Patent ID: 12247290

DETAILED DESCRIPTION

Hereinafter, example embodiments will be described in detail with reference to the accompanying drawings. However, the disclosure should not be construed as being limited to the embodiments described below and may be embodied in various other forms. The following examples are provided to convey the scope of aspects of the disclosure to those skilled in the art. Background information known to those skilled in the art are not provided in detail. Further, those skilled in the art would understand that modifications can be made which stall fall within the scope of the disclosure.

FIG.1is a graph showing the correlation between an ignition voltage and a pressure applied to a fluid.

The X-axis of this graph represents the product of a pressure P of the fluid supplied to a chamber510shown inFIG.4and a distance d between the electrodes. The Y-axis of this graph represents an ignition voltage V required for the fluid supplied to the chamber510shown inFIG.4to cause a discharge. That is, the ignition voltage V may represent a minimum voltage that needs to be supplied to the chamber to ignite plasma in the fluid.

Referring toFIG.1, with the distance d between the electrodes being constant, as the pressure P of the fluid is reduced, the fluid is not ionized and it may be difficult for the fluid to discharge. Therefore, the required ignition voltage V may be determined according to the pressure P of the fluid. In other words, the pressure P of the fluid and the ignition voltage V may have a proportional relationship. Since the pressure P of the fluid is proportional to the flow rate of the fluid, eventually the flow rate of the fluid and the ignition voltage V may be in a proportional relationship.

FIG.2is a graph illustrating a correlation between an ignition voltage and a flow rate of a fluid.

Referring toFIG.2, the ignition voltage increases as the flow rate of the fluid increases. In this graph, the X-axis represents the time at which a voltage starts to be supplied to the chamber510, and the Y-axis represents the ignition voltage at which the plasma starts ignition. Standard Cubic Centimeter per Minute (Sccm) is a unit indicating how many cc of gas flows per minute in a standard state, and is a unit indicating the flow rate of a fluid. In this case, the standard state may represent 0 degrees C. at a pressure of 1 atm.

According to this graph, it may be seen that the ignition voltage increases as the flow rate of the fluid increases, starting from 50 seconds after the voltage starts to be supplied to the chamber510. Therefore, as the flow rate of the fluid increases, the ignition voltage increases. Finally, measuring the ignition voltage may determine the flow rate of the fluid in the chamber.

FIG.4is a diagram for explaining a mechanism of a flow rate control method according to example embodiments. Referring toFIG.4, a matcher530adjusts an impedance so that the RF power provided from an RF power source520may be transferred to the plasma chamber510to the maximum. Since an impedance and a voltage have a proportional relationship, the impedance controlled by the matcher530and the ignition voltage supplied by the RF power source520to the chamber510may have a proportional relationship. After all, in the same principle of measuring the flow rate of the fluid in the chamber by measuring the ignition voltage, the flow rate of the fluid in the chamber may be measured by measuring the impedance controlled by the matcher530.

FIG.3is a flowchart of a flow rate control method according to example embodiments.

Referring toFIG.3, the flow rate control method using a plasma system includes supplying a fluid from a valve (S100), measuring a flow rate of the fluid based on a first temperature and a second temperature of the fluid (S200), supplying a voltage to the chamber through an RF power source after supplying the fluid to the chamber (S300), transmitting the voltage to the controller after measuring the voltage in a third sensor (S400), and comparing the voltage with a reference voltage in the controller (S500). In the operation of S200, if the flow rate of the fluid determined based on the first temperature and the second temperature in S200is in a normal range (e.g., when the flow rate of the fluid is lower than a reference flow rate), the flow rate control method proceeds to S300, and if the flow rate of the fluid determined in S200is in an error range (e.g., when the flow rate of the fluid is higher than the reference flow rate), the flow rate control method proceeds to S700, in which the controller transmits a signal to stop supplying the fluid to the valve.

According to an example embodiment, the flow rate control method using plasma may further include, after comparing the voltage to the reference voltage in the controller in S500, determining whether the voltage is higher than a reference voltage and transmitting a feedback signal to the valve (S600). The voltages referred to in S300, S400, S500, and S600represent the ignition voltage, which is the minimum voltage that is required to be supplied to the chamber to ignite the fluid into plasma. When the ignition voltage is lower than the reference voltage, the controller may transmit a supply signal of the fluid to the valve so that the fluid continues to be supplied from the valve in S100. When the ignition voltage is higher than the reference voltage, the controller may transmit a signal to stop supplying the fluid to the valve (S700). Each of the above operations will be described in detail later with reference toFIG.6.

Referring back toFIG.4, the controller100may transmit a fluid supply signal to the valve210. Thereafter, the valve210may supply the fluid to a first sensor310. In this case, the flow rate of the fluid supplied by the valve210to the first sensor310may be 3 sccm to 20 sccm. In addition, the fluid may include titanium tetrachloride (TiCl4), but is not necessarily limited to the above material.

The valve210may be configured to control the flow rate of the fluid. The type of the valve210is various, and the type of the valve210may be easily selected by a person skilled in the art. For example, if the exhaust line connectable to the valve210is a curved exhaust line, a bellows-type valve may be used. The bellows-type valve may be installed adjacent to the bent part of the exhaust line, and a solenoid or pneumatic device may be used as a power source for contracting or extending the bellows-type valve.

According to an example embodiment, a piezo valve may be used to control the flow rate of the fluid. When a voltage is applied to a stacked piezoelectric element of the piezoelectric valve, the displacement in the extension direction of the stacked piezoelectric element is transmitted to the valve body through the displacement expansion mechanism, and the valve body may be moved quickly to open the valve. In addition, when the voltage application to the stacked piezoelectric element is released, the return force accompanying the return of the stacked piezoelectric element to its original state is transmitted to the valve body through the displacement expansion mechanism, and closes the valve by quickly abutting its valve body against the valve seat. Although a bellows type valve and a piezo valve have been described in detail above as the type of the valve210, the valve210is not necessarily limited to the above type.

According to an example embodiment, a first heater212may be connected to the valve210, and the first heater212may vaporize a fluid supplied through the valve210. Therefore, the valve210may supply the fluid in a gas state to the first sensor310.

The first sensor310supplied with the fluid from the valve210may measure a first temperature of the fluid. The first sensor310may be connected to a first resistor312and may use the resistance of the first resistor312in the process of measuring the first temperature of the fluid. Thereafter, the first sensor310may transmit a value of the first temperature to the controller100. After transmitting the value of the first temperature to the controller100, the first sensor310may supply the fluid to a second heater320. The second heater320may supply heat to the first sensor310. According to an example embodiment, the fluid in a gaseous state supplied with heat from the second heater320may be supplied to a second sensor330. Thereafter, the second sensor330may measure a second temperature of the fluid. The second sensor330may be connected to a second resistor332, and the resistance of the second resistor332may be used in the process of measuring the second temperature of the fluid. Thereafter, the second sensor330may transmit a value of the second temperature to the controller100. The controller100may compare the first temperature with the second temperature to first determine the flow rate of the fluid. In this case, the fluid of which the flow rate is to be determined may be a fluid in a gas state. A detailed description of a process in which the first sensor310and the second sensor330respectively measure the first temperature and the second temperature will be described later with reference toFIGS.6and7.

According to an example embodiment, the fluid may be supplied from the second sensor330to a gas line410. A third heater412and a divert line414may be connected to the gas line410. The third heater412may be configured to supply heat for smooth movement of the fluid. The divert line414may be an example of an additional device configured to control an accurate flow rate of a fluid. Specifically, a fluid may be supplied from the gas line410to the chamber510. In this case, to smoothly supply the fluid from the gas line410to the chamber510, a carrier gas for moving the fluid into the chamber may be supplied. The divert line414may be configured to minimize a change in the flow rate of the fluid after the fluid is supplied to the chamber510by the carrier gas. For example, the divert line414may have a structure for diverting only the fluid, a structure for enabling pressure control of the divert line414, or a structure for dividing and flowing a carrier gas. According to an example embodiment, the fluid may be supplied to the chamber510through the gas line410. The chamber510may be connected to the RF power source520and the matcher530. The fluid may be in a plasma state by receiving a voltage from the RF power source520in the chamber510, and a detailed process for this will be described later with reference toFIG.7.

The RF power source520may supply an ignition voltage to the chamber510, and a third sensor610may be configured to measure the ignition voltage. The third sensor610may be a voltage-current probe (V-I probe). The V-I probe may be inserted into the power line between the electrode or coil used for plasma generation and the matcher530, and may refer to a diagnostic device that views the entire plasma reactor as a kind of equivalent circuit and measures changes in electrical characteristics in the plasma reactor. The plasma reactor referred to herein may be a term referring to an entire system including an electrode, a coil, or a plasma chamber. The V-I probe may measure voltage, current, phase difference, reflected power, etc. of harmonics, and display a measurement result of the harmonics through a fast Fourier transform. Physical quantities, such as voltage, current, phase difference, and reflected power listed above, may react very sensitively to the state of the plasma reactor. That is, changes in the plasma density, electron temperature, composition of substances present in the plasma, or even small changes in the reactor surface state may affect the measured values. Also, the third sensor610may measure an impedance adjusted by the matcher530, which will be described later.

The matcher530may maximize the RF power delivery of the RF power source520by adjusting impedance so that a complex conjugate condition is satisfied based on a maximum power delivery theory.

According to an example embodiment, the state of the fluid supplied to the chamber510through the gas line410may be a liquid state, a gaseous state, an aerosol state, or a combination thereof. The RF power source520supplies an ignition voltage to the chamber510, and the fluid may be put into a plasma state. The third sensor610may measure the ignition voltage supplied by the RF power source520. Thereafter, the third sensor610may transmit the measured value of the ignition voltage to the controller100. The controller100may secondarily determine the flow rate of the fluid using the correlation between the ignition voltage and the flow rate of the fluid described with reference toFIGS.2and3. In this case, the fluid to be determined secondarily may be in a liquid state, a gas state, an aerosol state, or a state of a combination thereof.

According to an example embodiment, the controller100may compare the ignition voltage with a reference voltage to secondarily determine the flow rate of the fluid. The reference voltage may be a voltage set by the controller100to compare with any arbitrary voltage. In this case, the reference voltage may be 1 V to 100 V. When the ignition voltage is higher than the reference voltage, the flow rate of the fluid may be in a high state, and when the ignition voltage is lower than the reference voltage, the flow rate of the fluid may be in a low state.

The controller100may transmit a feedback signal to the valve210based on secondary measurement of the flow rate of the fluid by comparing the ignition voltage to the reference voltage. Specifically, when the ignition voltage is lower than the reference voltage, the controller100may transmit a fluid supply signal to the valve210. Accordingly, the valve210may continuously supply the fluid. When the ignition voltage is higher than the reference voltage, the controller100may transmit a signal to stop supplying the fluid to the valve210. As a result, the flow rate of the fluid may be controlled using the feedback signal of the controller100.

According to another embodiment, the RF power source520may supply an ignition voltage to the chamber510and the fluid may be in a plasma state. In this case, the matcher530adjusts impedance so that the RF power from the RF power source520may be transferred to the plasma chamber510to the maximum. That is, the impedance controlled by the matcher530and the ignition voltage supplied by the RF power source520may have a proportional relationship. The third sensor610may measure the impedance adjusted by the matcher530. Thereafter, the third sensor610may transmit the measured impedance value to the controller100. The controller100may secondarily determine the flow rate of the fluid using the correlation between the impedance and the flow rate of the fluid. In this case, the fluid to be measured secondarily may be in a liquid state, a gas state, an aerosol state, or a state of a combination thereof.

The controller100may compare the impedance to a reference impedance to secondarily determine the flow rate of the fluid. The reference impedance may be an impedance set by the controller100to compare with any arbitrary impedance. That is, when the impedance is higher than the reference impedance, the flow rate of the fluid may be in a high state, and when the impedance is lower than the reference impedance, the flow rate of the fluid may be in a low state.

The controller100may transmit a feedback signal to the valve210after secondary measurement of the flow rate of the fluid by comparing the impedance with the reference impedance. Specifically, when the impedance is lower than the reference impedance, the controller100may transmit a fluid supply signal to the valve210. Accordingly, the valve210may continuously supply the fluid. When the impedance is higher than the reference impedance, the controller100may transmit a signal to stop the supply of the fluid to the valve210. As a result, the flow rate of the fluid may be controlled using the feedback signal of the controller100.

FIG.5is a configuration diagram of a plasma processing system according to embodiments.

Referring toFIG.5, the plasma processing system1000of this embodiment may include a radio frequency (RF) power source520, a matcher530, a plasma control circuit540, a transmission line600, and a chamber510.

The RF power source520may generate and supply RF power to the chamber510. The RF power source520may generate and output RF power of various frequencies. For example, the RF power source520may include three sources, for example, a first source522, a second source524, and a third source526. Here, the first source522may generate RF power having a first frequency F1HMz in the range of several MHz to several tens of MHz. The second source524may generate RF power having a second frequency F2MHz in the range of several hundred kHz to several MHz. The third source526may generate RF power having a third frequency F3kHz in the range of several tens of kHz to several hundreds of kHz. In addition, each of the three sources, that is, the first source522, the second source524, and the third source526, of the RF power source520may generate and output power of several hundred to tens of thousands of watts (W). In the plasma processing system1000of an example embodiment, the RF power source520includes three sources, that is, the first source522, the second source524, and the third source526, but the number of sources included in the RF power source520is not limited to three. For example, the RF power source520may include two or more sources. In addition, the frequency range and power of the RF power generated by the source is not limited to the above-described numerical values. For example, according to an example embodiment, at least one source included in the RF power source520may generate RF power having a frequency of several tens of kHz or less or several hundred MHz or more. In addition, at least one source included in the RF power source520may generate RF power having a power of several hundred watts or less or several thousand watts or more.

For reference, in the plasma processing system1000of an example embodiment, the RF power source520may correspond to a power source for supplying power to the chamber510. Also, the chamber510may be viewed as a kind of load receiving power from the RF power source520. According to an example embodiment, in the plasma processing system1000, the RF power source520may include at least six sources to generate RF power of various frequencies and supply the generated RF power to the plasma chamber510. Through this, ion energy and plasma density of the plasma chamber510may be independently controlled. For example, in an example in which the RF power source520includes three sources, that is, the first source522, the second source524, and the third source526, the high frequency RF power from the first source522may generate plasma, and the low frequency RF power from the third source526may energize ions. Meanwhile, the RF power of the intermediate frequency from the second source524may have a different function depending on an embodiment. For example, the RF power of the second source524may improve the functionality of the RF power from the first source522and/or the RF power from the third source526. Meanwhile, to improve an etch rate and an etch profile by plasma in the chamber510, RF power may be applied in as a pulse. The number of the second source524that provides the RF poser of the intermediate frequency is not limited.

The matcher530adjusts the impedance so that the RF power from the RF power source520may be transferred to the plasma chamber510to the maximum. For example, the matcher530may maximize RF power delivery by adjusting the impedance so that a complex conjugate condition is satisfied based on a maximum power delivery theory. For example, by driving the RF power source520in an environment of 50Ω so that reflected power is minimized, the matcher530may function to maximize the RF power from the RF power source520to the chamber510. The matcher530may include three sub matchers, for example, first, second and third sub matchers532,534, and536, corresponding to each frequency of the RF power. For example, the matcher530may include the first sub matcher532corresponding to a first frequency F1MHz of the first source522, the second sub matcher534corresponding to a second frequency F2MHz of the second source524, and the third sub matcher536corresponding to the third frequency F3kHz of the third source526. Each of the three sub matchers, that is, the first, second, and third sub matcher532,534, and536, may adjust the impedance so that RF power of the corresponding frequency is transmitted to the plasma chamber510to the maximum.

The plasma control circuit540may selectively and/or independently control harmonics of a very high frequency (VHF) among frequencies of RF power to control and adjust the plasma distribution within the chamber510. For example, the plasma control circuit540may selectively and/or independently control harmonics of a very high frequency in the first frequency F1MHz of the first source522to control and adjust the plasma distribution in the chamber510. Here, the plasma distribution may refer to a plasma density distribution. Meanwhile, only the plasma control circuit540may be treated as a plasma control apparatus (PCA) that controls plasma distribution in the chamber510. Alternatively, according to an example embodiment, since the plasma control circuit540creates resonance together with the impedance of the matcher530and the transmission line600, the PCA may include the matcher530and the transmission line600together with the plasma control circuit540as components. In other words, the plasma control device PCA may include the matcher530, the plasma control circuit540, and the transmission line600.

The transmission line600may be disposed between the matcher530and the chamber510to transmit RF power to the chamber510. Meanwhile, in an example embodiment, since the plasma control circuit540is disposed as an output terminal of the matcher530, the transmission line600may be considered to be disposed between the plasma control circuit540and the chamber510. Although not specifically illustrated, the transmission line600may also be disposed between the RF power source520and the matcher530.

The transmission line600may be implemented as, for example, a coax cable, an RF strap, an RF rod, or the like. A coaxial cable may include a center conductor, an outer conductor, an insulator, and a sheath. The coaxial cable may have a structure in which a center conductor and an outer conductor are coaxially arranged. In general, coaxial cables have low attenuation up to high frequencies and are therefore suitable for broadband transmission, and may also have low leakage due to the presence of external conductors. Accordingly, the coaxial cable may be mainly used as a transmission cable used when the frequency is high. For example, the coaxial cable may effectively transmit RF power having a frequency in the range of several MHz to several tens of MHz without leakage. On the other hand, there are two types of coaxial cables with characteristic impedances of 50Ω and 75Ω.

The RF strap may include a strap conductor, a ground housing, and an insulator. The strap conductor may have a band-like shape extending in one direction. The ground housing may have the form of a circular tube surrounding the strap conductor at a preset distance. The ground housing may protect the strap conductor from RF radiation. On the other hand, an insulator may fill between the strap conductor and the ground housing. The RF rod may be structurally different from an RF strap in that the RF rod includes a rod conductor instead of a strap conductor. Specifically, the rod conductor of the RF rod may have a cylindrical shape extending in one direction. Such an RF strap or RF rod may deliver RF power having a frequency in the range of, for example, several MHz to several tens of MHz.

The impedance characteristic of the transmission line600may be changed by changing the physical characteristics of the implemented coaxial cable, RF strap, RF rod, and the like. For example, when the transmission line600is implemented as a coaxial cable, the impedance characteristic of the transmission line600may be changed by changing the length of the coaxial cable. In addition, when the transmission line600is implemented as an RF strap or RF rod, the impedance characteristics of the transmission line600may be changed by changing the length of the strap conductor or the rod conductor, changing the spatial size of the ground housing, or changing the dielectric constant and/or permeability of the insulator.

The chamber510may include a chamber body512, an electrostatic chuck514, and a shower head516. The chamber510is a chamber for a plasma process, and plasma P may be generated therein. The chamber510may be a capacitively coupled plasma (CCP) chamber, an inductively coupled plasma (ICP) chamber, or a mixed CCP and ICP chamber. Of course, the chamber510is not limited to the aforementioned chambers. For reference, depending on the type of plasma chamber and the type of RF power applied to the plasma chamber, the plasma process system may be classified into a CCP method, an ICP method, and a CCP and ICP combined method. The plasma processing system1000of an example embodiment may be a CCP method or an ICP method. In addition, the plasma processing system1000of an example embodiment may be implemented using a CCP and ICP combined method.

The chamber body512may limit a reaction space in which plasma is formed to seal the reaction space from the outside. The chamber body512is generally formed of a metal material, and may maintain a ground state to block noise from the outside during a plasma process. A gas inlet, a gas outlet, a viewport, and the like may be formed in the chamber body512. A process gas required for the plasma process may be supplied through the gas inlet. Here, the process gas may refer to all gases required in the plasma process, such as a source gas, a reaction gas, and a purge gas. After the plasma process through the gas outlet, gases in the plasma chamber510may be exhausted to the outside. Also, the pressure inside the plasma chamber510may be adjusted through the gas outlet. Meanwhile, one or more viewports may be formed in the chamber body512, and the inside of the plasma chamber510may be monitored through the viewports.

The electrostatic chuck514may be disposed at a lower portion inside the plasma chamber510. A wafer2000to be subjected to a plasma process may be disposed and fixed on the upper surface of the electrostatic chuck514. The electrostatic chuck514may hold the wafer2000by electrostatic force. Also, the electrostatic chuck514may include a bottom electrode for a plasma process. The electrostatic chuck514may be connected to the RF power source520through the transmission line600. Accordingly, RF power from the RF power source520may be applied into the plasma chamber510through the electrostatic chuck514. The shower head516may be disposed at an upper portion inside the plasma chamber510. The shower head516may inject process gases supplied through a gas inlet through a plurality of injection holes into the plasma chamber510. Meanwhile, the shower head516may include a top electrode. The shower head516may be connected to ground in a plasma process, for example.

The plasma processing system1000may include at least one RF sensor. The RF sensor may be the third sensor610illustrated inFIG.4. The RF sensor may be disposed at the output terminal of the RF power source100or the input terminal or output terminal of the matcher200to measure RF power delivered to the chamber510and/or the impedance of the chamber510. By monitoring the state of the chamber510through the RF sensor, it is possible to effectively manage and control the transfer of RF power to the plasma chamber510, and accordingly, the plasma process may be precisely performed.

The plasma processing system1000of an example embodiment includes the plasma control circuit540to create resonance with respect to harmonics of very short waves among frequencies of RF power delivered to the chamber510so that plasma distribution in the chamber510may be uniformly controlled and adjusted. Accordingly, the deposition process on the wafer2000, which is the target of the plasma process, may be uniformly performed.

FIG.6is a schematic configuration diagram for explaining an example embodiment of the sensor shown inFIG.4. Specifically,FIG.6is a configuration diagram for explaining the operation principle of the first sensor310and the second sensor330shown inFIG.6.

The first sensor310may include a first resistor312and a portion of a bridge circuit342. The second sensor33may include a second resistor332and another portion of the bridge circuit342. Some of the fluid in the gas state flowing along the exhaust line may be input to the inlet of the U-shaped tube and discharged to the outlet of the U-shaped tube. The first resistor312may be wound around the inlet portion of the U-shaped tube, and the second resistor332may be wound around the outlet portion of the U-shaped tube. Both the first resistor312and the second resistor332may be connected to the bridge circuit342. The first resistor312and the second resistor332may each include a coil for generating heat. The second heater320may be connected between the first resistor312and the second resistor332in the U-shaped tube. The second heater320may be configured to supply heat to the gaseous fluid that has passed through the region in which the first resistor312is wound in the U-shaped tube.

Heat generated from the first resistor312may be lost corresponding to the flow rate of the fluid flowing into the U-shaped tube. Heat generated from the second resistor332may be lost in response to the flow rate of the fluid supplied with heat from the second heater320. The first resistor312and the second resistor332may each have a resistance value corresponding to the lost heat. The first resistor312and the second resistor332may be connected to the bridge circuit342to serve as one resistor, respectively. Accordingly, the first sensor310may measure the first temperature of the fluid based on the resistance value of the first resistor312corresponding to the lost heat. Also, the second sensor330may measure the second temperature of the fluid based on the resistance value of the second resistor332corresponding to the lost heat. The controller100may determine the flow rate of the fluid by comparing the first temperature measured by the first sensor310with the second temperature measured by the second sensor330. For example, the flow rate of the fluid may be determined through heat conduction of the gaseous fluid, but the method is not limited thereto. The controller100may transmit a signal to stop the supply of the fluid to the valve210when the flow rate of the fluid is higher than a reference flow rate.

FIG.7is a schematic configuration diagram for explaining an example embodiment of the sensor shown inFIG.4. The sensor710according to an example embodiment may determine the flow rate by using the fact that the propagation speed of ultrasonic waves is different when the fluid is stopped and when the fluid is flowing. The sensor710described in this embodiment may be otherwise referred to as an ultrasonic sensor. The sensor710may include a transmitter712and a receiver732. The transmitter712may be disposed in a transmission area710, and the receiver732may be disposed in a reception area730. The transmitter712and the receiver732may be arranged side by side in the gas flow direction inside the exhaust line. Both the transmitter712and the receiver732may be connected to the controller100. The transmitter712may emit ultrasonic waves while the fluid discharged from the chamber510flows through the exhaust line. Ultrasonic waves emitted from the transmitter712may be received by the receiver732. The controller100may measure the time (hereinafter, referred to as flow time) that the ultrasonic wave emitted from the transmitter712is received by the receiver732. In the controller100, a flow time when gas does not flow in the exhaust line (hereinafter referred to as a reference time) and a flow rate of gas when gas normally flows in the exhaust line are preset. The controller100may calculate the flow rate of the gas currently flowing through the exhaust line by comparing the reference time to the measured flow time. Then, when the calculated flow rate and the preset flow rate exceed an error range, the controller100may transmit a signal to stop supplying the fluid to the valve.

At least one of the components, elements, modules or units (collectively “components” in this paragraph) represented by a block in the drawings may be embodied as various numbers of hardware, software and/or firmware structures that execute respective functions described above, according to an example embodiment. According to example embodiments, at least one of these components may use a direct circuit structure, such as a memory, a processor, a logic circuit, a look-up table, etc. that may execute the respective functions through controls of one or more microprocessors or other control apparatuses. Also, at least one of these components may be specifically embodied by a module, a program, or a part of code, which contains one or more executable instructions for performing specified logic functions, and executed by one or more microprocessors or other control apparatuses. Further, at least one of these components may include or may be implemented by a processor such as a central processing unit (CPU) that performs the respective functions, a microprocessor, or the like. Two or more of these components may be combined into one single component which performs all operations or functions of the combined two or more components. Also, at least part of functions of at least one of these components may be performed by another of these components. Functional aspects of the above exemplary embodiments may be implemented in algorithms that execute on one or more processors. Furthermore, the components represented by a block or processing steps may employ any number of related art techniques for electronics configuration, signal processing and/or control, data processing and the like.

While example embodiments been particularly shown and described with reference to the drawings, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims and their equivalents.