Multi-Layer, Multi-Material Fabrication Methods for Producing Micro-Scale and Millimeter-Scale Devices with Enhanced Electrical and/or Mechanical Properties

• US 20110132767A1
• Filed: 10/18/2010
• Published: 06/09/2011
• Est. Priority Date: 02/04/2003
• Status: Active Grant

• Current Assignee: University of Southern California
• Original Assignee: Microfabrica Incorporated (Technoprobe S.P.A.)
• Inventors: Cohen, Adam L., Kim, Kieun, Kim, Young, Larsen, Rulon Joseph III, Wu, Ming Ting, Smalley, Dennis R., Lockard, Michael S., Kumar, Ananda H.
• Granted Patent: US 8,613,846 B2
• Time in Patent Office: Days
• US Class Current: 205/118
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: C23C 18/1605 by masking
• CPC Class Codes: C23C 18/1651 Two or more layers only obtained by electroless plating
• CPC Class Codes: C25D 1/003 3D structures, e.g. superposed patterned layers
• CPC Class Codes: G01R 1/06716 Elastic
• CPC Class Codes: G01R 1/06744 Microprobes, i.e. having dimensions as IC details
• CPC Class Codes: G01R 1/06755 Material aspects
• CPC Class Codes: G01R 3/00 Apparatus or processes specially adapted for the manufacture or maintenance of measuring instruments , e.g. of probe tips
• CPC Class Codes: H01L 21/4853 Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps

Abstract

Some embodiments of the invention are directed to electrochemical fabrication methods for forming structures or devices (e.g. microprobes for use in die level testing of semiconductor devices) from a core material and a shell or coating material that partially coats the surface of the structure. Other embodiments are directed to electrochemical fabrication methods for producing structures or devices (e.g. microprobes) from a core material and a shell or coating material that completely coats the surface of each layer from which the probe is formed including interlayer regions. Additional embodiments of the invention are directed to electrochemical fabrication methods for forming structures or devices (e.g. microprobes) from a core material and a shell or coating material wherein the coating material is located around each layer of the structure without locating the coating material in inter-layer regions. Each of these groups of embodiments incorporate both the core material and the coating material during the formation of each layer and each layer is also formed with a sacrificial material that is removed after formation of all layers of the structure. In some embodiments the core material may be a genuine structural material while in others it may be only a functional structural material (i.e. a material that would be removed with sacrificial material if it were accessible by an etchant during removal of sacrificial material.

Claims

1. A fabrication process for forming a multi-layer three-dimensional structure, comprising:

(a) forming a first layer comprising at least one structural material and at least one sacrificial material;

(b) forming at least one additional layer from at least one structural material and at least one sacrificial material wherein the at least one additional layer is formed on and adhered to a previously formed layer, and wherein the first layer and the at least one additional layer together form a multi-layer three-dimensional structure; and

(c) after formation of a plurality of layers, separating at least a portion of the at least one sacrificial material forming a portion of the plurality of layers from the at least one structural material forming another portion of the plurality of layers, wherein a given one of the layers comprises at least one sacrificial material and at least two structural materials, wherein the at least two structural materials on the given layer comprise a core-structural material located at the upper boundary level of the given layer but not at the lower boundary level of the given layer and a shell structural material bounding the sides of the core material and located below the core material and above the lower boundary level of the given layer such at the shell structural material bounds the bottom of said core structural material on the given layer.

2. The process of claim 1 wherein the at least one structural material and the at least one sacrificial material forming a layer immediately preceding the given layer comprise conductive materials.

3. The process of claim 1 wherein the given layer has a layer thickness and wherein the shell structural material is deposited into a void within a pattern to a thickness that is less than a thickness of the given layer;

and wherein the core structural material is deposited to occupy a void remaining between deposited shell structural material and an upper boundary level for the given layer.

4. The process of claim 3 wherein the void has a conductive bottom and conductive side walls onto which the shell structural material is electrodeposited.

5. The process of claim 4 wherein the walls of the void are formed from sacrificial material.

6. The process of claim 1 wherein the shell structural material is deposited to have side walls having a width of that is controlled by a deposition thickness of the deposited shell structural material.

7. The process of claim 1 wherein the shell structural material is deposited to have sidewalls having a width and wherein the width of the side walls is not controlled by a width of the void into which the shell structural material is deposited.

8. The process of claim 1 wherein the formation of each of a plurality of layers comprises a planarization of the at least one sacrificial material and the at least one structural material forming a plurality of the layers.

9. The process of claim 1 wherein a layer immediately succeeding the given layer defines a capping layer comprising a capping structural material that provides a cap that in combination with the shell structural material of the given layer completes encapsulation of the core material of the given layer and wherein the capping layer additionally comprises a sacrificial material that occupies at least portions of the layer not occupied by the capping structural material, and wherein the capping structural material and sacrificial material on the succeeding layer are planarized to set a boundary level of the succeeding layer.

10. The process of claim 1 wherein a capping structural material deposition, comprising a material different from the core structural material, is made immediately above the given layer to provide a cap that in combination with the shell structural material of the given layer completes encapsulation the core material of the given layer.

12. The process of claim 1 wherein the given layer comprises a plurality of given layers with each comprising a core structural material, a shell structural material, and a sacrificial material.

13. The process of claim 1 wherein the given layer is succeeded by a succeeding layer that has a configuration relative to the given layer that ensures that a location of the at least one structural material on the succeeding layer completes encapsulation of the core material on the given layer.

14. The process of claim 1 wherein the shell structural material has a wall thickness that is less than a minimum features size for the process as implemented in forming the given layer.

49. The process of claim 1 wherein formation of the given layer comprises:

(i) applying a photoresist to a surface of a layer immediately preceding the given layer;

(ii) patterning and developing the photoresist to forming at least one opening in the photoresist where the sacrificial material is to be deposited;

(iii) depositing the sacrificial material to form a portion of the given layer;

(iv) removing the photoresist to leave a void in the sacrificial material into which structural material is to be deposited;

(v) depositing a shell structural material to a depth less than a desired thickness of the given layer such that a base and sidewalls of the shell structural material are deposited;

(vi) depositing a core structural material to a depth that raises a net thickness of deposited structural material to a height that is at least as great as the desired thickness of the given layer;

(vii) planarizing the sacrificial material, the shell structural material and the core structural material to a height that sets a boundary level for the given layer.

50. The process of claim 1 wherein the structure comprises a plurality of substantially identical structures that are being formed in a batch process simultaneously and wherein at least a portion of the depositing steps comprise electroplating steps.

51. The process of claim 50 wherein the structure comprises design features having micron scale dimensions.

11. (canceled)

15. A fabrication process for forming a multi-layer three-dimensional structure, comprising:

(a) forming a first layer comprising at least one structural material and at least one sacrificial material;

(b) forming at least one additional layer from at least one structural material and at least one sacrificial material wherein the at least one additional layer is formed on and adhered to a previously formed layer, and wherein the first layer and the at least one additional layer together form a multi-layer three-dimensional structure; and

(c) after formation of a plurality of layers, separating at least a portion of the at least one sacrificial material forming a portion of the plurality of layers from the at least one structural material forming another portion of the plurality of layers, wherein a given one of the layers comprises at least one sacrificial material and at least two structural materials, wherein the at least two structural materials comprise a core structural material located at the lower boundary level of the given layer but not at the upper-boundary level of the given layer and a shell structural material bounding the sides of the core material and providing a cap located above the core structural material and below the upper boundary of the given layer such that the shell material bounds the top of the core structural material one the given layer.

18. The process of claim 15 wherein a layer immediately preceding the given layer defines a capping layer comprising a capping structural material that provides a base that in combination with the shell structural material of the given layer completes encapsulation of the core material of the given layer and wherein the capping layer additionally comprises a sacrificial material that occupies at least portions of the layer not occupied by the capping structural material, and wherein the capping structural material and sacrificial material on the preceding layer are planarized to set a boundary level of the preceding layer.

19. The process of claim 15 wherein the given layer comprises a plurality of given layers.

16-17. -17. (canceled)

20-21. -21. (canceled)

22. A fabrication process for forming a multi-layer three-dimensional structure, comprising:

(a) forming a first layer comprising at least one structural material and at least one sacrificial material;

(b) forming at least one additional layer from at least one structural material and at least one sacrificial material wherein the at least one additional layer is formed on and adhered to a previously formed layer, and wherein the first layer and the at least one additional layer together form a multi-layer three-dimensional structure; and

(c) after formation of a plurality of layers, separating at least a portion of the at least one sacrificial material on the plurality of layers from the at least one structural material on the plurality of layers,

wherein a given one of the layers comprises at least one sacrificial material and at least two structural materials, wherein the at least two structural materials comprise a core structural material that extends from a lower boundary level of the given layer to an upper boundary level of the given layer and a shell structural material that has side walls that extends from a lower boundary level of the given layer to an upper boundary level of the given layer such that the shell structural material encapsulates the sides of the core material on the given layer.

25. The process of claim 22 wherein a layer immediately preceding the given layer defines a capping layer comprising a capping structural material that provides a base that in combination with the shell structural material of the given layer completes encapsulation of the bottom and sides of the core material of the given layer and wherein the capping layer additionally comprises a sacrificial material that occupies at least a portion of the layer not occupied by the capping structural material, and wherein the capping structural material and sacrificial material on the preceding layer are planarized to set a boundary level of the preceding layer.

26. The process of claim 22 wherein a layer immediately succeeding the given layer defines a capping layer comprising a capping structural material that provides a cap that in combination with the shell structural material of the given layer completes encapsulation of the core material of the given layer and wherein the capping layer additionally comprises a sacrificial material that occupies at least a portion of the layer not occupied by the capping structural material, and wherein the capping structural material and sacrificial material on the succeeding layer are planarized to set a boundary level of the succeeding layer.

23-24. -24. (canceled)

27-28. -28. (canceled)

29. A fabrication process for forming a multi-layer three-dimensional structure, comprising:

(a) forming a first layer comprises at least one structural material and at least one sacrificial material;

(b) forming at least one additional layer from at least one structural material and at least one sacrificial material wherein the at least one additional layer is formed on and adhered to a previously formed layer, and wherein the first layer and the at least one additional layer together form a multi-layer three-dimensional structure; and

(c) after formation of a plurality of layers, separating at least a portion of the sacrificial material on the plurality of layers from the at least one structural material on on the plurality of layers,

wherein the forming of at least two layers comprises producing at portion of the structure from a core structural material and a shell structural material wherein the core material extends unbroken from a given layer to a subsequent layer and is surrounded by an unbroken barrier of shell structural material and wherein the subsequent layer is selected from the group consisting of (1) a layer immediately succeeding the given layer, (2) a layer that is separated from the given layer by an intermediate layer, (3) a layer that is separated from the given layer by at least two intermediate layers, and (4) a layer that is separated from the given layer by more than two intermediate layers, and wherein a width of a feature selected from the group consisting of the shell structural material and the core structural material is less than a minimum feature size associated with the formation of a layer containing the feature.

30. A fabrication process for forming a multi-layer three-dimensional structure or an array of structures, comprising:

(a) forming and adhering a layer of to an existing surface selected from the group consisting of a previously formed layer and a substrate, wherein the layer comprises at least one structural material and at least one sacrificial material;

(b) repeating the forming and adhering operation of (a) to build up a three-dimensional structure from a plurality of adhered layers, wherein the formation of at least one given layer comprises deposition of at least one sacrificial material and at least two structural materials at least one of which, the encapsulating structural material, at least partially encapsulates the other, the encapsulated structural material; and

(c) after formation of a plurality of layers, separating at least a portion of the sacrificial material forming a portion of the plurality of layers from the at least one structural material forming another portion of each of the plurality of layers,

wherein a selected one of the encapsulating structural material and the encapsulated structural material forming a portion of the given layer has a width less than the minimum feature size associated with the formation of the given layer.

52. The process of claim 30 wherein formation of the given layer comprises:

(i) applying a photoresist to a surface of a layer immediately preceding the given layer;

(ii) patterning and developing the photoresist to forming at least one opening in the photoresist where sacrificial material is to be deposited;

(iii) depositing the sacrificial material to form a portion of the given layer;

(iv) removing the photoresist to leave a void in the sacrificial material into which structural material is to be deposited;

(v) depositing the encapsulating structural material to a depth less than a desired thickness of the given layer such that a base and sidewalls of the encapsulating structural material are deposited;

(vi) depositing an encapsulated structural material to a depth that raises a net thickness of deposited structural material to a height that is at least as great as the desired thickness of the given layer;

(vii) planarizing the sacrificial material, the encapsulating structural material and the encapsulated structural material to a height that sets a boundary level for the given layer.

53. The process of claim 30 wherein the structure comprises a plurality of substantially identical structures that are being formed in a batch process simultaneously and wherein at least a portion of the depositing steps comprise electroplating steps.

54. The process of claim 53 wherein the structure comprises design features having micron scale dimensions.

31. The process of claim 31 wherein the encapsulated structural material is the same material as the sacrificial material and wherein the formation of the given layer and at least one immediately successive layer results in complete encapsulation of the encapsulated structural material on the given layer by the encapsulating structural material forming a portion of the given layer and an encapsulating structural material forming a portion of the immediately successive layer.

32. The process of claim 31 wherein each of the encapsulating and encapsulated structural material is different from the sacrificial material and wherein the formation of the given layer and at least one immediately successive layer results in complete encapsulation of a encapsulated structural material on the given layer by the encapsulating structural material forming a portion of the given layer and an encapsulating structural material forming a portion of the immediately successive layer.

33. The process of claim 31 wherein the forming and adhering comprises electrodepositing at least one material.

34. The process of claim 31 wherein the encapsulated material forming a portion of the given layer has a width that is less than the minimum feature size for the given layer.

35. The process of claim 31 wherein the at least one given layer comprises a plurality of layers.

36. The process of claim 35 wherein the plurality of given layers comprises a number of layers that is at least one less than the plurality of adhered layers.

37. The process of claim 31 wherein the forming of the given layer comprises defining at least two distinct locations for deposition of the encapsulated material and wherein the depositing of encapsulated material into the at least two locations comprises depositing at least two different materials.

38. The process of claim 31 wherein the encapsulated material has a higher conductivity than does the encapsulating material.

39. The process of claim 31 wherein the given layer is a compound layer and is formed from a first sub-layer and a second sub-layer having a common cross-sectional configuration of structural material and sacrificial material wherein the first sub-layer provides for a pocket of an encapsulated structural material bounded on the bottom and sides by the encapsulating structural material and wherein the second sub-layer provides for at least partial a partially capping of the pocket with a structural material that is different from the encapsulated structural material.

40. A fabrication process for forming a multi-layer three-dimensional probe structure or array of probe structures, comprising:

(a) forming and adhering a layer of material to an existing surface selected from the group consisting of a previously formed layer and a substrate, wherein the layer comprises at least one structural material and at least one sacrificial material;

(b) repeating the forming and adhering operation of (a) to build up a three-dimensional structure from a plurality of adhered layers, wherein the formation of at least a given layer comprises deposition of at least one sacrificial material and at least two structural materials, at least one of which, the encapsulating structural material, isolates other, the encapsulated structural material, from the sacrificial material; and

(c) after formation of a plurality of layers, separating at least a portion of the at least one sacrificial material forming a portion of plurality of layers from the at least one structural material forming another portion of the layers,

wherein the encapsulated material exists within a lower boundary and an upper boundary of the given layer and wherein the encapsulating material for the given layer has a width dimension that is less than a minimum feature size associated with forming the given layer.

41. The process of claim 40 wherein the encapsulated structural material is the same material as the sacrificial material and wherein the formation of the given layer and at least one immediately successive layer results in complete encapsulation of the encapsulated structural material on the given layer by a the encapsulating structural material forming a portion of the given layer and an encapsulating structural material forming a portion of the immediately successive layer.

42. The process of claim 40 wherein each of the encapsulating and encapsulated structural material is different from the sacrificial material and wherein the formation of the given layer and at least one immediately successive layer results in complete encapsulation of the encapsulated structural material on the given layer by the encapsulating structural material forming a portion of the given layer and an encapsulating structural material forming a portion of the immediately successive layer.

43. The process of claim 40 wherein the forming and adhering comprises electrodepositing at least one material.

44. The process of claim 40 wherein the at least one given layer comprises a plurality of given layers and wherein encapsulated structural material exists in at least one isolated pocket on each of the plurality of given layers.

46. The process of claim 40 wherein the forming of the given layer comprises defining at least two distinct locations for deposition of the encapsulated material and wherein the depositing of encapsulated material into the at least two locations comprises depositing at least two different materials.

47. The process of claim 40 wherein the encapsulated material has a higher conductivity than does the encapsulated material.

48. The process of claim 40 wherein the given layer is a compound layer and is formed from a first sub-layer and second sub-layer having a common cross-sectional configuration of structural material and sacrificial material wherein the first sub-layer provides for a pocket of an encapsulated material bounded on the bottom and sides by encapsulating structural material and wherein the second sub-layer provides for at least partial capping of the pocket with a structural material that is different from the encapsulated structural material.

55. The process of claim 40 wherein formation of the given layer comprises:

(i) applying a photoresist to a surface of a layer immediately preceding the given layer;

(ii) patterning and developing the photoresist to forming at least one opening in the photoresist where sacrificial material is to be deposited;

(iii) depositing the sacrificial material to form a portion of the given layer;

(iv) removing the photoresist to leave a void in the sacrificial material into which structural material is to be deposited;

(v) depositing the encapsulating structural material to a depth less than a desired thickness of the given layer such that a base and sidewalls of the encapsulating structural material are deposited;

(vi) depositing an encapsulated structural material to a depth that raises a net thickness of deposited structural material to a height that is at least as great as the desired thickness of the given layer;

(vii) planarizing the sacrificial material, the encapsulating structural material and the encapsulated structural material to a height that sets a boundary level for the given layer.

56. The process of claim 40 wherein the structure comprises a plurality of substantially identical structures that are being formed in a batch process simultaneously and wherein at least a portion of the depositing steps comprise electroplating steps.

57. The process of claim 56 wherein the structure comprises design features having micron scale dimensions.

45. The process of claim 45 wherein the plurality of given layers comprises a number of layers that is at least one less than the plurality of adhered layers.