# US 12,009,465 B1 · LED array having transparent substrate with conductive layer for enhanced current spread > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,009,465 B1 - Document ID: US12009465B1 - Status: Granted - Kind: B1 - Application number: 17/681,203 - Filed: 2022-02-25 - Granted: 2024-06-11 - Earliest claimed: 2019-11-26 - Assignees: Meta Platforms Technologies, LLC - Applicants: Meta Platforms Technologies, LLC - Inventors: Christophe Antoine Hurni; John Michael Goward; Chloe Astrid Marie Fabien - Web page: https://patentgrep.com/patent/US12009465B1 ## CPC - H10H 20/833: Transparent materials - H10H 20/857: Interconnections, e.g. lead-frames, bond wires or solder balls - G02B 27/017: {Head mounted} - H10H 20/01: Manufacture or treatment - H10H 20/855: Optical field-shaping means, e.g. lenses - H10H 29/14: comprising multiple light-emitting semiconductor components - H10W 90/00: Package configurations - G02B 2027/0178: {Eyeglass type (eyeglass details G02C)} - H10H 20/0364: {of interconnections} - H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract In a flip-chip LED assembly having an array of LEDs formed on the same substrate, different LEDs of the array have different distances to the n-contacts of the assembly. This may cause current crowding as current has to spread from the n-contacts through the substrate to each the farthest LEDs of the LED array, requiring LEDs that are farther away to be driven with a higher voltage in order to receive a desired amount of current. To spread current more evenly through the LED assembly and reduce a voltage difference between the closest and farthest LEDs of the array, a current spreading layer having a conductive material (e.g., a conductive oxide) is formed on a surface of the substrate of the LED assembly. The current spreading layer may be a bulk layer or be patterned to increase light extraction from the LEDs of the array. ## Claims ### Claim 1 A light emitting diode (LED) assembly comprising: a substrate assembly comprising a first substrate of a first type, a layer of light emitting material, and a second substrate of a second type; one or more contacts of a first type formed on a first surface of or within the first substrate; an array of LEDs, wherein each LED of the array of LEDs corresponds to a respective contact of a second type formed on a first surface of the second substrate, the array of LEDs sharing the one or more contacts of the first type and configured to emit light when current is applied between the respective contacts of the second type and at least one of the one or more contacts of the first type; and a current spreading layer formed on a second surface of the first substrate opposite to the first surface of or within the first substrate, wherein the current spreading layer reduces a voltage difference between different LEDs of the array of LEDs during operation of the LED assembly, and wherein the current spreading layer is formed with a plurality of openings. ### Claim 2 (depends on 1) The LED assembly of claim 1, wherein: the first substrate of the first type is an n-type layer; the second substrate of the second type is a p-type layer; the one or more contacts of the first type are n-type contacts; and the respective contact of the second type is a p-type contact. ### Claim 3 (depends on 1) The LED assembly of claim 1, wherein LEDs of the array of LEDs are further defined by etching or partially etching through the second substrate, the layer of light emitting material, and partially through the first substrate. ### Claim 4 (depends on 1) The LED assembly of claim 1, wherein the current spreading layer is transparent or partially transparent. ### Claim 5 (depends on 1) The LED assembly of claim 1, wherein the current spreading layer comprises a conductive oxide material. ### Claim 6 (depends on 5) The LED assembly of claim 5, wherein the conductive oxide material comprises indium tin oxide (ITO). ### Claim 7 (depends on 1) The LED assembly of claim 1, further comprising an optically transmissive material disposed within the plurality of openings. ### Claim 8 (depends on 1) The LED assembly of claim 1, wherein the plurality of openings correspond to locations of LEDs of the array of LEDs. ### Claim 9 (depends on 1) The LED assembly of claim 1, wherein the current spreading layer has a resistivity of 0.001 Ohm cm or less. ### Claim 10 (depends on 1) The LED assembly of claim 1, wherein the current spreading layer has a thickness of 50 nm or more. ### Claim 11 A light emitting diode (LED) assembly comprising: a substrate assembly comprising a first substrate of a first type, a layer of light emitting material, and a second substrate of a second type; one or more contacts of a first type formed on a first surface of or within the first substrate; an array of LEDs, wherein each LED of the array of LEDs corresponds to a respective contact of a second type formed on a first surface of the second substrate, the array of LEDs sharing the one or more contacts of the first type and configured to emit light when current is applied between the respective contacts of the second type and at least one of the one or more contacts of the first type; and a current spreading layer formed on a second surface of the first substrate opposite to the first surface of or within the first substrate, wherein the current spreading layer reduces a voltage difference between different LEDs of the array of LEDs during operation of the LED assembly, and wherein the current spreading layer is formed within one or more trenches formed on the second surface of the first substrate. ### Claim 12 (depends on 11) The LED assembly of claim 11, wherein: the first substrate of the first type is an n-type layer; the second substrate of the second type is a p-type layer; the one or more contacts of the first type are n-type contacts; and the respective contact of the second type is a p-type contact. ### Claim 13 (depends on 11) The LED assembly of claim 11, wherein LEDs of the array of LEDs are further defined by etching or partially etching through the second substrate, the layer of light emitting material, and partially through the first substrate. ### Claim 14 (depends on 11) The LED assembly of claim 11, wherein the current spreading layer is transparent or partially transparent. ### Claim 15 (depends on 11) The LED assembly of claim 11, wherein the current spreading layer comprises a conductive oxide material. ### Claim 16 (depends on 15) The LED assembly of claim 15, wherein the conductive oxide material comprises indium tin oxide (ITO). ### Claim 17 (depends on 11) The LED assembly of claim 11, wherein the one or more trenches are formed at locations on the second surface of the first substrate corresponding to spaces between adjacent LEDs of the array of LEDs. ### Claim 18 (depends on 11) The LED assembly of claim 11, wherein the current spreading layer has a resistivity of 0.001 Ohm cm or less. ### Claim 19 (depends on 11) The LED assembly of claim 11, wherein the current spreading layer has a thickness of 50 nm or more. ### Claim 20 A light emitting diode (LED) assembly comprising: a substrate assembly comprising a first substrate of a first type, a layer of light emitting material, and a second substrate of a second type; one or more contacts of a first type formed on a first surface of or within the first substrate; an array of LEDs, wherein each LED of the array of LEDs corresponds to a respective contact of a second type formed on a first surface of the second substrate, the array of LEDs sharing the one or more contacts of the first type and configured to emit light when current is applied between the respective contacts of the second type and at least one of the one or more contacts of the first type; and a current spreading layer formed on a second surface of the first substrate opposite to the first surface of or within the first substrate, wherein the current spreading layer reduces a voltage difference between different LEDs of the array of LEDs during operation of the LED assembly, and wherein the current spreading layer comprises a first portion formed on the second surface of the first substrate, and a second portion formed within one or more trenches formed on the second surface of the first substrate.