Rapid inspection of device under test

Abstract

An example method for testing a batch of individual devices of a device under test (DUT) uses a test tool having a probe, and includes testing a plurality of individual devices in sequence while the probe remains in physical contact with the DUT, by testing the plurality of individual devices in sequence while maintaining physical contact between the probe and the DUT, and testing the plurality of individual devices in sequence while maintaining physical contact between the probe and the DUT. Moving the probe and / or the DUT is accomplished in which, for each consecutive plurality of individual devices, the movement causes the probe (i) to electrically contact in parallel with a set of contacts associated with the plurality of individual devices to drive parallel electrical excitation of the plurality of individual devices, and then (ii) to disengage electrical contact with the set of contacts. Another example method electrically couples a power source to a probe at a first side of a DUT and a conductive surface at a second side of the DUT, and then controllably electrically energizes a plurality of individual devices by applying an alternating voltage to the probe relative to the conductive surface.

Description

BACKGROUND

[0001] Devices such as electronic, optoelectronic, electromechanical, and other types of devices can be detected and tested. One example test modality is to electrically excite a device, which imposes a voltage or current to contacts in electrical communication with the device. Typically, in this example, the device and the contacts are part of the same electrical circuit, and the imposed current / voltage is to drive the excitation of the device to produce various signals, such as emission values. These signals can then be monitored or sensed optically and / or electrically and recorded for analysis. A device subjected to such testing can be referred to as a device under test (DUT). SUMMARY

[0002] The disadvantages of the prior art are overcome and additional advantages are provided through the provision of a method for testing a batch of individual devices of a device under test (DUT). The method uses a test tool comprising a plurality of probes, and the method includes testing, in sequence, multiple ones of the batch of individual devices while the plurality of probes and the DUT remain in physical contact. The testing in sequence includes moving at least one of the plurality of probes or the DUT while maintaining physical contact between the plurality of probes and the DUT, wherein for each successive multiple of the multiple ones of the individual devices, the moving causes the plurality of probes to (i) and a set of contacts associated with the multiple individual devices to be in parallel electrical contact to drive parallel electrical excitation of the multiple individual devices, and then (ii) to disengage from electrical contact with the set of contacts associated with the multiple individual devices. The method additionally includes detecting signals emitted from each of the multiple ones of the individual devices based on the electrical excitation of the multiple individual devices.

[0003] In some embodiments, the individual devices are micro light emitting diode (micro-LED) devices.

[0004] In some embodiments, the moving moves the plurality of probes across the DUT at a continuous motion and a consistent speed.

[0005] In some embodiments, each probe of the plurality of probes includes a flexible probe tip that flexes when in physical contact with the DUT. The moving can move the plurality of probes across a surface of the DUT, the surface having variations in flatness corresponding to the batch of individual devices, and the plurality of probes can flex and maintain physical contact with the DUT while moving across the batch of individual devices.

[0006] In some embodiments, the driving imposes a voltage or a current on the set of contacts contacted by the plurality of probes to drive the parallel electrical excitation of the plurality of individual devices associated with the set of contacts via the plurality of probes. In some embodiments, each probe of the plurality of probes includes a respective individual electrical channel to selectively excite a respective individual device of the plurality of individual devices. Thus, a first individual electrical channel of a first probe of the plurality of probes can provide a different voltage or current level than a voltage or current level provided by a second individual electrical channel of a second probe of the plurality of probes.

[0007] In some embodiments, a probe of the plurality of probes is an electrically conductive plane that simultaneously and electrically contacts two or more contacts of the set of contacts associated with a plurality of individual devices of the multiplicity of individual devices and drives parallel electrical excitation of two or more individual devices of the plurality of individual devices associated with the two or more contacts for each plurality of individual devices of the multiplicity of individual devices.

[0008] In some embodiments, the method further includes synchronizing triggers of a detection system that performs the detecting with the movement, the synchronization selectively and sequentially enabling and disabling detection of the signal to coincide with sequential excitation of the multiplicity of individual devices.

[0009] In another aspect, a method for testing a batch of individual devices of a DUT is provided, and the method uses a test tool that includes a plurality of probes, and the method includes: electrically coupling a power source to (i) the plurality of probes located on a first side of the DUT and (ii) an electrically conductive surface located on a second side of the DUT; controllably electrically exciting a plurality of individual devices of the batch of individual devices by applying an alternating voltage to the plurality of probes relative to the electrically conductive surface, wherein a non-conductive material is disposed between (i) the electrically conductive surface or at least one of the plurality of probes and (ii) a respective electrical contact associated with the plurality of individual devices; and detecting a signal emitted from the plurality of individual devices based on the electrical excitation of the plurality of individual devices.

[0010] In some embodiments, the plurality of individual devices is a first plurality of the individual devices of the population of individual devices, and the plurality of probes electrically excite the first plurality of individual devices, and the method further comprises: moving at least one of the plurality of probes or the DUT, wherein the moving electrically excites a next plurality of individual devices of the population of individual devices; detecting signals emitted from the next plurality of individual devices based on the electrical excitation of the next plurality of individual devices; and repeating the moving and the detecting one or more times for a respective one or more additional pluralities of individual devices. In embodiments, the plurality of individual devices is a first plurality of the individual devices of the population of individual devices, the plurality of probes and the DUT are in physical contact, and the method further comprises: moving at least one of the plurality of probes or the DUT while maintaining the physical contact between the plurality of probes and the DUT, wherein the moving electrically excites a next plurality of individual devices of the population of individual devices; detecting signals emitted from the next plurality of individual devices based on the electrical excitation of the next plurality of individual devices; and repeating the moving and the detecting one or more times for each of one or more additional pluralities of individual devices.

[0011] In some embodiments, the electrically conductive surface is transparent, and the detecting is performed from the second side of the DUT based on the signals passing through the transparent electrically conductive surface.

[0012] In some embodiments, the DUT includes a non-conductive layer over the individual devices, and the plurality of probes includes flexible probe tips that flex when in physical contact with the non-conductive layer of the DUT.

[0013] Additional aspects of the disclosure relate to systems and computer program products configured to perform the methods described above and herein. The summary is not intended to specify every aspect, implementation, and / or embodiment of the present disclosure. Additional features and advantages will be set forth in the claims, descriptions, and / or drawings that follow. BRIEF DESCRIPTION OF DRAWINGS

[0014] The aspects described herein relate to what is specifically claimed below in the claims and are expressly incorporated herein by reference in their entirety. The foregoing and other objects, features and advantages of the disclosure will be apparent from the following detailed description, which, taken in Figure 1A An example of contact testing with flexible probes is depicted; Figure 1B An example probe configuration with multiple probes for multi-DUT electrical contact in accordance with aspects described herein is depicted; Figure 1CAn example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 2 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 2 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 3 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 4 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 5 Figure 6 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 7 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 8 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 9 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 10 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; Figure 11 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein; and Figure 12 An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein. DETAILED DESCRIPTION

[0015] An example probe configuration is depicted that has multiple probes with a single channel for excitation in accordance with aspects described herein.

[0016] ​One of several examples of such testing is electro-opto-electroluminescence for micro light emitting diode (LED) (also referred to as “micro-LED,” “micro-LED,” “mLED,” and “pLED”) display inspection. Many of the examples described herein are presented with reference to testing of micro-LEDs. Micro-LED testing is particularly useful for micro-LED display inspection. Micro-LED displays contain millions of micro-LEDs, and efficient testing thereof is a key step in enabling mass production and marketization of micro-LED displays.

[0017] Aspects described herein enable simultaneous testing using an array of probes. Simultaneous (or “parallel”) testing according to aspects described herein can yield superior, consistent, and repeatable results. Examples include parallel electrical interactions (i.e., simultaneous for multiple devices) to efficiently energize an array of devices for inspection. Although features described herein are presented with specific reference to micro-LEDs, one of ordinary skill in the art will appreciate that features described herein can be used when testing / inspecting various devices and types of samples, including electromechanical, electro-optical, and other types of devices / samples, and will further appreciate that aspects can be applicable to single element testing and multi-element testing, e.g., device arrays.

[0018] In some embodiments, a tool is provided that operates as a series of probes imposing voltage or current to contact points to energize a plurality of corresponding devices (e.g., electronic, optoelectronic, or electromechanical DUTs, by way of example), and then optically and / or electrically measuring and monitoring signals produced by the energized plurality of devices. The probes make electrical contact in parallel (i.e., simultaneously) at multiple locations.

[0019] In contact testing, test probes are placed in physical contact with contact points and are applied with some sensible level of force. The probes can have appropriate flexibility, essentially being “soft touch” / flexible, such that the probes can be applied with or without monitoring and adjustment (as active feedback) to adjust their flexing or bending, e.g., similar to how the brush tip of a paintbrush would flex or bend when applied to a surface with a certain force. The flexibility of the probes allows for rapid testing of multiple devices under test (DUTs). For example, in some embodiments, there can be relative movement between the array of probes and the DUTs, e.g., movement in a horizontal direction relative to the DUT surface, without damaging the probes and DUTs. This enables rapid testing of a large number of DUTs.

[0020] Figure 1A Examples of contact testing with flexible probes are depicted. Figure 1AA probe 112 is shown. The probe 112 is used to test a DUT 102, which includes a plurality of individual devices 104 (which can individually be referred to as a device under test or DUT), such as micro-LEDs. Figure 1A At least a portion of the probe 112 is flexible, such as the probe 112 having a flexible tip 116. Electrical contact is established between the individual DUT 104 and the probe 112 (and particularly the flexible tip 116 of the probe), and can be established sequentially, such as through relative movement in a horizontal direction (such as movement of the probe 112 relative to a surface of the DUT 102) between the probe 112 (such as the probe 112 as it scans a portion of the DUT) and the individual DUT 104, for example, to drive excitation of the individual DUT 104.

[0021] The methods and devices discussed herein enable repeated, simultaneous, flexible electrical contact and interaction to excite multiple devices under test with functional efficacy, without damaging the probes or devices, and without the need for and / or taking any measurements / monitoring of active feedback (but allowing such active feedback if desired). In some examples, this is provided via appropriate mechanical properties, such that multiple probes can repeatedly appropriately interact with electrical contacts of devices without damaging the probes or device structures. The flexibility of the probes can be selected and imparted to suit relatively larger lateral devices with variations in flatness. Thus, physical / electrical contact between the probes and the DUTs can be maintained in testing of multiple devices (via electrical contact pads of / those associated with those devices) even though variations in flatness can be present on the DUTs. Such flexibility can also extend the life of the probes, as the flexibility limits or eliminates damage to the probes.

[0022] The probe configuration can vary from DUT to DUT. When considering a probe configuration of multiple probes, such as an array of probes arranged in a row of probes (a "probe array") in some examples, a flexible probe array can be manufactured with appropriate spacing and geometry so as to provide an unobstructed view of the DUT at the highest power of an optical microscope when needed in excitation of the DUT. Silicon-based and other microfabrication techniques, such as 3D printing, can provide everything needed to manufacture a probe array with appropriate flexibility, mechanical properties, geometry, and electrical pattern to provide the necessary electrical inputs and outputs according to the specific parameters of the DUT to achieve the desired excitation.

[0023] Figure 1B An example probe configuration having multiple probes for multi-DUT electrical contact is depicted in accordance with aspects described herein. Figure 1Bprobe configuration for testing a device under test 102, which includes a plurality of individual devices 104, such as micro-LEDs. In this example, the plurality of individual devices 104 are patterned / arranged into an array. A probe support structure / housing 106 (also depicted in Figure 1A FIG. 1) is provided to support / contain the plurality of individual probes 112 as part of a testing apparatus / tool. Portion 110 shows more detail of a subset of the array of probes, which are each typically extended as an arm from the support structure / housing 106.

[0024] The probes 112 have a base portion 114 and a tip portion 116. Here, the tip portion 116 forms a tip (e.g., a pyramid, a triangle, or a cone, or a sphere). In some embodiments, the tip extends below the rest of the probe and makes electrical contact with the sample. In other embodiments, each probe does not have a tip (i.e., a pyramid, a triangle, a cone, or a sphere, etc.), but rather has a flat / straight surface that makes contact with the sample. Probes of the latter design (e.g., without a tip) can sometimes provide advantages, as testing can be accomplished with less pressure imposed from the probe tip onto the DUT. In turn, this can minimize or eliminate damage to the DUT, extend the life of the probes, and enable faster scan speeds (in the context of the present disclosure, “scan” refers to the act of sweeping the probes across the individual devices of the DUT while maintaining physical (in some embodiments) contact between the probes and the DUT as the individual devices are tested in successive batches with simultaneous excitation of the individual devices).

[0025] Each individual probe in the array of probes can have a respective single voltage / current channel that enables selective excitation (or not) of different DUTs with different / unique values of voltage / current as desired / independent (i.e., each channel can provide the same or different voltage / current than any other single channel). Each individual probe can provide respective measurements of different DUTs independently via the single channel of the probe.

[0026] Figure 1C An example probe configuration of a plurality of probes 151 having a single channel (152; Figure 1C only some of which are labeled in FIG. 1) is depicted. The cantilever length is denoted at 150. Example probe shapes are shown by 154 (flat / straight end probes 154a with a probe width of 150 pm (micrometers) and a pitch of 100 pm, or tip probes 154b with a pitch between the tips of the pyramids 156 of 40 pm). In this example, the cantilever length is 200 pm. These are provided as non-limiting examples, as the probe dimensions, pitch, etc. can be varied as desired (e.g., according to the particular characteristics of the DUT).

[0027] Figure 2 Another example probe configuration with tips for contacting multiple DUT electrical contacts is depicted. This configuration is related to... Figure 1B The configurations are basically similar, except that the end portion 216 of probe 212 has a tip 218 extending (downward in this example) from the underside of probe 212 toward each device 204.

[0028] Another embodiment of the probe structure includes a conductive plane instead of a single row of probes, with each probe contacting a single individual device at a time. For example, the length of the conductive plane can be... Figure 1A , Figure 1B , Figure 1C and / or Figure 2 The probes are identical, but their width W is, for example, the same as... Figure 1A , Figure 1B , Figure 2 The entire row of probes depicted in the image has the same width. Figure 3 The structure with a conductive plane 312 for testing device 304 is depicted. The dimensions (W, length L) of the conductive plane can vary and be changed according to a specific DUT. Figure 3 The advantage of this probe configuration is that it can stimulate a large number of LED structures (or other devices / samples) without changing the probe card design and wafer design, where the sample (e.g., LED) pitch and / or width can be smaller than the minimum possible width and pitch achievable by the individual probes in the probe array.

[0029] In yet another implementation, the probe device can be similar to Figure 3 The conductive plane method simply divides the plane into different parts. Figure 4 This example depicts a probe array structure 401 with separated conductive planes 412, with spaces 460 between them. The spaces (gap) 460 between the planes 412 can correspond to gaps 410 in the individual devices 404 under test. The width of each plane 412 and the portion 460 between them can be varied. The gaps 460 between the planes 412 allow for better matching of the individual device patterns on the DUT and reduce obstruction to observation. The separated planes provide greater probe flexibility and are less affected by uneven surface flatness. The gaps 460 can mitigate the effects of unintended bumps and inconsistent textures on the surface of the DUT, as the planes 412 can avoid potential bumps or other obstacles that might be present on the DUT in the gaps 410 between the devices 404, the positions of which correspond to the gaps 460. A consistent probe structure achieves more consistent electrical contact and thus more repeatable readouts from this excitation.

[0030] In some cases, the LED's solder pads / contacts are covered by a non-conductive layer, thus preventing the solder pads / contacts from providing electrical access to the probe array. In this situation, an AC high-voltage source can be connected to the probe array and a conductive surface placed under the DUT. In these cases, electrical excitation can be achieved by applying an AC voltage to the probe array in contact with one side of the LED's non-conductive layer and a conductive plate in contact with the other side of the LED. The probe array and conductive plate form a capacitor that can store and release charge under AC power. The AC voltage drives the recombination of electrons and holes (i.e., current) within the LED, causing the LED to emit light. Conventional methods using capacitive excitation mechanisms use only a single probe. According to the aspects described herein, the method can simultaneously excite multiple samples using a probe array, and soft probes can excite the LED without damaging the non-conductive layer surrounding the LED. Therefore, capacitively driven testing according to the aspects described herein can utilize flexible probes (instead of needles or conventional probe cards) and can drive multiple devices for simultaneous testing. It should be noted that specific parameters of capacitive excitation (such as voltage and frequency) can depend on the design of the sample itself (e.g., the area of ​​similar contact pads, the thickness of non-conductive layers, the structure of the sample, and / or the characteristics of the probe card itself, as examples).

[0031] Figure 5 A schematic diagram is depicted showing the electrical excitation of a DUT 502 using a probe array 507 connected to one of the poles of a current / voltage supply 510, and the DUT's common ground 562 also connected to the current / voltage supply 510. This configuration is suitable for testing both contact and non-contact DUTs.

[0032] Overall, Figure 5 The possibilities of contact and non-contact electrical excitation are described. Figure 6 Depicts the use of a device connected to a current / voltage power supply (such as...) Figure 5 The diagram illustrates an example of non-contact electro-excitation of a DUT 602 with various devices 604, achieved by a probe array of probes 612 at the pole (shown) and a conductive plate 611 placed on the DUT 602 and a non-conductive substrate 607. The DUT 602 is connected to the other pole of a current / voltage power supply device. In this case, the accessibility / inaccessibility of the contact pads defines which method (contact / non-contact) is used; for example, 606 is a conductive pad, while 608 is an inaccessible conductive pad. Therefore, applying an AC voltage via the probes or conductive pads can form an excitation capacitor between them to drive the LED.

[0033] In some implementations, the conductive plate may be transparent to enable monitoring and detection of signals generated by the DUT (e.g., each individual device of the DUT) from below.

[0034] Figure 7 A schematic diagram of the photoelectronic device under test 702 is shown when a signal is detected from the bottom (the lower side of DUT 702).

[0035] In the case of the optoelectronic device under test (e.g., a display based on micro-LEDs), the micro-LEDs of the DUT emit light due to, for example, electroluminescence, and for each micro-LED, the emitted light is measured.

[0036] The corresponding measurement value of the light emitted from each microLED can be obtained, serving as an indicator of the individual performance of each such microLED. Accurate measurement becomes challenging if the probe array obstructs the optical device for measuring the emitted light. When the probe contact point is with the individual device under test (… Figure 7 When the miniature LED 704 is on the same side of the test sample (DUT 702), the probe tip that contacts at the contact point can be configured with an appropriate geometry so that the light emitted from the device under test is not blocked or is substantially unaffected.

[0037] For example, the emission signal or other response of the DUT in response to its excitation can be optically observed from above, below, and / or the other side of the excitation. In some embodiments, a flat, transparent surface (such as the surface where a probe array is placed or coupled) is used for mechanical support and strength or other purposes, and also allows emitted light to pass through the surface for detection. The surface can also allow excitation using a tool that can be driven by illuminating the wafer or device structure through the transparent surface, and then measuring the photovoltage or photocurrent generated as a response. For example, this could be a method used, for instance, in testing solar cells, where a voltage is generated using light or other solar energy excitation.

[0038] Still referencing Figure 7 When the probe 712 is pulled across / across the DUT 702, for example to scan the DUT, the probe 712 drive mechanism 704 is activated. This is achieved by moving the probe (from right to left in this example), moving the DUT 702 (from left to right in this example), or a combination of both. When the probe and DUT are moved relative to each other, the probe 712 can maintain continuous physical contact with the DUT, or the probe can contact the sample 704, then disengage from the sample, and then contact the next sample 704. Figure 7In (a), probe 712 is in contact with LED 704a (and / or the contact pads associated with 704a) to drive excitation of 704a and emission of light therefrom, which can be measured from below DUT 702 with an optical detector (as one example). Note that the probe 712 can be pulled continuously across the contacts of 704a, which causes 704a to illuminate for an amount of time. When the probe is pulled across the contacts of 704a, the probe disengages from contact with the contacts, as shown in (b). The distal end of probe 712 is shown in the space between 704a and the next sample 704b. The probe 712 can be further pulled so that in (c), the probe distal end is in contact with LED 704b (and / or the contact pads associated with 704a) to drive excitation of 704b and emission of light therefrom, which can be measured as described above. This is repeated for an entire row of samples. At the same time, if desired, the movement of the probes relative to the DUT can be continuous and uniform in speed. In some embodiments, the height of the probe structure / housing above the DUT 702 is maintained at a constant height, and the flexibility of the probes facilitates dragging / scanning of the distal ends of the probes across the DUT, including its various samples.

[0039] An example excitation and detection method is as follows: - Lowering the probe array toward the DUT until the probes reach and make physical and electrical contact with a matching row of pads / contacts on the DUT associated with a first plurality of samples; - In some examples where the DUT contains LED devices as the plurality of samples, the devices emit light as a result of being excited by the probes; - While the probe array is in contact with the DUT, performing relative continuous movement between the probe array and the DUT (e.g., in a horizontal direction, without requiring movement in a vertical direction), and the probe array reaches and contacts a following plurality of matching pads / contacts; - In the example, a trigger is synchronized with continuous movement. This trigger is transmitted to the optical / electrical inspection system at fixed intervals (associated with multiple subsequently energized devices) to measure signals from / acquire images of the energized devices (e.g., LEDs), synchronized with the device's position. In other words, while an array of probes is energizing multiple LEDs, a trigger can be sent to the inspection system to detect signals from said multiple LEDs. This detection can continue for a certain amount of time (or until the trigger is released). Simultaneously, the probes eventually stop energizing said multiple LEDs (based on the movement of the probes and / or the DUT), and the inspection system waits for the next trigger, such as a trigger sent to the inspection system based on contact between the probes and said multiple subsequent LEDs, to activate said multiple subsequent LEDs. In this way, signal detection can be selectively and sequentially enabled / disabled to correspond to the sequential energization of multiple sets of devices on the DUT.

[0040] Therefore, when the probe array reaches the next set of contacts, they excite the next set of corresponding LEDs, and the excitation is detected by the detection system.

[0041] - The above process involves multiple iterations for different DUT regions / each device of the DUT.

[0042] Figure 8 A schematic diagram of the optoelectronic device under test is depicted when the emitted signal is detected from above the device. Figure 8 and Figure 7 The same applies, except that an emission was detected above device 804. For example... Figure 7 Similarly, there is relative movement between probe 812 and DUT 802, for example, scanning probe 812 above DUT 802 and / or scanning DUT 802 below probe 812. In any case, the probe sequentially (i) contacts the contacts of device 804a to activate device 804a, (ii) disengages from the contacts of device 804a, and then (iii) contacts the next contact of the next device 804b to activate the next device 804b. This process may be repeated once or multiple times for other devices under test.

[0043] The advantage of the implementation schemes of the apparatus / methods discussed in this paper is that they can achieve test speeds significantly faster than conventional methods. Continuous movement using continuous physical contact can provide much greater speeds than conventional methods using probe cards, which bring probes into contact with contact pads, energize the sample, lift the probes from the sample / DUT, move the probes horizontally, stop, approach the next contact, and then energize again. For example, acceleration and deceleration in this process can increase the time required to inspect the DUT.

[0044] A probe array support structure is also provided. Electrical communication between the probe array and the voltage / current source can be achieved through a highly conductive spring structure. One end of the spring firmly secures the probe array, while the other end is connected to the power supply. The spring structure ensures a robust mechanical hold of the probe array and constant electrical communication between the probe array and the power supply. The spring can have a large accessible conductive surface area and strong mechanical properties, thus facilitating easier electrical connections.

[0045] Figure 9 A schematic diagram of a probe support housing / structure is depicted, using a spring structure 904 to hold a probe 902 in place. The spring structure 904 is conductive and electrically connected to the probe 902, allowing electrical signals to be transmitted between the probe 902 and another part of the probe. In this way, the spring structure can serve (at least) a dual function: holding the probe 902 and providing electrical conduction to the array of probes 902. 906 is a device (e.g., a screw and nut) for holding the spring structure 904 in place. The flexibility of the spring facilitates easy replacement of the probes, if needed. In some embodiments, automatic replacement of the probe array can be achieved; the relatively small footprint of the probe array and probe array holder (904) described above allows a designated robot to remove the probe array holder and automatically replace it with a new probe array and probe array holder in the event of a damaged probe array.

[0046] This document has described apparatus and related methods / processes. For example, a process for testing a sample array comprising individual samples is provided, and said process may be performed using a test tool including test probes. In one or more examples, the process may be performed by a processor or processing circuitry of one or more computers / computer systems (such as those described herein, e.g., of the test tool or a computer system communicating with the test tool).

[0047] Figure 10 and Figure 11 An example method for testing a batch of various devices of a device under test (DUT) is described. The example method uses a test tool comprising multiple probes. In the example, the various devices are miniature light-emitting diodes (miniature LEDs).

[0048] Initial reference Figure 10The method tests a plurality of individual devices in the batch of individual devices in sequence. This is done while the plurality of probes remain in physical contact with the DUT. The testing in sequence includes moving (1002) at least one of (i) the plurality of probes or (ii) the DUT while maintaining physical contact between the plurality of probes and the DUT. The moving causes (1004) the plurality of probes to make parallel electrical contact with a set of contacts associated with the plurality of individual devices to drive parallel electrical excitation of the plurality of individual devices. The method detects (1006) signals emitted from the plurality of individual devices based on the electrical excitation of the plurality of individual devices, and then the moving causes (1008) the plurality of probes to disengage electrical contact with the set of contacts associated with the plurality of individual devices.

[0049] The continued movement of the probes and / or the DUT can result in repeating this process for a subsequent plurality of individual devices, where parallel electrical contact is established to excite the subsequent plurality of individual devices and signals emitted from the subsequent plurality of individual devices are detected, such that the process detects signals emitted from each of the plurality of individual devices in the plurality of pluralities of individual devices based on the electrical excitation of the plurality of individual devices. When the probes contact the DUT and one or both are moved, the repeated excitation and detection can be repeated one or more times until there are no longer subsequent pluralities of individual devices. This can involve, for example, reaching the end of a "scan" of the DUT to test a corresponding number of rows of devices. Then, in some embodiments, the probes and / or the DUT can be reset to a different position, and Figure 10 The testing in sequence can be repeated for, for example, a subsequent plurality of pluralities of individual devices.

[0050] In embodiments, each probe of the plurality of probes includes a flexible probe tip that flexes when in physical contact with the DUT.

[0051] In embodiments, the moving can move the plurality of probes across a surface of the DUT, the surface having variations in flatness corresponding to the batch of individual devices. The plurality of probes can flex and maintain physical contact with the DUT while moving across the batch of individual devices.

[0052] In embodiments, the moving moves the plurality of probes across the DUT with continuous motion and a consistent speed.

[0053] The driving of the parallel excitation can impose a voltage or a current on a set of contacts contacted by the plurality of probes to drive the parallel electrical excitation of the plurality of individual devices associated with the set of contacts via the plurality of probes.

[0054] Each of the plurality of probes can include a respective individual electrical channel to selectively energize a respective individual device of the plurality of individual devices. Thus, for example, a first individual electrical channel of a first probe of the plurality of probes can provide a different voltage or current level than a voltage or current level provided by a second individual electrical channel of a second probe of the plurality of probes.

[0055] In some embodiments, a probe of the plurality of probes is an electrically conductive plane that simultaneously and electrically contacts two or more contacts of the set of contacts associated with the plurality of individual devices and drives parallel electrical energization of two or more individual devices of the plurality of individual devices associated with the two or more contacts for each of a plurality of individual devices of the plurality of individual devices. The plurality of probes can include a set of such electrically conductive planes, where each such plane energizes a corresponding one or more devices for each successive plurality of individual devices.

[0056] In embodiments, the method can also synchronize a trigger of a detection system that performs the detecting with the moving. The synchronization can selectively and sequentially enable and disable detection of the signal to coincide with sequential energization of the plurality of individual devices. Thus, the synchronization can be used to control the detection system to detect emitted signals when needed, for example, after each successive energization of a plurality of devices. For example, between energizations, the detection by the system can be disabled.

[0057] Figure 11 Another example method is depicted for testing a set of individual devices of a DUT using a test tool having a plurality of probes. The method electrically couples (1102) a power source to (i) the plurality of probes located on a first side of the DUT and (ii) an electrically conductive surface located on a second side of the DUT. In embodiments, a non-conductive material is disposed between (i) the electrically conductive surface or at least one of the plurality of probes and (ii) a respective electrical contact associated with the plurality of individual devices. An example of such a material is a layer of non-conductive material. The method then controllably electrically energizes (1104) a plurality of individual devices of the set of individual devices by applying an alternating voltage to the plurality of probes relative to the electrically conductive surface and detects (1106) a signal emitted from the plurality of individual devices based on the electrical energization of the plurality of individual devices.

[0058] In embodiments, and similar to embodiments of method 10, this can be repeated for multiple individual devices. Thus, in embodiments, the multiple individual devices are a first plurality of the individual devices of the batch of individual devices and the multiple probes electrically stimulate the first plurality of individual devices, and the method further comprises: (a) moving at least one of the multiple probes or the DUT, wherein the moving electrically stimulates a next plurality of individual devices of the batch of individual devices; (b) detecting signals emitted from the next plurality of individual devices based on the electrical stimulation of the next plurality of individual devices; and (c) repeating the moving and the detecting one or more times for a respective one or more additional pluralities of individual devices.

[0059] In embodiments, Figure 11 The process of method 12 implements a capacitive-based test of individual devices. Thus, the test can be completed regardless of whether there is physical contact between the probes and the DUT or its individual devices. In particular embodiments that implement a sequential test, the multiple probes and the DUT are in physical contact, and the method further comprises: (a) moving at least one of the multiple probes or the DUT while maintaining the physical contact between the multiple probes and the DUT, wherein the moving electrically stimulates a next plurality of individual devices of the batch of individual devices; (b) detecting signals emitted from the next plurality of individual devices based on the electrical stimulation of the next plurality of individual devices; and (c) repeating the moving and the detecting one or more times for each of one or more additional pluralities of individual devices.

[0060] In embodiments, the electrically conductive surface is transparent, and the detecting is performed from the second side of the DUT based on the signals passing through the transparent electrically conductive surface.

[0061] In embodiments, the DUT includes a non-conductive layer over the individual devices, and the multiple probes include flexible probe tips that flex when in physical contact with the non-conductive layer of the DUT.

[0062] In some examples, a method or aspects thereof can be performed by one or more computer systems, e.g., a computer system controlling an apparatus / tool including an array of probes. For example, the control can control movement of the tool, the DUT, and / or components of each. The computer system can be incorporated with / provided as part of the tool, or can communicate with the tool through one or more communication links, which can be any wired or wireless communication links configured for digital / data communication. In some examples, the computer system can be remote from the tool. Thus, processes described herein can be performed by one or more computer systems individually or collectively. A computer system can also be referred to as a data processing apparatus / system, a computing apparatus / system / node, or simply a computer. A computer system can be based on one or more of various system architectures and / or instruction set architectures, such as, for example, system architectures and / or instruction set architectures provided by Intel Corporation (Santa Clara, California, USA) or ARM Holdings plc (Cambridge, England, United Kingdom).

[0063] Figure 12 The computer system 1200 is shown in communication with an external device 1212. The computer system 1200 includes one or more processors 1202, such as a central processing unit (CPU), for example. The processor can include functional elements that use in the execution of instructions such as to fetch program instructions from a location in a cache or main memory, decode program instructions, and execute program instructions, access memory to perform instructions, and write results of executed instructions. The processor 1202 can also include registers used by one or more functional elements. The computer system 1200 also includes a memory 1204, input / output (I / O) devices 1208, and I / O interfaces 1210, which can be coupled via one or more buses and / or other connections to the processor 1202 and to each other. Bus connections represent one or more of several types of bus structures including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA), Micro Channel Architecture (MCA), Enhanced ISA (EISA), Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnect (PCI).

[0064] Memory 1204 can be or include a main memory or system memory (e.g., random access memory) used in the execution of program instructions by the processor(s) 1202, storage devices such as, for example, a hard disk drive, flash media, or optical media, and / or, for example, cache memory. Memory 1204 can include, for example, a cache (such as a shared cache) that can be coupled to local caches (examples include LI cache, L2 cache, etc.) of the processor(s) 1202. Additionally, memory 1204 can be or include at least one computer program product having a set (e.g., at least one) of program

[0065] Memory 1204 can store operating system 1205 and other computer programs 1206, such as one or more computer programs / applications that execute to perform aspects described herein. In particular, the programs / applications can include computer-readable program instructions that can be configured to carry out the functions of embodiments of aspects described herein.

[0066] Examples of I / O devices 1208 include, but are not limited to, microphones, speakers, global positioning system (GPS) devices, cameras, lights, accelerometers, gyroscopes, magnetometers, sensor devices configured to sense light, proximity, heart rate, body and / or environmental temperature, blood pressure, and / or skin resistance, and activity monitors. As shown, the I / O devices can be incorporated into the computer system, although in some embodiments the I / O devices can be considered external devices (1212) coupled to the computer system through one or more I / O interfaces 1210.

[0067] Computer system 1200 can communicate with one or more external devices 1212 via one or more I / O interfaces 1210. Example external devices include keyboards, pointing devices, display devices, and / or any other device that enables a user to interact with computer system 1200. Other example external devices include any device (s) that enables computer system 1200 to communicate with one or more other computing systems or peripheral devices such as a printer. A network interface / adaptor is an example I / O interface that enables computer system 1200 to communicate with one or more networks such as a local area network (LAN), a general wide area network (WAN), and / or a public network (e.g., the Internet) to provide communication with other computing devices or systems, storage devices, etc. Ethernet-based (such as Wi-Fi) interfaces and Bluetooth® adaptors are just examples of currently available types of network adaptors used in computer systems (BLUETOOTH is a registered trademark of Bluetooth SIG, Inc. (Kirkland, Washington, U.S.A.).

[0068] Communication between I / O interface 1210 and external device 1212 can be over wired and / or wireless communication links 1211, such as wired or wireless connections based on Ethernet. Example wireless connections include cellular, Wi-Fi, Bluetooth®, proximity-based, near-field, or other types of wireless connections. More generally, communication links 1211 can be any suitable wireless and / or wired communication links for transferring data.

[0069] Particular external devices 1212 can include one or more data storage devices, which can store one or more programs, one or more computer-readable program instructions, and / or data, etc. Computer system 1200 can include and / or be coupled to and communicate with (e.g., as an external device of the computer system) removable / non-removable, volatile / non-volatile computer system storage media. For example, it can include and / or be coupled to a non-removable, non-volatile magnetic media (typically called a "hard drive"), a magnetic disk drive for reading and writing removable, non-volatile magnetic disks (e.g., "floppy disks"), and / or an optical disk drive for reading and / or writing removable, non-volatile optical disks (such as CD-ROMs, DVD-ROMs or other optical media).

[0070] Computer system 1200 can be operational with numerous other general purpose or special purpose computing system environments or configurations. Computer system 1200 can be any available form of a general purpose or special purpose computing system environment having computer readable program code, memory, and / or storage. Computer system 1200 can be operational with contemplating a computer system having a client-server relationship, a multiprocessor system including multiple processing units, or some other configuration, or combinations of the foregoing. Computer system 1200 can be

[0071] Aspects of the application can be a system, a method, and / or a computer program product, any or all of which can be configured to perform or facilitate the aspects described herein. In some embodiments, aspects of the application can take the form of a computer program product which can be embodied in a computer readable medium. The computer readable medium can be a tangible storage medium / anon-transitory computer readable medium that has stored thereon computer readable program code / instructions. Example computer readable media include, but are not limited to, electronic, magnetic, optical, or semiconductor storages systems, or any combination of the foregoing. Example embodiments of the computer readable medium include a hard disk, a floppy disk, a RAM, a ROM, an erasable programmable ROM (e.g., EPROM or EEPROM), flash memory, a portable computer disk drive (e.g., a CD-ROM or a DVD), an optical storage device, a magnetic storage device, or any combination of the foregoing. The computer readable medium can be read by a processor, processing unit, or the like to obtain data (e.g., instructions) from the medium for execution. In a particular example, the computer program product is or includes one or more computer readable media having stored thereon computer readable program code to provide and facilitate one or more aspects described herein.

[0072] As described above, program instructions included or stored in a computer readable medium can be obtained by any of various suitable means, such as by a processor of a computer system, to cause a computer system to perform and operate in a particular manner. Such program instructions can be written in any of a number of programming languages, or compiled from a code written in any of a number of programming languages, to be used by any of a number of computer systems. In some embodiments, such programming languages include object-oriented and / or procedural programming languages, such as C, C++, C#, Java, etc.

[0073] Program code can include one or more program instructions obtained from any of various sources, such as a computer system, a memory device, a software product, etc. Program code can be obtained by a computer system from one or more computer program products, which can be tangibly embodied in a computer readable medium. A computer program product can be a computer program that is downloaded from a network, such as the Internet, or a computer program that is stored on a computer readable medium, such as a floppy disk, a CD-ROM, a DVD, a memory stick, etc. Program code can be obtained by a computer system from one or more computer program products, which can be tangibly embodied in a computer readable medium. A computer program product can be a computer program that is downloaded from a network, such as the Internet, or a computer program that is stored on a computer readable medium, such as a floppy disk, a CD-ROM, a DVD, a memory stick, etc.

[0074] Although various examples are provided, variations can be made in light of the above teachings without departing from the spirit of the claimed aspects.

[0075] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0076] The corresponding structure, material, acts, and equivalents of all means or step plus function elements (if any) described herein are intended to include any structure, material, or act for performing the function in combination with other claimed The description of one or more embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the form of the disclosure to the precise embodiment disclosed. Many modifications and variations will be apparent to those skilled in the art. The described embodiments were chosen in order to better illustrate various aspects and features of the disclosure and to enable others skilled in the art to understand various implementations with various modifications as are suited to the particular use contemplated.

Claims

1. A method for testing a batch of devices of a device under test (DUT), the method using a test tool comprising a plurality of probes, the method comprising: While maintaining physical contact between the multiple probes and the DUT, multiple individual devices of the batch of devices are tested sequentially, the sequential testing including: While maintaining physical contact between the plurality of probes and the DUT, at least one of the plurality of probes or the DUT is moved, wherein for each successive plurality of the plurality of individual devices, the movement causes the plurality of probes to (i) make parallel electrical contact with a set of contacts associated with the plurality of individual devices to drive parallel electrical excitation of the plurality of individual devices, and then (ii) disengage from the electrical contact with the set of contacts associated with the plurality of individual devices; and Signals emitted from each of the plurality of devices are detected based on the electrical excitation of the plurality of devices.

2. The method of claim 1, wherein each of the plurality of probes includes a flexible probe end that flexes when in physical contact with the DUT.

3. The method of claim 2, wherein the movement causes the plurality of probes to move across the surface of the DUT, the surface having a flatness variation corresponding to the batch of devices, wherein the plurality of probes flex and maintain physical contact with the DUT while moving across the batch of devices.

4. The method of claim 1, wherein the drive applies voltage or current to the set of contacts contacted by the plurality of probes via the plurality of probes to drive the parallel electrical excitation of the plurality of individual devices associated with the set of contacts.

5. The method of claim 4, wherein each of the plurality of probes includes a corresponding electrical channel to selectively excite a corresponding device among the plurality of devices.

6. The method of claim 5, wherein the first electrical channels of the first probe of the plurality of probes provide a voltage or current level different from the voltage or current level provided by the second electrical channels of the second probe of the plurality of probes.

7. The method of claim 1, wherein the probes of the plurality of probes are conductive planes, and for each of the plurality of individual devices, the conductive planes simultaneously make electrical contact with two or more contacts of the set of contacts associated with the plurality of individual devices, and drive parallel electrical excitation of the two or more individual devices associated with the two or more contacts.

8. The method of claim 1, further comprising synchronizing a trigger of the detection system performing the detection with the movement, the synchronization selectively and sequentially enabling and disabling the detection of the signal to conform to the sequential excitation of the plurality of individual devices.

9. The method of claim 1, wherein the movement causes the plurality of probes to move across the DUT in a continuous motion and at a consistent speed.

10. The method of claim 1, wherein each of the devices is a micro light-emitting diode (micro LED) device.

11. A method for testing a batch of devices of a device under test (DUT), the method using a test tool comprising a plurality of probes, the method comprising: Electrically couple the power supply to (i) the plurality of probes located on the first side of the DUT and (ii) the conductive surface located on the second side of the DUT; Multiple devices in a batch of devices are controllably electrically excited by applying an AC voltage to the multiple probes relative to the conductive surface, wherein a non-conductive material is disposed between (i) the conductive surface or at least one of the multiple probes and (ii) a corresponding electrical contact associated with the multiple devices; and Signals emitted from the plurality of devices are detected based on the electrical excitation of the plurality of devices.

12. The method of claim 11, wherein the plurality of respective devices are a first plurality of said respective devices in a batch of respective devices and the plurality of probes electrically excite the first plurality of said respective devices, and wherein the method further comprises: Move at least one of the plurality of probes or the DUT, wherein the movement electrically excites the plurality of individual devices immediately following the batch of individual devices; Signals emitted from the plurality of following devices are detected based on the electrical excitation of the plurality of following devices. as well as For one or more additional devices, the movement and the detection are repeated once or multiple times.

13. The method of claim 11, wherein the plurality of respective devices are a first plurality of said respective devices in a batch of said respective devices, wherein the plurality of probes are in physical contact with the DUT, and wherein the method further comprises: While maintaining the physical contact between the plurality of probes and the DUT, at least one of the plurality of probes or the DUT is moved, wherein the movement electrically excites the plurality of individual devices immediately following each of the batch of individual devices; Signals emitted from the plurality of following devices are detected based on the electrical excitation of the plurality of following devices. as well as For each of the multiple devices in one or more additional devices, the movement and the detection are repeated once or multiple times.

14. The method of claim 11, wherein the conductive surface is transparent, and wherein the detection is performed from the second side of the DUT based on the signal passing through the transparent conductive surface.

15. The method of claim 11, wherein the DUT includes a non-conductive layer above the respective devices, wherein the plurality of probes include flexible probe ends that flex when in physical contact with the non-conductive layer of the DUT.

Images