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 selected micro devices in an array of micro devices, each micro device being bonded to a donor substrate with a donor force, the method comprising:
aligning the donor substrate and a receiver substrate so that each of the selected micro devices is in line with a contact pad on the receiver substrate;
positioning an adhesive layer between the selected micro devices and the receiver substrate; and
moving the donor substrate and the receiver substrate together until the selected micro devices are in contact with corresponding contact pads and the adhesive layer,
wherein a receiver force is generated by adhesion between the selected micro devices, the adhesive layer and the receiver substrate.
2. The method of claim 1 , further comprising:
selectively applying the adhesive layer to the contact pads associated with the selected micro devices.
3. The method of claim 1 , wherein the receiver force holds the selected micro devices to the corresponding selected contact pads, and the receiver force is generated by selectively applying the adhesive layer.
4. The method of claim 3 , further comprising:
selectively weakening, with laser lift off techniques, lapping, or a wet/dry etching, the donor force for the selected micro devices so that the donor force is less than the receiver force.
5. The method of claim 4 , wherein the donor force is weakened for all of the micro devices.
6. The method of claim 5 , wherein an adhesive force modulation is done by selective adhesive application to a selected force element on the receiver substrate and an order of the donor force and the receiver force modulation is changeable if the adhesive force modulation is not selective and the receiver force is larger than the donor force.
7. The method of claim 3 , wherein the adhesive layer is applied to the array of micro devices, the contact pads, the receiver substrate, or a combination thereof.
8. The method of claim 3 , wherein, if an electrical coupling exists between a micro device and its corresponding contact pad, the adhesive layer is selected for its conductivity.
9. The method of claim 8 , further comprising:
applying non-conductive adhesive layers near contact pads.
10. The method of claim 8 , further comprising:
applying non-conductive adhesive layers to cover only a portion of the contact pads.