Device and method for simultaneously and completely equi-optical-path confocal imaging detection of adjacent faces of grains using a glass optical wedge for image splitting

Abstract

The present invention proposes a basic structural principle of a confocal imaging device based on completely equal optical path for adjacent surfaces. In the imaging optical paths of adjacent double surfaces, glass optical wedges are respectively used to implement a new detection device and method for spatial separation of double-sided imaging of semiconductor grains. This new device can obtain completely equal optical path confocal imaging detection for adjacent double surfaces of semiconductor grains simultaneously, and does not require the use of polarization optical elements and polarization CMOS sensors (cameras), effectively reducing the cost of the detection device.

Description

Technical Field:

[0002] The present invention belongs to the fields of optical detection and machine vision, and particularly relates to a device and method for simultaneously and completely equi-optical-path confocal imaging detection of adjacent surfaces of crystal grains using a glass optical wedge for image splitting. Background Art:

[0004] Fully equi-optical-path confocal imaging of the double-sided imaging detection optical path of semiconductor crystal grains is one of the main core technical problems to be solved. Based on different methods, patent applications submitted for the research on the technology of simultaneously detecting defects on adjacent double sides of semiconductor crystal grains include:

[0005] Figure 1 The proposed optical detection device and method well solve the "quasi" confocal imaging detection of adjacent surfaces of semiconductor crystal grains. However, there is still an optical path difference between the adjacent double-sided imaging optical paths. In order to obtain simultaneous confocal imaging of adjacent surfaces, it is necessary to compensate for this small optical path difference by selecting a telecentric imaging lens with a sufficiently large depth of field. Therefore, it is necessary to find a new way for the fully equi-optical-path confocal imaging detection of adjacent surfaces of crystal grains;

[0006] Figure 2 A new method for fully equi-optical-path confocal imaging detection of adjacent surfaces of semiconductor crystal grains based on the time-difference resolution imaging method using a single imaging system is proposed;

[0007] Figure 3 A new method for simultaneously and completely equi-optical-path confocal imaging detection of adjacent surfaces of semiconductor crystal grains based on the dichroic separation imaging method is proposed;

[0008] Figure 4 Using a polarization beam splitter to obtain two illumination light beams with perpendicular polarization directions to respectively illuminate the adjacent double sides of the semiconductor crystal grain to be detected; in addition, a method based on polarization light separation imaging (abbreviated as "polarization image splitting") is proposed, and a device and method for simultaneously and completely equi-optical-path confocal imaging detection of adjacent surfaces of semiconductor crystal grains are realized using a polarization camera;

[0009] Figure 5 A new method is proposed, which is still based on the principle of polarization light separation imaging (abbreviated as "polarization image splitting"), combines a "polarization image splitting prism assembly" and uses an ordinary CMOS or CCD camera to realize the simultaneous and completely equi-optical-path confocal imaging detection of adjacent surfaces of semiconductor crystal grains.

[0010] However, the above-mentioned devices and methods either use polarization optical elements or a CMOS polarization camera, making the optical and precision mechanical structures of the detection system relatively complex and increasing the cost of the detection device. Summary of the Invention:

[0012] The present invention proposes a device and method for simultaneously and completely isoptical-path confocal imaging detection of adjacent surfaces of semiconductor grains using a glass optical wedge for image splitting. The device and method can obtain simultaneous and completely isoptical-path confocal imaging detection of adjacent double surfaces of semiconductor grains without using polarization optical elements and polarization CMOS sensors (cameras), or color cameras and their additional image processing, effectively improving the cost performance and detection efficiency of the detection device.

[0013] The device for simultaneously and completely isoptical-path confocal imaging detection of adjacent surfaces of semiconductor grains using a glass optical wedge for image splitting according to the present invention is characterized in that it includes a CMOS or CCD camera, a telecentric imaging lens, a cubic beam splitter and combiner, a semiconductor grain, and a transparent glass stage for placing the semiconductor grain, which are sequentially arranged in the optical path direction. On the optical path between the semiconductor grain and the cubic beam splitter and combiner, a roof right-angle image-rotating prism, a first glass optical wedge, a side right-angle image-rotating prism, and a second glass optical wedge are respectively arranged in sequence. The side right-angle image-rotating prism and the roof right-angle image-rotating prism are respectively located at the positive side and directly above the top surface of the semiconductor grain. The cubic beam splitter and combiner, the first glass optical wedge, and the roof right-angle image-rotating prism are at the same horizontal height. The side right-angle image-rotating prism, the second glass optical wedge, and the cubic beam splitter and combiner are located on the optical axis of the telecentric imaging lens. At the same time, the first right-angle surface of the side right-angle image-rotating prism faces the first surface of the cubic beam splitter and combiner, the second right-angle surface of the side right-angle image-rotating prism faces the side surface of the semiconductor grain, and the inclined surface of the side right-angle image-rotating prism is inclined with respect to the optical axis of the telecentric imaging lens. The two right-angle surfaces of the roof right-angle image-rotating prism respectively face the top surface of the semiconductor grain and the second surface of the cubic beam splitter and combiner. The surface of the first glass optical wedge close to the cubic beam splitter and combiner forms a glass optical wedge angle with the optical axis of the telecentric imaging lens, and the surface of the second glass optical wedge close to the cubic beam splitter and combiner forms a glass optical wedge angle with the normal of the optical axis of the telecentric imaging lens. An external coaxial illumination light source is provided beside the fourth surface on the opposite side of the second surface of the cubic beam splitter and combiner. The top surface and the side surface of the semiconductor grain are respectively imaged on the camera sensor surface with completely isoptical-path confocal imaging through the right-angle image-rotating prism, the glass optical wedge, and the cubic beam splitter and combiner, so as to obtain independent images of the double surfaces of the semiconductor grain on the CMOS or CCD camera.

[0014] Furthermore, the distance between the center of the cubic beam splitter and combiner and the center of the inclined surface of the side right-angle image-rotating prism is D / 2 + d. The cubic beam splitter and combiner and the inclined surface of the roof right-angle image-rotating prism are at the same horizontal height, and the distance between them is D / 2 + d. The working distance WD of the side imaging optical path is WD = D / 2 + d / 2, and the working distance WD of the top surface imaging optical path is WD = WD = D / 2 + d / 2, where D is the width of the transparent glass stage and d is the right-angle side length of the prism. The working distance WD of the top surface imaging optical path of the semiconductor grain is WD = D / 2 + d / 2 = 30 mm, and the working distance WD of the side imaging optical path is WD = D / 2 + d / 2 = 30 mm.

[0015] Furthermore, the glass optical wedge causes the double-sided imaging beams to generate angular displacements γ1 and γ2 on both sides of the center (optical axis) of the cube beam splitter and combiner. The magnitudes of γ1 and γ2 depend on the thickness t of the glass optical wedge, the refractive index n of the glass, as well as the glass optical wedge angles α1 and α2, and the angles θ1 and θ2 between the normal of the glass optical wedge surface and the optical axis. The angular displacement γ = γ1 + γ2 by which the images of adjacent faces of the semiconductor grain are separated in space at the output of the cube beam splitter and combiner. The thickness t of the first and second glass optical wedges is 2 mm, the glass optical wedge angle α = 2°, and the material of the glass optical wedge is K9. The calculated angular displacements γ1 = γ2 = (n - 1) × α = 1.03°, and γ = 2.06°.

[0016] Furthermore, the size of the above-mentioned top surface right-angle image-rotating prism is 15 * 15 * 15 mm, the size of the side surface right-angle image-rotating prism is 15 * 15 * 15 mm, and the size of the cube beam splitter and combiner is 15 * 15 * 15 mm. A square symmetric optical path structure with a side length of D / 2 + d = 37.5 mm is formed by connecting the center of the cube beam splitter and combiner, the center of the reflecting surface of the right-angle image-rotating prism, and the center of the semiconductor grain.

[0017] Furthermore, the double-image separation δ = γ × L = 1.8 mm generated by the two glass optical wedges, the focal length f = 51.5 mm, WD = 110 mm, L = 50 mm. The angular tolerance (≤ 30 arc seconds) of the cube beam splitter and combiner and the right-angle image-rotating prism should control the double-image angular displacement error within 2 arc minutes.

[0018] Furthermore, due to the angular error and assembly error of the above-mentioned cube beam splitter and combiner or the right-angle image-rotating prism, which cause the angular deviation of the double-sided imaging spatial optical path, within the meridional plane (y - z plane, the z-axis is along the optical axis direction), the errors in the meridional plane are corrected and compensated by slightly rotating the glass micro-optical wedge around the x-axis to adjust θ1 and θ2. Due to the angular manufacturing error and assembly error of the cube beam splitter and combiner or the right-angle image-rotating prism, which cause the deviation of the relative spatial position or angular displacement of the double-sided imaging. Similarly, in the sagittal plane (x - z plane), the relative spatial position or angular displacement deviation caused by the angular manufacturing error and assembly error of the cube beam splitter and combiner or the right-angle image-rotating prism can be corrected and compensated by generating a linear displacement by rotating the glass optical wedge with a thickness of t around the y-axis by a small angle.

[0019] Furthermore, the above-mentioned coaxial external illumination light source is a monochromatic light, or a quasi-monochromatic light source or white light with a certain spectral bandwidth.

[0020] The present invention relates to a method for simultaneously completely equal optical path confocal imaging detection of adjacent faces of semiconductor grains using a glass optical wedge for image splitting, characterized in that: the device for simultaneously completely equal optical path confocal imaging detection of adjacent faces of semiconductor grains using a glass optical wedge for image splitting includes a CMOS or CCD camera, a telecentric imaging lens, a cube beam splitter and combiner, a semiconductor grain, and a transparent glass stage for placing the semiconductor grain, which are sequentially arranged in the optical path direction. On the optical path between the semiconductor grain and the cube beam splitter and combiner, there are respectively a roof right-angle image rotation prism, a first glass optical wedge, a side right-angle image rotation prism, and a second glass optical wedge. The side right-angle image rotation prism and the roof right-angle image rotation prism are respectively located on the positive side and directly above the top surface of the semiconductor grain. The cube beam splitter and combiner, the first glass optical wedge, and the roof right-angle image rotation prism are at the same horizontal height. The side right-angle image rotation prism, the second glass optical wedge, and the cube beam splitter and combiner are located on the optical axis of the telecentric imaging lens. At the same time, the first right-angle face of the side right-angle image rotation prism faces the first face of the cube beam splitter and combiner, the second right-angle face of the side right-angle image rotation prism faces the side face of the semiconductor grain, and the inclined face of the side right-angle image rotation prism is inclined with respect to the optical axis of the telecentric imaging lens. The two right-angle faces of the roof right-angle image rotation prism face the top surface of the semiconductor grain and the second face of the cube beam splitter and combiner respectively. The surface of the first glass optical wedge close to the cube beam splitter and combiner forms a glass optical wedge angle with the optical axis of the telecentric imaging lens, and the surface of the second glass optical wedge close to the cube beam splitter and combiner forms a glass optical wedge angle with the normal of the optical axis of the telecentric imaging lens. A coaxial external illumination light source is provided beside the fourth face opposite to the second face of the cube beam splitter and combiner. The top surface and the side face of the semiconductor grain are imaged on the camera sensor surface with completely equal optical path confocal imaging through the right-angle image rotation prism, the glass optical wedge, and the cube beam splitter and combiner respectively, so as to obtain independent images of both sides of the semiconductor grain on the CMOS or CCD camera. During operation,

[0021] Dual-sided illumination optical path:

[0022] When the coaxial external illumination light source passes through the cube beam splitter and combiner, it is divided into two illumination light beams: one light beam illuminates the top surface of the semiconductor grain to be measured located on the glass stage turntable after passing through the roof right-angle image rotation prism and the first glass optical wedge; and the other illumination light beam illuminates the side face of the semiconductor grain to be measured after passing through the side right-angle image rotation prism and the second glass optical wedge. The two illumination light beams illuminate two adjacent faces of the semiconductor grain respectively;

[0023] Imaging detection optical path:

[0024] Diffuse light is generated on two adjacent faces of the illuminated semiconductor die. The imaging light beam from the top surface of the semiconductor die is incident on the first glass optical wedge with a thickness of t and a wedge angle of α1 through a right-angled image-rotating prism on the top surface, and the imaging light beam emerging from the first glass optical wedge generates an angular displacement γ1 towards the optical axis side, and then reaches the reference output surface after being reflected by a cube beam splitter and image combiner; while the imaging light beam from the side surface of the semiconductor die is incident on the second glass optical wedge with a thickness of t and a wedge angle of α2 through a right-angled image-rotating prism on the side surface, and the imaging light beam emerging from the second glass optical wedge also generates an angular displacement γ2 towards the other side of the optical axis, and then reaches the reference output surface after being transmitted by the cube beam splitter and image combiner. The angular displacement of adjacent faces output from the cube beam splitter and image combiner is γ = γ1 + γ2, and independent images of the two sides are respectively obtained on a CMOS or CCD camera.

[0025] Advantages of the detection device and method of the present invention:

[0026] 1) The present invention can realize simultaneous full equal optical path confocal imaging detection of adjacent double sides of a semiconductor die, without the need to use a large depth-of-field telecentric lens to compensate for the optical path difference of adjacent double side imaging;

[0027] 2) The use of glass optical wedges in the imaging optical path of the present invention can obtain the expected angular displacement γ or spatial separation δ of double side imaging. The double image interval δ can be adjusted, and for a given thickness t of the parallel plate and the refractive index n of the glass, the size of δ depends on the glass wedge angle α;

[0028] 3) The present invention can also use the glass wedge angle to correct and compensate for the deviation of the relative spatial position or angular displacement of double side imaging caused by the angular manufacturing error and assembly error of the cube prism or right-angled image-rotating prism;

[0029] 4) The present invention uses ordinary glass wedge angles and CMOS or CCD cameras, without the need to use polarization optical elements and polarization CMOS sensors (cameras), which can effectively reduce the cost of the detection device and improve the performance-price ratio of the detection device;

[0030] 5) The structure of the detection device for simultaneous imaging of adjacent double sides of a semiconductor die is simple and compact, easy to assemble and debug, and has good reliability. Description of the drawings:

[0032] Figures 1-5 is an existing optical device for detecting adjacent faces of a semiconductor die;

[0033] Among them, 1 is a black and white camera, 2 is a telecentric imaging lens, 3a or 3b is an image-rotating prism, 3 is an image combining optical element, 4 is a semiconductor die, 5 is a transparent glass stage, 6 or 6a or 6b is an image-rotating prism, 7 or 7a and 7b are light sources, 8 and 9 are filters; 8a is a polarization prism; 8b is a roof prism;

[0034] Figure 6It is a schematic diagram of the principle of the device of the present invention;

[0035] Figure 7 It is a schematic diagram of the principle of a glass optical wedge.

[0036] Figure 8 It is a schematic diagram of an embodiment of the corresponding dimensions of the device of the present invention; Specific implementation manner:

[0038] As Figure 6 shown, the device for simultaneously and completely equally optical path confocal imaging of adjacent surfaces of semiconductor grains using a glass optical wedge to split images in the present invention includes a CMOS or CCD camera 1, a telecentric imaging lens 2, a cube beam splitter and combiner 3, a semiconductor grain 6, and a transparent glass stage 7 for placing the semiconductor grain, which are sequentially arranged in the optical path direction. On the optical path between the semiconductor grain 6 and the cube beam splitter and combiner 3, a top surface right-angle image rotation prism 4a, a first glass optical wedge 5a, a side surface right-angle image rotation prism 4b, and a second glass optical wedge 5b are respectively arranged in sequence. The side surface right-angle image rotation prism 4b and the top surface right-angle image rotation prism 4a are respectively located at the positive side and directly above the top surface of the semiconductor grain 6. The cube beam splitter and combiner 3, the first glass optical wedge 5a, and the top surface right-angle image rotation prism 4a are at the same horizontal height; the side surface right-angle image rotation prism 4b, the second glass optical wedge 5b, and the cube beam splitter and combiner 3 are located on the optical axis A of the telecentric imaging lens. At the same time, the first right-angle surface 401b of the side surface right-angle image rotation prism faces the first surface 301 of the cube beam splitter and combiner, the second right-angle surface 402b of the side surface right-angle image rotation prism faces the side surface of the semiconductor grain, and the inclined surface 403b of the side surface right-angle image rotation prism is inclined with respect to the optical axis of the telecentric imaging lens; the two right-angle surfaces 401a and 402a of the top surface right-angle image rotation prism respectively face the top surface of the semiconductor grain and the second surface 302 of the cube beam splitter and combiner; the surface 501a of the first glass optical wedge 5a close to the cube beam splitter and combiner forms a glass optical wedge angle with the optical axis of the telecentric imaging lens, and the surface 501b of the second glass optical wedge 5b close to the cube beam splitter and combiner forms a glass optical wedge angle with the normal of the optical axis of the telecentric imaging lens. A coaxial external illumination source 8 is provided beside the fourth surface 304 on the opposite side of the second surface of the cube beam splitter and combiner. The top surface and the side surface of the semiconductor grain are imaged on the camera sensor surface with completely equal optical path and confocal imaging through the right-angle image rotation prisms 4a, 4b, the glass optical wedges 5a, 5b, and the cube beam splitter and combiner, so as to obtain independent images of both sides of the semiconductor grain on the CMOS or CCD camera.

[0039] The distance between the center of the above-mentioned cubic beam-splitting image combiner and the center of the inclined plane of the side right-angle image-rotating prism is D / 2 + d. The cubic beam-splitting image combiner and the inclined plane of the top right-angle image-rotating prism are at the same horizontal height, and the distance between them is D / 2 + d. The working distance WD of the side imaging optical path is WD = D / 2 + d / 2, and the working distance WD of the top imaging optical path is WD = D / 2 + d / 2. D is the width of the transparent glass stage, and d is the right-angle side length of the prism; the working distance WD of the semiconductor grain top imaging optical path is WD = D / 2 + d / 2 = 30 mm, and the working distance WD of the side imaging optical path is WD = D / 2 + d / 2 = 30 mm.

[0040] The glass optical wedges cause angular displacements γ1 and γ2 of the double-sided imaging beams on both sides of the center (optical axis) of the cubic beam-splitting image combiner, and the magnitudes of γ1 and γ2 depend on the thickness t of the glass optical wedges, the glass refractive index n, the glass optical wedge angles α1 and α2, and the angles θ1 and θ2 between the normal of the glass optical wedge surface and the optical axis, as Figure 7 shown. The angular displacement of the images of adjacent faces of the semiconductor grain separated in space at the output of the cubic beam-splitting image combiner is γ = γ1 + γ2; the thickness t of the first and second glass optical wedges is t = 2 mm, the glass optical wedge angle α = 2°, the material of the glass optical wedge is K9, and the calculated angular displacements γ1 = γ2 = (n - 1) x α = 1.03°, γ = 2.06°.

[0041] As Figure 8 shown, the dimensions of the above-mentioned top right-angle image-rotating prism are 15 * 15 * 15 mm, the dimensions of the side right-angle image-rotating prism are 15 * 15 * 15 mm, and the dimensions of the cubic beam-splitting image combiner are 15 * 15 * 15 mm; the center of the cubic beam-splitting image combiner, the center of the reflecting surface of the right-angle image-rotating prism, and the center of the semiconductor grain are connected to form a square symmetric optical path structure with a side length of D / 2 + d = 37.5 mm.

[0042] The double-image separation δ = γ x L = 1.8 mm produced by the two glass optical wedges, the focal length f = 51.5 mm, WD = 110 mm, L = 50 mm; the angular tolerance (≤30 arc seconds) of the cubic beam-splitting image combiner and the right-angle image-rotating prism, and the double-image angular displacement error generated should be controlled within 2 arc minutes.

[0043] The angular deviation of the double-sided imaging spatial optical path caused by the angular error and assembly error of the above-mentioned cubic beam-splitting image combiner or right-angle image-rotating prism can be corrected and compensated for the error in the meridional plane (y-z plane, the z-axis is along the optical axis direction) by rotating the glass optical wedges around the x-axis to fine-tune θ1 and θ2; similarly, due to the angular error and assembly error of the cubic beam-splitting image combiner or right-angle image-rotating prism, the angular deviation of the double-sided imaging spatial optical path can also be corrected and compensated for the error in the sagittal plane (x-z plane) by rotating the glass optical wedge with a thickness of t around the y-axis by a small angle to generate a linear displacement.

[0044] Furthermore, the above coaxial external illumination light source is a monochromatic light, or a quasi-monochromatic light source or white light with a certain spectral bandwidth.

[0045] The cubic beam-splitting image combiner can also be called a cubic beam-splitting image combiner / image combiner, cubic image combiner. It is a common optical device. A beam-splitting film with a transmission and reflection ratio of 50%:50% can be plated on the inclined surface of a right-angle prism, and the inclined surfaces of two right-angle reflecting prisms are glued together.

[0046] The present invention uses a method for simultaneously and completely equal optical path confocal imaging detection of adjacent surfaces of semiconductor grains by using a glass optical wedge for image splitting. The characteristics are as follows: The device for simultaneously and completely equal optical path confocal imaging detection of adjacent surfaces of semiconductor grains by using a glass optical wedge includes a CMOS or CCD camera, a telecentric imaging lens, a cubic beam-splitting image combiner, a semiconductor grain, and a transparent glass stage for placing the semiconductor grain, which are sequentially arranged in the optical path direction. On the optical path between the semiconductor grain and the cubic beam-splitting image combiner, a top surface right-angle image rotation prism, a first glass optical wedge, a side surface right-angle image rotation prism, and a second glass optical wedge are sequentially provided. The side surface right-angle image rotation prism and the top surface right-angle image rotation prism are respectively located on the positive side and directly above the top surface of the semiconductor grain. The cubic beam-splitting image combiner, the first glass optical wedge, and the top surface right-angle image rotation prism are at the same horizontal height. The side surface right-angle image rotation prism, the second glass optical wedge, and the cubic beam-splitting image combiner are located on the optical axis of the telecentric imaging lens. At the same time, the first right-angle surface of the side surface right-angle image rotation prism faces the first surface of the cubic beam-splitting image combiner, the second right-angle surface of the side surface right-angle image rotation prism faces the side surface of the semiconductor grain, and the inclined surface of the side surface right-angle image rotation prism is inclined with respect to the optical axis of the telecentric imaging lens. The two right-angle surfaces of the top surface right-angle image rotation prism respectively face the top surface of the semiconductor grain and the second surface of the cubic beam-splitting image combiner. The surface of the first glass optical wedge close to the cubic beam-splitting image combiner forms a glass optical wedge angle with the optical axis of the telecentric imaging lens, and the surface of the second glass optical wedge close to the cubic beam-splitting image combiner forms a glass optical wedge angle with the normal of the optical axis of the telecentric imaging lens. A coaxial external illumination light source is provided beside the fourth surface opposite to the second surface of the cubic beam-splitting image combiner. The top surface and the side surface of the semiconductor grain are respectively imaged on the camera sensor surface with completely equal optical path confocal imaging through the right-angle image rotation prism, the glass optical wedge, and the cubic beam-splitting image combiner, so as to obtain independent images of both sides of the semiconductor grain on the CMOS or CCD camera. When working,

[0047] Dual-sided illumination optical path:

[0048] When the coaxial external illumination light source passes through the cubic beam-splitting image combiner, it is divided into two illumination beams: One beam of light illuminates the top surface of the semiconductor grain to be measured located on the glass stage turntable after passing through the top surface right-angle image rotation prism and the first glass optical wedge; and the other illumination beam illuminates the side surface of the semiconductor grain to be measured after passing through the side surface right-angle image rotation prism and the second glass optical wedge. The two illumination beams respectively illuminate two adjacent surfaces of the semiconductor grain.

[0049] Imaging detection optical path:

[0050] Diffuse light is generated on two adjacent surfaces of the illuminated semiconductor die. The imaging light beam on the top surface of the semiconductor die is incident on the first glass optical wedge with a thickness of t and a wedge angle of α1 through a right-angle image-rotating prism on the top surface. The imaging light beam emerging from the first glass optical wedge generates an angular displacement γ1 towards the optical axis side, and then reaches the reference output surface after being reflected by a cube beam splitter and image combiner; while the imaging light beam on the side surface of the semiconductor die is incident on the second glass optical wedge with a thickness of t and a wedge angle α2 through a right-angle image-rotating prism on the side surface. The imaging light beam emerging from the second glass optical wedge also generates an angular displacement γ2 towards the other side of the optical axis, and then reaches the reference output surface after being transmitted through the cube beam splitter and image combiner. The angular displacement of the adjacent surfaces output from the cube beam splitter and image combiner is γ = γ1 + γ 2， The spatial equivalent interval δ of the adjacent surfaces of the die corresponding to this angular displacement is δ = γ x L (L is the distance between the glass optical wedge and the reference output surface of the cube beam splitter and image combiner 3), and independent images of the two surfaces are respectively obtained on a CMOS or CCD camera.

[0051] The optical device of the present invention is similar to the structure of a Michelson double-beam equal-arm interferometer. In the imaging optical paths of the adjacent two surfaces of the present invention device, glass optical wedges with relatively small refracting prism wedge angles (referred to as glass optical wedges, i.e., the above-mentioned first glass optical wedge and second glass optical wedge) are respectively used to achieve the angular displacement γ of the imaging optical paths of the two surfaces of the die. The spatial equivalent interval δ of the object space of the adjacent surfaces of the die corresponding to this angular displacement is δ = γ x L (L is the object distance). Under the condition of satisfying the completely equal optical path and confocal for the two-surface imaging, the spatial separated imaging of the adjacent surfaces is obtained, so that the simultaneous completely equal optical path and confocal imaging detection of the adjacent two surfaces of the semiconductor die can be realized.

[0052] The spatial positions of the double images of the adjacent surfaces of the semiconductor die of the present device are separated by δ' on the sensor surface of the CMOS camera, or the equivalent interval δ' of the adjacent two surfaces of the object space of the die is δ' = δ / β (β is the magnification of the telecentric imaging lens), and the imaging of the adjacent two surfaces of the semiconductor die satisfies the completely equal optical path and confocal condition.

[0053] Advantages of the detection device and method of the present invention:

[0054] 1) The present invention can realize the simultaneous completely equal optical path and confocal imaging detection of the adjacent two surfaces of the semiconductor die, without the need to use a large-depth-of-field telecentric lens to compensate for the optical path difference of the adjacent two-surface imaging;

[0055] 2) The use of the glass optical wedge in the imaging optical path of the present invention can obtain the expected angular displacement γ or spatial separation δ of the two-surface imaging. The double-image interval δ can be adjusted, and for a given thickness t of the parallel plate and the refractive index n of the glass, the magnitude of δ depends on the glass optical wedge angle α;

[0056] 3) The present invention can also use the glass optical wedge angle to correct and compensate for the deviation of the relative spatial position or angular displacement of the double-sided imaging caused by the angular manufacturing error and assembly error of the cubic prism or the right-angle image-rotating prism;

[0057] 4) The present invention uses an ordinary glass optical wedge angle and a CMOS or CCD camera, without the need to use polarization optical elements and polarization CMOS sensors (cameras), and at the same time has a stronger function of double-sided image splitting and manufacturing error compensation; this device can effectively reduce the cost of the detection device and improve the performance-price ratio of the detection device;

[0058] 5) The double-sided simultaneous imaging detection device for semiconductor grains has a simple and compact structure, is easy to assemble and debug, and has good reliability.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A detection device for simultaneously and completely equal optical path confocal imaging of adjacent faces of grains using a glass optical wedge for image splitting, characterized in that: It includes a CMOS or CCD camera, a telecentric imaging lens, a cube beam splitter-combiner, a semiconductor die, and a transparent glass stage for placing the semiconductor die, which are sequentially arranged in the optical path direction. On the optical path between the semiconductor die and the cube beam splitter-combiner, there are respectively a roof right-angle image-rotating prism, a first glass optical wedge, a side right-angle image-rotating prism, and a second glass optical wedge in sequence. The side right-angle image-rotating prism and the roof right-angle image-rotating prism are respectively located at the positive side and directly above the top surface of the semiconductor die. The cube beam splitter-combiner, the first glass optical wedge, and the roof right-angle image-rotating prism are at the same horizontal height. The side right-angle image-rotating prism, the second glass optical wedge, and the cube beam splitter-combiner are located on the optical axis of the telecentric imaging lens. At the same time, the first right-angle surface of the side right-angle image-rotating prism faces the first surface of the cube beam splitter-combiner, the second right-angle surface of the side right-angle image-rotating prism faces the side surface of the semiconductor die, and the inclined surface of the side right-angle image-rotating prism is inclined with respect to the optical axis of the telecentric imaging lens. The two right-angle surfaces of the roof right-angle image-rotating prism respectively face the top surface of the semiconductor die and the second surface of the cube beam splitter-combiner. The surface of the first glass optical wedge close to the cube beam splitter-combiner forms a glass optical wedge angle with the optical axis of the telecentric imaging lens, and the surface of the second glass optical wedge close to the cube beam splitter-combiner forms a glass optical wedge angle with the normal of the optical axis of the telecentric imaging lens. There is a coaxial external illumination source beside the fourth surface opposite to the second surface of the cube beam splitter-combiner. The top surface and the side surface of the semiconductor die are respectively imaged on the camera sensor surface with completely equal optical path and confocal through the right-angle image-rotating prism, the glass optical wedge, and the cube beam splitter-combiner, so as to obtain independent images of both sides of the semiconductor die on the CMOS or CCD camera. The distance between the center of the cube beam splitter-combiner and the center of the inclined surface of the side right-angle image-rotating prism is D / 2 + d. The cube beam splitter-combiner and the inclined surface of the roof right-angle image-rotating prism are at the same horizontal height, and the distance between them is D / 2 + d. The working distance of the side imaging optical path WD = D / 2 + d / 2, and the working distance of the top surface imaging optical path WD = WD = D / 2 + d / 2, where D is the width of the transparent glass stage and d is the right-angle side length of the prism. The working distance WD of the imaging optical path on the top surface of the semiconductor die is WD = D / 2 + d / 2 = 30 mm, and the working distance WD of the imaging optical path on the side surface is WD = D / 2 + d / 2 = 30 mm; the glass optical wedges cause angular displacements γ1 and γ2 of the double-sided imaging beams on both sides of the central optical axis of the cube beam splitter and combiner, and the magnitudes of γ1 and γ2 depend on the thickness t of the glass optical wedges, the refractive index n of the glass, and the glass optical wedge angles α1 and α2. The angular displacement γ = γ1 + γ2 at which the images of adjacent surfaces of the semiconductor die output by the cube beam splitter and combiner are separated in space; the thickness t of the first and second glass optical wedges is t = 2 mm, the glass optical wedge angle α = 2°, and the material of the glass optical wedges is K9. The calculated angular displacements γ1 = γ2 = (n - 1) x α = 1.03°, γ = 2.06°; the size of the top surface right-angle image-rotating prism is 15*15*15 mm, the size of the side surface right-angle image-rotating prism is 15*15*15 mm, and the size of the cube beam splitter and combiner is 15*15*15 mm; the center of the cube beam splitter and combiner, the center of the reflecting surface of the right-angle image-rotating prism, and the center of the semiconductor die are connected to form a square symmetric optical path structure with a side length of D / 2 + d = 37.5 mm; the double-image separation δ = γ x L = 1.8 mm generated by the two glass optical wedges, the focal length f = 51.5 mm, WD = 110 mm, L = 50 mm, and L is the distance between the glass optical wedges and the reference output surface of the cube beam splitter and combiner; the angular tolerance of the cube beam splitter and combiner and the right-angle image-rotating prism is ≤ 30 arc seconds, and the double-image angular displacement error generated should be controlled within 2 arc minutes; due to the angular error and assembly error of the cube beam splitter and combiner or the right-angle image-rotating prism, resulting in an angular deviation of the double-sided imaging spatial optical path, in the meridional plane y-z plane, the errors in the meridional plane are corrected and compensated by slightly rotating the glass micro-optical wedges around the x-axis by θ1 and θ2. Due to the angular manufacturing error and assembly error of the cube beam splitter and combiner or the right-angle image-rotating prism, resulting in a deviation in the relative spatial position or angular displacement of the double-sided imaging; similarly, in the sagittal plane x-z plane, a linear displacement can be generated by rotating the glass optical wedge with a thickness of t around the y-axis by a small angle to correct and compensate for the deviation in the relative spatial position or angular displacement of the double-sided imaging due to the angular manufacturing error and assembly error of the cube beam splitter and combiner or the right-angle image-rotating prism.

2. The grain adjacent surface simultaneous complete equal optical path confocal imaging detection device using a glass optical wedge for image splitting according to claim 1, characterized in that: The coaxial external illumination light source is a monochromatic light, or a quasi-monochromatic light source or white light with a certain spectral bandwidth.

3. A method for simultaneously and completely detecting the adjacent faces of grains with equal optical path confocal imaging using a glass optical wedge for image splitting, characterized in that: The grain adjacent surface simultaneous complete equal optical path confocal imaging detection device using a glass optical wedge for image splitting includes a CMOS or CCD camera, a telecentric imaging lens, a cube beam splitter and combiner, a semiconductor grain, and a transparent glass stage for placing the semiconductor grain, which are sequentially arranged in the optical path direction. On the optical path between the semiconductor grain and the cube beam splitter and combiner, a top right angle image rotation prism, a first glass optical wedge, a side right angle image rotation prism, and a second glass optical wedge are sequentially provided. The side right angle image rotation prism and the top right angle image rotation prism are respectively located at the positive side and directly above the top surface of the semiconductor grain. The cube beam splitter and combiner, the first glass optical wedge, and the top right angle image rotation prism are at the same horizontal height. The side right angle image rotation prism, the second glass optical wedge, and the cube beam splitter and combiner are located on the optical axis of the telecentric imaging lens. At the same time, the first right angle surface of the side right angle image rotation prism faces the first surface of the cube beam splitter and combiner, the second right angle surface of the side right angle image rotation prism faces the side surface of the semiconductor grain, and the inclined surface of the side right angle image rotation prism is inclined with respect to the optical axis of the telecentric imaging lens. The two right angle surfaces of the top right angle image rotation prism respectively face the top surface of the semiconductor grain and the second surface of the cube beam splitter and combiner. The surface of the first glass optical wedge close to the cube beam splitter and combiner forms a glass optical wedge angle with the optical axis of the telecentric imaging lens. The surface of the second glass optical wedge close to the cube beam splitter and combiner forms a glass optical wedge angle with the normal of the optical axis of the telecentric imaging lens. A coaxial external illumination light source is provided beside the fourth surface on the opposite side of the second surface of the cube beam splitter and combiner. The top surface and the side surface of the semiconductor grain are imaged on the camera sensor surface with complete equal optical path confocal imaging through the right angle image rotation prism, the glass optical wedge, and the cube beam splitter and combiner respectively, so as to obtain independent images of both sides of the semiconductor grain on the CMOS or CCD camera. During operation, Dual-sided illumination optical path: When the coaxial external illumination light source passes through the cube beam splitter and combiner, it is divided into two illumination light beams: one light beam illuminates the top surface of the semiconductor grain to be measured on the glass stage turntable after passing through the top right angle image rotation prism and the first glass optical wedge; while the other illumination light beam illuminates the side surface of the semiconductor grain to be measured after passing through the side right angle image rotation prism and the second glass optical wedge. The two illumination light beams respectively illuminate two adjacent surfaces of the semiconductor grain; Imaging detection optical path: The two illuminated adjacent surfaces of the semiconductor grain generate diffused light. The imaging light beam of the top surface of the semiconductor grain is incident on the first glass optical wedge with a thickness of t and a wedge angle of α1 through the top right angle image rotation prism. The imaging light beam emerging from the first glass optical wedge generates an angular displacement γ1 towards the optical axis side, and then reaches the reference output surface after being reflected by the cube beam splitter and combiner; while the imaging light beam of the side surface of the semiconductor grain is incident on the second glass optical wedge with a thickness of t and a wedge angle α2 through the side right angle image rotation prism. The imaging light beam emerging from the second glass optical wedge also generates an angular displacement γ2 towards the other side of the optical axis, and then reaches the reference output surface after passing through the cube beam splitter and combiner. The angular displacement of the adjacent surfaces output from the cube beam splitter and combiner is γ = γ1 + γ2, and independent images of both sides are respectively obtained on the CMOS or CCD camera.

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