Radio frequency probe full-automatic regulation and control method and system based on scattering parameter change

Abstract

The invention provides a full-automatic radio frequency probe regulation and control method and system based on scattering parameter variation, and the method comprises the steps: obtaining the scattering parameters of three contacts of GSG relative to three contact pads in real time in the process that a probe moves and aligns relative to a wafer electrode touch panel; according to the polar coordinate graph position of the scattering parameter, leveling operation of the probe is executed, specifically, according to the polar coordinate graph position of the scattering parameter, the included angle theta between the connecting line of three contacts of the GSG and the plane where the electrode touch panel is located is regulated and controlled, and the connecting line of the three contacts of the GSG is made to be parallel to the plane where the electrode touch panel is located; and executing the alignment operation of the three-dimensional position of the probe according to the change of the real part value of the scattering parameter, namely regulating and controlling the positions of the three contacts of the GSG relative to the XYZ axes of the three contact pads according to the change of the real part value of the scattering parameter, so that the three contacts of the GSG are respectively contacted with the three contact pads. According to the invention, automatic fine regulation and control of the probe in four directions of X, Y, Z and theta are realized, so that the alignment precision, repeatability and measurement accuracy are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor radio frequency microwave testing, and relates to a full-automatic control method and system of a radio frequency probe based on scattering parameter changes. Background Art

[0002] Precise wafer testing technology is mainly based on the parameter measurement and precision calibration procedures of the probe station, which is a key step in the design and debugging of integrated circuits (ICs). In the semiconductor industry and related research fields, wafer test probe stations are currently mature tools for testing circuits and devices on wafers, and manual probe stations are more commonly used.

[0003] In actual testing, especially in the field of metrology, more emphasis is placed on measurement accuracy, versatility and scalability. On the one hand, when using a manual probe station, the operator needs to observe the contour of the probe head through a microscope to infer the position of the tip GSG contact and manually align the probe with the chip contact pad. However, different operators have certain differences in their judgment of the probe head contour, and during the on-wafer measurement of the chip, due to long-term use of the probe and frequent stress on the probe tip, fatigue of the probe tip may occur, resulting in certain deformation, causing the position of the probe head contour relative to the probe tip GSG contact to change. Therefore, between the new probe and the old probe, even if the same operator observes that the probe head contour is completely aligned at the same position, the position of the probe tip contact will be different. In addition, depending on the probe manufacturer and model, the relative position between the probe head contour and the probe tip also varies significantly.

[0004] On the other hand, in traditional test systems, the probe tilt angle is determined by the operator adjusting the probe tip through a microscope and observing the footprint left by the probe tip on the leveling sheet. When using a GSG probe, the operator adjusts the tilt angle until three symmetrical and identical footprints are obtained simultaneously on the leveling sheet. However, the angle range in which all probe tips can effectively contact the pad varies depending on the probe glide, and the accuracy of the adjustment depends largely on the change in probe glide, while the contact pad and probe tip are often not clear enough under the microscope, affecting the judgment. For the above reasons, the current metrology method based on the manual probe station has problems such as unsatisfactory alignment accuracy, limited repeatability, and inaccurate measurement results.

[0005] Therefore, how to provide a fully automatic control method and system for a radio frequency probe with high alignment accuracy, repeatability and measurement accuracy is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] In view of this, the present invention proposes a fully automatic control method and system for a radio frequency probe based on changes in scattering parameters. The radio frequency signal is detected and analyzed during the contact process between the probe and the chip, and a probe position recognition model and a probe tilt precision adjustment model are established, so that the probe can be automatically and finely controlled in the four directions of X, Y, Z and θ to improve the alignment accuracy, repeatability and measurement accuracy.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The present invention discloses a fully automatic control method for a radio frequency probe based on a change in scattering parameters, wherein three contacts of the probe GSG are used to simultaneously contact three contact pads of a wafer electrode contact plate to implement wafer testing; the method comprises the following steps:

[0009] In the process of moving and aligning the probe relative to the wafer electrode contact plate, scattering parameters of the three GSG contact points relative to the three contact pads are obtained in real time;

[0010] Performing a leveling operation of the probe according to the position of the polar coordinate diagram of the scattering parameter includes: adjusting the angle θ between the line connecting the three contacts of the GSG and the plane where the electrode touch plate is located according to the position of the polar coordinate diagram of the scattering parameter, so that the line connecting the three contacts of the GSG is parallel to the plane where the electrode touch plate is located;

[0011] The three-dimensional position alignment operation of the probe is performed according to the change of the real value of the scattering parameter, including: adjusting the XYZ axis positions of the three contacts of the GSG relative to the three contact pads according to the change of the real value of the scattering parameter, so that the three contacts of the GSG are in contact with the three contact pads respectively.

[0012] Preferably, the leveling operation of the probe is performed according to the amplitude change of the scattering parameter, including: judging in real time whether the amplitude of the scattering parameter is 1 and is located in the second quadrant of the polar coordinate diagram; if so, the line connecting the three contacts of GSG is parallel to the plane where the wafer electrode contact plate is located, and the leveling operation is ended.

[0013] Preferably, the three-dimensional position alignment operation of the probe is performed according to the change of the real value of the scattering parameter, including: real-time judgment on whether a steep increase signal appears in the real value of the scattering parameter, and the change amplitude of the steep increase signal is greater than a preset value. If so, the three contacts of the GSG are in contact with the three contact pads respectively, thereby ending the three-dimensional position alignment operation.

[0014] Preferably, the control coordinate system is: the Z axis is perpendicular to the electrode touch plate direction, and the XOY plane is parallel to the plane where the electrode touch plate is located; the leveling operation of the probe is performed according to the amplitude change of the scattering parameter, including:

[0015] S11: adjusting the probe to an initial position, wherein the initial position is that the three contacts of the GSG are located in the positive direction of the Z axis of the electrode contact plate and are located in a corresponding position range relative to the three contact pads in the XOY plane;

[0016] S12: Control the probe to move gradually downward along the Z axis according to the preset step distance, and record the scattering parameter amplitude in real time. If the scattering parameter amplitude is 1 and is located in the second quadrant of the polar coordinate diagram, it is recorded as the first state and enters S13; if the scattering parameter amplitude is less than 1, it is recorded as the second state and enters S14; if the scattering parameter amplitude is 1 and is located in the fourth quadrant of the polar coordinate diagram, it is recorded as the third state and enters S15;

[0017] S13: Tilt the probe according to a preset step angle until the scattering parameter enters the second state, record the angle θ, and record it as A1; Tilt the probe in the opposite direction according to the preset step angle until the scattering parameter enters the second state again, record the angle θ, and record it as A2, and enter S16;

[0018] S14: Determine the side where the contact point that is not in contact with the contact pad is located, tilt the probe along the direction of the side according to a preset step angle, until the scattering parameter enters the first state, record the angle θ, and record it as A1; continue to tilt the probe according to the preset step angle until the scattering parameter enters the second state again, record the angle θ, and record it as A2, and enter S16;

[0019] S15: Determine the number of contact points that are not in contact with the contact pad, if it is 0, return to S12; if it is 1, return to S14;

[0020] S16: Setting the target angle to the average value between A1 and A2, and adjusting the angle θ between the connection line of the three contacts of GSG and the plane where the electrode contact plate is located to the target angle, thereby completing the leveling operation.

[0021] Preferably, the alignment operation of the initial position in S11 is performed according to the change of the real part value of the scattering parameter.

[0022] Preferably, the control coordinate system is: the Z axis is perpendicular to the electrode contact plate direction, the XOY plane is parallel to the plane where the electrode contact plate is located, the X axis is the arrangement direction of the three contact pads, and the Y axis is the extension direction of the three contact pads on the wafer electrode contact plate; the alignment operation of the three-dimensional position of the probe is performed according to the change of the real part value of the scattering parameter, including:

[0023] Adjusting the probe to an initial height, wherein the initial height is a fixed distance between the probe and the wafer electrode contact plate;

[0024] Control the probe to move stepwise along the Y axis at the initial height according to a preset step distance, and control the probe to move downward along the Z axis by the fixed distance value after each step is completed, so that the contact point contacts the wafer electrode contact plate, and record the scattering parameters until the real part value of the scattering parameter shows the steep increase signal;

[0025] The probe is controlled to move stepwise along the X-axis at the initial height according to a preset step distance. After each step is completed, the probe is controlled to move downward along the Z-axis by the fixed distance value so that the contact point contacts the wafer electrode contact plate, and the scattering parameters are recorded until the real part value of the scattering parameter shows the steep increase signal.

[0026] Preferably, a vector network analyzer is used to obtain scattering parameters of the three GSG contacts relative to the three contact pads in real time; and the method further includes a calibration step of the vector network analyzer:

[0027] Use calibration equipment to measure the actual S parameters of the DUT;

[0028] Calculating S parameters of an equivalent model of a device under test in the vector network analyzer;

[0029] The residuals between the measured S parameters and the equivalent model S parameters are minimized using a nonlinear least squares algorithm.

[0030] The present invention also discloses a radio frequency probe fully automatic control system according to the radio frequency probe fully automatic control method based on scattering parameter changes, comprising: a probe, a vector network analyzer, a control module, a probe GSG rotation angle fine-tuning system, a probe three-dimensional position control system and a wafer chuck; wherein,

[0031] The vector network analyzer is connected to the probe and is used to obtain scattering parameters of the three GSG contacts relative to the three contact pads in real time during the process of the probe moving and aligning relative to the wafer electrode contact plate;

[0032] The control module is connected to the vector network analyzer, and is used to generate a leveling operation instruction of the probe according to the position of the polar coordinate diagram of the scattering parameters, including: generating a leveling operation instruction for adjusting the angle θ between the connection line of the three contacts of GSG and the plane where the electrode touch pad is located according to the position of the polar coordinate diagram of the scattering parameters, so that the connection line of the three contacts of GSG is parallel to the plane where the electrode touch pad is located; and generating an alignment operation instruction for the three-dimensional position of the probe according to the change of the real value of the scattering parameters, including: generating an alignment operation instruction for adjusting the position of the three contacts of GSG relative to the XYZ axes of the three contact pads according to the change of the real value of the scattering parameters, so that the three contacts of GSG are respectively in contact with the three contact pads;

[0033] The probe GSG rotation angle fine-tuning system is used to receive and execute the leveling operation instruction;

[0034] The probe three-dimensional position control system is used to receive and execute the alignment operation instruction;

[0035] The wafer chuck is used to fix the wafer electrode contact plate.

[0036] Preferably, it also includes a microscope; the microscope is used to display the observation position of the probe relative to the wafer electrode contact plate; in the step of performing the leveling operation of the probe according to the amplitude change of the scattering parameter, the probe is adjusted to an initial position in combination with the observation position, and the initial position is that the three contacts of the GSG are located in the positive direction of the Z axis of the electrode contact plate and in the corresponding position range relative to the three contact pads in the XOY plane; the angle θ is regulated based on the initial position.

[0037] Preferably, it also includes a microscope; the microscope is used to display the observation position of the probe relative to the wafer electrode touch plate; in the step of performing the alignment operation of the three-dimensional position of the probe according to the change of the real value of the scattering parameter, the probe is adjusted to an initial height in combination with the observation position, and the initial height is a fixed distance value for the vertical distance between the probe and the wafer electrode touch plate; based on the initial height, the positions of the three contacts of the GSG relative to the XYZ axes of the three contact pads are regulated.

[0038] It can be seen from the above technical solution that, compared with the prior art, the beneficial effects of the present invention include:

[0039] The present invention significantly enhances the accuracy of the test result by precisely adjusting the position of the probe in the X, Y and Z directions and optimizing the parallelism between the probe GSG contact and the surface of the wafer chip.

[0040] The present invention combines optical positioning and electrical control technology to ensure the accuracy of the probe position and the high repeatability of the operation, which is of great significance for improving the yield rate of the chip and reducing the manufacturing cost.

[0041] The present invention provides an innovative solution for the field of semiconductor chip testing to achieve precise control of the position of a probe on a wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without creative work.

[0043] Figure 1A flow chart of a method for fully automatic control of a radio frequency probe based on changes in scattering parameters provided by an embodiment of the present invention;

[0044] Figure 2 A schematic diagram of different contact states between a probe and a contact point provided by an embodiment of the present invention;

[0045] Figure 3 A typical polar coordinate diagram of scattering parameters corresponding to different contact states provided by an embodiment of the present invention;

[0046] Figure 4 A graph showing the variation of the real part of the scattering parameter S11 during the process of the probe approaching the chip surface provided by an embodiment of the present invention;

[0047] FIG5( a ) is a YOZ plane schematic diagram of a probe three-dimensional position alignment operation provided by an embodiment of the present invention;

[0048] FIG5( b ) is a schematic diagram of an XOY plane of a probe three-dimensional position alignment operation provided by an embodiment of the present invention;

[0049] Figure 6 A schematic diagram of specific steps of executing the fully automatic control method of a radio frequency probe provided by an embodiment of the present invention;

[0050] Figure 7 This is an architecture diagram of the fully automatic control system of the radio frequency probe provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] like Figure 1 As shown, the first aspect of the embodiment of the present invention provides a fully automatic control method of a radio frequency probe based on a change in scattering parameters, wherein three contacts of the probe GSG are used to simultaneously contact three contact pads of a wafer electrode contact plate to implement wafer testing; the method comprises the following steps:

[0053] During the process of the probe moving and aligning with the wafer electrode contact plate, the scattering parameters of the three GSG contact points relative to the three contact pads are obtained in real time;

[0054] Performing a probe leveling operation according to the position of the polar coordinate diagram of the scattering parameter includes: adjusting the angle θ between the line connecting the three contacts of the GSG and the plane where the electrode touch plate is located according to the position of the polar coordinate diagram of the scattering parameter, so that the line connecting the three contacts of the GSG is parallel to the plane where the electrode touch plate is located;

[0055] The three-dimensional position alignment operation of the probe is performed according to the change of the real value of the scattering parameter, including: adjusting the XYZ axis positions of the three GSG contacts relative to the three contact pads according to the change of the real value of the scattering parameter, so that the three GSG contacts are in contact with the three contact pads respectively.

[0056] The principle of the leveling operation in the embodiment is described as follows:

[0057] There are three typical situations when the three contacts of the probe GSG contact the chip, such as Figure 2 As shown in the figure, when the angle θ between the straight line where the three contacts GSG of the probe are located and the contact surface of the chip is large, only one G contact point is in contact with the chip; when θ is small, there may be two contacts, one G and one S, in contact with the chip, and the other G contact is suspended in the air; when θ is 0, all three contacts, two G and one S, are in contact with the chip, and the probe is leveled.

[0058] In order to distinguish the above three contact situations, a short-circuit contact plate can be used to simulate the wafer chip. The contact between the probe and the chip can be equivalent to the contact between the probe and the short-circuit contact plate. The equivalent circuit diagram of a G contact point contacting the chip is two capacitors in parallel; the equivalent circuit diagram of a G and an S contacting the chip is a capacitor and an inductor in parallel; the equivalent circuit diagram of two G and one S contact points contacting the chip is two inductors in parallel. Figure 3 As shown in FIG. 1 , typical polar coordinate diagrams (the horizontal axis is the real part and the vertical axis is the imaginary part) of the corresponding scattering parameters obtained from the vector network analyzer VNA under different contact conditions. The numbers in the figure represent the number of probe tips (G or S) in contact.

[0059] When the three GSG contacts of the probe are in good contact with the electrodes of the short-circuit contact plate, two parallel loops are formed between each ground contact G and the signal contact S, so there should be inductance between the two, and the corresponding scattering parameter amplitude |S11| is approximately 1, which is in the upper left area of ​​the Smith diagram;

[0060] When only one G contact of the three contacts of the probe GSG is in good contact with the short-circuit contact plate electrode, or none of the three contacts are in good contact with the short-circuit contact plate electrode, no loop is formed between each ground contact G and the signal contact S, and there should be an equivalent capacitance between the G contact and the S contact. The corresponding scattering parameter amplitude |S11| is approximately 1, which is in the lower right area of ​​the Smith diagram.

[0061] When only the S contact and one G contact of the three contacts of the probe's GSG are in good contact with the short-circuit contact plate electrode, a loop is formed between the contact contact G and the signal contact S, corresponding to the existence of an equivalent inductance, while no loop is formed between the other contact G and the signal contact S, corresponding to the existence of an equivalent capacitance, the inductance and capacitance are connected in parallel to produce resonance in a wide frequency band, and the corresponding scattering parameter amplitude |S11| is mostly less than 1 and is in the inner area of ​​the Smith diagram.

[0062] Therefore, based on the characteristics of the S11 parameter, the actual contact quantity and contact degree of the three contacts can be determined by analyzing the change pattern of the S11 parameter when the three GSG contacts at the probe tip are in contact with the contact plate.

[0063] The principle of the alignment operation in the embodiment is described:

[0064] When the measured scattering parameters suddenly change, it indicates that the probe is in contact with the chip. Therefore, fine control of the Z-axis direction can be regulated by observing the scattering parameters. Figure 4 Figure 2 shows an Infinity probe approaching an ISS at a speed of 100 nm / s within a distance of 50 μm.

[0065] 101-190C calibration process, the horizontal axis represents the total number of points recorded during the probe movement, and the vertical axis represents the real part value of the scattering parameter S11 corresponding to each recording point.

[0066] It can be observed that when the probe is far away from the chip, the obtained S11 signal is almost constant; when the probe tip approaches the chip surface, it can be seen that the S11 signal begins to increase; and when the probe tip contacts the chip surface, the S11 signal suddenly increases sharply and reaches a very high value. After this node, continue to fine-tune the pressure probe in the Z-axis direction to ensure good contact between the probe tip and the chip. When the probe leaves the chip surface and is gradually recovered, a behavior completely opposite to the process of the probe tip approaching the chip surface can be observed. Therefore, the relationship between the S11 signal mutation process and the distance traveled by the corresponding probe tip in the Z-axis direction when the probe tip contacts and leaves the chip surface can provide a basis for establishing an automatic control mechanism for the probe position using VNA real-time feedback.

[0067] In one embodiment, the probe leveling operation is performed according to the amplitude change of the scattering parameter, including: judging in real time whether the amplitude of the scattering parameter is 1 and is located in the second quadrant of the polar coordinate diagram; if so, the line connecting the three contacts of GSG is parallel to the plane where the wafer electrode contact plate is located, and the leveling operation is ended.

[0068] In one embodiment, the three-dimensional position alignment operation of the probe is performed according to the change of the real part value of the scattering parameter, including: real-time judgment on whether a steep increase signal appears in the real part value of the scattering parameter, and the change amplitude of the steep increase signal is greater than a preset value. If so, the three contacts of the GSG are in contact with the three contact pads respectively, thereby ending the three-dimensional position alignment operation.

[0069] In one embodiment, the control coordinate system is: the Z axis is perpendicular to the electrode touch plate direction, and the XOY plane is parallel to the plane where the electrode touch plate is located; the probe leveling operation is performed according to the amplitude change of the scattering parameter, including:

[0070] S11: Adjust the probe to the initial position, where the three contacts of GSG are located in the positive direction of the Z axis of the electrode touch plate and in the corresponding position range relative to the three contact pads in the XOY plane;

[0071] S12: Control the probe to move gradually downward along the Z axis according to the preset step distance, and record the scattering parameter amplitude in real time. If the scattering parameter amplitude is 1 and is located in the second quadrant of the polar coordinate diagram, it is recorded as the first state and enters S13; if the scattering parameter amplitude is less than 1, it is recorded as the second state and enters S14; if the scattering parameter amplitude is 1 and is located in the fourth quadrant of the polar coordinate diagram, it is recorded as the third state and enters S15;

[0072] S13: Tilt the probe according to a preset step angle until the scattering parameter enters the second state, record the angle θ, and record it as A1; Tilt the probe in the opposite direction according to the preset step angle until the scattering parameter enters the second state again, record the angle θ, and record it as A2, and enter S16;

[0073] S14: Determine the side where the contact point that is not in contact with the contact pad is located, tilt the probe along the direction of the side according to a preset step angle, until the scattering parameter enters the first state, record the angle θ, and record it as A1; continue to tilt the probe according to the preset step angle until the scattering parameter enters the second state again, record the angle θ, and record it as A2, and enter S16;

[0074] S15: Determine the number of contacts that are not in contact with the contact pad, if it is 0, return to S12; if it is 1, return to S14;

[0075] S16: Set the target angle to the average value between A1 and A2, and adjust the angle θ between the connection line of the three contacts of GSG and the plane where the electrode touch plate is located to the target angle to complete the leveling operation.

[0076] When performing the leveling probe operation process, first manually adjust the suction cup position so that the three contacts of the probe tip GSG are just above the short-circuit calibration piece. Then, adjust the probe holder and gradually move the probe downward along the Z-axis direction. The step distance can be set to 1um. Each time a step is completed, the reflection parameters are recorded at the same time. By observing the sharp changes in the parameters, it is detected whether the three contacts of the probe tip touch the ground. After confirming that the probe is in contact with the short-circuit calibration piece, continue to adjust the probe to move downward along the Z-axis direction for about a certain distance, such as 5um, so that the probe tip is in good contact with the short-circuit calibration piece. Confirm the contact between the probe and the calibration piece by checking the scattering parameters.

[0077] When all three GSG contacts of the probe are in contact with the calibration piece, adjust the probe to a fixed distance in the Z-axis direction, such as 5um, and set it as the initial angle. Adjust the probe base so that the probe tilts along a certain step length. When the number of contacts at the probe tip changes from three to two, record the angle of the probe tilt, which is recorded as A1. Next, adjust the probe base so that the probe tilt angle returns to the initial angle and tilts in the opposite direction at a certain step length. When the number of contacts at the probe tip changes from three to two, record the angle of the probe tilt, which is recorded as A2.

[0078] When only two contacts of the probe are in contact with the calibration piece, the microscope is used to determine which side of the probe tip is not in contact, and the probe base is adjusted to make the probe tip tilt at a certain step length toward the side of the probe that is not in contact with the contact point. When the number of detected contact probe tips changes from two to three, the angle of the probe tilt at this point is recorded and recorded as A1. Next, the probe base is adjusted to make the probe continue to tilt in the same direction until the number of detected contact probe tips changes from three to two again, and the angle of the probe tilt at this point is recorded and recorded as A2.

[0079] After determining the angles of A1 and A2, adjust the probe holder so that the probe is adjusted a fixed distance in the Z-axis direction to release the probe and keep the probe tip away from the calibration surface to avoid damage to the probe tip when adjusting the probe angle later. Then, adjust the probe holder to set the probe tilt angle to the average value between A1 and A2 (A1+A2) / 2. After the adjustment is completed, the plane where the probe GSG is located is parallel to the surface of the calibration chip.

[0080] In one embodiment, the alignment operation of the initial position in S11 is performed according to the change of the real value of the scattering parameter.

[0081] In one embodiment, the control coordinate system is: the Z axis is perpendicular to the electrode contact plate direction, the XOY plane is parallel to the plane where the electrode contact plate is located, the X axis is the arrangement direction of the three contact pads, and the Y axis is the extension direction of the three contact pads on the wafer electrode contact plate; the alignment operation of the three-dimensional position of the probe is performed according to the change of the real part value of the scattering parameter, including:

[0082] Adjust the probe to an initial height, where the initial height is a fixed vertical distance between the probe and the wafer electrode contact plate;

[0083] The probe is controlled to move stepwise along the Y axis at the initial height according to the preset step distance. After each step is completed, the probe is controlled to move downward along the Z axis for a fixed distance value so that the contact point contacts the wafer electrode contact plate, and the scattering parameters are recorded until a steep increase signal appears in the real part value of the scattering parameter;

[0084] The probe is controlled to move stepwise along the X-axis at the initial height according to the preset step distance. After each step, the probe is controlled to move downward along the Z-axis for a fixed distance so that the contact point contacts the wafer electrode contact plate and the scattering parameters are recorded until a steep increase signal appears in the real part of the scattering parameter.

[0085] In this embodiment, the order of X-axis and Y-axis regulation is not particular. As an example, based on the leveling of the probe, this embodiment is described with the precise adjustment order of the coordinate axis direction being Z direction, Y direction, and X direction.

[0086] S21: First, determine the parameters of the probe tip in the Z direction. The control process can be achieved through the operator's experience and high-power microscope observation to ensure that the three contacts of the probe tip GSG are approximately aligned directly above the three contact pads of the electrode touch plate, but the probe does not touch the electrode touch plate. The operator then finely controls the probe position through the method of this embodiment. As shown in Figure 5(a), the probe tip is controlled in the Z-axis direction to slowly descend. The step distance is temporarily set to 1um. Each time a step is completed, the scattering parameters are recorded. By observing the parameter changes to determine that the probe has contacted the electrode touch plate, the position parameters of the probe in the Z-axis direction are confirmed.

[0087] S22: Adjust the probe to a fixed distance of 5um in the Z-axis direction to release the probe, so that the tip of the probe is away from the electrode contact pad. Adjust the probe seat to move the probe in the opposite direction of the Y-axis by about 1.5 times the distance of wp (set wp as the side length of the square contact of the calibration electrode), ensuring that it is away from the top of the electrode contact pad. Continue to adjust the probe seat, and gradually move the probe in the positive direction of the Y-axis. The step distance is temporarily set to 1um. After each step is completed, move the probe downward 5um in the Z-axis direction at one time, that is, press the probe so that the tip of the probe contacts the chip where the electrode contact pad is located, record the scattering parameters, and lift the probe to continue stepping. Repeat the above steps several times. When the scattering parameters are observed to change suddenly, it indicates that the tip of the probe has contacted the left edge of the three electrode contact points, and the position parameters of the probe in the Y-axis direction are confirmed.

[0088] S23: After detecting the left edge of the electrode contact pad on the Y axis, adjust the probe upward by 5um in the Z axis direction to release the probe and keep the probe tip away from the electrode contact pad. Then adjust the probe holder to move about 1.5 times the wp distance in the opposite direction of the X axis at one time, so that the probe tip leaves the top of the electrode contact pad in the X axis direction. Then, adjust the probe holder to gradually move the probe in the positive direction of the X axis, and set the step distance to 1um. After each step is completed, move the probe downward by 5um in the Z axis direction at one time, that is, press the probe so that the probe tip contacts the chip where the electrode contact pad is located, and record the scattering parameters. Lift the probe and continue stepping. Similar to the adjustment principle of the probe in the Y axis direction, repeat the above steps several times to confirm the position parameters in the X axis direction.

[0089] S24: The three GSG contact points at the tip of the probe are at the edge of the electrode contact pad in the Y-axis direction and at the edge of the electrode contact pad in the X-axis direction, that is, at the right-angle vertex of the XOY plane. After determining the coordinates of this point, since the size of the electrode contact pad is known, the probe is moved 0.5wp in the X-axis direction and the Y-axis direction toward the center of the electrode contact pad, which is the ideal target position for probe control.

[0090] like Figure 6 As shown, based on the above method, the repeatability of the probe coordinates and the pressing force can be achieved. Based on this electrode touch pad, all components on the wafer where the electrode touch pad is located can be repeatedly measured and analyzed with high precision.

[0091] In one embodiment, a vector network analyzer is used to obtain the scattering parameters of the three GSG contacts relative to the three contact pads in real time; after the calibration control module ensures the accuracy of the probe position and inclination, the vector network analyzer is calibrated with high precision. Therefore, the calibration steps of the vector network analyzer are also included:

[0092] Use calibration equipment to measure the actual S parameters of the DUT;

[0093] Calculate the S parameters of the equivalent model of the DUT in the vector network analyzer;

[0094] The residuals between the measured S parameters and the equivalent model S parameters are minimized using a nonlinear least squares algorithm.

[0095] When this embodiment is specifically implemented, the complex dielectric constant of the reference material is calculated by a computer and MATLAB software. In the measurement phase, we use a calibration device to measure the S parameters of the through-piece, short-circuit piece, open-circuit piece and transmission line, and these measurement data will be transmitted to the computer for further data processing. The data processing step includes inputting the basic information of the calibration device, reading the S parameter file of the vector network analyzer, and calculating the S parameters of the equivalent model. Finally, through the nonlinear least squares algorithm, we minimize the residual between the measured S parameters and the S parameters of the equivalent model, thereby extracting the error term of the vector network analyzer and completing the entire calibration process. Through this precise calibration method, we can ensure that the vector network analyzer performs high-precision measurements in a wide frequency range of 100MHz to 100GHz, providing a reliable basis for the precise analysis and measurement of high-frequency devices and systems.

[0096] The second aspect of the embodiment of the present invention further provides a radio frequency probe fully automatic control system according to the first aspect of the embodiment, comprising: a probe, a vector network analyzer, a control module, a probe GSG rotation angle fine-tuning system, a probe three-dimensional position control system and a wafer chuck; wherein,

[0097] The vector network analyzer is connected to the probe, which is used to obtain the scattering parameters of the three GSG contacts relative to the three contact pads in real time during the process of the probe moving and aligning relative to the wafer electrode contact plate;

[0098] The control module is connected to the vector network analyzer and is used to generate a leveling operation instruction of the probe according to the position of the polar coordinate diagram of the scattering parameter, including: generating a leveling operation instruction for adjusting the angle θ between the connection line of the three contacts of GSG and the plane where the electrode touch plate is located according to the position of the polar coordinate diagram of the scattering parameter, so that the connection line of the three contacts of GSG is parallel to the plane where the electrode touch plate is located; and generating an alignment operation instruction for the three-dimensional position of the probe according to the change of the real value of the scattering parameter, including: generating an alignment operation instruction for adjusting the position of the three contacts of GSG relative to the XYZ axes of the three contact pads according to the change of the real value of the scattering parameter, so that the three contacts of GSG are respectively in contact with the three contact pads;

[0099] The probe GSG rotation angle fine adjustment system is used to receive and execute leveling operation instructions;

[0100] The probe three-dimensional position control system is used to receive and execute alignment operation instructions;

[0101] The wafer chuck is used to fix the wafer electrode contact plate.

[0102] In one embodiment, a microscope is also included; the microscope is used to display the observation position of the probe relative to the wafer electrode contact plate; in the step of performing the leveling operation of the probe according to the amplitude change of the scattering parameter, the probe is adjusted to the initial position in combination with the observation position, the initial position is that the three contacts of GSG are located in the positive direction of the Z axis of the electrode contact plate, and are located in the corresponding position range relative to the three contact pads in the XOY plane; the angle θ is adjusted based on the initial position.

[0103] In one embodiment, a microscope is also included; the microscope is used to display the observation position of the probe relative to the wafer electrode contact plate; in the alignment operation step of the three-dimensional position of the probe is performed according to the change of the real value of the scattering parameter, the probe is adjusted to an initial height in combination with the observation position, and the initial height is a fixed distance value for the vertical distance between the probe and the wafer electrode contact plate; based on the initial height, the XYZ axis positions of the three contacts of the GSG relative to the three contact pads are regulated.

[0104] In one embodiment, Figure 7 As shown, a schematic diagram of the chip test probe station based on the probe automatic positioning system that can be used for time domain signal analysis of narrow pulse chips is shown, which includes design components for connecting GSG probes and nanopositioners. The probe station system is used to set up the probe XYZθ positioning device 4, the wafer chuck 5 and the microscope. Among them, the probe XYZθ positioning device 4 includes a probe GSG rotation angle fine-tuning system and a probe three-dimensional position control system, and the probe station system can use an air-floating probe station. A high-power microscope is set up on the probe station system through a highly stable microscope bridge. A 100MHz-100GHz vector network analyzer and a high-frequency 100um GSG probe are used, and a 6-inch wafer chuck can be adjusted.

[0105] The air-floating probe station and high-stability microscope bridge provide a stable and precise observation and operation platform for the system. By using a vector network analyzer and a high-power microscope, the contact point between the probe and the wafer can be accurately observed and analyzed. As a key component for contacting the wafer, the high-frequency GSG probe is precisely controlled by the probe three-dimensional position control system and the probe GSG rotation angle fine-tuning system. In addition, the adjustable 6-inch wafer chuck provides a stable fixing and adjustment platform for the wafer, and the calibration control chip is used for system calibration to ensure the accuracy of the probe position and tilt angle.

[0106] In this embodiment, the radio frequency probe fully automatic control system is used to execute the radio frequency probe fully automatic control method provided in the first aspect of the embodiment after coaxial calibration and SOL calibration.

[0107] In one embodiment, the probe three-dimensional position control and GSG rotation angle precision fine-tuning system adopts SmarAct's stick-slip drive technology. Since the SmarAct stick-slip drive piezoelectric displacement stage is equipped with a specific driver, it can achieve an efficient combination of macro travel and nano resolution. The precise adjustment of the probe rotation angle adopts SmarAct's SR series modules, such as the precision ceramic SR-2013 module, whose angular resolution reaches 25μ°. The precise adjustment in the X, Y and Z axis directions is planned to adopt SmarAct's SLC series modules based on cross roller bearing linear sliders. Such as the SLC1730 piezoelectric control platform with a size of 30x 17x 8.5mm, a travel range of 21mm, and a normal load of 20N, and the SLC2430 piezoelectric control platform with a size of 30x 24x 10.5mm, a travel range of 16mm, and a normal force of 30N. The closed-loop resolution MCS2 of both reaches 1(S)nm and 4(L)nm. By integrating stick-slip drive technology and microcomputer control system, the system significantly reduces the need for manual intervention and microscope use, thereby improving the level of automation in the testing process.

[0108] The above is a detailed introduction to the fully automatic control method and system of the radio frequency probe based on scattering parameter changes provided by the present invention. In this embodiment, specific examples are used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0109] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined in the present embodiments may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown in the present embodiment, but will conform to the widest range consistent with the principles and novel features disclosed in the present embodiment.

Claims

1. A fully automatic control method for a radio frequency probe based on changes in scattering parameters, characterized in that: The three contacts of the probe GSG are used to contact the three contact pads of the wafer electrode contact plate at the same time to realize wafer testing; the steps include: In the process of moving and aligning the probe relative to the wafer electrode contact plate, scattering parameters of the three GSG contact points relative to the three contact pads are obtained in real time; Performing a leveling operation of the probe according to the position of the polar coordinate diagram of the scattering parameter includes: adjusting the angle θ between the line connecting the three contacts of the GSG and the plane where the electrode touch plate is located according to the position of the polar coordinate diagram of the scattering parameter, so that the line connecting the three contacts of the GSG is parallel to the plane where the electrode touch plate is located; The three-dimensional position alignment operation of the probe is performed according to the change of the real value of the scattering parameter, including: adjusting the XYZ axis positions of the three contacts of the GSG relative to the three contact pads according to the change of the real value of the scattering parameter, so that the three contacts of the GSG are in contact with the three contact pads respectively.

2. The method for fully automatic control of radio frequency probes based on scattering parameter changes according to claim 1 is characterized in that: The probe leveling operation is performed according to the amplitude change of the scattering parameter, including: real-time judgment on whether the amplitude of the scattering parameter is 1 and is located in the second quadrant of the polar coordinate diagram. If so, the line connecting the three contacts of GSG is parallel to the plane where the wafer electrode contact plate is located, and the leveling operation is ended.

3. The method for fully automatic control of radio frequency probes based on scattering parameter changes according to claim 1 is characterized in that: The three-dimensional position alignment operation of the probe is performed according to the change of the real part value of the scattering parameter, including: real-time judgment on whether a steep increase signal appears in the real part value of the scattering parameter, and the change amplitude of the steep increase signal is greater than a preset value. If so, the three contacts of the GSG are in contact with the three contact pads respectively, thereby ending the three-dimensional position alignment operation.

4. The method for fully automatic control of radio frequency probes based on scattering parameter changes according to claim 1 is characterized in that: The control coordinate system is: the Z axis is perpendicular to the electrode touch plate direction, and the XOY plane is parallel to the plane where the electrode touch plate is located; the leveling operation of the probe is performed according to the amplitude change of the scattering parameter, including: S11: adjusting the probe to an initial position, wherein the initial position is that the three contacts of the GSG are located in the positive direction of the Z axis of the electrode contact plate and are located in a corresponding position range relative to the three contact pads in the XOY plane; S12: Control the probe to move gradually downward along the Z axis according to the preset step distance, and record the scattering parameter amplitude in real time. If the scattering parameter amplitude is 1 and is located in the second quadrant of the polar coordinate diagram, it is recorded as the first state and enters S13; if the scattering parameter amplitude is less than 1, it is recorded as the second state and enters S14; if the scattering parameter amplitude is 1 and is located in the fourth quadrant of the polar coordinate diagram, it is recorded as the third state and enters S15; S13: Tilt the probe according to a preset step angle until the scattering parameter enters the second state, record the angle θ, and record it as A1; Tilt the probe in the opposite direction according to the preset step angle until the scattering parameter enters the second state again, record the angle θ, and record it as A2, and enter S16; S14: Determine the side where the contact point that is not in contact with the contact pad is located, tilt the probe along the direction of the side according to a preset step angle, until the scattering parameter enters the first state, record the angle θ, and record it as A1; continue to tilt the probe according to the preset step angle until the scattering parameter enters the second state again, record the angle θ, and record it as A2, and enter S16; S15: Determine the number of contact points that are not in contact with the contact pad, if it is 0, return to S12; if it is 1, return to S14; S16: Setting the target angle to the average value between A1 and A2, and adjusting the angle θ between the connection line of the three contacts of GSG and the plane where the electrode contact plate is located to the target angle, thereby completing the leveling operation.

5. The method for fully automatic control of radio frequency probes based on scattering parameter changes according to claim 4 is characterized in that: The alignment operation of the initial position in S11 is performed according to the change of the real part value of the scattering parameter.

6. The method for fully automatic control of radio frequency probes based on scattering parameter changes according to claim 1 is characterized in that: The control coordinate system is: the Z axis is perpendicular to the electrode contact plate direction, the XOY plane is parallel to the plane where the electrode contact plate is located, the X axis is the arrangement direction of the three contact pads, and the Y axis is the extension direction of the three contact pads on the wafer electrode contact plate; the three-dimensional position alignment operation of the probe is performed according to the change of the real part value of the scattering parameter, including: Adjusting the probe to an initial height, wherein the initial height is a fixed distance between the probe and the wafer electrode contact plate; Control the probe to move stepwise along the Y axis at the initial height according to a preset step distance, and control the probe to move downward along the Z axis by the fixed distance value after each step is completed, so that the contact point contacts the wafer electrode contact plate, and record the scattering parameters until the real part value of the scattering parameter shows the steep increase signal; The probe is controlled to move stepwise along the X-axis at the initial height according to a preset step distance. After each step is completed, the probe is controlled to move downward along the Z-axis by the fixed distance value so that the contact point contacts the wafer electrode contact plate, and the scattering parameters are recorded until the real part value of the scattering parameter shows the steep increase signal.

7. The method for fully automatic control of radio frequency probes based on scattering parameter changes according to claim 1, characterized in that: Using a vector network analyzer to obtain scattering parameters of the three GSG contacts relative to the three contact pads in real time; also includes the calibration step of the vector network analyzer: Use calibration equipment to measure the actual S parameters of the DUT; Calculating S parameters of an equivalent model of a device under test in the vector network analyzer; The residuals between the measured S parameters and the equivalent model S parameters are minimized using a nonlinear least squares algorithm.

8. A radio frequency probe fully automatic control system according to any one of claims 1 to 7, characterized in that: include: Probe, vector network analyzer, control module, probe GSG rotation angle fine-tuning system, probe three-dimensional position control system and wafer chuck; among them, The vector network analyzer is connected to the probe and is used to obtain scattering parameters of the three GSG contacts relative to the three contact pads in real time during the process of the probe moving and aligning relative to the wafer electrode contact plate; The control module is connected to the vector network analyzer, and is used to generate a leveling operation instruction of the probe according to the position of the polar coordinate diagram of the scattering parameters, including: generating a leveling operation instruction for adjusting the angle θ between the connection line of the three contacts of GSG and the plane where the electrode touch pad is located according to the position of the polar coordinate diagram of the scattering parameters, so that the connection line of the three contacts of GSG is parallel to the plane where the electrode touch pad is located; and generating an alignment operation instruction for the three-dimensional position of the probe according to the change of the real value of the scattering parameters, including: generating an alignment operation instruction for adjusting the position of the three contacts of GSG relative to the XYZ axes of the three contact pads according to the change of the real value of the scattering parameters, so that the three contacts of GSG are respectively in contact with the three contact pads; The probe GSG rotation angle fine-tuning system is used to receive and execute the leveling operation instruction; The probe three-dimensional position control system is used to receive and execute the alignment operation instruction; The wafer chuck is used to fix the wafer electrode contact plate.

9. The radio frequency probe fully automatic control system according to claim 8, characterized in that: It also includes a microscope; the microscope is used to display the observation position of the probe relative to the wafer electrode contact plate; in the step of performing the leveling operation of the probe according to the amplitude change of the scattering parameter, the probe is adjusted to an initial position in combination with the observation position, and the initial position is that the three contacts of the GSG are located in the positive direction of the Z axis of the electrode contact plate and in the corresponding position range relative to the three contact pads in the XOY plane; the angle θ is regulated based on the initial position.

10. The radio frequency probe fully automatic control system according to claim 8, characterized in that: It also includes a microscope; the microscope is used to display the observation position of the probe relative to the wafer electrode touch plate; in the step of performing the three-dimensional position alignment operation of the probe according to the change of the real value of the scattering parameter, the probe is adjusted to an initial height in combination with the observation position, and the initial height is a fixed distance value for the vertical distance between the probe and the wafer electrode touch plate; based on the initial height, the positions of the three contacts of the GSG relative to the XYZ axes of the three contact pads are regulated.

Images