Automatic detection equipment and method for radio frequency matcher

Abstract

The invention relates to automatic detection equipment and method for a radio frequency matcher, and belongs to the technical field of semiconductor equipment detection. In automatic detection of the equipment radio frequency matcher, a matching range detection circuit is connected with a radio frequency switch, a radio frequency power supply, a probe and the radio frequency matcher through a radio frequency coaxial cable or a radio frequency connector; the simulation load module comprises a first impedance tuning module and a second impedance tuning module. The first impedance tuning module and the second impedance tuning module each comprise a vacuum adjustable capacitor and an inductor, wherein the capacitance value of the vacuum adjustable capacitor is regulated and controlled by a stepping motor. The absorption load module is connected with the probe and the radio frequency switch through a radio frequency coaxial cable or a radio frequency connector. The detection method comprises the following steps of: compensating and absorbing impedance offset of the load in a self-calibration stage, adjusting four groups of capacitor pole end combinations in a matching range test, collecting impedance data, matching time, detecting a standing-wave ratio and testing stability. According to the invention, full-automatic detection is realized by replacing a process chamber, and the problem that the dynamic change of impedance cannot be simulated is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor equipment detection, and particularly relates to a radio frequency matching device automatic detection equipment and method. BACKGROUND

[0002] In a semiconductor ICP or CCP process equipment, a radio frequency matching device is a core component for adjusting impedance matching between a radio frequency power supply and a process chamber. Impedance mismatching can cause radio frequency power transmission efficiency to decrease, plasma excitation to fail, and even damage to the equipment due to excessively high reflected power, so the performance of the radio frequency matching device directly determines the stability and yield of the semiconductor manufacturing equipment. At present, detection of the radio frequency matching device mainly relies on two types of technologies, namely manual detection combined with a process chamber and a fixed load simulation method. A technician manually adjusts parameters of the matching device, passes different gases into the process chamber and adjusts the pressure, and observes a plasma ignition state, but this detection method has a long cycle, takes several hours for a single test, cannot simulate an ignition stage, the chamber impedance has a large change from high impedance to low impedance in nanoseconds to microseconds, the test is greatly affected by a state of the process chamber, and the test result is not reproducible; the fixed load simulation method uses a 50Ω fixed impedance load to replace the process chamber, and measures S parameters through a network analyzer, but this method can only detect a static impedance matching range, cannot verify a scenario in which a load impedance suddenly decreases from kilo-ohms to hundreds of ohms at a plasma ignition moment, cannot verify impedance continuous fluctuation caused by process gas proportion and other process condition changes, and cannot monitor response speed and stability of the matching device under a dynamic load; researchers propose to simulate the load through a parallel LC circuit, but this method still relies on mechanical adjustment of a capacitor, and the adjustment delay is in milliseconds, which is 100 times different from a real process chamber ignition time.

[0003] Therefore, the prior art urgently needs a radio frequency matching device automatic detection equipment and method. SUMMARY

[0004] Based on problems existing in the prior art, the present application provides a radio frequency matching device automatic detection equipment and method to solve the problems in the prior art that the process chamber dynamic impedance characteristics cannot be automatically simulated, multi-port testing is not supported, and self-calibration is not provided, resulting in that performance evaluation of the radio frequency matching device is not comprehensive and test efficiency is low.

[0005] To solve the above technical problems, the present application specifically provides the following technical solutions: A radio frequency matching device automatic detection equipment includes a matching range detection circuit, a simulated load module, an absorption load module, and a control module. The matching range detection circuit comprises a radio frequency power supply, a first probe, a radio frequency matching device, a second probe, a third probe, a radio frequency switch S1 and a radio frequency switch S2; the radio frequency power supply is connected to the first probe through a radio frequency coaxial cable, the first probe is connected to an input end of the radio frequency matching device, a first output end of the radio frequency matching device is connected to the second probe, a second output end of the radio frequency matching device is connected to the third probe, the second probe is connected to a common end of the radio frequency switch S2, the third probe is connected to a common end of the radio frequency switch S1, and the three radio frequency switches S1, S2 and S3 are controlled by a control module; the matching range detection circuit is used for establishing a radio frequency signal path and collecting impedance parameters; The analog load module comprises a first impedance tuning module and a second impedance tuning module, and each of the first impedance tuning module and the second impedance tuning module comprises a vacuum adjustable capacitor and an inductor; the first impedance tuning module comprises vacuum adjustable capacitors C1 and C2 and a ground inductor L1 connected in parallel, and the second impedance tuning module comprises vacuum adjustable capacitors C3 and C4 and a ground inductor L2 connected in parallel; the analog load module is used for dynamically simulating the impedance characteristics of a process chamber. The absorbing load module comprises a probe and an absorbing load DL; the probe is connected to the absorbing load DL, and the absorbing load DL is grounded; the absorbing load module is used for providing a reference impedance and realizing self-calibration. The control module is used for controlling the on-off of the radio frequency switch, adjusting the capacitance value and monitoring the probe data.

[0006] Further, the vacuum adjustable capacitor in the analog load module has a capacitance value range of 0-200 pF, and the adjustment mode is a stepping motor, a relay or a voltage-controlled diode.

[0007] Further, the control module comprises a microcontroller, a capacitance adjustment element and a communication control circuit for adjusting the capacitance element.

[0008] Further, the capacitors of the analog load module are interconnected through a metal connecting strip, and the inductors are grounded.

[0009] Further, the Load end of the radio frequency switch S3 is connected to the analog load module, and the Com end is connected to the absorbing load module.

[0010] Further, the control module further comprises a storage module and an output module, the storage module is used for recording the capacitance configuration state and the impedance data, the output module comprises a local output module and a remote output module, and supports local visual Smith circle diagram and remote structured data output.

[0011] The application further provides a radio frequency matching device automatic detection method applied to the device and comprising the following steps: Step S1, self-calibration: the radio frequency switch S3 is switched to the Open port, the absorbing load impedance offset is detected, and the capacitance is adjusted for compensation; Step S2, matching range test: in the off state of the radio frequency power supply, adjust the four groups of extreme combinations of C1-C4 to 0% / 100%, collect impedance data; Step S3, matching time and stability test: adjust the simulated load impedance according to the us-level preset curve, simulate the glow stage of the process chamber, and detect the standing wave ratio and output port data.

[0012] Further, the four groups of capacitor combinations are: C1_DUT=0% + C2_DUT=0%; C1_DUT=0% + C2_DUT=100%; C1_DUT=100% + C2_DUT=0%; C1_DUT=100% + C2_DUT=100%.

[0013] Further, the simulated load impedance adjusted according to the preset curve includes pre-ionization stage impedance Z1, breakdown stage impedance Z3 and steady state stage impedance Z4; in the test, the voltage and current data of the output ports Port#1 and Port#2 are collected in real time through the second probe and the third probe; in the stability test, the threshold value of the standing wave ratio VSWR is less than or equal to 1.2.

[0014] Further, the difference value δ of the self-calibration stage is stored in the control module, and the impedance curve data is derived from the actual process chamber parameters.

[0015] The present application has the following beneficial effects compared with the prior art: the present application reproduces the impedance environment in a complex process chamber through an adjustable simulated load module, avoids the use cost and maintenance problem of a real process chamber, improves the test efficiency, replaces the scheme of testing a radio frequency matching device with a process chamber, and realizes full-automatic testing of the process chamber; the control module adjusts the capacitance value within 1-100 μs according to the preset curve, truly restores the impedance transition process in the plasma glow stage, improves the matching stability detection accuracy, and accurately simulates the microsecond-level impedance change; the control module adjusts C3_DUT to 0%, adjusts C1_DUT and C2_DUT to 0% and 100% respectively, and combines them in pairs to form four combinations, which completely detects the impedance matching range of the radio frequency matching device in the four quadrants of the Smith chart, the four groups of extreme capacitance combinations comprehensively cover the matching boundary, and solve the problem that the prior art only tests the central area; regularly detect the absorption load DL impedance difference value δ and automatically compensate, ensure that the test precision error is small in long-term use, and the self-calibration mechanism compensates for the aging deviation of the equipment; the multi-port radio frequency matching device can be compatible with the test by increasing the number of links, and the simulated load capacitor can be replaced by a relay or a voltage-controlled diode, the modular design supports flexible expansion, and is suitable for high-frequency scenes. BRIEF DESCRIPTION OF DRAWINGS

[0016] To more clearly illustrate the embodiments of the present invention or the technical solutions in 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 merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the automatic detection device for radio frequency matching devices in Example 1; Figure 2 This is a schematic diagram of the test status of a dual-output RF matching circuit. Figure 3 This is a schematic diagram of the data from the four points where the matching range test output C3=0%. Detailed Implementation

[0018] 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.

[0019] The technologies involved in this application will first be described in conjunction with the accompanying drawings. It should be noted that the following descriptions of various technologies are only for the purpose of making the content of this application easier to understand and do not constitute a limitation on the scope of protection of this application; furthermore, the embodiments and features in the embodiments of this application can be combined with each other unless otherwise specified. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] Example One like Figure 1 As shown, this embodiment provides an automatic detection device for radio frequency matching devices, including a matching range detection circuit 10, an analog load module 20, an absorption load module 30, and a control module 40.

[0021] The matching range detection circuit 10 comprises a radio frequency power supply 101, a first probe 102, a radio frequency matcher 103, a second probe 104, a third probe 105, a radio frequency switch S1 and a radio frequency switch S2. The radio frequency power supply 101 is used to generate a radio frequency signal of a specific frequency and a specific power, the first probe 102 is used to collect a specific radio frequency parameter, the radio frequency matcher 103 is used for testing, the second probe 104 and the third probe 105 are used to collect a specific radio frequency parameter, the radio frequency switch S1 and the radio frequency switch S2 are single-pole double-throw radio frequency switches; the radio frequency power supply 101 is connected to the first probe 102 through a radio frequency coaxial cable or a radio frequency connector, and the first probe 102 is connected to an input end of the radio frequency matcher 103.

[0022] The analog load module 20 is connected to the second probe 104 and the third probe 105 through a radio frequency coaxial cable, and comprises a first impedance tuning module 201A and a second impedance tuning module 201B. The first impedance tuning module 201A comprises a vacuum adjustable capacitor C1, a vacuum adjustable capacitor C2 and an inductor L1; the second impedance tuning module 201B comprises a vacuum adjustable capacitor C3, a vacuum adjustable capacitor C4 and an inductor L2. C1, C2 and L1 are interconnected through a metal connecting strip, and L1 is grounded; C3, C4 and L2 are interconnected, and L2 is grounded. C2 and C3 are connected to a Load end of a radio frequency switch S3 through a metal connecting strip; in a high-frequency application scenario, the inductor can be replaced by a microstrip line, and in a low-frequency application scenario, the inductor is a fixed metal piece (such as a spiral type or a corner type).

[0023] The absorbing load module 30 comprises a probe 301 and an absorbing load DL. The probe 301 is connected to a Com port of the radio frequency switch S3 and connected to the absorbing load DL through a radio frequency coaxial cable. The absorbing load DL is grounded.

[0024] The control module 40 comprises a microcontroller and a capacitor adjustment element.

[0025] Specifically, the capacitor adjustment element comprises stepping motors M1-M4. The control module 40 controls the switching of the radio frequency switch S1, the radio frequency switch S2 and the radio frequency switch S3 and the stepping adjustment of the stepping motors M1-M4 based on the microcontroller. The probes collect impedance amplitude and phase angle parameters under four groups of combinations in real time, and transmit the parameters to the control module 40 through an ADC converter.

[0026] Specifically, the capacitor adjustment mode can also be a relay or a voltage-controlled diode adjustment, and the capacitance value range is 0-200pF. In addition to the stepping motors M1-M4, the capacitor adjustment element can also be a relay or a voltage-controlled diode.

[0027] The technical effect of the above scheme is that the adjustable analog load replaces the fixed load, solving the problem that the prior art relies on a process chamber.

[0028] Example Two The embodiment provides a radio frequency matching device automatic detection equipment, and on the basis of the first embodiment, a radio frequency matching device 103 output port is a multi-port, specifically, a radio frequency matching device 103 port is Port#1 and Port#2, a control module 40 further includes a storage module and an output module, the storage module includes an embedded Flash memory or an external database MySQL, the storage module is used for storing original impedance data corresponding to each group of combinations, a timestamp and a capacitor configuration state, the output module includes a local output module and a remote output module, the local output module is used for outputting impedance data visualization Smith circle graph trajectories under four groups of capacitor combinations, and the remote output module is used for outputting structured data to a remote system.

[0029] The technical effect of the above technical scheme is that the impedance matching boundary range of the radio frequency matching device at Port#1 can be intuitively displayed, automatic processing and analysis are facilitated, impedance matching range boundary range testing can be performed using Port#2, and meanwhile, the radio frequency matching device can be extended to a multi-port such as a 4-port matching device, and corresponding link components can be added accordingly.

[0030] Example Three The embodiment provides a radio frequency matching device automatic detection equipment, and on the basis of the first embodiment, a radio frequency matching device 103 output port is a multi-port, specifically, a radio frequency matching device 103 port is Port#1 and Port#2, a control module 40 further includes a storage module and an output module, the storage module includes an embedded Flash memory or an external database MySQL, the storage module is used for storing original impedance data corresponding to each group of combinations, a timestamp and a capacitor configuration state, the output module includes a local output module and a remote output module, the local output module is used for outputting impedance data visualization Smith circle graph trajectories under four groups of capacitor combinations, and the remote output module is used for outputting structured data to a remote system.

[0031] The technical effect of the above scheme is that the impedance change in the simulated ignition stage is adjusted at the us level, and the problem of mechanical delay in a high-frequency scene is solved.

[0032] Example Four The embodiment provides a radio frequency matching device automatic detection method, which is applied to a radio frequency matching device automatic detection equipment, and the automatic detection method specifically includes the following steps. Step S1, self-calibration: controlling a radio frequency switch to detect an absorption load DL impedance, if a preset value is deviated, calculating a difference delta, and adjusting a capacitor compensation; Step S2, test matching range: controlling a switch to select a gate, adjusting a simulation load capacitor combination, and collecting impedance data through a probe, when a radio frequency power supply is in an OFF state; Step S3, test matching time and stability: controlling a simulation load impedance to change according to a preset curve, and detecting whether a standing wave ratio is lower than a threshold value in a us level simulation ignition stage.

[0033] The technical effects of the above scheme are that the problem that the existing method cannot automatically simulate the ignition stage is solved.

[0034] Example Five The embodiment provides an automatic detection method of a radio frequency matcher, and uses the automatic detection equipment of the radio frequency matcher in the embodiment 2. The specific steps include the following. In step S1, self-calibration: the radio frequency power supply 101 is in an OFF state, the microcontroller controls the radio frequency switch S3 to connect the probe 301 to an open port, the probe 301 detects whether the impedance of the absorption load DL is located at a preset impedance value, if there is a difference between the preset impedance value, a difference value delta is calculated, the stepper motors M1, M2, M3 and M4 are controlled to adjust the vacuum adjustable capacitors C1-C4, the difference between the preset impedance value is compensated, and the change parameters of M1 to M4 are stored after the compensation is completed. In step S2, test the matching range: the radio frequency power supply 101 is in an OFF state, the radio frequency switch S1 is switched to an open port, the radio frequency switch S2 is switched to a load, the C3_DUT is adjusted to 0%, the C1_DUT and the C2_DUT are adjusted to 0% and 100% respectively, and four combinations are obtained by two-by-two combination. In the preferred embodiment, the control module adjusts the C3_DUT to 0%, adjusts the C1_DUT and the C2_DUT to 0% and 100% respectively, and four combinations are obtained by two-by-two combination. The second probe 104 collects the impedance values, and the control module stores and outputs the impedance values. Alternatively, the radio frequency switch S1 is switched to a load, and the radio frequency switch S2 is switched to an open port. The two methods differ in that different output ports are tested, and the same effect is achieved. It should be further pointed out that the control module adjusts the C3_DUT to 0%, adjusts the C1_DUT and the C2_DUT to 0% and 100% respectively, and four combinations are obtained by two-by-two combination. The second probe 104 collects the impedance values of the four combinations and stores and outputs the impedance values through the control module. The control module adjusts the C3_DUT to 100%, adjusts the C1_DUT and the C2_DUT to 0% and 100% respectively, and four combinations are obtained by two-by-two combination. The matching range test outputs the matching range data of C3=0% and the data of C3=100%. As shown in FIG. 6, the data of the four points of C3=0% and the data of C3=100% are similar. Figure 3

[0035] ​Step S3, Testing Matching Time and Stability: RF switch S3 is switched to Load, RF switches S1 and S2 are switched to Load, and M1-M4 is controlled to adjust the capacitance of vacuum adjustable capacitors C1-C4. The second probe 104 and the third probe 105 detect and calculate whether the impedance value of the analog load module 20 is the preset impedance value Z1 in the pre-ionization stage. If it is not Z1, M1-M4 is used to continue adjusting until the preset impedance value Z1 is reached. After adjustment, the compensation difference value δ is the compensated impedance value Z2. RF matching device 103 is adjusted to automatic matching mode. The microcontroller controls the RF power supply 101 to output the preset power at the preset operating frequency. The microcontroller controls M1-M4 to adjust the overall impedance of the analog load module 20 according to the preset curve to the breakdown stage impedance value Z3. After adjusting to Z3, it is adjusted according to the preset curve to the steady-state stage impedance value Z4. The first probe 102 detects whether the VSWR is lower than the preset VSWR Vswr within a preset time to determine whether the RF matching device 103 has completed matching. The preset impedance values ​​Z2 are adjusted to Z3 and Z4, both at the microsecond level, to simulate the drastic impedance changes during the ignition phase of the plasma process chamber. The preset impedance values ​​and Z4 can be adjusted according to different process chambers, and the adjustment values ​​are derived from measured values. Simultaneously, the second probe 104 and the third probe 105 record and store the VI data of the output ports Port#1 and Port#2 of the RF matching unit 103 during the impedance change from Z2 to Z4 of the simulated load module 20.

[0036] Specifically, the step of adjusting C1_DUT and C2_DUT to 0% and 100% respectively, and combining them in pairs, results in four combinations: Combination 1: C1_DUT=0% + C2_DUT=0%, Combination 2: C1_DUT=0% + C2_DUT=100%, Combination 3: C1_DUT=100% + C2_DUT=0%, Combination 4: C1_DUT=100% + C2_DUT=100%.

[0037] like Figure 2 As shown, the working state of the RF matching unit 103 during the test is as follows: Port#1 is connected to RF switch S1, and Port#2 is connected to RF switch S2; the vacuum adjustable capacitors C1-C4 and inductors L1 and L2 in the analog load module 20 constitute two sets of independent adjustable circuits.

[0038] The technical effects of the above solution are as follows: by combining four sets of extreme capacitance values, the impedance matching boundary range of the RF matching unit 103 at the output ports Port#1 and Port#2 is fully detected, providing data support for the performance evaluation of the matching unit; self-calibration solves the impedance shift caused by the absorption load during long-term use.

[0039] In summary, the application provides a detection scheme capable of automatically simulating dynamic impedance characteristics of a process chamber, supporting multi-port testing and having a self-calibration function, so as to solve the problems of incomplete performance evaluation of a radio frequency matching device and low testing efficiency.

[0040] The principles and implementation manners of the present application are described herein by using specific examples, and the above examples are only used to help understand the method and core idea of the present application. The above description is only the preferred implementation manner of the present application. It should be noted that, due to the limited expression of the text, there are infinite specific structures in the objective world. For ordinary skilled persons in the technical field, some improvements, refinements or changes can be made without departing from the principles of the present application, and the above technical features can also be combined in an appropriate manner. These improvements, refinements, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, shall be regarded as the protection scope of the present application.

Claims

1. An automatic testing device for radio frequency matching devices, characterized in that, The automatic detection device comprises a matching range detection circuit (10), an analog load module (20), an absorption load module (30) and a control module (40): The matching range detection circuit (10) comprises a radio frequency power supply (101), a first probe (102), a radio frequency matcher (103), a second probe (104), a third probe (105), a radio frequency switch S1 and a radio frequency switch S2; the radio frequency power supply (101) is connected to the first probe (102) through a radio frequency coaxial cable, the first probe (102) is connected to the input end of the radio frequency matcher (103), the first output end of the radio frequency matcher (103) is connected to the second probe (104), the second output end of the radio frequency matcher (103) is connected to the third probe (105), the second probe (104) is connected to the common end of the radio frequency switch S2, the third probe (105) is connected to the common end of the radio frequency switch S1, and the three radio frequency switches S1, S2 and S3 are controlled by the control module; the matching range detection circuit (10) is used for establishing a radio frequency signal path and collecting impedance parameters; The analog load module (20) comprises a first impedance tuning module (201A) and a second impedance tuning module (201B), and the first impedance tuning module (201A) and the second impedance tuning module (201B) each comprise a vacuum adjustable capacitor and an inductor; the first impedance tuning module (201A) comprises vacuum adjustable capacitors C1 and C2 and a ground inductor L1 connected in parallel, and the second impedance tuning module (201B) comprises vacuum adjustable capacitors C3 and C4 and a ground inductor L2 connected in parallel; the analog load module (20) is used for dynamically simulating process chamber impedance characteristics; The absorption load module (30) comprises a probe (301) and an absorption load DL; the probe (301) is connected to the absorption load DL, and the absorption load DL is grounded; the absorption load module (30) is used for providing a reference impedance and realizing self-calibration; The control module (40) is used for controlling the on-off of the radio frequency switch, adjusting the capacitance value and monitoring the probe output data.

2. The radio frequency matcher automatic detection apparatus of claim 1, wherein, The vacuum adjustable capacitor in the analog load module (20) has a capacitance value range of 0-200 pF, and the adjustment mode is a stepping motor, a relay or a voltage-controlled diode.

3. The radio frequency matcher automatic detection apparatus of claim 1, wherein, The control module (40) comprises a microcontroller and a capacitance adjustment element.

4. The radio frequency matcher automatic detection apparatus of claim 1, wherein, The capacitors of the analog load module (20) are interconnected through metal connecting strips, and the inductors are grounded.

5. The radio frequency matcher automatic detection apparatus of claim 1, wherein, The Load end of the radio frequency switch S3 is connected to the analog load module (20), and the Com end is connected to the absorption load module (30).

6. The radio frequency matcher automatic detection apparatus of claim 1, wherein, The control module (40) further comprises a storage module, an output module and a communication control for controlling the vacuum capacitor value module, the storage module is used for recording the capacitor configuration state, impedance data and probe output data, the output module comprises a local output module and a remote output module, and supports local visual Smith circle diagram and remote structured data output.

7. A method for automatic detection of a radio frequency match, applied to the device of any one of claims 1-6, characterized in that, The method comprises the following steps: Step S1, self-calibration: control the radio frequency switch S3 to switch to the Open port, detect the absorption load impedance offset and adjust the capacitor compensation; Step S2, matching range test: in the off state of the radio frequency power supply, the control module adjusts C3_DUT to 0%, and adjusts C1_DUT and C2_DUT to 0% and 100% respectively, and collects impedance data in four combinations; Step S3, matching time and stability test: adjust the simulated load impedance according to the preset curve in us level, simulate the ignition stage of the process chamber, and detect the standing wave ratio and output port data.

8. The method of claim 7, wherein, In the test, the voltage and current data of the output ports Port#1 and Port#2 are collected in real time through the second probe (104) and the third probe (105).

9. The method of claim 7, wherein, The simulated load impedance adjusted by the preset curve includes pre-ionization stage impedance Z1, breakdown stage impedance Z3 and steady state stage impedance Z4.

10. The method of claim 7, wherein, The threshold value of the standing wave ratio in the stability test is VSWR≤1.2.

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