JP2009157977A - Method for manufacturing magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a reproducing magnetic head with a narrow track width, by which a dimension not more than a resolution limit of lithography can be materialized inexpensively. <P>SOLUTION: Working with the narrow track width is conducted by a sidewall mask method using a film deposited on a sidewall of a dummy pattern as a mask. Also an etch stopper layer and a release layer are formed beforehand as lower layers of a film for forming the sidewall, and removal of redundant portions is conducted by using a lift-off. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a magnetic head, and more particularly to a method for manufacturing a magnetoresistive element as a reproducing sensor for a magnetic head mounted on a magnetic recording / reproducing apparatus.

  In order to increase the recording density of a hard disk drive (HDD), the size of the magnetic head is becoming finer year by year. In the past, inductive heads that used both a recording head and a reproducing head were the mainstream, but the current mainstream is a recording / reproducing head with a separate recording head and reproducing head. The recording head is an induction head for writing information by an induction magnetic field generated by a coil, but the reproduction head is a GMR head or TMR head using a spin valve as a magnetic sensor. FIG. 2 shows a schematic diagram of a recording / reproducing separation type head. FIG. 3 shows an enlarged view of the reproducing head portion. FIG. 3 is seen from the surface (ABS surface, the surface seen from A in FIG. 2) facing the magnetic disk medium. The magnetic head is formed on an AlTiC (alumina-titanium carbide) substrate using a microfabrication technique. In addition, illustration of a board | substrate part is also abbreviate | omitted also on subsequent drawings. The lower shield layer 3 and the upper shield layer 4 made of permalloy also serve as electrodes, and magnetism is detected by energizing a multilayer spin valve magnetoresistive film 5 formed therebetween. An alumina insulating film 11 and a permanent magnet film 6 for applying a bias magnetic field are disposed adjacent to the magnetoresistive effect film 5 for detecting magnetism.

  From the viewpoint of the reproducing head, the important factors that determine the recording density are the track width 12 and the gap length 13. The track width determines the resolution in the track width direction of the reproducing head, and the gap length determines the resolution in the track length direction for scanning the head. In order to improve the recording density, the introduction of advanced lithography technology for forming a narrower track width pattern and the reduction of the total thickness of the magnetoresistive effect film for reducing the gap length have been performed.

  Since the track width of the read head is the smallest processing dimension in the magnetic head process, the highest possible lithography technology has been introduced at that time. The resolution limit of lithography is mainly determined by the wavelength of the light source, and fine patterns can be formed with shorter wavelengths. Therefore, the light source has shifted from i-line (wavelength 365 nm) to KrF excimer (wavelength 248 nm), ArF excimer (193 nm), and short wavelength ultraviolet region. In the process, technological barriers increase with generations, and the technological limits are approaching. Although the minimum resolution size in the dry exposure type ArF excimer lithography technology at the leading edge is considered to be 60 to 50 nm, the track width of the reproducing magnetic head required in 2010 is predicted to be 30 nm, and the performance is insufficient. Even if the next generation immersion type ArF excimer lithography technology is introduced, the minimum resolution dimension is predicted to be 45 to 40 nm, and another breakthrough technology is considered necessary. On the other hand, in addition to technical limits, economic limits are also approaching. The price of the latest lithography apparatus is billions of yen / unit for dry exposure type ArF, and it is said that it is twice that for immersion type ArF, and it is exceeding the economic limit allowed as a magnetic head processing apparatus as a part of HDD. In order to maintain and accelerate the pace of HDD recording density improvement, a new track width microfabrication process that can exceed the lithography limit at low cost is required.

  In response to these problems, a method of forming a narrow track width by using a sidewall mask using a film deposited on the sidewall of a dummy pattern as a mask instead of a method of forming a track width using a pattern formed by lithography as a mask. Is disclosed in Patent Document 1. Although not a reproducing magnetic head, Patent Document 2 discloses a method of using a sidewall as a main magnetic pole instead of as a mask in a method of manufacturing a recording magnetic head. In any case, since the deposited film thickness on the side wall becomes the width of the track, in principle, it is possible to form a track with a fine pattern of several nm below the wavelength limit of lithography.

US Pat. No. 7,134,185 JP 2002-175606 A

  A technique itself for forming a pattern below the resolution limit of lithography using a mask using a sidewall structure has been known for microfabrication of semiconductors. However, this method has a disadvantage that the pattern size that can be formed simultaneously is limited to only one type determined by the sidewall film thickness, and there are almost no practical examples of semiconductor products that form various patterns. On the other hand, the processing of the magnetic head is suitable for the sidewall mask method because it is only necessary to process one type of track width.

  However, the magnetic head process, particularly the track forming process of a reproducing head for processing a fine dimension, has a thickness of several nm or less as the uppermost layer of the magnetoresistive film in which the film is embedded as shown in FIGS. It is necessary to make a state exposed with high accuracy in order. This is because the function of the magnetoresistive film is not impaired and the required accuracy of the gap length 13 that determines the resolution. For this reason, even if the sidewall mask method is simply transferred from the semiconductor, the hard mask used for the sidewall cannot be accurately removed on the magnetoresistive film, and an insulating film or permanent magnet film is embedded in the surrounding area. Difficult to make. This is the difference from semiconductors.

  Another difference is that the manufacturing process temperature of the magnetic head is very low at 300 ° C. or less compared to 450 ° C. to 1100 ° C., which is typical in the semiconductor diffusion process, and the restrictions on the film type are large, especially suitable for sidewalls. Many CVD (Chemical Vapor Deposition) methods that allow conformal deposition may not be available. In addition, since the film to be processed of the magnetic head is a metal multilayer film, it is difficult to perform dry etching, which is generally used in semiconductors, and the use of physical ion milling may limit the milling resistance of the sidewall material as a mask. Can be mentioned. For these reasons, the method using the side wall mask even in the magnetic head has not been used in actual manufacturing until now. Here, in the magnetic head field, there is a problem in the method of using a sidewall in a magnetic head for recording as disclosed in Patent Document 1 and Patent Document 2 that disclose a method of using a sidewall mask.

  First, the method of using a sidewall mask in the track width processing of the reproducing magnetic head in Patent Document 1 has a problem that the track shape is asymmetrically cut. This is because only the base on one side of the sidewall without resist is exposed by the etch back when forming the side wall structure, but the ion milling rate is high because the base is a nonmagnetic material such as copper. This is because only the base of the track is shaved and the track shape becomes asymmetrical. This is not preferable because asymmetry appears in the sensor characteristics. Further, after cutting the track width pattern, obliquely incident ion milling is used in order to remove unnecessary portions on the magnetoresistive film including the sidewall mask. There are two problems with this removal by ion milling. First, obliquely incident ion milling has insufficient convexity selectivity, and the flat part to be protected is shaved at a high rate ratio of several percent while the upper part to be removed is shaved, resulting in shape controllability and variations. Secondly, it does not reach the practical level, and secondly, ion milling reattaches everywhere in the vicinity at the time of removal, but this may lead to defects such as an undesirable short circuit with the magnetoresistive film. It is done.

  Furthermore, the method of Patent Document 1 uses a soft magnetic material as a sidewall material, and after using this as a sidewall mask, the remaining portion is used as it is as a part of the upper shield of the magnetoresistive film. There's a problem. First, the ion milling rate such as permalloy, which has good properties as a soft magnetic material, is not as selective as the rate of the magnetoresistive film to be processed, and is not suitable as a mask material. There is a problem from the viewpoint of processing that conformal film formation on the side wall is difficult because it is limited to sputtering. In the method of Patent Document 1 in which a soft magnetic mask having a dimension equal to the track width is left immediately above the magnetoresistive film, the upper shield in the vicinity of the magnetoresistive film is only on the track, and an effective gap important for resolution is obtained. There is also a problem in magnetic properties that the length increases. This is because the average upper shield of the reproducing magnetic head as a whole becomes far away because of the structure in which an insulating film and a permanent magnet film are arranged near the outside of the remaining portion of the soft magnetic mask.

  In addition, a method of processing a narrow track width by forming the main magnetic pole itself as a sidewall structure in a manufacturing process of a recording magnetic head, as typified by Patent Document 2, is also known. In this method, a problem arises because the sidewall is not used as a mask, but as a main magnetic pole itself that requires excellent magnetic properties. Specifically, it is difficult to achieve both conformability for forming a sidewall structure, workability such as a desired taper shape, and magnetic characteristics as a main magnetic pole material. Because of these major problems, the method using sidewalls has not been put to practical use in the field of magnetic heads.

  In view of such problems, the present invention is a method for forming a detection part pattern of a magnetoresistive effect element, particularly a track of a reproducing magnetic head, by using a sidewall mask capable of forming a dimension below the resolution limit of lithography at a low cost. A method is provided.

  First, instead of a conventional method of forming a track width using a pattern formed by lithography as a mask, processing of a narrow track width is performed by a sidewall mask method using a film deposited on the sidewall of a dummy pattern as a mask. Since the deposited film thickness on the side wall of the dummy pattern becomes the width of the mask, in principle, it is possible to form a fine pattern of several nm below the lithography wavelength limit.

  Here, prior to the formation of the sidewall mask, an etch stopper layer and a release layer are preferably formed in advance under the sidewall formation film. With the etch stopper layer, overetching of the surface of the flat portion not used as a mask can be prevented in the process of forming a sidewall formation film and performing etch back. The peeling layer is used for lift-off for removing unnecessary photoresist, insulating film, and hard bias film immediately above the formed magnetoresistive film pattern. In Patent Document 1, a method based on ion incidence such as oblique milling is used in this unnecessary portion removing step, but the present invention solves the above-described problem by using lift-off. In the method of Patent Document 1, it is necessary to use a conductive soft magnetic material for the sidewall, and an etch stop layer or a release layer of an insulator cannot be introduced. If the lift-off property is insufficient due to the miniaturization of the processing dimension accompanying the increase in recording density or the thickening of the embedded film, a solution using CMP lift-off with enhanced lift-off property with the assistance of CMP (Chemical Mechanical Polishing) is also included. Present. Note that both the etch stopper layer and the release layer are not necessarily formed, and only one of them may be formed.

  In the method presented here, since the sidewall is applied only as a mask, it is not necessary to achieve compatibility with magnetic characteristics, and high-precision microfabrication is possible.

  As an effect of the present invention, in the magnetic head forming process, a fine pattern exceeding the physical limit of lithography determined by the light source wavelength can be formed. Specifically, it is possible to form even a pattern of several nm or less in principle, which is less than the minimum processing dimension of 45 to 40 nm by the highest level lithography currently available. Since the pattern width is determined by the deposited film thickness of the mask material, there is no restriction on the pattern width. Any size can be formed.

  Hereinafter, embodiments of the present invention will be described.

  First, the first embodiment will be described. FIG. 5 shows a wafer cross-sectional view at the stage where a permalloy 15 is formed as a lower shield on the AlTiC substrate and patterned in the wafer manufacturing process of the reproducing magnetic head. FIG. 5A is a top view of the wafer, and FIG. 5B is a cross-sectional view of the wafer. The cross section corresponds to the ABS surface (air bearing surface surface, medium facing surface) after completion of the magnetic head. Also in the following figures, the left figure (a) shows a wafer top view, and the right figure (b) shows a wafer cross-sectional view. Since the process before this is the same as the manufacturing process of a reproducing magnetic head using a general magnetoresistive element, the description is omitted.

  FIG. 6 shows a stage in which a multilayer magnetoresistive film 16 is deposited after planarizing the surface irregularities during the formation of the lower shield by CMP. The type of the magnetoresistive effect film 16 is a spin valve element utilizing the GMR effect, and is a CPP-GMR type magnetoresistive effect element in which a sense current is passed perpendicularly to the wafer surface. The magnetoresistive film 16 has a multilayer structure, and is divided into functional structures of an underlayer 17, an antiferromagnetic layer 18, a pinned layer 19, an intermediate layer 20, a free layer 21, and a cap layer 22 as shown in FIG. Each structure is composed of one or several kinds of films. The total film thickness of the magnetoresistive effect film is 40 nm. Note that the magnetoresistive effect element used here is not detracted from the spirit of the present invention even if it is of another type, such as a TMR type spin valve.

  FIG. 8 shows a stage in which the pattern 8 in the element height direction is formed by the photoresist 7 and the magnetoresistive film 16 is removed by ion milling. FIG. 9 shows a stage in which 45 nm of alumina 9 is deposited as an insulating film, and unnecessary portions on the magnetoresistive film 16 are removed by lift-off.

  Here, as shown in FIG. 10, an etch stopper layer 23 and a release layer 24 are deposited to form a dummy pattern 25. A diamond-like carbon film is used for the etch stopper layer. A polyimide film having a thickness of 60 nm is used as a peeling layer, and an i-line photoresist is applied to the film to form a dummy pattern by 0.5 μm, and a desired shape is transferred using i-line photolithography. Since it is not a fine pattern, a photoresist having a thick film thickness of 0.5 μm, high etching resistance, and low sidewall roughness can be applied to the photoresist in this step. Further, the deposition order of the etch stopper layer and the release layer may be switched.

Subsequently, when an alumina film (film for forming a sidewall) 26 serving as a sidewall mask is deposited to 100 nm by sputtering, the state shown in FIG. 11 is obtained. Since the deposition rate on the side wall of the pattern is lower than that on the plane of the wafer, the deposition amount is adjusted so that the desired thickness is 30 nm on the side wall. Subsequently, the state shown in FIG. 12 is obtained when the etch back is sufficiently performed so as to leave only the sidewalls 27 by anisotropic etch back using ion milling mainly incident in the wafer vertical direction. Here, since the etch stopper film 23 is a diamond-like carbon film, the ion milling rate is sufficiently low with respect to the sidewall material, so that the milling can be stopped with good controllability while protecting the upper surface of the magnetoresistive film 16. I can do it. At the same time, the surface of the photoresist 7 is also exposed. Although ion milling is used for etch back here, dry etching that is more excellent in anisotropic processing may be used. In the case of dry etching, if an SiO ₂ film is used instead of the alumina film, the etching rate is high and processing is easy.

  Next, when the photoresist 7 and the polyimide film 24 and the etch stopper film 23 of the exposed peeling layer are ashed and removed by oxygen plasma treatment using asher, the state shown in FIG. 13 is obtained. In this state, the sidewall mask of the track width pattern of the reproducing magnetic head is completed. The width of the sidewall mask 28 is only 30 nm, and this dimension is below the resolution limit of a state-of-the-art lithography apparatus.

  Thereafter, using this as a mask, the track width pattern is transferred to the magnetoresistive film 16 by ion milling to process the track width. Since the height of the sidewall mask is sufficiently high at about 0.4 μm and the milling resistance of the mask itself is high, sufficient resistance can be secured as a mask of the magnetoresistive film 16 having a thickness of 40 nm. The state after milling of the track width pattern is shown in FIG.

  Next, a separation portion for separating the magnetoresistive film is formed. Here, the separation part is composed of an insulating film and a permanent magnet film. First, alumina 11 as an insulating film is deposited by sputtering to 8 nm. Further, when the alloy film 6 of cobalt chromium platinum is deposited by ion beam sputtering so as to have the same height as the magnetoresistive film 16 as a permanent magnet film, the state shown in FIG. 15 is obtained. Baking is performed in this state, and the unnecessary portion 29 above the magnetoresistive film is lifted off from the release layer 24, resulting in FIG. A bird's eye view is shown in FIG.

  When the sidewall mask of the present invention is used, a sidewall is formed along the entire periphery of the dummy pattern, so that a characteristic sidewall trace 30 remains. However, this portion is made of a stable insulator and is not particularly problematic because it is not used as a magnetic detection element. Through the above steps, a track width pattern having a width of 30 nm, which is below the resolution limit of lithography, can be formed using only a low-cost old-generation apparatus.

  In principle, in the method of the present embodiment, a permanent magnet film made of a conductive metal is embedded on the entire surface of the wafer other than under the sidewall. In a later process, this metal film may cause a short circuit failure at an unexpected location. As a countermeasure, a pattern covering the magnetoresistive effect element portion is formed by lithography in advance, unnecessary metal film is removed by ion milling, and then the alumina of the insulating film is backfilled, and unnecessary portions on the resist are lifted off. Add a process. Thereafter, after cleaning the upper portion of the magnetoresistive effect film 16, a permalloy serving as an upper shield is deposited, and after a wiring process and the like, the recording element portion is laminated. Since details are the same as those in a general magnetic head manufacturing process, description thereof is omitted.

  A second embodiment will be described. This embodiment is the best method when the lift-off property is insufficient due to the miniaturization of the processing dimensions and the thickening of the sidewall deposited film in the lift-off part.

  The processing steps up to the track width shown in FIG. 14 are the same as those in the first embodiment. Next, alumina 11 as an insulating film and cobalt chromium platinum alloy film 6 as a permanent magnet film are deposited, and the periphery of the track is backfilled. In this step, when a deposition method is used in which the magnetic characteristics are prioritized and the sidewall deposition film thickness of the permanent magnet film is thick, the shape shown in FIG. 18 is obtained, and the rigid sidewall film 31 makes it difficult to lift off. In this case, in addition to baking and normal jet lift-off, CMP is performed to remove the unnecessary portion 29.

  Physical processing such as CMP has not been adopted so far due to damage to the magnetoresistive film and reduction of the film on the top of the permanent magnet film. Here, the following solution is used. As a first point, a diamond-like carbon film 23 that functions as a protective film against CMP is previously deposited on the magnetoresistive film with a thickness of 10 nm. As described above, this also serves as an etch stopper for the sidewall mask. Secondly, a diamond-like carbon film 32 is again deposited with a thickness of 18 nm for the purpose of preventing film loss after the permanent magnet film is deposited. At the time of CMP lift-off, the diamond-like carbon film 32 becomes a CMP protective film and prevents film loss (dishing) on the permanent magnet film. In CMP, alumina slurry of fine abrasive grains is used to prevent damage to the magnetoresistive film.

  FIG. 19 shows a state where the CMP lift-off is performed. Thereafter, oxygen plasma treatment is performed to remove the remaining diamond-like carbon films 23 and 32. The subsequent steps are the same as in the first embodiment.

  A third embodiment will be described. In this embodiment, a new atomic layer deposition (ALD) method is used as a method for depositing the sidewall mask film. The process up to the formation of the dummy pattern 25 shown in FIG. 10 is the same as that of the first embodiment. In this state, an alumina film is formed by ALD instead of sputtering.

  ALD is a method in which precursor material is adsorbed on the surface, and the supplied gas reacts on the surface and uses a process in which saturation is completed. Is repeated to form a film having a desired film thickness. For example, when depositing alumina, trimethylaluminum and ozone or water are used as source gases.

  ALD is characterized by a very conformal film formation that has almost the same film thickness all over the wafer plane and the side walls of the dummy pattern. Conventionally, in the processing of magnetic heads, the upper limit temperature of the process is 300 ° C. or less due to the heat resistance of the magnetic metal film, so the CVD (process temperature 400 to 1000 ° C.), which is a conformal film formation method used in the semiconductor field, is applied. could not. Sputtering, which is a low-temperature film-forming method, could be brought close to conformal by contriving the conditions, but a complete conformal film was made possible for the first time by ALD.

  FIG. 20 shows the shape after sidewall film formation by ALD. The amount of ALD alumina deposited is 30 nm, which is necessary for the side wall mask. Since the film thickness on the plane is the same as that on the side wall, the deposited film thickness required for forming the side wall mask can be reduced, and there is an advantage that the amount of subsequent etchback is small.

  In the etch back by ion milling, an undesirable redeposition 33 may occur on the sidewall of the sidewall as shown in FIG. When ALD is used, reattachment can be suppressed to the minimum, and the dimensions of the sidewall mask can be formed with good controllability as designed. Since the subsequent steps are the same as those in the first embodiment, description thereof is omitted.

  A fourth embodiment will be described. The present embodiment is a method in which the formation order of the element height pattern and the formation order of the track width pattern are interchanged with respect to the first embodiment.

  The steps up to the stage of FIG. 6 where the magnetoresistive film is deposited are the same as in the first embodiment. From here, the track width pattern is first formed by the same method as in the first embodiment. FIG. 22 shows a stage in which an etch stopper film 23 is deposited with a thickness of 10 nm, a release layer polyimide film 24 is deposited with a thickness of 60 nm, and a dummy pattern 25 for forming a track width pattern is formed using i-line photolithography. Next, when 30 nm of ALD alumina 34 is deposited, the state shown in FIG. 23 is obtained. Subsequently, when the anisotropic etch back using ion milling is sufficiently performed to leave only the sidewall 27, the shape shown in FIG. 24 is obtained. At the same time, the surface of the photoresist 7 having the dummy pattern is also exposed.

  Next, when the photoresist 7 and the polyimide film 24 and the etch stopper 23 of the exposed peeling layer are ashed using oxygen plasma treatment by asher and removed, the state shown in FIG. 25 is obtained. Here, a sidewall mask having a track width pattern is completed. FIG. 26 shows a state in which the track width pattern is transferred to the magnetoresistive effect film 16 by ion milling using the sidewall mask 28 and the track width is processed.

  Next, alumina 11 as an insulating film is deposited by sputtering. Further, when an alloy film 6 of cobalt chromium platinum is deposited as a permanent magnet film and a diamond-like carbon film 32 is deposited as a CMP protective film by ion beam sputtering, the state shown in FIG. 27 is obtained. After baking and jet lift-off in this state, the unnecessary portion 29 above the magnetoresistive film is completely lifted off from the release layer 24 by CMP, resulting in FIG.

  Next, an element height pattern is formed. As shown in FIG. 29, after an etch stopper layer 23 and a release layer polyimide film 24 are deposited, a photoresist 7 is applied and an element height pattern is formed by lithography. When the unnecessary permanent magnet film 6 and magnetoresistive film 16 are removed by ion milling using this resist as a mask, the state shown in FIG. 30 is obtained. Here, alumina 9 is deposited as an insulating film, and a diamond-like carbon film is deposited as a CMP protective film. When bake and jet lift-off, lift-off by CMP and oxygen plasma treatment are performed, the state shown in FIG. 31 is obtained.

  Thus far, the track width pattern is formed. A bird's eye view is shown in FIG. Similar to the first embodiment, a characteristic sidewall trace 30 remains along the entire periphery of the dummy pattern. However, this part is covered with a stable insulator, and there is no particular problem. The method of this embodiment has a feature that the traces are smaller than those of the first embodiment.

  Next, the effect of the method of forming the track width pattern before the element height as in the fourth embodiment will be described. First, since the track width pattern having the minimum processing dimension is first formed in a flat state, there is an advantage that the processing accuracy is improved. In particular, there is an advantage that the track width can be processed with few steps at the element height zero position 35 in FIG.

  As a second point, when the track width pattern is formed first, an advantage is that an insulator is embedded in the entire surface of the wafer other than the magnetoresistive effect element portion when a series of processing is completed. If the element height pattern is first formed as in the first embodiment, a permanent magnet film made of a conductive metal remains on the entire wafer surface except for the magnetoresistive element portion. Therefore, as described above, it is necessary to add an unnecessary metal film removal step for preventing an unexpected short-circuit failure. This is because, in the method using the sidewall mask, since the mask is generated only as the sidewall around the dummy pattern, the permanent magnet film is deposited on the entire surface of the wafer other than the sidewall pattern after forming the track width. This is because it cannot be avoided in principle. In the method of the fourth embodiment in which the track width pattern processing is performed first, an unnecessary metal film can be replaced with an insulating film in the step of embedding the insulating film in the subsequent device height pattern processing, and thus the process is omitted. it can. However, since the entire surface of the wafer is covered with an insulating film, an electrode pad drilling process for electrically connecting the lower shield etc. to the upper part is necessary, but this can be combined with other processes by devising it. .

  A fifth embodiment will be described. This embodiment is an application example to an element in which a method using a side wall mask is inevitably required, and an extremely narrow track width and an extremely thick magnetoresistive film to be processed.

  FIG. 33 shows a structural diagram of the differential read magnetic head used in this embodiment. The differential read magnetic head has a structure in which two spin valve elements, which are magnetoresistive elements of a normal read magnetic head, are vertically reversed and stacked vertically. That is, the free layers of the upper and lower spin valve elements are arranged symmetrically so as to sandwich the middle intermediate layer. In addition, the magnetizations of the fixed layers of the upper and lower spin valve elements are designed to be opposite to each other. The difference in output from the upper and lower spin valve elements becomes a differential signal that captures the change in the external magnetic field. Since the distance between the free layers of the upper and lower spin valves determines the resolution in the film thickness direction, it has the distinctive feature that the resolution is high even if the entire magnetoresistive film is thick. As a result, it is expected as a candidate for the next generation magnetoresistive effect element.

  In order to take advantage of this differential read head, the track width must be extremely small at the same time. However, from the viewpoint of the processing process, the combination of an extremely narrow track and a thick magnetoresistive film is the least compatible. The narrower the track width pattern, the more advanced lithography of the short wavelength light source is necessary, but the thinner the resist corresponding to the fine dimensions, the poorer the etching resistance, and the thick film processing becomes impossible. FIG. 33 shows the dimensions of the differential read magnetic head. As for the next generation, the track width is as extremely narrow as 20 nm, while the thickness of the magnetoresistive film is 75 nm, which is about twice as large as usual. Photoresist such as immersion ArF has a thickness of only about 150 nm and has low ion milling resistance. Therefore, the resist disappears before processing is completed for a 75 nm film to be processed. As a solution, a two-stage mask method in which a hard mask is laid below is often used in the semiconductor field. However, since ion milling used in a magnetic head has a low selectivity with respect to a material type compared to dry etching of a semiconductor, a two-stage mask method using a selectivity difference is not effective. As the only possible option, the method using the sidewall mask of the present invention is effective.

  The flow when a differential read head structure is formed using a sidewall mask is shown below. FIG. 1 shows a stage in which a sidewall mask 28 made of ALD alumina having a width of 20 nm is formed on the thick magnetoresistive film 16. Since the height of the sidewall mask is 0.4 μm and the material is alumina with high milling resistance, a sufficient margin for processing a thick magnetoresistive film with a film thickness of 75 nm is secured. FIG. 34 shows a stage where the magnetoresistive film is removed and the insulating film 11, the permanent magnet film 6, and the CMP protective film 32 are deposited. If baking, jet lift-off, and CMP lift-off are performed here, the shape shown in FIG. 35 is obtained. An extremely narrow track and thick-film differential read magnetic head can be formed with a sufficient process margin. Since the subsequent flow is the same as the manufacturing process of a general reproducing magnetic head, the description is omitted.

  A sixth embodiment will be described. This embodiment is a modification in which the release layer is omitted from the first embodiment.

  The steps up to the formation of the element height pattern shown in FIG. 9 are the same as those in the first embodiment. Next, as shown in FIG. 36, an etch stopper layer 23 is deposited and a dummy pattern 25 is formed. A diamond-like carbon film is used for the etch stopper layer 23. As in the first embodiment, an alumina sidewall mask is formed on the sidewall of the dummy pattern. During the etch back for forming the sidewall, the upper surface of the magnetoresistive film is protected by the etch stopper layer. When the dummy pattern is removed, and the exposed etch stopper layer is ashed using oxygen plasma treatment by an asher and removed, the state shown in FIG. 37 is obtained.

  When a track width pattern is formed by ion milling, an alumina insulating film and a permanent magnet film are deposited, and a diamond-like carbon film 36 is deposited as a CMP stopper layer, the state shown in FIG. 38 is obtained. When CMP is performed here, only an unnecessary portion 29 on the magnetoresistive film upper portion which is a small area line pattern can be polished and removed by the convexity selectivity of the CMP processing. Since a hard diamond-like carbon film works as a protective layer on the magnetoresistive film and the permanent magnet film, damage such as excessive polishing (dishing) is not caused even during CMP overpolishing. FIG. 39 shows a state in which CMP is performed and the surplus diamond-like carbon film is removed by ashing. When this method is used, the peeling layer can be omitted and the manufacturing process can be simplified.

  A seventh embodiment will be described. The present embodiment is a modification in which the etch stopper layer is omitted from the first embodiment.

  The steps up to the formation of the element height pattern shown in FIG. 9 are the same as those in the first embodiment. Next, as shown in FIG. 40, a release layer 24 is deposited, and a dummy pattern 25 is formed. A polyimide film is used for the release layer. The film thickness of polyimide is 120 nm, which is twice that of the first embodiment. Subsequently, as in the first embodiment, an alumina sidewall mask is formed on the sidewall of the dummy pattern. In the etch back for forming the sidewall, the etching conditions are adjusted so that the thickened polyimide film remains. Thereby, the upper surface of the magnetoresistive film is protected. When the dummy pattern is removed, the exposed polyimide film is ashed using oxygen plasma treatment using an asher, and removed, the state shown in FIG. 41 is obtained.

  When a track width pattern is formed by ion milling and an alumina insulating film and a permanent magnet film are deposited, the state shown in FIG. 42 is obtained. Baking is performed in this state, and the unnecessary portion 29 above the magnetoresistive film is lifted off from the release layer 24, resulting in FIG. By using this method, the etching stopper layer can be omitted and the manufacturing process can be simplified.

  The six effects obtained by the above embodiment are summarized below.

  First, the lithography apparatus cost and the mask cost can be kept low. This is because the lithography apparatus necessary for the present invention does not need to be a state-of-the-art apparatus for resolving a fine pattern, and an old-type apparatus of several generations can be used. The price of the latest ArF excimer exposure apparatus is one digit more expensive than i-line two generations ago, as described in the item of the problem. As for masks, some of the latest ArF excimers can reach 10 million yen / mask, but for i-line two generations before, hundreds of thousands of yen / mask can be expected to reduce costs by 1 to 2 digits. . The effect of suppressing the price of the most expensive apparatus among the magnetic head processing apparatuses by one to two digits is very great.

  Second, the mask height and etching resistance during etching can be increased, and the process margin can be expanded. In general, a resist serving as a lithography mask has a thinner coating thickness at the tip corresponding to fine processing and a smaller margin for etching. The thickness of the most advanced ArF excimer resist is as thin as about 200 nm, compared to the i-line resist that can have a thickness of about 1 μm. At this level, the resist may disappear during the etching of the film to be processed, which is a strong restriction on the etching conditions. In particular, ion milling used in magnetic head processing has a low resist selectivity due to physical processing, and securing etching resistance tends to be a problem. Since the side wall mask of the present invention can set the mask height regardless of the resolution in principle, a sufficient etching margin can be secured. As a result, a high process margin increases processing stability and improves yield.

  The third point is that the variation in processing dimensions can be reduced. In recent years, the side wall roughness of the resist has become a problem with the miniaturization of processing dimensions. FIG. 4 shows an image of resist sidewall roughness. The accuracy of the pattern dimensions deteriorates due to variations in resist sidewall roughness and resist width itself. Resist width and roughness are difficult to suppress due to sensitivity variations during exposure and molecular variations due to the resist being made of a polymer material. Roughness with an amplitude of about several nanometers or more exists on the side wall of the current ArF resist. On the other hand, when the method of the present invention is used, the pattern dimensional accuracy is determined by the deposited film thickness of the sidewall mask material. In general, since the film formation variation is smaller than the resist roughness, the method of the present invention can suppress roughness and dimensional variation. Regarding the effect of suppressing the dimensional variation when using the sidewall mask method, IEEE Transactions on Electron Devices, Vol. 49, No. 3, March 2002 also shows the proof results.

  Fourth, by using lift-off, it is possible to realize an ideal shape that is close to the upper magnetic shield in the vicinity of the magnetoresistive film, shortening the effective gap length between shields and improving the resolution in this direction. There is an effect to.

  As a fifth point, by introducing a release layer and combining a sidewall mask and lift-off, an effect of improving lift-off property can be obtained even for a fine pattern. In order to ensure that the pattern is lifted off, the resist and release layer must remain at a certain thickness after ion milling. However, since the resist film thickness is smaller in lithography with fine patterns, the thickness of the resist is reduced by ion milling. This is an effective countermeasure against the occurrence of lift-off defects. This is particularly effective in a head such as a differential read magnetic head having a thick magnetoresistive film and a narrow track width. Until now, these thick-film and narrow-track sensors could not be lifted off by the usual method, so although it was known that the structure was effective in principle, it was difficult to put it into practical use in consideration of mass productivity. The method proposed here has the effect of realizing this.

  Sixth, by introducing an etching stopper under the side wall mask, it is possible to improve the dimensional stability against over-etching of the side wall mask, and to prevent etching damage and film loss to the sensor film when forming the side wall mask. . This prevents the asymmetry of the track shape, improves the shape stability, and stabilizes the characteristics.

  Although the embodiment of the present invention has been described above, the effect of the present invention is not limited to the above case, and has the characteristic that a fine pattern exceeding the resolution limit of photolithography can be processed in the magnetic head manufacturing process. The present invention can also be applied to similar manufacturing methods.

  The present invention can be applied to the manufacturing industry of a high-resolution magnetic sensor using a magnetoresistive element, especially a reproducing magnetic head for a magnetic disk.

The schematic diagram which shows 1 process of a 5th Example. Schematic diagram of a recording / reproducing separation type head. The enlarged view of a reproducing head part. Explanatory drawing which shows resist side wall roughness typically. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows the structure of a magnetoresistive effect film | membrane. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows 1 process of a 1st Example. The schematic diagram which shows 1 process of a 1st Example. FIG. 17 is a bird's-eye view corresponding to FIG. 16. The schematic diagram which shows 1 process of a 2nd Example. The schematic diagram which shows 1 process of a 2nd Example. The schematic diagram which shows 1 process of a 3rd Example. Explanatory drawing of the reattachment of a side wall of a sidewall. The schematic diagram which shows 1 process of a 4th Example. The schematic diagram which shows 1 process of a 4th Example. The schematic diagram which shows 1 process of a 4th Example. The schematic diagram which shows 1 process of a 4th Example. The schematic diagram which shows 1 process of a 4th Example. The schematic diagram which shows 1 process of a 4th Example. The schematic diagram which shows 1 process of a 4th Example. The schematic diagram which shows 1 process of a 4th Example. The schematic diagram which shows 1 process of a 4th Example. The schematic diagram which shows 1 process of a 4th Example. The bird's-eye view corresponding to FIG. FIG. 3 is a schematic diagram showing the structure of a differential read magnetic head. The schematic diagram which shows 1 process of a 5th Example. The schematic diagram which shows 1 process of a 5th Example. The schematic diagram which shows 1 process of a 6th Example. The schematic diagram which shows 1 process of a 6th Example. The schematic diagram which shows 1 process of a 6th Example. The schematic diagram which shows 1 process of a 6th Example. The schematic diagram which shows 1 process of a 7th Example. The schematic diagram which shows 1 process of a 7th Example. The schematic diagram which shows 1 process of a 7th Example. The schematic diagram which shows 1 process of a 7th Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Recording head part, 2 ... Reproducing head part, 3 ... Lower magnetic shield, 4 ... Upper magnetic shield, 5 ... Magnetoresistive element, 6 ... Permanent magnet film, 7 ... Photoresist, 8 ... Element height pattern, 9 ... Alumina insulating film, 11 ... alumina film, 12 ... track width, 13 ... gap length, 14 ... resist sidewall roughness, 15 ... permalloy film, 16 ... magnetoresistance effect film, 17 ... underlayer, 18 ... antiferromagnetic layer, 19 ... pinned layer, 20 ... intermediate layer, 21 ... free layer, 22 ... cap layer, 23 ... etch stopper layer, 24 ... peeling layer, 25 ... dummy pattern, 26 ... sidewall alumina film, 27 ... sidewall, 28 ... side Wall mask, 29... Unnecessary portion of magnetoresistive effect film, 30... Side wall trace, 31... Strong side wall film, 32. Alumina, 35 ... sensor height zero position of the track, 36 ... diamond-like carbon film

Claims (15)

In a method of manufacturing a magnetic head, comprising: a magnetoresistive film; a separation part that is provided adjacent to the magnetoresistive film and does not exhibit a magnetoresistive effect; and an electrode part that is electrically connected to the magnetoresistive film.
Forming a magnetoresistive film;
Forming an etch stopper layer on the magnetoresistive film;
Forming a dummy pattern on the etch stopper layer;
Depositing a film for forming a sidewall on the surface including the sidewall of the dummy pattern;
Etching back the sidewall forming film to form a sidewall mask on the sidewall of the dummy pattern;
Removing the dummy pattern;
Processing the track width of the magnetoresistive film using the sidewall mask;
A method of manufacturing a magnetic head, comprising:   2. The method of manufacturing a magnetic head according to claim 1, wherein the sidewall forming film is deposited by sputtering.   2. The method of manufacturing a magnetic head according to claim 1, wherein the sidewall forming film is deposited using an atomic layer deposition method.   2. The method of manufacturing a magnetic head according to claim 1, wherein the sidewall forming film is made of an alumina film.   2. The method of manufacturing a magnetic head according to claim 1, wherein the etch stopper layer is made of a diamond-like carbon film. In a method of manufacturing a magnetic head, comprising: a magnetoresistive film; a separation part that is provided adjacent to the magnetoresistive film and does not exhibit a magnetoresistive effect; and an electrode part that is electrically connected to the magnetoresistive film.
Forming a magnetoresistive film;
Forming a release layer on the magnetoresistive film;
Forming a dummy pattern on the release layer;
Depositing a film for forming a sidewall on the surface including the sidewall of the dummy pattern;
Etching back the sidewall forming film to form a sidewall mask on the sidewall of the dummy pattern;
Removing the dummy pattern;
Processing the track width of the magnetoresistive film using the sidewall mask;
Removing unnecessary portions on the magnetoresistive film by lift-off using the release layer;
A method of manufacturing a magnetic head, comprising:   7. The method of manufacturing a magnetic head according to claim 6, wherein the release layer is made of polyimide.   7. The method of manufacturing a magnetic head according to claim 6, wherein the lift-off is a CMP lift-off that uses CMP to remove a deposited portion on the magnetoresistive film. In a method of manufacturing a magnetic head, comprising: a magnetoresistive film; a separation part that is provided adjacent to the magnetoresistive film and does not exhibit a magnetoresistive effect; and an electrode part that is electrically connected to the magnetoresistive film.
Forming a magnetoresistive film;
Forming a release layer and an etch stopper layer on the magnetoresistive film;
Forming a dummy pattern on the release layer and the etch stopper layer;
Depositing a film for forming a sidewall on the surface including the sidewall of the dummy pattern;
Etching back the sidewall forming film to form a sidewall mask on the sidewall of the dummy pattern;
Removing the dummy pattern;
Processing the track width of the magnetoresistive film using the sidewall mask;
Removing unnecessary portions on the magnetoresistive film by lift-off using the release layer;
A method of manufacturing a magnetic head, comprising:   10. The method of manufacturing a magnetic head according to claim 9, wherein the sidewall forming film is deposited by sputtering.   10. The method of manufacturing a magnetic head according to claim 9, wherein the sidewall forming film is deposited using an atomic layer deposition method.   10. The method of manufacturing a magnetic head according to claim 9, wherein the sidewall forming film is made of an alumina film.   10. The method of manufacturing a magnetic head according to claim 9, wherein the etch stopper layer is made of a diamond-like carbon film.   10. The method of manufacturing a magnetic head according to claim 9, wherein the release layer is made of polyimide.   10. The method of manufacturing a magnetic head according to claim 9, wherein the lift-off is a CMP lift-off.

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