Power distribution for high-speed integrated circuits

• US 7,919,804 B2
• Filed: 12/01/2006
• Issued: 04/05/2011
• Est. Priority Date: 11/08/2005
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Oracle America, Inc. (Oracle Corporation)
• Inventors: Sauter, Karl, Horn, Kevin, Buhler, Otto Richard, Dillinger, Forest
• Primary Examiner(s): Pizarro; Marcos D.
• Assistant Examiner(s): MONTALVO, EVA Y
• Application Number:
  US11/565,818
• Publication Number:
  US 20070102806A1
• Time in Patent Office: 1,586 Days
• Field of Search: 257/301, 257/700, 257/698, 257/310, 257/501, 257/528, 174/260
• US Class Current: 257/310
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 23/49822 Multilayer substrates multilayer metallisation on monolayer substrate H01L23/498
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01068 Erbium [Er]
• CPC Class Codes: H05K 1/0231 Capacitors or dielectric substances
• CPC Class Codes: H05K 1/024 Dielectric details, e.g. changing the dielectric material around a transmission line
• CPC Class Codes: H05K 2201/0187 with regions of different dielectrics in the same layer, e.g. in a printed capacitor for locally changing the dielectric properties
• CPC Class Codes: H05K 2201/09309 Core having two or more power planes; Capacitive laminate of two power planes
• CPC Class Codes: H05K 2201/10734 Ball grid array [BGA]; Bump grid array

Abstract

An improved technique for power distribution for use by high speed integrated circuit devices. A mixture of high dielectric constant, Er and low Er materials are used in a dielectric layer sandwiched between the voltage and ground planes of a printed circuit board that is used to fixture one or more integrated circuit devices. The low Er material is used in an area contained by the location of the integrated circuit device and its corresponding decoupling capacitors located nearby. High Er material is used in areas between the regions of low Er material. The low Er material improves that speed at which current from an adjoining decoupling capacitor can propagate to a power pin of the integrated circuit device. The high Er material mitigates cross-coupling of noise between the low Er regions.

Claims

1. An electronic assembly, comprising:

a circuit board;

an integrated circuit attached to a top side of the printed circuit board;

a plurality of decoupling capacitors connected to the top side of the printed circuit board around a perimeter of the integrated circuit, the plurality of decoupling capacitors providing charge current to the integrated circuit;

a via fence surround the plurality of decoupling capacitors;

a first ground layer disposed below a bottom side of the circuit board;

a power layer disposed below the first ground layer;

a second ground layer disposed between the first ground layer and the power layer, the second ground layer extends widthwise between the via fence;

the circuit board including an inner dielectric layer comprising (i) a first material having a dielectric constant of approximately 12.5, and (ii) a second material having a dielectric constant of approximately 3;

the second material extending heightwise between a bottom side of the second ground layer and a top side of the power layer and widthwise between the via fence; and

the first material surrounding the second material, the first material forming at least a volume extending heightwise between the first ground layer and the second ground layer and widthwise between the via fence.

2. The electronic assembly of claim 1 wherein at least a portion of the first material is coplanar and laterally adjacent to the second material.

3. The electronic assembly of claim 1 wherein the via fence electrical interconnect of the first and second ground layers at the same electric potential.

4. An electronic assembly comprising:

a first ground layer comprising an electrically conductive material;

a second ground layer comprising the electrically conductive material;

a power layer comprising the electrically conductive material;

a first integrated circuit mounted on a top surface above the first ground layer having at least one pin electrically connected to the power layer and at least one pin electrically connected to the second ground layer, the at least one pin electrically connected to the second ground layer defining a first power node;

at least a first decoupling capacitor mounted on the top surface with the first integrated circuit, the at least the first decoupling capacitor having at least one pin connected to the power layer and at least one pin electrically connected to the second ground layer, the at least one pin connected to the power layer defining a second power node and providing charge current to the first integrated circuit;

a dielectric layer having at least two separate regions, with a first region consisting of a higher dielectric material than a second region consisting of a lower dielectric material, a dielectric differential between the higher and lower dielectrics being greater than 1;

wherein the second region is approximately equal to a length of the second ground layer and disposed between the second ground layer and the power layer such that the lower dielectric material is disposed between the first and second power nodes; and

wherein the first region consisting of the higher dielectric material is disposed between the second ground layer and the first ground layer and around the second region and the second ground layer.

5. The system of claim 4 wherein the higher dielectric material is one of barium titanate, tantalum oxide, aluminum oxide, alumina, borosilicate and mica.

6. The system of claim 4 wherein the lower dielectric material is a polymer film.

7. The system of claim 4 wherein the length of the second ground layer and the lower dielectric material is approximately equal to a length extending widthwise across a footprint of the integrated circuit and each of the at least one decoupling capacitors.

8. The of claim 4 further comprising:

a third ground layer comprising the electrically conducting material being independent from and coplanar and laterally adjacent with the second ground layer;

a via fence forming separate connections between the first ground layer and each of the second and third ground layers such that the each of the first, second, and third ground layers are electrically but not physically interconnected to share the same electrical potential;

a second integrated circuit mounted on a top surface above the first ground layer having at least one pin electrically connected to the power layer and at least one pin electrically connected to the third ground layer to define a third power node;

at least one second decoupling capacitor mounted on the top surface with the second integrated circuit, the at least one second decoupling capacitor having at least one pin connected to the power layer and at least one pin electrically connected to the third ground layer, the at least one second decoupling capacitor defining a fourth power node and providing charge current to the second integrated circuit;

wherein the dielectric layer includes a third region consisting of lower dielectric material that is independent from and coplanar and laterally adjacent with the second region;

wherein the third region consisting of the low dielectric region is approximately equal to a length of the third ground layer and disposed between the third ground layer and the power layer such that lower dielectric material is disposed between the third and fourth power nodes;

wherein the first region consisting of the high dielectric region is disposed between the third ground layer and the first ground layer and around opposed sides of both of the third region and the third ground layer; and

a second plurality of signal traces offset between the first and third conducting layers to define signal paths, the higher dielectric material of the first region covering the second plurality of signal paths.

9. An electronic assembly comprising:

an integrated circuit (IC) device connected to a ground plane and a power plane, the IC device characterized as having an outer peripheral that defines an IC footprint, the IC footprint defining a first area approximately equal to a length of the IC device times a width of the IC device;

a plurality of decoupling capacitors laterally adjacent to the IC device, the plurality of decoupling capacitors connected between the ground plane and the power plane to supply charge current to the IC device, the plurality of decoupling capacitors being disposed around the IC device to define a second area approximately equal to the first area plus additional area around the first area sufficient to encompass the IC footprint and the decoupling capacitors;

wherein the ground plane is comprised of planar first and second conducting layers, the first conducting layer being parallel to the second conducting layer, the first conducting layer being offset a first distance above the second conducting layer, the first conducting layer having a third area that aligns with and is larger than the second area, the second conducting layer having a fourth area that aligns with and is approximately equal to the second area;

wherein the power plane is comprised of a planar third conducting layer, the third conducting layer being parallel to the first and second conducting layers and offset a third distance below the second conducting layer, the third conducting layer having a fifth area that aligns with and is at least as large as the first conducting layer;

a low Er dielectric layer laminated to each of a top side of the third conducting layer and a bottom side of the second conducting layer, the low Er dielectric layer filling a first volume between the second conducting layer and the third conducting layer with low Er material, wherein a side of the first volume of the low Er material is defined as extending from the second conducting to the third conducting layer;

a high Er dielectric layer laminated to each of the top side of the third conducting layer, a top side of the second conducting layer, a bottom side of the first conducting material, and the side of the first volume of the low Er material, the high Er dielectric layer filling an second volume between the first conducting layer and the third conducting layer with high Er material;

the low dielectric layer having a dielectric constant of at least 1;

the high dielectric layer having a dielectric constant greater than one times the dielectric constant of the low dielectric layer.

10. The assembly of claim 9 further comprising a via fence for electrical interconnect of the second and first conducting layers such that the second and first conductive layers have the same electric potential.

11. The assembly of claim 9 wherein the dielectric constant of the low Er material is approximately k=3 and the high Er material is approximately k=12.5.

12. The assembly of claim 9 wherein the dielectric constant of the low Er material is approximate k<

3 and the high Er material is approximately k>

3.

13. The assembly of claim 9 wherein the low Er material has a value of 1<

k<

3 and the high Er material has a value of 3<

k<

7.

14. The assembly of claim 9 further comprising signal traces offset between the first and second conducting layers to define signal paths through the high Er dielectric layer and not the low Er dielectric layer.