Light-emitting diode and its manufacturing method

• US 20020117676A1
• Filed: 02/26/2002
• Published: 08/29/2002
• Est. Priority Date: 02/26/2001
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Katoh, Masaaki
• Granted Patent: US 7,126,163 B2
• Time in Patent Office: Days
• US Class Current: 257/91
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• 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 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/486 adapted for surface mounting

Abstract

The present invention provides a surface-mounted LED that is easy to be made thin and having high reliability, as well as provides its manufacturing method.

Specifically, the present invention provides a light-emitting diode having a light-emitting diode chip mounted on a surface of a printed substrate, this light-emitting diode chip comprising a substrate; a semiconductor layer laminated on the substrate and comprising an N-type semiconductor layer and a P-type semiconductor layer, wherein its PN junction surface is perpendicular to the surface of the printed substrate and a portion in the vicinity of the PN junction surface is rendered to be a light-emitting portion; a pair of electrodes that applies voltage to the semiconductor layer; and a light reflecting layer formed on the front surface or back surface of the light-emitting chip or in the chip so as to be approximately parallel to the PN junction surface, this light reflecting layer reflecting light emitted from the light-emitting portion.

Claims

1. A light-emitting diode comprising a light-emitting diode chip mounted on a surface of a printed substrate, the light-emitting diode chip including:

a substrate;

a semiconductor layer laminated on the substrate and formed of an N-type semiconductor layer and a P-type semiconductor layer, wherein its PN junction surface is perpendicular to the surface of the printed substrate and a portion in the vicinity of the PN junction surface is rendered to be a light-emitting portion;

a pair of electrodes for applying voltage to the semiconductor layer; and

a light reflecting layer for reflecting light emitted from the light-emitting portion,

wherein the light reflecting layer is formed on a front surface or a back surface of the light-emitting diode chip or in the light-emitting diode chip and is approximately parallel to the PN junction surface.

2. A light-emitting diode claimed in claim 1, wherein the substrate is made of a transparent substrate and the light reflecting layer is formed on the front surface or back surface of the transparent substrate or on the surface of the semiconductor layer.

3. A light-emitting diode claimed in claim 2, wherein the light reflecting layer comprises a DBR diffraction grating structure formed on the surface of the transparent substrate.

4. A light-emitting diode claimed in claim 1 or 2, wherein the light reflecting layer is formed of a metal thin film.

5. A light-emitting diode claimed in claim 4, wherein the metal thin film is formed directly or via a dielectric thin film on the back surface of the transparent substrate.

6. A light-emitting diode claimed in claim 4 or 5, wherein the metal thin film is formed of an Ni vapor-deposition film.

7. A light-emitting diode claimed in claim 5, wherein the dielectric thin film is formed of an SiO₂ film or an Al₂O₃ film, and the metal thin film is formed of an AuBe vapor-deposition film or an Au vapor-deposition film.

8. A light-emitting diode claimed in any one of claims 1 to 7, wherein the Ni vapor-deposition film has a thickness of 100 nm or more.

9. A light-emitting diode claimed in claim 7, wherein the SiO₂ film or the Al₂O₃ film has a thickness of approximately 3 to 60 nm, and the AuBe vapor-deposition film or the Au vapor-deposition film has a thickness of approximately 3 to 60 nm

10. A light-emitting diode claimed in any one of claims 1 to 9, wherein the substrate is formed of a transparent substrate transparent to color emitted by the light-emitting diode chip.

11. A method for manufacturing a light-emitting diode comprising mounting, on a surface of a printed substrate, a light-emitting diode chip having a substrate, a semiconductor layer which is laminated on a surface of the substrate, is formed of an N-type semiconductor layer and a P-type semiconductor layer and has a light-emitting portion in the vicinity of a PN junction surface between the N-type and P-type semiconductor layers, a pair of electrodes for applying voltage to the semiconductor layer, and a light reflection layer reflecting light emitted from the light-emitting portion, thereby obtaining the light-emitting diode, the method comprising, for mounting the light-emitting diode chip on the printed substrate,

the step of forming beforehand the light reflecting layer on a front surface or a back surface of the substrate of the light-emitting diode chip or in the light-emitting diode chip in such a manner that the light reflecting layer is approximately parallel to the PN junction surface, and

the step of fixing the obtained light-emitting diode chip on the printed substrate so that the PN junction surface is perpendicular to the surface of the spring substrate and electrically connecting the pair of electrodes of the light-emitting diode chip to the printed substrate.