Wafer detector, preparation method thereof and wafer detection circuit

Abstract

The application provides a wafer detector, a preparation method thereof and a wafer detection circuit, and can be applied to the technical field of wafer detection. The wafer detector comprises a substrate, a plurality of pairs of electrodes arranged along a first direction on the substrate, a wiring respectively led out from each electrode in the plurality of pairs of electrodes on the substrate, a cilium structure on each electrode in the plurality of pairs of electrodes, and a conductive layer electrically connected to the corresponding electrode on the surface of the cilium structure. The cilium structure is laterally from a to-be-detected electrode in a to-be-detected Micro LED wafer and is capable of scanning the to-be-detected electrode along a second direction. The stiffness of the cilium structure enables the cilium structure to maintain electrical contact with the to-be-detected electrode through deformation. When the to-be-detected Micro LED wafer is detected by using the wafer detector, repeated pressing and lifting are not required, and only one alignment at an initial position is needed. Through horizontal movement, high-speed measurement can be performed on the to-be-detected Micro LED wafer.

Description

Technical Field

[0001] This invention relates to the field of wafer inspection technology, and more specifically, to a wafer detector, its fabrication method, and a wafer inspection circuit. Background Technology

[0002] MicroLED (Micro Light Emitting Diode) enables image display through the self-illumination of tiny LED units, offering advantages such as high-precision color and energy efficiency, and is widely researched and applied in the display field. After MicroLED wafer manufacturing, the electrical performance of the MicroLEDs needs to be tested to ensure that the MicroLED wafer can display images correctly.

[0003] In related technologies, when testing MicroLEDs on a MicroLED wafer, it is necessary to control the probe to press down and lift up to achieve contact with the MicroLED being tested. After the measurement is completed, it needs to be moved to the next measurement position, aligned with the MicroLED under test, and the pressing down and lifting up measurement operation needs to be repeated. However, the repetitive mechanical displacement and alignment process greatly increases the measurement time of the MicroLED wafer.

[0004] Furthermore, in order to achieve the effect of simultaneous measurement of multiple points, related technologies adopt a row-column driven mode, increasing the number of measurement points by increasing the number of rows and columns. However, as the number of measurement points increases, the manufacturing cost of the probe and the complexity of the drive circuit will increase significantly. Summary of the Invention

[0005] In view of this, the present invention provides a wafer detector, a method for fabricating the same, and a wafer detection circuit.

[0006] According to one aspect of the present invention, a wafer detector is provided, comprising: a substrate; a plurality of pairs of electrodes arranged along a first direction on the substrate; wiring extending from each of the plurality of pairs of electrodes on the substrate; a fibrous structure on each of the plurality of pairs of electrodes, the surface of the fibrous structure having a conductive layer electrically connected to the corresponding electrode, wherein, when the fibrous structure sweeps across the electrode to be detected from the side of the electrode to be detected in the MicroLED wafer to be detected along a second direction intersecting the first direction, the stiffness of the fibrous structure is such that the fibrous structure maintains electrical contact with the electrode to be detected through deformation.

[0007] According to embodiments of the present invention, the morphology of the above-mentioned cilia structure includes one of the following: a cuboid, a cylinder, a cone, a structure formed by stacking pyramids, and a structure formed by stacking spheres.

[0008] According to an embodiment of the present invention, the above-mentioned cilia structure includes: a three-dimensional cilia layer, a stress regulation layer on the three-dimensional cilia layer, and a conductive layer on the stress regulation layer.

[0009] According to embodiments of the present invention, the material of the above-mentioned three-dimensional fibrous layer includes at least one of the following: a composite material of silicone and silver nanosheets, a composite material of silicone and carbon nanotubes, a composite material of polyurethane and silver nanosheets, a composite material of polyurethane and carbon nanotubes, and silicone with two-photon absorption curing capability; the material of the above-mentioned stress regulation layer includes a pyrene polymer; and the material of the above-mentioned conductive layer includes chromium.

[0010] According to an embodiment of the present invention, the thickness of the stress regulation layer is between 100 nm and 10 μm, and the thickness of the conductive layer is between 20 nm and 500 nm.

[0011] According to an embodiment of the present invention, the distribution of the cilia structure on the multiple pairs of electrodes arranged along the first direction is the same as the distribution of the multiple electrodes to be detected arranged along the first direction in the MicroLED wafer to be detected, wherein each of the multiple electrodes to be detected in the MicroLED wafer to be detected is the anode and cathode of the corresponding MicroLED.

[0012] According to another aspect of the present invention, a method for fabricating a wafer detector is provided, comprising: forming a plurality of pairs of electrodes arranged along a first direction on a substrate; forming wirings led out from each of the plurality of pairs of electrodes on the substrate; forming a fibrous structure on each of the plurality of pairs of electrodes, wherein the surface of the fibrous structure has a conductive layer electrically connected to the corresponding electrode; wherein, when the fibrous structure sweeps across the electrode to be detected from the side of the electrode to be detected in the MicroLED wafer to be detected along a second direction intersecting the first direction, the stiffness of the fibrous structure is such that the fibrous structure maintains electrical contact with the electrode to be detected through deformation.

[0013] According to an embodiment of the present invention, forming a fibrous structure on each of the plurality of electrodes comprises: forming an initial three-dimensional fibrous layer on each electrode using a first material by means of a mold method or in-situ three-dimensional printing; curing the initial three-dimensional fibrous layer in-situ to obtain a three-dimensional fibrous layer; conformally depositing a polymer on the three-dimensional fibrous layer and the wiring by means of vapor deposition, and locally etching the obtained polymer film to obtain a stress-regulating layer, exposing a local area in each electrode that does not overlap with the projection of the three-dimensional fibrous layer along the stacking direction and a connection area on the wiring for electrical connection with an external detection circuit; depositing a second material on the stress-regulating layer and the exposed local area of ​​each electrode to obtain the conductive layer.

[0014] According to another aspect of the present invention, a wafer inspection circuit is provided, comprising: the wafer detector described above; a power supply unit electrically connected to the first electrode of each of the plurality of pairs of electrodes in the wafer detector, for supplying power to the plurality of pairs of electrodes in the wafer detector in parallel; an acquisition unit electrically connected to the second electrode of each of the plurality of pairs of electrodes in the wafer detector, for acquiring detection signals output by the second electrodes of each of the plurality of pairs of electrodes in parallel; and a processor, for determining, based on the detection signals acquired by the acquisition unit, the electrical contact state between the fibrous structures on the plurality of pairs of electrodes in the wafer detector and the electrode pairs corresponding to the MicroLEDs to be tested in the MicroLED wafer to be inspected, and, while the fibrous structures on the plurality of pairs of electrodes in the wafer detector maintain electrical contact with the electrode pairs corresponding to the MicroLEDs to be tested in the MicroLED wafer to be inspected, determining the performance parameters of the MicroLEDs to be tested in the MicroLED wafer to be inspected based on the detection signals acquired by the acquisition unit.

[0015] According to an embodiment of the present invention, the processor is further configured to, upon determining that the performance parameter detection of the MicroLED in the nth column of the MicroLED wafer to be detected has been completed, control the wafer detector to move a predetermined distance along the second direction to detect the performance parameter of the MicroLED in the (n+1)th column of the MicroLED wafer to be detected, wherein the predetermined distance is the distance between adjacent columns of MicroLEDs to be detected in the second direction, and n is a positive integer.

[0016] According to an embodiment of the present invention, a wafer detector can scan the MicroLED wafer to be detected along a second direction. When the fibrous structure in the wafer detector encounters the corresponding electrode to be detected in the MicroLED wafer during its movement, due to the rigidity of the fibrous structure, the fibrous structure can deform to maintain electrical contact with the corresponding electrode to be detected in the MicroLED wafer, thereby measuring the corresponding MicroLED. Therefore, when using the wafer detector according to an embodiment of the present invention to detect the MicroLED wafer, compared with the detection of the MicroLED wafer using related technologies, there is no need for repeated pressing and lifting; only one alignment at the initial position is required. The wafer detector can then perform high-speed measurement of the MicroLED wafer by horizontal movement, improving the measurement throughput. Attached Figure Description

[0017] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings.

[0018] Figure 1AA schematic diagram of the structure of a flexible three-dimensional probe array in related technologies is shown.

[0019] Figure 1B A schematic block diagram of the peripheral measurement circuit is shown when using a flexible three-dimensional probe array to detect a MicroLED array.

[0020] Figure 2A A schematic diagram of the structure of a wafer detector according to an embodiment of the present invention is shown.

[0021] Figure 2B A schematic diagram of a wafer detector according to an embodiment of the present invention is shown, which detects a MicroLED wafer to be tested.

[0022] Figure 3 A schematic diagram of the morphology of a ciliary structure according to an embodiment of the present invention is shown.

[0023] Figure 4 A partial cross-sectional view of a wafer detector according to an embodiment of the present invention is shown.

[0024] Figure 5 A flowchart of a wafer detector fabrication method according to an embodiment of the present invention is shown.

[0025] Figure 6 A schematic block diagram of a wafer inspection circuit according to an embodiment of the present invention is shown. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0029] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0030] Traditional methods using rigid probes to measure MicroLED wafers not only result in a limited number of measurement points but also cause damage to the wafer surface and wear on the rigid probes. Therefore, flexible probe arrays represent a potential solution to address the problems encountered in MicroLED wafer inspection.

[0031] Figure 1A A schematic diagram of the structure of a flexible three-dimensional probe array in related technologies is shown.

[0032] like Figure 1A As shown, the related technology mainly achieves a three-dimensional stacked flexible three-dimensional probe array by combining a silicone base and a stretchable detection electrode. The detection electrodes of this flexible three-dimensional probe array correspond one-to-one with the electrodes in a MicroLED wafer and are distributed in a row and column structure with the same dimensions as the MicroLED electrodes. For example, the silicone bases are arranged in a matrix on a substrate in rows and columns, and the detection electrodes are disposed on top of the silicone bases arranged in the matrix. The detection electrodes at the top of each silicone base in each row are electrically connected to each other (e.g., through conductive strips extending along the row direction between adjacent silicone base tops) and led out to the probe row interface; the detection electrodes at the top of each silicone base in each column are electrically connected to each other (e.g., through conductive strips extending along the column direction between adjacent silicone base tops) and led out to the probe column interface.

[0033] In a flexible 3D probe array, the detection electrodes in each row can be electrically connected to the corresponding multiplexer in the driving circuit via the probe row interface, and the detection electrodes in each column can be electrically connected to the corresponding multiplexer in the driving circuit via the probe column interface. Thus, the flexible 3D probe array can be driven by rows and columns using a passive matrix approach.

[0034] When performing MicroLED wafer measurements Figure 1A The flexible 3D probe array shown requires prior alignment with the MicroLED wafer under test. Once the probe and the electrodes on the MicroLED wafer are precisely aligned, the probe is pressed down onto the surface of the MicroLED wafer. The deformation of the silicone base within the probe achieves good contact with the electrodes on the MicroLED wafer. For example... Figure 1A As shown, a pair of probes in the flexible three-dimensional probe array make good contact with the electrodes of the MicroLED through the deformation of the probes under pressure.

[0035] After the measurement is completed, the probe is lifted, disengaging from the electrodes of the MicroLED wafer being measured. Finally, it moves to the next measurement area via a mechanical displacement mechanism. The probe will repeat the above steps until the measurement of the entire MicroLED wafer is completed.

[0036] In actual measurement processes, this array-type probe structure requires scanning measurements point by point, so the measurement time increases continuously with the number of measurement points. In addition, repeated alignment and pressing and lifting operations require mechanical displacement mechanisms, and the movement of these mechanisms further increases the wafer measurement time, making it difficult to achieve ultra-high throughput measurements.

[0037] Therefore, the flexible measurement method in related technologies utilizes a patterned silicone base to support a planar, stretchable electrode array to achieve a flexible three-dimensional probe array. These detection electrodes can contact the two electrodes on the MicroLED during pressing, and the deformation of the silicone ensures contact between the probe and the MicroLED electrodes. However, as the number of arrays increases, the cumulative error generated during manufacturing also increases, affecting the one-to-one correspondence between the probe and the MicroLED electrodes. Furthermore, to achieve simultaneous measurement of multiple points, the flexible three-dimensional probe array adopts a row-column driven mode, increasing the number of measurement points by increasing the number of rows and columns. However, as the number of measurement points increases, the manufacturing cost of the flexible probe and the complexity of the driving circuit will significantly increase.

[0038] Therefore, both traditional and flexible measurement methods require controlling the probe to press down and lift up to achieve contact with the MicroLED being measured. After the measurement is completed, the probe needs to be moved to the next measurement position, aligned with the MicroLED being measured, and the pressing down and lifting up measurement operations need to be repeated.

[0039] Figure 1B A schematic block diagram of the peripheral measurement circuit is shown when using a flexible three-dimensional probe array to detect a MicroLED array.

[0040] Can be used Figure 1B The peripheral measurement circuit shown drives a flexible three-dimensional probe array to scan the MicroLEDs in the MicroLED array point by point.

[0041] like Figure 1B As shown, the peripheral measurement circuit achieves point-by-point scanning measurement by applying voltage to a specific column each time and measuring the current or voltage of a specific row using a probe. Figure 1BA 32×32 array is shown as an example. The peripheral measurement circuit can apply a voltage drive to column p (p is a natural number between 1 and 32) Yp and perform current or voltage measurement on row q (q is a natural number between 1 and 32) Xq, thereby obtaining the measurement result of the detection electrode at the intersection between row q and column p.

[0042] The peripheral measurement circuit sends the voltage output from the analog output terminal of the acquisition card to the voltage amplifier, which then outputs the amplified voltage to the corresponding multiplexer. Figure 1B Multiplexers on the top and bottom sides of the array (column multiplexers) so that the (column) multiplexers, based on the control signals from the control terminal, output the amplified voltage via the probe column interface to the probes in the column of the flexible 3D probe array. (Row) multiplexers ( Figure 1B The multiplexers on the left and right sides of the array output measurement signals (current or voltage signals) from the corresponding probe row interfaces to the analog input of the acquisition card based on the control signals from the control terminal. The acquisition card acquires the output of the (row) multiplexers and the voltage amplified by the voltage amplifier based on the analog input, and outputs it to the computer so that the computer can analyze the electrical performance of the MicroLED in the MicroLED wafer. The control signals of the multiplexers' control terminals come from the control signals output from the digital I / O (Input / Output) terminals of the acquisition card. The voltage output from the analog output terminal of the acquisition card and the control signals output from the digital I / O terminals of the acquisition card are generated based on the signals output from the computer or other control circuits in the peripheral measurement circuit.

[0043] As mentioned above, although flexible 3D probe arrays can achieve a very large number of rows and columns, their measurement method still uses point-to-point scanning, employing multiplexers to switch between rows and columns, measuring only one pair of probes and corresponding parameters of one MicroLED at a time, thus limiting measurement efficiency. Although multiple sets of multiplexers (e.g., Figure 1B The example uses two column multiplexers and two row multiplexers, which can increase the number of measurement points per scan, but this increases circuit cost and requires more complex control logic. Furthermore, the repetitive mechanical displacement and alignment process significantly increases the measurement time for MicroLED wafers.

[0044] In view of this, embodiments of the present invention provide a wafer detector, a method for fabricating the same, and a wafer inspection circuit, which can be applied to the field of wafer inspection technology.

[0045] Figure 2A A schematic diagram of the structure of a wafer detector according to an embodiment of the present invention is shown.

[0046] like Figure 2AAs shown, the wafer detector 200 may include: a substrate 201, and a structure on the substrate 201 along a first direction (e.g., Figure 2A The paper includes multiple pairs of electrodes 202 arranged horizontally within the plane of the paper, wiring 203 extending from each of the multiple pairs of electrodes 202 onto a substrate 201, and a cilia structure 204 on each of the multiple pairs of electrodes 202. The surface of the cilia structure 204 has a conductive layer electrically connected to the corresponding electrode 202.

[0047] Wiring 203 extending from each of the multiple pairs of electrodes 202 serves as the external interface of the wafer detector 200. The wiring 203 can be arranged in a fan-out pattern from the corresponding electrodes 202. Wiring 203 for adjacent electrode pairs can extend in different directions to facilitate the arrangement of wiring 203 while ensuring a close arrangement of electrodes 202. For example, if one electrode extends in a second direction intersecting (e.g., perpendicular to) a first direction (e.g., perpendicular to the first direction),... Figure 2A On one side of the vertical direction within the paper (e.g., Figure 2A If the electrode is led out from the upper side of the first direction, then the other electrode adjacent to this electrode in the first direction can be led to the other side in the second direction (e.g., Figure 2A Electrodes 202 are arranged in pairs to correspond to the electrodes to be detected, such as the anode and cathode of each MicroLED in the MicroLED wafer to be detected. Unlike the related art where corresponding probe row interfaces or probe column interfaces are led out from each row or column, in the wafer detector according to the embodiment of the present invention, corresponding wiring 203 can be led out from each electrode 202. Thus, each pair of electrodes can detect the corresponding MicroLED in parallel. The driving voltage (…) can be connected through the wiring 203 led out from the first electrode. Figure 2A V in Chinese + (represented), by outputting a detection voltage corresponding to the electrical performance of the MicroLED through wiring 203 led out from the second electrode (in) Figure 2A V in Chinese - express).

[0048] According to an embodiment of the present invention, since the wafer detector 200 includes wiring 203 led out from each of the multiple pairs of electrodes 202 on the substrate 201, and the wiring 203 are isolated from each other, it is possible to subsequently power the multiple pairs of electrodes 202 arranged along the first direction on the substrate 201 in parallel, thereby realizing parallel measurement of multiple MicroLEDs corresponding to the multiple pairs of electrodes 202, which improves the detection efficiency compared with the single-point measurement in related technologies.

[0049] According to an embodiment of the present invention, the wafer detector 200 can be a linear array, which has a simpler structure, lower manufacturing cost, and simpler corresponding driving circuit compared to the flexible three-dimensional probe array in related technologies.

[0050] When the cilia structure 204 sweeps across the corresponding probe electrode in the MicroLED wafer from the side and along a second direction intersecting the first direction, the stiffness of the cilia structure 204 allows the cilia structure 204 to maintain electrical contact with the corresponding probe electrode in the MicroLED wafer through deformation.

[0051] For example, the first direction and the second direction can be perpendicular to each other.

[0052] According to an embodiment of the present invention, a wafer detector can scan the MicroLED wafer to be detected along a second direction. When the fibrous structure in the wafer detector encounters the corresponding electrode to be detected in the MicroLED wafer during its movement, due to the rigidity of the fibrous structure, the fibrous structure can deform to maintain electrical contact with the corresponding electrode to be detected in the MicroLED wafer, thereby measuring the corresponding MicroLED. Therefore, when using the wafer detector according to an embodiment of the present invention to detect the MicroLED wafer, compared with the detection of the MicroLED wafer using related technologies, there is no need for repeated pressing and lifting; only one alignment at the initial position is required. The wafer detector can then perform high-speed measurement of the MicroLED wafer by horizontal movement, improving the measurement throughput.

[0053] Figure 2B A schematic diagram of a wafer detector according to an embodiment of the present invention is shown, which detects a MicroLED wafer to be tested.

[0054] like Figure 2B As shown, the ciliary structure 204 can bend after contacting the electrode of the MicroLED to be detected, and bend to different degrees according to the direction of movement of the ciliary structure 204 (i.e., the scanning direction) and the height change of the electrode contour of the MicroLED to be detected, thereby adapting to the electrode contour of the MicroLED to be detected.

[0055] The distribution of the cilia structure on the multiple pairs of electrodes arranged along the first direction in the wafer detector is the same as the distribution of the multiple electrodes to be detected arranged along the first direction in the MicroLED wafer to be detected. Each of the multiple electrodes to be detected in the MicroLED wafer to be detected can be the anode and cathode of the corresponding MicroLED, respectively.

[0056] For example, the cilia structure 204 on the first electrode of each electrode pair 202 can maintain electrical contact with the anode of the MicroLED through deformation, and the cilia structure 204 on the second electrode can maintain electrical contact with the cathode of the MicroLED through deformation. A driving voltage can be connected via wiring led from the first electrode. Figure 2B V in Chinese + (represented) by outputting a detection voltage corresponding to the electrical performance of the MicroLED through wiring led out from the second electrode (in... Figure 2B V in Chinese - express).

[0057] When the fibrous structure 204 on each pair of electrodes 202 is in electrical contact with the corresponding two electrodes to be tested in the MicroLED wafer, the driving voltage is applied to one electrode of the MicroLED wafer to be tested by the fibrous structure 204 and the measurement voltage (or current) is received from the other electrode, so that the measurement of the corresponding MicroLED to be tested can be realized. With the corresponding wafer detection circuit, a whole row of MicroLEDs to be tested can be measured in parallel. In addition, with the corresponding external optical detection system, the performance parameters of MicroLED such as driving current, light intensity and wavelength can be measured.

[0058] For example, when the fibrous structure on each pair of electrodes 202 is in electrical contact with the corresponding two electrodes to be detected in the MicroLED wafer, the detection voltage is the first voltage. When the fibrous structure 204 on each pair of electrodes 202 is located at the gap between the MicroLEDs to be detected on the MicroLED wafer, the fibrous structure 204 recovers from its bending deformation, and the detection voltage is the second voltage. During detection, the wafer detector 200 can be positioned at a certain height above the MicroLED wafer, such that the tip of the fibrous structure 204, in its undeformed state, is spaced apart from the substrate surface of the MicroLED wafer, but the distance is less than the height of the MicroLED electrodes relative to the substrate surface of the MicroLED wafer. Thus, when the fibrous structure 204 scans to the MicroLED to be detected on the MicroLED wafer, the fibrous structure 204 will "collide" with the MicroLED to be detected, and thus deform to maintain contact with the electrodes of the MicroLED to be detected. On the other hand, when the fibrous structure 204 scans to the gap between MicroLEDs on the MicroLED wafer to be detected, the fibrous structure 204 can separate from the substrate surface of the MicroLED wafer to be detected (or, due to the undulation of the substrate surface profile of the MicroLED wafer to be detected, the two may make slight contact with each other).

[0059] The first voltage is greater than the second voltage, which may be zero or background noise. Therefore, the wafer detection circuit can distinguish whether the voltage signal output from wiring 203 is the measurement signal of the MicroLED to be detected based on the magnitude of the detected voltage. In this operating mode, when using a wafer detector to detect the MicroLED wafer to be detected, only the initial alignment is required; a whole row of MicroLEDs to be tested can be measured in one go, and the entire MicroLED array can be measured through unidirectional movement. According to embodiments of the present invention, complex control logic or circuitry for addressing or scanning the MicroLEDs arranged in an array on the MicroLED wafer to be detected is not required.

[0060] It should be noted that the "first voltage" and "second voltage" mentioned here do not necessarily refer to specific values, but can also be a range of values. For example, the first voltage can be a voltage greater than or equal to a predetermined threshold, and the second voltage can be a voltage less than the predetermined threshold. The first voltage can cover the voltage range that can be output when the electrodes of the wafer detector 200 are in normal electrical contact with the electrode to be detected, and the second voltage can be a voltage range outside the first voltage. The predetermined threshold can be determined experimentally or empirically.

[0061] According to embodiments of the present invention, a wafer detector can obtain a MicroLED wafer detection sensor array chip based on a stiffness-adjustable fibrous structure by constructing a flexible and conductive fibrous structure and a planar electrode array, thereby realizing high-speed mass detection of MicroLED wafers.

[0062] Figure 3 A schematic diagram of the morphology of a ciliary structure according to an embodiment of the present invention is shown.

[0063] like Figure 3 As shown, the morphology of the ciliary structure can include one of the following: cuboid 301, cylinder 302, cone 303, structure 304 formed by stacked pyramids, and structure 305 formed by stacked spheres.

[0064] According to embodiments of the present invention, the contact area between the cilia structure and the MicroLED wafer to be probed varies depending on the morphology of the cilia structure. Since the cilia structure can have various shapes, such as cuboids, cylinders, cones, pyramidal structures, and spherical structures, it can adapt to different contact area requirements. Furthermore, by using different shapes, the stiffness of the cilia structure can be adjusted, and the bending position and intensity of the cilia structure can be controlled.

[0065] According to embodiments of the present invention, the morphology of the ciliary structure can be selected based on the actual required contact area, the position and strength of the ciliary structure bending, and is not limited herein.

[0066] According to embodiments of the present invention, a wafer detector has a stretchable conductive capillary structure with a high aspect ratio. This conductive capillary structure can be achieved by coating different polymer and metal conductive layers around a three-dimensional capillary layer.

[0067] Figure 4 A partial cross-sectional view of a wafer detector according to an embodiment of the present invention is shown.

[0068] Figure 4 This illustrates the case where the cilia structure is conical in shape. Figure 2A A fibrous structure on the substrate 201 of the wafer detector 200. For example... Figure 4 As shown, the wafer detector 200 may include a substrate 201, an electrode 202 on the substrate 201, and wiring 203 extending from the electrode 202, with a fibrous structure disposed on the electrode 202.

[0069] The cilia structure may include: a three-dimensional cilia layer 2041, a stress regulation layer 2042 on the three-dimensional cilia layer 2041, and a conductive layer 2043 on the stress regulation layer 2042.

[0070] The three-dimensional ciliary layer 2041 is the base or main body of the ciliary structure, possessing flexibility and extensibility. (The above is combined...) Figure 3 The morphology of the described ciliary structure is essentially defined by the three-dimensional ciliary layer 2041. In other words, the three-dimensional ciliary layer 2041 can have the combination described above. Figure 3 The aforementioned three-dimensional form.

[0071] According to embodiments of the present invention, the material of the three-dimensional fibrous layer 2041 may include at least one of the following: conductive composite materials such as a composite material of silicone and silver nanosheets, a composite material of silicone and carbon nanotubes, a composite material of polyurethane and silver nanosheets, a composite material of polyurethane and carbon nanotubes, and non-conductive materials such as silicone with two-photon absorption curing capability.

[0072] The stress modulation layer 2042 can be used to modulate the stress (or strain) of the cilia structure. The stress modulation layer 2042 can be formed as a polymer thin film layer, and its material may include, for example, a pyrene polymer. The stress modulation layer 2042 may not be conductive. The conductive layer 2043 can be used to achieve desired electrical contacts, such as electrical contacts between the probe electrode (a MicroLED electrode contacted by the cilia structure through deformation) and electrode 202 (and correspondingly, wiring 203 led out from electrode 202), and its material may include metals such as chromium.

[0073] According to an embodiment of the present invention, the thickness of the stress regulation layer 2042 can be between 100 nm and 10 μm, and the thickness of the conductive layer 2043 can be between 20 nm and 500 nm.

[0074] For example, the thickness of the stress regulation layer 2042 can be 100nm, 200nm, 500nm, 800nm, 1000nm, 2μm, 5μm, or 10μm. The thickness of the conductive layer 2043 can be 20nm, 50nm, 60nm, 80nm, 90nm, or 100nm.

[0075] According to embodiments of the present invention, through the structural configuration (e.g., morphology, stacking), material selection, and processing technology of the cilia structure, the cilia structure has suitable stiffness, enabling it to maintain electrical contact with the corresponding probe electrode in the MicroLED wafer through deformation when the cilia structure sweeps across the corresponding probe electrode in the MicroLED wafer from the side along a second direction intersecting the first direction (e.g., the contact resistance between them is less than a predetermined threshold), and without causing physical damage such as scratches to the MicroLED wafer.

[0076] According to embodiments of the present invention, the cilia structure is composed of multiple layers of different materials and films. The core is a three-dimensional cilia layer made of flexible and stretchable polymer materials such as silicone and polyurethane. A stress-regulating layer is applied to this material to regulate the overall modulus of the cilia structure, causing it to generate different degrees of resilience when bent under stress. The conductive layer on the stress-regulating layer allows for better adhesion to the surface of the three-dimensional cilia layer and further regulates the stiffness of the cilia. Furthermore, by changing the shape of the cilia structure, such as cuboids, cylinders, cones, multi-pyramid stacked structures (i.e., structures formed by pyramid stacks), or spherical stacked structures (i.e., structures formed by spherical stacks), the bending position and intensity of the cilia structure can be controlled.

[0077] Besides controlling the rebound force through structural adjustments, the stiffness gradient of the villous structure can be further modulated by varying the degree of silicone cross-linking within the structure, such as changing the ratio of silicone precursor to curing agent, altering the baking temperature, or altering the light intensity of the UV-cured silicone. This ensures stable contact between the villous structure and the electrode of the MicroLED under test, as the force generated by the rebound of the villous structure guarantees this contact. Different villous structure morphologies can also provide different contact areas, thus affecting the contact resistance between the probe and the MicroLED under test.

[0078] According to embodiments of the present invention, the fibrous structure may further include a protective layer covering the conductive layer 2043. The material of the protective layer may include at least one of the following: copper, nickel, and tin.

[0079] According to embodiments of the present invention, the protective layer can improve the durability of the villous structure, thereby extending its service life. For example, the protective layer can prevent damage to the villous structure from the probe electrode, especially when the probe electrode has high hardness. In addition, the protective layer can improve the corrosion resistance of the villous structure, preventing external environmental factors from eroding the villous structure, particularly the outermost conductive layer 2043.

[0080] Figure 5 A flowchart of a wafer detector fabrication method according to an embodiment of the present invention is shown.

[0081] Figure 5 The wafer detector fabrication method shown can be used to fabricate the aforementioned wafer detector.

[0082] like Figure 5 As shown, the wafer detector fabrication method may include operations S510 to S530.

[0083] In operation S510, multiple pairs of electrodes arranged along a first direction are formed on the substrate.

[0084] In operation S520, wiring is formed on the substrate from each of the multiple pairs of electrodes.

[0085] In operation S530, a fibrous structure is formed on each of the multiple pairs of electrodes. The surface of the fibrous structure has a conductive layer that is electrically connected to the corresponding electrode.

[0086] When the cilia structure sweeps across the electrode to be probed from the side of the electrode to be probed in the MicroLED wafer to be probed, and along a second direction intersecting the first direction, the stiffness of the cilia structure allows the cilia structure to maintain electrical contact with the electrode to be probed through deformation.

[0087] According to an embodiment of the present invention, forming a fibrous structure on each of a plurality of pairs of electrodes may include: forming an initial three-dimensional fibrous layer on each electrode using a first material by means of a mold method or in-situ three-dimensional printing; curing the initial three-dimensional fibrous layer in-situ to obtain a three-dimensional fibrous layer; conformally depositing a polymer on the three-dimensional fibrous layer and wiring by means of vapor deposition, and locally etching the obtained polymer film to obtain a stress-regulating layer, and exposing local areas in each electrode that do not overlap with the projection of the three-dimensional fibrous layer along the stacking direction and connection areas on the wiring for electrical connection with external detection circuits; depositing a second material on the stress-regulating layer and the exposed local areas of the electrodes to obtain a conductive layer.

[0088] For example, a planar thin-film circuit corresponding to the electrode size and distribution of the MicroLED under test on the wafer can be fabricated on a glass substrate using CMOS technology. The planar thin-film circuit may include multiple pairs of electrodes arranged along a first direction and wiring led out from each of the multiple pairs of electrodes. The electrodes may be circular.

[0089] In planar thin-film circuits, initial three-dimensional fibrous layers are fabricated in the region of each electrode using a molding method or in-situ 3D printing. These initial three-dimensional fibrous layers can be based on conductive composite materials (such as silicone and silver nanosheets, silicone and carbon nanotubes, or polyurethane and silver nanosheets, polyurethane and carbon nanotubes, etc.) or non-conductive materials (such as silicone with two-photon absorption curing capability). These materials can be cured in-situ by heating or photoexcitation to obtain elastic three-dimensional fibrous layers. The stiffness of the final three-dimensional fibrous layer can be improved by changing the ratio of silicone precursor to curing agent, changing the baking temperature, and changing the light intensity of UV-cured silicone, thereby affecting the magnitude of the resilience force after deformation of the three-dimensional fibrous layer.

[0090] Subsequently, a phenelzine polymer film can be conformally deposited on this elastic three-dimensional fibrous layer using vapor deposition to control the stress and strain of the three-dimensional fibrous layer. After local etching of the polymer film layer, the wiring for external connections in the planar thin-film circuit and the local electrode structure beneath the fibrous structure are exposed.

[0091] Subsequently, a chromium-gold thin film with a thickness of approximately tens to hundreds of nanometers is sputtered onto the local electrode structure and the polymer thin film layer as a conductive metal layer, thereby forming a composite structure in the fibrous structure with silicone as the core, a polymer stress-regulating layer, and multiple stacked metal layers. In addition, depending on the hardness of the MicroLED electrode under test, materials such as copper, nickel, and tin can be deposited on the outside of the conductive metal layer by electroplating to improve the lifespan of the fibrous structure.

[0092] According to an embodiment of the present invention, by constructing a stiffness-controlled stress-regulating layer conformally covering the three-dimensional fibrous layer, the overall modulus of the fibrous structure is controlled, causing it to generate different degrees of resilience when subjected to bending stress. Finally, a metal thin film is deposited outside the stress-regulating layer. This metal thin film not only adheres better to the surface of the three-dimensional fibrous layer through the previous stress-regulating layer, but also further regulates the stiffness of the fibrous structure.

[0093] According to embodiments of the present invention, the thickness and type of each material layer can be pre-designed through finite element analysis. Based on the material properties, different degrees of deformation and contact force are generated to ensure good contact with the MicroLED electrode under test. Compared to traditional flexible sensor probes, this design effectively reduces probe design time and manufacturing difficulty, improves the versatility and reliability of testing equipment, and accelerates the industrialization of flexible sensor probes.

[0094] Figure 6 A schematic block diagram of a wafer inspection circuit according to an embodiment of the present invention is shown.

[0095] like Figure 6 As shown, the wafer detection circuit 600 may include a wafer detector 200, a power supply unit 610, a data acquisition unit 620, and a processor 630.

[0096] The power supply unit 610 can be electrically connected to the first electrode of each of the multiple pairs of electrodes in the wafer detector 200. The power supply unit 610 can be used to supply power to the multiple pairs of electrodes in the wafer detector 200 in parallel.

[0097] For example, the power supply unit 610 can be electrically connected to the wiring led out from each of the first electrodes of the multiple pairs of electrodes in the wafer detector 200, and supply power to the multiple pairs of electrodes in the wafer detector 200 in parallel through the wiring.

[0098] The acquisition unit 620 can be electrically connected to the second electrode of each of the multiple pairs of electrodes in the wafer detector 200. The acquisition unit 620 can be used to acquire detection signals, such as voltage or current, output by the second electrodes of each of the multiple pairs of electrodes in parallel.

[0099] For example, the acquisition unit 620 can be electrically connected to the wiring led out from each of the second electrodes of the multiple pairs of electrodes in the wafer detector 200, and the detection signals output by the second electrodes of each of the multiple pairs of electrodes can be acquired in parallel through the wiring.

[0100] The processor 630 can be used to determine the electrical contact state between the cilia structure on the multiple pairs of electrodes in the wafer detector 200 and the electrode pairs corresponding to the MicroLEDs to be tested in the MicroLED wafer to be detected, based on the detection signals acquired by the acquisition unit 620. And while the cilia structure on the multiple pairs of electrodes in the wafer detector 200 maintains electrical contact with the electrode pairs corresponding to the MicroLEDs to be tested in the MicroLED wafer to be detected, the processor 630 can determine the performance parameters of the MicroLEDs to be tested in the MicroLED wafer to be detected based on the detection signals acquired by the acquisition unit 620.

[0101] According to embodiments of the present invention, the number of arrays of ciliary structures can be far less than the number of probes in traditional flexible 3D probe arrays, thus providing sufficient space for layout. This allows each ciliary structure to be driven individually, without interfering with each other and enabling independent operation. Therefore, the traditional point-by-point scanning measurement method can be transformed into a parallel scanning measurement method. This significantly reduces the design and fabrication difficulty of the ciliary 3D probe chip, improves measurement efficiency, and reduces the time required for repeated probe and wafer alignment.

[0102] The processor 630 can also be used to control the wafer detector 200 to move a predetermined distance along the second direction to detect the performance parameters of the MicroLED in the (n+1)th column of the MicroLED in the wafer after the performance parameter detection of the MicroLED in the nth column of the wafer has been completed. The predetermined distance is the distance between adjacent columns of MicroLEDs in the second direction, and n is a positive integer.

[0103] For example, when the detection voltage acquired by the acquisition unit 620 is a first voltage, it can be determined that the fibrous structures on the multiple pairs of electrodes in the wafer detector 200 are in electrical contact with the electrode pairs corresponding to the MicroLEDs to be tested on the MicroLED wafer to be detected. When the detection voltage acquired by the acquisition unit 620 is a second voltage, it can be determined that the fibrous structures on the multiple pairs of electrodes in the wafer detector 200 are located at the gaps between the MicroLEDs to be tested on the MicroLED wafer to be detected.

[0104] Furthermore, considering the possibility of faulty MicroLEDs within a particular column of MicroLEDs, for the MicroLED under test in the (n+1)th column of the wafer, if a predetermined proportion of the second electrodes in each of the multiple electrode pairs output a first voltage, then the wafer detector is considered aligned and electrically contacted with the MicroLED under test in that (n+1)th column, and measurements can be performed on that column of MicroLEDs. In this case, if the second electrode corresponding to a particular MicroLED under test in the (n+1)th column does not output a first voltage but instead outputs, for example, a second voltage, then that MicroLED under test is considered faulty.

[0105] According to an embodiment of the present invention, when detecting the first column of MicroLEDs under test, the processor only needs to determine the electrical contact state between the fibrous structures on multiple pairs of electrodes in the wafer detector and the corresponding electrode pairs of the MicroLEDs under test in the wafer based on the detection voltage collected by the acquisition unit. When subsequently detecting other columns of MicroLEDs under test, alignment can be achieved simply by moving unidirectionally to the column containing the MicroLED under test, allowing direct detection of the MicroLEDs under test. Thus, with only the first alignment, the measurement of an entire row of MicroLEDs under test can be completed through unidirectional movement.

[0106] According to embodiments of the present invention, the present invention can utilize a wafer detection circuit based on a fibrous structure to measure the electrical properties of a MicroLED wafer through contact. Simultaneously, by controlling the material, morphology, and fabrication process of the fibrous structure, the contact force and area between the fibrous structure and the electrodes on the MicroLED wafer can be adjusted.

[0107] The wafer detector provided by the present invention constructs conductive capillary structures of different shapes. Through multilayer material combinations and special structural control, the mechanical stiffness and bending position of the capillary structures are adjusted, enabling the conductive capillary structures to adaptively deform when encountering the undulating contours of the MicroLED wafer surface. Furthermore, the capillary structures possess sufficient elasticity and area to ensure full contact between the capillary structures and the electrodes to be detected on the MicroLED wafer. A row of conductive capillary structures is grown in a manner corresponding one-to-one with the distribution of MicroLED wafer electrodes. Driving and measurement signals are loaded and derived through planar thin-film circuits on a glass slide and the conductive capillary structures. By recording the measurement signals at high speed, it is possible to distinguish from the signals whether the capillary structure is located on the surface of the electrodes to be detected on the MicroLED wafer or in the gaps between MicroLEDs on the MicroLED wafer. In this operating mode, the capillary electrodes only need to be aligned once, and the measurement of an entire row of MicroLEDs can be completed through unidirectional movement. This changes the traditional structure of a network of three-dimensional electrodes.

[0108] Those skilled in the art will understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention can be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

[0109] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the invention is defined by the appended embodiments and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A wafer detector, characterized in that, include: Base; Multiple pairs of electrodes are arranged along a first direction on the substrate; Wiring extending from each of the plurality of pairs of electrodes on the substrate; Each of the plurality of electrode pairs has a cilia structure on its surface, the surface of which has a conductive layer electrically connected to the corresponding electrode. Wherein, when the cilia structure sweeps across the electrode to be detected from the side of the electrode to be detected in the MicroLED wafer to be detected, and along a second direction intersecting the first direction, the stiffness of the cilia structure allows the cilia structure to maintain electrical contact with the electrode to be detected through deformation. The cilia structure includes: a three-dimensional cilia layer, a stress-regulating layer on the three-dimensional cilia layer, and a conductive layer on the stress-regulating layer; the material of the three-dimensional cilia layer includes at least one of the following: a composite material of silica gel and silver nanosheets, a composite material of silica gel and carbon nanotubes, a composite material of polyurethane and silver nanosheets, a composite material of polyurethane and carbon nanotubes, and silica gel with two-photon absorption curing capability; the material of the stress-regulating layer includes a pyrene polymer; the material of the conductive layer includes chromium. The distribution of the cilia structure on the multiple pairs of electrodes arranged along the first direction is the same as the distribution of the multiple electrodes to be tested arranged along the first direction in the MicroLED wafer to be tested, wherein each of the multiple electrodes to be tested in the MicroLED wafer to be tested is the anode and cathode of the corresponding MicroLED.

2. The wafer detector according to claim 1, characterized in that, The morphology of the cilia structure includes one of the following: a cuboid, a cylinder, a cone, a pyramidal structure, and a spherical structure.

3. The wafer detector according to claim 2, characterized in that, The thickness of the stress regulation layer is between 100nm and 10μm, and the thickness of the conductive layer is between 20nm and 500nm.

4. A method for fabricating a wafer detector, characterized in that, The wafer detector applied to any one of claims 1 to 3 comprises: Multiple pairs of electrodes arranged along a first direction are formed on the substrate; Wiring is formed on the substrate, extending from each of the plurality of pairs of electrodes; A fibrous structure is formed on each of the plurality of pairs of electrodes, and the surface of the fibrous structure has a conductive layer that is electrically connected to the corresponding electrode. When the fibrous structure sweeps across the electrode to be detected from the side of the electrode to be detected in the MicroLED wafer to be detected, and along a second direction intersecting the first direction, the stiffness of the fibrous structure allows the fibrous structure to maintain electrical contact with the electrode to be detected through deformation.

5. The method according to claim 4, characterized in that, The formation of a ciliary structure on each of the plurality of pairs of electrodes includes: Using a mold method or in-situ 3D printing, an initial three-dimensional fibrous layer is formed on each electrode using a first material. The initial three-dimensional fibrous layer is cured in situ to obtain a three-dimensional fibrous layer. A polymer is conformally deposited on the three-dimensional fibrous layer and the wiring by vapor deposition, and the resulting polymer film is locally etched to obtain a stress-modulated layer, exposing local areas in each electrode that do not overlap with the projection of the three-dimensional fibrous layer along the stacking direction, as well as connection areas on the wiring for electrical connection with external detection circuits. A second material is deposited on the stress-regulating layer and the local area where each electrode is exposed to obtain the conductive layer.

6. A wafer inspection circuit, characterized in that, include: The wafer detector according to any one of claims 1 to 3; The power supply unit is electrically connected to the first electrode of each of the multiple pairs of electrodes in the wafer detector, and is used to supply power to the multiple pairs of electrodes in the wafer detector in parallel. The acquisition unit is electrically connected to the second electrode of each of the multiple pairs of electrodes in the wafer detector, and is used to acquire the detection signals output by the second electrode of each of the multiple pairs of electrodes in parallel. The processor is configured to determine, based on the detection signals acquired by the acquisition unit, the electrical contact state between the cilia structures on multiple pairs of electrodes in the wafer detector and the corresponding electrode pairs of the MicroLED to be tested in the MicroLED wafer to be detected, and, while maintaining electrical contact between the cilia structures on multiple pairs of electrodes in the wafer detector and the corresponding electrode pairs of the MicroLED to be tested in the MicroLED wafer to be detected, determine the performance parameters of the MicroLED to be tested in the MicroLED wafer to be detected based on the detection signals acquired by the acquisition unit.

7. The wafer inspection circuit according to claim 6, characterized in that, The processor is further configured to, upon determining that the performance parameters of the MicroLED under test in the nth column of the MicroLED wafer under test have been detected, control the wafer detector to move a predetermined distance along the second direction to detect the performance parameters of the MicroLED under test in the (n+1)th column of the MicroLED wafer under test, wherein the predetermined distance is the distance between adjacent columns of MicroLED under test in the second direction, and n is a positive integer.

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