KR100863805B1 - Gallium nitride light emitting diode and method for manufacturing the same - Google Patents

Abstract

A gallium nitride light emitting diode and a manufacturing method thereof are provided to minimize damage thereof by isolating a substrate and a nitride layer from each other. An N type nitride semiconductor layer(42), an active layer(43), and a P type nitride semiconductor layer(44) are formed on a sapphire substrate(41). A P type electrode layer(45) is formed on the P type nitride semiconductor layer. A sub-mount substrate(47) is bonded on the P type nitride semiconductor layer. An isolation layer(42s) is formed in the inside of the N type nitride semiconductor layer. The sapphire substrate is isolated from the nitride semiconductor layer. An N type electrode layer is formed on the N type nitride semiconductor layer in order to manufacture an LED chip.

Description

Nitride light emitting device and method for manufacturing the same

1 is a view showing the structure of a top-emitting light emitting device according to the prior art.

2 is a view showing the structure of a light emitting device manufactured using a flip chip bonding method according to the prior art.

3A to 3D illustrate a method of manufacturing a light emitting device according to a first embodiment of the present invention.

4A to 4D illustrate a method of manufacturing a light emitting device according to the first embodiment of the present invention.

The present invention relates to a nitride light emitting device and a method of manufacturing the same, and more particularly to a method for manufacturing a nitride light emitting device by separating the nitride and nitride grown substrate by implanting ions and a nitride light emitting device manufactured using the same It is about.

A light emitting diode (LED) device is a semiconductor device that generates light by flowing current in a forward direction to a PN junction.

LEDs using semiconductors have high efficiency in converting electrical energy into light energy, have a long lifespan of more than 5 to 10 years, and can greatly reduce power consumption and maintenance costs. I am getting it.

A sapphire substrate is mainly used for growth of a gallium nitride compound semiconductor for manufacturing a light emitting diode. Since the sapphire substrate is an insulator, the anode and cathode electrodes of the light emitting diode are formed on the front surface of the wafer.

1 is a view showing the structure of a conventional top-emitting light emitting diode. Referring to FIG. 1, in the top-emitting LED, an N-type nitride semiconductor layer 12, an active layer 13, and a P-type nitride semiconductor layer 14 are formed on a sapphire substrate 11 to form a nitride layer. After etching a portion of the nitride layer to expose the N-type nitride semiconductor layer 2, the electrode layers 15 and 16 are formed on the P-type nitride semiconductor layer 14 and the etched N-type nitride semiconductor layer 16, respectively. do.

At this time, the electrode layers 15 and 16, in particular, the P-type electrode layer 15 may be Ni / Au, except for regions where wire bonding is required to increase the current injection area while improving the transmittance of light generated in the active layer 13. It can also be formed from a transparent electrode layer such as ITO.

In general, a top-emitting gallium nitride-based light emitting diode is mainly used for low power, and the chip is manufactured by thinning the sapphire substrate to a thickness of about 100 microns or less in order to improve heat emission efficiency.

However, since the thermal conductivity of the sapphire substrate is about 50 W / mK, even if the thickness is about 100 microns, the thermal resistance is very large, so that even with the structure shown in FIG.

Meanwhile, in the case of a high output gallium nitride-based light emitting diode, a flip chip bonding method is mainly used as shown in FIG. 2 to further improve heat dissipation characteristics.

In the flip chip bonding method, a chip having a light emitting diode structure is attached to a submount substrate such as a silicon wafer (about 150 W / mK) or an AlN ceramic (about 180 W / mK) substrate having excellent thermal conductivity.

Referring to FIG. 2, which shows a cross section of a state in which a conventional light emitting diode is flip chip bonded, the flip chip bonded light emitting diode is basically a sapphire substrate 21 and an N-type nitride semiconductor layer on the sapphire substrate 21. (22), the active layer 23 and the P-type nitride semiconductor layer 24 are sequentially stacked to form a light emitting structure, and the P-type electrode 25 and the N-type nitride semiconductor layer 22 at predetermined positions on the light emitting structure. And an N-type electrode 26 formed in a predetermined region on the top surface and used for bonding and voltage application.

Such a light emitting diode places solder bumps 29 formed on the P-type electrode 25 and the N-type electrode 26 to be directly bonded to the silicon submount 27. At this time, the P-type electrode 25 and the N-type electrode 26 are connected to the positive electrode 28b and the negative electrode 28a formed in the silicon submount 27 through the solder bumps 29, respectively.

In this case, since the heat is released through the submount substrate, the heat dissipation efficiency is improved as compared with the heat dissipation through the sapphire substrate, but the degree of improvement is not satisfactory.

In relation to these problems, recently, a thin film gallium nitride based light emitting diode (thin GaN LED) method in which a sapphire substrate has been removed has been attracting attention. The light emitting diode manufacturing method by removing the sapphire substrate is a typical technique of removing the sapphire substrate and packaging by laser lift-off method from the light emitting diode crystal structure and is known as the structure having the best heat dissipation efficiency.

In addition, unlike the flip chip bonding method, the sapphire substrate removing method does not require an elaborate flip chip bonding process, and the manufacturing process is simple as long as the problem related to the removal of the sapphire substrate is solved.

In the case of the flip chip type, the light emitting area is about 60% of the chip area, whereas in the thin film type light emitting diode structure in which the sapphire substrate is removed, the light emitting area is about 90% of the size of the chip. Has excellent properties.

However, in spite of these advantages, the conventional laser lift-off method, which is typically used to remove the sapphire substrate, not only requires expensive laser equipment, but also requires a long manufacturing process and simply separates the gallium nitride layer from the sapphire substrate. There is a problem that does not perform the above function.

In addition, during laser irradiation, thermal damage occurs in the nitride layer in contact with the sapphire substrate, which not only adversely affects ohmic characteristics when the electrode layer is formed in the nitride layer, but also between the sapphire substrate and the light emitting diode crystal structure. Since cracking occurs in the light emitting diode crystal structure due to stress, the yield is remarkably decreased even though the heat dissipation efficiency is excellent.

In addition, mechanical stress is generated in the interface and nitride semiconductor devices by nitrogen generated when GaN is separated, so that a crack occurs in the device in severe cases. Also, Ga agglomerations generated during separation are formed on the surface of the nitride layer. Thermal damage caused by a laser is present in the nitride layer, and the crystalline structure of the nitride semiconductor layer is damaged or, in extreme cases, device characteristics are deteriorated due to damage to the active layer where light is generated.

Accordingly, there is a need for a manufacturing method capable of mass-producing a thin-film gallium nitride-based light emitting diode from which a sapphire substrate having excellent characteristics such as luminous efficiency and heat emission efficiency is removed.

The technical problem to be achieved by the present invention is to solve the problems caused when manufacturing a thin film light emitting device using a conventional laser, a method of manufacturing a nitride light emitting device that can maximize the luminous efficiency with high reliability and low cost and the same It is to provide a nitride light emitting device manufactured using.

In order to achieve the above technical problem, the present invention injects ions to a nitride layer to a predetermined depth to form a separation layer inside the nitride layer, and performs a heat treatment on the substrate on which the nitride layer is formed to separate the substrate and the nitride layer from the separation layer. The present invention provides a method of manufacturing a thin film nitride light emitting device without performing a separate laser off process.

The light emitting device manufacturing method of the present invention for achieving the above technical problem, (a) forming a nitride layer on a predetermined substrate; (b) implanting predetermined ions through the substrate into the nitride layer to form a separation layer; And (c) heat treating the substrate on which the nitride layer is formed to separate the substrate and the nitride layer from the separation layer.

Further, in the above-described step (a), sequentially forming a first nitride semiconductor layer, an active layer, and a second nitride semiconductor layer on the substrate, and bonding the submount substrate on the second nitride semiconductor layer. It may include.

In addition, in step (a), the first nitride semiconductor layer, the active layer, and the second nitride semiconductor layer may be sequentially formed on the substrate, and in step (b), the separation layer may be formed on the first nitride semiconductor layer. Can be formed.

In addition, in step (b) described above, the separation layer may be formed to have a uniform depth over the entire area of the nitride layer.

In addition, in step (b) described above, the separation layer may be formed to have a non-uniform depth over the entire area of the nitride layer.

In addition, in step (b) described above, the separation layer may be formed to have a curvature by adjusting the ion implantation conditions.

In addition, in step (b) described above, the separation layer may be formed to have irregularities.

In addition, in the step (b) described above, the implantation amount, implantation depth, and implantation depth for implanting ions into the nitride layer according to the region into which ions are implanted so as to have a texturing effect on the surface of the nitride layer after the substrate is separated from the separation layer, One or more of the implantation energy may be adjusted to implant ions into the nitride layer.

In addition, in step (b) described above, ions may be implanted using a shadow mask or a photo resist.

In addition, the above-described light emitting device manufacturing method may further include (d) forming an electrode layer on the nitride layer.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

3A to 3D illustrate a method of manufacturing a nitride light emitting device according to the first embodiment of the present invention. Referring to FIGS. 3A to 3D, first, as shown in FIG. 3A, an N-type nitride semiconductor layer (first nitride semiconductor layer) 32, an active layer 33, and a light emitting device manufacturing substrate 31 may be formed. And a P-type nitride semiconductor layer (second nitride semiconductor layer; 34) are sequentially stacked to form a nitride layer.

In this case, the present invention uses the sapphire substrate 31 as the light emitting device manufacturing substrate 31, but other substrates may be used in addition to the sapphire substrate, sapphire substrate 31 is exemplarily described for convenience of description. Explain. In addition, the method of forming a nitride layer can be formed using well-known methods, such as a conventional MOCVD method.

After the nitride layer is formed, the P-type electrode layer 35 is formed on the P-type nitride semiconductor layer 44. The P-type electrode layer 35 is preferably composed of a hydrogen storage alloy layer, a transparent electrode layer (TCO), and a reflective film layer. After the P-type electrode layer 35 is formed, a submount substrate 37 made of a conductive material such as silicon or metal is bonded onto the P-type electrode layer 35.

After the submount substrate 37 is bonded to the P-type electrode layer 35, ions are implanted through the sapphire substrate 31 to separate the sapphire substrate 31 and the nitride layer from each other, as shown in FIG. 3B. The isolation layer 32s is formed in the N-type nitride semiconductor layer 32 at a uniform depth.

Specifically, the present invention transmits 1 × 10 ¹⁶ ions / cm 2 to 10 × 10 ¹⁶ ions / cm 2 of hydrogen ions through an sapphire substrate with an implantation energy of 10 KeV to 200 KeV to separate the separation layer 32s on the N-type nitride semiconductor layer 32. ) Was formed. In this case, a separation layer 32s was formed at a depth of about 1000 to 9000 kPa into the first nitride semiconductor layer 32 from the boundary between the N-type nitride semiconductor layer 32 and the sapphire substrate. The depth at which the separation layer 32s is formed can be adjusted by changing ion implantation conditions. In addition, although the present invention used hydrogen ions as implanted ions, ions such as nitrogen and argon may be used.

After the separation layer 32s is formed on the nitride layer, as shown in FIG. 3C, the sapphire substrate on which the nitride layer is formed is heat-treated at a predetermined temperature for a predetermined time to separate the sapphire substrate and the nitride layer. In the preferred embodiment of the present invention, the nitride layer and the silicon substrate are separated from the separation layer 32s by performing heat treatment in the temperature range of about 300 to 600 ° C. for about 10 to 30 minutes. As the microcracks are formed by the hydrogen ions injected into the separation layer, the separation layer 32s is broken to separate the nitride layer and the sapphire substrate.

After the substrate and the nitride layer are separated, as shown in FIG. 3D, an N-type electrode layer 36 is formed on the N-type nitride semiconductor layer 32 to manufacture an LED chip.

As described so far, the first embodiment of the present invention forms an isolation layer 32s by implanting ions into the N-type nitride semiconductor layer 32, and separates the substrate and nitride layer from the isolation layer 32s, Compared to the conventional technology of manufacturing a thin film light emitting device by separating a substrate and a nitride layer by using an excimer laser or the like, the thin film light emitting without deterioration of ohmic characteristics in the N-type electrode region caused by thermal damage of the laser lift-off process at low cost There is an effect that can produce a device.

In addition, as described above, the present invention has an effect of controlling the thickness of the first nitride semiconductor layer after substrate separation by adjusting the depth at which the isolation layer 32s is formed, and thus, the thickness of the first nitride semiconductor layer is increased. By thinning, not only the effect of facilitating heat dissipation generated in the light emitting device, but also the amount of light absorbed by the substrate is reduced, thereby improving the light efficiency of the entire foot and the device.

4A to 4D illustrate a method of manufacturing a nitride light emitting device according to a second exemplary embodiment of the present invention. The second embodiment differs only in the method of forming the separation layer from the first embodiment. Therefore, the following description focuses on the differences from the first embodiment and briefly describes the same contents.

In the same manner as in the first embodiment, as shown in FIG. 4A, the sapphire substrate 41 has an N-type nitride semiconductor layer (first nitride semiconductor layer; 42), an active layer 43, and a P-type nitride semiconductor layer ( The second nitride semiconductor layer 44 is sequentially stacked to form a nitride layer.

After the nitride layer is formed, the P-type electrode layer 45 is formed on the P-type nitride semiconductor layer 44. The P-type electrode layer 45 is preferably composed of a hydrogen storage alloy layer, a transparent electrode layer (TCO), and a reflective film layer. After the P-type electrode layer 45 is formed, a submount substrate 47 made of a conductive material such as silicon or metal is bonded onto the P-type electrode layer 45.

After the submount substrate 47 is bonded to the P-type electrode layer 45, ions are implanted through the sapphire substrate 41 to separate the sapphire substrate 41 and the nitride layer from each other, as shown in FIG. 4B. As a result, a separation layer 42s is formed inside the N-type nitride semiconductor layer 42.

However, unlike the first embodiment in which the separation layer 42s is formed flat with a uniform depth, in the second embodiment, the ions implanted along the region of the N-type nitride semiconductor layer 42 into which the ions are implanted are Ion implantation parameters such as amount and ion implantation energy, depth at which ions are implanted, and the like are implanted to implant ions such that the isolation layer 42s is formed at a non-uniform depth, i.e., uneven, as shown in FIG. 4B. do. Therefore, the separation layer 42s is formed to have irregularities, and may be formed to have regular curvatures as shown in FIG. 4B, or may be formed to have irregular protrusions and grooves, and the shape of the protrusions and grooves may be sharply formed. It may be. Hereinafter, the case where the separation layer 42s is formed to have regular bending will be described as an example.

In order to form a bend in the separation layer 42s, ions may be implanted in various ways. For example, when ions are implanted by a line scanning method, ions are deeply implanted by increasing ion implantation energy and ion implantation amount in one line, In the next line, the ion implantation energy and the ion implantation amount are reduced to inject ions shallowly, and the depth of the separation layer 42s can be controlled by repeating this method constantly. In addition, the ion may be implanted using a photoresist or a shadow mask during ion implantation, and the shape of the bend formed in the separation layer 42s may be a predetermined pattern or an arbitrary pattern.

In addition, in the second embodiment of the present invention, like the first embodiment, an N-type nitride semiconductor is formed by passing hydrogen ions having a size of 1 × 10 ¹⁶ ions / cm 2 to 10 × 10 ¹⁶ ions / cm 2 through a sapphire substrate with an implantation energy of 10 KeV to 200 KeV. A separation layer 42s was formed in layer 42. In this case, a separation layer 42s was formed at a depth of about 1000 to 9000 kPa into the first nitride semiconductor layer 42 from the boundary between the N-type nitride semiconductor layer 42 and the sapphire substrate.

After the separation layer 42s is formed on the nitride layer, as shown in FIG. 4C, the sapphire substrate on which the nitride layer is formed is heat-treated at a predetermined temperature for a predetermined time to separate the sapphire substrate and the nitride layer. The manner and function of carrying out the heat treatment are the same as in the first embodiment.

When the substrate 41 is separated, the surface (separation surface) of the N-type nitride semiconductor layer 42 is formed in the same shape as the bend formed in the separation layer 42s, and this separation surface is light generated in the active layer 43. It totally reflects from this surface and prevents it from flowing back into the device, thereby improving the light efficiency.

After the substrate 41 and the nitride layer are separated, as shown in FIG. 4D, an N-type electrode layer 46 is formed on the N-type nitride semiconductor layer 42 to manufacture an LED chip.

In the case of the light emitting device manufactured as described above, the light generated in the active layer is not totally reflected on the surface by the texturing effect of the surface, so that the overall light efficiency is improved.

As described so far, the second embodiment of the present invention includes all the effects of the first embodiment described above. Further, in addition to the effects of the first embodiment, a separate texturing process such as photoetching is performed by controlling the depth of implanted ions along a region of the N-type nitride semiconductor layer 42 in a predetermined pattern or irregularly. Without this, the texturing effect can be applied to the surface of the N-type nitride semiconductor layer 42 after the substrate is separated. Therefore, the light emitted from the active layer 43 is totally reflected from the surface to prevent the light from flowing back into the device. There is an effect of increasing the overall light efficiency.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

As described above, the present invention forms a separation layer by implanting ions and performs a heat treatment to separate the substrate and the nitride layer from the separation layer, thereby separating the substrate and the nitride layer using an excimer laser or the like to manufacture a thin film light emitting device. Compared with the prior art, it is possible to manufacture a thin film light emitting device without deterioration of ohmic characteristics in the N-type electrode region caused by thermal damage of the laser lift-off process at low cost, as well as physical stress generated at the interface. It is possible to minimize the damage to the device by.

In addition, the present invention has the effect of controlling the thickness of the N-type nitride semiconductor layer after the substrate separation by adjusting the depth of the separation layer is formed, and therefore, the thickness of the N-type nitride semiconductor layer can be adjusted thinly in the light emitting device In addition to the effect of facilitating heat dissipation, the thickness of the N-type nitride semiconductor layer in the active layer is reduced to reduce the amount of light absorbed, thereby improving the light efficiency of the entire light emitting device.

In addition, the present invention by controlling the depth of the ion implanted in a predetermined pattern or irregularly according to the region of the N-type nitride semiconductor layer, N after the substrate separation, without performing a separate texturing process such as photo etching The texturing effect can be provided on the surface of the nitride semiconductor layer, and therefore, light generated in the active layer is totally reflected from the surface and prevents the light from flowing back into the device, thereby increasing the light efficiency of the entire light emitting device.

Claims (12)

delete delete delete delete delete (a) forming a nitride layer on a predetermined substrate; (b) implanting predetermined ions into the nitride layer through the substrate to form a separation layer; And (c) heat-treating the substrate on which the nitride layer is formed to separate the substrate and the nitride layer from the separation layer, Step (b) is And the separation layer is formed at a non-uniform depth over the entire area of the nitride layer. (a) forming a nitride layer on a predetermined substrate; (b) implanting predetermined ions into the nitride layer through the substrate to form a separation layer; And (c) heat-treating the substrate on which the nitride layer is formed to separate the substrate and the nitride layer from the separation layer, Step (b) is The method of manufacturing a light emitting device, characterized in that to form a so that the separation layer has a curvature by adjusting the ion implantation conditions. (a) forming a nitride layer on a predetermined substrate; (b) implanting predetermined ions into the nitride layer through the substrate to form a separation layer; And (c) heat-treating the substrate on which the nitride layer is formed to separate the substrate and the nitride layer from the separation layer, Step (b) is The separation layer is formed to have an unevenness. (a) forming a nitride layer on a predetermined substrate; (b) implanting predetermined ions into the nitride layer through the substrate to form a separation layer; And (c) heat-treating the substrate on which the nitride layer is formed to separate the substrate and the nitride layer from the separation layer, Step (b) is At least one of an implantation amount, an implantation depth, and an implantation energy for implanting ions into the nitride layer according to a region into which the ions are implanted so that a texturing effect is formed on the surface of the nitride layer after the substrate is separated from the separation layer. The method of manufacturing a light emitting device, characterized in that to implant the ions into the nitride layer. The method according to any one of claims 6 to 9, (d) forming an electrode layer on the nitride layer. 10. The method according to any one of claims 6 to 9, wherein step (b) A method of manufacturing a light emitting device comprising implanting ions using a shadow mask or a photoresist. delete

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