Abstract:
A target supply unit may include: a reservoir for storing a target material; a heater provided inside the reservoir for heating the target material stored in the reservoir; a heater power supply for supplying current to the heater; and a target outlet for outputting the target material stored inside the reservoir.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application No. 2011-060903 filed Mar. 18, 2011. 
     BACKGROUND 
     1. Technical Field 
     This disclosure relates to a target supply unit. 
     2. Related Art 
     In recent years, semiconductor production processes have become capable of producing semiconductor devices with increasingly fine feature sizes, as photolithography has been making rapid progress toward finer fabrication. In the next generation of semiconductor production processes, microfabrication with feature sizes at 60 nm to 45 nm, and further, microfabrication with feature sizes of 32 nm or less will be required. In order to meet the demand for microfabrication with feature sizes of 32 nm or less, for example, an exposure apparatus is needed in which a system for generating extreme ultraviolet (EUV) light at a wavelength of approximately 13 nm is combined with a reduced projection reflective optical system. 
     Three kinds of systems for generating EUV light are known in general, which include a Laser Produced Plasma (LPP) type system in which plasma is generated by irradiating a target material with a laser beam, a Discharge Produced Plasma (DPP) type system in which plasma is generated by electric discharge, and a Synchrotron Radiation (SR) type system in which orbital radiation is used. 
     SUMMARY 
     A target supply unit according to one aspect of this disclosure may include: a reservoir for storing a target material; a heater provided inside the reservoir for heating the target material stored in the reservoir; a heater power supply for supplying a current to the heater; and a target outlet for outputting the target material stored inside the reservoir. 
     A target supply unit according to another aspect of this disclosure may include: a reservoir for storing a target material; an infrared heater provided outside the reservoir for heating the target material stored in the reservoir by radiated heat; a heater power supply for supplying a current to the infrared heater; and a target outlet for outputting the target material stored inside the reservoir. 
     A target supply unit according to yet another aspect of this disclosure may include: a reservoir for storing a target material; an induction heater provided outside the reservoir for heating the target material stored in the reservoir by induction heating; a high-frequency power supply for supplying a high-frequency current to the induction heater; and a target outlet for outputting the target material stored inside the reservoir. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of this disclosure will now be described with reference to the accompanying drawings. 
         FIG. 1  schematically shows the configuration of an LPP-type EUV light generation apparatus. 
         FIG. 2  is a partial sectional view of an EUV light generation apparatus in which a target supply unit according to a first embodiment is employed. 
         FIG. 3  is a partial sectional view of the target supply unit according to the first embodiment. 
         FIG. 4  is a partial sectional view of a target supply unit according to a second embodiment. 
         FIG. 5  is a partial sectional view of a target supply unit according to a third embodiment. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereinafter, embodiments of this disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below are merely illustrative in nature and do not limit the scope of this disclosure. Further, the configurations and operations described in connection with each embodiment are not necessarily essential in implementation of the configurations and operations in this disclosure. Like elements are referenced by like reference numerals or symbols, and duplicate descriptions thereof will be omitted herein. 
     TABLE OF CONTENTS 
     
         
         1. Overview 
         2. General Description of EUV Light Generation Apparatus
       2.1 Configuration   2.2 Operation   
     
         3. Embodiments of Target Supply Unit
       3.1 First Embodiment
           3.1.1 Configuration   3.1.2 Operation   
           3.2 Second Embodiment   3.3 Third Embodiment
 
1. Overview
   
     
       
    
     In each embodiment of this disclosure, to melt a metal for use as a target material in an EUV light generation apparatus and to retain the target material temperature at or above the melting point, the target material inside a reservoir may be directly heated. When the target material is directly heated, it may be possible to heat and melt the target material efficiently, as compared to a case where the reservoir is heated to heat the target material in the reservoir. It may also be possible to efficiently retain the target material temperature at or above the melting point. 
     2. General Description of EUV Light Generation Apparatus 
     2.1 Configuration 
       FIG. 1  schematically illustrates the configuration of an exemplary LPP type EUV light generation system. An EUV light generation apparatus  1  may be used with at least one laser apparatus  3 . In this application, a system including the EUV light generation apparatus  1  and the laser apparatus  3  may be referred to as an EUV light generation system  11 . As illustrated in  FIG. 1  and described in detail below, the EUV light generation apparatus  1  may include a chamber  2 , a target supply unit (droplet generator  26 , for example), and so forth. The chamber  2  may be airtightly sealed. The target supply unit may be mounted to the chamber  2  so as to pass through the wall of the chamber  2 , for example. A target material to be supplied by the target supply unit may include, but is not limited to, tin, terbium, gadolinium, lithium, xenon, or any combination, alloy, or mixture thereof. 
     The chamber  2  may have at least one through-hole formed in the wall thereof. The through-hole may be covered with a window  21 , and a pulsed laser beam  32  may travel through the window  21  into the chamber  2 . An EUV collector mirror  23  having a spheroidal reflective surface may be disposed inside the chamber  2 , for example. The EUV collector mirror  23  may have first and second foci. The EUV collector mirror  23  may have a multi-layered reflective film formed on a surface thereof, and the reflective film can include molybdenum and silicon that is laminated in alternate layers, for example. The EUV collector mirror  23  may preferably be disposed such that the first focus thereof lies in a plasma generation region  25  and the second focus thereof lies in an intermediate focus (IF) region  292  defined by the specification of an exposure apparatus  6 . The EUV collector mirror  23  may have a through-hole  24  formed at the center thereof, and a pulsed laser beam  33  may travel through the through-hole  24 . 
     The EUV light generation system  11  may include an EUV light generation controller  5 . Further, the EUV light generation apparatus  1  may include a target sensor  4 . The target sensor  4  may have an imaging function and may detect at least one of the presence, trajectory, and position of a target. 
     Further, the EUV light generation apparatus  1  may include a connection part  29  for allowing the interior of the chamber  2  and the interior of the exposure apparatus  6  to be in communication with each other. A wall  291  having an aperture may be disposed inside the connection part  29 . The wall  291  may be disposed such that the second focus of the EUV collector mirror  23  lies in the aperture formed in the wall  291 . 
     Further, the EUV light generation system  1  may include a laser beam direction control unit  34 , a laser beam focusing mirror  22 , and a target collection unit  28  for collecting a target  27 . The laser beam direction control unit  34  may include an optical element for defining the direction in which the laser beam travels and an actuator for adjusting the position and the orientation (or posture) of the optical element. 
     2.2 Operation 
     With reference to  FIG. 1 , a pulsed laser beam  31  outputted from the laser apparatus  3  may pass through the laser beam direction control unit  34 , and may be outputted from the laser beam direction control unit  34  as a pulsed laser beam  32  after having its direction optionally adjusted. The pulsed laser beam  32  may travel through the window  21  and enter the chamber  2 . The pulsed laser beam  32  may travel inside the chamber  2  along at least one beam path from the laser apparatus  3 , be reflected by the laser beam focusing mirror  22 , and strike at least one target  27  as a pulsed laser beam  33 . 
     The droplet generator  26  may output the targets  27  toward the plasma generation region  25  inside the chamber  2 . The target  27  may be irradiated by at least one pulse of the pulsed laser beam  33 . The target  27 , which has been irradiated by the pulsed laser beam  33 , may be turned into plasma, and rays of light including EUV light  251  may be emitted from the plasma. The EUV light  251  may be reflected selectively by the EUV collector mirror  23 . EUV light  252  reflected by the EUV collector mirror  23  may travel through the intermediate focus region  292  and be outputted to the exposure apparatus  6 . The target  27  may be irradiated by multiple pulses included in the pulsed laser beam  33 . 
     The EUV light generation controller  5  may integrally control the EUV light generation system  11 . The EUV light generation controller  5  may be configured to process image data of the droplet  27  captured by the target sensor  4 . Further, the EUV light generation controller  5  may control at least one of the timing at which the target  27  is outputted and the direction into which the target  27  is outputted (e.g., the timing with which and/or direction in which the target is output from droplet generator  26 ). Furthermore, the EUV light generation controller  5  may control at least one of the timing with which the laser apparatus  3  oscillates (e.g., by controlling laser apparatus  3 ), the direction in which the pulsed laser beam  31  travels (e.g., by controlling laser beam direction control unit  34 ), and the position at which the pulsed laser beam  33  is focused (e.g., by controlling laser apparatus  3 , laser beam direction control unit  34 , or the like), for example. The various controls mentioned above are merely examples, and other controls may be added as necessary. 
     3. Embodiments of Target Supply Unit 
     3.1 First Embodiment 
     3.1.1 Configuration 
       FIG. 2  is a partial sectional view of an EUV light generation apparatus in which a target supply unit according to a first embodiment is employed. As shown in  FIG. 2 , a laser beam focusing optical system  22   a , the EUV collector mirror  23 , the target collection unit  28 , an EUV collector mirror holder  41 , plates  42  and  43 , a laser beam dump  44 , and a laser beam dump support member  45  may be provided inside the chamber  2 . 
     The plate  42  may be provided to the chamber  2 , and the plate  43  may be provided to the plate  42 . The EUV collector mirror  23  may be provided to the plate  42  via the EUV collector mirror holder  41 . 
     The laser beam focusing optical system  22   a  may include an off-axis paraboloidal mirror  221 , a plane mirror  222 , and holders therefor. The off-axis paraboloidal mirror  221  and the plane mirror  222  may be provided to the plate  43  via their respective holders so that a pulse laser beam is focused in the plasma generation region  25 . The laser beam dump  44  may be provided to the chamber  2  via the laser beam dump support member  45  and may be disposed in the beam path of a pulse laser beam. The target collection unit  28  may be disposed in the trajectory of the target  27  and at a position lower than the plasma generation region  25  in the droplet traveling direction (toward the bottom of the figure). 
     The chamber  2  may be provided with the window  21  and the droplet generator (target supply unit)  26 . A detailed description of the droplet generator  26  will be given later. A heated and molten metal or the like may be used as a target material. In the following embodiments, tin (Sn), which has a melting point of 232° C., is used as an example. 
     A beam delivery unit  34   a  and the EUV light generation controller  5  may be provided outside the chamber  2 . The beam delivery unit  34   a  may include high-reflection mirrors  341  and  342 , holders therefor, and a housing. The EUV light generation controller  5  may include an EUV light generation control device  51 , a droplet control device  52 , a pressure regulator  53 , and a pulse voltage generator  55 . 
     Next, the configuration of the droplet generator  26  will be described in more detail.  FIG. 3  is a partial sectional view of the target supply unit according to the first embodiment. As shown in  FIG. 3 , the droplet generator  26  may include a reservoir  61 , a nozzle  62 , an electrode  63 , a heater  64   a , an electrical insulating member  65 , and a pull-out electrode  66 . The reservoir  61  and the nozzle  62  may be formed integrally or separately. The droplet generator  26  may be configured to generate the target  27  on demand. The target supply unit is not limited to the droplet generator  26  which supplies the target material in the form of droplet. The target supply unit may be configured to output a continuous jet of the liquid target material. 
     The reservoir  61  may be formed of an electrically non-conductive material, such as synthetic quartz (SiO 2 ) or alumina (Al 2 O 3 ). Alternatively, the reservoir  61  may be formed of an electrically conductive material, such as molybdenum (Mo), or of a semiconductor material, such as silicon carbide (SiC). Similarly, the nozzle  62  may be formed of an electrically non-conductive material, such as synthetic quartz or alumina, an electrically conductive material, such as molybdenum, or a semiconductor material, such as silicon carbide. The reservoir  61  may store the target material, such as tin, as mentioned above. 
     The heater  64   a , together with the target material, may be contained in the reservoir  61 . The heater  64   a  may include a resistive element that generates Joule heat by a current. The target material may be heated by the heater  64   a  to thereby be molten, and the molten state of the target material may then be retained in the reservoir  61 . The droplet generator  26  may further include a temperature sensor  72   a  for detecting the temperature of the target material in the reservoir  61 . The heater  64   a  and temperature sensor  72   a  may be coated with a material having low reactivity with the target material. Such a material may be silicon carbide, for example. 
     A flexible heater  64   b  and a temperature sensor  72   b  may further be provided in the vicinity of the nozzle  62  of the droplet generator  26 . The flexible heater  64   b  and the temperature sensor  72   b  may be provided outside the reservoir  61 . The flexible heater  64   b  may preferably be capable of fitting the shape of the reservoir in the vicinity of the nozzle  62 . In place of the flexible heater  64   b , many small heaters may be disposed so as to fit the shape of the reservoir  61  in the vicinity of the nozzle  62 . Alternatively, the reservoir  61  in the vicinity of the nozzle  62  may be given a shape which fit, for example, an off-the-shelf heater. 
     The nozzle  62  has a through-hole (orifice) formed therein for outputting the target  27 . The target  27  may be output toward the plasma generation region  25  in the chamber  2  through the nozzle  62  (see also  FIG. 2 ). 
     The electrical insulating member  65  that holds the pull-out electrode  66  may be attached to the nozzle  62 . The electrical insulating member  65  provides electrical insulation between the nozzle  62  and the pull-out electrode  66 . The pull-out electrode  66  may be disposed so as to face an outlet-side surface of the nozzle  62  in order to allow the electrostatic force to act on the liquid target material through the orifice formed in the nozzle  62 . The pull-out electrode  66  has a through-hole  67  formed, for example, at the center thereof to allow the target  27  to pass therethrough. 
     The pressure regulator  53  may regulate the pressure of an inert gas supplied from an inert gas cylinder (not shown) as necessary, to push the liquid target material to the leading end of the nozzle  62 . The droplet control device  52  may control the pressure regulator  53  and the pulse voltage generator  55  so that the target  27  is generated when receiving an instruction from the EUV light generation control device  51 . 
     A wire connected to one output terminal of the pulse voltage generator  55  is connected to the electrode  63  that is in contact with the liquid target material. A wire connected to the other output terminal of the pulse voltage generator  55  is connected to the pull-out electrode  66 . Under the control of the droplet control device  52 , the pulse voltage generator  55  generates a pulse signal for pulling out the liquid target material. 
     For example, the pulse voltage generator  55  may generate a pulse signal that varies from a reference potential V 2  (0 V, for example) to a predetermined potential V 1  that is different from the reference potential. The pulse voltage generator  55  may apply this pulse signal to the liquid target material via the electrode  63 . The pulse voltage generator  55  may also apply the potential V 2  to the pull-out electrode  66 . 
     A pulse voltage (V 1 -V 2 ) is thereby applied between the liquid target material and the pull-out electrode  66 . Alternatively, when the nozzle  62  is made of metal, the pulse voltage generator  55  may apply the pulse voltage (V 1 -V 2 ) between the nozzle  62  and the pull-out electrode  66 . In this case, the wire connected to one output terminal of the pulse voltage generator  55  may be connected to the nozzle  62 , instead of to the electrode  63 . 
     The reservoir  61 , the nozzle  62 , the electrical insulating member  65 , and the pull-out electrode  66  of the droplet generator  26  may be enclosed in a shielding container that includes a cover  81  and a lid  86  attached to the cover  81 . The cover  81  has a through-hole  83  formed therein to allow the target  27  output through the nozzle  62  to pass therethrough. The cover  81  prevents a charged particle emitted from the plasma generated in the plasma generation region  25  from reaching an electrical insulator such as the electrical insulating member  65 . 
     The cover  81  includes an electrically conductive material (e.g., metal material), thereby having conductivity, and is electrically connected through a connecting member such as a wire, or directly, to an electrically conductive structural member (e.g., external wall) of the chamber  2 . The electrically conductive structural member of the chamber  2  is electrically connected to the reference potential (0 V) of the pulse voltage generator  55 , and may further be grounded. The reservoir  61  is attached to the cover  81  via the lid  86 . An electrically non-conductive material such as mullite may be used as a material of the lid  86 . 
     A wire from the pull-out electrode  66  may be connected to the pulse voltage generator  55  via a relay terminal  90   a  provided in the lid  86 . A wire from the electrode  63 , which applies a pulse signal to the liquid target material, may be connected to the pulse voltage generator  55  via a relay terminal  90   b  provided in the lid  86 . A wire from the heater  64   a  may be connected to a heater power supply  58   a  via a relay terminal  90   c  provided in the lid  86 . A wire from the temperature sensor  72   a  may be connected to a temperature controller  59   a  via a relay terminal  90   d  provided in the lid  86 . Wires from the flexible heater  64   b  and temperature sensor  72   b  may be connected to a heater power supply  58   b  and a temperature controller  59   b , respectively, via a relay terminal  90   e  provided in the lid  86 . 
     A reflector  82  for reflecting heat radiated from the reservoir  61  is formed on the inner surface of the cover  81 . The reflector  82  may be a coating of a material having high infrared ray reflectivity. A space between the cover  81  and the reservoir  61  communicates with the chamber  2  via the through-hole  83 , and is retained in a low-pressure state as in the interior of the chamber  2 . 
     3.1.2 Operation 
     Current from the heater power supplies  58   a  and  58   b  passes through the heater  64   a  and the flexible heater  64   b , respectively, by which Joule heat is generated. The Joule heat is thermally conducted to the target material, which is thereby heated. The temperature controllers  59   a  and  59   b  receive detection signals output respectively from the temperature sensors  72   a  and  72   b , and respectively control the values of currents to be supplied from the heater power supplies  58   a  and  58   b  to the heater  64   a  and the flexible heater  64   b . The temperature of the target material in the reservoir  61  is controlled to be at or above the melting point of the target material. 
     According to the first embodiment, the heater  64   a  is disposed inside the reservoir  61 , and therefore the target material is directly heated by the heater  64   a . It may thus be possible to heat the target material efficiently, as compared to a case where the target material is indirectly heated through the reservoir  61  (the reservoir  61  is heated to heat the target material therein). 
     Because the inner surface of the cover  81  is coated with the reflector  82  having high infrared ray reflectivity, the heat energy of the target material heated inside the reservoir  61  is prevented from being emitted outside the cover  81  by thermal radiation. The space between the cover  81  and the reservoir  61  is retained in a low-pressure state as in the interior of the chamber  2 . Accordingly, the heat energy of the target material in the reservoir  61  is also prevented from being emitted outside the cover  81  by thermal conduction through a gas in the space between the cover  81  and the reservoir  61 . According to the first embodiment, it may thus be possible to heat the target material efficiently, and retain the target material in the molten state. 
     Referring again to  FIG. 2 , the EUV light generation control device  51  may output a droplet output signal to the droplet control device  52 , and output a pulse laser beam output signal to the laser apparatus  3 . The droplet control device  52  outputs a droplet generation signal to the pulse voltage generator  55  according to the droplet output signal. The pulse voltage generator  55  applies a pulsing voltage to the target material in the reservoir  61  according to the droplet generation signal. The electrostatic force is thereby generated between the target material in the reservoir  61  and the pull-out electrode  66 , the target material is pulled out through the leading end of the nozzle  62 , and a charged target  27  is generated. The target  27  is charged by the potential difference (V 1 -V 2 ) applied between the electrode  63  and the pull-out electrode  66 . The target  27  is output from the droplet generator  26  toward the plasma generation region  25 . 
     The laser apparatus  3  outputs a pulse laser beam according to the pulse laser beam output signal. The pulse laser beam output from the laser apparatus  3  may be reflected off the high-reflection mirrors  341  and  342  of the beam delivery unit  34   a , and may enter the laser beam focusing optical system  22   a . The pulse laser beam having entered the laser beam focusing optical system  22   a  may be reflected off the off-axis paraboloidal mirror  221  and the plane mirror  222 , and may be focused onto the target  27  as the target  27  reaches the plasma generation region  25 . 
     In this way, the target  27  is irradiated by a pulse laser beam when the target  27  reaches the plasma generation region  25 . The target material is thereby turned into plasma, from which EUV light is emitted. The emitted EUV light may be focused in the IF region  292  by the EUV collector mirror  23 , and may enter the exposure apparatus. 
     3.2 Second Embodiment 
       FIG. 4  is a partial sectional view of a target supply unit according to a second embodiment. The second embodiment is different from the first embodiment in that an infrared heater  64   c  is disposed in a space between the reservoir  61  and cover  81 , instead of a heater being contained in the reservoir  61 . 
     The infrared heater  64   c  may comprise a halogen lamp, for example. A wire from the infrared heater  64   c  may be connected to a heater power supply  58   c  via the relay terminal  90   c  provided in the lid  86 . 
     A radiation thermometer  72   c  may be provided to the lid  86 . A high-temperature target material radiates infrared rays or visible rays having the wavelength and intensity according to the material and temperature of the target. The radiation thermometer  72   c  detects the infrared rays or the visible rays generated from the target material in the reservoir  61 , and outputs a detection signal according to the wavelength and the intensity of the rays. The radiation thermometer  72   c  may be a fiber thermometer that includes an optical fiber with an opening toward an object of which the temperature is to be measured. A wire from the radiation thermometer  72   c  may be connected to a temperature controller  59   c.    
     The infrared heater  64   c  is supplied with power from the heater power supply  58   c , and then generates infrared rays. The temperature controller  59   c  receives the detection signal output from the radiation thermometer  72   c , and controls current to be supplied from the heater power supply  58   c  to the infrared heater  64   c . The reservoir  61  may preferably be formed of a material having high transmissivity for infrared rays and low reactivity with the target material. Such a material for reservoir  61  may be quartz glass (SiO 2 ), for example. 
     According to the second embodiment, the infrared heater  64   c  is disposed in the space between the reservoir  61  and the cover  81 . It may thus be possible to heat the target material in the reservoir  61  directly by the infrared rays transmitted through the reservoir  61 . Because the infrared heater  64   c  is not in direct contact with the target material in the reservoir  61 , it may not be necessary to coat the infrared heater  64   c  with a material having low reactivity with the target material. 
     The inner surface of the cover  81  is coated with the reflector  82  having high infrared ray reflectivity, and therefore, not only the infrared rays radiated from the target material in the reservoir  61 , but also the infrared rays radiated from the infrared heater  64   c , may be reflected. It may thus be possible to heat the target material efficiently, and retain the target material in the molten state. 
     In the second embodiment, the radiation thermometer  72   c  may detect the temperature of the target material without having to be in contact with the target material. Accordingly, it may not be necessary to coat the radiation thermometer  72   c  with a material having low reactivity with the target material. 
     3.3 Third Embodiment 
       FIG. 5  is a partial sectional view of a target supply unit according to a third embodiment. The third embodiment is different from the first embodiment in that a coil  64   d  constituting an induction heater is disposed in a space between the reservoir  61  and the cover  81 , instead of a heater being contained in the reservoir  61 . 
     The coil  64   d  may comprise a conductor wound around the reservoir  61 . Wires connected to both ends of the coil  64   d  may be connected to a high-frequency heating power supply  58   d  via the relay terminal  90   c  provided in the lid  86 . The coil  64   d  is supplied with a high-frequency current from the high-frequency heating power supply  58   d . Around the coil  64   d , the high-frequency current generates a magnetic field that changes periodically. The magnetic field generates an eddy current in a metal constituting the target material, and the eddy current generates Joule heat in the target material. 
     A radiation thermometer  72   d  may be fixed to the lid  86 . The radiation thermometer  72   d  detects the infrared rays or the visible rays generated from the target material in the reservoir  61 , and outputs a detection signal according to the wavelength and the intensity of the rays. The radiation thermometer  72   d  may be a fiber thermometer that includes an optical fiber with an opening toward an object of which the temperature is to be measured. A wire from the radiation thermometer  72   d  may be connected to a temperature controller  59   d . The temperature controller  59   d  receives the detection signal output from the radiation thermometer  72   d , and controls the current value of a high-frequency current to be supplied from the high-frequency heating power supply  58   d  to the coil  64   d.    
     According to the third embodiment, the coil  64   d  of the induction heater is disposed in the space between the reservoir  61  and the cover  81 . It may thus be possible to heat the target material in the reservoir  61  directly by induction heating. Because the coil  64   d  is not in direct contact with the target material in the reservoir  61 , it may not be necessary to coat the coil  64   d  with a material having low reactivity with the target material. 
     In the third embodiment, the radiation thermometer  72   d  may detect the temperature of the target material without having to be in contact with the target material. Accordingly, it may not be necessary to coat the radiation thermometer  72   d  with a material having low reactivity with the target material. 
     The above-described embodiments and the modifications thereof are merely examples for implementing this disclosure, and this disclosure is not limited thereto. Making various modifications according to the specifications or the like is within the scope of this disclosure, and other various embodiments are possible within the scope of this disclosure. For example, the modifications illustrated for particular ones of the embodiments can be applied to other embodiments as well (including the other embodiments described herein). 
     The terms used in this specification and the appended claims should be interpreted as “non-limiting.” For example, the terms “include” and “be included” should be interpreted as “including the stated elements but not limited to the stated elements.” The term “have” should be interpreted as “having the stated elements but not limited to the stated elements.” Further, the modifier “one (a/an)” should be interpreted as at least one or “one or more.”