CN100587993C - Giant magnetoresistive magnetic sensor and preparation method thereof - Google Patents

Abstract

The invention discloses a giant magnetoresistive magnetic sensor and a preparation method thereof. The sensor comprises a substrate (1) and an insulating layer (2) thereon, a ferromagnetic layer (4) sandwiched with a conductive layer (5), in particular, the ferromagnetic layer (4) sandwiched with a conductive layer (5) is covered with a coil (3), and the coil (3) and the ferromagnetic layer (4) are both covered with an insulating layer (2); the method comprises the following steps: using a mask, photolithography or ion etching, DC magnetron sputtering, radio frequency magnetron sputtering or plasma enhanced chemical vapor deposition, and semiconductor thin film processing technology to engrave, sputter and generate a coil lower conductor, a lower insulating layer, a magnetoresistive sensor composed of a ferromagnetic layer, a conductive layer and a ferromagnetic layer, a middle insulating layer, a coil vertical conductor, a coil upper conductor and an upper insulating layer, and electrically connecting the coil lower conductor, the coil vertical conductor and the coil upper conductor, thereby obtaining a giant magnetoresistive magnetic sensor. The sensor has high precision and sensitivity and is easy to industrialize.

Description

Giant magnetoresistive magnetic sensor and preparation method thereof

technical field

The invention relates to a sensor and a manufacturing method, in particular to a giant magnetoresistive magnetic sensor and a manufacturing method thereof.

Background technique

The giant magnetoresistance effect is a new phenomenon discovered in the past 10 years. When a constant high-frequency current is passed through a material with a giant magnetic effect, a weak external magnetic field change can cause a significant change in the impedance of the material, and the change rate can be as high as 50%. Due to the excellent magnetic field sensitivity of the giant magnetoresistance material, the stability and reliability of the detection can still be maintained even without introducing any amplification equipment into the external electronic circuit. The characteristics and applying it to the weak magnetic field detector will greatly improve the accuracy and precision of direction detection. At present, people have made some attempts and efforts in order to obtain a magnetic sensor with a giant magnetoresistance effect, such as a "soft magnetic multilayer sensor" disclosed in the Chinese invention patent application publication CN 1694275A published on November 19, 2005. Magneto-sensing devices with film giant magneto-impedance effect". It intends to provide a magnetic sensor with giant magneto-impedance effect. The magnetic sensitive device is composed of a silicon substrate with a silicon dioxide layer, pins, a soft magnetic multilayer film with a meandering sandwich structure and a bias permanent magnet, wherein the pins are drawn from the copper layers at both ends of the multilayer film, and Set on the substrate, the soft magnetic multilayer film of the whole zigzag sandwich structure is located on the silicon substrate with a silicon dioxide layer, and the bias permanent magnet is pasted on the back of the magnetic sensitive device with epoxy glue. When in use, the giant magneto-impedance effect curve of the multilayer film is biased by the permanent magnet, so that the magnetic sensitive device works in the linear region. However, this magnetic sensitive device has disadvantages. First, it is difficult to make the magnetic field lines of the magnetic field emitted by the permanent magnet attached to the back of the magnetic sensitive device strictly parallel to the plane where the multilayer film is located, thereby reducing its response to the magnetic field. Sensitivity and test accuracy cannot guarantee the uniformity of performance and quality when it becomes a mass product; secondly, the increase in ambient or working temperature will easily soften the epoxy glue, causing the displacement of the permanent magnet, which in turn affects its Sensitivity and accuracy; again, harsh workplaces, such as in a shaking or vibrating working environment, can easily cause permanent magnets to fall off, resulting in loss of function; finally, as a permanent magnet that provides a bias magnetic field, once it is pasted on the magnetic After the back of the magnetic sensitive device is placed, the magnetic field strength cannot be adjusted, which greatly limits the use environment and scope of application of the magnetic sensitive device.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art, and provide a giant magnetoresistive magnetic sensor with high precision and sensitivity, stable quality, and easy industrial production and its preparation method.

The giant magnetoresistive magnetic sensor includes a substrate, an insulating layer thereon, and a ferromagnetic layer sandwiched with a conductive layer, especially a coil is sheathed on the ferromagnetic layer sandwiched with a conductive layer, and the coil and the ferromagnetic layer are covered with insulation.

As a further improvement of the giant magnetoresistive magnetic sensor, the coil is a micro solenoid formed by a sputtering process, and its length, width and height are respectively 20-2000 microns, 10-2000 microns and 10-100 microns; The winding direction of the coil is perpendicular to the current direction of the conductive layer; the substrate is a silicon wafer or a quartz wafer or a sapphire wafer or a silicon carbide wafer.

The preparation method of the giant magnetoresistive magnetic sensor includes the cleaning of the substrate and the mask carried out thereon, photolithography or ion etching, semiconductor thin film processing technology, especially it is completed according to the following steps: (a) first use the mask Die, photolithography or ion etching process is used to carve the array pattern of the coil lower layer wire on the substrate, and then use the DC magnetron sputtering process to sputter metal material on it to form the coil lower layer wire array; (b) prior to the substrate on the substrate The two ends of each wire of the coil lower layer wire array use a mask process, and then use a radio frequency magnetron sputtering process or a plasma enhanced chemical vapor deposition process to generate a lower insulating layer on the substrate covered with the coil lower layer wire array; (c ) Using a semiconductor thin film processing technology to generate a magnetoresistive sensor composed of a ferromagnetic layer, a conductive layer and a ferromagnetic layer on the lower insulating layer; (d) using a radio frequency magnetron sputtering process or a plasma enhanced chemical vapor deposition process on the covered layer A middle insulating layer is formed on the lower insulating layer of the magnetoresistive sensor, and at the same time, a mask process is used in conjunction with the process of generating the middle insulating layer to form the middle insulating layer at both ends of each wire of the coil lower layer wire array on the substrate. Generate hollow pillars; (e) use DC magnetron sputtering process to sputter metal material at the hollow pillars in the middle insulating layer to generate coil vertical wires; (f) first use mask, photolithography or ion etching process in the middle Carve the array pattern of the coil upper layer wires on the insulating layer, and then use the DC magnetron sputtering process to sputter metal materials on it to form the coil upper layer wire array, and make the two ends of each wire of the coil upper layer wire array respectively connected with the middle (g) using radio frequency magnetron sputtering process or plasma enhanced chemical vapor deposition process to generate an upper insulating layer on the middle insulating layer covered with the upper layer wire array of the coil, thereby making a giant Magneto-resistive magnetic sensor.

As a further improvement of the preparation method of the giant magnetoresistive magnetic sensor, the metal material used to generate the lower wire of the coil, the vertical wire of the coil and the upper wire of the coil by the DC magnetron sputtering process is metal gold or metal silver or metal copper or metal Nickel or its alloy; the width of the coil lower layer wire and the coil upper layer wire are both 0.5-1.5 microns, and the thickness is 0.5-1.5 microns; the lower insulating layer, the middle insulating layer and the upper insulating layer are all carbon dioxide Silicon layer, wherein the thickness of the lower insulating layer and the upper insulating layer are both 2-2.5 microns, and the thickness of the middle insulating layer is 8-9.5 microns; the ferromagnet in the ferromagnetic layer is amorphous or nanocrystalline iron Cobalt silicon boron (FeCoSiB) or cobalt silicon boron (CoSiB) or iron copper neodymium silicon boron (FeCuNbSiB), the thickness of which is 10-100nm; the conductor in the conductive layer is metal gold or metal silver or metal copper or metal Nickel or its alloy has a thickness of 10 to 100 nm.

Compared with the beneficial effects of the prior art, firstly, the coil placed outside the ferromagnetic layer sandwiched with the conductive layer can provide bias for the magnetoresistive sensor composed of the ferromagnetic layer, the conductive layer and the ferromagnetic layer. The magnetic field can make the magnetic force lines of the magnetic field emitted by it precisely parallel to the magnetoresistive sensor, and will not be affected by itself or the outside world to cause any relative displacement between it and the magnetoresistive sensor. At the same time, it is easy to adjust the coil current, which is convenient The intensity of the magnetic field emitted by it can be adjusted accordingly, so that the applicability of the magnetoresistive sensor can be greatly increased. Greatly improved the sensitivity of the magnetic resistance sensor to the magnetic field response and the accuracy of the test, greatly stabilized its performance and quality, and is extremely easy to industrialized production; second, after the magnetic sensor of the present invention that is made is tested, by the test As a result, the change curve of the resistance with the external magnetic field shows that the change rate of the magnetoresistance is close to 100%, showing a high giant magnetoresistance effect. When a certain bias magnetic field is pre-applied on it, if there is another The direction of the small external magnetic field is the same as the direction of the bias magnetic field, the magnetic resistance of the magnetic sensor of the present invention will increase, on the contrary, the magnetic resistance decreases, which proves that it has the performance of highly sensitive discrimination to the direction of the external magnetic field; third, the preparation method is scientific , reasonable, simple and convenient, with remarkable effect, easy to master, and convenient for industrialized implementation.

As a further embodiment of beneficial effects, one is that the coil is a micro solenoid formed by sputtering technology, and its length, width and height are 20-2000 microns, 10-2000 microns and 10-100 microns respectively, making it not only It has the characteristics of compact structure and small volume, and has the advantages of low power consumption and low production cost; second, the winding direction of the coil is perpendicular to the current direction of the conductive layer. In addition to being easy to adjust the coil, the magnetic field lines emitted by its magnetic field can In addition to being precisely parallel to the magnetoresistive sensor, the magnetic field lines emitted by the magnetic field and the magnetic field lines generated when the current in the conductive layer flows are perpendicular to each other. At this time, the interaction force between the two is the largest, so it can be used The smallest input obtains the greatest bias effect; the third is that the substrate is made of silicon wafer or quartz wafer or sapphire wafer or silicon carbide wafer, so that the source of substrate raw materials is wide and easy to obtain; the fourth is the width of the coil lower layer wire and the coil upper layer wire Both are selected as 0.5-1.5 microns, and the thickness is selected as 0.5-1.5 microns, which fully meets the needs of the flow rate of the coil when it is working; fifth, the lower insulating layer, the middle insulating layer and the upper insulating layer are all made of silicon dioxide. , and its thickness is only 2 to 9.5 microns, which not only meets the requirements of the insulation level, but also has the characteristics of low production cost.

Description of drawings

The preferred modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a kind of basic structural representation of the present invention;

Fig. 2 is the graph that the resistance that obtains after testing the magnetic sensor of the present invention that makes changes with external magnetic field, the condition during test is that temperature is 25 ℃, and drive current frequency is 1MHz, and the modulus coordinate in the figure is external magnetic field, The ordinate is the magnetoresistance. As can be seen from the test results, the rate of change of the magnetoresistance is close to 100%, showing a higher giant magnetoresistance effect; as shown in A place in the figure, when a certain bias magnetic field is pre-added on the magnetic sensor of the present invention, If there is another smaller external magnetic field with the same direction as the bias magnetic field, the magnetic resistance of the magnetic sensor of the present invention will increase; Under the action of the magnetic field, it has high sensitivity to distinguish the direction of the external magnetic field;

Fig. 3 is a process schematic diagram of the preparation method of the present invention.

Detailed ways

Referring to FIG. 1 , the giant magnetoresistive magnetic sensor is composed of an insulating layer 2 and a coil 3 placed on a substrate 1 , and a ferromagnetic layer 4 sandwiching a conductive layer 5 is set in the coil 3 . Wherein, the substrate 1 is a silicon wafer. The thickness of the ferromagnetic layer 4 is 10 nm, and the ferromagnet in the ferromagnetic layer 4 is made of amorphous FeCoSiB (FeCoSiB). The thickness of the conductive layer 5 is 10nm, and the conductor in the conductive layer 5 is metal copper. The coil 3 is a micro solenoid formed by a sputtering process, which is composed of a coil lower wire 31 obtained by a metal copper sputtering process, a coil vertical wire 32 and a coil upper layer wire 33, wherein the coil lower wire 31 The width of the wire 33 on the upper layer of the coil and the coil is 0.5 micron, and the thickness is 0.5 micron; the winding direction of the coil 3 is perpendicular to the current direction of the conductive layer 5, and its length, width and height are respectively 80 microns, 80 microns and 50 microns. The insulating layer 2 is a silicon dioxide layer, and the coil 3 and the ferromagnetic layer 4 are covered by the silicon dioxide layer; the silicon dioxide layer is composed of a lower insulating layer, a middle insulating layer and an upper insulating layer, wherein the lower Both the insulating layer and the upper insulating layer have a thickness of 2 microns, and the middle insulating layer has a thickness of 8 microns.

Referring to Fig. 2 and Fig. 3, the preparation method of giant magnetoresistive magnetic sensor is, at first make with conventional method or buy commercial metal gold, metal silver, metal copper, metal nickel and its alloy, silicon dioxide, Amorphous or nanocrystalline iron-cobalt-silicon-boron (FeCoSiB), cobalt-silicon-boron (CoSiB) and iron-copper-neodymium-silicon-boron (FeCuNbSiB) are prepared sequentially in the following steps: a) first use a mask, photolithography (or Ion etching) process engraves the array pattern of the coil lower layer wire 31 on the substrate, and then uses the DC magnetron sputtering process to sputter metal material metal copper on it to generate the coil lower layer wire as shown in Figure 3 (a) 31 array; wherein, the width of the wire 31 in the lower layer of the coil is 0.5 (could be 0.5-1.5) microns, and the thickness is 0.5 (could be 0.5-1.5) microns. b) Use a mask process at the two ends of each wire of the coil lower layer wire 31 array on the substrate, and then use radio frequency magnetron sputtering (or plasma enhanced chemical vapor deposition) technology to cover the coil lower layer wire 31 array A lower insulating layer is generated on the substrate; wherein, the lower insulating layer is a silicon dioxide layer with a thickness of 2 (can be 2 to 2.5) microns, and the lower insulating layer corresponds to the two ends of each wire of the coil lower layer wire 31 array A hollow column 30 as shown in Fig. 3(b) is left. c) Use semiconductor film processing technology to generate a magnetoresistive sensor composed of a ferromagnetic layer, a conductive layer and a ferromagnetic layer as shown in Figure 3 (b) on the lower insulating layer; wherein, the ferromagnet in the ferromagnetic layer Nanocrystalline iron-cobalt-silicon-boron (FeCoSiB) has a thickness of 10 (maybe 10-100) nm, and the conductor in the conductive layer is metallic copper with a thickness of 10 (maybe 10-100) nm. d) Use radio frequency magnetron sputtering (or plasma enhanced chemical vapor deposition) process to generate a middle insulating layer on the lower insulating layer covered with magnetoresistive sensors, and at the same time use a mask process to form a middle insulating layer during the process of generating the middle insulating layer A hollow column 30 as shown in Fig. 3 (c) is generated in the middle insulating layer at the two ends of each lead wire 31 array of the coil lower layer wire 31 array on the substrate; wherein, the middle insulating layer is a silicon dioxide layer, and the thickness It is 8 (can be 8-9.5) microns. e) Using DC magnetron sputtering process to sputter the metal material metal copper at the hollow column 30 in the middle insulating layer to form the coil vertical wire 32 as shown in FIG. 3( d ). f) Use a mask, photolithography (or ion etching) process to engrave the array pattern of the coil upper layer wire 33 on the middle insulating layer, and then use the DC magnetron sputtering process to sputter the metal material metal copper on it to form such as The coil upper layer wire 33 array shown in Fig. 3 (e) figure, and make the two ends of each wire of the coil upper layer wire 33 arrays be electrically connected with the coil vertical wire 32 in the middle insulating layer respectively; Wherein, the coil upper layer The wire 33 has a width of 0.5 (could be 0.5-1.5) microns and a thickness of 0.5 (could be 0.5-1.5) microns. g) Use radio frequency magnetron sputtering (or plasma enhanced chemical vapor deposition) process to generate an upper insulating layer on the middle insulating layer covered with the coil upper layer wire 33 array; wherein, the upper insulating layer is a silicon dioxide layer with a thickness of 2 (It can be 2 to 2.5) microns. Thus, the giant magnetoresistive magnetic sensor shown in Fig. 1 and Fig. 3(f) and the curve in Fig. 2 is obtained.

Respectively select metal gold or metal silver or metal nickel or its alloys, silicon dioxide, ferromagnets in the metal material, amorphous or nanocrystalline cobalt silicon boron (CoSiB) or iron copper neodymium silicon boron (FeCuNbSiB), repeat The above-mentioned preparation process also produces the giant magnetoresistive magnetic sensor as shown in Fig. 1 and Fig. 3(f) and the curve in Fig. 2 .

Apparently, those skilled in the art can make various changes and modifications to the giant magnetoresistive magnetic sensor and its preparation method of the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (6)

1. A giant magnetoresistive magnetic sensor comprising a substrate (1) and an insulating layer (2) thereon, a ferromagnetic layer (4) wrapped with a conductive layer (5), characterized in that: The ferromagnetic layer (4) wrapped with the conductive layer (5) is covered with a coil (3), and the coil (3) is a micro solenoid formed by a sputtering process, and its winding direction is perpendicular to The current direction of the conductive layer (5), wherein the coil (3) is formed by connecting the coil bottom wire (31), the coil vertical wire (32) and the coil upper wire (33), and the coil bottom wire (31) and the coil The width and thickness of the upper conductor (33) are 0.5 to 1.5 microns, and the length, width and height of the micro solenoid are 20 to 2000 microns, 10 to 2000 microns and 10 to 100 microns respectively; Both the coil (3) and the ferromagnetic layer (4) are covered by an insulating layer (2), and the insulating layer (2) is a silicon dioxide layer, which consists of a lower insulating layer, a middle insulating layer and an upper insulating layer, And the silicon dioxide layer is formed by radio frequency magnetron sputtering or plasma enhanced chemical vapor deposition process, and its thickness is 2-9.5 microns. 2. The giant magnetoresistive magnetic sensor according to claim 1, characterized in that the substrate (1) is a silicon wafer or a quartz wafer or a sapphire wafer or a silicon carbide wafer. 3. A preparation method for the giant magnetoresistive magnetic sensor as claimed in claim 1, comprising the cleaning of the substrate and the mask, photolithography or ion etching, and semiconductor thin film processing technology carried out thereon, characterized in It is done in the following steps: a. First, use a mask, photolithography or ion etching process to engrave the array pattern of the coil's lower layer wires on the substrate, and then use the DC magnetron sputtering process to sputter metal materials on it to generate the coil's lower layer wire array; b. Use a mask process at both ends of each wire of the coil lower wire array on the substrate, and then use a radio frequency magnetron sputtering process or a plasma enhanced chemical vapor deposition process on the substrate covered with the coil lower wire array Generating the lower insulating layer; c. A magnetoresistive sensor composed of a ferromagnetic layer, a conductive layer and a ferromagnetic layer is formed on the lower insulating layer by using a semiconductor thin film processing technology; d. Use a radio frequency magnetron sputtering process or a plasma enhanced chemical vapor deposition process to form a middle insulating layer on the lower insulating layer covered with a magnetoresistive sensor. A hollow column is formed in the middle insulating layer at the two ends of each wire of the coil lower layer wire array on the chip; e. Use DC magnetron sputtering process to sputter metal material at the hollow column in the middle insulating layer to generate coil vertical wires; f. First, use a mask, photolithography or ion etching process to engrave the array pattern of the upper layer wires of the coil on the middle insulating layer, and then use the DC magnetron sputtering process to sputter metal materials on it to generate an array of upper layer wires of the coil, and The two ends of each wire in the coil upper layer wire array are respectively electrically connected to the vertical wires of the coil in the middle insulating layer; g. Using radio frequency magnetron sputtering process or plasma enhanced chemical vapor deposition process to form an upper insulating layer on the middle insulating layer covered with the upper wire array of the coil, thereby making a giant magnetoresistive magnetic sensor. 4. The method for preparing a giant magnetoresistive magnetic sensor according to claim 3, characterized in that the metal material of the coil lower wire, the coil vertical wire and the coil upper wire is metal gold or metal silver using a DC magnetron sputtering process Or metal copper or metal nickel or alloys of the above metals. 5. The preparation method of giant magnetoresistive magnetic sensor according to claim 3, characterized in that the ferromagnet in the ferromagnetic layer is amorphous or nanocrystalline iron cobalt silicon boron or cobalt silicon boron or iron copper neodymium silicon boron, Its thickness is 10 to 100 nm. 6. The method for preparing a giant magnetoresistive magnetic sensor according to claim 3, characterized in that the conductor in the conductive layer is metal gold or metal silver or metal copper or metal nickel or an alloy of the above metals, and its thickness is 10 ~ 100nm.

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