JP5486759B2 - Manufacturing method of semiconductor light emitting device - Google Patents

Description

  The present invention relates to a highly efficient semiconductor light emitting device with improved light extraction efficiency.

  A semiconductor light emitting device such as a light emitting diode is configured by stacking n-type and p-type semiconductor layers on a substrate. The semiconductor light emitting element is used in a state of being mounted on a submount or the like for fixing to the light emitting device and conduction with an external power source. As a mounting form, there are face-up mounting in which the back surface side of the substrate is opposed to the submount and flip chip mounting in which the semiconductor layer side is opposed to the submount. Light emitted from the semiconductor light emitting element is extracted from the semiconductor layer side to the outside in face-up mounting, and is extracted through the substrate in flip chip mounting.

Flip chip mounting has been put to practical use as a method for mounting a nitride semiconductor light emitting device laminated on a sapphire substrate that transmits visible light. However, there is a step in the semiconductor stacked body that is the mounting surface, and advanced technology is required to mount the light emitting element flatly. In addition, since the n-side electrode is adjacent to the p-type semiconductor layer, there is a high possibility of short-circuiting due to protrusion of solder bumps, eutectic layers, etc., which requires protection by an insulating film and requires accurate mounting accuracy. Has been.
On the other hand, face-up mounting has the advantage of being easier to mount than flip chip mounting because the mounting surface is the flat bottom surface of the substrate and conduction is achieved by wire bonding.

In this face-up mounting, the conduction method with the external electrode differs depending on the type of substrate.
In a semiconductor light emitting device including a conductive substrate, an N-contact on the lower surface of the substrate and a P-contact (pad electrode) on the upper surface of the semiconductor layer are connected to external electrodes, respectively (for example, in Patent Document 1). FIG. 3C).
In a semiconductor light emitting device provided with an insulating substrate, a p-side pad electrode and an n-side pad electrode are formed on the semiconductor layer side to conduct with an external electrode. For example, in a light emitting device in which a p-type semiconductor layer is stacked on an n-type semiconductor layer, the p-type semiconductor layer and the active layer are partially cut away to expose the n-type semiconductor layer, and the p-type semiconductor layer is formed on the upper surface of the p-type semiconductor layer. A p-side pad electrode and an n-side pad electrode are formed on the exposed surface of the n-type semiconductor layer (for example, Patent Document 2).
JP 2003-69086 A JP-A-8-250769

  Whether the semiconductor light emitting element of the conductive substrate as in Patent Document 1 or the semiconductor light emitting element of the insulating substrate as in Patent Document 2, the conduction between the pad electrode formed on the semiconductor layer side and the external electrode is Wire bonding using a gold wire or the like is used. In order to appropriately perform wire bonding on the semiconductor side, a pad electrode formed on the semiconductor layer side is a metal thick film (for example, Ti / thickness) having an appropriate area (for example, 70 μm or more in diameter) and an appropriate thickness (for example, 3000 mm or more). Au laminate). Since a thick metal film of 3000 mm or more does not transmit visible light, a dark portion in the shape of a pad electrode appeared in the light emitting surface when the semiconductor light emitting element was energized.

  The size of the pad electrode needs to be a predetermined size (for example, a diameter of about 70 μm or more) depending on the accuracy of wire bonding and the thickness of the gold wire. Therefore, when the area of the semiconductor light emitting element is reduced, the ratio of the light shielding area to the light emitting area is increased, and the light extraction efficiency from the semiconductor layer side may be extremely low.

  In particular, a nitride semiconductor light emitting element has a property that the film resistance of the p-type semiconductor layer is high, and it is difficult to spread the current inside the p-type semiconductor layer. Therefore, by forming a translucent electrode on the surface of the p-type semiconductor layer and positioning it between the p-side pad electrode and the p-type semiconductor layer, a current flowing from the p-side pad electrode is widely spread to the p-type semiconductor layer. It helps to spread. However, if the translucent electrode is formed in a thick film, sufficient translucency cannot be ensured. Therefore, the film thickness is made thin at the expense of some reduction in resistance. For this reason, the current diffusion of the translucent electrode is not sufficient, the ratio of the current flowing directly below the p-side pad electrode is increased, and the light directly below the p-side pad electrode emits the strongest light. However, since the p-side pad electrode blocks the strong light, the light extraction efficiency has been greatly reduced. Further, a part of the light shielded by the p-side pad electrode is reflected by the lower surface of the p-side pad electrode, propagates in the light emitting element in the lateral direction, and is extracted from the side surface of the light emitting element. No metal material suitable for forming the film has a high reflectivity, which causes light loss.

Even in the case of a semiconductor light emitting device in which a p-type semiconductor layer and an n-type semiconductor layer are sequentially laminated on a substrate, light shielding by an n-side pad electrode has been a problem.
An example is a so-called bonded light emitting diode in which a conductive substrate is bonded to the p-type nitride semiconductor layer side. The n-side pad electrode is formed on the upper surface of the semiconductor stacked body, and current from the p-type semiconductor layer flows into the n-side pad electrode. Although the sheet resistance of the n-type nitride semiconductor is considerably lower than that of the p-type nitride semiconductor layer, there is still a tendency that the portion directly below the n-side pad electrode shines strongly. For this reason, the n-side pad electrode is a cause of reducing the light extraction efficiency by shielding the strong light. In addition, if a light-transmitting electrode is formed between the n-type semiconductor layer and the n-side pad electrode to diffuse the current, the tendency of strong light emission immediately below the pad electrode can be alleviated. There was a problem and the light extraction efficiency could not be increased.

  Further, as in Patent Document 2, in a semiconductor light emitting device in which an n-type nitride semiconductor layer and a p-type nitride semiconductor layer are sequentially stacked on an insulating substrate, the n-side pad electrode is formed in a cut portion cut out to the active layer. Therefore, no light emission occurs immediately below the n-side pad electrode. However, it is known that light emitted in the semiconductor propagates laterally in the semiconductor layer and reaches the lower surface side of the pad electrode. These propagating lights are not as strong as those directly above the active layer, but have sufficient luminance, but are shielded by the n-side pad electrode and cannot be taken out from the cut portion. A part of the light shielded by the n-side pad electrode is reflected by the lower surface of the n-side pad electrode, and further propagates laterally through the semiconductor layer, so that it is finally extracted from the side surface of the light emitting element. When the propagation distance is long, there is a problem that the light intensity is attenuated due to light loss due to the low reflectance of the pad electrode or attenuation inside the semiconductor. Therefore, from the viewpoint of light extraction efficiency, it is preferable to extract the propagation light to the outside while the propagation distance in the lateral direction is short.

In general face-up mounting, a metal wire is stretched in an arc by wire bonding, so that the metal wire partially protrudes from the surface of the semiconductor light emitting element, and the light emitting device using the semiconductor light emitting element is thin. It was a cause that hindered downsizing and downsizing. Further, since the stretched metal wire such as a gold wire crosses between the light emitting surface of the light emitting element and the observation direction, it also hinders light extraction.
And since the metal wire used for wire bonding is very thin, when a stress is applied, it is easy to break, causing a defect in the manufacturing process.

  In addition, in a light-emitting device in which a semiconductor light-emitting element and a phosphor are combined, there is a method of attaching a phosphor after face-up mounting of the semiconductor light-emitting element. In this method, the phosphor adheres to a metal wire and becomes a metal. There is a problem that the wire is easily cut and a problem that the light emitted from the semiconductor light emitting element leaks along the phosphor attached to the wire to cause abnormal light emission.

  Accordingly, an object of the present invention is to provide a semiconductor light emitting device that is suitable for face-up mounting, improves light extraction efficiency, and further reduces luminance unevenness. Another object of the present invention is to provide a semiconductor light emitting device that can reduce the thickness during mounting face up and can solve various problems caused by wire bonding.

The present invention includes a laminate in which a substrate, an n-type nitride semiconductor layer, and a p-type nitride semiconductor layer are sequentially laminated from the lower surface side to the upper surface side,
A p-side translucent electrode provided on the upper surface of the p-type nitride semiconductor layer;
A translucent current spreading portion provided on the upper surface of the p-side translucent electrode;
The current diffusion portion and are electrically connected to the p Gawashirube conductive portion extending to the lower side from the upper surface side of the laminate, a manufacturing method of the semiconductor light emitting element Ru with a
The n-type nitride semiconductor layer and the p-type nitride semiconductor layer are sequentially stacked on the substrate to form the stacked body, and then reach the middle of the thickness of the substrate from the p-type nitride semiconductor layer side. A hole is formed, the inner surface of the hole to the edge of the opening is covered with an insulating film, and is made of a conductive oxide for constituting the p-side translucent electrode and the p-side conductive portion. A translucent conductive film is formed so as to cover the insulating film and extend to the upper surface of the p-type nitride semiconductor layer;
Then, after polishing the lower surface side of the substrate to penetrate the hole and opening the lower end of the insulating film and the translucent conductive film, individual semiconductor light emission along the line passing through the through hole by splitting the element, the p and Gawashirubeden unit, before Symbol semiconductor side portions of the light-emitting element or located at a corner from the lower surface of the substrate the p-type light-transmissive electrode to extend to the p-side groove of therein, a method for manufacturing a semiconductor light emitting device characterized by the lower end of that is formed by an insulating film that matches the bottom surface of the substrate.

The semiconductor light emitting device, the electrode of the p-type nitride semiconductor layer (p-side translucent electrode) is translucent and can be blocked the light generated in the active layer to the electrode efficiently extract without . In particular, since light emitted directly under the pad electrode that has been completely shielded from light by the pad electrode can be extracted efficiently, the effect of improving the light extraction efficiency is remarkable.
In the present invention, the p-side translucent electrode formed on the "p-type nitride semiconductor layer top surface of the" includes a p-type nitride semiconductor and p-side-type conductivity is formed on the upper surface of the layer a semiconductor it is meant to be a p-side light transmitting electrode which is conductive. That, p-side light transmitting electrode, in addition to the form that is formed is conductive in direct contact with the p-side conductive type semiconductor, and a p-side conductive semiconductor through the other conductive layer or another semiconductor layer It includes a form that is indirectly conducted. These intervening conductive layers and semiconductor layers can be formed from various materials as long as light can be taken out and the function of the semiconductor light emitting element is not impaired.

The semiconductor light emitting device, the a laminate the n-type nitride semiconductor layer n-side light-transmitting electrode provided on the partially exposed on the upper surface of the lower surface of the substrate from the n-side light transmitting electrode and n-side conductive portion of the extending been translucent to, may further comprise a.

Such a semiconductor light emitting device does not emit light because there is no active layer in the region where the n-type nitride semiconductor layer is exposed, but light emitted from other regions is reflected laterally while reflecting the inside of the semiconductor stacked body. Propagating. A portion of this propagated light, it is possible to take out through the n-side light transmitting electrode, there is an effect of relaxing the unevenness in luminance distribution conventional pad electrode had occurred to block the light. Further, in this semiconductor light emitting device, by providing the second light transmissive electrode instead of the pad electrode, the laterally propagated light can be taken out from the exposed portion of the n-side conductive semiconductor layer within a short propagation distance. Therefore, an increase in attenuation due to an increase in propagation distance can be suppressed, and the light extraction efficiency can be improved.

  In addition, although this semiconductor light emitting device is for face-up mounting, it can be mounted by a conductive portion exposed on the lower surface side of the substrate without using wire bonding. That is, this semiconductor light emitting device has a feature that the light extraction efficiency can be remarkably improved because it can be face-up mounted without a pad electrode or a metal wire for shielding light emission. Furthermore, since the problem of protrusion of the metal wire does not occur, the mounting height of the semiconductor light emitting element can be suppressed. And since the defect resulting from wire bondings, such as cutting and peeling of a metal wire, does not occur, the defect rate can be reduced.

  A semiconductor light-emitting element that can be mounted without wire bonding is suitable for use in a light-emitting device that combines a semiconductor light-emitting element and a phosphor. Since this semiconductor light emitting device does not require wire bonding, the problem that the phosphor adheres to the metal wire does not occur, and defective wire cutting or abnormal light emission along the wire does not occur. The semiconductor light emitting device of the present invention is advantageous in that the phosphor can be deposited on the surface of the light emitting diode with a uniform thickness.

  As described above, the semiconductor light emitting device according to the present invention is suitable for face-up mounting, can improve the light extraction efficiency, and further reduce the luminance unevenness. The semiconductor light emitting device according to the present invention is a semiconductor light emitting device capable of reducing the thickness during face-up mounting and preventing the occurrence of defects due to wire bonding (for example, peeling of pad electrodes).

<Embodiment 1>
1A and 1B show a light-emitting diode 10 according to the first exemplary embodiment, and a second conductive semiconductor layer (in this example, an n-type semiconductor layer) made of a nitride semiconductor on the top surface of an insulator substrate 12 made of sapphire. 14 and a first conductivity type semiconductor layer (in this example, a p-type semiconductor layer) 16 are sequentially stacked to constitute a semiconductor stacked body 13.
In the p-type semiconductor layer 16, one of the corners (lower left corner in FIG. 1A) is partially removed, and the n-type semiconductor layer 14 exposed from the cut-out portion 32 also has a part of the thickness. Has been removed. A second translucent electrode (n-side translucent electrode in this example) 18 is formed on the upper surface of the n-type semiconductor layer 14 exposed from the cut portion 32, and a second translucent electrode 18 is formed on the upper surface of the p-type semiconductor layer 16 that has not been cut. One translucent electrode (p-side translucent electrode in this example) 20 is formed.
The “translucency” in the present invention means that the visible light transmittance is 50% or more.

  As shown in FIG. 1B, the cut portion 32 has a second through hole (in this example, an n side through hole) 24 that extends through the n-type semiconductor layer 14 and the substrate 12 to the lower surface side of the substrate 12. In addition, under the current diffusion portion 22, the semiconductor stacked body 13 (p-type semiconductor layer 16 and n-type semiconductor layer 14) and the substrate 12 are penetrated and extended to the lower surface side of the substrate 12. A first through hole (a p-side through hole in this example) 28 is formed. The inner surfaces of these through holes 24 and 28 are both covered with an insulating film 34, and the semiconductor laminate 13 and the through holes are electrically insulated.

  The insides of the n-side and p-side through holes 24 and 28 are filled with a translucent material, which is a second conductive portion (n-side conductive portion in this example) 26 and a first conductive portion (p-side in this example). (Conductive portion) 30 is configured. These conductive portions 26 and 30 have upper end portions connected to n-side and p-side translucent electrodes 18 and 20 formed on the upper surfaces of the semiconductor layers 14 and 16, and lower end portions that are substrates. 12 is reached.

  The n-side and p-side conductive portions 26 and 30 reaching the lower surface of the substrate 12 can be directly connected to the external electrodes 62 and 64 of the submount 60 by solder bumps or the like. In the light emitting diode 10 of the present embodiment, the lower surface of the substrate, which is the mounting surface, is flat, so that the light emitting diode 10 can be easily mounted flat, and the n-side conductive portion 26 and the p-side conductive portion 30 on the lower surface of the substrate are separated. Therefore, short circuit due to protrusion of solder bumps or the like hardly occurs. As described above, the light emitting diode 10 of the present invention is superior to the conventional light emitting diode in that wire bonding is not necessary while having ease of mounting similar to face-up mounting.

  In addition to directly connecting the n-side and p-side conductive portions 26 and 30 to the electrodes of the mounting substrate, an n-side lower surface electrode 36 and a p-side lower surface electrode 38 may be formed on the lower surface of the substrate and connected via them. it can. The n-side and p-side lower surface electrodes 36 and 38 in FIG. 1B are electrically connected to the lower ends of the n-side and p-side conductive portions 26 and 30 and are suitable for securing an area suitable for mounting.

  On the p-side translucent electrode 20, a current diffusion part 22 made of a translucent material can be formed. When a current is passed through the light emitting diode 10 of FIG. 1A, a large amount of current tends to concentrate at the shortest distance connecting the p-side conductive portion 26 formed at the upper right in the figure and the n-side conductive portion 30 formed at the lower left. There is. By providing the p-side translucent electrode 20, the current is broadened as a whole. However, the p-side translucent electrode 20 has a limited film thickness in order to ensure translucency. In some cases, it is not possible to make the resistance low enough to be spread sufficiently. In such a case, current diffusion by the p-side translucent electrode can be assisted by forming the current diffusion portion 22 extending to the lower right and upper left of the p-side translucent electrode. Since the current spreading part 22 is made of a light-transmitting material, the light emitted from the light emitting diode 10 can be taken out without being blocked. However, since it is laminated with the p-side translucent electrode 20, the translucency of the current diffusion portion 22 is lowered as compared with the case where only the p-side translucent electrode 20 is formed. Therefore, it is preferable to adjust the film thickness, shape, and the like of the current diffusion portion 22 according to the balance between the current diffusion effect and the light-transmitting property.

  As shown in FIG. 1B, when the light emitting diode 10 is mounted face-up on the submount 60, the n-side and p-side lower surface electrodes 36 and 38 are connected to the external electrodes 62 and 64 of the submount 60. As a mounting method, methods such as bump bonding, eutectic bonding, pressure bonding, and bonding with an anisotropic conductive material can be used. In the example of FIG. 1B, the lower surface electrodes 36 and 38 and the external electrodes 62 and 64 are joined by eutectic bonding to take electrical conductivity, and the light emitting diode 10 is fixed to the submount 60.

  When the light emitting diode 10 is energized, light is generated in an active layer (not shown) formed between the n-type semiconductor layer 14 and the p-type semiconductor layer 16, and is irradiated in the direction of arrow L shown in FIG. 1B. . That is, the upper surface of the light emitting diode 10 shown in FIG. 1A becomes the light emission observation surface, and light emission is observed from the entire region where the p-side translucent electrode 20 is formed. In particular, the current diffusing portion 22 forms a conductive portion of a translucent material on the p-side translucent electrode 20 so that the translucency is somewhat sacrificed compared to the p-side translucent electrode 20. The membrane resistance is lowered. As a result, the current is first spread by the current diffusion layer 22 and further spread from there to the entire surface by the translucent electrode 20. In the present invention, since both the p-side translucent electrode 20 and the current diffusion portion 22 are translucent, light generated in the active layer can be extracted from the entire surface without being blocked by the electrode. In particular, since light emitted directly under an electrode that has been completely shielded from light by an electrode can be extracted efficiently, the effect of improving the light extraction efficiency is remarkable. In the present invention, the area of the active layer is reduced by the formation of the p-side through hole 28, but the area is a dimension required for the through hole (a diameter of 50 μm or less is sufficient), and a conventional metal electrode (a diameter of 70 μm or more). Therefore, there is no possibility that the light extraction efficiency is lower than that of the conventional semiconductor light emitting device due to the formation of the through hole.

Further, in the light emitting diode 10 of the present invention, since the n-side translucent electrode 18 transmits visible light, part of the light propagating in the lateral direction while reflecting the inside of the semiconductor stacked body is converted to the n-side translucent The electrode 18 can be transmitted through and taken out. As a result, it is possible to alleviate luminance unevenness caused by light shielding of the negative electrode.
In addition, in the case where the n-type semiconductor layer includes a conventional negative electrode that does not transmit light in the lateral propagation of light, the laterally propagated light is reflected on the lower surface side of the negative electrode. Although it propagates further in the lateral direction, the final intensity of light that can be extracted due to loss of light due to the low reflectance of the negative electrode and attenuation when traveling inside the semiconductor is the light when it reaches the lower surface of the negative electrode. It becomes weaker than the strength of. However, in the light emitting diode 10 of the present invention, by providing the n-side translucent electrode 18 instead of the negative electrode, it is possible to extract the light before attenuation, thereby improving the light extraction efficiency.

  In mounting the light emitting diode 10, the light emitting diode 10 and the external electrodes 62 and 64 are electrically connected by a method such as eutectic bonding or bump bonding. Therefore, wire bonding is performed by stretching a metal wire over the upper surface of the light emitting diode 10. There is no need. Therefore, the mounting height of the light emitting diode 10 does not increase due to the protrusion of the metal wire in wire bonding, and the thickness of the light emitting device on which the semiconductor light emitting element is mounted can be reduced. Furthermore, since there is no metal wire crossing the light emitting surface, the light extraction efficiency can be improved. And since the defect resulting from wire bondings, such as cutting and peeling of a metal wire, does not occur, the defect rate can be reduced.

  Further, since the light emitting diode 10 of the present invention can be mounted without using wire bonding, there is a problem that the phosphor adheres to the metal wire when manufacturing a light emitting device in which a semiconductor light emitting element and a phosphor are combined. Therefore, there is no wire cutting failure or abnormal light emission along the wire. In addition, since the surface of the light emitting diode is uneven due to the metal wire, it is difficult to adhere the phosphor to the surface of the light emitting diode with a uniform thickness. Thus, there are problems such as uneven color and excessive deposition of phosphors. However, since the light emitting diode 10 of the present invention is mounted without using a metal wire, the phosphor can be deposited on the surface of the light emitting diode 10 with a uniform thickness, and an appropriate amount of phosphor can be deposited uniformly. Can do.

<Embodiment 2>
In the light emitting diode according to the second embodiment, the n-side and p-side conductive portions 26 and 30 are formed at different positions, and the shapes of the n-side translucent electrode 18 and the current diffusion layer 22 are changed accordingly. Except for this, it is the same as the first embodiment.
As shown in FIGS. 2A and 2B, the light emitting diode 10 of Embodiment 2 has a second groove portion (in this example, an n-side groove portion) 40 formed in one of the corner portions of the light-emitting diode 10, and the n-side groove. An insulating film 34 is formed on the inner wall of the portion 40, and a second conductive portion (n-side conductive portion in this example) 26 is formed inside the n-side groove portion 40. Further, a first groove portion (in this example, a p-side groove portion) 42 is formed at another corner portion, an insulating film 34 is formed on the inner wall of the p-side groove portion 42, and the first groove portion 42 has a first groove. A conductive portion (p-side conductive portion in this example) 30 is formed.

  The n-side translucent electrode 18 has an n-side extending portion 18 ′ that extends toward the corner of the light emitting diode 10 where the n-side conductive portion 26 is formed and is connected to the n-side conductive portion 26. ing. Further, the current diffusion layer 22 has a p-side extending portion 22 ′ that extends toward the corner portion where the p-side conductive portion 30 is formed and is connected to the p-side conductive portion 30. Thereby, the n-side translucent electrode 18 is electrically connected to the n-side conductive portion 26 via the n-side extending portion 18 ′, and the p-side translucent electrode 20 is connected to the current diffusion layer 22 and the p-side extending portion 22 ′. It is electrically connected to the p-side conductive portion 30 via the.

In the present embodiment, since the n-side and p-side conductive portions 26 and 30 are formed at the corners of the light emitting diode 10, the influence on the luminance distribution of the light emitting diode 10 is small.
In addition, when a large number of light emitting diodes are arranged on a wafer, through holes are formed in a portion where the corners of the four light emitting diodes are gathered, and then divided into individual chips to obtain a plurality of (this In the example, four grooves can be formed at the same time, and the manufacturing time can be shortened.

<Embodiment 3>
In the light emitting diode 10 according to the third embodiment, the cut portion 32 is formed in the substantially central portion of the p-type semiconductor layer 16, and accordingly, the exposed portion of the n-side semiconductor layer 14, the n-side translucent electrode. 18 and the shape and formation position of the n-side conductive portion 26 are changed. Further, in the present embodiment, the p-side conductive portion 30 is formed at the corner of the light emitting diode 10, and no current spreading portion is formed. Other configurations are the same as those in the first or second embodiment.

As shown in FIGS. 3A and 3B, in the light emitting diode 10 of Embodiment 3, the cut-out portion 32 is formed substantially at the center of the p-type semiconductor layer 16, and the n-type semiconductor layer exposed from the cut-out portion 32 is formed. An n-side translucent electrode 18 is formed on the surface 14.
An n-side through-hole 24 that extends through the n-type semiconductor layer 14 and the substrate 12 and extends to the lower surface side of the substrate 12 is formed substantially at the center of the n-side translucent electrode 18. An insulating film 34 and an n-side conductive portion 26 are formed inside the n-side through hole 24. The upper end of the n-side conductive portion 26 is connected to the n-side translucent electrode 18.

  A p-side groove portion 42 is formed at a corner of the light emitting diode 10, and an insulating film 34 and a p-side conductive portion 30 are formed inside the p-side groove portion 42. The upper ends of the four p-side conductive portions 30 are connected to the p-side translucent electrode 20.

  In the present embodiment, since the p-side translucent electrode 20 surrounds the entire periphery of the n-side conductive portion 26 and the n-side translucent electrode 18, the current flow of the p-side translucent electrode 20 It is easy to face the n-side translucent electrode 18 from all directions. Therefore, since the entire light emitting diode can be illuminated without providing the current diffusion portion, the manufacturing process of the current diffusion portion can be omitted, and the light transmission due to the p-side translucent electrode and the current diffusion portion being laminated. Since there is no decrease in light properties, the light extraction efficiency can be increased.

  In order to uniformly illuminate the light emitting diode, it is ideal to pass a current through the active layer at all positions. However, in a light emitting diode having a conventional pad electrode, the size of the pad electrode is limited (to the extent that wire bonding is possible). The electrode arrangement is limited by having an area. On the other hand, since the present invention does not require wire bonding, it is possible to freely change the shape and formation position of the electrodes, thereby improving the efficiency of current diffusion.

  FIG. 3C is a modification of the light-emitting diode 10 according to Embodiment 3. FIG. 3A is different from FIG. 3A in that the p-side groove portion 42, the insulating film 34, and the p-side conductive portion 30 formed at the corners of the light-emitting diode 10 It differs in that it is formed on the side of the light emitting diode. Thus, in the light emitting diode 10 of Embodiment 3, the p-type conductive part 30 can also be formed on the side part. In this figure, the p-side conductive portion 30 is formed at the approximate center of the side portion, but can also be formed at a position shifted from the center.

  The transformation from FIG. 3A to FIG. 3C is very easy. With reference to FIG. 3D, an example of a method for forming the p-side conductive portion 30 when manufacturing the light emitting diode 10 of FIGS. 3A and 3C will be described. FIG. 3D shows a state in which a large number of light emitting diodes 10 are formed on one substrate, and shows a state before being divided into individual light emitting diode chips. In the light emitting diode 10 having the p-side conductive portion 30 at the corner as shown in FIG. 3A, the p-side through hole is formed at the position A where the corners of the four light-emitting diodes 10 gather, and the insulator film 34, The p-side conductive part 30 is filled. On the other hand, in the light emitting diode 10 with the p-side conductive portion 30 on the side as shown in FIG. 3C, a p-side through hole is formed at a position C where the sides of the two light-emitting diodes 10 are in contact with each other. The insulator film 34 and the p-side conductive portion 30 are filled. Thereafter, by dividing the light emitting diode 10 into individual chips, it is possible to obtain the light emitting diode 10 having the p-side conductive portion 30 at the corner or side.

  In the third embodiment, the p-side conductive portion 30 is formed on all four corners or all four sides. However, the p-side conductive portion 30 is not necessarily formed on all four locations. Some of them can be selected and formed. Furthermore, you may form the n-type electroconductive part 26 in both a corner | angular part and a side part. These are placed as long as the p-side conductive portion 30 and the p-side translucent electrode 20 arranged in the p-side groove portion 42 are surely connected to each other. It can be arbitrarily changed in consideration of easiness, conductivity of the conductive portion, and the like.

<Embodiment 4>
In the light emitting diode 10 according to the fourth embodiment, a cut portion 32 is formed at the periphery of the p-type semiconductor layer 16, and accordingly, the exposed portion of the n-side semiconductor layer 14, the n-side translucent electrode 18, And the shape and formation position of the n-side conductive portion 26 are changed. Further, in the present embodiment, the p-side conductive portion 30 is formed almost at the center of the p-side translucent electrode, and no current diffusion portion is formed. Other configurations are the same as in the first to third embodiments.

As shown in FIGS. 4A and 4B, the light-emitting diode 10 of Embodiment 4 has a cutout 32 formed at the periphery of the p-type semiconductor layer 16, and the n-type semiconductor layer 14 exposed from the cutout 32. An n-side translucent electrode 18 is formed on the surface. That is, the n-side translucent electrode 18 is shaped so as to surround the p-type semiconductor layer 16.
An n-side groove portion 40 is formed at a corner portion of the light emitting diode 10, and an insulating film 34 and an n-side conductive portion 26 are formed inside the n-side groove portion 40. The upper ends of the four n-side conductive portions 26 are connected to the n-side translucent electrode 18.

  Near the center of the p-side translucent electrode 20 is a p-side through hole that extends through the semiconductor laminate 13 (p-type semiconductor layer 16 and n-type semiconductor layer 14) and the substrate 12 to the lower surface side of the substrate 12. 28 is formed. An insulating film 34 and a p-side conductive portion 30 are formed inside the p-side through hole 28. The upper end of the p-side conductive portion 30 is connected to the p-side translucent electrode 20.

  In the present embodiment, since the n-side translucent electrode 18 surrounds the entire periphery of the p-side conductive portion 30 and the p-side translucent electrode 20, the current flow is omnidirectional from the p-side conductive portion 30. It is easy to face the n-side translucent electrode 18. Therefore, since the entire light emitting diode can be illuminated without providing the current diffusion portion, the manufacturing process of the current diffusion portion can be omitted, and the light transmission due to the p-side translucent electrode and the current diffusion portion being laminated. Since there is no decrease in light properties, the light extraction efficiency can be increased. Further, since the light emitting diode 10 is formed around the cut portion 32, the central portion of the light emitting diode 10 emits light except for the through holes 28, and has an extremely excellent luminance distribution.

  In order to uniformly illuminate the light emitting diode, it is ideal to pass a current through the active layer at all positions. However, in a light emitting diode having a conventional pad electrode, the size of the pad electrode is limited (to the extent that wire bonding is possible). The electrode arrangement is limited by having an area. On the other hand, since the present invention does not require wire bonding, it is possible to freely change the shape and formation position of the electrodes, thereby improving the efficiency of current diffusion.

  In the fourth embodiment, the p-side conductive portion 30 is formed at all four corners. However, the p-side conductive portion 30 is not necessarily formed at all four corners, and some of the corners are selected. It can also be formed. Further, similarly to the p-side conductive portion 30 in FIG. 3C, the n-type conductive portion 26 can be formed on the side portion. Further, the n-type conductive portion 26 may be formed on both the corner and the side. These are placed as long as the n-side conductive portion 26 and the n-side translucent electrode 18 disposed in the n-side groove 40 are surely connected to each other. It can be arbitrarily changed in consideration of easiness, conductivity of the conductive portion, and the like.

In the first to fourth embodiments, the p-side translucent electrode 20 is formed in direct contact with the upper surface of the p-type semiconductor layer 16, but the p-type semiconductor layer 16 and the p-side translucent electrode 20 A conductive layer or another semiconductor layer (including other than the p-type semiconductor layer) may be interposed therebetween. The layer that can be interposed has electrical conductivity and material characteristics that can establish electrical conduction between the p-type semiconductor layer 16 and the p-side translucent electrode 20, and translucency. Although necessary, as long as it has these properties, it can be intervened, whether it is a single layer or a multilayer.
In the first to fourth embodiments, a semiconductor light emitting device using a p-type semiconductor layer 16 as a first conductive semiconductor layer and an n-type semiconductor layer as a second conductive semiconductor layer is disclosed. The invention also includes a semiconductor light emitting device in which a p-type semiconductor layer and an n-type semiconductor layer are interchanged.

Below, the material suitable for using for Embodiment 1-4 is demonstrated.
(N-side translucent electrode 18)
The n-side translucent electrode 18 is formed of a translucent material that transmits visible light and can make ohmic contact with the n-side semiconductor layer 14. Examples of the translucent material forming the n-side translucent electrode 18 include a metal thin film and a conductive oxide film.
As the metal thin film, a thin film having a thickness of 50 to 300 mm made of metal such as Ti / Au is suitable.
As the conductive oxide film, an oxide film containing at least one element selected from the group consisting of zinc (Zn), indium (In), tin (Sn), and magnesium (Mg) is suitable. . Specifically, ZnO, AZO (Al-doped ZnO), IZO (In-doped ZnO), GZO (Ga-doped ZnO), In ₂ O ₃ , ITO (Sn-doped In ₂ O ₃ ), IFO (F-doped In ₂ O ₃ ), SnO ₂ , ATO (Sb-doped SnO ₂ ), FTO (F-doped SnO ₂ ), CTO (Cd-doped SnO ₂ ), MgO, and the like. These materials can be formed by a physical film formation method (evaporation, sputtering, pulsed laser ablation (PLD), etc.) or a chemical film formation method (sol gel, spray, etc.).

(P-side translucent electrode 20)
The p-side translucent electrode 20 is also formed of a translucent material that transmits visible light and can make ohmic contact with the p-type semiconductor layer 16. Examples of the translucent material for forming the p-side translucent electrode 20 include a metal thin film and a conductive oxide film.
As the metal thin film, a thin film having a thickness of 50 to 300 mm made of metal such as Ni / Au is suitable.
As the conductive oxide film, an oxide film containing at least one element selected from the group consisting of zinc (Zn), indium (In), tin (Sn), and magnesium (Mg) is suitable. . Specifically, ZnO, AZO (Al-doped ZnO), IZO (In-doped ZnO), GZO (Ga-doped ZnO), In ₂ O ₃ , ITO (Sn-doped In ₂ O ₃ ), IFO (F-doped In _2). O ₃ ), SnO ₂ , ATO (Sb doped SnO ₂ ), FTO (F doped SnO ₂ ), CTO (Cd doped SnO ₂ ), MgO, and the like. These materials can be formed by a physical film formation method (evaporation, sputtering, pulsed laser ablation (PLD), etc.) or a chemical film formation method (sol gel, spray, etc.).
The n-side translucent electrode 18 and the p-side translucent electrode 20 can be formed from different translucent materials. However, if the same material is selected, there is an advantage that films can be formed simultaneously in the manufacturing process. is there.

(N-side conductive portion 26 and p-side conductive portion 30)
The n-side conductive portion 26 and the p-side conductive portion 30 are formed from a light-transmitting material having conductivity, and can be formed from, for example, a conductive oxide. Since the n-side and p-side conductive portions 26 and 30 penetrate the inside of the light-emitting diode 10, if they are formed from an opaque conductive material, the light from the active layer may be prevented from propagating in the lateral direction. Depending on the case, light may be absorbed, which is not preferable.
Examples of the conductive oxide suitable for the n-side conductive portion 26 and the p-side conductive portion 26 include conductive oxides that can be used for the n-type translucent electrode and the p-side translucent electrode.
Note that the n-side conductive portion 26 and the p-side conductive portion 30 can be formed from different light-transmitting materials, but if formed from the same material, there is an advantage that films can be formed simultaneously in the manufacturing process. Furthermore, if these conductive portions 26 and 30 and the n-side and p-side translucent electrodes 18 and 20 are all formed from the same material, the number of manufacturing steps can be further reduced.

(N-side lower surface electrode 36 and p-side lower surface electrode 38)
The n-side lower surface electrode 36 and the p-side lower surface electrode 38 are preferably formed from a material suitable for the mounting method on the submount 60. For example, when mounting to the external electrodes 62 and 64 of the submount 60 by bump bonding, it is suitable that the n-side and p-side lower surface electrodes 36 and 38 are metal thin films made of a metal material such as Ag or Al. In mounting by eutectic bonding, it is preferable to use a laminate of metal thin films such as Au / Sn. In mounting using an anisotropic conductive material in which conductive particles are dispersed in a resin sheet or resin paste, it is suitable that the n-side and p-side lower surface electrodes 36 and 38 are metal thin films made of a metal material such as Ag or Al. ing. The n-side and p-side lower surface electrodes 36 and 38 can also be formed from a conductive oxide. In that case, the external electrode 62 can also be manufactured from a conductive oxide, and can be mounted by aligning the n-side and p-side lower surface electrodes 36 and 38 and the external electrode 62 at the time of mounting and thermocompression bonding.

<Method for Manufacturing Light-Emitting Diode 10>
A manufacturing method will be described by taking Embodiment 2 (light emitting diode 10 shown in FIGS. 2A and 2B) as an example. 5A to 5G show the manufacturing process of the light emitting diode 10 as observed from the same cross section as FIG. 2B.

First, an n-type semiconductor layer 14 and a p-type semiconductor layer 16 were sequentially stacked on a substrate 12 made of an insulator to form a semiconductor stacked body 13. A laser beam was irradiated from the semiconductor laminate 13 side to form a hole 70 having a diameter of about 50 μm (FIG. 5A). In addition, since melt (debris) adheres to the inner wall of the hole after laser irradiation, it is preferable to remove it by etching with a phosphoric acid solution.
Next, from the inner surface of the formed hole 70 to the edge of the opening of the hole 70 was covered with an insulating film 34 (FIG. 5B), and a part of the surface of the p-type semiconductor layer 16 was removed, The entire surfaces of the p-type semiconductor layer 16 and the insulating film 34 were covered with a light-transmitting conductive film 72 (FIG. 5C). Then, if necessary, annealing treatment was performed to obtain ohmic contact between the translucent conductive film 72 and the p-side semiconductor layer 16.

In FIG. 5C, the surface of the p-type semiconductor layer 16 on which the translucent conductive film 72 was not formed was etched by RIE to form a cut portion 32 (FIG. 5D). The cut portion 32 was formed in the vicinity of the hole portion 70 (on the left side of the hole portion 70 in FIG. 5D).
Then, the n-side translucent electrode 18 was formed so as to cover from the surface of the n-type semiconductor layer 14 exposed from the cut portion 32 to a part of the translucent conductive film 72. The n-side translucent electrode 18 formed in this way was electrically connected to the translucent conductive film 72.

Thereafter, the lower surface side of the substrate 12 was polished to penetrate the hole 70 (FIG. 5F). At this time, the hole 70 penetrates, so that the lower ends of the insulating film 34 and the translucent conductive film 72 that were closed in the hole 70 were also opened.
Finally, the substrate 12 and the n-side and p-side semiconductor layers 14 and 16 were separated into chips by scribing or the like to obtain the light emitting diode 10 (FIG. 5G).

  5A to 5G show a method for manufacturing the light emitting diode 10 in which the bottom electrode and the current diffusion layer are not formed. By adding a simple process to this manufacturing method, the bottom electrode and the current diffusion layer are formed. Can be formed. Below, the example of the formation process of the lower surface electrode for eutectic bonding is demonstrated.

  5A to 5F, the n-side and p-side semiconductor layers 14 and 16, the translucent conductive film 72, and the hole 70 are covered with a resist film 74, as shown in FIG. 6A. Protected from. A eutectic layer 76 was formed on the lower surface side of the substrate 12 so as to cover the opening at the lower end of the hole 70 (FIG. 6B). The hole 70 exposed on the lower surface side of the substrate 12 is formed with the insulator film 34 and the translucent conductive film 72 therein, so that the eutectic layer 76 and the translucent conductive film 72 are electrically connected. It will be.

  Then, as shown in FIG. 6C, the resist film 74 is peeled off, and then the substrate 12 and the n-side and p-side semiconductor layers 14 and 16 are separated into chips by scribing or the like to obtain the light emitting diode 10 having the lower surface electrode. (FIG. 6D).

Other than the manufacturing method as shown in FIGS. 5A to 5G, the light emitting diode 10 of the present invention can be manufactured by combining known techniques.
As a modification of the simple manufacturing method, as shown in FIGS. 5C to 5D, instead of forming the cut portion 34 after forming the translucent conductive film 72, the cut portion 34 is formed first, and thereafter A light-transmitting conductive film 72 can also be formed.

Further, although the hole 70 is formed by the laser beam in FIG. 5A, microblasting can be used instead. In this method, first, a dry film resist is laminated on the upper surface of the semiconductor laminate 13, and the resist at the position where the hole 70 is formed is removed by a photolithography technique. Then, microblasting for injecting fine particles is performed to form a hole 70 in the resist removal portion. In this microblasting process, a hole 70 having a smaller diameter (about 20 μm) than the laser beam can be formed. Such a small-diameter hole 70 is suitable for forming the n-side and p-side through holes 24 and 28 as in the first, third, and fourth embodiments, for example, and is the active layer removed by the through holes. The area can be reduced, and the light amount of the light emitting diode 10 can be increased.

1 is a schematic top view of a light emitting diode according to a first embodiment. It is a schematic sectional drawing of the light emitting diode along the AA line of FIG. 1A. FIG. 3 is a schematic top view of a light emitting diode according to a second embodiment. It is a schematic sectional drawing of the light emitting diode along the BB line of FIG. 2A. FIG. 6 is a schematic top view of a light emitting diode according to a third embodiment. It is a schematic sectional drawing of the light emitting diode along CC line of FIG. 3A. FIG. 10 is a schematic top view showing a modification of the light emitting diode according to the third embodiment. It is a schematic top view explaining the manufacturing method of FIG. 3A and FIG. 3C. FIG. 6 is a schematic top view of a light emitting diode according to a fourth embodiment. It is a schematic sectional drawing of the light emitting diode along the DD line | wire of FIG. FIG. 10 is a schematic cross-sectional view for explaining the manufacturing process for the light-emitting diode according to the second embodiment. FIG. 10 is a schematic cross-sectional view for explaining the manufacturing process for the light-emitting diode according to the second embodiment. FIG. 10 is a schematic cross-sectional view for explaining the manufacturing process for the light-emitting diode according to the second embodiment. FIG. 10 is a schematic cross-sectional view for explaining the manufacturing process for the light-emitting diode according to the second embodiment. FIG. 10 is a schematic cross-sectional view for explaining the manufacturing process for the light-emitting diode according to the second embodiment. FIG. 10 is a schematic cross-sectional view for explaining the manufacturing process for the light-emitting diode according to the second embodiment. FIG. 10 is a schematic cross-sectional view for explaining the manufacturing process for the light-emitting diode according to the second embodiment. FIG. 10 is a schematic cross-sectional view for explaining a step of forming a lower surface electrode of a light emitting diode according to a second embodiment. FIG. 10 is a schematic cross-sectional view for explaining a step of forming a lower surface electrode of a light emitting diode according to a second embodiment. FIG. 10 is a schematic cross-sectional view for explaining a step of forming a lower surface electrode of a light emitting diode according to a second embodiment. FIG. 10 is a schematic cross-sectional view for explaining a step of forming a lower surface electrode of a light emitting diode according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light emitting diode 12 Board | substrate 13 Semiconductor laminated body 14 2nd conductivity type semiconductor layer (n-type semiconductor layer)
16 First conductivity type semiconductor layer (p-type semiconductor layer)
18 Second translucent electrode (n-side translucent electrode)
20 1st translucent electrode (p side translucent electrode)
22 Current diffusion portion 24 Second through hole (n-side through hole)
26 Second conductive part (n-side conductive part)
28 1st through hole (p side through hole)
30 1st conductive part (p side conductive part)
32 Cutout 34 Insulating film 36 n-side bottom electrode 38 p-side bottom electrode

Claims (4)

A laminated body in which a substrate, an n-type nitride semiconductor layer, and a p-type nitride semiconductor layer are sequentially laminated from the lower surface side to the upper surface side;
A p-side translucent electrode provided on the upper surface of the p-type nitride semiconductor layer;
A translucent current spreading portion provided on the upper surface of the p-side translucent electrode;
The current diffusion portion and are electrically connected to the p Gawashirube conductive portion extending to the lower side from the upper surface side of the laminate, a manufacturing method of the semiconductor light emitting element Ru with a
The n-type nitride semiconductor layer and the p-type nitride semiconductor layer are sequentially stacked on the substrate to form the stacked body, and then reach the middle of the thickness of the substrate from the p-type nitride semiconductor layer side. A hole is formed, the inner surface of the hole to the edge of the opening is covered with an insulating film, and is made of a conductive oxide for constituting the p-side translucent electrode and the p-side conductive portion. A translucent conductive film is formed so as to cover the insulating film and extend to the upper surface of the p-type nitride semiconductor layer;
Then, after polishing the lower surface side of the substrate to penetrate the hole and opening the lower end of the insulating film and the translucent conductive film, individual semiconductor light emission along the line passing through the through hole by dividing the elements, the p and Gawashirubeden unit, before Symbol semiconductor side portions of the light-emitting element or located corner from the lower surface of the substrate the p-type light-transmissive electrode to extend to the p-side groove of inside, a method of manufacturing a semiconductor light emitting device lower end of that is characterized by forming with an insulating film that matches the bottom surface of the substrate. An n-side translucent electrode provided on the n-type nitride semiconductor layer partially exposed on the upper surface side of the stacked body;
The method for manufacturing a semiconductor light-emitting element according to claim 1, further comprising: a translucent n-side conductive portion extending from the n-side translucent electrode to the lower surface of the substrate. The n-side conductive portion is
(A) From the lower surface of the substrate to the inside of the n-side through-hole penetrating the n-side translucent electrode, or (b) From the lower surface of the substrate located at a side or corner of the semiconductor light emitting device Inside the n-side groove extending to the n-side translucent electrode,
The method of manufacturing a semiconductor light emitting element according to claim 2, wherein the semiconductor light emitting element is formed through the insulating film . 4. The lower surface electrode connected to the p-type conductive portion or the n-side conductive portion is formed on the lower surface side of the substrate after the lower end portion of the insulating film is opened. 5. Manufacturing method of the semiconductor light-emitting device.

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