Patent Publication Number: US-2023154730-A1

Title: Apparatus and method for processing substrate

Description:
This application claims the benefit of Korean Patent Application No. 10-2021-0158009, filed on Nov. 16, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a substrate processing apparatus and method. 
     2. Description of the Related Art 
     When manufacturing a semiconductor device, various processes such as etching, photography, ashing, ion implantation, thin film deposition, and cleaning are performed. 
     Here, among the etching processes, atomic layer etching (ALE) is a technology capable of controlling the etch depth of the target layer to an atomic level while minimizing electrical and physical damage. Atomic layer etching is regarded as an essential technology for making nanometer-level electronic circuits. 
     SUMMARY 
     Meanwhile, when performing atomic layer etching of aluminum oxide (Al 2 O 3 ), plasma based on a fluorine-based source (e.g., NbF 5 ) has been used. However, the fluorine-based source corrodes the inner wall/part of the process chamber or is adsorbed to the inner wall/part, and thus is not easily cleaned. 
     An object of the present invention is to provide a substrate processing method capable of stably performing atomic layer etching without damaging a process chamber. 
     Another object of the present invention is to provide a substrate processing apparatus for performing the substrate processing method. 
     The objects of the present invention are not limited to the objects mentioned above, and other objects not mentioned will be clearly understood by those skilled in the art from the following description. 
     One aspect of the substrate processing method of the present invention for achieving the above object comprises providing a substrate including a target layer in a chamber, forming a first plasma in the chamber by using a first gas containing chlorine to first reform the target layer, forming a second plasma in the chamber by using a second gas containing oxygen to second reform the first reformed target layer, providing a precursor into the chamber to react the second reformed target layer with the precursor, and removing at least a portion of the target layer by repeating forming the first plasma, forming the second plasma, and providing the precursor. 
     Another aspect of the substrate processing method of the present invention for achieving the above object comprises introducing a substrate having a semiconductor device formed thereon into a chamber, wherein the semiconductor device includes a first interlayer insulating film, a second interlayer insulating film formed on the first interlayer insulating film, a semiconductor pattern penetrating the first interlayer insulating film and the second interlayer insulating film, a charge trap film conformally formed along an upper surface of the first interlayer insulating film, a lower surface of the second interlayer insulating film, and a sidewall of the semiconductor pattern, a blocking film conformally formed along the charge trap film, and a conductive film formed to be in contact with the blocking film, wherein a portion of the blocking film is exposed by the conductive film, forming a first plasma in the chamber by using a first gas containing chlorine, forming a second plasma in the chamber by using a second gas containing oxygen, providing a precursor into the chamber to react the precursor with the blocking film exposed by the conductive film, and removing at least a portion of the blocking film exposed by the conductive film by repeating forming the first plasma, forming the second plasma, and providing the precursor. 
     One aspect of the substrate processing apparatus of the present invention for achieving the above object comprises a heat source installed in a chamber and for heating a substrate, a gas supply system for supplying a first gas, a second gas and a precursor into the chamber, an electrode system for generating plasma using the first gas or the second gas supplied into the chamber, and a controller for controlling the heat source, the gas supply system and the electrode system to atomic layer etch a target layer of the substrate, wherein the atomic layer etching comprises supplying a first gas containing chlorine into the chamber and forming a first plasma based on the first gas to first reform the target layer, supplying a second gas containing oxygen into the chamber and forming a second plasma based on the second gas to second reform the first reformed target layer, providing a precursor into the chamber to react the second reformed target layer with the precursor, and removing at least a portion of the target layer by repeating forming the first plasma, forming the second plasma, and providing the precursor. 
     The details of other embodiments are included in the detailed description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which: 
         FIG.  1    is a view for describing a substrate processing apparatus according to an embodiment of the present invention; 
         FIG.  2    is a flowchart illustrating a substrate processing method according to some embodiments of the present invention; 
         FIG.  3    is a timing diagram illustrating the substrate processing method of  FIG.  2   ; 
         FIG.  4    is a view for describing a substrate processing apparatus according to another embodiment of the present invention; 
         FIG.  5    is a view for describing a substrate processing apparatus according to another embodiment of the present invention; 
         FIGS.  6  and  7    are diagrams for describing an example, to which a substrate processing method according to some embodiments of the present invention is applied; and 
         FIG.  8    is a view for describing an experimental result using a substrate processing method according to some embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Advantages and features of the present disclosure and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments described below, but may be implemented in various different forms, and these embodiments are provided only for making the description of the present disclosure complete and fully informing those skilled in the art to which the present disclosure pertains on the scope of the present disclosure, and the present disclosure is only defined by the scope of the claims. Like reference numerals refer to like elements throughout. 
     Spatially relative terms “below,” “beneath,” “lower,” “above,” and “upper” can be used to easily describe a correlation between an element or components and other elements or components. The spatially relative terms should be understood as terms including different orientations of the device during use or operation in addition to the orientation shown in the drawings. For example, when an element shown in the figures is turned over, an element described as “below” or “beneath” another element may be placed “above” the other element. Accordingly, the exemplary term “below” may include both directions below and above. The device may also be oriented in other orientations, and thus spatially relative terms may be interpreted according to orientation. 
     Although first, second, etc. are used to describe various elements, components, and/or sections, it should be understood that these elements, components, and/or sections are not limited by these terms. These terms are only used to distinguish one element, component, or section from another element, component, or section. Accordingly, the first element, the first component, or the first section mentioned below may be the second element, the second component, or the second section within the technical spirit of the present disclosure. 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, and in the description with reference to the accompanying drawings, the same or corresponding components are given the same reference numbers, regardless of reference numerals in drawings, and an overlapped description therewith will be omitted. 
       FIG.  1    is a view for describing a substrate processing apparatus according to an embodiment of the present invention. 
     Referring to  FIG.  1   , a substrate processing apparatus  1  according to an embodiment of the present invention is an apparatus for performing atomic layer etching. The substrate processing apparatus  1  includes a chamber  100 , a heat source  150 , an electrode system  190 , a gas supply system  200 , and a controller  300 . 
     A target layer is formed on the substrate W, and at least a portion of the target layer may be etched by an atomic layer etching method, which will be described later. The target layer may include at least one of a metal oxide (e.g., aluminum oxide (Al 2 O 3 ), hafnium oxide (HfO 2 ), zirconium oxide (ZrO 2 ), silicon oxide (SiO 2 ), silicon nitride (Si 3 N 4 ), or titanium nitride (TiN). 
     The chamber  100  provides a processing space  102 , in which the substrate W is processed. For example, the chamber  100  may have a circular cylindrical shape and may be made of a metal material. Inlets  161  and  162 , through which process gases are supplied, are installed on the sidewall of the chamber  100 . An outlet  170  for discharging by-products generated in the processing space  102  to the outside is installed on the bottom surface of the chamber  100 . 
     A heat source  155  may be installed on the upper surface of the chamber  100 . The heat source  155  may be a flash lamp, an IR lamp, an RTP, a laser, a heater, or the like, but is not limited thereto. The heat source  150  adjusts the temperature of the substrate W to a temperature range suitable for atomic layer etching. For example, the heat source  150  may control the temperature of the substrate W to 50° C. or more and 400° C. or less, but is not limited thereto. The substrate support  110  is installed in the processing space  102  of the chamber  100  and the substrate W is seated on the substrate support  110 . 
     The electrode system  190  may comprise an upper electrode  191 , an RF generator  199 , a lower electrode (not shown), and the like. The RF generator  199  may comprise an RF source that generates an RF bias and a matching network that adjusts the impedance of the RF bias. An impedance-adjusted RF bias is provided to the upper electrode  191 . The lower electrode (not shown) may be embedded in the substrate support  110  and may be grounded. 
     The gas supply system  200  is configured to supply process gases through the inlets  161  and  162 . That is, the gas supply system  200  selectively provides the first gas G 1 , the second gas G 2 , and the precursor PC into the chamber  100 . Although not shown separately, the gas supply system  200  additionally provides an inert gas (e.g., Ar) into the chamber  100 . 
     The first gas storage unit  210  stores the first gas G 1 , and the first flow rate control unit  211  provides an appropriate flow rate to the chamber  100  according to the control of the controller  300 . The first flow rate control unit  211  may include a valve, a mass flow controller (MFC), and the like. The first gas G 1  is a chlorine-containing gas (i.e., a chlorine-based source), and may be, for example, at least one selected from the group comprising Cl 2 , HCl, SiCl 4 , CCl 4 , and BCl 3 . 
     The second gas storage unit  220  stores the second gas G 2 , and the second flow rate control unit  221  provides an appropriate flow rate to the chamber  100  according to the control of the controller  300 . The second gas G 2  is a gas containing oxygen (i.e., an oxygen-based source), and may be, for example, at least one selected from the group comprising O 2 , H 2 O, N 2 O, and O 3 . 
     The third gas storage unit  230  stores the precursor PC, and the third flow rate control unit  231  provides an appropriate flow rate to the chamber  100  according to the control of the controller  300 . The precursor PC may include a diketone-based gas. The precursor (PC) may be, for example, at least one selected from the group comprising Hfac (Hexafluoroacetylacetone), Acac (Acetylacetone), and Dmac (Dimethylacetamide). 
     The controller  300  is configured to control the heat source  150 , the gas supply system  200 , the electrode system  190 , and the like to atomic layer etch the target layer of the substrate W. 
     Hereinafter, an atomic layer etching method will be described in detail with reference to  FIGS.  2  and  3   .  FIG.  2    is a flowchart illustrating a substrate processing method according to some embodiments of the present invention.  FIG.  3    is a timing diagram illustrating the substrate processing method of  FIG.  2   . 
     Referring to  FIGS.  1  and  2   , hereinafter, the target layer formed on the substrate W will be described as an aluminum oxide (Al 2 O 3 ). 
     The target layer formed on the substrate W is etched by an atomic layer etching method. Atomic layer etching proceeds by continuously repeating a cycle. One cycle may proceed within 1 second (maximum 3 seconds). One cycle may proceed from nanoseconds (ns) to milliseconds (ms). One cycle includes the following steps. One cycle includes pre-processing (S 10 ) of the substrate W and thermal etching (i.e, t-ALE) (S 20 ) of the pre-processed substrate W. 
     Specifically, the pre-processing (S 10 ) includes two consecutive plasma processing (S 12  and S 14 ). 
     The substrate W is subjected to a first plasma processing using a chlorine source (S 12 ). 
     Specifically, the first gas G 1  (i.e., chlorine source) containing chlorine is supplied into the chamber  100 . The first gas G 1  may be, for example, at least one selected from the group comprising Cl 2 , HCl, SiCl 4 , CCl 4 , and BCl 3 . Hereinafter, a case, in which the first gas G 1  is Cl 2 , is exemplified. 
     A first plasma is formed based on the first gas G 1 , and the target layer (i.e., Al 2 O 3 ) is first reformed by the first plasma as shown in Chemical Formula 1 below. In Chemical Formula 1 below, the subscript (s) represents a solid. 
       Cl 2 +Al 2 O 3 ( s )→AlCl x —(Al 2 O 3 )( s )  [Chemical Formula 1]
 
     Next, the substrate W is subjected to a first plasma processing using an oxygen source (S 14 ). 
     Specifically, the second gas G 2  (i.e., an oxygen source) containing oxygen is supplied into the chamber  100 . The second gas G 2  may be, for example, at least one selected from the group comprising O 2 , H 2 O, N 2 O, and O 3 . Hereinafter, the case where the second gas G 2  is O 2  is exemplified. 
     A second plasma is formed based on the second gas G 2 , and the first reformed target layer AlCl x —(Al 2 O 3 ) is second reformed by the second plasma as shown in Chemical Formula 2 below. In Chemical Formula 2 below, the subscript (s) represents a solid. 
       O 2 +AlCl x —(Al 2 O 3 )( s )→O—AlCl 3 ( s )+(Al 2 O 3 )( s )  [Chemical Formula 2]
 
     Then, a precursor is supplied and thermal etching (t-ALE) is performed (S 20 ). 
     Specifically, the thermal etching (S 20 ) includes providing the precursor PC into the chamber  100  while maintaining the substrate W at a preset temperature (i.e., a third temperature). The precursor PC may include a diketone-based gas. The precursor PC may be, for example, at least one selected from the group comprising Hfac (Hexafluoroacetylacetone), Acac (Acetylacetone), and Dmac (Dimethylacetamide). Hereinafter, a case, in which the precursor PC is Hfac, is exemplified. 
     The second reformed target layer (O—AlCl 3 ) and the precursor PC react, and a portion of the target layer is removed as shown in Chemical Formula 3. In Chemical Formula 3 below, the subscript (s) represents a solid, and the subscript (g) represents a gas. 
       Hfac( g )+O-AlCl 3 ( s )+(Al 2 O 3 )( s )→2Al(Hfac) 3 ( g )+AlCl 3 ( g )+HCl( g )+H 2 O( g )+(Al 2 O 3 )( s )  [Chemical Formula 3]
 
     Meanwhile, during the thermal etching (S 20 ), the substrate W may be maintained at a preset temperature, that is, 50° C. or more and 400° C. or less. Within a temperature range of 50° C. or more and 400° C. or less, if the temperature is increased, the thickness of the target layer etched in one cycle may be increased. For example, when the substrate W is maintained at 150° C., 0.01 Å to 0.05 Å may be etched in one cycle. When the substrate W is maintained at 250° C., 0.1 Å to 0.25 Å may be etched in one cycle. When the substrate W is maintained at 350° C., 0.85 Å to 2 Å may be etched in one cycle. This thickness is exemplary, and may vary depending on the type, supply amount, etc. of the first gas G 1 , the second gas G 2 , and the precursor PC. 
     In addition, the set temperature of the substrate W during the thermal etching (S 20 ) may be selected differently depending on the material type of the target layer, the thickness of the target layer, the amount to be etched, the process time, and the like. That is, according to some embodiments of the present invention, the thermal etching (S 20 ) has a wide etch window from a low temperature (e.g., 50° C.) to a high temperature (e.g., 400° C.). 
     Then, it is checked whether the cycle is repeated for a preset number of times (S 30 ). If the cycle is not repeated for a preset number of times, the process returns to the pre-processing step S 10 . On the other hand, when the cycle is repeated for a preset number of times, the atomic layer etching is terminated. 
     Meanwhile, during the first plasma processing (S 12 ), the substrate W may be controlled to the first temperature, and during the second plasma processing (S 14 ), the substrate W may be controlled to the second temperature. In addition, during thermal etching (S 20 ) by supplying a precursor, the substrate W may be controlled to the third temperature. 
     The first temperature and the second temperature may be the same as each other. 
     The third temperature may be controlled to be the same as the first temperature and the second temperature. That is, during the first plasma processing (S 12 ), the second plasma processing (S 14 ), and the thermal etching (t-ALE) (S 20 ), the temperature of the substrate W may be controlled to be the same. 
     Alternatively, the first temperature and the second temperature may be controlled to be the same as each other, and the third temperature may be controlled to be higher than the first temperature and the second temperature. In order to freely control the temperature in each step (S 12 , S 14 , S 20 ), the heat source  150  may be installed on the side wall (see  FIG.  5   ) or the upper surface (see  FIG.  1   ) of the chamber  100 . 
     By using the heat source  155  using a flash lamp or the like, the temperature of the substrate W may be controlled differently for each step of the first plasma processing (S 12 ), the second plasma processing (S 14 ), and the thermal etching (t-ALE) (S 20 ). For example, in the first plasma processing (S 12 ) and the second plasma processing (S 14 ), the temperature of the substrate W may be maintained at the same temperature, and in the thermal etching (S 20 ), the temperature of the substrate W may be increased. Here, referring to  FIG.  3   , a cycle (cycle I) corresponds to times t 1  to t 7 . The first plasma processing S 12  corresponds to time t 1  to t 3 , the second plasma processing S 14  corresponds to time t 3  to t 5 , and the thermal etching S 20  corresponds to time t 5  to t 7 . 
     At times t 1  to t 2 , a first gas G 1  including chlorine is provided into the chamber  100 , and a first plasma is formed in the chamber  100 . Along with the first gas G 1 , an inert gas GC (e.g., Ar) is also provided into the chamber  100 . The inert gas GC serves as a carrier for transporting the first gas G 1 . The target layer is first reformed through the first plasma. 
     At time t 2  to t 3 , the inert gas GC continues to be provided. The inert gas GC is for exhausting by-products inside the chamber  100 . 
     At times t 3  to t 4 , the second gas G 2  including oxygen is provided into the chamber  100 , and a second plasma is formed in the chamber  100 . Along with the second gas G 2 , an inert gas GC (e.g., Ar) is also provided into the chamber  100 . The inert gas GC serves as a carrier for transporting the second gas G 2 . Through the second plasma, the first reformed target layer is second reformed. 
     At times t 4  to t 5 , the inert gas GC continues to be provided. The inert gas GC is for exhausting by-products inside the chamber  100 . 
     At time t 5  to t 6 , a precursor PC is provided into the chamber  100 . The second reformed target layer is reacted with the precursor PC. At times t 6  to t 7 , the inert gas GC continues to be provided. The inert gas GC is for exhausting by-products inside the chamber  100 . The reacted target layer (i.e., Al(hfac) 3 ) is in the form of a gas, and is exhausted to the outside together with the inert gas GC. Accordingly, the target layer is thermally etched. 
     The first cycle (cycle I) ends. 
     At times t 7  to t 8 , the second cycle (cycle II) begins. Substantially the same steps as in the first cycle (cycle I) are repeated. 
     In summary, according to the substrate processing method according to some embodiments of the present invention, the target layer (Al 2 O 3 ) may be atomic layer etched without using a fluorine-based source. That is, the target layer is atomic layer etched by pre-processing the target layer using a chlorine source and an oxygen source, and performing thermal etching by supplying a precursor. Since the fluorine-based source is not used, denaturation and corrosion of parts in the chamber  100  do not occur. 
       FIG.  4    is a view for describing a substrate processing apparatus according to another embodiment of the present invention.  FIG.  5    is a view for describing a substrate processing apparatus according to another embodiment of the present invention. For convenience of description, the points different from those described with reference to  FIGS.  1  to  3    will be mainly described. 
     Referring first to  FIG.  4   , in the substrate processing apparatus  2  according to another embodiment of the present invention, an inlet  160  for supplying process gases to the upper surface of the chamber  100  is installed. In the substrate support  110 , a heater is installed as a heat source  150 . 
     Referring to  FIG.  5   , in the substrate processing apparatus  3  according to another embodiment of the present invention, an inlet  160 , through which process gases are supplied, is installed on the upper surface of the chamber  100 . A heat source  156  is installed on the side surface of the chamber  100 . A heater may not be installed in the substrate support  110 . The heat source  156  may use a flash lamp, an IR lamp, an RTP, a laser, a heater, or the like. 
     By using the heat source  156  using a flash lamp or the like, the temperature of the substrate W may be controlled differently for each step of the first plasma processing (S 12 ), the second plasma processing (S 14 ), and the thermal etching (t-ALE) (S 20 ). For example, in the first plasma processing (S 12 ) and the second plasma processing (S 14 ), the temperature of the substrate W may be maintained at the same temperature, and in the thermal etching (S 20 ), the temperature of the substrate W may be increased. 
     In particular, the first plasma processing (S 12 ), the second plasma processing (S 14 ), and the thermal etching (t-ALE) (S 20 ) may be performed in a dual process chamber (see  100  of  FIGS.  1 ,  4  and  5   ) capable of simultaneously performing plasma processing and heat processing. 
       FIGS.  6  and  7    are diagrams for describing an example, to which a substrate processing method according to some embodiments of the present invention is applied. In  FIGS.  6  and  7   , a case, in which the substrate processing method according to some embodiments of the present invention is applied to manufacturing a vertical memory device (e.g., a three-dimensional NAND flash device), is exemplified. That is, it may be used to remove a portion of the blocking film  370  of the vertical memory device. 
     Referring to  FIG.  6   , a substrate W, on which a semiconductor device (i.e., a vertical memory device) is formed, is introduced into a chamber (see  100  of  FIG.  1   ). 
     Specifically, the vertical memory device includes a plurality of interlayer insulating films  315   a  and  315   b  stacked in one direction (i.e., vertical direction). A semiconductor pattern  420  penetrating through the plurality of interlayer insulating films  315   a  and  315   b  is included. The semiconductor pattern  420  may include single crystal silicon doped with or undoped with impurities. The semiconductor pattern  420  includes a channel region. 
     A cell formation space  99  is located between adjacent interlayer insulating films (i.e., the first interlayer insulating film  315   a  and the second interlayer insulating film  315   b ). 
     A tunneling film  390  is formed in the semiconductor pattern  420  exposed by the cell formation space  99 . The tunneling film  390  may include, for example, an oxide such as silicon oxide. 
     The charge trap film  380  may be conformally formed along the upper surface of the first interlayer insulating film  315   a , the lower surface of the second interlayer insulating film  315   b , and the tunneling film  390  (i.e., the sidewall of the semiconductor pattern  420 ). The charge trap film  380  may include, for example, a nitride such as silicon nitride. 
     The blocking film  370  is conformally formed along the charge trap film  380 . That is, the blocking film  370  includes the charge trap film  380  on the first interlayer insulating film  315   a , the charge trap film  380  in contact with the tunneling film  390 , and the charge trap film  380  under the second interlayer insulating film  315   b . The blocking film  370  may include a metal oxide (e.g., aluminum oxide (Al 2 O 3 ). 
     The conductive film  485  is formed to be in contact with the blocking film  370 . The conductive film  485  does not completely fill the cell formation space  99  but only partially fills it. Accordingly, a portion of the blocking film  370  is exposed by the conductive film  485 . 
     In particular, through holes  520  penetrating through the plurality of interlayer insulating films  315   a  and  315   b  are formed. The through hole  520  may be, for example, a hole for forming a common source line (CSL). The through hole  520  and the cell formation space  99  not filled by the conductive film  485  are connected to each other. 
     Referring to  FIG.  7   , the blocking film  370  exposed by the conductive film  485  is removed by performing atomic layer etching. 
     Specifically, the substrate W is pre-processed. That is, a first plasma is formed in the chamber  100  using a first gas G 1  containing chlorine, and a second plasma is formed in the chamber using a second gas G 2  containing oxygen. 
     Next, a precursor PC is provided into the chamber  100  to react the blocking film  370  exposed by the conductive film  485  with the precursor PC, thereby etching the blocking film  370  in units of atoms. 
     Next, the blocking film  370  exposed by the conductive film  485  is removed by repeating the above-described forming first plasma, forming second plasma, and providing the precursor PC. As a result, as shown in  FIG.  7   , one surface  485   a  of the conductive film  485  and one surface  370   a  of the blocking film  370  may be aligned with each other. One surface  485   a  of the conductive film  485  and one surface  370   a  of the blocking film  370  are exposed to the cell formation space  99 . 
     Hereinafter, with reference to  FIG.  8    and Table 1, experimental results using the substrate processing method according to some embodiments of the present invention will be described.  FIG.  8    is a view for describing an experimental result using a substrate processing method according to some embodiments of the present invention. 
     Referring to Table 1 first, the target layer includes aluminum oxide (Al 2 O 3 ). 
     While performing the first plasma processing (S 12  in  FIG.  2   ), the second plasma processing (S 14  in  FIG.  2   ), and thermal etching (S 20  in  FIG.  2   ), the substrate temperature is maintained at 200° C. 
     In relation to the first plasma processing (S 12  in  FIG.  2   ), the first gas (Cl 2 ) is supplied at 30 sccm and the inert gas (Ar) is supplied at 500 sccm into the chamber (corresponding to t 1  to t 2  in  FIG.  3   ). The first plasma is generated using the first gas (Cl 2 ). Then, the inert gas (Ar) is supplied into the chamber at 2000 sccm (corresponding to t 2  to t 3  in  FIG.  3   ) to exhaust the by-products inside the chamber. 
     With respect to the second plasma processing (S 14  in  FIG.  2   ), the second gas ( 02 ) is supplied at 30 sccm and the inert gas (Ar) is supplied at 500 sccm into the chamber (corresponding to t 3  to t 4  in  FIG.  3   ). The second plasma is generated using the second gas ( 02 ). Then, the inert gas (Ar) is supplied into the chamber at 2000 sccm (corresponding to t 4  to t 5  in  FIG.  3   ) to exhaust the by-products inside the chamber. 
     With respect to the thermal etching (S 20  in  FIG.  2   ), 25 sccm is supplied into the chamber by combining the precursor (Hfac) and the inert gas (Ar) (corresponding to t 5  to t 6  in  FIG.  3   ). Then, the inert gas (Ar) is supplied into the chamber at 2000 sccm (corresponding to t 6  to t 7  in  FIG.  3   ) to exhaust the by-products inside the chamber. 
     The above-described first plasma processing (S 12 ), second plasma processing (S 14 ), and thermal etching (S 20 ) are performed while the substrate temperature is changed to 250° C., 300° C., and 350° C. The above-described experimental conditions are summarized in [Table 1]. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                   
                   
                 Thermal etching 
               
               
                   
                 First plasma 
                 Second plasma 
                 (t-ALE) 
               
            
           
           
               
               
               
               
               
            
               
                   
                 processing 
                 processing 
                 Hfac and 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Substrate 
                 Cl 2 /Ar 
                 Ar 
                 O 2 /Ar 
                 Ar 
                 Ar 
                 Ar 
               
               
                 temperature 
                 (t1~t2) 
                 (t2~t3) 
                 (t3~t4) 
                 (t4~t5) 
                 (t5~t6) 
                 (t6~t7) 
               
               
                   
               
               
                 200° C. 
                 30/500 
                 2000 
                 30/500 
                 2000 
                 25 
                 2000 
               
               
                 250° C. 
               
               
                 300° C. 
               
               
                 350° C. 
               
               
                   
               
            
           
         
       
     
     The experimental results according to the experimental conditions of [Table 1] are shown in  FIG.  8   . 
     Referring to  FIG.  8   , the x-axis represents the substrate temperature (unit: ° C.), and the y-axis represents the amount of etching (unit: A/cycle). 
     When the substrate temperature is 200° C., the etching amount per a cycle (EPC) is 0.06 Å. When the substrate temperature is 250° C., the etching amount per a cycle is 0.18 Å. When the substrate temperature is 300° C., the etching amount per a cycle is 0.38 Å. When the substrate temperature is 350° C., the etching amount per a cycle is 0.92 Å. As the substrate temperature increases, the etching amount per a cycle increases, and as the substrate temperature decreases, the etching amount per a cycle decreases. 
     Although embodiments of the present invention have been described with reference to the above and the accompanying drawings, those skilled in the art, to which the present invention pertains, can understand that the present invention may be practiced in other specific forms without changing its technical spirit or essential features. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting.