Thin film coil, method of manufacturing the same, coil structure, and method of manufacturing the same

• US 20060001520A1
• Filed: 06/21/2005
• Published: 01/05/2006
• Est. Priority Date: 07/01/2004
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Kamijima, Akifumi, Takeo, Kenji, Aoki, Susumu, Sato, Yoshikazu, Kaji, Rina
• Granted Patent: US 7,307,503 B2
• Time in Patent Office: Days
• US Class Current: 336/223
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01F 2017/0093 Common mode choke coil
• CPC Class Codes: H01F 27/34 Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
• CPC Class Codes: H01F 41/041 Printed circuit coils apparatus or processes for manufacturing printed circuits in general H05K3/00
• CPC Class Codes: H01L 28/10 Inductors

Abstract

The present invention provides a coil structure capable of improving a differential transmission characteristic by reducing capacitance as much as possible. A common mode choke coil is constructed so that a section of each of two coil patterns constructing a thin film coil has an inverted trapezoid shape which is bilaterally asymmetrical. Because of the structural characteristic that the section of each of the two coil patterns has an inverted trapezoid shape which is bilaterally asymmetrical, the facing area of the two coil patterns contributing to capacitance is minimized. Thus, the capacitance of the thin film coil can be reduced as much as possible.

Claims

1. A thin film coil including a first coil pattern and a second coil pattern which are provided on a predetermined underlayer and turn spirally in parallel with each other around a predetermined center position,

wherein each of a section of the first coil pattern and a section of the second coil pattern has a trapezoid shape having one side positioned on the side far from the underlayer and specifying two base angles as a longer one of a set of opposite sides which are parallel to each other and the other side positioned on the side close to the underlayer as a shorter one of the set of opposite sides.

2. A thin film coil according to claim 1,

wherein a shape of the section of the first coil pattern and a shape of the section of the second coil pattern match each other in an arbitrary turn position.

3. A thin film coil according to claim 2,

wherein a first inner-side base angle positioned on the side close to the center position and a first outer-side base angle positioned on the side far from the center position out of the two base angles are different from each other in the section of the first coil pattern, and

a second inner-side base angle positioned on the side close to the center position and a second outer-side base angle positioned on the side far from the center position out of the two base angles are different from each other in the section of the second coil pattern.

4. A thin film coil according to claim 3,

wherein the first outer-side base angle is larger than the first inner-side base angle in the section of the first coil pattern, and

the second outer-side base angle is larger than the second inner-side base angle in the section of the second coil pattern.

5. A thin film coil according to claim 1, wherein a shape of the section of the first coil pattern and a shape of the section of the second coil pattern are different from each other in an arbitrary turn position.

6. A thin film coil according to claim 5, wherein

a first inner-side base angle positioned on the side close to the center position and a first outer-side base angle positioned on the side far from the center position out of the two base angles match each other in the section of the first coil pattern, and

a second inner-side base angle positioned on the side close to the center position and a second outer-side base angle positioned on the side far from the center position out of the two base angles match each other in the section of the second coil pattern.

7. A coil structure in which a thin film coil is buried between two magnetic substrates via an insulating layer,

wherein the thin film includes a first coil pattern and a second coil pattern which are provided on a predetermined underlayer and turn spirally in parallel with each other around a predetermined center position, and

each of a section of the first coil pattern and a section of the second coil pattern has a trapezoid shape having one side positioned on the side far from the underlayer and specifying two base angles as a longer one of a set of opposite sides which are parallel to each other and the other side positioned on the side close to the underlayer as a shorter one of the set of opposite sides.

8. A method of manufacturing a thin film coil including a first coil pattern and a second coil pattern which are provided on a predetermined underlayer and turn spirally in parallel with each other around a predetermined center position,

wherein a process of forming the first and second coil patterns comprises:

a first step of forming a photoresist on the underlayer;

a second step of forming a photoresist pattern by selectively exposing and patterning the photoresist while controlling progress in an exposing process so that the photoresist pattern has a first opening for forming the first coil pattern and a second opening for forming the second coil pattern and each of width of the first opening and width of the second opening gradually decreases toward the underlayer;

a third step of forming the first and second coil patterns in the first and second openings, respectively, in the photoresist pattern so that each of a section of the first coil pattern and a section of the second coil pattern has a trapezoid shape including one side which is positioned on the side far from the underlayer and specifies two base angles as a longer one of a set of opposite sides which are parallel to each other and the other side positioned on the side close to the underlayer as a shorter one of the set of opposite sides; and

a fourth step of removing the used photoresist pattern.

9. A method of manufacturing a thin film coil according to claim 8,

wherein the first and second coil patterns are formed so that a shape the section of the first coil pattern and a shape of the section of the second coil pattern match each other in an arbitrary turn position.

10. A method of manufacturing a thin film coil according to claim 9,

wherein out of the two base angles, the first coil pattern is formed so that a first inner-side base angle positioned on the side close to the center position and a first outer-side base angle positioned on the side far from the center position are different from each other in the section of the first coil pattern, and

out of the two base angles, the second coil pattern is formed so that a second inner-side base angle positioned on the side close to the center position and a second outer-side base angle positioned on the side far from the center position are different from each other in the section of the second coil pattern.

11. A method of manufacturing a thin film coil according to claim 10,

wherein the first coil pattern is formed so that the first outer-side base angle is larger than the first inner-side base angle in the section of the first coil pattern, and

the second coil pattern is formed so that the second outer-side base angle is larger than the second inner-side base angle in the section of the second coil pattern.

12. A method of manufacturing a thin film coil according to claim 8, wherein the first and second coil patterns are formed so that a shape of the section of the first coil pattern and a shape of the section of the second coil pattern are different from each other in an arbitrary turn position.

13. A method of manufacturing a thin film coil according to claim 12, wherein, the first coil pattern is formed so that a first inner-side base angle positioned on the side close to the center position and a first outer-side base angle positioned on the side far from the center position out of the two base angles match each other in the section of the first coil pattern, and

the second coil pattern is formed so that a second inner-side base angle positioned on the side close to the center position out of the two base angles and a second outer-side base angle positioned on the side far from the center position out of the two base angles match each other in the section of the second coil pattern.

14. A method of manufacturing a thin film coil including a first coil pattern and a second coil pattern which are provided on a predetermined underlayer and turn spirally in parallel with each other around a predetermined center position,

wherein a process of forming the first and second coil patterns comprises:

a first step of, on the underlayer on which a photoresist pattern having a first inner frame part and a first outer frame part disposed so as to face each other, thereby defining a first opening for forming the first coil pattern, and a second inner frame part and a second outer frame part disposed so as to face each other, thereby defining a second opening for forming the second coil pattern is to be formed, patterning a first exposure control layer for controlling progress of an exposing process so as to be formed in either a first inner area which is positioned on the side close to the center position and in which the first inner frame part is to be formed or a first outer area which is positioned on the side far from the center position and in which the first outer frame part is to be formed, and patterning a second exposure control layer for controlling progress of the exposing process so as to be formed in either a second inner area which is positioned on the side close to the center position and in which the second inner frame part is to be formed or a second outer area which is positioned on the side far from the center position and in which the second outer frame part is to be formed;

a second step of forming a photoresist so as to cover the underlayer, the first exposure control layer, and the second exposure control layer;

a third step of forming the first and second openings by patterning the photoresist by selective exposure, thereby forming the photoresist pattern on the underlayer so that the photoresist pattern has the first inner frame part disposed in the first inner area, the first outer frame part disposed in the first outer area, the second inner frame part disposed in the second inner area, and the second outer frame part disposed in the second outer area, width of each of the first opening and the second opening gradually decreases toward the underlayer, an inclination angle of a first inner-side defining face defining the first opening in the first inner frame part and an inclination angle of a first outer-side defining face defining the first opening in the first outer frame part are different from each other, and an inclination angle of a second inner-side defining face defining the second opening in the second inner frame part and an inclination angle of a second outer-side defining face defining the second opening in the second outer frame part are different from each other;

a fourth step of forming the first and second coil patterns in the first and second openings, respectively, in the photoresist pattern so that each of a section of the first coil pattern and a section of the second coil pattern has a trapezoid shape including one side which is positioned on the side far from the underlayer and specifies two base angles as a longer one of a set of opposite sides which are parallel to each other and the other side positioned on the side close to the underlayer as a shorter one of the set of opposite sides, and a shape of the section of the first coil pattern and a shape of the section of the second coil pattern become the same; and

a fifth step of removing the photoresist pattern and the first and second exposure control layers used.

15. A method of manufacturing a thin film coil according to claim 14, wherein, in the first step, a reflection suppression layer for suppressing a reflection phenomenon at the time of exposure is formed as each of the first and second exposure control layers.

16. A method of manufacturing a thin film coil according to claim 15, wherein the reflection suppression layer is formed in both of the first and second outer areas in the first step,

the photoresist pattern is formed so that the inclination angle of the first outer-side defining face becomes larger than the inclination angle of the first inner-side defining face, and the inclination angle of the second outer-side defining face becomes larger than the inclination angle of the second inner-side defining face in the third step, and

the first coil pattern is formed so that a first outer-side base angle as one of the two base angles positioned on the side far from the center position becomes larger than a first inner-side base angle positioned on the side close to the center position in the section of the first coil pattern, and the second coil pattern is formed so that a second outer-side base angle as one of the two base angles positioned on the side far from the center position becomes larger than a second inner-side base angle positioned on the side close to the center position in the section of the second coil pattern in the fourth step.

17. A method of manufacturing a thin film coil according to claim 14, wherein, in the first step, a reflection promotion layer for promoting a reflection phenomenon at the time of exposure is formed as each of the first and second exposure control layers.

18. A method of manufacturing a thin film coil according to claim 17, wherein the reflection promotion layer is formed in both of the first and second outer areas in the first step,

the photoresist pattern is formed so that the inclination angle of the first inner-side defining face becomes smaller than the inclination angle of the first outer-side defining face, and the inclination angle of the second inner-side defining face becomes smaller than the inclination angle of the second outer-side defining face in the third step, and

the first coil pattern is formed so that a first inner-side base angle as one of the two base angles positioned on the side close to the center position becomes smaller than a first outer-side base angle positioned on the side far from the center position in the section of the first coil pattern, and the second coil pattern is formed so that a second inner-side base angle as one of the two base angles positioned on the side close to the center position becomes smaller than a second outer-side base angle positioned on the side far from the center position in the section of the second coil pattern in the fourth step.

19. A method of manufacturing a thin film coil according to claims 14, wherein the first and second exposure control layers are formed on a seed layer as the underlayer in the first step,

the photoresist is formed so as to cover the seed layer, the first exposure control layer, and the second exposure control layer in the second step,

the photoresist pattern is formed so that the seed layer is exposed to each of the first and second openings and the width of each of the first and second openings gradually decreases toward the seed layer in the third step,

the first and second coil patterns are formed by growing a plating film by using the seed layer in the fourth step, and

the method further comprises a sixth step of removing parts in the seed layer, which are not covered with the first and second coil patterns by selectively etching the seed layer by using both of the first and second coil patterns as a mask.

20. A method of manufacturing a thin film coil including a first coil pattern and a second coil pattern which are provided on a predetermined underlayer and turn spirally in parallel with each other around a predetermined center position,

wherein a process of forming the first and second coil patterns comprises:

a first step of, on the underlayer on which a photoresist pattern having a first inner frame part and a first outer frame part disposed so as to face each other, thereby defining a first opening for forming the first coil pattern, and a second inner frame part and a second outer frame part disposed so as to face each other, thereby defining a second opening for forming the second coil pattern is to be formed, patterning an exposure control layer for controlling progress of an exposing process so as to be formed in both of a first inner area which is positioned on the side close to the center position and in which the first inner frame part is to be formed and a first outer area which is positioned on the side far from the center position and in which the first outer frame part is to be formed, or in both of a second inner area which is positioned on the side close to the center position and in which the second inner frame part is to be formed and a second outer area which is positioned on the side far from the center position and in which the second outer frame part is to be formed;

a second step of forming a photoresist so as to cover the underlayer and the exposure control layer;

a third step of forming the first and second openings by patterning the photoresist by selective exposure, thereby forming the photoresist pattern on the underlayer so that the photoresist pattern has the first inner frame part disposed in the first inner area, the first outer frame part disposed in the first outer area, the second inner frame part disposed in the second inner area, and the second outer frame part disposed in the second outer area, width of each of the first opening and the second opening gradually decreases toward the underlayer, an inclination angle of a first inner-side defining face defining the first opening in the first inner frame part and an inclination angle of a first outer-side defining face defining the first opening in the first outer frame part are equal to each other, and an inclination angle of a second inner-side defining face defining the second opening in the second inner frame part and an inclination angle of a second outer-side defining face defining the second opening in the second outer frame part are equal to each other;

a fourth step of forming the first and second coil patterns in the first and second openings, respectively, in the photoresist pattern so that each of a section of the first coil pattern and a section of the second coil pattern has a trapezoid shape including one side which is positioned on the side far from the underlayer and specifies two base angles as a longer one of a set of opposite sides which are parallel to each other and the other side positioned on the side close to the underlayer as a shorter one of the set of opposite sides, and a shape of the section of the first coil pattern and a shape of the section of the second coil pattern are different from each other; and

a fifth step of removing the photoresist pattern and the exposure control layers used.

21. A method of manufacturing a thin film coil according to claim 20, wherein a reflection suppression layer for suppressing a reflection phenomenon at the time of exposure is formed as the exposure control layer in the first step.

22. A method of manufacturing a thin film coil according to claim 21, wherein the reflection suppression layer is formed in both of the first inner area and the first outer area in the first step,

the photoresist pattern is formed so that both of the inclination angle of the first inner-side defining face and the inclination angle of the first outer-side defining face become larger than both of the inclination angle of the second inner-side defining face and the inclination angle of the second outer-side defining face in the third step, and

the first and second coil patterns are formed so that both of a first inner-side base angle positioned on the side close to the center position as one of the two base angles and a first outer-side base angle positioned on the side far from the center position in the section of the first coil pattern become larger than both of a second inner-side base angle as one of the two base angles positioned on the side close to the center position and a second outer-side base angle positioned on the side far from the center position in the section of the second coil pattern in the fourth step.

23. A method of manufacturing a thin film coil according to claim 20, wherein a reflection promotion layer for promoting a reflection phenomenon at the time of exposure is formed as the exposure control layer in the first step.

24. A method of manufacturing a thin film coil according to claim 23, wherein the reflection promotion layer is formed in both of the second inner area and the second outer area in the first step,

the photoresist pattern is formed so that both of the inclination angle of the second inner-side defining face and the inclination angle of the second outer-side defining face become smaller than both of the inclination angle of the first inner-side defining face and the inclination angle of the first outer-side defining face in the third step, and

the first and second coil patterns are formed so that both of a second inner-side base angle as one of the two base angles positioned on the side close to the center position and a second outer-side base angle positioned on the side far from the center position in the section of the second coil pattern become smaller than both of a first inner-side base angle positioned on the side close to the center position as one of the two base angles in the section of the first coil pattern and a first outer-side base angle positioned on the side far from the center position in the fourth step.

25. A method of manufacturing a thin film coil according to any one of claims 20, wherein the exposure control layer is formed on a seed layer as the underlayer in the first step,

the photoresist is formed so as to cover the seed layer and the exposure control layer in the second step,

the photoresist pattern is formed so that the seed layer is exposed to each of the first and second openings and the width of each of the first and second openings gradually decreases toward the seed layer in the third step,

the first and second coil patterns are formed by growing a plating film by using the seed layer in the fourth step, and

the method further comprises a sixth step of removing parts in the seed layer, which are not covered with the first and second coil patterns by selectively etching the seed layer by using both of the first and second coil patterns as a mask.

26. A method of manufacturing a coil structure in which a thin film coil is buried between two magnetic substrates via an insulating layer, the thin film coil including a fist coil pattern and a second coil pattern which are provided on a predetermined underlayer and turn spirally in parallel with each other around a predetermined center position, comprising a step of forming the thin film coil so as to be buried between the two magnetic substrates via the insulating layer,

wherein a process of forming the first and second coil patterns comprises:

a first step of forming a photoresist on the underlayer;

a second step of forming a photoresist pattern by selectively exposing and patterning the photoresist while controlling progress in an exposing process so that the photoresist pattern has a first opening for forming the first coil pattern and a second opening for forming the second coil pattern and each of width of the first opening and width of the second opening gradually decreases toward the underlayer;

a third step of forming the first and second coil patterns in the first and second openings, respectively, in the photoresist pattern so that each of a section of the first coil pattern and a section of the second coil pattern has a trapezoid shape including one side which is positioned on the side far from the underlayer and specifies two base angles as a longer one of a set of opposite sides which are parallel to each other and the other side positioned on the side close to the underlayer as a shorter one of the set of opposite sides; and

a fourth step of removing the used photoresist pattern.