JP2012227234A - Light-emitting device, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device capable of splitting at an intended position with accuracy without meandering of a splitting line by utilizing an altered layer by laser irradiation and a dicing groove in splitting, and of improving an optical output of the light-emitting element with ease and certainty by utilizing a recessed part caused by the dicing groove of the obtained light-emitting element, and to provide a method of manufacturing the same.SOLUTION: A light-emitting device has: a light-emitting element having a semiconductor layer laminated on a first principal surface of a sapphire substrate having the first principal surface and a second principal surface; a package to which the second principal surface of the sapphire substrate is bonded, and on which the light-emitting element is mounted; and an encapsulation member containing a phosphor, and encapsulating the light-emitting element. In the sapphire substrate, an outer edge of the second principal surface is located inside an outer edge of the first principal surface. The sapphire substrate has a recessed part formed by one curve surface of the sapphire substrate and the package. The phosphor is arranged in the recessed part.

Description

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

Conventionally, in order to cleave a sapphire wafer on which a semiconductor layer is laminated, a dicing groove is formed on the lower surface of the sapphire wafer with a dicer, and a scribe line is formed in the dicing groove using a scriber. A method of applying a load such as a roller to a scribe line has been proposed (for example, Patent Document 1).
In addition, a method has been proposed in which after an altered layer is formed inside a wafer such as silicon with a laser scriber, a groove is formed on the back surface of the wafer with a cutting blade and then fractured (for example, Patent Documents 2 and 3).
In these methods, breaking at the cutting groove is required to obtain a chip.
However, a sapphire wafer generally used for a light emitting element is very hard unlike silicon or the like, and it is actually difficult to form a uniform dicing groove at a considerable depth. In addition, even if the scribe groove is formed from the back side of the wafer, it is extremely difficult to fit the breaking of the laminated structure of the wafer and the semiconductor layer along the scribe groove only in the intended portion. It causes a situation where cracks or chipping occurs.
In addition, when a laser scriber is used, there is a problem in that a light output is reduced due to debris generated when the wafer is vaporized.

JP-A-8-274371 JP 2008-227276 A JP 2009-206162 A

When manufacturing a light-emitting element from a laminate of nitride semiconductor layers using a sapphire substrate, even if it is actually cleaved using a known method, it cannot be cleaved with high precision at the intended site. However, the present situation is that chipping and cracking of the semiconductor layer occur and it is impossible to prevent the yield from decreasing.
In particular, when a laser scriber is used, the light output of the obtained light emitting element is also reduced.

  The present invention has been made in order to solve the above-described problems. When a sapphire wafer is cleaved, an alteration layer and a dicing groove formed by laser irradiation are used so that the cleaving line does not meander and an intended portion. And a light emitting device capable of improving the light output of the light emitting element easily and reliably by using the recess due to the dicing groove on the back surface of the sapphire wafer of the obtained light emitting element It is an object of the present invention to provide a method for manufacturing a light emitting device.

A light emitting device of the present invention includes a semiconductor layer laminated on the first main surface of a sapphire substrate having a first main surface and a second main surface,
A light-emitting device including a package on which the second main surface of the sapphire substrate is bonded and the light-emitting element is placed; a phosphor; and a sealing member that seals the light-emitting element;
(1) The sapphire substrate has an outer edge of the second main surface located on an inner side of the outer edge of the first main surface, and has a concave portion formed by one curved surface of the sapphire substrate and the package. The phosphor is disposed in the recess,
(2) The sapphire substrate has an outer edge of the second main surface positioned on an inner side of the outer edge of the first main surface, and has a recess formed by one plane of the sapphire substrate and the package. The phosphor is disposed in the recess.
In these light emitting devices,
It is preferable that the said recessed part is located in the outer edge of the said 2nd main surface of the said sapphire substrate.
The recess preferably has a depth within half of the thickness of the sapphire substrate from the second main surface of the sapphire substrate.
It is preferable that the width of the concave portion is gradually changed from the first main surface side to the second main surface side of the sapphire substrate.

In the method for manufacturing a light emitting device of the present invention,
A semiconductor layer is laminated on the first main surface of the sapphire wafer,
Irradiating laser into the sapphire wafer from the second main surface side of the sapphire wafer to form an altered layer for cleaving,
Forming a dicing groove at a position corresponding to the second main surface and the altered layer of the sapphire wafer, and removing the altered layer;
The method includes cleaving the sapphire wafer and the semiconductor layer to form a light emitting element.

ADVANTAGE OF THE INVENTION According to this invention, the light-emitting device which improved the light output of the light emitting element simply and reliably can be provided by utilizing the recessed part resulting from the dicing groove in the sapphire wafer back surface of a light emitting element.
Further, when the sapphire wafer is cleaved, by using the altered layer and the dicing groove by laser irradiation, the cleaving line does not meander and can be cleaved accurately at the intended site, and the yield can be improved. A method for manufacturing a light-emitting device can be provided.

It is a top view for demonstrating the structure of the light-emitting device of this invention. It is a schematic sectional drawing of the light emitting element vicinity in the C-C 'line cross section of the light-emitting device of FIG. 1A. It is a top view sectional drawing for demonstrating the structure of the light emitting element mounted in the light-emitting device of this invention. It is a schematic sectional drawing of the A-A 'line | wire of FIG. 2A. It is a schematic sectional drawing for demonstrating the structure of another light emitting element mounted in the light-emitting device of this invention. It is a graph which shows the light distribution of a light emitting element about the structure of the light-emitting device of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a semiconductor light emitting element for embodying the technical idea of the present invention, and the present invention does not specify the semiconductor 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.

(Light emitting device)
For example, as illustrated in FIG. 1A, the light emitting device 1 of the present invention is configured by mounting a light emitting element 10 on a package and sealing the surface of the light emitting element 10 with a sealing member 2.

(Light emitting element)
As shown in FIG. 2A, the light-emitting element 10 mounted on the light-emitting device 1 of the present invention includes a first layer on a sapphire substrate 11 and one or more layers (not shown) such as a buffer layer. A semiconductor layer 15 is formed by laminating a conductive type (hereinafter sometimes referred to as “n-type”) semiconductor layer 12, a light emitting layer 13, and a second conductive type (hereinafter also referred to as “p-type”) semiconductor layer 14 in this order. ing. The semiconductor layer 15 is partially removed, from which the n-type semiconductor layer 12 is exposed. Hereinafter, the laminated surface of the semiconductor layer 15 of the sapphire substrate 11 may be referred to as “surface 11a” or “first main surface”.
On the exposed n-type semiconductor layer 12 and the second conductive semiconductor layer 14, an n-side electrode 16 and a p-side electrode 17 are formed on substantially the entire surface of the semiconductor layers, respectively. A pad electrode 18 is formed on the p-side electrode 17.
A protective film (not shown) is formed on the surface of the light emitting element 10.
Note that the light-emitting element can emit light having various wavelengths depending on the composition of the semiconductor layer. For example, in the present invention, a light-emitting element that emits blue light (wavelength of about 380 to 480 nm) is preferable from the viewpoint that it is possible to further improve the light output.
When the light emitting element 10 is mounted on a package, the surface of the sapphire substrate opposite to the stacked surface of the semiconductor layers 15 (hereinafter referred to as “rear surface 11 b” or so on) “Sometimes referred to as“ second main surface ”) is disposed on the lower side.

As shown in FIG. 2B, the sapphire substrate 11 has a recess 20 formed on the side surface thereof on the back surface 11b side. The recess 20 is formed by the outer edge of the back surface 11b of the sapphire substrate 11 being located inside the outer edge of the surface 11a. Further, the recess 20 is formed by one plane 21 in the sapphire substrate 11 and a package described later. Further, as shown in FIG. 2C, the concave portion may be a single curved surface 31 in the sapphire substrate 11 and a concave portion 30 formed by a package described later.
If this recessed part 20 is located in the outer edge of a sapphire substrate, the depth and width will not be specifically limited, For example, the recessed part 20 is less than half the thickness of the sapphire substrate 11 from the back surface 11b of the sapphire substrate 11. It preferably has a depth D, and more preferably about 1/5 to half the thickness of the sapphire substrate 11. Specifically, about 20-90 micrometers is suitable and about 30-70 micrometers is preferable.
Moreover, it is suitable for the recessed part 20 to have the width W within the thickness (100%) of a sapphire substrate from the outer edge in the back surface 11b of a sapphire substrate, the width W within about 90% is preferable, and 30-90 A width W of about% is more preferable. Specifically, about 30 to 100 μm is suitable.
In general, the sapphire substrate 11 has a thickness of about 200 μm or less, for example, a thickness of about 100 to 180 μm in the light emitting element.
As long as the recess 20 has the depth D and the width W described above, the shape and the like are not particularly limited, but it is preferable that the width gradually changes from the front surface to the back surface of the sapphire substrate. In particular, it is preferable that the width gradually changes so that the front surface side is small and the back surface side is large. Here, “gradual” means that it is gradually changing, and it is preferable that the change is not a sudden change, that is, a change that suddenly enters in a substantially vertical direction with respect to the front and back surfaces of the sapphire substrate.
The recess 30 is the same as described above.
The concave portion 20 and the concave portion 30 are, for example, a tapered shape (a plane 21 in FIG. 2B) having an inclination angle of about 45 to 75 ° with respect to the front and back surfaces of the sapphire substrate, or a curved surface 31 whose tangent is about 45 to 75 °. 2C) and the like are preferable. This avoids the attenuation due to the reflection of light on the back surface side of the sapphire substrate due to the change that suddenly enters the front and back surfaces of the sapphire substrate as described above. Can do. In addition, a part of the light emitted from the light emitting element and entering the sapphire substrate is reflected by this inclination, so that the extraction of light from the inclined part can be increased along with the extraction of light in the front direction. Moreover, by adjusting to such an inclination range, the number of reflections of the light which penetrate | invaded sapphire can be reduced, and it can reflect in a front direction efficiently. A curved surface is preferable because the light extraction efficiency is further improved.

Usually, since the planar shape of the light emitting element is a quadrangle or a substantially quadrangular shape, the concave portion only needs to be formed on two opposing surfaces, that is, formed on approximately half or more of the outer edge of the back surface of the sapphire substrate. What is necessary is just to be formed, and it is preferable that it forms in two sets of opposing surfaces. Furthermore, it is preferable that the sapphire substrate is formed on substantially the entire outer edge of the back surface. Since the concave portion is arranged in such a part in such a part, the phosphor is arranged in a part where light emitted from the light emitting layer is relatively concentrated by accommodating the fluorescent substance described later in the concave part. Therefore, more light can be extracted effectively.
One light-emitting element may be mounted on one light-emitting device, but two or more light-emitting elements may be mounted.

(package)
The package is formed by integrally forming a pair of metal members 3 that protect the light emitting element 10 and that function as terminals by being connected to the electrodes of the light emitting element 10. The recess 20 or the recess 30 described above is formed by a package, usually a metal member, and the sapphire substrate 11.
(Metal member)
The metal member is an electrode for electrically connecting to the light emitting element, and may be substantially plate-shaped, and may be corrugated plate-shaped or plate-shaped having irregularities. The material is not particularly limited, and it is preferably formed of a material having a relatively large thermal conductivity. By forming with such a material, heat generated in the light emitting element can be efficiently released. For example, a material having a thermal conductivity of about 200 W / (m · K) or more, a material having a relatively large mechanical strength, or a material that can be easily punched or etched is preferable. Specific examples include metals such as copper, aluminum, gold, silver, tungsten, iron and nickel, and alloys such as iron-nickel alloys and phosphor bronze.
Usually, two or more metal members are provided in one light emitting device, and it is appropriate that the number of light emitting elements is +1 or more, or more than twice the number of light emitting elements.
The material, shape, size, thickness, and the like of the metal member are not particularly limited, but it is necessary that the metal member be a material that can supply appropriate power to the light emitting element.

(resin)
The resin for forming the package may be any material as long as the metal member is integrally formed and insulation can be ensured with respect to the light emitting element and the metal member. For example, thermoplastic resin, thermosetting resin, etc., specifically, polyphthalamide (PPA), polycarbonate resin, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), ABS resin, epoxy resin, phenol resin, acrylic resin , Resin such as PBT resin, ceramic and the like. Moreover, you may mix and use various dyes or pigments for these materials as a coloring agent. Examples of the colorant include Cr ₂ O ₃ , MnO ₂ , Fe ₂ O ₃ , and carbon black.

  The size and shape of the package including the metal member are not particularly limited, and the outer shape in a plan view (out-plane shape) is usually a quadrangle, for example, a circle, an ellipse, a triangle, a polygon, Any shape such as a shape approximating these may be used. Of these, a rectangular shape extending in the longitudinal direction is preferable.

An opening 4 a is formed on the surface of the package, the metal member 3 is exposed on the bottom surface of the opening 4 a, and the light emitting element 10 is mounted on the metal member 3. That is, the sapphire substrate of the light emitting element is connected to the metal member. Thereby, the heat generated in the light emitting element can be released to the metal member.
The light emitting elements are usually connected via a joining member. For example, in the case of a light emitting element having blue and green light emission and using a sapphire substrate, an epoxy resin, silicone, or the like can be used. In consideration of deterioration from light and heat from the light emitting element, the back surface of the light emitting element may be plated with Al, without using resin, solder such as Au—Sn eutectic, low melting point metal, etc. A material may be used.

(Sealing member)
For example, as shown in FIG. 1B, the surface of the light emitting element is usually sealed with a sealing member 2. The sealing member 2 can protect the light emitting element 10 from external force, moisture, and the like, and also protects the wire. Moreover, the fluorescent substance 2b can be contained and the light radiate | emitted from the light emitting element 10 can be converted into a predetermined wavelength.
Therefore, the sealing member 2 is not particularly limited as long as it transmits light emitted from the light emitting element and contains the phosphor 2b, and a known member in the field can be used. Can do.

  Examples of the sealing member include transparent resin or glass having excellent weather resistance such as epoxy resin, silicone resin, acrylic resin, and urea resin. In particular, even when transparent resin contains moisture in the translucent coating material during the process or during storage, the moisture contained in the resin is removed from the outside air by baking at 100 ° C. for 14 hours or more. It is possible to prevent water vapor explosion and peeling of the light emitting element and the mold member.

The phosphor contained in the sealing member converts the wavelength of light emitted from the light emitting element to the outside of the package. When the light from the light-emitting element is high-energy short-wavelength visible light, nitrogen-containing CaO—Al ₂ O activated with an organic phosphor, a perylene derivative, ZnCdS: Cu, YAG: Ce, Eu and / or Cr Various phosphors such as an inorganic phosphor such as _3- SiO ₂ can be used.
In the light-emitting device of the present invention, in particular, by using a YAG: Ce phosphor, light from a light-emitting element that emits blue light and yellow light that partially absorbs the light to obtain a complementary color are obtained. Thus, white light can be obtained with high reliability. In addition, when a nitrogen-containing CaO—Al ₂ O ₃ —SiO ₂ phosphor activated with Eu and / or Cr is used, blue light and red light that partially absorbs the light and becomes complementary color are generated. Thus, white light can be obtained with high reliability. In particular, due to the concave shape of the sapphire substrate of the light emitting device of the present invention, the most improved light extraction has been confirmed in white light. In addition, the phosphor is completely settled to remove bubbles, and the color unevenness can be further reduced by arranging the phosphor with a high concentration in the recess.
In addition, it is suitable that the phosphor is contained in about 15 to 20% of the total weight of the sealing member.

The sealing member 2 contains the phosphor 2b uniformly or unevenly distributed, but as shown in FIG. 1B, the phosphor 2b is disposed in the vicinity of the surface of the light emitting element 10 and / or the recess 20. . In particular, the sealing member 2 containing the phosphor is disposed so that the phosphor 2b is disposed in the recess 20 formed on the metal member side surface (back surface) of the side surface of the sapphire substrate of the light emitting element. As described above, by arranging the phosphor on the back surface side of the sapphire substrate, it is possible to minimize the light absorption of the conventional light on the sapphire substrate and to arrange the phosphor in a portion where light is relatively concentrated. Therefore, the emitted light can be further wavelength-converted by the phosphor and taken out, and the light output can be improved.
In the conventional light, part of the light emitted from the light emitting layer passes through the sapphire substrate toward the back surface of the sapphire substrate, is reflected by the surface of the metal member, and passes through the sapphire substrate again. As a result, the light emitted from the light emitting layer is more absorbed by passing through the sapphire substrate and exposed to a factor that reduces the light extraction efficiency.
On the other hand, by providing a recess on the back side of the sapphire substrate and arranging a phosphor inside the sapphire substrate, a part of the light emitted from the light emitting layer and directed to the back surface of the sapphire substrate is reflected on the metal member due to the presence of the recess. And can be easily taken out to the outside. Further, the change in the light wavelength can be further improved by positively absorbing the light extracted to the outside from the vicinity of the concave portion, which is a relatively light-concentrating portion.

  The sealing member may contain a diffusing agent. The diffusing agent diffuses light and can reduce the directivity from the light emitting element and increase the viewing angle. Examples of the light diffusing agent include calcium carbonate, aluminum oxide, and titanium oxide.

(Method for manufacturing light emitting device)
In the method for manufacturing a light emitting device of the present invention, a sapphire wafer is first prepared in order to manufacture the above-described light emitting device. Any commercially available sapphire wafer can be used. In particular, those having a hexagonal crystal structure are preferred. Moreover, what has an oriental flat and the 1st main surface (surface) of a sapphire wafer is a C surface is preferable. By using such a sapphire wafer, the sapphire wafer can be cleaved with high precision in the intended direction by laser irradiation and groove formation to be described later.

On the 1st main surface (surface) of a sapphire wafer, a 1st conductivity type semiconductor layer, a light emitting layer, and a 2nd conductivity type semiconductor layer are laminated in this order, and a semiconductor layer is formed. The semiconductor layer can be formed by appropriately adjusting conditions and the like by a method usually used in this field.
For example, the semiconductor layer can be formed by a known technique such as MOVPE, metal organic chemical vapor deposition (MOCVD), hydride vapor deposition (HVPE), molecular beam epitaxial growth (MBE), or the like.

  Next, a laser-irradiated laser beam is irradiated into the sapphire wafer from the second main surface (back surface) side of the sapphire wafer to form an altered layer for cleaving. As the laser, for example, a femtosecond laser, a picosecond laser, a nanosecond laser, a stealth laser, or the like is preferably used, and a femtosecond laser is more preferable. These lasers can oscillate by compressing the laser pulse width to femtoseconds / picosecond units or the like, and usually emit light having a wavelength of about several hundred to 1,000 nm, for example, about 800 nm. Things. By using such a laser, the altered layer can be formed efficiently only in the intended portion, not in the surface of the sapphire wafer but in the thickness direction.

  Laser irradiation may be performed only at a certain depth from the back surface of the sapphire wafer, but in the depth direction in consideration of the thickness of the sapphire wafer, the size of the altered layer, the power of the laser to be irradiated, etc. You may carry out in two places, three places, or more by changing a position. Although the deteriorated layer is formed by such laser irradiation, the position is preferably unevenly distributed on the back surface side of the sapphire wafer rather than the depth of the dicing groove in the subsequent step. Thereby, the altered layer can be completely removed from the sapphire wafer by dicing for forming a groove in a later step, and reflection / absorption of light at the altered layer can be prevented.

For example, when the thickness of the sapphire wafer at the time of laser irradiation is about 100 to 180 μm and the depth of the groove in the subsequent process is 30 to 40 μm, about 40 to 20 μm (for example, 30 μm) from the back surface of the sapphire wafer; The laser irradiation may be performed in two stages to a depth of about 35 to 15 μm (for example, 25 μm). When the groove depth is 40 to 60 μm, the back surface of the sapphire wafer is 90 to 70 μm (for example, 80 μm). ), About 64 to 45 μm (for example, 55 μm) and about 40 to 20 μm (for example, 30 μm), and laser irradiation in three stages. From another viewpoint, it is preferable that laser irradiation is performed in two stages when the thickness of the sapphire wafer is about 100 to 150 μm and in three stages when the thickness is 150 to 180 μm.
Thus, by forming a deteriorated layer by irradiating the inside of the sapphire wafer with a laser, even if the deteriorated layer is removed at the time of forming a groove in a subsequent process, the fine cracks caused by the laser irradiation are removed. It can be introduced in the direction, and the subsequent process can be cleaved with high accuracy at the intended position and in the intended direction.

  In general, before the laser irradiation, the sapphire wafer on which the semiconductor layer is formed is, in any order, (i) from the second conductivity type semiconductor layer side, the second conductivity type semiconductor layer, the light emitting layer, A portion of the first conductivity type semiconductor layer in the thickness direction is removed to expose the first conductivity type semiconductor layer to form a street defining one unit of light emitting element, and to the first conductivity type semiconductor layer (Ii) forming a p-side electrode and optionally a p-side pad electrode on the second conductive type semiconductor layer; (iii) exposing the first conductive type semiconductor layer It is preferable to form an n-side electrode and optionally an n-side pad electrode on the top, and (iv) grinding / polishing the back surface of the sapphire wafer to obtain the thickness of the sapphire wafer described above.

These steps are not particularly limited to methods and materials used, and can be performed using methods and materials usually performed in the field.
In particular, the street is preferably formed with a width of about 10 to 50 μm, for example. Further, the street can be formed in various directions according to the shape of the light emitting element. However, the street extends at least in one of the parallel direction and the vertical direction, preferably in both directions, with respect to the oriental flat of the sapphire wafer. It is preferable to form.
Further, the sapphire wafer is preferably ground / polished so as to have the above-described thickness when the laser irradiation and the dicing groove are formed.

  The laser irradiation described above is preferably performed inside the sapphire wafer corresponding to the position where the street is formed. The laser irradiation here is performed inside the sapphire wafer corresponding to the inside of the street (preferably the center of the street) in the street extending in parallel with the above-described oriental flat. In addition, in the street extending perpendicularly to the oriental flat, the direction in which cleavage occurs (that is, the direction in which the cleavage of the sapphire wafer is not perpendicular to the surface of the sapphire wafer due to cleavage) Laser irradiation is preferably performed inside the wafer corresponding to the shifted position. The degree of shift can be adjusted as appropriate depending on the thickness of the sapphire wafer to be cleaved, but is within the range of the wafer thickness described above, for example, about several μm to 10 μm, preferably about 3 to 8 μm, more preferably. About 4-7 micrometers is mentioned. By such a shift, the surface of the sapphire wafer, that is, the semiconductor layer side can be cleaved with high accuracy in the street, and the occurrence of cracks and chipping to the semiconductor layer can be prevented.

Subsequently, a dicing groove is formed on the second main surface (back surface) of the sapphire wafer. This dicing groove is preferably formed at a position corresponding to the deteriorated layer formed in the previous step, that is, a position where the position of the deteriorated layer existing in the thickness direction is projected onto the surface. In other words, it is preferably formed at a position on the back side of the portion where the street is formed.
The width of the dicing groove can be appropriately selected depending on, for example, the dicing blade used. For example, it is suitable to use a blade having a width of about 100 to 500 μm, preferably about 150 to 400 μm. From another viewpoint, a blade having a blade width of about twice or less, preferably about 180% or less, more preferably about 60 to 180% of the thickness of the sapphire wafer is used.
The depth of the dicing groove can be appropriately adjusted depending on, for example, the thickness of the sapphire wafer to be used. For example, the depth D is preferably within half of the thickness of the wafer, and more preferably about 1/5 to 1/2 of the wafer thickness. Specifically, about 20-80 micrometers is suitable and about 30-60 micrometers is preferable.
By forming such dicing grooves, the previously formed deteriorated layer can be removed almost completely.

When forming the dicing grooves, the sapphire wafer and the semiconductor layer can be cleaved by performing a technique such as cutter scribe and cutter grooving separately after minimizing the load due to dicing.
Alternatively, when the dicing groove is formed, the rotating blade is pressed against the sapphire wafer, so that the sapphire wafer and the semiconductor layer may be cleaved simultaneously by a load due to dicing. By simultaneously cleaving, the manufacturing process can be further simplified.

  In the present invention, by performing the above-described steps, cleaving can be performed at a predetermined position of the sapphire wafer, and damage to the semiconductor layer can be avoided. Moreover, since the recessed part resulting from a dicing groove | channel can be formed in the back surface side of a sapphire wafer as mentioned above, when a light-emitting device is assembled using this light-emitting element, the light extraction efficiency is further improved. It has an unexpected effect.

In the method for manufacturing a light emitting device according to the present invention, after obtaining the light emitting element in this way, as described above, in order to complete the light emitting device, the sapphire substrate of the cleaved light emitting element is further provided with a metal member. It is preferable to cover the entire surface of the light emitting element including the concave portion of the sapphire substrate with a sealing member containing a phosphor.
The connection of the light emitting element to the metal member and the formation of the sealing member containing the phosphor on the surface of the light emitting element can be performed by methods known in the art.

Below, the light-emitting device of this invention and the manufacturing method of a light-emitting device are demonstrated in detail.
Embodiment 1 As shown in FIG. 1A, a light-emitting device 1 according to this embodiment protects a light-emitting element 10 and connects a pair of metal members 3 functioning as terminals connected to electrodes of the light-emitting element 10 to a resin 4 The package has an opening 4a that exposes a part of the metal member 3. The light emitting element 10 is mounted in the opening 4a of the package. The light emitting device 1 is equipped with a protective element 5.

As shown in FIGS. 2A and 2B, the light emitting element 10 has a semiconductor layer 15 formed on a sapphire substrate 11. The semiconductor layer 15 is formed by laminating a first conductivity type semiconductor layer 12, a light emitting layer 13, and a second conductivity type semiconductor layer. Part of the second conductive type semiconductor layer 14, the light emitting layer 13, and the first conductive type semiconductor layer 12 in the thickness direction is removed, and an exposed portion 19 from which the first conductive type semiconductor layer 12 is exposed is formed. . Moreover, the exposed part 19 corresponding to a street is arrange | positioned in the outer periphery.
On the exposed n-type semiconductor layer 12 and the second conductive semiconductor layer 14, an n-side electrode 16 and a p-side electrode 17 are formed on substantially the entire surface of the semiconductor layers, respectively. A pad electrode 18 is formed on the p-side electrode 17.

As shown in FIG. 2B, the sapphire substrate 11 has a recess 20 formed on the side surface of the sapphire substrate 11 on the back surface 11b side. The concave portion 20 is formed by the outer edge of the back surface 11b of the sapphire substrate 11 being located inside the outer edge of the front surface 11a, and is constituted by one flat surface 21 of the sapphire substrate 11 and one surface of the package. . The depth D is about 60 μm and the width is about 100 μm. Therefore, the inclination angle is about 60 °.
Since the light emitting element 10 has a substantially rectangular shape (700 × 240 μm), the recesses are formed on two opposing faces of the square, that is, on the entire outer edge.

The light emitting element 10 described above is mounted on the metal member 3 of the light emitting device 1 so that a sapphire substrate is connected.
In addition, as shown in FIG. 1B, a recess 20 of the sapphire substrate 11 of the light emitting element 10 is further formed on the entire surface of the side surface and the upper surface of the light emitting element 10 in the opening 4 a of the package for mounting the light emitting element 10. It is covered and sealed with the sealing member 2 containing the phosphor 2b so as to be securely embedded.
As the phosphor, the yellow phosphor YAG, the sealing member is formed of a silicone resin, and the phosphor contains about 15 to 20% with respect to the weight of the entire sealing member.

(Method for manufacturing light emitting device)
The light emitting device described above can be formed by the following manufacturing method.
First, a sapphire wafer is prepared. The sapphire wafer has an oriental flat, and a sapphire wafer whose first main surface is a C plane is selected.
On the first main surface (surface) of this sapphire wafer, using a MOVPE reactor, 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 an n-type nitride semiconductor layer 14 is Si An n-type contact layer made of doped GaN is 2.165 μm, a superlattice n-type cladding layer in which a GaN layer (4 nm) and an InGaN layer (2 nm) are alternately stacked 10 times is 64 nm, and the film thickness is initially 3 nm. A well layer made of In _0.3 Ga _0.7 N and a barrier layer made of undoped GaN with a film thickness of 15 nm were alternately and repeatedly stacked from the barrier layer by six layers, and finally the barrier layer was stacked. An Mg-doped Al _0.1 Ga _0.9 N layer (4 nm) and an Mg-doped InGaN layer as a light emitting layer 16 (total film thickness 123 nm) having a multiple quantum well structure and a p-type nitride semiconductor layer 18 A p-type cladding layer of a superlattice in which (2 nm) is alternately laminated 10 times is grown in this order to a thickness of 0.2 μm and a p-type contact layer made of Mg-doped GaN in this order to produce a wafer. .
The obtained wafer is 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.
After annealing, the wafer is taken out of the reaction vessel, a mask having a predetermined shape is formed on the surface of the uppermost p-type contact layer, and etched from above the mask with an etching apparatus to expose a part of the n-type contact layer. An exposed portion 19 is formed. The exposed portion 19 is a region having an n-side electrode and a street having a width of about 20 to 30 μm arranged in the horizontal direction and the vertical direction with respect to the oriental flat.

The sapphire wafer is polished from the back surface side to a thickness of about 115 μm.
Next, the wafer is bonded to a UV sheet so that the sapphire wafer is on top, and then set in a femtosecond laser apparatus.
From the back surface side of the sapphire wafer, the altered layer is formed by a femtosecond laser at a position corresponding to the street and in a direction perpendicular to the oriental flat.
The conditions of the femtosecond laser at this time were as follows: wavelength: infrared, power: 0.15 W, processing speed: 300 mm / sec, 100 kHz.

Subsequently, an altered layer is similarly formed in a direction parallel to the oriental flat.
In this case, since the thickness of the sapphire wafer is 115 μm, the laser is irradiated in two steps from the back surface of the sapphire wafer to a depth of 37 μm and a depth of 30 μm, respectively.
Thereafter, the obtained sapphire wafer is set on a dicer, and a dicing groove is formed at a position corresponding to the street from the back surface side of the sapphire wafer. In forming the dicing groove, a blade having a sharp tip is used. First, a groove is formed in a direction parallel to the oriental flat, and the sapphire wafer and the semiconductor layer are simultaneously cut. Then, while forming a groove | channel perpendicularly | vertically with respect to an oriental flat, a sapphire wafer and a semiconductor layer are cleaved simultaneously. The groove depth here was about 60 μm.
After the break, wafer cleaning was performed.

  The sapphire wafer side of the obtained light emitting element is connected to the metal member of the package including the metal member, and the entire surface of the light emitting element is securely embedded in the recess due to the dicing grooves described above of the sapphire substrate. A sealing member containing a phosphor was coated.

The characteristics of the 15 light-emitting devices thus obtained were evaluated.
For this comparison, a light emitting device that was cleaved by cleaving without forming a dicing groove only by performing the same laser irradiation was prepared, and the same characteristic evaluation was performed.
Specifically, a current of 20 mA was applied to the obtained light emitting device, and the brightness (lm) was compared.
As a result, an average improvement in light output of about 3% was observed with respect to the comparative example. In addition, about all 15 evaluated, the tendency of an output improvement was recognized with respect to the thing of a comparative example.

In addition, for the light-emitting element in the light-emitting device of the embodiment and the light-emitting element in the light-emitting device for comparison described above, the light distribution around the light-emitting device was measured every 3 degrees to evaluate the light distribution.
As a result, as shown in FIG. 3, strong intensity was observed especially in the vicinity of the front surface and the side surface of the light emitting element of the embodiment in both directions of φ = 0 ° and 90 °.
As described above, this effectively avoids the attenuation due to the reflection of light on the back surface side of the sapphire substrate caused by the change that suddenly enters the front and back surfaces of the sapphire substrate. Then, a part of the light emitted from the light emitting element and entering the inside of the sapphire substrate is reflected by this inclination, so that the light extraction in the front direction and the light extraction from the inclined part can be increased. is there.

Further, a cut was made along the line BB ′ in FIG. 1A, the package side surface was removed, and the light emission intensity distribution of the light emitting device was measured. The measurement was performed by applying current and observing / photographing the light distribution of the light emitting element in the light emitting device with a light beam measuring system (laser beam profiler) device.
For this comparison, instead of using a silicone resin + yellow phosphor (white) as the phosphor, a light-emitting device manufactured using a silicone resin (without phosphor incorporation) was prepared, and the emission intensity distribution was similarly obtained. Was measured.
As a result, in the blue light emitting device, the strongest light emission distribution was observed in the vicinity of the light emitting layer, but in the white light emitting device, the light emission was strong even in the vicinity of the concave portion of the sapphire substrate at the same level as in the vicinity of the light emitting layer. It was confirmed that the distribution was observed.

Embodiment 2
In the light emitting device of this embodiment, as shown in FIG. 2C, the sapphire substrate 11 has a side surface on which the concave portion 30 is formed on the back surface 11 b side. The light emitting device of the first embodiment is substantially the same as that of the light emitting device of the first embodiment except that it is composed of one curved surface 31 and one surface of the package.
One curved surface 31 of the sapphire substrate 11 uses, for example, a square blade with a sharp tip when forming a dicing groove from the back surface side of the sapphire wafer in the method of manufacturing the light emitting device of the first embodiment. Is preferred.

  The semiconductor light emitting device and the manufacturing method thereof according to the present invention include various light emitting devices such as an illumination light source, various indicator light sources, an in-vehicle light source, a display light source, a liquid crystal backlight light source, a sensor light source, and a traffic light. Can be used in the way.

DESCRIPTION OF SYMBOLS 1 Light-emitting device 2 Sealing member 2b Phosphor 3 Metal member 4 Resin 4a Opening 5 Protection element 10 Light emitting element 11 Substrate 12 1st conductivity type semiconductor layer 13 Light emitting layer 14 2nd conductivity type semiconductor layer 15 Semiconductor layer 16 N side electrode 17 p-side electrode 18 pad electrode 19 exposed portion 20, 30 concave portion 21 plane 31 curved surface

Claims (6)

A light emitting device comprising a semiconductor layer stacked on the first main surface of a sapphire substrate having a first main surface and a second main surface;
A light-emitting device including a package on which the second main surface of the sapphire substrate is bonded and the light-emitting element is placed; a phosphor; and a sealing member that seals the light-emitting element;
The sapphire substrate has a concave portion in which an outer edge of the second main surface is located on an inner side of the outer edge of the first main surface, and is formed of one curved surface of the sapphire substrate and the package. A light-emitting device, wherein the phosphor is disposed inside. A light emitting device comprising a semiconductor layer stacked on the first main surface of a sapphire substrate having a first main surface and a second main surface;
A light-emitting device including a package on which the second main surface of the sapphire substrate is bonded and the light-emitting element is placed; a phosphor; and a sealing member that seals the light-emitting element;
The sapphire substrate has a concave portion in which an outer edge of the second main surface is positioned on an inner side of an outer edge of the first main surface, and is formed of one plane of the sapphire substrate and the package. A light-emitting device, wherein the phosphor is disposed inside.   The light-emitting device according to claim 1, wherein the recess is located on an outer edge of the second main surface of the sapphire substrate.   The light-emitting device according to claim 1, wherein the recess has a depth within half of the thickness of the sapphire substrate from the second main surface of the sapphire substrate.   The light emitting device according to any one of claims 1 to 4, wherein a width of the concave portion is gradually changed from the first main surface side to the second main surface side of the sapphire substrate. A semiconductor layer is laminated on the first main surface of the sapphire wafer,
Irradiating laser into the sapphire wafer from the second main surface side of the sapphire wafer to form an altered layer for cleaving,
Forming a dicing groove at a position corresponding to the second main surface and the altered layer of the sapphire wafer, and removing the altered layer;
A method for manufacturing a light emitting device, comprising: forming a light emitting element by cleaving the sapphire wafer and the semiconductor layer.

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