CN111293070A - Bipolar electrostatic suction head of miniature light-emitting diode and array thereof - Google Patents

Abstract

The invention provides a micro light-emitting diode bipolar electrostatic suction head and an array thereof, wherein the bipolar electrostatic suction head comprises a first electrode which is circular and is not completely closed, a second electrode which is circular and is positioned in the first electrode, a gap positioned between the first electrode and the second electrode, a first dielectric layer filled in the gap, a first electrode connecting wire connected with the first electrode, a second electrode connecting wire connected with the second electrode and a second dielectric layer, wherein the second dielectric layer covers the first electrode, the second electrode, the first dielectric layer, the first electrode connecting wire and the second electrode connecting wire, and the first electrode and the second electrode simultaneously adsorb one micro light-emitting diode. The invention adopts the bipolar electrostatic suction head and utilizes the electrostatic adsorption force to carry out mass transfer on the micro light-emitting diode, and simplifies the connecting structure of the electrostatic suction head and the electrostatic generator, thereby reducing the gap (gap) between the suction head and the surface of the micro light-emitting diode and carrying out high-efficiency transfer on the micro device by utilizing the electrostatic suction head.

Description

A miniature light-emitting diode bipolar electrostatic suction head and its array

technical field

The invention relates to the technical field of miniature light-emitting diodes, in particular to a bipolar electrostatic suction head of a miniature light-emitting diode and an array thereof.

Background technique

The transfer and packaging of micro-devices such as Micro LED and MEMS has always been an important factor restricting their large-scale commercial use. At present, the transfer of micro-devices mostly adopts van der Waals force, such as transfer printing technology, which usually requires the transfer head. Coating materials with a certain viscosity, such as PDMS, requires a large external force, such as vacuum bonding, gravity extrusion, etc., to ensure that the viscous material on the transfer head is in contact with the micro device during transfer. Therefore, when the micro device is placed on the After the backplane is driven, a large amount of viscous material remains on its surface, which adversely affects the electrical properties of the micro-device.

When the micro device is transferred by the electrostatic adsorption force generated by the static charge of the opposite sex, the surface of the micro device will not be polluted. In addition, the speed of electrostatic discharge is relatively fast, which greatly improves the transfer efficiency.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a miniature light-emitting diode bipolar electrostatic suction head and an array thereof that increase the electrostatic suction force and simplify the connection between the electrostatic suction head and the electrostatic generator.

The present invention provides a miniature light-emitting diode bipolar electrostatic suction head, which comprises a circular and incompletely closed first electrode, a circular second electrode located inside the first electrode, a first electrode and a second circular electrode. A gap between electrodes, a first dielectric layer filled in the gap, a first electrode connection line connected to the first electrode, a second electrode connection line connected to the second electrode, and the second dielectric layer, wherein the The second dielectric layer covers the first electrode, the second electrode, the first dielectric layer, the first electrode connection line and the second electrode connection line, and the first electrode and the second electrode simultaneously adsorb a micro light-emitting diode .

Preferably, the second electrode connecting wire extends from the incompletely closed part of the first electrode, and the extending direction of the first electrode connecting wire is opposite to the extending direction of the second electrode connecting wire.

Preferably, the thickness of the first dielectric layer is not less than the thicknesses of the first electrode and the second electrode.

Preferably, the thickness of the second dielectric layer is not less than

Preferably, both the first electrode and the second electrode are made of chromium and gold composite layer or titanium or aluminum.

The present invention also provides a miniature light-emitting diode bipolar electrostatic suction head array, which includes bipolar electrostatic suction heads arranged in M rows and N columns, a first contact electrode, a second contact electrode, and multiple electrodes connected to the first contact electrode. A first connection line, a plurality of second connection lines connected to the second contact electrode, a plurality of electrode lead holes disposed in the first contact electrode and the second contact electrode, attached to the first contact electrode and passed through The first terminal connected by the electrode lead hole and the second terminal attached to the second contact electrode and connected through the electrode lead hole, wherein a plurality of first connection lines and a plurality of second connection lines are connected to each row in an alternating manner, respectively The first electrode connection line and the second electrode connection line of the bipolar electrostatic suction head.

Preferably, a first voltage source connected to the first terminal and a second voltage source connected to the second terminal are also included.

Preferably, the micro-LED bipolar electrostatic suction head array is located on the transport substrate, the second terminal, the first voltage source, the second terminal and the second voltage source are all arranged on the back of the transport substrate, and the bipolar electrostatic suction head is formed on the transport substrate the front side of the substrate.

Preferably, the micro light emitting diode bipolar electrostatic suction head array further includes a filled conductive layer disposed in each electrode lead hole and an elastic material layer located in the conductive layer, the conductive layer connecting the first contact electrode and the first terminal and the second Contact the electrode and the second terminal.

The invention adopts a bipolar electrostatic suction head and utilizes electrostatic adsorption force to transfer a large amount of micro-LEDs, and simplifies the connection structure of the electrostatic suction head and the electrostatic generator, thereby reducing the gap between the suction head and the surface of the micro-LEDs , the use of electrostatic suction heads to efficiently transfer micro-devices.

Description of drawings

1 is a schematic structural diagram of a miniature light-emitting diode bipolar electrostatic suction head of the present invention;

FIG. 2 is a cross-sectional view of the miniature light-emitting diode bipolar electrostatic suction head shown in FIG. 1;

3 is a schematic structural diagram of an array of miniature light-emitting diode bipolar electrostatic suction heads of the present invention;

FIG. 4 is a schematic structural diagram of the back surface of the miniature light-emitting diode bipolar electrostatic suction head array shown in FIG. 3;

FIG. 5 is a schematic diagram of the electrode lead holes of the micro-LED bipolar electrostatic suction head array shown in FIG. 3;

FIG. 6 is a schematic structural diagram of the micro-LED bipolar electrostatic suction head array shown in FIG. 3 adsorbing the micro-LEDs.

Detailed ways

Below in conjunction with the accompanying drawings and specific embodiments, the present invention will be further clarified. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Modifications of equivalent forms all fall within the scope defined by the appended claims of this application.

In order to keep the drawings concise, the drawings only schematically show the parts related to the present invention, and they do not represent its actual structure as a product. In addition, in order to make the drawings concise and easy to understand, in some drawings, only one of the components having the same structure or function is schematically shown, or only one of them is marked. As used herein, "one" not only means "only one", but also "more than one".

The present invention discloses a miniature light-emitting diode bipolar electrostatic suction head 100 , as shown in FIG. 1 and FIG. 2 , the bipolar electrostatic suction head 100 includes a first electrode 10 which is annular and not completely closed, and is located in the first electrode 10 . The inner and circular second electrode 20 , the gap 30 between the first electrode 10 and the second electrode 20 , the first dielectric layer 40 filled in the gap 30 , the first electrode connected to the first electrode 10 The connection line 11 , the second electrode connection line 21 connected to the second electrode 20 , and the second dielectric layer 50 , wherein the second dielectric layer 50 covers the first electrode 10 , the second electrode 20 , and the first dielectric layer 40. On the first electrode connection line 11 and the second electrode connection line 21, wherein the first electrode 10 and the second electrode 20 simultaneously adsorb a miniature light-emitting diode.

Both the first electrode 10 and the second electrode 20 are circular, which increases the suction force and reduces the edge discharge phenomenon.

The second electrode connecting wire 21 extends from the incompletely closed part of the first electrode 10 , and the extending direction of the first electrode connecting wire 11 is opposite to that of the second electrode connecting wire 21 .

Wherein, the thickness of the first dielectric layer 40 is not less than the thickness of the first electrode 10 and the second electrode 20, and the thickness of the second dielectric layer 50 is not less than

The first electrode 10 and the second electrode 20 are both made of chromium and gold composite layers or metals such as titanium or aluminum, which have good bonding force with the transport substrate 1 and have better oxidation resistance and corrosion resistance.

The present invention also discloses a miniature light-emitting diode bipolar electrostatic suction head array, as shown in FIG. 3 and FIG. 4 , which includes bipolar electrostatic suction heads 100 arranged in M rows and N columns, a first contact electrode 61 , a second The contact electrode 62 , a plurality of first connection lines 63 connected to the first contact electrode 61 , and a plurality of second connection lines 64 connected to the second contact electrode 62 are provided on the first contact electrode 61 and the second contact electrode 62 A plurality of electrode lead holes 612 inside, the first terminal 71 attached to the first contact electrode 61 and connected through the electrode lead hole 612, the second contact electrode 62 attached to the second contact electrode 62 and connected through the electrode lead hole 612. _A terminal 72, a first voltage source VA connected to the first terminal 71, and a second voltage source _VB connected to the second terminal 72, wherein the plurality of first connection lines 63 and the plurality of second connection lines 64 are alternated. The first electrode connection lines 11 and the second electrode connection lines 21 of each row of bipolar electrostatic suction heads 100 are respectively connected in a manner.

Wherein "a plurality of first connection lines 63 and a plurality of second connection lines 64 are respectively connected to the first electrode connection lines 11 and the second electrode connection lines 21 of each row of bipolar electrostatic suction heads 100 in an alternating manner" means the first The first electrode connection lines 11 of one row of bipolar electrostatic suction heads 100 are all connected to the uppermost first connection wire 63 , the second electrode connection lines 21 of the first row of bipolar electrostatic suction heads 100 and the second row of bipolar electrostatic suction heads are connected to the topmost first connection wire 63 . The first electrode connection lines 11 of the suction head 100 are respectively connected on opposite sides of the second connection line 64 , the second electrode connection lines 21 of the second row of bipolar electrostatic suction heads 100 and the third row of bipolar electrostatic suction heads 100 are respectively connected. The first electrode connection lines 11 are respectively connected on opposite sides of the first connection lines 63 in the second row, and so on, the second electrode connection lines 21 of the bipolar electrostatic suction heads 100 in the last row are connected to the first connection at the bottom line 63; or the first electrode connection lines 11 of the first row of bipolar electrostatic suction heads 100 are all connected to the uppermost second connection wire 64, the second electrode connection lines 21 of the first row of bipolar electrostatic suction heads 100 and the second connection line 64 on the uppermost The first electrode connecting lines 11 of the two rows of bipolar electrostatic suction heads 100 are respectively connected to opposite sides of the topmost first connecting wire 64 , and the second electrode connecting lines 21 and the third The first electrode connecting lines 11 of the bipolar electrostatic suction heads 100 in the row are respectively connected to opposite sides of the second connecting lines 64 in the second row, and so on, the second electrode connecting lines 21 of the bipolar electrostatic suction heads 100 in the last row are respectively connected Connected to the lowermost second connection line 64 .

As shown in FIG. 5 , the micro-LED bipolar electrostatic suction head array further includes a filled conductive layer 613 disposed in each electrode lead hole 612 and an elastic material layer 614 located in the conductive layer 613, and the conductive layer 613 is connected to the first contact The electrode 61 and the first terminal 71 and the second contact electrode 62 and the second terminal 72 realize the electrical connection between the first contact electrode 61 and the first terminal 71 and the second contact electrode 62 and the second terminal 72 .

The elastic material is arranged in the electrode lead hole, which reduces the stress in the contact electrode and prolongs the service life of the electrostatic suction head.

As shown in FIG. 6 , the micro-LED bipolar electrostatic suction head array is located on the transport substrate 1, and the micro LEDs 200 arranged in the array are located on the temporary storage substrate 2. When the micro LED 200 needs to be transported, the bipolar electrostatic suction head The first electrode 10 and the second electrode 20 of 100 adsorb a micro light-emitting diode 200 at the same time.

_The first terminal 71 , the first voltage source VA , the second terminal 72 and the second voltage source _VB are all disposed on the backside of the transfer substrate 1 .

_The second terminal 72, the first voltage source VA, the second terminal 72 and the second voltage source _VB are collectively referred to as the positive and negative electrodes of the electrostatic generator. By arranging the electrostatic generator on the back side, the bipolar electrostatic suction head is reduced. Gap value between 100 and 200 for micro LEDs.

The bipolar electrostatic suction head 100 is formed on the front surface of the transfer substrate 1 .

The present invention also discloses a method for manufacturing a miniature light-emitting diode bipolar electrostatic suction head array, comprising the following steps:

S1: First, use CNC machining technology (ie, computer digital control precision machining) or laser technology to form electrode lead holes 612 on the first contact electrode 61 and the second contact electrode 62 of the transfer substrate 1; After cleaning the transport substrate 1 in an acidic or alkaline cleaning agent, rinse with water, and then in an organic solution (such as acetone or isopropanol), and assisted by ultrasound;

S2: First, a conductive layer 613 is formed in the electrode lead hole 612 by using an electroless plating technique (such as electroless silver plating); then an elastic material, such as PDMS (polydimethylsilicon Oxane, polydimethylsiloxane);

S3: forming the first terminal 71 and the second terminal 71 on the back surface of the transfer substrate 1;

S4 : The first electrode 10 and the second electrode 20 connected to the first contact electrode 61 and the second contact electrode 62 , respectively, are formed on the front surface of the transfer substrate 1 .

Wherein, the specific method of step S3 is:

S31: First spin-coat the negative photoresist on the backside of the transport substrate 1, then expose and develop;

S32: use plasma cleaning equipment to clean the exposed transport substrate 1;

S33: use physical vapor deposition to deposit a metal film on the back of the transport substrate 1, and the material of the metal film is single-layer Ti or Cr/Au (wherein Au is above Cr);

S34 : The metal film is peeled off by a lift-off method to form target patterns, that is, the first terminals 71 and the second terminals 72 .

The specific method of step S4 is:

S41: uniformly coat a negative photoresist on the front surface of the transport substrate 1 with a thickness of ≥2 μm, and then perform exposure and development; finally, use a plasma cleaning device to clean the exposed transport substrate 1;

S42: Use physical vapor deposition (such as electron beam evaporation, magnetron sputtering and other film forming techniques) to deposit a metal film layer, and the material of the metal film layer is Ti/Cu (where Cu is above Ti) or Cr/Au (wherein Au is above Cr) and other metals with better bonding force with the transport substrate 1, the thickness of which is

S43: peeling off the metal film layer by using the peeling lift-off method to form a semi-closed target pattern, that is, the first electrode 10;

S44 : deposit an inorganic dielectric layer (the material of which is SiNx, TiO ₂ or Al ₂ O ₃ , etc.) on the transfer substrate 1 by a vapor deposition method, the thickness of which is equal to the thickness of the first electrode 10 , and then perform sizing, exposure and development , and finally dry-etch the inorganic dielectric layer so that only the target position exists;

S45: repeating the above steps S41 to S44 to form the second electrode 20;

S46: Use the vapor deposition method to deposit an inorganic dielectric layer such as SiNx, _TiO2 or _{Al2O3 on} the front side or a spin-coating organic dielectric layer on the substrate, that is, to form a second dielectric layer 50, the thickness of which is not less than

The invention adopts a bipolar electrostatic suction head and utilizes electrostatic adsorption force to transfer a large amount of micro-LEDs, and simplifies the connection structure of the electrostatic suction head and the electrostatic generator, thereby reducing the gap between the suction head and the surface of the micro-LEDs , the use of electrostatic suction heads to efficiently transfer micro-devices.

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations (such as quantity, shape, etc.) can be performed on the technical solutions of the present invention. , position, etc.), these equivalent transformations all belong to the protection scope of the present invention.

Claims (9)

1. A miniature light-emitting diode bipolar electrostatic suction head, characterized in that it comprises a circular first electrode that is not fully closed, a circular second electrode located inside the first electrode, a circular second electrode located in the first electrode a gap between the gap and the second electrode, a first dielectric layer filled in the gap, a first electrode connection line connected to the first electrode, a second electrode connection line connected to the second electrode, and a second dielectric layer, Wherein, the second dielectric layer covers the first electrode, the second electrode, the first dielectric layer, the first electrode connection line and the second electrode connection line, and the first electrode and the second electrode simultaneously adsorb one Miniature light-emitting diodes. 2 . The bipolar electrostatic suction head for miniature light-emitting diodes according to claim 1 , wherein the second electrode connecting line extends out from the incompletely closed part of the first electrode, and the extension direction of the first electrode connecting line is the same as that of the second electrode. 3 . The extending directions of the electrode connecting lines are opposite. 3 . The bipolar electrostatic suction head for miniature light emitting diodes according to claim 1 , wherein the thickness of the first dielectric layer is not less than the thicknesses of the first electrode and the second electrode. 4 . 4. The miniature light-emitting diode bipolar electrostatic suction head according to claim 1, wherein the thickness of the second dielectric layer is not less than

5. The miniature light-emitting diode bipolar electrostatic suction head according to claim 1, wherein the first electrode and the second electrode are both made of chromium and gold composite layer or titanium or aluminum. 6. A miniature light-emitting diode bipolar electrostatic suction head array, characterized in that it comprises bipolar electrostatic suction heads arranged in M rows and N columns, a first contact electrode, a second contact electrode, and a connection with the first contact electrode. A plurality of first connection lines, a plurality of second connection lines connected to the second contact electrodes, a plurality of electrode lead holes disposed in the first contact electrodes and the second contact electrodes, and attached to the first contact electrodes And the first terminal connected through the electrode lead hole and the second terminal attached to the second contact electrode and connected through the electrode lead hole, wherein the plurality of first connection lines and the plurality of second connection lines are respectively connected in an alternating manner The first electrode connection line and the second electrode connection line of the bipolar electrostatic suction heads in each row; the bipolar electrostatic suction heads are the miniature light-emitting diode bipolar electrostatic suction heads according to any one of claims 1-5. 7 . The micro-LED bipolar electrostatic suction head array according to claim 6 , further comprising a first voltage source connected to the first terminal and a second voltage source connected to the second terminal. 8 . 8. The miniature light emitting diode bipolar electrostatic suction head array according to claim 7, wherein the miniature light emitting diode bipolar electrostatic suction head array is located on the transport substrate, the second terminal, the first voltage source, the second terminal and the The second voltage sources are all arranged on the backside of the transfer substrate, and the bipolar electrostatic suction head is formed on the front side of the transfer substrate. 9 . The micro LED bipolar electrostatic suction head array according to claim 6 , wherein the micro LED bipolar electrostatic suction head array further comprises a filled conductive layer disposed in each electrode lead hole and a conductive layer located in the conductive layer. 10 . The inner elastic material layer, the conductive layer connects the first contact electrode and the first terminal and the second contact electrode and the second terminal.

Images