JP2001036017A - Inductor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance Q-value by increasing the inductance of a coil. SOLUTION: In a coil comprising first wiring 15, a contact hole 17 connected with this first wiring 15, and a second wiring 18 connected with this contact hole 17, the gap between the second wirings 18 is stopped with an oxide film 19a, and a wiring sidewall 19b is made at the sidewall of the second wiring 18 inside the coil, and a core part 20 adjoining this wiring sidewall 19b and consisting high permeability material is made within the coil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of an inductor in an analog circuit and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in the case of individually forming a solenoid type coil in a high frequency circuit, a large inductance is required in a small shape. Therefore, as shown in FIG. 13, a magnetic core inductor using a solenoid type coil 50 in which a magnetic core 52 is inserted into a coil 51 is used.

[0003] Such a solenoid type coil employs a core such as iron powder or ferrite, for example.
The magnetic permeability is higher than in the case of an air core. Therefore, the inductance per unit number of turns can be increased without changing the resistance R of the coil itself. Therefore, the Q value can be increased.

[0004]

When a coil is formed on a silicon wafer, a spiral coil 60 as shown in FIG. 14 has been studied.

[0005] The spiral type coil 60 shown in FIG.
As shown in FIG.
A mold well 62 is formed, and a first
Oxide film (not shown) is formed. A first wiring 63a is formed on the first oxide film, and the first wiring 63a is formed.
A second oxide film (not shown) is formed on a. A contact hole (not shown) is formed in the second oxide film,
The surface of one end of the first wiring 63a is exposed. next,
A wiring material is formed on the entire surface, the contact holes are buried and etched, and a spiral coil 60 including the second wiring 63b is formed on the second oxide film.

In such a spiral coil 60,
It is difficult to form a core having a high magnetic permeability as in the related art. Therefore, when a layer having a high magnetic permeability is formed on the entire surface to increase the inductance, the following problem occurs.

That is, since the layer having a high magnetic permeability is formed on the entire surface, the magnetic flux leaks without being shielded and affects other elements. Further, since the resistance between the windings forming the coil is reduced, one of the windings affects the other adjacent winding. For this reason, coil loss increases.

Therefore, the spiral coil 60 has a problem that the desired improvement of the Q value cannot be sufficiently obtained as in the solenoid coil 50.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an inductor capable of increasing the inductance of a coil and improving a Q value, and a method of manufacturing the same. It is in.

[0010]

The present invention uses the following means to achieve the above object.

An inductor according to the present invention comprises a conductive coil formed on an insulating film, a core defined on the insulating film at the center of the coil, and a high magnetic permeability formed on the core. Material, between the wires of the coil, a film formed of any of a low magnetic permeability material, a conductor, and an insulator, which is formed on the portion other than the core portion. Assuming that the inner diameter of the core portion is b and the thickness of the film at the core portion is x, the relationship a ≦ 2x ≦ b is satisfied.

Further, the inductor of the present invention comprises a conductive coil formed in an insulating film by a damascene process;
A core portion defined on a central portion of the coil on the insulating film; and a high magnetic permeability material formed in the core portion.

The high magnetic permeability material is formed at a predetermined distance from the wiring.

A film made of any of a low magnetic permeability material, a conductor, and an insulator is formed between the high magnetic permeability material and the wiring.

The high magnetic permeability material is formed so as to be contained in a resin film. Further, the high magnetic permeability material is Ni
-Fe alloy powder, or Co-Ti, Co-Zr, Co-
Either an amorphous film made of Hf or a ferrite-based MFe ₂ O ₄ film.

According to the method of manufacturing an inductor of the present invention, a step of forming a conductive coil on an insulating film, and a step of forming a high magnetic permeability material on a core portion defined on the insulating film and at the center of the coil. Forming a film made of any of a low-permeability material, a conductor, and an insulator in a region other than the core between the wirings of the coil on the insulating film. When the wiring interval of the coil is a, the inner diameter of the core portion is b, and the film thickness of the film at the core portion is x, the film is formed so as to satisfy the relationship a ≦ 2x ≦ b.

Further, a method of manufacturing an inductor according to the present invention comprises:
Forming a conductive film thicker than the depth of the concave portion on the concave portion formed by the insulating film, and selectively removing the conductive film;
Forming a coil by leaving the conductive film in the recess; and forming a high-permeability material on a core portion of the insulating film defined at the center of the coil.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] In a first embodiment of the present invention, as shown in FIG. 1, a first wiring 15 formed in a second oxide film 16 and a second oxide film A spiral inductor comprising a second wiring 18 formed on 16 is provided, and a central portion of the inductor has a core portion 20 made of a material having high magnetic permeability.

First, as shown in FIG. 2, an N-type well 12 is formed on a surface of, for example, a P-type semiconductor substrate 11, and an element isolation region 13 is formed on the N-type well 12. A first oxide film 14 is formed on the element isolation region 13,
On this first oxide film 14, for example, Al (aluminum)
The layer 15a is formed. On this Al layer 15a, a patterned resist film (not shown) is formed. The Al layer 15a is etched using the resist film as a mask, and the first wiring 15 is formed.

Next, a second oxide film 16 having a thickness of, for example, 2 μm is formed on the entire surface, and a patterned resist film (not shown) is formed on the second oxide film 16.
Using this resist film as a mask, second oxide film 16 is etched, and contact hole 17 is formed.

Next, a wiring material of, for example, Al is formed on the entire surface, and the contact holes 17 are buried. This wiring material is flattened, and the surface of the second oxide film 16 is exposed.

Next, for example, an Al layer 18a is formed on the entire surface, and a patterned resist film (not shown) is formed on the Al layer 18a. Using this resist film as a mask, Al layer 18a is etched, and second wiring 1
8 are formed. Here, the second wiring 1
The film thickness of 8 is, for example, 4 μm, the wiring width is, for example, 10 μm, the wiring interval a is, for example, 4 μm, and the inner diameter b of the coil is, for example, 200 μm.

Next, as shown in FIG.
The third oxide film 19 having a thickness of, for example, 2 μm is formed on the entire surface by the Al Vapor Deposition method. Here, the second
Of the wiring 18, the inner diameter b of the coil, the third oxide film 1
The film thickness x of 9 satisfies the relationship of the following expression (1).

A ≦ 2x ≦ b (1) Next, as shown in FIG. 4, RIE (Reactive Ion Etchi
ng), the third oxide film 19 is etched back,
Are filled with an oxide film 19a. A wiring side wall 19b is formed on the side wall of the second wiring 18 on the inner diameter side of the coil.

The wiring side wall 19b is not limited to an oxide film, but may be formed of, for example, a low magnetic permeability material, a conductive film, an insulating film, or the like. Further, a space may be formed on the side wall of the wiring instead of the oxide film, and the wiring side wall 19b may be in a vacuum state.

Next, as shown in FIG. 5, a resin film containing, for example, a Ni—Fe alloy powder as a magnetic material 20a having high magnetic permeability (high magnetic permeability material) is applied on the entire surface.
Here, the thickness of the high magnetic permeability material 20a is, for example, 4 μm. Note that the formation of the high magnetic permeability material 20a is not limited to coating,
For example, it may be performed by a sputtering method. The high magnetic permeability material 20a is made of Co—Ti, Co
An amorphous film such as -Zr or Co-Hf may be used, and a ferrite-based MFe ₂ O ₄ film may be used as the oxide thin film.

Next, as shown in FIG.
al Mechanical Polish), the high permeability material 20a is planarized, and the surface of the second wiring 18 is exposed. Thus, the core 20 of the inductor is formed on the second oxide film 16 inside the coil.

The method of flattening the high magnetic permeability material 20a is CM
The method is not limited to the P method, and may be etched back by RIE, for example.

In a region where the high magnetic permeability material 20a is unnecessary, a dummy wiring layer may be provided on the second oxide film 16 to prevent a magnetic field from being formed.

According to the first embodiment of the present invention, the core portion 20 embedded in the coil with the high magnetic permeability material 20a is used.
Is formed. For this reason, a large magnetic field can be generated inside the coil. Therefore, the inductance can be increased.

Since the oxide film 19a is buried between the wires of the coil, the high permeability material 20a is not formed between the wires. Therefore, a high resistance can be provided between the wirings of the coil. Accordingly, the loss of the coil can be suppressed.
Value can be improved.

Further, by setting the distance between the second wirings 18 to be equal to or less than the thickness of the third oxide film 19 to be filled, it is possible to prevent the high permeability material 20a from being formed on the wirings. For this reason, it becomes possible to shield well.
Therefore, the leakage of the magnetic flux can be prevented, and the influence on other elements can be suppressed.

By forming the wiring side wall 19b, it is possible to prevent the core portion 20 from being formed close to the wiring. For this reason, the skin effect by the magnetic field can be suppressed.

[Second Embodiment] Next, a second embodiment of the present invention will be described. In the second embodiment, the present invention is applied to an embedded wiring.

In the second embodiment of the present invention, as shown in FIG. 7, a first wiring 35 formed in a silicon oxide film 36 is formed.
And the second wiring 38 formed on the silicon oxide film 36
Is provided, and has a core portion 40 made of a high magnetic permeability material at the center of the inductor.

First, as shown in FIG. 8, an N-type well 32 is formed on the surface of, for example, a P-type semiconductor substrate 31, and an element isolation region 33 is formed on the N-type well 32. An oxide film 34 is formed on element isolation region 33.

Next, a silicon oxide film 35 is formed on the oxide film 34.
is formed, and a patterned resist film (not shown) is formed on the silicon oxide film 35a. Using this resist film as a mask, silicon oxide film 35a is etched to form wiring groove 35b. Next, a Cu layer 35c is formed on the entire surface, and the wiring groove 35b is buried. Thereafter, the Cu layer 35c is planarized by the CMP method, and the first wiring 35 is formed.

Next, as shown in FIG. 9, a silicon oxide film 36 is formed on the entire surface, and a patterned resist film (not shown) is formed on the silicon oxide film 36. Using this resist film as a mask, the silicon oxide film 36
Is etched to form a contact hole 37.

Next, a wiring material 37a of, for example, Cu is formed on the entire surface, and the contact holes 37 are buried. afterwards,
The wiring member 37a is planarized, and the surface of the silicon oxide film 36 is exposed.

Next, as shown in FIG. 10, a silicon oxide film 38a is formed on the entire surface.
On top, a patterned resist film (not shown) is formed. Using this resist film as a mask, silicon oxide film 38a is etched to form wiring groove 38b. Next, a Cu layer 38c is formed on the entire surface,
b is embedded. Then, the Cu layer 3 is formed by the CMP method.
8c is flattened and the second wiring 38 is formed, whereby a coil is formed.

Next, as shown in FIG. 11, a patterned resist film (not shown) is formed on the entire surface.
Using this resist film as a mask, the silicon oxide film 38a
Is removed, and a groove 39 is formed in the center of the coil. At this time, it is best that the silicon oxide film 38a is formed between the groove 39 and the second wiring 38.

Next, as shown in FIG.
For example, a Ni-Fe alloy powder is contained as the magnetic susceptibility material 40a.
The groove 39 is buried. In addition, high
The formation of the magnetic permeability material 40a is not limited to coating,
It may be performed by a cutter method. In addition, high permeability material
40a is Co-Ti, Co-Zr, C
An amorphous film such as o-Hf may be used.
Ferrite MFe _TwoO_FourIt may be a membrane.

Then, the high magnetic permeability material 4 is formed by the CMP method.
Oa is planarized, and the surfaces of the silicon oxide film 38a and the second wiring 38 are exposed. Thus, the core portion 40 of the inductor is formed in the silicon oxide film 38a inside the coil.

The method for removing the high magnetic permeability material 40a is CM
The method is not limited to the P method, and may be, for example, RIE. Further, the formation of the high magnetic permeability material 40a is not limited to after forming the coil, but can be performed before forming the coil. In this case, it is necessary to consider metal contamination of the high magnetic permeability material in the wiring forming step.

According to the second embodiment of the present invention, the core 40 embedded in the coil with the high magnetic permeability material 40a is used.
Is formed. For this reason, a large magnetic field can be generated inside the coil. Therefore, the inductance can be increased.

Further, the core portion 40 made of the high magnetic permeability material 40a can be formed only in a desired region such as the inside of the coil. For this reason, the high permeability material 4
0a is not formed, and the resistance between the coil wirings can be made high. Therefore, the loss of the coil can be suppressed.

Further, since the high magnetic permeability material 40a is not formed on the wiring, good shielding can be achieved.
Therefore, the leakage of the magnetic flux can be prevented, and the influence on other elements can be suppressed.

The groove 3 has a silicon oxide film 38a between the groove 39 and the second wiring 38 at the center of the coil.
By forming 9, the core portion 40 can be prevented from being formed close to the wiring. For this reason, the skin effect by the magnetic field can be suppressed.

In the second embodiment, since the coil is formed by the damascene process, it is easy to form the second wiring 38 with a large thickness. Therefore, since the resistance of the coil can be reduced, Q is further improved as compared with the first embodiment.
Value can be improved.

In the first embodiment, the high magnetic permeability material 20a may remain not only in the groove for forming the core portion 20 but also in the region where the depression exists. However, according to the second embodiment, the core unit 4
Since the groove 39 that becomes 0 can be selectively formed and the degree of freedom in forming the core portion is high, the high magnetic permeability material 40a can be left only in a desired region.

Further, in the first embodiment, when the coil itself becomes finer, the width between the wirings of the coil becomes further narrower,
Voids occur in the insulating film formed between the wirings. These voids cause the coil to be peeled off from the substrate due to a change in deposition due to a change in the temperature of the insulating film, and the voids are apt to leave etching residues, thereby causing a leak current between the wirings. As a result, not only may the inductor be reduced, but also the analog circuit itself may not operate. On the other hand, in the second embodiment, since the insulating film is formed before the coil is formed, a void-free insulating film is formed between the coil wires without being affected by the width between the coil wires. be able to.

The present invention is not limited to the first and second embodiments. For example, the first wiring is the second wiring
Although the first wiring is formed below the second wiring, the first wiring may be formed above the second wiring.

In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0055]

As described above, according to the present invention, it is possible to provide an inductor capable of increasing the inductance of a coil and improving the Q value, and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a plan view showing an inductor according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a manufacturing process of the inductor according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing the manufacturing process of the inductor following FIG. 2;

FIG. 4 is a sectional view showing the manufacturing process of the inductor following FIG. 3;

FIG. 5 is a sectional view showing the manufacturing process of the inductor following FIG. 4;

6 shows a step of manufacturing the inductor following FIG. 5, and FIG.
Sectional drawing along line 6-6 in FIG.

FIG. 7 is a plan view showing an inductor according to a second embodiment of the present invention.

FIG. 8 is a sectional view showing a manufacturing process of the inductor according to the second embodiment of the present invention.

FIG. 9 is a sectional view showing the manufacturing process of the inductor following FIG. 8;

FIG. 10 is a sectional view showing the manufacturing process of the inductor following FIG. 9;

FIG. 11 is a sectional view showing the manufacturing process of the inductor, following FIG. 10;

FIG. 12 is a sectional view showing a manufacturing step of the inductor following FIG. 11, and a sectional view taken along line 12-12 of FIG. 7;

FIG. 13 is a view showing a solenoid type coil.

FIG. 14 is a perspective view showing a spiral coil.

[Explanation of symbols]

 11, 31: semiconductor substrate, 12, 32: N-type well, 13, 33: element isolation region, 14, 34: first oxide film, 15a, 18a: Al layer, 15, 35: first wiring, 16 ... Second oxide film, 17, 37 ... Contact hole, 18, 38 ... Second wiring, 19 ... Third oxide film, 19a ... Oxide film, 19b ... Wiring side wall, 20a, 40a ... High permeability material, 20, 40: core portion, 35a, 36, 38a: silicon oxide film, 35b, 38b: wiring groove, 35c, 38c: Cu layer, 37a: wiring material, 39: groove.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Nobuo Hayasaka, Inventor No. 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 5E070 AA01 AB04 AB06 BA20 BB02 BB03 CB12 CB17 CB18 CB20 CC10 5F038 AZ04 CA02 EZ14 EZ15 EZ20

Claims (8)

[Claims] A conductive coil formed on an insulating film; a core portion defined on a central portion of the coil on the insulating film; a high magnetic permeability material formed on the core portion; A film made of any of a low-permeability material, a conductor, and an insulator, formed between the wirings of the coil and other than the core portion, wherein the wiring interval of the coil is a, and the inner diameter of the core portion is Where b is the thickness of the film at the core portion and x is a
An inductor characterized by satisfying a relationship of x ≦ b. 2. A conductive coil formed in an insulating film by a damascene process, a core defined on the insulating film at a center of the coil, and a high magnetic permeability material formed on the core. And an inductor. 3. The high-permeability material is formed at a predetermined distance from the wiring.
Or the inductor according to 2. 4. The inductor according to claim 1, wherein a film made of any of a low magnetic permeability material, a conductor, and an insulator is formed between the high magnetic permeability material and the wiring. . 5. The high-permeability material is formed so as to be contained in a resin film.
The inductor as described. 6. The high magnetic permeability material is a Ni—Fe alloy powder, an amorphous film made of any of Co—Ti, Co—Zr, Co—Hf, or a ferrite-based MF.
e ₂ O ₄ according to claim 1 to 5 inductor wherein a is any one of membrane. 7. A step of forming a conductive coil on an insulating film; a step of forming a high-permeability material on a core portion defined on a center portion of the coil on the insulating film; Forming a film made of any of a low-permeability material, a conductor, and an insulator in a region other than the core portion between wirings of the coil on an insulating film; a, when the inner diameter of the core portion is b and the thickness of the film in the core portion is x, a ≦ 2
A method of manufacturing an inductor, wherein the inductor is formed so as to satisfy a relationship of x ≦ b. 8. A step of forming a conductive film on a concave portion formed of an insulating film so as to be thicker than the depth of the concave portion, selectively removing the conductive film, and leaving the conductive film in the concave portion to form a coil. And a step of forming a high-permeability material on a core portion defined on a center portion of the coil on the insulating film.