JPH0321087A - Manufacturing method for laminated type magnetoresistance component - Google Patents

Abstract

PURPOSE:To prevent a change in the magnetic characteristics of a magnetic resistor thin film by forming a magnetic resistor layer on a substrate, and a block layer and a resist layer thereupon. CONSTITUTION:A magnetic resistor layer 1 is formed all over a substrate 2. Then, a block layer 8 designed to cut off plasma is formed on the surface of the magnetic resistor layer 1. A photosensitive organic layer 9 is coated on the surface of the block layer 8. When to the resist used for selective sputter etching of the magnetic resistor layer 1 is carbonized and removed by radiating reactive plasma ions, the plasma block layer 8 exists between the upper resist layer 9 and the lower magnetic resistor layer 1 preventing the reactive plasma from penetrating into the lower magnetic resistor layer 1. Therefore, the magnetic resistor layer 1 does not change its magnetoresistance characteristics due to the reactive plasma.

Description

[Detailed description of the invention] [Field of application in cliff industry] The present invention relates to a magnetoresistive element that detects an external magnetic field by using the so-called magnetoresistive effect in which electrical resistance changes according to changes in external magnetism, and in particular, The present invention relates to a method of manufacturing a type magnetoresistive element.

[Conventional technology]

FIG. 3 is a schematic diagram for explaining the operating principle of the laminated magnetoresistive element. The basic component of the laminated magnetoresistive element is a magnetoresistive thin film 1 patterned into an elongated shape. The magnetoresistive thin film 1 is flat on its thin film plane.
The electrical resistance changes depending on the intensity of the external magnetic field H applied across the longitudinal direction of the thin film.

This change in electrical resistance is detected as a potential difference between both ends by passing a current I along the longitudinal direction of the magnetoresistive thin film 1.

FIG. 4 shows the layer structure of a multilayer magnetoresistive element using the magnetoresistive thin film 1 shown in FIG. 3, and is a cross-sectional view taken along a plane perpendicular to the longitudinal direction of the magnetoresistive thin film. A magnetoresistive thin film 1 having a predetermined pattern is formed on the surface of an insulating substrate 2.
or is formed.

The surface of the magnetoresistive thin film 1 is covered with an insulating film 3,
An opening or window is formed in a part of the insulating film 3, and a part of the magnetoresistive thin film 1 is exposed. A conductive film 4 is formed on the surface of the insulating film 3 so as to fill the opening. The conductive film 4 is patterned into a predetermined shape and is electrically connected to the magnetoresistive thin film 1. This conductive film 4 is used to flow a current (2) along the longitudinal direction of the magnetoresistive thin film 1.

FIG. 5 is a perspective view showing an application example in which a multilayer magnetoresistive element is incorporated into a magnetic rotary encoder. A number of N poles and S poles corresponding to the number of output pulses of the encoder are alternately magnetized on the outer periphery of the rotary drum 6, and the laminated magnetoresistive element 5 is arranged adjacent to the outside of the rotary drum 6. Encoder 7
By rotating as shown by the arrow, the N-pole and STh magnetic fields passing through the multilayer magnetoresistive element 5 are detected and converted into electrical signals. Magnetic rotary encoders are used to control the speed and rotational angle phase of the rotating Ushiyama.

The sixth plot is a diagram showing the human output characteristics, that is, the magnetoelectric conversion characteristics, of the multilayer magnetoresistive element 5 shown in FIG. ε. The horizontal axis shows the change in the intensity of the external magnetic field H, and the vertical axis shows the change in the electrical resistance of the magnetoresistive thin film. As shown in FIG. 5, an external alternating current magnetic field H is applied to the magnetoresistive element 5 by the rotation of the quad drum 6, and an alternating current signal I is output in response to the change in the alternating magnetic field. The frequency of the alternating current signal (■) corresponds to the rotational speed of the encoder shaft, and its phase corresponds to the rotational angular position of the encoder shaft.

[Problem that the invention seeks to solve]

Conventionally, such laminated magnetoresistive elements have been fabricated using a resist film patterned using photolithography and chemical etching.

However, chemical etching is unsuitable for fine processing because it causes side etching of the end face of the thin film layer due to entrainment of etching components. The conventional manufacturing method has a problem in that it is not suitable for mass producing the minute and precise laminated magnetoresistive elements required by the market. In addition, conventionally, after etching the magnetoresistive thin film, ashing treatment was performed by plasma irradiation using oxygen ions to remove the resist film, but oxygen ions directly hit the magnetoresistive thin film made of permalloy. However, there was a problem in that its magnetic properties tended to be feminine.

[Means for solving problems]

In view of the problems of the conventional manufacturing method described above, an object of the present invention is to provide a manufacturing method suitable for mass production of fine and precise laminated magnetoresistive elements. In order to achieve this purpose,
According to the present invention, each stack is sequentially formed and etched using low temperature sputtering techniques and various thin film formation techniques. In particular, it is characterized by including a step for preventing the properties of the underlying magnetoresistive thin film from deteriorating when a resist layer used for sputter etching of the magnetoresistive thin film layer is ashed. FIG. 3 is a process diagram showing a manufacturing process of a multilayer magnetoresistive element according to the present invention.

In the step shown in FIG. 1A, a magnetoresistive layer 1 is formed on the entire surface of the base plate 2. Next, a shielding layer 8 for shielding plasma is formed on the surface of the magnetoresistive layer 1. A photosensitive organic resist layer 9 is then applied to the surface of the blocking layer 8.

In the step shown in FIG. 1B, the uppermost resist layer 9 is formed into a predetermined long fine pattern by exposure and development using photolithography.

In the step shown in FIG. 1C, the double layer of the blocking layer 8 and the magnetoresistive layer 1 existing outside the pattern of the resist layer 9 is selectively removed by sputter etching. Through this sputter etching process, the magnetoresistive layer 1 is formed precisely according to a predetermined pattern. be done.

In the step shown in FIG. 1D, the resist layer 9 is irradiated with reactive plasma and is incinerated and removed. At this time, since the surface of the magnetoresistive layer 1 is covered with the remaining blocking layer 8, the reactive plasma does not reach the underlying magnetoresistive layer 1 and is completely cut off.

Preferably, the treatment layer 8 is formed by a vacuum-deposited film of silicon dioxide. In addition, the vacuum-deposited silicon dioxide film has a thickness of 100 mm in order to completely prevent the invasion of reactive plasma particles.
It is preferable to evaporate on 0 or more people. Historically, the resist layer 9 is formed from a positive type organic photosensitive material, and the reactive plasma contains oxygen ions that react with the organic photosensitive +A material and ash it.

[For production]

According to the present invention, when the resist layer 9 used for selective sputter etching of the magnetoresistive layer is incinerated and removed by reactive plasma ion irradiation, one resist layer and the lower magnetoresistive layer are removed. A plasma blocking layer is inserted between 7I:
The reactive plasma does not penetrate into the underlying magnetoresistive layer. Therefore, the magnetoresistive properties of the magnetoresistive layer 1 are not changed by the reactive plasma.

In order to clarify the effect of the present invention, we investigated the feminization of magnetoresistive characteristics when a resist layer was formed directly on the surface of the magnetoresistive layer without intervening a blocking layer and an ashing treatment was performed. . Figure 2A is a diagram showing the magnetic resistance characteristics before the ashing process. The horizontal axis represents the external magnetic field, and the vertical axis represents the rate of change in resistance of the magnetoresistive layer. When the external magnetic field W is swept in both positive and negative directions, the resistance change rate has two peak values close to each other depending on the sweeping direction of the external magnetic field due to the hysteresis of the magnetoresistive layer.

FIG. 2B is a diagram showing the magnetoresistive characteristics after the resist layer is ashed by reactive ion plasma. As is clear from the figure, the two peak values fluctuate, indicating that the characteristics of the magnetoresistive layer have deteriorated due to the influence of the reactive plasma. In contrast, according to the present invention, the reactive plasma irradiation is completely folded by the intervening continuous folding layer, so the underlying magnetoresistive layer is not affected and the magnetic field remains as initially set during the manufacturing process. Maintaining resistance characteristics 41
is possible.

〔Example〕

Next, a method for manufacturing a bonded layer type magnetoresistive element according to the present invention will be explained in detail with reference to attached drawings A and J. 7A to 7J are process diagrams showing an embodiment of the manufacturing method according to the present invention.

In the step shown in 71dA, a silicon wafer commonly used in semiconductor manufacturing is used as the overboard 2. The surface of the wafer is previously covered with a thermally oxidized layer 10 of silicon dioxide. The thickness of the thermal oxidation layer 10 is approximately 1 μ. Laminated layers are sequentially formed over the entire surface of the cutting board 2 using electron beam vacuum evaporation technology. First, a base layer 11 is deposited. The base layer {l is made of, for example, silicon dioxide, and the thickness of the deposited film is, for example, 2000 mm. Next, a magnetoresistive layer 1 is deposited.

The magnetoresistive layer is made of permalloy, which is a ferromagnetic alloy of nickel and iron, for example. In particular, permalloy having a composition of 83 nickel and 17 iron has a little hysteresis in the magnetic 1 degree resistance effect. The permalloy deposition process requires 300 to 500 people to prepare a film. Magnetoresistive layer 1
A barrier layer 8 is deposited on the surface of the substrate. The blocking layer 8 is made of a vapor-deposited film of silicon dioxide, and the film thickness is approximately 100 mm.
There are 0 people. Since this silicon dioxide thin film is formed by vacuum evaporation, it has many pinholes and needs to be at least 1,000 mm thick in order to effectively block plasma particles.

However, if this film thickness is increased more than necessary, the subsequent sputter etching process will take a lot of time and will be unproductive.

A surface layer l2 is also formed on the barrier layer 8 by electron beam vacuum deposition. The surface layer 12 is provided to maintain adhesion to the resist layer, and is made of, for example, an alumina vapor deposited film. All of the laminated structures described above can be formed continuously in a batch process by electron beam vacuum evaporation.

In the step shown in FIG. 7B, a resist layer 9 is applied to the entire surface layer 12. The resist layer 9 is made of a photosensitive organic material, and is particularly preferably a positive type resist I film. The positive type has better patterning viscosity than the negative type, and is suitable for manufacturing precise and minute magnetoresistive elements using re-sputtering technology.

In the step shown in FIG. 7C, the resist layer 9 is exposed and developed using a mask having a predetermined pattern, and is formed into a long shape.

In the step shown in FIG. 7D, the portions of the stack that are not covered by the patterned resist layer 9 are selectively removed using a sputter etching technique.

Sputter etching uses spatter particles with excellent anisotropy to reduce the size of the laminated layer by its impact force.2. ) has extremely high etching accuracy and does not suffer from the side etching problem that occurs with chemical formulas.

FIG. 8 shows a sputtering device or dry etching device used in the manufacturing process according to the present invention. This device is equipped with a vacuum chamber 21, and has an inlet 22 for introducing gas into the interior and an exhaust port 23 for discharging the gas. The ceiling wall of the vacuum chamber 21 has an anode electrode 24 on its side, and a cathode electrode 2 is disposed inside the vacuum chamber 21 facing the anode electrode 24.
5?(liii)

The inside of the cathode electrode 25 is hollow, and cooling water is introduced through a cooling pipe 26. Further, a high frequency power source 28 is connected to the cathode 11 electrode 25 via a matching hook 27. In addition, a large number of substrates 2 to be processed are placed on the cathode electrode 25.

To perform the sputter etching shown in FIG. 7D, inert argon gas is introduced into the vacuum chamber 21 through the suction port 22. A high-frequency voltage is applied between the anode electrode 24 and the cathode electrode 25 to turn argon gas into plasma, which is then irradiated onto the substrate 2 at an accelerated rate.

The vacuum deposited stack is selectively removed by the bombardment of the plasma particles. This sputter etching process can be performed at low temperatures and will not adversely affect the permalloy magnetoresistive thin film, which is sensitive to temperature.

In the step shown in FIG. 7E, the resist layer left on the uppermost layer is ashed and removed. The ashing process is performed using a sputtering apparatus shown in FIG. The sputter etching of the vacuum-deposited stack and the ashing treatment of the resist layer 9 can be performed continuously by batch processing. Of course, it is also possible to perform the etching and ashing processing using separate devices. To carry out the ashing process, a reactive gas such as oxygen is introduced into the vacuum chamber 21 via the inlet 22 . A high frequency voltage is applied between the anode electrode 24 and the cathode electrode 25 to turn the introduced oxygen gas into plasma. The ionized oxygen is accelerated and collides with the surface of the resist layer 9. Since the resist layer 9 is composed of an organic material, it reacts with oxygen gas, is separated, and is incinerated and removed. This is a so-called reactive ion etching process. At this time, the oxygen ion particles are substantially completely blocked by the return force Im8 formed by silicon dioxide vapor deposition and desorption.
It never reaches the magnetoresistive layer 1 of ψ. Unfortunately, the magnetoresistive layer 1 is not affected by the reactive plasma particles, and the excellent magnetoresistive properties of vermalloy with little hysteresis are preserved.

Next, in the step shown in FIG. 7F, a first insulating film made of a silicon dioxide thin film is formed over the entire surface of the vacuum-deposited laminated layer and the window plate 2 formed in a predetermined pattern in the previous step using the Magne 1 Ron sputtering technique. Apply layer 13. This first insulating layer l3 has a film thickness of about 3 μm and can completely cover not only the surface of the vacuum-deposited stack but also its edges.

In the step shown in Figure 7G, the first insulating layer 13 is selectively treated by reactive plasma ion etching using tetrafluoromethane gas to form openings for electrical connections or contacts at predetermined locations. Ru. This opening etching is performed until the surface layer 12 and the blocking layer 8 are exposed, and a portion of the surface of the underlying magnetic layer 1 is exposed.

In the step shown in FIG. 7H, the substrate 2 is taken out from the sputtering apparatus and transferred to a vacuum evaporation apparatus. A conductive layer 14 is formed using an electron beam vacuum evaporation method so as to cover the surface of the first insulating layer 13 and the inside of the opening. The conductive layer 14 is made of metal aluminum, for example.

Next, as shown in FIG. 7I, the conductive layer 14 is selectively chemically etched using a phosphoric acid-based etching solution using a resist layer (not shown) formed by photolithography to remove unnecessary portions. . The finally remaining conductive layer l4 forms a wiring pattern for electrically connecting the magnetoresistive layer 1 to an external drive circuit.

13 14? Later, as shown in FIG. 7J, a second insulating layer 15 is formed to completely cover the conductive layer 14 by magnetron sputtering. The second insulating layer 15 is also made of a silicon dioxide glass film and has a thickness of approximately 5 μm, like the insulating layer 14 of '2-. The second insulating layer 15 is selectively etched using a hydrofluoric acid-based etching wave to form a window 16 at a predetermined position and expose a portion of the conductive layer 14. The exposed conductive portion 14 constitutes a bonding pad and is electrically connected to an external circuit using a thin gold wire.

〔Effect of the invention〕

As described above, according to the present invention, since the laminated magnetoresistive element is basically manufactured using sputter etching technology, the magnetoresistive thin film can be processed with fine precision. This has the effect of providing a compact and high-performance magnetic sensor.Furthermore, when performing the ashing process to remove the photosensitive organic resist used when sputter etching the magnetoresistive thin film, the upper resist film and the lower magnetic layer are removed. 1. Because a blocking layer is interposed between the antibody thin films, reactive plasma particles consisting of oxygen ions do not reach the magnetoresistive thin film and cause changes in its magnetic properties. This has the effect of stably preserving the solid H properties of the thin film.

[Brief explanation of the drawing]

1A to 1D are schematic process diagrams showing the manufacturing process of a multilayer magnetoresistive element according to the present invention, and FIG. 2A is a conventional multilayer magnetoresistive element before ashing treatment of the resist layer. FIG. 2B is a diagram showing the magnetic resistance characteristics after ashing treatment, FIG. 3 is a conceptual perspective view for explaining the operating principle of the magnetoresistive element, and FIG.
The figure is a cross-sectional view showing the layer structure of a conventional multilayer magnetoresistive element.
Fig. 5 is a perspective view showing an example in which a multilayer magnetic resistance element is applied to a magnetic rotary encoder, and Fig. 6 is a fi! Diagrams showing the input/output characteristics when an ILW type magnetic resistance element is applied to a rotary encoder, and FIGS. 7A to 7J are preferred implementations of the method for manufacturing a multilayer magnetoresistive element according to the present invention. A process diagram showing an example and FIG. 8 are schematic cross-sectional views showing the configuration of a 15 1 6 sputtering apparatus used in the manufacturing method according to the present invention.

Claims (1)

[Claims] 1. A method for manufacturing a laminated magnetoresistive element consisting of a substrate and a magnetoresistive layer having a predetermined pattern formed on the substrate, comprising the steps of: forming a magnetoresistive layer on the substrate surface; , forming a blocking layer for blocking plasma on the magnetoresistive layer; forming a resist layer having a predetermined pattern on the blocking layer; and sputter etching outside the pattern of the resist layer. The remaining blocking layer blocks reactive plasma from the underlying magnetoresistive layer, and the resist layer is incinerated and removed by irradiation with the reactive plasma. 1. A method for manufacturing a multilayer magnetoresistive element, comprising the steps of: 2. The manufacturing method according to claim 1, wherein the barrier layer is formed of a vacuum-deposited film of silicon dioxide. 3. The manufacturing method according to claim 2, wherein the vacuum-deposited silicon dioxide film is deposited to a thickness of 1000 Å or more. 4. The manufacturing method according to claim 1, wherein the resist layer is formed from an organic photosensitive material, and the reactive plasma contains oxygen ions that react with and incinerate the organic photosensitive material.