Compliant bipolar micro device transfer head with silicon electrodes

• US 8,415,767 B1
• Filed: 07/06/2012
• Issued: 04/09/2013
• Est. Priority Date: 07/06/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: LuxVue Techonology Corporation (Apple Inc.)
• Inventors: Golda, Dariusz, Bibl, Andreas
• Primary Examiner(s): Stark, Jarrett
• Assistant Examiner(s): TOBERGTE, NICHOLAS J
• Application Number:
  US13/543,675
• Time in Patent Office: 277 Days
• Field of Search: 257/619, 257/623, 257/774, 257/E29.324, 438/39
• US Class Current: 257/619
• CPC Class Codes: B81C 99/002 Apparatus for assembling MEMS, e.g. micromanipulators micromanipulators per se B25J7/00
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate
• CPC Class Codes: H01L 2224/75725 in the upper part of the bonding apparatus, e.g. in the bonding head
• 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
• CPC Class Codes: H01L 24/95 at chip-level, i.e. with connecting carried out on a plurality of singulated devices, i.e. on diced chips
• 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 2924/12041 LED
• CPC Class Codes: H01L 2924/1461 MEMS

Abstract

A compliant bipolar micro device transfer head array and method of forming a compliant bipolar micro device transfer array from an SOI substrate are described. In an embodiment, a compliant bipolar micro device transfer head array includes a base substrate and a patterned silicon layer over the base substrate. The patterned silicon layer may include first and second silicon interconnects, and first and second arrays of silicon electrodes electrically connected with the first and second silicon interconnects and deflectable into one or more cavities between the base substrate and the silicon electrodes.

Claims

1. A compliant bipolar transfer head array comprising:

a base substrate;

a patterned silicon layer over the base substrate, the patterned silicon layer including a first silicon interconnect, a first array of silicon electrodes electrically connected with the first silicon interconnect, a second silicon interconnect, and a second array of silicon electrodes electrically connected with the second silicon interconnect, wherein each silicon electrode of the first and second arrays of silicon electrodes includes an electrode lead and a mesa structure, and each mesa structure protrudes above the first and second silicon interconnects and each silicon electrode is deflectable into a cavity between the base substrate and the silicon electrode, wherein the first and second arrays of silicon electrodes are aligned and electrically insulated from one another; and

a dielectric layer covering a top surface of each mesa structure of the first and second arrays of silicon electrodes.

2. The compliant bipolar transfer head array of claim 1, wherein each silicon electrode in the first and second arrays of silicon electrodes is deflectable into a cavity in the base substrate.

3. The compliant bipolar transfer head array of claim 2, wherein the first and second arrays of silicon electrodes are deflectable into the same cavity in the base substrate.

4. The compliant bipolar transfer head array of claim 3, wherein the first and second silicon interconnects are parallel.

5. The compliant bipolar transfer head array of claim 3, wherein the cavity wraps around an end of one of the first and second silicon electrodes.

6. The compliant bipolar transfer head array of claim 3, wherein the cavity wraps around an end of both the first silicon electrode and the second silicon electrode.

7. The compliant bipolar transfer head array of claim 1, wherein the first and second arrays of silicon electrodes form an array of supported beams spanning between the first and silicon interconnects.

8. The compliant bipolar transfer head array of claim 7, further comprising an array of oxide joints between the first and second arrays of silicon electrodes.

9. The compliant bipolar transfer head array of claim 8, wherein the patterned silicon layer is on and in direct contact with a buried oxide layer, and the oxide joints are on and in direct contact with the buried oxide layer.

10. The compliant bipolar transfer head array of claim 9, wherein the oxide joints are parallel to the first and second silicon interconnects.

11. The compliant bipolar transfer head array of claim 10, wherein the supported beams include bends.

12. The compliant bipolar transfer head array of claim 10, wherein the array of oxide joints separate the first and second arrays of silicon electrodes along a longitudinal length of the array of supported beams.

13. The compliant bipolar transfer head array of claim 9, wherein the oxide joints are perpendicular to the first and second silicon interconnects.

14. The compliant bipolar transfer head array of claim 9, wherein the array oxide joints separate the first and second arrays of silicon electrodes along a transverse width of the array of supported beams.

15. The compliant bipolar transfer head array of claim 1, wherein the first and second arrays of silicon electrodes form an array of cantilever beams between the first and silicon interconnects.

16. The compliant bipolar transfer head array of claim 15, wherein each silicon electrode of first and second arrays of silicon electrodes is a separate cantilever beam, and further comprising an open space between the mesa structures of the first and second arrays of silicon electrodes.

17. The compliant bipolar transfer head array of claim 15, wherein the cantilever beams include bends.

18. The compliant bipolar transfer head array of claim 17, wherein the cantilever beams span between the first and silicon interconnects, and further comprising an array of oxide joints between the first and second arrays of silicon electrodes.

19. The compliant bipolar transfer head array of claim 18, wherein the patterned silicon layer is on and in direct contact with a buried oxide layer, and the oxide joints are on and in direct contact with the buried oxide layer.

20. The compliant bipolar transfer head array of claim 18, wherein the array of oxide joints separate the first and second arrays of silicon electrodes along a longitudinal length of the array of cantilever beams.

21. The compliant bipolar transfer head array of claim 18, wherein the oxide joints are parallel to the first and second silicon interconnects.

22. The compliant bipolar transfer head array of claim 1, further comprising:

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

a first 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 first silicon interconnect and the first array of silicon electrodes; and

a second 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 second silicon interconnect and the second array of silicon electrodes.

23. The compliant bipolar transfer head array of claim 22, further comprising a first dielectric layer underneath the dielectric layer.

24. The compliant bipolar transfer head array of claim 23, wherein the first dielectric layer is at least partially laterally between the mesa structures of the first and second arrays of silicon electrodes.

25. The compliant bipolar transfer head array of claim 23, wherein the dielectric layer has a higher dielectric constant or dielectric breakdown strength than the first dielectric layer.

26. The compliant bipolar transfer head array of claim 1, wherein the base substrate is a bulk silicon substrate.

27. The compliant bipolar transfer head array of claim 1, wherein the base substrate is a (100) bulk silicon substrate.