Chip for radio frequency probe regulation and control, preparation method and radio frequency probe regulation and control method

Abstract

The invention provides a radio frequency probe regulation and control chip, a preparation method and a radio frequency probe regulation and control method, the radio frequency probe regulation and control chip comprises a wafer substrate and a GSG type coplanar waveguide CPW structure formed on the wafer substrate, the GSG type coplanar waveguide CPW structure comprises a CPW signal line and CPW ground wires located on the two sides of the CPW signal line, the CPW signal line and the CPW ground wires are arranged in parallel, and the GSG type coplanar waveguide CPW structure is formed on the wafer substrate. The two CPW ground wires are electrically communicated with the CPW signal wire and then are used for being in contact with three contacts of the radio frequency probe GSG to realize position calibration of the radio frequency probe GSG; according to the scattering parameters of the three contacts of the GSG relative to the CPW signal line and the two CPW ground lines, the contact state of the three contacts of the GSG and the radio frequency probe regulation and control chip is judged, and the included angle theta between the connecting line of the three contacts of the GSG and the plane where the radio frequency probe regulation and control chip is located is regulated and controlled. According to the invention, different contact states, including complete open circuit, complete short circuit, partial contact and the like, of the probe can be accurately identified, so that the inclination angle and the contact position of the probe can be automatically regulated and controlled.

Description

Technical Field

[0001] This invention belongs to the field of microwave radio frequency testing and semiconductor micro-nano fabrication technology, and relates to high-frequency probe control technology and supporting thin-film circuit precision fabrication process. Specifically, it relates to a chip for radio frequency probe control, a fabrication method, and a radio frequency probe control method. Background Technology

[0002] Precise wafer testing technology, primarily based on probe stations, enables parameter measurement and precise calibration procedures, serving as a crucial step in the integrated circuit (IC) design and debugging process. In the semiconductor industry and related research fields, wafer test probe stations are currently mature tools for testing circuits and devices on wafers, with manual probe stations being the most prevalent.

[0003] Existing technologies have the following main problems in probe positioning and calibration:

[0004] First, mechanical adjustment methods rely on manual operation, which limits accuracy and is susceptible to human error, making it difficult to achieve high repeatability and automated adjustment.

[0005] Secondly, although optical detection methods can provide some positional information, they are difficult to accurately identify the electrical contact state between the probe and the chip surface. Especially in high-frequency testing, optical methods cannot effectively determine whether the probe has reached the optimal contact state.

[0006] Furthermore, existing feedback methods based on impedance measurement can usually only distinguish between open and short circuit states, and cannot accurately identify impedance changes caused by partial or different contact conditions of the probe, thus affecting measurement accuracy.

[0007] Furthermore, in high-frequency testing, the uncertainty of probe-chip contact may introduce additional parasitic effects, leading to test data deviations and affecting the stability and consistency of measurements.

[0008] Therefore, how to provide a chip for radio frequency probe control, a fabrication method, and a radio frequency probe control method to achieve high-precision, automated, and stable probe positioning in a high-frequency testing environment is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] In view of this, the present invention proposes a chip for radio frequency probe control, a fabrication method, and a radio frequency probe control method. By designing a coplanar waveguide calibration component, the present invention can accurately identify different contact states of the probe, including completely open circuit, completely short circuit, and partial contact, thereby realizing automatic control of the probe tilt angle and contact position.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] This invention discloses a chip for radio frequency probe modulation, comprising:

[0012] Wafer substrate;

[0013] The GSG-type coplanar waveguide (CPW) structure formed on the wafer substrate includes:

[0014] CPW signal line;

[0015] The CPW ground wires are located on both sides of the CPW signal line. The CPW signal line and the CPW ground wires are arranged in parallel. After the two CPW ground wires are electrically connected to the CPW signal line, they are used to contact the three contacts of the RF probe GSG to realize the position calibration of the RF probe GSG.

[0016] Preferably, a thin-film resistor is connected in parallel between each of the two CPW ground lines and the CPW signal line. The resistance value of the thin-film resistor is determined according to the characteristic impedance of the GSG type coplanar waveguide CPW structure. The characteristic impedance is determined according to the width of the CPW signal line and the distance between the CPW signal line and the CPW ground line.

[0017] Preferably, a thin-film resistor with the same resistance value is connected in parallel between each of the two CPW ground lines and the CPW signal line.

[0018] Preferably, the parallel resistance of the two thin-film resistors is the same as the resistive portion of the characteristic impedance.

[0019] Preferably, a thin-film resistor with a different resistance value is connected in parallel between each of the two CPW ground lines and the CPW signal line.

[0020] Preferably, one of the thin-film resistors has a resistance value greater than the resistance portion of the characteristic impedance, and the other thin-film resistor has a resistance value less than the resistance portion of the characteristic impedance.

[0021] The present invention also provides a method for fabricating an RF probe control chip according to the aforementioned RF probe control chip, comprising the following steps:

[0022] Prepare the wafer substrate;

[0023] A photomask used to lithographically form a thin-film resistive layer pattern on a wafer substrate;

[0024] A thin film resistive layer is magnetron sputtered on the surface of a wafer substrate with a photomask first, and then the photomask first and the thin film resistive layer on its surface are removed.

[0025] A metal layer is magnetron sputtered onto the surface of a wafer substrate with a thin film resistive layer.

[0026] A second mask is used to photolithographically form the pattern of the second metal layer on the surface of the first metal layer.

[0027] Electroplating of metal layer two on the surface of metal layer one where mask two is not formed, and removal of mask two;

[0028] The exposed metal layer is etched to form the radio frequency probe GSG control chip.

[0029] This invention also provides a method for adjusting an RF probe, wherein three contacts of the RF probe GSG are simultaneously connected to one CPW signal line and two CPW ground lines of the RF probe adjustment chip to achieve RF probe GSG position calibration; the method includes the following steps:

[0030] S1: During the process of moving and aligning the radio frequency probe GSG relative to the radio frequency probe control chip, the scattering parameters of the three contacts of the GSG relative to the one CPW signal line and the two CPW ground lines are acquired in real time.

[0031] S2: Perform the leveling operation of the RF probe GSG according to the polar coordinate diagram position of the scattering parameters, including: real-time determination of the number of amplitude points of the scattering parameters appearing in the polar coordinate diagram, and determining whether the amplitude points of the corresponding scattering parameters are located in the specified area of ​​the horizontal axis of the polar coordinate diagram based on the number. If yes, the three contacts of the GSG are simultaneously contacted with one CPW signal line and two CPW ground lines of the RF probe GSG control chip to complete the control; if not, proceed to S3.

[0032] S3: Adjust the angle θ between the line connecting the three contacts of GSG and the plane where the RF probe control chip is located, and repeat S2.

[0033] Preferably, in the RF probe control chip, a thin-film resistor with the same resistance value is connected in parallel between each of the two CPW ground lines and the CPW signal line; S2 includes:

[0034] Based on the measured normalized impedance corresponding to the amplitude point in the polar coordinate diagram, determine whether it meets the reference normalized impedance that allows the three contacts of the GSG to simultaneously contact one CPW signal line and two CPW ground lines of the RF probe control chip. If so, a matched load is formed, and the control is completed; otherwise, adjust the angle θ between the line connecting the three contacts of the GSG and the plane where the RF probe control chip is located.

[0035] Preferably, in the RF probe control chip, a thin-film resistor with a different resistance value is connected in parallel between each of the two CPW ground lines and the CPW signal line; S2 includes:

[0036] Based on the measured normalized impedance corresponding to the amplitude point in the polar coordinate diagram, determine whether it meets the reference normalized impedance that allows the three contacts of the GSG to simultaneously contact one CPW signal line and two CPW ground lines of the RF probe control chip. If so, a matched load is formed, and control is completed. If not, determine the direction of the angle θ between the line connecting the three contacts of the control GSG and the plane where the RF probe control chip is located, based on the magnitude of the measured normalized impedance, and execute the control.

[0037] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention include:

[0038] This invention solves the problem of accurate probe-to-chip contact state detection and tilt angle adjustment by designing short-circuit elements, symmetrical load elements, and asymmetrical load elements, all of which are designed on the same wafer.

[0039] The short-circuit element is used to distinguish between open-circuit and short-circuit states, providing a basic reference for probe contact status detection; the symmetrical load element makes the distribution position of the reflection parameter S11 on the impedance Smith diagram significantly different through parallel resistors, accurately distinguishing the probe contact status; the asymmetrical load element utilizes the characteristics of resistors with different resistance values ​​to directly determine the probe contact status and deflection angle setting, reducing the risk of misjudgment.

[0040] In terms of fabrication process, high-precision magnetron sputtering is used to achieve resistance control of ±0.3% between the gas and metal layers (GS), and photolithography is used to achieve fine pattern processing of 5μm. This ensures the high consistency of the TaN film resistance, thus providing a reliable hardware foundation for high-precision detection and adjustment of the probe-chip contact state, and improving the accuracy and reliability of the overall detection and adjustment.

[0041] This invention achieves precise judgment and automated adjustment of probe contact state through innovative coplanar waveguide design and precision thin film processing technology, effectively improving the accuracy and automation of probe positioning, and ensuring high repeatability and reliability of testing. This is of great significance for improving chip yield and reducing manufacturing costs. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0043] Figure 1 This is a structural diagram of a short-circuit chip for radio frequency probe control provided in an embodiment of the present invention;

[0044] Figure 2 This is a structural diagram of a symmetrical load chip for radio frequency probe modulation provided in an embodiment of the present invention;

[0045] Figure 3 This is a structural diagram of an asymmetric load chip for radio frequency probe modulation provided in an embodiment of the present invention;

[0046] Figure 4 This is a structural diagram of an open-circuit chip for radio frequency probe modulation provided in an embodiment of the present invention;

[0047] Figure 5 A flowchart illustrating the fabrication steps of a symmetrical load chip for radio frequency probe modulation provided in an embodiment of the present invention;

[0048] Figure 6 This is a schematic diagram illustrating different contact states between the probe and the contact point provided in an embodiment of the present invention;

[0049] Figure 7 A typical polar coordinate diagram showing the variation of the real part of the scattering parameter S11 during the probe approaching the chip surface, provided in an embodiment of the present invention.

[0050] Figure 8 Typical polar coordinate diagrams of the S11 parameter positions under different contact conditions for symmetrical load components provided in embodiments of the present invention;

[0051] Figure 9 Typical polar coordinate diagrams of the S11 parameter position points under different contact conditions for the asymmetric load component provided in the embodiments of the present invention. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention, ensuring stable and reliable electrical contact between the probe and the device under test, and improving test repeatability and data accuracy.

[0053] This invention is primarily applied to high-frequency testing (DC-67GHz) of semiconductor devices, integrated circuits, and microwave components. It is particularly suitable for probe contact status detection and optimization in high-frequency testing environments.

[0054] like Figure 1 As shown, a first aspect of the present invention provides a chip for radio frequency probe modulation, comprising:

[0055] Wafer substrate;

[0056] The GSG-type coplanar waveguide (CPW) structure formed on a wafer substrate includes:

[0057] CPW signal line;

[0058] The CPW ground wires are located on both sides of the CPW signal line. The CPW signal line and the CPW ground wires are arranged in parallel. After the two CPW ground wires are electrically connected to the CPW signal line, they are used to contact the three contacts of the RF probe GSG to realize the position calibration of the RF probe GSG.

[0059] It should be noted that electrical connectivity includes connections via a metal layer forming the CPW signal line and CPW ground line, or connections via a thin-film resistor. This can be used to form various types of RF probe control chips, such as short-circuit calibration devices, symmetrical load calibration devices, and asymmetrical load calibration devices. All calibration devices maintain the same CPW cross-sectional dimensions to ensure measurement consistency.

[0060] In one embodiment, a metal covering area independent of the CPW structure region is added to the RF probe control chip for preliminary visual leveling of the probe tip. When the probe approaches the chip surface, the relative position of the probe tip and the metal covering area can be observed to preliminarily determine the probe's horizontal state. The metal layer is planned to be made of gold or copper and can be precision-machined using processes such as magnetron sputtering.

[0061] In one embodiment, such as Figure 1 The image shows a short-circuit device formed using a GSG-type coplanar waveguide (CPW) structure. By observing the contact between the three contacts of the RF probe GSG and the short-circuit device, it can be determined whether all three contacts (GSG) of the probe are in contact with the chip surface.

[0062] exist Figure 1 In the diagram, the width and length of the contact pads for the CPW ground line and the CPW signal line are both wp, the spacing between the CPW ground line contact pads and the CPW signal line contact pads is sp, the distance from the CPW ground line contact pad to the chip edge is gp, the total length of the CPW structure is l, the total width is 2gp+2sp, the width of the CPW signal line is w, the spacing between the CPW signal line and the CPW ground line is s, the direction of the three points of the probe GSG is set as the X direction, the direction of the probe pressing and leaving the electrode contact plate is the Z direction, and the direction perpendicular to XOZ is the Y direction.

[0063] It should be noted that, in order to meet the requirement of probe contact pad position confirmation, probe contact pads are provided on both the CPW signal line and the CPW ground line of the calibration component.

[0064] In one embodiment, a thin-film resistor is connected in parallel between each of the two CPW ground lines and the CPW signal line. The resistance value of the thin-film resistor is determined based on the characteristic impedance of the GSG type coplanar waveguide CPW structure. The characteristic impedance is determined based on the width of the CPW signal line and the spacing between the CPW signal line and the CPW ground line.

[0065] In this embodiment, the thin-film resistor is a TaN thin-film resistor.

[0066] In this embodiment, as Figure 2 As shown, this is a symmetrical load device formed using a GSG-type coplanar waveguide (CPW) structure. A thin-film resistor of the same resistance is connected in parallel between each of the two CPW ground lines and the CPW signal line.

[0067] In one embodiment, the parallel resistance of the two thin-film resistors is the same as the resistive portion of the characteristic impedance.

[0068] In this embodiment, the characteristic impedance of the RF probe control chip is 50Ω, and the equivalent dielectric constant range is 5.25-5.5. The signal line width (w) and the distance between the signal line and the ground line (s) of the CPW need to comprehensively consider the 50Ω impedance matching, the contact requirements of the 100μm probe spacing, and the feasibility of fabrication. The symmetrical load calibration component uses a 50Ω standard load, which is achieved by connecting two 100Ω tantalum nitride (TaN) thin film resistors in parallel between the CPW signal line and the CPW ground line. By connecting two 100Ω thin film resistors in parallel with the short-circuit component, a matched load is formed when the probes are in full contact. The contact state of the probes can be accurately determined by the change of the S11 parameter.

[0069] In one embodiment, a thin-film resistor with a different resistance value is connected in parallel between each of the two CPW ground lines and the CPW signal line.

[0070] In one embodiment, one thin-film resistor has a resistance value greater than the resistive portion of its characteristic impedance, and the other thin-film resistor has a resistance value less than the resistive portion of its characteristic impedance.

[0071] In this embodiment, an 80Ω thin-film resistor is connected in parallel between one CPW ground line and the CPW signal line of the coplanar waveguide CPW structure, while a 50Ω thin-film resistor is connected in parallel between the other CPW ground line and the CPW signal line. Based on the characteristics of the asymmetric load, the deflection direction of the probe can be directly determined, that is, whether the left or right end of the GSG probe that is not in contact with the calibration component is suspended.

[0072] In one embodiment, when there is no electrical connection between the two CPW ground lines and the CPW signal line, an open-circuit calibration element is formed, such as... Figure 4 As shown.

[0073] The second aspect of this invention also provides a method for fabricating a radio frequency probe control chip according to the first aspect of this invention, such as... Figure 5 The location shown illustrates the basic steps of the process. The specific process for preparing the load calibration component includes the following steps:

[0074] S1: Prepare the wafer substrate. Use alumina as the substrate with a thickness of 600μm. Perform standard cleaning on the substrate to ensure that there are no impurities on the surface.

[0075] S2: Mask 1 for photolithographically forming a thin-film resistive layer pattern on a wafer substrate; specifically, mask 1 uses AZ5214 photoresist with a thickness of 1.5μm and a minimum linewidth of 5μm. The process involves spin coating, pre-baking, exposure, development, and cleaning to form the desired pattern.

[0076] S3: A thin-film resistor layer is magnetron sputtered onto the surface of the wafer substrate with photomask one etched on it. Specifically, the surface can be bombarded with Ar first, and then a tantalum nitride thin-film resistor layer can be sputtered. Subsequently, the unexposed photomask one and the thin-film resistor layer on its surface are removed, specifically by wet stripping. It should be noted that for the formation of two thin-film resistors with different resistance values ​​in the asymmetric load positioning device, different photomask patterns can be designed, and the thin-film material can be sputtered only in specific areas by using the mask to achieve two thin-film resistors with different resistance values.

[0077] S4: Magnetron sputtering of metal layer one on the surface of a wafer substrate with a thin film resistive layer. Specifically, Ti and Au metal layers one were sputtered in this case, with a sputtering thickness of 100nm for each.

[0078] S5: A second mask is used to photolithographically form the pattern of the second metal layer on the surface of the first metal layer. Specifically, the second mask (mask2) uses AZ4620 photoresist with a thickness of 10μm and a minimum linewidth of 13μm. The mask undergoes spin coating, pre-baking, exposure, development, and cleaning to form the desired pattern for the second metal layer.

[0079] S6: Electroplat the second metal layer on the surface of the first metal layer before the second mask is formed. Specifically, you can apply adhesive (pretreatment) before electroplating, and then electroplat the second Au metal layer with a thickness of 3.5μm. After that, remove the unexposed second mask. Specifically, you can use a wet adhesive removal method.

[0080] S7: Etch the exposed metal layer 1. Specifically, Ti or Au etching technology can be used for wet etching to etch the excess areas of the metal layer 1 (Ti or Au). This completes the entire fabrication process of the load device, forming the RF probe GSG control chip.

[0081] It should be noted that magnetron sputtering is one of the physical vapor deposition (PVD) methods. The reason why PVD was chosen as the processing method for thin-film resistors in this embodiment is that the shapes of thin-film resistors are usually relatively simple (mostly rectangular), eliminating the need for complex CVD processes to achieve complex shapes. Meanwhile, although ALD can achieve high-quality thin films, its deposition rate is slow, its cost is high, and it is typically used for thinner films. However, the required thin-film resistor thickness for calibration sheets (on the order of 10 nm) is relatively large, making ALD unsuitable. Therefore, considering processing efficiency, cost, and thin-film performance, PVD is a more suitable method for processing calibration sheet thin-film resistors.

[0082] In one embodiment, a TaN thin-film resistor is used. The core of the load calibration device is the fabrication of the TaN thin-film resistor. The TaN thin film is deposited using magnetron sputtering, and its sheet resistance is determined by the following formula:

[0083]

[0084] Where ρ is the resistivity and t is the film thickness. To achieve a 100Ω resistance, the film thickness is on the order of 10nm. Since the skin depth of TaN at 67GHz is 6.69μm, which is much larger than the film thickness (more than 200 times), the skin effect can be ignored, and the resistance value remains stable over a wide frequency range.

[0085] Since the tantalum nitride film is very thin, the resistivity increases as the thickness decreases. Therefore, before fabrication, tantalum nitride needs to be sputtered first to confirm the appropriate sputtering thickness, thereby determining the sheet resistance. Based on the stable sheet resistance, the mask is modified and photolithography is performed.

[0086] A third aspect of this invention also provides a radio frequency probe (RF) probe control method, wherein three contacts of the RF probe GSG are simultaneously connected to one CPW signal line and two CPW ground lines of the RF probe control chip of the first aspect of this invention to achieve RF probe GSG position calibration; the method includes the following steps:

[0087] S1: During the process of moving and aligning the RF probe GSG relative to the RF probe control chip, the scattering parameters of the three contacts of the GSG relative to one CPW signal line and two CPW ground lines are acquired in real time.

[0088] S2: Perform the leveling operation of the RF probe GSG according to the position of the polar coordinate graph of the scattering parameters, including: real-time judgment of the number of amplitude points of the scattering parameters appearing in the polar coordinate graph, and judging whether the amplitude points of the corresponding scattering parameters are located in the specified area of ​​the horizontal axis of the polar coordinate graph based on the number. If yes, the three contacts of the GSG are simultaneously contacted with one CPW signal line and two CPW ground lines of the RF probe GSG control chip to complete the control; if not, proceed to S3.

[0089] S3: Adjust the angle θ between the line connecting the three contacts of GSG and the plane where the RF probe control chip is located, and repeat S2.

[0090] In one embodiment, for Figure 1 The short-circuit calibration device shown has no electrical loop between its tip ground point G and signal point S when the RF probe GSG is floating; it is in an open-circuit state. At this time, the reflection parameter S11 is located on the lower right side of the impedance Smith diagram, as shown below. Figure 7 The part shown by the red line in the middle, and |S11|=1. To distinguish the open circuit state, the most typical reference structure is the short circuit.

[0091] There are three typical situations when the three contacts of the GSG probe make contact with the chip, such as... Figure 6 As shown, when the angle θ between the straight line containing the three G, G, and S contacts of the probe and the chip contact surface is large, only one G contact point is in contact with the chip; when θ is small, one G and one S contact point may be in contact with the chip, while the other G contact point 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.

[0092] To distinguish between the three contact scenarios mentioned above, a short-circuit contact plate can be used to simulate a 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 for one G contact point contacting the chip is two capacitors in parallel; the equivalent circuit diagram for one G and one S contact point contacting the chip is one capacitor and one inductor in parallel; the equivalent circuit diagram for all three G and one S contacts contacting the chip is two inductors in parallel. Figure 3 The figure shows typical polar plots (x-axis is real, y-axis is imaginary) of the corresponding scattering parameters obtained from a vector network analyzer (VNA) under different contact conditions. The numbers in the figure represent the number of contact probe tips (G or S).

[0093] When all three contacts of the probe (GSG) are in good contact with the electrodes of the short-circuit contact plate, two parallel circuits are formed between each ground contact G and the signal contact S. Therefore, there should be an inductance between them, and the amplitude of the scattering parameter |S11| obtained accordingly is approximately 1. In the upper left region of the Smith chart, as shown... Figure 7 The part marked with a green line;

[0094] When only one of the three G contacts of the probe makes good contact with the short-circuit contact plate electrode, or when none of the three contacts make good contact with the short-circuit contact plate electrode, no loop is formed between each grounding contact G and the signal contact S. An equivalent capacitance should exist between the G contact and the S contact, and the corresponding obtained scattering parameter amplitude |S11| is approximately 1. This is located in the lower right region of the Smith chart, as shown below. Figure 7 The part marked with a red line in the middle;

[0095] When only one of the three GSG contacts of the probe, the S contact and the G contact, make good contact with the short-circuit contact plate electrode, a loop is formed between the G contact and the S contact, corresponding to an equivalent inductance. However, the other G contact does not form a loop with the S contact, corresponding to an equivalent capacitance. The inductance and capacitance, connected in parallel, resonate over a wide frequency range. Consequently, the amplitude of the obtained scattering parameter |S11| is mostly less than 1, falling within the inner region of the Smith chart. Figure 7 The area marked with a blue line.

[0096] Therefore, based on the characteristics of the S11 parameter, the actual contact position and degree of contact of the three contacts can be determined by analyzing the change law of the S11 parameter when the three GSG contacts of the probe tip come into contact with the contact plate. The main focus is on leveling the probe tilt angle so that when the leveled probe moves to the actual contact pad of the target wafer chip, it can still ensure calibration accuracy based on the accurate contact tilt angle.

[0097] As can be seen from the above adjustment process, during the adjustment of the GSG tip tilt angle, when all GSGs are in the air or only one G contacts the chip electrode contact plate or short-circuit positioning component, the equivalent circuit between the three points of the GSG is open. When all three points of the GSG are in contact with the short-circuit positioning component, the GSG is short-circuited. When one G and S are in contact with the short-circuit positioning component while the other G is suspended in the air, there is a short circuit between the two contacting GSGs, and an open circuit between the G in the air and the S in contact with the short-circuit component, forming a parallel equivalent circuit of inductance and capacitance. At this time, LC parallel resonance may exist, which can be used as the basis for judging that only two points of the probe are in contact with the positioning component. However, based on previous research experience, for the commonly used 100μm probe spacing coplanar waveguide short-circuit structure, the equivalent inductance value generated may be on the order of nH, while the equivalent capacitance value of the probe suspended in the air may be on the order of fF. Considering that the embodiments of this invention are mainly used in the DC-67GHz low-frequency band, the LC parallel resonance generated in this frequency band may not be obvious. Therefore, the following embodiments propose methods for regulating RF probes using symmetrical load calibrators and asymmetrical load calibrators.

[0098] In one embodiment, for Figure 2 The symmetrical load calibration device shown includes a thin-film resistor of the same resistance connected in parallel between each of the two CPW ground lines and the CPW signal line in the RF probe control chip; S2 includes:

[0099] Based on the measured normalized impedance corresponding to the amplitude point in the polar coordinate diagram, determine whether it meets the reference normalized impedance that allows the three contacts of the GSG to simultaneously contact one CPW signal line and two CPW ground lines of the RF probe control chip. If so, a matched load is formed, and the control is completed; otherwise, adjust the angle θ between the line connecting the three contacts of the GSG and the plane where the RF probe control chip is located.

[0100] In this embodiment, a symmetrical load calibration element with a characteristic impedance of 50Ω is used. This structure, based on the short-circuit calibration element, adds a 100Ω thin-film resistor in parallel between each of the two CPW ground lines and the CPW signal lines. When all three GSG contact points of the probe are in contact with the load positioning element, a matched load is formed, causing the reflection parameter S11 to fall into the central region of the impedance Smith chart, approaching the normalized impedance 1. Figure 8 The green dot in the diagram. When one G contact of the RF probe GSG is in contact with a CPW ground line of the RF probe control chip, one S contact is in contact with a CPW signal line of the RF probe control chip, and the other G contact is left floating, the GSG forms an equivalent circuit consisting of a 100Ω resistor and a small capacitor in parallel. The corresponding reflection parameter S11 is located near the normalized impedance 2 on the horizontal axis of the impedance Smith chart, as shown in the diagram. Figure 4 Red dot. When only one G-contact of the probe is in contact with one CPW ground wire of the RF probe control chip, its reflection parameter S11 remains on the right side of the impedance Smith chart, near the lower region of infinite impedance, as shown below. Figure 7 The red line section.

[0101] Since the three contact states are distributed in significantly different positions on the impedance Smith chart, this structure can more accurately distinguish the probe tilt state, including GSG full contact, GS two-point contact, G one-point contact or open circuit state, thereby optimizing the automatic adjustment process of the probe.

[0102] In one embodiment, for Figure 3 The asymmetric load calibration device shown includes a thin-film resistor with a different resistance connected in parallel between each of the two CPW ground lines and the CPW signal line in the RF probe control chip; S2 includes:

[0103] Based on the measured normalized impedance corresponding to the amplitude point in the polar coordinate graph, determine whether it meets the reference normalized impedance that allows the three contacts of the GSG to simultaneously contact one CPW signal line and two CPW ground lines of the RF probe control chip. If so, a matched load is formed, and control is completed. If not, determine the direction of the angle θ between the line connecting the three contacts of the control GSG and the plane where the RF probe control chip is located, based on the magnitude of the measured normalized impedance, and execute the control.

[0104] In this embodiment, an 80Ω thin-film resistor is connected in parallel between one CPW ground line and the CPW signal line of the coplanar waveguide CPW structure, while a 50Ω thin-film resistor is connected in parallel between the other CPW ground line and the CPW signal line. When all three GSG contacts of the probe are in contact with the asymmetric positioning element, a load circuit with an equivalent resistance of approximately 30Ω is formed. The corresponding reflection parameter S11 is located on the right side of the horizontal axis of the impedance Smith diagram, close to the normalized impedance of 0.6. Figure 8 Blue dot. When one G contact of the probe is in contact with a CPW ground line of the RF probe control chip, one S contact is in contact with a CPW signal line of the RF probe control chip, and the other G contact is floating, two equivalent circuits may occur:

[0105] First, the 80Ω resistor and small capacitor are connected in parallel. Their reflection parameter S11 falls to the right of the horizontal axis of the impedance Smith chart, close to the normalized impedance of 1.6. Figure 9 Red dot.

[0106] Secondly, the 50Ω resistor and small capacitor are connected in parallel, and their reflection parameter S11 is located in the central region of the Smith chart, close to the normalized impedance of 1. Figure 9 Green dot.

[0107] The advantage of this structure is that the contact status of the probe can be directly determined by the difference in normalized impedance. Furthermore, when only two contacts of the probe are in contact with the positioning element, the probe's deflection angle can be directly determined based on the characteristics of the asymmetrical load, eliminating the need for manual adjustment and reducing the risk of human error, thus preventing probe damage due to operational mistakes.

[0108] The present invention has provided a detailed description of a radio frequency probe control chip, its preparation method, and its radio frequency probe control method. Specific examples have been used in this embodiment to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

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

Claims

1. A chip for radio frequency probe control, characterized in that, include: Wafer substrate; The GSG-type coplanar waveguide (CPW) structure formed on the wafer substrate includes: CPW signal line; The CPW ground wires are located on both sides of the CPW signal line. The CPW signal line and the CPW ground wires are arranged in parallel. After the two CPW ground wires are electrically connected to the CPW signal line, they are used to contact the three contacts of the RF probe GSG to realize the position calibration of the RF probe GSG.

2. The RF probe control chip according to claim 1, characterized in that, A thin-film resistor is connected in parallel between each of the two CPW ground lines and the CPW signal line. The resistance value of the thin-film resistor is determined according to the characteristic impedance of the GSG type coplanar waveguide CPW structure. The characteristic impedance is determined according to the width of the CPW signal line and the distance between the CPW signal line and the CPW ground line.

3. The RF probe control chip according to claim 2, characterized in that, A thin-film resistor of the same resistance is connected in parallel between each of the two CPW ground lines and the CPW signal line.

4. The RF probe control chip according to claim 3, characterized in that, The parallel resistance of the two thin-film resistors is the same as the resistive portion of the characteristic impedance.

5. A radio frequency probe control chip according to claim 2, characterized in that, A thin-film resistor with a different resistance value is connected in parallel between each of the two CPW ground lines and the CPW signal line.

6. A radio frequency probe control chip according to claim 5, characterized in that, One of the thin-film resistors has a resistance value greater than the resistance portion of the characteristic impedance, and the other thin-film resistor has a resistance value less than the resistance portion of the characteristic impedance.

7. A method for fabricating a radio frequency probe control chip according to any one of claims 1-6, characterized in that, Includes the following steps: Prepare the wafer substrate; A photomask used to lithographically form a thin-film resistive layer pattern on a wafer substrate; A thin film resistive layer is magnetron sputtered on the surface of a wafer substrate with a photomask first, and then the photomask first and the thin film resistive layer on its surface are removed. A metal layer is magnetron sputtered onto the surface of a wafer substrate with a thin film resistive layer. A second mask is used to photolithographically form the pattern of the second metal layer on the surface of the first metal layer. Electroplating of metal layer two on the surface of metal layer one where mask two is not formed, and removal of mask two; The exposed metal layer is etched to form the radio frequency probe GSG control chip.

8. A method for controlling a radio frequency probe, characterized in that, The three contacts of the radio frequency probe GSG are used to simultaneously contact one CPW signal line and two CPW ground lines of the radio frequency probe control chip according to any one of claims 1-6 to realize the position calibration of the radio frequency probe GSG. Includes the following steps: S1: During the process of moving and aligning the radio frequency probe GSG relative to the radio frequency probe control chip, the scattering parameters of the three contacts of the GSG relative to the one CPW signal line and the two CPW ground lines are acquired in real time. S2: Perform the leveling operation of the RF probe GSG according to the polar coordinate diagram position of the scattering parameters, including: real-time determination of the number of amplitude points of the scattering parameters appearing in the polar coordinate diagram, and determining whether the amplitude points of the corresponding scattering parameters are located in the specified area of ​​the horizontal axis of the polar coordinate diagram based on the number. If yes, the three contacts of the RF probe GSG are simultaneously in contact with one CPW signal line and two CPW ground lines of the RF probe GSG control chip to complete the control; if not, proceed to S3. S3: Adjust the angle θ between the line connecting the three contacts of GSG and the plane where the RF probe control chip is located, and repeat S2.

9. The radio frequency probe modulation method according to claim 8, characterized in that, In the RF probe control chip, a thin-film resistor of the same resistance value is connected in parallel between each of the two CPW ground lines and the CPW signal line; S2 includes: Based on the measured normalized impedance corresponding to the amplitude point in the polar coordinate diagram, determine whether it meets the reference normalized impedance that allows the three contacts of the GSG to simultaneously contact one CPW signal line and two CPW ground lines of the RF probe control chip. If so, a matched load is formed, and the control is completed; otherwise, adjust the angle θ between the line connecting the three contacts of the GSG and the plane where the RF probe control chip is located.

10. The radio frequency probe modulation method according to claim 8, characterized in that, In the RF probe control chip, a thin-film resistor with a different resistance value is connected in parallel between each of the two CPW ground lines and the CPW signal line; S2 includes: Based on the measured normalized impedance corresponding to the amplitude point in the polar coordinate diagram, determine whether it meets the reference normalized impedance that allows the three contacts of the GSG to simultaneously contact one CPW signal line and two CPW ground lines of the RF probe control chip. If so, a matched load is formed, and control is completed. If not, determine the direction of the angle θ between the line connecting the three contacts of the control GSG and the plane where the RF probe control chip is located, based on the magnitude of the measured normalized impedance, and execute the control.

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