Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority from Japanese Patent Application No. 2009-296224 filed on Dec. 25, 2009, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The embodiments discussed herein relate to a method of manufacturing a semiconductor device having magnetic elements. 
         [0004]    2. Description of Related Art 
         [0005]    In a magnetotunnel junction (MTJ) including two ferromagnetic layers having a thin insulating layer therebetween, the tunnel resistance varies depending on the relative directions of magnetization of the two ferromagnetic layers. A magneto-resistive random access memory (MRAM) may be a semiconductor device where magnetic elements (MTJ elements) having MTJs utilizing a tunnel magneto resistance (TMR) effect are arranged in a matrix form as a memory cell. 
         [0006]    Related art is disclosed in, for example, Japanese Laid-open Patent Publication Nos. 2006-253303, 2009-43831, 2006-261592, 2009-16417, 2008-135619, and 2006-5152. 
       SUMMARY 
       [0007]    One aspect of the embodiments is a method of manufacturing a semiconductor device including: forming a first conductive layer on a semiconductor substrate; forming a magnetic film on the first conductive layer; forming a second conductive layer on the magnetic film; forming a first mask layer on the second conductive layer; patterning the second conductive layer; patterning the magnetic film; forming a first insulating film on the first conductive layer to cover a side surface of the patterned second conductive layer and the patterned magnetic film; forming a second mask layer on the first insulating film to cover the patterned second conductive layer, the patterned magnetic film, and the first insulating film; patterning the first insulating film; patterning the first conductive layer; forming a second insulating film on the semiconductor substrate to cover the patterned second conductive layer, the patterned magnetic film, and the patterned first conductive layer; and forming a third insulating film on the second insulating film. 
         [0008]    Additional advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become more apparent to those skilled in the art upon examination of the following or upon learning by practice of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIGS. 1A to 1C  illustrate an exemplary method of manufacturing an MRAM; 
           [0010]      FIGS. 2A to 2C  illustrate an exemplary method of manufacturing an MRAM; 
           [0011]      FIGS. 3A to 3D  illustrate an exemplary method of manufacturing an MRAM; 
           [0012]      FIGS. 4A to 4D  illustrate an exemplary method of manufacturing an MRAM; 
           [0013]      FIGS. 5A to 5D  illustrate an exemplary method of manufacturing an MRAM; 
           [0014]      FIGS. 6A to 6D  illustrate an exemplary method of manufacturing an MRAM; 
           [0015]      FIGS. 7A to 7C  illustrate an exemplary method of manufacturing an MRAM; 
           [0016]      FIGS. 8A to 8C  illustrate an exemplary method of manufacturing an MRAM; 
           [0017]      FIG. 9  illustrates an exemplary method of manufacturing an MRAM; 
           [0018]      FIG. 10  illustrates an exemplary MRAM; 
           [0019]      FIGS. 11A to 11C  illustrate an exemplary method of manufacturing a MRAM; 
           [0020]      FIGS. 12A and 12B  illustrate an exemplary MRAM; 
           [0021]      FIGS. 13A to 13C  illustrate an exemplary method of manufacturing an MRAM; 
           [0022]      FIGS. 14A to 14C  illustrate an exemplary method of manufacturing an MRAM; 
           [0023]      FIGS. 15A to 15C  illustrate an exemplary method of manufacturing an MRAM; 
           [0024]      FIGS. 16A to 16C  illustrate an exemplary method of manufacturing an MRAM; 
           [0025]      FIGS. 17A to 17C  illustrate an exemplary method of manufacturing an MRAM; 
           [0026]      FIGS. 18A to 18C  illustrate an exemplary method of manufacturing an MRAM; and 
           [0027]      FIG. 19  illustrates an exemplary method of manufacturing an MRAM. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0028]    The memory cell of an MRAM includes selection transistors, an MTJ element, upper and lower electrodes coupled so as to have the MTJ element therebetween, and a magnetic field-generating layer for magnetization reversal by generating a magnetic field in the MTJ element. A spin-injection MRAM may not include the magnetic field-generating layer. In the spin-injection MRAM, a current is allowed to flow between an upper electrode and a lower electrode in the direction perpendicular to the MTJ element (positive direction or negative direction), causing magnetization reversal (current scalability) due to electron spin torque passing through a junction surface of the MTJ element. Since the memory cell of the spin-injection MRAM does not have the magnetic-field-generating layer, the area of the memory cell may be reduced. 
         [0029]    In the memory cell of an MRAM, the area of the lower electrode may be larger than that of the upper electrode and than that of the MTJ element. A lower electrode film, an MTJ film, and an upper electrode film are sequentially formed. The upper electrode film and the MTJ film are patterned by etching to form the upper electrode and the MTJ element, and the lower electrode film is patterned to form the lower electrode. When the lower electrode film is patterned in the state that the side surface of the MTJ element is exposed, the MTJ element will be damaged by, for example, plasma in an ashing process of a resist used as a mask for the etching and may be damaged by etching gas in the etching. 
         [0030]    After patterning of the lower electrode film by etching, the resist mask used in the etching is removed by ashing to expose a surface covered by the lower electrode film and the surface of a lower layer wiring or a conductive plug. By the ashing, the conductive member such as the lower layer wiring or the conductive plug may be oxidized. 
         [0031]      FIGS. 1A to 1C ,  2 A to  2 C,  3 A to  3 D,  4 A to  4 D,  5 A to  5 D,  6 A to  6 D,  7 A to  7 C,  8 A to  8 C, and  9  illustrates an exemplary method of manufacturing an MRAM. As illustrated in  FIG. 1A , MOS transistors  20  corresponding to the selection transistors of a memory cell are formed on a silicon semiconductor substrate  10 . Element-separating structures  11  are formed on the surface layer of the silicon semiconductor substrate  10  by, for example, a shallow trench isolation process (STI process) to define an element active region. 
         [0032]    An impurity is injected into the element active region. For example, a P-type impurity is ion-injected in an N-type MOS transistor, and an N-type impurity is ion-injected in a P-type MOS transistor. For example, in an N-type transistor, boron (B) is ion-injected as a P-type impurity, for example, under conditions of a dose of 3.0×10 13 /cm 2  and an acceleration energy of 300 keV. A well  12  may be formed. 
         [0033]    In the element active region, for example, a thin gate insulating film  13  having a thickness of about 3.0 nm is formed by, for example, thermal oxidation, and, for example, a polycrystalline silicon film having a thickness of about 180 nm and a silicon nitride film having a thickness of about 29 nm are deposited on the gate insulating film  13  by a CVD process. The silicon nitride film, the polycrystalline silicon film, and the gate insulating film  13  are patterned into an electrode shape by lithography and dry etching. Thus, a gate electrode  14  is formed on the gate insulating film  13 . Contemporaneously, a cap film  15  made of the silicon nitride film may be formed on the gate electrode  14 . 
         [0034]    An impurity is injected into the element active region using the cap film  15  as a mask. For example, an N-type impurity is ion-injected for forming an N-type MOS transistor, and a P-type impurity is ion-injected for forming a P-type MOS transistor. For example, arsenic (As) is ion-injected as a P-type impurity, for example, under conditions of a dose of 5.0×10 14 /cm 2  and an acceleration energy of 10 keV. Thus, extension regions  16  are formed. 
         [0035]    For example, a silicon oxide film is deposited on the entire surface by a CVD process, and the silicon oxide film is etched back. The silicon oxide film remains on the side surfaces of the gate electrode  14  and the cap film  15  to form a side wall insulating film  17 . 
         [0036]    An impurity, for example, an N-type impurity such as P is ion-injected into the element active region using the cap film  15  and the side wall insulating film  17  as masks under conditions such that the concentration of the impurity in the element active region is higher than that in the extension region  16 . Thus, a source/drain region  18  partially superimposed on the extension region  16  is formed, and an MOS transistor  20  is formed. 
         [0037]    As illustrated in  FIG. 1B , a protective film  21  of the MOS transistors  20  and an interlayer insulating film  22  may be sequentially formed. The protective film  21  and the interlayer insulating film  22  may be sequentially formed so as to cover the MOS transistors  20 . The protective film  21  may include, for example, a silicon nitride film and be deposited by a CVD process to have a thickness of about 130 nm. The interlayer insulating film  22 , for example, a plasma TEOS film having a thickness of about 1300 nm is deposited. The surface of the interlayer insulating film  22  is planarized by polishing to have a thickness of about 700 nm by chemical mechanical polishing (CMP). 
         [0038]    As illustrated in  FIG. 1C , conductive plugs  19  to be coupled to the source/drain regions  18  of the MOS transistors  20  are formed. The interlayer insulating film  22  and the protective film  21  are patterned by lithography and dry etching using the source/drain regions  18  as an etching stopper till the surfaces of the source/drain regions  18  are each partially exposed. For example, contact-holes  19   a  each having a diameter of about 0.3 μm are formed. 
         [0039]    A base film, for example, a glue film  19   b  is formed by depositing, for example, a Ti film having a thickness of about 20 nm and a TiN film having a thickness of about 50 nm by sputtering so as to cover the inner surface of each contact-hole  19   a . Then, for example, a W film is deposited by a CVD process so as to plug the contact-hole  19   a  through the glue film  19   b . The W film and the glue film  19   b  are polished by CMP using the interlayer insulating film  22  as a polishing stopper. Thus, a conductive plug  19  that plugs the contact-hole  19   a  with W through the glue film  19   b  is formed. 
         [0040]    Wirings  25  are formed by a damascene process, for example, a single-damascene process. As illustrated in  FIG. 2A , an interlayer insulating film  23  is formed by depositing an insulating film, for example, a silicon oxide film having a thickness of about 150 nm on the interlayer insulating film  22  by, for example, a CVD process. The interlayer insulating film  23  is patterned by lithography and subsequent dry etching so that the surface of the conductive plug  19  for wiring connection is exposed to form a wiring gutter  23   a  having a wiring shape in the interlayer insulating film  23 . 
         [0041]    As illustrated in  FIG. 2B , a glue film  24  is formed by, for example, depositing a Ta film having a thickness of about 5 nm on the interlayer insulating film  23  so as to cover the inner surface of the wiring gutter  23   a  by, for example, sputtering. A plating seed layer (not shown) is formed on the glue film  24 , and the wiring gutter  23   a  is plugged with Cu (or a Cu alloy material) through the glue film  24  by plating. The Cu (or the Cu alloy material) on the interlayer insulating film  23  and the glue film  24  are polished and planarized by CMP using the interlayer insulating film  23  as a polishing stopper. By the planarization, the wiring gutter  23   a  is filled with Cu (or the Cu alloy material) to form a wiring  25  coupled to the conductive plug  19 . 
         [0042]    Wiring structures  36  are formed by a damascene process, for example, a dual-damascene process. In  FIGS. 2C and 3A  to  3 C, the interlayer insulating film  23  and portions above the interlayer insulating film  23  may be illustrated. 
         [0043]    As illustrated in  FIG. 2C , an insulating film as a diffusion-preventing film  26  for preventing diffusion of Cu (or the Cu alloy material) in the wirings  25  is formed by, for example, depositing a SiC film having a thickness of about 30 to 70 nm on the interlayer insulating film  23  by, for example, a CVD process. An interlayer insulating film  27  is formed by depositing an insulating film, for example, a SiOC film having a thickness of about 400 to 700 nm on the diffusion-preventing film  26  by, for example, a CVD process. An etching stopper film  28  is formed by depositing an insulating film, for example, a SiC film having a thickness of about 30 to 70 nm on the interlayer insulating film  27  by, for example, a CVD process. An interlayer insulating film  29  is formed by depositing an insulating film, for example, a SiOC film having a thickness of about 300 to 600 nm on the etching stopper film  28  by, for example, a CVD process. A diffusion-preventing film  31  is formed by depositing, for example, a SiC film having a thickness of 50 to 100 nm on the interlayer insulating film  29 . 
         [0044]    As illustrated in  FIG. 3A , via-holes  32  passing through the diffusion-preventing film  31 , the interlayer insulating layer  29 , the etching stopper film  28 , and the interlayer insulating film  27  are formed by lithography and dry etching, and the surface of the diffusion-preventing film  26  is exposed. A resin material layer  33  (embedded material layer) is formed on the diffusion-preventing film  31  so as to plug each via-hole  32 . The entire surface of the resin material layer  33  is dry-etched, for example, in such a manner that the resin material layer  33  with a certain thickness remains in the via-hole  32 . The thickness of the resin material layer  33  may be smaller than the thickness of the interlayer insulating film  27 . The resin material layer  33  having a certain thickness may remain in the via-hole  32  by being developed. 
         [0045]    As illustrated in  FIG. 3B , the diffusion-preventing film  31  and the interlayer insulating layer  29  are patterned by lithography and dry etching to form wiring gutters  34  having a wiring shape. The wiring gutter  34  is formed using the etching stopper film  28  as a stopper so as to be communicated with the via-hole  32  provided in the etching stopper film  28  and the interlayer insulating film  27 . The resin material layer  33  remaining in the via-hole  32  is removed by, for example, ashing. 
         [0046]    As illustrated in  FIG. 3C , a glue film  35  is formed by, for example, depositing a Ta film having a thickness of about 5 nm on the diffusion-preventing film  31  by, for example, sputtering so as to cover the inner surfaces of the via-hole  32  and the wiring gutter  34 . A plating seed layer (not illustrated) is formed on the glue film  35 , and the via-hole  32  and the wiring gutter  34  are plugged with Cu or a Cu alloy material through the glue film  35  by plating. The Cu or the Cu alloy material and the glue film  35  on the diffusion-preventing film  31  are polished and planarized by CMP using the surface of the diffusion-preventing film  31  as a polishing stopper. The insides of the via-holes  32  and the wiring gutters  34  are filled with Cu or the Cu alloy material through the glue film  35  to form wiring structures  36  electrically coupled to the wirings  25 . The insulating layer form a wiring layer  37   a  includes an insulating layer having the diffusion-preventing film  26 , the interlayer insulating film  27 , the etching stopper film  28 , the interlayer insulating layer  29 , and the diffusion-preventing film  31 , and the wiring structures  36  in the insulating layer. 
         [0047]    The dual-damascene process illustrated in  FIGS. 2C and 3A  to  3 C may be repeated a certain number of times, for example, three times. As illustrated in  FIG. 3D , three wiring layers  37   b ,  37   c , and  37   d  each having a structure that is substantially the same as or similar to that of the wiring layer  37   a  are stacked on the wiring layer  37   a  illustrated in  FIG. 3C  so as to be coupled to the wiring structures  36 . The wiring structure may be a multiple-wiring structure. 
         [0048]    As illustrated in  FIG. 4A , a lower electrode film  41 , an MTJ film  42 , and an upper electrode film  43  are sequentially formed by, for example, sputtering. In  FIGS. 4A to 4D ,  5 A to  5 D,  6 A to  6 D,  7 A to  7 C, and  8 A to  8 C, the wiring layer  37   d  and portions upper than the wiring layer  37   d  may be illustrated. 
         [0049]    For example, a Ru film and a Ta film are deposited so as to have thicknesses of about 20 nm and about 40 nm, respectively, so as to cover the wiring layer  37   d . Thus, a lower electrode film  41  is formed. On the lower electrode film  41 , for example, a PtMn film having a thickness of about 15 nm, a CoFe film having a thickness of about 3 nm, a CoFeB film having a thickness of about 2 nm, a MgO film having a thickness of about 1 nm, and a CoFeB film having a thickness of about 2 nm are deposited. The PtMn film may correspond to an antiferromagnetic layer. The CoFe film and the CoFeB film may correspond to pinned magnetic films. The MgO film may correspond to a tunnel oxide film. The CoFeB film may correspond to a free magnetic film. Thus, a magnetic film (MTJ film)  42  is formed. On the MTJ film  42 , for example, a Ru film having a thickness of about 10 nm and a Ta film having a thickness of about 50 nm are sequentially deposited. Thus, an upper electrode film  43  is formed. The lower electrode film  41 , the MTJ film  42 , and the upper electrode film  43  are formed by sputtering, for example, using Ar as the sputtering gas at a pressure of 0.5 Pa and an input power of 500 W. 
         [0050]    As illustrated in  FIG. 4B , a resist pattern  44  is formed on the upper electrode film  43 . The resist pattern  44  may be formed by, for example, applying a resist for ArF exposure on the upper electrode film  43  so as to have a thickness of about 200 nm and patterning the resist by photolithography into a shape and a size corresponding to the upper electrode. The resist pattern  44  may be a rectangular pattern, for example, with a size of about 100×150 nm. 
         [0051]    As illustrated in  FIG. 4C , the upper electrode film  43  is etched. The upper electrode film  43  may be dry-etched using the resist pattern  44  as a mask. The dry etching may etch the Ta film included in the upper electrode film  43  without etching the Ru film. The etching may be performed, for example, using a gas mixture of Cl 2  (at a flow rate of 20 sccm) and BCl 3  (at a flow rate of 60 sccm) as the etching gas at a pressure of 2 Pa and an RF input power of 500 W. 
         [0052]    As illustrated in  FIG. 4D , the resist pattern  44  is removed. The resist pattern  44  is removed by, for example, ashing using oxygen plasma. The ashing may be performed, for example, using O 2  at a flow rate of 100 scm at a pressure of 10 Pa and an RF input power of 300 W. The ashing etches by about 5 nm of the Ru film exposed in the outside of the region where the upper electrode film  43  is formed. Since the ashing is performed in the state that the MTJ film  42  is covered by the Ru film included in the upper electrode film  43 , oxidation of the MTJ film  42  due to the ashing is reduced. 
         [0053]    As illustrated in  FIG. 5A , the Ru film and the MTJ film  42  exposed in the outside of the region where the upper electrode film  43  is formed are etched. The exposed Ru film and MTJ film  42  are dry-etched using the patterned upper electrode film  43  as a mask. The dry etching may etch the Ru film and the MTJ film  42  without etching the lower electrode film  41 . The dry etching may be performed, for example, using CH 3 OH (at a flow rate of 100 sccm) as the etching gas at a pressure of 2 Pa and an RF input power of 800 W. The upper electrode film  43  is etched to form an upper electrode  43   a , and the MTJ film  42  is etched to form an MTJ  42   a . Since the etching of the Ru film and the MTJ film  42  is performed without using a resist mask, ashing of a resist after the etching may not be performed. Therefore, oxidization due to ashing may be reduced on the side surfaces of the MTJ  42   a.    
         [0054]    As illustrated in  FIG. 5B , a protective film  45   a  is formed by depositing an insulating film, for example, a SiC film having a thickness of about 20 to 60 nm on the lower electrode film  41  so as to cover the MTJ  42   a  and the upper electrode  43   a  by, for example, a CVD process. The protective film  45   a  may include, for example, SiN, SiCN, or carbon instead of SiC. 
         [0055]    As illustrated in  FIG. 5C , a resist pattern  46  is formed. The resist pattern  46  covering the MTJ  42   a  and the upper electrode  43   a  through the protective film  45   a  is formed by, for example, applying on the protective film  45   a  a trilevel resist for ArF exposure having a thickness of about 200 nm or a resist for KrF exposure having a thickness of about 500 nm and patterning the resist by photolithography into a shape and a size corresponding to a lower electrode. The resist pattern  46  may be a rectangular pattern, for example, with a size of about 200×400 nm. 
         [0056]    As illustrated in  FIG. 5D , the protective film  45   a  is etched. The protective film  45   a  may be dry-etched using the resist pattern  46  as a mask. The dry etching may etch the protective film  45   a  without etching the lower electrode film  41 . The dry etching may be performed using CF 4  (at a flow rate of 100 sccm) as the etching gas at a pressure of 5 Pa and an RF input power of 400 W. 
         [0057]    As illustrated in  FIG. 6A , the resist pattern  46  is removed. The resist pattern  46  is removed by ashing using oxygen plasma. The ashing may be performed, for example, using O 2  at a flow rate of 100 scm at a pressure of 10 Pa and an RF input power of 200 W. The ashing may be performed in the state that the side surface of the MTJ  42   a  is covered by the protective film  45   a . Therefore, oxidation of the side surface of the MTJ film  42  due to the ashing may be reduced. Since the ashing is performed in the state that the surface of the wiring structure  36  of the wiring layer  37   d  is covered by the lower electrode film  43 , oxidation due to ashing of the surface of the wiring structure  36  of the wiring layer  37   d  may be reduced. 
         [0058]    As illustrated in  FIG. 6B , the lower electrode film  41  is etched. The lower electrode film  41  may be dry-etched using the patterned protective film  45   a  as a mask. The dry etching may etch the lower electrode film  41  without etching the wiring layer  37   d , for example, the diffusion-preventing film  31 . The etching may be performed, for example, using a gas mixture of Cl 2  (at a flow rate of 20 sccm) and BCl 3  (at a flow rate of 60 sccm) as the etching gas at a pressure of 2 Pa and an RF input power of 500 W. By the etching, the lower electrode film  41  is etched to form a lower electrode  41   a , and an MTJ element  40  having the lower electrode  41   a , the MTJ  42   a , and the upper electrode  43   a  is formed. The protective film  45   a  is etched (etched back) and remains as a side wall film  45   a  covering the side surfaces of the MTJ  42   a  and the upper electrode  43   a . Since the etching of the lower electrode film  41  is performed without using a resist mask, ashing of a resist after the etching may not be performed. Therefore, oxidization due to ashing may be reduced on the surface of the wiring structure  36  of the wiring layer  37   d.    
         [0059]    As illustrated in  FIG. 6C , a protective film  45   b  is formed. The protective film  45   b  may be formed as an insulating film by, for example, depositing a SiC film having a thickness of about 15 to 50 nm, for example, a thickness of about 30 nm on the wiring layer  37   d  so as to cover the MTJ  42   a , the upper electrode  43   a , and the protective film  45   a  by, for example, a CVD process. The protective film  45   b  may include, for example, SiN, SiCN, or carbon instead of SiC. The protective films  45   a  and  45   b  may include the same material or different materials selected from SiC, SiN, SiCN, and carbon. 
         [0060]    The protective film  45   b  is stacked on the protective film  45   a , and the protective films  45   a  and  45   b  having a total thickness of about 60 nm cover the side surfaces of the MTJ  42   a  and the upper electrode  43   a . The MTJ  42   a  and the upper electrode  43   a  are covered by the protective film  45   b  at regions other than the side surfaces. Since the side surface of the MTJ  42   a  is covered by the protective films  45   a  and  45   b , process damage to the MTJ  42   a  may be reduced. The regions other than the side surface, such as the upper surface of the upper electrode  43   a , are covered by the protective film  45   b  for providing conduction to the upper electrode  43   a . For example, the upper surface of the upper electrode  43   a  may be exposed by, for example, etching. The protective film  45   b  may reduce diffusion of Cu in the wiring structure  36  of the wiring layer  37   d.    
         [0061]    As illustrated in  FIG. 6D , an interlayer insulating film  47  is formed. The interlayer insulating film  47  is formed by, for example, forming a SiOC film having a thickness of about 100 to 500 nm, for example, a thickness of about 250 nm so as to cover the protective film  45   b  by, for example, a CVD or application process. The interlayer insulating film  47  may include, for example, a low-dielectric film (low-k film) or SiO 2  instead of SiOC. 
         [0062]    As illustrated in  FIG. 7A , the surface of the interlayer insulating film  47  is planarized, and a diffusion-preventing film  48  is formed thereon. The interlayer insulating film  47  is planarized by polishing its surface layer by CMP. An insulating film as the diffusion-preventing film  48 , for example, a SiC film having a thickness of about 30 to 70 nm, for example, a thickness of about 30 nm is deposited on the interlayer insulating film  47  having the planarized surface. The diffusion-preventing film  48  may reduce diffusion of Cu in the wiring structure. 
         [0063]    The wiring structure and the wiring are formed by a damascene process, for example, a dual-damascene process. As illustrated in  FIG. 7B , in the wiring structure  36  not being provided with the lower electrode  41   a  on the upper portion of the wiring layer  37   d , the diffusion-preventing film  48  and the interlayer insulating film  47  are patterned by lithography and dry etching. The diffusion-preventing film  48  and the interlayer insulating film  47  are etched using the protective film  45   b  as an etching stopper till the surface of the protective film  45   b  on the wiring structure  36  is partially exposed. A via-hole  49  passing through the diffusion-preventing film  48  and the interlayer insulating film  47  is formed. A resin material layer  51  (embedded material layer) is formed on the diffusion-preventing film  48  to plug the via-hole  49 . The resin material layer  51  is dry-etched in such a manner that the resin material layer  51  with a certain thickness remains in the via-hole  49 . 
         [0064]    As illustrated in  FIG. 7C , a resist pattern  52  is formed by applying a resist on the diffusion-preventing film  48  and patterning the resist by lithography. In the resist pattern  52 , an opening  52   a  having a wiring shape is formed at a position where the via-hole  49  is formed on the diffusion-preventing film  48  and an opening  52   b  having a wiring shape is formed at a position corresponding to the upper position of the upper electrode  43   a.    
         [0065]    As illustrated in  FIG. 8A , the diffusion-preventing film  48  and the interlayer insulating film  47  are dry-etched till the surface of the protective film  45   b  is partially exposed using the resist pattern  52  as a mask and the protective film  45   b  on the upper electrode  43   a  as an etching stopper. The etching gas for the dry etching may be, for example, CF 4 . A wiring gutter  53   a  communicating with the via-hole  49  and a wiring gutter  53   b  having a bottom on which a portion of the surface of the protective film  45   b  on the upper electrode  43   a  is exposed may be contemporaneously formed. The resist pattern  52  and the resin material layer  51  remaining in the via-hole  49  are removed by ashing. Since the ashing is performed in the state that the upper surface of the upper electrode  43   a  is covered by the protective film  45   b , oxidation of the upper electrode  43   a  due to the ashing may be reduced. 
         [0066]    As illustrated in  FIG. 8B , the protective film  45   b  exposed at the bottom surface of the via-hole  49  and the protective film  45   b  exposed at the bottom surface of the wiring gutter  53   b  are dry-etched using the diffusion-preventing film  48  as a mask. The etching gas for the dry etching may be, for example, a gas mixture of CH 2 F 2 , O 2 , and N 2 . The surface of the wiring structure  36  of the wiring layer  37   d  is partially exposed at the bottom surface of the via-hole  49 , and the surface of the upper electrode  43   a  is partially exposed at the bottom surface of the wiring gutter  53   b . Since the etching of the protective film  45   b  is performed without using a resist mask, ashing of a resist after the etching may not be performed. Therefore, no oxidization due to ashing occurs in the upper electrode  43   a . The protective film  45   b  on the upper electrode  43   a  may be etched using the diffusion-preventing film  48  as a mask. 
         [0067]    As illustrated in  FIG. 8C , a glue film  54  is formed by, for example, depositing a Ta film having a thickness of about 5 nm on the diffusion-preventing film  48  by, for example, sputtering so as to cover the inner surface of the unified via-hole  49  and the wiring gutter  53   a  and the inner surface of the wiring gutter  53   b . A plating seed layer (not illustrated) is formed on the glue film  54 , and the via-hole  49  and the wiring gutter  53   a  and the wiring gutter  53   b  are plugged with Cu or a Cu alloy material through the glue film  54  by plating. The Cu or the Cu alloy material on the diffusion-preventing film  48  and the glue film  54  are polished and planarized by CMP using the surface of the diffusion-preventing film  48  as a polishing stopper. The via-hole  49  and the wiring gutter  53   a  are filled with Cu or the Cu alloy material through the glue film  54  by the planarization to form a wiring structure  55  being electrically coupled with the wiring structure  36 . The wiring gutter  53   b  may be contemporaneously filled with Cu or the Cu alloy material through the glue film  54  to form a wiring  56  being electrically coupled with the upper electrode  43   a . The wiring layer  57  may include an insulating layer having the protective films  45   a  and  45   b , the interlayer insulating film  47 , and the diffusion-preventing film  48  and include a structure having the MTJ element  40  formed in the insulating layer, the wiring structure  55 , and the wiring  56 . 
         [0068]    In the wiring layer  57 , the MTJ element  40  may be coupled to the wiring  56  without through the via-hole portion. The wiring structure  55  and the wiring  56  may be contemporaneously formed in one process, thereby reducing a number of manufacturing processes. 
         [0069]    As illustrated in  FIG. 9 , by the dual-damascene process illustrated in  FIGS. 2C and 3A  to  3 C, a wiring layer  37   e , having a structure that is substantially the same as those of the wiring layers  37   a  to  37   d  and having a wiring structure  36  that is electrically coupled with at least one of the wiring structure  55  and the wiring  56  on the wiring layer  57 , is formed. 
         [0070]    An upper wiring layer, a protective film, and a pad electrode are formed, and thereby an MRAM is formed. 
         [0071]      FIG. 10  illustrates an exemplary MRAM. As illustrated in  FIG. 10 , the MTJ element  40  is coupled to the wiring  56  without passing through the via-hole portion in the wiring layer  57 . The upper surface of the MTJ element  40  and the upper surface of the via-hole portion  55   a  of the wiring structure  55  are substantially the same level, and the upper surface of the wiring  56  and the upper surface of the wiring gutter portion  55   b  of the wiring structure  55  are substantially the same level. The thickness “A” of the lower electrode  41   a  of the MTJ element  40 , the thickness “B” of the MTJ  42   a , the thickness “C” of the upper electrode film  43  before patterning, the thickness “C′” of the upper electrode  43   a  considering the selection ratio in etching of the Ru film of the upper electrode film  43  and the MTJ film  42 , and the height (thickness) “D” of the via-hole portion  55   a  of the wiring structure  55  satisfy the following relational expression: 
         [0000]    
       
      
       D=A+B+C′ 
      
     
         [0072]    Since the thickness of the MTJ  42   a  is about 20 to 30 nm, the thickness “A” of the lower electrode  41   a  and the thickness “C′” of the upper electrode film  43  when they are formed are determined so as to satisfy the relational expression. 
         [0073]    Damage to the MTJ element  40  when the MRAM having the MTJ element  40  is manufactured may be reduced. Since ashing is not performed when the lower electrode film  41  is patterned, oxidation of the wiring structures  36  lying under the lower electrode film  41 , which include the conductive member, may be reduced. As a result, an MRAM having high reliability may be provided. 
         [0074]    Via-holes may be formed in the upper electrode  43   a.    
         [0075]      FIGS. 11A to 11C  illustrate an exemplary method of manufacturing an MRAM. In  FIGS. 11A and 11C , substantially the same elements as those of  FIGS. 1A to 1C ,  2 A to  2 C,  3 A to  3 D,  4 A to  4 D,  5 A to  5 D,  6 A to  6 D,  7 A to  7 C,  8 A to  8 C,  9 , and  10  are given the same reference numerals, and descriptions thereof may be omitted or reduced. As illustrated in  FIG. 11A , a resist pattern  61  is formed by applying a resist on the diffusion-preventing film  48  and patterning the resist by lithography. The resist pattern  61  is provided with an opening  61   a  at the position corresponding to the wiring structure  36  not having the lower electrode  41   a  in the wiring layer  37   d  and an opening  61   b  having a wiring shape at the position corresponding to the upper electrode  43   a.    
         [0076]    As illustrated in  FIG. 11B , the diffusion-preventing film  48  and the interlayer insulating film  47  are dry-etched till the surface of the protective film  45   b  is partially exposed using the resist pattern  61  as a mask and the protective film  45   b  as an etching stopper. The etching gas for the dry etching may be, for example, CF 4 . A via-hole  62   a  is formed so that the surface of the protective film  45   b  on the wiring structure  36  is exposed, and a via-hole  62   b  is formed so that the surface of the protective film  45   b  on the upper electrode  43   a  is exposed. The resist pattern  61  is removed by ashing. Since the ashing is performed in the state that the upper surface of the upper electrode  43   a  is covered by the protective film  45   b , oxidation due to ashing of the upper electrode  43   a  may be reduced. 
         [0077]    As illustrated in  FIG. 11C , the protective film  45   b  exposed at the bottom surfaces of the via-holes  62   a  and  62   b  is dry-etched using the diffusion-preventing film  48  as a mask. The surface of the wiring structure  36  is partially exposed at the bottom surface of the via-hole  62   a , and the surface of the upper electrode  43   a  is partially exposed at the bottom surface of the via-hole  62   b . Since the protective film  45   b  is etched without using a resist mask, ashing of a resist after the etching may not be performed. Therefore, oxidization due to ashing may not occur in the upper electrode  43   a . Since the protective film  45   b  on the upper electrode  43   a  is thin, the protective film  45   b  may be etched using the diffusion-preventing film  48  as a mask. 
         [0078]    For example, the via-holes  62   a  and  62   b  are each filled with, for example, W through a glue film to form conductive plugs, and wirings coupled to the corresponding conductive plugs are formed by a single damascene process. An upper wiring layer, a protective film, and a pad electrode are formed, and then an MRAM is formed. 
         [0079]    Damage to the MTJ element  40  when the MRAM having the MTJ element  40  is manufactured may be reduced. Since ashing is not performed when the lower electrode film  41   a  is patterned, oxidation of the wiring structures  36  lying under the lower electrode film  41   a , which include the conductive member, may be reduced. As a result, an MRAM having high reliability may be provided. 
         [0080]      FIGS. 12A and 12B  illustrate an exemplary MRAM. As illustrated in  FIG. 12A , the wiring structure  36  of the wiring layer  37   d , which is coupled to the lower surface of the lower electrode  41   a , and the MTJ  42   a  and the upper electrode  43   a  of the MTJ element  40 , which are coupled to the upper surface of the lower electrode  41   a , may be formed not to overlap in a plan view. The upper portion of the wiring structure  36  may not be planarized on the lower electrode  41   a . When the MTJ  42   a  and the upper electrode  43   a  are formed on the lower electrode  41   a , the element performance of the MTJ element  40  may be decreased. Accordingly, the MTJ  42   a  and the upper electrode  43   a  may be formed on the planarized portion on the lower electrode  41   a  so as not to overlap the wiring structures  36  in a plan view. As a result, the MTJ element  40  may have high performance. 
         [0081]    As illustrated in  FIG. 12B , the wiring structure  36  and the MTJ  42   a /the upper electrode  43   a , which are respectively coupled to the lower surface and the upper surface of the lower electrode  41   a , may be formed to be parallel to each other in the longitudinal direction. In such a case, the MTJ  42   a  and the upper electrode  43   a  are formed on the planarized lower electrode  41   a  so as not to overlap the wiring structure  36  in a plan view. The area of the lower electrode  41   a  may be reduced. 
         [0082]    Damage to the MTJ element  40  when the MRAM having the MTJ element  40  is manufactured may be reduced. Since ashing is not performed when the lower electrode film  41   a  is patterned, oxidation of the wiring structure  36  lying under the lower electrode film  41   a , which includes the conductive member, may not occur. As a result, an MRAM having high reliability may be provided. 
         [0083]      FIGS. 13A to 13C ,  14 A to  14 C,  15 A to  15 C,  16 A to  16 C,  17 A to  17 C,  18 A to  18 C, and  19  illustrate an exemplary a method of manufacturing an MRAM. In these figures, substantially the same elements as those of  FIGS. 1A to 1C ,  2 A to  2 C,  3 A to  3 D,  4 A to  4 D,  5 A to  5 D,  6 A to  6 D,  7 A to  7 C,  8 A to  8 C,  9 ,  10 ,  11 A to  11 C,  12 A, and  12 B are given the same reference numerals, and descriptions thereof may be omitted or reduced. As illustrated in  FIG. 13A , a lower electrode film  41 , an MTJ film  42 , and an upper electrode film  43  are formed as in  FIG. 4A . 
         [0084]    As illustrated in  FIG. 13B , a resist pattern  44  is formed on the upper electrode film  43  as in  FIG. 4B . As illustrated in  FIG. 13C , the upper electrode film  43  is etched as in  FIG. 4C . 
         [0085]    As illustrated in  FIG. 14A , the resist pattern  44  is removed as in  FIG. 4D . Since the ashing is performed in the state where the MTJ film  42  is covered by the Ru film contained in the upper electrode film  43 , oxidation of the MTJ film  42  may be reduced. 
         [0086]    As illustrated in  FIG. 14B , the Ru film and the MTJ film  42  exposed in the outside of the region where the upper electrode film  43  is formed are etched as in  FIG. 5A . Since the Ru film and the MTJ film  42  are dry-etched without using a mask, ashing is not performed after the etching. Therefore, oxidation due to ashing of the side surface of the MTJ  42   a  may not occur. 
         [0087]    As illustrated in  FIG. 14C , a protective film  45   a  is formed as in  FIG. 5B . As illustrated in  FIG. 15A , a resist pattern  46  is formed as in  FIG. 5C . As illustrated in  FIG. 15B , the protective film  45   a  is etched as in  FIG. 5D . 
         [0088]    As illustrated in  FIG. 15C , the resist pattern  46  is removed as in  FIG. 6A . Since the ashing is performed in the state where the side surface of the MTJ  42   a  is covered by the protective film  45   a , oxidation due to ashing of the side surface of the MTJ film  42  may be reduced. Since the ashing is performed in the state where the surface of the conductive plug  19  formed in the interlayer insulating film  22  is covered by the lower electrode film  43 , oxidation of the surface of the conductive plug  19  may be reduced. 
         [0089]    As illustrated in  FIG. 16A , the lower electrode film  41  is etched as in  FIG. 6B . Since the lower electrode film  41  is etched without using a resist mask, ashing of a resist is not performed after the etching. Therefore, oxidation due to ashing of the surface of the conductive plug  19  formed in the interlayer insulating film  22  may not occur. 
         [0090]    As illustrated in  FIG. 16B , a protective film  45   b  is formed as in  FIG. 6C . The side surfaces of the MTJ  42   a  and the upper electrode  43   a  are covered by the stacked protective films  45   a  and  45   b  having a total thickness of about 60 nm. The MTJ  42   a  and the upper electrode  43   a  may be covered by the protective film  45   b  at regions other than the side surfaces. Since the side surface of the MTJ  42   a  is covered by the protective films  45   a  and  45   b , process damage to the MTJ  42   a  may be reduced. The regions other than the side surfaces such as the upper surface of the upper electrode  43   a  covered by the protective film  45   b  may be exposed by subsequent etching. 
         [0091]    As illustrated in  FIG. 16C , an interlayer insulating film  47  is formed as in  FIG. 6D . As illustrated in  FIG. 17A , the surface of the interlayer insulating film  47  is planarized, and the diffusion-preventing film  48  is formed thereon, as in  FIG. 7A . 
         [0092]    As illustrated in  FIG. 17B , the diffusion-preventing film  48  and the interlayer insulating film  47  are patterned by lithography and dry etching, as in  FIG. 7B , to form via-holes  49  above the conductive plugs not being provided with the lower electrode  41   a  on the upper portion. A resin material layer  51  is formed on the diffusion-preventing film  48  so as to plug the via-holes  49 . The resin material layer  51  may be dry-etched so that the resin material layer  51  with a certain thickness remains in each via-hole  49 . 
         [0093]    As illustrated in  FIG. 17C , a resist pattern  52  is formed on the diffusion-preventing film  48  as in  FIG. 7C . As illustrated in  FIG. 18A , the diffusion-preventing film  48  and the interlayer insulating film  47  are dry-etched using the resist pattern  52  as a mask as in  FIG. 8A . The dry etching may be performed till the surface of the protective film  45   b  is partially exposed using the protective film  45   b  on the upper electrode  43   a  as an etching stopper. The wiring gutters  53   a  communicating with the via-holes  49  and the wiring gutter  53   b  having the bottom surface where the surface of the protective film  45   b  on the upper electrode  43   a  is partially exposed may be substantially contemporaneously formed. The resist pattern  52  and the resin material layer  51  remaining in the via-hole  49  are removed by ashing. Since the resist pattern  52  and the resin material layer  51  are ashed in the state where the upper surface of the upper electrode  43   a  is covered by the protective film  45   b , oxidation due to ashing of the upper electrode  43   a  may be reduced. 
         [0094]    As illustrated in  FIG. 18B , the protective film  45   b  exposed at the bottom surface of the via-hole  49  and the protective film  45   b  exposed at the bottom surface of the wiring gutter  53   b  are dry-etched using the diffusion-preventing film  48  as a mask as in  FIG. 8B . The surface of the conductive plug  19  is partially exposed at the bottom surface of the via-hole  49 , and the surface of the upper electrode  43   a  is partially exposed at the bottom surface of the wiring gutter  53   b . Since the protective film  45   b  is etched without using a resist mask, ashing of a resist after the etching may not be conducted. Therefore, oxidation due to ashing may not occur in the upper electrode  43   a . Since the upper electrode  43   a  is covered by the protective film  45   b , the upper electrode  43   a  is etched using the diffusion-preventing film  48  as a mask. 
         [0095]    As illustrated in  FIG. 18C , a glue film  54  is formed so as to cover the inner surfaces of the unified via-hole  49  and the wiring gutter  53   a  and the inner surface of the wiring gutter  53   b , as in  FIG. 8C . A plating seed layer (not shown) is formed on the glue film  54 , and the via-holes  49  and the wiring gutters  53   a  and the wiring gutter  53   b  are plugged with Cu or a Cu alloy material by plating through the glue film  54 . The Cu or the Cu alloy material on the diffusion-preventing film  48  and the glue film  54  are polished and planarized by CMP using the surface of the diffusion-preventing film  48  as a polishing stopper. The via-hole  49  and the wiring gutter  53   a  are filled with Cu or the Cu alloy material through the glue films  54  to form a wiring structure  55  being electrically coupled to the conductive plug  19 . The wiring gutter  53   b  is filled with Cu or the Cu alloy material through the glue film  54  to form a wiring  56  being electrically coupled to the upper electrode  43   a . The wiring structures  55  and the wiring  56  may be substantially contemporaneously formed. The protective films  45   a  and  45   b , the interlayer insulating film  47 , and the diffusion-preventing film  48  form an insulating layer. The wiring layer  57  may include the insulating layer and a structure having the MTJ element  40  formed in the insulating layer, the wiring structures  55  and the wiring  56 . 
         [0096]    As illustrated in  FIG. 19 , a dual-damascene process substantially the same as or similar to that illustrated in  FIGS. 2C and 3A  to  3 C is repeated a plurality of times, for example, four times. The wiring layers  63   a  to  63   d  each having a structure that is substantially the same as or similar to that of the wiring layer  37   a  where the wiring structures  55  and the wiring  56  are electrically coupled to each other may be sequentially formed on the wiring layer  57 . 
         [0097]    An upper wiring layer, a protective film, and a pad electrode are formed, and then an MRAM is formed. 
         [0098]    Damage to the MTJ element  40  when the MRAM having the MTJ element  40  is manufactured may be reduced. Since ashing is not performed in the patterning of the lower electrode film  41 , the conductive member of the layer lying under the lower electrode film  41 , for example, the conductive plug  19  including W, may not be oxidized. Therefore, an MRAM having high reliability may be provided. 
         [0099]    Example embodiments of the present invention have now been described in accordance with the above advantages. It will be appreciated that these examples are merely illustrative of the invention. Many variations and modifications will be apparent to those skilled in the art.

Technology Category: 5