Collective and synergistic MRAM shields

• US 20080122047A1
• Filed: 10/10/2007
• Published: 05/29/2008
• Est. Priority Date: 10/13/2006
• Status: Active Grant

• Current Assignee: Tessera, Inc. (Adeia Inc.)
• Original Assignee: Tessera, Inc. (Adeia Inc.)
• Inventors: Carlson, William Walter, Honer, Kenneth Allen, Gao, Guilian, Warner, Michael
• Granted Patent: US 8,269,319 B2
• Time in Patent Office: Days
• US Class Current: 257/660
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/4824 Connecting between the body and an opposite side of the item with respect to the body
• CPC Class Codes: H01L 2225/1023 the support being an insulating substrate
• CPC Class Codes: H01L 2225/1058 Bump or bump-like electrical connections, e.g. balls, pillars, posts
• CPC Class Codes: H01L 2225/107 Indirect electrical connections, e.g. via an interposer, a flexible substrate, using TAB printed circuits H05K1/00
• CPC Class Codes: H01L 23/552 Protection against radiation, e.g. light or electromagnetic waves
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 25/105 the devices being of a type provided for in group H01L27/00
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/15311 being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/15331 being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/207 Diameter ranges
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices

Abstract

Various structures chip packages are disclosed including a magnetoresistive random access memory (“MRAM”) device and a magnetic shield structure. The magnetic shield structure may be made from material having either ferromagnetic or diamagnetic material and may be shaped and incorporated into the chip package to divert stray magnetic fields away from the MRAM device.

Claims

1. A microelectronic component, comprising:

a die having top and bottom surfaces and edges extending between the top and bottom surfaces defining an outer periphery, the die including MRAM circuitry;

a first magnetic shield overlying the top surface; and

a second magnetic shield overlying the bottom surface.

2. The microelectronic component as claimed in claim 1 wherein the first and second magnetic shields extend beyond the outer periphery of the die.

3. The microelectronic component as claimed in claim 1, wherein at least one of the first and second magnetic shields has edges disposed beyond each of the edges of the die.

4. The microelectronic component as claimed in claim 1, wherein the first magnetic shield has a top surface facing away from the die, the microelectronic component further comprising a second die including MRAM circuitry overlying the top surface of the first magnetic shield, the second die having top and bottom surfaces and edges extending between the top and bottom surfaces defining an outer periphery, and a third magnetic shield overlying the second die and the top surface of the first magnetic shield, wherein the third magnetic shield extends beyond the outer periphery of the second die.

5. The microelectronic component as claimed in claim 1, wherein the first and second magnetic shields extend beyond an outer periphery of the MRAM circuitry.

6. The microelectronic component as claimed in claim 1, wherein the MRAM circuitry has edges defining the outer periphery of the MRAM circuitry and at least one of the first and second magnetic shields has edges disposed beyond each of the edges of the MRAM circuitry.

7. The microelectronic component as claimed in claim 1, wherein at least one of the first and second magnetic shields includes a ferromagnetic material.

8. The microelectronic component as claimed in claim 7, wherein the ferromagnetic material includes at least one metal selected from the group consisting of iron, nickel and cobalt.

9. The microelectronic component as claimed in claim 7, wherein the ferromagnetic material has a magnetic reluctance that is less than a magnetic reluctance of the die.

10. The microelectronic component as claimed in claim 1, wherein at least one of the first and second magnetic shields includes a diamagnetic material.

11. The microelectronic component as claimed in claim 10, the diamagnetic material selected from the group consisting of bismuth and pyrolitic graphite.

12. The microelectronic component as claimed in claim 1, wherein at least one of the first and second magnetic shields includes a polymeric material applied to a portion of the microelectronic component, the polymeric material containing a plurality of ferromagnetic particles interspersed therein.

13. The microelectronic component as claimed in claim 1, wherein the first magnetic shield defines a first major wall of a magnetic shielding enclosure, the second magnetic shield defines a second major wall of the magnetic shielding enclosure, the magnetic shielding enclosure further comprising a plurality of minor walls extending between the first and second major walls so as to define an aperture, wherein the die is disposed within the aperture.

14. The microelectronic component as claimed in claim 1 further including a substrate having a first face mounted to the top surface of the die, wherein the first magnetic shield overlies the substrate.

15. The microelectronic component as claimed in claim 1, wherein at least one of the first and second magnetic shields is mounted to the die.

16. The microelectronic component as claimed in claim 1, wherein at least one of the edges is canted at a non-right angle away from the bottom surface, wherein the second magnetic shield extends along the bottom surface and onto the at least one edge.

17. A microelectronic assembly, comprising:

a plurality of microelectronic subassemblies, each including;

a die having a first face, a second face remote from the first face and MRAM circuitry embedded therein;

a magnetic shield including a ferromagnetic material mounted to the first face of the die adapted to divert a stray magnetic field away from the MRAM circuitry; and

a plurality of support elements supporting the plurality of microelectronic subassemblies in stacked relation to each other so that the dies overlie one another.

18. The microelectronic assembly as claimed in claim 17, further comprising a second magnetic shield mounted to one of the dies at an open end of the stacked microelectronic subassemblies.

19. A microelectronic assembly, comprising:

a substrate having a first face and a second face remote from the first face;

a first die including MRAM circuitry mounted to the first face of the substrate;

a second die including MRAM circuitry mounted the second face of the substrate; and

a first and second magnetic shield, each having a major wall and a plurality of minor walls extending from the major wall to define a recess, the first die being disposed within the recess of the first magnetic shield and the second die being disposed within the recess of the second magnetic shield.

20. The microelectronic assembly as claimed in claim 19, wherein at least one of the first and second magnetic shields is mounted to at least one of the first and second faces of the substrate by an adhesive.

21. An MRAM device comprising:

an array of magnetic memory cells having a plurality of rows and a plurality of columns, each one of the plurality of rows and columns having a plurality of cells arranged therein;

a plurality of electrically conductive traces, each one of the plurality of traces corresponding to a respective one of the rows or one of the columns of the array of magnetic memory cells; and

a magnetic shielding layer coating an exposed surface of each of the plurality of conductive traces.

22. The MRAM device as claimed in claim 21 wherein each of the plurality of traces further includes a first surface facing the array of magnetic memory cells and a second surface remote from the first surface, the magnetic shielding layer coating the second surface of each of the plurality of conductive traces.

23. The MRAM device as claimed in claim 21 wherein the magnetic shielding layer includes a ferromagnetic material.

24. The MRAM device as claimed in claim 23 wherein the ferromagnetic material includes at least one metal selected from the group consisting of iron, nickel and cobalt.

25. A microelectronic assembly comprising:

a substrate extending in first and second transverse directions defining a plane;

at least one MRAM die conductively connected to the substrate;

a first electromagnetic coil oriented in the first direction;

a second electromagnetic coil oriented in the second direction;

a magnetic field sensor; and

control circuitry in electronic communication with the magnetic field sensor, the first electromagnetic coil and the second electromagnetic coil, the control circuitry being operable in response to output representing a magnetic field sensed by the magnetic field sensor to control the first and second electromagnetic coils to generate an opposite magnetic field for neutralizing the sensed magnetic field.