JP2008224438A - Magnetic pressure sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic pressure sensor capable of performing reliable measurement of pressure. <P>SOLUTION: This magnetic pressure sensor comprises a glass substrate 11 having a main surface, a GMR (Giant MagnetoResistance) element 16 formed on the main face of the glass substrate 11 via an insulating layer 14, a wiring pattern 15 that is formed on the insulating layer 14 and is electrically connected with the GMR element 16, a silicon substrate 18 that is joined onto the insulating layer 14 so as to form a cavity 20 between it and the glass substrates 11 and has a diaphragm 18a having a hard magnetism layer 19 facing the GMR element 16, an extraction electrode 12 that is formed between the insulating layer 14 and the glass substrate 11 in a region including the joint region in the plan view and extracts the output of the GMR element 16 out of the cavity 20, and a conductive member 13 for electrically connecting the wiring pattern 15 to the extraction electrode 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic pressure sensor for detecting pressure using magnetic force and a method for manufacturing the same.

As a pressure sensor, a magnetic pressure sensor has been developed in which a magnetoresistive element is used instead of a fixed electrode of a capacitive pressure sensor, and a magnet is formed using a hard magnetic layer on the diaphragm side (Patent Document 1). . In this magnetic pressure sensor, a magnetoresistive effect element and a hard magnetic layer are disposed in a cavity formed by two substrates, and when a pressure is applied to the diaphragm, the diaphragm is deformed, thereby being provided in the diaphragm. The distance between the magnet formed using the hard magnetic layer and the magnetoresistive element changes. The change in the interval changes the magnetic field applied to the magnetoresistive effect element, and the change in pressure is detected using the change in magnetoresistance of the magnetoresistive effect element based on the change in magnetic field.
US Pat. No. 6,507,187

  However, in the above-described magnetic pressure sensor, when the output of the magnetoresistive effect element disposed in the cavity is taken out, a lead electrode is usually provided at the joint portion of the two substrates. In this case, since the extraction electrode is present at the joint portion between the two substrates, there is a problem that the airtightness in the cavity is lowered and the reliability of pressure measurement is lowered.

  This invention is made | formed in view of this point, and it aims at providing the magnetic type pressure sensor which can perform a reliable pressure measurement.

  The magnetic pressure sensor of the present invention is formed on a first substrate having a main surface, a magnetoresistive effect element formed on the main surface of the first substrate via an insulating layer, and the insulating layer. The wiring pattern electrically connected to the magnetoresistive effect element is joined to the insulating layer so as to form a cavity between the first substrate and the wiring pattern so as to face the magnetoresistive effect element. Formed between the second substrate having a diaphragm having a hard magnetic layer and the insulating layer in the region including the junction region in plan view, and the output of the magnetoresistive element in the cavity It is characterized by comprising a lead-out electrode led out and a conductive member for electrically connecting the wiring pattern and the lead-out electrode.

  According to this configuration, since the output of the magnetoresistive effect element is drawn out of the cavity without using the junction region between the insulating layer and the second substrate, airtightness in the cavity can be ensured, Thereby, the reliability of pressure measurement can be improved.

  In the magnetic pressure sensor according to the present invention, the extraction electrode includes a wiring layer and a pair of barrier layers that sandwich the wiring layer, and the conductive member and the wiring layer are electrically connected to each other. It is preferable that

  In the magnetic pressure sensor of the present invention, it is preferable that the extraction electrode is electrically connected to the electrode pad by a conductive member outside the cavity.

  The method of manufacturing a magnetic pressure sensor according to the present invention includes a step of forming an extraction electrode on a main surface of a first substrate, a step of standing a columnar conductive member on the extraction electrode, and embedding the conductive member. Forming an insulating layer on the first substrate, planarizing the insulating layer to expose the conductive member, forming a magnetoresistive element on the insulating layer, the conductive member, and the magnetic layer Forming a wiring pattern on the insulating layer so as to be electrically connected to the resistance effect element; forming a diaphragm having a hard magnetic layer on the second substrate; and the magnetoresistance effect element and the hard magnetic layer Bonding the second substrate to the insulating layer so as to face each other.

  According to this method, the airtightness in the cavity can be ensured, whereby a magnetic pressure sensor with improved pressure measurement reliability can be obtained. Further, according to this method, since the magnetoresistive effect element is formed after the insulating layer is flattened, the distance between the magnetoresistive effect element and the hard magnetic layer can be accurately ensured, and pressure measurement is performed. Can improve the reliability.

  According to the magnetic pressure sensor of the present invention, a first substrate having a main surface, a magnetoresistive effect element formed on the main surface of the first substrate via an insulating layer, and formed on the insulating layer. And is bonded to the insulating layer so as to form a cavity between the wiring pattern electrically connected to the magnetoresistive effect element and the first substrate, and is opposed to the magnetoresistive effect element. Formed between the second substrate having a diaphragm having a hard magnetic layer and the insulating layer in the region including the junction region in plan view and the output of the magnetoresistive element. Since the lead-out electrode led out of the cavity and a conductive member that electrically connects the wiring pattern and the lead-out electrode are provided, the air in the cavity where the magnetoresistive effect element and the hard magnetic layer are disposed is provided. Can be kept high sex, it is possible to perform pressure measurements while maintaining a high reliability.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a magnetic pressure sensor according to an embodiment of the present invention. FIG. 2 is a plan view of the magnetic pressure sensor according to the embodiment of the present invention.

  A magnetic pressure sensor 1 shown in FIG. 1 has a glass substrate 11 as a base substrate. Examples of the base substrate include an alumina substrate, a silicon substrate, an LTCC substrate (low temperature fired ceramic substrate), an HTCC substrate (high temperature fired ceramic substrate), etc. On one main surface of the glass substrate 11, A lead electrode 12 is formed to draw out the output of a magnetoresistive effect element, which will be described later, out of the cavity 20. This lead electrode 12 is a glass corresponding to a bonding region A between the silicon substrate 18 as a second substrate to be described later. The lead electrode 12 is formed over a region on the substrate 11. The lead electrode 12 functions to pull out the output of the magnetoresistive effect element disposed in the cavity 20 to the outside of the cavity 20, and therefore, glass corresponding to at least the junction region A. It may be formed in the region on the substrate 11.

  An insulating layer 14 is formed on the glass substrate 11 and the extraction electrode 12. Therefore, the extraction electrode 12 is formed between the insulating layer 14 and the glass substrate 12. Examples of the material constituting the insulating layer 14 include alumina and silicon oxide. In a region in the cavity 20 on the insulating layer 14, a GMR (Giant MagnetoResistance) element 16 as a magnetoresistive effect element and a wiring pattern 15 electrically connected to the GMR element 16 are formed. Therefore, the GMR element 16 is formed on the glass substrate 11 via the insulating layer 14 in a region within the cavity 20 within the cavity 20. An electrode pad 17 that is a bonding pad is formed in a region outside the cavity 20 on the insulating layer 14.

  A conductive member 13 that electrically connects the wiring pattern 15 and the lead electrode 12 is embedded in the insulating layer 14 in the cavity 20, and an electrode is formed in the insulating layer 14 outside the cavity 20. The conductive member 13 that electrically connects the pad 17 and the extraction electrode 12 is embedded. Thus, the GMR element 16 and the wiring pattern 15 are electrically connected in the cavity 20, the wiring pattern 15 and the conductive member 13 are electrically connected, and the conductive member 13 and the bonding region A are connected to each other. The extending lead electrode 12 is electrically connected in the insulating layer 14, the conductive member 13 and the lead electrode 12 are electrically connected outside the cavity 20, and the conductive member 13 and the electrode pad 17 are electrically connected. Therefore, the GMR element 16 is connected to the wiring pattern 15, the conductive member 13 embedded in the insulating layer 14, and the lead-out so that the GMR element 16 does not come into contact with the silicon substrate 18 in the junction region A with the silicon substrate 18. The electrode 12 is electrically connected to the electrode pad 17 outside the cavity 20. As shown in FIG. 2, the conductive member 13 is electrically connected along the vertical direction by the conductive member 13 penetrating the insulating layer 14 in a region where the wiring pattern 15 and the extraction electrode 12 overlap in a plan view. They are electrically connected along the vertical direction by a conductive member 13 that penetrates the insulating layer 14 in a region where the electrode pad 17 and the extraction electrode 12 overlap. Examples of the material constituting the conductive member 13 include metals such as silicon, Cu, Ni, and Au. In addition, by using Au as the material constituting the conductive member 13, the conductive member 13 exposed in the insulating layer 14 can be used as a bonding pad without providing the electrode pad 17, and wire bonding of Au wire can be performed with the conductive member. 13 can be done directly. In FIG. 2, reference numeral 21 indicates a fixed resistor.

  The lead electrode 12 in the X part in FIG. 1 preferably has, for example, the configuration shown in FIG. That is, the lead electrode 12 is configured by a wiring layer 122 and a pair of barrier layers 121 and 123 that sandwich the wiring layer 122, and the conductive member 13 and the wiring layer 122 are electrically connected. preferable. Examples of the material constituting the wiring layer 122 include Cu and Au, and examples of the material constituting the barrier layers 121 and 123 include Cr and Ti. For example, examples of combinations of the wiring layer 122 and the barrier layers 121 and 123 include Cr / Cu / Cr, Ti / Cu / Ti, Ti / Au / Ti, and Cr / Au / Au.

A silicon substrate 18 is bonded on the insulating layer 14 so as to form a cavity 20 with the glass substrate 11. In the bonding between the insulating layer 14 and the silicon substrate 18, it is preferable that the heating temperature is about 300 or less in consideration of the heat resistant temperature of the GMR element 16. Further, by forming a layer made of SiO ₂ or the like in the bonding region A between the insulating layer 14 and the silicon substrate 18 and activating the surface, the insulating layer 14 and the silicon substrate can be bonded at a relatively low temperature. The joint strength between the two can be improved.

  The silicon substrate 18 has a diaphragm 18 a having a hard magnetic layer 19 that is a magnet at a position facing the GMR element 16. Examples of the material constituting the hard magnetic layer 19 include a CoPt alloy and a CoCrPt alloy. Thus, the insulating layer 14 and the silicon substrate 18 are joined to form a cavity 20 between the insulating layer 14 and the silicon substrate 18. The GMR element 16 and the hard magnetic material 16 are opposed to each other in the cavity 20. Layer 19 is disposed. Thereby, a magnetic field can be applied to the GMR element 16.

  As shown in FIG. 4, the GMR element 16 includes an antiferromagnetic layer 161 made of IrMn, PtMn, or the like, and a pinned magnetic layer made of a ferromagnetic material, such as NiFe or CoFe, on the insulating layer 14 in order from the bottom. 162, a non-magnetic material layer 163 made of Cu or the like and a free magnetic layer 164 made of a ferromagnetic material such as NiFe or CoFe. In the form shown in FIG. 4, a seed layer 165 made of NiFeCr or Cr is provided under the antiferromagnetic layer 161 to adjust the crystal orientation, but the seed layer 165 is not essential.

  A protective layer 166 made of Ta or the like is formed on the free magnetic layer 164. In the GMR element 16, since the antiferromagnetic layer 161 and the pinned magnetic layer 162 are formed in contact with each other, the interface between the antiferromagnetic layer 161 and the pinned magnetic layer 162 is exchanged by performing a heat treatment in a magnetic field. A coupling magnetic field (Hex) is generated, and the magnetization direction 162a of the pinned magnetic layer 162 is pinned in one direction. In FIG. 4, the magnetization direction 162a is fixed in the X1 direction shown.

  On the other hand, the magnetization direction 164a of the free magnetic layer 164 is aligned antiparallel to the magnetization direction 162a of the pinned magnetic layer 162, for example, in the form of FIG. That is, the magnetization direction 164a is oriented in the X2 direction shown in the drawing. The free magnetic layer 164 is not magnetization fixed like the pinned magnetic layer 162, and its magnetization direction varies with an external magnetic field.

  When a horizontal magnetic field H directed in a direction parallel to the film surface of each layer constituting the magnetoresistive effect element in the external magnetic field generated from the hard magnetic layer 19 acts in the X1 direction shown in FIG. 4, the free magnetic layer 164 The magnetization direction 164a of the magnetic layer 162 fluctuates, and the electrical resistance changes depending on the relationship between the magnetization direction 162a of the pinned magnetic layer 162 and the magnetization direction 164a of the free magnetic layer 164. This is called a spin valve type Giant MagnetoResistance effect. In order to develop the giant magnetoresistive effect, the antiferromagnetic layer 161, the fixed magnetic layer 162, the nonmagnetic material layer 163 and the free magnetic layer as described above are used. A four-layer basic structure of the magnetic layer 164 is required. Further, as the magnetoresistive effect element, a tunnel magnetoresistive (TMR) element having a tunnel magnetoresistive effect may be used instead of the GMR element 16. In the case of the TMR element, the nonmagnetic material layer 163 is replaced with a nonmagnetic insulating material such as aluminum oxide or magnesium oxide which is a material of the tunnel barrier.

  As shown in FIG. 2, the two GMR elements 16 described above are formed side by side, and the magnetization direction of the pinned magnetic layer 162 of the GMR element 16 is the same as that of the two GMR elements. Further, as shown in FIG. 2, the GMR elements 16 are connected by a wiring pattern via a fixed resistor 21 to form a so-called bridge circuit. In this case, for example, one of the conductive members 13a can be GND, a power supply voltage can be applied between the conductive members 13a-13a, and the output voltage between the conductive members 13b-13b can be used as the output of the magnetic pressure sensor.

  In the magnetic pressure sensor having such a configuration, a magnetic field is applied to the GMR element 16 by the hard magnetic layer 19. When pressure is applied to the diaphragm 18a, the diaphragm 18a moves according to the pressure. Thereby, the diaphragm 18a is displaced, and the distance between the hard magnetic layer 19 and the GMR element 16 is changed. At this time, the magnetic field applied to the GMR element 16 changes. Therefore, the change in magnetic resistance of the GMR element 16 based on the change in the magnetic field can be used as a parameter, and the change can be used as a pressure change.

  In this magnetic pressure sensor, since the output of the GMR element 16 is drawn out of the cavity 20 without using the junction region A between the insulating layer 14 and the silicon substrate 18, airtightness in the cavity 20 is ensured. This can increase the reliability of pressure measurement.

  Next, a method for manufacturing the magnetic pressure sensor of the present embodiment will be described. FIGS. 5A to 5C and FIGS. 6A to 6E are views for explaining a method for manufacturing a magnetic pressure sensor according to an embodiment of the present invention.

  In the magnetic pressure sensor of the present invention, a lead electrode 12 is formed on the main surface of the glass substrate 11, a columnar conductive member 13 is erected on the lead electrode 12, and the conductive member 13 is embedded on the glass substrate. An insulating layer 14 is formed on the insulating layer 14, the insulating layer 14 is planarized to expose the conductive member 13, a GMR element 16 is formed on the insulating layer 14, and the conductive member 13 and the GMR element 16 are electrically connected. A wiring pattern 15 is formed on the layer 14, a diaphragm 18a having a hard magnetic layer 19 is formed on the silicon substrate 18, and the silicon substrate 18 is bonded to the insulating layer 14 so that the GMR element 16 and the hard magnetic layer 19 face each other. To do.

  As shown in FIG. 5A, the extraction electrode 12 is formed in a region including the bonding region of one main surface of the glass substrate 11. The extraction electrode 12 is formed by depositing an electrode material on the glass substrate 11 by sputtering or the like, and performing photolithography and etching. Next, in plan view, the conductive member 13 is erected in the region of the extraction electrode 12 where the extraction electrode 12 overlaps the wiring pattern 15 and the electrode pad 17. The conductive member 13 is formed by a method such as plating. Next, as illustrated in FIG. 5B, an insulating layer 14 is formed on the glass substrate 11 so as to embed the conductive member 13. The insulating layer 14 is formed by a method such as sputtering. Next, as shown in FIG. 5C, the insulating layer 14 is planarized by CMP (Chemical Mechanical Polishing) to expose the conductive member 13. As a result, contact portions of the wiring pattern 15 and the conductive pads 17 are formed. By flattening the insulating layer 14 in this way, the interval between the GMR element 16 and the hard magnetic layer 19 can be ensured accurately, and the reliability of pressure measurement can be improved.

  Here, a detailed process for manufacturing the structure shown in FIG. 5C will be described. First, as illustrated in FIG. 6A, a barrier layer 121, a wiring layer 122, and a barrier layer 123 are stacked on the glass substrate 11. This laminated film is formed by sputtering the material constituting each layer. Next, as shown in FIG. 6B, an opening 123 a is formed in the upper barrier layer 123 to expose the wiring layer 122 so that the wiring layer 122 and the conductive member 13 are brought into contact with each other. In this case, the opening 123a is formed by performing photolithography and etching.

  Next, as shown in FIG. 6C, a plating resist layer 22 is formed on the glass substrate 11 on which the extraction electrode 12 is formed, and an opening 22a is formed in a region including the region where the wiring layer 122 is exposed by photolithography. Form. Next, as shown in FIG. 6D, the conductive member 13 is formed on the wiring layer 122 by plating using the resist layer 22 as a mask. Thereafter, after removing the resist layer 22, as shown in FIG. 6E, the insulating layer 14 is formed on the glass substrate 11 so as to embed the conductive member 13. Next, the insulating layer 14 is planarized by CMP to expose the conductive member 13.

  Next, the GMR element 16 is formed on the insulating layer 14 in the cavity forming region. The GMR element 16 is formed by sputtering or lift-off, for example. Next, a wiring pattern 15 is formed on the insulating layer 14 in the cavity forming region so as to be electrically connected to the GMR element 16. The wiring 15 is formed by depositing a wiring material on the insulating layer 14 by sputtering or the like, and performing photolithography and etching. Next, an electrode pad 17 is formed on the insulating layer 14 outside the cavity so as to be electrically connected to the conductive member 13. The electrode pad 17 is formed by depositing an electrode material on the insulating layer 14 and performing photolithography and etching.

  Next, a magnet (hard magnetic layer) 19 made of a hard magnetic layer is formed on the bottom surface of the diaphragm concave portion of the silicon substrate 18. The hard magnetic layer 19 is formed by depositing a hard magnetic material on the silicon substrate 18 and performing photolithography and etching. Thereafter, the silicon substrate 18 is polished to form a diaphragm 18a having a predetermined thickness of about several tens of μm.

  Next, the silicon substrate 18 is placed on the insulating layer 14 side and the silicon substrate 18 is bonded onto the insulating layer 14 so that the hard magnetic layer 19 is positioned at a predetermined distance from the GMR element 16. In this way, the magnetic pressure sensor having the configuration shown in FIG. 1 is manufactured.

  In the magnetic pressure sensor thus obtained, the airtightness in the cavity can be ensured, thereby improving the reliability of pressure measurement. Further, according to the above method, since the GMR element 16 is formed after the insulating layer 14 is flattened, the interval between the GMR element 16 and the hard magnetic layer 19 can be accurately ensured. , Can improve the reliability of pressure measurement.

  The present invention is not limited to the embodiment described above, and can be implemented with various modifications. For example, the element structure, dimensions, and materials described in the above embodiment are not particularly limited. Further, the process described in the above embodiment is not limited to this, and the process may be performed by changing the order as appropriate. Other modifications may be made as appropriate without departing from the scope of the object of the present invention.

It is sectional drawing which shows the magnetic type pressure sensor which concerns on embodiment of this invention. It is a top view which shows the magnetic type pressure sensor which concerns on embodiment of this invention. It is an enlarged view which shows the X section of the magnetic type pressure sensor shown in FIG. It is a figure for demonstrating a GMR element. (A)-(c) is a figure for demonstrating the manufacturing method of the magnetic-type pressure sensor which concerns on embodiment of this invention. (A)-(e) is a figure for demonstrating the manufacturing method of the magnetic type pressure sensor which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Glass substrate 12 Lead electrode 13, 13a, 13b Conductive member 14 Insulating layer 15 Wiring pattern 16 GMR element 17 Electrode pad 18 Silicon substrate 18a Diaphragm 19 Magnet formed with hard magnetic layer 20 Cavity 21 Fixed resistance 22 Resist layer 22a, 123a Opening Part 121, 123 Barrier layer 122 Wiring layer

Claims (4)

  A first substrate having a main surface, a magnetoresistive effect element formed on the main surface of the first substrate via an insulating layer, and formed on the insulating layer, electrically connected to the magnetoresistive effect element A diaphragm having a hard magnetic layer so as to be opposed to the magnetoresistive element and bonded to the insulating layer so as to form a cavity between the wiring pattern connected to the first substrate and the first substrate A lead electrode formed between the second substrate, the insulating layer in a region including the bonding region in plan view, and the first substrate, and pulling out an output of the magnetoresistive effect element out of the cavity; and the wiring A magnetic pressure sensor comprising: a conductive member that electrically connects a pattern and the extraction electrode.   The lead electrode is constituted by a wiring layer and a pair of barrier layers sandwiching the wiring layer, and the conductive member and the wiring layer are electrically connected. The magnetic pressure sensor according to 1.   The magnetic pressure sensor according to claim 1, wherein the lead electrode is electrically connected to the electrode pad by a conductive member outside the cavity.   Forming an extraction electrode on the main surface of the first substrate; erecting a columnar conductive member on the extraction electrode; and forming an insulating layer on the first substrate so as to embed the conductive member. Flattening the insulating layer to expose the conductive member; forming a magnetoresistive element on the insulating layer; and electrically connecting the conductive member and the magnetoresistive element to each other. Forming the wiring pattern on the insulating layer; forming a diaphragm having a hard magnetic layer on the second substrate; and setting the second substrate so that the magnetoresistive element and the hard magnetic layer face each other. And a step of bonding to the insulating layer.

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