LED unit, image display element, and method of manufacturing the same
An N electrode and a P electrode formed on the same surface are respectively bonded to a cathode electrode and an anode electrode of a drive circuit board through a connection step performed once. An LED unit includes a first wiring ( 21 ) that is disposed inside a groove formed in a nitride semiconductor ( 13 ) to penetrate between an N-type layer ( 10 ) and a P-type layer ( 12 ) and is electrically connected to the N-type layer ( 10 ), and a second wiring that includes a P electrode ( 30 ) connected to the P-type layer ( 12 ) and an N electrode ( 31 ) connected to the first wiring ( 21 ), in which the N electrode ( 31 ) and the P electrode ( 30 ) are formed on the same surface.
1. An LED unit comprising:
a plurality of micro-LED chips each having a nitride semiconductor in which an N-type layer, a light emitting layer, and a P-type layer are laminated in this order in a pixel region and further having a P electrode, the plurality of micro-LED chips sharing an N electrode, and the LED unit having a common connection region in which the N electrode is disposed;
first wiring that is disposed inside a groove formed in the nitride semiconductor to penetrate between the N-type layer and the P-type layer and is electrically connected to the N-type layer; and
second wiring that forms a P electrode connected to the P-type layer and an N electrode connected to the first wiring,
wherein:
the N electrode and the P electrode are formed on a same surface;
a surface of the first wiring that is at a side of the same surface on which the N electrode and the P electrode are formed is covered with an insulating layer; and
the first wiring and the N electrode are connected to each other only in the common connection region.
2. The LED unit according to claim 1 , wherein:
a division region used to sever the LED unit from another LED unit is provided in an outer periphery of the LED unit;
a unit separation groove used to separate the LED unit from another LED unit is formed in the division region;
the unit separation groove is separated from the groove in which the first wiring is disposed and has a width of 10 μm or more and 30 μm or less; and
wherein the first wiring is not present inside the unit separation groove.
3. The LED unit according to claim 2 , wherein the first wiring and the second wiring are not present in the division region.
4. The LED unit according to claim 2 , wherein:
the common connection region is provided around the pixel region; and
the N electrode covers the P-type layer and the groove in the common connection region.
5. The LED unit according to claim 4 , wherein:
the N electrode is divided along four sides of the pixel region having a substantially rectangular shape; and
a length of the N electrode in a side direction is larger than a length corresponding to at least two micro-LED chips.
6. The LED unit according to claim 1 , wherein the N electrode is disposed in a common connection region provided inside the pixel region, and one N electrode is shared by four micro-LED chips and is disposed at an equal distance from the four micro-LED chips.
7. The LED unit according to claim 1 ,
wherein the first wiring reaches up to a light emitting surface of the micro-LED chip, and
wherein the first wiring and the N-type layer are in electrical contact with each other at a sidewall of the groove.
8. The LED unit according to claim 1 , wherein:
an inclined portion of the micro-LED chip along a light emission direction around the light emitting layer is inclined from 35 degrees to 55 degrees with respect to a plane along an extension direction of the light emitting layer; and
a side surface of the groove on which the first wiring is formed is inclined at an angle greater than 70 degrees.
9. The LED unit according to claim 8 , wherein the first wiring penetrates a transparent insulating film covering the inclined portion.
10. The LED unit according to claim 8 , wherein the inclined portion is covered with a transparent insulating film, and the first wiring covers an outside of the transparent insulating film.
11. The LED unit according to claim 8 , wherein an insulating film is formed between the first wiring formed inside the groove and the N-type layer.
12. The LED unit according to claim 8 , wherein the first wiring formed inside the groove is in direct contact with the N-type layer.
13. The LED unit according to claim 8 , wherein a metal electrode is arranged in contact with a surface of the P-type layer.
14. The LED unit according to claim 8 , wherein the first wiring extends to a light emitting surface of each of the plurality of micro-LED chips.
15. The LED unit according to claim 1 , wherein the first wiring is disposed to surround a perimeter of the plurality of micro-LED chips.
16. An image display element comprising a drive circuit board provided with a circuit which supplies a current causing each of a plurality of micro-LED chips to emit light; and
the LED unit according to claim 1 stacked on the drive circuit board,
wherein:
an anode electrode on the drive circuit board is connected to the P electrode; and
a cathode electrode on the drive circuit board is connected to the N electrode.
17. The LED unit according to claim 1 , wherein:
the first wiring is entirely covered by the insulating layer; and
a length of the N electrode is larger than a width of the groove.
18. The LED unit according to claim 1 , wherein a side surface of the groove is inclined at an angle greater than 70 degrees with respect to a plane along an extending direction of the light emitting layer;
the side surface is covered with an insulating film; and
the first wiring covers an outside of the insulating film.
19. The LED unit according to claim 18 , wherein a metal electrode is disposed on a surface of the P-type layer.
20. The LED unit according to claim 18 , wherein the first wiring extends a light emitting surface of each of the plurality of micro-LED chips.