Compliant bipolar micro device transfer head with silicon electrodes
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.
1. A transfer head array comprising:
a base substrate; and
an array of compliant transfer heads;
wherein each compliant transfer head comprises a double sided clamped beam that extends across a cavity from a first side of the cavity to a second side of the cavity, and a mesa structure supported by the double sided clamped beam, wherein the mesa structure protrudes from the double sided clamped beam over the cavity to provide a localized contact point for the compliant transfer head; and
wherein each double sided clamped beam comprises:
a first beam length extending from the first side of the cavity;
a second beam length extending from the second side of the cavity;
wherein the first beam length is joined to the second beam length over the cavity;
a first 180 degree bend along the first beam length that extends from the first side of the cavity to the second beam length; and
a second 180 degree bend along the second beam length that extends from the second side of the cavity to the second beam length.
2. The transfer head array of claim 1 , wherein the first 180 degree bend includes a first pair of bends.
3. The transfer had array of claim 2 , wherein the second 180 degree bend includes a second pair of bends.
4. The transfer head array of claim 1 , wherein the double sided clamped beam is in an S-shape configuration, with a first end of the S-shape configuration extending from the first side of the cavity and a second end of the S-shape configuration extending from the second side of the cavity.
5. The transfer head array of claim 1 , wherein the double sided clamped beam is in a W-shape configuration, with a first end of the W-shape configuration extending from the first side of the cavity and a second end of the W-shape configuration extending from the second side of the cavity.
6. The transfer head array of claim 1 , further comprising a dielectric layer covering the mesa structure of each compliant transfer head.
7. The transfer head array of claim 1 , wherein each double sided clamped beam extends across the same cavity.
8. The transfer head array of claim 1 , wherein each double sided clamped beam extends across a separate cavity.
9. The transfer head array of claim 1 , wherein each double sided clamped beam comprises a pair of protruding mesa structures over the cavity to provide the localized contact point for the compliant transfer head, the pair of protruding mesa structures including the protruding mesa structure and a second protruding mesa structure, wherein the protruding mesa structure protrudes from the first beam length and the second protruding mesa structure protrudes from the second beam length.
10. The transfer head array of claim 9 , wherein the first 180 degree bend includes a first pair of bends.
11. The transfer had array of claim 10 , wherein the second 180 degree bend includes a second pair of bends.
12. The transfer head array of claim 9 , wherein the double sided clamped beam is in an S-shape configuration, with a first end of the S-shape configuration extending from the first side of the cavity and a second end of the S-shape configuration extending from the second side of the cavity.
13. The transfer head array of claim 9 , wherein the double sided clamped beam is in a W-shape configuration, with a first end of the W-shape configuration extending from the first side of the cavity and a second end of the W-shape configuration extending from the second side of the cavity.
14. The transfer head array of claim 9 , further comprising a dielectric layer covering the pair of mesa structures of each compliant transfer head.
15. The transfer head array of claim 14 , wherein the dielectric layer is formed between the pair of mesa structures of each compliant transfer head.
16. The transfer head array of claim 14 , further comprising a dielectric joint between the protruding mesa structure and the second protruding mesa structure of each compliant transfer head.
17. The transfer head array of claim 16 , wherein the dielectric layer is formed over the dielectric joint.
18. The transfer head array of claim 17 , wherein the dielectric layer is formed of a different material than the dielectric joint.
19. The transfer head array of claim 9 , wherein each double sided clamped beam extends across the same cavity.
20. The transfer head array of claim 9 , wherein each double sided clamped beam extends across a separate cavity.