JP2012209294A - Light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element with improved light extraction efficiency.
A light emitting device of the present invention includes a substrate 2 and a plurality of first and second main surfaces 2A of the substrate 2 arranged so as to overlap with intersections of virtual straight lines 5 drawn in a lattice shape in plan view. The first protrusion 3a and the protrusion group 3 having a second protrusion 3b made of a material different from that of the substrate 2 disposed at a position not overlapping the first protrusion 3a, and the first protrusion of the substrate 2 so as to fill the protrusion group 3. And an optical semiconductor layer 4 provided on the main surface 2A. Since the second protrusion 3b is thus provided on the substrate 2, the light extraction efficiency of the light emitting element 1 can be improved.
[Selection] Figure 2

Description

  The present invention relates to a light emitting element using a semiconductor.

  Currently, various methods for laminating a semiconductor layer on a substrate have been proposed. In particular, when a semiconductor layer used for a light emitting element or a light receiving element is crystal-grown on a substrate, it is necessary to improve the crystal quality of the semiconductor layer.

  Thus, as a technique for crystal growth of the optical semiconductor layer on the substrate, for example, a technique for improving crystallinity of the optical semiconductor layer grown on the substrate by providing irregularities on the substrate (for example, patents) is disclosed. Reference 1).

JP 2002-164296 A

  However, in the light emitting device manufactured using the technique for growing a semiconductor layer disclosed in Patent Document 1, the light emitted in the optical semiconductor layer is only emitted from the substrate side when the irregularities are regularly provided on the substrate. It was difficult to be taken out. As a result, it has been difficult to improve the light extraction efficiency of the light emitting element.

  The present invention has been made in view of the above problems, and an object thereof is to provide a light emitting element capable of improving light extraction efficiency.

  A light emitting device according to an embodiment of the present invention includes a substrate and a plurality of first protrusions arranged on the main surface of the substrate so as to overlap with intersections of virtual lines drawn in a lattice shape in plan view. And a projection group having a second projection made of a material different from that of the substrate, disposed at a position not overlapping the first projection, and light provided on the main surface of the substrate so as to fill the projection group And a semiconductor layer.

  Since the light emitting device according to the embodiment of the present invention has the second protrusion on the substrate as described above, the light emitted from the optical semiconductor layer can be easily taken out from the second protrusion, and the light emission. The light extraction efficiency of the element can be improved.

It is a perspective view which shows the light emitting element concerning one Embodiment of this invention. It is sectional drawing which cut | disconnected the light emitting element of FIG. 1, and is equivalent to the cross section when cut | disconnected by the A-A 'line | wire. It is the top view which planarly viewed the board | substrate in the light emitting element of FIG. 1, and the dotted line has shown the virtual straight line drawn on a board | substrate. It is the top view which planarly viewed the board | substrate in the light emitting element concerning the modification of one Embodiment of this invention, (a) shows the virtual straight line drawn on a board | substrate, (b) has shown the linear area | region. The light emitting element concerning the modification of one Embodiment of this invention is shown, (a) is the top view which planarly viewed the board | substrate in this light emitting element, (b) is cut | disconnected in the light emitting element by the AA 'line | wire. FIG. The light emitting element of the prior art is shown, (a) is a plan view of the substrate of the light emitting element in plan view, and (b) is a cross-sectional view of the light emitting element taken along line B-B ′. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the semiconductor substrate concerning one Embodiment of this invention, and is equivalent to the cross section when cut | disconnected by the A-A 'line | wire of FIG. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the semiconductor substrate concerning one Embodiment of this invention. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the semiconductor substrate concerning one Embodiment of this invention. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the semiconductor substrate concerning one Embodiment of this invention. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the semiconductor substrate concerning one Embodiment of this invention. It is sectional drawing which shows 1 process of an example of embodiment of the manufacturing method of the semiconductor substrate concerning one Embodiment of this invention. It is sectional drawing which shows 1 process of the modification of embodiment of the manufacturing method of the semiconductor substrate concerning one Embodiment of this invention. It is sectional drawing which shows 1 process of the modification of embodiment of the manufacturing method of the semiconductor substrate concerning one Embodiment of this invention.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  In addition, this invention is not limited to the example of the following embodiment, A various change can be given in the range which does not deviate from the summary of this invention.

<Light emitting element>
1 is a perspective view of a light-emitting element 1 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the light-emitting element 1 shown in FIG. 1 when cut along the line AA ′ in FIG. It corresponds to a cross section. As shown in FIGS. 1 and 2, the light emitting element 1 includes a substrate 2, a protrusion group 3, and an optical semiconductor layer 4.

  The substrate 2 is made of a material capable of growing the optical semiconductor layer 4. As the substrate 2, for example, sapphire, gallium nitride, aluminum nitride, zinc oxide, or zirconium diboride can be used. The thickness of the substrate 2 is, for example, about 1 μm to 1500 μm. Here, the thickness of the substrate 2 refers to the thickness of the substrate 2 from the first main surface 2A to the second main surface 2B.

  In this example, since the light emitted from the optical semiconductor layer 4 is extracted from the substrate 2 side, the material used for the substrate 2 is considered in consideration of the transmittance of the substrate 2 at the wavelength of the light emitted from the optical semiconductor layer 4. Just choose. In this example, the substrate 2 is formed of sapphire, which is a light-transmitting material that easily transmits light emitted from the optical semiconductor layer 4. When sapphire is used as the substrate 2, for example, an A plane, a C plane, an R plane, or the like can be used as a crystal growth plane for growing a crystal.

The substrate 2 has a projection group 3 on the first main surface 2A. The protrusion group 3 includes a first protrusion 3a and a second protrusion 3b. The first main surface 2A of the substrate 2 indicates a virtual plane including the main surface on which the protrusion group 3 of the substrate 2 is not provided.

A plurality of first protrusions 3 a are provided on the first main surface 2 </ b> A of the substrate 2. The height of the first protrusion 3a from the first main surface 2A of the substrate 2 to the top is set to be 0.2 μm or more and 5 μm or less, for example. The width of the first protrusion 3a is set to 0.5 μm or more and 50 μm or less, for example. The plurality of first protrusions 3a are arranged with an interval of 0.5 μm or more and 20 μm or less, for example.

  The first protrusion 3a can be set in a polygonal column shape such as a quadrangular column shape or a hexagonal column shape, a polygonal pyramid shape such as a quadrangular pyramid shape or a hexagonal pyramid shape, or a columnar shape. When the polygonal pyramid shape is used as the first protrusion 3a, the side surface of the first protrusion 3a is inclined with respect to the first main surface 2A of the substrate 2, and the light emitted from the optical semiconductor layer 4 is reflected. It can be made difficult to be reflected by the side surface of the first protrusion 3a. In this example, the first protrusion 3a is provided with a hexagonal prism shape.

  As shown in FIG. 3A, a plurality of first protrusions 3a are arranged so as to overlap the intersections of virtual straight lines 5 drawn in a lattice shape. The virtual straight lines 5 drawn in a lattice shape are equally spaced in the x-axis direction and the y-axis direction, respectively, and the spacing is set to be, for example, 1 μm or more and 25 μm or less. Specifically, the interval h1 between the virtual straight lines 5 parallel to the x-axis direction and the interval h2 between the virtual straight lines 5 parallel to the y-axis direction are set to be equal to each other. The quadrangular region Rh surrounded by the grid constituted by the virtual straight lines 5 drawn in this way can be set to have, for example, a square shape, a rectangular shape, a trapezoidal shape, a parallelogram shape, or a rhombus shape. .

  On the other hand, the virtual straight lines 5 drawn in a lattice shape may be set such that the interval h1 between the virtual straight lines 5 parallel to the x-axis direction and the interval h2 between the virtual straight lines 5 parallel to the y-axis direction are different from each other. . Specifically, the imaginary straight line 5 parallel to the x-axis direction is set so that the interval h1 gradually decreases as it goes in one direction of the y-axis, or is set to gradually increase. May be. Thus, by setting the interval h1 and the interval h2 of the virtual straight line 5 to be different from each other, the shape of the rectangular region Rh surrounded by the lattice can be easily changed.

  The first protrusions 3a may be arranged at all the intersection positions of the virtual lines 5 drawn in a lattice shape, or may be arranged at a part of the intersection positions. In this example, since the first protrusions 3a are provided in a hexagonal column shape, the first protrusions 3a are arranged at a part of the intersection position so that the side surfaces of the hexagonal columns of the first protrusions 3a face each other. In addition, the 1st protrusion 3a should just be arrange | positioned so that it may overlap with the intersection position of the virtual straight lines 5 in planar view.

  The material of the first protrusion 3a is, for example, the same material as the substrate 2, or an oxide, fluoride, or nitride made of titanium, tantalum, aluminum, magnesium, silicon, zirconium, hafnium, yttrium, thorium, scandium, neodymium, niobium, or sodium. A material containing at least one of the above can be used. As specific materials, zirconium oxide, magnesium oxide, magnesium fluoride, hafnium oxide, silicon oxide, titanium oxide, magnesium nitride, or the like can be used.

  As shown in FIG. 3, the second protrusion 3 b is disposed on the first main surface 2 </ b> A of the substrate 2 so as not to overlap the first protrusion 3 a when the substrate 2 is viewed in plan. That is, the second protrusion 3b is disposed at a position different from the first protrusion 3a on the first main surface 2A of the substrate 2.

The second protrusion 3b may be made of a material different from that of the substrate 2, for example, an oxide or fluoride made of titanium, tantalum, aluminum, magnesium, silicon, zirconium, hafnium, yttrium, thorium, scandium, neodymium, niobium or sodium, or A material containing at least one kind of nitride can be used. As specific materials, zirconium oxide, magnesium oxide, magnesium fluoride, hafnium oxide, silicon oxide, titanium oxide, magnesium nitride, or the like can be used.

  As the second protrusion 3b, a columnar shape such as a polygonal column shape or a columnar shape, a weight shape such as a polygonal pyramid shape or a frustum shape, or a frustum shape such as a polygonal frustum shape or a truncated cone shape can be used. The second protrusion 3b may be formed to have a bottom surface that is smaller than the bottom surface of the first protrusion 3a.

As shown in FIG. 2, an optical semiconductor layer 4 is provided on the substrate 2 so as to fill the protrusion group 3. The optical semiconductor layer 4 is configured by sequentially laminating a first semiconductor layer 4a, a light emitting layer 4b, and a second semiconductor layer 4c. The total thickness of the optical semiconductor layer 4 is, for example, 0.1 μm or more 10
It can be formed as μm or less.

Examples of group III-V semiconductors include group III nitride semiconductors, gallium phosphide, or gallium arsenide. As the group III nitride semiconductor, a mixed crystal made of at least one nitride of boron, aluminum, gallium, or indium can be used. For example, gallium nitride can be used.

  The first semiconductor layer 4 a is provided on the substrate 2. The thickness of the first semiconductor layer 4a is set to 1 μm or more and 10 μm or less.

The light emitting layer 4b is provided on the first semiconductor layer 4a. As the light emitting layer 4b, a multilayer quantum well structure (MQW) in which a quantum well structure including a barrier layer having a wide forbidden band and a well layer having a narrow forbidden band is regularly stacked a plurality of times can be used. As the barrier layer and the well layer, a mixed crystal composed of a nitride of indium and gallium with the composition ratio of indium and gallium adjusted can be used. The light emitting layer 4b configured in this way has, for example, 350 n
Light with a wavelength of m or more and 600 nm or less can be emitted.

  The second semiconductor layer 4c is provided on the light emitting layer 4b. The second semiconductor layer 4c is set to exhibit a reverse conductivity type with respect to the first semiconductor layer 4a by using either electrons or holes as majority carriers. As a method for imparting conductivity type to the semiconductor layer, for example, a method of adding magnesium or silicon as an impurity can be used.

  The first electrode layer 6 is provided on the first semiconductor layer 4a, and the second electrode layer 7 is provided on the second semiconductor layer 4c. A voltage is applied to the optical semiconductor layer 4 by the first electrode layer 6 and the second electrode layer 7.

  Examples of materials for the first electrode layer 6 and the second electrode layer 7 include metals such as aluminum, titanium, nickel, chromium, indium, tin, molybdenum, silver, gold, tantalum, and platinum, or tin oxide, indium oxide, An oxide such as indium tin oxide or an alloy film such as a silver-aluminum alloy, a gold-zinc alloy, or a gold-beryllium alloy can be preferably used.

  The first electrode layer 6 and the second electrode layer 7 can be formed using a lamination method such as a sputtering method or a vapor deposition method. Further, the first electrode layer 6 and the second electrode layer 7 may be provided by laminating a plurality of layers selected from the above materials, respectively.

In this example, since the light emitted from the optical semiconductor layer 4 is extracted from the substrate 2 side, a reflective electrode material may be used as the second electrode layer 7. When a reflective electrode material is used as the second electrode layer 7, the light emitted from the optical semiconductor layer 4 can be easily reflected to the substrate 2 side, and the light extraction efficiency can be improved.

  As described above, the light-emitting element 1 of this example is configured. That is, the light-emitting element 1 of this example includes the substrate 2, the first protrusion 3 a, the second protrusion 3 b, and the optical semiconductor layer 4.

  On the other hand, as shown in FIG. 6, in the case of a light-emitting element composed of a substrate in which the first protrusions are regularly arranged in a regular grid pattern, the first protrusions are regularly arranged. When the emitted light repeats reflection with the substrate and travels in the plane direction with respect to the substrate, if the light passes through a path where the first protrusion does not exist, it is difficult to be extracted to the substrate side, and the light of the light emitting element It was difficult to improve the extraction efficiency. 6A is a plan view of the substrate in plan view, and FIG. 6B is a cross-sectional view of the light emitting element taken along the line B-B ′ in FIG. 6A in the thickness direction.

  As shown in FIG. 3, the light emitting element 1 of the present example has a first protrusion 3a and a second protrusion 3b on the first main surface 2A of the substrate 2, and the first protrusion 3a is drawn in a lattice shape. The second protrusion 3b is disposed at a position that does not overlap the first protrusion 3a while overlapping with the intersection position of the virtual lines 5.

  In the light emitting element 1 of this example, since the second protrusion 3b is arranged at a position where it does not overlap with the first protrusion 3a in this way, the light emitted from the optical semiconductor layer 4 is emitted from the substrate 2 and the optical semiconductor layer 4. When the light travels in the plane direction with respect to the substrate while repeating the reflection, the light easily enters the second protrusion 2b. The light incident on the second protrusion 3b enters the substrate 2 from the second protrusion 3b and is extracted to the substrate 2 side. As a result, the amount of light emitted from the optical semiconductor layer 4 that enters the substrate 2 increases, so that the light extraction efficiency of the light-emitting element 1 can be improved.

(Various modifications of light emitting elements)
Hereinafter, modifications of the light emitting device 1 of the present invention will be described. In addition, about the part which overlaps with the above-mentioned light emitting element 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

(Modification 1)
As shown in FIG. 4, the second protrusion 3 b is disposed at a position that does not overlap the virtual straight line 5. Here, FIG. 4 shows a plan view of the substrate 2 in plan view. In FIG. 4A, a lattice-like virtual straight line 5 drawn on the substrate 2 is shown. When the second protrusion 3b is arranged at a position where it does not overlap with the virtual straight line 5 in this way, the two linear regions 8 where the first protrusion 3a does not exist are arranged at a position where they intersect. Here, FIG. 4B shows an example of the linear region 8 on the substrate 2. Second protrusion 3b can bottom can be set to be smaller than the area of a square surrounded by the grating is set so as for example a 0.5 [mu] m ² or more 20 [mu] m ² or less.

  As a result, of the light emitted from the optical semiconductor layer 4, light that is repeatedly reflected between the substrate 2 and the optical semiconductor layer 4 in the linear region 8 is likely to enter the substrate 2 side by the second protrusion 3 b. can do. As a result, light that has been repeatedly reflected between the optical semiconductor layer 4 and the substrate 2 and is not extracted to the substrate 2 side is easily extracted to the substrate 2 side, and the light extraction efficiency of the light-emitting element 1 can be improved. .

(Modification 2)
As shown in FIG. 5, the first protrusion 3 a has an upper surface 3 </ b> A and is made of the same material as the substrate 2. Here, FIG. 5A shows a plan view when the substrate 2 is viewed in plan, and FIG. 5B shows a case where the light-emitting element 1 is cut along the line AA ′ in FIG. FIG. As shown in FIG. 5B, the first protrusion 3 a is provided integrally with the substrate 2. When the first protrusion 3a is thus provided, the optical semiconductor layer 4 can be crystal-grown from the upper surface 3A of the first protrusion 3a. The upper surface 3A of the first protrusion 3a has an area of 0.5, for example.
It is set to be not less than μm ² and not more than 10 μm ² .

  As a method for crystal growth of the optical semiconductor layer 4 on the first protrusion 3a, a lateral growth method for crystal growth in a lateral direction that is a direction perpendicular to the thickness direction of the optical semiconductor layer 4 can be used. Thus, when the optical semiconductor layer 4 is crystal-grown by lateral growth on the first protrusion 3a, dislocations extending in the thickness direction from the upper surface 3A of the first protrusion 3a can be reduced. Crystallinity can be improved.

(Modification 3)
The second protrusion 3 b is made of a material having a refractive index smaller than that of the optical semiconductor layer 4. In this example, since sapphire (refractive index 1.65) is used as the substrate 2 and gallium nitride compound (refractive index about 2.4) is used as the optical semiconductor layer 4, the refractive index of the second protrusion 3b is, for example, 1.75 to 2.30. These materials can be used.

Examples of the material of the second protrusion 3b include magnesium oxide (refractive index of about 1.68 to 1.80), zirconium dioxide (refractive index of about 1.78 to 2.00), calcium fluoride (refractive index of about 1.50 to 2.10). , Hafnium oxide (refractive index of about 1.90 or more and 2.10 or less), yttrium oxide (refractive index of about 1.80 or more and 1.90 or less) can be used. The second protrusion 3b has a refractive index between the substrate 2 and the optical semiconductor layer 4. Since it is constituted by the material having, the refractive index difference between the second protrusion 3 b and the optical semiconductor layer 4 can be made smaller than the refractive index difference between the substrate 2 and the optical semiconductor layer 4. Therefore, the critical angle at the interface between the optical semiconductor layer 4 and the second protrusion 3b can be made larger than the critical angle at the interface between the optical semiconductor layer 4 and the substrate 2, and the light emitted from the optical semiconductor layer 4 can be It can be made difficult to be reflected at the interface between the optical semiconductor layer 4 and the second protrusion 3b.

  Further, as the second protrusion 3 b, a weight having a polygonal pyramid shape or a conical shape, or a frustum shape such as a polygonal frustum shape or a truncated cone shape is used. It can be made to incline with respect to 2 A of 1st main surfaces. Thereby, the light emitted from the optical semiconductor layer 4 can be easily incident on the second protrusion 3b, and the light extraction efficiency of the light emitting element 1 can be further improved.

<Method for manufacturing light-emitting element>
7 to 14 are cross-sectional views each showing a part of the manufacturing process of the light-emitting element 1, and each corresponds to a cross section taken along the line AA 'in FIG. Portions overlapping with the above-described light emitting element 1 are denoted by the same reference numerals, and description thereof is omitted.

(Process to process the substrate)
A method of forming the first protrusion 3a on the first main surface 2A of the substrate 2 will be described with reference to FIG. As the substrate 2, a material capable of crystal growth of a semiconductor may be used. For the substrate 2, for example, sapphire, aluminum nitride, gallium nitride, silicon nitride, indium nitride, or silicon carbide can be used. In this example, a case where sapphire is used as the substrate 2 will be described.

  As the upper surface 2 </ b> A ′ of the substrate 2, for example, the substrate 2 having a uniform crystal plane can be used. If the substrate 2 is sapphire, the crystal plane of the substrate 2 can be, for example, the A-plane, C-plane or R-plane of sapphire.

As shown in FIG. 7, on the upper surface 2A ′ of the substrate 2, a mask pattern having an exposed region 9 where a part of the upper surface 2A ′ of the substrate 2 is exposed and a covering region 10 covering the other part of the upper surface 2A ′. 11 is formed. The covering region 10 of the mask pattern 11 may be set in a plan view shape, for example, the bottom shape of the first protrusion 3a formed on the first main surface 2A of the substrate 2. Therefore, the width of the covering region 10 may be set to the size of the bottom surface of the first protrusion 3a, for example, set to 0.5 μm or more and 50 μm or less.

  As the mask pattern 11, a material that can be easily removed later can be selected. For example, an oxide such as silicon oxide or a metal such as titanium can be used. The film thickness of the mask pattern 11 can be appropriately selected depending on the selection ratio between the etching rate of the substrate 2 and the etching rate of the mask pattern 11 if a part of the substrate 2 is removed by etching, for example, 200 nm or more. It can be set to 3500 nm or less.

  The mask pattern 11 can be formed by laminating a laminated film on the substrate 2 by using a vacuum laminating method such as a sputtering method or a vapor deposition method, and patterning the exposed region 9 and the covering region 10. At this time, if dry etching is performed using sapphire as the substrate 2, a chlorine-based gas that easily reacts with sapphire can be used as a reactive gas. In this case, as a mask material, titanium, nickel Alternatively, a metal such as chromium or a chlorine-resistant inorganic material such as silicon oxide may be used.

  Next, as shown in FIG. 8, a part of the substrate 2 is removed in the thickness direction by an etching method or the like from the exposed region 9 where a part of the upper surface 2A 'of the substrate 2 is exposed. As a method for removing a part of the substrate 2, an etching method such as wet etching or dry etching can be used. Here, when a flat crystal face with aligned crystals is used as the upper face 2A ′ of the substrate 2, the upper face 3A of the first first protrusion 3a is covered with the covering region 10 of the mask pattern 11. Therefore, the flatness of the upper surface 2A ′ (the upper surface 3A of the first protrusion 3a) of the substrate 2 covered with the covering region 10 of the mask pattern 11 can be maintained during the process of removing a part of the substrate 2. it can.

  When sapphire is used as the substrate 2, when part of the substrate 2 is removed by dry etching, productivity can be improved by performing dry etching in a chlorine-based gas atmosphere that easily reacts with sapphire. it can. Thereafter, by removing the mask pattern 11 from the substrate 2, a plurality of first protrusions 3a can be provided integrally with the substrate 2 on the first main surface 2A of the substrate 2, as shown in FIG.

  In this example, the case where the substrate 2 having the flat upper surface 2A ′ is described, but the substrate 2 having a low flatness of the upper surface 2A ′ may be used. In this case, a step of polishing the upper surface 3A of the first protrusion 3a after the first protrusion 3a is provided on the substrate 2 and the mask pattern 11 is removed may be provided. By polishing the upper surface 3A of the first protrusion 3a after removing the mask pattern 11 in this way, a part of the mask pattern 11 or a deposit such as a release agent remaining on the upper surface 3A of the first protrusion 3a is removed. In addition, the upper surface 3A can be flattened.

  Further, instead of the step of removing the mask pattern 11, a step of polishing from above the mask pattern 11 to the upper surface 3A of the first protrusion 3a may be employed. In this case, the process of removing the mask pattern 11 and the process of flattening the upper surface 3A of the first protrusion 3a can be performed continuously, and productivity can be improved.

(Step of forming the second protrusion)
Next, the second protrusion 3 b is formed on the first main surface 2 </ b> A of the substrate 2. The second protrusion 3b may be made of a material different from that of the substrate 2, for example, an oxide or fluoride made of titanium, tantalum, aluminum, magnesium, silicon, zirconium, hafnium, yttrium, thorium, scandium, neodymium, niobium or sodium, or An inorganic material containing at least one kind of nitride can be used. Specific materials include zirconium oxide,
Magnesium oxide, magnesium fluoride, hafnium oxide, silicon oxide, titanium oxide, magnesium nitride, or the like can be used.

  Thus, by forming the second protrusion 3b from an amorphous material among the inorganic materials, the optical semiconductor layer 4 grows from the second protrusion 3b while the optical semiconductor layer 4 grows from the first protrusion 3a. Can be suppressed.

  In order to form the second protrusion 3b, first, a deposition layer 12 on which a material to be the second protrusion 3b is deposited is formed on the substrate 2. The deposited layer 12 is formed by depositing, for example, using a sputtering method, a vapor deposition method, a spin coating method, or the like, and then patterning. The thickness of the deposited layer 12 may be set to a height at which the second protrusion 3b is formed, and is set to be 0.02 μm or more and 5 μm or less, for example.

  Specifically, as shown in FIG. 10, a material to be the deposition layer 12 is deposited on the first main surface 2A of the substrate 2 by a sputtering method. Thereafter, as shown in FIG. 11, the second protrusion 3b is formed on the deposited film 12 by using a general etching method or a photolithography method.

  In this example, as shown in FIG. 2, the second protrusion 3b is provided so as to be positioned between the first protrusions 3a. That is, the second protrusion 3b is provided so as not to overlap with the first protrusion 3a disposed at the intersection of the virtual lines 5 drawn in a lattice shape in plan view. The second protrusion 3b is arranged so that the area occupation ratio is, for example, 10% or more and 90% or less with respect to the first main surface 2A where the first protrusion 3a is not provided when the substrate 2 is viewed in plan. ing.

(Process for growing an optical semiconductor layer)
Next, as shown in FIG. 12, the optical semiconductor layer 4 is grown on the substrate 2. As shown in FIG. 12, the optical semiconductor layer 4 is crystal-grown on the substrate 2 so as to fill the first protrusions 3a therein.

As the optical semiconductor layer 4, for example, a group III-V semiconductor can be used. In this example, the optical semiconductor layer 4 is made of gallium nitride. As a method for growing the optical semiconductor layer 4 on the upper surface 2A of the substrate 2, a molecular beam epitaxial method, a metal organic epitaxial method, a hydride vapor phase growth method, a pulse laser deposition method, or the like can be used.

  As a method for growing the optical semiconductor layer 4, for example, the optical semiconductor layer 4 can be grown in a plane direction parallel to the first main surface 2 </ b> A more easily than a vertical direction perpendicular to the first main surface 2. Directional growth can be used. Specifically, the optical semiconductor layer 4 can be grown in the lateral direction by adjusting the growth conditions such as the composition ratio, the growth temperature, and the growth pressure in each layer of the optical semiconductor layer 4.

In order to epitaxially grow gallium nitride as the optical semiconductor layer 4 on the substrate 2, growth conditions such as the composition ratio, growth temperature, and growth pressure of gallium nitride may be adjusted. The growth temperature can be set to 350 ° C. or higher and 1500 ° C. or lower, for example. When the low temperature buffer layer of the first semiconductor layer 3a made of gallium nitride is provided on the substrate 2, the growth temperature can be set to 350 ° C. or higher and 800 ° C. or lower, for example.

  In this way, the light-emitting element 1 can be manufactured by growing the optical semiconductor layer 4 on the substrate 2.

(Modification of manufacturing method of light emitting element)
Before the step of crystal growth of the optical semiconductor layer 4, as shown in FIGS.
A step of growing a crystal body 13 having a crystal side surface 13a inclined with respect to the upper surface 4A on the upper surface 3A of a may be included.

In the case where gallium nitride is used for the crystal body 13 as the optical semiconductor layer 4, a method for forming a crystal body having a crystal side surface 13a inclined with respect to the upper surface 3A of the first protrusion 3a is, for example, 20 kPa or more and 90 kPa. Crystal growth may be performed at the following pressure and at a temperature of 700 ° C. to 1150 ° C. By growing the crystal under such conditions, the crystal 13 can be grown on the upper surface 3A of the first protrusion 3a of the substrate 2 as shown in FIG. The crystal side surface 13a of the crystal 13 can be, for example, a {1-101} plane when the upper surface 3A of the first protrusion 3a of the substrate 2 made of sapphire is a c plane.

  After that, as shown in FIG. 14, the crystal body 13 is grown in the lateral direction and bonded to the adjacent crystal body 13. Dislocations extending in the thickness direction of the optical semiconductor layer 4 are formed by growing crystal bodies 13 in the lateral direction and bonding them to adjacent crystal bodies 13 to bond dislocations extending from the upper surface 3A of each first protrusion 3a. Can be reduced.

  Thus, by reducing the number of dislocations extending in the thickness direction of the optical semiconductor layer 4, the crystal quality of the optical semiconductor layer 4 can be improved, and the light emission efficiency of the optical semiconductor layer 4 can be improved. Further, when dislocations are combined in the first semiconductor layer 4a of the optical semiconductor layer 4, dislocations extending to the light emitting layer 4b can be reduced, so that a region emitting light in the light emitting layer 4b can be widened. it can.

  Furthermore, the optical semiconductor layer 4 can be grown in the lateral direction by growing the crystal in a high temperature state set to be higher than the temperature at the time of forming the crystal side surface 13a and a low pressure state set to be equal to or lower than the pressure at the time of forming the crystal side surface 13a. .

  Thus, by growing the crystal body 13 and growing the optical semiconductor layer 4, the light emission efficiency of the light emitting element 1 can be improved, and the amount of light extracted from the light emitting element 1 can be increased.

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Substrate 2A 1st main surface 2B 2nd main surface 2 'Upper surface 3 Protrusion group 3a 1st protrusion 3A Upper surface 3b 2nd protrusion 4 Optical semiconductor layer 4a 1st semiconductor layer 4b Light emitting layer 4c 2nd semiconductor layer 5 Virtual Straight line 6 First electrode 7 Second electrode 8 Linear region 9 Exposed region
10 Covered area
11 Mask pattern
12 Deposited layer
13 Crystal
13a Crystal side

Claims (4)

A substrate,
A plurality of first protrusions arranged on the main surface of the substrate in a plan view so as to overlap with intersections of virtual straight lines drawn in a lattice shape, and arranged at positions not overlapping with the first protrusions, A protrusion group having a second protrusion made of a material different from that of the substrate;
A light-emitting element having an optical semiconductor layer provided on the main surface of the substrate so as to fill the protrusion group.   The light emitting device according to claim 1, wherein the second protrusion is disposed at a position not overlapping the virtual line.   The light emitting device according to claim 1, wherein the first protrusion has an upper surface and is made of the same material as the substrate.   The light emitting element according to claim 1, wherein the second protrusion has a refractive index smaller than a refractive index of the optical semiconductor layer.

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