EP1810283A2

EP1810283A2 - Recording and/or playback device comprising multiple magnetic heads with azimuth gaps

Info

Publication number: EP1810283A2
Application number: EP05819144A
Authority: EP
Inventors: Jean-Baptiste Albertini; Pierre Gaud
Original assignee: Commissariat a lEnergie Atomique CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2004-11-04
Filing date: 2005-11-02
Publication date: 2007-07-25
Also published as: WO2006048580A3; WO2006048580A2; FR2877484A1; US20080266709A1; JP2008519384A

Abstract

The invention relates to a recording and/or playback device of a magnetic recording medium (35) with magnetic tracks (36), comprising numerous magnetic heads (30.1 to 30.4) which each consist of a pair of pole pieces that are separated by a non-magnetic gap (e). According to the invention, the pairs of pole pieces are grouped together on at least one medium (1000) having a non-zero angle of inclination (?) of between ± 90° in relation to the tracks. Moreover, all of the gaps (e) in the pairs of pole pieces of the medium (1000) have the same azimuth angle (a) of between ± 90°, terminals excluded, in relation to an axis normal to the medium (1000).

Description

RECORDING AND / OR PLAYING DEVICE WITH MULTIPLE MAGNETIC HEADS WITH AZIMUTES

DESCRIPTION

TECHNICAL AREA

The subject of the present invention is a device for recording and / or reading with multiple magnetic heads with azimuth gaps as well as a method for producing such a device.

This device with multiple magnetic heads finds its application in the magnetic recording and / or reading of data on any recording medium that is magnetic or magneto-optical and more particularly on magnetic tape. Subsequently, the term magnetic medium has been used and this includes magnetic media and magneto-optical media. In the same way, when we speak of magnetic tracks it includes the tracks of a magnetic medium and those of a magneto-optical medium.

STATE OF THE PRIOR ART

Recall that the magnetic tape is the information carrier most suitable today for the compact storage of large amounts of information, typically of the order of a terabyte (1 terabyte = 63 ² bytes = 8 63 ² bits) and -of the. The end applications of tape storage are typically the archiving and backup of computer or more generally digital data. These data can be for example those of bases of data, digitized films, audio or computer files often from computers or digital devices such as camcorders, VCRs or servers. These data are often called "multimedia" and have an industrial, professional or consumer background.

Among the different types of recordings on magnetic media, we can mention:

the linear recording in which a fixed set of multiple magnetic heads writes and reads several magnetic tracks in parallel on a linearly moving magnetic tape,

the helical registration in which one or more pairs of magnetic heads, mounted on a cylindrical drum rotating at high speed, write and read magnetic tracks in the form of portions of helices on a magnetic tape slowly scrolling while winding and sliding around the drum,

- The magneto-optical recording in which a set of magnetic heads writes tracks on a support, the reading being provided by a laser beam detecting directly or indirectly, by Kerr or Faraday effect, the magnetization of previously written bits.

The invention can be applied to linear recording, helical recording or magneto-optical recording.

FIG. 1 gives a schematic representation of a recording and / or reading device of the prior art. A bar 1 of heads magnetic spacers 3 spaced apart by a pitch D is arranged along a generatrix of a fixed cylindrical support 2 (drum). Each magnetic head 3 comprises two pole pieces 3.1, 3.2 separated by a gap 3.3 non-magnetic. Subsequently, when we talk about the air gap of a pair of polar parts it is the air gap between two polar parts of a pair. The magnetic recording medium 4 to be read or recorded moves linearly close to the bar 1. This type of recorder has the advantage of being relatively simple mechanically (fixed or weakly moving magnetic heads) and allows, thanks to its multiple magnetic heads, high data rates.

However, it is not optimum in terms of recording density. The fact of having a pitch D between magnetic heads 3 relatively large in the standard configuration because of the bulk of the magnetic circuit and the recording means and / or reading requires:

on the one hand to have a "serpentine" recording, that is to say a large number of round trips to record the whole of the magnetic medium 4 with tracks 5 whose pitch T 'is smaller that step D,

- On the other hand, given the problems of tracking 5 and possible temperature differences, to have a space 6 between tracks 5 (said intergrator) important, resulting in a loss of space.

In addition, the tracks 5 recorded in a single pass being relatively long distance, the simultaneous reading of these relatively spaced tracks is penalized by the mechanical flexibility of the magnetic recording medium 4 which can cause read errors due to misalignment of the bits of these tracks.

US Pat. No. 5,452,165 discloses a device for recording and / or reading a magnetic medium with magnetic tracks. Several pairs of pole pieces are carried by the same support. Any two pairs of successive polar pieces have non-zero, equal and opposite azimuth angles, and between ± 90 ° excluded. The support has a given angle of inclination (non-zero and different from 90 °) with respect to the tracks. In addition, the widths of the tracks are not equal, so that the electrical signals recorded on successive tracks have different amplitudes. Reading errors may occur.

The method proposed in this patent, to achieve the azimuth angle does not allow a perfect definition and reproducibility of this angle, which will be achieved by the present invention.

Patent application FR-A-2 774 797 also discloses a recording and / or reading device with multiple azimuth magnetic heads. This device comprises several assembled supports on which are distributed magnetic heads. This device does not provide that the supports have an angle of inclination with respect to the tracks. It does not therefore make heads magnetic "massively parallel", the realization of magnetic heads to read or write n tracks requiring n supports assembled, which limits in practice n to 2, 3 or 4 for reasons of efficiency. The constraints during the assemblies lead to a weakening of the recording and / or reading device.

This device also does not provide magnetic heads cooperating with overlapping tracks, as is done today in industry, because the distance, normal to the supports between two pairs of pole pieces belonging to two consecutive supports is greater or equal to zero. This configuration does not allow the recording and / or playback device to adapt to various recording standards.

STATEMENT OF I / INVENTION

The object of the present invention is precisely to propose a recording and / or reading device with multiple magnetic heads which does not have the drawbacks mentioned above.

An object of the invention is to perform recordings and / or readings of the magnetic recording medium in a limited number of passes due to the high degree of parallelism of the multiple magnetic heads of the device.

Another object of the invention is to obtain a good accuracy of alignment of the magnetic heads with respect to the tracks to overcome the problems encountered during the reading as well as a good precision for industrial production in mass production of the azimuth angle and the width of the pole pieces which condition recording and reading on magnetic tracks of width and precise positioning.

Yet another object of the invention is to increase the recording densities by decreasing the widths of tracks and interpistes.

A further object of the invention is to facilitate track tracking of the magnetic recording medium.

The manufacturing method allows better control of the key parameters of the recording and / or reading device in mass production compared to existing methods.

It thus makes it possible in particular to increase the number of magnetic heads that can operate in parallel and to produce them at a competitive cost with good yields.

To achieve this, the present invention relates to a device for recording and / or reading a magnetic medium with magnetic tracks. It comprises several magnetic heads each comprising a pair of pole pieces separated by a nonmagnetic air gap. These pairs of pole pieces are grouped on at least one support having a non-zero angle of inclination, between ± 90 ° with respect to the tracks, all the air gaps of the pairs of pole pieces of the support having the same azimuth angle between ± 90 ° limits excluded in relation to a direction normal to the support. It is advantageous for the device to comprise at least two consecutive supports defining, when they are parallel, a polar inter-piece spacing between face planes facing polar parts situated on the two consecutive supports.

This polar inter-piece distance is such that P + d = (D + nT) .tg (θ) with θ angle of inclination of the supports relative to the tracks, T longitudinal pitch of the gaps of the pairs of polar pieces placed on a same support, D longitudinal shift relative to the supports between two pairs of consecutive pole pieces placed on two consecutive supports, P width of the pole pieces and n integer.

Magnetic shielding and / or magnetoresistive reading means may be placed between the two supports in a space corresponding to the inter-piece polar distance.

In a variant that allows the bits of the inscribed signals to be orthogonal to the tracks, the azimuth angle and the inclination angle are equal in module or in absolute value.

In another embodiment, the azimuth angle and the tilt angle are different, which makes it possible to record and / or read azimuth bits on the magnetic medium.

When the device comprises several supports, the latter can be superimposed. When it comprises at least two consecutive supports, they can have different angles of inclination.

The azimuth angles of the air gaps of the pair of pole pieces of one of the supports may then be different from the azimuth angles of the pairs of pole pieces of the other support.

Advantageously, two pairs of pole pieces belonging to different media, for example consecutive, cooperate with two consecutive magnetic tracks for reading or recording.

The device may comprise at least one block of at least one support for recording and at least one block of at least one support for reading, these blocks being arranged one after the other in the direction tracks.

Alternatively, the device may comprise at least one block of one or more media for recording and at least one block of one or more media for reading, the supports of these blocks being secured to each other.

Each track can be recorded and read respectively by a pair of pole pieces, the pair of pole pieces for recording and the pair of pole pieces for playback belonging to different media.

To avoid the risk of crosstalk, a block for reading can be separated from a block for recording by a shielding screen. The device comprises, for each magnetic head, a magnetic circuit incorporating a pair of pole pieces and possibly a magnetic flux guide, this magnetic circuit cooperating with recording and / or reading means. In this context, a magnetic flux guide may comprise several parts: the core of a solenoid winding, pads, a rear magnetic piece, a magnetoresistive sensor flux guide.

The recording and / or reading means may be inductive or magnetoresistive.

Signal processing means may cooperate with the recording and / or reading means.

The present invention also relates to a method for producing a recording and / or reading device on a magnetic strip recording magnetic medium which comprises the following steps: on at least one substrate forming several pairs of polar pieces of magnetic heads, these pole pieces being separated by a nonmagnetic air gap, the air gaps of these pairs of pole pieces all having the same azimuth angle, between ± 90 ° excluded terminals relative to a normal direction to the substrate; production of recording and / or reading means and possibly magnetic flux guides able to cooperate each with a pair of pole pieces; treatment of the substrate to give it a non-zero angle of inclination between ± 90 ° with respect to the magnetic tracks.

The recording and / or reading means and the possible magnetic flux guides may be made on at least one additional substrate which is assembled after positioning with the substrate carrying the pairs of pole pieces.

As a variant, the recording and / or reading means and the possible magnetic flux guides may be made on the substrate carrying the pairs of pole pieces.

The treatment may consist in performing a grinding of the substrate (s).

Alternatively, the treatment may consist of mounting one or more parts of the substrate or substrates or substrates in the same mechanical support.

When there are several substrates carrying pairs of pole pieces, these substrates are assembled after alignment.

It may be provided to insert a layer of electrically insulating material or shims between two consecutive substrates carrying pairs of pole pieces, this layer may optionally comprise magnetoresistive reading means and / or a magnetic shielding screen.

The method may consist of producing, on a substrate, pairs of magnetic connection pads for magnetically connecting each a flow guide or a recording means and / or reading to a pair of pole pieces carried by an identical or different substrate.

The assembly of two of the substrates is preferably done after turning one of them to face the faces worked.

A step of thinning at least one of the substrates may be provided before and / or after assembly.

The substrates may have different angles of inclination, in which case the azimuth angle of the air gaps of pairs of polar pieces of a substrate is different from the azimuth angle of the air gaps of pairs of polar pieces of a other substrate.

A pair of pole pieces can be made by anisotropically etching a first box in the substrate, forming a non-magnetic layer on the substrate, by filling the first box with magnetic material, by isotropically etching a second box that is adjacent to the first box. box, filling the second box with magnetic material.

When there are several substrates carrying pairs of pole pieces, to achieve the pairs of magnetic studs, it is possible by isotropic etching, pairs of boxes in the substrate to accommodate the pairs of magnetic studs and fill the pairs of boxes. magnetic material.

Surface planarization can be carried out after any one of the magnetic material filling steps. The substrate carrying pairs of pole pieces may be formed of electrically insulating material located between two layers, one of which carrying the boxes is monocrystalline, the other optionally being removed partially or completely later.

Alternatively the substrate carrying pairs of pole pieces may be formed of an electrically insulating material located between a layer of wear resistant material and a layer of monocrystalline material comprising the boxes.

The assembly can be done by gluing, by molecular assembly, by anodic assembly or by fusible beads.

The additional substrate within which the recording and / or reading means and the possible magnetic flux guides may be, may optionally be multilayered with a layer of electrically insulating material.

In a variant, the additional substrate within which the recording and / or reading means and the possible magnetic flux guides may comprise may include a layer of wear resistant material possibly covered with electrically insulating material.

In addition, the method comprises a step of producing signal processing means (for example preamplifiers, multiplexers, demultiplexers) which cooperate with the recording and / or reading means. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood on reading the description of exemplary embodiments, given purely by way of indication and in no way limiting, with reference to the appended drawings in which:

- Figure 1 (already described) shows a recording device and / or linear reading of the prior art;

FIG. 2 shows an example of a recording and / or reading device according to the invention;

FIGS. 3A, 3B, 3C show three other examples of a recording and / or reading device according to the invention;

FIG. 4 shows another example of a recording and / or read device according to the invention in which the pairs of pole pieces are distributed on either side of an insulating layer of a support;

FIGS. 5A, 5B show in three dimensions a recording and / or reading device of the prior art and a recording and / or reading device according to the invention;

FIGS. 6A to 6E show steps for producing pairs of pole pieces and rear closing parts of the magnetic circuit of a recording and / or read device according to the invention; FIGS. 7A to 7E show steps for producing the rest of the magnetic circuit and means for recording and / or reading a recording and / or reading device according to the invention;

- Figures 8A, 8B show assembly and finishing steps of the structures of Figures 6D and 7E;

FIG. 9 illustrates the grouping on the same mechanical support of two groups of magnetic heads, these groups of magnetic heads having the same angle of inclination with respect to the tracks of the magnetic recording medium;

FIG. 10 shows a recording and / or reading device according to the invention comprising recording heads and read heads placed alternately;

FIGS. HA to HD show steps for producing pairs of pole pieces of the recording heads of FIG. 10;

FIGS. 12A to 12D show steps for making the pairs of pole pieces of the read heads of FIG. 10 as well as the assembly and finishing of these pairs of pole pieces to those illustrated in FIG.

FIGS. 13A and 13B show steps for producing the magnetic circuit and means for recording and / or reading a recording and / or reading device according to the invention; FIGS. 14A and 14B show assembly and finishing steps of the structure of FIG. 12D to that of FIG. 13B, FIG. 14C showing another variant of a reading device according to the invention;

- Figure 15 shows yet another variant of a device according to the invention.

Identical, similar or equivalent parts of the different figures described below bear the same numerical references so as to facilitate the passage from one figure to another.

The different parts shown in the figures are not necessarily in a uniform scale, to make the figures more readable.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

An example of a recording and / or reading device according to the invention will now be described with reference to FIG. 2.

This device is intended for recording and / or reading information on tracks 36 carried by a magnetic recording medium 35. This magnetic recording medium 35 is represented as a band but other forms would be possible, for example a disk.

It will be recalled that a magnetic head conventionally comprises a magnetic magnetic flux closing circuit terminating on a pair of polar parts separated by a non-magnetic gap. This Magnetic circuit may include in addition to pairs of pole pieces a magnetic flux guide. In some configurations, the magnetic flux guide is absent and the pairs of pole pieces have a shape suitable for this magnetic flux guide function.

Recording and / or reading means cooperate with the magnetic circuit, it may be at least one coil which surrounds the magnetic circuit for the inductive recording and / or reading heads or at least one a magnetoresistance for the magnetic reading heads. This magnetoresistance can be inserted into the magnetic circuit at an air gap thereof. It can advantageously take the form of a rod made of giant magnetoresistance material GMR (abbreviation Anglo-Saxon Giant Magneto Resistance) or magnetoresistance tunnel TMR effect. In the absence of flux guide, the magnetoresistance cooperates with a pair of pole pieces.

The device according to the invention comprises several magnetic heads 30.1 to 30.4 which are each represented in FIG. 2 by a pair of pole pieces separated by a non-magnetic air gap. The device also comprises at least one support 1000 and the pairs of pole pieces of the magnetic heads 30.1 to 30.4 are distributed one after the other while being aligned on this support 1000. In an example described later in FIG. two supports 1000, 1001 are shown which are assembled to one another. We can of course consider using more than two brackets assembled after precise positioning.

The support 1000 is substantially plane, the pairs of pole pieces 30.1 to 30.4 of the magnetic heads rest on a main surface of the support which is substantially flat.

When the device according to the invention comprises at least two parallel supports 1000, 1001 as in FIG. 4, at least one inter-support layer 33 is provided making it possible to separate the levels of pairs of pole pieces by a well-adjusted distance d. This distance d is counted between face planes facing polar pieces on two consecutive supports. This inter-support layer 33 may advantageously comprise a magnetic shielding to avoid problems of cross-talk between magnetic heads located on different supports. It may also include magnetoresistive reading means.

The magnetic heads (or pairs of pole pieces) are azimuthed, and on the same support, all pairs of pole pieces have an air gap e which has the same azimuth angle α between ± 90 ° excluded terminals compared to a normal direction to support 1000.

An azimuth angle α zero is perpendicular to the main face of the support 1000 and an azimuth angle α equal to ± 90 ° would be parallel to the main face of the support 1000. Typically the azimuth angle α is less than or equal to at ± 45 °. For each pair of pole pieces, a magnetic flux guide and / or a magnetoresistive element (not visible in FIG. 2 but visible in FIG. 10) may rest on a main face of a support 1000, possibly in an insulating layer 33 near the pair of polar parts concerned. In the recording and / or reading device of the invention, the functional faces of the pole pieces are the faces perpendicular to the main faces of the initial supports which come into contact with the magnetic recording medium, and which will appear after cutting chips (or blocks) in the support.

Each magnetic head is intended to cooperate with the magnetic recording medium 35 oriented substantially parallel to the functional faces of the pole pieces and therefore substantially perpendicular to the main face of the support 1000.

This magnetic medium 35 comprises numerous parallel magnetic recording tracks 36 on which the magnetic heads 30.1 to 30.4 are intended to write or read information in the form of a succession of bits. These tracks 36 have a general direction x and have an angle of inclination θ with respect to the main surface of the support 1000 (or with respect to the length of the magnetic heads 30.1 to 30.4). In other words, the support 1000 has the angle of inclination θ with respect to the tracks 36. This inclination angle θ is non-zero and lies between ± 90 °. When the recording and / or reading device comprises several supports 1000, 1001 assembled, these can have the same angle of inclination θ with respect to the general direction x of the magnetic recording tracks 36. This angle of inclination θ can be obtained for example by means of a suitable mechanical machining of the support 1000.

However, it is possible to provide, as in FIG. 3C, an assembly of several supports, among which at least two consecutive supports have different angles of inclination θ1, Θ2.

The tracks 36 may not be joined and be separated by an interpiste 37.

Generally speaking, let P denote the width of the pairs of pole pieces 30.1 to 30.4 on the support 1000 and the longitudinal pitch of the gaps of the pairs of polar pieces on the support 1000. Let L be the width of a track 36 and i the width of an interpiste 37 (counted perpendicular to the x direction).

The angle of inclination θ is expressed by: sin (θ) = (L + i) / (T)

The width of the tracks registered is given by:

L = P.cos (α -θ) / cos (α)

Here is now a realistic digital application. If T = 200 μm, L = 5 μm and i = 0, 1 μm (smallest interpist possible), we deduce: sin (θ) = (L + i) / (T) = 5.1 / 200 = 0.0255, hence θ≈l, 5 °. It is possible, as in FIG. 2, for the azimuth angle α to have a value different from that of the angle of inclination θ. The recorded bits will have an angle α-θ with the general direction x of the recorded track. As a variant, it is possible, as shown in FIGS. 3A and 3B, for the azimuth angle α and the inclination angle θ to be equal to α = θ. In this case the bits will be written perpendicular to the general direction of the tracks. This variant corresponds to the current registration standard.

We then obtain:

L = P.cos (α - θ) / cos (α) = P / cos (α), or else

P = L.cos (α)

By taking the values of the previous digital application P ≈ 5 μm is obtained if α = θ and α ≈ 1 S °

We will see later a method of manufacturing such a recording device and / or reading which provides an azimuth angle α as small.

When it is desired to make a recording and / or reading device, it is preferable for reasons of performance to separate the magnetic heads dedicated to the recording from those dedicated to reading. The magnetic heads dedicated to the reading are preferably magneto-resistor type MR, giant magnetoresistance GMR or magnetoresistance TMR tunnel while the magnetic write heads are preferably inductive magnetic heads. Referring to Figures 3A, 3B, 3C.

The recording and / or reading device may comprise one or more first blocks B1 of at least one support 45 comprising recording heads (materialized by their pairs of pole pieces 40w and their gap e) and one or more seconds B2 blocks of at least one support 46 comprising reading heads (represented by their pairs of pole pieces 4Or and their gap e), these first and second blocks B1, B2 being placed one after the other in the general direction x of the tracks 47 of the magnetic recording medium 44. The interpistes are referenced 41.

In FIG. 3A, there is only one first block Bl dedicated to writing (the recording) and it is followed by a single second block B2 dedicated to reading. Each of the first and second blocks B1, B2 has as many write heads 4Ow 4Or read that are aligned with each other to cooperate.

In FIG. 3B, the recording and / or reading device comprises several (two in the example) first blocks B 1 which follow each other in the general direction of the tracks 47 and which are dedicated to writing and several (two in the example) second blocks B2 which follow in the general direction of the tracks 47 and which are dedicated to reading. The set of first blocks B1, like the set of second blocks B2, comprises as many write heads 4Ow (respectively as many read heads 4Or) as the magnetic medium 44 comprises tracks 47 which will be written in a single past. This The last configuration allows to increase the recording density by reducing the width of the tracks as well as that of the interpistes without necessarily removing the latter.

FIG. 3C shows a similar recording and / or reading device capable of writing and reading "double azimuth" tracks 47, that is to say that the azimuth angle of the bits written on the odd tracks starting from the high is αl-θl and that of the bits written on the even tracks is α2- Θ2. This type of device makes it possible to maximize the recording density by allowing a non-zero interphase without crosstalk on reading.

In the recording block Bl which has two supports 45, one of the supports 45 has an inclination angle θ1 and the other Θ2 which can be different from θ1. The gap of pairs of pole pieces 40w of one of the supports has an azimuth angle αl and the air gap of the pole pieces 40w of the other support has an azimuth angle α2. In the same way, in the reading block B2 which also has two supports 46, one of the supports 46 has the inclination angle θ1 and the other Θ2 so that the heads of the block B2 can read the information written by the heads of the block B1. The pair of polar pieces 4Or of one of the supports at the azimuth angle α1 and the air gap of the pole pieces 4Ow of the other support at the azimuth angle α2. The two supports of each block are assembled for example by means of wedges 49 which make it easy to adjust the angles of inclination of each of the supports. To avoid cross-talk between the blocks dedicated to different functions, a magnetic shielding screen 48 may be placed between the first blocks Bl and the second blocks B2.

Suitable means known to those skilled in the art can be provided for combining the recording and reading functions. For example, all the blocks B1, B2 can be made integral by mechanical assembly. Thus, after assembling blocks Bl, B2 and shielding screen 48 (if it exists), a recording and reading device called RWW (in English read while write is read during recording). An advantage of such a device is that it makes it possible to check the integrity of the data recorded during the writing. The writing precedes the reading.

Referring to Fig. 4. Instead of the writing block B1 and read block B2 following each other in the axial direction of the tracks 47 of the magnetic recording medium 44, they are stacked one over the other. It is possible to combine a write block Bl formed of several recording heads 4Ow placed on at least one support 1000 to a reading block B2 formed of several read heads 4Or placed on at least support 1001. The read heads 40r and the recording heads 40w are represented by their pairs of pole pieces and their gap e.

In FIG. 4, each block B1 or B2 has only one support 1000 or 1001. The supports 1000, 1001, which are initially distinct, are assembled by arranging the space 33 conditioning the distance d inter-pole piece. The space 33 may contain a magnetic shield and / or an electrical insulator. It can also contain magnetoresistive reading means. This space 33 makes it possible to parameterize the alignment between the magnetic heads of writing and those of reading by its thickness d.

As a variant, the two supports could be one and the same, the magnetic writing heads and the magnetic reading heads would be placed on either side of an insulating layer 33 of the support 63 as illustrated in FIG. 5B. In this case the support is multilayer, it may be for example a SOI type substrate (semiconductor on insulator) or more generally an XOI type substrate where X represents a monocrystalline material. The pole pieces are on both sides of the insulation layer. The outer layers of the common support are comparable to two supports assembled to one another.

In the embodiment of FIG. 4, all the azimuth angles α of the magnetic heads, whether dedicated to writing or to reading, are equal. The two supports 1000 and 1001 have the same inclination angle θ.

An advantage of a recording and / or reading device such as that illustrated in FIG. 4 and in FIGS. 3A, 3B is to facilitate the positioning of the read heads 4Or with respect to the write heads 4Ow. An interpiste referenced 41 is kept to take into account possible misalignment problems called tracking or to insert tracks written by another head or another similar device with a different azimuth angle.

In FIG. 4, the recording and / or reading device represented is RWW (abbreviation of read while write, ie in which reading is done during writing). The magnetic write heads 4Ow and the magnetic reading heads 4Or may have advantageous alignment when the following parameters obey the formula:

P + d = (D + nT) tg (θ) with θ inclination angle of the supports 1000, 1001 with respect to the tracks 47, T longitudinal pitch of the gaps of the pair of pole pieces placed on the same support, D longitudinal offset by relative to the supports between two pairs of consecutive pole pieces placed on two consecutive supports, P width of the pole pieces and n integer. The technical and economic optimization of these magnetic heads will play on the choice of parameters of the formula.

In FIG. 4, the integer n is 1. The distance d can be adjusted without heavy technological constraints. It seems appropriate to choose n ≤2 to limit the size of the magnetic heads, and the distance between the reading and writing gaps.

FIGS. 5A, 5B show in three dimensions, respectively, a conventional recording and / or reading device and according to the invention associated with a magnetic recording medium 64 having substantially parallel linear tracks 61 separated by an interger 62. Interperist 62 has a width w0 in Fig. 5A and a width w1 in Fig. 5B. Recorded information, taking the form of a succession of bits orthogonal to the tracks, is represented on two of the tracks 61.

In these two cases, the recording device comprises a succession of magnetic recording and / or reading heads 60 whose pairs of pole pieces are carried on the same substantially plane support 63.

In these figures, the magnetic heads 60 are represented in their entirety. They each comprise in addition to a pair of pole pieces 50, 51 separated by the nonmagnetic air gap 52, a magnetic flux guide 53 which magnetically couples the two pole pieces 50, 51 of a pair and recording means and / or reading 54 which cooperate with the magnetic circuit consisting of pole pieces 50, 51 and the magnetic flux guide 53.

The recording and / or reading means may be inductive or magnetoresistive. In the examples of FIGS. 5A, 5B, the recording and / or reading means 54 are inductive and take, for each magnetic head 60, the shape of at least one solenoid which surrounds the magnetic flux guide 53.

In Figure 5A, the magnetic circuit is in a plane perpendicular to the support 63, it is substantially horseshoe-shaped and ends at each of its ends by one of the pole pieces 50, 51 of a pair. The gap 52 is directed parallel to the plane of the support 63. These magnetic heads 60 have an azimuth angle α = 90 °, the azimuth angle α is counted relative to a normal to the support. The magnetic recording medium 64 passes in front of the magnetic recording and / or reading heads 60 in the direction indicated by the arrow. The plane of the support 63 is substantially perpendicular to the general direction x of the tracks 61. The inclination angle θ is equal to 90 °, the angle of inclination θ being the angle between the support and the general direction of the tracks.

In contrast, in Figure 5B, the magnetic flux guide 53 has two legs 53.1, 53.2 magnetically connected on one side to a pole piece 50, 51 and the other to a single rear magnetic piece 53.3 closure. The recording and / or reading means 54 take the form of solenoids 54 which cooperate with the legs 53.1, 53.2 of the magnetic flux guide 53. A monolithic magnetic circuit structure could be used in a magnetic head of a magnetic resonance device. recording and / or reading according to the invention.

In FIG. 5B, the support 63 is common for two sets of magnetic heads. They are placed on either side of an insulating layer 33 of the support 63. Thus, this structure can be likened to a structure having two consecutive supports 63.1, 63.2 forming a common support 63 on which two sets of pairs of polar parts are placed on either side of an electrically insulating layer 33 of the common support 63. The magnetic heads are azimuthed, their air gap 52 has an azimuth angle α counted with respect to a direction normal to the plane of the magnetic circuit (plane of the support 63 in Figure 5B). This azimuth angle is between ± 90 ° excluded. The plane of the magnetic circuit (plane of the support 63 in FIG. 5B) is inclined by a non-zero angle θ between ± 90 ° with respect to the general direction x of the tracks 61.

With respect to the structure of FIG. 5A, the structure of FIGS. 2 and 5B can easily lead to closely spaced tracks, that is to say to lesser (wl <wO) or even zero interpiste widths: to choose the angle of inclination θ sufficiently low. In addition, the recorded bits are orthogonal to the general direction of the tracks when α = θ is chosen.

The inter-support layer 33 may be composed of an insulator, for example silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), silicon carbide (SiC), AlSiC (mixture of alumina and silicon carbide), titanium carbide (TiC), AlTiC (mixture of alumina and titanium carbide) or any other insulator with good resistance to corrosion. 'wear. This layer can be made in one or more times, for example by a deposition process using microelectronic equipment or micro or nano technology for example sputtering type (PVD, PECVD ...). In the case of using the insulating layer of an SOI / XOI substrate as an inter-support layer 33, its thickness will be adjusted by the substrate manufacturer by any method of this type of industry. In order to properly assemble the supports 1000 and 1001 of Figure 4, on both sides of the inter-substrate layer 33, it is possible to realize the inter layer ^¬ support on one, the other or both supports 1000, 1001 with, for example, chemical-mechanical planarization steps and appropriate surface preparations for subsequent assembly with precise positioning. The inter-support distance will then of course be the sum of the thicknesses deposited on each support 1000 and 1001. Each of these thicknesses may optionally contain one or more magnetic screens and / or magnetoresistive elements (GMR or more generally XMR) embedded in the insulation 33 (deposited and / or etched by appropriate micro ^¬ technology equipment).

An exemplary method of producing a recording and / or reading device according to the invention similar to that illustrated in FIG. 5B will now be described with reference to FIGS. 6A to 6E. This method is based essentially on the teaching issued by patent applications FR-A-2,664,729 and FR-A-2,745,111 in the name of the applicant. The magnetic heads are made collectively, it is assumed in this example that they are inductive heads. The magnetic heads are made on substrates, they correspond to the supports that have been described previously.

In the examples, the recording and / or reading device comprises two substrates each carrying three magnetic heads. In a real device there will be many more magnetic heads of the order of several hundred for example.

It starts from a substrate 100 with an electrically insulating layer 102 sandwiched between two outer layers 101, 103 of which at least one is made of monocrystalline material.

It may be a semi ^¬ conductive type on-insulator substrate, for example a SOI substrate (silicon on insulator). Recall that such a substrate consists of an electrically insulating layer 102 sandwiched between two semiconductor layers 101, 103. Generally one of the semiconductor layers is thicker than the other. Such a semiconductor on insulator substrate is however not mandatory.

Advantageously, the other outer layer 101 may be made of a material resistant to wear, this material may be neither semiconductor nor monocrystalline. It can be made for example of zirconia ZrO ₂ , AlSiC silicon carbide and alumina, AlTiC titanium carbide and alumina, alumina Al ₂ O ₃ or other. This outer layer 101 is advantageously thicker than that which is monocrystalline.

The fact that at least one of the outer layers is monocrystalline will be used to make engravings conditioning the azimuth angle of the air gaps. So we choose its orientation crystallographic as a function of the desired azimuth angle.

The pairs of pole pieces 106, 108 of each magnetic head, the gaps e, as well as the rear magnetic closing pieces 55.3 which are parts of the flux guide of the magnetic circuit of each of the magnetic heads of the magnetic head, will first be produced. recording and / or reading device.

In the outer monocrystalline layer 103 is etched first flared casings 104 to house one of the pole pieces of each pair of pole pieces to be on this first substrate (Figure 6A). This etching is, for example in the case of silicon, an anisotropic wet chemical etching, for example in a KOH potash bath. The inclination of one of the flanks of each first caisson conditions the value of the azimuth angle α. This azimuth angle is the same for all air gaps that will be made. This inclination takes advantage of the monocrystalline nature of the substrate, the anisotropic etching taking place along a crystallographic plane of the substrate. In silicon, it is the <111> family planes that limit the etching edges. These substrates are commercially available. This process is described, for example, in document FR-A-2,664,729.

The layer of electrically insulating material 102 of the substrate 100 serves as a stop layer during the etching of the first caissons 104. The thickness of the semiconducting surface layer 103 of the substrate 100 determines the width of the pole pieces of the pairs on this first support.

A layer 105 of non-magnetic material, of substantially uniform thickness, is then formed on the flanks of the first caissons 104. In the case where the first caissons are made of silicon, it is possible to carry out a surface thermal oxidation of the first substrate as well as worked (Figure 6A). One could have alternatively deposit the non-magnetic material on the flanks of the first boxes.

The layer 105 of non-magnetic material which lines one of the flanks flared of each of the first boxes 104 will constitute the azimuth gap e of each pairs of polar parts on the substrate 100.

An electromagnetic material is deposited, for example by electromagnetic material, in the first boxes 104. The magnetic material may or may not be laminated, for example an alloy of NiFe, CoFe or CoFeX where X represents a suitable material such as Cr, Cu Or other.

The surface of the substrate 100 thus worked is planarized so that the oxide is flush and that the magnetic material has the desired thickness

(Figure 6B). This magnetic material forms a first pole piece 106 of each pair of pole pieces.

Isotropic is then etched second boxes 107 to accommodate the other pole piece of each pair of pole pieces to be on the first substrate 100 (Figure 6C). These seconds caissons 107 are contiguous with the first caissons 104 and are all on the same side of these first caissons 104. In the example, they are on the left of the first caissons 104. They could be on the right. The angle of azimuth would then be different, it would be another plane of the family <111>. The monocrystalline material of the surface layer 103 which is close to the air gap e is removed by etching. The non-magnetic material of the gap e serves as a flank for these second boxes 107.

It is also possible to engrave during this step, third boxes 128 to accommodate magnetic magnetic circuit closing rear parts that will be completed later. These third boxes 128 are located in front of each pair of pole pieces 106, 108. Reference can be made to FIG. 6E which shows in plan view the pairs of pole pieces 106, 108 and the rear magnetic closure pieces 55.3.

The depth of these second boxes and third boxes is substantially the same as that of the first boxes because of the stop layer 102 which limits the two engravings.

These second boxes 107 and third chambers 128 are filled with magnetic material and are terminated by a planarization step as previously described (FIG. 6D). The magnetic material forms the second pole piece 108 of each pair and the rear magnetic piece 55.3 closing. This planarization step makes it possible to finally adjust the width P of pairs of pole pieces. It also allows to equalize the surface of the pole pieces of each pair giving them a very good alignment on their upper face (in Figure 6D) their lower face, resting on the insulating layer 102, being already flat and having a very good alignment.

We will now realize the rest of the flow guide of the magnetic circuit of each of the magnetic heads of the device, that is to say, in this example, the magnetic legs that magnetically connect the two pole pieces of a pair to the piece magnetic rear closure and the recording means and / or reading. The method employed is based on the teaching of the patent application FR-A-2,745,111.

It will be recalled that in this example, the recording and / or reading means are solenoids that surround the magnetic circuit at the level of the legs or branches of the horseshoe. Referring to Figures 7A-7E. Figures 7A-7D are sections along a leg of the magnetic circuit.

There is a second substrate 130, called additional, with a base layer 131 for example semiconductor covered with a layer of electrically insulating material 132. It could very well use a bulk substrate (in English bulk) for the layer base 131, possibly resistant to wear.

We will start by forming for each solenoid a first layer of conductors that will extend between a pole piece and a closing rear magnetic piece or along a branch of the magnetic circuit horseshoe. For this, in the insulating layer 132, at the locations where should be solenoids, first parallel grooves 134 directed substantially perpendicular to the axis of the magnetic cores of the solenoids. These cores correspond to the legs 53.1, 53.2 illustrated in FIG. 5B.

These first grooves 134 are filled by depositing, for example by electrolysis, a conductive material 135, for example copper-based (FIG. 7A). This conductive material 135 forms conductor portions of the first layer of conductors.

A planarization is then carried out, for example mechanical or preferably mechano-chemical, to remove the superfluous conductive material 135 located above the grooves 134.

An electrically insulating layer 136, for example silicon oxide, for example PECVD, is deposited over the entire planarized surface with a thickness greater than that desired for the legs. The insulating layer 136 is etched to reveal caissons 133 at the legs of the magnetic circuit that is to be made. The bottom of these boxes 133 has a sufficient thickness to electrically isolate the conductors of the first layer of conductors of the magnetic circuit. In these boxes 133 is deposited a magnetic material 137 optionally laminated as indicated above for producing the pole pieces (Figure 7B). The surface obtained is planarized as explained above.

Lateral conductors of the solenoids will now be made. We lay a layer electrically insulating 138 on the planarized surface (for example silicon oxide by PECVD). Wells 139 are etched in the insulating layers 138 and 136 until the ends of the conductors 135 of the first layer of conductors are reached. These wells 139 are filled, for example by electrolysis, with conductive material 140, for example copper-based (FIG. 7C). Planarize the resulting surface. This conductive material forms the lateral conductors 140 of the solenoids.

FIG. 7D then produces a second horizontal layer (in the figure) of solenoid conductors by depositing a layer of electrically insulating material 141 on the surface of the structure obtained, by etching second grooves 142 in this material, the ends of which the lateral conductors 140 thus produced. The second grooves 142 are filled with conductive material 143 based on copper deposited for example by electrolysis. Planarize the resulting surface. The conductive material 143 forms the conductors of the second conductor ply of the solenoids. The conductive material 143 is covered with a layer of electrically insulating material 144. It is intended to make contact resumptions at the ends of the conductor of the solenoids (not visible).

In FIGS. 7C and 7D, it has been shown, by showing the boxes 133 in dotted lines, that they are not in the same plane of section as the wells 139. These are just "in front" of the boxes 133, they do not cross the magnetic material 137 which fills the boxes but the material of the insulating layer 136. As for the grooves 134, they are not quite perpendicular to the axis of the boxes 133.

FIG. 7E illustrates with a scale other than those of FIGS. 7A to 7D and in side view with respect to FIG. 7D the configuration of the second substrate 130 ready to be assembled to the first substrate 100.

The second substrate 130 may optionally accommodate signal processing means delivered or acquired by the magnetic heads.

Positioning is aligned and assembles the second substrate 130 of Figure 7E and the first substrate shown in Figure 6D, after turning one of them. Care is taken to magnetic contact the legs of the magnetic circuit on one side with the pairs of pole pieces and the other with a magnetic rear closure part.

The assembly can be done by any technique known to those skilled in the art in the field of micro-technologies and in particular electromechanical microsystems (MEMS).

Advantageous assembly methods are bonding with glue, anodic bonding, and direct bonding as described in FR-A-2,774,797 or microbead bonding. (English bail bonding or flip chip bonding). In FIG. 8A, the second substrate 130 has been assembled by molecular bonding or other, with alignment, so that the magnetic circuits 137 are magnetically connected each with a pair of pole pieces 106, 108, this connection being made directly. The alignment can be done by infrared sighting for example or under X-rays.

It remains only to eventually totally or partially eliminate the base layer 131 of the second substrate 130 (Figure 8B), for example by complete or local selective etching of the material of this base layer 131 with a stop on the insulating layer 132. It is thus possible to make contact resumptions through the insulating material of the layer 132 for feeding the recording and / or reading means (the solenoids formed by 135, 140, 143 in this particular case).

It may be advantageous to preserve the unworked layer 101 of the first substrate 100, in which case it may advantageously be made of a material resistant to wear, for example AlTiC, ZrO ₂ , AlSiC.

Instead of making the rest of the flux guide of each of the magnetic heads as well as the recording and / or reading means on the additional substrate, they could have been made on the first substrate 100 at the stage of FIG. 6D, following the steps described in FIGS. 7A to 7E. A structure obtained in this way would be similar to that of Figure 8B. It is then superfluous to show the various steps leading to such a structure, it is sufficient to refer to the description of FIGS. 7A to 7E, with the difference that the electrically insulating layer 132 will be deposited on the first substrate 100 at the stage of FIG. 6D. For example, silicon oxide can be deposited by PECVD.

The structure obtained in FIG. 8B is then processed so as to give the substrates a given angle of inclination θ with respect to the magnetic tracks of the magnetic recording medium.

This treatment can consist of an integration of one or more blocks (or chips) of magnetic heads on a common mechanical support. We can refer to Figure 9. Beforehand, we perform a test of the magnetic heads and cut the structure of Figure 8B blocks (or chips) 300, 301. Indeed, as we saw previously, we collectively made several hundred magnetic heads. One or more of these blocks 300, 301 are mounted on the same mechanical support 350. This step is known by the English name of "back-end" or "packaging". The mechanical support 350 will advantageously be made of a material resistant to wear such as for example AlTiC (titanium carbide and alumina) which is commonly used by manufacturers of linear magnetic heads.

The contour of the mechanical support 350 is then rectified, for example at its faces 351 so that the first substrate 100 can have an angle of inclination. θ desired with respect to the tracks 47 of the magnetic recording medium 44.

We could of course do without mechanical support. The structure of FIG. 8A could be directly corrected before or after the chip blanking in order to reveal the angle of inclination θ, especially if it is small, on the external faces of the substrates 100 and 110. in this case, electrical contact resumption will be advantageously by local etching.

A second embodiment of a recording and / or reading device according to the invention will be described, this device is illustrated in FIG. 10. It is a device called in English read while write in which reading is done during writing. This device is particularly interesting because it makes it possible to check the integrity of the data recorded during the recording.

The device according to the invention comprises first magnetic heads 90 dedicated to writing and second magnetic heads 91 dedicated to reading. These first and second magnetic heads form an alternating succession, that is to say that in the succession a first magnetic head 90 is close to a second magnetic head 91.

The first pairs of pole pieces ppll, ppl2 of the first magnetic heads 90 are distributed on a substrate 93 and the second pairs of polar parts pp21, pp22 second magnetic heads 91 are distributed on another substrate 94, the two substrates are stacked. The first and second magnetic heads 90, 91 are azimutated and they all have the same azimuth angle α defined as explained above.

The recording means of the first recording magnetic heads 90 take the form of solenoid sl.l, si.2, whereas the reading means of the second magnetic reading heads 91 are of magnetoresistance type and take the form of minus a bar g, for example GMR material.

The flow guide cl, c2 of the magnetic circuit of each of the first and second magnetic heads 90, 91 magnetically connects the pole pieces ppll, ppl2, pp21, pp22 of a head 90, 91 respectively. This flow guide c1, c2 may comprise two legs jl.l, jl-2, J2.1, j2.2 magnetically connected on one side to a pole piece ppll, ppl2, pp21, pp22 and on the other side to a single magnetic rear piece al, a2 closing. The connection between legs J1, J1, J2.1, J2.2 and the pole pieces ppl1, ppl2, pp21, pp22 can be direct or via magnetic pads pl.l, pi. 2 connection depends on the substrate on which are the pole pieces of the magnetic head.

As a variant, the flux guide of the magnetic circuit could be monolithic, substantially in the form of a horseshoe or the like of which each end would be magnetically connected to a pole piece.

Referring to Figures HA to HD.

Starting from a first substrate 1000 with an electrically insulating layer 1002 sandwiched between two outer layers 1001, 1003 of which at least one 1003 is monocrystalline material.

It may be a semi ^¬ conductive type on-insulator substrate, such as a SOI type substrate. Such a semiconductor on insulator substrate is however not mandatory.

Advantageously, the other outer layer 1001 may be made of a material resistant to wear, this material may be neither semiconductor nor monocrystalline. It may be made for example of ZrO ₂ zirconia, AlSiC (silicon carbide and alumina), AlTiC (titanium carbide and alumina), alumina Al ₂ O ₃ or other. This outer layer 1001 is advantageously thicker than that which is monocrystalline.

The first pairs of polar parts ppll, ppl2 of the first magnetic heads 90 will be made. The first 1004 single-crystal layers 1003 are etched in the monocrystalline layer to house one of the pole pieces of each first pair of pole pieces to be on this first substrate. 1000 (Figure HA). As in the example described in FIG. 6, the thickness and the crystallographic orientation of the monocrystalline layer 1003 are chosen to give the first pole pieces the desired thickness and the desired azimuth angle. This etching is an anisotropic etching similar to that described in FIG. 6A, which is why it is not described any more.

A layer 1005 of non-magnetic material is then formed, for example by surface thermal oxidation of the first substrate 1000 as well as worked (Figure HA) when its layer 1003 is silicon. The substrate 1000 may be formed of the silicon layer 1003. The layer 1005 of non-magnetic material which lines one of the flanks flared of each of the first caissons will constitute the air gap azimuth e of each of the first pair of polar pieces that will be on this substrate 1000.

For example, by electrolysis, a magnetic material, laminated or not, is deposited in the first boxes 1004. The magnetic material may be, for example, an alloy of NiFe, CoFe or CoFeX where X represents a suitable material such as Cr, Cu Or other.

The surface of the substrate 1000 thus worked is optionally planarized so that the oxide is flush and that the magnetic material has the desired thickness (Figure HB). This magnetic material forms a first pole piece ppll of each first pair of pole pieces.

Isotropic is then etched second boxes 1007 to accommodate the other pole piece ppl2 of each first pair of pole pieces to be on the first substrate 1000 (Figure HC). These second boxes 1007 are contiguous to the first boxes 1004 and are all on the same side of these first boxes 1004. In the example, they are on the right of the first boxes 1004. They could be on the left.

The monocrystalline material of the outer layer 1003 which is close to the gap e is removed by etching. The non-magnetic material of the air gap serves flank to these second boxes 1007. The depth of these second boxes is substantially the same as that of the first boxes because of the insulating layer 1002 which serves as a barrier layer.

These second boxes 1007 are filled with magnetic material, laminated or not, by electrolysis and a planarization step is completed as described above (FIG. HD). This magnetic material forms a second pole piece ppl2 of each first pair of pole pieces. This planarization step makes it possible to finally adjust the width of the pole pieces and to align their edges.

The second pair of polar pieces pp21, pp22 of the second magnetic heads 91 will now be made. Reference is made to FIG. 12A. Starting from a second substrate 1100 having an insulating layer 1120 buried between two outer layers 1110, 1130 at least one of which is monocrystalline (for example an SOI substrate). The explanations on the choice of the first substrate and the thickness of its monocrystalline layer apply for the second substrate.

In the monocrystalline layer 1130 anisotropic etching is carried out of the first boxes 1140 which are filled with magnetic material (laminated or not) by providing a step of forming a layer of non-magnetic material, (for example by superficial thermal oxidation in the case of silicon), before filling and planarization as described in Figures HA and HB. The nonmagnetic material layer has the reference 1150 and one of the second polar parts the reference pp22. The portion of material non-magnetic 1150 on one of the flanks of the first caissons 1140 will form the gap e second pairs of polar parts.

Second boxes 1170 are made by isotropic etching as described in FIG. The second caissons 1170 adjoin the first caissons 1140 and are all on the same side of these first caissons 1140. In the example, they are on the right of the first caissons 1140 as explained previously in the realization of the first pairs of polar parts on the first substrate 1000. They could be on the left, it depends in particular on the relative movement that is desired to perform during the reversal of one of the substrates relative to the other at the time of assembly. The position of the second boxes 1170 also depends on the final azimuth angle of pairs of pole pieces located on the second substrate. His sign can thus change during the subsequent step of assembling the first substrate to the second substrate.

At the same time, pairs of third boxes 1180 can be made at the same time, between the groups of first and second boxes 1140, 1170, intended to house the pairs of magnetic connection pads pl.l, pi.2 each intended to magnetically connect the pole pieces. ppll, ppl2 of the first pairs of pole pieces located on the first substrate 1000 to the magnetic circuit finalized later. These third boxes 1180 are positioned so that the magnetic pads of a pair are magnetically connected to the pole pieces ppll, ppl2 a first pair of pole pieces when the first substrate 1000 and the second substrate 1100 are assembled to each other after turning one of them. A rotation of 180 ° about an axis transverse to the substrate may optionally be introduced so that the desired azimuth angles on the two substrates are obtained.

At this stage, it is still possible to carry out, by isotropic etching, fourth rear boxes 1210 intended to house the rear closure magnetic pieces al, a2 which are parts of the magnetic circuit of each of the first and second magnetic heads of the recording device and / or reading. These rear parts are visible in Figure 12B which is a view from above. These fourth boxes 1210 are positioned so that the closing rear magnetic parts al, a2 are opposite first and second pairs of pole pieces ppll, ppl2, pp21, pp22. They are at the same level as the second pairs of polar pieces pp21, pp22 but not at the same level as the first pairs of polar pieces ppll, ppl2. 12B shows in partial top view pairs of magnetic pads pl.l, pi.2 and closing magnetic rear parts al, a2. The realization of these fourth boxes 1210 takes all its importance when the magnetic circuit has two magnetic legs and a magnetic rear closing part. This step is superfluous when the magnetic circuit is monolithic. These second caissons 1170, third caissons 1180 and fourth caissons 1210 are filled with magnetic material (laminated or not) as described in FIG. HD and a planarization of the surface is carried out. The magnetic material will form in the end on the one hand the second pole pieces pp21 second pairs of pole pieces and secondly the connection pads pl.l, pi.2.

The azimuth angle of the air gaps e of the first and second pairs of pole pieces has been suitably adjusted. These azimuth angles will be equal at the moment of their realization since in the final after assembly of the substrates 1000 and 1100, the azimuth angles must be equal and of the same sign. It has also been desired to adjust the width of the pole pieces which is not necessarily equal from one substrate to another. Magnetic reading heads often read only part of the written track.

It is advantageous before resorting to the assembly of the two substrates, to deposit on the surface of at least one of the substrates 1000, 1100, an insulating layer 500 (for example of silicon oxide) and / or a shielding layer magnetic and prepare the surface to adjust the inter-piece polar distance. This layer 500 also makes it possible to optimize the assembly of the substrates. The material of the insulating layer may advantageously be in a material resistant to wear so as to limit the wear of the recording device and / or reading. His choice may also facilitate the assembly of substrates. It will be possible advantageously to leave apertures in the shielding layer 500 at the magnetic pads pl.l, pi.2, that the shielding layer is located on one and / or the other of the substrates.

The insulating layer 500 on the read head side may also contain magnetoresistive reading means, which is particularly advantageous for the magnetoresistive bars (MR, GMR) directly coupled to the pole pieces. They are shown in Figure 14C.

We will then position with alignment and assemble the first substrate 1000 and the second substrate 1100 by their worked faces, after turning one of them. Care is taken to align each magnetic pad pl.l, pi.2 with a pole piece ppll, ppl2 of the first substrate. This alignment can be done by infrared sighting, for example or under X-rays. The reversal of one of the substrates 1000 or 1100 can cause the sign change of the azimuth angle of the pairs of polar pieces that are on this substrate. . It depends on how you do it. If there is both reversal and 180 ° rotation of the substrate around a transverse axis there will be sign change.

The assembly can be done by any technique used in micro-technologies known to those skilled in the art or by molecular assembly as described in the first embodiment. Another particularly interesting method of assembly is the assembly by conductive fusible beads (English flip chip bonding). The figure 12C schematically illustrates the two substrates 1000, 1100 as shown in Figures 10D and HA respectively about to be assembled by beads 230 fusible alloy.

This solution makes it possible to have a very precise alignment (submicron) in X - Y and to be able to ensure electrical connections between the different substrates. The patent application FR-A-2 807 546 describes this method of assembly for particular printheads that is why we do not give more details here.

The untreated layer 1110 can then be removed from the second substrate 1001. This removal can be carried out selectively, for example by etching with, for example, potassium hydroxide KOH or by chemical mechanical etching with stopping on the buried insulating layer. 112 (Figure 12D). If necessary, it may be necessary to thin the buried insulating layer 1120 to reveal or almost appear the second pair of polar pieces pp21, pp22 and the pairs of magnetic pads pl.l, pi.2.

Referring to Figures 13A and 13B. We will now realize the rest of the flow guide of each of the magnetic heads, ie in this example the magnetic legs jl.l, jl.2, J2.1, J2.2, and the recording means and / or reading which are in the form of solenoids s11, sl2 for the first magnetic heads 90 and in the form of a bar g for example of material GMR for the second magnetic heads. If in Figure 12A, the rear magnetic closing parts have not been realized, the circuit Monolithic magnetic will be substantially horseshoe shaped. The method employed is inspired by that described in patent application FR-A-2 745 111.

The embodiment of the legs and solenoids is similar to what has been described in FIGS. 7A-7E, which is why it is not fully described again. There is a third substrate 1300 (called additional substrate) with a base layer 1310 (for example semiconductive or resistant to wear) covered with a layer of electrically insulating material 1320. One could very well use a substrate massive (in English bulk) electrically insulating or covered with insulation. The procedure is as described in FIGS. 7 and 7C. However, the engravings of the boxes to accommodate the conductors 134, 139 are not carried out at the locations where the legs 137 are to cooperate with the bars g of material GMR.

On the other hand, on each of the legs J2.2 concerned, an air gap is made by any known means of the state of the art, for example by producing two adjacent sub-boxes 133 'instead of one in the insulating layer 136. These sub-boxes are illustrated in Figure 13A. The sub-boxes 133 'are filled with magnetic material (laminated or not) and planarized. The deposition of the insulating layer 138 of FIG. 7C will be done in several steps. A thin insulator layer 138a (typically a few nanometers) is deposited on the planarized surface, for example by spraying. A layer of GMR material is then deposited. We engrave this layer where we want remove GMR material. The remaining GMR material is referenced g. It can be a dry etching for example. Another insulating sub-layer 138b is then deposited to complete the layer 138. The solenoid coils can be continued as described in FIGS. 7C, 7D. It is not necessary to describe these steps. By a similar method, the bars g of material GMR could be made under the legs j2.2.

FIG. 13B shows, in the manner of FIG. 7E, the third substrate 1300 with a base layer 1310 (for example semiconducting) covered with a layer of electrically insulating material 1320 supporting the magnetic legs jl.l , J1.2, J2.1, J2.2, the solenoids s11, sl2 and the bars g made of GMR material.

In Figure 14A is positioned with alignment and assembles the third substrate 1300 and the structure shown in Figure 12D, after turning one of them. The assembly can be done by one of the methods described above. The insulating layer 1120 may be partially or completely removed. The layers 1120 and 1320 being of the same nature, it is not necessarily beneficial to eliminate the layer 1120 because it may be useful for molecular bonding. Chemical mechanical polishing can remove some of it.

In Fig. 14A, the third substrate 1300 has been assembled by molecular bonding or the like with alignment. Thus the magnetic circuits jl.l, jl.2 are magnetically connected each with a pair of polar pieces ppll, ppl2 via a pad magnetic pl.l, pi.2 and both with a magnetic closure part al. Similarly, the magnetic circuits J2.1, J2.2 are magnetically connected each with a pair of pole pieces pp21, pp22 and both with a magnetic closure piece. It remains only to partially or completely eliminate the base layer 1310 of the third substrate 1300 (FIG. 14B), for example by selective etching of the semiconductor material with a stop on the insulating layer 1320. contact through the insulating material of the layers 1320 and following for the supply of the recording and / or reading means (solenoid sl.l, si.2 and bars g GMR material). FIG. 13A and FIGS. 13B and 14A, 14B are sections made in different planes, for this reason the air gap eg is visible only in FIG. 13A.

We can then proceed to the mounting of one or more chips of multiple magnetic heads on the same mechanical support as described in Figure 9. It is then also rectified, as explained in the description of this figure 9.

FIG. 14C illustrates another example of a recording and reading device according to the invention derived from the example of FIGS. 14A, 14B. In this example, the first pairs of polar pieces ppll, ppl2 are dedicated to reading and the second pairs of polar pieces pp21, pp22 are dedicated to the recording. The layer 500 inserted between the first substrate 1000 and the second substrate 1100 contains a magnetic shielding screen 600. magneto-resistive reading means g cooperate with the first pairs of polar pieces ppll, ppl2. They take the form of bars of material MR or GMR for example and are located in the layer 500, on the side of the first substrate 1000 relative to the shielding screen 600.

Magnetic circuits J2.1, J2.2 similar to those described in Figures 7 are magnetically connected to the second pair of polar parts pp21, pp22. They are located in the insulating layer 1320 of the third substrate 1300. Recording means s2.1, s2.2 inductive type similar to those described in Figures 7 cooperate with the second pairs of polar parts pp21, pp22. They are also located in the insulating layer 1320 of the third substrate 1300.

Compared to the example of FIGS. 14A and 14B, the magnetic connection pads pl.l, pi.2 are absent.

Signal processing means 302, for example preamplifier circuits, multiplexers, demultiplexers, cooperate with reading means g and / or recording s2.1, s2.2. They are made in a substrate 400 which overcomes the third substrate 1300 or in a layer of the third substrate 1300 if it is multilayered. They could be mounted on the surface of the third substrate 1300. They are positioned and aligned with the reading means and the recording means. They are electrically connected to the reading and recording means via connection via 303 which pass through the third and second substrates 1300 and 1100. It is understood that such signal processing means would cooperate with reading means in the case of a read-only device or with recording means in the case of a recording device alone.

As a variant, in the case where the pairs of pole pieces are distributed over several substrates, the recording and / or reading means can also be made on several substrates. Referring to FIG. 15, first pairs of pole pieces 1060, 1080 are made on a first substrate 1500, for example as described in FIGS. 6A to 6D. A second substrate 1800 (said additional substrate) is made of first flux guides 21, 21 of magnetic circuits (at least partially) and first recording and / or read means sl.l, if. 2 as described for example in Figures 7 or 13A.

Positioning is aligned and the first substrate 1500 and the second substrate 1800 are assembled after turning one of them so that each of the first magnetic flux guides 21 is connected magnetically with a first pair of polar pieces 1060, 1080.

A second substrate 1600, second pairs of pole pieces 1160, 1190 and, on a fourth substrate 1700 (so-called additional substrate), second magnetic flux guides J2.1, j2.2 and second means of diffusion are produced in the same way on a third substrate 1600. recording and / or reading s2.1, s2.2. We position with alignment and assemble the third substrate 1600 and the fourth substrate 1700, after turning one of them so that each of the first magnetic flux guides J2.1, j2.2 is magnetically connected to one of the first pairs of pole pieces 1160, 1190.

The unworked layer 1510, 1610 and the dielectric material layer 1520, 1620 (at least partially) of the first substrate 1500 and the third substrate 1600 are eliminated.

At least one layer of insulating material 500 is deposited on the faces carrying the pairs of pole pieces of the two previously obtained structures. This layer can contain a shielding screen

We position with alignment and assemble the two structures by their faces that have just been worked after turning one of them, taking care to place the first pair of pole pieces and second pairs of pole pieces staggered. Assembly and alignment can be done as previously described in Figure 10C. It is possible to eliminate one of the non-worked layers 1700, 1800 and / or the second one by chemical etching for example.

Repetitions of electrical contacts (not shown) of the recording and / or reading means can be done using an intra-connection technology or for example by local etching (dry or wet).

It is of course possible to dispense with the second substrate and / or the fourth substrate (that is, to say additional substrates) as explained above by directly producing the flux guides and the recording and / or reading means on the first substrate 1500 and on the third substrate 1600 respectively after any thinning.

Although several embodiments of the present invention have been shown and described in detail, it will be understood that various changes and modifications can be made without departing from the scope of the invention.

The different variants described must be understood as not being exclusive of each other.

Claims

1. Device for recording and / or reading a magnetic medium (35) with magnetic tracks (36), comprising a plurality of magnetic heads (30.1 to 30.4) each comprising a pair of pole pieces separated by a gap (e) non-magnetic, characterized in that these pairs of pole pieces are grouped on several supports (1000, 1001) superimposed, having a non-zero angle of inclination (θ) of between ± 90 ° with respect to the tracks, all the gaps (e) pairs of pole pieces of the support (1000) having the same azimuth angle (α), between ± 90 ° excluded from a normal direction to the carrier (1000), at least two consecutive carriers (1000, 1001) defining a distance (d) inter-pole piece non-zero, this distance (d) being the distance between facing planes facing polar pieces located on the two supports.

2. Recording and / or reading device according to claim 1, characterized in that the superposition is via a layer (33) capable of precisely defining the distance (d) inter-pole piece.

3. Recording and / or reading device according to one of claims 1 or 2, characterized in that the inter-piece polar distance is such that: P + d = (D + nT) tg (θ) with θ inclination angle of the supports with respect to the tracks, T longitudinal pitch of the pairs of pairs of pole pieces placed on the same support, D longitudinal shift with respect to the supports between two pairs of consecutive pole pieces placed on two consecutive supports, P width of the pole pieces and n integer.

Recording and / or readout device according to one of Claims 1 to 3, characterized in that a magnetic shielding (600) and / or magnetoresistive reading means (g) are inserted between the two supports ( 1000, 1001) in a space corresponding to the distance (d) inter-pole piece.

5. Recording and / or reading device according to one of claims 1 to 4, characterized in that the azimuth angle (α) and the angle of inclination (θ) are equal in module.

Recording and / or readout device according to one of Claims 1 to 4, characterized in that the azimuth angle (α) and the angle of inclination (θ) are different.

7. A recording and / or reading device according to one of claims 1 to 6, characterized in that it comprises at least two consecutive supports respectively having different angles of inclination (θl, Θ2).

8. A recording and / or read device according to claim 7, characterized in that the azimuth angles (α1) of the air gaps of the pair of pole pieces of one of the supports are different from the azimuth angles (α2). ) pairs of polar pieces on the other support.

9. Recording and / or reading device according to one of claims 1 to 8, characterized in that two pairs of pole pieces (4Ow, 4Or) belonging to different supports (1000, 1001) cooperate with two magnetic tracks. consecutive (47) to read or record.

10. A recording and / or reading device according to one of claims 1 to 9, characterized in that it comprises at least one block (B1) of at least one support (1000) for recording and at least one block (B2) of at least one support (1001) for reading, these blocks being arranged one after the other in the direction of the tracks (47).

11. A recording and / or read device according to one of claims 1 to 10, characterized in that it comprises at least one block (Bl) of one or more media for recording and at least one block (B2) one or more supports for reading, the supports of these blocks being secured to one another.

Recording and / or readout device according to one of Claims 1 to 11, characterized in that each track (47) is recorded and read respectively by a pair of pole pieces (4Ow, 4Or), the pair of polar pieces for recording and the pair of polar pieces for reading belonging to different media (45, 46).

Recording and / or read device according to one of Claims 10 to 12, characterized in that a block (B2) for reading is separated from a block for recording (B1) by a screen shielding (48).

14. A recording and / or reading device according to one of claims 1 to 13, characterized in that it comprises for each magnetic head a magnetic circuit incorporating a pair of pole pieces (ppll, ppl2) and possibly a guide magnetic flux (cl), this magnetic circuit cooperating with recording and / or reading means (sl.l, si.2, g).

15. A recording and / or read device according to claim 14, characterized in that the recording and / or read means (sl.l, si.2, g) and the possible magnetic flux guide for each magnetic head is on an additional support (130) assembled to the support carrying the pairs of pole pieces of the magnetic head.

16. Recording device and / or reading according to one of claims 14 or 15, characterized in that the recording means and / or reading are inductive or magnetoresistive.

Recording and / or readout device according to one of Claims 1 to 16, characterized in that signal processing means (302) cooperate with the recording and / or read means (s2.1). , s2.2, g)

18. A method of producing a recording device and / or reading on a magnetic strip magnetic medium characterized in that it comprises the following steps: on several substrates (1000, 1001) realization of several pairs of polar parts

(108, 106) of magnetic heads, these pole pieces being separated by a nonmagnetic air gap (e), the air gaps (e) of these pairs of pole pieces on the same substrate, all having the same azimuth angle

(α) between ± 90 ° excluded, with respect to a direction normal to the substrate; assembling the substrates by superimposing them so as to define between two consecutive substrates a non-zero inter-piece spacing (d), this distance (d) being the distance between facing planes of polar parts located on the two supports ; performing recording and / or reading means (135, 140, 143) and possibly magnetic flux guides (137) able to cooperate each with a pair of pole pieces; processing the substrates (1000, 1001) to give them a non-zero inclination angle (θ) of between ± 90 ° with respect to the magnetic tracks.

19. The method as claimed in claim 18, characterized in that the recording and / or reading means (135, 140, 143, g) and the possible magnetic flux guides (137) are made on at least one additional substrate ( 130) which is assembled after positioning with the substrate (1000, 1001) carrying the pairs of pole pieces with which they cooperate.

20. The method of claim 19, characterized in that the recording means and / or reading and any magnetic flux guides are formed on the substrate carrying pairs of pole pieces.

21. Method according to one of claims 18 to 20, characterized in that the treatment consists in performing a grinding of one or more substrates.

22. Method according to one of claims 18 to 20, characterized in that the treatment consists in mounting one or more parts of one or more substrates or the substrate or substrates (1000, 1001) in the same mechanical support (350) .

23. Method according to one of claims 18 to 22, characterized in that the substrates (1000, 1100) carrying pairs of pole pieces, are assembled after alignment.

24. The method of claim 23, characterized in that a layer of electrically insulating material (500) optionally comprising magneto-resistive reading means (g) and / or a magnetic shielding screen (600) is inserted between two consecutive substrates bearing pairs of polar pieces.

25. The method of claim 23, characterized in that wedges (49) are inserted between two consecutive substrates carrying pairs of pole pieces.

26. Process according to one of the claims

18 to 25, characterized in that it consists in producing, on one of the substrates, pairs of magnetic studs (pl.l, pi.2) of connection intended to magnetically connect each, a flux guide or a means recording and / or reading to a pair of pole pieces carried by an identical or different substrate.

27. Method according to one of the claims

19 or 23, characterized in that the assembly of two substrates (1000, 1100) is done after turning one of them.

28. Method according to one of claims 18 to 27, characterized in that at least one substrate (1100) is thinned.

29. Method according to one of claims 18 to 28, characterized in that substrates bearing pairs of pole pieces have different angles of inclination.

30. The method according to claim 29, characterized in that the azimuth angle of the air gaps of pairs of polar parts of a substrate is different from the azimuth angle of the air gaps of pairs of polar parts of another substrate. .

31. Method according to one of claims 18 to 30, characterized in that a pair of pole pieces (ppll, ppl2) is produced by anisotropically etching a first box (1004) in the substrate, forming a non-magnetic layer. (1005) on the substrate, by filling the first box with magnetic material, by isotropically etching a second box (1007) which adjoins the first box, filling the second box with magnetic material.

32. The method of claim 31 connected to claim 26, characterized in that to obtain the pairs of magnetic studs (pl.l, pi.2) is made by isotropic etching, pairs of boxes in the substrate to accommodate the pairs magnetic studs and fill the pairs of boxes of magnetic material.

33. Method according to one of claims 31 or 32, characterized in that a surface planarization is performed after any one of the magnetic material filling steps.

34. Method according to one of claims 31 to 33, characterized in that the substrate (1000) carrying pairs of pole pieces (ppll, ppl2) is formed of electrically insulating material (1002) located between two layers (1001, 1003). ), one of which comprises the boxes is monocrystalline, the other possibly being eliminated partially or completely later.

35. The method of claim 34, characterized in that the substrate carrying pairs of pole pieces is formed of electrically insulating material between a layer of wear-resistant material and a layer of monocrystalline material comprising the boxes.

36. Process according to one of claims 19 to 35, characterized in that the assembly is done by gluing, by molecular assembly, by anode assembly or by fusible beads.

37. The method of claim 19, characterized in that the additional substrate within which will be the recording means and / or reading and possible magnetic flux guides is optionally multilayer with a layer of electrically insulating material.

38. The method of claim 19, characterized in that the additional substrate within which will be the recording means and / or reading and possible magnetic flux guides, comprises a layer of wear-resistant material possibly covered of electrically insulating material.

39. Method according to one of claims 18 to 38, characterized in that it comprises a step of producing signal processing means (302) which cooperate with the recording means and / or reading (g, s2 .1, s2.2).