Abstract:
A plasma processing apparatus includes a chamber, substrate stage, electrode, conductive members, and deposition shield. The chamber is maintained at a predetermined potential. The substrate stage serves to hold a substrate within the chamber. The electrode serves to generate a plasma inside the chamber by applying AC power to the chamber. The conductive members connect the substrate stage and the side wall of the chamber by surrounding the plasma space between the substrate stage and the electrode in plasma formation, and at least some of them are separated by being moved by a driving mechanism so as to form an opening for loading a substrate onto the substrate stage while no plasma is being formed. The deposition shield covers the surfaces of the conductive members on the side of the plasma space.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a plasma processing apparatus including a chamber which accommodates a deposition shield, and an electronic device manufacturing method. 
       BACKGROUND ART 
       [0002]    Conventionally, a plasma processing apparatus such as a sputtering apparatus includes a vacuum chamber which accommodates a deposition shield that surrounds the plasma generation space so as to prevent sputtered particles and other particles from adhering onto the inner wall of the vacuum chamber and shield the plasma generation space against these particles. Patent reference 1 discloses an example of a sputtering apparatus including a conductive deposition shield. 
         [0003]    As shown in patent reference 1, a deposition shield is divided and formed to be openable/closable so as to load a substrate onto a substrate stage at the time of substrate loading. If the deposition shield is completely closed in the division portions after the substrate loading, the film which has adhered onto the surface of the deposition shield peels off due to, e.g., vibration upon opening/closing, thus generating particles. To prevent this, the division portions are maintained in a noncontact state with gaps (1 mm or less) between them, that are narrow enough not to leak the plasma. 
       CITATION LIST 
     Patent Literature 
       [0004]    Patent reference 1: Japanese Patent Laid-Open No. 2002-356771 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    However, when a deposition shield is repeatedly used in a process chamber, the adhering film deposits on its shield surface. For this reason, as the amount of deposition increases, the conductive deposition shield is replaced. Nevertheless, because discharge is also performed between the discharge electrode and the conductive deposition shield, the discharge characteristics change when the dimension and shape of the deposition shield differ before and after the replacement. This problem is especially serious in high-frequency discharge. In this case, a current is conducted even to the gaps, so the adverse effect of changes in the above-mentioned gaps due to a change in dimension of the deposition shield is non-negligible; the plasma generation state or the substrate stage potential state changes before and after the replacement or differ for each position. As a result, deposition which uses, for example, sputtering leads to variations in the deposition results such as the film thickness and composition. 
       Solution to Problem 
       [0006]    The present invention has been made in consideration of the above-mentioned problems, and has as its object to provide a plasma processing apparatus which can obtain stable deposition results even when a deposition shield is replaced. 
         [0007]    In order to achieve the above-mentioned object, according to the present invention, there is provided a plasma processing apparatus comprising: 
         [0008]    a chamber; 
         [0009]    a substrate stage configured to hold a substrate within the chamber; 
         [0010]    an electrode configured to generate a plasma inside the chamber; and 
         [0011]    a shield member formed to surround a plasma space between the electrode and the substrate stage, 
         [0012]    wherein the shielding member comprising: 
         [0013]    a main body part; and 
         [0014]    a separated part formed by dividing the main body part, 
         [0015]    wherein the main body part and the separated part each including an inner portion and an outer portion positioned outside the inner portion with respect to the plasma space, 
         [0016]    the outer portions of the main body part and the separated portions are conductive members and are formed to be able to connect the chamber and the substrate stage through contact with each other, and 
         [0017]    the inner portions of the main part and the separated part are formed so as not to be in contact with each other. 
       Advantageous Effects of Invention 
       [0018]    According to the present invention, it is possible to provide a plasma processing apparatus which can obtain stable deposition results even when a deposition shield is replaced. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
           [0020]      FIG. 1  is a view showing the schematic arrangement of a sputtering apparatus according to one embodiment of the present invention; 
           [0021]      FIG. 2  is an enlarged view of a deposition shield and outer member shown in  FIG. 1 ; 
           [0022]      FIG. 3  is a view showing the state (open state) in which a middle deposition shield and middle outer member have been moved to the lower positions in the vertical direction from the state (closed state) shown in  FIGS. 1 and 2 ; and 
           [0023]      FIG. 4  is a view showing another embodiment of the sputtering apparatus shown in  FIG. 1 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0024]    An embodiment of the present invention will be described below with reference to the accompanying drawings. 
         [0025]    In this embodiment, a capacity coupling type sputtering apparatus will be explained as one example of plasma processing apparatuses.  FIG. 1  is a view showing the schematic arrangement of a sputtering apparatus according to one embodiment of the present invention. 
         [0026]    The sputtering apparatus shown in  FIG. 1  includes a vacuum chamber  103  in which a supply hole  101  connected to a gas introduction system for, e.g., a discharge gas and a process gas, and an exhaust hole  102  connected to an exhaust system including a roughing pump and a main pump are formed. The vacuum chamber  103  includes a transport port  114  serving as an opening for loading a substrate to be processed into the vacuum chamber  103  and unloading the processed substrate from the vacuum chamber  103 . This embodiment exemplifies a cluster type plasma processing apparatus which is connected to a substrate transport chamber including a substrate transport robot and exchanges a substrate with the robot in the substrate transport chamber. Note that the vacuum chamber  103  is formed in a roughly cylindrical shape. 
         [0027]    The vacuum chamber  103  accommodates a stage  104  which can mount a substrate that undergoes a deposition process, and a target electrode  105  which faces the substrate. The target electrode  105  is connected to a DC power supply  113  which generates a DC voltage, and an AC power supply  112  which generates high-frequency power (AC power). The DC power and AC power supplied from these power supplies into the vacuum chamber  103  produce a plasma from the discharge gas introduced into the vacuum chamber  103 . The vacuum chamber  103  also accommodates a shield member which surrounds a plasma space formed between the target electrode  105  and the stage  104 . The shield member includes a deposition shield  200  (corresponding to an inner portion), and an outer member  300  (corresponding to an outer portion) which surrounds the exterior of the deposition shield  200 . 
         [0028]    The deposition shield  200  in this embodiment has a roughly cylindrical cross-section as a whole and is divided into three parts in the height direction. The deposition shield  200  includes an upper deposition shield part  201 , middle deposition shield part  202 , and lower deposition shield part  203 . The upper deposition shield part  201 , middle deposition shield part  202 , and lower deposition shield part  203  (to be also simply referred to as the “deposition shield parts  201  to  203 ” hereinafter) are configured to integrally surround the plasma space within the vacuum chamber  103 . The deposition shield parts  201  to  203  are made of a conductive member such as stainless steel or aluminum. The shield surfaces of the deposition shield parts  201  to  203  exposed to the plasma space side within the vacuum chamber  103  have fine three-dimensional patterns formed on them by Al spraying or blasting in order to prevent peel-off of the sputtered thin films which have adhered onto the shield surfaces once. 
         [0029]      FIG. 2  is an enlarged view of the deposition shield parts  201  to  203  and outer member  300  shown in  FIG. 1 . 
         [0030]    The ranges, in which the fine three-dimensional patterns are formed, on the shield surfaces of the deposition shield parts  201  to  203  are indicated by bold lines in  FIG. 2 . The deposition shield parts  201  to  203  are spaced apart from each other with gaps S 1  and S 2  between them so as not to be in contact with each other to prevent them from colliding with each other upon an opening/closing operation (to be described later). The gaps S 1  and S 2  are preferably about 1.5 to 3 mm. In this case, it is possible to reduce the adverse effect of current conduction across the gaps S 1  and S 2  and to effectively prevent the sputtered particles from adhering onto the outer member  300 . 
         [0031]    In this embodiment, the gaps S 1  and S 2  are formed in a labyrinth shape so as to prevent the sputtered particles from readily moving outside the deposition shield  200  via the gaps S 1  and S 2 . This makes it possible to increase the length of the path from one end of each of the gaps S 1  and  52  to the other end of each of the gaps S 1  and S 2  and, in turn, to reduce the possibility that the particles reach outside the deposition shield  200  via the gaps S 1  and S 2 . 
         [0032]    The outer member  300  has a shape which surrounds the exterior of the deposition shield  200 , and includes an upper outer member  301 , middle outer member  302 , and lower outer member  303 . The upper outer member  301 , middle outer member  302 , and lower outer member  303  (to be also simply referred to as the “members  301  to  303 ” hereinafter) are made of a conductive material such as aluminum or stainless steel. The middle outer member  302  and middle deposition shield part  202  correspond to a third member in the present invention, the upper outer member  301  and upper deposition shield part  201  correspond to a second member in the present invention, and the lower outer member  303  and lower deposition shield part  203  correspond to a first member in the present invention. 
         [0033]    Of the above-mentioned members, the lower outer member  303  includes a support portion  303   a  and an annular connecting portion  303   b  supported by the support portion  303   a,  as shown in  FIG. 2 . The lower deposition shield part  203  is detachably attached to the connecting portion  303   b  by a bolt Bt 1 , and the connecting portion  303   b  and lower deposition shield part  203  are electrically connected to each other by surface contact. The lower deposition shield part  203  is also detachably attached to the stage  104  by a bolt Bt 2 , and the lower deposition shield part  203  and the stage  104  are electrically connected to each other by surface contact. Hence, a current flows from the stage  104  to the lower outer member  303  through the lower deposition shield part  203  during discharge. Note that the support portion  303   a  and the stage  104  are grounded (see  FIG. 1 ). 
         [0034]    The middle outer member  302  includes a roughly cylindrical vertical connecting portion  302   a  extending in the vertical direction and a horizontal connecting portion  302   c  extending in the horizontal direction. Also, the middle outer member  302  is connected to a driving shaft  401  so as to be moved in the vertical direction by a driving means such as a cylinder (not shown). When the middle outer member  302  has been moved to the upper position in the vertical direction, the horizontal connecting portion  302   c  is in contact with the lower surface of the lower outer member  303  (a contact portion D shown in  FIG. 2 ), and the upper end face of the vertical connecting portion  302   a  is in contact with the upper outer member  301  (a contact portion B shown in  FIG. 2 ), as shown in  FIG. 2 . 
         [0035]    A stepped portion  302   b  is formed in the upper portion of the vertical connecting portion  302   a  at a level lower than the upper end face of the vertical connecting portion  302   a  in the vertical direction. The middle deposition shield part  202  is detachably attached to the middle outer member  302  by a bolt (not shown) so that the middle deposition shield part  202  abuts against the stepped portion  302   b.  The middle deposition shield part  202  moves as the middle outer member  302  is moved by the driving shaft  401 . When the middle deposition shield part  202  has been moved to the upper position in the vertical direction (closed state), the middle deposition shield part  202  forms the above-mentioned noncontact gaps S 1  and S 2  with lower deposition shield part  203  and the upper deposition shield part  201 , respectively, as the remaining deposition shield parts. The inner peripheral surface of the vertical connecting portion  302   a  need not always be in contact with the outer peripheral surface of the middle outer member  302 . It is rather preferable to form a narrow gap between these peripheral surfaces by taking account of, e.g., thermal expansion attributed to heat applied to them during process steps involved. 
         [0036]    When the middle deposition shield part  202  has been moved to the upper position in the vertical direction (closed state), as shown in  FIG. 2 , the current which has flowed from the stage  104  to the lower outer member  303  flows to the middle outer member  302  through the contact portion D during discharge. Also, the current generated due to a change in voltage across the middle deposition shield part  202  and the target electrode  105  flows from the middle deposition shield part  202  to the middle outer member  302 . 
         [0037]    The upper outer member  301  includes a roughly cylindrical vertical connecting portion  301   a  extending in the vertical direction from the middle outer member  302  toward the side wall (chamber side wall) of the vacuum chamber  103 , and a horizontal connecting portion  301   b  extending in the horizontal direction in the upper portion of the vertical connecting portion  301   a.  The horizontal connecting portion  301   b  is detachably attached to the vacuum chamber  103  through a bolt Bt 3  by abutting the lower end face of the horizontal connecting portion  301   b  against the stepped portion formed on the side wall of the vacuum chamber  103 . Also, the upper deposition shield part  201  is detachably attached to the horizontal connecting portion  301   b  through a bolt Bt 4  by abutting the portion, extending in the horizontal direction, of the upper deposition shield part  201  against the upper end face of the horizontal connecting portion  301   b.    
         [0038]    With this arrangement, when the middle deposition shield part  202  is closed, as shown in  FIG. 2 , the current which has flowed from the stage  104  to the middle outer member  302  flows to the upper outer member  301  through the contact portion D during discharge. Also, the current generated due to a change in voltage across the upper deposition shield part  201  and the target electrode  105  flows from the upper deposition shield part  201  to the upper outer member  301 . 
         [0039]    The lower deposition shield part  203  is configured by detachably attaching an upper shield plate  203   a  and lower shield plate  203   b  to each other by a bolt Bt 5  by vertically stacking them with a narrow gap between them. Slits L 1  and L 2  are formed in the upper shield plate  203   a  and lower shield plate  203   b,  respectively, at positions offset from each other. The slits L 1  and L 2  can form a labyrinth-shaped ventilation duct together with the gap between the upper shield plate  203   a  and the lower shield plate  203   b.  The slit L 2  formed in the lower shield plate  203   b  runs through the lower outer member  303 . 
         [0040]    The operation of the sputtering apparatus according to the embodiment will be explained next with reference to  FIGS. 1 to 3 .  FIG. 3  is a view showing the state (open state) in which the middle deposition shield part  202  and middle outer member  302  have been moved to the lower positions in the vertical direction from the state (closed state) shown in  FIGS. 1 and 2 . In the open state, the middle outer member  302  is spaced apart (separated) from the upper outer member  301  and lower outer member  303 . 
         [0041]    In the closed state shown in  FIG. 1 , the middle outer member  302  seals the transport port  114 . However, a substrate (not shown) can be transported through the transport port  114  by moving the middle deposition shield part  202  and middle outer member  302  downward in the vertical direction, as shown in  FIG. 3 . The substrate is transported into the vacuum chamber  103  through the transport port  114  and fixed on the stage  104 . 
         [0042]    After that, the middle deposition shield part  202  and middle outer member  302  are moved upward in the vertical direction to close the transport port  114 . A discharge gas is introduced into the vacuum chamber  103 , and then high AC (e.g., 13.56 MHz to 100 MHz) and DC voltages are applied to the target electrode  105  to produce a plasma from the discharge gas. In this way, while the vacuum chamber  103  applied with power from the AC power supply  112  and DC power supply  113  is maintained at a predetermined potential, the driving shaft  401  and the cylinder maintain the upper outer member  301 , middle outer member  302 , and lower outer member  303  at the positions where the middle outer member  302  comes into contact with the upper outer member  301  and lower outer member  303 . Further, the middle outer member  302  and the upper outer member  301  and lower outer member  303  are electrically connected to the vacuum chamber  103 . 
         [0043]    Hence, currents supplied from the AC power supply  112  and DC power supply  113  flow to the earth upon passing through the stage  104 , the outer member  300 , and the side wall of the vacuum chamber  103 , as described above, through the plasma. The current generated in the deposition shield  200  flows to the earth upon passing through the outer member  300  and the side wall of the vacuum chamber  103 . In this manner, since the outer member  300  which does not require replacement forms a return circuit, it is possible to prevent a change in electrical characteristic of the deposition shield  200  attributed to its replacement and, in turn, to stabilize the deposition characteristic of a film formed on the substrate. 
         [0044]    In this embodiment, the outer member  300  surrounds the overall exterior of the deposition shield  200  although this feature is not always indispensable for the present invention. With this arrangement, the outer member  300  also functions as a double shield, and this makes it possible to more reliably prevent any plasma leakage. The gaps between the constituent members  301  to  303  of the outer member  300  are preferably set to 0.1 mm (inclusive) to 1 mm (inclusive) because this makes it possible to more effectively prevent any plasma leakage. 
         [0045]    Moreover, the conductance can be increased from 20 to 50 L/s corresponding to a conventional single deposition shield to 100 to 200 L/s by forming the slits L 1  and L 2  at positions offset from each other, as shown in  FIG. 2 . 
         [0046]    Also, this embodiment has exemplified an arrangement which moves the middle deposition shield part  202  and middle outer member  302  throughout the entire circumferential portion of the vacuum chamber  103 . With this arrangement, a joint is uniformly formed between the middle deposition shield part  202  and the lower deposition shield part  203  in the circumferential direction of the stage  104 . A gap serving as a shield joint is likely to become a singularity in the plasma distribution due to, e.g., entrance of the plasma into the gap and this causes nonuniformity of the plasma distribution. However, it is possible to uniform the plasma distribution and, in turn, to uniform the in-plane distribution of the deposition characteristic by uniformly forming a joint between the middle deposition shield part  202  and the lower deposition shield part  203  in the circumferential direction of the stage  104 . Nevertheless, an arrangement which moves the middle deposition shield part  202  and middle outer member  302  throughout the entire circumferential portion of the vacuum chamber  103  is not always indispensable. For example, an arrangement which can vertically move only a portion required to transport a substrate through the transport port  114  may be adopted. 
         [0047]    Moreover, the following advantages can be gained by moving the middle deposition shield part  202  and middle outer member  302  to allow substrate transport through the transport port  114 , as in this embodiment. That is, an arrangement which moves the middle deposition shield part  202  and middle outer member  302  as in this embodiment obviates the need for a lift mechanism for lifting/lowering the stage  104 . If an arrangement which lifts/lowers the stage is adopted, the stage is grounded through a lift mechanism such as a bellows. In contrast, if an arrangement which lifts/lowers the stage is not adopted, grounding through a lift mechanism is unnecessary and this facilitates stabilization of the potential of the stage at the time of grounding. This makes it possible to further stabilize the deposition characteristic. 
         [0048]    However, the present invention is not limited to an arrangement which can transport a substrate through the transport port  114  by moving the middle deposition shield part  202  and middle outer member  302 . An arrangement which can load a substrate by lifting/lowering the stage  104  using a lift mechanism may be adopted, as shown in  FIG. 4 . A substrate may be loaded from the transport port  114  into the vacuum chamber  103  when the stage  104  is lowered to the lower end, and the stage  104  may be lifted after the substrate is placed on the stage  104 . 
         [0049]    Also, although  FIG. 1  exemplifies a case in which the stage  104  is located below the target electrode  105 , the present invention is not limited to this. An arrangement in which a target electrode is located on the lower side within a vacuum chamber and a stage which holds a substrate is located above the target electrode may be adopted. 
         [0050]    Moreover, although this embodiment has exemplified an arrangement in which the middle outer member  302  is connected to the driving shaft  401  and moved by a driving means such as a cylinder (not shown), an arrangement which moves the upper outer member  301  and lower outer member  303  may be adopted instead. Alternatively, an arrangement which independently moves the middle outer member  302  and the upper outer member  301  and lower outer member  303  may be adopted. 
         [0051]    Further, the inner portion is not always necessary in the present invention. For example, the present invention may be embodied as the following plasma processing apparatus. The apparatus includes a chamber, a substrate stage for holding a substrate within the chamber, an electrode for generating a plasma inside the chamber, and a conductive shield member formed to surround the plasma space between the electrode and the substrate stage. The shield member includes a first member on the side of the substrate stage, a second member on the side of the chamber, which is spaced apart from the first member, and a third member formed in an annular shape that surrounds the exterior of the substrate stage between the first member and the second member. The third member is formed to be able to connect the chamber and the substrate stage through contact with the first member and the second member. The apparatus further includes a driving means for moving the third member between the closed position and the open position where the plasma space is open. In this case, since the shield member is driven instead of driving the substrate stage, it is possible to stabilize the grounding state of the substrate stage and, in turn, to uniform the in-plane electrical characteristic. In addition, since the contact portions between the third member and the remaining members are uniformed around the substrate periphery, it is possible to uniform the in-plane conditions such as the plasma distribution and the stage potential in this respect as well. 
         [0052]    (Application to Electronic Device Manufacturing Method) 
         [0053]    The plasma processing apparatus according to the embodiment of the present invention is applicable to a deposition process for manufacturing, for example, an electronic device such as a large-screen flat panel display (liquid crystal display), a thin-film solar battery panel, a microinductor, or a magnetic recording head, or a memory device, which uses a magnetic thin film, such as an MRAM (Magnetoresistive Random Access Memory). 
         [0054]    Although a preferred embodiment of the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to this embodiment, and can be changed into various forms within the technical scope understood from the claims. 
         [0055]    This application claims priority based on Japanese Patent Application No. 2008-197582, filed Jul. 31, 2008, which is hereby incorporated by reference herein in its entirety.