Etching end point detection method and system for plasma-free etching process

Abstract

The invention discloses an etching end point detection method and an etching end point detection system for a plasma-free etching process. The etching end point detection method comprises the following steps: acquiring a gas concentration signal; processing the gas concentration signal, establishing a signal change rate r (t) of the characteristic gas at the moment t, and taking the signal change rate r (t) as comparison data T; setting a standard value A, and comparing the comparison data T with the standard value A; when T is greater than or equal to A, judging that the etching process does not reach the etching end point; and when T is less than A, judging that the etching process reaches the etching end point. The detection system comprises a semiconductor etching process chamber, a tail gas emission pipeline and a detection device, the tail gas discharge pipeline is communicated with the semiconductor etching process chamber to discharge products and byproducts in the semiconductor etching process chamber; the detection device is arranged on the tail gas emission pipeline to detect the concentration of the characteristic gas in real time. The problem that plasma-free etching equipment lacks real-time and high-precision end point detection capability is solved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor inspection technology, and in particular to a method and system for detecting the etching endpoint in a plasma-free etching process. Background Technology

[0002] In plasma-free etching processes (such as vapor phase chemical etching and remote plasma etching), no plasma is generated in the main process chamber, and the traditional optical emission spectroscopy (OES) endpoint detection method is completely ineffective.

[0003] Existing technologies mostly employ etching schemes based on fixed time, which have significant drawbacks. For example, they cannot detect the etching progress in real time, which can easily lead to insufficient etching (residue) or over-etching (damage to the underlying material), affecting product yield. At the same time, the etching rate is affected by multiple factors such as temperature, pressure, and gas flow rate, and the fixed time method cannot adapt to process fluctuations. In addition, for wafers with multilayer film structures (such as polycrystalline silicon / silicon dioxide), the fixed time method cannot accurately determine the interlayer transition point.

[0004] Therefore, it is necessary to provide a new method and system for detecting etching endpoints in plasma-free etching processes to solve the aforementioned problems in the prior art. Summary of the Invention

[0005] The technical problem to be solved by this application is how to provide an etching endpoint detection method and system that can solve the problem of lack of real-time, high-precision endpoint detection capability in plasma-free etching equipment and be used in plasma-free etching processes.

[0006] To address the aforementioned technical problems, according to embodiments of this application, an etching endpoint detection method for a plasma-free etching process is provided, wherein the etching process does not generate plasma within the semiconductor etching process chamber, and the etching endpoint detection method includes: A detection device is installed on the exhaust gas pipeline of the semiconductor etching process chamber; The detection device is activated to detect the gas concentration of the characteristic gas in the exhaust pipe in real time and obtain the gas concentration signal. The gas concentration signal is processed to establish the signal change rate r(t) of the characteristic gas at time t, and the signal change rate r(t) is used as the comparison data T. Set a standard value A, and compare the comparison data T with the standard value A; When T≥A, it is determined that the etching process has not reached the etching endpoint; When T < A, the etching process is considered to have reached the etching endpoint.

[0007] According to an embodiment of this application, the signal change rate r(t) of the characteristic gas established at time t includes,

[0008] in, Let be the concentration value of the characteristic gas at time t; The characteristic gas concentration sampling period.

[0009] According to an embodiment of this application, the process of processing the gas concentration signal to establish the signal change rate r(t) of the characteristic gas at time t, and using the signal change rate r(t) as comparison data T, includes: The comparison data T is processed to reduce the impact of noise from single-point mutations on the comparison data T.

[0010] According to embodiments of this application, the comparison data T is processed to reduce the impact of noise from single-point mutations on the comparison data T, including: Select This is to reduce the impact of noise from single-point mutations on the comparative data T.

[0011] According to embodiments of this application, the comparison data T is processed to reduce the impact of noise from single-point mutations on the comparison data T, including: Calculate the moving average of the rate of change of the signal r(t) at time t. , as the comparison data T;

[0012] Where N is the number of sampling points participating in the averaging; i is the index variable; The sampling period for the characteristic gas concentration; Let be the instantaneous rate of change of the historical times of the i sampling points before time t.

[0013] According to an embodiment of this application, determining that the etching process has reached the etching endpoint when T < A includes: Subtract the moving average from the already determined time t. The algorithm delay is used to obtain the actual time when the etching process reaches the etching endpoint. ,

[0014] in, To calculate the moving average The inherent delay introduced by time; The time was set to prevent misjudgment.

[0015] According to embodiments of this application, the etching process is vapor phase chemical etching or remote plasma etching.

[0016] According to an embodiment of this application, the characteristic gas is a corrosive gas.

[0017] According to an embodiment of this application, the corrosive gas is , , , , , or One of them.

[0018] A detection system is provided for implementing the above-described etching endpoint detection method; the detection system includes a semiconductor etching process chamber, an exhaust gas emission pipeline, and a detection device. The exhaust gas pipeline is connected to the semiconductor etching process chamber to discharge the products and by-products inside the semiconductor etching process chamber. The detection device is installed in the exhaust gas pipeline to detect the concentration of characteristic gases in real time.

[0019] By employing the above technical solutions, in vapor phase chemical etching or remote plasma etching, the reactant gas undergoes a purely chemical reaction with the wafer surface to generate a single volatile product, such as... The product instantly detaches from the surface and enters the exhaust gas pipeline along with the carrier gas. The detection device is installed in the straight section of the pipeline, using FTIR, TDLAS, or other techniques to integrate the characteristic absorption peak spectrum, while simultaneously sampling the characteristic gas concentration periodically. The transport time of the covered gas from the chamber to the detection device is ≥2 seconds. The sampling period for different characteristic gas concentrations can be adjusted according to the different settings of the detection device. This invention achieves synchronization between reaction and detection time. Comparison data T is calculated based on the characteristic gas concentration signal and compared with the standard value A to determine whether the etching process has reached its endpoint. Furthermore, by processing the signal change rate r(t), the accuracy of the judgment can be improved, reducing the possibility of inaccurate endpoint determination caused by single-point noise mutations. This invention provides real-time endpoint detection capability based on the chemical reaction nature of plasma-free etching processes. Specifically, by detecting the change rate r(t) of the characteristic gas concentration signal, it can sensitively capture abrupt changes at the etching interface, offering greater resistance to baseline drift and more accurate judgment than absolute value detection. Moreover, the detection process only requires adding a mature gas concentration meter to the existing equipment's exhaust gas pipeline and upgrading the control system software, resulting in low modification costs. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the steps of an etching endpoint detection method for a plasma-free etching process according to an embodiment of the present invention. Figure 2The characteristic gas of the embodiments of the present invention ( The concentration curve of the gas is shown in the figure; where the horizontal axis X represents the reaction time in seconds and the vertical axis Y represents the gas concentration in pmm. Figure 3 The characteristic gas of the embodiments of the present invention ( The graph shows the rate of change of the concentration signal r(t); where the horizontal axis X is the reaction time in seconds and the vertical axis Y is the rate of change in pmm / s. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, 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. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0022] The following is combined Figures 1-3 The specific embodiments of the present invention will be further described in detail below.

[0023] Embodiments of the present invention provide a method for detecting the etching endpoint in a plasma-free etching process. The plasma-free etching process does not introduce plasma during etching and includes vapor-phase chemical etching. These processes rely entirely on high temperatures or the chemical reactivity of the gas itself to drive the reaction, without introducing plasma, thus avoiding physical damage to the device caused by high-energy particles. For example, HF gas etching is used. When catalyzed by anhydrous ethanol, the entire reaction process is in a gaseous state, effectively avoiding the adhesion effect of micro / nano structures due to liquid surface tension during release; that is, the etching process does not generate plasma in the semiconductor etching chamber, and the detection methods include: S1. Install a detection device on the exhaust gas pipeline of the semiconductor etching process chamber; S2. Start the detection device to detect the gas concentration of characteristic gases in the exhaust pipe in real time and obtain the gas concentration signal. S3. Process the gas concentration signal and establish the signal change rate r(t) of the characteristic gas at time t. Use the signal change rate r(t) as the comparison data T. S4. Set a standard value A, and compare the comparison data T with the standard value A; S5. When T≥A, it is determined that the etching process has not reached the etching endpoint; When T < A, the etching process is considered to have reached the etching endpoint.

[0024] In some embodiments, the detection device is located inside the exhaust gas duct of the semiconductor etching process chamber, so that the gas passing through the exhaust gas duct can pass through the detection device simultaneously, thereby facilitating the detection of the gas passing through the exhaust gas duct.

[0025] In some specific embodiments, the detection device may employ one of the following during the detection process: FTIR (Fourier Transform Infrared Spectroscopy), TDLAS (Tunable Laser Absorption Spectroscopy), NDIR (Non-Dispersive Infrared Spectroscopy), or OES (Optical Emission Spectroscopy). No specific limitation is made here, and the corresponding detection method shall be selected according to the actual use requirements.

[0026] In some embodiments, the concentration of a characteristic gas passing through the exhaust pipe needs to be detected during the detection process; wherein, the characteristic gas is a byproduct generated after the reaction in the semiconductor etching process chamber, and it is a corrosive gas, which can be... , , , , , or One of these gases. These gases have characteristic absorption peaks in the infrared spectral region, facilitating real-time concentration detection using the aforementioned optical detection techniques; simultaneously, in vapor-phase chemical etching or remote plasma etching, changes in the concentration of these gases directly reflect the extent of the etching reaction; when etching reaches its endpoint, i.e., when the etched layer is completely removed, the generation rate of these characteristic gases will significantly decrease, and their concentrations will tend to stabilize or decrease, thus making it easy to determine whether the etching endpoint has been reached based on changes in the concentration of characteristic gases. For example, with The target etching layer is Si, with Si as the substrate layer, using As a process gas in the etching reaction, the reaction during etching, i.e., when etching the target etched layer, is as follows:

[0027] The reaction during substrate etching is as follows:

[0028] During the etching process, only the target etching layer is etched, meaning the substrate layer is not etched. However, etching of both the target etching layer and the substrate layer produces... Therefore, through detection The concentration can be used to determine the current etching position, and thus whether the etching is complete.

[0029] In some embodiments, after acquiring the gas concentration signal, it is necessary to process the gas concentration signal to obtain comparative data T. Specifically, since the absolute value of the gas concentration signal is affected by multiple factors such as gas flow rate, chamber pressure, temperature fluctuation, and pipeline adsorption / desorption, it cannot stably reflect the etching progress. Therefore, it must be converted into comparative data T for accurate comparison. That is, the essence of T is to convert the original sensor signal into a process control parameter with clear physical meaning and high signal-to-noise ratio. More specifically, the comparative data T is the signal change rate r(t) of the characteristic gas, which will be described in detail later.

[0030] In some embodiments, after obtaining the comparison data T, a standard value A needs to be set as a benchmark for comparison with the comparison data T. The standard value A represents the critical rate of the effectiveness of the etching reaction. That is, when the characteristic gas generation rate is lower than A, it is considered that the etched material has been basically exhausted and the residual reaction has no effect on the device performance. Therefore, based on the relationship between the two, it can be determined whether the etching process has reached the etching endpoint.

[0031] In some specific embodiments, the standard value A is set using a pilot test calibration method, that is, the value of the standard value A is determined in advance, and this value is directly used to compare with the comparison data T in subsequent processes. Specifically, in the process of setting the standard value A, the standard (in terms of...) is first... The target etching layer is etched (with Si as the substrate) and a complete etching process is performed without determining the endpoint. The entire process is recorded and compared with the curve of the change of data T over time t. The moment when the target etching layer is just etched through and the reaction is transferred to the substrate is found in the recorded curve. Extracting the stable value before mutation That is, the plateau value when etching the target etched layer; extract the stable value after the mutation. That is, the new plateau value after entering the substrate layer, and the step amplitude is calculated. ,

[0032] Obtain step amplitude Then set the standard value A.

[0033] In some specific embodiments, k is set to 0.2 to leave a 20% margin to prevent noise triggering.

[0034] In some more specific embodiments, when T≥A, the etching process is determined not to have reached the etching endpoint; when T<A, the etching process is determined to have reached the etching endpoint; that is, when etching the target etched layer, the reactants are sufficient, the surface of the target etched layer film is exposed, and the reaction sites are saturated. If the generation rate is constant, and the comparison data T is greater than or equal to the standard value A, it indicates that the material is being significantly consumed, the etching is incomplete, and the etching process has not reached its endpoint. Once the target etched layer is complete, the substrate is exposed, and although... It will react with the Si in the substrate, but High selectivity for Si, leading to The generation rate approaches zero, so the comparison data T is less than the standard value A at this time. Material consumption is negligible, the etching is complete, and the etching process has reached the etching endpoint.

[0035] In some embodiments, the gas concentration signal is processed to establish the signal change rate r(t) of the characteristic gas at time t, and the signal change rate r(t) is used as the comparison data T, including...

[0036] in, Let be the concentration value of the characteristic gas at time t; The characteristic gas concentration sampling period.

[0037] In some specific embodiments, the signal change rate r(t) of the characteristic gas is selected as the comparison data T instead of the gas concentration signal of the characteristic gas because the characteristic gas is already present in the exhaust gas, meaning it will accumulate, and its concentration may become saturated and not decrease when the etching endpoint is reached. Furthermore, the gas concentration signal is affected by flow rate, pressure, and pipeline adsorption. On the other hand, the signal change rate r(t) can reflect the current generation rate of the characteristic gas in real time, and the generation rate of the characteristic gas can directly reflect the reaction intensity, thus making it easier to determine whether the etching endpoint has been reached.

[0038] More specifically, in the calculation of the signal change rate r(t), it is necessary to first set the sampling period, that is, set... The value when If the value is too small, it will increase the error in the calculation result, therefore, set... ≥2s, in this embodiment, is selected It lasts for 2 seconds. Let t be the characteristic gas concentration at the previous sampling time.

[0039] In some embodiments, the gas concentration signal is processed to obtain comparison data T. The process further includes processing the comparison data T to reduce the impact of noise from single-point abrupt changes. Specifically, after obtaining the comparison data, it needs to be processed to reduce the impact of noise from single-point abrupt changes on the comparison data T. This reduces the occurrence of concentration abrupt changes at a certain moment caused by the influence of the characteristic gas concentration, which could lead to inaccurate comparison data T. Examples include temporary blockage of airflow by bubbles in the exhaust pipe, changes in pumping speed due to fluctuations in vacuum pump speed, or electromagnetic noise from sensors. This reduces the likelihood of misjudging the etching endpoint.

[0040] In some specific embodiments, there are two ways to process the comparison data T, which will be described in turn below.

[0041] In some more specific embodiments, the comparison data T is processed to reduce the impact of noise from single-point mutations on the comparison data T, including selecting... To reduce the impact of noise from single-point abrupt changes on the comparison data T. Specifically, the noise level is related to the sampling period of the characteristic gas concentration. The ratio is inversely proportional, which is well known to those skilled in the art and will not be elaborated here. This applies when the characteristic gas concentration sampling period... When the sampling time is less than 2 seconds, interference from factors such as air bubbles and pressure fluctuations within the pipeline can cause instability in the characteristic gas concentration value. Furthermore, sampling too quickly can mistake these "false signals" for true reactions, causing the etching process to stop prematurely halfway through, resulting in the scrapping of the entire wafer. In addition, the characteristic gas concentration sampling period... The smaller the value, the greater the computational load within the same time period, potentially overloading the controller. Therefore, setting the characteristic gas concentration sampling period... This allows for coverage of more noise cycles, improving the signal-to-noise ratio. Simultaneously, the gas can travel from the semiconductor etching process chamber to the detection device within 2 seconds, improving detection accuracy without causing excessive delay. It is worth noting that different characteristic gas concentration sampling periods can be set depending on the location of the detection device on the exhaust pipe. For example, when the detection device is located far away on the exhaust pipe, the sampling period for the characteristic gas concentration can be appropriately increased. There are no restrictions here; the specific settings should be based on the testing requirements.

[0042] In some other embodiments, the comparison data T is processed to reduce the impact of noise from single-point mutations on the comparison data T, including, Calculate the moving average of the rate of change of the signal r(t) at time t. , as the comparison data T;

[0043] Where N is the number of sampling points participating in the averaging; i is the index variable; The sampling period for the characteristic gas concentration; Let be the instantaneous rate of change of the historical times of the i sampling points before time t.

[0044] Specifically, in addition to setting the characteristic gas concentration sampling period In addition, the signal change rate r(t) can also be processed. During the detection process, even the characteristic gas concentration sampling period... If the signal change rate r(t) is greater than or equal to 2s, the calculated signal change rate r(t) may be inaccurate due to pressure interference or electrical interference. Therefore, the consistency of the signal change rate r(t) at multiple consecutive points is used as the criterion to reduce the probability of false triggering by single-point noise.

[0045] For example, suppose that at t=10s, the system has stored the values ​​of the signal change rate r(t) for the most recent 5 moments; at t=10s, the index variable i=0, The value is 8 ppm / s, at which point the data contains noise; at t=8s, the index variable i=1. The value is 25 ppm / s; at t=6s, the index variable i=2. The value is 24 ppm / s; at t=4s, the index variable i=3. The value is 26 ppm / s; at t=2s, the index variable i=4. The value is 23 ppm / s. At this point, the standard value A is 10 ppm / s.

[0046] Now calculate the moving average value at t=10s.

[0047] at this time If the noise level is greater than 10 ppm / s, meaning the comparison data T is greater than the standard value A, the endpoint is not triggered, and the noise is successfully suppressed. If the average value is not used at this point, i.e., r(t10) = 8 ppm / s, then 8 ppm / s < 10 ppm / s, meaning the comparison data T is less than the standard value A, the endpoint is falsely triggered, and the noise cannot be suppressed.

[0048] In some embodiments, when T < A, the etching process is determined to have reached the etching endpoint, including: Subtract the moving average from the already determined time t. The algorithm delay is used to obtain the actual time when the etching process reaches the etching endpoint. ,

[0049] in, To calculate the moving average The inherent delay introduced by time; The time was set to prevent misjudgment.

[0050] In some specific embodiments, the moving average The algorithm suffers from information confirmation delay. For example, if five data points are collected at t=10s, we can confirm that the trend from t=0s to t=10s is downward, and the moving average... The value is the average from t=0s to t=10s, therefore the actual inflection point of the characteristic gas concentration should occur at the midpoint between the averages; specifically, for example, if t=10s is the etching endpoint, then r(t12), r(t14), and r(t16) can all be considered to be 0ppm / s at this time;

[0051] That is, the etching endpoint can be determined at t=16s, but the actual time to reach the etching endpoint is 10s. Therefore, the moving average value needs to be subtracted from the determined time t. In addition to the algorithm delay, the valve closing time also needs to be subtracted, i.e., the time set to prevent misjudgment, in order to obtain the accurate actual time when the etching process reaches the etching endpoint. .

[0052] In some more specific embodiments, the moving average is calculated. Inherent delay introduced by time for,

[0053] Where N is the specific number of samples, The characteristic gas concentration sampling period.

[0054] This allows us to determine how to calculate the moving average. Inherent delay introduced by time The specific value.

[0055] In some more specific embodiments, To prevent misjudgment of the set time, it can be a mechanical delay when the valve closes, or a false fluctuation in the signal; The value range is set manually, usually between 0.5S and 3S, for example, in... During the etching process, =1s, during the TiN etching process =2s; In actual calculations, different values ​​are set according to different needs.

[0056] In some specific embodiments, the etching process is either vapor phase chemical etching or remote plasma etching. Specifically, in conventional plasma etching, the plasma generates a large number of active particles, such as... , or etc., make The concentration is diluted, which causes significant interference to the detection signal and makes the detection results inaccurate. Therefore, vapor phase chemical etching and remote plasma etching are suitable for the above-mentioned endpoint detection processes because they do not involve plasma and produce a single product.

[0057] An embodiment of the present invention also discloses a detection system for implementing the above-described etching endpoint detection method; the detection system includes a semiconductor etching process chamber, an exhaust gas emission pipeline, and a detection device; The exhaust gas pipeline is connected to the semiconductor etching process chamber to discharge the products and by-products inside the semiconductor etching process chamber; The detection device is installed in the exhaust gas pipeline to detect the concentration of characteristic gases in real time.

[0058] In some embodiments, a semiconductor etching process chamber is used to place the wafer, where the reaction takes place. An exhaust gas duct is located at the bottom of the semiconductor etching process chamber and communicates with its interior. The exhaust gas duct discharges processing products and byproducts generated during wafer processing, ensuring that the processing exhaust gas does not interfere with the wafer processing process. Specifically, the exhaust gas duct can be installed by bonding, snap-fitting, or integral molding, etc., without limitation, as long as the exhaust gas duct can be fixed to the semiconductor etching process chamber and communicate with its interior to discharge processing products and byproducts.

[0059] In some specific embodiments, the detection device is located inside the exhaust gas emission pipe. The method of installation can be adhesive, snap-fit, or bolted, etc., without limitation, as long as it can detect the characteristic gases of the exhaust gas emission pipe.

[0060] In some embodiments, Figure 2 The characteristic gas of the embodiments of the present invention ( The concentration curve of the gas is shown in the figure; where the horizontal axis X represents the reaction time in seconds and the vertical axis Y represents the gas concentration in pmm. Figure 3 The characteristic gas of the embodiments of the present invention ( The graph shows the rate of change of the concentration signal, r(t); where the horizontal axis X represents the reaction time in seconds, and the vertical axis Y represents the rate of change in pmm / s. Specifically, the detection device monitors the characteristic gases in the cleaning process in real time. The concentration. At the start of the cleaning process, The concentration rose rapidly, corresponding to Figure 2 and Figure 3 The curve from 0 to 55 seconds; the chamber cleanliness reaches a stable state, corresponding to... Figure 2 and Figure 3 55-94s curve The concentration remained stable; then, after 94 seconds, when the silicon-based deposits in the chamber were almost completely removed, The generation rate of [something] will drop sharply, resulting in a clear inflection point in its concentration (around 94s). This inflection point of 94s is determined to be the cleaning endpoint.

[0061] The principle behind the etching endpoint detection method and system for plasma-free etching processes disclosed in this application is as follows: In vapor-phase chemical etching or remote plasma etching, the reactant gas undergoes a purely chemical reaction with the wafer surface to generate a single volatile product, such as... The product instantly detaches from the surface and enters the exhaust gas pipeline along with the carrier gas. The detection device is installed in the straight section of the pipeline, using FTIR, TDLAS, or other techniques to integrate the characteristic absorption peak spectrum, while simultaneously sampling the characteristic gas concentration periodically. The transport time of the covered gas from the chamber to the detection device is ≥2 seconds. The sampling period for different characteristic gas concentrations can be adjusted according to the different settings of the detection device. This invention achieves synchronization between reaction and detection time. Comparison data T is calculated based on the characteristic gas concentration signal and compared with the standard value A to determine whether the etching process has reached its endpoint. Furthermore, by processing the signal change rate r(t), the accuracy of the judgment can be improved, reducing the possibility of inaccurate endpoint determination caused by single-point noise mutations. This invention provides real-time endpoint detection capability based on the chemical reaction nature of plasma-free etching processes. Specifically, by detecting the change rate r(t) of the characteristic gas concentration signal, it can sensitively capture abrupt changes at the etching interface, offering greater resistance to baseline drift and more accurate judgment than absolute value detection. Moreover, the detection process only requires adding a mature gas concentration meter to the existing equipment's exhaust gas pipeline and upgrading the control system software, resulting in low modification costs.

[0062] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for etch endpoint detection for a plasmaless etch process, the method comprising: The etching process does not generate plasma in a semiconductor etching process chamber, and the etching endpoint detection method comprises: A detection device is arranged on an exhaust pipeline of the semiconductor etching process chamber; The detection device is started to detect the gas concentration of the characteristic gas in the exhaust pipeline in real time, and a gas concentration signal is obtained; The gas concentration signal is processed to establish a signal change rate r(t) of the characteristic gas at t time, and the signal change rate r(t) is taken as comparison data T; A standard value A is set, and the comparison data T is compared with the standard value A; When T≥A, it is determined that the etching process has not reached the etching endpoint; When T<A, it is determined that the etching process has reached the etching endpoint.

2. The etch endpoint detection method of claim 1, wherein, The signal change rate r(t) of the characteristic gas at t time comprises, wherein, is the concentration value of the characteristic gas at time t; is the characteristic gas concentration sampling period.

3. The etch endpoint detection method of claim 2, wherein, The gas concentration signal is processed to establish a signal change rate r(t) of the characteristic gas at t time, and the signal change rate r(t) is taken as comparison data T, which comprises, The comparison data T is processed to reduce the influence of single-point mutation noise on the comparison data T.

4. The etch endpoint detection method of claim 3, wherein, The comparison data T is processed to reduce the influence of single-point mutation noise on the comparison data T, It comprises, selecting to reduce the effect of noise from single point mutations on the contrast data T.

5. The etch endpoint detection method of claim 3, wherein, The comparison data T is processed to reduce the influence of single-point mutation noise on the comparison data T, which comprises, calculating a moving average value of the signal change rate r(t) at time t , as the comparison data T; Wherein, N is the number of sampling points participating in the average; i is an index variable; is the feature gas concentration sampling period; is the instantaneous rate of change of the historical time of the i sampling points before t time.

6. The etch endpoint detection method of claim 5, wherein, When T<A, it is determined that the etching process has reached the etching endpoint, which comprises, Subtracting the sliding average from the t time that has been determined The algorithm delay of the sliding average, to obtain the actual time of the etching process to reach the etching endpoint , wherein, is the intrinsic delay introduced when calculating the moving average; is the intrinsic delay introduced when calculating the moving average; is the time set to prevent false positives.

7. The etch endpoint detection method of any of claims 1-6, wherein, The etching process is gas phase chemical etching or remote plasma etching.

8. The etch endpoint detection method of any of claims 1-6, wherein, The characteristic gas is a corrosive gas.

9. The etch endpoint detection method of claim 8, wherein, The corrosive gas is one of , , , , , or .

10. A detection system characterized by, The detection system comprises a semiconductor etching process chamber, an exhaust pipeline and a detection device for implementing the etching endpoint detection method of any one of claims 1-9; The exhaust pipeline is in communication with the semiconductor etching process chamber to discharge products and by-products in the semiconductor etching process chamber; The detection device is arranged on the exhaust pipeline to detect the concentration of the characteristic gas in real time.

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