JP2580490Y2 - Exposure photomask for manufacturing magnetoresistive elements - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure photomask for manufacturing a magnetoresistive element comprising a ferromagnetic thin film formed on a substrate.

[0002]

2. Description of the Related Art Conventionally, a magnetoresistive element has been manufactured as follows. That is, as shown in FIG. 2, N 2 is first deposited on an insulating substrate 6 by vapor deposition or sputtering.
A ferromagnetic thin film such as iFe or NiCo is formed.
A large number of magnetoresistive elements 7 having a pattern as shown in FIG. 3 are formed using an exposure photomask having a meander-shaped element pattern 8 for each element as shown in FIG.

As shown in the side view of FIG. 4, the thickness of the ferromagnetic thin film formed on the substrate 6 varies depending on the position on the substrate, for example, the left end is thicker than the right end. The thickness of the magnetoresistive element 7 varies depending on the element.

[0004]

What determines the magnetic field sensitivity of the magnetoresistive element is the saturation magnetic field strength. The smaller the saturation magnetic field strength, the higher the sensitivity of the element. The saturation magnetic field intensity H _O is expressed by the following equation.

[0005] _{H O = H K + 4πM S} t / W , however, H _K: anisotropy field constant 4πM _S: saturation magnetization t: ferromagnetic thin thickness W: pattern width as can be seen from this equation, the saturation field strength H _O changes depending on the thickness t of the ferromagnetic thin film. Therefore, the magnetic field sensitivity of the magnetoresistive element changes depending on the thickness of the magnetoresistive element, and the resistance value of the magnetoresistive element also changes. That is, when the film thickness of the magnetoresistive element is different for each element, the sensitivity and the resistance value of the magnetoresistive element vary, and the magnetic characteristics of the elements are different for each element.

FIG. 4 shows the relationship between the magnetic field strength of the magnetoresistive element and the rate of change of the magnetoresistance. In the figure, the horizontal axis represents the magnetic field strength H, and the vertical axis represents the magnetoresistance change rate R ₀ / R. The characteristic 11 is a magnetic characteristic based on the design.
Reference numeral 3 denotes the magnetic characteristics when the film thickness of the element is smaller than the design value. As can be seen from the figure, the magnetoresistance change rate decreases as the element thickness decreases, and a magnetic field intensity larger than a design value is required to obtain a desired resistance change rate.

When the temperature rises, characteristics 11 and 13 change as characteristics 12 and 14, respectively, and the rate of change in resistance decreases as a whole. By the way, when a magnetoresistive element is used as a magnetoresistive sensor, for example, a change in resistance of the magnetoresistive element caused by a change in magnetic field strength is converted into a change in voltage, and the voltage is compared with a predetermined threshold voltage by a comparator or the like. To detect the magnetic field strength. In this case, if the threshold voltage is set to the level of 15 in FIG. 5, the magnetic characteristic 11 based on the design becomes the characteristic 12 at a high temperature.
It rises by six. On the other hand, in the case of the characteristic 13 having a small film thickness, the characteristic becomes the characteristic 14 at a high temperature, so that the width of the increase in the threshold magnetic field strength becomes the width 17 which is much larger than the width 16. That is, when the film thickness of the magnetoresistive element is smaller than the design value, the temperature characteristics of the magnetoresistive element deteriorate significantly.

An object of the present invention is to provide an exposure photomask for manufacturing a magnetoresistive element capable of suppressing variations in characteristics of the magnetoresistive element in order to solve such a problem.

[0009]

SUMMARY OF THE INVENTION The present invention is an exposure photomask for manufacturing a magnetoresistive element formed of a ferromagnetic thin film formed on a substrate, and is provided with a plurality of meander-shaped element patterns. In the above, the element pattern
Line width according to the thickness of the ferromagnetic thin film.
And a variation in characteristics of the magnetoresistive element is suppressed .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an exposure photomask for manufacturing a magnetoresistive element according to the present invention. This photomask 1
Has a large number of patterns 2 for forming a meandering element pattern for each magnetoresistive element on a ferromagnetic thin film formed on an insulating substrate.
Is divided into a section (1) at the left end of the mask 1, a section (2) at the center, and a section (3) at the right end. Then, in the element pattern of the section (1) corresponding to the left end where the thickness of the ferromagnetic thin film formed on the substrate is smaller than the design value, the line width L1 is wider than the design value as in pattern 3. I have. In the element pattern of the section (2) corresponding to the central portion having the film thickness substantially equal to the design value, as shown in the pattern 4, the line width L2
Is equal to the design value. On the other hand, in the element pattern of the section (3) corresponding to the right end where the film thickness is thicker than the design value, the line width L3 is smaller than the design value as in the pattern 5. However, the repetition period of these element patterns, that is, the width of one element pattern is the same in any section. Patterns 3 to 5 show a part of the element pattern.

By using such a photomask 1, the line width of the element pattern is changed in accordance with the film thickness of the ferromagnetic thin film, and the change in the saturation magnetic field intensity accompanying the change in the film thickness is corrected. Variations in magnetic field sensitivity due to variations in the film thickness of the magnetoresistive element, or variations in temperature characteristics of the magnetic field sensitivity can be suppressed. As a result, the manufacturing yield can be improved and the manufacturing cost can be further reduced. .

In this embodiment, the element pattern 2 is divided into three sections. However, the number of sections is further increased, and the line width is finely set in accordance with the film thickness distribution to further reduce the change in the saturation magnetic field intensity. It is also possible to correct accurately.

[0013]

As described above, the present invention is an exposure photomask for manufacturing a magnetoresistive element comprising a ferromagnetic thin film formed on a substrate, and has a plurality of meander-like element patterns. In a photomask, a line width of an element pattern is different depending on the element pattern. Therefore, by using the photomask of the present invention, the line width of the element pattern is changed in accordance with the thickness of the ferromagnetic thin film, and the change in the saturation magnetic field intensity accompanying the change in the film thickness is corrected. Variations in the magnetic field sensitivity due to variations in the film thickness of the element or variations in the temperature characteristics of the magnetic field sensitivity can be suppressed, and as a result, the manufacturing yield can be improved and the manufacturing cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an exposure photomask for manufacturing a magnetoresistive element according to the present invention.

FIG. 2 is a plan view showing a number of conventional magnetoresistance elements formed on a substrate.

FIG. 3 is a view showing a pattern of the magnetoresistive element of FIG. 2;

FIG. 4 is a side view showing a number of magnetoresistive elements formed on the substrate of FIG.

FIG. 5 is a graph showing the relationship between the magnetic field strength of the magnetoresistive element and the rate of change in magnetoresistance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exposure photomask 2 Element pattern 3-5 patterns

Claims (1)

(57) [Scope of request for utility model registration] An exposure photomask for manufacturing a magnetoresistive element formed of a ferromagnetic thin film formed on a substrate, wherein a photomask having a plurality of meander-like element patterns is provided. A film of the ferromagnetic thin film
Varying according to the thickness, the variation in the characteristics of the magnetoresistive element
An exposure photomask for manufacturing a magnetoresistive element, wherein the exposure mask is suppressed .