KR100433989B1 - Semiconductor LED device and manufacturing metheod thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor LED device. In particular, a pumping layer having excellent luminous efficiency by a heterojunction multilayer and an active layer made of a multilayer of homojunction capable of converting all received light to light having a desired wavelength due to less band gap. Since the light is generated in the AlGaInN pumping layer having a small amount of In, the light is incident on the active layer having a large amount of In, and the light is emitted to reduce the blue shift caused by the current. It is possible to emit light with two or more wavelengths in one LED device, so that light of various wavelengths can be obtained from one device, and the device is formed in a single continuous growth process, so the device has excellent reproducibility. This improves mass productivity, increases efficiency by not using fluorescent materials that reduce efficiency when forming white light, and mounts using bumps. The process is simple and can be implemented.

Description

Semiconductor LED device and its manufacturing method {Semiconductor LED device and manufacturing metheod

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting diode (LED) device and a method of manufacturing the same. Particularly, an AlGaInN-based LED uses a pumping layer having a high light conversion efficiency of a current to provide light having a desired wavelength. By pumping light into the emitting active layer, wavelength conversion is performed in the active layer to realize a monochromatic LED device wavelength-converted in one device, and by using a part of the pumping layer, two wavelengths are mixed in one device. The present invention relates to a semiconductor LED device capable of realizing white light.

In general, compound semiconductor devices include switching elements such as metal-semiconductor field effect transistors and high electron mobility transistors (HEMTs), and semiconductor lasers (LASER; light amplification by stimulated emission of radition). Photodiodes and PDs are used.

The laser is attracting attention as an effective transmission means for information communication because of its single wavelength and excellent linearity. Among them, the semiconductor laser has a smaller driving current, smaller size, and directly changes the intensity and frequency of light according to the change of current. It can be modulated, has a laser efficiency of 70% or more, and has a wide range of wavelengths. Therefore, it is widely used in office equipment such as laser printers, bar code readers, and optical communication devices.

1 is a cross-sectional view of an LED device according to the prior art, in which an insulating substrate is used and Al and In are not included in an AlGaInN LED device.

First, the buffer layer 11, the n-type GaN layer 12, the GaN (or InGaN) active layer 13, the p-type GaN layer 14, and the transparent electrode 15 are sequentially formed on the insulating transparent substrate 10. Stacked on one side of the transparent electrode 15, a metal p-type electrode 17 is formed, and the transparent electrode 15 on the other side of the substrate 10, the p-type GaN layer 14, and GaN Partial thicknesses of the active layer 13 and the n-type GaN layer 12 are removed, and an n-type electrode 16 made of metal is formed on the exposed n-type GaN layer 12.

The principle of the general compound semiconductor optical device as described above is that holes coming in through the p-type metal electrode and electrons coming in through the n-type metal electrode are combined in a single layer or multiple layers of active layer to provide light corresponding to the bandgap of the active layer material composition. It is a structure to emit. The light emitted from the active layer is mostly emitted to the upper and lower surfaces of the active layer. In the case of AlGaInN-based LEDs, this operation is possible because the upper layer of the active layer is transparent and the lower layer is transparent to the substrate.

In general, important characteristics such as LED output and wavelength are determined in the active layer, and the crystalline structure composition of the active layer becomes very important.

In the conventional AlGaInN-based LED structure, since only one wavelength of light is emitted from the active layer in a semiconductor device, there are problems such as using fluorescent materials or having different types of LEDs in order to obtain various colors.

In addition, a white LED which can replace a light bulb or a back light source of a display can be used for various purposes, but the white light LED must be formed in a package using a phosphor that emits complementary light of an LED emission wavelength. However, since the reliability of such a fluorescent material is lower than that of the LED device, there is another problem in that discoloration occurs or the luminous efficiency is lowered.

The present invention is to solve the above problems, an object of the present invention is to provide a pumping layer capable of high output inside the device to absorb the light generated from the pumping layer in the active layer and the absorbed light is recombined again in the active layer, The present invention provides a semiconductor LED device capable of efficiently obtaining light of a desired LED wavelength.

1 is a cross-sectional view of an LED device according to the prior art.

2 is a cross-sectional view of an LED device according to the present invention.

3a to 3e is a manufacturing process of the LED device according to the present invention.

4 is a mounting cross-sectional view of the LED device of FIG.

<Description of Symbols for Main Parts of Drawings>

10,20,30: substrate 11,21,31: buffer layer

12,22,24,32 n-type AlGaInN layer 13,23,33 active layer

14,26,36 p-type AlGaInN layer 15 transparent electrode

16,29,39: n-type electrode 17,27,37: p-type electrode

25,35 pumping layer 28,43 insulating film

41: lower wiring 42: silicon substrate

44: p-type wiring 45,47: bump

46 n-type wiring 50 semiconductor LED device

Features of the semiconductor LED device according to the present invention for achieving the above object,

In the AlGaInN-based LED device,

A first conductive type Al _x1 Ga _y1 In _z1 N layer (x1 + y1 + z1 = 1) formed on an insulating transparent substrate,

An active layer pattern, a pumping layer pattern, a second conductive AlGaInN layer pattern, and a second conductive electrode, which are sequentially formed on one side of the first conductive type Al _x1 Ga _y1 In _z1 N layer, are provided. a single layer or multiple layers of more than homozygous Al _x Ga _y in _z N / Al _x1 Ga _y1 in _z1 N material, and wherein the pump layer is a single layer or multiple layers of the heterojunction Al _a Ga _b in _c N / Al _a1 Ga _b1 In _c1 N material, at least one pumping layer is provided together with the active layer to form a vertically integrated LED device, but the band gap of Al _x Ga _y In _z N of the active layer is the band of Al _a Ga _b In _c N of the pumping layer. Less gaps,

The first conductive type electrode is provided on the other side of the first conductive type Al _x1 Ga _y1 In _z1 N layer.

In addition, the substrate is formed of alumina, sapphire or quartz, and the sidewalls of the active layer pattern, the pumping layer pattern, and the second conductive AlGaInN layer pattern have an inclination angle of 10 to 89 ° so that the light reflected from the sidewall is To be reflected toward the side.

In addition, the semiconductor LED device is mounted, but the second conductive wiring formed on one side of the silicon substrate is connected to the second conductive electrode of the LED via bumps, and the insulating film is formed on the other side of the silicon substrate. The first conductive type wiring is connected to the first conductive type wiring of the LED device via a bump.

In addition, a feature of the method for manufacturing a semiconductor LED device according to the present invention,

A multi-layered or single-layered active layer in which a first conductive type Al _x1 Ga _y1 In _z1 N layer, an Al _x Ga _y In _z N / Al _x1 Ga _y1 In _z1 N material of the same conductivity type is repeatedly laminated on an insulating transparent material substrate, A step of sequentially forming a first conductive type AlGaInN layer, a pumping layer in which _a heterojunction Al _a Ga _b In _c N / Al _a1 Ga _b1 In _c1 N material is repeatedly laminated, and a second conductive AlGaInN layer,

Forming a plurality of patterns by sequentially etching the second conductive AlGaInN layer to the active layer and exposing one side of the first conductive Al _x1 Ga _y1 In _z1 N layer;

Forming a second conductive electrode on the second conductive AlGaInN layer;

Forming an insulating film on side surfaces of the patterns;

And forming a first conductive electrode in contact with the exposed first conductive Al _x1 Ga _y1 In _z1 N layer.

In addition, the first conductive Al _x1 Ga _y1 In _z1 N layer, the active layer, the pumping layer and the second conductive AlGaInN layer are formed by one of MOCVD, MBE, and VPA, and the second conductive AlGaInN layer to the active layer. The etching process is performed by the inclined etching process so that the sidewalls have an inclination angle so that the light reflected from the sidewalls is reflected by the substrate.

Hereinafter, a semiconductor LED device and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

Looking at the basic principle of the present invention.

First, the general AlGaInN-based optical device has a characteristic that the efficiency decreases as the amount of In in the active layer increases. Usually, the wavelength of InGaN active layer containing about 35% of In is about 470 nm. In this case, the output is about 3 to 5 mW depending on the structure of the device. On the other hand, in the case of the active layer having a wavelength of 380 nm containing about 5% of In or 430 nm containing about 22% of In, the output easily exceeds about 10mW even in the same structure. This is because, as the amount of In in the active layer increases, the quality of the crystal weakens and the efficiency rapidly decreases. In addition, when the amount of In increases, the wavelength is shifted to the shorter side in the process of converting light into a current by injecting a current into the active layer, thereby increasing efficiency.

The new structure of the present invention utilizes the advantages of a high quality pumping layer having a low In composition and an active layer having a high In composition, in particular, an active layer that converts absorption of light into light, rather than recombination emission by current. Therefore, the wavelength of light to be obtained can be obtained from the same conductive type, for example, the n-n active layer, not in the conventional p-n structure.

This principle makes it easy to convert 470nm (blue), 525nm (green), and 635nm (red) light, which is not efficient, by using a pumping layer that emits light of high efficiency, for example, wavelengths of 380 to 430 nm. can do.

Using this principle, it is possible to obtain light with more than one wavelength from a single LED device, and to obtain a new color wavelength by proper mixing of these two or more wavelengths. For example, the deep blue (~ 450 nm) wavelength of light generated by the pumping layer is absorbed by the active layer, and when the yellow (590 nm) light is complementary to this color, the thickness of the active layer and the number of layers of the active layer are controlled. White light can be obtained by adjusting the amount of absorption and transmission in the active layer of blue (~ 450 nm) wavelength light.

Alternatively, the light of the pumping layer may be partially emitted and mixed with the light of the active layer to obtain two wavelengths of light.

Since the multi-wavelength LED does not use fluorescent materials, the reliability of the device is innovatively improved, and the epi wafer obtained in one epitaxial growth process can be manufactured by applying the existing blue LED process, thereby simplifying the process. Uniformity of device characteristics is excellent, and mass productivity is improved.

The semiconductor LED device vertically arranges an active layer that determines the wavelength and output of the LED and a pumping layer that supplies energy to the active layer so that all the light generated from the pumping layer is absorbed in the active layer.

2 is a cross-sectional view of a semiconductor LED device according to the present invention, in which an n-n type homojunction active layer and a pumping layer are vertically integrated.

First, a buffer layer 21 and an n-type Al _x1 Ga _y1 In _z1 N layer (22, x1 + y1 + z1 = 1) are formed on an insulating transparent substrate 20 such as alumina, sapphire, or quartz. On the n-type Al _x1 Ga _y1 In _z1 N layer 22, a multi-layered active layer 23 pattern in which Al _x Ga _y In _z N / Al _x1 Ga _y1 In _z1 N materials were repeatedly laminated, and an n-type AlGaInN layer ( 24) a pattern, _a multiply pumped layer 25 pattern in which Al _a Ga _b In _c N / Al _a1 Ga _b1 In _{c 1} N materials are repeatedly stacked, a p-type AlGaInN layer 26 pattern, and a p-type electrode 27 ) Patterns are stacked sequentially. Wherein the active layer 23 pattern, the n-type AlGaInN layer 24 pattern, the multiply pumped layer 25 pattern in which the Al _a Ga _b In _c N / Al _a1 Ga _b1 In _c1 N material is repeatedly laminated, p The sidewall of the patterned AlGaInN layer 26 has an inclination angle of 10 to 89 ° so that the light emitted from the side surface is reflected from the etched side and is easily inclined toward the substrate, and the n-type AlGaInN layer 24 pattern May be removed as needed.

In addition, a transparent insulating film 28 is formed on the sidewalls of the active layer 23 to the p-type electrode 27 pattern for side protection, and n is in contact with the n-type Al _x1 Ga _y1 In _z1 N layer 22. The type electrode 29 is formed.

The p-type and n-type electrodes 27 and 29 are formed of an opaque metal material to reflect light to the substrate 20.

The active layer 23 and the pumping layer 25 are layers in which two layers having different compositions having different band gaps are repeatedly stacked in FIG. 2 for convenience, and the active layer 23 has a composition Two layers of nn or pp type Al _x Ga _y In _z N / Al _x1 Ga _y1 In _z1 N of different conductivity type but with the same conductivity type, x + y + z = 1 and x1 + y1 + z1 = 1 satisfy sikimyeo, active role in the Al _x Ga _y in _z N layer of the band gap _{(Eg (Al x Ga y in} z N)) a barrier layer Al _x1 Ga _y1 in _z1 N of the band gap (Eg (Al _x1 Ga _y1 in _z1 N) than small, and the pumping layer 25 pn structure of Al _a Ga _b in _c N / Al _a1 Ga _b1 in _c1 N material for this is repeated layer, Al to the pumping role _a Ga _b in _c N The band gap Eg (Al _a Ga _b In _c N) of the layer is larger than the band gap Eg (Al _x Ga _y In _z N) of the active layer 23, and the amount of In is also small.

The operating principle of the semiconductor LED device formed as described above is that holes entering through the p-type AlGaInN layer 26 pattern are limited to the pumping layer 25 by currents supplied from two electrodes, and n-type Al _x1 Ga _y1 In Electrons entering through the _z1 N layer 22 are also limited to the pumping layer 25 to emit light of energy corresponding to the bandgap (Eg (pumping layer)) of the pumping layer 25 while electrons and holes are combined. Light emitted downward from the pumping layer 25 is absorbed into the active layer 23 as it is, and light emitted from the upper portion of the pumping layer 25 is reflected from the p-type electrode 27 and absorbed into the active layer 23.

Then, the absorbed light is converted into electrons and holes in the active layer 23 and is limited by the barrier layer of the active layer 23, and then recombined in the active layer 23 to combine the band gap Eg (active layer) of the active layer 33. It will emit light corresponding to)). This light is the smallest light in the LED structure and can be emitted entirely through the substrate without being absorbed in any layer anymore. The n-p types may be interchanged.

3A to 3E are manufacturing process diagrams of a semiconductor LED device according to the present invention.

First, the buffer layer 31 and the n-type Al _x1 Ga _y1 In _z1 N layer 32 and the same conductivity type Al _x Ga _y In _z N / are formed on an insulating light-transmitting substrate 30 such as alumina, sapphire or quartz. Al _x1 Ga _y1 in _z1 N material is repeated, an active layer 33 of the layer multi-layer, n-type AlGaInN layer 34, it is repeated layer Al _a Ga _b in _c N / Al _a1 Ga _b1 in _c1 N material of the opposite conductivity type The pumping layer 35 and the p-type AlGaInN layer 36 are sequentially formed. The layers are referred to as Metal-Organic Chemical Vapor Deposition (hereinafter referred to as MOCVD), molecular beam epitaxy (hereinafter referred to as MBE) or vapor phase epitaxy (hereinafter referred to as VPA). And the like can be used. (See FIG. 3A).

Then, patterns are formed by sequentially etching the p-type AlGaInN layer 36 to the active layer 33 using a patterning mask (not shown). In this case, a part thickness of the n-type Al _x1 Ga _y1 In _z1 N layer 32 is etched. At this time, the sidewalls are formed to have an inclined angle by using the inclination etching from the p-type AlGaInN layer 36 to the active layer 33 so that the light reflected from the sidewall is reflected toward the substrate. (See Figure 3b).

After that, a p-type electrode 37 reflecting light is formed on the p-type AlGaInN layer 36 (see FIG. 3C), and an insulating film 38 for lateral protection of patterns is formed on the entire surface of the structure. This is then patterned to expose the n-type Al _x1 Ga _y1 In _z1 N layer 32. At this time, the p-type electrode 37 is also exposed for subsequent conductive line connection. (See FIG. 3D).

An n-type electrode 39 is then formed in contact with the exposed n-type Al _x1 Ga _y1 In _z1 N layer 32. (See Figure 3E).

In the above, the n-p types may be interchanged.

4 is a cross-sectional view of the semiconductor LED device of FIG. 2 mounted on a silicon substrate, wherein an insulating film 43 is formed on an upper surface of the silicon substrate 42, and one side of the insulating film 43 is removed and exposed. The p-type wiring 44 is formed on the silicon substrate 42 in ohmic contact, and the n-type wiring 46 is formed on the other side of the insulating film 43. The p-type electrode and the n-type electrode are connected to the wirings 44 and 46 through the bumps 45 and 47, respectively, and an ohmic contact lower wiring for applying a substrate voltage to the lower surface of the silicon substrate 42 ( 41) is formed. In the mounting array, only the n-type wiring 44 is wire bonded and the lower wiring is directly connected to a voltage, thereby reducing the number of wire bonding.

As described above, the semiconductor LED device according to the present invention is a pumping layer having excellent luminous efficiency by a heterojunction multilayer, and a multilayer of homojunction that can convert all received light into light having a desired wavelength due to less band gap. Since the active layer is formed, light is generated in an AlGaInN pumping layer having a small amount of In, and the light is incident on the active layer having a large amount of In, thereby emitting light to reduce blue shift due to current. Improve efficiency, and can emit light with two or more wavelengths in one LED device, so that light of various wavelengths can be obtained from one device, and the device is reproducible because the device is formed by a continuous growth process. This has the advantage that the productivity is improved, and the efficiency is increased by not using a fluorescent material that decreases the efficiency when forming white light. All.

In addition, by increasing the absorption rate in the active layer by adjusting the thickness and the number of the active layer, it is possible to implement a short-wavelength monochromatic LED in which the pumping layer is all converted to the wavelength of the active layer, and it is possible to mount using bumps, thereby simplifying the mounting process.

Claims (9)

In the AlGaInN-based LED device, A first conductive type Al _x1 Ga _y1 In _z1 N layer (x1 + y1 + z1 = 1) formed on an insulating transparent substrate, An active layer pattern, a pumping layer pattern, a second conductive AlGaInN layer pattern, and a second conductive electrode, which are sequentially formed on one side of the first conductive type Al _x1 Ga _y1 In _z1 N layer, are provided. a single layer or multiple layers of more than homozygous Al _x Ga _y in _z N / Al _x1 Ga _y1 in _z1 N material, and wherein the pump layer is a single layer or multiple layers of the heterojunction Al _a Ga _b in _c N / Al _a1 Ga _b1 In _c1 N material, the pumping layer is provided with at least one of the active layer and vertically integrated to form an LED device, wherein the band gap of Al _x Ga _y In _z N of the active layer is Al _a Ga _b In of the pumping layer. less than the bandgap of _c N, And a first conductive electrode formed on the other side of the first conductive Al _x1 Ga _y1 In _z1 N layer, And sidewalls of the active layer pattern, the pumping layer pattern, and the second conductive AlGaInN layer pattern have an inclination angle of 10 ° to 89 ° so that light reflected from the sidewall is reflected toward the substrate. The method of claim 1, The first and second conductivity type semiconductor LED device, characterized in that the n and p type. The method of claim 1, And the substrate is one material arbitrarily selected from the group consisting of alumina, sapphire and quartz. delete The semiconductor LED device of claim 1 is mounted, and the second conductive wiring formed on one side of the silicon substrate is connected to the second conductive electrode of the LED via bumps, and the insulating film is formed on the other side of the silicon substrate. The first conductive type wiring is connected to the first conductive type wiring of the LED element via an array of semiconductor LED elements. A multi-layered or single-layered active layer in which a first conductive type Al _x1 Ga _y1 In _z1 N layer, an Al _x Ga _y In _z N / Al _x1 Ga _y1 In _z1 N material of the same conductivity type is repeatedly laminated on an insulating transparent material substrate, A step of sequentially forming a first conductive type AlGaInN layer, a pumping layer in which _a heterojunction Al _a Ga _b In _c N / Al _a1 Ga _b1 In _c1 N material is repeatedly laminated, and a second conductive AlGaInN layer, Each pattern is formed by sequentially etching the second conductive AlGaInN layer to the active layer, and the sidewalls of the active layer pattern, the pumping layer pattern, and the second conductive AlGaInN layer pattern are 10 ° to Forming an inclination angle for reflecting light of 89 ° toward the substrate; Exposing one side of the first conductive type Al _x1 Ga _y1 In _z1 N layer, Forming a second conductive electrode on the second conductive AlGaInN layer; Forming an insulating film on side surfaces of the patterns; And forming a first conductive electrode in contact with the exposed first conductive Al _x1 Ga _y1 In _z1 N layer. The method of claim 6, And the first and second conductivity types are n and p types, respectively. The method of claim 6, The first conductive Al _x1 Ga _y1 In _z1 N layer, the active layer, the pumping layer and the second conductive AlGaInN layer is a method of manufacturing a semiconductor LED device, characterized in that formed by one of the MOCVD, MBE and VPA method. The method of claim 6, And etching the second conductive AlGaInN layer from the second conductive type AlGaInN layer to the active layer in an inclined etching process such that the light reflected from the sidewall is reflected to the substrate.