Electrical detection method of LED chip

Abstract

The invention relates to an electrical property detection device and an electrical property detection method. The electrical detection device comprises a substrate and a jig part. The substrate is used for bearing a large amount of transferred target objects. The electrical detection device is used for performing electrical detection on the target object. The jig part is arranged opposite to the substrate. The jig part comprises a light-permeable upper electrode jig. In the electrical detection period, the upper electrode jig is connected with a plurality of target objects, and the substrate serves as a lower electrode of the plurality of target objects. The upper electrode jig and the lower electrode generate a voltage difference after being electrified so as to drive the target object to emit light. After the light beam is transmitted through the jig part, the electrical detection device carries out electrical detection on the target object.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a method for detecting electrical properties of LED chips. Background Art

[0002] The size of LEDs varies depending on their application. Large-sized LEDs can be used in lighting or disinfection (such as UV LEDs), while small-sized LEDs (such as mini-LEDs or micro-LEDs) can be used in display backlight modules or directly used as pixels in display panels (such as self-luminous display panels such as OLEDs).

[0003] For small LED chips, especially micro-LEDs, the lattice matching of the materials and the differences in substrate size necessitate a micro-LED thin film transfer process after the epitaxial growth process to transfer millions of micron-sized micro-LEDs onto the display substrate. This process of transferring micro-LEDs onto the display substrate is known as mass transfer technology. Within the field of mass transfer technology, if the transfer process cannot be completed efficiently and within a reasonable timeframe, mass production is impossible.

[0004] Furthermore, because the number of chips involved in mass transfer is orders of magnitude greater than in traditional applications, defective products generated during the mass transfer and placement process are a key concern, necessitating electrical testing of these defective products. However, in the current micro-LED device manufacturing process, electrical testing requires access to the circuitry connecting the components, and therefore is typically performed only in the final stages before shipment. Summary of the Invention

[0005] The purpose of this application is to provide an electrical property detection method for LED chips, which can effectively detect the electrical properties of vertical MicroLED chips after mass transfer.

[0006] An embodiment of the present application proposes an electrical detection device, which includes a substrate and a fixture part. The substrate is used to carry multiple targets after mass transfer. The electrical detection device is used to perform electrical detection on the targets. The fixture part is arranged relative to the substrate. The fixture part includes a light-transmitting upper electrode fixture. During the electrical detection, the upper electrode fixture is connected to multiple targets, and the substrate serves as the lower electrode of the multiple targets. When the upper electrode fixture and the lower electrode are energized, a voltage difference is generated to drive the target to emit light. After the light beam passes through the fixture part, the electrical detection device performs electrical detection on the target.

[0007] In some embodiments of the present application, the fixture portion further includes a transparent substrate, and the upper electrode fixture is disposed on the transparent substrate.

[0008] In some embodiments of the present application, the upper electrode fixture is disposed corresponding to the light-emitting layers of the multiple targets.

[0009] In some embodiments of the present application, the multiple targets are vertical Micro LED chips.

[0010] In some embodiments of the present application, the electrical testing device further includes a testing unit, a power supply unit, and a control unit. The testing unit is disposed relative to the substrate and the fixture unit so that the testing range covers at least a portion of the substrate and the fixture unit. The testing unit is configured to capture images of the substrate and the fixture unit. The power supply unit is configured to supply voltage and current to the upper electrode fixture and the substrate during electrical testing. The control unit is coupled to the substrate, the fixture unit, the testing unit, and the power supply unit. The control unit is configured to control the operation of the testing unit and the power supply unit.

[0011] The present invention provides an electrical testing method for LED chips, suitable for use with an electrical testing device including a fixture. The method includes: performing position detection on an LED chip placed on a substrate after mass transfer to obtain position information; adjusting the upper electrode fixture of the fixture to the corresponding position of the LED chip based on the position information; supplying voltage and current to the LED chip to perform a lighting test; capturing images of the substrate and fixture during the lighting test; and analyzing the captured test data to determine whether the LED chip is lit. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of an electrical detection device according to an embodiment of the present application;

[0013] Figure 2A A schematic top view of a fixture portion according to an embodiment of the present application;

[0014] Figure 2B A schematic cross-sectional view of a fixture portion according to an embodiment of the present application;

[0015] Figure 3 A schematic diagram of the structure of a vertical Micro LED chip after mass transfer according to an embodiment of the present application; and

[0016] Figure 4 This is a flowchart of the steps of the electrical detection method according to an embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to make the above-mentioned objectives, features and advantages of the present technical solution more clearly understood, the specific embodiments of the proposed technical solution are described in detail below with reference to the accompanying drawings. The following descriptions of the various embodiments of the technical solution of the present invention are for illustration only and are not intended to be all embodiments of the present invention or to limit the present invention to specific embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this disclosure.

[0018] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may also be an element centered thereon. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an element centered thereon at the same time. The terms "vertical", "horizontal", "left", "right", "up", "down" and similar expressions used herein are merely intended to indicate relative positional relationships based on the accompanying drawings, and do not limit the elements using the terms to being implemented only in a representative manner. When the absolute position of the object being described changes, the description of the relative position may also change accordingly.

[0019] The descriptions of "substantially", "substantially", "approximately", etc. in this document are used to recognize the error range implied by possible unintended effects and deviations in the process or material selection. The error range may include a range of changes that do not significantly change the material structure, configuration, characteristics, or effect, such as a range of 0%-10% deviation, where the error range is clear to those skilled in the art. For example, when describing "two objects being substantially parallel", if it is actually observed that there is a slight height difference between the two objects, but this height difference is negligible (e.g., less than 10%) relative to the size of the objects themselves and does not affect the effect, then the relative configuration of the two objects observed will still be interpreted as being within the range of "substantially parallel" described herein.

[0020] All descriptions of specific values ​​in this disclosure, even if not explicitly stated, include the meaning of "approximately" or "substantially." This means that these specific values ​​will include a possible range of numerical errors to account for possible unintended effects and deviations in the process or material selection. This numerical error range can include changes in values ​​that do not significantly change the material structure, properties, or effects, such as a range of 0% to 10%. This error range is clear to those skilled in the art.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the relevant listed items.

[0022] Figure 1 This is a schematic diagram of an electrical detection device according to an embodiment of the present application. Figure 1 , this embodiment relates to an electrical property detection device 100, which is used to detect the electrical properties (such as current characteristics, voltage characteristics and / or lighting characteristics, etc.) of at least one target object on a substrate 110. The target object CP may be, for example, a small-sized electronic component such as an LED chip, specifically, a sub-micron light-emitting diode (Mini LED) or a micro light-emitting diode (Micro LED), but the present application is not limited to this. The electrical property detection device 100 of this embodiment is particularly suitable for performing electrical property detection on vertical Micro LED chips during the manufacturing process (especially the stage between mass transfer and mounting the Micro LED chip on the substrate). In other embodiments, the electrical property detection 100 can also be used to detect the electrical properties of other types of target objects CP besides LED chips. In one embodiment, the substrate 110 may be a target substrate for carrying the transferred target object CP.

[0023] The electrical testing device 100 of this embodiment includes a substrate 110, a fixture 120, a testing unit 130, a control unit 140, and a power supply unit 150. In this embodiment, the substrate 110 is used to support a plurality of transferred targets CP, such as vertical Micro LED chips (hereinafter referred to as LED chips). Therefore, the electrical testing device 100 can be used to test the electrical properties of a large number of transferred vertical Micro LED chips.

[0024] The fixture 120 is positioned opposite the substrate 110 and has a light-transmissive conductive structure. During electrical testing, the fixture 120, in conjunction with the substrate 110 serving as the lower electrode, applies a test voltage to generate a voltage differential between the upper and lower electrodes of the LED chip, thereby driving the LED chip.

[0025] The detection part 130 is arranged relative to the substrate 110 and the fixture part 120 so that the detection range can cover at least a portion of the substrate 110 and the fixture part 120, wherein the detection part 130 is used to capture the electrical characteristics of the substrate 110 and the fixture part 120. In some embodiments, the detection part 130 may include one or more image capture devices. During the electrical detection process, a normal LED chip will be illuminated in response to the detection voltage, so that the light beam can pass from the fixture part 120 toward the detection part 130. The detection part 130 can capture the brightness data of the LED chip as a basis for detection judgment. In other words, the electrical characteristics may be, for example, the luminous brightness of the LED chip after it is illuminated in response to the detection voltage.

[0026] In some embodiments, the image capture device may be, for example, an optical microscope, a charge coupled device (CCD) image sensor, a complementary metal oxide semiconductor (CMOS) image sensor, and a combination of one or more of these, and this application is not limited thereto.

[0027] The control unit 140 is coupled to the substrate 110, the fixture unit 120, the testing unit 130, and the power supply unit 150, and is used to control the operation of the testing unit 130 and the power supply unit 150. In some embodiments, the control unit 140 can be implemented using hardware, firmware, or software, and is not necessarily located within the electrical testing device 100. For example, the control unit 140 can be implemented using an external computer, which can transmit signals to various modules in the electrical testing device 100 via a specific transmission interface to achieve control.

[0028] In this embodiment, the fixture part 120 is connected to the power supply part 150, and the power supply part 150 supplies the input of the detection voltage and current. When the electrical detection device 100 performs electrical detection on the LED chip (such as lighting test), the fixture part 120 can be used with a conductive substrate 110 (as a lower electrode) that carries a large number of transferred LED chips. Specifically, during the lighting test, the electrical detection device 100 performs image capture through the detection part 130. The detection part 130 is set on one side of the transparent fixture part 120 (for example, the position above the figure), and the light source emitted by the LED chip after being illuminated can pass through the transparent fixture part 120 and be captured by the detection part 130. The captured detection data can be analyzed by the control part 140. For example, the control part 140 sets the grayscale value of the image within a unit area, and judges whether the LED chip is illuminated by the difference in grayscale value.

[0029] The following describes embodiments of the fixture and the structure of the vertical Micro LED chip of the present application.

[0030] Figure 2A This is a schematic top view of the fixture portion of an embodiment of the present application. Figure 2B This is a cross-sectional diagram of the fixture portion of the embodiment of the present application. Figure 2A and Figure 2B In this embodiment, the fixture portion 120 is, for example, a probe unit (PU). Structurally, the fixture unit PU comprises a contact portion (CT) and a conductive portion (CON). The contact portion (CT) has multiple protrusions (PS). The arrangement of the protrusions (PS) corresponds to the arrangement of the LED chips on the substrate (110). When the contact portion (CT) contacts the LED chip, each protrusion (PS) electrically connects to the top electrode of the corresponding LED chip. The conductive portion (CON) is disposed in the periphery of the contact portion (CT) to transmit / conduct the test voltage received from the power supply to the contact portion (CT).

[0031] From the configuration point of view, the fixture unit PU includes a transparent substrate 122 and a light-transmitting upper electrode fixture 124. The raised structure PS is located on the side of the upper electrode fixture 124 close to the LED chip, wherein the upper electrode fixture 124 can be used to electrically connect to the upper electrode of the LED chip, and the upper electrode of each LED chip and its position can be customized to the light-transmitting upper electrode fixture 124. The electrical detection device 100 can generate a voltage difference between the upper and lower electrodes by energizing the fixture part 120 and the lower electrode, thereby driving the LED chip to emit light. After the light beam passes through the top of the fixture part 120, the brightness of the LED chip after the mass transfer is detected by the detection part 130. In some embodiments, the transparent substrate 122 is, for example, a glass substrate, and the light-transmitting upper electrode fixture 124 is, for example, a high-penetration ITO conductive film, and this application is not limited to this.

[0032] Figure 3 This is a schematic diagram of the structure of the vertical Micro LED chip after mass transfer in the embodiment of the present application. Figure 3 , Figure 3A plurality of vertical Micro LED chips 20 (hereinafter referred to as LED chips 20) are shown to be disposed on a substrate 110 after mass transfer. The LED chip 20, for example, includes a light-emitting layer 21, a plurality of metal layers 22-24, and a connection layer 25. The metal layer 22 is disposed on one side of the light-emitting layer 21 (the upper side in this embodiment) and serves as the upper electrode of the LED chip 20 (hereinafter referred to as the upper electrode 22). The metal layer 23 is disposed on the other side opposite the light-emitting layer 21 and is connected to the metal layer 24 on the side away from the light-emitting layer 21 through the connection layer 25. When the LED chip 20 is placed on the substrate 110 after mass transfer, the metal layer 24 of the LED chip 20 is electrically connected to the substrate 110, so that the substrate 110 can be regarded as the lower electrode of the LED chip 20. In this embodiment, the upper electrode 22 is, for example, an N-pole and the lower electrode is, for example, a P-pole, but the present application is not limited thereto.

[0033] Since the electrodes 22 on the LED chips 20 cannot be tested for electrical conduction after mass transfer, the following electrical testing procedures must be used: Figure 2A and Figure 2B The upper electrode fixture 124 described in the embodiment is used to achieve electrical connection with the upper electrode 22 of the LED chip 20. When powered, the upper electrode fixture 124 is matched with the substrate 110 as the lower electrode to generate a voltage difference to perform electrical testing on the LED chip 20.

[0034] The electrical detection device 100 can be Figure 4 The electrical detection method operates in which Figure 4 This is a flow chart of the steps of the electrical detection method of the embodiment of the present application. Please also refer to Figure 1 and Figure 4 The electrical detection of this embodiment includes: detecting the target object CP (eg Figure 3 The LED chip 20 shown in the figure is subjected to position detection to obtain position information (step S110); the fixture part 120 is adjusted to the position of the corresponding target object CP according to the position information (step S120); the power supply part 150 is controlled to supply voltage and current to the upper and lower electrodes of the target object CP to perform an electrical test (step S130); during the electrical test, the electrical characteristics are captured by the detection part 130 (step S140); and the captured detection data is analyzed by the control part 140 to determine the operating status of the target object CP (step S150).

[0035] More specifically, the fixture unit PU shown in FIG2 is used to Figure 3Take the process of performing electrical testing on the LED chip 20 as an example. In step S110, after the LED chip 20 is placed on the substrate 110 after mass transfer, the position of the LED chip 20 can be detected to obtain position information. In step S120, the upper electrode fixture 124 of the fixture part 120 can be adjusted to the position of the corresponding LED chip 20 according to the position information, so that the various protruding structures PS on the upper electrode fixture 124 are electrically connected to the upper electrode 22 of the LED chip 20. In step S130, the conductive part CON of the fixture unit PU and the substrate 110 are powered by the power supply part 150, so that the power is applied to the upper electrode 22 of the LED chip 20 through the conductive part CON and the various protruding structures PS, and is also applied to the substrate 110 serving as the lower electrode, thereby lighting up the LED chip 20. In steps S140 and S150 , after the detection unit 130 captures an image, the control unit 140 may analyze the captured image data and determine whether the LED chip 20 is lit.

[0036] In summary, the electrical testing device of this application can be used to test the electrical properties of vertical Micro LED chips after mass transfer. Existing technologies do not yet address this issue. This application utilizes a light-transmitting upper electrode fixture, which, when powered, generates a voltage difference with the lower electrode to drive the vertical Micro LED chips to emit light. After the light beam passes through the fixture, the testing unit performs brightness testing on the vertical Micro LED chips after mass transfer.

[0037] Although the present application has been disclosed using the above-mentioned embodiments, they are not intended to limit the present application. Any person skilled in the art may make various changes and modifications to the above-mentioned embodiments without departing from the spirit and scope of the present application, and these changes and modifications still fall within the technical scope protected by the present application. Therefore, the scope of protection of the present application shall be determined by the claims.

Claims

1. An electrical detection device comprising: a substrate for carrying a plurality of target objects after mass transfer, wherein the electrical detection device is used to perform electrical detection on the plurality of target objects; and A fixture portion is arranged relative to the substrate, and the fixture portion includes a light-transmissive upper electrode fixture, During the electrical testing, the upper electrode fixture is connected to the multiple targets, and the substrate serves as the lower electrode of the multiple targets. When the upper electrode fixture and the lower electrode are energized, a voltage difference is generated to drive the multiple targets to emit light. After the light beam passes through the fixture part, the electrical testing device performs the electrical testing on the multiple targets.

2. The electrical detection device according to claim 1, wherein: The fixture part further includes a transparent substrate, and the upper electrode fixture is disposed on the transparent substrate.

3. The electrical detection device according to claim 1, wherein: The upper electrode fixture is arranged corresponding to the light-emitting layers of the multiple targets.

4. The electrical detection device according to claim 1, wherein: The multiple targets are vertical MicroLED chips.

5. The electrical property detection device according to claim 1, wherein: Also includes: a detection portion disposed relative to the substrate and the fixture portion so that a detection range covers at least a portion of the substrate and the fixture portion, wherein the detection portion is used to capture images of the substrate and the fixture portion; a power supply unit for supplying voltage and current to the upper electrode fixture and the substrate during electrical testing; as well as The control unit is coupled to the substrate, the fixture unit, the detection unit, and the power supply unit, and is used to control the operations of the detection unit and the power supply unit.

6. A method for testing the electrical properties of an LED chip, suitable for use with an electrical testing device including a fixture, the method comprising: Performing position detection on LED chips placed on a substrate after mass transfer to obtain position information; Adjusting the upper electrode fixture of the fixture part to the position of the corresponding LED chip according to the position information; Supplying voltage and current to the LED chip to perform a lighting test; During the lighting test, images of the substrate and the fixture are captured; as well as The captured detection data is analyzed to determine whether the LED chip is lit.

7. The method for detecting electrical properties of an LED chip according to claim 6, wherein: The fixture part further includes a transparent substrate, and the upper electrode fixture is disposed on the transparent substrate.

8. The method for detecting electrical properties of an LED chip according to claim 6, wherein: The upper electrode fixture is arranged corresponding to the light-emitting layer of the LED chip.

9. The method for detecting electrical properties of an LED chip according to claim 6, wherein: The LED chip is a vertical Micro LED chip.

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