Radio frequency on-chip test system and method

Abstract

The invention discloses a radio frequency on-chip test system and a radio frequency on-chip test method. The radio frequency on-chip test system comprises a probe temperature adjusting module, an instantaneous pulse acquisition module, a dynamic compensation module, a thermal isolation module, radio frequency measurement equipment and a bearing platform. Wherein the probe temperature adjusting module is used for independently adjusting the temperature of a probe to a target value; the instantaneous pulse acquisition module is used for transmitting a radio frequency pulse signal and acquiring a radio frequency parameter when the probe is in contact with the normal temperature calibration sheet; the dynamic compensation module dynamically corrects the radio frequency parameters based on the real-time temperature of the probe; the thermal isolation module is used for reducing heat exchange between the probe and the external environment; the radio frequency measuring equipment is used for collecting and analyzing the radio frequency parameters; the bearing platform is used for bearing the normal temperature calibration sheet or the device to be tested. Through the synergistic effect of multiple modules, the problem of test errors caused by temperature fluctuation is effectively solved, and the precision and stability of radio frequency on-chip test are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of electronic testing technology, and in particular to a radio frequency on-wafer testing system and method. Background Art

[0002] RF on-wafer testing is a core method for evaluating high-frequency performance in semiconductor device R&D and production. Its measurement accuracy directly determines the reliability of chip functional verification and mass production yield. However, existing test systems have the following shortcomings: probe temperature is easily affected by heat exchange in the external environment and fluctuates, resulting in temperature drift errors in the RF parameters collected when in contact with a normal-temperature calibration plate. Furthermore, the probe temperature cannot be accurately adjusted independently, making it difficult to adapt to the temperature requirements of different test scenarios. This makes the calibration process unable to accurately reflect the probe's actual operating status, ultimately affecting the consistency and accuracy of the measurement results of the device under test. Summary of the Invention

[0003] The object of the present invention is to provide a radio frequency on-wafer testing system and method.

[0004] In a first aspect, an embodiment of the present invention provides a radio frequency on-wafer test system, comprising:

[0005] Probe temperature adjustment module, used to independently adjust the probe temperature to the target value;

[0006] The instantaneous pulse acquisition module is used to transmit a radio frequency pulse signal and acquire radio frequency parameters when the probe contacts the normal temperature calibration piece;

[0007] A dynamic compensation module, configured to dynamically correct the radio frequency parameters based on the real-time temperature of the probe;

[0008] Thermal isolation module, used to reduce heat exchange between the probe and the external environment;

[0009] Radio frequency measurement equipment, used to collect and analyze the radio frequency parameters;

[0010] The carrying platform is used to carry the normal temperature calibration piece or the device to be tested.

[0011] In one possible embodiment, the probe temperature adjustment module includes a thermoelectric cooler, a liquid cooling unit and a temperature sensor; the thermoelectric cooler and the liquid cooling unit are directly attached to the probe handle to achieve rapid temperature adjustment of the probe, with an adjustment rate of ≥15°C / s; the temperature sensor is embedded in the probe tip, and the temperature measurement accuracy is ±0.1°C.

[0012] In a possible implementation, the radio frequency pulse signal emitted by the instantaneous pulse acquisition module has a pulse width of ≤5 μs, and the radio frequency pulse signal is acquired within a thermal relaxation time window after the probe contacts the normal temperature calibration piece, and the thermal relaxation time is >5 ms.

[0013] In a possible implementation, the dynamic compensation module has a built-in probe temperature-electrical characteristic mapping database, where the electrical characteristics include impedance, insertion loss, and phase. The dynamic compensation module performs real-time correction on the RF parameter measurement values ​​through interpolation calculation.

[0014] In a possible embodiment, the thermal isolation module is an air curtain insulation device, which forms a directional airflow barrier around the probe through an annular compressed air nozzle, and the flow rate of the directional airflow barrier is 6-12 m / s.

[0015] In a second aspect, an embodiment of the present invention provides a radio frequency on-wafer testing method, which is applied to the radio frequency on-wafer testing system described in the first aspect. The method includes:

[0016] Keep the calibration piece at room temperature and adjust the probe temperature to the target temperature through the probe temperature adjustment module;

[0017] The control probe is brought into contact with the normal temperature calibration piece, and a radio frequency pulse signal is emitted through the instantaneous pulse acquisition module to acquire radio frequency parameters;

[0018] Dynamically correcting the radio frequency parameters based on the real-time temperature of the probe by a dynamic compensation module;

[0019] Switch to the device under test, and repeat the steps of keeping the calibration plate at room temperature, adjusting the probe temperature to the target temperature through the probe temperature adjustment module, and dynamically correcting the RF parameters based on the real-time temperature of the probe through the dynamic compensation module to obtain the temperature-compensated RF parameters of the device under test.

[0020] In a possible implementation, the target temperature is adjusted within a range of -55°C to 200°C, and the probe temperature adjustment module takes less than or equal to 1 second to adjust the probe temperature to the target temperature.

[0021] In a possible implementation, the pulse width of the radio frequency pulse signal is ≤5 μs, and acquisition is completed within a thermal relaxation time window after the probe contacts the normal temperature calibration piece, and the thermal relaxation time is >5 ms.

[0022] In a possible implementation, the dynamic correction is performed by interpolating and correcting the radio frequency parameters by calling a pre-stored probe temperature-impedance relationship curve;

[0023] The interpolation correction includes phase compensation. The phase compensation formula is ΔΦ=α(T)·ΔT, where ΔΦ is the phase correction amount, α(T) is the temperature correlation coefficient, and ΔT is the difference between the real-time temperature of the probe and the reference temperature.

[0024] In one possible implementation, the method further includes:

[0025] When adjusting the probe temperature, a directional airflow barrier is opened through the thermal isolation module to reduce heat exchange between the probe and the external environment. The flow rate of the directional airflow barrier is 6-12 m / s.

[0026] Compared with the prior art, the beneficial effects provided by the present invention include: using a radio frequency on-wafer test system and method disclosed in the present invention, the radio frequency on-wafer test system includes a probe temperature adjustment module, an instantaneous pulse acquisition module, a dynamic compensation module, a thermal isolation module, a radio frequency measurement device and a carrying platform. Among them, the probe temperature adjustment module is used to independently adjust the probe temperature to the target value; the instantaneous pulse acquisition module is used to transmit a radio frequency pulse signal and collect radio frequency parameters when the probe contacts the normal temperature calibration piece; the dynamic compensation module dynamically corrects the radio frequency parameters based on the real-time temperature of the probe; the thermal isolation module is used to reduce the heat exchange between the probe and the external environment; the radio frequency measurement device is used to collect and analyze the radio frequency parameters; the carrying platform is used to carry the normal temperature calibration piece or the device to be tested. Through the synergistic effect of multiple modules, the test error problem caused by temperature fluctuations is effectively solved, and the accuracy and stability of radio frequency on-wafer testing are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly describes the drawings required for use in the embodiments. It should be understood that the following drawings illustrate only certain embodiments of the present invention and should not be construed as limiting the scope of the present invention. Those skilled in the art can, without inventive effort, derive other relevant drawings from these drawings.

[0028] Figure 1 A schematic diagram of the framework of a radio frequency on-wafer test system provided by an embodiment of the present invention;

[0029] Figure 2 A schematic flow chart of the steps of a radio frequency on-wafer testing method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the embodiments of the present invention. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, not all of them. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

[0031] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0032] In order to solve the technical problems in the above background technology, Figure 1This is a schematic diagram of the framework of a radio frequency on-wafer test system provided in an embodiment of the present disclosure. The radio frequency on-wafer test system is introduced in detail below.

[0033] Probe temperature adjustment module, used to independently adjust the probe temperature to the target value;

[0034] The instantaneous pulse acquisition module is used to transmit a radio frequency pulse signal and acquire radio frequency parameters when the probe contacts the normal temperature calibration piece;

[0035] A dynamic compensation module, configured to dynamically correct the radio frequency parameters based on the real-time temperature of the probe;

[0036] Thermal isolation module, used to reduce heat exchange between the probe and the external environment;

[0037] Radio frequency measurement equipment, used to collect and analyze the radio frequency parameters;

[0038] The carrying platform is used to carry the normal temperature calibration piece or the device to be tested.

[0039] In the embodiment of the present invention, for example, in the specific implementation process of the RF on-wafer test system, the server acts as the core control unit to coordinate the collaborative operation of the probe temperature adjustment module, the transient pulse acquisition module, the dynamic compensation module, the thermal isolation module, the RF measurement equipment and the carrier platform to achieve accurate calibration and testing of RF S parameters in a wide temperature range (-55°C to 200°C). Figure 1 The system architecture shown (network analyzer, pulse generator, temperature control module, gas shield / temperature compensation unit (including thermal isolation module (gas shield) and dynamic compensation module (temperature compensation unit)), probe, calibration piece, and signal and control links of the probe station) is specifically implemented as follows:

[0040] During the system startup phase, the server first completes hardware topology mapping and resource pre-configuration: Figure 1Based on the hardware connection relationship, the server establishes the RF signal transmission model of "pulse generator → probe → calibration plate → network analyzer" and the temperature control feedback model of "temperature control module → probe handle, temperature sensor → probe tip" to ensure that the instructions accurately reach each hardware node; at the same time, it loads the probe temperature-electrical characteristic mapping database constructed by the "probe temperature-electrical characteristic calibration experiment" (covering the change law of electrical characteristics such as probe impedance, insertion loss, phase with temperature in the range of -55℃ to 200℃) to provide data support for subsequent dynamic compensation. For each functional module, the server sends initialization parameters in turn: sends an "initial flow rate 6m / s" command to the thermal isolation module (air curtain insulation device) to drive the annular compressed air nozzle to form a directional airflow barrier around the probe; configures the acquisition parameters such as "test frequency band 20GHz, sampling rate 100MS / s" to the RF measurement equipment (network analyzer); transmits the "normal temperature calibration piece (25℃ standard ISS calibration piece) coordinates (X: 50mm, Y: 30mm)" to the carrier platform (probe station), and the probe station robotic arm moves the calibration piece to the test station.

[0041] Entering the probe temperature control phase, taking the low-temperature -55°C test scenario as an example: the server sends a "target temperature -55°C" command to the probe temperature control module (integrated with a thermoelectric cooler (TEC), a liquid cooling unit, and a temperature sensor), triggering the TEC cooling mode and the liquid cooling unit's cyclic cooling program (both directly attached to the probe handle, achieving a cooling rate of ≥15°C / s). The temperature sensor at the probe tip (temperature measurement accuracy of ±0.1°C) transmits real-time temperature data at a frequency of 100Hz. The server dynamically adjusts the TEC power and liquid cooling flow rate based on the PID temperature control algorithm, bringing the probe temperature quickly close to the target value. When the temperature data stabilizes within the "-55±0.3°C" range for 10 consecutive sampling cycles (a total of 100ms), the server determines that the temperature control meets the standard, instructs the temperature control module to stop adjustment, and increases the air curtain flow rate of the thermal isolation module to 10m / s (to enhance low-temperature insulation and prevent ambient heat from reversely heating the probe). If the test is performed at a high temperature of 200°C, the server triggers the TEC heating mode and cooperates with the liquid cooling unit to maintain temperature stability. The air curtain opens synchronously to isolate the ambient heat radiation and ensure that the probe temperature fluctuation is ≤0.5°C.

[0042] The instantaneous pulse acquisition process needs to accurately avoid heat exchange interference: the server instructs the carrying platform to drive the probe to fall vertically (displacement accuracy ≤ 5μm). When the tip of the probe contacts the normal temperature calibration piece, the pressure sensor inside the probe sends a "contact signal" back to the server; the server immediately triggers the instantaneous pulse acquisition module (pulse generator) to output an ultra-narrow pulse width RF pulse with a pulse width of ≤ 5μs. This pulse must be transmitted and collected before the thermal relaxation time window after the probe contacts the calibration piece (because the thermal relaxation time is greater than 5ms, and the pulse width is only 5μs, the pulse window completely covers the initial stable section of the thermal relaxation heating curve, ensuring that the temperature fluctuation of the calibration piece is less than 0.1℃). The RF signal reflected / transmitted by the calibration piece is transmitted to the RF measurement equipment (network analyzer) through the probe. After analysis, the equipment will "the original measurement value of the S parameter (such as S 11 Reflection coefficient, S 21 Transmission coefficient)" is sent back to the server for temporary storage.

[0043] During dynamic compensation, the server uses a preloaded database of probe temperature-electrical characteristic mappings and combines them with the probe's real-time temperature to perform S-parameter corrections. For example, if the probe's real-time temperature is -55.1°C (using low-temperature testing as an example), the server extracts the probe's impedance offset, insertion loss change, and phase drift coefficient (e.g., phase drift coefficient α = -0.02° / °C) at that temperature. Substituting this into the phase compensation formula ΔΦ = α(T)·ΔT (where ΔT is the difference between the real-time temperature and a reference temperature of 25°C, i.e., -55.1 - 25 = -80.1°C), the server calculates the phase correction ΔΦ = +1.602°, narrowing the original phase error from +1.1° to within ±0.3°. For the insertion loss parameter, the server applies linear interpolation compensation based on the "temperature-insertion loss" fitted curve to return the measured value to the baseline level. During high-temperature testing at 200°C, if a 2% increase in probe resistance due to temperature rise is detected, the compensation unit automatically adjusts the insertion loss by 0.15dB to the baseline level, ensuring S-parameter measurement accuracy.

[0044] The server dynamically manages the adaptive operating conditions of the thermal isolation module. During low-temperature testing (e.g., -55°C), the server instructs the air curtain flow rate to increase to 12 m / s, strengthening the cold air barrier and suppressing ambient heat intrusion. During high-temperature testing (e.g., 200°C), the air curtain flow rate is maintained at 8 m / s, removing radiant heat from the probe surface through airflow. During non-test intervals, the air curtain flow rate is reduced to 6 m / s, balancing thermal insulation effectiveness with gas consumption. The server also coordinates the intelligent scheduling of RF measurement equipment. When testing high-frequency parameters (e.g., 20 GHz), the network analyzer is instructed to activate "high-frequency compensation mode" to offset the influence of probe parasitic parameters. The platform's workstation switching is also controlled by the server. During the calibration phase, a constant-temperature calibration plate is fixed to ensure probe contact position accuracy of ≤±5μm. During the device under test (DUT) testing phase, a robotic arm moves the DUT to the test position, repeating the "probe temperature control → pulse acquisition → dynamic compensation" process to output the temperature-compensated DUT RF parameters.

[0045] Taking the high temperature 200℃ test of GaN power amplifier DUT as an example, the complete test closed loop is as follows: in the calibration phase, the server controls the probe to heat up to 200℃ (TEC heating + air curtain insulation, temperature fluctuation ≤ 0.5℃), triggers a 5μs pulse to collect the normal temperature calibration piece S 21 Parameters (the original insertion loss increases by 0.15dB due to the high temperature of the probe), the dynamic compensation module calls the 200℃ insertion loss compensation coefficient to complete the correction; during the DUT test phase, the probe station moves the DUT to the test position, the probe is maintained at 200℃, and the DUT's S 21 The original value (e.g. -2.8dB) is then compensated to output the value "S of DUT at 200°C". 21 = -2.95dB (the actual value after eliminating the probe's high-temperature insertion loss interference). After the test, the server archives the calibration data, DUT test data, and module work log, and generates a test report that includes a temperature-S parameter curve, error analysis, and repeatability verification.

[0046] Through the above implementation method, this system uses the server to accurately coordinate various modules to solve the thermal interference problem between the probe and the calibration piece in traditional testing (the influence of heat exchange is reduced to <0.1℃ temperature drift), and realizes the effective reuse of normal temperature calibration pieces in a wide temperature range (replacing dedicated temperature control calibration pieces). By eliminating the dedicated temperature control module, the hardware cost is reduced by more than 60% and the calibration efficiency is increased by more than 30 times (the probe temperature control response time is <1 second, and the traditional solution is >30 seconds). Ultimately, the high-precision test goals of ≤0.03dB error and phase consistency ±0.5° after compensation for the full range of S parameter temperature drift from -55℃ to 200℃ are achieved.

[0047] In an embodiment of the present invention, the probe temperature adjustment module includes a thermoelectric cooler, a liquid cooling unit and a temperature sensor; the thermoelectric cooler and the liquid cooling unit are directly attached to the probe handle to achieve rapid temperature adjustment of the probe, with an adjustment rate of ≥15°C / s; the temperature sensor is embedded in the probe tip, and the temperature measurement accuracy is ±0.1°C.

[0048] In an embodiment of the present invention, for example, during the operation of the RF on-wafer test system, the server, as the core control node, implements full-process control of the thermoelectric cooler, liquid cooling unit, and temperature sensor of the probe temperature regulation module to meet the needs of rapid and precise adjustment of the probe temperature over a wide temperature range. After the system is started, the server first sends initialization instructions to the thermoelectric cooler and liquid cooling unit to verify the physical connection status of the two with the probe handle (confirming the attachment reliability through the hardware status feedback signal), and at the same time reads the reference zero point of the temperature sensor embedded in the probe tip (completing the calibration of the ±0.1°C measurement accuracy).

[0049] When performing a low-temperature test at -55°C, the server sends a cooling mode activation command to the thermoelectric cooler, utilizing its Peltier effect to absorb heat from the probe handle. Simultaneously, the liquid cooling unit activates, circulating coolant through the probe handle at high speed (the flow rate is dynamically adjusted by the server based on the temperature control algorithm). Together, these two functions achieve a cooling rate of ≥15°C / s. If the probe is initially at room temperature (25°C), the server uses a PID algorithm to analyze the 100Hz data stream transmitted by the temperature sensor (e.g., 10°C in the first second, -5°C in the second, and then stabilizing to -55°C in the sixth second), cooling the probe from 25°C to -55°C in just approximately 6 seconds. During this process, the temperature sensor continuously transmits data such as "-54.9°C → -55.1°C → -55.0°C." The server compares the deviations and fine-tunes the cooling power and coolant flow rate, ultimately stabilizing the probe at -55±0.3°C, meeting the required measurement accuracy of ±0.1°C.

[0050] When performing a high-temperature test at 200°C, the server switches the thermoelectric cooler to heating mode (reverse current generates heat), and the liquid cooling unit switches to "temperature control and heat dissipation" mode (adjusting the coolant flow to balance heat). The temperature sensor continuously sends back data such as "199.8°C→200.1°C→200.0°C". The server relies on a heating rate of ≥15°C / s to allow the probe to rise from 25°C to 200°C in about 12 seconds (at the same time, it instructs the thermal isolation module to raise the air curtain flow rate to 10m / s to isolate the ambient heat radiation). After the temperature sensor continuously feedbacks that the temperature is stable at 200±0.5°C for 100ms, the server determines that the temperature control is complete and provides a temperature-stable probe for subsequent testing links.

[0051] Through the above process, the server relies on the coordinated control of the thermoelectric cooler and liquid cooling unit, and the high-precision feedback of the temperature sensor to ensure that the probe can achieve rapid temperature adjustment of ≥15°C / s and steady-state control with an accuracy of ±0.1°C in the full range of -55°C to 200°C, laying a solid hardware foundation for wide-temperature range S-parameter calibration.

[0052] In an embodiment of the present invention, the pulse width of the radio frequency pulse signal emitted by the instantaneous pulse acquisition module is ≤5μs, and the radio frequency pulse signal is acquired within the thermal relaxation time window after the probe contacts the normal temperature calibration piece, and the thermal relaxation time is >5ms.

[0053] In an embodiment of the present invention, exemplarily, during the operation of the RF on-wafer test system, the server serves as the core control unit, and fully dominates the pulse emission and acquisition logic of the transient pulse acquisition module to accurately avoid the interference of thermal relaxation on the RF parameter measurement.

[0054] When the system enters the test phase, the server first sends a "probe drop" command to the carrier platform, driving the probe's vertical displacement until it contacts the surface of the room-temperature calibration plate. The pressure sensor integrated into the probe senses the moment of contact and immediately transmits a "contact trigger signal" back to the server. Upon receiving this signal, the server immediately issues a "fire pulse" command to the transient pulse acquisition module (pulse generator), strictly controlling its output to an ultra-narrow RF pulse width of ≤5μs (for example, a pulse signal with a pulse width of 3μs was output in actual testing).

[0055] At the same time, relying on the characteristic of "thermal relaxation time > 5ms" clearly stated in the technical briefing document, the server accurately controls the pulse timing through a nanosecond time synchronization mechanism: after the probe contacts the calibration piece, the thermal relaxation process of temperature fluctuations caused by heat transfer takes more than 5ms to significantly interfere with the measurement, and the pulse width is only at the μs level (far less than the thermal relaxation time). Therefore, the server forces the pulse to complete signal injection and RF parameter acquisition before the thermal relaxation process starts. At this time, the pulse window completely covers the initial stable section of the thermal relaxation heating curve, so that the temperature fluctuation of the calibration piece is always <0.1°C.

[0056] To test a high frequency device S 11 For example, the reflection coefficient: after the probe contacts the normal temperature calibration piece, the server triggers the pulse emission within 2μs, and the pulse lasts for 3μs to complete the signal injection; after the RF signal reflected by the calibration piece is transmitted to the RF measurement device through the probe, the server synchronizes the instruction device to complete the S within 1μs after the pulse ends. 11 The entire acquisition process takes less than 5μs, far earlier than the temperature drift caused by thermal relaxation (measurable fluctuations in the calibration chip temperature occur 5ms after thermal relaxation).

[0057] Through the above process, the server, by strictly limiting the pulse width and accurately scheduling the thermal relaxation timing, allows the instantaneous pulse acquisition module to complete data acquisition before the heat exchange interference takes effect, ensuring the original accuracy of the RF parameter measurement from the time dimension and providing reliable basic data for subsequent dynamic compensation links.

[0058] In an embodiment of the present invention, the dynamic compensation module has a built-in probe temperature-electrical characteristic mapping database, the electrical characteristics include impedance, insertion loss and phase, and the dynamic compensation module corrects the RF parameter measurement value in real time through interpolation calculation.

[0059] In an embodiment of the present invention, for example, when the RF on-wafer test system is running, the server fully controls the workflow of the dynamic compensation module, relying on the pre-loaded "probe temperature-electrical characteristic mapping database" and interpolation algorithm to achieve real-time correction of RF parameters. During the system startup phase, the server retrieves the database from the storage unit. This database is constructed by the "probe temperature-electrical characteristic calibration experiment" and covers the variation of probe impedance, insertion loss, and phase with temperature in the range of -55°C to 200°C (for example, at 200°C, the probe insertion loss increases by 0.15dB and the impedance increases by 2%, and at -55°C, the phase drift coefficient α = -0.02° / °C).

[0060] During the test, the server receives two key data simultaneously: the original measurement value of the RF parameters sent back by the RF measurement equipment (such as S 11 Reflection coefficient, S 21 transmission coefficient); the second is the real-time temperature of the probe uploaded by the probe temperature adjustment module (such as -55.1℃, 200.0℃). Taking the S11 reflection coefficient test at a low temperature of -55°C as an example: after the server obtains the real-time probe temperature of -55.1°C, it immediately extracts the electrical characteristic data at this temperature from the database. Compared with the 25°C benchmark, the impedance increases by 0.2Ω, the insertion loss increases by an additional 0.1dB, and the phase drift coefficient α = -0.02° / °C. Then, the interpolation calculation logic is activated. For the phase parameter, the formula ΔΦ = α(T)·ΔT (where ΔT is the difference between the real-time temperature and the 25°C benchmark, that is, -55.1-25 = -80.1°C) is substituted. The calculated phase correction amount ΔΦ = -0.02° / °C × (-80.1°C) = +1.602° is obtained, correcting the original phase error from +1.1° to within ±0.3°. For the insertion loss parameter, the server performs linear interpolation based on the "temperature-insertion loss" fitting curve, deducting the 0.1dB additional insertion loss introduced by the low temperature of the probe from the original measurement value, so that S 11 Reflection coefficient regression benchmark accuracy.

[0061] If the high temperature 200℃ test S 21Transmission coefficient, after the server obtains the probe temperature of 200℃, it calls the electrical characteristic data in the database that "insertion loss increases by 0.15dB and impedance increases by 2% at 200℃"; for the S 21 The dynamic compensation module first corrects the influence of impedance change through the impedance-transmission coefficient interpolation model, and then deducts the additional insertion loss of 0.15dB according to the "temperature-insertion loss" curve, and finally outputs the corrected S 21 value (such as -3.0dB) to ensure that it is consistent with the normal temperature reference.

[0062] Through the above process, the server uses the database as the basis and the interpolation algorithm as the tool to enable the dynamic compensation module to offset the interference of probe temperature fluctuations on RF parameters in real time during each test, providing algorithm-level guarantees for the accurate measurement of S parameters in a wide temperature range.

[0063] In an embodiment of the present invention, the thermal isolation module is an air curtain insulation device, which forms a directional airflow barrier around the probe through an annular compressed air nozzle, and the flow rate of the directional airflow barrier is 6-12m / s.

[0064] In an embodiment of the present invention, exemplarily, during the operation of the RF on-wafer test system, the server acts as the core control unit to implement full-process management of the airflow generation and flow rate regulation of the thermal isolation module (air curtain insulation device), and relies on the structural characteristics of the "annular compressed air nozzle + directional airflow barrier" to achieve thermal isolation between the probe and the environment.

[0065] When the system starts, the server sends an initialization command to the air curtain insulation device, driving the annular compressed air nozzle to self-check (confirming that the nozzle array is ventilating smoothly and the air pressure sensor is in normal condition), and then outputs 6m / s of compressed air to initially form a directional airflow barrier surrounding the probe. The airflow is evenly distributed along the axis of the probe, forming a basic insulation layer to weaken the heat exchange between the environment and the probe.

[0066] When performing a low-temperature test at -55°C, the server, in conjunction with the "target temperature -55°C" instruction from the probe temperature control module, simultaneously increases the air curtain flow rate to 10-12m / s: an annular compressed air nozzle ejects high-speed cold air, forming a dense barrier around the probe, blocking the reverse transfer of ambient heat to the low-temperature probe. For example, when testing a microwave device, after the probe is cooled to -55°C by the temperature control module, the server continuously monitors the probe temperature fluctuations (which must be stable within ±0.3°C) and offsets the interference of ambient thermal radiation through dynamic fine-tuning of the air curtain flow rate (for example, increasing it from 10m / s to 11m / s), ensuring that the probe maintains thermal stability under low-temperature conditions.

[0067] Switching to a high-temperature test scenario at 200°C, the server adjusts the air curtain flow rate to 8-10m / s. The airflow from the annular nozzle removes the radiant heat generated by the high temperature on the probe surface while preventing local airflow disturbances (affecting temperature uniformity) caused by excessive flow rate. For example, when testing a GaN power amplifier, after the probe is heated to 200°C by the TEC, the server precisely controls the air curtain flow rate (for example, maintaining 8m / s) and, in conjunction with the thermal isolation structure, ensures that probe temperature fluctuations remain ≤0.5°C, providing a stable thermal environment for RF parameter acquisition.

[0068] During the test interval or calibration phase, the server instructs the air curtain flow rate to drop back to 6m / s: at this time, the airflow output by the annular nozzle only maintains basic thermal insulation, balancing the thermal insulation effect and compressed air consumption. For example, during the calibration process of the normal temperature calibration piece, the air curtain runs at a flow rate of 6m / s, which not only prevents short-term fluctuations in ambient temperature from interfering with the probe, but also reduces system energy consumption, achieving a dynamic balance between energy saving and thermal insulation.

[0069] Through the above process, the server precisely controls the airflow velocity of the annular compressed air nozzle (dynamically switching between 6-12m / s) according to the thermal environment differences of the test conditions (low temperature, high temperature, and gap), allowing the directional airflow barrier to continuously surround the probe, physically blocking the heat exchange between the environment and the probe, and providing thermal protection for precise control of the probe temperature and stable collection of RF parameters.

[0070] Please refer to Figure 2 , Figure 2 A schematic flow chart of the steps of a radio frequency on-wafer testing method provided in an embodiment of the present invention, which is applied to the aforementioned radio frequency on-wafer testing system, includes:

[0071] Step S201: Keep the calibration plate at room temperature and adjust the probe temperature to the target temperature through the probe temperature adjustment module;

[0072] Step S202, controlling the probe to contact the normal temperature calibration piece, transmitting a radio frequency pulse signal through the transient pulse acquisition module and acquiring radio frequency parameters;

[0073] Step S203, dynamically correcting the radio frequency parameters based on the real-time temperature of the probe by a dynamic compensation module;

[0074] Step S204, switch to the device under test, repeat the steps of keeping the calibration plate at room temperature, adjusting the probe temperature to the target temperature through the probe temperature adjustment module, and dynamically correcting the RF parameters based on the real-time temperature of the probe through the dynamic compensation module to obtain the temperature-compensated RF parameters of the device under test.

[0075] In an embodiment of the present invention, illustratively, first, the calibration piece is kept at room temperature and the probe temperature is adjusted: the server sends a command to the carrier platform to fix the 25°C normal temperature calibration piece (standard ISS calibration piece) to the test station, and relies on environmental temperature control means (such as a constant temperature box or a room temperature stabilization device) to ensure that the temperature of the calibration piece is always maintained within the range of ambient room temperature fluctuation ≤±1°C. A "target temperature" command is simultaneously issued to the probe temperature adjustment module. Taking the low temperature -55°C test as an example, the server drives the thermoelectric cooler (TEC) to turn on the cooling mode, and the liquid cooling unit is linked to circulate and cool the probe handle; the temperature sensor at the tip of the probe sends back temperature data at a frequency of 100Hz, and the server runs the PID temperature control algorithm to dynamically adjust the TEC power and coolant flow rate, so that the probe is cooled from 25°C to -55°C at a rate of ≥15°C / s. During the process, the server instructs the thermal isolation module (air curtain insulation device) to increase the airflow velocity to 10m / s, and uses an annular compressed air nozzle to form a dense airflow barrier around the probe to block the intrusion of ambient heat. When the temperature sensor continuously feedbacks a temperature stable at -55±0.3℃ for 100ms, the server determines that the probe temperature meets the standard.

[0076] Subsequently, the probe contact and pulse collection are controlled: the server sends a "probe drop" command to the carrier platform, and the probe platform drives the probe to move vertically until it contacts the surface of the normal temperature calibration piece; the pressure sensor inside the probe senses the contact moment and sends a trigger signal back to the server. The server immediately instructs the instantaneous pulse acquisition module (pulse generator) to emit a RF pulse with a pulse width of 3μs (meeting the requirement of ≤5μs), and synchronously triggers the RF measurement equipment (network analyzer) to collect the RF parameters reflected / transmitted by the calibration piece (such as S 11 Since pulse acquisition is completed within the thermal relaxation time window after the probe contacts the calibration piece (thermal relaxation time > 5ms, while the pulse duration is only 3μs), the temperature fluctuation of the calibration piece is less than 0.1°C, ensuring the original acquisition accuracy of the RF parameters.

[0077] Next, dynamically compensate the RF parameters: the server obtains the real-time temperature (e.g. -55.1°C) from the probe temperature adjustment module, calls the built-in "probe temperature-electrical characteristic mapping database" of the dynamic compensation module, and extracts the probe's impedance offset (increase of 0.2Ω), insertion loss change (increase of 0.1dB), and phase drift coefficient (α=-0.02° / °C) at that temperature. 11 The server substitutes the original phase value into the phase compensation formula ΔΦ=α(T)·ΔT(ΔT=-55.1-25=-80.1℃) and calculates the phase correction amount +1.602°, correcting the original phase error from +1.1° to within ±0.3°; for the insertion loss parameter, the server deducts 0.1dB of additional insertion loss through the "temperature-insertion loss" curve interpolation, so that S 11 The reflection coefficient is regressed to the reference level to generate the calibrated RF parameters.

[0078] Finally, switch the device under test and repeat the process: the server instructs the platform robot to move the device under test (such as a GaN power amplifier) ​​to the test station and replace the normal temperature calibration plate. Repeat the above process: first, use the probe temperature control module to raise the probe temperature to 200℃ (TEC heating mode, air curtain flow rate adjusted to 8m / s for thermal insulation, temperature fluctuation ≤0.5℃); control the probe to contact the pad of the device under test, and emit a 5μs pulse to collect S 21 Transmission coefficient; Dynamic compensation module is based on the electrical characteristics of the probe at 200℃ (insertion loss increased by 0.15dB, impedance increased by 2%) to S 21 The original values ​​are interpolated and corrected, and the precise RF parameters of the device under test after temperature compensation are finally output.

[0079] Through the above process, the server coordinates each module to complete the full closed loop of "calibration of calibration piece benchmark → parameter testing of device under test", and realizes accurate measurement of RF parameters in a wide temperature range of -55℃ to 200℃, avoiding the thermal interference and temperature drift problems of traditional testing and reducing system complexity and cost through module reuse.

[0080] In an embodiment of the present invention, the target temperature is adjusted within a range of -55°C to 200°C, and the time taken by the probe temperature adjustment module to adjust the probe temperature to the target temperature is ≤1 second.

[0081] In an exemplary embodiment of the present invention, during the RF on-wafer test method, the server directs the temperature control process of the probe temperature adjustment module, ensuring that the target temperature (-55°C to 200°C) is adjusted within 1 second. Upon receiving the "target temperature" command, the server first reads the current temperature from the probe tip temperature sensor.

[0082] Taking the low-temperature scenario (target temperature -55°C) as an example, if the probe is initially pre-cooled to -40°C (a temperature difference of 15°C from the target), the server immediately sends a forced cooling command to the thermoelectric cooler, linking the liquid cooling unit to accelerate the circulation of the coolant in the probe handle, driving the probe to cool down at a rate of not less than 15°C / s; the temperature sensor sends back temperature data in real time at a frequency of 100Hz (such as -41°C feedback at 10ms, -50°C feedback at 50ms, and -55°C feedback at 90ms), and the server runs the PID algorithm to dynamically correct the thermoelectric cooler power and the liquid cooling unit flow rate, stabilizing the probe temperature to -55±0.3°C within 1 second, and at the same time instructing the thermal isolation module to increase the air curtain flow rate to 10m / s to enhance the thermal insulation effect in the low-temperature environment.

[0083] Switch to the high-temperature scenario (target temperature 200°C). If the current temperature of the probe is 185°C (15°C different from the target temperature), the server instructs the thermoelectric cooler to switch to heating mode, and the liquid cooling unit adjusts the coolant flow to balance the heat (to prevent the probe from overheating). The probe heats up at a rate of 15°C / s, and the temperature sensor continuously feeds back data (such as 186°C at 20ms, 195°C at 60ms, and 200°C at 100ms). The server simultaneously adjusts the thermal isolation module (the air curtain flow rate is adjusted to 8m / s to block ambient heat radiation) to stabilize the probe at 200±0.5°C within 1 second.

[0084] For temperature adjustments across different temperature ranges (such as jumping from -55°C to 150°C), the server adopts a "segmented temperature control" strategy: first, the thermoelectric cooler is driven to heat and the liquid cooling unit is stopped, so that the probe is heated at a rate of 15°C / s, and 15°C adjustment is completed every 1 second; when the temperature sensor feedback probe reaches 135°C (a temperature difference of 15°C from the target temperature of 150°C), the server fine-tunes the thermoelectric cooler power to ensure that the temperature rises accurately from 135°C to 150°C within the last 1 second. The entire process uses the PID algorithm and hardware rate characteristics to ensure that each temperature difference adjustment of ≤15°C is completed within 1 second.

[0085] Through the above-mentioned precise scheduling, the server relies on the "≥15℃ / s adjustment rate" of the probe temperature adjustment module and the ±0.1℃ measurement accuracy of the temperature sensor to achieve 1-second temperature control with a single-stage temperature difference of ≤15℃ in the full range of -55℃ to 200℃, providing a stable thermal foundation for subsequent pulse acquisition and dynamic compensation links, and meeting the "wide temperature range and high efficiency" testing requirements.

[0086] In an embodiment of the present invention, the pulse width of the radio frequency pulse signal is ≤5 μs, and the acquisition is completed within a thermal relaxation time window after the probe contacts the normal temperature calibration piece, and the thermal relaxation time is >5 ms.

[0087] In an embodiment of the present invention, exemplarily, when executing the RF on-wafer test method, the server dominates the full timing control of the instantaneous pulse acquisition: when the carrier platform drives the probe to fall and contact the normal temperature calibration piece, the pressure sensor inside the probe sends the "contact trigger signal" back to the server in real time; the server immediately issues a transmission instruction to the instantaneous pulse acquisition module, controlling it to output an RF pulse with a pulse width of 3μs (meeting the "pulse width ≤ 5μs" requirement).

[0088] At the same time, the server relies on the "thermal relaxation time > 5ms" feature clearly stated in the technical briefing document to accurately control the acquisition timing through a nanosecond time synchronization mechanism: after the probe contacts the calibration piece, the thermal relaxation process of temperature fluctuations caused by heat transfer takes more than 5ms to significantly interfere with the measurement, and the pulse width is only at the μs level (much smaller than the thermal relaxation time). Therefore, the server forces the pulse to complete signal injection and RF parameter acquisition before the thermal relaxation process starts. For example, when testing S 11 When the reflection coefficient is measured, the probe emits a pulse within 2μs after contact, completes signal injection within 3μs, and the RF measurement equipment completes S within 1μs after the pulse ends. 11 The entire parameter acquisition process takes less than 5μs, which is much earlier than the temperature drift caused by thermal relaxation (the temperature of the calibration piece will not show measurable fluctuations until 5ms later). This ensures that the temperature fluctuation of the calibration piece is always <0.1℃, providing high-precision raw data for the subsequent dynamic compensation link.

[0089] In an embodiment of the present invention, the dynamic correction is performed by interpolating and correcting the radio frequency parameters by calling a pre-stored probe temperature-impedance relationship curve;

[0090] The interpolation correction includes phase compensation. The phase compensation formula is ΔΦ=α(T)·ΔT, where ΔΦ is the phase correction amount, α(T) is the temperature correlation coefficient, and ΔT is the difference between the real-time temperature of the probe and the reference temperature.

[0091] In the embodiment of the present invention, for example, when performing dynamic correction, the server first obtains the real-time temperature of the probe from the probe temperature adjustment module (such as -55.1°C in the test), and at the same time receives the original value of the RF parameter returned by the RF measurement device (such as S 11 The server then calls the pre-stored probe temperature-impedance relationship curve and performs interpolation correction on the part of the RF parameters affected by the probe impedance change. If the database records that the probe impedance at -55°C increases by 0.2Ω compared to the 25°C benchmark, the server will use the impedance-RF parameter interpolation model to deduct the impedance increment from the S 11 Interference of reflection coefficient.

[0092] For the phase compensation link, the server extracts the temperature correlation coefficient α(T) corresponding to the current temperature from the "probe temperature-electrical characteristic mapping database" (for example, α(T) = -0.02° / °C at -55.1°C), and then calculates the difference ΔT between the probe's real-time temperature and the 25°C reference temperature (in this scenario, ΔT = -55.1-25 = -80.1°C). Substitute α(T) and ΔT into the phase compensation formula ΔΦ = α(T)·ΔT to obtain the phase correction value (in this example, ΔΦ = -0.02° / °C × (-80.1°C) = +1.602°). Finally, the server adds this correction value to S 11The original phase value corrects the original +1.1° phase error to within ±0.3°, completing the dynamic and precise correction of the RF parameters.

[0093] In an embodiment of the present invention, the method further includes:

[0094] When adjusting the probe temperature, a directional airflow barrier is opened through the thermal isolation module to reduce heat exchange between the probe and the external environment. The flow rate of the directional airflow barrier is 6-12 m / s.

[0095] In an embodiment of the present invention, for example, when adjusting the probe temperature, the server synchronously instructs the thermal isolation module (air curtain insulation device) to open the directional airflow barrier. For low-temperature adjustment scenarios (such as the target temperature of -55°C), the server drives the annular compressed air nozzle to output a high-speed airflow of 10-12m / s to form a dense cold air barrier around the probe. When the probe temperature adjustment module (thermoelectric cooler + liquid cooling unit) lowers the probe from 25°C to -55°C, the high-speed airflow blocks the reverse transfer of ambient heat to the low-temperature probe, and cooperates with the PID temperature control algorithm to complete the cooling of the probe within 1 second and the temperature fluctuation is ≤0.3°C.

[0096] When switching to a high-temperature regulation scenario (e.g., a target temperature of 200°C), the server adjusts the air curtain flow rate to 8-10m / s. As the probe is heated by the thermoelectric cooler, the airflow continuously removes the radiant heat from the probe surface, preventing ambient thermal radiation from interfering with temperature control accuracy and excessive flow rate from causing local temperature unevenness on the probe. For example, when the probe is heated from 25°C to 200°C, an 8m / s airflow keeps the temperature fluctuation ≤0.5°C, ensuring the stability of 1-second temperature rise.

[0097] If it is in the adjustment gap or calibration stage (such as the normal temperature calibration piece calibration process), the server instructs the air curtain flow rate to drop back to 6m / s: at this time, the airflow only maintains the basic insulation layer, while weakening the impact of short-term fluctuations in ambient temperature on the probe, reducing compressed air consumption and achieving a dynamic balance between energy saving and thermal insulation.

[0098] By precisely controlling the air curtain flow rate (dynamically switching between 6-12m / s), the server allows the directional airflow barrier to remain effective throughout the probe temperature adjustment process, physically reducing the heat exchange between the probe and the external environment, and providing thermal protection for "1-second precise temperature control" and wide temperature range testing.

[0099] For illustrative purposes, the foregoing description has been made with reference to specific embodiments. However, the above illustrative discussion is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. Numerous modifications and variations are possible in light of the above teachings. These embodiments have been selected and described in order to best illustrate the principles of the present disclosure and its practical application, thereby enabling those skilled in the art to best utilize the present disclosure and to utilize various embodiments with various modifications as appropriate for the specific application contemplated.

Claims

1. A radio frequency on-wafer test system, characterized in that: include: Probe temperature adjustment module, used to independently adjust the probe temperature to the target value; The instantaneous pulse acquisition module is used to transmit a radio frequency pulse signal and acquire radio frequency parameters when the probe contacts the normal temperature calibration piece; A dynamic compensation module, configured to dynamically correct the radio frequency parameters based on the real-time temperature of the probe; Thermal isolation module, used to reduce heat exchange between the probe and the external environment; Radio frequency measurement equipment, used to collect and analyze the radio frequency parameters; The carrying platform is used to carry the normal temperature calibration piece or the device to be tested.

2. The RF on-wafer test system according to claim 1, characterized in that: The probe temperature adjustment module includes a thermoelectric cooler, a liquid cooling unit and a temperature sensor; the thermoelectric cooler and the liquid cooling unit are directly attached to the probe handle to achieve rapid probe temperature adjustment, with an adjustment rate of ≥15°C / s; the temperature sensor is embedded in the probe tip, and the temperature measurement accuracy is ±0.1°C.

3. The RF on-wafer test system according to claim 1, wherein: The radio frequency pulse signal emitted by the instantaneous pulse acquisition module has a pulse width of ≤5μs, and the radio frequency pulse signal is acquired within a thermal relaxation time window after the probe contacts the normal temperature calibration piece, and the thermal relaxation time is >5ms.

4. The RF on-wafer test system according to claim 1, wherein: The dynamic compensation module has a built-in probe temperature-electrical characteristic mapping database, where the electrical characteristics include impedance, insertion loss, and phase. The dynamic compensation module corrects the radio frequency parameter measurement values ​​in real time through interpolation calculation.

5. The RF on-wafer test system according to claim 1, characterized in that: The thermal isolation module is an air curtain insulation device, which forms a directional airflow barrier around the probe through an annular compressed air nozzle, and the flow rate of the directional airflow barrier is 6-12m / s.

6. A radio frequency on-wafer testing method, characterized in that: Applicable to the RF on-wafer test system according to any one of claims 1 to 5, the method comprising: Keep the calibration piece at room temperature and adjust the probe temperature to the target temperature through the probe temperature adjustment module; The control probe is brought into contact with the normal temperature calibration piece, and a radio frequency pulse signal is emitted through the instantaneous pulse acquisition module to acquire radio frequency parameters; Dynamically correcting the radio frequency parameters based on the real-time temperature of the probe by a dynamic compensation module; Switch to the device under test, and repeat the steps of keeping the calibration plate at room temperature, adjusting the probe temperature to the target temperature through the probe temperature adjustment module, and dynamically correcting the RF parameters based on the real-time temperature of the probe through the dynamic compensation module to obtain the temperature-compensated RF parameters of the device under test.

7. The RF on-wafer testing method according to claim 6, characterized in that: The target temperature is adjusted in a range of -55°C to 200°C, and the time taken by the probe temperature adjustment module to adjust the probe temperature to the target temperature is ≤1 second.

8. The RF on-wafer testing method according to claim 6, wherein: The pulse width of the radio frequency pulse signal is ≤5μs, and the acquisition is completed within the thermal relaxation time window after the probe contacts the normal temperature calibration piece, and the thermal relaxation time is greater than 5ms.

9. The RF on-wafer testing method according to claim 6, characterized in that: The dynamic correction is performed by interpolating and correcting the radio frequency parameters by calling a pre-stored probe temperature-impedance relationship curve; The interpolation correction includes phase compensation. The phase compensation formula is ΔΦ=α(T)·ΔT, where ΔΦ is the phase correction amount, α(T) is the temperature correlation coefficient, and ΔT is the difference between the real-time temperature of the probe and the reference temperature.

10. The radio frequency on-wafer testing method according to claim 6, characterized in that: The method further comprises: When adjusting the probe temperature, a directional airflow barrier is opened through the thermal isolation module to reduce heat exchange between the probe and the external environment. The flow rate of the directional airflow barrier is 6-12 m / s.

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