TW201440155A - Endpoint detection device and method of plasma treatment process - Google Patents

Abstract

The invention discloses an endpoint detection method of a plasma treatment process. The plasma treatment process comprises a plurality of periodical plasma treatment steps. The endpoint detection device includes collecting real-time optical signal strength with a specific wavelength in the plasma treatment process at regular intervals to obtain a plurality of real-time optical signal strength sampling values and establishing a real-time optical signal strength spectral line with periodicity; defining a flat area inside every period of the real-time optical signal strength spectral line; extracting an optical signal strength characteristic value in every flat area; establishing an optical signal strength characteristic spectral line according to the optical signal strength characteristic values; and determining an endpoint of the plasma treatment process according to the optical signal strength characteristic spectral line. The invention also provides an endpoint detection device of the plasma treatment process. The endpoint detection device and the endpoint detection method of the plasma treatment process can effectively improve the accuracy of the endpoint detection of a plasma periodical disturbance process.

Description

End point detecting device and method for plasma processing process

The present invention relates to the field of semiconductor manufacturing technology, and in particular, to an end point detecting device and method for a plasma processing process.

In recent years, with the development of semiconductor manufacturing processes, the integration and performance requirements of components are becoming higher and higher, and Plasma Technology plays an important role in the field of semiconductor manufacturing. Plasma technology is applied to many semiconductor processes by plasma generated by excitation of process gases, such as deposition processes (such as chemical vapor deposition), etching processes (such as dry etching), and the like. For plasma processing, its accuracy is directly related to the feature size of the component. As the feature size of semiconductor devices shrinks and the number and complexity of plasma processing steps used in semiconductor manufacturing processes increase rapidly, the requirements for plasma processing process control become more stringent, requiring real-time monitoring To control the critical stages of the process.

Taking the plasma etching process as an example, in the plasma etching process, a key problem is that after the etched dielectric layer is etched away, the plasma etching should be stopped in time to prevent the underlying dielectric layer from being damaged by plasma etching. , causing the device to fail. Therefore, it is increasingly important to accurately determine the end point of the plasma etch process to avoid component failure due to insufficient or excessive etch. In the prior art, plasma etch end point detection is usually performed by optical emission spectroscopy (OES). The OES technology is based on the on-line spectrum detection equipment to detect the spectrum emitted by the plasma in real time. Due to the etch to different material layers, the spectrum will change significantly, especially when the arrival is the end point of the etching, due to the conversion of the etched material, the gas phase Both the composition and the film being etched undergo chemical changes that are manifested by changes in the intensity of the OES spectral signal. Therefore, by continuously monitoring the plasma emission, the OES endpoint detection method can be used to detect this change and use it to Determine when the film is completely removed. For example, when the OES signal falls below a predetermined threshold level, this transition is utilized to trigger an "end point." Therefore, by detecting the emission line intensity value of the reactant or product when etching a substance to a different layer in the etching process, the etching end point can be judged. For example, U.S. Patent No. 5,565,114 discloses a method of detecting an end point by OES technique in a plasma process by first calculating the sum of the sums of the intensity spectra of the plasma light, and then calculating the difference or ratio of the mean values to determine whether the etching reaches the termination point. It can be seen that the process of the single etching step process or the limited separation etching step of the process stability can be well realized by the OES technology.

Nowadays, deep reactive ion etching of wafers to form high aspect ratio structures (such as germanium via technology) is gaining more and more attention and research. Deep reactive ion etching is usually carried out by the Bosch process. The Bosch process is a process in which the semiconductor wafer is etched deep in the vertical direction by periodically repeating the plasma etching process and the plasma deposition process. The Bosch process mainly includes the following steps: (1) an etching step, usually a chemical reaction ion etching using a mixed gas containing SF ₆ ; (2) a polymer deposition passivation step, usually using a mixed gas containing C ₄ H ₈ in the inner side of the hole Forming the fluorocarbon polymer layer so that the chemical reaction ion etching in the etching process of the next cycle, the SF ₆ gas does not etch the polymer of the sidewall or the etching rate is very slow; the etching step and the deposition step are alternately cycled until Deep hole etching is completed. Since the Bosch process uses alternating repeating isotropic etching and polymer deposition processes, and the plasma conditions (such as process gas type, pressure, RF power, etc.) used in the etching and deposition steps are not the same, the Bosch process is performed. The plasma emission spectra of the etching step and the deposition step in the process are significantly different. As shown in Figure 1, the application of conventional OES technology to Bosch processes with fast and periodic plasma disturbance characteristics leads to periodic end-point trajectories, which are prone to misjudgment of plasma emission intensity changes, so that it is impossible to accurately detect the end point. .

In order to solve the above technical problems, U.S. Patent No. 7,101,805 discloses a method of establishing an end point during an alternate cycle etching process or a time division multiplexing process. It uses known light emission spectrometry (OES) to detect changes in plasma emission intensity, and uses an envelope follower algorithm to extract amplitude information from complex waveforms of plasma emission intensity. The envelope follower algorithm uses multiple peak detection algorithms and is sequentially reset according to the cyclic method. That is to say, in this patent, the emission peak is used to form the envelope, and then according to the envelope trajectory. The time at which the endpoint is generated is constructed to determine the endpoint. However, in practice, since the peak is generally generated by the RF source being emitted at the beginning of the process step, it is also the most unstable region of the plasma, so it is prone to deviation, and the envelope-to-end point formed by it Detection is generally not sensitive. In addition, the data acquisition frequency is generally fixed, but in the actual sampling process, the synchronization of the plasma power, gas and sampling time of the terminal detection will be different in each cycle, and it is likely that a delay will occur, resulting in a collection point. The position will not coincide with the maximum value. If the delay time is different, the data point to the left of the peak may be collected at different sampling times, and the data point to the right of the peak or peak value, because the relative value of the data values on both sides of the peak is relatively large, so that the envelope formed Line jitter is very large. Therefore, the accuracy of the end point detection using the envelope formed by the peak is not good, especially when the etching area is small, it cannot be used for the end point detection.

Therefore, how to realize an endpoint detection method with high accuracy and flexibility to accurately find the end point of the plasma treatment process with alternating cycle steps becomes a difficult problem in the semiconductor manufacturing process using plasma technology.

The main object of the present invention is to overcome the deficiencies of the prior art and to provide an end point detecting device and method for a plasma processing process to improve the sensitivity and accuracy of the end point detection of the alternating cycle plasma processing process by the OES method.

In order to achieve the above object, the present invention provides an end point detecting method for a plasma processing process, the plasma processing process comprising a plurality of periodic plasma processing steps, the end point detecting method comprising: collecting the plasma at certain time intervals Instantaneous optical signal strength at a particular wavelength during the body processing process to obtain a plurality of instantaneous optical signal strength samples and to establish a periodic instantaneous optical signal intensity line, the instantaneous optical signal strength reacting with the plasma processing process a concentration of the component or a concentration of the product component; defining a gradual zone in each of the periods of the instantaneous optical signal intensity line, the gradual zone having at least one of the instantaneous optical signal intensity samples; Extracting, as an optical signal intensity characteristic value, an instantaneous optical signal strength sample value in the gradual region; establishing an optical signal strength characteristic line according to the optical signal strength characteristic value; and determining, according to the optical signal intensity characteristic line The end point of the plasma treatment process.

Preferably, the gradual zone has at least two of the instant optical signal strength samples.

Preferably, the step of defining a gradual region in each period of the instantaneous optical signal intensity line includes defining, as the gradual, a region in which the variation of the instantaneous optical signal strength sample value is less than a reference value in a certain period of time. a region, wherein the reference value ranges from 0.1% to 10% of a maximum value of the instantaneous optical signal strength sample value in the period.

Preferably, the step of defining a gradual region in each period of the instantaneous optical signal intensity line comprises sampling the instantaneous optical signal strength sample value within a predetermined range and sampling the instantaneous optical signal intensity for a certain period of time A region in which the amount of change in value is less than the reference value is defined as the gradual region, wherein the reference value ranges from 0.1% to 10% of the maximum value of the instantaneous optical signal strength sample value in the period.

Preferably, the step of extracting an optical signal strength characteristic value in the instantaneous optical signal strength of each of the gradual regions comprises: determining a number of instantaneous optical signal strength sampling values in the gradual region; and when the instant optical signal When the number of the intensity sampling values is 2N-1, the Nth instantaneous optical signal strength sample value is extracted as the optical signal strength characteristic value; when the number of the instant optical signal strength sampling values is 2N, the Nth is extracted. Or N+1th instantaneous optical signal strength sample values as the optical signal strength characteristic values, where N is a positive integer greater than one.

Preferably, the step of determining an end point of the plasma processing process according to the optical signal intensity characteristic line comprises: determining a feature value inflection point according to the optical signal intensity characteristic line; and determining the plasma according to the characteristic value inflection point The end point of the body treatment process.

Preferably, each of said plasma processing steps includes an etching step and a deposition step.

The present invention also provides an end point detecting device for a plasma processing process, wherein the plasma processing process includes a plurality of periodic plasma processing steps, the end point detecting device comprising: a signal acquisition module for using a time interval Acquiring the instantaneous optical signal intensity during the plasma processing process to obtain a plurality of instantaneous optical signal intensity sampling values and establishing a periodic instantaneous optical signal intensity spectral line, the instantaneous optical signal strength and the plasma processing process Corresponding to a component concentration or a product component concentration; a gradual zone defining module coupled to the signal acquisition module for defining each cycle of the instantaneous optical signal intensity line a gradual zone having at least one of the instant optical signal strength samples; the eigenvalue extraction module, and the gradual zone definition module for instantaneous optical signal strength in each of the gradual zones Extracting one of the sampled values as an optical signal intensity characteristic value; a characteristic line establishing module connected to the characteristic value extracting module for establishing an optical signal intensity characteristic line according to the optical signal intensity characteristic value; and an end point The determining module is connected to the characteristic value spectrum establishing module for determining an end point of the plasma processing process according to the optical signal intensity characteristic line.

Preferably, the gradual zone has at least two of the instant optical signal strength samples.

Preferably, the grading area defining module defines, according to the change of the instantaneous optical signal strength, an area in which the variation of the instantaneous optical signal strength sampling value is less than a reference value in a certain period of time as the gradual area, where The reference value ranges from 0.1% to 10% of the maximum value of the instantaneous optical signal strength sample value in the period.

Preferably, the tempering zone definition module sets the instantaneous optical signal strength sample value within a predetermined range according to the change of the instantaneous optical signal strength and the instantaneous optical signal strength, and the instant light is within a certain time period. A region in which the amount of change in the signal strength sample value is smaller than the reference value is defined as the gradation region, wherein the reference value ranges from 0.1% to 10% of the maximum value of the instantaneous light signal intensity sample value in the period.

Preferably, the feature value extraction module includes a determination sub-module and an extraction sub-module, and the determination sub-module is configured to determine the number of instantaneous optical signal strength sampling values in the gradual area; the extraction sub-module The group is connected to the determining sub-module, and when the number of the instantaneous optical signal strength sampling values is 2N-1, extracting the Nth instantaneous optical signal strength sampling value as the optical signal strength characteristic value; When the number of the instantaneous optical signal strength sample values is 2N, the Nth or N+1th instantaneous optical signal strength sample value is extracted as the optical signal strength characteristic value, where N is a positive integer greater than 1.

Preferably, the endpoint determining module further includes a feature value inflection point search submodule and an end point determining submodule, and the feature value inflection point search submodule determines a feature value inflection point according to the optical signal intensity characteristic line; The endpoint determining sub-module is coupled to the feature value inflection point search sub-module, and determining an end point of the plasma processing process according to the feature value inflection point.

Preferably, each of the plasma processing steps includes an etching step and a a deposition step.

The invention has the beneficial effects of using a pattern recognition method to form a smooth optical signal intensity-time characteristic line by defining a gradual area in the instantaneous optical signal intensity line and extracting the optical signal intensity characteristic value in the gradual area. Solving the problem of misjudgment of the endpoint judgment caused by the rapid and periodic disturbance of the plasma, and effectively improving the defect that the maximum value forming envelope is insensitive to the endpoint determination and the envelope jitter is easy to occur, resulting in inaccurate endpoint detection in the prior art. . In addition, in the present invention, even if a delay occurs in the extraction of the optical signal intensity characteristic value, the formed envelope is ensured to be smooth, thereby effectively improving the end point detection capability and the detection flexibility.

Steps 201, 202, 203, 204, 205‧‧

701‧‧‧Signal acquisition module

702‧‧‧ Flat Zone Definition Module

703‧‧‧Characteristic value extraction module

704‧‧‧Characteristic line building module

705‧‧‧ Endpoint Determination Module

Figure 1 is a schematic diagram showing the OES optical signal intensity obtained in the prior Bosch process as a function of process time.

2 is a flow chart showing the steps of an end point detecting method of a plasma processing process according to an embodiment of the present invention.

3 is a schematic view showing an instantaneous light signal intensity spectrum line in a plasma processing process according to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing the comparison of the optical signal intensity characteristic lines of the reactants in the prior art using the peak formed envelope and the plasma processing process of the present invention.

Figure 5 is a schematic illustration of the optical signal intensity characteristic line of the etched product when the etched area of the plasma processing process is the wafer area.

Figure 6 is a schematic illustration of the optical signal intensity characteristic line of the etched product when the etched area of the plasma processing process is 5% of the wafer area.

FIG. 7 is a block diagram showing an end point detecting device of a plasma processing process according to an embodiment of the present invention.

In order to make the content of the present invention clearer and easier to understand, the contents of the present invention will be further described below in conjunction with the accompanying drawings. Of course, the invention is not limited to the specific embodiment, and general replacements well known to those skilled in the art are also encompassed within the scope of the invention.

It is known from the background art that in a plasma processing process having a periodic processing step, the method of extracting the peak forming envelope to detect the end point of the plasma process does not accurately detect the end point. To this end, the present invention proposes an optimized plasma processing process endpoint detection method to address the deficiencies of the prior art.

Please refer to FIG. 2, which illustrates an end point detecting method of a plasma processing process of the present invention, the plasma processing process including a plurality of periodic plasma processing steps. Specifically, the method may include the following steps: Step 201: Acquire real-time optical signal intensity of a specific wavelength during a plasma processing process at a certain time interval to obtain a plurality of instantaneous optical signal strength sampling values and establish a periodic optical signal intensity line with periodicity Where the instantaneous light signal intensity corresponds to the reactant component concentration or the product component concentration of the plasma treatment process, those skilled in the art can select an appropriate specific wavelength of the instantaneous light signal according to the type of the wafer and the type of the process gas, and Get instant optical signal strength at a specific wavelength.

Step 202: Define a gradual zone in each period of the instant optical signal intensity line, the gradual zone having at least one of the instant optical signal strength samples.

Step 203: Extract one of the instantaneous optical signal strength sample values in each of the gradual regions as an optical signal strength feature value.

Step 204: Establish an optical signal intensity characteristic line according to the optical signal strength characteristic value.

Step 205: Determine an end point of the plasma processing process according to the optical signal intensity characteristic line.

Referring to FIG. 3, there is shown a schematic diagram of the optical signal intensity variation of plasma in a plasma processing process according to an embodiment of the present invention, that is, a schematic diagram of an instantaneous optical signal intensity spectrum of a specific wavelength. The plasma processing process of the present invention includes a plurality of periodic plasma processing steps, and each plasma processing step can include a plurality of different steps. In the present embodiment, each of the plasma processing steps includes an etching step and a deposition step, and the plasma processing is a Bosch process, and etching is performed by periodically alternately repeating the plasma etching step and the plasma deposition step. Of course, in other embodiments, each plasma processing step may also include an etching step, a deposition step, a transition step or a cleaning step, etc., and the invention is not limited thereto. this.

The technical principle of the present invention is to first acquire the instantaneous optical signal intensity at a certain time interval to obtain a plurality of instantaneous optical signal strength sampling values and establish an instantaneous optical signal intensity spectral line according to the instantaneous optical signal strength sampling values, as shown in FIG. In this embodiment, the time interval of the acquisition is 200 ms, and each point in FIG. 3 is the instantaneous optical signal strength sample value. Since the plasma processing process has a plurality of periodic processing steps, the spectral lines formed by the acquired instantaneous optical signal intensity sampling values are also periodically periodic. As can be seen from FIG. 3, the periodicity of the instantaneous optical signal intensity spectral lines Very uniform. Then, a gradual zone is defined in each period of the optical signal intensity line, and at least one instantaneous optical signal intensity sample value is included in the gradual zone, and the fluctuation of the sampled value of the optical signal intensity collected at the time of the process time of 165 seconds is small. , it is considered to be in a gentle zone. The present invention can employ different methods to define a gradual zone, such as a time delay after the start of the cycle, or a trend of the sampled value according to the intensity of the optical signal. When there is only one instantaneous optical signal strength sample value in the gradual zone, jitter is easy to occur. In order to improve this jitter phenomenon, at least two instantaneous optical signal strength samples may be included in the gradual zone to provide more selectivity and accuracy. . In this embodiment, according to the change of the sampling value of the instantaneous optical signal strength, a portion in which the variation of the instantaneous optical signal strength sampling value is smaller than the reference value is defined as a gradual region within a certain period of time (eg, three acquisition time intervals). The area of the line corresponding to the 159.4th to 159.8th seconds in Figure 3. Certainly, in other embodiments, a period of the instantaneous optical signal strength spectrum may have a plurality of optical signal intensity sample values that are gentle, that is, a change in the instantaneous optical signal strength sample value meets the required region, and may be further limited. The size of the instantaneous optical signal strength sample value is defined as a gradual region in which the optical signal strength sample value is within a predetermined range and the amount of change of the optical signal strength sample value is less than the reference value within a certain period of time. Preferably, the reference value ranges from 0.1% to 10% of the maximum value of the instantaneous optical signal strength sample value in the period, wherein the sampled value of the highest point of the instantaneous optical signal intensity line in the period can be used as the sampling value The maximum value of the instantaneous optical signal strength sample value for this period. Then, one of the instantaneous optical signal intensity samples of each gradual zone is extracted as an optical signal strength eigenvalue, and the eigenvalues are used to form an optical signal strength characteristic line. Since the extracted optical signal intensity characteristic values are all located in the gradual region, they are relatively stable and are not easy to be deviated, and the characteristic lines formed by them are more sensitive to the end point detection.

Next, the plasma processing process is determined based on the formed feature value lines. Figure 4 is a schematic diagram comparing the optical signal intensity characteristic line 2 of the reactants in the prior art using the peak formed envelope 1 and the plasma treatment process of the present invention. As shown in FIG. 4, for the use of the peak to form the envelope 1, since the stability of the peak is poor, the sensitivity to the end point is low, and it is basically impossible to determine the end point. The spectral line 2 formed by the instantaneous light signal intensity characteristic value of the present invention can clearly find the characteristic value inflection point, that is, the characteristic value inflection point, and the characteristic line 2 of the reactant rapidly rises as it approaches the inflection point of the characteristic value. Therefore, the inflection point of the feature value can be determined according to the characteristic line, and the end point of the plasma processing process can be further obtained according to the inflection point of the feature value.

Further, in order to extract the appropriate instantaneous light intensity characteristic value in the gradual area, the data point of the intermediate position of the instantaneous optical signal intensity sampling value is extracted as light in the gradual area of each period of the instant optical signal line. Signal strength eigenvalue. In detail, firstly, the number of samples of the instantaneous optical signal intensity in the gradual area is determined. When the number of the instantaneous optical signal intensity samples is an odd number, the intermediate instantaneous optical signal intensity sample value is extracted as the optical signal strength characteristic value; When the number of signal strength samples is an even number, one of the two instantaneous optical signal intensity samples in the middle is extracted as the optical signal strength characteristic value. This is because the instantaneous optical signal strength sampling value extraction may have a decimation delay and the time of each delay is inconsistent. If the flat region has multiple instantaneous optical signal strength sampling values, the optical signal at the edge of the gradual region is extracted. The intensity sampling value data point is easy to extract the optical signal intensity sampling value outside the gradual area due to the delay, and the optical signal intensity sampling value varies greatly in this area, so the characteristic line formed by it will be more Sawtooth, if the intensity change of these serrations is close to the intensity change of the inflection point of the feature value, the eigenvalue inflection point misjudgment may easily occur and eventually affect the end point judgment. In the detection method of the present invention, the instantaneous optical signal strength sample value in the middle of the tempering zone is extracted as the optical signal strength eigenvalue, and even if the delay occurs in advance extraction or delayed extraction, the extracted optical signal strength eigenvalue is still gentle. In the area, the characteristic line formed is still very smooth, so that it is easy to find the inflection point of the characteristic value of the optical signal intensity that changes, especially when the etching area is small and the signal intensity changes are weak, it can still be effectively judged. , thereby improving the ability of endpoint detection. 5 and 6 are schematic diagrams showing the optical signal intensity characteristic lines of the etching product when the etching area of the Bosch process is the same as the wafer area, and the etching area is 5% of the wafer area, respectively. As can be seen from the figure, when the inflection point of the characteristic value is approached, the characteristic line corresponding to the etching product is significantly decreased, indicating that the concentration of the etching product is lowered. Even if the etching area in Figure 6 is reduced to a certain extent, the characteristic spectrum When the change of the line is weak, the inflection point of the feature value can still be found.

It should be noted that after the optical signal intensity characteristic line is formed, various methods can be used to determine the inflection point of the feature value, such as threshold crossing detection or derivative processing. For details, reference may be made to the etching end point judgment mode of the existing plasma etching process, which is Those skilled in the art are well known and will not be described herein.

According to the inflection point of the characteristic value of the optical signal strength, the end point of the plasma processing process can be determined. Generally, the end point can be the instantaneous light signal intensity sampling value in the period of the inversion point of the characteristic value in the instantaneous light intensity spectrum. The time point, that is, the time point at the end of the plasma processing step, the present invention is not limited thereto.

In summary, the end point detection method of the plasma processing process of the present invention can not only solve the problem of misjudgment of the process end point determination for rapid and periodic disturbance of the plasma, but also effectively improve the flexibility of the end point detection.

Next, please refer to FIG. 7, which illustrates an embodiment of an end point detecting device for a plasma processing process of the present invention. The end point detecting device includes a signal collecting module 701 for collecting a plasma processing process at intervals of time. The instantaneous optical signal strength of a particular wavelength is obtained to obtain a plurality of instantaneous optical signal strength samples and to establish a periodic optical signal intensity line with periodicity.

The grading area defining module 702 is connected to the signal collecting module 701, and is configured to define a gradual area in each period of the instant optical signal intensity spectrum line, each tempering area having at least one instantaneous optical signal strength sampling value; The ambiguous area definition module 702 may define, according to the change of the instantaneous optical signal strength sampling value, an area in which the change amount of the instantaneous optical signal strength sampling value is less than a reference value in a certain period of time as the gradual area; or The instantaneous optical signal strength sample value and the instantaneous optical signal strength sample value change, the instantaneous optical signal strength sample value is within a predetermined range and the instantaneous optical signal strength sample value relative time is within a certain period of time The area where the amount of change is smaller than the reference value is defined as the gentle area. The reference value ranges from 0.1% to 10% of the maximum value of the instantaneous optical signal strength sample value in the period.

The feature value extraction module 703 is connected to the gradation area definition module 702 for extracting one of the instantaneous optical signal strength sample values in each gradation area as the optical signal strength feature value. Preferably, the feature value extraction module 703 further includes a judgment sub-module and an extraction sub-module, and determines The sub-module is used for judging the number of instantaneous optical signal strength sampling values in the gradual area; the extraction sub-module is connected to the judging sub-module, and when the number of the instant optical signal strength sampling values is 2N-1, the Nth instant is extracted. The optical signal strength sample value is used as the optical signal strength characteristic value; when the instantaneous optical signal strength sample value is 2N, the Nth or N+1th instant optical signal intensity sample value is extracted as the optical signal strength characteristic value, where N is A positive integer greater than one.

The characteristic line establishing module 704 is connected to the feature value extracting module 703 for establishing an optical signal intensity characteristic line according to the optical signal intensity characteristic value.

The endpoint determination module 705 is coupled to the feature line setup module 704 to determine the end of the plasma processing process based on the optical signal intensity profile.

In a preferred embodiment of the present invention, the endpoint determining module 705 may further include a feature value inflection point search submodule and an end point determining submodule, and the feature value inflection point search submodule determines the feature value according to the optical signal intensity characteristic line. The changed feature value inflection point; the end point determining sub-module is connected to the feature value inflection point search sub-module, and the end point of the plasma processing process is determined according to the feature value inflection point.

The endpoint detecting device shown in FIG. 7 can be implemented by software, firmware, hardware, or a combination thereof, and is not limited herein. Since the end point detecting device corresponds to the aforementioned end point detecting method, the description is relatively simple, and the details of the corresponding parts in the foregoing description of the present specification can be referred to.

In summary, the present invention makes full use of the pattern recognition method, and forms a characteristic line by defining a gradual area in the acquired instantaneous optical signal intensity line and extracting the feature value therefrom, thereby forming a smooth optical signal intensity-time curve. Improves the accuracy of endpoint detection in plasma periodic disturbances. Further, the present invention effectively improves the problem of inaccurate extraction of the feature values due to the signal strength acquisition delay by extracting the feature values in the middle of the gradual zone, and has high flexibility and practicability.

The present invention has been described in terms of the preferred embodiments of the present invention, and the present invention is intended to be illustrative only, and is not intended to limit the scope of the invention. In the case of a number of changes and refinements, the scope of protection claimed in the present invention shall be as defined in the claims.

Steps 201, 202, 203, 204, 205‧‧

Claims (14)

An end point detecting method for a plasma processing process, the plasma processing process comprising a plurality of periodic plasma processing steps, the end point detecting method comprising: collecting a specific wavelength of the plasma processing process at intervals of time Instant optical signal strength to obtain a plurality of instantaneous optical signal strength samples and to establish a periodic instantaneous optical signal intensity line, the instantaneous optical signal strength and the reactant component concentration or product composition of the plasma processing process Corresponding to a concentration; defining a gradual zone in each period of the instant optical signal intensity line, the gradual zone having at least one of the instant optical signal strength samples; and instant light in each of the gradual zones Extracting one of the signal strength sample values as an optical signal strength characteristic value; establishing an optical signal strength characteristic line according to the optical signal strength characteristic value; and determining an end point of the plasma processing process according to the optical signal intensity characteristic line. The endpoint detection method of a plasma processing process according to claim 1, wherein said gentle region has at least two of said instantaneous optical signal intensity samples. The endpoint detection method of a plasma processing process according to claim 2, wherein the step of defining a gradual region in each period of the instantaneous optical signal intensity line comprises: the instantaneous optical signal for a certain period of time A region in which the amount of change in the intensity sample value is smaller than the reference value is defined as the gradation region, wherein the reference value ranges from 0.1% to 10% of the maximum value of the instantaneous light signal intensity sample value in the period. The endpoint detection method of a plasma processing process according to claim 2, wherein the step of defining a gradation region in each period of the instantaneous light signal intensity spectrum line comprises: The area where the instantaneous optical signal strength sample value is within a predetermined range and the amount of change of the instantaneous optical signal strength sample value is less than a reference value within a certain period of time is defined as the gradation area, wherein the reference value ranges from The maximum value of the instantaneous optical signal intensity sample value in the period is 0.1% to 10%. The method for detecting an end point of a plasma processing process according to claim 1, wherein the step of extracting one of the instantaneous optical signal strength samples in each of the gradual regions as the optical signal strength characteristic value comprises: determining the gradual The number of the instantaneous optical signal strength samples in the area; when the number of the instantaneous optical signal strength samples is 2N-1, extracting the Nth instantaneous optical signal strength sample value as the optical signal strength characteristic value; When the number of the instantaneous optical signal strength sample values is 2N, the Nth or N+1th instantaneous optical signal strength sample value is extracted as the optical signal strength characteristic value, where N is a positive integer greater than 1. The endpoint detection method of a plasma processing process according to claim 1, wherein the determining the end point of the plasma processing process according to the optical signal intensity characteristic line comprises: determining, according to the optical signal intensity characteristic line An inflection point of the feature value; and determining an end point of the plasma processing process based on the inflection point of the feature value. The endpoint detection method of a plasma processing process according to claim 1, wherein each of said plasma processing steps includes an etching step and a deposition step. An end point detecting device for a plasma processing process, the plasma processing process comprising a plurality of periodic plasma processing steps, the end point detecting device comprising: The signal acquisition module is configured to acquire the instantaneous optical signal intensity of the specific wavelength during the plasma processing process at a certain time interval to obtain a plurality of instantaneous optical signal intensity sampling values and establish a periodic optical signal intensity spectrum line. The instantaneous optical signal intensity corresponds to a concentration of a reactant component or a product component of the plasma processing process; a gradual zone defining module is coupled to the signal acquisition module for use in the instantaneous optical signal strength Defining a gradual zone in each cycle of the line, the gradual zone having at least one of the instant optical signal strength samples; a feature value extraction module, and the gradual zone definition module for each Extracting an instant optical signal strength sample value in the gradual region as an optical signal strength feature value; a feature line establishing module connected to the eigenvalue extraction module for establishing light according to the optical signal intensity characteristic value a signal strength characteristic line; and an end point determining module connected to the characteristic line establishing module for determining a characteristic line according to the optical signal intensity The end point of the plasma treatment process. The endpoint detection apparatus of a plasma processing process according to claim 8, wherein said gentle region has at least two of said instantaneous optical signal strength samples. The end point detecting device of the plasma processing process according to claim 9, wherein the gradual area defining module samples the instantaneous optical signal intensity in a certain period of time according to the change of the instantaneous optical signal intensity sampling value. The area where the amount of change is less than the reference value is defined as the gradual area, wherein the reference value ranges from 0.1% to 10% of the maximum value of the instantaneous optical signal strength sample value in the period. The end point detecting device of the plasma processing process according to claim 9, wherein the gradual area defining module is based on the intensity of the instant optical signal and the intensity of the instantaneous optical signal And changing, the region in which the instantaneous optical signal strength sample value is within a predetermined range and the amount of change in the instantaneous optical signal strength sample value is less than a reference value in a certain period of time is defined as the gradation region, wherein the reference value is The maximum value of the instantaneous optical signal intensity sample value in the period is 0.1% to 10%. The method for detecting an endpoint of a plasma processing process according to claim 8, wherein the feature value extraction module comprises a determination sub-module and an extraction sub-module, and the determination sub-module is configured to determine the gradual region The number of the instantaneous optical signal strength samples; the extraction sub-module is connected to the determination sub-module, and when the number of the instantaneous optical signal samples is 2N-1, extracting the Nth instantaneous optical signal strength The sampled value is used as the characteristic value of the optical signal strength; when the number of samples of the instant optical signal is 2N, the Nth or N+1th instantaneous optical signal intensity sample value is extracted as the optical signal strength characteristic value. Where N is a positive integer greater than one. The endpoint detection method of the plasma processing process of claim 8, wherein the endpoint determination module further comprises a feature value inflection point search sub-module and an end point determination sub-module, and the feature value inflection point search sub-module is The optical signal intensity characteristic line determines a feature value inflection point; the end point determination sub-module is connected to the feature value inflection point search sub-module, and an end point of the plasma processing process is determined according to the feature value inflection point. The endpoint detection method of a plasma processing process according to claim 8, wherein each of said plasma processing steps includes an etching step and a deposition step.