Compliant micro device transfer head

• US 9,105,492 B2
• Filed: 05/08/2012
• Issued: 08/11/2015
• Est. Priority Date: 05/08/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: LuxVue Techonology Corporation (Apple Inc.)
• Inventors: Bibl, Andreas, Higginson, John A., Hu, Hsin-Hua
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): PLUMB, NIGEL H
• Application Number:
  US13/466,966
• Publication Number:
  US 20130300812A1
• Time in Patent Office: 1,190 Days
• Field of Search: 361/234, 438/110, 438/608, 228/180.21, 356/301, 257/416, 250/221, 345/173, 347/159
• US Class Current: 1/1
• CPC Class Codes: B25J 15/0052 multiple gripper units or multiple end effectors
• CPC Class Codes: B25J 15/0085 with means for applying an electrostatic force on the object to be gripped
• CPC Class Codes: B41J 2/385 characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material B41J2/005 takes precedence
• CPC Class Codes: B41J 2/39 using multi-stylus heads
• CPC Class Codes: B81B 2201/038 Microengines and actuators not provided for in B81B2201/031 - B81B2201/037
• CPC Class Codes: B81C 99/002 Apparatus for assembling MEMS, e.g. micromanipulators micromanipulators per se B25J7/00
• CPC Class Codes: H01L 21/67144 Apparatus for mounting on conductive members, e.g. leadframes or conductors on insulating substrates
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/68322 Auxiliary support including means facilitating the selective separation of some of a plurality of devices from the auxiliary support
• CPC Class Codes: H01L 2221/68354 used to support diced chips prior to mounting
• CPC Class Codes: H01L 2221/68363 used in a transfer process involving transfer directly from an origin substrate to a target substrate without use of an intermediate handle substrate
• CPC Class Codes: H01L 2221/68368 used in a transfer process involving at least two transfer steps, i.e. including an intermediate handle substrate
• CPC Class Codes: H01L 2221/68381 Details of chemical or physical process used for separating the auxiliary support from a device or wafer
• CPC Class Codes: H01L 2224/29036 covering only the central area of the surface to be connected
• CPC Class Codes: H01L 2224/29101 the principal constituent melting at a temperature of less than 400°C
• CPC Class Codes: H01L 2224/2919 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/7565 Means for transporting the components to be connected
• CPC Class Codes: H01L 2224/7598 specially adapted for batch processes
• CPC Class Codes: H01L 2224/83 using a layer connector
• CPC Class Codes: H01L 2224/83815 Reflow soldering
• CPC Class Codes: H01L 2224/83855 : Hardening the adhesive by curing, i.e. thermosetting
• CPC Class Codes: H01L 2224/95001 : involving a temporary auxiliary member not forming part of the bonding apparatus, e.g. removable or sacrificial coating, film or substrate
• CPC Class Codes: H01L 2224/97 : the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 24/75 : Apparatus for connecting with bump connectors or layer connectors
• CPC Class Codes: H01L 24/83 : using a layer connector
• CPC Class Codes: H01L 24/97 : the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 25/0753 : the devices being arranged next to each other
• 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 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 33/0093 : Wafer bonding; Removal of the growth substrate

Abstract

A compliant micro device transfer head and head array are disclosed. In an embodiment a micro device transfer head includes a spring portion that is deflectable into a space between a base substrate and the spring portion.

Claims

1. A micro device transfer head comprising:

a base substrate;

a spring member including;

a spring anchor coupled to the base substrate; and

a spring portion comprising an electrode, wherein the spring portion is deflectable into a space between the spring portion and the base substrate;

a dielectric layer covering a top surface of the electrode; and

a sensor integrated with the spring member to measure an amount of deflection of the spring portion.

2. The micro device transfer head of claim 1, wherein the spring portion further comprises a mesa structure protruding away from the base substrate.

3. The micro device transfer head of claim 2, wherein the mesa structure is integrally formed with the spring portion.

4. The micro device transfer head of claim 2, further comprising an electrode lead running from the electrode to the spring anchor of the spring member.

5. The micro device transfer head of claim 4, wherein the electrode lead runs along a top surface of the spring member.

6. The micro device transfer head of claim 5, wherein the dielectric layer covers the electrode lead along the top surface of the spring member.

7. The micro device transfer head of claim 4, further comprising a via through the mesa structure connecting the electrode to the electrode lead.

8. The micro device transfer head of claim 1, wherein the sensor comprises a material selected from a group consisting of a piezoelectric material and a piezoresistive material.

9. The micro device transfer head of claim 1, wherein the sensor is coupled to the spring member.

10. The micro device transfer head of claim 1, wherein the sensor is formed within the spring member.

11. The micro device transfer head of claim 1, wherein the sensor comprises a first electrode on a bottom surface of the spring portion and a second electrode formed on the base substrate within the space and opposite the first electrode.

12. The micro device transfer head of claim 1, wherein the sensor is selected from a group consisting of a capacitive sensor and a strain gauge.

13. The micro device transfer head of claim 2, wherein the space is a cavity in the base substrate.

14. The micro device transfer head of claim 13, wherein the spring member is a spring arm having a first end coupled to the base substrate and a second end suspended above the cavity, wherein the first end comprises the spring anchor and the second end comprises the spring portion.

15. The micro device transfer head of claim 13, wherein the spring member completely covers the cavity.

16. The micro device transfer head of claim 15, wherein the mesa structure is formed over a center of the cavity.

17. The micro device transfer head of claim 2, further comprising a second electrode on the top surface of the mesa structure to form a pair of electrodes, wherein the dielectric layer covers the pair of electrodes.

18. The micro device transfer head of claim 1, wherein the spring portion is elevated above the base substrate by the spring anchor.

19. The micro device transfer head of claim 18, wherein the spring member is a spring arm.

20. The micro device transfer head of claim 1, wherein the spring member comprises a plurality of spring arms.

21. A micro device transfer head array comprising:

an array of transfer heads, each comprising;

a base substrate;

a spring member including;

a spring anchor coupled to the base substrate; and

a spring portion comprising an electrode, wherein the spring portion is deflectable into a space between the spring portion and the base substrate;

a dielectric layer covering a top surface of the electrode; and

a sensor integrated with the spring member to measure an amount of deflection of the spring portion.

22. The micro device transfer head array of claim 21, wherein the space of each transfer head is a cavity in the base substrate.

23. The micro device transfer head array of claim 22, wherein the spring member is a spring arm having a first end coupled to the base substrate and a second end suspended above the cavity, wherein the first end comprises the spring anchor and the second end comprises the spring portion.

24. The micro device transfer head array of claim 22, wherein the spring member completely covers the cavity.

25. The micro device transfer head array of claim 21, wherein the sensor comprises a material selected from a group consisting of a piezoelectric material and a piezoresistive material.

26. A method of transferring an array of micro devices comprising:

depressing each transfer head in an array of transfer heads, each transfer head comprising;

a base substrate;

a spring member including;

a spring anchor coupled to the base substrate; and

a spring portion comprising an electrode, wherein the spring portion is deflectable into a space between the spring portion and the base substrate; and

a dielectric layer covering a top surface of the electrode;

applying a voltage to each transfer head to maintain the depressed position;

removing the voltage from a portion of the transfer heads to selectively release the portion of the transfer heads from the depressed position to form a selectively-released array of transfer heads;

positioning the selectively-released array of transfer heads over an array of micro devices;

contacting the array of micro devices with the selectively-released array of transfer heads;

picking up a portion of the array of micro devices corresponding to the released portion of transfer heads in the selectively-released array of transfer heads; and

releasing the portion of the array of micro devices onto at least one receiving substrate.

27. The method of claim 26, wherein the transfer head further comprises:

a backside electrode on the bottom surface of the spring portion;

an opposing electrode on the base substrate within the space and opposite the backside electrode; and

a dielectric layer formed over the surface of the opposing electrode.