CN110034218B - Miniature LED chip and display panel - Google Patents
Miniature LED chip and display panel Download PDFInfo
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- CN110034218B CN110034218B CN201910319717.5A CN201910319717A CN110034218B CN 110034218 B CN110034218 B CN 110034218B CN 201910319717 A CN201910319717 A CN 201910319717A CN 110034218 B CN110034218 B CN 110034218B
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- H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
- H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
- H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/36—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
- H01L33/38—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes with a particular shape
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Abstract
The invention discloses a micro LED chip and a display panel. Wherein, miniature LED chip includes: a substrate; the light emitting layer group is positioned on the substrate and at least comprises a first type semiconductor layer, a light emitting layer and a second type semiconductor layer which are arranged in a laminated mode; the first electrode and the second electrode are positioned on one side, far away from the substrate, of the light-emitting layer group, the first electrode is electrically connected with the first type semiconductor layer, and the second electrode is electrically connected with the second type semiconductor layer; the first electrode is a ring electrode, the outer edge and the inner edge of the first electrode are identical in graph, and the second electrode is located in the middle of the area surrounded by the inner edge of the first electrode. According to the embodiment of the invention, the electrode structure of the micro LED chip is improved, so that the difficulty of mass transfer of the micro LED chip is reduced.
Description
Technical Field
The embodiment of the invention relates to the technical field of micro LED display, in particular to a micro LED chip and a display panel.
Background
Light Emitting Diodes (LEDs) are widely used in the technical fields of illumination and display due to their advantages of small size, low power, long service life, high brightness, and active Light emission. The micro LED, also known as micro LED, mLED or mu LED, is a novel flat display technology, and the micro LED display is provided with an LED array of single pixel elements, and compared with the liquid crystal display widely applied at present, the micro LED display has better contrast, faster response speed and lower energy consumption.
Since the micro LED is separately manufactured in the form of a chip, a huge amount of micro LED chips need to be transferred onto a back sheet in the process of manufacturing a display device. At present, the mass transfer mode of micro LED chips mainly includes single pick-and-place transfer, fluid assembly, liquid surface self-assembly, electrostatic self-assembly, laser transfer printing, and roller transfer printing. In view of the small size of the micro LED chip, the transfer is not easy to realize in all assembling processes, and the difficulty of mass transfer is greatly increased by considering the problem of electrode alignment of the micro LED chip.
Disclosure of Invention
In view of the above, the present invention is directed to a micro LED chip and a display panel, so as to reduce the difficulty of mass transfer of the micro LED chip.
In order to achieve the purpose, the invention adopts the following technical scheme:
the embodiment of the invention provides a micro LED chip, which comprises:
a substrate;
the light-emitting layer group is positioned on the substrate and at least comprises a first type semiconductor layer, a light-emitting layer and a second type semiconductor layer which are arranged in a stacked mode;
the first electrode and the second electrode are positioned on one side, far away from the substrate, of the light-emitting layer group, the first electrode is electrically connected with the first type semiconductor layer, and the second electrode is electrically connected with the second type semiconductor layer; the first electrode is a ring electrode, the outer edge and the inner edge of the first electrode are identical in graph, and the second electrode is located in the middle of the area surrounded by the inner edge of the first electrode.
According to the technical scheme, the first electrode is set to be the annular electrode, the second electrode is arranged in the middle of the area surrounded by the inner edge of the first electrode, namely the first electrode is arranged around the second electrode, when the micro LED chip is transferred to the back plate with the bonding electrodes matched with the first electrode and the second electrode of the micro LED chip, on one hand, the first electrode and the second electrode are only required to be electrically connected with the bonding electrodes at corresponding positions (inner to outer) on the back plate respectively, and the polarities of the first electrode and the second electrode do not need to be considered or distinguished; on the other hand, when the micro LED chip has rotation deviation, at least one part of the first electrode and the second electrode can be respectively and electrically connected with the bonding electrode at the corresponding position on the back plate, thereby avoiding overlarge alignment deviation of one electrode caused by the rotation deviation of the micro LED chip in the process of transferring a huge amount, preventing the electrical contact area between the electrode and the bonding electrode from being too small or even having no electrical contact, further avoiding the poor electrical contact between the micro LED chip and the back plate, and simultaneously, due to the structure of the first electrode and the second electrode, the rotation deviation of the micro LED chip does not influence the electric connection between the first electrode and the second electrode and the bonding electrode at the corresponding position on the back plate, therefore, rotational misalignment of the micro LED chips can occur during bulk transfer without correction of the misalignment, and the problem of contraposition deviation caused by the fact that the space position of the micro LED chip cannot be randomly changed in the process of mass transfer is solved. In addition, because the patterns of the outer edge and the inner edge of the first electrode are the same, the circumferential distribution uniformity of each first electrode can be improved, so that the uniformity of the electric contact area of each first electrode and the bonding electrode at the corresponding position on the back plate can be improved, and the display effect is improved. Therefore, the technical scheme 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 the micro LED chip is transferred in a huge amount, the problem of contraposition deviation caused by the fact that the space position of the micro LED chip cannot be changed randomly is solved, and the difficulty in transferring the huge amount of the micro LED chip is further reduced.
Optionally, the outer edge and the inner edge of the first electrode are in a pattern with a geometric center, and the geometric centers are overlapped;
preferably, the outer edge and the inner edge of the first electrode are circular or regular polygonal.
In the technical scheme, the outer edge and the inner edge of the first electrode are coincident with the figure with the geometric center and the geometric center, so that the overall structure of the first electrode has higher symmetry, when the micro LED chip has rotation deviation, the bonding electrodes at the corresponding positions on the first electrode and the back plate all have larger electric contact area, the electric connection performance of the micro LED chip and the back plate is improved, and the display reliability is further improved.
As above, 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.
According to the technical scheme, the geometric center of the second electrode is overlapped with the geometric center of the outer edge or the inner edge of the first electrode, when the micro LED chip has rotation deviation, the first electrode, the second electrode and the bonding electrode at the corresponding position on the back plate have larger electric contact area, the electric connection performance of the micro LED chip and the back plate is further improved, and the micro LED chip is effectively prevented from being in poor electric contact with the back plate.
As described above, optionally, the second electrode has the same pattern as the outer edge or the inner edge of the first electrode.
Based on the technical scheme, on the basis that the geometric center of the second electrode is superposed with the geometric center of the outer edge or the inner edge of the first electrode, the graph formed by the second electrode is set to be the same as the graph of the outer edge or the inner edge of the first electrode, when one of the electrodes is completely aligned with the bonding electrode at the corresponding position on the back plate, the complete alignment of the other electrode and the bonding electrode at the corresponding position on the back plate can be ensured, the alignment difficulty is reduced, and the mass transfer efficiency is improved.
As 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 technical scheme, on the basis that the geometric center of the second electrode is superposed with the geometric center of the outer edge or the inner edge of the first electrode, the second electrode is set to be circular, and/or the outer edge or the inner edge of the first electrode is circular, namely at least one of the outer edge or the inner edge of the second electrode and the inner edge of the first electrode is set to be circular, so that no matter how the micro LED chip rotates, the complete alignment of at least one of the first electrode and the second electrode and the bonding electrode at the corresponding position on the back plate can be always ensured, the electric contact area of the first electrode and/or the second electrode and the bonding electrode at the corresponding position on the back plate is increased, the electric connection performance of the micro LED chip and the back plate is further improved, and the micro LED chip and the back plate are effectively prevented from being in poor electric contact.
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, 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 through the second type semiconductor layer and the light emitting layer and exposes the first type semiconductor layer, and the first electrode is formed on the exposed first type semiconductor layer.
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, the second type semiconductor layer is an n-type semiconductor layer, and the second type semiconductor layer is located on a side of the light-emitting layer close to the substrate;
the middle area of the micro LED chip is provided with a groove, the groove penetrates through the first type semiconductor layer and the luminous layer and exposes the second type semiconductor layer, and the second electrode is formed on the exposed second type semiconductor layer.
The micro LED chip optionally further comprises a conductive filling layer formed between the n-electrode and the n-type semiconductor layer.
This technical scheme is through forming the electrically conductive filling layer between n electrode and n type semiconductor layer, and the thickness of electrically conductive filling layer is adjusted to the accessible, makes the thickness of the nation decides the electrode that corresponds the position on the highly adaptation backplate of first electrode and second electrode to make first electrode and second electrode and the nation who corresponds decide the electrode simultaneous contact, avoid miniature LED chip nation to take place the slope after on the backplate, and then avoid influencing the display effect.
Optionally, the first electrode and the second electrode are metal reflective electrodes.
According to the technical scheme, the first electrode and the second electrode are metal reflecting electrodes, light emitted towards the first electrode or the second electrode can be returned to the light emitting surface, the light emitting efficiency of the micro LED chip is improved, and the power consumption of the micro LED chip can be reduced.
The embodiment of the invention also provides a display panel, which comprises a back plate and a plurality of the miniature LED chips;
the back plate is provided with a bonding electrode matched with a first electrode and a second electrode of the micro LED chip, and the micro LED chip is inversely installed on the back plate after being bonded by the first electrode and the second electrode and the bonding electrode.
The invention has the beneficial effects that: according to the micro LED chip and the display panel provided by the invention, the first electrode is set to be the annular electrode, the second electrode is arranged in the middle of the area surrounded by the inner edge of the first electrode, and when the micro LED chip is transferred to the back plate with the bonding electrodes matched with the first electrode and the second electrode of the micro LED chip, on one hand, the first electrode and the second electrode are respectively and electrically connected with the bonding electrodes at corresponding positions (inner-inner and outer-outer) on the back plate, and the polarities of the first electrode and the second electrode do not need to be considered or distinguished; on the other hand, when the micro LED chip has rotation deviation, at least one part of the first electrode and the second electrode can be respectively and electrically connected with the bonding electrode at the corresponding position on the back plate, thereby avoiding overlarge alignment deviation of one electrode caused by the rotation deviation of the micro LED chip in the process of transferring a huge amount, preventing the electrical contact area between the electrode and the bonding electrode from being too small or even having no electrical contact, further avoiding the poor electrical contact between the micro LED chip and the back plate, and simultaneously, due to the structure of the first electrode and the second electrode, the rotation deviation of the micro LED chip does not influence the electric connection between the first electrode and the second electrode and the bonding electrode at the corresponding position on the back plate, therefore, rotational misalignment of the micro LED chips can occur during bulk transfer without correction of the misalignment, and the problem of contraposition deviation caused by the fact that the space position of the micro LED chip cannot be randomly changed in the process of mass transfer is solved. In addition, because the patterns of the outer edge and the inner edge of the first electrode are the same, the circumferential distribution uniformity of each first electrode can be improved, so that the uniformity of the electric contact area of each first electrode and the bonding electrode at the corresponding position on the back plate can be improved, and the display effect is improved. In summary, according to the technical scheme provided by the invention, the polarities of the first electrode and the second electrode and the rotation deviation of the micro LED chip do not need to be considered when the micro LED chip is transferred in a huge amount, so that the problem of alignment deviation caused by the fact that the spatial position of the micro LED chip cannot be changed at will is solved, and the difficulty in transferring the huge amount of the micro LED chip is further reduced.
Drawings
The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:
fig. 1 is a schematic top view of a conventional micro LED chip;
FIG. 2 is a schematic sectional view taken along the line A1-A2 in FIG. 1;
FIG. 3 is a schematic structural diagram of a conventional micro LED chip during mass transfer;
FIG. 4 is a schematic diagram of a conventional micro LED chip rotating during mass transfer;
fig. 5 is a schematic top view of a micro LED chip according to an embodiment of the present invention;
FIG. 6 is a schematic cross-sectional view taken along line B1-B2 in FIG. 5;
fig. 7 is a schematic top view of another micro LED chip according to an embodiment of the present invention;
FIG. 8 is a schematic cross-sectional view taken along line C1-C2 in FIG. 7;
FIG. 9 is a schematic structural diagram of a second electrode and a bonding electrode in alignment according to an embodiment of the present invention;
fig. 10 is a schematic cross-sectional view of another micro LED chip according to an embodiment of the present invention;
fig. 11 is a schematic cross-sectional structure diagram of a display panel according to an embodiment of the present invention.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic top view of a conventional micro LED chip; FIG. 2 is a schematic sectional view taken along the line A1-A2 in FIG. 1. As shown in fig. 1 and 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 multi-quantum well layer 5, an electron blocking layer 6 and a p-type GaN layer 7, which are sequentially stacked, wherein a portion of the multi-quantum well layer 5, the electron blocking layer 6 and the p-type GaN layer 7 on one side of the micro LED chip is etched away, a p-electrode 8 is formed on the p-type GaN layer 7 which is not etched, and an n-electrode 9 is formed on the exposed n-type GaN layer 4 (in the figure, the p-electrode 8 and the n-electrode 9 are both illustrated as rectangular, and may be different shapes to distinguish electrode polarities). As described in the background art, the micro LED chips in the prior art are manufactured separately, and in the process of manufacturing the display device, a huge amount of micro LED chips need to be transferred to the backplane, at this time, the p-electrode 8 and the n-electrode 9 of each micro LED chip need to be bonded with corresponding bonding electrodes (corresponding to both position and polarity) on the backplane, the p-electrode 8 and the n-electrode 9 of each micro LED chip need to be aligned with the corresponding bonding electrodes, and the p-electrode 8 and the n-electrode 9 of each micro LED chip have no left-right deviation and no rotation deviation, which greatly increases the difficulty of huge amount transfer. For example, referring to fig. 3, in the process of mass transfer (mass transfer can be performed by using the transfer head 100), since the spatial position of the micro LED chip 10 cannot be changed at will, when the electrodes are aligned, if the p-electrode 8 and the n-electrode 9 of a part of the micro LED chip 10 are deviated from each other, or even cannot be aligned with the bonding electrode 201 on the back plate 200, the display of a part of the area of the display panel is abnormal; meanwhile, the polarities of the electrodes of the micro LED chip 10 need to be considered, i.e., the p-electrode 8 and the n-electrode 9 are distinguished, so that the p-electrode 8 and the n-electrode 9 are electrically connected with the bonding electrode 201 of the corresponding polarity on the back plate 200. For another example, referring to fig. 4, in the process of transferring a large amount, since the spatial position of the micro LED chip 10 cannot be changed at will, when the electrodes are aligned, if a rotational deviation occurs in the p-electrode 8 and the n-electrode 9 of a part of the micro LED chip 10, an electrical contact area between one of the electrodes (e.g., the n-electrode 9 in the figure) and the corresponding bonding electrode 201 is small (even unable to be electrically contacted), which causes poor electrical contact between the micro LED chip 10 and the backplate 200, thereby causing abnormal display. Therefore, in order to improve the display quality of the display panel, the conventional micro LED chip 10 greatly increases the difficulty of mass transfer.
For the above reasons, an embodiment of the present invention provides a micro LED chip, including: a substrate; the light-emitting layer group is positioned on the substrate and at least comprises a first type semiconductor layer, a light-emitting layer and a second type semiconductor layer which are arranged in a laminated mode; the first electrode and the second electrode are positioned on one side of the light-emitting layer group away from the substrate, the first electrode is electrically connected with the first type semiconductor layer, and the second electrode is electrically connected with the second type semiconductor layer; the first electrode is a ring electrode, the patterns of the outer edge and the inner edge of the first electrode are the same, and the second electrode is positioned in the middle of the area surrounded by the inner edge of the first electrode. According to the embodiment of the invention, the first electrode is set as the annular electrode, and the second electrode is set in the middle of the area surrounded by the inner edge of the first electrode, so that the polarity of the first electrode and the second electrode and the rotation deviation of the micro LED chip are not required to be considered or distinguished, at least one part of the first electrode and the second electrode can be ensured to be electrically connected with the bonding electrode at the corresponding position on the back plate, namely, the first electrode and the second electrode are always electrically connected with the bonding electrode at the corresponding position on the back plate no matter how the micro LED chip rotates, the phenomenon that the electric contact area of one electrode and the bonding electrode is too small or even no electric contact is avoided, the electric connection performance of the micro LED chip and the back plate is improved, and the problem that the space position of the micro LED chip cannot be randomly changed to cause the alignment deviation in the process of mass transfer is solved. Therefore, the embodiment of the invention reduces the difficulty of mass transfer of the micro LED chip.
It is understood that the multilayer film layer stacking arrangement is only used for limiting the relative position relationship of the film layers in the longitudinal direction, and is not used for limiting the contact arrangement of the film layers, that is, other film layers can exist between the film layers in the multilayer film layer stacking arrangement. For example, in this embodiment, the light emitting layer group includes at least a first type semiconductor layer, a light emitting layer, and a second type semiconductor layer, which are stacked, and another layer, such as an electron blocking layer, may be further disposed between the first type semiconductor layer and the light emitting layer or between the second type semiconductor layer and the light emitting layer. The specific film layer can be determined according to the actual situation, and the invention is not limited to this.
The first electrode is an n-electrode, 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 electrode is an n-electrode, and 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 invention does not limit the polarity of the first electrode and the second electrode, as long as the polarity is matched with that of the bonding electrode on the back plate, and the first electrode is arranged around the second electrode.
Specifically, in one 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 of a micro LED chip according to an embodiment of the present invention; FIG. 6 is a schematic cross-sectional view taken along the line B1-B2 in FIG. 5. As shown in fig. 5 and 6, the micro LED chip includes:
a substrate 101;
a first type semiconductor layer 102, a light emitting layer 103 and a second type semiconductor layer 104 which are arranged in a stacked manner, wherein the first type semiconductor layer 102 is positioned on one side of the light emitting layer 103 close to the substrate 101;
a first electrode 105 and a second electrode 106 on a side of the light emitting layer group away from the substrate 101; an annular groove (corresponding to a region outside a circular dotted line in fig. 5) is formed in a peripheral region of the micro LED chip, the annular groove penetrates through the second type semiconductor layer 104 and the light emitting layer 103 and exposes the first type semiconductor layer 102, the first electrode 105 is formed on the exposed first type semiconductor layer 102, the first electrode 105 is an annular electrode, and the first electrode 105 is electrically connected with the first type semiconductor layer 102; a 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 should be understood that fig. 5 and fig. 6 only schematically illustrate a structure of a practicable micro LED chip, a top profile of a single micro LED chip may also be triangular, rectangular, hexagonal, or the like, and the top profile of the single micro LED chip may be divided by a cutting street with a corresponding shape according to actual needs; the patterns of the outer edge and the inner edge of the first electrode and the patterns of the second electrode can also be arranged into regular or irregular patterns according to actual conditions; in addition, fig. 6 only shows a main film structure of the micro LED chip, and the micro LED chip provided in the embodiment of the present invention may further include other functional films, which is not limited in the present invention.
Accordingly, the preparation method of the micro LED chip may include: epitaxially growing a first-type semiconductor layer 102, a light-emitting layer 103 and a second-type semiconductor layer 104 on a wafer in sequence; forming a cutting channel pattern by adopting a photoetching process to divide areas of a plurality of micro LED chips, and etching the cutting channel pattern to penetrate through a light-emitting layer group by adopting a plasma etching process to divide the plurality of micro LED chips; forming an annular groove pattern in the peripheral area of each micro LED chip by adopting a photoetching process, etching the exposed light-emitting layer group by adopting a plasma etching process until the second-type semiconductor layer 104 and the light-emitting layer 103 are etched through, exposing the first-type semiconductor layer 102 and forming an annular groove; forming a first electrode pattern in the annular groove by using a photolithography process, forming a second electrode pattern in the middle of the second-type semiconductor layer 104 which is not etched (the photoresist at the first electrode pattern and the second electrode pattern is removed), evaporating a metal material on the whole surface by using a metal evaporation process, and stripping the residual photoresist by using a stripping process to enable the metal on the photoresist to fall off, thereby forming an annular first electrode 105 positioned in the annular groove and a second electrode 106 positioned in the middle of the second-type semiconductor layer 104.
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 of another micro LED chip according to an embodiment of the present invention; FIG. 8 is a schematic sectional view taken along the line C1-C2 in FIG. 7. As shown in fig. 7 and 8, the micro LED chip includes:
a substrate 101;
a first type semiconductor layer 102, a light emitting layer 103 and a second type semiconductor layer 104 which are arranged in a stacked manner, wherein the second type semiconductor layer 104 is positioned on one side of the light emitting layer 103 close to the substrate 101;
a first electrode 105 and a second electrode 106 on a side of the light emitting layer group away from the substrate 101; a groove (corresponding to an area within a circular dotted line in fig. 7) is formed in the middle region of the micro LED chip, the groove penetrates through the first type semiconductor layer 102 and the light emitting layer 103 and exposes the second type semiconductor layer 104, the second electrode 106 is formed on the exposed second type semiconductor layer 104, and the second electrode 106 is electrically connected with the second type semiconductor layer 104; the first electrode 105 is formed on the first type semiconductor layer 102 surrounding the groove and the first electrode 105 is a ring electrode, the first electrode 105 is electrically connected to the first type semiconductor layer 102.
Alternatively, in each of 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 a p-type GaN, and the light emitting layer may be a single quantum well layer or a multiple quantum well layer. In addition, the first electrode and the second electrode can be metal reflecting electrodes, and light emitted towards the first electrode or the second electrode can be returned to the light emitting surface by arranging the first electrode and the second electrode as the metal reflecting electrodes, so that the light emitting efficiency of the micro LED chip is improved, and the power consumption of the micro LED chip can be reduced. The metal reflective electrode may be a metal stack having a reflective effect, such as Cr/Al/Ti/Pt/Au.
In the technical scheme of the embodiment, the first electrode is set as the annular electrode, the second electrode is set in the middle of the area surrounded by the inner edge of the first electrode, and when the micro LED chip is transferred to the back plate with the bonding electrodes matched with the first electrode and the second electrode of the micro LED chip, on one hand, the first electrode and the second electrode are only required to be electrically connected with the bonding electrodes at corresponding positions (inside to outside and inside to outside) on the back plate, and the polarities of the first electrode and the second electrode do not need to be considered or distinguished; on the other hand, when the micro LED chip has rotation deviation, at least one part of the first electrode and the second electrode can be respectively and electrically connected with the bonding electrode at the corresponding position on the back plate, thereby avoiding overlarge alignment deviation of one electrode caused by the rotation deviation of the micro LED chip in the process of transferring a huge amount, preventing the electrical contact area between the electrode and the bonding electrode from being too small or even having no electrical contact, further avoiding the poor electrical contact between the micro LED chip and the back plate, and simultaneously, due to the structure of the first electrode and the second electrode, the rotation deviation of the micro LED chip does not influence the electric connection between the first electrode and the second electrode and the bonding electrode at the corresponding position on the back plate, therefore, rotational misalignment of the micro LED chips can occur during bulk transfer without correction of the misalignment, and the problem of contraposition deviation caused by the fact that the space position of the micro LED chip cannot be randomly changed in the process of mass transfer is solved. In addition, because the patterns of the outer edge and the inner edge of the first electrode are the same, the circumferential distribution uniformity of each first electrode can be improved, so that the uniformity of the electric contact area of each first electrode and the bonding electrode at the corresponding position on the back plate can be improved, and the display effect is improved. Therefore, the technical scheme 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 the micro LED chip is transferred in a huge amount, the problem of contraposition deviation caused by the fact that the space position of the micro LED chip cannot be changed randomly is solved, and the difficulty in transferring the huge amount of the micro LED chip is further reduced.
Optionally, the outer edge and the inner edge of the first electrode are in a figure with a geometric center, and the geometric centers coincide; preferably, the outer and inner edges of the first electrode are circular or regular polygonal.
When the outer edge and the inner edge 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 back plate always have the same electric contact area, and under the condition that the left-right deviation of the micro LED chip is not considered, the first electrode and the bonding electrode at the corresponding position on the back plate are always in full alignment contact. Referring to fig. 9, when the outer and inner sides of the first electrode 105 are regular polygons (illustrated as squares) and there is a rotational deviation of the micro LED chip, without considering the left-right deviation of the micro LED chip, each side of the first electrode 105 corresponding to the regular polygon has at least two electrical contact surfaces Z with the bonding electrode 201 at the corresponding position on the back plate; at a rotation angle of the micro LED chip of
And when the number of the first electrodes is the integral multiple of the number of the second electrodes, the first electrodes are always in full alignment contact with the bonding electrodes at the corresponding positions on the back plate, wherein n is the number of the sides of the regular polygon. For example, when the regular polygon is a square (regular quadrangle), and the micro LED chip rotates 90 °, 180 °, and 270 °, the first electrode and the bonding electrode at the corresponding position on the back plate are always in full alignment contact with each other。
In the technical scheme, the outer edge and the inner edge of the first electrode are coincident with the figure with the geometric center and the geometric center, so that the overall structure of the first electrode has higher symmetry, when the micro LED chip has rotation deviation, the bonding electrodes at the corresponding positions on the first electrode and the back plate always have larger electric contact area, the electric connection performance of the micro LED chip and the back plate is improved, and the display reliability is further improved.
As mentioned above, optionally, the pattern of 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 the micro LED chip has the rotation deviation, the micro LED chip basically rotates by taking the geometric center of the outer edge or the inner edge of the first electrode as a rotation center, and if the geometric center of the second electrode does not coincide with the geometric center of the outer edge or the inner edge of the first electrode, along with the difference of the rotation deviation or the rotation angle, the electric contact area of the bonding electrode at the corresponding position on the second electrode and the back plate can have a smaller condition, so that the risk of poor contact between the micro LED chip and the back plate exists. Based on this, this technical scheme is through setting up the geometric centre coincidence of the geometric centre of second electrode and the outside or the interior limit of first electrode, and when miniature LED chip had the rotational deviation, first electrode and second electrode all had bigger electric contact area with the nation fixed electrode of corresponding position on the backplate, have further improved the electric connection performance of miniature LED chip and backplate, effectively prevent miniature LED chip and backplate electric contact badly.
Further, the second electrode is formed in the same pattern as the outer edge or the inner edge of the first electrode.
For example, the pattern formed by the second electrode and the pattern of the outer edge or the inner edge of the first electrode are the same regular polygon, and the rotation angle of the micro LED chip is
At integral multiple of the first electrode, the first electrode and the second electrode are in full alignment contact with the bonding electrode at the corresponding position on the back plateWhere n is the number of sides of the regular polygon. In addition, when one of the electrodes of the micro LED chip is aligned, 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 edge or the inner edge of the first electrode, the pattern formed by the second electrode is set to be the same as the pattern of the outer edge or the inner edge of the first electrode, and when one of the electrodes is completely aligned with the bonding electrode at the corresponding position on the back plate, the other electrode can be ensured to be completely aligned with the bonding electrode at the corresponding position on the back plate, thereby reducing the alignment difficulty and improving the mass transfer efficiency.
Optionally, the second electrode is circular and/or the outer or inner edge of the first electrode is circular.
Based on the technical scheme, on the basis that the geometric center of the second electrode is superposed with the geometric center of the outer edge or the inner edge of the first electrode, the second electrode is set to be circular, and/or the outer edge or the inner edge of the first electrode is circular, namely at least one of the outer edge or the inner edge of the second electrode and the inner edge of the first electrode is set to be circular, so that no matter how the micro LED chip rotates, the complete alignment of at least one of the first electrode and the second electrode and the bonding electrode at the corresponding position on the back plate can be always ensured, the electric contact area of the first electrode and/or the second electrode and the bonding electrode at the corresponding position on the back plate is increased, the electric connection performance of the micro LED chip and the back plate is further improved, and the micro LED chip and the back plate are effectively prevented from being in poor electric contact.
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, where the conductive filling layer 107 is formed between the n-electrode (the first electrode 105 in the figure) and the n-type semiconductor layer (the first type semiconductor layer 102 in the figure), and the n-electrode is electrically connected to the n-type semiconductor layer through the conductive filling layer 107.
Illustratively, the conductive filling layer 107 may be prepared by the same process as the above-mentioned first electrode and 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, and the material of the conductive filling layer 107 may be Al \ Au.
This technical scheme is through forming the electrically conductive filling layer between n electrode and n type semiconductor layer, and the thickness of electrically conductive filling layer is adjusted to the accessible, makes the thickness of the nation decides the electrode that corresponds the position on the highly adaptation backplate of first electrode and second electrode to make first electrode and second electrode and the nation who corresponds decide the electrode simultaneous contact, avoid miniature LED chip nation to take place the slope after on the backplate, and then avoid influencing 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 a via hole.
Illustratively, an ITO layer may be formed by evaporation or sputtering, and the ITO layer on the second type semiconductor layer 104 is remained by a photolithography process and wet etching, so as to form the transparent metal oxide layer 108 as an ohmic contact of the second electrode 106; TiO evaporation by adopting PVD (physical vapor deposition) mode2And SiO2Or growing SiO by PECVD2Or a SiN film layer, forming a protective layer 109, then etching a portion of the protective layer 109 by a photolithography process and an etching (dry or wet) technique to expose the conductive filling layer 107 and the transparent metal oxide layer 108, and subsequently forming a first electrode 105 and a second electrode 106 in electrical contact with the conductive filling layer 107 and the transparent metal oxide layer 108, respectively.
In addition, an embodiment of the present invention further provides a display panel, as shown in fig. 11, the display panel includes a back plate 300 and a plurality of micro LED chips 20 provided in any of the above embodiments; the back plate 300 is provided with a bonding electrode 301 matched with (identical in shape, size and position to) the first electrode 105 and the second electrode 106 of the micro LED chip 20, and the micro LED chip 20 is bonded to the bonding electrode 301 through the first electrode 105 and the second electrode 106 and then is inversely mounted on the back plate 300. The display panel can be applied to display equipment such as mobile phones, computers, televisions and intelligent wearable display devices, and the embodiment of the invention is not particularly limited to this.
The display panel provided by the embodiment of the invention comprises the micro LED chip provided by the embodiment of the invention, has the same functions and effects, and is not described again here.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The previous description of the disclosed embodiments is provided to enable 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 applied to 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 (8)
1. The display panel is characterized by comprising a back plate and a plurality of micro LED chips arranged on the back plate;
the micro LED chip includes:
a substrate;
the light-emitting layer group is positioned on the substrate and at least comprises a first type semiconductor layer, a light-emitting layer and a second type semiconductor layer which are arranged in a stacked mode;
the first electrode and the second electrode are positioned on one side, far away from the substrate, of the light-emitting layer group, the first electrode is electrically connected with the first type semiconductor layer, and the second electrode is electrically connected with the second type semiconductor layer; the first electrode is a ring electrode, the patterns of the outer edge and the inner edge of the first electrode are the same, and the second electrode is positioned in the middle of the area surrounded by the inner edge of the first electrode;
the outer edge and the inner edge of the first electrode are in a figure with a geometric center, and the geometric centers are overlapped;
the outer edge and the inner edge of the first electrode are circular;
the back plate is provided with a bonding electrode matched with a first electrode and a second electrode of the micro LED chip, and the micro LED chip is inversely installed on the back plate after being bonded by the first electrode and the second electrode and the bonding electrode.
2. The display panel of claim 1, wherein the pattern of second electrodes has a geometric center, and wherein the geometric center of the second electrodes coincides with the geometric center of the outer edge or the inner edge of the first electrodes.
3. The display panel according to claim 2, wherein the second electrode is formed in the same pattern as an outer edge or an inner edge of the first electrode.
4. The display panel according to claim 2, wherein the second electrode is circular.
5. The display panel 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, the second type semiconductor layer is a p-type semiconductor layer, and the first type semiconductor layer is located on a side of the light-emitting layer adjacent to the substrate;
an annular groove is formed in the peripheral area of the micro LED chip, the annular groove penetrates through the second type semiconductor layer and the light emitting layer and exposes the first type semiconductor layer, and the first electrode is formed on the exposed first type semiconductor layer.
6. The display panel according to claim 1, wherein 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, the second type semiconductor layer is an n-type semiconductor layer, and the second type semiconductor layer is located on a side of the light-emitting layer adjacent to the substrate;
the middle area of the micro LED chip is provided with a groove, the groove penetrates through the first type semiconductor layer and the luminous layer and exposes the second type semiconductor layer, and the second electrode is formed on the exposed second type semiconductor layer.
7. The display panel of claim 5 or 6, wherein the micro LED chip further comprises a conductive filling layer formed between the n-electrode and the n-type semiconductor layer.
8. The display panel according to claim 1, wherein the first electrode and the second electrode are metal reflective electrodes.
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| CN110957402A (en) * | 2019-11-26 | 2020-04-03 | 晶能光电（江西）有限公司 | MicroLED chip and preparation method thereof |
| WO2021109093A1 (en) * | 2019-12-05 | 2021-06-10 | 重庆康佳光电技术研究院有限公司 | Micro device and display device |
| CN113544865B (en) * | 2019-12-31 | 2024-03-08 | 重庆康佳光电科技有限公司 | Light emitting diode chip, display panel and electronic equipment |
| US11843073B2 (en) | 2020-02-24 | 2023-12-12 | PlayNitride Display Co., Ltd. | Micro LED display device and manufacturing method thereof |
| CN111430523B (en) * | 2020-02-24 | 2021-06-01 | 錼创显示科技股份有限公司 | Micro light-emitting diode structure, manufacturing method thereof and micro light-emitting diode device |
| CN111564542B (en) * | 2020-05-21 | 2021-06-15 | 錼创显示科技股份有限公司 | Micro light-emitting diode |
| CN112635512B (en) * | 2020-12-18 | 2023-08-29 | 河源市众拓光电科技有限公司 | Visible light communication LED device |
| CN113611787B (en) * | 2021-08-02 | 2023-03-14 | 东莞市中麒光电技术有限公司 | Chip transfer structure and Micro LED display module repair method |
| CN113937095B (en) * | 2021-09-30 | 2022-11-04 | 厦门天马微电子有限公司 | Display panel and display device |
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