TWI505512B - System and method for fabricating light emitting diode (led) dice with wavelength conversion layers - Google Patents

Description

System and method for fabricating light emitting diode dies having a wavelength conversion layer

The present invention is a continuation of U.S. Patent Application Serial No. 13/229,824, filed on Sep. 12, 2011, which is incorporated herein by reference.

The present invention relates to light-emitting diode dies, and more particularly to luminescent diode dies having a wavelength converting layer, and a system for fabricating light emitting diode dies having a wavelength converting layer and methods therefor.

Light emitting diode (LED) dice are developed to produce white light. In order to produce white light, a blue light emitting diode die can be used in combination with a wavelength converting layer, such as a phosphor layer formed on a die (by a blue LED). The electromagnetic radiation emitted by the crystal grains excites atoms of the wavelength conversion layer, which converts some electromagnetic radiation in the blue wavelength spectral region to the yellow wavelength spectral region (yellow wavelength spectral region). The ratio of blue to yellow is controlled by the composition and geometry of the wavelength conversion layer so that the output of the light emitting diode appears white light.

A method for forming a wavelength converting layer in a light emitting diode die is to fabricate the wavelength converting layer into a separate member which is then attached to the die. For example, the wavelength conversion layer can be a piece of tape type having a fluorescent mixture thereon, and the tape is tied to an adhesive layer, and the adhesive layer is deposited on the light emitting layer. On the polar body. Typically, the wavelength converting layer is initially fabricated on a substrate and removed from the substrate and attached to the die using a capillary device that is attached to a vacuum supply.

Please refer to FIG. 1 for a conventional system for processing a wavelength conversion layer, including A plurality of wavelength conversion layers 10, the plurality of wavelength conversion layers 10 being included on a substrate 12 having an adhesive tape 14 for attaching the wavelength conversion layer 10 to the substrate 12. . For removing the wavelength conversion layer 10 from the substrate 12, a capillary device 16 is used and used in conjunction with an ejection pin 18. However, due to the adhesiveness of the adhesive tape 14, the removal of the wavelength conversion layer 10 from the substrate 12 requires a large force. As shown in Fig. 2, it may cause cracks 20 or other damage of the wavelength conversion layer 10, and the wavelength conversion layer may change the color of the mixed white light generated by a light-emitting diode die.

Since any damage to the wavelength converting layer during fabrication can alter the output of the die, it is difficult to produce a white light emitting diode die having a consistent color balance. The present invention is directed to a system for fabricating light emitting diode dies and methods thereof that minimize damage to the wavelength converting layer.

A system for fabricating a light-emitting diode die includes a light-emitting diode die and a wavelength conversion layer, the wavelength conversion layer structure being attached to an energy sensitive adhesive layer, The adhesive layer architecture reduces adhesion by exposure to physical energy such as electromagnetic radiation or thermal energy. The system also includes a curing apparatus and an attachment apparatus that reduces the adhesion of the adhesive layer to assist in removing the wavelength conversion layer from the substrate, the attachment apparatus The architecture is configured to remove the wavelength conversion layer from the substrate and attach the wavelength conversion layer to the light emitting diode die.

A method for fabricating a light emitting diode die, comprising the steps of: providing a light emitting diode die having a desired configuration; and providing a wavelength conversion layer comprising a substrate; The substrate is attached to an energy-sensitive adhesive layer that is exposed to a physical energy to reduce adhesion. The method also includes the steps of exposing the adhesive layer on the substrate to the physical energy to reduce adhesion of the adhesive layer and to assist in removing the wavelength conversion layer from the substrate; Removing the substrate; and attaching the wavelength conversion layer to the light emitting diode die.

10‧‧‧wavelength conversion layer

12‧‧‧Substrate

14‧‧‧Adhesive tape

16‧‧‧Capillary device

30‧‧‧Light-emitting diode grains

32‧‧‧Electrical substrate

34‧‧‧n type limited layer

36‧‧‧Multi-quantum wells

38‧‧‧p type limited layer

40‧‧‧ epitaxial stacking

42‧‧‧wavelength conversion layer

44‧‧‧n electrode

46‧‧‧p electrode

48‧‧‧Characteristics

54‧‧‧Opening

60‧‧‧Flat-type light-emitting diode crystal grains

62‧‧‧Transparent substrate

64‧‧‧ epitaxial stacking

66‧‧‧n type limited layer

68‧‧‧Multi-quantum wells

70‧‧‧p type limited layer

72‧‧‧Transparent conductive layer

74‧‧‧p electrode

76‧‧‧n electrode

78‧‧‧wavelength conversion layer

80‧‧‧First opening

82‧‧‧Second opening

90‧‧‧ system

92‧‧‧Substrate

94‧‧‧Energy-sensitive adhesive layer

96‧‧‧Curing equipment

98‧‧‧ Attached equipment

90A‧‧‧ system

94A‧‧‧Adhesive layer

96A‧‧‧Curing equipment

90B‧‧‧ system

94B‧‧‧Energy-sensitive adhesive layer

96B‧‧‧Hot curing equipment

100‧‧‧ capillary

102‧‧‧Vacuum device

106A‧‧‧Selected area

104B‧‧‧ Thermal Energy

106B‧‧‧Selected area

Figure 1 is a schematic cross-sectional view showing a conventional system for processing a wavelength conversion layer.

Figure 2 is a schematic cross-sectional view showing one of the wavelength conversion layers during processing by a conventional wavelength conversion layer.

Figure 3 is a schematic cross-sectional view showing a crystal of a light-emitting diode of the present invention having a wavelength conversion layer.

Figure 4 is a schematic cross-sectional view showing a second light-emitting diode of one of the wavelength conversion layers of the present invention.

Figure 5 is a schematic diagram showing a system for fabricating a light-emitting diode die having a plurality of wavelength converting layers, respectively, of the present invention.

Fig. 5A is a plan view, as seen from line 5, along line 5A-5A, showing a circumferential shape of one of the wavelength conversion layers of the system.

Figure 5B is a side view of Figure 5A.

6A and 6B are schematic cross-sectional views showing a pick and place mechanism of the system of the present invention and an ultraviolet curing apparatus.

7A and 7B are schematic cross-sectional views showing a pick and place mechanism of the system of the present invention and a heat curing apparatus.

It is understood that when an element is referred to as "on" another element, it can be directly on the other element or the intervening elements can be present. However, the term "directly" means that no component is inserted. Furthermore, although the terms "first", "second", and "third" are used to describe different elements, these elements should not be limited by these terms. Moreover, unless otherwise defined, all terms are intended to have the same meaning as understood by those skilled in the art.

Referring to FIG. 3, a light emitting diode die 30 is illustrated. The light-emitting diode die 30 is in the form of a vertical light emitting diode. For the sake of simplicity, the different elements of the light-emitting diode die 30 will not be depicted. However, this type of luminescent diode die 30 is further described in U.S. Patent No. 7,615,789 which is incorporated herein by reference. Although the light-emitting diode crystal 30 is described as a direct-emitting diode, it is understood that the concept described herein can also be applied to other types of light-emitting diode crystals. Granules, such as luminescent diode dies having planar electrode configurations.

The light emitting diode die 30 includes a conductive substrate 32 and an epitaxial stack 40 on the conductive substrate 32. The epitaxial stack 40 includes an n-type confinement layer 34, a multiple quantum well (MQW) layer 36, and a p-type confinement layer 38, and the n-type confinement layer 34 is configured to emit electromagnetic radiation. The multi-quantum well layer 36 is in contact with the n-type confinement layer 34, and the p-type confinement layer 38 is in contact with the multi-quantum well layer 36.

Preferably, the n-type confinement layer 34 comprises n-GaN. Other suitable materials for the n-type confinement layer 34 include n-AlGaN, n-InGaN, n-AlInGaN, and n-AlN. Preferably, the multi-quantum well layer 36 comprises one or more quantum wells, each quantum well system comprising one or more layers of InGaN/GaN, AlGaInN, AlGaN, AlInN, and AlN. The multi-quantum well 36 system can be constructed from the visible spectrum range (ie 400~770nm), the violet blue spectrum range (ie 400~450nm), the blue spectrum range (ie 450~490nm), the green spectrum range (ie 490~). 560 nm), the yellow spectrum range (ie 560~590 nm), the orange spectrum range (ie 590~635 nm), or the red spectrum range (ie 635~700 nm) emits electromagnetic radiation. Preferably, the p-type confinement layer 38 comprises p-GaN. . Other suitable materials for the p-type confinement layer 38 include p-AlGaN, p-InGaN, p-AlInGaN, p-AlInN, and n-AlN.

Still referring to FIG. 3, the LED die 30 includes an n-electrode 44 and a p-electrode 46, wherein the n-electrode 44 is on the n-type confinement layer 34, and the p-electrode 46 is on the conductive substrate 32. Above the backside. The n-electrode 44 and the p-electrode 46 may comprise a conductive material, such as a metal, a metal alloy or a single layer of a metal stack such as ':W, Ti, Mo, Al, Cu, Ni, Ag, Au or Co, the metal alloy is, for example, Cu-Co or Cu-Mo, and the metal stack is, for example, Ni/Cu or Ni/Cu-Mo.

The light-emitting diode die 30 also includes a wavelength conversion layer 42 formed over the epitaxial stack 40 and in contact with the m-type confinement layer 34. The wavelength conversion layer 42 also includes an opening 54 that is aligned with the n-electrode 44 to provide access to the n-electrode 44. The wavelength conversion layer 42 is configured to convert at least some of the electromagnetic radiation emitted by the multi-quantum well layer 36 to electromagnetic radiation having a different wavelength range, such as a higher wavelength range. Incidentally, if the multi-quantum well layer 36 emits electromagnetic radiation in a range of the blue light spectrum, the wavelength conversion layer 42 can be configured to convert at least some of the radiation into a yellow spectral range to enable White light is emitted from the output of the photodiode die 30.

Referring to FIG. 4, a planar light-emitting diode die 60 is illustrated. The light emitting diode die 60 includes a transparent substrate 62 and an epitaxial stack 64 over the transparent substrate 62. The epitaxial stack 64 includes an n-type confinement layer 66, a multi-quantum well layer 68, and a p-type confinement layer 70, wherein the multi-quantum well layer 68 is electrically in contact with the n-type confinement layer 66, and the n-type is limited. The layer 66 is structured to emit electromagnetic radiation, and the p-type confinement layer 70 is in electrical contact with the multi-quantum well layer 68. The planar light-emitting diode die 60 also includes a transparent conductive layer 72 and a p-electrode 74 over the p-type confinement layer 70. The planar light-emitting diode die 60 is also included with an n-electrode 76 over the n-type confinement layer 66. The planar light-emitting diode die 60 also includes a wavelength conversion layer 78 having a first opening 80 and a second opening 82. The first opening 80 is aligned with the n-electrode 76. The second opening 82 is aligned with the p-electrode 74. The wavelength conversion layer 78 is substantially configurable as described above for the wavelength conversion layer 42 (as shown in FIG. 2).

Referring to FIG. 5, a system 90 for fabricating light-emitting diode dies includes a light-emitting diode die 30 (or 60) having a desired structure, and a structure for attaching to the light-emitting diode crystal. A plurality of wavelength conversion layers 42 of particles 30 (or 60). The wavelength conversion layer 42 is included on a substrate 92 which is attached to an energy-sensitive adhesive layer 94. The energy-sensitive adhesive layer 94 is structured to reduce adhesion according to exposure to a physical energy such as electromagnetic. Radiation, ultraviolet, infrared, radioactive or thermal energy. System 90 also includes a curing device 96 that is configured to reduce the adhesion of adhesive layer 94 to aid in the removal of wavelength conversion layer 42 from substrate 92. The system 90 also includes an attachment device 98 that is configured to remove the wavelength conversion layer 42 one by one from the substrate 92 and individually attach the wavelength conversion layer 42 to the light emitting diode die 30 ( Or 60).

The substrate 92 can be a wafer type or a panel type having a desired size. Suitable materials for the substrate 92 include plastic, metal, ceramic, and semiconductor materials. The adhesive layer 94 can be formed directly on the surface of the substrate 92. For example, the adhesive layer 94 (as shown in FIG. 5) may include a tape or a deposited layer that is exposed to physical energy such as ultraviolet, infrared, radiant or thermal energy. At least one of the adhesive surfaces on the adhesive layer 94 has a reduced adhesion. The illustrated belt system includes polymer films such as polyethylene, polypropylene, polyester. (polyester) or polycarbonate, and has an adhesive such as an acrylic polymer on one or both sides of the belt. A suitable belt system is REVALPHA thermal release tape manufactured by Nitto Denko, Japan, and is available in the United States via Semiconductor Equipment Corporation of Moorpark, CA 93020. When not a strip, the adhesive layer 94 may include a deposited polymer having adhesive qualities, such as polyimide or epoxy in a cured or uncured state. ).

The wavelength converting layer 42 (shown in Figure 5) can be formed directly on the adhesive layer 94 having the desired circumferential shape and thickness and using a suitable process such as deposition and patterning. . For example, as shown in FIG. 5A, the wavelength conversion layer 42 has a polygonal circumferential shape that is substantially associated with the light-emitting diode die 30 (as shown in FIG. 3) or 60 (as shown in FIG. 4). The circumferential shape of the epitaxial stack 40 (shown in Figure 3) or 64 (as shown in Figure 4) matches. As shown in Figures 5A and 5B, the wavelength conversion layer 42 can also include one or more features 48, such as cut outs, openings, and slots. Corresponds to features above the LED die 30 (as shown in Figure 3) or 60 (as shown in Figure 4). For example, feature 48 can be aligned with n-electrode 44 (shown in Figure 3) over light-emitting diode die 30 (shown in Figure 3).

The wavelength conversion layer 42 may comprise a transparent substrate material comprising a wavelength conversion material such as plastic, glass, ceramic or an adhesive polymer, such as a fluorescent mixture (for example, a fluorescent mixture) Phosphor compound). In this example, the wavelength converting material can be incorporated into the substrate material, using a mixing process to form a different mixture, which can then be deposited on the adhesive layer 94 to have a desired circumferential shape and thickness. And solidified into a solid form. The base material exemplified for the wavelength conversion layer 42 includes a liquid form or a viscous form of silicone and epoxy, which can be combined with a special ratio. The wavelength conversion materials of the (specific ratio) are mixed. The wavelength conversion materials exemplified include YAG:Ce, TAG:Ce, Eu-doped alkaline earth silicon nitride, Eu-doped alkaline earth silicate or Ce-doped Calcium scandate. When not bonded to the substrate material, the wavelength converting material can be deposited on the substrate material. In this case, the base material can be deposited on the stick. Above the layer 94, and the wavelength converting material can be deposited on the substrate material in a desired pattern using a suitable process to form a desired thickness, such as spraying, dipping, spin plating ( Spin coating), rolling, electro deposition or vapor deposition.

Curing device 96 (shown in Figure 5) may include a source of ultraviolet, infrared, thermal or radiative radiation that is configured to provide a desired energy to a selected area of adhesive layer 94. For example, curing device 96 can be constructed such that adhesive layer 94 can be locally cured in selected regions so that each wavelength conversion layer can be individually removed. Further, curing device 96 is an adhesive layer 94 that can be constructed to cure in a region that corresponds to the exterior of an additional adhesive layer 94.

The attachment device 98 (as shown in FIG. 5) can include a capillary device that is configured to extract the wavelength conversion layer 42 from the substrate 92 and place the wavelength conversion layer 42 on the light emitting diode die. Above 30 (or 60). Attachment device 98 can also include a stepper mechanism, such as an x-y table, that is configured to align substrate 92 with the capillary device.

Referring to Figures 6A and 6B, a system 90A includes an adhesive layer 94A that is structured to reduce adhesion by exposure to ultraviolet radiation. System 90A includes a curing device 96A that is configured to concentrate ultraviolet radiation onto a selected area. As shown in Fig. 6B, the selected region 106A for lowering the adhesion has a circumferential shape corresponding to the circumferential shape of the wavelength conversion layer 42. System 90A also includes a capillary 100 in communication with a vacuum 102 that is configured to extract wavelength converting layer 42 from substrate 92 and to place wavelength converting layer 42 on the crystal. Above the pellet 30 (or 60).

Referring to FIGS. 7A and 7B, a system 90B includes an energy-sensitive adhesive layer 94B that is structured to reduce the adhesive layer by exposure to thermal energy. System 90B includes a hot bar curing device 96B that is configured to direct thermal energy 104B to a selected region 106B for heating adhesive layer 94B. As shown in Fig. 6B, the selected region 106B for lowering the adhesion has a circumferential shape corresponding to the circumferential shape of the wavelength conversion layer 42. System 90B also includes a capillary tube 100 in communication with a vacuum device 102 that is configured to extract wavelength conversion layer 42 from substrate 92 and place wavelength conversion layer 42 on die 30 (or 60) above.

While the foregoing is directed to the various embodiments of the present invention, further or further embodiments of the present invention may be devised without departing from the basic scope thereof, and the basic scope thereof is defined by the following claims. Although the present invention has been explained in connection with the preferred embodiments, it is not intended to limit the invention. It should be noted that many other similar embodiments can be constructed in accordance with the teachings of the present invention, which are within the scope of the present invention.

30‧‧‧Light-emitting diode grains

32‧‧‧Electrical substrate

34‧‧‧n type limited layer

36‧‧‧Multi-quantum wells

38‧‧‧p type limited layer

40‧‧‧ epitaxial stacking

42‧‧‧wavelength conversion layer

44‧‧‧n electrode

46‧‧‧p electrode

54‧‧‧Opening

Claims (20)

A system for fabricating a light-emitting diode die includes: a light-emitting diode die; a wavelength conversion layer attached to the light-emitting diode die, the light-emitting diode die is included in On a substrate, the substrate is attached to an adhesive layer structure that is exposed to a physical energy to reduce adhesiveness; a curing apparatus, An architecture to reduce adhesion of the adhesive layer to assist removal of the wavelength conversion layer from the substrate; and an attachment apparatus to remove the wavelength conversion layer from the substrate and convert the wavelength A layer is attached to the light emitting diode die. The system of claim 1, wherein the wavelength conversion layer has a first peripheral shape substantially corresponding to an area on the light emitting diode die A second circumferential shape conforms. The system of claim 1, wherein the wavelength conversion layer comprises one or more features corresponding to one or more of the luminescent diode dies Feature calibration (align). The system of claim 1, wherein the physical energy comprises ultraviolet radiation, and the curing apparatus comprises an ultraviolet radiation curing apparatus. The system of claim 1, wherein the physical energy system comprises thermal energy, and the curing device comprises a hot bar curing device. A system for fabricating a light-emitting diode die includes: a light-emitting diode die; a plurality of wavelength conversion layers on a substrate, the substrate being attached to an adhesive layer, the adhesion layer The structure is based on exposure to an electromagnetic radiation to reduce adhesiveness, each wavelength conversion layer structure is attached to the light emitting diode die and has a first circumferential shape; a curing device a structure for providing a physical energy on the adhesive layer of a selected area of the curing device to reduce the adhesion of the adhesive layer, the selected area Having a second circumferential shape corresponding to the first circumferential shape; and an attachment device for removing the wavelength conversion layers from the substrate one at a time and converting the wavelengths A layer is attached to the light emitting diode die. The system of claim 6, wherein the physical energy is a radiation selected from the group consisting of ultraviolet, infrared, radioactive, and heat. The system of claim 6 wherein each wavelength conversion layer comprises a feature selected from the group consisting of: cut outs, openings, and slots (slots) ). The system of claim 6 wherein the physical energy comprises ultraviolet radiation and the curing apparatus comprises an ultraviolet radiation curing apparatus. A system according to claim 6 wherein the physical energy system comprises thermal energy and the curing device comprises a hot bar curing device. The system of claim 6 wherein the wavelength converting layer comprises a base material and a phosphor compound mixed into the base material. The system of claim 6 wherein the wavelength converting layer comprises a substrate material and a fluorescent mixture deposited on the substrate material. The system of claim 6 wherein the light emitting diode die comprises a vertical LED die. The system of claim 6 wherein the light emitting diode die comprises a planar LED die. A method of fabricating a light emitting diode die, comprising: providing a light emitting diode die having a desired configuration; providing a wavelength conversion layer on a substrate, the substrate being attached On the adhesive layer, the adhesive layer is structured to expose a physical energy to reduce adhesion; the adhesive layer on the substrate is exposed to the physical energy to reduce the adhesion of the adhesive layer and to assist in the wavelength conversion. The layer is removed from the substrate; Removing the wavelength conversion layer from the substrate; and attaching the wavelength conversion layer to the light emitting diode die. The method of claim 14, wherein the step of providing a light-emitting diode die comprises providing a plurality of wavelength conversion layers on a substrate on the adhesive layer, and the step of exposing comprises bonding the bond A selected area of the layer is exposed, and the selected area of the adhesive layer has a circumferential shape that corresponds to a circumferential shape of the light-emitting diode die. The method of claim 14, wherein the physical energy system comprises ultraviolet radiation, and the step of exposing is performed using an ultraviolet radiation curing device. The method of claim 14, wherein the physical energy system comprises thermal energy, and the step of exposing is performed using a hot press curing device. The method of claim 14, wherein the wavelength conversion layer comprises a feature selected from the group consisting of: cut outs, openings, and slots. The method of claim 14, wherein the light emitting diode crystal grain comprises a direct light emitting diode crystal grain or a planar light emitting diode crystal grain.