Etch endpoint detection method and detection system for plasmaless etch processes

Abstract

The application discloses an etching endpoint detection method and system for a plasma-free etching process, the etching endpoint detection method comprising: obtaining a gas concentration signal; processing the gas concentration signal to establish a signal change rate r(t) of a characteristic gas at time 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 >= A, determining that the etching process has not reached an etching endpoint; and when T < A, determining that the etching process has reached the etching endpoint. The detection system comprises a semiconductor etching process chamber, an exhaust pipeline and a detection device; the exhaust pipeline is in communication with the semiconductor etching process chamber to discharge products and byproducts in the semiconductor etching process chamber; and the detection device is arranged on the exhaust pipeline to detect the concentration of the characteristic gas in real time. The application solves the problem of the lack of real-time and high-precision endpoint detection capability of a plasma-free etching device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor detection, and in particular to an etching endpoint detection method and system for a plasma-free etching process. BACKGROUND

[0002] In a plasma-free etching process (such as vapor phase chemical etching, 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] The prior art mainly uses a fixed-time etching scheme, which has significant defects, such as its inability to perceive the etching progress in real time, which easily leads to under-etching (residual) or over-etching (damage to the underlying material), affecting product yield, and the etching rate is affected by multiple factors such as temperature, pressure, and gas flow, so the fixed-time method cannot adapt to process fluctuations. In addition, for wafers with multi-layer film structures (such as polysilicon / silicon dioxide), the fixed-time method cannot accurately determine the interlayer transition point.

[0004] Therefore, it is necessary to provide a new etching endpoint detection method and system for a plasma-free etching process to solve the above problems in the prior art. SUMMARY

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

[0006] To solve the above technical problems, according to an embodiment of the present application, an etching endpoint detection method for a plasma-free etching process is provided, the etching process does not generate plasma in a semiconductor etching process chamber, and the etching endpoint detection method comprises:

[0007] A detection device is arranged on an exhaust pipe of the semiconductor etching process chamber;

[0008] The detection device is started, the gas concentration of a characteristic gas in the exhaust pipe is detected in real time, and a gas concentration signal is obtained;

[0009] The gas concentration signal is processed, a signal change rate r(t) of the characteristic gas at time t is established, and the signal change rate r(t) is taken as comparison data T;

[0010] A standard value A is set, and the comparison data T is compared with the standard value A;

[0011] When T≥A, it is determined that the etching process has not reached the etching endpoint;

[0012] When T<A, it is determined that the etching process reaches the etching endpoint.

[0013] According to an embodiment of the present application, the signal change rate r(t) of the characteristic gas at the time t is established by processing the gas concentration signal, and the signal change rate r(t) is taken as the comparison data T, which comprises:

[0014]

[0015] Wherein, C(t) is the concentration value of the characteristic gas at the time t; is the sampling period of the characteristic gas concentration. According to an embodiment of the present application, the signal change rate r(t) of the characteristic gas at the time t is established by processing the gas concentration signal, and the signal change rate r(t) is taken as the comparison data T, which comprises:

[0016] The comparison data T is processed to reduce the influence of the noise of single-point mutation on the comparison data T.

[0017] According to an embodiment of the present application, the comparison data T is processed to reduce the influence of the noise of single-point mutation on the comparison data T, which comprises:

[0018] The comparison data T is selected

[0019] to reduce the influence of the noise of single-point mutation on the comparison data T.

[0020] According to an embodiment of the present application, the comparison data T is processed to reduce the influence of the noise of single-point mutation on the comparison data T, which comprises:

[0021] The sliding average value of the signal change rate r(t) at the time t is calculated as the comparison data T;

[0022]

[0023] Wherein, N is the number of sampling points participating in the average; i is an index variable; is the sampling period of the characteristic gas concentration; is the instantaneous change rate of the historical time of the i sampling points before the time t.

[0024] According to an embodiment of the present application, when T<A, it is determined that the etching process reaches the etching endpoint, which comprises:

[0025] The algorithm of the sliding average value which has been determined is delayed to obtain the actual time at which the etching process reaches the etching endpoint.

[0026] ​

[0027] wherein, is the time to calculate the moving average the inherent delay introduced when is the time set to prevent false positives.

[0028] According to embodiments of the present application, the etching process is a vapor phase chemical etching or a remote plasma etching.

[0029] According to embodiments of the present application, the characteristic gas is a corrosive gas.

[0030] According to embodiments of the present application, the corrosive gas is , , , , , or .

[0031] A detection system for implementing the etching endpoint detection method described above; the detection system comprises a semiconductor etching process chamber, an exhaust pipe and a detection device;

[0032] The exhaust pipe is in communication with the semiconductor etching process chamber to discharge the products and byproducts in the semiconductor etching process chamber;

[0033] The detection device is arranged in the exhaust pipe to detect the concentration of the characteristic gas in real time.

[0034] By using the above technical solution, in the vapor phase chemical etching or the remote plasma etching, the reaction gas and the wafer surface have a pure chemical reaction to generate a single volatile product, for example , which instantaneously separates from the surface and enters the exhaust pipe with the carrier gas. The detection device is arranged in the straight pipe section of the pipe, and FTIR or TDLAS or other technologies are used to integrate the characteristic absorption peak spectrum, and the characteristic gas concentration sampling period ≥ 2s covers the transport time of the gas from the chamber to the detection device, and different characteristic gas concentration sampling periods can be adjusted according to the different arrangement positions of the detection device , the reaction and detection time is synchronized. According to the characteristic gas concentration signal, the comparison data T is calculated, the comparison data T is compared with the standard value A, and whether the etching process reaches the endpoint is determined. In addition, by processing the signal change rate r(t), the accuracy of the judgment can be improved, and the possibility of inaccurate detection endpoint judgment caused by single-point noise mutation can be reduced. The present application provides real-time endpoint detection capability for plasma-free etching process based on the nature of chemical reaction, that is, by detecting the characteristic gas concentration signal change rate r(t), the mutation of the etching interface can be sensitively captured, which is more resistant to baseline drift than absolute value detection, more accurate judgment, and at the same time, only mature gas concentration instruments need to be installed in the existing equipment exhaust pipeline during the detection process, and the control system needs to be upgraded, which has low modification cost. BRIEF DESCRIPTION OF DRAWINGS

[0035] Fig. 1 A schematic diagram of the steps of an etching endpoint detection method for a plasma-free etching process according to an embodiment of the present application;

[0036] Fig. 2 A concentration curve of a characteristic gas ( ) according to an embodiment of the present application; wherein the abscissa X is the reaction time, the unit is s; the ordinate Y is the gas concentration, the unit is pmm;

[0037] Fig. 3 A curve of the signal change rate r(t) of the concentration of a characteristic gas ( ) according to an embodiment of the present application; wherein the abscissa X is the reaction time, the unit is s; the ordinate Y is the change rate, the unit is pmm / s. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. Unless otherwise defined, the technical terms or scientific terms used herein should be understood as the usual meaning understood by those skilled in the art in the field of the present application. The words such as "include" and similar words used herein mean that the elements or objects before the words cover the elements or objects listed after the words and their equivalents, and do not exclude other elements or objects.

[0039] The specific embodiments of the present application will be further described below. Figs. 1-3

[0040] ​Embodiments of the present application provide an etching endpoint detection method for a plasma-free etching process, wherein the plasma-free etching process does not introduce plasma in the etching process, which includes gas phase chemical etching. Such process completely relies on high temperature or chemical activity 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, when using HF gas etching The whole reaction process is gaseous by catalysis with anhydrous ethanol, which can effectively avoid the adhesion effect of micro-nano structures in the release process due to liquid surface tension; the etching process does not produce plasma in the semiconductor etching process chamber, and the detection method comprises:

[0041] S1, a detection device is arranged on the tail gas discharge pipeline of the semiconductor etching process chamber;

[0042] S2, the detection device is started, the gas concentration of the characteristic gas in the tail gas discharge pipeline is detected in real time, and a gas concentration signal is obtained;

[0043] S3, the gas concentration signal is processed, the signal change rate r(t) of the characteristic gas at t time is established, and the signal change rate r(t) is taken as the comparison data T;

[0044] S4, a standard value A is set, and the comparison data T is compared with the standard value A;

[0045] S5, when T≥A, it is determined that the etching process has not reached the etching endpoint;

[0046] When T<A, it is determined that the etching process has reached the etching endpoint.

[0047] In some embodiments, the detection device is arranged inside the tail gas discharge pipeline of the semiconductor etching process chamber, so that the gas passing through the tail gas discharge pipeline can pass through the detection device at the same time, thereby facilitating the detection of the gas passing through the tail gas discharge pipeline.

[0048] In some specific embodiments, the detection device can use one of FTIR (Fourier Transform Infrared Spectroscopy), TDLAS (Tunable Diode Laser Absorption Spectroscopy), NDIR (Non-Dispersive Infrared Technology) or self-excited plasma OES (Optical Emission Spectroscopy) in the detection process, which is not limited in particular, and the corresponding detection method is selected according to the use requirement in actual use.

[0049] In some embodiments, the gas concentration of the characteristic gas passing through the tail gas discharge pipeline needs to be detected in the detection process; wherein the characteristic gas is a by-product produced after reaction in the semiconductor etching process chamber, which is a corrosive gas, and it can be 、 、 、 , , or These gases have characteristic absorption peaks in the infrared spectrum, which facilitates real-time concentration detection using the above optical detection technology; at the same time, in gas-phase chemical etching or remote plasma etching, the change in the concentration of these gases directly reflects the degree of etching reaction; when etching reaches the end point, i.e., the etched layer is completely removed, the generation rate of these characteristic gases will significantly decrease, and the concentration tends to be stable or decrease, thereby facilitating the determination of whether the etching end point is reached according to the concentration change of the characteristic gas. For example, taking the target etching layer as , the substrate layer as Si, and as the process gas for etching reaction, the reaction when etching is performed, i.e., the target etching layer is etched, is

[0050]

[0051] The reaction when etching is performed on the substrate layer is

[0052]

[0053] During etching, only the target etching layer is etched, i.e., the substrate layer is not etched, and both the target etching layer and the substrate layer are etched, so that , and thus the concentration of can be detected to determine the current etching position, thereby determining whether the etching is completed.

[0054] In some embodiments, after obtaining the gas concentration signal, the gas concentration signal needs to be processed to obtain comparison data T that can be used for comparison; specifically, since the absolute value of the gas concentration signal is affected by multiple factors such as gas flow, chamber pressure, temperature fluctuation, pipeline adsorption / desorption, etc., it cannot stably reflect the etching progress, and thus it must be converted into comparison data T to accurately compare. 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 comparison data T is the signal change rate r(t) of the characteristic gas, which will be described in detail later.

[0055] In some embodiments, when the comparison data T is obtained, a standard value A needs to be set as a reference for comparison with the comparison data T; wherein the standard value A represents the critical rate of the effectiveness of the etching reaction, that is, when the generation rate of the characteristic gas is lower than A, it is considered that the etched material has been substantially depleted, and the residual reaction has no effect on the device performance, and thus according to the mutual relationship between the two, it can be determined whether the etching process reaches the etching end point.

[0056] In some specific embodiments, the standard value A is set by a pilot test calibration method, i.e., the value of the standard value A is determined in advance, and the value is directly used for comparison with the comparison data T in the subsequent process. Specifically, in the process of setting the standard value A, first, the standard (target etching layer, Si as the substrate layer) is subjected to complete etching without end-point determination, and the change curve of the comparison data T with time t is recorded throughout the process; and the time when the target etching layer is just etched through and the reaction enters the substrate layer is found in the recorded change curve graph.

[0057] Extracting the stable value before mutation , i.e., the platform value when etching the target etching layer; extracting the stable value after mutation , i.e., the new platform value after entering the substrate layer, and calculating the step amplitude

[0058]

[0059] Obtaining the step amplitude Setting the standard value A,

[0060]

[0061] In some specific embodiments, k is 0.2, leaving a 20% margin to prevent noise triggering.

[0062] In some more specific embodiments, when T≥A, it is determined that the etching process has not reached the etching end point; when T The generation rate is constant, and at this time, the comparison data T is greater than or equal to the standard value A, indicating that the material is being significantly consumed, and the etching is not completed, i.e., the etching process has not reached the etching end point. After the target etching layer is etched, the substrate layer is exposed, and although will react with the Si of the substrate layer, the selectivity to Si is very high, resulting in the generation rate tends to zero, so at this time, the comparison data T is less than the standard value A, the material consumption is negligible, and the etching is completed, i.e., the etching process reaches the etching end point.

[0063] 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,

[0064]

[0065] wherein, is the concentration value of the characteristic gas at time t; ​​The sampling period of the characteristic gas concentration.

[0066] 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 as the comparison data T because the characteristic gas has already been emitted in the exhaust gas, i.e., it accumulates, and its concentration may be saturated and not decreased when the etching endpoint is reached, and the gas concentration signal is affected by the flow rate, pressure, and pipeline adsorption; while 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, thereby facilitating the determination of whether the etching endpoint is reached.

[0067] More specifically, in the calculation process of the signal change rate r(t), the sampling period needs to be set first, i.e., the value of is set, and when is too small, the error of the calculation result will increase, and therefore ≥ 2s, and in the present embodiment, is selected as 2s. is the characteristic gas concentration at the last sampling time of the t moment.

[0068] In some embodiments, the gas concentration signal is processed to obtain the comparison data T, and the comparison data T is further processed to reduce the influence of single-point mutation noise on the comparison data T. Specifically, after the comparison data is obtained, the comparison data needs to be processed to reduce the influence of single-point mutation noise on the comparison data T, i.e., to reduce the occurrence of the inaccuracy of the comparison data T caused by the concentration mutation of the characteristic gas concentration at a certain moment, such as the temporary blockage of the gas flow by the bubbles in the exhaust pipeline, or the change in the pumping speed caused by the fluctuation of the speed of the vacuum pump, or the electromagnetic noise of the sensor, etc. Thus, the misjudgment of the etching endpoint is reduced.

[0069] In some specific embodiments, there are two processing methods for the comparison data T, which are introduced in turn.

[0070] In some more specific embodiments, the comparison data T is processed to reduce the influence of single-point mutation noise on the comparison data T, including selecting to reduce the influence of single-point mutation noise on the comparison data T. Specifically, the noise is inversely proportional to the sampling period of the characteristic gas concentration , which is known to those skilled in the art and will not be described here in detail. When the sampling period of the characteristic gas concentration is less than 2s, the interference of factors such as bubbles and pressure fluctuations in the pipeline will make the characteristic gas concentration unstable, and too fast sampling will regard these "false signals" as true reactions, thereby causing the etching to be stopped at the middle of the process, resulting in the scrap of the entire wafer. In addition, the sampling period of the characteristic gas concentration The smaller it is, the greater the amount of calculation in the same time, which may cause the controller overload. Setting the characteristic gas concentration sampling period , more noise periods can be covered, and the signal-to-noise ratio is improved. At the same time, the gas can complete the path from the semiconductor etching process chamber to the detection device within 2s, and the detection accuracy is improved without causing excessive delay. It is worth noting that, according to the different positions of the detection device on the tail gas discharge pipeline, different characteristic gas concentration sampling periods can be set, for example, when the detection device is set far away on the tail gas discharge pipeline, the characteristic gas concentration sampling period may be appropriately increased, which is not limited here, and is set according to the detection requirements.

[0071] In some other embodiments, the comparison data T is processed to reduce the influence of single-point mutation noise on the comparison data T, including,

[0072] The moving average value of the signal change rate r(t) at time t is calculated as the comparison data T;

[0073]

[0074] Wherein, N is the number of sampling points participating in the average; i is the index variable; is the characteristic gas concentration sampling period; is the instantaneous change rate of the historical time of the i sampling points before time t.

[0075] Specifically, in addition to setting the characteristic gas concentration sampling period , the signal change rate r(t) can also be processed. Even if the characteristic gas concentration sampling period is greater than or equal to 2s, the calculated signal change rate r(t) may also be inaccurate due to pressure interference or electrical interference, so the consistency of the signal change rate r(t) of the continuous multiple points is taken as the basis for judgment, thereby reducing the probability of single-point noise error.

[0076] For example, assuming that at t=10s, the system has stored the values of the signal change rate r(t) at the last 5 times; at t=10s, the index variable i=0, is 8ppm / s, which is noise-containing data; at t=8s, the index variable i=1, is 25ppm / s; at t=6s, the index variable i=2, is 24ppm / s; at t=4s, the index variable i=3, is 26ppm / s; at t=2s, the index variable i=4, 23 ppm / s. At this time, the standard value A is 10 ppm / s.

[0077] At this time, the sliding average value of t = 10 s is calculated,

[0078]

[0079] At this time > 10 ppm / s, that is, the comparison data T is greater than the standard value A, the endpoint is not triggered, and the noise is successfully suppressed. At this time, the average value is not selected, that is, r(t10) = 8 ppm / s, at this time, 8 ppm / s < 10 ppm / s, that is, the comparison data T is less than the standard value A, the endpoint is triggered by mistake, and the noise cannot be suppressed.

[0080] In some embodiments, when T < A, it is determined that the etching process reaches the etching endpoint, including,

[0081] The algorithm delay of the sliding average value of the already determined t time is obtained, and the actual time when the etching process reaches the etching endpoint ,

[0082]

[0083] wherein, is the inherent delay introduced when calculating the sliding average value ; is the time set to prevent misjudgment.

[0084] In some specific embodiments, the algorithm of the sliding average value exists information confirmation delay, that is, for example, at t = 10 s, five data points are collected, and it can be confirmed that the trend from t = 0 s to t = 10 s is downward, and the sliding average value is the average value from t = 0 s to t = 10 s, so it is considered that the actual turning point of the feature gas concentration should occur at the midpoint between the averages. Specifically, for example, t = 10 s is the etching endpoint, then r(t12), r(t14) and r(t16) can all be considered as 0 ppm / s at this time; at this time,

[0085]

[0086] That is, t = 16 s can be determined to have reached the etching endpoint, and the actual time when the etching endpoint is reached is 10 s, so the algorithm delay of the sliding average value of the already determined t time is needed; in addition, the closing time of the valve, that is, the time set to prevent misjudgment, needs to be subtracted, so as to obtain the accurate actual time when the etching process reaches the etching endpoint .

[0087] In some more specific embodiments, the sliding average is calculated the inherent delay introduced when is,

[0088]

[0089] wherein N is a specific number of samples, is a sampling period of the concentration of the characteristic gas.

[0090] thereby being able to determine the specific value of the inherent delay introduced when the sliding average is calculated

[0091] In some more specific embodiments, is a time set to prevent false positives, which can be a mechanical delay when the valve is closed, or a signal pseudo-oscillation; is set by a person, and is usually 0.5S-3S, for example in etching, =1s, in the TiN etching process, =2s; in actual calculation, different values are set according to different requirements.

[0092] In some specific embodiments, the etching process is gas-phase chemical etching or remote plasma etching. Specifically, in conventional plasma etching, a large number of active particles are generated by plasma, such as , or , so that the concentration is diluted, thereby causing a large interference of the detection signal, and making the detection result inaccurate; that is, the gas-phase chemical etching and the remote plasma etching are suitable for the above-mentioned end-point detection process because they do not have plasma and the products are single.

[0093] Embodiments of the present application also disclose a detection system for implementing the above-mentioned etching end-point detection method; the detection system comprises a semiconductor etching process chamber, an exhaust pipeline and a detection device.

[0094] The exhaust pipeline is in communication with the semiconductor etching process chamber to discharge the products and by-products in the semiconductor etching process chamber;

[0095] The detection device is arranged in the exhaust pipeline to detect the concentration of the characteristic gas in real time.

[0096] ​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.

[0097] 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.

[0098] In some embodiments, Fig. 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. Fig. 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 Fig. 2 and Fig. 3 The curve from 0 to 55 seconds; the chamber cleanliness reaches a stable state, corresponding to... Fig. 2 and Fig. 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.

[0099] 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. ≥2s transport time of the cover gas from the chamber to the detection device, which can be adjusted according to different detection device settings to adjust different characteristic gas concentration sampling periods , and the comparison data T is compared with the standard value A to determine whether the etching process has reached the endpoint. In addition, by processing the signal change rate r(t), the accuracy of the judgment can be improved, and the possibility of inaccurate detection of the endpoint caused by single-point noise mutation can be reduced. The present application provides real-time endpoint detection capability for plasma-free etching process based on the nature of chemical reaction, that is, by detecting the characteristic gas concentration signal change rate r(t), the abrupt change of the etching interface can be captured sensitively, which is more resistant to baseline drift than absolute value detection, more accurate in judgment, and only needs to install a mature gas concentration instrument on the existing equipment exhaust pipeline and upgrade the software of the control system during the detection process, with low modification cost.

[0100] Although the embodiments of the present application have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to the embodiments. However, it should be understood that such modifications and changes are within the scope and spirit of the present application as described in the claims. Moreover, the present application described herein can have other embodiments and can be implemented or realized 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; processing the gas concentration signal to establish a signal rate of change r(t) of the characteristic gas at time t, and calculating a moving average of the signal rate of change r(t) at time t 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 reaches the etching endpoint; the actual time when the etching process reaches the etching endpoint is obtained by subtracting the algorithm delay from the t time that has been determined ,​ wherein, to calculate the moving average the inherent delay introduced when the time set to prevent false positives.

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 the signal change rate r(t) of the characteristic gas at t time, and the signal change rate r(t) is taken as the 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, Comprise, 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, said computing a moving average of the signal rate of change r(t) at time t comprising, 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 any of claims 1-5, wherein, The etching process is gas phase chemical etching or remote plasma etching.

7. The etch endpoint detection method of any of claims 1-5, wherein, The characteristic gas is a corrosive gas.

8. The etch endpoint detection method of claim 7, wherein, The corrosive gas is one of , , , , , or .

9. A detection system characterized by, The etching endpoint detection method according to any one of claims 1-8 is implemented; the detection system comprises a semiconductor etching process chamber, an exhaust pipeline and a detection device; The exhaust pipeline is communicated with the semiconductor etching process chamber to discharge the products and byproducts 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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