WO2022205493A1

WO2022205493A1 - Test platform

Info

Publication number: WO2022205493A1
Application number: PCT/CN2021/086366
Authority: WO
Inventors: 柯百龙; 王涛
Original assignee: 台湾积体电路制造股份有限公司; 台积电(中国)有限公司
Priority date: 2021-04-01
Filing date: 2021-04-12
Publication date: 2022-10-06
Also published as: CN213456087U

Abstract

A test platform, which is used for monitoring the operation precision of equipment (S) to be tested. The test platform comprises: a base (1), comprising a fixing frame (11) and a reference piece (12) connected to the fixing frame (11), the fixing frame (11) being used for fixing the equipment (S), and the reference piece (12) being provided with a reference surface (B) facing a moving part (M) of the equipment (S); a driving apparatus (2), which is connected to the base (1) and is used for providing power for the moving part; a sensing unit (3), which is arranged on the moving part and is used for sensing the distance or angle between the moving part (M) and the reference surface (B) after the moving part (M) moves to a designated position (P2); and a data processing unit (4), which is configured to determine whether the equipment (S) meets acceptance requirements according to the deviation between the distance sensed by the sensing unit (3) and a preset distance or the deviation between the angle and a preset angle. The test platform may automatically monitor the operation precision of the equipment (S) and carry out quantifiable data analysis, so that the test efficiency and the reliability of test results are improved.

Description

testing platform

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Chinese Patent Application No. 202120669587.0, filed on April 1, 2021, entitled "Test Platform", the entire contents of which are incorporated herein by reference.

technical field

The present application relates to the field of semiconductor technology, and in particular, to a test platform.

Background technique

In the field of semiconductor device manufacturing, lithography is a very critical process. The general lithography process needs to go through the steps of cleaning and drying the surface of the silicon wafer, priming, spin-coating photoresist, soft baking, alignment exposure, post-baking, developing, hard baking, and etching. To accomplish these processes, various equipment is usually designed to carry the wafers. Before these equipments are officially put into use or after failure maintenance, it is usually necessary to check the operation accuracy of the equipment. If the equipment runs for a long time, it is necessary to arrange for operators to monitor these equipment to avoid accidental impact on the test results, and the test cost is high.

SUMMARY OF THE INVENTION

The purpose of the present application is to provide a test platform that can automatically monitor the running accuracy of the device under test.

To this end, an embodiment of the present application proposes a test platform for monitoring the running accuracy of the device to be tested. The test platform includes: a base, a fixing frame and a reference piece connected to the fixing frame, and the fixing frame is used to fix the to-be-tested device. testing equipment, the reference piece has a reference surface facing the moving part of the equipment to be tested; a driving device is connected to the base, and the driving device is used to provide power for the moving part; the sensing unit is arranged on the moving part and is used for sensing motion The distance or angle between the component and the reference plane after the component moves to the designated position; the data processing unit is configured to judge according to the deviation between the distance sensed by the sensing unit and the preset distance or the deviation between the angle and the preset angle Whether the device under test meets the acceptance requirements.

According to an aspect of the embodiments of the present application, the sensing unit includes at least three displacement sensors, and the at least three displacement sensors are disposed on a plane of the moving part facing the reference plane side.

According to an aspect of the embodiments of the present application, in each operating cycle of the moving part, the mean value of the deviation between the distances sensed by the at least three displacement sensors and the preset distance or the mean value of the absolute value of the deviation between the angle and the preset angle is a, the deviation threshold of the device under test is b, and if a≤b, the data processing unit determines that the device under test meets the acceptance requirements.

According to an aspect of the embodiments of the present application, in the ith operating cycle of the moving part, the mean absolute value of the deviation between the distances sensed by the at least three displacement sensors and the preset distance or the deviation between the angle and the preset angle The mean absolute value is a _i , where 0<i≤n, i and n are natural numbers, the deviation threshold of the device under test is b, the precision index of the moving part is T, and

If T≤0.5, and the device to be tested is a new device that has not been put into use, the data processing unit determines that the device to be tested meets the acceptance requirements of the new device.

According to an aspect of the embodiments of the present application, if 0.5<T≤1, and the device to be tested is an old device after repair, the data processing unit determines that the device to be tested meets the acceptance requirements of the old device.

According to an aspect of the embodiments of the present application, if 1<T≤2, and the device to be tested is an old device after repair, the data processing unit determines that the device to be tested meets the acceptance requirements of the old device within the limited service period.

According to an aspect of the embodiment of the present application, if T>2, and the device under test is an old device after repair, the data processing unit determines that the device under test does not meet the acceptance requirements.

According to an aspect of the embodiments of the present application, the moving part moves from an initial position to a designated position, and the test platform further includes a first sensor and a second sensor disposed on the fixing frame, the first sensor corresponding to the initial position setting, and the second sensor corresponding to Set at a designated position; when the moving part reaches the initial position, the first sensor outputs a first electrical signal; when the moving part reaches the designated position, the second sensor outputs a second electrical signal.

According to an aspect of the embodiments of the present application, the test platform further includes a relay, the relay is electrically connected to the driving device, the relay turns off the driving device according to the first electrical signal sent by the first sensor, and starts the driving device to rotate forward after a first predetermined time interval ; The relay closes the drive device according to the second electrical signal sent by the second sensor, and starts the drive device to rotate in reverse after a second predetermined time interval.

According to one aspect of the embodiments of the present application, the device to be tested is a carrier device for lifting wafers, the moving component is a carrier platform that moves back and forth in a vertical direction, and the sensing unit is used to sense when the carrier platform moves to a designated position. The distance between it and the reference plane to detect the flatness of the carrying platform.

A test platform provided by an embodiment of the present application includes a base, a driving device, a sensing unit and a data processing unit. The base includes a fixing frame and a reference piece connected to the fixing frame. The fixing frame is used to fix the device to be tested, and the reference The device has a reference plane facing the moving part of the device to be tested; the driving device is connected to the base, and the driving device is used to provide power for the moving part; the sensing unit is arranged on the moving part and is used to sense the moving part after it has moved to a designated position The distance or angle between it and the reference plane; the data processing unit is configured to judge whether the device under test meets the acceptance requirements according to the deviation between the distance sensed by the sensing unit and the preset distance or the deviation between the angle and the preset angle . The test platform can automatically monitor the running accuracy of the equipment under test and perform quantifiable data analysis, which improves the test efficiency and the reliability of the test results.

Description of drawings

The present application can be better understood from the following description of specific embodiments of the present application in conjunction with the accompanying drawings, wherein other features, objects and advantages of the present application can be better understood by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings. It will become apparent that the same or similar reference numbers refer to the same or similar features.

FIG. 1 shows a schematic structural diagram of a test platform testing a device under test according to an embodiment of the present application;

2 shows a schematic structural diagram of a test platform according to an embodiment of the present application;

FIG. 3 is a graph showing the running accuracy of the device under test tested by the test platform in FIG. 2 .

Description of reference numbers:

S-equipment to be tested; M-moving parts; B-reference plane; P1-initial position; P2-designated position;

1-base; 11-fixed frame; 12-reference piece;

2-drive device; 3-sensing unit; 31-displacement sensor;

4-data processing unit; 5-first sensor; 6-second sensor; 7-relay.

Detailed ways

Features and exemplary embodiments of various aspects of the present application are described in detail below. Numerous specific details are disclosed in the following detailed description to provide a thorough understanding of the present application. However, it will be apparent to those skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating examples of the present application. The present application is in no way limited to any specific configurations and algorithms set forth below, but covers any modifications, substitutions and improvements of elements, components and algorithms without departing from the spirit of the present application. In the drawings and the following description, well-known structures and techniques have not been shown in order to avoid unnecessarily obscuring the present application.

In the field of semiconductor device manufacturing, lithography is a very critical process. The general lithography process needs to go through the steps of cleaning and drying the surface of the silicon wafer, priming, spin-coating photoresist, soft baking, alignment exposure, post-baking, developing, hard baking, and etching. To accomplish these processes, various equipment is usually designed to carry the wafers. For example, an etching machine commonly used in a photolithography process includes a wafer carrier platform, which can be raised and lowered in a vertical direction for lifting the wafer. Before these equipments, such as etching machines, are put into use formally or after failure maintenance, it is necessary to check whether the operation accuracy of the equipment meets the acceptance requirements.

In order to improve the reliability of the test results, the equipment usually runs continuously for 24 hours or longer. It is necessary to arrange engineers to monitor these equipment to avoid accidental influence on the test results, and the test cost is high.

In view of this, the embodiments of the present application provide a test platform, which can automatically monitor the running accuracy of the device under test.

FIG. 1 shows a schematic structural diagram of a test platform for testing a device under test according to an embodiment of the present application.

As shown in FIG. 1 , a test platform provided by the embodiment of the present application is used to monitor the running accuracy of the equipment under test S, and the test platform includes: a base 1 , a driving device 2 , a sensing unit 3 and a data processing unit 4 .

The base 1 includes a fixing frame 11 and a reference member 12 connected with the fixing frame 11 . The fixing frame 11 is used to fix the device S to be tested, and the reference member 12 has a reference plane B facing the moving part M of the device S to be tested.

The driving device 2 is connected with the base 1 , and the driving device 2 is used to provide power for the moving part M.

The sensing unit 3 is disposed on the moving part M, and is used to sense the distance or angle between the moving part M and the reference plane B after the moving part M moves to the designated position P2.

The data processing unit 4 is configured to judge whether the device under test S meets the acceptance requirements according to the deviation between the distance sensed by the sensing unit 3 and the preset distance or the deviation between the angle and the preset angle.

For convenience of description, the embodiments of the present application are described by taking the device under test S shown in FIG. 1 as an example as a carrier device for lifting wafers. Optionally, the carrying device is disposed between the fixed frame 11 of the base 1 and the reference member 12, and the moving part M is a carrying platform that moves back and forth in the vertical direction. The sensing unit 3 is disposed on the carrying platform, and is used for sensing the distance between the carrying platform and the reference plane B after the carrying platform moves to the designated position P2, so as to detect the flatness of the carrying platform.

In actual normal operation, the equipment under test S drives the bearing platform to move back and forth in the vertical direction through a lifting device, such as a combination of a ball screw and a nut, a combination of a worm gear and a nut, and other structural forms. When the test platform is tested, the driving device 2 replaces the lifting device to drive the carrying platform to move back and forth in the vertical direction. The driving device 2 can be, for example, but not limited to, a driving motor, an air cylinder or a hydraulic cylinder, etc., as long as it can drive the carrying platform to move back and forth in the vertical direction. Since the test platform can automatically drive the moving parts M of the equipment to be tested S to move back and forth through the driving device 2, there is no need to arrange an engineer to monitor the operation of the equipment S to be tested, which reduces labor costs.

When the carrying platform moves to the designated position P2, the sensing unit 3 senses the distance between the carrying platform and the reference plane B. The data processing unit 4 can determine the flatness of the carrying platform according to the deviation between the distance sensed by the sensing unit 3 and the preset distance, and judge whether the device under test S meets the acceptance requirements through quantifiable data analysis.

It can be understood that the structural form of the base 1 is not limited, and is determined according to the structure of the device S to be inspected. If the motion form of the moving part M of the device S to be tested is rotational motion, the sensing unit 3 is used to sense the angle between the moving part M and the reference plane B after the moving part M moves to the designated position P2. The deviation between the angle sensed by the measuring unit 3 and the preset angle is used to judge whether the device under test S meets the acceptance requirements.

A test platform provided in the embodiment of the present application includes a base 1, a driving device 2, a sensing unit 3 and a data processing unit 4. The base 1 includes a fixing frame 11 and a reference piece 12 connected to the fixing frame 11. The fixing frame 11 is used to fix the device to be tested, the reference piece 12 has a reference plane B facing the moving part M of the device to be tested S; the driving device 2 is connected to the base 1, and the driving device 2 is used to provide power for the moving part M; the sensing unit 3 is arranged on the moving part M, and is used to sense the distance or angle between the moving part M and the reference plane B after the moving part M moves to the designated position P2; the data processing unit 4 is configured to The deviation between the set distances or the deviation between the angle and the preset angle is used to judge whether the device S to be tested meets the acceptance requirements. The test platform can automatically monitor the running accuracy of the equipment under test S, and perform quantifiable data analysis, which improves the test efficiency and the reliability of the test results.

The specific structure of the test platform provided by the embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

FIG. 2 shows a schematic structural diagram of a test platform according to an embodiment of the present application, and FIG. 3 shows a graph of the running accuracy of the device under test tested by the test platform in FIG. 2 .

As shown in FIG. 2 , the sensing unit 3 includes at least three displacement sensors 31 , and the at least three displacement sensors 31 are disposed on the plane of the moving part M facing the reference plane B side. When the motion form of the moving part M is linear motion, the displacement sensor 31 is a distance sensor. When the motion form of the moving part M is rotational motion, the displacement sensor 31 is an angle sensor. The greater the number of displacement sensors 31, the more accurate the measured data. At least three displacement sensors 31 can determine the distance or angle between the moving part M and the reference plane B when the moving part M reaches the designated position P2, and then determine the flatness of the moving part M.

Further, in each operating cycle of the moving part M, the mean absolute value of the deviation between the distances sensed by the at least three displacement sensors 31 and the preset distance or the mean deviation between the angle and the preset angle is a, and the mean value is a. The deviation threshold of the device under test S is b, and if a≤b, the data processing unit 4 determines that the device under test S meets the acceptance requirements.

The device under test S is still taken as an example of a carrier device for lifting wafers for description. The moving part M is a liftable carrying platform. The carrying platform rises from the initial position P1 to the designated position P2, and then descends from the designated position P2 to the initial position P1. It is a running cycle. During this running cycle, the carrying platform is at the designated position P2. The distance from the reference plane B is the test distance. Generally, the test process will include multiple operation cycles, and the mean absolute value a of the deviation between the test distance and the preset distance sensed by the at least three displacement sensors 31 in each operation cycle is not greater than the deviation threshold b, then the data processing unit 4 It is judged that the equipment under test S meets the acceptance requirements.

As shown in FIG. 3 , the distance deviation data curve in 5 operating cycles measured by the three displacement sensors 31 is shown. Among them, the distance deviations in the five operating cycles measured by the first displacement sensor 31 are respectively -0.08mm, -0.03mm, +0.02mm, -0.07mm, and -0.05mm; The distance deviations in the 5 running cycles are respectively +0.05mm, -0.02mm, +0.09mm, -0.10mm, +0.08mm; the distance deviations in the 5 running cycles measured by the third displacement sensor 31 are respectively - 0.08mm, -0.02mm, +0.095mm, -0.10mm, +0.09mm; then the mean absolute values of the deviations measured by the three displacement sensors 31 in the five operating cycles are 0.07mm, 0.047mm, 0.068mm, 0.09 mm, 0.073mm, both less than the deviation threshold b=0.1mm. Thus, the data processing unit 4 determines that the flatness of the carrying platform meets the requirements of the running accuracy, that is, the device S to be tested meets the requirements for acceptance.

According to the above measurement values, it can be seen that the mean absolute value of deviation a≤b in each operating cycle, but some mean absolute values of deviation a are close to the deviation threshold b, and some mean absolute values of deviation a are far from the deviation threshold b. If the number of running cycles is more, there may be some deviation absolute value mean a that exceeds the deviation threshold b. In order to more comprehensively evaluate the operation accuracy of the equipment to be inspected, the equipment accuracy index can be used to evaluate.

The equipment accuracy index is a parameter to measure whether the machine equipment has the comprehensive accuracy to meet the production needs. It is an important data to evaluate the mutual position change of the various parts caused by the physical wear of the machine equipment. The smaller the equipment accuracy index value, the higher the accuracy. . The evaluation method of the equipment accuracy index is obtained by using the mathematical statistics method in the machine tool accuracy inspection, so it is often used in the evaluation of machine tool equipment. For other equipment, if quantitative standards are set for all technical quality requirements, this method can also be used to evaluate.

The equipment accuracy index T is calculated by the following formula (1) by calculating the measured value (Tp) of each accuracy of the equipment and the specified tolerance value (Ts) within the number of measurement items (n).

In the embodiment of the present application, in the ith operating cycle of the moving part M, the mean absolute value of the deviation between the distances sensed by the at least three displacement sensors 31 and the preset distance or the deviation between the angle and the preset angle The mean absolute value is a _i , where 0<i≤n, i and n are natural numbers, the deviation threshold of the device under test S is b, the precision index of the moving part M is T, and

According to practical experience, the inventor has concluded that if T≤0.5, and the device under test S is a new device that has not been put into use, the data processing unit 4 determines that the device under test S meets the acceptance requirements of the new device.

If 0.5<T≤1, and the equipment under test S is an old equipment after maintenance, the data processing unit 4 judges that the equipment under test S meets the acceptance requirements of the old equipment.

If 1<T≤2, and the equipment under test S is an old equipment after maintenance, the data processing unit 4 determines that the equipment under test S meets the acceptance requirements of the old equipment within the limited service period. For example, if the equipment in normal use needs to be overhauled after one year of use, the equipment needs to be overhauled after six months of use, and its equipment accuracy index will be tested after the overhaul.

If T>2, and the equipment under test S is an old equipment after maintenance, the data processing unit 4 judges that the equipment under test S does not meet the acceptance requirements. At this time, the equipment S to be inspected needs to undergo key maintenance. If the inspection and acceptance requirements are still not met after the key maintenance, it will be discarded.

Taking the distance deviation data curve data in 5 operating cycles measured by the three displacement sensors 31 shown in FIG. 3 as an example, n=5, the mean absolute value of the deviation a1=0.07mm, a2=0.047mm, a3=0.068mm , a4=0.09mm, a5=0.073mm, and the deviation threshold b=0.1mm, then T=0.682.

If the device to be tested S is a new device that has not been put into use, the data processing unit 4 determines that the device to be tested S does not meet the acceptance requirements of the new device. If the device S to be tested is an old device after maintenance, the data processing unit 4 determines that the device S to be tested meets the acceptance requirements of the old device.

It can be understood that, in order to improve the measurement accuracy of the test platform, data in multiple operation cycles should be measured, and the more measurement data, the higher the accuracy of the measurement results. Since the equipment accuracy index T takes into account the geometric accuracy and working accuracy, the equipment S to be inspected is comprehensively evaluated from two dimensions, which improves the reliability of the measurement results.

In some embodiments, as shown in FIG. 1 , in order to improve the accuracy of the running position of the device S to be tested and the accuracy of the measurement results, the test platform further includes a first sensor 5 and a second sensor arranged on the fixing frame 11 6. The first sensor 5 is set corresponding to the initial position P1, and the second sensor 6 is set corresponding to the designated position P2; when the moving part M reaches the initial position P1, the first sensor 5 outputs the first electrical signal, and when the moving part M reaches the designated position At the position P2, the second sensor 6 outputs a second electrical signal.

Optionally, both the first sensor 5 and the second sensor 6 are position sensors, such as infrared sensors or photoelectric sensors arranged in pairs.

Further, the test platform provided in the embodiment of the present application further includes a relay 7, which is electrically connected to the driving device 2, and the relay 7 turns off the driving device 2 according to the first electrical signal sent by the first sensor 5, and after a first predetermined time interval. The driving device 2 is started to rotate in the forward direction, the driving device 2 is turned off according to the second electrical signal sent by the second sensor 6, and the driving device 2 is started to rotate in the reverse direction after a second predetermined time interval.

For example, the relay 7 starts the driving device 2 to rotate in the forward direction, so that the driving device 2 drives the carrying platform to rise from the initial position P1 to the designated position P2, and then the relay 7 receives the second electrical signal sent by the second sensor 6, and turns off the driving device 2. The sensing unit 3 senses the distance between the carrying platform and the reference plane B, and after a second predetermined time interval, such as 1s, starts the driving device 2 to rotate in the reverse direction, and the driving device 2 drives the carrying platform to descend from the designated position P2 to the initial position P1; At this time, the relay 7 receives the first electrical signal sent by the first sensor 5, turns off the driving device 2, and completes a running cycle. After a first predetermined time interval, eg, 2 s, the driving device 2 is restarted to rotate in the forward direction, and the cycle of the next operation cycle is started.

In the embodiment of the present application, through the cooperation of the relay 7 with the first sensor 5 and the second sensor 6, the starting and closing of the driving device 2 can be controlled continuously and orderly, the automatic control of the test process is realized, and the test efficiency is improved. Save labor costs.

Therefore, the test platform provided by the embodiment of the present application has a simple structure, is light and convenient, and is easy to operate, and can automatically monitor the running accuracy of the device S to be tested, and perform quantifiable data analysis, and can also analyze the geometric accuracy and working accuracy from the Two dimensions are used to evaluate the operation accuracy of the equipment to be inspected, which improves the test efficiency and the reliability of the test results.

It should be noted that the test platform provided by the embodiment of the present application can not only measure the running accuracy of the wafer carrier, but also can be used for other occasions where the equipment to be tested needs to be measured, and details are not repeated here.

Those skilled in the art should understand that the above-mentioned embodiments are all illustrative and not restrictive. Different technical features appearing in different embodiments can be combined to achieve beneficial effects. Those skilled in the art should be able to understand and implement other variant embodiments of the disclosed embodiments on the basis of studying the drawings, the description and the claims. In the claims, the term "comprising" does not exclude other means or steps; an item is intended to include one/one or more/kinds of items when not modified by a quantifier, and may be combined with "one/one or more/kinds of items" "Used interchangeably"; the terms "first", "second" are used to designate names and not to indicate any particular order. Any reference signs in the claims should not be construed as limiting the scope of protection. The functions of the multiple parts appearing in the claims can be realized by a single hardware or software module. The appearance of certain technical features in different dependent claims does not mean that these technical features cannot be combined to achieve beneficial effects.

Claims

A test platform for monitoring the running accuracy of a device to be tested, the test platform includes:

a base, comprising a fixing frame and a reference piece connected with the fixing frame, the fixing frame is used to fix the device under test, and the reference piece has a reference plane facing the moving part of the device under test;

a driving device, connected with the base, the driving device is used to provide power for the moving part;

a sensing unit, arranged on the moving part, for sensing the distance or angle between the moving part and the reference plane after the moving part moves to a specified position;

A data processing unit configured to judge whether the device under test meets the acceptance requirements according to the deviation between the distance sensed by the sensing unit and the preset distance or the deviation between the angle and the preset angle.
The test platform according to claim 1, wherein the sensing unit comprises at least three displacement sensors, and the at least three displacement sensors are disposed on a plane of the moving part facing the reference plane side.
The test platform according to claim 2, wherein in each operating cycle of the moving part, the mean value of the deviation between the distances sensed by the at least three displacement sensors and the preset distance or the angle and the preset distance It is assumed that the mean absolute value of the deviation between angles is a, and the deviation threshold of the device under test is b. If a≤b, the data processing unit judges that the device under test meets the acceptance requirements.
The test platform according to claim 2, wherein, in the i-th operation cycle of the moving part, the absolute value of the deviation between the distances sensed by the at least three displacement sensors and the preset distance is the mean value or the The mean absolute value of the deviation between the angle and the preset angle is a i , where 0<i≤n, i and n are natural numbers, the deviation threshold of the device under test is b, and the precision index of the moving part is T ,and

If T≤0.5, and the device to be tested is a new device that has not been put into use, the data processing unit determines that the device to be tested meets the acceptance requirements of the new device.
The test platform according to claim 4, wherein, if 0.5<T≤1, and the device under test is an old device after repair, the data processing unit determines that the device under test meets the acceptance requirements of the old device .
The test platform according to claim 4, wherein, if 1<T≤2, and the device under test is an old device after maintenance, the data processing unit judges that the running accuracy of the device under test meets the requirements of the old device Acceptance requirements for a limited period of use.
The test platform according to claim 4, wherein, if T>2, and the device under test is an old device after repair, the data processing unit determines that the device under test does not meet the acceptance requirements.
The test platform according to claim 1, wherein the moving part moves from an initial position to the designated position, the test platform further comprises a first sensor and a second sensor arranged on the fixing frame, the The first sensor is set corresponding to the initial position, and the second sensor is set corresponding to the specified position; when the moving part reaches the initial position, the first sensor outputs a first electrical signal, and when the moving part reaches the initial position When the moving part reaches the designated position, the second sensor outputs a second electrical signal.
The test platform according to claim 8, further comprising a relay, the relay is electrically connected to the driving device, the relay turns off the driving device according to a first electrical signal sent by the first sensor, and is spaced apart from the first After a predetermined time, the driving device is started to rotate in the forward direction; the relay is turned off according to the second electrical signal sent by the second sensor, and the driving device is started to rotate in the reverse direction after a second predetermined time interval.
The test platform according to claim 1, wherein the device to be tested is a carrier device for lifting wafers, the moving part is a carrier platform that moves back and forth in a vertical direction, and the sensing unit is used for Sensing the distance between the carrying platform and the reference plane after the carrying platform moves to a designated position, so as to detect the flatness of the carrying platform.