Semiconductor detection device and control method thereof

Abstract

According to the semiconductor detection device and the control method thereof, the objective lenses with multiple multiplying powers are arranged, the objective lenses can be flexibly switched according to the requirement of detection precision, and switching between high detection precision and low detection speed and low detection precision and high detection speed is achieved; and the distribution of the dark field illumination light spots is regulated and controlled by moving the position of the dark field slit, so that the dark field illumination light spots are matched with the dark field acquisition view field under any objective lens magnification, and crosstalk between the dark field acquisition view field and the dark field acquisition view field can be avoided by controlling the dark field illumination light spot area.

Description

Technical Field

[0001] The present application relates to the field of semiconductor detection technology, and in particular to a semiconductor detection device and a control method thereof. Background Art

[0002] In the field of semiconductor inspection, bright field inspection is an important inspection method in optical inspection. However, bright field inspection is limited by the diffraction limit, and the minimum inspection defect is only the radius of the Airy disk; while dark field inspection is based on Rayleigh scattering or Mie scattering of small-sized particles. As long as the scattering signal of small-sized defects can be detected, the detection sensitivity can be improved. Therefore, in order to improve the detection sensitivity of the detection device, a dark field detection device is usually configured in the bright field detection device to construct a bright and dark field detection device.

[0003] The intensity of the bright field signal light is much greater than that of the dark field signal light. The bright field signal light has a great interference with the dark field signal light, which reduces the dark field detection accuracy. In order to solve the above problems, some solutions perform bright field and dark field detection on the sample under test respectively, and then perform data fusion. This method takes a long time. At the same time, vibration during the detection process will cause errors in the alignment of the two detections, reducing the detection accuracy. There are also some solutions that use different wavelengths of illumination light sources for bright and dark fields to distinguish between bright and dark field signal lights. The wafer under test responds differently to different illumination wavelengths, and the band-dividing solution limits the detection band. Summary of the invention

[0004] In view of this, the present invention provides a semiconductor detection device and a control method to improve the detection accuracy of semiconductor wafers in bright and dark fields.

[0005] In order to solve the technical problem that the wafer detection accuracy in the existing solution needs to be improved, this application adopts the following technical solution: One of the purposes of the present application is to provide a semiconductor wafer bright and dark field defect detection device, comprising a first illumination light source, an objective lens, a second illumination light source, a dark field slit, a bright field detector and a dark field detector, wherein the magnification of the objective lens is switchable, and the position of the dark field slit is movable; The light beam emitted by the first illumination light source is irradiated onto the surface of the wafer to be measured through the objective lens, and the bright field signal light generated by the reflection passes through one side of the optical axis of the objective lens to form a bright field acquisition field which is acquired by the bright field detector, and a bright field image is obtained by imaging; The light beam emitted by the second illumination light source is irradiated to the surface of the wafer under test through the dark field slit, and the dark field acquisition field formed by the scattered dark field signal light passing through the other side of the optical axis of the objective lens is acquired by the dark field detector, and a dark field image is obtained by imaging; wherein: The distribution of the dark field illumination spot on the surface of the wafer under test is regulated by moving the position of the dark field slit, so that the dark field illumination spot covers the dark field acquisition field corresponding to the objective lens at any magnification and avoids crosstalk with the bright field acquisition field.

[0006] The bright field image and the dark field image are collected simultaneously and used to obtain the bright field defect characteristics and the dark field defect characteristics of the surface of the wafer under test respectively through image processing.

[0007] In some embodiments, the light beam emitted by the second illumination light source is imaged on the surface of the wafer under test via a dark field illumination light path, and the dark field illumination light path includes the dark field slit, and a first lens assembly and a second lens assembly arranged in sequence, and the first lens assembly and the second lens assembly are used to directly converge the light beam passing through the dark field slit and project it onto the surface of the wafer under test.

[0008] In some embodiments, there are two second illumination light sources, the dark field illumination light path through which the light beam emitted by the second illumination light source passes is symmetrically distributed, and the incident plane of the light beam emitted by the second illumination light source that is incident on the surface of the wafer to be measured after passing through the dark field illumination light path is not perpendicular to the plane where the dark field illumination spot is located.

[0009] In some embodiments, there is one second illumination light source, and the incident plane of the light beam emitted by the second illumination light source and incident on the surface of the wafer under test after passing through the dark field illumination light path is inclined to the plane where the dark field illumination spot is located.

[0010] In some of the embodiments, a spectroscopic element having two reflective surfaces is further included. The bright field signal light and the dark field signal light generated on the surface of the wafer to be measured are respectively incident on the two reflective surfaces of the spectroscopic element through a common imaging optical path. The two reflective surfaces of the spectroscopic element reflect the bright field signal light and the dark field signal light to the bright field detector and the dark field detector respectively.

[0011] In some embodiments, the bright field detector and the dark field detector are respectively a bright field camera and a dark field camera, the imaging planes of each of the bright field camera and the dark field camera are conjugate with the plane where the wafer to be measured is located, and the field of view center of the bright field camera and the field of view center of the dark field camera are symmetrically distributed about the optical center field of view.

[0012] In some embodiments, the off-axis amount L of the dark field camera, the magnification M of the objective lens, and the distance l of the dark field illumination spot relative to the optical center field of view are related as follows: l=L / M.

[0013] In some embodiments, in the dark field illumination light path, the dark field slit is moved on a plane perpendicular to the optical axis to adapt to the magnification of the objective lens; when the magnification of the objective lens is M1, the position of the dark field illumination spot must satisfy l1, and the dark field slit is moved to l′1, and l′ 1= l1 / M D =L / M1 / M D , the M D is the magnification of the dark field illumination light path. In some embodiments, if the target length of the dark field camera is K, the maximum imaging field of view is the field length of the objective lens at the minimum magnification K′=K / Mmin, the length of the dark field illumination spot must satisfy C=K′+b, b is the range of the dark field illumination spot larger than the field of view required for imaging, b is 1~5mm, and the slit length of the dark field slit is configured as C′=C / M D .

[0014] In some embodiments, the light emitting surface of the second illumination light source is larger than the moving range of the dark field slit.

[0015] In some of the embodiments, a driving device electrically connected to the dark field slit is further included, wherein the driving device is used to drive the dark field slit to move, and the driving device includes a stepping motor, a servo motor or a piezoelectric driver.

[0016] The second object of the present application is to provide a control method, comprising the following steps: Switching the magnification of the objective lens; Acquiring a target position of the dark field slit; The dark field slit is moved on a plane perpendicular to the optical axis of the dark field illumination light path, so that the dark field illumination spot covers the dark field acquisition field corresponding to the current magnification of the objective lens and avoids crosstalk with the bright field acquisition field.

[0017] In some embodiments, in the dark field illumination light path, the dark field slit is moved on a plane perpendicular to the optical axis to adapt to the magnification of the objective lens; when the magnification of the objective lens is M1, the position of the dark field illumination spot must satisfy l1, and the dark field slit is moved to l′1, and l′ 1= l1 / M D =L / M1 / M D , the M D is the magnification of the dark field illumination light path, and L is the eccentricity of the dark field detector relative to the optical center field of view.

[0018] In some embodiments, if the target length of the dark field detector is K, the maximum imaging field of view is the field length K′=K / Mmin of the objective lens at the minimum magnification, the length of the dark field illumination spot must satisfy C=K′+b, b is the range of the dark field illumination spot larger than the field of view required for imaging, b is 1-5 mm, and the slit length of the dark field slit is configured as C′=C / M D .

[0019] This application adopts the above technical solution, and its beneficial effects are as follows: The semiconductor detection device and control method provided by the present application adjust the distribution of the dark field illumination spot in the dark field view by moving the position of the dark field slit, so that the dark field illumination spot covers the dark field view corresponding to the objective lens at all magnifications, thereby solving the problem that the dark field view corresponding to the dark field detector changes when the objective lens is switched; at the same time, the scheme achieves better bright field imaging and dark field imaging effects by accurately adjusting the dark field illumination spot area to avoid crosstalk with the bright field view, which is beneficial to improving detection accuracy, and can also cover the dark field imaging field of view at different optical magnifications, with good comprehensive performance.

[0020] The semiconductor detection device and control method provided in the present application can realize simultaneous detection of bright and dark fields with a common optical path and divided fields of view, and can support switching of objective lenses at different magnifications to synchronously change the imaging magnification, thereby realizing switching between high detection accuracy and low detection speed and low detection accuracy and high detection speed, thereby better meeting different application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only 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.

[0022] Figure 1 A schematic diagram of the structure of a semiconductor wafer bright and dark field defect detection device provided in Example 1 of the present application; Figure 2 A schematic diagram of a specific optical path provided in Example 1 of the present application; Figure 3 A schematic diagram of the installation position of the camera target surface on the image side provided in Example 1 of the present application; Figure 4 This is a schematic diagram of the common light path field distribution of bright and dark fields provided in Example 1 of the present application; Figure 5 This is a step flow chart of the control method of the semiconductor detection device provided in Example 2 of the present application. DETAILED DESCRIPTION

[0023] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application. In the description of the present application, it should be understood that the terms "upper", "lower", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined. In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0024] Example 1 See also Figure 1 , is a schematic diagram of the structure of the semiconductor wafer bright and dark field defect detection device provided in Example 1 of the present application, including a first illumination light source 100, an objective lens 200, a second illumination light source 300, a bright field detector 400, a dark field detector 500 and a dark field slit 600, the magnification of the objective lens 200 can be switched, and the position of the dark field slit 600 can be moved. The technical solution implemented is described in detail below.

[0025] The first illumination light source 100 is used to emit a bright field illumination light beam. The specific structure of the first illumination light source 100 is not limited, and it can be a single light source or multiple light sources. The light beam emitted by the first illumination light source 100 is split or combined to meet the light path requirements to ensure the flexibility of the entire system.

[0026] The objective lens 200 can be set to a plurality of objective lenses with switchable magnifications. In practice, these objective lenses can be flexibly switched according to the requirements of detection accuracy. After the objective lens is switched, the dark field field of view corresponding to the dark field detector will also change due to the change of the microscopic magnification of the imaging system.

[0027] In some embodiments, the objective lens 200 may be configured to include a plurality of objective lens combinations with different magnifications, such as Figure 1The combination of objective lenses 1, ... and objective lenses n shown in the figure can switch objective lenses of corresponding magnifications into the optical path according to the actual requirements of detection accuracy.

[0028] In some embodiments, the objective lens 200 may also be configured to include a single objective lens and an objective lens converter. The objective lens converter may switch the objective lens to different magnifications, and the objective lens of the corresponding magnification may be switched into the optical path according to actual detection accuracy requirements.

[0029] The second illumination light source 300 is used to emit a dark field illumination light beam. The specific structure of the second illumination light source 300 is not limited, and can be a single light source or multiple light sources. The light beam emitted by the second illumination light source 300 is split or combined to meet the light path requirements to ensure the flexibility of the entire system.

[0030] In this embodiment, the second illumination light source 300 can be set according to actual needs. For example, the light beam of the second illumination light source 300 can be shaped according to needs; or the light beam position of the second illumination light source 300 can be adjusted to meet detection needs.

[0031] The bright field detector 400 and the dark field detector 500 are used to obtain the imaging signal of the first illumination light source and the imaging signal of the second illumination light source respectively.

[0032] In some embodiments, the bright field detector 400 and the dark field detector 500 are a bright field camera and a dark field camera, respectively.

[0033] The dark field slit 600 is used to modulate the light beam in the dark field illumination light path, and the position of the dark field illumination light spot is dynamically adjusted by moving the slit, so that it can always coincide with the dark field imaging field of view. The dark field slit 600 can be a rectangular aperture.

[0034] The working method of the semiconductor wafer bright and dark field defect detection device provided in the above embodiment of the present application is as follows: The light beam emitted by the first illumination light source 100 is irradiated to the surface of the wafer to be measured through the objective lens 200, and the bright field signal light generated by the reflection passes through one side of the optical axis of the objective lens 200 to form a bright field acquisition field which is acquired by the bright field detector 400, and a bright field image is obtained by imaging; The light beam emitted by the second illumination light source 300 is irradiated to the surface of the wafer under test through the dark field slit 600, and the dark field signal light generated by scattering passes through the other side of the optical axis of the objective lens 200 to form a dark field acquisition field of view which is acquired by the dark field detector 500, and a dark field image is obtained by imaging; The distribution of the dark field illumination spot on the surface of the wafer to be measured is regulated by moving the position of the dark field slit 600, so that the dark field illumination spot covers the dark field acquisition field corresponding to the objective lens 300 at any magnification and avoids crosstalk with the bright field acquisition field; The bright field image and the dark field image are collected simultaneously and used to obtain the bright field defect characteristics and the dark field defect characteristics of the surface of the wafer under test respectively through image processing.

[0035] The semiconductor detection device provided in the present embodiment is provided with objective lenses with multiple magnifications, and these objective lenses can be flexibly switched according to the requirements of detection accuracy. After the objective lens is switched, the dark field field of view corresponding to the dark field detector will also change due to the change in the microscope magnification of the imaging system, which may cause some unexpected situations. For example, the dark field illumination spot is too small to cover the entire dark field imaging field of view, and the dark field illumination spot is too large to interfere with the bright field imaging. The present application performs beam modulation on the light beam emitted by the second illumination light source by moving the position of the dark field slit to regulate the distribution of the dark field illumination spot in the dark field of view, so that the dark field illumination spot covers the dark field of view corresponding to the dark field detector under the required multiple objective lenses, and at the same time controls the dark field illumination spot area to avoid crosstalk with the bright field signal.

[0036] In some embodiments, the light beam emitted by the second illumination light source is imaged on the surface of the wafer under test through a dark field illumination optical path, and the dark field illumination optical path includes a dark field slit 600, and a first lens assembly 710 and a second lens assembly 720 arranged in sequence. The light beam emitted by the second illumination light source is imaged on the surface of the wafer under test in a critical illumination manner after passing through the dark field slit 600, and then through the first lens assembly 710 and the second lens assembly 720. Of course, in some cases, the light source beam can also be used to illuminate the surface of the wafer under test in a Kohler illumination manner by changing the lens group structure of the dark field illumination optical path.

[0037] See also Figure 2 , which is a schematic diagram of a specific optical path provided in Example 1 of the present application, including: a first illumination light source 100, a reflector 10, a beam splitter 20, a dichroic mirror 30, an imaging lens group 40, a focus detection assembly 50, an objective lens 200, a second illumination light source 300, a bright field detector 400, a dark field detector 500 and a beam splitter element 800. The specific optical path is as follows: The light beam emitted by the first illumination light source 100 is sequentially irradiated to the surface of the wafer under test through the reflector 10, the beam splitter 20, the dichroic mirror 30 and the objective lens 200. The bright field signal light generated by the reflection passes through the objective lens 200, the dichroic mirror 30 and the imaging lens group 40, and then the bright field field formed by the beam splitter element 800 is acquired by the bright field detector 400, and a bright field image is obtained by imaging.

[0038] The light beam emitted by the second illumination light source 300 passes through the dark field slit 600 and then through the dark field illumination lens (composed of a first lens assembly 710 and a second lens assembly 720) to irradiate the surface of the wafer to be measured. The dark field signal light generated by scattering passes through the objective lens 200 and then through the dichroic mirror 30 and the imaging lens assembly 40, and then through the dark field field formed by the spectroscopic element 800 is acquired by the dark field detector 500, and a dark field image is obtained by imaging.

[0039] In this embodiment, the spectroscopic element 800 is a spectroscopic prism or a multi-faceted reflector. The spectroscopic prism can be a right-angle isosceles prism, and the multi-faceted reflector can be an isosceles trapezoidal structure with two reflecting surfaces. The bright field detector 400 and the dark field detector 500 are a bright field camera and a dark field camera, respectively.

[0040] It can be understood that the bright field signal light and dark field signal light generated by the main optical path provided in the above-mentioned embodiments of the present application on the surface of the wafer under test are respectively incident on the two reflecting surfaces of the spectroscopic element 800 through the common imaging optical path, and the two reflecting surfaces of the spectroscopic element 800 reflect the bright field signal light and the dark field signal light to the bright field detector 400 and the dark field detector 500 respectively.

[0041] Furthermore, the center of the beam splitter element 800 can coincide with the optical axis, and the two relatively narrow fields of view outside the optical axis are reflected to the target surfaces of the bright field camera and the dark field camera respectively. Both the bright field camera and the dark field camera use line scan cameras, and the scanning dimension field of the line scan camera is very small. Therefore, the two narrow fields of view distributed by the beam splitter element provided in this application meet the field width of the scanning dimension, and do not split in the direction perpendicular to the schematic diagram, so as to meet all the field of view requirements in the length direction of the target surface of the line scan camera.

[0042] See also Figure 3 , is a schematic diagram of the installation position of the camera target surface on the image side provided in this embodiment 1.

[0043] In this embodiment, the imaging planes of the bright field camera and the dark field camera are conjugate with the plane of the wafer to be measured, the field of view center of the bright field camera and the field of view center of the dark field camera are symmetrically distributed with respect to the optical center field of view, and the distance from the optical center field of view is L, and the conjugate positions of the bright field field of view and the dark field field of view on the wafer are related to the magnification of the optical system.

[0044] It can be understood that the present application changes the system magnification by switching the objective lens magnification (such as 1X to 20X, etc.), that is, when switching to other magnification objective lenses, the bright field field and dark field field acquisition positions will be changed from solid lines (such as Figure 1 If there are multiple magnifications, there will be multiple acquisition positions for the bright field and dark field, such as Figure 4 As shown, the common imaging optical path through which the bright field signal light and the dark field signal light pass is the lowest magnification M min In this case, the distance between the bright field acquisition field and the dark field acquisition field and the central field of view is L1=L / M. min ; The common imaging optical path through which the bright field signal light and the dark field signal light pass is the maximum magnification M max In this case, the distance between the bright field and dark field and the central field is L2=L / M. max The length of the camera target surface K corresponds to the maximum length on the object side K′=K / Mmin .

[0045] Please refer to Figure 4 In the optical imaging field of view, since the bright field camera and the dark field camera are symmetrically distributed around the central field of view (optical axis), the specific positions of the bright field and the dark field are different at different magnifications. For the prior art, since the camera is at the center of the field of view, this problem does not exist, so the dark field illumination is usually a very narrow line spot, and there is no need to consider covering multiple fields of view, and there is no need to consider the uniformity in the scanning direction; the dark field field of view provided by the present application needs to be based on the requirements of the optical system for simultaneous detection of bright and dark fields. The dark field illumination spot follows the different magnifications and has a precise position, always keeping the illumination spot completely overlapped with the dark field field of view.

[0046] Specifically, when the objective lens 200 switches the magnification, the dark field illumination light is displaced following the objective lens magnification switching. The theoretical displacement is determined according to the eccentricity L of the dark field camera setting (i.e., the distance L between the bright field camera and the dark field camera from the optical center field of view) and the objective lens magnification M, where l=L / M, and l is the position of the dark field illumination spot relative to the center field of view.

[0047] Furthermore, in this embodiment, the position of the dark field slit is moved to control the position of the dark field illumination spot (eg Figure 1 As shown). In the dark field illumination light path, the dark field slit is moved on a plane perpendicular to the optical axis to adapt to the magnification of the objective lens. When the imaging magnification of the objective lens is M1, the position of the dark field illumination spot must satisfy l1, and the dark field slit is moved to l′1, and l′ 1= l1 / M D =L / M1 / M D , M D is the magnification of the dark field illumination light path. According to this method, the positions of the dark field slit 600 at other imaging magnifications are calibrated respectively: l′1, l′2, ... l′ n It can be understood that when the imaging magnification is M1 after switching the objective lens, the dark field slit of the modulated light beam in the dark field illumination optical path should be moved to l′1; when the imaging magnification is M2 after switching the objective lens, the dark field slit of the modulated light beam in the dark field illumination optical path should be moved to l′2, and so on.

[0048] It can be understood that by moving the dark field slit 600 to dynamically adjust the position of the dark field illumination spot, it can always coincide with the dark field imaging field of view to ensure that the dark field illumination spot covers the dark field of view corresponding to the dark field detectors under the required multiple objective lenses, while controlling the dark field illumination spot area to avoid crosstalk with the bright field signal.

[0049] It should be noted that: in practice, for the convenience of operation, when moving the position of the dark field illumination spot and the dark field slit, the edge of the dark field illumination spot and the edge of the dark field slit are used as reference objects, that is, the position of the dark field illumination spot and the dark field slit is moved by moving the edge of the dark field illumination spot and the edge of the dark field slit.

[0050] It should be noted that the light emitting surface of the second illumination light source 300 should be larger than the moving range of the slit to ensure that sufficient light can pass through the slit at each position.

[0051] Furthermore, the length of the dark field illumination spot does not need to follow the change in imaging magnification, as long as the maximum field of view can be covered. If the target length of the dark field camera is K, the maximum extent of the corresponding imaging field of view, that is, the maximum imaging field of view is the field length of the objective lens 200 at the minimum magnification, which must satisfy K′=K / Mmin. The length of the dark field illumination spot is C=K′+b, where b is the range in which the dark field illumination spot is larger than the field of view required for imaging. Usually, in order to reduce engineering difficulty, some redundancy is eliminated. In this embodiment, b=1~5mm is preferred. The slit length of the dark field slit is configured as C′=C / M D .

[0052] In this embodiment, the dark field slit 600 is also electrically connected to a driving device (not shown), which is composed of a high-precision stepper motor, a servo motor or a piezoelectric driver to drive the dark field slit 600 to move, thereby ensuring that the illumination spot coincides with the dark field view at each magnification.

[0053] In some embodiments, in order to ensure the uniformity of illumination, the dark field illumination scheme provided in this embodiment adopts external oblique incident illumination, that is, the incident plane of the light beams emitted by the two second illumination light sources 300 incident on the surface of the wafer to be measured is not perpendicular to the plane where the dark field illumination spot is located, that is, the two dark field illumination light paths are arranged on the same side of the optical center field of view, and are symmetrical with the vertical plane of the optical center field of view, and both emit illumination light beams to the surface of the wafer at a certain tilt angle, and the two illumination light beams overlap on the surface of the wafer and the overlapping area constitutes a dark field illumination spot. It can be understood that for the surface light source with better uniformity to be projected and imaged at the required illumination position on the surface of the wafer to be measured, the illumination device needs to reach the imaging level to ensure that the dark field illumination contour is clear; in addition, the dark field illumination light path adopts a critical illumination method, that is, the light beam emitted by the second illumination light source 300 is imaged on the surface of the wafer after passing through the illumination lens group. This illumination method can form a narrow and strong illumination feature on the surface of the wafer, and at this time, the uniform light source imaging is projected on the area corresponding to multiple magnifications of the dark field.

[0054] It should be noted that: since the incident plane is not perpendicular to the light spot, at this time, the optical path difference from the light source to different positions on the illumination light spot is different, and the stretching effect of the single-sided illumination oblique incidence causes the light spot to be uneven in length. In order to ensure good uniformity in the length direction, a symmetrical lighting design is adopted, that is, there are two second illumination light sources 300, and the optical path of the light beam emitted by the second illumination light source 300 is symmetrically distributed, and the incident plane of the light beam emitted by the second illumination light source incident on the surface of the wafer to be measured is not perpendicular to the plane where the dark field illumination spot is located.

[0055] In other embodiments, a single dark field illumination light source may be provided, in which a single dark field illumination light source is disposed on one side of the optical center field of view, and the incident plane of the light is non-perpendicular to the plane where the dark field illumination spot is located, that is, the incident plane of the light beam emitted by the dark field illumination light source is incident on the surface of the wafer to be measured through the dark field illumination light path and is inclined to the plane where the dark field illumination spot is located, and the dark field illumination light path is parallel to or coincides with the vertical plane of the optical center field of view. At this time, the optical path difference from the light source to each position on the illumination spot will be slightly different, but will have little effect on the illumination uniformity. It can be understood that at this time, the dark field illumination system adopts a single-sided critical illumination design.

[0056] The semiconductor detection device provided in the above-mentioned embodiment of the present application is provided with objective lenses of multiple magnifications, and these objective lenses can be flexibly switched according to the requirements of detection accuracy, so as to realize the switching between high detection accuracy and low detection speed and low detection accuracy and high detection speed; the distribution of the dark field illumination spot in the dark field of view is regulated by moving the position of the dark field slit, so that the dark field illumination spot covers the dark field of view corresponding to the dark field detector under the objective lens of any magnification, and at the same time controls the dark field illumination spot area to avoid crosstalk with the bright field signal.

[0057] Example 2 See also Figure 5 , which is a flow chart of the steps of the control method of the semiconductor detection device provided in Embodiment 2 of the present application, is applied to the semiconductor detection device provided in any of the above embodiments, and includes the following steps: Step S510: Switch the magnification of the objective lens.

[0058] Step S520: Acquire the target position of the dark field slit.

[0059] In this embodiment, the bright field detector and the dark field detector are respectively a bright field camera and a dark field camera, the imaging planes of the bright field camera and the dark field camera are conjugate with the plane where the wafer to be measured is located, the field of view center of the bright field camera and the field of view center of the dark field camera are symmetrically distributed with respect to the optical center field of view, the eccentricity L of the dark field camera, the magnification M of the objective lens and the distance l of the dark field illumination spot relative to the optical center field of view, the three have the following relationship l=L / M.

[0060] This application changes the system magnification by switching the objective lens magnification (such as 1X to 20X, etc.), that is, when switching to other magnification objective lenses, the bright field and dark field acquisition positions will be changed from solid lines (such as Figure 1 If there are multiple magnifications, there will be multiple acquisition positions for the bright field and dark field, such as Figure 4 As shown, the common imaging optical path through which the bright field signal light and the dark field signal light pass is the lowest magnification M min In this case, the distance between the bright field acquisition field and the dark field acquisition field and the central field of view is L1=L / M. min ; The common imaging optical path through which the bright field signal light and the dark field signal light pass is the maximum magnification M max In this case, the distance between the bright field and dark field and the central field is L2=L / M. max The length of the camera target surface K corresponds to the maximum length on the object side K′=K / M min .

[0061] Please refer to Figure 4 In the optical imaging field of view, since the bright field camera and the dark field camera are symmetrically distributed around the central field of view (optical axis), the specific positions of the bright field and the dark field are different at different magnifications. For the prior art, since the camera is at the center of the field of view, this problem does not exist, so the dark field illumination is usually a very narrow line spot, and there is no need to consider covering multiple fields of view, and there is no need to consider the uniformity in the scanning direction; the dark field field of view provided by the present application needs to be based on the requirements of the optical system for simultaneous detection of bright and dark fields. The dark field illumination spot follows the different magnifications and has a precise position, always keeping the illumination spot completely overlapped with the dark field field of view.

[0062] Specifically, when the objective lens 200 switches the magnification, the dark field illumination light is displaced following the objective lens magnification switching. The theoretical displacement is determined according to the eccentricity L of the dark field camera setting (i.e., the distance L between the bright field camera and the dark field camera from the optical center field of view) and the objective lens magnification M, where l=L / M, and l is the position of the dark field illumination spot relative to the center field of view.

[0063] Step S530: moving the dark field slit on a plane perpendicular to the optical axis of the dark field illumination light path, so that the dark field illumination spot covers the dark field acquisition field corresponding to the current magnification of the objective lens and avoids crosstalk with the bright field acquisition field.

[0064] In this embodiment, the position of the dark field illumination spot is controlled by moving the position of the dark field slit (as shown in FIG1 ). In the dark field illumination light path, the dark field slit is moved on a plane perpendicular to the optical axis to adapt to the magnification of the objective lens. When the imaging magnification of the objective lens is M1, the position of the dark field illumination spot must satisfy l1, and the dark field slit is moved to l′1, and l′ 1= l1 / M D =L / M1 / MD , M D is the magnification of the dark field illumination light path. According to this method, the positions of the dark field slit 600 at other imaging magnifications are calibrated respectively: l′1, l′2, ... l′ n It can be understood that when the imaging magnification is M1 after switching the objective lens, the dark field slit of the modulated light beam in the dark field illumination optical path should be moved to l′1; when the imaging magnification is M2 after switching the objective lens, the dark field slit of the modulated light beam in the dark field illumination optical path should be moved to l′2, and so on.

[0065] It can be understood that by moving the dark field slit 600 to dynamically adjust the position of the dark field illumination spot, it can always coincide with the dark field imaging field of view to ensure that the dark field illumination spot covers the dark field of view corresponding to the dark field detectors under the required multiple objective lenses, while controlling the dark field illumination spot area to avoid crosstalk with the bright field signal.

[0066] It should be noted that: in practice, for the convenience of operation, when moving the position of the dark field illumination spot and the dark field slit, the edge of the dark field illumination spot and the edge of the dark field slit are used as reference objects, that is, the position of the dark field illumination spot and the dark field slit is moved by moving the edge of the dark field illumination spot and the edge of the dark field slit.

[0067] It should be noted that the light emitting surface of the second illumination light source 300 should be larger than the moving range of the slit to ensure that sufficient light can pass through the slit at each position.

[0068] Furthermore, the length of the dark field illumination spot does not need to follow the change in imaging magnification, as long as the maximum field of view can be covered. If the target length of the dark field camera is K, the maximum extent of the corresponding imaging field of view, that is, the maximum imaging field of view is the field length of the objective lens 200 at the minimum magnification, which must satisfy K′=K / Mmin. The length of the dark field illumination spot is C=K′+b, where b is the range in which the dark field illumination spot is larger than the field of view required for imaging. Usually, in order to reduce engineering difficulty, some redundancy is eliminated. In this embodiment, b=1~5mm is preferred. The slit length of the dark field slit is configured as C′=C / M D .

[0069] The control method of the semiconductor detection device provided in the above-mentioned embodiment of the present application is provided with multiple magnification objective lenses, and these objective lenses can be flexibly switched according to the requirements of detection accuracy, so as to realize the switching between high detection accuracy and low detection speed and low detection accuracy and high detection speed; the distribution of the dark field illumination spot in the dark field of view is regulated by moving the position of the dark field slit, so that the dark field illumination spot covers the dark field of view corresponding to the dark field detector under the required multiple objective lenses, and at the same time, the dark field illumination spot area is controlled to avoid crosstalk with the bright field signal.

[0070] The above are only preferred embodiments of the present application, and only specifically describe the technical principles of the present application. These descriptions are only for explaining the principles of the present application and cannot be interpreted as limiting the scope of protection of the present application in any way. Based on the explanation here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application, and other specific implementation methods of the present application that can be associated with the technicians in this field without creative work, should be included in the scope of protection of the present application.

Claims

1. A semiconductor testing device, characterized in that: It includes a first illumination light source, an objective lens, a second illumination light source, a dark field slit, a bright field detector and a dark field detector, wherein the magnification of the objective lens is switchable and the position of the dark field slit is movable; The light beam emitted by the first illumination light source is irradiated onto the surface of the wafer to be measured through the objective lens, and the bright field signal light generated by the reflection passes through one side of the optical axis of the objective lens to form a bright field acquisition field which is acquired by the bright field detector, and a bright field image is obtained by imaging; The light beam emitted by the second illumination light source is irradiated to the surface of the wafer under test through the dark field slit, and the dark field acquisition field formed by the scattered dark field signal light passing through the other side of the optical axis of the objective lens is acquired by the dark field detector, and a dark field image is obtained by imaging; wherein: The distribution of the dark field illumination spot on the surface of the wafer to be measured is adjusted by moving the position of the dark field slit, so that the dark field illumination spot covers the dark field acquisition field of view corresponding to the objective lens at any magnification and avoids crosstalk with the bright field acquisition field of view; The bright field image and the dark field image are collected simultaneously and used to obtain the bright field defect characteristics and the dark field defect characteristics of the surface of the wafer under test respectively through image processing.

2. The semiconductor testing device according to claim 1, wherein: The light beam emitted by the second illumination light source is imaged on the surface of the wafer under test via a dark field illumination light path, wherein the dark field illumination light path includes the dark field slit, and a first lens assembly and a second lens assembly arranged in sequence, wherein the first lens assembly and the second lens assembly are used to directly converge the light beam passing through the dark field slit and project it onto the surface of the wafer under test.

3. The semiconductor testing device according to claim 2, wherein: It also includes a spectroscopic element with two reflective surfaces. The bright field signal light and the dark field signal light generated on the surface of the wafer to be measured are respectively incident on the two reflective surfaces of the spectroscopic element through a common imaging optical path. The two reflective surfaces of the spectroscopic element reflect the bright field signal light and the dark field signal light to the bright field detector and the dark field detector respectively.

4. The semiconductor testing device according to claim 3, wherein: The bright field detector and the dark field detector are respectively a bright field camera and a dark field camera, the imaging planes of the bright field camera and the dark field camera are respectively conjugate with the plane where the wafer under test is located, and the field of view center of the bright field camera and the field of view center of the dark field camera are symmetrically distributed with respect to the optical center field of view.

5. The semiconductor testing device according to claim 4, wherein: The off-axis amount L of the dark field camera, the magnification M of the objective lens and the distance l of the dark field illumination spot relative to the optical center field of view are related as follows: l=L / M.

6. The semiconductor testing device according to claim 5, characterized in that: In the dark field illumination light path, the dark field slit is moved on a plane perpendicular to the optical axis to adapt to the magnification of the objective lens; when the magnification of the objective lens is M1, the position of the dark field illumination spot must satisfy l1, and the dark field slit is moved to l′1, and l′ 1= l1 / M D =L / M1 / M D , the M D is the magnification of the dark field illumination light path.

7. The semiconductor testing device according to claim 6, wherein: If the target length of the dark field camera is K, the maximum imaging field of view is the field length of the objective lens at the minimum magnification K′=K / Mmin, the length of the dark field illumination spot must satisfy C=K′+b, b is the range of the dark field illumination spot larger than the field of view required for imaging, b is 1~5mm, and the slit length of the dark field slit is configured as C′=C / M D .

8. The semiconductor testing device according to claim 1, wherein: The light emitting surface of the second illumination light source is larger than the moving range of the dark field slit.

9. The semiconductor testing device according to claim 1, wherein: It also includes a driving device electrically connected to the dark field slit, the driving device is used to drive the dark field slit to move, and the driving device includes a stepping motor, a servo motor or a piezoelectric driver.

10. The semiconductor testing device according to claim 1, wherein: There are two second illumination light sources, and the dark field illumination light paths through which the light beams emitted by the two second illumination light sources pass are symmetrically distributed. The incident plane of the light beams emitted by the second illumination light sources that are incident on the surface of the wafer to be measured after passing through the dark field illumination light path is not perpendicular to the plane where the dark field illumination spot is located.

11. The semiconductor testing device according to claim 1, wherein: There is one second illumination light source, and the incident plane of the light beam emitted by the second illumination light source and incident on the surface of the wafer to be measured after passing through the dark field illumination light path is inclined to the plane where the dark field illumination spot is located.

12. A control method, applied to the semiconductor detection device according to any one of claims 1 to 11, characterized in that: The control method comprises the following steps: Switching the magnification of the objective lens; Acquiring a target position of the dark field slit; The dark field slit is moved on a plane perpendicular to the optical axis of the dark field illumination light path, so that the dark field illumination spot covers the dark field acquisition field corresponding to the current magnification of the objective lens and avoids crosstalk with the bright field acquisition field.

13. The control method according to claim 12, characterized in that: In the dark field illumination light path, the dark field slit is moved on a plane perpendicular to the optical axis to adapt to the magnification of the objective lens; when the magnification of the objective lens is M1, the position of the dark field illumination spot must satisfy l1, and the dark field slit is moved to l′1, and l′ 1= l1 / M D =L / M1 / M D , the M D is the magnification of the dark field illumination light path, and L is the eccentricity of the dark field detector relative to the optical center field of view.

14. The control method according to claim 13, characterized in that: If the target length of the dark field detector is K, the maximum imaging field of view is the field length of the objective lens at the minimum magnification K′=K / Mmin, the length of the dark field illumination spot must satisfy C=K′+b, b is the range of the dark field illumination spot larger than the field of view required for imaging, b is 1~5mm, and the slit length of the dark field slit is configured as C′=C / M D .

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