System and method for detecting front and back surfaces of wafer

Abstract

The invention discloses a wafer front and back surface detection system and method, and the system comprises a first scanning system which comprises a first light source module and a first camera module, and a second scanning system which comprises a second light source module and a second camera module. Light spot positions formed on the front surface and the back surface of the wafer by the first light source module and the second light source module are mutually staggered along projection positions on the front surface or the back surface of the wafer, or the projection directions of illumination light emitted by the first light source module and illumination light emitted by the second light source module are different; the first camera module and the second camera module respectively collect front or back images of the wafer to obtain a scanning result, and the analysis module analyzes the scanning result to obtain a detection result. The illumination light spots on the front and back surfaces of the wafer are staggered or the projection directions of the illumination light are different, so that the problem of mutual interference of light beams generated in the synchronous detection process of the front and back surfaces of the wafer is avoided, and the accuracy of the detection result of the front and back surfaces of the wafer is improved.

Description

Technical Field

[0001] This application relates to the technical field of wafer detection, and particularly to a front and back surface detection system and method for wafers. Background Art

[0002] The manufacturing of semiconductor components often requires a series of extremely precise and complex production processes. During the manufacturing of semiconductor components, wafers are often damaged due to defects on the wafer surface caused by contamination and poor processes such as dust, dirt, scratches, and foreign particles. Therefore, it is necessary to detect and monitor such defects to improve the yield of wafer production. Under specific wafer manufacturing processes, defects on both the front and back surfaces of the wafer need to be detected, so front and back surface imaging of the wafer is particularly important. Currently, a flipping mechanism is usually set in a wafer detection device. After the front surface of the wafer is detected, the wafer is flipped to the back surface by the flipping mechanism, and then the back surface of the wafer is detected. However, this detection device will reduce the efficiency of front and back surface detection of the wafer.

[0003] In order to improve the efficiency of wafer detection, some existing wafer detection devices are respectively provided with independent illumination microscopy imaging systems on the front and back sides of the wafer to detect the front and back surfaces of the wafer simultaneously. However, although this method can improve the efficiency of wafer detection, it uses multiple light sources to simultaneously scan and image the front and back surfaces of the wafer. During this process, the front and back surface light sources emit light simultaneously, which is very likely to cause light beam counterpropagation. When there are situations such as wafer thinning and etching gaps, there is a possibility of light transmission, and there is also a possibility of light leakage at the edge of the wafer, resulting in stray light interfering with the original light spot. Even worse, the stray light will reflect on the light emitting surface of the light source, further causing multiple imaging, resulting in serious interference and affecting the overall detection performance of the system, reducing the accuracy of wafer detection. Summary of the Invention

[0004] In view of this, this application provides a front and back surface detection system and method for wafers to solve the problem of light beam interference existing in the existing front and back surface detection of wafers.

[0005] To solve the above technical problems, a technical solution adopted in this application is: to provide a front and back detection system for wafers, which includes: a carrying and driving stage for loading wafers and performing linear movement; a first scanning system disposed on one side of the wafer, the first scanning system includes a first light source module and a first camera module, the first light source module emits illumination light to a first position to be measured on the front of the wafer, and the first camera module is used to collect an image of the front of the wafer to obtain a first scanning result; a second scanning system disposed on the other side of the wafer, the second scanning system includes a second light source module and a second camera module, the second light source module emits illumination light to a second position to be measured on the back of the wafer, and the second camera module is used to collect an image of the back of the wafer to obtain a second scanning result; an analysis module electrically connected to the first scanning system and the second scanning system respectively, for analyzing the first scanning result and the second scanning result to obtain a detection result of the wafer; wherein, the projection positions of the first position to be measured and the second position to be measured on the front or back of the wafer are staggered from each other, or, the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module are different.

[0006] As a further improvement of this application, the first light source module includes a first bright field illumination unit, and the first illumination light emitted by the first bright field illumination unit is irradiated to the first position to be measured in a first projection direction; the second light source module includes a second bright field illumination unit, and the third illumination light emitted by the second bright field illumination unit is irradiated to the second position to be measured in a third projection direction; the angles of the first projection direction and the third projection direction relative to the plane of the wafer are the same, the first projection direction and the third projection direction are parallel in space, and the projection positions of the first position to be measured and the second position to be measured on the front or back of the wafer are staggered from each other by a first preset distance.

[0007] The first light source module further includes a first dark field illumination unit, and the second illumination light emitted by the first dark field illumination unit is irradiated to the first position to be measured in a second projection direction; the second light source module further includes a second dark field illumination unit, and the fourth illumination light emitted by the second dark field illumination unit is irradiated to the second position to be measured in a fourth projection direction; the angles of the second projection direction and the fourth projection direction relative to the plane of the wafer are the same, the second projection direction and the fourth projection direction are parallel in space, and the projection positions of the first position to be measured and the second position to be measured on the front or back of the wafer are staggered from each other by a second preset distance.

[0008] As a further improvement of the present application, the first light source module includes a first bright field illumination unit, and the first illumination light emitted by the first bright field illumination unit is irradiated to the first position to be measured in a first projection direction; the second light source module includes a second bright field illumination unit, and the third illumination light emitted by the second bright field illumination unit is irradiated to the second position to be measured in a third projection direction; the first projection direction and the third projection direction are different, and by configuring the spatial intersection position, the projection positions of the first position to be measured and the second position to be measured on the front side or the back side of the wafer overlap or are staggered.

[0009] The first light source module also includes a first dark field illumination unit, and the second illumination light emitted by the first dark field illumination unit is illuminated to the first position to be measured in a second projection direction; the second light source module also includes a second dark field illumination unit, and the fourth illumination light emitted by the second dark field illumination unit is illuminated to the second position to be measured in a fourth projection direction; the second projection direction is different from the fourth projection direction, and the spatial intersection position is configured so that the projection positions of the first position to be measured and the second position to be measured on the front side or the back side of the wafer overlap or are staggered.

[0010] As a further improvement of the present application, when the first bright field illumination unit is turned on, the second bright field illumination unit is turned on synchronously; or, when the first dark field illumination unit is turned on, the second dark field illumination unit is turned on synchronously; the first illumination light, the second illumination light, the third illumination light, and the fourth illumination light are all linear light beams, and the length direction of the linear light beam is perpendicular to the movement direction of the wafer.

[0011] As a further improvement of the present application, the first bright field illumination unit and the second bright field illumination unit both have corresponding adjustment devices for adjusting at least one of the pitch angle, the horizontal position, and the vertical position so that the first projection direction of the first illumination light and the third projection direction of the third illumination light are within a first preset angle range; and / or the first dark field illumination unit and the second dark field illumination unit have corresponding adjustment devices for adjusting at least one of the pitch angle, the horizontal position, and the vertical position so that the second projection direction of the second illumination light and the fourth projection direction of the fourth illumination light are within a second preset angle range.

[0012] As a further improvement of the present application, the first camera module includes a first imaging lens, a first line array camera, and a first camera adjustment device. The first imaging lens is configured to receive the reflected light of the first illumination light on the surface of the wafer or the scattered light of the second illumination light on the surface of the wafer, and transmit the received light beam to the first line array camera. The first camera adjustment device is configured to adjust at least one of the pitch angle, horizontal position, and vertical position of the first imaging lens, so that the optical axis of the first imaging lens is symmetric with respect to the normal line of the wafer surface to the optical axis of the first bright field illumination unit; and / or, the second camera module includes a second imaging lens, a second line array camera, and a second camera adjustment device. The second imaging lens is configured to receive the reflected light of the third illumination light on the surface of the wafer or the scattered light of the fourth illumination light on the surface of the wafer, and transmit the received light beam to the second line array camera. The second camera adjustment device is configured to adjust at least one of the pitch angle, horizontal position, and vertical position of the second imaging lens, so that the optical axis of the second imaging lens is symmetric with respect to the normal line of the wafer surface to the optical axis of the second bright field illumination unit.

[0013] As a further improvement of the present application, the first light source module further includes a third dark field illumination unit. The third dark field illumination unit is symmetrically arranged with respect to the normal line of the wafer surface to the first dark field illumination unit. The third dark field illumination unit is configured to emit a fifth illumination light, and the spot areas of the fifth illumination light and the second illumination light on the wafer surface overlap; and / or, the second light source module further includes a fourth dark field illumination unit. The fourth dark field illumination unit is symmetrically arranged with respect to the normal line of the wafer surface to the second dark field illumination unit. The fourth dark field illumination unit is configured to emit a sixth illumination light, and the spot areas of the sixth illumination light and the fourth illumination light on the wafer surface overlap.

[0014] As a further improvement of the present application, the carrier driving stage includes a carrying part and a driving part. The carrying part is arranged on the driving part. The carrying part is configured to carry and define the wafer, and the driving part is configured to drive the carrying part to move to drive the wafer to perform a linear movement.

[0015] To solve the above technical problems, another technical solution adopted by the present application is: to provide a method for detecting the front and back sides of a wafer, which is applied to the wafer front and back side detection system as described above; the method includes: loading the wafer to be detected onto the carrier driving stage; the first light source module is turned on and emits illumination light to the first position to be measured on the front side of the wafer, and the second light source module is turned on and emits illumination light to the second position to be measured on the back side of the wafer; the first position to be measured and the second position to be measured are staggered from each other along the projection positions on the front or back side of the wafer, or the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module are different; the carrier driving stage drives the wafer to perform a linear movement; the first camera module collects an image of the front side of the wafer to obtain a first scanning result, and the second camera module collects an image of the back side of the wafer to obtain a second scanning result; the analysis module analyzes the first scanning result and the second scanning result to obtain the detection result of the wafer.

[0016] The beneficial effects of the present application are as follows:

[0017] In the front and back surface detection system of the wafer of the present application, a first scanning system and a second scanning system are respectively arranged on both sides of a carrier driving stage for loading the wafer. The first light source module of the first scanning system emits first illumination light to a first position to be measured on the front surface of the wafer, and the first camera module of the first scanning system scans the front surface of the wafer to obtain a first scanning result. At the same time, the second light source module of the second scanning system emits second illumination light to a second position to be measured on the back surface of the wafer, and the second camera module of the second scanning system scans the back surface of the wafer to obtain a second scanning result. The first position to be measured and the second position to be measured are staggered from each other, or the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module are different. Even if there are situations such as thinning and partial etching on the wafer surface, the illumination light beams on the front and back surfaces of the wafer will not be in opposite directions, and there will be no problem of mutual interference of the illumination spots, which is beneficial to improving the accuracy of the scanning result and ultimately improving the accuracy of the wafer detection result. Description of the Drawings

[0018] Figure 1 is a schematic structural diagram of an embodiment of the front and back surface detection system of the wafer of the present invention;

[0019] Figure 2 is a schematic diagram of the electrical connection relationship of an embodiment of the front and back surface detection system of the wafer of the present invention;

[0020] Figure 3 is a schematic structural diagram of another embodiment of the front and back surface detection system of the wafer of the present invention;

[0021] Figure 4 is a schematic structural diagram of yet another embodiment of the front and back surface detection system of the wafer of the present invention;

[0022] Figure 5 is a schematic diagram of the electrical connection relationship of another embodiment of the front and back surface detection system of the wafer of the present invention;

[0023] Figure 6 is a schematic flowchart of an embodiment of the front and back surface detection method of the wafer of the present invention. Detailed Embodiments

[0024] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present application.

[0025] The terms "first", "second", and "third" in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", and "third" may explicitly or implicitly include at least one of such features. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined. All directional indications (such as up, down, left, right, front, back...) in the embodiments of this application are only used to explain the relative spatial positions, movement conditions, etc. of the components in a specific posture (as shown in the drawings). If the specific posture changes, then the directional indications will also change accordingly. In addition, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0026] Reference to "embodiment" in this context means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0027] Figure 1 is a schematic structural diagram of the front and back surface detection system of the wafer in the embodiment of the present invention. As Figure 1 shown, the front and back surface detection system of the wafer includes: a loading and driving stage 1, a first scanning system 2, a second scanning system 3, and an analysis module 4 (please refer to Figure 2 together).

[0028] The loading and driving stage 1 is used to load the wafer and perform linear movement.

[0029] The first scanning system 2 is arranged on one side of the wafer. The first scanning system 2 includes a first light source module 21 and a first camera module 22. The first light source module 21 emits first illumination light to the first position to be measured on the front surface of the wafer, and the first camera module 22 is used to collect an image of the front surface of the wafer to obtain a first scanning result.

[0030] The second scanning system 3 is arranged on the other side of the wafer. The second scanning system 3 includes a second light source module 31 and a second camera module 32. The second light source module 31 emits second illumination light to the second position to be measured on the back surface of the wafer, and the second camera module 32 is used to collect an image of the back surface of the wafer to obtain a second scanning result.

[0031] The analysis module 4 is electrically connected to the first scanning system 2 and the second scanning system 3 respectively, and is used for analyzing the first scanning result and the second scanning result to obtain the detection result of the wafer.

[0032] Among them, the projected positions of the first position to be measured and the second position to be measured on the front or back surface of the wafer are offset from each other, or the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module are different. It can be understood that in the case where the projected positions are offset from each other, regardless of whether the projection directions are the same, special situations such as light transmission and light leakage of the illumination light on both sides of the wafer will not cause the light beams to shoot at each other, and will not affect the imaging effect of the illumination spot; similarly, in the case where the projection directions are different, regardless of whether the projected positions are offset, special situations such as light transmission and light leakage occurring on the wafer will not cause the light beams to shoot at each other, and the imaging effect of the illumination spot is also not affected.

[0033] In this embodiment, the relative spatial position relationship among the carrier driving stage 1, the first scanning system 2, and the second scanning system 3 is preset, so that the first light source module 21 emits the first illumination light to the first position to be measured on the front surface of the wafer and the second light source module 31 emits the second illumination light to the second position to be measured on the back surface of the wafer. The projected positions of the first position to be measured and the second position to be measured on the front or back surface of the wafer are offset from each other, or the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module are different. Thus, even when there are situations such as wafer thinning, etching gaps, and edge light leakage on the wafer, the illumination light shooting from one side of the wafer to the other side will not interfere with the illumination spot and will not affect the imaging effect.

[0034] It should be noted that for the case where the projected positions of the first position to be measured and the second position to be measured on the front or back surface of the wafer are offset from each other, it can be achieved by adjusting the tilt angles of the first light source module 21 and the second light source module 31, so that the light source projection directions of the first light source module 21 and the second light source module 31 are different, thereby offsetting the positions of the illumination spots; it can also be achieved by making the light source projection directions of the first light source module 21 and the second light source module 31 the same but the optical axes not coincident, so that the focusing positions of the first light source module 21 and the second light source module 31 on the front and back surfaces of the wafer are different, thereby offsetting the positions of the illumination spots; it can also be achieved by the results of the above two methods at the same time to offset the positions of the illumination spots.

[0035] It should be noted that, in the case where the projection directions of the illumination light emitted by the first light source module 21 and the illumination light emitted by the second light source module 31 are different, the inclination angles of the first light source module 21 and the second light source module 31 can be adjusted so that the projection directions of the light sources of the first light source module 21 and the second light source module 31 are different. The projection directions can intersect in space, and when the intersection position is on the wafer, the projection positions of the first position to be measured and the second position to be measured on the front side or the back side of the wafer will overlap; when the intersection position is not on the wafer, the projection positions of the first position to be measured and the second position to be measured on the front side or the back side of the wafer will be staggered from each other.

[0036] Among them, it needs to be understood that the first position to be measured refers to a fixed position on the first plane where the front side of the wafer is located, that is, the optical detection position on the front side of the wafer, and the second position to be measured refers to a fixed position on the second plane where the back side of the wafer is located, that is, the optical detection position on the back side of the wafer. The wafer will perform linear motion during the scanning process, but the first position to be measured and the second position to be measured will not move with the movement of the wafer.

[0037] Specifically, when performing front and back side inspection of the wafer, the wafer is loaded onto the carrying drive platform 1, and then the first light source module 21 and the second light source module 31 are turned on, so that the illumination light emitted by the first light source module 21 is irradiated to the first position to be tested on the front side of the wafer, and the illumination light emitted by the second light source module 31 is irradiated to the second position to be tested on the back side of the wafer, and then the first camera module 22 and the second camera module 32 are turned on, and then the wafer is driven to perform linear motion, and the first camera module 22 is used to collect the first scanning result of the front side of the wafer and the second camera module 32 is used to collect the second scanning result of the back side of the wafer, and finally the first scanning result and the second scanning result are sent to the analysis module 4 for analysis to obtain the inspection results of the front and back sides of the wafer.

[0038] The front and back surface detection system of this embodiment measures the first scanning system 2 and the second scanning system 3 respectively on the carrier driving stage 1 for loading the wafer. The first light source module 21 of the first scanning system 2 emits illumination light to the first position to be measured on the front surface of the wafer, and the first camera module 22 of the first scanning system 2 scans the front surface of the wafer to obtain a first scanning result. At the same time, the second light source module 31 of the second scanning system 3 emits illumination light to the second position to be measured on the back surface of the wafer, and the second camera module 32 of the second scanning system 3 scans the back surface of the wafer to obtain a second scanning result. The first position to be measured and the second position to be measured are staggered from each other, that is, the illumination spots of the first scanning system 2 and the second scanning system 3 on the front and back surfaces of the wafer are staggered from each other, or the projection directions of the illumination light emitted by the first light source module 21 and the illumination light emitted by the second light source module 31 are different. Therefore, even if there are situations such as thinning and partial etching on the wafer surface, the illumination spots on the front and back surfaces of the wafer will not interfere with each other, thereby improving the accuracy of the scanning result and ultimately improving the accuracy of the wafer detection result.

[0039] In a specific embodiment, in order to improve the detection performance of the front and back surface detection system of the wafer, a system optical structure is constructed as Figure 1 shown. The first light source module 21 includes a first bright field illumination unit 211, and the first illumination light emitted by the first bright field illumination unit 211 irradiates the first position to be measured in the first projection direction; the second light source module 31 includes a second bright field illumination unit 311, and the third illumination light emitted by the second bright field illumination unit 311 irradiates the second position to be measured in the third projection direction. The angle sizes of the first projection direction and the third projection direction relative to the plane where the wafer is located are the same, the first projection direction and the third projection direction are parallel in space, and the first position to be measured and the second position to be measured are staggered from each other in the projection positions on the front or back surface of the wafer by a first preset distance.

[0040] Furthermore, referring to Figure 1 , the first light source module 21 further includes a first dark field illumination unit 212, and the second illumination light emitted by the first dark field illumination unit 212 irradiates the first position to be measured in the second projection direction; the second light source module 31 further includes a second dark field illumination unit 312, and the fourth illumination light emitted by the second dark field illumination unit 312 irradiates the second position to be measured in the fourth projection direction. The angle sizes of the second projection direction and the fourth projection direction relative to the plane where the wafer is located are the same, the second projection direction and the fourth projection direction are parallel in space, and the first position to be measured and the second position to be measured are staggered from each other in the projection positions on the front or back surface of the wafer by a second preset distance.

[0041] It should be noted that the first projection direction, the second projection direction, the third projection direction, and the fourth projection direction mentioned here are all the spatial directions in which the illumination beam is incident on the wafer surface, and there will be a certain angle between them and the plane where the wafer is located or the wafer normal.

[0042] See Figure 1 , the first bright-field illumination unit 211 is inclined relative to the front side of the wafer, so that there is a certain angle between the optical path of the first illumination light emitted by the first bright-field illumination unit 211 and the front side of the wafer, and this angle is not 90°, that is, the first illumination light emitted by the first bright-field illumination unit 211 is obliquely irradiated on the first position to be measured on the front side of the wafer in the first projection direction, and the angle corresponding to the first projection direction is not equal to 0°; moreover, the second illumination light emitted by the first dark-field illumination unit 212 is obliquely irradiated on the first position to be measured on the front side of the wafer in the second projection direction, and the angle corresponding to the second projection direction is not equal to 0°. It should be noted that the first projection direction and the second projection direction are not equal, so that the bright-field illumination beam and the dark-field illumination light have different oblique irradiation angles respectively. Similarly, the third illumination light emitted by the second bright-field illumination unit 311 is obliquely irradiated on the second position to be measured on the back side of the wafer in the third projection direction; moreover, the fourth illumination light emitted by the second dark-field illumination unit 312 is obliquely irradiated on the second position to be measured on the back side of the wafer in the fourth projection direction, and the third projection direction and the fourth projection direction are not equal, so that the bright-field illumination beam and the dark-field illumination light have different oblique irradiation angles respectively.

[0043] It can be understood that by setting the bright-field illumination and imaging methods with oblique irradiation on both the front and back sides of the wafer, and setting the dark-field illumination and imaging methods with oblique irradiation, the illumination angle and the imaging angle can be adjusted for different defect types, thereby strengthening the compatibility of bright-field and dark-field detection on the front and back sides of the wafer, and further improving the overall detection performance of the system.

[0044] In some cases, the angles corresponding to the first projection direction and the third projection direction are the same, the first projection direction and the third projection direction are parallel in space and separated by a first preset distance; the angles corresponding to the second projection direction and the fourth projection direction are the same, the second projection direction and the third projection direction are parallel in space and separated by a second preset distance; different irradiation positions are achieved by the way that the beam directions are opposite and spaced in space. The first preset distance and the second preset distance here can be set according to the characteristics of the illumination beam and the specified detection accuracy of the system, for example, set between dozens of micrometers and hundreds of micrometers. It can be understood that since different types of defects have different sensitivities to light with different irradiation angles, the bright-field or dark-field detection of the characteristics of the same type of defects on the front and back sides of the wafer can be carried out when the projection directions are the same.

[0045] In some other cases, the angular magnitudes of the first projection direction and the third projection direction are different, and the first projection direction and the third projection direction intersect in space; the angular magnitudes of the second projection direction and the fourth projection direction are different, and the second projection direction and the fourth projection direction intersect in space; as long as the spatial intersection position is not on the wafer, it is also possible to achieve the projection positions of the first position to be measured and the second position to be measured on the front or back surface of the wafer to be staggered from each other. It can be understood that since different types of defects have different sensitivities to light with different irradiation angles, bright-field or dark-field detection can be performed on the characteristics of different types of defects on the front and back surfaces of the wafer when the projection directions are different.

[0046] Further, the relationship between the first projection direction and the second projection direction, and the relationship between the third projection direction and the fourth projection direction can be as Figure 1 shown, the angle of the first projection direction relative to the wafer normal is less than the angle of the second projection direction relative to the wafer normal, and the angle of the third projection direction relative to the wafer normal is less than the angle of the fourth projection direction relative to the wafer normal. Of course, there can also be other situations, such as the angle of the first projection direction relative to the wafer normal is greater than the angle of the second projection direction relative to the wafer normal, and the angle of the third projection direction relative to the wafer normal is greater than the angle of the fourth projection direction relative to the wafer normal. This embodiment does not make any restrictions.

[0047] In another specific embodiment, in order to improve the detection performance of the front and back surface detection system of the wafer, a system optical structure is constructed as Figure 3 shown. The first light source module 21 includes a first bright-field illumination unit 211, and the first illumination light emitted by the first bright-field illumination unit 211 irradiates the first position to be measured in the first projection direction; the second light source module 31 includes a second bright-field illumination unit 311, and the third illumination light emitted by the second bright-field illumination unit 311 irradiates the second position to be measured in the third projection direction; the first projection direction and the third projection direction here are different, and by configuring the spatial intersection position, the projection positions of the first position to be measured and the second position to be measured on the front or back surface of the wafer are made to coincide.

[0048] Further, the first light source module 21 further includes a first dark-field illumination unit 212, and the second illumination light emitted by the first dark-field illumination unit 212 irradiates the first position to be measured in the second projection direction; the second light source module 31 further includes a second dark-field illumination unit 312, and the fourth illumination light emitted by the second dark-field illumination unit 312 irradiates the second position to be measured in the fourth projection direction; the second projection direction and the fourth projection direction here are different, and by configuring the spatial intersection position, the projection positions of the first position to be measured and the second position to be measured on the front or back surface of the wafer are made to coincide.

[0049] It should be noted that in Figure 3In [the device], by adjusting the tilt angles of the first light source module 21 and the second light source module 31, the light projection directions of the first light source module 21 and the second light source module 31 can be made different, and the projection directions can cross in space. When the crossing position is on the wafer, the projected positions of the first and second positions to be measured on the front or back surface of the wafer will coincide.

[0050] In some other cases, when the crossing position is not on the wafer, the projected positions of the first and second positions to be measured on the front or back surface of the wafer will be offset from each other. It can be understood that if the projection directions are different and the projected positions are offset from each other, the illumination lights on the front and back surfaces of the wafer will not be in a situation of opposite shooting, and a better imaging effect of the illumination spot can be obtained.

[0051] In Figure 1 or Figure 3 In the embodiments of [the device], the first bright-field illumination unit 211, the first dark-field illumination unit 212, the second bright-field illumination unit 311, and the second dark-field illumination unit 312 can use light sources of a variety of different colors, such as white light sources, yellow light sources, red light sources, etc., and even white light sources and laser light sources. This embodiment does not make any restrictions. In addition, in order to improve the detection performance, the first bright-field illumination unit 211, the first dark-field illumination unit 212, the second bright-field illumination unit 311, and the second dark-field illumination unit 312 of this embodiment can use light sources with different spectral bands according to the wafer detection requirements.

[0052] Furthermore, when performing wafer detection, when the first bright-field illumination unit 211 or the first dark-field illumination unit 212 is turned on, the second bright-field illumination unit 311 or the second dark-field illumination unit 312 is turned on synchronously; the first illumination light, the second illumination light, the third illumination light, and the fourth illumination light are all linear light beams, and the length direction of the linear light beam is perpendicular to the moving direction of the wafer.

[0053] It should be noted that the method of oblique illumination is likely to cause the deformation of the spot shape, thereby affecting the image uniformity. Therefore, in this embodiment, by using narrow-band line light sources for the first illumination light, the second illumination light, the third illumination light, and the fourth illumination light, and making the length direction of the narrow-band line light source perpendicular to the linear moving direction of the wafer, the narrow-band line light source emits a linear light beam. Compared with a circular spot light source, it can reduce the illumination width of the light source, avoid the deformation of the spot, improve the imaging brightness, improve the image uniformity, and thus improve the image quality.

[0054] Specifically, this embodiment provides multiple ways to detect the front and back sides of a wafer. For example, the first bright-field illumination unit 211 and the second bright-field illumination unit 311 can be controlled to turn on simultaneously to perform bright-field image scanning on the front and back sides of the wafer; or the first bright-field illumination unit 211 and the second dark-field illumination unit 312 can be controlled to turn on simultaneously to perform bright-field image scanning on the front side of the wafer and dark-field image scanning on the back side of the wafer; or the first dark-field illumination unit 212 and the second bright-field illumination unit 311 can be controlled to turn on simultaneously to perform dark-field image scanning on the front side of the wafer and bright-field image scanning on the back side of the wafer; the first dark-field illumination unit 212 and the second dark-field illumination unit 312 can be controlled to turn on simultaneously to perform dark-field image scanning on the front and back sides of the wafer. When detecting the front and back sides of the wafer, any one or more of the above detection methods can be used, and the present invention does not make any restrictions.

[0055] Further, in order to facilitate adjusting the positions of the illumination spots on the front and back sides of the wafer, based on the above embodiment, in other embodiments, as Figure 1 or Figure 3 shown, both the first bright-field illumination unit 211 and the second bright-field illumination unit 311 are provided with corresponding adjusting devices for making the first projection direction of the first illumination light and the third projection direction of the third illumination light fall within a first preset angle range by adjusting at least one of the pitch angle, horizontal position, and vertical position. And / or, the first dark-field illumination unit 212 and the second dark-field illumination unit 312 are provided with corresponding adjusting devices for making the second projection direction of the second illumination light and the fourth projection direction of the fourth illumination light fall within a second preset angle range by adjusting at least one of the pitch angle, horizontal position, and vertical position. Wherein, the first preset angle range and the second preset angle range are preset.

[0056] Specifically, the first bright-field illumination unit 211 includes a first bright-field light source 2111 and a first bright-field adjusting device 2112. The first bright-field light source 2111 is disposed on the first bright-field adjusting device 2112. The first bright-field light source 2111 is used to emit the first illumination light, and the first bright-field adjusting device 2112 is used to make the first projection direction of the first illumination light fall within the first preset angle range by adjusting at least one of the pitch angle, horizontal position, and vertical position.

[0057] For example, the first dark-field illumination unit 212 includes a first dark-field light source 2121 and a first dark-field adjusting device 2122. The first dark-field light source 2121 is disposed on the first dark-field adjusting device 2122. The first dark-field light source 2121 is used to emit the second illumination light, and the first dark-field adjusting device 2122 is used to make the second projection direction of the second illumination light fall within the second preset angle range by adjusting at least one of the pitch angle, horizontal position, and vertical position.

[0058] For example, the second bright-field illumination unit 311 includes a second bright-field light source 3111 and a second bright-field adjustment device 3112. The second bright-field light source 3111 is disposed on the second bright-field adjustment device 3112. The second bright-field light source 3111 is configured to emit third illumination light, and the second bright-field adjustment device 3112 is configured to adjust at least one of the pitch angle, horizontal position, and vertical position such that the third projection direction of the third illumination light is within a first preset angular range.

[0059] For example, the second dark-field illumination unit 312 includes a second dark-field light source 3121 and a second dark-field adjustment device 3122. The second dark-field light source 3121 is disposed on the second dark-field adjustment device 3122. The second dark-field light source 3121 is configured to emit fourth illumination light, and the second dark-field adjustment device 3122 is configured to adjust at least one of the pitch angle, horizontal position, and vertical position such that the fourth projection direction of the fourth illumination light is within a second preset angular range.

[0060] Further, as Figure 1 shown, the first camera module 22 includes a first imaging lens 221, a first line array camera 222, and a first camera adjustment device 223. The first imaging lens 221 is configured to receive the reflected light of the first illumination light on the wafer surface or the scattered light of the second illumination light on the wafer surface, and transmit the received light beam to the first line array camera 222. The first camera adjustment device 223 is configured to adjust at least one of the pitch angle, horizontal position, and vertical position of the first imaging lens 221 such that the optical axis of the first imaging lens 221 is symmetric with respect to the normal of the wafer surface to the optical axis of the first bright-field illumination unit 211.

[0061] And / or, the second camera module 32 includes a second imaging lens 321, a second line array camera 322, and a second camera adjustment device 323. The second imaging lens 321 is configured to receive the reflected light of the third illumination light on the wafer surface or the scattered light of the fourth illumination light on the wafer surface, and transmit the received light beam to the second line array camera 322. The second camera adjustment device 323 is configured to adjust at least one of the pitch angle, horizontal position, and vertical position of the second imaging lens 321 such that the optical axis of the second imaging lens 321 is symmetric with respect to the normal of the wafer surface to the optical axis of the second bright-field illumination unit 311.

[0062] Specifically, before wafer inspection, first, turn on the first bright-field light source 2111 and the second bright-field light source 3111 simultaneously, and use the first linear array camera 222 and the second linear array camera 322 to observe the bright-field imaging effects of the front and back sides of the wafer in real time. When back reflection occurs due to the opposite irradiation of the first bright-field light source 2111 and the second bright-field light source 3111, the position of the first bright-field light source 2111 can be adjusted by the first bright-field adjustment device 2112 along the first direction parallel to the front side of the wafer towards one end (such as the left end), and the position of the first linear array camera 222 can be adjusted by the first camera adjustment device 223 along the first direction parallel to the front side of the wafer towards one end (such as the left end). At the same time, the position of the second bright-field light source 3111 can be adjusted by the second bright-field adjustment device 3112 along the first direction parallel to the back side of the wafer towards the other end (such as the right end), and the position of the second linear array camera 322 can be adjusted by the second camera adjustment device 323 along the first direction parallel to the back side of the wafer towards the other end (such as the right end), so that the bright-field light source illumination spots on the front and back sides of the wafer are staggered from each other. After the illumination spots are staggered from each other, the positions of the first bright-field light source 2111 and the first linear array camera 222 are adjusted by the first bright-field adjustment device 2112 and the first camera adjustment device 223 along the second direction (perpendicular to the first direction) parallel to the front side of the wafer towards one end (such as the front end), and the positions of the second bright-field light source 3111 and the second linear array camera 322 are adjusted by the second bright-field adjustment device 3112 and the second camera adjustment device 323 along the second direction (perpendicular to the first direction) parallel to the back side of the wafer towards the other end (such as the back end), so that the illumination light output by the first bright-field light source 2111 and the second bright-field light source 3111 does not irradiate in opposite directions either. Through the above operations, the bright-field illumination spots on the front and back sides of the wafer can be staggered from each other in physical space, and the projection directions of the illumination light emitted by the first light source module and the second light source module can also be different. Even in the case of light transmission or light leakage, it will not interfere with the bright-field imaging of the front and back sides of the wafer.

[0063] Then, turn off the first bright-field light source 2111 and the second bright-field light source 3111, turn on the first dark-field light source 2121 and the second dark-field light source 3121, and use the first linear array camera 222 and the second linear array camera 322 to observe the dark-field imaging effects of the front and back sides of the wafer in real time. When there is reflection during the opposite irradiation of the first dark-field light source 2121 and the second dark-field light source 3121, finely adjust the angles of the first dark-field adjustment device 2122 and the second dark-field adjustment device 3122 so that the light emitted by the first dark-field light source 2121 and the second dark-field light source 3121 is not in the same optical path and the scattered light energy they emit can be respectively irradiated into the first linear array camera 222 and the second linear array camera 322. Then rotate the first camera adjustment device 223 along the third direction (such as counterclockwise), and at the same time rotate the second camera adjustment device 323 along the fourth direction (such as clockwise), and continue to keep the first linear array camera 222 and the second linear array camera 322 staggered by a certain angle to avoid the angular yaw of the first linear array camera 222 and the second linear array camera 322 due to mechanical vibration during long-term operation, which may lead to interference in imaging. Through the above operations, the dark-field illumination spots on the front and back sides of the wafer can be staggered in physical space, and the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module can also be different, so that even in the case of light transmission or light leakage, it will not interfere with the dark-field imaging of the front and back sides of the wafer.

[0064] After the positions of the first bright-field light source 2111, the second bright-field light source 3111, the first dark-field light source 2121, the second dark-field light source 3121, the first linear array camera 222 and the second linear array camera 322 are adjusted so that the illumination spots are staggered from each other or the projection directions of the illumination light are staggered, and all reflections are eliminated, the wafer front and back detection system can be used to perform bright-field scanning imaging and dark-field scanning imaging on the wafer.

[0065] Furthermore, in order to improve the detection ability for different defect types, based on the above embodiments, in other embodiments, such as Figure 4 and Figure 5 shown, the first light source module 21 further includes a third dark-field irradiation unit 213. The third dark-field irradiation unit 213 is symmetrically arranged with the first dark-field irradiation unit 211 with respect to the normal line of the wafer surface. The third dark-field irradiation unit 213 is used to emit the fifth illumination light, and the spot areas of the fifth illumination light and the second illumination light on the wafer surface overlap.

[0066] The second light source module 31 further includes a fourth dark-field irradiation unit 313. The fourth dark-field irradiation unit 313 is symmetrically arranged with the second dark-field irradiation unit 311 with respect to the normal line of the wafer surface. The fourth dark-field irradiation unit 313 is used to emit the sixth illumination light, and the spot areas of the sixth illumination light and the fourth illumination light on the wafer surface overlap.

[0067] Specifically, by adding another set of dark-field illumination units to the front and back sides of the wafer respectively, different illumination schemes can be set according to the characteristics of the sample, so as to further improve the defect detection ability of the front and back sides inspection system of the wafer. For example, the first bright-field illumination unit 211 and the first dark-field illumination unit 212 are used on the front side of the wafer, and the second bright-field illumination unit 311 and the fourth dark-field illumination unit 313 are used on the back side of the wafer, so as to effectively detect according to the pattern characteristics of the front and back sides of the wafer.

[0068] Furthermore, the third dark-field illumination unit 213 includes a third dark-field light source 2131 and a third dark-field adjustment device 2132. The third dark-field light source 2131 is used to emit the fifth illumination light, and the third dark-field adjustment device 2132 is used to make the fifth projection direction of the fifth illumination light fall within a second preset angle range by adjusting at least one of the pitch angle, horizontal position, and vertical position.

[0069] The fourth dark-field illumination unit 313 includes a fourth dark-field light source 3131 and a fourth dark-field adjustment device 3132. The fourth dark-field light source 3131 is used to emit the sixth illumination light, and the fourth dark-field adjustment device 3132 is used to make the sixth projection direction of the sixth illumination light fall within a second preset angle range by adjusting at least one of the pitch angle, horizontal position, and vertical position. Further, as Figure 1 shown, the carrier driving stage 1 includes a carrier part 11 and a driving part 12. The carrier part 11 is arranged on the driving part 12. The carrier part 11 is used to carry and define the wafer, and the driving part 12 is used to drive the carrier part 11 to drive the wafer to move linearly.

[0070] Among them, the driving part 12 includes one or more servo driving motors and one or more wafer carriers or vacuum suction cups. The vacuum suction cup is arranged on the output end of the servo driving motor and is used to adsorb and fix the wafer. The servo driving motor is used to drive the vacuum suction cup to move linearly.

[0071] Figure 6 is a schematic structural diagram of the front and back sides inspection method of the wafer in an embodiment of the present invention. The front and back sides inspection method of the wafer is applied to the front and back sides inspection system of the wafer in one of the above embodiments. The front and back sides inspection system of the wafer includes: a carrier driving stage, a first scanning system, a second scanning system, and an analysis module. The first scanning system includes a first light source module and a first camera module. The second scanning system includes a second light source module and a second camera module. As Figure 6 shown, the front and back sides inspection method of the wafer includes:

[0072] Step S1: Load the wafer to be detected onto the carrier driving stage.

[0073] Step S2: The first light source module is turned on and emits illumination light to the first position to be measured on the front side of the wafer, the second light source module is turned on and emits illumination light to the second position to be measured on the back side of the wafer, the projected positions of the first position to be measured and the second position to be measured on the front or back side of the wafer are staggered from each other, or the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module are different.

[0074] Step S3: The carrier driving stage drives the wafer to perform a linear motion.

[0075] Step S4: The first camera module collects an image of the front side of the wafer to obtain a first scanning result, and the second camera module collects an image of the back side of the wafer to obtain a second scanning result.

[0076] Step S5: The analysis module analyzes the first scanning result and the second scanning result to obtain the detection result of the wafer.

[0077] It should be noted that for the detailed content of steps S1 to S5 in this embodiment, please refer to the description in the above embodiment of the wafer front and back detection system, and will not be elaborated here.

[0078] The wafer front and back detection method of this embodiment avoids the problem of mutual interference of light beams generated during the synchronous detection of the front and back sides of the wafer by staggering the illumination spots on the front and back sides of the wafer, or by making the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module different, thereby improving the accuracy of the wafer detection result.

[0079] Furthermore, this embodiment provides multiple detection modes. Therefore, step S2 specifically includes:

[0080] The first bright field illumination unit is turned on and emits the first illumination light to the first position to be measured on the front side of the wafer, or the first dark field illumination unit is turned on and emits the second illumination light to the first position to be measured on the front side of the wafer; and,

[0081] The second bright field illumination unit is synchronously turned on and emits the third illumination light to the second position to be measured on the back side of the wafer, or the second dark field illumination unit is synchronously turned on and emits the fourth illumination light to the second position to be measured on the back side of the wafer.

[0082] Specifically, in this embodiment, the first bright-field illumination unit and the second bright-field illumination unit can be controlled to turn on simultaneously to perform bright-field image scanning on the front and back sides of the wafer at the same time; alternatively, the first bright-field illumination unit and the second dark-field illumination unit can be controlled to turn on simultaneously to perform bright-field image scanning on the front side of the wafer and dark-field image scanning on the back side of the wafer; alternatively, the first dark-field illumination unit and the second bright-field illumination unit can be controlled to turn on simultaneously to perform dark-field image scanning on the front side of the wafer and bright-field image scanning on the back side of the wafer; the first dark-field illumination unit and the second dark-field illumination unit can be controlled to turn on simultaneously to perform dark-field image scanning on the front and back sides of the wafer at the same time; when detecting the front and back sides of the wafer, any one or more of the above detection methods can be adopted, and this embodiment does not make any restrictions.

[0083] The above are only the implementation manners of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A wafer front and back side inspection system, characterized in that: It includes: A load-carrying drive stage, used to load the wafer and perform linear movement; A first scanning system is disposed on one side of the wafer, the first scanning system comprises a first light source module and a first camera module, the first light source module emits illumination light to a first position to be measured on the front side of the wafer, and the first camera module is used to capture an image of the front side of the wafer to obtain a first scanning result; A second scanning system is arranged on the other side of the wafer, the second scanning system comprises a second light source module and a second camera module, the second light source module emits illumination light to a second position to be measured on the back side of the wafer, and the second camera module is used to collect an image of the back side of the wafer to obtain a second scanning result; an analysis module, electrically connected to the first scanning system and the second scanning system respectively, and configured to analyze the first scanning result and the second scanning result to obtain a detection result of the wafer; The projection positions of the first position to be measured and the second position to be measured on the front side or the back side of the wafer are staggered, or the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module are different.

2. The wafer front and back side inspection system according to claim 1, characterized in that: The first light source module comprises a first bright field irradiation unit, and the first illumination light emitted by the first bright field irradiation unit is irradiated to the first position to be measured in a first projection direction; The second light source module comprises a second bright field irradiation unit, and the third illumination light emitted by the second bright field irradiation unit is irradiated to the second position to be measured in a third projection direction; The first projection direction and the third projection direction have the same angle relative to the wafer normal, the first projection direction and the third projection direction are parallel in space, and are spaced by a first preset distance so that the projection positions of the first position to be measured and the second position to be measured on the front side or the back side of the wafer are staggered.

3. The wafer front and back side inspection system according to claim 2, characterized in that: The first light source module further includes a first dark field irradiation unit, and the second illumination light emitted by the first dark field irradiation unit is irradiated to the first position to be measured in a second projection direction; The second light source module further includes a second dark field irradiation unit, and the fourth illumination light emitted by the second dark field irradiation unit is irradiated to the second position to be measured in a fourth projection direction; The second projection direction and the fourth projection direction have the same angle relative to the wafer normal, the second projection direction and the fourth projection direction are parallel in space, and the projection positions of the first position to be measured and the second position to be measured on the front side or the back side of the wafer are staggered by a second preset distance.

4. The wafer front and back side inspection system according to claim 1, characterized in that: The first light source module comprises a first bright field irradiation unit, and the first illumination light emitted by the first bright field irradiation unit is irradiated to the first position to be measured in a first projection direction; The second light source module comprises a second bright field irradiation unit, and the third illumination light emitted by the second bright field irradiation unit is irradiated to the second position to be measured in a third projection direction; The first projection direction is different from the third projection direction, and the spatial intersection position is configured so that the projection positions of the first position to be measured and the second position to be measured on the front side or the back side of the wafer overlap or are staggered.

5. The wafer front and back side inspection system according to claim 4, characterized in that: The first light source module further includes a first dark field irradiation unit, and the second illumination light emitted by the first dark field irradiation unit is irradiated to the first position to be measured in a second projection direction; The second light source module further includes a second dark field irradiation unit, and the fourth illumination light emitted by the second dark field irradiation unit is irradiated to the second position to be measured in a fourth projection direction; The second projection direction is different from the fourth projection direction, and the spatial intersection position is configured so that the projection positions of the first position to be measured and the second position to be measured on the front side or the back side of the wafer overlap or are staggered.

6. The wafer front and back side inspection system according to claim 3 or 5, characterized in that: When the first bright field illumination unit is turned on, the second bright field illumination unit is turned on synchronously; or, when the first dark field illumination unit is turned on, the second dark field illumination unit is turned on synchronously; The first illumination light, the second illumination light, the third illumination light, and the fourth illumination light are all linear light beams, and the length direction of the linear light beam is perpendicular to the moving direction of the wafer.

7. The wafer front and back side inspection system according to claim 3 or 5, characterized in that: The first bright field illumination unit and the second bright field illumination unit both have corresponding adjustment devices for adjusting at least one of a pitch angle, a horizontal position, and a vertical position so that the first projection direction of the first illumination light and the third projection direction of the third illumination light are within a first preset angle range; and / or, The first dark field illumination unit and the second dark field illumination unit have corresponding adjustment devices, which are used to adjust at least one of the pitch angle, the horizontal position, and the vertical position so that the second projection direction of the second illumination light and the fourth projection direction of the fourth illumination light are within a second preset angle range.

8. The wafer front and back side inspection system according to claim 7, characterized in that: The first camera module includes a first imaging lens, a first line array camera and a first camera adjustment device, the first imaging lens is used to receive the reflected light of the first illumination light on the wafer surface or the scattered light of the second illumination light on the wafer surface, and transmit the received light beam to the first line array camera, the first camera adjustment device is used to adjust at least one of the pitch angle, horizontal position and vertical position of the first imaging lens, so that the optical axis of the first imaging lens and the optical axis of the first bright field illumination unit are symmetrical about the normal line of the wafer surface; and / or, The second camera module includes a second imaging lens, a second line array camera and a second camera adjustment device. The second imaging lens is used to receive the reflected light of the third illumination light on the wafer surface or the scattered light of the fourth illumination light on the wafer surface, and transmit the received light beam to the second line array camera. The second camera adjustment device is used to adjust at least one of the pitch angle, horizontal position and vertical position of the second imaging lens so that the optical axis of the second imaging lens and the optical axis of the second bright field illumination unit are symmetrical about the normal of the wafer surface.

9. The wafer front and back side inspection system according to claim 3 or 5, characterized in that: The first light source module further includes a third dark field illumination unit, the third dark field illumination unit and the first dark field illumination unit are symmetrically arranged about the normal line of the wafer surface, the third dark field illumination unit is used to emit a fifth illumination light, and the fifth illumination light and the second illumination light overlap in a spot area on the wafer surface; and / or, The second light source module also includes a fourth dark field illumination unit, which is symmetrically arranged with the second dark field illumination unit about the normal line of the wafer surface, and the fourth dark field illumination unit is used to emit a sixth illumination light, and the sixth illumination light and the fourth illumination light overlap in a spot area on the wafer surface.

10. The wafer front and back side inspection system according to claim 1, characterized in that: The carrying and driving platform includes a carrying part and a driving part, wherein the carrying part is arranged on the driving part, the carrying part is used to carry and limit the wafer, and the driving part is used to drive the carrying part to move so as to drive the wafer to move linearly.

11. A wafer front and back side inspection method, characterized in that: The method is applied to the wafer front and back side inspection system according to any one of claims 1 to 10; the method comprises: Loading the wafer to be inspected onto the carrying drive stage; The first light source module is turned on and emits illumination light to a first position to be measured on the front side of the wafer, and the second light source module is turned on and emits illumination light to a second position to be measured on the back side of the wafer; the first position to be measured and the second position to be measured are staggered from each other along the projection positions on the front side or the back side of the wafer, or the projection directions of the illumination light emitted by the first light source module and the illumination light emitted by the second light source module are different; The carrier driving stage drives the wafer to perform linear motion; The first camera module collects an image of the front side of the wafer to obtain a first scanning result, and the second camera module collects an image of the back side of the wafer to obtain a second scanning result; The analysis module analyzes the first scanning result and the second scanning result to obtain a detection result of the wafer.

Images