Patent Description:
A light emitting diode (LED), which is a kind of semiconductor diode, can convert electrical energy into optical energy. A conventional light emitting diode includes a P-N junction having unidirectional conduction. Under a positive bias, holes flow from a P region into an N region and electrons flow from the N region into the P region, and the combination between the electrons in the N region and the holes in the P region produces spontaneous radiation of excitation light. The electrons and the holes have different energy states in different semiconductor materials, therefore the energy produced by the combinations between the electrons and the holes are different. The higher the energy, the shorter the wavelength of the excitation light. Therefore, the LED can emit different light at different wavelengths from ultra-violet light to infrared light, thereby producing a multi-color LED.

The multi-color LED emitting white light or another color light has wide applications, most of which are in the display field. A conventional LED display panel is formed by assembling a monochromatic LED one by one on a substrate. The method for assembling a monochromatic LED includes: bonding the LED by metal wires or connecting electrodes of the LED with an interconnection layer by a metal bonding process or another process. The process of assembling another color LED is not performed until the process of assembling the monochromatic LED is finished, causing a complicated process, increased processing difficulty, and increased production cost. In addition, the multi-color display panel fabricated by assembling or forming single LEDs one by one has a higher power consumption and a decreased luminance and color. <CIT> discloses a light-emitting device and a manufacturing method thereof. <CIT> discloses a III-nitride multi-color on wafer micro-led enabled by tunnel junctions. <CIT> discloses a light-emitting device, method for manufacturing the same, and projector.

According to one aspect of the present invention, a multi-color light emitting pixel unit according to claim <NUM> is provided.

According to another aspect of the present invention, a micro display panel according to claim <NUM> is provided. The micro display panel includes the multi-color light emitting pixel unit described above.

Reference will now be made in detail to the present preferred embodiments to provide a further understanding of the invention. The specific embodiments and the accompanying drawings discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention as defined by the appended claims.

Hereinafter combined with <FIG>, the present disclosure is further described by the embodiments of the disclosure. It should be pointed out that all appended drawings adopt a very simplified form and imprecise scaling is merely used to assistant explain the embodiments of the disclosure conveniently and clearly.

A multi-color light emitting pixel unit disclosed herein at least includes one type of light emitting diode, or several types of light emitting diodes. Each type of light emitting diode includes an upper conductive layer, a bottom conductive layer, and a light emitting layer between the upper conductive layer and the bottom conductive layer. All of the light emitting diodes share the same upper conductive layer and the same bottom conductive layer. It should be noted that, the light emitting layer can be a single layer or multiple layers. A middle layer can be arranged between two of multiple light emitting layers in a same light emitting diode. It is assumed that a multi-color light emitting pixel unit includes first to Mth types of light emitting diodes, where M is an integer and not less than two. Each one of the first to Mth types of light emitting diodes at least includes a same type of light emitting layer. For example, each one of the first to Mth types of light emitting diodes includes a first type of light emitting layer. Any one of the second type to Mth type of light emitting layers is different from the first type of light emitting layer. A micro display panel including a plurality of the pixel units mentioned above arranged in a matrix is also provided in the present disclosure.

In some embodiments, the light emitting diode can be at least one of a light emitting diode (LED), a Schottky light emitting diode, and etc. The top conductive layer of the light emitting diode is, but not limited to, a transparent conductive layer, and the bottom conductive layer of the light emitting diode is, but not limited to, a metal layer. Hereinafter, the LED is used as an example of the light emitting diode, but this does not limit the scope of the present disclosure. A person skilled in the art can change the LED to another light emitting diode according to conventional technical means.

<FIG> is a cross-sectional view illustrating a multi-color light emitting pixel unit <NUM>, according to an embodiment of the present disclosure. Referring to <FIG>, the multi-color light emitting pixel unit <NUM> includes, at least, a first type of LED <NUM> and a second type of LED <NUM> arranged side by side on a substrate <NUM>. The top of the first type of LED <NUM> and the top of the second type of LED <NUM> are not at a same horizontal plane. The type of the first type of LED <NUM> is different from that of the second type of LED <NUM>. Herein, as shown in <FIG>, the top of the first type of LED <NUM> is lower than that of the second type of LED <NUM>. According to an embodiment, the first type of LED <NUM> is selected from one of a red LED, a green LED, a blue LED, a yellow LED, an orange LED, or a cyan LED, and the second type of LED <NUM> is selected from one of a green LED, a blue LED, a red LED, a yellow LED, an orange LED, or a cyan LED. Additionally, the size of a light emitting area of the first type of LED <NUM> is different from that of the second type of LED <NUM>. For example, the first type of LED <NUM> is a red LED, the second type of LED <NUM> is a green LED, and the size of the light emitting area of the red LED is different from that of the green LED. Furthermore, according to different color that may be needed, the light emitting area of the green LED can be smaller than that of the red LED.

In addition, an isolation structure <NUM> is arranged between the first type of LED and the second type of LED. In the embodiment illustrated in <FIG>, the isolation structure <NUM> between the first type of LED <NUM> and the second type of LED <NUM> is an isolation trench. The multi-color light emitting pixel unit <NUM> includes a first metal layer, a first type of light emitting layer, a second metal layer, and a second type of light emitting layer. As illustrated in <FIG>, the first type of LED <NUM> includes, at least, a first segment of a first metal layer <NUM>-<NUM> and a first segment of a first type of light emitting layer <NUM>-<NUM> in an order from bottom to top. The first segment of the first metal layer <NUM>-<NUM> constitutes a bottom conductive layer of the first type of LED <NUM>. The second type of LED <NUM> includes, at least, a second segment of the first metal layer <NUM>-<NUM>, a second segment of the first type of light emitting layer <NUM>-<NUM>, a first segment of a second metal layer <NUM>-<NUM>, and a first segment of a second type of light emitting layer <NUM>-<NUM> in an order from bottom to top, and a first electrical connector <NUM>. The first segment of the first metal layer <NUM>-<NUM> and the second segment of the first metal layer <NUM>-<NUM> are electrically connected with the substrate <NUM>. The isolation structure <NUM> isolates the first segment of the first metal layer <NUM>-<NUM> in the first type of LED <NUM> from the second segment of the first metal layer <NUM>-<NUM> in the second type of LED <NUM>. The isolation structure <NUM> also isolates the first segment of the first type of light emitting layer <NUM>-<NUM> in the first type of LED <NUM> from the second segment of the first type of light emitting layer <NUM>-<NUM> in the second type of LED <NUM>. Additionally, in order to simplify the manufacturing process, the first segment of the second metal layer <NUM>-<NUM>, the second segment of the first type of light emitting layer <NUM>-<NUM>, and the second segment of the first metal layer <NUM>-<NUM> in the second type of LED <NUM> are electrically connected with each other by the first electrical connector <NUM>. According to one embodiment, the first electrical connector <NUM> can be attached to and contact part or all of the side wall surface of the second type of LED <NUM>. Alternatively, the first electrical connector <NUM> can be attached to and contact only the surface of the first segment of the second metal layer <NUM>-<NUM> and the second segment of the first metal layer <NUM>-<NUM> in the second type of LED <NUM>. Still alternatively, the first electrical connector <NUM> can be formed as a conductive side arm attached to and contacting the sidewalls of the first segment of the second metal layer <NUM>-<NUM>, the second segment of the first type of light emitting layer <NUM>-<NUM>, and the second segment of the first metal layer <NUM>-<NUM>. The electrical connector <NUM> between the second segment of the first metal layer <NUM>-<NUM> and the first segment of the second metal layer <NUM>-<NUM> in the second type of LED <NUM> can have another shape, such as a curved line. In the embodiment illustrated in <FIG>, the first electrical connector <NUM> is attached to the sidewall of the second type of LED <NUM>, so that the first electrical connector <NUM> conforms to the surface topography of the side wall of the second type of LED <NUM>.

Referring to <FIG>, a top isolation layer <NUM> and a top transparent conductive layer <NUM> are arranged on the first segment of the first type of light emitting layer <NUM>-<NUM> in the first type of LED <NUM> and the first segment of the second type of light emitting layer <NUM>-<NUM> in the second type of LED <NUM>. The top isolation layer <NUM> covers the first segment of the first type of light emitting layer <NUM>-<NUM>, the first segment of the second type of light emitting layer <NUM>-<NUM>, and the exposed substrate <NUM>. The top isolation layer <NUM> has openings exposing portions of the top surfaces of the first segment of the first type of light emitting layer <NUM>-<NUM> and the first segment of the second type of light emitting layer <NUM>-<NUM>. The top transparent conductive layer <NUM> covers the top isolation layer <NUM> and is formed in the openings of the top isolation layer <NUM>, and thereby contacts the exposed top surfaces of the first segment of the first type of light emitting layer <NUM>-<NUM> and the first segment of the second type of light emitting layer <NUM>-<NUM> via the openings.

The substrate <NUM> is an integrated circuit (IC) substrate. The IC substrate includes an interconnection layer, which is electrically connected with the first segment of the first metal layer <NUM>-<NUM> in the first type of LED <NUM> and the second segment of the first metal layer <NUM>-<NUM> in the second type of LED <NUM>. Since the first electrical connector <NUM> is connected with the second segment of the first metal layer <NUM>-<NUM> in the second type of LED <NUM>, the first electrical connector <NUM> is connected with the interconnection layer in the substrate <NUM>. In addition, referring to <FIG>, the bottom of the first electrical connector <NUM> extends to the substrate <NUM> to connect with the interconnection layer. Herein, the IC substrate at least includes a drive circuit. The drive circuit controls every LED separately.

<FIG> is a cross-sectional view illustrating a multi-color light emitting pixel unit <NUM>, according to an embodiment of the present disclosure. Referring to <FIG>, the multi-color light emitting pixel unit <NUM> includes, at least, the first type of LED <NUM>, the second type of LED <NUM>, and a third type of LED <NUM>, which are arranged on a same substrate <NUM>. The third type of LED <NUM> is different from the first type of LED <NUM> and the second type of LED <NUM>. Herein, the first type of LED <NUM> is selected from one of a red LED, a green LED, a blue LED, a yellow LED, am orange LED, or a cyan LED; the second type of LED <NUM> is selected from one of a green LED, a blue LED, a red LED, a yellow LED, an orange LED, or a cyan LED; and the third type of LED <NUM> is selected from one of a blue LED, a red LED, a green LED, a yellow LED, an orange LED, or a cyan LED. For example, a red LED is selected as the first type of LED <NUM>, a green LED is selected as the second type of LED <NUM>, and a blue LED is selected as the third type of LED <NUM>. Referring to <FIG>, the height of the third type of LED <NUM> is different from that of the first type of LED <NUM>. Furthermore, the height of the first type of LED <NUM> is different from that of the second type of LED <NUM>, while the height of the second type of LED <NUM> is the same as that of the third type of LED <NUM>. In other embodiments, the height of the third type of LED <NUM>, the height of the first type of LED <NUM>, and the height of the second type of LED <NUM> can be different from each other, as shown in <FIG>.

In the multi-color light emitting pixel unit <NUM>, the structures of the first type of LED <NUM> and the second type of LED <NUM> are the same as those of the first type of LED <NUM> and the second type of LED <NUM> in the multi-color light emitting pixel unit <NUM>, and therefore detailed descriptions thereof are not repeated. The third type of LED <NUM> in the multi-color light emitting pixel unit <NUM> includes, at least, a third segment of the first metal layer <NUM>-<NUM>, a third segment of a first type of light emitting layer <NUM>-<NUM>, a first segment of a third metal layer <NUM>-<NUM>, and first segment of a third type of light emitting layer <NUM>-<NUM> in an order from bottom to top, and a second electrical connector <NUM> connecting the third segment of the first metal layer <NUM>-<NUM> and the first segment of the third metal layer <NUM>-<NUM>. The multi-color light emitting pixel unit <NUM> also includes a top isolation layer <NUM> covering the first type of LED <NUM>, the second type of LED <NUM>, and the third type of LED <NUM>, and having opening exposing a portion of the first segment of the first type of light emitting layer <NUM>-<NUM> in the first type of LED <NUM>, a portion of the first segment of the second type of light emitting layer <NUM>-<NUM>, and a portion of the first segment of the third type of light emitting layer <NUM>-<NUM>. A top electrode layer <NUM> is formed on top of the top isolation layer <NUM> and contacts the first segment of the first type of light emitting layer <NUM>-<NUM>, the first segment of the second type of light emitting layer <NUM>-<NUM>, and the first segment of the third type of light emitting layer <NUM>-<NUM> via the openings of the top isolation layer <NUM>.

<FIG> is a cross-sectional view illustrating a multi-color light emitting pixel unit <NUM>, according to an embodiment of the present disclosure. Referring to <FIG>, in the multi-color light emitting pixel unit <NUM>, the top of the third type of LED <NUM> is higher than that of the second type of LED <NUM>, while the height of the first type of LED is different from that of the second type of LED <NUM>.

<FIG> is a top view of the multi-color light emitting pixel unit <NUM>, according to an embodiment of the present disclosure. The multi-color light emitting pixel unit <NUM> can be the multi-color light emitting pixel unit <NUM> illustrated in <FIG> or the multi-color light emitting pixel unit <NUM> illustrated in <FIG> illustrates the arrangement of the three types of the LEDs <NUM>, <NUM>, and <NUM> in a pixel unit, but the present disclosure also includes other arrangements, such as a matrix. Herein, the size of the light emitting area of the third type of LED <NUM> is different from that of the first type of LED <NUM> and is different from that of the second type of the LED <NUM>. For example, the first type of LED <NUM> is a red LED, the second type of LED <NUM> is a green LED, and the third type of LED <NUM> is blue LED. The size of the light emitting area of each one of the first, second, and third type of LEDs <NUM>, <NUM>, and <NUM> can be determined according to the required light color to be emitted by the multi-color light emitting pixel unit <NUM>. When white light is required, the size of the light emitting area of the red LED is larger than that of the green LED, and the size of the light emitting area of the blue LED is larger than that of the green LED. As shown in <FIG>, the space between the red LED and the blue LED is larger than the space between the blue LED and the green LED; the space between the red LED and the green LED is larger than the space between the blue LED and the green LED, so as to achieve a better light emission effect.

Referring back to <FIG>, an isolation structure <NUM> is arranged between two of the first type of LED <NUM>, the second type of LED <NUM>, and the third type of LED <NUM>. The isolation structure is an isolation trench. The first type of LED <NUM>, the second type of LED <NUM>, and the third type of LED <NUM> are formed from a first metal layer <NUM>, a first type of light emitting layer <NUM>, a second metal layer <NUM>, a second type of light emitting layer <NUM>, a third metal layer <NUM>, and a third type of light emitting layer <NUM>. The first type of LED <NUM> and the second type of LED <NUM> in <FIG> are the same as the first type of LED <NUM> and the second type of LED <NUM> in <FIG>. Specifically, as illustrated in <FIG>, the first type of LED <NUM> includes, at least, a first segment of a first metal layer <NUM>-<NUM> and a first segment of a first type of light emitting layer <NUM>-<NUM> in an order from bottom to top. The second type of LED <NUM> includes, at least, a second segment of the first metal layer <NUM>-<NUM>, a second segment of the first type of light emitting layer <NUM>-<NUM>, a first segment of a second metal layer <NUM>-<NUM>, and a first segment of a second type of light emitting layer <NUM>-<NUM> in an order from bottom to top, and a first electrical connector <NUM>. The third type of LED <NUM> includes, at least, a third segment of the first metal layer <NUM>-<NUM>, a third segment of the first type of light emitting layer <NUM>-<NUM>, a second segment of the second metal layer <NUM>-<NUM>, a second segment of the second type of light emitting layer <NUM>-<NUM>, a first segment of a third metal layer <NUM>-<NUM>, and a first segment of a third type of light emitting layer <NUM>-<NUM> in an order from bottom to top, and a second electrical connector <NUM>. As shown in <FIG>, the first segment of the first metal layer <NUM>-<NUM>, the second segment of the first metal layer <NUM>-<NUM>, and the third segment of the first metal layer <NUM>-<NUM> are electrically connected with the substrate <NUM>. The first electrical connector <NUM> in the second type of LED <NUM> electrically connects the first segment of the second metal layer <NUM>-<NUM> with the second segment of the first metal layer <NUM>-<NUM>. The second electrical connector <NUM> in the third type of LED <NUM> electrically connects the first segment of the third metal layer <NUM>-<NUM> with the second segment of the second metal layer <NUM>-<NUM> and the third segment of the first metal layer <NUM>-<NUM>. The isolation structure <NUM> isolates the first segment of the first metal layer <NUM>-<NUM> in the first type of LED <NUM> from the second segment of the first metal layer <NUM>-<NUM> in the second type of LED <NUM> and the third segment of the first metal layer <NUM>-<NUM> in the third type of LED <NUM>, isolates the first segment of the first type of light emitting layer <NUM>-<NUM> in the first type of LED <NUM> from the second segment of the first type of light emitting layer <NUM>-<NUM> in the second type of LED <NUM> and the third segment of the first type of light emitting layer <NUM>-<NUM> in the third type of the LED <NUM>, isolates the first segment of the second metal layer <NUM>-<NUM> in the second type of LED <NUM> from the second segment of the second metal layer <NUM>-<NUM> in the third type of LED <NUM>, and isolates the first segment of the second type of light emitting layer <NUM>-<NUM> in the second type of LED <NUM> from the second segment of the second type of light emitting layer <NUM>-<NUM> in the third type of LED <NUM>. It should be noted that, the first electrical connector <NUM> is used to connect the second segment of the first type of light emitting layer <NUM>-<NUM> with the second segment of the first metal layer <NUM>-<NUM> in the second type of LED <NUM>, while the second electrical connector <NUM> is used to connect the second segment of the second type of light emitting layer <NUM>-<NUM> and the third segment of the first type of light emitting layer <NUM>-<NUM> with the third segment of the first metal layer <NUM>-<NUM> in the third type of LED <NUM>. Thus, in order to simplify the manufacturing process, in the same manner as <FIG>, the first electrical connector <NUM> further connects the second segment of first type of light emitting layer <NUM>-<NUM> with the second segment of the first metal layer <NUM>-<NUM>. That is, in the second type of LED <NUM>, the first electrical connector <NUM> connects the first segment of the second metal layer <NUM>-<NUM> and the second segment of the first type of light emitting layer <NUM>-<NUM> with the second segment of the first metal layer <NUM>-<NUM>. The second electrical connector <NUM> further connects the second segment of the second type of light emitting layer <NUM>-<NUM> with the third segment of the first metal layer <NUM>-<NUM>. That is, in the third type of LED <NUM>, the second electrical connector <NUM> connects the first segment of the third metal layer <NUM>-<NUM>, the second segment of the second type of light emitting layer <NUM>-<NUM>, and the second segment of the second metal layer <NUM>-<NUM> with the third segment of the first metal layer <NUM>-<NUM>. Alternatively, the second electrical connector <NUM> further connects the second segment of the second type of light emitting layer <NUM>-<NUM> and the third segment of the first type of light emitting layer <NUM>-<NUM> with the third segment of the first metal layer <NUM>-<NUM>. That is, in the third type of LED <NUM>, the second electrical connector <NUM> connects the first segment of the third metal layer <NUM>-<NUM>, the second segment of the second type of light emitting layer <NUM>-<NUM>, the second segment of the second metal layer <NUM>-<NUM>, and the third segment of the first type of light emitting layer <NUM>-<NUM> with the third segment of the first metal layer <NUM>-<NUM>. In addition, the bottom of the first electrical connector <NUM> and the bottom of the second electrical connector <NUM> separately and directly contact the substrate <NUM>, thereby simplifying the manufacturing process. It should be noted that the materials of the first electrical connector <NUM> and the second electrical connector <NUM> are formed of conductive metals. In an embodiment, the second electrical connector <NUM> is attached to and contacts the side wall surface of the third type of LED <NUM>.

In one embodiment, the first type of light emitting layer is a red light emitting layer, the second type of light emitting layer is a green light emitting layer, and the third type of light emitting layer is a blue light emitting layer, the first type of LED <NUM> is a red LED <NUM>, the second type of LED <NUM> is a green LED <NUM>, and the third type of LED <NUM> is a blue LED <NUM>. In the red LED <NUM>, an electrical voltage applied between the top transparent conductive layer <NUM> and the first segment of the first metal layer <NUM>-<NUM> is applied to the first segment of the red light emitting layer <NUM>-<NUM>. As a result, the first segment of the red light emitting layer <NUM>-<NUM> in the red LED <NUM> emits red light. In the green LED <NUM>, the first electrical connector <NUM> electrically connects the second segment of the red light emitting layer <NUM>-<NUM> with the second segment of the first metal layer <NUM>-<NUM>, such that an electrical voltage applied between the top transparent conductive layer <NUM> and the second segment of the first metal layer <NUM>-<NUM> is only applied to the first segment of the green light emitting layer <NUM>-<NUM>. As a result, only the first segment of the green light emitting layer <NUM>-<NUM> in the green LED <NUM> emits green light while the second segment of the red light emitting layer <NUM>-<NUM> in the green LED <NUM> does not emit light. In the third type of LED <NUM>, the second electrical connector <NUM> electrically connects the third segment of the red light emitting layer <NUM>-<NUM> and the second segment of the green light emitting layer <NUM>-<NUM> with the third segment of the first metal layer <NUM>-<NUM>, such that an electrical voltage applied between the top transparent conductive layer <NUM> and the third segment of the first metal layer <NUM>-<NUM> is only applied to the first segment of the blue light emitting layer <NUM>-<NUM>. As a result, only the first segment of the blue light emitting layer <NUM>-<NUM> in the blue LED <NUM> emits blue light while the third segment of the red light emitting layer <NUM>-<NUM> and the second segment of the green light emitting layer <NUM>-<NUM> in the blue LED <NUM> do not emit light.

Referring again to <FIG>, a top isolation layer <NUM> and a top transparent conductive layer <NUM> are arranged on the first type of LED <NUM>, the second type of LED <NUM>, and the third type of LED <NUM>. The top isolation layer <NUM> covers the first segment of the first type of light emitting layer <NUM>-<NUM>, the first segment of the second type of light emitting layer <NUM>-<NUM>, the first segment of the third type of light emitting layer <NUM>-<NUM>, and the exposed substrate <NUM>. Openings are arranged in the top isolation layer <NUM> to expose portions of the top surfaces of the first segment of the first type of light emitting layer <NUM>-<NUM>, the first segment of the second type of light emitting layer <NUM>-<NUM>, and the first segment of the third type of light emitting layer <NUM>-<NUM>. The top transparent conductive layer <NUM> covers the top isolation layer <NUM> and is formed in the openings of the top isolation layer <NUM>, thereby contacting the exposed top surface of the first segment of the first type of light emitting layer <NUM>-<NUM>, the exposed top surface of the first segment of the second type of light emitting layer <NUM>-<NUM>, and the exposed top surface of the first segment of the third type of light emitting layer <NUM>-<NUM>.

The detailed description of the substrate <NUM> in the multi-color light emitting pixel unit <NUM> with at least three types of LEDs corresponds to the description of <FIG> and will be not repeated herein. It should be noted that, the interconnection layer in the IC substrate <NUM> is electrically connected to the first type of LED <NUM>, the second type of LED <NUM>, and the third type of LED <NUM>. The driver circuit in the IC substrate <NUM> controls every LED separately.

In the multi-color light emitting pixel units <NUM> to <NUM> in <FIG>, one or more of the emitting layers <NUM>, <NUM>, and <NUM> can have micro-gap structures. For example, in the multi-color light emitting pixel unit <NUM> shown in <FIG>, the first type of light emitting layer <NUM> can have micro-gap structures, or the second type of light emitting layer <NUM> can have micro-gap structures, or both of the first type of light emitting layer <NUM> and the second type of light emitting layer <NUM> can have micro-gap structures. As another example, in the multi-color light emitting pixel unit <NUM> shown in <FIG>, the first type of light emitting layer <NUM> can have micro-gap structures, or the second type of light emitting layer <NUM> can have micro-gap structures, or the third type of light emitting layer <NUM> can have micro-gap structures, or both of the first type of light emitting layer <NUM> and the second type of light emitting layer <NUM> can have micro-gap structures, or both of the second type of light emitting layer <NUM> and the third type of light emitting layer <NUM> can have micro-gap structures, or both of the first type of light emitting layer <NUM> and the third type of light emitting layer <NUM> can have micro-gap structures, or all of the first type of light emitting layer <NUM>, the second type of light emitting layer <NUM> and the third type of light emitting layer <NUM> can have micro-gap structures. Herein, each one of the micro-gap structures in the multi-color light emitting pixel units <NUM> to <NUM> illustrated in <FIG> can be, but are not limited to, an air gap. The air gap is sealed. Preferably, the cross-sectional dimension of the air gap is not more than <NUM>, so as to release the stress in the light emitting layer and avoid curving of the light emitting layer without impacting the light emitting efficiency of the light emitting layer. Here, the cross-sectional dimension of the air gap can be the diameter of the cross section of the air gap, or the length or width of the cross section of the air gap.

<FIG> is a cross-sectional view illustrating a multi-color light emitting pixel unit <NUM>, according to an embodiment of the present disclosure. As shown in <FIG>, each one of the first type of light emitting layer <NUM>, the second type of light emitting layer <NUM>, and the third type of light emitting layer <NUM> can have a plurality of micro-gap structures <NUM>. Each one of the micro-gap structures <NUM> extends along a direction perpendicular to the substrate <NUM>, and penetrates the corresponding light emitting layer, such as the first type of light emitting layer <NUM>, the second type of light emitting layer <NUM>, or the third type of light emitting layer <NUM>. When multiple light emitting layers are used in an embodiment, the micro-gap structure <NUM> is arranged at least one light emitting layer, preferably in the top light emitting layer.

Still referring to <FIG>, the micro-gap structures <NUM> are staggered one on another in the multiple light emitting layers. That is, the micro-gap structures <NUM> in the first type of light emitting layer <NUM> are not vertically aligned with the micro-gap structures <NUM> in the second type of light emitting layer <NUM>, and the micro-gap structures <NUM> in the second type of light emitting layer <NUM> are not vertically aligned with the micro-gap structures <NUM> in the third type of light emitting layer <NUM>. In each one of the second type of LED <NUM> and the third type of LED <NUM>, the micro-gap structures in the first type of light emitting layer <NUM> is isolated and sealed between the second metal layer <NUM> at the top of the first type of light emitting layer <NUM> and the first metal layer <NUM> at the bottom thereof. In the third type of LED <NUM>, the micro-gap structures <NUM> in the second type of light emitting layer <NUM> is isolated and sealed between the third metal layer <NUM> at the top of the second light emitting layer <NUM> and the second metal layer <NUM> at the bottom thereof, and the micro-gap structures <NUM> in the third type of light emitting layer <NUM> is isolated and sealed between the top isolation layer <NUM> at the top of the third type of light emitting layer <NUM> and the third metal layer <NUM> at the bottom thereof.

In a similar manner, in a multi-color light emitting pixel unit including first to Mth types of LEDs in another embodiment of the present disclosure, the Mth type of LED has M light emitting layers and a metal layer is arranged at the bottom of each light emitting layer, wherein M is positive integer and greater than or equal to number two. In each one of the first to Mth type of LEDs, a top conductive layer (as an upper conductive layer) is arranged at the top of a top light emitting layer, so that the micro-gap structure in the top light emitting layer can be isolated and sealed between the top conductive layer and the metal layer at the bottom of the top light emitting layer. The micro-gap structure in every light emitting layer is isolated and sealed between the metal layers separately at the top and bottom of the relative light emitting layer.

In addition, similar to the multi-color light emitting pixel units <NUM> to <NUM> in <FIG>, a multi-color light emitting pixel unit according to another embodiment of the present disclosure includes a plurality of LEDs, including a first type of LED to a Mth type of LED. The Mth type of LED includes, at least, all of the light emitting layers and metals layers constructed in the (M-<NUM>)th type of LED, and an Mth light emitting layer and an Mth metal layer. On the basis thereof, the Mth type of LED has an (M-<NUM>)th electrical connector which connects to the Mth metal layer, the (M-<NUM>)th metal layer,. , and the first metal layer. Furthermore, the (M-<NUM>)th electrical connector can connect to the Mth metal layer, the (M-<NUM>)th type of light emitting layer, the (M-<NUM>)th metal layer,. , the first type of light emitting layer, and the first metal layer. The arrangement of the (M-<NUM>)th electrical connector can be referred to the description of the first electrical connector <NUM> in the <FIG>. The first to the (M-<NUM>)th electrical connectors connect the first to Mth metal layers, and the first to the (M-<NUM>)th electrical connectors can directly contact the substrate and the first metal layer. Herein, there is a difference from the first type of LED to the Mth type of LED. Additionally, every kind of LED can be selected from one of the red LED, green LED, blue LED, yellow LED, orange LED, purple LED or cyan LED. Herein, the different color LEDs are conventional LEDs, which can be known by those skilled in the art and will not be described herein. Furthermore, the first type of LED to the Mth type of LED are spaced apart on the same substrate. A top isolation layer covers the exposed surface of the substrate and that of the first to Mth types of LEDs. The top isolation layer of every type of LED has an opening thereof and a transparent conductive layer covers the surface of the top isolation layer and is filled in the opening, wherein the transparent conductive layer at the bottom of the opening electrically contacts the top light emitting layer of every type of LED. Referring to <FIG> and <FIG>, in the pixel unit having M types of LEDs, the size of the light emitting areas of the first to Mth types of LEDs are different from each other. According to the arrangement of the LEDs in the pixel unit, the size of the light emitting area of the first type of LED is larger than those of the other types of LEDs. Optionally, the first type of LED is a red LED which has the larger light emitting area than those of the other types of LEDs. Alternatively, the other types of LEDs at least include a green LED or a blue LED.

A multi-color micro-display panel is also provided according to an embodiment of the present disclosure. The micro-display panel includes a plurality of multi-color pixel units which are arranged in a matrix. The multi-color pixel units herein can be the LED pixel units mentioned above.

Hereafter combined with the drawings, the method of fabricating the multi-color light emitting pixel unit will be further described below.

<FIG> is a flow chart illustrating a the method of fabricating the multi-color light emitting pixel unit shown in <FIG>, according to an embodiment of the present disclosure. <FIG> are cross-sectional views illustrating structures formed in the steps illustrated in <FIG>, according to an embodiment of the present disclosure. Referring to <FIG>, the method of fabricating the multi-color light emitting pixel unit as shown in <FIG> includes the following steps.

In step S601, referring to <FIG>, a stack structure including a first metal layer <NUM>, a first type of light emitting layer <NUM>, a second metal layer <NUM>, and a second type of light emitting layer <NUM>, are formed on a substrate <NUM> from bottom to top. In other words, the first type of light emitting layer <NUM> and the second type of light emitting layer <NUM> are stacked on the substrate <NUM> from bottom to top. The first metal layer <NUM> is formed at the bottom of the first type of light emitting layer <NUM>. The second metal layer <NUM> is formed at the bottom of the second type of light emitting layer <NUM>. The second metal layer <NUM> is arranged between the first type of light emitting layer <NUM> and the second light emitting layer <NUM>.

More specifically, the substrate <NUM> can be, but not limited to, an IC substrate.

<FIG> is a flow chart illustrating the details of step S601 in <FIG>, according to an embodiment of the disclosure. <FIG> are cross-sectional views illustrating structures formed in the steps illustrated <FIG>, according to an embodiment of the present disclosure. Referring to <FIG>, step S601 further includes the following specific steps.

In step S101, referring to <FIG>, a first metal bonding layer M01 is formed on the substrate <NUM>, the first type of light emitting layer <NUM> is formed on a first base B1, and a second metal bonding layer M02 is formed on top of the first type of light emitting layer <NUM>.

More specifically, the first metal bonding layer M01 can be prepared by, but not limited to, physical vapor deposition, such as evaporation, sputtering, etc. The material of the first base B1 is designed according to the first type of light emitting layer <NUM>. For example, the first base B1 can be a gallium nitride (GaN) base. The first type of light emitting layer <NUM> can be formed by, but not limited to, epitaxial growth on the first base B1. The second metal bonding layer M02 can be prepared by, but not limited to, physical vapor deposition, such as evaporation.

In step S102, referring to <FIG> combined with <FIG>, the first base B1 is turned upside down so that the second metal bonding layer M02 faces the first metal bonding layer M01, and then the second metal bonding layer M02 is bonded with the first metal bonding layer M01 to form the first metal layer <NUM>.

In step S103, referring to <FIG> combined with <FIG>, the first base B1 is removed.

Herein, after the first base B1 is removed, referring to <FIG>, the step S103 can further includes: thinning the first type of light emitting layer <NUM>.

In addition, according to an embodiment, after the first base B1 is removed or the first type of light emitting layer <NUM> is thinned, and before the third metal bonding layer is formed, referring to <FIG>, step S103 can further include: forming micro-gap structures <NUM> in the first type of light emitting layer <NUM>. The micro-gap structures <NUM> are formed by, but not limited to, photolithography and etching. In photolithography, a lithography pattern is designed according to the dimension of the micro-gap structure <NUM>. According to an embodiment, a cross-sectional dimension of the micro-gap structure pattern is not more than <NUM>. Here, the cross-sectional dimension of the air gap can be the diameter of the cross section of the air gap, or the length or width of the cross section of the air gap.

In step S104, referring to <FIG>, a third metal bonding layer M03 is formed on the first type of light emitting layer <NUM>, the second type of light emitting layer <NUM> is formed on a second base B2, and a fourth metal bonding layer M04 is formed on top of the second type of light emitting layer <NUM>.

In step S105, referring to <FIG> combined with <FIG>, the second base B2 is turned upside down, so that the fourth metal bonding layer M04 faces the third metal bonding layer M03, and bonding the fourth metal bonding layer M04 with the third metal bonding layer M03 to form the second metal layer <NUM>.

In step S106, referring to <FIG> combined with <FIG>, the second base B2 is removed.

Herein, after the second base B2 is removed, referring to <FIG>, in step S106, the second type of light emitting layer <NUM> is thinned.

According to an embodiment, after the second base B2 is removed or the second type of light emitting layer <NUM> is thinned, referring to <FIG>, in the step S106, micro-gap structures <NUM> are formed in the second type of light emitting layer <NUM>. The micro-gap structures <NUM> are formed using a process similar to the process of forming the micro-gap structure <NUM> in the first type of light emitting layer <NUM>. Therefore, descriptions of the process of forming the micro-gap structures <NUM> in the second type of light emitting layer <NUM> will not be repeated.

Referring back to <FIG>, the process after step S601 according to the embodiment of the present disclosure will be further described hereafter.

In step S602, referring to <FIG>, the second type of light emitting layer <NUM> and the second metal layer <NUM> are patterned until a portion of the top of the first type of light emitting layer <NUM> is exposed, thereby forming a step structure made by the second type of light emitting layer <NUM> on the first type of light emitting layer <NUM>.

More specifically, the process of patterning the second type of light emitting layer <NUM> and the second metal layer 201can be performed by photolithography and plasma etching. The process of patterning the second type of light emitting layer <NUM> and the second metal layer <NUM> also includes: over etching the top of the first type of light emitting layer <NUM>. The parameters of the patterning process can be set according to actual needs, which will not be limited herein.

In step S603, referring to <FIG>, according to a pre-set first type of light emitting region A01 and a pre-set second type of light emitting region A02, the second type of light emitting layer <NUM>, the second metal layer <NUM>, the first type of light emitting layer <NUM>, and the first metal layer <NUM> are etched, so as to segment the first type of light emitting layer <NUM> in the first type of light emitting region A01 from the first type of light emitting layer <NUM> in the second type of light emitting region A02, and to segment the first metal layer <NUM> in the first type of light emitting region A01 from the first metal layer <NUM> in the second type of light emitting region A02. As a result of step S603, a first type of LED <NUM> including a first segment of the first metal layer <NUM>-<NUM> and a first segment of the first type of light emitting layer <NUM>-<NUM>, and a second type of LED <NUM> including a second segment of the first metal layer <NUM>-<NUM>, a second segment of the first type of light emitting layer <NUM>-<NUM>, a first segment of the second metal layer <NUM>-<NUM>, and a second segment of the second type of light emitting layer <NUM>-<NUM> are formed.

Herein, the process of etching the second type of light emitting layer <NUM>, the second metal layer <NUM>, the first type of light emitting layer <NUM>, and the first metal layer <NUM> is performed by photolithography and etching. The parameters of the process of etching can be set according to the actual needs.

According to an embodiment, as a result of step S603, a plurality of multi-color light emitting pixel units are segmented from each other according to a pre-set pixel unit array. In this manner, the light emitting diodes in a pixel unit and/or in an array of pixel units can be prepared by one segmenting step, which simplifies the process and decreases the production cost, especially facilitates the large-scale production.

In step S604, referring to <FIG>, a shared top electrode layer <NUM>, which functions as an extraction electrode of the second metal layer <NUM>, is formed on the tops of the first segment of the first type of light emitting layer <NUM>-<NUM> and the first segment of the second type of the light emitting layer <NUM>-<NUM> in the second type of light emitting region A02.

<FIG> is a flow chart illustrating the details of step S604 in <FIG>, according to an embodiment of the present disclosure. <FIG> are cross-sectional views illustrating structures formed in the steps illustrated <FIG>, according to an embodiment of the present disclosure. Referring to <FIG>, the specific process of the step S604 includes the following steps.

In step S401, referring to <FIG>, part of the first segment of the second type of light emitting layer <NUM>-<NUM> is removed, so as to expose part of the first segment of the second metal layer <NUM>-<NUM>.

In step S402, referring to <FIG>, the first electrical connector <NUM> is formed on the side wall and the top of the first segment of the second metal layer <NUM>-<NUM>, the sidewall of the second segment of the first type of light emitting layer <NUM>-<NUM>, and the sidewall of the second segment of the first metal layer <NUM>-<NUM> in the second type of light emitting region A02.

<FIG> are cross-sectional views illustrating structures formed in the step of fabricating the first electrical connector <NUM>, according to an embodiment of the present disclosure. In step S402, the first electrical connector <NUM> is formed by the following specific steps.

In step S4021, referring to <FIG> combined with <FIG>, a mask Y is formed to shield the region without the first electrical connector <NUM>, thereby exposing the top and the sidewall of the first segment of the second metal layer <NUM>-<NUM>, the sidewall of the second segment of the first type of light emitting layer <NUM>-<NUM>, and the sidewall of the second segment of the first metal layer <NUM>-<NUM> in the second type of light emitting region A02.

In step S4022, referring to <FIG>, a conductive material <NUM>' is deposited on the substrate <NUM> after completing the step S4021.

In step S4023, referring to <FIG> again, the mask Y and the conductive material <NUM>' on the mask Y are removed, so as to form the first electrical connector <NUM> on the top and the sidewall of the first segment of the second metal layer <NUM>-<NUM>, the sidewall of the second segment of the first type of light emitting layer <NUM>-<NUM>, and the sidewall of the second segment of the first metal layer <NUM>-<NUM> in the second type of light emitting region A02.

The process of fabricating the shared top electrode layer <NUM> will be further described hereinafter.

In step S403, referring to <FIG>, an isolation layer <NUM> is formed to cover the first type of light emitting region A01, the second type of light emitting region A02, and the surface of the exposed substrate <NUM>. The isolation layer <NUM> has openings on the first segment of the first type of light emitting layer <NUM>-<NUM> in the first type of light emitting region A01 and the first segment of the second type of light emitting layer <NUM>-<NUM> in the second type of light emitting region A02.

In step S404, referring to <FIG> again, the continuous shared top electrode layer <NUM> is formed on the whole substrate <NUM> after step S403, by, for example, deposition. The shared top electrode layer <NUM> formed in the openings is connected to the first segment of the first type of light emitting layer <NUM>-<NUM> in the first type of light emitting region A01 and the first segment of the second type of light emitting layer <NUM>-<NUM> in the second type of light emitting region A02.

<FIG> illustrates the structure of the multi-color light emitting pixel unit having micro-gap structures in the first type of light emitting layer <NUM> and the second type of light emitting layer <NUM>, according to an embodiment of the present disclosure.

<FIG> is a flow chart illustrating a method of fabricating the multi-color light emitting pixel unit <NUM> as shown in <FIG>, according to an embodiment of the present disclosure. <FIG> are cross-sectional views illustrating structures formed in the steps illustrated in <FIG>, according to an embodiment of the present disclosure. Referring to <FIG>, the method of fabricating the multi-color light emitting pixel unit <NUM> as shown in <FIG> includes the following steps.

In step S701, referring to <FIG>, a stack structure including a first metal layer <NUM>, a first type of light emitting layer <NUM>, a second metal layer <NUM>, a second type of light emitting layer <NUM>, a third metal layer <NUM>, and a third type of light emitting layer <NUM> is formed on a substrate <NUM> in an order from bottom to top. In other words, the first type of light emitting layer <NUM>, the second type of light emitting layer <NUM>, and the third type of light emitting layer <NUM> are stacked on the substrate <NUM> from bottom to top. The first metal layer <NUM> is formed at the bottom of the first type of light emitting layer <NUM>. The second metal layer <NUM> is formed at the bottom of the second type of light emitting layer <NUM>. The third metal layer <NUM> is formed at the bottom of the third type of light emitting layer <NUM>. The second metal layer <NUM> is arranged between the first type of light emitting layer <NUM> and the second type of light emitting layer <NUM>. The third metal layer <NUM> is arranged between the second type of light emitting layer <NUM> and the third type of light emitting layer <NUM>.

<FIG> is a flow chart illustrating the details of step S701 in <FIG>, according to an embodiment of the disclosure. Referring to <FIG> combined with <FIG>, step S701 further includes the following steps. It is noted that, the structures formed in the steps S801 to S809 of the present embodiment are not shown in drawings. But the steps S801 to S809 of the present embodiment can be understood by those of skill in the art with reference to the steps S101 to S109 of the embodiment described above.

In step S801, a first metal bonding layer is formed on the substrate <NUM>, the first type of light emitting layer <NUM> is formed on a first base, and a second metal bonding layer is formed on the top of the first type of light emitting layer <NUM>.

More specifically, the first metal bonding layer can be prepared by, but not limited to, physical vapor deposition, such as evaporation, sputtering, etc. The material of the first base is designed according to the first type of light emitting layer <NUM>. For example, the first base can be a gallium nitride (GaN) base. The first type of light emitting layer <NUM> can be made by, but not limited to, epitaxial growth on the first base. The second metal bonding layer can be prepared by, but not limited to, physical vapor deposition, such as evaporation.

In step S802, the first base is turned upside down so that the second metal bonding layer faces the first metal bonding layer, and the second metal bonding layer is bonded with the first metal bonding layer to form the first metal layer <NUM>.

In step S803, the first base is removed.

Herein, after the first base is removed, step S803 can further include: thinning the first type of light emitting layer <NUM>. In addition, after the first base is removed or the first type of light emitting layer <NUM> is thinned, and before the third metal bonding layer is formed, referring to <FIG>, step S803 can further include: forming micro-gap structures <NUM> in the first type of light emitting layer <NUM>. The micro-gap structures <NUM> are formed by, but not limited to, photolithography and etching. In photolithography, a lithography pattern is designed according to the dimension of the micro-gap structure <NUM>. According to an embodiment, a cross-sectional dimension of the micro-gap structure pattern is not more than <NUM>.

In step S804, a third metal bonding layer is formed on the first type of light emitting layer <NUM>, the second type of light emitting layer <NUM> is formed on a second base, and a fourth metal bonding layer is formed on the top of the second type of light emitting layer <NUM>.

In step S805, the second base is turned upside down so that the fourth metal bonding layer faces the third metal bonding layer and then the fourth metal bonding layer is bonded with the third metal bonding layer to form the second metal layer <NUM>.

In step S806, the second base is removed.

Herein, after the second base is removed, step S106 can further include: thinning the second type of light emitting layer <NUM>. In addition, after the second base is removed or the second type of light emitting layer <NUM> is thinned, referring to <FIG>, the step S106 further includes: forming micro-gap structures <NUM> in the second type of light emitting layer <NUM>. The micro-gap structure <NUM> can be formed using a process similar to the process of forming the micro-gap structure <NUM> described above. Therefore, description of the process of forming the micro-gap structure <NUM> will not be repeated.

In step S807, a fifth metal bonding layer is formed on the second type of light emitting layer <NUM>, the third type of light emitting layer <NUM> is formed on a third base, and a sixth metal bonding layer is formed on top of the third type of light emitting layer <NUM>.

In step S808, the third base is turned upside down so that the sixth metal bonding layer faces the fifth metal bonding layer and then the sixth metal bonding layer is bonded with the fifth metal bonding layer to form the third metal layer <NUM>.

In step S809, the third base is removed.

Herein, after the third base is removed, step S109 can further include: thinning the third type of light emitting layer <NUM>. In addition, after the third base is removed or the third type of light emitting layer <NUM> is thinned, referring to <FIG>, the step S109 further includes: forming micro-gap structures <NUM> in the third type of light emitting layer <NUM>. The micro-gap structure <NUM> can be formed using a process similar to the process of forming the micro-gap structure <NUM> described above. Therefore, description of the process of forming the micro-gap structure <NUM> will not be repeated.

<FIG> illustrates the micro-gap structures <NUM> in the first type of light emitting layer <NUM>, the second type of light emitting layer <NUM>, and the third type of light emitting layer <NUM>.

Referring back to <FIG>, the process after step S701 will be further described hereafter.

In step S702, referring to <FIG>, the third type of light emitting layer <NUM> and the third metal layer <NUM> are patterned until a portion of the top of the second type of light emitting layer <NUM> is exposed, thereby forming a step structure made by the third type of light emitting layer <NUM> on the second type of light emitting layer <NUM>.

More specifically, the step structure includes the third type of light emitting layer <NUM> and the third metal layer <NUM>. The process of patterning the third type of light emitting layer <NUM> and the third metal layer <NUM> also includes: over etching the top of the first type of light emitting layer <NUM>.

In step S703, referring to <FIG>, the second type of light emitting layer <NUM> and the second metal layer <NUM> are further patterned until a portion of the top of the first type of light emitting layer <NUM> is exposed, thereby forming a step structure made by the second type of light emitting layer <NUM> on the first type of light emitting layer <NUM>.

More specifically, the step structure is made by the second type of light emitting layer <NUM> and the second metal layer <NUM>. The patterning process can be performed by photolithography and plasma etching. The process of patterning the second type of light emitting layer <NUM> and the second metal layer <NUM> also includes: over etching the top of the first type of light emitting layer <NUM>. The parameters of the patterning process can be set according to the actual needs, which will not be limited herein.

In step S704, referring to <FIG>, according to a pre-set first type of light emitting region A01, a pre-set second type of light emitting region A02, and a pre-set third type of light emitting region A03, the third type of light emitting layer <NUM>, the third metal layer <NUM>, the second type of light emitting layer <NUM>, the second metal layer <NUM>, the first type of light emitting layer <NUM>, and the first metal layer <NUM> are etched, so as to segment the first type of light emitting layer <NUM> in the first type of light emitting region A01 from that in the second type of light emitting region A02 and from that in the third type of light emitting region A03, segment the first metal layer <NUM> in the first type of light emitting region A01 from that in the second type of light emitting region A02 and from that in the third type of light emitting region A03, segment the second type of light emitting layer <NUM> in the second type of light emitting region A02 from that in the third type of light emitting region A03, and segment the second metal layer <NUM> in the second type of light emitting region A02 from that in the third type of light emitting region A03. As a result of step S704, a first type of LED <NUM> including a first segment of the first metal layer <NUM>-<NUM> and a first segment of the first type of light emitting layer <NUM>-<NUM>, a second type of LED <NUM> including a second segment of the first metal layer <NUM>-<NUM>, a second segment of the first type of light emitting layer <NUM>-<NUM>, a first segment of the second metal layer <NUM>-<NUM>, and a first segment of the second type of light emitting layer <NUM>-<NUM>, and a third type of LED <NUM> including a third segment of the first metal layer <NUM>-<NUM>, a third segment of the first type of light emitting layer <NUM>-<NUM>, a second segment of the second metal layer <NUM>-<NUM>, a second segment of the second type of light emitting layer <NUM>-<NUM>, a first segment of the third metal layer <NUM>-<NUM>, and a first segment of the third type of light emitting layer <NUM>-<NUM>, are formed.

Herein, the etching process is performed by photolithography and etching process, the parameters of which can be set according to the actual needs.

According to an embodiment, as a result of step S704, a plurality of multi-color light emitting pixel units are segmented from each other according to a pre-set pixel unit array. Therefore, the light emitting diodes in a pixel unit and/or in an array of pixel units can be prepared by one segmenting step, which simplifies the process and decreases the production cost, especially facilitates the large-scale production.

In step S705, referring to <FIG>, a shared top electrode layer <NUM>, which functions as an extraction electrode of the first segment of the second metal layer <NUM>-<NUM> and an extraction electrode of the first segment of the third metal layer <NUM>-<NUM> is formed on the top of the first segment of the first type of light emitting layer <NUM>-<NUM>, the first segment of the second type of light emitting layer <NUM>-<NUM>, and the first segment in the third type of light emitting layer <NUM>-<NUM>.

<FIG> is a flow chart illustrating the details of step S705 in <FIG>, according to an embodiment of the present disclosure. <FIG> are cross-sectional views illustrating structures formed in the steps illustrated in <FIG>. Referring to <FIG>, step S705 further includes the following steps.

In step S501, referring to <FIG>, part of the first segment of the third type of light emitting layer <NUM>-<NUM> and part of the first segment of the second type of light emitting layer <NUM>-<NUM> are removed, so as to expose part of the first segment of second metal layer <NUM>-<NUM> and part of the first segment of the third metal layer <NUM>-<NUM>.

In step S502, referring to <FIG>, the first electrical connector <NUM> is formed on the side wall and the top of the first segment of the second metal layer <NUM>-<NUM>, the sidewall of the second segment of the first type of light emitting layer <NUM>-<NUM>, and the sidewall of the second segment of the first metal layer <NUM>-<NUM> in the second type of light emitting region A02, and a second electrical connector <NUM> is formed on the top and the sidewall of the first segment of the third metal layer <NUM>-<NUM>, the sidewall of the second segment of the second type of light emitting layer <NUM>-<NUM>, the sidewall of the second segment of the second metal layer <NUM>-<NUM>, the sidewall of the third segment of the first type of light emitting layer <NUM>-<NUM>, and the sidewall of the third segment of the first metal layer <NUM>-<NUM> in the third type of light emitting region A03.

More specifically, referring to <FIG>, the process of fabricating the first electrical connector <NUM> and the second electrical connector <NUM> further includes the following steps. It is noted that, the following steps S5021 to S5023 are not shown in drawings, but steps S5021 to S5023 can be understood by those of skill in the art with reference to steps S4021 to S4023 of the embodiment described above.

In step S5021, a mask is formed on the substrate <NUM> to shield the region without the first electrical connector <NUM>, and the second electrical connector <NUM>, thereby exposing the top and the sidewall of the first segment of the second metal layer <NUM>-<NUM>, the sidewall of the second segment of the first type of light emitting layer <NUM>-<NUM>, and the sidewall of the second segment of the first metal layer <NUM>-<NUM> in the second type of light emitting region A02, and exposing the top and the sidewall of the first segment of the third metal layer <NUM>-<NUM>, the sidewall of the second segment of the second type of light emitting layer <NUM>-<NUM>, the sidewall of the second segment of the second metal layer <NUM>-<NUM>, the sidewall of the third segment of the first type of light emitting layer <NUM>-<NUM>, and the sidewall of the third segment of the first metal layer <NUM>-<NUM> in the third type of light emitting region A03.

In step S5022, a conductive material is deposited on the substrate <NUM> after completing the step S5021.

In step S5023, referring to <FIG>, the mask and the conductive material on the mask are removed, so as to form the first electrical connector <NUM> on the top and the sidewall of first segment of the second metal layer <NUM>-<NUM>, the sidewall of the second segment of the first type of light emitting layer <NUM>-<NUM>, and the sidewall of the second segment of the first metal layer <NUM>-<NUM> in the second type of light emitting region A02, and form the second electrical connector <NUM> on the top and the sidewall of the first segment of the third metal layer <NUM>-<NUM>, the sidewall of the second segment of the second type of light emitting layer <NUM>-<NUM>, the sidewall of the second segment of the second metal layer <NUM>-<NUM>, the sidewall of the third segment of the first type of light emitting layer <NUM>-<NUM>, and the sidewall of the third segment of the first metal layer <NUM>-<NUM> in the third type of light emitting region A03.

In step S503, referring to <FIG>, an isolation layer <NUM> is formed to cover the first type of light emitting region A01, the second type of light emitting region A02, the third type of light emitting region A03, and the surface of the exposed substrate <NUM>. The isolation layer <NUM> has openings on the first segment of the first type of light emitting layer <NUM>-<NUM>, on the first segment of the second type of light emitting layer <NUM>-<NUM>, and on the first segment of the third type of light emitting layer <NUM>-<NUM>.

In step S504, referring to <FIG> again, the continuous shared top electrode layer <NUM> is formed on the entire substrate <NUM> after step S503. The shared top electrode layer <NUM> deposited in the openings is connected to the first segment of the first type of light emitting layer <NUM>-<NUM>, to the first segment of the second type of light emitting layer <NUM>-<NUM>, and to the first segment of the third type of light emitting layer <NUM>.

As mentioned above, in the method of fabricating the multi-color light emitting pixel unit according to the embodiments of the present disclosure, because the films deposition processes in every type of LED can be performed simultaneously, the LED can be prepared at the same time without being separately prepared, thereby simplifying the processes of fabricating the multi-color light emitting pixel unit and the micro-LED display panel and facilitating large-scale production. As a result of the fabrication method according to the embodiments of the present disclosure, different types of LEDs are arranged side by side on a same substrate with a short distance between each other. Therefore, the size of the LEDs and the display panel made of the LEDs can be reduced. For example, the size of each LED can be <NUM> × <NUM>. In addition, the tops of the different types of LEDs are not at the same horizontal plane. That is to say, the heights of the different types of LEDs are not the same, so as to expose the different types of light emitting layers on the top of different types of LEDs, thus ensuring the light emitting area and improving emission efficiency of every LED, and improving the integration of various LEDs. A micro-LED display panel formed by the pixel units of the embodiments of the present disclosure has a clear picture display and high resolution. Furthermore, since the electrical connector connects every metal layer in the Mth type of LED, the Mth type of light emitting layer, which is the top light emitting layer, in the Mth type of LED can emit light while the other light emitting layers in the Mth type of LED are short-circuited because the metal layers disposed on both sides of each one of the other light emitting layers are electrically connected to each other. For example, in the Mth type of LED, the first type of light emitting layer is short-circuited because the first type of metal layer and the second type of metal layer disposed on both sides of the first type of light emitting layer are electrically connected with each other; the second type of light emitting layer is short-circuited because the second type of metal layer and the third type of metal layer disposed on both sides of the second type of light emitting layer are electrically connected with each other; and so on. Therefore, various types of LEDs emit light separately without affecting each other. Furthermore, the micro-gap in the light emitting layer can release the stress in the interior of the light emitting layer and avoid warping thereof without influence on the light emitting efficiency of the light emitting layer, so as to improve the product yield.

Claim 1:
A multi-color light emitting pixel unit, comprising:
a first type of light emitting diode formed on a substrate (<NUM>) and including a first segment of a first metal layer (<NUM>) and a first segment of a first type of light emitting layer (<NUM>) in an order from bottom to top; and
a second type of light emitting diode formed on the substrate (<NUM>) and including a second segment of the first metal layer (<NUM>), a second segment of the first type of light emitting layer (<NUM>), a first segment of a second metal layer (<NUM>), a first segment of a second type of light emitting layer (<NUM>) in an order from bottom to top, and a first electrical connector (<NUM>) connecting the second segment of the first metal layer (<NUM>) and the first segment of the second metal layer (<NUM>),
wherein the second metal layer (<NUM>) is formed at the bottom of the second type of light emitting layer (<NUM>) and arranged between the first type of light emitting layer (<NUM>) and the second light emitting layer (<NUM>).