KR100531801B1 - Light emitting diode lighting apparatus and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a light emitting diode lighting device and a method of manufacturing the same, when using a conventional light emitting diode (LED) as an illumination device such as a backlight, the lighting device as a package type LED due to size, light uniformity, cost problems It is difficult to implement, and when used directly attached to the printed circuit board in the form of a chip requires a precise wire bonding process, there was a problem that the yield and reliability deteriorate. In addition, even when the LED is bonded to the stem after the recently proposed silicon sub-mount, the wire bonding process is essential for the external power supply, so the yield and reliability are low. There was a problem that process equipment was needed. In view of the above problems, the present invention can attach a light emitting diode (LED) to a chip state, and form a groove to prevent light interference between adjacent LEDs while condensing the emitted light from the LED to the front, and the groove Light emitting diode lighting apparatus and a fabrication method of manufacturing a light emitting diode illuminating device in which a structure in which an LED is attached to a sub-mount in which an electrode extends from the inside to the outside is arranged upside down on a transparent substrate on which electrode wiring is formed, and then bonded by flip chip bonding By providing a method, it is possible to greatly increase the process time, cost and reliability, it is possible to prevent the scattering of the emitted light and to reduce the mutual optical interference to significantly increase the light efficiency.

Description

LIGHT EMITTING DIODE LIGHTING APPARATUS AND MANUFACTURING METHOD THEREOF

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode lighting apparatus and a method of manufacturing the same, and in particular, in a lighting apparatus consisting of a light emitting diode array, the light emitting diode is transparent so that the light emitting surface thereof is directed toward the substrate side after bonding the light emitting diode to a submount having grooves formed with electrodes The present invention relates to a light emitting diode illuminating device capable of flip chip bonding on a substrate, and to easily bonding.

In general, the light emitting device has been used as a display device using simple light emission, but recently, the possibility of a light source having various wavelengths and energy has been studied. Currently, active light emitting devices are classified into laser diodes (LDs) and light emitting diodes (LEDs). LDs are widely used as light sources in the optical communication field. In addition, the application area is gradually becoming diverse, such as being applied to backlight devices of lighting devices or LCD displays.

In particular, LEDs can operate at a relatively low voltage, but have a low heat generation and a long lifespan due to high energy efficiency.As a result, technologies that can provide white light with high brightness, which have been difficult to implement in the past, have been developed one after another. Is expected to be the dream technology to replace the lighting device.

Research is being actively conducted to arrange such LEDs in an array and use them as backlights of display devices that are difficult to emit light. In particular, it is expected to be a backlight light source that can replace the cold cathode tube (CCFL) used in thin film transistor (TFT) LCD, which is rapidly increasing in use.

TFT LCD is a device that realizes color by changing the transmittance of light by changing the direction of liquid crystal according to the voltage applied between a pair of transparent electrodes facing in parallel. Large area is possible, and it is gradually replacing CRT (Chathod Ray Tube). However, since the TFT LCD does not emit light by itself unlike a plasma display panel, an electroluminescent display device, or a CRT, a backlight unit for supplying light to a display device is required. The backlight unit is a surface light source generator that allows the light emitted from the light emitting unit to be spread evenly throughout the panel.

1 is a cross-sectional view showing a structure of a general backlight unit 10, and is made of a multi-layer as shown in the drawing, and receives light from the light source 8 pre-emitting from the side of the backlight unit to emit light and spread the light evenly. The LCD panel 1 is supplied to the upper portion of the backlight unit 10.

The backlight unit 10 is formed on one side of the light guide plate 6 and the light guide plate 6 that receives the light provided from the light source 8 and scatters the light received by the glass material formed therein to reflect the light. The reflective plate 7, the diffuser plate 5 positioned at the other side of the light guide plate 6 to scatter the light provided from the light guide plate 6, and the light diffused through the diffuser plate 7 can be spread evenly. It consists of a vertical / horizontal prism 4,3 arranged at right angles and a protective layer 2 disposed on the vertical / horizontal prism 4,3.

The light source 8 generally uses a cold cathode tube (CCFL) that generates a small amount of heat and provides even light emission. Also used. By arranging LEDs as a line light source, manufacturing cost, driving power, and power control unit size are greatly reduced, and the brightness of the display unit is also comparable to that of the CCFL light source due to the provision of increasingly high brightness LEDs.

FIG. 2 is a cross-sectional view illustrating a structure of a general LED used as a backlight light source, and a buffer layer 22 and an n-contact layer are sequentially formed on a substrate 21 such as sapphire or n-GaAs, as shown. (23), the active layer 24 and the p-contact layer 25 are continuously deposited by chemical vapor deposition, and patterned to expose the n-contact layer 23 by a photolithography process and a wet / dry etching method. . Thereafter, the insulating layer 26 is deposited on the formed structure and patterned to expose the p-contact layer 25 on the structure and a portion of the n-contact layer 23 exposed in the above process for electrical connection. Then, a metal is formed on the exposed p-contact layer 25 and n-contact layer 23 after patterning to form a p-electrode 27 and an n-electrode 28.

The light emitting diode configured as described above emits light by applying a voltage between the p-electrode 27 and the n-electrode 28, and when a voltage is applied, holes are formed into the p-electrode 27 and the n-electrode 28. And electrons are injected and holes and electrons are recombined in the active layer 24 to emit light to the outside.

The LED formed in the chip state may be directly applied on a substrate, and may be attached to various packages (epoxy molding, can-type package). However, when formed in the epoxy molding type, the light efficiency is lowered by the epoxy, it is difficult to obtain an even light emission effect, and it is difficult to dissipate the generated heat to the outside. And because of its large size, compact placement is difficult. When used in a can-type package (TO-can), the size of the package is large, which makes it difficult and dense to form a line light source. Therefore, a method of forming an electrode pattern on a printed circuit board and directly attaching an LED chip to the pattern, and then connecting the electrode by wire bonding is mainly used. It takes a long process time, generates bad defects, and has low reliability. The technique powers the LEDs, resulting in lower yields and higher costs. In addition, the printed circuit board is difficult to effectively dissipate heat generated when the densely arranged LED devices are driven, which can lower the life of the device and change its characteristics.

Therefore, in recent years, after the LED sub-mount is formed by using a semiconductor process, LEDs are connected to the sub-mounts, and sub-mounts with LEDs are arranged and used on a substrate on which electrode wiring is formed. However, the general sub-mount forms an electrode layer connected to the LED electrode on the silicon substrate to arrange the LED on the electrode layer, and connects the electrode wiring formed on the substrate using the extended electrode layer as a wire bonding pad and a wire bonding technique. Let's do it. In this case, a wider wire bonding pad can be used than in the case of directly attaching the LED chip on the substrate, thereby facilitating the process.

However, even in the case of using a conventional sub-mount, a low yield wire bonding should be used to connect to an external power source, so that the defect rate is high, the process takes a long time, and the overall reliability is also greatly lowered. In particular, wire bonding for a long structure must be performed to form a linear light source, and thus a specially manufactured wire bonding equipment is required.

As described above, when the LEDs are arranged and used as a lighting device such as a backlight, it is difficult to implement the lighting device as a packaged LED due to size, light uniformity, and cost, and a printed circuit board in the form of a chip. In the case of using directly attached to the phase, a precise wire bonding process is required, and thus there is a problem that the yield and reliability deteriorate. In addition, even when the LED is bonded to the stem after the recently proposed silicon sub-mount, the wire bonding process is essential for the external power supply, so the yield and reliability are low. There was a problem that process equipment was needed.

In view of the above problems, the present invention can attach a light emitting diode (LED) in a chip state, and form a groove to prevent optical interference between adjacent LEDs while condensing the emitted light from the LED to the front. Structures with LEDs attached to the sub-mounts with electrodes extending from the inside to the outside of the grooves can be placed upside down on a transparent substrate with electrode wiring, and then bonded by flip chip bonding, resulting in low yield, reliability and low cost. It is an object of the present invention to provide a light emitting diode lighting apparatus and a method of manufacturing the same, which can increase process time, cost, and reliability by preventing a high wire bonding process, prevent scattering of emitted light, and greatly increase light efficiency by reducing mutual light interference.

In the present invention for achieving the above object, in the light emitting diode lighting apparatus in which a plurality of light emitting diodes are arranged to serve as a line light source or a surface light source, grooves of a light emitting diode height or more are formed in a region to which the light emitting diodes are bonded. A silicon sub-mount in which electrodes extending from the groove to the outside are formed; A light emitting diode connected to the electrodes formed on the grooves of the sub-mounts by using a solder layer; The electrode of the sub-mount, to which the light emitting diode is connected, comprises a transparent substrate that is flip-chip bonded with electrode wiring formed on a surface thereof.

In addition, the present invention provides a method of forming a groove in which a light emitting diode is to be disposed by bulk etching a portion of a silicon substrate using a mask layer; Forming an electrode layer extending from the inside of the groove to the outside of the groove; Cutting the silicon substrate structure by a groove to form a sub-mount, and then bonding a light emitting diode to an electrode layer in the groove; Preparing a transparent substrate on which an electrode wiring is formed on a surface through a separate process; And disposing a sub-mount having an electrode extending on the substrate to flip-chip bond the electrode on the sub-mount to the electrode wiring on the transparent substrate.

DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiments of the present invention implemented as described above will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view showing a structure of an embodiment of the present invention, as shown in the sub-mount 30 is attached to the light emitting diode (LED) 36 on the electrode wiring 41 formed on the transparent substrate 40 It is an LED lighting device that can be aligned or surface-emitting. Note that the emission direction of light in the structure is toward the transparent substrate 40.

A heat sink for dissipating heat generated by the driving of the light emitting diodes 36 may be further formed on the upper portion of the illustrated structure, that is, the substrate portion of the sub-mount 30. The heat dissipation efficiency is also high on its own since there is no surface area for heat dissipation.

The electrode wiring 41 may greatly improve light emission efficiency when using transparent electrodes (Indume Tin Oxide (ITO, ZnO, etc.)), but may be generally opaque metal electrodes if electrode patterning is possible to avoid light emission paths. Can also be used to reduce costs.

The sub-mount 30 supporting the LED 36 is a core structure of the present invention. The silicon substrate 31 is bulk-etched to form grooves having a predetermined depth in a portion where the LED 36 is to be disposed. do. As shown, since the sub-mount 30 is mounted upside down after mounting the LED 36 on the transparent substrate 40, the thickness of the silicon substrate 31 is greater than or equal to the depth required for mounting the LED 36. The depth of the groove should also be higher than the height of the LED 36.

The groove is etched to have a predetermined angle during bulk etching by the crystal structure of the silicon substrate, and the electrode layer 34 can be easily formed as shown by this characteristic. The electrode layer 34 extends from the inside of the groove formed in the silicon substrate 31 to the top of the silicon substrate 31 where the groove is not formed (out of the mounting position of the LED 36). The extended portion is then used as a flip chip bonding pad for powering the LED 36. The sub-mount 30 having the grooves as described above can achieve a wide variety of effects. First, flip chip bonding as shown in the drawing can be achieved, and heat generated during operation of the LED 36 can be rapidly generated in the air. The silicon thickness of the LED 36 mounting portion can be reduced to disperse. In addition, light interference between adjacent LEDs 36 may be prevented and the light emission direction may be focused to the front, and the light emitting efficiency may be greatly improved when a reflective layer is further formed on the groove.

The thickness of the silicon substrate 31 in the groove region can be lowered to a physically possible limit, and even in this case, the silicon substrate 31 surrounding the groove has sufficient physical strength, so that the overall physical strength can be maintained.

Although the present invention can be achieved with the above structure alone, as described above, the reflective layer 32 may be formed on the silicon substrate 31 to more effectively concentrate the light emission of the LED 36 in the front direction. In general, since the reflective layer 32 uses a metal such as Ag or Al having a high reflection coefficient, a transparent insulating layer 33 is further formed on the reflective layer 32 to prevent electrical contact with the electrode layer 34. It is preferable to form. However, if the electrode layer 34 is properly patterned while being made of a material having a high reflectance, the reflective layer insulated from the electrode may be made in one metal process.

4A to 4E are sectional views illustrating a manufacturing process of an embodiment of the present invention, and the manufacturing process for the sub-mount 30 and the LED 36 bonding process of the configuration of the embodiment of the present invention described with reference to FIG. 3 as shown. Will be shown.

First, as shown in FIG. 4A, a mask layer is formed on the silicon substrate 31 or a mask pattern necessary for bulk etching the LED mounting region is formed using the silicon substrate 31 on which the mask layer is already formed.

Next, as shown in FIG. 4B, a portion of the silicon substrate 31 is wet etched using the mask pattern. Through such a bulk etching process, grooves having a predetermined angle are formed in each area where the LED is to be disposed, and the depth thereof is deeper than the height of the LED to be mounted thereafter, so as to reduce the light leaking out to the side as much as possible. Inverted to enable flip chip bonding. After removing the mask layer, a metal reflective layer 32 having a high reflection coefficient and an insulating layer 33 for insulation are sequentially formed on the entire upper surface of the formed structure. The metal reflective layer 32 is formed of a highly reflective metal, such as Ag or Al, by a deposition method, a lift-off method, or the like. However, as described above, it may be carried out in a batch process in the electrode forming process to be formed later. As the insulating layer 33, a general insulating film used in a semiconductor process such as a silicon nitride film may be used. However, it is preferable to use a transparent insulator for high reflection effect.

Next, as shown in FIG. 4C, an electrode layer 34 is formed on the formed insulating layer 33 to apply a voltage to the LED to be subsequently mounted by metal etching or lift-off. It extends from the lower end of the groove to the upper region of the silicon substrate 31 where the groove is not formed. The electrode layer 34 should have a solder pad (inside the groove) for mounting the LED and a flip chip bonding pad (outside the groove) for external power connection.

Next, as shown in FIG. 4D, a solder layer 35 for LED bonding is formed on the electrode layer 34 inside the formed groove, and cut into a sub-mount. The solder layer 35 uses a material that can electrically connect LEDs such as Au-Sn, In, Pb, and Pb-Sn.

Next, as shown in FIG. 4E, the LED 36 is disposed on the chip-cut submount, and then heat-treated to bond the LED 36 to the submount.

Thereafter, the formed LED 36 and the sub-mount 30 are inverted up and down to attach to the transparent substrate on which the electrode wiring is formed in various alignment methods to implement the lighting apparatus. The LED 36 may be unified in the emission color of the same wavelength, it may be appropriately arranged in three primary colors of light, such as red, green, blue to form a color.

5 shows the transparent substrate 40 and the electrode wiring 41 on which the formed submount structure 30 is to be mounted.

As illustrated, the electrode wiring 41 is formed by forming and patterning a transparent electrode material on the entire surface of the transparent substrate 40 such as a glass substrate or a quartz substrate. In this embodiment, although the electrode wiring 41 for driving all LEDs in parallel is formed, the wiring for driving the individual LEDs or the LEDs in a predetermined combination may be formed. A solder layer 42 for bonding is formed on a portion of the submount connection of the upper part of the electrode wiring 41. According to the shape of the electrode wiring 41, the sub-mount to which the LED is bonded can be attached in various alignment methods, thereby making it possible to form lighting devices for various uses.

Thereafter, as shown in FIG. 3, the sub-mount 30 having the LED mounted on the solder layer 42 is vertically inverted and then heat-treated to perform flip chip bonding.

As described above, the present invention can improve the efficiency by focusing the light emitting direction of the LED to the light emitting surface in the illumination device consisting of LED array, can suppress the interference with the adjacent LED, and most of all the process using a flip chip bonding method It can increase ease of use and reduce costs. The lighting device formed in the above manner may be utilized in various applications such as a display backlight, simple lighting, a traffic light, and a display light of a vehicle.

As described above, the LED lighting apparatus of the present invention and a method of manufacturing the same can attach a light emitting diode (LED) in a chip state, and collect light emitted from the LED to the front to prevent optical interference between adjacent LEDs. By forming a groove, the structure in which the LED is attached to the sub-mount in which the electrode extends from the groove to the outside is disposed upside down on the transparent substrate on which the electrode wiring is formed, and then bonded by flip chip bonding. In addition, the process time, cost and reliability can be greatly increased, and the light efficiency can be greatly increased by preventing scattering of emitted light and reducing mutual light interference.

1 is a cross-sectional view showing a backlight structure of a thin film transistor LCD.

2 is a cross-sectional view of a general light emitting diode.

3 is a light emitting diode backlight light source according to an embodiment of the present invention.

Figures 4a to 4e is a cross-sectional view showing the manufacturing process of an embodiment of the present invention.

5 is a plan view showing a transparent substrate and the electrode wiring according to an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

30: submount 31: substrate

32: reflective layer 33: insulating layer

34: electrode layer 35: solder layer

36: light emitting diode 40: transparent substrate

41: electrode wiring 42: substrate solder layer

Claims (7)

In a light emitting diode lighting apparatus in which a plurality of light emitting diodes are disposed to serve as a line light source or a surface light source, grooves having a height greater than the light emitting diodes are formed in a region to which the light emitting diodes are bonded, and silicon having electrodes extending from the grooves to the outside. A submount; A light emitting diode connected to the electrodes formed on the grooves of the sub-mounts by using a solder layer; And a transparent substrate on which the electrodes of the sub-mount to which the light emitting diodes are connected are flip chip bonded to the electrode wirings formed on the surface thereof. The light emitting diode illuminating device according to claim 1, wherein the transparent substrate is a substrate made of a transparent material including a glass substrate or a quartz substrate. The light emitting diode illuminating device according to claim 1, wherein the electrode wiring formed on the surface of the transparent substrate is a transparent electrode. The light emitting diode illuminating device according to claim 1, further comprising a reflective layer having high reflectance of light on the silicon substrate forming the sub-mount. Bulk etching a portion of the silicon substrate using a mask layer to form a groove in which the light emitting diode is to be disposed; Forming an electrode layer extending from the inside of the groove to the outside of the groove; Cutting the silicon substrate structure by a groove to form a sub-mount, and then bonding a light emitting diode to an electrode layer in the groove; Preparing a transparent substrate on which an electrode wiring is formed on a surface through a separate process; And disposing a sub-mount having an electrode extending on the substrate, flip-bonding the electrode on the sub-mount to the electrode wiring on the transparent substrate. . 6. The method of claim 5, wherein forming an electrode on the silicon substrate comprises: forming a highly reflective metal reflective layer on the grooved silicon substrate and forming a transparent insulating layer thereon; And forming the electrode layer on the upper part of the formed insulating layer. The method of claim 5, wherein the forming of the electrode on the silicon substrate comprises forming a metal layer having high reflectivity on the silicon substrate on which the groove is formed, and simultaneously forming an electrode pattern and a reflective layer. Method of manufacturing diode lighting device.