Selective micro device transfer to receiver substrate
A method of selectively transferring micro devices from a donor substrate to contact pads on a receiver substrate. Micro devices being attached to a donor substrate with a donor force. The donor substrate and receiver substrate are aligned and brought together so that selected micro devices meet corresponding contact pads. A receiver force is generated to hold selected micro devices to the contact pads on the receiver substrate. The donor force is weakened and the substrates are moved apart leaving selected micro devices on the receiver substrate. Several methods of generating the receiver force are disclosed, including adhesive, mechanical and electrostatic techniques.
1. A method of transferring micro devices from a temporary substrate into a backplane, the method comprising:
depositing a buffer layer on a temporary substrate;
transferring the micro devices from a first substrate to the temporary substrate;
removing the first substrate; and
transferring the micro devices from the temporary substrate to the backplane by applying a receiver force where the buffer layer causes the force between micro-devices and temporary substrate to be weaker than the receiver force.
2. The method of claim 1 , wherein the buffer layer is a polyamide layer.
3. The method of claim 1 , wherein, when the buffer layer is not conductive, further comprising:
depositing and patterning an electrode before or after the buffer layer to enable testing of the micro devices after the transferring from the temporary substrate to the backplane.
4. The method of claim 3 , wherein, if the electrode is deposited before the buffer layer, the buffer layer is patterned to create an opening for a contact.
5. The method of claim 1 , wherein two connections required for a microdevice are on a transfer side and the micro device is in full contact with the backplane after the transfer process.
6. The method of claim 1 , wherein a top electrode is deposited and patterned.
7. The method of claim 6 , wherein a polarization layer is used before depositing the electrode.
8. The method of claim 7 , wherein after the deposition, the polarization layer is patterned to create an opening for connecting the top electrode layer to system substrate contacts wherein the contacts are separated for each LED or shared.
9. The method of claim 8 , wherein optical enhancement layers are deposited before or after the top electrode deposition.
10. A method of transferring micro devices from a temporary substrate into a backplane, the method comprising:
providing a first pitch of micro devices in the temporary substrate different from a second pitch of micro devices in the backplane;
transferring the micro devices from the temporary substrate to the backplane by a receiver force while a holding force holding the micro devices in the temporary substrate is reduced after the temporary substrate and the backplane are in contact by depositing a buffer layer on the temporary substrate.
11. The method of claim 10 , wherein further, a pressure is applied using a flat surface in a post-processing step to the micro devices while a temperature is increased to increase a connection reliability to the backplane.
12. The method of claim 10 , wherein two connections required for a microdevice are on a transfer side and the micro device is in full contact with the backplane after the transfer process.
13. The method of claim 10 , wherein a top electrode is deposited and patterned.
14. The method of claim 13 , wherein a polarization layer is used before depositing the electrode.
15. Me method of claim 14 , wherein after the deposition, the polarization layer is patterned to create an opening for connecting the top electrode layer to system substrate contacts wherein the contacts are separated for each LED or shared.
16. The method of claim 15 , wherein optical enhancement layers are deposited before or after the top electrode deposition.
17. The method of claim 10 , wherein the method further comprises applying pressure using a flat surface in a post-processing step to the micro devices while a temperature is increased to increase a connection reliability to the backplane.