JPH0223681A - Magnetoresistance effect element - Google Patents

Abstract

PURPOSE:To acquire a magnetoresistance variation type element having a large magnetoresistance variation rate and high sensitivity by applying a multilayer film which is made by laminating a ferromagnetic thin film having magnetoresistance effect and a metal conductor thin film having a high electric conductivity alternately. CONSTITUTION:A non-magnetic substrate 1, and a ferro magnetic layer 2 having magnetoresistance effect and a metal conductor layer 3 of high electric conductivity which are laminated thereon alternately are included. Firstly, the ferro magnetic layer 2 is formed on the substrate 1, then the metal conductor layer 3 is formed, and the last layer is a metal conductor layer; however, characteristics of a magnetoresistance effect element are independent of the sequence of lamination. As for a material of the non-magnetic substrate 1, Si, Al2O3, TiC, SiC, a sintered body of Al2O3 and TiC, ferrite, etc., can be used. A ferro magnetic alloy such as Fe-Ni alloy and Co-Ni alloy or a material made by applying additive thereto can be used for the ferro magnetic layer 2. As for a material of the metal conductor layer 3, a metal having high electric conductivity such as Au, Ag, Cu and Al or a material made by applying additive thereto can be used.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a magnetic field sensor using magnetoresistive effect,
In particular, the present invention relates to a magnetoresistive element suitable for magnetic field detection sensors and magnetic heads.

(Prior Art) As is well known, magnetoresistive elements that utilize magnetoresistive effects have high sensitivity and can provide a relatively large output, and are therefore widely used as magnetic field sensors and magnetic heads. In such magnetic field sensors and magnetic heads, a DC magnetic field is applied as a bias in order to increase the sensitivity and approximate linear response. Conventionally, 2% for magnetoresistive elements
Permalloy alloy thin films exhibiting a rate of change in magnetoresistance of about 100% are widely used.

(Problem to be solved by the invention) However, the rate of change in magnetoresistance of permalloy alloy thin films is still insufficient for measuring weak magnetic fields. There was a problem that sufficient sensitivity could not be obtained in some cases.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a variable magnetoresistive element with a large magnetoresistive rate and high sensitivity.

(Means for Solving the Problems) In order to solve the above problems, the present invention uses a multilayer film in which ferromagnetic thin films having a magnetoresistive effect and metal conductor thin films with high electrical conductivity are alternately laminated.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a partial cross-sectional structural diagram showing an example of the magnetoresistive element of the present invention. It includes a non-magnetic substrate 1, ferromagnetic layers 2 having a magnetoresistive effect and metal conductor layers 3 having high electrical conductivity, which are alternately laminated on the non-magnetic substrate 1.

In FIG. 1, the ferromagnetic layer 2 is first formed on the substrate 1, then the metal conductor layer 3 is formed, and the last layer ends with the metal conductor layer. The properties do not depend on the stacking order of these layers.

The materials of the non-magnetic substrate 1 according to the present invention include glass, Si,
Al□03, TiC, a sintered body of 5iC1A1203 and TiC, ferrite, etc. can be used, and for the ferromagnetic layer 2, ferromagnetic alloys such as Fe-Ni alloy, Co-Ni alloy, or additives to these can be used. can be used with the addition of Further, as the material for the metal conductor layer 3 according to the present invention, metals with high electrical conductivity such as Au, Ag, Cu, A1, etc., or materials in which additives are added to these metals can be used.

The above ferromagnetic material and metal conductor material are evaporated using a vacuum evaporation device with two evaporation sources or a sputtering device with two targets, and the two evaporation source shutters are alternately opened and closed, or the substrate By passing the evaporation source alternately over two evaporation sources, two types of materials can be alternately laminated on the substrate, thereby producing the multilayer film structure of the present invention.

(Example) The details of the present invention will be explained below using Examples.

Multilayer film samples 1 to 6 in which ferromagnetic layers and metal conductor layers shown in Table 1 were alternately and continuously laminated by RF magnetron sputtering in Ar gas using two targets.
It was created. A sapphire substrate was used as the substrate, and the substrate temperature was 200°C. The film formation rate was 1 person/second, and the film thickness of each layer was controlled by changing the opening and closing time of the shutter.The sputtering power was 1.3W/am2, and the sputtering pressure was 5X10-
It was 3 Torr. Here, the thickness of the entire film is all 10
It remained constant at 0OA. When the magnetic properties of these samples were measured using a vibrating sample magnetometer, the anisotropic magnetic field was 100
e, and exhibited soft magnetic properties suitable for a magnetoresistive element.

The rate of change in magnetoresistance of these samples was measured by the four-terminal method in a rotating magnetic field of 1 kOe, and is summarized in Table 1. 1st
As is clear from the table, in a multilayer film made by laminating alternately ferromagnetic thin films and metal conductor thin films, the electron Multilayer film samples 7 to 12 in which ferromagnetic layers and metal conductor layers shown in Table 2 were alternately and continuously laminated were prepared by beam vacuum evaporation.

A glass substrate was used as the substrate, and the substrate temperature was 100°C. The film-forming speed was 1 second per person, and the film thickness of each layer was controlled by changing the opening and closing time of the shutter of each evaporation source.The degree of vacuum during evaporation was 5×10 Torr. Here, the thickness of the entire film was kept constant at 100 OA. When the magnetic properties of these samples were measured using a vibrating sample magnetometer, the anisotropic magnetic field was 100 e or less in all cases, indicating soft magnetic properties suitable for magnetoresistive elements.

The rate of change in magnetoresistance of these samples was measured by the four-terminal method in a rotating magnetic field of 1 kOe, and is summarized in Table 2. Second
As is clear from the table, the multilayer film in which ferromagnetic thin films and metal conductor thin films are alternately laminated is more than twice as thick as the conventional permalloy alloy thin film (effects of the invention). By having a multilayer structure in which ferromagnetic thin films with a magnetoresistive effect and metal conductor thin films with high electrical conductivity are alternately laminated on a nonmagnetic substrate, the magnetoresistive rate is large and the magnetoresistive change is highly sensitive. This has the effect that a type element can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing the structure of the magnetoresistive element of the present invention. DESCRIPTION OF SYMBOLS 1... Nonmagnetic substrate, 2... First ferromagnetic layer, 3...
・Second ferromagnetism

Claims (1)

[Claims] A magnetoresistive element comprising a multilayer film in which a ferromagnetic thin film having a magnetoresistive effect and a metal conductor thin film having high electrical conductivity are alternately laminated.