KR101445451B1 - Light emitting diode and method for producing the same - Google Patents

Abstract

A light-emitting diode in which a protective film and an electrode film are formed with a uniform film thickness, stable light can be provided with high luminance, side deterioration is prevented, high reliability and long life can be achieved. The light emitting diode of the present invention is characterized in that the supporting structure portion 6 includes a part of the reflective layer 2 and the side surface 6b thereof is formed by wet etching and includes the inclined portion 6ba and the inclined portion 6ba The mesa structure 7 is formed such that the inclined side face 7a is formed by wet etching and the cross sectional area in the horizontal direction is directed toward the top face 7b And the protective film 8 covers the peripheral region 7ba of the top face 6a, the inclined portion 6ba, the inclined side face 7a and the top face 7b, The electrode layer 9 is in direct contact with the surface exposed from the power window 8b and is formed on the upper surface 6a of the semiconductor layer 5. [ Is a continuous film covering the protective film 8 and having a light emitting hole 9b.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode (LED)

The present invention relates to a light emitting diode and a method of manufacturing the same.

A light emitting diode having a point light source type in which light generated in the light emitting layer is taken out from a part of the upper surface of the device is known. In the light emitting diode of this type, it is known that the light emitting diode has a current constricting structure for limiting the energizing region in the light emitting layer to a portion within the plane (for example, Patent Document 1). In the light emitting diode having the current confinement structure, since the light emitting region is limited and light is emitted from the light emitting hole formed right above the region, a high light output is obtained and the emitted light is efficiently introduced into the optical component and the like It is possible.

In particular, among the point light circular light emitting diodes, a resonator-type light emitting diode (RCLED: Resonant-Cavity Light Emitting Diode) has a structure in which an abdomen of a standing wave generated in a resonator composed of two mirrors is positioned in a light emitting layer disposed in the resonator And operates in the LED mode without laser oscillation by setting the reflectance of the mirror on the light output side to be lower than the reflectance of the mirrors on the substrate side (Patent Documents 2 and 3). The resonator type light emitting diode is characterized in that it has a narrow emission line width, a high directivity of emitted light, and a short carrier lifetime due to spontaneous emission, due to the effect of the resonator structure, as compared with ordinary light emitting diodes Therefore, it is suitable for sensors and so on.

In the resonator type light emitting diode, in order to narrow the light emitting region in the direction parallel to the substrate, the upper mirror layer, the active layer, and the like are made to have a filler structure, and a layer having a light use opening is formed on the light extracting surface of the top surface of the filler structure (For example, Patent Document 4).

13 is a resonator type light emitting diode in which a lower mirror layer 32, an active layer 33, an upper mirror layer 34 and a contact layer 35 are sequentially arranged on a substrate 31, and the active layer 33 The upper mirror layer 34 and the contact layer 35 are formed as a filler structure 37 and the filler structure 37 and the periphery thereof are covered with a protective film 38, Type light emitting diode in which an opening 39a for light output is formed in the electrode film 39 on the top surface 37a (light extraction surface) of the filler structure 37. The resonator- Reference numeral 40 denotes a back electrode.

The current confinement structure of the pillar structure as shown in Fig. 13 can also be applied to a point light circular light emitting diode other than the resonator type.

Japanese Patent Application Laid-Open No. 2005-31842 Japanese Patent Laid-Open No. 2002-76433 Japanese Patent Application Laid-Open No. 2007-299949 Japanese Patent Application Laid-Open No. 9-283862

13, since the portions other than the filler structure after the formation of the active layer or the like are removed by dry etching of the anisotropy in forming the filler structure, the side surfaces 37b of the filler structure 37 Are formed vertically or steeply with respect to the substrate 31. In general, a protective film is formed on the side surface of the filler structure by a vapor deposition method or a sputtering method, and then a metal (for example, Au) film for electrodes is formed by a vapor deposition method. In this vertical or steep- There is a problem that it is difficult to form the film with a single thickness, and the film tends to be a discontinuous film. In the case where the protective film is a discontinuous film (indicated by symbol A in Fig. 13), the metal film for electrode is drawn into the discontinuous portion to contact with the active layer or the like, thereby causing leakage. Also, in the case where the metal film for the electrode is a discontinuous film (reference character B in Fig. 13), it is a cause of defective energization.

In addition, in the light emitting diode shown in Fig. 13, since the side surface 32a of the structure 32 supporting the filler structure is exposed, there is a problem that the side surface is in contact with moisture in air or air and deteriorates. Particularly, when the lower mirror layer 32 is a semiconductor layer having a high Al composition, the side surface is oxidized to deteriorate the characteristics.

Further, if dry etching is performed to remove portions other than the filler structure, an expensive apparatus is required, and etching time is also long.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a protective film and an electrode film formed thereon with a uniform film thickness so as to provide a stable and high-luminance light emission, And to provide a method of manufacturing a light emitting diode that can be manufactured at a lower cost than ever before, while reducing the defects of leakage and conduction, thereby improving the yield.

In order to achieve the above object, the present invention provides the following means.

(1) A light emitting diode including a compound semiconductor layer including a reflective layer and an active layer on a substrate, the light emitting diode comprising a support structure having an upper surface and a side surface, and a mesa structure having an inclined side surface and a top surface, Wherein the support structure includes at least a portion of the reflective layer and an inclined portion whose side is formed by wet etching and extends from the upper surface to the substrate side at least to a position exceeding the reflective layer, Wherein the mesa structure portion includes at least a portion of the active layer, the inclined side surface of the mesa structure portion is formed by wet etching, and the mesa structure portion Sectional area is continuously made smaller toward the top surface, Wherein at least a part of the support structure and the mesa structure are sequentially covered with a protective film and an electrode film, and the protective film includes at least a part of the upper surface, at least an inclined part of the side, And an energizing window which exposes a part of the surface of the compound semiconductor layer to the inside of the peripheral region when viewed from a plane, and the electrode layer comprises a compound window exposed from the energizing window Wherein the light emitting diode is a continuous film formed to directly contact the surface of the semiconductor layer and to cover at least a part of the protective film formed on the upper surface and to have a light emitting hole on the top surface of the mesa structure.

(2) The light emitting diode according to (1), wherein the reflective layer is a DBR reflective layer.

(3) The light emitting diode according to (2), further comprising an upper DBR reflecting layer on the side opposite to the substrate of the active layer.

(4) The tilting portion is composed of at least two inclined portions, the sectional area in the horizontal direction including each inclined portion is continuously small toward the top surface, and the cross sectional area in the horizontal direction including the inclined portion close to the top surface is smaller The light emitting diode according to any one of (1) to (3).

(5) The light emitting diode according to any one of (1) to (4), further comprising a light leakage preventing film on the electrode layer and / or the protective film.

(6) The light emitting diode according to any one of (1) to (5), wherein the compound semiconductor layer has a contact layer in contact with the electrode layer.

(7) The light emitting diode according to any one of (1) to (6), wherein the mesa structure part includes all of the active layer and a part or all of the reflective layer.

(8) The light emitting diode according to any one of (1) to (7), wherein the mesa structure is rectangular in plan view.

(9) The light-emitting diode according to (8), wherein each of the inclined side surfaces of the mesa structure portion is formed offset relative to an orientation flat of the substrate.

(10) The light emitting diode according to any one of (1) to (9), wherein the mesa structure has a height of 3 to 7 탆 and a width of the oblique side viewed from a plane is 0.5 to 7 탆.

(11) The light emitting diode according to any one of (1) to (10), wherein the light emitting hole is circular or elliptical in plan view.

(12) The light emitting diode according to (11), wherein the diameter of the light emitting hole is 50 to 150 占 퐉.

(13) The light emitting diode according to any one of (1) to (12), wherein the electrode layer has a bonding wire at a portion above the upper surface.

(14) The light emitting diode according to any one of (1) to (13), wherein the light emitting layer included in the active layer is composed of multiple quantum wells.

15, the light-emitting layer included in the active layer _{((Al X1 Ga 1 - X1} ) Y1 In 1 -Y1 P (0≤X1≤1, 0 <Y1≤1), (Al X2 Ga 1 - X2) As (0 ≤X2≤1), (in Ga _{1 X3 - X3)} as (0≤X3≤1),), a light emitting diode according to any one of any one that comprises the features (1) to (14) of.

(16) a supporting structure part having a top surface and a side surface, and a mesa structure part arranged on the supporting structure part and having a sloping side surface and a top surface, wherein a compound semiconductor layer including a reflective layer and an active layer is formed on a substrate A mesa structure section in which the first wet etching is performed on the compound semiconductor layer and a cross sectional area in a horizontal direction is continuously reduced toward the top surface; and a mesa structure section formed by forming a top surface of a support structure section disposed around the mesa structure section A step of performing a second wet etching along a cutting line for fragmenting to form an inclined portion on a side surface of the supporting structure portion; and a step of forming an inclined portion on the inclined portion and at least a part of the upper surface, And a conductive window for exposing a part of the surface of the compound semiconductor layer to the top surface of the mesa structure, A step of forming a protective film on the mesa structure and directly contacting the surface of the compound semiconductor layer exposed from the power window and covering at least part of the protective film formed on the top surface, And a step of forming an electrode layer as a continuous film so as to have an injection hole.

(17) The method according to (17), wherein the first and second wet etching are performed using at least one selected from the group consisting of a phosphoric acid / hydrogen peroxide mixture, an ammonia / hydrogen peroxide mixture, a bromomethane mixture and potassium iodide / (16). &Lt; / RTI &gt;

According to the light emitting diode of the present invention, since the support structure having the upper surface and the side surface and the mesa structure having the inclined side surface and the steep surface are disposed on the support structure, high light output is obtained and It is possible to efficiently introduce light into optical parts and the like.

In addition, the mesa structure portion is formed by wet etching and the mesa structure portion is formed so that the cross-sectional area in the horizontal direction is continuously small toward the top face, wherein the support structure portion and the mesa structure portion are formed of at least And at least a portion of the upper surface, at least an inclined portion of the side surface, an inclined side surface, and at least a peripheral region of the top surface, and at least a portion of the peripheral region And the electrode layer directly contacts the surface of the compound semiconductor layer exposed from the power window and at least partially covers a part of the protective film formed on the upper surface of the compound semiconductor layer, Which is a continuous film formed so as to have a light emitting hole on the top surface of the substrate Since the protective film and the electrode film thereon are easily formed on the side surface, a continuous film having a uniform film thickness is formed on the side surface, so that leakage and conduction failure due to the discontinuous film are prevented, and stable and high-luminance light emission is provided It is possible. Such an effect is exhibited when a mesa structure portion having an inclined side surface formed by wet etching is provided, and is an effect obtained irrespective of the lamination structure inside the light emitting diode and the structure of the substrate.

The support structure includes at least a portion of the reflective layer, and the inclined portion is formed by wet etching and extends from the upper surface to the substrate side at least over the reflective layer. In the horizontal direction including the inclined portion The protective film at least partially covers at least a part of the upper surface, at least the inclined part of the side surface, the inclined side surface, and the peripheral area of the top surface. Therefore, Since the side surface of the reflective layer is covered with a protective film, the side surface of the reflective layer is prevented from being in contact with the atmosphere or moisture and deteriorated, thereby achieving high reliability and long life. Such an effect is exhibited when a mesa structure portion having an inclined side surface formed by wet etching is provided, and is an effect obtained irrespective of the lamination structure inside the light emitting diode and the structure of the substrate.

According to the light emitting diode of the present invention, by employing the configuration in which the reflective layer is a DBR reflective layer, light emission with a narrow emission spectrum width becomes possible. Further, by employing a configuration in which the upper DBR reflecting layer is further provided on the side opposite to the substrate of the active layer, the emission spectrum line width is narrow and the directivity of the emitted light is high, and high-speed response becomes possible.

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According to the light emitting diode of the present invention, the inclined portion comprises two or more inclined portions, and each of the cross sectional areas in the horizontal direction including the inclined portions is continuously small toward the top surface, and the sectional area in the horizontal direction including the inclined portion close to the top surface It is easier to form the protective film and the electrode film thereon than on the vertical side, so that a continuous film is formed with a uniform film thickness, so that there is no leakage or poor conduction due to the discontinuous film , Stable and high-luminance light emission can be provided.

According to the light emitting diode of the present invention, it is possible to prevent leakage of light emitted from the active layer through the electrode layer and / or the protective film and out of the device, by employing the structure including the light leakage preventing film on the electrode layer and / or the protective film.

According to the light emitting diode of the present invention, by employing the structure in which the compound semiconductor layer has the contact layer in contact with the electrode layer, the contact resistance of the ohmic electrode can be lowered, and low voltage driving becomes possible.

According to the light emitting diode of the present invention, since the mesa structure part adopts a configuration including both the active layer and a part or all of the reflective layer, the light emission is entirely generated in the mesa structure part, and the light extraction efficiency is improved.

According to the light emitting diode of the present invention, when the mesa structure is rectangular in plan view, it is possible to suppress the change of the mesa shape according to the etching depth due to the influence of the anisotropy in the wet etching at the time of manufacturing, Since it is easy to control the curved surface area, a high-precision dimension shape is obtained.

According to the light emitting diode of the present invention, by employing the configuration in which each inclined side face of the mesa structure portion is offset relative to the orientation flat of the substrate, the influence of the anisotropy due to the substrate orientation on the four sides constituting the rectangular mesa structure portion The mesa shape and the gradient are uniformly obtained.

According to the light emitting diode of the present invention, by adopting a configuration in which the height of the mesa structure portion is 3 to 7 mu m and the width of the oblique side surface viewed from the plane is 0.5 to 7 mu m, It is possible to form a continuous film with a uniform film thickness, so that leakage and conduction failure due to the discontinuous film can be avoided, and stable, high-luminance light emission can be provided.

According to the light emitting diode of the present invention, by adopting a circular or elliptical configuration when the light emitting orifice is viewed in plan view, it is easy to form a uniform contact area as compared with a structure having an angle of a rectangle or the like, Can be suppressed. It is also suitable for bonding to fibers or the like on the light receiving side.

According to the light emitting diode of the present invention, by adopting the structure in which the diameter of the light emitting hole is 50 to 150 mu m, the current density in the mesa structure portion becomes higher at less than 50 mu m, the output becomes saturated at low current, , It is difficult to diffuse the current to the entire mesa structure part, so that the problem that the luminous efficiency with respect to the injection current is lowered is prevented.

According to the light emitting diode of the present invention, wire bonding is performed on the upper surface to which a sufficient load (and ultrasonic wave) is applied by employing the structure having the bonding wire on the upper surface of the electrode layer, have.

According to the light emitting diode of the present invention, by employing the configuration in which the light emitting layer included in the active layer is composed of multiple quantum wells, light emission excellent in monochromaticity can be performed.

According to the method for manufacturing a light emitting diode of the present invention, the first wet etching is performed on the compound semiconductor layer to form a mesa structure section in which the cross sectional area in the horizontal direction is continuously reduced toward the top surface, and a mesa structure section arranged around the mesa structure section A step of forming an upper surface of the support structure part, a step of performing a second wet etching along the cutting line for discretization to form an inclined part on the side surface of the support structure part, and a step of covering at least a part of the inclined part and the upper surface, A step of forming a protective film on the support structure and the mesa structure so as to have a current window exposing a part of the surface of the compound semiconductor layer on the top surface of the compound semiconductor layer, At least a part of the protective film formed on the mesa structure is covered with a light injection hole It is possible to efficiently introduce the light emitted by the light emitting device with high light output and to the optical parts and the like, and to provide a protective film And the electrode film thereon are easily formed, a continuous film is formed with a uniform film thickness. Therefore, it is possible to manufacture a light-emitting diode which is free from leakage due to a discontinuous film or defective conduction, and is capable of providing stable, high- have. When the filler structure is formed by the conventional anisotropic dry etching, the side surface is formed vertically, but the side surface can be formed as a gentle inclined side surface by forming the mesa structure portion by (first) wet etching. Further, by forming the mesa structure portion by (first) wet etching, the formation time can be shortened as compared with the case where the filler structure is formed by the conventional dry etching.

In addition, since the second wet etching is performed along the cutting line for discretization to form the inclined portion on the side surface of the supporting structure portion and the step of forming the protective film covering the inclined portion, the side surface is in contact with the atmosphere or moisture It is possible to manufacture a light emitting diode which is prevented from being deteriorated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional schematic diagram of a light emitting diode according to an embodiment of the present invention. FIG.
2 is a perspective view of a light emitting diode which is an embodiment of the present invention;
3 is an electron micrograph showing a cross section of an inclined slope of a light emitting diode according to an embodiment of the present invention.
4 is a cross-sectional schematic diagram of an active layer of a light emitting diode which is an embodiment of the present invention.
5 is a cross-sectional schematic diagram of a light emitting diode according to another embodiment of the present invention.
6 is a cross-sectional schematic diagram of a light emitting diode which is still another embodiment of the present invention.
7 is a cross-sectional view for explaining a method of manufacturing a light emitting diode according to an embodiment of the present invention.
8 is a cross-sectional view illustrating a method of manufacturing a light emitting diode according to an embodiment of the present invention.
9 is a graph showing the relationship between the depth and the width of the wet etching with respect to the etching time.
10 is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode according to an embodiment of the present invention.
11 is a graph showing a measurement result of an optical spectrum immediately above a light emitting diode.
12 is a graph showing the measurement result of the directivity of emitted light.
13 is a cross-sectional view of a conventional light emitting diode.

Hereinafter, a light emitting diode to which the present invention is applied and a method of manufacturing the same will be described in detail with reference to the accompanying drawings. The drawings used in the following description may be enlarged and illustrated as a part for convenience in order to facilitate understanding of the characteristics, and the dimensional ratios and the like of the respective components are not necessarily the same as actual ones. In addition, the materials and dimensions exemplified in the following description are merely examples, and the present invention is not limited to them, but can be appropriately changed without departing from the gist of the present invention. Further, a layer not described below may be provided within a range not to impair the effect of the present invention.

[Light Emitting Diode (First Embodiment)]

1 is a cross-sectional schematic diagram of a resonator type light emitting diode which is an example of a light emitting diode to which the present invention is applied. 2 is a perspective view of a light emitting diode formed on a wafer substrate including the light emitting diode shown in Fig.

Hereinafter, a light emitting diode of an embodiment to which the present invention is applied will be described in detail with reference to Figs. 1 and 2. Fig.

A light emitting diode 100 shown in Fig. 1 is a light emitting diode having a compound semiconductor layer including a reflective layer 2 and an active layer 3 on a substrate 1 and has a top surface 6a and a side surface 6b A supporting structure 6 and a mesa structure 7 arranged on the supporting structure 6 and having an inclined side face 7a and a top face 7b and the supporting structure 6 comprises at least a reflective layer 2 The side face 6b is formed by wet etching and has an inclined portion 6ba extending from the upper face 6a to the substrate 1 side at least to a position exceeding the reflective layer 2 And a cross sectional area in the horizontal direction including the inclined portion 6ba is continuously reduced toward the upper surface 6a and the mesa structure portion 7 includes at least a part of the active layer 3 , Its inclined side surface (7a) is formed by wet etching, and the cross sectional area in the horizontal direction The support structure 6 and the mesa structure 7 are each formed in such a manner that at least a part thereof is covered in order by the protective film 8 and the electrode film 9, The protective film 8 covers at least a part of the upper surface 6a and at least the inclined portion 6ba and the inclined side surface 7a of the side surface 6b and the peripheral region 7ba of the top surface 7b, And a power window 8b for exposing a part of the surface of the compound semiconductor layer (contact layer 5) on the inner side of the peripheral region 7baa as viewed in plan view. The electrode layer 9 has a structure in which the compound A continuous film formed to directly contact the surface of the semiconductor layer and to cover at least a part of the protective film 8 formed on the upper surface 6a and to have a light emitting hole on the top surface 7b of the mesa structure portion 7, (2) is a DBR reflecting layer (lower DBR reflecting layer), and an upper DBR reflecting layer 4 is provided on the side of the active layer 3 opposite to the substrate 1 , And the compound semiconductor layer has a contact layer (5) contacting the electrode layer (9).

The side surface 6b of the supporting structure portion 6 is inclined to the inclined portion 6ba (in this embodiment, the side surface of the reflective layer 2 and the side surface of the substrate 1 in this embodiment) and the side surface portion 6bb of the substrate .

A light leakage preventing film 24 is provided on the inclined portion 6ba of the side surface 6b of the supporting structure portion 6 with a protective film interposed therebetween.

The mesa structure portion 7 of the present embodiment is rectangular in plan view and the light emission hole 9b of the electrode layer 9 is circular when viewed in plan view. The mesa structure 7 is not limited to a rectangular shape in plan view, and the light emission hole 9b is not limited to a circular shape in plan view. Further, a back electrode 10 (see Fig. 5) is formed on the lower surface side of the substrate 1. In Fig.

2, a plurality of light emitting diodes 100 are fabricated on a wafer-shaped substrate, and streets 21 (dotted lines 22 are streets 21) for each light emitting diode, Along the longitudinal centerline of the base material). That is, by cutting a laser, a blade, or the like on the portion of the street 21 along the dotted line 22, it is possible to cut each light emitting diode.

The mesa structure 7 is structured so as to protrude upward with respect to the upper surface 6a and has the inclined side surface 7a and the steep surface 7b as the outer surface. In the case of the example shown in Fig. 1, the oblique side face 7a is an electrode layer (surface electrode layer) formed by covering the entire upper layer of the active layer 3, the upper DBR layer 4 and the sloping end face of the contact layer 5 with a protective film The top surface 7b is composed of the surface of the portion 8d covering the center portion of the protective film 8 and the surface of the electrode layer 9 (portions 9ba, 9bb and 9d).

The mesa structure 7 of the present invention includes at least a part of the active layer 3 inside thereof.

In the case of the example shown in Fig. 1, the mesa structure 7 includes the contact layer 5, the upper DBR layer 4, and the entire layer of the active layer 3 in the mesa structure 7. The mesa structure portion 7 may include only a part of the active layer 3, but it is preferable that the entire layer of the active layer 3 is included in the mesa structure portion 7. All the light emitted from the active layer 3 is generated in the mesa structure portion, and the light extraction efficiency is improved. In addition, a part of the lower DBR layer 2 may be included in the mesa structure portion 7.

The mesa structure 7 is formed such that the inclined side face 7a is formed by wet etching and the sectional area in the horizontal direction is continuously reduced from the substrate 1 side to the top face 7b Respectively. Since the inclined side surface 7a is formed by wet etching, it is formed in a downward convex shape. It is preferable that the height h of the mesa structure 7 is 3 to 7 占 퐉 and the width w of the inclined side face 7a in the plan view is 0.5 to 7 占 퐉. In this case, since the side surface of the mesa structure portion 7 is not a vertical or steep slope but a gentle slope, it is easy to form the protective film or the electrode metal film with a uniform film thickness, and there is no possibility of becoming a discontinuous film This is because there is no leakage or conduction defect caused by the discontinuous film, and stable, high-luminance light emission can be provided. When wet etching is performed until the height exceeds 7 mu m, the inclined side surfaces tend to become overhanging shapes (reverse tapered shapes), which is not preferable. In the overhanging shape (reverse taper shape), it is more difficult to form the protective film or the electrode film with a uniform film thickness without discontinuous portions than in the case of the vertical side.

In this specification, the height h refers to the distance from the surface of the electrode film 9 (the portion indicated by reference numeral 9c) formed through the protective film on the upper surface 6a to the surface of the electrode film 9a covering the portion 8ba of the protective film 8 (Refer to FIG. 1) in the vertical direction to the surface of the substrate 9 (portion 9ba). The width w refers to the width of the electrode film 9 (the portion indicated by reference numeral 9a) connected to the edge of the electrode film 9 (portion 9ba) covering the portion 8ba of the protective film 8 Means a distance in the horizontal direction to the lowest edge (see Fig. 1).

3 is an electron micrograph of a cross section in the vicinity of the mesa structure portion 7.

FIG example layer structure shown in 3, the contact layer is made of Al _{0 .3} Ga _{0 .7} As, the configuration of the layer embodiment similar to those of a thickness is below than the 3㎛ point.

Since the mesa structure portion of the present invention is formed by wet etching, the increase rate of the horizontal cross-sectional area (or width or diameter) of the mesa structure portion increases from the top surface side toward the substrate side Respectively. By this shape, it can be determined that the mesa structure portion is formed by wet etching instead of dry etching.

In the example shown in Fig. 3, the height h was 7 占 퐉 and the width w was 3.5 to 4.5 占 퐉.

The mesa structure 7 preferably has a rectangular shape in plan view. This is because the influence of the anisotropy in the wet etching at the time of manufacturing suppresses the change of the mesa shape according to the etching depth and facilitates the control of the area of each face of the mesa structure portion, so that a highly accurate dimensional shape can be obtained.

As shown in Figs. 1 and 2, the position of the mesa structure 7 in the light emitting diode is preferably shifted to one side in the longitudinal direction of the light emitting diode for miniaturization of the device. Since the upper surface 6a needs to be wide enough to be used for mounting a bonding wire (not shown), there is a limit in narrowing it and the mesa structure 7 is biased to the other side, (6a) can be minimized, and the device can be miniaturized.

The supporting structure part 6 is arranged at the lower part of the mesa structure part 7 and has an upper surface 6a and a side surface 6b as an outer surface. The side face 6b includes an inclined portion 6ba which is formed by wet etching and extends from the upper face 6a toward the substrate 1 side at least to a position exceeding the reflective layer 2. [ The supporting structure portion 6 is formed such that the sectional area in the horizontal direction including the inclined portion 6ba is continuously reduced toward the upper surface 6a (upper side). The cross sectional area in the horizontal direction including the side surface excluding the inclined portion 6ba remains unchanged.

When the wet etching is performed until the height of the inclined portion 6ba exceeds 7 占 퐉, the overhanging shape (reverse tapered shape) tends to be formed. Therefore, the inclined portion 6ba is preferably 7 占 퐉 or less.

The inclined portion 6ba may be composed of a plurality of inclined portions. In this case, the cross-sectional areas in the horizontal direction including the inclined portions are continuously small toward the upper surface (upper side), and the cross-sectional areas in the horizontal direction including the inclined portions close to the upper surface . In particular, when the height of the inclined portion 6ba exceeds 7 占 퐉, as in the case of forming the mesa structure portion, if the inclined portion is formed by wet etching, the overhanging shape (reverse tapered shape) It is preferable to form the inclined portion 6ba with a plurality of inclined portions of 7 mu m or less.

Further, when the inclined portion is formed deeply (high) by wet etching, the etching progresses also in the lateral direction, so that the mesa structure portion is reduced and the light emitting area is reduced. In addition, There is a problem in that the etching rate of the vertical and the horizontal is different from each other due to the effect of the anisotropy of the etching. Therefore, there is a problem that only one direction is formed deeper. As shown in Fig.

The upper surface 6a is a portion arranged around the mesa structure 7. [ In the present invention, since the wire bonding is performed at a portion located on the upper surface of the electrode layer capable of applying a sufficient load (and ultrasonic waves) instead of the mesa structure portion 7, wire bonding with high bonding strength can be realized.

A protective film 8 and an electrode layer (surface electrode layer) 9 are formed in this order on the upper surface 6a and a bonding wire (not shown) is provided on the electrode layer 9 on the upper surface 6a. The material disposed immediately below the protective film 8 on the upper surface 6a is determined by the internal structure of the mesa structure 7. [ 1, the inside of the mesa structure portion 7 includes the contact layer 5, the upper DBR layer 4, and the entire layer of the active layer 3, The material disposed immediately under the protective film 8 of the upper surface 6a is the material of the uppermost surface of the lower DBR layer because the uppermost surface of the lower DBR layer is disposed directly below the protective film 8 of the upper surface 6a.

The protective film 8 has a portion 8c covering at least a part of the upper surface 6a (including a portion 8cc covering the upper surface on the opposite side with the mesa structure portion 7 sandwiched therebetween) And has a portion 8f covering the inclined portion 6ba, a portion 8a covering the inclined side face 7a and a portion 8ba covering the peripheral region 7ba of the top face 7b, And an energizing window 8b for exposing a part of the surface of the compound semiconductor layer on the inner side of the peripheral region 7ba.

The power window 8b of the present embodiment has a portion 8ba positioned below the peripheral region 7ba and a central portion of the surface of the contact layer 5 on the top face 7b of the mesa structure portion 7 And exposes a region between two concentric circles having different diameters between the portions located below the covering portion 8d.

Since the protective film 8 has the portion 8f covering at least the inclined portion 6ba of the side surface 6b and covers the side surface of the reflecting layer of the supporting structure portion, the side surface of the reflecting layer is deteriorated by contact with air or moisture So that high reliability and long life can be achieved.

The first function of the protective film 8 is to arrange a lower layer of the surface electrode layer 9 so as to narrow the region where the light emission is generated and the range of the light to be taken out so that a current flows between the surface electrode layer 9 and the back electrode 10 To limit the area. That is, after the protective film 8 is formed, a surface electrode layer is formed on the entire surface including the protective film 8, and then the surface electrode layer is patterned. In the portion where the protective film 8 is formed, The current does not flow between the back electrodes 10 even if the back electrode 10 is not used. And the power window 8b of the protective film 8 is formed at a place where a current is to be passed between the back electrode 10 and the back electrode.

Therefore, if the power window 8b is formed on a part of the top face 7b of the mesa structure portion 7 so as to have the first function, the shape and position of the power window 8b are the same as in Fig. 1 Location.

The second function of the protective film 8 is not an essential function unlike the first function. In the case of the protective film 8 shown in Fig. 1, as the second function, Is disposed on the surface of the contact layer 5 in the hole 9a to protect the surface of the contact layer 5 from which light can be extracted and from which the light is extracted.

In the second embodiment to be described later, the light is taken out directly from the light emitting orifice 9b without passing through the protective film without the protective film below the light emitting hole, and does not have the second function.

As the material of the protective film 8, a known material can be used as the insulating layer, but a silicon oxide film is preferable in that a stable insulating film can be easily formed.

Further, in the present embodiment, since the light is extracted through the protective film 8 (8d), the protective film 8 needs to have transparency.

The thickness of the protective film 8 is preferably 0.3 to 1 mu m. If the thickness is less than 0.3 mu m, insulation is not sufficient. If the thickness is more than 1 mu m, it takes a long time to form.

The electrode layer (surface electrode layer) 9 has a portion 9bb (hereinafter referred to as &quot; contact portion &quot;, as appropriate) which covers at least part of the surface of the compound semiconductor layer exposed from the current- A portion 9c covering the portion 8c covering at least a part of the upper surface 6a of the protective film 8 and a portion 9c covering the portion 8a covering the oblique side surface 7a of the protective film 8 A portion 9ba covering the portion 8ba of the protective film 8 covering the peripheral region 7ba of the top face 7b of the mesa structure portion 7 and a portion 9ba covering the peripheral region 7ba of the mesa structure portion 7, (9d) covering the outer peripheral edge portion of the portion (8d) covering the central portion of the top surface (7b) of the protective film (8) in the protective film (7b).

The first function of the electrode layer (surface electrode layer) 9 is to flow a current with the back electrode 10, and the second function is to limit the range in which the emitted light is emitted. In the case of the example shown in Fig. 1, the first function is carried out by the contact portion 9bb, and the second function is by the portion 9d covering the outer peripheral portion of the portion 8d covering the central portion.

And a non-transmitting protective film may be used for the second function, and the protective film may be used as the protective film.

The electrode layer 9 may cover the whole of the protective film 8 on the upper surface 6a or cover a part of the protective film 8, but it is preferable that the electrode layer 9 covers as wide a range as possible in order to suitably set the bonding wires. From the viewpoint of cost reduction, it is preferable not to cover the electrode layer in the street 21 when cutting each light emitting diode as shown in Fig.

This electrode layer 9 contacts the contact layer 5 only in the contact portion 9bb on the top face 7b of the mesa structure portion 7 so that the electrode layer 9 and the back electrode 10 are in contact with the contact portion 9bb ) And the back electrode (10). As a result, in the light emitting layer 13, current is concentrated in a region overlapping the light emitting orifice 9b in plan view, and light is concentrated in the range, so that light can be efficiently extracted.

A known electrode material can be used as the material of the electrode layer 9, but AuBe / Au is most preferable in that a good ohmic contact can be obtained.

The thickness of the electrode layer 9 is preferably 0.5 to 2.0 占 퐉. When the thickness is less than 0.5 mu m, it is difficult to obtain a uniform and good ohmic contact, and the strength and thickness at the time of bonding are insufficient.

The light leakage preventing film 24 prevents the light emitted from the active layer from leaking out of the device through the protective film 8f on the inclined portion 6ba of the side surface 6b of the supporting structure 6. [

The light leakage preventing film 24 shown in Fig. 1 is provided only on a part of the upper surface 6a on the inclined portion 6ba (via the protective film 8f) and on the electrode film 9c of the upper surface 6a, Or may be formed on another portion of the upper surface 6a of the substrate 6 or on the mesa structure 7.

A known reflective material can be used as the material of the light leakage preventing film 24, but AuBe / Au is preferable because it can be formed at the same time as the electrode layer 9. [

In this embodiment, a protective film 8d (8) is formed below the light emitting hole 9b, and the light emitting hole 9b (8b) is formed on the top face of the mesa structure portion 7 through the protective film 8d And the light is taken out from the light source.

The shape of the light emission hole 9b is preferably circular or elliptical in plan view. It is easy to form a uniform contact area as compared with a structure having an angle of, for example, a rectangle, and the occurrence of current concentration and the like at the corner can be suppressed. Further, it is suitable for bonding to fibers and the like on the light receiving side.

The diameter of the light emission hole 9b is preferably 50 to 150 mu m. If the thickness is less than 50 mu m, the current density at the injection portion becomes high and the output becomes saturated at low current. On the other hand, when the thickness exceeds 150 mu m, current diffusion to the entire injection portion becomes difficult, to be.

As the substrate 1, for example, a GaAs substrate can be used.

When a GaAs substrate is used, a commercially available single crystal substrate manufactured by a known manufacturing method can be used. The epitaxially grown surface of the GaAs substrate is preferably smooth. The plane orientation of the surface of the GaAs substrate is easy to grow epitaxially, and a substrate which is off within ± 20 ° from (100) plane and (100) which are mass-produced is preferable in terms of quality stability. Further, it is more preferable that the range of the plane orientation of the GaAs substrate is 15 degrees off ± 5 degrees from the (100) direction to the (0-1-1) direction.

The dislocation density of the GaAs substrate is preferably low in order to improve the crystallinity of the lower DBR layer 2, the active layer 3, and the upper DBR layer 4. Concretely, for example, it is suitable that it is not more than 10,000 cm- ² , preferably not more than 1,000 cm- ² .

The GaAs substrate may be n-type or p-type. The carrier concentration of the GaAs substrate can be appropriately selected from the desired electric conductivity and device structure. For example, when the GaAs substrate is Si-doped n-type, it is preferable that the carrier concentration is in the range of 1 × 10 ¹⁷ to 5 × 10 ¹⁸ cm ^-3 . In contrast, when the GaAs substrate is a p-type doped with Zn, the carrier concentration is preferably in the range of 2 x 10 ¹⁸ to 5 x 10 ¹⁹ cm ^-3 .

The thickness of the GaAs substrate has an appropriate range depending on the size of the substrate. If the thickness of the GaAs substrate is thinner than an appropriate range, the compound semiconductor layer may be broken during the manufacturing process. On the other hand, if the thickness of the GaAs substrate is larger than an appropriate range, the material cost increases. For this reason, when the substrate size of the GaAs substrate is large, for example, when the diameter is 75 mm, a thickness of 250 to 500 탆 is preferable in order to prevent cracking during handling. Similarly, when the diameter is 50 mm, the thickness is preferably 200 to 400 탆, and when the diameter is 100 mm, the thickness is preferably 350 to 600 탆.

As described above, by increasing the thickness of the substrate in accordance with the substrate size of the GaAs substrate, the warp of the compound semiconductor layer attributed to the active layer 3 can be reduced. As a result, the temperature distribution during the epitaxial growth becomes uniform, so that the wavelength distribution in the plane of the active layer 3 can be reduced. The shape of the GaAs substrate is not particularly limited to a circle, and may be a rectangular shape or the like.

A well-known functional layer can be timely added to the structure of the reflective layer (the lower DBR layer 2 and the compound semiconductor layers (the active layer 3, the upper DBR layer 4, and the contact layer 5). A current diffusion layer for diffusing a device driving current in a planar manner in the front half of the light emitting portion and a current blocking layer or a current confinement layer for limiting a region through which a device driving current flows can be provided.

The reflective layer (lower DBR layer) and the compound semiconductor layer formed on the substrate 1 are formed by sequentially laminating the lower DBR layer 2, the active layer 3, and the upper DBR layer 4.

A DBR (Distributed Bragg Reflector) layer is formed by alternately laminating two types of layers having different film thicknesses of? / (4n) (?: Wavelength of light to be reflected in vacuum, n: refractive index of layer material) Layer film. As for the reflectance, if the difference in refractive index between the two kinds is large, a high reflectance is obtained in a multilayer film having a relatively small number of layers. It is characterized not to be reflected on any one surface like a normal reflective film but to reflect on the basis of the light interference phenomenon as a whole of the multilayer film.

The material of the DBR layer is preferably transparent to the light emission wavelength, and it is preferable that the material is selected so that the difference in the refractive index of the two kinds of materials constituting the DBR layer becomes large.

It is preferable that the lower DBR layer 2 is formed by alternately stacking 10 to 50 pairs of two kinds of layers having different refractive indexes. When the number of pairs is 10 or less, the reflectance is too low, which does not contribute to the increase of the output. Even if the number of pairs is 50 or more, the increase of the additional reflectance is small.

The lower layers of different two kinds of refractive index constituting the DBR layer (2), two kinds of different compositions _{(Al Xh Ga 1 - Xh)} Y3 In 1 -Y3 P (0 <Xh≤1, Y3 = 0.5), (Al Ga _{1 Xl - Xl)} in _{1 Y3 - Y3} P; a pair of 0≤Xl <1, Y3 = 0.5) , of both the Al composition difference ΔX = xh-xl combination becomes greater than or equal to than 0.5 and , or a different combination of two or, or a composition of GaInP and AlInP kind of _{Al xl Ga 1 -xl as (0.1≤xl≤1} ), Al xh Ga 1 - a pair of _xh as (0.1≤xh≤1), both Is selected from any one of the combinations in which the composition difference? X = xh-xl is greater than or equal to 0.5 is preferable in that a high reflectance can be efficiently obtained.

The combination of AlGaInP having different compositions is preferable because it does not contain As, which is likely to cause crystal defects. GaInP and AlInP can take the largest refractive index difference among them, so that the number of reflection layers can be reduced, It is preferable since it is simple. Further, AlGaAs has an advantage that it is easy to take a large refractive index difference.

Since the upper DBR layer 4 can also use the same layer structure as the lower DBR layer 2, it is necessary to transmit light through the upper DBR layer 4, so that the reflectance of the upper DBR layer 4 . Specifically, when the lower DBR layer 2 is made of the same material as the lower DBR layer 2, it is preferable that 3 to 10 pairs of two kinds of layers having different refractive index are alternately stacked so that the number of layers is smaller than that of the lower DBR layer 2. [ When the number of pairs is equal to or more than 11, the amount of light transmitted through the upper DBR layer 4 is excessively lowered because the reflectance is too low to contribute to an increase in output.

The light emitting diode of the present invention is characterized in that the active layer 3 is disposed between the low DBR layer 4 and the low DBR layer 2 and the light emitted from the active layer 3 is incident on the upper DBR layer 4, And the lower DBR layer 2 so as to position a fold of the standing wave in the light emitting layer. Thus, the light emitting diode is higher in directivity than the conventional light emitting diode without laser oscillation, and is a high efficiency light emitting diode.

4, the active layer 3 includes a lower cladding layer 11, a lower guide layer 12, a light emitting layer 13, an upper guide layer 14, and an upper cladding layer 15 sequentially stacked Consists of. In other words, the active layer 3 has a function of forming a lower cladding layer 11 (a second cladding layer) which is disposed in opposition to the lower side and the upper side of the light emitting layer 13, Called double-hetero structure (abbreviation: DH) structure including the lower cladding layer 12, the upper guide layer 14, and the upper cladding layer 15 is preferable for obtaining high intensity luminescence.

As shown in Fig. 4, the light emitting layer 13 can constitute a quantum well structure in order to control the light emission wavelength of the light emitting diode (LED). That is, the light emitting layer 13 may have a multilayer structure (laminated structure) of the well layer 17 and the barrier layer 18 having barrier layers (also referred to as barrier layers) 18 at both ends.

The layer thickness of the light emitting layer 13 is preferably in the range of 0.02 to 2 mu m. The conduction type of the light emitting layer 13 is not particularly limited, and both undoped, p-type, and n-type can be selected. In order to increase the luminous efficiency, it is preferable to use an undoped crystal having good crystallinity or a carrier concentration of less than 3 × 10 ¹⁷ cm ^-3 .

As the material of the well layer 17, a known well layer material can be used. For example, AlGaAs, InGaAs, and AlGaInP can be used.

The layer thickness of the well layer 17 is preferably in the range of 3 to 30 nm. More preferably, it is in the range of 3 to 10 nm.

As the material of the barrier layer 18, it is preferable to select a material suitable for the material of the well layer 17. It is preferable that the composition is such that the band gap becomes larger than that of the well layer 17 in order to prevent the absorption in the barrier layer 18 and increase the luminous efficiency.

For example, when AlGaAs or InGaAs is used as the material of the well layer 17, AlGaAs or AlGaInP is preferable as the material of the barrier layer 18. [ When AlGaInP is used as the material of the barrier layer 18, since it does not contain As which is easy to make defects, it has high crystallinity and contributes to high output.

As a material for the well layer ₍₁₇₎ when using the _{(Al X1 Ga 1 X1) Y1} In 1 -Y1 P (0≤X1≤1, 0 <Y1≤1), Al composition than a material of the barrier layer 18 above or _{(Al X4 Ga 1 - X4)} Y1 In 1 -Y1 P (0≤X4≤1, 0 <Y1≤1, X1 <X4) or the well layer _{(Al X1 Ga 1 - X1)} Y1 In 1-Y1 P ( 1 < / = 1, 0 &lt; Y1 &lt; / = 1).

The layer thickness of the barrier layer 18 is preferably equal to or thicker than the layer thickness of the well layer 17. By enlarging the thickness in the layer thickness range in which the tunnel effect occurs, the enlargement of the gap between the well layers due to the tunnel effect is suppressed, the effect of confinement of the carriers is increased, the probability of the light-emitting recombination of electrons and holes is increased, .

The number of pairs for alternately stacking the well layer 17 and the barrier layer 18 in the multi-layer structure of the well layer 17 and the barrier layer 18 is not particularly limited, but is preferably 2 or more and 40 or less . That is, the active layer 11 preferably contains 2 to 40 well layers 17. Here, the preferable range of the light emitting efficiency of the active layer 11 is that the well layer 17 has five or more layers. On the other hand, since the well layer 17 and the barrier layer 18 have low carrier concentration, the forward voltage (V _F ) increases when the pair is formed in many pairs. For this reason, the number of pairs is preferably 40 or less, more preferably 20 or less.

The lower guide layer 12 and the upper guide layer 14 are formed on the lower surface and the upper surface of the luminescent layer 13, respectively, as shown in Fig. Specifically, the lower guide layer 12 is formed on the lower surface of the light emitting layer 13, and the upper guide layer 14 is formed on the upper surface of the light emitting layer 13.

As the material of the lower guide layer 12 and the upper guide layer 14, a well-known compound semiconductor material can be used, and it is preferable to select a material suitable for the material of the light emitting layer 13. For example, AlGaAs and AlGaInP can be used.

For example, when AlGaAs or InGaAs is used as the material of the well layer 17 and AlGaAs or AlGaInP is used as the material of the barrier layer 18, the material of the lower guide layer 12 and the upper guide layer 14 may be AlGaAs Or AlGaInP is preferable. When AlGaInP is used as the material of the lower guide layer 12 and the upper guide layer 14, since it does not contain As which is easy to make defects, the crystallinity is high and contributes to high output. As a material for the well layer (17) _- than Al composition as the material of the (Al _X1 Ga _{1 X1) Y1 -Y1} P ₁ In the case of using the (0≤X1≤1, 0 <Y1≤1), the guide layer 14 is above or _{(Al X4 Ga 1 - X4)} Y1 In 1 -Y1 P (0≤X4≤1, 0 <Y1≤1, X1 <X4) or the well layer _{(Al X1 Ga 1 - X1)} Y1 In 1-Y1 P ( 1 < / = 1, 0 &lt; Y1 &lt; / = 1).

The lower guide layer 12 and the upper guide layer 14 are formed to reduce the propagation of defects of the lower clad layer 11 and the upper clad layer 15 and the active layer 11, respectively. Therefore, the layer thickness of the lower guide layer 12 and the upper guide layer 14 is preferably 10 nm or more, more preferably 20 nm to 100 nm.

The conduction type of the lower guide layer 12 and the upper guide layer 14 is not particularly limited, and both undoped, p-type and n-type can be selected. In order to increase the luminous efficiency, it is preferable to use an undoped crystal having good crystallinity or a carrier concentration of less than 3 × 10 ¹⁷ cm ^-3 .

The lower clad layer 11 and the upper clad layer 15 are formed on the lower surface of the lower guide layer 12 and the upper surface of the upper guide layer 14, respectively, as shown in Fig.

As the material of the lower clad layer 11 and the upper clad layer 15, a well-known compound semiconductor material can be used, and it is preferable to select a material suitable for the material of the light-emitting layer 13. For example, AlGaAs and AlGaInP can be used.

For example, when AlGaAs or InGaAs is used as the material of the well layer 17 and AlGaAs or AlGaInP is used as the material of the barrier layer 18, as the material of the lower clad layer 11 and the upper clad layer 15, AlGaAs Or AlGaInP is preferable. When AlGaInP is used as the material of the lower cladding layer 11 and the upper cladding layer 15, it does not contain As, which is easy to make defects, and therefore has high crystallinity and contributes to high output.

As a material for the well layer ₍₁₇₎ when using the _{(Al X1 Ga 1 X1) Y1} In 1 -Y1 P (0≤X1≤1, 0 <Y1≤1), than the Al composition as the material of the cladding layer 15 above or _{(Al X4 Ga 1 - X4)} Y1 In 1 -Y1 P (0≤X4≤1, 0 <Y1≤1, X1 <X4) or the well layer _{(Al X1 Ga 1 - X1)} Y1 In 1-Y1 P ( 1 < / = 1, 0 &lt; Y1 &lt; / = 1).

The lower clad layer 11 and the upper clad layer 15 are configured to have different polarities.

The carrier concentration and the thickness of the lower cladding layer 11 and the upper cladding layer 15 may be appropriately within a known range and it is preferable to optimize the conditions so that the luminous efficiency of the active layer 11 is high. Further, the lower cladding layer and the upper cladding layer may not be formed.

Further, by controlling the composition of the lower clad layer 11 and the upper clad layer 15, warping of the compound semiconductor layer 20 can be reduced.

The contact layer 5 is formed to reduce the contact resistance with the electrode. The material of the contact layer 5 is preferably a material having a band gap larger than that of the light emitting layer 13. The lower limit of the carrier concentration of the contact layer 5 is preferably 5 × 10 ¹⁷ cm ^-3 or more and more preferably 1 × 10 ¹⁸ cm ^-3 or more in order to lower the contact resistance with the electrode. The upper limit of the carrier concentration is preferably 2 x 10 &lt; ¹⁹ &gt; cm &lt; ^-3 &gt; or less at which crystallinity is likely to decrease. The thickness of the contact layer 5 is preferably 0.05 탆 or more. Although the upper limit value of the thickness of the contact layer 5 is not particularly limited, it is preferable that the upper limit of the thickness is 10 占 퐉 or less in order to set the expense for the epitaxial growth to an appropriate range.

The light emitting diode of the present invention can be incorporated in electronic devices such as lamps, backlights, cellular phones, displays, various kinds of panels, computers, game machines, lighting, and mechanical devices such as automobiles with their electronic devices incorporated therein.

[Light Emitting Diode (Second Embodiment)]

Fig. 5 is a schematic cross-sectional view showing another example of a resonator type light emitting diode which is an example of a light emitting diode to which the present invention is applied.

In the first embodiment, a protective film is formed below the light emission hole, and light is extracted from the light emission hole through the protective film on the top surface of the mesa structure. However, in the second embodiment, And the light is extracted directly from the light emitting orifice 9b without passing through the protective film without the protective film.

That is, in the resonator-type light emitting diode 200 according to the second embodiment, the protective film 28 includes at least a portion 28c of the upper surface 6a, at least an inclined portion 6ba of the side surface 6b, At least a portion of the surface of the compound semiconductor layer (contact layer 5) is exposed to the inside of the peripheral region 7ba when viewed in a plan view along with covering at least the peripheral region 7ba of the top face 7a and the peripheral region 7ba of the top face 7b And the energizing window 28b and the electrode layer 29 covers at least a part of the surface of the compound semiconductor layer exposed from the energizing window 28b and a part of the upper surface 6a, Exposing another portion 5a of the surface of the compound semiconductor layer (contact layer 5) while covering only a part of the surface of the compound semiconductor layer (contact layer 5) exposed from the energizing window 28b on the top surface of the compound semiconductor layer Is a continuous film formed on the protective film 28 so as to have an injection hole 29b.

5, the protective film 28 of the second embodiment has a portion 28c covering at least a part of the upper surface 6a (a portion covering the upper surface on the opposite side with the mesa structure portion 7 sandwiched therebetween A portion 28a covering at least the inclined portion 6ba of the side face 6b and a portion 28a covering the inclined side face 7a and a peripheral region 7ba of the top face 7b, And a power window 28b that exposes a part of the surface of the compound semiconductor layer (contact layer 5) on the inner side of the peripheral region 7ba when viewed in plan view. That is, the energizing window 28b exposes a portion of the surface of the compound semiconductor layer (contact layer 5) other than the portion located under the peripheral region 7ba on the top face 7b of the mesa structure portion 7. A protective film 28 is formed on a portion between the electrode layer 29 and the back electrode 10 where current is not applied, although an electrode layer (surface electrode layer) 29 is formed on the protective film 28.

Since the protective film 28 has the portion 28f covering at least the inclined portion 6ba of the side surface 6b and covers the side surface of the reflective layer of the supporting structure portion, the side surface of the reflective layer is deteriorated by contact with air or moisture So that high reliability and long life can be achieved.

5, the electrode layer (surface electrode layer) 29 of the second embodiment has a portion 29a covering the portion 28a covering the oblique side surface 7a of the protective film 28, A portion 29c covering the portion 28c covering at least a part of the upper surface 6a of the mesa structure portion 28 and a portion 29c covering the portion 28c covering the peripheral region 7ba of the mesa structure portion 7 in the protective film 28, A portion 29ba covering the portion of the compound semiconductor layer 28a covering the part of the protective film 28a and the portion 28b covering the portion of the protective film 28 at the top surface 7b of the mesa structure portion 7, (The contact layer 5).

In the electrode layer (surface electrode layer) 29 of the second embodiment, the portion 29bb is responsible for both the first function and the second function.

[Light Emitting Diode (Third Embodiment)]

The light emitting diode of the third embodiment to which the present invention is applied differs from the light emitting diode of the first embodiment in that there is no upper DBR reflection layer and a current diffusion layer is provided instead.

6 is a schematic cross-sectional view of an example of the light emitting diode 300 according to the third embodiment.

As shown in FIG. 6, the light emitting diode 300 has a structure in which the current diffusion layer 40 is provided on the active layer 3.

In the present embodiment, as the material of the current diffusion layer 40, for example, AlGaAs or the like can be used.

The thickness of the current diffusion layer 40 is preferably 0.1 mu m or more and 10 mu m or less. If the thickness is less than 0.1 mu m, the current diffusion effect is insufficient. If the thickness exceeds 10 mu m, the effect on the epitaxial growth is too large for the effect.

As shown in Fig. 6, a light leakage preventing film 16 for preventing the light emitted from the active layer from leaking out of the element from the side surface of the mesa structure portion 7 may be provided. The light leakage preventing film 16 may be provided in another embodiment of the present invention.

As the material of the light leakage prevention film 16, a known reflection material can be used. The same AuBe / Au as the electrode layer 9 may be used.

[Method of Manufacturing Light Emitting Diode (First Embodiment)]

Next, a method of manufacturing the light emitting diode (resonator type light emitting diode) of the first embodiment will be described as an embodiment of the method of manufacturing the light emitting diode of the present invention.

7 is a cross-sectional schematic diagram showing a step of a method of manufacturing a light emitting diode. Fig. 8 is a schematic cross-sectional view showing one step after Fig. 7.

(Step of forming compound semiconductor layer)

First, the compound semiconductor layer 20 shown in FIG. 7 is prepared.

The compound semiconductor layer 20 is fabricated by sequentially laminating a lower DBR layer 2, an active layer 3, an upper DBR layer 4, and a contact layer 5 on a substrate 1.

A buffer layer (buffer) may be formed between the substrate 1 and the lower DBR layer 2. The buffer layer is formed to reduce the propagation of defects in the constituent layers of the substrate 1 and the active layer 3. Therefore, if the quality of the substrate or the epitaxial growth condition is selected, the buffer layer is not necessarily required. The material of the buffer layer is preferably the same as that of the substrate to be epitaxially grown.

In order to reduce the propagation of defects, a multi-layered film made of a material different from that of the substrate may be used for the buffer layer. The thickness of the buffer layer is preferably 0.1 mu m or more, and more preferably 0.2 mu m or more.

In the present embodiment, a known growth method such as molecular beam epitaxy (MBE) or reduced pressure metalorganic chemical vapor deposition (MOCVD) can be applied. Among them, it is most preferable to apply the MOCVD method having excellent mass productivity. Specifically, the substrate 1 used for epitaxial growth of the compound semiconductor layer is preferably subjected to a pretreatment such as a cleaning step or a heat treatment before growth to remove surface contamination or natural oxide film. Each of the layers constituting the compound semiconductor layer can be stacked by epitaxially growing the substrate 1 having a diameter of 50 to 150 mm in the MOCVD apparatus. As the MOCVD apparatus, a commercially available large apparatus such as a self-excited type or a high-speed rotating type can be applied.

As the material of the group III element, for example, trimethyl aluminum ((CH ₃ ) ₃ Al), trimethyl gallium ((CH ₃ ) ₃ Ga), and trimethyl aluminum Trimethyl indium ((CH ₃ ) ₃ In) can be used. As the doping material for Mg, for example, biscyclopentadienyl magnesium (bis- (C ₅ H ₅ ) ₂ Mg) may be used. As a doping material for Si, for example, disilane (Si ₂ H ₆ ) or the like can be used. Phosphine (PH ₃ ), arsine (AsH ₃ ) and the like can be used as a raw material of the group V element.

The carrier concentration, layer thickness, and temperature condition of each layer can be appropriately selected.

The compound semiconductor layer thus fabricated has a good surface state in which crystal defects are small even though the active layer 3 is provided. The compound semiconductor layer 20 may be subjected to surface processing such as polishing in accordance with the element structure.

(Step of forming back electrode)

Subsequently, as shown in Fig. 6, the back electrode 10 is formed on the back surface of the substrate 1. Then, as shown in Fig.

Specifically, when the substrate is an n-type substrate, for example, Au and AuGe are sequentially laminated by a vapor deposition method to form the back electrode 10 of the n-type Ohmic electrode.

(Step of forming mesa structure)

Next, a mesa structure portion (except for the protective film and the electrode film) in which the first wet etching is performed on the compound semiconductor layer and the sectional area in the horizontal direction is continuously reduced toward the top surface, Thereby forming the upper surface of the structural part.

Specifically, first, as shown in Fig. 8, a photoresist is deposited on the contact layer which is the uppermost layer of the compound semiconductor layer, and a resist pattern 23 having openings 23a in addition to the mesa structure portions is formed by photolithography do.

It is preferable that the size of the mesa structure portion to be formed in the resist pattern is larger than the normal face of the &quot; mesa structure portion &quot;

Subsequently, the first wet etching is performed using at least one etchant selected from the group consisting of, for example, a phosphoric acid / hydrogen peroxide mixture, an ammonia / hydrogen peroxide mixture, a bromomethane mixture, and potassium iodide / ammonia.

For example, a mixed solution of phosphoric acid / hydrogen peroxide aqueous solution of H ₃ PO ₄ : H ₂ O ₂ : H ₂ O = 1 to 3: 4 to 6: 8 to 10 is used and the wet etching time is 30 to 60 seconds, At least a part of the contact layer, the upper DBR layer and the active layer, or at least a part of the contact layer, the upper DBR layer, the active layer and the lower DBR layer are removed.

Thereafter, the resist is removed.

When the mesa structure is viewed from the plane, the shape is determined by the shape of the opening 23a of the resist pattern 23. An opening 23a having a shape corresponding to the shape as viewed in a desired plane is formed in the resist pattern 23.

The depth of the etching, that is, to which layer of the compound semiconductor layer is to be etched away, is determined by the type of etchant and the etching time.

In FIG. 9, an etchant of H ₃ PO ₄ : H ₂ O ₂ : H ₂ O = 2: 5: 9 (100: 250: 450), 56% (H ₂ O) And the depth and width of the compound semiconductor layer described in Example 1 to be described later with respect to the etching time when wet etching is performed. Table 1 shows the conditions and results in numerical values.

From FIG. 9 and Table 1, it is found that the etching depth (corresponding to "h" in FIG. 1) is almost proportional to the etching time (sec), but the etching width increases as the etching time becomes longer. That is, as shown in FIG. 3, the increase in the horizontal cross-sectional area (or the width or diameter) of the mesa structure portion is increased as it gets deeper (downward in the drawing).

This etching shape is different from the etching shape by dry etching. Therefore, from the shape of the inclined slope of the mesa structure portion, it can be determined whether the mesa structure portion is formed by dry etching or wet etching.

By the first wet etching, the portions of the wafer substrate excluding the mesa structure portions (the streets and the support structure portions) have the same height.

(Step of forming the inclined portion of the support structure)

Subsequently, a second wet etching is performed along the cleavage cutting line (dotted line 22 in Fig. 2) to form the inclined portion 6ba of the side surface 6a of the supporting structure 6. [

More specifically, first, a photoresist is deposited on the entire surface of the wafer substrate, and photolithography is performed to form a photoresist film having a predetermined distance d (see FIG. 2) from the periphery of the upper surface 6a of the support structure 6 and the street 21 A resist pattern having openings is formed.

Subsequently, the second wet etching is performed using at least one kind of etchant selected from the group consisting of a phosphoric acid / hydrogen peroxide mixture, an ammonia / hydrogen peroxide mixture, and a bromomethane mixture.

For example, a mixed solution of phosphoric acid / hydrogen peroxide aqueous solution of H ₃ PO ₄ : H ₂ O ₂ : H ₂ O = 1 to 3: 4 to 6: 8 to 10 is used and the wet etching time is 30 to 60 seconds, Thereby forming the inclined portion 6ba of the side surface 6a of the support structure 6. [

Thereafter, the resist is removed.

The inclination angle, length, and depth of the inclined portion 6ba are determined by the kind of the etchant and the etching time.

(Process of forming protective film)

Subsequently, at least a part of the upper surface 6a and at least the inclined portion 6ba, the inclined side surface 7a and the peripheral edge region 7ba of the top surface 7b of the side surface 6b are covered A protective film 8 having an energizing window 8b exposing a part of the surface of the compound semiconductor layer (contact layer 5) is formed inside the peripheral region 7ba.

More specifically, first, the material of the protective film 8 is formed on the entire surface. Specifically, for example, SiO ₂ is formed on the entire surface by sputtering.

Subsequently, a photoresist is deposited on the entire surface, and the upper surface 6a, the inclined portion 6ba, the inclined side surface 7a, the portion other than the peripheral region 7ba of the top surface 7b, And a portion corresponding to the energizing window 8b for exposing a part of the surface of the compound semiconductor layer as an opening is formed.

Subsequently, the protective film 8 is formed by removing the material of the protective film corresponding to the opening by, for example, wet etching using buffered hydrofluoric acid.

Fig. 10 shows a plan view of the protective film 8 in the vicinity of the power window 8b. and an energizing window 8b without a protective film 8 between d _in and d _out .

Thereafter, the resist is removed.

(Step of forming surface electrode layer and light leakage preventing layer)

Then, at least a part of the surface of the compound semiconductor layer (contact layer 5) exposed from the current-carrying window 8b and at least a part of the upper surface thereof are covered with the light injection hole 9b on the top surface of the mesa structure portion 7 A surface electrode layer (electrode layer) 9 and a light leakage preventing layer 24 which are continuous films formed on the protective film 8 are formed. Specifically, a photoresist is deposited on the entire surface, and an electrode film (not shown) including a portion corresponding to the light emitting hole 9b and a cut portion (street) between a plurality of light emitting diodes on the wafer substrate is formed by photolithography Thereby forming a resist pattern having openings other than the unnecessary portions. Subsequently, an electrode layer material (a light leakage preventing film is also formed of an electrode layer material) is deposited. When the electrode layer material is not sufficiently deposited on the inclined sides of the mesa structure and the inclined portions of the support structure by the deposition alone, the deposition metal is mixed to the inclined side of the mesa structure and the inclined part of the support structure to deposit the electrode layer material. The deposition is further performed using a plasma-type deposition apparatus which is liable to be generated.

Thereafter, the resist is removed.

The shape of the light emitting orifice 9b is determined by the shape of the opening of the resist pattern (not shown). And a resist pattern is formed so that the opening shape corresponds to the shape of the desired light emitting orifice 9b.

(Discretization process)

Subsequently, the light emitting diodes on the wafer substrate were disassembled to produce light emitting diodes (chips).

Specifically, for example, a street portion is cut by a dicing saw or a laser, and cut into individual light emitting diodes on the wafer substrate to be separated.

[Manufacturing method of light emitting diode (second embodiment)]

The light emitting diode (second embodiment) of the present invention differs from the light emitting diode (first embodiment) in the arrangement of the protective film and the electrode, and its manufacturing method is similar to that of the light emitting diode (first embodiment) .

[Manufacturing method of light emitting diode (third embodiment)]

The method of manufacturing the light emitting diode (third embodiment) of the present invention differs from the method of manufacturing the light emitting diode (first embodiment) in that, in the step of forming the compound semiconductor layer, the lower DBR layer And the current diffusion layer 40 is laminated on the active layer 3 after the active layer 3 is laminated on the active layer 3. The other steps can be carried out in the same manner as the method for manufacturing the light emitting diode (first embodiment).

The etchant used for the first wet etching and the second wet etching of the present invention is not limited, but an ammonia-based etchant (for example, ammonia / aqueous hydrogen peroxide solution) is preferably used for an As-based compound semiconductor material such as AlGaAs And an iodine type etchant (for example, potassium iodide / ammonia) is suitable for the P-based compound semiconductor material such as AlGaInP, and the phosphoric acid / hydrogen peroxide mixture is suitable for the AlGaAs system and the bromo methanol mixture is suitable for the P system .

Therefore, in each wet etching, a plurality of etchants can be used.

For example, when the compound semiconductor layer is composed of a current diffusion layer made of AlGaAs, a cladding layer made of AlGaInP, a light emitting layer made of AlGaAs, and a clad layer made of AlGaInP, the current diffusion layer and the light emitting layer of the As- An etchant is used for the P-type clad layer, and an iodine-based etchant can be used for the P-type clad layer. In this case, since the layer under the etching layer functions as an etching stop layer, it is not necessary to strictly control the etching time.

For example, in a structure formed only of an As system, a mixed solution of phosphoric acid and an As / P system may be used, and an ammonia mixture may be used in an As system structure and an iodine mixture may be used in a P system structure.

When an etchant mixed with 500 cc of iodine (I), 100 g of potassium iodide (KI), 2000 cc of pure water (H ₂ O) and 90 cc of aqueous ammonia (NH ₄ OH) was used, the etching rate of the layer made of AlGaInP was 0.72 μm / min.

Example

Hereinafter, the light emitting diode of the present invention and the manufacturing method thereof will be described in more detail by way of examples, but the present invention is not limited to these examples. In this embodiment, the resonator type light emitting diode chip shown in Fig. 1 was fabricated, and a light emitting diode lamp in which the light emitting diode chip was mounted on the substrate was manufactured for evaluation of characteristics.

(Example)

In the light emitting diode of the embodiment, first, compound semiconductor layers were sequentially laminated on a GaAs substrate made of n-type GaAs single crystal doped with Si to produce an epitaxial wafer. The GaAs substrate had a (100) plane as the growth surface and a carrier concentration of 2 × 10 ¹⁸ cm ^-3 .

Further, the layer thickness of the GaAs substrate was about 250 mu m. It is a compound semiconductor layer, a buffer layer of n-type formed of a GaAs doped with Si, Al _{0 .9} doped with Si _{0 .1} Ga As and Al _{0 .1} Ga _{0 .9} As 40 pair of the n-type repeating structure of the a doped lower DBR reflection _{layer, Si Al 0 .4 Ga 0 .6} as lower clad layer of n-type comprising a lower guide layer made of _{Al 0 .25 Ga 0 .75 as,} GaAs / Al 0 .15 Ga 0. ₈₅ As, an upper guide layer made of Al _{0 .25} Ga _{0 .75} As, a p-type upper cladding layer made of Al _{0 .4} Ga _{0 .6} As doped with C, a lower cladding layer made of Al the doped a Al _0.9 Ga _0.1 as and Al Ga _{0 .1} upper DBR reflection layer of _{0 .9} as 5 pair of the p-type repeating structure of the, C-doped contact layer made of a p-type Al _{0 .1} Ga _{0 .9} as to be.

In this embodiment, a compound semiconductor layer is epitaxially grown on a GaAs substrate of 50 mm in diameter and 250 占 퐉 in thickness using a reduced-pressure metal-organic chemical vapor deposition apparatus (MOCVD apparatus) to form an epitaxial wafer. Trimethylaluminum ((CH ₃ ) ₃ Al), trimethylgallium ((CH ₃ ) ₃ Ga) and trimethylindium ((CH ₃ ) ₃ In) are used as raw materials for group III constituent elements when growing the epitaxially grown layer. Used. Tetrabromomethane (CBr ₄ ) was used as a raw material for doping C. Disilane (Si ₂ H ₆ ) was used as a raw material for doping Si. Phosphine (PH ₃ ) and arsine (AsH ₃ ) were used as raw materials for the group V element. The growth temperature of each layer was 700 占 폚.

The buffer layer made of GaAs has a carrier concentration of about 2 × 10 ¹⁸ cm ^-3 and a layer thickness of about 0.5 μm. A lower DBR reflection layer is a carrier concentration of about 1 × 10 ¹⁸ ㎝ ^-3, about the Al _{0 .9} Ga _{0 .1} As, and a carrier concentration of about 1 × 10 ¹⁸ ㎝ ^-3, layer thickness of a layer thickness of about 54nm 40 pieces of Al _0.1 Ga _0.9 As alternately laminated were formed. The lower clad layer had a carrier concentration of about 1 x 10 ¹⁸ cm ^-3 and a layer thickness of about 54 nm. The lower guide layer is undoped and has a layer thickness of about 50 nm. The well layer is undoped, made of GaAs having a layer thickness of about 7 nm, and the barrier layer is made of Al _{0 .15} Ga _{0 .85} As, which is undoped and has a layer thickness of about 7 nm. Further, three pairs of the well layer and the barrier layer were alternately laminated. The upper guide layer is undoped and has a layer thickness of about 50 nm. The upper clad layer has a carrier concentration of about 1 x 10 ¹⁸ cm ^-3 and a layer thickness of 54 nm. The upper DBR reflection layer is a carrier concentration of about 1 × 10 ¹⁸ ㎝ ^-3, the Al _{0 .9} layer thickness of about 54nm _{0 .1} Ga As, and a carrier concentration of about 1 × 10 ¹⁸ ㎝ ^-3, layer thickness Of Al _{0 .1} Ga _{0 .9} As having a thickness of about 51 nm were alternately stacked.

The contact layer made of Al _{0 .1} Ga _{0 .9} As has a carrier concentration of about 3 × 10 ¹⁸ cm ^-3 and a layer thickness of about 250 nm.

Subsequently, AuGe and Ni alloy were formed on the back surface of the substrate by a vacuum evaporation method so as to have a thickness of 0.5 mu m, Pt of 0.2 mu m, and Au of 1 mu m on the back surface of the substrate, thereby forming an n type ohmic electrode.

Subsequently, a patterned resist (AZ5200NJ (manufactured by Clariant)) was used to form a mesa structure, and a phosphoric acid / hydrogen peroxide aqueous solution of H ₃ PO ₄ : H ₂ O ₂ : H ₂ O = 2: 5: 9 And a first wet etching was performed for 45 seconds to form a mesa structure and an upper surface. This wet etching removes all layers of the contact layer, the upper DBR reflecting layer, and the active layer to form a rectangular mesa having a size of 190 mu m x 190 mu m, a height h of 4 mu m, and a width w of 3 mu m (Excluding the protective film and the electrode film) were formed.

Subsequently, to form the inclined portion of the supporting structure, a resist (AZ5200NJ (manufactured by Clariant Co., Ltd.), which is patterned so as to have an opening in a range of a predetermined distance d from the outer periphery of the upper surface 6a of the supporting structure 6, Ltd.) was used and the second wet etching was performed for 45 seconds using a phosphoric acid / hydrogen peroxide aqueous solution of H ₃ PO ₄ : H ₂ O ₂ : H ₂ O = 2: 5: 9. Thus, an inclined portion having a width of 4 mu m and a depth of 3 mu m was formed.

Then, to form a protective film, a protective film made of SiO ₂ was formed to a thickness of about 0.5 탆.

Thereafter, after patterning with a resist (AZ5200NJ (manufactured by Clariant)), an opening of a concentric circle (outer diameter d _out : 166 mu m, inner diameter d _in : 154 mu m) And an opening in the range of a predetermined distance d from the outer periphery of the upper surface 6a of the street portion and the supporting structure portion 6 were formed.

Subsequently, after patterning with a resist (AZ5200NJ (manufactured by Clariant)) to form the light leakage preventing film 24 of the inclined portion of the surface electrode (film) and the supporting structure portion, 1.2 占 퐉 of Au and 0.15 占 퐉 of AuBe (P-type ohmic electrode) formed by 350 占 퐉 long side and 250 占 퐉 long side having light emitting holes 9b having a circular shape (diameter: 150 占 퐉) as viewed in a plan view by lift-off, Thereby forming a light leakage preventing film 24 at an inclined portion of the structural portion.

Thereafter, heat treatment was performed at 450 占 폚 for 10 minutes to alloy them to form p-type and n-type ohmic electrodes of low resistance.

After patterning with a resist (AZ5200NJ (manufactured by Clariant)) to form a light leakage preventing film 16 on the side surface of the mesa structure portion, Ti was deposited to 0.5 mu m and Au was deposited to 0.17 mu m in this order, The light leakage preventing film 16 was formed.

Then, a dicing saw was used to cut from the side of the compound semiconductor layer at the street portion, and chipped. The crushed layer and dirt by dicing were removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide to prepare a light emitting diode of the example.

The light emitting diode chip of the example fabricated as described above was assembled with 100 light emitting diode lamps mounted on a mount substrate. The light emitting diode lamp was manufactured by mounting a mount by a die bonder, wire-bonding the p-type ohmic electrode and the p-electrode terminal with a gold wire, and then sealing with a general epoxy resin.

In this light emitting diode (light emitting diode lamp), when current was passed between the n-type and p-type ohmic electrodes, infrared light having a peak wavelength of 850 nm was emitted. The forward voltage (V _F ) when passing a current of 20 milliampere (mA) in the forward direction was 1.6 V. The emission output when the forward current was 20 mA was 1.5 mW. The response speed (rise time: Tr) was 12.1 nsec.

11 shows a state in which the second wet etching is not performed and except for the point that does not have the inclined portion 6ba (and thus does not have the protective film 8f and the light leakage preventing film 24 on the inclined portion 6ba) 5 is a graph showing a measurement result of an optical spectrum immediately above a light emitting diode having the same configuration as the example (see the schematic diagram on the right side of the graph). The vertical axis indicates the intensity of light, and the horizontal axis indicates wavelength.

As shown in Fig. 11, in this light emitting diode, the linewidth of the light emission spectrum was narrow (monochromaticity was high) and the half width (HWHM) was 6.3 nm.

Although this light emitting diode is not the light emitting diode according to the present invention, the high monochromaticity of the luminescent light shown in Fig. 11 is considered to be effective regardless of the presence or absence of the inclined portion 6ba. Therefore, It is considered to have the same high monochromaticity.

Fig. 12 is a graph showing the measurement results of the directivity of emitted light (see the schematic diagram on the right side of the graph) for the light emitting diode showing the characteristics in Fig. The circumference connected from "-1" to "1" on the abscissa in the graph indicates 13000 as the intensity of light (Int.). Thus, for example, when the intensity of light in one direction is 6500, the graph comes on the circumference connected from "-0.5" to "0.5" on the horizontal axis in that direction. For example, in the light emitting diode of the embodiment, there is a graph on the circumference (not shown) connected from approximately "-0.9" to "0.9" in the direction of ± 10 ° from immediately above (90 °) The strength was found to be about 90% of 13000.

As shown in Fig. 12, the light emitting diode had high intensity (about 70% or more of 13000) in the range of about 15 占 from directly above the light emitting hole and exhibited high directivity.

Although this light emitting diode is not the light emitting diode according to the present invention, the directivity of the emitted light shown in Fig. 12 is considered to be effective regardless of the presence or absence of the inclined portion 6ba. Therefore, It is considered to have the same high directivity.

Any one of the 100 light emitting diode lamps produced had the same degree of characteristics and was caused by leakage (short circuit) when the protective film was a discontinuous film or defective energization when the electrode metal film was a discontinuous film There was no bad thought. Further, it was confirmed that the side surface of the light emitting diode was covered with the protective film, and the deterioration of the side surface due to contact with moisture in the air or the atmosphere was prevented from the characteristics of the light emitting diode lamp.

(Comparative Example)

Shows an example of a light emitting diode with a wavelength of 850 nm which is formed by thick film growth by a liquid phase epitaxial method and a substrate is removed.

An AlGaAs layer was grown on a GaAs substrate using a slide boat type growth apparatus.

A p-type GaAs substrate was set in a substrate receiving groove of a slide boat type growth apparatus, and Ga metal, a GaAs polycrystal, a metal Al and a dopant were placed in a crucible prepared for growth of each layer.

The growing layer has a four-layer structure of a transparent thick film layer (first p-type layer), a lower clad layer (p-type clad layer), an active layer, and an upper clad layer (n-type clad layer).

Slide boat type growth apparatuses in which these raw materials were set were set in a quartz reaction tube and heated to 950 占 폚 in a hydrogen stream to dissolve the raw materials. The atmosphere temperature was lowered to 910 占 폚, Melts), and then the temperature is lowered at a rate of 0.5 ° C / min. After reaching the predetermined temperature, the slider is pressed again to sequentially contact the respective raw material solutions and then heated at high temperature. Finally, , The temperature of the atmosphere was lowered to 703 DEG C to grow the n-clad layer, and then the slurry was pressed to separate the raw material solution and the wafer, thereby completing the epitaxial growth.

The structure of the obtained epitaxial layer is such that the first p-type layer has an Al composition X1 = 0.3 to 0.4, a layer thickness of 64 m, a carrier concentration of 3 x 10 ¹⁷ cm- ³ , and a p- , 79㎛ thickness, carrier concentration of 5 × 10 ¹⁷ ㎝ ^-3, p-type active layer, in the proportion of the light-emitting wavelength of 760nm, the thickness 1㎛ layer, carrier density 1 × 10 ¹⁸ ㎝ ^-3, n-type cladding layer, It was Al composition X4 = 0.4 to 0.5, a layer thickness 25㎛, carrier concentration of 5 × 10 ¹⁷ ㎝ ^-3.

After the epitaxial growth was completed, the epitaxial substrate was taken out to protect the surface of the n-type GaAlAs cladding layer, and the p-type GaAs substrate was selectively removed with an ammonia-hydrogen peroxide system etchant. Thereafter, a gold electrode was formed on both surfaces of the epitaxial wafer, and a surface electrode having a wire bonding pad having a diameter of 100 mu m arranged at the center was formed using an electrode mask having a long side of 350 mu m. On the back electrode, ohmic electrodes having a diameter of 20 mu m were formed at intervals of 80 mu m. Thereafter, the LED was separated and etched by dicing to produce a rectangular LED having a length of 350 mu m on one side so that the n-type AlGaAs layer was on the surface side.

When a current was passed between the n-type and p-type Ohmic electrodes of the light emitting diode of the comparative example, infrared light having a peak wavelength of 850 nm was emitted. The forward voltage (V _F ) when the current of 20 milliampere (mA) was passed in the forward direction was 1.9 V. The emission output when the forward current was 20 mA was 5.0 mW. The response speed Tr is 15.6 nsec, which is slower than the embodiment of the present invention.

As shown in Fig. 10, in the light emitting diode of the comparative example, the linewidth of the luminescence spectrum was wide and the half width (HWHM) was 42 nm.

As shown in Fig. 11, in the light emitting diode of the comparative example, light having a hemispheric shape centered on the light emitting diode was emitted at a light intensity of about 20% or less of 13000, and the directivity was considerably lower than that in Examples.

1: substrate
2: Lower DBR layer (reflective layer)
3:
4: upper DBR layer
5: contact layer
6: Support structure
6a: upper surface
6b: Side
6ba:
7: Mesa type structure
7a: incline side
7b: Height
7ba: peripheral region
8, 28: Shield
8b, 28b: energizing window
9, 29: electrode film
9b: light injection hole
11: Lower clad layer
12: Lower guide layer
13:
14: upper guide layer
15: upper cladding layer
16: Light leakage prevention film
20: compound semiconductor layer
21: Street
23: Resist pattern
24: Light leakage preventing film
40: current diffusion layer
100, 200: light emitting diodes

Claims (17)

A light emitting diode comprising a compound semiconductor layer including a reflective layer and an active layer on a substrate,
A support structure having an upper surface and a side surface; and a mesa structure disposed on the support structure and having an inclined side surface and a steep surface,
Wherein the reflective layer is a DBR reflective layer,
A back electrode is formed on a lower surface side of the substrate,
Wherein the support structure portion includes at least a part of the reflective layer and includes an inclined portion whose side is formed by wet etching and extends from the upper surface to a position exceeding at least the reflective layer from the upper surface, Wherein a cross sectional area in the horizontal direction is continuously reduced toward the upper surface,
Wherein the mezzanine structure portion includes at least a part of the active layer, the inclined side surface is formed by wet etching, and the cross sectional area in the horizontal direction is formed continuously smaller toward the top surface,
Wherein the support structure portion and the mesa structure portion are each covered in order by a protective film and an electrode layer,
Wherein the protective film includes at least a portion of the upper surface, at least an inclined portion of the side surface, the inclined side surface and at least a peripheral region of the top surface, And a power window,
Wherein the electrode layer directly contacts a surface of the compound semiconductor layer exposed from the power window and at least partially covers a protective film formed on the upper surface and has a light emitting hole on the top surface of the mesa structure portion, Is a continuous film formed so as to extend from the top surface to the top surface of the supporting structure portion. delete The light emitting diode according to claim 1, further comprising an upper DBR reflective layer on an opposite side of the active layer of the substrate. 4. The apparatus according to any one of claims 1 to 3, wherein the inclined portion comprises at least two inclined portions, each of the cross-sectional areas in the horizontal direction including the inclined portions is continuously small toward the upper surface and includes inclined portions close to the upper surface And the cross sectional area in the horizontal direction is smaller. The light emitting diode according to any one of claims 1 to 4, further comprising a light leakage preventing film on or above the electrode layer or the protective film. The light emitting diode according to claim 1 or 3, wherein the compound semiconductor layer has a contact layer contacting the electrode layer. delete The light emitting diode according to claim 1 or 3, wherein the mesa structure is rectangular in plan view. delete The light emitting diode according to claim 1 or 3, wherein the mesa structure has a height of 3 to 7 占 퐉 and a width of the oblique side viewed from a plane is 0.5 to 7 占 퐉. The light emitting diode according to claim 1 or 3, wherein the light emitting hole is circular or elliptical in plan view. The light emitting diode according to claim 11, wherein a diameter of the light emitting hole is 50 to 150 占 퐉. The light emitting diode according to claim 1 or 3, further comprising a bonding wire on a portion of the electrode layer above the upper surface. The light emitting diode according to claim 1 or 3, wherein the light emitting layer included in the active layer is composed of multiple quantum wells. The method of claim 1 or claim 3, wherein the light-emitting layer _{((Al X1 Ga 1-X1} ) Y1 In 1-Y1 P (0≤X1≤1, 0 <Y1≤1), (Al X2 Ga contained in the active layer a light emitting diode which comprises any one of a _{1-X2) as (0≤X2≤1)} , (in X3 Ga 1-X3) as (0≤X3≤1)). A method of manufacturing a light emitting diode comprising a support structure having an upper surface and a side surface, and a mesa structure having an inclined side surface and a top surface,
A step of forming a compound semiconductor layer including a reflective layer and an active layer which are DBR reflective layers on a substrate,
A step of forming a back electrode on a substrate,
A mesa structure section in which the first wet etching is performed on the compound semiconductor layer and a cross sectional area in the horizontal direction is continuously reduced toward the top surface, and a step of forming an upper surface of a support structure section disposed around the mesa structure section,
Performing a second wet etching along the cleavage line to form a sloped portion on the side surface of the support structure;
A step of forming a protective film on the support structure and the mesa structure so as to have the inclined portion and the energizing window covering at least a part of the upper surface and exposing a part of the surface of the compound semiconductor layer on the top surface of the mesa structure, and,
Wherein the mesa structure is formed on the top surface of the mesa structure so as to directly contact the surface of the compound semiconductor layer exposed from the power window and at least part of the protective film formed on the top surface, And forming an electrode layer which is a continuous film extending to the upper surface. The method according to claim 16, wherein the first and second wet etching are performed using at least one selected from the group consisting of a phosphoric acid / hydrogen peroxide mixture, an ammonia / hydrogen peroxide mixture, a bromomethane mixture, and potassium iodide / ammonia Wherein the light emitting diode has a light emitting diode.

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