JPS609183A - Magnetoresistance effect element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetoresistive element suitable for a magnetoresistive head used as a read-only head among magnetic heads.

[Background of the invention]

In recent years, the development of magnetoresistive heads using magnetoresistive elements has become active, but these magnetoresistive heads are susceptible to signal magnetic fields leaking from magnetic media such as magnetic disks or magnetic tapes. The resistance of the magnetoresistive element changes, and by detecting the change, information recorded on the magnetic medium can be read.

The basic structure of the above magnetoresistive element is shown in FIG. Here, 1 is a substrate, 2 is an insulating layer, 3 is a permalloy thin film, and 4 is a conductor. In this way, the magnetoresistive element is constructed of, for example, a permalloy thin film processed into a rectangular shape and has a large magnetoresistive effect. dependent. The permalloy thin film can generally be formed by an EB vapor deposition method, a resistance heating vapor deposition method, a sputtering method, or the like, but permalloy thin films formed by a vapor deposition method have conventionally been used. The reason for this is that the permalloy thin film formed by vapor deposition has excellent magnetoresistive properties. However, the vapor deposition method has the disadvantage that the composition of the formal film varies widely and it is difficult to obtain a film with constant characteristics, which greatly affects the fluctuations in the characteristics of the magnetoresistive element. On the other hand, permalloy thin films formed by sputtering using targets prepared under fire have little variation in composition and constant properties;
Due to the large amount of entrainment of impurity gas such as Ar gas, the magnetoresistive effect characteristics are extremely poor when the film thickness is 0.3 μm or less, as shown by the arrow in FIG.
When a magnetoresistive element is made using a permalloy thin film of m, the reproduction output is small and the output is divided depending on the strength of the magnetic field.

[Summary of the invention]

The present invention aims to eliminate the above-mentioned drawbacks of permalloy thin films of 0.3 μm or less produced by sputtering, and to provide a magnetoresistive element suitable for a magnetoresistive head. In the present invention, 10-
A permalloy thin film is formed by a sputtering method using a permalloy target melted and produced in a high vacuum of 5φorr or less. This provides a permalloy thin film with little variation in composition and good and consistent magnetoresistive properties.

The properties of the permalloy thin film used in the magnetoresistive element include a specific resistance ρ0 of 15 μΩm or more, and a specific resistance change rate Δρ/
It is necessary that ρ0 is 2.0% or more (Fig. 3,
(Indicated by a dashed line in FIG. 4).

Therefore, the conditions for producing the target used are also limited, but in the present invention, the above conditions can be satisfied by forming a permalloy thin film using a target produced in a high vacuum of 10 -5 Torr or less. In addition, in the present invention, the target composition has a Ni concentration of 75 to 9 Q wt%.
It is especially effective when

The present invention will be described in detail with reference to Examples below.

[Embodiments of the invention]

Example 1 Figure 3 shows the relationship between the degree of vacuum during the production of permalloy targets of various compositions and the specific resistance change rate Δρ/゛ρ0 in a permalloy thin film with a thickness of about 35 x m formed by sputtering using the target. FIG. Here, curve 5 is a target composition of 75wt%Ni 25wt%Fe
In this case, curve 6 shows the case of 81wt%Ni-19wt%Fe, and curve 7 shows the case of 9Qwt%Ni-10wt%Fe. According to this example, when the target composition is 75 wt% Ni, Δρ/ρ0 is 2 if the degree of vacuum during target fabrication is approximately 2×10″5 TOrr or less.
．． Reach 0chi or more. Still, if Δρ/ρ0 is other (7
In the case of a 90wt%Ni target, which provides a larger value overall than in the case of 5wt Ni and 81wtNi, the degree of vacuum at the time of target production is approximately 9 x 10-5To
If it is less than rr, Δρ/ρ0 reaches 2.0 chi or more.

Therefore, the degree of vacuum during target production is 10-5To
A value of rr or less is appropriate.

Figure 4 is a diagram that organizes the results of Figure 3, and is approximately 2
Rate of change in specific resistance between a permalloy thin film formed using a target produced in a vacuum of 10-' Torr (in the case of curve 8) and a permalloy thin film formed using a target produced in the atmosphere (in the case of curve 9) Δρ/ρ0
shows target composition dependence. According to this example, 1
It has been found that if a permalloy thin film is formed using a target having a Ni composition of 75 to 9 Qwt% produced on the 0-5 Torr level, a permalloy thin film with a specific resistance change rate Δρ/ρ0 of 20 inches or more can be obtained.

〔Effect of the invention〕

As is clear from the above examples, 10-”I'orr
75wt%Ni~90w produced by melting in the following high vacuum
If a permalloy thin film is formed by sputtering using a permalloy target having a composition of t%Ni, the rate of change in specific resistance of the permalloy thin film can be improved to the extent that it can be used in a magnetoresistive element. As a result, a permalloy thin film with little variation in composition and constant characteristics, which is an advantage of the sputtering method, can be used as a magnetoresistive element, and a magnetoresistive element with less variation in output can be realized.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the basic structure of a magnetoresistive element, and Figure 2 shows the relationship between the film thickness and specific resistance change rate of a permalloy thin film formed by sputtering using a target prepared in the atmosphere. FIG. 3 is a diagram showing the effects of the present invention, and FIG. 4 is a diagram showing the effects of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Insulating layer, 3... Permalloy thin film, 4... Conductor, 5... Target composition is 75wt
Relationship curve between degree of vacuum and specific resistance change rate in case of %Ni, 6
... Relationship curve between degree of vacuum and rate of change in specific resistance when the target composition is 81 wt% Ni, 7... Relationship curve between degree of vacuum and rate of change in specific resistance when target composition is 90 wt% Ni, 8 ...Relationship curve between Ni composition and specific resistance change rate when using a target made on a 10-5 Torr stand, 9...N when using a target made in the atmosphere
Relationship between i composition and rate of change in resistivity

Claims (1)

[Claims] 1. In a magnetoresistive element that reads a signal magnetic field from a magnetic recording medium using the magnetoresistive effect of a permalloy thin film, the permalloy thin film is produced by melting the permalloy thin film in a high vacuum of 10"5 Torr or less. A magnetoresistive element characterized in that it is formed by a sputtering method using a target. 2. The N1 composition of the sputtering target is 75 to 90W.
t%, and the permalloy thin film produced by sputtering is controlled to have a thickness of 0.02 to 0.3 μm.