CN112213618A - Probe station focusing method, probe station focusing device, computer equipment and storage medium - Google Patents
Probe station focusing method, probe station focusing device, computer equipment and storage medium Download PDFInfo
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- CN112213618A CN112213618A CN202010971484.XA CN202010971484A CN112213618A CN 112213618 A CN112213618 A CN 112213618A CN 202010971484 A CN202010971484 A CN 202010971484A CN 112213618 A CN112213618 A CN 112213618A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/2851—Testing of integrated circuits [IC]
- G01R31/2886—Features relating to contacting the IC under test, e.g. probe heads; chucks
- G01R31/2891—Features relating to contacting the IC under test, e.g. probe heads; chucks related to sensing or controlling of force, position, temperature
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/60—Control of cameras or camera modules
- H04N23/64—Computer-aided capture of images, e.g. transfer from script file into camera, check of taken image quality, advice or proposal for image composition or decision on when to take image
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/60—Control of cameras or camera modules
- H04N23/67—Focus control based on electronic image sensor signals
Abstract
The application relates to a probe station focusing method, a probe station focusing device, computer equipment and a storage medium, wherein the probe station focusing method comprises the following steps: controlling a slide holder to drive a wafer to perform first motion along a preset direction at a first step distance, and acquiring wafer images of a first motion starting position and a first motion ending position; determining an initial position of a second movement according to the wafer image of the initial position and the wafer image of the termination position; controlling the slide holder to drive the wafer to do second motion along a preset direction according to the initial position; acquiring a wafer image and recording position information after moving the second step distance; the second step distance is smaller than the first step distance; acquiring the definition of the corresponding wafer image according to the plurality of wafer images, and fitting a definition curve according to the position information and the definition of the wafer image corresponding to the corresponding position information; and determining a focusing position according to the definition curve, solving the problem of poor focusing precision and realizing automatic and accurate focusing of the probe station.
Description
Technical Field
The present application relates to the field of integrated circuit testing equipment, and in particular, to a probe station focusing method, apparatus, computer device, and storage medium.
Background
The integrated circuit is a key support for the rapid development of the electronic information industry, the wafer test is an important process for manufacturing the integrated circuit, defective products can be removed in time through accurate test, waste of packaging test cost is reduced, and the product yield is improved. The probe station is used for wafer testing and can automatically complete the electrical performance test of the integrated circuit after being connected with a testing machine. The probe station has the main functions of completing the positioning of the wafer bonding pad and the probe tip in the X direction, the Y direction and the Z direction, and realizing the precise alignment of the wafer bonding pad and the probe tip, namely the alignment process. Wherein the Z-direction position measurement of the pad and tip is a central step in the overall needle targeting process, which is typically observed using a video camera or microscope. Taking a camera as an example, by adjusting the position of the wafer or the probe tip, a wafer image or a probe tip image with higher definition is acquired, and the process of acquiring the best image definition is focusing. The purpose of the probe station focusing is to find the best imaging position, i.e. the focus position. Clear images are powerful criteria for realizing accurate Z-direction distance measurement of the probe station, the focusing positions of the wafer bonding pad and the probe tip are found, accurate Z-direction alignment of the wafer bonding pad and the probe tip can be realized, and the probe alignment process is further completed.
At present, the method widely applied to the Z-direction position measurement of the wafer bonding pad and the probe tip of the probe station is adopted, such as a blind person climbing method, in the climbing process, the falling edge is detected once, namely, the direction turning motion is carried out, and in the direction turning motion process, the motor is easy to generate idle stroke, so that the focusing precision is not ideal.
Disclosure of Invention
The embodiment of the application provides a probe station focusing method, a probe station focusing device, computer equipment and a computer readable storage medium, so as to at least solve the problem of poor focusing precision in the related art.
In a first aspect, an embodiment of the present application provides a probe station focusing method, including:
controlling a slide holder to drive a wafer to perform first motion along a preset direction at a first step distance, and acquiring wafer images of a first motion starting position and a first motion ending position; determining an initial position of a second movement according to the wafer image of the initial position and the wafer image of the termination position; controlling the slide holder to drive the wafer to do second motion along the preset direction according to the initial position; acquiring a wafer image and recording position information after moving the second step distance; the second step distance is smaller than the first step distance; acquiring the definition of the corresponding wafer image according to the plurality of wafer images, and fitting a definition curve according to the position information and the definition of the wafer image corresponding to the corresponding position information; and determining the focusing position according to the definition curve.
In one embodiment, the initial position of the second motion based on the wafer image of the start position and the wafer image of the end position includes: obtaining a first definition according to the wafer image of the initial position and recording initial position information; obtaining a second definition according to the wafer image of the termination position and recording the information of the termination position; calculating a definition difference value according to the first definition and the second definition; and determining the initial position of the second movement according to the definition difference, the initial position information and the end position information.
In one embodiment, the determining the initial position of the second motion according to the sharpness difference, the start position information, and the end position information includes: if the definition difference value is within the preset range, determining the initial position of the second movement according to the initial position information, the end position information and the second step distance; if the definition difference value is smaller than the preset range, determining the initial position of the second movement according to the initial position information and the end position information; and if the definition difference value is larger than the preset range, determining the initial position of the second movement according to the initial position information and the second step distance.
In one embodiment, the controlling the stage to drive the wafer to perform the second motion along the predetermined direction according to the initial position includes: controlling the slide holder to drive the wafer to continuously move by a distance of two steps along a preset direction at a second step from an initial position; when the slide holder moves, acquiring a wafer image of the current position in real time every time a second step distance is moved, calculating the third definition of the wafer image, and recording position information; and determining a second motion stop condition according to the third definition of the wafer images of the three positions and the position information.
In one embodiment, the determining the second motion stop condition according to the third definition of the wafer image at the three positions and the position information comprises: the three positions include: a first position, a second position, and a third position; and if the third definition of the second position wafer image is the corresponding maximum definition of the three positions, a second motion stop condition is met, and the slide holder is controlled to stop moving.
In one embodiment, the determining the second motion stop condition according to the third definition of the wafer image at the three positions and the position information further comprises: if the third definition of the first position wafer image is the corresponding maximum definition of the three positions, resetting the initial position according to the position information and the second step pitch of the first position wafer image; and controlling the slide holder to drive the wafer to continuously move by a distance of two steps along a preset direction by a second step according to the reset initial position, acquiring a wafer image of the current position in real time when the slide holder moves by one second step in the moving process, calculating the third definition of the wafer image, and recording position information until a second motion stop condition is met.
In one embodiment, the determining the second motion stop condition according to the third definition of the wafer image at the three positions and the position information further comprises: if the third definition of the third position wafer image is the corresponding maximum definition of the three positions, controlling the slide holder to move to the fourth position along the preset direction by the second step distance, acquiring the wafer image of the current position, and calculating the third definition of the wafer image; and determining a second motion stop condition according to the third definition and the position information of the wafer image of the second position information, the third position information and the fourth position information until the second motion stop condition is met.
In a second aspect, an embodiment of the present application provides an auto-focusing apparatus, including:
a first motion module: the wafer loading platform is used for controlling the wafer loading platform to drive the wafer to do first motion along the preset direction at a first step distance, and acquiring wafer images of the initial position and the final position of the first motion;
a prejudgment module: the initial position of the second movement is determined according to the wafer image of the initial position and the wafer image of the ending position;
a second motion module: the wafer carrying platform is used for controlling the wafer carrying platform to drive the wafer to do second motion along the preset direction according to the initial position; acquiring a wafer image and recording position information after moving the second step distance; the second step distance is smaller than the first step distance;
a curve fitting module: the device is used for acquiring the definition of the corresponding wafer image according to the plurality of wafer images and fitting a definition curve according to the position information and the definition of the wafer image corresponding to the corresponding position information;
a positioning module: for determining a focus position from the sharpness curve.
In a third aspect, embodiments of the present application provide a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor, when executing the computer program, implements the probe station focusing method according to the first aspect.
In a fourth aspect, embodiments of the present application provide a computer-readable storage medium, on which a computer program is stored, which when executed by a processor, implements the probe station focusing method according to the first aspect.
Compared with the related art, the probe station focusing method provided by the embodiment of the application drives the wafer to make the first motion along the preset direction at the first step distance by controlling the slide holder, and obtains the wafer images of the initial position and the final position of the first motion; determining an initial position of a second movement according to the wafer image of the initial position and the wafer image of the termination position; controlling the slide holder to drive the wafer to do second motion along a preset direction according to the initial position; acquiring a wafer image and recording position information after moving the second step distance; the second step distance is smaller than the first step distance; acquiring the definition of the corresponding wafer image according to the plurality of wafer images, and fitting a definition curve according to the position information and the definition of the wafer image corresponding to the corresponding position information; and determining a focusing position according to the definition curve, solving the problem of poor focusing precision and realizing automatic and accurate focusing of the probe station.
The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below to provide a more thorough understanding of the application.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a schematic view of a fully automated probe station according to the related art;
FIG. 2 is a flow chart of a method for focusing a probe station according to an embodiment of the present application;
FIG. 3 is a schematic view of a first motion profile of an embodiment of the present application;
fig. 4 is a block diagram of the structure of an automatic focusing apparatus according to an embodiment of the present application;
fig. 5 is a hardware configuration diagram of a computer device according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments provided in the present application without any inventive step are within the scope of protection of the present application.
It is obvious that the drawings in the following description are only examples or embodiments of the present application, and that it is also possible for a person skilled in the art to apply the present application to other similar contexts on the basis of these drawings without inventive effort. Moreover, it should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another.
Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of ordinary skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments without conflict.
Unless defined otherwise, technical or scientific terms referred to herein shall have the ordinary meaning as understood by those of ordinary skill in the art to which this application belongs. Reference to "a," "an," "the," and similar words throughout this application are not to be construed as limiting in number, and may refer to the singular or the plural. The present application is directed to the use of the terms "including," "comprising," "having," and any variations thereof, which are intended to cover non-exclusive inclusions; for example, a process, method, system, article, or apparatus that comprises a list of steps or modules (elements) is not limited to the listed steps or elements, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. Reference to "connected," "coupled," and the like in this application is not intended to be limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The term "plurality" as referred to herein means two or more. "and/or" describes an association relationship of associated objects, meaning that three relationships may exist, for example, "A and/or B" may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. Reference herein to the terms "first," "second," "third," and the like, are merely to distinguish similar objects and do not denote a particular ordering for the objects.
The probe station is a key device for testing the electrical parameters and functions of the wafer in the semiconductor production process, and can automatically complete the electrical performance test of the integrated circuit by being connected with a tester. From the middle of the last century to the present, probe station system equipment has developed rapidly, the equipment precision is higher and higher, the automation degree is higher and higher, and the test range is wider and wider. The probe station can be divided into a manual probe station, a semi-automatic probe station and a full-automatic probe station according to the automation degree. Because of low efficiency and low reliability, the prior manual probe station basically belongs to eliminated original products, and the semi-automatic probe station and the full-automatic probe station are widely applied.
The probe station focusing method is mainly applied to a full-automatic probe station. A schematic structural diagram of a fully automatic probe station is shown in fig. 1, and the structure thereof includes: the device comprises a base 1, an XY platform 2, a second camera support 3, a second camera module 4, a support frame 5, a probe card 6, a slide holder 7, a wafer 8 and a first camera module 9. Wherein, XY platform 2 is fixed above base 1, and slide holder 7 and second camera support 3 are fixed in XY platform 2, can realize X, Y direction's rectilinear motion by XY platform drive. The wafer 8 is fixed above the wafer stage 7 through vacuum adsorption, and a lifting device is arranged in the wafer stage and can drive the wafer 8 to do linear motion in the Z direction. The second camera module 4 is fixed on the second camera support 3, and a lifting device is arranged in the second camera support 3 and can drive the second camera module 4 to do linear motion in the Z direction. The probe card 6 and the first camera module 9 are fixed on the support frame 5, the support frame 5 is fixed on the base 1, and the probe card 6 and the first camera module 9 are fixed.
The embodiment also provides a probe station focusing method. Fig. 2 is a flowchart of a probe station focusing method according to an embodiment of the present application, as shown in fig. 2, the flowchart includes the following steps:
step S201, controlling the stage to drive the wafer to perform a first motion along a predetermined direction at a first step distance, and obtaining a wafer image of an initial position and an end position of the first motion.
Specifically, the slide holder is controlled to drive the wafer to move upwards by a first step distance, the preferred length of the first step distance is 30-100 um, and the first movement direction can be upwards movement or downwards movement, which is not limited in the invention. The starting position is preferably within ± 50um of the focus position.
Step S202, determining the initial position of the second movement according to the wafer image of the initial position and the wafer image of the final position.
Specifically, the initial position of the second movement is determined according to the numerical values of the definition of the wafer image at the initial position and the definition of the wafer image at the final position.
In one embodiment, the initial position of the second motion based on the wafer image of the start position and the wafer image of the end position includes: obtaining a first definition according to the wafer image of the initial position and recording initial position information; obtaining a second definition according to the wafer image of the termination position and recording the information of the termination position; calculating a definition difference value according to the first definition and the second definition; and determining the initial position of the second movement according to the definition difference, the initial position information and the end position information. Specifically, the slide holder is controlled to drive the wafer to reach the initial position, the camera captures an image, namely the camera shoots a wafer image of the wafer at the initial position and records position information, the slide holder is controlled to drive the wafer to move to the final position, and in the moving process, the first definition of the wafer image at the initial position is calculated; after the wafer reaches the end position, the camera picks up the image, namely the camera shoots the wafer image of the wafer at the end position and records the position information, and the second definition is calculated according to the wafer image at the end position; subtracting the second definition from the first definition to obtain a definition difference value; and determining the initial position of the second movement according to the definition difference, the starting position information and the ending position information.
In one embodiment, the determining the initial position of the second motion according to the sharpness difference, the start position information, and the end position information includes: if the definition difference value is within the preset range, determining the initial position of the second movement according to the initial position information, the end position information and the second step distance; if the definition difference value is smaller than the preset range, determining the initial position of the second movement according to the initial position information and the end position information; and if the definition difference value is larger than the preset range, determining the initial position of the second movement according to the initial position information and the second step distance. Specifically, the initial position is set to Z1The first resolution is S1The end position is Z2The second resolution is S2The definition difference Δ S is S1-S2, and the second step is Mz; if the definition difference value Delta S is within the preset range, the initial position is determined
If Δ s is smaller than the preset range, the initial position
If Delta S is larger than the preset range, the initial position Z3＝Z1-3×Mz。
Step S203, controlling the slide holder to drive the wafer to do second motion along the preset direction according to the initial position; acquiring a wafer image and recording position information after moving the second step distance; the second step distance is smaller than the first step distance.
Specifically, the initial position is an initial position of the second movement, which is different from the start position and the end position of the first movement. After the initial position of the second movement is determined through the first movement, the slide stage is controlled to drive the wafer to move to the initial position. After the slide holder and the wafer reach the initial position, the slide holder and the wafer move along the preset direction at a second step distance from the initial position; the preset direction is the same as the moving direction of the first movement; the slide holder drives the wafer to obtain the wafer image and record the corresponding position information of the wafer image after the wafer moves by the second step distance, the second step distance is smaller than the first step distance, and the preferred second step distance is 5-20 um.
In one embodiment, the controlling the stage to drive the wafer to perform the second motion along the predetermined direction according to the initial position includes: controlling the slide holder to drive the wafer to continuously move by a distance of two steps along a preset direction at a second step from an initial position; when the slide holder moves, acquiring a wafer image of the current position in real time every time a second step distance is moved, calculating the third definition of the wafer image, and recording position information; and determining a second motion stop condition according to the third definition of the wafer images of the three positions and the position information. Specifically, the slide holder is controlled to drive the wafer to move upwards from the initial position by the distance of two steps at the second step, and when the wafer moves by the distance of one step, the wafer is photographed, the image is taken, the position information is recorded, and the third definition is calculated according to the wafer image in the process that the wafer moves to the next position.
In one embodiment, the determining the second motion stop condition according to the third definition of the wafer image at the three positions and the position information comprises: the three positions include: a first position, a second position, and a third position; and if the third definition of the second position wafer image is the corresponding maximum definition of the three positions, a second motion stop condition is met, and the slide holder is controlled to stop moving. Specifically, the recording initial position is a first position, the first position Z20, and the corresponding third definition is S20; the second position is Z21, the corresponding third definition is S21, the third position is Z22, and the corresponding third definition is S22; and if the definition S21 corresponding to the second position is the maximum value of the definitions S20, S21 and S22 corresponding to the three positions, the second motion stop condition is met, and the slide holder is controlled to stop moving.
In one embodiment, the determining the second motion stop condition according to the third definition of the wafer image at the three positions and the position information further comprises: if the third definition of the first position wafer image is the corresponding maximum definition of the three positions, resetting the initial position according to the position information and the second step pitch of the first position wafer image; and controlling the slide holder to drive the wafer to continuously move by a distance of two steps along a preset direction by a second step according to the reset initial position, acquiring a wafer image of the current position in real time when the slide holder moves by one second step in the moving process, calculating the third definition of the wafer image, and recording position information until a second motion stop condition is met. Specifically, the recording initial position is a first position, the first position Z20, and the corresponding third definition is S20; the second position is Z21, the corresponding third definition is S21, the third position is Z22, and the corresponding third definition is S22; and if the definition S20 corresponding to the first position is the maximum value among the definitions S20, S21 and S22 corresponding to the three positions, resetting the initial position Z30, continuously moving the wafer by a second step distance along the preset direction by the distance of two step distances, acquiring the wafer image of the current position in real time every time the wafer moves by one second step distance in the moving process of the slide holder, calculating the third definition of the wafer image, and recording the position information to obtain a new position Z30, a corresponding third definition S30, a position Z31, a corresponding third definition S31, a position Z32 and a corresponding third definition S32. Repeating the above steps, recording the initial position as the first position, the first position as Z30, and the corresponding third definition as S30; the second position is Z31, the corresponding third definition is S31, the third position is Z32, and the corresponding third definition is S32; and comparing the third definitions corresponding to the three positions until a second motion stop condition is met, and stopping the motion.
In one embodiment, the determining the second motion stop condition according to the third definition of the wafer image at the three positions and the position information further comprises: if the third definition of the third position wafer image is the corresponding maximum definition of the three positions, controlling the slide holder to move to the fourth position along the preset direction by the second step distance, acquiring the wafer image of the current position, and calculating the third definition of the wafer image; and determining a second motion stop condition according to the third definition and the position information of the wafer image of the second position information, the third position information and the fourth position information until the second motion stop condition is met. Specifically, the recording initial position is a first position, the first position Z20, and the corresponding third definition is S20; the second position is Z21, the corresponding third definition is S21, the third position is Z22, and the corresponding third definition is S22; if the definition S22 corresponding to the third position is the maximum value among the definitions S20, S21, and S22 corresponding to the three positions, the wafer moves by one step distance along the preset direction with the second step distance, and the camera captures an image to obtain the third definition S23 and the position information Z23 of the wafer image. And comparing the definition of the three positions by taking Z21 as a first position, Z22 as a second position and Z23 as a third position, and continuing to move according to the comparison result until a second movement stop condition is met.
And S204, acquiring the definition of the corresponding wafer image according to the plurality of wafer images, and fitting a definition curve according to the position information and the definition of the wafer image corresponding to the corresponding position information.
Specifically, when the slide holder and the wafer meet the stop condition, a definition curve is fitted according to the position information of the last three positions of the second movement of the slide holder and the third definition of the wafer image. Specifically, the position information of the last three positions where the wafer is driven by the wafer carrier to make the second motion and the data of the third definition of the wafer image are set as follows: (z)1,S1)，(z2,S2),(z3,S3). And (3) carrying out parabolic fitting, and substituting the data into a one-dimensional quadratic equation set:
solving the equation to obtain the values of the parameters a, b and c, and obtaining a unitary quadratic equation which is a fitting curve.
And S205, determining a focusing position according to the definition curve.
Specifically, the focus position is determined based on the position information corresponding to the peak position of the curve.
In one embodiment, the position information corresponding to the sharpness peak in the sharpness curve is used as the focus position. Specifically, according to the curve equation, the position information of the focus position is:
the resolution of the focus position is:
the focusing accuracy of the focusing position is ± 1.5um, i.e., the error of the focusing position is ± 1.5 um. The focusing position is found by adopting a curve fitting method, the focusing precision is ensured on the basis of quickly realizing automatic focusing, and the quick and accurate focusing of the full-automatic probe station is realized.
In the prior art, the hill climbing method is simple and easy to implement, has good focusing effect and is widely applied to the engineering field. The principle of the hill climbing method is as follows: the blind person climbing method is characterized in that climbing is simulated, the blind person starts from a starting point along a certain direction, climbing is started with a certain large step length to change the focal length, the definition evaluation value at each time is calculated to be compared, when the falling edge of the slope is detected, the step length is reduced, the slope climbing is carried out in the reverse direction, the repeated turning back is carried out, the climbing is stopped until the step length is reduced to a preset termination step length, and the peak position in the last climbing process is the maximum value searched by the blind person climbing method. However, the hill climbing method has its own limitations, and firstly, a single detection of the falling edge, i.e., the turning direction, may cause the probe station to sink into a local mechanism or turn back at a position deviating from the maximum value, and in addition, the slide stage turns back for many times to cause the idle stroke of the motor, which affects the focusing accuracy, resulting in an unsatisfactory focusing effect. Secondly, the repeated foldback process takes a lot of time, making the autofocus time longer.
The invention aims to position the focusing position in the Z-axis direction, and the method can be applied to not only wafers but also probes for focusing. The initial position of the second movement is determined through the first movement by combining the first movement with a larger step pitch and the second movement with a smaller step pitch, and the first movement and the second movement both adopt upward movement or downward movement, so that the one-way movement of the slide holder is ensured, the idle stroke problem caused by multiple turn-back is solved, and the focusing precision is improved; meanwhile, the calculation of the definition of the wafer image and the movement of the slide holder are carried out simultaneously, so that the calculation time of the definition is saved, and the focusing time is shortened; in addition, the focusing position is searched by adopting a curve fitting method, so that the problem that the algorithm of the probe station falls into a local extreme value or returns at a position deviated from the maximum value is solved, the focusing time is shortened, and the focusing efficiency is improved.
The embodiments of the present application are described and illustrated below by means of preferred embodiments.
When the probe station starts to work, the probe station sends a control command to control the slide holder to drive the wafer to move to the initial position, the slide holder drives the wafer to stop after the wafer reaches the initial position, the camera shoots a wafer image of the wafer at the initial position, the first definition S1 is calculated, and position information z1 is recorded, wherein z1 is 0; the wafer is driven by the wafer carrying table to move upwards by a first step distance of 100um, the wafer carrying table drives the wafer to reach the end position and then stops, the camera shoots the wafer image of the wafer at the end position, the second definition S2 is calculated, and position information z2 is recorded, wherein z2 is 0+100um or 100 um; wherein, the calculation time of single definition is less than 200 milliseconds, and the calculation time of single definition includes: the wafer motion time, the camera image taking time and the definition value calculating time. Comparing the first definition S1 with the second definition S2 to determine the starting position of the second movement; fig. 3 is a schematic view of a first motion situation according to an embodiment of the present application, as shown in fig. 3, where 1 denotes a start position and 2 denotes an end position. In the figure, B, E indicates that the first definition is similar to the second definition, A, C indicates that the first definition is smaller than the second definition, and D, F indicates that the first definition is greater than the second definition. Preferred preset ranges are: the ratio of the difference between the first definition and the second definition to the first definition is within five percent, i.e.
The first definition is considered similar to the second definition. If the ratio of the difference to the first resolution is within the predetermined range, and the second step size Mz is 10um, thenInitial position
And recording the initial position as Z20 um which is 30um, controlling the slide holder to move upwards by the distance of two steps, taking pictures by the camera every time the slide holder moves by the distance of one step, calculating the definition of the wafer image at the position and recording the position information, wherein the corresponding definition is S20. Marking the first position as Z2030um, corresponding to clear S20The second position is Z2140um, corresponding to resolution S21The third position is Z2250um, corresponding to resolution S22. And if the definition corresponding to the second position is the maximum definition corresponding to the three positions, a second motion stop condition is met, and the slide holder is controlled to stop moving.
And performing curve fitting according to the wafer image definition and the position information of the last three stop positions, selecting the position information corresponding to the curve peak value to obtain a focusing position, and sending a control instruction by the probe station to control the slide holder to drive the wafer to move to the focusing position to finish focusing.
It should be noted that the steps illustrated in the above-described flow diagrams or in the flow diagrams of the figures may be performed in a computer system, such as a set of computer-executable instructions, and that, although a logical order is illustrated in the flow diagrams, in some cases, the steps illustrated or described may be performed in an order different than here.
The present embodiment further provides an automatic focusing apparatus, which is used to implement the foregoing embodiments and preferred embodiments, and the description of the automatic focusing apparatus is omitted here. As used hereinafter, the terms "module," "unit," "subunit," and the like may implement a combination of software and/or hardware for a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.
Fig. 4 is a block diagram of an auto-focusing apparatus according to an embodiment of the present application, as shown in fig. 5, the apparatus including:
the first motion module 10: the wafer loading platform is used for controlling the wafer loading platform to drive the wafer to do first motion along the preset direction at the first step distance, and obtaining the wafer image of the initial position and the final position of the first motion.
The prejudgment module 20: and the initial position of the second motion is determined according to the wafer image of the initial position and the wafer image of the ending position.
The second motion module 30: the wafer carrying platform is used for controlling the wafer carrying platform to drive the wafer to do second motion along the preset direction according to the initial position; acquiring a wafer image and recording position information after moving the second step distance; the second step distance is smaller than the first step distance.
The curve fitting module 40: and the device is used for acquiring the definition of the corresponding wafer image according to the plurality of wafer images and fitting a definition curve according to the position information and the definition of the wafer image corresponding to the corresponding position information.
The positioning module 50: for determining a focus position from the sharpness curve.
The above modules may be functional modules or program modules, and may be implemented by software or hardware. For a module implemented by hardware, the modules may be located in the same processor; or the modules can be respectively positioned in different processors in any combination.
In addition, the probe station focusing method described in the embodiment of the present application with reference to fig. 1 can be implemented by a computer device. Fig. 5 is a hardware structure diagram of a computer device according to an embodiment of the present application.
The computer device may comprise a processor 51 and a memory 52 in which computer program instructions are stored.
Specifically, the processor 51 may include a Central Processing Unit (CPU), or A Specific Integrated Circuit (ASIC), or may be configured to implement one or more Integrated circuits of the embodiments of the present Application.
The memory 52 may be used to store or cache various data files that need to be processed and/or used for communication, as well as possible computer program instructions executed by the processor 51.
The processor 51 implements any of the probe station focusing methods in the above embodiments by reading and executing computer program instructions stored in the memory 52.
In some of these embodiments, the computer device may also include a communication interface 53 and a bus 5. As shown in fig. 5, the processor 51, the memory 52, and the communication interface 53 are connected via the bus 5 to complete mutual communication.
The communication interface 53 is used for implementing communication between modules, apparatuses, units and/or devices in the embodiments of the present application. The communication port 53 may also be implemented with other components such as: the data communication is carried out among external equipment, image/data acquisition equipment, a database, external storage, an image/data processing workstation and the like.
The bus 5 comprises hardware, software, or both coupling the components of the computer device to each other. Bus 5 includes, but is not limited to, at least one of the following: data Bus (Data Bus), Address Bus (Address Bus), Control Bus (Control Bus), Expansion Bus (Expansion Bus), and Local Bus (Local Bus). By way of example, and not limitation, Bus 5 may include an Accelerated Graphics Port (AGP) or other Graphics Bus, an Enhanced Industry Standard Architecture (EISA) Bus, a Front-Side Bus (FSB), a Hyper Transport (HT) Interconnect, an ISA (ISA) Bus, an InfiniBand (InfiniBand) Interconnect, a Low Pin Count (LPC) Bus, a memory Bus, a microchannel Architecture (MCA) Bus, a PCI (Peripheral Component Interconnect) Bus, a PCI-Express (PCI-X) Bus, a Serial Advanced Technology Attachment (SATA) Bus, a Video Electronics Bus (audio Electronics Association), abbreviated VLB) bus or other suitable bus or a combination of two or more of these. Bus 5 may include one or more buses, where appropriate. Although specific buses are described and shown in the embodiments of the application, any suitable buses or interconnects are contemplated by the application.
The computer device may execute the probe station focusing method in the embodiment of the present application based on the acquired computer program instructions, thereby implementing the probe station focusing method described in conjunction with fig. 1.
In addition, in combination with the probe station focusing method in the foregoing embodiments, the embodiments of the present application may provide a computer readable storage medium to implement. The computer readable storage medium having stored thereon computer program instructions; the computer program instructions, when executed by a processor, implement any of the probe station focusing methods of the above embodiments.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method of focusing a probe station, comprising:
controlling a slide holder to drive a wafer to perform first motion along a preset direction at a first step distance, and acquiring wafer images of a first motion starting position and a first motion ending position;
determining an initial position of a second movement according to the wafer image of the initial position and the wafer image of the termination position;
controlling the slide holder to drive the wafer to do second motion along the preset direction according to the initial position; acquiring a wafer image and recording position information after moving the second step distance; the second step distance is smaller than the first step distance;
acquiring the definition of the corresponding wafer image according to the plurality of wafer images, and fitting a definition curve according to the position information and the definition of the wafer image corresponding to the corresponding position information;
and determining the focusing position according to the definition curve.
2. The probe station focusing method of claim 1, wherein determining the initial position of the second motion from the wafer image of the start position and the wafer image of the end position comprises:
obtaining a first definition according to the wafer image of the initial position and recording initial position information;
obtaining a second definition according to the wafer image of the termination position and recording the information of the termination position;
calculating a definition difference value according to the first definition and the second definition;
and determining the initial position of the second movement according to the definition difference, the initial position information and the end position information.
3. The probe station focusing method of claim 1, wherein determining the initial position of the second motion based on the sharpness difference, the start position information, and the end position information comprises:
if the definition difference value is within the preset range, determining the initial position of the second movement according to the initial position information, the end position information and the second step distance;
if the definition difference value is smaller than the preset range, determining the initial position of the second movement according to the initial position information and the end position information;
and if the definition difference value is larger than the preset range, determining the initial position of the second movement according to the initial position information and the second step distance.
4. The method of claim 1, wherein controlling the stage to drive the wafer to perform a second motion along a predetermined direction according to the initial position comprises:
controlling the slide holder to drive the wafer to continuously move by a distance of two steps along a preset direction at a second step from an initial position;
when the slide holder moves, acquiring a wafer image of the current position in real time every time a second step distance is moved, calculating the third definition of the wafer image, and recording position information;
and determining a second motion stop condition according to the third definition of the wafer images of the three positions and the position information.
5. The probe station focusing method of claim 4, wherein determining a second motion stop condition based on a third definition of a wafer image of three locations and location information comprises:
the three positions include: a first position, a second position, and a third position;
and if the third definition of the second position wafer image is the corresponding maximum definition of the three positions, a second motion stop condition is met, and the slide holder is controlled to stop moving.
6. The probe station focusing method of claim 5, wherein determining a second motion stop condition based on a third definition of a wafer image of three locations and location information further comprises:
if the third definition of the first position wafer image is the corresponding maximum definition of the three positions, resetting the initial position according to the position information and the second step pitch of the first position wafer image;
and controlling the slide holder to drive the wafer to continuously move by a distance of two steps along a preset direction by a second step according to the reset initial position, acquiring a wafer image of the current position in real time when the slide holder moves by one second step in the moving process, calculating the third definition of the wafer image, and recording position information until a second motion stop condition is met.
7. The probe station focusing method of claim 5, wherein determining a second motion stop condition based on a third definition of a wafer image of three locations and location information further comprises:
if the third definition of the third position wafer image is the corresponding maximum definition of the three positions, controlling the slide holder to move to the fourth position along the preset direction by the second step distance, acquiring the wafer image of the current position, and calculating the third definition of the wafer image;
and determining a second motion stop condition according to the third definition and the position information of the wafer image of the second position information, the third position information and the fourth position information until the second motion stop condition is met.
8. An auto-focusing device, comprising:
a first motion module: the wafer loading platform is used for controlling the wafer loading platform to drive the wafer to do first motion along the preset direction at a first step distance, and acquiring wafer images of the initial position and the final position of the first motion;
a prejudgment module: the initial position of the second movement is determined according to the wafer image of the initial position and the wafer image of the ending position;
a second motion module: the wafer carrying platform is used for controlling the wafer carrying platform to drive the wafer to do second motion along the preset direction according to the initial position; acquiring a wafer image and recording position information after moving the second step distance; the second step distance is smaller than the first step distance;
a curve fitting module: the device is used for acquiring the definition of the corresponding wafer image according to the plurality of wafer images and fitting a definition curve according to the position information and the definition of the wafer image corresponding to the corresponding position information;
a positioning module: for determining a focus position from the sharpness curve.
9. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the probe station focusing method of any one of claims 1 to 7 when executing the computer program.
10. A computer-readable storage medium on which a computer program is stored, the program, when executed by a processor, implementing the probe station focusing method of any of claims 1 to 7.
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