Abstract:
A thin-film magnetic head has an inductive write head element including an upper core layer with a front end section magnetically coupling with an upper magnetic pole, a lower core layer with a front end section magnetically coupling with a lower magnetic pole, a coil conductor formed to pass between the upper core layer and the lower core layer, and an coil insulation layer for sandwiching the coil conductor. At least one thermal diffusion layer with a good thermal conductivity is formed on the coil insulation layer at an outside region of the upper core layer, or at least one thermal diffusion layer is formed at an outside region of the upper core layer to contact with a part of the coil conductor or to constitute a part of the coil conductor.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a thin-film magnetic head provided with at least an inductive write head element and to a manufacturing method of the thin-film magnetic head.  
         DESCRIPTION OF THE RELATED ART  
         [0002]    In a thin-film magnetic head provided with an inductive write head element, a thin-film coil conductor is extremely heated due to a write current flowing there through and thus its environmental temperature is greatly increased. However, in conventional thin-film magnetic heads, no effective countermeasure is taken against the rise in temperature due to the generated heat of the coil conductor. Most of the conventional heads only adopt a heat-radiation structure relaying entirely on heat conduction of the insulation material surrounding the coil conductor.  
           [0003]    Japanese utility model publication No. 06084507A discloses thermal diffusion layers of BeO or Ag directly laminated on and contacted with an upper magnetic pole layer and a lower magnetic pole layer to restrain increase in temperature of the upper and lower magnetic pole layers.  
           [0004]    However, such direct lamination of the metallic layer on the upper and lower magnetic pole layers, although it is made of a non-magnetic metallic material, will have a detrimental effect on the magnetic characteristics of the head, and also will not provide sufficient heat-radiation effect to the upper and lower magnetic pole layers.  
           [0005]    If the rise in temperature due to heating of the coil conductor increases in large amount, the insulation layer surrounding the coil conductor will thermally expand and jut toward an air bearing surface (ABS) of the head. This projection of the insulation layer may come into contact with a magnetic medium in operation of the head. Also, because of heating, the coil conductor itself may be disconnected.  
           [0006]    Particularly, since a track width of the thin-film magnetic head becomes narrowed and the magnetic head itself becomes downsized to satisfy the requirement for ever increasing data storage capacities and densities in today&#39;s magnetic disk drive apparatus, it is very difficult to radiate the generated heat from the thin-film magnetic head. Also, since the space between the magnetic medium surface and the magnetic head is narrowed, occurrence of the projection of the insulation layer becomes significant problem. Furthermore, since there is the tendency to increase the coercive force Hc of the magnetic medium in order to enhance data storage densities and therefore the write current is becoming increasingly larger, heating of the coil conductor presents serious problem.  
         SUMMARY OF THE INVENTION  
         [0007]    It is therefore an object of the present invention to provide a thin-film magnetic head and a manufacturing method of the head, whereby thermal expansion toward ABS of the head and disconnection of a coil conductor itself due to heating of the coil conductor can be effectively prevented.  
           [0008]    According to the present invention, a thin-film magnetic head has an inductive write head element including an upper core layer with a front end section (end section of ABS side) magnetically coupling with an upper magnetic pole, a lower core layer with a front end section magnetically coupling with a lower magnetic pole, a coil conductor formed to pass between the upper core layer and the lower core layer, and an coil insulation layer for sandwiching the coil conductor. Particularly, according to the present invention, at least one thermal diffusion layer with a good thermal conductivity is formed on the coil insulation layer at an outside region of the upper core layer, or at least one thermal diffusion layer is formed at an outside region of the upper core layer to contact with a part of the coil conductor or to constitute a part of the coil conductor.  
           [0009]    Since the thermal diffusion layer is formed at the outside region of the upper core layer, heat-radiation effect can be expected without any deleterious effect on the magnetic performance of the inductive write head element. Also, since the thermal diffusion layer expands to cover the outside region of the upper core layer, within which region the most of the coil conductor is located, sufficient heat-radiation effect can be obtained. As a result, not only contact of the magnetic head with a magnetic medium in operation due to the thermal expansion toward the ABS but also disconnection of the coil conductor itself, caused by heating of the coil conductor, can be effectively prevented.  
           [0010]    It is preferred that the thermal diffusion layer is formed at a rear (opposite to ABS side) outside region of the upper core layer, and/or that the thermal diffusion layer is formed at a lateral (lateral side seen from ABS) outside region of the upper core layer  
           [0011]    It is also preferred that only a thin coating film is formed on the thermal diffusion layer to improve heat-radiation performance. In this case, the coating film may be made of a material selected from Ti, Cr, Ta, Ni, Fe, Co, Au, Pt, Rh and Ru, or an alloy containing at least Ti, Cr, Ta, Ni, Fe or Co.  
           [0012]    It is preferred that the thermal diffusion layer is made of a material with a thermal conductivity higher than that of Al 2 O 3  and/or a material with a thermal expansion coefficient lower than that of Al 2 O 3 . The thermal diffusion layer may be made of a material selected from Au, Ag, Si, Zn, Al, Ir, Cd, Sb, W, Ta, Fe, Pb, Ni, Pt, Pd, Mg and Mo, or an alloy containing at least one of Au, Ag, Si, Zn, Al, Ir, Cd, Sb, W, Ta, Fe, Pb, Ni, Pt, Pd, Mg and Mo.  
           [0013]    The present invention also concerns to a manufacturing method of a thin-film magnetic head including a step of forming a lower core layer with a front end section magnetically coupling with a lower magnetic pole, a step of forming a first coil insulation layer at least on the lower core layer, a step of forming a coil conductor on the first coil insulation layer, having a pattern to pass on the lower core layer, a step of forming a second coil insulation layer on the coil conductor, and a step of forming an upper core layer with a front end section magnetically coupling with an upper magnetic pole, on the second coil insulation layer, or to a manufacturing method of a thin-film magnetic head including a step of forming a lower core layer with a front end section magnetically coupling with a lower magnetic pole, a step of forming a first coil insulation layer at least on the lower core layer, a step of forming a coil conductor on the first coil insulation layer, having a pattern to pass on the lower core layer, a step of forming a second coil insulation layer on the coil conductor, a step of forming a coil conductor on the second coil insulation layer, having a pattern to pass on the lower core layer, a step of forming a third coil insulation layer on the coil conductor, and a step of forming an upper core layer with a front end section magnetically coupling with an upper magnetic pole, on the third coil insulation layer. Particularly, according to the present invention, at least one thermal diffusion layer with a good thermal conductivity is formed on the second coil insulation layer or on the third coil insulation layer at an outside region of the upper core layer.  
           [0014]    It is preferred that the method further includes a step of forming bumps on connection terminals to be connected with the coil conductor, and that the thermal diffusion layer is formed in the step of forming the bumps. It is also preferred that the method further includes a step of forming under films for bumps formed on connection terminals to be connected with the coil conductor, and that the thermal diffusion layer is formed in the step of forming the under films. If the thermal diffusion layer is formed in the same forming process of the bumps or the under films for bumps, no additional process is required.  
           [0015]    It is further preferred that the thermal diffusion layer is formed at a rear outside region and/or a lateral outside region of the upper core layer.  
           [0016]    In a manufacturing method of a thin-film magnetic head according to the present invention, at least one thermal diffusion layer with a good thermal conductivity is formed at an outside region of the upper core layer, so that the thermal diffusion layer is in contact with a part of the coil conductor or constitutes a part of the coil conductor.  
           [0017]    In this case, it is preferred that the thermal diffusion layer is formed in the step of forming the coil conductor. If the thermal diffusion layer is formed in the same forming process of the coil conductor, no additional process is required.  
           [0018]    It is also preferred that only a thin coating film is formed on the thermal diffusion layer to improve heat-radiation performance. In this case, the coating film may be made of a material selected from Ti, Cr, Ta, Ni, Fe, Co, Au, Pt, Rh and Ru, or an alloy containing at least Ti, Cr, Ta, Ni, Fe or Co.  
           [0019]    It is preferred that the thermal diffusion layer is made of a material with a thermal conductivity higher than that of Al 2 O 3  and/or a material with a thermal expansion coefficient lower than that of Al 2 O 3 . The thermal diffusion layer may be made of a material selected from Au, Ag, Si, Zn, Al, Ir, Cd, Sb, W, Ta, Fe, Pb, Ni, Pt, Pd, Mg and Mo, or an alloy containing at least one of Au, Ag, Si, Zn, Al, Ir, Cd, Sb, W, Ta, Fe, Pb, Ni, Pt, Pd, Mg and Mo.  
           [0020]    Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 shows a plane view schematically illustrating a single thin-film magnetic head formed on a wafer surface in a preferred embodiment according to the present invention;  
         [0022]    [0022]FIGS. 2 a  to  2   g  show plane views schematically illustrating an example of manufacturing processes of the thin-film magnetic head in the embodiment of FIG. 1;  
         [0023]    [0023]FIGS. 3 a  to  3   g  show sectional views along an A-A line of FIGS. 2 a  to  2   g , respectively;  
         [0024]    [0024]FIGS. 4 a  to  4   g  show plane views schematically illustrating another example of manufacturing processes of a thin-film magnetic head in a modification of the embodiment of FIG. 1;  
         [0025]    [0025]FIGS. 5 a  to  5   g  show sectional views along an A-A line of FIGS. 4 a  to  4   g , respectively;  
         [0026]    [0026]FIG. 6 shows a plane view schematically illustrating a single thin-film magnetic head formed on a wafer surface in another embodiment according to the present invention;  
         [0027]    [0027]FIG. 7 shows a plane view schematically illustrating a single thin-film magnetic head formed on a wafer surface in a further embodiment according to the present invention;  
         [0028]    [0028]FIG. 8 shows a plane view schematically illustrating a single thin-film magnetic head formed on a wafer surface in a still further embodiment according to the present invention;  
         [0029]    [0029]FIGS. 9 a  to  9   g  show plane views schematically illustrating an example of manufacturing processes of the thin-film magnetic head in the embodiment of FIG. 8; and  
         [0030]    [0030]FIGS. 10 a  to  10   g  show sectional views along an A-A line of FIGS. 9 a  to  9   g , respectively. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    [0031]FIG. 1 schematically illustrates a single thin-film magnetic head formed on a wafer surface in a preferred embodiment according to the present invention. In this embodiment, the thin-film magnetic head consists of a composite thin-film magnetic head provided with an inductive write head element and a magnetoresistive effect (MR) read head element.  
         [0032]    In the figure, reference numerals  10   a  and  10   b  denote connection terminals or pads for the MR read head element,  11   a  and  11   b  denote lead conductors for the MR read head element, one ends of which are connected to the respective pads  10   a  and  10   b ,  12   a  and  12   b  denote contacts for the MR read head element, connected to the other ends of the respective lead conductors  11   a  and  11   b ,  13   a  and  13   b  denote MR lead electrodes connected to the respective contacts  12   a  and  12   b ,  14  denotes an MR film both end portions of which are connected to the respective MR lead electrodes  13   a  and  13   b ,  15   a  and  15   b  denote connection terminals or pads for the inductive write head element,  16   a  and  16   b  denote lead conductors for the inductive write head element, one ends of which are connected to the respective pads  15   a  and  15   b ,  17  denotes a first layer coil conductor, one end of which is connected to the other end of the lead conductor  16   a ,  18  denotes a second layer coil conductor, one end of which is connected to the other end of the lead conductor  16   b ,  19  denotes a coil connection part for connecting the first layer coil conductor  17  and the second layer coil conductor  18  with each other,  20  denotes a coil insulation layer (a first coil insulation layer  20   a , a second coil insulation layer  20   b  and a third coil insulation layer  20   c ) surrounding the first and second layer coil conductors  17  and  18 ,  21  denotes a lower shield layer,  22  denotes an upper shield layer doubling as a lower core layer (a first upper shield layer  22   a  and a second upper shield layer doubling as a lower core layer  22   b ),  23  denotes an upper core layer,  24  denotes a back gap part for magnetically connecting the lower core layer  22  and the upper core layer  23  in order to form a magnetic path, and  25  denotes a thermal diffusion layer laminated on the coil insulation layer  20  at the rear (opposite to ABS side) outside region of the upper core layer  23 , respectively.  
         [0033]    [0033]FIGS. 2 a  to  2   g  schematically illustrate an example of manufacturing processes of the thin-film magnetic head in this embodiment, and FIGS. 3 a  to  3   g  illustrate sections along an A-A line of FIGS. 2 a  to  2   g , respectively. Hereinafter, the manufacturing processes of the thin-film magnetic head in this embodiment will be described with reference to these figures.  
         [0034]    First, an under film and other necessary film are deposited on a wafer. Next, as shown in FIGS. 2 a  and  3   a , the lower shield layer  21  is formed on the under film, an insulation layer is deposited thereon, and then its surface is flattened by executing chemical mechanical polishing (CMP).  
         [0035]    Then, as shown in FIGS. 2 b  and  3   b , a first read gap layer  26   a  is formed thereon, the MR film  14  and the MR lead electrodes  13   a  and  13   b  are formed, a second read gap layer  26   b  is formed thereon, and thereafter the first upper shield layer  22   a  is formed thereon.  
         [0036]    Then, as shown in FIGS. 2 c  and  3   c , the second upper shield layer doubling as the lower core layer  22   b  is formed on the first upper shield layer  22   a , an insulation layer is deposited thereon, and then its surface is flattened by executing CMP.  
         [0037]    Thereafter, as shown in FIGS. 2 d  and  3   d , the first coil insulation layer  20   a  is deposited, the first layer coil conductor  17  and the coil connection part  19  are formed thereon, and then the second coil insulation layer  20   b  is formed to cover the first layer coil conductor  17 .  
         [0038]    Then, as shown in FIGS. 2 e  and  3   e , the second layer coil conductor  18  and the coil connection part  19  are formed on the second coil insulation layer  20   b , and the third coil insulation layer  20   c  is formed thereon. The pads  10   a ,  10   b ,  15   a  and  15   b  and the lead conductors  11   a ,  11   b ,  16   a  and  16   b  are formed in this stage.  
         [0039]    Then, as shown in FIGS. 2 f  and  3   f , the upper core layer  23  is formed on the third coil insulation layer  20   c  at its front side (ABS side) region.  
         [0040]    Thereafter, as shown in FIGS. 2 g  and  3   g , under films for bumps are formed on the pads  10   a ,  10   b ,  15   a  and  15   b , and then bumps are formed on the under films. In the same process of forming the bumps, the thermal diffusion layer  25  is formed on the third coil insulation layer  20   c  at the rear (opposite to ABS side) outside region of the upper core layer  23 .  
         [0041]    The thermal diffusion layer  25  is made of a material with a higher thermal conductivity than that of a protection layer of Al 2 O 3 . Preferably, the thermal diffusion layer  25  is made of the same material as the bumps such as Cu for example in order to simplify the manufacturing process. However, as for the thermal diffusion layer  25 , any material selected from Au, Ag, Si, Zn, Al, Ir, Cd, Sb, W, Ta, Fe, Pb, Ni, Pt, Pd, Mg and Mo or an alloy containing at least one of these materials can be used. It is also preferred to use as the thermal diffusion layer  25  a material with a lower thermal expansion coefficient than that of a protection layer of Al 2 O 3 .  
         [0042]    Although it is not shown in the figures, thereafter, the protection layer such as Al 2 O 3  is formed on the upper core layer  23  and the thermal diffusion layer  25 . If no protection layer is formed but only a thin coating film is formed on the thermal diffusion layer  25 , the heat-radiation effect will be more improved. This coating film will be made of a material selected from Ti, Cr, Ta, Ni, Fe, Co, Au, Pt, Rh and Ru or an alloy containing at least Ti, Cr, Ta, Ni, Fe or Co.  
         [0043]    As aforementioned, according to this embodiment, since the thermal diffusion layer  25  is formed on the third coil insulation layer  20   c  at the rear outside region of the upper core layer  23 , heat-radiation effect can be expected without any deleterious effect on the magnetic performance of the inductive write head element. Also, since the thermal diffusion layer  25  expands to cover the outside region of the upper core layer  23 , within which region the most of the coil conductors  17  and  18  are located, sufficient heat-radiation effect can be obtained. As a result, not only contact of the magnetic head with a magnetic medium in operation due to the heat expansion toward the ABS but also disconnection of the coil conductors  17  and  18  themselves, caused by heating of the coil conductors  17  and  18 , can be effectively prevented.  
         [0044]    Furthermore, according to this embodiment, the thermal diffusion layer  25  is formed in the same forming process of the bumps, no additional process is required. Also, as the thermal diffusion layer  25  can be made thick as well as the bumps, greater thermal radiation and thermal storage effect can be expected.  
         [0045]    It should be noted that each layer except for the thermal diffusion layer  25 , the protection layer and the coating film can be made of any material generally used in this technical field, and can be formed (deposited, patterned) by using any method known in this field.  
         [0046]    Although in this embodiment the upper shield layer doubling as the lower core layer  22  is formed in the two layer structure of the first upper shield layer  22   a  and the second upper shield layer doubling as the lower core layer  22   b , it is possible to form it in a single layer structure. In this embodiment the coil conductor is formed also in the two layer structure of the first layer coil conductor  17  and the second layer coil conductor  18 . Nevertheless, the coil conductor may be formed in a multilayer structure of more than two layers or in a single layer structure.  
         [0047]    [0047]FIGS. 4 a  to  4   g  schematically illustrate another example of manufacturing processes of a thin-film magnetic head in a modification of the embodiment of FIG. 1, and FIGS. 5 a  to  5   g  illustrate sections along an A-A line of FIGS. 4 a  to  4   g , respectively. Hereinafter, the manufacturing processes of the thin-film magnetic head in this modification will be described with reference to these figures. In the modification of FIGS.  4   a  to  4   g  and FIGS. 5 a  to  5   g , the same elements as these in the embodiment of FIG. 1, FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g  use the same reference numerals, respectively.  
         [0048]    First, an under film and other necessary film are deposited on a wafer. Next, as shown in FIGS. 4 a  and  5   a , the lower shield layer  21  is formed on the under film, an insulation layer is deposited thereon, and then its surface is flattened by executing CMP.  
         [0049]    Then, as shown in FIGS. 4 b  and  5   b , a first read gap layer  26   a  is formed thereon, the MR film  14  and the MR lead electrodes  13   a  and  13   b  are formed, a second read gap layer  26   b  is formed thereon, and thereafter the first upper shield layer  22   a  is formed thereon.  
         [0050]    Then, as shown in FIGS. 4 c  and  5   c , the second upper shield layer doubling as the lower core layer  22   b  is formed on the first upper shield layer  22   a , an insulation layer is deposited thereon, and then its surface is flattened by executing CMP.  
         [0051]    Thereafter, as shown in FIGS. 4 d  and  5   d , the first coil insulation layer  20   a  is deposited, the first layer coil conductor  17  and the coil connection part  19  are formed thereon, and then the second coil insulation layer  20   b  is formed to cover the first layer coil conductor  17 .  
         [0052]    Then, as shown in FIGS. 4 e  and  5   e , the second layer coil conductor  18  and the coil connection part  19  are formed on the second coil insulation layer  20   b , and the third coil insulation layer  20   c  is formed thereon. The pads  10   a ,  10   b ,  15   a  and  15   b  and the lead conductors  11   a ,  11   b ,  16   a  and  16   b  are formed in this stage.  
         [0053]    Then, as shown in FIGS. 4 f  and  5   f , the upper core layer  23  is formed on the third coil insulation layer  20   c  at its front side (ABS side) region.  
         [0054]    Thereafter, as shown in FIGS. 4 g  and  5   g , under films for bumps are formed on the pads  10   a ,  10   b ,  15   a  and  15   b . In the same process of forming the under films for bumps, a thermal diffusion layer  55  is formed on the third coil insulation layer  20   c  at the rear (opposite to ABS side) outside region of the upper core layer  23 . Thus, the thermal diffusion layer  55  in this modification is thinner than the thermal diffusion layer  25  in the embodiment of FIG. 1, FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g.    
         [0055]    The thermal diffusion layer  55  is made of a material with a higher thermal conductivity than that of a protection layer of Al 2 O 3 . Preferably, the thermal diffusion layer  55  is made of the same material as the under films for bumps such as Cu for example in order to simplify the manufacturing process. However, as for the thermal diffusion layer  55 , any material selected from Au, Ag, Si, Zn, Al, Ir, Cd, Sb, W, Ta, Fe, Pb, Ni, Pt, Pd, Mg and Mo or an alloy containing at least one of these materials can be used. It is also preferred to use as the thermal diffusion layer  55  a material with a lower thermal expansion coefficient than that of a protection layer of Al 2 O 3 .  
         [0056]    Although it is not shown in the figures, thereafter, on the under films formed on the pads  10   a ,  10   b ,  15   a  and  15   b , bumps are formed. Then, the protection layer such as Al 2 O 3  is formed on the upper core layer  23  and the thermal diffusion layer  55 . If no protection layer is formed but only a thin coating film is formed on the thermal diffusion layer  55 , the heat-radiation effect will be more improved. This coating film will be made of a material selected from Ti, Cr, Ta, Ni, Fe, Co, Au, Pt, Rh and Ru or an alloy containing at least Ti, Cr, Ta, Ni, Fe or Co.  
         [0057]    Operations and advantages in this modification are the same as those in the embodiment of FIG. 1, FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g.    
         [0058]    It should be noted that each layer except for the thermal diffusion layer  55 , the protection layer and the coating film can be made of any material generally used in this technical field, and can be formed (deposited, patterned) by using any method known in this field.  
         [0059]    Although in this modification the upper shield layer doubling as the lower core layer  22  is formed in the two layer structure of the first upper shield layer  22   a  and the second upper shield layer doubling as the lower core layer  22   b , it is possible to form it in a single layer structure. In this modification the coil conductor is formed also in the two layer structure of the first layer coil conductor  17  and the second layer coil conductor  18 . Nevertheless, the coil conductor may be formed in a multilayer structure of more than two layers or in a single layer structure.  
         [0060]    [0060]FIG. 6 schematically illustrates a single thin-film magnetic head formed on a wafer surface in another embodiment according to the present invention. In this embodiment, the thin-film magnetic head consists of a composite thin-film magnetic head provided with an inductive write head element and an MR read head element. In the embodiment, the same elements as these in the embodiment of FIG. 1, FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g  use the same reference numerals, respectively.  
         [0061]    In the figure, reference numerals  10   a  and  10   b  denote connection terminals or pads for the MR read head element,  11   a  and  11   b  denote lead conductors for the MR read head element, one ends of which are connected to the respective pads  10   a  and  10   b ,  12   a  and  12   b  denote contacts for the MR read head element, connected to the other ends of the respective lead conductors  11   a  and  11   b ,  13   a  and  13   b  denote MR lead electrodes connected to the respective contacts  12   a  and  12   b ,  14  denotes an MR film both end portions of which are connected to the respective MR lead electrodes  13   a  and  13   b ,  15   a  and  15   b  denote connection terminals or pads for the inductive write head element,  16   a  and  16   b  denote lead conductors for the inductive write head element, one ends of which are connected to the respective pads  15   a  and  15   b ,  17  denotes a first layer coil conductor, one end of which is connected to the other end of the lead conductor  16   a ,  18  denotes a second layer coil conductor, one end of which is connected to the other end of the lead conductor  16   b ,  19  denotes a coil connection part for connecting the first layer coil conductor  17  and the second layer coil conductor  18  with each other,  20  denotes a coil insulation layer surrounding the coil conductors  17  and  18 ,  21  denotes a lower shield layer,  22  denotes an upper shield layer doubling as a lower core layer,  23  denotes an upper core layer,  24  denotes a back gap part for magnetically connecting the lower core layer  22  and the upper core layer  23  in order to form a magnetic path, and  65   a  and  65   b  denote thermal diffusion layers laminated on the coil insulation layer  20  at the lateral outside regions of the upper core layer  23 , respectively.  
         [0062]    The manufacturing processes of the thin-film magnetic head in this embodiment are the substantially same as those shown in FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g  and in FIGS. 4 a  to  4   g  and FIGS. 5 a  to  5   g.    
         [0063]    In the embodiment, since the thermal diffusion layers  65   a  and  65   b  broadly expand to cover the side outside regions of the upper core layer  23 , more larger thermal radiation and thermal storage effect can be expected. Other configurations, operations and advantages in this modification are the same as those in the embodiment of FIG. 1, FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g  and in the modification of FIGS. 4 a  to  4   g  and FIGS. 5 a  to  5   g.    
         [0064]    [0064]FIG. 7 schematically illustrates a single thin-film magnetic head formed on a wafer surface in a further embodiment according to the present invention. In this embodiment, the thin-film magnetic head consists of a composite thin-film magnetic head provided with an inductive write head element and an MR read head element. In the embodiment, the same elements as these in the embodiment of FIG. 1, FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g  use the same reference numerals, respectively.  
         [0065]    In the figure, reference numerals  10   a  and  10   b  denote connection terminals or pads for the MR read head element,  11   a  and  11   b  denote lead conductors for the MR read head element, one ends of which are connected to the respective pads  10   a  and  10   b ,  12   a  and  12   b  denote contacts for the MR read head element, connected to the other ends of the respective lead conductors  11   a  and  11   b ,  13   a  and  13   b  denote MR lead electrodes connected to the respective contacts  12   a  and  12   b ,  14  denotes an MR film both end portions of which are connected to the respective MR lead electrodes  13   a  and  13   b ,  15   a  and  15   b  denote connection terminals or pads for the inductive write head element,  16   a  and  16   b  denote lead conductors for the inductive write head element, one ends of which are connected to the respective pads  15   a  and  15   b ,  17  denotes a first layer coil conductor, one end of which is connected to the other end of the lead conductor  16   a ,  18  denotes a second layer coil conductor, one end of which is connected to the other end of the lead conductor  16   b ,  19  denotes a coil connection part for connecting the first layer coil conductor  17  and the second layer coil conductor  18  with each other,  20  denotes a coil insulation layer surrounding the coil conductors  17  and  18 ,  21  denotes a lower shield layer,  22  denotes an upper shield layer doubling as a lower core layer,  23  denotes an upper core layer,  24  denotes a back gap part for magnetically connecting the lower core layer  22  and the upper core layer  23  in order to form a magnetic path, and  75  denotes a thermal diffusion layer laminated on the coil insulation layer  20  at the rear outside region of and the lateral outside regions of the upper core layer  23 , respectively.  
         [0066]    The manufacturing processes of the thin-film magnetic head in this embodiment are the substantially same as those shown in FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g  and in FIGS. 4 a  to  4   g  and FIGS. 5 a  to  5   g.    
         [0067]    In the embodiment, since the thermal diffusion layer  75  more broadly expand to cover not only the rear outside region of but also the side outside regions of the upper core layer  23 , extremely larger thermal radiation and thermal storage effect can be expected. Other configurations, operations and advantages in this modification are the same as those in the embodiment of FIG. 1, FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g , in the modification of FIGS. 4 a  to  4   g  and FIGS. 5 a  to  5   g , and in the embodiment of FIG. 6.  
         [0068]    [0068]FIG. 8 schematically illustrates a single thin-film magnetic head formed on a wafer surface in a still further embodiment according to the present invention. In this embodiment, the thin-film magnetic head consists of a composite thin-film magnetic head provided with an inductive write head element and an MR read head element. In the embodiment, the same elements as these in the embodiment of FIG. 1, FIGS. 2 a  to  2   g  and FIGS. 3 a  to  3   g  use the same reference numerals, respectively.  
         [0069]    In the figure, reference numerals  10   a  and  10   b  denote connection terminals or pads for the MR read head element,  11   a  and  11   b  denote lead conductors for the MR read head element, one ends of which are connected to the respective pads  10   a  and  10   b ,  12   a  and  12   b  denote contacts for the MR read head element, connected to the other ends of the respective lead conductors  11   a  and  11   b ,  13   a  and  13   b  denote MR lead electrodes connected to the respective contacts  12   a  and  12   b ,  14  denotes an MR film both end portions of which are connected to the respective MR lead electrodes  13   a  and  13   b ,  15   a  and  15   b  denote connection terminals or pads for the inductive write head element,  16   a  and  16   b  denote lead conductors for the inductive write head element, one ends of which are connected to the respective pads  15   a  and  15   b ,  17  denotes a first layer coil conductor, one end of which is connected to the other end of the lead conductor  16   a ,  18  denotes a second layer coil conductor, one end of which is connected to the other end of the lead conductor  16   b ,  19  denotes a coil connection part for connecting the first layer coil conductor  17  and the second layer coil conductor  18  with each other,  20  denotes a coil insulation layer (a first coil insulation layer  20   a , a second coil insulation layer  20   b  and a third coil insulation layer  20   c ) surrounding the first and second layer coil conductors  17  and  18 ,  21  denotes a lower shield layer,  22  denotes an upper shield layer doubling as a lower core layer (a first upper shield layer  22   a  and a second upper shield layer doubling as a lower core layer  22   b ),  23  denotes an upper core layer,  24  denotes a back gap part for magnetically connecting the lower core layer  22  and the upper core layer  23  in order to form a magnetic path, and  85  denotes a thermal diffusion layer laminated on the coil insulation layer  20  at the lateral outside region of the upper core layer  23  so as to directly contact with the first layer coil conductor  17  or to constitute a part of the first layer coil conductor  17 , respectively. In modification, the thermal diffusion layer  85  may be formed so as to directly contact with the second layer coil conductor  18  or to constitute a part of the second layer coil conductor  18 .  
         [0070]    [0070]FIGS. 9 a  to  9   g  schematically illustrate an example of manufacturing processes of the thin-film magnetic head in this embodiment, and FIGS. 10 a  to  10   g  illustrate sections along an A-A line of FIGS. 9 a  to  9   g , respectively. Hereinafter, the manufacturing processes of the thin-film magnetic head in this embodiment will be described with reference to these figures.  
         [0071]    First, an under film and other necessary film are deposited on a wafer. Next, as shown in FIGS. 9 a  and  9   a , the lower shield layer  21  is formed on the under film, an insulation layer is deposited thereon, and then its surface is flattened by executing CMP.  
         [0072]    Then, as shown in FIGS. 9 b  and  10   b , a first read gap layer  26   a  is formed thereon, the MR film  14  and the MR lead electrodes  13   a  and  13   b  are formed, a second read gap layer  26   b  is formed thereon, and thereafter the first upper shield layer  22   a  is formed thereon.  
         [0073]    Then, as shown in FIGS. 9 c  and  10   c , the second upper shield layer doubling as the lower core layer  22   b  is formed on the first upper shield layer  22   a , an insulation layer is deposited thereon, and then its surface is flattened by executing CMP.  
         [0074]    Thereafter, as shown in FIGS. 9 d  and  10   d , the first coil insulation layer  20   a  is deposited, the first layer coil conductor  17  and the coil connection part  19  are formed thereon. In the same process of forming the first layer coil conductor  17  and the coil connection part  19 , the thermal diffusion layer  85  is formed on the first coil insulation layer  20   a  at the lateral outside region of the upper core layer  23  so as to directly contact with the first layer coil conductor  17  or to constitute a part of the first layer coil conductor  17 . Then, the second coil insulation layer  20   b  is formed to cover the first layer coil conductor  17  and the thermal diffusion layer  85 .  
         [0075]    The thermal diffusion layer  85  is made of a material with a higher thermal conductivity than that of a protection layer of Al 2 O 3 . Preferably, the thermal diffusion layer  85  is made of the same material as the coil conductor such as Cu for example in order to simplify the manufacturing process. However, as for the thermal diffusion layer  85 , any material selected from Au, Ag, Si, Zn, Al, Ir, Cd, Sb, W, Ta, Fe, Pb, Ni, Pt, Pd, Mg and Mo or an alloy containing at least one of these materials can be used. It is also preferred to use as the thermal diffusion layer  85  a material with a lower thermal expansion coefficient than that of a protection layer of Al 2 O 3 .  
         [0076]    Then, as shown in FIGS. 9 e  and  10   e , the second layer coil conductor  18  and the coil connection part  19  are formed on the second coil insulation layer  20   b , and the third coil insulation layer  20   c  is formed thereon. The pads  10   a ,  10   b ,  15   a  and  15   b  and the lead conductors  11   a ,  11   b ,  16   a  and  16   b  are formed in this stage. In the same process of forming the second layer coil conductor  18  and the coil connection part  19 , the thermal diffusion layer  85  may be formed at the lateral outside region of the upper core layer  23  so as to directly contact with the second layer coil conductor  18  or to constitute a part of the second layer coil conductor  18 . Namely, the thermal diffusion layer  85  may be formed in the same process of forming the first layer coil conductor  17  or in the same process of forming the second layer coil conductor  18 . In further modification, one thermal diffusion layer may be formed in the same process of forming the first layer coil conductor  17 , and the other thermal diffusion layer may be formed in the same process of forming the second layer coil conductor  18 .  
         [0077]    Then, as shown in FIGS. 9 f  and  10   f , the upper core layer  23  is formed on the third coil insulation layer  20   c  at its front side (ABS side) region.  
         [0078]    Thereafter, as shown in FIGS. 9 g  and  10   g , under films for bumps are formed on the pads  10   a ,  10   b ,  15   a  and  15   b , and then bumps are formed on the under films.  
         [0079]    Although it is not shown in the figures, thereafter, the protection layer such as Al 2 O 3  is formed on the upper core layer  23  and the third coil insulation layer  20   c.    
         [0080]    As aforementioned, according to this embodiment, since the thermal diffusion layer  85  is formed at the lateral outside region of the upper core layer  23 , heat-radiation effect can be expected without any deleterious effect on the magnetic performance of the inductive write head element. Also, since the thermal diffusion layer  85  is formed so as to directly contact with the first and/or second layer coil conductors, or to constitute a part of the first and/or second layer coil conductors, sufficient heat-radiation effect can be obtained. As a result, not only contact of the magnetic head with a magnetic medium in operation due to the heat expansion toward the ABS but also disconnection of the coil conductors  17  and  18  themselves, caused by heating of the coil conductors  17  and  18 , can be effectively prevented.  
         [0081]    Furthermore, according to this embodiment, the thermal diffusion layer  85  is formed in the same forming process of the coil conductor, no additional process is required.  
         [0082]    It should be noted that each layer except for the thermal diffusion layer  85  and the protection layer can be made of any material generally used in this technical field, and can be formed (deposited, patterned) by using any method known in this field.  
         [0083]    Although in this embodiment the upper shield layer doubling as the lower core layer  22  is formed in the two layer structure of the first upper shield layer  22   a  and the second upper shield layer doubling as the lower core layer  22   b , it is possible to form it in a single layer structure. In this embodiment the coil conductor is formed also in the two layer structure of the first layer coil conductor  17  and the second layer coil conductor  18 . Nevertheless, the coil conductor may be formed in a multilayer structure of more than two layers or in a single layer structure.  
         [0084]    It is apparent that the MR read head element in the composite thin-film magnetic head may be an anisotropic magnetoresistive effect (AMR) read head element, a giant magnetoresistive effect (GMR) read head element including both a current in plane (CIP) type GMR element in which current flows along layer planes and a current perpendicular to plane (CPP) type GMR element in which current flows perpendicular to layer planes, or a tunnel magnetoresistive effect (TMR) read head element.  
         [0085]    It will be also noted that the present invention is not limited to a composite thin-film magnetic head provided with an inductive write head element and an MR read head element but can be applied to a thin-film magnetic head provided with only an inductive write head element or an inductive read/write head element.  
         [0086]    Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.