SYSTEMS AND METHODS FOR PREPARING GAN AND RELATED MATERIALS FOR MICRO ASSEMBLY

• US 20150372187A1
• Filed: 06/18/2015
• Published: 12/24/2015
• Est. Priority Date: 06/18/2014
• Status: Active Grant

• Current Assignee: X Display Company Technology Limited (Sensinnovat BVBA)
• Original Assignee: X-Celeprint Limited
• Inventors: Bower, Christopher, Meitl, Matthew
• Granted Patent: US 9,761,754 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/187 by direct bonding
• CPC Class Codes: H01L 21/2007 Bonding of semiconductor wafers to insulating substrates or to semiconducting substrates using an intermediate insulating layer H01L21/2011 takes precedence; bonding of semiconductor wafers to semiconductor wafers for junction formation H01L21/187
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 21/7806 involving the separation of the active layers from a substrate
• CPC Class Codes: H01L 2221/68354 used to support diced chips prior to mounting
• 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 2224/81805 involving forming a eutectic alloy at the bonding interface
• CPC Class Codes: H01L 24/81 using a bump connector
• 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 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/13055 Insulated gate bipolar transistor [IGBT]
• CPC Class Codes: H01L 2933/0025 relating to coatings
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

The disclosed technology relates generally to a method and system for micro assembling GaN materials and devices to form displays and lighting components that use arrays of small LEDs and high-power, high-voltage, and or high frequency transistors and diodes. GaN materials and devices can be formed from epitaxy on sapphire, silicon carbide, gallium nitride, aluminum nitride, or silicon substrates. The disclosed technology provides systems and methods for preparing GaN materials and devices at least partially formed on several of those native substrates for micro assembly.

Claims

1. A method of preparing released or releasable structures from a silicon native substrate, the method comprising:

depositing one or more members selected from the group consisting of GaN, AlGaN, InGaN, InGaAlN, and SiN on a substrate comprising Si (1 1 1), thereby forming an epitaxial material;

forming devices using the epitaxial material on the substrate;

delineating releasable structures comprising the devices in the epitaxial material, thereby partially exposing the substrate;

forming anchoring structures and tethering structures such that the releasable structures connect the devices to the substrate by the anchoring structures and tethering structures following contact of the substrate with the etchant;

removing silicon material underneath the releasable structures with an etchant , thereby forming printable structures comprising the devices, wherein a spatial orientation of the printable structures is maintained by the tether structures and anchor structures; and

exposing the substrate and the printable structures connected to the substrate by anchoring structures and/or tethering structures to one or more chemical agents for conditioning the newly exposed surface of the released structures.

2. The method of claim 1, wherein exposing the substrate and the printable structures to one or more chemical agents comprises exposure to heated phosphoric acid.

3. The method of claim 1, wherein exposing the substrate and the printable structures to one or more chemical agents imparts surface roughness to the newly exposed surface.

4. The method of claim 1, wherein the etchant is heated tetramethyl ammonium hydroxide, potassium hydroxide, sodium hydroxide or a basic solution for performing anisotropic silicon etch.

5. The method of claim 1, wherein forming devices comprises depositing and/or patterning a dielectric and/or conductive thin film.

6. The method of claim 1, wherein the anchoring structures and tethering structures are formed in the epitaxial material.

7. The method of claim 1, wherein the anchoring and tethering structures are formed from non-epitaxial material.

8. The method of claim 1, wherein the non-epitaxial material comprises one or more epitaxial materials selected from the group consisting of silicon nitride, silicon oxide.

9. The method of claim 1, comprising forming one or more encapsulating structures to encapsulate at least a portion of the printable structure.

10. The method of claim 1, comprising:

prior to removing silicon material underneath the structures, forming recesses in the exposed silicon.

11. The method of claim 1, wherein forming recesses in the exposed silicon comprises etching the exposed silicon.

12. The method of claim 1, comprising:

micro transfer printing one or more printable substructures of the printable structures.

13. The method of claim 1, wherein said micro transfer printing comprises:

contacting one or more printable structures of the printable structures with a conformable transfer device having a contact surface, wherein contact between the contact surface and the one or more printable structures adheres the one or more printable structures to the contact surface;

contacting the one or more printable structures disposed on the contact surface with the receiving surface of a destination substrate; and

separating the contact surface of the conformable transfer device and the one or more printable structures, wherein the one or more printable structures are transferred onto the receiving surface, thereby assembling the one or more printable structures on the receiving surface of the destination substrate.

14. The method of claim 13, wherein the conformable transfer device is an elastomer stamp.

15. A method of preparing printable materials for micro assembly from a native device substrate using an intermediate substrate having a controlled tackiness, the method comprising:

depositing one or more materials on the native device substrate , thereby forming an epitaxial material;

forming devices with the epitaxial material on the substrate;

delineating releasable structures comprising the devices in the epitaxial material, thereby partially exposing the device substrate;

forming anchoring structures and tethering structures such that the releasable structures are connected to the substrate by the anchoring structures and tethering structures following contact of the substrate with the etchant;

temporarily bonding the epitaxial material to the intermediate substrate and performing a laser-lift off process, thereby separating the epitaxial material from the device substrate and thereby inverting the epitaxial material for micro assembly, wherein;

the controlled tackiness of the intermediate substrate is configured so that a transfer element can remove the materials from the intermediate substrate for micro assembly, and

the native substrate is transparent to laser illumination that is absorbed strongly by an absorbing layer on the native substrate so that upon exposure to the laser illumination the absorbing layer at least partially decomposes or otherwise forms an interface that can initiate separation between the native substrate and the devices for micro assembly;

at least partially completing the formation or delineation of devices on the intermediate substrate;

forming anchoring, tethering, or encapsulation structures insoluble to an etchant for releasing the epitaxial material from the intermediate substrate;

releasing the devices from the intermediate substrate by removal of at least a portion of the selectively removable layer positioned between at least a portion of the intermediate substrate and at least a portion of the devices, thereby forming printable micro assemble-able devices from the native substrate via the intermediate substrate; and

transferring the released materials for micro assembly on the intermediate substrate to a second intermediate stamp, thereby presenting the epitaxial material for micro assembly in a different un-inverted configuration, the second intermediate stamp also having controlled tackiness such that the second intermediate stamp can remove the materials for micro assembly from the intermediate stamp and a transfer element can remove the epitaxial material for micro assembly from the second intermediate stamp.

16. The method of claim 15, wherein the device substrate comprises a member selected from the group consisting of sapphire, gallium arsenide, indium phosphide, and silicon on insulator.

17. The method of claim 15 or 16, wherein the one or more materials deposited on the device substrate comprise at least one member selected from the group consisting of GaN, AlGaN, and SiN.

18-33. -33. (canceled)

34. A method of preparing released materials for micro assembly from a native sapphire substrate via an intermediate substrate, the method comprising:

preparing materials for micro assembly by epitaxial growth on the native sapphire substrate to form an epitaxial material;

forming at least one of anchoring, tethering, and encapsulation structures insoluble to an etchant for releasing the materials for micro assembly from the intermediate substrate;

adhering the materials for micro assembly to an intermediate substrate to form a bonded pair of substrates;

performing a laser-lift off process, thereby separating the materials for micro assembly from the native sapphire substrate and separating the bonded pair of substrates, wherein;

the materials for micro assembly are thereby inverted, and

the sapphire substrate is transparent to laser illumination that is absorbed strongly by an absorbing layer on the sapphire substrate such that upon exposure to the laser illumination the absorbing layer at least partially decomposes or otherwise forms an interface that can initiate separation between the sapphire substrate and the materials for micro assembly; and

releasing the materials for micro assembly from the intermediate substrate by removing at least a portion of a selectively removable layer positioned between at least a portion of the intermediate substrate and at least a portion of the materials for micro assembly with the releasing etchant, thereby removing the selectively removable layer underneath the releasable structures and forming released, micro assemble-able GaN materials or devices from sapphire native substrates via the intermediate substrate.

35. The method of claim 34, comprising:

transferring the released materials for micro assembly on the intermediate substrate to an intermediate stamp, thereby presenting the materials for micro assembly in a different, un-inverted configuration for micro assembly.

46. The method of claim 34, wherein forming the selectively removable layer is done prior to adhering the materials.

36-45. -45. (canceled)