JP2016171340A - Light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element in which a translucent insulation layer is sandwiched between a semiconductor layer and a translucent conductive layer which composes an electrode thereby to make it possible to reduce deterioration in yield while achieving improvement in light extraction efficiency.SOLUTION: A light emitting element comprises: a semiconductor layer; and an electrode structure having a translucent conductive layer electrically connected with the semiconductor layer, a metal component provided on part of the translucent conductive layer, a first translucent insulation layer provided between the semiconductor layer and the translucent conductive layer and in contact with the semiconductor layer, and a second translucent insulation layer which is provided on and in contact with the first translucent insulation layer and arranged at a position overlapping the metal component. The first translucent insulation layer is arranged in such a manner that an outer edge lies outside an outer edge of the second translucent insulation layer and made of a material having adhesion with the semiconductor layer higher than that of a material of the second translucent insulation layer.SELECTED DRAWING: Figure 1B

Description

  The present invention relates to a light emitting element.

A light-emitting element using a nitride semiconductor is widely used because it can emit light in the near ultraviolet to red region due to its wide band gap characteristics.
A light-emitting element usually has a structure in which an n-type nitride semiconductor, an active layer, and a p-type nitride semiconductor are stacked in this order on a substrate, and each electrode is formed on a p-type layer and a partially exposed n-type layer. Is provided. Based on such a basic structure, various light emitting element structures and electrode structures have been proposed, particularly with the aim of increasing the output.

For example, a structure using a transparent conductive oxide such as ITO for the n-electrode provided in the n-type layer, a structure provided with a translucent insulating film between the electrode and the p-layer provided in the p-layer, etc. have been proposed. (Patent Documents 1 and 2).

JP-A-8-250769 JP-A-9-129921

However, in the structure in which the translucent insulating film is interposed between the p layer and the electrode, the adhesion between the translucent insulating film and the p layer is poor, and the translucent insulating film is peeled off during the manufacturing process. There is concern that the yield will decrease.

The present invention has been made in view of the above problems, and by interposing a translucent insulating layer between the semiconductor layer and the translucent conductive layer constituting the electrode, while improving the light extraction efficiency,
It is an object to provide a light-emitting element that can reduce a decrease in yield.

The present invention includes the following inventions.
A semiconductor layer, a light-transmitting conductive layer electrically connected to the semiconductor layer, a metal member provided on a part of the light-transmitting conductive layer, and the semiconductor layer and the light-transmitting conductive layer A first light-transmitting insulating layer provided in contact with the semiconductor layer, and provided on the first light-transmitting insulating layer, and in plan view,
An electrode structure having a second light-transmissive insulating layer disposed at a position overlapping the metal member;
The outer edge of the first light-transmitting insulating layer is disposed outside the outer edge of the second light-transmitting insulating layer, and the adhesiveness to the semiconductor layer is higher than that of the second light-transmitting insulating layer. A light emitting element formed of a material.

(A) forming a resist layer in a predetermined region on the semiconductor layer;
(B) From the resist layer, a first light-transmitting insulating layer and a second light-transmitting insulating layer are formed in this order by sputtering, and then the resist layer is removed.
(C) Outer edge of the second light-transmitting insulating layer is removed from the obtained first light-transmitting insulating layer and second light-transmitting insulating layer, and the outer edge of the second light-transmitting insulating layer is removed. , Arranged inside the outer edge of the first light-transmissive insulating layer,
(D) forming a light-transmitting conductive layer so as to cover the surface of the first light-transmitting insulating layer, the second light-transmitting insulating layer, and the surrounding semiconductor layer;
(E) A method for manufacturing a light-emitting element, further comprising forming a metal member on the light-transmitting conductive layer and at a position overlapping the second light-transmitting insulating layer.

ADVANTAGE OF THE INVENTION According to this invention, while being able to obtain the light emitting element excellent in light extraction efficiency, the manufacturing method of the light emitting element which can reduce the fall of a yield can be provided.

3 is a schematic plan view for explaining the structure of the light emitting element according to Embodiment 1. FIG. It is a schematic sectional drawing of the A-A 'line | wire of FIG. 1A for demonstrating the structure of the light emitting element which concerns on this Embodiment 1. FIG. It is a schematic plan view for demonstrating the structure of the light emitting element which concerns on this Embodiment 2. FIG. It is a schematic sectional drawing of the A-A 'line | wire of FIG. 2A for demonstrating the structure of the light emitting element which concerns on this Embodiment 2. FIG. It is a schematic sectional process drawing for demonstrating the manufacturing method of the light emitting element which concerns on this embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a light emitting element for embodying the technical idea of the present invention, and the present invention does not specify the light emitting element as follows. Furthermore, in the following description, the same name and reference numeral indicate the same or the same members, and detailed description will be omitted as appropriate.
In the plan views of FIGS. 1A and 2A, the outer edges of the first light-transmissive insulating layers 16 and 65 are not shown, and only the outer edges of the second light-transmissive insulating layers 15 and 65 are shown.

Embodiment 1
As shown in FIGS. 1A and 1B, the light-emitting element 10 according to this embodiment includes a semiconductor layer 24,
And an electrode structure 23.

(Semiconductor layer)
The semiconductor layer 24 is, for example, a first (hereinafter sometimes referred to as “n-type”) semiconductor layer 12 on the substrate 11, optionally through one or more layers (not shown) such as a buffer layer. , Emitting layer 13
A second (hereinafter sometimes referred to as “p-type”) semiconductor layer 14 is laminated in this order.
One region of the semiconductor layer 24 is removed in the thickness direction from the second semiconductor layer 14 side, that is, partly removed, and the first semiconductor layer 12 is exposed therefrom, and the first semiconductor layer 24 other than this exposed region is exposed.
A light emitting layer 13 and a second semiconductor layer 14 are sequentially stacked on another region of the semiconductor layer 12.
In the light emitting device of this embodiment, the semiconductor layer 24 is described as the second semiconductor layer 14 for convenience, but the semiconductor layer may be the first semiconductor layer 12. In this case, the second semiconductor layer 14 is replaced with the first semiconductor layer 12 in the following description.

The first semiconductor layer 12, the light emitting layer 13, and the second semiconductor layer 14 constituting the semiconductor layer 24 are not particularly limited. For example, In _X Al _Y Ga _1- XYN (0 ≦ X, 0 ≦
A nitride compound semiconductor such as Y, X + Y ≦ 1) is preferably used. Each of these nitride semiconductor layers may have a single layer structure, but may have a laminated structure of layers having different compositions and film thicknesses, a superlattice structure, or the like. In particular, the light-emitting layer 13 preferably has a single quantum well or multiple quantum well structure in which thin films that generate quantum effects are stacked.

(substrate)
As the substrate 11, for example, sapphire, spinel, SiC, nitride semiconductor (for example,
A known insulating substrate or conductive substrate such as GaN) or GaAs can be used. The insulating substrate may be finally removed or may not be removed.
When the insulating substrate is not finally removed, the p-side electrode and the n-side electrode are usually formed on the same surface side of the semiconductor layer (see FIGS. 1B and 2B). When the insulating substrate is finally removed or a conductive substrate is used, both the p-side electrode and the n-side electrode may be formed on the same surface side of the semiconductor layer or on different surfaces. It may be formed.

(Electrode structure)
The electrode structure 23 includes a light-transmitting conductive layer 21 electrically connected to the semiconductor layer 24, a metal member 22 provided on a part of the light-transmitting conductive layer 21, and the semiconductor layer and the light-transmitting layer. A first light-transmitting insulating layer 15 provided between the conductive layers and in contact with the semiconductor layer, and provided on the first light-transmitting insulating layer 15 and overlaps the metal member 22 in plan view. And a second light-transmissive insulating layer 16 disposed at the position.
Hereinafter, the translucent conductive layer 21 electrically connected to the second semiconductor layer 14, and the translucent conductive layer 21.
The metal member 22 provided in a part on the top may be collectively referred to as the second electrode 20. That is, the second electrode 20 is in direct contact with a region on the second semiconductor layer 14 where the first light-transmissive insulating layer 15 and the second light-transmissive insulating layer 16 are not formed. Conductive layer 15 and second layer
The second semiconductor layer 14 is ohmically connected so as to cover the translucent insulating layer 16.

(Translucent conductive layer)
The translucent conductive layer 21 of the second electrode 20 is ohmically connected to the second semiconductor layer 14. Here, the ohmic connection has a meaning normally used in this field, and refers to a connection in which the current-voltage characteristic is a straight line or a substantially straight line, for example. It also means that the voltage drop and power loss at the junction during device operation are negligibly small.

Since the translucent conductive layer 21 is intended to supply a uniform current to the second semiconductor layer 14, it is preferable that the translucent conductive layer 21 be disposed on a substantially entire surface of the second semiconductor layer 14 with a large area. Here, the substantially entire surface refers to a region other than the outer edge of the second semiconductor layer 14 exposed on the upper surface and the outer edge of the exposed region of the first semiconductor layer. For example, it is preferably 90% or more of the plane area of the light emitting element, and more preferably 95% or more. Thereby, the contact area of the second electrode 20 to the second semiconductor layer 14 is maximized, and the current flowing from the metal member 22 into the semiconductor layer (particularly the active layer 13) is directly transmitted by the wide transparent conductive layer. The driving voltage can be reduced by reducing the contact resistance. Further, the current can be supplied to the entire surface of the second semiconductor layer with a more uniform current distribution.

The light-transmitting conductive layer 21 transmits 50% or more, 60% or more, 70% or more, or 80% or more of the light emitted from the light emitting layer 13 in order to efficiently extract the light from the light emitting layer 13. It is preferable to form from the material to be made. For example, an oxide containing at least one selected from the group consisting of zinc, indium, tin, magnesium, cadmium, gallium, and lead, specifically, conductivity such as ITO, ZnO ₂ , InO ₂ , SnO, and MgO A single layer film or a stacked film of an oxide film can be given. Moreover, as long as it has translucency, the thin film-like metal or alloy single layer film or laminated film generally used for an electrode may be sufficient.

The thickness of the translucent conductive layer 21 is, for example, 50 nm or more capable of reducing the forward voltage (Vf),
In addition, the thickness is preferably about 300 nm or less, which can reduce light loss due to medium propagation of light emitted from the light emitting layer 13.

(Metal member)
The metal member 22 is a member provided on a part of the translucent conductive layer 21 and to which an external connection member such as a conductive wire can be connected.
The entire metal member 22 is preferably disposed on the translucent conductive layer 21. The metal member 22 is electrically connected to the translucent conductive layer 21 and preferably has a smaller area than the translucent conductive layer 21. That is, the metal member 22 is formed of the second conductivity type semiconductor layer 14.
It is preferable not to contact directly. Second semiconductor layer 14 and first translucent insulating layer 1 described later
6 and the interface between the first light-transmissive insulating layer 16 and the second light-transmissive insulating film layer 15, etc.
This is to avoid absorption of light by the metal member 22 by reflecting light from the active layer 13.
The position, size, and the like of the metal member 22 in the light-emitting element 10 can be appropriately adjusted depending on the shape, size, usage mode (face-up mounting mode, face-down mounting mode, and the like) of the light-emitting element.

The metal member 22 preferably includes a region to be a wire bonding connection. In this case, the area where wire bonding is possible, the size considering the adhesion to the conductive wire used for wire bonding, the laminated structure or surface layer, the thickness enough to withstand the impact during wire bonding, etc. It can be formed by adjusting.
Moreover, in order to supply a current uniformly to the entire surface of the light emitting element 10, the metal member 22 preferably includes a stretched portion that extends from this region in addition to a region that serves as a connection portion for wire bonding. The shape and size of the stretched part are not particularly limited, but for example, 5 to 500 μm
A thickness of about 5 to 50 μm, a side of the light emitting element (for example, a long side) of about 20 to 70%, 3
Those having a length of about 0 to 60% are preferred. Moreover, the extending part may be either linear or curved, and may be one or two or more, and may have a branched structure.
In particular, the connection part of the metal member 22 is preferably arranged to be biased toward the peripheral part or the end part in the light emitting element 10 in order to supply a current uniformly to the entire surface of the light emitting element 10, and the extending part is described later. The first electrode 30 is preferably stretched toward the first electrode 30. For example, in the metal member 22 in the present embodiment, two extending portions extend in a U shape so as to sandwich a first electrode 30 described later from the connecting portion, and each extends from the connecting portion of the first electrode 30. It arrange | positions facing so that it may become substantially parallel to a part.

The metal member 22 is made of zinc (Zn), nickel (Ni), platinum (Pt), palladium (Pd
), Rhodium (Rh), ruthenium (Ru), osmium (Os), iridium (Ir)
, Titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), cobalt (Co), iron (Fe), manganese (Mn),
Molybdenum (Mo), chromium (Cr), tungsten (W), lanthanum (La), copper (C
u), single layer film or laminate of metal or alloy such as silver (Ag), yttrium (Y), gold (Au), aluminum (Al), alloy of Al, Si and Cu (Al-Si-Cu alloy) It can be formed by a film.

In particular, it is preferable that the metal member 22 has a conductive material, such as gold or platinum, that is usually used for connection with other terminals such as wire bonding, disposed on the upper surface side (connection region). Furthermore, materials having good adhesion to the protective film 17 described later, such as Ni, Ti, C
It is preferable to arrange r, Al, W or the like on the upper surface of the metal member 22.

The metal member 22 can be adjusted as appropriate within a range where the total film thickness is about 100 nm to 5 μm. For example, when an Au bump is formed on the metal member 22, the metal member 22 is made relatively thick and eutectic ( In the case of forming a bump, it is suitable to set the metal member 22 to be relatively thin.

(Second translucent insulating layer)
The second light-transmissive insulating layer 15 has a role of reducing the current flowing from the metal member 22 to the light emitting layer 13 immediately below the metal member 22 and spreading the current over a wider range. For this purpose, the second translucent insulating layer 15 is disposed between the second semiconductor layer 12 and the translucent conductive layer 21. In particular, it is preferable that the entire upper surface is disposed in contact with the translucent conductive layer 21. Moreover, as long as it arrange | positions in the position which overlaps with a part of metal member 22 via the translucent conductive layer 21, you may arrange | position in the position which overlaps with the whole.

If the 2nd translucent insulating layer 15 fulfill | performs such a function, the shape, a magnitude | size,
A material, thickness, etc. are not specifically limited, It can adjust suitably.
For example, it may be the same shape and size as the metal member 22, or the shape is the same, slightly smaller (scale of about 1% to tens of percent) or larger (enlargement of about 1% to tens of percent). It is suitable to be. In particular, it is preferable that the metal member 22 is the same as or larger than the metal member 22, and the entire metal member 22 is disposed above the second light-transmissive insulating layer 15. In this case, due to the material of the second light-transmissive insulating layer 15, the light emitted from the light-emitting layer 13 is converted into the second light-transmissive insulating layer 15 and the light-transmissive conductive layer 2.
Since it can be more reliably reflected with a larger area at the interface with 1, the absorption of the emitted light by the metal member 22 can be minimized, and the light reflection efficiency can be improved.

The second light transmissive insulating layer 15 may be made of a light transmissive insulator, for example,
Examples of the oxide film include Al ₂ O ₃ , SiO ₂ , SiN, HfO, TiO ₂ , and SiO _x N _y , and examples of the nitride film include SiN and TiN. It may be a membrane.
In particular, the second light-transmissive insulating layer 15 preferably has a refractive index different from that of the second semiconductor layer 14.
Those having a refractive index smaller than that of the second semiconductor layer 14 are more preferable, and those having a refractive index smaller than that of the first light-transmissive insulating layer 16 described later are more preferable. Specifically, the nitride semiconductor layer is Ga
In the case of the N layer, since the refractive index is about 2.4 to 2.5, the refractive index of the second light-transmissive insulating layer 15 is, for example, about 2.0 or less and about 1.8 or less. It is more preferable to use a single layer film of about 1.6 or less, especially SiO ₂ .
Thus, when the refractive index of the 2nd translucent insulating layer 15 is smaller than the 2nd semiconductor layer 14 (and the 1st translucent insulating layer 16), the 2nd semiconductor layer 14 or the 1st translucent layer. The light from the active layer 13 is reflected at the interface between the light-insulating layer 16 and the second light-transmitting insulating layer 15, in particular, substantially totally reflected at a critical angle or more, and the light loss due to the electrode material thereon is minimized. The light extraction efficiency can be further improved.

The thickness of the second light transmissive insulating layer 15 is, for example, about 100 nm or more, preferably 200 nm so that light from the light emitting layer 13 can be totally reflected at the interface with the first light transmissive insulating layer 16 described later. More preferably, the thickness is equal to or greater than the emission peak wavelength of the light emitting layer (the thickness at which the translucent conductive layer 21 is disposed outside the evanescent field). Thereby, it can suppress that the light which injects more than a critical angle escapes into the translucent conductive layer 21 without being totally reflected. Specifically, the thickness of the second light-transmissive insulating layer 15 is preferably about 100 to 1000 nm in consideration of work time and cost in manufacturing, and is preferably 200 to 500.
About nm is more preferable, and the thickness of the light emitting layer is more than the emission peak wavelength to about 500 nm.

(First translucent insulating layer 16)
The first translucent insulating layer 16 is provided between the semiconductor layer and the translucent conductive layer, in particular, in order to make the second semiconductor layer 14 and the second translucent insulating layer 15 adhere more strongly. It arrange | positions between the semiconductor layer 14 and the 2nd translucent insulating layer 15. FIG. Therefore, the first light-transmissive insulating layer 16 is the second light-transmissive insulating layer 1.
5 is formed of a material having a higher adhesion to the second semiconductor layer 14 than 5. Moreover, it is preferable that the 1st translucent insulating layer 16 is a shape, a magnitude | size, etc. which the 2nd translucent insulating layer 15 does not contact with the 2nd semiconductor layer 14. FIG. The first light-transmissive insulating layer 16 is preferably on the second semiconductor layer 14 and has an outer edge disposed outside the outer edge of the second light-transmissive insulating layer 15. As a result, the second
The first light-transmitting insulating layer 16 can reliably assist the weakness of the adhesion of the light-transmitting insulating layer 15 to the second semiconductor layer 14.
Further, the outer edge of the first light-transmitting insulating layer 16 is not particularly limited with respect to the outer edge of the second light-transmitting insulating layer 15, and is, for example, about several tens nm to several μm, specifically 10 nm to It is preferable that they are arranged outside at a distance of about 2 μm.

The first light transmissive insulating layer 16 preferably has a refractive index different from that of the second light transmissive insulating layer 15, more preferably has a higher refractive index than the second light transmissive insulating layer 15, and the second light transmissive insulating layer 15 has a higher refractive index. It is more preferable that the refractive index is closer to the second semiconductor layer 14 than the conductive insulating layer 15. Specifically, since the GaN layer that is a nitride semiconductor layer has a refractive index of about 2.4 to 2.5, the refractive index of the first light-transmissive insulating layer 16 is equal to or higher than this. Is also small, for example, about 1.6 or more, 1.8
More than about 2.0 or more is preferable.

The first light-transmitting insulating layer 16 is formed of a material having higher adhesion to the semiconductor layer than the second light-transmitting insulating layer, so that the normally used light-transmitting conductive layer and the semiconductor layer are formed. The adhesion to the semiconductor layer can be ensured as compared with the insulating layer disposed therebetween, and the current can be reliably supplied to the semiconductor layer with a more uniform current distribution.
Here, the adhesion of the first light-transmissive insulating layer 16 to the semiconductor layer varies depending on the composition of the first light-transmissive insulating layer 16 and the semiconductor layer, and also depends on the composition of the second light-transmissive insulating layer. However, the magnitude of the adhesion required between the first light-transmissive insulating layer 16 and the semiconductor layer varies. Therefore, the material which comprises the 1st translucent insulating layer 16 can be suitably selected with the 2nd translucent insulating layer and semiconductor layer to be used.

The first light-transmissive insulating layer 16 is made of, for example, a material selected from the group consisting of niobium oxide, titanium oxide, alumina, zirconium oxide, hafnium oxide, yttrium oxide, zinc oxide, tantalum oxide, magnesium oxide, and bismuth titanate. Is mentioned. Of these, niobium oxide is preferable. In particular, when the second light-transmitting insulating layer 15 is silicon oxide, the first light-transmitting insulating layer 16 is made of niobium oxide, so that the adhesion with the second semiconductor layer 14 can be further strengthened. it can. In addition, the refractive index difference between the second semiconductor layer 14 and the first light-transmissive insulating layer 16 can be reduced to an extent that there is almost no difference, while the first light-transmissive insulating layer 16 and the second light-transmissive insulating layer 15 are reduced.
Can be increased, the critical angle at the interface between the first light-transmissive insulating layer 16 and the second light-transmissive insulating layer 15 can be set small, and the light from the light-emitting layer 13 can be efficiently produced. Can be totally reflected. For this reason, it is possible to minimize light absorption by the second electrode or a part of the first electrode, which will be described later, and to further improve the light extraction efficiency.

The first light-transmissive insulating layer 16 has a thickness of 1 nm or more in consideration of adhesion with the second semiconductor layer 14.
Those having a thickness of 3 nm or more, 5 nm or more, 10 nm or more, and a thickness of 100 nm or less and a thickness of 50 nm or less that can reduce light absorption by the first light-transmissive insulating layer 16 itself are preferable. Specifically, about 1-100 nm is preferable, about 3-100 nm is more preferable, and 10-50 nm is further more preferable.
Such a first light-transmissive insulating layer 16 is an extremely thin film and is interposed between the second semiconductor layer 14 and the second light-transmissive insulating layer 15, so that the second light-transmissive insulating layer 15 has a first thickness. 2 Adhesiveness to the semiconductor layer 14 can be ensured, and the light-emitting element can be manufactured with a high yield without the second light-transmitting insulating layer 15 being peeled off during the manufacturing process.
Moreover, the 1st translucent insulating layer 16 in which the outer edge was provided in the outer side rather than the 2nd translucent insulating layer 15,
Along with the second light-transmissive insulating layer 15 described above, a current that is about to flow from the metal member 22 to the active layer 13 immediately below the metal member 22 can be diffused in the horizontal direction.
Furthermore, the first light-transmitting insulating layer 15 and the second light-transmitting insulating layer 16 having such a structure are:
The light from the active layer 13 can be reflected at the interface. Therefore, light absorption by the metal member 22 can be reduced.

(First electrode 30)
A first electrode 30 is formed on the upper surface of the first semiconductor layer 12 of the light emitting element 10 (an area other than the area where the active layer 13 and the second semiconductor layer 14 are provided). The electrode 30 may be in direct contact with the first semiconductor layer 12 and may be in ohmic connection. For example, Al
, Rh, W, Mo, Ti, V and other metal materials, ZnO, In ₂ O ₃ , SnO ₂ , conductive oxides such as ITO, and the like. The first electrode 30 may have a single layer structure or a laminated structure. Moreover, you may have the same laminated structure as the 2nd electrode 21 mentioned above. That is, the ohmic-connected translucent conductive layer 31 and the metal member 32 disposed on the translucent conductive layer 31.
You may have. By selecting this laminated structure, it is possible to simplify the manufacturing process by simultaneously laminating and patterning simultaneously when forming the laminated structure for the second electrode 20.

The first electrode 30, particularly the translucent conductive layer 31, is intended to supply a uniform current to the first semiconductor layer 12, and therefore has a wide area on the substantially entire surface of the first semiconductor layer 12. Preferably it is formed. As a result, the contact area of the first electrode 30 to the first semiconductor layer 12 can be maximized, the contact resistance can be reduced and the drive voltage can be reduced, and the current can be effectively transferred to the entire surface of the first semiconductor layer 12. Can be supplied to.

(Protective film 17)
A protective film 32 is usually formed on the side surface of the semiconductor layer, a part of the second electrode 20, an exposed region of the first semiconductor layer 12, and a part of the surface of the first electrode 30.
When the protective film 17 is formed of a material that hardly absorbs light, absorption of light from the light emitting layer 13 can be kept to a minimum, and light extraction efficiency can be improved. For example, Si, Ti, V,
An oxide film containing at least one element selected from the group consisting of Zr, Nb, Hf, Ta,
Examples thereof include a nitride film and an oxynitride film. In _{particular, SiO 2, ZrO 2, SiN} , BN, SiC
, SiOC, AlN, AlGaN. The protective film 17 may be a single layer film or a laminated film made of a single material, or may be a laminated film made of different materials.
The thickness of the protective film 17 is, for example, 10 to 10 to protect the light emitting element from the external environment.
About 2000 nm is suitable, and about 100 to 1000 nm is more preferable.

(Manufacturing method of light emitting element)
In the method for manufacturing a light emitting device of the present invention, first, (a) a resist layer is formed in a predetermined region on the semiconductor layer.
The semiconductor layer can be formed by appropriately adjusting conditions and the like in order to obtain the above-described stacked structure of the semiconductor layer by a method usually used in this field.
For example, MOVPE, metal organic chemical vapor deposition (MOCVD), hydride vapor deposition (
Examples of the film forming method include HVPE) and molecular beam epitaxial growth (MBE).

Next, (b) a first light-transmitting insulating layer and a second light-transmitting insulating layer are formed in this order by sputtering on the resist layer, and then the resist layer is removed.
For example, a resist layer having an opening is formed in a region where the first light-transmitting insulating layer and the second light-transmitting insulating layer are intended to be formed, and the first light-transmitting insulating layer and the second light-transmitting insulating layer are formed on the resist layer by sputtering. A material film of the translucent insulating layer is formed on the second semiconductor layer in this order. After that, by removing the resist layer and the material films of the first light-transmitting insulating layer and the second light-transmitting insulating layer formed thereon (lift-off method), as shown in FIG. A first light-transmitting insulating layer 16 and a second light-transmitting insulating layer 15 patterned into a desired shape are formed.
In addition, it is preferable that the conditions of the sputtering method when forming the first light-transmitting insulating layer be more relaxed than the conditions when forming the second light-transmitting insulating layer. Usually, when the first light-transmitting insulating layer and the second light-transmitting insulating layer are formed by sputtering, the sputtered particles collide with the surface of the semiconductor layer as shown in FIG. The damage region 14a due to surface roughness, crystal distortion, etc. is formed, but by reducing the sputtering conditions, the sputtering effect on the surface of the semiconductor layer when the first light-transmissive insulating layer is formed is reduced. Thus, damage, roughness, crystal distortion, and the like on the surface of the semiconductor layer can be avoided, and the adhesion of the first light-transmissive insulating layer 16 to the semiconductor layer 14 can be further improved.

The first light-transmitting insulating layer formed here is preferably formed of a material having higher adhesion to the semiconductor layer than the second light-transmitting insulating layer formed on the first light-transmitting insulating layer. It is preferable to have a refractive index closer to that of the semiconductor layer than the conductive insulating layer. Moreover, it is preferable that a 2nd translucent insulating layer has a refractive index smaller than the refractive index of a 1st translucent insulating layer.

Thereafter, (c) of the obtained first translucent insulating layer 16 and second translucent insulating layer 15, the second
The outer edge of the translucent insulating layer 15 is removed, and the second translucent insulating layer 16 is removed as shown in FIG.
The outer edge is arranged inside the outer edge of the first light-transmissive insulating layer 16.
Such removal can be performed using, for example, a difference in etching rate depending on the material constituting these layers. Specifically, the difference in etching rate can be utilized by controlling the etchant selection by dry etching or wet etching, the etching time, power in dry etching, RF, the concentration or purity of the etchant, and the like.
In particular, an aqueous solution containing hydrogen fluoride and ammonium fluoride (buffered hydrofluoric acid, BHF
Wet etching using) is preferable. The buffered hydrofluoric acid can control the etching rate by adjusting the concentration of the aqueous solution. For example, wet etching may be performed at a temperature of about 15 to 50 ° C. for about 0.5 to 30 minutes.
By performing such processing, normally, when a relatively thick transparent insulating layer is patterned by the lift-off method, burrs and the like generated at the end of the transparent insulating layer are effectively removed. be able to. Further, since the outer edge of the second light-transmitting insulating layer can be disposed inside the outer edge of the first light-transmitting insulating layer by etching, the second light-transmitting insulating layer is in direct contact with the semiconductor layer. It can be avoided, and peeling of the second light-transmitting insulating layer due to weakness of the contact can be prevented. In addition, since the end face of the second light-transmitting insulating layer can be further away from the semiconductor layer, stress in the vicinity of the end faces of the semiconductor layer, the first light-transmitting insulating layer, and the second light-transmitting insulating layer is avoided. Thus, peeling of the second light-transmitting insulating layer can be more effectively prevented.

Subsequently, as shown in FIG. 3 (c), (d) the light transmission is performed so as to cover the surfaces of the first light transmission insulating layer 16, the second light transmission insulating layer 15, and the surrounding semiconductor layers. The conductive conductive layer 21 is formed. Further, (e) a metal member 22 is formed on the light transmissive conductive layer 21 at a position overlapping the second light transmissive insulating layer 15.
Here, the translucent conductive layer 21 and the metal member 22 can be formed by patterning into a desired shape by a method similar to the formation of an electrode in the field, for example, photolithography and an etching method.

In the step (a), the second semiconductor layer and the light emitting layer, and optionally a part of the first semiconductor layer in the thickness direction are removed using an etching method such as photolithography and RIE.
By exposing the semiconductor layer, a semiconductor layer including a first semiconductor layer, a light emitting layer provided on one region of the first semiconductor layer, and a second semiconductor layer provided on the light emitting layer is formed.

After these steps, a protective film 17 may be formed. The protective film 17 can be formed by a method known in the art. For example, vapor deposition, sputtering, reactive sputtering, E
CR plasma sputtering method, magnetron sputtering method, ion beam assisted deposition method, ion plating method, laser ablation method, CVD method, spray method, spin coating method, dipping method, or a combination of these methods, or these Various methods such as a method of combining the above method and oxidation treatment (heat treatment) can be used.

Embodiment 2
As shown in FIGS. 2A and 2B, the light emitting device 40 according to this embodiment includes a semiconductor layer and electrode structures 23 and 33.
In the light emitting device 40 of this embodiment, in addition to the electrode structure 23 formed on the second semiconductor layer 14, the light emitting device of Embodiment 1 is provided except that the electrode structure 33 is also disposed on the first semiconductor layer 12. 10 has substantially the same configuration.

That is, as shown in FIG. 2A and FIG. 2B, between the translucent conductive layer 51 and the first semiconductor layer 12, as between the second semiconductor layer 14 and the translucent conductive layer 21, Two translucent insulating layers 65 and a first translucent insulating layer 66 are arranged. In this case, the second light-transmissive insulating layer 65 may be disposed at a position overlapping with the whole metal member 52, but is preferably disposed at a position overlapping with a part of the metal member 52. In particular, the second translucent insulating layer 65 overlaps with a part of the metal member 52 and is disposed on the outer edge side of the light emitting element so that the translucent conductive layer 51 is in contact with the first semiconductor layer 12. Is preferred. Thereby, it is possible to more preferably realize uniform supply of current to the light emitting layer 13.

In such a light-emitting element, in the step (a) described above, a resist layer having an opening is formed on the second semiconductor layer 14 and another region (exposed region) of the first semiconductor layer 12, and this resist layer is formed. It can form by performing process (b)-(e) mentioned above using.

When the electrode structure 33 on the first electrode 50 side and the electrode structure 23 on the second electrode 20 side are formed of the same material film, the region to be formed, for example, another region of the first semiconductor layer ( A resist layer having an opening on the exposed region) and the second semiconductor layer is patterned, and the resist layer can be used as a mask to form simultaneously.

In addition to the formation of the electrode structure 23 on the second semiconductor layer 14, the step (a) described above is performed.
, A resist layer having an opening is formed on another region (exposed region) of the first semiconductor layer 12, and the steps similar to the steps (b) to (e) described above are performed using this resist layer. The electrode structure 33 can be separately formed on the second semiconductor layer 14 and the first semiconductor layer 12.

Hereinafter, a light emitting device and a manufacturing method thereof according to an embodiment of the present invention will be described in detail.
Example 1
The light emitting device 10 of this example includes a semiconductor layer 24 and an electrode structure 23 as shown in FIGS. 1A and 1B.
The semiconductor layer 24 is formed on the substrate 11 made of sapphire via a plurality of layers (not shown) such as a buffer layer, the first (for example, n-type) semiconductor layer 12, the light emitting layer 13, and the second (for example, p). Type)
A semiconductor layer in which the semiconductor layers 14 are stacked in this order is formed. The semiconductor layer is partially removed to form an exposed region from which the n-type semiconductor layer 12 is exposed.

On the upper surface of the second semiconductor layer 14, a second electrode 20 made of a light-transmitting conductive layer 21 made of ITO and a metal member 22 is formed on the entire surface excluding the entire outer periphery of the light emitting element 10 and the entire outer periphery of the exposed region in the element. Is formed.
The translucent conductive layer 21 is in direct contact with the second semiconductor layer 14 except for a part thereof and is in ohmic contact.
A metal member 22 that functions as a pad electrode to which an external connection member such as a conductive wire is electrically connected is disposed on the translucent conductive layer 21. With this metal member 22, current can be supplied to the entire second semiconductor layer 14 through the translucent conductive layer 21.
For example, the metal member 22 is configured by sequentially laminating an Rh film (film thickness: 100 nm), a W film (film thickness: 50 nm), and an Au film (film thickness: 500 nm) from the semiconductor layer side.

Between the second semiconductor layer 14 and the translucent conductive layer 21, a first translucent insulating layer 16 made of niobium oxide and a second translucent insulating layer 15 made of silicon oxide are provided from the semiconductor layer side. Arranged in order.
An electrode structure 23 is formed by the above-described translucent conductive layer 21, metal member 22, first translucent insulating layer 16, and second translucent insulating layer 15.
The second light transmissive insulating layer 15 has an outer edge located outside the outer edge of the first light transmissive insulating layer 16, that is, the entire surface of the second light transmissive insulating layer 15 is the first light transmissive insulating layer 15. It is laminated so as to be disposed on the light insulating layer 16.
In addition, the second translucent insulating layer 15 has an outer edge located outside the outer edge of the metal member 22, that is, the entire surface of the metal member 22 is second through the translucent conductive layer 21. It is formed so as to be located on the translucent insulating layer 15.

On the upper surface of the first semiconductor layer 12, the second electrode 2 composed of the translucent conductive layer 21 and the metal member 22.
The first electrode 30 made of the light-transmitting conductive layer 31 and the metal member 32 is formed of the same material as 0, and the entire surface of the light-transmitting conductive layer 31 is in direct contact with the first semiconductor layer 12. And ohmic connected.

In the light emitting element 10 of this example, for example, the element size is 700 × 300 μm, the total area of the first light-transmissive insulating layer 16 connected to the second semiconductor layer 14 is 20000 μm ² , and the light-transmissive conductive film (
The contact area between the ITO and the second semiconductor layer 14 is 150000 μm ² .

Such a light-emitting element can be manufactured by the following manufacturing method.
(Formation of semiconductor layer)
Using a MOVPE reactor on a substrate 11 made of sapphire, a buffer layer made of Al _0.1 Ga _0.9 N is 10 nm, a non-doped GaN layer is 1.5 μm, and a first semiconductor layer 12 is an n-type contact made of Si-doped GaN. 2.165 μm layer, GaN layer (4 nm)
And InGaN layer (2 nm) alternately stacked 10 times superlattice n-type cladding layer 64 nm
Form. On top of that, a well layer made of In _0.3 Ga _0.7 N with a thickness of 3 nm and a barrier layer made of undoped GaN with a thickness of 15 nm are stacked alternately and alternately six layers from the barrier layer, Finally, a light emitting layer 13 (total film thickness: 123 nm) having a multiple quantum well structure formed by stacking barrier layers is formed. On top of that, as the second semiconductor layer 14, Mg-doped Al _0.1 G
a _0.9 μm superlattice p-type cladding layer in which N _0.9 layers (4 nm) and Mg-doped InGaN layers (2 nm) are alternately stacked 10 times, and 0 p-type contact layer made of Mg-doped GaN
. The wafer was grown in this order with a film thickness of 5 μm.

The obtained wafer was annealed in a reaction vessel at 600 ° C. in a nitrogen atmosphere to further reduce the resistance of the p-type cladding layer and the p-type contact layer.

(Formation of electrodes)
After annealing, the wafer is taken out of the reaction vessel, a resist pattern having a predetermined pattern is formed on the second semiconductor layer 14, and niobium oxide and silicon oxide are deposited by sputtering using this resist pattern as a mask. Films were sequentially formed. Thereafter, using the lift-off method, as shown in FIG. 3A, these films are patterned into a desired shape,
A first light-transmitting insulating layer 16 and a second light-transmitting insulating layer 15 were formed on the semiconductor layer 14. In addition,
On the surface of the semiconductor layer 14 on which the first light-transmissive insulating layer 16 and the second light-transmissive insulating layer 15 are stacked,
A damaged region 14a is generated due to the collision of particles during sputtering. Further, since the first light-transmissive insulating layer 16 is much thinner than the second light-transmissive insulating layer 15, burrs and the like due to the lift-off method hardly occur.

Subsequently, wet etching is performed at room temperature using buffered hydrofluoric acid, and the second edge of the second light-transmitting insulating layer 15 is positioned so as to be located inside the outer edge of the first light-transmitting insulating layer 16. The translucent insulating layer 15 was processed. The first light-transmitting insulating layer 16 is hardly etched by this wet etching, and the burrs generated on the periphery of the second light-transmitting insulating layer 16 and the side surfaces thereof are etched, and the size thereof is slightly reduced. .
After that, a film made of ITO is formed on the surface of the obtained wafer and patterned, so that the second semiconductor layer 14 and the exposed first semiconductor layer 12 are substantially as shown in FIG. Translucent conductive layers 21 and 31 were formed on the entire surface, respectively.
Next, on the obtained wafer, an Rh film (thickness 100 nm), a W film (thickness 50 nm) and A
The u films (thickness 500 nm) are sequentially laminated and patterned into the shape described above to form the metal members 22 and 32 as shown in FIG. 3C, and the second electrode 20 and the first electrode 30 are formed. Formed.

Furthermore, the substrate 11 made of sapphire was polished from the back side to form a thin film, and then scribed to form a light emitting element chip.

Example 2
As shown in FIGS. 2A and 2B, the light-emitting element 40 of Example 2 includes the first semiconductor layer 12.
The structure is the same as that of the light-emitting element 10 according to the first embodiment except that the electrode structure 33 is disposed on the substrate.
That is, the first light-transmissive insulating layer 66 and the second light-transmissive insulating layer 65 are arranged between the first semiconductor layer 12 and the first electrode 50 formed thereon.
Here, the first light-transmissive insulating layer 66 and the second light-transmissive insulating layer 65 on the first semiconductor layer 12 are formed of the same material as those on the second semiconductor layer 14. Translucent insulating layer 6
The outer edge of 5 is located inside the outer edge of the first light-transmissive insulating layer 66.
The outer edge of the second light-transmissive insulating layer 65 is the inner side of the outer edge of the light-transmissive conductive layer 51, and
The metal member 52 is disposed outside the outer edge.

(Evaluation 1 of light emitting element)
The wafer obtained in the same manner as in Example 1 except that the thickness of the second light-transmitting insulating layer (silicon oxide) / first light-transmitting insulating layer (niobium oxide) is changed, and is peeled off due to thermal stress during manufacturing. The number of the second light-transmitting insulating layers is counted by an automatic appearance device, and the peeling rate of the second light-transmitting insulating layer (p
pm) was calculated. In addition, a light emitting element separated from a wafer is a bullet type (diameter 5 mm).
The forward voltage (V) and the light output (mW) when the device was mounted in the light emitting device and light was emitted in the normal operating current range were also confirmed.
As a comparative example, a light emitting device obtained in the same manner as described above was used except that the first light-transmissive insulating layer was not formed.

評価例１Ａ〜１Ｄは、比較例２と比べて光出力および順方向電圧を維持したまま、顕著
に剥がれ率を低減することができた。また、第１透光性絶縁層の厚みが大きくなるにつれ
て、剥がれ率をより低減することができた。

Evaluation Examples 1A to 1D were able to significantly reduce the peeling rate while maintaining the light output and the forward voltage as compared with Comparative Example 2. Moreover, the peeling rate could be further reduced as the thickness of the first light-transmissive insulating layer was increased.

(Evaluation 2 of light emitting element)
The wafer obtained in the same manner as in Example 1 except that the thickness of the second light-transmitting insulating layer (silicon oxide) / first light-transmitting insulating layer (niobium oxide) is changed, and is peeled off due to thermal stress during manufacturing. The number of the second light-transmitting insulating layers is counted by an automatic appearance device, and the peeling rate of the second light-transmitting insulating layer (p
pm) was calculated. In addition, a light emitting element separated from a wafer is a bullet type (diameter 5 mm).
The forward voltage (V) and the light output (mW) when the device was mounted in the light emitting device and light was emitted in the normal operating current range were also confirmed.
As a comparative example, a light emitting device obtained in the same manner as described above was used except that the first light-transmissive insulating layer was not formed.

評価例２Ａ〜２Ｄはいずれも、比較例２と比べて光出力および順方向電圧を維持したま
ま、顕著に剥がれ率を低減することができた。また、第１透光性絶縁層の厚みが大きくな
る、特に１０ｎｍ以上のとき剥がれをなくすことができた。
なお、本評価に用いた各サンプルは、評価１に用いたサンプルと同様の条件で作成した
ものではあるが、評価１とは別のウェハから得られたサンプルであるため、評価例１Ｄと
評価例２Ａとで異なる剥がれ率を示している。ただし、同一ウェハから得られたサンプル
同士を比較する場合、剥がれ率には同様の傾向が現れるため、評価２における剥がれ率の
比較自体に問題は無いものとする。

In each of Evaluation Examples 2A to 2D, it was possible to significantly reduce the peeling rate while maintaining the light output and the forward voltage as compared with Comparative Example 2. Moreover, peeling was able to be eliminated when the thickness of the 1st translucent insulating layer became large, especially 10 nm or more.
Each sample used for this evaluation was prepared under the same conditions as the sample used for evaluation 1, but it was a sample obtained from a wafer different from evaluation 1, and therefore, it was evaluated as evaluation example 1D. The peeling rate different from Example 2A is shown. However, when samples obtained from the same wafer are compared with each other, a similar tendency appears in the peeling rate, and therefore there is no problem in the comparison of the peeling rate in Evaluation 2.

  The light-emitting element according to the present invention can be used for various light-emitting devices such as illumination light sources, various indicator light sources, in-vehicle light sources, display light sources, liquid crystal backlight light sources, sensor light sources, and traffic lights. it can.

DESCRIPTION OF SYMBOLS 10, 40 Light emitting element 11 Substrate 12 1st semiconductor layer 13 Light emitting layer 14 2nd semiconductor layer 14a Damage area | region 15,65 2nd translucent insulating layer 16,66 1st translucent insulating layer 17 Protective film 20 2nd electrode 30 1st electrode 21, 31, 51 Translucent conductive layer 22, 32, 52 Metal member 23, 33 Electrode structure 24 Semiconductor layer

Claims (7)

A semiconductor layer, a light-transmitting conductive layer electrically connected to the semiconductor layer, a metal member provided on a part of the light-transmitting conductive layer, and the semiconductor layer and the light-transmitting conductive layer A first light-transmitting insulating layer provided in contact with the semiconductor layer, and provided in contact with the first light-transmitting insulating layer and disposed in a position overlapping the metal member in plan view. An electrode structure having a second light-transmitting insulating layer formed,
The outer edge of the first light-transmitting insulating layer is disposed outside the outer edge of the second light-transmitting insulating layer, and has a higher adhesion to the semiconductor layer than the second light-transmitting insulating layer. A light-emitting element formed using a material.   2. The light emitting device according to claim 1, wherein the second light transmissive insulating layer has a refractive index smaller than a refractive index of the first light transmissive insulating layer.   3. The light-emitting element according to claim 1, wherein the first light-transmissive insulating layer has a refractive index closer to a refractive index of the semiconductor layer than the second light-transmissive insulating layer.   The light emitting device according to any one of claims 1 to 3, wherein the first light-transmissive insulating layer has a thickness of 1 nm to 100 nm.   The light emitting device according to any one of claims 1 to 4, wherein the second light-transmissive insulating layer has a thickness of 100 nm or more.   The first translucent insulating layer is formed of a material selected from the group consisting of niobium oxide, titanium oxide, alumina, zirconium oxide, hafnium oxide, yttrium oxide, zinc oxide, tantalum oxide, magnesium oxide, and bismuth titanate. The light emitting device according to claim 1. The semiconductor layer includes a first semiconductor layer, a light emitting layer provided on a region of the first semiconductor layer, and a second semiconductor layer provided on the light emitting layer,
The light emitting device according to claim 1, wherein the electrode structure is provided on another region of the first semiconductor layer and on the second semiconductor layer.

Images