Abstract:
The method of manufacturing a magnetic head is capable of preventing element sections from being damaged by static electricity and which is capable of keeping prescribed characteristics of the magnetic head. The method of the present invention comprises the steps of: forming film layers on a surface of a substrate; etching the film layers to form into prescribed patterns; and forming an element section having prescribed characteristics, wherein a specific section of the substrate, in which the element section is formed, is enclosed by electric conductive film.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a method of manufacturing a magnetic head, and more precisely relates to a method of manufacturing a magnetic head, which is capable of preventing an element or elements from being damaged by static electricity which is generated while manufacturing the magnetic head. 
     The magnetic heads for magnetic disc drive units are manufactured by the steps of: forming magnetizable film layers and non-magnetizable film layers on a surface of a ceramic substrate, which is formed into a wafer; and patterning the film layers. To execute the patterning step, first a resist layer is formed on the film layers and formed into prescribed patterns, then the film layers, which are masked with the patterned resist layer, are patterned by ion milling, sputtering, etc. 
     While executing treatments of the film layers, e.g., trimming by ion milling, pattern etching by dry etching, cleaning the surface of the film layers by sputter-etching, static electricity is charged on the surface of the film layers; the static electricity damages sensing parts of element sections of the magnetic heads and badly influences characteristics of the magnetic heads. To solve these disadvantages, an ion milling device neutralizes ions so as not to charge the static electricity in a work piece. 
     In the conventional method of manufacturing the magnetic head, damaging the element sections by static electricity was not a serious problem. However, in the case of spin valve heads capable of writing data with high density, the element sections are apt to be damaged by static electricity, so it is necessary to protect the element sections from the static electricity. In conventional magnetic heads, about 20 [V] of static electricity damages the element sections; in spin valve heads, about 5 [V] of static electricity damages the element sections. 
     In some cases, the film layers are etched to form into a plurality of isolated islands, so influences of static electricity must be prevented. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a method of manufacturing a magnetic head which is capable of preventing the element sections from being damaged by static electricity and which is capable of keeping prescribed characteristics of the magnetic head. Another object is to provide a method of manufacturing a magnetic head, which is capable of highly improving yield of manufacturing. 
     To achieve the objects, the method of manufacturing the magnetic head comprises the steps of: forming film layers on a surface of a substrate; etching the film layers to form into prescribed patterns; and forming an element section having prescribed characteristics, wherein a specific section of the substrate, in which the element section is formed, is enclosed by electric conductive film. 
     In the method, an electric conductive layer, in which a sensing part of the element section is formed, may be formed on the substrate, then the specific section is etched to form the element section. 
     In the method, an upper shielding layer may be formed on the sensing part of the element section after the sensing part is formed, then the electric conductive layer around the element section may be removed. 
     Another method of manufacturing the magnetic head comprises the steps of: forming film layers on a surface of a substrate; etching the film layers into prescribed patterns; and forming a plurality of element sections having prescribed characteristics, wherein cable patterns, which are connected to terminals of the element sections or coils, are mutually connected for further treatment. 
     In the method, write-heads of the element sections may be formed by the steps of: forming a write-gap layer; an electric conductive film, which is formed into the cable patterns, is formed on the write-gap layer; and etching the electric conductive film to mutually connect the cable patterns. 
     In the methods, each of the etching may be executed by ion milling. 
     In each of the methods, the electric conductive film may be electrically grounded for further treatment. 
     In the method of the present invention, the specific section of the substrate, in which the element section is formed, is enclosed by electric conductive film, then the film layers are etched by ion milling or piled by sputtering. During the manufacturing process, electric current caused by static electricity is prevented from passing through the sensing part of the element section, so that damaging the element sections can be prevented and the yield of manufacturing can be highly improved. 
     The electric conductive film is left when the electric conductive layer and the shielding layer of the sensing part are etched, so the magnetic head can be manufactured without sharply changing the conventional method. 
     By connecting the electric conductive film to the ground or by mutually connecting the terminals of the element sections, damaging the element sections can be effectively prevented. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the present invention will now be described by way of examples and with reference to the accompanying drawings, in which: 
     FIG. 1 is a plan view showing means for protecting elements from the static electricity; 
     FIG. 2A is a plan view of a substrate on which film layers are formed; 
     FIG. 2B is a sectional view of the substrate on which the film layers are formed; 
     FIG. 3A is a plan view of the substrate on which terminals are formed; 
     FIG. 3B is a sectional view of the substrate on which the terminals are formed; 
     FIG. 4A is a plan view of the substrate in which a peripheral of the terminals is rectangularly machined; 
     FIG. 4B is a sectional view of the substrate in which the peripheral of the terminals is rectangularly machined; 
     FIG. 5 is a sectional view of an element section on which a second gap layer is formed; 
     FIG. 6A is a plan view of the substrate on which upper shielding layers are formed; 
     FIG. 6B is a sectional view of the substrate on which the upper shielding layers are formed; 
     FIG. 7A is a plan view of the substrate from which disused parts of a plating base are removed; 
     FIG. 7B is a plan view of the substrate from which the disused parts of the plating base are removed; 
     FIG. 8A is a plan view of the substrate from which the upper shielding layers and a free layer of parts other than the element sections are removed; 
     FIG. 8B is a plan view of the substrate from which the upper shielding layers and the free layer of parts other than the element sections are removed; 
     FIG. 9A is a plan view of the substrate in which a write-gap layer and a coil insulating layer are formed on surfaces of the element sections; 
     FIG. 9B is a sectional view of the substrate in which the write-gap layer and the coil insulating layer are formed on the surfaces of the element sections; 
     FIG. 10 is a sectional view of the substrate in which the plating base is formed on a surface of the coil insulating layer; 
     FIG. 11 is an explanation view showing a planar arrangement of the element section, vertical terminals, cable patterns and the electric conductive film; 
     FIG. 12 is an explanation view showing another example of the electric conductive film; and 
     FIG. 13 is a sectional view of a magnetic head. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
     FIG. 1 is a plan view showing means for protecting elements from static electricity. A reference symbol  10  stands for a wafer-shaped substrate on which a plurality of film layers are formed to manufacture the magnetic heads; reference symbols  12  stand for element sections formed on the substrate  10 ; a reference symbol  14  stands for an electric conductive film, which is formed on a surface of the substrate  10  and which encloses the element sections  12 . The electric conductive film  14  is integrated with the substrate  10  and is electrically grounded. 
     The electric conductive film  14  prevents electric current, which is caused by static electricity when the ion milling or the spattering is executed, from passing through the element sections, so that the elements can be protected. 
     The electric conductive film  14  may be formed in a step of forming the film layers for the elements. Further, a magnetizable layer and shielding layers, which are electric conductive film layers for the elements, may act as the electric conductive film  14 . In this case, the protecting means can be produced easily. 
     The method of manufacturing the magnetic heads, with the protecting means for each step, will be explained. 
     FIG. 2A is a plan view of the substrate  10  on which the MR film layer is formed; and FIG. 2B is a sectional view thereof. In FIG. 2B, a reference symbol  16  stands for a protecting layer formed on the surface of the substrate  10 ; a reference symbol  18  stands for a biasing layer, which is the magnetizable layer; a reference symbol  20  stands for a first gap layer, which is a non-magnetizable layer; a reference symbol  22  stands for a free layer, which is an electrically conductive magnetizable layer. The magnetic head of the present embodiment is a three-layered head, but the method can be applied to other types of magnetic heads, e.g., a spin valve head, which have other structures of the film layers. 
     In the three-layered substrate, terminal sections  24  (see FIGS. 3A and 3B) are formed by trimming the free layer  22 . The trimming is executed by ion milling. FIG. 3A is a plan view of the substrate on which the terminals  24  are formed; FIG. 3B is a sectional view thereof. The terminal sections  24  are formed by the steps of: forming a resist layer on a surface of the free layer  22 ; exposing parts in which the terminal sections  24  will be formed; removing the free layer  22  in the parts for the terminal sections  24  by ion milling; the sputtering. Since the free layer  22  is wholly electrically connected to the substrate  10 , the problems of static electricity are not caused during the ion milling. 
     Next, a peripheral of each element section is rectangularly machined. FIG. 4A is a plan view of one element section in which a peripheral of the terminals  24  is rectangularly machined; FIG. 4B is a sectional view thereof. In a section “B”, the free layer  22  is removed and the first gap layer  20  is exposed. FIG. 4B is the sectional view taken along a line A—A in FIG.  4 A. In the step of the ion milling, the method is characterized in that the terminal sections  24  and the sensing part  28  are covered with the resist film during the ion milling, and the section “B” and its peripheral are also covered with the resist film so as to leave the free layer  22 . The free layer  22  is the electric conductive layer, and the free layer  22  left is formed like a frame and is electrically grounded, so that the bad influences of static electricity can be avoided during the ion milling. 
     Next, a second gap layer  30  (see FIG.  5 ), which is a non-magnetizable layer, is formed. FIG. 5 is a sectional view of the substrate on which the second gap layer  30  is formed. The second gap layer  30  is an alumina film layer. First, the alumina film layer is wholly formed on the surface of the substrate  10 , then the alumina film layer, which is not located in the section “B”, is removed by ion milling, so that the second gap layer  30  is left in the section “B” only. To leave the second gap layer  30  in the section “B”, the section “B” is covered with the resist layer, but other sections are exposed during the ion milling. The free layer  22  is electrically grounded, so the ion milling can be executed without the bad influences of static electricity. 
     Next, upper shielding layers are formed on surfaces of the element sections. The upper shielding layers are formed by plating. In the state shown in FIG. 5, a plating base  32  (see FIG. 6B) is formed to cover each element section and its peripheral. The plating base  32  is formed by plating or sputtering. 
     After the plating base  32  is formed as a layer for supplying electricity, the upper shielding layers  34  are formed by plating. In the present embodiment, the upper shielding layers are made of permalloy. FIG. 6A is a plan view of the substrate on which the upper shielding layers  34  are formed; FIG. 6B is a sectional view thereof. One section of upper shielding layer  34  covers over ends of the terminal sections  24  and the sensing part  28 ; and another section of upper shielding layer  34  is located outside of the section “B”. 
     The upper shielding layers  34  are formed by the steps of: masking the surface of the substrate with a resist film, which exposes the parts to be plated; and executing emboss plating. A reference symbol  34   a  stands for a connecting part, which connects cable patterns with the terminal section  24 . In the connecting parts  34   a,  the second gap layers  30  have been previously removed to conductive electricity, then the plating base  32  and the upper shielding layers  34  are formed. 
     Next, disused parts of the plating base  32  are removed by ion milling. The disused parts of the plating base  32  are shown in FIG.  7 A. Namely, the parts of the plating base  32  which are exposed in the section “B” are the disused parts to be removed. FIG. 7B is a sectional view in which the disused parts of the plating base  32  have been removed. In this step too, the free layer  22  is electrically grounded, so the bad influences of static electricity can be avoided. 
     After the upper shielding layers  34  are formed, parts of the upper shielding layers  34 , which do not correspond to the element sections, and the free layer  22  are removed by chemical etching. 
     FIGS. 8A and 8B show a state in which the element section is left on the substrate  10 . In the peripheral of the element section, the first gap layer  20  is exposed. One element section is shown in the drawing, but there are many element sections that are metrically arranged in the actual substrate  10 . 
     In the element section, the second gap layer  30 , the plating layer  32  and the upper shielding layer  34  are piled, in this order, on each of the terminal sections  24  and the sensing part  28 . They constitute a read-section of the magnetic head. 
     The free layer  22 , which is the electric conductive layer, is left on and around the element sections until the upper shielding layers  34  are formed or the read-section is constituted. The free layer  22  is formed in one body and is electrically grounded, so that static electricity never badly influences the element sections, especially the sensing parts  28 , while executing the sputtering, etc. 
     After the upper shielding layers  34  are formed, a write-head is formed thereon. In the steps of forming the write-head, the ion milling, etc. are executed, so a counter-measure to the static electricity is required. 
     In FIG. 9, a write-gap layer  36  and a coil insulating layer  38  are formed on the element section, which is shown in FIG.  8 . The write-gap layer  36  is an alumina film layer; the coil insulating layer  38  is a resist layer. 
     A coil  42  is formed on the coil insulating layer  38 . The coil  42  is formed by plating, so first a plating base  40  is formed on the coil insulating layer  38  by copper plating or copper sputtering. FIG. 10 shows a state in which the plating base  40  is formed on the surface of the coil insulating layer  38  and the coil  42  is formed thereon. Note that, the plating base  40  acts as a layer for supplying electricity for forming not only the coil  42  but also the vertical terminals (write-terminals and read-terminals), which will be formed by plating. The plating base  40  is wholly formed on the surface of the substrate. 
     The coil  42  is formed by the steps of: forming the resist layer on the substrate; forming a resist pattern, which exposes the plating base  40  in the form of a pattern of the coil  42 ; and executing emboss plating. 
     The plating base  40  between coil patterns is removed, by ion milling, in the following step, then the plating base  40  is used as the electric supplying layer and the vertical terminals are plated. In FIG. 11, reference symbols  44  stand for the write-terminals of the vertical terminals; reference symbols  46  stand for the read-terminals thereof. The vertical terminals  44  and  46  are formed by the steps of: forming the resist layer, which exposes parts of forming the vertical terminals  44  and  46 , on the surface of the plating base  40 ; and executing emboss plating. 
     Cable patterns  48 , which electrically connect the vertical terminals  44  and  46  with the terminal sections  24 , are formed by ion milling the plating base  40 . 
     While executing the ion milling the plating base  40 , an electric conductive film  50  is also formed so as to prevent the bad influences caused by static electricity. 
     The element section, the coil  42 , the vertical terminals  44  and  46 , the cable patterns  48 , etc., which should be left on the substrate, and parts of the electric conductive layer  50 , which should be left as shown in FIGS. 11, are covered with the resist, then ion milling is executed to form prescribed patterns on the substrate  10 . 
     The electric conductive layer  50  short-circuits the terminals and encloses each element section. The electric conductive layer  50  is electrically grounded. Since the electric conductive layer  50  short-circuits the terminals, no electric current passes through the element sections during the ion milling. While ion milling, the plating base  40  between coil patterns is removed to complete the coil  42 . 
     FIG. 13 shows a state in which an upper insulating layer  52  is formed on the surface of the element section after the coil  42 , the vertical terminals  44  and  46  and the cable patterns  48  are formed by ion milling. Afterwards each element is separated from the substrate  10  to complete the magnetic head. In FIG. 13, the electric conductive film  50  is formed on the surface of the substrate  10 , so the elements should be separated so as not to short-circuit the terminals by the electric conductive film  50 . 
     In the case of measuring static characteristics of the magnetic heads, first the short-circuited parts are cut by scribing the electric conductive film  50  and the static characteristics are measured, then the elements or the magnetic heads are completely separated by cutting the substrate  10 . 
     Another embodiment of the electric conductive film  50  for preventing bad influences caused by the static electricity is shown in FIG.  12 . In this embodiment, the write-terminals  44  and  44  and the read-terminals  46  and  46  are respectively short-circuited by the electric conductive film  50 . Since the terminals are short-circuited by the electric conductive film  50 , no electric current caused by static electricity passes through the sensing parts  28 , so this structure can be an effective countermeasure to static electricity. 
     In the above described embodiments, the sensing part  28  includes the biasing layer  18 , the first gap layer  20  and the free layer  20 , but the structure of the sensing part  28  is not limited to said structure. In the case of a sensing part of a multi-layered spin valve head, for example, the shielding layer, which is the electric conductive layer, may be used as the electric conductive layer for preventing the bad influences of static electricity, so that the magnetic heads can be manufactured with an effective countermeasure to static electricity. 
     The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and ranging of equivalency of the claims are therefore intended to be embraced therein.