Monolithic inductor with magnetic flux lines guided away from substrate

• US 6,013,939 A
• Filed: 10/31/1997
• Issued: 01/11/2000
• Est. Priority Date: 10/31/1997
• Status: Expired due to Fees

• Current Assignee: National Science Counsel
• Original Assignee: National Science Counsel
• Inventors: Hashemi, Majid M., El-Sharawy, El-Badawy Amien
• Primary Examiner(s): LOKE, STEVEN HO YIN
• Application Number:
  US08/962,377
• Time in Patent Office: 802 Days
• Field of Search: 257/531, 324/127, 317/235 R, 336/200, 360/110, 437/60, 340/572
• US Class Current: 257/531
• CPC Class Codes: H01F 17/0006 Printed inductances printed coils for dynamo-electric machines H02K3/26; printed circuits H05K
• CPC Class Codes: H01L 23/5227 Inductive arrangements or effects of, or between, wiring layers other inductive arrangements H01L23/645
• CPC Class Codes: H01L 27/08 including only semiconductor components of a single kind
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A monolithic inductor (20, 20'"'"') is formed over a silicon or other substrate (22). The inductor (20, 20'"'"') includes at least one coil (62, 78) arranged so that its axis (58) is parallel to the substrate (22). Other inductive features, such as other coils (64, 70, 72) or planar spirals (74, 76) are arranged in series with the coil (62, 78) to guide magnetic flux lines away from the substrate (22). In one embodiment, a common thin film coil core (60) made from a magnetic material is provided for two coils (62, 64). The coil core (60) provides a continuous magnetic material flux path through the two coils (62, 64). In another embodiment, an axis (58) of the coil (78) is located between the plane in which two spirals (74, 76) are located and the substrate (22) to guide magnetic flux lines (82) away from the substrate (22).

Claims

1. A monolithic semiconductor inductive component comprising:

a semiconductor substrate which extends substantially in a plane;

a first coil having a first axis and being formed on said substrate so that said first axis is substantially parallel to said plane;

a second coil having a second axis and being formed on said substrate so that said second axis is substantially parallel to said plane, said second coil being electricaly connected in series with said first coil so that electrical current advances in substantially opposing directions along said first and second axes through said first and second coils, respectively; and

a coil core formed on said substrate and formed from a magnetic material and configured so that a substantially continuous path of magnetic material passes through said first and second coils along said first and second axes;

wherein

said first coil, said second coil, and said coil core form a monolithic inductor having magnetic flux lines guided away front said substrate.

2. An inductive component as claimed in claim 1 wherein said first and second axes are substantially straight and said first and second axes are substantially parallel to one another.

3. An inductive component as claimed in claim 2 additionally comprising a third coil having a third axis and being formed on said substrate so that said third axis is substantially parallel to said plane and substantially perpendicular to said first and second axes, said third coil being electrically connected in series between said first and second coils.

4. An inductive component as claimed in claim 3 additionally comprising a fourth coil having a fourth axis and being formed on said substrate so that said fourth axis is substantially parallel to said plane and substantially parallel to said third axis, said fourth coil being electrically connected in series with one of said first and second coils so that electrical current advances in substantially opposing directions along said third and fourth axes through said third and fourth coils, respectively.

5. An inductive component as claimed in claim 1 wherein:

said first coil overlies a first area on said substrate;

said second coil overlies a second area on said substrate; and

said coil core overlies the entirety of said first and second areas.

6. An inductive component as claimed in claim 5 wherein:

said first and second coils are spaced apart from one another by an inter-coil gap area; and

said coil core overlies an area of said substrate which is greater than said first and second areas plus said inter-coil gap area.

7. An inductive component as claimed in claim 5 wherein:

said first coil includes a plurality of spaced apart traces, said traces extending for a width distance in a direction substantially parallel to said plane and perpendicular to said first axis; and

said coil core overlies an area of said substrate which extends at least substantially said width distance beyond said traces along said first axis.

8. An inductive component as claimed in claim 1 wherein:

said first coil includes first and second end traces spaced apart from one another along said first axis;

said second coil includes third and fourth end traces spaced apart from one another along said second axis;

said first and second axes are substantially parallel to one another; and

said first and third end traces are positioned proximate a first line passing substantially perpendicularly through said first and second axes.

9. An inductive component as claimed in claim 8 wherein:

said second and fourth end traces are positioned proximate a second line passing perpendicularly through said first and second axes.

10. An inductive component as claimed in claim 1 wherein said substrate is formed substantially of silicon.

11. An inductive component as claimed in claim 1 wherein:

a first insulative layer overlies said substrate;

a first electrically conductive layer overlies said first insulative layer, said first electrically conductive layer being formed into first spaced apart traces;

a second insulative layer overlies said first conductive layer;

a magnetic material layer overlies said second insulative layer;

a third insulative layer overlies said magnetic material layer;

a second electrically conductive layer overlies said third insulative layer, said second electrically conductive layer being formed into second spaced apart traces;

a plurality of electrically conductive plugs extending from said first traces to said second traces through said second and third insulative layers; and

said first traces, said second traces and said conductive plugs are configured to form said first coil and to form said second coil; and

said magnetic material layer forms said coil core.

12. An inductive component as claimed in claim 11 wherein said magnetic material layer is less than 15 microns thick.

13. An inductive component as claimed in claim 11 wherein:

said magnetic material layer is dimensioned to overlie a substantially continuous area over said first traces; and

said conductive plugs extend through and contact said magnetic material layer.

14. A monolithic semiconductor inductive component comprising:

a semiconductor substrate which extends substantially in a plane;

a first conductive spiral having a first axis and being formed on said substrate so that said first axis is substantially perpendicular to said plane;

a second conductive spiral having a second axis and being formed on said substrate so that said second axis is substantially perpendicular to said plane and substantially parallel to said first axis; and

a conductive coil having a third axis and being formed on said substrate so that said third axis is substantially parallel to said plane, said coil being electrically coupled in series with said first and second spirals, and said coil being physically located between said first and second spirals;

wherein

said first conductive spiral, said second conductive spiral, and said conductive coil form a monolithic inductor having magnetic flux lines guided away from said substrate.

15. An inductive component as claimed in claim 14 wherein said first and second axes reside proximate a line extending along said third axis.

16. An inductive component as claimed in claim 14 wherein:

said first spiral is spaced apart from said plane of said substrate;

said second spiral is spaced apart from said plane of said substrate;

said third axis is positioned between said plane of said substrate and said first spiral; and

said third axis is positioned between said plane of said substrate and said second spiral.

17. An inductive component as claimed in claim 14 wherein:

magnetic flux lines for said first spiral point in a first direction along said first axis;

magnetic flux lines for said second spiral point in a second direction along said second axis; and

said first direction opposes said second direction.

18. An inductive component as claimed in claim 14 wherein said substrate is formed substantially of silicon.

19. An inductive component as claimed in claim 14 wherein:

a first insulative layer overlies said substrate;

a first electrically conductive layer overlies said first insulative layer, said first electrically conductive layer being formed into first spaced apart traces;

a second insulative layer overlies said first conductive layer;

a second electrically conductive layer overlies said second insulative layer, said second electrically conductive layer being formed into said first spiral, said second spiral, and second spaced apart traces;

a plurality of electrically conductive plugs extending from said first traces to said second traces through said second insulative layer; and

said first traces, said second traces and said conductive plugs are configured to form said coil.

20. A monolithic semiconductor inductive component comprising:

a semiconductor substrate which extends substantially in a plane;

a first coil formed on said substrate to overlie a first area of said substrate, said first coil having a first axis extending substantially parallel to said plane;

a second coil formed on said substrate to overlie a second area of said substrate, said second coil having a second axis extending substantially parallel to said plane and to said first axis, said second coil being spaced apart from said first coil by an inter-coil gap area, and said second coil being electrically connected in series with said first coil so that electrical current advances in substantially opposing directions along said first and second axes through said first and second coils, respectively; and

a coil core formed on said substrate and formed of a magnetic material and configured to overlie an area of said substrate that extends beyond said first area, said second area and said inter-coil gap area so that a substantially continuous path of magnetic material passes through said first and second coils along said first and second axes;

wherein

said first coil, said second coil, and said coil core form a monolithic inductor having magnetic flux Lines guided away from said substrate.

21. A monolithic semiconductor inductive component comprising:

a semiconductor substrate having a planar surface;

a conductive coil having a coil axis and being formed on said substrate so that said coil axis extends along a line substantially parallel to said planar surface of said substrate;

a first conductive spiral formed on said substrate and spaced apart from said planar surface, said first spiral having a first axis line that is substantially perpendicular to said planar surface and proximate said line along which said coil axis extends; and

a second conductive spiral formed on said substrate and spaced apart from said planar surface, said second spiral having a second axis line that is substantially perpendicular to said planar surface and proximate said line along which said coil axis extends;

wherein said conductive coil, said first conductive spiral, and said second conductive spiral form a monolithic inductor having magnetic flux lines guided away from said substrate, said coil is located between said first and second conductive spirals, said coil is electrically coupled in series with said first and second spirals so that magnetic flux lines for said first spiral and for said second spiral point in substantially opposing directions, and said coil axis is positioned between said planar surface of said substrate and said first spiral and between said planar surface of said substrate and said second spiral.