CN110034218A - A kind of miniature LED chip and display panel - Google Patents

Abstract

The invention discloses a micro LED chip and a display panel. The micro-LED chip includes: a substrate; a light-emitting layer group located on the substrate, at least including a first-type semiconductor layer, a light-emitting layer and a second-type semiconductor layer stacked and arranged; a first electrode and a second electrode, located on the substrate a side of the light-emitting layer group away from the substrate, the first electrode is electrically connected to the first type semiconductor layer, and the second electrode is electrically connected to the second type semiconductor layer; wherein, the first electrode is electrically connected to the second type semiconductor layer; One electrode is a ring-shaped electrode, the outer and inner sides of the first electrode have the same pattern, and the second electrode is located in the middle of the area surrounded by the inner side of the first electrode. The embodiments of the present invention reduce the difficulty of mass transfer of the micro LED chips by improving the electrode structure of the micro LED chips.

Description

A micro LED chip and display panel

technical field

Embodiments of the present invention relate to the technical field of micro LED displays, and in particular, to a micro LED chip and a display panel.

Background technique

Light Emitting Diode (LED) is widely used in technical fields such as lighting and display due to its advantages of small size, low power, long service life, high brightness and active light emission. Micro LED, also known as micro LED, mLED or μLED, is a new type of flat display technology. Micro LED displays have LED arrays of individual pixel elements. Compared with the currently widely used liquid crystal displays, micro LED displays have better contrast ratio , faster response speed, lower energy consumption.

Since the micro LEDs are individually manufactured in the form of chips, in the process of manufacturing the display device, a huge number of micro LED chips need to be transferred to the backplane. At present, the mass transfer methods of micro LED chips mainly include single pick and place transfer, fluid assembly, liquid surface self-assembly, electrostatic self-assembly, laser transfer and roller transfer. In view of the relatively small size of micro LED chips, it is not easy to transfer in all assembly processes, and considering the problem of electrode alignment of micro LED chips, the difficulty of mass transfer is greatly increased.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a micro LED chip and a display panel to reduce the difficulty of mass transfer of micro LED chips.

To achieve the above object, the present invention adopts the following technical solutions:

An embodiment of the present invention provides a micro LED chip, comprising:

substrate;

a light-emitting layer group located on the substrate, the light-emitting layer group at least comprising a first-type semiconductor layer, a light-emitting layer and a second-type semiconductor layer arranged in layers;

A first electrode and a second electrode are located on the side of the light-emitting layer group away from the substrate, the first electrode is electrically connected to the first type semiconductor layer, and the second electrode is connected to the second type semiconductor layer The semiconductor layers are electrically connected; wherein, the first electrode is a ring-shaped electrode, the pattern of the outer edge and the inner edge of the first electrode is the same, and the second electrode is located in the middle of the area surrounded by the inner edge of the first electrode.

In this technical solution, the first electrode is set as a ring-shaped electrode, and the second electrode is set in the middle of the area surrounded by the inner edge of the first electrode, that is, the first electrode is set around the second electrode, and the micro LED chip is transferred to a When the first electrode and the second electrode of the micro LED chip are matched with the backplane of the bonding electrode, on the one hand, it is only necessary to connect the first electrode and the second electrode with the corresponding positions on the backplane (inner to inner, outer to outer). ) of the bonding electrodes can be electrically connected without considering or distinguishing the polarities of the first electrode and the second electrode; on the other hand, when there is a rotational deviation of the micro LED chip, at least a part of the first electrode and the second electrode can be They are electrically connected to the bonding electrodes at the corresponding positions on the backplane, which avoids the excessive alignment deviation of one of the electrodes caused by the rotation deviation of the micro LED chip during the mass transfer process, and prevents the electrical contact area between the electrodes and the bonding electrodes. It is too small or even has no electrical contact, thereby avoiding poor electrical contact between the micro LED chip and the backplane. At the same time, due to the structure of the first electrode and the second electrode, the rotation deviation of the micro LED chip does not affect the first electrode and the second electrode and the backplane. The bonding electrodes at the corresponding positions on the board are electrically connected. Therefore, during the mass transfer process, the micro-LED chips can have rotational deviation without the need for deviation correction, which improves the problem that the spatial position of the micro-LED chips cannot be changed at will during the mass transfer process. And cause the problem of alignment deviation. In addition, since the patterns on the outer and inner sides of the first electrodes are the same, the uniformity of the circumferential distribution of the first electrodes can be improved, thereby improving the electrical contact area between the first electrodes and the bonding electrodes at the corresponding positions on the backplane. Uniformity, improve display effect. Therefore, the technical solution does not need to consider the polarities of the first electrode and the second electrode and the rotation deviation of the micro LED chip when transferring a large amount of micro LED chips, which improves the alignment deviation caused by the inability of the spatial position of the micro LED chip to change at will. This reduces the difficulty of mass transfer of micro-LED chips.

In the above micro LED chip, optionally, the outer edge and the inner edge of the first electrode are figures with a geometric center, and the geometric centers are coincident;

Preferably, the outer and inner sides of the first electrode are circular or regular polygons.

In this technical solution, the outer and inner sides of the first electrode are figures with geometric centers, and the geometric centers are coincident, so that the overall structure of the first electrode has high symmetry. The bonding electrodes at the corresponding positions on the backplane all have a large electrical contact area, which improves the electrical connection performance between the micro LED chip and the backplane, thereby improving the reliability of the display.

In the above-mentioned micro LED chip, optionally, the pattern formed by the second electrode has a geometric center, and the geometric center of the second electrode coincides with the geometric center of the outer edge or the inner edge of the first electrode.

In this technical solution, by setting the geometric center of the second electrode to coincide with the geometric center of the outer or inner edge of the first electrode, when there is a rotation deviation of the micro LED chip, the bonding between the first electrode and the second electrode and the corresponding position on the backplane The electrodes all have a larger electrical contact area, which further improves the electrical connection performance between the micro LED chip and the backplane, and effectively prevents poor electrical contact between the micro LED chip and the backplane.

In the above-mentioned micro LED chip, optionally, the pattern formed by the second electrode is the same as the pattern on the outer or inner side of the first electrode.

Based on the above technical solution, in the technical solution, on the basis that the geometric center of the second electrode coincides with the geometric center of the outer or inner edge of the first electrode, the pattern formed by the second electrode is set to be the same as the outer edge or the inner edge of the first electrode. The pattern on the inner side is the same. When one of the electrodes is completely aligned with the bonding electrode at the corresponding position on the backplane, the other electrode can be completely aligned with the bonding electrode at the corresponding position on the backplane, reducing the alignment. Difficulty, improve the efficiency of mass transfer.

In the micro LED chip described above, optionally, the second electrode is circular, and/or the outer edge or the inner edge of the first electrode is circular.

Based on the above technical solution, in this technical solution, on the basis that the geometric center of the second electrode coincides with the geometric center of the outer or inner edge of the first electrode, the second electrode is set to be circular, and/or the outer edge of the first electrode or The inner side is circular, that is, at least one of the outer or inner side of the second electrode and the first electrode is set to be circular, no matter how the micro LED chip rotates, at least one of the first electrode and the second electrode can always be guaranteed. It is completely aligned with the bonding electrode at the corresponding position on the backplane, which increases the electrical contact area between the first electrode and/or the second electrode and the bonding electrode at the corresponding position on the backplane, and further improves the connection between the micro LED chip and the backplane. The electrical connection performance can effectively prevent the poor electrical contact between the micro LED chip and the backplane.

In the above micro LED chip, optionally, the first electrode is an n-electrode, the second electrode is a p-electrode, the first-type semiconductor layer is an n-type semiconductor layer, and the second-type semiconductor layer is a p-type semiconductor layer, and the first-type semiconductor layer is located on the side of the light-emitting layer close to the substrate;

An annular groove is formed in the peripheral area of the micro LED chip, the annular groove penetrates the second type semiconductor layer and the light emitting layer and exposes the first type semiconductor layer, and the first electrode is formed in the exposed on the first type semiconductor layer.

In the above micro LED chip, optionally, the first electrode is a p-electrode, the second electrode is an n-electrode, the first-type semiconductor layer is a p-type semiconductor layer, and the second-type semiconductor layer is a p-type semiconductor layer. The semiconductor layer is an n-type semiconductor layer, and the second-type semiconductor layer is located on the side of the light-emitting layer close to the substrate;

A groove is formed in the middle region of the micro LED chip, the groove penetrates the first type semiconductor layer and the light emitting layer and exposes the second type semiconductor layer, and the second electrode is formed in the exposed on the second type semiconductor layer.

In the above-mentioned micro LED chip, optionally, the micro LED chip further includes a conductive filling layer, and the conductive filling layer is formed between the n-electrode and the n-type semiconductor layer.

In this technical solution, a conductive filling layer is formed between the n electrode and the n-type semiconductor layer, and the thickness of the conductive filling layer can be adjusted so that the heights of the first electrode and the second electrode can be adapted to the thickness of the bonding electrode at the corresponding position on the backplane. , so that the first electrode and the second electrode are in contact with the corresponding bonding electrodes at the same time, so as to prevent the micro LED chip from tilting after being bonded to the backplane, thereby avoiding affecting the display effect.

In the above micro LED chip, optionally, the first electrode and the second electrode are metal reflective electrodes.

In this technical solution, by setting the first electrode and the second electrode as metal reflective electrodes, the light emitted toward the first electrode or the second electrode can be returned to the light-emitting surface, thereby improving the luminous efficiency of the micro LED chip, and further reducing the reduction of the micro LED chip. power consumption.

Embodiments of the present invention further provide a display panel, including a backplane and a plurality of the micro LED chips described above;

The backplane is provided with bonding electrodes matching the first electrodes and the second electrodes of the micro LED chips, and the micro LED chips are bonded to the bonding electrodes through the first electrodes and the second electrodes. After the electrodes are bonded, they are flip-chipped on the backplane.

The beneficial effects of the present invention are as follows: in the micro LED chip and the display panel provided by the present invention, by setting the first electrode as a ring electrode, and setting the second electrode in the middle of the area surrounded by the inner edge of the first electrode, when the micro LED is arranged When the chip is transferred to a backplane with bonding electrodes that match the first and second electrodes of the micro LED chip, on the one hand, it is only necessary to place the first electrode and the second electrode with the corresponding positions on the backplane (internal). The bonding electrodes of the internal and external) can be electrically connected, and there is no need to consider or distinguish the polarities of the first electrode and the second electrode; on the other hand, when the micro LED chip has rotational deviation, the first electrode and the second electrode At least a part of each of them can be electrically connected to the bonding electrodes at the corresponding positions on the backplane, which avoids the excessive alignment deviation of one of the electrodes caused by the rotation deviation of the micro LED chip during the mass transfer process, and prevents the electrodes from bonding with the bonding electrodes. The electrical contact area of the electrodes is too small or even has no electrical contact, thereby avoiding poor electrical contact between the micro LED chip and the backplane. The second electrode is electrically connected to the bonding electrode at the corresponding position on the backplane. Therefore, during the mass transfer process, the micro-LED chip can have rotational deviation without the need for deviation correction, thereby improving the problem of the micro-LED chip during the mass transfer process. The spatial position cannot be changed at will, causing the problem of alignment deviation. In addition, since the patterns on the outer and inner sides of the first electrodes are the same, the uniformity of the circumferential distribution of the first electrodes can be improved, thereby improving the electrical contact area between the first electrodes and the bonding electrodes at the corresponding positions on the backplane. Uniformity, improve display effect. To sum up, the technical solution provided by the present invention does not need to consider the polarities of the first electrode and the second electrode and the rotation deviation of the micro LED chip when transferring a large amount of micro LED chips, which improves the fact that the spatial position of the micro LED chip cannot be arbitrarily determined. The problem of alignment deviation caused by the change, thereby reducing the difficulty of mass transfer of micro LED chips.

Description of drawings

The above and other features and advantages of the present invention will be more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments of the present invention with reference to the accompanying drawings, in which:

1 is a schematic top view of a conventional micro LED chip;

FIG. 2 is a schematic cross-sectional structure diagram along the A1-A2 direction in FIG. 1;

FIG. 3 is a schematic structural diagram of an existing micro LED chip during mass transfer;

FIG. 4 is a schematic structural diagram of the existing micro-LED chips rotating during mass transfer;

5 is a schematic top-view structure diagram of a micro LED chip provided by an embodiment of the present invention;

FIG. 6 is a schematic cross-sectional structure diagram along the B1-B2 direction in FIG. 5;

7 is a schematic top-view structure diagram of another micro LED chip provided by an embodiment of the present invention;

FIG. 8 is a schematic cross-sectional structure diagram along the C1-C2 direction in FIG. 7;

9 is a schematic structural diagram when the second electrode and the bonding electrode are aligned according to an embodiment of the present invention;

10 is a schematic cross-sectional structure diagram of another micro LED chip provided by an embodiment of the present invention;

FIG. 11 is a schematic cross-sectional structure diagram of a display panel provided by an embodiment of the present invention.

Detailed ways

The technical solutions of the present invention are further described below with reference to the accompanying drawings and through specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all structures related to the present invention.

FIG. 1 is a schematic top view of a conventional micro LED chip; FIG. 2 is a schematic cross-sectional structure of FIG. 1 along the A1-A2 direction. As shown in FIG. 1 and FIG. 2, the micro LED chip includes a substrate 1, a nucleation layer 2, an undoped GaN layer 3, an n-type GaN layer 4, a multiple quantum well layer 5, an electron blocking layer 6 and The p-type GaN layer 7, wherein part of the multiple quantum well layer 5, the electron blocking layer 6 and the p-type GaN layer 7 on the side of the micro LED chip are etched away, and p-type GaN layer 7 is formed on the unetched p-type GaN layer 7 Electrode 8, an n-electrode 9 is formed on the exposed n-type GaN layer 4 (both p-electrode 8 and n-electrode 9 are shown as rectangles in the figure, but can actually be of different shapes to distinguish electrode polarities). As mentioned in the background art, the micro LED chips in the prior art are manufactured separately. In the process of manufacturing the display device, a huge number of micro LED chips need to be transferred to the backplane. At this time, each micro LED chip The p-electrode 8 and n-electrode 9 must be bonded with the corresponding bonding electrodes on the backplane (the positions and polarities are corresponding), and the p-electrode 8 and n-electrode 9 of each micro LED chip are required to correspond to The bonding electrodes are aligned, and the p-electrode 8 and n-electrode 9 of each micro LED chip have no left-right deviation and rotation deviation, which greatly increases the difficulty of mass transfer. For example, referring to FIG. 3 , in the process of mass transfer (the transfer head 100 can be used for mass transfer), since the spatial position of the micro LED chip 10 cannot be changed at will, during electrode alignment, if the p-electrode 8 of some micro LED chips 10 If there is a left-right deviation from the n-electrode 9, and even the bonding electrode 201 on the backplane 200 cannot be aligned, it will cause abnormal display in some areas of the display panel; The p-electrode 8 and the n-electrode 9 are electrically connected to the bonding electrodes 201 of the corresponding polarities on the backplane 200 . For another example, referring to FIG. 4 , since the spatial position of the micro LED chip 10 cannot be freely changed during the mass transfer process, when the electrodes are aligned, if the p-electrode 8 and the n-electrode 9 of some of the micro-LED chips 10 have rotational deviations, the As a result, the electrical contact area between one of the electrodes (the n electrode 9 in the figure) and the corresponding bonding electrode 201 is very small (or even impossible to make electrical contact), resulting in poor electrical contact between the micro LED chip 10 and the backplane 200, resulting in abnormal display. . Therefore, in order to improve the display quality of the display panel, the existing micro LED chip 10 greatly increases the difficulty of mass transfer.

Based on the above reasons, an embodiment of the present invention provides a micro LED chip, the micro LED chip includes: a substrate; a light-emitting layer group located on the substrate, the light-emitting layer group at least includes a first-type semiconductor layer, a light-emitting layer and The second type semiconductor layer; the first electrode and the second electrode are located on the side of the light-emitting layer group away from the substrate, the first electrode is electrically connected to the first type semiconductor layer, and the second electrode is electrically connected to the second type semiconductor layer; wherein , the first electrode is a ring-shaped electrode, the pattern of the outer and inner sides of the first electrode is the same, and the second electrode is located in the middle of the area surrounded by the inner side of the first electrode. In the embodiment of the present invention, the first electrode is set as a ring electrode, and the second electrode is set in the middle of the area surrounded by the inner edge of the first electrode, so that there is no need to consider or distinguish the polarities of the first electrode and the second electrode and the micro LED The rotation deviation of the chip can ensure that at least a part of the first electrode and the second electrode are electrically connected to the bonding electrode at the corresponding position on the backplane, that is, no matter how the micro LED chip rotates, the first electrode and the second electrode are always connected to the backplane. The bonding electrodes at the corresponding positions are electrically connected to prevent the electrical contact area between one of the electrodes and the bonding electrodes from being too small or even no electrical contact, which improves the electrical connection performance between the micro LED chip and the backplane, thereby improving the process of mass transfer. The spatial position of the micro LED chip cannot be changed at will, causing the problem of alignment deviation. Thus, the embodiments of the present invention reduce the difficulty of mass transfer of micro LED chips.

It can be understood that the stacked arrangement of the multilayer film layers is only used to define the relative positional relationship of each film layer in the longitudinal direction, and is not used to limit the contact arrangement of the individual film layers, that is, in the stacked multilayer film layers, there are also Other film layers may be present. For example, in this embodiment, the light-emitting layer group at least includes a first-type semiconductor layer, a light-emitting layer, and a second-type semiconductor layer that are stacked in layers, between the first-type semiconductor layer and the light-emitting layer, or the second-type semiconductor layer and the light-emitting layer Other film layers, such as electron blocking layers, can also be arranged therebetween. The specific film layer can be determined according to the actual situation, which is not limited in the present invention.

The first electrode is an n electrode, and the second electrode is a p electrode. Correspondingly, the first type semiconductor layer is an n type semiconductor layer, and the second type semiconductor layer is a p type semiconductor layer; or the first electrode is a p electrode, and the second type semiconductor layer is a p type semiconductor layer. The electrode is an n-electrode, correspondingly, the first-type semiconductor layer is a p-type semiconductor layer, and the second-type semiconductor layer is an n-type semiconductor layer. The present invention does not limit the electrode polarities of the first electrode and the second electrode, as long as they match the polarities of the bonding electrodes on the backplane, and the first electrode is arranged around the second electrode.

Specifically, in an embodiment of the present invention, the first electrode is an n electrode, the second electrode is a p electrode, the first type semiconductor layer is an n type semiconductor layer, and the second type semiconductor layer is a p type semiconductor layer. FIG. 5 is a schematic top-view structural diagram of a micro LED chip provided by an embodiment of the present invention; FIG. 6 is a cross-sectional structural schematic diagram along the B1-B2 direction in FIG. 5 . As shown in Figure 5 and Figure 6, the micro LED chip includes:

substrate 101;

The first type semiconductor layer 102, the light emitting layer 103 and the second type semiconductor layer 104 are stacked and arranged, wherein the first type semiconductor layer 102 is located on the side of the light emitting layer 103 close to the substrate 101;

The first electrode 105 and the second electrode 106 are located on the side of the light-emitting layer group away from the substrate 101; the peripheral area of the micro LED chip is formed with an annular groove (corresponding to the area outside the circle dotted line in FIG. 5), and the annular groove runs through the second type The semiconductor layer 104 and the light emitting layer 103 and the first type semiconductor layer 102 are exposed, the first electrode 105 is formed on the exposed first type semiconductor layer 102 and the first electrode 105 is a ring electrode, and the first electrode 105 and the first type The semiconductor layer 102 is electrically connected; the second electrode 106 is formed on the second type semiconductor layer 104 surrounded by the annular groove, and the second electrode 106 is electrically connected to the second type semiconductor layer 104 .

It can be understood that FIG. 5 and FIG. 6 only schematically show the structure of an executable micro-LED chip, and the top-view outline of a single micro-LED chip can also be a triangle, a rectangle, or a hexagon, etc., depending on the actual situation. It is required to divide the top-view outline of a single micro LED chip through the corresponding shape of the cutting track; the graphics of the outer and inner edges of the first electrode, and the graphics of the second electrode can also be set to regular or irregular graphics according to the actual situation; in addition, Fig. 6 only shows the main film layer structure of the micro LED chip. The micro LED chip provided in the embodiment of the present invention may also include other functional film layers, which are not limited in the present invention.

Correspondingly, the preparation method of the micro LED chip may include: sequentially epitaxially growing the first type semiconductor layer 102 , the light emitting layer 103 and the second type semiconductor layer 104 on the wafer; The area of the micro LED chip is etched along the cutting track by plasma etching process to cut through the light-emitting layer group, so as to divide a plurality of micro LED chips; the photolithography process is used to form an annular groove pattern in the peripheral area of each micro LED chip , using a plasma etching process to etch the exposed light-emitting layer group to etch through the second-type semiconductor layer 104 and the light-emitting layer 103, exposing the first-type semiconductor layer 102, and forming an annular groove; A first electrode pattern is formed in the groove and a second electrode pattern is formed in the middle of the unetched second type semiconductor layer 104 (the photoresist at the first electrode pattern and the second electrode pattern is removed), and metal evaporation is used to form a second electrode pattern. The metal material is evaporated on the whole surface of the plating process, and the remaining photoresist is peeled off by a stripping process to make the metal on the photoresist fall off, thereby forming the annular first electrode 105 located in the annular groove and the middle of the second type semiconductor layer 104. The second electrode 106 .

In another embodiment of the present invention, the first electrode is a p-electrode, the second electrode is an n-electrode, the first-type semiconductor layer is a p-type semiconductor layer, and the second-type semiconductor layer is an n-type semiconductor layer. FIG. 7 is a schematic top-view structure diagram of another micro LED chip provided by an embodiment of the present invention; FIG. 8 is a schematic cross-sectional structure diagram along the C1-C2 direction in FIG. 7 . As shown in Figure 7 and Figure 8, the micro LED chip includes:

substrate 101;

The first type semiconductor layer 102, the light emitting layer 103 and the second type semiconductor layer 104 are stacked and arranged, wherein the second type semiconductor layer 104 is located on the side of the light emitting layer 103 close to the substrate 101;

The first electrode 105 and the second electrode 106 are located on the side of the light-emitting layer group away from the substrate 101; a groove is formed in the middle area of the micro LED chip (corresponding to the area within the circle dotted line in FIG. 7), and the groove runs through the first type The semiconductor layer 102 and the light emitting layer 103 and the second type semiconductor layer 104 are exposed, the second electrode 106 is formed on the exposed second type semiconductor layer 104, and the second electrode 106 is electrically connected to the second type semiconductor layer 104; the first The electrode 105 is formed on the first type semiconductor layer 102 surrounding the groove and the first electrode 105 is a ring electrode, and the first electrode 105 is electrically connected to the first type semiconductor layer 102 .

Optionally, in the above embodiments, the substrate may be a sapphire substrate, the n-type semiconductor layer may be an n-type GaN layer, the p-type semiconductor layer may be p-type GaN, and the light-emitting layer may be a single quantum well layer or a multi-quantum well layer. well layer. In addition, the first electrode and the second electrode can be metal reflective electrodes, and by setting the first electrode and the second electrode to be metal reflective electrodes, the light emitted toward the first electrode or the second electrode can be returned to the light-emitting surface, which improves the micro The luminous efficiency of the LED chip can further reduce the power consumption of the micro LED chip. Wherein, the metal reflective electrode may be a metal stack with reflective effect such as Cr/Al/Ti/Pt/Au.

In the technical solution of the above-mentioned embodiment, the first electrode is set as a ring electrode, and the second electrode is set in the middle of the area surrounded by the inner edge of the first electrode. When the electrode and the second electrode are matched on the backplane of the bonding electrode, on the one hand, it is only necessary to connect the first electrode and the second electrode respectively with the bonding electrode at the corresponding position (internal to internal, external to external) on the backplane. It can be connected without considering or distinguishing the polarities of the first electrode and the second electrode; on the other hand, when there is a rotational deviation of the micro LED chip, at least a part of the first electrode and the second electrode can be respectively corresponding to the backplane The electrical connection of the bonding electrodes at the position avoids the excessive alignment deviation of one of the electrodes due to the rotation deviation of the micro LED chip during the mass transfer process, and prevents the electrical contact area between the electrode and the bonding electrode from being too small or even no electrical contact. , thereby avoiding poor electrical contact between the micro LED chip and the backplane. At the same time, due to the structure of the first electrode and the second electrode, the rotation deviation of the micro LED chip does not affect the state of the first electrode and the second electrode and the corresponding position on the backplane. The fixed electrodes are electrically connected. Therefore, during the mass transfer process, the micro-LED chips can have rotational deviation without the need for deviation correction, thereby improving the alignment deviation caused by the fact that the spatial position of the micro-LED chips cannot be changed at will during the mass transfer process. question. In addition, since the patterns on the outer and inner sides of the first electrodes are the same, the uniformity of the circumferential distribution of the first electrodes can be improved, thereby improving the electrical contact area between the first electrodes and the bonding electrodes at the corresponding positions on the backplane. Uniformity, improve display effect. Therefore, the technical solution does not need to consider the polarities of the first electrode and the second electrode and the rotation deviation of the micro LED chip when transferring a large amount of micro LED chips, which improves the alignment deviation caused by the inability of the spatial position of the micro LED chip to change at will. This reduces the difficulty of mass transfer of micro-LED chips.

Optionally, the outer and inner sides of the first electrode are figures with geometric centers and the geometric centers are coincident; preferably, the outer and inner sides of the first electrodes are circles or regular polygons.

When the outer and inner edges of the first electrode are circular, no matter how large the rotation deviation of the micro LED chip is, the first electrode and the bonding electrode at the corresponding position on the backplane always have the same electrical contact area, and regardless of the micro LED chip In the case of the left and right deviation of the chip, the first electrode and the bonding electrode at the corresponding position on the backplane are always in full alignment and contact. Referring to FIG. 9 , without considering the left and right deviation of the micro LED chip, when the outer and inner sides of the first electrode 105 are regular polygons (square in the figure) and the micro LED chip has a rotation deviation, the first electrode 105 corresponds to Each side of the regular polygon and the bonding electrode 201 at the corresponding position on the backplane have at least two electrical contact surfaces Z; the rotation angle of the micro LED chip is When an integer multiple of , the first electrode and the bonding electrode at the corresponding position on the backplane are always in complete alignment and contact, where n is the number of sides of a regular polygon. For example, when the regular polygon is a square (regular quadrilateral), when the micro LED chip is rotated by 90°, 180° and 270°, the first electrode and the bonding electrode at the corresponding position on the backplane are always in full alignment and contact.

In this technical solution, the outer and inner sides of the first electrode are figures with geometric centers, and the geometric centers are coincident, so that the overall structure of the first electrode has high symmetry. The bonding electrodes at the corresponding positions on the backplane always have a larger electrical contact area, which improves the electrical connection performance between the micro LED chip and the backplane, thereby improving the reliability of the display.

In the above-mentioned micro LED chip, optionally, the pattern formed by the second electrode has a geometric center, and the geometric center of the second electrode coincides with the geometric center of the outer edge or the inner edge of the first electrode.

When there is a rotation deviation of the micro LED chip, it basically rotates with the geometric center of the outer or inner edge of the first electrode as the rotation center. If they overlap, the electrical contact area between the second electrode and the bonding electrode at the corresponding position on the backplane will be smaller as the rotation deviation or rotation angle is different, and there is a risk of poor contact between the micro LED chip and the backplane. Based on this, in this technical solution, by setting the geometric center of the second electrode to coincide with the geometric center of the outer or inner edge of the first electrode, when there is a rotation deviation of the micro LED chip, the first electrode and the second electrode are in the corresponding position on the backplane. All of the bonding electrodes have a larger electrical contact area, which further improves the electrical connection performance between the micro LED chip and the backplane, and effectively prevents poor electrical contact between the micro LED chip and the backplane.

Further, the pattern formed by the second electrode is the same as the pattern on the outer or inner side of the first electrode.

Exemplarily, the pattern formed by the second electrode is the same regular polygon as the pattern on the outer or inner side of the first electrode, and the rotation angle of the micro LED chip is When an integer multiple of , the first electrode and the second electrode are completely aligned and contacted with the bonding electrodes at corresponding positions on the backplane, where n is the number of sides of a regular polygon. Furthermore, when aligning one of the electrodes of the micro LED chip, the other electrode of the micro LED chip is automatically aligned.

Therefore, based on the above technical solution, in the technical solution, on the basis that the geometric center of the second electrode coincides with the geometric center of the outer or inner edge of the first electrode, the pattern formed by the second electrode is set to be the same as that of the first electrode. The patterns on the outside or inside are the same. When one of the electrodes is completely aligned with the bonding electrode at the corresponding position on the backplane, the other electrode can be guaranteed to be completely aligned with the bonding electrode at the corresponding position on the backplane. Align the difficulty and improve the efficiency of mass transfer.

Optionally, the second electrode is circular, and/or the outer edge or the inner edge of the first electrode is circular.

Based on the above technical solution, in this technical solution, on the basis that the geometric center of the second electrode coincides with the geometric center of the outer or inner edge of the first electrode, the second electrode is set to be circular, and/or the outer edge of the first electrode or The inner side is circular, that is, at least one of the outer or inner side of the second electrode and the first electrode is set to be circular, no matter how the micro LED chip rotates, at least one of the first electrode and the second electrode can always be guaranteed. It is completely aligned with the bonding electrode at the corresponding position on the backplane, which increases the electrical contact area between the first electrode and/or the second electrode and the bonding electrode at the corresponding position on the backplane, and further improves the connection between the micro LED chip and the backplane. The electrical connection performance can effectively prevent the poor electrical contact between the micro LED chip and the backplane.

Further, based on the above technical solution, in another embodiment of the present invention, as shown in FIG. 10 , the micro LED chip may further include a conductive filling layer 107 formed on the n-electrode (the first electrode in the figure). 105) and the n-type semiconductor layer (the first type semiconductor layer 102 in the figure), the n-electrode is electrically connected to the n-type semiconductor layer through the conductive filling layer 107.

Exemplarily, the conductive filling layer 107 can be prepared by the same process as the above-mentioned preparation of the first electrode and the second electrode, that is, the conductive filling layer 107 is formed by a photolithography process, a metal evaporation process and a lift-off process, respectively. The material of the conductive filling layer 107 Can be Al\Au.

In this technical solution, a conductive filling layer is formed between the n electrode and the n-type semiconductor layer, and the thickness of the conductive filling layer can be adjusted so that the heights of the first electrode and the second electrode can be adapted to the thickness of the bonding electrode at the corresponding position on the backplane. , so that the first electrode and the second electrode are in contact with the corresponding bonding electrodes at the same time, so as to prevent the micro LED chip from tilting after being bonded to the backplane, thereby avoiding affecting the display effect.

Optionally, based on the above technical solution, with continued reference to FIG. 10 , the micro LED chip may further include a transparent metal oxide layer 108 and a protective layer 109 . The transparent metal oxide layer 108 and the protective layer 109 are stacked, the transparent metal oxide layer 108 covers the surface of the second type semiconductor layer 104 , and the second electrode 106 is in electrical contact with the transparent metal oxide layer 108 through via holes.

Exemplarily, the ITO layer can be fabricated by means of evaporation or sputtering, and the ITO on the second type semiconductor layer 104 is retained through a photolithography process and wet etching to form a transparent metal oxide layer 108 as the second electrode. The ohmic contact of 106; the stacked structure of TiO ₂ and SiO ₂ is evaporated by PVD, or the SiO ₂ or SiN film layer is grown by peCVD to form the protective layer 109, and then the photolithography process and etching (dry method or Wet method, etching part of the protective layer 109, exposing the conductive filling layer 107 and the transparent metal oxide layer 108, to subsequently form the first electrodes 105 and 105 in electrical contact with the conductive filling layer 107 and the transparent metal oxide layer 108 respectively The second electrode 106 .

In addition, an embodiment of the present invention further provides a display panel. As shown in FIG. 11 , the display panel includes a backplane 300 and a plurality of micro LED chips 20 provided in any of the above-mentioned embodiments; The first electrode 105 and the second electrode 106 of the LED chip 20 match the bonding electrode 301 (the shape, size and position are exactly the same), and the micro LED chip 20 is bonded to the bonding electrode 301 through the first electrode 105 and the second electrode 106 After being fixed, it is flip-mounted on the backplane 300 . The display panel can be applied to display devices such as mobile phones, computers, televisions, and smart wearable display devices, which are not particularly limited in this embodiment of the present invention.

The display panel provided by the embodiment of the present invention includes the micro LED chip provided by the embodiment of the present invention, and has the same functions and effects, which will not be repeated here.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. a miniature LED chip, is characterized in that, comprises: substrate; a light-emitting layer group located on the substrate, the light-emitting layer group at least comprising a first-type semiconductor layer, a light-emitting layer and a second-type semiconductor layer arranged in layers; A first electrode and a second electrode are located on the side of the light-emitting layer group away from the substrate, the first electrode is electrically connected to the first type semiconductor layer, and the second electrode is connected to the second type semiconductor layer The semiconductor layers are electrically connected; wherein, the first electrode is a ring-shaped electrode, the pattern of the outer edge and the inner edge of the first electrode is the same, and the second electrode is located in the middle of the area surrounded by the inner edge of the first electrode. 2 . The micro LED chip according to claim 1 , wherein the outer edge and the inner edge of the first electrode are figures with geometric centers, and the geometric centers are coincident; 3 . Preferably, the outer and inner sides of the first electrode are circular or regular polygons. 3 . The micro LED chip according to claim 2 , wherein the pattern formed by the second electrode has a geometric center, and the geometric center of the second electrode is connected to the outer edge or the inner edge of the first electrode. 4 . the geometric centers of . 4 . The micro LED chip according to claim 3 , wherein the pattern formed by the second electrode is the same as the pattern on the outer side or the inner side of the first electrode. 5 . 5 . The micro LED chip according to claim 3 , wherein the second electrode is circular, and/or the outer edge or the inner edge of the first electrode is circular. 6 . 6 . The micro LED chip according to claim 1 , wherein the first electrode is an n-electrode, the second electrode is a p-electrode, the first-type semiconductor layer is an n-type semiconductor layer, and the The second-type semiconductor layer is a p-type semiconductor layer, and the first-type semiconductor layer is located on the side of the light-emitting layer close to the substrate; An annular groove is formed in the peripheral area of the micro LED chip, the annular groove penetrates the second type semiconductor layer and the light emitting layer and exposes the first type semiconductor layer, and the first electrode is formed in the exposed on the first type semiconductor layer. 7 . The micro LED chip according to claim 1 , wherein the first electrode is a p-electrode, the second electrode is an n-electrode, and the first-type semiconductor layer is a p-type semiconductor layer, 8 . The second-type semiconductor layer is an n-type semiconductor layer, and the second-type semiconductor layer is located on the side of the light-emitting layer close to the substrate; A groove is formed in the middle region of the micro LED chip, the groove penetrates the first type semiconductor layer and the light emitting layer and exposes the second type semiconductor layer, and the second electrode is formed in the exposed on the second type semiconductor layer. 8 . The micro LED chip according to claim 6 , wherein the micro LED chip further comprises a conductive filling layer, and the conductive filling layer is formed between the n electrode and the n-type semiconductor layer. 9 . . 9 . The micro LED chip according to claim 1 , wherein the first electrode and the second electrode are metal reflective electrodes. 10 . 10. A display panel, characterized by comprising a backplane and a plurality of micro-LED chips according to any one of claims 1-9; The backplane is provided with bonding electrodes matching the first electrodes and the second electrodes of the micro LED chips, and the micro LED chips are bonded to the bonding electrodes through the first electrodes and the second electrodes. After the electrodes are bonded, they are flip-chipped on the backplane.