JP2008166633A - Method for manufacturing magnetic sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a conventional barber / pole structure, which is composed of four steps of forming an insulating layer, etching an insulating layer, forming a conductive material, and etching a conductive material. As the pre-process of each etching, it includes three processes of forming a photoresist layer, exposure, and development. Therefore, the manufacturing process is complicated, resulting in a decrease in yield, an increase in manufacturing time, and each process. There is a problem in that it is difficult to reduce the cost because the material cost for the process also increases.
A step of forming a first photoresist layer on a magnetoresistive element, a step of forming a second photoresist layer on the first photoresist layer, the first photoresist layer, and the above-mentioned A step of forming a second photoresist layer on the mask from exposure and development, a step of forming a conductive layer by sputtering or the like, and a step of removing the mask by lift-off to form a plurality of strips on the magnetoresistive effect element A conductive portion is formed.
[Selection] Figure 3

Description

  The present invention relates to a method of manufacturing a magnetic sensor device formed by a thin film.

  As a conventional method of forming a plurality of strip-shaped conductive portions (barber pole structure), an insulating layer is deposited on the element, a barber pole window is etched in the insulating layer, and an insulating layer Depositing a conductive material over and within the barber pole window and etching away the conductive material between the barber pole windows to form a barber pole (e.g., Patent Document 1).

  Special table 2004-536453 gazette

The method of forming the barber-pole structure disclosed in the above-mentioned patent document is composed of four steps of forming an insulating layer, etching an insulating layer, forming a conductive material, and etching a conductive material. Specifically, since the three steps of photoresist layer formation, exposure, and development are included as pre-processes for each etching, the manufacturing process is complicated, resulting in a decrease in yield and a reduction in manufacturing time. There is a problem that it is difficult to reduce the cost because the increase and the material cost for each process increase.
Also, since the dimensional accuracy of the conductive part (barber / pole structure) affects the performance of the manufactured magnetic sensor device, the barber / pole / window size is important in the conventional structure. There is a problem in that it is determined in a plurality of steps of two steps of “development of photoresist” and “etching of insulating layer”.

  The present invention has been made to solve the above-described problems, and is a magnetic sensor device formed of a thin film that has a simplified manufacturing process, reduced costs, and improved performance as a magnetic sensor device. It aims at obtaining a manufacturing method.

  A method of manufacturing a magnetic sensor device formed of a thin film according to the present invention includes a step of forming a first photoresist layer on a magnetoresistive effect element and a second photoresist layer on the first photoresist layer. A step of forming the first photoresist layer and the second photoresist layer on the mask from exposure and development, a step of forming a conductive layer by sputtering, and a step of removing the mask by lift-off. A plurality of strip-shaped conductive portions are formed on the magnetoresistive effect element.

  As described above, according to the present invention, the step of forming the first photoresist layer on the magnetoresistive element, the step of forming the second photoresist layer on the first photoresist layer, On the magnetoresistive effect element, a step of forming the first photoresist layer and the second photoresist layer on the mask from exposure and development, a step of forming a conductive layer by sputtering, and a step of removing the mask by lift-off. Since the plurality of strip-shaped conductive portions are formed, the manufacturing process is simplified, the cost can be reduced, and the accuracy as a magnetic sensor device is improved.

Embodiment 1 FIG.
As one embodiment of the present invention, a method for manufacturing a magnetic sensor device using the present invention will be described.
FIG. 1 shows a cross-sectional view after forming a photoresist layer during the manufacturing process of the magnetic sensor device according to the first embodiment of the present invention. In the figure, the magnetoresistive effect element 1 is formed on a silicon substrate 2 through a silicon thermal oxide layer 3 formed as an insulating layer. Although the silicon substrate 2 is used as the substrate on which the magnetoresistive element 1 is installed, the substrate is not limited to this as long as insulation is ensured and the surface has a smooth surface. For example, a silicon substrate having a nitride layer on the surface or a glass substrate may be used. The magnetoresistive effect element 1 is used as a magnetic sensor device in actual use, for example, in a thinned bridge structure, but the pattern forming process of the magnetoresistive effect element 1 is omitted. The magnetoresistive element 1 uses, for example, a thin film having a thickness of about 20 nm to 50 nm mainly composed of ferromagnetic nickel, iron, etc., but is not limited thereto. The silicon thermal oxide layer 3 is a layer for electrically insulating the silicon substrate 2 and the magnetoresistive element 1 and may be formed by CVD or the like, but it is known that the thermal oxide layer exhibits a good withstand voltage. It is desirable to use a thermal oxide layer. A first photoresist layer 4 and a second photoresist layer 5 are laminated on the magnetoresistive effect element 1. The first photoresist layer 4 and the second photoresist layer 5 are made of materials having different dissolution speeds during development in order to form an undercut shape to be described later. Alternatively, in order to form an undercut shape, which will be described later, a material having a different sensitivity of exposure during exposure may be used.

FIG. 2 shows a sectional view in which the mask portion 6 is formed during the manufacturing process of the magnetic sensor device according to the first embodiment of the present invention.
A mask portion 6 having an undercut shape is formed on the photoresist layer through a step of performing pattern transfer by exposure and a step of developing the photoresist layer with a developer. The width of the first opening 7 provided in the first photoresist layer 4 is formed larger than the width of the second opening 8 provided in the second photoresist layer 5. Therefore, the mask portion 6 formed as a remaining portion after the development process of the first photoresist layer 4 and the second photoresist layer 5 has an undercut shape. In FIG. 2, for simplification, the three mask portions 6 and the two openings are schematically shown at arbitrary intervals. However, in practice, the length of the thinned magnetoresistive effect element 1 and the magnetic sensor device are shown. It is determined by the performance, and is not limited to this.

FIG. 3 shows a cross-sectional view in which a conductive layer 9 is formed on the mask portion 6 shown in FIG. 2 during the manufacturing process of the magnetic sensor device according to the first embodiment of the present invention. As shown in the figure, a part of the conductive layer 9 is formed on the magnetoresistive effect element 1 through the openings 7 and 8.
The conductive layer 9 may be any material having electrical conductivity, such as aluminum, aluminum copper, and gold. The conductive layer 9 is formed by sputtering or the like. In order to improve adhesion, diffusion prevention, etc., the conductive layer 9 is not a single layer, but is preferably formed on or sandwiching chromium or titanium.

4 is a cross-sectional view in which the mask portion 6 shown in FIG. 3 and the conductive layer 9 formed on the mask portion 6 are removed by a lift-off process after the manufacturing process of the magnetic sensor device according to the first embodiment of the present invention is completed. It is shown.
After the lift-off process, the conductive layer 9 remaining on the magnetoresistive effect element 1 becomes the conductive portion 10. The width of the conductive portion 10 related to the performance as a magnetic sensor device described later is defined by the width of the opening 8. Therefore, the width of the conductive portion 10 is determined in one step of “photoresist development” for forming the opening 8.

  FIG. 5 is a diagram illustrating a configuration of one side of a bridge structure including the magnetoresistive effect element 1 having four thin lines, and is an explanatory diagram of a magnetic sensor device having a conductive portion 10. In the figure, the conductive portion 10 is provided with an inclination of 45 (deg) with respect to the thinned axial direction of the magnetoresistive effect element 1. Since the magnetic sensor device is used in a state where a current is applied in the direction shown in the figure, the conductive portion 10 inclines the direction of the current flowing on the surface of the magnetoresistive effect element 1 by 45 (deg) as can be seen from FIG. Is provided. The electric potentials are equal in each conductive part 10, and current flows perpendicularly to the conductive part 10. When the magnetoresistive element 1 that is a ferromagnetic material is magnetized in the axial direction, the angle θ formed by the magnetization direction and the current direction when the external magnetic field is zero can be set to 45 (deg).

  When the magnetic sensor device is formed with a bridge structure composed of the magnetoresistive effect elements 1 which are thinned on the four sides, the resistance of each of the magnetoresistive effect elements 1 on the four sides is the same, the balance is maintained, and the external magnetic field is zero. In this case, it is desirable that the bridge output is 0, that is, the offset is 0. In order for the resistances of the magnetoresistive effect elements 1 constituting the four sides to be the same, it is important that the uniform conductive portion 10 is formed in the manufacturing process, that is, the width of the conductive portion 10 is uniform.

  As described above, according to the first embodiment, the step of forming the first photoresist layer 4 on the magnetoresistive effect element 1 and the second photoresist layer 5 on the first photoresist layer 4 are performed. A step of forming the first photoresist layer 4 and the second photoresist layer 5 on the mask portion 6 from exposure and development, a step of forming the conductive layer 9 by sputtering, and the like. Since the plurality of conductive portions 10 having a strip shape are formed on the magnetoresistive effect element 1 by the step of removing the portion 6 by lift-off, the manufacturing process is simplified and the cost is reduced.

  Further, since the width of the conductive portion 10 is determined in one step of “development of photoresist” for forming the opening 8, there is an effect of improving the performance as a magnetic sensor device.

Embodiment 2. FIG.
FIG. 6 shows an insulating layer on the magnetoresistive effect element 1 and a plurality of strip-shaped conductive portions 10 on the magnetoresistive effect element 1 after completion of the manufacturing process of the magnetic sensor device according to the second embodiment of the present invention. 11 is a cross-sectional view in which 11 is formed.
The insulating layer 11 is preferably a material that is electrically insulative and that protects the underlying magnetoresistive effect element 1 and the conductive portion 10 from the external environment, including, but not limited to, a silicon oxide film and a silicon nitride film. Instead of a material, a resin material such as polyimide may be used. The insulating layer 11 is desirably a dense layer with good adhesion.
The second embodiment has a structure in which the insulating layer 11 is added to the first embodiment, and the description of the overlapping parts in other configurations is omitted.

  As described above, according to the second embodiment, since the insulating layer 11 is installed, it is possible to prevent contamination from the external environment and deterioration of the magnetoresistive effect element 1 and the conductive portion 10 and the like, and to improve measurement accuracy. Has the effect of stabilizing.

It is a 1st sectional view in the manufacturing process of the magnetic sensor device by Embodiment 1 of this invention. It is 2nd sectional drawing in the manufacturing process of the magnetic sensor device by Embodiment 1 of this invention. It is a 3rd sectional view in the manufacturing process of the magnetic sensor device by Embodiment 1 of this invention. It is sectional drawing which the manufacturing process of the magnetic sensor device by Embodiment 1 of this invention was completed. It is conductive part structure explanatory drawing of the magnetic sensor device by Embodiment 1 of this invention. It is sectional drawing which the manufacturing process of the magnetic sensor device by Embodiment 2 of this invention was completed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Magnetoresistive element, 2 Silicon substrate, 3 Silicon thermal oxide layer, 4 1st photoresist layer, 5 2nd photoresist layer, 6 Mask part, 7 1st opening part, 2nd opening part , 9 Conductive layer, 10 Conductive part, 11 Insulating layer

Claims (5)

Magnetoresistive effect element arranged on the installation substrate,
And a magnetic sensor device in which a plurality of strip-shaped conductive portions are formed on the magnetoresistive effect element,
A step of forming a first photoresist layer on the magnetoresistive effect element and a step of forming a second photoresist layer on the first photoresist layer as a conductive portion to be formed on the magnetoresistive effect element; Forming the first photoresist layer and the second photoresist layer on the mask from exposure and development;
Forming a conductive layer by sputtering or the like;
A method of manufacturing a magnetic sensor device, comprising forming the mask by a lift-off process.   The mask formed of the first photoresist layer and the second photoresist layer has an undercut shape having a larger opening in the first photoresist layer than the second photoresist layer. The method of manufacturing a magnetic sensor device according to claim 1.   3. The method of manufacturing a magnetic sensor device according to claim 2, wherein the first photoresist layer and the second photoresist layer are made of materials having different dissolution speeds during development.   3. The method of manufacturing a magnetic sensor device according to claim 2, wherein the first photoresist layer and the second photoresist layer are made of materials having different photosensitivity during exposure. Magnetoresistive effect element arranged on the installation substrate,
And a magnetic sensor in which a plurality of strip-shaped conductive portions are formed on the magnetoresistive effect element, wherein an insulating layer covering the magnetoresistive effect element and the conductive portion is formed by a process such as sputtering. A method for manufacturing a magnetic sensor device.

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