Wafer testing apparatus, probe station thereof and alignment method therefor
By combining an image acquisition mechanism with a light reflection structure on the probe station, the problem of low alignment accuracy of the probe station was solved, achieving more efficient wafer testing.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SUZHOU EOULU SYSTEM INTEGRATION CO LTD
- Filing Date
- 2025-01-21
- Publication Date
- 2026-07-30
AI Technical Summary
In existing technologies, probe station alignment is not accurate and efficient, especially in integrated circuit manufacturing processes with small-sized chip electrodes, where accurate alignment is difficult to achieve.
The probe station design employs an image acquisition mechanism combined with a light reflection structure. The light reflection structure reflects the image of the wafer under test to the image acquisition mechanism, achieving automatic alignment control, and combined with the control system for precise alignment.
This achieves higher precision probe station alignment, improving the efficiency of wafer testing and the accuracy of probe placement.
Smart Images
Figure CN2025073547_30072026_PF_FP_ABST
Abstract
Description
Wafer testing equipment, probe station, and alignment method Technical Field
[0001] This invention relates to the field of semiconductor technology, and more particularly to a wafer testing device, its probe station, and alignment method. Background Technology
[0002] In the manufacturing process of integrated circuits (ICs), wafers are used as the carrier for manufacturing. After the semiconductor manufacturing process, multiple chips are formed on the wafer, and wafer-level testing is usually performed before they are diced into individual chips.
[0003] Probe stations are testing equipment used in the semiconductor industry, especially in the field of integrated circuit testing, where they are widely used. In wafer testing, probe stations are used to physically connect probes to the wafer, and then test signals are input and output through a test machine or instrument to ultimately test the electrical performance of the chips on the wafer.
[0004] In related technologies, a microscope is used to align the physical connection between a probe and a wafer. This involves obtaining the position of the probe tip and the position of the corresponding electrode on the chip. The probe or wafer is then moved based on this positional relationship to achieve the physical connection. This process is called probe station alignment. With the development of the semiconductor industry, integrated circuit manufacturing processes are becoming increasingly advanced, and the electrode size of chips in most advanced processes is shrinking, posing a greater challenge to achieving precise alignment with the probe station.
[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0006] In view of the problems in the prior art, the purpose of this invention is to provide wafer testing equipment, its probe station and alignment method, which overcomes the difficulties of the prior art and can improve the alignment accuracy of the probe station.
[0007] The first aspect of this disclosure provides a probe station for a wafer testing apparatus, comprising:
[0008] Film loading stage;
[0009] The probe card is located above the stage;
[0010] An image acquisition mechanism and a light reflection structure that cooperate with the image acquisition mechanism, wherein the image acquisition mechanism is located outside the slide stage, and the light reflection structure is located below the probe card and is installed with the probe card;
[0011] The light reflection structure is configured to reflect the image of the wafer under test below to the image acquisition mechanism on the outside. The image acquisition mechanism is configured to transmit the image of the wafer under test to the control system, so that the control system determines the position information of the wafer under test relative to the probe card based on the image of the wafer under test, and performs alignment control between the wafer stage and the probe card based on the position information.
[0012] In one embodiment, the light-reflecting structure includes:
[0013] The prism has an inclined design with its mirror surface and the stage surface facing outwards towards the image acquisition mechanism.
[0014] In one implementation, the prism is located outside the probe area of the probe card.
[0015] In one embodiment, the light reflection structure further includes an angle adjustment structure, which includes a pair of threaded holes in the probe card and a pair of screws that are screwed into the threaded holes. The arrangement direction of the pair of threaded holes is parallel to the optical path between the image acquisition mechanism and the light reflection structure, and the screws abut against the prism.
[0016] In one embodiment, the image acquisition mechanism includes:
[0017] A microscope, the lens of which is directed toward the light-reflecting structure;
[0018] A drive mechanism, mounted to the microscope, is configured to drive the microscope to move toward or away from the light-reflecting structure.
[0019] In one embodiment, the drive mechanism is a hybrid linear stepper motor.
[0020] In one embodiment, the probe station includes:
[0021] The plurality of image acquisition mechanisms arranged around the stage; and
[0022] Each of the multiple image acquisition mechanisms has a light reflection structure corresponding to one of them, and each light reflection structure is configured to reflect the image of the wafer under test to the corresponding image acquisition mechanism.
[0023] A second aspect of this disclosure provides an alignment method for a probe station of a wafer testing apparatus based on the above embodiments, comprising:
[0024] When the wafer to be tested is placed on the wafer stage, an image of the wafer to be tested is received from the image acquisition mechanism;
[0025] The image of the wafer under test is subjected to feature recognition. Based on the feature recognition results, the position information of the wafer under test relative to the probe card is determined. Based on the position information, the stage is controlled to move so that the wafer under test reaches the alignment position with the probe card.
[0026] In one embodiment, the step of performing feature recognition on the image of the wafer under test, determining the position information of the wafer under test relative to the probe card based on the feature recognition result, and controlling the movement of the wafer stage based on the position information includes at least one alignment process employing the following steps:
[0027] The similarity calculation is performed between the image of the wafer to be tested and a reference wafer image with feature patterns to obtain a similarity calculation result. The feature recognition result includes the similarity calculation result and the positional deviation between the feature patterns in the image of the wafer to be tested and the feature patterns in the reference wafer image.
[0028] The movement of the stage is controlled based on the positional deviation.
[0029] In one embodiment, when the probe station includes a plurality of image acquisition mechanisms arranged around the wafer stage and light reflection structures corresponding one-to-one with the plurality of image acquisition mechanisms, feature recognition is performed on the wafer image to be tested acquired by each of the image acquisition mechanisms until the wafer to be tested reaches the alignment position with the probe card based on the wafer image to be tested acquired by at least one image acquisition mechanism.
[0030] A third aspect of this disclosure provides a wafer testing apparatus, comprising:
[0031] The probe station of any of the above embodiments;
[0032] The control system is connected to the image acquisition mechanism and is configured to receive images of the wafer under test from the image acquisition mechanism, determine the position information of the wafer under test relative to the probe card by recognizing the images of the wafer under test, and control the stage to move according to the position information so that the wafer under test arrives at the alignment position with the probe card.
[0033] In this embodiment, the image acquisition mechanism is located outside the upper and lower relative areas of the probe card and the wafer stage. Therefore, the probe stage provided by this embodiment can effectively solve the problem of limited installation of the image acquisition mechanism, and the image acquisition mechanism is not obstructed by the probe card. Simultaneously, a light-reflecting structure with a smaller size relative to the image acquisition mechanism is disposed on the lower inner side of the probe card facing the wafer stage. This light-reflecting structure is responsible for acquiring the image of the wafer under test below and reflecting it outwards to the image acquisition mechanism, thereby achieving effective acquisition of the image of the wafer under test.
[0034] Using the probe station of this embodiment, the image acquisition mechanism and the light reflection structure work together to automatically acquire images of the wafer under test and automatically align the wafer and probe card based on these images. Therefore, the probe station of this embodiment enables real-time alignment, solving the technical problems of low accuracy and efficiency in offline alignment methods, achieving more precise alignment, improving the accuracy of probe placement, and increasing wafer testing efficiency through automatic alignment.
[0035] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description
[0036] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.
[0037] Figure 1 shows a perspective view of a probe station for a wafer testing apparatus according to an embodiment of the present disclosure, wherein the probe card is not shown.
[0038] Figure 2 shows a partial front view of a probe station for a wafer testing apparatus according to an embodiment of the present disclosure.
[0039] Figure 3 shows a three-dimensional view of the probe card in the probe station shown in Figure 2.
[0040] Figure 4 shows a partial cross-sectional view of the probe card shown in Figure 3.
[0041] Figure 5 shows a schematic diagram of the optical path between the image acquisition structure and the light reflection structure in the probe station shown in Figure 2.
[0042] Figure 6 shows a three-dimensional view of the image acquisition mechanism in the probe station shown in Figure 2.
[0043] Figure 7 illustrates the alignment method based on the probe station shown in Figure 2.
[0044] Figure label: Detailed Implementation
[0045] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0046] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.
[0047] In existing technologies, probe station alignment technology is divided into two types: offline alignment and real-time alignment. Offline alignment refers to using a microscope to align the probe station before automated testing to determine the relative position between the probe and the chip, followed by automated movement testing, during which no observation is performed. Real-time alignment, on the other hand, refers to performing probe station alignment in real time throughout the entire automated testing process.
[0048] In actual mass production testing, many electrodes need to be tested simultaneously. Probe cards are often used for testing. The probe card is connected to the testing machine or testing instrument, which creates an obstruction and makes it impossible to set up a microscope above the probe card. Therefore, most probe stations on the market currently use offline alignment technology, while real-time alignment technology has not yet been maturely applied on probe stations.
[0049] However, offline alignment technology is greatly affected by human factors, and the alignment accuracy of the probe station is not good.
[0050] This disclosure provides an automatic alignment method for a probe station, which can overcome the shortcomings of offline alignment technology.
[0051] As shown in Figures 1 and 2, the probe station used in wafer testing equipment includes:
[0052] Film stage 1;
[0053] The probe card 2 (not shown in Figure 1) is located above the stage 1;
[0054] The image acquisition mechanism 3 and the light reflection structure 4 that cooperate with the image acquisition mechanism 3 (as shown in Figure 3) are located on the outside of the stage 1, and the light reflection structure 4 is located below the probe card 2 and installed with the probe card 2.
[0055] The light reflection structure 4 is configured to reflect the image of the wafer under test below to the image acquisition mechanism 3 on the outside. The image acquisition mechanism 3 is configured to transmit the image of the wafer under test to the control system, so that the control system can determine the position information of the wafer under test relative to the probe card based on the image of the wafer under test, so as to perform alignment control between the wafer stage 1 and the probe card 2 based on the position information.
[0056] As shown in Figures 1 and 2, the wafer stage 1 is located within the wafer testing chamber 10a, and the image acquisition mechanism 3 is installed within the testing chamber 10a and located outside the wafer stage 1, i.e., the image acquisition mechanism 3 is located outside the vertically opposite areas of the probe card 2 and the wafer stage 1. Therefore, the probe station provided in this embodiment can effectively solve the problem of limited installation of the image acquisition mechanism 3, and the image acquisition mechanism 3 is not obstructed by the probe card 2. Simultaneously, a light-reflecting structure 4, which has a smaller size than the image acquisition mechanism 3, is disposed on the lower inner side of the probe card 2 facing the wafer stage 1. The light-reflecting structure 4 is responsible for acquiring the image of the wafer under test below and reflecting it outwards to the image acquisition mechanism 3, thereby achieving effective acquisition of the image of the wafer under test.
[0057] Using the probe station of this embodiment, the image acquisition mechanism 3 and the light reflection structure 4 cooperate to automatically acquire images of the wafer under test and automatically align the wafer under test with the probe card based on the images. Therefore, the probe station of this embodiment can achieve real-time alignment, solving the technical problems of low accuracy and low efficiency of offline alignment, achieving more accurate alignment, and improving wafer testing efficiency through automatic alignment.
[0058] In this embodiment of the disclosure, as shown in Figures 3 and 4, the light reflection structure 4 includes a prism 40. The mirror surface of the prism 40 is inclined to the stage surface of the slide stage 1 (as shown in Figure 2) and faces the outward image acquisition mechanism 3.
[0059] Referring to the optical path diagram shown in Figure 5, the mirror surface of the prism 40 is designed to be tilted, so that it can acquire the image of the wafer under test through the first optical path L1 and reflect it to the corresponding image acquisition mechanism 3 on the outside through the second optical path L2.
[0060] In practical applications, before alignment, the tilt angle of the prism 40 is properly configured so that it can not only capture a clear image of the wafer under test, but also effectively reflect it to the corresponding image acquisition mechanism 3.
[0061] Referring to Figure 4, the light reflection structure 4 also includes an angle adjustment structure 41. The angle adjustment structure 41 includes a pair of threaded holes 41a located in the probe card 2 and a pair of screws 410 that are screwed into the threaded holes 41a. The arrangement direction of these threaded holes 41a is parallel to the optical path between the image acquisition mechanism 3 and the light reflection structure 4. The screws 410 abut against the prism 40. Using this angle adjustment structure 41, by turning one end of the screw 410 in one rotational direction to press one end of the prism 40 downwards, and turning the other end of the screw 410 in the opposite direction to move it upwards, the other end of the prism 40 tilts upwards, thereby adjusting the tilt angle of the prism 40 and calibrating it.
[0062] In this embodiment, prism 40 is only one example. In other embodiments, other mirrors may be used for the light reflecting structure 4, which are not limited here.
[0063] As shown in Figure 3, the probe card 2 has a probe area s1, which is used to install probes. The light reflection structure 4 is located outside the probe area s1. Therefore, the light reflection structure 4 will not affect the installation of probes in the probe area s1. Moreover, the outer area of the probe card 2 is effectively utilized to arrange the light reflection structure 4. There will be no further improvement to the probe card 2, and the manufacturing cost is low.
[0064] As shown in Figure 4, the light reflection structure 4 includes a prism 40. The prism 40 is relatively small in size, occupies little space, and has low manufacturing and installation costs.
[0065] In this embodiment of the disclosure, as shown in Figures 1 and 6, the image acquisition mechanism 3 includes an optical image acquisition system, such as a camera or microscope 30, whose lens is aligned with the reflective surface of the prism 40 (as shown in Figure 4). Referring to Figure 5, the image of the wafer under test captured by the prism 40 is reflected to the microscope 30 along the second optical path L2.
[0066] Microscope 30 is a charge-coupled device (CCD) microscope, which can convert the image of the wafer under test into an electrical signal. Microscope 30 establishes a communication connection with the control system (not shown in the figure), and transmits the acquired image of the wafer under test to the control system in real time. The control system then makes alignment decisions based on the image of the wafer under test.
[0067] In this embodiment of the disclosure, as shown in Figures 1 and 6, the image acquisition mechanism 3 further includes a drive mechanism 31 mounted to the microscope 30. The drive mechanism 31 is used to drive the microscope 30 to move toward or away from the corresponding light reflection structure 4 (not shown in Figure 6).
[0068] As shown in Figure 5, during the alignment process of the probe station, the relative distance between the probe card 2 and the stage 1 in the vertical direction is adjusted so that the image of the wafer under test captured by the light reflection structure 4 can be reflected into the microscope 30. The control drive mechanism 31 drives the microscope 30 to move towards or away from the corresponding light reflection structure 4 along the direction of the second optical path L2, that is, to adjust the length of the second optical path L2. This is actually a focusing process to ensure the clarity of the captured image of the wafer under test, thereby ultimately improving the alignment accuracy.
[0069] As shown in Figures 1 and 6, the image acquisition mechanism 3 is installed on the inner wall of the test chamber 10a, specifically through the drive mechanism 31.
[0070] In this embodiment, the drive mechanism 31 is selected from linear drive mechanisms such as linear motors or linear cylinders, for example, a hybrid linear stepper motor. In another embodiment, the drive mechanism 31 may also include a rotary motor and a transmission mechanism, the transmission mechanism being used to convert the rotational motion output by the rotary motor into linear motion, such as a lead screw drive mechanism, which is not limited here.
[0071] In this embodiment of the disclosure, as shown in FIG1, the probe station includes:
[0072] The plurality of image acquisition mechanisms 3 arranged around the stage 1; and
[0073] Each of the multiple image acquisition mechanisms 3 has a light reflection structure 4 that corresponds to one of them, and each light reflection structure 4 is configured to reflect the image of the wafer under test to the corresponding image acquisition mechanism 3.
[0074] In this configuration, each image acquisition unit 3 can acquire an image of the wafer under test at its corresponding location, with different graphic positions appearing in the images acquired by different acquisition units 3. This allows the control system to align the wafer and probe card based on the images of the wafer under test at different locations, resulting in higher alignment accuracy.
[0075] As shown in Figure 1, this embodiment includes three image acquisition mechanisms 3 and three corresponding light reflection structures 4. This is an example; in other embodiments, multiple image acquisition mechanisms and corresponding light reflection structures can be selected as needed.
[0076] This disclosure also provides a wafer testing apparatus, which includes a probe station and a control system according to any of the above embodiments.
[0077] The control system is connected to the image acquisition mechanism and is configured to receive images of the wafer under test from the image acquisition mechanism, determine the position information of the wafer under test relative to the probe card by recognizing the image of the wafer under test, and control the stage to move according to the position information so that the wafer under test arrives at the alignment position with the probe card, which corresponds to the probe pin position.
[0078] In this embodiment, the control system stores a corresponding program responsible for image recognition and alignment, as well as sending control commands to the wafer stage, causing the wafer stage to move in response to the control commands.
[0079] Therefore, the wafer-side device using this embodiment can achieve automatic alignment of the probe station.
[0080] The present disclosure provides an alignment method for a probe station based on the above embodiments, as shown in FIG7, which includes, but is not limited to, the following steps:
[0081] Step 710: When the wafer to be tested is placed on the wafer stage, an image of the wafer to be tested is received from the image acquisition mechanism;
[0082] Step 720: Perform feature recognition on the image of the wafer under test, determine the position information of the wafer under test relative to the probe card based on the feature recognition result, and control the stage to move according to the position information so that the wafer under test reaches the alignment position with the probe card, which corresponds to the pin position of the probe on the probe card.
[0083] Using the aforementioned probe station, an image recognition scheme is employed to align the wafer under test with the probe station, thereby achieving precise alignment.
[0084] In one embodiment, a series of repeating periodic structures are formed on the wafer under test. The periodic structure is called a grating structure, such as a photoresist grating structure. The periodic structure can be a die structure.
[0085] Therefore, a similar periodic structure can be identified beforehand on a reference wafer corresponding to the wafer to be tested, and a region with a characteristic pattern can be defined within it. This characteristic pattern has obvious features within the periodic structure; for example, the patterns at other locations in the periodic structure are different from or dissimilar to the characteristic pattern. The region with the characteristic pattern serves as a reference wafer image. For example, the region with the characteristic pattern can be the starting position of the periodic structure.
[0086] In this case, feature recognition is performed on the image of the wafer under test, the position information of the wafer under test relative to the probe card is determined based on the feature recognition result, and the movement of the wafer stage is controlled based on the position information. Specifically, this includes at least one alignment process using the following steps:
[0087] The similarity calculation is performed between the image of the wafer to be tested and a reference wafer image with feature patterns to obtain the similarity calculation result. The feature recognition result includes the similarity calculation result and the positional deviation between the feature patterns in the image of the wafer to be tested and the feature patterns in the reference wafer image.
[0088] The movement of the stage is controlled based on the positional deviation.
[0089] In this embodiment, the reference wafer image can be an image of a periodic structure on the wafer, showing feature patterns. The similarity can include shape similarity and positional similarity. If the shape similarity calculation shows the presence of feature patterns, the positional information of the feature patterns in the wafer image under test is further determined, and positional similarity is calculated between this positional information and the positional information of the feature patterns in the reference wafer image to determine the positional deviation. Then, the stage movement is controlled based on the positional deviation.
[0090] In the specific implementation process, the above similarity calculation and control of the stage movement are repeated until the set end condition is reached. Based on the set end condition, the alignment position of the wafer under test with the probe card is determined.
[0091] In one implementation, the stage is moved according to the position deviation obtained each time. When the position deviation is within the set range, it is considered that the image of the wafer to be tested is approximately coincident with the image of the reference wafer, and at this time, the set termination condition is met.
[0092] In another implementation, when the set number of repetitions is met, the alignment process is considered to have reached the set termination condition and is terminated. This set termination condition balances testing efficiency and alignment accuracy.
[0093] In an exemplary embodiment, the movement of the wafer stage is controlled according to the position deviation. Specifically, a position compensation value is calculated based on the position deviation, and this position compensation value is used as a compensation value for the position deviation. Subsequently, the wafer stage is controlled to move according to the position compensation value.
[0094] In one embodiment, controlling the movement of the stage based on the positional deviation includes:
[0095] The position compensation value at the current moment is calculated based on the position deviation, and the wafer stage is moved according to the position compensation value. After the movement, the probe card is controlled to perform a pin piercing test on the current periodic structure in the wafer under test.
[0096] The stage is controlled to move to the next periodic structure of the current periodic structure, and then the stage is moved according to the position compensation value at the current time. After the movement, the next periodic structure is used as the current periodic structure, and the probe card is controlled to perform a pin piercing test on the current periodic structure in the wafer under test.
[0097] Return to the control and move the stage to the next periodic structure of the current periodic structure until the cumulative number of compensations for the current position compensation value reaches the target number of times;
[0098] When the cumulative number of compensations for the current position compensation value reaches the target number, the stage is controlled to move to a new periodic structure and return to the similarity calculation of the image of the wafer under test and the reference wafer image with feature patterns to obtain the similarity calculation result. The feature recognition result includes the similarity calculation result and the positional deviation between the feature patterns in the image of the wafer under test and the feature patterns in the reference wafer image.
[0099] In this embodiment, after obtaining the position compensation value at the current moment and performing a pin test on the current periodic structure, the position compensation value at the current moment is used as the position compensation value for the movement and alignment of a target number of periodic structures starting from the current moment. After the movement and alignment of the target number of periodic structures, the position compensation value is recalculated. This embodiment can improve wafer testing efficiency.
[0100] For example, the target quantity could be the number of periodic structures in each row or the number of periodic structures in each column. For instance, if the stage moves along the row direction, the position compensation value obtained when aligning the first periodic structure can be used to compensate for the alignment movement of all periodic structures in the current row, and the position compensation value is recalculated after a row change.
[0101] For scanning alignment and compensation along the column direction, please refer to the scanning alignment and compensation along the row direction described above, which will not be repeated here.
[0102] In this embodiment of the disclosure, when the probe station includes multiple image acquisition mechanisms located outside the wafer stage, feature recognition is performed on the image of the wafer under test acquired by each of the image acquisition mechanisms until the wafer under test reaches the alignment position with the probe card based on the image of the wafer under test acquired by at least one image acquisition mechanism. This alignment position corresponds to the pin insertion position of the probe on the probe card. After reaching the alignment position, the probe is controlled to perform pin insertion, effectively improving the accuracy of pin insertion positioning.
[0103] In this embodiment, once the image of the wafer under test captured by any one image acquisition mechanism reaches the alignment position, the alignment of the wafer under test and the probe station is finally determined. This embodiment, by setting up multiple image acquisition mechanisms, can expand the image capture range of the wafer under test, thereby significantly improving alignment efficiency.
[0104] For example, in conjunction with the above embodiments, when multiple positional deviations are determined based on multiple image acquisition mechanisms at the current moment, the image acquisition mechanism with the smallest positional deviation can be selected, and the stage movement can continue to be controlled based on this smallest positional deviation. In this case, the smallest positional deviation indicates that alignment can be achieved in a short time without significantly moving the stage.
[0105] For example, when multiple position deviations are obtained at the current moment, the average value of the position deviation is calculated, and the stage movement displacement at the next moment, including the movement direction and movement distance, is determined based on the average value of the position deviation.
[0106] In other embodiments of this disclosure, before placing the wafer under test on the wafer stage, another image acquisition mechanism can be used above the probe card to capture probe images, thereby determining the probe position. Then, when the wafer under test is placed on the wafer stage and aligned, the difference between the wafer images captured by the multiple image acquisition mechanisms located on the outer side and the probe images captured by the image acquisition mechanism above is calculated. Based on the current position of the wafer stage and the aforementioned difference, the probe position deviation is calculated, and a position compensation value is calculated. The probe stage is then moved according to this position compensation value.
[0107] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.
Claims
1. A probe station for a wafer testing equipment, characterized in that, include: Film stage (1); The probe card (2) is located above the slide stage (1); An image acquisition mechanism (3) and a light reflection structure (4) that cooperates with the image acquisition mechanism (3). The image acquisition mechanism (3) is located outside the stage (1), and the light reflection structure (4) is located below the probe card (2) and is installed with the probe card (2). The light reflection structure (4) is configured to reflect the image of the wafer under test below to the image acquisition mechanism (3) on the outside. The image acquisition mechanism (3) is configured to transmit the image of the wafer under test to the control system, so that the control system determines the position information of the wafer under test relative to the probe card (2) based on the image of the wafer under test, so as to perform alignment control between the wafer stage (1) and the probe card (2) based on the position information.
2. The probe station for wafer testing equipment according to claim 1, characterized in that, The light-reflecting structure (4) includes: The prism (40) has its mirror surface inclined to the stage surface of the slide stage (1) and facing the image acquisition mechanism (3) to the outside.
3. The probe station for wafer testing equipment according to claim 2, characterized in that, The prism (40) is located outside the probe area (s1) of the probe card (2).
4. The probe station for wafer testing equipment according to claim 2, characterized in that, The light reflection structure (4) further includes an angle adjustment structure (41), which includes a pair of threaded holes (41a) located in the probe card (2) and a pair of screws (410) that form a screw-fit with the threaded holes (41a). The arrangement direction of the pair of threaded holes (41a) is parallel to the optical path between the image acquisition mechanism (3) and the light reflection structure (4), and the screws (410) abut against the prism (40).
5. The probe station for wafer testing equipment according to claim 1, characterized in that, The image acquisition mechanism (3) includes: A microscope (30) with its lens facing the light-reflecting structure (4); A drive mechanism (31), mounted to the microscope (30), is configured to drive the microscope (30) to move toward or away from the light-reflecting structure (4).
6. The probe station for wafer testing equipment according to claim 5, characterized in that, The drive mechanism (31) is a hybrid linear stepper motor.
7. The probe station for wafer testing equipment according to claim 1, characterized in that, The probe station includes: The plurality of image acquisition mechanisms (3) arranged around the stage (1); and Each of the multiple image acquisition mechanisms (3) has a light reflection structure (4) that is configured to reflect the image of the wafer under test to the corresponding image acquisition mechanism (3).
8. A method for aligning a probe station for a wafer testing apparatus as described in claim 1, characterized in that, include: When the wafer to be tested is placed on the stage (1), an image of the wafer to be tested is received from the image acquisition mechanism (3); The image of the wafer under test is subjected to feature recognition. The position information of the wafer under test relative to the probe card (2) is determined according to the feature recognition result. The wafer stage (1) is moved according to the position information so that the wafer under test reaches the alignment position with the probe card (2).
9. The alignment method according to claim 8, characterized in that, The process of performing feature recognition on the image of the wafer under test, determining the position information of the wafer under test relative to the probe card (2) based on the feature recognition result, and controlling the movement of the wafer stage (1) based on the position information includes at least one alignment process employing the following steps: The similarity calculation is performed between the image of the wafer to be tested and a reference wafer image with feature patterns to obtain a similarity calculation result. The feature recognition result includes the similarity calculation result and the positional deviation between the feature patterns in the image of the wafer to be tested and the feature patterns in the reference wafer image. The movement of the stage (1) is controlled according to the positional deviation.
10. The alignment method according to claim 8, characterized in that, The step of controlling the movement of the stage (1) based on the positional deviation includes: The position compensation value at the current moment is calculated based on the position deviation, and the wafer stage (1) is moved according to the position compensation value. After the movement, the probe card is controlled to perform a pin test on the current periodic structure in the wafer under test. The stage (1) is controlled to move to the next periodic structure of the current periodic structure. Then, the stage (1) is moved according to the position compensation value at the current time. After the movement, the next periodic structure is used as the current periodic structure. The probe card is then controlled to perform a pin piercing test on the current periodic structure in the wafer under test. Return to the control of the stage (1) to move to the next periodic structure of the current periodic structure until the cumulative number of compensations for the current position compensation value reaches the target number of times; When the cumulative number of compensations for the current position compensation value reaches the target number, the stage (1) is controlled to move to a new periodic structure and return to the similarity calculation of the image of the wafer to be tested and the reference wafer image with feature patterns to obtain the similarity calculation result. The feature recognition result includes the similarity calculation result and the positional deviation between the feature patterns in the image of the wafer to be tested and the feature patterns in the reference wafer image.
11. The alignment method according to claim 8, characterized in that, When the probe station includes a plurality of image acquisition mechanisms (3) arranged around the wafer stage (1) and a light reflection structure (4) corresponding one-to-one with the plurality of image acquisition mechanisms (3), feature recognition is performed on the image of the wafer under test acquired by each of the image acquisition mechanisms (3) until the wafer under test reaches the alignment position with the probe card (2) based on the image of the wafer under test acquired by at least one image acquisition mechanism (3).
12. A wafer testing device, characterized in that, include: The probe station according to any one of claims 1-7; The control system is connected to the image acquisition mechanism (3) and is configured to receive the image of the wafer under test from the image acquisition mechanism (3), determine the position information of the wafer under test relative to the probe card (2) by recognizing the image of the wafer under test, and control the stage (1) to move according to the position information so that the wafer under test arrives at the alignment position with the probe card (2).