CN111293021B

CN111293021B - Impedance matching method and device for pulse radio frequency plasma

Info

Publication number: CN111293021B
Application number: CN201811495750.5A
Authority: CN
Inventors: 叶如彬; 涂乐义
Original assignee: Advanced Micro Fabrication Equipment Inc Shanghai
Current assignee: Advanced Micro Fabrication Equipment Inc Shanghai
Priority date: 2018-12-07
Filing date: 2018-12-07
Publication date: 2024-01-12
Anticipated expiration: 2038-12-07
Also published as: CN111293021A; TWI711345B; TW202024973A

Abstract

The application discloses an impedance matching method and device for pulse radio frequency plasma. In the method, in the process of searching the matching frequency in the ith pulse period and the first radio frequency power stage of a plurality of pulse periods positioned behind the ith pulse period, the specific allocation frequency read in the process of searching the matching frequency of the previous pulse is given to the next pulse and is used as the initial frequency of the next pulse, so that the width of the first radio frequency power stage of one pulse period is increased, and the matching frequency of the pulse radio frequency plasma with higher pulse frequency can be searched through continuous frequency modulation of the first radio frequency power stage of the plurality of pulses, and the impedance matching of the plasma with higher pulse frequency is realized. In addition, the application also discloses a plasma processing device.

Description

Impedance matching method and device for pulse radio frequency plasma

Technical Field

The present disclosure relates to the field of pulsed rf plasmas, and in particular, to a method and apparatus for impedance matching of pulsed rf plasmas.

Background

The radio frequency power of the pulse radio frequency plasma has high output power and low output power; in response, the impedance of the plasma also has a high impedance and a low impedance. In the fm-match plasma technology, in order to reduce the frequency mismatch problem caused by the large-range jump of the rf frequency, two different matching rf frequencies are required to match the impedance of the plasma in both the high and low states. Thus, the automatic frequency modulation impedance matching technique is required to search for the corresponding matching frequency in the high power and low power phases of the pulsed rf power.

Existing auto-frequency-modulated impedance matching techniques require several or tens of frequency modulations (in about 5-10 mus) to find the matching frequency. Such a frequency modulation rate may be sufficient to enable impedance matching at the high-low power stage of a pulsed rf plasma at medium-low pulse frequencies (e.g., 100-1000 Hz). However, for the pulsed rf plasma with higher pulse frequency, such as 5000Hz, because the pulse width is narrower, the frequency modulation frequency in each pulse period is less, so it is difficult to find the matching frequency in the single pulse section of the pulsed rf plasma with higher pulse frequency by using the existing automatic frequency modulation impedance matching technology, and thus the impedance matching for the plasma with higher pulse frequency cannot be realized.

Disclosure of Invention

In view of this, the present invention provides an impedance matching method and apparatus for pulsed rf plasma to find the matching frequency of the pulsed rf plasma with higher pulse frequency, so as to achieve impedance matching for the plasma with higher pulse frequency.

In order to solve the technical problems, the application adopts the following technical scheme:

a first aspect of the present application provides an impedance matching method for pulsed radio frequency plasma, comprising:

Providing pulsed radio frequency power to a plasma reaction chamber, the pulsed radio frequency power comprising n pulse periods, each pulse period comprising a first radio frequency power stage; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer;

acquiring a first initial frequency in a first radio frequency power stage of an ith pulse period; i < n, and i is a positive integer;

searching matching frequency in the ith pulse period and the first radio frequency power stages of a plurality of pulse periods positioned behind the ith pulse period continuously according to the first initial frequency until the impedance parameter corresponding to the searched frequency modulation frequency reaches an extremum, and reading the specific frequency modulation frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period; wherein, in the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period, the specific frequency modulation frequency of the first radio frequency power stage of the previous pulse period of the two adjacent pulse periods is used as the initial frequency of the first radio frequency power stage of the next pulse period;

and determining the corresponding radio frequency when the impedance parameter reaches the extreme value as the matching frequency of the first radio frequency power stage of the pulse radio frequency power and the plasma impedance.

As a possible implementation, the first initial frequency is a manually assigned frequency or a frequency obtained by previous auto-tuning.

As a possible implementation manner, the specific fm frequency is a matching frequency that is found in the first rf power phase of the pulse period in which the specific fm frequency matches the plasma impedance, or is a fm frequency that is randomly read during the search for the matching frequency in the first rf power phase of the pulse period in which the specific fm frequency is found.

As a possible implementation, the plurality of pulse periods located after the ith pulse period are a plurality of consecutive pulse periods adjacent to the ith pulse period.

As one possible implementation, the plurality of pulse periods located after the ith pulse period are a plurality of pulse periods spaced apart from the ith pulse period by at least one pulse period and spaced apart therebetween by at least one pulse period.

The second aspect of the present application provides an impedance matching method for pulsed rf plasma, where pulsed rf power including n pulse periods is divided into a plurality of rf frequency modulation paths in advance, where each rf frequency modulation path includes at least two non-adjacent pulse periods; each pulse period includes a first radio frequency power phase; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer;

The method comprises the following steps: respectively carrying out impedance matching on the pulse radio frequency plasmas in each radio frequency modulation path;

the impedance matching method for the pulse radio frequency plasma of the radio frequency modulation path specifically comprises the following steps:

acquiring a first initial frequency in a first radio frequency power stage of a j-th pulse period in a radio frequency modulation path; setting the number of pulse periods included in the impedance radio frequency modulation path as m, wherein m is less than n, j is less than m, and j and m are positive integers;

searching matching frequency in the j-th pulse period and the first radio frequency power stage of a plurality of pulse periods positioned behind the j-th pulse period in the radio frequency modulation path continuously according to the first initial frequency until the impedance parameter corresponding to the searched frequency modulation frequency reaches an extremum, and reading the specific frequency modulation frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period; the specific frequency modulation frequency of the first radio frequency power stage of the previous pulse period of two adjacent pulse periods is used as the initial frequency of the first radio frequency power stage of the next pulse period in the j-th pulse period and a plurality of pulse periods positioned behind the j-th pulse period in the radio frequency modulation path;

And determining the corresponding radio frequency when the impedance parameter reaches the extremum as the matching frequency of the plasma impedance at the first radio frequency power stage of the pulse radio frequency power in the radio frequency modulation path.

As a possible implementation, the at least two non-adjacent pulse periods included in each of the rf frequency modulation paths are a plurality of equally spaced non-adjacent pulse periods.

A third aspect of the present application provides an impedance matching method for pulsed radio frequency plasma, comprising:

dividing the pulse radio frequency power comprising n pulse periods into K adjacent radio frequency modulation intervals, wherein each radio frequency modulation interval comprises at least one pulse period; the pulse period includes a first radio frequency power phase; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer, K is not less than 2, and K is a positive integer;

Acquiring a first initial frequency of a kth radio frequency modulation interval, wherein K is less than K and is a positive integer;

searching matching frequencies in the kth radio frequency modulation interval and each pulse period in a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval continuously according to the first initial frequency until impedance parameters corresponding to the searched frequency modulation frequencies reach an extremum, and reading specific frequency modulation frequencies in the process of searching the matching frequencies in the first radio frequency power stage of each pulse period of each radio frequency modulation interval in the process of searching the matching frequencies in the first radio frequency power stage of each radio frequency modulation interval; wherein, in the kth radio frequency modulation interval and a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval, the specific frequency modulation frequency of the first radio frequency power stage of the previous radio frequency modulation interval of two adjacent radio frequency modulation intervals is used as the initial frequency of the first radio frequency power stage of the next radio frequency modulation interval;

As a possible implementation manner, the specific tuning frequency is a matching frequency matched with the plasma impedance and found in the first rf power stage of each pulse period of the rf tuning interval, or is a tuning frequency randomly read during the searching of the matching frequency in the first rf power stage of each pulse period of the rf tuning interval.

As a possible implementation manner, the number of pulse periods of each radio frequency modulation interval is set to any integer value.

A fourth aspect of the present application provides an impedance matching device for pulsed radio frequency plasma, comprising:

a providing unit for providing pulsed radio frequency power to the plasma reaction chamber, the pulsed radio frequency power comprising n pulse periods, each pulse period comprising a first radio frequency power stage; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer;

an acquisition unit, configured to acquire a first initial frequency in a first rf power phase of an ith pulse period; i < n, and i is a positive integer;

the searching unit is used for continuously searching the matching frequency in the first radio frequency power stage of the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period according to the first initial frequency until the impedance parameter corresponding to the searched frequency modulation frequency reaches the extremum, and reading the specific frequency modulation frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period; wherein, in the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period, the specific frequency modulation frequency of the first radio frequency power stage of the previous pulse period of the two adjacent pulse periods is used as the initial frequency of the first radio frequency power stage of the next pulse period;

And the determining unit is used for determining the corresponding radio frequency when the impedance parameter reaches the extreme value as the matching frequency of the first radio frequency power stage of the pulse radio frequency power and the plasma impedance.

A fifth aspect of the present application provides an impedance matching device for pulsed radio frequency plasma, comprising:

the dividing unit is used for dividing the pulse radio frequency power comprising n pulse periods into a plurality of radio frequency modulation paths in advance, wherein each radio frequency modulation path comprises at least two non-adjacent pulse periods; each pulse period includes a first radio frequency power phase; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer;

the impedance matching unit is used for respectively carrying out impedance matching on the pulse radio frequency plasmas in each radio frequency modulation path;

the impedance matching unit specifically includes:

an acquisition unit, configured to acquire a first initial frequency in a first rf power stage of a j-th pulse period in an rf frequency modulation path; setting the number of pulse periods included in the impedance radio frequency modulation path as m, wherein m is less than n, j is less than m, and j and m are positive integers;

the searching unit is used for continuously searching the matching frequency in the j-th pulse period and the first radio frequency power stage of the pulse periods in the radio frequency modulation path according to the first initial frequency until the impedance parameter corresponding to the searched frequency modulation frequency reaches the extremum, and reading the specific frequency modulation frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period; the specific frequency modulation frequency of the first radio frequency power stage of the previous pulse period of two adjacent pulse periods is used as the initial frequency of the first radio frequency power stage of the next pulse period in the j-th pulse period and a plurality of pulse periods positioned behind the j-th pulse period in the radio frequency modulation path;

And the determining unit is used for determining the corresponding radio frequency when the impedance parameter reaches the extreme value as the matching frequency of the first radio frequency power stage of the pulse radio frequency power in the radio frequency modulation path and the plasma impedance.

A sixth aspect of the present application provides an impedance matching device for pulsed radio frequency plasma, comprising:

the dividing unit is used for dividing the pulse radio frequency power comprising n pulse periods into K adjacent radio frequency modulation intervals, wherein each radio frequency modulation interval comprises at least one pulse period; the pulse period includes a first radio frequency power phase; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer, K is not less than 2, and K is a positive integer;

the acquisition unit is used for acquiring a first initial frequency of a kth radio frequency modulation interval, wherein K is less than K and is a positive integer;

the searching unit is used for continuously searching the matching frequency in the kth radio frequency modulation interval and each pulse period in a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval according to the first initial frequency until the impedance parameter corresponding to the searched frequency modulation frequency reaches the extremum, and reading the specific frequency modulation frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period of each radio frequency modulation interval; wherein, in the kth radio frequency modulation interval and a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval, the specific frequency modulation frequency of the first radio frequency power stage of the previous radio frequency modulation interval of two adjacent radio frequency modulation intervals is used as the initial frequency of the first radio frequency power stage of the next radio frequency modulation interval;

A seventh aspect of the present application provides a plasma processing apparatus, comprising:

a plasma processing chamber and a radio frequency power generator;

the plasma processing cavity is used for accommodating and processing a substrate;

the radio frequency power generator is used for outputting pulse radio frequency power to the plasma reaction cavity, the pulse radio frequency power comprises n pulse periods, and each pulse period comprises a first radio frequency power stage; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer;

the radio frequency power generator comprises an automatic frequency modulation device, and the automatic frequency modulation device is used for executing the impedance matching method of the pulsed radio frequency plasma according to any possible implementation manner of the first aspect.

As one possible implementation manner, the plasma processing apparatus further includes:

the random command generator is used for setting the duration of the radio frequency modulation interval and sending the set duration signal of the radio frequency modulation interval to the radio frequency power generator so that the radio frequency power generator divides the radio frequency modulation interval according to the duration signal of the radio frequency modulation interval.

Compared with the prior art, the application has the following beneficial effects:

based on the above technical solution, in the impedance matching method of the pulsed rf plasma provided in the present application, a first initial frequency in a first rf power stage of an ith pulse period is obtained first, then a matching frequency is continuously searched in the first rf power stage of the ith pulse period and a plurality of pulse periods located behind the ith pulse period according to the first initial frequency until an impedance parameter corresponding to the searched rf frequency reaches an extremum, and finally the rf frequency corresponding to the extremum is determined as a matching frequency of the first rf power stage of the pulsed rf power matched with the plasma impedance.

In the process of searching the matching frequency in the ith pulse period and the first radio frequency power stage of the plurality of pulse periods positioned behind the ith pulse period, the specific allocation frequency read in the process of searching the matching frequency of the previous pulse is given to the next pulse and is used as the initial frequency of the next pulse, so that the width of the first radio frequency power stage of one pulse period is increased, and the matching frequency of the pulse radio frequency plasma with higher pulse frequency can be searched through continuous frequency modulation of the first radio frequency power stage of the plurality of pulses, and further, the impedance matching of the plasma with higher pulse frequency is realized.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of reflected power versus RF source frequency;

fig. 2 is a flowchart of an impedance matching method of a pulsed rf plasma according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of pulsed RF power provided in an embodiment of the present application;

FIG. 4 is a flow chart of an implementation of a method for impedance matching of pulsed RF plasma provided in an embodiment of the present application;

FIG. 5 is a schematic diagram of an implementation of an impedance matching method for pulsed RF plasma provided in an embodiment of the present application;

FIG. 6 is a flowchart of another implementation of the impedance matching method of pulsed RF plasma provided in the embodiments of the present application;

fig. 7 is a schematic diagram of another implementation of an impedance matching method of a pulsed rf plasma provided in an embodiment of the present application;

FIG. 8 is a flowchart of another implementation of the impedance matching method of pulsed RF plasma provided in the embodiments of the present application;

fig. 9 is a schematic diagram of still another implementation of an impedance matching method of a pulsed rf plasma provided in an embodiment of the present application;

fig. 10 is a flowchart of a method for acquiring a first matching frequency according to an embodiment of the present application;

fig. 11 is a flowchart of a method for obtaining a second matching frequency according to an embodiment of the present application;

FIG. 12a is a schematic diagram of an embodiment of dividing pulsed RF power into RF modulation intervals according to the present application;

FIG. 12b is a schematic diagram of another embodiment of the division of pulsed RF power into RF modulation intervals according to the present application;

FIG. 13 is a flowchart of another implementation of the impedance matching method of pulsed RF plasma provided in the examples of this application;

FIG. 14 is a flow chart of an implementation of a method for impedance matching of pulsed RF plasma provided in embodiments of the present application;

FIG. 15 is a schematic diagram of an impedance matching method for pulsed RF plasma according to an embodiment of the present application;

FIG. 16 is a schematic diagram of an impedance matching device for pulsed RF plasma according to an embodiment of the present application;

Fig. 17 is a schematic structural diagram of another implementation of an impedance matching device for pulsed rf plasma provided in an embodiment of the present application;

fig. 18 is a schematic structural diagram of another implementation of an impedance matching device for pulsed rf plasma provided in an embodiment of the present application;

fig. 19 is a schematic structural view of a plasma processing apparatus according to an embodiment of the present application.

Detailed Description

Before describing the embodiments of the present application, first, information about the load impedance of a radio frequency power transmission system is described.

The load impedance of the rf power delivery system is determined by the impedance of the transmission line, the impedance matching network, and the plasma chamber. Experiments prove that any parameter related to the load impedance of the plasma reaction chamber is in a nonlinear function relation with the frequency of the RF source, and the nonlinear function is a nonlinear function with an extremum. And when the load impedance matches the impedance of the RF radio frequency source, any one of the parameters related to the load impedance reaches an extremum at this time.

The impedance parameter related to the load impedance of the plasma reaction chamber is many, and may be, for example, reflected power, reflection coefficient, or impedance. By way of example, fig. 1 shows a schematic diagram of reflected power versus RF source frequency. As can be seen from fig. 1, the reflected power versus RF source frequency is a nonlinear function with a minimum value that is reached when the load impedance matches the RF source impedance. And it can be considered that the matching frequency and its corresponding reflected power are inflection points of a relational curve.

The impedance matching method of the pulse radio frequency plasma is realized based on the principle. Specific embodiments of the impedance matching method for pulsed radio frequency plasma provided by the invention are described in detail below with reference to the accompanying drawings.

The radio frequency power of the pulse radio frequency plasma comprises a high-power radio frequency stage and a low-power radio frequency stage, and when the radio frequency power of the low-power radio frequency stage is zero, only the plasma impedance of the high-power radio frequency stage is required to be matched; when the radio frequency power of the low power radio frequency stage is not zero, not only the plasma impedance of the high power radio frequency stage but also the plasma impedance of the low power radio frequency stage need to be matched. Furthermore, as described in the background section, in order to reduce the frequency mismatch problem caused by the large-range jump of the rf frequency, separate frequency modulation is required for the high-power rf stage and the low-power rf stage.

However, the frequency modulation time required by the existing automatic frequency modulation impedance matching technology is longer than the pulse period of the rf power with high pulse frequency, which cannot find the matching frequency in the single pulse section, and thus cannot realize the impedance matching of the plasma with higher pulse frequency.

Table 1 lists the frequency adjustments within a single low power pulse at different pulse frequencies. In table 1, the frequency modulation time per frequency modulation is exemplified as 10 μs.

TABLE 1

As can be seen from table 1, for some high pulse frequency pulsed plasmas, the frequency modulation of a single pulse is even less than 10 times, and it is difficult to find matching frequencies within a single pulse segment by auto-tuning.

The above problem arises because the rate at which the frequency is generated by the power generator cannot keep pace with the rate at which the frequency is tuned, and thus, the problem of power generator frequency mismatch arises. In order to solve the above technical problem, the function of frequency reading and assignment of the power generator becomes particularly important.

Based on the above, the application provides an impedance matching method of pulse radio frequency plasma. In the method, first initial frequency in a first radio frequency power stage of an ith pulse period is firstly obtained, then matching frequency is continuously searched in the first radio frequency power stage of the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period according to the first initial frequency until impedance parameters corresponding to the searched radio frequency reach an extremum, and finally the radio frequency corresponding to the extremum of the impedance parameters is determined as the matching frequency matched with plasma impedance in the first radio frequency power stage of the pulse radio frequency power.

In the process of searching the matching frequency in the ith pulse period and the first radio frequency power stage of a plurality of pulse periods positioned behind the ith pulse period, the specific allocation frequency read by the previous pulse in the process of searching the matching frequency is assigned to the next pulse and is used as the initial frequency of the next pulse, so that the width of the first radio frequency power stage of one pulse period is increased, and the matching frequency of the pulse radio frequency plasma with higher pulse frequency can be searched through continuous frequency modulation of the first radio frequency power stage of the plurality of pulses, and further, the impedance matching of the plasma with higher pulse frequency is realized.

In order to make the technical problems, technical schemes and technical effects of the application clearer and more complete, the specific implementation mode of the impedance matching method of the pulse radio frequency plasma provided by the application is described in detail below with reference to the accompanying drawings.

Referring to fig. 2, a flowchart of an impedance matching method of a pulsed rf plasma according to an embodiment of the present application is shown.

The impedance matching method of the pulse radio frequency plasma provided by the embodiment of the application comprises the following steps:

s201: pulsed radio frequency power is provided to the plasma reaction chamber.

It should be noted that, the pulsed rf power provided into the plasma reaction chamber includes n pulse periods, where each pulse period includes a first rf power phase; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer.

By way of example, fig. 3 illustrates a schematic diagram of pulsed radio frequency power. As shown in fig. 3, the pulsed rf power comprises n pulse periods, wherein each period comprises a high rf power phase 31 and a low rf power phase 32.

Because the frequencies of the high rf power stage and the low rf power stage need to be tuned separately, in the embodiment of the present application, the first rf power stage may be the high rf power stage 31 or the low rf power stage 32.

S202: acquiring a first initial frequency in a first radio frequency power stage of an ith pulse period; i < n, and i is a positive integer.

The i-th pulse period may be any one of the 1 st to n-1 st pulse periods in the pulsed radio frequency power.

As an example, the present embodiment may be described taking the 1 st pulse period as the i-th pulse period as an example.

The first initial frequency may be obtained in a plurality of ways, and as an example, the first initial frequency may be a manually assigned frequency. As another example, the first initial frequency may be a previously auto-tuned resulting frequency.

S203: searching matching frequency in the ith pulse period and the first radio frequency power stage of a plurality of pulse periods positioned behind the ith pulse period continuously according to the first initial frequency until the impedance parameter corresponding to the searched radio frequency reaches an extremum, and reading a specific frequency modulation frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period; in the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period, the specific frequency modulation frequency of the first radio frequency power stage of the previous pulse period of two adjacent pulse periods is used as the initial frequency of the first radio frequency power stage of the next pulse period.

As an example, S203 may specifically be:

s203a: searching for a matching frequency in a first radio frequency power stage of an ith pulse period according to the first initial frequency, reading and storing the obtained specific frequency modulation frequency, and recording the specific frequency modulation frequency as a first frequency modulation frequency.

It should be noted that in the process of searching for the matching frequency, the radio frequency may be adjusted multiple times according to the frequency modulation time and the pulse width of the first radio frequency power stage, so as to obtain multiple frequency modulation frequencies.

S203b: judging whether impedance parameters corresponding to a plurality of frequency modulation frequencies in the searching process reach an extreme value or not. If yes, executing S204; if not, S203c is performed.

S203c: assigning the first modulation frequency to a first radio frequency power stage of the (i+k) th pulse period, and taking the first modulation frequency as a second initial frequency of the first radio frequency power stage of the (i+k) th pulse period; i+k is less than or equal to n, and k is a positive integer.

S203d: searching for a matching frequency in a first radio frequency power stage of the (i+k) th pulse period according to the second initial frequency, reading and storing the obtained specific frequency modulation frequency, and recording the specific frequency modulation frequency as a second frequency modulation frequency.

The process of searching for the matching frequency is the same as that of S203a, and will not be described in detail here for brevity.

S203e: judging whether the impedance parameter corresponding to the frequency modulation frequency in the searching process reaches an extreme value or not. If yes, executing S204; if not, S203f is performed.

It should be noted that the searching process in this step refers to a searching process in all pulse periods from the first searching of the ith pulse period to the current time.

S203f: updating the value of i according to i=i+k, taking the second frequency modulation frequency as the second initial frequency of the first radio frequency power stage of the i+k pulse period, and returning to execute S203d.

As an example, the plurality of pulse periods located after the i-th pulse period may be a plurality of consecutive pulse periods adjacent to the i-th pulse period. As another example, the plurality of pulse periods located after the i-th pulse period may also be a plurality of pulse periods spaced apart from the i-th pulse period by at least one pulse period and spaced apart therebetween by at least one pulse period.

Wherein, when a plurality of pulse periods located after the ith pulse period may be a plurality of continuous pulse periods adjacent to the ith pulse period, the plurality of pulse periods may be the (i+1) th pulse period, the (i+2) th pulse period, the … … th and the (i+m) th pulse periods, wherein i+m is less than or equal to n, and m is a positive integer.

For convenience of explanation and explanation, the i-th pulse period will be exemplified as the 1-th pulse period. The pulse periods after the 1 st pulse period may be the 2 nd pulse period, the 3 rd pulse period, the … … th pulse period, and the t th pulse period, where t is less than or equal to n, and t is a positive integer.

When the plurality of pulse periods located after the ith pulse period may be a plurality of pulse periods spaced apart from the ith pulse period by at least one pulse period and spaced apart therefrom by at least one pulse period, the plurality of pulse periods may be the (i+k) th pulse period, the (i+2k) th pulse period, the … … th and the (i+nk) th pulse periods, wherein i+nk is equal to or less than n, and k is a positive integer.

For convenience of explanation and explanation, the following will be described by taking the i-th pulse period as the 1-th pulse period and taking the interval of one pulse period as an example. The pulse periods positioned after the 1 st pulse period can be the 3 rd pulse period, the 5 th pulse period, the … … th pulse period and the 2K-1 st pulse period, wherein, 2K-1 is less than or equal to n, and K is a positive integer.

In this embodiment of the present application, the impedance parameter may be reflected power, a reflection coefficient, or an impedance. When the impedance parameters are different, the nonlinear functional relationship between the impedance parameters and the RF radio frequency may have a maximum value or a minimum value, and accordingly, the extremum of the impedance parameters may be a minimum value or a maximum value. For example, when the impedance parameter is reflected power, the extremum of the impedance parameter is a minimum value.

In addition, in the embodiment of the present application, the specific fm frequencies may be different frequency values in the process of searching for a matching frequency. As an example, the specific fm frequency may be a matching frequency that matches the plasma and plasma impedance that is found during the first rf power phase of the pulse period in which it is located. As another example, a particular fm frequency is one that is randomly read during a search for a matching frequency in the first rf power phase of the pulse period in which it is located.

S204: and determining the corresponding radio frequency when the impedance parameter reaches the extreme value as the matching frequency of the first radio frequency power stage of the pulse radio frequency power and the plasma impedance.

The above is an implementation manner of the impedance matching method of the pulsed radio frequency plasma provided in the embodiments of the present application. In the implementation manner, first initial frequency in a first radio frequency power stage of an ith pulse period is obtained, then matching frequency is continuously searched in the first radio frequency power stage of the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period according to the first initial frequency until an impedance parameter corresponding to the searched frequency modulation frequency reaches an extremum, and finally the radio frequency corresponding to the impedance parameter reaching the extremum is determined as the matching frequency of the first radio frequency power stage of the pulse radio frequency power and the plasma impedance.

In the process of searching the matching frequency in the ith pulse period and the first radio frequency power stage of the plurality of pulse periods positioned behind the ith pulse period, the specific allocation frequency read in the process of searching the matching frequency of the previous pulse is given to the next pulse and is used as the initial frequency of the next pulse, so that the rate of generating frequency by the power generator can be compensated to be unable to keep pace with the adjustment rate of the frequency modulation frequency, the allocation mode is equivalent to increasing the width of the first radio frequency power stage of one pulse period, and therefore, the matching frequency of the pulse radio frequency plasma with higher pulse frequency can be searched through continuous frequency modulation of the first radio frequency power stage of the plurality of pulses, thereby the impedance matching of the plasma is not limited to be completed in a single pulse, and the impedance matching of the plasma with higher pulse frequency is realized.

Moreover, in this implementation, the first rf power stage may be a high rf power stage or a low rf power stage. Therefore, in the implementation mode, different initial frequencies can be set in a high radio frequency power stage and a low radio frequency power stage, and frequency modulation matching can be independently carried out, so that the frequency hopping of a large range in the high power stage and the low power stage can be realized.

In order to more clearly understand the specific embodiments of the present application, a process of matching a matching frequency with a plasma impedance during a high rf power stage is described below as an example. In the following embodiments, the impedance parameter is described by taking reflected power as an example.

Three specific embodiments of the impedance matching method of the pulsed rf plasma provided in the embodiments of the present application will be described in sequence.

An implementation manner of the impedance matching method of the pulsed rf plasma provided in the embodiment of the present application will be specifically described below with reference to fig. 4 and 5. Fig. 4 is a flowchart of an implementation manner of an impedance matching method of a pulsed rf plasma according to an embodiment of the present application; fig. 5 is a schematic diagram of an implementation manner of an impedance matching method of a pulsed rf plasma according to an embodiment of the present application.

The impedance matching method of the pulse radio frequency plasma provided by the embodiment of the application can be specifically as follows:

s401: pulsed radio frequency power is provided to the plasma reaction chamber.

By way of example, the pulsed radio frequency power may be pulsed radio frequency power 501 provided in fig. 5.

S402: acquisition of initial frequency f in high RF power phase of 1 st pulse period ₀ (h)。

As an example, the initial frequency f ₀ (h) May be f of the RF radio frequency 502 provided in FIG. 5 ₀ (h) Frequency.

S403: according to the initial frequency f ₀ (h) Searching for a matching frequency f in the high RF power phase of the 1 st pulse period ₁ (h)。

Wherein the matching frequency f ₁ (h) May be a matching frequency found to match the plasma impedance during the high rf power phase of pulse 1.

As an example, S403 may specifically be:

s403a: searching for matching frequency in the high RF power stage of the 1 st pulse period, and frequency modulating for multiple times during searching.

As an example, in the 1 st pulse period provided in fig. 5, the RF frequency is tuned 3 times, where the tuning frequency is in turn f ₁₁ (h)、f ₁₂ (h) And f ₁₃ (h)。

S403b: in the high RF power stage of the 1 st pulse period, selecting the FM frequency for making the reflected power reach the minimum value as the matching frequency f ₁ (h)。

The reflected power varies with the frequency modulation frequency, different frequency modulation frequencies corresponding to different reflected powers.

For example, the value of reflected power 503 provided in fig. 5 varies with the RF frequency. And when the frequency modulation frequency is f ₁₁ (h) At the time, the reflected power is P ₁ The method comprises the steps of carrying out a first treatment on the surface of the When the frequency modulation frequency is f ₁₂ (h) At the time, the reflected power is P ₂ The method comprises the steps of carrying out a first treatment on the surface of the When the frequency modulation frequency is f ₁₃ (h) At the time, the reflected power is P ₃ 。

As an example, S403b may specifically be: in FIG. 5, if the frequency is f ₁₂ (h) Corresponding reflected power P ₂ When the frequency is minimum, the frequency modulation frequency f ₁₂ (h) Matching power f in the high RF power phase as pulse period 1 ₁ (h)。

It should be noted that, in the embodiment of the present application, the matching frequency is obtained by using the above method in each pulse period.

S404: reading and saving the matching frequency f obtained in the high RF power phase of the 1 st pulse period ₁ (h)。

S405: and judging whether the reflection power values corresponding to the plurality of frequency modulation frequencies in the searching process reach the minimum value or not. If yes, then execute S40E; if not, S406 is performed.

S406: will match the frequency f ₁ (h) As an initial frequency in the high rf power phase of pulse 2.

S407: according to the initial frequency f ₁ (h) The matching frequency is searched for during the high rf power phase of pulse 2.

S408: reading and saving the matching frequency f obtained in the high RF power phase of the 2 nd pulse period ₂ (h)。

S409: and judging whether the reflection power values corresponding to the plurality of frequency modulation frequencies in the searching process reach the minimum value or not. If yes, then execute S40E; if not, S410 is performed.

It should be noted that the searching process in this step includes searching processes of the 1 st pulse period and the 2 nd pulse period.

S410: will match the frequency f ₂ (h) As an initial frequency in the high rf power phase of the 3 rd pulse period.

And so on, when the reflected power corresponding to the matching frequency read in the high rf power stage of the previous pulse period does not reach the minimum value, repeating the steps of searching the matching frequency in the high rf power stage of the previous pulse period as the initial frequency in the high rf power stage of the next pulse period adjacent thereto, and searching the matching frequency in the high rf power stage of the next pulse period adjacent thereto until the reflected power corresponding to the read matching frequency reaches the minimum value, and ending the cycle, and S40E may be executed.

S40E: and determining the corresponding radio frequency when the reflection power value reaches the minimum value as the matching frequency of the high radio frequency power stage of the pulse radio frequency power and the plasma impedance.

In the impedance matching method of the pulsed rf plasma provided in the embodiment of the present application, the matching frequency is continuously searched in the i-th pulse period and the high rf power phase of the adjacent multiple pulse periods located behind the i-th pulse period, the matching frequency searched in the process of searching the matching frequency is given to the next pulse, and is used as the initial frequency of the next pulse, so that the width of the high rf power phase of one pulse period is increased, and the matching frequency of the pulsed rf plasma with the higher pulse frequency can be searched through continuous frequency modulation of the first rf power phase of the multiple pulses, so that impedance matching of the plasma is not limited to be completed in a single pulse, and impedance matching of the plasma with the higher pulse frequency is further realized.

In addition, the specific implementation mode takes the matching frequency of the high radio frequency power stage of the previous pulse as the initial frequency modulation frequency of the next pulse, so that the frequency modulation frequency can be reduced, and the frequency modulation efficiency can be improved.

In the above-provided embodiment, the specific tuning frequency in the process of searching the matching frequency in the high rf power stage of each pulse period is the matching frequency matched with the plasma impedance searched in the high rf power stage of the pulse period where the specific tuning frequency is located, and the pulse period adopted in the tuning process is exemplified as a continuous pulse period.

As an extension of the embodiment of the present application, the specific fm frequencies in the process of searching the matching frequencies in the high rf power stage of each pulse period may also be randomly read fm frequencies in the process of searching the matching frequencies in the high rf power stage of the pulse period, which will be specifically described and illustrated below.

Another implementation of the impedance matching method of the pulsed rf plasma provided in the embodiments of the present application will be specifically described below with reference to fig. 6 and 7. Fig. 6 is a flowchart of another implementation of the impedance matching method of the pulsed rf plasma provided in the embodiment of the present application; fig. 7 is a schematic diagram of another implementation of the impedance matching method of the pulsed rf plasma provided in the embodiment of the present application.

s601: pulsed radio frequency power is provided to the plasma reaction chamber.

As an example, the pulsed radio frequency power may be pulsed radio frequency power 701 provided in fig. 7.

S602: acquisition of initial frequency f in high RF power phase of 1 st pulse period ₀ (h)。

As an example, the initial frequency f ₀ (h) May be f of the RF radio frequency 702 provided in FIG. 7 ₀ (h) Frequency.

S603: according to the initial frequency f ₀ (h) The matching frequency is searched for during the high rf power phase of the 1 st pulse period.

S604: randomly reading and storing the FM frequency f in the process of searching the matching frequency in the high radio frequency power stage of the 1 st pulse period ₁ (h)。

As an example, in the 1 st pulse period provided in fig. 7, the RF frequency is tuned 3 times, where the tuning frequency is in turn f ₁₁ (h)、f ₁₂ (h) And f ₁₃ (h) S604 may specifically be: the frequency modulation frequency read randomly can be f ₁₁ (h)、f ₁₂ (h) And f ₁₃ (h) Any one of them.

It should be noted that, in the embodiment of the present application, the above method is used to read the fm frequency in each pulse period.

S605: judging the frequency modulation frequency f in the searching process ₁ (h) Whether the corresponding reflection power value reaches a minimum value. If yes, then execute S60E; if not, S606 is performed.

S606: frequency modulation frequency f to be read randomly ₁ (h) As an initial frequency in the high rf power phase of pulse 2.

S607: according to the initial frequency f ₁ (h) Searching for matching frequency in the high RF power stage of the 2 nd pulse period, and frequency modulating for multiple times during searching.

S608: randomly reading and storing the FM frequency f in the process of searching the matching frequency in the high radio frequency power stage of the 2 nd pulse period ₂ (h)。

S609: and judging whether the reflection power value corresponding to the frequency modulation frequency in the searching process reaches a minimum value or not. If yes, then execute S60E; if not, S610 is performed.

S610: frequency modulation frequency f to be read randomly ₂ (h) As an initial frequency in the high rf power phase of the 3 rd pulse period.

And so on, when the reflected power corresponding to the fm frequency in the process of searching the matching frequency in the high rf power stage of the previous pulse period does not reach the minimum value, repeating the steps of taking the fm frequency randomly read in the high rf power stage of the previous pulse period as the initial frequency in the high rf power stage of the next pulse period adjacent thereto, and searching the matching frequency in the high rf power stage of the next pulse period adjacent thereto until the reflected power corresponding to the fm frequency in the process of searching the matching frequency reaches the minimum value, ending the cycle, and executing S60E.

S60E: and determining the corresponding radio frequency when the reflection power value reaches the minimum value as the matching frequency of the high radio frequency power stage of the pulse radio frequency power and the plasma impedance.

The present embodiments provide for another different implementation of an impedance matching method for pulsed radio frequency plasma. In this embodiment, the specific fm frequencies during the high rf power phase of each pulse period search for the matching frequencies are randomly read fm frequencies during the high rf power phase of the pulse period in which they are located. In the method, the matching frequency of the pulse radio frequency plasma with higher pulse frequency can be searched through continuously searching the matching frequency in the i-th pulse period and the high radio frequency power stages of a plurality of pulse periods positioned behind the i-th pulse period, the allocated frequency randomly read by the previous pulse in the process of searching the matching frequency is given to the next pulse and is used as the initial frequency of the next pulse, so that the width of the high radio frequency power stage of one pulse period is increased, and the matching frequency of the pulse radio frequency plasma with higher pulse frequency can be searched through continuous frequency modulation of the high radio frequency power stages of the plurality of pulses, and the impedance matching of the plasma with higher pulse frequency is realized.

In the two embodiments provided above, the plurality of pulse periods used for frequency modulation are exemplified as a plurality of consecutive pulse periods. In practice, the plurality of pulse periods used for the frequency modulation may be discontinuous. The plurality of pulse periods may be a plurality of pulse periods separated by at least one pulse period.

When the pulse periods are discontinuous, the pulse rf power including n pulse periods may be divided into a plurality of rf frequency modulation paths in advance, and impedance matching may be performed on the pulse rf plasma in each rf frequency modulation path, so as to obtain a matching frequency in each rf frequency modulation path, which is matched with the plasma impedance.

For ease of explanation and explanation, the following description will specifically describe and explain taking the division into two rf fm paths as an example.

A further implementation of the impedance matching method of the pulsed rf plasma provided in the embodiments of the present application will be specifically described with reference to fig. 8 and 9. Fig. 8 is a flowchart of another implementation of the impedance matching method of the pulsed rf plasma provided in the embodiment of the present application; fig. 9 is a schematic diagram of still another implementation manner of an impedance matching method of a pulsed rf plasma according to an embodiment of the present application.

s801: pulsed radio frequency power is provided to the plasma reaction chamber.

By way of example, the pulsed radio frequency power may be pulsed radio frequency power 901 provided in fig. 9.

S802: acquisition of initial frequency f in high RF power phase of 1 st pulse period ₀ (h)。

Initial frequency f ₀ (h) The frequency may be manually assigned or may be previously auto-tuned.

As an example, the initial frequency f ₀ (h) May be f of the RF radio frequency 902 provided in fig. 9 ₀ (h) Frequency.

S803: acquisition of initial frequency F in high RF power phase of pulse period 2 ₀ (h)。

As an example, an initial frequency F ₀ (h) May be the F of the RF radio frequency 902 provided in fig. 9 ₀ (h) Frequency.

In the embodiment of the present application, the initial frequency f ₀ (h) And an initial frequency F ₀ (h) May be equal or unequal.

S804: according to the initial frequency f ₀ (h) A first matching frequency is obtained.

The specific implementation of this step will be described in detail below.

S805: according to the initial frequency F ₀ (h) A second matching frequency is obtained.

The specific implementation of this step will be described in detail below.

It should be noted that, in the embodiment of the present application, S802 and S803 are not in sequence, and S802 may be executed first and then S803 may be executed. S803 may be executed first, and S802 may be executed next. Moreover, S804 and S805 have no sequence, S804 may be executed first, and S805 may be executed second. S805 may be executed first, and S804 may be executed later.

Specific embodiments of S804, S805, and S806 will be described in order.

The specific embodiment of S804 is as follows:

referring to fig. 10, a flowchart of a method for acquiring a first matching frequency according to an embodiment of the present application is shown.

As an example, S804 may specifically be:

s8041: according to the initial frequency f ₀ (h) Searching for a matching frequency f in the high RF power phase of the 1 st pulse period ₁ (h)。

It should be noted that in the embodiment of the present application, the same method is used to search for a matching frequency in each pulse period.

S8042: reading and saving the matching frequency f in the high RF power phase of the 1 st pulse period ₁ (h)。

S8043: and judging whether the reflection power values corresponding to the plurality of frequency modulation frequencies in the searching process reach the minimum value or not. If yes, then execute S804E; if not, S8044 is performed.

Wherein the reflected power may be reflected power 903 provided in fig. 9.

S8044: will match the frequency f ₁ (h) As an initial frequency in the high rf power phase of the 3 rd pulse period.

S8045: according to the initial frequency f ₁ (h) The matching frequency is searched for during the high rf power phase of pulse 3.

S8046: reading and saving the matching frequency f in the high RF power phase of the 3 rd pulse period ₂ (h)。

S8047: and judging whether the reflection power values corresponding to the plurality of frequency modulation frequencies in the searching process reach the minimum value or not. If yes, then execute S804E; if not, S8048 is performed.

S8048: will match the frequency f ₂ (h) As an initial frequency in the high rf power phase of the 5 th pulse period.

And so on, when the reflected power corresponding to the matching frequency read in the high rf power stage of the previous pulse period does not reach the minimum value, repeating the steps of searching the matching frequency in the high rf power stage of the previous pulse period as the initial frequency in the high rf power stage of the next pulse period spaced by one pulse period, and searching the matching frequency in the high rf power stage of the next pulse period spaced by one pulse period until the reflected power corresponding to the searched frequency modulation frequency reaches the minimum value, and ending the cycle, and then S804E may be executed.

S804E: and determining the corresponding radio frequency when the reflection power value reaches the minimum value as a first matching frequency for matching the high radio frequency power stage of the pulse radio frequency power with the plasma impedance.

The above is a specific embodiment of S804. In S804, a first matching frequency to match the plasma impedance for a high rf power phase of the pulsed rf power may be obtained using a plurality of consecutive odd-numbered pulse periods.

In the specific embodiment of S804, the initial frequency in the high rf power phase assigned to the next pulse period is described by taking the matching frequency in the high rf power phase of the previous pulse period as an example. In practice, the initial frequency in the high rf power phase assigned to the next pulse period may also be a frequency randomly read during the search match in the high rf power phase of the previous pulse period. This implementation is similar to the implementation shown in fig. 6 and will not be described in detail here for brevity.

The specific embodiment of S805 is as follows:

referring to fig. 11, the flowchart of a method for acquiring the second matching frequency according to the embodiment of the present application is shown.

As an example, S805 may specifically be:

s8051: according to the initial frequency F ₀ (h) Searching for a matching frequency F in the high RF power phase of the 2 nd pulse period ₁ (h)。

S8052: reading and saving the matching frequency F obtained in the high RF power phase of the 2 nd pulse period ₁ (h)。

S8053: and judging whether the reflection power values corresponding to the plurality of frequency modulation frequencies in the searching process reach the minimum value or not. If yes, then execute S805E; if not, S8054 is performed.

S8054: will match the frequency F ₁ (h) As an initial frequency in the high rf power phase of the 4 th pulse period.

S8055: according to the initial frequency F ₁ (h) The matching frequency is searched for during the high rf power phase of the 4 th pulse period.

S8056: reading and saving the matching frequency F in the high RF power phase of the 4 th pulse period ₂ (h)。

S8057: and judging whether the reflection power values corresponding to the plurality of frequency modulation frequencies in the searching process reach the minimum value or not. If yes, then execute S805E; if not, S8058 is performed.

S8058: will match the frequency F ₂ (h) As an initial frequency in the high rf power phase of the 6 th pulse period.

And so on, when the reflected power corresponding to the matching frequency read in the high rf power stage of the previous pulse period does not reach the minimum value, repeating the steps of searching the matching frequency in the high rf power stage of the previous pulse period as the initial frequency in the high rf power stage of the next pulse period spaced by one pulse period therefrom, and searching the matching frequency in the high rf power stage of the next pulse period spaced by one pulse period until the reflected power corresponding to the read matching frequency reaches the minimum value, and ending the cycle, and S805E may be executed.

S805E: and determining the corresponding radio frequency when the reflection power value reaches the minimum value as a second matching frequency for matching the high radio frequency power stage of the pulse radio frequency power with the plasma impedance.

The above is a specific embodiment of S805. In S805, a second matching frequency to match the plasma impedance for a high rf power phase of the pulsed rf power may be obtained with a plurality of consecutive even-numbered pulse periods.

In this embodiment, two rf tuning paths are provided, and the final result is determined by the tuning results of the two rf tuning paths. In fact, as an extension of the embodiment of the present application, frequency modulation matching may be performed only according to one of the rf frequency modulation paths, so as to finally obtain a matching frequency matched with the plasma impedance in the high rf power stage of the pulsed rf power.

In addition, in the above embodiment, the plurality of pulse periods used for each rf frequency modulation path are also discontinuous ones, and the discontinuous ones are ones separated by one pulse period. In fact, as an extension of the embodiment of the present application, 3 or more rf frequency modulation paths may be further provided, where the multiple pulse periods used in each rf frequency modulation path are discontinuous multiple pulse periods, and the discontinuous multiple pulse periods are multiple pulse periods separated by two or more pulse periods. The specific implementation of setting 3 or more rf fm paths is similar to the above-described implementation, and will not be repeated here.

In the impedance matching method of the pulsed rf plasma provided in the embodiment of the present application, the matching frequency is continuously searched in the i-th pulse period and the first rf power stage of the multiple pulse periods located at least one pulse period after the i-th pulse period, the specific allocation frequency read by the previous pulse in the process of searching the matching frequency is assigned to the next pulse, and the next pulse is used as the initial frequency of the next pulse, so that the width of the first rf power stage of one pulse period is increased, and the matching frequency of the pulsed rf plasma with the higher pulse frequency can be searched through continuous frequency modulation of the first rf power stage of the multiple pulses, thereby realizing impedance matching of the plasma with the higher pulse frequency.

In the three embodiments provided above, the specific frequency modulation frequency of one pulse period is taken as the initial frequency of another pulse period, so that the other pulse period can be further subjected to frequency adjustment based on the initial frequency. In addition, in order to further improve the accuracy of the matching frequency, the method can further adjust the frequency by taking the specific frequency of the radio frequency modulation section including at least one pulse period as the initial frequency of another radio frequency modulation section, so that the other radio frequency modulation section can further adjust the frequency based on the initial frequency.

The radio frequency modulation intervals are obtained by dividing n pulse periods, and each radio frequency modulation interval comprises at least one pulse period.

For ease of explanation and explanation, the radio frequency modulation section will be explained and explained with reference to the drawings.

Referring to fig. 12a, a schematic diagram of an embodiment of dividing pulsed rf power into a plurality of rf frequency modulation intervals is provided in the application example.

As an embodiment, as shown in fig. 12a, when the pulsed rf power includes n pulse periods, the rf frequency modulation interval may be divided equally by the n pulse periods, so as to obtain K adjacent rf frequency modulation intervals. At this time, each rf fm interval includes 2 pulse periods.

Referring to fig. 12b, a schematic diagram of another embodiment of dividing pulsed rf power into multiple rf frequency modulation intervals is provided in the application example.

As another embodiment, as shown in fig. 12b, when the pulsed rf power includes n pulse periods, the rf frequency modulation interval may be randomly divided by the n pulse periods, so as to obtain K adjacent rf frequency modulation intervals. At this time, the different rf intervals have different numbers of pulse periods, for example, the first rf interval includes 2 pulse periods, the second rf interval includes 4 pulse periods, and the kth rf interval includes 6 pulse periods.

Based on the radio frequency modulation interval provided by the above, the application also provides a method for adjusting the frequency based on the radio frequency modulation interval. The following is a description and is made with reference to the accompanying drawings.

Referring to fig. 13, a flowchart of another implementation of the impedance matching method of the pulsed rf plasma provided in the embodiments of the present application is shown.

s1301: dividing the pulse radio frequency power comprising n pulse periods into K adjacent radio frequency modulation intervals, wherein each radio frequency modulation interval comprises at least one pulse period; the pulse period includes a first radio frequency power phase; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer, K is ∈ 2, and K is a positive integer.

S1302: and acquiring a first initial frequency of a kth radio frequency modulation interval, wherein K is less than K and is a positive integer.

The kth rf interval may be any one of the 1 st rf interval to the K-1 st rf interval.

As an example, the embodiment of the present application may take the 1 st rf interval as the kth rf interval as an example.

S1303: searching matching frequencies in the kth radio frequency modulation interval and each pulse period in a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval continuously according to the first initial frequency until impedance parameters corresponding to the searched frequency modulation frequencies reach an extremum, and reading specific frequency modulation frequencies in the process of searching the matching frequencies in the first radio frequency power stage of each pulse period of each radio frequency modulation interval in the process of searching the matching frequencies in the first radio frequency power stage of each radio frequency modulation interval; in the kth rf frequency modulation interval and a plurality of subsequent rf frequency modulation intervals, the specific frequency modulation frequency of the first rf power stage of the preceding rf frequency modulation interval of two adjacent rf frequency modulation intervals is used as the initial frequency of the first rf power stage of the subsequent rf frequency modulation interval.

As an example, S1303 may specifically be:

s13031: searching for a matching frequency in a first radio frequency power stage of each pulse period of a kth radio frequency modulation interval according to the first initial frequency, reading and storing a specific frequency modulation frequency, and recording the specific frequency modulation frequency as the frequency modulation frequency of the first interval.

The process of searching for the matching frequency may specifically be: according to any one of the impedance matching methods for pulsed rf plasma provided in the foregoing embodiments, a matching frequency of the plasma impedance in the first rf power stage of the pulsed rf power in the kth rf frequency modulation interval is obtained, and the matching frequency is used as a characteristic frequency modulation frequency.

S13032: judging whether impedance parameters corresponding to a plurality of radio frequency modulation intervals in the searching process reach an extreme value or not. If yes, then execution S1304; if not, then S13033 is performed.

S13033: assigning the frequency modulation frequency of the first interval to a first radio frequency power stage of the k+m radio frequency modulation interval, and taking the first radio frequency power stage as a second initial frequency of the first radio frequency power stage of the k+m radio frequency modulation interval; k+m is less than or equal to K, and m is a positive integer.

S13034: searching for matching frequency in the first radio frequency power stage of each pulse period of the k+m radio frequency modulation interval according to the second initial frequency, reading and storing the specific frequency modulation frequency, and recording the specific frequency modulation frequency as the frequency modulation frequency of the second interval.

It should be noted that the process of searching for the matching frequency is the same as the process of searching for the matching frequency in S13031, and will not be described in detail here for brevity.

S13035: judging whether impedance parameters corresponding to a plurality of radio frequency modulation intervals in the searching process reach an extreme value or not. If yes, then execution S1304; if not, S13036 is executed.

It should be noted that the searching process in this step refers to a searching process in all pulse periods from the first searching in the kth rf fm interval to the current time.

S13036: and updating the k value according to k=k+m, taking the frequency modulation frequency of the second interval as the second initial frequency of the first radio frequency power stage of the k+m radio frequency modulation interval, and returning to execute S13034.

As an example, the plurality of radio frequency intervals located after the kth radio frequency interval may be a plurality of consecutive radio frequency intervals adjacent to the kth radio frequency interval. As another example, the plurality of radio frequency intervals located after the kth radio frequency interval may be a plurality of radio frequency intervals spaced from the kth radio frequency interval by at least one radio frequency interval and spaced therebetween by at least one radio frequency interval.

When a plurality of radio frequency intervals following the kth radio frequency interval may be a plurality of continuous radio frequency intervals adjacent to the kth radio frequency interval, the plurality of radio frequency intervals may be a k+1th radio frequency interval, a k+2th radio frequency interval, … …, a k+s radio frequency interval, where k+s is less than or equal to K, and s is a positive integer.

For convenience of explanation and explanation, the following will be an example in which the kth rf interval is the 1 st rf interval. The plurality of radio frequency modulation intervals located behind the 1 st radio frequency modulation interval can be a 2 nd radio frequency modulation interval, a 3 rd radio frequency modulation interval, a … … th radio frequency modulation interval and a z-th radio frequency modulation interval, wherein z is less than or equal to K, and z is a positive integer.

When the plurality of radio frequency intervals located behind the kth radio frequency interval may be a plurality of radio frequency intervals spaced from the kth radio frequency interval by at least one radio frequency interval, and the intervals therebetween are at least one radio frequency interval, the plurality of radio frequency intervals may be a kth+mradio frequency interval, a kth+2mradio frequency interval, … …, a kth+Nm radio frequency interval, where k+Nm is less than or equal to K, and m is a positive integer.

For ease of explanation and explanation, the following description will take the kth rf interval as the 1 st rf interval and take the interval of one rf interval as an example. The plurality of radio frequency modulation intervals positioned behind the 1 st radio frequency modulation interval can be a 3 rd radio frequency modulation interval, a 5 th radio frequency modulation interval, a … … th radio frequency modulation interval and a 2M-1 st radio frequency modulation interval, wherein 2M-1 is less than or equal to K, and M is a positive integer.

S1304: and determining the corresponding radio frequency when the impedance parameter reaches the extreme value as the matching frequency of the first radio frequency power stage of the pulse radio frequency power and the plasma impedance.

The above is an implementation manner of the impedance matching method of the pulsed radio frequency plasma provided in the embodiments of the present application. In the implementation mode, firstly, pulse radio frequency power comprising n pulse periods is divided into K adjacent radio frequency modulation intervals, secondly, a first initial frequency of a kth radio frequency modulation interval is obtained, then, a matching frequency is continuously searched in the kth radio frequency modulation interval and each pulse period in a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval according to the first initial frequency until impedance parameters corresponding to the searched frequency modulation frequency reach an extremum, and finally, the radio frequency corresponding to the impedance parameters reaching the extremum is determined as the matching frequency of a first radio frequency power stage of the pulse radio frequency power and plasma impedance.

In addition, in the process of searching the matching frequency in the first radio frequency power stage of each pulse period of each radio frequency modulation section, the specific frequency modulation frequency read in the process of searching the matching frequency in the first radio frequency power stage of the previous radio frequency modulation section is assigned to the next radio frequency modulation section and is used as the initial frequency of the next radio frequency modulation section, so that the rate of the generated frequency of the power generator can be further compensated to be unable to keep up with the adjustment rate of the frequency modulation frequency.

The explanation and explanation will be made with reference to fig. 14 and 15. Fig. 14 is a flowchart of an implementation manner of an impedance matching method of a pulsed rf plasma provided by an embodiment of the present application, and fig. 15 is a schematic diagram of an implementation manner of an impedance matching method of a pulsed rf plasma provided by an embodiment of the present application.

s1401: pulsed radio frequency power is provided to the plasma reaction chamber.

As an example, the pulsed radio frequency power may be pulsed radio frequency power 1501 in fig. 15.

S1402: dividing the pulsed radio frequency power into K adjacent radio frequency modulation intervals: the 1 st radio frequency modulation interval, the 2 nd radio frequency modulation interval, … …, the K-th radio frequency modulation interval.

S1403: obtaining the initial frequency f of the 1 st radio frequency modulation interval ₀ (h)。

As an example, initially Initial frequency f ₀ (h) May be f of the RF frequency 1502 provided in FIG. 15 ₀ (h) Frequency.

S1404: according to the initial frequency f ₀ (h) Searching for a matching frequency f in the high RF power phase of the 1 st RF frequency modulation interval ₁ (h)。

As an implementation manner, S1404 may obtain the matching frequency f of the high rf power stage in the 1 st rf frequency modulation section by using any of the impedance matching methods of the pulsed rf plasma provided in the above embodiments ₁ (h)。

S1405: reading and storing the matching frequency f obtained in the high RF power stage of the 1 st RF frequency modulation interval ₁ (h)。

S1406: and judging whether the reflection power values corresponding to the plurality of frequency modulation frequencies in the searching process reach the minimum value or not. If yes, then S140E is performed; if not, S1407 is performed.

S1407: will match the frequency f ₁ (h) As an initial frequency in the high rf power phase of the 2 nd rf frequency modulation interval.

S1408: according to the initial frequency f ₁ (h) Searching for a matching frequency f in the high RF power phase of the 2 nd RF frequency modulation interval ₂ (h)。

S1409: reading and storing the matching frequency f obtained in the high RF power stage of the 2 nd RF frequency modulation interval ₂ (h)。

S1410: and judging whether the reflection power values corresponding to the plurality of frequency modulation frequencies in the searching process reach the minimum value or not. If yes, then S140E is performed; if not, S1411 is performed.

It should be noted that the searching process in this step includes the searching process of the 1 st rf frequency modulation interval and the 2 nd rf frequency modulation interval.

S1411: will match the frequency f ₂ (h) As an initial frequency in the high rf power phase of the 3 rd rf interval.

And so on, when the reflected power corresponding to the matching frequency read in the high rf power stage of the previous rf frequency modulation section does not reach the minimum value, repeating the steps of searching the matching frequency in the high rf power stage of the previous rf frequency modulation section as the initial frequency in the high rf power stage of the next adjacent rf frequency modulation section, searching the matching frequency in the high rf power stage of the next adjacent rf frequency modulation section until the reflected power corresponding to the read matching frequency reaches the minimum value, and ending the cycle, and executing S140E.

S140E: and determining the corresponding radio frequency when the reflection power value reaches the minimum value as the matching frequency of the high radio frequency power stage of the pulse radio frequency power and the plasma impedance.

In the impedance matching method for pulsed rf plasma provided in the embodiment of the present invention, the matching frequency is continuously searched in the high rf power stage of the kth rf frequency modulation section and the adjacent rf frequency modulation sections located behind the kth rf frequency modulation section, the matching frequency searched in the process of searching the matching frequency in the previous rf frequency modulation section is given to the next rf frequency modulation section, and is used as the initial frequency of the next rf frequency modulation section, so that the widths of the multiple high rf power stages in one rf frequency modulation section are increased, and thus, the matching frequency of pulsed rf plasma with higher pulse frequency can be searched through continuous frequency modulation of the first rf power stage of the multiple rf frequency modulation sections, so that impedance matching of plasma is not limited to be completed in a single rf frequency modulation section, and impedance matching of plasma with higher pulse frequency is further realized.

In addition, the specific implementation mode takes the matching frequency of the high radio frequency power stage of the previous radio frequency modulation interval as the initial frequency modulation frequency of the next radio frequency modulation interval, so that the frequency modulation frequency can be reduced, and the frequency modulation efficiency can be improved.

In the above-provided embodiments, the plurality of radio frequency modulation sections used for modulation are exemplified as a plurality of consecutive radio frequency modulation sections. In practice, the plurality of radio frequency intervals used for frequency modulation may be discontinuous ones. The plurality of rf intervals may be a plurality of rf intervals separated by at least one pulse period.

Based on the impedance matching method of the pulsed rf plasma provided by the foregoing embodiments, the embodiments of the present application further provide an impedance matching device of the pulsed rf plasma, and the impedance matching device of the pulsed rf plasma provided by the embodiments of the present application may adopt various embodiments, which will be explained and illustrated in the following sequence with reference to the accompanying drawings.

Referring to fig. 16, a schematic structural diagram of an implementation manner of an impedance matching device for pulsed rf plasma according to an embodiment of the present application is shown.

As an implementation manner, as shown in fig. 16, an impedance matching device for pulsed radio frequency plasma provided in the embodiment of the present application includes:

A supply unit 1601 configured to supply pulsed rf power to the plasma reaction chamber, the pulsed rf power comprising n pulse periods, each pulse period comprising a first rf power stage; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer;

an acquisition unit 1602, configured to acquire a first initial frequency in a first rf power phase of an i-th pulse period; i < n, and i is a positive integer;

a searching unit 1603, configured to continuously search for a matching frequency in the i-th pulse period and a first rf power stage of a plurality of pulse periods located behind the i-th pulse period according to the first initial frequency until an impedance parameter corresponding to the searched frequency reaches an extremum, and read a specific frequency modulation frequency in the process of searching for the matching frequency in the first rf power stage of each pulse period; wherein, in the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period, the specific frequency modulation frequency of the first radio frequency power stage of the previous pulse period of the two adjacent pulse periods is used as the initial frequency of the first radio frequency power stage of the next pulse period;

The determining unit 1604 is configured to determine a radio frequency corresponding to the case where the impedance parameter reaches the extremum as a matching frequency of the first radio frequency power stage of the pulsed radio frequency power and the plasma impedance.

The impedance matching device for pulsed radio frequency plasma provided by the embodiment of the application comprises: a providing unit 1601, an acquiring unit 1602, a searching unit 1603, and a determining unit 1604. In the device, first initial frequency in a first radio frequency power stage of an ith pulse period is firstly obtained, then matching frequency is continuously searched in the first radio frequency power stage of the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period according to the first initial frequency until impedance parameters corresponding to the searched frequency modulation frequency reach an extremum, and finally the radio frequency corresponding to the impedance parameters reaching the extremum is determined as the matching frequency of the first radio frequency power stage of the pulse radio frequency power and plasma impedance.

In the embodiments provided above, the plurality of pulse periods used for frequency modulation are a plurality of consecutive pulse periods. In addition, the pulse periods used for frequency modulation can also be discontinuous pulse periods. The plurality of pulse periods may be a plurality of pulse periods separated by at least one pulse period.

Thus, the present embodiments also provide another implementation of an impedance matching device for pulsed rf plasma, as will be explained and illustrated below with reference to the accompanying drawings.

Referring to fig. 17, a schematic structural diagram of another implementation manner of an impedance matching device for pulsed rf plasma according to an embodiment of the present application is shown.

As an implementation manner, as shown in fig. 17, an impedance matching device for pulsed radio frequency plasma provided in the embodiment of the present application includes:

A dividing unit 1701, configured to divide a pulsed rf power including n pulse periods into a plurality of rf frequency modulation paths in advance, where each rf frequency modulation path includes at least two non-adjacent pulse periods; each pulse period includes a first radio frequency power phase; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer;

an impedance matching unit 1702 configured to perform impedance matching on the pulsed rf plasma in each rf frequency modulation path;

the impedance matching unit 1702 specifically includes:

an obtaining unit 17021, configured to obtain a first initial frequency in a first rf power phase of a j-th pulse period in an rf fm path; setting the number of pulse periods included in the impedance radio frequency modulation path as m, wherein m is less than n, j is less than m, and j and m are positive integers;

a searching unit 17022, configured to continuously search for a matching frequency in a j-th pulse period in the rf fm path and a first rf power stage of a plurality of pulse periods located behind the j-th pulse period according to the first initial frequency until an impedance parameter corresponding to the searched frequency reaches an extremum, and read a specific frequency in the process of searching for the matching frequency in the first rf power stage of each pulse period; the specific frequency modulation frequency of the first radio frequency power stage of the previous pulse period of two adjacent pulse periods is used as the initial frequency of the first radio frequency power stage of the next pulse period in the j-th pulse period and a plurality of pulse periods positioned behind the j-th pulse period in the radio frequency modulation path;

The determining unit 17023 is configured to determine a radio frequency corresponding to the extremum of the impedance parameter as a matching frequency of the plasma impedance for a first radio frequency power stage of the pulsed radio frequency power in the radio frequency modulation path.

The impedance matching device for pulsed radio frequency plasma provided by the embodiment of the application comprises: a dividing unit 1701 and an impedance matching unit 1702, and the impedance matching unit 1702 includes: an acquisition unit 17021, a search unit 17022, and a determination unit 17023. In the device, the matching frequency is searched continuously in the first radio frequency power stage of the ith pulse period and a plurality of pulse periods which are positioned at least one pulse period after the ith pulse period, the specific allocation frequency read by the previous pulse in the process of searching the matching frequency is assigned to the next pulse, and the next pulse is used as the initial frequency of the next pulse, so that the width of the first radio frequency power stage of one pulse period is increased, and the matching frequency of the pulse radio frequency plasma with higher pulse frequency can be searched through continuous frequency modulation of the first radio frequency power stage of the plurality of pulses, and the impedance matching of the plasma with higher pulse frequency is realized.

In both embodiments provided above, the matching frequency matched to the plasma impedance is obtained through a rf tuning interval. In addition, in order to further improve the accuracy of the matching frequency, the matching frequency matched with the plasma impedance can be obtained through a plurality of radio frequency modulation intervals in sequence.

Thus, embodiments of the present application provide yet another implementation of an impedance matching device for pulsed radio frequency plasma, as will be explained and illustrated below in conjunction with the accompanying drawings.

Referring to fig. 18, a schematic structural diagram of another implementation of an impedance matching device for pulsed rf plasma according to an embodiment of the present application is shown.

As an implementation manner, as shown in fig. 18, an impedance matching device for pulsed radio frequency plasma provided in the embodiment of the present application includes:

a dividing unit 1801, configured to divide a pulsed rf power including n pulse periods into K adjacent rf frequency modulation intervals, where each rf frequency modulation interval includes at least one pulse period; the pulse period includes a first radio frequency power phase; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer, K is not less than 2, and K is a positive integer;

An obtaining unit 1802, configured to obtain a first initial frequency of a kth rf fm interval, K < K, where K is a positive integer;

a searching unit 1803, configured to continuously search for a matching frequency in a kth rf frequency-modulating interval and each pulse period in a plurality of subsequent rf frequency-modulating intervals according to the first initial frequency until an impedance parameter corresponding to the searched rf frequency reaches an extremum, and read a specific rf frequency in the process of searching for the matching frequency in a first rf power stage of each pulse period of each rf frequency-modulating interval; wherein, in the kth radio frequency modulation interval and a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval, the specific frequency modulation frequency of the first radio frequency power stage of the previous radio frequency modulation interval of two adjacent radio frequency modulation intervals is used as the initial frequency of the first radio frequency power stage of the next radio frequency modulation interval;

a determining unit 1804 is configured to determine a radio frequency corresponding to the extremum of the impedance parameter as a matching frequency for matching the plasma impedance during the first radio frequency power phase of the pulsed radio frequency power.

The impedance matching device for pulsed radio frequency plasma provided by the embodiment of the application comprises: a dividing unit 1801, an acquiring unit 1802, a searching unit 1803, and a determining unit 1804. In the device, firstly, pulse radio frequency power comprising n pulse periods is divided into K adjacent radio frequency modulation intervals, secondly, a first initial frequency of the kth radio frequency modulation interval is obtained, then, a matching frequency is continuously searched in the kth radio frequency modulation interval and each pulse period in a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval according to the first initial frequency until impedance parameters corresponding to the searched frequency modulation frequency reach an extremum, and finally, the radio frequency corresponding to the impedance parameters reaching the extremum is determined as the matching frequency of a first radio frequency power stage of the pulse radio frequency power and plasma impedance.

Based on the impedance matching method of the pulsed radio frequency plasma and the impedance matching device of the pulsed radio frequency plasma provided by the embodiments, the embodiments of the application also provide a plasma processing device, which is explained and illustrated below with reference to the drawings.

Referring to fig. 19, a schematic diagram of a structure of a plasma processing apparatus according to an embodiment of the present application is shown.

The plasma processing apparatus provided in the embodiment of the application includes: a plasma processing chamber 1901 and a radio frequency power generator 1902;

the plasma processing chamber 1901 is used to receive and process a substrate;

the rf power generator 1902 is configured to output pulsed rf power to the plasma reaction chamber, the pulsed rf power comprising n pulse periods, each pulse period comprising a first rf power stage; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer;

the rf power generator 1902 includes an auto-frequency modulation device 19021, and the auto-frequency modulation device 19021 is configured to perform any one of the impedance matching methods of pulsed rf plasma provided in the foregoing embodiments.

As an embodiment, the plasma processing apparatus further includes:

the random command generator 1903 is configured to set a duration of a radio frequency modulation interval, and send a set duration signal of the radio frequency modulation interval to the radio frequency power generator 1902, so that the radio frequency power generator divides the radio frequency modulation interval according to the duration signal of the radio frequency modulation interval.

As another embodiment, an impedance matching network 1904 may be provided between the rf power generator 1902 and the plasma processing chamber 1901 in order to increase the efficiency of power feed into the plasma processing chamber 1901.

The plasma processing apparatus provided in the embodiment of the application includes: a plasma processing chamber 1901 and a radio frequency power generator 1902, and the radio frequency power generator 1902 includes an auto-frequency modulation device 19021. In the device, first initial frequency in a first radio frequency power stage of an ith pulse period is firstly obtained, then matching frequency is continuously searched in the first radio frequency power stage of the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period according to the first initial frequency until impedance parameters corresponding to the searched radio frequency reach an extremum, and finally the radio frequency corresponding to the impedance parameters when the impedance parameters reach the extremum is determined as the matching frequency of the first radio frequency power stage of the pulse radio frequency power and plasma impedance.

Claims

1. An impedance matching method of a pulsed radio frequency plasma, comprising:

searching matching frequency in the ith pulse period and the first radio frequency power stage of a plurality of pulse periods positioned behind the ith pulse period continuously according to the first initial frequency until the impedance parameter corresponding to the searched frequency modulation frequency reaches an extremum, and performing frequency modulation on the frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period for a plurality of times and reading the specific frequency modulation frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period; wherein, in the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period, the specific frequency modulation frequency of the first radio frequency power stage of the previous pulse period of the two adjacent pulse periods is used as the initial frequency of the first radio frequency power stage of the next pulse period;

Determining the corresponding radio frequency when the impedance parameter reaches the extremum as the matching frequency of the first radio frequency power stage of the pulse radio frequency power and the plasma impedance;

the specific frequency modulation frequency is the matching frequency which is matched with the plasma impedance and is found in the first radio frequency power stage of the pulse period, or the frequency modulation frequency which is randomly read in the process of searching the matching frequency in the first radio frequency power stage of the pulse period.

2. The method of claim 1, wherein the first initial frequency is a manually assigned frequency or a previously auto-tuned frequency.

3. A method according to claim 1 or 2, wherein the plurality of pulse periods following the ith pulse period are a plurality of consecutive pulse periods adjacent to the ith pulse period.

4. A method according to claim 1 or 2, wherein the plurality of pulse periods following the ith pulse period are a plurality of pulse periods spaced from the ith pulse period by at least one pulse period and spaced therebetween by at least one pulse period.

5. An impedance matching method of pulse radio frequency plasma is characterized in that pulse radio frequency power comprising n pulse periods is divided into a plurality of radio frequency modulation paths in advance, and each radio frequency modulation path comprises at least two non-adjacent pulse periods; each pulse period includes a first radio frequency power phase; the first radio frequency power stage is a high radio frequency power stage or a low radio frequency power stage; n is a positive integer;

Determining the corresponding radio frequency when the impedance parameter reaches the extremum as the matching frequency of the plasma impedance at the first radio frequency power stage of the pulse radio frequency power in the radio frequency modulation path;

6. The method of claim 5, wherein the first initial frequency is a manually assigned frequency or a previously auto-tuned frequency.

7. The method of claim 5 or 6, wherein the at least two non-adjacent pulse periods included in each of the radio frequency modulation paths are a plurality of equally spaced non-adjacent pulse periods.

8. An impedance matching method of a pulsed radio frequency plasma, comprising:

continuously searching matching frequencies in the kth radio frequency modulation interval and each pulse period in a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval according to the first initial frequency until impedance parameters corresponding to the searched matching frequencies reach an extremum, and performing frequency modulation for a plurality of times on the frequency of the searching matching frequencies in the first radio frequency power stage of each pulse period of each radio frequency modulation interval and reading specific frequency modulation frequencies in the searching matching frequencies in the first radio frequency power stage of each radio frequency modulation interval in the process of searching the matching frequencies in the first radio frequency power stage of each pulse period of each radio frequency modulation interval; wherein, in the kth radio frequency modulation interval and a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval, the specific frequency modulation frequency of the first radio frequency power stage of the previous radio frequency modulation interval of two adjacent radio frequency modulation intervals is used as the initial frequency of the first radio frequency power stage of the next radio frequency modulation interval;

The specific frequency modulation frequency is the matching frequency which is matched with the plasma impedance and is found in the first radio frequency power stage of each pulse period of the radio frequency modulation interval, or the frequency modulation frequency which is randomly read in the process of searching the matching frequency in the first radio frequency power stage of each pulse period of the radio frequency modulation interval.

9. The method of claim 8, wherein the first initial frequency is a manually assigned frequency or a previously auto-tuned frequency.

10. The method of claim 8, wherein the number of pulse periods per rf frequency modulation interval is set to any integer value.

11. An impedance matching device for pulsed radio frequency plasma, comprising:

The searching unit is used for continuously searching the matching frequency in the i-th pulse period and the first radio frequency power stage of a plurality of pulse periods positioned behind the i-th pulse period according to the first initial frequency until the impedance parameter corresponding to the searched frequency modulation frequency reaches the extremum, and performing frequency modulation on the frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period and reading the specific frequency modulation frequency in the process of searching the matching frequency in the first radio frequency power stage of each pulse period; wherein, in the ith pulse period and a plurality of pulse periods positioned behind the ith pulse period, the specific frequency modulation frequency of the first radio frequency power stage of the previous pulse period of the two adjacent pulse periods is used as the initial frequency of the first radio frequency power stage of the next pulse period;

the determining unit is used for determining the corresponding radio frequency when the impedance parameter reaches the extreme value as the matching frequency of the first radio frequency power stage of the pulse radio frequency power and the plasma impedance;

12. An impedance matching device for pulsed radio frequency plasma, comprising:

the impedance matching unit specifically includes:

The determining unit is used for determining the corresponding radio frequency when the impedance parameter reaches the extreme value as the matching frequency of the first radio frequency power stage of the pulse radio frequency power in the radio frequency modulation path and the plasma impedance;

13. An impedance matching device for pulsed radio frequency plasma, comprising:

The searching unit is used for continuously searching the matching frequency in the kth radio frequency modulation interval and each pulse period in a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval according to the first initial frequency until the impedance parameter corresponding to the searched matching frequency reaches the extremum, and performing frequency modulation on the frequency of the searching matching frequency in the first radio frequency power stage of each pulse period of each radio frequency modulation interval for multiple times and reading the specific frequency modulation frequency in the process of searching the matching frequency in the first radio frequency power stage of each radio frequency modulation interval; wherein, in the kth radio frequency modulation interval and a plurality of radio frequency modulation intervals positioned behind the kth radio frequency modulation interval, the specific frequency modulation frequency of the first radio frequency power stage of the previous radio frequency modulation interval of two adjacent radio frequency modulation intervals is used as the initial frequency of the first radio frequency power stage of the next radio frequency modulation interval;

14. A plasma processing apparatus, comprising:

a plasma processing chamber and a radio frequency power generator;

wherein the rf power generator comprises an auto-tuning device for performing the impedance matching method of the pulsed rf plasma of any one of claims 1 to 10.

15. The plasma processing apparatus according to claim 14, characterized in that the plasma processing apparatus further comprises: