Wafer detection method and wafer detection system

Abstract

The present application provides a wafer detection method and a wafer detection system, which obtains a first light spot position and a second light spot position detected by a detector; based on the first light spot position and the second light spot position, adjusts the first inclination of the auxiliary reflector so that the first light spot position and the second light spot position coincide with each other; adjusts the first axial distance of the auxiliary reflector through the Michelson interference fringes detected by the detector; adds a reference objective lens, a measuring objective lens and a third lens to the optical path, and adjusts the second inclination and the first eccentric distance of the reference objective lens through the detected Linnik interference fringes; replaces the auxiliary reflector with a reference reflector, and the reference reflector and the reference objective lens are fixed on the same mechanical part. By additionally introducing an independent auxiliary reflector, the auxiliary reflector has a higher degree of freedom in deployment, will not be interfered by the reference objective lens, can achieve the decoupling of the adjustment dimensions of the reference objective lens and the reference reflector, and improve the adjustment efficiency and accuracy.

Description

Technical Field

[0001] The present application relates to the field of wafer detection, and in particular to a wafer detection method and a wafer detection system. Background Art

[0002] In the semiconductor manufacturing process, it is often necessary to use a wafer detection system to detect the wafer. The wafer detection system includes a reference optical path composed of a reference objective lens and a reference reflector, and a measurement optical path composed of a measuring objective lens and a wafer to be tested. The wafer to be tested is placed under the measuring objective lens, and the wafer is detected by observing the interference fringes generated by the focusing system. In the related art, in the reference optical path, the reference reflector is installed on the mechanical part of the reference objective lens. During the adjustment, the adjustment dimensions of the reference objective lens and the reference reflector are coupled, and the two need to be adjusted back and forth repeatedly to adjust the interference fringes. For example, the reference objective lens is adjusted first, then the reference reflector is adjusted, and then the reference objective lens is adjusted again until the interference fringes are adjusted. The adjustment complexity is high, and the adjustment efficiency and accuracy are low. Summary of the invention

[0003] In view of this, the purpose of this application is to provide a wafer detection method and a wafer detection system, which can achieve the decoupling of the adjustment dimensions of the reference objective lens and the reference reflector, and improve the adjustment efficiency and accuracy. The specific scheme is as follows:

[0004] In one aspect, the present application provides a wafer inspection method, the method comprising:

[0005] When the light source (101), the first lens (102), the beam splitter (103), the wafer to be tested (105), the second lens (108) and the detector (111) are configured to be located in an optical path, a first light spot position detected by the detector (111) is obtained; and when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the second lens (108) and the detector (111) are configured to be located in an optical path, a second light spot position detected by the detector (111) is obtained;

[0006] Based on the first light spot position and the second light spot position, adjusting a first inclination of the auxiliary reflector (1071) so that the first light spot position and the second light spot position coincide with each other;

[0007] When the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be tested (105), the second lens (108) and the detector (111) are arranged in an optical path, adjusting a first axial distance of the auxiliary reflector (1071) by means of Michelson interference fringes detected by the detector (111);

[0008] When the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be measured (105), the second lens (108), the detector (111), the reference objective lens (106), the measuring objective lens (104) and the third lens (110) are arranged in an optical path, a second inclination and a first eccentricity of the reference objective lens (106) are adjusted by detecting Linnik interference fringes;

[0009] The auxiliary reflector (1071) is replaced by a reference reflector (1072), and the reference reflector (1072) and the reference objective lens (106) are fixed on the same mechanical part.

[0010] Specifically, replacing the auxiliary reflector (1071) with a reference reflector (1072) comprises:

[0011] After adjusting the first inclination of the auxiliary reflector (1071), emitting light with a calibration mark to the auxiliary reflector (1071) through an autocollimator (113), and recording the position of the returned calibration mark;

[0012] Based on the position of the returned calibration mark, the auxiliary reflector (1071) is replaced with the reference reflector (1072) so that the position of the returned calibration mark remains unchanged.

[0013] Specifically, when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be tested (105), the second lens (108), and the detector (111) are arranged in an optical path, adjusting a first axial distance of the auxiliary reflector (1071) by using Michelson interference fringes detected by the detector (111), comprises:

[0014] When a single-mode laser light source (1012), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be tested (105), the second lens (108) and the detector (111) are arranged in an optical path, a first axial distance of the auxiliary reflector (1071) is adjusted with a first adjustment step length based on Michelson interference fringes detected by the detector (111);

[0015] The single-mode laser light source (1012) is replaced with a white light source (1011), and the first axial distance of the auxiliary reflector (1071) is adjusted with a second adjustment step length based on the Michelson interference fringes detected by the detector (111); the second adjustment step length is smaller than the first adjustment step length.

[0016] Specifically, when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be measured (105), the second lens (108), the detector (111), the reference objective lens (106), the measuring objective lens (104) and the third lens (110) are arranged in an optical path, adjusting the second inclination and the first eccentricity of the reference objective lens (106) by detecting Linnik interference fringes, comprises:

[0017] When the surface light source (114), the measuring objective lens (104), the beam splitter (103), the second lens (108), the third lens (110), and the detector (111) are arranged in an optical path, obtaining a first entrance pupil position detected by the detector (111), wherein the measuring objective lens (104) is located on the optical path between the surface light source (114) and the beam splitter (103), and the third lens (110) is located on the optical path between the beam splitter (103) and the detector (111);

[0018] When the surface light source (114), the reference objective lens (106), the beam splitter (103), the second lens (108), the third lens (110), and the detector (111) are arranged in an optical path, obtaining a second entrance pupil position detected by the detector (111), wherein the reference objective lens (106) is located in the optical path between the surface light source (114) and the beam splitter (103);

[0019] Based on the first entrance pupil position and the second entrance pupil position, adjusting the first eccentric distance of the reference objective lens (106) so that the first entrance pupil position and the second entrance pupil position coincide with each other;

[0020] When the light source (101), the first lens (102), the beam splitter (103), the reference objective lens (106), the auxiliary reflector (1071), the measuring objective lens (104), the wafer to be measured (105), the second lens (108), the third lens (110) and the detector (111) are arranged in an optical path, the second inclination and the first eccentricity of the reference objective lens (106) are adjusted by detecting Linnik interference fringes.

[0021] Specifically, the method further includes:

[0022] When the light with the calibration mark emitted by the autocollimator (113) passes through the first lens (102), the beam splitter (103) and the reference objective lens (106) and is incident on the auxiliary reflector (1071), the second axial distance of the reference objective lens (106) is adjusted according to the focus clarity of the calibration mark detected by the detector (111).

[0023] Specifically, replacing the auxiliary reflector (1071) with the reference reflector (1072) comprises:

[0024] The auxiliary reflector (1071) is replaced by the reference reflector (1072), and the second axial distance of the reference reflector (1072) is adjusted with a third adjustment step length based on the focal plane position of the reference objective lens (106);

[0025] Based on the Linnik interference fringes detected by the detector (111), the second axial distance is adjusted with a fourth adjustment step length so that the second axial distance is equal to the first axial distance; the fourth adjustment step length is smaller than the third adjustment step length.

[0026] In another aspect, an embodiment of the present application further provides a wafer inspection system, the system comprising:

[0027] A light source (101), a beam splitter (103), a measuring objective lens (104), a reference objective lens (106), and a detector (111); the beam splitter (103) is used to split the light emitted by the light source (101) into a measuring light beam propagating in a measuring light path where the measuring objective lens (104) is located, and a reference light beam propagating in a reference light path where the reference objective lens (106) is located;

[0028] A first lens (102) is arranged on the optical path between the light source (101) and the beam splitter (103);

[0029] A second lens (108) and a third lens (110) are both arranged on the optical path between the beam splitter (103) and the detector (111);

[0030] An auxiliary reflector (1071), arranged on the light-emitting side of the reference objective lens (106), and used for reflecting the reference light beam;

[0031] A wafer to be measured (105), arranged on the light-emitting side of the measuring objective lens (104), and used for reflecting the measuring light beam;

[0032] The detector (111) is used to detect interference fringes formed after the reflected measurement beam and the reflected reference beam pass through the beam splitter (103);

[0033] A reference reflector (1072), the reference reflector (1072) and the reference objective lens (106) being fixed on the same mechanical part, and being used to replace the auxiliary reflector (1071) after the detector (111) detects the interference fringes, so as to detect the wafer (105) to be tested.

[0034] Specifically, the system further comprises an autocollimator (113);

[0035] The autocollimator (113) is used to emit light with a calibration mark to the auxiliary reflector (1071) after the interference fringes are formed, and to record the position of the returned calibration mark, so that after the auxiliary reflector (1071) is replaced by the reference reflector (1072), the position of the returned calibration mark remains unchanged.

[0036] Specifically, the light source (101) comprises a single-mode laser light source (1012) and a white light source (1011);

[0037] The single-mode laser light source (1012) is used to adjust the first axial distance of the auxiliary reflector (1071) with a first adjustment step length through Michelson interference fringes when emitting laser light;

[0038] The white light source (1011) is used to adjust the first axial distance of the auxiliary reflector (1071) with a second adjustment step length through Michelson interference fringes when emitting white light; the second adjustment step length is smaller than the first adjustment step length.

[0039] Specifically, the system further includes:

[0040] an auxiliary beam splitter (109), arranged between the second lens (108) and the third lens (110);

[0041] An auxiliary detector (112) is used to image the light passing through the auxiliary beam splitter (109).

[0042] The embodiment of the present application provides a wafer detection method and a wafer detection system, wherein when a light source (101), a first lens (102), a beam splitter (103), a wafer to be tested (105), a second lens (108), and a detector (111) are configured to be located in an optical path, a first light spot position detected by the detector (111) is obtained; and when a light source (101), a first lens (102), a beam splitter (103), an auxiliary reflector (1071), a second lens (108), and a detector (111) are configured to be located in an optical path, a second light spot position detected by the detector (111) is obtained; based on the first light spot position and the second light spot position, a first inclination of the auxiliary reflector (1071) is adjusted so that the first light spot position and the second light spot position coincide with each other; when a light source (101), a first lens (102), a beam splitter (103), an auxiliary reflector (1071), a second lens (108), and a detector (111) are configured to be located in an optical path, a first light spot position detected by the detector (111) is obtained. When the reflector (1071), the wafer to be measured (105), the second lens (108), and the detector (111) are located in an optical path, the first axial distance of the auxiliary reflector (1071) is adjusted by the Michelson interference fringes detected by the detector (111); when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be measured (105), the second lens (108), the detector (111), the reference objective lens (106), the measuring objective lens (104), and the third lens (110) are configured to be located in an optical path, the second inclination and the first eccentric distance of the reference objective lens (106) are adjusted by the detected Linnik interference fringes; the auxiliary reflector (1071) is replaced by a reference reflector (1072), and the reference reflector (1072) and the reference objective lens (106) are fixed on the same mechanical part. In short, by introducing an additional independent reflector, namely the auxiliary reflector, the auxiliary reflector has a higher degree of freedom in adjustment and will not be disturbed by the reference objective lens. It can determine its own axial position (namely the first axial distance) and degree of inclination (namely the first inclination). In addition, it can also help adjust the posture of the reference objective lens in the future, that is, determine the second inclination and the first eccentric distance. In this way, after the auxiliary reflector has been able to help adjust the interference fringes, it can be replaced by the reference reflector, thereby realizing the decoupling of the adjustment dimensions of the reference objective lens and the reference reflector, and improving the adjustment efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1A schematic diagram of a process flow of a wafer inspection method provided in an embodiment of the present application is shown;

[0045] Figure 2 A schematic diagram of an optical path for detecting the position of a first light spot provided in an embodiment of the present application is shown;

[0046] Figure 3 A schematic diagram of an optical path for detecting the position of a second light spot provided in an embodiment of the present application is shown;

[0047] Figure 4 A schematic diagram of an optical path for adjusting an auxiliary reflector provided in an embodiment of the present application is shown;

[0048] Figure 5 A schematic diagram of an optical path for adjusting a reference objective lens provided in an embodiment of the present application is shown;

[0049] Figure 6 A schematic diagram of an optical path for detecting a first entrance pupil position provided in an embodiment of the present application is shown;

[0050] Figure 7 A schematic diagram of an optical path for detecting a second entrance pupil position provided in an embodiment of the present application is shown;

[0051] Figure 8 A schematic diagram of another optical path for adjusting a reference objective lens provided in an embodiment of the present application is shown;

[0052] Fig. 9 A schematic diagram of an optical path for determining a first inclination of an auxiliary reflector provided in an embodiment of the present application is shown;

[0053] Fig.10 A schematic diagram of another optical path for adjusting a reference objective lens provided in an embodiment of the present application is shown;

[0054] Fig.11 A schematic diagram of a wafer inspection system provided by an embodiment of the present application is shown;

[0055] Fig.12 A schematic diagram of another wafer inspection system provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0056] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0057] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0058] Secondly, the present application is described in detail with reference to the schematic diagram. When describing the embodiments of the present application in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0059] As described in the background technology, in the related technology, in the reference light path, the reference reflector is installed on the mechanical parts of the reference objective lens. During adjustment, the adjustment dimensions of the reference objective lens and the reference reflector are coupled, and the two need to be adjusted back and forth repeatedly to adjust the interference fringes. For example, the reference objective lens is adjusted first, then the reference reflector is adjusted, and then the reference objective lens is adjusted again until the interference fringes are adjusted. The adjustment complexity is high, and the adjustment efficiency and accuracy are low.

[0060] Based on the above technical problems, the embodiments of the present application provide a wafer detection method and a wafer detection system. By additionally introducing an independent reflector, namely an auxiliary reflector, the auxiliary reflector has a higher degree of freedom in adjustment and will not be disturbed by the reference objective lens. It can determine its own axial position (namely the first axial distance) and degree of inclination (namely the first inclination). In addition, it can also help adjust the posture of the reference objective lens in the future, that is, determine the second inclination and the first eccentric distance. In this way, after the auxiliary reflector can help adjust the interference fringes, it is replaced by the reference reflector, thereby realizing the decoupling of the adjustment dimensions of the reference objective lens and the reference reflector, and improving the adjustment efficiency and accuracy.

[0061] To facilitate understanding, a wafer inspection method and a wafer inspection system provided in an embodiment of the present application are described in detail below with reference to the accompanying drawings.

[0062] refer to Figure 1 As shown, it is a flow chart of a wafer detection method provided in an embodiment of the present application, and the method may include the following steps.

[0063] S101, when a light source (101), a first lens (102), a beam splitter (103), a wafer to be tested (105), a second lens (108) and a detector (111) are configured to be located in an optical path, a first light spot position detected by the detector (111) is obtained; and when a light source (101), a first lens (102), a beam splitter (103), an auxiliary reflector (1071), a second lens (108) and a detector (111) are configured to be located in an optical path, a second light spot position detected by the detector (111) is obtained.

[0064] Specifically, refer to Figure 2The figure is a schematic diagram of an optical path for detecting the position of a first light spot provided in an embodiment of the present application, wherein the optical path includes a light source (101), a first lens (102), a beam splitter (103), a wafer to be tested (105), a second lens (108) and a detector (111).

[0065] Light emitted by the light source (101) passes through the first lens (102) and is incident on the beam splitter (103). The beam splitter (103) has a light splitting function and can make a part of the light incident on the surface of the wafer to be tested (105). The wafer to be tested (105) reflects the light, and the reflected light passes through the beam splitter (103) and the second lens (108) and is received by the detector (111). The detector (111) can detect the light and record the light spot position as the first light spot position.

[0066] Specifically, refer to Figure 3 The figure is a schematic diagram of an optical path for detecting the position of a second light spot provided in an embodiment of the present application, wherein the optical path includes a light source (101), a first lens (102), a beam splitter (103), an auxiliary reflector (1071), a second lens (108) and a detector (111).

[0067] The beam splitter (103) can allow a portion of the light emitted by the light source (101) to be transmitted and incident on the auxiliary reflector (1071). After the auxiliary reflector (1071) reflects the light, the light passes through the beam splitter (103) and the second lens (108) and is received by the detector (111). At this time, the light spot of the light in the detector (111) can be recorded as the second light spot position.

[0068] S102, based on the first light spot position and the second light spot position, adjusting the first inclination of the auxiliary reflector (1071) so that the first light spot position and the second light spot position coincide with each other.

[0069] Specifically, the first inclination can be understood as the angle at which the plane where the auxiliary reflector (1071) is located deviates from the vertical plane. By adjusting the first inclination, the position of the light spot in the detector (111) can be changed, that is, the adjustment of the second light spot position can be achieved.

[0070] Since the first light spot position can be understood as the light spot position in the measuring light path, and the second light spot position can be understood as the light spot position in the reference light path, the first inclination of the auxiliary reflector (1071) is adjusted to change the second light spot position. When the first light spot position and the second light spot position coincide, it can be indicated that the measuring light path and the reference light path completely coincide. That is, at this time, the inclination of the auxiliary reflector (1071) is consistent with the inclination of the wafer to be measured (105). In particular, when the plane where the wafer to be measured (105) is located is in the horizontal plane, it can be ensured that the mirror surface of the auxiliary reflector (1071) is in the vertical plane, thereby facilitating the subsequent adjustment of the interference fringes.

[0071] In actual operation, the position of the first light spot may be detected first, and then the position of the second light spot may be adjusted so that the two light spot positions coincide with each other.

[0072] S103, when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be tested (105), the second lens (108), and the detector (111) are arranged in an optical path, adjusting a first axial distance of the auxiliary reflector (1071) by using Michelson interference fringes detected by the detector (111).

[0073] Specifically, refer to Figure 4 As shown is a schematic diagram of an optical path for adjusting an auxiliary reflector provided in an embodiment of the present application, wherein the optical path includes a light source (101), a first lens (102), a beam splitter (103), an auxiliary reflector (1071), a wafer to be tested (105), a second lens (108) and a detector (111).

[0074] Specifically, after the light emitted by the light source (101) passes through the beam splitter (103), a portion of the light is incident on the wafer to be tested (105) for detection, and the other portion of the light is incident on the auxiliary reflector (1071). After the two beams of light are respectively reflected by the wafer to be tested (105) and the auxiliary reflector (1071), they pass through the beam splitter (103) and the second lens (108) and Michelson interference occurs to form Michelson interference fringes, which are then detected by the detector (111).

[0075] Specifically, the first axial distance of the auxiliary reflector (1071) can be adjusted according to the Michelson interference fringes. The first axial distance can be understood as the distance of the auxiliary reflector (1071) in the direction of light propagation, that is, the distance in the direction of the optical axis. When the interference fringes have zero-order fringes, that is, a bright fringe or a dark fringe is observed in the detector (111), it means that the auxiliary reflector (1071) has been moved to a suitable position. At this time, the distance between the auxiliary reflector (1071) and the beam splitter (103) is the same as the distance between the wafer to be tested (105) and the beam splitter (103).

[0076] In a possible implementation, the light source (101) may include a single-mode laser light source (1012) and a white light source (1011). Then, S103, when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be tested (105), the second lens (108), and the detector (111) are configured to be located in the optical path, the first axial distance of the auxiliary reflector (1071) is adjusted by using the Michelson interference fringes detected by the detector (111), which may specifically include S1031-S1032.

[0077] S1031, when a single-mode laser light source (1012), a first lens (102), a beam splitter (103), an auxiliary reflector (1071), a wafer to be tested (105), a second lens (108) and a detector (111) are arranged in an optical path, a first axial distance of the auxiliary reflector (1071) is adjusted with a first adjustment step length based on Michelson interference fringes detected by the detector (111).

[0078] Specifically, in order to adjust the first axial distance of the auxiliary reflector (1071) as quickly as possible, the single-mode laser light source (1012) and the white light source (1011) can be used for adjustment. First, the single-mode laser light source (1012) can be used for coarse adjustment, that is, adjustment is performed according to the first adjustment step, wherein the first adjustment step can be understood as the moving distance of the auxiliary reflector (1071) in the axial direction, and the moving distance can be larger. The light emitted by the single-mode laser light source (1012) is divided into two beams of light through the first lens (102) and the beam splitter (103). The two beams of light undergo Michelson interference to form interference fringes. Since the coherence length of the single-mode laser is relatively long, it is easier to adjust the interference fringes.

[0079] S1032, replacing the single-mode laser light source (1012) with a white light source (1011), and adjusting the first axial distance of the auxiliary reflector (1071) with a second adjustment step length based on the Michelson interference fringes detected by the detector (111).

[0080] Specifically, after the interference fringes are adjusted using the single-mode laser light source (1012), it can be replaced by a white light source (1011). The white light source (1011) emits white light, and interference fringes are formed between the measuring beam and the reference beam. At this time, the interference fringes are adjusted more finely, that is, adjusted according to the second adjustment step length. The second adjustment step length can also be understood as the moving distance of the auxiliary reflector (1071) in the axial direction. It is worth noting that the second adjustment step length is smaller than the first adjustment step length. As an example, the second adjustment step length can take a smaller value, that is, the moving distance during fine adjustment can be smaller. When a bright fringe or a dark fringe appears in the detector (111), it means that the first axial distance adjustment of the auxiliary reflector (1071) is completed. In this way, the first axial distance of the auxiliary reflector (1071) can be determined as soon as possible, thereby improving assembly efficiency.

[0081] S104, when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be measured (105), the second lens (108), the detector (111), the reference objective lens (106), the measuring objective lens (104) and the third lens (110) are arranged in the optical path, the second inclination and the first eccentricity of the reference objective lens (106) are adjusted according to the detected Linnik interference fringes.

[0082] Specifically, refer to Figure 5 As shown, it is a schematic diagram of an optical path for adjusting a reference objective lens provided in an embodiment of the present application. Figure 4 As for the optical path shown, a reference objective lens (106), a measuring objective lens (104) and a third lens (110) are added to the optical path to form Linnik interference.

[0083] Light emitted by a light source (101) is split by a beam splitter (103) to form a measuring beam and a reference beam. The measuring beam passes through a measuring objective lens (104) and is incident on a wafer to be measured (105). The reference beam passes through a reference objective lens (106) and is incident on an auxiliary reflector (1071). Linnick interference then occurs between the measuring beam and the reference beam, forming Linnick interference fringes.

[0084] Since the positions of the measuring objective lens (104) and the wafer to be measured (105) remain unchanged, and the position of the auxiliary reflector (1071) in the axial direction has been determined, the interference fringes can be changed by adjusting the reference objective lens (106).

[0085] The second inclination can be understood as the angle at which the plane where the reference objective lens (106) is located deviates from the vertical plane, and the first eccentric distance can be understood as the radial distance of the center of the optical axis of the reference objective lens (106) relative to a preset axis, wherein the preset axis can be understood as the direction line of the reference light beam generated after the light emitted by the light source (101) passes through the beam splitter (103).

[0086] In short, by adjusting the inclination and eccentricity of the reference objective lens (106), the position of the reference objective lens (106) and the position of the measuring objective lens (104) can be made symmetrical about the beam splitter (103). At this time, it can be observed in the detector (111) that the interference fringes are widened to only one bright fringe or only one dark fringe within the field of view, indicating that the reference objective lens (106) has been properly adjusted.

[0087] In a possible implementation, in order to improve the adjustment accuracy and efficiency of the reference objective lens (106), the eccentricity of the reference objective lens (106) can be roughly adjusted based on the entrance pupil position, and then the tilt is adjusted by interference fringes, and the eccentricity is fine-tuned at the same time. That is, S104, when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be measured (105), the second lens (108), the detector (111), the reference objective lens (106), the measuring objective lens (104) and the third lens (110) are arranged in the optical path, the second tilt and the first eccentricity of the reference objective lens (106) are adjusted by the detected Linnik interference fringes, which can specifically include S1041-S1044.

[0088] S1041, when the surface light source (114), the measuring objective lens (104), the beam splitter (103), the second lens (108), the third lens (110), and the detector (111) are arranged in the optical path, obtaining a first entrance pupil position detected by the detector (111).

[0089] Specifically, refer to Figure 6 The figure is a schematic diagram of an optical path for detecting a first entrance pupil position provided in an embodiment of the present application, wherein the optical path comprises a surface light source (114), a measuring objective lens (104), a beam splitter (103), a second lens (108), a third lens (110), and a detector (111). The measuring objective lens (104) is located on the optical path between the surface light source (114) and the beam splitter (103), and the third lens (110) is located on the optical path between the beam splitter (103) and the detector (111).

[0090] Specifically, the third lens (110) can be located on the rear focal plane of the measuring objective lens (104), and the light emitted by the surface light source (114) is received by the detector (111) after passing through the measuring objective lens (104), the beam splitter (103), the second lens (108), and the third lens (110). A light spot can be observed in the detector (111), and the position of the light spot is the first entrance pupil position. The first entrance pupil position can be understood as the entrance pupil position of the measuring objective lens (104).

[0091] S1042, when the surface light source (114), the reference objective lens (106), the beam splitter (103), the second lens (108), the third lens (110) and the detector (111) are configured to be located in the optical path, obtaining a second entrance pupil position detected by the detector (111).

[0092] Specifically, refer to Figure 7 As shown, a schematic diagram of an optical path for detecting the position of a second entrance pupil provided in an embodiment of the present application is provided, wherein the optical path includes a surface light source (114), a reference objective lens (106), a beam splitter (103), a second lens (108), a third lens (110) and a detector (111), wherein the reference objective lens (106) is located on the optical path between the surface light source (114) and the beam splitter (103).

[0093] Specifically, light emitted by the surface light source (114) passes through the reference objective lens (106), the beam splitter (103), the second lens (108), and the third lens (110) and is received by the detector (111). A light spot is observed in the detector (111), and the position of the light spot can be used as the second entrance pupil position. The second entrance pupil position can be understood as the entrance pupil position of the reference objective lens (106).

[0094] S1043: Based on the first entrance pupil position and the second entrance pupil position, adjust the first eccentric distance of the reference objective lens (106) so that the first entrance pupil position and the second entrance pupil position coincide with each other.

[0095] Specifically, the first eccentricity of the reference objective lens (106) can be adjusted, that is, the reference objective lens (106) is moved in the vertical direction, so that the second entrance pupil position coincides with the first entrance pupil position. At this time, the eccentricity of the reference objective lens (106) is consistent with the eccentricity of the measuring objective lens (104). For example, the optical axes of the two objective lenses coincide with the light transmission direction. In other words, the eccentricity of the reference objective lens (106) can be adjusted by adjusting the entrance pupil position, so that the eccentricity of the reference objective lens (106) can be quickly adjusted to a suitable range. At this time, it can be considered that the eccentricity of the reference objective lens (106) is roughly adjusted, that is, the moving distance of the reference objective lens (106) in the vertical direction during adjustment will be larger.

[0096] S1044, when the light source (101), the first lens (102), the beam splitter (103), the reference objective lens (106), the auxiliary reflector (1071), the measuring objective lens (104), the wafer to be measured (105), the second lens (108), the third lens (110) and the detector (111) are arranged in the optical path, the second inclination and the first eccentricity of the reference objective lens (106) are adjusted by detecting the Linnik interference fringes.

[0097] Specifically, refer to Figure 8 , which is a schematic diagram of another optical path for adjusting a reference objective lens provided in an embodiment of the present application, wherein the optical path includes a light source (101), a first lens (102), a beam splitter (103), a reference objective lens (106), an auxiliary reflector (1071), a measuring objective lens (104), a wafer to be measured (105), a second lens (108), a third lens (110) and a detector (111).

[0098] Specifically, light emitted by a light source (101) passes through a first lens (102) and a beam splitter (103) and is then split into two beams, namely a measuring beam and a reference beam. The measuring beam passes through a measuring objective lens (104) and is reflected by a wafer to be measured (105). The measuring beam passes through a beam splitter (103), a second lens (108) and a third lens (110) and is received by a detector (111). The reference beam passes through a reference objective lens (106) and is reflected by an auxiliary reflector (1071). The reference beam also passes through a beam splitter (103), a second lens (108) and a third lens (110) and is received by a detector (111). Linnick interference occurs between the reference beam and the measuring beam, and Linnick interference fringes are observed in the detector (111).

[0099] Specifically, by adjusting the second inclination and the first eccentricity of the reference objective lens (106), the Linnik interference fringes are widened to only one bright fringe or only one dark fringe in the detector (111), indicating that the inclination and eccentricity of the reference objective lens (106) have been adjusted. It is worth noting that the secondary adjustment of the eccentricity of the reference objective lens (106) is a fine adjustment process, and the moving distance of the reference objective lens (106) in the vertical direction will be smaller.

[0100] In summary, by making a coarse adjustment to the eccentricity of the reference objective lens (106) based on the entrance pupil position, it is convenient to adjust the Linnick interference fringes more quickly in the subsequent process, and then the tilt of the reference objective lens (106) can be quickly adjusted based on the Linnick interference fringes, and the eccentricity of the reference objective lens (106) can be finely adjusted, thereby improving the efficiency of optical path adjustment.

[0101] S105, replacing the auxiliary reflector (1071) with a reference reflector (1072), wherein the reference reflector (1072) and the reference objective lens (106) are fixed on the same mechanical component.

[0102] Specifically, since the reference reflector (1072) needs to be fixed on the same mechanical part as the reference objective lens (106), after the first inclination and the first axial distance of the auxiliary reflector (1071) are determined, the reference reflector (1072) can be directly used to replace the auxiliary reflector (1071), and the reference reflector (1072) can be installed according to the first inclination and the first axial distance, so that the inclination degree and axial position of the reference reflector (1072) are accurate.

[0103] In summary, since in the related art, the assembly dimensions of the reference objective lens and the reference reflector are coupled, it is not easy to adjust the interference fringes, and the installation efficiency and accuracy are relatively low. By introducing an additional independent reflector, namely, an auxiliary reflector, the auxiliary reflector has a higher degree of freedom in adjustment and will not be disturbed by the reference objective lens. It can determine its own axial position (namely, the first axial distance) and degree of inclination (namely, the first inclination). In addition, it can also help adjust the posture of the reference objective lens in the future, that is, determine the second inclination and the first eccentric distance. In this way, after the auxiliary reflector can help adjust the interference fringes, it is replaced by the reference reflector, thereby realizing the decoupling of the installation dimensions of the reference objective lens and the reference reflector, and improving the installation efficiency and accuracy.

[0104] In a possible implementation, S105, replacing the auxiliary reflector (1071) with the reference reflector (1072), may be specifically S1051-S1052.

[0105] S1051, after adjusting the first inclination of the auxiliary reflector (1071), emitting light with a calibration mark to the auxiliary reflector (1071) through the autocollimator (113), and recording the position of the returned calibration mark.

[0106] Specifically, refer to Fig. 9 As shown, a schematic diagram of an optical path for determining a first inclination of an auxiliary reflector provided in an embodiment of the present application is provided, wherein an autocollimator (113) is added to the optical path. After the first inclination of the auxiliary reflector (1071) is determined, the first inclination can be recorded. The autocollimator (113) can emit light with a calibration mark, such as a cross-shaped light, to the back of the auxiliary reflector (1071). After the light is reflected by the auxiliary reflector (1071), it will return to the autocollimator (113). The autocollimator (113) can record the position of the returned calibration mark, such as the position of the cross-shaped light.

[0107] S1052, based on the position of the returned calibration mark, the auxiliary reflector (1071) is replaced with the reference reflector (1072) so that the position of the returned calibration mark remains unchanged.

[0108] Specifically, after the auxiliary reflector (1071) is replaced by the reference reflector (1072), in order to confirm that the inclination of the reference reflector (1072) has reached the first inclination, the light emitted by the autocollimator (113) can be made incident on the reference reflector (1072), and the position of the returned calibration mark is recorded. By adjusting the inclination of the reference reflector (1072), the position of the calibration mark is made to coincide with the previously recorded position, that is, the position of the returned calibration mark remains unchanged, indicating that the inclination of the reference reflector (1072) has reached the first inclination, thereby ensuring that the inclination of the reference reflector (1072) has been confirmed to be accurate.

[0109] In this way, by introducing the autocollimator (113) to record the first inclination of the auxiliary reflector (1071), when the reflector is replaced, the inclination of the replaced reference reflector (1072) can obtain the first inclination, thereby improving the assembly accuracy of the reference reflector (1072).

[0110] In a possible implementation, the second axial distance of the reference objective lens (106) can also be adjusted. That is, when the light with the calibration mark emitted by the autocollimator (113) passes through the first lens (102), the beam splitter (103) and the reference objective lens (106) and is incident on the auxiliary reflector (1071), the second axial distance of the reference objective lens (106) is adjusted based on the focus clarity of the calibration mark detected by the detector (111).

[0111] Specifically, the second axial distance can be understood as the distance of the reference objective lens (106) in the direction of light propagation, that is, the distance in the direction of the optical axis. Fig.10As shown, it is another optical path schematic diagram of adjusting the reference objective lens provided in an embodiment of the present application. The light source (101) can be replaced by an autocollimator (113). The light with the calibration mark is incident on the auxiliary reflector (1071), and enters the detector (111) after being reflected. The calibration mark can be recorded in the detector (111). The focus clarity of the calibration mark can be changed by adjusting the second axial distance of the reference objective lens (106). When the focus clarity reaches the preset requirement, it indicates that the position of the reference objective lens has been adjusted. At this time, the auxiliary reflector (1071) is located on the focal plane of the reference objective lens (106), thereby realizing the adjustment of the axial position of the reference objective lens (106). It can be understood that at this time, the distance between the reference objective lens (106) and the beam splitter (103) is equal to the distance between the measuring objective lens (104) and the beam splitter (103). Among them, the adjustment of the second axial distance can be performed before the second inclination and the first eccentric distance.

[0112] In a possible implementation, the auxiliary reflector (1071) is replaced by a reference reflector (1072), which can be specifically: the auxiliary reflector (1071) is replaced by the reference reflector (1072); based on the focal plane position of the reference objective lens (106), the second axial distance of the reference reflector (1072) is adjusted with a third adjustment step; based on the Linnik interference fringes detected by the detector (111), the second axial distance is adjusted with a fourth adjustment step so that the second axial distance is equal to the first axial distance, and the fourth adjustment step is smaller than the third adjustment step.

[0113] Specifically, the second axial distance can be understood as the distance of the reference reflector (1072) in the direction of light propagation, that is, the distance in the direction of the optical axis. In order to adjust the axial distance of the reference reflector (1072) more quickly, the reference reflector (1072) can be roughly adjusted based on the focal plane position of the reference objective lens (106), that is, the reference objective lens (106) is adjusted according to the third adjustment step length. The third adjustment step length can be understood as the moving distance of the reference objective lens (106) in the axial direction. As an example, the moving distance at this time can be larger, so as to quickly determine the approximate position of the reference reflector (1072) in the axial direction. As an example, it can be adjusted until the distance between the reference reflector (1072) and the reference objective lens (106) is the focal length. Furthermore, due to the Linnick interference between the measuring beam and the reference beam, the Linnick interference fringes are detected in the detector (111), and the second axial distance is finely adjusted, that is, adjusted according to the fourth adjustment step. The fourth adjustment step can also be understood as the moving distance of the reference objective lens (106) in the axial direction. It is worth noting that the fourth adjustment step is smaller than the third adjustment step. As an example, the fourth adjustment step can take a smaller value, that is, the moving distance during fine adjustment can be smaller, so that there is only one bright fringe or only one dark fringe in the detector (111), indicating that the second axial distance is equal to the first axial distance at this time, and the position of the reference reflector (1072) completely overlaps with the original auxiliary reflector (1071). In this way, through the two adjustments of coarse adjustment and fine adjustment, the assembly efficiency can be improved, so that the reference reflector (1072) is located at a suitable axial position.

[0114] Based on the above wafer detection method, the present application embodiment also provides a wafer detection system, referring to Fig.11 As shown, it is a schematic diagram of a wafer detection system provided in an embodiment of the present application. The wafer detection system may include a light source (101), a first lens (102), a beam splitter (103), a measuring objective lens (104), a wafer to be measured (105), a reference objective lens (106), an auxiliary reflector (1071), a reference reflector (1072), a second lens (108), a third lens (110) and a detector (111).

[0115] The beam splitter (103) is used to split light emitted by the light source (101) into a measurement light beam propagating in a measurement light path where a measurement objective lens (104) is located, and a reference light beam propagating in a reference light path where a reference objective lens (106) is located. The first lens (102) is arranged on the light path between the light source (101) and the beam splitter (103), and the second lens (108) and the third lens (110) are both arranged on the light path between the beam splitter (103) and the detector (111).

[0116] The auxiliary reflector (1071) is arranged on the light exit side of the reference objective lens (106) and is used to reflect the reference light beam so as to form interference fringes. The wafer to be measured (105) is arranged on the light exit side of the measurement objective lens (104) and is used to reflect the measurement light beam so as to form interference fringes.

[0117] The detector (111) is used to detect interference fringes formed by the reflected measurement light beam and the reflected reference light beam after passing through the beam splitter (103); the reference reflector (1072) and the reference objective lens (106) are fixed on the same mechanical part and are used to replace the auxiliary reflector (1071) after the detector (111) detects the interference fringes, so as to detect the wafer (105) to be tested.

[0118] In one possible implementation, the wafer inspection system may further include an autocollimator (113), which is used to emit light with a calibration mark to the auxiliary reflector (1071) after forming interference fringes, and record the position of the returned calibration mark so that after the auxiliary reflector (1071) is replaced by a reference reflector (1072), the position of the returned calibration mark remains unchanged.

[0119] In a possible implementation, the light source (101) may include a single-mode laser light source (1012) and a white light source (1011); the single-mode laser light source (1012) is used to adjust the first axial distance of the auxiliary reflector (1071) with a first adjustment step size through Michelson interference fringes when emitting laser light; and the white light source (1011) is used to adjust the first axial distance of the auxiliary reflector (1071) with a second adjustment step size through Michelson interference fringes when emitting white light; the second adjustment step size is smaller than the first adjustment step size.

[0120] In a possible implementation, the wafer inspection system may further include an auxiliary beam splitter (109) and an auxiliary detector (112), referring to Fig.12 As shown, it is a schematic diagram of another wafer inspection system provided in an embodiment of the present application.

[0121] The auxiliary beam splitter (109) is arranged between the second lens (108) and the third lens (110), and the auxiliary detector (112) is used to image the light passing through the auxiliary beam splitter (109). In other words, the auxiliary detector (112) can also be used to detect the interference fringes, not relying on only one detector (111), thereby improving assembly efficiency.

[0122] An embodiment of the present application provides a wafer detection system, which includes a light source, a beam splitter, a measuring objective lens, a reference objective lens, a detector, an auxiliary reflector, a wafer to be measured and a reference reflector, wherein the beam splitter is used to split the light emitted by the light source into a measuring beam propagating in a measuring optical path where the measuring objective lens is located, and a reference beam propagating in a reference optical path where the reference objective lens is located; the auxiliary reflector is arranged on the light output side of the reference objective lens, and is used to reflect the reference beam; the wafer to be measured is arranged on the light output side of the measuring objective lens, and is used to reflect the measuring beam; the detector is used to detect interference fringes formed by the reflected measuring beam and the reflected reference beam after passing through the beam splitter; the reference reflector and the reference objective lens are fixed on the same mechanical part, and is used to replace the auxiliary reflector after the detector detects the interference fringes, so as to detect the wafer to be measured. In short, by introducing an additional independent reflector, namely the auxiliary reflector, the auxiliary reflector has a higher degree of freedom in adjustment and will not be disturbed by the reference objective lens. It can determine its own axial position (namely the first axial distance) and degree of inclination (namely the first inclination). In addition, it can also help adjust the posture of the reference objective lens in the future, that is, determine the second inclination and the first eccentric distance. In this way, after the auxiliary reflector has been able to help adjust the interference fringes, it can be replaced by the reference reflector, thereby realizing the decoupling of the adjustment dimensions of the reference objective lens and the reference reflector, and improving the adjustment efficiency and accuracy.

[0123] A person skilled in the art can understand that all or part of the steps of implementing the above method embodiment can be completed by program instruction hardware, and the above program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above method embodiment; and the above storage medium can be at least one of the following media: read-only memory (English: Read-only Memory, abbreviated: ROM), RAM, magnetic disk or optical disk, etc. Various media that can store program codes.

[0124] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0125] The above is only a preferred implementation of the present application. Although the present application has been disclosed as a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present application without departing from the scope of the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.

Claims

1. A wafer detection method, characterized in that: The method comprises: When the light source (101), the first lens (102), the beam splitter (103), the wafer to be tested (105), the second lens (108) and the detector (111) are configured to be located in an optical path, a first light spot position detected by the detector (111) is obtained; and when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the second lens (108) and the detector (111) are configured to be located in an optical path, a second light spot position detected by the detector (111) is obtained; Based on the first light spot position and the second light spot position, adjusting a first inclination of the auxiliary reflector (1071) so that the first light spot position and the second light spot position coincide with each other; When the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be tested (105), the second lens (108) and the detector (111) are arranged in an optical path, adjusting a first axial distance of the auxiliary reflector (1071) by means of Michelson interference fringes detected by the detector (111); When the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be measured (105), the second lens (108), the detector (111), the reference objective lens (106), the measuring objective lens (104) and the third lens (110) are arranged in an optical path, a second inclination and a first eccentricity of the reference objective lens (106) are adjusted by detecting Linnik interference fringes; The auxiliary reflector (1071) is replaced by a reference reflector (1072), and the reference reflector (1072) and the reference objective lens (106) are fixed on the same mechanical part.

2. The wafer detection method according to claim 1, characterized in that: The step of replacing the auxiliary reflector (1071) with a reference reflector (1072) comprises: After adjusting the first inclination of the auxiliary reflector (1071), emitting light with a calibration mark to the auxiliary reflector (1071) through an autocollimator (113), and recording the position of the returned calibration mark; Based on the position of the returned calibration mark, the auxiliary reflector (1071) is replaced with the reference reflector (1072) so that the position of the returned calibration mark remains unchanged.

3. The wafer detection method according to claim 1, characterized in that: When the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be tested (105), the second lens (108), and the detector (111) are arranged in an optical path, adjusting a first axial distance of the auxiliary reflector (1071) by using Michelson interference fringes detected by the detector (111), comprising: When a single-mode laser light source (1012), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be tested (105), the second lens (108) and the detector (111) are arranged in an optical path, a first axial distance of the auxiliary reflector (1071) is adjusted with a first adjustment step length based on Michelson interference fringes detected by the detector (111); The single-mode laser light source (1012) is replaced with a white light source (1011), and the first axial distance of the auxiliary reflector (1071) is adjusted with a second adjustment step length based on the Michelson interference fringes detected by the detector (111); the second adjustment step length is smaller than the first adjustment step length.

4. The wafer detection method according to claim 1, characterized in that: The method comprises: adjusting the second inclination and the first eccentricity of the reference objective lens (106) by detecting Linnik interference fringes when the light source (101), the first lens (102), the beam splitter (103), the auxiliary reflector (1071), the wafer to be measured (105), the second lens (108), the detector (111), the reference objective lens (106), the measuring objective lens (104) and the third lens (110) are arranged in an optical path. When the surface light source (114), the measuring objective lens (104), the beam splitter (103), the second lens (108), the third lens (110), and the detector (111) are arranged in an optical path, obtaining a first entrance pupil position detected by the detector (111), wherein the measuring objective lens (104) is located on the optical path between the surface light source (114) and the beam splitter (103), and the third lens (110) is located on the optical path between the beam splitter (103) and the detector (111); When the surface light source (114), the reference objective lens (106), the beam splitter (103), the second lens (108), the third lens (110), and the detector (111) are arranged in an optical path, obtaining a second entrance pupil position detected by the detector (111), wherein the reference objective lens (106) is located in the optical path between the surface light source (114) and the beam splitter (103); Based on the first entrance pupil position and the second entrance pupil position, adjusting the first eccentric distance of the reference objective lens (106) so that the first entrance pupil position and the second entrance pupil position coincide with each other; When the light source (101), the first lens (102), the beam splitter (103), the reference objective lens (106), the auxiliary reflector (1071), the measuring objective lens (104), the wafer to be measured (105), the second lens (108), the third lens (110) and the detector (111) are arranged in an optical path, the second inclination and the first eccentricity of the reference objective lens (106) are adjusted by detecting Linnik interference fringes.

5. The wafer detection method according to claim 4, characterized in that: The method further comprises: When the light with the calibration mark emitted by the autocollimator (113) passes through the first lens (102), the beam splitter (103) and the reference objective lens (106) and is incident on the auxiliary reflector (1071), the second axial distance of the reference objective lens (106) is adjusted according to the focus clarity of the calibration mark detected by the detector (111).

6. The wafer detection method according to any one of claims 1 to 5, characterized in that: The step of replacing the auxiliary reflector (1071) with the reference reflector (1072) comprises: The auxiliary reflector (1071) is replaced by the reference reflector (1072), and the second axial distance of the reference reflector (1072) is adjusted with a third adjustment step length based on the focal plane position of the reference objective lens (106); Based on the Linnik interference fringes detected by the detector (111), the second axial distance is adjusted with a fourth adjustment step length so that the second axial distance is equal to the first axial distance; the fourth adjustment step length is smaller than the third adjustment step length.

7. A wafer inspection system, characterized in that: The system comprises: A light source (101), a beam splitter (103), a measuring objective lens (104), a reference objective lens (106), and a detector (111); the beam splitter (103) is used to split the light emitted by the light source (101) into a measuring light beam propagating in a measuring light path where the measuring objective lens (104) is located, and a reference light beam propagating in a reference light path where the reference objective lens (106) is located; A first lens (102) is arranged on the optical path between the light source (101) and the beam splitter (103); A second lens (108) and a third lens (110) are both arranged on the optical path between the beam splitter (103) and the detector (111); An auxiliary reflector (1071), arranged on the light-emitting side of the reference objective lens (106), and used for reflecting the reference light beam; A wafer to be measured (105), arranged on the light-emitting side of the measuring objective lens (104), and used for reflecting the measuring light beam; The detector (111) is used to detect interference fringes formed after the reflected measurement beam and the reflected reference beam pass through the beam splitter (103); A reference reflector (1072), the reference reflector (1072) and the reference objective lens (106) being fixed on the same mechanical part, and being used to replace the auxiliary reflector (1071) after the detector (111) detects the interference fringes, so as to detect the wafer (105) to be tested.

8. The wafer inspection system according to claim 7, characterized in that: The system also includes an autocollimator (113); The autocollimator (113) is used to emit light with a calibration mark to the auxiliary reflector (1071) after the interference fringes are formed, and to record the position of the returned calibration mark, so that after the auxiliary reflector (1071) is replaced by the reference reflector (1072), the position of the returned calibration mark remains unchanged.

9. The wafer inspection system according to claim 7, characterized in that: The light source (101) comprises a single-mode laser light source (1012) and a white light source (1011); The single-mode laser light source (1012) is used to adjust the first axial distance of the auxiliary reflector (1071) with a first adjustment step length through Michelson interference fringes when emitting laser light; The white light source (1011) is used to adjust the first axial distance of the auxiliary reflector (1071) with a second adjustment step length through Michelson interference fringes when emitting white light; the second adjustment step length is smaller than the first adjustment step length.

10. The wafer inspection system according to any one of claims 7 to 9, characterized in that: The system further comprises: an auxiliary beam splitter (109), arranged between the second lens (108) and the third lens (110); An auxiliary detector (112) is used to image the light passing through the auxiliary beam splitter (109).

Images