Xerographic micro-assembler

• US 20060128057A1
• Filed: 12/14/2004
• Published: 06/15/2006
• Est. Priority Date: 12/14/2004
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Chow, Eugene M., Lu, Jeng Ping
• Granted Patent: US 7,332,361 B2
• Time in Patent Office: Days
• US Class Current: 438/106
• CPC Class Codes: H01L 21/67271 Sorting devices
• CPC Class Codes: H01L 21/67282 Marking devices
• CPC Class Codes: H01L 21/67294 using identification means, e.g. labels on substrates or labels on containers
• CPC Class Codes: H01L 2224/95085 being a liquid, e.g. for fluidic self-assembly
• CPC Class Codes: H01L 2224/95101 in a liquid medium
• CPC Class Codes: H01L 2224/95144 Magnetic alignment, i.e. using permanent magnetic parts in the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/95145 Electrostatic alignment, i.e. polarity alignment with Coulomb charges
• CPC Class Codes: H01L 24/95 at chip-level, i.e. with connecting carried out on a plurality of singulated devices, i.e. on diced chips
• CPC Class Codes: H01L 25/50 Multistep manufacturing processes of assemblies consisting of devices, each device being of a type provided for in group H01L27/00 or H01L29/00 H01L21/50 takes precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/1461 MEMS
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49133 with component orienting
• CPC Class Codes: Y10T 29/53004 with means to regulate operation by use of templet, tape, card or other replaceable information supply
• CPC Class Codes: Y10T 29/5313 Means to assemble electrical device
• CPC Class Codes: Y10T 29/53174 Means to fasten electrical component to wiring board, base, or substrate
• CPC Class Codes: Y10T 29/53178 Chip component
• CPC Class Codes: Y10T 29/53278 Storage cell or battery

Abstract

Xerographic micro-assembler systems and methods are disclosed. The systems and methods involve manipulating charge-encoded micro-objects. The charge encoding identifies each micro-object and specifies its orientation for sorting. The micro-objects are sorted in a sorting unit so that they have defined positions and orientations. The sorting unit has the capability of electrostatically and magnetically manipulating the micro-objects based on their select charge encoding. The sorted micro-objects are provided to an image transfer unit. The image transfer unit is adapted to receive the sorted micro-objects, maintain them in their sorted order and orientation, and deliver them to a substrate. Maintaining the sorted order as the micro-objects are delivered to the substrate may be accomplished through the use of an electrostatic image, as is done in xerography. The substrate with the micro-objects is further processed to interconnect the micro-objects—through electrical wiring, for example—to form the final micro-assembly.

Claims

1. A method of forming a micro-assembly, comprising:

sorting and orienting a plurality of micro-objects;

providing the sorted and oriented micro-objects to an image transfer unit;

transferring the sorted and oriented micro-objects from the image transfer unit to a substrate; and

fixing the transferred micro-objects to the substrate to form a micro-assembly.

2. The method of claim 1, wherein the image transfer unit includes a rotatable drum having an outer surface that supports an electrostatic image, and further including:

providing a select electrostatic image to the drum outer surface; and

securing the micro-objects to the outer surface via the select electrostatic image while transferring the micro-objects to the substrate.

3. The method of claim 1, including encoding some or all of the micro-objects with a patterned charge, and wherein said sorting and orienting includes electrically and/or magnetically manipulating the micro-objects based on the charge.

4. The method of claim 3, including sorting the charge-encoded micro-objects by providing a dynamic electrostatic field matched to the encoded charge.

5. The method of claim 1, including:

forming the micro-objects in a semiconductor wafer; and

dicing the semiconductor wafer.

6. The method of claim 5, further including forming a charge-encoded pattern on the micro-objects prior to dicing.

7. The method of claim 5, further including forming a charge-encoded pattern by inkjet printing.

8. The method of claim 1, wherein some or all of the micro-objects are selectively charge-encoded, and wherein the sorting includes:

suspending the micro-objects in a liquid medium; and

conveying some or all micro-objects from the liquid to the image transfer unit via a dynamic electrostatic field matched to the selectively charge-encoded micro-objects.

9. The method of claim 1, including:

forming the micro-objects to have an encoded charge;

subjecting the charge-encoded micro-objects to a dynamic electrostatic field matched to some or all of the charge-encoded micro-objects so as to orient and convey said some or all micro-objects to the image transfer unit.

10. The method of claim 9, including:

providing the dynamic electrostatic field with a transport field that moves some or all of the micro-objects toward the image transfer unit and;

providing the dynamic electrostatic field with an annealing field that randomly fluctuates.

11. The method of claim 10, further including moving the annealing field away from the image transfer unit.

12. The method of claim 10, wherein the transport field and the annealing field have respective strengths, and further including spatially varying the strength of the transport field and the strength of the annealing field to reduce movement of the micro-objects as the micro-objects get closer to the image transfer unit.

13. The method of claim 1, further including after said transferring:

electrically connecting two or more of the micro-objects.

14. The method of claim 1, further including charge-encoding the micro-objects by adding charge-encoding elements to microchips formed in a wafer prior to the wafer being diced into the microchips.

15. The method of claim 13, further including after said transferring:

removing the charge-encoding elements from the micro-objects.

16. The method of claim 15, further including:

planarizing the micro-objects and the substrates to expose a portion of corresponding micro-bodies with the micro-objects; and

operably interconnecting the micro-bodies.

17. The method of claim 1, including providing the micro-objects as sets of different micro-objects with different charge-encoded patterns.

18. A method of forming a micro-assembly, comprising:

encoding each of one or more micro-objects with a patterned charge that identifies each micro-object and specifies its orientation;

sorting the charge-encoded micro-objects based on their encoded charge;

providing the sorted charge-encoded micro-objects to a xerographic imaging unit adapted to receive and carry the sorted charge-encoded micro-objects;

transferring the sorted charge-encoded micro-objects from the xerographic imaging unit to a substrate; and

fixing the transferred micro-objects to the substrate to form a micro-assembly.

19. The method of claim 18, including providing an electrostatic image to the xerographic imaging unit to facilitate maintaining said sorting during said transferring.

20. The method of claim 18, including providing the xerographic imaging unit with a conveyor.

21. The method of claim 20, including providing the xerographic imaging unit with a drum adapted to support an electrostatic image.

22. The method of claim 18, including manipulating the micro-objects using a dynamic electrostatic field.

23. The method of claim 22, including manipulating the micro-objects using a magnetic field.

24. A micro-assembler apparatus for forming a micro-assembly from one or more micro-objects each having an encoded charge, comprising:

a sorting unit adapted to receive and sort micro-objects based on their charge encoding; and

an image transfer unit adapted to receive the sorted, charge-encoded micro-objects, maintain said sorting, and selectively deliver the sorted micro-objects to a substrate to form the micro-assembly.

25. The apparatus of claim 24, further including a post-processing unit adapted to receive the substrate and operably interconnect the micro-objects.

26. The apparatus of claim 25, wherein the post-processing unit is adapted to deliver electrically conductive material to the micro-objects in order to electrically interconnect the micro-objects.

27. The apparatus of claim 24, wherein the image transfer unit includes a conveyor belt.

28. The apparatus of claim 24, wherein the image transfer unit includes a transfer drum having an outer surface capable of supporting an electrostatic image that serves to hold the charge-encoded micro-objects to the transfer drum outer surface during the selective delivery of the micro-objects to the substrate.

29. The apparatus of claim 24, wherein the sorting unit includes a conveying unit adapted to create a dynamic electrostatic field to move select micro-objects to the image transfer unit.

30. The apparatus of claim 29, further including an electromagnet in magnetic communication with the conveying unit and adapted to manipulate micro-objects adapted to respond to a magnetic field.

31. The apparatus of claim 24, further including one or more pre-processing units operably coupled to the sorting unit and adapted to provide corresponding one or more types of micro-objects to the sorting unit.

32. A micro-assembler apparatus for forming a micro-assembly from one or more micro-objects, comprising:

an image transfer unit adapted to receive sorted charge-encoded micro-objects, maintain said sorting, and selectively deliver the sorted micro-objects to a substrate; and

a post-processing unit adapted to receive the substrate with the sorted micro-objects and fix the micro-objects to the substrate to form the micro-assembly.

33. The apparatus of claim 32, wherein the post-processing unit is further adapted to provide metal wiring to the micro-objects to electrically interconnect the micro-objects in the form of microchips.

34. The apparatus of claim 33, wherein the image transfer unit includes a photoreceptive conveyor, and wherein the apparatus further includes an optical release device in optical communication with the photoreceptive conveyor to provide for the optical release of the micro-objects carried by the conveyor for the delivery of the micro-objects to the substrate.

35. The apparatus of claim 34, further including:

a machine vision system in visual communication with the conveyor;

a controller operably coupled to the optical release devices and to the machine vision system, wherein the controller is adapted to receive information about the position of micro-objects on the conveyor and activate the optical release device based on said information for said delivery of the micro-objects to the substrate.

36. The apparatus of claim 34, wherein the photoreceptive conveyor is adapted to receive micro-objects adhered to a releasable-adhesive substrate that maintains the micro-objects in a pre-sorted arrangement.

37. The apparatus of claim 32, wherein:

the image transfer unit includes a first conveyor adapted to receive the sorted micro-objects, and at least a second conveyor operating at right angles to the first conveyor and adapted to receive select micro-objects photo-released from the first conveyor.