Abstract:
A magnetic device includes a substrate, a sensing block and a repair layer. The substrate has a bottom electrode, a registration layer and a barrier layer disposed on the registration layer. The sensing block is patterned to distribute on the barrier layer. The repair layer is disposed substantially on the barrier layer, wherein the barrier layer is configured to have a tunneling effect when a bias voltage exists between the sensing block and the registration layer.

Description:
PRIORITY CLAIM AND CROSS-REFERENCE 
       [0001]    This application is a Continuation-in-Part (CIP) application of U.S. application Ser. No. 13/686,663 filed on Nov. 27, 2012, entitled “Magnetic Device with a Substrate, a Sensing Block and a Repair Layer”, the disclosure of which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present disclosure generally relates to a magnetic device, and particularly to a memory storage device that uses a magnetic moment to store data. 
       BACKGROUND 
       [0003]    Ferromagnetic material is utilized to manufacture a non-volatile memory device, such as magnetoresistive RAM (MRAM). Since its discovery in 1970, the tunneling effect of the magnetic tunnel junction (MTJ) has caused a dramatic change in the use of magnetic memory devices. The MTJ usually consists of at least three layers, which are the pinned layer, the barrier layer and the free layer. As a result, the stored memory in the domain can be written or read by sensing the current tunneling through the barrier. 
         [0004]    The correctivity or the ratio of the self spin-polarization is one of the major concerns regarding the efficiency and accuracy of when to read or write the memory storage domain. One possible reason for the degraded performance is attributed to the damage on the film during manufacturing. Etching or plasma bombardments attacking the exposure surface during the process or oxidation of the post-etched film surface are probable factors. It was reported that even introducing a cap layer, such as silicon nitride, on the device right after the etching process would cause degradation. Therefore, in order to improve the performance of a magnetic memory device, the process of repairing the damage or reducing the oxidation of the device is essential. 
       SUMMARY OF THE INVENTION 
       [0005]    The objective of the present disclosure is to provide a magnetic device including a substrate, a sensing block and a repair layer. The substrate has a bottom electrode, a registration layer and a barrier layer disposed on the registration layer. The sensing block is patterned to distribute on the barrier layer. The repair layer is disposed on the barrier layer and the registration layer is configured to store data. 
         [0006]    The objective of another embodiment of the present disclosure is to provide a racetrack magnetic memory device including a substrate, a sensing block and a repair layer. The substrate has a bottom electrode, a registration layer and a barrier layer disposed on the registration layer. The sensing block is patterned to distribute on the barrier layer. The repair layer is disposed on the barrier layer and the registration layer is configured to store data. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The invention will be described according to the appended drawings in which: 
           [0008]      FIG. 1  illustrates a magnetic device according to the present disclosure; 
           [0009]      FIG. 2  illustrates other magnetic devices according to the present disclosure; 
           [0010]      FIGS. 3-6  depict the process to manufacture an embodiment according to the present disclosure; 
           [0011]      FIG. 3  illustrates provision of a substrate, a registration layer, a barrier layer according to the present disclosure; 
           [0012]      FIG. 4  illustrates arrangement of a mask over a sensing block according to the present disclosure; 
           [0013]      FIG. 5  illustrates patterning of a sensing block according to the present disclosure; 
           [0014]      FIG. 5A  illustrates etching of some portions of a registration layer and/or a barrier layer according to the present disclosure; 
           [0015]      FIG. 6  illustrates deposition of a repair layer over a sensing block and a barrier layer according to the present disclosure; 
           [0016]      FIG. 6A  illustrates deposition of a repair layer over a sensing block and a substrate according to the present disclosure;  FIG. 7  illustrates a racetrack magnetic memory device according to the present disclosure; 
           [0017]      FIG. 8  illustrates racetrack magnetic memory devices having a multi-layered stack sensing block; 
           [0018]      FIG. 9  illustrates racetrack magnetic memory devices having a repair layer. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The embodiments of the present invention are described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific exemplary embodiments by which the invention may be practiced. This invention may, however, 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 invention to those skilled in the art. As used herein, the term “or” is an inclusive “or” operator, and is equivalent to the term “and/or,” unless the context clearly dictates otherwise. In addition, throughout the specification, the meaning of “a,” “an,” and “the” include plural references. The term “coupled” implies that the elements may be directly connected together or may be coupled through one or more intervening elements. 
         [0020]    The first embodiment according to the present disclosure can be referred to  FIG. 1 . A magnetic device  10  has a substrate  100 , a sensing block  200  and a repair layer  300 . In some embodiments, the magnetic device  10  includes a bottom electrode. In some embodiments, the bottom electrode is disposed above substrate  100 . The sensing block  200  is disposed above the barrier layer  120 . In another embodiment, there are a plurality of sensing blocks  200  disposed on the substrate  100 . The sensing block  200  can be a multi-layered film stack and the sequence of the stacking films is not limited as the illustrated embodiments. 
         [0021]    As shown in  FIG. 2 , the multi-layered stack sensing block  200  includes at least four different thin film layers; there are a first ferromagnetic layer  220  on a barrier layer  120 , a non-magnetic layer  240  disposed on the first ferromagnetic layer  220 , a second ferromagnetic layer  260  on the non-magnetic layer  240 , and an anti-ferromagnetic layer  280  on the second ferromagnetic layer  260 . A fixed layer is shown collectively as layers  220 - 280  in  FIG. 2  which comprises a synthetic anti-ferromagnetic (SAF) structure. The non-magnetic metal layer  240  can be a metal layer and made with material such as Ru, Rh, Cu, etc. The first ferromagnetic layer  220  and the second ferromagnetic layer  260  is made of any ferromagnetic material with in-plane magnetic anisotropy (IMA) such as CoFe, CoFeB or bilayer of CoFe/CoFeB or CoFeB/Fe. The anti-ferromagnetic layer  280  can be made with material such as PtMn, IrMn, NiMn, etc. Moreover, a registration layer  150  is disposed on the substrate  100 . The barrier layer  120  is sandwiched between the registration layer  150  and the sensing block  200 . In some embodiments, the bottom electrode is disposed between the substrate  100  and the registration layer  150 . In an embodiment, the barrier layer  120  is between the registration layer  150  and the first ferromagnetic layer  220 . The registration layer  150  is made with ferromagnetic materials with IMA such as permalloy, Fe, Co, nickel (Ni), CoFe, CoFeB or any kind of magnetic alloy. The registration layer  150  can be optionally used to store memory according to the injected electric current from a write line (not shown) which electrically connected to the registration layer  150 . The barrier layer  120  is made with electric insulating material, such as AlOx, MgxOy, etc. The thickness of the barrier layer  120  is around  10 A so as to have electrons tunneling through the barrier layer  120  if a bias voltage is applied between the registration layer  150  and the sensing block  200 . The repair layer  300  is disposed on the barrier layer  120 . 
         [0022]    The process of manufacturing the magnetic device  10  can be accomplished in various ways in accordance to each user&#39;s preference. In one embodiment according to the present disclosure, thin film deposition such as PVD, CVD, etc. is utilized to form the registration layer  150 , the barrier layer  120  and the films constructing the sensing block stack  200  in different steps. As shown in  FIG. 3 , the aforementioned films are blanket deposited sequentially on the substrate  100 . A mask step (mask  50 ) is arranged on the top of the film stack as shown in  FIG. 4 . The mask step is followed by an etching step, preferred as a dry etch in the present embodiment. 
         [0023]    In some embodiments, a portion of the sensing block  200  is carved out and finally a desired pattern forms as shown in  FIG. 5 . In some embodiments as in  FIG. 5A , some portions of the registration layer  150  and/or the barrier layer  120  without coverage of the mask  50  are also etched. The sensing block  200  can act as a terminal to read out the data if there is any current tunneling from the registration layer  150  into the sensing block  200 , reversely, the registration layer  150  also can act as a terminal to read out the data if there is any current tunneling from the sensing block  200  into the registration layer  150 . The repair layer  300  can form subsequently after the etching step is accomplished. In some embodiments, the repair layer  300  is preferably disposed on the barrier layer  120  with a thin film deposition process as shown in  FIG. 6 . In some embodiments as in  FIG. 6A , the repair layer  300  is disposed conformal to the substrate  100 , the registration layer  150 , the barrier layer  120  and the sensing block  200 . 
         [0024]    The material which is selected to form the repair layer  300  may possess a standard oxidation potential value, Er, which is greater than the standard oxidation potential value of the registration layer  150 , Eb. In an exemplary embodiment, the oxidation potential value, Er of the repair layer is greater than 0.44V. 
         [0025]    In another example, the material for the repair layer  300  can be metal and is preferably selected from Mg, Al, Ti, Mn, Zn, Cr, Ta, or the combination thereof, resulting in the oxygen concentration in the barrier layer  120  to be lowered after coming in contact with the repair layer  300 . 
         [0026]    In another embodiment, the alloy of Mg, Al, Ti, Mn, Zn, Cr, or Ta is used to form the repair layer  300 . Moreover, metal oxide is also an option to form the repair layer  300 . In one embodiment, all possible oxidation states of the following metals: Mg, Al, Ti, Mn, Zn, Cr, Ta, or the combination thereof can be chosen to achieve the same objective of the present disclosure. 
         [0027]      FIG. 7  depicts another embodiment according to the present disclosure. A racetrack magnetic memory device  20  has a substrate  100 , a registration layer  150  disposed on the substrate  100 , and a barrier layer  120  disposed on the registration layer is  150 . In some embodiments, the racetrack magnetic memory device  20  includes a bottom electrode. In some embodiments, the bottom electrode is disposed above substrate  100 . In some embodiments, the bottom electrode is disposed between the substrate  100  and the registration layer  150 . A sensing block  200  is disposed on the barrier layer  120 . In another embodiment, there is a plurality of sensing blocks  200  disposed on the barrier layer  120 . The sensing block  200  can be a multi-layered film stack. The registration layer  150  and the barrier layer  120  are etched to be like a racetrack. 
         [0028]      FIG. 8  illustrated another racetrack magnetic memory device according to the present disclosure. There are four different thin film layers, a first ferromagnetic layer  220  on a barrier layer  120 , a non-magnetic layer  240  disposed on the first ferromagnetic layer  220 , a second ferromagnetic layer  260  on the non-magnetic layer  240 , and an anti-ferromagnetic layer  280  on the second ferromagnetic layer  260 . A fixed layer is shown collectively as layers  220 - 280  in  FIG. 8  which comprises a synthetic anti-ferromagnetic (SAF) structure. The non-magnetic metal layer  240  can be a metal layer and made with material such as Ru, Rh, Cu, etc. The first ferromagnetic layer  220  and the second ferromagnetic layer  260  is made of any ferromagnetic material with in-plane magnetic anisotropy (IMA) such as CoFe, CoFeB or bilayer of CoFe/CoFeB or CoFeB/Fe. The anti-ferromagnetic layer  280  can be made with material such as PtMn, IrMn, NiMn, etc. The registration layer  150  can be optionally used to store memory according to the injected electric current from a write line (not shown) which electrically connected to the registration layer  150 . The barrier layer  120  is made with electric insulating material, such as AlOx, MgxOy, etc. The thickness of the barrier layer  120  is around 10 A so as to have electrons tunneling through the barrier layer  120  if a bias voltage is applied between the registration layer  150  and the sensing block  200 . 
         [0029]    The process to manufacture the racetrack magnetic memory device  20  adopts similar steps as utilized for the magnetic device  10 . The differences may be a different mask or few more steps that are required in order to form the racetrack memory. For example, an etching step may be provided to carve out a portion of each blanket film for the registration layer  150  and the barrier layer  120  to form a racetrack. 
         [0030]      FIG. 9  shows the deposition of a repair layer  300  on the barrier layer  120  as illustrated in  FIG. 8 . The material which is selected to form the repair layer  300  may possess a standard oxidation potential value, Er, which is greater than the standard oxidation potential value of the registration layer  150 , Eb. In an exemplary embodiment, the oxidation potential value, Er, of the repair layer is greater than 0.44V. 
         [0031]    In another example, the material for the repair layer  300  can be metal and is preferably selected from Mg, Al, Ti, Mn, Zn, Cr, Ta, or the combination thereof, resulting in the oxygen concentration in the barrier layer  120  to be lowered after coming in contact with the repair layer  300 . 
         [0032]    In another embodiment, the alloy of Mg, Al, Ti, Mn, Zn, Cr, or Ta is used to form the repair layer  300 . Moreover, metal oxide is also an option to form the repair layer  300 . In one embodiment, all possible oxidation states of the following metals: Mg, Al, Ti, Mn, Zn, Cr, Ta, or the combination thereof can be chosen to achieve the same objective of the present disclosure. 
         [0033]    The methods and features of this invention have been sufficiently described in the above examples and descriptions. It should be understood that any modifications or changes without departing from the spirit of the invention are intended to be covered in the protection scope of the invention.