WO2010081343A1

WO2010081343A1 - Endpoint control method and device of semiconductor etch process

Info

Publication number: WO2010081343A1
Application number: PCT/CN2009/074695
Authority: WO
Inventors: 张善贵
Original assignee: 北京北方微电子基地设备工艺研究中心有限责任公司
Priority date: 2009-01-14
Filing date: 2009-10-29
Publication date: 2010-07-22
Also published as: CN101465289B; CN101465289A

Abstract

An etch endpoint control method is provided,which comprises: acquiring realtime optical interference detection spectrum lines, searching a wave peak signal and a wave valley signal in the optical interference detection spectrum lines to acquire an etch period of the current process,using the etch thickness required,the thickness of a wafer etched in one etch period and the etch period of the current process，an endpoint control is carried on the etch process.An etch endpoint control device is also provided.

Description

End point control method and device for semiconductor etching process

The present invention relates to the field of semiconductor process control technology, and in particular, to an endpoint control method and apparatus for a semiconductor etching process. Background technique

Endpoint Detection of the process is a key technology in the production of semiconductor processes. In recent years, as the critical dimensions of etching have gradually decreased and the structure of the wafer layer has become more complex, the requirements for endpoint control have become higher and higher during the etching process.

In an ideal etch system, the same process etches the same type of silicon wafers with the same etch rate, and the etch time should be the same. However, in the actual process etching process, due to the system itself or other interference, the etching end time and the etching rate fluctuate or abnormal, resulting in the uniformity of etching between the sheets cannot be achieved. Seriously, it will also cause waste. Therefore, real-time monitoring of the etch endpoint is necessary by predicting the process endpoint time. Especially for some complex membrane processes, how to achieve accurate control of the end points of the process has become a key issue in the etching process.

The existing control methods for the process end point are mainly OES (Optical Emission Spectroscopy) methods. The optical emission optical language detection system is mainly based on the on-line optical language detection device for real-time detection of the spectrum emitted by the plasma. Since the etching to different material layers, the optical language will change significantly, and the etching process is different by monitoring the etching process. The intensity of the emission line of the reactant or product when the substance of the layer is used to determine the end point of the etch. Referring to FIG. 1, a schematic diagram of a obtained optical signal as a function of process time, wherein the spectral intensity signal substantially maintains an intensity value in a normal etch process (Normalize Time) 101, and when the end point is reached, the spectral intensity value Rapid decline. Specifically, the manner in which the process end point is obtained may include a threshold (including a relative value and an absolute value) method or a slope (Slope) method.

The basic principles of the threshold method and the slope method are similar. Taking the line of Fig. 1 as an example, the following steps may be generally included: first obtaining a process optical signal; then, passing a spectral intensity threshold or a spectral intensity slope parameter in the figure 1 is to find the trigger point (Trigger Point) 102 of the optical signal, that is, the turning point of the optical signal strength; finally, if all the signal points starting from the Trigger Point satisfy the threshold condition in the preset Satisfaction Time 103, then The process end time is equal to the Trigger Point time point of the optical signal plus the preset Satisfaction Time 103.

For a process in which the general wafer film is relatively simple and only needs to capture the end point between the layers, the above optical emission spectroscopy can basically accurately collect the end point of the process: due to the layer-to-layer process during the etching process Different polymers are produced, and the intensity of the end point spectral curve fluctuates significantly when the layer is switched. The end point collection software can easily determine the process end point by the magnitude and trend of the signal change.

However, for some processes where the film layer is relatively complicated and needs to capture the end point in the layer, the above-mentioned optical emission spectroscopy is generally difficult to accurately capture the end point of the process because the intensity signal of the end point spectral curve does not change significantly during the etching process.

In summary, one technical problem that is urgently needed by those skilled in the art is how to innovatively propose a process control method that can accurately obtain the process end point to improve product productivity. Summary of the invention

The technical problem to be solved by the present invention is to provide an end point control method and apparatus for a semiconductor etching process, which can accurately predict the process end time and better perform process control to improve product productivity and production quality.

In order to solve the above technical problem, the present invention provides an end point control method for a semiconductor etching process, comprising: acquiring a real-time optical interference detecting line; searching in the optical interference detecting line The Sopo signal and/or the valley signal, and then the etching cycle of the process is obtained; the thickness of the etching required by the process, the thickness of the silicon wafer which can be etched by a single etching cycle, and the etching of the process Cycle, the end point control of this etching process. The etching cycle of the process, real-time calculation to the current time point t, the number of cycles passed by the etching process; the thickness of the silicon wafer which can be etched according to the thickness of the etching required for the process and the single etching cycle , to obtain the number of cycles required for the process end point; by comparing the above two cycle numbers, it is known whether the current time point t reaches the process end point, and then performs corresponding control. The etching period of the secondary process and the thickness of the silicon wafer which can be etched in a single etching cycle, and the thickness of the etched silicon wafer at the current time point t is calculated in real time; by comparing the calculated thickness with the current process The thickness to be etched is used to know whether the current time point t reaches the end of the process, and then the corresponding control is performed. The thickness of the etching required for the secondary process and the thickness of the silicon wafer which can be etched by a single etching cycle, and the number of cycles required for the process end point; further, according to the etching cycle of the process, the end point prediction of the process is obtained. Time; by comparing the current time point t with the end point prediction time, it is known whether the current time point t reaches the process end point, and then performs corresponding control.

Preferably, the method may further include: pre-processing the acquired optical interference detection line, the pre-processing including filtering processing and/or delay processing, wherein the delay processing is used to ignore the detection line for a period of time Invalid signal.

Preferably, the peak signal and the search for the peak signal in the optical interference detection line can be

/ or trough signal: to determine the trend of the optical signal in the optical interference detection line; if the optical signal first shows an upward trend, start the search process of the peak and valley between the peak search; if the optical signal is presented first A downward trend is initiated to initiate a search process between peaks and valleys beginning with a trough search. And/or trough signals: search for crest signals directly; and/or, search for trough signals directly. Preferably, the method may further include: for the peak or trough signal obtained by the current search, if the time difference between the signal and the previous valley or the peak signal is less than a half preset period, the peak or trough of the current search is discarded. Signal, search again; or, for the peak or trough signal obtained from the current search, if the time difference between the signal and the previous peak or valley signal is less than a preset period, the peak or trough signal obtained by the current search is discarded and searched again.

As another technical solution, the present invention further provides an end point control device for a semiconductor etching process, comprising: a signal acquisition module for acquiring a real-time optical interference detection line; a wave crest search module for the optical Searching the peak signal and/or the valley signal in the interference detection line to obtain the etching cycle of the current process; the end point control module is used for etching according to the thickness of the etching required for the process and the single etching cycle. The thickness of the silicon wafer and the etching cycle of the current process are used to control the end point of the etching process.

Preferably, the device may further include: a pre-processing module, configured to perform pre-processing on the acquired optical interference detection spectrum, the pre-processing including filtering processing and/or delay processing, where the delay processing is used for ignoring An invalid signal that detects the beginning of the line for a period of time.

Preferably, the apparatus may further include: a verification module, configured to: discard the current search when the time difference between the peak and the valley signal obtained from the current search is less than a half preset period with the previous valley or peak signal The obtained peak or trough signal is notified to the peak valley search module to search again; or, for the peak or trough signal obtained by the current search, when the time difference between the peak or the valley signal is less than a preset period, the current search is discarded. The obtained peak or trough signal informs the peak trough search module to re-search.

Compared with the prior art, the present invention has the following advantages:

In order to meet the requirements of complex processes and to obtain the end time of the in-layer process, the present invention abandons the conventional optical emission spectrum signals, and uses an IEP detection line (Interferometry End Point), that is, an optical interference optical signal, It realizes the monitoring of the in-layer process etching process.

Secondly, the present invention uses the IEP to detect the end point of the process line grabbing process, The IEP detection line searches for the calculation process of the peak trough, and avoids the use of some complicated algorithms (for example, the Fourier transform of the time domain signal and the frequency domain signal, etc.), the calculation amount is relatively small, and not only the in-layer process can be realized. The control of the end point, and it is not easy to cause the delay of the process end time captured, more accurate.

Furthermore, the present invention can also remove the interference of the invalid signal or the noise signal through the pre-processing step and the verification step, thereby improving the accuracy of the end point control. DRAWINGS

1 is a schematic diagram showing changes in OES optical signal with process time in the prior art;

2 is a flow chart showing the steps of Embodiment 1 of an end point control method for a semiconductor etching process of the present invention;

Figure 3 is a schematic illustration of an example of an IEP line in a complex film process;

4 is a flow chart showing the steps of Embodiment 2 of an end point control method for a semiconductor etching process of the present invention;

5 is a flow chart showing the steps of a method for searching for a peak signal and/or a valley signal which can be used in an embodiment of the present invention;

6 is a flow chart showing another step of searching for a peak signal and/or a valley signal method that can be employed in an embodiment of the present invention;

Figure 7 is a block diagram showing the construction of an embodiment of an end point control device for a semiconductor etching process of the present invention. detailed description

The core of the present invention is to provide a plasma processing apparatus which is relatively simple in maintenance operation, thereby saving maintenance costs and significantly improving the efficiency of use of the plasma processing apparatus.

The present invention will be further described in detail with reference to the drawings and specific embodiments. Referring to FIG. 2, an embodiment 1 of an end point control method for a semiconductor etching process of the present invention is shown, which may specifically include the following steps:

Step 201: Acquire a real-time optical interference detection spectrum line;

Step 202: Search for a peak signal and/or a valley signal in the optical interference detection line to obtain an etching cycle of the current process;

Step 203: Perform end point control on the etching process according to the thickness of the etching required for the process, the thickness of the silicon wafer which can be etched by a single etching cycle, and the etching cycle of the current process.

Referring to Figure 3, a typical example of an IEP line in a complex film process is shown. The vertical axis of the IEP line is the line intensity; the horizontal axis is the process time in seconds. As can be seen from the figure, the periodicity of the IEP line is very uniform before and after the process time is 120 seconds. In simple terms, the time of 120 seconds of the process time is the moment of change between layers; the periodic fluctuations presented by the IEP line in the past characterize the process in a layer, followed by the periodic fluctuation characterization The process in another layer. SUMMARY OF THE INVENTION The present invention contemplates the use of uniform periodic fluctuations in a layer of the IEP line to effect endpoint control of the in-layer etching process.

The main technical principle adopted by the present invention is: According to the interference principle of light, it is known that the wavelength is

The emission spectrum of A, the thickness of the film etched in each cycle is: ^{D = ln} , where "is the refractive index of the emission spectrum through the film layer. On this basis, due to each process Before the start, the thickness of the wafer to be etched is known, and the etch cycle required for this etch can be calculated according to the parameters of the emission spectrum, and the IEP line characteristics shown in Fig. 3 are obtained. It can be known that it can well characterize the etch cycle fluctuation of this process, thus achieving the end point control of the process.

In the analysis of the characteristics of the real-time IEP line, the real-time time domain signal of the IEP line can be converted into a frequency domain signal, and then the number of cycles or cycles can be analyzed. However, this method requires continuous complex Fourier transform (Fast Fourier Transform) on the real-time signal in the process of the endpoint control, and the calculation amount is very large, which easily leads to the delay of the end signal; The present invention improves and uses The way to search for wave troughs (the specific process is detailed later), the amount of calculation is relatively small, can reduce the control The controller calculates the occupancy of resources and avoids delays.

From the schematic diagram of Fig. 3, we can see that in the time interval of process time from 40 seconds to 120 seconds, multiple peaks and troughs can be identified by the present invention, and each adjacent peak and trough can constitute a moment. The etch cycle, but the actual time value of each etch cycle may not be exactly equal. For example, in the time interval of process time from 40 seconds to 120 seconds, the etch cycle of the front end is about 6.5 seconds. The etching cycle of the terminal is about 6 seconds. Therefore, in practical applications, when performing end point control, the average value of the plurality of etch cycles that have been performed can be used, and the actual value of the latest etch cycle can be used.

Referring to FIG. 4, an embodiment 2 of an end point control method for a semiconductor etching process of the present invention is shown. Compared with the first embodiment, the embodiment 2 adds some preferred steps, which may specifically include the following steps:

Step 401: Acquire a real-time optical interference detection spectrum line;

Step 402: Perform pre-processing on the acquired optical interference detection spectral line, where the pre-processing includes filtering processing and/or delay processing (Delay), and the delay processing is used to ignore the invalid signal of the detection spectrum beginning for a period of time;

The filtering process can remove some noise signals and the like. There are many specific filtering methods. Preferably, the median filtering method, the arithmetic filtering method, the first-order lag filtering method, and the like can be used, and the present invention does not need to be limited. Since the etching is not actually started in the first part of the process, these optical signals do not correctly correct the etching process in the layer, so they need to be removed to obtain the peaks and valleys in the subsequent steps. The signal is correct.

Step 403: Search for a peak signal and/or a valley signal in the optical interference detection line. Step 404: Perform a test on the obtained peak signal and/or the valley signal, and obtain the peak signal and/or the valley signal according to the inspection. The etching cycle of the process;

Step 405: Perform end point control on the etching process according to the thickness of the etching required for the process, the thickness of the silicon wafer which can be etched by a single etching cycle, and the etching cycle of the current process.

Due to the search for peaks and valleys, it is possible to mistake the noise points of some spectral signals. In order to avoid this situation and to improve the recognition accuracy for the peak or trough signal, step 404 is preferably added in this embodiment. Step 404 may check all of the searched peak trough signals, or may only check for signals that partially satisfy certain conditions, and the present invention does not need to be limited thereto.

Specifically, step 404 can be tested in the following manner.

Mode 1: For the peak or trough signal obtained by the current search, if the time difference between the signal and the previous valley or peak signal is less than half a preset period, the peak or valley signal obtained by the current search is discarded and searched again.

Method 2: For the peak or trough signal obtained from the current search, if the time difference between the signal and the previous peak or valley signal is less than a preset period, the peak or valley signal obtained by the current search is discarded and searched again.

The above methods can be implemented alternatively or simultaneously. The preset period value may be set directly according to the empirical data, or may be set according to the real-time period calculation value. For example, the minimum etch period value of the line at the same wavelength of the same process is used as a measure, if the time difference between the searched peaks and valleys is less than half a minimum period (minimum half period), or between the peak and the peak (valley The time difference between the time and the valley is less than a minimum period, indicating that the searched signal points are incorrect and need to be searched again.

Referring to FIG. 5, a method for searching for a peak signal and/or a valley signal in the optical interference detecting spectrum, which may be used in the embodiment of the present invention, may specifically include the following steps:

Step 501: Determine a trend of the optical signal in the optical interference detection line; if the optical signal first shows an upward trend, perform steps 502-503-504; if the optical signal first exhibits a downward trend, execute Steps 505-506-507;

Step 502, searching for a peak signal;

Step 503, and then searching for the trough signal;

Step 504: Verify whether the searched peak signal and the valley signal meet the minimum half cycle. If yes, return to step 502 to perform the next peak search. If not, return to step 503 to search for the valley. signal. Step 505, searching for a valley signal;

Step 506, and then searching for a peak signal;

Step 507, it is checked whether the searched peak signal and the valley signal meet the minimum half period. If yes, return to step 505 to perform the next trough search; if not, return to step 506 to search for the peak again. signal.

Specifically, the change trend of the optical language signal in the optical interference detection line can be judged mainly by using the difference between the light intensity value of the continuous k point signals and the reference point light intensity value, that is, if there is a signal point ^ (0 is satisfied:

E(i + 1) _ E{i)≥ 0 E(i + 2)- E{i)≥ 0 E(i + k)- E{i)≥ 0 means that the IEP optical signal shows an upward trend , if there is a signal point O is satisfied:

E(i + 1) _ E{i) < 0 E(i + 2)- E{i) < 0 E(i + k)- E{i) < 0

It means that the IEP optical signal shows a downward trend.

The core and key of this step is the determination of the parameters. The value of the parameters is closely related to the frequency of the signal. If the frequency of the sample is larger, the value of the parameter can be increased accordingly.

Specifically, for the search and determination of the peaks and troughs, the difference between the light intensity value of the left and right continuous points of the target point and the light intensity value of the target point can be used. E.g,

For a search for a peak in the current signal point, if there is a signal point that satisfies the following equation, then the signal point (0 is a peak of the optical signal:

E{i) - E(i -1)>0 E{i) - E(i -2)>0 E{i) - E(i -m)≥0

E(i)-E(i + l)≥0 E(i)-E(i + 2)≥0 E(i)-E(i + m)≥0 For searching for the trough in the current signal point, Then, if there is a signal point that satisfies the following formula, then the signal point O is a trough of the optical language signal:

E{i) - E(i -1)<0 E{i) - E(i -2)<0 E{i) - E(i -m)≤0

E(i)-E(i + l)≤0 E(i)-E(i + 2)≤0 E(i)-E(i + m)≤0

In the formula, the parameter is the number of judgment conditions of the peak wave trough signal, and the larger the ^, the peak or trough letter The more true the number.

Referring to FIG. 6, another method for searching for a peak signal and/or a valley signal in the optical interference detecting line which can be used in the embodiment of the present invention is shown. The flow shown in FIG. 6 and the flow shown in FIG. The difference is that the flow of Figure 6 does not need to determine the signal trend, but to start the search directly. Specifically, it can include:

Step 601, select a search peak or trough signal; if the search for a peak is selected, step 602 is performed, if the search trough is selected, step 606 is performed;

Step 602, searching for a peak signal;

Step 603, searching for a next peak signal;

Step 604, it is checked whether the two adjacent peaks satisfy the minimum period. If yes, step 603 is performed to search for the next peak signal. If not, step 605 is performed to search for the current peak signal until it meets the condition. Then, step 603 is performed to search for the next peak signal.

Step 606, searching for a valley signal;

Step 607, searching for the next trough signal;

Step 608, it is checked whether the two adjacent valleys satisfy the minimum period. If yes, step 607 is performed to search for the next trough signal; if not, step 609 is performed to re-search the current trough signal until it meets the condition. Then, step 607 is performed to search for the next trough signal.

The above-described flow charts shown in Figs. 5 and 6 are merely examples of the search for peak wave trough signals of the present invention. In fact, there are many possible solutions, and the present invention is not described herein in detail. For example, the search process of the peak and trough signals in the flow shown in Figure 6 can be performed without any alternative; for example, for the optical signal in the beginning of the spectrum, it is judged whether it is a peak signal or not. Whether it is a trough signal, etc. After determining a signal, whether it is a peak or a trough, the subsequent judgment process is determined, because the peaks and valleys must be spaced apart.

A brief description of the specific control process that may be employed by the present invention is provided below.

Control method 1

Step a, according to the etching cycle of the current process, real-time calculation is up to the current time point t, this time The number of cycles through which the etching process passes;

For example, the etching cycle of the process is T, then, for the current time point t, the number of cycles elapsed by the etching process is Count=t/T.

Step b: obtaining the number of cycles required for the process end point according to the thickness of the etching required for the process and the thickness of the silicon wafer which can be etched by a single etching cycle;

Step c: By comparing the above two cycle numbers, it is known whether the current time point t reaches the end point of the process, and then performs corresponding control.

Specifically, since the time values of each etch cycle are not absolutely the same in the actual process, the number of cycles of the current time point t can be calculated in real time according to the average of the plurality of etch cycles that have been calculated. Of course, the actual number of etch cycles that have been calculated may be counted by the actual value. For the latest one etch cycle, the time value of the current etch cycle may be used for calculation. Since there are many specific calculation methods, the present invention is not detailed here.

Control method 2

Step a. Calculate the thickness of the etched silicon wafer at the current time point t in real time according to the etching period of the current process and the thickness of the silicon wafer which can be etched by the single etching period;

For the emission spectrum of wavelength A, the thickness of the film etched away in each period is: 0 = λΙΐη, where "is the refractive index of the emission spectrum through the film layer. Then, the current time point _t , The thickness of the silicon wafer that has been etched is: h = Count * A/2n, where Count = t/T.

Step b: By comparing the calculated thickness h with the thickness H of the etching required for the process, it is known whether the current time point t reaches the process end point, and then performs corresponding control.

Control method 3

Step a, obtaining the number of cycles required for the process end point according to the thickness of the etching required for the process and the thickness of the silicon wafer which can be etched by a single etching cycle; and further, according to the etching cycle of the process, The end point prediction time T of the secondary process;

Step b: By comparing the current time point t with the end point prediction time T, it is known whether the current time point t reaches the process end point, and then performs corresponding control. The control principles of control modes 1, 2, and 3 are basically similar, and the similarities are not repeated here.

Referring to Figure 7, an embodiment of an end point control device for a semiconductor etch process of the present invention is shown. The endpoint control device of the semiconductor etching process provided by this embodiment includes the following modules:

a signal acquisition module 701, configured to acquire a real-time optical interference detection line;

The peak valley search module 702 is configured to search for a peak signal and/or a valley signal in the optical interference detection line to obtain an etching cycle of the current process;

The end point control module 703 is configured to perform end point control on the etching process according to the thickness of the etching required for the process, the thickness of the silicon wafer which can be etched by a single etching period, and the etching period of the current process.

Preferably, the embodiment shown in FIG. 7 may further include: a pre-processing module 704, configured to perform pre-processing on the acquired optical interference detection spectral line, where the pre-processing includes filtering processing and/or delay processing, and the delay processing Used to ignore invalid signals that have started detecting the line for a period of time. The preprocessed spectral line signal is then output to a peak valley search module 702 for searching for peaks and valleys.

Preferably, the embodiment shown in FIG. 7 further includes: an inspection module 705, configured to check the peak trough signal obtained by the peak valley search module 702 to prevent the noise signal from being erroneously confirmed as a peak or trough signal.

Specifically, it can be tested in the following ways:

For the peak or trough signal obtained by the current search, when the time difference between the signal and the previous valley or peak signal is less than half a preset period, the peak or trough signal obtained by the current search is discarded, and the peak valley search module is re-searched;

Or, for the peak or trough signal obtained by the current search, when the time difference between the signal and the previous peak or trough signal is less than a preset period, the peak or trough signal obtained by the current search is discarded, and the peak valley search module is notified to search again.

The various embodiments in the present specification are described in a progressive manner, and each embodiment focuses on differences from other embodiments, and the same similar parts between the various embodiments can be referred to each other. In addition, since the device embodiment shown in FIG. 7 can be correspondingly applied to the foregoing method embodiment Medium, so the description is relatively simple. For details, please refer to the description in the corresponding section earlier in this manual. The above description of the method and apparatus for controlling the end point of a semiconductor etching process provided by the present invention is described above, and the description of the above embodiments is merely for helping to understand the method of the present invention and its core idea; and, for a person of ordinary skill in the art, The present invention is not limited by the scope of the present invention.

Claims

Request

A method for controlling an end point of a semiconductor etching process, comprising the steps of: acquiring a real-time optical interference detecting line;

Searching for the peak signal and/or the valley signal in the optical interference detection line to obtain an etching cycle of the current process;

According to the thickness of the etching required for the process, the thickness of the silicon wafer which can be etched by a single etching cycle, and the etching cycle of the current process, the end point control of the etching process is performed.

2. The method of claim 1 wherein the endpoint control of the etching process is accomplished in the following manner:

According to the etching cycle of the process, the number of cycles elapsed by the etching process is calculated in real time until the current time point t;

According to the thickness of the etching required for the process and the thickness of the silicon wafer which can be etched by a single etching cycle, the number of cycles required for the process end point is obtained;

By comparing the above two cycle numbers, it is known whether the current time point t reaches the process end point, and then performs corresponding control.

3. The method of claim 1 wherein the endpoint control of the etching process is accomplished in the following manner:

Calculating the thickness of the etched silicon wafer at the current time point t in real time according to the etch cycle of the process and the thickness of the silicon wafer that can be etched by a single etch cycle;

By comparing the calculated thickness with the thickness of the etching required for the current process, it is known whether the current time point t reaches the end point of the process, and then the corresponding control is performed.

4. The method of claim 1 wherein the endpoint control of the etching process is accomplished in the following manner:

According to the thickness of the etching required for the process and the thickness of the silicon wafer which can be etched by a single etching cycle, the number of cycles required for the process end point is obtained; and further, according to the etching cycle of the process, the process is obtained. End point prediction time;

By comparing the current time point t with the end point prediction time, it is known whether the current time point t reaches the end of the process, and then the corresponding control is performed.

5. The method of claim 1, further comprising:

Pre-processing the acquired optical interference detection line, the pre-processing including filtering processing and

/ or delay processing, which is used to ignore the invalid signal of the detection line beginning for a period of time.

6. The method of claim 5, wherein the peak signal and/or the valley signal are searched for in the optical interference detection line by:

Determining the trend of the optical signal in the optical interference detection line;

If the optical signal first shows an upward trend, the search process of the peak-to-valley phase starting with the peak search is initiated;

If the spectral signal first exhibits a downward trend, a search process for the peak-to-valley phase beginning with the trough search is initiated.

7. The method of claim 5, wherein the peak signal and/or the valley signal are searched for in the optical interference detection line by:

Search for crest signals directly; and / or

Search for trough signals directly.

8. The method of claim 1, further comprising:

For the peak or trough signal obtained by the current search, if the time difference between the signal and the previous valley or peak signal is less than half a preset period, the peak or trough signal obtained by the current search is discarded, and the search is repeated;

For the peak or trough signal obtained by the current search, if the time difference between the signal and the previous peak or trough signal is less than a preset period, the peak or trough signal obtained by the current search is discarded and searched again.

A terminal control device for a semiconductor etching process, comprising: a signal acquisition module, configured to acquire a real-time optical interference detection line; a peak wave trough search module, configured to search for a peak signal and/or a valley signal in the optical interference detection line, thereby obtaining an etching cycle of the current process;

The end point control module is used for controlling the end point of the etching process according to the thickness of the etching required for the process, the thickness of the silicon wafer which can be etched by the single etching period, and the etching period of the current process.

10. The device according to claim 9, further comprising:

And a pre-processing module, configured to perform pre-processing on the acquired optical interference detection line, the pre-processing including filtering processing and/or delay processing, which is used to ignore the invalid signal at the beginning of the detection line.

11. The apparatus according to claim 9, further comprising: a verification module, configured to:: a peak or a trough signal obtained for the current search, when a time difference from the previous trough or crest signal is less than half a pre- When setting the period, discard the peak or trough signal obtained by the current search, and notify the peak valley search module to search again; or

For the peak or trough signal obtained by the current search, when the time difference between the signal and the previous peak or trough signal is less than a preset period, the peak or trough signal obtained by the current search is discarded, and the peak valley search module is re-searched.