JPWO2010074287A1 - Light emitting diode element and light emitting diode module - Google Patents

Abstract

An object of the present invention is to reflect light emitted from a semiconductor light emitting layer of a light emitting diode in a lateral direction in a condensing direction, thereby providing a light emitting diode element having high luminance and light condensing efficiency, and the same on a single substrate. An array of light emitting diode modules is provided. Therefore, it is possible to form a side reflection portion on the substrate of the light emitting diode, which reflects light emitted from the light emitting layer at a position close to the side surface of the light emitting layer. The light emitted from the active layer in the condensing direction is emitted as it is, and the light emitted in the direction opposite to the condensing direction is reflected by the back reflecting film and emitted in the condensing direction, and in the direction along the active layer. The emitted light is reflected by the side reflecting portion and emitted in a substantially condensing direction.

Description

  The present invention relates to a light emitting diode element and a light emitting diode module, and more specifically, by incorporating a structure in which light emitted from a light emitting layer in a side surface direction is reflected in a light collecting direction perpendicular to the light emitting layer, luminance and light collecting. The present invention relates to a light emitting diode and a light emitting diode module that improve efficiency.

  A conventional light emitting diode (LED) element has, for example, a structure shown in FIG. 56 (see Patent Document 2). A light emitting element 791 made of GaAlN or the like is mounted on a metal stem, and electrodes are taken out through wire bonding to metal posts 792 and 793. The phosphor 795 is excited by the ultraviolet light emitted from the light emitting element 791, and light having a long wavelength is emitted.

  In another example of the conventional LED element, as shown in FIG. 57, a light emitting element 891, a package substrate 892 on which the light emitting element is mounted, a lead 893 for taking out an electrode from the package to the outside, a bond wire 894, a phosphor 895, It is composed of a cover glass 896 or the like. Light is emitted to the outside through the cover glass 896. FIG. 58A is a plan view of the light emitting element 891 as viewed from above, and FIG. 58B is an X-X ′ sectional view thereof. The light emitting element 891 is a semiconductor made of GaAlN or the like formed on a sapphire substrate 991, and this semiconductor is composed of an N-type semiconductor layer 992 and a P-type semiconductor layer 994 with an active layer 993 interposed therebetween. Reference numeral 9921 denotes an outer edge of the semiconductor, and 9923 denotes a boundary between the N-type semiconductor layer and the P-type semiconductor layer. Bonding pad portions (electrodes) 996 and 997 are provided on the N-type semiconductor layer 992 and the P-type semiconductor layer 994, respectively. A reflective film 995 is provided on the lower surface of the sapphire substrate 991.

  Originally, from the active layer of the light emitting element that emits light, not only the direction in which the cover glass or the like is disposed (condensing direction), but also the opposite direction or a direction perpendicular to the condensing direction, that is, the side surface of the light emitting element Also released in the direction. Conventionally, light emitted from the active layer in the condensing direction is extracted as it is in the condensing direction, and light emitted from the active layer in the direction opposite to the condensing direction is reflected by the reflective film and extracted in the condensing direction. ing. Light emitted in a direction perpendicular to the light collecting direction is mostly attenuated by scattering, but the remaining light is reflected by tilting the inner wall surface of the light emitting diode package, etc. (See Patent Documents 1 and 3). However, the use of the light emitted in the direction perpendicular to the light collecting direction is limited.

JP 2006-303547 A JP-A-10-93146 W02006-126330

  In general, light emitted from an active layer of a semiconductor layer (light emitting layer) constituting a light emitting diode is perpendicular to the surface side of the light emitting layer (condensing direction) and the back side of the light emitting layer, that is, the light collecting direction. A substantially equivalent amount of light is emitted in the opposite direction to the direction and the direction substantially along the light emitting layer, that is, the direction (side surface direction) perpendicular to the light collecting direction. Although the light emitting layer is a thin film, in many cases, the amount of light emitted in the lateral direction is as large as about 40% of the whole. For this reason, in order to improve the luminance of the light emitting diode comprehensively, a structure for efficiently extracting light emitted from the light emitting layer in the side surface direction in the light collecting direction is required.

Of the light emitted from the light-emitting layer, if the light emitted in the direction substantially along the light-emitting layer is reflected and directed in the light collecting direction, the light emitted from the light-emitting layer can be used without waste. It is considered that the luminance of the light emitting diode can be increased. For example, as shown in FIG. 1, by tilting the wall surface inside the light emitting diode package 97, the light emitted from the light emitting element 100 in the side surface direction can be reflected in the light collecting direction z. Further, in order not to place a light shielding object such as an electrode in the optical path, it is conceivable to employ a structure in which the electrode is taken out from the side opposite to the light condensing direction by using a flip chip technique.
The light emitting element 100 is a chip cut to about 1 mm square, and includes a semiconductor layer (light emitting layer) using, for example, GaAlN on the lower surface of the sapphire substrate 30. The light emitting layer includes a P-type semiconductor layer 40a and an N-type semiconductor layer 40b, and a reflective film 50 is provided on the lower surface of the light emitting layer. Light is emitted from the active layer formed at the interface between the P-type semiconductor layer 40a and the N-type semiconductor layer 40b. Among them, the light emitted to the sapphire substrate 30 side is extracted upward (condensing direction z) through the sapphire substrate. The light emitted from the active layer in the direction opposite to the sapphire substrate 30 is reflected by the reflective film 50 and extracted in the light collecting direction z. Further, by inclining the inner side surface of the package 97 in a tapered shape, light emitted from the active layer in the side surface direction (direction perpendicular to the light collecting direction z) can be reflected in the light collecting direction. . A phosphor 90 that emits light having a longer wavelength when excited by light from the light emitting element and a transparent cover cap (cover glass) 98 are disposed on the light collection element z side of the light emitting element 100. Yes. Thereby, the light of the light emitting element excites the fluorescent material of the phosphor to emit light, and the light is emitted to the outside through the cover glass.
In addition, the electrodes of the light emitting element 100 are preferably arranged so as not to interfere with the optical path. Therefore, the flip chip electrode 81a electrically connected to the P-type semiconductor layer of the light-emitting layer through the wiring inside the light-emitting element, and the flip chip electrode 81b electrically connected to the N-type semiconductor layer are defined as a light collecting direction z. Is provided on the opposite side. Each flip chip electrode is electrically connected to a conductor on the substrate of the package substrate 94. The electrodes of the light emitting element 100 are further electrically connected to the outside through conductor wiring and leads 85 in the package substrate.

  However, in order to reflect the light emitted from the light emitting layer in the lateral direction in the condensing direction, much light is attenuated inside the light emitting element before reaching the end face of the light emitting element and further to the outside of the element. Since the light is scattered at the element interface, light cannot be efficiently captured unless a mirror is formed at a position close to the light emitting layer. That is, in order to suppress the attenuation of light in the direction substantially along the light emitting layer, it is necessary to make the optical path in the light emitting element in that direction as short as possible. For this reason, it is necessary to make the size of the light emitting layer as small as possible and to install a mirror that reflects light in the vicinity of the light emitting layer. However, such a configuration has been put to practical use because it is difficult to form a mirror inclined with respect to the light emitting layer because the light emitting element is as small as 1 mm square and the thickness of the light emitting layer is as thin as several microns. There is no reality. For this reason, the light that can be effectively used out of the light emitted from the light emitting layer is only the light emitted in the condensing direction and the light emitted in the opposite direction and reflected by the reflective film on the back surface. It is no exaggeration to say. Light emitted in a direction perpendicular to the light collecting direction, that is, light emitted in a direction substantially along the light emitting layer is almost absorbed or scattered, and is not used effectively.

  In order to form a mirror at a position close to the light emitting portion, it is preferable to separate the light emitting elements into several parts. However, two demerits occur when the elements are divided into elements having a small area to form a set. One is that a space for separating the elements is required, and this space usually has no function other than the separation, and there is a disadvantage in terms of area efficiency. Another disadvantage is that the ratio of the part closer to the end face than the center part of the element is higher, and the light emission efficiency due to the discontinuity of the crystal is lower in the vicinity of the end face. The light emission efficiency is disadvantageous in the assembly of elements. This is based on a mathematical principle that the ratio of the end faces is proportional to the length of one side of the element, and the area of the element is proportional to the square of the length of one side. Because of these disadvantages, it is not usually possible to divide the elements into elements with a small area and make the set as a set. However, if the light emitted from the light emitting layer in the lateral direction is reflected in the light collecting direction perpendicular to the light emitting layer, and the light in the lateral direction can be actively used, the element size is reduced. The positive effect of suppressing the attenuation in the lateral direction, the negative effect of increasing the end face ratio by reducing each of the light emitting parts, and the negative effect of requiring a separation space between the light emitting parts Can be offset to create a significant positive effect that exceeds the disadvantages.

  The present invention has been made in view of such circumstances, and incorporates a structure for directing light emitted in all directions from the light emitting layer of the light emitting element in the light collecting direction at a position close to the side surface of the light emitting layer. Accordingly, an object of the present invention is to provide a light emitting diode and a light emitting diode module with high luminance and light collection efficiency.

The present invention is as follows.
1. A light-emitting diode element comprising a light-emitting layer formed in a certain area on a substrate by a thin film, and taking out light emitted from the light-emitting layer in a condensing direction perpendicular to the light-emitting layer, near a side surface of the light-emitting layer A side reflecting portion inclined at an angle within a predetermined range with respect to the light emitting layer, and light emitted from the light emitting layer in a direction substantially parallel to the light emitting layer is substantially collected by the side reflecting portion. A light-emitting diode element that is reflected on the surface.
2. The side reflecting portion is formed so as to surround all or part of the side surface of the light emitting layer, and the angle in the predetermined range is 0 degree or more and 90 degrees or less. The light emitting diode element of description.
3. A back reflection film is further provided on the side opposite to the light collection direction across the light emitting layer, and light emitted from the light emitting layer to the side opposite to the light collection direction is reflected in the light collection direction by the back reflection film. Reflecting 1. Or 2. The light emitting diode element as described in.
4). The said light emitting layer and the said side reflection part are formed on the surface of the said condensing direction side of the said board | substrate. To 3. The light-emitting diode element according to any one of the above.
5. The substrate is a transparent substrate that transmits light emitted from the light emitting layer, and the back reflective film is formed on a surface of the transparent substrate opposite to the light collecting direction. The light emitting diode element of description.
6). A wall surface formed on the substrate surrounding the side surface of the light emitting layer and facing the side surface of the light emitting layer is inclined at an angle of the predetermined range, and at least on the wall surface facing the side surface of the light emitting layer. 4. The formed reflective film constitutes the side reflecting portion. Or 5. The light emitting diode element as described in.
7). The substrate is a transparent substrate that transmits light emitted from the light emitting layer, and the light emitting layer is formed on a surface of the transparent substrate opposite to the light collecting direction. To 3. The light-emitting diode element according to any one of the above.
8). A transmissive membrane layer formed so as to transmit light emitted from the light emitting layer so as to cover at least a side surface of the light emitting layer and to have a thickness that is thick on the substrate side and thin toward the opposite side; The reflection film formed on the outer surface of the transmission film layer constitutes the side reflection part. The light emitting diode element of description.
9. The light emitting layer is formed in a substantially trapezoidal shape that is wide on the substrate side and narrows toward the opposite side, and transmits light emitted from the light emitting layer so as to cover at least the side surface of the light emitting layer. The reflective film formed on the outer surface of the transmission film layer constitutes the side reflection part. The light emitting diode element of description.
10. The substrate includes a transparent substrate that transmits light emitted from the light emitting layer and a second substrate, and the light emitting layer formed on a surface of the transparent substrate opposite to the light collecting direction. And the side reflection part formed on the second substrate so as to correspond to the light emitting layer, and the transparent substrate on which the light emitting layer is formed and the side reflection part are formed. 1. The above-mentioned 1. constructed by bonding the second substrate to face each other. To 3. The light-emitting diode element according to any one of the above.
11. In order from the transparent substrate side, a first conductive layer that transmits light emitted from the light-emitting layer and has conductivity, the light-emitting layer, a second conductive layer that has conductivity, a power wiring layer, And at least two flip chip electrodes or flip chip electrodes disposed on the power wiring layer, wherein the first wiring layer is electrically connected to the first conductive layer in the power wiring layer. A conductor and a second conductor electrically connected to the second conductive layer are respectively wired, and each of the flip chip electrode or the flip chip electrode includes the first conductor and the second conductor. 6. Each of which is electrically connected. To 10. The light-emitting diode element according to any one of the above.
12 10. The above-described 11. configuration wherein the flip-chip electrode or flip-chip electrode is disposed on the power wiring layer and then the transparent substrate is removed. The light emitting diode element of description.
13. Further, the exposed surface of the first conductive layer that has been in contact with the removed transparent substrate is processed into a finish. The light emitting diode element of description.
14 A phosphor including a fluorescent material is further disposed on the light collecting direction side of the light emitting layer, and the fluorescent material absorbs at least part of the light emitted from the light emitting layer and emits light having a different wavelength. 1 above. Thru 13. The light-emitting diode element according to any one of the above.
15. 1 above. To 10. A light emitting diode module comprising: a plurality of the light emitting diode elements according to any one of the above items formed on one substrate, and the light emitting diode elements being electrically connected to each other.
16. Said 7. To 10. A plurality of the light-emitting diode elements according to any one of the above are formed on one substrate, and each of the light-emitting diode elements transmits light emitted from the light-emitting layer in order from the transparent substrate side and has conductivity. A first conductive layer, the light emitting layer, and a second conductive layer having conductivity; and a power wiring layer and a power wiring layer disposed on the plurality of light emitting diode elements. A first conductor electrically connected to the first conductive layer in the power supply wiring layer, and the second conductive layer. Each of the electrically connected second conductors is wired, and each of the flip chip electrodes or flip chip electrodes is configured to be electrically connected to the first conductor and the second conductor, respectively. That LED module according to symptoms.
17. 16. The structure according to 16, wherein the transparent substrate is removed after the flip chip electrode or the flip chip electrode is disposed on the power wiring layer. The light emitting diode module of description.
18. Further, the exposed surface of the first conductive layer that has been in contact with the removed transparent substrate is processed into a ground surface. The light emitting diode module of description.
19. A phosphor including a fluorescent material is further disposed on the light collecting direction side from the plurality of light emitting layers, and the fluorescent material absorbs at least a part of light emitted from each of the light emitting layers and has a different wavelength. 15. emitting light. To 18. The light emitting diode module according to any one of the above.

According to the light emitting diode element of the present invention, the side reflection part inclined at an angle within a predetermined range with respect to the light emitting layer is provided in the vicinity of the side surface of the light emitting layer formed on the substrate by the thin film, and The light emitted in the direction substantially parallel to the light is reflected in the direction substantially perpendicular to the light emitting layer by the side reflecting portion, so that not only the light emitted from the light emitting layer in the light collecting direction perpendicular to the light emitting layer but also the light emitting layer Light emitted in the parallel direction can be extracted in the light collecting direction. A fine side reflection portion can be formed on one substrate using semiconductor technology, and the configuration of the present invention can be applied not only to a white light emitting diode but also to an existing single color light emitting diode. . As a result, the brightness of the light emitting diode element can be increased overall, and it is possible to realize an energy efficient light emitting diode element by maximizing the amount of light collected per injection current into the light emitting diode element.
The side reflecting portion is formed so as to surround all or part of the side surface of the light emitting layer, and is substantially parallel to the light emitting layer when the angle in the predetermined range is not less than 0 degrees and not more than 90 degrees. Most or most of the light emitted in any direction can be extracted and used in a substantially condensing direction.
In the case where a back reflection film is further provided on the side opposite to the light collection direction across the light emitting layer, the light emitted from the light emitting layer to the side opposite to the light collection direction is condensed by the back reflection film. Therefore, light emitted from the light emitting layer in all directions can be extracted in the light collecting direction, and a light emitting diode element with further excellent luminance and energy efficiency can be realized.

When the light emitting layer and the side reflecting portion are formed on the surface of the substrate on the light collecting direction side, the light emitting layer and the side reflecting portion are easily manufactured using existing semiconductor technology. be able to. In addition, the electrodes and wirings for driving the light emitting diode elements can be integrated with a simple structure.
When the substrate is a transparent substrate that transmits light emitted from the light emitting layer, and the back reflection film is formed on the surface of the transparent substrate opposite to the light collecting direction, A back reflecting film can be easily formed on the entire surface.
A wall surface formed on the substrate so as to surround the side surface of the light emitting layer and opposed to the side surface of the light emitting layer includes a side wall portion inclined at an angle of the predetermined range, and is formed on at least the wall surface facing the side surface of the light emitting layer. When the reflecting film constitutes the side reflecting portion, the light emitting layer and the side reflecting portion can be formed by a series of processes using the same material, and the light emitting diode having the side reflecting portion built-in It becomes possible to manufacture the element efficiently.

When the substrate is a transparent substrate that transmits light emitted from the light emitting layer, and the light emitting layer is formed on a surface of the transparent substrate opposite to the light collecting direction, an existing semiconductor is used. A light emitting layer, a back reflection film, an electrode and the like can be easily formed using a technique. In addition, it is possible to easily arrange the phosphor so as to cover the condensing direction side of the transparent substrate. When the phosphor is provided, the light reaching the light emitting layer directly or reflected by the phosphor is reflected by the phosphor. Can be captured.
Comprising a transmissive layer that transmits light emitted from the light-emitting layer, covers at least the side surface of the light-emitting layer, and is formed so as to be thicker on the substrate side and thinner toward the opposite side; When the reflective film formed on the outer surface of the transmissive layer constitutes the side reflecting portion, the light emitting layer and the side reflecting portion are formed on the same substrate surface using the same material through a series of steps. Therefore, it is possible to efficiently manufacture a light emitting diode element incorporating a side reflecting portion.
The light emitting layer is formed in a substantially trapezoidal shape that is wide on the substrate side and narrows toward the opposite side, and transmits light emitted from the light emitting layer so as to cover at least the side surface of the light emitting layer. When the reflective film formed on the outer surface of the transmissive film layer constitutes the side reflecting portion, the light emitting layer and the side reflecting portion are made of the same material on the same substrate surface. It can be formed by a series of processes, and it becomes possible to efficiently manufacture a light emitting diode element incorporating a side reflecting portion.

  The substrate includes a transparent substrate that transmits light emitted from the light emitting layer and a second substrate, and the light emitting layer formed on a surface of the transparent substrate opposite to the light collecting direction. The side reflection part formed on the second substrate so as to correspond to the light emitting layer, and a second substrate in which the transparent substrate on which the light emitting layer is formed and the side reflection part is formed. In the case where the substrate is configured so as to be opposed to each other, the side reflection portion having a preferable inclination angle can be formed by etching the silicon substrate or the like, so that a light emitting diode element having excellent light collecting performance is realized. be able to.

In order from the transparent substrate side, a first conductive layer that transmits light emitted from the light emitting layer and has conductivity, a light emitting layer, a second conductive layer having conductivity, and a power supply wiring layer are provided. A first conductor electrically connected to the first conductive layer in the power wiring layer, and further comprising at least two flip chip electrodes or flip chip electrodes disposed on the power wiring layer. And a second conductor electrically connected to the two conductive layers, and the flip chip electrodes and the like are electrically connected to the first conductor and the second conductor, respectively. The light emitting layer and the electrode for driving the light emitting layer, the power supply wiring, the flip chip electrode, and the like can be integrally formed, and the light emitting layer is directly or reflected from the light emitting layer and collected by the electrode and the power supply wiring. Light emitted in the light direction Since not blocking, it is possible to a light-emitting diode device having excellent light-converging power.
In the case where the transparent substrate is removed after the flip chip electrode or the like is disposed on the power wiring layer, it is possible to reduce the attenuation of light in the transparent substrate. Will increase.
Furthermore, when the exposed surface of the first conductive layer that has been in contact with the removed transparent substrate is processed into a ground, the total reflectance of light on the surface can be reduced, The light collecting performance can be further enhanced.

  When a phosphor including a fluorescent material is further disposed on the light collecting direction side of the light emitting layer, and the fluorescent material absorbs at least a part of the light emitted from the light emitting layer and emits light of a different wavelength. Makes it possible to obtain light of a desired color (for example, white light) by converting the color of the light emitted from the light emitting layer or combining it with the light emitted from the light emitting layer. The phosphor can capture or pass light emitted from the light emitting layer directly or reflected and emitted in the light collecting direction.

  According to the light-emitting diode module of the present invention, a plurality of light-emitting diode elements each having the above-described side reflection portion are formed on one substrate, and each light-emitting diode element is electrically connected. Using the technology, the light emitting diode elements can be arranged and manufactured on a single wafer, and a light emitting diode module having excellent packaging space efficiency can be obtained. As a result, it is possible to realize a light-emitting diode module that is small in size, high in luminance, and high in energy efficiency.

Each of the light emitting diode elements includes a transparent first conductive layer, a light emitting layer, and a second conductive layer in order from the transparent substrate side, and further, a power supply wiring is provided on the plurality of light emitting diode elements. And at least two flip chip electrodes or flip chip electrodes provided on the power wiring layer, wherein the first conductor connected to the first conductive layer in the power wiring layer and the second conductive When the second conductor connected to the layer is wired and each flip chip electrode is electrically connected to the first conductor and the second conductor, each light emitting diode element The light emitting layer and the electrode for driving the light emitting layer, the power supply wiring between the light emitting diode elements, the flip chip electrode, and the like can be integrally formed. Or Because directly or is reflected does not block the light emitted to the condensing direction, it is possible to a light emitting diode module with excellent condensing performance.
In the case where the transparent substrate is removed after the flip chip electrode or the like is disposed on the power supply wiring layer, light attenuation in the transparent substrate can be reduced. Will increase.
Furthermore, when the exposed surface of the first conductive layer that has been in contact with the removed transparent substrate is processed into a ground, the total reflectance of light on the surface can be reduced, The light collecting performance can be further enhanced.

  A light emitter containing a fluorescent material is further disposed on the light collecting direction side from the plurality of light emitting layers, and the fluorescent material absorbs at least part of the light emitted from each light emitting layer and emits light of different wavelengths. In the case of emitting light, the light emitting layers of a plurality of light emitting diode elements may be provided together to provide one phosphor, and the color of light emitted from each light emitting layer is converted, or the light emitted from each light emitting layer and By combining them, it becomes possible to obtain light of a desired color (for example, white light). The phosphor can capture or pass light emitted directly or reflected from each light emitting layer in the light collecting direction.

The present invention will now be described in the following detailed description, with reference to the referenced drawings, by way of example of exemplary embodiments according to the present invention. Like reference numerals designate like parts or configurations throughout the several views of the drawings.
It is sectional drawing for demonstrating the structure of a light emitting diode element. It is sectional drawing which shows the basic composition of the light emitting diode element (optical microcell) of this invention. It is a top view of the light emitting diode element of FIG. It is sectional drawing which shows another basic structure of the light emitting diode element of this invention. 3 is a diagram for explaining a relationship between an inclination angle of a side reflection portion (micromirror) built in the light emitting diode element of the present invention and a direction of reflected light. FIG. 3 is a plan view showing a configuration example of a light emitting diode module (optical micromodule) in the first embodiment. It is a top view for demonstrating one light emitting diode element which comprises the light emitting diode module of FIG. It is a top view for demonstrating the electrical connection method between the light emitting diode elements which comprise the light emitting diode module of FIG. It is a top view for demonstrating the electrical connection method of the light emitting diode element which comprises the light emitting diode module of FIG. 6, and an electrode part. FIG. 7 is an equivalent circuit diagram of the light emitting diode module of FIG. 6. FIG. 8 is a cross-sectional view for explaining a first structural example of the light-emitting diode element in the first embodiment (corresponding to the YY ′ cross-section in FIG. 7). FIG. 8 is a cross-sectional view for explaining a first structural example of the light-emitting diode element in the first embodiment (corresponding to the Y ₂ -Y ₂ ′ cross-section in FIG. 7). FIG. 7 is a cross-sectional view for explaining a first structure example of the light-emitting diode module in Embodiment 1 and a traveling direction of light (corresponding to the XX ′ cross-section of FIG. 6). FIG. 6 is a cross-sectional view for explaining the first manufacturing method of the light-emitting diode element or light-emitting diode module according to Embodiment 1. It is sectional drawing for demonstrating the process of forming a side reflection part among the manufacturing methods of the light emitting diode element shown in FIG. FIG. 6 is a cross-sectional view for explaining the traveling direction of light according to the first structure of the light-emitting diode element of the first embodiment. FIG. 8 is a cross-sectional view for explaining a second structure example of the light-emitting diode element in the first embodiment (corresponding to the YY ′ cross-section in FIG. 7). FIG. 8 is a cross-sectional view for explaining a second structure example of the light-emitting diode element in the first embodiment (corresponding to the Y ₂ -Y ₂ ′ cross-section in FIG. 7). FIG. 7 is a cross-sectional view for explaining a second structure example of the light-emitting diode module according to Embodiment 1 and a traveling direction of light (corresponding to the XX ′ cross-section of FIG. 6). 6 is a cross-sectional view for explaining a second manufacturing method of the light-emitting diode element or light-emitting diode module according to Embodiment 1. FIG. FIG. 10 is a cross-sectional view for explaining a third structural example of the light-emitting diode element in the first embodiment (corresponding to a YY ′ cross-section in FIG. 7). FIG. 10 is a cross-sectional view for explaining a third structural example of the light-emitting diode element in the first embodiment (corresponding to the Y ₂ -Y ₂ ′ cross-section in FIG. 7). 6 is a cross-sectional view for explaining a third manufacturing method of the light-emitting diode element or the light-emitting diode module according to Embodiment 1. FIG. It is sectional drawing for demonstrating the example which mounts the light emitting diode module in Embodiment 2 in a package. It is sectional drawing for demonstrating the example which mounts the light emitting diode module in Embodiment 2 in a package provided with fluorescent substance. 6 is a side view for explaining a structural example of a light emitting diode module and a light traveling direction in Embodiment 2. FIG. 6 is a perspective view for explaining a structural example of a light emitting diode module according to Embodiment 2. FIG. It is the perspective view which turned down the condensing direction of the light emitting diode module of FIG. FIG. 6 is a cross-sectional view for explaining a first structural example of a light-emitting diode element in Embodiment 2 and a traveling direction of light. FIG. 10 is a cross-sectional view for explaining the first manufacturing method of the light-emitting diode element in the second embodiment. FIG. 11 is a cross-sectional view for explaining a second manufacturing method of the light-emitting diode element in the second embodiment. FIG. 6 is a cross-sectional view and a plan view for explaining a first structure example of a light-emitting diode element in a second embodiment. FIG. 33 is a plan view illustrating another structural example of the light-emitting diode element illustrated in FIG. 32. It is a figure for demonstrating the example which forms the light emitting diode module in Embodiment 2 on a wafer. FIG. 12 is a cross-sectional view for explaining another method (1) of forming the side reflecting portion (micromirror) in the second embodiment. FIG. 12 is a cross-sectional view for explaining another method (2) of forming the side reflecting portion (micromirror) in the second embodiment. It is sectional drawing for demonstrating another formation method (3) of the side reflection part (micromirror) in Embodiment 2. FIG. FIG. 10 is a cross-sectional view for explaining another structural example of the light-emitting diode element and the light traveling direction in the second embodiment. FIG. 10 is a cross-sectional view for explaining a third manufacturing method of the light-emitting diode element (side reflecting portion) in the second embodiment. It is sectional drawing for demonstrating the 4th manufacturing method of the light emitting diode element (side reflection part) in Embodiment 2. FIG. It is sectional drawing for demonstrating the advancing direction of the light in the light emitting diode element manufactured by the manufacturing method shown in FIG. It is sectional drawing for demonstrating the example which mounts the light emitting diode module in Embodiment 3 in a package. It is sectional drawing for demonstrating the example which mounts the light emitting diode module in Embodiment 3 in a package provided with fluorescent substance. 6 is a side view for explaining a structural example of a light-emitting diode module according to Embodiment 3. FIG. FIG. 45 is a perspective view of the light-emitting diode module shown in FIG. 44. FIG. 10 is a side view for explaining the light traveling direction of the light emitting diode module according to the third embodiment. 10A and 10B are a cross-sectional view and a plan view for explaining a structure example of a light-emitting diode element in Embodiment 3. FIG. 10 is a cross-sectional view for explaining a step of forming a side reflection portion (micromirror) of a light emitting diode element in Embodiment 3 on a wafer. It is a figure for demonstrating the relationship between the surface orientation of a silicon wafer, and an etching characteristic. It is sectional drawing for demonstrating the process bonded together with the 2nd board | substrate (silicon substrate) which formed the structure by the side of the transparent substrate of the light emitting diode element in Embodiment 3, and formed the side reflection part. FIG. 10 is a cross-sectional view for describing a step of forming an electrode structure of a light emitting diode element in a third embodiment. It is sectional drawing for demonstrating the advancing direction of the light in the light emitting diode element manufactured by the manufacturing method shown in FIG. FIG. 11 is a side view showing a state where a power supply wiring layer and a flip chip electrode are formed in the light emitting diode module according to Embodiment 3. It is sectional drawing for demonstrating the light emitting diode module comprised after a flip chip electrode is arrange | positioned on a power wiring layer, and a transparent substrate being removed. It is sectional drawing which bonded another wafer board | substrate with which the penetration conductive via was formed in the wafer state after the light emitting diode element and the power supply wiring layer were formed on the board | substrate. It is sectional drawing for demonstrating the structure of the conventional light emitting diode. It is sectional drawing for demonstrating the structure of another conventional light emitting diode. FIG. 58 is a plan view and a cross-sectional view for explaining a structure of a light emitting element provided in the light emitting diode of FIG. 57.

  The light-emitting diode element of the present invention is a light-emitting diode that takes out light emitted from a light-emitting layer formed on a substrate by a thin film in a direction perpendicular to the light-emitting layer, and is substantially parallel to the light-emitting layer (light emission). A structure for reflecting and extracting light emitted to the side of the layer). In the following, the direction of taking out the light emitted from the light emitting layer is referred to as the “light collecting direction”. The “side” is a direction perpendicular to the direction along the surface of the light emitting layer, that is, the light collecting direction. That is, the light emitted to the side means light emitted from the side surface of the light emitting layer.

  One of the gist of the present invention is to form a fine side reflecting portion on the side of the thin film as described above by using a semiconductor manufacturing technique. Therefore, hereinafter, the side reflection portion is referred to as a “micromirror”, and one light emitting diode element including a light emitting layer and a micromirror formed on a substrate is referred to as an “optical microcell”.

  The gist of the present invention is to provide a structure that allows the above-described optical microcells to be arranged on the same substrate. By forming a plurality of optical microcells on the same substrate and electrically connecting the optical microcells, one module including the plurality of optical microcells can be configured. This module is hereinafter referred to as “light-emitting diode module” or “optical micromodule”. The light emitting diode module (optical micromodule) can include an electrode and a power supply wiring layer that are integrally formed to supply power to each optical microcell that constitutes the light emitting diode module.

  2 and 3 schematically show the basic structure of the light-emitting diode element of the present invention. FIG. 2 is a cross-sectional view, and the light emitting diode element 10 is inclined at an angle α in a predetermined range with respect to the light emitting layer 4 in the vicinity of the light emitting layer 4 formed on the substrate 3 and the side surface 4s of the light emitting layer. A side reflector 6 is provided. The light emitting layer 4 is a thin film including semiconductor layers 4a and 4b and an active layer 4c formed between them to emit light, and the thickness of the light emitting layer 4 is about several μm.

The material of the substrate 3 is not particularly limited as long as a thin light emitting layer can be formed. For example, sapphire (Al ₂ O ₃ ), silicon (Si), silicon carbide (SiC), and the like can be given. Hereinafter, a substrate that transmits light emitted from the light emitting layer, such as a sapphire substrate, is referred to as a “transparent substrate”.
The light emitting layer 4 includes semiconductor layers 4a, 4b and 4c. Hereinafter, a light emitting diode that emits ultraviolet light using GaAlN as a material will be described as an example. For example, the semiconductor layer 4a is a P-type GaAlN semiconductor, and the semiconductor layer 4b is an N-type GaAlN semiconductor. A light emitting diode made of GaAlN is known to emit light in the green to ultraviolet range. In addition, there are various semiconductor materials such as GaN, InGaN, ZnSe, and ZnO as light emitting diode semiconductor materials. However, the present invention relates to a structure for collecting light emitted from a light emitting layer made of a semiconductor, and the material of the semiconductor and the structure of the light emitting layer are not particularly limited, and are emitted from the light emitting layer. The wavelength of light is also not limited. That is, the structure of the optical microcell and the optical micromodule of the present invention can be applied regardless of the material used for the light emitting layer and the light emission color.

The optical microcell 10 can include a back reflecting film 5 in a direction opposite to the light collecting direction z with respect to the light emitting layer 4. The back reflecting film 5 is a mirror that reflects light emitted from the light emitting layer 4 (active layer 42) in the direction opposite to the light collecting direction z in the light collecting direction z. In the optical microcell 10 shown in FIG. 2, the light emitting layer 4 and the side reflection part (micromirror) 6 are formed on the surface of the substrate 3 on the condensing direction z side. In this case, the back reflecting film 5 can be provided between the substrate 3 and the light emitting layer 4 as shown in FIG. When a transparent substrate is used as the substrate 3, a back reflecting film may be provided on the lower surface of the transparent substrate, that is, the surface opposite to the surface on which the light emitting layer 4 is formed.
The material of the back reflection film is not particularly limited as long as a thin film that reflects light can be formed. For example, aluminum, silver, nickel, chromium, cobalt, etc. are mentioned.

  As shown in FIG. 2, in the optical microcell 10, light emitted from the active layer 4c in the light collecting direction z can be extracted as it is (p). The light emitted from the active layer 4c in the direction opposite to the light collecting direction z is reflected by the back reflecting film 5 and extracted in the light collecting direction (q). Further, the light traveling from the side surface 4s of the light emitting layer in the direction S substantially parallel to the active layer along the active layer 4c is reflected by the micromirror 6 and extracted in a substantially condensing direction (r).

  As shown in FIG. 4, the optical microcell may have a structure in which a transparent substrate 31 is used and the light emitting layer 41 and the micromirror 61 are provided on the substrate surface opposite to the light collecting direction z. In the optical microcell 11, a back reflection film 51 is formed on the lower surface of the light emitting layer 41. The micromirror 61 can be formed simultaneously with the light emitting layer 41 on the surface of the transparent substrate 31. Further, the substrate may be composed of a transparent substrate and a second substrate. In this case, the optical microcell 11 can be configured by forming the light emitting layer 41 on the surface of the transparent substrate 31 and forming the micromirror 61 on the second substrate and bonding the two substrates together. In any case, the light emitted in each direction from the light emitting layer (active layer) can be extracted in the light condensing direction through the transparent substrate 31 (p, q, r).

The micromirror (6, 61) may be a surface of a structure (side wall portion) formed in the vicinity of the side surface of the light emitting layer or covering the side surface of the light emitting layer. That is, the micromirror can be configured by inclining the wall surface of the side wall portion facing the side surface of the light emitting layer at an angle α with respect to the active layer and using the surface of the wall surface as a light reflecting surface. As shown in the embodiment, the side wall portion may be formed of the same material as the material forming the light emitting layer (for example, GaAlN), or may be formed of a different material (for example, silicon, silicon oxide, or the like). Good. Further, in order to form the slope of the wall surface, a permeable membrane layer that transmits light emitted from the insulating layer or the light emitting layer can be provided. The material of the insulating layer or the permeable membrane layer is not limited, but for example, silicon oxide (SiO ₂ or the like) can be used. Further, the reflection surface may be the surface of the sidewall part itself, or a reflection film may be formed on the surface of the sidewall part. The material of the reflective film is not particularly limited as long as a thin film that reflects light can be formed. For example, aluminum, silver, nickel, chromium, cobalt, etc. are mentioned.

  FIG. 3 is a plan view of the light emitting diode element 10 as viewed from the light collecting direction z side. The light emitting layer 4 is formed in a certain region on the substrate 3, and is configured such that the micromirror 6 surrounds the periphery of the light emitting layer 4. The size of one optical microcell is not particularly limited. For example, one side can have a size of several tens to several hundreds of μm. Further, the width of the portion where the micromirror 6 is formed can be about several μm to several tens of μm.

The size of one optical microcell should be small in order to minimize the attenuation of light traveling in the direction along the light emitting layer (direction S shown in FIG. 2). This is because if the attenuation of light in the direction along the light emitting layer is small, the amount of collected light per current injected for light emission can be increased. In order to suppress attenuation of light emitted to the side of the light emitting layer, it is desirable that the space between the light emitting layer and the micromirror is narrow.
On the other hand, it is known that if the size of the light emitting layer is made too small, the area ratio of the interface increases and the light emission efficiency decreases. Further, since the micromirror and its peripheral portion do not directly contribute to light emission, the light emission amount is limited by the area of the micromirror peripheral portion and the presence of the micromirror itself. Therefore, in order to obtain a sufficient amount of light collection, the area of the light emitting layer must be increased.

  The aim of the present invention is to realize an energy efficient light emitting diode by maximizing the amount of collected light per injection current to the light emitting diode. Therefore, the size of the optical microcell needs to be optimized in relation to the size of the light emitting layer, the size of the micromirror part that does not contribute to light emission, the distance between the light emitting layer and the micromirror, and the like. Optimum conditions vary depending on the thickness of the light emitting layer and the light emitting material, but in any size of optical microcell, the light collection efficiency is maximized in units of optical microcells. The idea of maximizing the luminous efficiency of the optical micromodule is the same.

  Further, the present invention is characterized in that in one optical microcell, a micromirror that is opposed to the side surface of the light emitting layer and is inclined with respect to the light emitting layer can be formed in the vicinity of the side surface of the light emitting layer. It is said. Accordingly, the micromirror can be provided so as to surround the entire periphery in the side surface direction of the light emitting layer, or may be provided on a part of the entire periphery. In order to capture as much light emitted to the side of the light emitting layer as possible and collect it in the light collecting direction by the micromirror, the micromirror is preferably formed in most of the periphery of the light emitting layer, as shown in FIG. More preferably, the light emitting layer 4 is formed all around.

Next, the inclination angle α of the micromirror will be described.
In FIG. 5, the horizontal direction is the direction S parallel to the light emitting layer, the upward direction is the light collecting direction z, and the surface M is the reflecting surface of the micromirror. The light (in) emitted from the light emitting layer in the direction along the light emitting layer is reflected by the micromirror surface M in a substantially condensing direction (out).
As shown in FIG. 5A, when the tilt angle α of the micromirror is 45 °, the light reflected by the micromirror is most preferable because it goes in the light collecting direction z perpendicular to the light emitting layer. Further, as shown in FIGS. 4B and 4C, when the inclination angle α is 60 ° or 30 °, the light is reflected in a direction deviating 30 ° with respect to the light collecting direction z. In this case, the vector intensity of light in the condensing direction is about 1.73 / 2, and about 86% of the light intensity can be extracted in the condensing direction. Further, as shown in FIGS. 4D and 4E, when the inclination angle α is 67.5 ° or 22.5 °, the light is deviated by 45 ° with respect to the light collecting direction z. Reflect on. In this case, although the vector intensity of light in the condensing direction is about ½, about 50% of the light intensity can still be extracted in the condensing direction.
Therefore, the micromirror whose inclination angle α of the micromirror with respect to the light emitting layer is approximately 45 ° (for example, 22.5 ° to 67.5 °, preferably 30 ° to 60 °, most preferably 45 °). If it is formed, it becomes possible to take out the light of the intensity | strength according to the inclination angle to a condensing direction.

The reflection surface of the micromirror does not necessarily have to be a flat surface as a whole, and may be composed of a curved surface. As will be described later in Examples, the micromirror can be formed into various shapes by various manufacturing methods. However, in any case, it is a common configuration to direct light traveling in a direction substantially parallel to the light emitting layer in the light collecting direction by the micromirror.
The light traveling in a direction substantially parallel to the light emitting layer is refracted, reflected, scattered, etc. due to the difference in the refractive index of the structure and material inside the light emitting layer and between the light emitting layer and the micromirror. And each layer and surface irregularities are complicatedly affected. Therefore, in practice, the angle of inclination of the entire micromirror (from the bottom to the top) facing the side surface of the light emitting layer is in the range of 0 ° to 90 °, and the portion facing the active layer in the light emitting layer If the angle of inclination of the central portion of the reflecting surface with respect to is formed to be approximately 45 °, a light collecting effect can be obtained.

  A fluorescent material including a fluorescent material such as a fluorescent pigment or a fluorescent dye can be disposed above (in the light collecting direction) the optical microcell and the optical micromodule. When the phosphor is provided, the light emitted from the light emitting layer hits the fluorescent material directly or reflected, and the fluorescent material is excited to emit light having a longer wavelength. For this reason, in particular, when a phosphor is provided in the light collecting direction, the range in which light can be captured by the phosphor even if the direction of the light reflected by the micromirror is out of the light collecting direction. It suffices if light is reflected in the direction.

In addition, the optical microcell and the optical micromodule can be configured by integrally forming an electrode and power supply wiring for supplying power to the light emitting layer. The material used for the electrode and the power supply wiring is not particularly limited as long as it has conductivity, and for example, aluminum can be used. Further, indium oxide (ITO) or the like can be used as a transparent conductive film.
The electrode of the light emitting layer is formed by integrating the first conductive layer and the second conductive layer, which are electrically the same as or electrically connected to either the N-type semiconductor layer or the P-type semiconductor layer, with the light emitting layer. Can be formed. Hereinafter, an electrode (cathode) connected to the N-type semiconductor layer is referred to as an N-type electrode or N electrode, and an electrode (anode) connected to the P-type semiconductor layer is referred to as a P-type electrode or P electrode.
In the optical microcell and the optical micromodule, a power supply wiring layer for wiring to the electrodes can be integrally formed. In the power supply wiring layer, a first conductor electrically connected to the first conductive layer and a second conductor electrically connected to the second conductive layer are wired. The connection method between the optical microcell or optical micromodule and the outside (package substrate, main substrate, lead terminal, etc.) is not limited. For example, wire bonding may be performed, or by providing protruding electrodes (bumps) Flip chip mounting may be performed.

In order to perform flip chip mounting, the optical microcell and the optical micromodule are electrically connected to the first conductor when the light emitting layer is formed on the surface of the transparent substrate opposite to the light collecting direction. A flip chip electrode or flip chip electrode, and a flip chip electrode or flip chip electrode electrically connected to the second conductor. The shape of the flip chip electrode (bump) is not particularly limited, and may be, for example, a columnar shape, a spherical shape, a plate shape, or the like. The above-mentioned flip chip electrode refers to an electrode for flip chip mounting, and any shape such as a film shape or a flat plate shape may be used. Bumps may be provided on the flip chip electrodes, and the optical microcell or the optical micromodule is mounted on the package substrate provided with the bumps using the flip chip electrodes. You can also. The flip chip electrode or the like may be formed in a wafer state, or stud bumps may be formed after dividing the wafer into individual optical microcells or optical micromodules.
When the light emitting layer is formed on the surface of the transparent substrate opposite to the light collecting direction, the optical microcell and the optical micromodule have a structure (light emitting layer, micromirror, power supply wiring layer) formed on the transparent substrate. , Flip chip electrodes, etc.) may be physically fixed, and then the transparent substrate may be removed (lifted off). That is, after the flip chip electrode or the like is disposed on the power wiring layer of the optical microcell or optical micromodule, the transparent substrate can be removed. For example, as described in the embodiments, the transparent substrate can be removed after the optical microcell or the optical micromodule is mounted on another wafer substrate, a package substrate, or the like.
Further, the exposed surface on the light emitting layer side after the transparent substrate is removed can be processed into a textured surface by blasting or the like. Here, the term “null” means that the surface is evenly presented so that the light inside the light emitting layer is not totally reflected on the surface.

  Further, the optical microcell and the optical micromodule can be mounted on a package in the same manner as shown in FIG. The optical microcell and the optical micromodule can also be mounted on a known package (for example, see FIGS. 56 and 57). A phosphor can be provided in the package. When visible light is emitted from the light emitting layer of the optical microcell and the visible light is used as it is, a phosphor is unnecessary.

(Embodiment 1)
An optical microcell and an optical micromodule can be configured by forming the light emitting layer and the micromirror on the surface of the substrate on the light collecting direction side.
An example of the layout of the optical micromodule is shown in the plan view of FIG. In this example, the optical micromodule 201 includes 24 elements (cells) arranged in a matrix of 6 rows and 4 columns on one substrate. Among these, the cells C _{1 to} C ₂₂ excluding the P electrode portion 701a and the N electrode portion 701b are optical microcells.

  FIG. 7 is a plan view of one optical microcell constituting the optical micromodule 201. As described above, the optical microcell includes a semiconductor layer (for example, GaAlN) formed on a substrate, a micromirror, and the like. In FIG. 7, the semiconductor layer is formed in a boundary 4010 on the substrate, and a P-type (for example, P-type GaAlN) region and an N-type (for example, N-type GaAlN) region are separated by a boundary 4011. . A micromirror 61 is provided so as to surround the region 4010 of the semiconductor layer. A wiring region 7010 on the substrate in the boundary region of the optical microcell is a space used for wiring from the P electrode and the N electrode, and is positioned so as not to block light emitted from the optical microcell. Is provided.

6, for example, optical microcell _{C 11} includes a P-type region 401a, an N-type region 401b. In the optical microcells C ₁₁ , C _12, and C ₂₂ arranged in the horizontal direction, a wiring 761a is formed using the same wiring material (for example, Al) as the P electrode 701a. Further, the N electrode 701b and the N-type region of each optical microcell are connected by the same wiring (761b or the like). These wirings can be performed using the wiring region 7010 of the optical microcell. Thereby, the light emitted from the light emitting layer and the optical micromirror part can be prevented from being blocked by the wiring.
In addition, the P-type regions of the optical microcells arranged in a column are connected to each other by a transparent conductive film 7613. Even while the P electrode 701a and the P-type region of the optical micro cell _{C 1,} are connected by a transparent conductive film 7614.

FIG. 8 shows details of the optical microcells C ₄ , C ₅ , C ₆ , and C ₇ . The P-type regions of the optical microcell C ₄ and the optical microcell C _{5 and} the P-type regions of the optical microcell C ₆ and the optical microcell C ₇ are connected by a transparent conductive film 7613. The N-type regions of each optical microcell are connected by a wiring layer 761b using Al or the like.
FIG. 9A shows the connection between the N electrode 701b and the N-type region 401b of the optical microcell _C18 . Both are connected by a wiring layer 761b using Al or the like. Further, FIG. 9 (b) shows a state in which the P-type region 401a of the P electrode 701a and the light microcells _{C 1,} connected by a transparent conductive film 7614.

  As described above, in the optical micromodule 201, the P-type regions and the N-type regions of each optical microcell are connected in common. Therefore, the optical micromodule 201 constitutes one light emitting diode module (optical micromodule) represented by the equivalent circuit diagram of FIG.

  The optical microcell constituting the optical micromodule 201 will be described based on a specific embodiment. In this example, a structure (side wall part) is made of the same material as that of the light emitting layer on the periphery of the light emitting layer on one substrate, an inclined wall surface is formed on the side wall part, and the inclined wall surface is made of silver or nickel. A micromirror is formed by covering with a reflective film made of a film or the like. Thereby, the micromirror inclined with respect to the light emitting layer can be formed all around or part of the light emitting layer. Further, a back reflecting film is provided on the back surface of the light emitting layer as viewed from the light collecting direction.

FIG. 11 is a cross-sectional view showing the structure of the optical microcell 102 (corresponding to the YY ′ cross section of the optical microcell shown in FIG. 7). In the optical microcell 102, a light emitting layer 402 including an N-type GaAlN semiconductor layer 402b, an active layer 402c, and a P-type GaAlN semiconductor layer 402a is formed on a sapphire substrate 302. In the vicinity of the side surface of the light emitting layer, a side wall portion made of the same GaAlN semiconductor as the light emitting layer and processed so that the side surface 6021 facing the light emitting layer is inclined is formed. The side wall portion can be processed simultaneously with the light emitting layer. The side wall portion is covered with a thin film 6022 using silver, nickel, or the like. Furthermore, an insulating layer 562 made of SiO ₂ or the like and a transparent electrode layer (P-type electrode portion 702a, N-type electrode portion 702b) made of indium oxide or the like are formed on the semiconductor layer. A back reflection film 502 is formed on the back surface of the sapphire substrate 302.
The thin film layer 6022 becomes a reflective film of the micromirror 602, and light in the direction along the active layer 402c is reflected by the micromirror 602 provided in the vicinity of the side surface and emitted in the light collecting direction.

12 is a cross-sectional view of another portion of the optical microcell 102 (corresponding to the Y ₂ -Y ₂ ′ cross section of the optical microcell shown in FIG. 7). Except that the N-type electrode portion 702b is not formed in this portion, it is the same as the structure and operation described with reference to FIG.

FIG. 13 is a cross-sectional view of an optical micromodule configured by arranging the optical microcells 102. This corresponds to the XX ′ cross section of the optical micromodule 201 shown in FIG. 6, and each optical microcell corresponds to the optical microcells C ₁₈ , C ₁₆ , C ₇ , and C ₄ in FIG. 6 in order from the left. Micromirrors 602 are formed on both sides of the light emitting layer of each optical microcell.
In FIG. 13, p, q, r, and r ′ indicate the traveling directions of light emitted from the active layer. For example, light emitted upward from the active layer of the optical microcell C ₁₆ , that is, in the light collecting direction z, travels as it is (p). The light emitted from the active layer in the direction opposite to the light collecting direction z is reflected by the back reflecting film 502 and emitted in the light collecting direction (q). The light emitted to the right side of the drawing in the direction along the active layer is reflected by the right micromirror 602 and is emitted in a substantially condensing direction (r). Of the light along the active layer, the light emitted to the left side (N-type region) in the figure is also reflected by the left micromirror 602 through the inside of the N-type semiconductor layer 402b, the transparent electrode 702b, etc. Heading in the direction of light collection (r ′).
The light emitted directly or reflected in the light collecting direction z as described above excites light having a long wavelength by disposing a phosphor (not shown) in the light collecting direction above the optical microcell. Thus, white light can be obtained by the combination of the lights.

The optical microcell 102 (or the optical micromodule 201) can be manufactured, for example, by a manufacturing method as shown in FIG.
14A shows a step of forming a semiconductor layer including a N-type GaAlN semiconductor 402b, an active layer 402c, and a P-type GaAlN semiconductor 402a on a sapphire substrate 302 (substrate manufacturing process), and then a semiconductor layer is formed thereon. A state in which a photoresist 1611 for etching is formed is shown.
FIG. 14B shows a state in which a pattern of a photoresist 1612 for further processing is formed after the step of dry etching the semiconductor layers 402b, 402c and 402a (semiconductor layer etching step). By the semiconductor layer etching process, the semiconductor layer is formed as indicated by the interface 4021.
FIG. 14C shows a state in which the inclined surface 4022 is formed in the semiconductor layer by an etching process (taper etching process) in which the portion of the interface 4021 of the semiconductor layer is inclined. The slope 4022 can be formed by wet etching using a photoresist 1612. After the etching process, the photoresist is removed.

FIG. 14D shows a process of forming a reflective film on the inclined surface 4022 (side reflective film forming process). After depositing a thin film 6023 of silver or nickel, a photoresist is applied, and the pattern of the photoresist is formed. 1613 is formed. Thereafter, the thin film 6023 is etched to form a micromirror (602). In order to adjust the shape of the inclined portion of the micromirror, the thin film 6023 is etched by wet etching. This process is further illustrated in FIG. After the etching process, the photoresist is removed.
FIG. 14E shows a state in which a photoresist pattern 1614 is formed in order to expose the N-type semiconductor portion after the micromirror 602 is formed in the side reflection film forming step.
FIG. 14F shows a state in which the step of removing the P-type semiconductor portion and the active layer (P-type semiconductor etching step) is performed. After removing the P-type layer 402a and the active layer 402c of the GaAlN semiconductor by etching to expose the N-type layer 402b, the photoresist is removed. The removal of the P-type region and the active layer of the GaAlN semiconductor can be performed using a known method that utilizes the management of the etching time or changes in the etching rate of the N-type semiconductor layer. As a result, the surface 4025 of the N-type semiconductor and the surface 4024 of the P-type semiconductor are exposed.

FIG. 14G shows a state in which after forming a silicon oxide film layer on the entire surface, a step of forming an opening for an electrode by etching (protective film forming step) is performed, and the photoresist is removed. . By this step, a silicon oxide film 561 for insulation and protection, a contact portion 4026 for the P-type electrode, and a contact portion 4027 for the N-type electrode are formed.
In FIG. 14 (h), after forming a transparent conductive film such as indium oxide (ITO) over the entire surface, an etching process is performed to form an indium oxide film on the electrode (electrode formation process), and then the photoresist is removed. Shows the state. By this step, a P-type electrode portion 702a and an N-type electrode portion 702b are formed. Further, as shown in FIG. 14 (h), the back reflection film 502 is formed by evaporating silver or the like on the back surface of the sapphire substrate 302 in the final process (back reflection film forming process).

  In the side reflection film forming step (see FIG. 14D), a method of wet etching the thin film 6023 in order to adjust the shape of the inclined portion of the micromirror (602) will be described in more detail. As shown in FIG. 14D, the positional relationship between the end surface of the photoresist 1613 provided in the micromirror portion and the inclined portion of the thin film 6023 formed of silver, nickel or the like is important. By performing wet etching in this state, as shown in FIG. 15, the thin film 6023 is etched while the photoresist 1613 is peeled off from the end face in contact with the thin film 6023 at the bottom skirt. As a result, an underetched portion 6024 is formed. As a result, the inclined surface of the thin film 6023 has a gentle shape up to the sapphire substrate surface. Thereafter, if the P-type semiconductor etching step is performed after removing the photoresist, the micromirror 602 having a gentle shape with the inclined surface as shown in FIG. 14F can be formed.

FIG. 16 shows how the light emitted from the light emitting layer (active layer) is reflected by the micromirror and the back reflecting film in the optical microcell formed by the above process. In this figure, the light emitted from the active layer in the surface direction (condensing direction z) is emitted as it is (p). The light emitted from the active layer in the back surface direction is reflected in the light collecting direction by the back reflection film (q). Light emitted from the active layer in a direction substantially parallel to the active layer is reflected by the micromirror 602 and emitted toward the surface (r ₁ , r ₂ , r ₃ , r ₄ ). Among these, r ₁ and r ₄ indicate light substantially parallel to the active layer, and r ₂ indicates light in a slightly oblique direction. r ₃ indicates a light that has transmitted while being totally reflected, such as a semiconductor layer, shows a state released to substantially condensing direction is reflected by the micromirror.
The light emitted from the light emitting layer is slightly refracted due to the difference in refractive index at the interface with the silicon oxide film, the transparent conductive film or the like, but is not shown in the figure because it is explained mainly by reflection. Similarly, it is refracted when the reflected light comes out of the silicon oxide film or the like into the atmosphere, but it is not shown. The existence of refraction does not change the principle of reflection by the micromirror surface.

The optical microcell can also be configured using an opaque silicon substrate or the like as the substrate. FIG. 17 shows a cross-sectional structure of an optical microcell 103 using a silicon substrate, which is different from the optical microcell 102. Note that a description of points common to the above-described structure example of the optical microcell will be omitted. In this example, a low-cost silicon substrate is used as the substrate, and a back reflective film is provided on the lower surface of the light emitting layer (GaAlN layer).
In this case, the YY ′ cross section of one optical microcell shown in FIG. 7 can have a structure as shown in FIG. The optical microcell 103 includes a conductive thin film 503 that reflects light, such as a nickel thin film, a chromium thin film, or a silver thin film, on a silicon substrate 303. A light emitting layer 403 including an N-type GaAlN semiconductor layer 403b and a P-type GaAlN semiconductor layer 403a is formed on the conductive thin film. An active layer 403c is present at the interface between the N-type GaAlN semiconductor 403b and the P-type GaAlN semiconductor 403a (not shown because it is a thin layer). In the vicinity of the side surface of the light emitting layer 403, a side wall portion is formed that is made of the same GaAlN semiconductor as the light emitting layer and is processed by inclining the side surface 6031 facing the light emitting layer. The side wall portion can be formed simultaneously with the light emitting layer. The side wall is covered with a thin film layer 6032 using silver, nickel or the like. Furthermore, an insulating layer 563 made of SiO ₂ or the like and a transparent electrode layer (P-type electrode portion 703a or N-type electrode portion 703b) made of indium oxide or the like are formed on the semiconductor layer.
The thin film layer 6032 becomes a reflective film of the micromirror 603, and light in the direction along the active layer is reflected by the micromirrors 603 provided on both sides of the light emitting layer 403 and is emitted in a substantially condensing direction.

18 is a Y ₂ -Y ₂ ′ sectional view of the optical microcell shown in FIG. 7. Except that the N-type electrode portion 703b is not formed in this portion on the optical microcell, the structure and the operation are the same as those in the YY ′ cross section, and the light in the direction along the light emitting layer 403 emits light. The light is reflected by the micromirrors 603 provided on both sides of the layer and emitted in a substantially condensing direction.

  In the structure of the optical microcell 103 shown in FIG. 17 and FIG. 18, light in the back surface direction from the active layer is reflected by the reflective film layer 503 directly below, so that it is compared with the case of the optical microcell 102 shown in FIG. Thus, attenuation due to the reciprocation of light on the sapphire substrate is improved. In the vicinity of the active layer, since it is surrounded by a reflective film layer in the back direction and micromirrors in the side direction, it is extremely preferable as a reflective structure built in the optical microcell. Further, when the back reflection film layer 503 and the micromirror 603 are arranged close to each other, the periphery of the light emitting layer 403 can be covered with a reflection film except for the light collection direction, and the light collection rate can be ideally increased. This can be achieved by shortening the distance between the reflective film layer 503 and the micromirror 603 in FIGS.

FIG. 19 is a cross-sectional view of an optical micromodule configured by arranging the optical microcells 103. This corresponds to the XX ′ cross section of the optical micromodule 201 shown in FIG. 6, and each optical microcell corresponds to the optical microcells C ₁₈ , C ₁₆ , C ₇ , and C ₄ in FIG. 6 in order from the left. Micromirrors 603 are formed on both sides of the light emitting layer of each optical microcell.
In FIG. 19, p, q, r, and r ′ indicate the traveling directions of light emitted from the active layer. Since the optical microcell 103 includes the back reflecting film 503 on the silicon substrate 303, the light emitted from the active layer in the direction opposite to the collecting direction z is reflected by the back reflecting film 503 and collected. (Q). Except for this point, the optical path is the same as the case of the optical microcell 102 (FIG. 13).
Light emitted directly or reflected from the active layer in the light collecting direction z excites light with a long wavelength by arranging a phosphor (not shown) above the light microcell (light collecting direction). Thus, white light can be obtained by the combination of the lights.

The optical microcell 103 (optical micromodule 201) can be manufactured, for example, by a manufacturing method as shown in FIG.
FIG. 20A illustrates a step (substrate manufacturing step) of forming a semiconductor layer including a conductive thin film 503 of nickel, chromium, silver, or the like, an N-type GaAlN semiconductor 403b, and a P-type GaAlN semiconductor 403a on a silicon substrate 303. This represents a state in which a photoresist 1621 is provided thereon. An active layer 403c (not shown) is formed at the interface between the N-type GaAlN semiconductor 403b and the P-type GaAlN semiconductor 403a. The photoresist 1621 is for etching the semiconductor layer and the conductive thin film 503.
Thereafter, the semiconductor layer etching step (FIG. 14) for dry etching the semiconductor layer and the conductive thin film 503 is performed in the same manner as in the case of the optical microcell 102 (FIG. 14) except that the conductive thin film 503 is formed on the lower surface of the semiconductor layer. 20 (b)), a taper etching step (FIG. 20 (c)) for forming the slope 4035 by a wet etching method, and a side reflection film forming step for forming a micromirror 603 by taper etching after forming a silver or nickel thin film 6033. (FIG. 20D) is performed. Thereafter, a photoresist for forming the next N-type electrode portion is applied to form a photoresist pattern 1624 (FIG. 20E).

FIG. 20 (f) shows a state in which a semiconductor part etching process for removing the semiconductor part by etching the GaAlN semiconductor is performed. Thereby, the surface 5031 of the metal thin film is exposed. Etching management is easy because the metal thin film serves as a stopper for etching the GaAlN semiconductor. A surface 5031 where the metal thin film is exposed is an N-type electrode portion, and an exposed surface 4036 of the P-type semiconductor is a P-type electrode portion.
FIG. 20G shows a process in which after forming the silicon oxide film layer, an opening for the electrode is formed by etching (protective film forming process), and then the photoresist is removed. By this process, a silicon oxide film 563 as a protection portion, a contact portion 4037 for a P-type electrode, and a contact portion 5032 for an N-type electrode are formed.
FIG. 20H shows a process in which a transparent conductive film such as indium oxide (ITO) is formed on the entire surface, an indium oxide film is formed on the electrode portion by an etching technique (electrode formation process), and then the photoresist is removed. Show. A P-type electrode portion 703a and an N-type electrode portion 703b are formed. The back reflecting film (conductive thin film) 503 is formed on the silicon substrate 303.

  In addition, the manufacturing process of the wafer used as a substrate shown in FIG. 20A includes, for example, a P-type GaAlN semiconductor formed on another sapphire substrate, an active layer, a nickel thin film deposited on a silicon substrate, This is also possible by a method of transferring an N-type GaAlN semiconductor or a nickel thin film layer. Since the present invention relates to the formation of micromirrors and optical microcells, the substrate forming method is not mentioned.

The micromirror part of the optical microcell 103 shown in FIGS. 17 and 18 may have a structure provided with a depression (dip part) as shown in FIGS. The optical microcell 104 provided with the dip portion is the same as the structure of the optical microcell 103 except that a recess is formed in the micromirror portion. The cross section shown in FIG. 21 corresponds to the YY ′ cross section of the optical microcell shown in FIG. The cross section shown in FIG. 22 corresponds to the Y ₂ -Y ₂ ′ cross section of the optical microcell shown in FIG.
The optical microcell 104 shown in FIG. 21 includes a conductive thin film 504 that reflects light, such as a nickel thin film or a chromium thin film, an N-type GaAlN semiconductor layer 404b, and a P-type GaAlN semiconductor layer 404a on a silicon substrate 304. A light emitting layer 404 is formed. An active layer 404c is present at the interface between the N-type GaAlN semiconductor 404b and the P-type GaAlN semiconductor 404a (not shown). In the vicinity of the side surface of the light emitting layer 404, a side wall portion is formed which is made of the same GaAlN semiconductor as the light emitting layer with the dip portion 6043 interposed therebetween and is processed by inclining the side surface 6041 facing the light emitting layer. The dip portion 6043 is a recess formed in the silicon substrate to adjust the shape of the micromirror. The side wall portion can be formed simultaneously with the light emitting layer. The side wall is covered with a thin film 6042 using silver, nickel, or the like. Further, an insulating layer 564 made of SiO ₂ or the like and a transparent electrode layer (P-type electrode portion 704a, N-type electrode portion 704b) made of indium oxide or the like are formed on the semiconductor layer.
The thin film layer 6042 becomes a reflective film of the micromirror 604, and light in the direction along the light emitting layer 404 is reflected by the micromirror 604 provided in the vicinity of the side surface and emitted in a substantially condensing direction.
The cross section of the optical microcell 104 shown in FIG. 22 is the same as the structure and operation shown in FIG. 21 except that the N-type electrode portion 704b is not formed.
The cross-sectional structure of the optical micromodule configured by arranging the optical microcells 104 (corresponding to the XX ′ cross section of the optical micromodule 201 shown in FIG. 6) is that a recess is formed in the micromirror part. This is the same as when the optical microcells 103 are arranged (FIG. 19).

  In the structure of the optical microcell 104 shown in FIGS. 21 and 22, light in the back surface direction from the active layer is reflected by the reflective film 504 directly below, so that it is compared with the case of the optical microcell 102 shown in FIG. The attenuation due to the reciprocation of light on the sapphire substrate is improved. In the vicinity of the active layer, since it is surrounded by a reflective film layer in the back direction and micromirrors in the side direction, it is extremely preferable as a reflective structure built in the optical microcell. Further, if the layout is such that the reflective film layer 504 and the micromirror 604 are close to each other, the periphery of the light emitting layer 404 can be covered with the reflective film except for the light collecting direction, and the light collecting rate can be ideally increased. This can be achieved by shortening the distance between the reflective film 504 and the micromirror 604 in FIGS.

FIG. 23 shows a manufacturing process of the optical microcell 104 (optical micromodule 201).
FIG. 23A shows a step of forming a conductive reflective film 504 made of nickel, chromium, silver, or the like, an N-type GaAlN semiconductor layer 404b, and a P-type GaAlN semiconductor layer 404a on a silicon substrate 304 (substrate manufacturing process). A state in which a photoresist 1631 is provided thereon is shown. An active layer 404c (not shown) is formed at the interface between the N-type GaAlN semiconductor 404b and the P-type GaAlN semiconductor 404a. The photoresist 1631 is for etching the semiconductor layer and the conductive thin film 504.
Thereafter, as in the case of the optical microcell 103 (FIG. 20), the semiconductor layer etching step (FIG. 23B) for dry etching the semiconductor layer and the conductive thin film, and the taper etching for forming the slope 4045 by the wet etching method. A process (FIG. 23C) is performed.

FIG. 23D shows a step of forming a dip portion 6042 on the silicon substrate 304 by using an etching technique utilizing the anisotropy of silicon after etching using a photoresist or a semiconductor layer as a mask (silicon substrate taper). The state of performing the etching step) is shown. For example, it is a well-known technique in the field of manufacturing micromachines using silicon that a silicon substrate having a 110-plane orientation can be etched with a potassium hydroxide solution to form a taper with an angle of 54 °. Thereby, a dip portion 6042 having a stable shape can be formed. After processing, the photoresist is removed.
FIG. 23E shows a state in which a photoresist pattern is formed by applying a photoresist 1633 after vapor-depositing a thin film 6043 of silver, nickel, chromium or the like on the entire surface. From this state, the micromirror (604) is formed by taper-etching the thin film 6043 (side reflection film forming step). Since the shape of the dip portion 6042 is stably formed, a micromirror having a preferable shape can be formed on a slope formed over the silicon substrate and the semiconductor layer.

FIG. 23 (f) shows a state in which a pattern is formed by forming a micromirror 604 by the side reflection film forming step and then applying a photoresist 1634 for forming an N-type electrode portion.
FIG. 23G shows a state in which a GaAlN semiconductor is etched to expose the thin film surface 5041 (semiconductor layer etching process). By selecting a material for etching the GaAlN semiconductor, such as nickel, which does not etch the material of the thin film 504 or a material having a low etching rate, the thin film 504 can be easily exposed. By this step, the surface 5041 of the thin film 504 and the surface 4045 of the P-type semiconductor are exposed.
FIG. 23 (h) shows a state in which a silicon oxide film layer is formed on the above structure and then a step of forming an opening for the electrode (protective film forming step) is performed by a photoetching technique. By this step, a protective portion 564 made of a silicon oxide film, a contact portion 4047 for the P-type electrode, and a contact portion 5042 for the N-type electrode are formed.
Thereafter, a transparent conductive film such as an indium oxide film is formed on the entire surface, and a process (electrode formation process) of forming a transparent conductive film such as indium oxide only on the electrode portion by a photoetching technique is performed. Thus, the optical microcell 104 shown in FIGS. 21 and 22 is completed. A back reflection film 504 is formed on the silicon substrate 304.

(Embodiment 2)
As shown in FIG. 4, the optical microcell and the optical micromodule of the present invention use a transparent substrate as the substrate, and form the light emitting layer on the surface of the transparent substrate opposite to the light collecting direction. It can also be configured. In this case, for example, a light-transmitting film layer that transmits light emitted from the light emitting layer and covers at least the side surface of the light emitting layer is formed. The permeable membrane layer can be formed with a thickness inclined so as to be thick on the substrate side and thin toward the opposite side. And a micromirror can be comprised by forming a reflecting film in the outer surface of the permeation | transmission film | membrane layer.

FIG. 24 is a cross-sectional view showing an example in which the optical micromodule is mounted on a package. The light collecting direction z is above the package in the figure.
In FIG. 24, an optical micromodule 231 is housed in a package including a protective transparent cap 971 and a package substrate 941. In the optical micromodule 231, an N-type semiconductor layer 431 b, an active layer 431 c, and a P-type semiconductor layer 431 a are formed on the lower surface (surface opposite to the light collection direction z) of a transparent substrate 331 (for example, a sapphire substrate). A light emitting layer 431 is provided, and a back reflecting film 531 is provided on the lower surface of the light emitting layer with an insulating layer interposed therebetween. Further, on the side surface side of the light emitting layer 431, a micromirror 631 inclined with a predetermined range of angle with respect to the active layer is formed.
The micromirror 631 can be formed so as to surround the side surface of the light emitting layer 431. As described above, one unit including one light emitting layer and a micromirror surrounding the side is called an optical microcell. In the cross section of the optical micromodule 231 shown in FIG. 24, the cross sections of two optical microcells are visible.
Of the light emitted from the active layer 431 c included in the optical micromodule 231, the light emitted toward the transparent substrate 331 side, that is, in the light collecting direction z, is emitted through the transparent substrate 331 in the light collecting direction. Light emitted from the active layer to the side opposite to the transparent substrate 331 is reflected by the back reflecting film 531 and is emitted through the transparent substrate 331 in the light collecting direction. Light emitted from the active layer in the side surface direction (a direction perpendicular to the light collecting direction z) is reflected by the micromirror 631 and is emitted through the transparent substrate 331 in a substantially light collecting direction. The relationship between the inclination angle α of the micromirror with respect to the active layer and the light reflection direction is as described above (see FIG. 5).

  The optical micromodule can include an electrode for supplying power to each light emitting layer, power supply wiring, and the like. In FIG. 24, the electrodes of the optical micromodule 231 are installed on the side opposite to the light collecting direction z and wired in the power supply wiring layer 771. Then, the power source is concentrated on the flip chip electrode 801, and is electrically connected to the lead 851 through this. The lead 851 is drawn out of the package substrate 941 and used for external connection.

  FIG. 25 shows a case where a phosphor 901 containing a phosphor is provided on the light collecting direction side from the optical micromodule 231. Similarly to FIG. 24, the optical micromodule 231 is mounted on the package substrate 942 via the flip chip electrode 802. A phosphor 901 is filled in a cap 972 having a reflecting portion whose inner surface is inclined, and the whole is sealed with a transparent cap 983. As described above, the light emitted from the active layer included in the optical micromodule 231 is collected in the light collecting direction z and excites the fluorescent material contained in the phosphor 901. Most of the light emitted by the fluorescent material is directly emitted in the light collecting direction z, and the light scattered in the package is reflected by the inclined side surface inside the cap 972 and collected in the light collecting direction.

Next, an example of an optical micromodule configured by arranging optical microcells similar to the above in a matrix will be described.
26 and 27 are a side view and a perspective view of the optical micromodule 232. In both figures, the light collection direction z is shown upward. The optical micromodule 232 includes an optical microcell layer 132 in which a light emitting layer and a micromirror are arranged on the lower surface of one sapphire substrate 332. In the optical microcell layer 132, a large number of optical microcells 1321 having a light emitting layer are formed side by side, and micromirrors 632 are provided at both ends of each optical microcell 1321. One optical microcell 1321 can be formed so that the four directions on the side surface of the light emitting layer are surrounded by the micromirror 632. A back reflection film 532 is provided on the lower surface of the optical microcell layer 132.

As shown in FIG. 26, among the light emitted from the light emitting layer in the optical microcell, the light directed in the light collecting direction z travels straight in the light collecting direction through the transparent substrate 332 (p). The light emitted in the direction opposite to the light collecting direction z is reflected by the back reflecting film 532 and collected in the light collecting direction through the transparent substrate 332 (q). Further, light in a direction perpendicular to the light collecting direction z is reflected in a substantially light collecting direction by a micromirror 632 formed around the side surface of the light emitting layer and inclined at an angle of about 45 ° with respect to the light emitting layer. Then, they are collected in a substantially condensing direction through the transparent substrate 332 (r). The light perpendicular to the condensing direction z propagates along the thin film of the light emitting layer. In order to avoid attenuation during propagation, it is preferable that the size of the light emitting layer is as small as possible, the area occupied by the micromirror in the optical microcell is as small as possible, and the distance between the light emitting layer and the micromirror is as short as possible. When the optical microcells are arranged, the size of each optical microcell, that is, the pitch of the micromirrors can be formed with a width and a depth of about 100 μm, for example.
Further, a power wiring layer 772 and a flip chip layer 802 for supplying power to each optical microcell are provided under the back reflecting film 532. Electrodes for supplying power to the light emitting layer of each optical microcell are wired in the power wiring layer 772 and are electrically connected so as to be integrated into the flip chip electrode 802. The flip chip electrode 802 is provided on the side opposite to the light collecting direction so as not to interfere with light collecting.

As shown in FIG. 27, nine micromirrors 632 are provided on one side of the optical micromodule 232, and eight optical microcells 1321 sandwiched between the micromirrors 632 are arranged. That, is represented the S _A surface S _B 8 pieces each surface of the optical micro-cell, the optical micromodule 232 will be composed of 8 × 8 = 64 pieces of light microcells.
FIG. 28 is a perspective view showing the optical micromodule 232 shown in FIG. 27 with the condensing direction z facing downward. As described above, power to the 64 optical microcells is supplied from the flip chip electrode 802 via the power supply wiring layer 772.

An example of a cross-sectional structure of an optical microcell constituting the optical micromodule 232 is shown in FIG. The optical microcell 133 includes a light emitting layer 433 including a transparent electrode layer 733, an N-type GaAlN layer 433b, an active layer 433c, and a P-type GaAlN layer 433a on a lower surface of a sapphire substrate 333, a conductor film (back reflecting film) 533, A silicon oxide film 573, a P-type electrode 733a, and an N-type electrode 733b are provided. The P-type electrode and the N-type electrode are formed of a material that reflects light, such as Al. The silicon oxide film 573 covers the light emitting layer 433, and the N-type electrode 733b formed on the silicon oxide film functions as a micromirror.
As shown in the drawing, among the light emitted from the active layer 433c in the light emitting layer, the light emitted in the light collecting direction z passes straight through the sapphire substrate 333 in the light collecting direction (p). The light emitted in the direction opposite to the light collecting direction z is reflected by the back reflecting film 533 and passes through the sapphire substrate 333 and gathers in the light collecting direction (q). Further, the light emitted along the direction perpendicular to the condensing direction, that is, along the active layer, is reflected by the micromirror (N-type electrode 733b) and gathers in the substantially condensing direction (r).

An example of a method for manufacturing the optical microcell 133 will be described with reference to FIG.
FIG. 30A shows a transparent electrode layer 7331 such as indium oxide (ITO), an N-type GaAlN layer 433b, an active layer 433c, a P-type GaAlN layer 433a, and a reflective conductor film 533 on a 3 inch sapphire substrate 333, for example. They are stacked in order. The substrate thus laminated is formed by forming a P-type GaAlN semiconductor layer, an active layer, an N-type GaAlN semiconductor layer, and an indium oxide film on a sapphire substrate, and transferring them onto a sapphire substrate 333 serving as a base material. It may be realized by a method.
In FIG. 30B, the transparent conductive film 533, the P-type GaAlN layer 433a, the active layer 433c, and the N-type GaAlN layer 433b are removed with the width of 20 μm and the pitch of about 100 μm, for example, leaving the transparent electrode 7331 on the substrate. State. This can be formed by photolithography and etching processes. In this case, ITO serves as an etching stopper.
FIG. 30C shows a state where the silicon oxide film 573 is deposited on the entire surface. The silicon oxide film is doped with high-concentration phosphorus so that a sloped wall surface can be easily provided by subsequent processing.

FIG. 30D shows a case where the silicon oxide film 573 is semi-melted at a relatively low temperature to form a gradient in film thickness. That is, the silicon oxide film covering the side surface of the semiconductor layer (light emitting layer) is formed so as to be inclined so that it is thick on the substrate 333 side and thins upward. It is a well-known technique for processing a silicon semiconductor that the silicon oxide film contains phosphorus at a high concentration and is semi-melted at a low temperature of several hundred degrees to have a slope.
FIG. 30E is a view in which an opening (contact portion) for taking out an electrode is provided by etching the silicon oxide film 573.
FIG. 30F shows a state in which an Al thin film is deposited on the entire surface in the above state, and then the Al thin film is etched to form a P-type electrode 733a and an N-type electrode 733b.

In addition, a structure similar to that of the optical microcell 133 can be realized by another process. The steps shown in FIGS. 30A to 30D are the same. Thereafter, an example in which an opening (contact part) for extracting an electrode is provided in the silicon oxide film by using a taper etching method is shown in FIGS. As a result, the shape of the micromirror can be further smoothed.
In FIG. 31A, after performing the steps shown in FIGS. 30A to 30D, a photoresist 1711 is formed to form an opening (contact portion) for extracting an electrode in the silicon oxide film 573. It is a figure showing the state which carried out.
FIG. 31B shows a case where the thickness of the silicon oxide film is intentionally gently inclined by the step of taper etching the silicon oxide film 573 in the above state. In the taper etching, the adhesiveness between the photoresist and the silicon oxide film is intentionally sparse, and the lateral etching in the figure is promoted. This is a known technique for rounding the shape of the film after etching.
FIG. 31C shows a case where an Al thin film is deposited on the entire surface after the above process, and then the Al thin film is etched to form a P-type electrode 733a and an N-type electrode 733b. The N-type electrode 733b also serves as a micromirror. Since the electrode material becomes a material component of the micromirror, it is preferable that the electrode has a laminated structure containing chromium, nickel, silver or the like rather than simply using an aluminum material. For example, a structure in which a thin chrome, nickel, or silver layer is provided for the role of a micromirror and an aluminum layer is provided thereon can be used.

FIG. 32 shows a cross section of the optical microcell 133 manufactured by the process shown in FIG. 30 and a plane on which the semiconductor layer is formed. The configuration of the cross section shown in FIG. 32A is the same as that in FIG. In the plan view of FIG. 32B, the region indicated by “P” is the P-type electrode 733a, and the region surrounding the P-type electrode with a gap is the N-type electrode 733b. In the drawing, a broken line 1331 indicates a boundary between the semiconductor layers (433a to 433c) and the reflective conductor film 533. As described above, each of the optical microcells 133 has an independent structure and is electrically isolated from each other by mutually insulating the P-type layers.
The semiconductor layers and electrodes of each optical microcell shown in the plan view of FIG. 32 (b) may be formed so as to have rounded corners as shown in FIG. In particular, by using a light-emitting layer (semiconductor layer) with rounded corners as indicated by broken lines 4334, electric field concentration that occurs when the four corners of the light-emitting layer are formed at right angles can be prevented. With the rounded shape, it is possible to minimize the flow of current without contributing to light emission due to electric field concentration.

FIG. 34 shows an example in which an optical micromodule (see FIG. 28) configured by arranging the above optical microcells is formed on a wafer. The _SA surface shown in FIG. 34 corresponds to the _SA surface (FIG. 28) of the optical micromodule 232. In this example, an optical micromodule 232 of about 1 mm square is formed on a 3-inch wafer 271, and each optical micromodule 232 has optical microcells 1321 formed at a pitch of about 100 μm. 64 (8x8) are built. The optical microcell may be formed using any method shown in FIGS.
Further, as shown in FIG. 34, a power wiring layer 772 can be formed on the optical microcell, and a flip-chip structure electrode 802 for supplying power to each microcell can be formed. The flip-chip structure electrode can be formed, for example, by performing copper plating or solder plating in a wafer state. Further, the method is not limited to the method of forming in a wafer state, and each optical micromodule can be formed into a chip state and then formed by a method called a stud bump. Since these methods are not related to the essential part of the present invention, the description thereof will be omitted.
In order to cut out each optical micromodule from the wafer into a chip state, an optical microcell adjacent to an 8 × 8 optical microcell constituting one optical micromodule can be used as a scribe line. Each optical microcell is electrically and optically independent until the power supply wiring layer is formed, so that it can be used as a scribe line without being used as a light emitting portion. The optical micromodule is not limited to an 8 × 8 cell configuration, and the number of cells can be freely selected by changing the pattern after the power wiring layer.

Some examples of the micromirror different from the above-described forming method will be described.
The optical microcell shown in FIG. 35 is made of a transparent electrode 7341, an N-type GaAlN layer 434b, an active layer 434c, a P-type GaAlN layer 434a, a reflective conductor film 534, a silicon oxide film 574, and Al on a sapphire substrate 334. A P-type electrode 734a and an N-type electrode 734b are formed. The N-type electrode 734b also serves as a micromirror 634. As described above, the silicon oxide film 574 can contain high-concentration phosphorus in order to form the tilt of the micromirror using the silicon oxide film.
In the portion near the bottom of the recess formed in the silicon oxide film 574, that is, in the portion close to the transparent electrode 7341, the slope becomes gentle, so that the light emitting active layer 434c is formed at a position higher than the bottom of the recess. desirable. In the example of this figure, the thickness of the N-type GaAlN layer 434b is made thicker than the other layers, and the active layer 434c is devised so as to be formed at a position higher than the bottom of the concave portion of the silicon oxide film 574.

  The micromirror part of the optical microcell shown in FIG. 36 has a barrier transparent insulation for separating a silicon oxide film containing high-concentration phosphorus and the light-emitting layer when the light-emitting layer (semiconductor layer) dislikes high-concentration phosphorus. An example in which a film 5742 is provided is shown. The barrier transparent insulating film becomes a phosphorous barrier against a light emitting layer that dislikes phosphorous. The thickness of this layer can be made thin so that the shape of the slope of the recess of the silicon oxide film is not affected. The inclination angle is determined by the silicon oxide film 5741 containing high-concentration phosphorus as in the case of FIG.

  In the case shown in FIG. 35, the slope of the silicon oxide film near the bottom of the recess becomes gentle, so that the active layer for light emission is formed at a position higher than the bottom of the recess. In the example shown in FIG. 37, in addition, in order to capture the light that leaks from the active layer to the N-type GaAlN layer and is emitted from the side surface by the micromirror, the inclination angle is approximately 45 ° to the bottom of the recess of the silicon oxide film 5744. It is processed to make. For example, instead of using dry etching to form the Al contact hole for the N-type electrode provided in the silicon oxide film 5744, a wet etching technique that causes under-etching is used to incline (taper) the contact portion at the bottom of the recess. ) Is formed. As a result, a tapered silicon oxide film 5744 inclined to the bottom of the recess can be formed. In general, there are few cases of intentionally underetching the wet etching technique that causes underetching, but under-etching is a known phenomenon if the adhesion between the photoresist and the target film to be etched is lowered.

  FIG. 38 is a diagram showing the optical microcell manufactured by the above method with the light collecting direction z facing upward, and shows the direction in which the light emitted from the active layer 435c travels. An optical microcell including a light emitting layer including an N-type GaAlN layer 435b, an active layer 435c and a P-type GaAlN layer 435a, a reflective conductor film 535, a silicon oxide film 575, a P-type electrode 735a and an N-type electrode 735b made of Al as a material. Among the light emitted from the active layer 435c, the light emitted in the light collecting direction z passes through the sapphire substrate 335 as it is and proceeds straight in the light collecting direction (p). The light emitted in the direction opposite to the light collecting direction z is reflected by the reflective conductor film 535 on the back surface, passes through the sapphire substrate 335, and gathers in the light collecting direction (q). Light in a direction substantially perpendicular to the light collecting direction z, that is, light emitted along the active layer and light emitted from the side surface through the N-type GaAlN layer 435b are reflected by the micromirror. And gather in a substantially condensing direction (r, r ′).

The micromirror is formed in a substantially trapezoidal shape so that the shape of the light emitting layer is narrow toward the opposite side widely on the substrate side, and includes a transmission film layer formed so as to cover at least the side surface of the light emitting layer, It can also be configured by providing a reflection film on the outer surface of the transmission film layer. The substantially trapezoidal shape refers to a shape in which a cross section perpendicular to the substrate of the light emitting layer is a substantially trapezoid with a long base in contact with the substrate. That is, the side surface of the light emitting layer itself is formed to be inclined at an angle within the predetermined range.
The manufacturing example of the micromirror shown in FIG. 39 shows a structure in which the reflective conductor layer (534 in FIG. 35) is not provided and the light emitting layer (semiconductor layer) itself is tapered. FIG. 39 shows a state in which the side surface of the GaAlN semiconductor layer constituting the light emitting layer is taper-etched using a wet etching method that causes under-etching when etching GaAlN that is the light emitting layer. In this case, instead of the reflective conductor film (514), for example, a P-type electrode and an N-type electrode made of Al can be used as the back reflection film, and light is reflected by these electrode layers.
In FIG. 39A, the GaAlN semiconductor layers (434a to 434c) constituting the light emitting layer are etched by using a wet etching method that causes under-etching to form the above structure, and the side surfaces are inclined. Shows the state. That is, the wet etching is performed with a low degree of adhesion between the photoresist 1721 and the P-type GaAlN film 434a. In this structure, the silicon oxide film does not need to contain high-concentration phosphorus, and this structure is suitable for a semiconductor that dislikes a phosphorus-containing oxide film.

Furthermore, in order to realize a micromirror by forming a slope on the side surface of the light emitting layer as shown in FIG.
40A, a transparent electrode layer 7361 made of indium oxide or the like is formed on a sapphire substrate 336, and a light emitting layer including an N-type GaAlN layer 436b, an active layer 436c, and a P-type GaAlN layer 436a is stacked. It represents the state. A pattern of a photoresist 1731 for etching the light emitting layer is formed on the upper surface.
In FIG. 40B, the transparent electrode layer 7361 is left on the substrate, and the light emitting layer is removed using a wet etching technique with a width of 20 μm and a pitch of 100 μm, for example, and a slope is formed on the side surface of the light emitting layer. State. This can be formed using photolithography and etching steps by reducing the adhesion between the photoresist 1731 and the GaAlN layer. In this example, the transparent electrode layer 7361 made of indium oxide plays a role of etching end point management. After this etching is completed, the photoresist is peeled off.
In FIG. 40C, following the above process, a reflective conductor film using nickel, chromium, silver, or the like is formed on the entire surface, a photoresist is applied, and the reflective conductor is formed in the same pattern as in FIG. A state where a reflective conductor film 536 made of nickel, chromium, silver, or the like is formed on the light emitting layer by etching the film is shown.

FIG. 40D shows a state in which, after the above process, a silicon oxide film 576 is formed on the substrate, a photoresist 1732 is applied, and a pattern for forming an electrode contact portion is formed.
FIG. 40E shows a state in which the electrode extraction opening is taper-etched in the silicon oxide film 576 following the above-described process. Similar to FIG. 40B, it can be formed by intentionally reducing the adhesion between the photoresist 1733 and the silicon oxide film and performing wet etching. As a result, the lateral etching in the drawing is promoted, the bottom of the recess of the silicon oxide film is etched into a rounded shape, and the shape of the silicon oxide film in the vicinity of the contact portion 5761 becomes a gentle shape. After the etching is completed, the photoresist is peeled off.
FIG. 40G shows a state in which the P-type electrode 736a and the N-type electrode 736b are formed using Al or the like as a material following the above process. Since the portion of the N-type electrode 736b constitutes a micromirror, the material of these electrodes is preferably a laminated structure containing not only Al but also chromium, nickel, silver or the like. For example, a structure in which a thin chrome, nickel or silver layer is provided for the role of a mirror and an Al layer is provided thereon as an electrode material can be cited.

The indium oxide (transparent conductive film 7361) portion in the above case may be replaced with a high concentration N-type GaAlN layer (N ⁺ GaAlN layer). If high-concentration N-type GaAlN is used, it is easy to form such a thin film layer on the sapphire substrate. This is a method of creating a substrate by a simpler method than a method of forming a semiconductor layer and indium oxide on the sapphire substrate described in the section of FIG. is there. However, in the case of using an indium oxide film, as shown in FIG. 40B, the end point of etching of the semiconductor layer could be managed by the indium oxide film. On the other hand, when a high concentration N-type GaAlN layer is used, although there is a slight difference in etching rate due to the difference in the impurity concentration of the semiconductor, it is difficult to perform complete etching end point management. Therefore, it is necessary to realize the shape shown in FIG. 40B by managing the etching rate and time.

FIG. 41 is a diagram showing the above-described optical microcell configured using a high-concentration N-type GaAlN (N ⁺ GaAlN layer) 436d with the condensing direction upward, and the direction in which the light emitted from the active layer travels. Represents. An optical micro including an N ⁺ GaAlN layer 436d, an N—GaAlN layer 436b, an active layer 436c, a P—GaAlN layer 436a, a reflective conductor film 536, a silicon oxide film 576, a P-type electrode 736a and an N-type electrode 736b made of Al. In the cell, among the light emitted from the active layer, the light emitted in the direction of the light collecting direction z passes straight through the sapphire substrate 336 in the light collecting direction (p). The light emitted in the direction opposite to the condensing direction z is reflected by the reflective conductor film 536 and gathers in the condensing direction through the sapphire substrate 336 (q). Further, light in a direction perpendicular to the light collecting direction z, that is, light emitted along the active layer is reflected by the micromirror (N-type electrode 736b) and gathers in a substantially light collecting direction (r, r ′). ).

(Embodiment 3)
In the optical microcell and the optical micromodule of the present invention, the substrate may be composed of a transparent substrate that transmits light emitted from the light emitting layer and a second substrate. The light emitting layer is formed on the surface of the transparent substrate opposite to the light condensing direction, and a side reflecting portion (micromirror) is formed on the second substrate. An optical microcell and an optical micromodule can be configured by attaching the transparent substrate on which the light emitting layer is formed and the second substrate on which the micromirror is formed to face each other. In this case, a micromirror is formed on the second substrate so as to be in the vicinity of the side surface of the light emitting layer in accordance with the position and size of the light emitting layer formed on the transparent substrate. The micromirror can be formed by tilting at an angle within the predetermined range using silicon as a base material.

  The inclination angle (α) of the micromirror is, for example, 54 ° by using silicon having a (110) plane orientation as the second substrate and etching the silicon with an alkaline aqueous solution such as potassium hydroxide. Can be formed at an angle. The above angle can be easily formed with good reproducibility by utilizing the selective etching property of the plane orientation of silicon. In this way, a micromirror is formed on a silicon wafer, a light emitting layer is formed on a sapphire wafer having the same diameter, and the silicon wafer and the sapphire wafer are bonded together so that the side surface of the light emitting layer is surrounded by the micromirror. Thus, an optical microcell and an optical micromodule with a built-in micromirror can be realized.

FIG. 42 is a cross-sectional view showing an example in which the optical micromodule is mounted on a package. The light collecting direction z is above the package in the figure. In FIG. 42, an optical micromodule 251 is mounted in a package including a protective transparent cap 973 and a package substrate 951. The optical micromodule 251 includes, for example, an active layer 451c sandwiched between an N-type semiconductor layer and a P-type semiconductor layer on the lower surface of the sapphire substrate 351 (the surface opposite to the condensing direction z), and below that A back reflection film 551 is provided. A micromirror 651 is formed on the silicon substrate 361, and the optical micromodule 251 is configured by bonding the substrate 351 on which a semiconductor layer or the like is formed to the silicon substrate 361. The micromirror 651 is inclined at an angle within the predetermined range, and is disposed in the vicinity of the side surface of the active layer 451c.
The micromirror 651 can be formed so as to surround the side surface of the active layer 451c. As described above, one unit including a light-emitting layer that is a semiconductor layer including an active layer and a micromirror that surrounds the side is called an optical microcell. In the cross section of the optical micromodule 251 shown in FIG. 42, the cross sections of two optical microcells are visible.
Of the light emitted from the active layer 451 c included in the optical micromodule 251, the light emitted toward the transparent substrate 351 side, that is, in the light collecting direction z, is emitted through the transparent substrate 351 in the light collecting direction. Light emitted from the active layer to the side opposite to the transparent substrate 351 is reflected by the back reflecting film 551 and is emitted through the transparent substrate 351 in the light collecting direction. Light emitted from the active layer in the side surface direction (a direction perpendicular to the light collecting direction z) is reflected by the micromirror 651 and is emitted in a substantially light collecting direction through the transparent substrate 351. The relationship between the inclination angle α of the micromirror with respect to the active layer and the light reflection direction is as described above (see FIG. 5).

  The optical micromodule can include an electrode for supplying power to each light emitting layer, power supply wiring, and the like. In FIG. 42, the electrodes of the optical micromodule 251 are installed on the side opposite to the light collecting direction z and wired in the power supply wiring layer 781. The power source is concentrated on the flip chip electrode 821 and is electrically connected to the lead 861 through this. The lead 861 is pulled out of the package and used for external connection.

  FIG. 43 shows a case where a phosphor 921 containing a phosphor is provided in the light collecting direction from the optical micromodule 251. As in FIG. 42, the optical micromodule 251 is mounted on the package substrate 952 via the flip chip electrode 821. A cap 974 having an inclined reflection portion on the inner surface is filled with a phosphor 921, and the whole is further sealed with a transparent cap 984. Similarly to the above, the light emitted from the active layer included in the optical micromodule 251 is collected in the light collecting direction z, and excites the fluorescent substance contained in the phosphor 921. Most of the light emitted by the fluorescent material is directly emitted in the light collecting direction, and the light scattered in the package is reflected by the inclined side surface in the cap 974 and collected in the light collecting direction.

Next, an example of an optical micromodule configured by arranging optical microcells similar to the above in a matrix will be described.
44 and 45 are a side view and a perspective view of the optical micromodule 252. FIG. In both figures, the light collecting direction z is shown downward. The optical micromodule 252 includes an optical microcell layer 152 including a light emitting layer and a micromirror on the upper surface of one sapphire substrate 352. The optical microcell layer 152 is formed with a large number of optical microcells 1521 each having a light emitting layer, and micromirrors 652 are provided at both ends of each optical microcell 1521. One optical microcell 1521 can be formed so that the four directions on the side surface of the light emitting layer are surrounded by the micromirror 652. A back reflection film 552 is provided on the upper surface of the optical microcell layer 152.

  Further, a power wiring layer 782 and a flip chip layer 822 for supplying power to each optical microcell are provided on the back reflecting film 552. Electrodes for supplying power to the light emitting layer of each optical microcell are wired in the power supply wiring layer 782 and are collectively electrically connected to the flip chip electrode 822. The power supply wiring layer 782 and the flip chip electrode 822 are provided on the side opposite to the light collecting direction z so as not to interfere with light collecting.

As shown in FIG. 44, the optical micromodule 252 is provided with nine micromirrors 652 on one side, and constitutes eight optical microcells 1521 sandwiched between the micromirrors 652. In Figure 45, are represented the S _A surface S _B 8 pieces each surface of the optical micro-cell, the optical micromodule 252 will be composed of 8 × 8 = 64 pieces of light microcells . As described above, power to the 64 optical microcells is supplied from the flip chip electrode 822 via the power supply wiring layer 782.

FIG. 46 is a side view showing the optical micromodule 252 with the light collecting direction z facing upward. Of the light emitted from the active layer in the optical microcell 1521, the light directed in the light collecting direction z travels straight in the light collecting direction through the transparent substrate 352 (p). The light emitted in the direction opposite to the light collecting direction z is reflected by the back reflecting film 552 and collected in the light collecting direction through the transparent substrate 352 (q). Further, light in a direction perpendicular to the condensing direction z is substantially condensed by the micromirror 652 formed in four directions and inclined at an angle of about 45 ° (for example, 30 ° to 60 °) with respect to the active layer. The light is reflected in the direction and collected in the light collecting direction through the transparent substrate 352 (r). As described above, when the angle (α) of the micromirror with respect to the active layer is 54 °, the direction of the reflected light r is 18 ° with respect to the light collection direction z as shown in the figure.
The light perpendicular to the light collecting direction z propagates along the thin film of the light emitting layer. In order to avoid attenuation during propagation, it is preferable that the size of the light emitting layer is as small as possible, the area occupied by the micromirror in the optical microcell is as small as possible, and the distance between the light emitting layer and the micromirror is as short as possible. When the optical microcells are arranged, the size of each optical microcell, that is, the pitch of the micromirrors can be formed with a width and a depth of about 100 μm, for example.

FIG. 47 is a cross-sectional view (a) and a plan view (b) showing the structure of one optical microcell in more detail. The plan view of FIG. 47 (b) shows a semiconductor layer and a micromirror portion together with a view seen from the electrode surface in order to explain the structure of the optical microcell and its electrode.
The optical microcell 153 shown in FIG. 47A includes a sapphire substrate 353, a transparent electrode 7531 such as ITO, an N-type semiconductor layer 453b, an active layer 453c, a P-type semiconductor layer 453a, a Ni thin film 5531 on the sapphire substrate side, and a silicon substrate. A Ni thin film 5532, a silicon layer 363, and a PIQ film (insulating polyimide film) 583 are provided.
With this structure, among the light emitted from the active layer, the light directed in the light collecting direction z travels through the sapphire substrate 353 in the light collecting direction. The light emitted in the direction opposite to the condensing direction z is totally reflected by the thin film 5531 which is a back reflecting film and travels through the sapphire substrate 353 in the condensing direction. Light in a direction perpendicular to the light collecting direction z, that is, light along the active layer is reflected in a substantially light collecting direction by the micromirror 653 formed so as to surround the four directions on the side surface, and passes through the sapphire substrate 353. Proceed substantially in the direction of light collection.
As shown in FIG. 47 (b), the regions of the P-type electrode 753a and N-type electrode 753b made of Al or the like, and the region where the semiconductor layers (453a to 453c) and the like are stacked have four corners at right angles. Instead, it is rounded. Thereby, average light emission can be promoted while avoiding concentration of the electric field.

A method of manufacturing the optical microcell (optical micromodule) having the above structure in a wafer state will be described with reference to FIGS.
The substrate shown in FIG. 48A is obtained by epitaxially growing a high-concentration P-type silicon layer 3632 with a thickness of about 3 μm using an N-type silicon 363 with a (110) plane orientation as a substrate, and further with an N-type silicon with a thickness of about 5 μm. This is a substrate on which a layer 3633 is epitaxially grown. An oxide film 584 having a thickness of about 0.5 μm is formed on this substrate, and a pattern is formed by photolithography.
FIG. 49A is a perspective view of the N-type silicon wafer, in which an oxide film (SiO ₂ ) 584 having a width of about 2 μm is left by photolithography like a grid, and the pitch is about 100 μm. ing.
The N-type silicon layer 3633 is etched by placing the substrate in an alkaline (eg, potassium hydroxide) etchant. In FIG. 48 (b), the etching of the N-type silicon layer 3633 stopped at the (111) plane due to the anisotropic etching characteristic that the etching rate of the (111) plane orientation of silicon was slow, and it stood at 54 °. A state where a slope is formed is shown. FIG. 49B is an enlarged view of this. The inclined surface of the N-type silicon layer 3633 is formed in all four directions.
FIG. 48C shows a state in which the Ni thin film 5532 is formed on the wafer from which the oxide film 584 has been removed. The silicon mirror surface can be used in this state as it is, or it can be used to facilitate covalent bonding when an oxide film is formed and merged with a later sapphire substrate. The Ni thin film is formed to facilitate covalent bonding with the Ni thin film formed on the sapphire substrate side. In this example, a Ni thin film is used, but it is also possible to use a silver thin film having a high light reflectance. Bonding is facilitated by using a silver thin film for the substrate instead of the Ni thin film.
A silicon wafer having a micromirror formed in this shape is completed.

Next, an example of a manufacturing method on the transparent substrate (sapphire substrate) side will be described.
The substrate shown in FIG. 50A is a 3-inch sapphire substrate 353, a transparent electrode layer 7531 such as ITO, an N-type GaAlN layer 453b, an active layer 453c, a P-type GaAlN layer 453a, a total reflection conductor (Ni thin film) 5531. Are stacked. As a whole, the film is as thin as several μm.
FIG. 50B shows a state in which a groove 3531 having a depth of 10 μm and a width of 20 μm is formed on the substrate. This groove can be formed by photolithography and etching processes.
FIG. 50C is a diagram showing a state immediately before the silicon substrate on which the micromirror is formed (the state in FIG. 48C) is bonded to the sapphire substrate 353 in which the groove is formed. The two wafers are bonded to each other so that the apex of the micromirror formed on the silicon wafer is positioned at the center of the groove on the sapphire substrate.
FIG. 50D shows a state where both wafers are combined. The surface layers of the two wafers are mirror surfaces, and in this case, both are Ni thin film layers (5531, 5532), and thus are completely integrated at the molecular level by intermolecular attractive force. As a result, the micromirror part is completely isolated from the outside, and a stable mirror can be formed. This technique is similar to the silicon bonding technique that has recently become popular. In the case of silicon bonding, the silicon surface and the silicon oxide surface are bonded together. In this case, the Ni thin film on the silicon wafer and the Ni thin film on the sapphire substrate are bonded together.

The above is an example in which a silicon substrate and a sapphire substrate are bonded together via a Ni thin film. However, when the wafer diameter is increased, physical property values such as a difference in Young's modulus and a coefficient of thermal expansion of both wafers are obtained. Due to the difference, an organic adhesive layer may be required for bonding. Since the process after the bonding does not require a temperature treatment of several hundred degrees that exceeds the limit temperature of the organic material, the silicon substrate and the sapphire substrate can be bonded to each other through the organic material. In that case, an adhesive layer can be formed on the upper surface in the state of FIG. 50A and etched together with other thin film layers. However, it is necessary to make the procedure so that the adhesive does not enter the groove portion shown in FIG.
FIG. 50E shows a state in which the silicon substrate side of the bonded wafer is etched, leaving only a thickness of about 3 μm. In the figure, 3362 is a silicon layer. By utilizing the low etching rate of the high-concentration P-type silicon layer 3362, an accurate thickness can be left. The silicon layer having a thickness of about 3 μm is a part that supports the micromirror as a structure.

A process of forming the electrode of the optical microcell from the state where the silicon substrate and the sapphire substrate are bonded together as described above will be described with reference to FIG.
FIG. 51A shows a state in which a pattern of a photoresist 181 is formed on the substrate shown in FIG. In this state, etching of the silicon layer 3632, etching of the silicon side reflection conductor (Ni thin film in this case) 5532, etching of the sapphire side reflection film (Ni thin film in this case) 5531, etching of the semiconductor layers 453a to 453c, Etching is completed using the transparent electrode layer (ITO in this case) 7531 as a stopper.
FIG. 51B shows a state after the etching. Since the silicon layer 3632 has a (110) plane orientation, the etched wall surface is tapered with an inclination of 54 °. Etching leaving behind.
FIG. 51 (c) is a diagram showing a state where PIQ (insulating polyimide film) 583 is applied and PIQs of the P-type electrode portion and the N-type electrode portion are removed.
FIG. 51D shows a state in which a P-type electrode 753a and an N-type electrode 753b are formed by evaporating and then etching an electrode material made of Al or the like from the above state.
Through the above steps, the micromirror, the light emitting layer, and the electrode layer of the optical microcell were formed. In this example, the structure using the PIQ that can be used at a low temperature has been described. However, a low-temperature stacked silicon oxide film can be used instead of the PIQ film. In that case, attenuation of light in the film can be reduced as compared with using PIQ.

FIG. 52 shows how light is reflected in the optical microcell formed as shown in FIG. The micromirror is a Ni film 5532 on the surface of the convex portion formed on the silicon substrate. In FIG. 52, the light emitted in the horizontal direction, that is, along the thin film in the active layer 453c is reflected by the micromirrors formed in the four directions and travels in the substantially condensing direction (r). In this example, since the inclination angle of the micro mirror is 54 °, the light is reflected by the micro mirror in a direction inclined by 18 ° with respect to the light collection direction z. Further, the light emitted from the active layer in the direction opposite to the micromirror, that is, in the direction of the N-type electrode 753b is reflected by the PIQ film or reflected by the negative electrode Al, and returns to the light emitting layer. Head to. A part of the light is internally reflected (r ′) in the light collecting direction by the inclination of the negative electrode Al thin film. If a silicon oxide film is used instead of the PIQ film, it is almost reflected (r ′) by the negative electrode Al thin film.
As described above, in view of the relationship between the tilt angle (α) of the micromirror and the light collection, α = 45 ° is preferable. The micromirror formed using a predetermined plane orientation of silicon is α = 54 °, and the direction of light reflected by the micromirror can be inclined by 18 ° with respect to the light collection direction z. A highly preferred micromirror can be realized.

In FIG. 53, the optical microcells shown in FIG. 51 (d) are arranged on a wafer, a power wiring layer 782 for connecting the P-type electrode and the N-type electrode of each optical microcell 1521 is provided, and a flip-chip electrode is further provided. 3 represents an optical micromodule having a layer 822 formed thereon. In the figure, an electrode is formed on an 8 × 8 optical microcell. The flip chip electrode may be formed in a columnar shape or the like in the wafer state as described above, or simply provided with a planar electrode (flip chip electrode) for flip chip mounting and divided into each optical micromodule and then stud bumps. It may be formed by such a method. In addition, a flip chip electrode may be provided on the optical micromodule, and the optical micromodule may be bonded to a protruding electrode provided on the side of the package substrate or the like.
From this wafer state, the optical micromodule shown in FIG. 46 can be cut out. As a scribe line for cutting out an optical micromodule, an optical microcell adjacent to an 8 × 8 optical microcell can be used. Each optical microcell is electrically and optically independent until the power supply wiring layer is formed, and thus can be used as a scribe line without being used as a light emitting portion. In this example, the number of cells is 8 × 8, but the number of cells can be freely selected by changing the pattern after the power wiring layer.

  The present invention is not limited to the examples detailed in the first, second and third embodiments. The basic element of the present invention is to extract as much light as possible from the light emitting layer and the light reflected from the semiconductor layer in the light collecting direction. Therefore, it is important to configure the reflecting portion with a material having as high a reflectance as possible and to minimize the absorption and attenuation of light in the optical microcell. For this purpose, for example, in the case of an optical microcell (see FIG. 25) or an optical micromodule having a structure in which a light emitting layer is formed on a transparent substrate (sapphire substrate) and light from the light emitting layer is collected through the transparent substrate. Further, after mounting the flip chip electrode or the like, the transparent substrate layer can be removed.

For example, as shown in FIG. 54, after the flip chip electrode is mounted, that is, after the light emitting layer and the power supply wiring layer are physically fixed, the sapphire layer that has finished serving as the substrate is removed by a lift-off method. It is possible. Thereby, attenuation of the light in a sapphire layer can be eliminated. Furthermore, the removal of the sapphire layer exposes the surface on the light-collecting direction side of the light-emitting element (the surface on the light-emitting layer side that was in contact with the sapphire substrate). The total reflection in the layer can be reduced, and as a result, the light collection efficiency can be increased.
FIG. 55B is a cross-sectional view showing a state in which the optical micromodules 238 are arranged and formed on the wafer 273 (transparent substrate 338) shown in FIG. In the optical micromodule 238, optical microcells 1381 having micromirrors 638 are formed in an array, and after the power supply wiring layer 783 is formed, the flip chip electrode 803 is formed. In another wafer 943, a through conductive via 9431 and a surface electrode 9432 are formed. The electrode of the optical micromodule 238 is connected to the surface electrode 9432 on another wafer 943 through the flip chip electrode 803. In such a state, since the structure on the substrate (light emitting layer, micromirror, power supply wiring layer, etc.) constituting the optical micromodule 238 is physically fixed, the transparent substrate 338 can be removed. . The transparent substrate 338 may be removed after being separated into individual optical micromodules. FIG. 55C is a diagram showing the optical micromodule 239 from which the optical micromodules 238 on the wafer 273 are individually separated and the transparent substrate 338 is removed, upside down.

The above is an example, and the selection and combination of materials for the optical microcell are important factors. In the examples, nickel, cobalt, and the like have been described as examples of the reflective film, but it is also possible to use a material having higher reflectivity such as silver.
Moreover, although GaAlN was mentioned and demonstrated as a semiconductor material, it is applicable also to GaN and other semiconductor materials.
Furthermore, the structure of the present optical microcell or the present optical micromodule is not limited to a light emitting diode using a phosphor, but can be commonly used for a light emitting diode that emits visible light.
In addition, the present invention is not limited to the embodiments described in detail above, and various modifications or changes can be made within the scope of the claims of the present invention.

  Applications of light emitting diodes are expanding for energy saving. In the automobile field, it is used in a wide range of fields such as lamps including headlights, lamps using LEDs for home use, backlights for liquid crystal TV receivers, and traffic lights for industrial use. Increasing the efficiency of light-emitting diodes is a technology that will become even more important in the future. The present invention is not limited to white light-emitting diodes, but has a basic configuration that can be applied to existing single-color light-emitting diodes, and is a common technique in the age of energy saving.

100, C _{1 to} C ₂₂ , 102, 103, 104, 1321, 133, 1381, 1521, 153; optical microcells (light emitting diode elements), 1611 to 1614, 1621 to 1624, 1631 to 1634, 1711, 1721, 1731 , 1732, 181; Photoresist, 201, 231, 232, 237, 238, 239, 251, 252; Optical micromodule (light emitting diode module), 271, 273; Wafer, 302, 303, 304, 331, 332, 333 334, 335, 336, 338, 351, 352, 353; substrate, 361, 362; second substrate (silicon substrate), 363; N-type silicon layer, 3632; high-density P-type silicon layer, 3633; N-type Silicon layer, 402, 403, 404, 431; Optical layer (semiconductor layer), 40a, 401a, 402a, 403a, 404a, 431a, 433a, 434a, 435a, 436a, 453a; P-type semiconductor layer (P-type region), 402c, 431c, 433c, 434c, 435c, 434c 436c, 451c, 453c; active layer, 40b, 401b, 402b, 403b, 404b, 431b, 433b, 434b, 435b, 436b, 453b; N-type semiconductor layer (N-type region), 436d; high-density N-type semiconductor layer , 50, 502, 503, 504, 531, 532, 533, 534, 536, 551, 552, 5531, 5532; back reflective film, 562, 563, 564, 573, 574, 5741, 5744, 576; insulating film ( SiO ₂ film), 583; insulating film (PIQ film), 584; SiO Film, 61,602,603,604,631,632,634,638,651,652,653; micromirrors (lateral reflection part), 701a, 702a, 703a, 704a, 733a, 734a, 735a, 736a, 753a P (P type) electrode, 701b, 702b, 703b, 704b, 733b, 734b, 735b, 736b, 753b; N (N type) electrode, 733, 7331, 7341, 7351, 7361, 7531; Transparent conductive film, 7613 7614; transparent conductive film, 761a, 761b, 771, 772, 781, 782, 783; power wiring layer, 81a, 81b, 801, 802, 803, 821, 822; flip-chip electrode, 85, 851, 852, 861 , 862; lead, 90, 901, 921; phosphor, 941, 942, 943, 951, 952; package substrate, 97, 971, 972, 973, 974; cap, 98, 983, 984; cover glass, p, q, r, r ′; light traveling direction, S: light emitting layer A direction parallel to the (active layer), z: light collecting direction, α: inclination angle of the micromirror.

Claims (19)

A light-emitting diode element comprising a light-emitting layer formed in a certain region on a substrate by a thin film, and extracting light emitted from the light-emitting layer in a light collecting direction perpendicular to the light-emitting layer,
In the vicinity of the side surface of the light emitting layer, a side reflecting portion inclined at an angle of a predetermined range with respect to the light emitting layer,
The light emitting diode element, wherein light emitted from the light emitting layer in a direction substantially parallel to the light emitting layer is reflected in the light collecting direction by the side reflecting portion. The side reflecting portion is formed so as to surround all or part of the side surface of the light emitting layer,
The light emitting diode element according to claim 1, wherein the angle in the predetermined range is not less than 0 degrees and not more than 90 degrees. Further comprising a back reflection film on the opposite side of the light collection direction across the light emitting layer,
The light emitting diode element according to claim 1, wherein light emitted from the light emitting layer to the side opposite to the light collecting direction is reflected by the back reflecting film in the light collecting direction.   The light emitting diode element according to claim 1, wherein the light emitting layer and the side reflecting portion are formed on a surface of the substrate on the light collecting direction side. The substrate is a transparent substrate that transmits light emitted from the light emitting layer;
The light emitting diode element according to claim 4, wherein the back reflection film is formed on a surface of the transparent substrate opposite to the light collecting direction. A wall surface formed on the substrate so as to surround the side surface of the light emitting layer and facing the side surface of the light emitting layer is provided with a side wall portion inclined at an angle of the predetermined range,
The light emitting diode element according to claim 4 or 5, wherein at least a reflective film formed on the wall surface facing the side surface of the light emitting layer constitutes the side reflecting portion. The substrate is a transparent substrate that transmits light emitted from the light emitting layer,
The light emitting diode element according to any one of claims 1 to 3, wherein the light emitting layer is formed on a surface of the transparent substrate opposite to the light collecting direction. A transmissive membrane layer formed so as to transmit light emitted from the light emitting layer so as to cover at least a side surface of the light emitting layer and to have a thickness that is thick on the substrate side and thin toward the opposite side; ,
The light emitting diode element according to claim 7, wherein a reflection film formed on an outer surface of the transmission film layer constitutes the side reflection portion. The light emitting layer is formed in a substantially trapezoidal shape that is wide on the substrate side and narrows toward the opposite side, and transmits a light emitted from the light emitting layer so as to cover at least the side surface of the light emitting layer. With layers,
The light emitting diode element according to claim 7, wherein a reflection film formed on an outer surface of the transmission film layer constitutes the side reflection portion. The substrate comprises a transparent substrate that transmits light emitted from the light emitting layer, and a second substrate,
The light emitting layer formed on the surface of the transparent substrate opposite to the light condensing direction;
The side reflection part formed on the second substrate so as to correspond to the light emitting layer;
With
4. The light-emitting diode element according to claim 1, wherein the transparent substrate on which the light-emitting layer is formed and the second substrate on which the side reflection portion is formed are attached to face each other. . In order from the transparent substrate side, a first conductive layer that transmits light emitted from the light-emitting layer and has conductivity, the light-emitting layer, a second conductive layer that has conductivity, a power wiring layer, With
Furthermore, it comprises at least two flip chip electrodes or flip chip electrodes disposed on the power wiring layer,
In the power supply wiring layer, a first conductor electrically connected to the first conductive layer and a second conductor electrically connected to the second conductive layer are respectively wired.
11. The light-emitting diode element according to claim 7, wherein each flip chip electrode or flip chip electrode is electrically connected to the first conductor and the second conductor, respectively.   The light emitting diode device according to claim 11, wherein the transparent substrate is removed after the flip chip electrode or the flip chip electrode is disposed on the power wiring layer.   The light-emitting diode device according to claim 12, wherein the exposed surface on the light-emitting layer side that is in contact with the removed transparent substrate is processed into a ground surface. A light emitter containing a fluorescent material is further disposed on the light collecting direction side from the light emitting layer,
The light emitting diode element according to claim 1, wherein the fluorescent material absorbs at least a part of light emitted from the light emitting layer and emits light having different wavelengths.   11. A light emitting diode module comprising a plurality of the light emitting diode elements according to claim 1 formed on a single substrate, wherein the light emitting diode elements are electrically connected. A plurality of light emitting diode elements according to any one of claims 7 to 10 are formed on a single substrate,
Each of the light emitting diode elements, in order from the transparent substrate side, transmits light emitted from the light emitting layer and has conductivity, the light emitting layer, and the second conductive material having conductivity. A layer, and
Furthermore, on the plurality of light emitting diode elements, a power wiring layer, and at least two flip chip electrodes or flip chip electrodes disposed on the power wiring layer,
In the power supply wiring layer, a first conductor electrically connected to the first conductive layer and a second conductor electrically connected to the second conductive layer are respectively wired.
Each of the flip chip electrodes or the flip chip electrodes is configured to be electrically connected to the first conductor and the second conductor, respectively.   17. The light emitting diode module according to claim 16, wherein the transparent substrate is removed after the flip chip electrode or the flip chip electrode is disposed on the power wiring layer.   18. The light emitting diode module according to claim 17, wherein the exposed surface on the light emitting layer side that has been in contact with the removed transparent substrate is processed into a background. A light emitter including a fluorescent material is further disposed on the light collecting direction side from the plurality of light emitting layers;
The light emitting diode module according to claim 15, wherein the fluorescent material absorbs at least a part of light emitted from each of the light emitting layers and emits light having a different wavelength.

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