processing apparatus according to the first embodiment; 
         FIG. 9  is a schematic cross-sectional view illustrating the configuration of another plasma processing apparatus according to the first embodiment; 
         FIG. 10  is a flowchart illustrating a plasma processing method according to a second embodiment; 
         FIG. 11  is a flowchart illustrating another plasma processing method according to the second embodiment; and 
         FIGS. 12A and 12B  are schematic views illustrating operations of another plasma processing method according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a plasma processing apparatus includes a first electrode, a second electrode, a dielectric member, and a control unit. Plasma is generated between the first electrode and the second electrode. The dielectric member is provided between the first electrode and the second electrode. The control unit is configured to change relative dielectric constant of the dielectric member in a plane crossing a first direction from the first electrode to the second electrode. 
     Embodiments will now be described with reference to the drawings. 
     The drawings are schematic or conceptual; and the relationships between the thickness and width of portions, the proportional coefficients of sizes among portions, etc., are not necessarily the same as the actual values thereof. Further, the dimensions and proportional coefficients may be illustrated differently among drawings, even for identical portions. 
     In the specification of the application and the drawings, components similar to those described in regard to a drawing thereinabove are marked with like reference numerals, and a detailed description is omitted as appropriate. 
     First Embodiment 
     A plasma processing apparatus according to the embodiment can be applied to any processing apparatus using plasma such as a dry etching apparatus using plasma, a film forming apparatus using plasma including a plasma CVD apparatus and the like. An example in which the plasma processing apparatus according to the embodiment will be described below. The example is applied to a dry etching apparatus using plasma. Among the dry etching apparatuses, a capacitively coupled plasma (CCP) processing apparatus will be described as an example. 
       FIG. 1  is a schematic cross-sectional view illustrating the configuration of a plasma processing apparatus according to a first embodiment. 
       FIGS. 2A to 2L  are schematic views illustrating operations of the plasma processing apparatus according to the first embodiment. 
     As illustrated in  FIG. 1 , the plasma processing apparatus  110  according to the embodiment is provided with a processing chamber  5 , a first electrode  10 , a second electrode  20 , a dielectric member  30 , and a control unit  40  (a relative dielectric constant control unit). 
     The processing chamber  5  is a chamber whose inside can be sealed, for example, and a wafer  60  (an object to be processed by plasma) can be contained inside. 
     The first electrode  10  and the second electrode  20  are provided inside the processing chamber  5 . In the specific example, the first electrode  10  and the second electrode  20  are parallel plates. 
     The first electrode  10  is provided in the lower side in the processing chamber  5 , for example. The second electrode  20  is opposed to the first electrode  10 , for example. In the specific example, the second electrode  20  is disposed in the upper side in the processing chamber  5 . However, arrangement of the first electrode  10  and the second electrode  20  in the processing chamber  5  is arbitrary. 
     In the specific example, the first electrode  10  is provided inside an ESC (Electro Static Chuck)  15 . The ESC  15  has a wafer holding section  11  made of ceramic, for example, and the first electrode  10  is buried inside the wafer holding section  11 . The ESC  15  absorbs the wafer  60  by an electrostatic force and holds the wafer  60 . 
     A high-frequency power source  70  is connected to a circuit including the first electrode  10  and the second electrode  20 . In the specific example, the high-frequency power source  70  is connected to the first electrode  10 , and the second electrode  20  is grounded. By high-frequency power supplied from the high-frequency power source  70 , plasma is generated in a space  50  between the first electrode  10  and the second electrode  20 . The plasma processing apparatus  110  may include the high-frequency power source  70 , or the high-frequency power source  70  may be provided separately from the plasma processing apparatus  110 . 
     As described above, plasma is generated between the first electrode  10  and the second electrode  20 . 
     The dielectric member  30  is provided between the first electrode  10  and the second electrode  20 . 
     In the specific example, as described above, the second electrode  20  is provided above the first electrode  10 , and the wafer  60  (an object to be processed) is disposed between the first electrode  10  and the dielectric member  30  so that plasma processing can be performed. That is, the dielectric member  30  is disposed above the position where the wafer  60  is disposed (on the side of the second electrode  20 ). 
     The control unit  40  changes relative dielectric constant of the dielectric member  30  in a plane crossing a first direction from the first electrode  10  to the second electrode  20 . The control unit  40  forms in-plane distribution of the relative dielectric constant in the dielectric member  30  without changing the material of the dielectric member  30  by controlling at least one of a thermal state of the dielectric member  30  and an external force including a mechanical force applied by the dielectric member  30 . As a result, the in-plane distribution of the relative dielectric constant of the dielectric member  30  can be easily controlled, and the in-plane distribution can be changed easily. 
     Here, the first direction from the first electrode  10  to the second electrode  20  is taken as a Z-axis direction. One direction perpendicular to the Z-axis direction is taken as an X-axis direction (second direction). A direction perpendicular to the Z-axis direction and the X-axis direction is taken as a Y-axis direction (third direction). An X-Y plane is a plane perpendicular to the Z-axis direction. 
     A plane crossing the Z-axis direction from the first electrode  10  to the second electrode  20  is the X-Y plane, for example. The dielectric member  30  is a structural body in a plate shape, a sheet shape, a layer shape or a film shape having a surface parallel with the X-Y plane, for example. The dielectric member  30  does not necessarily have to be planar but may be linear extending along the X-Y plane, for example (a folded linear shape, for example). In the following, explanation will be made assuming that the dielectric member  30  has a plane shape, for example (or a sheet shape, a layer shape or a film shape). 
     The control unit  40  changes the relative dielectric constant of the dielectric member  30  in the X-Y plane crossing the Z-axis direction, that is, in the plane of the dielectric member  30 . The control unit  40  can make the relative dielectric constant of the dielectric member  30  non-uniform in the plane and form in-plane distribution of the relative dielectric constant. 
     For example, in a plasma processing apparatus of a reference example in which the dielectric member  30  and the control unit  40  are not provided, the plasma density at the center part of the processing chamber  5  tends to become high, while the plasma density at the peripheral part tends to become low. That is, the in-plane distribution of the plasma density is large, and the plasma density is not uniform. 
     On the other hand, in the plasma processing apparatus  110  according to the embodiment, in order to compensate for the distribution of the plasma density formed in the plasma processing apparatus of the reference example, the relative dielectric constant of the dielectric member  30  is made uneven in the plane, and the in-plane distribution of the relative dielectric constant is formed. As a result, non-uniformity of the plasma density in the plane is reduced. 
     The relative dielectric constant of the dielectric member  30  is changed in accordance with the temperature, for example. At this time, the control unit  40  changes the temperature of the dielectric member  30  in the plane of the dielectric member  30  and forms the in-plane distribution of the temperature. As a result, the in-plane distribution of the relative dielectric constant of the dielectric member  30  is formed. For the control unit  40 , a heater such as a resistance wire heater and an infrared heater (including a lamp) or a cooler can be used. 
     As illustrated in  FIG. 1 , a driving section  42  is connected to the control unit  40 , for example. The driving section  42  controls the control unit  40 . The driving section  42  includes an electronic circuit and the like and supplies an electric current for control including an electric signal to the control unit  40 . The driving section  42  may be considered as a part of the control unit  40 . The plasma processing apparatus  110  may include the driving section  42 , and the driving section  42  may be provided separately from the plasma processing apparatus  110 . 
     The relative dielectric constant of the dielectric member  30  can be two cases, that is, one case having positive temperature dependency and the other case having negative temperature dependency. The temperature dependency depends on the type of the material used as the dielectric member  30 , a temperature range and the like. 
     First, the case in which the relative dielectric constant of the dielectric member  30  has positive temperature dependency will be described below. 
       FIG. 2A  is a graph schematically illustrating the temperature characteristic of the dielectric member  30 . That is, the horizontal axis in the figure indicates a temperature Td of the dielectric member  30 , and the vertical axis indicates relative dielectric constant ε r  of the dielectric member  30 . 
       FIGS. 2B and 2C  schematically illustrate a control operation of the control unit  40 . The horizontal axes in these figures indicate positions along the X-axis direction. A position Xc corresponds to the position at the center of the processing chamber  5 , for example, a position X 1  corresponds to a position at one end of a processing region of the processing chamber  5 , and a position X 2  corresponds to a position of the other end. The vertical axis in  FIG. 2B  indicates the temperature Td of the dielectric member  30  controlled by the control unit  40 . The vertical axis in  FIG. 2C  is the relative dielectric constant ε r  of the dielectric member  30 . 
       FIGS. 2D to 2F  schematically illustrate states of the plasma processing apparatus  110  obtained by the control operation of the control unit  40 . The horizontal axes in these figures indicate positions in the X-axis direction. The vertical axis in  FIG. 2D  indicates capacitance C between the first electrode  10  and the second electrode  20 . The vertical axis in  FIG. 2E  indicates impedance Cz between the first electrode  10  and the second electrode  20 . The vertical axis in  FIG. 2F  indicates plasma density Cp generated between the first electrode  10  and the second electrode  20 . In  FIG. 2F , in addition to the characteristics in the plasma processing apparatus  110  according to the embodiment illustrated by a solid line, the characteristics of a plasma processing apparatus  119  as the above reference example are also illustrated by a broken line. 
     As illustrated in  FIG. 2A , the relative dielectric constant ε r  of the dielectric member  30  is low when the temperature Td is low and high when the temperature Td is high. That is, the relative dielectric constant ε r  has positive temperature dependency  110   a.    
     At this time, as illustrated in  FIG. 2B , the temperature Td of the dielectric member  30  is controlled higher at the outer positions X 1  and X 2  than at the center position Xc by the control unit  40 . 
     As a result, as illustrated in  FIG. 2C , the relative dielectric constant ε r  of the dielectric member  30  becomes higher at the outer positions X 1  and X 2  than the center position Xc. 
     That is, the control unit  40  makes the relative dielectric constant of outer portions of the dielectric member  30  higher than the relative dielectric constant of a portion at the center in the X-Y plane (a plane orthogonal to the Z-axis direction) in the dielectric member  30 . The outer portions are located on the outer sides from the center portion in the X-Y plane in the dielectric member  30 . 
     The capacitance C between the first electrode  10  and the second electrode  20  is expressed as C=ε 0 ·ε r ·S/d. Here, ε 0  denotes dielectric constant of vacuum, S denotes an area of a portion where the first electrode  10  and the second electrode  20  oppose each other, and d denotes a distance between the first electrode  10  and the second electrode  20 . 
     Therefore, as illustrated in  FIG. 2D , the capacitance C between the first electrode  10  and the second electrode  20  becomes larger at the outer positions X 1  and X 2  than at the center position Xc. 
     Impedance Cz between the first electrode  10  and the second electrode  20  is expressed as |Cz|=1/(ωC). Here, ω is an angular frequency of high-frequency power supplied by the high-frequency power source  70  (ω=2πf when a frequency is f). 
     Therefore, as illustrated in  FIG. 2E , the impedance Cz between the first electrode  10  and the second electrode  20  becomes smaller at the outer positions X 1  and X 2  than at the center position Xc. 
     If the impedance Cz is small, an ion current is increased, and plasma density Cp is increased. As a result, as illustrated by a solid line in  FIG. 2F , the plasma density Cp is made uniform at the center position Xc and at the outer positions X 1  and X 2 . 
     That is, as indicated by a broken line in  FIG. 2F , in the plasma processing apparatus  119  of the reference example in which the dielectric member  30  and the control unit  40  are not provided, the plasma density Cp is extremely higher at the center position Xc than at the outer positions X 1  and X 2 . 
     On the other hand, in the plasma processing apparatus  110  according to the embodiment, by setting the relative dielectric constant ε r  of the dielectric member  30  higher on the outside than at the center portion, the in-plane distribution of the plasma density Cp is compensated, and non-uniformity of the plasma density Cp can be reduced. As a result, according to the embodiment, a plasma processing apparatus having excellent controllability of the plasma density Cp can be provided. 
     In the above, the characteristics along the X-axis direction have been described, but the same applies to the characteristics along the Y-axis direction. That is, according to the embodiment, the characteristics of the plasma density Cp in the X-Y plane can be controlled. 
     By using the plasma processing apparatus  110  according to the embodiment, non-uniformity of the plasma density Cp in the plane can be reduced, and thus, a silicon oxide film of the wafer  60  can be uniformly etched in the plane, for example. 
     Subsequently, a case in which the relative dielectric constant ε r  of the dielectric member  30  has negative temperature dependency will be described. 
       FIG. 2G  is a graph schematically illustrating the temperature characteristics of the dielectric member  30 .  FIGS. 2H and 2I  schematically illustrate the control operation of the control unit  40 .  FIGS. 2J to 2L  schematically illustrate states of the plasma processing apparatus  110  obtained by the control operation of the control unit  40 . 
     As illustrated in  FIG. 2G , the relative dielectric constant ε r  of the dielectric member  30  is high when the temperature Td is low and low when the temperature Td is high. That is, the relative dielectric constant ε r  has negative temperature dependency  110   b.    
     At this time, as illustrated in  FIG. 2H , the temperature Td of the dielectric member  30  is controlled lower at the outer positions X 1  and X 2  than at the center position Xc by the control unit  40 . 
     As a result, as illustrated in  FIG. 2I , the relative dielectric constant ε r  of the dielectric member  30  becomes higher at the outer positions X 1  and X 2  than at the center position Xc. As a result, as illustrated in  FIG. 2J , the capacitance C between the first electrode  10  and the second electrode  20  becomes larger at the outer positions X 1  and X 2  than at the center position Xc. And as illustrated in  FIG. 2K , the impedance Cz between the first electrode  10  and the second electrode  20  becomes smaller at the outer positions X 1  and X 2  than at the center position Xc. As a result, as illustrated by a solid line in  FIG. 2L , the plasma density Cp is made uniform at the center position Xc and at the positions X 1  and X 2 . 
     Then, the characteristics similar to those along the X-axis direction described above can be also obtained in the X-Y plane. 
     As described above, even if the relative dielectric constant ε r  has the negative temperature dependency  110   b,  the in-plane distribution of the plasma density Cp is compensated, and non-uniformity of the plasma density Cp can be reduced by the plasma processing apparatus  110  according to the embodiment. 
     The in-plane distribution of the plasma density Cp can be measured by Langmuir probe or the like, for example. 
     For the dielectric member  30 , any material whose relative dielectric constant is changed by an external stimulation can be used. For the dielectric member  30 , a ferroelectric material such as barium titanate (TiBaO 3 ), lead zirconate (PbZrO 3 ), calcium titanate (CaTiO 3 ), strontium titanate (SrTiO 3 ), tri-glycine sulfate (TGS) and the like can be used. 
       FIG. 3  is a schematic view illustrating characteristics of a dielectric member used in the plasma processing apparatus according to the first embodiment. 
     That is,  FIG. 3  is a graph illustrating the characteristic of the dielectric member  30  when a ferroelectric material such as barium titanate is used for the dielectric member  30 . The horizontal axis indicates the temperature Td and the vertical axis indicates the relative dielectric constant ε r . 
     As illustrated in  FIG. 3 , the relative dielectric constant ε r  changes greatly between a temperature lower than a phase transition temperature Tc (Curie temperature, for example) and a temperature higher than that. In a temperature region R 1  lower than the phase transition temperature Tc (a temperature region corresponding to a ferroelectric phase), the relative dielectric constant ε r  has the positive temperature dependency. If the temperature is increased from a temperature lower than the phase transition temperature Tc to a temperature higher than that, the relative dielectric constant ε r  rapidly increases at the phase transition temperature Tc. In a temperature zone R 2  higher than the phase transition temperature Tc (a temperature region corresponding to a paraelectric phase), the relative dielectric constant ε r  has the negative temperature dependency. 
     In the embodiment, the temperature Td of the dielectric member  30  may be controlled in a range of the temperature region R 1  having the positive temperature dependency. In addition, the temperature Td of the dielectric member  30  may be controlled in a range of the temperature region R 2  having the negative temperature dependency. Moreover, the temperature Td of the dielectric member  30  may be controlled in a temperature region including the temperature region R 1  and the temperature region R 2 . 
     For the dielectric member  30 , an organic material such as a polyamide resin, for example, may be used. 
       FIG. 4  is a schematic view illustrating another characteristic of the dielectric member used in the plasma processing apparatus according to the first embodiment. 
     That is,  FIG. 4  is a graph illustrating the characteristic of the dielectric member  30  when a polyamide resin is used for the dielectric member  30 . 
     As illustrated in  FIG. 4 , in this case, the relative dielectric constant ε r  has positive temperature dependency. 
     As described above, for the dielectric member  30 , any material, whether it is inorganic or organic, including a ferroelectric material and a paraelectric material can be used. On the basis of the temperature dependency of the material, the control unit  40  changes the temperature of the dielectric member  30  in the plane of the dielectric member  30  and changes the relative dielectric constant ε r  of the dielectric member  30  in the plane of the dielectric member  30 . 
     In this embodiment, since the relative dielectric constant ε r  of the dielectric member  30  is changed in the plane by changing the temperature of the dielectric member  30  in the plane, which is easy, and controllability of the relative dielectric constant ε r  is high. 
       FIGS. 5A to 5C  are schematic cross-sectional views illustrating the configuration of another plasma processing apparatus according to the first embodiment. 
     As illustrated in  FIG. 5A , a plasma processing apparatus  111  is further provided with a cover member  32  provided between the dielectric member  30  and the first electrode  10 . The cover member  32  is provided between the dielectric member  30  and a position where the wafer  60  is installed. The cover member  32  is provided between the space  50  in which plasma is generated and the dielectric member  30 . The cover member  32  has stability against the generated plasma, for example. By providing the cover member  32 , damage on the dielectric member  30  by the plasma can be suppressed. 
     As illustrated in  FIG. 5B , a plasma processing apparatus  112  is further provided with a temperature control section  12  provided between the first electrode  10  and the dielectric member  30  and configured to control a temperature of the wafer  60  (an object to be processed). In the specific example, the temperature control section  12  is buried in the wafer holding section  11  of the ESC  15 . 
     For the temperature control section  12 , a heater, for example, is used. By the temperature control section  12 , the temperature of the wafer  60  is changed in the plane of the wafer  60 . The temperature at the center part of the wafer  60  is set low, for example, and the temperature is set to increase along a direction from the center part to the peripheral part. 
     The processing using the plasma applied to the wafer  60  (at least one of etching or film formation, for example) has temperature dependency. If the surface temperature of the wafer  60  is high, for example, the etching speed increases compared with the case of a low temperature. That is, reactivity on the surface of the wafer  60  depends on a temperature. By using this characteristic, uniformity in processing in the plane of the wafer  60  can be further improved. 
     That is, by using both the effect of control on the plasma density Cp by controlling the relative dielectric constant ε r  of the dielectric member  30  in the plane and control of reactivity in the plane of the wafer  60  by controlling the temperature of the wafer  60  in the plane, plasma processing with higher controllability can be realized. 
     As illustrated in  FIG. 5C , in a plasma processing apparatus  113 , the dielectric member  30  and the control unit  40  are provided between the first electrode  10  and the position where the wafer  60  (an object to be processed) is disposed. In the specific example, the dielectric member  30  and the control unit  40  are buried in the wafer holding section  11  of the ESC  15 . In this case as well, by controlling the relative dielectric constant ε r  of the dielectric member  30 , the plasma density Cp can be controlled, and non-uniformity of the plasma density Cp can be reduced. As described above, in this example, the second electrode  20  is provided above the first electrode  10 , the dielectric member  30  is provided on the first electrode  10 , and the wafer  60  is disposed between the dielectric member  30  and the second electrode  20  and then, the processing is performed. 
     As described above, the dielectric member  30  (and the control unit  40 ) can be disposed at any place between the first electrode  10  and the second electrode  20  where plasma is generated. 
       FIGS. 6A to 6D  are schematic views illustrating another operation of the plasma processing apparatus according to the first embodiment. 
       FIG. 6A  illustrates in-plane distribution  110   c  of the relative dielectric constant ε r  of the dielectric member  30  controlled by the control unit  40 , and  FIG. 6B  illustrates the plasma density Cp corresponding to the in-plane distribution  110   c.    FIG. 6C  illustrates another in-plane distribution  110   d  of the relative dielectric constant ε r  of the dielectric member  30  controlled by the control unit  40 , and  FIG. 6D  illustrates the plasma density Cp corresponding to the in-plane distribution  110   d.    
     As illustrated in  FIG. 6A , in the in-plane distribution  110   c,  the relative dielectric constant ε r  is set low in a wide range including the center position Xc as compared with the example illustrated in  FIG. 2C . And the relative dielectric constant ε r  is controlled so that the relative dielectric constant ε r  is increased rapidly in the vicinity of the outer positions X 1  and X 2 . 
     In this case, as illustrated in  FIG. 6B , the plasma density Cp is high in the vicinities of the center position Xc and the outer positions X 1  and X 2 . And it is low in regions between the position Xc and the positions X 1  and X 2 . 
     As illustrated in  FIG. 6C , in the in-plane distribution  110   d,  a change rate of the relative dielectric constant ε r  is high in the vicinities of the center position Xc and the outer positions X 1  and X 2 . And it is low in an intermediate portion between the position Xc and the position X 1  and an intermediate portion between the position Xc and the position X 2 . 
     In this case, as illustrated in  FIG. 6D , the plasma density Cp is relatively uniform in a region including the center position Xc and high in the vicinities of the outer positions X 1  and X 2 . 
     As described above, the plasma density Cp is not only controlled uniformly in the X-Y plane but also can be controlled to any characteristic as illustrated in  FIGS. 6B and 6D . If workability of the wafer  60  has distribution in the plane of the wafer  60 , for example, more desirable processing can be performed by controlling the plasma density Cp in the plane to a desired characteristic. 
       FIG. 7  is a schematic cross-sectional view illustrating the configuration of another plasma processing apparatus according to the first embodiment. 
     As illustrated in  FIG. 7 , in another plasma processing apparatus  120  according to the embodiment, the control unit  40  changes a pressure to be applied to the dielectric member  30  in a plane crossing the Z-axis direction (the X-Y plane, for example, and in the plane of the dielectric member  30 ). 
     For example, the control unit  40  has a plurality of pressure application portions divided in the X-Y plane. The pressure by the pressure application portions are applied to the dielectric member  30 . For the pressure application portion, a member that is deformed mechanically or a member that is deformed on the basis of volume expansion and contraction by a signal from the outside, for example, is used. That is, the control unit  40  includes the pressure application portions that can apply pressures different from each other in the plane of the dielectric member  30  to the dielectric member  30 . 
     For the dielectric member  30 , a piezoelectric body, for example, whose relative dielectric constant ε r  is changed by the pressure applied from the outside is used. On the basis of a relationship between a structure of the piezoelectric body (crystal orientation, for example) and a direction of the pressure to be applied, the relative dielectric constant ε r  might have positive pressure dependency or the relative dielectric constant ε r  might have negative pressure dependency. 
       FIGS. 8A to 8F  are schematic views illustrating operations of another plasma processing apparatus according to the first embodiment. 
       FIG. 8A  is a graph schematically illustrating the pressure dependency (positive dependency) of the relative dielectric constant ε r  of the dielectric member  30 .  FIGS. 8B and 8C  schematically illustrate the control operation of the control unit  40 . The vertical axis in  FIG. 8B  indicates a pressure Fd applied to the dielectric member  30  controlled by the control unit  40 . The vertical axis in  FIG. 8C  is the relative dielectric constant ε r  of the dielectric member  30 . 
     As illustrated in  FIG. 8A , the relative dielectric constant ε r  of the dielectric member  30  is low when the pressure Fd is low and high when the pressure Fd is high. That is, the relative dielectric constant ε r  has positive pressure dependency  120   a.    
     At this time, as illustrated in  FIG. 8B , the pressure Fd applied to the dielectric member  30  by the unit  40  is controlled so as to be larger at the outer positions X 1  and X 2  than at the center position Xc. 
     As a result, as illustrated in  FIG. 8C , the relative dielectric constant ε r  of the dielectric member  30  becomes higher at the outer positions X 1  and X 2  than at the center position Xc. 
     As a result, as already described, the capacitance C becomes larger at the outer positions X 1  and X 2  than at the center position Xc, and the impedance Cz becomes smaller at the outer positions x 1  and X 2  than at the center position Xc and as a result, the plasma density Cp is made uniform in the plane. 
       FIG. 8D  is a graph schematically illustrating pressure dependency (negative dependency) of the relative dielectric constant ε r  of the dielectric member  30 .  FIGS. 8E and 8F  schematically illustrate the control operation of the control unit  40 . 
     As illustrated in  FIG. 8D , the relative dielectric constant ε r  of the dielectric member  30  is high when the pressure Fd is low and low when the pressure Fd is high. That is, the relative dielectric constant ε r  has negative pressure dependency  120   b.    
     At this time, as illustrated in  FIG. 8E , the pressure Fd applied to the dielectric member  30  by the control unit  40  is controlled so as to be smaller at the outer positions X 1  and X 2  than at the center position Xc. 
     As a result, as illustrated in  FIG. 8F , the relative dielectric constant ε r  of the dielectric member  30  becomes higher at the outer positions X 1  and X 2  than at the center position Xc. 
     In this case, the plasma density Cp is also made uniform in the plane. 
     As described above, also in the plasma processing apparatus  120  that controls the relative dielectric constant ε r  of the dielectric member  30  by the pressure Fd applied to the dielectric member  30 , the plasma density Cp can be made uniform in the plane. 
     Moreover, as described in relation with  FIGS. 6A to 6D , according to the plasma processing apparatus  120 , the plasma density Cp can be controlled to any characteristic. Thereby, more desirable processing can be realized. 
     Also, in the plasma processing apparatus  120 , the cover member  32  described in relation with  FIG. 5A  and/or the temperature control section  12  described in relation with  FIG. 5B  may be further provided. Also, as described in relation with  FIG. 5C , the dielectric member  30  and the control unit  40  may be provided between the first electrode  10  and the position where the wafer  60  (an object to be processed) is disposed. For example, the dielectric member  30  and the control unit  40  that controls the pressure may be buried in the wafer holding section  11  of the ESC  15 . 
       FIG. 9  is a schematic cross-sectional view illustrating the configuration of another plasma processing apparatus according to the first embodiment. 
     As illustrated in  FIG. 9 , a plasma processing apparatus  130  according to the embodiment is an inductively coupled plasma processing apparatus. 
     In this case, the first electrode  10  is provided inside the processing chamber  5 , and the second electrode  20  is provided outside the processing chamber  5 . The second electrode  20  surrounds the upper part of the processing chamber  5  in the X-Y plane 
     A high-frequency power source  71  is connected to the second electrode  20 . The second electrode  20  functions as an antenna. 
     By high-frequency power supplied to the second electrode  20 , plasma is generated in the space  50  between the first electrode  10  and the second electrode  20 . 
     In this case as well, the dielectric member  30  is provided between the first electrode  10  and the second electrode  20 . And, the control unit  40  that changes the relative dielectric constant of the dielectric member  30  in the plane crossing the direction from the first electrode  10  to the second electrode  20  is provided. 
     In this specific example, the dielectric member  30  and the control unit  40  are disposed above the position where the wafer  60  is disposed (on the side of the second electrode  20 ). But in the plasma processing apparatus  113 , the dielectric member  30  and the control unit  40  may be provided between the first electrode  10  and the position where the wafer  60  is disposed. 
     In this specific example, the dielectric member  30  and the control unit  40  have linear shapes extending in the X-Y plane 
     In the ICP type plasma processing apparatus, too, by changing the relative dielectric constant ε r  of the dielectric member  30  by the control unit  40  in the plane of the dielectric member  30 , the plasma density Cp can be brought into a desirable state (uniform in the plane, for example). 
     Second Embodiment 
       FIG. 10  is a flowchart illustrating a plasma processing method according to a second embodiment. 
     As illustrated in  FIG. 10 , the plasma processing method according to the embodiment is provided with a first process (Step S 110 ). In the first process, a first plasma is generated in the space  50  between the first electrode  10  and the second electrode  20 , and the wafer  60  (an object to be processed) is processed by the first plasma. The first plasma is generated with a first distribution of the relative dielectric constant ε r  of the dielectric member  30 , which is provided between the first electrode  10  and the second electrode  20 . In the first distribution, the relative dielectric constant is changed in a plane crossing the direction from the first electrode  10  to the second electrode  20 . 
     For example, by changing at least one of the temperature of the dielectric member  30  and the pressure applied to the dielectric member  30  in the plane of the dielectric member  30 , the relative dielectric constant ε r  of the dielectric member  30  is changed in the plane of the dielectric member  30 . As a result, the density Cp of the generated plasma can be controlled to a desired state, and desired processing can be realized. For example, the plasma density Cp can be made uniform in the plane, and uniform processing in the plane can be realized. 
     The plasma processing method according to the embodiment can be applied to processing including at least one of etching using plasma and film formation. 
       FIG. 11  is a flowchart illustrating another plasma processing method according to a second embodiment. 
     As illustrated in  FIG. 11 , a plasma processing according to the embodiment is further provided with a second process (Step S 120 ). In the second process, a second plasma is generated in the space  50 , and the wafer  60  is processed by the second plasma. The second plasma is generated with a second distribution of the relative dielectric constant ε r  of the dielectric member  30 . The second distribution is different from the first distribution. 
     That is, in this processing method, in the first process and the second process, the in-plane distribution of the relative dielectric constant ε r  of the dielectric member  30  is made different from each other, and the processing is performed. 
       FIGS. 12A and 12B  are schematic views illustrating operations of another plasma processing method according to the second embodiment. 
     That is,  FIG. 12A  illustrates the in-plane distribution of the relative dielectric constant ε r  in the first process (first distribution  141 ), and  FIG. 12B  illustrates the in-plane distribution of the relative dielectric constant ε r  in the second process (second distribution  142 ). In these figures, the horizontal axis is the position along the X-axis direction and the vertical axis is the relative dielectric constant ε r  of the dielectric member  30 . 
     As illustrated in  FIGS. 12A and 12B , the second distribution  142  of the relative dielectric constant ε r  in the second process is different from the first distribution  141  of the relative dielectric constant ε r  in the first process. By making the in-plane distribution of the relative dielectric constant ε r  different from each other as above, the in-plane distribution of the plasma density Cp can be made different from each other. As a result, processing in a more desirable state can be realized. 
     For example, the first process and the second process may be initial process and second-half process in one plasma processing. This method is adopted if a more desirable processing result can be obtained by changing the distribution of the plasma density Cp between the initial processing and the second-half processing. 
     Also, it may be configured that the first process is processing for the first wafer and the second process is processing for another wafer  60 . For example, a history of processing is different between the first wafer  60  and the second wafer  60 . Also, the configuration (material, thickness, pattern and the like of a metal layer, a semiconductor layer and an insulating layer) is different between the first wafer  60  and the second wafer  60 . At this time, processing can be performed under a plasma condition suitable for the respective wafers  60 , and a more desirable processing can be performed. Thus, process flexibility can be improved. 
     The plasma processing method according to the embodiment can be put into practice using any of the plasma processing apparatuses described in relation with the first embodiment or a plasma processing apparatus of their variation, for example. According to the plasma processing apparatus according to the embodiment, the distribution of the relative dielectric constant ε r  in the dielectric member  30  can be easily controlled by the control unit  40  without changing the material of the dielectric member  30 . Plasma conditions different between the first process and the second process can be created easily. 
     According to the plasma processing apparatus and the plasma processing method according to the embodiment, the plasma density Cp can be controlled to a desired state, for example, which is particularly effective in obtaining high in-plane uniformity in plasma with a large area. And the distribution of the plasma density Cp can be changed in the process or between processes, for example, and more desirable processing can be performed. 
     The plasma processing apparatus and the plasma processing method according to the embodiment can be applied to processing of an object to be processed having a 300 mm size, processing of an object to be processed having a 450 mm size and processing of a next-generation object to be processed having a larger size, for example. The apparatus and the method can be applied to any processing such as processing including etching and film formation on a silicon substrate (wafer), a substrate of SOI (Silicon On Insulator) and a substrate of a compound semiconductor, processing of amorphous silicon film formation for solar cell with a large area, processing of etching and film formation in flat panel displays with a large area and the like. 
     As described above, according to the embodiment, a plasma processing apparatus and a plasma processing method with excellent controllability of the plasma density are provided. 
     The embodiments of the invention have been described above by referring to the specific examples. However, the embodiments of the invention are not limited by these specific examples. For example, regarding the specific configuration of each element such as the first electrode, the second electrode, the dielectric member, the control unit, the processing chamber, the ESC, the wafer holding section, the temperature control section, the cover member, the driving section, the high-frequency power source and the like included in the plasma processing apparatus are contained in the range of the invention as long as those skilled in the art can carry out the invention similarly and obtain the similar advantages by making selection from a known range as appropriate. 
     Also, those obtained by combining any two or more or elements of each specific example in a technically feasible range are also contained in the range of the invention as long as the gist of the invention is contained. 
     And all the other plasma processing apparatuses and plasma processing methods that can be carried out by those skilled in the art with appropriate design change on the basis of the plasma processing apparatus and the plasma processing method described above as the embodiments of the invention also belongs to the range of the invention as long as the gist of the invention is contained. 
     The other variations and modifications in the scope of the idea of the invention that could have been easily conceived of by those skilled in the art are also understood to belong to the range of the invention. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modification as would fall within the scope and spirit of the inventions.