Synchronized testing of light-emitting diodes

Abstract

This invention provides a system and method for quality control testing of LEDs that increases the speed of testing for LED device arrays on wafers. [Solution] In one example of the test system and method, a probe pair is connected to a subset of multiple light-emitting diodes (LEDs) on a wafer. Current pulses are sequentially applied through the probe pair. Each current pulse energizes an individual LED or group of LEDs. A sequence of current pulses is activated at least partially simultaneously. Brightness measurements are detected using a stationary photodetector assembly to detect the light emitted by all of the subset of LEDs connected to the probe pair.

Description

[Technical Field]

[0001] [Background Art] The present application relates to systems and methods for reliable quality control testing for light emitting diode (LED) devices and components, and more specifically to techniques for synchronized testing of LEDs, for example, before singulation. [Description of Related Art]

[0002] Reliable quality control testing for LEDs often involves measurement of light output and / or efficiency. An LED light output test measures the light output generated by an LED. The test generally determines whether an LED emits light at the expected brightness and within the expected spectrum. However, one drawback of existing light output measurement methods is that they are often limited to measuring a single LED at a time. For example, one common method of measuring LED light output involves surrounding an individual LED with an integrating sphere and measuring the total amount of light the LED outputs into the integrating sphere. However, integrating spheres are limited to testing a single device at a time.

[0003] Another drawback of existing light output measurement techniques is that many LEDs, including micro LEDs (also referred to as MicroLED, mLED and / or μLED), are fabricated on a wafer and must be probe tested before singulation. Mounting an integrating sphere around an LED during probe testing is physically impractical. In addition, integrating sphere technology, and other existing techniques such as spatially distinguishing photodetectors, are impractically slow for LED device arrays with many LEDs due to the constant need to move the integrating sphere for each LED being tested.

[0004] As the foregoing illustrates, what is needed in the art is a system and method for quality control testing of LEDs that increases the speed of testing for LED device arrays on a wafer. [Summary of the Invention]

[0005] One embodiment of the present disclosure describes a system comprising a chuck for holding a wafer containing LEDs, a probe device including a pair of probes connected to a subset of the LEDs to be probed, a stationary photodetector assembly for detecting light emitted by all of the LED subsets to be probed, and at least one computing device for energizing the LED subsets to be probed by sequentially applying a plurality of energizing pulses synchronized with the timing of the luminance and / or spectral measurement of the LED test. Each pair of probes is connected to an individual LED. Each of the energizing pulses energizes an individual of the LEDs to be probed. The consecutive energizing pulses in the pattern are activated at least partially simultaneously (e.g., overlapping in time).

[0006] Further embodiments describe a computer implementation method and a non-temporary computer-readable medium storing instructions for performing the method, wherein the method comprises the steps of: connecting a plurality of probe pairs to a subset of a plurality of light-emitting diodes (LEDs) on a wafer; sequentially applying a plurality of energizing pulses through the plurality of probe pairs, wherein each of the plurality of energizing pulses energizes an individual of the subset of the plurality of LEDs, wherein consecutive energizing pulses are activated at least partially simultaneously; and synchronously detecting luminance measurements of one or more of the subset of the plurality of LEDs using a stationary photodetector assembly for detecting light emitted by all of the subset of the plurality of LEDs.

[0007] At least one technical advantage of the disclosed technology over the prior art is that the disclosed technology enables fast and reliable luminance testing of LEDs before pulverization. Another technical advantage is that the speed and efficiency of luminance testing are increased compared to existing technologies for luminance testing on wafers and / or before pulverization. These technical advantages represent one or more technical advancements over the prior art approach. [Brief explanation of the drawing]

[0008] To allow for a more detailed understanding of the above-described features of various embodiments, a more specific description of the concept of the present invention, briefly summarized above, may be given by reference to various embodiments, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings only show typical embodiments of the concept of the present invention and should therefore not be considered limiting in any way, and that other equally effective embodiments exist.

[0009] [Figure 1] This document illustrates exemplary LED test systems in various embodiments.

[0010] [Figure 2] Examples of subsets of wafers and LEDs that can be probed by the LED test system of Figure 1, according to various embodiments, are shown.

[0011] [Figure 3] Examples of multiple LED subsets within a single wafer sector of a wafer being probed by the LED test system of Figure 1, according to various embodiments, are shown.

[0012] [Figure 4] Examples of current and brightness graphs for individual LED tests using the LED test system shown in Figure 1, and for a subset of LEDs being probed according to various embodiments, are shown.

[0013] [Figure 5] Examples of current and luminance graphs for LED group tests using the LED test system shown in Figure 1, and for various embodiments of the probing LED subset, are shown.

[0014] [Figure 6] Examples of LED probe pairs and LEDs to be probed in the LED test system of Figure 1, according to various embodiments, are shown.

[0015] [Figure 7] This is a step-by-step flowchart of the method for individual LED testing using the LED testing system shown in Figure 1, according to various embodiments.

[0016] [Figure 8] This is a step-by-step flowchart of a method for LED group testing using the LED test system shown in Figure 1, according to various embodiments. [Modes for carrying out the invention]

[0017] The following description includes numerous specific details to provide a more complete understanding of various embodiments. However, it will be apparent to those skilled in the art that the concepts of the present invention can be implemented without one or more of these specific details.

[0018] The test systems described include LED test systems that perform testing of LEDs on a wafer, for example, before individualization and / or removal from the wafer. Individualization refers to cutting or dividing a substrate, such as a wafer, into multiple separate elements. In various examples, individualization involves performing scribing, sawing, laser cutting, and / or other operations to separate a set of devices on a substrate into individual devices. In this context, individual devices include LED devices containing one or more LEDs. Reliable quality control testing for LEDs often involves measuring optical power and / or efficiency. However, existing optical power measurement methods are limited to measuring a single LED at a time. For example, using an integrating sphere which is limited to testing a single LED device. Furthermore, many modern LEDs, including microLEDs, are manufactured on wafers. As a result, it is preferable to perform testing before individualization. However, existing optical power measurement techniques are not suitable for on-wafer testing. For example, measurement techniques such as integrating sphere techniques are physically impractical or impossible for on-wafer testing. The technique of spatially distinguishing photodetectors and similar devices using an integrating sphere is impractically slow for LED device arrays with many LEDs, such as micro-LED arrays. For example, existing techniques may probe a single LED at a time and / or energize multiple LEDs separately.

[0019] Some embodiments of this disclosure describe a system comprising a chuck for holding a wafer containing LEDs, a probe device including probe pairs connected to a subset of LEDs to be probed, a stationary photodetector assembly for detecting light emitted by all of the LED subsets to be probed, and at least one computing device for energizing the LED subsets to be probed by applying a plurality of sequential energizing pulses. Each probe pair is connected to an individual LED. Each of the energizing pulses energizes an individual of the LEDs to be probed. The sequential energizing pulses in this pattern are activated at least partially simultaneously (e.g., overlapping in time). Thus, the LED testing techniques described enable fast and reliable on-wafer luminance testing before individualization, while increasing the speed and efficiency of luminance testing compared to existing techniques.

[0020] In some embodiments, the wafer rests on a clear glass or other transparent wafer chuck, rather than a solid metal chuck commonly used in wafer probe systems. The combination of a glass chuck and a transparent LED substrate allows LED light to propagate through the chuck. A single high-speed photodetector is mounted below the wafer chuck. An optical guide transmits light from the entire area of ​​the probe set (e.g., XY, XZ, or other 2D area) to the photodetector. Thus, a portion of the light output of all LEDs is directed to the photodetector. The photodetector output is measured by an analog-to-digital converter, for example, contained in the photodetector device or a connected computing device. In some examples, the precise moment of sampling and conversion is initiated by a trigger signal from the computing device. The driver circuit for each LED site is a programmable VI (e.g., voltage-current) source that biases the LED to a specific value at a precise moment. Each test site is independently controlled so that output to any selected device, from none to all, can be realized. The control functions within the computing device determine which one (or more) LED outputs are energized and the precise moment to trigger the photodetector measurement. As a result, the energizing pulse is synchronized with the measurement value and / or time window associated with a particular LED. This synchronization allows the illumination of a single LED to be associated with the photodetector measurement of that particular LED. The energizing current drives of sequentially consecutive LEDs may overlap. However, this sequential timing gives dominance to the illumination of a particular LED, so that LED emits a stable light at the time of the luminance measurement. This overlap minimizes the total test time.

[0021] In operation, embodiments of the present disclosure move a prober and apply probe connections to a plurality of LEDs simultaneously. Next, the system energizes each LED (or group of LEDs) sequentially (and, in some cases, at least partially overlappingly) in a configured sequence or pattern. The system synchronously measures light output using a single high-speed photodetector that views the entire probe area. The system records the measured brightness, compares the measured brightness against a limit, and records a result (e.g., pass / fail) for an individual LED. This is rapidly repeated in succession for many LEDs. The prober is then moved to the next location on the wafer. A more detailed description is provided through the discussion of the figures below.

[0022] Figure 1 is an exploded view of an exemplary LED testing system 100 in accordance with various embodiments. The LED testing system 100 tests and / or comprises a wafer 102. The LED testing system 100 includes, but is not limited to, a wafer chuck 104, a computing device 106, a probe device 108, and a photodetector assembly 110. The probe device 108 includes, but is not limited to, two or more probe pairs 112. The wafer 102 includes, but is not limited to, one or more wafer sectors 114 that contain LEDs. The computing device 106 includes, but is not limited to, a processor 120, a system memory 122, a storage 124, an input / output (I / O) device interface 126, and an interconnect 128. The photodetector assembly 110 includes, but is not limited to, a photodetector 116, a light guide 118, and a spectrometer 132.

[0023] Wafer 102 refers to a slice of a semiconductor substrate including one or more wafer sectors 114 or regions containing LEDs to be tested by LED testing system 100. Semiconductor substrates used for LEDs include aluminum oxide (Al2O3, also known as sapphire), gallium nitride (GaN), gallium arsenide (GaAs), silicon (Si), aluminum nitride (AlN) and / or the like. In some embodiments, a transparent semiconductor substrate is used for a device to be tested using the LED testing system 100. Transparent semiconductor substrates include aluminum oxide, gallium nitride, gallium arsenide and others. The transparent semiconductor substrate is transparent (e.g., within a threshold value) to at least a portion of the visible light spectrum.

[0024] The wafer 102 and the LEDs on it are formed by various processes, including epitaxy, masking, doping, photolithography, and / or similar. The LEDs on the wafer 102 include micro-LEDs and other types of LEDs. Micro-LEDs refer to tiny self-emitting or self-illuminating LEDs that form individual pixel elements. Micro-LEDs are LEDs that have a size measured in microns, and are generally smaller than 100 micrometers, which is smaller than a conventional LED (e.g., 1 / 100th the size). In some examples, arrays of micro-LEDs are used to form pixels. However, in various embodiments, a particular wafer sector 114 contains a single color or type of LED, rather than an array of LEDs that form a complete pixel in a display or other end-use device. The LEDs in the wafer sector 114 are tested, individualized, or otherwise fragmented and removed from the wafer 102 for use and / or further processing. In some examples, LED subdivision involves separating a set of multiple LEDs from the wafer 102, or separating individual LEDs from the wafer 102 (e.g., fragmentation). The LEDs on wafer 102 illuminate in multiple directions, including toward the wafer chuck 104 and / or toward the wafer chuck 104. Each LED includes two (or more) contacts exposed on the surface of wafer 102 facing the probe device 108 and / or closer to the probe device 108 than toward the wafer chuck 104 and the photodetector assembly 110.

[0025] The wafer chuck 104 of the LED test system 100 holds the wafer 102 in place for testing. In various embodiments, the wafer chuck 104 is made of a transparent material, such as a transparent semiconductor material or substrate. In some embodiments, the wafer chuck 104 is made using the same material as the wafer 102. In other embodiments, the wafer chuck 104 is made using a different material than the wafer 102. The wafer chuck 104 holds the wafer 102 in place, for example, by creating a vacuum between the surface of the wafer 102 and the adjacent surface of the wafer chuck 104. For this purpose, some embodiments of the wafer chuck 104 include a pattern of holes and / or grooves from which air is removed using a pump or other device. The pump may be a subcomponent of the wafer chuck 104 and / or the LED test system 100. In some embodiments, the wafer chuck 104 is operable to move in multiple directions for testing and to connect a probe device 108 to the LEDs on the wafer 102. For example, the wafer chuck 104 moves laterally (in the indicated x and / or y directions and / or rotates in the xy plane) to align a set of LEDs in a wafer sector 114 with a corresponding and matched set of probe pairs 112 of the probe device 108. In some embodiments, the wafer chuck 104 moves in the y direction to connect a set of probe pairs 112 to a set of LEDs. Once testing of the set of LEDs is complete, the wafer chuck 104 moves in the z direction to disconnect the set of probe pairs 112 from the set of LEDs, and moves laterally in the x and / or y directions to align the set of probe pairs 112 with a new set of LEDs in the wafer sector 114 and / or move to a new wafer sector 114. In further embodiments, other components of the LED testing system 100 move, resulting in the probe device 108 and / or optical guide 118 moving vertically and the wafer chuck 104 moving laterally.

[0026] The computing device 106 is configured to implement one or more of various embodiments. In some examples, the computing device 106 individually controls a set of energizing pulses (e.g., current, voltage, power, etc.) for each LED connected to each probe pair 112 of the probe device 108. Each energizing pulse is provided using a different probe pair 112 of the probe device 108. As will be described in more detail with reference to Figures 4 and 5, the computing device 106 sequentially energizes the set of LEDs under test so that consecutive energizing pulses are activated at least partially simultaneously (e.g., overlapping in time). Alternatively, in some examples, a controller device, a subcomponent of the probe device 108, controls the energizing pulses for the LEDs connected to each probe pair 112 to sequentially energize the set of LEDs. The computing device 106, the controller device, and / or other components of the probe device may also work together to control the energizing pulses for the LEDs connected to each probe pair 112 to sequentially energize the set of LEDs. Furthermore, the computing device 106 is configured to receive the measured signal from the photodetector 116, compare the measured signal with one or more predetermined and / or configurable luminance thresholds (and optionally, spectral content thresholds), and record the quality control result (e.g., pass, fail, and / or similar) for each individual LED and / or group of LEDs based on the comparison.

[0027] In some embodiments, the computing device 106 includes a processor 120, memory 122, storage 124, an I / O device interface 126, and interconnects 128. The computing device 106 includes a desktop computer, a laptop computer, a smartphone, a personal digital assistant (PDA®), a tablet computer, or any other type of computing device configured to receive, input, and process data and optionally display images, and is suitable for carrying out one or more embodiments. The computing device 106 described herein is illustrative and any other technically feasible configuration is included within the scope of this disclosure.

[0028] The processor 120 includes a central processing unit (CPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), any suitable processor implemented as an artificial intelligence (AI) accelerator, any other type of processor, or a combination of different processors, such as a CPU configured to work with a GPU. Generally, the processor 120 may be any technically feasible hardware unit capable of processing data and / or executing software applications. Furthermore, in the context of this disclosure, the computing elements shown within the computing device 106 may correspond to a physical computing system (e.g., a system in a data center) or may be a virtual computing instance running in a computing cloud.

[0029] The I / O device interface 126 enables communication between the processor 120 and the I / O devices. Generally, the I / O device interface 126 includes essential logic for interpreting addresses corresponding to I / O devices generated by the processor 120. The I / O device interface 126 may also be configured to implement a handshake between the processor 120 and the I / O devices and / or generate interrupts associated with the I / O devices. The I / O device interface 126 may be implemented as any technically feasible CPU, ASIC, FPGA, or any other type of processing unit or device. I / O devices include devices that can provide input, such as keyboards, mice, touch-sensitive screens, microphones, remote controls, and cameras, and devices that can provide output, such as display devices. Additionally, I / O devices may include devices that can both receive input and provide output, such as touchscreens and Universal Serial Bus (USB) ports. I / O devices may be configured to receive various types of inputs from the end user of computing device 106 and to provide various types of outputs to the end user of computing device 106, such as displayed digital images or digital video or text. In some embodiments, one or more of the I / O devices are configured to connect computing device 106 to a network. The network includes any technically feasible type of communication network that enables data to be exchanged between computing device 106 and external entities or devices, such as a web server or another network computing device. For example, the network may include, among other things, a wide area network (WAN), a local area network (LAN), a wireless (WiFi) network and / or the Internet.

[0030] Memory 122 includes a random access memory (RAM) module, a flash memory unit, or any other type of memory unit, or a combination thereof. The processor 120, the I / O device interface 126, and the network interface are configured to read data from and write data to memory 122. Memory 122 includes various software programs that can be executed by the processor 120, including one or more LED test applications that perform individualized and / or group LED testing, and application data associated with the software programs.

[0031] Storage 124 includes non-volatile storage for applications and data and may include fixed or removable disk drives, flash memory devices, CD-ROMs, DVD-ROMs, Blu-Ray®, HD-DVDs, or other magnetic, optical, or solid-state storage devices. Storage 124 may be a disk drive storage device. Although shown as a single unit, storage 124 may be a combination of fixed and / or removable storage devices, such as fixed disk drives, floppy disk drives, tape drives, removable memory cards, or optical storage, network-attached storage (NAS), or storage area networks (SANs). A software program including one or more LED test applications that perform individualized and / or group LED testing may be stored in storage 114 and loaded into memory 122 when executed.

[0032] The interconnect 128 includes any technically feasible internal and / or external data buses, memory buses, system buses, expansion buses, and / or similar. The interconnect 128 includes a set of electrical paths that enable data, addresses, and control signals to be transferred between various components of the computing device 106 and / or external devices and components. Although discussed in the singular for clarity, the interconnect 128 is an example of one or more interconnects 128 that connect, for example, a processor 120 to memory 122 and / or storage 124, and a computing device 106 to other devices including probe devices 108, I / O devices, peripheral devices, other computing devices, and / or similar. In some embodiments, the interconnect 128 includes PCI Express (PCIe) connections for high-speed internal connections and Universal Serial Bus (USB) connections for connecting external devices.

[0033] The probe device 108 includes a card or other device containing multiple probe pairs 112 for connecting to LEDs on the wafer 102. Each probe pair 112 connects to an individual LED in the wafer sector 114. In some examples, the set of probe pairs 112 of the probe device 108 connects to the corresponding set of all LEDs in the wafer sector 114. In other examples, the set of probe pairs 112 connects to a subset of LEDs in the wafer sector 114. The probe device 108 and / or the computing device 106 store LED location data indicating the location of each of the wafer sector 114, each subset of LEDs in the wafer sector 114, and / or individual LEDs on the wafer. The probe device 108 and / or the computing device 106 use the LED location data to connect the probe pairs 112 to the set of LEDs on the wafer 102. Once a set of LEDs has been tested, the probe device 108 and / or computing device 106 use the LED location data to disconnect the probe pair 112, move one or more components of the LED test system 100 to another location, and connect the probe pair 112 to another set of LEDs.

[0034] In some embodiments, the optical guide 118 includes an optical fiber bundle, such as a group or bundle of individual optical fiber strands. In some embodiments, the group of optical fiber strands is held together by, for example, a jacket, sheath and / or the like. The first end of the optical guide 118 is positioned so that at least a portion of the light emitted by each of the LEDs in the wafer sector 114 and / or each of the LEDs connected to the probe pair 112 of the probe device 108 is incident on the first end of the optical guide 118. The second end of the optical guide 118 is positioned so that the light incident on the first end of the optical guide 118 is directed to a single photodetector 116.

[0035] The photodetector 116 or photosensor includes any device or sensor that detects light, such as a photodiode, avalanche photodiode, phototransistor, PIN photodiode, Schottky photodiode, other pn junction devices and / or similar. In some embodiments, the optical guide 118 includes a first subset of optical fiber strands that provide light to the photodetector 116, and a second subset of optical fiber strands that provide light to the spectrometer 132, indicated by a dashed line. The optical guide 118 is separated or branched to provide detected light to both the photodetector 116 and the spectrometer 132. In embodiments where the optical guide 118 branches to the photodetector 116 and the spectrometer 132, the subsets of optical fiber strands are together dispersed, interleaved, or otherwise incorporated so that the optical guide 118 provides each of the photodetector 116 and the spectrometer 132 with a set of optical fiber strands that receive light from all of the LEDs under test. In some embodiments, the spectrometer 132 is used for sampling tests on a configured or predetermined subset of the LEDs being tested. However, in other embodiments, the spectrometer 132 is used for all of the LEDs being tested.

[0036] The output signal of the photodetector 116 is measured by an analog-to-digital converter included in or connected to the photodetector 116 and / or the computing device 106. In some examples, the precise moment of sampling and conversion is initiated by a trigger signal from the computing device 106. In some examples, the drive circuit for each LED site is a programmable VI (e.g., voltage-current) source that biases the corresponding LED to a specific value at a precise moment. Each test site is independently controlled so that output to any selected device, from none to all, can be realized. Control functions within the computing device 106 and / or the probe device 108 determine which one (or more) LED outputs are asserted and the precise moment to trigger the measurement using the photodetector 116. This synchronization allows each individual LED's emission to be associated with the photodetector measurement of that same LED. The sequential current driving of the LEDs may overlap. However, this sequential timing gives dominance to a particular LED so that it emits a stable light at the time of luminance measurement. This overlap minimizes the total test time.

[0037] While the photodetector 116 measures the overall light intensity or brightness, the spectrometer 132 analyzes the light spectrum, identifying specific wavelengths of light. In some embodiments, the spectrometer 132 includes a dispersion element that separates wavelengths in the light provided through the light guide 118, and sensors such as a photodetector that measures the intensity of each of the separated wavelengths. As a result, the spectrometer 132 detects the spectral content of the light and provides a signal indicating the spectral content of the light to the computing device 106.

[0038] In one example of the operation of the LED test system 100, a wafer chuck 104 holds a wafer 102 containing LEDs, such as micro-LEDs. A probe device 108 includes a pair of probes 112 that connect to a subset of LEDs on wafer 102 to be probed. A photodetector assembly 110, including a photodetector 116 and / or an optical guide 118, is stationary (e.g., during testing of the subset of LEDs to be probed) relative to wafer 102 and / or wafer chuck 104 to detect the light emitted by each LED in the subset of LEDs to be probed. A computing device 106 (and / or the controller of the probe device 108) sequentially energizes the subset of LEDs to be probed by applying synchronized energizing pulses, such as a controlled current, voltage, or power waveform synchronized with the measurement timing. Individual energizing pulses energize individual LEDs in the subset of LEDs to be probed, while consecutive energizing pulses are activated so that they overlap in time.

[0039] The optical guide 118 transmits the probe pair 112 and the entire area (e.g., XY as shown) of the wafer sector 114 corresponding to the LED under test. In this way, a portion of the light output of all the LEDs is brought to a photodetector 116, which may be a single photodetector 116. The photodetector 116 detects the light emitted by the LED under test over the duration of the test. Since any two consecutive energizing pulses are activated at least partially, but not entirely simultaneously (e.g., overlapping), the associated LEDs also emit light at least partially simultaneously. The resulting light output passes through the optical guide 118 to the photodetector 116, which detects the light intensity and provides one or more optical measurement signals over time, such as a continuous curve and / or periodic light intensity values. The photodetector 116 provides the indication of the detected light to a computing device 106 as one or more optical (e.g., luminance) measurement signals.

[0040] The computing device 106 compares one or more optical measurement signals to one or more luminance thresholds (e.g., low and high) to determine whether one or more optical measurement signals remain within an acceptable range. If one or more optical measurement signals indicate that the light detected by the photodetector 116 remains within an acceptable range throughout the entire total test period of the LEDs being tested, then all LEDs are acceptable. If all LEDs are acceptable, the computing device 106 records a quality control result such as pass, acceptable, and / or similar.

[0041] However, if the optical measurement signal is outside one or more luminance thresholds (e.g., less than or greater than ), the computing device 106 identifies the LED associated with the abnormal performance and records the quality control result, such as fail, unacceptable, and / or similar. The computing device 106 identifies at least one time when the optical measurement signal is outside one or more luminance thresholds. The computing device 106 maps this time to a time window for the specific LED, according to an LED identifier, probe pair identifier, and / or similar. The LED identification time window is the period during which a particular LED is a primary light source based on the pattern of energizing pulses applied by the computing device 106 (and / or probe device 108). In some embodiments, the time window is the period during which the magnitude of the energizing pulse for a particular LED is greater than the individual magnitudes of other energizing pulses. The time window is mapped to the energizing pulse for the specific LED. The computing device 106 records the fail quality control result for this LED. Next, the LED test system 100 moves one or more components, such as the wafer chuck 104, probe device 108, and / or optical guide 118, to the next wafer sector 114. The operation of the LED test system 100 is faster than that of existing embodiments.

[0042] In some embodiments, the operation of the LED test system 100 includes simultaneously illuminating LED groups, for example, two, three, four, or any number of LEDs under test. Each LED group has the same number of LEDs assigned to it, and as a result, the resulting composite light intensity is similar for each LED group that is functioning correctly (e.g., within one or more thresholds). If one or more LEDs in an LED group are not functioning correctly, the overall photosynthetic luminance or intensity decreases and / or increases. All LEDs in all LED groups are acceptable if one or more optical measurement signals indicate that the composite light detected by the photodetector 116 remains within an acceptable range throughout the entire total test period of the LED groups under test. If all LEDs in all LED groups are acceptable, the computing device 106 records a quality control result, such as pass, acceptable, and / or similar. If the group optical measurement signals are outside one or more group luminance thresholds, the computing device 106 identifies at least one time when the group optical measurement signals are outside one or more group luminance thresholds. Generally, the group luminance threshold is greater than the individual LED luminance threshold because a larger number of LEDs are illuminated simultaneously by a single energizing pulse. The computing device 106 maps the time to a time window for a particular LED group according to an LED group identifier, probe pair identifier, and / or similar. The LED group identification time window is the period during which a particular LED group is the primary light source, based on the pattern of energizing pulses applied by the computing device 106 (and / or probe device 108). The computing device 106 then performs an individual LED test for the LEDs within the LED group. This individual LED test functions as discussed earlier. Since the entire LED group has failed, one or more LEDs may be associated with one or more optical measurement signals outside the individual luminance thresholds.The computing device 106 identifies the time when the optical measurement signal for individual or individualized testing is outside an individual brightness threshold and maps that time to one or more LEDs.

[0043] In one example, including a spectrometer 132, the light output from one or more of the LEDs being tested (e.g., all LEDs, or a subset corresponding to a sampling test) passes through the optical guide 118 to the spectrometer 132. The spectrometer 132 identifies the spectral content of the light and provides one or more spectral content measurement signals indicating one or more wavelengths individually and / or as a wavelength range. The spectrometer 132 provides the spectral content indications to the computing device 106 as one or more spectral content measurement signals.

[0044] Figure 2 shows examples of wafers 102 and LED subsets 202 to be probed by the LED test system 100 of Figure 1, according to various embodiments. Wafer 102 includes, but is not limited to, one or more wafer sectors 114. Wafer sectors 114 include, but is not limited to, an LED subset 202 to be probed, and the LED subset 202 to be probed includes, but is not limited to, one or more LEDs numbered from 1 to 48.

[0045] The LED subset 202 being probed is a set of LEDs connected to the corresponding set of LED probe pairs 112. Each LED is connected to an LED probe pair 112, and as a result, the LED probe pair 112 provides a flow of current through the LEDs. In the example shown, the LED subset 202 being probed is the set of all LEDs in the wafer sector 114. However, in other examples, the LED subset 202 being probed is a subset of LEDs in the wafer sector 114 that are connected to the corresponding set of LED probe pairs 112.

[0046] During operation, the LED test system 100 in Figure 1 connects probe pairs 112 to each of the 48 LEDs from 1 to 48, resulting in 48 probe pairs 112 being simultaneously connected to these 48 LEDs. For illustrative purposes, the example in Figure 2 shows a set of 48 LEDs and illustrates a set of 48 corresponding probe pairs 112. However, the LED test system 100 may include any number of probe pairs 112 for connection to any number of LEDs. Next, the LED test system 100 energizes each LED sequentially from 1 to 48. The LED test system 100 synchronously measures the light output using a photodetector 116 that views the entire probe area corresponding to LEDs 1 to 48. The system records the measured luminance, compares the measured luminance to a limit, and records the result for each individual LED. Next, the probe device 108 is moved to the next wafer sector 114 on wafer 102.

[0047] Figure 3 shows an example of multiple LED subsets 302 within a single wafer sector 114 of a wafer 102 being probed by the LED test system 100 of Figure 1, according to various embodiments. The wafer 102 includes, but is not limited to, one or more wafer sectors 114. The wafer sector 114 includes, but is not limited to, two or more LED subsets 302a and 302b (LED subset 302). LED subset 302a includes, but is not limited to, LEDs numbered from 1a to 24a. LED subset 302b includes, but is not limited to, LEDs numbered from 1b to 24b.

[0048] In this example, a single wafer sector 114 contains multiple LED subsets 302. In some embodiments, the density of LEDs within wafer sector 114 is greater than the density of probe pairs 112 of probe device 108. As a result, the LEDs within wafer sector 114 are separated into multiple testable LED subsets 302. If LED subset 302a is connected to a corresponding set of LED probe pairs 112, then LED subset 302a is the LED subset to be probed. If LED subset 302b is connected to a corresponding set of LED probe pairs 112, then LED subset 302b is the LED subset to be probed.

[0049] During operation, the LED test system 100 in Figure 1 connects probe pairs 112 to each of the LEDs from 1a to 24a, resulting in 24 probe pairs 112 being simultaneously connected to these 24 LEDs in the LED subset 302a. Next, the LED test system 100 sequentially energizes each LED from 1a to 24a. The LED test system 100 synchronously measures the light output using a photodetector 116 that views the entire probe area corresponding to LEDs 1a to 24a and / or wafer sector 114. The system records the measured luminance, compares the measured luminance to a limit, and records the result for each individual LED. Next, the probe device 108 is moved to the next LED subset 302b within the same wafer sector 114.

[0050] The LED test system 100 connects probe pairs 112 to each of the LEDs from 1b to 24b, resulting in 24 probe pairs 112 being simultaneously connected to these 24 LEDs of the LED subset 302b. Next, the LED test system 100 sequentially energizes each LED from 1b to 24b. The LED test system 100 synchronously measures the optical output using a photodetector 116 that views the entire probe area corresponding to LEDs 1b to 24b and / or wafer sector 114. Next, the probe device 108 is moved to the next wafer sector 114.

[0051] Figure 4 shows examples of current and luminance graphs 400 for individual LED tests using the LED test system 100 of Figure 1, and a subset of LEDs to be probed 202 according to various embodiments. The subset of LEDs to be probed 202 includes, but is not limited to, one or more LEDs numbered from 1 to 48. Graph 400 includes, but is not limited to, one or more energizing pulses 402, a lower luminance threshold 404, an upper luminance threshold 406, one or more LED identification boundary times 408, one or more LED identification time windows 410, and a luminance curve 412.

[0052] The upper portion of graph 400 shows energizing pulses 402-1, 402-2, 402-10, and 402-48 corresponding to LEDs 1, 2, 10, and 48, respectively. The LED test system 100 also applies other energizing pulses 402. For example, energizing pulse 402-1 energizes LED 1, energizing pulse 402-2 energizes LED 2, energizing pulse 402-3 (not shown) energizes LED 3, energizing pulse 402-4 (not shown) energizes LED 4, and so on. Each energizing pulse 402 corresponds to a current curve, voltage curve, power curve, or other measurement of a programmable VI source that biases the corresponding LED to a specific value at a precise time according to the energizing pattern or sequence.

[0053] Furthermore, the lower portion of graph 400 shows the luminance curve 412 detected by the photodetector 116 and / or analyzed using the computing device 106. The lower portion of graph 400 also shows the individual luminance of LEDs 1 to 48, indicated by dashed lines. The luminance curve 412 is the result of superimposing the light outputs of LEDs 1 to 48 generated from overlapping energizing pulses 402.

[0054] The lower luminance threshold 404 and the upper luminance threshold 406 are thresholds stored by the computing device 106. In some embodiments, at least one subset of the LED identification boundary time 408 is the time when consecutive (e.g., sequentially adjacent, even if partially overlapping) energizing pulses 402 are equivalent to one another. In some embodiments, the LED identification boundary time 408 for the first LED (e.g., LED1) is at the start time "0" of the energizing pattern, and the LED identification boundary time 408 for the last LED (e.g., LED48) is at the end time of the energizing pattern. In some embodiments, the LED identification boundary time 408 for the first LED (e.g., LED1) is the time when the energizing pulse for the first LED intersects with the lower threshold energizing value (e.g., lower threshold current), and the LED identification boundary time 408 for the last LED (e.g., LED48) is the time when the energizing pulse for the last LED intersects with the lower threshold energizing value. The LED identification boundary time 408 shown in Graph 400 corresponds to the LED identification boundary time 408 between consecutive energizing pulses 402-1 and 402-2. For clarity, other LED identification boundary times 408 are not labeled. In some embodiments, the LED identification boundary time 408 is the time when the LED outputs of consecutive LEDs in the energizing pattern are equivalent to each other.

[0055] The LED identification time window 410 is the time window or period between two LED identification boundary times 408. The specifically indicated LED identification time window 410 is the LED identification time window 410 for LED 10. For clarity, other LED identification time windows 410 are not labeled.

[0056] The computing device 106 causes the LED test system 100 to start a test in which energizing pulses 402 are applied over time according to the energizing pattern. The computing device 106 determines that the luminance curve 412 exceeds the lower luminance threshold 404, and then monitors the luminance curve 412 to determine whether the luminance curve 412 remains within an acceptable range between the lower luminance threshold 404 and the upper luminance threshold 406.

[0057] In the example shown, the luminance curve 412 remains within an acceptable range up to the LED identification time window 410 of LED 10. The computing device 106 compares the value of the luminance curve 412 or the corresponding luminance measurement signal with the lower luminance threshold 404 and the upper luminance threshold 406. In this example, the computing device 106 determines that the value or magnitude of the luminance curve 412 is less than the lower luminance threshold 404. The computing device 106 identifies the timestamp of the luminance curve 412 or the corresponding luminance measurement signal and determines the time for which the luminance curve 412 is less than the lower luminance threshold 404. The computing device 106 compares this time with the LED identification time window 410 and / or LED identification boundary time 408 specified in the data describing the energization pattern.

[0058] The data describing the energization pattern specifies one or more LED identification boundary times 408 and / or one or more LED identification time windows 410. The computing device 106 determines that a particular LED identification time window 410 corresponds to a time when the luminance curve 412 is less than the lower luminance threshold 404. The data describing the energization pattern includes mappings that map the LED identification time windows 410 to the corresponding LEDs and / or probe pairs 112. In some embodiments, the mapping maps the LED identification time windows 410 to the probe pairs 112 and the probe pairs 112 to the LEDs. The mapping of the probe pairs 112 to the LEDs is updated when the probe device 108 is moved to a different set of LEDs.

[0059] The computing device 106 identifies LEDs that are mapped to the LED identification time window 410 when the luminance curve 412 is less than the lower luminance threshold 404. The computing device 106 determines that LED 10 failed the test and records the failure or unacceptable quality control result for LED 10. The computing device 106 determines that LEDs 1 to 9 and 11 to 48 passed the test and records the pass or acceptable quality control results for LEDs 1 to 9 and 11 to 48.

[0060] Figure 5 shows examples of current and luminance graphs 500 for LED group testing using the LED test system 100 of Figure 1, with respect to various embodiments, including a subset of LEDs to be probed 202 and LEDs to be tested using the LED test system 100 of Figure 1. The subset of LEDs to be probed 202 includes, but is not limited to, one or more LEDs numbered from 1 to 48. Graph 500 includes, but is not limited to, one or more group energization pulses 502, a lower group luminance threshold 504, a higher group luminance threshold 506, one or more LED group identification boundary times 508, one or more LED group identification time windows 510, and a group luminance curve 512.

[0061] In the embodiments shown, individual LEDs are numbered as shown in Figure 5. LED groups are indicated by bold numbers and outlined with thick lines. For example, LED group 1 includes LEDs 1, 2, 7, and 8; LED group 2 includes LEDs 3, 4, 9, and 10; LED group 3 includes LEDs 5, 6, 11, and 12; LED group 4 includes LEDs 13, 14, 19, and 20, and so on.

[0062] The upper portion of Graph 500 shows group energizing pulses 502-1, 502-2, 502-10, and 502-12, corresponding to LED groups 1, 2, 10, and 12, respectively. The LED test system 100 also applies other group energizing pulses 502. For example, group energizing pulse 502-1 energizes LED group 1, group energizing pulse 502-2 energizes LED group 2, group energizing pulse 502-3 (not shown) energizes LED group 3, group energizing pulse 502-4 (not shown) energizes LED group 4, and so on. Each group energizing pulse 502 corresponds to a current curve, voltage curve, power curve, or other measurement of a programmable VI source that biases the corresponding LED (and / or LED group) to a specific value at a precise time according to the group energizing pattern or sequence.

[0063] In some embodiments, the LEDs within an LED group are connected, for example, using the circuitry of a probe pair 112, a probe device 108, and / or other circuits, so that a single group energizing pulse 502 energizes the LEDs within the LED group. However, in other examples, the energizing pattern includes a set of simultaneously applied (e.g., fully overlapping) energizing pulses for each LED group, resulting in four distinct but simultaneously applied energizing pulses activating LED group 1, four distinct but simultaneously applied energizing pulses activating LED group 2, and so on. Each individual LED is connected to a separate probe pair 112.

[0064] The lower portion of graph 500 shows the group luminance curve 512 detected by the photodetector 116 and / or analyzed using the computing device 106. In some examples, multiple LEDs are energized simultaneously, so the value or magnitude of the group luminance curve 512 is greater than the luminance curve 412 of the individual LEDs (Figure 4). The lower portion of graph 500 also shows the individual luminance of each of the LED groups 1 to 12, indicated by dashed lines. The luminance curve 512 is the result of superimposing the light outputs of LED groups 1 to 12, which are generated from overlapping group energization pulses 502.

[0065] The group lower brightness threshold 504 and the group upper brightness threshold 506 are thresholds stored by the computing device 106. In some examples, multiple LEDs are powered simultaneously, so the value of the group lower brightness threshold 504 is greater than the lower brightness threshold 404 of the individual LEDs (Figure 4). In some examples, multiple LEDs are powered simultaneously, so the value of the group upper brightness threshold 506 is greater than the upper brightness threshold 406 of the individual LEDs (Figure 4).

[0066] In some embodiments, at least one subset of the LED group identification boundary time 508 is the time when consecutive (e.g., sequentially adjacent, even if partially overlapping) group energizing pulses 502 are equivalent to one another. Other LED group identification boundary times 508 may include the start time "0" and end time of the pulse energizing pattern. In some embodiments, the LED identification boundary time 508 for a first LED group (e.g., LED group 1) is the time when the energizing pulse for the first LED group intersects the lower threshold energizing value, and the LED identification boundary time 508 for the last LED group (e.g., LED group 12) is the time when the energizing pulse for the last LED group intersects the lower threshold energizing value. The LED identification boundary times 508 shown in Graph 500 correspond to the LED identification boundary times 508 between consecutive group energizing pulses 502-1 and 502-2. For clarity, other LED group identification boundary times 508 are not labeled. In some embodiments, the LED group identification boundary time 508 is the time at which the LED group brightness outputs of consecutive LED groups in the energized pattern are equal to each other.

[0067] The LED group identification time window 510 is the time window or period between two LED group identification boundary times 508. Specifically, the LED group identification time window 510 is the LED group identification time window 510 for LED group 10 corresponding to LEDs 37, 38, 43, and 44. For clarity, other LED group identification time windows 510 are not labeled.

[0068] The computing device 106 initiates a test in the LED test system 100, applying group energizing pulses 502 over time according to the energizing pattern. The computing device 106 determines that the group luminance curve 512 exceeds the group lower luminance threshold 504, and then monitors the group luminance curve 512 to determine whether the group luminance curve 512 remains within an acceptable range between the group lower luminance threshold 504 and the group upper luminance threshold 506.

[0069] In the example shown, the group luminance curve 512 remains within an acceptable range up to the LED group identification time window 510 of LED group 10. The computing device 106 compares the value of the luminance curve 512 or the corresponding luminance measurement signal with the group lower luminance threshold 504 and the group upper luminance threshold 506. In this example, the computing device 106 determines that the value or magnitude of the group luminance curve 512 is less than the group lower luminance threshold 504. The computing device 106 identifies the timestamp of the group luminance curve 512 or the corresponding luminance measurement signal and determines the time for which the group luminance curve 512 is less than the group lower luminance threshold 504. The computing device 106 compares this time with the LED group identification time window 510 and / or LED group identification boundary time 508 specified in the data describing the energization pattern.

[0070] The data describing the energization pattern specifies one or more LED group identification boundary times 508 and / or one or more LED group identification time windows 510. The computing device 106 determines that a particular LED group identification time window 510 corresponds to a time when the group brightness curve 512 is less than the lower brightness threshold 404. The data describing the energization pattern includes mapping the LED group identification time window 510 to the corresponding LED group and / or corresponding set of LEDs. In some embodiments, the mapping maps the LED group identification time window 510 to a set of probe pairs 112, and each probe pair 112 to an LED.

[0071] The computing device 106 determines that LED group 10 is mapped to the LED group identification time window 510 when the group luminance curve 512 is less than the group lower luminance threshold 504. The computing device 106 determines that LED group 10 failed the test and records the fail or unacceptable quality control result for LED group 10. The computing device 106 determines that LED groups 1 to 9, 11 and 12 passed the test and records the pass or acceptable quality control results for LED groups 1 to 9, 11 and 12 (and / or the corresponding individual LEDs).

[0072] Since the duration of each LED group energizing pulse 502 can be as short in time as the energizing pulse 402 for a single LED, group testing is faster than individual testing. However, because the group testing performed by the LED testing system 100 uses a single photodetector 116, the group testing described above does not identify which individual LEDs in LED group 10 failed. As a result, the computing device 106 performs individual LED testing by sequentially applying the energizing pulse 402 to individual LEDs, as described with respect to Figure 4, but limits the LEDs in the individual testing to those of one or more LED groups that failed as identified in the group testing. In the example shown, since only LED group 10 failed, the computing device 106 performs individual testing limited to LEDs 37, 38, 43, and 44. The computing device 106 determines which one or more of LEDs 37, 38, 43, and 44 passed the individual testing and which one or more of LEDs 37, 38, 43, and 44 failed the individual testing. The computing device 106 records the individual quality control results for each of the LEDs 37, 38, 43, and 44.

[0073] Figure 6 shows an example of an LED probe pair 112 of the LED test system 100 of Figure 1 according to various embodiments. The shown portion of the LED test system 100 includes, but is not limited to, a wafer chuck 104, a wafer 102, one or more LED probe pairs 112a, 112b, 112c and 112d (LED probe pairs 112) and one or more LEDs 602a, 602b, 602c and 602d (LEDs 602).

[0074] Each LED probe pair 112 connects probe device 108 (Figure 1) to LED 602. For example, LED probe pair 112a connects probe device 108 to LED 602a, LED probe pair 112b connects probe device 108 to LED 602b, LED probe pair 112c connects probe device 108 to LED 602c, and LED probe pair 112d connects probe device 108 to LED 602d. Probe device 108 contains any number of probe pairs 112. For clarity, probe device 108 is omitted from Figure 6.

[0075] Figure 7 is a flowchart of the steps of a method for individual LED testing using the LED testing system of Figure 1, according to various embodiments. Although the steps of the method are described in conjunction with the systems and components of Figures 1 to 6, those skilled in the art will understand that any system configured to perform the steps of the method in any order is within the scope of the present invention.

[0076] As shown, Method 700 begins in step 702, in which the LED test system 100 simultaneously connects probe pairs 112 to corresponding sets of LEDs 602 on wafer 102. The LED test system 100 includes a wafer chuck 104 that holds wafer 102. Wafer 102 contains LEDs 602. The LED test system 100 includes a probe device 108 that uses one or more probe pairs 112 to simultaneously connect to a subset of LEDs 202 to be probed that corresponds to a subset of LEDs 602 on wafer 102. The LED test system 100 includes a photodetector assembly 110 that is stationary when an energizing pattern is applied. The photodetectors 116 and / or optical guides 118 of the photodetector assembly 110 are positioned to detect light emitted by all of the LED subsets 202 to be probed. Individual probe pairs 112 connect to individual LEDs 602 of the LED subsets 202 to be probed.

[0077] In step 704, the LED test system 100 sequentially applies energizing pulses 402 to the LEDs 602 of the LED subset 202 being probed on the wafer 102. The LED test system 100 includes a computing device 106 that sequentially energizes the LED subset 202 being probed by applying a plurality of energizing pulses 402. In some embodiments, the computing device 106 and / or the probe device 108 operate individually or in coordination to sequentially apply the energizing pulses 402. Each of the energizing pulses 402 energizes an individual LED 602 ​​of the LED subset 202 being probed. In some embodiments, the consecutive energizing pulses of the energizing pattern are activated at least partially simultaneously (e.g., overlapping in time). The computing device 106 causes the LED test system 100 to perform a test of the LED subset 202 being probed. The test applies the energizing pulses 402 over time according to the energizing pattern.

[0078] In step 706, the LED test system 100 synchronously monitors luminance measurements using a photodetector 116. The photodetector 116 and / or optical guide 118 of the photodetector assembly 110 are positioned to detect light emitted by all of the LEDs 602 of the LED subset 202 being probed. The photodetector 116 detects light emitted from the LEDs 602 as a result of energizing pulses applied to the LEDs 602. Since the photodetector 116 and / or optical guide 118 of the photodetector assembly 110 are positioned to detect light emitted by all of the LEDs 602, a single photodetector 116 is used for all luminance measurements. In some embodiments, the optical guide 118 is a branched optical guide, and the photodetector assembly 110 further includes a spectrometer 132 that measures the spectral content (e.g., wavelength) of one or more of the LEDs 602. In some embodiments, since all LEDs 602 within a particular area of ​​wafer 102 may have similar wavelength emission, spectral content detection is a sampling inspection of pre-configured or selected LEDs 602.

[0079] Brightness measurements are synchronized with the energization pattern based on the timing data of the sequential energization pattern. For example, computing device 106 identifies and / or triggers a brightness measurement at one time within the LED timing window of LED 602. Computing device 106 receives one or more brightness measurement signals from photodetector 116 and monitors brightness by comparing one or more brightness measurement signals with one or more brightness thresholds. Brightness thresholds include one or more of the lower brightness threshold 404 and / or upper brightness threshold 406. Optionally, computing device 106 receives one or more spectral content measurement signals from spectrometer 132 and monitors spectral content by comparing one or more spectral content measurement signals with one or more spectral content or wavelength thresholds. Wavelength thresholds include one or more of the lower wavelength threshold and / or upper wavelength threshold. In some embodiments, LED test system 100 measures and monitors the spectral content of a subset of LED 602 ​​of the LED subset 202 being probed. In some embodiments, the subset corresponds to one spectral content measurement for every "N" luminance measurements. In some embodiments, an enterprise designates a set of LEDs 602 on wafer 102 for spectral content measurement, for example, according to an LED identifier, and the LED test system 100 limits the spectral content measurement to the designated LEDs 602.

[0080] In step 708, the LED test system 100 records the test results for each LED 602 ​​of the LED subset 202 being probed. For example, the computing device 106 determines whether a portion of the luminance curve 412 corresponding to each LED 602 ​​remains within an acceptable range between the lower luminance threshold 404 and the upper luminance threshold 406. The data stored in the computing device 106 logically associates each LED 602 ​​with a portion of the luminance curve 412 corresponding to an LED identification time window 410 and / or between two LED identification boundary times 408. For example, data describing a current flow pattern specifies one or more LED identification boundary times 408 and / or one or more LED identification time windows 410.

[0081] In some cases, the computing device 106 determines that the luminance curve 412 remains within an acceptable range throughout the test, and records the pass or pass test result for each LED 602. However, if the computing device 106 determines that one or more portions of the luminance curve 412 are below the lower luminance threshold 404 and / or above the upper luminance threshold 406, the computing device 106 records the fail or fail test result for one or more LEDs 602 corresponding to one or more portions of the luminance curve 412. The computing device 106 determines one or more times when the luminance curve 412 is outside an acceptable range, and uses data describing the energization pattern to identify one or more LEDs 602 based on those one or more times.

[0082] In step 710, the LED test system 100 disconnects the probe pair 112 from the currently probing LED subset 202 and moves it to another (e.g., the next) LED subset 202 to be probed on the wafer 102. In some embodiments, the LED test system 100 disconnects the probe pair 112 by moving the wafer chuck 104 away from the probe device 108. The LED test system 100 moves the wafer chuck 104 laterally (e.g., on the plane of the surface of the wafer chuck 104 in contact with the wafer 102) so that the probe pair 112 and the optical guide 118 are aligned with the next LED subset 202 to be probed on the wafer 102. The LED test system 100 connects the probe pair 112 to the next LED subset 202 to be probed by moving the wafer chuck 104 toward the probe device 108. The process then moves to stage 702, where the LED test system 100 connects to the next LED subset 202 of wafer 102 to be probed.

[0083] Figure 8 is a flowchart of the steps of a method for LED group testing using the LED test system of Figure 1, according to various embodiments. Although the steps of the method are described in conjunction with the systems and components of Figures 1 to 6, those skilled in the art will understand that any system configured to perform the steps of the method in any order is within the scope of the present invention.

[0084] As shown, Method 800 begins in step 802, where the LED test system 100 simultaneously connects probe pairs 112 to corresponding sets of LEDs 602 on wafer 102. The LED test system 100 includes a wafer chuck 104 that holds wafer 102. Wafer 102 contains LEDs 602. The LED test system 100 controls these LEDs 602 in an LED group. The LED test system 100 includes a probe device 108 that uses one or more probe pairs 112 to simultaneously connect to a set of LEDs 602 to be probed, corresponding to a subset of LEDs 602 on wafer 102. The energizing pattern logically groups the sets of LEDs 602 into an LED group. The LED test system 100 includes a photodetector assembly 110 that is stationary when the energizing pattern is applied as a group-based test of the LEDs 602. Individual probe pairs 112 connect to individual LEDs 602 in the LED subset 202 to be probed. In some embodiments, the energizing pattern includes a set of energizing pulses applied simultaneously (e.g., fully overlapping) for each LED group, resulting in multiple distinct but simultaneously applied energizing pulses activating the LEDs 602 in the LED group. In some embodiments, the LEDs 602 in the LED group are connected, for example, using the circuitry of a probe pair 112, probe device 108, and / or other circuits, so that a single group energizing pulse 502 energizes the LEDs 602 in the LED group. In any example, the photodetectors 116 and / or optical guides 118 of the photodetector assembly 110 are positioned to detect the light emitted by all of the LED subset 202 being probed.

[0085] In step 804, the LED test system 100 sequentially applies group energizing pulses 502 to the LED groups of the LED subset 202 to be probed on the wafer 102. The LED test system 100 includes a computing device 106 that sequentially energizes the LED subset 202 to be probed by applying a plurality of group energizing pulses 502. In some embodiments, the computing device 106 and / or the probe device 108 operate individually or in coordination to sequentially apply the group energizing pulses 502. The group energizing pulses 502 energize the LED groups of the LED subset 202 to be probed. In some embodiments, the consecutive group energizing pulses 502 in the energizing pattern are activated at least partially simultaneously (e.g., overlapping in time). The computing device 106 causes the LED test system 100 to perform a test of the LED subset 202 to be probed. The test applies the group energizing pulses 502 over time according to the energizing pattern.

[0086] In step 806, the LED test system 100 monitors group luminance measurements using a photodetector 116. The photodetector 116 and / or optical guide 118 of the photodetector assembly 110 are positioned to detect light emitted by all LEDs 602 of all LED groups of the LED subset 202 being probed. The photodetector 116 detects light emitted from the LED group as a result of a group energizing pulse 502 applied to the LED group. Since the photodetector 116 and / or optical guide 118 of the photodetector assembly 110 are positioned to detect light emitted by all LED groups, a single photodetector 116 is used for all luminance measurements. In some embodiments, the optical guide 118 is a branched optical guide, and the photodetector assembly 110 further includes a spectrometer 132 for measuring the spectral content (e.g., wavelength) of one or more of the LED groups. In some embodiments, since all LEDs 602 and LED groups within a particular area of ​​wafer 102 may have similar wavelength emission, spectral content detection is a sampling inspection of pre-configured or selected LED groups.

[0087] Brightness measurements are synchronized with the energization pattern based on the timing data of the sequential energization pattern. For example, computing device 106 identifies and / or triggers a brightness measurement at one time within the LED timing window of an LED group. Computing device 106 receives one or more group brightness measurement signals from photodetector 116 and monitors brightness by comparing one or more group brightness measurement signals with one or more group brightness thresholds. The group brightness thresholds include one or more of the group lower brightness threshold 504 and / or group upper brightness threshold 506. Optionally, computing device 106 receives one or more spectral content measurement signals from spectrometer 132 and monitors spectral content by comparing one or more spectral content measurement signals with one or more spectral content or wavelength thresholds. The wavelength thresholds include one or more of the lower wavelength threshold and / or upper wavelength threshold. In some embodiments, the LED test system 100 measures and monitors the spectral content of a subset of LEDs 602 of an LED subset 202 being probed and / or an LED group. In some embodiments, the subset corresponds to one spectral content measurement for every "N" group luminance measurements. In some embodiments, the enterprise designates a set of LEDs 602 and / or LED groups on wafer 102 for spectral content measurement, for example, according to an LED identifier and / or LED group identifier, and the LED test system 100 limits the spectral content measurement to the designated LEDs 602 and / or LED groups (for example, spectral content measurement is performed on the LED groups corresponding to the designated LEDs 602 and / or designated LED groups).

[0088] In step 808, the LED test system 100 records the test results for each LED group based on the LED group identification time window 510 for each LED group. For example, the computing device 106 determines whether a portion of the group luminance curve 512 corresponding to each LED group remains within an acceptable range between the group lower luminance threshold 504 and the group upper luminance threshold 506. The data stored in the computing device 106 logically associates each LED group with a portion of the group luminance curve 512 corresponding to the LED group identification time window 510 and / or between two LED group identification boundary times 508. For example, data describing the energization pattern specifies one or more LED group identification boundary times 508 and / or one or more LED group identification time windows 510.

[0089] In some cases, the computing device 106 determines that the group luminance curve 512 remains within an acceptable range throughout the test, and records the pass or pass test result for each LED group. However, if the computing device 106 determines that one or more portions of the group luminance curve 512 are below the group lower luminance threshold 504 and / or above the group upper luminance threshold 506, the computing device 106 records the fail or fail test result for one or more LED groups corresponding to one or more portions of the group luminance curve 512. The computing device 106 determines one or more times when the group luminance curve 512 is outside an acceptable range, and uses data describing the energization pattern to identify one or more LED groups based on those one or more times.

[0090] In step 810, the LED test system 100 sequentially applies current to individual LEDs in one or more LED groups that have failed or unacceptable test results, and synchronously acquires brightness measurements. As described with respect to Figures 4 and 7, the computing device 106 performs individual LED tests by sequentially applying energizing pulses 402 to individual LEDs. The computing device 106 limits this test to LEDs 602 corresponding to one or more LED groups that have been identified as having failed or unacceptable test results.

[0091] The LED test system 100 sequentially applies energizing pulses 402 to LEDs 602 corresponding to one or more LED groups identified as having failed test results. Individual energizing pulses 402 energize individual LEDs 602 of the LED subset 202 being probed. In some embodiments, the consecutive energizing pulses of the energizing pattern are activated at least partially simultaneously. The LED test system 100 also monitors the luminance measurements of the individual tests. A computing device 106 receives one or more luminance measurement signals from a photodetector 116 and compares one or more luminance measurement signals to one or more individual luminance thresholds. The luminance thresholds include one or more of the lower luminance threshold 404 and / or upper luminance threshold 406. In some embodiments, the computing device 106 also receives one or more spectral content measurement signals from a spectrometer 132 and monitors spectral content by comparing one or more spectral content measurement signals to one or more spectral content or wavelength thresholds.

[0092] In stage 812, the LED test system 100 records the test results for each LED 602 ​​in the individual LED test. In some cases, the computing device 106 determines that the luminance curve 412 remains within an acceptable range throughout the test, and the computing device 106 records the pass or pass test result for each LED 602. However, if the computing device 106 determines that one or more portions of the luminance curve 412 are below the lower luminance threshold 404 and / or above the upper luminance threshold 406, the computing device 106 records the fail or fail test result for one or more LEDs 602 corresponding to one or more portions of the luminance curve 412. The computing device 106 determines one or more times when the luminance curve 412 is outside an acceptable range, and uses data describing the energization pattern to identify one or more LEDs 602 based on those one or more times.

[0093] In some embodiments, once group LED testing and / or individual LED testing is performed, the LED testing system 100 disconnects the probe pair 112 from the currently probing LED subset 202 and moves it to another (e.g., the next) LED subset 202 to be probed on the wafer 102. In some embodiments, the LED testing system 100 disconnects the probe pair 112 by moving the wafer chuck 104 away from the probe device 108. The LED testing system 100 moves the wafer chuck 104 laterally (e.g., in the plane of the surface of the wafer chuck 104 in contact with the wafer 102) so that the probe pair 112 and the optical guide 118 are aligned with the next LED subset 202 to be probed on the wafer 102. The LED testing system 100 connects the probe pair 112 to the next LED subset 202 to be probed by moving the wafer chuck 104 toward the probe device 108. The process then moves to stage 802, where the LED test system 100 connects to the next LED subset 202 of wafer 102 to be probed.

[0094] In short, the disclosed technology involves sequentially energizing a subset of LEDs to be probed on a wafer by applying a series of sequential energizing pulses synchronized with a luminance and / or spectral measurement timing window. Individual probe pairs are connected to individual LEDs. Individual energizing pulses energize individual LEDs among those being probed. In some embodiments, the consecutive energizing pulses of the pattern are activated at least partially simultaneously (e.g., overlapping in time). Some embodiments include a chuck holding a wafer containing the LEDs, a probe device including probe pairs connected to a subset of LEDs to be probed, and a stationary photodetector assembly for detecting the light emitted by all of the LED subsets being probed.

[0095] At least one technical advantage of the disclosed technology over the prior art is that the disclosed technology enables fast and reliable luminance testing before pulverization. Another technical advantage is that the speed and efficiency of luminance testing are increased compared to existing technologies for luminance testing on wafers and / or before pulverization. These technical advantages represent one or more technical advancements over the prior art approach.

[0096] Aspects of the subject matter described herein are described in the following numbered sections.

[0097] 1. In some embodiments, a computer implementation method comprises the steps of: connecting a plurality of probe pairs to a subset of a plurality of light-emitting diodes (LEDs) on a wafer; sequentially applying a plurality of energizing pulses through the plurality of probe pairs, wherein each of the plurality of energizing pulses energizes an individual of the subset of the plurality of LEDs, wherein a sequence of the plurality of energizing pulses is activated at least partially simultaneously; and synchronously detecting luminance measurements of one or more of the subset of the plurality of LEDs using a stationary photodetector assembly for detecting the light emitted by all of the subset of the plurality of LEDs.

[0098] 2. The method according to item 1, further comprising the step of recording test results for each LED of the subset of LEDs based on the luminance measurement values ​​and one or more luminance thresholds.

[0099] 3. The method according to item 1 or 2, wherein the photodetector assembly includes an optical guide that captures the light emitted by all of the subset of the plurality of LEDs and directs it to a single photodetector.

[0100] 4. The optical guide is the method described in any of items 1 to 3, comprising a bundle of optical fiber strands.

[0101] 5. The method according to any one of items 1 to 4, wherein the photodetector assembly includes an optical guide that captures the light emitted by all of the subset of the plurality of LEDs and directs it to a photodetector and a spectrometer.

[0102] 6. The method according to any one of items 1 to 5, wherein the consecutive energizing pulses among the plurality of energizing pulses are activated at least partially simultaneously by temporally overlapping at least a portion of the first time window of the first energizing pulse with at least a portion of the second time window of the second energizing pulse.

[0103] 7. The method according to any one of items 1 to 6, further comprising the step of detecting spectral measurements of one or more subsets of the plurality of LEDs using the spectrometer.

[0104] 8. The method according to any one of items 1 to 7, further comprising the steps of: disconnecting the plurality of probe pairs from the subset of the plurality of LEDs on the wafer; moving a wafer chuck based on LED location data of the plurality of probe pairs; and connecting the plurality of probe pairs to another subset of the plurality of LEDs.

[0105] 9. The method according to any one of items 1 to 8, wherein the wafer is a transparent wafer, and the light emitted by all of the subset of the plurality of LEDs is emitted through a transparent wafer chuck that holds the wafer.

[0106] 10. The method according to any one of items 1 to 9, wherein the plurality of LEDs are microLEDs with a size smaller than 100 micrometers.

[0107] 11. In some embodiments, a light-emitting diode (LED) test system for testing LEDs on a wafer, the LED test system comprising: a chuck for holding a wafer containing a plurality of LEDs; a probe device having a plurality of probe pairs connected to a plurality of LED subsets to be probed, wherein each of the probe pairs is connected to a particular of the LED subsets to be probed; a photodetector assembly stationary for detecting light emitted by all of the LED subsets to be probed; and at least one computing device for applying a plurality of energizing pulses, wherein each of the plurality of energizing pulses energizes a particular of the LED subsets to be probed, and a sequence of the plurality of energizing pulses is activated at least partially simultaneously.

[0108] 12. The LED test system according to item 11, wherein the at least one computing device further records the test results of each LED of the subset of LEDs based on the luminance measurement and one or more luminance thresholds.

[0109] 13. The LED test system according to item 11 or 12, wherein the photodetector assembly has an optical guide that captures the light emitted by all of the subset of the plurality of LEDs and directs it to a single photodetector.

[0110] 14. The optical guide is an LED test system as described in any of items 11 to 13, including a bundle of optical fiber strands.

[0111] 15. The LED test system according to any one of items 11 to 14, wherein the photodetector assembly has an optical guide that captures the light emitted by all of the subset of the plurality of LEDs and directs it to a photodetector and a spectrometer.

[0112] 16. The LED test system according to any one of items 11 to 15, wherein the wafer is a transparent wafer, and the light emitted by all of the subset of the plurality of LEDs is emitted through a transparent wafer chuck that holds the wafer.

[0113] 17. In some embodiments, one or more non-transient computer-readable media store program instructions causing one or more processors to perform a method that, when executed by one or more processors, includes the steps of: connecting a plurality of probe pairs to a subset of a plurality of light-emitting diodes (LEDs) on a wafer; sequentially applying a plurality of group energizing pulses through the plurality of probe pairs, wherein each of the plurality of group energizing pulses energizes an LED group comprising two or more LEDs from the subset of the plurality of LEDs, wherein consecutive group energizing pulses are activated at least partially simultaneously; and detecting one or more luminance measurements using a photodetector assembly stationary for detecting the light emitted by all of the subset of the plurality of LEDs.

[0114] 18. The method further comprises the step of recording the test results for each of the LED groups based on the luminance measurement and one or more group luminance thresholds, in one or more non-temporary computer-readable media as described in item 17.

[0115] 19. One or more non-temporary computer-readable media as described in item 17 or 18, further comprising the steps of: disconnecting the plurality of probe pairs from the subset of the plurality of LEDs on the wafer; moving a wafer chuck based on LED location data of the plurality of probe pairs; and connecting the plurality of probe pairs to another subset of the plurality of LEDs.

[0116] 20. One or more non-temporary computer-readable media according to any one of items 17 to 19, further comprising the steps of: determining, based on one or more luminance thresholds, that the luminance measurement of one or more LED groups is outside an acceptable range; and performing an individualized test of a set of LEDs corresponding to the one or more LED groups to identify an individual LED that caused the luminance measurement of one or more LED groups to be outside an acceptable range.

[0117] Any combination of any claim element described in any of the claims, and / or any combination of any element described herein, is included within the scope of the invention and the protection intended.

[0118] The descriptions of various embodiments are presented for illustrative purposes only and are not intended to be exhaustive or limitful to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0119] Aspects of this embodiment may be embodied as a system, method, or computer program product. Accordingly, aspects of this disclosure may take the form of a hardware embodiment as a whole, a software embodiment as a whole (including firmware, resident software, microcode, etc.), or a combination of software and hardware embodiments which may all be collectively referred to herein as “module,” “system,” or “computer.” In addition, any hardware and / or software technology, process, function, component, engine, module, or system described herein may be implemented as one circuit or a set of circuits. Furthermore, aspects of this disclosure may take the form of a computer program product embodied in one or more computer-readable media having embodied computer-readable program code.

[0120] Any combination of one or more computer-readable media may be used. A computer-readable media may be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium may be, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) would include electrical connections with one or more wires, portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In the context of this specification, a computer-readable storage medium may be any tangible medium that may contain or store programs for use by, or in connection with, an instruction execution system, apparatus, or device.

[0121] Aspects of this disclosure are described above with reference to flowcharts and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of this disclosure. It should be understood that each block in a flowchart and / or block diagram, and any combination of blocks in a flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a dedicated computer, or other programmable data processing device to generate a machine. When executed via the processor of the computer or other programmable data processing device, these instructions enable the implementation of the functions / operations specified in one or more blocks of the flowchart and / or block diagram. Such processors may, but are not limited to, general-purpose processors, dedicated processors, application-specific processors, or field-programmable gate arrays.

[0122] The flowcharts and block diagrams in the drawings illustrate the architecture, functionality, and operation of possible implementations of the systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. Note that in some alternative implementations, the functions shown in the blocks may be performed in a different order than shown in the diagram. For example, two blocks shown consecutively may actually be executed substantially simultaneously, or these blocks may be executed in reverse order depending on the functions involved. Note that each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, may be implemented by a dedicated hardware-based system or a combination of dedicated hardware and computer instructions that performs a specified function or operation.

[0123] While the foregoing descriptions relate to embodiments of the present disclosure, other and further embodiments of the present disclosure may be conceived without departing from their basic scope, the scope of which is determined by the following claims.

Claims

1. A method implemented by a computer, the computer implementation method is The stage of connecting multiple probe pairs to a subset of multiple light-emitting diodes (LEDs) on a wafer; The step of sequentially applying a plurality of energizing pulses through the plurality of probe pairs, wherein each of the plurality of energizing pulses energizes an individual of the subset of the plurality of LEDs, wherein consecutive of the plurality of energizing pulses are activated at least partially simultaneously; and A step of synchronously detecting luminance measurements of one or more of the subsets of the plurality of LEDs using a stationary photodetector assembly to detect the light emitted by all of the subsets of the plurality of LEDs. A computer-implemented method that includes [a specific feature / feature].

2. A step of recording the test results of each LED in the subset of multiple LEDs, based on the luminance measurement value and one or more luminance thresholds. A computer-implemented method according to claim 1, further comprising the above.

3. The computer-implemented method according to claim 1, wherein the photodetector assembly includes an optical guide that captures light emitted by all of the subset of the plurality of LEDs and directs it to a single photodetector.

4. The optical guide comprises a bundle of optical fiber strands, as described in claim 3, and is implemented by a computer.

5. The computer-implemented method according to claim 1, wherein the photodetector assembly includes an optical guide that captures light emitted by all of the subset of the plurality of LEDs and directs it to a photodetector and a spectrometer.

6. The computer-implemented method according to claim 5, wherein the consecutive energizing pulses among the plurality of energizing pulses are activated at least partially simultaneously by temporally overlapping at least a portion of the first time window of the first energizing pulse with at least a portion of the second time window of the second energizing pulse.

7. Steps to detect one or more spectral measurements of the subset of the plurality of LEDs using the spectrometer. A computer-implemented method according to claim 5, further comprising the above.

8. Steps include: cutting the plurality of probe pairs from the subset of the plurality of LEDs on the wafer; A step of moving the wafer chuck based on the LED location data of the plurality of probe pairs; and The step of connecting the plurality of probe pairs to another subset of the plurality of LEDs. A computer-implemented method according to claim 1, further comprising the above.

9. The computer-mounted method according to any one of claims 1 to 8, wherein the wafer is a transparent wafer, and the light emitted by all of the subset of the plurality of LEDs is emitted through a transparent wafer chuck that holds the wafer.

10. The computer-mounted method according to claim 9, wherein the plurality of LEDs are microLEDs with a size smaller than 100 micrometers.

11. A light-emitting diode (LED) test system for testing LEDs on a wafer, the LED test system is A chuck for holding a wafer containing multiple LEDs; A probe device having multiple probe pairs connected to a subset of LEDs to be probed, wherein each probe pair is connected to a specific LED subset to be probed; A photodetector assembly stationary for detecting the light emitted by all of the aforementioned LED subset being probed; and At least one computing device that applies a plurality of energizing pulses, wherein each individual of the plurality of energizing pulses energizes an individual of the subset of LEDs being probed, and a sequence of the plurality of energizing pulses activates at least partially simultaneously. A light-emitting diode (LED) test system equipped with [specific features / features].

12. The LED testing system according to claim 11, wherein the at least one computing device further records test results for each LED of the subset of LEDs based on luminance measurements and one or more luminance thresholds.

13. The LED test system according to claim 11, wherein the photodetector assembly has an optical guide that captures light emitted by all of the subset of the plurality of LEDs and directs it to a single photodetector.

14. The LED test system according to claim 13, wherein the optical guide includes a bundle of optical fiber strands.

15. The LED test system according to claim 11, wherein the photodetector assembly has an optical guide that captures the light emitted by all of the subset of the plurality of LEDs and directs it to a photodetector and a spectrometer.

16. The LED test system according to any one of claims 11 to 15, wherein the wafer is a transparent wafer, and the light emitted by all of the subset of the plurality of LEDs is emitted through a transparent wafer chuck that holds the wafer.

17. When executed by one or more processors, The stage of connecting multiple probe pairs to a subset of multiple light-emitting diodes (LEDs) on a wafer; The step of sequentially applying a plurality of group energizing pulses through the plurality of probe pairs, wherein each of the plurality of group energizing pulses energizes an LED group including two or more LEDs from the subset of the plurality of LEDs, wherein consecutive group energizing pulses are activated at least partially simultaneously; and A step of detecting one or more luminance measurements using a stationary photodetector assembly to detect the light emitted by all of the subset of the plurality of LEDs. A computer program that includes program instructions causing one or more processors to execute a method including the above.

18. The aforementioned method, A step of recording the test results for each of the LED groups based on the luminance measurement values ​​and one or more group luminance thresholds. Further including, The computer program according to claim 17.

19. The aforementioned method, Steps include: cutting the plurality of probe pairs from the subset of the plurality of LEDs on the wafer; A step of moving the wafer chuck based on the LED location data of the plurality of probe pairs; and The step of connecting the plurality of probe pairs to another subset of the plurality of LEDs. Further including, The computer program according to claim 17.

20. The aforementioned method, A step of determining, based on one or more luminance thresholds, that the luminance measurement values ​​of one or more LED groups are outside an acceptable range; and A step of performing individualized testing on a set of LEDs corresponding to one or more LED groups to identify individual LEDs that cause the luminance measurement values ​​of one or more LED groups to fall outside an acceptable range. Further including, A computer program according to any one of claims 17 to 19.

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