INTEGRATED SEMICONDUCTOR LIGHT-EMITTING DEVICE AND ITS MANUFACTURING METHOD

• US 20100320488A1
• Filed: 04/30/2007
• Published: 12/23/2010
• Est. Priority Date: 05/01/2006
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Horie, Hideyoshi
• Granted Patent: US 8,581,274 B2
• Time in Patent Office: Days
• US Class Current: 257/91
• CPC Class Codes: H01L 2224/05567 the external layer being at least partially embedded in the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05639 Silver [Ag] as principal constituent
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05666 Titanium [Ti] as principal constituent
• CPC Class Codes: H01L 2224/14 of a plurality of bump connectors
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• 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

Abstract

An integrated compound semiconductor light-emitting-device capable of emitting light as a large-area plane light source. The light-emitting-device includes plural light-emitting-units formed over a substrate, the light-emitting-units having a compound semiconductor thin-film crystal layer, first and second-conductivity-type-side electrodes, a main light-extraction direction is the side of the substrate, and the first and the second-conductivity-type-side electrodes are formed on the opposite side to the light-extraction direction. The light-emitting-units are electrically separated from each other by a light-emitting-unit separation-trench. An optical coupling layer is formed between the substrate and the first-conductivity-type semiconductor layer. The optical coupling layer is common to the plurality of light-emitting-units, and capable of optical coupling of the plurality of light-emitting-units and distributing a light to the entire light-emitting-device.

Claims

1-70. -70. (canceled)

71. :

An integrated compound semiconductor light-emitting-device, comprising;

a substrate transparent to an emission wavelength; and

a plurality of light-emitting-units formed on the substrate, wherein

the light-emitting-unit comprises a compound semiconductor thin-film crystal layer including a first-conductivity-type semiconductor layer containing a first-conductivity-type cladding layer, an active layer structure, and a second-conductivity-type semiconductor layer containing a second-conductivity-type cladding layer;

a second-conductivity-type-side electrode; and

a first-conductivity-type-side electrode on the substrate;

a main light-extraction direction is the side of the substrate, and the first-conductivity-type-side electrode and the second-conductivity-type-side electrode are formed on the opposite side to the main light-extraction direction;

the light-emitting-units are electrically separated from each other by a light-emitting-unit separation-trench formed between adjacent light-emitting-units; and

the light-emitting-unit comprises;

(a) single light-emitting-point comprising the active layer structure, the second-conductivity-type semiconductor layer and the second-conductivity-type-side electrode; and

the first-conductivity-type-side electrode, or

(b) a plurality of light-emitting-points comprising the active layer structure, the second-conductivity-type semiconductor layer and the second-conductivity-type-side electrode; and

at least one first-conductivity-type-side electrode;

wherein the first-conductivity-type semiconductor layer provides electrical connection in the single light-emitting-unit; and

the light-emitting-device comprises an optical coupling layer formed between the substrate and the first-conductivity-type semiconductor layer;

the optical coupling layer being common to the plurality of light-emitting-units, and capable of optical coupling of the plurality of light-emitting-units and distributing a light emitted from one light-emitting-unit to the other light-emitting-units.

73. :

The light-emitting-device according to claim 71, wherein the optical coupling layer is a layer formed between the substrate and the first-conductivity-type cladding layer as a part of the thin-film crystal layer so as to be common to the plurality of light-emitting-units.

74. :

The light-emitting-device according to claim 71, wherein an average refractive index of the substrate is n_sb, an average refractive index of the optical coupling layer is n_oc, and an average refractive index of the first-conductivity-type semiconductor layer is n₁, each at an emission wavelength, and the relation;

n_sb<

n_oc and n₁<

n_oc

is satisfied.

75. :

The light-emitting-device according to claim 71, wherein an emission wavelength of the light-emitting-device is λ

(nm), an average refractive index of the substrate is n_sb, and an average refractive index of the optical coupling layer is n_oc, each at an emission wavelength, and a physical thickness of the optical coupling layer is t_oc (nm) and where a relative refractive index difference Δ

<sub>(oc−

sb)</sub> between the optical coupling layer and the substrate is defined as;

Δ

<sub>(oc−

sb)</sub>≡

((n_oc)²−

(n_sb)²)/(2×

(n_oc)²),

and t_oc is selected such that the relation;

(√

{square root over ( )}(2×

Δ

<sub>(oc−

sb)</sub>)×

n_oc×

π

×

t_oc)/λ

≧

π

/2

is satisfied.

76. :

The light-emitting-device according to claim 71, wherein an emission wavelength of the light-emitting-device is λ

(nm), an average refractive index of the optical coupling layer is n_oc, and an average refractive index of the first-conductivity-type semiconductor layer is n₁, each at an emission wavelength, and a physical thickness of the optical coupling layer is t_oc (nm) and a relative refractive index difference Δ

<sub>(oc−

1)</sub> between the optical coupling layer and the first-conductivity-type semiconductor layer is defined as

Δ

<sub>(oc−

1)</sub>≡

((n_oc)²−

(n₁)²)/(2×

(n_oc)²),

and t_oc is selected such that the relation;

(√

{square root over ( )}(2×

Δ

<sub>(oc−

1)</sub>)×

n_oc×

π

×

t_oc)/λ

≧

π

/2

is satisfied.

77. :

The light-emitting-device according to claim 71 or 72, wherein an overall specific resistance of the optical coupling layer ρ

_oc(Ω

·

cm) satisfies the relation;

0.5≦

ρ

_oc.

78. :

The light-emitting-device according to claim 71 or 72, wherein the optical coupling layer has a stacked structure of multiple layers.

79. :

The light-emitting-device according to claim 71 or 72, wherein the plurality of light-emitting-units are formed by forming the light-emitting-unit separation-trench by removing the thin-film crystal layer from the surface to the boundary of the optical coupling layer or to an inside portion of the optical coupling layer between the adjacent light-emitting-units.

80. :

The light-emitting-device according to claim 71 or 72, wherein the light-emitting-device has been divided from a light-emitting-device separation-trench formed between a plurality of light-emitting-devices;

wherein the light-emitting-device separation-trench is formed;

(i) to the intermediate portion of the optical coupling layer,

(ii) to the intermediate portion of the buffer layer,

(iii) so as to reach the substrate or a substrate used in the manufacturing process of the light-emitting-device, or

(iv) so as to remove a portion of the substrate or a substrate used in the manufacturing process of the light-emitting-device.

81. :

The light-emitting-device according to claim 71 or 72, comprising an insulating layer which is;

covering a bottom surface and a sidewall in the light-emitting-unit separation-trench,

covering at least a sidewall surface of the first-conductivity-type semiconductor layer, the active layer structure and the second-conductivity-type semiconductor layer among layers exposed as sidewall surface of the light-emitting-device,

in contact with a part of the first-conductivity-type-side electrode at the side of the main light-extraction direction, and

covering a part of the second-conductivity-type-side electrode on the side opposite to the main light-extraction direction.

82. :

The light-emitting-device according to claim 71, wherein the substrate is selected from the group consisting of sapphire, SiC, GaN, LiGaO₂, ZnO, ScAlMgO₄, NdGaO₃, and MgO.

83. :

The light-emitting-device according to claim 81, wherein R2 is a reflectance of reflection by the optical coupling layer, of a light having an emission wavelength of the light-emitting-device vertically incoming from the first-conductivity-type semiconductor layer side to the optical coupling layer, R12 is a reflectance of reflection by the insulating layer, of a light having an emission wavelength of the light-emitting-device vertically incoming from the second-conductivity-type semiconductor layer side to the insulating layer, R11 is a reflectance of reflection by the insulating layer, of a light having an emission wavelength of the light-emitting-device vertically incoming from the first-conductivity-type semiconductor layer side to the insulating layer, and R1q is a reflectance of reflection by the insulating layer, of a light having an emission wavelength of the light-emitting-device vertically incoming from the active layer structure side to the insulating layer, and the insulating layer is configured such that all of the conditions;

R2<

R12 

 

(Relation

     1)

R2<

R11 

 

(Relation

     2)

R2<

R1q 

 

(Relation

     3)

are satisfied.

72. :

An integrated compound semiconductor light-emitting-device, comprising;

a plurality of light-emitting-units, wherein

the light-emitting-unit comprises a compound semiconductor thin-film crystal layer including a first-conductivity-type semiconductor layer containing a first-conductivity-type cladding layer, an active layer structure and a second-conductivity-type semiconductor layer containing a second-conductivity-type cladding layer;

a second-conductivity-type-side electrode; and

a first-conductivity-type-side electrode;

a main light-extraction direction is the side of the first-conductivity-type semiconductor layer in relation to the active layer structure, and the first-conductivity-type-side electrode and the second-conductivity-type-side electrode are formed on the opposite side to the main light-extraction direction;

the light-emitting-units are electrically separated from each other by a light-emitting-unit separation-trench formed between adjacent light-emitting-units; and

the light-emitting-unit comprises;

(a) a single light-emitting-point comprising the active structure layer, the second-conductivity-type semiconductor layer and the second-conductivity-type-side electrode; and

the first-conductivity-type-side electrode, or

(b) a plurality of light-emitting-points comprising the active layer structure, the second-conductivity-type semiconductor layer and the second-conductivity-type-side electrode; and

at least one first-conductivity-type-side electrode;

wherein the first-conductivity-type semiconductor layer provides electrical connection in the single light-emitting-unit; and

the light-emitting-device comprises;

an optical coupling layer formed at the main light-extraction direction side of the first-conductivity-type semiconductor layer;

the optical coupling layer being common to the plurality of light-emitting-units, and capable of optical coupling of the plurality of light-emitting-units and distributing a light emitted from one light-emitting-unit to the other light-emitting-units; and

a buffer layer formed at the main light-extraction direction side of the optical coupling layer.

84. :

A process for manufacturing an integrated compound semiconductor light-emitting-device including a plurality of light-emitting-units on a substrate, the process comprising;

depositing an optical coupling layer on a substrate transparent to an emission wavelength;

depositing a thin-film crystal layer having at least a first-conductivity-type semiconductor layer containing a first-conductivity-type cladding layer, an active layer structure, and a second-conductivity-type semiconductor layer containing a second-conductivity-type cladding layer;

forming a second-conductivity-type-side electrode on the surface of the second-conductivity-type semiconductor layer;

a first etching exposing a part of the first-conductivity-type semiconductor layer;

wherein;

(a) the first etching is also for formation of a single light-emitting-point which comprises the active layer structure, the second-conductivity-type semiconductor layer, and the second-conductivity-type-side electrode in each light-emitting-unit, or

(b) the first etching comprises also dividing the active layer structure and the second-conductivity-type semiconductor layer into a plurality of regions, for the formation of the plurality of light-emitting-points in each light-emitting-unit;

forming a first-conductivity-type-side electrode on the surface of the first-conductivity-type semiconductor layer exposed by the first etching;

a second etching removing the thin-film crystal layer from the surface to the boundary of the optical coupling layer or from the surface to an inside portion of the optical coupling layer for forming a light-emitting-unit separation-trench to separate electrically the light-emitting-units from each other; and

a third etching removing at least the first-conductivity-type semiconductor layer, the active layer structure, and the second-conductivity-type semiconductor layer for forming a light-emitting-device separation-trench to separate into a plurality of light-emitting-devices.

86. :

The process according to claim 84 or 85, wherein the third etching is performed;

(i) simultaneously or separately with the second etching and is performed to remove the thin-film crystal layer from the surface to the boundary of the optical coupling layer or from the surface to an inside portion of the optical coupling layer,

(ii) to remove the thin-film crystal layer from the surface to an inside portion of the buffer layer,

(iii) so as to reach the substrate surface, or

(iv) so as to remove a portion of the substrate.

87. :

The process according to claim 84 or 85, wherein the second etching and the third etching are performed by dry etching process using gas selected from the group consisting of Cl₂, BCl₃, SiCl₄, CCl₄, and a combination of two or more of these.

88. :

The process according to claim 87, wherein a patterned metal-fluoride layer, or a metal-fluoride layer selected from the group consisting of SrF₂, AlF₃, MgF₂, BaF₂, CaF₂, and a combination of two or more of these, is used as an etching mask.

89. :

The process according to claim 84 or 85 wherein

the forming a second-conductivity-type-side electrode, the first etching. and the forming a first-conductivity-type-side electrode are carried out in this order, and

the third etching is performed to the depth, from the surface, until removing a portion of the optical coupling layer, until removing a portion of the buffer layer, provided the buffer layer is present, or until reaching the substrate, whereby forming the light-emitting-device separation-trench, and

wherein, the process further comprises;

forming an insulating layer after the first to third etching and before the forming a first-conductivity-type-side electrode; and

forming a scribe region by removing a portion of the insulating layer deposited on the trench bottom surface in the light-emitting-device separation-trench.

90. :

The process according to claim 84 or 85, wherein

the forming a second-conductivity-type-side electrode, the first etching, and the forming a first-conductivity-type-side electrode are carried out in this order, and

the third etching is performed to the depth, from the surface, until removing a portion of the optical coupling layer, until removing a portion of the buffer layer, provided the buffer layer is present, or until reaching the substrate, whereby forming the light-emitting-device separation-trench, and

wherein the process further comprises;

forming an insulating layer after the first to third etching and before the forming a first-conductivity-type-side electrode; and

removing whole of the insulating layer deposited on the trench bottom surface in the light-emitting-device separation-trench and a portion of the insulating layer formed on the sidewall of the light-emitting-device separation-trench near the trench bottom.

85. :

A process for manufacturing an integrated compound semiconductor light-emitting-device including a plurality of light-emitting-units on a support, the process comprising;

depositing a buffer layer and an optical coupling layer on a substrate in this sequence;

depositing a thin-film crystal layer having at least a first-conductivity-type semiconductor layer containing a first-conductivity-type cladding layer, an active layer structure, and a second-conductivity-type semiconductor layer containing a second-conductivity-type cladding layer;

forming a second-conductivity-type-side electrode on the surface of the second-conductivity-type semiconductor layer;

a first etching exposing a part of the first-conductivity-type semiconductor layer;

wherein;

(a) the first etchings is also for formation of a single light-emitting-point which comprises the active layer structure, the second-conductivity-type semiconductor layer, and the second-conductivity-type-side electrode in each light-emitting-unit, or

(b) the first etching comprises also dividing the active layer structure and the second-conductivity-type semiconductor layer into a plurality of regions, for formation of the plurality of light-emitting-points in each light-emitting-unit;

forming a first-conductivity-type-side electrode on the surface of the first-conductivity-type semiconductor layer exposed by the first etching;

a second etching removing the thin-film crystal layer from the surface to the boundary of the optical coupling layer or from the surface to an inside portion of the optical coupling layer for forming a light-emitting-unit separation-trench to separate electrically the light-emitting-units from each other;

a third etching removing at least the first-conductivity-type semiconductor layer, the active layer structure and the second-conductivity-type semiconductor layer for forming a light-emitting-device separation-trench to separate into a plurality of light-emitting-devices; and

removing the substrate.