Abstract:
An embodiment of the present invention is a method of manufacturing a perpendicular MTJ device which includes: a first stacked structure including a pair of CoFeB layers sandwiching an MgO layer; and a second stacked structure including a multilayer, the method comprising the steps of: forming one of the first and second stacked structures on a substrate; inspecting a property of the substrate with the one of the first and second stacked structures formed thereon while exposing the substrate to the atmosphere; and forming another one of the first and second stacked structures on the substrate with the one of the first and second stacked structures formed thereon.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of International Application No. PCT/JP2015/000446, filed Feb. 2, 2015. The contents of the aforementioned applications are incorporated herein by reference in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a method of manufacturing a perpendicular magnetic tunnel junction (MTJ) device. 
       BACKGROUND ART 
       [0003]    Next-generation spin transfer torque magnetoresistive random access memories (STT-MTRAMs) use perpendicular MTJ devices, the magnetization direction of which is perpendicular to the film surface. Each of layers constituting a perpendicular MTJ device is very thin, and the properties thereof are liable to degrade when the perpendicular MTJ device is exposed to the atmosphere during the process of film formation. In the technique of Non-patent document 1, the entire process is consistently performed under vacuum in order to prevent degradation of the properties of the barrier layer and the perpendicular magnetic anisotropy layer. 
         [0004]    At the same time, it is necessary to measure both the magnetoresistance (MR) properties and the perpendicular magnetic properties for management of the process of manufacturing MTJ devices. For this reason, in the technique of Non-patent Document 1, inspection of the MR (magnetoresistance) properties and perpendicular magnetic anisotropy properties is performed for completed perpendicular MTJ devices. 
       CITATION LIST 
     Non Patent Document 
       [0005]    Non Patent Document 1: D. C. Worledge et al., Appl. Phys. Lett. 98, 022501 (2011) 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    However, with the conventional method that performs property inspections for completed perpendicular MTJ devices, in the case of trouble such as the case where desired properties are not obtained and the yield is thereby reduced, it is difficult to identify the cause of such a trouble. 
         [0007]    Accordingly, in the light of the aforementioned problem, an object of the present invention is to provide a method of manufacturing a perpendicular MTJ device which separately includes a step of inspecting the MR properties and a step of inspecting the perpendicular magnetic anisotropy properties. 
       Solution to Problem 
       [0008]    An embodiment of the present invention is a method of manufacturing a perpendicular MTJ device which includes: a first stacked structure including a pair of CoFeB layers sandwiching an MgO layer; and a second stacked structure including a multilayer, the method comprising the steps of: forming one of the first and second stacked structures on a substrate; inspecting a property of the substrate with the one of the first and second stacked structures formed thereon while exposing the substrate to an atmosphere; and forming an other one of the first and second stacked structures on the substrate with the one of the first and second stacked structures formed thereon. 
       Advantageous Effects of Invention 
       [0009]    With the method of manufacturing a perpendicular MTJ device according to the embodiment of the present invention, the management of the properties of the perpendicular MTJ device can be simplified. Specifically, the method of manufacturing a perpendicular MTJ device separately includes the step of forming the stacked structure influencing the MR properties and the step of forming the stacked structure influencing the perpendicular magnetic anisotropy properties, and separately performs the steps of inspecting the MR properties and perpendicular magnetic anisotropy properties. Accordingly, in the case of trouble such as the case where the desired properties are not obtained, it is possible to easily identify which stacked structure causes the trouble. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1A  is a schematic diagram illustrating a layer structure of a top-pinned perpendicular MTJ device. 
           [0011]      FIG. 1B  is a schematic diagram illustrating a layer structure of a bottom-pinned perpendicular MTJ device. 
           [0012]      FIG. 2A  is a schematic diagram illustrating separate film formation of the top-pinned perpendicular MTJ device. 
           [0013]      FIG. 2B  is a schematic diagram illustrating separate film formation of the top-pinned perpendicular MTJ device. 
           [0014]      FIG. 2C  is a schematic diagram illustrating separate film formation of the top-pinned perpendicular MTJ device. 
           [0015]      FIG. 2D  is a schematic diagram illustrating separate film formation of the top-pinned perpendicular MTJ device. 
           [0016]      FIG. 3A  is a schematic diagram illustrating separate film formation of the bottom-pinned perpendicular MTJ device. 
           [0017]      FIG. 3B  is a schematic diagram illustrating separate film formation of the bottom-pinned perpendicular MTJ device. 
           [0018]      FIG. 3C  is a schematic diagram illustrating separate film formation of the bottom-pinned perpendicular MTJ device. 
           [0019]      FIG. 4  is a schematic configuration diagram of a manufacturing system including a single-core sputtering apparatus. 
           [0020]      FIG. 5  is a schematic configuration diagram of a double-core sputtering apparatus. 
           [0021]      FIG. 6  is a flowchart according to a method of manufacturing a top-pinned perpendicular MTJ device. 
           [0022]      FIG. 7  is a flowchart according to a method of manufacturing a bottom-pinned perpendicular MTJ device. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0023]      FIGS. 1A and 1B  are schematic diagrams illustrating a layered structure of a perpendicular MTJ device according to a first embodiment of the present invention. The thickness of each layer illustrated in the drawings is consistently schematic and does not suggest a relative thickness of each layer of a perpendicular MTJ device actually manufactured. 
         [0024]    The perpendicular MTJ device includes a top-pinned perpendicular MTJ device  100 A ( FIG. 1A ) and a bottom-pinned perpendicular MTJ device  100 B ( FIG. 1B ). 
         [0025]    A description is given of the top-pinned perpendicular MTJ device  100 A illustrated in  FIG. 1A . The top-pinned perpendicular MTJ device  100 A includes a bottom electrode  102 , a Ta layer (a seed layer)  103 , a CoFeB layer  104  as a free layer (a magnetization free layer), a MgO layer (a tunnel barrier layer)  105 , and a CoFeB layer  106  as a reference layer (a magnetization fixed layer), which are sequentially provided on a substrate  101  made of silicon or the like. 
         [0026]    The top-pinned perpendicular MTJ device  100 A further includes a Ta layer  107 , superlattice [Co/Pt] multilayer  110 A, an Ru layer  110 C, superlattice [Co/Pt] multilayer  110 B, an Ru layer  115  (a cap layer), a Ta layer  111 , and a top electrode  112 , which are sequentially provided on the CoFeB layer  106 . The [Co/Pt] multilayers  110 A and  110 B include predetermined numbers of Co layers and Pt layers alternately stacked on each other. A Ru layer  110 C is a layer to magnetically couple the upper [Co/Pt] multilayer  110 B to the lower [Co/Pt] multilayer  110 A. 
         [0027]    The number of pairs of Co and Pt layers adjacent to each other in the [Co/Pt] multilayer  110 A is three to five, and the number of pairs of Co and Pt layers adjacent to each other in the [Co/Pt] multilayer  110 B is 8 to 15. The numbers of pairs are not limited to these values. Additionally, the [Co/Pt] multilayers  110 A and  110 B may be replaced with [Co/Pd] multilayers including Pd layers instead of the Pt layers. Moreover, the thicknesses of the Ta layer  103 , CoFeB layer  104 , MgO layer  105 , CoFeB layer  106 , and Ta layer  107  are 10 nm, 1.1 nm, 1 nm or less, 1.4 nm, and 0.3 nm, respectively. 
         [0028]    The bottom-pinned perpendicular MTJ device  100 B illustrated in  FIG. 1B  includes the same layers as those of the top-pinned perpendicular MTJ device  100 A. The CoFeB layer  106  as a reference layer (a magnetization fixed layer) is provided on the side far from the substrate  101 , and the multilayers  110 B and  110 A are therefore provided between the substrate  101  and CoFeB layer  106 . Additionally, the bottom-pinned perpendicular MTJ device  100 B further includes a Ru layer  116  as a seed layer under the multilayer  110 B. The Ru layer  116  is a layer to improve the crystalline orientation of the [Co/Pt] multilayer  110 B. The structures illustrated in  FIGS. 1A and 1B  are just examples, and the [Co/Pt] multilayers  110 A and  110 B may be made of materials having perpendicular magnetization. Instead of the [Co/Pt] multilayers  110 A and  110 B, TbFeCo, [Co/Ni] multilayers, CoPt or FePt, which are ordered alloys, or the like, may be used, for example. 
         [0029]    The configurations of the perpendicular MTJ devices (of top-pinned and bottom-pinned types) according to the embodiment are not limited to the configurations illustrated herein and any change, such as increase or decrease in the number of layers, change in the constituent materials of the layers, and reversing the order of layers upside down, may be made as long as it does not degrade the functions of the perpendicular MTJ device. 
         [0030]    Next, a description is given of separate film formation in the method of manufacturing the top-pinned perpendicular MTJ device  100 A, which is a perpendicular MTJ device, using  FIGS. 2A to 2D . 
         [0031]    In the method of manufacturing the top-pinned perpendicular MTJ device  100 A according to the embodiment, the part concerning a first stacked structure  10  of the top-pinned perpendicular MTJ device  100 A is first formed on the substrate, and property inspection is performed. The part concerning a second stacked structure  20  of the top-pinned perpendicular MTJ device  100 A is then formed, and different property inspection is performed. Herein, the first stacked structure  10  includes at least the CoFeB layer  104 , MgO layer  105 , and CoFeB layer  106 , and the second stacked structure  20  includes at least the superlattice [Co/Pt] multilayers  110 A and  110 B. 
         [0032]    To be specific, the first stacked structure  10  is formed on the substrate  101  under vacuum in a first film formation apparatus. The substrate with the first stacked structure  10  formed thereon is then taken out of the first film formation apparatus to be exposed to the atmosphere and is inspected in terms of the MR properties. The substrate is then etched back under vacuum in another second film formation apparatus, and the second stacked structure  20  is further formed on the same, producing the top-pinned perpendicular MTJ device  100 A. The top-pinned perpendicular MTJ device  100 A is then taken out of the second film formation apparatus and is inspected in terms of the perpendicular magnetic anisotropy properties. 
         [0033]    Herein, the inspection of the MR properties is performed using a current in-plane tunneling (CIPT) measuring device or the like after a lower electrode layer necessary for the inspection is formed on the substrate with the first stacked structure  10  not yet formed thereon and then an upper electrode layer necessary for the inspection is formed on the substrate with the first stacked structure  10  formed thereon. The inspection of the perpendicular magnetic anisotropy properties is performed using a vibrating sample magnetometer (VSM) measuring device or the like. The property inspections are performed in a cleanroom with a low level of dust. The different second film formation apparatus does not need to be used if both of the first and second stacked structures  10  and  20  can be formed by only the first film formation apparatus to produce the top-pinned perpendicular MTJ device  100 A. 
         [0034]    The perpendicular MTJ device is separated into the first and second stacked structures  10  and  20  based on the Ta layer (also referred to as SpacerTa)  107 . The separation may be based on another layer if the first stacked structure  10  includes at least the CoFeB layer  104 , MgO layer  105 , and CoFeB layer  106  and the second stacked structure  20  includes at least the superlattice [Co/Pt] multilayers  110 A and  110 B. As illustrated in  FIG. 2A , the Ta layer  107  of the first stacked structure  10  needs to be made comparatively thick in light of partially removing the Ta layer  107  by etching. Controlling the thickness of each of the CoFeB layer  104 , MgO layer  105 , CoFeB layer  106 , and superlattice [Co/Pt] multilayers  110 A and  110 B within 2 nm enables the perpendicular MTJ device to fulfill the function thereof. In the embodiment, the Ta layer  107  is formed into a thickness of about 3 nm at first and is then etched back to be controlled to 2 nm or less. However, the Ta layer  107  may be etched back by 1 nm or more. 
         [0035]    The thickness of oxide film generated in the surface of the Ta layer  107  through exposure to the atmosphere depends on diffusion of oxygen into the Ta layer  107 , which correlates to the time when the Ta layer  107  is left under the atmosphere, the atmosphere temperature, and the like. How thick the oxide film will be formed in the Ta layer  107  can be experimentally found based on the inspection time, environmental temperature, and the like of the property inspection after the treatment conducted in the first film formation apparatus. Accordingly, it is also experimentally found to what extent the Ta layer  107  needs to be removed in the etch-back process. 
         [0036]    As illustrated in  FIG. 2B , after the process to etch a part of the Ta layer  107  (etch-back process), the second stacked structure  20  is formed starting from the Co layer of the [Co/Pt] multilayer  110 A, so that the top-pinned perpendicular MTJ device  100 A illustrated in  FIG. 1A  is eventually produced. 
         [0037]    To be specific, in the manufacture of the top-pinned perpendicular MTJ device  100 A, the substrate on which the first stacked structure  10  is formed up to the Ta layer  107  under vacuum is taken out of the first film formation apparatus and is then inspected in terms of the MR properties in the cleanroom under the atmosphere. The substrate is then introduced into the second film formation apparatus, and a part (an oxidized part) of the Ta layer  107  is etched under vacuum (etch-back process). Thereafter, the upper layers are formed starting from a Co layer of the [Co/Pt] multilayer  110 A. After the top electrode  112  is formed, the substrate is taken out of the second film formation apparatus and is inspected in terms of the perpendicular magnetic anisotropy properties. 
         [0038]    Note that as illustrated in  FIG. 2C , after a part of the Ta layer  107  is etched (etch-back process), the upper layers may be formed starting from a Ta layer  107 A. Note that the Ta layers  107  and  107 A are formed under the same film formation conditions using the same material. Alternatively, as illustrated in  FIG. 2D , the CoFeB layer  106  may be made comparatively thick and the thus-obtained substrate is taken out of the first film formation apparatus and undergoes the property inspection. Thereafter, in the second film formation apparatus, a part of the CoFeB layer  106  is etched and the upper layers may be formed starting from the Ta layer  107 . 
         [0039]    Next, a description is given of separate film formation in the method of manufacturing the perpendicular MTJ device (the bottom-pinned perpendicular MTJ device  100 B) using  FIGS. 3A to 3C . 
         [0040]    Similarly to the aforementioned method, in the method of manufacturing the bottom-pinned perpendicular MTJ device  100 B according to the embodiment, the property inspection is performed after the part concerning the second stacked structure  21  of the bottom-pinned perpendicular MTJ device  100 B is formed on the substrate, and the different property inspection is then performed after the part concerning the first stacked structure  11  of the bottom-pinned perpendicular MTJ device  100 B is further formed. Herein, the first stacked structure  11  includes at least the CoFeB layer  104 , MgO layer  105 , and CoFeB layer  106 , and the second stacked structure  21  includes at least the superlattice [Co/Pt] multilayers  110 A and  110 B. 
         [0041]    The Ta layer  107  of the second stacked structure  21  is made comparatively thick as illustrated in  FIG. 3A . After the process to etch a part of the Ta layer  107  (etch-back process) as illustrated in  FIG. 3B , the first stacked structure  11  is formed starting from the CoFeB layer  106  of the first stacked structure  11 , so that the bottom-pinned perpendicular MTJ device  100 B illustrated in  FIG. 1B  is eventually produced. 
         [0042]    In the manufacture of the bottom-pinned perpendicular MTJ device  100 B illustrated in  FIGS. 3A and 3B , the substrate on which the second stacked structure  21  is formed up to the Ta layer  107  is taken out of the first film formation apparatus and is then inspected in terms of the perpendicular magnetic anisotropy properties in the cleanroom under the atmosphere. The substrate is then introduced into the second film formation apparatus, and a part (an oxidized part) of the Ta layer  107  is etched under vacuum (the etch-back process). Thereafter, the upper layers are formed starting from the CoFeB layer  106 . After the top electrode  112  is formed, the substrate is taken out of the second film formation apparatus and is inspected in terms of the MR properties. 
         [0043]    As illustrated in  FIG. 3C , after forming a Co layer that is the topmost layer of the [Co/Pt] multilayer  110 A of the second stacked structure  21  comparatively thick, the substrate may be taken out of the first film formation apparatus and then be inspected for properties. Thereafter, the first stacked structure  11  is formed starting from the Ta layer  107  after a part of the Co layer is etched in the second film formation apparatus. 
         [0044]      FIG. 4  is a schematic configuration diagram of a manufacturing system  400  including single-core sputtering apparatuses  410  and  420  as the first and second film formation apparatuses used in the method of manufacturing a perpendicular MTJ device according to the embodiment. 
         [0045]    In manufacture of the top-pinned perpendicular MTJ device  100 A, the sputtering apparatus  410  is the first film formation apparatus to form the first stacked structure  10 , and the sputtering apparatus  420  is the second film formation apparatus to form the second stacked structure  20 . On the other hand, in manufacture of the bottom-pinned perpendicular MTJ device  100 B, the sputtering apparatus  410  is the first film formation apparatus to form the second stacked structure  21 , and the sputtering apparatus  420  is the second film formation apparatus to form the first stacked structure  11 . 
         [0046]    The manufacturing system  400  further includes property inspection apparatuses  430  and  440 . In manufacture of the top-pinned perpendicular MTJ device  100 A, the property inspection apparatus  430  is a CIPT measuring device for inspection of the MR properties, and the property inspection apparatus  440  is a VSM measuring device for inspection of the perpendicular magnetic anisotropy properties. On the other hand, in manufacture of the bottom-pinned perpendicular MTJ device  100 B, the property inspection apparatus  430  is a VSM measuring device, and the property inspection apparatus  440  is a CIPT measuring device. The following description relates to the manufacturing system  400  for the top-pinned perpendicular MTJ device  100 A unless otherwise noted. The manufacturing system  400  for the bottom-pinned perpendicular MTJ device  100 B is the same as that for the top-pinned perpendicular MTJ device  100 A other than the differences in the order of formed layers and target materials. 
         [0047]    The sputtering apparatus  410  includes an equipment front end module (EFEM)  411 , a load lock chamber  412 , a vacuum transfer chamber  413 , an etching chamber  414 , metal deposition chambers  415  to  417 , an oxidation chamber  418 , and a degassing chamber  419 . Each chamber is kept evacuated. 
         [0048]    The EFEM  411  transports a substrate into and out of the load lock chamber  412 . The load lock chamber  412  adjusts the inside of the chamber to vacuum and transports the substrate to the vacuum transfer chamber  413 . The vacuum transfer chamber  413  includes a robot loader to load and unload the substrate to a robot feeder (not illustrated) within each chamber  414  to  419 . The etching chamber  414  performs dry etching such as capacitively-coupled plasma (CCP) etching, inductively-coupled plasma (ICP) etching, or ion beam etching. In the metal deposition chambers  415  to  417 , the target materials used to form the layers of the first stacked structure  10 , such as a Ta target, a CoFeB target, and an Mg target, for example, are provided, and each layer is formed on the substrate by sputtering. The oxidation chamber  418  performs oxidation for the substrate. 
         [0049]    The sputtering apparatus  420  includes an EFEM  421 , a load lock chamber  422 , a vacuum transfer chamber  423 , an etching chamber  424 , metal deposition chambers  425  to  428 , and a degassing chamber  429 . The inside of each chamber is kept evacuated. The EFEM  421 , load lock chamber  422 , vacuum transfer chamber  423 , and degassing chamber  429  are the same as those of the sputtering apparatus  410 . In the metal deposition chambers  425  to  428 , the target materials used to form each layer of the second stacked structure  20 , such as a Co target, a Pt target, a Ru target, and a Ta target, for example, are provided, and each layer is formed on the substrate by sputtering. 
         [0050]    The substrate is transported between the sputtering apparatuses  410  and  420  and the property inspection apparatuses  430  and  440  through a transfer path (not illustrated) or by an operator. 
         [0051]    Hereinafter, the embodiment is described in more detail. First, a substrate  101  is transported into the load lock chamber  412  through the EFEM  411  of the first film formation apparatus  410 . The robot loader of the vacuum transfer chamber  413  is then driven to sequentially move the substrate from the load lock chamber  412  to the predetermined substrate treatment chambers  414  to  419 , thus forming the first stacked structure  10  (or the second stacked structure  21 ). 
         [0052]    In manufacture of the top-pinned perpendicular MTJ device  100 A, etching is performed in the first film formation apparatus  410  to remove impurities and the like attached to the substrate  101 . Thereafter, the bottom electrode  102 , Ta layer  103 , CoFe layer  104 , MgO layer  105 , CoFeB layer  106  as the reference layer, and Ta layer  107  are sequentially formed on the substrate  101  by sputtering, thus forming the first stacked structure  10 . 
         [0053]    On the other hand, in manufacture of the bottom-pinned perpendicular MTJ device  100 B, etching is performed in the first film formation apparatus  410  to remove impurities and the like attached to the substrate  101 . Thereafter, the bottom electrode  102 , Ta layer  103 , and the multilayers  110 A and  110 B are sequentially formed on the substrate  101  by sputtering, thus forming the second stacked structure  21 . 
         [0054]    Next, the substrate is ejected from the first film formation apparatus  410  through the load lock chamber  412  and EFEM  411  to be exposed to the atmosphere. The substrate then undergoes the property inspection (the inspection of the MR properties or perpendicular magnetic anisotropy properties) in the property inspection apparatus  430 . Thereafter, the substrate is transferred into the load lock chamber  422  through the EFEM  421  of the second film formation apparatus  420 . The robot loader of the vacuum transfer chamber  423  is driven to move the substrate from the load lock chamber  422  sequentially to the predetermined substrate treatment chambers  424  to  429 , thus forming the second stacked structure  20  (or the first stacked structure  11 ). 
         [0055]    In the manufacture of the top-pinned perpendicular MTJ device  100 A, etching is performed to remove impurities attached to the Ta layer  107 , oxide film formed in the Ta layer, and the like in the second film formation apparatus  420 . Thereafter, the multilayer  110 A, Ru layer  110 C, multilayer  110 B, Ru layer  115 , Ta layer  111 , and top electrode  112  are sequentially formed by sputtering. On the other hand, in the manufacture of the bottom-pinned perpendicular MTJ device  100 B, etching is performed to remove impurities attached to the Ta layer  107 , oxide film formed in the Ta layer, and the like in the second film formation apparatus  420 . Thereafter, the CoFe layer  106 , MgO layer  105 , CoFeB layer  104 , Ta layer  111 , and top electrode  112  are sequentially formed by sputtering. The eventually formed top-pinned perpendicular MTJ device  100 A (or bottom-pinned perpendicular MTJ device  100 B) is ejected from the second film formation apparatus  420  and is then inspected in terms of the perpendicular magnetic anisotropy properties (or the MR properties) in the property inspection apparatus  440 . 
         [0056]    The MgO layer  105  may be formed by radio-frequency (RF) sputtering using an MgO target or may be formed in such a manner that an Mg layer is formed on the CoFeB layer by sputtering using an Mg target and is then oxidized. The film formation and oxidation of Mg may be performed in the same substrate treatment chamber of the first film formation apparatus  410  (or the second film formation apparatus  420 ) or may be performed in different substrate treatment chambers that use a metal deposition chamber and an oxidation chamber. 
         [0057]    The film formation apparatus used in the method of manufacturing a perpendicular MTJ device may be a double-core sputtering apparatus  500  as illustrated in  FIG. 5 . The double-core sputtering apparatus  500  can also implement the method of manufacturing a perpendicular MTJ device according to the embodiment. By using the double-core sputtering apparatus  500 , the number of chambers capable of performing deposition per film formation apparatus is increased, and more perpendicular MTJ devices can be manufactured than manufactured by the single-core sputtering apparatus. 
         [0058]      FIG. 6  is a flowchart for explaining the method of manufacturing the top-pinned perpendicular MTJ device  100 A, which is the perpendicular MTJ device according to the embodiment. 
         [0059]    In S 601 , the bottom electrode  102 , Ta layer  103 , CoFeB layer  104 , MgO layer  105 , CoFeB layer  106 , and Ta layer  107  are sequentially formed on the substrate  101  in the first film formation apparatus  410 , thus forming the first stacked structure  10 . As described above, the first stacked structure  10  may be formed in such a manner that the CoFeB layer  106  is made comparatively thick and the Ta layer  107  is not formed as the first stacked structure  10  but formed as the second stacked structure  20 . 
         [0060]    In S 602 , the substrate with the first stacked structure  10  formed thereon is taken out of the first film formation apparatus  410  to be exposed to the atmosphere, and the electrode layer and the like necessary for the property inspection are formed thereon. In S 603 , inspection of the MR properties is performed in the property inspection apparatus  430 , which is a CIPT measuring device. Accordingly, the property inspection is performed for the substrate with only the first stacked structure  10  formed thereon before the second stacked structure  20  is formed. This facilitates management of the properties attributed to the first stacked structure  10 . 
         [0061]    Next, in step S 604 , etching is performed in the second film formation apparatus  420  after the property inspection for the first stacked structure  10  is completed because the topmost layer (the Ta layer  107  or CoFeB layer  106 ) of the first stacked structure  10  has been exposed to the atmosphere and naturally oxidized. The etching is dry etching using Ar gas, such as capacitively-coupled plasma (CCP) etching, inductively-coupled plasma (ICP) etching, or ion beam etching, for example. 
         [0062]    In S 605 , the multilayer  110 A, Ru layer  110 C, multilayer  110 B, Ru layer  115 , Ta layer  111 , and top electrode  112  (in addition, the Ta layer  107  if necessary) are formed in the second film formation apparatus  420 , thus forming the second stacked structure  20 . Since the property inspection (MR properties) for the first stacked structure  10  is already performed, in  5606 , inspection of the properties different from the MR properties, that is, perpendicular magnetic anisotropy properties, is performed in the property inspection apparatus  440 , which is a VSM measuring device, after the second stacked structure  20  is formed. 
         [0063]      FIG. 7  is a flowchart for explaining the method of manufacturing the bottom-pinned perpendicular MTJ device  100 B, which is the perpendicular MTJ device according to the embodiment. 
         [0064]    In S 701 , the bottom electrode  102 , Ta layer  103 , Ru layer  106 , multilayer  110 B, Ru layer  110 C, multilayer  110 A, and Ta layer  107  are sequentially formed on the substrate  101  in the first film formation apparatus  410 , thus forming the second stacked structure  21 . As described above, the second stacked structure  21  may be formed in such a manner that the Co layer at the topmost layer of the multilayer  110 A is made comparatively thick and the Ta layer  107  is not formed as the second stacked structure  21  but formed as the first stacked structure  11 . 
         [0065]    In S 702 , the substrate with the second stacked structure  21  formed thereon is taken out of the first film formation apparatus  410  to be exposed to the atmosphere, and the electrode layer and the like necessary for the property inspection are formed thereon. In S 703 , inspection of the perpendicular magnetic anisotropy properties is performed in the property inspection apparatus  430 , which is a VSM measuring device. The property inspection is thus performed for the substrate with only the second stacked structure  21  formed thereon before the first stacked structure  11  is formed. This facilitates management of the properties attributed to the second stacked structure  21 . 
         [0066]    Next, in step S 704 , etching is performed in the second film formation apparatus  420  after the property inspection for the second stacked structure  21  is completed because the topmost layer (the Ta layer  107  or Co layer) of the second stacked structure  21  has been exposed to the atmosphere and naturally oxidized. The etching is dry etching using Ar gas, such as capacitively-coupled plasma (CCP) etching, inductively-coupled plasma (ICP) etching, or ion beam etching, for example. 
         [0067]    In S 705 , the CoFeB layer  106 , MgO layer  105 , CoFeB layer  104 , Ta layer  111 , and top electrode  112  (in addition, the Ta layer  107  if necessary) are formed in the second film formation apparatus  420 , thus forming the first stacked structure  11 . Since the property inspection for the second stacked structure  21  (perpendicular magnetic anisotropy properties) is already performed, in  5706 , inspection of the MR properties is performed in the property inspection apparatus  440 , which is a CIPT measuring device, after the first stacked structure  11  is formed. 
         [0068]    As described above, by separately performing the property inspections for the perpendicular MTJ device in the middle and after manufacture thereof, inspection of the MR properties is performed when the first stacked structure including the CoFeB layer  104 , MgO layer  105 , and CoFeB layer  106  is formed, and inspection of the perpendicular magnetic anisotropy properties is performed when the second stacked structure including the multilayers  110 A and  110 B is formed. Accordingly, in order that products (the substrates with only the first or second stacked structure formed thereon or the substrates with the first and second stacked structures formed) by the apparatuses that form the first and second stacked structures have desired properties, it is only necessary to adjust the conditions of each apparatus (control conditions of sputtering and the like), the film thickness and the material type of each layer, and the like. This clarifies the roles of the apparatuses and simplifies the management of the properties of perpendicular MTJ devices. 
         [0069]    For example, the perpendicular magnetic anisotropy properties are guaranteed only by controlling the thickness of each layer at forming the second stacked structure, and the second stacked structure can be formed even if the film formation apparatus to form the first stacked structure is malfunctioning. Moreover, by increasing the number of modules performing substrate treatment in each apparatus used in film formation, the throughput can be increased. For example, using the double-core sputtering apparatus  500  illustrated in  FIG. 5  can double the throughput compared with the single-core sputtering apparatus  410  or  420  illustrated in  FIG. 4 . 
         [0070]    In the conventional method, property inspections of both the MR properties and perpendicular magnetic anisotropy properties are performed for a perpendicular MTJ device with both the first and second stacked structures formed thereon. Accordingly, in the case where the MR properties attributed to the first stacked structure are different from desired values, for example, the entire perpendicular MTJ device needs to be discarded even if the perpendicular magnetic anisotropy properties attributed to the second stacked structure are normal. The film formation treatment to form the second stacked structure is wasted, resulting in cost of production loss. However, according to the method of manufacturing a perpendicular MTJ device according to the embodiment, in case of trouble of film formation apparatuses, it is possible to determine that the apparatus which has formed the first stacked structure is malfunctioning when the MR properties include a problem, or it is possible to determine that the apparatus which has formed the second stacked structure is malfunctioning when the perpendicular magnetic anisotropy properties include a problem. It is therefore possible to easily identify the cause of the malfunctioning apparatus, thus reducing the cost of production loss in case of trouble. 
       Other Embodiment 
       [0071]    The method of manufacturing a perpendicular MTJ device according to the present invention is not limited to manufacture of perpendicular MTJ devices including the configurations illustrated in  FIGS. 1A and 1B  and is applicable to manufacture of any type of perpendicular MTJ devices. Using the manufacturing method according to the present invention can reduce the cost concerning controlling the conditions of the film formation apparatus for perpendicular MTJ devices having desired properties.