KR100765385B1 - Light emitting device in which a plurality of light emitting cells are arranged - Google Patents

Abstract

The present invention provides a light emitting device comprising a light emitting cell block in which a plurality of light emitting cells are connected in parallel in a single chip, and a part of the light emitting cells is arranged in a forward direction based on one current flow and the other is arranged in a reverse direction. to provide. A plurality of light emitting cell blocks may be connected in series.

According to the present invention, by combining a plurality of light emitting cells in series and parallel on a single base substrate, the light emitting device can be miniaturized and can be driven even at a high voltage, and even if some light emitting cells are damaged, the driving of the light emitting device is not affected. It can emit light stably and has the advantage of improving the life.

Light Emitting Device, LED, AC Power, Forward, Reverse

Description

Light emitting device having an array of light emitting cells

1 is a conceptual circuit diagram for explaining a conventional light emitting device.

2 is a conceptual circuit diagram for explaining a light emitting device according to the present invention.

3 is a cross-sectional view of a unit light emitting cell according to the present invention;

4A to 4C are cross-sectional views illustrating a manufacturing process of a light emitting device according to the present invention.

5 is a plan view for explaining a light emitting device according to an embodiment of the present invention.

6 is a plan view for explaining a light emitting device according to another embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

10 light emitting cell 20 substrate

30: n-type semiconductor layer 40: active layer

50: p-type semiconductor layer 60: transparent electrode layer

70 wiring 100 light emitting cell

200: light emitting cell block 300: AC power

401, 402, 403, 404: connection terminal

500, 600: bonding pad

701, 702, 703, 704: connection pad

1000: light emitting element

The present invention relates to a light emitting device, and more particularly to a light emitting device in which a plurality of light emitting cells are arranged.

A light emitting device (LED) refers to a device that generates a small number of carriers (electrons or holes) injected using a p-n junction structure of a semiconductor and emits predetermined light by recombination thereof. Such light emitting devices are used as display devices and backlights, and active research is being conducted to apply them to general lighting applications. This is because the light emitting device consumes less power and has a longer life than conventional light bulbs or fluorescent lamps.

In general, the light emitting device could only be driven by a DC power supply due to diode characteristics. Therefore, the light emitting device using the conventional light emitting device is not only limited in use, but also includes a separate circuit such as a rectifier circuit in order to be used in the AC 220V power source currently used in the home. Accordingly, there is a problem that the circuit of the light emitting device becomes complicated and its manufacturing cost increases.

In order to solve this problem, researches on light emitting devices capable of driving a plurality of light emitting cells in series or in parallel with AC power are being actively conducted.

1 is a circuit diagram of a light emitting device that can be driven by a conventional alternating current (AC) power source.

Referring to the drawings, in the conventional light emitting device 10, the light emitting cell arrays 2a and 2b in which a plurality of cells 1 are connected in series are connected in parallel and connected to the AC power source 3. The two light emitting cell arrays 2a and 2b are connected to the power source 3 so as to have opposite polarities to each other, and the light emitting cell arrays 2a and 2b alternately operate in accordance with the direction of the current, so that the AC light source 3 is sufficient. Can be used.

Korean Patent Laid-Open Publication No. 2005-0052474 discloses a light emitting device in which a plurality of GaN-based light emitting devices are formed on an insulating substrate, and the plurality of light emitting devices are monolithically connected in series. The plurality of light emitting elements are divided into two sets of equal numbers, each array of light emitting elements is arranged in a zigzag shape, and the connection between the plurality of light emitting elements is formed by an air bridge wiring. Such a light emitting device has an advantage of operating at a high driving voltage.

However, in the light emitting device as described above, a plurality of light emitting cells in the light emitting cell array are connected in series. Therefore, when the performance of one light emitting cell is degraded in the light emitting cell array including a plurality of light emitting cells, there is a problem that the performance of the entire light emitting cell array is degraded due to the current applied to both ends.

In addition, there is a problem in that the entire operation is not performed due to a failure and damage of one of the light emitting cells constituting the light emitting cell array or a poor electrical connection.

The present invention is to solve the above problems, by connecting a plurality of light emitting cells in series and parallel on a single base substrate, the size of the light emitting device can be miniaturized and can be driven at a high voltage, and the light emitting device is damaged due to damage to some light emitting cells An object of the present invention is to provide a light emitting device in which a plurality of light emitting cells are arranged that can stably emit light without affecting driving and can improve driving life.

The present invention includes a light emitting cell block in which a plurality of light emitting cells are connected in parallel in a single chip to achieve the above object, a portion of the light emitting cells are arranged in a forward direction based on one current flow and the other are arranged in a reverse direction A light emitting device is provided. A plurality of light emitting cell blocks may be connected in series.

An anode of a portion of the light emitting cell of the light emitting cell block is connected to a first connection terminal and a cathode is connected to a second connection terminal, and the remaining cathode of the light emitting cell of the light emitting cell block is connected to the first connection terminal. And the anode is connected to the second connection terminal.

The number of light emitting cells in which an anode is connected to the first connection terminal and the cathode is connected to the second connection terminal, and the number of the remainder of the light emitting cells in which the cathode is connected to the first connection terminal and the anode is connected to the second connection terminal. It may be characterized by the same.

In addition, the plurality of light emitting cells may be connected through a predetermined wiring, and the predetermined wiring may be formed through a process such as a bridge process or a step cover.

Hereinafter, a light emitting device according to 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 will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you.

2 is a conceptual circuit diagram illustrating a light emitting device according to the present invention.

Referring to the drawings, the light emitting device 1000 includes light emitting cell blocks 200a and 200b in which a plurality of light emitting cells 100 are connected in parallel, and the light emitting cell blocks 200a and 200b are predetermined power nodes N10. , N20 are connected in series to the external AC power supply 300. Each of the light emitting cell blocks 200a and 200b includes at least one forward connected light emitting cell 100-1 and 100-2 and the other reversely connected light emitting cells 100-(n-1) and 100-n. Include. In this case, the forward and reverse directions refer to a current flow between the power nodes N10 and N20 to which the light emitting cell blocks 200a and 200b are connected, and are referred to from the first node N10 based on the first node N10. The direction when the current flows to the second node N20 is referred to as a forward direction, and the direction when the current flows from the second node N20 to the first node N10 is referred to as a reverse direction. That is, the anodes of at least one of the light emitting cells 100-1 and 100-2 connected in the forward direction of the first light emitting cell block 200a are commonly connected to the first connection terminal 401, and the cathode is connected to the second connection terminal ( 402 is commonly connected. The cathodes of the other light emitting cells 100-(n-1, 100-n) connected in the reverse direction of the first light emitting cell block 200a are commonly connected to the first connection terminal 401, and the anode is connected to the second connection terminal. 402 is commonly connected. In addition, the anodes of at least one of the light emitting cells 100-1 and 100-2 forward connected to the second light emitting cell block 200b are commonly connected to the third connection terminal 403, and the cathode is connected to the fourth connection terminal 404. ) Are commonly connected. The cathodes of the other light emitting cells 100-(n-1, 100-n) connected in the reverse direction of the second light emitting cell block 200b are commonly connected to the fourth connection terminal 404, and the anode is connected to the third connection terminal ( 403 in common.

As described above, in the light emitting device 1000 of the present invention, at least one forward connected light emitting cell 100-1 and 100-2 and the other reverse connected light emitting cells 100-(n-1) and 100-n are parallel to each other. A plurality of connected light emitting cell blocks 200a and 200b are connected in series.

Referring to the operation of the light emitting device 1000 according to the circuit diagram of FIG. 2, when a positive voltage is applied to the first node N10 and a negative voltage is applied to the second node N20. The light emitting cells 100-1 and 100-2 which are forwardly connected to the first light emitting cell block 200a and the second light emitting cell block 200b emit light. On the other hand, when a negative voltage is applied to the first node N10 and a positive voltage is applied to the second node N20, the first light emitting cell block 200a and the second light emitting cell block ( The reversely connected light emitting cells 100-(n-1) and 100-n of 200 b emit light. That is, even when the external AC power source 300 is applied to the light emitting device, since the plurality of light emitting cells of the first and second light emitting cell blocks 200a and 200b alternately emit light, the AC power source 300 may be sufficiently used. .

In the light emitting device 1000 of the present invention, the number of light emitting cells 100 constituting the light emitting device 1000 is very large according to a voltage, a current for driving the single light emitting cell 100, and an AC driving voltage applied to the light emitting device. It can vary. Although the number of forward and backward light emitting cells of the light emitting cell blocks 200a and 200b is not limited, the total number of light emitting cells backward connected to the forward connected light emitting cells is the same in order to minimize a change in brightness of the light emitting device 1000. It is preferable.

In addition, since the light emitting device 1000 according to the present invention includes a plurality of light emitting cells connected in parallel, even if a problem occurs in one light emitting cell, the light emitting device 1000 may stably emit light without affecting other light emitting cells. For example, in the conventional light emitting device as shown in FIG. 1, when some light emitting cells of the light emitting cell array connected in series in the forward direction are damaged or the connection between the light emitting cells is poor, when a current flows in the forward direction when an AC voltage is applied. There was a problem that did not work. On the other hand, the light emitting device of the present invention shown in Fig. 2 has a problem of damage to some light emitting cells because it emits light by a number of other forward connected light emitting cells even if a problem occurs in one forward connected light emitting cell of the first light emitting cell block. As a result, the performance of the light emitting device may be deteriorated or the phenomenon of not emitting light may be prevented. Therefore, stable light emitting characteristics of the light emitting device can be expected, and the lifespan can be prevented from being shortened due to poor connection and damage of some cells.

3 is a cross-sectional view of a unit light emitting cell 100 according to the present invention.

Referring to the drawings, the light emitting cell 100 includes a base substrate 20, an n-type semiconductor layer 30, an active layer 40, a p-type semiconductor layer 50 sequentially stacked on the base substrate 20, and the like. The transparent electrode layer 60 is included. In addition, the semiconductor device may further include an n-type electrode (not shown) formed on the exposed region of the n-type semiconductor layer 30, or a p-type electrode (not shown) formed on the transparent electrode layer 60. In this case, an n-type resistive connection film (not shown) and a p-type resistive connection film (not shown) may be further included on each of the lower n-type electrode and the lower p-type electrode, and the transparent electrode layer 60 may not be formed. have.

In the above, the base substrate 20 refers to a conventional wafer for fabricating a light emitting device. In this embodiment, the crystal growth substrate 20 made of sapphire is used. That is, the above-described multilayer structure is formed through epitaxial growth on the base substrate 20 of crystal growth.

A buffer layer (not shown) may be further included to reduce lattice mismatch between the base substrate 20 and subsequent layers when crystals are grown on the base substrate 20, and the buffer layer may include GaN, which is a semiconductor material.

The n-type semiconductor layer 30 is a layer in which electrons are generated, and is formed of an n-type compound semiconductor layer and an n-type cladding layer. At this time, the n-type compound semiconductor layer uses GaN doped with n-type impurities. The p-type semiconductor layer 50 is a layer in which pores are formed, and is formed of a p-type cladding layer and a p-type compound semiconductor layer. At this time, the p-type compound semiconductor layer uses AlGaN doped with p-type impurities.

The active layer 40 is a region where a predetermined band gap and a quantum well are made to recombine electrons and holes, and includes InGaN. In addition, the emission wavelength generated by the combination of electrons and holes is changed according to the type of material constituting the active layer 40. Therefore, it is preferable to adjust the semiconductor material contained in the active layer 40 according to the target wavelength.

The transparent electrode layer 60 serves to uniformly transfer the voltage input through the p-type electrode to the p-type semiconductor layer 50. In addition, the n-type electrode and the p-type electrode formed on the exposed region of the n-type semiconductor layer 30 and the transparent electrode layer 60 are for electrically connecting the light emitting cells 100 through metal wires. It can be formed in a laminated structure of Ti / Au.

As described above, the light emitting cell 100 of the present invention refers to a horizontal type of light emitting chip sequentially formed on the base substrate 20. In the present invention, one light emitting device is not manufactured using one light emitting chip. Instead, since a single light emitting device is formed using a plurality of light emitting chips, a conventional light emitting chip is referred to as a light emitting cell 100.

4A to 4C are cross-sectional views illustrating a manufacturing process of a light emitting device according to the present invention. The present invention provides a light emitting device capable of miniaturizing the light emitting device and simplifying the manufacturing process of the light emitting device by electrically connecting a plurality of light emitting cells on a single base substrate.

Referring to FIG. 4A, the n-type semiconductor layer 30, the active layer 40, and the p-type semiconductor layer 50 are sequentially formed on the base substrate 20. A buffer layer (not shown) may be further formed on the base substrate 20 to reduce lattice mismatch between the base substrate 20 and subsequent layers during crystal growth.

The above-described material layers include metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma chemical vapor deposition (PCVD), molecular beam growth (MBE), and molecular beam growth (MBE). It is formed through various deposition and growth methods including beam epitaxy) and hydride vapor phase epitaxy (HVPE).

Subsequently, as shown in FIG. 4B, a portion of the n-type semiconductor layer 30 is exposed by removing a portion of the p-type semiconductor layer 50 and the active layer 40 through a predetermined etching process, and the base substrate 20 is exposed. The predetermined region of the n-type semiconductor layer 30 exposed to form the plurality of light emitting cells 100 thereon is removed to expose the base substrate 20. In addition, the transparent electrode layer 60 is formed on the p-type semiconductor layer 50. This is not limited to the above, and may be variously changed for convenience of process. For example, first, a predetermined region of the base substrate 20 is exposed to form the transparent electrode layer 60 on the p-type semiconductor layer 50 and the plurality of light emitting cells 100 on the base substrate 20. After removing the transparent electrode layer 60, the p-type semiconductor layer 50, the active layer 40 and the n-type semiconductor layer 30, the predetermined transparent electrode layer 60, the p-type semiconductor layer 50 and the active layer 40 are removed. A portion of n) may be removed to expose a portion of the n-type semiconductor layer 30. At this time, a wet and dry etching process can be performed.

Referring to FIG. 4C, the adjacent light emitting cells 100 are electrically connected through a predetermined wiring forming process. For example, the exposed n-type semiconductor layer 30 of one light emitting cell and the transparent electrode layer 60 of another light emitting cell adjacent thereto are connected by wires. In the drawings, a cross-sectional view of a plurality of series-connected light emitting cells is shown. When the light emitting devices according to the present invention are connected in parallel and connected to the connection pads, they are electrically connected as described above. At this time, a conductive line 70 for electrically connecting adjacent light emitting cells is formed through a process such as a bridge process or a step cover.

The bridge process described above is also referred to as an air bridge process, by using a photo process between the chips to be connected to each other by using a photo process to form a photoresist pattern, and then forming a material such as metal on the first thin film by a method such as vacuum deposition, Again, a conductive material containing gold is applied to a predetermined thickness by a method such as electroplating, electroplating or metal deposition. Subsequently, when the photoresist pattern is removed with a solution such as a solvent, the lower portion of the conductive material is removed and only the bridge-shaped conductive material is formed in the space.

In addition, the step cover process uses a photo process between the chips to be connected to each other using a photo process, and develops, leaving only the portions to be connected to each other, and covering the other portions with a photoresist pattern, and on top of it by electroplating, electroless plating or metal deposition. Applying a conductive material containing a predetermined thickness. Subsequently, when the photoresist pattern is removed with a solution such as a solvent, all portions other than the conductive material are covered and only the portions covered with the conductive material remain to serve to electrically connect the chips to be connected.

As the wiring 70, all materials having conductivity as well as metal may be used.

In addition, the first bonding pad 500 is formed at one edge of the base substrate 20 and the second bonding pad 600 is formed at the other edge for electrical connection through a separate wire. The first and second bonding pads 500 and 600 use a metal having excellent electrical conductivity. It is formed by a screen printing method or a deposition process using a predetermined mask pattern.

The manufacturing of the light emitting device of the present invention described above is not limited thereto, and various processes and manufacturing methods may be changed or added according to the characteristics of the device and the convenience of the process. That is, the light emitting device may be manufactured by connecting not only the horizontal light emitting cells but also the vertical light emitting cells.

FIG. 5 is a plan view illustrating a light emitting device according to an exemplary embodiment of the present invention in which the light emitting device shown in FIG. 2 is actually implemented.

The present embodiment includes a plurality of light emitting cell blocks 200a, 200b, 200c, and 200d connected in series, and each light emitting cell block 200a, 200b, 200c, and 200d includes a plurality of light emitting cells 100 connected in parallel. . Referring to the drawings, 24 light emitting cells 100 are arranged in a 6 × 4 matrix form between two bonding pads 500 and 600, and connection pads 701, 702, and 703 and predetermined wirings are arranged. Four light emitting cell blocks 200a, 200b, 200c and 200d are connected in series through 70, and light emitting cells 100 of each light emitting cell block 200a, 200b, 200c and 200d are connected in parallel in a forward or reverse direction. have. At this time, the forward direction and the reverse direction refer to the current flow of the light emitting device, and the direction when the current flows from the first bonding pad 500 to the second bonding pad 600 based on the first bonding pad 500. It refers to the forward direction, and the direction when the current flows from the second bonding pad 600 to the first bonding pad 500 is referred to as the reverse direction.

The first light emitting cell block 200a is connected between the first light emitting pad 500 and the first connection pad 701 with three light emitting cells 100 connected in parallel in a forward direction through a predetermined wiring 70, and 3 connected in a reverse parallel manner. Light emitting cells 100. Similarly, the second light emitting cell block 200b is connected in parallel with the three light emitting cells 100 forward and parallel connected through the predetermined wiring 70 between the first connection pad 701 and the second connection pad 702. Three light emitting cells 100, and the third light emitting cell block 200c includes three light emitting cells connected in parallel between the second connection pads 702 and the third connection pads 703 through a predetermined wiring 70. It includes a light emitting cell 100 and three light emitting cells 100 connected in reverse parallel. In addition, the fourth light emitting cell block 200d is connected in parallel with the three light emitting cells 100 forward and parallel connected through the predetermined wiring 70 between the third connection pad 703 and the second bonding pad 600. Three light emitting cells 100 are included.

In the present exemplary embodiment, the adjacent light emitting cells 100 of the light emitting cell blocks 200a, 200b, 200c, and 200d have forward and reverse light emitting cells alternately connected in parallel, but the number and arrangement of the light emitting cells 100 are not limited thereto. It can be configured in various ways.

As described above, the plurality of light emitting cells 100 may be formed on the base substrate 20 and the first and second bonding pads may be formed on both sides of the substrate 20 to manufacture the light emitting device according to the present embodiment. The connection pads 701, 702, and 703 are formed between the light emitting cell blocks 200a, 200b, 200c, and 200d. In addition, a light emitting device may be fabricated by forming a predetermined wiring 70 connecting the light emitting cells 100 of the light emitting cell blocks 200a, 200b, 200c, and 200d in parallel through a predetermined bridge process or a step cover process. Can be.

In this embodiment, an external AC power is applied through the first and second bonding pads 500 and 600, and the plurality of light emitting cells of the first to fourth light emitting cell blocks 200a, 200b, 200c, and 200d may be provided. 100) can be used in AC power supply because they alternately emit light.

In addition, in the present embodiment, since a plurality of light emitting cells are connected in parallel, even if a problem occurs in some light emitting cells, the other light emitting cells can be stably emitted because the other light emitting cells can be applied without change. For example, even if one forward-connected light-emitting cell 100 of the first light-emitting cell block 200a is damaged, the light is emitted by the other forward-connected light-emitting cell 100. This phenomenon can be prevented from being degraded or failing to emit light. Therefore, stable light emitting characteristics of the light emitting device can be expected, and the lifespan can be prevented from being shortened due to poor connection and damage of some cells.

FIG. 6 is a conceptual diagram illustrating a light emitting device according to another embodiment of the present invention in which the light emitting device shown in FIG. 2 is actually implemented.

This embodiment includes a plurality of light emitting cell blocks 200 connected in series as in the above embodiment, and each of the light emitting cell blocks 200 includes a plurality of light emitting cells 100 connected in parallel, and only a separate connection pad is formed. It connects through a predetermined wiring 70 without.

Referring to the drawings, 30 light emitting cells 100 are arranged in a 6 × 5 matrix form between two bonding pads 500 and 600, and five light emitting cell blocks 200 are formed through predetermined wirings 70. The light emitting cells 100 of the light emitting cell blocks 200 are connected in series and connected in parallel in the forward or reverse directions. The wiring 70 is formed through a process such as a predetermined bridge process or a step cover. This has the advantage that it can take advantage of the area on the substrate 20 and efficiently utilized by connecting through the wiring 70 without the formation of a separate connection pad.

In this embodiment, an external AC power is applied through the first and second bonding pads 500 and 600, and the plurality of light emitting cells 100 of the five light emitting cell blocks 200 emit light alternately. It can be used even in power supply.

In addition, in the present embodiment, since a plurality of light emitting cells are connected in parallel, even if a problem occurs in some light emitting cells, the other light emitting cells can be stably emitted because the other light emitting cells can be applied without change. Therefore, stable light emitting characteristics of the light emitting device can be expected, and the lifespan can be prevented from being shortened due to poor connection and damage of some cells.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

The light emitting device of the present invention has an advantage that the light emitting device can be miniaturized by electrically connecting a plurality of light emitting cells on a single base substrate, and the manufacturing process of the light emitting device can be simplified. In addition, a plurality of light emitting cells can be connected to provide a light emitting device that can operate even at high voltage used in the home.

In addition, the light emitting device of the present invention can connect a plurality of light emitting cells by mixing in series and parallel, so that even if some light emitting cells are damaged, it can emit light stably without affecting the driving of the light emitting device, You can expect an improvement.

Claims (6)

A plurality of light emitting cells in a single chip includes a light emitting cell block connected in parallel through a wiring formed by a bridge process or a step cover process, And a part of the light emitting cells is arranged in the forward direction based on one current flow and the other is arranged in the reverse direction. The method according to claim 1, The light emitting device, characterized in that the plurality of light emitting cell blocks are connected in series. The method according to claim 1 or 2, An anode of a portion of the light emitting cell of the light emitting cell block is connected to a first connection terminal and a cathode is connected to a second connection terminal, and the remaining cathode of the light emitting cell of the light emitting cell block is connected to the first connection terminal. And the remaining anode is connected to the second connection terminal. The method according to claim 3, The number of light emitting cells in which an anode is connected to the first connection terminal and the cathode is connected to the second connection terminal, and the number of the remainder of the light emitting cells in which the cathode is connected to the first connection terminal and the anode is connected to the second connection terminal. The light emitting device characterized in that the same. delete delete

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