JP2007157979A - Magnetic sensor and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a small-sized magnetic sensor capable of detecting magnetic field intensity in three axial directions by providing three or more giant magnetoresistive elements similarly on a single substrate. <P>SOLUTION: Four GMR elements 2a to 2d constituting an X-axis sensor and four GMR elements 3e to 3h constituting a Y-axis sensor are placed on a thick flat plane formed on the substrate 1. A Z-axis sensor is constituted of four GMR elements 4i to 4l formed on slopes 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 method of manufacturing a magnetic sensor, and in particular, to obtain a small magnetic sensor capable of detecting the strength of a magnetic field in three axes by arranging three or more giant magnetoresistive elements on a single substrate. It is a thing.

  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 arranged 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 a sense axis of the X-axis direction and the Y-axis method are provided on the flat surface of the substrate. A patent application has also been filed for a three-axis magnetic sensor that can measure the strength of the magnetic field.

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 the 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 used as an inclined surface.
After this, 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 simultaneously, so that the thick film has a recess or protrusion. It is a method of forming the recessed part used as the bottom part.

  However, since the inclined surface obtained by heat-treating the resist in this way becomes a convex shape upward, it is difficult to make the inclination of the thick film inclined uniform with etching using such a shaped resist as a mask. It is.

For this reason, the inclination angle is different between above and below the same slope of the groove or the protrusion, and depending on the arrangement position of the giant magnetoresistive element in the vertical direction, the output of each of the X, Y, and Z components is different. The characteristics are inferior.
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, by specifying the vertical position of the slope on which the giant magnetoresistive element is placed, each element can be placed on the slope with the same slope angle and the output of each component can be increased. And a giant magnetoresistive element having good characteristics is provided.

To solve this problem,
The invention according to claim 1 is an insulating film having a step forming portion formed on a substrate;
The insulating film is formed of a first inclined surface and a second inclined surface that is formed continuously with the first inclined surface and has a steeper angle with respect to the substrate surface than the first inclined surface. Ridges and grooves,
And a magnetoresistive element disposed on the second inclined surface.

In the invention according to claim 2, an insulating film is formed on the substrate,
The insulating film is etched to form a first slope and a second slope formed continuously with the first slope and having a steeper angle with respect to the substrate surface than the first slope. Forming ridges and grooves to be formed;
A method of manufacturing a magnetic sensor, comprising: forming a magnetoresistive element on the second inclined surface and the flat surface of the insulating film.

According to a third aspect of the present invention, a flattening layer that covers the wiring layer and forms a flat surface is formed on the uppermost wiring layer of the substrate, and a passivation film is formed thereon,
A thick film is formed on this, and a resist film is further formed on this thick film.
Part of this resist film is removed, the remaining resist film is subjected to heat treatment, and the side surface of the resist film is formed as an inclined surface.
Next, the resist film and the thick film are etched under an etching condition in which the etching selectivity is approximately 1: 1 to form a groove in the thick film,
Next, the thick magnet flat surface, the second slope forming the slope of the groove, and the bias magnet part of the giant magnetoresistive element were formed on the top or bottom, and the giant magnetoresistive element film was formed thereon. After that, the substrate is placed on the magnet array and heat treated,
Next, a part of the giant magnetoresistive element film is removed by etching, and a band portion of the giant magnetoresistive element is formed on the flat surface of the thick film and the second slope on the passivation film side of the slope of the groove. The method of manufacturing a magnetic sensor is characterized in that a protective film is formed thereon.

According to a fourth aspect of the present invention, a flattening layer that covers the wiring layer and forms a flat surface is formed on the uppermost wiring layer of the substrate, and after forming a passivation film thereon,
A thick film is formed on this, a groove is formed in this thick film,
Next, the thick flat surface, the second slope forming the slope of the groove, and the bias magnet part of the giant magnetoresistive element are formed on the top or bottom, and the giant magnetoresistive element film is formed thereon. ,
Next, a part of the giant magnetoresistive element film is removed by etching, and a band portion of the giant magnetoresistive element is formed on the flat surface of the thick film and the second slope on the passivation film side of the slope of the groove. The method of manufacturing a magnetic sensor is characterized in that a protective film is formed thereon.

  According to the first aspect of the present invention, it is possible to obtain a small magnetic sensor capable of detecting the strength of the magnetic field in the triaxial direction.

  According to the second to fourth aspects of the present invention, the formation of the groove, the formation of the giant magnetoresistive element on the slope of the groove, and the formation of the via portion and the pad portion can be performed as a series of processes. Further, by providing the band-shaped portion of the giant magnetoresistive element film on the first surface on the passivation film side of the slope of the groove formed in the thick film, the surface of the band-shaped portion forms a more uniform flat surface. Therefore, the magnetic sensor in which the band-like portion of the giant magnetoresistive element is provided on such a slope can be made highly sensitive with the orientation of the sensing axis of the Z-axis sensor aligned.

(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-iron 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 configured to electrically connect the four strips 5, 5, 5, 5 in series and to apply 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).

  3 to 7 show the structures of the giant magnetoresistive elements 4i and 4j among the four giant magnetoresistive elements forming 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 cross-sectional view taken along the broken line IV-IV in FIG. 3, and FIG. 5 is surrounded by a broken line in FIG. FIG. 6 is a perspective view schematically showing an arrangement state of the band-like portion 5 and the bias magnet portion 6 of the giant magnetoresistive element.

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.

The groove 8 is an elongated recess having a depth of 3 μm to 8 μm and a length of 200 μm to 400 μm, and the slope has a width of 3 μm to 16 μm.
In addition, the slope of the groove 8 has first slopes 8A, 8E, 8G,... In the upper half and second slopes 8B, 8D, 8H,. The angle is different. In any case, the angle formed between the slope and the surface of the thick film 11 is 60 to 80 degrees, but the second slope is steeper than the first slope.
In FIG. 4, the first slope and the second slope of the groove are drawn as flat surfaces, but in actuality, they are curved surfaces that protrude slightly outward in the manufacturing process.

As shown in FIG. 5, the inclined surface of the groove 8 is, for example, an angle formed between the second inclined surface 8D and the silicon nitride film 34, that is, an angle formed between the second inclined surface 8D and the substrate 1 is θ. ₁ (0 ° <θ ₁ <90 °), the angle between the first inclined surface 8E and the silicon nitride film 34, that is, the angle formed between the first inclined surface 8E and the substrate 1 is θ ₂ (0 ° <0 If θ ₂ <90 °), the shape satisfies the relationship θ ₁ > θ ₂ .
And the strip | belt-shaped part 5 of a giant magnetoresistive element is provided in 2nd slope 8D with large angle | corner (theta) ₁ which the board | substrate 1 makes.
Thus, by providing the band-shaped portion 5 of the giant magneto-resistive element to the second inclined surface 8D angle theta ₁ is greater formed between the substrate 1, with uniform orientation of the sensitive axis of the Z-axis sensor, a high sensitivity It can be.

Of the eight slopes adjacent to each other in these grooves 8, 8, 8, 8, the second slope, which is the lower half, is along the longitudinal direction of the slope, and the flatness of the central portion of the slope is good. Eight giant magnetoresistive strips 5, 5, 5, 5 are provided at the positions.
Of these eight second slopes, one end of the strip 5 formed on the adjacent slope 8D from one end of the strip 5 formed on the slope 8B through the bottom 8C of the groove 8 A bias magnet portion 6 is provided and electrically connected.

Also, as shown in FIG. 3, one end of the strip 5 formed on the adjacent slope 8H so as to straddle the top 8F of the groove 8 from the other end of the strip 5 formed on the slope 8D. A bias magnet portion 6 is provided and electrically connected.
Furthermore, a bias magnet portion 6 is provided from the other end of the belt-like portion 5 formed on the slope 8H to one end of the belt-like portion 5 formed on the adjacent slope 8J through the bottom 8I of the groove 8; Electrically connected, one giant magnetoresistive element 4i is configured.
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 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.
The end portion of the wiring layer 7 can also function as a bias magnet portion.

  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 second slope and is directed upward. Further, the pinning direction of the belt-like 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-like portion 5. Parallel and upward on the second slope.

  On the other hand, in the giant magnetoresistive elements 4k and 4l forming the Z-axis sensor 4, the sensing axis is perpendicular to the longitudinal direction of the strip 5 (in the direction of the arrow in the figure), as shown in FIG. It is parallel to the second slope of the groove 8 and is directed downwardly of the second slope. Further, the pinning direction of the belt-like 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-like portion 5. Parallel and downward on the second slope.

  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.

  FIG. 8 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 7, 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. 9 shows an example of the structure of the via portion provided in the substrate 1. In FIG. 9, 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 second slope of the groove 8, and a magnetic sensor with 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.

(Magnetic sensor manufacturing method)
Next, an 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 second inclined surface of the grooves 8, 8,. To do.
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. 10A, 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. 10B, 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. 10C, a passivation film 32 is formed on the entire surface of the substrate 1. The passivation film 32 is formed by, for example, a plasma CVD (Chemical Vapor Deposition) method, and a silicon oxide film 33 having a thickness of 250 nm that forms a lower layer and a thickness of 600 nm that is formed by a plasma CVD method and forms an upper layer. A laminated film with the silicon nitride film 34 is used.

  Next, as shown in FIG. 10D, 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. 11A, 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. 11B, 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. 11C, the remaining resist film 36 is subjected to a heat treatment at a temperature of 150 ° C. for about 10 minutes to melt the resist film 36. By 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 as shown in the figure, and at the same time, the end surface becomes an inclined surface. 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, dry etching is performed on the resist film 36 and the thick film 35 under the condition that the etching selectivity between the resist and silicon oxide is approximately 1: 1.
The dry etching conditions are as follows.
For example, a mixed gas of CF ₄ / CHF ₃ / N ₂ / O ₂ = 60/180/10/100 is used, the gas pressure is 400 mT, the RF power is 750 W, and the electrode temperature is 15 ° C.

At the time of this dry etching, as shown in FIG. 12A, the opening area of the via part A and the pad part B is made not to be larger than the opening area of the passivation film 32.
Thereafter, the resist film 36 remaining on the thick film 35 is removed.

Accordingly, as shown in FIG. 12A, grooves 8, 8,... Are formed in the groove forming portion C of the thick film 35.
The slope of the groove 8 formed in the thick film 35 by dry etching as described above includes a second slope on the side of the continuous silicon nitride film 34 bent in the middle, and a first slope on the top side of the groove 8. It is made up of.

The inclined surface of the groove 8 has an angle formed between the second inclined surface and the silicon nitride film 34, that is, an angle formed between the second inclined surface and the substrate 1, with θ ₁ (0 ° <θ ₁ <90 °), When the angle between one slope and the silicon nitride film 34, that is, the angle between the first slope and the substrate 1 is θ ₂ (0 ° <θ ₂ <90 °), θ ₁ > θ ₂ It has a shape that satisfies the relationship.

Therefore, in the present invention, providing the strip portion 5 of the giant magneto-resistive element to the second slope is greater angle theta ₁ with the substrate 1.
The sizes of the angle θ ₁ and the angle θ ₂ vary depending on the etching conditions when forming the groove 8, but the size of the angle θ ₁ is desirably as large as possible, and is preferably close to 90 °.

Thus, by providing the band-shaped portion 5 of the giant magnetoresistive element an angle to the second slope theta ₁ is greater with substrate 1, with uniform orientation of the sensitive axis of the Z-axis sensor, it has high sensitivity and can do.

  Further, as shown in FIG. 12B, 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,... Are formed on the second slope, and simultaneously with this, a wiring film 25 is formed on the conductor part 21a of the via part A. The wiring film 25 and the giant magnetoresistive element A wiring layer 7 connecting the bias magnet unit 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.

  In order to appropriately etch the magnet film on the second inclined surface of the groove 8 during the resist work for forming the bias magnet portion 6, the resist film after pattern formation is subjected to heat treatment, It is preferable to make the end surface of this into 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 on the second slope of the grooves 8, 8,... As shown in FIG. The band-shaped parts 5, 5,... 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. 13B, 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. 13C, 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 providing the band-shaped portions 5, 5,... Of the giant magnetoresistive element film on the second inclined surface forming the inclined surfaces of the grooves 8, 8,. As a result, the magnetic sensor can be highly sensitive with the orientation of the sensing axis of the Z-axis sensor aligned.

  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 GMR in this invention. It is a schematic plan view which shows the example of GMR which comprises the Z-axis sensor in this invention. It is a schematic sectional drawing which shows the example of GMR which comprises the Z-axis sensor in this invention. It is an enlarged view of the part enclosed with the broken line of FIG. It is a schematic perspective view which shows the example of GMR which comprises the Z-axis sensor in this invention. It is a schematic perspective view which shows the other example of GMR which comprises the Z-axis sensor in this invention. It is explanatory drawing which shows the example of the connection method of GMR 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 one Embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows one Embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows one Embodiment of the manufacturing method of the magnetic sensor of this invention to process order. It is a schematic sectional drawing which shows one 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 Film 32... Passivation film 33. Silicon oxide film 34. Silicon nitride film 35 35 thick film 36 resist film

Claims (4)

An insulating film having a step forming portion formed on the substrate;
The insulating film is formed of a first inclined surface and a second inclined surface that is formed continuously with the first inclined surface and has a steeper angle with respect to the substrate surface than the first inclined surface. Ridges and grooves,
A magnetic sensor comprising: a magnetoresistive element disposed on the second slope. An insulating film is formed on the substrate,
The insulating film is etched to form a first slope and a second slope formed continuously with the first slope and having a steeper angle with respect to the substrate surface than the first slope. Forming ridges and grooves to be formed;
A method of manufacturing a magnetic sensor, comprising: forming a magnetoresistive element on the second slope and the flat surface of the insulating film. On the uppermost wiring layer of the substrate, a flattening layer that covers the wiring layer and forms a flat surface is formed, and after a passivation film is formed thereon,
A thick film is formed on this, and a resist film is further formed on this thick film.
Part of this resist film is removed, the remaining resist film is subjected to heat treatment, and the side surface of the resist film is formed as an inclined surface.
Next, the resist film and the thick film are etched under an etching condition in which the etching selectivity is approximately 1: 1 to form a groove in the thick film,
Next, the thick magnet flat surface, the second slope forming the slope of the groove, and the bias magnet part of the giant magnetoresistive element were formed on the top or bottom, and the giant magnetoresistive element film was formed thereon. After that, the substrate is placed on the magnet array and heat treated,
Next, a part of the giant magnetoresistive element film is removed by etching to form a band portion of the giant magnetoresistive element on the flat surface of the thick film and the second slope on the passivation film side of the slope of the groove. A method of manufacturing a magnetic sensor, comprising forming a protective film thereon. On the uppermost wiring layer of the substrate, a planarizing layer that covers the wiring layer and forms a flat surface is formed, and after forming a passivation film thereon,
A thick film is formed on this, a groove is formed in this thick film,
Next, the thick flat surface, the second slope forming the slope of the groove, and the bias magnet part of the giant magnetoresistive element are formed on the top or bottom, and the giant magnetoresistive element film is formed thereon. ,
Next, a part of the giant magnetoresistive element film is removed by etching to form a strip portion of the giant magnetoresistive element on the flat surface of the thick film and the first surface on the passivation film side of the slope of the groove. A method of manufacturing a magnetic sensor, comprising forming a protective film thereon.

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