Electrically decoupled integrated transformer having at least one grounded electric shield

• US 7,733,205 B2
• Filed: 05/10/2006
• Issued: 06/08/2010
• Est. Priority Date: 12/15/2003
• Status: Active Grant

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Corporation
• Inventors: Hyvönen, Lassi Pentti Olavi
• Primary Examiner(s): NGUYEN, TUYEN T
• Application Number:
  US11/432,109
• Publication Number:
  US 20060202789A1
• Time in Patent Office: 1,490 Days
• Field of Search: 336/65, 336/84.R, 336/84.C, 336/200, 336206-208, 336/232, 336/23, 257/531
• US Class Current: 336/84.00C
• CPC Class Codes: H01F 17/0013 with stacked layers
• CPC Class Codes: H01F 2027/348 Preventing eddy currents
• CPC Class Codes: H01F 27/36 Electric or magnetic shields or screens movable for varying inductance H01F21/10
• CPC Class Codes: H01F 27/363 made of electrically conductive material
• CPC Class Codes: H01L 23/5225 Shielding layers formed together with wiring layers
• CPC Class Codes: H01L 23/5227 Inductive arrangements or effects of, or between, wiring layers other inductive arrangements H01L23/645
• 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
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

An integrated circuit, such as a radio frequency integrated circuit (RFIC), has a first layer bearing first metallization patterned for defining a first inductive coil, a second layer bearing second metallization patterned for defining a second inductive coil that overlies the first inductive coil and that is magnetically coupled to the first inductive coil through a third layer interposed between the first layer and the second layer. The third layer bears third metallization for defining an electric shield or electrostatic shield. The third metallization is patterned into a plurality of structures having shapes intended to minimize eddy currents. The electric shield is connected to further metallization that carries a ground potential. The third layer may further bear other metallization for coupling together at least two components of the integrated circuit. The integrated circuit may be fabricated by a CMOS process, and the first and second coils may be a primary coil and a secondary coil, respectively, of a radio frequency transformer. An additional electric shield may also be included, and in this case one electric shield can be coupled to a ground potential associated with the primary coil, and the second electric shield can be coupled to a ground potential associated with the secondary coil.

Claims

1. An apparatus comprising:

a first dielectric layer in an integrated circuit comprising a first inductance;

a second dielectric layer in the integrated circuit comprising a second inductance that is spaced from the first inductance and that overlies the first inductance;

an electrically conductive shield in the integrated circuit, disposed between the first and second inductances and spaced from each of the first and second inductances, for coupling a capacitance between the first and second inductance to ground, in which the electrically conductive shield comprises a plurality of radially extending conductive shapes that are spaced from one another and electrically coupled to one another.

2. The apparatus of claim 1, wherein the electrically conductive shield is a first shield, the apparatus further comprising a second electrically conductive shield disposed between the first shield and the second inductance, spaced from each of the first shield and the second inductance, and coupled to ground.

3. The apparatus of claim 2, wherein the first shield and the first inductance are coupled to a common first grounding metallization of the integrated circuit, and the second shield and the second inductance are coupled to a common second grounding metallization of the integrated circuit.

4. The apparatus of claim 1, wherein the shield couples the capacitance to ground at a location outboard of the shield.

5. The apparatus of claim 1, wherein the shield couples the capacitance to ground at a location substantially aligned with a geometric center of one of the first or second inductances.

6. The apparatus of claim 1, wherein the shapes are electrically coupled to one another such that none of the said shapes forms a loop with any other said shape.

7. The apparatus of claim 6, wherein the radially extending conductive shapes are electrically coupled to one another by a broken ring.

8. The apparatus of claim 7, wherein the broken ring is disposed inboard of an outer periphery of the shield.

9. The apparatus of claim 6, wherein the shapes comprise ribbons.

10. The apparatus of claim 9, wherein each ribbon defines a width no greater than the distance between the shield and the nearer of the first or second inductor.

11. The apparatus of claim 9, wherein a distance between any two adjacent ribbons is no greater than half the distance between the shield and the nearer of the first or second inductor.

12. The apparatus of claim 9, wherein the ribbons define a common width, and a spacing between any two adjacent ribbons is about half the common width.

13. The apparatus of claim 9, wherein the radially extending ribbons are formed in groups of ribbons, each ribbon of a group coupled to other ribbons of the group, and each group coupled to each other group at a common connection to ground.

14. The apparatus of claim 13, wherein said common connection to ground is disposed at about a physical center of the groups.

15. The apparatus of claim 1, wherein the shield is formed of an electrically conductive non-metal.

16. The apparatus of claim 1, wherein the shield couples a capacitance between the first and second inductances to ground through use of a conductive via that penetrates at least one of the first and second dielectric layers to contact grounding metallization of the integrated circuit.

28. The apparatus of claim 1, further comprising a third dielectric layer disposed between the first and second inductances.

29. The apparatus of claim 28, wherein the first and second inductances are magnetically coupled through the third dielectric layer.

17. An apparatus comprising:

a first inductive coil;

a second inductive coil overlying the first inductive coil;

a first electric shield disposed between the first and second inductive coils; and

a second electric shield disposed between and spaced from each of the first electric shield and the second inductive coil;

wherein each of the first and second electric shields comprises a plurality of radially extending electrically conductive ribbons coupled to one another in a manner such that no ribbon forms a loop with any other ribbon.

18. The apparatus of claim 17, wherein the first inductive coil and the first shield are grounded to a first grounding metallization, and the second conductive coil and the second shield are grounded to a second grounding metallization.

19. An integrated circuit comprising:

a planar first coil of conductive material disposed in a first dielectric layer;

a planar second coil of conductive material disposed in a second dielectric layer, the second coil of conductive material overlying the first coil of conductive material and magnetically coupled to the first coil of conductive material through a shield disposed between the first coil of conductive material and the second coil of conductive material;

the shield configured to couple a capacitance between the first coil of conductive material and the second coil of conductive material, and to provide an inductance to a ground potential, the shield comprising a planar conductive material patterned into a plurality of radially extending ribbons coupled to a common point that lies in a same plane as the ribbons, said point coupled to the ground potential.

20. An integrated circuit comprising:

a planar first coil of conductive material disposed in a first dielectric layer;

a planar second coil of conductive material disposed in a second dielectric layer, the second coil of conductive material overlying the first coil of conductive material and magnetically coupled to the first coil of conductive material through a shield disposed between the first coil of conductive material and the second coil of conductive material;

the shield configured to couple a capacitance between the first coil of conductive material and the second coil of conductive material, and to provide an inductance to a ground potential, the shield comprising a planar conductive material patterned into a plurality of radially extending ribbons, each of said ribbons coupled to each other of said ribbons such that no ribbon forms a loop with any other ribbon.

21. The integrated circuit of claim 20, wherein the first coil is formed of a conductive metal and the second coil is formed of a conductive metal.

22. The integrated circuit of claim 20, wherein each ribbon defines a width no greater than the distance between the shield and the nearer of the first or second coil.

23. The integrated circuit of claim 20, wherein a distance between any two adjacent ribbons is no greater than half the distance between the shield and the nearer of the first or second coil.

24. The integrated circuit of claim 20, wherein all ribbons define a common width, and a spacing between any two adjacent ribbons is about half the common width.

25. A transformer in an integrated circuit comprising:

a first inductor in or on a first integrated circuit layer;

a second integrated circuit layer overlying the first inductor;

an electric shield over the second integrated circuit layer and overlying the first inductor, said electric shield patterned into a plurality of radially extending electrically conductive ribbons, each ribbon coupled to a common point;

a third integrated circuit layer over the electric shield; and

a second inductor in or on the third integrated circuit layer and overlying the electric shield such that at least a portion of the third integrated circuit layer separates the second inductor from the electric shield;

wherein the common point is electrically coupled to grounding metallization of the integrated circuit; and

wherein at least one of;

each of the radially extending ribbons defines a width that is a function of a frequency of an electrical signal that is to be applied to the first or second inductors; and

adjacent ones of said ribbons are spaced from one another by a distance that is a function of a spacing between the first and second inductors.

27. The transformer of claim 25, wherein each of the second and third IC layers comprises a dielectric material.

26. A transformer in an integrated circuit comprising:

a first inductor in or on a first integrated circuit layer;

a second integrated circuit layer overlying the first inductor;

an electric shield over the second integrated circuit layer and overlying the first inductor, said electric shield patterned into a plurality of radially extending electrically conductive ribbons, each ribbon coupled to a common point;

a third integrated circuit layer over the electric shield; and

a second inductor in or on the third integrated circuit layer and overlying the electric shield such that at least a portion of the third integrated circuit layer separates the second inductor from the electric shield;

wherein the common point is electrically coupled to grounding metallization of the integrated circuit

wherein adjacent ones of said ribbons are spaced from one another by a distance that is on the order of twice a width of said adjacent ones of said ribbons.