KR20120046930A - Manufacturing method of semiconductor light emitting device using patterned substrate - Google Patents

Abstract

PURPOSE: A method for manufacturing a semiconductor light emitting device using a patterned substrate is provided to reduce the amount of laser which enters an active layer in lift off since a passage is changed by diffracting, scattering, refracting the laser absorbed into a sapphire substrate interface. CONSTITUTION: A convex portion(113) of a photonic crystal pattern is formed on the front side of a semiconductor substrate(110). An n-type semiconductor layer(115), an active layer(120), and a p-type semiconductor layer(125) are formed on the front side of the semiconductor substrate. A P electrode(135) is formed on the p-type semiconductor layer. A conductive substrate(140) is attached to the P electrode. An N electrode(145) is formed on the n-type semiconductor layer.

Description

Manufacturing method of semiconductor light emitting device using patterned substrate {Manufacturing method of semiconductor light emitting device using patterned substrate}

The present invention relates to a method for manufacturing a semiconductor light emitting device, and more particularly, to a method for manufacturing a vertical structure semiconductor light emitting device.

A semiconductor light emitting device such as a light emitting diode (LED) is one of solid state electronic devices that convert current into light, and typically includes an active layer of a semiconductor material interposed between a p-type semiconductor layer and an n-type semiconductor layer. When a driving current is applied across the p-type semiconductor layer and the n-type semiconductor layer in the semiconductor light emitting device, electrons and holes are injected into the active layer from the p-type semiconductor layer and the n-type semiconductor layer. The injected electrons and holes recombine in the active layer to generate light.

In general, the semiconductor light emitting device is a nitride group III-V group having an Al _x In _y Ga _(1-xy) N composition formula, where 0≤x≤1, 0≤y≤1, 0≤x + y≤1 Although it is manufactured with a semiconductor compound, it becomes a device which can produce short wavelength light (ultraviolet light-green light), especially blue light. However, since the nitride compound semiconductor is manufactured by using an insulating substrate such as a sapphire substrate or a silicon carbide (SiC) substrate that satisfies the lattice matching condition for crystal growth, the p-type semiconductor layer and n Two electrodes connected to the semiconductor semiconductor layer have a planar structure in which they are arranged almost horizontally on the upper surface of the light emitting structure.

However, when the n-type electrode and the p-type electrode are arranged almost horizontally on the upper surface of the light emitting structure, the light emitting area is reduced, the luminance is decreased, and current spreading is not smooth, causing reliability problems vulnerable to electrostatic discharge (ESD). . In addition, there is a problem that the yield is reduced by reducing the number of chips on the same wafer. In addition, there is a limit in reducing the chip size, and furthermore, since the sapphire substrate has poor thermal conductivity, heat generated during high-power driving is not sufficiently discharged, thereby limiting device performance.

In order to solve this problem, a laser lift off method for separating the sapphire substrate and the nitride compound semiconductor layer part by decomposing the interface between the sapphire substrate and the nitride compound compound semiconductor layer using the high-density energy of the high power laser. To manufacture a semiconductor light emitting device having a vertical structure.

1 is a vertical structure fabricated by forming a nitride compound semiconductor layer composed of an n-type semiconductor layer, an active layer and a p-type semiconductor layer on a sapphire substrate, and then separating the sapphire substrate by a laser lift-off method and attaching a support conductive substrate. It is sectional drawing which shows a semiconductor light emitting element.

Referring to FIG. 1, a conventional vertical structure semiconductor light emitting device 10 includes a metal layer 35, a p-type semiconductor layer 25, an active layer 20, and an n-type semiconductor layer 15 on a conductive substrate 40. The n-type electrode 45 is formed on the n-type semiconductor layer 15 upper surface. When a driving current is applied across the p-type semiconductor layer 25 and the n-type semiconductor layer 15, electrons and holes are injected into the active layer 20 from the p-type semiconductor layer 25 and the n-type semiconductor layer 15. . The injected electrons and holes recombine in the active layer 20 to generate light.

2 is a cross-sectional view for explaining a laser lift-off method of the method of manufacturing the vertical structure semiconductor light emitting device.

First, an n-type semiconductor layer 15, an active layer 20, and a p-type semiconductor layer 25 are grown sequentially on the semiconductor substrate 5 to form a light emitting structure, and then a metal layer on the p-type semiconductor layer 25. (35) is formed. Next, the conductive substrate 40 is attached on the metal layer 35. The conductive substrate 40 is an element included in the final semiconductor light emitting device 10 and serves as a support for supporting the light emitting structure.

Next, the semiconductor substrate 5 is removed by a laser lift-off process. At this time, the KrF laser beam LB is irradiated from the rear surface side of the semiconductor substrate 5 to separate the interface between the semiconductor substrate 5 and the n-type semiconductor layer 15. However, in the related art, since the laser beam LB breaks through the n-type semiconductor layer 15 to the active layer 20, there is a problem in that luminous efficiency is lowered when the device is manufactured.

The problem to be solved by the present invention is to provide a method for manufacturing a semiconductor light emitting device excellent in the luminous efficiency is prevented from destroying the active layer during the laser lift-off process.

In the semiconductor light emitting device manufacturing method according to the present invention for solving the above problems, a convex portion of the nanometer (nm) class photonic crystal pattern is formed on at least one of the front and rear surfaces of the semiconductor substrate. The n-type semiconductor layer, the active layer and the p-type semiconductor layer are sequentially grown on the entire surface of the semiconductor substrate, and then a p-type electrode is formed on the p-type semiconductor layer, and a conductive substrate is attached on the p-type electrode. . The laser is incident on the rear surface of the semiconductor substrate to remove the semiconductor substrate from the resultant to which the conductive substrate is attached, but the amount of incident light into the active layer is reduced by diffraction, scattering, or refraction using the photonic crystal pattern. Then, an n-type electrode is formed on the n-type semiconductor layer.

The planar shape of the nanometer-class photonic crystal pattern may be triangular, square or circular, and the shape of the nanometer-class photonic crystal pattern may be pyramidal, rectangular parallelepiped, or hemispherical. Such nanometer-class photonic crystal pattern may be arranged in one or two dimensions.

Forming an n-type or undoped semiconductor layer before forming the n-type semiconductor layer on the front surface of the semiconductor substrate, and removing the n-type or undoped semiconductor layer after removing the semiconductor substrate. It may further include.

In the present invention, the laser absorbed into the compound semiconductor layer and the sapphire substrate interface during the laser lift-off process is changed by diffraction, scattering, or refraction using a photonic crystal pattern to change the amount of laser incident to the active layer during laser lift-off compared to the conventional method. Can be reduced. As a result, the destruction of the active layer can be reduced, thereby increasing the efficiency of semiconductor light emitting devices such as vertical LEDs.

1 is a cross-sectional view showing a vertical structure semiconductor light emitting device according to the prior art.
2 is a cross-sectional view for explaining a laser lift-off method of a method of manufacturing a vertical structure semiconductor light emitting device according to the prior art.
Figure 3 is a cross-sectional view for each process showing an embodiment of a method for manufacturing a semiconductor light emitting device according to the present invention.
Figure 4 is a cross-sectional view for each process showing another embodiment of a method for manufacturing a semiconductor light emitting device according to the present invention.
5 is a cross-sectional view illustrating processes according to another embodiment of the method of manufacturing a semiconductor light emitting device according to the present invention.
6 is a cross-sectional view illustrating processes according to another embodiment of the method of manufacturing a semiconductor light emitting device according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments make the disclosure of the present invention complete, and the scope of the invention to those skilled in the art. It is provided for complete information. In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated or exaggerated for clarity.

Figure 3 is a cross-sectional view for each process showing an embodiment of a method for manufacturing a semiconductor light emitting device according to the present invention. Here, a conventional vertical structure nitride III-V semiconductor compound semiconductor light emitting device manufacturing method is manufactured in plural using a predetermined wafer, Figure 3 shows a method of manufacturing only one light emitting device for convenience of description Doing.

First, as shown in FIG. 3A, a convex portion 113 having a nanometer photonic crystal pattern is formed on the front surface of the semiconductor substrate 110. The semiconductor substrate 110 is a substrate suitable for growing a nitride semiconductor single crystal, and may be formed of SiC, zinc oxide (ZnO), gallium nitride (GaN), and aluminum nitride (AlN) in addition to sapphire. have.

Lithography and dry etching processes may be used to form the convex portions 113 of the nanometer-class photonic crystal pattern on the semiconductor substrate 110. Or FIB milling process. The ion beam used in the FIB has a Gaussian distribution of the beam distribution. If the irradiation position of the beam is properly adjusted, a continuous pattern with a pitch similar to that of the beam can be produced to form a pattern without forming an etch mask. Can be.

The convex portion 113 may be formed at a specific period and size capable of diffracting, scattering, or refracting the laser used in consideration of the wavelength of the laser to be used in the laser lift-off process. The nanometer scale means that these periods and sizes have units of hundreds of nm. The planar shape (viewed above) of the convex portion 113 may be triangular, square or circular. The three-dimensional shape may be pyramidal, cuboid or hemispherical. The convex portion 113 may be formed in a one-dimensional line array or a two-dimensional surface array.

The n-type semiconductor layer 115, the active layer 120, and the p-type semiconductor layer 125 are sequentially grown on the entire surface of the semiconductor substrate 110 to form a light emitting structure, and then p is formed on the p-type semiconductor layer 125. The type electrode 135 is formed. The n-type semiconductor layer 115 is formed with the concave portion 116 of the nanometer-class photonic crystal pattern formed by the uneven structure of the semiconductor substrate 110.

The n-type semiconductor layer 115, the active layer 120, and the p-type semiconductor layer 125 have an In _X Al _Y Ga _1-XY N composition formula (where 0 ≦ X, 0 ≦ Y, and X + Y ≦ 1). It may be made of a semiconductor material having. More specifically, the n-type semiconductor layer 115 may be formed of a GaN layer or a GaN / AlGaN layer doped with n-type impurities, for example, Si, Ge, Sn, Te or C, etc. Is used, and preferably Si is mainly used. The p-type semiconductor layer 125 may be formed of a GaN layer or a GaN / AlGaN layer doped with p-type impurities. For example, Mg, Zn, Be, or the like may be used as the p-type impurity. Mainly uses Mg. The active layer 120 is a layer for generating and emitting light, and is generally formed by forming a multi-quantum well with an InGaN layer as a well and a GaN layer as a wall layer. The active layer 120 may be composed of one quantum well layer or a double hetero structure. The semiconductor layer 114, the n-type semiconductor layer 115, the active layer 120, and the p-type semiconductor layer 125 are formed through a deposition process such as MOCVD, MBE, or HVPE.

The p-type electrode 135 plays a role of reflecting light generated in the active layer 120 as well as an ohmic contact function with the conductive substrate 140 and a function of the electrode. The p-type electrode 135 may be formed of one or more multilayer films including a material selected from the group consisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, and Au. Considering the role of reflection, Ni / Ag, Zn / Ag, Ni / Al, Zn / Al, Pd / Ag, Pd / Al, Ir / Ag. It is preferable to form by film combinations, such as Ir / Au, Pt / Ag, Pt / Al, Ni / Ag / Pt.

Next, as shown in FIG. 3B, the conductive substrate 140 is attached to the p-type electrode 135. The conductive substrate 140 is an element included in the final semiconductor light emitting device 100 and serves as a support for supporting the light emitting structure. In particular, when the semiconductor substrate 110 is removed by the laser lift-off process, the conductive substrate 140 may be attached to the light emitting structure having a relatively thin thickness.

The conductive substrate 140 may be made of a material selected from the group consisting of Si, Cu, Ni, Au, W, and Ti. The conductive substrate 140 may be formed on the p-type electrode 135 by a process such as plating, deposition, and sputtering, depending on the selected material. Can be formed directly. Here, in the embodiment, the example in which the conductive substrate 140 is attached through a wafer bonding process is not limited thereto. A bonding metal layer made of a eutectic alloy mainly containing Au and Sn is formed on the p-type electrode 135. It may further be deposited and attached by means of pressurization / heating.

Next, the semiconductor substrate 110 is removed. In this case, a laser lift-off process is used. A laser, for example, a KrF laser (LB) having a wavelength of 248 nm is irradiated onto the back surface of the semiconductor substrate 110 to follow an interface between the n-type semiconductor layer 115 and the semiconductor substrate 110. The semiconductor substrate 110 is separated. At this time, the convex portion 113 of the photonic crystal pattern changes the path toward the semiconductor substrate 110 by diffracting, scattering or refracting the laser LB. As a result, the amount of laser incident on the active layer 120 is significantly reduced than before. Therefore, the semiconductor substrate 110 can be separated without destroying the active layer 120.

Next, referring to FIG. 3C, an n-type electrode 145 is formed on the n-type semiconductor layer 115 having a concave portion 116 having a reverse phase with the convex portion 113 of the photonic crystal pattern on the surface. . After forming the n-type electrode 145, a passivation film (not shown) is formed using an insulating dielectric for side protection. Of course, the passivation film is first formed, and then the n-type electrode 145 is formed.

As described above, according to the method of manufacturing a semiconductor light emitting device, the amount of laser entering the active layer during laser lift-off can be reduced by using the photonic crystal pattern formed on the semiconductor substrate. As a result, the destruction of the active layer can be reduced, thereby increasing the efficiency of semiconductor light emitting devices such as vertical LEDs.

In addition, in order to solve the problem of decrease in external quantum efficiency, in the conventional vertical structure semiconductor light emitting device, the surface of the n-type semiconductor layer is etched using KOH solution to form roughness to form the n-type electrode. The rough surface thus formed is very easy to extract light by lowering the incident angle of photons incident into the air from the nitride compound semiconductor layer below the critical angle. According to the manufacturing method of the present invention, the surface roughness is caused by the formation of the concave portion having the reverse phase with the convex portion of the photonic crystal pattern on the surface of the n-type semiconductor layer. Accordingly, light extraction is improved without wet etching using a KOH solution.

FIG. 4 is a cross-sectional view illustrating processes according to another embodiment of the method of manufacturing a semiconductor light emitting device according to the present invention, and the following description will focus on differences from FIG. 3.

As shown in FIG. 4A, a convex portion 113 having a nanometer photonic crystal pattern is formed on the entire surface of the semiconductor substrate 110. Then, the semiconductor layer 114 is formed thereon. The semiconductor layer 114 is formed of an n-type or undoped semiconductor layer. The semiconductor layer 114 may be formed of, for example, AlN / GaN. It may function as a buffer layer for lattice matching between the semiconductor substrate 110 and the n-type semiconductor layer 115 to be formed in a subsequent process. A separate buffer layer may be formed between the semiconductor substrate 110 and the semiconductor layer 114. According to the deposition method, the semiconductor layer 114 is formed with the recessed portion 116 of the nanometer-class photonic crystal pattern by the uneven structure of the semiconductor substrate 110.

Next, an n-type semiconductor layer 115, an active layer 120, and a p-type semiconductor layer 125 are grown on the semiconductor layer 114 to form a light emitting structure, and then on the p-type semiconductor layer 125. The p-type electrode 135 is formed.

Subsequently, as shown in FIG. 4B, after attaching the conductive substrate 140 to the p-type electrode 135, the semiconductor substrate 110 is irradiated with KrF laser LB on the entire surface of the semiconductor substrate 110. ). At this time, the convex portion 113 of the photonic crystal pattern redirects the laser LB toward the semiconductor substrate 110, so that the amount of laser incident to the active layer 120 is significantly reduced. Accordingly, the semiconductor substrate 110 may be separated without destroying the active layer 120.

Referring to FIG. 4C, the semiconductor light emitting device 100 ′ is manufactured by forming an n-type electrode 145 on a semiconductor layer 114 exposed to the outside by removing the semiconductor substrate 110. The semiconductor light emitting device 100 ′ includes a semiconductor layer 114 unlike the semiconductor light emitting device 100 described with reference to FIG. 3.

5 is a cross-sectional view illustrating processes according to another embodiment of the method of manufacturing a semiconductor light emitting device according to the present invention. This is a modification of the embodiment shown and described in Fig. 4, and Figs. 5 (a) and 5 (b) correspond to Figs. 4 (a) and 4 (b), respectively. The difference from FIG. 4 is that the semiconductor layer 114 exposed after the semiconductor substrate 110 is removed using a wet cleaning solution or the like is exposed, and then the n-type semiconductor layer 115 is exposed and an n-type electrode 145 is formed thereon to form a semiconductor light emitting device. To make (100 ").

Unlike the semiconductor light emitting device 100 described with reference to FIG. 3, the semiconductor light emitting device 100 ″ has no recess of a nanometer-type photonic crystal pattern on the surface of the n-type semiconductor layer 115. For example, the surface of the n-type semiconductor layer 115 may be etched using a KOH solution to generate roughness, and then the n-type electrode 145 may be formed.

FIG. 6 is a cross-sectional view illustrating a method of manufacturing a semiconductor light emitting device according to an exemplary embodiment of the present invention, hereinafter, focusing on differences from FIG. 3.

First, as shown in FIG. 6A, a convex portion 113 having a nanometer photonic crystal pattern is formed on the rear surface of the semiconductor substrate 110. The n-type semiconductor layer 115, the active layer 120, and the p-type semiconductor layer 125 are sequentially grown on the entire surface of the semiconductor substrate 110 to form a light emitting structure, and then p is formed on the p-type semiconductor layer 125. The type electrode 135 is formed.

Next, as shown in FIG. 6B, the conductive substrate 140 is attached to the p-type electrode 135, and the semiconductor substrate 110 is irradiated with a laser beam LB on the rear surface of the semiconductor substrate 110. Separate. At this time, the convex portion 113 of the photonic crystal pattern changes the path toward the semiconductor substrate 110 by diffracting, scattering or refracting the laser LB. As a result, the amount of laser incident on the active layer 120 is significantly reduced than before. Accordingly, the semiconductor substrate 110 may be separated without destroying the active layer 120.

Next, referring to FIG. 6C, by forming the n-type electrode 145 on the n-type semiconductor layer 115, a semiconductor light emitting device 100 ″ having the same structure as described with reference to FIG. 5 is manufactured.

As described above, the convex portion 113 of the photonic crystal pattern may be formed on the front surface or the rear surface of the semiconductor substrate 110 or both the front surface and the rear surface. To reduce it.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the technology to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

Claims (5)

Forming a convex portion of a nanometer-type photonic crystal pattern on at least one of a front surface and a rear surface of a semiconductor substrate;
Sequentially growing an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on the front surface of the semiconductor substrate;
Forming a p-type electrode on the p-type semiconductor layer;
Attaching a conductive substrate on the p-type electrode;
Injecting a laser into the back surface of the semiconductor substrate to remove the semiconductor substrate from the resultant on which the conductive substrate is attached, but diffracting, scattering or refraction the laser using the photonic crystal pattern to reduce the amount of incident light into the active layer; And
A method of manufacturing a semiconductor light emitting device comprising forming an n-type electrode on the n-type semiconductor layer. The method of claim 1, wherein the planar shape of the nanometer-class photonic crystal pattern is triangular, square, or circular. The method of claim 1, wherein the nanometer photonic crystal pattern has a pyramidal shape, a cuboid shape, or a hemispherical shape. The method of claim 1, wherein the nanometer photonic crystal patterns are arranged in one or two dimensions. The method of claim 1, further comprising: forming an n-type or undoped semiconductor layer on the front surface of the semiconductor substrate, and removing the n-type or undoped semiconductor layer after removing the semiconductor substrate. The method of manufacturing a semiconductor light emitting device, characterized in that it further comprises the step of removing the layer.

Images