METHOD OF MANUFACTURING A MAGNETIC HEAD HAVING A THIN, WEAR-RESISTANT LAYER, AND MAGNETIC HEAD OBTAINABLE BY SAID METHOD

Abstract: Method of manufacturing a magnetic head having a head face (5) and a layer structure with a transducing element (E) and a flux-guiding element (19a) terminating in the head face. The head face is provided with a wear-resistant layer (31) having a maximum thickness of 60 nm for forming a contact face (33). To improve the wear resistance, a bundle of ions is directed onto the wear-resistant layer, while ions are implanted in the wear-resistant layer until an implantation dose of between 10<10> ions/cm<2> and 10<14> ions/cm<2> is reached.

Description: Method of manufacturing a magnetic head having a thin, wear-resistant layer, and magnetic head obtainable by said method. The invention relates to a method of manufacturing a magnetic head having a head face and a layer structure with a tr.ansducing element and a flux-guiding element terminating in the head face, the head face being provided with a non-magnetic layer for forming a contact face. The invention also relates to a magnetic head provided with a head face and a layer structure with a transducing element and a flux-guiding element terminating in the head face, the head face being provided with a non-magnetic layer forming a contact face. Such a method and a magnetic head obtained by the known method are known from DE-A 43 23 115 (PHN 14.151). The known magnetic head is a thin-film magnetic head and comprises a substrate of, for example an NiFe ferrite on which a layer structure is provided. The layer structure, which is composed of magnetic layers, electric layers and insulation layers during manufacture of the magnetic head, is protected by a protective block of a non-magnetic material. The known magnetic head has a head face in which one or more transducing gaps terminate and to which one or more flux-guiding elements are adjacent. During manufacture of the magnetic head, the head face is formed by processing, for example grinding or polishing a side face of an intermediate product comprising the substrate, the layer structure and the protective element. In a subsequent manufacturing step, the head face is provided with a wear-resistant layer, for example by means of sputtering. The wear-resistant layer of the known magnetic head is a Cr 2 O 3 layer or a multilayer composed of a Cr layer and a Cr 2 O 3 layer. In the latter case, the Cr layer is present between the head face and the Cr 2 O 3 layer, with the Cr layer mainly serving to improve the adhesion of the wear-resistant layer to the head face. The wear-resistant layer of the known magnetic head has a thickness of 100 nm maximum and forms a contact face for a recording medium moving relative to the magnetic head, such as a magnetic tape. In magnetic heads which are built up in layers, relatively soft materials are used, notably the soft-magnetic materials of flux-guiding elements in addition to relatively hard materials, notably substrate materials, for example Al 2 O 3 /TiC. By abrasive action of a recording medium moving along a head face which is not provided with a wear- resistant layer, the relatively soft materials on the head face may wear considerably, which results in a hollowing of the layer structure on the head face. Such a hollowing increases the distance between the recording medium and the soft-magnetic materials and hence reduces the teansmission of information between the recording medium and the magnetic head. To inhibit hollowing, the magnetic head known from DE-A 43 23 115 is provided with a wear- resistant layer. The Cr 2 O 3 layer used in the known magnetic head provides a reasonable resistance to wear and corrosion. However, the presence of a layer on the head face implies a given distance between the recording medium and the head face during operation. This may have the drawback that signal losses occur during writing and/or reading information into and from the recording medium. In given applications, such as in data recording, only small signal losses are admissible and a relatively thick, wear-resistant layer is less suitable. It is an object of the invention to provide a method of the type described in the opening paragraph, with which a magnetic head provided with an eminently wear- resistant thin layer can be obtained. The method according to the invention is characterized in that a wear- resistant layer having a maximum thickness of 60 nm is formed as a non-magnetic layer, whereafter a bundle of ions moving towards said layer is directed onto the wear-resistant layer, while ions are implanted in the wear-resistant layer until an implantation dose of between 10 10 ions/cm 2 and IO 14 ions/cm 2 is reached. A layer comprising mainly Cr 2 O 3 , tetragonal or cubic stabilized ZrO 2 , HfO 2 , CN X in which 0.25 ≤ x < 1.5, or WC y in which 0.5 ≤ y < 1.5 is preferably formed as a wear-resistant layer on the contact face. After implantation, these materials yield layers having an eminent wear resistance. Said zirconium oxide is preferably doped with yttrium, cerium, calcium or titanium. Said materials are preferably provided by means of sputtering because the temperature remains relatively low in this deposition method. When a Cr 2 O 3 layer is formed, a chromium target is preferably used for sputtering, with the addition of oxygen. Such a process can easily be used in a production environment. Sputtering, for example RF sputtering in a space filled with a rare gas such as argon may be carried out without heating the magnetic head and without a bias field. To improve the adhesion to Cr 2 O 3 on the head face comprising various materials, it may be desirable to form a thin layer of mainly Cr on the head face prior to the formation of the layer mainly comprising Cr 2 O 3 . Both layers may be formed in the same sputtering device, while oxygen is not added during sputtering until after the layer mainly comprising Cr is formed. It has been found that the latter layer does not need to be thicker than 10 ran. When the method according to the invention is used, such an implantation energy is chosen that the head face lies just within, on or just outside the range of the ions to be implanted. Implantation energy is herein understood to mean the energy of the ions to be implanted immediately before they reach the wear-resistant layer. The value of the implantation energy is dependent on a number of factors such as the thickness and composition of the layer and the mass of the ions to be implanted. Rare gas ions such as argon, helium and neon have been found to be very suitable as implantation ions because these ions are chemically inert and therefore do not chemically modify the wear-resistant layer. Moreover, it has been found to be fairly simple to form suitable bundles of such ions, for which known ion implantation devices can be used. It has been found by experiment that the wear resistance of the wear- resistant layer improves at an implantation dose of between 10 10 ions/cm 2 and IO 14 ions/cm 2 . At such a dose, which can be obtained in a simple manner and within a short time, the material of the wear-resistant layer has undergone a suitable perturbation which is such that the layer has a greater resistance to wear as is caused, for example by an information medium moving along the wear-resistant layer. At a lower dose than that mentioned above, the perturbation provided is too small to effectively enhance the wear resistance. At a higher dose, the material of the wear-resistant layer appears to be damaged in such a way that the layer becomes more sensitive to wear. The improved wear resistance obtained by the measures according to the invention provides the possibility of using thin or very thin layers on the head face. It has also been found that an additional effect of ion implantation is that an improved adhesion of the wear-resistant layer to the head face can be realised as a result of occurring small changes on the interface between the wear-resistant layer and the head face. An embodiment of the method according to the invention is characterized in that ions are implanted at an implantation energy of at least 10 keV and at most 200 keV. As the wear-resistant layer is thinner, the required energy is lower. This means that an implantation energy of 10 keV minimum is required at a layer thickness of 10 nm, while more energy, increasing to 200 keV is required for thicker layers. Energy values outside the range between 10 keV and 200 keV are less suitable. It is another object of the invention to provide a magnetic head which is obtainable by the method according to the invention. The magnetic head according to the invention is characterized in that the non-magnetic layer is a wear-resistant layer having a thickness of 10 nm minimum and 60 nm maximum, which layer is provided with implanted ions in a dose of between 10 10 ions/cm 2 and IO 14 ions/cm 2 . An advantage of the magnetic head according to the invention is particularly the combination of the small layer thickness and the eminent wear resistance of the wear-resistant layer. On the one hand, a signal loss due to the presence of the wear- resistant layer is thereby minimized, and on the other hand a long lifetime of the layer is ensured. It is to be noted that implantation doses can be determined by means of known measuring methods such as Rutherford backscattering spectrometry (RBS) or secondary ion mass spectroscopy (SIMS). The non-magnetic wear-resistant layer preferably comprises mainly one of the materials Cr 2 O 3 , doped ZrO 2 , HfO 2 , CN X in which 0.25 ≤ x ≤ 1.5 and WC y in which 0.5 ≤ y ≤ 1.5 in which rare gas ions are implanted. When Cr 2 O 3 is used, a layer of mainly Cr is preferably present between the layer of mainly Cr 2 O 3 and the head face. It is to be noted that a magnetic head without a wear-resistant coating is known from JP-A 3-93017 in which ions are implanted in gliding faces of magnetic poles so as to improve the corrosion resistance of the soft-magnetic material of which said poles are manufactured. In contrast to this known magnetic head, the magnetic head according to the invention is provided with a contact face formed by a wear-resistant layer while ions for improving the wear resistance are implanted in non-magnetic material. It is also to be noted that it is known from JP-A-4-17116 to provide a magnetic medium such as a disc or tape with a protective layer against corrosion. The protective layer is obtained by directing N, He, Ne, Ar, Au or Ti ions onto a carbon layer or an SiO 2 layer for such a long time that a quantity of between 5.10 16 ions/cm 2 and 1.10 17 ions/cm 2 is obtained. The required energy is between 100 keV and 500 keV. The above- mentioned known quantity is unsuitable for achieving the afore-described objects of the invention. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. In the drawings: Fig. 1 is a diagrammatic cross-section of a transducing gap in an embodiment of the magnetic head according to the invention, Fig. 2 is a perspective elevational view of the magnetic head shown in Fig. 1, Fig. 3 is a perspective elevational view of the magnetic head in a first production phase, in which the magnetic head is not yet provided with a wear-resistant layer, and Fig. 4 is a perspective elevational view of the magnetic head in a second production phase in which ions are implanted. The thin-film magnetic head according to the invention, shown in Figs. 1 and 2, comprises a substrate 1, in this example of a magnetic material such as Al 2 O 3 /TiC on which a layer structure 2 composed of magnetic layers, electric layers and insulation layers is provided. The layer structure 2 is protected by a counter block 3 of a non-magnetic material, for example Al 2 O 3 /TiC. The magnetic head has a head face 5 in which eleven transducing gaps terminate. A group of nine gaps SI of the eleven transducing gaps is intended for reading information in a digital form, and a group of two gaps Sll is intended for reading information in an analog form from a record carrier 7 which moves in a direction x along the magnetic head. The gaps SI for digital use generally have a smaller gap length than the gaps Sll for analog use. Alternatively, such a gap length can be chosen that both analog and digital information can be read by one and the same gap. The magnetic head may of course also be provided with a larger or smaller number than said eleven gaps, or even with one transducing gap. The magnetic head according to the invention has an insulation layer 9 provided on the substrate 1, while in this embodiment electric conductors C which may extend up to the transducing gaps, are provided on this insulation layer. The magnetic head further comprises eleven magnetoresistive elements E further referred to as MR elements which comprise, for example an NiFe layer on which one or more equipotential strips of, for example Au may be provided. Each MR element E is provided with a pair of connection tracks which terminate in connection faces. It is to be noted that an MR element provided with equipotential strips is known per se and is described, inter alia, in US-A 4,052,748. Said electric conductors C are used for driving the MR elements E and are each provided with connection tracks terminating in connection faces. The magnetic head shown also comprises eleven pairs of flux guides of a soft-magnetic material, for example NiFe or AlFeSi, each pair having a first or front flux guide 19a and, spaced apart therefrom, a second or rear flux guide 19b. Each front flux guide 19a extends as far as the head face 5 for cooperation with the magnetic record carrier 7. Of the MR elements E which in this embodiment are present between the substrate 1 and the flux guides, each MR element constitutes a bridge between a first and a second flux guide 19a and 19b. In given constructions and for given uses, it is possible to omit the rear flux guides. It is also possible to start from a non-magnetic substrate and to provide an extra flux guide. Moreover, the magnetic head may of course comprise a smaller or larger number than the number of said MR elements and/or said pairs of flux guides. The electric conductors, the MR elements and the flux guides are electrically insulated with respect to each other by a plurality of insulation layers of an electrically and magnetically insulating material, for example an oxide or polymer. The insulation layers are denoted by the reference numerals 21 and 23 in Fig. 1. A further insulation layer 25, for example in the form of an adhesive layer is provided between the flux guides 19a and 19b on the one hand and d e counter block 3 on the other hand. The head face 5 is provided with a wear-resistant layer 31 which forms a contact face 33 for cooperation with the tape-shaped record carrier 7. The wear-resistant layer 31 which is non-magnetic but electrically insulating has a thickness of 30 nm in this embodiment. The layer 31 particularly protects the layer structure 2 from wear. The layer 31 has of course also a favourable effect on the substrate 1 and the counter block 3. A method of forming the wear-resistant layer 31 on the head face will be described with reference to Figs. 3 and 4. After the assembly of substrate 1, layer structure 2 .and counter block 3 has been provided with the head face 5, for example by grinding and/or polishing, the assembly is placed in a known sputtering device containing a chromium target. By means of sputtering, a thin, mainly Cr-containing layer is formed on the head face 5, which layer is approximately 5 nm thick. Subsequently, mainly Cr 2 O 3 for forming a layer 31a mainly comprising Cr 2 O 3 is formed on the formed layer of Cr by means of reactive RF sputtering, for example RF diode sputtering at 10 mTorr Ar and 1 mTorr O 2 . The intermediate product obtained is subsequently placed in a known ion implantation device whereafter a bundle of argon ions 35 is directed onto the layer 31a, at which argon ions are implanted in the layer 31a for forming the wear-resistant layer 31. In this example, the implantation energy is approximately 50 keV and is chosen to be such that areas just before, on or just behind the head face 5 are located within the range of argon ions. Implantation is continued until an implantation dose of approximately 10 13 ions/cm 2 is reached. A given perturbation in the layer 31a is caused by implantation, which perturbation is of such a nature that it impedes extensions of beginning cracks (dislocations) in the layer. Moreover, mixing effects on the head face may yield an improvement of the adhesion of the wear- resistant layer 31 to the head face, which contributes to the wear resistance of the layer 31. It is to be noted that the invention is not limited to the embodiments shown. For example, the magnetic head according to the invention may comprise one or more inductive elements instead of or in addition to MR elements. Although this is less attractive, it is also possible to sputter with a Cr 2 O 3 target for forming a layer mainly comprising Cr 2 O 3 in the method according to the invention. It is of course within the scope of the invention to form the wear-resistant layer mainly from one of the materials ZrO 2 (stabilized), HfO 2 , CN X in which 0.25 ≤ x ≤ 1.5 and WC y in which 0.5 ≤ y ≤ 1.5 instead of a layer mainly comprising Cr 2 O 3 . The values for the thickness of the wear-resistant layer, the implantation dose and the implantation energy given elsewhere in this document should then of course be taken into account.

Claims: CLAIMS: 1. A method of manufacturing a magnetic head having a head face and a layer structure with a transducing element and a flux-guiding element terminating in the head face, the head face being provided with a non-magnetic layer for forming a contact face, characterized in that a wear-resistant layer having a maximum thickness of 60 nm is formed as a non-magnetic layer, whereafter a bundle of ions moving towards said layer is directed onto the wear-resistant layer, while ions are implanted in the wear-resistant layer until an implantation dose of between 10 10 ions/cm 2 and IO 14 ions/cm 2 is reached. 2. A method as claimed in Claim 1, characterized in that the wear-resistant layer is mainly formed from one of the materials Cr 2 O 3 , tetragonal or cubic stabilized ZrO 2 , HfO 2 , CN.. in which 0.25 ≤ x ≤ 1.5, and WC y in which 0.5 ≤ y ≤ 1.5. 3. A method as claimed in Claim 2, characterized in that the material is provided by means of sputtering. 4. A method as claimed in Claim 2 or 3, characterized in that Cr 2 O 3 is deposited after a layer mainly comprising Cr has been provided on the head face. 5. A method as claimed in Claim 1, 2, 3 or 4, characterized in that rare gas ions are implanted. 6. A method as claimed in Claim 1, 2, 3, 4 or 5, characterized in that ions are implanted at an implantation energy of at least 10 keV and at most 200 keV. 7. A magnetic head obtainable by the method as claimed in any one of the preceding Claims, which magnetic head has a head face and a layer structure with a transducing element and a flux-guiding element terminating in the head face, the head face being provided with a non-magnetic layer forming a contact face, characterized in that the non-magnetic layer is a wear-resistant layer having a thickness of 10 nm minimum and 60 nm maximum, which layer is provided with implanted ions in a dose of between 10 10 ions/cm 2 and IO 14 ions/cm 2 . 8. A magnetic head as claimed in Claim 7, characterized in that the wear- resistant layer comprises mainly one of the materials Cr 2 O 3 , doped ZrO 2 , HfO 2 , CN X in which 0.25 ≤ x < 1.5, and WC y in which 0.5 ≤ y ≤ 1.5. 9. A magnetic head as claimed in Claim 7 or 8, characterized in that an adhesive layer of mainly Cr is present on the head face, which adhesive layer is provided with the wear-resistant layer of mainly Cr 2 O 3 . 10. A magnetic head as claimed in Claim 7, 8 or 9, characterized in that the implanted ions are rare gas ions.

Inventors: LASINSK PETER, OVERWIJK MARK HUBERT FREDERIK, THEUNISSEN GERARDUS STEPHANUS, LASINSK, PETER, OVERWIJK, MARK, HUBERT, FREDERIK, THEUNISSEN, GERARDUS, STEPHANUS, ANTONIUS, MARIA
Applicants: PHILIPS ELECTRONICS NV, PHILIPS NORDEN AB, PHILIPS ELECTRONICS N.V.
Application year: 1996
Main classification: G11B5
IPC codes: G11B5