JP4664085B2 - Method for measuring insulation resistance in thin film magnetic head and method for manufacturing thin film magnetic head - Google Patents

Description

  The present invention relates to the manufacture of a thin film magnetic head, and more particularly to a method for measuring insulation resistance in the manufacturing process of a thin film magnetic head.

  As a thin film magnetic head, a thin film magnetic head having a composite structure in which a reproducing unit having a magnetoresistive effect element (MR element) for reading and a recording unit having an inductive magnetic transducer for writing are joined in close proximity is widely used. It is used. As the MR element constituting the reproducing unit, a device using a spin valve film (hereinafter referred to as an SV film) is mainly used. On the other hand, a thin-film magnetic head using a ferromagnetic tunnel junction film (hereinafter referred to as a TMR film) as an MR element can expect a resistance change rate more than twice that of a thin-film magnetic head using an SV film. Has been done.

  MR elements are roughly classified into two structures based on the difference in the direction in which the sense current flows. One is called a CIP (Current In Plane) structure in which a sense current flows parallel to the film surface, and the other is a CPP (Current Perpendicular to Plane) structure in which a sense current flows perpendicular to the film surface. Called. Since the CPP structure can use the magnetic shield itself as an electrode, a short circuit (insulation failure) between the magnetic shield and the element, which is a problem in narrowing the read gap of the CIP structure, does not occur essentially. Therefore, the CPP structure is very advantageous for increasing the recording density.

  Since the TMR film basically has a CPP structure, the above-described advantages can be obtained. Also in the SV film, in order to secure the advantages of the above-described CPP structure, the CIP structure, which has been widely used in the past, is being converted to the CPP structure. For example, a multilayer structure such as a specular type or a dual type is an example.

In the CPP structure, the lower shield layer and the first upper shield layer stacked so as to sandwich the MR element from both sides are also used as electrodes for supplying a sense current. The lower shield film is provided on a substrate made of Al ₂ O ₃ .TiC (Altic) having excellent wear resistance. Altic has a higher electrical conductivity than Al ₂ O ₃ (alumina). A first insulating layer (underlayer) is provided on the upper surface of the substrate, and a lower shield layer is formed thereon. Then, the second insulating layer is interposed between the lower shield layer and the first upper shield layer, and the MR element is disposed inside the second insulating layer.

  A third insulating layer is provided on the first upper shield layer, and a recording unit is provided on the third insulating layer. The recording unit has a coil, a magnetic circuit, and a recording gap. The coil is supported by being insulated from the surroundings by an organic material or an insulating layer made of an organic material. The magnetic circuit guides the magnetic flux generated by the current flowing in the coil, and is supported by the lower magnetic pole / second upper shield layer facing the first upper shield layer via the third insulating layer, and the insulating layer. And an upper magnetic pole layer that faces the lower magnetic pole and the second upper shield layer and is magnetically coupled to the lower magnetic pole and the second upper shield layer at a position away from the surface facing the recording medium. . The lower magnetic pole / second upper shield layer and the upper magnetic pole layer each have a magnetic pole portion facing each other on the surface facing the recording medium, and the recording gap is disposed between these magnetic pole portions.

In the above-described thin film magnetic head, it is necessary to maintain insulation between the upper magnetic pole layer and the coil in the recording portion and insulation between the shield layer and the MR element in the reproducing portion. Therefore, in the manufacturing process of the thin film magnetic head, an insulation performance inspection is generally performed. For example, Patent Document 1 relates to an insulation performance test in a recording unit. When an upper magnetic pole layer is formed, a magnetic pole terminal portion electrically connected to the upper magnetic pole layer is formed, and the magnetic pole terminal portion and an electrode for a coil are formed. It is disclosed that a predetermined voltage is applied between a pad and a probe to detect the presence of insulation by detecting a current flowing between the magnetic pole terminal portion and the electrode pad. Further, in Patent Document 2, regarding the insulation performance inspection in the reproducing unit, a measurement electrode pad electrically connected to the lower shield layer and the upper shield layer is provided separately from the MR element electrode pad, and a plurality of thin films It has been disclosed that a plurality of thin film magnetic heads are simultaneously inspected for insulation performance of a reproducing unit on a wafer on which a magnetic head is formed.
JP-A-6-333213 JP 2001-56912 A

  In the conventional thin film magnetic head having the CPP structure, the magnetic layers such as the shield layer and the pole layer are magnetically and electrically insulated from the substrate. When friction occurs between them, the magnetic layer is charged. When electric charges are accumulated in the magnetic layer due to charging and a potential difference exceeding the withstand voltage with the recording medium is generated, a discharge occurs between the thin film magnetic head and the recording medium. In particular, when a discharge occurs in the magnetic layer (upper shield layer-lower shield layer) in the reproducing portion, the MR element is destroyed in the worst case.

  In order to prevent the above-described problems caused by charging, it is necessary to release charges accumulated in the magnetic layer to the substrate. Therefore, it is conceivable to provide a via plug that penetrates the underlayer and connect the magnetic layer to the substrate through the via plug.

  However, it has been found that in the thin film magnetic head in which the magnetic layer is electrically connected to the substrate, a new problem may occur when the insulation is evaluated in the same manner as in the past. The problem occurs when the insulation performance test is simultaneously performed on a plurality of thin film magnetic heads as disclosed in the cited document 2. The insulation performance can be specifically measured by measuring the insulation resistance. The insulation resistance is measured by measuring the resistance value between the electrode pad for measurement electrically connected to the magnetic layer and the electrode pad for the coil in the recording unit, and the shield in the reproducing unit. The measurement is performed by measuring the resistance value between the electrode pad for measurement electrically connected to the layer and the electrode pad for the MR element. The resistance value is measured by applying a predetermined voltage between the two electrode pads. At this time, the resistance value may not be accurately measured depending on how the voltage is applied.

  The object of the present invention is to simultaneously measure the insulation resistance of a plurality of elements when measuring the insulation resistance of the elements provided in the thin film magnetic head in the manufacturing process of the thin film magnetic head in which the substrate and the magnetic layer are electrically connected. Even when measuring, it is to obtain an accurate measurement result.

In order to achieve the above object, a method for measuring an insulation resistance according to the present invention is a method for measuring an insulation resistance of an inductive magnetic transducer element in a manufacturing process of a thin film magnetic head having an inductive magnetic transducer element. A step of preparing a head element assembly having a plurality of inductive magnetic transducers formed thereon, and a step of measuring an insulation resistance. Inductive magnetic transducer includes a pair of magnetic pole layer connected with the substrate electrically with the magnetically coupled with opposite other end with the gap layer at one side, magnetic between magnetic pole layer It comprises a coil which is supported by being insulated from the electrode layer. Then, the magnetic pole layer side plus the coil side as a minus, by applying a DC current simultaneously to at least two of the inductive magnetic transducer, measures the insulation resistance between the magnetic pole layer and the coil . In the process of measuring the insulation resistance, each inductive magnetic transducer is connected in parallel to a common positive potential, and in each inductive magnetic transducer, the magnetic pole layer and the coil are connected in series with the magnetic pole layer as the common positive potential side. Forming an integrated circuit.

The method for measuring insulation resistance of the present invention is a method for measuring insulation resistance of a magnetoresistive effect element in a manufacturing process of a thin film magnetic head having a head element equipped with the magnetoresistive effect element, and a head element assembly is prepared. And a step of measuring insulation resistance. The head element assembly includes a substrate, a plurality of magnetoresistive elements formed on the substrate, and first and second shield layers that are insulated from the magnetoresistive elements and sandwich each of the magnetoresistive elements. And at least one of the first and second shield layers is electrically connected to the substrate. Then, a DC voltage is simultaneously applied to at least two of the magnetoresistive elements, with the shield layer electrically connected to the substrate being positive and the magnetoresistive element side being negative, The insulation resistance between the connected shield layer and the magnetoresistive effect element is measured. The step of measuring the insulation resistance is that the head elements are connected in parallel to a common positive potential, and in each head element, one of the shield layers electrically connected to the substrate is set as a common positive potential side. And forming a circuit in which the magnetoresistive effect element is connected in series.

  In the measurement of insulation resistance according to the present invention, a plurality of elements (inductive magnetic transducer elements, magnetoresistive elements) are formed on a substrate, and the magnetic layers (shield layers) associated with these elements are electrically connected to the substrate. Insulation resistance of each element is measured in the state of the head element aggregates connected to each other. In measuring the insulation resistance of each element, a DC voltage is simultaneously applied to a plurality of elements with the magnetic layer (shield layer) side electrically connected to the substrate as a plus. In this way, by defining the polarity at the time of applying the DC voltage, it is possible to prevent a sneak current flowing to another element through the substrate, so that an accurate insulation resistance is measured.

Method of manufacturing a thin film magnetic head of the present invention, inductive method for manufacturing a magnetic transducer a thin film magnetic head having an element, on a substrate, magnetic pole layer and electrical magnetic pole layer and the substrate connected a coil Manufacturing a head element assembly formed with a plurality of inductive magnetic transducers, measuring an insulation resistance of the induction magnetic transducer of the head element assembly, and a head element assembly having measured insulation resistance Dividing the body into inductive magnetic transducers. The step of measuring the insulation resistance, plus magnetic pole layer side, the coil side as a minus, and simultaneously applying a DC voltage to at least two of the inductive magnetic transducer, a magnetic pole layer and the coil look including the step of measuring the insulation resistance between the pole layer pole layer as a common positive potential side in the inductive magnetic transducer with the inductive magnetic transducer is connected in parallel to a common positive potential Forming a circuit connected in series with the coil .

The method for manufacturing a thin film magnetic head according to the present invention is a method for manufacturing a thin film magnetic head having a head element provided with a magnetoresistive effect element, wherein the magnetoresistive effect element is provided on the substrate. A head element assembly having first and second shield layers corresponding to the above, wherein at least one of the first and second shield layers is electrically connected to the substrate, and a head element assembly The step of measuring the insulation resistance of the magnetoresistive effect element, and the step of dividing the head element assembly for which the insulation resistance has been measured for each magnetoresistive effect element. The step of measuring the insulation resistance is to apply a DC voltage simultaneously to at least two of the magnetoresistive effect elements, with the shield layer side electrically connected to the substrate being positive and the magnetoresistive effect element side being negative. and, viewed including the step of measuring the insulation resistance between the substrate and electrically connected to the shield layer and the magnetoresistive element, together with the head element is connected in parallel to a common positive potential, in each head element Includes forming a circuit in which the shield layer and the magnetoresistive element are connected in series with any one of the shield layers electrically connected to the substrate as a common positive potential side .

  As described above, in the method for manufacturing a thin film magnetic head of the present invention, the above-described method for determining the insulation resistance of the present invention is applied to the measurement of the insulation resistance of an element such as an inductive magnetic transducer or a magnetoresistive element. This provides a thin film magnetic head whose insulation resistance is accurately measured.

  According to the present invention, it is possible to accurately measure the insulation resistance of an element when manufacturing a highly reliable thin film magnetic head in which a problem due to charging of a magnetic layer is prevented. As a result, it is possible to provide a thin film magnetic head with stable quality by preventing outflow of defective insulation.

  FIG. 1 conceptually shows a cross-sectional view of the main part of a thin film magnetic head according to an embodiment of the present invention.

  The thin film magnetic head 1 according to this embodiment includes a substrate 11, a reproducing unit 2 having an MR element 14 for reading from a recording medium (not shown) formed on the substrate 11, and inductive magnetic conversion for writing. And a recording unit 3 having elements.

  The substrate 11 is made of Altic. Altic is superior in wear resistance and lubricity as compared with alumina, but has high conductivity. Therefore, the base layer 12 made of alumina is formed on the upper surface of the substrate 11, and the reproducing unit 2 and the recording unit 3 are laminated thereon.

  On the base layer 12, a lower shield layer 13 made of a magnetic material such as permalloy (NiFe) is formed. An MR element 14 is formed on the lower shield layer 13 at the end on the medium facing surface S side with one end thereof exposed to the medium facing surface S. As the MR element 14, various elements using a magnetosensitive film exhibiting a magnetoresistive effect, such as an AMR (anisotropic magnetic effect) element, a GMR (giant magnetoresistive effect) element, and a TMR (tunnel magnetoresistive effect) element are used. be able to. A first upper shield layer 15 made of a magnetic material such as permalloy is formed on the MR element 14. The MR element 14 is insulated from the lower shield layer 13 and the first upper shield layer 15 by an insulating layer 16a. The lower shield layer 13, the MR element 14, and the first upper shield layer 15 constitute the reproducing unit 2.

  A second upper shield layer 17 made of a magnetic material such as permalloy or CoNiFe that can be formed by a plating method is formed on the first upper shield layer 15 via an insulating layer 16b. The second upper shield layer 17 has a function as the lower magnetic pole layer of the recording unit 3 in addition to the function as the upper shield layer of the MR element 14.

  An upper magnetic pole layer 19 is formed on the second upper shield layer 17 via a recording gap layer 18 for insulation. The recording gap layer 18 is formed at the end on the medium facing surface S side, with one end exposed on the medium facing surface S. That is, the second upper shield layer 17 and the upper magnetic pole layer 19 are opposed to each other via the recording gap layer 18 at one end thereof. As the material of the recording gap layer 18, for example, a nonmagnetic metal material that can be formed by sputtering, such as Ru or alumina, is used. As the material of the upper magnetic pole layer 19, for example, a magnetic material that can be formed by a plating method such as permalloy or CoNiFe is used. The second upper shield layer (lower magnetic pole layer) 17 and the upper magnetic pole layer 19 are magnetically connected by the connecting portion 21 at the end away from the medium facing surface S, and form a single magnetic circuit as a whole.

  Between the second upper shield layer 17 and the upper magnetic pole layer 19, a coil 20 made of a conductive material such as copper is formed between the medium facing surface S and the connection portion 21. The coil 20 supplies magnetic flux to the second upper shield layer 17 and the upper magnetic pole layer 19, and is formed in two layers in a shape that circulates around the connection portion 21 so as to have a planar spiral shape. The coil 20 is insulated from the surroundings by an insulating layer. The number of turns of the coil 20 is arbitrary. In the present embodiment, the two-layer coil 20 is shown. However, the present invention is not limited to this, and may be one layer or three or more layers.

  The inductive magnetic transducer includes these second upper shield layer 17, upper magnetic pole layer 19 and coil 20.

  The overcoat layer 22 is provided so as to cover the upper magnetic pole layer 19 and protects the above-described structure. As a material of the overcoat layer 22, an insulating material such as alumina is used.

  On the substrate 11, a first via plug 35 a penetrating the base layer 12 is provided. The first via plug 35 a is electrically connected to the lower shield layer 13 through the wiring 37. As the material of the first via plug 35a, the same material as that of the lower shield layer 13 can be used. Between the lower shield layer 13 and the lower magnetic pole / second upper shield layer 17, second via plugs 35 b penetrating the insulating layers 16 a and 16 b and the first upper shield layer 15 are provided. The lower shield layer 13, the first upper shield layer 15, and the lower magnetic pole / second upper shield layer 17 are electrically connected by a second via plug 35b.

  As described above, in the present embodiment, the lower shield layer 13 and the first upper shield layer 15 are electrically connected to the substrate 11 via the first via plug 35a. Accordingly, charging of each of these shield layers can be prevented, and in particular, destruction of the MR element 14 due to discharge between the lower shield layer 13 and the first upper shield layer 15 can be effectively prevented.

  Furthermore, in the present embodiment, the first upper shield layer 15 and the lower magnetic pole / second upper shield layer 17 are electrically connected by the second via plug 35b. A parasitic capacitance is generated between the lower magnetic pole / second upper shield layer 17 and the first upper shield layer 15 by using the insulating layer 16b as a capacitive layer, and between the lower shield layer 13 and the substrate 11, a lower capacitance is generated. Parasitic capacitance is generated with the formation 12 as a capacitive layer. If these parasitic capacitances are different from each other, external noise easily enters from the substrate 11 side, causing deterioration of the MR element 14 and an error. On the other hand, in this embodiment, since the lower magnetic pole and second upper shield layer 17 is also electrically connected to the substrate 11, the first upper shield layer 15 and the lower portion viewed from the first upper shield layer 15. The voltage between the magnetic pole-cum-second upper shield layer 17 and the voltage between the substrate 11 and the lower shield layer 13 viewed from the lower shield layer 13 are substantially equal, and the potential difference is substantially zero. Thereby, even if the external noise of any frequency enters from the substrate 11, it is possible to avoid the deterioration and error of the MR element 14 due to the influence of the external noise.

  Next, the configuration of the thin film magnetic head 1 relating to the output of the read signal in the reproducing unit 2 and the input of the write signal in the recording unit 3 will be described.

  The MR element 14 is connected to a pair of lead layers 41a and 41b for outputting signals read by the MR element 14 formed at intervals in the depth direction of the drawing. Similarly, a pair of lead layers 41c and 41d for inputting a write signal, which are formed at an interval in the depth direction of the drawing, are connected to the coil 20. From the lead layers 41a to 41d, extraction via plugs 42a to 42d extend in the stacking direction, respectively. The leading ends of the extraction via plugs 42 a to 42 d are connected to the electrode pads 43 a to 43 d on the surface of the overcoat layer 22, respectively.

  In FIG. 1, the extraction via plugs 42 a to 42 d and the electrode pads 43 a to 43 d are shown side by side in the horizontal direction in the figure, but these are actually formed side by side in the depth direction of the drawing. In FIG. 1, the lead layers 41a and 41b connected to the MR element 14 are shown as being connected to the second via plug 35b. However, the lead layers 41a and 41b and the second via plug 35b are in contact with each other. It is placed in a position that does not.

  The thin film magnetic head 1 described above is formed in a large number on a single wafer. A conceptual plan view of a wafer on which a large number of thin film magnetic heads 1 are formed is shown in FIG. The wafer 100 is obtained by forming the above-described various layers and elements on the disk-shaped member constituting the substrate 11 of the thin film magnetic head 1 shown in FIG. Partitioned. The head element assembly 101 includes a plurality of head elements 102 which are head structures at a stage before the medium facing surface S (see FIG. 1) is formed by polishing, and processing when the medium facing surface S is polished. Unit. That is, the head element assembly 101 is formed by forming a plurality of laminated structures on the substrate 11 including the reproducing unit 2 and the recording unit 3 of the thin film magnetic head 1 shown in FIG. is there. A cutting allowance (not shown) for cutting is provided between the head element assemblies 101 and between the head elements 102. The head element 102 is subjected to necessary processing such as polishing for forming the medium facing surface S to be the thin film magnetic head 1.

FIG. 3 is a schematic plan view of a configuration related to the recording unit 3 (see FIG. 1) of one head element 102 in the head element assembly 101 (see FIG. 2). In a state before the medium facing surface S is formed, the upper magnetic pole layer 19 and the lower magnetic pole / second upper shield layer 17 (see FIG. 1) are formed to extend to a position beyond the position that becomes the medium facing surface S. A measurement electrode pad 45 is disposed at a position beyond the medium facing surface S, and the upper magnetic pole layer 19 is electrically connected to the measurement electrode pad 45. The upper magnetic pole layer 19 and the measurement electrode pad 45 are formed of via plugs (not shown) in the same manner as the extraction via plugs 42c and 42d for connecting the lead layers 41c and 41d and the electrode pads 43c and 43d shown in FIG. Can be connected. Alternatively, the measurement electrode pad 45 itself may be formed as a via plug.
Further, as described above, the electrode pads 43 c and 43 d are electrically connected to the coil 20. As shown in FIG. 1, the upper magnetic pole layer 19 is electrically connected to the substrate 11 via the connection portion 21, the lower magnetic pole / second upper shield layer 17, the second via plug 35b, and the like. Since the polishing process for forming the medium facing surface S is performed from the lower side to the upper side of the head element 102 in FIG. 3, the measurement electrode pad 45 is removed by forming the medium facing surface S. The measurement electrode pad 45 is used only for measuring the insulation resistance, which will be described later, and becomes unnecessary after the measurement of the insulation resistance. Therefore, the configuration of the thin film magnetic head 1 (see FIG. 1) can be kept to a minimum by disposing the measurement electrode pad 45 in the region to be removed by polishing.

  In the present embodiment, in the manufacturing process of the thin film magnetic head 1 (see FIG. 1), the coil 20 and the top pole layer 19 are formed at the stage of the wafer 100 (see FIG. 2) or the head element assembly 101 (see FIG. 2). Measure the insulation resistance between. In other words, after measuring the insulation resistance, the medium facing surface S is formed and divided into individual thin film magnetic heads 1. As described above, the polishing process for forming the medium facing surface S is performed in units of the head element assembly 101 (see FIG. 2) in which a plurality of head elements 102 are arranged. In order to improve the measurement efficiency, The insulation resistance is measured simultaneously for a plurality of head elements 102.

  The insulation resistance is represented by an insulation resistance value between the top pole layer 19 and the coil 20, and the probe 50 connected to the electrode pad 43c (or 43d) and the measurement electrode pad 45 to a DC power source (not shown), respectively. Can be measured by applying a DC voltage between the upper magnetic pole layer 19 and the coil 20 via the probe 50. In the present embodiment, the application of a DC voltage between the upper magnetic pole layer 19 and the coil 20 is simultaneously performed on the plurality of head elements 102. At this time, the upper magnetic pole layer connected to the substrate 11 is used. A DC voltage is applied with the 19 side as plus (+) and the coil 20 side insulated from the substrate 11 as minus (−).

FIG. 4 conceptually shows a current flow generated when the insulation resistance is measured simultaneously for three head elements 102 as an example. In FIG. 4, since the substrate 11 is common to each head element 102, the potential V _{0 of the} substrate 11 is the same for each head element 102. In addition, since each set of probes 50 (see FIG. 3) is connected in parallel to a DC power supply, each upper magnetic pole layer is connected via the probe 50 when a voltage is simultaneously applied to each upper magnetic pole layer 19 by the probe 50. 19 is connected in parallel, and the potential V ₁ of the top pole layer 19 is substantially the same in each head element 102. Therefore, no current flows from the top pole layer 19 to the substrate 11 and only a current from the top pole layer 19 to the coil 20 flows.

  Here, as shown in FIG. 5, when a DC voltage is applied with the upper magnetic pole layer 19 side being minus (−) and the coil 20 side being plus (+), that is, when a voltage opposite to that in FIG. 4 is applied. think of.

In the case shown in FIG. 5, the potential V _{0 of the} substrate 11 is the same for each head element 102. On the other hand, when a voltage is simultaneously applied to the coil 20 by the probe 50 (see FIG. 3), the situation is the same as when the coils 20 are connected in parallel via the probe 50, and the potential of the coil 20 is substantially equal. The same applies to each head element 102. Therefore, when the insulation resistance between the top pole layer 19 and the coil 20 is different in each head element 102 due to manufacturing variations, defects, and the like, the potentials V _{1 to} V ₃ of the top pole layer 19 are different in each head element 102. . Since the upper magnetic pole layer 19 of each head element 102 is connected to the substrate 11, when a DC voltage is applied with the coil 20 side being positive, current flows from the coil 20 toward the upper magnetic pole layer 19, and further, Flow from layer 19 to substrate 11. At this time, if the potentials V _{1 to} V ₃ of the upper magnetic pole layer 19 of each head element 102 are different, the current flowing to the substrate 11 goes around to the other head element 102. Thus, even if the insulation resistance between the top pole layer 19 and the coil 20 is different for each head element 102 due to the sneak current generated from the substrate 11 to the top pole layer 19, the measured insulation resistance The values are almost the same for each head element 102, and an accurate measurement result cannot be obtained.

  On the other hand, as shown in FIG. 4, when a DC voltage is applied with the coil 20 side being negative and the upper magnetic pole layer 19 side being positive, another voltage is applied via the substrate 11 as shown in FIG. Since no sneak current is generated in the head element 102, each head element 102 has other than the impedance between the top pole layer 19 and the coil 20 even when the insulation resistance is measured for a plurality of head elements 102 at the same time. Not affected. As a result, the insulation resistance between the top pole layer 19 and the coil 20 of each head element 102 can be accurately measured.

  As a result, each magnetic layer (lower shield layer 13, first upper shield layer 15, etc.) is connected to the substrate 11 to prevent adverse effects due to charging of the magnetic layers and adverse effects due to parasitic capacitance generated in the insulating layers between the magnetic layers. Thus, the highly reliable thin film magnetic head 1 can be provided with stable quality by preventing outflow of defective insulation of the element. Here, the case where three head elements 102 are simultaneously measured has been described. However, the above-described phenomenon is the same regardless of whether the number of head elements 102 simultaneously measured is two or four or more. The number of 102 is not limited to three as long as it is plural.

  In a conventional thin film magnetic head in which the upper magnetic pole layer is not connected to the substrate, no sneak current is generated through the substrate. Therefore, either side of the upper magnetic pole layer or the coil is used as a plus for a plurality of head elements. Even when a DC voltage is applied simultaneously, the insulation resistance of each head element can be accurately measured. The above-described sneak current is a problem caused only by connecting the upper magnetic pole layer to the substrate.

  Next, a result of measuring the insulation resistance between the top pole layer 19 and the coil 20 for each head element 102 by actually manufacturing a wafer 100 on which a large number of head elements 102 are formed is shown. The number of head elements 102 formed on one wafer 100 is about 23,000, and 64 of them are a conventional configuration (conventional head) in which the upper magnetic pole layer 19 is not connected to the substrate 11. It formed in the position disperse | distributed substantially equally. The remaining head element 102 was formed with a configuration (new head) in which the top pole layer 19 and the substrate 11 were connected as shown in FIG. Both are the differences in whether or not the top pole layer 19 and the substrate 11 are connected. Except for this point, they have the same configuration and are manufactured under the same conditions.

Then, the following three types of measurements were performed on the wafer 100 manufactured as described above. In any measurement, a DC voltage was simultaneously applied to 12 head elements 102 at a time. Depending on the number of head elements 102, the last group for measuring the insulation resistance may be less than twelve (for example, in the conventional head, the last group is eight). In that case, the remaining head elements 102 that were less than 12 were measured together.
(Measurement 1) Measure the insulation resistance by applying a DC voltage to the new head with the coil side positive.
(Measurement 2) Measure the insulation resistance by applying a DC voltage to the new head with the upper magnetic pole side positive.
(Measurement 3) Measurement of insulation resistance by applying DC voltage to the conventional head.

  The histograms obtained by the measurements 1 to 3 are shown in FIGS.

  FIG. 8 is a measurement result for the conventional head, and it is considered that an accurate measurement result is obtained. 6 and 7 are compared on the basis of the distribution shown in FIG. 8, FIG. 6 shows a distribution similar to FIG. 8, whereas FIG. 7 shows a distribution different from FIG. In addition, there is extremely little variation in resistance value. When the median value was obtained as a reference, almost the same values were obtained in FIGS. From the above, in the thin film magnetic head in which the upper magnetic pole layer and the coil are connected, it can be said that an accurate measurement result can be obtained by applying a voltage with the upper magnetic pole layer side as a plus. 7 also shows that a sneak current is generated when a voltage is applied with the coil side being positive.

  In the present embodiment, the upper magnetic pole layer 19 is connected to the measurement electrode pad 45 as shown in FIG. 3, but the upper magnetic pole layer 19 is connected to the lower magnetic pole as shown in FIG. Since it is connected to the second upper shield layer 17, it is the same even if the lower magnetic pole and second upper shield layer 17 is connected to the measurement electrode pad 45 instead of the upper magnetic pole layer 19.

  Further, in the present embodiment, the measurement of the insulation resistance between the magnetic layer and the coil 20 in the recording unit 3 has been described, but the same applies to the measurement of the insulation resistance between the magnetic layer and the MR element 14 in the reproducing unit 2. It is.

  FIG. 9 shows a schematic plan view of a configuration relating to the reproducing unit 2 (see FIG. 1) of one head element 102 in the head element assembly 101 (see FIG. 2). As shown in FIG. 9, in a state before the medium facing surface S is formed, the lower shield layer 13 and the first upper shield layer 15 (hereinafter also referred to simply as a shield layer unless the upper portion and the lower portion are particularly distinguished) It is formed to extend to a position that exceeds the position that becomes the medium facing surface S, and is connected at a position that exceeds the medium facing surface S. Further, a measurement electrode pad 46 is disposed at a position beyond the medium facing surface S, and the shield layer is measured at a position beyond the medium facing surface S via a via plug (not shown) or directly. The electrode pad 46 is electrically connected. Further, as described above, the electrode pads 43 a and 43 b are electrically connected to the MR element 14, and the shield layer is electrically connected to the substrate 11. In FIG. 1, both the first shield layer 13 and the second shield layer 15 are connected to the substrate 11, but only one of them may be connected to the substrate 11.

  The insulation resistance between the shield layer and the MR element 14 is such that the probe 50 is pressed against the electrode pad 43 a (or 43 b) and the measurement electrode pad 46, and the shield layer and the MR element 14 are interposed via the probe 50. It can be measured by applying a DC voltage to.

  The measurement of the insulation resistance in the reproducing unit 2 is also performed at the stage of the wafer or the head element assembly in the thin film magnetic head manufacturing process. After measuring the insulation resistance, the medium facing surface S is formed, and each thin film magnetic head is measured. To divide. At the stage of the wafer or head element assembly, the shield layer of each head element 102 is electrically connected to the common substrate 11, so when applying a DC voltage to a plurality of head elements 102 simultaneously, Problems similar to those of the recording unit 3 (see FIG. 1) described above occur. Therefore, when measuring the insulation resistance of the reproducing unit 2, the shield layer side connected to the substrate 11 is plus (+), and the MR element 14 side insulated from the substrate 11 is minus (−). A DC voltage is simultaneously applied to the head element. As a result, the insulation resistance between the shield layer and the MR element 14 can be accurately measured for the reproducing unit 2 as well as the recording unit 3 without being affected by the sneak current. Further, when the insulation resistance of the reproducing unit 2 is measured, the number of head elements to be measured simultaneously is not particularly limited as long as the recording unit 3 is measured.

  The configuration shown in FIG. 9 can be combined with the configuration shown in FIG. In this case, two measurement electrode pads 45 and 46 are provided. However, a wiring layer (not shown) for routing is provided as necessary, and the positions of the measurement electrode pads 45 and 46 are overlapped with each other. Adjust appropriately so that it does not occur.

  Next, a head gimbal assembly and a hard disk device including the above-described thin film magnetic head will be described. First, the slider 210 included in the head gimbal assembly will be described with reference to FIG. In the hard disk device, the slider 210 is arranged to face a hard disk that is a disk-shaped recording medium that is driven to rotate. The slider 210 includes the thin-film magnetic head 1 obtained from the head element 102 (see FIG. 2), and the air bearing surface 200 is formed on the medium facing surface S facing the hard disk, and has a substantially hexahedral shape as a whole. Yes. When the hard disk rotates in the z direction in FIG. 10, lift is generated in the slider 210 downward in the y direction by the air flow passing between the hard disk and the slider 210. The slider 210 floats from the surface of the hard disk by this lifting force. The x direction in FIG. 10 is the track crossing direction of the hard disk. On the air outflow side end surface 211 of the slider 210, electrode pads for signal input and output to the reproducing unit 2 and the recording unit 3 (see FIG. 1) are formed. This surface corresponds to the upper end surface in FIG.

  Next, the head gimbal assembly 220 will be described with reference to FIG. The head gimbal assembly 220 includes a slider 210 and a suspension 221 that elastically supports the slider 210. The suspension 221 includes, for example, a leaf spring-shaped load beam 222 formed of stainless steel, a flexure 223 that is provided at one end of the load beam 222 and is joined to the slider 210 to give the slider 210 an appropriate degree of freedom, And a base plate 224 provided at the other end of the beam 222. The base plate 224 is attached to an arm 230 of an actuator for moving the slider 210 in the track crossing direction x of the hard disk 262. The actuator includes an arm 230 and a voice coil motor that drives the arm 230. In the flexure 223, a part to which the slider 210 is attached is provided with a gimbal part for keeping the posture of the slider 210 constant.

  The head gimbal assembly 220 is attached to the arm 230 of the actuator. A structure in which the head gimbal assembly 220 is attached to one arm 230 is called a head arm assembly. Further, a head gimbal assembly 220 attached to each arm of a carriage having a plurality of arms is called a head stack assembly.

  FIG. 11 shows an example of a head arm assembly. In this head arm assembly, a head gimbal assembly 220 is attached to one end of the arm 230. A coil 231 that is a part of the voice coil motor is attached to the other end of the arm 230. A bearing portion 233 attached to a shaft 234 for rotatably supporting the arm 230 is provided at an intermediate portion of the arm 230.

  Next, an example of the head stack assembly and the hard disk device according to the present embodiment will be described with reference to FIGS. FIG. 12 is an explanatory view showing the main part of the hard disk device, and FIG. 13 is a plan view of the hard disk device. The head stack assembly 250 has a carriage 251 having a plurality of arms 252. A plurality of head gimbal assemblies 220 are attached to the plurality of arms 252 so as to be arranged in the vertical direction at intervals. A coil 253 that is a part of the voice coil motor is attached to the carriage 251 on the opposite side of the arm 252. The head stack assembly 250 is incorporated in a hard disk device. The hard disk device has a plurality of hard disks 262 attached to a spindle motor 261. For each hard disk 262, two sliders 210 are arranged so as to face each other with the hard disk 262 interposed therebetween. Further, the voice coil motor has permanent magnets 263 arranged at positions facing each other with the coil 253 of the head stack assembly 250 interposed therebetween.

  The head stack assembly 250 and the actuator excluding the slider 210 support the slider 210 and position it relative to the hard disk 262.

  In the hard disk device, the slider 210 is moved with respect to the hard disk 262 by moving the slider 210 in the track crossing direction of the hard disk 262 by the actuator. The thin film magnetic head included in the slider 210 records information on the hard disk 262 by the recording unit, and reproduces information recorded on the hard disk 262 by the reproducing unit.

  In addition, this invention is not limited to the said embodiment, A various change is possible. For example, in the above-described embodiment, the thin film magnetic head having the structure in which the MR element for reading is formed on the substrate side and the inductive electromagnetic transducer for writing is stacked thereon has been described. It may be. In the above-described embodiment, the case where both the MR element and the induction type electromagnetic conversion element are included has been described as an example, but only one of them may be included.

1 is a conceptual cross-sectional view of a thin film magnetic head according to an embodiment of the present invention. It is a top view of the wafer in which the thin film magnetic head shown in FIG. 1 was formed. FIG. 3 is a schematic plan view of a configuration relating to a recording unit of the head element shown in FIG. 2. In the thin film magnetic head shown in FIG. 1, it is a figure which shows notionally the flow of an electric current at the time of applying a DC voltage by making the coil side into a minus between the magnetic layer of a recording part, and a coil. In the thin film magnetic head shown in FIG. 1, it is a figure which shows notionally the flow of an electric current at the time of applying a DC voltage by making a coil side into a plus between the magnetic layer and coil of a recording part. 5 is a histogram of insulation resistance measured as shown in FIG. It is the histogram of the insulation resistance measured as FIG. 6 is a histogram of insulation resistance measured with a thin film magnetic head in which the magnetic layer is not electrically connected to the substrate. FIG. 3 is a schematic plan view of a configuration relating to a reproducing unit of the head element shown in FIG. 2. It is a perspective view of a slider including a thin film magnetic head. FIG. 11 is a perspective view of a head gimbal assembly including the slider shown in FIG. 10. It is a principal part side view of the hard disk drive containing the head gimbal assembly shown in FIG. FIG. 12 is a plan view of a hard disk device including the head gimbal assembly shown in FIG. 11.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin-film magnetic head 2 Reproduction | regeneration part 3 Recording part 11 Substrate 12 Underlayer 12a Via hole 13 Lower shield layer 14 MR element 15 1st upper shield layer 16a, 16b, 38 Insulating layer 17 Lower magnetic pole and 2nd upper shield layer 18 Recording gap layer DESCRIPTION OF SYMBOLS 19 Upper magnetic pole layer 20 Coil 22 Overcoat layer 35a, 35b Via plug 37 Wiring 41a-41d Lead layer 42a-42d Lead-out via plug 43a-43d Electrode pad 45, 46 Measurement electrode pad 50 Probe 100 Wafer 101 Head element assembly 102 Head Element 210 Slider 220 Head gimbal assembly 250 Head stack assembly 262 Hard disk

Claims (6)

A method of measuring an insulation resistance of the inductive magnetic transducer in a manufacturing process of a thin film magnetic head having an inductive magnetic transducer,
A substrate and a plurality of inductive magnetic transducers formed on the substrate, each of the inductive magnetic transducers facing each other through a gap layer at one end and being magnetically coupled at the other end providing a pair of magnetic pole layer connected the substrate and electrically with the, and the magnetic pole layer and insulated with supported coil between said magnetic pole layers, the head element aggregate having a Process,
The magnetic pole layer side plus, the coil side as a minus, the by applying a DC voltage simultaneously to induction at least two of the magnetic conversion element, the insulation resistance between the magnetic pole layer and the coil have a, a step of measuring,
In the step of measuring the insulation resistance, each inductive magnetic transducer element is connected in parallel to a common positive potential, and in each inductive magnetic transducer element, the magnetic pole layer and the magnetic pole layer are set to the common positive potential side. A method for measuring insulation resistance, comprising forming a circuit connected in series with a coil . A method of measuring an insulation resistance of the magnetoresistive effect element in a manufacturing process of a thin film magnetic head having a head element including the magnetoresistive effect element,
A substrate, a plurality of magnetoresistive elements formed on the substrate, and first and second shield layers that are insulated from the magnetoresistive elements and sandwich each of the magnetoresistive elements, Providing a head element assembly in which at least one of the first and second shield layers is electrically connected to the substrate;
A DC voltage is simultaneously applied to at least two of the magnetoresistive effect elements, with the shield layer side electrically connected to the substrate being positive and the magnetoresistive effect element side being negative. the insulation resistance between the connected to shield layer and the magnetoresistive element have a, and measuring,
In the step of measuring the insulation resistance, the head elements are connected in parallel to a common positive potential, and in each head element, any one of the shield layers electrically connected to the substrate is connected to the common positive potential. A method for measuring insulation resistance, comprising forming a circuit in which the shield layer and the magnetoresistive effect element are connected in series on the potential side . A method of manufacturing a thin film magnetic head having an inductive magnetic transducer,
On a substrate, a pair of magnetic pole layer connected the substrate and electrically with the magnetically coupled with opposite other end with the gap layer at one end, the magnetic between said magnetic pole layer a step of fabricating the head element aggregates to form a plurality of inductive magnetic transducer comprising a coil which is supported by being insulated from the electrode layer, and
Measuring an insulation resistance of the inductive magnetic transducer of the head element assembly;
Dividing the head element assembly for which the insulation resistance has been measured for each inductive magnetic transducer, and
The step of measuring the insulation resistance includes:
The magnetic pole layer side plus, the coil side as a minus, the by applying a DC voltage simultaneously to induction at least two of the magnetic conversion element, the insulation resistance between the magnetic pole layer and the coil look including the step of measuring, the coil and the magnetic layer of the magnetic layer as the common positive potential side in the inductive magnetic transducer with the inductive magnetic transducer is connected in parallel to a common positive potential Forming a circuit connected in series with each other . Polishing the head element assembly for which the insulation resistance has been measured to further form a medium facing surface facing the recording medium;
The step of producing the head elements aggregate includes the steps of forming an electrode pad connected the the coil and electrically, the area to be removed by polishing in the step of forming the bearing surface, the magnetic pole layer and electrically Forming a measurement electrode pad to be electrically connected,
The method of manufacturing a thin film magnetic head according to claim 3, wherein the step of applying the DC voltage includes a step of pressing a probe connected to a DC power source to the electrode pad and the measurement electrode pad. A method of manufacturing a thin film magnetic head having a head element including a magnetoresistive element ,
A plurality of magnetoresistive elements, and first and second shield layers that are insulated from the magnetoresistive elements and sandwich each of the magnetoresistive elements, on the substrate; Producing a head element assembly in which at least one of the shield layers is electrically connected to the substrate;
Measuring the insulation resistance of the magnetoresistive element of the head element assembly;
Dividing the head element assembly measuring the insulation resistance for each magnetoresistive element,
The step of measuring the insulation resistance includes:
A DC voltage is simultaneously applied to at least two of the magnetoresistive effect elements, with the shield layer side electrically connected to the substrate being positive and the magnetoresistive effect element side being negative. to look including the step of measuring the insulation resistance between the connected shield layer and the magnetoresistive element, together with the head element is connected in parallel to a common positive potential, and the substrate in each head element A method of manufacturing a thin film magnetic head, comprising forming a circuit in which the shield layer and the magnetoresistive effect element are connected in series with any one of the shield layers electrically connected as the common positive potential side . Polishing the head element assembly for which the insulation resistance has been measured to further form a medium facing surface facing the recording medium;
The step of manufacturing the head element assembly includes the step of forming an electrode pad that is electrically connected to the magnetoresistive effect element, and the step of forming the medium facing surface in a region that is removed by polishing. Forming a measurement electrode pad that is electrically connected to the electrically connected shield layer, and
6. The method of manufacturing a thin film magnetic head according to claim 5, wherein the step of applying the DC voltage includes a step of pressing a probe connected to a DC power source to the electrode pad and the measurement electrode pad.

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