CN112509899B - Inductively coupled plasma processing apparatus and ignition control method thereof - Google Patents
Inductively coupled plasma processing apparatus and ignition control method thereof Download PDFInfo
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- 238000009616 inductively coupled plasma Methods 0.000 title claims abstract description 30
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- 238000010168 coupling process Methods 0.000 claims abstract description 34
- 239000000758 substrate Substances 0.000 claims abstract description 19
- 230000001939 inductive effect Effects 0.000 claims abstract description 18
- 230000008093 supporting effect Effects 0.000 claims abstract description 7
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- 230000001133 acceleration Effects 0.000 abstract description 8
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32082—Radio frequency generated discharge
- H01J37/321—Radio frequency generated discharge the radio frequency energy being inductively coupled to the plasma
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32366—Localised processing
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/3065—Plasma etching; Reactive-ion etching
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/32—Processing objects by plasma generation
- H01J2237/33—Processing objects by plasma generation characterised by the type of processing
- H01J2237/334—Etching
- H01J2237/3341—Reactive etching
Abstract
The invention discloses an ignition control method of an inductively coupled plasma processing device, which is provided with a vacuum processing cavity, a radio frequency power source and a bias power source, wherein the radio frequency power source couples radio frequency signals into the vacuum processing cavity through an inductive coupling coil, and the bias power source applies bias signals to a base in the vacuum processing cavity through a radio frequency matching network, and the base is used for supporting a substrate to be processed; the method comprises the following steps: acquiring a control instruction; the bias power source executes the control instruction and generates the bias signal; the bias signal is pulse voltage and is used for igniting plasma together with the radio frequency signal. By controlling the opening time of the radio frequency power source and the bias power source and adjusting the duty ratio and the voltage of the pulse voltage of the bias power source, the method provided by the invention can realize high-efficiency ignition and uniform acceleration of plasma.
Description
Technical Field
The invention relates to the technical field of plasma treatment, in particular to an inductively coupled plasma treatment device and an ignition control method thereof.
Background
In a plasma processing apparatus, a radio frequency power supply supplies power to a process chamber to generate a plasma. The plasma contains a large amount of active particles such as electrons, ions, excited atoms, molecules, free radicals and the like, and the active particles interact with a wafer to be processed or a workpiece to be processed which is placed in a cavity and exposed in a plasma environment, so that the surface of the wafer or the workpiece is subjected to plasma reaction, and the surface performance of the wafer or the workpiece is changed, thereby completing plasma etching or other technological processes.
In the above-described plasma processing apparatus, an inductively coupled plasma (Inductively Coupled Plasma, abbreviated as ICP) processing apparatus uses an induction coil to couple radio frequency power into a processing chamber of the processing apparatus by providing the induction coil outside the processing apparatus. In ICP technology, there is both capacitive coupling, which is discharge caused by an electric field generated by electric charges, and inductive coupling, which is discharge caused by a magnetic field generated by an induction coil. The capacitive coupling of the high pressure generated in the process chamber during the plasma ignition formation greatly assists the ignition plasma in the initiation of the inductive discharge. However, when the substrate processing process is performed after the plasma is ignited, the acceleration of the plasma by the electric field on the induction coil is not uniform due to the accompanying capacitive discharge of the induction coil, which results in non-uniform processing results of the plasma on the substrate.
In order to avoid the non-uniform effect of the capacitive coupling phenomenon in the plasma treatment process, technicians perform a series of modifications to the shape of the induction coil, so that the voltage on each induction coil branch can be effectively reduced, and the capacitive coupling caused by high voltage on the induction coil can be effectively inhibited, so as to ensure uniform treatment of the substrate by the plasma. However, the reduction in the capacitive coupling makes it difficult for the plasma to ignite under conditions that produce a low-pressure low-density plasma.
Disclosure of Invention
In view of this, embodiments of the present invention provide an inductively coupled plasma processing apparatus and an ignition control method thereof, so as to achieve efficient ignition and uniform acceleration of plasma.
In order to achieve the above object, the embodiment of the present invention provides the following technical solutions:
an ignition control method of an inductively coupled plasma processing apparatus having a vacuum processing chamber, a radio frequency power source coupling a radio frequency signal into the vacuum processing chamber through an inductive coupling coil, and a bias power source applying a bias signal to a susceptor inside the vacuum processing chamber through a radio frequency matching network, the susceptor being for supporting a substrate to be processed;
the method comprises the following steps:
acquiring a control instruction;
the bias power source executes the control instruction and generates the bias signal;
the bias signal is pulse voltage and is used for igniting plasma together with the radio frequency signal.
Preferably, the bias power source executes the control instruction to generate the bias signal, including:
executing the control instruction, and starting the bias power source so that the bias power source generates the bias signal;
and after the bias power source is started for a set time, starting the radio frequency power source so that the radio frequency power source generates the radio frequency signal.
Preferably, in the above method, the set time is less than 200ms.
Preferably, in the above method, the duty ratio of the pulse voltage is set to be lower than 10%.
Preferably, in the above method, the bias power of the pulse voltage is set to be less than 50 watts.
Preferably, in the above method, the forming process of the plasma includes:
and setting the time from the start of the radio frequency power source to the generation of plasma in the vacuum processing cavity as T, and setting the pulse width of the pulse voltage as 0.1T-10T.
Preferably, in the above method, the forming process of the plasma includes:
the time from the start of the radio frequency power source to the generation of plasma in the vacuum processing cavity is T, the start time of the bias power source is not later than the time of the radio frequency power source, and the start duration is not less than T.
Preferably, in the above method, the inductance coupling coil is a structure of a plurality of single-turn coil combinations or a plurality of half-turn coil combinations.
The invention also provides an inductively coupled plasma processing apparatus, comprising:
a vacuum processing chamber, a radio frequency power source, and a bias power source;
the radio frequency power source couples radio frequency signals into the vacuum processing cavity through the inductance coupling coil, and the bias power source applies bias signals to a base in the vacuum processing cavity through the radio frequency matching network, and the base is used for supporting a substrate to be processed;
the bias power source is used for executing a control instruction and generating the bias signal; the bias signal is pulse voltage and is used for igniting plasma together with the radio frequency signal.
Preferably, in the above device, the inductance coupling coil has a structure in which a plurality of single-turn coils are combined or a plurality of half-turn coils are combined.
As can be seen from the above description, in the inductively coupled plasma processing apparatus and the ignition control method thereof provided by the technical scheme of the present invention, the pulse voltage output by the bias power source can be used as a bias signal to perform plasma ignition together with the rf signal. In the prior art, in order to achieve the purpose of uniform acceleration, the coil structure needs to be changed, so that the purpose of uniform acceleration is achieved by weakening or even eliminating capacitive coupling, but ignition is not easy to happen. By controlling the opening time of the radio frequency power source and the bias power source and adjusting the duty ratio and the voltage of the pulse voltage of the bias power source, the method provided by the invention can realize high-efficiency ignition and uniform acceleration of plasma.
Drawings
In order to more clearly illustrate the embodiments of the present invention 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 embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an inductively coupled plasma processing apparatus according to the present invention;
FIG. 2 is a flow chart of a method for controlling ignition of an inductively coupled plasma processing apparatus according to the present invention;
FIG. 3 is a diagram of a source RF reflected power model for ignition of inductively coupled plasma in accordance with the present invention;
FIG. 4 is a graph of a pulse voltage model at the beginning of ignition of an inductively coupled plasma in accordance with the present invention;
fig. 5 is a circuit diagram of a radio frequency matching network connected to a bias power source according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
As shown in fig. 1, fig. 1 is a schematic structural diagram of an inductively coupled plasma processing apparatus according to the present invention, in the schematic structural diagram shown in fig. 1, the inductively coupled plasma processing apparatus includes a vacuum processing chamber 100, the vacuum processing chamber 100 includes a cylindrical or approximately cylindrical processing chamber sidewall 105 made of a metal material, an insulating window 130 is disposed above the processing chamber sidewall 105, an inductive coupling coil 140 is disposed above the insulating window 130, and the inductive coupling coil 140 is connected to a radio frequency power source 145. The chamber sidewall 105 has a gas inlet 150 disposed at an end thereof adjacent to the insulating window 130, the gas inlet 150 being connected to the gas supply apparatus 10. A susceptor 110 is provided at a downstream position inside the vacuum processing chamber 100, and an electrostatic chuck 11 is placed on the susceptor 110 for supporting and fixing the substrate 120. An exhaust pump 125 is also provided below the vacuum processing chamber 100 for exhausting the reaction byproducts out of the vacuum processing chamber 100. An rf matching network 200 is provided between the rf bias power source 146 and the susceptor 110 for maximizing the application of the rf power source output power into the vacuum processing chamber 100. In addition, a voltage measuring device 116 is disposed on the surface of the electrostatic chuck 115 for measuring the voltage on the surface of the substrate 120.
Before the process starts, the substrate 120 is transferred to the electrostatic chuck 115 above the susceptor 110 to be fixed, and the reaction gas in the gas supply apparatus 10 is introduced into the vacuum processing chamber 100 through the gas injection port 150, and then the rf power source 145 is applied to the inductive coupling coil 140. In the conventional art, the inductive coupling coil 140 has a multi-turn single coil structure, and this coil structure can generate a larger rf voltage in the vacuum processing chamber 100 to help the inductive discharge generated by the rf power source 145 on the coil ignite the reaction gas in the vacuum processing chamber 100, and the rf power of the rf power source 145 drives the inductive coupling coil 140 to generate a stronger high-frequency alternating magnetic field, so that the low-pressure reaction gas is ionized to generate the plasma 160. The plasma 160 contains a large number of active particles such as electrons, ions, atoms in an excited state, molecules, free radicals, and the like, and the active particles can react with the surface of the substrate 120 to be processed in various physical and chemical ways, so that the shape of the surface of the substrate 120 is changed, namely, the etching process is completed.
However, as described in the background art, the capacitive coupling reaction generated by the plurality of single inductive coupling coils 140 has an adverse effect on the uniformity of the processing of the substrate 120, that is, the uneven capacitive discharge carried by the inductive coupling coils 140 causes uneven acceleration of the plasma 160 by the electric field on the inductive coupling coils 140, and thus uneven processing results of the substrate 120 by the plasma 160. The structure of the inductance coupling coil 140 may be changed to reduce or eliminate capacitive discharge generated by the inductance coupling coil 140, so as to ensure uniformity of processing of the substrate 120, for example, the inductance coupling coil 140 adopted in the present invention is a structure of a plurality of single-coil combinations or a plurality of half-coil combinations. However, the structure of the combination of the plurality of single coils or the combination of the plurality of half coils adopted in the present invention can promote the uniform acceleration of the plasma 160 and ensure the uniformity of the processing of the substrate 120, but has difficulty in igniting the reaction gas in the vacuum processing chamber 100 under the condition of low pressure and low density due to the reduced capacitive discharge generated by the inductive coupling coil 140.
It should be noted that, in order to reduce or eliminate the capacitive discharge generated by the inductance coupling coil 140, the inductance coupling coil 140 includes, but is not limited to, a structure formed by combining a plurality of single coils or a plurality of half coils.
In order to solve the problem that plasma is difficult to ignite in the inductively coupled plasma processing apparatus of the present invention, the present invention provides a method of applying a control command to a bias power source to assist in igniting the plasma. In a plasma etching process, a rf power source 145 is applied to the inductively coupled coil 140 to control plasma dissociation or plasma density, and a rf bias power source 146 applies a generated bias signal pulse pattern to the susceptor 110 by applying a control command, the bias power source 146 serving to control ion energy and its energy distribution. The reactant gases within the vacuum processing chamber 100 are dissociated into a plasma prior to performing a plasma etching step on the substrate 120. The bias power source 146 is operative to generate a bias signal in the vacuum processing chamber 100 during ignition of the plasma and to assist the rf signal of the rf power source 145 with the pulsed voltage of the bias signal pulse pattern to achieve ignition of the plasma.
As shown in fig. 2, fig. 2 is a flowchart of a method for controlling ignition of an inductively coupled plasma processing apparatus according to the present invention, which is used in the apparatus shown in fig. 1, and specifically, the method includes:
s201: and acquiring a control instruction.
In the method provided by the embodiment of the invention, when the plasma is difficult to ignite under the condition of low pressure and low density of the reaction gas in the vacuum processing cavity, the bias power source is triggered to acquire the control instruction.
In one form, the apparatus further comprises a controller electrically connected to the bias power source, the controller being operable to generate the control command in response to a signal generated by a sensor in the inductively coupled plasma processing apparatus. In another mode, the control command may be directly input to the bias power source manually.
S202: the bias power source executes the control instruction and generates the bias signal; the bias signal is pulse voltage and is used for igniting plasma together with the radio frequency signal.
In the method provided by the embodiment of the invention, after the bias power source acquires the control instruction, the bias power source executes the control instruction and starts the bias power source so as to enable the bias power source to generate the bias signal, and the bias signal is set to be pulse voltage in a pulse mode and is used for carrying out plasma ignition together with the radio frequency signal. Wherein the radio frequency signal is generated by the radio frequency power source. In the embodiment of the present invention, the pulse voltage is used as the bias signal to perform auxiliary ignition, and it should be noted that in other manners, the bias signal may also be in a continuous wave mode.
In the method provided by the embodiment of the invention, a control instruction is applied to the bias power source of the inductively coupled plasma processing device, the control instruction is executed by the bias power source to generate a bias signal, the bias signal is set to be pulse voltage in a pulse mode, and in a subsequent processing process, the pulse voltage and the radio frequency signal are used for assisting the ignition of plasma together. By applying the method provided by the invention, the ignition performance of the plasma is improved, and the ignition of the plasma is ensured.
As shown in fig. 3, fig. 3 is a diagram of a source rf reflected power model when an inductively coupled plasma is ignited, which specifically includes:
in the figure, the horizontal axis represents time t (ms), and the vertical axis represents power P (w). P in the figure Fwd For incident power, i.e. the output power of the RF power source, to remain constant throughout the ignition process, P Ref The reflected power is the reflected power detected by the radio frequency power source after being reflected, i.e. the radio frequency power source is not completely absorbed after being output. Stage A represents the process of plasma formation and stabilization, which reflects power P Ref Is about equal to the incident power P Fwd That is, when no plasma is generated, the RF power source outputs power corresponding to the total reflection, so that the reflected power P Ref Is about equal to the incident power P Fwd The method comprises the steps that ignition is completed at the junction moment of a phase A and a phase B, plasma is generated, the plasma absorbs energy to reduce reflected power, reflected power jump from the phase A to the phase B is inherent, and a matching network between a radio frequency power source and a coupling coil is regulated in a phase C to further reduce the reflected power; stage B represents a stage before adjusting impedance matching after plasma ignition, and stage C represents a stage of adjusting radio frequency signals through the matching network to perform impedance matching so as to improve the power utilization rate of the radio frequency power source.
During plasma ignition, a high electric field is critical to accelerating the initial electrons of the plasma discharge, and the higher the voltage applied to the reaction chamber, the more helpful the plasma ignition. If the plasma fails to ignite, the period of phase A will be extended, so the plasma cannot transition to phase B. The pulse voltage frequency of the bias signal and the phase a are one order of magnitude, in theory, the ignition contribution, the phase B and the phase C do not need to apply the bias signal, but the existing hardware control precision makes the bias signal action time not accurate enough to only act on the phase a, so that the bias power source can be enabled to cover at least the phase a, and make the bias signal act on at least the whole phase a to complete the ignition. If the a duration is T, the pulse width of the pulse voltage is 0.1T to 10T, and the specific time of the pulse width of the pulse voltage may be set based on the requirement, not limited to this range. As shown in fig. 3, t=xms, e.g., x can be 0.2ms, 1ms, or 2ms. In addition, in the illustration, the duration of the phase a to the phase B is 10ms, and the duration of the phase a to the phase B to the phase C is less than 1000ms.
In practical work, the ignition stage a is shorter, usually only a few milliseconds, and is limited by hardware technology, and the radio frequency power supply needs a few seconds to switch different output voltages, so if the output voltage of the bias radio frequency power supply is higher in the ignition stage, the higher bias radio frequency voltage can continue to stage B and stage C due to the short ignition stage time, and adverse effects are generated on the process of stage B and stage C. In order to improve the ignition performance of the plasma, in the process of forming the plasma in the stage A, on one hand, the duty ratio of the pulse voltage is set to be lower than 10%, the power value is smaller than 50 watts, and the pulse voltage is transmitted to the vacuum processing cavity in a pulse mode, so that the ignition effect can be improved by using the output voltage of a higher bias radio frequency power supply through the smaller duty ratio, the whole power in the ignition stage cannot be increased, and meanwhile, the influence of high output power on the processes in the stage B and the stage C is effectively avoided. In addition, in the absence of a plasma, a relatively small pulsed voltage may generate a high voltage in the chamber to accelerate the initial electrons. On the other hand, after the bias power source is started in advance and the time is set, the radio frequency power source is started. Wherein the set time is less than 200ms, for example, may be less than 20ms, and the time may be set based on the requirement, not limited to this range. When the time from the start of the radio frequency power source to the generation of plasma in the vacuum processing cavity is T, the start time of the bias power source is not later than the time of the radio frequency power source, and the start duration is not less than T. The bias power source may be set to be turned on in advance based on the requirement, for example, T may be 15ms or 10ms, or may be turned on synchronously with or later than the rf power source in other manners. As known, the purpose of quick ignition can be realized by early opening, so the application preferably sets the bias power source to early open.
The duty ratio of the pulse voltage is not limited to less than 10%, and the duty ratio may be set based on the requirement, and may be not limited to this range, but may be higher than 10%; the bias power of the pulse voltage is not limited to be less than 50 watts, and the bias power can be set based on requirements, is not limited to the range and can be greater than 50 watts; the turn-on time of the bias power source is not limited to be earlier than the turn-on time of the radio frequency power source, and may be later than the turn-on time of the radio frequency power source or the bias power source and the radio frequency power source are turned on synchronously. The working parameters of the bias power source may be preset through the control command, and the working parameters of the pulse voltage, such as period, duty cycle, power, etc. may be set based on actual requirements, including but not limited to the above-mentioned example values in the embodiments of the present application.
As shown in fig. 4, fig. 4 is a pulse voltage model diagram at the beginning of ignition of an inductively coupled plasma according to the present invention. As shown in the figure, the method specifically comprises the following steps:
in the figure, the horizontal axis represents time t (ms), and the vertical axis represents power P (w). P in the figure Fwd For incident power, i.e. the output power of the RF power source, to remain constant throughout the ignition process, P Ref The reflected power, i.e. the part of the rf power source that is not fully absorbed after output, is detected by the reflected rf power source. Stage A represents the process of plasma formation and stabilization, which reflects power P Ref Is about equal to the incident power P Fwd The ignition is completed at the interface time of the phase A and the phase B, plasma is generated, the plasma absorbs energy, the reflected power is reduced, the reflected power jump from the phase A to the phase B is inherent, and the phase B is expressed as the phase before the impedance matching is regulated after the plasma ignition. As shown in fig. 4, t=xms, e.g., x can be 0.2ms, 1ms, or 2ms. In the illustration, the duration of phase a to phase B is 10ms. In addition, the second graph in FIG. 4 shows the incident power P Fwd Over time TA pulse model generated by the change.
Based on the above embodiment of the ignition control method, another embodiment of the present invention further provides an inductively coupled plasma processing apparatus for implementing the above ignition control method, where the inductively coupled plasma processing apparatus is shown in fig. 1, and includes:
a vacuum processing chamber 100, a radio frequency power source 145, and a bias power source 146; the rf power source 145 couples rf signals into the vacuum processing chamber 100 through the inductive coupling coil 140, the bias power source 146 applies bias signals to the susceptor 110 inside the vacuum processing chamber 100 through the rf matching network 200, and the susceptor 110 is used for supporting the substrate 120 to be processed; wherein the bias power source 146 is configured to execute a control instruction to generate the bias signal; the bias signal is pulse voltage and is used for igniting plasma together with the radio frequency signal.
The inductance coupling coil 140 is a structure of a combination of a plurality of single coils or a combination of a plurality of half coils.
By using the inductively coupled plasma processing device provided by the embodiment of the invention, the ignition performance of the plasma can be improved and the ignition of the plasma can be ensured by controlling the opening time of the radio frequency power source and the bias power source and adjusting the duty ratio and the voltage of the pulse voltage.
It should be noted that, in fig. 1, a radio frequency matching network 200 is disposed between the radio frequency bias power source 146 and the base 110, the structure of the matching network is shown in fig. 5, fig. 5 is a circuit diagram of the radio frequency matching network connected to the bias power source, and an output end of the bias power source 146 is connected to a load impedance through the radio frequency matching network 200, where the load impedance is an impedance in the vacuum processing chamber 100. When plasma is present in the vacuum processing chamber 100, the load impedance is the sum of the impedance of the vacuum processing chamber 100, the electrostatic chuck 115, and the plasma; when no plasma is present within the vacuum processing chamber 100, the load impedance is the sum of the impedances of the vacuum processing chamber 100 and the electrostatic chuck 115.
As shown in fig. 5, the radio frequency matching network 200 includes: variable capacitance 201 and variable capacitance 202. The output of the bias power source 146 is grounded through a variable capacitor 201 and connected to the load impedance through a variable capacitor 202. By adjusting the variable capacitance 201 and/or the variable capacitance 202, the magnitude of the pulsed voltage output by the bias power source 146 can be adjusted to control the magnitude of the voltage applied to the susceptor surface to assist in plasma ignition.
Optionally, the radio frequency matching network 200 further includes a resistor Rs and an inductor L. The output of the bias power source 146 is connected to the variable capacitor 201 through the resistor Rs to be grounded through the variable capacitor 201, and the output of the bias power source 146 is connected to the load impedance through the resistor Rs, the inductor L, and the variable capacitor 202 in sequence.
Based on the embodiment of the rf matching network 200, another matching network is provided between the rf power source 145 and the inductive coupling coil 140, after the plasma ignition is completed, in the above control method, the matching network may be adjusted to improve the power utilization rate of the rf power source, which is not shown in the figure, and the implementation manner of the matching network may refer to the rf matching network 200 and will not be described again.
As can be seen from the above description, in the method provided by the embodiment of the present invention, a control command is applied to a bias power source of an inductively coupled plasma processing apparatus, the control command is executed by the bias power source to generate a bias signal, the bias signal is set to a pulse voltage in a pulse mode, and in a subsequent processing process, the ignition of plasma is assisted by the pulse voltage and a radio frequency signal together. By applying the method provided by the invention, the ignition performance of the plasma is improved, and the ignition of the plasma is ensured.
In this specification, each embodiment is described in a progressive manner, or in parallel, or in a combination of parallel and progressive manners, and each embodiment is mainly described as different from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
It is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in an article or apparatus that comprises such element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. An ignition control method of an inductively coupled plasma processing apparatus, wherein the apparatus has a vacuum processing chamber, a radio frequency power source and a bias power source, the radio frequency power source couples a radio frequency signal into the vacuum processing chamber through an inductive coupling coil, the bias power source applies a bias signal to a pedestal inside the vacuum processing chamber through a radio frequency matching network, the pedestal is used for supporting a substrate to be processed;
the method comprises the following steps:
acquiring a control instruction;
the bias power source executes the control instruction and generates the bias signal;
the bias signal is pulse voltage and is used for igniting plasma together with the radio frequency signal; the duty cycle of the pulse voltage is lower than 10%;
the time from the start of the radio frequency power source to the first generation of plasma in the vacuum processing cavity is T, the start time of the bias power source is not later than the start time of the radio frequency power source, and the start duration is not less than T; the pulse width of the pulse voltage is 0.1T-10T; the bias power of the pulse voltage is set to be less than 50 watts.
2. The method of claim 1, wherein the bias power source executing the control instruction to generate the bias signal comprises:
executing the control instruction, and starting the bias power source so that the bias power source generates the bias signal;
and after the bias power source is started for a set time, starting the radio frequency power source so that the radio frequency power source generates the radio frequency signal.
3. The method of claim 2, wherein the set time is less than 200ms.
4. The method of claim 1, wherein the bias power of the pulsed voltage is set to less than 50 watts.
5. The method of claim 1, wherein the forming of the plasma comprises:
setting the time from the start of the radio frequency power source to the initial generation of plasma in the vacuum processing cavity as T, and setting the pulse width of the pulse voltage as 0.1T-10T.
6. The method of claim 1, wherein the forming of the plasma comprises:
the time from the start of the radio frequency power source to the first generation of plasma in the vacuum processing cavity is T, the start time of the bias power source is not later than the start time of the radio frequency power source, and the start duration is not less than T.
7. The method of any of claims 1-6, wherein the inductively coupled coil is a structure of a plurality of single turn coil combinations or a plurality of half turn coil combinations.
8. An inductively coupled plasma processing apparatus, comprising:
the device comprises a vacuum processing cavity, a radio frequency power source, a bias power source, a base and a controller;
the radio frequency power source couples radio frequency signals into the vacuum processing cavity through the inductance coupling coil, and the bias power source applies bias signals to a base in the vacuum processing cavity through the radio frequency matching network, and the base is used for supporting a substrate to be processed; the bias power source is electrically connected with the controller;
wherein the controller is used for generating a control instruction; the bias power source is used for executing the control instruction and generating the bias signal; the bias signal is pulse voltage and is used for igniting plasma together with the radio frequency signal; the duty cycle of the pulse voltage is lower than 10%;
the time from the start of the radio frequency power source to the first generation of plasma in the vacuum processing cavity is T, the start time of the bias power source is not later than the start time of the radio frequency power source, and the start duration is not less than T; the pulse width of the pulse voltage is 0.1T-10T; the bias power of the pulse voltage is set to be less than 50 watts.
9. The apparatus of claim 8, wherein the inductive coupling coil is a structure of a plurality of single-turn coil combinations or a plurality of half-turn coil combinations.
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