Method and device for detecting electric arc of plasma processing chamber

Abstract

The invention discloses a method and a device for detecting an electric arc of a plasma processing chamber, and the method comprises the steps: transmitting radio frequency power into the plasma processing chamber through a radio frequency power source, and igniting a reaction gas in the plasma processing chamber to form plasma; the variance and the average value of the reflection power signals of the radio frequency power source within the sampling time period length are obtained in real time through the controller; the controller estimates the number of peak values of the reflection power signals in the corresponding sampling time period length according to the variance and the average value of the reflection power signals, and when the number of the peak values of the reflection power signals is smaller than a preset threshold value, it is judged that arc discharge occurs. According to the invention, the purpose of rapidly detecting the micro-arc in the electric arc in the vacuum reaction cavity so as to timely know the defect state of the corresponding wafer is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma processing devices, and in particular to a method and a device for detecting an arc in a plasma processing chamber. Background Art

[0002] Current plasma processing devices such as plasma enhanced chemical vapor deposition (PE-CVD) systems, plasma etching systems and sputtering systems are widely used in semiconductor production equipment throughout the production process of modern electronic devices. Plasma processing devices use the working principle of a vacuum reaction chamber to process semiconductor substrates and plasma flat panels. The working principle of a vacuum reaction chamber is to introduce a reaction gas containing an appropriate etchant or deposition source gas into the vacuum reaction chamber, and then input radio frequency energy to the vacuum reaction chamber to activate the reaction gas to ignite and maintain plasma, so as to etch a material layer on the surface of the substrate or deposit a material layer on the surface of the substrate, and then process the semiconductor substrate and the plasma flat panel. Since the plasma has a higher potential than the side wall of the vacuum reaction chamber, or the accumulation of charges on the surface of the substrate can lead to the breakdown of the dielectric material, thereby causing micro-arcs in the vacuum reaction chamber. The micro-arcs generated by the high plasma potential in the vacuum reaction chamber usually last for several microseconds. When a micro-arc occurs, a large current discharge will inevitably occur in the plasma processing device, and correspondingly, current / power spikes will be generated in various circuits input to the plasma reaction chamber.

[0003] like Figure 1As shown, the prior art usually detects the voltage at the output end of the ESC power supply 30 connected to the electrostatic chuck 20 to determine the arc discharge phenomenon, and a detector 40 is used to detect the output voltage fluctuation of the DC high-voltage power supply (ESC power supply) 30. The PLC circuit 50 is connected to the output end of the detector, and the corresponding information is transmitted to the main controller 60 after processing the detected voltage signal. Since the ESC power supply 30 is provided with a voltage divider circuit, the voltage divider circuit reduces the DC high voltage to a sufficiently low voltage signal, so that it can be detected and transmitted to the main controller 60. The detector 40 is designed to detect the DC signal with a stable voltage output by the output high-voltage DC power supply 30, so the sampling rate is very low, and the discharge with a very short discharge time (several milliseconds) cannot be sampled and detected. Even if a higher level detector 40 is selected to sample the voltage fluctuation signal caused by discharge, since the communication time between the PLC circuit 50 and the main controller 60 in the plasma processing device is now about 200 milliseconds, the arc discharge, especially the micro-arc discharge, is much less than 200ms (such as several milliseconds). For the existing common pulsed plasma processing process (the output RF power changes rapidly in a pulsed manner, such as a 10K pulse frequency), the detected voltage signal also changes at a high speed due to the high-speed change of the RF power itself, which will cause a large number of erroneous discharge signals to be generated. Moreover, due to the large delay, this erroneous signal cannot correspond to the current process step, so it is impossible to distinguish whether it is caused by the sudden change of output power or the discharge. The presence of micro-arcs will cause pollutants from the side wall of the vacuum reaction chamber to gather on the wafer 10 being processed in the vacuum reaction chamber, resulting in defective wafers 10. The defective wafers 10 will affect the progress of subsequent processes, so there is an urgent need for a method that can effectively detect micro-arcs. Summary of the invention

[0004] The object of the present invention is to provide a method and device for detecting an arc in a plasma processing chamber, so as to quickly detect a micro-arc in an arc in a vacuum reaction chamber so as to timely know the defect status of the corresponding wafer.

[0005] In order to achieve the above objectives, the present invention is implemented by the following technical solutions:

[0006] A method for detecting an electric arc in a plasma processing chamber comprises: transmitting radio frequency power into the plasma processing chamber through a radio frequency power source to ignite a reaction gas in the plasma processing chamber to form plasma; obtaining the variance and average value of a reflected power signal of the radio frequency power source in real time within a sampling time period through a controller; the controller estimates the number of peak values ​​of the reflected power signal within the corresponding sampling time period according to the variance and average value of the reflected power signal, and determining that arc discharge occurs when the number of peak values ​​of the reflected power signal is less than a preset threshold.

[0007] Optionally, the RF power source obtains the value of the reflected power signal every 1 ms to 10 ms.

[0008] Optionally, the step of acquiring in real time through the controller the variance and average value of the reflected power signal of the RF power source within the length of the sampling time period includes: the RF power source calculates the variance and average value of the reflected power signal within the length of the sampling time period and returns them to the controller.

[0009] Optionally, the controller estimates the number k of peak values ​​of the reflected power signal within the length of the sampling time period according to the following formula:

[0010]

[0011] Wherein, X represents the average value of the reflected power signal within the sampling time period; σ 2 represents the variance of the reflected power signal within the length of the sampling time period; n represents the number of values ​​of the reflected power signal within the length of the sampling time period.

[0012] Optionally, within the length of the sampling time period, the number of values ​​of the reflected power is n, and the preset threshold is:

[0013] Optionally, within the sampling time period, the ratio of the peak value to the minimum value of the reflected power signal is r, and the value range of r is 10 2 ~10 5 .

[0014] Optionally, there are two RF power sources, which output high-frequency and low-frequency RF power to the reaction chamber respectively, and the two RF power sources independently or jointly send the variance and average value of the reflected power signal to the controller.

[0015] Optionally, it also includes: the range of the sampling time period length t is: 200ms<t≤400ms.

[0016] Optionally, the method further includes: issuing a warning message when the number k of peak values ​​of the reflected power signal is less than the preset threshold within the sampling time period.

[0017] Optionally, the number k corresponding to the issuance of the warning information is accumulated to obtain a cumulative value. When the cumulative value is greater than or equal to a preset detection threshold, the detector alarm information is issued and the wafer preparation process is immediately terminated.

[0018] On the other hand, the present invention also provides an arc detection device in a plasma processing chamber, which is used to detect arc discharge in a plasma processing chamber, and includes: a radio frequency power source and a controller arranged outside the plasma processing chamber. The radio frequency power source is used to deliver radio frequency power to the plasma processing chamber to ignite the reaction gas introduced into the plasma processing chamber to form plasma; the radio frequency power source simultaneously detects a reflected power signal reflected from the plasma processing chamber back to the radio frequency power source. The controller acquires the variance and average value of the reflected power signal of the radio frequency power source in real time within the length of a sampling time period. The controller estimates the number of peak values ​​of the reflected power signal within the corresponding length of the sampling time period based on the variance and average value of the reflected power signal, and determines that arc discharge occurs when the number of peak values ​​of the reflected power signal is less than a preset threshold.

[0019] Optionally, the RF power source obtains the value of the reflected power signal every 1 ms to 10 ms.

[0020] Optionally, the RF power source calculates the variance and average value of the reflected power signal within the sampling time period and returns the calculated values ​​to the controller.

[0021] Optionally, the controller estimates the number k of peak values ​​of the reflected power signal within the corresponding sampling time period using the following formula:

[0022]

[0023] Wherein, X represents the average value of the reflected power signal within the sampling time period; σ 2 represents the variance of the reflected power signal within the length of the sampling time period; n represents the number of values ​​of the reflected power signal within the length of the sampling time period.

[0024] Optionally, within the length of the sampling time period, the number of values ​​of the reflected power is n, and the preset threshold is:

[0025] Optionally, within the sampling time period, the ratio of the peak value to the minimum value of the reflected power signal is r, and the value range of r is 10 2 ~10 5 .

[0026] Optionally, there are two RF power sources, which output high-frequency and low-frequency RF power to the reaction chamber respectively, and the two RF power sources independently or jointly send the variance and average value of the reflected power signal to the controller.

[0027] Optionally, it also includes: the range of the sampling time period length t is: 200ms<t≤400ms.

[0028] Optionally, it also includes: a warning device connected to the controller; within the length of the sampling time period, when the number k of the peak values ​​of the reflected power signal is less than the preset threshold, the warning device issues a warning message.

[0029] Optionally, the controller is also used to accumulate the number k corresponding to the issuance of the warning information to obtain a cumulative value. When the cumulative value is greater than or equal to a preset detection threshold, the warning device issues a detector alarm message and immediately terminates the wafer preparation process.

[0030] The present invention has at least one of the following advantages:

[0031] The present invention estimates the number of peak values ​​of the reflected power signal within the corresponding sampling time period through the variance and average value of the reflected power signal, and determines that arc discharge occurs when the number of peak values ​​of the reflected power signal is less than a preset threshold. Since the radio frequency power source has a high-speed data collector inside, it can send or count the information of the reflected power in real time and at a high sampling rate (~10μs interval) and transmit the statistical reflected power information to the controller, so that the controller determines the number of peak values ​​of the reflected power signal within the sampling time period according to the reflected power information, and determines whether the discharge in the plasma processing chamber is caused by micro-arc discharge or by ignition failure or frequency adjustment operation based on this number. This method has better detection accuracy.

[0032] Furthermore, it is possible to quickly detect a micro-arc in an arc in a plasma chamber, so as to timely learn the defect status of a corresponding wafer.

[0033] The present invention prompts the generation of micro-arcs by issuing a warning message, thereby allowing people to intuitively know that micro-arc discharges have occurred in the plasma chamber, making it easier to roughly know the defect state of the wafer.

[0034] The present invention prompts through the detector alarm information that too many micro-arcs are generated, reaching a level where the equipment can be stopped, thereby improving the wafer yield and saving manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the main structure of an arc detection device for a plasma processing chamber in the prior art;

[0036] Figure 2a A timing diagram of a reflected power signal detected by a radio frequency power source when a micro-arc event occurs, provided for a measurement scheme;

[0037] Figure 2bA timing diagram of a reflected power signal detected by a radio frequency power source when a high reflected power signal not caused by a micro-arc occurs, provided for a measurement solution;

[0038] Figure 3 A schematic diagram of a flow chart of a method for detecting an arc in a plasma processing chamber provided in accordance with an embodiment of the present invention

[0039] Figure 4 A timing diagram of a reflected power signal detected by a radio frequency power source when a high reflected power signal not caused by a micro-arc occurs, provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0040] As described in the background technology, the existing arc detection device for the plasma processing chamber has the following defects: the sampling rate of the detector is very low, and it is impossible to sample and detect the discharge with extremely short discharge time. Even if a higher-level detector is used to sample the voltage fluctuation signal caused by the discharge, for the existing common pulsed plasma processing process, the high-speed change of the RF power itself causes the detected voltage signal to change at a high speed, which will cause a large number of erroneous discharge signals to be generated, and it is impossible to distinguish whether it is caused by the sudden change of output power or the discharge.

[0041] According to the feedback signal that the RF power source can provide, such as the average value and the maximum value, there is a micro-arc detection method, which uses the difference (Pr_Delta) between the average reflected power value (Pr_Avg) or the maximum reflected power value (Pr_Max) of the reflected power signal fed back by the RF power source and the average reflected power value (Pr_Avg) as the standard for detecting the occurrence of micro-arcs. The standard can be Pr_Avg>threshold, or Pr_Delta>threshold.

[0042] For example, Figure 2a As shown, it provides a technical solution for determining micro-discharge using the maximum value P and the average value A. Figure 2a The above figure is a real reflection power signal variation diagram generated over time. However, in actual work, it is not possible to monitor such detailed data from the RF source. If the technology can obtain Figure 2a The data in the figure above can directly determine the arc discharge situation. The data that can be obtained from the RF source can only be Figure 2a The figure below is the waveform of the average value A and the maximum value P of the reflected power signal after data processing. Because data processing takes time, Figure 2a The average and maximum values ​​reflected in the figure below will have a time delay compared to what actually happened in the figure above. When there is no micro-arc, the difference between the average value A and the maximum value P is relatively small. When the reflected power suddenly changes, the difference between the two will become larger, and it can be determined that a micro-discharge event has occurred.

[0043] However, in actual use, this judgment criterion may also be triggered by high reflected power caused by impedance mismatch, that is, there is a high reflected power signal during the sampling period, but this high reflected power signal lasts for a long time and has a large peak width. This reflected power signal is not caused by micro-arc discharge, but may be caused by ignition failure or preset / frequency adjustment errors.

[0044] For example, Figure 2b As shown, Figure 2b The spike in the upper figure lasts longer and does not end instantly, but after data processing, Figure 2b The waveforms in the lower and middle figures are Figure 2a The waveforms in the figure below are basically the same. The maximum value P fed back by the RF power source is also a straight line much higher than the average value A; that is, the maximum value P is greater than the average value A. However, the actual situation is that this peak is a mutation caused by RF adjustment, not a mutation caused by micro-arc discharge. Therefore, using the maximum value P greater than the average value A as the standard for detecting micro-arc discharge will result in inaccurate detection.

[0045] Based on the above research, this embodiment provides a method for detecting an arc in a plasma processing chamber, by estimating the number of peak values ​​of the reflected power signal within the corresponding sampling time period through the variance and average value of the reflected power signal. When the number of peak values ​​of the reflected power signal is less than a preset threshold value, the peak width value is small, and such a reflected power signal can be determined to be caused by micro-arc discharge, thereby determining that arc discharge occurs. It can be seen that this method can not only realize the rapid detection of micro-arcs in the arc in the vacuum reaction chamber, so as to timely know the defect status of the corresponding wafer, but also have better detection accuracy.

[0046] The following is a further detailed description of the arc detection method and detection device for a plasma processing chamber proposed by the present invention in combination with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects that can be produced by the present invention and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention.

[0047] like Figure 3As shown, the present embodiment provides a method for detecting an arc in a plasma processing chamber, comprising: step S1, transmitting radio frequency power into the plasma processing chamber through a radio frequency power source to ignite the reaction gas in the plasma processing chamber to form plasma.

[0048] Step S2: obtaining in real time through the controller the variance and average value of the reflected power signal of the radio frequency power source within the sampling time period.

[0049] Step S3, the controller estimates the number of peak values ​​of the reflected power signal within the corresponding sampling time period according to the variance and average value of the reflected power signal, and determines that arc discharge occurs when the number of peak values ​​of the reflected power signal is less than a preset threshold.

[0050] Therefore, when the number of peak values ​​of the reflected power signal is less than the preset threshold value, the embodiment of the present invention knows that the peak width of the reflected power signal is small, and thus it can be determined that the reflected power signal is caused by micro-arc discharge, thereby determining that arc discharge has occurred in the plasma processing chamber. Compared with the detection method in the prior art that uses the average reflected power value Pr_Avg or the difference value Pr_Delta as the judgment standard, the embodiment of the present invention has better detection accuracy.

[0051] In this embodiment, the step of obtaining the variance and average value of the reflected power signal of the RF power source in real time within the sampling time period by the controller includes: the RF power source calculates the variance and average value of the reflected power signal within the sampling time period and returns them to the controller. It can be seen that this embodiment can quickly detect micro-arcs in the electric arc in the vacuum reaction chamber, so as to timely know the defect status of the corresponding wafer.

[0052] In this embodiment, the RF power source obtains the value of the reflected power signal every 1 ms to 10 ms. Within the sampling time length, the RF power source can obtain n (n is a natural number) values ​​of the reflected power signal, and the values ​​of the n reflected power signals are in the form of a sequence X i , i∈[1,n] represents.

[0053] A series of values ​​X i Variance and average The mathematical definition of is as follows:

[0054]

[0055]

[0056] The quotient of the square of the variance and the mean is:

[0057]

[0058] Assume an extreme case as an approximation of the model, the sequence X i is a distribution with only 2 values, that is, suppose in the sequence X i In the equation, there are k items of the peak value X_max of the reflected power signal and nk items X_min other than the peak value. The middle item r is calculated using the following formula:

[0059]

[0060] According to the variance σ of the reflected power signal 2 and average The mathematical formula for calculating the variance σ of the reflected power signal is 2 and average The ratio of the squares of :

[0061]

[0062] Substituting r into the above formula, we get:

[0063]

[0064] The above formula can be approximated to obtain:

[0065]

[0066]

[0067] In this embodiment, the controller estimates the number k of peak values ​​of the reflected power signal within the length of the sampling time period according to formula (8).

[0068] In this embodiment, within the length of the sampling time period, the number of values ​​of the reflected power is n, and the preset threshold is:

[0069] In this embodiment, within the sampling time period, the ratio of the peak value to the minimum value of the reflected power signal is r, and the value range of r is 10 2 ~10 5 , that is, after the minimum value is determined, a peak can be considered to have occurred within the range of r.

[0070] like Figure 4 As shown, Figure 4 The figure above shows a sharp peak with a wide peak width, which is not caused by the change of reflected power caused by micro-arc discharge. Figure 4The figure below shows the variance F and average value A of the reflected power signal fed back by the RF power source. Then, the k value is calculated according to formula (8). The k value is greater than the preset threshold, which means that there are multiple time coordinates with peak values ​​far exceeding the average value between 5.2 seconds and 5.4 seconds in the sampling time period. The k value is greater than the preset threshold, that is, in the actual reflected power change, the duration of the peak value is very long. It can be judged from this that Figure 4 The spikes shown in the figure above are not caused by micro-arcing, but by other factors.

[0071] On the contrary, if the k value is very small, the k value is less than the preset threshold, which means that the duration of the spike is short. Figure 4 The spikes shown in the figure above are caused by micro-arcs rather than other factors, which can avoid misjudgment caused by relying solely on the maximum value and average value.

[0072] Therefore, the detection standard adopted in this embodiment has better accuracy than the existing micro-arc detection scheme.

[0073] In this embodiment, the number of the RF power sources is two, and the high-frequency and low-frequency RF power are output to the reaction chamber respectively. The two RF power sources independently or in combination send the variance and average value of the reflected power signal to the controller. In this embodiment, the number of the RF power sources is not limited thereto, and may be more than two.

[0074] In the pulse processing process, the RF power source outputs pulse power with a pulse frequency of 100 Hz-100 KHz, and the controller receives the RF power signal to obtain the micro-arc signal in the impedance stabilization matching stage in each pulse step.

[0075] This embodiment also includes: within the length of the sampling time period, when the number k of the peak values ​​of the reflected power signal is less than the preset threshold, a warning message is issued. When the number k of the peak values ​​of the reflected power signal is greater than the preset threshold, the issued warning message is ignored. Because within the length of the sampling time period, the duration of micro-arc discharge will be very short, and the RF power fluctuation will last for a long time, so if there is a peak value corresponding to each moment, if the number is too large, then the actual situation is most likely a continuous peak rather than an isolated peak caused by micro-arc discharge. This embodiment prompts the generation of micro-arcs through the issued warning message, so that people can intuitively know that micro-arc discharge has occurred in the plasma chamber, which is convenient for roughly knowing the defect state of the wafer.

[0076] In this embodiment, the number k corresponding to the issuance of the warning information is accumulated to obtain a cumulative value. When the cumulative value is greater than or equal to a preset detection threshold, the detector alarm information is issued and the wafer preparation process is immediately terminated.

[0077] This embodiment uses the detector alarm information to prompt that too many micro-arcs are generated, reaching a level where the equipment can be stopped, thereby improving the wafer yield and saving manufacturing costs.

[0078] In this embodiment, the preset threshold is used to determine whether it is a discharge when a single high reflected power event occurs, that is, a discharge is prompted when k is less than the preset threshold. The preset detection threshold is used to deal with the situation where a small amount of discharge does not affect the overall process in some cases, but multiple discharges require shutdown maintenance, so the preset detection threshold is set as the cumulative value of the number of discharges. That is, in the embodiment, the preset threshold is less than the preset detection threshold.

[0079] The detector alarm information and warning information may be one or two and may be issued simultaneously.

[0080] On the other hand, based on the same inventive concept, this embodiment also provides an arc detection device in a plasma processing chamber, which is used to detect arc discharge in a plasma processing chamber, including: an RF power source and a controller arranged outside the plasma processing chamber. The RF power source is used to deliver RF power to the plasma processing chamber to ignite the reaction gas introduced into the plasma processing chamber to form plasma; the RF power source simultaneously detects the reflected power signal reflected from the plasma processing chamber back to the RF power source. The controller obtains the variance and average value of the reflected power signal of the RF power source in real time within the length of the sampling time period. The controller estimates the number of peak values ​​of the reflected power signal within the corresponding length of the sampling time period based on the variance and average value of the reflected power signal, and determines that arc discharge occurs when the number of peak values ​​of the reflected power signal is less than a preset threshold.

[0081] In this embodiment, the RF power source obtains the value of the reflected power signal every 1 ms to 10 ms.

[0082] In this embodiment, the RF power source calculates the variance and average value of the reflected power signal within the sampling time period and returns the calculated values ​​to the controller.

[0083] In this embodiment, the controller estimates the number k of peak values ​​of the reflected power signal within the corresponding sampling time period using the following formula:

[0084]

[0085] Wherein, X represents the average value of the reflected power signal within the sampling time period; σ 2 represents the variance of the reflected power signal within the length of the sampling time period; n represents the number of values ​​of the reflected power signal within the length of the sampling time period.

[0086] In this embodiment, within the length of the sampling time period, the number of values ​​of the reflected power is n, and the preset threshold is:

[0087] In this embodiment, within the sampling time period, the ratio of the peak value to the minimum value of the reflected power signal is r, and the value range of r is 10 2 ~10 5 .

[0088] In this embodiment, the number of the RF power sources is two, which output high-frequency and low-frequency RF power to the reaction chamber respectively, and the two RF power sources independently or jointly send the variance and average value of the reflected power signal to the controller.

[0089] In this embodiment, the sampling time period length t is also in the range of 200ms<t≤400ms.

[0090] In this embodiment, before performing arc detection, the controller may further determine whether to enter the stable RF power output interval by excluding the process of clamping the substrate (chuck) or releasing the substrate (dechuck) when the output power is greater than 500 W, so as to prevent the capture of an erroneous signal caused by a change in RF power that does not actually represent an arc. That is, the output power of the RF power source in the stable RF power output interval is greater than 500 W.

[0091] In this embodiment, the number of the RF power sources is two, and the high-frequency and low-frequency RF power are output to the reaction chamber respectively. The two RF power sources independently or in combination send the variance and average value of the reflected power signal to the controller. In this embodiment, the number of the RF power sources is not limited thereto, and may be more than two.

[0092] In the pulse processing process, the RF power source outputs pulse power with a pulse frequency of 100 Hz-100 KHz, and the controller receives the RF power signal to obtain the micro-arc signal in the impedance stabilization matching stage in each pulse step.

[0093] In this embodiment, it also includes: a warning device connected to the controller, the warning device selects to send a warning signal according to the frequency of the discharge phenomenon detected by the controller; or, the warning device selects to send a warning signal according to the number k of peak values ​​of the reflected power signal within the length of the sampling time period calculated by the controller.

[0094] The above device also includes: a warning device connected to the controller, which selectively sends out a warning signal according to the frequency of the discharge phenomenon detected by the controller.

[0095] During the sampling period, when the number k of the peak values ​​of the reflected power signal is less than the preset threshold, the warning device issues a warning message.

[0096] In this embodiment or some other embodiments, the controller is also used to accumulate the number k corresponding to the issuance of the warning information to obtain a cumulative value. When the cumulative value is greater than or equal to a preset detection threshold, the warning device issues a detector alarm message and immediately terminates the wafer preparation process.

[0097] In summary, the present embodiment provides a method for detecting an arc in a plasma processing chamber, wherein the controller acquires in real time the variance and average value of the reflected power signal of the RF power source within the length of a sampling time period. The controller estimates the number of peak values ​​of the reflected power signal within the corresponding length of the sampling time period based on the variance and average value of the reflected power signal, and determines that arc discharge occurs when the number of peak values ​​of the reflected power signal is less than a preset threshold.

[0098] It can be seen that, in this embodiment, when the number of peak values ​​of the reflected power signal is less than the preset threshold value, it is known that the peak width value of the reflected power signal is small, and it can be determined that this reflected power signal is caused by micro-arc discharge, thereby determining that arc discharge has occurred in the plasma processing chamber. Compared with the detection method in the prior art that uses the average reflected power value Pr_Avg and the reflected power value difference Pr_Delta as the judgment standard, this embodiment has better detection accuracy. Furthermore, it can achieve the purpose of quickly detecting micro-arcs in the electric arc in the vacuum reaction chamber, so as to timely know the defect state of the corresponding wafer.

[0099] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0100] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A method for detecting an arc in a plasma processing chamber, characterized in that: include: The radio frequency power is delivered into the plasma processing chamber through the radio frequency power source to ignite the reaction gas in the plasma processing chamber to form plasma; The controller is used to obtain in real time the variance and average value of the reflected power signal of the radio frequency power source within the sampling time period; The controller estimates the number of peak values ​​of the reflected power signal within the corresponding sampling time period according to the variance and average value of the reflected power signal, and determines that arc discharge occurs when the number of peak values ​​of the reflected power signal is less than a preset threshold.

2. The method for detecting an arc in a plasma processing chamber according to claim 1, wherein: The radio frequency power source obtains the value of the reflected power signal every 1 ms to 10 ms.

3. The method for detecting an arc in a plasma processing chamber according to claim 2, wherein: The step of obtaining the variance and average value of the reflected power signal of the RF power source in real time within the length of the sampling time period through the controller includes: the RF power source calculates the variance and average value of the reflected power signal within the length of the sampling time period and returns them to the controller.

4. The method for detecting an arc in a plasma processing chamber according to claim 1, wherein: The controller estimates the number k of peak values ​​of the reflected power signal within the sampling time period according to the following formula: In the formula, represents the average value of the reflected power signal within the sampling period; σ 2 represents the variance of the reflected power signal within the length of the sampling time period; n represents the number of values ​​of the reflected power signal within the length of the sampling time period.

5. The method for detecting an arc in a plasma processing chamber according to claim 1, wherein: Within the length of the sampling time period, the number of values ​​of the reflected power is n, and the preset threshold is:

6. The method for detecting an arc in a plasma processing chamber according to claim 1, wherein: In the sampling time period, the ratio of the peak value to the minimum value of the reflected power signal is r, and the value range of r is 10 2 ~10 5 .

7. The method for detecting an arc in a plasma processing chamber according to claim 1, wherein: The number of the RF power sources is two, which output high-frequency and low-frequency RF power to the reaction chamber respectively, and the two RF power sources send the variance and average value of the reflected power signal to the controller independently or in combination.

8. The method for detecting an arc in a plasma processing chamber according to claim 1, wherein: Also includes: The range of the sampling time period length t is: 200ms<t≤400ms.

9. The method for detecting an arc in a plasma processing chamber according to claim 4, wherein: Also includes: During the sampling period, when the number k of the peak values ​​of the reflected power signal is less than the preset threshold, a warning message is issued.

10. The method for detecting an arc in a plasma processing chamber according to claim 9, wherein: The number k corresponding to the issuance of the warning information is accumulated to obtain a cumulative value. When the cumulative value is greater than or equal to a preset detection threshold, the detector alarm information is issued and the wafer preparation process is immediately terminated.

11. An arc detection device in a plasma processing chamber, used for detecting arc discharge in a plasma processing chamber, characterized in that: include: A radio frequency power source and a controller disposed outside the plasma processing chamber; The RF power source is used to deliver RF power into the plasma processing chamber to ignite the reaction gas introduced into the plasma processing chamber to form plasma; the RF power source simultaneously detects a reflected power signal reflected from the plasma processing chamber back to the RF power source; The controller acquires in real time the variance and average value of the reflected power signal of the radio frequency power source within the length of the sampling time period; The controller estimates the number of peak values ​​of the reflected power signal within the corresponding sampling time period according to the variance and average value of the reflected power signal, and determines that arc discharge occurs when the number of peak values ​​of the reflected power signal is less than a preset threshold.

12. The arc detection device in a plasma processing chamber according to claim 11, characterized in that: The radio frequency power source obtains the value of the reflected power signal every 1 ms to 10 ms.

13. The arc detection device in a plasma processing chamber according to claim 12, characterized in that: The RF power source calculates the variance and average value of the reflected power signal within the sampling time period and returns the calculated values ​​to the controller.

14. The arc detection device in a plasma processing chamber according to claim 13, characterized in that: The controller estimates the number k of peak values ​​of the reflected power signal within the corresponding sampling time period using the following formula: In the formula, represents the average value of the reflected power signal within the sampling period; σ 2 represents the variance of the reflected power signal within the length of the sampling time period; n represents the number of values ​​of the reflected power signal within the length of the sampling time period.

15. The arc detection device in a plasma processing chamber according to claim 11, characterized in that: Within the length of the sampling time period, the number of values ​​of the reflected power is n, and the preset threshold is:

16. The arc detection device in a plasma processing chamber according to claim 11, characterized in that: In the sampling time period, the ratio of the peak value to the minimum value of the reflected power signal is r, and the value range of r is 10 2 ~10 5 .

17. The arc detection device in a plasma processing chamber according to claim 11, characterized in that: The number of the RF power sources is two, which output high-frequency and low-frequency RF power to the reaction chamber respectively, and the two RF power sources send the variance and average value of the reflected power signal to the controller independently or in combination.

18. The arc detection device in a plasma processing chamber according to claim 11, characterized in that: Also includes: The range of the sampling time period length t is: 200ms<t≤400ms.

19. The arc detection device in a plasma processing chamber according to claim 11, characterized in that: Also included: a warning device connected to the controller; During the sampling period, when the number k of the peak values ​​of the reflected power signal is less than the preset threshold, the warning device issues a warning message.

20. The arc detection device in a plasma processing chamber according to claim 19, characterized in that: The controller is also used to accumulate the number k corresponding to the issuance of the warning information to obtain a cumulative value. When the cumulative value is greater than or equal to a preset detection threshold, the warning device issues a detector alarm message and immediately terminates the wafer preparation process.

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