Micro device transfer head with silicon electrode

• US 8,415,771 B1
• Filed: 05/25/2012
• Issued: 04/09/2013
• Est. Priority Date: 05/25/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: LuxVue Techonology Corporation (Apple Inc.)
• Inventors: Golda, Dariusz, Bibl, Andreas
• Primary Examiner(s): Malsawma, Lex
• Application Number:
  US13/481,592
• Time in Patent Office: 319 Days
• Field of Search: 257/621, 257/626, 257/E23.169, 257/E23.174
• US Class Current: 257/621
• CPC Class Codes: B81C 2201/0194 the layer being structured
• CPC Class Codes: B81C 99/0025 Apparatus specially adapted for the manufacture or treatment of microstructural devices or systems not provided for in B81C99/001 - B81C99/002
• CPC Class Codes: H01L 21/67144 Apparatus for mounting on conductive members, e.g. leadframes or conductors on insulating substrates
• CPC Class Codes: H01L 2224/7598 specially adapted for batch processes
• CPC Class Codes: H01L 24/75 Apparatus for connecting with bump connectors or layer connectors

Abstract

A micro device transfer head array and method of forming a micro device transfer array from an SOI substrate are described. In an embodiment, the micro device transfer head array includes a base substrate and a patterned silicon layer over the base substrate. The patterned silicon layer may include a silicon interconnect and an array of silicon electrodes electrically connected with the silicon interconnect. Each silicon electrode includes a mesa structure protruding above the silicon interconnect. A dielectric layer covers a top surface of each mesa structure.

Claims

1. A micro device transfer head array comprising:

a base substrate;

a patterned silicon layer over the base substrate, the patterned silicon layer including a silicon interconnect and an array of silicon electrodes electrically connected with the silicon interconnect, wherein each silicon electrode includes a mesa structure protruding above the silicon interconnect; and

a dielectric layer covering a top surface of each mesa structure;

wherein the array of silicon electrodes are integrated into a corresponding array of electrostatic transfer heads, each electrostatic transfer head configured to transfer a separate micro device.

2. The micro device transfer head array of claim 1, wherein each silicon electrode further comprises an electrode lead.

3. The micro device transfer head array of claim 1, further comprising a via extending through the base substrate from a backside of the base substrate to the patterned silicon layer, and in electrical connection with the silicon interconnect and the array of silicon electrodes.

4. The micro device transfer head array of claim 3, further comprising a passivation layer covering a side surface of the via within the base substrate.

5. The micro device transfer head array of claim 4, wherein the via terminates at a bottom surface of the patterned silicon layer.

6. The micro device transfer head array of claim 5, further comprising a conductive layer on the passivation layer and in electrical contact with the bottom surface of the patterned silicon layer.

7. The micro device transfer head array of claim 6, wherein the conductive layer does not completely fill the via.

8. The micro device transfer head array of claim 4, wherein the via extends through the patterned silicon layer.

9. The micro device transfer head array of claim 8, further comprising a conductive layer on the passivation layer and in electrical contact with an interior side surface of the patterned silicon layer.

10. The micro device transfer head array of claim 9, wherein a portion of conductive layer partially covers a top surface of the patterned silicon layer.

11. The micro device transfer head array of claim 10, wherein the conductive layer does not completely fill the via.

12. The micro device transfer head array of claim 10, wherein the portion of the conductive layer partially covering the top surface of the patterned silicon layer has a different thickness than the conductive layer on the passivation layer.

13. The micro device transfer head array of claim 4, wherein the side surface of the via is tapered so that the via is wider at the bottom surface of the base substrate than at a top surface of the base substrate.

14. The micro device transfer head array of claim 4, further comprising an silicon oxide layer between the patterned silicon layer and the base substrate, and wherein the via extends through the silicon oxide layer.

15. The micro device transfer head array of claim 3, further comprising:

a second via extending through the base substrate from the backside of the base substrate to the patterned silicon layer, and in electrical connection with a second silicon interconnect and a second array of silicon electrodes;

wherein each silicon electrode in the second array of silicon electrodes includes a mesa structure protruding above the second silicon interconnect, and the dielectric layer coves a top surface of each mesa structure.

16. The micro device transfer head array of claim 15, wherein the array of silicon electrodes, and the second array of silicon electrodes are aligned to form an array of bipolar silicon electrodes.

17. The micro device transfer head array of claim 15, wherein the via and the second via terminate at a bottom surface of the patterned silicon layer.

18. The micro device transfer head array of claim 15, wherein the via and the second via extend through the patterned silicon layer.

19. The micro device transfer head array of claim 15, further comprising a first dielectric layer on the patterned silicon layer, wherein the first dielectric layer is removed from over the mesa structures.

20. The micro device transfer head array of claim 19, wherein the dielectric layer covering the top surface of the each mesa structure has a higher dielectric constant or dielectric breakdown strength than the first dielectric layer.

21. The micro device transfer head array of claim 1, wherein the dielectric layer comprises a material selected from the group consisting of silicon oxide, hafnium oxide, aluminum oxide, and tantalum oxide.

22. The micro device transfer head array of claim 21, further comprising a via extending through the base substrate from a backside of the base substrate to the patterned silicon layer, and in electrical connection with the silicon interconnect and the array of silicon electrodes, wherein the dielectric layer is partially formed within the via.

23. The micro device transfer head array of claim 1, wherein the base substrate is a bulk silicon substrate.

24. The micro device transfer head array of claim 1, wherein the base substrate is a (100) bulk silicon substrate.

25. The micro device transfer head array of claim 1, wherein the patterned silicon layer is doped.

26. The micro device transfer head array of claim 25, wherein the patterned silicon layer is doped with an n-type dopant.

27. The micro device transfer head array of claim 26, wherein the patterned silicon layer is doped with phosphorus.

28. The micro device transfer head array of claim 1, further comprising:

a buried silicon oxide layer between the patterned silicon layer and the base substrate,

a via extending through the base substrate and the buried silicon oxide layer from a backside of the base substrate to the patterned silicon layer, and in electrical connection with the silicon interconnect and the array of silicon electrodes;

a silicon oxide passivation layer covering a side surface of the via within the base substrate;

wherein the base substrate is silicon.

29. The micro device transfer head array of claim 28, wherein the via extends through the patterned silicon layer.

30. The micro device transfer head array of claim 28, wherein the dielectric layer comprise a material selected from the group consisting of silicon oxide, hafnium oxide, aluminum oxide, and tantalum oxide.