Electromagnetic tool for transferring micro devices and methods of transfer

A method for transferring micro-devices, the method comprising:

• providing device structures over a first substrate;
• positioning an electromagnetic apparatus comprising head structures directly over the device structures;
• activating an electromagnet in the electromagnetic apparatus, the activating generating a magnetic flux in the head structures and magnetically coupling device structures proximal to the head structures;
• lifting and removing the device structures proximal to the head structures from the first substrate;
• placing the portion of the device structures proximal to the head structures onto a second substrate;
• de-activating the electromagnet;
• removing the electromagnetic apparatus away from second substrate;
• wherein the head structures have a spatial distribution that matches a desired spatial distribution of the device structures in the second substrate;
• and
• wherein the device structures not directly under the head structures are not magnetically coupled with the electromagnetic apparatus and left on the first substrate.

A method for transferring micro-devices, the method comprising:

• providing device structures on a first layer over a first substrate;
• placing an electromagnet over the device structures;
• activating the electromagnet and attracting the device structures to a surface of the electromagnet proximal to the device structures;
• immersing the first substrate and the device structures in a chemical solution;
• chemically dissolving and removing the first layer between the device structures and the first substrate;
• removing the device structures adjacent to the surface of the electromagnet from the chemical solution;
• providing a second substrate having a first adhesive layer;
• placing the device structures on the first adhesive layer;
• deactivating and removing the electromagnet, wherein the device structures adhere to the first adhesive layer;
• placing an electromagnetic apparatus comprising head structures directly over the device structures;
• activating the electromagnetic apparatus, the activating generating a magnetic flux in the head structures and magnetically coupling device structures proximal to the head structures;
• lifting and removing the device structures proximal to the head structures from the first adhesive layer;
• placing the device structures proximal to the head structures onto a second adhesive layer over a third substrate;
• and
• de-activating and removing the electromagnetic apparatus from the third substrate.