Micro device transfer head heater assembly and method of transferring a micro device
A method of transferring a micro device and an array of micro devices are disclosed. A carrier substrate carrying a micro device connected to a bonding layer is heated to a temperature below a liquidus temperature of the bonding layer, and a transfer head is heated to a temperature above the liquidus temperature of the bonding layer. Upon contacting the micro device with the transfer head, the heat from the transfer head transfers into the bonding layer to at least partially melt the bonding layer. A voltage applied to the transfer head creates a grip force which picks up the micro device from the carrier substrate.
1. A method comprising:
transferring heat from a heater assembly through a base substrate and to an array of transfer heads supported by the base substrate;
picking up an array of micro devices from a carrier substrate with an electrostatic transfer head assembly including the heater assembly and the base substrate supporting the array of electrostatic transfer heads;
contacting a receiving substrate with the array of micro devices, wherein the array of electrostatic transfer heads are at a temperature above 156.7° C. while initially contacting the receiving substrate with the array of micro devices; and
releasing the array of micro devices onto the receiving substrate.
2. The method of claim 1 , wherein each micro device has a maximum width of 1-100 microns.
3. The method of claim 2 , wherein each electrostatic transfer head includes a contact surface with a maximum width of 1-100 microns.
4. The method of claim 1 , wherein each electrostatic transfer head picks up a single micro device.
5. The method of claim 1 , wherein the array of electrostatic transfer heads includes an array of mesa structures protruding from the base substrate.
6. The method of claim 5 , wherein each electrostatic transfer head has a contact surface for picking up a single micro device and each electrostatic transfer head contact surface has a maximum width of 1-100 microns.
7. The method of claim 6 , wherein each micro device has a maximum width of 1-100 microns.
8. The method of claim 1 , wherein the array of micro devices are micro LED devices.
9. The method of claim 8 , further comprising bonding the array of micro LED devices to an array of driver contacts on the receiving substrate.
10. The method of claim 9 , wherein each micro LED device has a maximum width of 1-100 microns.
11. The method of claim 9 , wherein each micro LED device has a maximum width of 1-10 microns.
12. The method of claim 1 , wherein each electrostatic transfer head generates a grip pressure of 2 to 20 atmospheres on a respective micro device while picking up the array of micro devices.
13. The method of claim 1 , wherein each electrostatic transfer head is a bipolar electrostatic transfer head, and further comprising applying alternating voltages across the array of bipolar electrostatic transfer heads when picking up an array of micro devices from the carrier substrate and contacting the receiving substrate with the array of micro devices.
14. The method of claim 13 , wherein the array of electrostatic transfer heads includes an array of mesa structures protruding from the base substrate.
15. The method of claim 14 , wherein each electrostatic transfer head has a contact surface for picking up a single micro device and each electrostatic transfer head contact surface has a maximum width of 1-100 microns.
16. The method of claim 15 , wherein each electrostatic transfer head generates a grip pressure of 2 to 20 atmospheres on a respective micro device while picking up the array of micro devices.