EP1125288A1

EP1125288A1 - Magnetoresistive devices, giant magnetoresistive devices and methods for making same

Info

Publication number: EP1125288A1
Application number: EP99969526A
Authority: EP
Inventors: Glenn L. Beane; David S. Lashmore; Xonglu Hua
Original assignee: Materials Innovation Inc
Current assignee: Materials Innovation Inc
Priority date: 1998-09-24
Filing date: 1999-09-24
Publication date: 2001-08-22
Also published as: CA2345390A1; WO2000017863A1; AU6060599A; JP2002525859A; TW468168B; IL141859A0; CN1319225A

Abstract

A magnetoresistive sensor (30) and a method of producing the magnetoresistive sensor (30) using electrochemical deposition are disclosed. An insulated substrate (11) is coated with a conductive coating (12) to ready the insulated substrate for electrochemical deposition, electroplating. The conductive coating (112) is latter patterned to prevent the short-circuiting of metallic regions. The conductive coating is electroplated with a metallic layer (131) and a magnetic alloy. The layers are etched to form four separate regions that are interconnected in a wheatstone bridge (473) configuration to form a sensor that can detect changes in an applied magnetic field (100). In some embodiments, the magnetic layers are separated by non-magnetic layers (114) to increase the sensitivity of the sensor. In other embodiments, pole piece elements are added to focus the magnetic field on two of the four regions.

Description

MAGNETORESISTIVE DEVICES, GIANT MAGNETORESISTIVE DEVICES AND METHODS POR MAKING SAME

BACKGROUND OF THE INVENTION

Field of Invention The present invention relates to magnetoresistive and giant magnetoresistive devices, and more particularly to magnetoresistive (MR) and giant magnetoresistive (GMR) devices and sensors fabricated using electrochemistry to deposit resistive material onto a conductive or partially conductive substrate and to methods for fabricating same. Description of Related Art

Magnetoresistive sensors are traditionally used to read data (memory) and when used in conjunction with a magnet, to monitor the position of moving objects. These sensors generally find use in a wide variety of applications, including navigational, ferromagnetic metal detection and location, position and proximity sensing, etc. Resistive elements may also be used as switches or relays integrated as part of, for example, tunable antennas and bipolar MOS type transistors to reduce source to drain current leakage and in other microelectronic applications requiring resistance variation.

A magnetoresistive or magnetoresistance ("MR") sensor is generally made up of electrically connected (or "bridged") regions of active material (resistors) that can detect changes in an applied magnetic field. These regions of active material have an electrical resistivity that changes as a function of both the magnitude and the direction of the magnetic field. In other words, the region of active material acts as a variable resistor when placed in a changing external magnetic field. The source of this magnetic field can be for example internal, originating from a region in close proximity on the same integrated circuit or external as for example, from the earth's magnetic field. The "sensitivity" of such resistors is measured as the ratio of the change in resistivity (ΔR) to the change in the magnetic field (ΔH) . Specifically, the magnetic field rotates the internal magnetization vector in the film, and the varying angle of this vector with the current flow affects the resistance. The sensitivity of a particular resistor depends on both the structural and chemical composition of the active material and, in the case of magnetoresistive devices, the value of the applied field. The region of active material can comprise several different layers, which are generally deposited using any number of different deposition techniques.

A typical material for use as the active layer (s) in MR devices is an alloy such as one containing, e.g., cobalt, nickel, copper, or iron. An example of such an appropriate alloy is one containing 78.5% nickel and 21.5% iron known generically and sold as PERMALLOY. The alloy PERMALLOY is useful for MR sensors because it has high magnetic permeability and electrical resistivity.

In sensor fabrication, a region (or regions) of active material is formed by depositing thin films of the various layers onto a substrate. Traditionally these thin films have been deposited by relatively expensive methods such as vacuum- based deposition, i.e., sputtering and molecular beam epitaxy and in some instances by electron beam (E-beam) or chemical vapor deposition (CVD) . Current commercially available MR sensors are fabricated by using electron beam, or sputtering techniques to deposit Permalloy as an active material on silicon chips. As a specific example, a prototypical commercial sensor is manufactured by sputtering to deposit layers of PERMALLOY (NiFe) onto a silicon substrate. In addition to their expense, resistors manufactured by CVD, sputtering, and MBE are difficult to manufacture in high volume because of the limits on the size of the substrate. Attempts in the past have been made at manufacturing resistors by other means . These have however resulted in sensors that are not sensitive nor reliable enough for modern applications. There are some commercially used less expensive deposition techniques, such as melt-spinning and ball-milling. However, these techniques are usually restricted to the production of heterogeneous alloys.

Giant Magnetoresitive ("GMR") sensors are made up of regions of active material and are less sensitive than MR sensors even though they exhibit larger total changes in resistance. Some GMR sensors are made up of magnetic layers separated by layers of diamagnetic or non-magnetic material while others are made of granular metals. The change in resistivity of these materials is attributed in part to conduction electrons moving across the non-magnetic layers and the accompanying spin-dependent scattering at or near the layer interfaces. It is believed that the in-plane resistance between two magnetic layers varies approximately as the cosine of the angle between the magnetization in the two layers. U.S. Patent No. 5,277,991 to Satomi et al . is directed to an example of such a GMR type material . In Satomi et al . magnetic and non-magnetic layers are deposited using a sputtering apparatus onto glass. This fabrication method has the advantage of using a large area substrate such as glass for producing high quantities of sensors, but is nonetheless still disadvantageous because it requires the use of an expensive manufacturing technique (sputtering) . Daughton, et al . describe a sensor made up of GMR Material in "Magnetic Field Sensors Using GMR Multilayer". The Daughton et al . sensor is fabricated on silicon wafers by using conventional integrated circuit processing (i.e. doping, masking, sputtering, etc.). Hence, these sensors are also manufactured using an expensive technique. Moreover, the manufacturing process is further limited, in that the relatively small area of the silicon wafer substrate, limits large-scale production. The article by . Schwarzacher and D.S. Lashmore, Giant Maαnetoresistance in Electrodeposited Films, IEEE Transactions on Magnetics, Vol.32, No. 4, July 1996, suggests that the use of electrochemical deposition (electrodeposition) would be considerably simpler and less expensive than other deposition techniques for laying down thin films. This article, which is herein incorporated by reference in its entirety, explains various techniques for electroplating thin metallic films.

In general, electrochemical deposition involves providing metal ions in a solution. The ions receive electrons from one of two electrodes (the cathode) and are thereby reduced to a solid form that deposits onto some type of substrate material. An example of a typical electrodeposition half reaction is shown below: Cu²⁺ _(aq) + 2 e- - Cu _(B)

If more than one species of metal ions is present in the solution (electrolyte) , it is possible to electrodeposit alloys as well as pure metals. Schwarzacher et al . produced GMR materials by electroplating thin metallic films onto copper plates. However, since the highly conducting copper substrates short-circuited the GMR materials during electrical transport measurements, it was necessary to include a relatively time consuming and impractical step of dissolving away the copper substrate before meaningful measurement could be made. In another article, M. Alper et al . , Giant

Macrnetoresistance in Electrodeposited Superlattices , Appl . Phys. Lett. 63 (15), 11 October 1993, the use of Electrodeposited GMR films as sensors for magnetic data storage is suggested but is also limited by the requirement of electrodepositing the thin films onto a copper substrate and the accompanying need to dissolve the copper substrate to avoid short circuiting the resistor.

Hence, despite its cost advantages, electrodeposition has not heretofore been used to fabricate MR or GMR sensors. As set forth above, the problems inherent in using this method to fabricate sensors have in the past been numbered and varied. In particular, as described above, the technique of electrodeposition requires that the material be deposited onto a conductive or partially conductive substrate, such as for example copper. Since the substrate must be conductive, it has heretofore been commercially impractical to form regions of active material thereon (resistors) without requiring the step of dissolving away the copper to avoid short circuiting the active resistive element.

Electroplating methods, as well as electrochemical treatments and plating apparatus for the electrodeposition of thin film alloys on a substrate, are well known. For example, Castellani et al , in U.S. Patent No. 4,103,756, issued July 25, 1978, teaches methods and apparatus for electroplating

Permalloy (NiFe) on a substrate. Electrodeposition has also been used to fabricate magnetic thin films, as for example, magnetic recording heads. Such recording heads are fabricated in U.S. Patent No. 4,756,816 to Liao et al . The CoFe thin films deposited in Liao et al . have acceptable permeability for recording purposes. However, these films are not magnetorestrictive and therefore cannot be used for sensor manufacture .

The use of electrodeposition in MR or GMR device or sensor fabrication to deposit active resistive material could enable the relatively inexpensive, rapid production of large quantities of devices or sensors on large area substrates such as glass. However, the necessity of having an appropriately conductive substrate versus the tendency for such a substrate to short circuit the resistive material has kept this technology from being commercially implemented. Additionally, the inability to deposit and permanently affix appropriate materials on otherwise suitable substrates has heretofore also prevented their use. Specifically, it has heretofore been virtually impossible to adhere thin films of electrodeposited metals such as copper onto large scale substrates such as planar glass that has been appropriately coated with a layer of conductive or partially conductive material to facilitate electrodeposition.

Furthermore, because both MR and GMR sensors must readily determine changes in the magnitude and direction of an applied magnetic field, it is advantageous to maximize the sensitivity of the regions of active material that are electrically interconnected to create the sensor. Such maximization has heretofore been difficult or impossible to obtain.

In sum, there is a need for magnetoresistors and giantmagnetoresistors and devices such as sensors made therefrom that: (1) can be fabricated in high volume and at low cost using electrodeposition techniques and (2) are sensitive and reliable enough for the demands of modern applications .

SUMMARY OF THE INVENTION The aforementioned and other drawbacks, problems, and limitations associated with the manufacture of conventional thin film resistors and sensors are overcome according to exemplary embodiments of the present invention. The present invention is based, in part, on using electrodeposition techniques to deposit regions of active (resistive) material onto a large area conductive (or partially conductive) substrate to produce reliable as well as low cost MR and GMR devices such as sensors.

The present invention also provides thin film magnetoresistive sensor (s) comprised of resistors having a line pattern wherein the width of the lines of magnetorestrictive material making up the resistors is maximized so as to enhance the sensitivity of the resulting sensor . In an exemplary embodiment, an insulated substrate is covered with a conductive coating. At least one region of magnetically active material is deposited on the substrate or conductive coating using electrodeposition. The region of active material is patterned, using photofabrication to form variable resistors having a line pattern. These resistors can detect changes in a magnetic field either resulting from an external source such as a remote magnet or internal source such as an adjacent magnetic source on the IC. The resistance of each resistor changes as a function of the applied field and its direction.

In another exemplary embodiment, high permeability material is electrochemically deposited to concentrate the magnetic flux delivered to a region of active material. Such pole pieces or magnetic flux concentrators are deposited as either part of the electrodeposition sequence or added at a later stage.

In another exemplary embodiment, magnetic layers separated by non-magnetic layers are alternately deposited onto a conductive substrate using electrochemical deposition techniques. The magnetic/non-magnetic layers are patterned to form a GMR resistor having increased magnitude of resistive change. For GMR sensors, the layer structures can be assembled in such a way to produce spin valve behavior. In some embodiments, the regions of active material are electrically connected to additional circuits (e.g., voltage sources, current sources, resistors, and capacitors) or even directly to a preamplifier chip to make up a MR or GMR device or sensor. The present invention also provides a process whereby magnetically active material is adherently electrodeposited onto a conductive substrate without electrically short circuiting the active material. Suitable substrates for use in the present invention include, but are not limited to indium tin oxide [ITO] coated glass, doped silicon, gallium-arsenide, germanium, or doped diamond.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features, and advantages of the present invention will be more readily understood upon reading the following detailed description in conjunction with the drawings in which:

Fig. 1 is a cross section of a magnetoresistive layer [MR] on ITO coated glass. Fig. 2 is an isolated MR resistor situated on a ITO coated glass substrate.

Fig. 3 is a block diagram illustrating the steps for deposition of magnetically active material [both MR and GMR] onto ITO coated glass. Fig. 4 is a cross section of a giant magnetoresistive [GMR] material electroplated onto ITO coated glass.

Fig. 5 is an isolated GMR resistor sitting on a planar ITO coated glass substrate.

Fig. 6 is a schematic top view of a complete magnetoresistive (MR) sensor made up of four (4) resistors and four (4) pole pieces.

Fig. 7 is an optical micrograph (17x magnification) of a sensor according to the present invention.

Fig. 8 is a schematic of a typical mask for photomasking the present invention sensors.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In a preferred embodiment a magnetoresistive device for detecting a change in a magnetic field in accordance with the present invention comprises an insulated substrate having at least one region of less than about 2000 A thickness of a conductive or partially conductive coating disposed thereon. It is preferable to limit the thickness of the conductive coating in order to prevent short circuiting problems associated with the application of resistive material onto conductive material.

The insulated substrate is preferably planar glass. Optical quality glass of the Glaverbel type is particularly suitable. However, other suitable materials for the substrate include, but are not limited to, a member selected from the group consisting of stainless steel, gallium arsenide and doped silicon.

The coating on the substrate is preferably selected from the group consisting of indium tin oxide (ITO) , indium oxide, and tin oxide and has a resistivity value of from about 10 ohms/square to about 100 ohms/square. Indium tin oxide is a particularly preferred material for use as the coating in this invention. There is at least one resistor region comprising at least one layer of from about 0.5 μm to about 2 μm of an electrodeposited metallic material disposed on each of the region (s) of conductive or partially conductive coating. This layer is intentionally kept at minimal thickness to prevent short circuiting of the resistive material deposited thereon. Suitable metals for use as the metallic material in this invention include, but are not limited to one or more of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof, with copper being especially preferred. The electrodeposited metallic material is at least substantially permanently affixed onto the coated substrate. It has heretofore been impossible to obtain this permanent adherance of the metallic material on a substrate such as ITO coated glass. There is a least one layer of from about 15 A to about

30 A of an electrodeposited ferromagnetic material disposed on the layer (s) of electrodeposited metallic material. Preferably there are from about 10 layers to about 100 layers of the ferromagnetic material. The ferromagnetic material is preferably comprised of a member selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof. Preferred ferromagnetic metals for use in this invention include iron and nickel and a preferred ferromagnetic alloy is permalloy.

Referring now to the drawings, Fig. 1 illustrates the aforedescribed device showing a region of magnetoresistive material disposed on a planar glass substrate having a partially conductive coating thereon. Substrate 11 can be of any shape, thickness, or size. Preferably, substrate 11 has a thickness of from about 0.8 μm to about 14 μm and is most preferably about 0.8 μm to about 2 μm in thickness .

As shown in Fig. 1, substrate 11 has conductive coating 12 disposed thereon. Conductive coating 12 is preferably a thin film or layer of a metal, oxide, or semiconductor. Thin metallic layer 13 is disposed on conductive coating 12. Ferromagnetic material layer 14 is disposed on thin metallic layer 13.

In a preferred embodiment, the deposition of metallic layer 13 and ferromagnetic material layer 14 is performed by electrochemical deposition. The deposition preferably takes place in an electrochemical cell (not shown) . A typical electrochemical cell for use in the present invention comprises a rectangular box made up of polypropylene. A "U" shaped magnet is affixed on the outside of the box and is of sufficient strength to provide a magnetic field of between 500-1000 gauss for MR material deposition. Uniformly distributed across the volume of the cell is a cathode affixed to one end of the cell and an anode at an opposite end of the cell exactly parallel to the cathode. A reference electrode is positioned in close proximity to a center of a cathode plate. A means of agitating the solution in a very uniform manner is provided. The solution is typically pumped through appropriate filters and there is a thermostat for controlling the temperature affixed to the cell. These resistors can be fabricated using electrodeposition cells and techniques known in the art .

Thin film 13 is a metallic material affixed onto the conductive coating. Thin film 13 preferably has a thickness of from about 10 nm to about 200 nm. The metallic material of thin film 13 is at least substantially permanently affixed to the conductive coating, as explained below. For purposes of this invention substantially permanently affixed is intended to mean that for all practical purposes the film does not readily peel off of the coating on the glass (substrate) . Copper is a particularly preferred material for use as the thin film affixed to the conductive coating.

The second thin film 14 is ferromagnetic material disposed on the metallic material 13 and as discussed above, has a preferred thickness of from about 50 nm to about 2000 nm.

Once the resistive material has been deposited onto the coated substrate, the resistor regions can be used as they are or processed further to form a magnetoresistive sensor. An MR sensor in accordance with the present invention comprises at least two electrically interconnected resistors on an insulated substrate having at least two regions of a conductive or partially conductive coating disposed thereon. Each of the resistors making up a sensor in accordance with the present invention comprises a magneto-resistive device as earlier described. The resistors are preferably electrically interconnected in a Wheatstone Bridge configuration.

The present invention MR sensor preferably further comprises at least one pole piece disposed on the coated substrate. The pole piece preferably comprises a region of electrodeposited pole piece material disposed on at least one region of the coated substrate. The region of electrodeposited pole piece material is preferably situated relative to the resistors such that the pole piece material acts to focus a magnetic field onto the resistors without shielding the resistors from same. In a preferred configuration the pole piece element focuses the magnetic field along its axis onto the resistors. Suitable material for use as pole piece material should preferably be a permeable material . Examples of such suitable pole piece material include, but are not limited to nickel-iron, cobalt- iron and combinations thereof. In a preferred embodiment an MR sensor in accordance with the present invention comprises at least one pole piece having a thickness of from about .5 μm to about 5 μm thick. The pole piece preferably comprises at least one layer of from about 0.5 μm to about 5 μm thick of metallic material selected from the group consisting of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof. The pole piece further comprises at least one layer of from about 15 A to about 30 A of an electrodeposited ferromagnetic material. The electrodeposited ferromagnetic material is preferably selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof and is disposed on the layer (s) of metallic material. Hence, in one embodiment the pole piece is comprised of the same material making up the reistors . Each of the resistors is configured in a linear pattern having a preferred line width of from about 15 μm to about 25 μm. In MR sensors according to the present invention, linear patterbs having the preferred line width maximize sensitivity of the sensor. Any given portion of the linear pattern should be spatially separated from another given portion by a distance of from about 2 μm to about 20 μm.

In a preferred embodiment the present MR sensor comprises four magnetoresistive regions (resistors) . Each of two of the four regions are preferably situated on the substrate at an angle that is about 90° relative to each of the other two of the four magnetoresistive regions (resistors) .

The resistor (s) are "patterned" and the pole pieces delineated using multiple steps of photofabrication. In the present invention, once the metallic layer and the ferromagnetic layer are electrodeposited onto conductive coating the resulting resistive material is photo masked with photo resist in a specific designed pattern such as that shown for exemplary purposes only in Fig. 8. Photo resist overlays a portion of the resistive material and protects it from subsequent etching steps. The conductive coating, the metallic layer and the ferrogmagnetic layer in any exposed region are etched away.

FIG. 6 illustrates a configuration of variable resistors in a sensor according to the present invention. Region 172,

272, 372, 472 are each one of four resistors, and regions 173,

273, 373, and 473 are pole pieces, which also serve as contact points. As shown in Fig. 6, variable resistors 172, 272, 372, and 472 are electrically interconnected through pole pieces 173, 273, 373, and 473 in a configuration commonly referred to as a Wheatstone Bridge. Additionally, contact points for connecting to an outside circuit can be spot welded or gold bonded onto the resistive material to connect with packaging case . During sensor operation, the contact points should be electrically connected across a voltage meter, voltage source, or capacitor (not shown) .

An MR sensor in accordance with the present invention can have a hysteresis measurement of about 1 gauss and a resistance measurement of from about 500 ohms to about 3000 ohms when measured using a Hall probe and applying a constant current of about 10 ma at a frequency of 1 KHz. Referring again to Fig. 7, the maximum sensitivity of this specially designed sensor is along arrow 101 direction. When the sensor is exposed to a changing magnetic field 100 in the direction of 101, the pole pieces 173, 273, 373 and 473 will align the magnetic flux along their axis and focus the field on resistors 172 and 372. For an MR sensor, when a changing magnetic field 100 in the direction of arrow 101 is applied, the resistor 172 and

372 have a electrical resistance that changes reversely proportional to the magnitude of the applied magnetic field 100. However, resistor 272 and 472 have a resistance that changes proportional to the magnitude of the applied magnetic field 100. This reverse MR response function combined with Wheatstone Bridge circuit increases the sensitivity in this MR sensor. In some applications, the pole pieces can be very thick to focus the magnetic field 100 to the resistors 172 and 372, the sensitivity of resistors 172 and 372 can be largely increased. In this case, the resistors 272 and 472 are mostly shielded from magnetic field 100 by the pole pieces 173, 273,

373 and 473.

In another embodiment, this invention is directed to a giant magnetoresistive device for detecting a change in a magnetic field. The device comprises an insulated substrate having at least one region of less than about 2000 A of a conductive or partially conductive coating disposed thereon. Preferably the insulated substrate is planar glass having a thickness of from about 0.8 μm to about 2.0 μm and the partially conductive coating is indium titanium oxide having a thickness of from about 0.2 μm to about 2.0 μm. The coating has a resistivity value of from about 10 ohms/square to about 100 ohms/square. Alternative coating materials include indium oxide and tin oxide and alternative substrate materials include stainless steel, gallium arsenide and doped silicon.

There is at least one resistor region on the coated substrate. The resistor region comprises at least one layer of from about 0.5 μm to about 1.0 μm of an electrodeposited metallic material disposed on each of the region (s) of conductive or partially conductive coating. The electrodeposited metallic material is at least substantially permanently affixed onto the coated substrate. There is at least one layer couple (multilayer) disposed on the layer (s) of electrodeposited metallic material . Suitable material for use as the metallic material includes chromium, platinum, gold, palladium, silver, copper, aluminum, titanium and alloys and combinations thereof, with copper being preferred. There are about 30 to about 600 layer couples and each layer couple comprises at least one layer and preferably from about 5 to about 15 layers of from about 20 A to about 30 A of electrodeposited ferromagnetic material in each of said at least one layer couple and at least one layer and preferably from about 3 to about 10 layers of from about 8 A to about 13 A of an electrodeposited non-ferromagnetic material. The number of layer couples, the number and thickness of the individual layers making up the couples will vary according to the materials being used and the ultimate use of the resistive material. For example, when depositing a cobalt/copper multilayer, it is preferred to have from about 30-100 couples of layer cobalt and one layer copper.

Suitable ferromagnetic material for use in the present GMR resistive device includes iron, nickel, copper, cobalt and alloys and combinations thereof. Example of such ferromagnetic alloys include Co-Ni-Cu, Ni-Cu, Ni-Fe, Co-Fe, Co-Ni, Co-Pt, Fe-Rh, with Co-Ni and Co-Ni-Cu being preferred.

The present embodiment also comprises a GMR sensor comprising an insulated substrate having at least two regions of less than about 2000 A thickness of a conductive or partially conductive coating disposed thereon. The coating has a resistivity value of from about 10 ohms/square to about 100 ohms/square. There are at least two and preferably four electrically interconnected GMR resistors configured substantially in accordance with the aforementioned description. At least two of the resistors are situated on the substrate. The electrical interconnection can be in a wheatstone bridge configuration. FIG. 4 illustrates a GMR resistor in accordance with the present invention. Substrate 111 can be of any shape, thickness, or size. As shown in Fig. 4 the substrate 111 has conductive coating 112 disposed thereon. As in MR sensor fabrication, conductive coating 112 is preferably a metal, an oxide, or a semiconductor. In a particularly preferred embodiment, the conductive coating is a thin film comprising indium tin oxide (ITO) . The conductive coating has a preferred resisitivity value of from about 10 ohms/square to about 100 ohms/square, and alternatively can be comprised of for example, but not limited to, stainless steel, gallium arsenide or doped silicon.

Like the MR sensors, the GMR sensors according to the present invention can further comprise a pole piece element . Likewise the pole piece element comprises a region of electrodeposited pole piece material disposed on at least one region of the coated substrate. The region of electrodeposited pole piece material is situated relative to the resistors such that the pole piece material acts to focus a magnetic field onto the resistors without shielding the resistors from same. Preferably the pole piece focuses the magnetic field along its axis onto the resistors.

Referring to Fig. 4, in a GMR resistor according to the present invention, a thin layer of metal 131 is disposed on the conductive coating 112 and has a preferred thickness of about 10 nm to about 200 nm. The metallic material of layer 131 is at least substantially permanently affixed to the conductive coating, as explained below. The metallic material should not be construed as being limited to copper, but is preferably selected from the group consisting of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof.

The active layer 114 is made of a number of alternative ferro-magnetic and non-magnetic layers. This multilayered film 114 is disposed directly onto the metallic layer 131. Each layer of the ferromagnetic material has a preferred thickness of from about 20 A to about 30 A, and preferably comprises a member of the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof. Suitable alloys for use as the ferromagnetic material include, but are not limited to a member of the group consisting of Co-Ni-Cu, Ni-Cu, Ni-Fe, Co-Fe, Co-Ni, Co-Pt, Fe-Rh, and combinations thereof (see table 1). Each of the layer (s) of non- ferromagnetic material has a preferred thickness of about from about 8 A to about 50 A. Suitable material for use as the non- ferromagnetic material includes, but is not limited to a member selected from the group consisting of copper, silver, platinum, palladium, titanium, chromium, rhodium and combinations thereof . In a preferred embodiment, the deposition of multilayer 114 is performed by electrochemical deposition. The relative thickness of each of these layers influences the sensitivity relative to the noise of the resultant sensor structure. For example, a copper layer having a thickness of about 12 A alternating with a cobalt layer having a thickness of about 20 A, results in a more sensitive but "noisier" (more hystereses) sensor than a copper layer having a thickness of about 24 A alternating with a cobalt layer having a thickness of about 20 A. The later would be less sensitive than the former and would typically respond linearly with the magnetic field.

Once layers 131 is electrodeposited onto the conductive coating, it is peeled off and layer 131 is replated on the conductive surface thereby substantially, permanently affixing this layer onto this substrate. A similar photo masking process as that described for the MR sensors above is carried out on the GMR sensor material .

Referring now to Fig. 3, in the case of a GMR sensor, a relatively thick (from about 1.0 μm to about 3.0 μm) pole piece would be necessary to shield the resistor 272 and 472 from magnetic field 100, because all four resistors 172, 272, 372 and 472 have the same response function to the magnetic field 100 (as shown in Fig. 6) .

In GMR sensors in accordance with the present invention resistors 272 and 472 can be replaced by constant resistors to balance the bridge circuit. In this case, the two balancing resistors 272 and 472 are optionally situated on a circuit board or integrated into a preamplifier circuit when such GMR sensors are used therewith. Referring now to Fig. 3 which schematically illustrates a process for fabricating a sensor in accordance with the present invention. Conductive material coated substrate 11 (as shown in Fig. 1) substrate is used for electrochemical deposition. Tthe size of substrate 11 is primarily limited only by the size of the electrochemical cell in which the electrodeposition step is performed.

In a preferred embodiment, the substrate comprises Glaverbel-type glass having a thickness that is about 1.1 μm and a coating thereon comprising indium tin oxide having a thickness from about .02μm to about 0.2 μm and a resistivity value of from about 10 to about 100 ohms per centimeter. Pre-cleaner 10 prepares substrate 11 and conductive coating 12 for electrochemical deposition thereon. Each substrate is cleaned using ultrasonic cleaning, de-ionized water, and an acid solution. Each substrate is attached to an electric contact and a copper loop.

A thin metallic layer 131 (shown in Fig. 4) is electrochemically deposited onto conductive coating 112. In a preferred embodiment, thin film depositor 20 comprises an electrochemical cell and a copper electrolyte. Thin film depositor 20 deposits at least one first layer (not shown) of from about 0.01 μm to about 0.2 μm of copper onto the conductive coating on the substrate. A film peeler (not shown) peels off the at least one first metal layer. Alternatively, the substrate is removed from the electrochemical cell and the first metal layer is peeled off by hand. The substrate is placed back in the cell and thin film depositor 20 deposits preferably from about 10 nm to about 200 nm of at least one second layer of copper onto the region on conductive coating 112 from which the first layer of copper is peeled so as to provide requisite electrical conductivity for further deposition. This second layer of copper is thereby substantially permanently affixed to the coated glass.

Magnetically active material depositor 30 deposits at least one thin film of magnetoresistive material 14 (shown in FIG. 1) onto the thin metallic layer 13. In order to make MR sensors, active material depositor 30 comprises an electrochemical cell and a solution for depositing a single magnetic element or magnetic alloy. In a preferred embodiment, the magnetic alloy comprises nickel and iron. Magnetoresistive material depositor 30 preferably deposits between 50nm and 2000nm of the magnetic alloy onto thin film 13. GMR deposition includes providing a substrate having a conductive coating thereon requires an additional step wherein a thin film depositor deposits a layer of non- ferromagnetic material alternatively with the ferromagnetic material being deposited. The present invention is also directed to a method for electrodepositing magnetoresistive material onto an insulated substrate and at least substantially permanently affixing same thereon. The method comprises the steps of providing an insulated substrate having a conductive or partially conductive coating to a thickness of from about 0.2 μm to about 2.0 μm thereon and electrodepositing at least one first layer of metallic material onto at least one region of the conductive or partially conductive coating. The conductive or partially conductive coating is selected from indium tin oxide (ITO) , indium oxide, and tin oxide, with indium tin oxide being preferred. The first layer has a preferred thickness of from about 0.5 μm to about 2.0 μm. Preferred material for use as the metallic material in the present invention includes, but is not limited to chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof, with copper being preferred.

The next step comprises removing the first layer of metallic material from conductive or partially conductive coating. After removing the first layer, a second layer of metallic material having a thickness of from about 0.5 μm to about 2.0 μm is electrodeposited onto the region (s) of conductive or partially conductive coating. At least one layer of magnetoresistive material is electrodeposited onto the second layer of metallic material. The preferred manner in which to remove the first layer of metallic material is by peeling it off the coated substrate. A magnetic field should preferably be provided during the electrodeposition steps, the value of the magnetic field is preferably from about 500 gauss to about 2 kilo-gauss.

In a further embodiment, the present invention is directed to a method for producing a sensor. The method comprises providing an insulated substrate having a conductive or partially conductive coating disposed thereon. A layer of from about 0.5 μm to about 2.0 μm of copper is at least substantially permanently affixed on the conductive or partially conductive coating. At least one layer of from about 15 A to about 30 A of ferromagnetic material is electrodeposited onto the layer of copper. At least one portion of the ferromagnetic material and the copper layer and conductive or partially conductive coating are etched away thereunder to thereby form at least two spatially separated regions of active material. Fig. 5 illustrates a GMR resistor in accordance with the present invention. Each of the regions of active material are then interconnected in an electrical bridge configuration.

In this method the substrate has a preferred thickness of from about 0.8 μm to about 2 μm. The conductive or partially conductive coating is selected from the group consisting of indium tin oxide (ITO) , indium oxide, and tin oxide, with indium tin oxide being preferred.

The step of electrodepositing at least one layer of ferromagnetic material onto the layer of copper comprises electrodepositing from about 10 mono-layers to about 100 layers of one of the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof. Nickel and the alloy permalloy are preferred.

The method can further comprise forming at least pole piece on said substrate by forming a region of electrodeposited pole piece material on the conductive or partially conductive coating. The region of electrodeposited pole piece material is situated such that it acts to focus a magnetic field being applied to the device onto the magnetoresistive region (s) without shielding it from same.

Preferably the pole piece element focuses the magnetic field along its axis onto the magnetoresistive region (s) . The pole piece is preferably permeable and selected from the group consisting of nickel-iron, cobalt-iron and combinations thereof .

In yet another embodiment, the present invention is directed to a method of making a giant magnetoresistive device for detecting a change in a magnetic field. The substrate and substrate coating are the same as those used in MR device fabrication. At least one resistor region is produced. The steps for depositing the GMR resistor comprise electrodepositing at least one layer of from about 0.5 μm to about 1.0 μm of a metallic material on each of the region of conductive or partially conductive coating on the substrate. The metallic material is at least substantially permanently affixed thereto. At least one layer couple is electrodeposited onto the at least substantially permanently affixed layer of electrodeposited metallic material. Each of the layer couple (s) comprises at least one layer of from about 20 A to about 30 A of a ferromagnetic material and at least one layer of from about 8 A to about 13 A of an non- ferromagnetic material. The ferromagnetic material is comprised of a member selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof. The alloys are selected from the group consisting of Co-Ni-Cu, Ni-Cu, Ni-Fe, Co-Fe, Co-Ni, Co-Pt, Fe-Rh, and combinations thereof, with Cu-Ni and Co-Ni-Cu being preferred. The non-magnetic material is preferably selected from copper, silver, platinum, palladium, titanium, chromium, rhodium and combinations thereof .

This method comprises electrodepositing from about 30 to about 100 layer couples onto the layer of electrodeposited metallic material. This method, like the one for fabricating the MR sensors can further comprise the step of forming at least one pole piece being situated relative to the giant magnetoresistive region such that the pole piece material acts to focus a magnetic field being applied to the device onto the giant magnetoresistive region (s) without shielding the region from same .

In order to fabricate a GMR resistor device and a sensor made therefrom according to the present invention, the active material is deposited in an electrochemical cell 30. An electrolyte solution of cobalt sulfamate, copper sulfate and boric acid.

In an alternative method for depositing pole-pieces, there is a multi-step photo masking process (1) . In this process photo resist will cover the whole surface of active layer and a window will be open only in pole pieces region 173, 273, 373 and 473 as shown in Fig. 6 to enable the deposition of additional pole piece layer through the windows. The pole piece depositor 50 deposits pole piece material on the active layer in the open regions. Pole piece depositor 50 can be the same or different electrochemical cell as active magnetic layer depositor with a solution for depositing a single magnetic element or magnetic alloy. The thickness of the pole piece layer varies from about 0.1 μm to 5 about μm. A photo resist cleaner cell 60 is used to remove the photo resist on the surface after pole piece deposition.

Photo masking process (2) 70 will mask the sample as the final pattern showed in Fig. 6.

The etcher 80 is responsible for removing regions between resistor lines and the region between the pole pieces as shown in Fig. 6. It is preferable to remove all conductive materials in the region mentioned, including active layer 14 for MR sensors and 114 for GMR sensors, conductive layer 13 and ITO layer 112. The enchant used in etcher 80 can be one or several in sequence to etch the metallic layers and ITO layer. If conductive coating 12 is not removed, variable resistor is not insulated from adjacent variable resistors (not shown) . When a variable resistor is electrically connected to additional circuits to form a sensor, the underlying ITO layer becomes a path for electrical current, the current in adjacent resistor lines will conduct laterally instead of along the path of lines making up the resistor. The reduced current that results along the intended path decreases the overall effectiveness of the sensor. The scriber 90 is responsible for making final cuts, if necessary, to the substrate 11. The scriber 90 should make whatever cuts are necessary to prepare substrate 11 and the resistors formed thereon for use in the ultimate application. Finally, the individual sensors will be packed in step

100.

Numerous variations or modifications of the disclosed invention will be evident to those skilled in the art. While the foregoing description makes reference to particular illustrative embodiments, this patent is intended to cover all variations or modifications that do not depart from the spirit and scope of the disclosed invention.

EXAMPLES

Example 1 - Electrodeposition and Photof brication for MR Sensor

1. Substrate :

Glass type: Glaverbel

Thickness: 1.1 μm

ITO Coating: 15 ohms/square 2 . Pre - clean steps : a) Samples preparation: the ITO glass is cut into

3.5" x 3.5" squares, electrical contact with a copper loop is made around a 3" diameter deposition window isolated from the electrolyte with electroplating tape. b) Pre-deposition cleaning: ultrasonic cleaning: 4 Oz/Gal Micro, 50°C, 3min rinse with deionized water: 50°C, 3 min dip into 2.5% H₂S0₄ etching for 1 min.

Rinse with D.I. water. 3. Copper deposition: a) electrolyte for copper conductive layer deposition: copper pyrophosphate strike solution: 333 ml/L; water: 666 ml/L; pH: 8.8 b) deposition condition :

Anode : Cu

Plating potential : potentiostatic deposition at -2.0V SCE (saturated calomel electrode) Temperature : ambient

Cathode and anode are kept parallel to achieve uniform film layer thickness c) copper layer deposition and bonding treatment:

50 nm of Cu are deposited on the prepared and cleaned ITO glass, the glass is then blown dry; scotch tape is used to remove the Cu film, the glass is etched with 2.5% H₂S0 and is rinsed with deionized water; the deposition procedure is repeated until a final thickness of the Cu layer on ITO glass is 45 nm as measured by coulombmeter . 4. Permalloy layer deposition:

Electrolyte :

Nickel sulfamate 315ml/L; Ascorbic Acid (antioxidant) 6g/L Iron sulfamate: 30 ml/L Boric acid: 30g/L

Saccharin: 2g/L Temperature: 50 °C pH : 2.0

Applied field: 600 gauss parallel to the film surface;

No stirring during deposition. The permalloy is electro-deposited to a layer thickness of 250 nm as measured by a coulometer

5. Photo-etching a) Cleaning: the sample is rinsed with Acetone,

Isopropanol and D.I. water while sample is placed on a spinner at low spin speed (-500 RPM) for a total of 60 second; then spin dried at 4000 RPM for 60 seconds. b) the sample is baked in an oven at 120°C for 15 minutes. The sample is allowed to cool for 3 minutes. c) photo-resist is spun on (Shipley, Inc. #1813): set time and speed as 6 sec at 700 RPM followed by 60 seconds at 4000RPM d) the sample is baked in an oven for 20 minutes at 120°C, then is allowed to cool for 3 minutes; e) the sample is masked, aligned and exposed to UV light at 15mV/cm² (setting on the exposure meter for 14 seconds) . f) developing: sample is placed back on spinner and developer is poured on at stopping mode for 60 seconds, the spin cycle is turned on, the sample is spun at low speed (500RPM) with developer and water for 10 extra seconds followed by water for 55 seconds. The sample is subjected to a high speed spin (4000RPM) for 1 minute to dry. g) the sample is hard baked at 120°C for 20 minutes.

6. Etching: a) solution: 1 part FeCl3 50g/l

1 part HCl 37% 50°C b) sample submerged for 10 seconds c) sample baked at 150°C for 5 minutes d) sample resubmerged in etchant for 2 more minutes e) sample rinsed with acetone to remove mask

7. Scribing:

The sample is cut into individual sensor elements using a commercial slicing saw. The glass is taped from the glass side and is cut using wheel 10PBM050A. Fig. 6 is an optical micrograph of a sensor made in accordance with this example .

Example 2 - GMR resistor and sensor fabrication 1. Substrate : Glass type: Glaverbel

Thickness: 1.1 μm

ITO Coating: 15 ohms/square

2. Pre-clean steps: a) Samples preparation: the ITO glass is cut into

3.5" x 3.5" squares, electrical contact with a copper loop is made around a 1" diameter deposition window isolated from the electrolyte with electroplating tape. b) Pre-deposition cleaning: ultrasonic cleaning: 4 Oz/Gal Micro, 50°C, 3min rinse with deionized water: 50°C, 3 min dip into 2.5% H₂S0₄ etching for 1 min. Rinse with D.I. water.

3. Copper deposition: a) electrolyte for copper conductive layer deposition: copper pyrophosphate strike solution: 333 ml/L; water: 666 ml/L; pH : 8.8 b) deposition condition:

Anode : Cu

Plating potential : potentiostatic deposition at -2.0V SCE (saturated calomel electrode) Temperature: ambient Cathode and anode are kept parallel to achieve uniform film layer thickness c) copper layer deposition and bonding treatment:

50 nm of Cu are deposited on the prepared and cleaned ITO glass, the glass is then blown dry; scotch tape is used to remove the Cu film, the glass is etched with 2.5% H₂S0₄ and is rinsed with deionized water; the deposition procedure is repeated until a final thickness of the Cu layer on ITO glass is 45 nm as measured by coulombmeter .

4. GMR multilayer deposition: Electrolyte : cobalt sulfamate 500 ml/L; copper sulfate: 2.947 g

Boric acid: 30g/L Water: 500ml

Temperature : ambient pH : 2.2 cobalt cathode charge potential -1.8V copper cathode charge potential -0.26V cobalt plated to 20 A, shut power wait 3 seconds copper plated to 9 A.

5. Photo-etching a) Cleaning: the sample is rinsed with Acetone, Isopropanol and D.I. water while sample is placed on a spinner at low spin speed (-500 RPM) for a total of 60 second; then spin dried at 4000 RPM for 60 seconds. b) the sample is baked in an oven at 120°C for 15 minutes. The sample is allowed to cool for 3 minutes. c) photo-resist is spun on (Shipley, Inc. #1813) : set time and speed as 6 sec at 700 RPM followed by

60 seconds at 4000RPM d) the sample is baked in an oven for 20 minutes at 120°C, then is allowed to cool for 3 minutes; e) the sample is masked, aligned and exposed to UV light at 15mV/cm² (setting on the exposure meter for 14 seconds) . f) developing: sample is placed back on spinner and developer is poured on at stopping mode for 60 seconds, the spin cycle is turned on, the sample is spun at low speed (500RPM) with developer and water for 10 extra seconds followed by water for 55 seconds. The sample is subjected to a high speed spin (4000RPM) for 1 minute to dry. g) the sample is hard baked at 120°C for 20 minutes.

6. Etching: a) solution :

1 part FeC13 50g/l 1 part HCl 37% 50°C b) sample submerged for 10 seconds c) sample baked at 150°C for 5 minutes d) sample resubmerged in etchant for 2 more minutes e) sample rinsed with acetone to remove mask 7. Scribing: The sample is cut into individual sensor elements using a commercial slicing saw. The glass is taped from the glass side and is cut using wheel 10PBM050A.

Many different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in this specification. To the contrary, the present invention is intended to cover various modifications and equivalent arrangements included with the spirit and scope of the claims. The following claims are to be accorded a broad interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

WHAT IS CLAIMED IS:

1. A magnetoresistive device for detecting a change in a magnetic field comprising: an insulated substrate having at least one region of less than about 2000 A thickness of a conductive or partially conductive coating disposed thereon, said coating having a resistivity value of from about 10 ohms/square to about 100 ohms/square; and at least one resistor region comprising: at least one layer of from about 0.5 μm to about 2 μm of an electrodeposited metallic material disposed on each of said at least one region of conductive or partially conductive coating, said electrodeposited metallic material being at least substantially permanently affixed thereto; and at least one layer of from about 15 A to about 30 A of an electrodeposited ferromagnetic material disposed on said at least one layer of electrodeposited metallic material.

2. A device in accordance with claim 1, wherein the insulated substrate is planar glass having a thickness of from about 0.8 μm to about 2 μm.

3. A device in accordance with claim 2, wherein the conductive or partially conductive coating is selected from the group consisting of indium tin oxide (ITO) , indium oxide, and tin oxide. 4. A device in accordance with claim 1, wherein the substrate is selected from the group consisting of stainless steel, gallium arsenide and doped silicon. 5. A device in accordance with claim 3 , wherein the partially conductive coating is indium tin oxide. 6. A device in accordance with claim 1, wherein the metallic material is selected from the group consisting of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof.

7. A device in accordance with claim 6, wherein the metallic material is copper.

8. A device in accordance with claim 1, wherein there are from about 10 layers to about 100 layers of the ferromagnetic material comprised of a member selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof.

9. A device in accordance with claim 7, wherein the ferromagnetic material comprises nickel. 10. A device in accordance with claim 8, wherein the ferromagnetic material comprises iron.

11. A device in accordance with claim 8, wherein the alloy comprises permalloy.

12. An MR sensor comprising: an insulated substrate having at least two regions of less than about 2000 A of a conductive or partially conductive coating disposed thereon, said coating having a resistivity value of from about 10 ohms/square to about 100 ohms/square; and at least two electrically interconnected resistors, wherein each of said at least two resistors comprises: at least one layer of from about .5 μm to about 2 μm of an electrodeposited metallic material disposed on each of said at least two regions of conductive or partially conductive coating, said electrodeposited metallic material being at least substantially permanently affixed thereto; and at least one layer of from about 15 A to about 30 A of an electrodeposited ferromagnetic material disposed on said metallic layer. 13. An MR sensor in accordance with claim 12, wherein each of said at least two regions is configured in a linear pattern having a line width of from about 15 μm to about 25 μm.

14. An MR sensor in accordance with claim 12, wherein the substrate is selected from the group consisting of planar glass, stainless steel, gallium arsenide and doped silicon.

15. An MR sensor in accordance with claim 12, wherein the partially conductive coating is selected from the group consisting of indium tin oxide (ITO) , indium oxide, and tin oxide .

16. An MR sensor in accordance with claim 15, wherein the insulated substrate is planar glass having a thickness of from about 0.8 μm to about 2 μm and the partially conductive coating is indium titanium oxide having a thickness of from about .2 μm to about 2 μm and a resistivity value of from about 10 ohms/square to about 100 ohms/square.

17. An MR sensor in accordance with claim 12, comprising four resistor regions, wherein each of two of said four resistor regions are situated on said substrate at an angle that is about 90° relative to each of the other two of said four magnetoresistive regions.

18. An MR sensor in accordance with claim 17, wherein the four resistors are electrically interconnected in a wheatstone bridge configuration.

19. An MR sensor in accordance with claim 12, wherein the metallic material is selected from the group consisting of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof.

20. An MR sensor in accordance with claim 19, wherein the metallic material is copper.

21. An MR sensor in accordance with claim 12, wherein there are from about 10 layers to about 100 layers of the ferromagnetic material comprised of a member selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof.

22. An MR sensor in accordance with claim 21, wherein the ferromagnetic material comprises nickel.

23. An MR sensor in accordance with claim 21, wherein the ferromagnetic material comprises iron.

24. An MR sensor in accordance with claim 21, wherein the alloy comprises permalloy. 25. An MR sensor in accordance with claim 12, further comprising at least one pole piece disposed on said substrate having said conductive or partially conductive coating disposed thereon.

26. An MR sensor in accordance with claim 25, wherein said at least one pole piece comprises a region of electrodeposited pole piece material disposed on at least one region of said at least two regions of conductive or partially conductive coating, said region of electrodeposited pole piece material being situated relative to said at least two resistors such that said region of electrodeposited pole piece material acts to focus a magnetic field onto said at least two resistors without shielding said at least two resistors from same.

27. An MR sensor in accordance with claim 26, wherein said at least one pole piece element focuses the magnetic field along its axis onto said at least two resistors.

28. An MR sensor in accordance with claim 25, wherein said at least one pole piece comprises permeable material selected from the group consisting of nickel -iron, cobalt -iron and combinations thereof. 29. An MR sensor in accordance with claim 25, wherein said at least one pole piece is from about .5 μm to about 5 μm thick and comprises at least one layer of from about 0.5 μm to about 5 μm thick of metallic material selected from the group consisting of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof; and at least one layer of from about 15 A to about 30 A of an electrodeposited ferromagnetic material selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof disposed on said at least one layer of metallic material .

30. An MR sensor in accordance with claim 12, wherein said sensor has a hysterisis measurement of about 1 gauss and a resistance measurement of from about 500 ohms to about 3000 ohms when measured using a Hall probe and applying a constant current of about 10 ma at a frequency of 1 KHz.

31. An MR sensor comprising: planar glass having at least two regions of less than about 2000 A of indium tin oxide coating disposed thereon, said coating having a resistivity value of from about 10 ohms/square to about 100 ohms/square; and at least two interconnected resistors, wherein each of said at least two resistors comprises: at least one layer of from about 0.5 μm to about 2 μm of electrodeposited copper disposed on one of said at least two regions of indium tin oxide coating, said electrodeposited copper being at least substantially permanently affixed thereto; and from about 10 layers to about 100 layers of electrodeposited permalloy disposed on said copper, each layer having a thickness of from about 15 A to about 30 A; and at least one pole piece comprising a region of electrodeposited pole piece material disposed on the at least one region of indium tin oxide coating, said region of electrodeposited pole piece material being situated relative to said at least two resistors such that said pole piece focuses a magnetic field along its axis onto said at least two resistors without shielding said at least two resistors from same .

32. An MR sensor in accordance with claim 31, wherein each of said at least two resistors is configured in a linear pattern having a line width of from about 15 μm to about 25 μm.

33. An MR sensor comprising: an insulated substrate having at least two electrically interconnected rectangular resistors disposed thereon, each of said at least two resistors comprising a linear pattern of less than 2000 A of a conductive or partially conductive coating having at least one layer of from about 0.5 μm to about 2 μm of an electrodeposited metallic material disposed thereon and at least substantially permanently affixed thereto and at least one layer of from about 15 A to about 30 A of a ferromagnetic material disposed on the metallic material wherein said linear pattern is comprised of a line width of from about 15 μm to about 25 μm.

34. An MR sensor in accordance with claim 33, wherein a given portion of said linear pattern is spatially separated from another given portion by a distance of from about 2 μm to about 20 μm.

35. A giant magnetoresistive device for detecting a change in a magnetic field comprising: an insulated substrate having at least one region of less than about 2000 A of a conductive or partially conductive coating disposed thereon, said coating having a resistivity value of from about 10 ohms/square to about 100 ohms/square; and at least one resistor region comprising: at least one layer of from about 0.5 μm to about 1.0 μm of an electrodeposited metallic material disposed on each of said at least one region of conductive or partially conductive coating, said electrodeposited metallic material being at least substantially permanently affixed thereto; and at least one layer couple disposed on said at least one layer of electrodeposited metallic material, each of said at least one layer couple comprising at least one layer of from about 20 A to about 30 A of an electrodeposited ferromagnetic material and at least one layer of from about 8 A to about 13 A of an electrodeposited non-ferromagnetic material.

36. A giant magnetoresistive device in accordance with claim 35, wherein the insulated substrate is planar glass having a thickness of from about 0.8 μm to about 2.0 μm.

37. A giant magnetoresistive device in accordance with claim 36, wherein the conductive or partially conductive coating is selected from the group consisting of indium tin oxide (ITO) , indium oxide, and tin oxide.

38. A giant magnetoresistive device in accordance with claim 35, wherein the substrate is selected from the group consisting of stainless steel, gallium arsenide and doped silicon.

39. A giant magnetoresistive device in accordance with claim 37, wherein the partially conductive coating is indium tin oxide . 40. A giant magnetoresistive device in accordance with claim 35, wherein the metallic material is selected from the group consisting of chromium, platinum, gold, palladium, silver, copper, aluminum, titanium and alloys and combinations thereof . 41. A giant magnetoresistive device in accordance with claim

40. wherein the metallic material is copper.

42. A giant magnetoresistive device in accordance with claim 35, wherein there are from about 30 to about 600 layer couples disposed on said layer of electrodeposited metallic material. 43. A giant magnetoresistive device in accordance with claim 35, wherein there are from about 5 to about 15 layers of electrodeposited ferromagnetic material in each of said at least one layer couple.

44. A giant magnetoresistive device in accordance with claim 35, wherein there are from about 3 to about 10 layers of electrodeposited non-ferromagnetic material in each of said at least one layer couple.

45. A giant magnetoresistive device in accordance with claim 35, wherein said ferromagnetic material is comprised of a member selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof.

46. A giant magnetoresistive device in accordance with claim 45, wherein said alloys are selected from the group consisting of Co-Ni-Cu, Ni-Cu, Ni-Fe, Co-Fe, Co-Ni, Co-Pt, Fe-Rh, and combinations thereof.

47. A GMR sensor comprising: an insulated substrate having at least two regions of less than about 2000 A thickness of a conductive or partially conductive coating disposed thereon, said coating having a resistivity value of from about 10 ohms/square to about 100 ohms/square; and at least two electrically interconnected resistors, wherein each of said at least two resistors comprises: at least one layer of from about 0.5 μm to about 1.0 μm of an electrodeposited metallic material disposed on each of said at least two regions of conductive or partially conductive coating, said electrodeposited metallic material being at least substantially permanently affixed thereto; and at least one layer couple comprising at least one layer of from about 20 A to about 30 A of an electrodeposited ferromagnetic material disposed on said metallic layer alternating with at least one layer of from about 20 A to about 30 A of an electrodeposited non-ferromagnetic material. 48. A GMR sensor in accordance with claim 47, wherein the substrate is selected from the group consisting of planar glass, stainless steel, gallium arsenide and doped silicon.

49. A GMR sensor in accordance with claim 47, wherein the partially conductive coating is selected from the group consisting of indium tin oxide (ITO), indium oxide, and tin oxide .

50. A GMR sensor in accordance with claim 48, wherein the insulated substrate is planar glass having a thickness of from about 0.8 μm to about 2.0 μm and the partially conductive coating is indium titanium oxide having a thickness of from about 0.2 μm to about 2.0 μm and a resistivity value of from about 10 ohms/square to about 100 ohms/square.

51. A GMR sensor in accordance with claim 47, comprising four magnetoresistive regions, wherein two of said four magnetoresistive regions are situated on said substrate.

52. A GMR sensor in accordance with claim 51, wherein the four resistors are electrically interconnected in a wheatstone bridge configuration. 53. A GMR sensor in accordance with claim 47, wherein the metallic material is selected from the group consisting of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof.

54. A GMR sensor in accordance with claim 53, wherein the metallic material is copper.

55. A GMR sensor in accordance with claim 47, wherein the non-ferromagnetic material is selected from the group consisting of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof. 56. A GMR sensor in accordance with claim 53, wherein the metallic material is copper.

57. A GMR sensor in accordance with claim 47, wherein there are from about 10 layers to about 100 layers of ferromagnetic material comprised of a member selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof.

58. A GMR sensor in accordance with claim 57, wherein the ferromagnetic material comprises nickel.

59. A GMR sensor in accordance with claim 57, wherein the ferromagnetic material comprises iron.

60. A GMR sensor in accordance with claim 57, wherein the alloy comprises permalloy.

61. A giant magnetoresistive device in accordance with claim 47, further comprising at least one pole piece disposed on said substrate having said conductive or partially conductive coating disposed thereon.

62. A giant magnetoresistive device in accordance with claim

61, wherein said at least one pole piece comprises a region of electrodeposited pole piece material disposed on at least one region of said at least two regions of conductive or partially conductive coating, said region of electrodeposited pole piece material being situated relative to said at least two resistors such that said region of electrodeposited pole piece material acts to focus a magnetic field onto said at least two resistors without shielding said at least two resistors from same .

63. A giant magnetoresistive device in accordance with claim

62, wherein said at least one pole piece element focuses the magnetic field along its axis onto said at least two resistors .

64. A giant magnetoresistive device in accordance with claim 61, wherein said at least one pole piece comprises permeable material selected from the group consisting of nickel-iron, cobalt-iron and combinations thereof.

65. A giant magnetoresistive device in accordance with claim 61, wherein said at least one pole piece comprises at least one layer having a thickness of from about 0.5 μm to about 1.0 μm of metallic material selected from the group consisting of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof; and at least one layer having a thickness of from about 20 A to about 30 A of electrodeposited ferromagnetic material selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof disposed on said at least one layer of metallic material .

66. A giant magnetoresistive device in accordance with claim 47, wherein said sensor has a hysterisis measurement of from about 2 gauss to about 50 gauss and a resistance measurement

38 of from about 50 kilo-ohms to about 2 kilo-ohms when measured using a Hall probe and applying a constant current of about 10 ma at a frequency of 1 KHz .

67. A GMR sensor comprising: planar glass having at least two regions of less than about 2000 A of indium tin oxide coating disposed thereon, said coating having a resistivity value of from about 10 ohms/square to about 100 ohms/square; and four electrically interconnected resistors, wherein at least two of each of said four resistors comprises: at least one layer of from about 0.5 μm to about 1.0 μm of electrodeposited copper disposed on each of said at least two regions of indium tin oxide coating, said electrodeposited copper being at least substantially permanently affixed thereto; and from about 10 to about 100 layers of from about 20 A to about 30 A of electrodeposited permalloy disposed on said copper; and at least one pole piece comprising a region of electrodeposited pole piece material disposed on at least one region of indium tin oxide coating, said region of electrodeposited pole piece material being situated relative to said at least two resistors such that said pole piece focuses a magnetic field along its axis onto said at least two resistors without shielding said at least two resistors from same .

68. A GMR sensor comprising: an insulated substrate having at least two electrically interconnected rectangular resistors disposed thereon, each of said at least two resistors comprising a linear pattern of less than 2000 A of a conductive or partially conductive coating having at least one layer of from about 0.5 μm to about 1.0 μm of an electrodeposited metallic material disposed thereon and at least substantially permanently affixed thereto and at least one layer of from about 20 A to about 30 A of a ferromagnetic material disposed on the metallic material.

69. A method for electrodepositing magnetoresistive material onto an insulated substrate and at least substantially permanently affixing same thereon, comprising the steps of: providing an insulated substrate having a conductive or partially conductive coating to a thickness of from about 0.2 μm to about 2.0 μm thereon; electrodepositing at least one first layer of metallic material onto at least one region of said conductive or partially conductive coating, said at least one first layer having a thickness of from about 0.5 μm to about 2.0 μm; removing said first layer of metallic material from said conductive or partially conductive coating; after removing said first layer, electrodepositing a second layer of metallic material having a thickness of from about 0.5 μm to about 2.0 μm onto said at least one region of conductive or partially conductive coating; and electrodepositing at least one layer of ferromagnetic material, each of said at least one layer having a thickness of from about, onto said second layer of metallic material.

70. A method in accordance with claim 69, wherein said step of removing said first layer of metallic material is done by peeling off same. 71. A method in accordance with claim 69, further comprising the step of providing a magnetic field environment for the electrodeposition steps.

72. A method in accordance with claim 71, wherein said magnetic field has a value of from about 500 gauss to about 2 kilo-gauss.

73. A method in accordance with claim 69, wherein said metallic material is selected from the group consisting of chromium, platinum, gold, palladium, silver, copper and alloys and combinations thereof.

74. A method in accordance with claim 73, wherein said metallic material is copper.

75. A method in accordance with claim 69, wherein said conductive or partially conductive coating on said insulated substrate is selected from the group consisting of consisting of indium tin oxide (ITO), indium oxide, and tin oxide.

76. A method in accordance with claim 75, wherein said conductive or partially conductive coating is indium tin oxide having a resisitivity value of from about 10 ohms/square to about 100 ohms/square.

77. A method in accordance with claim 69, wherein the insulated substrate is planar glass having a thickness of from about 0.8 μm to about 2.0 μm and the partially conductive coating is indium titanium oxide having a thickness of from about 0.2 μm to about 2.0 μm and a resistivity value of from about 10 ohms/square to about 100 ohms/square.

78. A method in accordance with claim 69, wherein the step of electrodepositing ferromagnetic material is performed from an electrolyte comprising at least one member of the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof.

79. A method in accordance with claim 69, wherein the at least one layer of magnetoresistive material includes nickel.

80. A method in accordance with claim 69, wherein the insulated substrate is glass.

81. A method in accordance with claim 69, wherein the conductive coating is indium tin oxide.

82. A method in accordance with claim 69, further comprising the step of depositing pole piece elements. 83. A method in accordance with claim 82, wherein the pole piece elements focus a magnetic field along the axis of the pole pieces.

84. A device for detecting a change in a magnetic field comprising four regions of copper on an insulated glass substrate having an indium tin oxide (ITO) conductive coating, wherein the four regions of magnetic material are connected in a wheatstone bridge configuration.

85. A method for producing a sensor comprising: providing an insulated substrate having a conductive or partially conductive coating disposed thereon; at least substantially permanently affixing a layer of from about 0.5 μm to about 2.0 μm of copper on the conductive or partially conductive coating; electrodepositing at least one layer of from about 15 A to about 30 A of ferromagnetic material onto the layer of copper; etching away at least one portion of the ferromagnetic material and the copper layer and conductive or partially conductive coating thereunder to thereby form at least two spatially separated regions of active material; and interconnecting each of said at least two regions of active material in an electrical bridge configuration.

86. A method in accordance with claim 85, wherein the substrate has a thickness of from about 0.8 μm to about 2 μm.

87. A method in accordance with claim 85, wherein the conductive or partially conductive coating is selected from the group consisting of indium tin oxide (ITO), indium oxide, and tin oxide. 88. A method in accordance with claim 85, wherein the partially conductive coating is indium tin oxide. 89. A method in accordance with claim 85, wherein the step of electrodepositing at least one layer of ferromagnetic material onto the layer of copper comprises electrodepositing from about 10 layers to about 100 layers of ferromagnetic material comprised of a member selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof .

90. A method in accordance with claim 89, wherein the ferromagnetic material comprises nickel.

91. A method in accordance with claim 89, wherein the alloy comprises permalloy. 92. A method in accordance with claim 85, further comprising forming at least pole piece on said substrate.

93. A method in accordance with claim 92, wherein forming said at least one pole piece comprises forming a region of electrodeposited pole piece material on said conductive or partially conductive coating , said region of electrodeposited pole piece material being situated such that said region of pole piece material acts to focus a magnetic field being applied to the device onto said at least one magnetoresistive region without shielding said at least one active region from same .

94. A method in accordance with claim 93, wherein said at least one pole piece element focuses the magnetic field along its axis onto said at least one active region.

95. A method in accordance with claim 93 , wherein said pole piece is permeable and selected from the group consisting of nickel-iron, cobalt-iron and combinations thereof.

96. A method of forming a giant magnetoresistive device for detecting a change in a magnetic field comprising: providing an insulated substrate having at least one region of less than about 2000 A of a conductive or partially conductive coating disposed thereon, said coating having a resistivity value of from about 10 ohms/square to about 100 ohms/square; and producing at least one resistor region comprising: at least one layer of from about 0.5 μm to about 1.0 μm of an electrodeposited metallic material disposed on each of said at least one region of conductive or partially conductive coating, said electrodeposited metallic material being at least substantially permanently affixed thereto; and at least one layer couple disposed on said at least one layer of electrodeposited metallic material, each of said at least one layer couple comprising at least one layer of from about 20 A to about 30 A of an electrodeposited ferromagnetic material and at least one layer of from about 8 A to about 13 A of an electrodeposited non-ferromagnetic material. 97. A method in accordance with claim 96, wherein the insulated substrate is planar glass having a thickness of from about 0.8 μm to about 2.0 μm. 98. A method in accordance with claim 96, wherein the conductive or partially conductive coating is selected from the group consisting of indium tin oxide (ITO) , indium oxide, and tin oxide.

99. A method in accordance with claim 96, wherein the substrate is selected from the group consisting of stainless steel, gallium arsenide and doped silicon.

100. A method in accordance with claim 98, wherein the partially conductive coating is indium tin oxide.

101. A method in accordance with claim 96, wherein the metallic material is selected from the group consisting of chromium, platinum, gold, palladium, silver, copper, aluminum, titanium and alloys and combinations thereof.

102. A method in accordance with claim 101, wherein the metallic material is copper. 103. A method in accordance with claim 96, wherein there are from about 30 to about 100 layer couples disposed on said layer of electrodeposited metallic material.

104. A method in accordance with claim 96, wherein said ferromagnetic material is comprised of a member selected from the group consisting of iron, nickel, copper, cobalt and alloys and combinations thereof.

105. A method in accordance with claim 104, wherein said alloys are selected from the group consisting of Co-Ni-Cu, Ni- Cu, Ni-Fe, Co-Fe, Co-Ni, Co-Pt, Fe-Rh, and combinations thereof .

106. A method in accordance with claim 105, wherein the ferromagnetic material comprises Co-Ni. 107. A method in accordance with claim 105, wherein the ferromagnetic material comprises Co-Ni-Cu.

108. A method in accordance with claim 96, wherein the non- ferromagnetic material comprises a member selected from the group consisting of copper, silver, platinum, palladium, titanium, chromium, rhodium and combinations thereof.

109. A method in accordance with claim 96, further comprising forming at least one pole piece disposed on said substrate.

110. A method in accordance with claim 109, wherein forming said at least one pole piece comprises forming a region of electrodeposited pole piece material disposed on said conductive or partially conductive coating or, said region of Electrodeposited pole piece material being situated relative to said at least one magnetoresistive region such that said region of pole piece material acts to focus a magnetic field being applied to the device onto said at least one magnetoresistive region without shielding said at least one magnetoresistive region from same.