TWI857796B - System for monitoring ionization rate of cleaning etching gas and method of using the system - Google Patents

Abstract

The present disclosure provides a system including a chamber, a pressure module, a flow module, and an analysis module. The chamber is used for entering a cleaning etching gas to etch a semiconductor film. The pressure module is used for measuring a pressure change curve of pressure changing with time in the chamber. The flow module is used for measuring a flow rate of the cleaning etching gas entering the chamber. The analysis module is used for calculating an ionization rate of the cleaning etching gas based on the pressure change curve, the flow rate, a system calibration value, a reference flow rate of the cleaning etching gas, and a reference pressure of the cleaning etching gas, in which the reference pressure is the pressure of the cleaning etching gas with the reference flow rate when the cleaning etching gas is not ionized.

Description

System for monitoring the dissociation rate of cleaning etching gas and method of using the same

The present disclosure relates to a system for monitoring the dissociation rate of a cleaning etch gas and a method of using the same.

The deposition process may be accompanied by a cleaning process to remove deposition residues in the chamber. However, due to factors such as the aging of process-related tools, the cleaning process may not be effectively implemented, and too much deposition residues may remain in the chamber, affecting the yield of the deposition process. When the efficiency of the cleaning process decreases, in order to ensure that the deposition residues are removed, the time of the cleaning process is often increased, resulting in process waste. Moreover, in order to confirm whether the deposition residues are removed, the operation of the machine may need to be stopped, thereby reducing the process efficiency. Therefore, a new system and a method of using the system are needed to effectively monitor the efficiency of the implementation of the cleaning process.

The present disclosure provides a system for monitoring the dissociation rate of a cleaning etching gas. The system includes a chamber, a pressure module, a flow module, and an analysis module. The chamber is used to introduce a cleaning etching gas to etch a semiconductor film. The pressure module is used to measure a pressure change curve of the pressure in the chamber changing with time. The flow module is used to measure the cleaning etching gas flow rate of the cleaning etching gas introduced into the chamber. The analysis module is used to calculate the dissociation rate of the cleaning etching gas according to the pressure variation curve, the cleaning etching gas flow rate, the system calibration value, the cleaning etching gas flow rate reference value and the cleaning etching gas pressure reference value, wherein the cleaning etching gas pressure reference value is the pressure value of the cleaning etching gas having the cleaning etching gas flow rate reference value when it is not dissociated.

In some embodiments, the analysis module is used to calculate the dissociation rate based on a first pressure at a first time in the pressure variation curve, a cleaning etching gas flow rate, a system calibration value, a cleaning etching gas flow rate baseline value, and a cleaning etching gas pressure baseline value, and the first time is the time at the highest point in the rising section of the pressure variation curve from the first platform to the second platform.

In some embodiments, the cavity is further used to pass an inert gas; the flow module is further used to measure the inert gas flow of the inert gas passed into the cavity; the analysis module is further used to calculate the system correction value according to the pressure variation curve, the inert gas flow, the inert gas flow reference value and the inert gas pressure reference value; and the inert gas pressure reference value is the pressure value of the inert gas having the inert gas flow reference value.

In some embodiments, the analysis module is used to calculate the system correction value according to the second pressure, the inert gas flow rate, the inert gas flow rate baseline value and the inert gas pressure baseline value at the second time in the pressure variation curve, and the second time is after the inert gas is introduced into the chamber and approximately when the cleaning etching gas is introduced into the chamber.

In some embodiments, the system further includes a recording module and a display module. The recording module is used to record a plurality of dissociation rates obtained by repeatedly using the analysis module, and record these dissociation rates into a dissociation rate variation curve according to the corresponding plurality of repetition times. The display module is used to display the dissociation rate variation curve and display a notification when the dissociation rate variation curve includes a dissociation rate lower than a value.

The present disclosure also provides a method for using a system for monitoring the dissociation rate of a cleaning etch gas. The method includes the following operations. A cleaning etch gas is introduced into a chamber to etch a first semiconductor film in the chamber. A pressure module is used to measure a first pressure change curve of the pressure in the chamber changing with time. A flow module is used to measure a first cleaning etch gas flow rate of the cleaning etch gas introduced into the chamber. An analysis module is used to calculate a first dissociation rate of the cleaning etch gas according to a first pressure variation curve, a first cleaning etch gas flow rate, a system calibration value, a cleaning etch gas flow rate reference value, and a cleaning etch gas pressure reference value, wherein the cleaning etch gas pressure reference value is a pressure value of the cleaning etch gas having the cleaning etch gas flow rate reference value when not dissociated.

In some embodiments, the clean etch gas includes a fluorine-containing gas.

In some embodiments, etching the first semiconductor film includes an etching process and an over-etching process; the first pressure variation curve has a rising section from a first platform corresponding to the etching process to a second platform corresponding to the over-etching process; and using an analysis module includes calculating a first dissociation rate based on the pressure at the highest point of the rising section, a first cleaning etching gas flow rate, a system calibration value, a cleaning etching gas flow rate baseline value, and a cleaning etching gas pressure baseline value.

In some embodiments, the method further includes: introducing an inert gas into the cavity; using a flow module to measure the inert gas flow rate of the inert gas introduced into the cavity; and using an analysis module to calculate a system correction value based on a first pressure variation curve, an inert gas flow rate, an inert gas flow rate benchmark value, and an inert gas pressure benchmark value, wherein the inert gas pressure benchmark value is a pressure value of an inert gas having an inert gas flow rate benchmark value.

In some embodiments, the inert gas is introduced before the cleaning etching gas is introduced; and the analysis module is used to calculate the system correction value according to a pressure corresponding to the introduction of the cleaning etching gas in the first pressure variation curve, the inert gas flow rate, the inert gas flow rate baseline value and the inert gas pressure baseline value.

In some embodiments, the method further includes the following operations. Removing the cleaning etch gas from the chamber. Introducing the cleaning etch gas into the chamber to etch a second semiconductor film in the chamber. Using a pressure module to measure a second pressure variation curve in which the pressure in the chamber varies with time. Using a flow module to measure a second cleaning etch gas flow of the cleaning etch gas introduced into the chamber. Using an analysis module to calculate a second dissociation rate of the cleaning etch gas based on the second pressure variation curve, the second cleaning etch gas flow, the system calibration value, the cleaning etch gas flow reference value, and the cleaning etch gas pressure reference value. A recording module is used to record a first dissociation rate corresponding to a first monitoring time and a second dissociation rate corresponding to a second monitoring time, and the second monitoring time is after the first monitoring time.

In order to make the description of the present disclosure more detailed and complete, the following is an illustrative description of the implementation mode and specific implementation mode. This does not limit the implementation mode of the present disclosure to a single form. The implementation modes of the present disclosure can be combined and/or replaced with each other in beneficial situations, and other implementation modes can be added without further description.

The terms "about", "approximately", "close to", "substantially" or "substantially" in the present disclosure include the numerical values and features and the deviation ranges of the numerical values and features that can be understood by those of ordinary skill in the art. For example, taking into account the errors of the numerical values and features, these terms may represent values within one or more standard deviations of the numerical values (e.g., values within ±30%, ±20%, ±15%, ±10% or ±5%), or represent the deviations covered by the features in practical operations (e.g., the statement "substantially parallel" may mean close to parallel in practice rather than perfect parallel in ideal). In addition, the acceptable deviation range may be selected according to the measured properties or other properties, rather than applying one deviation range to all numerical values and features.

The present disclosure provides a system for monitoring the dissociation rate of a cleaning etching gas. The system includes a chamber, a pressure module, a flow module, and an analysis module. The chamber is used to introduce a cleaning etching gas to etch a semiconductor film. The pressure module is used to measure a pressure change curve of the pressure in the chamber changing with time. The flow module is used to measure the cleaning etching gas flow rate of the cleaning etching gas introduced into the chamber. The analysis module is used to calculate the dissociation rate of the cleaning etch gas according to the pressure variation curve, the cleaning etch gas flow rate, the system calibration value, the cleaning etch gas flow rate baseline value and the cleaning etch gas pressure baseline value, wherein the cleaning etch gas pressure baseline value is the pressure value of the cleaning etch gas with the cleaning etch gas flow rate baseline value when it is not dissociated (or substantially electrically neutral). The system disclosed in the present invention can effectively monitor the implementation efficiency of the cleaning process by monitoring the dissociation rate of the cleaning etch gas, and thus adjust the implementation time of the cleaning process in real time to effectively avoid stopping the machine operation to detect the implementation efficiency of the cleaning process. In other words, the system disclosed in the present invention effectively avoids process waste, increases process yield and efficiency, and significantly reduces process costs. Next, the system of the present disclosure is described in detail according to some implementation methods.

Refer to the schematic diagram of FIG. 1. The system 10 of the present disclosure includes a chamber 100, a pressure module 200, a flow module 300, and an analysis module 400. The chamber 100 is directly connected to the pressure module 200 and the flow module 300 to measure the pressure in the chamber 100 and the flow rate of the gas (e.g., the cleaning etching gas CEG and/or the inert gas IG described below) introduced into the chamber 100 through the pressure module 200 and the flow module 300, respectively. The pressure (and/or the pressure change curve of the pressure change with time) and the flow rate obtained by the pressure module 200 and the flow module 300 are then used by the analysis module 400 to obtain the dissociation rate of the cleaning etching gas CEG when performing the cleaning process in the chamber 100. Next, each component is introduced in detail.

First, the chamber 100 is described with reference to FIG. 2 . The chamber 100 can be used to perform any feasible deposition process, such as chemical vapor deposition, physical vapor deposition, etc., and after the deposition process is completed, there may be deposition residues in the chamber 100 (i.e., the semiconductor film 101 shown in FIG. 2 in the present disclosure, but the actual position, size, shape, etc. of the semiconductor film 101 in the chamber 100 is not limited). The deposition precursor (not shown) of the deposition process can enter the chamber 100 through the inlet 102 of the chamber 100 . The chamber 100 is also used to introduce a cleaning etching gas CEG into the chamber 100 through an inlet 102 of the chamber 100 (in the figure, the introduction is indicated by an arrow pointing to the chamber) to perform an etching-related cleaning process on the semiconductor film 101 formed by the deposition process to remove the deposited residues. In some embodiments, the cleaning etching gas CEG includes an ionized cleaning etching gas CEG. In some embodiments, the chamber 100 is a vacuum chamber, and the pressure in the chamber 100 is less than the atmospheric pressure.

Continue to refer to Fig. 2. In some embodiments, the system 10 further includes a radio frequency signal generator RF that can be directly and/or indirectly connected to the chamber 100, so that the radio frequency signal generator RF ionizes the cleaning etching gas CEG into the cleaning etching gas CEG including ions by providing radio frequency. In some embodiments, the radio frequency signal generator RF includes a first radio frequency signal generator RF1 and a second radio frequency signal generator RF2 to effectively increase the amount of ionized cleaning etching gas CEG, wherein the first radio frequency signal generator RF1 can first perform an ionization process on the cleaning etching gas CEG outside the chamber 100, and then the cleaning etching gas CEG ionized by the first radio frequency signal generator RF1 can be introduced into the chamber 100 and then subjected to another ionization process by the radio frequency provided by the second radio frequency signal generator RF2. In some embodiments, the system 10 further includes a remote chamber RC between the first RF signal generator RF1 and the chamber 100 and connected to the first RF signal generator RF1 and the chamber 100, so that the cleaning etching gas CEG can be ionized by the RF provided by the first RF signal generator RF1 in the remote chamber RC before entering the chamber 100. In some embodiments, the second RF signal generator RF2 can also be used for plasma-related deposition processes (such as plasma enhanced chemical vapor deposition, etc.). In some embodiments, the RF frequencies of the first RF signal generator RF1 and the second RF signal generator RF2 are independently 10 MHz to 15 MHz, such as 13.56 MHz, etc.

The chamber 100 is described below with reference to FIG. 2. In some embodiments, the chamber 100 includes an electrode 103 to facilitate the ionization of the cleaning etching gas CEG (and/or the deposition precursor when performing the deposition process). In some embodiments, the electrode 103 includes a first electrode 104 and a second electrode 105 below the first electrode 104, and the deposition film formed by the deposition process can be located on the second electrode 105 and between the first electrode 104 and the second electrode 105. In some embodiments, the first electrode 104 includes a plurality of gas channels 104A arranged adjacent to each other and facing the second electrode 105, so as to facilitate the cleaning etching gas CEG entering from the inlet 102 and/or the deposition precursor during the deposition process to be evenly dispersed in the chamber 100 under the influence of the distribution of the gas channels 104A when flowing through the gas channels 104A, thereby facilitating the improvement of the deposition uniformity of the deposition process and the etching uniformity in the cleaning process. In other words, the first electrode 104 can also be referred to as a diffusion plate. In some embodiments, the second electrode 105 can also be heated and referred to as a heating plate to facilitate the implementation of the deposition process.

The chamber 100 is described below with reference to FIG. 2 . In some embodiments, the chamber 100 further includes a back plate 106 above the first electrode 104. The back plate 106 can fix the first electrode 104, and a space 106A is provided between the back plate 106 and the first electrode 104 to facilitate the cleaning etching gas CEG (and/or deposition precursor when performing a deposition process) entering from the inlet 102 to diffuse in the space 106A to the first electrode 104. In some embodiments, the chamber 100 further includes an outlet 107 to connect to an exhaust pump (not shown) outside the chamber 100. In some embodiments, the chamber 100 further includes a fixing member 108 to fix any feasible substrate (not shown, such as a glass substrate, a semiconductor board, etc.) on the second electrode 105, so that the deposition film formed in the deposition process can be deposited on the substrate. In some embodiments, the chamber 100 further includes a supporting column 110 to support the second electrode 105, and the second electrode 105 and the substrate thereon can be moved by lifting the supporting column 110 to facilitate the deposition process.

Next, the pressure module 200 of FIG. 1 is described. The pressure module 200 includes any feasible pressure gauge (not shown) directly connected to the chamber 100 to measure the pressure change in the chamber 100 when the cleaning process is performed. In some embodiments, the pressure gauge includes a capacitive vacuum gauge, a pressure sensor, a Pyranny vacuum gauge, a Baden tube pressure gauge, a hot filament electrode ion vacuum gauge, a U-type pressure gauge, the like, or a combination thereof. In some embodiments, the pressure module 200 further includes any feasible pressure gauge controller (not shown) to read, display, calibrate, and transmit the pressure value measured by the pressure gauge. In some embodiments, the pressure module 200 further includes any feasible computer device (not shown, such as a computer, etc.) with a processor, a memory, etc., to convert the pressure value into a pressure variation curve of pressure variation with time (such as referring to the pressure variation curve PC in FIG. 4 ) according to the pressure gauge measurement time, and can access the pressure variation curve, etc. In some embodiments, the connection between the pressure gauge, the pressure gauge controller and/or the computer device may include any feasible wired and/or wireless connection, such as a connection based on a universal interface bus, a universal serial bus, a recommended standard-232, a video graphics array, an Ethernet, a local area network, the like, or a combination thereof. In some embodiments, the pressure module 200 further includes any feasible pressure valve (not shown), such as a throttling valve, an isolation valve, a gate valve, a flow control valve, the like, or a combination thereof, to provide pressure regulation at the connection of the components as required.

Next, the flow module 300 of FIG. 1 is described. The flow module 300 includes any feasible flow meter (not shown) directly connected to the chamber 100 to measure the flow rate of the cleaning etching gas CEG (and/or the inert gas IG described below) introduced into the chamber 100 when performing the cleaning process. In some embodiments, the flow meter includes a flow meter based on thermal sensing, pressure sensing, or a combination thereof. In some embodiments, the flow module 300 further includes any feasible flow meter controller (not shown) to read, display, calibrate, and transmit the flow value measured by the flow meter. In some embodiments, the flow module 300 further includes any feasible computer device (not shown, such as a computer, etc.) with a processor, memory, etc., and can share the same computer device with the pressure module 200 to access the flow value, etc. In some embodiments, the connection between the flow meter, the flow meter controller and/or the computer device may include any feasible wired and/or wireless connection, such as a connection based on a universal interface bus, a universal serial bus, a recommended standard-232, a video graphics array, an Ethernet, a local area network, the like, or a combination thereof. In some embodiments, the flow module 300 further includes any feasible flow valve (not shown), such as a throttling valve, a flow control valve, the like, or a combination thereof, to provide flow regulation at the connection of the components as required.

Next, the analysis module 400 of FIG. 1 is described. The analysis module 400 is used to calculate the dissociation rate of the cleaning etch gas CEG when performing the cleaning process according to the pressure variation curve obtained by the pressure module 200, the cleaning etch gas flow obtained by the flow module 300, the system calibration value, the cleaning etch gas flow reference value, and the cleaning etch gas pressure reference value. In some embodiments, the analysis module 400 includes any feasible computer device with a processor, memory, etc. (not shown, such as a computer, etc.), and can share the same computer device with the pressure module 200 and/or the flow module 300 to perform the above-mentioned calculation to obtain the dissociation rate, and can access the dissociation rate, etc. The system calibration value is a calibration value for adjusting the dissociation rate calculated by the analysis module 400 in response to various system and/or human errors when the system performs the cleaning process, and the system calibration value can be obtained according to any feasible method, wherein a preferred system calibration value provided by the present disclosure is described in detail below. The cleaning etching gas pressure baseline value is a pressure value of the cleaning etching gas CEG in the chamber 100 when the cleaning etching gas CEG is introduced into the chamber 100 at a cleaning etching gas flow baseline value and the cleaning etching gas CEG is not dissociated (for example, at least 95%, at least 99% or even 100% of the cleaning etching gas CEG is not dissociated, and for example, the ionization of the cleaning etching gas CEG is avoided by not starting the radio frequency signal generator RF). Therefore, the measured pressure variation curve and cleaning etching gas flow rate are compared with the undissociated cleaning etching gas pressure reference value and cleaning etching gas flow reference value by the analysis module 400, and then calibrated with the system calibration value to obtain the accurate dissociation rate of the present disclosure. The cleaning etching gas flow reference value and its corresponding cleaning etching gas pressure reference value can be selected according to the needs. In some embodiments, a preferred cleaning etch gas flow rate reference value is 8000 sccm to 14000 sccm, such as 8000 sccm, 9000 sccm, 10000 sccm, 11000 sccm, 12000 sccm, 13000 sccm or 14000 sccm, etc.; a preferred cleaning etch gas pressure reference value is 280 mtorr to 340 mtorr, such as 280 mtorr, 290 mtorr, 300 mtorr, 310 mtorr, 320 mtorr, 330 mtorr or 340 mtorr, etc.; for example, when the flow rate of the cleaning etch gas CEG introduced into the chamber 100 is 11000 sccm, the corresponding cleaning etch gas CEG pressure is 310 mtorr. mtorr. In some embodiments, the cleaning etch gas flow rate may be the same as or different from the cleaning etch gas flow rate benchmark value. In some embodiments, the analysis module 400 further includes any feasible data storage device (not shown, such as a portable hard drive, a cloud database, etc.) to access the system calibration value, the cleaning etch gas flow rate benchmark value, the cleaning etch gas pressure benchmark value, the pressure variation curve, the cleaning etch gas flow rate, the dissociation rate (and/or the inert gas flow rate, the inert gas flow rate benchmark value and the inert gas pressure benchmark value described below), etc. In some embodiments, the connection between the computer device and the data storage device may include any feasible wired and/or wireless connection, such as a connection based on USB, Bluetooth, Ethernet, local area network, wide area network, the like, or a combination thereof.

The analysis module 400 of FIG. 1 is described in detail. In some embodiments, the analysis module 400 is used to convert the first pressure P1 at the first time, the cleaning etching gas flow rate F _CEG , the system correction value C, the cleaning etching gas flow rate reference value F _CEG,S and the cleaning etching gas pressure reference value P _CEG,S in the pressure variation curve into the dissociation rate IR, as shown in the following formula (1) and formula (2): Formula (1), Formula (2), wherein P0 is the pressure value that the cleaning etch gas _CEG with the cleaning etch gas flow rate F CEG should have when not dissociated after being corrected by the system correction value C and compared with the known cleaning etch gas flow rate reference value F _CEG ,S and its corresponding cleaning etch gas pressure reference value P _CEG,S . Therefore, by comparing this pressure value P0 with the measured first pressure P1, an accurate dissociation rate IR of the cleaning etch gas CEG can be obtained. The first pressure P1 is taken from the first time in the pressure variation curve (for example, refer to the first time T1 in Figure 4), and the first time is the time at the highest point in the rising section of the pressure variation curve from the first platform to the second platform (for example, refer to the first platform PF1, the second platform PF2, the rising section IS and the highest point HP in Figure 4). Since the cleaning process is performed based on the cleaning etching gas CEG etching the semiconductor film 101 to remove the deposited residues, the cleaning process may include an etching process before etching the semiconductor film 101 and an over-etching process after the etching process, that is, the first platform and the second platform correspond to the etching process and the over-etching process respectively, and the first pressure accurately reflects the system state that affects the dissociation rate. In some embodiments, the first platform and the second platform occur after the cleaning etching gas CEG has been introduced into the chamber 100. In some embodiments, the first platform and the second platform occur after the radio frequency signal generator RF has been activated to ionize the cleaning etching gas CEG. In some embodiments, the first pressure P1 is a pressure value having a maximum value in the pressure variation curve (not shown in the figure).

The system calibration value is described in detail with reference to FIG. 1 and FIG. 2. In some embodiments, a more accurate system calibration value can be obtained by introducing an inert gas IG into the chamber 100. In detail, the chamber 100 further includes a module for introducing an inert gas IG before introducing the cleaning etching gas CEG, wherein the inert gas IG can enter the chamber 100 through the inlet 102; once the inert gas IG is introduced into the chamber 100, the pressure module 200 can be used to measure the pressure change in the chamber 100, and thus obtain a pressure change curve; the flow module 300 can also further include a module for measuring the inert gas flow rate of the inert gas IG introduced into the chamber 100; and the analysis module 400 can also further include a module for calculating a system calibration value based on the pressure change curve, the inert gas flow rate, the inert gas flow rate reference value and the inert gas pressure reference value. The inert gas pressure reference value is a pressure value of the inert gas IG in the chamber 100 when the inert gas IG is introduced into the chamber 100 at an inert gas flow reference value and the chamber 100 substantially does not include the cleaning etching gas CEG (for example, before or when the cleaning etching gas CEG is introduced). Therefore, the measured pressure variation curve and the inert gas flow rate are compared with the inert gas pressure reference value and the inert gas flow reference value by the analysis module 400 to obtain the accurate system correction value of the present disclosure, so as to accurately correct errors such as those based on the exhaust pump, pressure valve, flow valve, human operation, etc. The inert gas flow reference value as a reference and its corresponding inert gas pressure reference value can be selected according to the needs. In some embodiments, a preferred inert gas flow rate reference value is 2000 sccm to 8000 sccm, such as 2000 sccm, 3000 sccm, 4000 sccm, 5000 sccm, 6000 sccm, 7000 sccm or 8000 sccm, etc.; a preferred inert gas pressure reference value is 131 mtorr to 191 mtorr, such as 131 mtorr, 141 mtorr, 151 mtorr, 161 mtorr, 171 mtorr, 181 mtorr or 191 mtorr, etc.; for example, when the flow rate of the inert gas IG introduced into the chamber 100 is 5000 sccm, the corresponding inert gas IG pressure is 161 mtorr. In some embodiments, the inert gas flow rate may be the same as or different from the inert gas flow rate reference value. In some embodiments, in addition to the chamber 100 further including a passage for the inert gas IG to obtain an accurate system calibration value, the passage of the inert gas IG also helps to make the cleaning etching gas CEG introduced later to be ionized more easily to improve the dissociation rate. For example, the inert gas IG may also flow through the remote chamber RC together with the cleaning etching gas CEG and assist the ionization process of the cleaning etching gas CEG in the remote chamber RC.

The system correction value is further described with reference to FIG. 1 and FIG. 2. In some embodiments, the analysis module 400 is used to convert the second pressure P2 at the second time in the pressure variation curve, the inert gas flow rate F _IG , the inert gas flow rate reference value F _IG,S and the inert gas pressure reference value P _IG,S into a system correction value C applicable to the above formula (1) and formula (2), as shown in the following formula (3): Formula (3). Formula (3) compares the measured second pressure P2 and the inert gas flow rate F _IG with the known inert gas flow rate reference value F _IG,S and its corresponding inert gas pressure reference value P _IG,S to obtain an accurate system calibration value C. The second pressure P2 is taken from the second time in the pressure variation curve (for example, refer to the second time T2 in FIG. 4), and the second time is after the inert gas IG is introduced into the chamber 100 and at about the time when the cleaning etching gas CEG is introduced into the chamber 100, for example, substantially equal to the time when the cleaning etching gas CEG is introduced into the chamber 100, or for example, within 1 second before the cleaning etching gas CEG is introduced into the chamber 100, etc., to ensure that the accurate system calibration value C is obtained when the chamber 100 does not yet contain the cleaning etching gas CEG. In some implementations, the second time occurs before the first time described above.

In some embodiments, the system 10 further includes a recording module (not shown) for repeatedly recording a plurality of dissociation rates obtained by using the analysis module 400, and recording these dissociation rates as dissociation rate variation curves (e.g., refer to the dissociation rate variation curve IRC in FIG. 5 ) according to the corresponding plurality of repetition times (or time). In other words, each time a cleaning process is performed to remove deposited residues, not only the dissociation rate of that time can be monitored by the system 10 of the present disclosure, but also the variation of the dissociation rate can be obtained by the recording module, so that the operator can make appropriate responses to the efficiency of the implementation of the cleaning process. In some embodiments, the recording module includes any feasible computer device (not shown, such as a computer, etc.) with a processor, memory, etc., and can share the same computer device with the pressure module 200, the flow module 300, and/or the analysis module 400. In some embodiments, the recording module can be connected to the data storage device of the analysis module 400 to access the dissociation rate obtained by each execution of the cleaning process, and further obtain the dissociation rate change curve, and the connection between the recording module and the data storage device of the analysis module 400 can include any feasible wired and/or wireless connection, such as a connection based on a universal serial bus, Bluetooth, Ethernet, local area network, wide area network, the like, or a combination thereof.

In some embodiments, the system 10 further includes a prediction module (not shown) for converting the dissociation rate variation curve into a dissociation rate prediction curve (e.g., refer to the dissociation rate prediction curve IRPC in FIG. 5 ). The prediction module can perform the above conversion according to any feasible curve fitting method, such as a curve fitting method based on exponential, Gaussian, polynomial, the like, or a combination thereof. In other words, before each cleaning process is executed, the dissociation rate of the cleaning process can be predicted based on the dissociation rate variation curve obtained from the previous cleaning processes, so that the operator can make appropriate responses to the implementation efficiency of the cleaning process more immediately. In some embodiments, the accuracy of the prediction module in predicting the dissociation rate is more than 90%. In some embodiments, the prediction module includes any feasible computer device (not shown, such as a computer, etc.) with a processor, memory, etc., and can share the same computer device with the pressure module 200, the flow module 300, the analysis module 400, and/or the recording module. In some embodiments, the prediction module can be connected to the recording module to convert the dissociation rate variation curve into a dissociation rate prediction curve, and the connection between the prediction module and the recording module can include any feasible wired and/or wireless connection, such as a connection based on a universal serial bus, Bluetooth, Ethernet, local area network, wide area network, the like, or a combination thereof.

In some embodiments, the system 10 further includes a display module (not shown) for displaying a pressure variation curve obtained by the pressure module 200 for executing the cleaning process, a cleaning etching gas flow rate (and/or an inert gas flow rate) obtained by the flow module 300 for executing the cleaning process, a dissociation rate obtained by the analysis module 400 for executing the cleaning process, a dissociation rate variation curve including a dissociation rate for executing a previous cleaning process obtained by the recording module, and/or a dissociation rate prediction curve obtained by the prediction module, etc., so that the operator can make appropriate responses to the implementation efficiency of the cleaning process in real time. In some embodiments, the display module further includes a notification for displaying when the dissociation rate and/or the dissociation rate variation curve includes a dissociation rate lower than a warning value, so that the operator can make appropriate responses to the implementation efficiency of the cleaning process more immediately. In some embodiments, the warning value includes a first warning value and a second warning value (for example, refer to the first warning value WP1 and the second warning value WP2 of FIG. 5). In some embodiments, the first warning value is when the dissociation rate is 65% to 75%, for example, 70%, and the second warning value is when the dissociation rate is 60% to 70%, for example, 65%. Therefore, when the dissociation rate is lower than the first warning value, the display module can remind the operator that the cleaning process needs to be implemented for a longer time because the efficiency of the cleaning process is insufficient, and when the dissociation rate is lower than the second warning value, the display module can remind the operator that the base station operation needs to be stopped because the efficiency of the cleaning process is seriously insufficient. In some embodiments, the display module includes any feasible display screen. In some embodiments, the display module includes any feasible computer device with a processor, memory, etc. (not shown, such as a computer, etc.), and can share the same computer device with the pressure module 200, the flow module 300, the analysis module 400, the recording module and/or the prediction module. In some embodiments, the display module may be connected to the pressure module 200, the flow module 300, the analysis module 400, the recording module and/or the prediction module, and this connection includes any feasible wired and/or wireless connection, such as a connection based on a universal serial bus, Bluetooth, Ethernet, a local area network, a wide area network, the like, or a combination thereof.

The present disclosure also provides a method 20 for using the system 10 for monitoring the dissociation rate of a cleaning etch gas. The method 20 includes the following operations 21 to 24, and refers to the method flow chart of FIG. 3. Operation 21 includes introducing a cleaning etch gas CEG into a chamber 100 to etch a first semiconductor film in the chamber 100. Operation 22 includes using a pressure module 200 to measure a first pressure change curve of the pressure in the chamber 100 changing with time. Operation 23 includes using a flow module 300 to measure a first cleaning etch gas flow rate of the cleaning etch gas CEG introduced into the chamber 100. Operation 24 includes using the analysis module 400 to calculate a first dissociation rate of the cleaning etch gas according to the first pressure variation curve, the first cleaning etch gas flow rate, the system calibration value, the cleaning etch gas flow rate reference value, and the cleaning etch gas pressure reference value, wherein the cleaning etch gas pressure reference value is the pressure value of the cleaning etch gas having the cleaning etch gas flow rate reference value when not dissociated. The first semiconductor film, the first pressure variation curve, the first cleaning etch gas flow rate, and the first dissociation rate are respectively equivalent to the semiconductor film, the pressure variation curve, the cleaning etch gas flow rate, and the dissociation rate described above, and therefore, the details can be referred to above. Next, method 20 of the present disclosure is described in detail according to some implementation modes and with reference to FIGS. 1 to 2 .

In operation 21 of method 20, a cleaning etching gas CEG is introduced into the chamber 100 so that the first semiconductor film (or the semiconductor film 101) in the chamber 100 can be etched by the cleaning process to remove the deposited residues. The flow rate of the cleaning etching gas CEG introduced into the chamber 100 can be adjusted according to demand, and the flow rate value is measured by the flow module 300 in operation 23 and the dissociation rate is calculated by the analysis module 400 in operation 24. In some embodiments, the cleaning etching gas CEG introduced into the chamber 100 is continuously introduced until the cleaning process is completed, and the cleaning etching gas flow rate from the introduction of the cleaning etching gas CEG into the chamber 100 to the completion of the cleaning process is substantially maintained at a constant value. In some embodiments, the cleaning etching gas CEG includes a fluorine-containing gas, such as nitrogen trifluoride, sulfur hexafluoride, the like, or a combination thereof. In some embodiments, the first semiconductor film (or semiconductor film 101) is a silicon-containing semiconductor film, such as silicon nitride, amorphous silicon, the like, or a combination thereof. In some embodiments, the thickness of the first semiconductor film (or semiconductor film 101) may be 2500 nm to 4500 nm, such as 2500 nm, 3000 nm, 3500 nm, 4000 nm, or 4500 nm. In some embodiments, the method 20 further includes performing any feasible deposition process to form a deposition residue such as the first semiconductor film (or semiconductor film 101) before performing operation 21. In some embodiments, the method 20 further includes using (or starting) a first radio frequency signal generator RF1 to ionize the cleaning etching gas CEG outside the chamber 100 before the cleaning etching gas CEG is introduced into the chamber 100. In some embodiments, the method 20 further includes using (or starting) a second radio frequency signal generator RF2 to ionize the cleaning etching gas CEG inside the chamber 100 after the cleaning etching gas CEG is introduced into the chamber 100.

In operation 22 of method 20, a first pressure variation curve (e.g., refer to pressure variation curve PC in FIG. 4 ) in which the pressure in chamber 100 varies with time is measured using pressure module 200. Since etching the first semiconductor film includes an etching process and an over-etching process, the first pressure variation curve has a rising section from a first platform corresponding to the etching process to a second platform corresponding to the over-etching process, as described above in detail.

In operation 23 of method 20, a first cleaning etch gas flow rate of the cleaning etch gas CEG introduced into the chamber 100 is measured using a flow module 300. In some embodiments, the flow rate of the cleaning etch gas CEG introduced into the chamber 100 is measured by the flow module 300 to be 8000 sccm to 14000 sccm, for example, 8000 sccm, 9000 sccm, 10000 sccm, 11000 sccm, 12000 sccm, 13000 sccm, or 14000 sccm.

In operation 24 of method 20, an analysis module 400 is used to calculate a first dissociation rate according to the first pressure variation curve, the first cleaning etch gas flow rate, the system correction value, the cleaning etch gas flow rate reference value, and the cleaning etch gas pressure reference value. In some embodiments, the analysis module 400 is used to calculate the first dissociation rate according to the pressure at the highest point in the rising section of the first pressure variation curve (i.e., the first pressure described above), the first cleaning etch gas flow rate, the system correction value, the cleaning etch gas flow rate reference value, and the cleaning etch gas pressure reference value. The first pressure obtained by the pressure module 200 can reflect the implementation efficiency of the cleaning process, and is converted into an accurate first dissociation rate after correction and comparison as described in detail above, so that the operator can make appropriate responses according to the implementation efficiency of the cleaning process.

In some embodiments, the method 20 further includes introducing an inert gas IG into the chamber 100 before introducing the cleaning etching gas CEG into the chamber 100 to perform the above-described method of obtaining a system calibration value and increasing the number of ionizations of the cleaning etching gas CEG. The flow rate of the inert gas IG introduced into the chamber 100 can be adjusted as required, and the method 20 can further include measuring the inert gas flow rate of the inert gas IG introduced into the chamber 100 by the flow module 300. In some embodiments, the flow rate of the inert gas IG introduced into the chamber 100 is measured by the flow module 300 to be 2000 sccm to 8000 sccm, such as 2000 sccm, 3000 sccm, 4000 sccm, 5000 sccm, 6000 sccm, 7000 sccm or 8000 sccm, etc. In some embodiments, the flow ratio of the cleaning etching gas CEG to the inert gas IG introduced into the chamber 100 is 1 to 10, such as 1, 2, 4, 6, 8 or 10. In some embodiments, the inert gas IG includes argon fluorine, its analogs or a combination thereof. Since the chamber 100 also introduces the inert gas IG, the first pressure variation curve measured by the pressure module 200 may also include the change in pressure in response to the introduction of the inert gas IG. Therefore, in the embodiment in which the chamber 100 also introduces the inert gas IG, the method 20 may further include using the analysis module 400 to calculate the system calibration value according to the first pressure variation curve, the inert gas flow rate, the inert gas flow rate reference value and the inert gas pressure reference value. In some embodiments, the analysis module 400 is used to calculate the system correction value based on the pressure in the first pressure variation curve approximately corresponding to the pressure when the cleaning etching gas is introduced (i.e., the second pressure described above), the inert gas flow rate, the inert gas flow rate baseline value, and the inert gas pressure baseline value. In some embodiments, the inert gas IG is introduced into the chamber 100 before the RF signal generator RF is used (or activated) to ionize the cleaning etching gas CEG, and the inert gas IG is introduced into the chamber 100 until the first RF signal generator RF1 is used (or activated) to ionize the cleaning etching gas CEG, after the cleaning etching gas CEG is introduced into the chamber 100, and after the second RF signal generator RF2 is used (or activated) to ionize the cleaning etching gas CEG. Before cleaning the etching gas CEG, the inert gas IG is stopped from continuously entering the chamber 100 by closing the flow valve, for example, so that the inert gas IG helps the cleaning etching gas CEG to ionize, but avoids the cleaning etching gas CEG having the inert gas IG in the chamber 100 when etching the first semiconductor film (that is, when the first platform in the first pressure variation curve corresponding to the etching process occurs, the chamber 100 does not substantially include the inert gas). In some embodiments, the inert gas flow rate from the time the inert gas IG is introduced into the chamber 100 to the time the inert gas IG is finished entering the chamber 100 is substantially maintained at a constant value.

In some embodiments, the method 20 further includes repeating the above operations to perform another cleaning process and/or deposition process to monitor the dissociation rate change of the system. For example, the cleaning etch gas CEG that has undergone the above cleaning process is removed from the chamber 100. Then, the cleaning etch gas CEG is introduced into the chamber 100 again to etch a second semiconductor film that can be formed in the chamber 100 through another deposition process. Then, the pressure module 200 is used again to measure a second pressure change curve of the pressure in the chamber 100 changing with time, and the flow module 300 is used again to measure the second cleaning etch gas flow rate of the cleaning etch gas CEG introduced into the chamber 100. Then, the analysis module 400 is used again to calculate the second dissociation rate of the cleaning etching gas according to the second pressure variation curve, the second cleaning etching gas flow rate, the system calibration value, the cleaning etching gas flow rate reference value and the cleaning etching gas pressure reference value. The description of the second semiconductor film, the second pressure variation curve, the second cleaning etching gas flow rate and the second dissociation rate are similar to the description of the first semiconductor film, the first pressure variation curve, the first cleaning etching gas flow rate and the first dissociation rate in the above text, so the details can be referred to above. The repeated cleaning process can also include introducing an inert gas IG into the chamber 100 to obtain another system calibration value. In some embodiments, the method 20 further includes using a recording module of the system 10 to record a first dissociation rate corresponding to a first monitoring time when performing a first cleaning process and/or a deposition process and a second dissociation rate corresponding to a second monitoring time when performing a second cleaning process and/or a deposition process, i.e., obtaining a dissociation rate variation curve, and repeating the method 20 of the present disclosure can also obtain a dissociation rate variation curve IRC as shown in FIG. 5. In some embodiments, the method 20 further includes using a prediction module of the system 10 to convert the dissociation rate variation curve into a dissociation rate prediction curve (e.g., referring to the dissociation rate prediction curve IRPC in FIG. 5). In some embodiments, method 20 further includes using a display module of system 10 to display in real time a pressure variation curve, a cleaning etching gas flow rate (and/or an inert gas flow rate), a dissociation rate, a dissociation rate variation curve, and/or a dissociation rate prediction curve, etc., and timely receive a notification when the dissociation rate and/or the dissociation rate variation curve includes a dissociation rate below a warning value.

Next, the system 10 and method 20 of the present disclosure are described with reference to the detailed embodiments of Figures 4 and 5. It should be noted that the embodiments are provided to enable a person skilled in the art to better understand the present disclosure, and are not intended to limit the scope of the present disclosure.

In one embodiment, a cleaning etch gas CEG and an inert gas IG are introduced into the chamber 100 to perform a cleaning process on the semiconductor film in the chamber 100, wherein the cleaning etch gas flow rate of the cleaning etch gas CEG is measured by the flow module 300 to be 11000 sccm, and the inert gas flow rate of the inert gas IG is measured by the flow module 300 to be 5000 sccm. The pressure variation curve PC measured by the pressure module 200 is shown in FIG. 4 , wherein point A in the curve corresponds to the time and pressure of the inert gas IG entering the chamber 100; point B corresponds to the time and pressure of using (or starting) the first RF signal generator RF1; point C corresponds to the time and pressure of the cleaning etching gas CEG entering the chamber 100 (i.e., the second time and the second pressure of the present embodiment, so as to convert the second pressure into system calibration value, but the present disclosure may also use the pressure 1 second before point C as the second pressure); point D corresponds to the time and pressure of stopping the introduction of inert gas IG into the chamber 100; point E corresponds to the time and pressure of using (or starting) the second RF signal generator RF2; the first platform PF1 corresponds to the etching process; the second platform PF2 corresponds to the etching process; the time and pressure HP at the highest point of the rising section IS between the first platform PF1 and the second platform PF2 correspond to the first time and first pressure mentioned above, so as to convert the first pressure into the dissociation rate; and point F corresponds to the end of the cleaning etching, such as stopping the introduction of the cleaning etching gas CEG into the chamber 100, turning off the RF signal generator RF, etc. In this embodiment, the second pressure is 165 mtorr, and the inert gas flow rate reference value and its corresponding inert gas pressure reference value can be taken as 5000 sccm and 161 mtorr according to the data accessed by the data storage device of the analysis module 400. Therefore, the system calibration value of this embodiment can be calculated by the analysis module 400 according to the above formula (3) as approximately 0.9758. In this embodiment, the first pressure is 625 mtorr, and the cleaning etching gas flow rate reference value and its corresponding cleaning etching gas pressure reference value can be taken as 11000 sccm and 310 mtorr according to the data accessed by the data storage device of the analysis module 400. Therefore, the dissociation rate of this embodiment can be calculated as about 96.7% according to the above formula (1) and formula (2) by the analysis module 400. By repeating the cleaning process, the dissociation rate of each time can be obtained by the system as shown in FIG. 5, i.e., the dissociation rate variation curve IRC and the dissociation rate prediction curve IRPC.

The system disclosed herein and the method for using the same can effectively, quickly and simply monitor the efficiency of the cleaning process by monitoring the dissociation rate of the cleaning etching gas, wherein the dissociation rate accurately reflects the influence of the system state on the dissociation rate, so that the implementation time of the cleaning process can be adjusted in real time according to the system state. For example, the dissociation rate can reflect whether the components in the chamber (such as the first electrode, the back plate, etc.) are affected by excessive aging, and whether any component in the system (such as the exhaust pump, the pressure valve, the flow valve, etc.) has a significant error that affects the dissociation rate. In other words, the system disclosed herein and the method of using the system can effectively increase the yield, efficiency and reduce the cost of the cleaning process, and avoid the reduction in process efficiency caused by stopping the machine operation to detect the efficiency of the implementation of the cleaning process, and avoid the waste caused by inefficient use of excessive cleaning etching gas.

The present disclosure is described in considerable detail in some embodiments, but other embodiments may also be possible, and therefore the description of the embodiments contained in the present disclosure should not limit the scope and spirit of the attached patent applications. For those with ordinary knowledge in the relevant technical field, modifications and changes can be made to the present disclosure without departing from the scope and spirit of the present disclosure. As long as these modifications and changes fall within the scope and spirit of the attached patent applications, they are covered by the present disclosure.

10: System 20: Method 21: Operation 22: Operation 23: Operation 24: Operation 100: Chamber 200: Pressure module 300: Flow module 400: Analysis module 101: Semiconductor membrane 102: Inlet 103: Electrode 104: First electrode 104A: Gas channel 105: Second electrode 106: Back plate 106A: Space 107: Outlet 108: Fixing part 110: Support column A: Point B: Point C: Point CEG: Cleaning etching gas D: Point E: Point F: Point IG: Inert gas IRC: Dissociation rate change curve IRPC: Dissociation rate prediction curve IS: Ascending section HP: Highest point P1: First pressure P2: Second pressure PC: Pressure change curve PF1: First platform PF2: Second platform RC: Remote cavity RF: Radio frequency signal generator RF1: First radio frequency signal generator RF2: Second radio frequency signal generator T1: First time T2: Second time WP1: First warning value WP2: Second warning value

When reading the drawings accompanying the present disclosure, it is recommended to understand various aspects of the present disclosure from the detailed description below. It should be noted that various feature sizes may not be drawn to scale in accordance with standard industry practices. And for the sake of clarity of discussion, various feature sizes may be enlarged or reduced. In addition, in order to simplify the drawings, conventional structures and components will be shown in the drawings in a simple schematic manner. FIG. 1 is a schematic diagram of a system for monitoring the dissociation rate of a cleaning etch gas according to some embodiments of the present disclosure. FIG. 2 is a partial schematic diagram of a chamber containing a system for monitoring the dissociation rate of a cleaning etch gas according to some embodiments of the present disclosure. FIG. 3 is a flow chart of a method for using a system for monitoring the dissociation rate of a cleaning etch gas according to some embodiments of the present disclosure. FIG. 4 is a diagram showing a pressure variation curve in a chamber according to some embodiments of the present disclosure. FIG. 5 is a diagram showing a dissociation rate variation curve of a cleaning etching gas according to some embodiments of the present disclosure.

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

10: System

100: Cavity

200: Pressure module

300:Flow module

400:Analysis module

Claims (11)

A system for monitoring the dissociation rate of a cleaning etching gas comprises: a chamber for introducing a cleaning etching gas to etch a semiconductor film; a pressure module for measuring a pressure change curve of a pressure in the chamber changing with time; a flow module for measuring a cleaning etching gas flow rate of the cleaning etching gas introduced into the chamber; and An analysis module is used to calculate a dissociation rate of the cleaning etching gas according to the pressure variation curve, the cleaning etching gas flow rate, a system calibration value, a cleaning etching gas flow rate reference value, and a cleaning etching gas pressure reference value, wherein the cleaning etching gas pressure reference value is a pressure value of the cleaning etching gas having the cleaning etching gas flow rate reference value when not dissociated. A system as described in claim 1, wherein the analysis module is used to calculate the dissociation rate based on a first pressure at a first time in the pressure variation curve, the cleaning etching gas flow rate, the system calibration value, the cleaning etching gas flow rate baseline value and the cleaning etching gas pressure baseline value, and the first time is a time at a highest point in a rising section of the pressure variation curve from a first platform to a second platform. A system as described in claim 1, wherein the cavity is further used to pass an inert gas; the flow module is further used to measure an inert gas flow rate of the inert gas passed into the cavity; the analysis module is further used to calculate the system correction value based on the pressure variation curve, the inert gas flow rate, an inert gas flow rate benchmark value and an inert gas pressure benchmark value; and the inert gas pressure benchmark value is a pressure value of the inert gas having the inert gas flow rate benchmark value. A system as described in claim 3, wherein the analysis module is used to calculate the system correction value based on a second pressure at a second time in the pressure variation curve, the inert gas flow rate, the inert gas flow rate baseline value and the inert gas pressure baseline value, and the second time is after the inert gas is introduced into the chamber and approximately when the cleaning etching gas is introduced into the chamber. The system as described in claim 1 further includes: a recording module for recording a plurality of dissociation rates obtained by repeatedly using the analysis module, and recording the dissociation rates into a dissociation rate variation curve according to the corresponding plurality of repetition times; and a display module for displaying the dissociation rate variation curve and displaying a notification when the dissociation rate variation curve includes a dissociation rate lower than a value. A method for using a system for monitoring the dissociation rate of a cleaning etch gas, comprising: Introducing a cleaning etch gas into a chamber to etch a first semiconductor film in the chamber; Using a pressure module to measure a first pressure variation curve of a pressure in the chamber varying with time; Using a flow module to measure a first cleaning etch gas flow rate of the cleaning etch gas introduced into the chamber; and An analysis module is used to calculate a first dissociation rate of the cleaning etching gas according to the first pressure variation curve, the first cleaning etching gas flow rate, a system calibration value, a cleaning etching gas flow rate reference value, and a cleaning etching gas pressure reference value, wherein the cleaning etching gas pressure reference value is a pressure value of the cleaning etching gas having the cleaning etching gas flow rate reference value when not dissociated. The method of claim 6, wherein the cleaning etching gas comprises a fluorine-containing gas. A method as described in claim 6, wherein etching the first semiconductor film includes an etching process and an over-etching process; the first pressure variation curve has a rising section from a first platform corresponding to the etching process to a second platform corresponding to the over-etching process; and using the analysis module includes calculating the first dissociation rate based on a pressure at a highest point of the rising section, the first cleaning etching gas flow rate, the system correction value, the cleaning etching gas flow rate baseline value and the cleaning etching gas pressure baseline value. The method as described in claim 6 further includes introducing an inert gas into the cavity; using the flow module to measure an inert gas flow rate of the inert gas introduced into the cavity; and using the analysis module to calculate the system correction value based on the first pressure variation curve, the inert gas flow rate, an inert gas flow rate benchmark value and an inert gas pressure benchmark value, wherein the inert gas pressure benchmark value is a pressure value of the inert gas having the inert gas flow rate benchmark value. A method as described in claim 9, wherein the introduction of the inert gas is performed before the introduction of the cleaning etching gas; and using the analysis module includes calculating the system correction value based on a pressure in the first pressure variation curve corresponding to the introduction of the cleaning etching gas, the inert gas flow rate, an inert gas flow rate baseline value and an inert gas pressure baseline value. The method as described in claim 6 further includes: Removing the cleaning etch gas from the chamber; Passing the cleaning etch gas into the chamber to etch a second semiconductor film in the chamber; Using the pressure module to measure a second pressure variation curve of a pressure in the chamber varying with time; Using the flow module to measure a second cleaning etch gas flow of the cleaning etch gas passed into the chamber; Using the analysis module to calculate a second dissociation rate of the cleaning etch gas based on the second pressure variation curve, the second cleaning etch gas flow, a system calibration value, the cleaning etch gas flow reference value and the cleaning etch gas pressure reference value; and A recording module is used to record the first dissociation rate corresponding to a first monitoring time and the second dissociation rate corresponding to a second monitoring time, and the second monitoring time is after the first monitoring time.

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