KR940004365B1 - Making method of electric resistor - Google Patents

Abstract

forming an alloy thin film on a substrate; forming a magnetic field sensing part by selective wet etching the alloy thin film; formin a magnetic focusing part by depositing an alloy thin film using high frequency magnetic sputtering; and coating organic resin, and then forming an insulating protection layer, thereby obtaining the maximum resistor variation rate.

Description

Manufacturing method of magnetoresistive element

1 is a schematic diagram of a magnetoresistive element.

2 is a cross-sectional view of a conventional magnetoresistive element structure.

3 is a cross-sectional view of a conventional magnetoresistive element structure.

4a is a basic structural diagram of a magnetoresistive element according to the present invention;

4b is a cross-sectional view of FIG. 4a.

5 is a manufacturing process diagram of a magnetoresistive element according to the present invention.

6 is a graph showing the rate of change of resistance in the prior art and the present invention according to the change of the magnetic field.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetoresistive element which realizes high sensitivity and low cost by forming a magnetic field concentrating portion on the same surface of a magnetic field sensing portion in a magnetoresistive element which is one of magnetic sensors.

In magnetic sensors, physical phenomena related to magnetic fields are widely used as operation principles, and Hall elements, Hall ICs, magnetoresistance (effect) elements, magnetic transistors, search coils, reed switches, SQUIDs, and magneto-optical magnets that use these effects proficiently Sensor and the like.

Magnetoresistance effect is a peculiar effect of a ferromagnetic material, which has an orientation effect according to the change in the magnetization direction of the magnetic material and a magnetic effect in which the resistance changes depending on the size of the magnetization.

Ferromagnetic magnetoresistance effect element using this is mainly Ni-Fe, Ni-Co alloys as a material and is widely used for position and rotation detection as a high reproducibility element according to the signal magnetic field.

Ferromagnetic magnetoresistance effects include floating magnetoresistance effect in which the resistance decreases linearly when the magnetic field is large, and resistance is anisotropically changed depending on the angle between the magnetization direction and the current direction.

The effect used for the ferromagnetic magnetoresistance effect is the latter anisotropic magnetoresistance effect, which is particularly excellent in low field strength. The structure is formed in the form of a bend line in the thin film for the purpose of miniaturization and high resistance of the device (see also FIG. 4A).

Such a device is typically manufactured by forming a thin film pattern 1 on a substrate as shown in FIG. When the current flows in the longitudinal direction of the thin film pattern 1 and an external magnetic field Hex is applied to the thin film pattern 1, a change in the magnetic resistance is generated according to the magnitude of the external magnetic field, which is converted into a voltage or a current and output.

At this time, the magnetic poles are generated on both sides of the pattern and the magnetic field in the opposite direction to the magnetization direction of the external magnetic field Hex is called a diamagnetic field H _d and the size is H _d = 4πMt / w (w: Width, t: thickness of the pattern, M: magnetization box).

Therefore, as the effective field H _eff = H _ex -H _d , the effective field is decreased as the diamagnetic field increases.

In order to improve the efficiency deterioration due to the semi-magnetic field, conventionally, the magnetic field sensing pattern 3 is formed on the substrate 1 at regular intervals, and a thin film-type high permeability magnetic material (Mn-Zn ferrite) is interposed therebetween. Type) 2 on the same plane to manufacture a magnetoresistive element (FIG. 2), or to form an insulating magnetic focusing body 3 'on the substrate 1 as shown in FIG. Next, a nonmagnetic insulating layer 4 was applied, and a ferromagnetic pattern 2 'was formed thereon to manufacture a magnetoresistive element.

However, it is difficult to make micromachining with a gap of 1 ~ 2㎛, and the manufacturing process of forming an insulating magnetic concentrator on a substrate and then forming a nonmagnetic insulating layer and a ferromagnetic pattern is complicated. Shows undesirable results.

Accordingly, an object of the present invention is to overcome the problems of the prior art, to increase the efficiency by reducing the semi-magnetic field in a simple manufacturing process, to provide a method of manufacturing a high sensitivity magnetoresistive element at low cost.

In order to achieve the above object, in the present invention, a magnetic flux concentrator is installed on both sides of the magnetic field concentrator to increase magnetic field sensing efficiency on the same surface (on a substrate) as the magnetic field sensing pattern, and the magnetic flux concentrating portion is formed of a high permeability metal magnetic thin film.

Materials of the magnetic field concentrating portion and the magnetic field sensing portion can be used as Ni-Co and Ni-Fe alloys, respectively.

The manufacturing process for the magnetoresistive element in the present invention uses a photo lithographic process (photo lithographic process), which is a process of forming a set pattern from a mask on a material layer on the wafer surface. It is composed.

The method of manufacturing the magnetoresistive element according to the present invention will be described in detail through the steps described below. (A) 82 wt% Ni and 18 wt% Fe alloy using a high frequency (RF) sputtering method on the substrate 1; A thin film (wafer) is formed to a thickness of 500 to 2000 mm 3 (Fig. 5a).

(b) The photoresist PR is coated with a uniform layer on the wafer surface (FIG. 5B).

(c) The wafer mask system is a mask aligner in which a patterned mask is placed on the surface of the photoresist by a photolithographic process (a process of setting a pattern of a mask directly on a wafer and through an iterative process) (Fig. 5a). Is exposed to an infrared light source, the PR of the exposed portion is cured and then PR is developed and rinsed and removed, and the unexposed PR portion forms a pattern as shown in FIG. 5C '.

(d) A Ni-Fe alloy thin film is formed by a wet etching method (FIG. 5d).

Dipping a wafer as shown in FIG. 5C 'into a hydrofluoric acid solution etches (removes) the Ni-Fe alloy thin film in the portion where the photoresist has been removed but does not affect the photoresist.

(e) Rinse the PR with acetone to remove it (Figure 5e).

(f) After coating the PR having a thickness of 1 탆 (FIG. 5f), only the magnetic field focusing portion 4 is removed again using the Lift-off method (FIG. 5f ').

(g) A 82 wt% Ni and 18 wt% Fe alloy thin film was manufactured to have a thickness of 1 μm only in the magnetic field sensing portion 2 ′ using the high frequency magnetic sputtering method (FIG. 5 g).

The thickness of the Ni—Fe alloy thin film is equal to the thickness of PR in the e stage.

(h) PR is removed with acetone or PR remover (FIG. 5h). As a result, the high magnetic permeability magnetic field concentrating portion 5 is formed of Ni-Fe alloy material on both sides.

(i) coating epoxy (6), which is a kind of organic resin, to prevent pin holes (Fig. 5i).

(j) Al ₂ O ₃ , SiO ₂ , AIN and the like are coated with a thickness of 200 to 500 kPa as the insulating protective film 7.

When the magnetoresistive element is manufactured through the above-described manufacturing process, a magnetic resistive part of a high permeability metal material (Ni-Fe alloy) is provided on both sides of the magnetic field sensing part to obtain a higher resistance change rate, thereby achieving a high sensitivity resistance element. .

6 shows the change rate of the resistance according to the change of the external magnetic field of the resistive elements. the results are as follow. The maximum value of the change rate of resistance in the case of no magnetic field concentrating part (1) was 1.5%, and in the case of the conventional device (2), that is, between the patterns using the magnetic field concentrating part of Mn-Zn or Ni-Zn ferrite (second). The maximum resistance change rate was 3.5% when the magnetic field converging portion was formed below the magnetic field sensing pattern (see FIG. 3).

In the case of forming the magnetic field sensing unit through the manufacturing process of the present invention (3), the maximum resistance change rate was 3%, but as a result, the device of the present invention obtained the maximum resistance change rate almost similar to that of the conventional device, The process is remarkably easy and the yields are excellent, as shown in Table 1, by more than 30%, resulting in significant advances in yield and manufacturing costs.

TABLE 1

Claims (5)

Forming an alloy thin film on the substrate; Uniformly coating the photoresist PR thereon; Forming a PR having the same pattern as the magnetic field sensing unit by a photomask process; Forming an alloy thin film having a magnetic field sensing portion pattern by wet etching; Forming a magnetic field sensing unit by pinning and removing PR with acetone or the like; PR is coated on the substrate on which the magnetic field sensing unit is formed to remove the PR at the position of the magnetic field concentrating part by a lift-off method, and then the high frequency magnetic sputtering method forms an alloy thin film at the magnetic field concentrating part with the same thickness as the PR to remove the remaining PR. Forming a part; Coating an organic protective film and then coating an insulating protective film; Method of manufacturing a magnetoresistive element, characterized in that consisting of. The method of manufacturing a magnetoresistive element according to claim 1, wherein the magnetic field focusing portions are formed on the same plane on both sides of the magnetic field sensing portion pattern at a predetermined interval. The method of manufacturing a magnetoresistive element according to claim 1, wherein the magnetic field focusing portion is Ni-Co or Ni-Fe alloy which is a high permeability metal magnetic material. The method of manufacturing a magnetoresistive element according to claim 1, wherein the magnetic field focusing portion has a thickness of 1 µm or more, a width of the magnetic field sensing pattern is 10 µm, and a thickness of 500 to 2000 GPa. The method of manufacturing a magnetoresistive element according to claim 2, wherein the Ni-Fe alloy has a composition of 82 wt% Ni and 18 wt% Fe.

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