Patent Description:
Plasma processing systems for etching and deposition have been utilized for decades, but advancements in processing techniques and equipment technologies continue to create increasingly more complex systems. At the same time, the decreasing dimensions of structures created with workpieces requires increasingly precise control and interoperation of plasma processing equipment. Current control methodologies and associated systems are not capable of addressing several issues that are associated with the complex systems of today and tomorrow; thus, there is a need for new and improved control over disparate, yet interdependent, plasma processing equipment. <CIT> relates to a method is provided for processing a workpiece in a plasma reactor chamber. <CIT> relates to a method for controlling a potential of a susceptor of a plasma processing apparatus. <CIT> relates to a method for impedance matching of a plasma processing apparatus.

According to an aspect, a plasma processing system includes at least one modulating supply that modulates plasma properties where the modulation of the plasma properties has a repetition period, T. The plasma processing system includes a synchronization module configured to send a synchronization signal with a synchronization-signal-repetition-period, which is an integer multiple of T, to at least one piece of equipment connected to the plasma processing system. The plasma processing system also includes a waveform communication module configured to communicate characteristics of a characterized waveform with the repetition period T to least one piece of equipment connected to the plasma system to enable synchronization of pieces of equipment connected to the plasma processing system where the characterized waveform with the repetition period T contains at least one of information about the modulation of the plasma or information about a desired waveform of a piece of equipment connected to the plasma processing system.

Another aspect may be characterized as a control method for a plasma processing system. The method includes modulating plasma properties with a modulating supply where the modulation of the plasma properties has a repetition period, T. The method also includes characterizing a waveform with a repetition period, T, containing at least one of information about the modulation of the plasma or a desired waveform of a piece of equipment connected to the plasma processing system to produce a waveform dataset. The waveform dataset is sent to at least one piece of equipment connected to the plasma system, and the synchronization signal with a synchronization-signal-repetition-period that is an integer multiple of T to the at least one piece of equipment connected to the plasma system.

Yet another aspect may be characterized as a plasma processing control system that includes a waveform-characterization module configured to generate a waveform dataset for an output waveform of a piece of equipment connected to a plasma system. A waveform-repetition module is included to determine a repetition period, T, for a piece of equipment connected to the plasma system, and a waveform-communication module is configured to communicate the waveform data set to at least one of the piece of equipment or another piece of equipment connected to the plasma system. The plasma processing system also includes a waveform communication module and a synchronization module. The waveform communication module is configured to communicate the waveform dataset to at least one of the piece of equipment or another piece of equipment connected to the plasma system, and the synchronization module is configured to send a synchronization pulse with a synchronization pulse repetition period that is an integer multiple of T to a piece of equipment connected to the plasma system.

Preliminary note: the flowcharts and block diagrams in the following Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, some blocks in these flowcharts or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s).

While the following disclosure generally refers to wafer plasma processing, implementations can include any substrate processing within a plasma chamber. In some instances, objects other than a substrate can be processed using the systems, methods, and apparatus herein disclosed. In other words, this disclosure applies to plasma processing of any object within a sub-atmospheric plasma processing chamber to effect a surface change, subsurface change, deposition or removal by physical or chemical means.

This disclosure may utilize plasma processing and substrate biasing techniques as disclosed in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>. But it should be recognized that the reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter is conventional, routine, or forms part of the common general knowledge in the field of endeavor to which this specification relates.

For the purposes of this disclosure, source generators are those whose energy is primarily directed to generating and sustaining the plasma, while "bias supplies" are those whose energy is primarily directed to generating a surface potential for attracting ions and electrons from the plasma.

<FIG> shows an embodiment of a plasma processing system with many pieces of equipment coupled directly and indirectly to plasma chamber <NUM>, which contains a plasma <NUM>. The equipment includes vacuum handling and gas delivery equipment <NUM>, bias generators <NUM>, a bias matching network <NUM>, bias measurement and diagnostics <NUM>, source generators <NUM>, a source matching network <NUM>, source measurement and diagnostics <NUM>, measurement and diagnostics <NUM>, and a system controller <NUM>. The embodiment in <FIG>, and other embodiments described herein, are exemplary of the complexity of plasma processing systems, and the depiction of plasma systems herein helps to convey the interrelations of the equipment coupled to the plasma chamber <NUM>.

An example of the interrelations of the plasma processing equipment is the effect that modulating supplies (e.g., source generators <NUM>, bias generators <NUM>, and other modulating supplies discussed further herein) have on plasma properties (and control of the same). More specifically, modulating supplies can cause strong modulation of plasma properties such as the impedance presented by the plasma <NUM> to equipment of the plasma processing system <NUM>. Plasma modulation can also cause aliasing of measurements of plasma properties. Additional details about the effects of modulation of plasma properties are discussed further herein.

Shown in <FIG> is a plasma processing system <NUM> (e.g., deposition or etch system) containing a plasma chamber <NUM> within which a workpiece (e.g., a wafer) <NUM> is contained. A number of bias electrodes <NUM> are connected through the bias measurement and diagnostic system <NUM> to the bias match network <NUM> to which a number of bias generators <NUM> are connected. The bias electrodes <NUM> may be built into an electrostatic chuck to hold the workpiece <NUM> in place. This may involve integration of a high voltage DC power supply <NUM> into the system. In many applications, a single bias electrode <NUM> is used, but utilization of many bias electrodes <NUM> may be used to achieve a desired spatial control.

The bias generators <NUM> depicted in <FIG> may be lower frequency (e.g., <NUM> to <NUM>) RF generators that apply a sinusoidal waveform. Also shown is a set of source electrodes <NUM> connected to a number of source generators <NUM> through the source measurement and diagnostics system <NUM> and source matching network <NUM>. In many applications, power from a single source generator <NUM> is connected to one or multiple source electrodes <NUM>. The source generators <NUM> may be higher frequency RF generators (e.g. <NUM> to <NUM>). Vacuum maintenance, gas delivery and wafer handling equipment <NUM> may be implemented to complete the system and optionally additional measurement and diagnostic equipment <NUM> may be present (e.g. optical spectroscopy equipment).

The system controller <NUM> in the embodiment of <FIG> controls the entire system through a system control bus <NUM>. The system control bus <NUM> can also be used to collect information from equipment of the plasma processing system. In addition to the system control bus <NUM>, there may be dedicated inter-system communication <NUM> which can be used, for example, to control the source matching network <NUM> from a source generator <NUM> or exchange information between subsystems without involving the system control bus <NUM>. There may also be a near-real-time communication link <NUM> between subsystems. This may take the form of a reference oscillator to phase lock different generators on the system, to provide waveform synchronization signals, arc detection signals, etc. Although a single source generator <NUM> is common, it is also common to have multiple source generators <NUM> and multiple bias generators <NUM> in order to achieve a desired plasma density and desired control over the distribution of ion energies. One or more of the source generators <NUM> and/or bias generators <NUM> can modulate the plasma properties and be considered as a modulating supply.

<FIG> shows an embodiment of a plasma processing system <NUM> where the source generators <NUM> are replaced by a remote plasma source <NUM>. As those of ordinary skill in the art will appreciate, the remote plasma source <NUM> may include an excitation source (e.g., an RF generator) and a plasma-generation chamber configured and disposed to produce a plasma that is provided to the plasma chamber <NUM>. Although the remote plasma source <NUM> is outside of the plasma chamber <NUM>, the remote plasma source <NUM> may be coupled to the plasma chamber <NUM> to form a contiguous volume with the plasma chamber <NUM>. Although unlikely in many embodiments, in some embodiments, the remote plasma source <NUM> may modulate plasma properties of the plasma <NUM> in the plasma chamber <NUM>. And if the remote plasma source <NUM> does modulate the plasma properties of the plasma <NUM>, the remote plasma source <NUM> and/or one or more of the bias generators <NUM> can be considered as a modulating supply.

<FIG> shows another embodiment of a plasma processing system where multiple bias generators are replaced by an integrated bias power delivery system <NUM>. Such integration can reduce system complexity and reduce duplication by, for example, using common DC power supplies for the RF generators, a common controller, auxiliary power supplies, measurement systems etc., but the output to the plasma chamber <NUM> is still a combination of a single or multiple RF frequencies and/or a DC signal. Many other variations exist such as, for example, using a source generator and integrated bias power delivery system or using integrated source and bias power delivery systems etc..

Referring next to <FIG>, shown is yet another embodiment of a plasma processing system that utilizes a bias supply <NUM> (instead of bias generators <NUM>) for an even tighter control over the distribution of ion energies. As shown, the bias supply <NUM> may apply a periodic waveform to several different electrodes <NUM>, or alternatively, a separate bias supply <NUM> may be coupled to each electrode <NUM> (not shown in <FIG>). As shown in <FIG>, it is contemplated that multiple bias supplies <NUM> may be utilized in connection with multiple generators <NUM>. It should be recognized that the embodiments described with reference to <FIG> are not mutually exclusive and that various combinations of the depicted equipment may be employed.

Referring next to <FIG>, shown is a general representation of an exemplary bias supply <NUM> that may be used to realize the bias supplies <NUM>, <NUM>. As shown, the bias supply <NUM> utilizes three voltages V1, V2, and V3. Because the output, Vout, is capacitively coupled through Cchuck, it is generally not necessary to control the DC level of Vout and the three voltages can be reduced to two by choosing one of V1, V2 or V3 to be ground (0V). A separate chucking supply <NUM> may be used so it is not necessary to control the DC level of Vout. If a separate chucking supply is not used, all three voltages can be controlled to control the DC level of Vout. Although not shown for clarity, the two switches S1, and S2 may be controlled by a switch controller via electrical or optical connection to enable the switch controller to open and close the switches, S1, S2, as disclosed below. The depicted switches S1, S2 may be realized by single pole, single throw switches, and as a non-limiting example, the switches S1, S2 may be realized by silicon carbide metal-oxide semiconductor field-effect transistors (SiC MOSFETs).

In this implementation, the voltages V1, V2, and V3 may be DC-sourced voltages. As shown, the first switch, S1, is disposed to switchably connect the first voltage, V1, to the output, Vout, through and inductive element and the second switch, S2, is disposed to switchably couple the second voltage, V2, to the output, Vout, through an inductive element. In this implementation the two switches connect to a common node, <NUM>, and a common inductive element, L1, is disposed between the common node and an output node, Vout. Other arrangements of the inductive elements are possible. For example, there may be two separate inductive elements with one inductive element connecting S1 to Vout and another connecting S2 to Vout. In another example one inductive element may connect S1 to S2 and another inductive element may connect either S1 or S2 to Vout.

While referring to <FIG>, simultaneous reference is made to <FIG>, which depicts: <NUM>) the voltage waveform of the bias supply <NUM> that is output at Vout; <NUM>) a corresponding sheath voltage; and <NUM>) corresponding switch positions of switches S1 and S2. In operation, the first switch, S1, is closed momentarily to increase, along a first portion <NUM> of the voltage waveform (between voltage V0 and Va) a level of the voltage at the output node, Vout, to a first voltage level, Va. The level Va is maintained along a second portion <NUM> of the waveform. The second switch, S2, is then closed momentarily to decrease, along a third portion <NUM> of the waveform, the level of the voltage waveform at the output node, Vout, to a second voltage level, Vb. Note that S1 and S2 are open except for short periods of time. As shown, the negative voltage swing along the third portion <NUM> affects the sheath voltage (Vsheath); thus, a magnitude of Va-Vb may be controlled to affect the sheath voltage.

In this embodiment the third voltage, V3, is applied to the output node, Vout, through a second inductive element L2 to further decrease a level of the voltage at the output node along a fourth portion <NUM> of the voltage waveform. As shown in <FIG>, the negative voltage ramp along the fourth portion <NUM> may be established to maintain the sheath voltage by compensating for ions that impact the substrate.

Thus, S1 momentarily connects and then disconnects the first voltage, V1, to the output, Vout, through the first inductive element L1, and after a period of time, S2 connects and then disconnects the second voltage (e.g., ground) to the output, Vout, through the first inductive element L1. The third voltage, V3, is coupled to the output, Vout, through a second inductive element L2. In this implementation, the first voltage, V1, may be higher than the third voltage V3, and the momentary connection and disconnection of the first voltage, V1, to the output Vout causes the voltage of the output, Vout, to increase along the first portion <NUM> of the voltage waveform to a first voltage level, Va, and the first voltage level, Va, is sustained along the second portion of the waveform <NUM>. The first voltage level Va may be above the first voltage, V1, and the second voltage, V2, (e.g., ground) may be less than the first voltage level, Va. The momentary connecting and then disconnecting of the second voltage, V2, causes the voltage of the output, Vout, to decrease at the third portion <NUM> to the second voltage level Vb that is below the second voltage, V2 (e.g., ground).

As an example, V1 may be -<NUM> VDC; V2 may be ground; V3 may be -<NUM> VDC; V0 may be -<NUM> VDC; Vb may be -<NUM> VDC; and Va may be <NUM> VDC. But these voltages are merely exemplary to provide context to relative magnitude and polarities of the voltages described with reference to <FIG> and <FIG>.

Referring next to <FIG> shown are possible arrangements of two DC voltage sources to provide the voltages V1, V2, and V3 depicted in <FIG>. In <FIG>, V2 is grounded and forms a common node between the two DC voltage sources. In <FIG>, V1 is grounded and V2 forms a common node between the DC voltage sources. And in <FIG>, V1 is grounded and forms a common node between each of the two DC voltage sources.

In some embodiments, as shown in <FIG>, three DC voltage sources may be utilized to apply the three voltages V1, V2, and V3. As shown in <FIG>, each of the three DC voltage sources may be coupled to ground, and each of the three DC voltage sources provides a corresponding one of V1, V2, V3. In <FIG> one of the DC voltages sources is grounded and the three DC voltage sources are arranged in series. In <FIG>, one of DC voltages sources is disposed between ground and V2, and each of the DC voltage sources is coupled to V2.

The bias supply <NUM> depicted in <FIG> is merely an example of a bias supply <NUM> that may produce an output at Vout as shown in <FIG>. Other variations are shown and described in the patents referred to earlier herein. Also disclosed in the patents are different modulation schemes that may be applied to the basic source waveform (at Vout) to achieve a desired distribution of ion energies and to control average power applied to the plasma chamber by the bias supply.

One modulation scheme includes modulating the third portion <NUM> of the voltage waveform to effectuate desired ion energies of ions impinging upon the workpiece <NUM> in the plasma chamber <NUM>. As an example, the bias supply <NUM>, <NUM>, <NUM> may alternate a magnitude of the third portion <NUM> of the voltage waveform between two or more levels to effectuate an alternating surface potential of the workpiece <NUM> in the plasma between two or more distinct levels. As another example, a slope of the fourth portion <NUM> of the voltage waveform may be adjusted to change a level of current that is provided to an electrode <NUM> (to compensate for ion current that impinges upon the workpiece <NUM>) to achieve a desired spread of ion energies (e.g., around a center ion energy). Successful use of bias supplies <NUM>, <NUM>, <NUM> as a bias generator in many plasma processing systems requires careful system design.

Modulating supplies such as the source generators <NUM>, bias generators <NUM>, remote plasma sources <NUM>, and bias supplies <NUM>, <NUM>, <NUM> can cause strong modulation of plasma properties. Examples of plasma properties, without limitation, include an impedance presented by the plasma, plasma density, sheath capacitance, and a surface potential of the workpiece <NUM> in the plasma <NUM>. As discussed above, the modulation of the voltage and/or current applied by the bias supplies <NUM>, <NUM>, <NUM> is one potential cause of modulating plasma properties.

Source generators <NUM> may also modulate plasma properties by modulating electromagnetic fields impacting the plasma <NUM>. In particular, source generators may pulse the power (e.g., RF power) that is applied by a source generator <NUM>. Moreover, a magnitude of voltage of the power applied by a source generator <NUM> may be changed. The addition of one or more additional source generators <NUM> adds additional complexity. And it is also contemplated that one or more bias supplies <NUM>, <NUM>, <NUM> may modulate the voltage (Vout shown in <FIG>), and hence sheath voltage, while a source generator <NUM> is applying pulsed power. Thus, control over plasma properties (e.g., plasma density and ion energy) is challenging, and spatial control over the plasma properties is especially challenging.

As discussed above, a remote plasma source <NUM> may replace, or augment, a source generator <NUM>. But remote plasma sources <NUM> may also be modulating supplies that are configured to modulate plasma properties by modulating properties of gases in the plasma chamber <NUM>.

In addition to control challenges, one modulating supply may affect (e.g., in an adverse manner) operation of another modulating supply. As a specific, non-limiting, example, the bias supplies <NUM>, <NUM>, <NUM> may impart power at a level that results in plasma modulation, which in turn, cause undesirable changes in the load impedance presented to a source generator <NUM>. In addition, strong plasma modulation can also cause aliasing of measurements of plasma properties. The aliasing may prevent accurate measurements of forward and reflected power; thus, preventing an operator from detecting damaging power levels and/or prevent proper control over at least one of the source matching network <NUM> or the bias matching network <NUM>.

Synchronization of equipment connected to the plasma system may mitigate the adverse effects of plasma modulation (e.g., damaging power and aliasing), and as a consequence, synchronization is highly desired. But the complex, time varying, aspects of plasma modulation (e.g., resulting from potentially many modulating supplies) can make synchronization difficult.

Referring to <FIG>, shown is a synchronization controller <NUM> that is configured to synchronize constituent equipment of a plasma processing system that may include modulating supplies and other equipment that does not modulate the plasma <NUM>. As shown, the synchronization controller <NUM> includes a user interface <NUM>, a waveform-characterization module <NUM>, a waveform-repetition module <NUM>, a waveform-communication module <NUM>, and a synchronization module <NUM>.

The depicted components of the synchronization controller <NUM> may be realized by hardware, firmware, software and hardware or combinations thereof. The functional components of the synchronization controller <NUM> may be distributed about the plasma processing system and duplicated in equipment that is connected to the plasma processing system. And as discussed further herein, the synchronization controller <NUM> may be implemented as a master device or slave device.

The user interface <NUM> enables an operator to interact with the plasma processing system so that the operator may control aspects of the synchronization and the operator may receive information about conditions of the equipment and the plasma chamber <NUM>. The user interface <NUM> may be realized, for example, by one or more of a touch screen, pointing device (e.g., mouse), display, and keyboard.

The waveform-characterization module <NUM> is generally configured to generate a waveform dataset that characterizes a waveform (e.g., a waveform of a modulation of the plasma or a waveform output (or desired to be output) by equipment) of the plasma processing system. The waveform-repetition module <NUM> is configured to determine a repetition period, T, for a piece of equipment connected to the plasma system, and the waveform-communication module <NUM> is configured to communicate the waveform dataset to at least one of the piece of equipment or another piece of equipment connected to the plasma processing system. The synchronization module <NUM> is configured to send a synchronization pulse with a synchronization-pulse-repetition-period (which is an integer multiple of T) to one or more pieces of equipment connected to the plasma system.

While referring to <FIG>, simultaneous reference is made to <FIG>, which is a flowchart depicting a method that may be traversed in connection with a plasma processing system and the synchronization controller <NUM>. As shown, plasma properties are modulated with a modulating supply where the modulation has a repetition period, T (Block <NUM>). It should be recognized that in many embodiments T is the repetition period of the plasma modulation-not a cycle period of the modulating supply. As a consequence, the modulating supply may have an output with a repetition period that is different than the modulation of the plasma properties. For example, the modulating supply may have a repetition period of <NUM> microseconds and another modulating supply may have a repetition period of <NUM> microseconds resulting in the plasma <NUM> being modulated with a <NUM> millisecond repetition period, T. In some embodiments, T is a shortest length of time for which waveforms of all pieces of equipment that modulate the plasma properties of the plasma processing system is periodic with period, T.

As shown in <FIG>, the waveform characterization module <NUM> may characterize a waveform with a repetition period, T, containing at least one of information about the modulation of the plasma or a desired waveform of a piece of equipment connected to the plasma processing system to produce a waveform dataset (Block <NUM>).

Referring briefly to <FIG>, shown are: an exemplary output waveform <NUM> of the bias supply <NUM>, <NUM>, <NUM>; a waveform <NUM> corresponding to is a calculated effective voltage at the surface of the workpiece <NUM>; a corresponding synchronization signal <NUM>; and information about the waveform in the form of a waveform dataset <NUM>. In <FIG>, an output waveform <NUM> is the actual output of the bias supply bias supply <NUM>, <NUM>, <NUM> (at Vout) with a fundamental period, T, <NUM>. The waveform <NUM> is a calculated effective voltage at the surface of the workpiece <NUM> (e.g., a sheath voltage that is the voltage of the workpiece <NUM> relative to the plasma <NUM>). Also shown is a synchronization pulse <NUM> (also referred to as a synchronization signal <NUM>) with a synchronization-signal-repetition-period that is an integer multiple of T. And the waveform dataset <NUM> that includes information about the waveform <NUM>; thus, a characterized waveform (represented in <FIG>) is the waveform <NUM>. It should be recognized that the waveform <NUM> represents an alternating surface potential of the workpiece between two or more distinct levels (e.g., - 500V and -1000V), but this is only an example and is not required. Alternatively, the characterized waveform may be an output waveform generated by a modulating supply, which in <FIG> is the output waveform <NUM> of the bias supply <NUM>, <NUM>, <NUM>. In yet another implementation, the characteristics of the waveform with a repetition period T include characteristics of the plasma properties such as plasma density, sheath capacitance, sheath potential, etc..

Referring again to <FIG>, the waveform dataset <NUM> is sent by the waveform-communication module <NUM> to the at least one piece of equipment connected to the plasma system (Block <NUM>), and the synchronization module <NUM> sends the synchronization signal <NUM> with a synchronization-signal-repetition-period (which is an integer multiple of T) to at least one piece of equipment connected to the plasma system (Block <NUM>). This method enables synchronization of pieces of equipment connected to the plasma processing system where the characterized waveform contains at least one of information about the modulation of the plasma or information about a desired waveform of a piece of equipment connected to the plasma processing system. It should be recognized that the waveform dataset may be communicated to a receiving-piece of equipment to control the receiving-piece of equipment (e.g., by directing the receiving-piece of equipment to provide a desired waveform). Or the waveform dataset may be informational (e.g., to provide information about the modulation of the plasma or to provide information about an output of a modulating supply).

Although <FIG> depicts a specific example of a modulating supply that applies power with a waveform that enables control over ion energy in a region proximate to an electrode <NUM>, the waveform characterization (Block <NUM>) is generally applicable to other waveforms that may represent aspects of plasma-related modulation (e.g., plasma density, plasma impedance, ion flux, etc.) or aspects of power applied by other equipment. For example, equipment coupled to the plasma processing system may include RF and DC generators, and in some implementations, the generator(s) are able to absorb power from the plasma processing system. It is also contemplated that in some embodiments one or more generators are a load that can only absorb power from the plasma processing system. Generators that are able to absorb power are useful for controlling spatial properties of an electromagnetic field in a plasma chamber by, e.g., avoiding standing waves in the chamber.

One or more of the source generators <NUM> may synchronize a property of the output of the source generator(s) <NUM> with the characterized waveform (that has the repetition period T). The property of the output of the source generator(s) <NUM> may be at least one of voltage, current, power, frequency, or generator source impedance. And the output of the source generator(s) <NUM>, for example, may include (within one repetition period) pulsed power followed by continuous wave power. And the waveform dataset may include a time series of values indicating one or more aspects of power (e.g., voltage, current, phase, etc.) for the repetition period. The source generator <NUM> may synchronize pulsing with a particular waveform applied by the bias supply <NUM>, <NUM>, <NUM> that may, for example, modulate a magnitude of the negative voltage swing (the third portion <NUM>) in a different manner while the source generator <NUM> is pulsing as compared to when the source generator <NUM> is operating in a continuous-wave mode of operation. This use case is only an example, and various other types of processing steps may prompt synchronization among pieces of plasma processing equipment.

In addition, the source generator <NUM> may advance or delay changes in a property of the output of the source generator <NUM> with respect to changes in the characterized waveform with a repetition period T. As discussed above, the characterized waveform in some implementations may characterize the modulation of the plasma properties. The characterized waveform may also characterize a waveform of the source generator <NUM> or another modulating supply (depending upon how the source generator <NUM> is configured to operate).

The equipment coupled to the plasma processing system (and synchronized as disclosed herein) is certainly not limited to modulating supplies. For example, the at least one piece of equipment that the dataset is sent to (Block <NUM>) may include equipment that is configured to measure properties of the plasma processing system. For example, the measurements may include at least one of a measurement of plasma properties, properties of power delivered to the plasma system, or properties of gas delivered to the plasma system. By way of further example, the equipment that is configured to measure properties may include one or more of the source measurement and diagnostics system <NUM> and the bias measurement and diagnostics system <NUM>. Those of ordinary skill in the art recognize that the source measurement and diagnostics system <NUM> and the bias measurement and diagnostics system <NUM> may include one or more sensors (e.g., directional couplers and/or VI sensors) in connection with hardware to sample and analyze properties of power delivered to the plasma system (which may be used to measure plasma impedance as a plasma property). In the context of a plasma processing system utilizing the remote plasma source <NUM>, properties of the gas delivered to the plasma processing system may be measured (e.g., utilizing optical or other measurement techniques). As discussed herein, plasma modulation can cause aliasing of measurements of plasma properties, so synchronizing measurements to within time windows to avoid misleading transient values (or during time windows where modulation is at a local minima) is beneficial.

Other equipment that may be synchronized includes matching networks. For example, the impedance matching network may synchronize measurements indicative of impedance with the characterized waveform. By synchronizing the measurements with time windows where measurements are not misleading (e.g., when there not large changes in power levels applied to the plasma), matching may be improved. Examples of impedance matching networks include the source matching network <NUM> and the bias matching network <NUM>.

The waveform dataset <NUM> may be sent (Block <NUM>) via digital communication link to one or more of the pieces of equipment coupled to the plasma processing system. The communication link may include the system control bus <NUM>, which may be realized by known digital links (for example, without limitation, ethernet). In many implementations, the waveform dataset <NUM> may be communicated once, and then the synchronization pulse prompts each piece of equipment to operate in response to the waveform dataset in a repeating manner.

The synchronization signal may be sent (Block <NUM>) via the near-real-time communication link <NUM> to equipment coupled to the plasma processing system. As an example, the near-real-time link may be an analog communication link to provide a single analog output with an identifiable fundamental pulse (also referred to as a "tick")), and if required, update pulses (also referred to as "update-ticks") are sent in between the fundamental pulses. In addition, the synchronization signal may include an indication of a start of the synchronization signal repetition period as well as at least one indication that a period of time since the start of the synchronization signal repetition period has elapsed.

The start of the synchronization signal repetition period may be indicated by a pulse of a first duration and the indication that a period of time since the start of the synchronization signal repetition period has elapsed may be indicated by a pulse of a second duration that is different from the first duration. For example, the first duration may be longer than the second duration or vice versa.

In some implementations, the synchronization signal includes an indication of the start of the synchronization signal repetition period where the start of the synchronization signal repetition period is further modified at least once to indicate a time of day or to indicate that a new waveform is taking effect.

Referring to <FIG> and <FIG> shown are flowcharts depicting activities carried out at a master piece of equipment and activities carried out at a slave piece of equipment, respectively. As shown in <FIG>, at a master piece of equipment, information on desired waveforms for equipment connected to the plasma processing equipment is obtained (Block <NUM>), and a fundamental repetition period is determined (Block <NUM>). A determination is also made to establish whether any intermediate synchronization pulses are necessary to maintain accuracy (Block <NUM>). Waveform datasets are generated (Block <NUM>) and then communicated to equipment connected to the plasma processing system (Block <NUM>). In addition, synchronization pulses are provided to equipment connected to the plasma processing system (Block <NUM>). As shown, intermediate synchronization pulses are provided to equipment if necessary (Block <NUM>). And information about whether a sequence should change is also obtained (Block <NUM>), and if the sequence should change (Block <NUM>), then the activities described above with reference to Blocks <NUM> to <NUM> are performed again.

As shown in <FIG>, at a slave piece of equipment, a waveform dataset is received (Block <NUM>), and the slave then waits for a start-of-sequence pulse to be received (Block <NUM>) before setting a time to zero (Block <NUM>). The slave equipment then waits for a pulse to be received (Block <NUM>) and determines whether or not the pulse was a start-of-sequence pulse (Block <NUM>), and if so, a time is set to zero (Block <NUM>). If the received pulse is not a start-of-sequence pulse (Block <NUM>), then the time is synchronized to a timing of the received pulse (Block <NUM>). As shown, if a new waveform dataset is received (Block <NUM>), then a new-waveform-dataset-received-flag is set (Block <NUM>). If the new-waveform-dataset-received-flag is set (Block <NUM>) and the received pulse is modified to indicate a change to a new dataset (Block <NUM>), then the new-waveform-dataset-received-flag is cleared and the new waveform dataset is utilized (Block <NUM>).

By utilizing precision oscillators, synchronization can be maintained with good precision. For example, using <NUM> ppm oscillators in all equipment, a change in a waveform can be predicted with better than <NUM> ns accuracy for a fundamental pulse repetition rate as low as <NUM>. For longer pulse repetition periods one can add additional synchronization pulses every <NUM> to maintain synchronization within <NUM> ns accuracy.

Synchronization between a source generator <NUM> and bias supply <NUM>, <NUM>, <NUM> may entail lowering voltage or cutting off voltage at the end of a given bias supply pulse. For example, it may be desirable to avoid ending an RF pulse in the midst of a bias supply pulse. Alternatively, pulsing or periodic reductions in voltage, may start and end at the same point/phase in the bias supply pulse, but for different pulses. In other words, it may be desirable to set the pulse on length equal to an integer number of bias supply pulses, whether or not the envelope pulse is in phase with a start or end to an individual bias supply pulse.

The previously described embodiments provide novel and nonobvious systems and methods to create laminate films, among other use cases. Examples such as diamond like carbon, which when deposited with plasma processing has very high stresses that can result in peeling of the film, can now be processed to incorporate low stress graphite or amorphous carbon layers so that the overall film still exhibits diamond like carbon properties but at lower stresses. In some films, it may be desirable to deposit the film in one period followed by a period where the plasma chemistry is modified by pulsing control and a high bias is applied to densify the film. Aspects described herein enable production of nano-level "Bragg" structures consisting of alternative layers with different optical properties produced by combining pulsing and bias voltage control in each respective period as illustrated earlier. Said another way, a first chemistry can be achieved for a first period of time to deposit a first layer, then a second chemistry can be achieved for a second period of time to deposit a second layer. This can be repeated numerous times to achieve a "Bragg" structure. The different chemistries can be achieved by variations in one or more of: bias voltage; duty cycle of two or more bias voltages; alterations in the timing of bias voltage; source pulsing; duty cycle of source pulsing; source voltage; and source voltage and pulsing in combination.

The methods described in connection with the embodiments disclosed herein may be embodied directly in hardware, in processor-executable code encoded in a non-transitory tangible processor readable storage medium, or in a combination of the two. Referring to <FIG> for example, shown is a block diagram depicting physical components that may be utilized to realize synchronization logic that may be implemented in equipment coupled to the plasma processing systems disclosed herein. As shown, in this embodiment a display portion <NUM> and nonvolatile memory <NUM> are coupled to a bus <NUM> that is also coupled to random access memory ("RAM") <NUM>, a processing portion (which includes N processing components) <NUM>, an optional field programmable gate array (FPGA) <NUM>, and a transceiver component <NUM> that includes N transceivers. Although the components depicted in <FIG> represent physical components, <FIG> is not intended to be a detailed hardware diagram; thus many of the components depicted in <FIG> may be realized by common constructs or distributed among additional physical components. Moreover, it is contemplated that other existing and yet-to-be developed physical components and architectures may be utilized to implement the functional components described with reference to <FIG>.

This display portion <NUM> generally operates to provide a user interface for a user, and in several implementations, the display is realized by a touchscreen display. In general, the nonvolatile memory <NUM> is non-transitory memory that functions to store (e.g., persistently store) data and processor-executable code (including executable code that is associated with effectuating the methods described herein). In some embodiments for example, the nonvolatile memory <NUM> includes bootloader code, operating system code, file system code, and non-transitory processor-executable code to facilitate the execution of the methods described herein (e.g., the methods described with reference to of <FIG>, <FIG>, and <FIG>).

In many implementations, the nonvolatile memory <NUM> is realized by flash memory (e.g., NAND or ONENAND memory), but it is contemplated that other memory types may also be utilized. Although it may be possible to execute the code from the nonvolatile memory <NUM>, the executable code in the nonvolatile memory is typically loaded into RAM <NUM> and executed by one or more of the N processing components in the processing portion <NUM>.

The N processing components in connection with RAM <NUM> generally operate to execute the instructions stored in nonvolatile memory <NUM> to enable synchronization among equipment coupled to a plasma processing system. For example, non-transitory, processor-executable code to effectuate methods of synchronously pulsing and changing voltages of the source generators and bias supplies may be persistently stored in nonvolatile memory <NUM> and executed by the N processing components in connection with RAM <NUM>. As one of ordinarily skill in the art will appreciate, the processing portion <NUM> may include a video processor, digital signal processor (DSP), micro-controller, graphics processing unit (GPU), or other hardware processing components or combinations of hardware and software processing components (e.g., an FPGA or an FPGA including digital logic processing portions).

In addition, or in the alternative, the processing portion <NUM> may be configured to effectuate one or more aspects of the methodologies described herein (e.g., methods of synchronously operating equipment of a plasma processing equipment). For example, non-transitory processor-readable instructions may be stored in the nonvolatile memory <NUM> or in RAM <NUM> and when executed on the processing portion <NUM>, cause the processing portion <NUM> to perform methods of synchronously operating modulating supplies and other equipment. Alternatively, non-transitory FPGA-configuration-instructions may be persistently stored in nonvolatile memory <NUM> and accessed by the processing portion <NUM> (e.g., during boot up) to configure the hardware-configurable portions of the processing portion <NUM> to effectuate the functions disclosed herein (including the functions of the synchronization controller <NUM>.

The input component <NUM> operates to receive signals (e.g., the synchronization signals or datasets with waveform characterization data) that are indicative of one or more aspects of the synchronized control between equipment of a plasma processing system. The signals received at the input component may include, for example, the power control and data signals, or control signals from a user interface. The output component generally operates to provide one or more analog or digital signals to effectuate an operational aspect of the synchronization between the equipment. For example, the output portion <NUM> may out the synchronization signal and/or waveform datasets.

The depicted transceiver component <NUM> includes N transceiver chains, which may be used for communicating with external devices via wireless or wireline networks. Each of the N transceiver chains may represent a transceiver associated with a particular communication scheme (e.g., WiFi, Ethernet, Profibus, etc.).

Claim 1:
A control method for a plasma processing system (<NUM>), the method comprising:
modulating plasma properties with a plurality of pieces of equipment connected to the plasma processing system;
generating a plurality of waveform datasets, each of the plurality of waveform datasets characterizes a corresponding one of a plurality of output waveforms, and each of the plurality of output waveforms is output from a corresponding one of the plurality of pieces of equipment connected to the plasma processing system;
sending at least one of the plurality of waveform datasets to at least one of the plurality of pieces of equipment connected to the plasma processing system;
determining a fundamental-repetition period, Tf, that is a shortest length of time for which the plurality of output waveforms are periodic with period Tf; and
sending a synchronization signal with a synchronization signal repetition period that is an integer multiple of Tf to the at least one of the plurality of pieces of equipment connected to the plasma system.