Wafer inspection system and object inspection method

Abstract

A wafer inspection system according to an embodiment includes: a first image sensor that is configured to inspect a wafer loaded on a stage and photographs one surface of the wafer a plurality of times; a second image sensor that photographs the opposite surface of the wafer a plurality of times; and a control unit that controls a time point at which the wafer is photographed, by applying a photographing signal to each of the first image sensor and the second image sensor, wherein each of the first image sensor and the second image sensor is relatively moved in a first direction with respect to the stage, and the relative movement may be continuously performed in a process in which each of the first image sensor and the second image sensor photographs the wafer a plurality of times.

Description

Wafer inspection system and object inspection method

[0001] Exemplary embodiments relate to a wafer inspection system and a method for inspecting an object.

[0002] In a wafer inspection system, a wafer inspection system capable of inspecting each of a plurality of dies can be provided.

[0003] In the method of examining a target, a specific area of ​​the target can be examined by photographing one side and the opposite side of the target and providing a composite image.

[0004] We aim to provide a wafer inspection system with excellent capability to process wafers per hour.

[0005] We aim to provide a method for examining a large number of subjects per hour.

[0006] A wafer inspection system according to an exemplary embodiment is configured to inspect a wafer loaded on a stage, and includes a first image sensor for photographing one side of the wafer multiple times; a second image sensor for photographing the opposite side of the wafer multiple times; and a control unit for controlling a time point for photographing the wafer by applying a photographing signal to each of the first image sensor and the second image sensor; wherein each of the first image sensor and the second image sensor moves relative to the stage in a first direction, and the relative movement can be continuously performed during a process in which each of the first image sensor and the second image sensor photographs the wafer multiple times.

[0007] The wafer includes a plurality of dies arranged in the first direction, the first image sensor can obtain a first image for a division area that divides each of the dies, and the second image sensor can obtain a second image for an inspection area corresponding to the division area.

[0008] A marking pattern is arranged in the inspection area, and the control unit can provide a third image in which the first image and the second image are superimposed so as to inspect the quality of the marking pattern for each of the dies.

[0009] The control unit can control a signal applied to each of the first image sensor and the second image sensor so that the centers of the first image and the second image coincide within the third image.

[0010] The control unit may apply a positive offset to a first signal applied to the first image sensor to delay the time of acquiring the first image when the center of the first image is spaced apart in the first direction relative to the center of the second image within the third image, or apply a negative offset to a second signal applied to the second image sensor to advance the time of acquiring the second image, thereby matching the centers of the first image and the second image.

[0011] The control unit may apply a positive offset to a second signal applied to the second image sensor to delay the time of acquiring the second image when the center of the second image in the third image is spaced apart in the first direction relative to the center of the first image, or may apply a negative offset to a first signal applied to the first image sensor to advance the time of acquiring the first image, thereby matching the centers of the first image and the second image.

[0012] The wafer includes a plurality of inspection rows for the plurality of dies, each of which is arranged in the first direction, and the plurality of inspection rows are arranged in a row in a second direction intersecting the first direction, and relative movement in the first direction and a third direction opposite to the first direction sequentially occurs between each of the first image sensor and the second image sensor and the stage, so that the plurality of inspection rows can be photographed.

[0013] The first image and the second image acquired by the first image sensor and the second image sensor may be image information for individual dies constituting the plurality of dies.

[0014] A method for inspecting an object according to an exemplary embodiment includes: a step of loading an object onto a stage; a step of obtaining a reference image of the object by allowing a first image sensor and a second image sensor, which are arranged to face each other with respect to the stage, to move in a first direction relative to the stage and capture the object multiple times; a step of superimposing a first reference image obtained by the first image sensor and a second reference image obtained by the second image sensor to determine whether they are synchronized; and a step of synchronizing the first reference image and the second reference image by controlling a capturing time point of the first image sensor or the second image sensor; wherein, in the step of obtaining a reference image of the object, the relative movement provided to each of the first image sensor and the second image sensor with respect to the stage may be continuously performed.

[0015] In the step of determining whether the above synchronization is present, it can be determined whether the centers of the first reference image and the second reference image are identical.

[0016] In the step of synchronizing the first reference image and the second reference image, if the center of the first reference image is spaced apart in the first direction with respect to the center of the second reference image, the centers of the first reference image and the second reference image can be aligned by delaying the capturing time of the first image sensor.

[0017] In the step of synchronizing the first reference image and the second reference image, if the center of the second reference image is spaced apart in the first direction with respect to the center of the first reference image, the centers of the first reference image and the second reference image can be aligned by delaying the capturing time of the second image sensor.

[0018] The above object is a wafer including a plurality of dies, the first reference image provides information about a distinguishing area that can distinguish each of the dies, and the second reference image can provide information about an inspection area corresponding to the distinguishing area.

[0019] A marking pattern is arranged in the inspection area, and the second reference image can provide information on the marking quality of each of the dies.

[0020] A wafer inspection system according to an exemplary embodiment discloses a first image sensor and a second image sensor capable of continuous relative movement with respect to a stage when photographing a wafer.

[0021] A wafer inspection system according to an exemplary embodiment discloses a control unit capable of controlling multiple points of time for photographing a wafer by applying photographing signals to each of a first image sensor and a second image sensor.

[0022] A wafer inspection system according to an exemplary embodiment discloses a wafer inspection system capable of reducing misalignment due to physical errors between first and second images acquired by a first image sensor and a second image sensor.

[0023] A wafer inspection system according to an exemplary embodiment discloses a wafer inspection system having excellent capability of processing wafers per hour.

[0024] Figure 1 is a front view of a wafer inspection system according to an exemplary embodiment.

[0025] FIG. 2 is a plan view of a wafer inspection system according to an exemplary embodiment.

[0026] FIG. 3 is a rear view of a wafer inspection system according to an exemplary embodiment.

[0027] FIG. 4 is a graph showing a first signal applied by a control unit to a first image sensor according to an exemplary embodiment.

[0028] FIG. 5 is a drawing showing a first image according to an exemplary embodiment.

[0029] FIG. 6 is a graph showing a second signal applied by a control unit to a second image sensor according to an exemplary embodiment.

[0030] Figure 7 is a drawing showing a second image according to an exemplary embodiment.

[0031] FIG. 8 is a drawing showing a third image according to an exemplary embodiment.

[0032] FIG. 9 is a drawing showing a third image according to an exemplary embodiment.

[0033] FIG. 10 is a graph showing a first signal and a second signal applied by a control unit to each of a first image sensor and a second image sensor according to an exemplary embodiment.

[0034] Fig. 11 is a drawing showing a third image according to an exemplary embodiment.

[0035] FIG. 12 is a graph showing a first signal and a second signal applied by a control unit to each of a first image sensor and a second image sensor according to an exemplary embodiment.

[0036] Figure 13 is a plan view of a wafer inspection system according to an exemplary embodiment.

[0037] Figure 14 is a plan view of a wafer inspection system according to an exemplary embodiment.

[0038] Figure 15 is a plan view of a wafer inspection system according to an exemplary embodiment.

[0039] Fig. 16 is a drawing showing a method for inspecting a target according to an exemplary embodiment.

[0040] Hereinafter, exemplary embodiments will be described in detail with reference to the attached drawings. In the drawings below, the same reference numerals denote the same components, and the sizes of each component in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the embodiments described below are merely exemplary, and various modifications are possible from these embodiments. Hereinafter, the terms "upper" or "upper" may include not only those directly above, below, left, or right in contact, but also those directly above, below, left, or right in non-contact. The singular expression includes the plural expression unless the context clearly indicates otherwise. Furthermore, when a part is said to "include" a component, this does not exclude other components, but rather includes other components, unless specifically stated otherwise. The use of the term "above" and similar referential terms may apply to both the singular and plural. Unless the order of steps constituting a method is explicitly stated or contradicted, these steps may be performed in any suitable order, and are not necessarily limited to the order described. In addition, terms such as "unit", "module", etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software, or a combination of hardware and software. The lines connecting or connecting members between components illustrated in the drawings are merely representative of functional connections and / or physical or circuit connections, and may be represented as various functional connections, physical connections, or circuit connections that are replaceable or additional in an actual device. The use of all examples or exemplary terms is merely for the purpose of describing the technical idea in detail, and the scope is not limited by such examples or exemplary terms, unless otherwise defined by the claims.Hereinafter, a wafer inspection system and a target inspection method according to an exemplary embodiment will be described in more detail.

[0041] FIG. 1 is a front view of a wafer inspection system according to an exemplary embodiment. FIG. 2 is a plan view of a wafer inspection system according to an exemplary embodiment. FIG. 3 is a rear view of a wafer inspection system according to an exemplary embodiment.

[0042] Referring to FIGS. 1 to 3, a wafer inspection system (1) according to an exemplary embodiment can be configured to inspect a wafer (10) loaded on a stage (3). The wafer (10) can be loaded on the stage (3), and the stage (3) can support the wafer (10). The stage (3) can expose one side (11) and the opposite side (12) of the wafer (10). The stage (3) supports the outer surface of the wafer (10) and can expose the one side (11) and the opposite side (12) of the wafer (10), but is not limited thereto. For example, the stage (3) can expose the one side (11) and the opposite side (12) of the wafer (10) by including a transparent material.

[0043] A wafer inspection system (1) according to an exemplary embodiment may include a first image sensor (4). The first image sensor (4) may be disposed on top of a wafer (10). The first image sensor (4) may be configured to photograph one side (11) of the wafer (10). The first image sensor (4) may be, but is not limited to, a vision sensor that receives wavelengths in the visible light range.

[0044] A wafer inspection system (1) according to an exemplary embodiment may include a second image sensor (5). The second image sensor (5) may be disposed on top of a wafer (10). The second image sensor (5) may be configured to photograph one side (11) of the wafer (10). The second image sensor (5) may be a vision sensor that receives wavelengths in the visible light range, but is not limited thereto.

[0045] A wafer inspection system (1) according to an exemplary embodiment may include a control unit (6). The control unit (6) may apply a photographing signal to each of the first image sensor (4) and the second image sensor (5). The control unit (6) may control a time point at which the first image sensor (4) photographs a wafer (10) by applying the photographing signal to the first image sensor (4). The control unit (6) may control a time point at which the first image sensor (4) photographs a wafer (10) by applying a first signal (61) to the first image sensor (4). The first image sensor (4) may receive the first signal (61) applied by the control unit (6) to photograph the wafer (10). The control unit (6) may control a time point at which the second image sensor (5) photographs the wafer (10) by applying a signal to the second image sensor (5). The control unit (6) can control the timing at which the second image sensor (5) photographs the wafer (10) by applying a second signal (62) to the second image sensor (5). The second image sensor (5) can photograph the wafer (10) by receiving the second signal (62) applied by the control unit (6). A specific method by which the control unit (6) controls the photographing timing of the first image sensor (4) and the second image sensor (5) will be described later.

[0046] According to an exemplary embodiment, a wafer inspection system (1) can cause relative movement in a first direction (D1) between the first image sensor (4) and the second image sensor (5) and the stage (3). Here, the first direction (D1) may mean any direction crossing the wafer (10). In addition, the relative movement in the first direction (D1) may be formed by each of the first image sensor (4) and the second image sensor (5) moving in the first direction (D1), but is not limited thereto. For example, the relative movement in the first direction (D1) may be provided by the stage (3) moving in a direction opposite to the first direction (D1) while the first image sensor (4) and the second image sensor (5) are fixed. However, the method of forming the relative movement for the stage (3) provided to each of the first image sensor (4) and the second image sensor (5) is not limited thereto, and for example, the relative movement may be provided by each of the first image sensor (4), the second image sensor (5) and the stage (3) moving.

[0047] In a wafer inspection system (1) according to an exemplary embodiment, a wafer (10) may be fixedly positioned on a stage (3). When each of the first image sensor (4) and the second image sensor (5) is provided with relative movement in a first direction (D1) with respect to the stage (3), each of the first image sensor (4) and the second image sensor (5) may be provided with relative movement in the first direction (D1) with respect to the wafer (10). In the following description, in order to avoid excessive redundancy, it will be described on the assumption that each of the first image sensor (4) and the second image sensor (5) forms relative movement with respect to the wafer (10) by moving in the first direction (D1). However, it will be readily understood by those skilled in the art that the above-described relative movement may also be provided by movement of the stage (3).

[0048] Meanwhile, the wafer (10) may include a plurality of dies (2) arranged in a first direction (D1). Each of the dies (2) may constitute a semiconductor device, but is not limited thereto. A scribe line may be arranged on one side (11) of the wafer (10) to mutually distinguish adjacent dies (2). Each die (2) may be separated from the wafer (10) along the scribe line in a dicing process, but a detailed description thereof will be omitted. A scribe line surrounding each of the dies (2) may be arranged on one side (11) of the wafer (10), and the scribe line surrounding each of the dies (2) may form a distinction area (21) that distinguishes each of the dies (2). In other words, the scribe line arranged on one side (11) of the wafer (10) can define a dividing area (21) that separates each die (2). To understand it the other way around, by observing the dividing area (21) arranged on one side (11) of the wafer (10), the position at which each die (2) is arranged on the wafer (10) can be determined.

[0049] In addition, an inspection area (22) corresponding to the division area (21) may be arranged on the opposite side (12) of the wafer (10). The inspection area (22) may be an area where inspection is performed on each of the dies (2). A marking pattern (220) may be formed on the opposite side (12) of the dies (2). The marking pattern (220) may be arranged on the inspection area (22). The marking pattern (220) may include information on each die (2). The marking pattern (220) may include, for example, a product code, specification information, and lot information for each die (2), but is not limited thereto.

[0050] Fig. 4 is a graph showing a first signal applied by a control unit to a first image sensor according to an exemplary embodiment. Fig. 5 is a diagram showing a first image according to an exemplary embodiment.

[0051] Referring to FIGS. 1 to 5, a first image sensor (4) according to an exemplary embodiment can move in a first direction (D1) and capture one side (11) of a wafer (10). The first image sensor (4) can capture one side (11) of the wafer (10) multiple times while moving in the first direction (D1). While the first image sensor (4) moves in the first direction (D1), the control unit (6) can apply a first signal (61) to the first image sensor (4) multiple times. The first image sensor (4) can receive the first signal (61) applied multiple times by the control unit (6) and capture one side (11) of the wafer (10) multiple times. The first image sensor (4) capturing one side (11) of the wafer (10) multiple times may capture each of the segmented areas (21) multiple times, but is not limited thereto.

[0052] According to an exemplary embodiment, a first image sensor (4) can acquire a first image (40) for a segmentation area (21) by photographing one side (11) of a wafer (10). The first image sensor (4) can acquire a plurality of first images (40) by photographing one side (11) of the wafer (10) a plurality of times. The first images (40) can include visual information for distinguishing each of the dies (2). Although the first image (40) illustrated in FIG. 5 includes visual information for one segmentation area (21), the technical idea according to the present disclosure is not limited thereto. For example, the first image (40) may also include visual information for a plurality of segmentation areas (21). The number of segmentation areas (21) for which visual information is provided by one first image (40) can be determined by, but is not limited to, a FOV (Field-of-view) of the first image sensor (4).

[0053] In the wafer inspection system (1) according to an exemplary embodiment, the time points at which the control unit (6) applies multiple first signals (61) to the first image sensor (4) may be the time points at which multiple first images (40) are acquired. The control unit (6) can control the time points at which the first images (40) are acquired by controlling the time points at which the first signals (61) are applied to the first image sensor (4).

[0054] Fig. 6 is a graph showing a second signal applied by a control unit to a second image sensor according to an exemplary embodiment. Fig. 7 is a diagram showing a second image according to an exemplary embodiment.

[0055] Referring to FIGS. 1 to 3, 6 and 7, a second image sensor (5) according to an exemplary embodiment can move in a first direction (D1) and capture an image of the opposite side (12) of the wafer (10). The second image sensor (5) can capture an image of the opposite side (12) of the wafer (10) multiple times while moving in the first direction (D1). While the second image sensor (5) moves in the first direction (D1), the control unit (6) can apply a second signal (62) to the second image sensor (5) multiple times. The second image sensor (5) can receive a plurality of second signals (62) applied by the control unit (6) and capture an image of the opposite side (12) of the wafer (10) multiple times. The second image sensor (5) may photograph the opposite side (12) of the wafer (10) multiple times, but is not limited thereto.

[0056] According to an exemplary embodiment, a second image sensor (5) can acquire a second image (50) for an inspection area (22) by photographing the opposite side (12) of the wafer (10). The second image sensor (5) can acquire a plurality of second images (50) by photographing the opposite side (12) of the wafer (10) a plurality of times. The second images (50) can include visual information for a marking pattern (220) formed on each of the dies (2). Although the second image (50) illustrated in FIG. 7 includes visual information for one inspection area (22), the technical idea according to the present disclosure is not limited thereto. For example, the second image (50) may also include visual information for a plurality of inspection areas (22). The number of inspection areas (22) for which visual information is provided by one second image (50) may be determined by, but is not limited to, the field-of-view (FOV) of the second image sensor (5).

[0057] In the wafer inspection system (1) according to an exemplary embodiment, the time points at which the control unit (6) applies multiple second signals (62) to the second image sensor (5) may be the time points at which multiple second images (50) are acquired. The control unit (6) can control the time points at which the second images (50) are acquired by controlling the time points at which the second signals (62) are applied to the second image sensor (5).

[0058] FIG. 8 is a drawing showing a third image according to an exemplary embodiment.

[0059] Referring to FIGS. 1 to 8, in a wafer inspection system (1) according to an exemplary embodiment, a control unit (6) may provide a third image (70) in which the first image (40) and the second image (50) are superimposed. The third image (70) may simultaneously provide visual information of the division area (21) and the inspection area (22) for each of the dies (2) included in the wafer (10). The third image (70) may provide visual information about the arrangement relationship between the division area (21) and the corresponding inspection area (22). At this time, when a marking pattern (220) is arranged in the inspection area (22), the quality of the marking pattern (220) for each of the dies (2) may be inspected through the third image (70), but the present disclosure is not limited thereto.

[0060] Meanwhile, since the wafer (10) includes a plurality of dies (2), a plurality of third images (70) may need to be provided in the process of inspecting one wafer (10). The time required for the process of inspecting the wafer (10) may be determined by the time required for providing the plurality of third images (70). If the plurality of third images (70) are provided within a short period of time, the time required for the process of inspecting the wafer (10) may be shortened. The time required for providing the plurality of third images (70) may be determined by the time required for acquiring the plurality of first images (40) and second images (50). If the plurality of first images (40) and second images (50) are provided within a short period of time, the time required for the process of inspecting the wafer (10) may be shortened.

[0061] In the process of each of the first image sensor (4) and the second image sensor (5) according to the exemplary embodiment taking multiple pictures of the wafer (10), the first image sensor (4) and the second image sensor (5) can move continuously in the first direction (D1). For example, in the process of the control unit (6) applying the first signal (61) to the first image sensor (4) multiple times, the movement of the first image sensor (4) moving in the first direction (D1) can be continuous. More specifically, at the time when the first image sensor (4) receiving the first signal (61) takes the first image (40), the first image sensor (4) can be in a state of moving in the first direction (D1). In other words, the first image sensor (4) can move in the first direction (D1) without stopping and acquire multiple first images (40). Likewise, the movement of the second image sensor (5) moving in the first direction (D1) in the process of the control unit (6) applying a plurality of second signals (62) to the second image sensor (5) may be continuous. More specifically, at the time when the second image sensor (5) receiving the second signal (62) captures the second image (50), the second image sensor (5) may be in a state of moving in the first direction (D1). In other words, the second image sensor (5) may move in the first direction (D1) without stopping and acquire a plurality of second images (50). However, the present invention is not limited thereto, and conversely, as described above, relative movement in the first direction (D1) of each of the first image sensor (4) and the second image sensor (5) with respect to the stage (3) may be provided by moving the stage (3).

[0062] In a wafer inspection system (1) according to an exemplary embodiment, when the first image sensor (4) and the second image sensor (5) continuously move in the first direction (D1) to capture a wafer (10), a plurality of first images (40) and second images (50) can be acquired in a short period of time. When a plurality of first images (40) and second images (50) are acquired in a short period of time, a plurality of third images (70) can be provided in a short period of time. When a plurality of third images (70) are provided in a short period of time, the time required for the process of inspecting the wafer (10) can be shortened. When the time required for the process of inspecting the wafer (10) is shortened, the number of wafers (10) that can be processed per hour (WPH; Wafer-per-hour) can be increased.

[0063] Meanwhile, when the second image sensor (5) of the first image sensor (4) continuously moves in the first direction (D1) to capture a wafer (10), a misalignment between the first image (40) and the second image (50) may occur due to a physical error. For example, when the starting positions or starting times of the first image sensor (4) and the second image sensor (5) are different, a misalignment between the first image (40) and the second image (50) may occur. Here, the misalignment between the first image (40) and the second image (50) may mean that the center (400) of the first image (40) and the center (500) of the second image (50) do not match. When the first image (40) and the second image (50) are misaligned, the arrangement of the inspection area (22) displayed for each die (2) on the third image (70) may be misaligned. If the arrangement of the inspection areas (22) displayed for each die (2) on the third image (70) is misaligned, the inspection quality of the wafer inspection system (1) may deteriorate.

[0064] The control unit (6) according to an exemplary embodiment can control the signals applied to each of the first image sensor (4) and the second image sensor (5) so that the centers of the first image (40) and the second image (50) coincide within the third image (70). Hereinafter, the function of the control unit (6) that controls the timing of photographing the wafer (10) by controlling the first signal (61) and the second signal (62) applied to each of the first image sensor (4) and the second image sensor (5) will be described in more detail.

[0065] Fig. 9 is a diagram showing a third image according to an exemplary embodiment. Fig. 10 is a graph showing a first signal and a second signal applied by a control unit to each of a first image sensor and a second image sensor according to an exemplary embodiment. In Fig. 9, a first image (40) captured by a first image sensor (4) is spaced apart in a first direction (D1) with respect to a second image (50) captured by a second image sensor (5), and a third image (70a) in which an inspection area (22) is misaligned in a die (2) is expressed. In Fig. 10, an offset (600) applied by the control unit (6) to the first signal (61) to correct the third image (70a) in which an inspection area (22) is misaligned in a die (2) in Fig. 9 is expressed. At this time, although the drawings in FIGS. 9 and 10 are expressed based on an embodiment in which the first image sensor (4) and the second image sensor (5) photograph the wafer (10) in the first direction (D1), the present invention is not limited thereto. For example, when the first image sensor (4) and the second image sensor (5) move in a direction opposite to the first direction (D1) and photograph the wafer (10), the positions of the configurations expressed in FIGS. 9 and 10 can be arranged to be reversed left and right, and it can be easily understood by those skilled in the art that the contents described below can also be applied in the opposite direction.

[0066] Referring to FIGS. 1 to 10, in an exemplary embodiment, a control unit (6) may apply a positive offset (600) to a first signal (61) applied to the first image sensor (4) when the center (400) of the first image (40) is spaced apart in the first direction (D1) with respect to the center (500) of the second image (50) within the third image (70), thereby matching the center (400) of the first image (40) and the center (500) of the second image (50). When the control unit (6) applies a positive offset (600) to the first signal (61) applied to the first image sensor (4), the point in time at which the first image sensor (4) acquires the first image (40) may be delayed. When the time at which the first image sensor (4) that moves in the first direction (D1) and takes multiple pictures of one side (11) of the wafer (10) acquires the first image (40) is delayed, the position at which the first image (40) is acquired may move in parallel in a direction opposite to the first direction (D1) on the one side (11) of the wafer (10). In other words, the center (400) of the first image (40) may move in parallel in a direction opposite to the first direction (D1). When the center (400) of the first image (40) in the third image (70a) is spaced apart in the first direction (D1) with respect to the center (500) of the second image (50), the control unit (6) applies a positive offset (600) to the first signal (61) applied to the first image sensor (4) to move the center (400) of the first image (40) in a direction opposite to the first direction (D1), thereby making the centers of the first image (40) and the second image (50) coincide. However, the present invention is not limited thereto, and the control unit (6) may align the centers of the first image (40) and the second image (50) by applying a negative (-) offset to the second signal (62) applied to the second image sensor (5) when the center of the first image (40) in the third image (70) is spaced apart in the first direction (D1) with respect to the center of the second image (50).

[0067] Fig. 11 is a diagram showing a third image according to an exemplary embodiment. Fig. 12 is a graph showing a first signal and a second signal applied by a control unit to each of a first image sensor and a second image sensor according to an exemplary embodiment. In Fig. 11, a third image (70b) in which a second image (50) captured by a second image sensor (5) is spaced apart in a first direction (D1) with respect to a first image (40) captured by a first image sensor (4), and an inspection area (22) is misaligned in a die (2) is expressed. In Fig. 12, an offset (600) applied by the control unit (6) to the second signal (62) to correct the third image (70) in which the inspection area (22) is misaligned in a die (2) in Fig. 11 is expressed. At this time, although the drawings in FIGS. 11 and 12 are expressed based on an embodiment in which the first image sensor (4) and the second image sensor (5) photograph the wafer (10) in the first direction (D1), the present invention is not limited thereto. For example, when the first image sensor (4) and the second image sensor (5) move in a direction opposite to the first direction (D1) and photograph the wafer (10), the positions of the configurations expressed in FIGS. 11 and 12 can be arranged to be reversed left and right, and it can be easily understood by those skilled in the art that the contents described below can also be applied in the opposite direction.

[0068] Referring to FIGS. 1 to 8, 11 and 12, in an exemplary embodiment, the control unit (6) may apply a positive offset (600) to the second signal (62) applied to the second image sensor (5) when the center (500) of the second image (50) within the third image (70b) is spaced apart in the first direction (D1) with respect to the center (400) of the first image (40), thereby matching the center (400) of the first image (40) and the center (500) of the second image (50). When the control unit (6) applies a positive offset (600) to the second signal (62) applied to the second image sensor (5), the point in time at which the second image sensor (5) acquires the second image (50) may be delayed. When the time at which the second image sensor (5) that moves in the first direction (D1) and takes multiple pictures of one side (11) of the wafer (10) acquires the second image (50) is delayed, the position at which the second image (50) is acquired may move parallel to the direction opposite to the first direction (D1) on the one side (11) of the wafer (10). In other words, the center of the second image (50) may move parallel to the direction opposite to the first direction (D1). The control unit (6) applies a positive offset (600) to the second signal (62) applied to the second image sensor (5) when the center (500) of the second image (50) in the third image (70) is spaced apart in the first direction (D1) with respect to the center (400) of the first image (40), thereby moving the center (500) of the second image (50) in a direction opposite to the first direction (D1), thereby making the centers of the first image (40) and the second image (50) coincide. However, the present invention is not limited thereto, and the control unit (6) may align the centers of the first image (40) and the second image (50) by applying a negative offset (600) to the first signal (61) applied to the first image sensor (4) when the center of the second image (50) in the third image (70b) is spaced apart in the first direction (D1) with respect to the center of the first image (40).

[0069] Fig. 13 is a plan view of a wafer inspection system according to an exemplary embodiment. Fig. 14 is a plan view of a wafer inspection system according to an exemplary embodiment. Fig. 15 is a plan view of a wafer inspection system according to an exemplary embodiment.

[0070] Referring to FIGS. 1 to 15, in a wafer inspection system (1) according to an exemplary embodiment, a wafer (10) may include a plurality of inspection rows (R) for a plurality of dies (2), each of which is arranged in a first direction (D1). Each of the plurality of inspection rows (R) may be defined by, but is not limited to, a movement path of a first image sensor (4) and a second image sensor (5) on a stage (3). The plurality of inspection rows (R) may be arranged at a predetermined interval from each other in a second direction (D2) intersecting the first direction (D1). In other words, the plurality of inspection rows (R) may be arranged in a row in the second direction (D2) intersecting the first direction (D1).

[0071] In a wafer inspection system (1) according to an exemplary embodiment, when inspection for one of a plurality of inspection rows (R) is completed by each of the first image sensor (4) and the second image sensor (5) moving in a first direction (D1) and taking multiple pictures of the wafer (10), each of the first image sensor (4) and the second image sensor (5) can move to an adjacent inspection row (R) by moving in a second direction (D2). Each of the first image sensor (4) and the second image sensor (5) can take pictures of a plurality of inspection rows (R) by sequentially moving in the first direction (D1) and a third direction (D3) opposite to the first direction (D1). However, this is not limited thereto, and conversely, as the stage (3) moves, relative movement in the first direction (D1) and the third direction (D3) opposite to the first direction (D1) with respect to the stage (3) can be sequentially provided to each of the first image sensor (4) and the second image sensor (5), as described above.

[0072] Below, a method for inspecting a subject according to an exemplary embodiment will be described. Any overlap with the above will be omitted, and the explanation will focus on the differences.

[0073] Fig. 16 is a drawing showing a method for inspecting a target according to an exemplary embodiment.

[0074] Referring to FIGS. 1 to 16, a method for inspecting an object according to an exemplary embodiment may include a step (S101) of loading an object onto a stage (3). Here, the object may be, but is not limited to, a wafer (10) including a plurality of dies (2).

[0075] A method for inspecting an object according to an exemplary embodiment may include a step (S102) of acquiring a reference image for the object. The step (S102) of acquiring a reference image for the object may be a step (S102) of acquiring a reference image for the object by allowing each of a first image sensor (4) and a second image sensor (5), which are arranged to face each other with respect to a stage (3) as the center, to move in a first direction (D1) relative to the stage (3) and photographing the object multiple times. The relative movement provided to each of the first image sensor (4) and the second image sensor (5) with respect to the stage (3) may be formed by each of the first image sensor (4) and the second image sensor (5) moving in the first direction (D1), but is not limited thereto. The first image sensor (4) and the second image sensor (5) may be arranged to face each other with respect to the object. The first image sensor (4) may be arranged on top of the object and may photograph one side (11) of the object. The first reference image acquired by the first image sensor (4) may be, for example, a first image (40) for a division area (21) of a plurality of dies (2), but is not limited thereto. The second image sensor (5) is disposed below the object and can capture the opposite side (12) of the object. The second reference image acquired by the second image sensor (5) may be, for example, a second image (50) for an inspection area (22) of a plurality of dies (2), but is not limited thereto. In addition, a marking pattern (220) is disposed in the inspection area (22) of the dies (2), and the second reference image may provide information on the marking quality of each of the dies (2), but is not limited thereto.

[0076] A method for inspecting an object according to an exemplary embodiment may include a step (S103) of superimposing a first reference image and a second reference image to determine whether they are synchronized. Here, determining whether they are synchronized may involve determining whether the first reference image and the second reference image are misaligned. In this case, the step (S103) of determining whether they are synchronized may involve determining whether the centers of the first reference image and the second reference image are aligned, thereby determining whether they are synchronized.

[0077] A method for inspecting an object according to an exemplary embodiment may include a step (S104) of synchronizing a first reference image and a second reference image. The step (S104) of synchronizing the first reference image and the second reference image may perform synchronization by controlling a photographing time of the first image sensor (4) or the second image sensor (5). Controlling the photographing time of the first image sensor (4) or the second image sensor (5) may be performed by applying an offset (600) to a first signal (61) or a second signal (62) applied by a control unit (6), but is not limited thereto.

[0078] In the step (S104) of synchronizing the first reference image and the second reference image according to an exemplary embodiment, when the center of the first reference image is spaced apart in the first direction (D1) with respect to the center of the second reference image, the centers of the first reference image and the second reference image can be aligned by delaying the shooting time of the first image sensor (4). Delaying the shooting time of the first image sensor (4) may be, but is not limited to, applying a positive offset (600) to the first signal (61) applied by the control unit (6) to the first image sensor (4).

[0079] In the step (S104) of synchronizing the first reference image and the second reference image according to an exemplary embodiment, if the center of the second reference image is spaced apart in the first direction (D1) with respect to the center of the first reference image, the centers of the first reference image and the second reference image can be aligned by delaying the shooting time of the second image sensor (5). Delaying the shooting time of the second image sensor (5) may be, but is not limited to, applying a positive offset (600) to the second signal (62) applied by the control unit (6) to the second image sensor (5).

[0080] In the step (S102) of acquiring a reference image for a target object according to an exemplary embodiment, the relative movement with respect to the stage (3) provided to each of the first image sensor (4) and the second image sensor (5) may be performed continuously. When the relative movement with respect to the stage (3) provided to each of the first image sensor (4) and the second image sensor (5) is performed continuously, the speed of inspecting the target object may be fast. When the relative movement with respect to the stage (3) provided to each of the first image sensor (4) and the second image sensor (5) is performed continuously, the number of targets that can be inspected per hour may be large.

[0081] The above-described embodiments are merely illustrative, and those skilled in the art will readily appreciate various modifications and equivalent alternative embodiments. Therefore, the true scope of technical protection afforded by the exemplary embodiments should be determined by the technical concepts set forth in the following claims.

Claims

1. In a wafer inspection system configured to inspect a wafer loaded on a stage, A first image sensor that photographs one side of the wafer multiple times; A second image sensor that photographs the opposite side of the wafer multiple times; and A control unit that controls the timing of photographing the wafer by applying a photographing signal to each of the first image sensor and the second image sensor; Each of the first image sensor and the second image sensor moves relative to the stage in a first direction, A wafer inspection system in which the relative movement is continuously performed during the process in which each of the first image sensor and the second image sensor captures the wafer multiple times.

2. In paragraph 1, The above wafer includes a plurality of dies arranged in the first direction, The first image sensor acquires a first image for a distinguishing area that distinguishes each of the dies, A wafer inspection system, wherein the second image sensor acquires a second image for an inspection area corresponding to the division area.

3. In paragraph 2, A marking pattern is placed in the above inspection area, The above control unit, A wafer inspection system that provides a third image in which the first image and the second image are superimposed so as to inspect the quality of the marking pattern for each of the dies.

4. In paragraph 3, The above control unit, A wafer inspection system that controls signals applied to each of the first image sensor and the second image sensor so that the centers of the first image and the second image coincide within the third image.

5. In paragraph 4, The above control unit, If the center of the first image within the third image is spaced in the first direction relative to the center of the second image, Applying a positive offset to the first signal applied to the first image sensor so as to delay the time point at which the first image is acquired, or By applying a negative offset to the second signal applied to the second image sensor so as to advance the time point at which the second image is acquired, A wafer inspection system that aligns the centers of the first image and the second image.

6. In paragraph 4, The above control unit, If the center of the second image within the third image is spaced apart in the first direction based on the center of the first image, Applying a positive offset to the second signal applied to the second image sensor so as to delay the time point at which the second image is acquired, or By applying a negative offset to the first signal applied to the first image sensor so as to advance the time point at which the first image is acquired, A wafer inspection system that aligns the centers of the first image and the second image.

7. In paragraph 1, The wafer includes a plurality of inspection rows for the plurality of dies, each of which is arranged in the first direction, The above plurality of inspection columns are arranged in a row in a second direction intersecting the first direction, Between each of the first image sensor and the second image sensor and the stage, A wafer inspection system that photographs the plurality of inspection rows by sequentially providing relative movements in the first direction and a third direction opposite to the first direction.

8. In paragraph 1, The first image and the second image acquired by the first image sensor and the second image sensor are, A wafer inspection system, which is image information for individual dies constituting the above plurality of dies.

9. Step of loading the object onto the stage; A step of obtaining a reference image of the object by allowing each of the first image sensor and the second image sensor, which are arranged to face each other with respect to the stage, to move in a first direction relative to the stage and photograph the object multiple times; A step of determining whether synchronization is achieved by superimposing a first reference image acquired by the first image sensor and a second reference image acquired by the second image sensor; and A step of synchronizing the first reference image and the second reference image by controlling the shooting point of the first image sensor or the second image sensor; including; In the step of acquiring a reference image for the above object, A method for inspecting an object, wherein the relative movement of each of the first image sensor and the second image sensor with respect to the stage is performed continuously.

10. In paragraph 9, In the step of determining whether the above synchronization is performed, A method for inspecting an object, wherein the center of the first reference image and the second reference image are determined to be coincident.

11. In paragraph 10, In the step of synchronizing the first reference image and the second reference image, If the center of the first reference image is spaced in the first direction relative to the center of the second reference image, A method for inspecting an object, wherein the centers of the first reference image and the second reference image are aligned by delaying the shooting time of the first image sensor.

12. In paragraph 10, In the step of synchronizing the first reference image and the second reference image, If the center of the second reference image is spaced in the first direction relative to the center of the first reference image, A method for inspecting an object, wherein the centers of the first reference image and the second reference image are aligned by delaying the shooting time of the second image sensor.

13. In paragraph 9, The above object is a wafer including a plurality of dies, The above first reference image provides information about the distinguishing area that can distinguish each of the dies, A method for inspecting an object, wherein the second reference image provides information about an inspection area corresponding to the division area.

14. In paragraph 13, A marking pattern is placed in the above inspection area, A method for inspecting an object, wherein the second reference image provides information on the marking quality of each of the dies.

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