CN114527142A - Silicon wafer back inspection equipment and back inspection method - Google Patents

Silicon wafer back inspection equipment and back inspection method Download PDF

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Publication number
CN114527142A
CN114527142A CN202210071123.9A CN202210071123A CN114527142A CN 114527142 A CN114527142 A CN 114527142A CN 202210071123 A CN202210071123 A CN 202210071123A CN 114527142 A CN114527142 A CN 114527142A
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center
silicon wafer
connecting rod
groove
acquiring
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孙良峰
沈锦华
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Hefei Yuwei Semiconductor Technology Co ltd
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Hefei Yuwei Semiconductor Technology Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/9501—Semiconductor wafers
    • G01N21/9505—Wafer internal defects, e.g. microcracks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention discloses silicon wafer back inspection equipment and a back inspection method, wherein a spiral guide rail seat in the equipment is provided with a first groove which is spirally arranged from the center to the edge, one end of a connecting rod is connected to the center of the spiral guide rail seat through a rotating shaft, the other end of the connecting rod makes circular motion around the center of the spiral guide rail seat, a sliding block is sleeved on the connecting rod, one side of the sliding block, which is adjacent to the first groove, is provided with a first roller, one side of the sliding block, which is far away from the first groove, is provided with a visual detection device, and at least part of the first roller is arranged in the first groove; the driving device is connected with the rotating shaft and used for driving the connecting rod to rotate so as to drive the first roller to move along the first groove and simultaneously drive the sliding block to slide on the connecting rod, so that the moving track of the visual detection device is a spiral track; the bearing table is used for bearing a silicon wafer to be detected, and the silicon wafer to be detected is back to the visual field direction of the visual detection device, so that the detection precision can be ensured on the basis of simplifying the structure of the spiral scanning equipment.

Description

Silicon wafer back inspection equipment and back inspection method
Technical Field
The embodiment of the invention relates to the technical field of semiconductors, in particular to silicon wafer back inspection equipment and a back inspection method.
Background
The detection of the back of a silicon wafer is receiving more and more attention, and the existing scheme is to take a picture by a linear line-by-line scanning (as shown in fig. 1), a circle-by-circle step scanning (as shown in fig. 2) or a spiral scanning mode (as shown in fig. 3) to obtain image information and then identify defects by using an image algorithm. The prior scheme has the following problems: 1) the coverage area of each line of scanning of linear line-by-line scanning is small, the reciprocating motion efficiency is low, and the whole scanning process is discontinuous due to line-to-line switching, so that the efficiency is influenced; 2) the step between each circle of the circle-by-circle step scanning mode is simpler than the line-by-line scanning, but the scanning process is also discontinuous, and the efficiency is influenced; 3) the spiral scanning can ensure the continuous scanning process and improve the motion detection efficiency, but the existing mode is complex to realize at present, the spiral motion is realized by multi-axis cooperation, and the requirement on the coordination of controlling the motion of each axis is high.
Disclosure of Invention
The invention provides silicon wafer back inspection equipment and a back inspection method, which can ensure the detection precision on the basis of simplifying the structure of spiral scanning equipment.
In order to achieve the above object, an embodiment of a first aspect of the present invention provides a silicon wafer back inspection apparatus, including: the spiral guide rail seat, the connecting rod and the sliding block;
the spiral guide rail seat is provided with first grooves which are spirally arranged from the center to the edge, one end of the connecting rod is connected to the center of the spiral guide rail seat through a rotating shaft, the other end of the connecting rod makes circular motion around the center of the spiral guide rail seat, the sliding block is sleeved on the connecting rod, one side, close to the first groove, of the sliding block is provided with a first roller, one side, far away from the first groove, of the sliding block is provided with a visual detection device, and at least part of the first roller is arranged in the first groove;
the driving device is connected with the rotating shaft and used for driving the connecting rod to rotate so as to drive the first roller to move along the first groove and simultaneously drive the sliding block to slide on the connecting rod, so that the moving track of the visual detection device is a spiral track;
and the bearing table is used for bearing a silicon wafer to be detected, and the silicon wafer to be detected faces to the visual field direction of the visual detection device.
According to an embodiment of the present invention, the silicon wafer back inspection apparatus further includes: the second roller is connected with the other end of the connecting rod, the second roller winds a first rolling shaft and contacts the outer wall of the spiral guide rail seat to roll, the first rolling shaft is arranged in parallel with the central shaft of the spiral guide rail seat, and the first rolling shaft takes the center of the spiral guide rail seat as the circle center to perform circular motion.
According to an embodiment of the present invention, the silicon wafer back inspection apparatus further includes: the second roller is connected with the other end of the connecting rod, rolls around a second rolling shaft, and the second rolling shaft is arranged along the radial direction of the track of the other end of the connecting rod which does circular motion;
and a circular second groove is formed in the outer edge of the spiral guide rail seat, and the second roller is in contact with the groove bottom of the second groove and rolls.
According to one embodiment of the invention, the pitch of the first groove of the screw thread arrangement on the screw guide seat is smaller than or equal to the visual field distance of the visual detection device along the pitch direction.
According to one embodiment of the invention, the visual detection device is a CCD camera or a CMOS camera.
In order to achieve the above object, an embodiment of the second aspect of the present invention further provides a silicon wafer back inspection method, which is implemented based on the foregoing silicon wafer back inspection device, and includes the following steps:
acquiring a track curve equation of the center of the visual detection device in a data fitting mode;
acquiring any one image acquired by the visual detection device;
identifying a first location of a defect in the image under the visual inspection device coordinate system;
according to the track curve equation, acquiring a second position of the center of the visual detection device relative to the rotation center of the connecting rod;
acquiring a third position of the center of the bearing table relative to the rotation center of the connecting rod;
acquiring a fourth position of the center of the silicon wafer to be tested relative to the center of the bearing table;
and acquiring the position of the defect relative to the center of the silicon wafer to be detected according to the first position, the second position, the third position and the fourth position.
According to one embodiment of the invention, the trajectory profile equation satisfies the following formula:
Figure BDA0003482219570000031
wherein r represents the distance between the upper point of the trajectory curve and the connecting line of the rotation center points of the connecting rods, and r0Represents a distance from an edge of the screw guide holder to a rotation center of the link, θ represents an angle of rotation of the link, Δ d represents a pitch of the first groove, c0，c1，c2Representing error term coefficients, (x, y) representing position coordinates describing a point on the trajectory curve under a rectangular coordinate system defined as: and taking the rotation center of the connecting rod as an origin, taking a connecting line of the starting point and the end point of the first groove as an X axis, and taking the Y axis direction to be vertical to the X axis, wherein the rotation center of the connecting rod is coincided with the starting point of the first groove.
According to one embodiment of the invention, the error term coefficient c0，c1，c2Satisfies the following conditions:
Figure BDA0003482219570000041
wherein, thetaiIndicating the rotation angle of the connecting rod corresponding to the ith mark theoretically, (x)i,yi) And the actual position of the aligned ith mark is shown, and a plurality of marks are uniformly distributed on the reference silicon wafer.
According to an embodiment of the present invention, the obtaining the third position of the center of the carrier with respect to the rotation center of the link comprises:
and measuring and acquiring the distance between the center of the bearing platform and the rotation center of the connecting rod through a measuring instrument, and acquiring a third position of the center of the bearing platform relative to the rotation center of the connecting rod according to the distance.
According to an embodiment of the present invention, the obtaining a fourth position of the center of the to-be-measured silicon wafer relative to the center of the carrying table includes:
acquiring an outermost circle image of the silicon wafer to be detected;
fitting a circle center according to the positions of more than three edge points on the outermost circle of image;
acquiring a deflection angle of a silicon chip gap in the silicon chip to be detected relative to a silicon chip gap of a reference silicon chip;
and acquiring a fourth position of the center of the silicon wafer to be tested relative to the center of the bearing table according to the fitting circle center and the deviation angle.
According to the silicon wafer back detection equipment and the silicon wafer back detection method provided by the embodiment of the invention, the equipment comprises: the spiral guide rail seat, the connecting rod and the sliding block; the spiral guide rail seat is provided with first grooves which are spirally arranged from the center to the edge, one end of the connecting rod is connected to the center of the spiral guide rail seat through a rotating shaft, the other end of the connecting rod makes circular motion around the center of the spiral guide rail seat, the sliding block is sleeved on the connecting rod, one side, close to the first grooves, of the sliding block is provided with first rollers, one side, far away from the first grooves, of the sliding block is provided with a visual detection device, and at least part of the first rollers are arranged in the first grooves; the driving device is connected with the rotating shaft and used for driving the connecting rod to rotate so as to drive the first roller to move along the first groove and simultaneously drive the sliding block to slide on the connecting rod, so that the moving track of the visual detection device is a spiral track; the bearing platform is used for bearing a silicon wafer to be detected, and the silicon wafer to be detected faces to the view field direction of the visual detection device, so that the detection precision can be ensured on the basis of simplifying the structure of the spiral scanning equipment.
Drawings
FIG. 1 is a prior art scanning trajectory;
FIG. 2 is another prior art scanning trajectory;
FIG. 3 is yet another prior art scanning trajectory;
FIG. 4 is a schematic structural diagram of a silicon wafer back inspection apparatus according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a spiral rail seat in a silicon wafer back inspection apparatus according to an embodiment of the present invention;
FIG. 6 is a top view of a spiral rail seat in a silicon wafer back inspection apparatus according to an embodiment of the present invention;
FIG. 7 is a cross-sectional view of FIG. 6 taken along direction AA;
FIG. 8 is a top view of a spiral guide rail seat in a silicon wafer back inspection apparatus according to an embodiment of the present invention;
FIG. 9 is a schematic view of a pitch of a spiral guide rail seat in a silicon wafer back inspection device according to an embodiment of the present invention;
FIG. 10 is a flowchart of a method for back inspection of a silicon wafer according to an embodiment of the present invention;
fig. 11 is a schematic coordinate diagram of an equation of a track curve obtained in the silicon wafer back inspection method according to the embodiment of the present invention;
fig. 12 is a schematic structural diagram of a middle reference silicon wafer in the silicon wafer back inspection method according to the embodiment of the present invention;
fig. 13 is a schematic diagram illustrating a middle spiral scanning path planning of a silicon wafer back inspection method according to an embodiment of the present invention;
fig. 14 is a schematic diagram illustrating defect location determination in the silicon wafer back inspection method according to the embodiment of the invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 4 is a schematic structural diagram of a silicon wafer back inspection apparatus according to an embodiment of the present invention. As shown in fig. 4 to 7, the silicon wafer back inspection apparatus 100 includes: a spiral guide rail seat 101, a connecting rod 102, a slide block 103, a driving device 104 and a bearing platform 105;
the spiral guide rail seat 101 is provided with first grooves 106 which are spirally arranged from the center to the edge, one end of the connecting rod 102 is connected to the center of the spiral guide rail seat 101 through a rotating shaft 111, the other end of the connecting rod 102 makes circular motion around the center of the spiral guide rail seat 101, the sliding block 103 is sleeved on the connecting rod 102, one side, close to the first groove 106, of the sliding block 103 is provided with a first roller 107, one side, far away from the first groove 106, of the sliding block 103 is provided with a visual detection device 108, and at least part of the first roller 107 is arranged in the first groove 106; the driving device 104 is connected to the rotating shaft 111, and is configured to drive the connecting rod 102 to rotate, so as to drive the first roller 107 to move along the first groove 106, and simultaneously drive the sliding block 103 to slide on the connecting rod 102, so that a moving track of the visual inspection device 108 is a spiral track; the bearing table 105 is used for bearing a silicon wafer 109 to be tested, and the silicon wafer 109 to be tested faces the visual field direction of the visual detection device 108.
It should be noted that the driving device 104 may be a driving motor, and may also be other driving devices that can realize the rotation of the connecting rod 102 in the field, and the invention is not limited in this respect. The susceptor 105 may be an inverted platform support (as shown in fig. 4) having three support claws, the edge end point of each support claw forms a circle, the three support claws are used for grasping the edge of the silicon wafer 109 to be tested to fix the silicon wafer 109 to be tested, the susceptor 105 is kept still during the testing process, and the center of the susceptor 105 is overlapped with the rotation center of the connecting rod 102 as much as possible.
It is understood that one end of the connecting rod 102 where the rotating shaft 111 is disposed is located at the starting end of the first groove 106 and coincides with the center of the screw guide holder 101. The spiral guide holder 101 is a circular disc, the first groove 106 is a spiral groove cut in the circular disc, and the first roller 107 rolls along the bottom of the spiral groove.
Based on this, the driving device 104 drives the rotating shaft 111 to drive the connecting rod 102 to rotate, so that the first roller 107 disposed on one side of the slider 103 on the connecting rod 102, which is adjacent to the first groove 106, rolls in the first groove 106 to drive the slider 103 to slide on the connecting rod 102, so that the moving track of the visual inspection device 108 disposed on one side of the slider 103, which is away from the first groove 106, is a spiral track, so as to spirally scan the silicon wafer 109 to be tested, which is disposed facing the visual field direction of the visual inspection device 108, the silicon wafer inspection apparatus 100 can drive the connecting rod 102 to rotate only through the rotating shaft 111 and the driving device 104 disposed on one end of the connecting rod 102, and combines with the spiral guide seat 101, so as to complete the spiral scanning of the visual inspection device 108 on the silicon wafer 109 to be tested, i.e., the single rotating motion is changed into the spiral motion through the spiral guide seat 101 and the slider 103, thereby reducing the complexity of the apparatus, the difficulty of realizing spiral scanning detection is reduced, and the detection efficiency is improved.
According to an embodiment of the present invention, as shown in fig. 4, the silicon wafer back inspection apparatus 100 further includes: the second roller 110, the second roller 110 is connected with the other end of the connecting rod 102, the second roller 110 rolls around the first rolling shaft 113 and contacts with the outer wall of the spiral guide rail seat 101, the first rolling shaft 113 is arranged in parallel with the central shaft of the spiral guide rail seat 101, and the first rolling shaft 113 makes a circular motion with the center of the spiral guide rail seat 101 as the center of a circle.
In this embodiment, when one end of the connecting rod 102 rotates at the center of the spiral guide rail seat 101, the other end of the connecting rod 102 is provided with the second roller 110, so that the stability of the connecting rod 102 can be improved, the connecting rod 102 is prevented from shaking, and the image acquisition of the silicon wafer 109 to be detected by the vision detection device 108 is not accurate, so that the accuracy of detection is improved by the second roller 110. While the second roller 110 in this embodiment rolls against the outer wall of the screw guide 101, the stability of the connecting rod 102 can be maintained by the friction between the outer wall of the screw guide 101 and the second roller 110. In addition, the structural design of the screw guide holder 101 is simplified.
According to an embodiment of the present invention, as shown in fig. 8, the silicon wafer back inspection apparatus 100 further includes: a second roller 110, the second roller 110 is connected to the other end of the connecting rod 102, the second roller 110 rolls around a second rolling axis, and the second rolling axis (not shown in the figure) is arranged along the radial direction of the track of the other end of the connecting rod 102 making a circular motion;
the outer edge of the spiral guide rail seat 101 is provided with a circular second groove 112, and the second roller 110 rolls in contact with the groove bottom of the second groove 112.
Similarly, in this embodiment, when one end of the connecting rod 102 rotates at the center of the spiral guide rail seat 101, the other end of the connecting rod 102 is provided with the second roller 110, so that the stability of the connecting rod 102 can be improved, and the connecting rod 102 is prevented from shaking, which causes the inaccurate image acquisition of the silicon wafer 109 to be detected by the vision detection device 108, and thus the improvement of the detection precision is facilitated through the second roller 110.
According to an embodiment of the present invention, as shown in fig. 9, the pitch d1 of the first groove 106 of the screw arrangement on the screw guide 101 is smaller than or equal to the distance d2 of the visual field of the visual inspection device 108 in the direction of the pitch.
That is, when the visual inspection device 108 scans the silicon wafer 109 to be inspected spirally, the effective field range of the visual inspection device 108 along the pitch direction needs to cover the pitch range, so that any position on the silicon wafer 109 to be inspected is not missed. When the thread pitch d1 is equal to the viewing field distance d2 of the visual detection device 108 along the thread pitch direction, the visual detection device 108 can just detect any position on the silicon wafer 109 to be detected without missing, the image collection of the silicon wafer 109 to be detected between adjacent thread pitches is not repeated, and the difficulty of image processing in the later period is reduced.
According to one embodiment of the invention, the visual inspection device 108 is a CCD camera or a CMOS camera.
In the silicon wafer back inspection apparatus 100, although the center of the susceptor 105, the center of the silicon wafer 109 to be inspected, and the rotation center of the link 102 are overlapped as much as possible, in actual operation, the above center points always deviate from each other, so that the visual inspection device 108 cannot accurately inspect the silicon wafer (the position of the defect relative to the center of the silicon wafer to be inspected always deviates). Therefore, the embodiment of the invention provides a silicon wafer back inspection method for correcting, so that the detection result is more accurate (the position of the defect relative to the center of the silicon wafer to be detected is the real position of the defect on the silicon wafer to be detected). The silicon wafer back inspection method proposed by the embodiment of the invention is described in detail below.
Fig. 10 is a flowchart of a silicon wafer back inspection method according to an embodiment of the present invention. The method is implemented based on the silicon wafer back inspection equipment, as shown in fig. 10, and comprises the following steps:
s101, acquiring a track curve equation of the center of the visual detection device in a data fitting mode;
according to one embodiment of the invention, the trajectory profile equation satisfies the following formula:
Figure BDA0003482219570000091
wherein r represents the distance between the upper point of the trajectory curve and the connecting line of the rotation center points of the connecting rods, as shown in FIG. 11, and r0Denotes a distance from an edge of the screw guide holder to a rotation center of the link, θ denotes an angle of rotation of the link, Δ d denotes a pitch of the first groove, c0，c1，c2Error term coefficients are expressed, and (x, y) represents position coordinates describing a point on the trajectory curve under a rectangular coordinate system defined as: and taking the rotation center of the connecting rod as an origin, taking a connecting line of the starting point and the end point of the first groove as an X axis, and taking the Y axis direction to be vertical to the X axis, wherein the rotation center of the connecting rod is superposed with the starting point of the first groove.
According to one embodiment of the invention, the error term coefficient c0，c1，c2Satisfies the following conditions:
Figure BDA0003482219570000101
wherein, thetaiIndicating the rotation angle of the connecting rod corresponding to the ith mark theoretically, (x)i,yi) Indicating the actual position of the alignment of the ith mark, and a plurality of marks are uniformly distributed on the reference silicon wafer.
It should be noted that, as shown in fig. 12, the spiral trajectory curve equation is obtained by detecting a reference silicon wafer, first, a plurality of marks (for example, "+" marks in the drawing) are marked on the reference silicon wafer, the plurality of marks are uniformly distributed on the reference silicon wafer, and the positions of the marks marked in advance are marked with respect to the center of the reference silicon wafer, that is, the rotation angle of the link corresponding to each mark on the reference silicon wafer can be marked. Wherein the plurality of marks is at least three.
Then, after the marks are marked, the reference silicon wafer is placed on silicon wafer back inspection equipment, the positions of a plurality of actual points of the reference silicon wafer are acquired in a spiral mode through a visual inspection device, a spiral track curve equation can be obtained through fitting according to a plurality of groups of actual result data, then, an error term coefficient can be calculated according to actual result data and theoretical data of the marks, and therefore the finally obtained spiral track curve equation is a track curve equation carrying errors between an actual spiral track and a reference spiral track.
The central point of each image collected by the visual detection device is located at the center of the visual field of the visual detection device, so that the position of any other point in the image can be obtained relative to the position of the visual field center, and the position of the visual field center relative to the rotation center of the connecting rod can be obtained through a spiral track curve equation, so that the position of any other point in the image can be obtained relative to the position of the rotation center of the connecting rod.
S102, acquiring any image acquired by a visual detection device;
s103, identifying a first position of a defect in the image under a coordinate system of the visual inspection device;
s104, acquiring a second position of the center of the visual detection device relative to the rotation center of the connecting rod according to a track curve equation;
it should be noted that, in step S101, the reference silicon wafer is obtained by detecting the reference silicon wafer, after step S102, the reference silicon wafer needs to be replaced by the silicon wafer to be tested, after the silicon wafer to be tested is replaced, the photographing positions are sequentially planned according to the rotation angle (as shown in fig. 13), the planning principle is that the camera can uniformly cover the whole silicon wafer, and the photographing frequency is minimum, the visual inspection device acquires an image of a certain position on the silicon wafer to be tested, the defect in the image can be identified through an image identification algorithm, the first position of the defect in the coordinate system of the visual inspection device can be known, and the position of the defect relative to the rotation center of the connecting rod can be known according to the trajectory curve equation, so that the position of the defect in the image is transferred to the coordinate system where the spiral guide rail seat is located.
S105, acquiring a third position of the center of the bearing table relative to the rotation center of the connecting rod;
according to one embodiment of the invention, obtaining the third position of the center of the carrier stage relative to the center of rotation of the link comprises:
and measuring and acquiring the distance of the center of the bearing platform relative to the rotation center of the connecting rod through the measuring instrument, and acquiring a third position of the center of the bearing platform relative to the rotation center of the connecting rod according to the distance.
The center of the bearing platform is theoretically overlapped with the rotation center of the connecting rod, but the center of the bearing platform is not overlapped with the rotation center of the connecting rod possibly due to equipment assembly problems, and further correction is needed.
When the equipment is assembled, the distance between the center of the bearing table and the rotation center of the connecting rod can be measured through a measuring instrument (such as a distance measuring tool like a laser ruler or an interferometer), so that the position coordinate of the rotation center of the connecting rod can be transferred to the coordinate system of the bearing table, and further, the position of the defect can be transferred to the coordinate system of the bearing table.
S106, acquiring a fourth position of the center of the silicon wafer to be tested relative to the center of the bearing table;
according to an embodiment of the present invention, the obtaining the fourth position of the center of the silicon wafer to be tested relative to the center of the bearing table includes:
acquiring an outermost circle image of a silicon wafer to be detected;
fitting a circle center according to the positions of more than three edge points on the outermost circle of image;
acquiring a deflection angle of a silicon chip gap in a silicon chip to be detected relative to a silicon chip gap of a reference silicon chip;
and acquiring a fourth position of the center of the silicon wafer to be measured relative to the center of the bearing table according to the fitted circle center and the deviation angle.
It should be noted that the center of the silicon wafer to be measured should theoretically coincide with the center of the susceptor, but the center of the silicon wafer to be measured may not coincide with the center of the susceptor because the silicon wafer to be measured may not be placed correctly each time the silicon wafer to be measured is placed, and thus, correction is required. Firstly, acquiring a fitting circle center of a silicon wafer to be detected, and then acquiring the distance between the fitting circle center and the center of the bearing table. In addition, when the silicon wafer to be detected is placed, the silicon wafer to be detected can have a deflection angle relative to the reference silicon wafer, so that the rotation angle of the positioning coordinate system on the silicon wafer to be detected relative to the positioning coordinate system of the reference silicon wafer can be obtained through the deflection angle of the silicon wafer notch on the silicon wafer to be detected and the silicon wafer notch of the reference silicon wafer, therefore, based on the distance and the deflection angle between the fitting circle center and the center of the bearing table, the center position of the bearing table can be transferred to the position under the coordinate system of the silicon wafer to be detected, and further, the position of the defect can be transferred to the position under the coordinate system of the silicon wafer to be detected.
And S107, acquiring the position of the defect relative to the center of the silicon wafer to be detected according to the first position, the second position, the third position and the fourth position.
Specifically, as shown in fig. 14, the images are taken circle by circle along the planned path, the pixel position of the defect in the image is calculated by using an image recognition algorithm, and the physical position posmycs of the defect relative to the camera center O2 is obtained through conversion.
And calculating the position V2 of the actual camera center relative to the rotation center O1 of the connecting rod during photographing according to the spiral track curve equation by the corresponding photographing rotation angle of the picture, wherein the rotation center O1 of the connecting rod is in a static state relative to the center O3 of the bearing table, and the position relation is V1, so that the position Pospycs + V1+ V2 of the defect relative to the bearing table can be obtained.
Through recognition of the outermost circle of the silicon wafer, the position of more than three edge points is fitted with the center O4, so that the offset error of the center O4 of the silicon wafer to be measured relative to the bearing table is obtained, and the turning angle of the Notch (silicon wafer gap) relative to the ideal upper wafer position (without error) is found to obtain the deviation error of the silicon wafer to be measured, so that the relation V0 of the silicon wafer to be measured relative to the bearing table can be obtained.
And then the position relation of the defect relative to the circle center O4 of the silicon wafer to be detected can be calculated, so that the purposes of correcting errors on line and obtaining the accurate position of the defect on the back of the silicon wafer to be detected are achieved, and the calculation formula is as follows: posgwcs ═ posmycs + V0+ V1+ V2.
Therefore, by designing the spiral guide rail type structure, the trajectory control of the spiral motion is ensured through the pure mechanism motion relation, the control difficulty is reduced, meanwhile, in order to avoid errors caused by manufacturing and assembling of mechanical equipment, a method combining offline calibration and online correction is used, the detection precision is ensured, and the aim of realizing high-precision spiral motion detection by controlling a single rotating shaft is fulfilled.
In summary, according to the silicon wafer back inspection apparatus and the back inspection method provided in the embodiments of the present invention, the apparatus includes: the spiral guide rail seat, the connecting rod and the sliding block; the spiral guide rail seat is provided with first grooves which are spirally arranged from the center to the edge, one end of the connecting rod is connected to the center of the spiral guide rail seat through a rotating shaft, the other end of the connecting rod makes circular motion around the center of the spiral guide rail seat, the sliding block is sleeved on the connecting rod, one side, close to the first grooves, of the sliding block is provided with first rollers, one side, far away from the first grooves, of the sliding block is provided with a visual detection device, and at least part of the first rollers are arranged in the first grooves; the driving device is connected with the rotating shaft and used for driving the connecting rod to rotate so as to drive the first roller to move along the first groove and simultaneously drive the sliding block to slide on the connecting rod, so that the moving track of the visual detection device is a spiral track; the bearing platform is used for bearing a silicon wafer to be detected, and the silicon wafer to be detected faces back to the view field direction of the visual detection device, so that the detection precision can be ensured on the basis of simplifying the structure of the spiral scanning equipment.
It is to be noted that the foregoing description is only exemplary of the invention and that the principles of the technology may be employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (10)

1. A silicon wafer back inspection device is characterized by comprising: the spiral guide rail seat, the connecting rod and the sliding block;
the spiral guide rail seat is provided with first grooves which are spirally arranged from the center to the edge, one end of the connecting rod is connected to the center of the spiral guide rail seat through a rotating shaft, the other end of the connecting rod makes circular motion around the center of the spiral guide rail seat, the sliding block is sleeved on the connecting rod, one side, close to the first groove, of the sliding block is provided with a first roller, one side, far away from the first groove, of the sliding block is provided with a visual detection device, and at least part of the first roller is arranged in the first groove;
the driving device is connected with the rotating shaft and used for driving the connecting rod to rotate so as to drive the first roller to move along the first groove and simultaneously drive the sliding block to slide on the connecting rod, so that the moving track of the visual detection device is a spiral track;
and the bearing table is used for bearing a silicon wafer to be detected, and the silicon wafer to be detected faces to the visual field direction of the visual detection device.
2. The silicon wafer back inspection apparatus of claim 1, further comprising: the second roller is connected with the other end of the connecting rod, the second roller winds a first rolling shaft and contacts the outer wall of the spiral guide rail seat to roll, the first rolling shaft is arranged in parallel with the central shaft of the spiral guide rail seat, and the first rolling shaft takes the center of the spiral guide rail seat as the circle center to perform circular motion.
3. The silicon wafer back inspection apparatus of claim 1, further comprising: the second roller is connected with the other end of the connecting rod, rolls around a second rolling shaft, and the second rolling shaft is arranged along the radial direction of the track of the other end of the connecting rod which does circular motion;
and a circular second groove is formed in the outer edge of the spiral guide rail seat, and the second roller is in contact with the groove bottom of the second groove and rolls.
4. The silicon wafer back inspection apparatus according to claim 1, wherein a pitch of the first groove of the screw arrangement on the screw guide base is smaller than or equal to a visual field distance of the visual inspection device along the pitch direction.
5. The silicon wafer back inspection device of claim 1, wherein the visual inspection device is a CCD camera or a CMOS camera.
6. A silicon wafer back inspection method, which is realized based on the silicon wafer back inspection equipment according to any one of claims 1 to 5, and comprises the following steps:
acquiring a track curve equation of the center of the visual detection device in a data fitting mode;
acquiring any one image acquired by the visual detection device;
identifying a first location of a defect in the image under the visual inspection device coordinate system;
according to the track curve equation, acquiring a second position of the center of the visual detection device relative to the rotation center of the connecting rod;
acquiring a third position of the center of the bearing table relative to the rotation center of the connecting rod;
acquiring a fourth position of the center of the silicon wafer to be tested relative to the center of the bearing table;
and acquiring the position of the defect relative to the center of the silicon wafer to be detected according to the first position, the second position, the third position and the fourth position.
7. The silicon wafer back inspection method according to claim 6, wherein the trajectory curve equation satisfies the following formula:
Figure FDA0003482219560000021
wherein r represents the distance between the upper point of the trajectory curve and the connecting line of the rotation center points of the connecting rods, and r0Represents the distance from the edge of the spiral guide rail seat to the rotation center of the connecting rod, theta represents the rotation angle of the connecting rod, and delta d isShowing the pitch of said first groove, c0，c1，c2Representing error term coefficients, (x, y) representing position coordinates describing a point on the trajectory curve under a rectangular coordinate system defined as: and taking the rotation center of the connecting rod as an origin, taking a connecting line of the starting point and the end point of the first groove as an X axis, wherein the Y axis direction is vertical to the X axis, and the rotation center of the connecting rod is coincided with the starting point of the first groove.
8. The silicon wafer back inspection method as claimed in claim 7, wherein the error term coefficient c0，c1，c2Satisfies the following conditions:
Figure FDA0003482219560000031
wherein, thetaiIndicating the rotation angle of the connecting rod corresponding to the ith mark theoretically, (x)i,yi) And the actual position of the aligned ith mark is shown, and a plurality of marks are uniformly distributed on the reference silicon wafer.
9. The silicon wafer back inspection method according to claim 6, wherein the obtaining of the third position of the center of the susceptor relative to the rotation center of the link comprises:
and measuring and acquiring the distance between the center of the bearing platform and the rotation center of the connecting rod through a measuring instrument, and acquiring a third position of the center of the bearing platform relative to the rotation center of the connecting rod according to the distance.
10. The silicon wafer back inspection method according to claim 6, wherein the acquiring the fourth position of the center of the silicon wafer to be tested relative to the center of the bearing table comprises:
acquiring an outermost circle image of the silicon wafer to be detected;
fitting a circle center according to the positions of more than three edge points on the outermost circle of image;
acquiring a deflection angle of a silicon chip gap in the silicon chip to be detected relative to a silicon chip gap of a reference silicon chip;
and acquiring a fourth position of the center of the silicon wafer to be tested relative to the center of the bearing table according to the fitting circle center and the deviation angle.
CN202210071123.9A 2022-01-21 2022-01-21 Silicon wafer back inspection equipment and back inspection method Pending CN114527142A (en)

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CN202210071123.9A CN114527142A (en) 2022-01-21 2022-01-21 Silicon wafer back inspection equipment and back inspection method

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