Chip cooling

• US 6,774,482 B2
• Filed: 12/27/2002
• Issued: 08/10/2004
• Est. Priority Date: 12/27/2002
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Colgan, Evan George, Wisnieff, Robert Luke, Magerlein, John Harold, Zitz, Jeffrey Allen
• Primary Examiner(s): CLARK, JASMINE JHIHAN B
• Application Number:
  US10/330,742
• Publication Number:
  US 20040124525A1
• Time in Patent Office: 592 Days
• Field of Search: 257/712, 257/700, 257/707, 257/713, 257/720, 257/730
• US Class Current: 257/712
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 23/367 Cooling facilitated by shape of device H01L23/38, H01L23/40, H01L23/42, H01L23/44, H01L23/46 take precedence
• CPC Class Codes: H01L 23/42 Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
• 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 2924/00014 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 2924/10253 Silicon [Si]

Abstract

In an integrated circuit structure, such as in an MCM or in an SCM, a particulate thermally conductive conformable material, such as a thermal paste, is applied between a heat-generating chip and a cooling plate. Modification of the microstructure of at least one of the two nominally parallel surfaces which are in contact with the material is provided in a discrete pattern of sloped recesses. The largest particles in the material preferentially migrate downward into the recesses. The average thickness of the conductive paste is reduced to below the diameter of the largest particles dispersed in the material, providing improved cooling.

Claims

1. An integrated circuit chip structure, comprising one or more semiconductor chips having a first major chip surface substantially parallel to and facing a first major cooling plate surface, wherein the respective first major chip surface and first major cooling plate surface are separated from each other by a layer of thermally conductive conformable material therebetween, and wherein the first major chip surface is completely provided with a discretely shaped recessed microstructure.

2. An integrated circuit chip structure, comprising one or more semiconductor chips having a flat major chip surface substantially parallel to and facing a first major cooling plate surface, wherein the respective first major chip surface and firt major cooling plate surface are separated from each other by a layer of thermally conductive conformable material therebetween, and wherein the first major chip surface is completely provided with a discretely shaped recessed microstructure comprising a repeating unit of adjacent recessed cells, within which cells slope-walled surfaces connect a recessed bottom surface with a projecting flat surface and wherein the slope-walled surfaces have an average slope of about 5 degrees to about 80 degrees.

3. The structure recited in claim 2, wherein the layer of thermally conductive conformable material is selected from the group consisting of thermal paste, thermal grease, phase-change material, particle-filled silicone, dry particle lubricant, and dry deformable metal particles.

4. The structure recited in claim 2, wherein the repeating unit of adjacent recessed cells covers a two-dimensional surface in which the minimum width between projecting adjacent flat surfaces is less than about 0.5 millimeters.

5. The structure recited in claim 2, wherein the recessed bottom surface is provided with a microstructure having a height less than about 25% of recessed cell depth.

6. The structure recited in claim 2, wherein the slope-walled surfaces have an average slope of about 30 degrees to about 70 degrees.

7. The structure recited in claim 2, wherein about 60% to about 99% of the area of the discretely shaped microstructure comprises recessed surfaces and sloped surfaces.

8. The structure recited in claim 2, wherein the longer dimension of the slope-walled cell is oriented parallel to a nearest chip edge.

9. An integrated circuit chip structure, comprising one or more semiconductor chips having a first major chip surface substantially parallel to and facing a first major cooling plate surface, wherein the respective first major chip surface and the first major cooling plate surface are separated from each other by a layer of thermally conductive conformable material therebetween, and wherein the first major cooling plate surface is provided with a discretely shaped recessed microstructure.

10. An integrated circuit chip structure, comprising one or more semiconductor chips having a first major chip surface substantially parallel to and facing a first major cooling plate surface, wherein the respective first major chip surface and the first major cooling plate surface are separated from each other by a layer of thermally conductive conformable material therebetween, and wherein the first major cooling plate surface is provided with a discretely shaped recessed microstructure comprising a repeating unit of adjacent recessed cells, within which cells slope-walled surfaces connect a recessed bottom surface with a projecting flat surface and wherein the slope-walled surfaces have an average slope of about 5 degrees to about 80 degrees.

11. The structure recited in claim 10, wherein the slope-walled surfaces feature a profile selected from the group consisting of curved, faceted, straight and any combination thereof.

12. The structure recited in claim 10, wherein the layer of thermally conductive conformable material is selected from the group consisting of thermal paste, thermal grease, phase-change material, particle-filled silicone, dry particle lubricant, and dry deformable metal particles.

13. The structure recited in claim 10, wherein the repeating unit of adjacent recessed cells covers a two-dimensional surface in which the minimum width between projecting adjacent flat surfaces is less than about 0.5 millimeters.

14. The structure recited in claim 10, wherein the recessed bottom surface is provided with a microstructure having a height less than about 25% of recessed cell depth.

15. The structure recited in claim 10, wherein the slope-walled surfaces have an average slope of about 30 degrees to about 70 degrees.

16. The structure recited in claim 10, wherein about 60% to about 99% of the discretely shaped microstructure comprises recessed surfaces and sloped surfaces, in region facing a first major chip surface.

17. The structure recited in claim 10, wherein the longer dimension of the slope-walled cell is oriented parallel to a nearest chip edge.

18. An integrated circuit chip structure, comprising one or more semiconductor chips having a first major chip surface substantially parallel to a first major cooling plate surface, wherein the respective first major chip surface and first major cooling plate surface are separated from each other by a heat spreader having a first surface facing the first surface of the one or more chip and a second surface facing toward the first surface of the cooling plate, wherein there is also a layer of thermally conductive conformable material between the heat spreader and the cooling plate, and wherein a discretely shaped recessed microstructure is provided on at least one of the second major surface of the heat spreader and the first major surface of the cooling plate.

19. A method for reducing the thermal resistance along the primary heat dissipation path from one or more chips in an integrated circuit chip package, comprising:

a providing a cooling plate having a first major surface;

b. providing at least one semiconductor chip having a first major surface substantially parallel to the first major surface of the cooling plate;

c. providing at least one of the first major surfaces with a discretely shaped recessed microstructure;

d. providing between the first major surface having the discretely shaped recessed microstructure and the remaining first major surface a layer of conformable thermally conductive material containing particulate material in a range of sizes; and

e. applying pressure to the layer of conformable thermally conductive material, causing the largest particles of the particulate material to be preferentially distributed into the discretely shaped recessed microstructure, thereby reducing the average thickness and the effective thickness of the layer of thermally conductive material.

20. A method for reducing the thermal resistance along the primary heat dissipation path from one or more chips in an integrated circuit chip package, comprising:

a. providing a cooling plate having a first major surface;

b. providing at least one semiconductor chip having a first major surface substantially parallel to the first major surface of the cooling plate;

c. providing at least one of the first major surfaces with a pattern of discretely shaped recessed microstructure comprising a repeating unit of adjacent slope-walled recessed cells;

d. providing a layer of conformable thermally conductive material between the first major surface having the discretely shaped recessed microstructure and the remaining first major surface a layer of conformable thermally conductive material containing particulate material in a range of sizes; and

e. applying pressure to the layer of conformable thermally conductive material, causing the largest particles of the particulate material to be preferentially distributed into the discretely shaped recessed microstructure, thereby reducing the average thickness and the effective thickness of the layer of thermally conductive material.

21. The method recited in claim 20, wherein the step of providing at least one of the first major surfaces with a discretely shaped recessed microstructure comprises providing a first cooling plate surface with a discretely shaped recessed microstructure by a method selected from the group consisting of anisotropic wet etching, diamond ruling and electroforming.

22. The method recited in claim 20, wherein the step of providing at least one of the first major surfaces with a discretely shaped recessed microstructure comprises completely providing the at least one first major chip surface with a discretely shaped recessed microstructure by anisotropic wet etching.

23. The method recited in claim 20, wherein the step of providing a pattern comprising a repeating unit of adjacent slope-walled recessed cells comprises providing a pattern comprising a repeating unit of adjacent slope-walled recessed cells wherein about 60% to about 99% of each cell is comprised of recessed surfaces and sloped surfaces, in the region of the at least one of the first major surfaces which is in contact with a layer of conformable thermally conductive material, each of the cells having a minimum width of between about 5 microns and about 200 microns.

24. The method recited in claim 20, wherein the step of providing a discretely shaped recessed microstructure comprises providing a pattern comprising a repeating unit of adjacent recessed slope-walled cells, wherein the angle of slope is between about 30 degrees to about 80 degrees.

25. A method for reducing the thermal resistance along the primary heat dissipation path from one or more chips in an integrated circuit package, comprising:

a. providing a cooling plate having a first major surface;

b. providing at least one semiconductor chip having a first major surface substantially parallel to the first major surface of the cooling plate;

c. providing between the cooling plate and the at least one chip a heat spreader having a first surface facing the first major surface of the at least one chip and a second surface facing toward the first surface of the cooling plate;

d. providing a layer of thermally conductive conformable material between the heat spreader and the cooling plate; and

e. providing a discretely shaped recessed microstructure on at least one of the second major surface of the heat spreader and the first major surface of the cooling plate.

26. A method for reducing the migration of a conformable thermally conductive material in an integrated circuit chip package, comprising:

a. providing a cooling plate having a first major surface;

b. providing at least one semiconductor chip having a first major surface substantially parallel to the first major surface of the cooling plate;

c. providing at least one of the first major surfaces with a discretely shaped recessed microstructure;

d. providing between the first major surface having the discretely shaped recessed microstructure and the remaining first major surface a layer of conformable thermally conductive material containing particles in a range of sizes; and

e. applying pressure to the layer of conformable thermally conductive material, causing the largest particles in the range of sizes to be preferentially distributed into the discretely shaped recessed microstructure, thereby reducing the average thickness and the effective thickness of the layer of thermally conductive material.

27. A method for reducing the migration of a conformable thermally conductive material in an integrated circuit package, comprising:

a. providing a cooling plate having a first major surface;

b. providing at least one semiconductor chip having a first major surface substantially parallel to the first major surface of the cooling plate;

c. providing between the cooling plate and the at least one chip a heat spreader having a first surface facing the first major surface of the at least one chip and a second surface facing toward the first surface of the cooling plate;

d. providing a layer of thermally conductive conformable material between the heat spreader and the cooling plate; and

e. providing a discretely shaped recessed microstructure on at least one of the second major surface of the heat spreader and the first major surface of the cooling plate.