KR100809216B1 - Vertical structure semiconductor light emitting device manufacturing method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a vertical semiconductor light emitting device, and an embodiment of the present invention provides a method of preparing a conductive substrate having a light transmitting property, and a first conductive semiconductor layer, an active layer, and a second conductive type on the conductive substrate. Sequentially growing the semiconductor layer, forming a concave groove on the lower surface of the conductive substrate, forming a first electrode to fill the groove on the lower surface of the conductive substrate, and the second conductive semiconductor layer It provides a vertical structure semiconductor light emitting device manufacturing method comprising the step of forming a second electrode on the.

According to the present invention, it is possible to obtain a vertical structure semiconductor light emitting device manufacturing method in which the contact area between the electrode and the substrate is wider and the reflection efficiency in the electrode structure is increased, thereby improving electrostatic breakdown voltage and light extraction efficiency and reducing contact resistance.

Description

Method for manufacturing vertical structure semiconductor light emitting device {MENUFACTURING METHOD OF VERTICAL TYPE SEMICONDUCTOR LIGHT EMITTING DEVICE}

1 is a cross-sectional view showing a vertical structure semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 illustrates a reflection path of light at a first electrode portion of the vertical semiconductor light emitting device of FIG. 1.

3A to 3E are cross-sectional views illustrating a manufacturing process of a vertical semiconductor light emitting device according to another embodiment of the present invention.

4 is a cross-sectional view showing a vertical semiconductor light emitting device according to another embodiment of the present invention.

<Code Description of Main Parts of Drawing>

11,31,41: conductive substrate 12,32,42: first conductive semiconductor layer

13, 33, 43: active layer 14, 34, 44: second conductive semiconductor layer

15,35,45: highly reflective ohmic contact layer 16,36,46: second electrode

17,47: high reflective metal layer 18,38,48: first electrode

The present invention relates to a vertical semiconductor light emitting device and a method of manufacturing the same. More particularly, the electrode structure is improved to increase the contact area with the substrate and the reflection efficiency, thereby improving electrostatic breakdown voltage and light extraction efficiency and reducing contact resistance. The present invention relates to a vertical semiconductor light emitting device and a method of manufacturing the same.

BACKGROUND A light emitting diode (LED) is a semiconductor device capable of generating light of various colors based on recombination of electrons and holes at a junction portion of a p and n type semiconductor when current is applied thereto. These LEDs have a number of advantages over filament based light emitting devices, such as long life, low power, excellent initial driving characteristics, high vibration resistance, and high tolerance for repetitive power interruptions. In recent years, group III nitride semiconductors capable of emitting light in a blue short wavelength region have been in the spotlight.

The nitride single crystal constituting the light emitting device using the group III nitride semiconductor is generally formed on a specific single crystal growth substrate, such as a sapphire or SiC substrate. However, in the case of using an insulating substrate such as sapphire, the arrangement of electrodes is greatly limited. That is, in the conventional nitride semiconductor light emitting device, since the electrodes are generally arranged in the horizontal direction, the current flow becomes narrow. Due to such a narrow current flow, the forward voltage Vf of the light emitting device increases, resulting in a decrease in current efficiency, and also a problem of weakening of electrostatic discharge.

In order to solve the above problem, a semiconductor light emitting device having a vertical structure is required, and in this case, electrodes are formed on upper and lower surfaces of the vertical semiconductor light emitting device. However, the conventional electrode has a problem of reducing the light extraction efficiency of the light emitting device by reflecting the light emitted from the active layer. In addition, when the electrode area is reduced to solve the above problem, the area in contact with the conductive semiconductor layer or the support substrate is reduced, resulting in a large contact resistance.

Therefore, in a vertical semiconductor light emitting device, particularly a vertical nitride semiconductor light emitting device, it is necessary to reduce the contact resistance by increasing the contact area of the electrode, and furthermore, it is necessary to further enhance the electrostatic breakdown voltage by promoting the current dispersion effect in the lateral direction. There is also.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to improve the electrode structure of a light emitting device, thereby improving electrostatic breakdown voltage, light extraction efficiency, and reducing contact resistance, and a manufacturing method thereof. To provide.

In order to achieve the above technical problem, the present invention,

A concave groove is formed in the upper surface, and has a light-transmissive conductive substrate, a first conductive semiconductor layer formed on the lower surface of the substrate, an active layer formed on the lower surface of the first conductive semiconductor layer, and a second formed on the lower surface of the active layer. Provided is a vertical semiconductor light emitting device including a conductive semiconductor layer, a second electrode formed on a lower surface of the second conductive semiconductor layer, and a first electrode formed to fill the groove on the substrate.

In addition, in order to improve the external extraction efficiency of the light emitted from the active layer, it may further include a high reflective metal layer formed in the recessed portion of the region between the first electrode and the substrate. In this case, the highly reflective metal layer preferably includes at least one layer made of a material selected from the group consisting of Ag, Ni, Al, Ph, Pd, Ir, Ru, Mg, Zn, Pt, Au, and combinations thereof. .

The groove employed in the present invention extends the contact area between the first electrode and the conductive substrate to lower the contact resistance, and serves to strengthen the electrostatic breakdown voltage by distributing the current laterally. Preferably, the groove may have a hemispherical shape, but a structure suitable for reflecting the light traveling toward the first electrode to the outside or the other reflective layer may be adopted even though the groove is not exactly hemispherical. For example, a shape or an aspherical surface of a hollow sphere may be possible.

In addition, since the groove may be manufactured through a process such as wet etching, the recess of the groove may be formed along the crystal plane.

On the other hand, there are a plurality of grooves, the first electrode may be formed to fill the plurality of grooves, which is inefficient in terms of reflection of light. Therefore, a single groove is formed in the upper surface of the substrate, in this case, the width of the single groove is preferably 5 to 50㎛, the depth of 5 to 50㎛ in the range not to deviate from the width of the first electrode.

Preferably, the first conductive semiconductor layer may be a semiconductor layer doped with n-type impurities, and the second conductive semiconductor layer may be a semiconductor layer doped with p-type impurities.

The conductive substrate employed in the present invention may be made of a material selected from the group consisting of GaN, SiC, ZnO, Si, in this case, the first conductive semiconductor layer, the active layer and the second conductive semiconductor layer is nitride It is preferable.

The additional component may further include a highly reflective ohmic contact layer formed between the second conductive semiconductor layer and the second electrode. In this case, like the highly reflective metal layer, the highly reflective ohmic contact layer is at least made of a material selected from the group consisting of Ag, Ni, Al, Ph, Pd, Ir, Ru, Mg, Zn, Pt, Au and combinations thereof. It may comprise one layer.

Another aspect of the invention,

Providing a conductive substrate having a light transmissive property, sequentially growing a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on the conductive substrate, and forming a concave groove on a lower surface of the conductive substrate And forming a first electrode on the bottom surface of the conductive substrate so as to fill the groove, and forming a second electrode on the second conductive semiconductor layer. do.

Preferably, the forming of the first electrode includes a first step of depositing the first electrode to be formed on the side of the groove, and a second step of depositing to fill the remaining portion of the groove. can do.

In addition, preferably between the step of forming the groove and the step of forming the first electrode, further comprising the step of forming a high reflective metal layer in the recess of the groove, in this case, the high reflective metal layer is It may be made of a material as described above.

On the other hand, the step of forming the high reflective metal layer, may be to be deposited inclined so that the high reflective metal layer is formed on the side of the groove.

Finally, the groove may be formed by wet etching.

Accordingly, as described above, the groove may be formed in a hemispherical shape or the like, but may be irregularly formed along the crystal surface of the substrate.

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

1 is a cross-sectional view showing a vertical structure semiconductor light emitting device according to an embodiment of the present invention. FIG. 2 illustrates a reflection path of light at a first electrode portion of the vertical semiconductor light emitting device of FIG. 1. 3A to 3E are cross-sectional views illustrating a manufacturing process of a vertical semiconductor light emitting device according to another embodiment of the present invention. 4 is a cross-sectional view showing a vertical semiconductor light emitting device according to another embodiment of the present invention.

1, the vertical structure semiconductor light emitting device 10 according to the present embodiment,

The first conductive semiconductor layer 12, the active layer 13, the second conductive semiconductor layer 14, the highly reflective ohmic contact layer 15, and the second electrode formed sequentially on the conductive substrate 11 and the lower surface thereof. 16). In addition, a groove on which the first electrode 18 is positioned is formed on the conductive substrate 11, and a recess formed in the groove of the region between the first electrode 18 and the conductive substrate 11 is formed. It further comprises a highly reflective metal layer (17).

The conductive substrate 11 employed in the present embodiment also functions as a light transmitting portion in the vertical semiconductor light emitting device 10. Therefore, since the wing conductive substrate 11 preferably has a light transmittance, it may be made of a material selected from the group consisting of GaN, SiC, ZnO, and Si.

Meanwhile, the first conductive semiconductor layer 12 may be a semiconductor layer doped with n-type impurities, and the second conductive semiconductor layer 14 may be a semiconductor layer doped with p-type impurities.

The groove structure employed in the present embodiment increases the contact area between the first electrode 18 and the conductive substrate 11 to lower the contact resistance, and distributes the current laterally to strengthen the electrostatic withstand voltage. In addition, as shown in FIG. 2, when the groove has a hemispherical structure, the light emitted from the active layer 13 may be reflected to the outside or the highly reflective ohmic contact layer 15. Therefore, the light extraction efficiency of the vertical semiconductor light emitting device 10 can be improved. In this case, light extraction efficiency may be further improved by the high reflective metal layer 17, and the high reflective metal layer 17 may include Ag, Ni, Al, Ph, Pd, Ir, Ru, Mg, Zn, Pt, It may be formed of at least one layer made of a material selected from the group consisting of Au and combinations thereof.

1 and 2, in the present embodiment, the groove is adopted as a hemispherical shape, but as described above, a structure that easily reflects to the outside may be adopted and forms part of the hollow sphere. It can be shaped or aspheric.

On the other hand, the highly reflective ohmic contact layer 15 preferably has a reflectance of 70% or more, and forms an ohmic contact with the second conductive semiconductor layer 14. The highly reflective ohmic contact layer 15 may be formed of at least one layer made of a material selected from the group consisting of Ag, Ni, Al, Ph, Pd, Ir, Ru, Mg, Zn, Pt, Au, and combinations thereof. have. Preferably the highly reflective ohmic contact layer 15 is Ni / Ag, Zn / Ag, Ni / Al, Zn / Al, Pd / Ag, Pd / Al, Ir / Ag. It may be formed of Ir / Au, Pt / Ag, Pt / Al or Ni / Ag / Pt.

A manufacturing process for a vertical structure semiconductor light emitting device according to another embodiment of the present invention will be described with reference to FIGS. 3A to 3E.

First, as shown in FIG. 3A, the first conductive semiconductor layer 32, the active layer 33, and the second conductive semiconductor layer 34 are sequentially grown on the conductive substrate 31. The first and second conductivity-type semiconductor layers and the active layers formed on the conductive substrate 31 may be formed of nitrides as described above, and are known processes such as organometallic vapor deposition (MOCVD) and molecular beam growth methods. (MBE) and hydride vapor deposition (HVPE) and the like. Subsequently, a highly reflective ohmic contact layer 35 and a second electrode 36 are formed on the second conductive semiconductor layer 34. The second electrode 36 is formed by a deposition method or a sputtering process, which is a conventional metal layer growth method. Similarly, the highly reflective ohmic contact layer 35 may also be formed by a conventional deposition method or a sputtering process, and may be heat-treated at a temperature of about 400 ° C. to 900 ° C. to improve ohmic contact properties.

Subsequently, as shown in FIG. 3B, the photosensitive film pattern 40 is formed on the conductive substrate 31 except for the region where the groove is to be formed. In this embodiment, grooves are formed through an etching process in regions where the photoresist pattern 40 is not formed.

3C, a groove is formed in the conductive substrate 31 by a wet etching (WE) process. In this case, grooves are selectively formed only in the region where the photoresist pattern 40 is not present.

Meanwhile, referring to FIG. 3C, in the present embodiment, the cross-sectional shape of the groove is a part of the circle, that is, the curvature is a constant shape. In this case, as described above, the width of the single groove is the width of the first electrode. It is preferable that it is 5-50 micrometers in the range which does not deviate, and the depth is 5-50 micrometers. However, the shape of the groove in the present invention is not limited thereto, and may be in various forms such as polygons according to the shape to be etched.

Next, as shown in FIG. 3D, the first electrode 38 'is preferentially formed on the side surface of the groove concave through the inclined deposition process T, which is deposited in the inclined direction. Here, the gradient deposition process T may be a method of injecting gas in an inclined direction while tilting or leaving the light emitting device structure intact. In this case, although not shown, a process of depositing the highly reflective metal layer in the same manner may be performed first.

3E, the first electrode 38 is completed through the deposition process E to fill the empty portion of the groove. In this case, a variety of techniques may be used for depositing the first electrode 38. For example, Atmospheric Pressure Chemical Vapor Deposision (APCVD), Low Pressure Chemical Deposition (LPCVD), and Plasma Enhanced Chemical (PECVD) Vapor Deposition), metal thin film deposition using copper or high purity aluminum (Al 2 O 3), or the like may be used.

Finally, referring to FIG. 4, a vertical structure semiconductor light emitting device according to another embodiment of the present invention will be described.

As shown in FIG. 4, the vertical structure semiconductor light emitting device 40 according to the present embodiment has a first conductivity type semiconductor layer sequentially formed on the conductive substrate 41 and the lower surface thereof, as in the embodiment of FIG. 1. 42), an active layer 43, a second conductive semiconductor layer 44, a highly reflective ohmic contact layer 45, and a second electrode 46. In addition, a groove on which the first electrode 48 is positioned is formed on the conductive substrate 41, and a recess formed in the groove of the region between the first electrode 48 and the conductive substrate 41 is formed. It further comprises a high reflective metal layer (47).

In the present embodiment, the groove is plural and the first electrode 48 is formed to fill the plural grooves. In this case, as shown in the dotted line arrow, in the case of having a plurality of grooves as described above, the current dispersing effect which is one of the objects of the present invention can be further improved.

The above-described embodiments and the accompanying drawings are merely illustrative of preferred embodiments, and the present invention is intended to be limited by the appended claims. In addition, it will be apparent to those skilled in the art that the present invention may be substituted, modified, and changed in various forms without departing from the technical spirit of the present invention described in the claims.

As described above, according to the present invention, a vertical structure semiconductor light emitting device having a wider contact area between an electrode and a substrate, an improved reflection efficiency in an electrode structure, improved electrostatic breakdown voltage, light extraction efficiency, and reduced contact resistance, and a method of manufacturing the same You can get it.

Claims (21)

delete delete delete delete delete delete delete delete delete Providing a conductive substrate having light transparency; Sequentially growing a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on the conductive substrate; Forming a concave groove on a lower surface of the conductive substrate; Forming a first electrode on a bottom surface of the conductive substrate to fill the groove; And Forming a second electrode on the second conductive semiconductor layer; Vertical structure semiconductor light emitting device manufacturing method comprising a. The method of claim 10, The forming of the first electrode may include a first step of depositing the first electrode to be formed on a side surface of the groove, and a second step of depositing to fill the remaining portion of the groove. The vertical structure semiconductor light emitting device manufacturing method. The method of claim 10, And forming a highly reflective metal layer in the concave portion of the groove between the step of forming the groove and the step of forming the first electrode. The method of claim 12, The highly reflective metal layer includes at least one layer made of a material selected from the group consisting of Ag, Ni, Al, Ph, Pd, Ir, Ru, Mg, Zn, Pt, Au, and combinations thereof. Semiconductor light emitting device manufacturing method. The method of claim 12, The forming of the high reflective metal layer may include forming the high reflective metal layer inclined to be formed on the side of the groove. The method of claim 10, The step of forming the groove, the vertical structure semiconductor light emitting device manufacturing method, characterized in that by wet etching. The method of claim 10, The forming of the groove may include forming a single groove on the conductive substrate, wherein the width of the single groove is 5 to 50 μm and the depth is 5 to 50 μm. Manufacturing method. The method of claim 10, Wherein the first conductive semiconductor layer is a semiconductor layer doped with n-type impurities, and the second conductive semiconductor layer is a semiconductor layer doped with p-type impurities. The method of claim 10, The conductive substrate is a vertical structure semiconductor light emitting device manufacturing method, characterized in that made of a material selected from the group consisting of GaN, SiC, ZnO, Si. The method of claim 18, And the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer are nitrides. The method of claim 10, And further comprising forming a highly reflective ohmic contact layer on the second conductive semiconductor layer between growing the second conductive semiconductor layer and forming the second electrode. Structure semiconductor light emitting device manufacturing method. The method of claim 20, The highly reflective ohmic contact layer includes at least one layer made of a material selected from the group consisting of Ag, Ni, Al, Ph, Pd, Ir, Ru, Mg, Zn, Pt, Au, and combinations thereof. Vertical structure semiconductor light emitting device manufacturing method.

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