# US 2020/0402964 A1 · Multi-junction led with eutectic bonding and method of manufacturing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0402964 A1 - Document ID: US20200402964A1 - Status: Published application - Kind: A1 - Application number: 16/578,258 - Filed: 2019-09-20 - Published: 2020-12-24 - Earliest claimed: 2019-06-24 - Assignees: Sundiode Korea - Applicants: Sundiode Korea - Inventors: James Chinmo KIM - Web page: https://patentgrep.com/patent/US20200402964A1 ## CPC - H10W 90/00: Package configurations - C22C 5/02: Alloys based on gold - H10H 20/812: within the light-emitting regions, e.g. having quantum confinement structures - H10H 20/816: having carrier transport control structures, e.g. highly-doped semiconductor layers or current-blocking structures - H10H 20/821: of the light-emitting regions, e.g. non-planar junctions - H10H 20/835: {Reflective materials} - H10H 20/84: Coatings, e.g. passivation layers or antireflective coatings - H10H 20/857: Interconnections, e.g. lead-frames, bond wires or solder balls - H10H 20/032: {of electrodes} - H10H 20/034: {of coatings} - H10H 20/0364: {of interconnections} - H10H 20/831: characterised by their shape - H10H 20/8312: {extending at least partially through the bodies} - H10W 72/07236: {Soldering or alloying} - H10W 72/07336: {Soldering or alloying} - H10W 72/07355: {changes in materials} - H10W 72/3524: {Eutectic alloys} - H10W 72/922: {Bond pads being integral with underlying chip-level interconnections} - H10W 72/926: {Multiple bond pads having different sizes} - H10W 72/932: {Plan-view shape, i.e. in top view} - H10W 72/936: {Multiple bond pads having different shapes} - H10W 72/9415: {relative to the surface, e.g. recessed, protruding} - H10W 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu} - H10W 72/957: {Multiple bond pads having different materials} - H10W 90/732: {between stacked chips} - H10W 90/792: {between multiple chips} - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 - C22C: ALLOYS (treatment of alloys C21D, C22F) - H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS ## Abstract Disclosed are multi-junction light emitting diode (LED) formed by using eutectic bonding and method of manufacturing the multi-junction LED. The multi-junction LED is formed by stacking a separately formed light emitting structure on another light emitting structure by using eutectic bonding. Since separately grown light emitting structure is stacked on the light emitting structure using the eutectic metal alloy bonding, it is possible to prevent crystal defects occurring between the light emitting structures when sequentially grown. Further, since the eutectic metal alloy can be formed in various patterns, it is possible to control and optimize adhesive strength, transmittance of the light generated in the upper light emitting structure, and resistance. ## Claims ### Claim 1 A multi-junction LED using eutectic bonding comprising: a first light emitting structure formed on a substrate; a second light emitting structure formed on the first light emitting structure; a common current spreading layer formed between the first light emitting structure and the second light emitting structure; an insulating layer formed on the second light emitting structure; a third light emitting structure formed on the insulating layer; and a metal bonding layer formed between the third light emitting structure and the insulating layer to bond the third light emitting structure to the insulating layer by using eutectic bonding. ### Claim 2 (depends on 1) The multi-junction LED of claim 1, wherein the metal bonding layer has a eutectic metal alloy. ### Claim 3 (depends on 2) The multi-junction LED of claim 2, wherein the eutectic metal alloy has Au—Ge alloy or Au—Sn alloy. ### Claim 4 (depends on 3) The multi-junction LED of claim 3, wherein the Au in the Au—Ge alloy has a weight ratio ranging from 65 wt % to 80 wt %. ### Claim 5 (depends on 3) The multi-junction LED of claim 3, wherein the Au in the Au—Sn alloy has weight ratio ranging from 70 wt % to 90 wt %. ### Claim 6 (depends on 1) The multi-junction LED of claim 1, wherein the metal bonding layer is formed on the insulating layer and has a shape in which one end and the other end of a line forming a rectangle are close to or in contact with each other. ### Claim 7 (depends on 6) The multi-junction LED of claim 6, wherein the interior of the rectangle shape of the metal bonding layer is hollow. ### Claim 8 (depends on 6) The multi-junction LED of claim 6, wherein the interior of the rectangle shape of the metal bonding layer is filled with a lattice pattern. ### Claim 9 (depends on 6) The multi-junction LED of claim 6, wherein the interior of the rectangle shape of the metal bonding layer is filled with isolated dots spaced apart from each other. ### Claim 10 (depends on 1) The multi-junction LED of claim 1, further comprising: a first tunnel junction layer formed between the common current spreading layer and the first light emitting layer; and a second tunnel junction layer formed between the common current spreading layer and the second light emitting layer. ### Claim 11 (depends on 1) The multi-junction LED of claim 1, wherein the first light emitting structure has a first n-type semiconductor layer, a first active layer and a first p-type semiconductor layer that are sequentially deposited, wherein the second light emitting structure has a second p-type semiconductor layer, a second active layer and a second n-type semiconductor layer that are sequentially deposited, wherein the third light emitting structure has a third p-type semiconductor layer, a third active layer and a third n-type semiconductor layer that are sequentially deposited. ### Claim 12 (depends on 11) The multi-junction LED of claim 11, wherein the LED has a first mesa structure in which upper layers of the first n-type semiconductor layer are removed to expose a part of an upper surface of the first n-type semiconductor layer, and a second structure in which upper layers of the common current spreading layer are removed to expose a part of an upper surface of the common current spreading layer. ### Claim 13 (depends on 12) The multi-junction LED of claim 12, wherein a first negative electrode is formed on an upper surface of the first n-type semiconductor layer exposed by the first mesa structure, a first positive electrode is formed on an upper surface of the common current spreading layer exposed by the second mesa structure, a second negative electrode is formed on the second n-type semiconductor layer, a third negative electrode is formed on the third n-type semiconductor layer, and a second positive electrode is formed on the insulating layer and electrically connected to the metal bonding layer. ### Claim 14 (depends on 13) The multi-junction LED of claim 13, wherein the second positive electrode is of the same material as the metal bonding layer. ### Claim 15 (depends on 13) The multi-junction LED of claim 13, further comprising: a conductive layer for electrically connecting the first positive electrode and the second positive electrode. ### Claim 16 (depends on 13) The multi-junction LED of claim 13, wherein the first negative electrode, the first positive electrode, the second negative electrode, and the second positive electrode are formed at edges of the LED, respectively. ### Claim 17 (depends on 11) The multi-junction LED of claim 11, wherein a first negative electrode is formed on the third light emitting structure and extended to the first n-type semiconductor layer, a first positive electrode is formed on the third light emitting structure and extended to the common current spreading layer, a second negative electrode is formed on the third light emitting structure and extended to the second n-type semiconductor layer, a third negative electrode is formed on the third light emitting structure, and a second positive electrode is formed on the third light emitting structure and extended to the third p-type semiconductor layer. ### Claim 18 (depends on 17) The multi-junction LED of claim 17, further comprising: a conductive layer formed on the third light emitting structure and electrically connecting the first positive electrode and the second positive electrode. ### Claim 19 (depends on 1) The multi-junction LED of claim 1, wherein the first light emitting structure emits blue light, the second light emitting structure emits green light, and third light emitting structure emits red light. ### Claim 20 A method of manufacturing a multi-junction LED using eutectic bonding comprising: forming a first light emitting structure having a first n-type semiconductor layer, a first active layer and a first p-type semiconductor layer on a substrate; sequentially forming a first tunnel junction layer, a common current spreading layer, and a second tunnel junction layer on the first light emitting structure; forming a second light emitting structure having a second p-type semiconductor layer, a second active layer, and a second n-type semiconductor layer on the second tunnel junction layer; forming an insulating layer on the second light emitting structure; forming a metal bonding layer on the insulating layer; and stacking a third light emitting structure formed of a third p-type semiconductor layer, a third active layer, and a third n-type semiconductor layer on the metal bonding layer by using eutectic bonding. ### Claim 21 (depends on 20) The method of claim 20, wherein before forming the insulating layer, the method comprises: forming a first mesa structure for removing upper layers of the first n-type semiconductor layer such that a part of an upper surface of the first n-type semiconductor layer is exposed; and forming a second mesa structure to remove upper layers of the common current spreading layer so that a part of an upper surface of the common current spreading layer is exposed. ### Claim 22 (depends on 21) The method of claim 21, wherein after forming the insulating layer, the method comprises: forming a first negative electrode on an upper surface of the first n-type semiconductor layer exposed by the first mesa structure; forming a first positive electrode on an upper surface of the common current spreading layer exposed by the second mesa structure; forming a second negative electrode on the second n-type semiconductor layer; forming a third negative electrode on the third n-type semiconductor layer; forming a second positive electrode on the insulating layer, the second positive electrode being electrically connected to the metal bonding layer; and forming a conductive layer that electrically connects the first positive electrode and the second positive electrode. ### Claim 23 (depends on 20) The method of claim 20, wherein after stacking a third light emitting structure, the method comprises: forming a first contact hole extending from the upper surface of the third light emitting structure to the first n-type semiconductor layer; forming a second contact hole extending from an upper surface of the third light emitting structure to the common current spreading layer; forming a third contact hole extending from the upper surface of the third light emitting structure to the third p-type semiconductor layer; and forming a fourth contact hole extending from the upper surface of the third light emitting structure to the second n-type semiconductor layer. ### Claim 24 (depends on 23) The method of claim 23, wherein the method comprises forming insulating films on the inner side surfaces of the first contact hole, the second contact hole, the third contact hole, and the fourth contact hole, respectively. ### Claim 25 (depends on 24) The method of claim 24, wherein after forming the insulating film, the method comprises: forming a first negative electrode in the first contact hole, a first positive electrode in the second contact hole, a second positive electrode in the third contact hole, and a second negative electrode in the fourth contact hole; forming a third negative electrode on the third light emitting structure; and forming a conductive layer on the third light emitting structure electrically connecting the first positive electrode and the second positive electrode to each other.