JP2006310585A - Magnetic sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a small size magnetic sensor capable of detecting the strength of magnetic field of three longitudinals by arranging three pieces or more of giant magnetoresistive elements on one sheet of substrate. <P>SOLUTION: Four pieces of GMR (giant magneto resistive) elements 2a-2d constituting an X-axis sensor, and four pieces of GMR elements 3e-3h constituting a Y-axis sensor, are arranged on the flat surface of a thick film formed on the substrate 1. A Z-axis sensor is constituted of four pieces of GMR elements 4i-4l formed on the inclined surfaces of a plurality of grooves formed by etching a part of the thick film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic sensor and a manufacturing method thereof, and in particular, obtains a small-sized magnetic sensor capable of detecting the strength of a magnetic field in three axial directions by arranging three or more giant magnetoresistive elements on one substrate. It is what I did.

  The present applicant has already disclosed three or more giant magnetoresistive elements on a single substrate according to Japanese Patent Application Laid-Open No. 2004-6752, and can measure the strength of a magnetic field in three axial directions. A sensor is proposed.

In this prior invention, a groove is formed in a silicon substrate, a giant magnetoresistive element for Z-axis detection is disposed on the slope of the groove, and a giant magnetoresistive element for X-axis detection and a Y-axis detection element are arranged on a flat surface of the substrate. A giant magnetoresistive element is arranged and can be miniaturized.
Following this, a peak made of silicon oxide is formed on the substrate, a giant magnetoresistive element for Z-axis detection is arranged on the slope of the peak, and a giant for X-axis detection is placed on the flat surface of the substrate. A three-axis magnetic sensor is proposed in which a magnetoresistive element and a giant magnetoresistive element for Y-axis detection are arranged.

  In this connection, one or more grooves or bank-like protrusions are formed in parallel on the substrate, and giant magnetoresistive elements are provided on the slopes of these grooves or protrusions. The magnetic field strength in the Z-axis direction is measured. On the other hand, two or more giant magnetoresistive elements having sensing axes in the X-axis direction and the Y-axis direction are provided on the flat surface of the substrate. A patent application has also been filed for a triaxial magnetic sensor that can measure the strength of the magnetic field in the direction.

In this prior invention, the groove or the protrusion is formed as follows.
First, a thick film made of silicon oxide or the like is formed on a substrate, and a resist film is provided on the thick film. Next, a resist pattern is formed by removing a portion corresponding to the portion serving as a groove or the portion serving as the bottom of the protrusion from the resist film.

Next, the resist film on which the resist pattern is formed is subjected to heat treatment, and the end surface of the resist film is set as an inclined surface.
Thereafter, plasma etching is performed under an etching condition such that the etching rate ratio between the resist and silicon oxide is approximately 1: 1, and the resist film and the thick film are etched at the same time. This is a method of forming a recess that becomes the bottom.
JP 2004-6752 A

  The present invention is an extension of these prior inventions. Similarly, it is possible to arrange three or more giant magnetoresistive elements on a single substrate and to detect the strength of the magnetic field in the triaxial direction. It is to obtain a magnetic sensor, and in particular, to provide a giant magnetoresistive element having good characteristics by obtaining an inclined surface having a constant inclination angle by facilitating etching control.

To solve this problem,
The invention according to claim 1 includes an etching stopper film formed on a substrate, an insulating film formed on the etching stopper film and having a step forming portion, and a slope of a peak or groove formed in the insulating film. And a magnetoresistive element.
The invention according to claim 2 is the magnetic sensor, wherein the etching stopper film is disposed on the protective film on the substrate and below the magnetoresistive element.

According to a third aspect of the present invention, there is provided a step of forming a first insulating film on a substrate and further forming an etching stopper film, a second insulating film is disposed on the etching stopper film, and the etching stopper film Etching until it is exposed to form a slope on the second insulating film, and forming a magnetoresistive element on the slope.
According to a fourth aspect of the present invention, a planarizing layer that covers the wiring layer and forms a flat surface is formed on the uppermost wiring layer of the substrate, and a part of the planarizing layer is removed to form a via portion. And after exposing the pad part and forming a passivation film composed of an upper layer and a lower layer thereon, the upper layer corresponding to the via part and the pad part is removed,
An etching stopper film is formed thereon to expose portions corresponding to the via portion and the pad portion,
Next, a thick film is formed thereon, and a resist film having a predetermined pattern having a slope is formed on the thick film. Using this as a mask, the thick film is etched until the etching stopper film is exposed to form the slope. At the same time as forming, leaving a part of the thick film in the via part and the pad part,
Next, the thick film remaining in a part of the via part and the lower layer of the passivation film are removed to expose the conductor part of the via part,
Forming a bias magnet film on the flat surface and the inclined surface of the thick film;
A band-shaped portion of a giant magnetoresistive element is formed on the flat surface and the inclined surface of the thick film so as to connect to the bias magnet film and to the via portion,
After the protective film is formed on the entire surface, the conductor part of the pad part is exposed.

  According to the magnetic sensor of the present invention, since the X-axis sensor, the Y-axis sensor, and the Z-axis sensor are arranged on one substrate, it functions as a small three-axis magnetic sensor. In addition, a band-shaped portion of the giant magnetoresistive element can be formed in a portion having a good flatness on the slope of the groove portion, and a magnetic sensor with excellent sensitivity can be obtained.

According to the method for manufacturing a magnetic sensor of the present invention, formation of a groove, formation of a giant magnetoresistive element on the slope of the groove, and formation of a via part and a pad part can be performed as a series of processes. In addition, the etching selectivity between the resist film and the thick film can be increased by etching the resist film and the thick film by using the upper layer forming the passivation film as an etching stopper. It can be formed from the surface opposite to the surface in contact with the upper layer of the film to the surface in contact with the upper thick film.
According to the method for manufacturing a magnetic sensor of the present invention, formation of a groove, formation of a giant magnetoresistive element on the slope of the groove, and formation of a via part and a pad part can be performed as a series of processes. In addition, an insulating film is formed on the passivation film, and the resist film and the thick film are etched using this insulating film as an etching stopper, so that the groove is opposite to the surface in contact with the thick insulating film. It can be formed from the surface to the surface in contact with the thick film of the insulating film.

(Magnetic sensor)
FIG. 1 schematically shows an example of a magnetic sensor obtained by the method of manufacturing a magnetic sensor of the present invention, and shows the arrangement of giant magnetoresistive elements on a substrate.
In FIG. 1, reference numeral 1 denotes a substrate. In this substrate 1, a semiconductor integrated circuit such as a magnetic sensor driving circuit, a signal processing circuit, a wiring layer, and the like are formed in advance on a semiconductor substrate such as silicon, and a planarization film, a passivation film, a silicon oxide film, and the like are formed thereon. The thick films are sequentially stacked, and these films are not shown.

On the thick film of the substrate 1, an X-axis sensor 2, a Y-axis sensor 3, and a Z-axis sensor 4 are provided. The X-axis sensor 2 has a sensing axis in the X direction, the Y-axis sensor 3 has the same Y direction, and the Z-axis sensor 4 has the same sensing axis in the Z direction.
The X-axis sensor 2 is composed of four giant magnetoresistive elements 2a, 2b, 2c and 2d, and the Y-axis sensor 3 is composed of four giant magnetoresistive elements 3e, 3f, 3g and 3h. The sensor 4 is composed of four giant magnetoresistive elements 4i, 4j, 4k, and 4l.

  Of the four giant magnetoresistive elements constituting the X-axis sensor 2, the giant magnetoresistive elements 2a, 2b are provided side by side at substantially the center of the substrate 1, and the remaining two giant magnetoresistive elements 2c, 2d are They are provided so as to be opposed to the giant magnetoresistive elements 2a and 2b alongside each other at the end of the substrate 1 that is slightly separated from these.

  Of the four giant magnetoresistive elements forming the Y-axis sensor 3, the giant magnetoresistive elements 3e and 3f are arranged on one end side of the substrate 1, and the remaining two giant magnetoresistive elements 3g and 3h are The other end side of the substrate 1 is arranged side by side so as to face the giant magnetoresistive elements 3e and 3f.

  Of the four giant magnetoresistive elements forming the Z-axis sensor 4, the two giant magnetoresistive elements 4k, 4l are arranged side by side at positions close to the giant magnetoresistive elements 3e, 3f, and the remaining two The giant magnetoresistive elements 4i and 4j are arranged side by side at a position slightly away from the giant magnetoresistive elements 2a and 2b.

These giant magnetoresistive elements are basically the same as conventional giant magnetoresistive elements. In this example, as shown in FIG. 2, four strips 5, 5, 5, 5 and these It is comprised from the three bias magnet parts 6, 6, and 6 which electrically connect the strip | belt-shaped parts 5, 5, 5, and 5 in series.
The belt-like portion 5 is a portion that forms the main body of the giant magnetoresistive element, and has an elongated belt-like planar shape.

  The band-shaped portion 5 includes a pinned layer in which the magnetization direction is fixed in a predetermined direction, and a free layer in which the magnetization direction changes in accordance with the direction of the external magnetic field. It is composed of a multilayer metal thin film laminate in which a conductive spacer layer, a pinned layer, and a capping layer are sequentially laminated.

  As the free layer, for example, a layer composed of a cobalt-zirconium-niobium amorphous magnetic layer, a nickel-cobalt magnetic layer, and a cobalt-iron magnetic layer is used. As the spacer layer, for example, a layer made of copper is used. As the pinned layer, for example, a layer composed of two layers of a cobalt-iron ferromagnetic layer and a platinum-manganese diamagnetic layer is used. As the capping layer, for example, a layer made of tantalum is used.

  The bias magnet unit 6 is for electrically connecting the four strips 5, 5, 5, 5 in series and for applying a bias magnetic field for adjusting the magnetic characteristics of the strip 5 to the strip 5 It is. Moreover, this bias magnet part 6 is comprised from the thin film metal laminated body which consists of two layers of a cobalt-platinum-chromium layer and a chromium layer, for example.

  The structures of the giant magnetoresistive elements 2a, 2b, 2c, 2d, 3e, 3f, 3g, 3h constituting the X-axis sensor 2 and the Y-axis sensor 3 provided on the flat surface of the substrate 1 are as shown in FIG. It is composed of four belt-like parts 5, 5, 5, 5 and three bias magnet parts 6, 6, 6. Wiring layers 7 and 7 are connected to the ends of the four belt-like portions 5, 5, 5, and 5, which are not connected to the bias magnet portions 6 of the two belt-like portions 5 and 5 on the outer sides. The wiring layers 7 are connected to via portions (not shown).

  FIGS. 3 to 5 show the structures of giant magnetoresistive elements 4i and 4j among the four giant magnetoresistive elements constituting the Z-axis sensor 4. FIG. Since the other giant magnetoresistive elements 4k and 4l have the same structure as the giant magnetoresistive elements 4i and 4j, description thereof will be omitted.

  3 is a schematic plan view of the giant magnetoresistive elements 4i and 4j, FIG. 4 is a schematic sectional view taken along the broken line IV-IV in FIG. 3, and FIG. 5 is a strip portion of the giant magnetoresistive element. 5 is a perspective view schematically showing an arrangement state of 5 and the bias magnet unit 6. FIG.

In FIG. 4, reference numeral 1 denotes a substrate, and reference numeral 11 denotes a thick film made of silicon oxide or the like deposited on the substrate 1.
The thick film 11 is provided with four V-shaped grooves 8, 8, 8, 8 that are formed by partially scraping the thick film 11 in parallel with each other. A layer 12 (hereinafter referred to as an “etching stopper layer”) that functions as an etching stopper made of a passivation film or an insulating film, which will be described later, is provided between the substrate 1 and the thick film 11.

The groove 8 is an elongated recess having a depth of 3 μm to 7 μm and a length of 250 μm to 300 μm, and the slope has a width of 3 μm to 8 μm. The angle formed between the slope of the groove 8 and the surface of the thick film 11 is 60 to 80 degrees, preferably about 70 degrees.
In FIG. 4, the inclined surface of the groove 8 is depicted as a flat surface, but in actuality, it is a curved surface that slightly protrudes outward in the manufacturing process.

Further, the eight giant magnetoresistive elements are arranged on the eight slopes adjacent to each other in the grooves 8, 8, 8, 8 along the longitudinal direction of the slope and in a position where the flatness of the central portion of the slope is good. Strips 5, 5, 5, 5 are provided.
Of these eight slopes, one of the strips 5 formed on the adjacent second slope 8c from the one end of the strip 5 formed on the first slope 8a through the bottom 8b of the groove 8 A bias magnet portion 6 is provided over the ends of the two and is electrically connected.

Also, from the other end of the strip 5 formed on the second slope 8c to one end of the strip 5 formed on the adjacent third slope 8e across the top 8d of the groove 8 A bias magnet unit 6 is provided and electrically connected.
Further, the bias magnet portion extends from the other end portion of the strip-shaped portion 5 formed on the third inclined surface 8e through the bottom portion 8f of the groove 8 to one end portion of the strip-shaped portion 5 formed on the adjacent fourth inclined surface 8g. 6 is provided and is electrically connected to form one giant magnetoresistive element 4i.
Similarly, the remaining four belt-like portions 5, 5, 5, 5 are connected in series by the three bias magnet portions 6, 6, 6 to constitute one giant magnetoresistive element 4j. .

  Further, in the same manner as the giant magnetoresistive elements forming the X-axis sensor 2 and the Y-axis sensor 3 provided on the flat portion of the thick film 11, the two outer portions of these strip-shaped portions 5, 5, 5, 5 are used. Wiring layers 7 and 7 are connected to the end portions of the belt-like portions 5 and 5 where the bias magnet portion 6 is not connected, and the wiring layers 7 and 7 are connected to a via portion (not shown). In this example, the wiring layer 7 is composed of a magnet film that forms the bias magnet portion 6 of the giant magnetoresistive element, whereby the bias magnet portion 6 and the wiring layer 7 can be formed simultaneously.

  Further, in the giant magnetoresistive element forming the X-axis sensor 2 and the giant magnetoresistive element forming the Y-axis sensor 3, as shown in FIG. 2, the sensing axis is orthogonal to the longitudinal direction of the strip 5 (in the drawing). (In the direction of the arrow) is directed parallel to the surface of the substrate 1. The pinning direction of the strip 5 and the magnetization direction of the bias magnetic field of the bias magnet 6 are 30 to 60 degrees, preferably 45 degrees with respect to the longitudinal direction of the strip 5 and are parallel to the surface of the substrate 1. ing.

  Further, in the giant magnetoresistive elements 4i and 4j constituting the Z-axis sensor 4, the sensing axis thereof is orthogonal to the longitudinal direction of the strip 5 (in the direction of the arrow in the figure), as shown in FIG. The groove 8 is parallel to the slope and is directed upward. Further, the pinning direction of the belt-shaped portion 5 and the magnetization direction of the bias magnetic field of the bias magnet portion 6 are 30 to 60 degrees, preferably 45 degrees with respect to the longitudinal direction of the belt-shaped portion 5. It is facing upward.

  On the other hand, in the giant magnetoresistive elements 4k and 4l forming the Z-axis sensor 4, as shown in FIG. 6, the sensing axis is perpendicular to the longitudinal direction of the strip 5 (in the direction of the arrow in the figure). It is parallel to the slope of the groove 8 and is directed downward on the slope. Further, the pinning direction of the belt-shaped portion 5 and the magnetization direction of the bias magnetic field of the bias magnet portion 6 are 30 to 60 degrees, preferably 45 degrees with respect to the longitudinal direction of the belt-shaped portion 5. It is facing downward.

  In order to obtain such a sense axis direction, it is only necessary to heat the substrate at 260 to 290 ° C. for 3 hours to 5 hours with the magnet array approached from above. This is the same as the pinning process.

  In a normal giant magnetoresistive element, the sensing axis direction and the pinning direction are both perpendicular to the longitudinal direction of the strip and parallel to the substrate surface. On the other hand, in the present invention, as described above, the magnetic field resistance of the giant magnetoresistive element is improved by making the sensing axis direction and the pinning direction of the belt-like portion 5 different.

  7 shows four giant magnetoresistive elements 2a, 2b, 2c and 2d forming the X-axis sensor 2 described above, four giant magnetoresistive elements 3e, 3f, 3g, 3h forming the Y-axis sensor 3, and This shows the connection method of the four giant magnetoresistive elements 4i, 4j, 4k, and 4l forming the Z-axis sensor 4, and shows the bridge connection of the outputs of the four giant magnetoresistive elements of each axis sensor. Yes.

  By performing such bridge connection, when a magnetic field is applied in the positive direction of the X-axis, Y-axis, and Z-axis of the coordinate axes in FIG. 1, the respective X-axis sensor 2, Y-axis sensor 3, and Z-axis sensor 4 When the magnetic field is applied in the opposite direction, a characteristic that the output from each of the X-axis sensor 2, the Y-axis sensor 3, and the Z-axis sensor 4 decreases is obtained.

  Although not shown in FIGS. 1 to 6, the entire surface of the substrate 1 including all the giant magnetoresistive elements constituting the X-axis sensor 2, the Y-axis sensor 3, and the Z-axis sensor 4 is made of silicon nitride or the like. A passivation film such as a passivation film and polyimide is coated, and each sensor is protected from the outside.

FIG. 8 shows an example of the structure of the via portion provided in the substrate 1. In FIG. 8, reference numeral 21a indicates a conductor portion made of aluminum or the like constituting the via portion, and this conductor portion 21a is formed on the lower layer. It is electrically connected to the wiring part.
The peripheral portion of the surface of the conductor portion 21 a is covered with the above-described planarization film 22, passivation film 23, and thick film 11. The edge portion of the thick film 11 is an inclined surface as illustrated.

  Furthermore, the central portion of the surface of the conductor portion 21 is covered with a wiring film 25, and this wiring film 25 is connected to the wiring layer 7 of the giant magnetoresistive element described above. Similarly to the wiring layer 7, the wiring film 25 is also composed of a magnet film that forms the bias magnet portion 6, and can be manufactured simultaneously with the bias magnet portion 6.

  As shown in the figure, the wiring film 25 has a stepped step at the edge of the thick film 11. At the corner of the stepped portion, the thickness of the wiring film 25 becomes thin due to the process, and there is a risk of disconnection. For this reason, the protective conductor film 26 is laminated on the wiring film 25 so as to cover the step portion and the central portion.

As this protective conductor film 26, in this example, a giant magnetoresistive element film forming the strip-like part 5 of the giant magnetoresistive element is used. According to this, the protective film 26 is protected on the wiring film 25 simultaneously with the production of the strip-like part 5. The conductor film 26 can be laminated. As a result, the possibility of disconnection of the wiring film 25 can be avoided.
Furthermore, such a via portion is covered with a passivation film 27 such as silicon nitride and a protective film 28 such as polyimide, and is protected from the outside.

  In such a magnetic sensor, since the X-axis sensor 2, the Y-axis sensor 3, and the Z-axis sensor 4 are arranged on one substrate 1, it functions as a small three-axis magnetic sensor. In addition, a band-shaped portion of the giant magnetoresistive element can be formed in a portion having good flatness on the slope of the groove 8, and a magnetic sensor having excellent sensitivity can be obtained.

The protective conductor film 26 made of a giant magnetoresistive element film is laminated on the wiring film 25 made of a bias magnet film at the opening edge of the via portion, and the possibility of disconnection of the wiring film 25 at the corner portion is reduced.
Furthermore, by setting the pinning direction of the belt-like portion 5 to 30 to 60 degrees with respect to the longitudinal direction of the belt-like portion 5, the magnetic field resistance of the obtained giant magnetoresistive element is improved.

(First Embodiment of Magnetic Sensor Manufacturing Method)
Next, a first embodiment of a method for manufacturing a magnetic sensor according to the present invention will be described.
In the following description, a method for manufacturing a giant magnetoresistive element, a via portion, and a pad portion constituting the Z-axis sensor 4 formed on the slopes of the grooves 8, 8,.
First, the substrate 1 is prepared. As described above, the substrate 1 is formed by previously forming a semiconductor integrated circuit such as a magnetic sensor driving circuit, a signal processing circuit, a wiring layer, or the like on a semiconductor substrate such as silicon.

  As shown in FIG. 9 (a), the substrate 1 includes a conductor portion 21a made of aluminum or the like of the via portion A and a conductor portion made of aluminum or the like of the pad portion B, which form part of the uppermost wiring layer. 21b is provided.

  A planarizing film 31 is first formed on the substrate 1. As the planarizing film 31, for example, a silicon oxide film having a thickness of 300 nm by a plasma CVD method, a SOG film having a thickness of 600 nm, and a silicon oxide film having a thickness of 50 nm formed using triethoxysilane as a raw material are sequentially used. It is done.

  Next, as shown in FIG. 9B, the planarizing film 31 on the conductor portions 21a and 21b of the via portion A and the pad portion B is removed by etching, and the conductor portions 21a and 21b are opened.

  Further, as shown in FIG. 9C, a passivation film 32 is formed on the entire surface of the substrate 1. The passivation film 32 is, for example, a laminated film of a silicon oxide film 33 having a thickness of 250 nm formed by a plasma CVD method and a silicon nitride film 34 having a thickness of 600 nm formed by a plasma CVD method and formed as an upper layer. Is used.

  Next, as shown in FIG. 9D, the silicon nitride film 34 deposited above the conductor portions 21a and 21b of the via portion A and the pad portion B is removed by etching. At this time, the silicon oxide film 33 is left, and the removal range of the silicon nitride film 34 is made smaller than the opening width of the planarizing film 31. By doing so, the end face of the planarizing film 31 is exposed in the opening portions of the via portion A and the pad portion B, and moisture may invade into a wiring layer, a semiconductor integrated circuit, or the like formed on the substrate 1. Is prevented.

  Next, as shown in FIG. 10A, a thick film 35 made of silicon oxide is formed thereon by a plasma CVD method having a thickness of about 5 μm. As described later, the thick film 35 is formed with the grooves 8, 8,...

  Next, as shown in FIG. 10B, a resist film 36 having a thickness of about 3 μm is formed on the entire surface of the thick film 35. A part of the resist film 36 is removed by etching to form a resist pattern. In this resist pattern, only the portion corresponding to each groove of the groove forming portion C, the via portion A, and the pad portion B are opened.

  Next, as shown in FIG. 10C, the remaining resist film 36 is heated at a temperature of 150 ° C. for about 10 minutes to melt the resist film 36. Due to this heat treatment, the resist is melted, and due to the surface tension of the melt, the upper surface of the resist 36 film rises and the end surface becomes an inclined surface as shown in the figure. In particular, in the resist film 36 corresponding to the groove forming portion C, the cross-sectional shape is a mountain shape, and the height rises to about 5 μm.

Thereafter, as shown in FIG. 11A, dry etching is performed on the resist film 36 and the thick film 35 by using the silicon nitride film 34 that forms the upper layer of the passivation film 32 as an etching stopper. Are formed in the via portion A and the pad portion B at the same time as the grooves 8, 8,.
By using the silicon nitride film 34 as an etching stopper, dry etching is terminated when the silicon nitride film 34 is exposed in the groove forming portion C.

The dry etching conditions are as follows.
For example, reactive ion etching (RIE) is performed using a mixed gas of C ₄ F ₈ / Ar / CH ₂ F ₂ = 7/500/4 sccm, gas pressure = 50 mTorr, and RF power = 1500 W.

  By setting the dry etching conditions as described above, the etching selectivity between the resist forming the resist film 36 and the silicon oxide forming the thick film 35 can be increased, so that the silicon nitride film 34 is used as an etching stopper. be able to. As a result, as shown in FIG. 11A, the grooves 8, 8,... Are formed from the surface opposite to the surface in contact with the silicon nitride film 34 of the thick film 35 to the thick film 35 of the silicon nitride film 34. It can be formed over the contacting surface. Also, according to the dry etching conditions described above, the etching selectivity between the resist forming the resist film 36 and the silicon oxide forming the thick film 35 can be set to 6, for example.

At the time of this dry etching, as shown in FIG. 11A, in the via portion A and the pad portion B, the size of the opening is not made larger than the size of the opening of the passivation film 32.
Thereafter, the resist film 36 remaining on the thick film 35 is removed.

  As a result, as shown in FIG. 11A, grooves 8, 8,... Are formed in the groove forming portion C of the thick film 35. Further, as shown in FIG. 11B, the thick film 35 and the silicon oxide film 33 covering the conductor part 21a of the via part A are removed by etching, and the conductor part 21a is exposed.

  Next, a magnet film serving as the bias magnet portion 6 of the giant magnetoresistive element is formed on the entire surface of the substrate 1 by sputtering, and unnecessary portions are removed by resist work and etching. As shown in FIG. , 8,..., 8 are formed, and at the same time, a wiring film 25 is formed on the conductor part 21a of the via part A. The wiring film 25 and the bias magnet part of the giant magnetoresistive element are formed. 6 is formed.

As this magnet film, a multilayer metal thin film as described above is used.
At this time, the bias magnet portion 6 and the wiring layer 7 of each giant magnetoresistive element constituting the X-axis sensor 2 and the Y-axis sensor 3 are also formed on the flat surface of the thick film 35.

  At the time of resist work for forming the bias magnet portion 6, in order to appropriately etch the magnet film on the slope of the groove 8, the resist film after pattern formation is subjected to heat treatment so that the end face of the resist film is removed. It is preferable to use an inclined surface.

Next, a giant magnetoresistive element film to be the band-like portion 5 of the giant magnetoresistive element is formed on the entire surface by sputtering. As this giant magnetoresistive element film, the multilayer metal thin film as described above is used.
Further, the substrate 1 in this state is set on a magnet array, and heat treatment is performed at a temperature of 260 to 290 ° C. for 3 hours to 5 hours, and a pinning process is performed on the giant magnetoresistive element film.

  Thereafter, resist work and etching are performed on the giant magnetoresistive element film to remove unnecessary portions, and as shown in FIG. 12 (a), the strip 5 is formed on the slopes of the grooves 8, 8,. Are formed to produce a giant magnetoresistive element. Thereby, the Z-axis sensor 4 is completed.

At the same time, the giant magnetoresistive element film is also left on the wiring film 25 made of a magnet film previously formed on the conductor part 21 a of the via part A, thereby forming the protective conductor film 26. Thereby, the structure of the via part A shown in FIG. 8 is obtained.
At the same time, the band-like portion 5 is formed on the flat surface of the thick film 35 to produce a giant magnetoresistive element. Thereby, the X-axis sensor 2 and the Y-axis sensor 3 are completed.

  Next, as shown in FIG. 12B, a passivation film 27 made of a silicon nitride film having a thickness of 1 μm is formed by plasma CVD, and a protective film 28 made of polyimide is further provided thereon. Further, portions of the protective film 28 and the passivation film 27 in the pad portion B are removed and opened.

  Next, as shown in FIG. 12C, etching is performed using the protective film 28 as a mask to remove the silicon oxide film 33 and the thick film 35 covering the conductor portion 28 of the pad portion B, and the pad portion B The conductor part 21b is exposed to obtain a target magnetic sensor.

  According to such a magnetic sensor manufacturing method, the X-axis sensor 2, the Y-axis sensor 3, and the Z-axis sensor 4 can be manufactured on one substrate, and at the same time, the via portion and the pad portion are also manufactured. Thus, a small three-axis magnetic sensor can be manufactured at once by a series of continuous processes. Further, by etching the resist film 36 and the thick film 35 using the silicon nitride film 34 as an etching stopper, the grooves 8, 8,... Are in contact with the surface of the thick film 35 in contact with the silicon nitride film 34. Can be formed from the opposite surface to the surface in contact with the thick film 35 of the silicon nitride film 34. Thereby, it is possible to form a slope having a predetermined angle necessary for forming a giant magnetoresistive element type magnetic sensor with a sensitivity component in a direction perpendicular to the substrate surface.

(Second Embodiment of Magnetic Sensor Manufacturing Method)
Next, a second embodiment of the magnetic sensor manufacturing method according to the present invention will be described.
In the following description, in the same manner as in the first embodiment, a giant magnetoresistive element, a via portion, and a Z-axis sensor 4 formed on the slopes of the grooves 8, 8,. A method for manufacturing the pad portion will be described.
First, the substrate 1 is prepared. As described above, the substrate 1 is formed by previously forming a semiconductor integrated circuit such as a magnetic sensor driving circuit, a signal processing circuit, a wiring layer, or the like on a semiconductor substrate such as silicon.

  As shown in FIG. 13A, the substrate 1 has a conductor portion 21a made of aluminum or the like of the via portion A and a conductor portion made of aluminum or the like of the pad portion B, which forms a part of the uppermost wiring layer. 21b is provided.

  A planarizing film 31 is first formed on the substrate 1. As the planarizing film 31, for example, a silicon oxide film having a thickness of 300 nm by a plasma CVD method, a SOG film having a thickness of 600 nm, and a silicon oxide film having a thickness of 50 nm formed using triethoxysilane as a raw material are sequentially used. It is done.

  Next, as shown in FIG. 13B, the planarizing film 31 on the conductor portions 21a and 21b of the via portion A and the pad portion B is removed by etching, and the conductor portions 21a and 21b are opened.

  Further, as shown in FIG. 13C, a passivation film 32 is formed on the entire surface of the substrate 1. The passivation film 32 is, for example, a laminated film of a silicon oxide film 33 having a thickness of 250 nm formed by a plasma CVD method and a silicon nitride film 34 having a thickness of 600 nm formed by a plasma CVD method and formed as an upper layer. Is used.

  Next, as shown in FIG. 13D, the silicon nitride film 34 deposited above the conductor portions 21a and 21b of the via portion A and the pad portion B is removed by etching. At this time, the silicon oxide film 33 is left, and the removal range of the silicon nitride film 34 is made smaller than the opening width of the planarizing film 31. By doing so, the end face of the planarizing film 31 is exposed in the opening portions of the via portion A and the pad portion B, and the wiring layer or semiconductor layer formed on the substrate 1 is exposed. It is possible to prevent moisture from entering a body integrated circuit or the like.

Next, as shown in FIG. 14A, an insulating film 37 having a thickness of about 0.2 μm is formed thereon by sputtering. Examples of the insulating film 37 include films made of aluminum oxide (Al ₂ O ₃ ), boron nitride (BN), diamond-like carbon, and the like.

  Next, as shown in FIG. 14B, a resist film 38 having a thickness of about 3 μm is formed on the entire surface of the insulating film 37.

  Next, as shown in FIG. 14C, a part of the resist film 38 is removed by an etching process to form a resist pattern. This resist pattern exposes the insulating film 37 so that only the via part A and the pad part B are opened.

  Next, as shown in FIG. 15A, the insulating film 37 corresponding to the via portion A and the pad portion B is removed by ion milling to expose the silicon oxide film 33.

  Next, as shown in FIG. 15B, the remaining resist film 38 is removed.

  Next, as shown in FIG. 16A, a thick film 35 made of silicon oxide is formed thereon by a plasma CVD method having a thickness of about 5 μm. As described later, the thick film 35 is formed with the grooves 8, 8,...

  Next, as shown in FIG. 16B, a resist film 36 having a thickness of about 3 μm is formed on the entire surface of the thick film 35. A part of the resist film 36 is removed by etching to form a resist pattern. In this resist pattern, only the portion corresponding to each groove of the groove forming portion C, the via portion A, and the pad portion B are opened.

  Next, as shown in FIG. 16C, the remaining resist film 36 is heated at a temperature of 150 ° C. for about 10 minutes to melt the resist film 36. Due to this heat treatment, the resist is melted, and due to the surface tension of the melt, the upper surface of the resist 36 film rises and the end surface becomes an inclined surface as shown in the figure. In particular, in the resist film 36 corresponding to the groove forming portion C, the cross-sectional shape is a mountain shape, and the height rises to about 5 μm.

  Thereafter, as shown in FIG. 17A, the insulating film 37 is used as an etching stopper, and the resist film 36 and the thickness are formed under the condition that the etching selection ratio between the resist and silicon oxide is approximately 1: 1. The film 35 is dry-etched to form the grooves 8, 8,... In the thick film 35, and at the same time, the thin thick film 35 is left in the via part A and the pad part B.

The dry etching conditions are as follows.
For example, single-wafer reactive ion etching (RIE) is performed using a mixed gas of CF ₄ / CHF ₃ / N ₂ = 30/90/5 sccm, gas pressure = 200 mTorr, and RF power = 750 W.

  By setting the dry etching conditions as described above, the etching selectivity between the resist forming the resist film 36 and the silicon oxide forming the thick film 35 can be made substantially 1: 1, so that the insulating film 37 can be used as an etching stopper. Can be used as As a result, as shown in FIG. 11A, the grooves 8, 8,... Are in contact with the thick film 35 of the insulating film 37 from the surface opposite to the surface of the thick film 35 that contacts the insulating film 37. Can be formed over.

At the time of this dry etching, as shown in FIG. 17A, in the via portion A and the pad portion B, the size of the opening is not made larger than the size of the opening of the passivation film 32.
Thereafter, the resist film 36 remaining on the thick film 35 is removed.

  As a result, as shown in FIG. 17A, grooves 8, 8,... Are formed in the groove forming portion C of the thick film 35. Further, as shown in FIG. 17B, the thick film 35 and the silicon oxide film 33 covering the conductor part 21a of the via part A are removed by etching to expose the conductor part 21a.

  Next, a magnet film serving as the bias magnet portion 6 of the giant magnetoresistive element is formed on the entire surface of the substrate 1 by sputtering, and unnecessary portions are removed by resist work and etching. As shown in FIG. , 8,..., 8 are formed, and at the same time, a wiring film 25 is formed on the conductor part 21a of the via part A. The wiring film 25 and the bias magnet part of the giant magnetoresistive element are formed. 6 is formed.

As this magnet film, a multilayer metal thin film as described above is used.
At this time, the bias magnet portion 6 and the wiring layer 7 of each giant magnetoresistive element constituting the X-axis sensor 2 and the Y-axis sensor 3 are also formed on the flat surface of the thick film 35.

  At the time of resist work for forming the bias magnet portion 6, in order to appropriately etch the magnet film on the slope of the groove 8, the resist film after pattern formation is subjected to heat treatment so that the end face of the resist film is removed. It is preferable to use an inclined surface.

Next, a giant magnetoresistive element film to be the band-like portion 5 of the giant magnetoresistive element is formed on the entire surface by sputtering. As this giant magnetoresistive element film, the multilayer metal thin film as described above is used.
Further, the substrate 1 in this state is set on a magnet array, and heat treatment is performed at a temperature of 260 to 290 ° C. for 3 hours to 5 hours, and a pinning process is performed on the giant magnetoresistive element film.

  Thereafter, resist work and etching are performed on the giant magnetoresistive element film to remove unnecessary portions, and as shown in FIG. 18 (a), the strip 5 is formed on the slopes of the grooves 8, 8,. Are formed to produce a giant magnetoresistive element. Thereby, the Z-axis sensor 4 is completed.

At the same time, the giant magnetoresistive element film is also left on the wiring film 25 made of a magnet film previously formed on the conductor part 21 a of the via part A, thereby forming the protective conductor film 26. Thereby, the structure of the via part A shown in FIG. 8 is obtained.
At the same time, the band-like portion 5 is formed on the flat surface of the thick film 35 to produce a giant magnetoresistive element. Thereby, the X-axis sensor 2 and the Y-axis sensor 3 are completed.

  Next, as shown in FIG. 18B, a passivation film 27 made of a silicon nitride film having a thickness of 1 μm is formed by plasma CVD, and a protective film 28 made of polyimide is further provided thereon. Further, portions of the protective film 28 and the passivation film 27 in the pad portion B are removed and opened.

  Next, as shown in FIG. 18C, etching is performed using the protective film 28 as a mask to remove the silicon oxide film 33 and the thick film 35 covering the conductor portion 28 of the pad portion B, and The conductor part 21b is exposed to obtain a target magnetic sensor.

  According to such a magnetic sensor manufacturing method, the X-axis sensor 2, the Y-axis sensor 3, and the Z-axis sensor 4 can be manufactured on one substrate, and at the same time, the via portion and the pad portion are also manufactured. Thus, a small three-axis magnetic sensor can be manufactured at once by a series of continuous processes. Further, by forming an insulating film 37 on the passivation film 32 and using this insulating film as an etching stopper, the resist film 36 and the thick film 35 are etched to form the grooves 8, 8,. The thick film 35 can be formed from the surface opposite to the surface in contact with the insulating film 37 to the surface in contact with the thick film 35 of the insulating film 37. Thereby, it is possible to form a slope having a predetermined angle necessary for forming a giant magnetoresistive element type magnetic sensor with a sensitivity component in a direction perpendicular to the substrate surface. Further, by forming the insulating film 37 on the passivation film 32, it becomes easy to control the groove shape in the depth direction.

  The present invention can also be applied to an electronic compass mounted on various portable electronic devices including a mobile phone.

It is a schematic plan view which shows an example of the magnetic sensor of this invention. It is a schematic plan view which shows the example of the GMR element in this invention. It is a schematic plan view which shows the example of the GMR element which comprises the Z-axis sensor in this invention. It is a schematic sectional drawing which shows the example of the GMR element which comprises the Z-axis sensor in this invention. It is a schematic perspective view which shows the example of the GMR element which comprises the Z-axis sensor in this invention. It is a schematic perspective view which shows the other example of the GMR element which comprises the Z-axis sensor in this invention. It is explanatory drawing which shows the example of the connection method of the GMR element which makes each axis | shaft sensor in this invention. It is a schematic sectional drawing which shows the example of the structure of the via part of the magnetic sensor of this invention. It is a schematic sectional drawing which shows 1st embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows 1st embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows 1st embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows 1st embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows 2nd embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows 2nd embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows 2nd embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows 2nd embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows 2nd embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows 2nd embodiment of the manufacturing method of the magnetic sensor of this invention to process order.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... X-axis sensor, 3 ... Y-axis sensor, 5 ... Band-shaped part, 6 ... Bias magnet part, 7 ... Wiring layer, A ... Via part , B ... pad part, 8 ... groove, 21a, 21b ... conductor part, 25 ... wiring film, 27 ... passivation film, 28 ... protective film, 31 ... flattening 32 ... Passivation film, 33 ... Silicon oxide film, 34 ... Silicon nitride film, 35 ... Thick film, 36 ... Resist film, 37 ... Insulating film, 38 ... Resist film.

Claims (4)

  A magnetoresistive element is disposed on an etching stopper film formed on the substrate, an insulating film formed on the etching stopper film and having a step forming portion, and a slope of a peak or groove formed in the insulating film. Magnetic sensor characterized by the above.   2. The magnetic sensor according to claim 1, wherein the etching stopper film is disposed on the protective film on the substrate and below the magnetoresistive element.   Forming a first insulating film on the substrate and further forming an etching stopper film; arranging a second insulating film on the etching stopper film; etching until the etching stopper film is exposed; A method of manufacturing a magnetic sensor, comprising: forming a slope on the second insulating film; and forming a magnetoresistive element on the slope. A planarizing layer that covers the wiring layer and forms a flat surface is formed on the uppermost wiring layer of the substrate, and a part of the planarizing layer is removed to expose the via portion and the pad portion. After forming a passivation film consisting of an upper layer and a lower layer on top, the upper layer corresponding to the via portion and the pad portion is removed,
An etching stopper film is formed thereon to expose portions corresponding to the via portion and the pad portion,
Next, a thick film is formed thereon, and a resist film having a predetermined pattern having a slope is formed on the thick film. Using this as a mask, the thick film is etched until the etching stopper film is exposed to form the slope. At the same time as forming, leaving a part of the thick film in the via part and the pad part,
Next, the thick film remaining in a part of the via part and the lower layer of the passivation film are removed to expose the conductor part of the via part,
Forming a bias magnet film on the flat surface and the inclined surface of the thick film;
A band-shaped portion of a giant magnetoresistive element is formed on the flat surface and the inclined surface of the thick film so as to connect to the bias magnet film and to the via portion,
A method of manufacturing a magnetic sensor, comprising: forming a protective film on the entire surface, and exposing the conductor portion of the pad portion.

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