JP2007273870A - Manufacturing method of thin film magnetic element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of manufacturing a thin film magnetic element with high reliability with simple steps. <P>SOLUTION: The manufacturing method of forming the thin film magnetic element 1 includes: an insulation layer forming step of forming an insulation layer 3 for covering a conductive film 20 patterned in a way that the conductive film 20 is provided on a base 5, and grooves 2 are formed; a magnetic film forming step of forming a magnetic film 41 on the insulation layer 3, and the insulation layer forming step includes the steps of forming a first insulator 31 made of a cured body of a thermosetting resin, and embedding at least part of the grooves 2 with a pattern for exposing at least part of a face S of the conductive film 20 opposite to the base 5; and forming a second insulator 32 for covering the first insulator 31 and the conductive film 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a thin film magnetic element having a conductive film and a magnetic film.

Conventionally, as a method of manufacturing an element having a wiring made of a conductive film patterned on a substrate and a functional film such as a magnetic film, an insulating layer is covered over the wiring to prevent leakage of the wiring. A method of forming a functional film is known (for example, Patent Document 1). On the other hand, techniques such as CMP (Chemical Mechanical Polishing) have been used to planarize the functional film of a thin film element (for example, Patent Documents 2 and 3).
Japanese Patent No. 3563709 Japanese Patent Laid-Open No. 11-67897 Japanese Patent Laid-Open No. 2001-44201

  When an insulating layer that covers the conductive film patterned so as to form a groove is formed, in many cases, a dent is generated on the surface of the insulating layer located above the groove. In particular, when an insulating layer is formed by application and curing of a curable resin, the surface tends to be easily dented due to curing shrinkage or the like.

  The magnetic film formed on the insulating layer having a recess formed on the surface is bent toward the inside of the groove along the recess of the insulating layer. If the magnetic film is bent in this way, there may arise a problem that the reliability of the obtained thin film magnetic element is lowered. For example, in the case of an inductor, it is desirable to reduce the distance between the conductive film and the magnetic layer in order to improve the inductance. However, if the thickness of the insulating layer between the conductive film and the magnetic film is reduced, insulation is reduced. There is a tendency for problems such as a decrease in inductance, deterioration in high-frequency characteristics, a decrease in DC superimposition characteristics, and the like due to the dents in the layer to become apparent.

  As a method of planarizing the insulating layer, a method of forming a sufficiently thick insulating layer and polishing it to a predetermined thickness that eliminates the surface dent by CMP or the like is conceivable. However, this method has a problem in that the production efficiency is reduced due to the addition of a polishing step and the manufacturing cost is increased due to the introduction of an expensive apparatus.

  Accordingly, an object of the present invention is to provide a manufacturing method that enables a highly reliable thin film magnetic element to be manufactured by a simple process.

  The present invention provides an insulating layer forming step of forming an insulating layer that covers a conductive film provided on a substrate and patterned so as to form a groove, and a magnetic film forming step of forming a magnetic film on the insulating layer. In the method of manufacturing a thin film magnetic element, the insulating layer forming step includes forming a first insulating portion made of a cured curable resin and filling at least a part of the groove on the side opposite to the base of the conductive film. Forming a pattern in which at least a part of the surface is exposed, and forming a second insulating portion that covers the first insulating portion and the conductive film.

  In the manufacturing method according to the present invention, the insulating layer covering the conductive film is divided into two stages: a first insulating part that fills the groove and a second insulating part that covers the conductive film together with the first insulating part. To form. By pre-filling the groove of the conductive film with the first insulating portion before forming the second insulating portion located on the magnetic film side, the depression of the surface of the insulating layer in the upper portion of the groove is suppressed, Or conversely, the surface of the insulating layer is raised, and the magnetic film formed on the insulating layer is prevented from bending toward the inside of the groove. As a result, it is possible to manufacture a highly reliable thin film magnetic element by a simple process without using a technique such as CMP.

  In the manufacturing method according to the present invention, it is preferable that the first insulating portion is formed so as to protrude from the conductive film in a direction opposite to the base. In this case, the surface of the second insulating portion is raised at the upper portion of the groove. As a result, the magnetic film is more reliably prevented from bending toward the inside of the groove.

  In the manufacturing method according to the present invention, it is preferable to form the first insulating portion so as to project on the surface of the conductive film opposite to the base. Also in this case, the magnetic film is more reliably prevented from bending toward the inside of the groove. Also, when a right angle or acute angle is formed between the surface of the conductive film opposite to the base and the wall surface of the groove, it tends to be difficult to maintain insulation by reliably covering this portion with an insulating layer. However, by forming the first insulating portion as described above, it becomes easy to maintain insulation even in such a case.

  According to the present invention, a highly reliable thin film magnetic element can be manufactured by a simple process. The present invention also has an advantage that the size of the distance between the conductive film and the magnetic film can be easily controlled by appropriately adjusting the thickness of the second insulating portion.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  FIG. 1 is a plan view showing an embodiment of a thin film magnetic element obtained by the manufacturing method according to the present invention, and FIG. 2 is a schematic sectional view taken along the line II-II in FIG. The thin film magnetic element 1 includes a base 5, a conductive film 20 provided on the base 5, an insulating layer 3 covering the conductive film 20, and a magnetic film 41 covering the insulating layer 3. The thin film magnetic element 1 is a thin film inductor including a conductive film 20 forming a coil pattern and a magnetic film 41.

  The base 5 is a laminated body in which the substrate 10, the lower magnetic film 40, and the lower insulating layer 30 are laminated in this order. A conductive film 20 is formed on the surface of the base 5 on the lower insulating layer 30 side.

  As the substrate 10, for example, a ferrite substrate composed of ferrite as a main component is used. In this case, the ferrite substrate functions as a substrate that supports the entire thin film magnetic element 1 and also functions as a magnetic layer for increasing the inductance. As a matter of course, a semiconductor wafer such as silicon or gallium arsenide, or ceramics such as alumina, glass, or silicon oxide can be used as the substrate 10.

  The lower magnetic film 40 is made of a soft magnetic metal magnetic material. Examples of the soft magnetic metal magnetic material include Co-based amorphous alloys such as CoZrTa-based alloys, CoZrNb-based alloys, and CoFeSiB-based alloys, and alloys mainly composed of FeSi, FeNi, Fe, and CoFe. Among these, a CoZrNb alloy or a CoZrTa alloy is preferable because the magnetostriction constant is low, high magnetic permeability, and high resistance are obtained. Furthermore, considering the direct current superposition characteristics of the inductor, a CoZrTa alloy having a large saturation magnetization is particularly preferable.

  The lower insulating layer 30 is provided mainly for maintaining insulation between the lower magnetic film 40 and the conductive film 20. The insulating material constituting the lower insulating layer 30 is not particularly limited, and the lower insulating layer 30 is formed of a cured body of ceramic or a curable resin.

  The conductive film 20 forms a spiral coil pattern on the substrate 5. An opening is formed in the insulating layer 3 and the magnetic film 41 so that the end 20T of the coil pattern of the conductive film 20 is exposed to the outside (FIG. 1). The thickness of the conductive film 20 is typically about 5 to 100 μm. The conductive film 20 is made of a conductor such as Cu. The shape, width, interval, number of turns, and the like of the coil pattern of the conductive film 20 can be appropriately changed according to required characteristics.

  The insulating layer 3 includes a first insulating portion 31 that fills the groove 2 formed by the conductive film 20 and the base 5, and a second insulating portion 32 that covers the first insulating portion 31 and the conductive film 20. It is configured. By interposing the insulating layer 3, the conductive film 20 and the magnetic film 41 are electrically insulated.

  The thickness of the first insulating portion 31 in the groove 2 is larger than the thickness of the conductive film 20. That is, the first insulating portion 31 is formed so as to protrude from the conductive film 20 in the direction opposite to the base 5. Further, the first insulating portion 31 projects on the surface S on the opposite side of the base of the conductive film 20. The first insulating portion 31 is formed by a cured body formed by curing a curable resin such as a thermosetting resin or a photosensitive resin. The first insulating part 31 is formed as a cured body of a photosensitive resin because it is easy to pattern so that the surface of the conductive film 20 opposite to the base 5 is exposed by photolithography. Is preferred. The curable resin for forming the first insulating portion 31 may further include other additive components such as a thermoplastic resin and a low molecular weight component in addition to a crosslinkable monomer such as an acrylic monomer and an oligomer.

  The second insulating portion 32 has a shape that rises at a portion located in the upper portion of the groove 2, reflecting the shape of the protruding portion of the first insulating portion 31. The second insulating portion 32 may be formed from a cured body of a curable resin similar to the first insulating portion 31 or may be formed from another insulating material such as ceramic.

  The magnetic film 41 reflects the shape of the second insulating portion 32 and has a shape bent in the direction opposite to the base 5 at the upper portion of the groove 2. In the case of the conventional manufacturing method, contrary to the present embodiment, the magnetic film tends to be bent in the direction toward the inside of the groove, thereby reducing the inductance, the high frequency characteristics, and the DC superposition characteristics. This has led to a decrease in reliability. On the other hand, according to the manufacturing method according to the present embodiment, the magnetic film 41 can be prevented from bending in the direction toward the inside of the groove 2. The magnetic film 41 is formed of a soft magnetic metal magnetic material having the same or different composition as the lower magnetic film 40. Examples of a method for forming the lower magnetic film made of the soft magnetic metal magnetic material include a sputtering method, a vapor deposition method, and a plating method. A high-frequency magnetic material layer having a laminated structure in which a soft magnetic metal magnetic material and a nonmagnetic insulator are formed on each other and suppressing eddy current loss can also be employed. The thickness of the magnetic film 41 is preferably 0.5 to 10 μm, depending on the device specifications, but is preferably 5 to 10 μm in the case of a power inductor and 0.5 to 1 μm in the case of a signal system. preferable.

  FIG. 3 is a schematic cross-sectional view showing an embodiment of a method for manufacturing a thin film magnetic element according to the present invention. In the manufacturing method shown in FIG. 3, first, a conductive film 20 patterned so as to form a coil pattern is formed on the surface of the base 5 on the lower insulating layer 30 side ((a) of FIG. 3). ).

  The base 5 is obtained, for example, by sequentially forming the lower magnetic film 40 and the lower insulating layer 30 on the substrate 10. The ferrite substrate used as the substrate 10 can be obtained by a conventionally known method. In general, a ferrite substrate cut into a predetermined shape and thickness from a sintered body obtained by a ceramic firing method is used. Ferrite substrates are also commercially available. The lower magnetic film 40 and the lower insulating layer 30 can be formed by a normal method such as a sputtering method or a paste method. As a matter of course, a semiconductor wafer such as silicon or gallium arsenide, or ceramics such as alumina, glass, or silicon oxide can be used as the substrate 10.

  The coil pattern of the conductive film 20 can be suitably formed by a method using photolithography. Specifically, for example, a seed layer made of a conductor is formed on one surface of the substrate 5 by a thin film process such as sputtering, and a photoresist pattern corresponding to the coil pattern is formed so that a predetermined portion thereof is exposed. The conductive film 20 is formed by forming a layer made of a conductor such as Cu on the exposed seed layer by plating, removing the photoresist pattern, and removing the exposed seed layer by etching. Can be made.

  After the formation of the conductive film 20, the first insulating portion 31 is projected in the direction opposite to the base in a pattern in which a part of the surface of the conductive film 20 opposite to the base 5 is exposed. In addition, the conductive film 20 is formed so as to protrude on the surface S opposite to the base 5. The first insulating part 31 is coated with a photosensitive resin as a curable resin so that the groove 2 is filled and the entire conductive film 20 is covered, and a curable resin layer (photosensitive resin layer) 31a is applied. A first insulation patterned so that a part of the surface opposite to the substrate 5 of the conductive film 20 is exposed by the step of forming (FIG. 3B) and the exposure and development of the curable resin layer 31a. It is formed through the step of forming the portion 31 (FIG. 3C).

  Subsequently, the second insulating portion 32 is formed so as to cover the first insulating portion 31 and the conductive film 20 ((d) in FIG. 3). Thereby, the insulating layer 3 which consists of the 1st insulating part 31 and the 2nd insulating part is formed. When the second insulating portion 32 is formed using a curable resin, the curable resin is applied so as to cover the first insulating portion 31 and the conductive film 20, and is cured by exposure, heating, or the like. Can be formed. When an inorganic insulating material such as silicon oxide is used, the second insulating portion 32 can be formed by a method such as a sputtering method or a CVD method.

  The thin film magnetic element 1 is obtained by forming the magnetic film 41 on the second insulating portion 32. The magnetic film 41 can be formed on the insulating layer 3 by a sputtering method, a vapor deposition method, a plating method or the like using a soft magnetic metal magnetic material.

  The present invention is not limited to the method of manufacturing a thin film inductor as in the above embodiment, and other thin film magnetic elements including a configuration in which a conductive film and a magnetic film, and an insulating layer interposed therebetween are provided. The method is also preferably employed.

It is a top view which shows one Embodiment of the thin film magnetic element obtained by the manufacturing method which concerns on this invention. It is a schematic sectional drawing along the II-II line of FIG. It is a schematic sectional drawing which shows one Embodiment of the manufacturing method of the thin film electronic element which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Thin film magnetic element, 2 ... Groove, 3 ... Insulating layer, 5 ... Base | substrate, 10 ... Substrate, 20 ... Conductive film, 30 ... Lower insulating layer, 31 ... 1st insulating part, 32 ... 2nd insulating part , 40: lower magnetic film, 41: magnetic film.

Claims (3)

A thin film comprising: an insulating layer forming step for forming an insulating layer covering a conductive film provided on a substrate and patterned so as to form a groove; and a magnetic film forming step for forming a magnetic film on the insulating layer A method of manufacturing a magnetic element,
The insulating layer forming step includes
Forming a first insulating portion made of a cured resin of a curable resin and filling at least a part of the groove in a pattern in which at least a part of the surface of the conductive film opposite to the base is exposed; ,
Forming a second insulating portion covering the first insulating portion and the conductive film;
Manufacturing method.   The manufacturing method according to claim 1, wherein the first insulating portion is formed so as to protrude from the conductive film in a direction opposite to the base.   The manufacturing method according to claim 1, wherein the first insulating portion is formed so as to protrude on a surface of the conductive film opposite to the base.

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