CN109671651B - A kind of ultrasound release type Micro-LED flood tide transfer method - Google Patents

Abstract

It is a kind of ultrasound release type Micro-LED flood tide transfer method include the following steps, A, transfer prepares, transfer base substrate is horizontal positioned, the lower surface high resilience film of transfer base substrate, chip is adhered to the surface of elastic membrane, it is equipped with supersonic generation unit in the position for the upper surface for laying flat transfer base substrate, ultrasonic transducer is installed on the supersonic generation unit surface；B, somewhere wafer alignment on selection alignment, supersonic generation unit and transfer base substrate is realized by ultrasonic transducer and is directly contacted；C, deformation discharges, and in certain specific positions, the elastic membrane at this is deformed for ultrasonication, is arched upward in back surface of the wafer, so that chip is detached from transfer base substrate, falls in target substrate under the effect of gravity；This method can realize being released effectively for laser-light transparent and the chip on nontransparent transfer base substrate, avoid the methods of conventional laser removing/laser heating removing heat affecting unfavorable to chip and transfer base substrate.

Description

An Ultrasonic Release Micro-LED Mass Transfer Method

technical field

The invention relates to the field of semiconductor optoelectronic technology, in particular to a Micro-LED mass transfer method.

Background technique

LED (Light Emitting Diode) is a semiconductor electronic component that can emit light. It has the advantages of high energy conversion efficiency, short reaction time, and long service life. It is obtained by forming and arraying, and the size is only 1-10 μm. Due to the advantages of LED display technology, Micro-LED is increasingly used in display occasions, such as: micro projection (virtual reality equipment), small screen display (smart wearable device), medium and large screen display (TV), Large screen display (outdoor display), etc. However, the manufacturing process of ultra-high-resolution Micro-LED displays still restricts the application of Micro-LEDs to the above-mentioned purposes. Compared with OLED (organic light-emitting diode), a large-area light-emitting surface can be easily produced by printing and other inexpensive production methods. To make a large-size, high-resolution Micro-LED display requires millions or tens of millions of micron-scale Micro-LED chips of different sizes are arranged and assembled (mass transfer), which brings huge manufacturing cost consumption. Mass transfer requires precise grasping of micron-sized Micro-LED chips from the donor wafer, expanding the array distance, and properly placing and fixing them on the target substrate (such as the display backplane), at the speed of the existing mainstream LED die bonding. , It often takes dozens of days to mount a TV screen, which is far from meeting the requirements of industrialization. Therefore, it is urgent to propose new methods to improve the grasping speed and grasping accuracy, expand the distance of the chip array, and place the chips accurately. , to accelerate the pace of industrialization of Micro-LED display technology.

For the process of precisely stripping and transferring the wafer from the donor wafer, the current mainstream solutions include: 1. Laser lift-off technology. The processed Micro-LED chip is adhered on the laser-transparent transfer substrate with photosensitive glue, and the laser is applied to irradiate the chip at a specific position. The photosensitive glue absorbs the laser energy, the glue loses its viscosity, and the chip falls to the target substrate under the action of gravity. in the corresponding position. This method adopts a scheme of laser irradiation, which can selectively peel off two wafers within a specified distance, and realizes the purpose of expanding the distance of the chip array while peeling off. However, this solution requires that the transfer substrate must be a laser-transparent material, and the transfer substrate after a laser lift-off is often damaged and cannot be reused. Second, laser heating release technology. Between the laser-transparent transfer substrate and the processed Micro-LED wafer, there is an elastic layer; when the laser beam irradiates the elastic layer through the laser-transparent transfer substrate, the film protrudes through the laser thermal effect, and the Micro-LED wafer Lift up and make it leave the transfer substrate; the Micro-LED chip falls on the corresponding position of the target substrate under the action of gravity. This solution reduces the possible adverse effects of the photosensitive glue on the Micro-LED chip. However, since this solution utilizes the thermal effect of the laser, it cannot avoid adverse thermal effects on the chip.

Therefore, it is urgent to propose a new method that can release the Micro-LED chips on both laser transparent and opaque transfer substrates, avoid damage to the transfer substrate, realize the reuse of the transfer substrate, and overcome the laser thermal effect. Adverse effects of Micro-LED.

Contents of the invention

In view of the above defects, the purpose of the present invention is to propose a Micro-LED mass transfer method, which can realize the effective release of Micro-LED wafers on laser transparent and non-transparent transfer substrates, and avoid conventional laser stripping/laser heating stripping, etc. The method has adverse thermal effects on the Micro-LED wafer and the Micro-LED transfer substrate, and meanwhile the Micro-LED transfer substrate can be reused.

For reaching this purpose, the present invention adopts following technical scheme:

An ultrasonic release type Micro-LED mass transfer method, comprising the following steps,

A. Transfer preparation. The transfer substrate is placed horizontally. The lower surface of the transfer substrate is rich in elastic film. Ultrasonic transducers are installed on the surface of the generating unit;

B. Select alignment, the ultrasonic generating unit is aligned with a certain Micro-LED chip on the transfer substrate, and the direct contact is realized through the ultrasonic transducer;

C. Deformation release. When the ultrasound acts on certain specific positions, the elastic film there will be deformed and arched on the back of the Micro-LED chip, so that the chip is separated from the transfer substrate and falls onto the target substrate under the action of gravity;

D. Continuous release. After releasing a certain Micro-LED chip on the transfer substrate, the ultrasonic generating unit moves to the next release position, aligns with the Micro-LED chip at this position, and releases the Micro-LED chip at this position.

Wherein, the transfer substrate is a laser transparent or non-transparent substrate, and the transfer substrate is a rigid substrate.

In addition, in the step A, the power of the ultrasonic generating unit is 0.1-20W.

In addition, in the step A, the geometric size of the ultrasonic generating unit is smaller than the geometric size of the Micro-LED chip.

In addition, in the step A, the distance between the ultrasonic transducers on the ultrasonic generating unit is much larger than the distance between the Micro-LED chips on the transfer substrate, and the former is a positive integer multiple of the latter;

The distance between the ultrasonic transducers on the ultrasonic generating unit can be changed by moving the mechanical structure;

The distance between the ultrasonic transducers on the ultrasonic generating unit is equal to the distance between the mounting positions of the Micro-LED chip on the target substrate.

In addition, in the step A, the number of ultrasonic generating units acting simultaneously on the same transfer substrate is equal to or greater than one.

As a supplement to the above technique, in the step A, the geometric size of the wafer on the transfer substrate is 1-10 μm.

As a supplement to the above technique, in the step A, the thickness of the transfer substrate should be less than or equal to 5 mm.

Beneficial effects of the present invention: 1. In this solution, the elastic film is deformed by ultrasonic wave, so that the elastic film is deformed, and finally the Micro-LED chip pasted on the elastic film is dropped. In this technical solution, there will be no The use of lasers, liquids, and high-temperature environments has no effect on the wafer, and the elastic film will return to its original shape after the ultrasonic generating unit stops, and can be reused; 2. Since this solution uses sound waves to pass through the substrate, the substrate must be hard. , to ensure that the sound wave can be fully transmitted to the elastic membrane, thereby making the elastic membrane have sufficient deformation.

Description of drawings

FIG. 1 is a flow chart of a Micro-LED mass transfer method according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a Micro-LED mass transfer method according to an embodiment of the present invention;

Among them: 1. Ultrasonic transducer 1; 2. Ultrasonic wave; 3. Elastic film; 4. Micro-LED chip; 5. Ultrasonic generating unit; 6. Transfer substrate; 7. Target substrate.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

As shown in Figure 1-2, an ultrasonic release type Micro-LED mass transfer method includes the following steps,

A. Transfer preparation, the transfer substrate 6 is placed horizontally, the lower surface of the transfer substrate 6 is attached with an elastic film 3, the Micro-LED chip 4 is adhered to the surface of the elastic film 3, and the upper surface of the transfer substrate 6 is placed horizontally. An ultrasonic generating unit 5, on which an ultrasonic transducer 1 is installed on the surface of the ultrasonic generating unit 5;

B. Alignment is selected, the ultrasonic generating unit 5 is aligned with a Micro-LED chip 4 somewhere on the transfer substrate 6, and direct contact is realized through the ultrasonic transducer 1;

C. Deformation is released. When the ultrasound acts on certain specific positions, the elastic film 3 there will be deformed and arched on the back of the Micro-LED chip 4, so that the chip is separated from the transfer substrate 6 and falls onto the target substrate 7 under the action of gravity. ;

D. Continuous release. After releasing the Micro-LED chip 4 somewhere on the transfer substrate 6, the ultrasonic generating unit 5 moves to the next release position, aligns with the Micro-LED chip 4 on this position, and releases the Micro-LED chip 4 there.

The mass transfer method of this program adopts the combination of sound waves.

This solution is to cause the deformation of the elastic membrane 3 through ultrasonic waves, so that the elastic membrane 3 is deformed, and finally the Micro-LED chip pasted on the elastic membrane 3 is dropped. In this technical solution, no laser or liquid is used in the whole process. And the high temperature environment has no influence on the wafer, and the elastic film 3 will return to its original state after the ultrasonic generating unit 5 stops, and can be reused.

Preferably, the transfer substrate 6 is a laser transparent or non-transparent substrate, and the transfer substrate 6 is a rigid substrate.

Since the present solution uses sound waves to pass through the substrate, if the substrate is hard, it is ensured that the sound waves can be fully transmitted to the elastic membrane, so that the elastic membrane 3 has sufficient deformation.

Preferably, in the step A, the power of the ultrasonic generating unit 5 is 0.1-20W.

Further, in the step A, the geometric size of the ultrasonic generating unit 5 is smaller than the geometric size of the Micro-LED chip.

The geometric size of the ultrasonic generating unit 5 is smaller than the geometric size of the Micro-LED chip, so that one chip falls off at a time, which ensures the transfer accuracy of the chip and prevents multiple chips from falling off at a time.

Further, in the step A, the distance between the ultrasonic transducers 1 on the ultrasonic generating unit 5 is much larger than the distance between the Micro-LED wafers on the transfer substrate 6, and the former is a positive integer multiple of the latter;

The distance between the ultrasonic transducer 1 on the ultrasonic generating unit 5 can be changed by moving the mechanical structure;

The distance between the ultrasonic transducers 1 on the ultrasonic generating unit 5 is equal to the distance between the installation positions of the Micro-LED chip on the target substrate 7 .

This solution belongs to the extended solution, that is, the array of ultrasonic transducers is set, and multiple chips are transferred at one time, and there is a suitable distance, which will not affect the precision of falling off.

Preferably, in the step A, the number of ultrasonic generating units 5 acting simultaneously on the same transfer substrate 6 is equal to or greater than one.

There are multiple ultrasonic generating units 5, which can improve the efficiency of detachment.

Further, in the step A, the geometric size of the wafer on the transfer substrate 6 is 1-10 μm.

The size adaptation range in this solution can ensure that the current wafers can use the method.

Further, in the step A, the thickness of the transfer substrate 6 should be less than or equal to 5mm.

If the transfer substrate 6 is too thick, the working effect of the ultrasonic generating unit 5 will be affected, so the thickness should be less than or equal to 5 mm.

The above describes the technical principles of the present invention in conjunction with specific embodiments. These descriptions are only for explaining the principles of the present invention, and cannot be construed as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can think of other specific implementation modes of the present invention without creative efforts, and these modes will all fall within the protection scope of the present invention.

Claims (4)

1. a kind of ultrasound release type Micro-LED flood tide transfer method, which is characterized in that include the following steps,

A, transfer prepares, and transfer base substrate is horizontal positioned, the lower surface high resilience film of transfer base substrate, the adherency of Micro-LED chip On the surface of elastic membrane, it is equipped with supersonic generation unit in the position for the upper surface for laying flat transfer base substrate, in the supersonic generation unit Surface is equipped with ultrasonic transducer；

B, somewhere Micro-LED wafer alignment on selection alignment, supersonic generation unit and transfer base substrate passes through ultrasonic transducer reality Now directly contact；

C, deformation discharges, and in certain specific positions, the elastic membrane at this is deformed for ultrasonication, in Micro-LED chip The back side is arched upward, and so that chip is detached from transfer base substrate, is fallen in target substrate under the effect of gravity；

D, sustained release, after discharging transfer base substrate somewhere Micro-LED chip, supersonic generation unit is moved to next release position It sets, the Micro-LED wafer alignment in this position discharges Micro-LED chip at this；

The transfer base substrate is laser-light transparent or nontransparent substrate, and the transfer base substrate is rigid substrates；

In the step A, the power of supersonic generation unit is 0.1 ~ 20 W；

In the step A, ultrasonic transducer makes chip fall off one every time, ensure that the transfer precision of chip, avoids chip one It is secondary fall off it is multiple；

In the step A, the spacing of ultrasonic transducer is much larger than Micro-LED chip on transfer base substrate on supersonic generation unit Spacing, the former is the positive integer times of the latter；

Ultrasonic transducer can realize that spacing changes by the way that mechanical structure is mobile on supersonic generation unit；

On supersonic generation unit in the spacing with target substrate of ultrasonic transducer Micro-LED chip installation site spacing phase Deng.

2. ultrasound release type Micro-LED flood tide transfer method according to claim 1, which is characterized in that the step A In, the quantity of the supersonic generation unit of effect is equal to or more than 1 simultaneously on same transfer base substrate.

3. ultrasound release type Micro-LED flood tide transfer method according to claim 1, which is characterized in that the step A In, the geometric dimension of chip is 1 ~ 10 μm on transfer base substrate.

4. ultrasound release type Micro-LED flood tide transfer method according to claim 1, which is characterized in that the step A In, the thickness of transfer base substrate should be less than or be equal to 5mm.