CN112325784A - Warpage detection method - Google Patents
Warpage detection method Download PDFInfo
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- CN112325784A CN112325784A CN202011038861.0A CN202011038861A CN112325784A CN 112325784 A CN112325784 A CN 112325784A CN 202011038861 A CN202011038861 A CN 202011038861A CN 112325784 A CN112325784 A CN 112325784A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/161—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/2441—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures using interferometry
Abstract
A warpage detection method detects the surface of an object to be detected through warpage detection equipment. The method comprises the following steps: the interference assembly and the carrier are driven to move relative to each other along the Z-axis direction, so that a plurality of groups of interference fringes corresponding to the surface are output in real time, wherein the plane of the carrier forms an acute angle relative to the horizontal plane; calculating a plurality of fringe contrast values of a plurality of groups of interference fringes and finding out the initial Z-axis position of the interference assembly; driving an interference objective lens of the interference assembly to move along the Z-axis direction from the initial Z-axis position for outputting the multiple groups of interference fringes corresponding to multiple surface areas in real time; and acquiring a plurality of displacement data of the interference objective lens, and calculating the warping degree data of the object to be measured.
Description
Technical Field
The invention relates to a warpage detection method, in particular to a warpage detection method for detecting the warpage of the surface of an object to be detected.
Background
With the development of image technology, the functions of electronic products such as mobile phones, notebook computers, tablet computers and the like are continuously expanded and increased, wherein the camera function is one of the key points of the user for choosing and purchasing, and the requirements of the user on the camera module are higher and higher. Based on the complexity of the manufacturing process of the camera module, some optical sensor chips are difficult to avoid warping and have poor flatness, so that the imaging quality is affected.
In the industry, the flatness of the chip substrate is usually checked and controlled in the front-end manufacturing process for shipment, however, the chip substrate is likely to deform secondarily in the rear-end packaging manufacturing process based on factors such as glue shrinkage and external force, and the image resolution of the camera module needs to be reflected in the rear-end of the manufacturing process, which brings the trouble of 'high-grade' lens model selection to enterprises, cannot give full play to the limit of the lens resolution, and virtually increases the cost of the enterprises. In addition, in the poor product detected in the back-end process, the warpage inspection needs to be performed on the back-reflow front-end after disassembly, so that the labor hour of personnel is increased, and the disassembly may cause secondary deformation to form interference of analysis.
Disclosure of Invention
The inventor recognizes that the conventional warpage detection method is a structured light projection method, and when detecting an optical sensor chip in a substrate, factors such as a specular reflection property of a chip surface and a dark color of a substrate material generally cause an actual detection result to have low contrast and poor detection accuracy, thereby causing troubles in the detection application of the optical sensor chip. In view of the above, some embodiments of the present invention provide a warpage detection method, and in particular, a warpage detection method based on a white light interferometer.
According to some embodiments of the present invention, a warpage detection method detects a surface of an object to be detected, the surface having a plurality of surface areas with different heights, by a warpage detection apparatus, the warpage detection apparatus includes an interference sensing device, a calculation device, and a stage for holding the object to be detected, the interference sensing device includes a white light source module, a light splitting element, an interference module, and a photosensitive module. The warpage detection method includes: the interference assembly and the carrier are driven to move relative to each other along the Z-axis direction, so that the photosensitive assembly outputs a plurality of groups of interference fringes corresponding to the surface, wherein the Z-axis direction is vertical to the horizontal plane, the carrier is provided with a carrier plane, and the carrier plane forms an acute angle relative to the horizontal plane; the calculation device calculates a plurality of fringe contrast values of the plurality of groups of interference fringes and finds out the initial Z-axis position of the interference component corresponding to the interference fringe with the maximum fringe contrast value; driving an interference objective lens of the interference assembly to move along the Z-axis direction from the initial Z-axis position, and enabling the photosensitive assembly to output a plurality of groups of interference fringes corresponding to a plurality of surface areas; and the arithmetic device acquires a plurality of displacement data corresponding to a plurality of zero optical path positions of the interference objective lens and the plurality of surface areas so as to calculate the warping degree data of the object to be measured.
According to some embodiments of the present invention, the warpage detection method further comprises: the warpage detection equipment drives the plane of the carrying platform to rotate to an acute angle relative to the horizontal plane through the rotating motor.
According to some embodiments of the present invention, the acute angle between the plane of the carrier and the horizontal plane ranges from greater than 0 degrees to less than or equal to 0.6 degrees.
According to some embodiments of the present invention, before the step of driving the interference element to move between the plurality of Z-axis positions in the Z-axis direction, the method further comprises: and setting the module height corresponding to the object to be detected, and driving the interference assembly to a preset position corresponding to the module height.
According to some embodiments of the present invention, before the step of driving the interference element to move between the plurality of Z-axis positions in the Z-axis direction, the method further comprises: the interference component and the carrier are driven to move relative to each other along the Z-axis direction, so that the photosensitive component outputs a plurality of groups of correction interference fringes corresponding to the plane of the carrier; the calculation device calculates a plurality of correction fringe contrast values of a plurality of groups of correction interference fringes and finds out a correction Z-axis position of the interference component corresponding to the correction interference fringe with the maximum correction fringe contrast value; driving an interference objective lens of the interference assembly to move along the Z-axis direction from the correction Z-axis position, so that the photosensitive assembly outputs a plurality of groups of correction interference fringes corresponding to a plurality of platform plane areas; and the arithmetic device acquires a plurality of displacement data of the interference objective lens at a plurality of Z-axis positions, acquires a plurality of correction displacement data corresponding to the interference objective lens and a plurality of zero optical path correction positions of a plurality of platform plane areas, and calculates the warping degree data of the object to be measured according to the plurality of displacement data and the plurality of correction displacement data.
According to some embodiments of the present invention, before the step of driving the interference component and the stage to move relative to each other along the Z-axis direction, the method further comprises: and driving the interference component to a correction height position corresponding to the plane of the carrier.
Therefore, according to some embodiments, the warpage detection method utilizes an acute angle formed by the plane of the stage relative to the horizontal plane to generate obvious interference fringes, automatically detects zero optical path positions of different surface heights of the object to be detected, identifies the optimal interference fringe position and feeds back displacement information, and accordingly obtains original warpage data.
The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.
Drawings
FIG. 1 is a side view of a warp detection apparatus according to some embodiments of the present invention;
FIG. 2 is a schematic perspective view of the object to be measured placed on the stage in the embodiment shown in FIG. 1;
FIG. 3 is an image of an interference fringe exhibited by the DUT shown in the embodiment of FIG. 1;
FIG. 4 is an enlarged, partial side view schematic of an imaging mechanism according to some embodiments of the invention;
fig. 5 is a perspective view of a carrier according to some embodiments of the invention;
FIG. 6 is a flow chart illustrating a warpage detection method according to some embodiments of the present invention;
FIG. 7 is a flowchart illustrating a calibration process of a warpage detection method according to some embodiments of the present invention.
Wherein the reference numerals
α: acute angle
Beta: angle of incidence
A: test object
A1: surface of
A10, a11, a12, a13, a 14: surface area
B: horizontal plane
C: optical axis
H: height difference
S1-S4, S01-S04: step (ii) of
R0-R4: sensing region
1: interference sensing device
10: white light source assembly
100: light emitting element
102: collimating lens
12: light splitting element
14: interference assembly
140: interference objective
142: interference light splitting element
144: reflecting mirror
146: phase shift assembly
16: photosensitive assembly
18: driving motor
2: calculation device
3: carrying platform
30: platform plane
32: mobile motor
34: rotating electrical machine
Detailed Description
In the description of the specification, numerous specific details are set forth in order to provide a more thorough understanding of the invention; however, the present invention may be practiced without some or all of these specific details. The same or similar elements in the drawings will be denoted by the same or similar symbols. It is particularly noted that the drawings are for illustrative purposes only and do not represent actual sizes or quantities of elements, and that some of the details may not be shown in full in order to simplify the drawings.
The invention will be described in detail with reference to the following drawings, which are provided for illustration purposes and the like:
FIG. 1 is a side view of a warp detection apparatus according to some embodiments of the present invention. Fig. 2 is a schematic perspective view of the object to be measured placed on the carrier in the embodiment shown in fig. 1. Fig. 3 is an image of interference fringes exhibited by the object to be measured according to the embodiment shown in fig. 1.
Referring to fig. 1, a warp detection apparatus according to some embodiments of the present invention includes an interference sensing device 1, a calculation device 2, and a stage 3, wherein the warp detection apparatus detects a warping degree of a1 surface of an object a to be detected. In an exemplary embodiment, the object a is a light sensor chip for a camera module, but is not limited thereto.
In some embodiments, the interference sensing device 1 includes a white light source assembly 10, a light splitting element 12, an interference assembly 14, a photosensitive assembly 16 and a driving motor 18. The white light source assembly 10 includes a light emitting element 100 and a collimating lens 102, where the white light source assembly 10 emits parallel light rays with white light wavelength to the light splitting element 12, but is not limited thereto; in other embodiments, the white light source assembly 10 mixes light with a plurality of laser elements having different frequency bands to generate parallel light rays with low coherence without disposing optical components such as an aperture stop, a field stop, or the collimating lens 102.
The light splitting element 12 has a first light emitting surface facing the white light source assembly 10, a second light emitting surface facing the interference assembly 14, and a first light incident surface connected to the first light emitting surface and the second light emitting surface, wherein the second light emitting surface faces the photosensitive assembly 16. Here, the light splitting element 12 receives the parallel light through the first light incident surface and outputs part of the parallel light through the first light emitting surface.
The interference component 14 includes an interference objective 140, an interference beam splitter 142, a mirror 144, and a phase shift component 146. The interference objective 140 is located between the first light-emitting surface of the light splitting element 12 and the interference light splitting element 142, where the interference objective 140 receives the part of the parallel light from the light splitting element 12 and outputs the working light to the interference light splitting element 142. In some embodiments, interference objective 140 is a Mirau objective, but is not so limited.
The interference beam splitter 142 includes a second light incident surface and a third light emitting surface opposite to the second light incident surface, wherein the second light incident surface faces the interference objective lens 140, and the third light emitting surface faces the stage 3. Here, the interference beam splitter 142 receives the working light from the interference objective 140 through the second light incident surface, outputs the reference beam to the interference objective 140 through the second light incident surface, and outputs the sample beam toward the stage 3 through the third light emergent surface to irradiate the object a to be measured.
The reflector 144 is disposed between the interference objective 140 and the interference beam splitter 142, where the reflector 144 receives the working light from the interference objective 140 and outputs the reference beam to the second light incident surface of the interference beam splitter 142.
The phase shift unit 146 is connected to the interference objective 140, wherein the phase shift unit 146 drives the interference objective 140 to move along the Z-axis direction according to the adjustment signal, and outputs a plurality of displacement data about the interference objective 140.
The photosensitive element 16 faces the second light-emitting surface of the light-splitting element 12, and here, the photosensitive element 16 obtains an interference fringe image generated by mutual interference between the sample beam reflected by the object a to be measured and the reference beam reflected by the reflecting mirror 144, as shown in fig. 3. In some embodiments, the photosensitive component 16 is a Charge-coupled device (CCD), but not limited thereto.
The driving motor 18 is connected to the interference component 14, and the driving motor 18 drives the interference component 14 for the photosensitive component 16 to sense the object a to be detected, but not limited thereto; in other embodiments, the driving motor 18 is connected to the stage 3, and the driving motor 18 drives the stage 3 to drive the object a to be measured, so that the object a to be measured moves relative to the interference assembly 14 for the photosensitive assembly 16 to sense the object a to be measured. In some embodiments, the drive motor 18 is a stepper motor, but is not so limited.
The computing device 2 is electrically connected to the interference sensing device 1, and herein, the computing device 2 outputs an adjustment signal to the phase shifting element 146, receives a plurality of displacement data about the interference objective lens 140 fed back by the phase shifting element 146, and receives the imaging data about the interference fringes transmitted by the photosensitive element 16 for image processing. In some embodiments, the computing device 2 can be implemented by one or more processing elements such as microprocessors, microcontrollers, digital signal processors, microcomputers, central processing units, field programmable gate arrays, programmable logic devices, state machines, logic circuits, analog circuits, digital circuits, and/or any other operating signals (analog and/or digital) based on operational instructions. In some embodiments, the computing device 2 further has a storage unit for storing, for example, but not limited to, imaging data, displacement data, etc., in an exemplary embodiment, the storage unit may be implemented by one or more memories
Referring to fig. 2, which is a schematic perspective view of an object a to be measured being placed on a carrier 3, the carrier 3 has a carrier plane 30, and the carrier plane 30 forms an acute angle α with respect to a horizontal plane B, wherein the horizontal plane B is parallel to an X-Y plane of coordinate axes of a three-dimensional space, and a Z-axis direction is perpendicular to the horizontal plane B. Here, the carrier 3 holds the object a to be detected, so that the interference sensing device 1 senses the surface a1 of the object a to be detected. In some embodiments, the surface a1 of the object a has a plurality of surface regions a10, a11, a12, a13, a14 with different heights, and is a warped surface.
Based on the above, when the interference module 14 and the stage 3 move relative to each other along the Z-axis direction between a plurality of Z-axis positions (i.e., height positions), the photosensitive module 16 senses interference fringes corresponding to each Z-axis position through the spectroscopic element 12 and the interference module 14, and outputs a plurality of sets of interference fringe images of a plurality of sensing Regions (ROIs) R0, R1, R2, R3, and R4 corresponding to a plurality of surface regions a10, a11, a12, a13, and a14 of the surface a 1. In some embodiments, the photosensitive assembly 16 senses the interference fringes corresponding to each Z-axis position through the light splitting element 12 and the interference assembly 14, and outputs multiple sets of interference fringe images of multiple sensing Regions (ROIs) R0, R1, R2, R3 and R4 corresponding to multiple surface regions a10, a11, a12, a13 and a14 of the surface a1 in real time. Here, the interference fringe images obtained by the photosensitive assembly 16 at different Z-axis positions will be changed along with the relative movement between the interference assembly 14 and the stage 3 along the Z-axis direction; meanwhile, the interference fringe image obtained by the photosensitive element 16 will also vary with the magnitude of the acute angle α formed by the stage plane 30 with respect to the horizontal plane B, as described in detail below.
It should be noted that, in some embodiments of the present invention, the acute angle α of the carrier plane 30 with respect to the horizontal plane B should exclude manufacturing tolerances of the warpage detection apparatus, at least an error value of the relative deflection between the interference sensing device 1 and the carrier 3 during the assembly process, which is different from the intentionally introduced acute deflection angle α by human in some embodiments of the present invention. That is, it is assumed that the acute angle α of the stage plane 30 of the conventional white light interferometer with respect to the horizontal plane B is zero, that is, the stage plane 30 and the horizontal plane B are parallel to each other, and the warpage detecting apparatus according to some embodiments of the present invention is intentionally inclined with respect to the horizontal plane B by an acute angle α different from zero.
Referring to fig. 1 and 4 together, under an ideal detection environment, the interference objective 140 is illustrated by using a 20 × magnification, its parfocal distance is 10mm, working distance is 4.7mm, and numerical aperture is 0.3, assuming that the stage plane 30 forms an acute angle α with respect to the horizontal plane B, which is similar to the equal-tilt interference in optics.
If only the sample beam is considered to be of a single wavelength lambda0The monochromatic light of (1) can be known as the interference formula of the conventional monochromatic fringe, where Δ X represents the fringe distance, i.e. the width of the interference fringe, L represents the distance between the light-emitting surface of the interference module 14 and the stage plane 30 (corresponding to the distance between the slit and the light screen in the double-slit interference), and d represents the distance between any two beams of light in the sample beam in the X direction (corresponding to the distance between two slits in the double-slit interference):
Δx＝(L/d)λ0… … … … … … … … … … … … … … … … … … … … … … … type (1)
From the formula (1), when the sample beam has a single wavelength λ0The larger the value, the wider the interference fringes; in addition, the optical path difference Δ L between the bright and dark fringes exhibited by any two light rays in the sample light beam is calculated by the following formula (2), where m is an integer:
as shown in fig. 4, if the height difference H is present between the two light beams, the optical path difference Δ L can also be expressed as the following formula (3):
Δ L ═ H × cos α/cos (α + β) … … … … … … … … … … … … … … … … … … formula (3)
Consider still further that the sample beam contains multiple wavelengths λ1、λ2And taking the position of coherent phase growth, the height difference H ═ m ×. lambda1*cos(α+β)/cosα＝(m+1)λ2Cos (α + β)/cos α, the following relation (4) can be calculated:
m/(m+1)＝λ2/λ1… … … … … … … … … … … … … … … … … … … … … type (4)
Taking the sample beam as an example, the two ends of the white spectrum are red light λ1740nm and violet λ2350nm, where the boundary between the 0 th order and the 1 st order (m is 0 and m is 1) of monochromatic light interference is equivalent to the 1 st order and the 2 nd order (m is 1 and m is 2) of monochromatic light interference, and assuming that the incident angle β of the sample beam with respect to the optical axis C of the interference element 14 is 11.5 degrees, the height difference H between two beams of different wavelengths in the sample beam and the corresponding lateral length I in the interference fringes are respectively expressed by the following formulas (5) and (6):
H＝(m+1)λ2cos (α + β)/cos α ═ 2 × 350nm cos (α +11.5 °)/cos α … formula (5)
H/tan α ═ 2 ═ 350nm ═ cos (α +11.5 °)/sin α … … … … … … … formula (6)
The following table shows the correspondence between the acute angle α, the height difference H and the transverse length I according to equation (6):
[ watch one ]
The inventor has recognized that in the field of a photo sensor chip in a camera module, there is a possibility that at least a part or all of the area of the photo sensor chip is a flat surface, and in this case, the warpage is zero, that is, the aforementioned acute angle α is 0, and in this case, the position of the interference fringe exhibited by the photo sensor chip (i.e., the object a) tends to be infinite, so that the interference fringe imaging is hardly generated.
Specifically, when the surface a1 of the object a has a flat area or a flat surface, which is similar to the flat surface of the stage plane 30 shown in fig. 4 without warpage, the optical calculation formula and the related optical characteristic parameters of the interference fringes of the object a are equivalent to the data listed in the above formulas (1) to (6) and table one. However, according to the above equation (6) and the data in the table, if the acute angle α formed by the stage plane 30 with respect to the horizontal plane B is zero or approaches zero by using the conventional white light interferometer, the position of the interference fringe exhibited by the object a tends to be infinite, so that the value of the lateral length I exceeds the Field of View (FOV) of the photosensitive element 16, and the interference fringe applicable to the operation device 2 cannot be sensed and obtained.
In order to improve the above phenomenon, the warpage detection apparatus according to some embodiments of the present invention intentionally tilts the stage plane 30 with respect to the horizontal plane B to form an acute angle α that is not zero, so as to effectively reduce the value of the lateral length I, so that the position of the interference fringes appearing on the object a to be measured can fall within the field of view (FOV) of the photosensitive assembly 16, thereby obtaining multiple sets of interference fringes that can be used for the arithmetic unit 2 to perform image recognition calculation.
Subsequently, the arithmetic device 2 automatically identifies the zero optical path positions of the surface a1 of the object a to be measured at different surface heights to obtain initial warping degree data, and then performs corresponding arithmetic processing based on the artificially introduced acute angle α that is not zero to obtain the real warping degree data of the object a to be measured. Further, the operation device 2 introduces an evaluation concept of the resolution MTF algorithm, and combines with a calculation method for identifying the 0 th-order interference position to automatically identify the position with the maximum contrast in the interference fringe, that is, the zero optical path position or the 0 th-order interference position. After the computing device 2 obtains the 0 th-order interference positions of the multiple sets of interference fringe images of the different sensing regions R0, R1, R2, R3, and R4, the warpage data of the optical sensor chip (i.e., the object a to be measured) can be obtained, as described in detail below.
According to some embodiments of the present invention, the resolution MTF algorithm first defines 1/20 that the area size of each of the sensing regions R0, R1, R2, R3, and R4 is the original interference image size, as illustrated in fig. 3, the sensing regions R0, R1, R2, R3, and R4 are respectively distributed at the center position and four corner positions of the entire original interference image, and the area sizes of the sensing regions R0, R1, R2, R3, and R4 are the same and are 1/20 that is the original interference image area size.
In an exemplary embodiment, the length of the object a is multiplied by the width to calculate the size of the orthographic projection area of the object a relative to the X-Y plane as 8mm by 6mm or 48mm, taking the object a as an example of the optical sensor chip2Then are correspondingThe sensing regions R0, R1, R2, R3, R4 have an orthographic projection area size of 2.4mm relative to the X-Y plane2. In addition, regarding the optical sensor chip meeting the specification of good products, considering the control height threshold value in the Z-axis direction, for example, but not limited to, 5um, if the height difference H exceeds the control value, it is determined as a defective product, and the area control height threshold values of the sensing areas R0, R1, R2, R3, and R4 with respect to the Z-axis are 0.5um, as shown in the following table two.
[ second table ]
Compared with the detection background of the data in table one, the difference is that the actual surface a1 of the optical sensor chip, i.e. the object a, has a warpage phenomenon, rather than being flat, so that the object a is held on the carrier 3, and the acute angle α formed by the carrier plane 30 relative to the horizontal plane B is changed, so that the correspondence between the acute angle α and the height difference H can be obtained as shown in table three below:
[ third table ]
As can be seen from the above table i, for the interference fringes imaged after introducing the specific acute angle α, the height difference H is significantly demarcated at a position of about 1.45um (corresponding to the above assumed condition parameters of the interference objective 140); from the look-up table three, the height difference H of 1.45um corresponds to the acute angle α being 0.208 °.
In some embodiments, in order to ensure that each sensing region R0, R1, R2, R3, R4 can accommodate the bright and dark positions of the white interference fringes to present a large white interference envelope corresponding to at least one set of bright and dark fringes, the height difference H is 2 times, 1.45 times, 2.9um, and the area control height threshold is 2 times, 1um, the overall height difference H is 1.45 times, 2+0.5 times, 2 times, 3.9um, and accordingly, the lookup table indicates that when the height difference H is 3.9um, the corresponding acute angle α is 0.56 °. Therefore, when the acute angle α between the stage plane 30 and the horizontal plane B is greater than 0 degrees and less than or equal to 0.6 degrees, the arithmetic device 2 can obtain the 0 th-order interference position of the multiple sets of interference fringe images of the different sensing regions R0, R1, R2, R3, and R4, so as to obtain the warpage data of the object a.
Referring to fig. 5, in some embodiments, the carrier 3 has a body structure with a uniform thickness, and the carrier 3 is connected to the moving motor 32 and the rotating motor 34 respectively. Here, movement motor 32 drives stage 3 to move three-dimensionally along axis X, Y, Z, and rotation motor 34 drives stage 3 to rotate with respect to horizontal plane B, so that stage plane 30 is inclined with respect to horizontal plane B at acute angle α different from zero. In some embodiments, the moving motor 32 and the rotating motor 34 are implemented by stepping motors, but not limited thereto.
Referring to fig. 1 to 4 and fig. 6 together, according to some embodiments of the present invention, a warpage detection method detects a surface a1 of an object a to be tested by a warpage detection apparatus, wherein characteristics of the surface a1 of the object a, internal components of the warpage detection apparatus, and connection relationships among the components are as described above, and the warpage detection method includes the following steps. First, the driving motor 18 drives the interference component 14 and the stage 3 to move relative to each other along the Z-axis direction, which is perpendicular to the horizontal plane B, and the stage 3 has a stage plane 30, and the stage plane 30 forms an acute angle α with respect to the horizontal plane B, so that the photosensitive component 16 outputs a plurality of sets of interference fringes corresponding to the surface a1 (step S1). In some embodiments, the driving motor 18 drives the interference assembly 14 and the stage 3 to move relative to each other along the Z-axis direction, so that the photosensitive assembly 16 outputs multiple sets of interference fringes corresponding to the surface a1 in real time.
In some embodiments of step S1, because stage plane 30 is tilted at an acute angle a with respect to horizontal plane B that is not zero, when interference assembly 14 and stage 3 are moved relative to each other between a plurality of Z-axis positions along the Z-axis direction, the photosensitive assembly 16 senses and outputs multiple sets of interference fringe images of multiple sensing regions R0, R1, R2, R3 and R4 corresponding to multiple surface regions A10, A11, A12, A13 and A14 of the surface A1 at different respective Z-axis positions, meanwhile, the interference fringe image obtained by the photosensitive component 16 will change with the size of the acute angle alpha formed by the stage plane 30 relative to the horizontal plane B, therefore, the value of the transverse length I is effectively reduced, so that the position of the interference fringes presented by the object A to be detected can fall into the visual field range of the photosensitive assembly 16, and a plurality of groups of interference fringes for the calculation device 2 to perform image identification calculation are obtained. The related art, advantages, and derivative embodiments have been described above. In some embodiments, the photosensitive assembly 16 senses and outputs sets of interference fringe images of multiple sensing regions R0, R1, R2, R3, R4 corresponding to multiple surface regions a10, a11, a12, a13, a14 of the surface a1 in real time at different respective Z-axis locations.
Next, the arithmetic device 2 calculates a plurality of fringe contrast values of the plurality of sets of interference fringes, and finds an initial Z-axis position of the interference element 14 corresponding to the interference fringe having the largest fringe contrast value (step S2).
In some embodiments of step S2, the fringe sharpness of each sensing region R0, R1, R2, R3, R4 in the original interference image can be measured using fringe contrast values, which are calculated as formula (7) below, where J ismaxRepresenting the brightness value of the bright fringes in the interference fringes, JminThe luminance value of the dark fringe in the interference fringe is represented, K represents a fringe contrast value:
K＝(Jmax-Jmin)/(Jmax+Jmin) … … … … … … … … … … … … … … … type (7)
Taking the sensing regions R0, R1, R2, R3, and R4 shown in fig. 3 as an example, the photosensitive element 16 acquires the maximum amplitude value and the minimum amplitude value in each dashed line frame, and the computing device 2 calculates the corresponding stripe definition values K0, K1, K2, K3, and K4 according to the formula (7). Although fig. 3 shows that the embodiment includes the sensing regions R0 at the center and the sensing regions R1, R2, R3, and R4 at the four corners, the embodiment of the invention does not limit the specific number and distribution positions of the sensing regions R0, R1, R2, R3, and R4.
In some embodiments, the computing device 2 calculates a plurality of fringe contrast values K0 corresponding to a plurality of sets of interference fringes of the central sensing region R0 output by the photosensitive elements 16 at different Z-axis positions, and finds the Z-axis position of the interference element 14 corresponding to the maximum value of the plurality of sets of interference fringes, so as to define the initial Z-axis position of the interference lens 140. Further, the operation device 2 introduces an evaluation concept of the resolution MTF algorithm, and combines with the calculation method for identifying the 0 th-order interference position to automatically identify the position with the maximum contrast in the interference fringes, i.e. the zero optical path position or the 0 th-order interference position, in some embodiments of step S2, only the central sensing region R0 is used as the detection object to find the optimal interference position, i.e. the initial Z-axis position, but not limited thereto. The related art, advantages, and derivative embodiments have been described above. In some embodiments, the computing device 2 outputs multiple sets of interference fringes of the central sensing region R0 at different Z-axis positions in real time according to the photosensitive elements 16.
Next, the phase shift module 146 drives the interference objective 140 of the interference module 14 to move along the Z-axis direction from the initial Z-axis position, so that the photosensitive module 16 outputs a plurality of sets of interference fringes corresponding to the surface regions a10, a11, a12, a13, and a14 (step S3); in some embodiments, the photosensitive assembly 16 outputs sets of interference fringes corresponding to the plurality of surface regions a10, a11, a12, a13, a14 in real time (step S3).
In some embodiments of step S3, phase shift assembly 146 outputs a plurality of displacement data regarding interference objective 140 being located at a plurality of different Z-axis positions in the process of driving interference objective 140 to move in the Z-axis direction. After the computing device 2 obtains the 0 th-order interference positions of the multiple sets of interference fringe images of the different sensing regions R0, R1, R2, R3, R4 corresponding to the multiple surface regions a10, a11, a12, a13, a14, the subsequent step S4 can calculate the warping degree data of the object a. The related art, advantages, and derivative embodiments have been described above. In some embodiments, phase shift assembly 146 outputs a plurality of displacement data in real time with respect to interference objective 140 at a plurality of different Z-axis positions during the driving of interference objective 140 to move along the Z-axis direction.
Subsequently, the arithmetic device 2 acquires a plurality of displacement data corresponding to a plurality of zero optical path positions of the interference objective lens 140 and the plurality of surface regions a10, a11, a12, a13, and a14, so as to calculate the warp data of the object a (step S4).
In some embodiments of step S4, the surface regions a10, a11, a12, a13, a14 display sensing regions R0, R1, R2, R3, R4 in the original interference image, so that the surface regions a10, a11, a12, a13, a14 are associated with sensing regions R0, R1, R2, R3, R4 processed by the calculation device 2 for image calculation, as shown in fig. 3, for example but not limited to: 1 central sensing region R0 and 4 corner sensing regions R1, R2, R3, R4 located at the edges of the image. As mentioned above, when the acute angle α between the stage plane 30 and the horizontal plane B is greater than 0 degrees and less than or equal to 0.6 degrees, the calculation device 2 can obtain the 0 th-order interference position for imaging the multiple sets of interference fringes of different sensing regions R0, R1, R2, R3, and R4, and the related technical contents, advantages, and derivatives thereof are as described above. Therefore, the calculation device 2 can calculate the warping degree data of the object A to be measured, and the calculation formula is as the following formula (8), wherein DmaxRepresenting the maximum value, D, of a plurality of sets of displacement dataminRepresents the minimum of the plurality of sets of displacement data, W represents the warping value:
W＝Dmax–Dmin… … … … … … … … … … … … … … … … … … … … … … … type (8)
According to the above description, the warpage detection method utilizes the acute angle α formed by the stage plane 30 with respect to the horizontal plane B to generate obvious interference fringes, automatically detects the zero optical path positions of the object a to be detected at different surface heights, identifies the optimal interference fringe position and feeds back displacement information, thereby obtaining the original warpage data.
According to some embodiments of the present invention, the acute angle between the plane of the carrier and the horizontal plane ranges from greater than 0 degrees to less than or equal to 0.6 degrees. The related art, effects and advantages are as described above.
Referring to fig. 5, according to some embodiments of the present invention, the warpage detection method further includes: the warp detection apparatus drives the stage plane 30 to rotate to an acute angle α with respect to the horizontal plane B by the rotation motor 34. The related art, effects and advantages are as described above.
According to some embodiments of the present invention, before the step S1 of driving the interference component 14 to move between a plurality of Z-axis positions in the Z-axis direction, the method further includes: the warpage detection apparatus automatically or manually sets a module height corresponding to the object to be measured a, and the driving motor 18 drives the interference assembly 14 to a preset position corresponding to the module height. The size of each mechanism part of the camera module and the position of the optical sensor are known, so that under the condition that the object A to be detected is an optical sensor chip, the coarse focusing process is completed within the range of the preset size, and the detection efficiency is improved.
Referring to fig. 7, a schematic correction flow chart of the warpage detection method according to some embodiments of the invention is shown. According to some embodiments of the present invention, before the step S1 of driving the interference component to move among the plurality of Z-axis positions in the Z-axis direction, the following calibration procedure is further included. First, the driving motor 18 drives the interference component 14 and the stage 3 to move relative to each other along the Z-axis direction, so that the photosensitive component 16 outputs a plurality of sets of correction interference fringes corresponding to the stage plane 30 (step S01); here, the stage 3 does not hold the object a yet, and the photosensitive element 16 directly senses a plurality of sets of correction interference fringes appearing on the stage surface 30. In some embodiments, the driving motor 18 drives the interference component 14 and the stage 3 to move relative to each other along the Z-axis direction, so that the photosensitive component 16 outputs multiple sets of correction interference fringes corresponding to the stage plane 30 in real time (step S01).
In some embodiments of step S01, since the stage plane 30 is inclined relative to the horizontal plane B to form an acute angle α that is not zero, the corrected interference fringes obtained by the photosensitive element 16 will be different with the change of the value of the acute angle α formed by the stage plane 30 relative to the horizontal plane B, thereby effectively reducing the value of the lateral length I, so that the position of the corrected interference fringes presented by the stage plane 30 can fall within the visual field of the photosensitive element 16, and thus obtaining multiple sets of corrected interference fringes that can be used by the operation device 2 for image recognition calculation. The related art and the advantages are similar to the step S1 and the derived embodiments.
Next, the arithmetic device 2 calculates a plurality of correction fringe contrast values of the plurality of sets of correction fringes, and finds a correction Z-axis position of the interference element 14 corresponding to the correction fringe having the maximum correction fringe contrast value (step S02). The related art and the advantages are similar to the step S2 and the derived embodiments.
Next, the phase shift unit 146 drives the interference objective lens 140 of the interference unit 14 to move from the correction Z-axis position along the Z-axis direction, so that the photosensitive unit 16 outputs a plurality of sets of correction interference fringes corresponding to a plurality of stage plane areas (step S03). The related art and the advantages are similar to the step S3 and the derived embodiments. In some embodiments, the phase shift unit 146 drives the interference objective 140 of the interference unit 14 to move along the Z-axis direction from the calibration Z-axis position, so that the photosensitive unit 16 outputs multiple sets of calibration interference fringes corresponding to multiple stage plane areas in real time (step S03).
Subsequently, the arithmetic device 2 obtains a plurality of displacement data of the interference objective lens 140 at a plurality of different Z-axis positions and obtains a plurality of correction displacement data of the interference objective lens 140 corresponding to a plurality of zero optical path correction positions of the plurality of stage plane areas, and calculates the warp degree data of the object a according to the plurality of displacement data and the plurality of correction displacement data (step S04).
In some embodiments of step S04, a plurality of stage plane areas are displayed in the original interference image in the plurality of sensing areas R0, R1, R2, R3, R4, and therefore, the stage plane areas are associated with the plurality of sensing areas R0, R1, R2, R3, R4 processed by the operation device 2 for image calculation, as shown in fig. 3, for example, but not limited to: 1 central sensing region R0 and 4 corner sensing regions R1, R2, R3, R4 located at the edges of the image. As mentioned above, when the acute angle α between the stage plane 30 and the horizontal plane B is greater than 0 degrees and less than or equal to 0.6 degrees, the calculation device 2 can obtain the 0 th-order interference position for imaging the multiple sets of interference fringes of different sensing regions R0, R1, R2, R3, and R4, and the related technical contents, advantages, and derivatives thereof are as described above. Therefore, the calculation device 2 can calculate the warping degree data of the object A to be measured according to the displacement data and the correction displacement data, and the calculation formula is as the following formula (9), wherein D' represents the corrected displacement data set, and DsIndicates that the image is acquired in step S03Correcting the shifted data set, D0Represents the displacement data set, D ', obtained in step S3'maxRepresents the maximum value, D ', in the corrected displacement data set'minRepresents the minimum value in the corrected displacement data set, W' represents the corrected warp value:
D′＝Ds-D0，W′＝D′max-D′min… … … … … … … … … … … … … … type (9)
According to some embodiments of the present invention, before the step S01 of driving the interference component 14 and the stage 3 to move relative to each other along the Z-axis direction, the method further includes: drive motor 18 drives interference assembly 14 to a corrected height position corresponding to stage plane 30. This is because the mechanical dimensions and position of the stage are known, and in the case of direct sensing of the stage plane 30 for correction, the coarse focusing process will be completed within a range of preset dimensions, which helps to improve the correction efficiency.
In summary, according to some embodiments, the warpage detection method utilizes the acute angle α formed by the stage plane 30 relative to the horizontal plane B to generate an obvious interference fringe, so as to effectively reduce the value of the transverse length I, so that the position of the interference fringe presented by the object a to be detected can fall within the visual field range of the photosensitive assembly 16, thereby obtaining multiple sets of interference fringes for the arithmetic unit 2 to perform image recognition calculation, and utilizes the contrast of bright and dark interference fringes to automatically detect the contrast of the fringe pair, so as to identify the zero optical path positions of different surface heights of the surface a2 of the object a to be detected, so as to obtain the initial warping degree data, and based on artificially introducing the acute angle α that is not zero, subsequently perform corresponding arithmetic processing, such as: and correcting the process to obtain the real warping degree data of the object A to be detected. In some embodiments, when the acute angle α between the stage plane 30 and the horizontal plane B is greater than 0 degrees and less than or equal to 0.6 degrees, the arithmetic device 2 can obtain the 0 th-order interference position of the multiple sets of interference fringe images of the different sensing regions R0, R1, R2, R3, and R4, so as to obtain the warping degree data of the object a.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it should be understood that various changes and modifications can be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (6)
1. A warpage detection method, detecting a surface of an object to be detected by a warpage detection apparatus, the surface having a plurality of surface areas with different heights, the warpage detection apparatus comprising an interference sensing device, a calculation device and a stage for holding the object to be detected, the interference sensing device comprising a white light source module, a beam splitting element, an interference module and a photosensitive module, the warpage detection method comprising:
driving the interference assembly and the carrier to move relative to each other along a Z-axis direction, so that the photosensitive assembly outputs a plurality of groups of interference fringes corresponding to the surface, wherein the Z-axis direction is vertical to a horizontal plane, the carrier is provided with a carrier plane, and the carrier plane forms an acute angle relative to the horizontal plane;
the calculation device calculates a plurality of fringe contrast values of the plurality of groups of interference fringes and finds out an initial Z-axis position of the interference component corresponding to the interference fringe with the maximum fringe contrast value;
driving an interference objective lens of the interference assembly to move along the Z-axis direction from the initial Z-axis position, so that the photosensitive assembly outputs the multiple sets of interference fringes corresponding to the multiple surface areas; and
the arithmetic device acquires a plurality of displacement data corresponding to the interference objective lens and a plurality of zero optical path positions of the plurality of surface areas, and accordingly warping degree data of the object to be measured is calculated.
2. The method of claim 1, further comprising:
the warpage detection device drives the platform deck plane to rotate to the acute angle relative to the horizontal plane through a rotating motor.
3. The method of claim 1, wherein the acute angle between the stage plane and the horizontal plane ranges from greater than 0 degrees to less than or equal to 0.6 degrees.
4. The method of claim 1, further comprising, prior to the step of driving the interference assembly to move between a plurality of Z-axis positions in the Z-axis direction:
and setting the module height corresponding to the object to be detected, and driving the interference assembly to a preset position corresponding to the module height.
5. The method of claim 1, further comprising, prior to the step of driving the interference assembly to move between a plurality of Z-axis positions in the Z-axis direction:
driving the interference assembly and the carrying platform to move relative to each other along the Z-axis direction, so that the photosensitive assembly outputs a plurality of groups of correction interference fringes corresponding to the plane of the carrying platform;
the arithmetic device calculates a plurality of correction fringe contrast values of the plurality of groups of correction interference fringes and finds out a correction Z-axis position of the interference component corresponding to the correction interference fringe with the maximum correction fringe contrast value;
driving an interference objective lens of the interference assembly to move along the Z-axis direction from the correction Z-axis position, so that the photosensitive assembly outputs the multiple groups of correction interference fringes corresponding to multiple platform plane areas; and
the arithmetic device acquires a plurality of displacement data of the interference objective lens at the plurality of Z-axis positions and a plurality of correction displacement data corresponding to a plurality of zero optical path correction positions of the interference objective lens in the plurality of platform plane areas, and calculates the warping degree data of the object to be measured according to the plurality of displacement data and the plurality of correction displacement data.
6. The method of claim 5, further comprising, prior to the step of driving the interference assembly and the stage to move relative to each other along the Z-axis, the step of:
and driving the interference assembly to a corrected height position corresponding to the plane of the carrier.
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