WO2024031819A1

WO2024031819A1 - Test method for integrated micro led

Info

Publication number: WO2024031819A1
Application number: PCT/CN2022/124291
Authority: WO
Inventors: 张帆; 吴永胜; 张力强
Original assignee: 福建兆元光电有限公司
Priority date: 2022-08-12
Filing date: 2022-10-10
Publication date: 2024-02-15
Also published as: CN115356560A; CN115356560B

Abstract

A test method for an integrated Micro LED. By immersing a Micro LED in a conductive liquid (2) for testing, a P electrode (5) is grounded by means of the conductive liquid (2), and a common N electrode (4) which is not immersed in the conductive liquid (2) is connected to a voltage input end, so that full-angle and full-contact electrification of all sub-pixels can be realized. Compared with probe contact tests in the prior art, the test method can turn on a whole surface in a current driving mode, probes are not needed, chips would not be damaged, electrodes of each pixel would not be affected, and no subsequent soldering anomaly caused by scratches or crushes would occur; and compared with photoluminescence tests in the prior art, the test method provides an electrical parameter test module (7) between a negative voltage and a grounding end, so that electrical parameter tests can be performed repeatedly for multiple times, thereby improving the efficiency and accuracy of measuring integrated Micro LEDs.

Description

A testing method for integrated Micro LED

Technical field

The invention relates to the field of semiconductor electronic technology, and in particular to a testing method for integrated Micro LED.

Background technique

IntegratedMicro LEDs are generally composed of a large number of sub-pixels, with the number of pixels ranging from 500,000 to millions. At the same time, the electrode size is extremely small between 1 and 8 μm. It cannot be tested by the current common probe testing method. The stimulation method cannot detect some important electrical parameters. Therefore, highly integrated and small-sized Micro LED testing, especially power-on testing, is an unsolved problem in the entire industry.

There are two main types of existing tests: one is the probe contact test, but for Micro LED, the electrodes are small, the probes cannot effectively contact, and there are too many sub-pixels, and the efficiency of the one-by-one test is extremely low; the other One is the photoluminescence test, which can detect basic optical parameters, but cannot detect important electrical parameters such as leakage, forward voltage, and starting voltage.

technical problem

The technical problem to be solved by the present invention is to provide an integrated Micro LED testing method that can test the electrical parameters of the entire integrated Micro LED and improve the detection efficiency and accuracy of the integrated Micro LED.

Technical solutions

In order to solve the above technical problems, the technical solution adopted by the present invention is:

An integrated Micro LED testing method, including steps:

Adding a conductive liquid to a light-transmissible container, the conductive liquid being grounded;

Integrated Micro The pixel area of the LED is immersed in the conductive liquid, and each pixel in the pixel area corresponds to a P electrode one-to-one;

Connect the common N electrode of the integrated Micro LED that is not immersed in the conductive liquid to the voltage input end of the electrical parameter testing module;

The electrical parameter testing module is used to perform electrical parameter testing between the voltage input terminal and the ground terminal of the conductive liquid.

beneficial effects

The beneficial effect of the present invention is that by immersing the Micro LED in the conductive liquid for testing, the P electrode is grounded through the conductive liquid, and the common N electrode that is not immersed in the conductive liquid is connected to the voltage input terminal, so that all sub-pixels can be fully contacted at all angles. The ground is electrified. Compared with the probe contact test in the prior art, the present invention can use current driving to achieve full-surface lighting without the need for probes, without damaging the chip itself, without affecting the electrodes of each pixel, and without Due to scratches and crushing, subsequent welding abnormalities are caused; compared with the photoluminescence test in the prior art, an electrical parameter testing module is set up between the negative voltage and the ground terminal, and the electrical parameters can be tested repeatedly. testing to improve the detection efficiency and accuracy of integrated Micro LEDs.

Description of drawings

Figure 1 is a flow chart of an integrated Micro LED testing method according to an embodiment of the present invention;

Figure 2 is a schematic diagram of a liquid phase method for testing an integrated Micro LED according to an embodiment of the present invention;

Figure 3 is a schematic diagram of light collection of an integrated Micro LED testing method according to an embodiment of the present invention;

Label description:

1. Translucent container; 2. Conductive liquid; 3. Liquid level line; 4. Common N pole; 5. P electrode; 6. Light collecting device; 7. Electrical parameter test module.

Embodiments of the invention

In order to describe the technical content, achieved objectives and effects of the present invention in detail, the following description will be made in conjunction with the embodiments and the accompanying drawings.

Referring to Figure 1, an embodiment of the present invention provides an integrated Micro LED testing method, including the steps:

As can be seen from the above description, the beneficial effects of the present invention are: by immersing the Micro LED in the conductive liquid for testing, the P electrode is grounded through the conductive liquid, and the common N electrode that is not immersed in the conductive liquid is connected to the voltage input terminal, which enables all sub-pixels to be tested. Electrification from all angles and full contact. Compared with the probe contact test in the prior art, the present invention can use current driving to achieve full-surface lighting without the need for probes, without damaging the chip itself, without affecting the electrodes of each pixel, and without Due to scratches and crushing, subsequent welding abnormalities are caused; compared with the photoluminescence test in the prior art, an electrical parameter testing module is set up between the negative voltage and the ground terminal, and the electrical parameters can be tested repeatedly. testing to improve the detection efficiency and accuracy of integrated Micro LEDs.

Furthermore, it also includes:

The optical parameters after the pixel area is lit are obtained through a light collecting device outside the light-transmissive container.

It can be seen from the above description that by utilizing the light transmittance of the light-transmissible container, the optical parameters of all pixels can be tested at one time outside the container wall using a light-collecting device.

Further, before immersing the pixel area of the integrated Micro LED into the conductive liquid, the process includes:

In the integrated Micro A liquid level buffer is set between the common N electrode of the LED and the pixel area;

In the integrated Micro The area in the LED except the common N electrode and the pixel area is covered with an insulating layer.

As can be seen from the above description, a liquid level buffer is reserved between the common N electrode and the pixel area to facilitate the separation of the common N electrode and the pixel area; the short circuit problem of the chip in the liquid phase is solved by covering the surface with insulating material.

Further, the immersing the pixel area of the integrated Micro LED into the conductive liquid also includes:

Adjust the integrated Micro The position of the LED is such that the conductive liquid level is within the range of the liquid level buffer zone.

It can be seen from the above description that when the chip is immersed in the conductive liquid, it is easy to control the immersed pixel area without affecting the common N electrode.

Further, connecting the common N electrode of the integrated Micro LED that is not immersed in the conductive liquid to the voltage input end of the electrical parameter testing module includes:

Use a conductive clamp to clamp the common N pole of the integrated Micro LED, and connect the conductive clamp to the voltage input end of the electrical parameter testing module.

As can be seen from the above description, the voltage input terminal is used to contact the common N-pole metal of the integrated Micro LED through a conductive clamp, and simultaneously functions to input N-pole electrons and fix the chip.

Further, the light-transmissive container is a container with at least one side being transparent.

Further, the material of the light-transmissive container includes silicon oxide or aluminum oxide.

It can be seen from the above description that the light-transmissive container is made of a stable material with good light transmittance, so that the light-transparent container has good light transmittance.

Further, the conductive liquid includes a suspension of carbon nanotubes or nanometal particles.

It can be seen from the above description that using a suspension of carbon nanotubes or nanometal particles as a conductive liquid can ensure good light transmittance while ensuring conductive performance.

Further, the conductive liquid grounding includes:

Insert a grounding wire into the conductive liquid.

Further, the conductive liquid grounding also includes:

A conductive part is provided in the light-transmissible container, and the conductive part is grounded.

As can be seen from the above description, the conductive liquid can be grounded through a wire or through a conductive part in a light-transmissive container, which can be applied to different scenarios.

The above-mentioned testing method of integrated Micro LED of the present invention is suitable for integrated Micro LEDs with a common N-pole. The one-time photoelectric performance test of LED chips is explained below through specific implementation methods:

Embodiment 1

Please refer to Figure 1 to Figure 3, a test method for integrated Micro LED, including steps:

S1. Add conductive liquid 2 into the light-transmissive container 1, and the conductive liquid 2 is grounded.

Specifically, a light-transparent container 1 is used to hold the conductive liquid 2, wherein the light-transparent container 1 is non-conductive and has a size of 1*1*1~50*50*50cm;

The light-transmissive container is a container with at least one side being transparent, and its material can be silicon oxide, quartz, alumina and other stable materials with good light transmittance; the conductive liquid 2 can be carbon nanotubes or nanometal particle suspensions.

In this embodiment, a grounding wire is inserted into the conductive liquid to achieve grounding of the conductive liquid.

In other embodiments, a conductive part may be provided in the light-transmissive container, and the conductive part may be grounded to achieve grounding of the conductive liquid.

S2. Immerse the pixel area of the integrated Micro LED into the conductive liquid 2. Each pixel in the pixel area corresponds to a P electrode 5 one-to-one.

Among them, in the integrated Micro A liquid level buffer is provided between the common N-pole 4 of the LED and the pixel area. In the integrated Micro LED, the area except the common N-pole 4 and the pixel area is covered with an insulating layer.

For details, please refer to Figure 2, integrated Micro In the pixel area of the LED chip, each sub-pixel has a P electrode 5, which is covered by an insulator except for the electrode. In this embodiment, the conductive nature of the N-type gallium nitride material itself is used to realize the common N electrode, and the common N electrode 4 The N-type connection between the electrode and the pixel area is also covered by an insulator, and a distance of at least 1 mm is reserved between the common N electrode 4 and the pixel area as a liquid level buffer area.

Integrated Micro The pixel area of the LED is immersed in the liquid, and the liquid level line 3 stays within the liquid level buffer area of the micro LED.

S3. The integrated Micro that is not immersed in the conductive liquid 2 The common N pole 4 of the LED is connected to the voltage input end of the electrical parameter testing module 7 .

Specifically, in this embodiment, the voltage input terminal of the electrical parameter test module 7 is a negative voltage. The conductive clip is connected to the voltage input terminal of the electrical parameter test module, and the common N of the integrated Micro LED is connected through the conductive clip. The metals of pole 4 are in contact, and a negative voltage is applied to the common N pole 4; among them, the width of the metal of the common N pole 4 is generally 1mm, and can be clamped in conventional sizes.

At this point, the negative voltage is responsible for providing electrons. The electrons are introduced from the common N electrode 4 of the Micro LED to the NP junction of the chip, and then from the P electrode 5 to the conductive liquid 2. The conductive liquid 2 is grounded, and the electrons are exported from the conductive liquid 2 to the ground terminal, completing the entire process. circuit path. During the test process, no solid body came into contact with the P electrode 5 of each pixel before, during and after powering on, which did not damage the chip itself or affect the electrode of each pixel.

S4. Conduct electrical parameter testing through the electrical parameter testing module between the voltage input terminal and the ground terminal of the conductive liquid.

Specifically, the electrical parameters can be measured using the electrical parameter test module 7 between the voltage input terminal (N connection) and the ground terminal (P connection). Therefore, this embodiment can measure the chip, and according to the measured overall electrical parameters The numerical value can be used to determine whether there are pixels with leakage or electrical abnormalities.

The electrical parameter testing module 7 includes an ammeter and a voltmeter.

S5. Obtain the optical parameters after the pixel area is lit through the light collecting device 6 outside the light-transmissive container 1 .

Among them, please refer to Figure 3. The light-collecting device 6 is 11~100mm away from the light-transmitting container. During the test, you can choose the electrode of the integrated MicroLED chip to face the light-collecting device 6, or you can choose the substrate of the chip, that is, the backside opposite to the electrode. , facing the light collecting device 6.

The light collecting device 6 is placed outside the container, and the brightness and wavelength parameters of all pixels are collected after the pixel area is lit; therefore, whether the chip is qualified can be determined based on the electrical parameters and the brightness and wavelength parameters of the pixels, that is, the verification is completed. Micro LED is powered on and all pixels are lit up at the same time.

Among them, the light-collecting device 6 can measure the optical parameters of the entire chip, or the light-collecting device 6 can be moved to measure the local optical parameters of the chip.

Therefore, in this embodiment, there is no need to use a special drive circuit and drive chip. Instead, a transparent liquid conductive material is used to contact the P electrode 5. Taking advantage of the large size of the common N electrode 4, direct physical contact is conducted, thereby electrically exciting the At the same time, all pixels are illuminated through contact power; and the integrated Micro The surface insulation capability of the LED itself prevents short circuit between the liquid P electrode 5 and the common N electrode 4, ensuring the feasibility of the detection method in this embodiment. An electrical parameter test module is set between the negative voltage and the ground terminal, and an electrical parameter test module is set between the negative voltage and the ground terminal, enabling simultaneous photoelectric testing and improving the detection efficiency and performance of integrated Micro LEDs. accuracy.

In summary, the present invention provides an integrated Micro LED testing method that uses a liquid conductive substance to contact the P electrode of the Micro LED, thereby achieving gapless contact and massive simultaneous contact testing. During testing, the electrode orientation can be selected. For the light collector, you can also choose the substrate of the chip, that is, the backside opposite to the electrode, facing the light collector, and use the insulation layer between the P surface and the PN electrode to ensure that no short circuit occurs during testing. Use a light collector to measure the light parameters of all array pixels at the same time, and judge whether each pixel is qualified based on the light parameter results. Taking advantage of the larger size of the common N electrode, the N electrode is directly clamped using an external clamp. Connect the liquid P electrode contact material to the ground, and connect the common N terminal of the solid clamp to a negative voltage to realize the conduction of the LED. At the same time, the electrical parameters when lighting can be obtained by testing the PN power supply terminal. Compared with the probe contact test in the prior art, the present invention can use current driving to achieve full-surface lighting without the need for probes, without damaging the chip itself, without affecting the electrodes of each pixel, and without Due to scratches and crushing, subsequent welding abnormalities are caused; compared with the photoluminescence test in the prior art, an electrical parameter testing module is set up between the negative voltage and the ground terminal, and the electrical parameters can be tested repeatedly. testing to improve the detection efficiency and accuracy of integrated Micro LEDs.

The above are only embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent transformations made using the contents of the description and drawings of the present invention, or directly or indirectly applied in related technical fields, are equally included in within the scope of patent protection of this invention.

Claims

A testing method for integrated Micro LED, which is characterized by including steps:

Adding a conductive liquid to a light-transmissible container, the conductive liquid being grounded;

Immerse the pixel area of the integrated Micro LED into the conductive liquid, and each pixel in the pixel area corresponds to a P electrode one-to-one;

Connect the common N electrode of the integrated Micro LED that is not immersed in the conductive liquid to the voltage input end of the electrical parameter testing module;

The electrical parameter testing module is used to perform electrical parameter testing between the voltage input terminal and the ground terminal of the conductive liquid.
An integrated Micro according to claim 1 The LED testing method is characterized by also including:

The optical parameters after the pixel area is lit are obtained through a light collecting device outside the light-transmissive container.
An integrated Micro according to claim 1 The LED testing method is characterized in that before immersing the pixel area of the integrated Micro LED into the conductive liquid, the method includes:

A liquid level buffer is provided between the common N electrode and the pixel area of the integrated Micro LED;

In the integrated Micro LED, the area except the common N electrode and the pixel area is covered with an insulating layer.
An integrated Micro according to claim 3 The LED testing method is characterized in that immersing the pixel area of the integrated Micro LED into the conductive liquid further includes:

Adjust the position of the integrated Micro LED so that the liquid level of the conductive liquid is within the range of the liquid level buffer zone.
The testing method of integrated Micro LED according to claim 1, characterized in that the common N-pole of the integrated Micro LED that is not immersed in the conductive liquid and the voltage input end of the electrical parameter testing module are Connections include:

Use a conductive clamp to clamp the common N pole of the integrated Micro LED, and connect the conductive clamp to the voltage input end of the electrical parameter testing module.
An integrated Micro LED testing method according to any one of claims 1 to 5, characterized in that the light-transmissive container is a container with at least one side being transparent.
An integrated Micro according to claim 6 The LED testing method is characterized in that the material of the light-transmissive container includes silicon oxide or aluminum oxide.
The testing method of integrated Micro LED according to any one of claims 1 to 5, characterized in that the conductive liquid includes a suspension of carbon nanotubes or nanometal particles.
An integrated Micro according to claim 1 The LED testing method is characterized in that the conductive liquid grounding includes:

Insert a grounding wire into the conductive liquid.
An integrated Micro according to claim 1 The LED testing method is characterized in that the conductive liquid grounding also includes:

A conductive part is provided in the light-transmissible container, and the conductive part is grounded.