Micro LED package integrated with electrostatic discharge protection device and high anti-static capability implementation method thereof

Abstract

The application discloses a MicroLED package integrated with an electrostatic discharge protection device and a high anti-static capability implementation method thereof, comprising a packaging substrate and one or more MicroLED chips arranged on the packaging substrate, and each MicroLED chip is electrically connected with an independent Zener diode, the Zener diode is connected in parallel with the corresponding MicroLED chip, and is integrated and packaged in the same packaging body, used for providing electrostatic discharge protection for the MicroLED chip, in the packaging process of the MicroLED chip, a preselected Zener diode is accurately electrically connected with each MicroLED chip, then overall packaging is carried out, and finally a MicroLED package with significantly enhanced anti-static capability is formed. The application aims to overcome the significant deficiencies of the existing MicroLED package in the anti-static capability and the inherent limitations of the traditional ESD protection strategy, thereby significantly improving the ESD pressure upper limit of the MicroLED package, and greatly improving the yield and reliability of the MicroLED package in the manufacturing and terminal use processes.

Description

Technical Field

[0001] This invention relates to the field of semiconductor display technology, specifically to a MicroLED package with integrated electrostatic discharge protection devices and a method for achieving high antistatic capability. Background Technology

[0002] MicroLED, as a revolutionary next-generation display technology, is considered a strong contender to replace LCD and OLED due to its superior performance in pixel size, brightness, contrast, response speed, color saturation, energy efficiency, and reliability. It has shown unprecedented potential in a wide range of applications, from AR / VR microdisplays and wearable devices to ultra-large high-definition displays.

[0003] However, achieving extreme miniaturization of MicroLED chips is one of the core technological challenges they face. Currently, the size of commercially available or R&D-developed MicroLED chips has generally shrunk to below 10 micrometers (μm), and even to the level of several micrometers. This unprecedented size reduction, while bringing ultra-high pixel density and visual effects, has also greatly weakened the physical structural strength and electrical stability of the chip itself, making it exceptionally vulnerable to electrostatic discharge (ESD) events. Typically, the ESD withstand voltage (such as human body mode HBM) of a single MicroLED chip is generally much lower than that of traditional semiconductor devices, even as low as below 500V. This inherently low ESD withstand voltage characteristic makes MicroLED chips highly susceptible to the unavoidable accumulation and release of static electricity in the environment throughout the entire industry chain, especially in chip transfer, packaging (such as die attach, wire bonding, molding), and subsequent surface mount technology (SMT) processes. Even a tiny ESD event, invisible to the naked eye, can cause local breakdown, leakage, decreased luminous efficiency, or even permanent failure (dead LED) of the sensitive PN junction inside the MicroLED chip. The damage caused by these ESDs is the main reason for the low yield rate of MicroLED product manufacturing processes and the poor reliability of end products.

[0004] To address the inherent ESD vulnerability of MicroLED chips, existing technologies mainly employ the following two conventional strategies, but both have significant limitations: (1) Post-packaged screening strategy: Comprehensive ESD testing (such as HBM, MM, etc.) is conducted before or after the MicroLED chip is packaged. Through this test, "robust" products with relatively good ESD performance indicators are screened out for downstream applications. However, this strategy is passive and lagging in nature. It does not fundamentally improve the inherent ESD tolerance limit of the chip or package, but merely eliminates unqualified products. This not only introduces additional high testing costs and prolongs the production cycle, but more importantly, it directly leads to a loss of yield of chips and packages. Moreover, the ESD withstand voltage peak of the screened "qualified products" is still at a relatively low level, which cannot meet the more stringent anti-static protection requirements in the future.

[0005] (2) Size Compromise Strategy: Where possible, try using relatively large MicroLED chips. Theoretically, the larger the chip size, the slightly improved its ESD tolerance. However, this strategy runs counter to the core development direction of MicroLED technology, which pursues extreme miniaturization to achieve high pixel density and high PPI (pixels per inch). Using larger chips will limit the improvement of display resolution, increase the cost per chip, and its effect on improving the ESD limit is extremely limited, far from meeting the needs of actual production and application.

[0006] In summary, existing ESD protection strategies only address the symptoms, not the root cause, and cannot effectively solve the ESD damage problem in MicroLED products during production and use. Therefore, there is an urgent need for an innovative technology that, starting from the MicroLED packaging design level, can proactively, effectively, and fundamentally improve the upper limit of the package's anti-static capability, thereby significantly improving the yield and long-term reliability of MicroLEDs. Summary of the Invention

[0007] The purpose of this invention is to provide a MicroLED package that achieves active, integrated electrostatic discharge protection at the packaging level and a method for achieving high antistatic capability, so as to solve the problems of significant deficiencies in the antistatic capability of existing MicroLED packages and the inherent limitations of traditional ESD protection strategies.

[0008] To achieve the above objectives, a MicroLED package integrating electrostatic discharge protection devices is provided, comprising a package substrate and one or more MicroLED chips disposed on the package substrate, wherein each MicroLED chip is electrically connected to an independent Zener diode, the Zener diode is connected in parallel with the corresponding MicroLED chip, and is integrated into the same package to provide electrostatic discharge protection for the MicroLED chip.

[0009] Preferably, the Zener diode has a preset reverse breakdown voltage, i.e., a Zener voltage; the Zener voltage is configured to be higher than the normal operating voltage of the MicroLED chip and lower than the electrostatic discharge damage threshold voltage of the MicroLED chip.

[0010] Preferably, the Zener diode is in a reverse bias state when the MicroLED chip is working normally, exhibiting high impedance, and does not interfere with the normal electrical and optical functions of the MicroLED chip; when subjected to an electrostatic event, the Zener diode is broken down by a transient high voltage and quickly conducts, forming a low-impedance bypass path.

[0011] Preferably, the MicroLED chip includes RGB chips for emitting different colors of light, and each RGB chip is independently electrically connected to a corresponding Zener diode.

[0012] Preferably, the Zener diode is in the form of a bare chip, which is fixed and electrically connected to the MicroLED chip on the same packaging substrate by wire bonding, flip-chip bonding or eutectic bonding.

[0013] Preferably, the Zener diode is integrated into the flip-chip structure of the MicroLED chip, or an electrostatic discharge protection structure with Zener effect is formed on the same substrate of the MicroLED chip through semiconductor technology, forming a co-structure with the MicroLED chip.

[0014] A method for achieving high antistatic capability of a MicroLED package based on any one of the above claims includes the following steps: S1. Select a Zener diode with appropriate Zener voltage and power capacity based on the operating voltage of the MicroLED chip to be protected and the required electrostatic discharge withstand voltage level. S2. During the packaging process, the selected Zener diode is precisely electrically connected to the corresponding MicroLED chip so that the two are connected in parallel. S3. The Zener diode and MicroLED chip, which have been electrically connected, are packaged together to form a MicroLED package with enhanced anti-static capability.

[0015] Preferably, the electrical connection method in step S2 includes: placing the bare die of the Zener diode and the MicroLED chip side by side on the encapsulated substrate and connecting them in parallel by wire bonding; or, simultaneously soldering the Zener diode and the MicroLED chip to the corresponding pads on the encapsulation substrate by flip-chip bonding or eutectic bonding process.

[0016] Preferably, the Zener voltage of the Zener diode is configured to clamp the voltage applied to the MicroLED chip within a safe range when an electrostatic discharge event occurs, while providing a low-impedance discharge path for the electrostatic discharge current, thereby raising the upper limit of the electrostatic discharge withstand voltage of the MicroLED package to the kilovolt level.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention introduces active and integrated ESD protection by integrating a Zener diode at the packaging level. The active clamping characteristics of the Zener diode can respond quickly to sudden electrostatic events, fundamentally changing the ESD protection mechanism of MicroLED packages and realizing active protection for fragile chips.

[0018] 2. This invention utilizes the precise voltage clamping and efficient shunt capability of Zener diodes to significantly increase the upper limit of ESD withstand voltage of MicroLED packages from hundreds of volts, which is difficult to improve under traditional solutions, to kilovolts or even higher levels. This achieves a leap in anti-static capability, effectively overcomes the inherent ESD vulnerability of MicroLED chips due to their extreme miniaturization, and greatly reduces the risk of electrostatic damage during manufacturing and use.

[0019] 3. Due to the fundamental enhancement of the anti-static capability of the package itself, the damage rate of MicroLED chips caused by static electricity in key production processes such as mass transfer, packaging, and surface mount technology will be drastically reduced. This directly translates into a significant increase in product yield and reduces rework and scrap costs caused by ESD damage, thereby optimizing the production process and improving overall manufacturing efficiency and economic benefits.

[0020] 4. This invention achieves efficient ESD protection by integrating miniaturized Zener diodes (or by utilizing existing structures to achieve the Zener effect in a specific package), without relying on increasing the physical size of the MicroLED chip itself. This perfectly aligns with the core development direction of MicroLED technology, which pursues extreme miniaturization, high pixel density, and high pixels per inch, and resolves the long-standing contradiction between size and reliability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the MicroLED package structure integrating a Zener diode in this invention; Figure 2 This is a schematic diagram illustrating the ESD protection working principle of the Qizhongnan diode of the present invention; Figure 3 This is a flowchart of the method of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 Please see Figure 1-2 The present invention provides a technical solution: a MicroLED package with integrated electrostatic discharge protection device, comprising a package substrate and one or more MicroLED chips disposed on the package substrate, wherein each MicroLED chip is electrically connected to an independent Zener diode, the Zener diode is connected in parallel with the corresponding MicroLED chip, and integrated into the same package to provide electrostatic discharge protection for the MicroLED chip.

[0024] It should be noted that, in this embodiment, a Zener diode corresponding to the MicroLED chip is disposed within the package. That is, each MicroLED chip is independently electrically connected to a Zener diode, and the Zener diode is connected in parallel with the critical input / output port or power / ground terminal of the corresponding MicroLED chip. The Zener diode and the MicroLED chip are integrated into the same package, specifically for providing electrostatic discharge protection for the MicroLED chip.

[0025] Zener diodes have a preset reverse breakdown voltage, i.e., Zener voltage. The Zener voltage is configured to be higher than the normal operating voltage of the MicroLED chip and lower than the electrostatic discharge (ESD) damage threshold voltage of the MicroLED chip. When the MicroLED chip is operating normally, the Zener diode is in a reverse bias state, exhibiting high impedance, and does not interfere with the normal electrical and optical functions of the MicroLED chip. When subjected to an ESD event, the Zener diode is broken down by the transient high voltage and quickly conducts, forming a low-impedance bypass path. The MicroLED chip includes RGB chips for emitting different colors of light, and each RGB chip is independently electrically connected to a corresponding Zener diode. The Zener diode is in bare die form, and it is fixed and electrically connected to the MicroLED chip on the same packaging substrate by wire bonding, flip-chip bonding, or eutectic bonding. The Zener diode is integrated into the flip-chip structure of the MicroLED chip, or an ESD protection structure with Zener effect is formed on the same substrate of the MicroLED chip through semiconductor processes, forming a co-structure with the MicroLED chip.

[0026] It should be noted that, in this embodiment, the Zener diode is a semiconductor diode with precise reverse breakdown characteristics (Zener effect). When designing and selecting it, its key parameter—reverse breakdown voltage (i.e., Zener voltage)—is crucial. It is configured to satisfy the following relationship: < < , in, This is the normal operating voltage for the MicroLED chip. This is the electrostatic damage threshold voltage for MicroLED chips.

[0027] Based on the above configuration, the working state of this package is as follows: ① Normal operating state: When the MicroLED chip is in normal light-emitting state, the voltage applied across the circuit is lower than the Zener voltage of the Zener diode. At this time, the Zener diode is in reverse bias and exhibits extremely high impedance (the reverse leakage current is only in the microampere or nanoampere range). Therefore, the presence of the Zener diode does not interfere with the normal electrical driving and optical light-emitting functions of the MicroLED chip.

[0028] ② ESD Protection Status: When the package is subjected to an electrostatic discharge (ESD) event, the transient high voltage rises rapidly within nanoseconds. Once this transient voltage exceeds the preset Zener diode voltage, the Zener diode immediately undergoes avalanche breakdown and quickly conducts. At this time, the dynamic impedance of the Zener diode drops sharply to an extremely low value, forming a low-impedance bypass path. The large current generated by the ESD is efficiently shunt through this bypass path. Simultaneously, the Zener diode precisely clamps the voltage applied across the MicroLED chip at a safe Zener voltage level, thereby preventing high voltage from breaking down the microscopic PN junction structure of the MicroLED chip.

[0029] When a MicroLED chip includes RGB chips (red, green, and blue) for emitting different colors of light, each RGB chip is independently electrically connected to a corresponding Zener diode. Since the material systems and voltage withstand characteristics of the different color chips may vary slightly, a diode with a corresponding Zener voltage can be configured for each color chip to achieve optimal protection.

[0030] Example 2: Multiple Integration Methods of Zener Diodes The present invention does not impose strict limitations on the specific physical integration method of the nano-diode, as long as it is connected in parallel with the MicroLED chip. Several preferred embodiments are as follows: Method 1: Parallel mounting of bare chips (e.g.) Figure 1 (As shown) Zener diodes are presented as stand-alone bare chips. During packaging, the Zener diode bare chip and the MicroLED chip are placed side-by-side on the packaging substrate, and the two are electrically connected in parallel via wire bonding. Alternatively, for chips with bottom electrodes, they can be directly soldered to the corresponding pads using eutectic bonding. This method is mature and suitable for multi-chip module packaging.

[0031] Method 2: Flip-chip bonding integration For MicroLED chips using flip-chip bonding, Zener diodes can also be integrated using flip-chip bonding. In this case, the bumps of the Zener diode are connected to the pads on the packaging substrate, and the circuit layers inside the packaging substrate achieve parallel connection between the two. This integration method has low parasitic parameters and is suitable for high-frequency or high-speed driving scenarios.

[0032] Method 3: Donor Structure Integration In more advanced integrated solutions, the Zener diode is not a standalone device, but rather an electrostatic discharge (ESD) protection structure with the Zener effect directly formed on the same substrate as the MicroLED chip through semiconductor processes. For example, during the epitaxial layer growth of the MicroLED chip or during the fabrication of the driving circuit, an additional PN junction sharing the substrate with the MicroLED chip can be fabricated. This PN junction is configured to have a preset Zener breakdown characteristic. This "common" ESD protection unit can save space to the maximum extent, making it particularly suitable for MicroLED display panels that pursue extreme miniaturization.

[0033] Example 3: Method for Achieving High Antistatic Capability Please see Figure 3 The flowchart shown illustrates that, based on the aforementioned MicroLED package, this invention also provides a method for achieving high antistatic capability using a MicroLED package based on any of the above methods, comprising the following steps: S1. Select a Zener diode with appropriate Zener voltage and power capacity based on the operating voltage of the MicroLED chip to be protected and the required electrostatic discharge withstand voltage level. The Zener voltage of the Zener diode is configured to clamp the voltage acting on the MicroLED chip within a safe range when an electrostatic discharge event occurs, while providing a low-impedance discharge path for the electrostatic discharge current, thereby raising the upper limit of the electrostatic discharge withstand voltage of the MicroLED package to the kilovolt level.

[0034] It should be noted that in this embodiment, a Zener diode with appropriate Zener voltage and power capacity is selected based on the operating voltage of the MicroLED chip to be protected and the required electrostatic discharge withstand voltage level. The key to selection is that the Zener voltage must be higher than the chip's maximum operating voltage to ensure normal function is not affected, while it must be significantly lower than the chip's intrinsic breakdown voltage to ensure effective protection. Through precise selection, the Zener diode ensures that, in the event of an electrostatic discharge event, it can clamp the voltage within a safe range and provide a low-impedance discharge path for the current, thereby increasing the upper limit of the MicroLED package's ESD withstand voltage from the traditional several hundred volts to the kilovolt level.

[0035] S2. During the packaging process, the selected Zener diode and the corresponding MicroLED chip are precisely electrically connected to each other in parallel. The electrical connection methods include: placing the bare Zener diode chip and the MicroLED chip side by side on the encapsulation substrate and connecting them in parallel by wire bonding; or, simultaneously soldering the Zener diode and the MicroLED chip to the corresponding pads on the packaging substrate by flip-chip bonding or eutectic bonding processes.

[0036] It should be noted that in this embodiment, during the packaging process, the selected Zener diode and the corresponding MicroLED chip are precisely electrically connected to form a parallel topology. Specific connection methods include, but are not limited to: Wire bonding: The bare Zener diode chip and the MicroLED chip are placed side by side on the packaging substrate and connected in parallel by metal leads; Flip-chip / eutectic bonding: Zener diodes and MicroLED chips are simultaneously soldered onto corresponding pads on the packaging substrate using flip-chip or eutectic bonding processes, achieving leadless interconnection.

[0037] S3. The Zener diode and MicroLED chip, which have been electrically connected, are packaged together to form a MicroLED package with enhanced anti-static capability.

[0038] It should be noted that in this embodiment, the Zener diode and MicroLED chip, which are electrically connected, are encapsulated and protected as a whole. For example, a protective layer is formed around the chip by means of dispensing, molding, or covering with a transparent substrate, ultimately forming a MicroLED package with significantly enhanced antistatic capabilities.

[0039] In summary, this invention achieves active clamping and shunting of ESD events by integrating parallel Zener diodes into each MicroLED chip at the packaging level. This design not only improves the anti-static capability of the package by orders of magnitude but also does not sacrifice the miniaturization advantage of the chip. At the same time, it significantly improves the yield rate in the production process and the long-term reliability of the end product, and has good process compatibility and industrial promotion value.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A MicroLED package integrating electrostatic discharge protection devices, characterized in that, It includes a packaging substrate and one or more MicroLED chips disposed on the packaging substrate, wherein each MicroLED chip is electrically connected to an independent Zener diode, the Zener diode is connected in parallel with the corresponding MicroLED chip and integrated into the same package to provide electrostatic discharge protection for the MicroLED chip.

2. The MicroLED package with integrated electrostatic discharge protection device according to claim 1, characterized in that, The Zener diode has a preset reverse breakdown voltage, i.e., Zener voltage; the Zener voltage is configured to be higher than the normal operating voltage of the MicroLED chip and lower than the electrostatic discharge damage threshold voltage of the MicroLED chip.

3. The MicroLED package with integrated electrostatic discharge protection device according to claim 1, characterized in that, The Zener diode is in a reverse bias state and exhibits high impedance when the MicroLED chip is working normally. It does not interfere with the normal electrical and optical functions of the MicroLED chip. When subjected to an electrostatic event, the Zener diode is broken down by the transient high voltage and quickly conducts, forming a low impedance bypass path.

4. The MicroLED package with integrated electrostatic discharge protection device according to claim 1, characterized in that, The MicroLED chip includes RGB chips for emitting different colors of light, and each RGB chip is independently electrically connected to a corresponding Zener diode.

5. The MicroLED package with integrated electrostatic discharge protection device according to claim 1, characterized in that, The Zener diode is in bare chip form and is fixed and electrically connected to the MicroLED chip on the same packaging substrate by wire bonding, flip-chip bonding or eutectic bonding.

6. The MicroLED package with integrated electrostatic discharge protection device according to claim 1, characterized in that, The Zener diode is integrated into the flip-chip structure of the MicroLED chip, or an electrostatic discharge protection structure with Zener effect is formed on the same substrate of the MicroLED chip through semiconductor technology, forming a co-structure with the MicroLED chip.

7. A method for achieving high antistatic capability based on the MicroLED package according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Select a Zener diode with appropriate Zener voltage and power capacity based on the operating voltage of the MicroLED chip to be protected and the required electrostatic discharge withstand voltage level. S2. During the packaging process, the selected Zener diode is precisely electrically connected to the corresponding MicroLED chip so that the two are connected in parallel. S3. The Zener diode and MicroLED chip, which have been electrically connected, are packaged together to form a MicroLED package with enhanced anti-static capability.

8. The method for achieving high antistatic capability of a MicroLED package with integrated electrostatic discharge protection device according to claim 7, characterized in that, The electrical connection method in step S2 includes: placing the bare die of the Zener diode and the MicroLED chip side by side on the encapsulated substrate and connecting them in parallel by wire bonding; or, simultaneously soldering the Zener diode and the MicroLED chip to the corresponding pads on the encapsulation substrate by flip-chip bonding or eutectic bonding process.

9. The method for achieving high antistatic capability of a MicroLED package with integrated electrostatic discharge protection device according to claim 7, characterized in that, The Zener diode's Zener voltage is configured to clamp the voltage applied to the MicroLED chip within a safe range when an electrostatic discharge event occurs, while providing a low-impedance discharge path for the electrostatic discharge current, thereby raising the upper limit of the electrostatic discharge withstand voltage of the MicroLED package to the kilovolt level.

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