Thin-film magnetic head and method of manufacturing same

A thin-film magnetic head comprises a top pole layer incorporating a throat height defining layer, an intermediate layer, and a yoke portion layer. The yoke portion layer includes a track width defining portion for defining the track width. Each of the throat height defining layer, the intermediate layer, and the track width defining portion has a width equal to the track width. The length of the intermediate layer is greater than the length of the throat height defining layer, and the length of the yoke portion layer is greater than the length of the intermediate layer, each of the lengths being taken in the direction orthogonal to the air bearing surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin-film magnetic head having at least an induction-type electromagnetic transducer and a method of manufacturing such a thin-film magnetic head.

2. Description of the Related Art

Recent years have seen significant improvements in the areal recording density of hard disk drives. In particular, areal recording densities of latest hard disk drives have reached 100 to 160 gigabytes per platter and are even exceeding that level. It is required to improve the performance of thin-film magnetic heads, accordingly.

Among the thin-film magnetic heads, widely used are composite thin-film magnetic heads made of a layered structure including a recording (write) head having an induction-type electromagnetic transducer for writing and a reproducing (read) head having a magnetoresistive element (that may be hereinafter called an MR element) for reading.

In general, the write head incorporates: a medium facing surface (an air bearing surface) that faces toward a recording medium; a bottom pole layer and a top pole layer that are magnetically coupled to each other and include magnetic pole portions opposed to each other and located in regions of the pole layers on a side of the medium facing surface; a write gap layer provided between the magnetic pole portions of the top and bottom pole layers; and a thin-film coil at least part of which is disposed between the top and bottom pole layers and insulated from the top and bottom pole layers.

Higher track densities on a recording medium are essential to enhancing the recording density among the performances of the write head. To achieve this, it is required to implement the write head of a narrow track structure in which the track width, that is, the width of the two magnetic pole portions opposed to each other with the write gap layer disposed in between, the width being taken in the medium facing surface, is reduced down to microns or the order of submicron. Semiconductor process techniques are utilized to achieve the write head having such a structure. In addition, many write heads have a trim structure to prevent an increase in the effective track width due to expansion of a magnetic flux generated in the pole portions in the medium facing surface. The trim structure is a configuration in which the pole portion of the top pole layer, the write gap layer and a portion of the bottom pole layer have the same width taken in the medium facing surface. This structure is formed by etching the write gap layer and the portion of the bottom pole layer, using the pole portion of the top pole layer as a mask.

One of the performance characteristics required for the write head is an excellent overwrite property that is one of the characteristics required for overwrite. To improve the overwrite property, it is required that as many magnetic lines of flux passing through the two pole layers as possible be introduced to the pole portions so as to generate a magnetic field as large as possible near the write gap layer in the medium facing surface. Therefore, to improve the overwrite property, it is effective to employ a material having a high saturation flux density for the magnetic material of the pole portions, and to reduce the throat height. The throat height is the length (height) of the pole portions, that is, the portions of the two pole layers opposed to each other with the write gap layer in between, as taken from the medium-facing-surface-side end to the other end. The zero throat height level is the level of the end (opposite to the medium facing surface) of the portions of the two pole layers opposed to each other with the write gap layer in between. To improve the overwrite property, it is also effective to increase the distance between the two pole layers in a region farther from the medium facing surface than the zero throat height level.

However, a problem arises if many lines of flux are introduced to the pole portions to improve the overwrite property. The problem is that lines of flux leak from portions in the medium facing surface other than the neighborhood of the write gap layer, and the flux leakage causes side write and side erase. Side write is that data is written in a track adjacent to the intended track. Side erase is that data written in a track adjacent to the intended track is erased. To reduce the occurrences of side write and side erase, it is effective to increase the difference in levels of the bottom pole layer in the trim structure, that is, the difference between the level of a portion of an end face of the bottom pole layer exposed in the medium facing surface, the portion touching the write gap layer, and the level of portions on both sides.

The throat height may be determined by forming a stepped portion in the bottom or top pole layer. Methods of determining the throat height by forming a stepped portion in the bottom pole layer are disclosed in, for example, the U.S. Pat. No. 6,259,583B1, the U.S. Pat. No. 6,400,525B1, and the U.S. Pat. No. 5,793,578. Methods of determining the throat height by forming a stepped portion in the top pole layer are disclosed in, for example, the U.S. Pat. No. 6,043,959 and the U.S. Pat. No. 6,560,068B1.

The following problem arises if the throat height is determined by forming a stepped portion in the bottom pole layer. To improve the overwrite property, it is effective to reduce the throat height and to increase the difference in levels in the bottom pole layer that determines the throat height. To reduce the occurrences of side write and side erase, it is effective to increase the difference in levels of the bottom pole layer in the trim structure. To achieve this, however, the volume of the portion of the bottom pole layer located between the side portions forming the trim structure is extremely reduced. At the same time, the cross-sectional area of the magnetic path abruptly decreases in the neighborhood of the boundary between the above-mentioned portion of the bottom pole layer and the other portions. As a result, the flux saturates in the neighborhood of the boundary and the overwrite property is reduced. Furthermore, the end face of the bottom pole layer exposed in the medium facing surface has a width that abruptly changes at the bottom of the stepped portion of the trim structure. Consequently, the flux leaks from the neighborhood of the bottom of the stepped portion of the trim structure toward the recording medium, which causes side write and side erase.

In the case in which the throat height is determined by forming a stepped portion in the top pole layer, too, a problem is that the overwrite property is reduced if the cross-sectional area of the magnetic path of the top pole layer abruptly decreases in the neighborhood of the medium facing surface.

The following problem also arises if the throat height is determined by forming a stepped portion in the top pole layer. In prior art the stepped portion of the top pole layer that determines the throat height is formed as follows. A pole portion layer that determines the throat height is first formed on the write gap layer. Next, an insulating layer is formed to cover the pole portion layer and the write gap layer. The insulating layer is polished so that the top surface of the pole portion layer is exposed. According to this method, the thickness of the pole portion layer varies, depending on the depth removed by the above-mentioned polishing. It is therefore difficult to precisely control the writing characteristics of the head if this method is employed.

OBJECTS AND SUMMARY OF THE INVENTION

The invention is intended to solve the foregoing problems. It is a first object of the invention to provide a thin-film magnetic head to reduce the occurrences of side write and side erase and to improve the overwrite property of the thin-film magnetic head.

It is a second object of the invention to provide a method of manufacturing a thin-film magnetic head to reduce the occurrences of side write and side erase, to improve the overwrite property of the thin-film magnetic head, and to easily control the writing characteristics of the head with accuracy.

A thin-film magnetic head fabricated of the invention comprises: a medium facing surface that faces toward a recording medium; a first pole layer and a second pole layer that are magnetically coupled to each other and include magnetic pole portions opposed to each other and located in regions of the pole layers on a side of the medium facing surface; a gap layer provided between the pole portion of the first pole layer and the pole portion of the second pole layer; and a thin-film coil, at least part of the coil being disposed between the first and second pole layers and insulated from the first and second pole layers. The second pole layer incorporates: a throat height defining layer disposed adjacent to the gap layer and including an end portion for defining a throat height; a first track width defining layer disposed on a side of the throat height defining layer opposite to the gap layer and including a first track width defining portion for defining a track width; and a second track width defining layer disposed on a side of the first track width defining layer opposite to the throat height defining layer and including a second track width defining portion for defining the track width. Each of the throat height defining layer, the first track width defining portion and the second track width defining portion has a width taken in the medium facing surface that is equal to the track width. The length of the first track width defining layer is greater than the length of the throat height defining layer, and the length of the second track width defining layer is greater than the length of the first track width defining layer, each of the lengths being taken in the direction orthogonal to the medium facing surface.

According to the thin-film magnetic head of the invention, the throat height is defined by the throat height defining layer of the second pole layer. Each of the throat height defining layer, the first track width defining portion and the second track width defining portion has a width taken in the medium facing surface that is equal to the track width. According to the thin-film magnetic head of the invention, the length of the first track width defining layer taken in the direction orthogonal to the medium facing surface is greater than the length of the throat height defining layer, and the length of the second track width defining layer taken in the direction orthogonal to the medium facing surface is greater than the length of the first track width defining layer. As a result, the cross-sectional area of the magnetic path of the second pole layer gradually changes in the neighborhood of the medium facing surface.

According to the thin-film magnetic head of the invention, the first pole layer may include a portion adjacent to the gap layer, the portion having a width taken in the medium facing surface that is equal to the track width.

According to the thin-film magnetic head of the invention, the first track width defining layer may be a flat layer. The second track width defining layer may be a flat layer.

A method of the invention for manufacturing a thin-film magnetic head is a method of manufacturing the thin-film magnetic head of the invention. The method comprises the steps of: forming the first pole layer; forming the thin-film coil on the first pole layer; forming the gap layer on the pole portion of the first pole layer; forming a first magnetic layer for forming the throat height defining layer on the gap layer; forming a first mask on the first magnetic layer for forming the end portion for defining the throat height in the first magnetic layer; forming the end portion for defining the throat height in the first magnetic layer by selectively etching the first magnetic layer through the use of the first mask; forming a first nonmagnetic layer so as to fill an etched portion of the first magnetic layer while the first mask is left unremoved; and removing the first mask after the first nonmagnetic layer is formed.

The method of manufacturing the thin-film magnetic head of the invention further comprises the steps of forming a second magnetic layer for forming the first track width defining layer on the first magnetic layer and the first nonmagnetic layer after the first mask is removed; forming a second mask on the second magnetic layer for forming an end portion of the second magnetic layer opposite to the medium facing surface; forming the end portion of the second magnetic layer by selectively etching the second magnetic layer through the use of the second mask; forming a second nonmagnetic layer so as to fill an etched portion of the second magnetic layer while the second mask is left unremoved; and removing the second mask after the second nonmagnetic layer is formed.

The method of manufacturing the thin-film magnetic head of the invention further comprises the steps of: forming the second track width defining layer on the second magnetic layer and the second nonmagnetic layer after the second mask is removed; and etching the second magnetic layer and the first magnetic layer to align with the width of the second track width defining portion, so that the first magnetic layer is formed into the throat height defining layer and the second magnetic layer is formed into the first track width defining layer and that the width of each of the throat height defining layer, the first track width defining portion and the second track width defining portion that is taken in the medium facing surface is equal to the track width.

According to the method of manufacturing the thin-film magnetic head of the invention, the end portion for defining the throat height is formed in the first magnetic layer by selectively etching the first magnetic layer through the use of the first mask, and then the first nonmagnetic layer is formed to fill the etched portion of the first magnetic layer while the first mask is left unremoved. The first mask is then removed. Furthermore, according to the invention, the end portion of the second magnetic layer opposite to the medium facing surface is formed by selectively etching the second magnetic layer through the use of the second mask, and then the second nonmagnetic layer is formed to fill the etched portion of the second magnetic layer while the second mask is left unremoved. The second mask is then removed, and the second track width defining portion is formed on the second magnetic layer and the second nonmagnetic layer. It is thereby possible to easily control the thickness of each of the throat height defining layer and the first track width defining layer with accuracy.

According to the method of manufacturing the thin-film magnetic head of the invention, the step of etching the second magnetic layer and the first magnetic layer may further include etching of the gap layer and a portion of the first pole layer to align with the width of the second track width defining portion.

According to the method of the invention, the step of forming the end portion for defining the throat height may further include selective etching of the gap layer to a level as deep as the interface between the gap layer and the first pole layer.

According to the method of the invention, the step of forming the end portion for defining the throat height may further include selective etching of the gap layer to a depth somewhere in a middle of the thickness of the gap layer.

The method of the invention may further comprise the step of flattening top surfaces of the first magnetic layer and the first nonmagnetic layer by polishing, the step being provided between the step of removing the first mask and the step of forming the second magnetic layer. The depth to which the polishing is performed in the step of flattening may fall within a range of 10 to 50 nm inclusive.

The method of the invention may further comprise the step of flattening top surfaces of the second magnetic layer and the second nonmagnetic layer by polishing, the step being provided between the step of removing the second mask and the step of forming the second track width defining layer. The depth to which the polishing is performed in the step of flattening may fall within a range of 10 to 50 nm inclusive.

According to the method of the invention, the first track width defining layer may be a flat layer. The second track width defining layer may be a flat layer.

According to the method of the invention, the gap layer may be made of a nonmagnetic inorganic material, and the second magnetic layer and the first magnetic layer may be etched by reactive ion etching in the step of etching the second magnetic layer and the first magnetic layer. In this case, the nonmagnetic inorganic material may be one of the group consisting of alumina, silicon carbide and aluminum nitride.

According to the thin-film magnetic head or the method of manufacturing the same of the invention, the throat height is defined by the throat height defining layer of the second pole layer. Each of the throat height defining layer, the first track width defining portion and the second track width defining portion has a width taken in the medium facing surface that is equal to the track width. According to the thin-film magnetic head of the invention, the length of the first track width defining layer taken in the direction orthogonal to the medium facing surface is greater than the length of the throat height defining layer, and the length of the second track width defining layer taken in the direction orthogonal to the medium facing surface is greater than the length of the first track width defining layer. As a result, the cross-sectional area of the magnetic path of the second pole layer gradually changes in the neighborhood of the medium facing surface. Therefore, according to the invention, the overwrite property of the thin-film magnetic head is improved while the occurrences of side write and side erase are suppressed.

Furthermore, according to the method of manufacturing the thin-film magnetic head of the invention, it is possible to easily control the thickness of the throat height defining layer and the first track width defining layer with accuracy. As a result, according to the method of manufacturing the thin-film magnetic head of the invention, the writing characteristics of the thin-film magnetic head are easily controlled with accuracy.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention will now be described in detail with reference to the accompanying drawings.

First Embodiment

Reference is now made toFIG. 1AtoFIG. 17A,FIG. 1BtoFIG. 17B,FIG. 18andFIG. 19to describe a method of manufacturing a thin-film magnetic head of a first embodiment of the invention.FIG. 1AtoFIG. 17Aare cross sections orthogonal to the air bearing surface and the top surface of a substrate.FIG. 1BtoFIG. 17Bare cross sections of magnetic pole portions each of which is parallel to the air bearing surface.FIG. 18is a plan view showing the configuration and arrangement of a thin-film coil of the thin-film magnetic head of the embodiment.FIG. 19is a perspective view for illustrating the configuration of the thin-film magnetic head in which an overcoat layer is omitted.

In the method of manufacturing the thin-film magnetic head of the embodiment, a step shown inFIG. 1AandFIG. 1Bis first performed. In the step an insulating layer2made of alumina (Al2O3), for example, is deposited to a thickness of approximately 1 to 3 μm on a substrate1made of aluminum oxide and titanium carbide (Al2O3—TiC), for example. Next, a bottom shield layer3for a read head, made of a magnetic material such as Permalloy and having a thickness of approximately 2 to 3 μm, is formed on the insulating layer2. The bottom shield layer3is selectively formed on the insulating layer2by plating through the use of a photoresist film as a mask, for example. Although not shown, an insulating layer that is made of alumina, for example, and has a thickness of 3 to 4 μm, for example, is formed over the entire surface. The insulating layer is then polished by chemical mechanical polishing (hereinafter referred to as CMP), for example, to expose the bottom shield layer3and to flatten the surface.

On the bottom shield layer3, a bottom shield gap film4serving as an insulating film and having a thickness of approximately 20 to 40 nm, for example, is formed. On the bottom shield gap film4, an MR element5for magnetic signal detection having a thickness of tens of nanometers is formed. For example, the MR element5may be formed by selectively etching an MR film formed by sputtering. The MR element5is located near a region in which the air bearing surface described later is to be formed. The MR element5may be an element made up of a magnetosensitive film that exhibits magnetoresistivity, such as an AMR element, a GMR element or a TMR (tunnel magnetoresistive) element. Next, although not shown, a pair of electrode layers, each having a thickness of tens of nanometers, to be electrically connected to the MR element5are formed on the bottom shield gap film4. A top shield gap film7serving as an insulating film and having a thickness of approximately 20 to 40 nm, for example, is formed on the bottom shield gap film4and the MR element5. The MR element5is embedded in the shield gap films4and7. Examples of insulating materials used for the shield gap films4and7include alumina, aluminum nitride, and diamond-like carbon (DLC). The shield gap films4and7may be formed by sputtering or chemical vapor deposition (hereinafter referred to as CVD).

Next, a top shield layer8for a read head, made of a magnetic material and having a thickness of approximately 1.0 to 1.5 μm, is selectively formed on the top shield gap film7. Next, although not shown, an insulating layer made of alumina, for example, and having a thickness of 2 to 3 μm, for example, is formed over the entire surface, and polished by CMP, for example, so that the top shield layer8is exposed, and the surface is flattened.

An insulating layer9made of alumina, for example, and having a thickness of approximately 0.3 μm, for example, is formed over the entire top surface of the layered structure obtained through the foregoing steps. On the entire top surface of the insulating layer9, a first layer10aof the bottom pole layer10made of a magnetic material and having a thickness of approximately 0.5 to 1.0 μm is formed. The first layer10ahas a top surface that is flat throughout. The bottom pole layer10includes the first layer10a, and a second layer10b, a third layer10d, a fourth layer10f, and coupling layers10c,10eand10gthat will be described later.

The first layer10amay be formed by plating, using NiFe (80 weight % Ni and 20 weight % Fe), or a high saturation flux density material such as NiFe (45 weight % Ni and 55 weight % Fe), CoNiFe (10 weight % Co, 20 weight % Ni and 70 weight % Fe), or FeCo (67 weight % Fe and 33 weight % Co). Alternatively, the first layer10amay be formed by sputtering, using a high saturation flux density material such as CoFeN, FeAlN, FeN, FeCo, or FeZrN. In this embodiment the first layer10ais formed by sputtering to have a thickness of 0.5 to 1.0 μm by way of example.

Next, an insulating film11made of alumina, for example, and having a thickness of 0.2 μm, for example, is formed on the first layer10a. The insulating film11is then selectively etched to form openings in the insulating film11in regions in which the second layer10band the coupling layer10care to be formed.

Next, although not shown, an electrode film of a conductive material having a thickness of 50 to 80 nm is formed by sputtering, for example, so as to cover the first layer10aand the insulating film11. This electrode film functions as an electrode and a seed layer for plating. Next, although not shown, a frame is formed on the electrode film by photolithography. The frame will be used for forming a first coil13by plating.

Next, electroplating is performed, using the electrode film, to form the first coil13made of a metal such as copper (Cu) and having a thickness of approximately 3.0 to 3.5 μm. The first coil13is disposed in the region in which the insulating film11is located. Next, the frame is removed, and portions of the electrode film except the portion below the first coil13are removed by ion beam etching, for example.

Next, although not shown, a frame is formed on the first layer10aand the insulating film11by photolithography. The frame will be used for forming the second layer10band the coupling layer10cof the bottom pole layer10by frame plating.

FIG. 2AandFIG. 2Billustrate the following step. In the step electroplating is performed to form the second layer10band the coupling layer10c, each of which is made of a magnetic material and has a thickness of 3.5 to 4.0 μm, for example, on the first layer10a. For example, the second layer10band the coupling layer10cmay be made of NiFe, CoNiFe or FeCo. In the present embodiment the second layer10band the coupling layer10care made of CoNiFe having a saturation flux density of 1.9 to 2.3 tesla (T) by way of example. In the embodiment, when the second layer10band the coupling layer10care formed by plating, no specific electrode film is provided, but the unpatterned first layer10ais used as an electrode and a seed layer for plating.

Next, although not shown, a photoresist layer is formed to cover the first coil13, the second layer10band the coupling layer10c. Using the photoresist layer as a mask, the first layer10ais selectively etched by reactive ion etching or ion beam etching, for example. The first layer10ais thus patterned. Next, the photoresist layer is removed.

FIG. 3AandFIG. 3Billustrate the following step. In the step an insulating layer15made of photoresist, for example, is formed in a region in which a second coil19described later is to be located. The insulating layer15is formed so that at least the space between the second layer10band the first coil13, the space between the turns of the first coil13, and the space between the coupling layer10cand the first coil13are filled with the insulating layer15. Next, an insulating layer16made of alumina, for example, and having a thickness of 4 to 6 μm is formed so as to cover the insulating layer15.

FIG. 4AandFIG. 4Billustrate the following step. In the step the insulating layers15and16are polished by CMP, for example, so that the second layer10b, the coupling layer10cand the insulating layer15are exposed, and the top surfaces of the second layer10b, the coupling layer10cand the insulating layers15and16(which is not shown inFIG. 4AandFIG. 4B) are flattened.

FIG. 5AandFIG. 5Billustrate the following step. In the step the insulating layer15is removed, and an insulating film17made of alumina, for example, is then formed by CVD, for example, so as to cover the entire top surface of the layered structure. As a result, grooves covered with the insulating film17are formed in the space between the second layer10band the first coil13, the space between the turns of the first coil13, and the space between the coupling layer10cand the first coil13. The insulating film17has a thickness of 0.08 to 0.15 μm, for example. The insulating film17may be formed by CVD, for example, wherein a gas of H2O, N2O, H2O2or O3(ozone) as a material used for making thin films and Al(CH3)3or AlCl3as a material used for making thin films are alternately ejected in an intermittent manner under a reduced pressure at a temperature of 180 to 220° C. Through this method, a plurality of thin alumina films are stacked so that the insulating film17that is closely-packed and exhibits a good step coverage, and has a desired thickness is formed.

Next, a first conductive film made of Cu, for example, and having a thickness of 50 nm, for example, is formed by sputtering so as to cover the entire top surface of the layered structure. On the first conductive film, a second conductive film made of Cu, for example, and having a thickness of 50 nm, for example, is formed by CVD. The second conductive film is not intended to be used for entirely filling the groove between the second layer10band the first coil13, the groove between the turns of the first coil13, and the groove between the coupling layer10cand the first coil13, but is intended to cover the grooves, taking advantage of good step coverage of CVD. The first and second conductive films in combination are called an electrode film. The electrode film functions as an electrode and a seed layer for plating. Next, on the electrode film, a conductive layer19pmade of a metal such as Cu and having a thickness of 3 to 4 μm, for example, is formed by plating. The electrode film and the conductive layer19pare used for making the second coil19. The conductive layer19pof Cu is formed through plating on the second conductive film of Cu formed by CVD, so that the second coil19is properly formed in the space between the second layer10band the first coil13, the space between the turns of the first coil13, and the space between the coupling layer10cand the first coil13.

FIG. 6AandFIG. 6Billustrate the following step. In the step the conductive layer19pis polished by CMP, for example, so that the second layer10b, the coupling layer10c, and the first coil13are exposed. As a result, the second coil19is made up of the conductive layer19pand the electrode film that remain in the space between the second layer10band the first coil13, the space between the turns of the first coil13, and the space between the coupling layer10cand the first coil13. The above-mentioned polishing is performed such that each of the second layer10b, the coupling layer10c, the first coil13and the second coil19has a thickness of 2.0 to 3.0 μm, for example. The second coil19has turns at least part of which is disposed between turns of the first coil13. The second coil19is formed such that only the insulating film17is provided between the turns of the first coil13and the turns of the second coil19.

FIG. 18illustrates the first coil13and the second coil19.FIG. 6Ais a cross section taken along line6A—6A ofFIG. 18. Connecting layers21,46and47, the top pole layer30and the air bearing surface42that will be formed later are shown inFIG. 18, too. As shown inFIG. 18, a connecting portion13ais provided near an inner end of the first coil13. A connecting portion13bis provided near an outer end of the first coil13. A connecting portion19ais provided near an inner end of the second coil19. A connecting portion19bis provided near an outer end of the second coil19.

In the step of forming the first coil13or the step of forming the second coil19, two lead layers44and45are formed to be disposed outside the first layer10aof the bottom pole layer10, as shown inFIG. 18. The lead layers44and45have connecting portions44aand45a, respectively.

The connecting portions13aand19bare connected to each other through a connecting layer21that will be formed later. The connecting portions44aand13bare connected to each other through a connecting layer46that will be formed later. The connecting portions19aand45aare connected to each other through a connecting layer47that will be formed later.

FIG. 7AandFIG. 7Billustrate the following step. In the step an insulating film20made of alumina, for example, and having a thickness of 0.1 to 0.3 μm is formed to cover the entire top surface of the layered structure. Etching is selectively performed on the insulating film20in the portions corresponding to the second layer10b, the coupling layer10c, the two connecting portions13aand13bof the first coil13, the two connecting portions19aand19bof the second coil19, the connecting portion44aof the lead layer44, and the connecting portion45aof the lead layer45. The insulating film20thus etched covers the top surfaces of the coils13and19except the two connecting portions13aand13bof the first coil13and the two connecting portions19aand19bof the second coil19.

Next, the connecting layers21,46and47ofFIG. 18are formed by frame plating, for example. The connecting layers21,46and47are made of a metal such as Cu and each have a thickness of 0.8 to 1.5 μm, for example.

Next, a third layer10dis formed on the second layer10b, and a coupling layer10eis formed on the coupling layer10ceach by frame plating, for example. The third layer10dand the coupling layer10emay be made of NiFe, CoNiFe or FeCo, for example. In the embodiment the third layer10dand the coupling layer10eare made of CoNiFe having a saturation flux density of 1.9 to 2.3 T by way of example. The third layer10dand the coupling layer10eeach have a thickness of 0.8 to 1.5 μm, for example.

Next, an insulating film22made of alumina, for example, and having a thickness of 1 to 2 μm is formed to cover the entire top surface of the layered structure. The insulating film22is then polished by CMP, for example. This polishing is performed such that the top surfaces of the third layer10d, the coupling layer10e, the connecting layers21,46and47, and the insulating film22are flattened and each of these layers has a thickness of 0.3 to 1.0 μm.

Next, although not shown, a magnetic layer made of a magnetic material and having a thickness of 0.3 to 0.5 μm is formed by sputtering, so as to cover the entire top surface of the layered structure. The magnetic layer may be made of a high saturation flux density material such as CoFeN, FeAlN, FeN, FeCo, or FeZrN. In the embodiment the magnetic layer is made of CoFeN having a saturation flux density of 2.4 T by way of example.

FIG. 8AandFIG. 8Billustrate the following step. In the step, on the magnetic layer, an etching mask24ais formed in the portion corresponding to the third layer10d, and an etching mask24bis formed in the portion corresponding to the coupling layer10e. Each of the etching masks24aand24bhas an undercut so that the bottom surface is smaller than the top surface in order to facilitate lift-off that will be performed later. Such etching masks24aand24bmay be formed by patterning a resist layer made up of two stacked organic films, for example.

Next, the magnetic layer is selectively etched by ion beam etching, for example, through the use of the etching masks24aand24b. The fourth layer10fand the coupling layer10gare thereby formed on the third layer10dand the coupling layer10e, respectively. The fourth layer10fand the coupling layer10gare made up of portions of the magnetic layer remaining under the etching masks24aand24bafter the etching. This etching is performed such that the direction in which ion beams move forms an angle in a range of 0 to 20 degrees inclusive with respect to the direction orthogonal to the top surface of the first layer10a. Next, to remove deposits on the sidewalls of the magnetic layer23after the etching, another etching is performed such that the direction in which ion beams move forms an angle in a range of 60 to 75 degrees inclusive with respect to the direction orthogonal to the top surface of the first layer10a.

Next, an insulating layer25made of alumina, for example, and having a thickness of 0.4 to 0.6 μm is formed so as to cover the entire top surface of the layered structure while the etching masks24aand24bare left unremoved. The insulating layer25is formed in a self-aligned manner so as to fill the etched portion of the above-mentioned magnetic layer. The etching masks24aand24bare then lifted off. Next, CMP is performed for a short period of time, for example, to polish and flatten the top surfaces of the fourth layer10f, the coupling layer10gand the insulating layer25. This flattening removes small differences in levels between the fourth layer10fand the insulating layer25, and between the coupling layer10gand the insulating layer25, and removes remainders and burrs of the etching masks24aand24bafter lift-off is performed.

FIG. 9AandFIG. 9Billustrate the following step. In the step a write gap layer26having a thickness of 0.07 to 0.1 μm is formed to cover the entire top surface of the layered structure. The write gap layer26may be made of an insulating material such as alumina or a nonmagnetic metal material such as Ru, NiCu, Ta, W or NiB. Next, a portion of the write gap layer26corresponding to the coupling layer10gis selectively etched.

Next, a first magnetic layer27made of a magnetic material and having a thickness of 0.1 to 0.3 μm is formed by sputtering, for example, so as to cover the entire top surface of the layered structure. The magnetic layer27may be made of a high saturation flux density material such as CoFeN, FeAlN, FeN, FeCo or FeZrN. The magnetic layer27preferably has a higher flux density. In the embodiment the magnetic layer27is made of CoFeN having a saturation flux density of 2.4 T by way of example.

Next, etching masks28aand28bare formed on the magnetic layer27. The etching mask28ais provided for forming an end portion for defining the throat height in the magnetic layer27, and the mask28ais disposed above the fourth layer10f. The etching mask28bis disposed above the coupling layer10g. Each of the etching masks28aand28bhas an undercut so that the bottom surface is smaller than the top surface in order to facilitate lift-off that will be performed later. Such etching masks28aand28bmay be formed by patterning a resist layer made up of two stacked organic films, for example.

FIG. 10AandFIG. 10Billustrate the following step. In the step the magnetic layer27is selectively etched by ion beam etching, for example, through the use of the etching masks28aand28b. A magnetic layer30apand a coupling layer30bare thereby made up of portions of the magnetic layer27remaining under the etching masks28aand28bafter the etching.

The magnetic layer30apis disposed adjacent to the write gap layer26. The magnetic layer30apis patterned later to be a throat height defining layer30a. At this point the magnetic layer30aphas a width greater than the write track width. The magnetic layer30aphas an end portion30a1for defining the throat height. The coupling layer30bis disposed on top of the coupling layer10g. The above-mentioned etching may be performed such that the direction in which ion beams move forms an angle in a range of 0 to 20 degrees inclusive with respect to the direction orthogonal to the top surface of the first layer10a. Next, to remove deposits on the sidewalls of the magnetic layer27after the etching, another etching is performed such that the direction in which ion beams move forms an angle in a range of 60 to 75 degrees inclusive with respect to the direction orthogonal to the top surface of the first layer10a. The magnetic layer27is etched in such a manner so that the end portion30a1for defining the throat height is formed to be nearly orthogonal to the top surface of the first layer10a. The throat height is thereby defined with accuracy.

The magnetic layer27may be etched in the following manner. A mask is formed on the magnetic layer27by frame plating, for example. Next, the magnetic layer27is etched by reactive ion etching, for example, using the mask. A halogen gas such as Cl2or a mixture of BCl3and Cl2is utilized for the etching. The magnetic layer27is preferably etched at a temperature of 50° C. or higher so that the etching rate is increased. More preferably, the temperature falls within the range of 200 to 300° C. inclusive so that the etching is more successfully performed. It is preferred to use a gas containing a halogen gas and O2or CO2for etching the magnetic layer27. The halogen gas may be a gas containing at least one of Cl2and BCl3. Through the use of the mixture of O2and a halogen gas containing Cl2, the profile of the magnetic layer27that has been etched is controlled with accuracy. If the mixture of O2and a halogen gas containing Cl2and BCl3is used, in particular, deposits of molecules of the halogen gas on the surface of the layered structure will be removed so that the surface of the layered structure is made very clean.

The rate of etching the magnetic layer27is higher if a gas containing Cl2and CO2, a gas containing Cl2, BCl3and CO2, or a gas containing BCl3, Cl2, O2and CO2is used, compared to the case in which a gas that does not contain CO2is used. As a result, the etching selectivity of the magnetic layer27to the etching mask is increased by 30 to 50%.

After the magnetic layer27is etched, the write gap layer26is selectively etched by ion beam etching, for example, to the level of the interface between the write gap layer26and the fourth layer10fof the bottom pole layer10, using the etching masks28aand28b.

Next, a first nonmagnetic layer31made of a nonmagnetic material is formed by lift-off. That is, the nonmagnetic layer31having a thickness of 0.2 to 0.4 μm is formed to cover the entire top surface of the layered structure while the etching masks28aand28bare left unremoved. The nonmagnetic layer31is formed in a self-aligned manner such that the etched portions of the magnetic layer27and the write gap layer26are filled with the nonmagnetic layer31. The nonmagnetic layer31is preferably formed such that the top surface thereof is located in nearly the same level as the top surface of the magnetic layer30ap. The nonmagnetic layer31may be made of an insulating material such as alumina.

FIG. 11AandFIG. 11Billustrate the following step. In the step the etching masks28aand28bare lifted off, and the top surfaces of the magnetic layer30ap, the coupling layer30band the nonmagnetic layer31are then polished and flattened by CMP, for example. InFIG. 11AandFIG. 11Bnumeral32indicates the level in which polishing is stopped. The depth to which the polishing is performed falls within a range of 10 to 50 nm inclusive, for example.

FIG. 12AandFIG. 12Billustrate the following step. In the step a second magnetic layer33made of a magnetic material and having a thickness of 0.1 to 0.3 μm is formed by sputtering, for example, to cover the entire top surface of the layered structure. The magnetic layer33is made of a high saturation flux density material such as CoFeN, FeAlN, FeN, FeCo or FeZrN. The magnetic layer33is preferably has a high saturation flux density. In the embodiment the magnetic layer33is made of CoFeN having a saturation flux density of 2.4 T.

Next, etching masks34aand34bare formed on the magnetic layer33. The etching mask34ais a mask for forming an end portion of the magnetic layer33opposite to the air bearing surface. The mask34ais disposed above the magnetic layer30ap. The etching mask34bis disposed above the coupling layer30b. Each of the etching masks34aand34bhas an undercut so that the bottom surface is smaller than the top surface in order to facilitate lift-off that will be performed later. Such etching masks34aand34bmay be formed by patterning a resist layer made up of two stacked organic films, for example.

FIG. 13AandFIG. 13Billustrate the following step. In the step the magnetic layer33is selectively etched by ion beam etching, for example, through the use of the etching masks34aand34b. A magnetic layer30cpand a coupling layer30dare made up of portions of the magnetic layer33remaining under the etching masks34aand34bafter the etching. The coupling layers30band30dtogether with the coupling layers10c,10eand10gmake up the coupling section43.

The magnetic layer30cpis disposed on a side of the magnetic layer30apfarther from the write gap layer26. The magnetic layer30cpwill be patterned to be an intermediate layer30c. At this time the magnetic layer30cphas a width greater than the write track width. The magnetic layer30cphas an end portion30c1located opposite to the air bearing surface. The coupling layer30dis disposed on the coupling layer30b. The magnetic layer33may be etched through a method similar to the method of etching the magnetic layer27, for example.

Next, a second nonmagnetic layer35made of a nonmagnetic material is formed by lift-off. That is, the nonmagnetic layer35having a thickness of 0.2 to 0.4 μm is formed to cover the entire top surface of the layered structure while the etching masks34aand34bare left unremoved. The nonmagnetic layer35is formed in a self-aligned manner such that the etched portions of the magnetic layer33are filled with the nonmagnetic layer35. The nonmagnetic layer35is preferably formed such that the top surface thereof is located in nearly the same level as the top surface of the magnetic layer30cp. The nonmagnetic layer35may be made of an insulating material such as alumina.

FIG. 14AandFIG. 14Billustrate the following step. In the step the etching masks34aand34bare lifted off, and the top surfaces of the magnetic layer30cp, the coupling layer30dand the nonmagnetic layer35are then polished and flattened by CMP, for example. InFIG. 14AandFIG. 14Bnumeral36indicates the level in which polishing is stopped. The depth to which the polishing is performed falls within a range of 10 to 50 nm inclusive, for example.

FIG. 15AandFIG. 15Billustrate the following step. In the step a magnetic layer37made of a magnetic material and having a thickness of 0.1 to 0.3 μm is formed by sputtering, for example, to cover the entire top surface of the layered structure. The magnetic layer37is made of a high saturation flux density material such as CoFeN, FeAlN, FeN, FeCo or FeZrN.

Next, a yoke portion layer30fmade of a magnetic material is formed by frame plating, for example, on the magnetic layer37, wherein the magnetic layer37is used as an electrode and a seed layer. The yoke portion layer30fhas a thickness of 3 to 4 μm, for example. The yoke portion layer30fmay be made of CoNiFe or FeCo having a saturation flux density of 2.3 T, for example. The yoke portion layer30fis disposed to extend from a region corresponding to the magnetic layer30cpto a region corresponding to the coupling layer30d.

FIG. 16AandFIG. 16Billustrate the following step. In the step the magnetic layers37,30cpand30apand the write gap layer26are selectively etched by ion beam etching, for example, using the yoke portion layer30fas an etching mask. The magnetic layer37thus etched is a yoke portion layer30e. The plane geometry of the yoke portion layer30eis the same as that of the yoke portion layer30f. The magnetic layer30cpthus etched is the intermediate layer30c. The magnetic layer30apthus etched is a throat height defining layer30a. After the above-mentioned etching is performed, the yoke portion layer30fhas a thickness of 1 to 2 μm, for example. The top pole layer30is made up of the throat height defining layer30a, the intermediate layer30c, the coupling layers30band30d, and the yoke portion layers30eand30f.

As shown inFIG. 19, the layered structure made up of the yoke portion layers30eand30fincludes a second track width defining portion30A and a yoke portion30B. The second track width defining portion30A has an end located in the air bearing surface42and the other end located away from the air bearing surface. The yoke portion30B is coupled to the other end of the track width defining portion30A. The track width defining portion30A has a uniform width. The track width defining portion30A initially has a width of about 0.15 to 0.2 μm, for example. The yoke portion30B is equal in width to the track width defining portion30A at the interface with the track width defining portion30A. The yoke portion30B gradually increases in width as the distance from the track width defining portion30A increases, and then maintains a specific width to the end.

Next, although not shown, a photoresist mask having an opening around the track width defining portion30A is formed. Using the photoresist mask and the track width defining portion30A as masks, a portion of the fourth layer10fis etched by ion beam etching, for example. This etching may be performed such that the direction in which ion beams move forms an angle in a range of 35 to 55 degrees inclusive, for example, with respect to the direction orthogonal to the top surface of the first layer10a. The depth to which the fourth layer10fis etched is preferably 0.1 to 0.4 μm, and more preferably 0.1 to 0.3 μm. If the depth to which the etching is performed is 0.5 μm or greater, the occurrences of side write or side erase increase.

A trim structure is thereby formed, wherein a portion of the fourth layer10f, the write gap layer26, the throat height defining layer30a, the intermediate layer30c, and the track width defining portion30A have the same widths in the air bearing surface. The trim structure suppresses an increase in the effective write track width due to expansion of a magnetic flux generated during writing in a narrow track.

Next, sidewalls of the portion of the fourth layer10f, the write gap layer26, the throat height defining layer30a, the intermediate layer30cand the track width defining portion30A are etched by ion beam etching, for example, to reduce the widths of these layers in the air bearing surface down to 0.1 μm, for example. This etching may be performed such that the direction in which ion beams move forms an angle in a range of 40 to 75 degrees inclusive, for example, with respect to the direction orthogonal to the top surface of the first layer10a.

FIG. 17AandFIG. 17Billustrate the following step. In the step the overcoat layer38made of alumina, for example, and having a thickness of 20 to 30 μm is formed so as to cover the entire top surface of the layered structure. The surface of the overcoat layer38is flattened, and electrode pads (not shown) are formed thereon. Finally, the slider including the foregoing layers is lapped to form the air bearing surface42. The thin-film magnetic head including the read and write heads is thus completed.

According to the embodiment, the following method may be employed to form the yoke portion layers as shown inFIG. 20AandFIG. 20B, instead of forming the yoke portion layers30eand30fby frame plating as described with reference toFIG. 15AandFIG. 15B.FIG. 20Ais a cross section orthogonal to the air bearing surface and the top surface of the substrate.

FIG. 20Bis a cross section of the pole portions parallel to the air bearing surface. In this method a magnetic layer made of a magnetic material and having a thickness of 1.0 to 1.5 μm is formed by sputtering on the entire top surface of the layered structure including the flattened top surfaces of the magnetic layer30cp, the coupling layer30dand the nonmagnetic layer35. The magnetic layer may be made of CoFeN or FeCo having a saturation flux density of 2.4 T. Next, an insulating layer made of alumina, for example, and having a thickness of 0.3 to 2.0 μm is formed on the magnetic layer. Next, an etching mask having a thickness of 0.5 to 1.0 μm, for example, is formed by frame plating, for example, on the insulating layer. The etching mask may be made of NiFe (45 weight % Ni and 55 weight % Fe), CoNiFe (67 weight % Co, 15 weight % Ni and 18 weight % Fe) having a saturation flux density of 1.9 to 2.1 T, or FeCo (60 weight % Fe and 40 weight % Co) having a saturation flux density of 2.3 T. The plane geometry of the etching mask is the same as that of the yoke portion layer30f. The etching mask has a portion for defining the track width. This portion has a width of 0.1 to 0.2 μm, for example.

Next, the insulating layer is selectively etched by reactive ion etching, for example, using the etching mask. A halogen gas such as Cl2or a mixture of BCl3and Cl2is utilized for this etching. The etching mask may be either removed or left unremoved through the etching. If the etching mask is removed, it is possible to perform etching of the magnetic layer later with more accuracy. Next, the magnetic layer is selectively etched by reactive ion etching, for example, using the insulating layer as another etching mask39. The magnetic layer is preferably etched at a temperature of 50° C. or higher so that the etching rate is increased. More preferably, the temperature falls within the range of 200 to 300° C. inclusive so that the etching is more successfully performed. The magnetic layer that has been etched serves as a yoke portion layer30g. In this example the top pole layer30is made up of the throat height defining layer30a, the intermediate layer30c, the coupling layers30band30d, and the yoke portion layer30g.

Alternatively, as shown inFIG. 20AandFIG. 20B, it is possible that the etching mask39is formed on the magnetic layer that is to be the yoke portion layer30gas described above, and the magnetic layer30ap(SeeFIG. 15AandFIG. 15B), the magnetic layer30cp, and the magnetic layer to be the yoke portion layer30gare selectively etched by reactive ion etching, using the etching mask39to form the yoke portion layer30g, the intermediate layer30c, and the throat height defining layer30a. In this case, the write gap layer26is preferably made of a nonmagnetic inorganic material such as alumina, silicon carbide (SiC), or aluminum nitride (AWN). It is thereby possible that the etching rate of the write gap layer26is lower than that of the magnetic layer when the magnetic layer made of a magnetic material including at least iron that is one of the group consisting of iron and cobalt, such as CoFeN or FeCo, is etched by reactive ion etching. As a result, the sidewalls of the magnetic layer that has been etched form an angle of nearly 90 degrees with respect to the top surface of the write gap layer26. It is thereby possible to define the track width with accuracy.

This feature will now be described in detail. For example, a case is considered wherein the magnetic layer including at least iron that is one of the group consisting of iron and cobalt is etched by reactive ion etching, using the etching mask39made of alumina. In this case, a product formed through a plasma reaction between Cl2of the etching gas and iron or iron and cobalt of the magnetic layer deposits on the sidewalls of the magnetic layer that has been etched. As a result, during the etching, until the bottom portion formed through the etching reaches the neighborhood of the write gap layer26, the magnetic layer etched is likely to have the shape in which the width thereof increases as the distance to the lower portion of the magnetic layer decreases. However, the amount of the above-mentioned product formed through the plasma reaction extremely decreases when the bottom portion formed through the etching reaches the neighborhood of the write gap layer26. If the etching is further continued after the bottom portion reaches the write gap layer26, portions of the sidewalls of the magnetic layer etched, the portions being near the bottom portion, are then etched, and the magnetic layer etched finally has a shape in which the sidewalls of the magnetic layer etched form an angle of nearly 90 degrees with respect to the top surface of the write gap layer26. To form the magnetic layer having such a shape, it is required that the other magnetic layer below the write gap layer26would not be exposed during the etching until the magnetic layer etched has the above-mentioned shape. This is because, if the other magnetic layer below the write gap layer26is exposed during the etching, a product of a plasma reaction formed through the etching of the magnetic layer exposed deposits on the sidewalls of the magnetic layer etched.

Here, if the write gap layer26is made of a nonmagnetic inorganic material such as alumina, silicon carbide (SiC), or aluminum nitride (AlN), the etching rate of the write gap layer26is lower than that of the magnetic layer. It is thereby possible to prevent the other magnetic layer below the write gap layer26from being exposed during the etching until the magnetic layer etched has the above-mentioned shape. As a result, the sidewalls of the magnetic layer that has been etched form an angle of nearly 90 degrees with respect to the top surface of the write gap layer26.

The following are preferred conditions for etching the magnetic layer by reactive ion etching as described above. The pressure in the chamber (the degree of vacuum) is preferably 0.1 to 1.0 Pa. The temperature at which the etching is performed is preferably 200 to 300° C. The etching gas preferably includes Cl2, and more preferably includes BCl3and CO2, in addition to Cl2. The flow rate of Cl2of the etching gas is preferably 100 to 300 ccm. The flow rate of BCl3of the etching gas is preferably 50% of the flow rate of Cl2or lower. If the flow rate of BCl3is higher than 50% of the flow rate of Cl2, alumina is likely to be etched. The flow rate of CO2of the etching gas is preferably 10% of the flow rate of Cl2or lower. If the flow rate of CO2is higher than 10% of the flow rate of Cl2, the sidewalls of the magnetic layer form a greater angle with respect to the direction orthogonal to the top surface of the write gap layer26. The substrate bias for the etching is preferably 150 to 500 W.

For etching the magnetic layer by reactive ion etching as described above, the etching mask39is preferably made of a nonmagnetic inorganic material such as alumina, silicon carbide (SiC), or aluminum nitride (AlN), which is similar to the write gap layer26. This is because, as in the case of the write gap layer26, the etching rate of the etching mask39is lower than that of the magnetic layer when the magnetic layer made of a magnetic material including at least iron that is one of the group consisting of iron and cobalt, such as CoFeN or FeCo, is etched by reactive ion etching.

If the magnetic layer is etched by reactive ion etching and the yoke portion layer30g, the intermediate layer30cand the throat height defining layer30aare thereby formed as described above, the write gap layer26is then etched by ion beam etching, for example, using the throat height defining layer30aas a mask. Next, a photoresist mask (not shown) having an opening around the track width defining portion30A is formed. A portion of the fourth layer10fis etched by ion beam etching, for example, using the photoresist mask and the track width defining portion30A as masks. A trim structure is thereby formed.

According to the embodiment, the second coil19may be made by the following method, instead of the method described with reference toFIG. 3AtoFIG. 6A, andFIG. 3BtoFIG. 6B. In this method the insulating film17is formed in addition to the state shown inFIG. 2AandFIG. 2Bto cover the entire top surface of the layered structure. Next, an electrode film is formed to cover the entire top surface of the layered structure. On the electrode film the conductive layer19pmade of a metal such as Cu and having a thickness of 3 to 4 μm, for example, is formed by frame plating, for example. Next, portions of the electrode film except the portion below the conductive layer19pare removed by ion beam etching, for example. Next, an insulating layer made of alumina, for example, and having a thickness of 3 to 5 μm is formed to cover the entire top surface of the layered structure. The insulating layer is then polished by CMP, for example, so that the second layer10b, the coupling layer10cand the first coil13are exposed. The second coil19is thereby made up of the conductive layer19pand the electrode film remaining in the space between the second layer10band the first coil13, the space between the turns of the first coil13, and the space between the coupling layer10cand the first coil13.

The thin-film magnetic head according to the present embodiment comprises the air bearing surface42serving as a medium facing surface that faces toward a recording medium. The magnetic head further comprises the read head and the write head (the induction-type electromagnetic transducer).

The read head includes: the MR element5located near the air bearing surface42; the bottom shield layer3and the top shield layer8for shielding the MR element5; the bottom shield gap film4located between the MR element5and the bottom shield layer3; and the top shield gap film7located between the MR element5and the top shield layer8. The portions of the bottom shield layer3and the top shield layer8located on a side of the air bearing surface42are opposed to each other with the MR element5in between.

The write head comprises the bottom pole layer10and the top pole layer30that are magnetically coupled to each other and include the pole portions opposed to each other and located in the regions of the pole layers on the side of the air bearing surface42. The write head further comprises: the write gap layer26disposed between the pole portion of the bottom pole layer10and the pole portion of the top pole layer30; and the coils13and19. The coils13and19are provided such that at least part of each of the coils is disposed between the bottom pole layer10and the top pole layer30and insulated from the bottom pole layer10and the top pole layer30. The bottom pole layer10and the top pole layer30of the present embodiment correspond to the first pole layer and the second pole layer of the invention, respectively.

The bottom pole layer10includes the first layer10a, the second layer10b, the third layer10d, the fourth layer10f, and the coupling layers10c,10eand10g. The first layer10ais disposed to be opposed to the coils13and19. The second layer10bis disposed near the air bearing surface42and connected to the first layer10ain such a manner that the second layer10bprotrudes closer toward the top pole layer30than the first layer10a. The third layer10dis disposed near the air bearing surface42and connected to the second layer10bin such a manner that the third layer10dprotrudes closer toward the top pole layer30than the second layer10b. The fourth layer10fis disposed near the air bearing surface42and connected to the third layer10din such a manner that the fourth layer10fprotrudes closer toward the top pole layer30than the third layer10d.

The top pole layer30incorporates the throat height defining layer30athat is disposed adjacent to the write gap layer26and includes the end portion30a1for defining the throat height. The top pole layer30further incorporates: the intermediate layer30cdisposed on a side of the throat height defining layer30afarther from the write gap layer26; the yoke portion layers30eand30fdisposed on a side of the intermediate layer30cfarther from the throat height defining layer30a; and the coupling layers30band30d. The intermediate layer30cincludes the first track width defining portion for defining the track width. The yoke portion layers30eand30finclude the second track width defining portion30A for defining the track width. It is either possible that the entire intermediate layer30cforms the first track width defining portion having a uniform width or a portion of the intermediate layer30cclose to the air bearing surface42forms the first track width defining portion having a uniform width.

The width of each of the throat height defining layer30a, the track width defining portion of the intermediate layer30c, and the track width defining portion30A taken in the air bearing surface42is equal to the track width. The length of the intermediate layer30cis greater than the length of the throat height defining layer30a, and the length of the yoke portion layers30eand30fis greater than the length of the intermediate layer30c, each of the lengths being taken in the direction orthogonal to the air bearing surface42. The intermediate layer30cand the yoke portion layers30eand30fare flat layers. The intermediate layer30ccorresponds to the first track width defining layer of the invention. Each of the yoke portion layers30eand30fcorresponds to the second track width defining layer of the invention. The coupling layers10c,10e,10g,30band30dmake up the coupling section43for magnetically coupling the bottom pole layer10to the top pole layer30.

The fourth layer10fof the bottom pole layer10has a portion that faces toward the throat height defining layer30aof the top pole layer30, the write gap layer26being disposed in between. This portion is the pole portion of the bottom pole layer10. The throat height defining layer30ais the pole portion of the top pole layer30. As shown inFIG. 17A, throat height TH is the distance between the air bearing surface42and the end portion30a1of the throat height defining layer30a. Zero throat height level TH0is the level of the end portion30a1of the throat height defining layer30a. Each of the fourth layer10fand the throat height defining layer30apreferably has a saturation flux density of 2.4 T or greater.

As shown inFIG. 18, the thin-film coil of the embodiment includes the first coil13, the second coil19and the connecting layer21. The first coil13has turns part of which is disposed between the second layer10band the coupling layer10c. The second coil19has turns at least part of which is disposed between turns of the first coil13. The connecting layer21is disposed on a side of the third layer10dand connects the coil13to the coil19in series. Part of the turns of the second coil19is disposed between the second layer10band the coupling layer10c, too. The coils13and19are both flat whorl-shaped and disposed around the coupling portion43. The coils13and19may be both wound clockwise from the outer end to the inner end. The connecting layer21connects the connecting portion13aof the coil13to the connecting portion19bof the coil19at the minimum distance. The connecting layer21has a thickness smaller than the thickness of each of the coils13and19. The coils13and19and the connecting layer21are all made of a metal, such as Cu. The thin-film coil of the embodiment has seven turns although the invention is not limited to the seven-turn coil.

The method of manufacturing the thin-film magnetic head of the embodiment comprises the steps of: forming the bottom pole layer10; forming the thin-film coil (made up of the coils13and19and the connecting layer21) on the bottom pole layer10; and forming the write gap layer26on the pole portion of the bottom pole layer10.

The method further comprises the steps of: forming the magnetic layer27on the write gap layer26for forming the throat height defining layer30a; forming the etching mask28aon the magnetic layer27for forming the end portion30a1for defining the throat height in the magnetic layer27; and forming the end portion30a1for defining the throat height in the magnetic layer30apby selectively etching the magnetic layer27through the use of the etching mask28a, the magnetic layer30apbeing made up of the magnetic layer27etched.

The method of the embodiment further comprises the steps of: forming the nonmagnetic layer31so as to fill the etched portion of the magnetic layer27while the mask28ais left unremoved; removing the mask28aafter the nonmagnetic layer31is formed; and flattening the top surfaces of the magnetic layer30apand the nonmagnetic layer31by polishing such as CMP after the mask28ais removed, the magnetic layer30apbeing made up of the magnetic layer27etched.

The method of the embodiment further comprises the steps of: forming the magnetic layer33on the flattened top surfaces of the magnetic layer30apand the nonmagnetic layer31for forming the intermediate layer30c; forming the etching mask34aon the magnetic layer33for forming the end portion30c1of the magnetic layer33opposite to the air bearing surface42; and forming the end portion30c1of the magnetic layer30cpby selectively etching the magnetic layer33through the use of the etching mask34a, the magnetic layer30cpbeing made up of the magnetic layer33that has been etched.

The method further comprises the steps of: forming the nonmagnetic layer35so as to fill the etched portion of the magnetic layer33while the mask34ais left unremoved; removing the mask34aafter the nonmagnetic layer35is formed; and flattening the top surfaces of the magnetic layer30cpand the nonmagnetic layer35by polishing such as CMP after the mask34ais removed, the magnetic layer30cpbeing made up of the magnetic layer33etched.

The method further comprises the steps of: forming the yoke portion layers30eand30fon the flattened top surfaces of the magnetic layer30cpand the nonmagnetic layer35, the yoke portion layers30eand30fserving as the second track width defining layer; and etching the magnetic layers30cpand30ap, the write gap layer26and a portion of the fourth layer10fof the bottom pole layer10to align with the width of the track width defining portion30A through the use of the track width defining portion30A of the yoke portion layers30eand30fas a mask. Through this step the magnetic layer30cpis patterned to form the intermediate layer30c, and the magnetic layer30apis patterned to form the throat height defining layer30a. In addition, each of the portion of the fourth layer10f, the write gap layer26, the throat height defining layer30a, the intermediate layer30c, and the track width defining portion30A is made to have a width taken in the air bearing surface42that is equal to the track width.

According to the embodiment, in the step of forming the end portion30a1for defining the throat height in the magnetic layer30apby selectively etching the magnetic layer27, the magnetic layer30apbeing made up of the magnetic layer27etched, the write gap layer26is selectively etched to the level of the interface between the write gap layer26and the fourth layer10fof the bottom pole layer10.

According to the embodiment, the throat height is defined by the throat height defining layer30aof the top pole layer30. It is therefore not necessary to form a stepped portion in the bottom pole layer10for defining the throat height. As a result, according to the embodiment, it is possible to prevent an extreme reduction in the volume of the portion of the bottom pole layer10sandwiched between the side portions forming the trim structure, and to prevent a sudden decrease in the cross-sectional area of the magnetic path near the interface between the above-mentioned portion of the bottom pole layer10and the other portion.

According to the embodiment, the throat height defining layer30a, the intermediate layer30cand the yoke portion layers30eand30fare stacked one by one on the write gap layer26. Each of the throat height defining layer30a, the intermediate layer30cand the track width defining portion30A has a width taken in the air bearing surface42that is equal to the track width. In addition, the length of the intermediate layer30ctaken in the direction orthogonal to the air bearing surface42is greater than the length of the throat height defining layer30a. The length of the yoke portion layers30eand30ftaken in the direction orthogonal to the air bearing surface42is greater than the length of the intermediate layer30c. According to the embodiment, these features achieve an increase in the distance between the top pole layer30and the bottom pole layer10in the region farther from the air bearing surface42than the zero throat height level TH0. In addition, the cross-sectional area of the magnetic path of the top pole layer30near the air bearing surface42is made to gradually change. According to the embodiment, these features prevent saturation and leakage of flux halfway through the magnetic path. The overwrite property is thereby improved.

According to the embodiment, it is possible to prevent an extreme reduction in the volume of the portion of the bottom pole layer10sandwiched between the side portions forming the trim structure. As a result, it is possible to prevent leakage of magnetic flux from the neighborhood of the bottom of the stepped portion of the trim structure that belongs to the end face of the bottom pole layer10exposed from the air bearing surface42toward the recording medium, in particular. It is thereby possible to prevent side write and side erase.

In the air bearing surface42the throat height defining layer30a, the intermediate layer30cand the yoke portion layers30eand30fhave equal widths. Therefore, there is no sudden variation in width in the end face of the top pole layer30exposed from the air bearing surface42. As a result, an amount of flux leakage from the end face of the top pole layer30exposed from the air bearing surface42is small, and it is possible to prevent a reduction in overwrite property and to prevent the occurrences of side write and side erase.

According to the embodiment, the nonmagnetic layer31is formed by lift-off so as to fill the etched portions of the magnetic layer27and the write gap layer26. It is therefore possible to flatten the top surfaces of the throat height defining layer30aand the nonmagnetic layer31by a small amount of polishing. It is thereby possible to determine the thickness of the pole portion of the top pole layer30with accuracy. Similarly, according to the embodiment, the nonmagnetic layer35is formed by lift-off so as to fill the etched portion of the magnetic layer33. It is therefore possible to flatten the top surfaces of the intermediate layer30cand the nonmagnetic layer35by a small amount of polishing. It is thereby possible to determine the thickness of the intermediate layer30cwith accuracy. Owing to these features, according to the embodiment, the thickness of the top pole layer30exposed from the air bearing surface42is controlled with accuracy. As a result, the writing characteristics of the thin-film magnetic head are easily controlled with accuracy. The nonmagnetic layer31may be formed such that the top surface thereof is disposed in the level almost the same as the level of the top surface of the throat height defining layer30a. It is thereby possible to omit the step of flattening the top surfaces of the magnetic layer30apand the nonmagnetic layer31by polishing. Similarly, the nonmagnetic layer35may be formed such that the top surface thereof is disposed in the level almost the same as the level of the top surface of the intermediate layer30c. It is thereby possible to omit the step of flattening the top surfaces of the magnetic layer30cpand the nonmagnetic layer35by polishing.

According to the embodiment, the yoke portion layers30eand30fof the top pole layer30are flat layers formed on the nearly flat base layer. As a result, according to the embodiment, it is possible to form the track width defining portion30A that is small in size with accuracy. It is thereby possible to reduce the track width and improve the writing density.

According to the embodiment, the second layer10b, the third layer10d, the fourth layer10fand the top pole layer30may be made of a high saturation flux density material. It is thereby possible to prevent a saturation of flux halfway through the magnetic path. To achieve this, it is particularly effective that the fourth layer10fand the throat height defining layer30aare made of a high saturation flux density material having a saturation flux density of 2.4 T or greater. It is thereby possible to use the magnetomotive force generated by the thin-film coil for writing with efficiency. It is thus possible to achieve the write head having an excellent overwrite property.

According to the embodiment, the first coil13is formed on the first layer10ahaving an entirely flat top surface. It is thus possible to form the first coil13that is thick but small in size with accuracy. According to the embodiment, the second coil19is formed such that at least part of the turns of the second coil19is disposed between the turns of the first coil13. It is thereby possible to form the second coil19that is thick but small in size with accuracy, too. According to the embodiment, it is the thin insulating film17that separates the second layer10bfrom the second coil19, the turns of the first coil13from the turns of the second coil19, and the coupling layer10cfrom the second coil19. It is thereby possible that the space between the second layer10band the second coil19, the space between the turns of the first coil13and the turns of the second coil19, and the space between the coupling layer10cand the second coil19are made very small.

The foregoing features of the embodiment allow the coils13and19to be thick and the yoke length to be short. It is thereby possible to reduce the resistance of the thin-film coil while the yoke length is reduced, that is, the magnetic path length is reduced. As a result, according to the embodiment of the invention, it is possible to achieve the thin-film magnetic head having a reduced magnetic path length and thus having excellent writing characteristics in a high frequency band, and having the thin-film coil with a low resistance.

According to the embodiment, an outer portion of the thin-film coil is disposed adjacent to the second layer10b, the thin insulating film17being located in between. That is, the thin-film coil is disposed near the air bearing surface42. As a result, according to the embodiment, it is possible to utilize the magnetomotive force generated by the thin-film coil for writing with efficiency. It is thereby possible to achieve the write head having an excellent overwrite property.

According to the embodiment, a coil for connecting the coil13to the coil19in series may be provided in place of the connecting layer21. It is thereby possible to increase the number of turns of the thin-film coil without increasing the yoke length while an increase in resistance of the thin-film coil is prevented.

Second Embodiment

Reference is now made toFIG. 21AandFIG. 21Bto describe a thin-film magnetic head and a method of manufacturing the same of a second embodiment of the invention.FIG. 21AandFIG. 21Bare cross sections of the thin-film magnetic head of the embodiment.FIG. 21Ais a cross section orthogonal to the air bearing surface and the top surface of the substrate.FIG. 21Bis a cross section of the pole portions parallel to the air bearing surface.

The embodiment includes the step of forming the end portion30a1for defining the throat height in the magnetic layer30apby selectively etching the magnetic layer27, the magnetic layer30apbeing made up of the magnetic layer27etched. In this step the write gap layer26is selectively etched to the level somewhere in the middle of the thickness of the write gap layer26. According to the embodiment, the nonmagnetic layer31is formed in a self-aligned manner so as to fill the etched portions of the magnetic layer27and the write gap layer26.

In the above-mentioned step it is possible that etching is stopped in the level at the interface between the magnetic layer27and the write gap layer26so as not to etch the write gap layer26. The remainder of configuration, function and effects of the second embodiment are similar to those of the first embodiment.

The present invention is not limited to the foregoing embodiments but may be practiced in still other ways. For example, the thin-film coil incorporating the coils13and19and the connecting layer21is provided in the embodiments. However, the thin-film coil of the invention is not limited to this coil but may be a typical thin-film coil made up of a flat whorl-shaped coil having one layer or more.

The invention is also applicable to a thin-film magnetic head dedicated to writing that has an induction-type electromagnetic transducer only, or a thin-film magnetic head that performs writing and reading with an induction-type electromagnetic transducer.