Direct-Bonded LED Arrays and Applications

• US 20190088633A1
• Filed: 03/13/2018
• Published: 03/21/2019
• Est. Priority Date: 03/16/2017
• Status: Active Grant

• Current Assignee: Adeia Semiconductor Technologies LLC (Adeia Inc.)
• Original Assignee: Invensas Corporation
• Inventors: Tao, Min, Wang, Liang, Katkar, Rajesh, Uzoh, Cyprian Emeka
• Granted Patent: US 10,629,577 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 21/02118 carbon based polymeric organic or inorganic material, e.g. polyimides, poly cyclobutene or PVC polymers per se C08G, photoresist per se G03F
• CPC Class Codes: H01L 21/3212 by chemical mechanical polishing [CMP]
• CPC Class Codes: H01L 2224/08137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/08145 the bodies being stacked
• CPC Class Codes: H01L 2224/80013 Plasma cleaning
• CPC Class Codes: H01L 2224/80355 having an external coating, e.g. protective bond-through coating
• CPC Class Codes: H01L 2224/80357 being flush with the surface
• CPC Class Codes: H01L 24/08 of an individual bonding area
• CPC Class Codes: H01L 24/80 Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
• CPC Class Codes: H01L 25/105 the devices being of a type provided for in group H01L27/00
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 25/18 the devices being of types provided for in two or more different subgroups of the same main group of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0025 relating to coatings
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• 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 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/32 : containing nitrogen
• CPC Class Codes: H01L 33/44 : characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 : Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

Direct-bonded LED arrays and applications are provided. An example process fabricates a LED structure that includes coplanar electrical contacts for p-type and n-type semiconductors of the LED structure on a flat bonding interface surface of the LED structure. The coplanar electrical contacts of the flat bonding interface surface are direct-bonded to electrical contacts of a driver circuit for the LED structure. In a wafer-level process, micro-LED structures are fabricated on a first wafer, including coplanar electrical contacts for p-type and n-type semiconductors of the LED structures on the flat bonding interface surfaces of the wafer. At least the coplanar electrical contacts of the flat bonding interface are direct-bonded to electrical contacts of CMOS driver circuits on a second wafer. The process provides a transparent and flexible micro-LED array display, with each micro-LED structure having an illumination area approximately the size of a pixel or a smallest controllable element of an image represented on a high-resolution video display.

Claims

1. An apparatus, comprising:

a direct-bonded light emitting diode (LED) array; and

a flat bonding interface of at least one LED element in the direct-bonded LED array, each flat bonding interface comprising at least first and second coplanar conductive areas comprising electrical contacts of each LED element.

2. The apparatus of claim 1, wherein each first coplanar conductive area in each flat bonding interface comprises an electrical contact to an n-type layer of a group III-V semiconductor of each LED element;

and

wherein each second coplanar conductive area in each flat bonding interface comprises an electrical contact to a p-type layer of a group III-V semiconductor of each LED element.

3. The apparatus of claim 2, wherein the first coplanar conductive area comprises multiple conductive contacts to the n-type layer, and the second coplanar conductive area comprises multiple conductive contacts to the p-type layer.

4. The apparatus of claim 2, where in the first coplanar conductive area is electrically connected to the n-type layer at multiple locations, and the second coplanar conductive area is electrically connected to the p-type layer at multiple locations.

5. The apparatus of claim 2, further comprising a frame-traced dot array electrode as the coplanar electrical contact to n-type layer of the group III-V semiconductors of each LED element;

and

a circular or square dot array electrode as the coplanar electrical contact to p-type layer of the group III-V semiconductors of each LED element.

6. The apparatus of claim 1, further comprising at least a third coplanar conductive area electrically isolated from the first conductive area and the second conductive area, the third coplanar conductive area for thermal dissipation, for connecting to an electrical ground, or for conducting a signal.

7. The apparatus of claim 1, wherein each LED in the direct-bonded LED array comprises a micro-LED having an illumination area approximately a size of a pixel of a high-resolution video display, or an illumination area approximately a size of a smallest controllable element of an image represented on the high-resolution video display.

8. The apparatus of claim 1, further comprising at least a direct metal-to-metal contact bond between each first and second conductive area in each flat bonding interface of each LED element, and respective conductive contacts of driver circuitry for each LED element, the driver circuitry direct-bonded to each flat bonding interface of each LED element.

9. The apparatus of claim 8, further comprising a direct dielectric-to-dielectric contact bond between dielectric areas of each flat bonding interface of each LED element and respective dielectric areas of each flat bonding interface of each instance of the driver circuitry.

10. The apparatus of claim 9, wherein each direct dielectric-to-dielectric contact bond comprises at least one plasma-activated surface of the direct dielectric-to-dielectric contact bond.

11. The apparatus of claim 1, further comprising a flexible organic substrate of the direct-bonded LED array providing a flexible and transparent direct-bonded LED array display.

12. The apparatus of claim 1, further comprising a distributed Bragg reflector (DBR) located at a top of each LED element, at a bottom of each LED element, or integrated in the flat bonding interface of each LED element.

13. The apparatus of claim 1, further comprising an optical waveguide bonded to a top surface or a side surface of the direct-bonded LED array.

14. The apparatus of claim 1, further comprising a semiconductor element bonded to a top surface or a side surface of the direct-bonded LED array.

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25. An apparatus, comprising:

a direct-bonded light emitting diode (LED) array; and

a planarized interface of at least one LED element in the direct-bonded LED array, each planarized interface comprising at least first and second coplanar conductive areas comprising electrical contacts of each LED element.

26. The apparatus of claim 25, further comprising a direct dielectric-to-dielectric contact bond between dielectric areas of each planarized interface of each LED element and respective dielectric areas of each planarized interface of each instance of a driver circuitry.

27. The apparatus of claim 25, wherein each direct dielectric-to-dielectric contact bond comprises at least one plasma-activated surface of the direct dielectric-to-dielectric contact bond.