JP6601243B2 - Light emitting device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a light emitting device and a method for manufacturing the same.

  An n-side semiconductor layer, an active layer, and a p-side semiconductor layer are sequentially stacked on the upper surface of the sapphire substrate, and light is reflected above the p-side semiconductor layer in order to effectively extract light from the active layer from the sapphire substrate side. A light-emitting element having a film is known. For example, in Patent Document 1, a translucent conductive film made of, for example, ITO (indium tin oxide) is provided on substantially the entire upper surface of the p-side semiconductor layer. Discloses a light emitting device in which a DBR (Distributed Bragg Reflector) film is provided on the upper surface of the substrate.

Japanese Patent No. 5743806

  However, for example, in the case where an opening is provided in the DBR film in order to provide a pad electrode that is electrically connected to the light-transmitting conductive film, a portion in which the end surface of the opening is inclined and the thickness of the DBR film is thin may occur. . In such a thin portion, the number of laminated multilayer dielectric films is reduced, so that the light reflectance is lowered. As a result, the light extraction efficiency of the light emitting element may be reduced.

  An object of the present invention is to provide a light-emitting element with improved light extraction efficiency.

  A light-emitting element according to the present invention includes a semiconductor stacked body in which an n-side semiconductor layer and a p-side semiconductor layer are sequentially provided upward, and a light-transmitting element provided on a part of the upper surface of the p-side semiconductor layer. An insulating film; a p-side transmissive electrode provided on an upper surface of the p-side semiconductor layer; and the semiconductor laminate and the p-side transmissive electrode. A light reflection film having an opening in a part above the photoelectrode, and a p-electrode electrically connected to the p-side translucent electrode through the opening, the light reflection film comprising: A first portion located in a region above the semiconductor stacked body and not provided with the p-side translucent electrode, and a second portion located above the p-side translucent electrode. The first portion is bent more than the first dielectric layer and the first dielectric layer, with the lowermost layer being the first dielectric layer. Becomes a high rate second dielectric layer are laminated alternately, the second site, the bottom layer as an air layer, and the air layer, and the second dielectric layer are laminated alternately.

  The method for manufacturing a light-emitting element according to the present invention is a semiconductor stacked body in which an n-side semiconductor layer and a p-side semiconductor layer are sequentially provided upward, and is provided on a part of the upper surface of the p-side semiconductor layer. Preparing the semiconductor stacked body provided with the translucent insulating film and the p-side translucent electrode that covers the insulating film and is provided on the upper surface of the p-side semiconductor layer; Light in which the first dielectric layer and the second dielectric layer having a refractive index higher than that of the first dielectric layer are alternately laminated above the semiconductor laminated body, with the lowermost layer being the first dielectric layer A step of providing a reflection film, a step of providing an opening in the light reflection film in a portion above the p-side translucent electrode by a dry etching method, and wet etching an end surface of the opening, The p-side translucent electrode is disposed when viewed from the upper surface side. And a step of removing the first dielectric layer in the region.

  According to the light emitting device and the manufacturing method thereof according to the present invention, it is possible to provide a light emitting device with improved light extraction efficiency.

It is a top view which shows the structure of the light emitting element which concerns on embodiment. It is a top view which shows the structure of the light emitting element which concerns on embodiment, and is the enlarged view of the area | region IB shown by the dashed-two dotted line in FIG. 1A. It is sectional drawing which shows the structure of the light emitting element which concerns on embodiment, and shows the cross section in the IC-IC line | wire of FIG. 1B. It is sectional drawing which shows the structure of the n side electrode structure in the light emitting element which concerns on embodiment, and is the enlarged view of area | region ID shown with the dashed-two dotted line in FIG. 1C. It is sectional drawing which shows the structure of the p side electrode structure in the light emitting element which concerns on embodiment, and is the enlarged view of area | region IE shown with the dashed-two dotted line in FIG. 1C. It is a top view for demonstrating the laminated structure of the light emitting element which concerns on embodiment, and shows the arrangement | positioning area | region of an n side semiconductor layer and a p side semiconductor layer. It is a top view for demonstrating the laminated structure of the light emitting element which concerns on embodiment, and shows the arrangement | positioning area | region of a 1st insulating film. It is a top view for demonstrating the laminated structure of the light emitting element which concerns on embodiment, and shows the arrangement | positioning area | region of an n side translucent electrode and a p side translucent electrode. It is a top view for demonstrating the laminated structure of the light emitting element which concerns on embodiment, and shows the arrangement | positioning area | region of a light reflection film. It is a top view for demonstrating the laminated structure of the light emitting element which concerns on embodiment, and shows the arrangement | positioning area | region of n pad electrode and p pad electrode. It is a top view for demonstrating the laminated structure of the light emitting element which concerns on embodiment, and shows the arrangement | positioning area | region of a 2nd insulating film. It is a top view for demonstrating the laminated structure of the light emitting element which concerns on embodiment, and shows the arrangement | positioning area | region of the electrode for external connection. It is a flowchart which shows the procedure of the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows a semiconductor laminated body formation process in the semiconductor laminated body preparation process of the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows the 1st insulating film formation process in the semiconductor laminated body preparation process of the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows a translucent electrode formation process in the semiconductor laminated body preparation process of the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows the light reflection film formation process in the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows a dielectric multilayer film formation process in the light reflection film formation process of the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows an opening part formation process in the light reflection film formation process of the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows the 1st dielectric material layer removal process in the light reflection film formation process of the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows a pad electrode formation process in the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows the 2nd insulating film formation process in the manufacturing method of the light emitting element which concerns on embodiment. It is sectional drawing which shows the external connection electrode formation process in the manufacturing method of the light emitting element which concerns on embodiment.

Hereinafter, the light emitting device and the manufacturing method thereof according to the embodiment will be described.
The drawings referred to in the following description schematically show the embodiment, and therefore, the scale, interval, positional relationship, etc. of each member are exaggerated, or some of the members are not shown. There is a case. In addition, the scale and interval of each member may not match in the plan view and the cross-sectional view thereof. Moreover, in the following description, the same name and the code | symbol are showing the same or the same member in principle, and suppose that detailed description is abbreviate | omitted suitably.
Further, in this specification, “upper”, “lower” and the like indicate relative positions between components, and are not intended to indicate absolute positions.

[Configuration of Light Emitting Element]
With reference to FIG. 1A-FIG. 2G, the light emitting element 1 which concerns on embodiment is demonstrated.
2A to 2G show a state in which layers are sequentially stacked from the lower layer side in order to explain the stacked structure of the light emitting element 1. 2A to 2G are plan views, but for convenience, the uppermost layer in each drawing is hatched.

As shown in FIGS. 1A to 1E, the light emitting element 1 according to the present embodiment has a substantially square outer edge shape when viewed from above, and includes a substrate 11, a semiconductor stacked body 12, an n-side electrode structure 13, The p-side electrode structure 14, the first insulating film 15, the light reflecting film 16, the second insulating film 17, and the external connection electrodes 18n and 18p are provided.
In the light emitting element 1, the upper surface side on which the external connection electrodes 18n and 18p are provided is a mounting surface, and the lower surface side on which the substrate 11 is provided is a light extraction surface.
Hereinafter, each member will be described in detail sequentially.

(substrate)
The substrate 11 supports the semiconductor stacked body 12. Further, the substrate 11 may be a growth substrate for epitaxially growing the semiconductor stacked body 12. As the substrate 11, for example, when a nitride semiconductor is used for the semiconductor stacked body 12, a sapphire (Al ₂ O ₃ ) substrate can be used.
The substrate 11 can be removed after the semiconductor laminate 12 is formed on the upper surface and a support member such as a resin is provided on the upper surface of the semiconductor laminate 12. In the case where the light-emitting element 1 includes the substrate 11, the substrate 11 preferably has good translucency.

(Semiconductor laminate)
The semiconductor stacked body 12 is formed by sequentially stacking an n-side semiconductor layer 12n and a p-side semiconductor layer 12p on an upper surface that is one main surface of the substrate 11. As shown in FIG. 1C, an active layer 12a is preferably provided between the n-side semiconductor layer 12n and the p-side semiconductor layer 12p.

  In the semiconductor stacked body 12, the p-side semiconductor layer 12p and the active layer 12a are not partially present, that is, recessed from the surface of the p-side semiconductor layer 12p, and the n-side semiconductor layer 12n is formed on the upper surface side of the p-side semiconductor layer 12p. The 1st exposed part 12b and the 2nd exposed part 12c which are the area | regions exposed from are formed. In FIG. 2A, the hatched area with the upward-sloping diagonal line is the area where the p-side semiconductor layer 12p is disposed, and the hatched area with the upward-sloping diagonal line is the first exposed portion 12b and the second exposed portion. 12c.

The first exposed portion 12b has a substantially circular shape when viewed from above, and the plurality of first exposed portions 12b are formed on the entire upper surface side of the semiconductor stacked body 12 except for the middle region in the plan view shown in FIG. 2A. They are arranged in a staggered pattern at substantially equal intervals.
The second exposed portion 12c is provided along the outer periphery of the light emitting element 1 in a top view. The second exposed portion 12c is provided on a dicing street that partitions the light emitting elements 1 when the plurality of light emitting elements 1 are manufactured by a wafer level process.

n-side semiconductor layer 12n, the active layer 12a and the p-side semiconductor layer 12p _{is, In X Al Y Ga 1-} X-Y N (0 ≦ X, 0 ≦ Y, X + Y <1) is a nitride semiconductor such as used.

(Electrode structure)
As shown in FIG. 1C, the light-emitting element 1 includes an n-side electrode structure 13 that is electrically connected to the n-side semiconductor layer 12n in the first exposed portion 12b, and a p-side semiconductor on the upper surface of the p-side semiconductor layer 12p. A p-side electrode structure 14 electrically connected to the layer 12p.

(N-side electrode structure)
As shown in FIG. 1D, the n-side electrode structure 13 is provided on the n-side translucent electrode 131 provided on the n-side semiconductor layer 12 n in the first exposed portion 12 b and the n-side translucent electrode 131. N pad electrode 132 and external connection electrode 18 n provided on n pad electrode 132.

As shown in FIG. 1A, FIG. 1B, and FIG. 1D, the n-side electrode structure 13 has the 1st exposed part 12b and the discrete arrangement | positioning part 13a arrange | positioned discretely for every vicinity area | region. Each discrete arrangement portion 13 a is composed of an n-side translucent electrode 131 and an n-pad electrode 132. The n-side translucent electrode 131, the n-pad electrode 132, the opening 16n of the light reflecting film 16 and the opening 17n of the second insulating film 17 to be described later are each circular outer shapes of the first exposed portions 12b in a top view. And so as to be substantially concentric.
Further, the n pad electrode 132 of each discrete arrangement portion 13a is electrically connected to the external connection electrode 18n.

(N-side translucent electrode)
The n-side translucent electrode 131 is discretely provided for each first exposed portion 12b, as shown by hatching in the right-down oblique line in FIG. 2C. The n-side translucent electrode 131 is provided in ohmic contact with the upper surface of the n-side semiconductor layer 12n in each first exposed portion 12b. As shown in FIGS. 1C, 1D, and 2D, the n-side translucent electrode 131 is continuously covered with the surface of the semiconductor stacked body 12 by the insulating light reflecting film 16. In addition, an opening 16n of the light reflecting film 16 is provided for each discrete arrangement portion 13a above the n-side translucent electrode 131.
Note that the n-pad electrode 132 and the n-side semiconductor layer 12n may be directly in ohmic contact without providing the n-side translucent electrode 131.

  The n-side translucent electrode 131 is formed from a conductive metal oxide. Examples of the conductive metal oxide include an oxide containing at least one element selected from the group consisting of Zn, In, Sn, Ga, and Ti. In particular, ITO is preferably used because it is a material having high translucency with respect to visible light and high electrical conductivity.

(N-pad electrode)
The n pad electrodes 132 are provided discretely for each of the first exposed portions 12b, as shown by hatching in the right-down oblique line in FIG. 2E. The n pad electrode 132 is provided in the first exposed portion 12b and in the vicinity thereof. The n pad electrode 132 is provided so as to be electrically connected to the n-side translucent electrode 131 in the opening 16 n of the light reflecting film 16. The n-pad electrode 132 is further provided so as to extend to the p-side semiconductor layer 12p, which is outside the first exposed portion 12b, via the insulating light reflecting film 16.
The n pad electrode 132 is continuously covered with the upper surface of the light reflecting film 16 by the second insulating film 17, but, as shown in FIGS. 1C, 1D, and 2F, the n pad electrode 132 is provided for each discrete arrangement portion 13a. An opening 17 n of the second insulating film 17 is provided at a position on the upper surface of the electrode 132.

  The n-pad electrode 132 may be made of a metal having good light reflectivity, particularly Ag or an alloy thereof, in order to efficiently reflect light irradiated from the semiconductor stacked body 12 side to the semiconductor stacked body 12 side. The n-pad electrode 132 may have a laminated structure. For example, a light reflecting layer using a light reflecting material such as Ag or an alloy thereof is provided on the lower layer side, and the light reflecting layer is used on the upper layer side. A barrier layer for suppressing migration of the metal material, for example, a Ni layer or a Ti layer may be provided.

(N-side external connection electrode)
The external connection electrode 18n is an n-side terminal of the light-emitting element 1 for connection to an external power source. As shown in FIG. It is arranged in a horizontally long rectangular shape on the upper part and the lower part. Further, the external connection electrode 18n is connected at the right end of the middle step portion at the upper step portion and the lower step portion, and has an inverted C-shaped top view as a whole.
The external connection electrode 18n is provided on the second insulating film 17, and is electrically connected to the n pad electrode 132 of each discrete arrangement portion 13a in the opening 17n provided for each n-side discrete arrangement portion 13a. It is connected to the.

  A metal such as Cu, Au, or Ni can be used as the external connection electrode 18n. Further, the external connection electrode 18n may have a laminated structure using a plurality of types of metals. The external connection electrode 18n is preferably formed of at least the uppermost layer of Au in order to prevent corrosion and enhance the bonding property with a mounting substrate using an Au alloy-based adhesive member such as Au—Sn eutectic solder.

(P-side electrode structure)
As shown in FIG. 1E, the p-side electrode structure 14 includes a first insulating film 15 discretely provided on the p-side semiconductor layer 12p, an upper surface of each first insulating film 15, and an upper surface of the p-side semiconductor layer 12p. The p-side translucent electrode 141 provided so as to continuously cover the p-side translucent electrode 141, the p-pad electrode 142 provided on the p-side translucent electrode 141, and the external connection electrode 18p provided on the p-pad electrode 142 And is composed of.

As shown in FIG. 1A, the p-side electrode structure 14 has a plurality of discrete arrangement portions 14a on the upper surface side of the p-side semiconductor layer 12p. The plurality of discrete arrangement portions 14a are arranged so as to be two-dimensionally arranged squarely over substantially the entire surface excluding the region where the first exposed portion 12b is provided and the vicinity thereof. As shown in FIGS. 1B, 1C, and 1E, each discrete arrangement portion 14a includes a first insulating film 15 and a p-side translucent electrode 141. The first insulating film 15, the p-side translucent electrode 141, and the opening 16p of the light reflecting film 16 to be described later are provided so as to be substantially concentric when viewed from above.
In addition, the p-side translucent electrode 141 of each discrete arrangement portion 14a is electrically connected to a p-pad electrode 142 provided so as to cover substantially the entire upper surface of the p-side semiconductor layer 12p. Further, an external connection electrode 18 p is provided on a part of the upper surface of the p pad electrode 142.

Each discrete arrangement portion 14a is provided in a substantially circular shape when viewed from above, and is provided with two sizes having different diameters. As for the discrete arrangement | positioning part 14a, the thing of a small diameter is arrange | positioned in the arrangement | positioning position where space is restrict | limited like the case where the 1st exposed part 12b is provided in the vicinity.
In addition, although details will be described later, the discrete arrangement portion 14a has the same laminated structure, with the small diameter and the large diameter only having different sizes in a top view.

(First insulation film)
As shown by dot hatching in FIG. 2B, the first insulating films 15 are discretely arranged so as to be arranged in a two-dimensional square over substantially the entire surface of the p-side semiconductor layer 12p. Each first insulating film 15 has a substantially circular shape when viewed from the top, and as shown in FIG. 1C, is a region where the p-side translucent electrode 141 is disposed above and is p-side translucent. The electrode 141 and the p-pad electrode 142 are provided in a region where the opening 16p of the light reflecting film 16 is a region where the electrode 141 and the p-pad electrode 142 are in contact. Providing the first insulating film 15 between the p-side semiconductor layer 12p and the p-side translucent electrode 141 makes it difficult for current to flow through the p-side semiconductor layer 12p in the region immediately below the first insulating film 15. The light emission at is suppressed. Then, by reducing the amount of light that propagates toward the lower surface of the p-pad electrode 142, the amount of light absorbed by the p-pad electrode 142 that is a metal film can be reduced.
The first insulating film 15 is provided in the same region as the opening 16p when viewed from above, but may be provided in a wider range than the opening 16p so as to include the opening 16p.

  The first insulating film 15 preferably has translucency, and more preferably has a refractive index lower than that of the p-side semiconductor layer 12p and a large difference in refractive index from the p-side semiconductor layer 12p. Accordingly, the light propagating upward in the semiconductor stacked body 12 can be effectively reflected at the interface between the p-side semiconductor layer 12p and the first insulating film 15 based on the refractive index difference and Snell's law. it can. As a result, light absorption by the p pad electrode 142 can be further reduced.

As the first insulating film 15, at least one oxide or nitride selected from the group consisting of Si, Ti, Zr, Nb, Ta, and Al can be used. In particular, it is preferable to use SiO ₂ having a low refractive index and excellent translucency.

(P-side translucent electrode)
The p-side translucent electrode 141 is formed by continuously connecting the upper surface of the first insulating film 15 and the upper surface of the p-side semiconductor layer 12p for each of the discrete arrangement portions 14a, as shown by hatching in a right-upward oblique line in FIG. 2C. It is provided so that it may coat. The p-side translucent electrode 141 is covered with the insulating light reflecting film 16 so as to have an opening 16p in the upper surface of the first insulating film 15 in a top view. ing. Further, the p pad electrode 142 is provided in the opening 16 p of the light reflecting film 16 so as to be electrically connected to the upper surface of the p-side translucent electrode 141.

  The p-side translucent electrode 141 is provided in ohmic contact with the p-side semiconductor layer 12p. Although the p-side translucent electrode 141 is discretely arranged, the p-side translucent electrode 141 is arranged over substantially the entire upper surface of the p-side semiconductor layer 12p, so that the p-side translucent electrode 141 is interposed via the p-pad electrode 142. Can be diffused throughout the p-side semiconductor layer 12p. A first insulating film 15 is provided in a region immediately below a region where the p-side translucent electrode 141 is in contact with the p-pad electrode 142, and is configured so that current does not easily flow through the region.

The p-side translucent electrode 141 may be disposed so as to continuously cover substantially the entire upper surface of the p-side semiconductor layer 12p. However, as in the present embodiment, the p-side translucent electrode 141 is disposed. It is preferable to reduce the area to be used. In the region where the p-side translucent electrode 141 is not disposed, the light from the p-side semiconductor layer 12p is efficiently reflected by the light reflecting film 16 toward the semiconductor laminate 12 without passing through the p-side translucent electrode 141. Can be made. Therefore, by reducing the arrangement area of the p-side translucent electrode 141, light absorption by the p-side translucent electrode 141 can be reduced, and as a result, the light extraction efficiency of the light-emitting element 1 is increased. Can do.
The p-side translucent electrode 141 can be made of the same material as the n-side translucent electrode 131, such as ITO.

(P pad electrode)
The p-pad electrode (p-electrode) 142 has an opening 142a in the region where the first exposed portion 12b is provided and in the vicinity thereof, as shown in FIG. The semiconductor layer 12 p is provided so as to cover substantially the entire upper surface side of the semiconductor layer 12 p with the light reflecting film 16 interposed therebetween. The p-pad electrode 142 is electrically connected to the p-side translucent electrode 141 in the opening 16p of the light reflecting film 16 provided for each discrete arrangement portion 14a.
Further, the upper surface of the p pad electrode 142 is covered with the second insulating film 17 so as to have an opening 17p in a middle region when viewed from above. The p pad electrode 142 is electrically connected to the external connection electrode 18p in the opening 17p.
Note that the p-pad electrode 142 can be made of the same material as that of the n-pad electrode 132 described above, and may have a stacked structure similar to that of the n-pad electrode 132.

(P-side external connection electrode)
The external connection electrode 18p is a p-side terminal of the light-emitting element 1 for connection to an external power source. As shown in FIG. It is arranged in a rectangular shape.
The external connection electrode 18p is provided on the second insulating film 17, and is electrically connected to the p pad electrode 142 in the opening 17p of the second insulating film 17.
The p-side external connection electrode 18p can be made of the same material as the n-side external connection electrode 18n.

(Light reflecting film)
The light reflecting film 16 is provided so as to cover substantially the entire upper surface of the semiconductor stacked body 12 as shown by dot hatching in FIG. 2D. As shown in FIGS. 1D and 1E, the light reflecting film 16 is a dielectric formed by alternately laminating first dielectric layers 161 and second dielectric layers 162 which are two types of dielectric layers having different refractive indexes. Body multilayer film. More specifically, the dielectric multilayer film constitutes a DBR film.
By providing the DBR film as the light reflecting film 16, the light from the semiconductor stacked body 12 can be reflected to the lower surface side, which is the light extraction surface, with a higher light reflectivity than when a metal film is simply provided. As a result, the light extraction efficiency of the light emitting element 1 can be increased.
Further, most of the upper surface of the light reflecting film 16 that is an insulating film is covered with an n pad electrode 132 or a p pad electrode 142 that is a metal film, and is combined with the light reflecting film 16 that is a DBR film. Higher light reflectance can be obtained.

The light reflecting film 16 is provided on the upper layer side of the n-side translucent electrode 131 and the p-side translucent electrode 141, and an opening 16n is formed on the upper surface of the n-side translucent electrode 131 for each discrete arrangement portion 13a. And an opening 16p on the upper surface of the p-side translucent electrode 141 for each discrete arrangement portion 14a. In addition, the n-side translucent electrode 131 and the n-pad electrode 132 are electrically connected in the opening 16n, and the p-side translucent electrode 141 and the p-pad electrode 142 are electrically connected in the opening 16p.
In the region where the n-side translucent electrode 131 and the p-side translucent electrode 141 are not provided, the light reflecting film 16 is provided so as to be in contact with the semiconductor stacked body 12. For this reason, the light from the semiconductor stacked body 12 can be efficiently reflected and returned to the semiconductor stacked body 12 side.

The openings 16n and 16p are formed by dry etching using an etching mask after forming a dielectric laminated film in which the first dielectric layers 161 and the second dielectric layers 162 are alternately laminated (see FIG. 6A). Can be formed (see FIG. 6B). At this time, since the etching rate becomes slower toward the center of the openings 16n and 16p in a top view, as shown in FIG. 6B, the end surface of the formed opening 16p (the same applies to the opening 16n) is widened upward. It becomes an inclined inclined surface.
For this reason, in the light reflection film 16, the number of stacked first dielectric layers 161 and second dielectric layers 162 is partially reduced in the vicinity of the openings 16n and 16p. If the number of laminated DBR films is small, a sufficiently high light reflectance cannot be obtained. Accordingly, the light reflecting film 16 has a light reflectance lower than that of the other regions in the vicinity of the openings 16n and 16p.

Here, as shown in FIGS. 1D and 1E, in the light reflecting film 16, a region where the number of stacked dielectric multilayer films is not reduced is defined as a first portion 16a, which is a region near the openings 16n and 16p. A region on the side translucent electrode 131 and the p-side translucent electrode 141 is defined as a second portion 16b.
In the present embodiment, the light reflecting film 16 is configured to replace the first dielectric layer 161 in the second portion 16b with the air layer 163. Since air has a lower refractive index than the solid layer constituting the first dielectric layer 161, the DBR film in which the first dielectric layer 161 on the low refractive index side is replaced with the air layer 163 is used as the DBR film. And a higher light reflectivity than a DBR film made of the second dielectric layer 162. Therefore, in the second portion 16b, it is possible to reduce a decrease in light reflectivity due to a partial decrease in the number of laminated dielectric multilayer films.

  Although details of the manufacturing method will be described later, after the openings 16n and 16p are formed in the dielectric multilayer film, the end surfaces of the openings 16n and 16p of the light reflecting film 16 are side-etched by wet etching to form the first dielectric. By selectively removing the layer 161 (see FIG. 6C), the air layer 163 can be formed in the second portion 16b.

Further, it is preferable that the first dielectric layer 161 serving as the lowermost layer of the DBR film that is the light reflecting film 16 is configured to have a refractive index lower than that of the second dielectric layer 162. Furthermore, it is preferable that the first dielectric layer 161 has a refractive index lower than that of the semiconductor stacked body 12.
In particular, when a semiconductor having a relatively high refractive index (2.47), such as a nitride semiconductor, for example, GaN, is used as the semiconductor laminate 12, the first dielectric layer 161 of the semiconductor laminate 12 and the light reflecting film 16 is used. The difference in refractive index between the semiconductor stacked body 12 and the first dielectric layer 161 becomes large at the interface between the two. For this reason, the light reflectance at the interface based on the refractive index difference can be increased, and total reflection at the interface based on Snell's law can be obtained. That is, the light reflecting film 16 can further increase the light reflectance at the interface.

  Further, when a material having a relatively high refractive index (2.04) such as ITO is used as the n-side translucent electrode 131 and the p-side translucent electrode 141, the refractive index is higher than that of the second dielectric layer 162. It is preferable that the first dielectric layer 161 having a lower layer be the lowermost layer, and the first dielectric layer 161 has a lower refractive index than the n-side translucent electrode 131 and the p-side translucent electrode 141. . Similar to the interface between the first dielectric layer 161 and the semiconductor stacked body 12 described above, also at the interface between the first dielectric layer 161 and each of the n-side translucent electrode 131 and the p-side translucent electrode 141, The light reflectance can be further increased.

  Further, in the second portion 16b, the first dielectric layer 161 is replaced with an air layer 163 having a lower refractive index, so that the light reflecting film 16 and the n-side translucent electrode 131 or the p-side translucent electrode 141 are used. The difference in refractive index at the interface with each of the above becomes larger. For this reason, the light reflectance in the said interface based on a refractive index difference and Snell's law can further be improved.

In addition, on the p-side semiconductor layer 12p, it is difficult for current to flow through the semiconductor stacked body 12 located in a region immediately below the first insulating film 15, and a p-side translucent electrode provided around the first insulating film 15 is provided. It becomes easy for a current to flow in a region where 141 and the semiconductor stacked body 12 are in contact with each other. Therefore, the active layer 12a immediately below the region where the p-side translucent electrode 141 and the semiconductor laminate 12 are in contact tends to emit strong light.
Therefore, in the vicinity of the end face of the opening 16p, a decrease in the light reflectance due to a decrease in the number of stacked DBR films, which are the light reflecting films 16, tends to affect the light extraction efficiency.
Accordingly, the first dielectric layer 161 in the second portion 16b in the vicinity of the end face of the opening 16p is replaced with the air layer 163 to compensate for at least part of the decrease in light reflectance, thereby reducing the decrease in light extraction efficiency. be able to.

  Further, the range in which the air layer 163 is provided is preferably within the second portion 12b. The air layer 163 can be easily formed by the above-described wet etching method by not providing the air layer 163 from the end surfaces of the openings 16n and 16p deeply. Further, by not providing the air layer 163 continuously over a wide range, the light reflecting film 16 can be made less likely to be damaged by an external impact or the like.

  The air layer 163 is not limited to being filled with air, but may be filled with a gas such as nitrogen gas or argon gas instead of air, and has a refractive index (about 1.0) equivalent to that of air. What is necessary is just to be comprised.

The light reflecting film 16 is configured by alternately laminating the first dielectric layer 161 and the second dielectric layer 162 having different refractive indexes to reflect light in a wavelength region centered on a predetermined wavelength with high efficiency. be able to. That is, when the wavelength of light emitted from the semiconductor stacked body 12 is λ ₀ , the refractive index of the first dielectric layer 161 is n ₁ , and the refractive index of the second dielectric layer 162 is n ₂ , The thicknesses of the first dielectric layer 161 and the second dielectric layer 162 are λ ₀ / (4n ₁ ) and λ ₀ / (4n ₂ ), respectively. As a result, light in a wavelength region centered on the wavelength λ ₀ can be reflected with high efficiency.

The light reflection film that is a DBR film can obtain a higher light reflectance as the number of stacked layers of the first dielectric layer 161 and the second dielectric layer 162 increases. More preferably, the number is 7 pairs or more. For example, as a dielectric, a combination of SiO ₂ (refractive index 1.47) and Nb ₂ O ₅ (refractive index 2.33) and the number of stacked layers is three pairs, so that theoretically, a predetermined wavelength is set. A light reflectance of 90% or more can be obtained in a wide wavelength region centering on (for example, 560 nm).

  The air layer 163 has the same thickness as the first dielectric layer 161 having a higher refractive index than air. For this reason, the DBR film including the air layer 163 shifts the wavelength at which the maximum light reflectance is obtained, but the DBR film can obtain a high reflectance in a wide wavelength region. Therefore, the DBR film including the air layer 163 can obtain higher light reflectance than the DBR film including the first dielectric layer 161 even for light having a predetermined wavelength.

The dielectric material used for the first dielectric layer 161 and the second dielectric layer 162 is at least one oxide or nitride selected from the group consisting of Si, Ti, Zr, Nb, Ta, and Al. Can do. The light reflecting film 16 can be formed as a first dielectric layer 161 and a second dielectric layer 162 by combining two materials having different refractive indexes from these materials. Examples of the combination of the two types of materials include SiO ₂ as a low refractive index material, and Nb ₂ O ₅ , TiO ₂ , ZrO ₂ , Ta ₂ O _{5 and the} like as a high refractive index material.
In addition, the etching rate for the dielectric material used for the first dielectric layer 161 and the dielectric material used for the second dielectric layer 162 is adjusted so that the first dielectric layer 161 can be selectively removed by wet etching. It is preferable to select a combination of materials having a large difference.

As a combination of dielectric materials having good translucency, large refractive index difference, and large difference in etching rate when BHF (buffered hydrofluoric acid) is used as an etching solution, for example, SiO ₂ and Nb ₂ O ₅ Can be mentioned.

  The dielectric multilayer film composed of the first dielectric layer 161 and the second dielectric layer 162 is formed by alternately stacking the above-described two types of dielectric materials by sputtering or vapor deposition. Can be formed.

(Second insulating film)
As shown in FIG. 2F with dot hatching, the second insulating film 17 covers substantially the entire upper surface side of the semiconductor stacked body 12 via the light reflecting film 16, the n pad electrode 132, and the p pad electrode 142. It is provided to do.
As shown in FIG. 1C, the second insulating film 17 is provided on the upper layer side of the light reflecting film 16, the n pad electrode 132, and the p pad electrode 142, and the upper surface of the n pad electrode 132 for each discrete arrangement portion 13a. Has a circular opening 17n. The second insulating film 17 has a horizontally elongated substantially rectangular opening 17p on the upper surface of the p-pad electrode 142 in the middle region when viewed from above. The n pad electrode 132 and the external connection electrode 18n are electrically connected in the opening 17n, and the p pad electrode 142 and the external connection electrode 18p are electrically connected in the opening 17p.

The second insulating film 17 can be formed using the same material as the first insulating film 15 described above. The second insulating film 17 is preferably made of a material having a good gas barrier property so that the n-pad electrode 132, the p-pad electrode 142, the semiconductor stacked body 12 and the like on the lower layer side can be protected from the outside air. For example, since SiN has higher water immersion resistance than SiO _2, it is possible to favorably suppress migration of Ag contained in the n pad electrode 132 and the p pad electrode 142 by using SiN for the second insulating film 17. it can.

The outer shape of the light-emitting element 1, the shape and location of the first exposed portion 12 b, the n-side translucent electrode 131 and the n-pad electrode 132, the number of arrangements, the location of the first insulating film 15 and the p-side translucent electrode 141 Further, the number of arrangement, the shape and arrangement location of the external connection electrodes 18n and 18p, and the like can be determined as appropriate.
In particular, the number of the discrete arrangement portions 13a and 14a is large. Therefore, as the number of the openings 16n and 16p of the light reflection film 16 is larger, more inclined side surfaces are formed in the light reflection film 16. For this reason, the 1st dielectric material layer 161 replaced with the air layer 163 increases, and the effect which improves a light reflectivity becomes large.

[Method for Manufacturing Light-Emitting Element]
Next, a method for manufacturing the light-emitting element 1 according to the embodiment will be described with reference to FIGS. 3 to 9 (refer to FIGS. 2A to 2G as appropriate).
4A to 5 and 7 to 9 show cross sections at positions corresponding to the IC-IC line in FIG. 1B. 6A to 6C show a cross section at a position corresponding to FIG. 1E.

As shown in FIG. 3, the manufacturing method of the light-emitting element 1 includes a semiconductor laminate preparation step S10, a light reflection film formation step S20, a pad electrode formation step S30, a second insulating film formation step S40, and an external connection. It includes an electrode forming step S50 and an individualization step S60, and each step is performed in this order.
Further, the semiconductor stacked body preparation step S10 includes a semiconductor stacked body forming step S101, a first insulating film forming step S102, and a translucent electrode forming step S103. The light reflecting film forming step S20 includes a dielectric multilayer film forming step S201, an opening forming step S202, and a first dielectric layer removing step S203.

Each process is performed by a wafer level process in which a plurality of light emitting elements 1 are formed on one substrate 11. That is, the plurality of light emitting elements 1 are formed on the substrate 11 so as to be two-dimensionally arranged. 4A to 5 and FIGS. 7 to 9 show cross sections of a part of one light emitting element 1.
Hereinafter, each process will be described sequentially.

(Semiconductor laminated body preparation process (process which prepares a semiconductor laminated body))
In the semiconductor stacked body preparation step S10, the semiconductor stacked body 12 in which the n-side semiconductor layer 12n and the p-side semiconductor layer 12p are sequentially provided upward, and is provided on a part of the upper surface of the p-side semiconductor layer 12p. The semiconductor laminated body 12 provided with the translucent first insulating film 15 and the p-side translucent electrode 141 that covers the first insulating film 15 and is provided on the upper surface of the p-side semiconductor layer 12p. prepare.
More specifically, in the semiconductor stacked body preparation step S10, three steps described below are sequentially performed.

(Semiconductor laminate formation process)
First, in the semiconductor stacked body forming step S101, as shown in FIG. 4A, the semiconductor stacked body 12 having the first exposed portion 12b and the second exposed portion 12c (see FIG. 2A) is formed. The semiconductor stacked body 12 is formed by sequentially stacking an n-side semiconductor layer 12n, an active layer 12a, and a p-side semiconductor layer 12p on the upper surface of a substrate 11 made of sapphire or the like by using a nitride semiconductor or the like by an MOCVD method or the like. can get. Next, a region for forming the discrete arrangement portion 13a of the n-side electrode structure 13 and a boundary region (dicing street) that is a region along the boundary line BD that partitions the plurality of light emitting elements 1 are etched by an etching method or the like. A first exposed portion 12b and a second exposed portion 12c in which the n-side semiconductor layer 12n is exposed can be formed.

(First insulating film forming step)
Next, in the first insulating film forming step S102, as shown in FIG. 4B, the first insulating film 15 is formed in each region where the discrete arrangement portions 14a on the upper surface of the p-side semiconductor layer 12p are to be formed.
The first insulating film 15 can be formed by a sputtering method or the like using an insulating material such as SiO ₂ .

(Translucent electrode forming step)
Next, in the translucent electrode forming step S103, as shown in FIG. 4C, the n-side translucent electrode 131 that covers the upper surface of the n-side semiconductor layer 12n in the first exposed portion 12b, and each first insulating film 15 And a p-side translucent electrode 141 that continuously covers the upper surface of the p-side semiconductor layer 12p.
The n-side translucent electrode 131 and the p-side translucent electrode 141 can be simultaneously formed by a sputtering method or the like using a material having translucency and conductivity such as ITO. Further, after the film formation, heat treatment is performed so that the n-side translucent electrode 131 and the p-side translucent electrode 141 and the semiconductor stacked body 12 are in ohmic contact.

(Light reflecting film forming step (step of providing a light reflecting film))
Next, in the light reflecting film forming step S20, as shown in FIG. 5, a light reflecting film 16 that is a DBR film is formed. More specifically, in the light reflection film forming step S20, three steps described below are sequentially performed.

Hereinafter, with reference to FIGS. 6A to 6C, the formation of the light reflection film 16 provided in the p-side discrete arrangement portion 14 a will be described.
Although not shown, the opening 16n is formed on the upper surface of the n-side translucent electrode 131 on the n-side semiconductor layer 12n in the first exposed portion 12b by the same process as that on the p-side semiconductor layer 12p. The light reflecting film 16 is formed so as to have.

(Dielectric multilayer film formation process)
First, in the dielectric multilayer film forming step S201, two types of dielectric materials such as SiO ₂ and Nb ₂ O ₅ are alternately used and laminated with a predetermined film thickness by sputtering or the like, respectively. As shown to 6A, the light reflection film 16 which is a dielectric multilayer film which consists of the 1st dielectric material layer 161 and the 2nd dielectric material layer 162 is formed.

(Opening formation step (step of providing an opening in the light reflecting film))
Next, in the opening forming step S202, as shown in FIG. 6B, the mask M is formed so as to have an opening on the p-side translucent electrode 141 (and the n-side translucent electrode 131) by photolithography or the like. Form. Then, the opening 16p (and the opening 16n) is formed in the light reflecting film 16 by a dry etching method such as RIE (reactive ion etching) using the mask M as an etching mask. As described above, the end face of the opening 16p (and the opening 16n) formed by etching is formed so as to be inclined so that the opening becomes wider upward.

(First Dielectric Layer Removal Step (Step of Removing First Dielectric Layer))
Next, in the first dielectric layer removing step S203, as shown in FIG. 6C, the end surface of the opening 16p (and the opening 16n) of the light reflecting film 16 is side-etched by wet etching, thereby performing the first etching. The dielectric layer 161 is removed.
For example, when SiO ₂ is used for the first dielectric layer 161 and Nb ₂ O ₅ is used for the second dielectric layer 162, the first dielectric layer can be obtained by using BHF (buffered hydrofluoric acid) as an etchant. The difference in etching rate between 161 and the second dielectric layer 162 can be increased. Thereby, the first dielectric layer can be substantially selectively removed.
Etching proceeds in the lateral direction from the end face of the opening 16p, and the time and temperature of the wet etching are performed so that the first dielectric layer 161 in the second portion 16b, which is the region on the p-side translucent electrode 141, is removed. Adjust. The same applies to the light reflecting film 16 provided on the n-side translucent electrode 131.

  Note that the removal of the first dielectric layer 161 in the second portion 16b may not be as strict as schematically illustrated in FIG. 6C. For example, the first dielectric layer 161 disposed on the upper layer side may be removed up to a part of the first portion 16a, and the first dielectric layer 161 disposed on the lower layer side is one of the second portions 16b. The part may not be removed.

(Pad electrode formation process)
Next, in the pad electrode forming step S30, as shown in FIG. 7, the n pad electrode 132 is formed so as to cover the upper surface of the light reflecting film 16 in and near the opening 16n, and in the opening 16p and A p-pad electrode 142 is formed so as to cover substantially the entire surface above the p-side semiconductor layer 12p.
The n pad electrode 132 and the p pad electrode 142 can be formed using a metal material such as Ag by a sputtering method, an evaporation method, or the like.

(Second insulating film forming step)
Next, in the second insulating film forming step S40, as shown in FIG. 8, each n pad electrode 132 has an opening 17n, and a predetermined region on the p pad electrode 142 has an opening 17p. A second insulating film 17 is formed so as to cover the entire upper surface of the wafer.
The second insulating film 17 can be formed by a sputtering method or the like using an insulating material such as SiO ₂ .

(External connection electrode formation process)
Next, in the external connection electrode formation step S50, as shown in FIG. 9, external connection electrodes 18n and 18p are formed in predetermined regions on the second insulating film 17. The external connection electrode 18n is electrically connected to the n pad electrode 132 in each opening 17n, and the external connection electrode 18p is electrically connected to the p pad electrode 142 in the opening 17p.
The external connection electrodes 18n and 18p can be formed by a sputtering method, a vapor deposition method, a plating method, or the like using a metal material such as Au.

(Individualization process)
Next, in the singulation step S60, the wafer is singulated into a plurality of light emitting elements 1 by cutting by a dicing method or a scribing method along the boundary line set on the second exposed portion 12c. .

Note that the back surface of the substrate 11 may be polished and thinned before cutting the wafer. Further, a support member such as a resin may be provided on the upper surface side of the semiconductor stacked body 12, and the substrate 11 may be removed by an LLO (laser lift off) method or the like.
Further, a phosphor layer may be provided on the light extraction surface side of the light emitting element 1 to extract combined light obtained by synthesizing light from the light emitting element 1 and the phosphor layer.
The light emitting element 1 can be manufactured through the above steps.

  As mentioned above, although the light emitting element concerning this invention and its manufacturing method were concretely demonstrated by the form for inventing, the meaning of this invention is not limited to these description, Claim of a claim It must be interpreted widely based on the description. Needless to say, various changes and modifications based on these descriptions are also included in the spirit of the present invention.

  The light-emitting element manufactured by the light-emitting element according to the present invention and the manufacturing method thereof can be used for various light sources such as a backlight light source of a liquid crystal display, various lighting fixtures, and a large display.

DESCRIPTION OF SYMBOLS 1 Light emitting element 11 Board | substrate 12 Semiconductor laminated body 12n N side semiconductor layer 12a Active layer 12p P side semiconductor layer 12b 1st exposed part 12c 2nd exposed part 13 n side electrode structure 13a Discrete arrangement part 131 n side translucent electrode 132 n pad electrode 14 p side electrode structure 14a discrete arrangement portion 141 p side translucent electrode 142 p pad electrode 142a opening 15 first insulating film 16 light reflection film 161 first dielectric layer 162 second dielectric layer 163 air Layer 16a First part 16b Second part 16n, 16p Opening 17 Second insulating film 17n, 17p Opening 18n, 18p External connection electrode M Mask

Claims (6)

a semiconductor stacked body in which an n-side semiconductor layer and a p-side semiconductor layer are sequentially provided upward;
A translucent insulating film provided on a part of the upper surface of the p-side semiconductor layer;
A p-side translucent electrode that covers the insulating film and is provided on an upper surface of the p-side semiconductor layer;
A light reflecting film covering the semiconductor laminate and the p-side translucent electrode, and having an opening in a part above the p-side translucent electrode;
A p-electrode electrically connected to the p-side translucent electrode through the opening,
The light reflecting film is a DBR film, and is located above the semiconductor stacked body and in a region where the p-side transmissive electrode is not provided, and above the p-side transmissive electrode. A second part located at
The first portion is formed by alternately laminating the first dielectric layer and the second dielectric layer having a higher refractive index than the first dielectric layer, with the lowermost layer as the first dielectric layer.
The second portion has the lowermost layer as an air layer, and the air layer and the second dielectric layer are alternately stacked ,
The end face of the opening is inclined so that the opening becomes wider upward.
The light emitting element in which the number of stacked light reflecting films in the second part is smaller than the number of stacked light reflecting films in the first part . 2. The light emitting device according to claim 1 , wherein the semiconductor stacked body is made of a nitride semiconductor represented by In _X Al _Y Ga _1-XY N (0 ≦ X, 0 ≦ Y, X + Y <1). The light emitting device according to claim 1, wherein the p-side translucent electrode is ITO (indium tin oxide). Said first dielectric layer, the light emitting device according to any one of claims 1 to 3 is SiO _2. Said second dielectric layer, the light emitting device according to any one of claims 1 to 4 is a Nb ₂ O _5. A semiconductor stacked body in which an n-side semiconductor layer and a p-side semiconductor layer are sequentially provided upward, a light-transmitting insulating film provided on a part of an upper surface of the p-side semiconductor layer, and the insulation Providing the semiconductor laminate including a film and a p-side translucent electrode provided on an upper surface of the p-side semiconductor layer; and
The first dielectric layer and the second dielectric layer having a refractive index higher than that of the first dielectric layer are alternately laminated above the semiconductor laminate, with the lowermost layer being the first dielectric layer. Providing a light reflecting film;
Providing a portion of the upper part of the p-side translucent electrode by a dry etching method so that the light reflection film has an opening that is inclined so that the opening is wider upward ;
Removing the first dielectric layer in a region where the p-side translucent electrode is disposed when viewed from the upper surface side by wet-etching the end surface of the opening , and
The light reflecting film is a DBR film, and is located above the semiconductor stacked body and in a region where the p-side transmissive electrode is not provided, and above the p-side transmissive electrode. A second part located at
The first portion is formed by alternately laminating the first dielectric layer and the second dielectric layer having a refractive index higher than that of the first dielectric layer, with the lowermost layer being the first dielectric layer. Become
The second portion has the lowermost layer as an air layer, and the air layer and the second dielectric layer are alternately stacked,
The method of manufacturing a light emitting device , wherein the number of stacked light reflecting films in the second part is smaller than the number of stacked light reflecting films in the first part .

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