Abstract:
An ion implant apparatus configured to measure the temperature or monitor the degradation of components in the apparatus is provided. The ion implant apparatus may include a platen configured to move in a first direction, a mask frame to hold one or more masks disposed on the platen, a first optical sensor configured to project an optical beam to a second optical sensor, and a measurement bar disposed on the mask frame, the measurement bar raised above the surface of the mask frame to interrupt the optical beam when the platen moves in the first direction.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/736,624 filed Dec. 13, 2012, entitled “Magnetically Manipulating Masks for Ion Implantation.” 
     
    
     FIELD 
       [0002]    The present embodiments relate to ion implanters and particularly to securing mask frames for use in ion implantation. 
       BACKGROUND 
       [0003]    Ion implanters are widely used in electronic device fabrication, including semiconductor manufacturing to control device properties. In a typical ion implanter, ions generated from an ion source are directed as an ion beam through a series of beam-line components that may include one or more analyzing magnets and a plurality of electrodes that provide electric fields to tailor the ion beam properties. The analyzing magnets select desired ion species, filter out contaminant species and ions having undesirable energies, and adjust ion beam quality at a target wafer. Suitably shaped electrodes may modify the energy and the shape of an ion beam. 
         [0004]    Additionally, masks may be placed over the target wafer to block areas of the target wafer from being exposed to the ion beam. As will be appreciated, mask alignment is critical to correct implantation. More specifically, properly aligning the mask is required to ensure that the ions are implanted at desired locations in the target wafer. In some ion implanters, a mask frame is used to support or hold one or more masks. This mask frame is positioned over the target wafer in the path of the ion beam to selectively block portions of the target wafer from being exposed to the ion beam. Accordingly, placing the mask frame over the target wafer and aligning the masks to the target wafer are used to correctly implant ions in the target wafer. As will be appreciated, the mask frame may be placed one or more times while the target wafer is undergoing processing in an ion implant apparatus. Each time, the masks may need to be aligned to the target wafer. As such, mask frames that can be repeatedly placed and aligned in an efficient and reliable manner are needed. Such mask frames may improve manufacturing throughput and efficiency. 
       SUMMARY 
       [0005]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter. 
         [0006]    In one embodiment, a mask frame to hold one or more masks is provided. The mask frame may include a mask connected to the mask frame and a ferrous slug disposed in the mask frame, the ferrous slug configured to allow the mask frame to be retained by a transfer mechanism using a magnet. 
         [0007]    In one embodiment, an apparatus for placing a mask frame on a carrier may be provided. The apparatus may include a mask frame, a ferrous slug disposed in the mask frame, and a transfer mechanism including a magnet, the magnet configured to clamp to the ferrous slug to retain the mask frame against the transfer mechanism, the transfer mechanism configured to move the mask frame while the mask is retained against the transfer mechanism. 
         [0008]    In one embodiment, a method of placing a mask frame on a carrier is provided. The method may include moving a mask frame including a ferrous slug proximate to a carrier, the mask frame retained by a transfer mechanism, the transfer mechanism including a magnet clamped to the ferrous slug, placing the mask frame on the carrier, deactivating the magnet to release the ferrous slug, and moving the transfer mechanism away from the mask frame. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIGS. 1A-1C  depict block diagrams of a system for placing a mask frame in an ion implantation apparatus; 
           [0010]      FIGS. 2-3  depict perspective views of a mask frame and transfer mechanism; 
           [0011]      FIG. 4-5  depict block diagrams of mask frame and carrier; and 
           [0012]      FIG. 6  depicts a flow diagram of a method of placing and aligning a mask frame in an ion implant apparatus, all arranged according to at least one embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The present embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some embodiments are shown. The subject matter of the present disclosure, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. In the drawings, like numbers refer to like elements throughout. 
         [0014]    Various embodiments described herein provide apparatuses and methods to place and align masks over a workpiece (e.g., wafer, target substrate, or the like) in an ion implant apparatus. In particular, a mask frame having magnets may be rapidly transferred from a transfer mechanism to a carrier and individual masks in the mask frame aligned to workpieces using an alignment pin mechanism. The disclosed mark transfer and alignment apparatuses may be implemented in an ion implant apparatus. For example, the mask transfer and alignment apparatuses may be implemented to repeatedly place a mask frame on a carrier, where the mask frame includes one or more masks and the carrier supports one or more workpieces. The masks may be aligned to the workpieces while the mask frame is placed on the carrier. 
         [0015]      FIGS. 1A-1C  illustrate block diagrams of a system  1000  for placing a mask frame  100  in an ion implantation apparatus. In particular, the system  1000  depicts transferring the mask frame  100  between a transfer mechanism  200 , and a carrier  300 . The mask frame  100 , the transfer mechanism  200 , and the carrier  300  may be included in an ion implant apparatus. More specifically, the mask frame  100 , the transfer mechanism  200 , and the carrier  300  may be included in a processes chamber of an ion implant apparatus. In general,  FIGS. 1A-1C  illustrate transferring the mask frame  100  from the transfer mechanism  200  to the carrier  300 .  FIG. 1A  illustrates the mask frame  100  attached to the transfer mechanism  200 ,  FIG. 1B  illustrates the mask frame  100  being transferred from the transfer mechanism  200  to the carrier  300  using magnets (described in greater detail below) and  FIG. 1C  illustrates the mask frame  100  attached to the carrier  300 . 
         [0016]    Turning more specifically to  FIG. 1A , the mask frame  100  is shown attached to the transfer mechanism  200 . The transfer mechanism  200  may be configured to move the mask frame  100  in multiple dimensions in order to place the mask frame  100  on the carrier  300 . The transfer mechanism  200  may be operably coupled to an actuator (not shown) to manipulate the transfer mechanism  200  and place the mask frame  100  on the carrier  300 . Additionally, as will be detailed below, the mask frame  100  may be retrieved from the carrier  300  by the transfer mechanism  200 . With some examples, the actuator may be a robotic arm or other device configured to move the transfer mechanism  200  within a process chamber of an ion implantation apparatus. 
         [0017]    The transfer mechanism  200  may move the mask frame  100  to be proximate to the carrier  300 . More specifically, the transfer mechanism  200  may move the mask frame  100  in directions  10 ,  20 , and/or  30  to be proximate to the carrier  300 . In some examples, the directions  10 ,  20 , and  30  may correspond to the x, y, and z directions, respectively, of an ion implant apparatus. More specifically, an ion implant apparatus may be configured to project an ion beam in the direction  30  towards the carrier  300 . The carrier  300  may be configured to support workpieces to be implanted during an ion implant process. The transfer mechanism  200  may place the mask frame  100  on the carrier  300  in order to “mask off” or block portions of the workpieces from being exposed to the ion beam as the ion beam is projected in the direction  30  towards the carrier  300 . 
         [0018]    As stated, the mask frame  100  may be magnetically transferred between the transfer mechanism  200  and the carrier  300 . As such, the transfer mechanism  200  may include magnets  210  to retain the mask frame  100  so the mask frame  100  may be positioned on the carrier  300 . It is to be appreciated, that the carrier  300  may include a variety of mechanism to retain the mask frame  100 . In some examples (e.g., as described in conjunction with  FIGS. 1A-1C ) the carrier  300  may also include magnets  310  to retain the mask frame  100  once placed by the transfer mechanism  200 . In some examples (not shown) the carrier  300  may include mechanical retaining mechanisms (e.g., hooks, pins, clamps, springs, or the like) to retain the mask frame  100  once placed by the transfer mechanism  200 . 
         [0019]    In order to be retained by the magnets  210  and/or the magnets  310 , the mask frame includes ferrous slugs  110 . In some examples, the ferrous slugs  110  may be comprised of steel, a steel alloy, or another material that includes Iron (“Fe”). With some examples, the ferrous slugs  110  may be comprised of 1018 steel. The magnets  210  and  310  may be configured to clamp to the ferrous slugs  110 . In some examples, the magnets  210  and  310  may be configured to clamp to the ferrous slugs  110  and minimize a magnetic field (not shown) extending from the ferrous slugs  110 . 
         [0020]    With some examples, the magnets  210  and  310  may be fabricated of AlNiCo and SmCo or AlNiCo and Nd. In some examples, magnets  210  and  310  AlNiCo and Nd may be used with lower operating temperatures, such as operating temperatures less than approximately 140° C. With some examples, the magnets  210  and/or  310  may be approximately 1 to 4 inches in diameter and height and may be approximately 8 to 12 inches in length. In one particular embodiment, the magnets  210  may be 2 inches by 2 inches by 9.5 inches in dimension and generate over 120 lbs. of clamping force at zero air gap and approximately 35 lbs. of clamping force at an approximate 0.03 inch air gap. 
         [0021]    In some examples, magnets  210  may be different shapes, types, and/or strengths than the magnets  310 . For example, the magnets  310  are barrel-shaped with a 0.75 inch diameter and 1 inch height, which produce approximately 10 lbs. of clamping force. Furthermore, in some examples, there may be more magnets  310  than magnets  210 . In some examples, the total clamping force of the magnets  210  may be greater than or equal to the total clamping force of the magnets  310 . 
         [0022]    In some examples, the magnets  210  and/or  310  may be switchable (e.g., electronically controlled) to turn on and off in order to transfer the mask frame  100  between the transfer mechanism  200  and the carrier  300 . For example,  FIG. 1A  shows the magnets  210  on and clamping the ferrous slugs  110  so that the mask frame  100  is attached to the transfer mechanism  200 . The transfer mechanism  200  may move the mask frame  100  to be adjacent to the carrier  300 . 
         [0023]    Turning more specifically to  FIG. 1B , the mask frame  100  is shown adjacent to the carrier  300 . More specifically, the transfer mechanism  200  has moved the mask frame  100  in the direction  30  to be placed on the carrier  300 . The mask frame  100  can then be handed off from the transfer mechanism  200  to the carrier  300  by disengaging the magnets  210 , thereby releasing the ferrous slugs  110  and the mask frame  100 . Additionally, the magnets  310  may be engaged to clamp the ferrous slugs  110 . As such, the mask frame  100  may be passed between the transfer mechanism  200  and the carrier  300 . In some examples, the magnets  210  may be deactivated (e.g., turned off, powered down, or the like) after the mask frame  100  has partially and/or fully aligned to the carrier  300  (refer to  FIGS. 4-5 .) In some examples, the magnets  210  may be deactivated after the masks in the mask frame  100  have partially and/or fully aligned to the workpieces supported by the carrier  300  (again, refer to  FIGS. 4-5 .) 
         [0024]    In some examples, the magnets  210  may be configured to change states from on to off in approximately 0.3 seconds. Furthermore, The ferrous slugs  110  may be configured to release any residual charge stored within them from being clamped by the magnets  210 , which may aid in the release of the ferrous slugs  110  from the magnets  210 . In some examples, the magnets  210  may be permanently activated or deactivated (i.e., on or off). As such, in the event of a power failure, the mask frame  100  may remain held or clamped to the carrier  300  or transfer mechanism  200 . 
         [0025]    Once the magnets  210  are turned off and the mask frame  100  is transferred to the carrier  300 , the transfer mechanism  200  may be moved away from the mask frame  100 . Said differently, the transfer mechanism  200  may be moved out of the path of an ion beam so that any workpieces supported by the carrier may be processed in an ion implantation process. For example, the transfer mechanism  200  may be backed away from the mask frame  100  (e.g., in the direction  30 ) and then moved in the direction  10  and/or  20  so that an ion beam projected in the direction  30  towards the carrier  300  will not strike the transfer mechanism  200 . More specifically, during an ion implant process, as an ion beam is projected in the direction  30 , the ion beam may be scanned across the mask frame and carrier (e.g., in the direction  10 ) while the carrier is translated (e.g., in the direction  20  by a platen and drive assembly, or the like) to expose portions of the workpiece to the ion beam. 
         [0026]    Turning more specifically to  FIG. 1C , the mask frame  100  is shown attached to the carrier  300 . The transfer mechanism  200  is shown backed away from the mask frame  100 . As described, the mask frame  100  may be transferred between the transfer mechanism  200  and the carrier  300 . In some examples, the mask frame  100  may also be retrieved from the carrier  300 , by for example, reversing the process described in conjunction with  FIGS. 1A-1C . More specifically, the transfer mechanism  200  may be moved adjacent to the mask frame  100 , the carrier  300  may release the mask frame  100  (e.g., by deactivating magnets  310 , the transfer mechanism  200  may attach to the mask frame  100  (e.g., by activating magnets  210  to clamp to ferrous slugs  110 ) and the mask frame  100  may be removed from the carrier  300 . 
         [0027]      FIGS. 2-3  illustrate perspective views of the transfer mechanism  200  and the mask frame  100 . In general,  FIG. 2  depicts the mask frame  100  attached to the transfer mechanism  200  while  FIG. 3  depicts the mask frame  100  apart from the transfer mechanism  200 . Turning more specifically to  FIG. 2 , the mask frame  100  is depicted having multiple masks  120 - 1  to  120 -N positioned on the mask frame  100 . As used herein, a single but unspecific mask may be referred to as mask  120 . Furthermore, the masks  120 - 1  to  120 -N collectively may be referred to as masks  120 . Additionally, it is to be appreciated, that the number of masks  120  are shown at a quantity to facilitate understanding and is not intended to be limiting. As such, with various examples, more or less masks  120  than depicted may be provided. 
         [0028]    In some examples, the masks  120  are disposed on the mask frame  100 . With some examples, the masks  120  are disposed in the mask frame  100 . Furthermore, each of the masks  120  includes at least one aperture  122 . For example, ones of the apertures  122  of the mask  110 - 1  are denoted with reference designators in  FIG. 2 . It is to be appreciated that not all apertures  122  are denoted with referenced designators in  FIG. 2  for clarity of presentation. Additionally, it is to be appreciated, that the number of apertures  122  are shown at a quantity to facilitate understanding and is not intended to be limiting. Furthermore, it is to be appreciated that the shape of the apertures  122  may vary from implementation to implementations. For example, the apertures  122  may have different shapes, different sizes, different positioning, or the like. Additionally, with some examples, the apertures  122  of one mask  120  may be different than the apertures  122  of another mask  120 . Furthermore, it is important to note that the mask frame  100 , the masks  120 , the apertures  122 , and the transfer mechanism  200  are not drawn to scale. 
         [0029]    As described above with respect to  FIGS. 1A-1C , the mask frame  100  may be transferred between the transfer mechanism  200  and the carrier  300  magnetically. More specifically, the magnets  210  and  310  may be used to clamp the ferrous slugs  110 .  FIG. 2  depicts the mask frame  100  including a first ferrous slug  110 - 1  and a second ferrous slug  110 - 2 . As depicted, the first ferrous slug  110 - 1  and the second ferrous slug  110 - 2  are disposed on opposite sides of the mask frame  100 . In some examples, however, the first ferrous slug  110 - 1  and the second ferrous slug  110 - 2  may be disposed on a top and bottom of the mask frame  100 . In some examples, more than two ferrous slugs  110  may be provided. It is important to note, however, the positioning of the ferrous slugs  110  may be chosen to provide a secure attachment of the mask frame  100  to the transfer mechanism  200  and to the carrier  300 . 
         [0030]    With some examples, the first ferrous slug  110 - 1  and the second ferrous slug  110 - 2  may be positioned within the mask frame  100 . More specifically, the mask frame  100  may be two-part (not shown for clarity) and cavities may be included in the mask frame  100  so the first ferrous slug  110 - 1  and the second ferrous slug  110 - 2  can be fastened in the mask frame  100 . Furthermore, the mask frame  100  may include apertures (not shown) to expose portions of the first ferrous slug  110 - 1  and the second ferrous slug  110 - 2 . Said differently apertures may be provided to expose portions of the ferrous slugs  110  so that the magnets  210  and/or  310  may clamp the ferrous slugs  110 . In some examples, the mask frame  100  may include more than two ferrous slugs  110 . Furthermore, the ferrous slugs  110  may be formed from multiple parts. 
         [0031]    Turning more specifically to  FIG. 3 , the mask frame is depicted apart from the transfer mechanism  200 . As can be seen, the transfer mechanism  200  including magnets  210  is depicted. More specifically, the transfer mechanism  200  is depicted including magnets  210 - 1  to  210 - 4 . It is to be appreciated, that the number of magnets  210  is shown at a quantity to facilitate understanding. In some examples, more or less than 4 magnets  210  may be provided in the transfer mechanism  200 . The transfer mechanism  200  is further shown including a cavity  220 . The cavity  220  may be positioned such that when the mask frame  100  is attached to the transfer mechanism  200 , the masks  120  may not be touched by the transfer mechanism  200 . In some examples, the transfer mechanism  200  may be a hollow frame or may be formed from independent arms having the magnets  210  embedded therein. 
         [0032]      FIGS. 4-5  illustrate cross-sectional views of the mask frame  100  and the carrier  300 . In general,  FIGS. 4-5  depict the mask frame  100  attached to the carrier  300  and further depict alignment mechanisms for aligning a mask  120  to a workpiece  320 . As described above, the carrier  300  may be configured to support one or more workpieces  320 . The carrier  300  and the workpieces  320  may be disposed on a platen  400  in a process chamber of an ion implant apparatus. It is to be appreciated, that  FIGS. 4-5  depict a single mask  120  and a single workpiece  320 . However, in some implementations, the mask frame  100  may include a number of masks  120  while the carrier  300  (and/or the platen  400 ) supports a number of workpieces (e.g., multiple workpieces  320 , or the like.) Examples are not limited in this context. 
         [0033]    In order to control the areas of the workpiece  320  that are implanted with ions during an ion implantation process, the mask  120  is provided with the apertures  122  to allow selected areas (e.g., those visible or exposed through the apertures  122 ) to be exposed to an ion beam. As described above, in order to ensure that the aperture  122  expose the desired areas of the workpiece  320 , the mask  120  is aligned with the workpiece  320 . In various examples, the mask  120  may be aligned with the workpiece  320  as part of transferring the mask frame  100  from the transfer mechanism  200  to the carrier  300 .  FIGS. 4-5  depict alignment apparatuses that may be used to align the mask  120  to the workpiece  320  while the mask frame  100  is placed on the carrier  300 . 
         [0034]    Turning more specifically to  FIG. 4 , a cross sectional view of an alignment apparatus including alignment bolts  330  is illustrated. As depicted, the carrier  300  and/or the platen  400  are supporting the workpiece  320 . The carrier  300  includes workpiece pins  340  or other mechanisms that press or push the workpiece  320 . In some examples, the workpiece pins  340  may be operably connected to the alignment bolts, to push on or press the workpiece as the alignment bolts  330  are pressed on. Said differently, as the alignment bolts  330  are pressed on (e.g., in the direction  30 ) the workpiece pins  340  will exert pressure on the workpiece  320  to center the workpiece  320  between the alignment bolts  330 . With some examples, the workpiece pins  340  may be operably connected to alignment pins (refer to  FIG. 5 ) that operate to center the workpiece  320  below the mask  120 . 
         [0035]    Furthermore, the alignment bolts  330  are used to center the mask  120  over the workpiece  320 . In some examples, the edges of the mask  120  may be configured to slide against the alignment bolts  330  to center the mask  120  over the workpiece  320 . In some examples, the mask  120  may include an alignment hole (not shown) in which the alignment bolts  330  fit. In further examples, the alignment hole may be larger than the alignment bolt  330  to provide a loose-fit around the alignment bolt  330  to enable the mask  120  to move slightly. 
         [0036]    In some examples, the alignment bolt  330  may have multiple diameters (e.g., as illustrated in  FIG. 4 .) In some examples, the alignment bolts  330  may be tapered, cone shaped, or have other shapes that facilitate receiving the mask  120 . In some examples, a spring  350  and washer  360  are disposed around the alignment bolt  320 . With some examples, the spring  350  and the washer  360  may be disposed around the alignment bolt  320  between the mask  120  and the mask frame  100  (e.g., as depicted in  FIG. 4 .) In some examples, the spring  350  and the washer  360  may be disposed around the alignment bolt  320  between the mask  120  and the carrier  300 . 
         [0037]    Accordingly, during operation, as the mask frame  100  is placed on the carrier  300 , the mask  120  will be centered between the alignment bolts  330 . The weight of the mask frame  100  will rest on the alignment bolts  330 , which centered the workpiece  320  between the alignment bolts  330 . As such, both the mask  120  and the workpiece  320  may be centered between the alignment bolts  330 . 
         [0038]    Turning more specifically to  FIG. 5 , another cross sectional view of the alignment apparatus depicted in  FIG. 4  is shown. As can be seen, alignment pins  370  are depicted extending through the carrier  300  and pressing against the pin  340 . The alignment pins  370  may be operably connected to the workpiece pins  340  to exert pressure on the workpiece pins  340 , which further exert pressure on the workpiece  320 . The alignment pins  370  may also extend into cavities  400  of the mask  120 . During operation, as the alignment pins  370  are centered in the cavity  400  of the mask  120 , the mask  120  may be aligned to the workpiece  320 . Furthermore, the alignment pins  370  also enable the workpiece  320  to be aligned in the carrier  300 . Said differently, the alignment bolts  330 , the alignment pins  370 , and the workpiece pins  340  may operate together to center the workpiece  320  over the carrier and the mask  120  over the workpiece  320 . 
         [0039]    Accordingly,  FIGS. 4-5  depicts an alignment apparatus that may be used to align the mask  120  to the workpiece  320  as the mask frame  100  is placed on the carrier  300 . In some examples, an array of alignment apparatuses as described in  FIGS. 4-5  may be provided to align the mask  120  of the mask frame  100  with the workpieces  320  supported by the carrier  300 . 
         [0040]      FIG. 6  illustrates a flow chart for a method  600  that may be implemented in an ion implanter to place a mask frame on a carrier and further to align a mask in the mask frame with a workpiece supported by the carrier. For example, the method  600  may be implemented to place the mask frame  100  on the carrier  300  and align the masks  120  with the workpieces  320 . Although the method  600  is described with reference to the transport mechanism  200 , the mask frame  100 , and the carrier  300  of  FIGS. 1A-1C , examples are not limited in this context. 
         [0041]    The method  600  may begin at block  610 . At block  610 , move a mask frame to be proximate to a carrier, the mask frame clamped to the carrier by magnets in a transfer mechanism and ferrous slugs in the mask frame, the transfer mechanism  200  may move the mask frame  100  to be proximate to the carrier  300 . During such movement, the mask frame  100  may be attached to the transfer mechanism  200  by the magnets  210  and the ferrous slugs  110 . More specifically, the magnets  210  may clamp to the ferrous slugs  110  to retain the mask frame  100  against the transfer mechanism  200 . 
         [0042]    Continuing to block  620 , place the mask frame on the carrier, the transfer mechanism  200  may place the mask frame  100  on the carrier  300 . Continuing to block  630 , disengage the magnets to release the ferrous slugs, the magnets  210  may be deactivated to release the ferrous slugs  110 . Continuing to block  640 , move the transfer mechanism away from the mask frame  100  leaving the mask frame  100  on the carrier  300 , the transfer mechanism  200  may be moved away from the mask frame  100  leaving the mask frame  100  on the carrier  300 . 
         [0043]    Thus, a mask frame may be aligned to a carrier and individual masks aligned to workpieces using the apparatuses and methods described above. More specifically, the mask frame  100  may be aligned to the carrier  300  and the masks  120  aligned to the workpieces  320 . In various examples, the masks  120  may be aligned to within approximately 20 μm of a desired location. 
         [0044]    The present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are in the tended to fall within the scope of the present disclosure. Furthermore, although the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Thus, the claims set forth below should be construed in view of the full breadth and spirit of the present disclosure as described herein.