JPS63310187A - Manufacture of ferromagnetic magneto resistance element - Google Patents

Abstract

PURPOSE:To improve the durability of a magnetoresistance element without reducing its output by covering the whole surfaces of a magnetic sensor and a wiring and a predetermined position of a terminal with an SiO2 film of 2-4mum thickness by means of sputtering. CONSTITUTION:A magnetic sensor 2, a wiring 3 and a terminal 4 of desired shapes and sizes are formed on a glass substrate 1, and the whole surfaces of the sensor 2 and the wiring 3 and a predetermined part of the terminal 4 are covered with an SiO2 layer or an SiON layer of 2-4mum thickness as a protective film 7 by means of an RF magnetron sputtering method. The SiO3 or SiON has a preferable contact with a ferromagnetic material of the sensor 2. Thus, the durability of an element can be enhanced under high temperature and high moisture environment. Further, the thickness of the film is thinner than the protective film of resin, the sensor 2 can be approached to a magnetic field to be detected, and no output is reduced due to the approach.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a ferromagnetic magnetoresistive element used for detecting a magnetic field.

[Prior Art] A conventional magnetoresistive element, as shown in FIG. Part) 2, a wiring part 3 and a terminal part 4 for external connection made of the same material as or a different material from the magnetically sensitive part are provided, and a resin layer 5 as a protective film is provided on the substrate 1. Magnetic sensing part 2, wiring part 3. Terminal section 4 and lead wire 10
It was set up to cover. When a resin layer is used as a protective film in this way, since resin generally has high moisture permeability, in order to ensure sufficient reliability of the element in a high temperature and high humidity environment, the resin layer 5 must be several hundred μm thick or more. It needs to be as thick as . For this reason, it has become impossible to bring the magnetic sensing section 2 and the magnetic field to be detected sufficiently close to each other, and a decrease in output is unavoidable, making it difficult to detect weak magnetic fields. For example, when detecting and controlling the rotational speed of a motor, it is not possible to bring the sensor part 2 close enough to the magnetized rotor of the motor, so the rotational speed of the motor is detected by detecting a weak magnetic field with a narrow magnetization pitch. - Could not be controlled.

FIG. 7 shows a cross-sectional view of another example of a conventional ferromagnetic magnetoresistive element. In this conventional example, the magnetic sensing part 2. A part of the wiring part 3 and the terminal part 4 is formed with a thickness of 5 μm by vacuum evaporation method.
Covered with a protective film 6 made of the above SiO or 5i02,
It is sealed with resin 8. This conventional example uses SiO or 5
Taking advantage of the fact that the in2 film has very low moisture permeability and can be made thinner than the resin protective layer 5 in the conventional example shown in FIG. 5, the distance between the sensor part 2 and the detected magnetic field is made sufficiently short. The aim is to maintain the reliability of the device in a high temperature, high humidity environment without causing a decrease in output. but,
Films produced by vacuum evaporation have poor coverage of stepped areas, so Si
The thickness of the O or 5i02 film must be 5 μm or more, and therefore cracks are likely to occur in the film.

A large number of ferromagnetic magnetoresistive elements are formed on a single substrate through a lithography process, but elements with cracks in SiO or 5i (hti) cannot be used. The yield of the product was poor.Furthermore, it took a lot of time to form a film with a thickness of 5 μm or more by vapor deposition, resulting in low productivity.

[Problems to be Solved by the Invention] As described above, with conventional ferromagnetic magnetoresistive elements, it is impossible to achieve both reliability of the element and proximity of a part of the sensor to the detected magnetic field. Ta. SUMMARY OF THE INVENTION An object of the present invention is to eliminate the conventional drawbacks and provide a ferromagnetic magnetoresistive element having a crack-free, thin, and highly durable protective film.

[Means for Solving the Problems] In order to achieve the above object, the present invention forms a magnetically sensitive part, a wiring part, and a terminal part with predetermined shapes and dimensions on an insulating substrate, and forms a magnetically sensitive part, a wiring part, and a terminal part on an insulating substrate. A Si film with a thickness of 2 to 4 μm is deposited on the entire surface of the terminal part and the required parts of the terminal part by sputtering.
It is characterized by forming an O□ layer or a 5iON layer.

[Function] According to the present invention, a protective film made of 5iON in which part of the oxygen of 5in2 or 5i02 is replaced with nitrogen is formed by a sputtering method. 5i02 and 5iON have good adhesion to the ferromagnetic material constituting the magnetically sensitive part, and can significantly improve the durability of the element under high temperature and high humidity conditions. Compared to a protective film made of resin, the film thickness is extremely thin, and the magnetic sensing part and the detected magnetic field can be brought close to each other, so that there is no reduction in output.

Furthermore, since it is formed by sputtering, it has better coverage of stepped portions than a protective film formed by vacuum evaporation, and reliability can be ensured with a thin film thickness, which greatly improves productivity and mass production.

Furthermore, S02 or 5iON@ by sputtering
An insulating inorganic thin film is applied on top using a coating method.

It is also possible to form a heat-resistant polymer thin film to increase the rubbing strength during mounting.

[Example code] The present invention will be described in detail below with reference to the drawings.

Example 1 FIG. 1 shows a cross-sectional view of an example of a ferromagnetic magnetoresistive element manufactured according to the present invention.

A magnetically sensitive part 2, a wiring part 3, and a terminal part 4 having a desired shape and nine dimensions were formed on a glass substrate 1. The material forming each of these parts may be any conventionally used material and is not limited to any particular material. These parts can be formed by sputtering, plating, or any other method.

Next, using RF magnetron sputtering method using 5i02 as a target, the magnetically sensitive part 2. An S'i 02 protective film 7 was formed to cover the entire surface of the wiring section 3 and a predetermined portion of the terminal section 4. Sputtering conditions are AY pressure 8X
1 (1-3 TOrr, frequency 13.56M). While cooling the substrate with water, Si
An O□ film was formed.

Next, a lead wire 10 was connected to the terminal portion 4, and finally the connecting portion was molded using an epoxy resin.

The relationship between the film thickness of the 5i02 film, durability time, and crack generation density of the device thus fabricated is shown in FIGS. 2 and 3, respectively. Here, the durability time is the time until the resistance value of the element increases significantly when a voltage of 5V is applied and a current test is performed in an environment of 85°C and 85% relative humidity.
The average value of 100 elements and its dispersion are shown. The value shown as 2000 hours in the figure shows no change after 2000 hours of testing and the test was discontinued. In addition, 5i
No durability tests were conducted on the elements with cracks in the 02 coating, and the data shown in FIG. 2 are all results for elements with no initial cracks.

The crack generation density is a value measured by microscopic observation of cracks generated in the 5i02 film, and FIG. 3 shows the average value and variation for 10 substrates.

As can be seen from FIGS. 2 and 3, when the thickness of the sputtered Sin film exceeds 4 μm, the density of cracks increases rapidly. On the other hand, if the thickness of the SiO□ sputtered film is less than 2 μm, the durability time will be significantly shortened.

Therefore, the optimal thickness of the 5in2 sputtered film is 2 to 4 μm.
It is.

The 5i(h film has good adhesion to the ferromagnetic thin film that constitutes the magnetically sensitive part, and the protective film formed by sputtering has excellent coverage of stepped parts, so it is suitable for films made by vacuum evaporation. The film thickness can be made thinner, preventing cracks from forming and ensuring high reliability.

FIG. 4 shows another embodiment of the invention. This embodiment has a structure in which a 5 in 2 film 7 formed by sputtering is further coated with an Alcolade insulating film 9 having a thickness of 1 to several μm. By creating a multilayer structure like this)
In addition to the moisture resistance of the element, it is also resistant to scratches on the surface of the magnetically sensitive part.
The mechanical strength can be improved. Mechanical strength can also be improved by forming a heat-resistant polymer thin film such as polyimide in place of the Alcolade film.

Protection 1 in Example 1 of Huo Yu! ! Changed to 72sio□, 5i
A 5iON layer 7 was formed in which part of the oxygen in n2 was replaced with nitrogen.

Magnetically sensitive parts were formed on the glass substrate in exactly the same manner as in Example 1.
A wiring part and a terminal part were formed.

Next, using Si as a target, ^r gas, 02 gas, and N
A 5iON protective film was formed by a reactive sputtering method (RF magnetron) in which two gases were introduced so as to cover the entire surface of the magnetically sensitive part and the wiring part, and a predetermined part of the terminal part. The sputtering conditions were: the pressure ratio of each gas was A, r:02:
N2=5:1:4, sputtering pressure 3x
1O-2Torr, frequency 13.56MH2, and while cooling the substrate with water, 5iO
A N film was formed.

Next, lead wires were connected to the terminal portions, and finally the connecting portions were molded with epoxy resin.

FIG. 5 shows the relationship between the film thickness and durability time of the 5iON film of the device thus fabricated. Here, the durability time is the time until the resistance of the element increases significantly when a voltage of 5μ is applied and a current test is performed in an environment of 85°C and 85% relative humidity, as in Example 1. , shows the average value of 100 elements and its dispersion. The value indicated as 2000 hours in the figure shows no change after 2000 hours of testing, and the test was discontinued.

In this case as well, as in Example 1, when the thickness of the 5iON sputtered film was less than 2 μm, the durability time was significantly shortened.

[Effects of the Invention] As explained above, according to the present invention, the magnetic sensing part and the entire surface of the wiring part of the ferromagnetic magnetoresistive element and the required parts of the terminal part are coated with a 5in2 film of 2 to 4 μm by sputtering. Therefore, there is an effect that the reliability and manufacturing yield of the device can be significantly improved without causing a decrease in output.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a ferromagnetic magnetoresistive element according to an embodiment of the present invention, Figure 2 is a diagram showing the relationship between durability time and 5i02 film thickness, and Figure 3 is a graph showing the relationship between the number of cracks and the 5in2 film thickness. FIG. 4 is a cross-sectional view of a ferromagnetic magnetoresistive element in another embodiment of the present invention. FIG. 5 is a diagram showing the relationship between durability time and 5iON film thickness. FIG. and FIG. 7 are cross-sectional views of conventional ferromagnetic magnetoresistive elements. DESCRIPTION OF SYMBOLS 1... Glass substrate, 2... Magnetically sensitive part, 3... Wiring part, 4... Terminal part, 5... Protective film (resin), 6... Protective film (evaporated SiO or 5iO2 ), 7...
・Protective film (sputtering SiO□ or 5iON),
8...Mold resin, 9...Alcolade coating film, lO... Lead wire. 8 Moichireto °Funtotsutsuji Figure 1 Figure 1 Effect of change Figure 4 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] A magnetically sensitive part, a wiring part, and a terminal part having predetermined shapes and dimensions are formed on an insulating substrate, and a film with a thickness of 2 to 20% is formed by sputtering on the entire surface of the magnetically sensitive part and wiring part, and at a required part of the terminal part. A method for manufacturing a ferromagnetic magnetoresistive element, characterized by forming a 4 μm SiO_2 layer or a SiON layer.