CN113497011A - Pixel unit structure of LED display and mass transfer method - Google Patents

Pixel unit structure of LED display and mass transfer method Download PDF

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Publication number
CN113497011A
CN113497011A CN202010192493.9A CN202010192493A CN113497011A CN 113497011 A CN113497011 A CN 113497011A CN 202010192493 A CN202010192493 A CN 202010192493A CN 113497011 A CN113497011 A CN 113497011A
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led chip
height
adhesive layer
boss
electrode group
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洪温振
徐瑞林
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Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
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Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
    • H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
    • H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
    • H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
    • H01L25/0753—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
    • H01L2221/67—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere
    • H01L2221/683—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L2221/68304—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L2221/68368—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support used in a transfer process involving at least two transfer steps, i.e. including an intermediate handle substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
    • H01L2221/67—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere
    • H01L2221/683—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L2221/68304—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L2221/68381—Details of chemical or physical process used for separating the auxiliary support from a device or wafer
    • H01L2221/68386—Separation by peeling

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
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  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
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  • Manufacturing & Machinery (AREA)
  • Led Device Packages (AREA)
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Abstract

The invention relates to the field of display manufacturing, in particular to an LED display pixel unit structure, which comprises a display back plate, wherein an array on the display back plate is divided into a plurality of pixel areas; each pixel region comprises a first LED chip, a third LED chip, a first boss with the height h1 and a second boss with the height h2, wherein the first boss, the third LED chip and the first boss are arranged on the display back plate; the height h1 of the first boss is less than or equal to the height h2 of the second boss; the first LED chip is arranged on the display back plate in the pixel area and comprises a first electrode group, the height of the first electrode group is hr, and hr is more than or equal to h 2; the second LED chip is arranged on the first boss, and the third LED chip is arranged on the second boss. The invention also relates to a bulk transfer method, which can reduce the manufacturing requirement of the transfer head by temporarily increasing the size of each LED chip through the photoresist.

Description

Pixel unit structure of LED display and mass transfer method
Technical Field
The invention relates to the technical field of LED display device manufacturing, in particular to an LED display pixel unit structure and a huge LED chip transfer method.
Background
With the increasing demand of the market on the display screen, Micro-LEDs are rapidly introduced into the market when the Micro-distance display screen is more Micro, and the LED usage of each Micro-distance panel is increased in geometric progression.
The 'mass transfer' difficulty is high, the circuit becomes a road barricade for realizing industrialization of the Micro-LED at present, and the matter is not secret in the industry. Therefore, various enterprises focusing on a huge amount of transfer technologies are also various exquisitely recruited, and hope to overcome difficulties and improve transfer efficiency by means of opportunities so as to further promote Micro-LEDs to realize industrialization. In the traditional LED packaging link, the LED is mainly transferred in a vacuum suction mode. However, since the vacuum tube can only be about 80 μm under physical limit, and the size of Micro-LED is substantially smaller than 50 μm, the vacuum absorption mode is no longer applicable in the Micro-LED era. However, along with the logic of "drawing", at least three precise grabbing (Fine Pick/Place) techniques are developed in the industry: "electrostatic force", "Vanderwatt force" and "magnetic force". In addition, the technology of opening brain cavities has been developed as a black technology in three directions of Selective Release (Selective Release), Self-Assembly (Self-Assembly) and transfer Printing (Roll Printing). However, the difficulty of mass transfer is how to increase the transfer yield to 99.9999% (commonly called "six nine"), and the precision of each chip must be controlled within plus or minus 0.5 μm, while the transfer efficiency is also considered.
Disclosure of Invention
Based on the above problems, the invention designs an LED display pixel unit structure and a bulk transfer method, which can well realize the bulk transfer of micro LED chips, and the LED display pixel unit structure is as follows:
a pixel unit structure of an LED display comprises an LED display pixel unit structure and is characterized by comprising a display back plate, wherein an array on the display back plate is divided into a plurality of pixel areas;
each pixel region comprises a first LED chip, a second LED chip, a third LED chip, a first boss with the height of h1 and a second boss with the height of h2, wherein the first boss, the second boss and the third boss are arranged on the display back plate; height h1 of the first boss
Less than or equal to the height h2 of the second boss;
the first LED chip is arranged on the display back plate in the pixel area and comprises a first electrode group, the height of the first electrode group is hr, and hr is more than or equal to h 2;
the second LED chip is arranged on the first boss,
further, the height of the first LED chip is hRThe second LED chip comprises a second electrode group, and the height of the first electrode group is hg，hg+h1＞hR。
Further, the height of the second LED chip is hGThe third LED chip comprises a third electrode group, and the height of the third electrode group is hb，hb+h2≥hG+h1。
Further, electrode groups which are bonded to the LED chips and correspond to the first electrode group, the second electrode group and the third electrode group are respectively formed on the display back plate, the first boss and the second boss, so that the first LED chip, the second LED chip and the third LED chip are electrically connected to the display back plate.
The invention also relates to a mass transfer method, which comprises the following steps:
s10, providing a growth substrate, wherein a first LED chip grows on the growth substrate, and a first electrode group formed on the first LED chip is deviated from the growth substrate;
s11 providing a first temporary substrate, wherein a first adhesive layer is formed on a surface of the first temporary substrate, the first adhesive layer is close to the first LED chip and adheres the first electrode set, and then the growth substrate is peeled off from the first LED chip;
s12 providing a second temporary substrate, the second temporary substrate having a second adhesive layer formed on a surface thereof, the second adhesive layer being adjacent to and adhering the first LED chip, and then selectively separating the first LED chip to be transferred from the first adhesive layer by using a laser;
s13 in the second adhesionCoating a photoresist material on the agent layer to form a first photoresist layer, exposing the first electrode from the first photoresist layer, wherein the thickness of the first photoresist layer is H1, and the height of the first LED chip is HRHeight h of the first electrode groupr，H1≥hR-hr；
S14 transferring the first LED chip to the display backplane, bonding the first electrode to an electrode on the display backplane, and separating the first LED chip from the second adhesive layer with a laser;
s15 the first photoresist layer is removed by dissolving with a developing solution.
Furthermore, a first boss and a second boss are formed on the display back plate, and the height h1 of the first boss is less than or equal to the height h2, h of the second bossRH1 ≧ H2, whereby the height H of the first electrode grouprGreater than or equal to the height h2 of the second boss.
Further, the step S15, after the step of dissolving and removing the first photoresist layer with the developer solution,
s16 providing a second growth substrate on which a second LED chip is grown and formed
A second electrode group on the LED chip is deviated from the second growth substrate;
s17 providing a third temporary substrate, wherein a third adhesive layer is formed on a surface of the third temporary substrate, the third adhesive layer is close to the second LED chip and adheres to the second electrode group, and then the second growth substrate is peeled off from the second LED chip;
s18 providing a fourth temporary substrate, the surface of which is formed with a fourth adhesive layer, the fourth adhesive layer is close to and adheres to the second LED chip, and then the second LED chip to be transferred is selectively separated from the third adhesive layer by laser;
s19 coating a photoresist material on the fourth adhesive layer to form a second photoresist layer, the second electrode set exposed from the second photoresist layer, the second photoresist layerThe layer thickness is H2, and the height of the second LED chip is HGHeight h of said second electrode setg，H2≥hG-hg；
S20 transferring the second LED chip to the display backplane, bonding the second electrode set to the electrode set on the display backplane, and separating the second LED chip from the fourth adhesive layer with a laser;
s21, dissolving and removing the second photoresist layer by using a developing solution;
s22, providing a third growth substrate on which a third LED chip is grown and formed
A third electrode group on the LED chip is away from the third growth substrate;
s23 providing a fifth temporary substrate, wherein a fifth adhesive layer is formed on a surface of the fifth temporary substrate, the fifth adhesive layer is close to the third LED chip and adheres the third electrode group, and then the third growth substrate is peeled off from the third LED chip;
s24 providing a sixth temporary substrate, the sixth temporary substrate having a sixth adhesive layer formed on a surface thereof, the sixth adhesive layer being adjacent to and adhering the third LED chip, and then selectively separating the third LED chip to be transferred from the fifth adhesive layer by using a laser;
s25, coating a photoresist material on the sixth adhesive layer to form a third photoresist layer, exposing the third electrode from the third photoresist layer, wherein the thickness of the third photoresist layer is H3, and the height of the third LED chip is HBHeight h of the third electrode groupb，H3≥hB-hb；
S26 transferring the third LED chip to the display backplane, bonding the third electrode set to the electrode set on the display backplane, and separating the third LED chip from the sixth adhesive layer with a laser;
s27 dissolving and removing the third photoresist layer with a developer.
Further, the second LED chip includes a second electrode setThe height of the second LED chip is hGThe height of the first electrode group is hg，hg+h1＞hR。
Further, the third LED chip includes a third electrode set, and the height of the third electrode set is hb，hb+h2≥hG+h1。
Further, in step S13, after the first photoresist layer is formed, the first photoresist layer is cut into a plurality of LED chip units, each LED chip unit includes 1 first LED chip, and a lateral dimension of each LED chip unit is equal to a lateral dimension of one pixel on the display backplane.
The invention has the beneficial effects that:
the pixel unit structure of the LED display is provided with the boss for bearing the micro LED chips, so that the micro LED chips with different heights can be transferred by times by using the same method.
The size of each MICRO LED is temporarily increased through the photoresist, so that the transfer head can transfer each MICRO-LED conveniently, and the photoresist is dissolved by using the developing solution after the transfer head is transferred to the backboard, so that the manufacturing requirement on the transfer equipment can be reduced.
Drawings
FIG. 1 is a pixel unit structure of an LED display;
FIG. 2 is a schematic diagram of the bulk transfer method steps of the present invention;
FIG. 3 schematic view of a first LED chip on a growth substrate
FIG. 4 is a schematic view of a first LED chip transferred onto a first temporary substrate;
fig. 5 is a schematic view of a second temporary substrate picking up a first LED chip to be transferred;
FIG. 6 is a schematic diagram showing an array of LED chips on a backplane;
FIG. 7 is a schematic view of forming a first photoresist layer;
FIG. 8 is a schematic view after cutting the first photoresist layer;
FIG. 9 is a schematic view of transferring a first LED chip onto a display backplane;
FIG. 10 is a schematic view showing the first photoresist layer removed;
FIG. 11 is a schematic view of a second LED chip on a second growth substrate;
fig. 12 is a schematic view of a second LED chip transferred onto a third temporary substrate;
fig. 13 is a schematic view of a second LED chip to be transferred being transferred onto a fourth temporary substrate;
FIG. 14 is a schematic view after a second photoresist layer is formed and cut;
FIG. 15 is a schematic view of the fourth temporary substrate transferring the second LED chip onto the display backplane;
FIG. 16 is a schematic view of a second LED chip bonded to a display backplane;
fig. 17 is a schematic view of a third LED chip on a third growth substrate;
fig. 18 is a schematic view of a third LED chip transferred onto a fifth temporary substrate;
fig. 19 is a schematic view of a third LED chip to be transferred being transferred onto a sixth temporary substrate;
FIG. 20 is a schematic view of a third photoresist layer being formed and cut;
FIG. 21 is a schematic view of the sixth temporary substrate transferring the third LED chip onto the display backplane
FIG. 22 is a schematic view showing the third photoresist layer removed.
The reference numbers in the figures illustrate:
the display back plate 100, the first boss 110, the second boss 120, the first LED chip 210, the second LED chip 220, the third LED chip 230, the first electrode group 211, the second electrode 221, the third electrode 231, the first growth substrate 310, the first temporary substrate 320, the first adhesive layer 321, the second temporary substrate 330, the second adhesive layer 331, the first photoresist layer 340, the second growth substrate 410, the third temporary substrate 420, the third adhesive layer 421, the fourth temporary substrate 430, the fourth adhesive layer 431, the second photoresist layer 440, the third growth substrate 510, the fifth temporary substrate 520, the fifth adhesive layer 521, the sixth temporary substrate 530, the sixth adhesive layer 531, and the third photoresist layer 540.
Detailed Description
The technical solutions in the embodiments of the present application will be described below in a clear and complete manner with reference to the drawings in the embodiments of the present application, and the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments.
The terms "first", "second" and "third" in this application are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicit to the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of the feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
Example 1
Fig. 1 shows a pixel unit structure of an LED display according to the present invention.
The display back plate comprises a display back plate 100, wherein a first boss 110 and a second boss 120 are formed on the display back plate 100, a first LED chip 210 is arranged on the display back plate 100, a second LED chip 220 is arranged on the first boss 110, a third LED chip 230 is arranged on the second boss 120, the number of the second LED chips 220 is the same as that of the first boss 110, and the number of the third LED chips 230 is the same as that of the second boss 120.
The height of the first boss 110 is h1, the height of the second boss 120 is h2, h2 is not less than h1, the first LED chip 210 comprises a first electrode group 211, and the height of the first LED chip 210 is hRThe height of the first electrode group 211 is hrThen h isr≥h2。
The second LED chip 220 includes a second electrode 221, and the height of the second LED chip 220 is hGThe height of the first electrode 221 is hgIf hg + h1 > hR。
The third LED chip 230 includes a third electrode 231, and the height of the third electrode 231 is hbThen h isb+h2≥hG+h1。
Electrodes (not shown) correspondingly connected to the first electrode group 211, the second electrode 221 and the third electrode 231 are respectively formed on the display back plate 100, the first boss 110 and the second boss 120, so that the first LED chip 210, the second LED chip 220 and the third LED chip 230 are electrically connected to the display back plate 100.
The bosses with different heights are arranged to place the micro LED chips with different heights, so that the first LED chip 210, the second LED chip 220 and the third LED chip 230 can be respectively transferred by the same method when different chips are transferred, and when the chips are transferred to the display back plate 100, the micro LEDs cannot collide with other structures in the transferring process.
In the present embodiment, the first LED chip 210 is a red chip (R), the second LED chip 220 is a green chip (G), and the third LED chip 230 is a blue chip (B), it is understood that the types of the chips can be replaced with each other and are set according to the height of the chip. Meanwhile, the heights of the first boss 110 and the second boss 120 are specifically designed according to the height of the micro LED chip, and the LED chip with high manufacturing difficulty does not need to be changed, and only the height of the boss on the display back plate 100 needs to be changed, so that the manufacturing is simpler.
Example 2
FIG. 2 shows the steps of a mass transfer method according to the present invention, which includes the following steps.
S10 provides a first growth substrate 310, the first LED chip 210 is grown on the growth substrate 310, and the first electrode group 211 formed on the first LED chip 210 faces away from the first growth substrate 310.
Referring to fig. 3, the first LED chip 210 is formed on the growth substrate 310, the first LED chip 210 includes a first electrode group 211, and the first electrode group 211 is formed on a side away from the first growth substrate 310.
S11 provides a first temporary substrate 320, the first temporary substrate 320 has a first adhesive layer 321 formed on the surface thereof, the first adhesive layer 321 is adjacent to the first LED chip 210 and adheres the first electrode group 211, and then the first growth substrate 310 is peeled off from the first LED chip 210.
Referring to fig. 4, the first temporary substrate 320 is disposed over the first LED chip 210, and is in contact with the first electrode group 211, the first adhesive layer 321 is bonded to the first electrode group 211, and then the growth substrate 310 is separated from the first LED chip 210 by laser irradiation, so that the first LED chip 210 is transferred onto the first temporary substrate 320. The material of the first adhesive layer 321 is preferably a polyimide photosensitive adhesive, and may be other photosensitive adhesive materials having excellent properties.
S12 provides a second temporary substrate 330, the second temporary substrate 330 has a second adhesive layer 331 formed on the surface thereof, the second adhesive layer 331 is adjacent to and adheres to the first LED chip 210, and then the first LED chip to be transferred is selectively separated from the first adhesive layer 321 by a laser.
Referring to fig. 5, the first temporary substrate is transparent and can transmit light, the first adhesive layer 321 is formed by a photosensitive adhesive, and the first adhesive layer 321 is irradiated by light with a specific wavelength and loses its adhesiveness, so that the first LED chip 210 to be transferred is separated from the first temporary substrate 320, adhered to the second adhesive layer 331, and transferred through the second temporary substrate 330 to the first LED chip 210 to be transferred.
Referring to fig. 6, the lateral distance between the first LED chips 210 on the second temporary substrate is D, and the distance D between the same LED chips of two adjacent pixels on the display back plate 100 is n × D, where n is a natural number, so that the LED chips in a plurality of adjacent or non-adjacent pixel regions can be transferred, and the transfer accuracy is ensured.
S13 a photoresist material is coated on the second adhesive layer 331 to form a first photoresist layer 340, the first electrode group 211 is exposed from the first photoresist layer 340, and the first photoresist layer 340 is cut to separate the first LED chips 210 one by one.
Referring to fig. 7, the thickness of the first photoresist layer 340 is H1, and the height of the first LED chip 210 is HRThe height of the first electrode group 211 is hrThen H1 is greater than or equal to HR-hrThat is, the first photoresist layer 340 completely covers the epitaxial layer of the first LED chip 210, so that the first LED chip 210 can be firmly fixed by the photoresist layer 340.
Referring to fig. 8, the first photoresist layer 340 is cut into a plurality of LED chip units, each LED chip unit wraps one first LED chip 210, which is equivalent to enlarging the volume of the first LED chip 210. The cutting method can be laser cutting, or removing part of the photoresist material by exposure and development.
S14 transfers the first LED chip 210 to the display backplane 110, bonds the first electrode group 211 to electrodes (not shown) on the display backplane 100, and separates the first LED chip 210 from the second adhesive layer 331 with a laser.
Referring to fig. 9, the second adhesive layer 331 is made of a photosensitive material, loses its adhesiveness after being irradiated by laser, and is separated from the first LED chip 210 and the photoresist layer 340, and the separated structure is shown in fig. 8, where a lateral dimension L1 of each LED chip unit is the same as a lateral dimension L2 of a pixel on the display backplane 100.
The display back plate 100 is formed with a first boss 110 and a second boss 120, the height h1 of the first boss 110 is less than or equal to the height h2, h of the second boss 120RH1 ≧ H2, whereby the height H of the first electroderThe height h2 of the second protrusion is greater than or equal to, so that when the first LED chip 210 is transferred to the display back plate 100, the first electrode set 211 can smoothly contact the display back plate 100 without being lifted by the second protrusion 120.
S15 the first photoresist layer 340 is removed by dissolving with a developer.
Referring to fig. 10, after removing the photoresist layer 340, the photoresist can be dissolved by a developing solution without peeling off and stress is not generated on the first LED chip 210.
S16 provides a second growth substrate 410, the second growth substrate 410 has a second LED chip 220 grown thereon, and the second LED chip 220 has a second electrode set 221 formed thereon and facing away from the second growth substrate 410.
Referring to fig. 11, the second LED chip 210 includes a second electrode group 221, the second electrode group 221 is composed of a plurality of electrodes, and the specific number of the electrodes is determined by the design of the LED chip, which is not limited herein.
S17 provides a third temporary substrate 420, a third adhesive layer 421 is formed on the surface of the third temporary substrate 420, the third adhesive layer 421 is close to the second LED chip 220 and adheres the second electrode group 221, and then the second growth substrate 410 is peeled off from the second LED chip 220.
Referring to fig. 12, the third temporary substrate 420 is transparent, and the third adhesive layer 421 is a photosensitive adhesive, which loses its adhesiveness under the irradiation of light with specific wavelength.
S18 provides a fourth temporary substrate 430, a fourth adhesive layer 431 is formed on the surface of the fourth temporary substrate 430, the fourth adhesive layer 431 is adjacent to and adheres to the second LED chip 220, and then the second LED chip 220 to be transferred is selectively separated 421 from the third adhesive layer by using a laser.
Referring to fig. 13, the fourth temporary substrate 430 is disposed close to the second LED chip 220, the fourth adhesive layer 431 is adhered to the epitaxial layer of the second LED chip 220, and then a patterned mask (not shown) is disposed under the third temporary substrate 420, so that only the region under the second LED chip 220 to be transferred can transmit light, and the third adhesive layer 421 loses adhesiveness after being irradiated by light and is separated from the second electrode group 221, so that the second LED chip 220 to be transferred is adhered to the fourth adhesive layer 431.
S19 a photoresist material is coated on the fourth adhesive layer 431 to form a second photoresist layer 440, the second electrode group 221 is exposed from the second photoresist layer 440, and the second photoresist layer 440 is cut to separate the second LED chips 220 one by one.
Referring to fig. 14, the thickness of the second photoresist layer 440 is H2, and the height of the second LED chip 220 is HGHeight h of the second electrode set 221gThe condition H2 is required to be more than or equal to HG-hgSo that the second LED chip 220 does not collide with the first LED chip 210 when transferred onto the display back panel 100. The first photoresist layer 340 is cut into a plurality of second LED chip units, each of which wraps one of the first LED chips 210, which is equivalent to enlarging the volume of the first LED chip 210. The cutting method can be laser cutting, or removing part of the photoresist material by exposure and development.
S20 transfers the second LED chip 220 to the display backplane 110, bonds the second electrode set 221 to an electrode set (not shown) on the display backplane, and separates the second LED chip 220 from the fourth adhesive layer 431 with a laser.
Referring to fig. 15, the fourth temporary substrate 430 is a transparent substrate, and the fourth adhesive layer 431 is a photosensitive adhesive, loses its adhesiveness after being irradiated by laser, and is separated from the second photoresist layer 440.
S21 is dissolved by the developer to remove the second photoresist layer 440.
Referring to fig. 16, the second photoresist layer 440 can be removed by a developer solution, so as to not generate stress on the second LED chip 220, and the second LED chip 220 can be removed well, so as to be accurately transferred to the display back panel 100.
Referring to fig. 17, S22 provides a third growth substrate 510, the third growth substrate 510 has a third LED chip 230 grown thereon, and the third electrode set 231 formed on the third LED chip 230 is away from the third growth substrate 230.
Referring to fig. 18, S23 provides a fifth temporary substrate 520, a fifth adhesive layer 521 is formed on the surface of the fifth temporary substrate 520, the fifth adhesive layer 521 is close to the third LED chip 230 and adheres to the third electrode group 231, and then the third growth substrate 510 and the third LED chip 230 are peeled off. The mode of stripping is laser irradiation.
Referring to fig. 19, S24 provides a sixth temporary substrate 530, a sixth adhesive layer 531 is formed on the surface of the sixth temporary substrate 530, the sixth adhesive layer 531 is close to and adheres to the third LED chip 230, and then the third LED chip 230 to be transferred is selectively separated from the fifth adhesive layer 521 by using a laser.
Referring to fig. 20, S25 coats a photoresist material on the sixth adhesive layer 531 to form a third photoresist layer 540, the third electrode group 231 is exposed from the third photoresist layer 540, and the third photoresist layer 540 is cut to separate the third LED chips 230 one by one.
The third photoresist layer 540 has a thickness of H3 and the third LED chip 230 has a height of HBHeight h of the third electrode group 231b，H3≥hB-hb. So that the third LED chip 231 is transferred to the second bump 120 on the display back plate 100 without colliding with the transferred second LED chip 220.
Referring to fig. 21, S26 transfers the third LED chip 230 to the display back plate 100, bonds the third electrode group 231 to the electrode group on the display back plate 100, and separates the third LED chip 230 from the sixth adhesive layer 531 with a laser.
Referring to fig. 22, S27 is performed by removing the third photoresist layer by dissolving with a developer.
The third photoresist layer 540 can be removed by a developing solution, does not generate stress on the third LED chip 230, and can be removed well, so that the third LED chip 230 can be accurately transferred to the display backplane 100.
In this embodiment, the third temporary substrate 420, the fourth temporary substrate 430, the fifth temporary substrate 520, and the sixth temporary substrate 530 are transparent substrates, allowing light to pass through, so as to successfully complete the process of separating the second LED chip 220 and the third LED chip 230 by using laser.
The first LED chip 210, the second LED chip 220 and the third LED chip 230 are transferred in the same manner, but the transfer process needs to avoid collision with each other because the chip height and the electrode height are different.
The types of the current LED chips are usually 3 according to their different wave bands, which are a red wave band LED chip, a green wave band LED chip, and a blue wave band LED chip. In this embodiment, the first LED chip 210 is a red-wavelength LED chip, the second LED chip 220 is a green-wavelength LED chip, and the third LED chip 230 is a blue-wavelength LED chip. In other embodiments, the LED chips may be combined with other different types of LED chips, and the embodiment is not limited to this example.
The three LED chips are RGB three-color LED chips according to practical application, the transferring sequence is that the LED chips on the display back plate 100 are transferred firstly, then the LED chips on the first boss 110 are transferred, and finally the LED chips on the second boss 120 are transferred, the types of the chips are not limited, but the transferring positions need to be carried out in sequence.
The size of each MICRO LED is temporarily increased through the photoresist, so that the transfer head can transfer each MICRO-LED conveniently, and the photoresist is dissolved by using the developing solution after the transfer head is transferred to the backboard, so that the manufacturing requirement on the transfer equipment can be reduced.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
The foregoing describes the general principles of the present disclosure in conjunction with specific embodiments, however, it is noted that the advantages, effects, etc. mentioned in the present disclosure are merely examples and are not limiting, and they should not be considered essential to the various embodiments of the present disclosure. Furthermore, the foregoing disclosure of specific details is for the purpose of illustration and description and is not intended to be limiting, since the disclosure is not intended to be limited to the specific details so described.

Claims (10)

1. The pixel unit structure of the LED display is characterized by comprising a display back plate, wherein an array on the display back plate is divided into a plurality of pixel areas;
each pixel region comprises a first LED chip, a second LED chip, a third LED chip, a first boss with the height of h1 and a second boss with the height of h2, wherein the first boss, the second boss and the third boss are arranged on the display back plate; the height h1 of the first boss is less than or equal to the height h2 of the second boss;
the first LED chip is arranged on the display back plate in the pixel area and comprises a first electrode group, the height of the first electrode group is hr, and hr is more than or equal to h 2;
the second LED chip is arranged on the first boss,
the third LED chip is arranged on the second boss.
2. The LED display pixel cell structure of claim 1, wherein the first LED chip has a height hRThe second LED chip comprises a second electrode group, and the height of the second electrode group is hg，hg+h1＞hR。
3. The LED display pixel cell structure of claim 2, wherein the second LED chip has a height hGSaid thirdThe LED chip comprises a third electrode group, and the height of the third electrode group is hb，hb+h2≥hG+h1。
4. The LED display pixel unit structure of claim 1, wherein the display back plate, the first boss and the second boss are respectively formed with electrode sets bonded to the LED chips corresponding to the first electrode set, the second electrode set and the third electrode set, such that the first LED chip, the second LED chip and the third LED chip are electrically connected to the display back plate.
5. A mass transfer method, comprising the steps of:
s10, providing a first growth substrate, wherein a first LED chip grows on the first growth substrate, and a first electrode group formed on the first LED chip is deviated from the growth substrate;
s11 providing a first temporary substrate, wherein a first adhesive layer is formed on a surface of the first temporary substrate, the first adhesive layer is close to the first LED chip and adheres the first electrode set, and then the growth substrate is peeled off from the first LED chip;
s12 providing a second temporary substrate, the second temporary substrate having a second adhesive layer formed on a surface thereof, the second adhesive layer being adjacent to and adhering the first LED chip, and then selectively separating the first LED chip to be transferred from the first adhesive layer by using a laser;
s13, coating a photoresist material on the second adhesive layer to form a first photoresist layer, exposing the first electrode from the first photoresist layer, wherein the thickness of the first photoresist layer is H1, and the height of the first LED chip is HRHeight h of the first electrode groupr，H1≥hR-hr；
S14 transferring the first LED chip to the display backplane, bonding the first electrode set to an electrode set on the display backplane, and separating the first LED chip from the second adhesive layer with a laser;
s15 the first photoresist layer is removed by dissolving with a developing solution.
6. The mass transfer method of claim 5, wherein the display backplane has a first protrusion and a second protrusion, the height h1 of the first protrusion is less than or equal to the height h2, h of the second protrusionRH1 ≧ H2, whereby the height H of the first electroderGreater than or equal to the height h2 of the second boss.
7. The mass transfer method according to claim 6, wherein the step S15, after the step of removing the first photoresist layer by dissolving with a developer, further comprises:
s16 providing a second growth substrate on which a second LED chip is grown, wherein a second electrode group formed on the second LED chip faces away from the second growth substrate;
s17 providing a third temporary substrate, wherein a third adhesive layer is formed on a surface of the third temporary substrate, the third adhesive layer is close to the second LED chip and adheres to the second electrode group, and then the second growth substrate is peeled off from the second LED chip;
s18 providing a fourth temporary substrate, the surface of which is formed with a fourth adhesive layer, the fourth adhesive layer is close to and adheres to the second LED chip, and then the second LED chip to be transferred is selectively separated from the third adhesive layer by laser;
s19, coating a photoresist material on the fourth adhesive layer to form a second photoresist layer, exposing the second electrode group from the second photoresist layer, wherein the second photoresist layer has a thickness of H2, and the second LED chip has a height of HGHeight h of said second electrode setg，H2≥hG-hg；
S20 transferring the second LED chip to the display backplane, bonding the second electrode set to the electrode set on the display backplane, and separating the second LED chip from the fourth adhesive layer with a laser;
s21, dissolving and removing the second photoresist layer by using a developing solution;
s22 providing a third growth substrate on which a third LED chip is grown, wherein a third electrode group formed on the third LED chip faces away from the third growth substrate;
s23 providing a fifth temporary substrate, wherein a fifth adhesive layer is formed on a surface of the fifth temporary substrate, the fifth adhesive layer is close to the third LED chip and adheres the third electrode group, and then the third growth substrate is peeled off from the third LED chip;
s24 providing a sixth temporary substrate, the sixth temporary substrate having a sixth adhesive layer formed on a surface thereof, the sixth adhesive layer being adjacent to and adhering the third LED chip, and then selectively separating the third LED chip to be transferred from the fifth adhesive layer by using a laser;
s25, coating a photoresist material on the sixth adhesive layer to form a third photoresist layer, wherein the third electrode group is exposed from the third photoresist layer, the thickness of the third photoresist layer is H3, and the height of the third LED chip is HBHeight h of the third electrode groupb，H3≥hB-hb；
S26 transferring the third LED chip to the display backplane, bonding the third electrode set to the electrode set on the display backplane, and separating the third LED chip from the sixth adhesive layer with a laser;
s27 dissolving and removing the third photoresist layer with a developer.
8. The mass transfer method of claim 7, wherein the second LED chip comprises a second set of electrodes, the second LED chip having a height hGThe height of the second electrode group is hg，hg+h1＞hR。
9. The mass transfer method of claim 8, wherein the mass transfer method is a mass transfer methodThe third LED chip includes a third electrode set, and the height of the third electrode set is hb，hb+h2≥hG+h1。
10. The mass transfer method according to claim 5, wherein in step S13, after the first photoresist layer is formed, the first photoresist layer is cut into a plurality of LED chip units, each LED chip unit comprises 1 first LED chip, and the lateral dimension of each LED chip unit is equal to the lateral dimension of one pixel on the display backplane.
CN202010192493.9A 2020-03-18 2020-03-18 Pixel unit structure of LED display and mass transfer method Pending CN113497011A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114400279A (en) * 2022-01-10 2022-04-26 东莞市中麒光电技术有限公司 LED chip mass transfer method
WO2023092594A1 (en) * 2021-11-29 2023-06-01 京东方科技集团股份有限公司 Light-emitting substrate and preparation method therefor, and display device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023092594A1 (en) * 2021-11-29 2023-06-01 京东方科技集团股份有限公司 Light-emitting substrate and preparation method therefor, and display device
CN114400279A (en) * 2022-01-10 2022-04-26 东莞市中麒光电技术有限公司 LED chip mass transfer method

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