Patent Publication Number: US-2017352573-A1

Title: Substrate processing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2016-113501, filed on Jun. 7, 2016, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     The present application relates to a substrate processing apparatus. 
     Chemical mechanical polishing (CMP) apparatuses are known as apparatuses for polishing substrate surfaces in manufacturing semiconductor devices. In a CMP apparatus, a polishing pad is stuck to a top surface of a polishing table to form a polishing surface. This CMP apparatus pushes a surface to be polished of a substrate held by a top ring against the polishing surface and rotates the polishing table and the top ring while supplying slurry as a polishing liquid to the polishing surface. This causes the polishing surface and the surface to be polished to relatively move slidably, and the surface to be polished is thereby polished. 
     Regarding flattening techniques including CMP, there are a wide variety of materials to be polished and requirements for polishing performance (e.g., flatness, polishing damage, and further productivity) are becoming stricter in recent years. With an introduction of more refined semiconductor devices, there is a growing demand for polishing performance and cleanliness in CMP apparatuses. 
     Under such circumferences, substrates may be processed using polishing pads smaller in size than the substrates to be processed in the CMP apparatuses (e.g., U.S. Pat. No. 6,561,881). Generally, a polishing pad smaller in size than a substrate to be processed can flatten locally generated unevenness on a substrate, polish only specific parts of the substrate or adjust the amount of polishing in accordance with the position of the substrate, and provides excellent controllability. 
     On the other hand, new flattening methods are also being proposed, and a catalyst referred etching (hereinafter, referred to as “CARE”) method is one such example. In the presence of a processing liquid, the CARE method generates a seed of reaction with a surface to be polished from within the processing liquid only in the vicinity of a catalyst material, causes the catalyst material and the surface to be polished to come closer to or come into contact with each other, and can thereby selectively make etching reaction occur on the surface to be polished (e.g., WO2015/159973, pamphlet). For example, with an uneven surface to be polished, selective etching of convex parts is made possible by causing the convex parts and the catalyst material to come closer to or come into contact with each other and it is possible to further flatten the surface to be polished. 
     Furthermore, a polishing speed and an etching speed of a substrate depend on a temperature of a region where the surface of a substrate and a pad come into contact with each other. Therefore, in order to flatten the substrate accurately, it is desirable to control the temperature of the region where the surface of the substrate and the pad come into contact with each other. 
     In a polishing apparatus that polishes a substrate surface from above, the substrate is held from below by means of vacuum suction using a rotatable table. Conventionally, a table that holds a substrate has a groove pattern for suctioning formed on the surface of a flat table, the substrate is directly placed on the table and vacuum-suctioned. Therefore, a non-flat part of the table may affect the substrate placed thereon and affect flatness of the surface of the polished substrate. For example, when the substrate is vacuum-suctioned to the table, the substrate does not come into contact with the non-flat part of the table. For this reason, a gap may be produced between the table and the substrate, air may leak from the gap and the suction rate of the substrate may decrease. Furthermore, since the material used for the table is generally a high hardness material, the reverse side of the substrate contacting the table is susceptible to damage. On the other hand, to reduce damage to the reverse side of the substrate, the table may be made of resin which has relatively low hardness, but a resin-made table generally has poor flatness. 
     With the CARE method and CMP, a processing speed (polishing speed, etching speed) of a wafer Wf generally depends on a temperature of a substrate surface to be processed. Therefore, to control the temperature of the substrate surface to be processed, a temperature-adjusted chemical solution or pure water may be supplied to the substrate surface so as to adjust the surface temperature of the substrate through heat exchange between the liquid and the substrate. However, since the temperature-adjusted chemical solution or pure water is supplied to the substrate surface through a channel, the temperature of the liquid reaching the substrate surface may be different from a set temperature depending on its environment. Furthermore, since the chemical solution or pure water remains in the channel, even when the set temperature of the liquid is changed, the temperature of the liquid supplied to the substrate does not immediately change. Furthermore, the temperature of the substrate surface may exceed the set temperature (overshoot) or fall below the set temperature (undershoot) due to heat accumulation of the table. Furthermore, the closer to a supply port of the temperature-adjusted liquid a portion of the substrate is, the greater the effect of temperature adjustment becomes and the less likely it is for a temperature distribution of the substrate surface to become uniform. Moreover, it is not possible to control the temperature distribution of the substrate surface and it is difficult to control the substrate temperature. 
     It is an object of the present invention to mitigate or solve at least some of the above-described problems. 
     SUMMARY 
     According to a first aspect, a substrate processing apparatus is provided. The substrate processing apparatus includes a table for holding a substrate, a resin film attached to a top surface of the table and a heater provided inside the table, in which the top surface of the table is formed of ceramics, the top surface of the table defines an opening connectable to a vacuum source, the resin film is formed of polyimide, and the resin film define a through hole at a position corresponding to the opening of the table when the resin film is attached to the top surface of the table. According to such an aspect, it is possible to form a flat table using a ceramic, high hardness material, and support the substrate via a relatively less hard resin film to thereby reduce a possibility of damaging the substrate while maintaining high flatness of the top surface of the table. Furthermore, the resin-made film is less hard than the table and deformable to a certain degree, and it is thereby possible to improve a state of contact between the table and the substrate and suppress air leakage during vacuum suctioning. It is also possible to control the temperature of the substrate surface to be processed and control the substrate processing speed using a heater. It is also possible to control hardness of the resin-made film using the heater. 
     According to a second aspect, the substrate processing apparatus according to the first aspect includes a temperature sensor to measure a surface temperature of the substrate held on the table. According to such an aspect, it is possible to measure the surface temperature of the substrate using the temperature sensor, and thereby control the surface temperature of the substrate so that the substrate surface has an optimum temperature. 
     According to a third aspect, the substrate processing apparatus according to the second aspect includes a controller that can communicate with the temperature sensor and the heater, and the controller is configured so as to control the heater based on the temperature measured by the temperature sensor. According to such an aspect, the controller can perform control so that the substrate surface has a desired temperature. 
     According to a fourth aspect, in the substrate processing apparatus according to the third aspect, the table includes a plurality of regions, the heater includes a plurality of heaters arranged at positions corresponding to the plurality of regions of the table and the controller is configured so as to control the plurality of heaters independently of each other. According to such an aspect, it is possible to form a desired temperature distribution on the substrate surface and control a substrate processing speed for each region. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is schematic plan view of a substrate processing apparatus of a substrate processing system as an embodiment; 
         FIG. 2  is a schematic side view of the substrate processing apparatus according to the embodiment; and 
         FIG. 3  is a schematic side view of a substrate processing apparatus according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of a substrate processing apparatus according to the present invention will be described with reference to the accompanying drawings. In the attached drawings, identical or similar elements are assigned identical or similar reference numerals, and duplicate description relating to the identical or similar elements in the respective embodiments will be omitted. Features shown in each respective embodiment are also applicable to the other embodiments unless they are inconsistent with each other. 
       FIG. 1  is a schematic plan view of a substrate processing apparatus  10  of a substrate processing system as an embodiment. The substrate processing apparatus  10  is an apparatus that performs etching processing on a semiconductor material (region to be processed) on a substrate using a CARE method. Alternatively, the substrate processing apparatus  10  can also be configured as a CMP apparatus using a pad smaller in size than the substrate. The substrate processing system is provided with the substrate processing apparatus  10 , a substrate cleaning section (not shown) configured to clean the substrate and a substrate conveying section (not shown) that conveys the substrate. The substrate processing system may also be provided with a substrate drying section (not shown) as required. The substrate conveying section is configured to be able to convey a wet-state substrate and a dry-state substrate separately. Furthermore, depending on the type of a semiconductor material, processing through CMP may be performed using a polishing pad greater in size than a conventional substrate to be processed before or after the processing by the substrate processing apparatus  10 , and therefore the substrate processing system may be provided with a CMP apparatus further including a large-diameter polishing pad. The substrate processing system may further include a film formation apparatus such as a chemical vapor deposition (CVD) apparatus, a sputtering apparatus, a plating apparatus and a coater apparatus. In the present embodiment, the substrate processing apparatus  10  is configured as a unit separate from the CMP apparatus. Since the substrate cleaning section, the substrate conveying section and the CMP apparatus are known techniques, illustration and description thereof are omitted hereinafter. 
     The substrate processing apparatus  10  is provided with a table  20  to hold a substrate, a head  30  provided with a pad that holds a catalyst, a processing liquid supply section  40 , a swing arm  50 , a conditioning section  200  and a control section  300 . The table  20  is provided with a substrate holding surface and configured to hold a wafer Wf as a kind of substrate on the substrate holding surface. In the present embodiment, the table  20  holds the wafer Wf such that a surface to be processed of the wafer Wf faces up. In the present embodiment, the table  20  is provided with a vacuum suction mechanism including a vacuum suction plate to vacuum-suction the reverse side (surface opposite to the surface to be processed) of the wafer Wf as a mechanism to hold the wafer Wf. As a vacuum suction scheme, either one of the two schemes may be used: a point suction scheme using a suction plate including a plurality of suction holes connected to a vacuum line on the suction surface and a surface suction scheme including (e.g., concentric) grooves on the suction surface to suction the wafer through connection holes to a vacuum line provided in the grooves. However, an arbitrary publicly known mechanism can be used as the mechanism for holding the wafer Wf, and for example, a clamp mechanism that clamps the front side and the reverse side of the wafer Wf on at least one of peripheral edges of the wafer Wf or a roller chuck mechanism that holds a side face of the wafer Wf on at least one of peripheral edges of the wafer Wf may be used. Such a table  20  is configured so as to be rotatable using a drive section motor or an actuator (not shown). 
     The head  30  of the embodiment shown in  FIG. 1  is configured to hold a catalyst at a bottom end thereof. In the present embodiment, the size of the head  30  is smaller than that of the wafer Wf. That is, when an image of the head  30  is projected toward the wafer Wf, the projected area of the head  30  is smaller than the area of the wafer Wf. Furthermore, the head  30  is configured to be rotatable by a drive section, that is, an actuator (not shown). Furthermore, a motor or an air cylinder (not shown) is provided inside the swing arm  50  to move the head  30  upward or downward with respect to the wafer Wf so as to bring the catalyst of the head  30  into sliding contact with the wafer Wf. 
     The processing liquid supply section  40  is configured to supply a processing liquid PL to the surface of the wafer Wf. Here, the number of processing liquid supply sections  40  is one in  FIG. 1 , but a plurality of processing liquid supply sections  40  may be arranged, and in that case, different processing liquids may be supplied from the respective processing liquid supply sections. When the surface of the wafer Wf is cleaned in the substrate processing apparatus  10  after etching processing, a cleaning chemical solution or water may be supplied from the processing liquid supply section  40 . As another embodiment, the processing liquid supply section  40  may be configured to supply the processing liquid PL from the surface of the head  30  to the surface of the wafer Wf after passing through the swing arm  50  and the head  30 . As an embodiment, the processing liquid supply section  40  may be provided with a temperature adjustment unit for adjusting a temperature of the processing liquid so as to be able to control the temperature of the liquid supplied to the wafer Wf. 
     As shown in  FIG. 1 , the swing arm  50  is configured to be swingable around a center of rotation  51  by a drive section, that is, an actuator (not shown). Furthermore, the head  30  is configured to be movable upward or downward and able to push the head  30  against the wafer Wf. The head  30  is attached to a distal end of the swing arm  50  (end portion opposite to the center of rotation  51 ). 
     In the embodiment shown in  FIG. 1 , the control section  300  can be constructed of a general-purpose computer or a dedicated computer provided with, for example, a CPU, a storage apparatus such as a memory and an input/output apparatus. The control section  300  is connected to various components in the substrate processing apparatus  10 , stores programs to control their operations and can control operation of the entire substrate processing apparatus  10 . 
       FIG. 2  is a schematic side view of the substrate processing apparatus  10  according to the embodiment.  FIG. 2  shows a state in which the head  30  is in contact with the wafer Wf. Note that in  FIG. 2 , the mechanism for moving the head  30  upward or downward, the swing arm  50  and the processing liquid supply section  40  are omitted. The head  30  is provided with a pad  33  that comes into contact with the wafer Wf to process the wafer Wf. The pad  33  can be a pad to which a CARE catalyst is applied. Alternatively, as another embodiment, the pad can also be a pad for CMP. 
     As described above, the table  20  is configured to be rotatable. As shown in  FIG. 2 , the table  20  includes a passage  22  connected to a vacuum source (not shown). The passage  22  communicates with an opening  26  provided on a top surface  24  of the table  20 . The table  20  as a whole or at least the top surface is formed of ceramics. Ceramics is generally a high hardness material which allows a table whose top surface has a high degree of flatness compared to a material having a relatively small degree of hardness such as resin to be formed. Moreover, ceramics generally has excellent heat-resistance and is less deformed by heat. In the embodiment shown in  FIG. 2 , a resin film  28  is placed on the top surface  24  of the table  20 . As shown in  FIG. 2 , the resin film  28  is provided with a through hole  29  at a position corresponding to the opening  26  of the table  20  when placed on the top surface  24  of the table  20 . The resin film  28  can be adhered to the top surface  24  of the table  20  using, for example, a double-sided tape or may be adhered to the top surface  24  of the table  20  using an adhesive. The resin film  28  can be formed of resin having excellent heat-resistance such as polyimide. Furthermore, the resin film  28  may also be formed of polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyvinyl chloride (PVC) or the like. The resin film  28  preferably has a thickness of approximately 30 μm to approximately 500 μm to mitigate hardness of the table surface while maintaining flatness of the table. 
     As described above, the ceramic table  20  can attain a table whose top surface  24  has a high degree of flatness, but since it has high hardness, when the wafer Wf is directly placed on the table  20 , the wafer Wf may be damaged. In the embodiment in  FIG. 2 , since the resin film  28  less hard than ceramics is placed on the top surface  24  of the table  20 , it is possible to reduce a possibility of damaging the wafer Wf while maintaining high flatness of the top surface of the table  20 . 
       FIG. 3  is a schematic side view of the substrate processing apparatus  10  according to another embodiment. The table  20  of the substrate processing apparatus  10  according to the embodiment shown in  FIG. 3  is provided with a heater  100  at a position below the top surface  24 . The heater  100  can be placed over substantially the whole surface of the table  20  except the portions of the passages  22  in the table  20 . The heater  100  is configured so as to be controlled by the control section  300 . The heater  100  may also be divided into a plurality of regions in the table  20  and arranged, and configured to be separately controllable for each divided region. It is thereby possible to control a temperature distribution on the surface of the wafer Wf. The heater  100  can be formed of a common heating wire. For example, when the ceramic table  20  is manufactured, by embedding the heating wire therein, it is possible to manufacture the table  20  with the heater  100  embedded therein. 
     In the embodiment shown in  FIG. 3 , the substrate processing apparatus  10  includes a temperature sensor  150 . The temperature sensor  150  can be, for example, a non-contact type temperature sensor such as a thermography or infrared sensor. The temperature sensor  150  is placed so as to be able to measure a temperature of the surface of the wafer Wf. For example, the temperature sensor  150  may be held by a moving mechanism (not shown) and configured to be able to scan the surface of the wafer Wf. The temperature sensor  150  is connected to the control section  300 . The control section  300  controls the heater  100  based on temperature information on the surface of the wafer Wf received from the temperature sensor  150  during processing on the wafer Wf. 
     According to the CARE method or CMP, the processing speed of the wafer Wf (polishing speed, etching speed) depends on the temperature of the surface of the wafer Wf. In the embodiment shown in  FIG. 3 , it is possible to control the temperature of the surface of the wafer Wf using the heater  100  placed in the table  20 . In such an embodiment, it is possible to adjust the temperature of the surface of the wafer Wf more speedily than the case with temperature control of the surface of the wafer Wf through the aforementioned processing liquid. Furthermore, the whole surface of the table  20  can be heated uniformly using the heater  100 , it is thereby possible to uniformly heat the surface of the wafer Wf. Furthermore, it may be possible to divide the surface of the table  20  into a plurality of regions, arrange the heater  100  for each divided region and perform temperature control independently for each divided region. By performing temperature control independently for each divided region, it is possible to change the processing speed (polishing speed, etching speed) for each divided region and control the processing on the wafer Wf more accurately. Since the temperature sensor  150  directly measures the temperature of the surface of the wafer Wf, it is possible to measure the temperature of the surface of the wafer Wf accurately compared to cases of measuring the temperature in the table  20  or the temperature of the processing liquid. Furthermore, in the embodiment shown in  FIG. 3 , since the resin film  28  placed on the top surface  24  of the table  20  is also heated by the heater  100 , it is possible to control hardness of the resin film  28 . 
     DESCRIPTION OF THE NUMERALS 
     
         
         
           
               10  . . . Substrate processing apparatus 
               20  . . . Table 
               22  . . . Passage 
               24  . . . Top surface 
               26  . . . Opening 
               28  . . . Resin film 
               29  . . . Through hole 
               30  . . . Head 
               33  . . . Pad 
               40  . . . Processing liquid supply section 
               50  . . . Swing arm 
               51  . . . Center of rotation 
               100  . . . Heater 
               150  . . . Temperature sensor 
               200  . . . Conditioning section 
               300  . . . Control section 
             Wf . . . Wafer 
             PL . . . Processing liquid