CN112652697A

Movatterモバイル変換

Info

Publication number: CN112652697A
Application number: CN202110047623.4A
Authority: CN
Inventors: 张建华; 殷录桥; 嵇啸啸
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2021-01-14
Filing date: 2021-01-14
Publication date: 2021-04-13

Abstract

Translated fromChinese

本发明涉及一种柔性Micro LED基板结构及其制备方法，所述柔性Micro LED基板结构包括：衬底基板；导电金属层，固定在衬底基板上，并覆盖部分衬底基板，导电金属层的面积小于衬底基板的面积；平坦化层，覆盖剩余部分衬底基板，且厚度大于导电金属层的厚度，用于填平导电金属层；平坦化层对应导电金属层处开设有通孔；绝缘层，设置在平坦化层上，绝缘层对应通孔处开设有过孔；键合金属层，穿过过孔以及通孔与导电金属层连接，并覆盖部分所述绝缘层；发光二极管LED芯片，设置在键合金属层上，并与键合金属层连接，能够实现柔性显示，减小了芯片间距，从而达到了更好的显示效果。

The invention relates to a flexible Micro LED substrate structure and a preparation method thereof. The flexible Micro LED substrate structure comprises: a base substrate; a conductive metal layer, which is fixed on the base substrate and covers part of the base substrate, and the conductive metal layer The area is smaller than the area of the base substrate; the planarization layer covers the remaining part of the base substrate, and the thickness is greater than that of the conductive metal layer, which is used to fill the conductive metal layer; the planarization layer corresponds to the conductive metal layer with through holes; the insulating layer The insulating layer is provided with a via hole corresponding to the through hole; the bonding metal layer is connected to the conductive metal layer through the via hole and the through hole, and covers part of the insulating layer; the light-emitting diode LED chip , is arranged on the bonding metal layer and connected with the bonding metal layer, which can realize flexible display, reduce the chip spacing, and thus achieve a better display effect.

Description

Flexible Micro LED substrate structure and preparation method thereof

Technical Field

The invention relates to the technical field of display, in particular to a flexible Micro Light Emitting Diode (Micro LED) substrate structure and a preparation method thereof.

Background

In the field of display, flexible display has been the research direction of researchers, and Organic Light Emitting Diode (OLED) displays have made flexible display feasible due to their unique organic properties and simple display structure. With the continuous development of display technology, Micro LEDs (Micro light emitting diodes) are emerging as a future technology for flexible displays due to their advantages of high brightness, high contrast, long lifetime, high stability in extreme environments, and low power consumption for power saving. Although the flexible OLED device has many advantages, and the flexible OLED device has great progress in material lifetime, driving, brightness, colorization, flexibility, and the like, the industrialization process is low, mainly because the lifetime problem and the high efficiency problem are not completely solved. In the prior art, flexible display cannot be realized on both the PCB base and the glass base.

Disclosure of Invention

The invention aims to provide a flexible Micro LED substrate structure and a preparation method thereof, which can realize flexible display and reduce the chip spacing, thereby achieving better display effect.

In order to achieve the purpose, the invention provides the following scheme:

a flexible Micro LED substrate structure, comprising:

a substrate base plate;

the conductive metal layer is fixed on the substrate base plate and covers a part of the substrate base plate, and the area of the conductive metal layer is smaller than that of the substrate base plate;

the planarization layer covers the rest part of the substrate base plate, is thicker than the conductive metal layer and is used for filling and leveling the conductive metal layer; the planarization layer is provided with a through hole corresponding to the conductive metal layer;

the insulating layer is arranged on the planarization layer, and a through hole is formed in the insulating layer corresponding to the through hole;

the bonding metal layer penetrates through the through hole and the through hole to be connected with the conductive metal layer and covers part of the insulating layer;

and the light emitting diode LED chip is arranged on the bonding metal layer and is connected with the bonding metal layer.

Optionally, the flexible Micro LED substrate structure further includes:

and the passivation layer is arranged on the insulating layer and covers part of the bonding metal layer.

Optionally, the flexible Micro LED substrate structure further includes:

and the reflecting layer is arranged on the passivation layer and surrounds the periphery of the LED chip.

Optionally, the material of the conductive metal layer is copper.

Optionally, the material of the planarization layer is polyimide.

In order to achieve the above object, the present invention further provides the following solutions:

a preparation method of a flexible Micro LED substrate structure comprises the following steps:

forming a conductive metal layer on a substrate;

forming a planarization layer on the conductive metal layer by a spin coating process;

depositing an insulating layer on the planarization layer;

forming a through hole on the planarization layer corresponding to the conductive metal layer, and forming a via hole on the insulating layer corresponding to the through hole to expose the conductive metal layer;

forming a bonding metal layer on the insulating layer, and connecting the bonding metal layer with the conductive metal layer through the via hole and the through hole;

bonding a Light Emitting Diode (LED) chip with the bonding metal layer;

and stripping the base substrate by means of laser stripping.

Optionally, the method for preparing the flexible Micro LED substrate further includes:

depositing a passivation layer on the bonding metal layer through a composition process to expose the bonding metal layer to be bonded with the chip electrode, wherein the rest bonding metal layers are covered by the passivation layer;

the reflective layer is formed on the passivation layer by screen printing, thin film deposition, or inkjet printing.

Optionally, the forming a through hole on the planarization layer corresponding to the conductive metal layer, and forming a via hole on the insulating layer corresponding to the through hole to expose the conductive metal layer specifically include:

forming a photoresist pattern on the insulating layer and the planarization layer;

photoetching the insulating layer and the planarization layer, and removing part of the insulating layer through dry etching or wet etching;

removing part of the planarization layer through laser etching;

and forming a through hole with the area smaller than or equal to that of the conductive metal layer, and finally removing the photoresist.

Optionally, the forming a bonding metal layer on the insulating layer, and connecting the bonding metal layer with the conductive metal layer through the via hole and the through hole specifically includes:

forming a negative photoresist pattern on the insulating layer;

depositing a seed layer;

connecting the bonding metal layer with the conductive metal layer by electroplating or chemical coating process;

and stripping the metal on the photoresist by adopting a blue film, and removing the photoresist.

depositing a seed layer on the insulating layer;

forming a photoresist pattern on the bonding metal layer;

and photoetching the bonding metal layer, removing redundant metal in a dry etching or wet etching mode, and finally removing the photoresist.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects: according to the invention, the conductive metal layer is arranged on the substrate, the planarization layer is covered on the substrate, the insulation layer is arranged on the planarization layer, the bonding metal layer penetrates through the planarization layer and the insulation layer to be connected with the conductive metal layer, and the LED chip is connected with the bonding metal layer, so that flexible display can be realized, the chip spacing is reduced, and a better display effect is achieved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic cross-sectional structure of a Micro LED substrate structure according to the present invention;

FIG. 2 is a flow chart of a method for fabricating a Micro LED substrate structure according to the present invention;

FIG. 3 is a schematic top view of a conductive metal layer;

FIG. 4 is a schematic top view of a bonding metal layer;

FIG. 5 is a schematic diagram of a laser lift-off substrate to achieve a flexible Micro LED display.

Description of the symbols:

1-substrate, 2-conductive metal layer, 3-planarization layer, 4-insulating layer, 5-through hole, 6-bonding metal layer, 7-passivation layer, 8-reflection layer and 9-Light Emitting Diode (LED) chip.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a flexible Micro LED substrate structure and a preparation method thereof.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

As shown in fig. 1, the flexible Micro LED substrate structure of the present invention includes: the LED chip comprises asubstrate base plate 1, aconductive metal layer 2, aplanarization layer 3, an insulating layer 4, a throughhole 5, abonding metal layer 6 and anLED chip 9.

Specifically, theconductive metal layer 2 is fixed on thesubstrate base plate 1 and covers a part of thesubstrate base plate 1, an area of theconductive metal layer 2 is smaller than an area of thesubstrate base plate 1, and in this embodiment, theconductive metal layer 2 is made of copper Cu.

Theplanarization layer 3 covers the rest part of thesubstrate base plate 1, the thickness of theplanarization layer 3 is larger than that of theconductive metal layer 2, and theplanarization layer 3 is used for filling and leveling theconductive metal layer 2; theplanarization layer 3 is provided with a throughhole 5 corresponding to theconductive metal layer 2. The throughhole 5 is located right above theconductive metal layer 2, and the area of the through hole is smaller than or equal to that of theconductive metal layer 2. Preferably, the material of theplanarization layer 3 is Polyimide (PI).

The insulating layer 4 is arranged on theplanarization layer 3, and a through hole is formed in the position, corresponding to the throughhole 5, of the insulating layer 4.

Thebonding metal layer 6 penetrates through the via hole and the throughhole 5 to be connected with theconductive metal layer 2, and covers part of the insulating layer 4;

theLED chip 9 is disposed on thebonding metal layer 6 and connected to thebonding metal layer 6.

Further, the flexible Micro LED substrate structure further comprises apassivation layer 7. Specifically, thepassivation layer 7 is disposed on the insulating layer 4 and covers a portion of thebonding metal layer 6.

Still further, the flexible Micro LED substrate structure further comprises a reflective layer 8. Specifically, the reflective layer 8 is disposed on thepassivation layer 7 and surrounds the periphery of theLED chip 9. The light emitted by the LED chips is reflected by the reflecting layer 8, so that light crosstalk between adjacent chips is prevented.

As shown in fig. 2, the present invention further provides a method for manufacturing a flexible Micro LED substrate structure, where the method for manufacturing the flexible Micro LED substrate structure includes:

s100: forming aconductive metal layer 2 on asubstrate base plate 1;

s200: forming aplanarization layer 3 on theconductive metal layer 2 by a spin coating process;

s300: depositing an insulating layer 4 on theplanarization layer 3;

s400: forming a throughhole 5 on theplanarization layer 3 corresponding to theconductive metal layer 2, and forming a via hole on the insulating layer 4 corresponding to the throughhole 5 to expose theconductive metal layer 2;

s500: forming abonding metal layer 6 on the insulating layer 4, and connecting thebonding metal layer 6 with theconductive metal layer 2 through the via hole and the throughhole 5;

s600: bonding theLED chip 9 with thebonding metal layer 6;

s700: thebase substrate 1 is peeled off by means of laser peeling.

Further, after S500, the method for preparing the flexible Micro LED substrate further includes:

s510: depositing apassivation layer 7 on thebonding metal layer 6 through a composition process, exposing thebonding metal layer 6 to be bonded with the chip electrode, and covering the restbonding metal layers 6 by thepassivation layer 7;

s520: the reflective layer 8 is formed on thepassivation layer 7 by screen printing, thin film deposition, or inkjet printing.

Further, the step S400: the throughhole 5 is opened on theplanarization layer 3 corresponding to theconductive metal layer 2, and the via hole is opened on the insulating layer 4 corresponding to the throughhole 5, exposing theconductive metal layer 2, specifically including:

s401: forming a photoresist pattern on the insulating layer 4 and theplanarization layer 3;

s402: photoetching the insulating layer 4 and theplanarization layer 3, and removing part of the insulating layer 4 through dry etching or wet etching;

s403: removing part of theplanarization layer 3 by laser etching;

s404: and forming a throughhole 5 with the area less than or equal to the area of theconductive metal layer 2, and finally removing the photoresist.

Further, the step S500: forming abonding metal layer 6 on the insulating layer 4, penetrating through the via hole and the throughhole 5 to be connected with theconductive metal layer 2, specifically comprising:

s501: forming a negative photoresist pattern on the insulating layer 4;

s502: depositing a seed layer;

s503: connecting thebonding metal layer 6 with theconductive metal layer 2 by electroplating or chemical coating process;

s504: and stripping the metal on the photoresist by adopting a blue film, and removing the photoresist.

The present invention further provides another embodiment, in which the S500: forming abonding metal layer 6 on the insulating layer 4, penetrating through the via hole and the throughhole 5 to be connected with theconductive metal layer 2, specifically comprising:

s505: depositing a seed layer on the insulating layer 4;

s506: connecting thebonding metal layer 6 with theconductive metal layer 2 by electroplating or chemical coating process;

s507: forming a photoresist pattern on thebonding metal layer 6;

s508: and photoetching thebonding metal layer 6, removing redundant metal in a dry etching or wet etching mode, and finally removing the photoresist.

In addition, the preparation process of the flexible Micro LED substrate structure comprises the following steps:

as shown in fig. 3, aconductive metal layer 2 is formed on asubstrate 1 by a patterning process, theconductive metal layer 2 is made of Cu, the Cu is used as a cathode/anode signal line and can be connected to a Thin Film Transistor (TFT), and the thickness of the Cu can be set to 1-8 um according to the magnitude of a current-carrying resistance; the Cu metal layer can be finished by a sputter, an E-beam, electroplating, chemical plating and the like.

Forming aplanarization layer 3 on theconductive metal layer 2 through a spin coating process, wherein theplanarization layer 3 is Polyimide (PI) and has the thickness of 5-20 microns, and the flexible substrate is provided and is used for filling gaps among theconductive metal layers 2, so that the flatness is improved, and LED chip displacement is avoided during LED bonding;

depositing an insulating layer 4 on theplanarization layer 3 for increasing adhesion with thebonding metal layer 6, wherein the material may be one or more of silicon nitride, silicon oxide, and silicon oxynitride, and the thickness may be within a range

Forming a through hole penetrating through the insulating layer 4 by a dry etching process or a wet etching process, and then forming a throughhole 5 penetrating through the flat layer by laser etching on the basis of the through hole, wherein the diameter of the throughhole 5 is 1-6 um;

depositing a metal seed layer on the insulating layer 4, connecting the metal seed layer with theconductive metal layer 2 through the throughhole 5, wherein the metal seed layer can be formed by sputter, E-beam, PVD and other modes, the thickness range is 1nm to 1 μm, the metal material can be copper, aluminum, gold, titanium, silver, tin, nickel and the like, and can be one layer or multiple layers, then forming abonding metal layer 6, as shown in figure 4, thebonding metal layer 6 is connected with the metal seed layer through the throughhole 5 and serves as a cathode and anode signal connecting line, the material of thebonding metal layer 6 can be gold, aluminum, tin, nickel, titanium and the like, the metal layer can be formed by electroplating or chemical plating and the like, and then reserving a required pattern through a composition process, wherein the circularbonding metal layer 6 is connected with theconductive metal layer 2, and theother metal layers 6 are connected to serve as series;

depositing apassivation layer 7 on thebonding metal layer 6 by a composition process to expose the metal to be bonded with the chip electrode, covering the rest metal with thepassivation layer 7 to avoid electric leakage caused by contact with the chip, wherein the passivation layer is made of one or more of silicon nitride, silicon oxide and silicon oxynitride, and the thickness of the passivation layer can be within the range of the thickness

It should be noted that the patterning process includes processes such as thin film deposition, photoresist coating, photolithography, development, etching, photoresist removal, and metal stripping.

The reflecting layer 8 is formed through screen printing, film deposition or ink-jet printing and is used for increasing the light reflection of the LED chip, and the reflecting layer 8 can be one or more of silver, aluminum and other film layers to increase the light effect;

LED Bonding is carried out on theBonding metal layer 6; specifically, the LED chip and the bonding metal layer are bonded by flip chip bonding (flip chip bonding);

as shown in fig. 5, the panel is peeled from the substrate by means of laser lift-off, thereby realizing a flexible display.

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 method disclosed by the embodiment corresponds to the device disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the description of the method part.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.