CN101540314A - Light emitting diode element and method of forming the same - Google Patents

Abstract

The invention provides a light emitting diode element and a method for forming the same. The light-emitting diode element comprises a substrate, a plurality of first light-emitting diode cores formed on the substrate, and a transparent substrate arranged opposite to the substrate, wherein the transparent substrate is provided with a first surface facing the substrate and an opposite second surface, and a patterned conductive layer formed on the first surface, and the patterned conductive layer is electrically connected with the first light-emitting diode cores and is connected with the first light-emitting diode cores in series.

Description

Light emitting diode element and method of forming the same

technical field

The invention relates to a light-emitting diode element, and in particular to an AC light-emitting diode element.

Background technique

Due to the advantages of small size, low power consumption, fast response rate, and long service life, light-emitting diodes (LEDs) have been widely used in various forms such as household lighting, computer peripheral equipment, communication products, traffic signal signs, and car lights. Applications. A light emitting diode generally includes a p-type semiconductor layer, an n-type semiconductor layer, and a pn junction between the two material layers. When a forward current is applied to the LED, holes from the p-type semiconductor layer and electrons from the n-type semiconductor layer can combine at the pn junction to release photons. Compared with traditional lighting equipment (such as light bulbs), only one energy conversion is required to directly convert electrical energy into light energy, which has a high energy conversion rate, can emit high-brightness light and save energy.

In general LED lighting equipment, it is necessary to convert the AC power into a low DC voltage (between about 1V and 5V) and a high DC current (about less than 100mA) through an additional circuit to make the LED emit light. However, the process of power conversion through additional circuits will cause power loss. In addition to reducing the energy conversion rate, it is easy to increase the temperature of the LED lighting equipment and affect the operation of the LED. In addition, the adoption of additional circuits will increase the manufacturing cost and reduce the space utilization.

The world patent WO2006004337 discloses a light-emitting diode, each light-emitting diode is connected by wires, and the reliability will decrease with the increase of the number of light-emitting diodes. US Patent No. 20060169993 uses a conductive film as the electrical connection between each LED. In order to prevent conduction on the side walls of the LEDs, an insulating layer needs to be coated first to isolate the LEDs. US Pat. No. 7,128,438 discloses using conductive wires on transparent spacers as electrical connections between each LED.

Contents of the invention

The invention provides a light emitting diode element, comprising a substrate, a plurality of first light emitting diode dies formed on the substrate, a transparent substrate disposed opposite to the substrate, the transparent substrate has a first surface facing the substrate and an opposite second surface, and a patterned conductive layer formed on the first surface, and the patterned conductive layer is electrically connected with the first light emitting diode die to connect the first light emitting diode die in series.

The present invention further provides a method for forming a light-emitting diode element, which includes providing a substrate on which a plurality of first light-emitting diode dies are formed, providing a transparent substrate so that it is arranged opposite to the substrate, and the transparent substrate has a first surface and an opposite surface. On the second surface, a patterned conductive layer is formed on the first surface, and the transparent substrate is reversed so that the first surface faces the base, and aligned and attached to the base, so that the patterned conductive layer is electrically connected to the first light emitting diode die. The first light-emitting diode dies are connected in series.

In order to make the above-mentioned and other objects, features, and advantages of the present invention more comprehensible, the preferred embodiments are listed below, together with the accompanying drawings, and are described in detail as follows.

Description of drawings

FIG. 1 shows a substrate on which a plurality of LED dies are formed in an embodiment of the present invention.

FIG. 2 a shows a cross-sectional view of a transparent plate used to connect LED dies in series according to an embodiment of the present invention.

FIG. 2 b shows a top view of a transparent plate used to connect LED dies in series according to an embodiment of the present invention.

FIG. 3 a shows a cross-sectional view of an LED device according to an embodiment of the present invention.

FIG. 3b shows a top view of a light emitting diode device according to an embodiment of the present invention.

FIG. 3c shows a schematic circuit diagram of LED elements connected in series with an AC power source in an embodiment of the present invention.

FIG. 4 shows a schematic circuit diagram of a light emitting diode device according to an embodiment of the present invention.

FIG. 5 shows a cross-sectional view of an LED device according to another embodiment of the present invention.

Explanation of reference signs

100: Substrate 101: Epitaxial substrate

110: first light-emitting diode die 110p: p-type electrode

110n: n-type electrode 102: n-type semiconductor layer

104: light-emitting layer 106: p-type semiconductor layer

108: Current distribution layer 112: Transparent substrate

112a: first surface 112b: second surface

114: Conductive layer 114a: Patterned conductive layer

30: AC power supply 110a: Second LED die

116: Phosphor powder layer 100a: Transparent base

Detailed ways

The invention provides a light-emitting diode element and its forming method. By covering and bonding a transparent substrate with a patterned conductive layer formed thereon on a base with a plurality of light-emitting diode dies, the plurality of light-emitting diode dies see through the pattern The conductive layers are connected in series with each other, and AC power can be directly supplied to make it emit light without additional circuits.

1-3 show the fabrication process of an embodiment of the present invention. FIG. 1 shows a substrate on which a plurality of LED dies are formed in an embodiment of the present invention. As shown in FIG. 1 , a substrate 100 is provided first. In one embodiment, a plurality of independent LED dies 110 can be bonded on the substrate 100 . In another embodiment, an epitaxial substrate of a light emitting diode can also be directly used as the substrate 100 , and the epitaxial stacked layer thereon can be patterned to form a plurality of separated light emitting diode dies 110 on the substrate 100 . Each first LED die further includes a p-type electrode 110p and an n-type electrode 110n. In the subsequent process, the p-type electrode 110p and the n-type electrode 110n will be in electrical contact with the patterned conductive layer formed on the transparent substrate, and through the patterned conductive layer, they will be connected to an external power source (such as an AC power source) or other light-emitting diode tubes. core electrical connection. The p-type electrode 110p may include gold, nickel, platinum, aluminum, tin, indium, chromium, titanium, alloys of the foregoing, stacks of the foregoing, or combinations of the foregoing. The n-type electrode 110n may include titanium, aluminum, gold, copper, zinc, the aforementioned alloys, the aforementioned stacked layers, or a combination of the aforementioned. The LED die 110 can emit light of approximately a single wavelength, which can be ultraviolet light, visible light, or infrared light.

In one embodiment, the first LED die 110 can be composed of an epitaxial substrate 101, an n-type semiconductor layer 102, a p-type semiconductor layer 106, and a light-emitting layer sandwiched between the n-type semiconductor layer 102 and the p-type semiconductor layer 106. 104, and directly attached to the substrate 100. In another embodiment, part or all of the epitaxial substrate 101 of the plurality of light emitting diode dies 110 is ground off first, and then bonded on the substrate 100 . In one embodiment, an epitaxial substrate is used as the substrate 100, and through a stack of epitaxially grown material layers thereon, for example, including an n-type semiconductor layer 102, a light-emitting layer 104, and a p-type semiconductor layer 106 in sequence, and then the transparent Part of the material layer is removed by the over-etching process, and a plurality of LED dies 110 are formed on the substrate 100 . The material of the epitaxial substrate 101 can be sapphire (Al ₂ O ₃ ), silicon carbide, silicon, or gallium arsenide. 110 The material of the n-type semiconductor layer 102, the p-type semiconductor layer 106, and the light-emitting layer 104 may include gallium nitride, gallium phosphide, gallium arsenic phosphide, or a combination of the foregoing, and the aforementioned material layers may be modified as required. doping. The light emitting layer 104 can be a single structure, a double-hetero structure (DH), or a multi quantum well structure (multi quantum well, MQW). In addition, as shown in FIG. 1, the n-type electrode 110n is located on the lower n-type semiconductor layer 102. In order to be electrically connected with the patterned conductive layer on the transparent substrate in the subsequent process, the n-type electrode 110n may include an n-type junction. Pads and bumps (not shown) are of sufficient height (approximately the same height as the p-type electrode 110p) to bond with the patterned metal layer.

In one embodiment, a current spreading layer 108 (current spreading layer) is formed on the p-type semiconductor layer 106 , so that current can be more easily and uniformly injected into the p-type semiconductor layer 106 with higher resistance. The material of the current distribution layer 108 may include metal materials such as gold, nickel, platinum, aluminum, tin, indium, chromium, titanium, alloys of the foregoing, stacks of the foregoing, or combinations of the foregoing. The material of the current distribution layer 108 may also include transparent conductive oxides, such as ITO (indium tin oxide), CTO (cadmium tin oxide), IZO (indium zinc oxide), ZnO:Al, ZnGa ₂ O ₄ , SnO ₂ :Sb, Ga ₂ O ₃ :Sn, AgInO ₂ :Sn, In ₂ O ₃ :Zn, CuAlO ₂ , LaCuOS, NiO, CuGaO ₂ , SrCu ₂ O ₂ , the foregoing stacks, or a combination of the foregoing. In one embodiment, the current distribution layer 108 is preferably made of a transparent material with low light absorption rate and low reflectance rate. In another embodiment, the current distribution layer 108 can also be made of translucent material.

Next, a transparent plate for connecting the LED dies 110 in series is fabricated. As shown in Figure 2a, a transparent substrate 112 is provided. The transparent substrate may include a flexible transparent substrate (such as polyimide) or a rigid transparent substrate (such as glass or quartz, etc.). The transparent substrate 112 has a first surface 112a and an opposite second surface 112b. In subsequent processes, a patterned conductive layer will be formed on the first surface 112 a of the transparent substrate 112 . In one embodiment, a conductive layer 114 may be formed on the first surface 112a first, and then the conductive layer 114 may be patterned into a patterned conductive layer by means such as photolithography and etching, energy beam etching (such as laser) and the like. 114a. In addition, a lift-off process can also be used to form a patterned photoresist layer (not shown) on the transparent substrate 112 first, then deposit the conductive layer 114, and then lift off the patterned photoresist layer, the patterned conductive layer 114 a can be left on the transparent plate 112 . FIG. 2 b shows a top view of the first surface 112 a facing the transparent substrate 112 in an embodiment of the present invention. In subsequent processes, the patterned conductive layer 114a will serve as a conductive path between the plurality of first LED dies 110 in the substrate 100 , so that the plurality of first LED dies 110 can be connected in series. The patterned conductive layer 114 a can also be connected to an AC power source to form an electrical connection between the AC power source and the plurality of first LED dies 110 connected in series. The material of the patterned conductive layer 114a can be a transparent conductive layer, a semi-transparent conductive layer, or an opaque conductive layer. In one embodiment, the material of the patterned conductive layer 114a is preferably a transparent conductive layer, which may be an organic transparent conductive layer, an inorganic transparent conductive layer, or a combination thereof.

Next, as shown in FIG. 3 a , the transparent substrate 112 is reversed so that the first surface 112 a faces the substrate 100 , and is aligned and bonded on the substrate 100 to form a light emitting diode element in an embodiment of the present invention. The patterned conductive layer 114a on the first surface 112 can be connected to the p-type electrodes and the n-type electrodes on the plurality of first light-emitting diode dies 110 respectively through thermal pressing or other suitable methods, and electrically connected in series. The plurality of first LED dies 110 . In one embodiment, the n-type electrode 110n of the LED die is electrically connected to the p-type electrode 110p of the other LED die through the patterned conductive layer 114a, and the n-type electrode 110p of the other LED die 110n is also electrically connected to the p-type electrode 110p of the next LED die through another patterned conductive layer 114a, so that a plurality of first LED dies 110 are connected in series one by one. Figure 3b shows a top view of an embodiment of the present invention. By inverting the transparent substrate 112 and aligning and attaching it to the substrate 100 , the patterned conductive layer 114 a on the first surface 112 a of the transparent substrate 112 can connect a plurality of first LED dies 110 in series.

In one embodiment, the patterned conductive layer 114 a is also electrically connected to the AC power source 30 . The light emitting diode element in the embodiment of the present invention can directly use an AC power source to emit light. Due to the material properties of the LED core itself, it is necessary to apply a positive bias voltage to the p-type electrode 110p and a negative bias voltage to the n-type electrode to make the LED core emit light. Therefore, the plurality of LED dies 110 in this embodiment will emit light in the positive half cycle of the AC power supply 30, and when the voltage of the AC power source 30 is in the negative half cycle, the plurality of LED dies 110 will be reverse biased Pressed (reverse-biased) and unable to shine. However, since the positive and negative periods of the AC power supply are smaller than the intervals that can be recognized by naked eyes, the plurality of LED dies 110 are still generally emitting light continuously under visual inspection. FIG. 3c shows a schematic circuit diagram of LED elements connected in series with an AC power source in an embodiment of the present invention. The number of LED dies connected in series can be adjusted according to the situation, preferably so that each LED die is distributed with a suitable operating voltage. In one embodiment, resistors or variable resistors can be formed to adjust the operating voltage distributed to each LED die.

In addition, in the embodiment of the present invention, in addition to connecting the first LED dies 110 in series through the patterned conductive layer, other second LED dies can also be connected in series. FIG. 4 shows a schematic circuit diagram of a plurality of other second LED dies connected in series in an embodiment of the present invention. As shown in FIG. 4 , the series connection among the plurality of first light-emitting diode dies 110 is the same as that described in FIG. 3 b , which is a forward series connection. The series connection method of the plurality of second LED dies 110a is opposite, which is reverse series connection. The arrays of two serially connected LED dies are connected in parallel with each other and also with the AC power source 30 . When the AC power source 30 is in a positive half cycle, the plurality of first LED dies 110 will emit light while the plurality of second LED dies 110a will not emit light. Conversely, when the AC power source 30 is in the negative half cycle, the plurality of second LED dies 110a will emit light while the plurality of first LED dies 110 will not emit light, thereby providing more stable illumination. The embodiment shown in FIG. 4 is formed in a manner similar to the embodiments described above. First, a substrate is provided on which a plurality of first LED dies and a plurality of second LED dies are formed. Then, a patterned conductive layer is formed on the transparent substrate, and the transparent substrate is reversed and bonded to the base to complete.

FIG. 5 shows a cross-sectional view of an LED device according to another embodiment of the present invention. As shown in FIG. 5 , a phosphor layer 116 can also be formed on the second surface 112 b of the transparent substrate 112 . The phosphor layer 116 can absorb partially or completely the light emitted by the LED die, and convert the absorbed light into light with a lower wavelength, so as to provide the desired light color. The material of the phosphor layer 116 may include organic phosphor, inorganic phosphor, or a combination thereof. In addition, phosphors that can emit various colors of light can be selected for the phosphor layer 116 , such as red phosphors, green phosphors, blue phosphors, yellow phosphors, or combinations thereof. In addition, in one embodiment, phosphors of different materials can be formed on different regions on the second surface 112 b of the transparent substrate 112 . Each area under the phosphor layer may correspond to a first LED die, a second LED die, a plurality of first LED dies, a plurality of second LED dies, or a combination thereof. The desired visual effects can be adjusted through different phosphor materials and the underlying LED dies corresponding to different light emitting periods.

The embodiment of the present invention has many advantages. Through a simple process, a plurality of light-emitting diode dies can be connected in series, and the AC power can be directly used to emit light. There is no need for an additional circuit to convert the AC power to a DC power, which can reduce power consumption. Reduce production costs and improve space utilization.

Although the present invention has been disclosed above with a number of preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can make any changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims (20)

1. A light emitting diode element, comprising: base; a plurality of first LED dies formed on the substrate; a transparent substrate, disposed opposite to the base, the transparent substrate has a first surface facing the base and an opposite second surface; and A patterned conductive layer is formed on the first surface, and the patterned conductive layer is electrically connected to the first LED die to connect the first LED die in series. 2. The LED device as claimed in claim 1, wherein the first LED die comprises an ultraviolet LED die, a visible light LED die, an infrared LED die, or a combination thereof. 3. The LED device as claimed in claim 1, wherein the transparent substrate comprises a flexible transparent substrate or a rigid transparent substrate. 4. The LED device as claimed in claim 1, wherein the patterned conductive layer comprises a transparent conductive layer, an opaque conductive layer, or a combination thereof. 5. The LED device as claimed in claim 1, wherein the patterned conductive layer comprises an organic transparent conductive layer, an inorganic transparent conductive layer, or a combination thereof. 6. The LED device as claimed in claim 1, further comprising a phosphor layer formed on the second surface. 7. The LED device as claimed in claim 6, wherein the phosphor layer comprises organic phosphor, inorganic phosphor, or a combination thereof. 8. The LED device as claimed in claim 6, wherein the phosphor layer comprises red phosphor, green phosphor, blue phosphor, yellow phosphor, or a combination thereof. 9. The light emitting diode element according to claim 1, further comprising a plurality of second light emitting diode dies, formed on the substrate, connected in series with each other through the patterned conductive layer, and connected to the first light emitting diode dies in parallel. 10. The LED device as claimed in claim 9, wherein the first LED dies are forwardly connected in series, and the second LED dies are reversely connected in series. 11. A method of forming a light emitting diode element, comprising: providing a substrate on which a plurality of first light emitting diode dies are formed; providing a transparent substrate so as to be disposed opposite to the base, the transparent substrate having a first surface and an opposite second surface; forming a patterned conductive layer on the first surface; and Reversing the transparent substrate, making the first surface face the base, aligning and attaching it to the base, electrically connecting the patterned conductive layer with the first LED tube core and connecting the first LED tube in series core. 12. The method for forming an LED device as claimed in claim 11, wherein the first LED die comprises an ultraviolet LED die, a visible light LED die, an infrared LED die, or a combination thereof. 13. The method for forming a light emitting diode device as claimed in claim 11, wherein the transparent substrate comprises a flexible transparent substrate or a rigid transparent substrate. 14. The method for forming a light emitting diode device as claimed in claim 11, wherein the patterned conductive layer comprises a transparent conductive layer, an opaque conductive layer, or a combination thereof. 15. The method for forming a light emitting diode device as claimed in claim 11, wherein the patterned conductive layer comprises an organic transparent conductive layer, an inorganic transparent conductive layer, or a combination thereof. 16. The method of forming a light emitting diode device as claimed in claim 11, further comprising forming a phosphor layer on the second surface. 17. The method for forming a light emitting diode device as claimed in claim 16, wherein the phosphor layer comprises organic phosphor, inorganic phosphor, or a combination thereof. 18. The method for forming an LED device as claimed in claim 16, wherein the phosphor layer comprises red phosphor, green phosphor, blue phosphor, yellow phosphor, or a combination thereof. 19. The method for forming a light emitting diode element according to claim 11, wherein the substrate further comprises a plurality of second light emitting diode dies formed in series with each other through the patterned conductive layer, and connected to the first light emitting diode The diode dies are connected in parallel. 20. The method of forming an LED device as claimed in claim 19, wherein the first LED dies are forwardly connected in series, and the second LED dies are reversely connected in series.

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