Patent Publication Number: US-2023154729-A1

Title: Plasma processing apparatus and method of manufacturing semiconductor device by using same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0158038, filed on Nov. 16, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
     BACKGROUND 
     The disclosure relates to a plasma processing apparatus and a method of manufacturing a semiconductor device by using the same, and more particularly, to a plasma processing apparatus for controlling a distribution of plasma inside a plasma chamber and a method of manufacturing a semiconductor device by using the same. 
     In general, a series of processes, such as deposition, etching, and cleaning, may be performed to manufacture semiconductor devices. The processes may be performed via a deposition, etching, or cleaning apparatus having a process chamber. Plasma technology, such as capacitively coupled plasma (CCP), inductively coupled plasma (ICP), or a combination of CCP and ICP, has been used to improve selectivity and minimize film quality damage. Examples of the plasma technology include direct plasma technology for directly generating plasma inside a process chamber that is a wafer processing space, and remote plasma technology for generating plasma outside a process chamber and supplying the generated plasma into the process chamber. 
     SUMMARY 
     Example embodiments of the disclosure provide a plasma processing apparatus for temporally and spatially controlling a distribution of plasma inside a plasma chamber and a method of manufacturing a semiconductor device by using the same. 
     According to an aspect of an example embodiment, a plasma processing apparatus includes: a plasma chamber including a first area including and a second area separated from the first area; an electrostatic chuck provided in the first area of the plasma chamber, and configured to support a wafer; a first radio frequency (RF) power source configured to transmit pieces of first RF power to the first area, wherein a first piece of the pieces of first RF power has a first frequency and a second piece of the pieces of the first RF power has a second frequency different from the first frequency; a second RF power source configured to transmit second RF power to the second area of the plasma chamber; a controller configured to control the first RF power source and the second RF power source; and a first coil and a second coil arranged in the second area, wherein the first coil and the second coil are positioned in a same plane and the first coil surrounds the second coil, and wherein the controller is further configured to: spatially control plasma in the first area and the second area by controlling a signal of a current applied to the first coil and a signal of a current applied to the second coil, and temporally control the plasma in the first area and the second area by controlling at least one of a signal of the pieces of first RF power transmitted from the first RF power source or a signal of the second RF power transmitted from the second RF power source. 
     According to an aspect of an example embodiment, a plasma processing apparatus includes: a plasma chamber including a first area and a second area separated from the first area; an electrostatic chuck provided in the first area of the plasma chamber, and configured to support a wafer; a ring-shaped edge ring surrounding the electrostatic chuck; an insulating isolation provided at a lower portion of the electrostatic chuck, and configured to insulate the electrostatic chuck; a first radio frequency (RF) power source configured to transmit pieces of first RF power to the first area, wherein a first piece of the plurality of pieces of first RF power has a first frequency and a second piece of the pieces of first RF power has a second frequency different from the first frequency; a second RF power source configured to transmit second RF power to the second area; a distribution plate arranged inside the plasma chamber, the distribution plate including a gas hole and an ion filter configured to filter plasma; a controller configured to control the first RF power source and the second RF power source; and a first coil and a second coil arranged in the second area, wherein the first coil and the second coil are positioned in a same plane and the first coil surrounds the second coil, and wherein the controller is further configured to: spatially control the plasma in the first area and the second area by controlling a signal of a current applied to the first coil and a signal of a current applied to the second coil, and temporally control the plasma in the first area and the second area by controlling at least one of a signal of the pieces of the first RF power transmitted from the first RF power source or a signal of of the second RF power transmitted from the second RF power source. 
     According to an aspect of an example embodiment, a method of manufacturing a semiconductor device, includes: loading a wafer onto an electrostatic chuck inside a plasma chamber including a first area and a second area, wherein a first coil and a second coil, which are spatially separated from each other, are arranged in the second area; injecting a process gas into the plasma chamber; generating plasma by supplying second radio frequency (RF) power to the second area of the plasma chamber; processing the wafer by supplying pieces of first RF power to the first area of the plasma chamber; and unloading the wafer from the electrostatic chuck, wherein a signal of a current applied to the first coil and a signal of a current applied to the second coil are controlled such that the plasma in the first area or the second area is spatially controlled, and wherein at least one of a signal of the pieces of first RF power or a signal of the second RF power is controlled such that the plasma in the first area or the second area is temporally controlled. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages will be more apparent from the following detailed description of certain example embodiments taken in conjunction with the accompanying drawings in which: 
         FIGS.  1 A and  1 B  are respectively a block diagram and a circuit diagram of a plasma processing apparatus according to an example embodiment; 
         FIGS.  2 A to  2 D  are graphs illustrating, over time, an intensity of a signal applied to a first coil, an intensity of a signal applied to a second coil, and an intensity of a signal applied from a first radio frequency (RF) power source, according to example embodiments; 
         FIGS.  3 A and  3 B  are graphs illustrating distributions of a process gas in a space inside a plasma chamber, according to an example embodiment; 
         FIG.  4    is a block diagram of a plasma processing apparatus according to an example embodiment; 
         FIG.  5    is a block diagram of a plasma processing apparatus according to an example embodiment; and 
         FIG.  6    is a flowchart illustrating a method of manufacturing a semiconductor device, according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, example embodiments will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements, and thus their description will be omitted. 
       FIGS.  1 A and  1 B  are respectively a block diagram and a circuit diagram of a plasma processing apparatus  1000  according to an example embodiment. 
     Referring to  FIGS.  1 A and  1 B , the plasma processing apparatus  1000  according to the example embodiment may include a radio frequency (RF) power source  100 , a matcher  200 , a controller  300 , a transmission line  400 , and a plasma chamber  500 . 
     In  FIG.  1 A , arrows may indicate a travel path of plasma inside a chamber body  510  of the plasma chamber  500 . 
     The plasma processing apparatus  1000  may be configured to generate plasma. The plasma processing apparatus  1000  may include a capacitively coupled plasma (CCP) source, an inductively coupled plasma (ICP) source, a microwave plasma source, a remote plasma source, and the like. 
     The plasma processing apparatus  1000  may be an apparatus for processing a wafer  2000  by using generated plasma. The plasma processing apparatus  1000  may perform, on the wafer  2000 , one of plasma annealing, plasma etching, plasma enhanced chemical vapor deposition, sputtering, and plasma cleaning. 
     In an example, the plasma processing apparatus  1000  may perform, for example, an isotropic etching process on the wafer  2000 . The plasma processing apparatus  1000  may perform a process of substituting silicon oxide formed on the wafer  2000  with ammonium hexafluorosilicate ((NH 4 ) 2 SiF 6 ) and removing the ammonium hexafluorosilicate ((NH 4 ) 2 SiF 6 ) via annealing. 
     As an example, the plasma processing apparatus  1000  may perform a process of isotropically removing any one of crystalline and/or amorphous silicon, silicon nitride, and metal on the wafer  200  by alternately and repeatedly performing plasma processing and annealing processing on any one of the crystalline and/or amorphous silicon, the silicon nitride, and the metal. 
     The wafer  2000  may include, for example, silicon (Si). The wafer  2000  may include a semiconductor element such germanium (Ge), or a compound semiconductor such as silicon carbide (SiC), gallium arsenide (GaAs), indium arsenide (InAs), or indium phosphide (InP). According to some embodiments, the wafer  2000  may have a silicon on insulator (SOI) structure. In addition, the wafer  2000  may include a buried oxide layer. According to some embodiments, the wafer  2000  may include a conductive region, e.g., a well doped with impurities. According to some embodiments, the wafer  2000  may have various device isolation structures, such as shallow trench isolation (STI), which isolate the doped wells from each other. 
     Here, the wafer  2000  may have a diameter of about 300 mm, but is not limited thereto. The diameter of the wafer  2000  may be, for example, about 150 mm, about 200 mm, about 450 mm, or more. 
     The RF power source  100  may generate RF power and supply the generated RF power to the plasma chamber  500 . The RF power source  100  may generate and output pieces of RF power having various frequencies. For example, the RF power source  100  may include four sources, for example, a first source  110 , a second source  120 , a third source  130 , and a fourth source  140 . Here, the first source  110  may generate a piece of RF power having a first frequency F 1  MHz (e.g., a first piece of RF power) in the range of several MHz to several tens of MHz. The second source  120  may generate a piece of RF power having a second frequency F 2  MHz (e.g., a second piece of RF power) in the range of several hundred kHz to several MHz. The third source  130  may generate a piece of RF power having a third frequency F 3  kHz in the range of several tens of kHz to several hundred kHz. Also, the fourth source  140  may generate a piece of RF power having a fourth frequency F 4  MHz in the range of several MHz to several tens of MHz. In addition, each of the first, second, third, and fourth sources  110 ,  120 ,  130 , and  140  of the RF power source  100  may generate and output power of several hundreds to tens of thousands of watts (W). 
     Although described later, RF power from the first, second, and third sources  110 ,  120 , and  130  may be applied to a first area A 1  of the plasma chamber  500 , and RF power from the fourth source  140  may be applied to a second area A 2  of the plasma chamber  500 . 
     For example, the first source  110  may generate RF power having a frequency in the range of about 40 MHz to about 60 MHz, and the second source  120  may generate RF power having a frequency in the range of about 400 kHz to about 2 MHz. Also, the third source  130  may generate RF power having a frequency in the range of about 10 kHz to about 800 kHz, and the fourth source  140  may generate RF power having a frequency in the range of about 13 MHz to about 27 MHz. 
     In the plasma processing apparatus  1000  of an example embodiment, the RF power source  100  illustratively includes the first, second, third, and fourth sources  110 ,  120 ,  130 , and  140 , but the number of sources included in the RF power source  100  is not limited to four. For example, the RF power source  100  may include three or fewer sources, or five or more sources. In addition, a frequency range and power of RF power generated by the RF power source  100  are not limited to the frequency ranges and power described above. For example, according to embodiments, at least one source included in the RF power source  100  may generate RF power having a frequency of several tens of kHz or less, or several hundred MHz or more. Also, at least one source included in the RF power source  100  may generate RF power having power of several hundred watts or less, or several thousand watts or more. 
     In addition,  FIG.  1 A  illustrates that the first, second, and third sources  110 ,  120 , and  130  each supply RF power to the first area A 1 , and the fourth source  140  supplies RF power to the second area A 2 . However, the number of sources connected to each area may be variously modified. For example, two sources, or four or more sources may be connected to the first area A 1 , and two or more sources may be connected to the second area A 2 . 
     For example, the first, second, and third sources  110 ,  120 , and  130  may be connected to an electrostatic chuck  530  of the plasma chamber  500 , and the fourth source  140  may be connected to first and second coils  551  and  552  of the plasma chamber  500 . In another example embodiment, the fourth source  140  may be connected to a conductive plate ( 590  of  FIG.  4   ) of the plasma chamber  500 . 
     The RF power source  100  may include a first RF power source  100   a  and a second RF power source  100   b.  The first RF power source  100   a  may include the first, second, and third sources  110 ,  120 , and  130 , and the second RF power source  100   b  may include the fourth source  140 . The first RF power source  100   a  may be applied to the first area A 1 , for example, the electrostatic chuck  530 . The second RF power source  100   b  may be applied to the second area A 2 , for example, the first and second coils  551  and  552 . 
     For reference, in the plasma processing apparatus  1000  of the example embodiment, the RF power source  100  may correspond to a power source for supplying power to the plasma chamber  500 . Also, the plasma chamber  500  may be referred to as a kind of load supplied with power from the RF power source  100 . Accordingly, in the circuit diagram of  FIG.  1 B , the plasma chamber  500  is represented by a capacitor element as a load. 
     In the plasma processing apparatus  1000  of the example embodiment, the RF power source  100  may include at least two sources to generate pieces of RF power having various frequencies and supply the generated pieces of RF power to the plasma chamber  500 . Accordingly, energy of ions and a density of plasma inside the plasma chamber  500  may be independently controlled. For example, when the RF power source  100  including the first, second, third, and fourth sources  110 ,  120 ,  130 , and  140  is described in more detail, pieces of high-frequency RF power from the first and fourth sources  110  and  140  may generate plasma, and pieces of low-frequency RF power from the second source  120  or the third source  130  may supply energy to ions. 
     Intermediate frequency RF power from the second source  120  may have a function varying according to embodiments. For example, RF power from the second source  120  may enhance functions of pieces of RF power from the first, third, and/or the fourth sources  110 ,  130 , and/or  140 . Pieces of RF power may be applied in the form of pulses to improve an etch rate and an etch profile by plasma within the plasma chamber  500 . 
     The plasma processing apparatus  1000  may include the matcher  200 . The matcher  200  may allow pieces of RF power from the RF power source  100  to be maximally delivered to the plasma chamber  500  by adjusting impedance. For example, the matcher  200  may maximize RF power delivery by adjusting impedance so that a complex conjugate condition is satisfied on the basis of a maximum power delivery theory. In other words, the matcher  200  may allow pieces of RF power from the RF power source  100  to be maximally delivered to the plasma chamber  500  by driving the RF power source  100  in an environment of 50Ω so that reflected power is minimized. 
     The matcher  200  may include first, second, third, and fourth sub matchers  210 ,  220 ,  230 , and  240  corresponding to respective frequencies of pieces of RF power. For example, the matcher  200  may include the first sub matcher  210  corresponding to the first frequency F 1  MHz of the first source  110 , the second sub matcher  220  corresponding to the second frequency F 2  MHz of the second source  120 , the third sub matcher  230  corresponding to the third frequency F 3  MHz of the third source  130 , and/or the fourth sub matcher  240  corresponding to the fourth frequency F 4  MHz of the fourth source  140 . Each of the first, second, third, and fourth sub matchers  210 ,  220 ,  230 , and  240  may adjust impedance so that RF power having a corresponding frequency may be maximally delivered. As described above, when the number of sources is changed, the number of sub matchers of the matcher  200  may also be changed. 
     The controller  300  may control a signal applied from each of the first RF power source  100   a  and the second RF power source  100   b.  In addition, the controller  300  may control intensities, start time points, and the like of currents applied to the first and second coils  551  and  552 . In other words, the controller  300  may temporally and/or spatially control plasma inside the plasma chamber  500 . Also, the controller  300  may control the signal applied from each of the first RF power source  100   a  (e.g., the first RF current) and the second RF power source  100   b  (e.g., the second RF current), according to a composition ratio of a process gas in the first area A 1 . 
     The controller  300  may be implemented by hardware, firmware, software, or any combination thereof. For example, the controller  300  may be a computing apparatus such as a workstation computer, a desktop computer, a laptop computer, or a tablet computer. For example, the controller  300  may include a memory device, such as read only memory (ROM) or random access memory (RAM), and a processor configured to perform certain operations and algorithms, for example, a microprocessor, a central processing unit (CPU), or a graphics processing unit (GPU), and the like. In addition, the controller  300  may include a receiver and a transmitter for receiving and transmitting an electrical signal. 
     The controller  300  may control and adjust a distribution of plasma inside the plasma chamber  500  by selectively and/or independently controlling very high frequencies (VHFs) from among frequencies of RF power. For example, the controller  300  may control and adjust the distribution of plasma inside the plasma chamber  500  by selectively and/or independently controlling harmonics of the first and fourth frequencies F 1  MHz and F 4  MHz of the first and fourth sources  110  and  140  corresponding to VHFs. Here, the distribution of plasma may refer to a density distribution of plasma. 
     The controller  300  may not affect the matcher  200  and the transmission line  400 . In other words, in the plasma processing apparatus  1000  of the example embodiment, addition of the controller  300  may not affect delivery characteristics of pieces of RF power by the matcher  200  and the transmission line  400 . When the delivery characteristics of the pieces of RF power by the matcher  200  and the transmission line  400  are changed by the addition of the controller  300 , the matcher  200  and the transmission line  400  need to be redesigned for maximum RF power delivery. 
     In the plasma processing apparatus  1000  of the example embodiment, the controller  300  may effectively control and adjust the distribution of plasma inside the plasma chamber  500  without affecting RF power delivery characteristics. 
     The transmission line  400  may be arranged between the matcher  200  and the plasma chamber  500  to deliver pieces of RF power to the plasma chamber  500 . In the example embodiment, the controller  300  is arranged as an output terminal of the matcher  200 , and thus, the transmission line  400  may be regarded as arranged between the controller  300  and the plasma chamber  500 . The transmission line  400  may be arranged also between the RF power source  100  and the matcher  200 . The transmission line  400  may include, for example, a conductive material such as copper. 
     The transmission line  400  may be implemented as, for example, a coaxial cable, an RF strap, an RF rod, or the like. The coaxial cable may include a central conductor, an outer conductor, an insulator, and a sheath. The coaxial cable may have a structure in which the central conductor and the outer conductor are coaxially arranged. In general, the coaxial cable may generate less attenuation even at a high frequency, and thus may be appropriate for broadband transmission, and also, may generate less leakage due to the presence of the outer conductor. Accordingly, the coaxial cable may be mainly used as a transmission cable used when a frequency is high. For example, the coaxial cable may effectively deliver RF power having a frequency in the range of several MHz to several tens of MHz without leakage. The coaxial cable includes two types of coaxial cables having characteristic impedance of 50Ω and 75Ω, respectively. 
     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 a circular tube shape enclosing the strap conductor at a certain distance. The ground housing may protect the strap conductor from RF radiation. The insulator may fill a space between the strap conductor and the ground housing. The RF rod may be structurally different from the RF strap in terms of including a rod conductor instead of the strap conductor. In detail, the rod conductor of the RF rod may have a cylindrical shape extending in one direction. The RF strap or the RF rod may deliver, for example, RF power having a frequency in the range of several MHz to several tens of MHz. 
     Impedance characteristics of the transmission line  400  may be changed via changes in physical characteristics of the implemented coaxial cable, RF strap, RF rod, and the like. For example, when the transmission line  400  is implemented as the coaxial cable, the impedance characteristics of the transmission line  400  may be changed by changing a length of the coaxial cable. Also, when the transmission line  400  is implemented as the RF strap or the RF rod, the impedance characteristics of the transmission line  400  may be changed by changing a length of the strap conductor or the rod conductor, changing a space size of the ground housing, or changing a dielectric constant and/or permeability of the insulator. 
     The transmission line  400  may include a first transmission line  410  and a second transmission line  420 . The first transmission line  410  may be connected to the first, second, and third sources  110 ,  120 , and  130  to be connected to the electrostatic chuck  530  inside the plasma chamber  500 . In addition, the second transmission line  420  may be connected to the fourth source  140  to be connected to the first and second coils  551  and  552  inside the plasma chamber  500 . According to another example embodiment, the second transmission line  420  may be connected to the fourth source  140  to be connected to the conductor plate ( 590  of  FIG.  4   ) inside the plasma chamber  500 . However, the embodiment is an example, and apparatuses connected to the first and second transmission lines  410  and  420  may be variously modified. Also, as described above, the number of sources connected to each transmission line  400  may be variously modified. 
     The plasma chamber  500  may be divided into the first area A 1  and the second area A 2 . Also, the plasma chamber  500  may include the chamber body  510 , the electrostatic chuck  530 , the first and second coils  551  and  552 , and a distribution plate  570 . The distribution plate  570  may include an ion filter and a gas hole. The first area A 1  may be located in a lower portion of the chamber body  510 , and the electrostatic chuck  530  may be arranged in the first area A 1 . The second area A 2  may be located in an upper portion of the chamber body  510 , and the first and second coils  551  and  552  may be arranged in the second area A 2 . The first area A 1  and the second area A 2  may be partitioned by the distribution plate  570 . 
     The plasma chamber  500  may be a chamber for a plasma process, and plasma may be generated therein. The plasma chamber  500  may be a CCP chamber, an ICP chamber, or a CCP and ICP combined chamber. However, the plasma chamber  500  is not limited to the chambers stated above. For reference, according to a type of a plasma chamber and a type of RF power applied to the plasma chamber, a plasma processing apparatus may be classified into a CCP type, an ICP type, and a CCP and ICP combined type. The plasma processing apparatus  1000  of the example embodiment may include a CCP type or an ICP type. Also, the plasma processing apparatus  1000  of the example embodiment may be implemented as a CCP and ICP combined type. 
     The chamber body  510  may define a reaction space in which plasma is formed, and seal the reaction space from the outside. The chamber body  510  may be normally formed of a metal material, and may maintain a ground state to block noise from the outside during the plasma process. The chamber body  510  may have a gas inlet, a gas outlet, a view-port, and the like formed thereat. A process gas needed for the plasma process may be supplied via the gas inlet. Here, the process gas may refer to all gases needed in a plasma process, such as a source gas, a reaction gas, and a purge gas. After the plasma process, gases inside the plasma chamber  500  may be exhausted to the outside through the gas outlet. In addition, pressure inside the plasma chamber  500  may be adjusted via the gas outlet. One or more view-ports may be formed in the chamber body  510 , and the inside of the plasma chamber  500  may be monitored via the view-ports. 
     Also, a gas supply  522  supplying the process gas may be connected above the second area A 2  of the plasma chamber  500  via a gas pipe  524 . The gas supply  522  and the gas pipe  524  may be referred to as a gas supply unit  520 . The gas pipe  524  may inject, into the plasma chamber  500 , process gases supplied through a plurality of injection holes. When the gas supply  522  distributes a process gas into the plasma chamber  500 , the gas pipe  524  may perform spatial control of the process gas. For example, the gas pipe  524  may inject the process gas into respective spaces of the plasma chamber  500  at different concentrations. 
     The electrostatic chuck  530  may be arranged in a lower portion of the first area A 1  of the plasma chamber  500 . The wafer  2000  to be subjected to the plasma process may be arranged and fixed on an upper surface of the electrostatic chuck  530 . The electrostatic chuck  530  may fix the wafer  2000  by an electrostatic force. In addition, the electrostatic chuck  530  may include a bottom electrode for the plasma process. The electrostatic chuck  530  may be connected to the RF power source  100  via the first transmission line  410 . In particular, the electrostatic chuck  530  may be connected to the first, second, and third sources  110 ,  120 ,  130  via the first transmission line  410 . In other words, the electrostatic chuck  530  may be connected to the first RF power source  100   a.  Accordingly, pieces of RF power from the RF power source  100  may be applied into the plasma chamber  500  via the electrostatic chuck  530 . 
     The first coil  551  and the second coil  552  may be arranged in an upper portion of the second area A 2  of the plasma chamber  500 . The first coil  551  and the second coil  552  may be connected to the RF power source  100 , such that generation of plasma may be spatially controlled inside the plasma chamber  500 . The first coil  551  and the second coil  552  may be connected to the RF power source  100  via the second transmission line  420 . In particular, the first coil  551  and the second coil  552  may be connected to the fourth source  140  via the second transmission line  420 . In other words, the first coil  551  and the second coil  552  may be connected to the second RF power source  100   b.  Accordingly, RF power from the RF power source  100  may be applied into the plasma chamber  500  via the first coil  551  and the second coil  552 . 
     From a planar viewpoint, the first coil  551  may surround a side of the second coil  552 . In other words, the first coil  551  may be positioned in a same plane as the second coil  552  and may surround the second coil  552 . When an intensity of a current applied to the first coil  551  and an intensity of a current applied to the second coil  552  are different from each other, generation of plasma may be spatially controlled in the second area A 2 . For example, a ratio of the intensity of the current applied to the second coil  552  to the intensity of the current applied to the first coil  551  may be about 10% to about 1000%. 
     The distribution plate  570  may be arranged between the first area A 1  and the second area A 2  of the plasma chamber  500 . The ion filter and the gas hole of the distribution plate  570  may pass plasma generated in the second area A 2  to the first area A 1 . The plasma generated in the second area A 2  may be filtered through the ion filter and the gas hole of the distribution plate  570  and move to the first area A 1 . The distribution plate  570  may include a top electrode. For example, the distribution plate  570  may be connected to ground in the plasma process. 
     The plasma processing apparatus  1000  may include at least one RF sensor. The RF sensor may be arranged at an output terminal of the RF power source  100 , or an input terminal or an output terminal of the matcher  200 , or the like to measure RF power delivered to the plasma chamber  500  and/or impedance of the plasma chamber  500 . The delivery of the RF power to the plasma chamber  500  may be effectively managed and adjusted by monitoring a state of the plasma chamber  500  via the RF sensor, and accordingly, the plasma process may be performed precisely. 
     Although etching is mainly described above, the plasma processing apparatus  1000  of the example embodiment may be equipment for a deposition process or a cleaning process. Accordingly, the plasma processing apparatus  1000  of the example embodiment may uniformly perform deposition or cleaning on the wafer  2000  to be subjected to the plasma process by making a distribution of plasma uniform. Hereinafter, even when not mentioned in detail, the plasma processing apparatus  1000  may be used not only for an etching process but also for a deposition process or a cleaning process. 
     A normal plasma processing apparatus employing direct plasma technology for directly generating plasma inside a plasma chamber lacks temporal and/or spatial control over generation of plasma. Therefore, plasma is generated regardless of a progress state of processes on a wafer arranged in the plasma processing apparatus, and thus, a plasma process for the wafer is not effectively performed. 
     However, the plasma processing apparatus  1000  of the example embodiment may include the first and second coils  551  and  552 , and/or the conductor plate  590  of  FIG.  4    to provide a spatial control method for generation of plasma and/or control of plasma. Also, the plasma processing apparatus  1000  may provide temporal and/or spatial control methods for generation of plasma and/or control of plasma by changing a period of each of a signal applied from the first RF power source  100   a  (e.g., a first RF current), a signal applied to the first coil  551  (e.g., a first coil current), and/or a signal applied to the second coil  552  (e.g., a second coil current), and/or controlling a start time point thereof. In other words, the plasma processing apparatus  1000  of the example embodiment may temporally and/or spatially control plasma according to a progress state of processes on the wafer  2000 . Therefore, the efficiency of a semiconductor process may be increased. 
     The relationship between the intensity of the current applied to the first coil  551  and the intensity of the current applied to the second coil  552 , and the start time point of each of the signal applied from the first RF power source  100   a  and the signal applied to each of the first and second coils  551  and  552  will be described in detail with reference to  FIGS.  2 A through  2 D . 
       FIG.  1 A  illustrates that the second area A 2 , in which the first and second coils  551  and  552  are arranged, is above the first area A 1 , in which the electrostatic chuck  530  is arranged, but the positional relationship between the first area A 1  and the second area A 2  is not limited thereto. For example, the first area A 1  may be arranged to the right or left of the second area A 2 , and/or above the second area A 2 . However, when the first and second coils  551  and  552  are arranged in the second area A 2 , the first area A 1  may not be arranged above the second area A 2 . In other words, the second area A 2  including the first and second coils  551  and  552  of the example embodiment may be arranged below the first area A 1 , or to the right and/or left of the first area A 1 . 
       FIGS.  2 A to  2 D  are graphs illustrating an intensity of a signal applied to the first coil  551 , an intensity of a signal applied to the second coil  552 , and an intensity of a signal applied from the first RF power source  100   a,  according to example embodiments. The same description of  FIGS.  2 A to  2 D  as that of  FIGS.  1 A and  1 B  will be briefly given or will be omitted. 
     Referring to  FIGS.  1 A to  2 D  together, an intensity of a signal applied to the first coil  551 , an intensity of a signal applied to the second coil  552 , and an intensity of a signal applied from the first RF power source  100   a  may be controlled according to a waveform of a periodic function.  FIGS.  2 A to  2 D  illustrate that the periodic function is applied in the form of a rectangular function, but the form of the periodic function is not limited thereto. For example, the periodic function may have the form of a trigonometric function. Temporal control of plasma inside the plasma chamber  500  will now be described in detail. 
     A first period T 1  may include a first duty D 1  and a second duty D 2 . During the first duty D 1 , source power applied to the plasma chamber  500  may be first power P 1 . During the second duty D 2 , source power applied to the plasma chamber  500  may be second power P 2 . The first power P 1  may be greater than the second power P 2 . 
     In an example, the second power P 2  may be off power (i.e., 0), and, in this case, the first duty D 1  may be an on duty, and the second duty D 2  may be an off duty. In an example, each of the first power P 1  and second power P 2  may be greater than 0. 
     Referring to  FIG.  2 A , the intensity of the current applied to the first coil  551  may be about twice the intensity of the current applied to the second coil  552 . As described above, the intensity of the current applied to the first coil  551  may range from about 0.1 times to about 10 times the intensity of the current applied to the second coil  552 . Also, the signal applied to the first coil  551 , the signal applied to the second coil  552 , and the signal applied from the first RF power source  100   a  may each have the same start time point. In addition, as shown in  FIG.  2 A , each of the signal applied to the first coil  551 , the signal applied to the second coil  552 , and the signal applied from the first RF power source  100   a  may be repeatedly changed with the period of repetition being the first period T 1 . 
     In  FIG.  2 A , each of the signal applied to the first coil  551 , the signal applied to the second coil  552 , and the signal applied from the first RF power source  100   a  may be controlled in an on/off form in which the first duty D 1  is an on duty and the second duty D 2  is an off duty. 
     According to an embodiment, a range of the first duty D 1  may be about 0.05 ms to about 5 ms. According to example embodiments, the second duty D 2  may be shorter than the first duty D 1 . 
     Referring to  FIG.  2 B , the intensity of the current applied to the first coil  551  may be about 0.5 times the intensity of the current applied to the second coil  552 . Also, each of the signal applied to the first coil  551 , the signal applied to the second coil  552 , and the signal applied from the first RF power source  100   a  may be controlled in an on/off form in which the first duty D 1  is an on duty and the second duty D 2  is an off duty. 
     Referring to  FIG.  2 C , the signal applied to the first coil  551 , the signal applied to the second coil  552 , and the signal applied from the first RF power source  100   a  may have different start time points. A difference among the start time points of the signal applied to the first coil  551 , the signal applied to the second coil  552 , and the signal applied from the first RF power source  100   a,  i.e., a range of a second period T 2  as shown in  FIG.  2 C , may be about 1 ms to about 100 ms. The second period T 2  may be variously modified according to the first period T 1 , a type of a process gas, and/or a type of plasma. Also, each of the signal applied to the first coil  551 , the signal applied to the second coil  552 , and the signal applied from the first RF power source  100   a  may be controlled in an on/off form in which the first duty D 1  is an on duty and the second duty D 2  is an off duty. 
     As shown in  FIG.  2 C , the start time point of the signal applied from the first RF power source  100   a  may be earlier than a start time point of a signal applied from the second RF power source  100   b.  Also, the start time point of the signal applied from the first RF power source  100   a  may be later than the start time point of the signal applied from the second RF power source  100   b.    
     Referring to  FIG.  2 D , each of the signal applied to the first coil  551 , the signal applied to the second coil  552 , and the signal applied from the first RF power source  100   a  may be repeatedly changed with a third period T 3 . The third period T 3  may include a third duty D 3  and a fourth duty D 4 . During the third duty D 3 , source power applied to the plasma chamber  500  may be third power P 3 . During the fourth duty D 4 , source power applied to the plasma chamber  500  may be fourth power P 4 . The third power P 3  may be greater than the fourth power P 4 . Both the third power P 3  and the fourth power P 4  may be greater than 0, and may be controlled in a high/low form in which the third power P 3  is greater than the fourth power P 4 . In other words, a signal of each of first power and second power may maintain an on duty during a time for which plasma is generated. 
       FIGS.  3 A and  3 B  are graphs illustrating distributions of a process gas in a space inside the plasma chamber  500 , according to an embodiment. The same description of  FIGS.  3 A and  3 B  as that of  FIGS.  1 A to  2 D  will be briefly given or omitted. Also, temporal control of plasma inside the plasma chamber  500  will be described in detail. 
     Referring to  FIGS.  1 A to  3 B  together, distributions of a process gas along first and second directions (e.g., X and Y directions as shown in  FIG.  1 A ) may be different from each other. Graph lines (a) to (c) of  FIG.  3 A  illustrate concentrations of different components of the process gas in a first horizontal direction (an X direction), and graph lines (d) to (f) of  FIG.  3 B  illustrate concentrations of different components of the process gas in a second horizontal direction (a Y direction). For example, a first composition ratio of different components (a) to (c) of the process gas at a first horizontal position in the X direction is different from a second composition ratio of the different components (a) to (c) of the process gas at a second horizontal position in the X direction. For example, a first composition ratio of different components (d) to (f) of the process gas at a first horizontal position in the Y direction is different from a second composition ratio of the different components (d) to (f) of the process gas at a second horizontal position in the Y direction. 
     Graph lines (a) to (f) of  FIGS.  3 A and  3 B  are examples, and the distributions of the process gas along a horizontal direction are not limited thereto. A distribution of a process gas injected in a horizontal space from the gas pipe  524  may be changed via spatial control of the process gas. For example, according to a distribution of plasma in the first area A 1 , the gas pipe  524  may be controlled, and thus, a distribution of a process gas in a horizontal space may be changed. 
     In more detail, a plasma sensor measuring a distribution of plasma may be arranged inside the plasma chamber  500 . On the basis of a measured value by the plasma sensor, the controller  300  may spatially and/or temporally control plasma inside the plasma chamber  500 . 
     According to an embodiment, for spatial control of plasma inside the plasma chamber  500 , the controller  300  may control the gas pipe  524  or may control relative intensities of currents applied to the first and second coils  551  and  552 . 
       FIG.  4    is a block diagram of a plasma processing apparatus  1000   a  according to an example embodiment. The same description of  FIG.  4    as that of  FIGS.  1 A to  3 B  will be briefly given or omitted. 
     Referring to  FIG.  4   , the plasma processing apparatus  1000   a  of the example embodiment may be different from the plasma processing apparatus  1000  of  FIG.  1 A  in terms of having a structure in which a fourth source  140  is applied to a plasma chamber  500   a  via the conductor plate  590  of the plasma chamber  500   a.  The conductor plate  590  may be arranged in a second area A 2  of the plasma chamber  500   a.  In detail, in the plasma processing apparatus  1000   a  of the example embodiment, the conductor plate  590  of the plasma chamber  500   a  may include a top electrode, and a second RF power source  100   b  may be connected to the conductor plate  590 . Accordingly, pieces of RF power from an RF power source  100  may be applied to the plasma chamber  500   a  via a matcher  200 , a controller  300 , a second transmission line  420 , and the conductor plate  590 . 
     In other words, the plasma processing apparatus  1000   a  may have a structure in which pieces of RF power may be applied to both an electrostatic chuck  530  and the conductor plate  590 . In such a structure, the RF power source  100 , the matcher  200 , and the controller  300  may be connected to each of the electrostatic chuck  530  and the conductor plate  590 . In addition, when a plasma process is performed via the plasma processing apparatus  1000   a  having such a structure, pieces of RF power may be applied via either the electrostatic chuck  530  or the conductor plate  590 . Also, according to embodiments, pieces of RF power may be alternately applied to the electrostatic chuck  530  and the conductor plate  590 . 
     As described above, for example, first, second, and third sources  110 ,  120 , and  130  may be connected to the electrostatic chuck  530  via a first transmission line  410 , and the fourth source  140  may be connected to the conductor plate  590  via a second transmission line  420 .  FIG.  4    illustrates that the second area A 2  is arranged above a first area A 1 , but the positional relationship between the first area A 1  and the second area A 2  is not limited thereto. For example, the first area A 1  may be arranged above the second area A 2 , or to the right and/or left of the second area A 2 . 
       FIG.  5    is a block diagram of a plasma processing apparatus  1000   b  according to an example embodiment. 
     Referring to  FIG.  5   , when a structure of an electrostatic chuck  530  inside a plasma chamber  500  is described in more detail, the electrostatic chuck  530  may include an electrode portion  532 , an insulating isolation  534 , an edge ring  536 , and a conductive ring  538 . The electrode portion  532  may be arranged at a central portion of a first area A 1  of the plasma chamber  500 , and include an electrode for applying power for chucking/de-chucking and plasma processes, and the like for a wafer  2000 . The wafer  2000  to be subjected to the plasma process may be arranged on an upper surface of the electrode portion  532  and fixed by an electrostatic force. 
     The insulating isolation  534  may have a structure surrounding the electrode portion  532 , and the insulating isolation  534  may be formed of, for example, an insulator such as alumina. However, the material of the insulating isolation  534  is not limited thereto. 
     The edge ring  536  may have a structure surrounding the wafer  2000  and may be arranged outside the electrode portion  532 . The edge ring  536  may be formed of silicon, and prevent plasma from concentrating on an edge portion of the wafer  2000  by inducing an effect of extending a silicon region of the wafer  2000 . The edge ring  536  may include one ring type and two ring types, and the one ring type may be referred to as a focus ring, and the two ring types may be referred to as a combo-ring. 
     The conductive ring  538  may be arranged inside the insulating isolation  534  to surround the electrode portion  532 . The conductive ring  538  may be formed of metal, such as aluminum. However, the material of the conductive ring  538  is not limited thereto. The conductive ring  538  may be electrically coupled to the edge ring  536  arranged above, and contribute to adjustment of a distribution of plasma by the edge ring  536 . 
     For reference, the structure of the electrostatic chuck  530  inside the plasma chamber  500  of the plasma processing apparatuses  1000  and  1000   a  of  FIGS.  1 A and  4    may be substantially the same as that of the electrostatic chuck  530  of the plasma processing apparatus  1000   b  of the embodiment, but is simply illustrated for convenience. 
       FIG.  6    is a flowchart illustrating a method of manufacturing a semiconductor device, according to an example embodiment. 
     Referring to  FIGS.  1 A to  2 D and  6    together, in P 100 , the wafer  2000  may be loaded onto the electrostatic chuck  530  arranged in the first area A 1  of the plasma chamber  500 . In P 200 , a process gas may be injected into the plasma chamber  500 . In a process of injecting the process gas, a concentration of the process gas may be spatially controlled, such that plasma may be spatially controlled. 
     In P 300 , plasma may be generated by supplying second RF power to the second area A 2  of the plasma chamber  500 . The second RF power may be delivered to the first coil  551  and/or the second coil  552 . The controller  300  may spatially control plasma by controlling intensities of currents applied to the first coil  551  and/or the second coil  552 . In P 300 , the second RF power may be spatially controlled. The spatial control of the second RF power may be substantially the same as that described with reference to  FIG.  1 A . 
     In P 400 , the wafer  2000  may be processed by supplying pieces of first RF power to the first area A 1  of the plasma chamber  500 . The processing may be a deposition process of depositing a thin film, for example, an oxide film or a nitride film on the wafer  2000 . Wafer processing may be an etching process of etching a material film formed on the wafer  2000 , for example, an oxide film or a nitride film. In P 400 , the first RF power and the second RF power may be controlled temporally. The temporal control of the first RF power and the second RF power may be substantially the same as that described with reference to  FIGS.  2 A to  2 D . In other words, a signal of each of the first and/or second RF power may be repetitive, and may be controlled in an on/off form or in a high/low form. Also, the signals of the first RF power and the second RF power may have the same or different periods. In addition, the signals of the first RF power and the second RF power may have the same or different start time points. 
     In P 500 , a semiconductor device may be manufactured by unloading the wafer  2000  from the electrostatic chuck  530 . 
     While the disclosure has been particularly shown and described with reference to example embodiments thereof, 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.