WO2017107097A1 - Micro-led transfer method and manufacturing method - Google Patents

Micro-led transfer method and manufacturing method Download PDF

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Publication number
WO2017107097A1
WO2017107097A1 PCT/CN2015/098429 CN2015098429W WO2017107097A1 WO 2017107097 A1 WO2017107097 A1 WO 2017107097A1 CN 2015098429 W CN2015098429 W CN 2015098429W WO 2017107097 A1 WO2017107097 A1 WO 2017107097A1
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micro
leds
bonding layer
substrate
layer
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French (fr)
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Quanbo Zou
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Goertek Inc
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Goertek Inc
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Priority to CN201580085204.2A priority Critical patent/CN108431971B/en
Priority to US16/064,917 priority patent/US10566494B2/en
Priority to CN202110704729.7A priority patent/CN113421839B/en
Priority to PCT/CN2015/098429 priority patent/WO2017107097A1/en
Publication of WO2017107097A1 publication Critical patent/WO2017107097A1/en
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    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10HINORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H29/00Integrated devices, or assemblies of multiple devices, comprising at least one light-emitting semiconductor element covered by group H10H20/00
    • H10H29/01Manufacture or treatment
    • H10H29/03Manufacture or treatment using mass transfer of LEDs, e.g. by using liquid suspensions
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10HINORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/01Manufacture or treatment
    • H10H20/036Manufacture or treatment of packages
    • H10H20/0364Manufacture or treatment of packages of interconnections
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10HINORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H29/00Integrated devices, or assemblies of multiple devices, comprising at least one light-emitting semiconductor element covered by group H10H20/00
    • H10H29/80Constructional details
    • H10H29/85Packages
    • H10H29/8508Package substrates, e.g. submounts
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10PGENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/04Apparatus for manufacture or treatment
    • H10P72/0442Apparatus for placing on an insulating substrate, e.g. tape
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10PGENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/04Apparatus for manufacture or treatment
    • H10P72/0446Apparatus for mounting on conductive members, e.g. leadframes or conductors on insulating substrates
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10PGENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/70Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
    • H10P72/74Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10WGENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W90/00Package configurations
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10PGENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/70Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
    • H10P72/74Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
    • H10P72/7412Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support the auxiliary support including means facilitating the separation of a device or wafer from the auxiliary support
    • H10P72/7414Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support the auxiliary support including means facilitating the separation of a device or wafer from the auxiliary support the auxiliary support including means facilitating the selective separation of some of a plurality of devices from the auxiliary support
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10PGENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/70Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
    • H10P72/74Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
    • H10P72/7428Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support used to support diced chips prior to mounting
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10PGENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/70Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
    • H10P72/74Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
    • H10P72/744Details of chemical or physical process used for separating the auxiliary support from a device or a wafer
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10WGENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00Interconnections or connectors in packages
    • H10W72/01Manufacture or treatment
    • H10W72/0198Manufacture or treatment batch processes
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10WGENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00Interconnections or connectors in packages
    • H10W72/071Connecting or disconnecting
    • H10W72/073Connecting or disconnecting of die-attach connectors
    • H10W72/07302Connecting or disconnecting of die-attach connectors using an auxiliary member
    • H10W72/07304Connecting or disconnecting of die-attach connectors using an auxiliary member the auxiliary member being temporary, e.g. a sacrificial coating
    • H10W72/07307Connecting or disconnecting of die-attach connectors using an auxiliary member the auxiliary member being temporary, e.g. a sacrificial coating the auxiliary member being a temporary substrate, e.g. a removable substrate
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10WGENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00Interconnections or connectors in packages
    • H10W72/071Connecting or disconnecting
    • H10W72/073Connecting or disconnecting of die-attach connectors
    • H10W72/07331Connecting techniques
    • H10W72/07336Soldering or alloying
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10WGENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W72/00Interconnections or connectors in packages
    • H10W72/30Die-attach connectors
    • H10W72/351Materials of die-attach connectors
    • H10W72/352Materials of die-attach connectors comprising metals or metalloids, e.g. solders
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10WGENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
    • H10W90/00Package configurations
    • H10W90/701Package configurations characterised by the relative positions of pads or connectors relative to package parts
    • H10W90/721Package configurations characterised by the relative positions of pads or connectors relative to package parts of bump connectors
    • H10W90/724Package configurations characterised by the relative positions of pads or connectors relative to package parts of bump connectors between a chip and a stacked insulating package substrate, interposer or RDL

Definitions

  • the present invention relates to the technical field of micro-LED, and in particular, relates to a micro-LED transfer method and a method for manufacturing a micro-LED device
  • the micro-LED technology refers to the LED array of small size integrated on a substrate with high density.
  • the micro-LED technology is under development, and it is expected in the industry that a high-quality micro-LED product comes into the market.
  • High-quality micro-LED will have a deep affection on the conventional display products such as LCD/OLED that have already been put into the market.
  • US Patent No. US 8,333,860B 1 discloses a micro device transfer head and a method of transferring one or more micro devices to a receiving substrate.
  • This patent is hereby incorporated herein as a whole as a reference.
  • US Patent No. US 8,426,227B 1 discloses a micro light emitting diode LED and a method of forming an array of micro LEDs for transfer to a receiving substrate. This patent is hereby incorporated herein as a whole as a reference.
  • One object of this invention is to provide a new technical solution for micro-LED transfer.
  • a micro-LED transfer method comprising: coating a sacrificial layer on a carrier substrate, wherein micro-LEDs are bonded on the carrier substrate through a first bonding layer; patterning the sacrificial layer to expose micro-LEDs to be picked up; bonding the micro-LEDs to be picked up with a pickup substrate through a second bonding layer; removing the sacrificial layer by undercutting; lifting-off the micro-LEDs to be picked up from the carrier substrate; bonding the micro-LEDs on the pickup substrate with a receiving substrate through a third bonding layer; and lifting-off the micro-LEDs from the pickup substrate.
  • the first bonding layer and the second bonding layer are of solder layers and the second bonding layer is of polymer.
  • the lifting-off characteristics of the fist bonding layer and the second bonding layer are different from that of the second bonding layer.
  • the melting point of the first bonding layer is lower than 280°C, and the micro-LEDs to be picked up are lifted-off from the carrier substrate through heating.
  • the second bonding layer is a thermal release tape, or an UV curable and laser de-bondable film.
  • the sacrificial layer is a photo resist and the sacrificial layer is patterned through photo lithography.
  • the sacrificial layer is removed through etchant.
  • the side-length of the micro-LEDs is 1-100 ⁇ m.
  • the material of the pickup substrate includes one of glass, sapphire, quartz and silicon.
  • a second aspect of the present invention there is provided method for manufacturing a micro-LED device, comprising transferring micro-LEDs to a receiving substrate of the micro-LED device by using the micro-LED transfer method of the present invention.
  • the complicated pickup head is not necessary in this invention, and the technical solution of this invention is relatively simple. So, the task to be implemented by or the technical problem to be solved by the present invention has not been conceived or anticipated by a person skilled in the art and thus the present invention is a new solution.
  • Figure 1 is a flow chart of the method according to an embodiment of the present invention.
  • Figures 2-15 is a schematic diagram of an example for micro-LED transfer according to the present invention.
  • Figure 1 shows the flow chart of a micro-LED transfer method according to an embodiment of the present invention.
  • a sacrificial layer is coated on a carrier substrate, wherein micro-LEDs are bonded on the carrier substrate through a first bonding layer.
  • the micro-LEDs can be lateral micro-LEDs or vertical micro-LEDs.
  • the side-length of the micro-LEDs can be 1-100 ⁇ m.
  • the first bonding layer can be a solder layer.
  • the solder can be a metal or alloy with a relatively low melting point, or the combination thereof.
  • the melting point of the solder is lower than 280°C; more preferably, lower than 200°C; and even more preferably, lower than 160°C.
  • the sacrificial layer is patterned to expose micro-LEDs to be picked up.
  • the sacrificial layer can be a photo resist.
  • the sacrificial layer can be patterned through photo lithography.
  • a person skilled in the art can pattern the sacrificial layer through other approaches.
  • the micro-LEDs to be picked up are boned with a pickup substrate through a second bonding layer.
  • the material of the pickup substrate can include one of glass, sapphire, quartz and silicon.
  • the second bonding layer can be a thermal release tape, or an UV curable and laser de-bondable film.
  • the sacrificial layer is removed by undercutting.
  • the sacrificial layer can be removed by chemical undercutting.
  • an etchant can be used.
  • the etchant is a solvent such as acetone.
  • step S1500 the micro-LEDs to be picked up are lifted-off from the carrier substrate.
  • the micro-LEDs to be picked up can be lifted-off from the carrier substrate through heating.
  • the micro-LEDs on the pickup substrate are bonded with a receiving substrate through a third bonding layer.
  • step S1700 the micro-LEDs are lifted-off from the pickup substrate.
  • the micro-LEDs can remain on the second bonding layer (the pickup substrate) when being lifted-off from the first bonding layer (the carrier substrate)
  • the micro-LEDs can remain on the third bonding layer (the receiving substrate) when being lifted-off from the second bonding layer (the pickup substrate)
  • the lifting-off characteristic of the first bonding layer is different from that of the second bonding layer, so that the micro-LEDs can be transferred form the carrier substrate to the pickup substrate.
  • the lifting-off characteristic of the second bonding layer is different from that of the third bonding layer, so that the micro-LEDs can be transferred form the pickup substrate to the receiving substrate.
  • the lifting-off characteristic can include lifting-off temperature, lifting-off approach and so on.
  • the micro-LEDs can be lifted-off form the carrier substrate through heating, and can be lifted-off from the pickup substrate through a laser lifting-off.
  • the first bonding layer is a solder layer with low melting point
  • the second bonding layer is a polymer layer
  • the third bonding layer is a solder layer having a relatively high melting point after bonding.
  • the first bonding layer can be lifted-off through heating at a first temperature
  • the second bonding layer can be lifted-off thought heating at a second temperature, wherein the first temperature is lower than the second temperature.
  • the lifting-off can be performed through a contactless manner.
  • the micro-LEDs are kept on the pickup substrate or the receiving substrate through at least one of gravity, electrostatic force or magnetic force.
  • the electrostatic force can be applied via the pads or bonding layers on the pickup substrate or the receiving substrate, for example.
  • the magnetic force can be applied from the side of the pickup substrate or the receiving substrate, for example.
  • the present invention does not need the manufacturing of a complicated pickup head, and thus the technical solution of the present invention is relatively simple. This can further reduce the cost to a certain degree.
  • the pickup substrates rather than pickup head arrays can easily be used for a large scale processing. So, the yield can be improved by the present invention.
  • the present invention can improve the stability of pickup to a certain degree.
  • the present invention can further include a method for manufacturing a micro-LED device.
  • the manufacturing method comprises transfer micro-LEDs to a receiving substrate of the micro-LED device by using the above micro-LED transfer method.
  • the micro-LED device is a display screen device, for example, and the receiving substrate is a display panel or a display substrate, for example.
  • the present invention can further include the micro-LED device manufactured by the above manufacturing method and/or an electronics apparatus comprising said micro-LED device, such as a mobile phone, pad and so on.
  • Figures 2-15 show an example for micro-LED transfer according to the present invention.
  • red micro-LEDs 3r are bonded on the carrier substrate 1 through a first bonding layer 2.
  • the first bonding layer 2 is, for example, a solder layer or an adhesive tape layer.
  • the micro-LEDs can include p-metal, trench, dielectric and so on.
  • a sacrificial layer 4 is coated on the carrier substrate 1.
  • the sacrificial layer 4 covers the micro-LEDs 3r.
  • the sacrificial layer 4 is patterned to expose micro-LEDs 3r to be picked up, as indicated by the reference sign 5 in Figure 3.
  • the sacrificial layer 4 can photo resist, and the sacrificial layer 4 can be patterned through photo lithography.
  • the micro-LEDs 3r to be picked up are bonded onto a pickup substrate 7 through a second bonding layer 6.
  • the material of the second bonding layer 6 can be bonding polymer.
  • the bonding polymer can, for example, be an UV curable and laser de-bondable film (such as 3M LC5320 available in the market) , a thermal release tape, a high temperature UV tape (such as the UV releasable two-sides tape of Nitto Denko) , or a photo resist different for the sacrificial layer (which can be removed by using different solvent) .
  • the sacrificial layer 4 is removed by undercutting.
  • the sacrificial layer is removed by using solvent (etchant) such as acetone.
  • the micro-LEDs to be picked up are lifted-off from the carrier substrate.
  • the first bonding layer 2 is a solder layer with relatively low melting point. The solder of the first bonding layer 2 is melted through heating, and then the pickup substrate 7 is lifted up to lift-off the micro-LEDs to be picked up.
  • the red micro-LEDs 3r are picked up by the pickup substrate. As shown in Figures 8 and 9, the above steps can be repeated to pick up green micro-LEDs 3g and blue micro-LEDs 3b.
  • the micro-LEDs 3r on the pickup substrate are bonded with a receiving substrate 8 through the third bonding layer 9.
  • the micro-LEDs 3r are lifted-off from the pickup substrate 7.
  • the micro-LED 3r can be lifted-off by laser lifting-off or thermal release and so on.
  • the red micro-LED 3r are transferred to the receiving substrate 8.
  • the green micro-LEDs 3g can be transferred to the receiving substrate 8 by using the same approach.
  • the blue micro-LEDs 3b can be transferred to the receiving substrate 8 by using the same approach.
  • redundant micro-LEDs can be provided by using redundant technique. As such, when a certain micro-LED does not work, a redundant micro-LED corresponding to it can be used, thereby improving the quality of a display device.

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Abstract

A micro-LED transfer method and a manufacturing method are disclosed. The micro-LED transfer method comprises: coating a sacrificial layer on a carrier substrate, wherein micro-LEDs are bonded on the carrier substrate through a first bonding layer (S1100); patterning the sacrificial layer to expose micro-LEDs to be picked up (S1200); bonding the micro-LEDs to be picked up with a pickup substrate through a second bonding layer (S1300); removing the sacrificial layer by undercutting (S1400); lifting-off the micro-LEDs to be picked up from the carrier substrate (S1500); bonding the micro-LEDs on the pickup substrate with a receiving substrate through a third bonding layer (S1600); and lifting-off the micro-LEDs from the pickup substrate(S1700).

Description

MICRO-LED TRANSFER METHOD AND MANUFACTURING METHOD FIELD OF THE INVENTION
The present invention relates to the technical field of micro-LED, and in particular, relates to a micro-LED transfer method and a method for manufacturing a micro-LED device
BACKGROUND OF THE INVENTION
The micro-LED technology refers to the LED array of small size integrated on a substrate with high density. Currently, the micro-LED technology is under development, and it is expected in the industry that a high-quality micro-LED product comes into the market. High-quality micro-LED will have a deep affection on the conventional display products such as LCD/OLED that have already been put into the market.
Until now, how to transfer micro-LEDs to a receiving substrate of a micro-LED device has always been a technical task to be improved by a technician.
In the prior art, a pickup head is used to transfer micro-LEDs. The approaches using pickup heads are relatively complicated and have problems in the aspects of yield and stability.
For example, the US Patent No. US 8,333,860B 1 discloses a micro device transfer head and a method of transferring one or more micro devices to a receiving substrate. This patent is hereby incorporated herein as a whole as a reference.
The US Patent No. US 8,426,227B 1discloses a micro light emitting diode LED and a method of forming an array of micro LEDs for transfer to a receiving substrate. This patent is hereby incorporated herein as a whole as a reference.
SUMMARY OF THE INVENTION
One object of this invention is to provide a new technical solution for micro-LED transfer.
According to a first aspect of the present invention, there is provided a micro-LED transfer method, comprising: coating a sacrificial layer on a carrier substrate, wherein micro-LEDs are bonded on the carrier substrate through a first bonding layer; patterning the sacrificial layer to expose micro-LEDs to be picked up; bonding the micro-LEDs to be picked up with a pickup substrate through a second bonding layer; removing the sacrificial layer by undercutting; lifting-off the micro-LEDs to be picked up from the carrier substrate; bonding the micro-LEDs on the pickup substrate with a receiving substrate through a third bonding layer; and lifting-off the micro-LEDs from the pickup substrate.
Preferably, the first bonding layer and the second bonding layer are of solder layers and the second bonding layer is of polymer.
Preferably, the lifting-off characteristics of the fist bonding layer and the second bonding layer are different from that of the second bonding layer.
Preferably, the melting point of the first bonding layer is lower than 280℃, and the micro-LEDs to be picked up are lifted-off from the carrier substrate through heating.
Preferably, the second bonding layer is a thermal release tape, or an UV curable and laser de-bondable film.
Preferably, the sacrificial layer is a photo resist and the sacrificial layer is patterned through photo lithography.
Preferably, the sacrificial layer is removed through etchant.
Preferably, the side-length of the micro-LEDs is 1-100μm.
Preferably, the material of the pickup substrate includes one of glass, sapphire, quartz and silicon.
According to a second aspect of the present invention, there is provided method for manufacturing a micro-LED device, comprising transferring micro-LEDs to a receiving substrate of the micro-LED device by using the micro-LED transfer method of the present invention.
Compared with the prior art, the complicated pickup head is not necessary in this invention, and the technical solution of this invention is relatively simple. So, the task to be implemented by or the technical problem to be solved by the present invention has not been conceived or anticipated by a person skilled in the art and thus the present invention is a  new solution.
Further features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments according to the present invention with reference to the attached drawings.
BRIEF DISCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description thereof, serve to explain the principles of the invention.
Figure 1 is a flow chart of the method according to an embodiment of the present invention.
Figures 2-15 is a schematic diagram of an example for micro-LED transfer according to the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Various exemplary embodiments of the present invention will now be described in detail with reference to the drawings. It should be noted that the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise.
The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.
Techniques, methods and apparatus as known by one of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.
In all of the examples illustrated and discussed herein, any specific values should be interpreted to be illustrative only and non-limiting. Thus, other examples of the exemplary embodiments could have different values.
Notice that similar reference numerals and letters refer to similar items in the  following figures, and thus once an item is defined in one figure, it is possible that it need not be further discussed for following figures.
Below, the embodiments and examples will be described with reference to the accompany figures.
Figure 1 shows the flow chart of a micro-LED transfer method according to an embodiment of the present invention.
As show in Figure 1, at step S1100, a sacrificial layer is coated on a carrier substrate, wherein micro-LEDs are bonded on the carrier substrate through a first bonding layer.
For example, the micro-LEDs can be lateral micro-LEDs or vertical micro-LEDs. The side-length of the micro-LEDs can be 1-100μm.
The first bonding layer can be a solder layer. The solder can be a metal or alloy with a relatively low melting point, or the combination thereof. Preferably, the melting point of the solder is lower than 280℃; more preferably, lower than 200℃; and even more preferably, lower than 160℃.
At step S1200, the sacrificial layer is patterned to expose micro-LEDs to be picked up.
The sacrificial layer can be a photo resist. The sacrificial layer can be patterned through photo lithography. Of course, a person skilled in the art can pattern the sacrificial layer through other approaches.
At step S1300, the micro-LEDs to be picked up are boned with a pickup substrate through a second bonding layer.
The material of the pickup substrate can include one of glass, sapphire, quartz and silicon. The second bonding layer can be a thermal release tape, or an UV curable and laser de-bondable film.
At step S1400, the sacrificial layer is removed by undercutting.
For example, the sacrificial layer can be removed by chemical undercutting. For example, an etchant can be used. The etchant is a solvent such as acetone.
At step S1500, the micro-LEDs to be picked up are lifted-off from the carrier substrate.
For example, in the situation where the first bonding layer has a relatively low melting point, the micro-LEDs to be picked up can be lifted-off from the carrier substrate through heating.
At step S1600, the micro-LEDs on the pickup substrate are bonded with a receiving substrate through a third bonding layer.
At step S1700, the micro-LEDs are lifted-off from the pickup substrate.
Based on the teaching of the present invention, a person skilled in the art would easily understand that the technical solution of the present invention per se has already indicated that the micro-LEDs can remain on the second bonding layer (the pickup substrate) when being lifted-off from the first bonding layer (the carrier substrate) , and the micro-LEDs can remain on the third bonding layer (the receiving substrate) when being lifted-off from the second bonding layer (the pickup substrate) . For example, the lifting-off characteristic of the first bonding layer is different from that of the second bonding layer, so that the micro-LEDs can be transferred form the carrier substrate to the pickup substrate. Furthermore, the lifting-off characteristic of the second bonding layer is different from that of the third bonding layer, so that the micro-LEDs can be transferred form the pickup substrate to the receiving substrate. The lifting-off characteristic can include lifting-off temperature, lifting-off approach and so on.
For example, the micro-LEDs can be lifted-off form the carrier substrate through heating, and can be lifted-off from the pickup substrate through a laser lifting-off.
In an example, the first bonding layer is a solder layer with low melting point, the second bonding layer is a polymer layer, and the third bonding layer is a solder layer having a relatively high melting point after bonding. In this situation, the first bonding layer can be lifted-off through heating at a first temperature, and the second bonding layer can be lifted-off thought heating at a second temperature, wherein the first temperature is lower than the second temperature.
In a preferable embodiment, alternatively, the lifting-off can be performed through a contactless manner. For example, when lifting-off, the micro-LEDs are kept on the pickup substrate or the receiving substrate through at least one of gravity, electrostatic force or  magnetic force. The electrostatic force can be applied via the pads or bonding layers on the pickup substrate or the receiving substrate, for example. The magnetic force can be applied from the side of the pickup substrate or the receiving substrate, for example.
In the case where the present invention has already taught that the first bonding layer and the second bonding layer are to be lifted-off individually, this teaching is sufficient for a person skilled in the art to readily conceive a lot of manners to individually lift-off the bonding layers, even if some of the manners are inventive. Thus, the detailed descriptions for various specific lifting-off approaches are omitted in this specification.
Compared with the technique of pickup head in the prior art, the present invention does not need the manufacturing of a complicated pickup head, and thus the technical solution of the present invention is relatively simple. This can further reduce the cost to a certain degree.
Furthermore, the pickup substrates rather than pickup head arrays can easily be used for a large scale processing. So, the yield can be improved by the present invention.
Furthermore, compared with the electrostatic pickup of a pickup head, the present invention can improve the stability of pickup to a certain degree.
In another embodiment, the present invention can further include a method for manufacturing a micro-LED device. The manufacturing method comprises transfer micro-LEDs to a receiving substrate of the micro-LED device by using the above micro-LED transfer method. The micro-LED device is a display screen device, for example, and the receiving substrate is a display panel or a display substrate, for example.
Furthermore, the present invention can further include the micro-LED device manufactured by the above manufacturing method and/or an electronics apparatus comprising said micro-LED device, such as a mobile phone, pad and so on.
Figures 2-15 show an example for micro-LED transfer according to the present invention.
As shown in Figure 2, red micro-LEDs 3r are bonded on the carrier substrate 1 through a first bonding layer 2. The first bonding layer 2 is, for example, a solder layer or an adhesive tape layer. The micro-LEDs can include p-metal, trench, dielectric and so on.
As shown in Figure 3, a sacrificial layer 4 is coated on the carrier substrate 1. The sacrificial layer 4 covers the micro-LEDs 3r. The sacrificial layer 4 is patterned to expose micro-LEDs 3r to be picked up, as indicated by the reference sign 5 in Figure 3. The sacrificial layer 4 can photo resist, and the sacrificial layer 4 can be patterned through photo lithography.
As shown in Figure 4, the micro-LEDs 3r to be picked up are bonded onto a pickup substrate 7 through a second bonding layer 6.
The material of the second bonding layer 6 can be bonding polymer. The bonding polymer can, for example, be an UV curable and laser de-bondable film (such as 3M LC5320 available in the market) , a thermal release tape, a high temperature UV tape (such as the UV releasable two-sides tape of Nitto Denko) , or a photo resist different for the sacrificial layer (which can be removed by using different solvent) .
As shown in Figure 5, the sacrificial layer 4 is removed by undercutting. For example, the sacrificial layer is removed by using solvent (etchant) such as acetone.
As shown in Figure 6, the micro-LEDs to be picked up are lifted-off from the carrier substrate. For example, the first bonding layer 2 is a solder layer with relatively low melting point. The solder of the first bonding layer 2 is melted through heating, and then the pickup substrate 7 is lifted up to lift-off the micro-LEDs to be picked up.
As shown in Figure 7, the red micro-LEDs 3r are picked up by the pickup substrate. As shown in Figures 8 and 9, the above steps can be repeated to pick up green micro-LEDs 3g and blue micro-LEDs 3b.
As shown in Figure 10, the micro-LEDs 3r on the pickup substrate are bonded with a receiving substrate 8 through the third bonding layer 9. As shown in Figure 11, the micro-LEDs 3r are lifted-off from the pickup substrate 7. For example, the micro-LED 3r can be lifted-off by laser lifting-off or thermal release and so on. As such, the red micro-LED 3r are transferred to the receiving substrate 8.
As shown in Figures 12 and 13, the green micro-LEDs 3g can be transferred to the receiving substrate 8 by using the same approach.
As shown in Figures 14 and 15, the blue micro-LEDs 3b can be transferred to the  receiving substrate 8 by using the same approach.
In an example, in order to remedy the faults of certain micro-LEDs, redundant micro-LEDs can be provided by using redundant technique. As such, when a certain micro-LED does not work, a redundant micro-LED corresponding to it can be used, thereby improving the quality of a display device.
Although some specific embodiments of the present invention have been demonstrated in detail with examples, it should be understood by a person skilled in the art that the above examples are only intended to be illustrative but not to limit the scope of the present invention. It should be understood by a person skilled in the art that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the attached claims.

Claims (10)

  1. A micro-LED transfer method, comprising:
    coating a sacrificial layer on a carrier substrate, wherein micro-LEDs are bonded on the carrier substrate through a first bonding layer;
    patterning the sacrificial layer to expose micro-LEDs to be picked up;
    bonding the micro-LEDs to be picked up with a pickup substrate through a second bonding layer;
    removing the sacrificial layer by undercutting;
    lifting-off the micro-LEDs to be picked up from the carrier substrate;
    bonding the micro-LEDs on the pickup substrate with a receiving substrate through a third bonding layer; and
    lifting-off the micro-LEDs from the pickup substrate.
  2. The method according to claim 1, wherein the first bonding layer and the second bonding layer are of solder layers and the second bonding layer is of polymer.
  3. The method according to claim 1 or 2, wherein the lifting-off characteristics of the fist bonding layer and the second bonding layer are different from that of the second bonding layer.
  4. The method according to anyone of claims 1-3, wherein the melting point of the first bonding layer is lower than 280℃, and the micro-LEDs to be picked up are lifted-off from the carrier substrate through heating.
  5. The method according to anyone of claims 1-4, wherein the second bonding layer is a thermal release tape, or an UV curable and laser de-bondable film.
  6. The method according to anyone of claims 1-5, wherein the sacrificial layer is a photo resist and the sacrificial layer is patterned through photo lithography.
  7. The method according to anyone of claims 1-6, wherein the sacrificial layer is removed through etchant.
  8. The method according to anyone of claims 1-7, wherein the side-length of the micro-LEDs is 1-100μm.
  9. The method according to anyone of claims 1-8, wherein the material of the pickup substrate includes one of glass, sapphire, quartz and silicon.
  10. A method for manufacturing a micro-LED device, comprising transferring micro-LEDs to a receiving substrate of the micro-LED device by using the method according to anyone of claims 1-9.
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CN202110704729.7A CN113421839B (en) 2015-12-23 2015-12-23 Micro light emitting diode transfer method and manufacturing method
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