Wafer detector, preparation method thereof and wafer detection circuit

Abstract

The invention provides a wafer detector, a preparation method thereof and a wafer detection circuit, which can be applied to the technical field of wafer detection. The wafer detector comprises a substrate; the plurality of pairs of electrodes are arranged on the substrate along a first direction; wires respectively led out from each of the plurality of pairs of electrodes on the substrate; a cilia structure is arranged on each electrode in the plurality of pairs of electrodes, a conductive layer electrically connected with the corresponding electrode is arranged on the surface of the cilia structure, and when the cilia structure sweeps the electrode to be detected in the MicroLED wafer from the side direction of the electrode to be detected in the second direction, the conductive layer is electrically connected with the electrode to be detected. The cilia structure has rigidity, so that the cilia structure is in electric contact with the to-be-detected electrode through deformation. When the wafer detector is used for detecting the to-be-detected MicroLED wafer, the wafer detector does not need to be pressed down and lifted up repeatedly, and the to-be-detected MicroLED wafer can be measured at a high speed through horizontal movement only by aligning at an initial position once.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wafer detection, and more particularly to a wafer detector, a preparation method thereof and a wafer detection circuit. BACKGROUND

[0002] Micro Light Emitting Diode (Micro LED) can realize image display by self-luminous of micro LED units, has high-precision color and energy-saving advantages, and is widely researched and applied in the display field. After the manufacture of the Micro LED wafer, the electrical performance of the Micro LED in the wafer needs to be detected to ensure that the Micro LED wafer can normally display images.

[0003] In the related art, when the Micro LED in the Micro LED wafer is detected, the probe needs to be controlled to perform the operation of lowering and lifting to realize the contact with the measured Micro LED. After the measurement is completed, the next measurement position needs to be moved to, and after being aligned with the to-be-measured Micro LED, the measurement operation of lowering and lifting is repeated. However, the repeated mechanical displacement and the alignment process greatly increase the measurement time of the Micro LED wafer.

[0004] In addition, in order to pursue the effect of synchronously measuring multiple points, the related art adopts a row-column driving mode to increase the number of measurement points by increasing the number of rows and columns. With the increase of the number of measurement points, the manufacturing cost of the probe, the complexity of the driving circuit and the like will be significantly increased. SUMMARY

[0005] Therefore, the present application provides a wafer detector, a preparation method thereof and a wafer detection circuit.

[0006] According to an aspect of the present application, a wafer detector is provided, comprising: a substrate; a plurality of pairs of electrodes arranged on the substrate along a first direction; 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, the cilium structure having a conductive layer electrically connected with the corresponding electrode on the surface of the cilium structure, wherein the cilium structure is laterally from a to-be-detected electrode in a to-be-detected Micro LED wafer and sweeps the to-be-detected electrode along a second direction intersecting the first direction, and the cilium structure has a rigidity that enables the cilium structure to maintain electrical contact with the to-be-detected electrode by deformation.

[0007] According to an embodiment of the present application, the morphology of the cilium 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 application, the cilia structure comprises: a three-dimensional cilia layer, a stress regulation layer on the three-dimensional cilia layer, and the conductive layer on the stress regulation layer.

[0009] According to an embodiment of the present application, the material of the three-dimensional cilia layer comprises at least one of: 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 regulation layer comprises a parylene polymer; and the material of the conductive layer comprises chromium.

[0010] According to an embodiment of the present application, 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 application, the distribution of the cilia structure on each pair of electrodes arranged in the first direction is the same as the distribution of each pair of to-be-detected electrodes in the to-be-detected Micro LED wafer arranged in the first direction, wherein each pair of to-be-detected electrodes in the to-be-detected Micro LED wafer is the anode and the cathode of a corresponding Micro LED, respectively.

[0012] According to another aspect of the present application, a wafer detector preparation method is provided, comprising: forming a plurality of pairs of electrodes arranged in a first direction on a substrate; forming a wiring respectively leading out from each electrode in the plurality of pairs of electrodes on the substrate; and forming a cilia structure on each electrode in the plurality of pairs of electrodes, the cilia structure having a conductive layer on the surface thereof electrically connected to the corresponding electrode; wherein the cilia structure has a rigidity such that the cilia structure maintains electrical contact with a to-be-detected electrode in a to-be-detected Micro LED wafer by deformation when the cilia structure sweeps across the to-be-detected electrode from the side of the to-be-detected electrode and along a second direction intersecting the first direction.

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

[0014] According to another aspect of the present application, a wafer detection circuit is provided, comprising: the wafer detector as described above; a power supply unit, which is electrically connected to each first electrode of the plurality of pairs of electrodes in the wafer detector respectively, and is configured to supply power to the plurality of pairs of electrodes in the wafer detector in parallel; a collection unit, which is electrically connected to each second electrode of the plurality of pairs of electrodes in the wafer detector respectively, and is configured to collect detection signals output by each second electrode of the plurality of pairs of electrodes in parallel; and a processor, which is configured to determine, according to the detection signals collected by the collection unit, electrical contact states between the cilia structures on the plurality of pairs of electrodes in the wafer detector and corresponding electrode pairs of the MicroLEDs to be detected in the MicroLED wafer to be detected, and determine, according to the detection signals collected by the collection unit, performance parameters of the MicroLEDs to be detected in the MicroLED wafer to be detected, in a case where the cilia structures on the plurality of pairs of electrodes in the wafer detector maintain electrical contact with the corresponding electrode pairs of the MicroLEDs to be detected in the MicroLED wafer to be detected.

[0015] According to an embodiment of the present application, the processor is further configured to, in a case where it is determined that the performance parameter detection of the MicroLEDs to be detected in the nth column of the MicroLED wafer to be detected is completed, control the wafer detector to move by a predetermined distance in the second direction, and detect performance parameters of the MicroLEDs to be detected in an (n+1)th column of the MicroLED wafer to be detected, where the predetermined distance is a distance between the MicroLEDs to be detected in adjacent columns in the second direction, and n is a positive integer.

[0016] According to an embodiment of the present application, the wafer detector can scan the MicroLED wafer to be detected in the second direction. When the cilia structure in the wafer detector collides with the corresponding electrode to be detected in the MicroLED wafer to be detected during movement, the cilia structure can maintain electrical contact with the corresponding electrode to be detected in the MicroLED wafer to be detected by deforming due to the rigidity of the cilia structure, and thus the corresponding MicroLED can be measured. Therefore, when the wafer detector according to the embodiment of the present application is used to detect the MicroLED wafer to be detected, compared with detecting the MicroLED wafer to be detected by using the related art, the wafer detector only needs to be aligned once at the initial position, and then can perform high-speed measurement on the MicroLED wafer to be detected by horizontal movement, without repeated pressing and lifting, thereby improving the measurement throughput. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and other objects, features and advantages of the present application will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which:

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

[0019] Figure 1A A schematic block diagram of a peripheral measurement circuit when detecting a Micro LED array by using a flexible three-dimensional probe array is shown.

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

[0021] Figure 2A A schematic diagram of a wafer detector detecting a wafer to be detected according to an embodiment of the present application is shown.

[0022] Figure 3 A morphological schematic diagram of a cilia structure according to an embodiment of the present application is shown.

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

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

[0025] Figure 6 A schematic block diagram of a wafer detection circuit according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. It should be understood, however, that the description which follows is merely exemplary and is not intended to limit the scope of the application. In the following detailed description of embodiments of the present application, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that one or more embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and functions have not been described in detail in order to avoid obscuring aspects of the present application.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the term "includes" and tautological expressions thereof, such as "including," "includes," "include," "contains," "containing," and so on, mean the term "comprises," unless otherwise noted.

[0028] All terms used herein, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein are defined as having meanings that are consistent with the context of the specification, and should not be interpreted in an idealized or overly formal 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 to disengage from the contact with the electrode of the measured MicroLED wafer. Finally, the mechanical displacement mechanism is moved to the next measurement area, and the probe will repeat the above steps until the measurement of the entire MicroLED wafer is completed.

[0036] In the actual measurement process, this array type probe structure needs to be scanned and measured by point-by-point measurement, so the measurement time will increase with the increase of the number of measurement points. In addition, repeated alignment and pressing and lifting operations will use mechanical displacement mechanisms, and the movement of these mechanisms will further increase the measurement time of the wafer, making it difficult to achieve ultra-high throughput measurement.

[0037] Therefore, the flexible measurement method in the related art uses a patterned silicone base to support a planar extendable electrode array to realize a flexible three-dimensional probe array. These detection electrodes can contact two electrodes on the MicroLED during pressing, and through the deformation of the silicone, the contact between the probe and the MicroLED electrode is ensured. However, as the number of arrays increases, the cumulative error generated during the manufacturing process will also increase, affecting the one-to-one correspondence between the probe and the MicroLED electrode. At the same time, in order to achieve the effect of synchronous measurement of multiple points, the flexible three-dimensional probe array adopts a row-column driving mode, and the number of measurement points is increased by increasing the number of rows and columns. As the number of measurement points increases, the manufacturing cost of the flexible probe, the complexity of the driving circuit, etc. will increase significantly.

[0038] Therefore, whether it is a traditional method or a flexible measurement method, the probe needs to be controlled to perform pressing and lifting operations to achieve contact with the measured MicroLED. After the measurement is completed, it needs to be moved to the next measurement position and aligned with the measured MicroLED, and then the pressing and lifting measurement operations are repeated.

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

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

[0041] As shown in Figure 1B , the peripheral measurement circuit measures the current or voltage of a specific row by applying a voltage to a specific column each time, achieving point-by-point scanning measurement using the 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 can include a substrate 201, a plurality of pairs of electrodes 202 arranged along a first direction (e.g., a horizontal direction in a paper plane) on the substrate 201, wirings 203 respectively leading from each electrode of the plurality of pairs of electrodes 202 on the substrate 201, and a cilia structure 204 on each electrode of the plurality of pairs of electrodes 202. The cilia structure 204 has an electrically conductive layer on a surface thereof electrically connected to the corresponding electrode 202. Figure 2A

[0047] The wirings 203 respectively leading from each electrode of the plurality of pairs of electrodes 202 are external interfaces of the wafer detector 200. The wirings 203 can be arranged in a fan-out manner from the corresponding electrodes 202. The wirings 203 of pairs of electrodes adjacent to each other can be led in different directions to facilitate the arrangement of the wirings 203 while the electrodes 202 are closely arranged. For example, if one electrode is led in a second direction (e.g., a vertical direction in a paper plane) intersecting (e.g., perpendicular to) the first direction, another electrode adjacent to the one electrode in the first direction can be led in another side (e.g., a lower side in Figure 2A Figure 2A Figure 2A The electrodes 202 are arranged in pairs to correspond to anodes and cathodes of MicroLEDs to be detected, for example, in a MicroLED wafer to be detected. Unlike the related art in which a corresponding probe row interface or a probe column interface is led from each row or each column, the wirings 203 can be led from each electrode 202 in the wafer detector according to the embodiments of the present application. Thus, each pair of electrodes can detect corresponding MicroLEDs in parallel. A driving voltage (denoted as V Figure 2A + in the description) can be accessed through the wiring 203 led from the first electrode, and a detection voltage (denoted as V Figure 2A - in the description) corresponding to the electrical performance of the MicroLED can be output through the wiring 203 led from the second electrode.

[0048] According to the embodiments of the present application, since the wafer detector 200 includes the wirings 203 respectively leading from each electrode of the plurality of pairs of electrodes 202 on the substrate 201, the wirings 203 are isolated from each other, and subsequently, the plurality of pairs of electrodes 202 arranged along the first direction on the substrate 201 can be powered in parallel, and the plurality of MicroLEDs corresponding to the plurality of pairs of electrodes 202 can be measured in parallel, thereby improving the detection efficiency compared to the single-point measurement in the related art.

[0049] According to the embodiments of the present application, the wafer detector 200 can be a linear array, and compared to the flexible three-dimensional probe array in the related art, the wafer detector 200 has a simple structure, a low manufacturing cost, and a simpler corresponding driving circuit. ​​​​​

[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 cilium structure 204 on the first electrode in each pair of electrodes 202 can be deformed to maintain electrical contact with the anode of the MicroLED, and the cilium structure 204 on the second electrode can be deformed to maintain electrical contact with the cathode of the MicroLED. The driving voltage can be accessed through a wire leading from the first electrode (indicated by V Figure 2B in the middle of the figure), and the detection voltage corresponding to the electrical property of the MicroLED can be output through a wire leading from the second electrode (indicated by V + in the middle of the figure). Figure 2B - in the middle of the figure).

[0057] With the cilium structure 204 on each pair of electrodes 202 in electrical contact with the corresponding two electrodes to be probed in the MicroLED wafer to be probed, the measurement of the corresponding MicroLED can be achieved by applying a driving voltage to one electrode of the MicroLED wafer to be probed and receiving a measurement voltage (or current) from the other electrode, and the parallel measurement of a whole column of MicroLEDs to be probed can be achieved by cooperating with the corresponding wafer detection circuit, and the measurement of the driving current, light intensity, wavelength and other MicroLED performance parameters can be achieved by cooperating with the corresponding external optical detection system.

[0058] For example, with the cilium structure on each pair of electrodes 202 in electrical contact with the corresponding two electrodes to be probed in the MicroLED wafer to be probed, the detection voltage is a first voltage. With the cilium structure 204 on each pair of electrodes 202 at the gap between the MicroLEDs to be probed in the MicroLED wafer to be probed, the cilium structure 204 recovers from the bending deformation, and the detection voltage is a second voltage. When performing the probing, the wafer probe 200 can be arranged at a certain height from the MicroLED wafer to be probed, so that the top end of the cilium structure 204 is spaced apart from the substrate surface of the MicroLED wafer to be probed in the undeformed state, but the distance is less than the height of the electrodes of the MicroLED relative to the substrate surface of the MicroLED wafer to be probed. In this way, when the cilium structure 204 scans to the MicroLED to be probed on the MicroLED wafer to be probed, the cilium structure 204 will "collide" with the MicroLED to be probed, and thus be deformed to maintain contact with the electrodes of the MicroLED to be probed. On the other hand, when the cilium structure 204 scans to the gap between the MicroLEDs on the MicroLED wafer to be probed, the cilium structure 204 can be separated from the substrate surface of the MicroLED wafer to be probed (or, due to the fluctuation of the profile of the substrate surface of the MicroLED wafer to be probed, the two can be in slight contact with each other).

[0059] ​The first voltage is greater than the second voltage, and the second voltage can be zero or background noise. Therefore, the wafer detection circuit can distinguish whether the voltage signal output from the wiring 203 is the measurement signal of the MicroLED to be detected according to the size of the detection voltage. In this working mode, when the wafer detector is used to detect the MicroLED wafer to be detected, only the first alignment is needed, and the measurement of a whole row of MicroLEDs to be measured can be completed at one time, and the measurement of the whole MicroLED array can be completed through one-way movement. According to the embodiment of the present application, there is no need for complex control logic or circuit for addressing or scanning the MicroLEDs arranged in an array on the MicroLED wafer to be detected.

[0060] It should be noted that the "first voltage" and "second voltage" described herein do not necessarily refer to specific numerical values, but can also be a numerical range. 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 electrode of the wafer detector 200 is in normal electrical contact with the electrode to be detected. The second voltage can be a voltage range other than the first voltage. The predetermined threshold can be determined according to experiments or experience.

[0061] According to the embodiment of the present application, the wafer detector can obtain a MicroLED wafer detection sensor array chip based on the stiffness-adjustable cilium structure by constructing a flexible and conductive cilium structure and a planar electrode array, and realize high-speed and large-volume detection of the MicroLED wafer.

[0062] Figure 3 A schematic diagram of the shape of the cilium structure according to an embodiment of the present application is shown.

[0063] As shown in Figure 3 , the shape of the cilium structure can include one of the following: a cuboid 301, a cylinder 302, a cone 303, a structure formed by stacking pyramids 304, and a structure formed by stacking spheres 305.

[0064] According to the embodiment of the present application, the contact area with the MicroLED wafer to be detected is different when the cilium structure is in different shapes. Since the cilium structure can have various different shapes such as a cuboid, a cylinder, a cone, a structure formed by stacking pyramids, and a structure formed by stacking spheres, it can adapt to different contact area requirements. Moreover, by different shapes, the stiffness of the cilium structure can also be adjusted to regulate the position and intensity of the bending of the cilium structure.

[0065] According to the embodiment of the present application, the shape of the cilium structure can be selected according to the actual required contact area, the position and intensity of the bending of the cilium structure, which is not limited herein.

[0066] According to embodiments of the present application, the wafer probe has a large aspect ratio of the ductile conductive cilium structure. Such a conductive cilium structure can be realized by wrapping different polymer and metal conductive layers outside the three-dimensional cilium layer.

[0067] Figure 4 A partial cross-sectional view of a wafer probe according to embodiments of the present application is shown.

[0068] Figure 4 In the case where the cilium structure is in the form of a cone, Figure 2A A cilium structure on the substrate 201 of the wafer probe 200 in FIG. 1 is shown. As Figure 4 shown, the wafer probe 200 can include a substrate 201, an electrode 202 on the substrate 201, and a wiring 203 leading from the electrode 202, and the cilium structure is disposed on the electrode 202.

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

[0070] The three-dimensional cilium layer 2041 is the base or body of the cilium structure, which has flexibility and ductility. The form of the cilium structure described above in connection with Figure 3 is basically defined by the three-dimensional cilium layer 2041. In other words, the three-dimensional cilium layer 2041 can have a three-dimensional form as described above in connection with Figure 3 .

[0071] According to embodiments of the present application, the material of the three-dimensional cilium layer 2041 can include at least one of the following: a conductive composite material such as a composite material of silicone and silver nanoplate, a composite material of silicone and carbon nanotube, a composite material of polyurethane and silver nanoplate, a composite material of polyurethane and carbon nanotube, and a non-conductive material such as silicone with two-photon absorption curing capability.

[0072] The stress regulation layer 2042 can be used to regulate the stress (or strain) of the cilium structure. The stress regulation layer 2042 can be formed as a polymer film layer, and the material thereof can include, for example, a parylene polymer. The stress regulation layer 2042 can not be conductive. The conductive layer 2043 can be used to realize the desired electrical contact, for example, the electrical contact between the to-be-probed electrode (the Micro LED electrode contacted by the deformation of the cilium structure) and the electrode 202 (and accordingly, the wiring 203 leading from the electrode 202), and the material thereof can include a metal such as chromium.

[0073] According to embodiments of the present application, 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 100 nm, 200 nm, 500 nm, 800 nm, 1000 nm, 2 μm, 5 μm, or 10 μm. The thickness of the conductive layer 2043 can be 20 nm, 50 nm, 60 nm, 80 nm, 90 nm, or 100 nm.

[0075] According to embodiments of the present application, through structural settings (e.g., topography, lamination) of the cilia structure, material selection, processing technology, etc., the cilia structure has a suitable rigidity, which enables the cilia structure to maintain electrical contact (e.g., the contact resistance between them is less than a predetermined threshold) with the corresponding electrode to be detected in the Micro LED wafer to be detected by deforming when the cilia structure is swept from the side of the corresponding electrode to be detected in the Micro LED wafer to be detected along a second direction intersecting the first direction, and does not cause physical damage such as scratching to the Micro LED wafer to be detected.

[0076] According to embodiments of the present application, the cilia structure is composed of a structure and a film of multiple layers of different materials. The core is a three-dimensional cilia layer composed of a polymer material such as silicone, polyurethane, etc. with flexibility and ductility. A stress regulation layer is covered on the material for regulating the overall modulus of the cilia structure, so that it produces different degrees of resilience when it is bent under stress. The conductive layer on the stress regulation layer can be better attached to the surface of the three-dimensional cilia layer through the stress regulation layer, and also has the effect of further regulating the rigidity of the cilia. In addition, by changing the morphology of the cilia structure, such as a cuboid, a cylinder, a cone, a superposition type formed by a plurality of pyramids (i.e., a structure formed by pyramid stacking), a spherical structure superposition type (i.e., a structure formed by sphere stacking), etc., the bending position and intensity of the cilia structure can be regulated.

[0077] In addition to the regulation of resilience that can be achieved by structure, the rigidity gradient of the cilia structure can also be further regulated by the degree of cross-linking of the silicone in the cilia structure, such as changing the ratio of silicone precursor and curing agent, changing the baking temperature, changing the light intensity of ultraviolet cured silicone, etc. Furthermore, the force caused by the resilience of the cilia structure ensures the stable contact of the cilia structure with the electrode of the Micro LED to be detected, and different morphologies of the cilia structure can also provide different contact areas, thereby affecting the contact resistance between the probe and the Micro LED to be detected.

[0078] According to embodiments of the present application, the cilia structure can further include a protective layer covering the conductive layer 2043. The material of the protective layer can include at least one of copper, nickel, and tin.

[0079] According to an embodiment of the present application, the protective layer can improve the durability of the cilia structure to extend the service life of the cilia structure. For example, the protective layer can prevent the cilia structure from being damaged by the to-be-detected electrode, especially when the to-be-detected electrode is relatively hard. In addition, the protective layer can improve the corrosion resistance of the cilia structure to prevent the cilia structure, especially the outermost conductive layer 2043, from being eroded by the external environment.

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

[0081] Figure 5 The wafer detector manufacturing method shown can be used to manufacture the wafer detector described above.

[0082] As shown in Figure 5 The wafer detector manufacturing method can include operations S510-S530.

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

[0084] In operation S520, wires are formed on the substrate and respectively led out from each electrode in the plurality of pairs of electrodes.

[0085] In operation S530, a cilia structure is formed on each electrode in the plurality of pairs of electrodes. The cilia structure has a conductive layer on its surface and the conductive layer is electrically connected to the corresponding electrode.

[0086] The cilia structure has a rigidity that allows the cilia structure to maintain electrical contact with the to-be-detected electrode by deforming when the cilia structure sweeps the to-be-detected electrode from the side of the to-be-detected electrode in a Micro LED wafer and along a second direction intersecting the first direction.

[0087] According to an embodiment of the present application, forming a cilia structure on each electrode in the plurality of pairs of electrodes can include: forming an initial three-dimensional cilia layer on each electrode by a mold method or in-situ three-dimensional printing using a first material; in-situ curing the initial three-dimensional cilia layer to obtain a three-dimensional cilia layer; conformally depositing a polymer on the three-dimensional cilia layer and the wires by a vapor deposition method, and performing local etching on the obtained polymer film to obtain a stress control layer and expose a local area of each electrode that does not overlap with the projection of the three-dimensional cilia layer along the stacking direction and a connection area on the wires for electrical connection with an external detection circuit; and depositing a second material on the stress control layer and the exposed local area of the electrode to obtain a conductive layer.

[0088] For example, a planar thin film circuit corresponding to the electrode size and distribution of the MicroLED to be detected on the MicroLED wafer to be detected can be obtained by a CMOS process on a glass substrate. The planar thin film circuit can include a plurality of pairs of electrodes arranged along a first direction and a wiring respectively leading out from each electrode in the plurality of pairs of electrodes. The electrodes can be circular.

[0089] In the area of each electrode in the planar thin film circuit, a three-dimensional initial cilia layer is prepared by a mold method or in-situ three-dimensional printing. The initial cilia layer can be based on a conductive composite material (for example, a silicone and silver nanoparticle composite material, a silicone and carbon nanotube composite material, or a polyurethane and silver nanoparticle composite material, a polyurethane and carbon nanotube composite material, etc.) or a non-conductive material (for example, a silicone with two-photon absorption curing capability). These materials can be cured in-situ by heating or light excitation to obtain a three-dimensional cilia with elasticity. The rigidity of the final three-dimensional cilia layer can be improved by changing the ratio of silicone precursor and curing agent, changing the baking temperature, changing the light intensity of the ultraviolet curing silicone, etc., thereby affecting the size of the resilience of the three-dimensional cilia layer after deformation.

[0090] Subsequently, a parylene polymer thin film can be conformally deposited on the elastic three-dimensional cilia layer by vapor deposition to regulate the stress and strain of the three-dimensional cilia layer. After local etching of the polymer thin film layer, the wiring for external connection in the planar thin film circuit and the local electrode structure under the cilia structure are exposed.

[0091] Subsequently, a chromium-gold thin film with a thickness of about tens of nanometers to hundreds of nanometers is sputtered on the local electrode structure and the polymer thin film layer as a conductive metal layer, thereby forming a composite structure of silicone as the core, the polymer stress regulation layer, and the metal layer in the cilia structure. In addition, according to the hardness of the MicroLED electrode to be detected, copper, nickel, tin, etc. can be deposited outside the conductive metal layer by electroplating to improve the service life of the cilia structure.

[0092] According to the embodiments of the present application, by constructing a stress regulation layer with adjustable rigidity, conformally covering the three-dimensional cilia layer, the overall modulus of the cilia structure is regulated, so that it produces different degrees of resilience when it is bent under stress. Finally, a metal thin film is deposited outside the stress regulation layer. The metal thin film not only can better adhere to the surface of the three-dimensional cilia layer through the previous stress regulation layer, but also has the effect of further regulating the rigidity of the cilia structure.

[0093] According to the embodiment of the present application, the thickness and type of each layer of material can be pre-designed through finite element analysis. According to the characteristics of the material, different degrees of deformation and contact force are generated to ensure good contact with the MicroLED electrode to be measured. Compared with the traditional flexible sensor probe, the design can effectively reduce the design time and production difficulty of the probe, improve the universality and reliability of the detection equipment, and accelerate the industrialization development of the flexible sensor probe.

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

[0095] As shown in Figure 6 , the wafer detection circuit 600 can include a wafer probe 200, a power supply unit 610, an acquisition unit 620, and a processor 630.

[0096] The power supply unit 610 can be electrically connected to each first electrode of the plurality of pairs of electrodes in the wafer probe 200 respectively. The power supply unit 610 can be configured to supply power to the plurality of pairs of electrodes in the wafer probe 200 in parallel.

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

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

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

[0100] The processor 630 can be configured to determine, according to the detection signals acquired by the acquisition unit 620, the electrical contact states of the cilia structures on the plurality of pairs of electrodes in the wafer probe 200 with the electrode pairs of the corresponding MicroLEDs to be measured in the MicroLED wafer to be detected respectively, and determine, in a case where the cilia structures on the plurality of pairs of electrodes in the wafer probe 200 maintain electrical contact with the electrode pairs of the corresponding MicroLEDs to be measured in the MicroLED wafer to be detected respectively, the performance parameters of the MicroLEDs to be measured in the MicroLED wafer to be detected according to the detection signals acquired by the acquisition unit 620.

[0101] According to an embodiment of the present application, the number of arrays of cilia structures can be much less than the number of probes in a conventional flexible three-dimensional probe array, and there is enough space for layout so that each cilia structure can be driven individually and independently without affecting other cilia structures. Therefore, the conventional point-by-point scanning measurement method can be changed to a parallel scanning measurement method. The design and processing difficulty of the cilia three-dimensional probe chip is greatly reduced. The measurement efficiency is improved and the time for repeated alignment of the probe and the wafer is reduced.

[0102] The processor 630 can also be configured to control the wafer detector 200 to move a predetermined distance in the second direction to detect the performance parameters of the MicroLEDs to be detected in the (n+1)th column of the MicroLED wafer to be detected if it is determined that the detection of the performance parameters of the MicroLEDs to be detected in the nth column of the MicroLED wafer to be detected is completed. The predetermined distance is the distance between the adjacent columns of the MicroLEDs to be detected in the second direction, and n is a positive integer.

[0103] For example, when the detection voltage collected by the collection unit 620 is the first voltage, it can be determined that the cilia structures on the multiple pairs of electrodes in the wafer detector 200 are respectively in electrical contact with the electrode pairs of the corresponding MicroLEDs to be detected in the MicroLED wafer to be detected. When the detection voltage collected by the collection unit 620 is the second voltage, it can be determined that the cilia structures on the multiple pairs of electrodes in the wafer detector 200 are located in the gap between the MicroLEDs to be detected in the MicroLED wafer to be detected.

[0104] In addition, considering that there can be faulty MicroLEDs in a column of MicroLEDs, for the MicroLEDs to be detected in the (n+1)th column of the MicroLED wafer to be detected, if a predetermined proportion of the second electrodes of the multiple pairs of electrodes output the first voltage, it is considered that the wafer detector has been aligned and in electrical contact with the MicroLEDs to be detected in the (n+1)th column, and the MicroLEDs to be detected in this column can be measured. In this case, if the second electrode corresponding to a MicroLED to be detected in the (n+1)th column does not output the first voltage but for example outputs the second voltage, it can be considered that the MicroLED to be detected is faulty.

[0105] According to the embodiment of the present application, the processor only needs to determine the electrical contact state of the cilium structure on each pair of electrodes in the wafer detector with the corresponding pair of electrodes of the to-be-detected Micro LED in the to-be-detected Micro LED wafer according to the detection voltage collected by the collection unit when detecting the first column of to-be-detected Micro LED. When detecting other columns of to-be-detected Micro LED subsequently, it only needs to move in one direction to the column where the to-be-detected Micro LED is located, so as to realize alignment, and then the to-be-detected Micro LED can be directly detected. Thus, only the first alignment is needed, and the measurement of the whole row of to-be-detected Micro LED can be completed through one-way movement.

[0106] According to the embodiment of the present application, the wafer detection circuit can be used to contactively measure the electrical characteristics of the Micro LED wafer based on the cilium structure. Meanwhile, the contact force and area of the cilium structure and the electrode on the Micro LED wafer can be controlled by controlling the material, shape and preparation process of the cilium structure.

[0107] According to the wafer detector provided by the embodiment of the present application, by constructing the conductive cilium structure with different shapes, the mechanical stiffness and bending position of the cilium structure are adjusted through the combination of multiple layers of materials and special structure control, so that the conductive cilium structure can adaptively deform when encountering the contour of the Micro LED wafer surface, and has sufficient elasticity and area to ensure that the cilium structure and the to-be-detected electrode on the Micro LED wafer can realize sufficient contact. The whole row of conductive cilium structures are grown in a one-to-one correspondence with the electrode distribution of the Micro LED wafer, the driving signal and the measurement signal are loaded and exported through the planar thin film circuit on the glass sheet and the conductive cilium structure, and the measurement signal is recorded at high speed, so that whether the cilium structure is on the surface of the to-be-detected electrode of the Micro LED wafer or in the gap between the Micro LED on the Micro LED wafer can be distinguished from the signal. In this working mode, the cilium electrode only needs to be aligned once, and then the measurement of the whole row of Micro LED can be completed through one-way movement. Thus, the structure of the traditional network-shaped three-dimensional electrode is changed.

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

[0109] The above described embodiments of the application have been described. However, these embodiments are merely meant to be illustrative of the present application and not meant to limit the scope of the present application. Although each of the above described embodiments have been described separately, this does not mean that measures from the various embodiments cannot be used advantageously in combination. The scope of the present application is defined by the appended claims of each of the embodiments and their equivalents. Numerous alternatives and modifications will become apparent to those skilled in the art without departing from the scope of the present application.

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. 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.

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 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.

4. The wafer detector according to claim 3, characterized in that, The material of the 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 stress-regulating layer is made of a paraffin polymer; The conductive layer is made of chromium.

5. The wafer detector according to claim 3 or 4, 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.

6. The wafer detector according to claim 3 or 4, characterized in that, 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.

7. A method for fabricating a wafer detector, characterized in that, include: 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.

8. The method according to claim 7, 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.

9. A wafer inspection circuit, characterized in that, include: The wafer detector according to any one of claims 1 to 6; 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.

10. The wafer inspection circuit according to claim 9, 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.

Images