Patent Publication Number: US-7911741-B2

Title: Slider overcoat for noise reduction of TMR magnetic transducer

Description:
RELATED APPLICATIONS 
     This application is related to U.S. patent application Ser. No. 11/799,235, entitled “PROCESS METHODS FOR NOISE REDUCTION OF TMR MAGNETIC TRANSDUCER” by Peter Dang, et al, filed Apr. 30, 2007, assigned to the assignee of the present invention. 
     TECHNICAL FIELD 
     This invention relates generally to the field of direct access storage devices and in particular to the fabrication and performance of TMR magnetic recording transducers. 
     BACKGROUND ART 
     Direct access storage devices (DASD) have become part of every day life, and as such, expectations and demands continually increase for better performance at lower cost. To meet these demands, the mechano-electrical assembly in a DASD device, specifically the Hard Disk Drive (HDD) has evolved to meet these demands. 
     In order for an HDD to hold more data, advances in the disk media in which the data is written as well as the magnetic transducer for writing and reading the data have undergone major advances in the past few years. 
     The magnetic transducer used in the first hard disk drives was based on an inductive principle for both writing and reading data to and from the disk media. For writing data into the disk media, electric current is passed through an electrically conductive coil, which is wrapped around a ferromagnetic core. The electric current passing through the write coil induces a magnetic field in the core, which magnetizes a pattern of localized spots in the disk media as the disk media passes close to the magnetic transducer. The pattern of magnetized spots in the media forms data that can be read and manipulated by the HDD. To read this data, the disk passes the magnetized spots of written data close to the same magnetic core used for writing the data. The magnetized spots passing close to the ferromagnetic core induce a magnetic field in the core. The magnetic field induced in the ferromagnetic core induces an electric current in a read coil similar to the write coil. The HDD interprets the induced electric current from the read coil as data. 
     Magnetoresistance (MR) transducers replaced inductive read heads. An MR transducer reads written data in disk media, still in the form of magnetized spots, by sensing the change in electrical resistance of a magneto-resistive element in the MR transducer. An electric current is passed through an MR transducer. The current typically traverses the MR transducer perpendicularly to the direction of disk rotation. 
     Advances in the magneto-resistive element materials have made the MR transducer more sensitive and is now referred to as a giant magnetoresistance (GMR) transducer. As with the MR transducer, the current typically traverses the GMR transducer perpendicularly to the direction of disk rotation, and the data is written in the disk media with an inductive write transducer. 
     Further advances in magneto-resistive reading have given rise to tunneling magnetoresistance (TMR) magnetic transducers. The current traversing the TMR magnetic transducer is typically parallel to the direction of disk rotation. A thin insulator barrier is placed between two ferromagnetic conductors. Electrons tunnel through the thin insulator barrier. The resistance of the electrons tunneling through the thin insulator barrier will change as the magnetic domain structure within the two ferromagnetic conductors react to the presence of a magnetized spot in the disk media. In this manner, data can be read that has been magnetically written in the disk media. 
     Continuing advances are being made in the TMR magnetic transducer design and fabrication methods as more demands are made on the performance of HDDs using TMR magnetic transducers. 
     SUMMARY OF THE INVENTION 
     Various embodiments of the present invention are described herein. A hard disk drive slider comprises an overcoat layer, which covers an air-bearing surface of the slider. The overcoat covers an exposed surface of a tunneling magnetoresistance transducer. An adhesion layer is coupled with the overcoat layer and the air-bearing surface. The adhesion layer comprises a compound of nitrogen. The compound of nitrogen reduces noise in read data from the tunneling magnetoresistance transducer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention: 
         FIG. 1  is an isometric blow-apart of an HDD in accordance with one embodiment of the present invention. 
         FIG. 2  is an isometric detail of an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 3  is a cross-section of an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 4  is a cross-section of a detail of an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 5  is a cross-section of a detail of an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 6  is an isometric view of a TMR transducer of an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 7  is an isometric view of a repaired TMR transducer of an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 8  is a cross-section of a TMR transducer of an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 9  is a flow chart illustrating steps of a fabrication process for an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 10(   a - c ) are cross-sections of a detail of an HDD slider at process steps of fabrication in accordance with one embodiment of the present invention. 
         FIG. 11  is a flow chart illustrating steps of a fabrication process for an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 12(   a - d)  are cross-sections of a detail of an HDD slider at process steps of fabrication in accordance with one embodiment of the present invention. 
         FIG. 13  is a flow chart illustrating steps of a repair and fabrication process for an HDD slider in accordance with one embodiment of the present invention. 
         FIG. 14(   a - d ) are cross-sections of a detail of an HDD slider at process steps of repair and fabrication in accordance with one embodiment of the present invention. 
         FIG. 15  is a flow chart illustrating steps of a fabrication process for a TMR transducer in accordance with one embodiment of the present invention. 
         FIG. 16(   a - c ) are cross-sections of a detail of a TMR transducer at process steps of fabrication in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the alternative embodiment(s) of the present invention. While the invention will be described in conjunction with the alternative embodiment(s), it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which maybe included within the spirit and scope of the invention as defined by the appended claims. 
     Furthermore, in the following detailed description of embodiments of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that embodiments of the present invention may be practiced without these specific details. In other instances, well known methods, procedures, and components have not been described in detail as not to unnecessarily obscure aspects of the present invention. 
     The discussion will begin with a brief overview of a TMR magnetic transducer used in an HDD and the newly discovered effects that an overcoat process and trimming processes during fabrication have on the performance of a TMR magnetic transducer. The discussion will then focus on embodiments of the present invention that solve deleterious effects that the overcoat and trimming processes have on the TMR magnetic transducer performance. The implementation of embodiments of the present invention will then be discussed. 
     Overview 
     With reference to  FIG. 1 , an isometric blow-apart of HDD  100  is shown in accordance with an embodiment of this invention. Base casting  113  provides coupling points for components and sub-assemblies such as disk stack  158 , voice coil motor (VCM)  142 , and actuator assembly  120 . Disk stack  158  is coupled to base casting  113  by means of motor-hub assembly  140 . Motor-hub assembly  140  will have at least one disk  157  coupled to it whereby disk  157  can rotate about an axis common to motor-hub assembly  140  and the center of disk  157 . Disk  157  has at least one surface  130  upon which reside data tracks  135 . Actuator assembly  120  comprises in part suspension  127 , which suspends hard disk drive slider  125  next to disk surface  130 , and connector  117 , which conveys data between arm electronics (A/E)  115  and a host system wherein HDD  100  resides. Flex cable  110 , which is part of actuator assembly  120 , conveys data between connector  117  and A/E  115 . 
     Actuator assembly  120  is coupled pivotally to base casting  113  by means of pivot bearing  145 , whereby VCM  142  can move HDD slider  125  arcuately across data tracks  135 . Upon assembly of actuator assembly  120 , disk stack  158 , VCM  142 , and other components with base casting  113 , cover  112  is coupled to base casting  113  to enclose these components and sub-assemblies into HDD  100 . 
     With reference to  FIG. 2 , an isometric detail  200  of HGA  260  is presented in accordance with an embodiment of the present invention. Detail  200  is the most distal end of HGA  260  comprising suspension  127  and HDD slider  125 . Slider  125  comprises magnetic transducer  225 , which writes and reads data tracks  135  onto disk surface  130 , and air-bearing surface (ABS)  220 , which in cooperation with suspension  127  provides a proper balance of forces, whereby magnetic transducer  225  is closely spaced from disk surface  130  by a film of air. 
     With reference now to  FIG. 2  and  FIG. 3 , section line  210  and cross-section  300  bisects magnetic transducer  225  and reveals in cross-section inductive write transducer  345  and TMR magnetic read transducer  335 . TMR transducer  335  and inductive write transducer  345  are exposed at ABS  220 . Cross-section  300  of slider  125  is presented in accordance with one embodiment of the present invention. Cross-section  300  is not to scale. Feature sizes are exaggerated to facilitate their presentation. 
     ABS  220  includes exposed surfaces of magnetic transducer  225 . Magnetic transducer  225  comprises inductive write transducer  345  and TMR magnetic read transducer  335 . The exposed surfaces of magnetic transducer  225  are typically at a location on ABS  220  that is positioned closest to disk surface  130 . Occasionally ABS  220  may contact disk surface  130  and possibly damage magnetic transducer  225 . To prevent such damage, a protective covering known as overcoat  325  is applied to ABS  220 . 
     Overcoat  325  can be made with various types of carbon layers known to those skilled in the art, such as Filtered Cathodic Arc Carbon (FCAC) and Diamond-Like Carbon (DLC). The scope of the embodiment of the present invention is not limited to FCAC and DLC. FCAC and DLC are presented only as examples of carbon layers used in the art of fabricating an overcoat. The scope of the embodiment of the present invention includes in the overcoat, any layer typically applied to ABS  220 . This includes but is not limited to adhesion layer  323  and/or carbon layer  324 . 
     Physical Description 
     With reference to  FIG. 4 , detail  400  of cross-section  300  of slider  125 , is presented in accordance with an embodiment of the present invention. Detail  400  is a detail of TMR transducer  335 . TMR transducer  335  comprises first ferromagnetic lead  410 , TMR stack  412 , and second ferromagnetic lead  420 . Typically first and second ferromagnetic leads ( 410 ,  420 ) comprise cobalt-iron (CoFe). The embodiment of the present invention is not dependent upon the use of CoFe in the ferromagnetic leads. CoFe is only presented as an example of a ferromagnetic material. Another example of a typical ferromagnetic material used in a TMR magnetic transducer is nickel-iron (NiFe). In general, the ferromagnetic material used in a TMR magnetic transducer typical comprises a compound of iron (Fe). 
     Carbon layer  324  is expected to adhere to a variety of materials comprising ABS  220 , e.g. slider body  315 , which is typically an amalgam of alumina and titanium carbide, ferromagnetic leads ( 410 ,  420 ), TMR stack  412 , and various metal compounds and ceramics comprising magnetic transducer  225 , which comprise ABS  220 . To enhance the adhesion of carbon layer  324  to ABS  220 , adhesion layer  323  is typically coupled to carbon layer  324  and ABS  220 . Adhesion layer  323  is typically a layer of silicon (Si). 
     TMR stack  412  is fabricated with a variety of layers. TMR stack  412  typically comprises an insulator barrier  415  of magnesium-oxide (MgO), titanium-oxide (TiO 2 ), or alumina (Al 2 O 3 ). The insulating barrier material is approximately stoichiometric and is fabricated to thickness  417  that is approximately 10 Å. The scope of the embodiment of the present invention is not limited by material used for insulator barrier  415 . MgO, TiO 2 , and Al 2 O 3  are presented only as examples of compounds that may comprise insulator barrier  415  in TMR magnetic transducer  335 . In general, the insulator barrier material in a TMR stack used in a TMR magnetic transducer typical comprises a compound of oxygen (O). 
     In operation, electric current  450  is applied between first and second ferromagnetic leads ( 410 ,  420 ). By virtue of thickness  417  being sufficiently small, electrons  455  can tunnel through insulator barrier  415  and between first and second ferromagnetic leads ( 410 ,  420 ). The ability of electric current  450  to flow between first and second ferromagnetic leads ( 410 ,  420 ) can be measured as electrical resistance. Electrical resistance will change when TMR magnetic transducer  335  is adjacent to a magnetic field, such as that present in magnetic data encoded in data tracks  135  ( FIG. 1 ). 
     Ideally the electrical resistance measured from TMR magnetic transducer  335  changes only in the presence of a magnetic field. In reality, there are variations in electrical resistance that can occur in an uncontrolled manner. These variations are typically referred to as read-back signal noise. The sources and causes of noise are varied. Noise in an individual TMR transducer can make its performance unreliable. Noise that varies between groups of TMR transducers can make supporting electronics such as A/E  115  ( FIG. 1 ) non-functional for some TMR transducers. 
     A recent discovery has found that a cause for this read-back signal noise is due to damage inflicted upon TMR stack  412  such as oxygen atoms being dislodged from insulator barrier  415  and causing oxygen vacancy  465 . As electric current  450  is applied between first and second ferromagnetic leads ( 410 ,  420 ), oxygen vacancy  465  may trap electrons  455  and inhibit their ability to tunnel through insulator barrier  415 . It has also been discovered that a cleaning process performed just prior to the application of adhesion layer  323  can cause damage to TMR stack  412 . The cleaning process prior to application of adhesion layer  323  is typically a sputter etch process, well known in the art. It has been discovered that the sputter etch process causes damage to TMR stack  412  such as dislodging oxygen from the oxygen compound in insulator barrier  415 . Oxygen vacancy  465  typically occur closest to ABS  220 , since this is the surface that receives the sputter etch process prior to the application of adhesion layer  323 . 
     One possible approach to eliminating oxygen vacancy  465  is to introduce oxygen into oxygen vacancy  465 . A possible deleterious result of introducing oxygen is the oxidation (corrosion) of first and second ferromagnetic leads ( 410 ,  420 ), which typically comprise a compound of Fe such as CoFe or NiFe. It is well known in the art that Fe is readily oxidized in the presence of oxygen. For this reason it is customary practice in the art to be cautious with compounds or atmospheres containing oxygen that may come into contact with an unprotected ferromagnetic compound. 
     In accordance with one embodiment of the present invention, oxygen vacancy  465  is filled with nitrogen. A recent discovery has found that MgO absorbs nitrogen (N) in TMR stack  412  that has been damaged such as when oxygen vacancy  465  exists. Although there is a preferential absorption of oxygen by MgO, nitrogen will also be absorbed by MgO. 
     With reference to  FIG. 5 , detail  500  of cross-section  300  of slider  125 , is presented in accordance with an embodiment of the present invention. Detail  500  is a detail of TMR transducer  535 , which has reduced read-back signal noise due to damage to TMR stack  512 . Nitrogen atoms from adhesion layer  523  repair damaged TMR stack  512 , for example by filling oxygen vacancy  565  in insulator barrier  515  with nitrogen atoms from adhesion layer  523  Approximately stoichiometric SiN x  is typically a stable compound. By adhesion layer  323  comprising SiN x , Si is bound to N, and is prevented from grabbing oxygen atoms from insulator barrier  515 . 
     As electric current  550  is applied between first ferromagnetic lead  510  and second ferromagnetic lead  520 , nitrogen filled oxygen vacancy  565  cannot trap electrons  555  and thus reduces the variations in resistance of current  550  and thereby reduces read-back signal noise from TMR transducer  535 . 
     The term “x” in SiN x  is the number of nitrogen atoms bound to silicon atoms to form a compound of nitrogen and silicon. The effective range of “x” to fill oxygen vacancy  565  with nitrogen is 1.03 to 1.63. The preferred range of “x” to fill oxygen vacancy  565  with nitrogen is 1.11 to 1.43. The resulting compound of silicon and nitrogen is approximately stoichiometric silicon-nitride, Si 3 N 4 . 
     It has also been discovered that a source of nitrogen atoms for filling oxygen vacancies can also be an atmosphere of gas or an atmosphere of plasma. In accordance with another embodiment of the present invention, the source of nitrogen for filling oxygen vacancies is an atmosphere comprising nitrogen, such as an atmosphere of nitrogen gas, nitric oxide gas, nitrogen plasma, or nitric oxide plasma. The atmosphere comprising nitrogen is back-filled into a sputtering chamber prior to the deposition of an adhesion layer. In accordance with an embodiment of the present invention, the adhesion layer is not required to comprise a compound of nitrogen in order to fill oxygen vacancies, since the atmosphere comprising nitrogen is the source of nitrogen. The adhesion layer may comprise a compound such as Si or SiO 2 . By exposing an insulator barrier that has been damaged, the TMR transducer previously described in HDD slider  125  may be repaired, and thus reduce read-back signal noise from the TMR transducer. 
     Possible damage to TMR stack  412  is not restricted to the overcoat process. Any process during the fabrication of TMR magnetic transducer  335 , which exposes TMR stack  412  to a ionizing process such as sputter etching, ion milling, or reactive ion etching (RIE), can possibly damage TMR stack  412 , such as creating oxygen vacancy  465 . 
     With reference to  FIG. 6 , an isometric view of TMR transducer  635  of HDD slider  125  is presented in accordance with an embodiment of the present invention. First ferromagnetic lead  410  is deposited on the surface of slider body  315 . TMR stack  612  is deposited on to first ferromagnetic lead  410  TMR stack  612  is trimmed by means of plasma  625 . Examples of plasma known in the art are ion milling or reactive ion etching (RIE). Exposing TMR stack  612  to plasma may damage TMR stack  615  and cause variations in resistance through TMR stack  615 , resulting in read-back signal noise from TMR transducer  635 . 
     In accordance with an embodiment of the present invention, damaged TMR stack  612  of TMR transducer  635  may be repaired by exposing TMR stack  615  to atmosphere  650  comprising nitrogen, such as an atmosphere of nitrogen or nitric oxide. Upon repairing TMR stack  612 , a subsequent layer may be deposited onto TMR stack  612 . 
     With reference to  FIG. 7 , an isometric view of a repaired TMR transducer  735  of HDD slider  125  is presented in accordance with an embodiment of the present invention. Second ferromagnetic lead  420  is deposited subsequently on a surface of TMR stack  612  after being repaired with atmosphere  650 . TMR stack  615  may also be repaired with atmosphere  650  after a subsequent layer such as second ferromagnetic lead  420  has been deposited. Similarly as presented in  FIG. 5 , and analogues to electric current  550  and electrons  555 , electrons  755  are not trapped by oxygen vacancies in repaired TMR stack  612  and thus reduce the variations in resistance to current  750  and thereby reduce read-back signal noise from a magnetic transducer using TMR transducer  735 . 
     With reference to  FIG. 8 , a cross-section  800  of a magnetic transducer of an HDD slider  125  is presented in accordance with one embodiment of the present invention. Oxygen vacancy  865  in TMR stack  612  is created by plasma  625  ( FIG. 6 ) during the trimming of TMR stack  612  and is filled with nitrogen from atmosphere  650 . 
     Operation 
       FIGS. 9 ,  11 ,  13 , and  15  are flow charts of processes  900 ,  1100 ,  1300 , and  1500  respectively in which particular steps are performed in accordance with embodiments of the present invention for fabricating an overcoat for a TMR transducer and repairing a TMR transducer whereby read-back signal noise is reduced in read data from the TMR transducer.  FIGS. 10 ,  12 ,  14 , and  16  present cross-sections of an exemplary TMR transducer at sequential process steps of fabrication presented in processes  900 ,  1100 ,  1300 , and  1500  of  FIGS. 9 ,  11 ,  13 , and  15  respectively. Although specific steps are disclosed in processes  900 ,  1100 ,  1300 , and  1500 , such steps are exemplary. That is, the embodiments of the present invention are well suited to performing various other steps or variations of the steps recited in  FIGS. 9 ,  11 ,  13 , and  15 . Within the present embodiment, it should be appreciated that the steps of processes  900 ,  1100 ,  1300 , and  1500  may be performed by software, by hardware, by an assembly mechanism, through human interaction, or by any combination of software, hardware, assembly mechanism, and human interaction. 
     Process  900  will be described with reference to cross-section elements shown in  FIGS. 10   a - 10   c  of a detail of an HDD slider at process steps of fabrication of an overcoat in accordance with one embodiment of the present invention. 
     In step  901  of process  900 , TMR transducer  535 , at a suitable level of fabrication, is introduced into process  900  in an embodiment of the present invention. A suitable level of fabrication for TMR transducer  535  is after ABS  220  has been fabricated which exposes TMR transducer  535  as part of ABS  220 . 
     In step  910  of process  900 , ABS  220  is cleaned ( FIG. 10   a ) in an embodiment of the present invention. There are various cleaning methods available to those skilled in the art, such as non-directional plasma and directional ion beam, known as sputter etching. It is typical to perform the cleaning process in the apparatus that will deposit a subsequent layer. In accordance with an embodiment of the present invention, the subsequent layer to be deposited is adhesion layer  523 . The cleaning process is typically sputter etching performed in the sputtering chamber wherein the sputter deposition of adhesion layer  523  will be performed. 
     The sputter etch process comprises an ionized beam of argon (Ar + ) gas  1010 . Argon is a preferred sputter etch gas because of its relatively high atomic weight as a gas and its ability when ionized, to impart kinetic energy into a surface, thereby removing atoms from the surface being sputter etch cleaned. In the process of cleaning ABS  220 , oxygen atoms (O)  1020  from insulator barrier  415  may be dislodged, along with other atoms  1030  from ABS  220 , leaving oxygen vacancy  465  in insulator barrier  415  and causing damage. 
     In step  920  of process  900 , adhesion layer  523  is deposited ( FIG. 10   b ) in an embodiment of the present invention. An approximately stoichiometric silicon-nitride (SiN x ) compound comprising adhesion layer  523  is deposited onto ABS  220 . Various methods of depositing adhesion layer  523  are known to those skilled in the art. For example radio frequency plasma sputtering and ion beam sputtering are available for depositing approximately stoichiometric silicon-nitride. With any acceptable deposition method a plasma comprising Si +  and N +   1040  impinges upon ABS  220 . Thusly, adhesion layer  523  is coupled to ABS  220 . As adhesion layer  523  is deposited, nitrogen atoms from plasma Si +  and N +   1040  repair TMR stack  512  such as by filling oxygen vacancy  565  in insulator barrier  515 . Resulting adhesion layer  523  has a resistivity between 10 9  Ohm-cm and 10 14  Ohm-cm, a density between 2.95 g/cm 3  to 3.15 g/cm 3 , and hardness between 18 GPa and 25 GPa. 
     In step  930  of process  900 , carbon layer  324  is applied to ABS  220  and adhesion layer  523  ( FIG. 10   c ) in an embodiment of the present invention. Accordingly, ABS  220  is covered with overcoat  325 . Various methods of applying overcoat  325  are known to those skilled in the art. For example ion beam sputter deposition may be used to deposit a hydrogenated amorphous carbon layer; chemical vapor deposition (CVD) may be used to deposit a carbon layer; and filtered cathodic arc deposition may be used to deposit a tetrahedral amorphous carbon layer. The typical overcoat comprises adhesion layer  523  and carbon layer  324 . The scope of the embodiment of the present invention is not limited by the method used for applying an overcoat. These application methods and the resulting overcoat are not intended to be an extensive list but are presented only as examples for the sake of brevity and clarity. 
     In step  940  of process  900 , TMR transducer  535  is removed from process  900 , whereby a slider overcoat process for noise reduction of the TMR magnetic transducer is complete. 
     Process  1100  will be described with reference to cross-section elements shown in  FIGS. 12   a - 12   d  of a detail of an HDD slider at process steps of fabrication of an overcoat in accordance with one embodiment of the present invention. 
     In step  1101  of process  1100 , TMR transducer  535 , at a suitable level of fabrication, is introduced into process  1100  in an embodiment of the present invention. A suitable level of fabrication for TMR transducer  535  is after ABS  220  has been fabricated which exposes TMR transducer  535  as part of ABS  220 . 
     In step  1110  of process  1100 , ABS  220  is cleaned ( FIG. 12   a ) in an embodiment of the present invention. There are various cleaning methods available to those skilled in the art, such as non-directional plasma and directional ion beam, known as sputter etching. It is typical to perform the cleaning process in the apparatus that will deposit a subsequent layer. In accordance with an embodiment of the present invention, the subsequent layer to be deposited is adhesion layer  1223 . The cleaning process is typically sputter etching performed in the sputtering chamber wherein the sputter deposition of adhesion layer  1223  will be performed. 
     The sputter etch process comprises an Ar +  plasma  1010 . Argon is a preferred sputter etch gas because of its relatively high atomic weight as a gas and its ability when ionized, to impart kinetic energy into a surface, thereby removing atoms from the surface being sputter etch cleaned. In the process of cleaning ABS  220 , oxygen atoms(O)  1020  from insulator barrier  415  may be dislodged, along with other atoms  1030  from ABS  220 , leaving oxygen vacancy  465  in insulator barrier  415 . Since ABS  220  is being cleaned, damage to TMR stack  412 , such as oxygen vacancy  465  typically occurs closest to ABS  220 . 
     In step  1120  of process  1100 , ABS  220  is exposed to atmosphere  1210  ( FIG. 12   b ) comprising nitrogen, such as nitrogen or nitric oxide in an embodiment of the present invention. Atmosphere  1210  comprising nitrogen is back-filled into a sputtering chamber prior to the deposition of adhesion layer  1223 . The back-filling process comprises controlling the flow rate of nitrogen or nitric oxide into the sputtering chamber prior to the deposition of adhesion layer  1223  and controlling the time that TMR transducer  535  is exposed to atmosphere  1210 . Nitrogen atoms from atmosphere  1210  repair TMR stack  1212 , such as by filling oxygen vacancy  1265  in insulator barrier  1215 . 
     In step  1130  of process  1100 , adhesion layer  1223  ( FIG. 12   c ) comprising Si is deposited onto ABS  220  in an embodiment of the present invention. Various methods of depositing adhesion layer  1223  are known to those skilled in the art. For example radio frequency plasma sputtering and ion beam sputtering are available for depositing silicon. With any acceptable deposition method a plasma comprising Si +   1240  impinges upon ABS  220 . Thusly, adhesion layer  1223  is coupled to ABS  220 . 
     In step  1140  of process  1100 , carbon layer  324  is applied to ABS  220  and adhesion layer  1223  ( FIG. 12   d ) in an embodiment of the present invention. Accordingly, ABS  220  is covered with overcoat  325 . Various methods of applying overcoat  325  are known to those skilled in the art. For example ion beam sputter deposition may be used to deposit a hydrogenated amorphous carbon layer; chemical vapor deposition (CVD) may be used to deposit a carbon layer; and filtered cathodic arc deposition may be used to deposit a tetrahedral amorphous carbon layer. The typical overcoat comprises adhesion layer  1223  and carbon layer  324 . The scope of the embodiment of the present invention is not limited by the method used for applying an overcoat. These application methods and the resulting overcoat are not intended to be an extensive list but are presented only as examples for the sake of brevity and clarity. 
     In step  1150  of process  1100 , TMR transducer  535  is removed from process  1100 , whereby a slider overcoat process for noise reduction of the TMR magnetic transducer is complete. 
     Process  1300  will be described with reference to cross-section elements shown in  FIGS. 14   a - 14   d  of a detail of an HDD slider at process steps of repair of TMR stack  412  and fabrication of overcoat  325  in accordance with one embodiment of the present invention. 
     In step  1301  of process  1300 , TMR transducer  535 , at a suitable level of fabrication, is introduced into process  1300  in an embodiment of the present invention. A suitable level of fabrication for TMR transducer  535  is after ABS  220  has been fabricated which exposes TMR transducer  535  as part of ABS  220 , and after TMR stack  412  has been damaged, such as with oxygen vacancy  465 . 
     In step  1310  of process  1300 , damaged TMR transducer  535  is cleaned ( FIG. 14   a  and alternatively  FIG. 12   a ) in an embodiment of the present invention. There are various cleaning methods available to those skilled in the art, such as non-directional plasma and directional ion beam, known as sputter etching. Cleaning in step  1310  is required to remove possible contamination from TMR transducer  535  prior to the deposition of subsequent adhesion layer  1223 . 
     The non-directional plasma process could be less vigorous than a typical sputter etching process. It is usually classified as low damage plasma etching. Both non-directional plasma such as low damage plasma and sputter etching are well known in the art. Non-directional plasma with ionized atmosphere  1420  could be less aggressive than sputter etching and is less likely to cause any further damage to TMR stack  412 , such as affecting oxygen vacancy  465 . 
     In accordance with an embodiment of the present invention, and presented in  FIG. 14   a , step  1310  comprises non-directional plasma. Non-directional plasma comprises an ionized atmosphere  1420 , typically comprising ionized gas or mixture of argon, or nitrogen, or oxygen. Ionized atmosphere  1420  chemically reacts with possible contamination on TMR transducer  535  and reacted contaminants are vented in exhaust  1430 . 
     In accordance with an embodiment of the present invention, and presented in  FIG. 12   a , step  1310  comprises sputter etching. Sputter etching comprises highly energetic ions of Ar +   1010 , which impinge upon an ABS  220  and TMR transducer  535  to dislodge atoms of possible contamination. 
     In step  1320  of process  1300 , TMR transducer  535  is exposed to atmosphere  1210  ( FIG. 14   b ) comprising nitrogen, such as nitrogen gas, nitric oxide gas, nitrogen plasma, or nitric oxide plasma in an embodiment of the present invention. Atmosphere  1210  comprising nitrogen is back-filled into a sputtering chamber prior to the deposition of adhesion layer  1223 . The back-filling process comprises controlling the flow rate of nitrogen or nitric oxide into the sputtering chamber prior to the deposition of adhesion layer  1223  and controlling the time that TMR transducer  535  is exposed to atmosphere  1210 . Nitrogen atoms from atmosphere  1210  repair TMR stack  1212 , such as by filling oxygen vacancy  1465  in insulator barrier  1415 . 
     In step  1330  of process  1300 , adhesion layer  1223  ( FIG. 14   c ) comprising Si is deposited onto ABS  220 , which comprises TMR transducer  535 , in an embodiment of the present invention. Various methods of depositing adhesion layer  1223  are known to those skilled in the art. For example radio frequency plasma sputtering and ion beam sputtering are available for depositing silicon. With any acceptable deposition method a plasma comprising Si +   1240  impinges upon ABS  220 . Thusly, adhesion layer  1223  is coupled to ABS  220 . 
     In step  1340  of process  1300 , carbon layer  324  is applied to ABS  220  and adhesion layer  1223  ( FIG. 14   d ) in an embodiment of the present invention. Accordingly, ABS  220  is covered with overcoat  325 . Various methods of applying overcoat  325  are known to those skilled in the art. For example ion beam sputter deposition may be used to deposit a hydrogenated amorphous carbon overcoat; chemical vapor deposition (CVD) may be used to deposit carbon layer; and filtered cathodic arc deposition may be used to deposit a tetrahedral amorphous carbon layer. The typical overcoat comprises adhesion layer  1223  and carbon layer  324 . The scope of the embodiment of the present invention is not limited by the method used for applying a carbon overcoat. These application methods and the resulting overcoat are not intended to be an extensive list but are presented only as examples for the sake of brevity and clarity. 
     In step  1350  of process  1300 , TMR transducer  535  is removed from process  1300 , whereby the TMR transducer of an HDD slider is repaired and an overcoat process is complete for noise reduction of the TMR magnetic transducer. 
     Process  1500  will be described with reference to cross-section elements shown in  FIGS. 16   a - 16   c  of a detail of a TMR transducer at process steps of fabrication in accordance with one embodiment of the present invention. 
     In step  1501  of process  1500 , TMR transducer  635 , at a suitable level of fabrication, is introduced into process  1500  in an embodiment of the present invention. A suitable level of fabrication for TMR transducer  635  is after TMR stack  612  is deposited onto first ferromagnetic lead  410  and prior to the deposition of subsequent layer  1620 . 
     In step  1510  of process  1500 , TMR stack  612  is trimmed ( FIG. 16   a ) in an embodiment of the present invention. There are various trimming methods available to those skilled in the art, such as ion milling, and reactive ion etching (RIE). Trimming is performed through a photolithographic pattern, well known in the art, but not presented for the sake of brevity and clarity. In accordance with an embodiment of the present invention, subsequent layer  1620  to be deposited is second ferromagnetic lead  420  ( FIG. 4  and  FIG. 16   c ). 
     TMR stack  612  may be damaged in the trimming process. Such damage can possibly be oxygen atoms, (O)  1630  dislodged from insulator barrier  615 , leaving oxygen vacancy  1665  in insulator barrier  615 . Oxygen vacancy  1665  can cause noise to increase in read data from TMR transducer  735 . 
     In step  1520  of process  1500 , TMR stack  612  is exposed to atmosphere  650  ( FIG. 6  and  FIG. 16   b ) comprising nitrogen in an embodiment of the present invention. Atmosphere  650  comprising nitrogen is back-filled into a sputtering chamber prior to the deposition of subsequent layer  1620  such as second ferromagnetic lead  420  ( FIGS. 7 ,  8 , and  16   c ). The back-filling process comprises controlling the flow rate of nitrogen or nitric oxide into the sputtering chamber and controlling the time that TMR transducer  535  is exposed to atmosphere  650  prior to the deposition of subsequent layer  1620  such as second ferromagnetic lead  420  ( FIG. 4 ). 
     In step  1530  of process  1500 , a subsequent layer  1620  ( FIG. 16   c ) is deposited in an embodiment of the present invention. In accordance with an embodiment of the present invention, subsequent layer  1620  comprises second ferromagnetic lead  420 . Subsequent layer  1620  may be any layer deposited on top of TMR stack  612 , such as an adhesion layer of Si or an encapsulating layer such as alumina, but for the sake of brevity and clarity only second ferromagnetic lead  420  is discussed. 
     In step  1540  of process  1500 , TMR transducer  735  is removed from process  1500 , whereby the repair of TMR stack  612  of TMR transducer  735  is complete. 
     The present invention, in the various presented embodiments allows for the reduction of read-back signal noise in the read data from a TMR magnetic transducer. The reduction of read-back signal noise is accomplished in a cost effective manner by processing the TMR magnetic transducer with nitrogen compounds and/or atmospheres, which fill oxygen vacancy created in the insulator barrier by prerequisite cleaning processes. 
     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The embodiments described herein were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.