Method and probe for exciting, detecting and sensing device under test

Abstract

Methods and probes for exciting, detecting, and sensing a sample are disclosed. An example method includes positioning a probe of a test tool relative to a contact point associated with a sample of a sample array such that the probe is in electrical contact with the sample array at the contact point; driving a parallel electrical excitation of the sample, where the electrical contact between the probe and the contact point is continuously maintained while the driving is performed, and the parallel electrical excitation of the sample produces a value for testing the sample; and repeating the above operation on other contact points for one or more times. Another example method submerges a probe in a liquid conductive material to provide a conductive liquid at its end of the probe, and may continuously position and / or move the probe relative to a contact point of a sample to facilitate delivery of an electrical signal to drive excitation of the sample.

Description

Background Art

[0001] Devices such as electronic, optoelectronic, electromechanical, and other types of devices can be inspected and tested. An example is electrical excitation, which applies a voltage or current to contacts that are in electrical communication with the device. Typically, in this example, the device and contacts are part of the same circuit, and the application of current / voltage is to drive the excitation of the device to produce various signals, such as emission values ​​and reflection values. These signals can then be optically and / or electrically monitored or sensed and recorded for analysis. The device subjected to such testing can be referred to as a device under test (DUT). Summary of the invention

[0002] Typically, there are many devices on a wafer or other surface to be tested, and it is desirable and advantageous to devise methods that can be applied to test the devices via parallel electrical, electrochemical, optical or other such excitations with parallel detection or sensing, or both. Thus, a DUT (which may also be referred to herein as a "sample") may refer doubly to each individual device under test as well as to a collection of individual devices, whether tested simultaneously or continuously.

[0003] By providing a method / procedure, the shortcomings of the prior art are overcome and additional advantages are provided. An example method is for testing a sample array including individual samples. The method uses a testing tool including a plurality of conductive test probes, and the method includes: positioning a plurality of test probes relative to a first plurality of contact points of the sample array, the first plurality of contact points being associated with a first plurality of individual samples of the sample array, so that the plurality of test probes make electrical contact with the sample array at the first plurality of contact points; driving parallel electrical excitation of the first plurality of individual samples by one or more electrical signals delivered to the first plurality of contact points via the plurality of test probes, wherein electrical contact between the plurality of test probes and the first plurality of contact points is continuously maintained while driving the parallel electrical excitation of the first plurality of individual samples, and wherein the parallel electrical excitation of the first plurality of individual samples generates a first value for testing the first plurality of individual samples; and a sample array, moving a plurality of test probes relative to the sample array so that based on the movement, the plurality of test probes are positioned relative to a next plurality of contact points so that the plurality of test probes make electrical contact with the next plurality of contact points, the next plurality of contact points being associated with a next plurality of individual samples of the sample array; and driving parallel electrical excitation of the next plurality of individual samples by one or more electrical signals delivered to the next plurality of contact points via the plurality of test probes, wherein electrical contact between the plurality of test probes and the next plurality of contact points is continuously maintained while driving the parallel electrical excitation of the next plurality of individual samples, and wherein the parallel electrical excitation of the first plurality of individual samples produces a second value for testing the next plurality of individual samples.

[0004] In one embodiment, the individual samples are micro light emitting diode (microLED) devices.

[0005] In some embodiments, driving parallel electrical excitation of the first plurality of individual samples is performed without using active feedback to continuously maintain electrical contact between the plurality of test probes and the first plurality of first contact points while driving parallel electrical excitation of the first plurality of individual samples is performed.

[0006] In one embodiment, the process further includes observing luminescence from the first plurality of individual samples based on interaction of the plurality of test probes with the first plurality of contact points, and confirming that electrical contact has been made between the plurality of test probes and the first plurality of contact points based on the luminescence, and the driving is performed in response to the confirmation.

[0007] In a specific example, the procedure further includes: as part of positioning a plurality of test probes relative to a first plurality of contact points, observing reflected signals from the plurality of test probes, and confirming that electrical contact has been made between the plurality of test probes and the first plurality of contact points based on the observed reflected signals, wherein parallel electrical excitation that drives the first plurality of individual samples is performed in response to the confirmation.

[0008] In one embodiment, at least a portion of each test probe of the plurality of test probes is made of a translucent material.

[0009] In one embodiment, the plurality of test probes comprises a test probe array having equidistant spacing between the test probes of the test probe array.

[0010] In addition, a method for testing a sample is provided, and the method includes: immersing at least a portion of a conductive test probe of a test device in a liquid conductive material; removing at least a portion of the immersed test probe from the liquid conductive material, wherein a portion of the liquid conductive material remains on an end of the test probe and is in electrical contact with a conductive portion of the test probe; positioning the test probe relative to a contact point of the sample so that the portion of the liquid conductive material on the end of the test probe makes physical contact with the contact point of the sample; and driving excitation of the sample by an electrical signal delivered to the contact point via the test probe through the portion of the liquid conductive material on the end of the test probe.

[0011] In a specific example, the positioning positions the end of the test probe relative to the contact point so that the end of the test probe is physically spaced apart from the contact point, wherein a portion of the liquid conductive material occupies at least the space between the end of the test probe and the contact point and electrically bridges the conductive portion of the test probe and the contact point.

[0012] In one embodiment, the sample is a micro light emitting diode (microLED) device.

[0013] In one embodiment, the liquid conductive material is metallic. In some such embodiments, the liquid conductive material comprises gallium.

[0014] In a specific example, the procedure further includes monitoring an electrical signal from the test probe, and determining whether electrical contact has been made with the contact point based on the monitored electrical signal.

[0015] In a specific example, the test probe is one of several test probes of a test device, wherein the sample is one of a sample array, and wherein immersion, removal, positioning and driving are performed using each of the several test probes to electrically couple each test probe with a respective contact point of a respective sample of the sample array and drive excitation of the respective sample.

[0016] Additionally, an apparatus for testing a device under test (DUT), the DUT comprising a plurality of individual devices, and the apparatus comprising a probe array, an alignment system for aligning the DUT and the probe array relative to each other, and a detection system configured to detect signals from the plurality of individual devices, wherein the apparatus is configured to test the individual device groups of the plurality of devices by scanning electrical contacts of the individual device groups while driving electrical excitation of the electrical contacts.

[0017] In an embodiment, scanning includes moving the probe array relative to the DUT by moving at least one of the probe arrays and the DUT, wherein the movement brings the probe array into contact with respective sets of electrical contacts of respective ones of the individual sets of devices.

[0018] In a specific example, the movement repeatedly brings the probe array into contact with respective sets of electrical contacts of respective device groups, wherein the movement brings the probe array (i) into contact with one set of electrical contacts of one of the individual device groups, then (ii) out of contact with one set of electrical contacts of one of the individual device groups, and then (iii) into contact with another set of electrical contacts of another of the individual device groups.

[0019] In a specific example, scanning includes scanning the DUT beneath the probe array.

[0020] In a specific example, the alignment system is further used to level the DUT relative to the probe array.

[0021] In a specific example, the signal comprises an optical, electrical or electrochemical signal from a respective device, and the tool is further configured to detect the optical, electrical or electrochemical signal using a detection system. In an example, the tool can generate such a signal with or without excitation (capable of detecting spontaneous emission).

[0022] Additional aspects of the present disclosure are directed to systems and computer program products configured to perform the methods described above and herein. This summary is not intended to illustrate every aspect, every implementation, and / or every specific example of the present disclosure. Additional functions and advantages are achieved by the concepts described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] At the end of the specification, the aspects described herein are particularly pointed out and distinctly claimed as examples in the claims. The foregoing and other objects, features and advantages of the present disclosure will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0024] Figures 1A to 1E Describes an example environment and its components for incorporating and using aspects described herein;

[0025] Figure 2 depicts examples of alternative configurations of probe arrays extending from probe array arms according to aspects described herein;

[0026] FIG. 3A to FIG. 3B Depicts additional examples of probes according to aspects described herein;

[0027] Figure 4A depicts an example of a probe tip according to aspects described herein that has been dipped into, and then removed from, a liquid conductive material;

[0028] Figure 4B depicts an example of electrical coupling between a probe tip having a conductive material on one end thereof and a flat contact according to aspects described herein;

[0029] FIG. 5A to FIG. 5B depicts observable changes based on immersion of a probe tip into a liquid conductive material according to aspects described herein;

[0030] FIG. 6A to FIG. 6C depicts further observable changes based on immersion of the probe tip into a liquid conductive material according to aspects described herein;

[0031] Figure 7 Describes an example test apparatus and setup for DUT measurement that may incorporate aspects discussed herein;

[0032] FIG. 8A to FIG. 8C Depicting example electrical and optical indicators of the conductive state of a probe according to aspects described herein;

[0033] 9A to 9C depicts an example of electrical-based leveling of a probe array according to aspects described herein;

[0034] FIG. 10A to FIG. 10C depicts a continuous excitation when testing a DUT according to aspects described herein;

[0035] Fig.11 Describes another example environment and components thereof for incorporating and using the various aspects described herein;

[0036] Figure 12 to Figure 13 Describes an example procedure for testing samples according to aspects described herein; and

[0037] Fig.14 One example of a computer system and associated devices for incorporating and / or using aspects described herein is depicted. DETAILED DESCRIPTION

[0038] Facilities, such as tools and methods, for exciting and testing devices, such as those provided on a surface / substrate, are described herein. In some aspects, the induced excitation of a DUT can be repeatedly applied with minimal or no degradation in the tool or DUT's efficacy. Geometries that meet the intended use conditions of the tool enable transparent optical or other forms of readout generated by such excitation to facilitate evaluation of the DUT's performance.

[0039] One of several examples of such testing is electro-electroluminescence for micro-light emitting diode (also referred to as "microLED," "micro-LED," "mLED," and "μLED") display inspection. Many of the examples described herein are presented with reference to testing of microLEDs. MicroLED testing can be particularly useful for microLED display inspection. MicroLED displays incorporate millions of MicroLEDs, and efficiently testing them is a key step in enabling large-scale manufacturing and sales of MicroLED displays.

[0040] The aspects described herein enable parallel testing using probe arrays. Parallel testing according to the aspects described herein can achieve excellent, consistent and repeatable results. Examples involve parallel electrical interactions to effectively excite arrays of devices for inspection. Although the features described herein are presented with specific reference to microLEDs, those of ordinary skill in the art will appreciate that the features described herein can be used to test / inspect a variety of devices and multiple types of samples, including electromechanical, electro-optical, and other types of devices / samples (including electrochemical and chemical), and further, that the aspects can be applied to both single-component testing and multiple-component testing, such as arrays of devices.

[0041] In some embodiments, a tool is provided that operates as a series of probes to apply voltage or current to contact points to stimulate a number of corresponding devices (e.g., electronic, optoelectronic, or electromechanical DUTs, as examples), and then optically and / or electrically monitor signals generated from the stimulated devices. The probes make electrical contact in parallel at multiple locations.

[0042] In contact-based testing, the probe is placed in physical contact with the contact point and a certain perceptible level of force is applied. In order to ensure proper contact between the probe array and the corresponding contact point and avoid damage to the probe and / or DUT, the physical interaction between the probe and the contact point can be monitored, including the force of the probe touching the contact point after the initial contact. Adjustments can then be made as appropriate to ensure that the probe remains in contact with the associated contact point with the appropriate contact force applied. After the initial contact, the actions and interventions taken based on the observed signals and other indications of this physical interaction monitored are forms of "feedback". More specifically, such activities taken to maintain contact after the initial contact are called "active" feedback, and monitoring / adjustments occur as part of a feedback-based method to position the test tool relative to the DUT and possibly level the test tool. Excessive pressure can damage the probe and / or DUT, but as described in accordance with the embodiments herein, various methods can be used to avoid such damage.

[0043] Alternatively, the probes may be made to be appropriately flexible, "soft touch" / flexible in nature, and these may be applied as active feedback with or without the need for monitoring and adjustment to adjust its flex or bend, such as when the end of a paint brush would flex / bend. Where active feedback is implemented, an electronic or other signal may be altered based on the force applied to identify the appropriate adjustment needed to maintain the desired force.

[0044] The methods and devices discussed herein enable repeated parallel, flexible contact (electrical contact in some embodiments) and interaction to excite multiple devices under test with functional efficacy without damaging the probes or devices, and without requiring and / or taking any measurement / monitoring of active feedback (but permitting such active feedback when so desired). In some embodiments, this is provided via appropriate mechanical properties so that the plurality of probes can repeatably interact appropriately with the electrical contacts of the device without damaging the probes or device structure. Additionally, as described herein, the use of liquid metal to act as a flexible interface between the device and the probe(s) may also be provided. Thus, in embodiments once electrical contact has been established, as an example, device excitation may be observed optically (e.g., as an example, by the human eye or by a camera or other optical / imaging system) and / or electrically, but as an example, active feedback (such as feedback including continuous checking of electrical signals to identify whether electrical contact is broken or for leveling purposes or to check that the applied force remains appropriate) may be optional.

[0045] Depending on the specific DUT, the probe configuration may vary. When considering a probe configuration of several probes (arrays), a flexible probe array may be fabricated with appropriate spacing and geometry to provide an unobstructed view of the DUT at the highest magnification of an optical microscope when exciting the DUT when desired. Silicon-based and other microfabrication technologies, such as 3D printing, may provide the technology needed to fabricate probe arrays with the appropriate flexibility, mechanical properties, geometry, and electrical patterns to provide the necessary electrical inputs and outputs dictated by the specific parameters of the DUT to achieve the desired excitation.

[0046] As a specific example, a matrix or array of probes may be provided, such as provided as part of a patterned board or card, and may be configured so that connections (such as electrical connections) made by the probe array to the DUT may be detected, such as electrically detected. This is useful for leveling and aligning the probe array relative to the DUT. Leveling, whether based on electrical contact / interaction, mechanical leveling, or optical leveling, or otherwise, may be an important part of a test procedure. With electrical contact-based leveling, it may be desirable to detect if and when interaction occurs between the test probes and the electrical contacts of the DUT to drive electrical excitation. Detection of such electrical connections between the tool and the device under test is important for leveling the tool (e.g., its probe array) on the surface of a wafer or other substrate with the device under test and ensuring that accurate test results are obtained. Other aspects of probe-surface interaction may also be used to level the probes of the test device. Capacitive signals, and even optical signals, may be implemented to align the probes to the surface. For example, the capacitive signal may excite the device under test, which provides a contact indication that may be used for leveling purposes.

[0047] In addition to the probe itself providing a signal for alignment, there are other leveling and alignment methods, which conventionally require high precision and relative alignment. These methods are commonly used in the semiconductor industry for precise interaction between tools and wafers on which devices are patterned. In a specific example, the implementation for leveling and alignment may include the following subassemblies: a wafer loader, a wafer stage, a wafer alignment system, a loader for a test tool, a tool stage and an alignment system, and an optical detection system. After many years of development in the semiconductor industry, all of these subassemblies are easily available and can be implemented with the aspects discussed herein. In some examples, it may be provided as a housing in some examples, and the housing maintains a precise temperature to control the precise temperature of the expansion or contraction of the wafer caused by temperature changes. The housing may optionally also include other systems that support the program, such as air conditioners, power supplies, control panels, and various other electrical components and subassemblies as examples to achieve the aspects described herein.

[0048] Fabrication techniques applied to aspects described herein, such as the fabrication of probe arrays, can allow for various changes, an example of which is a change in the spacing between probes for proper alignment to an array of devices under test. In an example, the devices can be spaced at micron, submicron, or nanometer sizes.

[0049] Aspects contemplate and allow for various geometries with respect to electrical contact between the probe's test tool and the DUT. For example, where each device in an array of devices to be tested is associated with two electrical contacts (e.g., positive and negative polarity), the respective two electrical contacts of each individual device in the array may be located on both sides of the individual device (i.e., one positive (P) or lead contact proximate one side of the device, and one negative (N) or ground contact proximate the other side of the device). Alternatively, a single contact may be used as a first contact (such as a ground contact) for all devices under test, and for each such device, a respective second contact / pad (as a lead contact) may be used for each device and placed proximate to the side of that device. One specific example is a geometry in which a single contact provided at one side (e.g., bottom) of a wafer / substrate / plane on which the devices are provided is used as a first contact (e.g., ground) for each device, and a respective second contact (lead contact) for each device is provided on the other side (opposite side, top) of the wafer / substrate / plane. Other geometries are also possible.

[0050] In the case of an optoelectronic device under test, such as a microLED-based display, the microLEDs of the DU emit light due to, for example, electroluminescence, and this emitted light is measured for each microLED - that is, a separate measurement of the light emitted from each microLED can be obtained as an indication of the individual performance of each such microLED. Accurate measurement can be challenging if the probe array obstructs the optical means for measuring the emitted light. When the probe contact point is on the same side of the test sample as the individual device under test (microLED), then the probe tip that makes contact at the contact point can be constructed with an appropriate geometry so that light emitted from the device under test is not blocked or substantially undisturbed.

[0051] As examples, the emission signal or other response of the DUT in response to its excitation can be optically observed from above, below, and / or from the opposite side of the excitation. In some embodiments, a flat transparent surface, such as the surface on which the probe array is placed or coupled, is used for mechanical support and strength or other purposes, and also allows the emission light to pass therethrough for detection. It can also allow for excitation using tools that can be driven by illuminating a wafer or device structure through a transparent surface, and then measuring the photovoltage or photocurrent generated in response. This can be an approach taken in solar array testing, for example, where a voltage is generated with light or other solar excitation.

[0052] The microfabrication (geometry, spacing, etc.) of the probe array can adjust the properties (geometry, spacing, etc.) of the devices on the DUT regardless of the mode of device monitoring, whether electrical response, device photovoltage / photocurrent response, photoluminescence, capacitive response, or other forms of response. Thus, an integrated structure of the DUT and the measurement tool (e.g., probe array) is obtained.

[0053] Figures 1A to 1E Depicts an example environment and its components for incorporating and using the aspects described herein. Figure 1A , this environment may be useful in electrical excitation devices for testing / inspection. Figure 1A , an example individual device under test (DUT) is labeled 100. It should be noted that DUT may refer to a collection of such devices 100 or each individual device 100 itself.

[0054] Each DUT 100 may be an electronic, optoelectronic, or electromechanical (as examples) device under test, and each device may be disposed on a plane (not shown) such as a wafer or other substrate, eg, as part of an integrated circuit.

[0055] The test device (sometimes referred to as a "tool" or "test array") in this example includes a frame / structure 102 that holds an array of probes 110. The frame 102 includes cross supports 106, 108, between which extend probe array arms 104a, 104b, 104c. Each such probe array arm 104a, 104b, 104c holds a respective number of probes 110 as a sub-array. It should be noted that the depicted frame 102 and associated probes may be merely a section of a larger frame structure and probe collection / array of a tool. Thus, section 102 may be copied / repeated to form a more extensive test tool. The length of each cross-guide section 106, 108, and more generally the size of any components depicted and described, may be of any desired size and dimension. By way of example only and not limitation, the length of each cross-guide section 106, 108 may be 15,400 μm. By way of example only, Figure 1B The size of the probe array arm 104a is depicted as 2400 μm long, 93 μm wide, and 18 μm high (height). The frame 102, including its components, its size, spacing, etc., and the probe size, spacing, etc. can be customized according to the layout and size of the device under test. The probe array can be constructed to facilitate lifting and placing it on the device with the correct spacing and geometry to make proper contact with the contacts of the DUT.

[0056] Each probe 110 of the probe array may be a cantilever having a body portion and a tip portion. As an example only, Figure 1C The dimensions of an example probe 110 are depicted. The body portion 120 has a base 122 having a length of 22 μm, a side 124 having a length of 107 μm, and a thickness of 1 μm. In this example, the tip portion 128 has a length of at least 15 μm. If desired, the body and tip portions of the probe 110 can be constructed from common materials as an integral device.

[0057] In a specific example, the probe or a portion thereof may be configured and customized to have an appropriate flexibility, which may be customized to at least a selected amount. For example, each probe may be configured with an appropriate force / spring constant, such as 1.0 Newtons / meter (N / m) or less per meter for a specific material such as silicon. In some specific examples, the constant is between 0.3 and 1.0 (including 0.3 and 1.0). However, it is well known that the actual force depends on the material of the probe and may also vary due to geometry, thus allowing various force constants to be adjusted for such tests. In addition, as described, if a liquid conductive material such as gallium is used in a specific example described elsewhere herein, this allows other, i.e., significantly larger force constants. In addition, depending on various conditions, such as the angle or thickness of the cantilever required for the specific geometry of the DUT, the desired force constant will vary (e.g., an order of magnitude higher or lower using the same manufacturing technology). In some specific examples, the probe will have a force constant selected to allow for appropriate flexibility so that when it reaches and presses against a contact point, it will not break and will not cause undue damage to the DUT. In addition, the body portion 120 of the probe can extend at a first angle (from the probe array arms 104a, 104b, 104c), and the tip portion 128 forming the end of the probe (at the very end of the tip, relative to the distal end of the probe arm) can extend at another angle relative to the first angle (i.e., at an angle relative to the body portion 120). In this way, the exemplary probe 110 is provided with a bend or other change in direction in the probe region between its base and its tip, and extends at the angular change in that region.

[0058] Return to reference Figure 1A , the frame 102 can be positioned relative to the DUT so that the probes of the probe array make contact with various contact points (also referred to as "contacts", "contact pads", "contact points", or simply "pads") to stimulate the DUT. In this regard, and in this particular example, each device under test 100 (a microLED in this example) is associated with a respective unique pair of contact pads—as examples, one contact pad as a lead and the other contact pad as a ground, or one contact pad as a positive (+) polarity contact and the other contact pad as a negative (-) polarity contact. Figure 1A Associated with the DUT 100 in the diagram are pads 112 and 114, with probes 116 and 118 making contact with pads 112 and 114, respectively. It should be understood that pads 112, 114 are in electrical contact with the DUT 100 so that the DUT 100 can be stimulated by a voltage / current applied through the probes. As an example, one of the pair of probes may be a voltage source, and the other of the pair of probes may be a voltage sink.

[0059] Just as an example, Figure 1D Depicted are example contact pads (e.g., Figure 1A 112), the size of which is 20 μm×12 μm and the height is 0.25 μm. As an example only, Figure 1E The size of an example microLED 100 (device under test) is depicted, with dimensions of 5 μm x 5 μm and a height of 1.5 μm. These are example sizes and do not limit the geometries of DUTs and associated components that may be used with aspects discussed herein.

[0060] Excitation of individual DUTs, in this example, microLEDs, can be done by applying a voltage or inducing a current that causes the microLEDs to illuminate. Probes make electrical contact with corresponding contact points / pads to make electrical connections with the contact points. These contact points are part of / incorporated into the device to be excited (such as the microLED itself), or are electrically connected to the device, for example by electrical vias, leads, pins, routes, traces, or the like. The voltage / current can be varied to monitor the response of the microLED to this variation, and within a range of variation. In the case of microLEDs and other types of optoelectronic devices, light sensors can be used to measure the light emitted therefrom. Although in Figure 1A Not shown, but a transparent panel of glass or other material may be placed as a support for the probe array, or may be otherwise positioned between the device under test and the optical sensor while allowing light from the DUT to pass through (e.g., upward) to be measured. Typically, although not always, all of the devices being tested, or a discrete subset of such devices, are part of the same underlying device, such as a display panel in the case of microLEDs, and the electrical contacts used in the test may be patterned and formed in the process of forming the underlying device. Alternatively, the electrical contacts used in the test may be patterned and formed separately from the formation of the underlying device.

[0061] exist Figure 1A In the example of the probe array, the cantilever design of the probes of the probe array fully exposes the light emitted from the microLEDs to the area above the DUT. Therefore, the optical sensor (not shown) can be configured above the DUT and probe array portion of the test tool so that the probes do not interfere with the optical exposure and detection of the sensor. In an alternative configuration (so-called "flip chip" design) where the contacts are on one side (e.g., top and bottom) of the DUT substrate and the DUT is on the other side (e.g., bottom or top), interference of the probes with the light emitted by the microLEDs may not be such an issue.

[0062] Fig.11 Another example environment and components thereof are depicted for incorporating and using the various aspects described herein. Fig.11A section of a device array and a corresponding section of a test tool for testing the section of the device array are depicted. Here, the section of the device array includes a 4×4 array of (sixteen) devices 1100. The PXLx pitch refers to the spacing in the x dimension ( Fig.11 The PXLy spacing refers to the spacing (interval) between devices 1100 in the horizontal direction in the y dimension ( Fig.11 The spacing in the vertical direction).

[0063] The depicted portion of the test tool includes two electroluminescent (EL) contact probe arms 1110a and 1110b, each probe arm having 6 probes extending therefrom, and more specifically, each probe arm having three probes extending to contacts on one side (e.g., the left side) of the EL contact probe arm and three probes extending to contacts on the other side (e.g., the right side) of the EL contact probe arm. Probes are configured along each EL contact probe arm in this manner so that the EL probe arm can detect devices on each of the two sides of the arm, and thus the EL contact probe arm is extended in the y dimension between every other column of the device array, as shown, with corresponding spacing in the x dimension (ELx spacing). At the same time, the probes on the same EL contact probe arm are spaced apart in the y dimension according to the spacing of the excitation contact points at the device (Ely spacing).

[0064] Each device 1100 has two associated contact points. As an example, using Fig.11 100, device 1100 has an associated first contact point 1102 and an associated second contact point 1104. Contact point 1102 is the contact point that stimulates device 1100 via probe 1106 extending from EL contact probe arm 1110a. Contact point 1104 is a common ground point that is electrically connected to other ground contacts of device 1100 in the same column (x dimension) via a common ground (CG) line. In this example, Elx pitch = 2*PXLx pitch, Ely pitch = PXLy pitch, and the common ground line can be on a wafer (not shown) to which device 1100 is coupled.

[0065] Figure 2An example of an alternative configuration of a probe array extending from a probe array arm 204 is depicted. Here, the probe array arm 204 provides cantilever probes in pairs, where each pair of probes is configured and sized to provide contact and electrical interaction with two contacts associated with a given device under test (e.g., a microLED). The probe array arm 204 provides two columns of probes—one column of probes each of a first length, and the other column of probes each of a second length, the first length being longer than the second length. The probes 206a and 206b in the longer probe column will provide two contacts for testing a first device 1100 (such as by traversing the device to reach individual contacts on each side of the device), while the probes 206c and 206d in the shorter probe column will provide two contacts for testing a second device 1100 (such as by traversing the device to reach individual contacts on each side of the device). The various other probe pairs depicted are used to test other devices 1100 or for testing alternative geometries of devices.

[0066] Figure 3A Another example of a probe according to aspects described herein is depicted. Probe 300 may be cantilevered relative to a probe array arm (not shown), for example having a protruding body portion 302 extending at a first angle from the probe array arm and a tip portion 304 forming an end of the probe, the tip portion extending at another angle relative to the first angle (i.e., at an angle relative to the body portion 302). Thus, when moving along the probe from the base end (from which the probe extends from the probe array arm to the end / tip of the probe), a change in direction is provided at region 306, which is the interface between the body portion 302 and the tip portion 304. It should also be noted that in this example, the probe is configured to have a generally flat surface with a narrowing size converging at the probe tip 308, resulting in edges 309a, 309b, 309b extending along the probe in the direction of extension of the probe. In some applications, it may be preferred that the probe / probe tip protrude outwardly and away from the coupling structure (such as the probe array arm) so as not to obstruct the optics / line of sight to observe the effects of electrical excitation.

[0067] Figure 3B Another example of a probe according to aspects described herein is depicted. Here, a probe 310 having one end extends from a probe array arm 312 in a substantially single direction (in Figure 3B In the example of , the end of the probe array arm is vertical and close). This is similar to Figure 3A In contrast to the geometric shapes in Figure 3A , there is a bend in the probe 300. This configuration may be useful where the contact pads are on one side of the DUT and the excitation characteristics (e.g., emitted light) are observed from the other side of the DUT, where there is no need to bend or flex the probe to provide greater optical exposure for the excitation characteristics.

[0068] In any case, the probe may be an integral element, and in some cases, formed of a single or multiple materials. In an example, the material includes one (or more) conductive materials. It should be noted that the probe / material does not have to be completely conductive; in an example, the probe includes silicon with a gold (or other material) coating. However, in terms of materials / compositions (as explained elsewhere herein), the probe may have a channel through which a liquid conductive material is provided to the end of the probe, and a droplet of liquid conductive material is provided through its opening. As a specific example, the probe may be made of silicon, silicon nitride, polymers, etc. in part or in whole. At least some of the aforementioned materials (e.g., at least silicon nitride) are known to be translucent. It may be necessary to appropriately coat the material so that it provides high conductivity. In addition, in some specific examples, the probe will have a selected force constant to allow appropriate flexibility so that when it touches and presses against the contact point, it will not break and will not cause undue damage to the DUT. Factors for achieving the above situation include appropriate material selection, appropriate geometry, and appropriate dimensions of the probe, probe array, and the frame / support structure of the probe array. Different geometries of cantilever probes having different distributions and / or lengths and spacings are described herein.

[0069] It should also be noted that while flexibility of some or all of the probe may be desirable and / or necessary, in such cases, a sufficiently high force constant may be desired at least at the probe tip to maintain the probe tip structure as the probe tip physically interacts with the contact pad. As described elsewhere herein, in some cases, flexibility or lack thereof may be inconsequential and optional, such as when a liquid conductive material is provided in conjunction with a probe as described below.

[0070] According to the aspects described herein, the electrical connection / coupling between the probe tip and the contact pad to provide electrical excitation can be provided by means of a variable separation of the probe tip itself from the contact pad. This can be provided without compromising conductivity while still providing effective, repeatable and uniform excitation for the device under test. For such contact, a conductive liquid material, such as a liquid metal, can be used. Therefore, according to some aspects, before the probe contacts the contact pad of the DUT, a liquid conductive material is applied to the probe while still at least partially in liquid form. One method of applying such a liquid conductive material to a solid probe is to dip the protruding probe into the liquid conductive material. Such an operation can be completed without damaging its array / probe. The conductive material in liquid form adheres to the outer surface of the probe and forms a relatively high conductivity liquid buffer on the outside of the probe tip.

[0071] As a specific example and not limiting, liquid gallium may be used due to its high conductivity and other convenient properties, including its melting point (about 30°C). Although the examples described herein indicate gallium as the liquid conductive material, this is only one non-limiting example and does not exclude the use of other conductive materials, such as metallic inks or conductive solutions now existing or later developed. In general, the conductive material may be selected for its conductive, mechanical, physical and / or elastic properties, depending on the specific application in which it is used. Gallium is a liquid metal at temperatures around room temperature that are convenient for production processes, and has unique properties that are extremely suitable for applications such as microLED inspection.

[0072] Figure 4A An example of a probe tip according to aspects described herein that has been dipped into and then removed from a liquid conductive material is depicted. Probe 400 has a body portion 402 and a tip portion 404, and tip portion 404 has been partially dipped into and then removed from a pool of liquid gallium 420. Thus, a droplet 410 of liquid gallium remains on probe tip 404, surrounding a portion thereof.

[0073] A "pocket" in the form of a droplet forms and adheres to the probe tip. Depending on physical and / or chemical processes / changes that may occur after the probe tip is removed from the liquid gallium (which physical / chemical changes may depend on the environment and other conditions in which the test occurs), a relatively thin (e.g., micrometer or nanometer) protective layer 414 of the droplet 410 may form. An example of such a chemical change may be the formation of a molecular gallium oxide layer that is, for example, a few nanometers thick. Additionally or alternatively, other changes to the gallium may occur at the probe tip, such as partial solidification ("cooling") of the liquid gallium at the droplet surface to produce the layer 414 and / or render the droplet partially / wholly a ductile solid, as an example.

[0074] At the same time, the interior 412 of the "bag" can hold liquid gallium protected by a protective layer 414. As an example, an example of oxidation is used to create an oxide bag with a protective oxide layer 414, which prevents and protects the internal liquid gallium 412 within the oxide bag from further oxidation or rusting. The ability to form an oxide-coated conductive liquid conductive material (e.g., gallium) micro / nano droplet that seals the probe tip is a result of the high flexibility of gallium (or similar liquid metals). The bag formed with the oxide layer acts like an air bag, except that it can be quickly resealed if punctured. As described herein, the size of the droplet and its bag perimeter conforms to the fit around the probe tip and to the surface it contacts, and therefore the size of the bag and oxide surface 414 (in such examples) can vary at least in part with the size of the probe tip.

[0075] The probe 400 so coated can be lifted / removed from the pool 420 after dipping into the liquid conductive material without breaking the seal around the tip, and this can be at least partially attributed to the presence of the layer 414 (e.g., nano-oxide layer) of the bag around the tip, which itself can have a protective coating applied thereto.

[0076] In some examples, the liquid conductive material is alternatively (or additionally) introduced to the end of the probe by means of a channel, conduit, passage, or other feature of the probe itself (e.g., by means of the probe body and to the probe tip, as an example). For example, the probe may be partially hollow, and the liquid conductive material may be delivered to and through an opening on one end of the probe, similar to ink being delivered to the tip of a pen by means of a pen body. The liquid conductive material may originate from a reservoir from which the liquid conductive material flows, or otherwise be provided to a channel / conduit / passage extending through the probe so that the liquid conductive material flows through the probe to one end thereof. The reservoir may provide liquid conductive material to multiple probes. In an example, when the liquid conductive material is delivered to / through the opening at the end of the probe, a droplet of the liquid conductive material is formed on the end of each test probe.

[0077] Droplets of liquid conductive material on an array of probe tips, whether formed by dipping or provided to the ends of the probes themselves, can facilitate alignment and leveling of the probes in their interaction with electrical contacts of the device under test, and can also achieve proper leveling and alignment without active feedback. As the probe tip with the pocket of conductive material moves closer to the appropriate contact of the DUT, the portion of the pocket opposite the probe tip (e.g., the bottom of the pocket) can contact the contact pad of the DUT, and thus the conductive material (opposite to the probe tip itself) interacts with the contact pad first. This can itself produce chemical and / or physical changes in the conductive material, such as forming nanopores in the oxide (in this example) portion of the pocket, and enable the probe tip to make electrical contact with the contact pad via the conductive material of the droplet without the probe tip actually physically touching the surface of the contact pad. At the same time, the liquid state of the conductive material provides a cushion or "pad" for the probe tip so that it does not reach the resistance level it would otherwise reach if it touched the (solid) contact pad or if the conductive material on the tip was solid.

[0078] Thus, electrical interaction and / or contact between the probe tip and the contact point is provided without the probe tip making physical contact with the contact point. Thus, the tip of the probe can thereby electrically interact with the contact of the DUT without physically touching the contact or any other part of the DUT, because the conductive material acts as a medium for electrical communication / connection between the tip and the contact point of the DUT. Furthermore, due to the effective separation between the probe tip and the contact point, this condition can allow a tunneling current induced from the tip to the surface as a function of voltage.

[0079] Figure 4B An example of electrical coupling between a probe tip having a conductive material on one end thereof and a flat contact according to aspects described herein is depicted. As shown, a probe 400 having a liquid conductive material 412 has been positioned relative to a contact 422 (i.e., in electrical communication with a device for testing) such that a droplet 410 of the liquid conductive material 412 physically touches the contact 422 at a number of consecutive points on a flat contact area 424. As shown, the droplet 410 becomes deformed (relative to its position at the flat contact area 424). Figure 4A ), and there is a space 416 between contact 422 and the end of the probe tip closest to contact 422 (i.e., at the end of the probe). Although there is no direct physical contact between any part of the probe and contact 422, the conductive material still electrically couples the probe to contact 422.

[0080] In a specific example, when a probe with a droplet of liquid conductive material contacts a DUT contact pad, pinholes may be formed in the oxide layer of the pocket. Such pinholes allow the liquid conductive material to act as a contact bridge between the probe tip and the pad on the DUT. In this case, the outer oxide layer may serve to contain the interior of the liquid conductive material so that the liquid does not flow onto the surface of the contact pad and does not substantially move away from the probe tip. In addition, to the extent that the probe tip may have been pressed / moved further toward the contact pad by the droplet to "pierce" the oxide layer interfacing with the liquid material and the contact pad, any such pinholes may be sealed when the probe tip is lifted from the contact. That is, they may be quickly and automatically repaired by chemical and / or physical processes associated with the liquid conductive material (gallium in these examples), such as by reoxidation or oxide phase change, as an example of pulling the probe back away from the DUT.

[0081] Thus, portions of the probe, such as the probe tip, portions thereof, and / or other portions of the probe, can be introduced into a pool of gallium or other liquid conductive material and then lifted from the pool to provide a droplet on the probe, and / or the droplet can remain intact around the probe (in these examples, the tip) due to the presence of the nanooxide portion of the bag. Thus, the probe can be easily moved from the immersion liquid to the sample (e.g., DUT) without losing liquid. Additionally, after stimulating one or more devices, the probe can be lifted from the corresponding contact point and retain the droplet of liquid conductive material thereon. Any conductive material that may leak onto the contact point is negligible. The array and sample can then be repositioned relative to each other without loss of liquid from the probe, so as to enable repeat testing of other DUTs, for example by moving the probe array and / or by moving the sample under the probe array to facilitate interaction of the probe with another group of contact points. If necessary, the probe array can be re-immersed in gallium between repositioning.

[0082] Such aspects can help eliminate or minimize wear and other degradation of the probe tip while enabling repeatable, flexible contact with the DUT and addressing common issues with single or multiple probes interacting with the device. Additionally, electrical contact with the DUT can be maintained with or without the aid and guidance of feedback because electrical contact with the DUT can be achieved without the probe tip physically contacting the surface of the contact pad. In this regard, specific examples see the probe operating in a non-contact mode, where the probe / probe tip itself does not physically contact the contact point, but instead electrically communicates via a conductive material in the form of a droplet that electrically couples the probe tip and the contact point, and this coupling and any associated leveling / alignment between the probe and the DUT can be achieved in a tunneling mode of contact of the DUT without the use of active feedback.

[0083] Note that in order to provide electrical excitation to the device under test, the conductive probe has a conductive portion thereof. In the above example, the probe is conductive at the end of the probe tip, and thus the droplet formed around the probe tip provides a conductive medium from the probe tip to the contact point engaged therewith. However, in some examples, the end of the probe is not necessarily conductive, but other parts are conductive. Therefore, the droplet of liquid conductive material may be large enough so that it is in electrical contact with the conductive portion of the probe. In this regard, the depth of the probe immersed in the liquid conductive material and / or the portion of the probe immersed in the liquid conductive material may be based on the position of the conductive portion of the probe, and in an example, how large the droplet is expected to ensure that there is conductivity between the probe itself and the liquid conductive material, so that when contact is made between the conductive material and the contact pad, electrical communication is performed from the probe to the contact pad. In this way, immersing at least a portion of the test probe in the liquid conductive material and removing the probe therefrom can provide a droplet of liquid conductive material that remains on the end of the test probe and is in electrical contact with the conductive portion of the test probe. The liquid conductive material on the end of the test probe may make physical contact with the respective contact points, and then the electrical signal may be delivered by the liquid conductive material through the test probe to the respective contact points.

[0084] The properties and characteristics of gallium make it a good candidate liquid conductive material for the applications discussed herein. Gallium is highly conductive, has a boiling point of 2400°C, melts at about 30°C, and has an extremely low to effectively zero vapor pressure at room temperature. Low vapor pressure can cause liquids to evaporate, but in the case of gallium droplets, the oxide layer described above prevents this from happening. Gallium can be used in air without the risk of inhalation, resulting in lower toxicity. In addition, gallium has a low viscosity, which would normally allow it to flow freely, but the oxide coating prevents it from flowing and gives gallium a high surface tension. Gallium has been approved by the U.S. Food and Drug Administration for human applications, such as magnetic resonance imaging. In addition, the human body has a natural ability to remove gallium. The properties of gallium also facilitate simple cleaning and removal, so that, for example, gallium materials can be removed from probe tips / ends / parts with high repeatability, or if any residue on the DUT needs to be removed by chance. For these and other reasons, gallium is substantially safe in industrial applications, with little or no need for personnel protection, and therefore may be ideal in certain applications of the specific examples of the aspects described herein.

[0085] Additionally, where desired in an inspection procedure, the use of gallium can allow the probe to be reversibly bonded to a contact surface via an adhesive bond, wherein the liquid gallium at least partially solidifies to adhere to the contact surface. As an example, the adhesive bond can be remotely reversed using infrared radiation or heating (e.g., electric Joule heating of wires integrated into the tool). The temperature for such reversible bonding can be about 23°C (depending on environmental and other conditions), wherein temperatures above this temperature result in complete peeling of the gallium from the surface with minimal adhesion.

[0086] These properties of gallium, whether used as a conductive bridge to allow non-contact, highly conductive electrical interaction between the probe and the device under test, or as an adhesive, make it useful for many cycles (contact, excitation of the device under test, lifting / movement, repetition, etc.) without replacement, because under the proper loading and unloading conditions, the liquid metal is essentially lifted from the contact surface. No residue is left on the contact surface, and (in the case of adhesive bonding) the adhesive loses little to no of its own material. Good adhesives are usually difficult to separate from the substrate, but the oxide shell of gallium (in this example) can help facilitate this removal, leaving minimal or no residue on the device. Such properties can be critical for applications of electrical contact and / or interaction.

[0087] Therefore, gallium (and similar metallic elements) with relatively low melting point, high conductivity, negligible vapor pressure, high surface tension, low viscosity and metallic properties may be good candidates for liquid conductive materials. Additionally, the reaction of gallium to form oxides, which has historically been considered an obstacle to the use of gallium in various applications, is beneficial in the context of the applications discussed herein.

[0088] As mentioned, gallium is only one example of a conductive material; other materials may work equally well or better depending on the particular application. Examples of suitable alternative liquid metals include, but are not limited to, eutectics of gallium and / or indium, gallium-indium-zinc, and gallium-indium-tin. Other highly conductive liquids yet to be developed may replace the use of gallium.

[0089] FIG. 5A to FIG. 5B Observable changes based on immersion of a probe tip into a liquid conductive material according to aspects described herein are depicted. More specifically, the figure depicts immersion of the probe into liquid gallium. In these examples, a semi-flexible cantilever probe 502 is shown in a top view, with the probe tip below the probe body (not shown). Figure 5A The probe 502 is depicted before the probe tip is immersed in a liquid gallium pool 504, and Figure 5B Probe 502 is depicted after the probe tip has been dipped and remains at least partially submerged in a pool 504 of gallium.

[0090] As probe 502 moves closer to pool 504, the probe tip is attracted to the gallium, and is thus pulled toward pool 504, and then immersed in the gallium. The flexibility of the probe facilitates bending / bending to pull the tip into the liquid gallium, and this flexibility assists the interaction of the probe tip with the pool of gallium.

[0091] This causes the reflection of the flexible cantilever probe to change, as in Figure 5B , where the color of the probe appears darker. Thus, when the probe tip enters the liquid metal, the flexible cantilever bends and the light reflection from the cantilever changes as viewed from directly above with an objective lens. This serves as an indication that the probe tip is properly immersed in the liquid metal. Even if the reflected light is not directly above the probe cantilever, it may still be altered by the tip entering the liquid metal. The ripples (506) in the gallium may additionally or alternatively be detected to tell when the probe tip has entered the pool 504. This change may typically be local to the probe tip, as other more distant areas 508 of the liquid may not be sensitive as they are displaced from the probe tip.

[0092] FIG. 6A to FIG. 6B Additional observable changes based on immersion of the probe tip into a liquid conductive material according to aspects described herein are depicted. FIG. 6A to FIG. 6C In each of the figures, the probe tip is presented facing toward the objective of the microscope, and the figure shows a view of the probe tip through the objective. Fig. 6A In FIG. 6 , the probe tip is examined after being immersed in gallium in an environment and under conditions where gallium is liquid at room temperature. The darker rectangular portion 602 is the probe, and an area 606 of coating on the tip extending from the probe arm is identified. The probe tip indicated by the smaller circular area 606 appears a different shade due to the liquid conductive material coating. For higher numerical aperture objectives, Figure 6B The tip can be seen in more detail in . The amorphous material seen on the tip at 610 is the liquid gallium coating. These depictions indicate a high level of control in coating only a small portion of the probe.

[0093] If necessary, the probe can be easily cleaned to remove liquid metal, for example with hydrogen chloride or other solutions. The results of such cleaning are shown in Figure 6C Compare Figure 6B (before cleaning) with Figure 6C (after cleaning), Figure 6C The shape of the tapered probe tip 612 can be clearly seen in FIG. 6 , indicating that the conductive material from the dip has been easily removed.

[0094] Figure 7 Depicted are example test devices and setups for DUT measurement that may incorporate aspects discussed herein. Figure 7 The basic circuitry by which the probes can be connected is shown. It is shown that only one probe 704 is probing the DUT 702 at any given time. The DUT includes contact pads located on a substrate. The substrate incorporates a counter contact at 706.

[0095] Electrical probe 704 may make contact with DUT 702, such as directly or via a liquid metal bridge as described herein, on a conductive pad of the DUT, which is an electronic, optoelectronic, or electromechanical device as some examples. Electrical signal 708 is conducted via connecting cables 710, 712 to resistor 714 and amplifier 716, into ground 718, and via BNC cable 720 to auxiliary input 722, which is within DT box 724, which has an auxiliary output and provides a bias voltage to the second contact 706 on the DUT via bias cable 726. This is just one example environment for applying an electrical signal to the DUT.

[0096] The electrical interaction between the probe and the conductive material (such as the liquid conductive material and the contact pads / points of the DUT) can be tracked using appropriate electronics that can monitor the voltage / current signal. As described, this can be the signal generated when the probe is immersed in the liquid conductive material and / or when electrically coupled to any other conductive surface (such as the contact pad). Fig. 8A An example current-voltage curve is depicted when the probe tip touches a liquid bath or a conductive surface. Plot 802 represents the applied voltage, and plot 804 represents the excitation response (current) measured with a probe tip (e.g., of probe 806) in contact with a conductive material (which is liquid metal or conductive surface 808) or the probe tip in liquid metal bridging its contact with the conductive surface.

[0097] In one example, via Figure 7Schematic diagram of monitoring conductivity. The signal 804 obtained in Fig. 8A Indicated in is the conductivity as a function of time when the probe 806 is in the conductive metal liquid 808. This characterizes the electrical properties of the probe / probe tip in contact with the conductive material, whether it is in direct contact with the DUT or through a liquid metal bridge (e.g., a drop of liquid conductive material) or even directly in the liquid metal. It can be seen that the current indicated by 804 closely follows the applied voltage 804, which means that the signal is good. It should be noted that, as discussed above, the probe geometry can vary, and in some embodiments, each probe can have a different shape as shown in FIG. FIG. 8A to FIG. 8C , in contrast to a probe tip that is narrowed (eg, to a point) as depicted in other examples discussed herein.

[0098] When the probe tip is immersed in a liquid conductive material, the interaction between the tip and the material can be observed by (I) FIG. 5A to FIG. 5B , (ii) monitoring and observing the change in voltage, (iii) or a combination of both to monitor and verify.

[0099] In each of the above conditions (probe touching the bath or contact pad), maintaining this contact can be independent and does not take into account and does not require any feedback. Fig. 8AIn the case of optical monitoring, when monitored with a charge coupled device (CCD), the method is affected by a stepper motor, although the use of a CCD is not necessary for optical monitoring and other automatic or manual methods may be suitable for this method. As shown, the preferred monitoring of contact may be current measurement. In an array of probes, and in the case where optical / mechanical schemes are primarily used to measure contact and leveling of the array, electrical signals may be used in addition or alternatively according to the embodiments described herein. In the absence of feedback, and with or without liquid metal droplets, the application of conductivity simplifies the important operation of "leveling" the probe relative to the contact of the DUT. In this regard, currently applied leveling techniques that do not take into account the conductivity signal require relatively accurate leveling of the probe relative to the DUT. However, a byproduct of enabling the probe to easily make electrical contact (for example, via vacuum coating techniques and / or by dipping the probe into a liquid conductive material) is that the observed conductivity can be used to easily "level" the probe relative to the DUT surface with which the probe is to be contacted. By "leveling" in this context is meant that each probe is aligned with, and in proper electrical communication with, a respective one or more contact pads. Also, electrical conductance can be used to discern which probes are in electrical contact with their respective contact pads, and therefore how to move or tilt the probe array and / or DUT to "level" the probes relative to the DUT. At the same time, the droplet approach more easily achieves electrical contact with greater tolerance for probes of different lengths due to greater deviation in electrical coupling between the droplet and the target conductive pad, e.g., because the thickness of the droplet provides a buffer / deviation / tolerance in terms of probe tip misalignment and / or spacing from the contact pad, yet the probes still each make proper electrical contact with a respective contact pad.

[0100] When using a liquid metal bridge (droplet), the flexibility requirements or characteristics of the cantilever probe may be relaxed, whether or not active feedback is used. For example, the flexibility of the probe may not be as important because the probe itself does not necessarily have to physically touch any contact pads, as the contact of the liquid conductive bag provides the necessary electrical contact. Depending on the size of the bag, a large enough cushion may be created so that the probe tip does not need to touch any conductive pads.

[0101] Furthermore, in probe-to-surface applications, including those for scanning probe conductivity, thermal conductivity, thermocouple imaging, or other applications requiring electrical connections, such liquid metal bridges allow for simplified electrical excitation and both measurement of electricity, heat, conductivity, and imaging. These and other electrical-based phenomena will be greatly simplified due to the features created by such liquid metal bridges. One of the features is excellent and efficient in the necessary electrical contact, protection of the liquid metal and the probe inserted in this liquid inside the resulting thin package from oxidation, and protection of the metal at the tip of the probe from oxidation. In addition to probe arrays, these and other features also solve many of the problems of scanning probe imaging based on electrical interaction with even a single probe.

[0102] Figure 8B Example current-voltage curves and optical properties of the probe are depicted when the probe is coated with gallium and when the probe is held in air before being introduced to a gold surface (e.g., representing the probe having been dipped into liquid metal and then removed from the liquid metal and before the probe contacts a contact point of the DUT). Plot 810 represents the applied voltage and plot 812 represents the excitation response (current) measured with the probe tip. Excitation response 812 is essentially just electrical noise. Meanwhile, probe 814 appears relatively dark. This is consistent with the Figure 8C This contrasts with the uniform, relatively smooth conductive surface of gold that the probe tip 814 contacts (in this case). Figure 8C In , plot 820 is the applied voltage and plot 822 is the current. Figure 8C In addition, the optical indication on the right side of the figure shows that in Figure 8B The probes appear lighter when compared, showing that in addition to the electrical indication of contact (via the waveform), there is also a visual (optical) indication of contact. In this example, each probe makes electrical contact with the metal surface. Fig. 8A The gallium example has more noise in the excitation signal, but Figure 8C The comparison shows the superior conductivity properties of liquid metal relative to the superior conductivity of gold.

[0103] In embodiments involving an array of probes, a separate electrical indication (eg, plot line) may be obtained for each probe of the array to individually assess the electrical coupling state of the probe to a surface (eg, liquid conductive material or contact pad) at that point in time.

[0104] 9A to 9C An example of electrical-based leveling of a probe array according to aspects described herein is depicted. 9A to 9CIn the example, a linear array of probes 902 is provided above a DUT 904 including a plurality of devices to be tested. One purpose may be to level the probes to make substantially uniform contact with a corresponding set of a plurality of devices. In these examples, this occurs in a two-step operation. Each probe may be monitored (e.g., as in FIG. 8A to FIG. 8C ), so that at any given time the electrical properties of the probe can tell whether electrical contact has been made between the probe and the corresponding device of the DUT.

[0105] In this example, the pitch of the probe array (the spacing between adjacent probes) does not exactly match the pitch of the optoelectronic device (e.g., microLED) array, that is, the spacing between adjacent devices. 9A to 9C In any of the above, probes 11, 8, 5 and 2 do not make contact with any contact point. Fig. 9A In , there is no contact between any probe of array 902 and DUT 904. Fig. 9B In FIG. 1 , probes 12, 10, 9, and 7 (most of the upper portion of the probe array) have made contact with respective contact points, as evidenced by the emission (blue luminescence) from the corresponding four microLEDs. Then in FIG. Fig. 9C , probes 6, 4, 3 and 1 have additionally made contact with respective contact points of the DUT to illuminate another 4 microLEDs of the DUT. 9A to 9C This is for illustration purposes only, and in actual applications, the pitch of the probe array may be more aligned with the pitch of the contact points of the DUT, even if testing is performed in multiple scans.

[0106] FIG. 10A to FIG. 10C Continuous excitation when testing a DUT according to aspects described herein is depicted. When testing a DUT with hundreds, thousands, or millions of individual test devices, repeatability is extremely important for efficient testing. Fig. 10A , the probes (numbered 1 to 12) of the probe array 1002 each contact a respective contact pad in the first set of contact pads of the DUT corresponding to the 8 microLEDs (indicated by the 8 boxes) that are lit. Fig. 10B In FIG. 1 , the probes of array 1002 have been lifted out of contact with the first set of contact pads. Fig. 10C , the probes of array 1002 have been brought into contact with a second set of contact pads of the DUT corresponding to the other 8 microLEDs that are illuminated (again indicated by the 8 boxes). In some embodiments, the probes are dipped in a liquid conductive metal ( Fig. 10A ), then as in Fig. 10B As shown in , the probe is lifted or otherwise moved from the first set of contact pads, optionally dipped again in the liquid conductive material, and then as in Fig. 10CIn the embodiment of the present invention, the probes are electrically introduced to the second set of contact pads.

[0107] In one or some specific examples of aspects described herein, a tool and method of using the tool are provided. The tool may be designed to hold a probe tip, or several probe tips parallel to each other as appropriate, and allow the probe tip to flexibly contact a device of interest (e.g., a DUT). The probe tip may have a geometry consistent with the electrical and / or optical and / or mechanical capabilities and / or chemical properties of an element of the device of interest, such that the probe tip can excite such element of the device of interest for a period of time (such as 1 second or less, as an example), and with or without active feedback. This can be achieved while preventing, minimizing or eliminating any risk of contact damage to the probe tip and / or damage to the device of interest, and further, as appropriate, configured to enable / allow other means of optically observing and monitoring the effects of the excitation of the probe tip.

[0108] Optionally, the tool can be constructed using silicon micro / nano fabrication techniques. For example, a probe array / matrix with probe tips can be manufactured at least in part using such fabrication techniques. In an example, photoresists are used to pattern features on a substrate for etching and depositing conductive elements and other features to form integrated circuits or other electronic devices.

[0109] Optionally, the tool may be fabricated from polymer materials and / or materials other than pure or doped silicon, such as silicon nitride or other materials having properties that facilitate efficient fabrication of desired geometries.

[0110] Optionally, the tool allows for multiple excitation and detection paths to be implemented simultaneously. Optionally, a signal detected by contact of the probe tip with the DUT is used to level the carrier of the probe tip relative to the DUT so that several (e.g., all) of the tool's probes are in proper contact with features of the DUT. This may allow leveling to be performed by a signal such as optical reflection from a surface of the tool (e.g., a surface of the tool's probes). In some examples, leveling may be achieved without measuring an electrical property at the probe tip (e.g., current), without excluding this and other means of detecting leveling of the tool relative to the DUT.

[0111] Optionally, the probe tip may be inserted into a conductive material, such as a conductive material in liquid form, to coat at least a portion of the probe (e.g., some or all of the probe tip portion of the probe) to form a droplet thereon. This allows the liquid conductive material in droplet form on the probe tip to be transferred from a bath of liquid conductive material to the DUT without loss of liquid from those droplets on the probe tip. Optionally, this also enables transfer / repositioning / relative movement between the probe tip and the DUT from one or more elements of the device (such as a set of contact pads) to another set of elements of the device (such as another set of contact pads) while maintaining the liquid conductive material, without the need to repeatedly dip the probe tip in the liquid conductive material (when so desired). In an example, the liquid conductive material is or includes a liquid metal.

[0112] The probes may be conductive probes, and there may be a conductive bridge, such as provided by a droplet, between each probe tip and a contact on the DUT, such that the probe tip is not necessarily in direct physical contact with the DUT. For example, the probe tip may be spaced apart from the contacts of the DUT, with a conductive material (conductive material adhered to the probe tip) filling the space between the probe tip and the contacts of the DUT and providing electrical coupling of the probe tip to the contacts of the DUT. Optionally, the conductive material coating the probe tip may be easily removed from the probe tip and the DUT. The introduction of the liquid conductive material to the probe tip and the contacts of the DUT may be temporary, for exciting elements of the DUT (such as microLEDs), i.e., to test / check the desired functionality of such elements of the DUT. As an example, after testing / excitation, the DUT may be removed from the probe, the liquid conductive material cleaned to the necessary extent, and then put into production or used in the manufacture / fabrication of other devices.

[0113] Some features of the aspects described herein are as follows, which may be implemented individually and / or in combination with each other. In a specific example, a method for testing a device under test (DUT) may be provided, the method using a test tool including a plurality of conductive test probes, the DUT including a plurality of contact points associated with a plurality of individual devices in the DUT to be electrically excited. The method may include: positioning the plurality of test probes relative to the plurality of contact points so that the plurality of test probes make electrical contact with the DUT at the plurality of contact points; driving parallel electrical excitation of the plurality of individual devices by one or more electrical signals delivered to the plurality of contact points via the plurality of test probes; and continuously maintaining electrical contact between the plurality of test probes and the plurality of contact points while performing the driving of the parallel electrical excitation. The driving and maintaining may be performed in the absence / without the use of active feedback to continuously maintain electrical contact between the plurality of test probes and the plurality of contact points while performing the driving of the parallel electrical excitation.

[0114] In any of the foregoing and / or alternative embodiments, the method further includes: observing, as part of the positioning, reflected signals from the plurality of test probes as part of the positioning, and confirming that electrical contact has been made between the plurality of test probes and the plurality of contact points based on the observed reflected signals, wherein the actuating is performed in response to the confirmation (based on the confirmation trigger). In an embodiment, the plurality of test probes are configured to be physically attracted to the plurality of contact points based on positioning the plurality of test probes proximate to the plurality of contact points, wherein the reflected signals indicate a force applied to the plurality of test probes, and wherein the confirming is based on observing, based on the reflected signals, that the plurality of test probes have been physically attracted to the plurality of contact points to make electrical contact therebetween.

[0115] In any of the foregoing and / or alternative embodiments, the method further includes: observing light emission from a plurality of individual devices as part of the positioning; and based on the light emission, confirming that electrical contact has been made between a plurality of test probes and a plurality of contact points, wherein driving is performed in response to the confirmation (based on a confirmation trigger).

[0116] In any of the foregoing and / or alternative embodiments, the one or more electrical signals driving the parallel electrical excitations include voltages or currents applied to at least some of the plurality of contact points in parallel with corresponding at least some of the plurality of test probes.

[0117] In any of the foregoing and / or alternative embodiments, the plurality of individual devices includes a plurality of micro light emitting diode (microLED) devices.

[0118] In any of the foregoing and / or alternative embodiments, the plurality of contact points are a first plurality of contact points of the DUT, the plurality of individual devices to be electrically excited are a first plurality of individual devices to be excited, and the method further comprises, after driving the parallel electrical excitation, retrieving / moving the plurality of test probes from / relative to the plurality of contact points, and then positioning the plurality of test probes relative to a next plurality of contact points of the DUT such that the plurality of test probes make electrical contact with the DUT at the next plurality of contact points. In some embodiments, the movement is performed to move the test probes away from the plurality of contact points until contact is established with the next plurality of contact points. In either case, the method may further comprise driving the parallel electrical excitation of a next plurality of individual devices of the DUT by one or more electrical signals delivered to the next plurality of contact points via the plurality of test probes. In embodiments, the method further comprises repeating one or more iterations of retrieving / moving, positioning, and driving such that a plurality of the plurality of individual devices of the DUT are electrically excited via a plurality of the contact points of the DUT.

[0119] In any of the foregoing and / or alternative specific examples, the method may include: immersing at least a portion of each of a plurality of test probes in a liquid conductive material; and removing / moving at least a portion of the immersed each of the test probes from the liquid conductive material, wherein for each of the plurality of test probes, a droplet of liquid conductive material remains on an end of the test probe and is in electrical contact with a conductive portion of the test probe, wherein positioning is performed based on immersion and removal, wherein positioning the plurality of test probes positions the plurality of test probes so that, for each of the plurality of test probes, the liquid conductive material on the end of the test probe makes physical contact with a respective contact point of a plurality of contact points and drives delivery of an electrical signal to the respective contact point via the test probe through the liquid conductive material. In further specific examples, the plurality of contact points are a first plurality of contact points of the DUT, the plurality of individual devices to be electrically excited are a first plurality of individual devices to be excited, and wherein the method further comprises, after driving the parallel electrical excitation, removing / moving a plurality of test probes from / relative to the plurality of contact points, positioning the plurality of test probes relative to a next plurality of contact points of the DUT such that the plurality of test probes make electrical contact with the DUT at the next plurality of contact points, and such that for each of the plurality of test probes, the liquid conductive material on the end of the test probe makes physical contact with a respective next one of the next plurality of contact points. In some examples, the movement is performed to move the test probes away from the plurality of contact points until contact is established with the next plurality of contact points. In either case, the method may further comprise driving the parallel electrical excitation of the next plurality of individual devices of the DUT by one or more electrical signals delivered to the next plurality of contact points via the plurality of test probes. In further embodiments, the method further includes, before positioning the plurality of test probes relative to the next plurality of contact points, repeating immersion and removal from the liquid conductive material and then positioning / moving the plurality of test probes relative to the next plurality of contact points. In some embodiments, this is accomplished while maintaining the amount of conductive material on the ends of the probes.

[0120] In any of the foregoing and / or alternative embodiments, the plurality of test probes comprises an array of test probes having equidistant spacing between the test probes of the array of test probes.

[0121] In any of the foregoing and / or alternative embodiments, a reservoir containing a liquid conductive material provides the liquid conductive material to the ends of the plurality of test probes via one or more conduits / channels / passageways extending to the ends of the plurality of test probes. In a further embodiment, a droplet of the liquid conductive material is formed on the end of each of the plurality of test probes, and wherein the plurality of test probes are positioned such that, for each of the plurality of test probes, the liquid conductive material on the end of the test probe makes physical contact with a respective one of the plurality of contact points, and the actuation delivers an electrical signal to the respective contact point via the droplet of the liquid conductive material on the end of the test probe via the test probe.

[0122] According to another aspect, a method for testing a device under test (DUT) is provided, the method using a test tool including a conductive test probe, the DUT including contact points associated with individual devices of the DUT to be electrically stimulated, the method comprising: positioning the test probe relative to the contact points so that the test probe makes electrical contact with the DUT at the contact points; driving electrical stimulation of individual devices by one or more electrical signals transmitted to the contact points via the test probe; and continuously maintaining electrical contact between the test probe and the contact points while performing the driven electrical stimulation, wherein the driving and maintaining are performed in the absence of / without the need to use active feedback so as to continuously maintain electrical contact between a plurality of test probes and a plurality of contact points while performing the driven parallel electrical stimulation.

[0123] According to a further aspect, a method for testing a device is provided, the method comprising: immersing at least a portion of a conductive test probe of a test device / tool ​​in a liquid conductive material; removing / moving the immersed at least a portion of the test probe from the liquid conductive material, wherein a droplet of the liquid conductive material remains on an end of the test probe and electrically contacts a conductive portion of the test probe; positioning the test probe and a contact point of a device under test (DUT) relative to each other such that the liquid conductive material on the end of the test probe makes physical contact with the contact point on the DUT; and driving excitation of a device of the DUT by an electrical signal delivered to the contact point via the test probe through the droplet of the liquid conductive material on the end of the test probe. In a specific example, the positioning positions the end of the test probe and the contact point relative to each other such that the end of the test probe and the contact point are physically spaced apart, wherein the droplet of the liquid conductive material occupies at least a space between the probe tip of the test probe and the contact point, and electrically bridges the conductive portion of the test probe and the contact point. In such specific examples, the device of the DUT may include a micro light emitting diode (microLED).

[0124] In any of the foregoing and / or alternative embodiments, the liquid conductive material comprises a metal. The metal may include, for example, gallium.

[0125] In any of the foregoing and / or alternative embodiments, at least a portion of the submerged test probe includes at least a portion of a probe tip of the test probe.

[0126] In any of the foregoing and / or alternative embodiments, the contact point is a first contact point, and the method further includes: after driving the excitation, removing / moving the test probe from / relative to the first contact point, wherein after the removal / movement, at least a portion of the droplet of liquid conductive material remains as a droplet on the end of the test probe and remains in electrical contact with the conductive portion of the test probe; positioning the test probe and the next contact point of the DUT relative to each other so that the remaining droplet of liquid conductive material on the end of the test probe is in physical contact with the next contact point of the DUT; and driving the excitation of the next device of the DUT by an electrical signal delivered to the next contact point through the droplet of liquid conductive material on the end of the test probe via the test probe. In some examples, the movement is performed to move the test probe away from the contact point until contact is established with the next contact point.

[0127] In any of the foregoing and / or alternative embodiments, the method iterates one or more times of removing / moving, positioning the test probe and the next contact point relative to each other, and driving the excitation of the next device, wherein at each iteration of iterating the next contact point, the next contact point is a next selected contact point of a next device corresponding to the DUT.

[0128] In any of the foregoing and / or alternative embodiments, the method further includes measuring a signal such as electroluminescence, mechanical deformation, chemical induction, and / or electrical excitation of the device based on the drive excitation.

[0129] In any of the foregoing and / or alternative embodiments, the test probe, the DUT, or both are positioned to move the test probe and the contact point closer to each other.

[0130] In any of the foregoing and / or alternative embodiments, the method further includes monitoring an electrical signal from the test probe, and determining whether electrical contact has been made with the contact point based on the monitored electrical signal.

[0131] In any of the foregoing and / or alternative embodiments, the test probe is a test probe in a test probe array or a plurality of test probes of a test device, and wherein immersion, extraction, positioning, and actuation are performed using each test probe in the test probe array / a plurality of test probes to electrically couple each test probe with a respective contact point of the DUT and drive excitation of a respective device of the DUT. In the embodiment, the method further includes: leveling the test probe array / a plurality of test probes relative to the plurality of devices of the DUT and / or aligning the test probe array / a plurality of test probes with the plurality of devices of the DUT, wherein the leveling / alignment includes monitoring electrical signals from the test probes in the test probe array / a plurality of test probes, and determining whether the test probe array / a plurality of test probes are leveled and / or aligned with the plurality of devices of the DUT based on the monitored electrical signals. In addition, in the embodiment, the method senses, for example in a form based on optical recognition, indicating that continuous contact of the test probe, the test probe array / a plurality of test probes with the DUT is not required and / or monitored. In embodiments, active feedback including automatically moving / physically adjusting at least one of the test probe array / test probes and the DUT to maintain contact of the test probe, test probe array / test probes and the DUT is not required and / or employed.

[0132] In any of the foregoing and / or alternative embodiments, the test probe is manufactured to be inflexible and / or to have a flexibility defined by a selected force constant, which is optionally selected from or within a desired range of values ​​and / or is below a threshold value, an example threshold value being 5 Newton meters.

[0133] In another specific example, a method of preparing a test probe for electrical excitation of a device under test is provided. The preparation includes immersing at least a portion of the test probe in a liquid conductive material, and removing / moving the immersed at least a portion of the test probe from / relative to the liquid conductive material, wherein a droplet of the liquid conductive material remains on an end of the test probe and in electrical contact with a conductive portion of the test probe, wherein during electrical excitation of the device under test, the liquid conductive material at least partially remains in a liquid physical form, or as a malleable solid.

[0134] In yet another specific example, a method of testing a device under test (DUT) is provided, the method comprising: immersing at least a portion of a test probe in a liquid conductive material; removing / moving the immersed at least a portion of the test probe from / relative to the liquid conductive material, wherein a droplet of the liquid conductive material remains at an end of the test probe and is in electrical contact with a conductive portion of the test probe; and introducing the droplet of liquid conductive material on the end of the test probe to a contact point of the DUT, wherein during electrical excitation of a device of the DUT associated with the contact point, the test probe and the contact point remain physically separated, with the liquid conductive material disposed therebetween.

[0135] According to further embodiments, a system for testing a device under test (DUT) is provided, the system comprising an array / several test probes and a liquid conductive material. In embodiments, each test probe in the array / several test probes is manufactured to be non-flexible and / or to have a flexibility defined by a selected force constant, the selected force constant being selected from or within a desired range of values, and / or below a threshold value, an example threshold value being 5 Newton meters. In addition, in some embodiments, a method of using the system comprises: dipping / immersing at least a portion of each test probe in the array / several test probes in the liquid conductive material; removing / moving at least a portion of the immersion of each test probe from / relative to the liquid conductive material, wherein for each test probe in the array / several test probes, the liquid conductive material remains on an end of the test probe and in electrical contact with a conductive portion of the test probe; and moving the array / several test probes and / or the DUT toward / relative to each other so that the liquid conductive material on the end of the test probe makes physical contact with a respective contact point on the DUT while the liquid conductive material at least partially remains in a liquid state.

[0136] The aspects discussed herein, particularly probe arrays, may be related to probe card technology, which provides a collection of probes as a "card" for testing devices. In some specific examples, a probe array as discussed herein may be disposed on / as part of a probe card. A probe card is typically located below a complex circuit system and connected to that complex circuit system to drive / apply voltage through the complex circuit system for testing purposes. The probes of the probe card may protrude upward from the substrate material of the card. The protrusions may be flexible to some extent, and some probes may be longer than other probes. The flexibility may cause the longest protrusion to flex / bend after making physical contact with the DUT until the shorter protrusion makes physical contact with the DUT. A consideration here is to avoid damage to the probe structure. Protrusion bending may result in inaccurate, uneven physical contact of the probe / tip with individual contacts, by which individual components / devices under test are stimulated and measured. The above situation may be particularly problematic in the case where uniform device stimulation is required in various applications ranging from display testing to parallel electrical testing of multiple devices. A method of overcoming the problems associated with inaccurate, uneven contact in making probe arrays is to provide a flexible sample surface, such as a polymer film. Another example of making probe arrays where the sample is flexible is used in a technique known as beam pen nanolithography. Other lithography applications involve coating the probes on the outside with non-conductive liquid inks. However, the use of liquid, highly conductive materials to achieve repeated, soft electrical interactions between the probe tip and the device under test is not discussed. Such coatings will not allow parallel electrical excitation of the device under test as discussed herein, let alone repeated electrical coupling and excitation by the same probe / probe tip on continuous contact.

[0137] While the probe tip itself may be coated with a hard metal coating independent of any of the dipping discussed herein, the purpose of such a coating is typically not to facilitate electrical contact with a surface, but instead to provide an opaque coating around the probe tip in order to facilitate propagation of light in a confined space and close to the sample in the near field.

[0138] Meanwhile, some methods involving the use of feedback experience probes emanating from flexible polymer films on hard sapphire substrates. In these cases, complex feedback methods can be implemented where optical reflection and force microscopy imaging multiple points in parallel can inform feedback motion. One goal is to apply the softest possible touch to measure the force for imaging, rather than, for example, making proper electrical contact with the surface, while achieving the same electrical excitation conditions for the device to be excited in a flexible, equivalent and repeatable manner and without feedback.

[0139] In another approach to parallel feedback, the probe array is conductive and emanates from a flexible polymer and is not touched in parallel, but touched alternately as the sample is scanned under the probe array. As the sample is scanned, the electrical signal obtained in response varies with time, thus forming a time-varying image of the feedback used for imaging. However, this is not effective for the goals of the specific examples herein, such as achieving parallel electrical excitation in a repeatable manner.

[0140] In yet another approach, a massively parallel array of silicon probes is provided with a reservoir for delivering a non-conductive ink, wherein the ink is provided from the reservoir by a channel that delivers the liquid to a standard tip, rather than being applied by immersion / dipping from the outside of the probe. Again, the liquid ink is used for lithography-related applications, rather than device testing, because the ink is non-conductive as described above.

[0141] Some probe designs may incorporate "hollow" glass probes. For example, arrays of hollow glass tubes have been proposed for pen-type nanolithography. One approach may coat the hollow probes and fill the probes with a conductive material to allow for effective conductivity. However, filling such tubes with conductive materials such as liquid metals may be difficult due to the wettability of the liquid metals to the surface of the hollow probes. Chemical modification of such hollow probes or the use of wetting agents may overcome this problem when using parallel hollow probe silicon or similar microfabrication techniques.

[0142] The probes used in conjunction with gallium are hollow glass probes to contain the liquid metal, and such hollow probes containing gallium are used specifically for lithography. In this regard, there are known ways to pressurize gallium into glass pipettes for writing applications. However, both the lithography application and the use of glass probes do not disclose large-scale probe arrays for lithography or, more importantly, electrical excitation and device observation.

[0143] Furthermore, conventional methods utilizing some of the above methods do not provide associated techniques to effectively and efficiently level all of the probes in an array on their respective corresponding contact surfaces. Methods for leveling focus on a flexible joint assembly with a support structure to bring the probe array to a surface and level it. However, according to aspects described herein, conductive droplets provide deviations in conductivity in terms of acceptable distances between the probe tip and the contact surface and the conductivity of the droplet material to enable leveling based on the monitored surface conductivity when desired. Additionally or alternatively, reflection-based leveling may be provided.

[0144] While mechanical leveling may be used in conjunction with aspects described herein, it is not required. The non-conductive nature of the ink that coats the probe externally with past methods of coating the probe does not allow for this; electrical interaction with the surface via the conductivity of the probe tip and the surface has not been used to verify leveling, and other methods (such as active feedback) are used to verify leveling independent of the probe tip surface electrical interaction. Nevertheless, it should be noted that such other methods may be applicable and may be used in conjunction with aspects described herein.

[0145] Therefore, no previous method combines a parallel approach of probe arrays to achieve excellent, similar and repeatable electrical interactions in parallel to effectively excite arrays of devices for testing / inspection applications, such as inspecting microLEDs in displays to achieve electroluminescence-based defect inspection.

[0146] The aspects described herein can reduce the inspection time of a wafer to be inspected. The reduced inspection time can enable the test tool / probe array described herein to be introduced into production / actual applications. As an example, consider a 6-inch microLED wafer where the pitch between contacts is 64.8 microns and there are approximately 4.2 million microLEDs on the wafer. It is also assumed that the probe card has an array of 45×45 probes (i.e., 2025 probes) for driving voltage / current, and is relative to a common ground, and therefore requires approximately 2074 measurements to inspect the microLEDs of the entire wafer (4.2 million microLEDs / 2025 probes = approximately 2074 measurements to inspect its approximately 4.2 million microLEDs). If each measurement (involving 2025 probes testing 2025 microLEDs) takes 1 second, it takes approximately 2074 seconds (0.6 hours) to inspect the microLEDs of the wafer. In a single probe approach to probe each microLED, 4.2 million seconds (about 1.6 months) would be required (by way of example only, and not limitation).

[0147] Apparatus and associated methods / procedures have been described herein. Fig.12An example procedure for testing a sample array comprising individual samples according to aspects described herein is depicted. The method uses a test tool comprising a plurality of conductive test probes. In one or more examples, the procedure can be executed by a processor or processing circuitry of one or more computers / computer systems (such as those described herein, e.g., a computer system of a test tool or a computer system in communication with a test tool).

[0148] Fig.12 The process includes positioning (1202) a plurality of test probes relative to a first plurality of contact points of a sample array, the first plurality of contact points being associated with a first plurality of individual samples of the sample array such that the plurality of test probes make electrical contact with the sample array at the first plurality of contact points. The process drives (1204) parallel electrical excitation of the first plurality of individual samples by one or more electrical signals delivered to the first plurality of contact points via the plurality of test probes, wherein electrical contact between the plurality of test probes and the first plurality of contact points is continuously maintained while driving the parallel electrical excitation of the first plurality of individual samples. The parallel electrical excitation of the first plurality of individual samples produces a first value for testing the first plurality of individual samples. The process determines (1206) whether there are any next plurality of individual samples to be tested. If there are no next plurality of individual samples to be tested (1206, no), the process ends. Otherwise (1206, Y), the process moves (1208) the plurality of test probes relative to the sample array by moving at least one of the plurality of test probes and the sample array such that based on the movement, the plurality of test probes are positioned relative to a next plurality of contact points such that the plurality of test probes make electrical contact with the next plurality of contact points, the next plurality of contact points being associated with a next plurality of individual samples of the sample array. The process further drives (1210) parallel electrical excitation of the next plurality of individual samples by one or more electrical signals delivered to the next plurality of contact points via the plurality of test probes, wherein electrical contact between the plurality of test probes and the next plurality of contact points is continuously maintained while driving the parallel electrical excitation of the next plurality of individual samples. The parallel electrical excitation of the next plurality of individual samples generates a second value for testing the next plurality of individual samples. After driving the excitation of the next plurality of samples, the process may return to 1206 to end or continue with the next set of samples.

[0149] In one embodiment, the individual samples are micro light emitting diode (microLED) devices.

[0150] In some embodiments, driving parallel electrical excitation of the first plurality of individual samples is performed without using active feedback to continuously maintain electrical contact between the plurality of test probes and the first plurality of first contact points while driving parallel electrical excitation of the first plurality of individual samples. This may be applicable to any other individual test samples.

[0151] In a specific example, the procedure further includes observing luminescence from a first plurality of individual samples based on interaction of the plurality of test probes with the first plurality of contact points, and confirming that electrical contact has been made between the plurality of test probes and the first plurality of contact points based on the luminescence, and the driving is performed in response to the confirmation (i.e., can be triggered based on or by the confirmation).

[0152] In a specific example, the procedure further includes: as part of positioning a plurality of test probes relative to a first plurality of contact points, observing reflection signals from the plurality of test probes, and confirming based on the observed reflection signals that electrical contact has been made between the plurality of test probes and the first plurality of contact points, wherein parallel electrical excitation that drives a first plurality of individual samples is performed in response to the confirmation (i.e., can be triggered based on or by the confirmation).

[0153] In one embodiment, at least a portion of each test probe of the plurality of test probes is made of a translucent material.

[0154] In one embodiment, the plurality of test probes comprises an array of test probes, wherein the test probes have equidistant spacing between the test probes of the array of test probes.

[0155] Fig.13 Another example program is described, in this case a program for testing a sample. In one or more examples, the program can be executed by a processor or processing circuit system of one or more computers / computer systems (such as those described herein, such as a computer system of a test tool or a computer system communicating with a test tool).

[0156] At 1302, the process immerses at least a portion of a conductive test probe of a test device in a liquid conductive material and removes the immersed at least a portion of the test probe from the liquid conductive material, wherein based on this, a portion of the liquid conductive material remains on an end of the test probe and is in electrical contact with a conductive portion of the test probe. The process positions (1304) the test probe relative to a contact point of the sample so that the portion of the liquid conductive material on the end of the test probe is in physical contact with the contact point of the sample; and drives (1306) excitation of the sample by an electrical signal delivered to the contact point through the portion of the liquid conductive material on the end of the test probe via the test probe.

[0157] In a specific example, the positioning positions the end of the test probe relative to the contact point so that the end of the test probe is physically spaced apart from the contact point, wherein a portion of the liquid conductive material occupies at least the space between the end of the test probe and the contact point and electrically bridges the conductive portion of the test probe and the contact point.

[0158] In one embodiment, the sample is a micro light emitting diode (microLED) device.

[0159] In one embodiment, the liquid conductive material is metallic. In some such embodiments, the liquid conductive material comprises gallium.

[0160] In a specific example, the procedure further includes monitoring an electrical signal from the test probe, and determining whether electrical contact has been made with the contact point based on the monitored electrical signal.

[0161] In a specific example, the test probe is one of several test probes of a test device, wherein the sample is one of a sample array, and wherein immersion, removal, positioning and driving are performed using each of the several test probes to electrically couple each test probe with a respective contact point of a respective sample of the sample array and drive excitation of the respective sample.

[0162] In some examples, the method or its aspect may be performed by one or more computer systems (e.g., a computer system that controls a device / tool ​​comprising a probe array). For example, the control may control the movement of the tool, the DUT, and / or components of each. The computer system may be incorporated into a portion of the tool / provided as a part of the tool, or may communicate with the tool via one or more communication links, which may be any wired or wireless communication link of a digital / data communication configuration. In some examples, the computer system may be away from the tool. Therefore, the procedures described herein may be performed by one or more computer systems individually or collectively. The computer system may also be referred to as a data processing device / system, a computing device / system / node, or simply a computer. The computer system may be based on one or more of various system architectures and / or instruction set architectures, such as those provided by Intel Corporation (Santa Clara, California, USA) or ARM Holdings Limited (Cambridge, England, UK).

[0163] Fig.14A computer system 1400 is shown communicating with an external device 1412. The computer system 1400 includes one or more processors 1402, such as a central processing unit (CPU). The processor may include functional components used in instruction execution, such as for fetching program instructions from a location such as a cache or main memory, decoding program instructions, and executing program instructions, accessing memory for instruction execution, and writing the results of executing instructions. The processor 1402 may also include temporary registers to be used by one or more of the functional components. The computer system 1400 also includes a memory 1404, an input / output (I / O) device 1408, and an I / O interface 1410, which may be coupled to the processor 1402 and to each other via one or more buses and / or other connections. The bus connection represents one or more of any 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).

[0164] As an example, the memory 1404 may be or include a main memory or system memory (e.g., random access memory) for executing program instructions, a storage device (such as a hard drive, flash media, or optical media, as an example), and / or a cache memory. The memory 1404 may include, for example, a cache memory, such as a shared cache memory, which may be coupled to a local cache memory of the processor 1402 (examples include L1 cache memory, L2 cache memory, etc.). In addition, the memory 1404 may be or include at least one computer program product having a set (e.g., at least one) of program modules, instructions, program codes, or the like, such that the program modules, instructions, program codes, or the like are configured to perform the functions of the embodiments described herein when executed by one or more processors.

[0165] The memory 1404 may store an operating system 1405 and other computer programs 1406, such as one or more computer programs / applications executed to perform the aspects described herein. Specifically, the programs / applications may include computer-readable program instructions that may be configured to perform the functions of the specific examples of the aspects described herein.

[0166] Examples of I / O devices 1408 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 ambient temperature, blood pressure and / or surface 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 viewed as external devices (1412) coupled to the computer system via one or more I / O interfaces 1410.

[0167] Computer system 1400 can communicate with one or more external devices 1412 via one or more I / O interfaces 1410. Example external devices include keyboards, pointing devices, displays, and / or any other device that enables a user to interact with computer system 1400. Other example external devices include any device that enables computer system 1400 to communicate with one or more other computing systems or peripheral devices such as a printer. A network interface / adapter is an example I / O interface that enables computer system 1400 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), providing communication with other computing devices or systems, storage devices, or the like. Ethernet-based (such as Wi-Fi) interfaces and The adapter is only an example of a currently available type of network adapter used in computer systems (BLUETOOTH is a registered trademark of Bluetooth SIG, Inc., of Columbus, Washington, USA).

[0168] Communication between I / O interface 1410 and external device 1412 may occur across a wired and / or wireless communication link 1411, such as an Ethernet-based wired or wireless connection. Example wireless connections include cellular, Wi-Fi, Based on proximity, near field or other types of wireless connections. More generally, the communication link 1411 may be any suitable wireless and / or wired communication link for transmitting data.

[0169] Specific external devices 1412 may include one or more data storage devices that may store one or more programs, one or more computer-readable program instructions and / or data, etc. Computer system 1400 may include and / or be coupled to and communicate with removable / non-removable, volatile / non-volatile computer system storage media (e.g., as an external device to the computer system). For example, it may include and / or be coupled to non-removable, non-volatile magnetic media (typically referred to as a "hard drive"), a disk drive for reading from and writing to a removable, non-volatile magnetic disk (e.g., a "floppy disk"), and / or an optical disk drive for reading from or writing to a removable, non-volatile optical disk (such as a CD-ROM, DVD-ROM, or other optical media).

[0170] The computer system 1400 can operate with numerous other general or special purpose computing system environments or configurations. The computer system 1400 can take any of a variety of well-known examples, including but not limited to a personal computer (PC) system, a server computer system (such as a messaging server), a thin client, a fat client, a workstation, a laptop, a handheld device, a mobile device / computer (such as a smart phone, a tablet, and a wearable device), a multiprocessor system, a microprocessor-based system, a telephone device, a network device (such as an edge device), a virtualization device, a storage controller, a set-top box, a programmable consumer electronic device, a network PC, a microcomputer system, a mainframe computer system, and a distributed cloud computing environment including any of the above systems or devices, and the like.

[0171] The aspects of the present invention may be systems, methods and / or computer program products, any of which may be configured to perform or facilitate the aspects described herein. In some embodiments, the various aspects of the present invention may take the form of a computer program product, which may be embodied as a computer-readable medium. Computer-readable media may be a tangible storage device / media on which computer-readable program codes / instructions are stored. Examples of computer-readable media include, but are not limited to, electronic, magnetic, optical or semiconductor storage devices or systems, or any combination of the foregoing. Examples of computer-readable media include hard disk drives or other mass storage devices, electrical connections with wires, random access memories (RAMs), read-only memories (ROMs), erasable programmable read-only memories such as EPROMs or flash memories, optical fibers, portable computer disks / disks such as compact disk read-only memories (CD-ROMs) or digital versatile disks (DVDs), optical storage devices, magnetic storage devices, or any combination of the foregoing. Computer-readable media may be read by a processor, a processing unit, or the like to obtain data (e.g., instructions) from the media for execution. In certain examples, a computer program product is or includes one or more computer readable media that include / store computer readable program code to provide and facilitate one or more aspects described herein.

[0172] As described, program instructions contained or stored in / on a computer-readable medium may be obtained and executed by any of a variety of suitable components (such as a processor of a computer system) to cause the computer system to operate and work in a particular manner. Such program instructions for performing operations to perform, implement, or facilitate the aspects described herein may be written in any desired programming language, or compiled from program code written in any desired programming language. In some embodiments, such programming languages ​​include object-oriented and / or procedural programming languages, such as C, C++, C#, Java, etc.

[0173] Program code may include one or more program instructions obtained for execution by one or more processors. Computer program instructions may be provided to one or more processors of, for example, one or more computer systems to produce a machine so that the program instructions, when executed by one or more processors, perform, implement or promote aspects of the present invention, such as the actions or functions described in the flowcharts and / or block diagrams described herein. Therefore, in some specific examples, each block or combination of blocks of the flowcharts and / or block diagrams depicted and described herein may be implemented by computer program instructions.

[0174] Although various examples are provided, variations are possible without departing from the spirit of the claimed aspects.

[0175] The terms used herein are for the purpose of describing specific embodiments only and are not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms "comprise" and / or "comprising" when used in this specification specify the presence of stated features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0176] The corresponding structures, materials, actions and equivalents (if any) of all components or steps plus functional elements in the scope of the claims below are intended to include any structure, material or action for performing functions in combination with other claimed elements in the specific claims. The description of one or more specific examples has been presented for the purpose of illustration and description, and is not intended to be exhaustive or limited to the disclosed form presented. For those with ordinary knowledge in the art, many modifications and variations will be obvious. Specific examples are selected and described in order to best illustrate various aspects and practical applications, and to enable those with ordinary knowledge in the art to understand various specific examples with various modifications, so that the modifications are suitable for the intended specific use.

Claims

1. A method for testing a sample array comprising individual samples, the method using a test tool comprising a plurality of conductive test probes, the method comprising: positioning the plurality of test probes relative to a first plurality of contact points of the sample array, the first plurality of contact points being associated with a first plurality of individual samples of the sample array, such that the plurality of test probes make electrical contact with the sample array at the first plurality of contact points; driving parallel electrical excitation of the first plurality of individual samples by one or more electrical signals delivered to the first plurality of contact points through the plurality of test probes, wherein the driving of the parallel electrical excitation of the first plurality of individual samples is performed while electrical contact between the plurality of test probes and the first plurality of contact points is continuously maintained, and wherein the parallel electrical excitation of the first plurality of individual samples produces a first value for testing the first plurality of individual samples; moving the plurality of test probes relative to the sample array by moving at least one of the plurality of test probes and the sample array such that based on the movement, the plurality of test probes are positioned relative to a next plurality of contact points such that the plurality of test probes make electrical contact with the next plurality of contact points associated with a next plurality of individual samples of the sample array; and The parallel electrical excitation of the next plurality of individual samples is driven by one or more electrical signals delivered to the next plurality of contact points via the plurality of test probes, wherein the parallel electrical excitation of the next plurality of individual samples is performed while continuously maintaining the electrical contact between the plurality of test probes and the next plurality of contact points, and wherein the parallel electrical excitation of the first plurality of individual samples produces a second value for testing the next plurality of individual samples.

2. The method of claim 1, wherein the individual samples are micro light emitting diode (microLED) devices.

3. The method of claim 1 , wherein the parallel electrical excitation of driving the first plurality of individual samples is performed without using active feedback to continuously maintain the electrical contact between the plurality of test probes and the first plurality of first contact points while performing the parallel electrical excitation of driving the first plurality of individual samples.

4. The method of claim 1 , further comprising observing luminescence from the first plurality of individual samples based on interaction of the plurality of test probes with the first plurality of contact points, and confirming that the electrical contact has been made between the plurality of test probes and the first plurality of contact points based on the luminescence, wherein the driving is performed in response to the confirmation.

5. The method of claim 1 , further comprising: as part of positioning the plurality of test probes relative to the first plurality of contact points, observing reflected signals from the plurality of test probes, and confirming that electrical contact has been made between the plurality of test probes and the first plurality of contact points based on the observed reflected signals, wherein the parallel electrical excitation that drives the first plurality of individual samples is performed in response to the confirmation. 6 . The method of claim 1 , wherein at least a portion of each of the plurality of test probes is made of a translucent material.

7. The method of claim 1, wherein the plurality of test probes comprises a test probe array, wherein the test probes of the test probe array have equidistant spacing therebetween.

8. A method for testing a sample, the method comprising: immersing at least a portion of a conductive test probe of a test device in the liquid conductive material; removing at least a portion of the immersion of the test probe from the liquid conductive material, wherein a portion of the liquid conductive material remains on an end of the test probe and is in electrical contact with a conductive portion of the test probe; positioning the test probe relative to the contact point of the sample so that the portion of the liquid conductive material on the end of the test probe is in physical contact with the contact point of the sample; and Excitation of the sample is driven by an electrical signal delivered to the contact point via the test probe through the portion of liquid conductive material on the end of the test probe.

9. The method of claim 8, wherein the positioning positions the end of the test probe relative to the contact point so that the end of the test probe is physically spaced apart from the contact point, wherein the portion of the liquid conductive material occupies at least the space between the end of the test probe and the contact point and electrically bridges the conductive portion of the test probe and the contact point.

10. The method of claim 8, wherein the sample is a micro light emitting diode (microLED) device.

11. The method of claim 8, wherein the liquid conductive material is metallic. The method of claim 11 , wherein the liquid conductive material comprises gallium.

13. The method of claim 8, further comprising monitoring an electrical signal from the test probe and determining whether electrical contact has been made with the contact point based on the monitored electrical signal.

14. The method of claim 8, wherein the test probe is one of a plurality of test probes of the test device, wherein the sample is a sample in a sample array, and wherein the immersing, removing, positioning and driving are performed using each of the plurality of test probes to electrically couple each test probe with a respective contact point of a respective sample of the sample array and drive an excitation of the respective sample.

15. An apparatus for testing a device under test, the DUT comprising a plurality of individual devices, the apparatus comprising: Probe array; an alignment system for aligning the DUT and the probe array relative to each other; and a detection system configured to detect signals from the plurality of individual devices; The apparatus is configured to test individual groups of the plurality of devices by scanning electrical contacts of the individual groups of devices while simultaneously driving electrical excitation of the electrical contacts.

16. The apparatus of claim 15, wherein the scanning comprises moving the probe array relative to the DUT by moving at least one of the probe array and the DUT, wherein the movement causes the probe array to contact a respective set of electrical contacts of each respective one of the individual sets of devices.

17. An apparatus as described in claim 16, wherein the movement repeatedly causes the probe array to contact the respective electrical contact sets of each individual device group, wherein the movement causes the probe array to (i) contact one electrical contact set of one individual device group in the individual device groups, then (ii) not contact the one electrical contact set of the one individual device group, and then (iii) contact another electrical contact set of another individual device group in the individual device groups.

18. The apparatus of claim 15, wherein the scanning comprises scanning the DUT beneath the probe array.

19. The apparatus of claim 15, wherein the alignment system is further configured to level the DUT relative to the probe array.

20. The apparatus of claim 15, wherein the signal comprises an optical, electrical, or electrochemical signal from the individual device, and the tool is further configured to detect the optical, electrical, or electrochemical signal using the detection system.

21. A computer system comprising: Memory; and A processor in communication with the memory, wherein the computer system is configured to control a test tool comprising a plurality of conductive test probes to perform a method comprising the steps of: positioning the plurality of test probes relative to a first plurality of contact points of a sample array, the first plurality of contact points being associated with a first plurality of individual samples of the sample array, such that the plurality of test probes make electrical contact with the sample array at the first plurality of contact points; driving parallel electrical excitation of the first plurality of individual samples by one or more electrical signals delivered to the first plurality of contact points through the plurality of test probes, wherein the driving of the parallel electrical excitation of the first plurality of individual samples is performed while electrical contact between the plurality of test probes and the first plurality of contact points is continuously maintained, and wherein the parallel electrical excitation of the first plurality of individual samples produces a first value for testing the first plurality of individual samples; moving the plurality of test probes relative to the sample array by moving at least one of the plurality of test probes and the sample array such that based on the movement, the plurality of test probes are positioned relative to a next plurality of contact points such that the plurality of test probes make electrical contact with the next plurality of contact points associated with a next plurality of individual samples of the sample array; and The parallel electrical excitation of the next plurality of individual samples is driven by one or more electrical signals delivered to the next plurality of contact points through the plurality of test probes, wherein the parallel electrical excitation of the next plurality of individual samples is performed while continuously maintaining electrical contact between the plurality of test probes and the next plurality of contact points, and wherein the parallel electrical excitation of the first plurality of individual samples produces a second value for testing the next plurality of individual samples.

22. The computer system of claim 21, wherein the individual sample is a micro light emitting diode (microLED) device.

23. The computer system of claim 21, wherein the parallel electrical excitation of driving the first plurality of individual samples is performed in the absence of using active feedback to continuously maintain the electrical contact between the plurality of test probes and the first plurality of first contact points while performing the parallel electrical excitation of driving the first plurality of individual samples.

24. The computer system of claim 21, wherein the method further comprises observing luminescence from the first plurality of individual samples based on interaction of the plurality of test probes with the first plurality of contact points, and confirming that the electrical contact has been made between the plurality of test probes and the first plurality of contact points based on the luminescence, wherein the driving is performed in response to the confirmation.

25. The computer system of claim 21 , wherein the method further comprises: observing reflected signals from the test probes as part of positioning the test probes relative to the first plurality of contact points, and confirming that electrical contact has been made between the test probes and the first plurality of contact points based on the observed reflected signals, wherein the parallel electrical excitation that drives the first plurality of individual samples is performed in response to the confirmation.

26. The computer system of claim 21, wherein at least a portion of each of the plurality of test probes is made of a translucent material.

27. The computer system of claim 21, wherein the plurality of test probes comprises a test probe array, wherein the test probes of the test probe array have equidistant spacing therebetween.

28. A computer system comprising: Memory; and A processor in communication with the memory, wherein the computer system is configured to control a test tool comprising a plurality of conductive test probes to perform a method comprising the following steps: immersing at least a portion of a conductive test probe of a test device in the liquid conductive material; removing at least a portion of the immersion of the test probe from the liquid conductive material, wherein a portion of the liquid conductive material remains on an end of the test probe and in electrical contact with a conductive portion of the test probe; positioning the test probe relative to a contact point of a sample so that the portion of the liquid conductive material on the end of the test probe is in physical contact with the contact point of the sample; and Excitation of the sample is driven by an electrical signal delivered to the contact point via the test probe through the portion of liquid conductive material on the end of the test probe.

29. A method as claimed in claim 28, wherein the positioning positions the end of the test probe relative to the contact point so that the end of the test probe is physically separated from the contact point, and wherein the portion of the liquid conductive material occupies at least the space between the end of the test probe and the contact point and electrically bridges the conductive portion of the test probe and the contact point.

30. The computer system of claim 28, wherein the sample is a micro light emitting diode (microLED) device.

31. The computer system of claim 28, wherein the liquid conductive material is metallic.

32. The computer system of claim 31, wherein the liquid conductive material comprises gallium.

33. The computer system of claim 28, wherein the method further comprises monitoring an electrical signal from the test probe, and determining whether electrical contact has been made with the contact point based on the monitored electrical signal.

34. The computer system of claim 28, wherein the test probe is one of a plurality of test probes of the test device, wherein the sample is a sample in a sample array, and wherein the immersion, removal, positioning, and driving are performed using each of the plurality of test probes to electrically couple each test probe with a respective contact point of a respective sample of the sample array and drive excitation of the respective sample.

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