Patent Publication Number: US-2022223403-A1

Title: Deposition method and plasma processing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is based upon and claims priority to Japanese Patent Application No. 2021-002978, filed on Jan. 12, 2021, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a deposition method and a plasma processing apparatus. 
     2. Background Art 
     A deposition method is known in which a thin film made of an impurity-containing silicon nitride film is formed on the surface of a wafer by supplying a silane-based gas, a nitride gas, and an impurity-containing gas into a process container (see, for example, Patent Document 1). In this deposition method, the silane-based gas and the nitride gas are alternately supplied, the impurity-containing gas is simultaneously supplied with a silicon-based gas, and the nitride gas is activated by plasma. 
     PRIOR ART DOCUMENT 
     Patent Document 
     [Patent Document 1] Japanese Laid-open Patent Publication No. 2006-270016 
     The present disclosure provides a technique that enables to deposit a high-quality film at a low temperature and a high cycle rate. 
     SUMMARY 
     According to one aspect of the present disclosure, a deposition method of depositing a silicon nitride film on a surface of a substrate includes: (a) exposing the substrate to a plasma formed from a nitriding gas containing nitrogen (N) and hydrogen (H); (b) exposing the substrate to a plasma formed from hydrogen (H 2 ) gas; (c) exposing the substrate to a plasma formed from a process gas containing a halogen; (d) supplying trisilylamine (TSA) to the substrate; and (e) repeating (a) to (d) in this order. 
     According to the present disclosure, a high-quality film can be deposited at a low temperature and a high cycle rate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating a relationship between a deposition temperature of a SiN film and a cycle rate; 
         FIG. 2  is a diagram illustrating a relationship between the deposition temperature of the SiN film and a WER; 
         FIG. 3  is a schematic longitudinal cross-sectional view illustrating an example of a plasma processing apparatus according to an embodiment; 
         FIG. 4  is a schematic lateral cross-sectional view illustrating an example of the plasma processing apparatus according to the embodiment; 
         FIG. 5  is a flowchart illustrating an example of a deposition method according to the embodiment; 
         FIG. 6  is a timing chart illustrating an example of the deposition method according to the embodiment; 
         FIG. 7  is a diagram illustrating an initial state of a reaction of TSA to an NH 2  surface; 
         FIG. 8  is a diagram illustrating a first reaction path of TSA to a —NH 2  surface; 
         FIG. 9  is a diagram illustrating a second reaction path of TSA to a —NH 2  surface; 
         FIG. 10  is a diagram illustrating analysis results of physical adsorption energy and activation energy; 
         FIGS. 11A and 11B  are diagrams illustrating a surface reaction of a hydrogen radical; 
         FIG. 12  is a diagram illustrating reaction paths of TSA to a —NH surface; 
         FIG. 13  is a diagram illustrating a surface reaction of a chlorine radical; 
         FIG. 14  is a diagram illustrating a surface reaction of a chlorine radical; 
         FIGS. 15A to 15C  are diagrams each illustrating a surface reaction of a chlorine radical; 
         FIGS. 16A and 16B  are diagrams each illustrating a surface reaction of a chlorine radical; 
         FIGS. 17A to 17C  are diagrams illustrating a reaction of TSA to a chlorinated surface; 
         FIGS. 18A to 18C  are diagrams illustrating a reaction of TSA to a chlorinated surface; 
         FIGS. 19A to 19C  are diagrams comparing an activation energy of a reaction of TSA to each surface; 
         FIG. 20  is a diagram comparing an activation energy of a reaction of TSA to each surface; 
         FIGS. 21A to 21C  are diagrams comparing an energy of a final state of a reaction of TSA to each surface; and 
         FIG. 22  is a diagram comparing an energy of a final state of a reaction of TSA to each surface. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the following, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all the accompanying drawings, the same or corresponding reference numerals shall be attached to the same or corresponding members or components and overlapping descriptions may be omitted. 
     Silicon Nitride Film 
     Referring to  FIG. 1  and  FIG. 2 , a cycle rate and a wet etching rate (WER) when a silicon nitride film (SiN film) is deposited on a substrate by an atomic layer deposition (ALD) method will be described. 
     In the ALD method, a SiN film is deposited by repeating a cycle including a step of supplying a silicon (Si) raw material gas and a step of nitriding the Si raw material gas. For example, dichlorosilane (DCS), diiodosilane (DIS), triiodosilane (TIS), and trisilylamine (TSA:(SiH 3 ) 3 N) may be used as the silicon raw material gas. In the nitriding step, for example, an NH 3  plasma is used. 
     The cycle rate is a deposition amount of a SiN film per cycle in the ALD method. The WER is an etching rate when a SiN film is wet etched using a dilute hydrofluoric acid (DHF) with a fluoric acid concentration of 0.5%, and is an index for evaluating the film quality of the SiN film. For example, a lower WER means a higher quality film. 
       FIG. 1  is a diagram illustrating a relationship between the deposition temperature of the SiN film and the cycle rate. In  FIG. 1 , the horizontal axis represents the deposition temperature [° C.] and the vertical axis represents the cycle rate.  FIG. 2  is a diagram illustrating a relationship between the deposition temperature of the SiN film and the WER. In  FIG. 2 , the horizontal axis indicates the deposition temperature [° C.] and the vertical axis indicates the WER. 
     For DCS, the cycle rate is high in the temperature range of 350° C. to 650° C. as illustrated in  FIG. 1 , but the WER is high in the temperature range of 400° C. or less as illustrated in  FIG. 2 . Therefore, DCS is not suitable for depositing a high-quality film at a low temperature. 
     For DIS and TIS, the cycle rate is high in the temperature range of 200° C. to 400° C. as illustrated in  FIG. 1  and the WER is low in the temperature range of 300° C. to 400° C. as illustrated in  FIG. 2 . Therefore, it can be said that DIS and TIS are promising from the viewpoint of depositing a high-quality film at a low temperature and a high cycle rate. However, DIS and TIS have problems in reducing film thickness uniformity and handling by-products. In particular, for TIS, the vapor pressure is low and it is difficult to provide a large flow rate of gas in a short period of time. 
     For TSA, the WER is very low in the temperature range of 300° C. or less (e.g., 150° C.), as illustrated in  FIG. 2 . Therefore, it is promising from the viewpoint of depositing a high-quality film at a low temperature. However, TSA has a cycle rate lower than that of DCS, DIS and TIS as illustrated in  FIG. 1 . 
     Accordingly, as a result of having carefully studied technologies for depositing a high-quality film at a low temperature and a high cycle rate, the present inventors have found that, when TSA adsorbs to a —NH 2  surface, the silylation reaction dominates over the dehydrogenation reaction, thus the cycle rate decreases. Because the silylation reaction is a reaction in which one of three Si included in TSA adsorbs on the —NH 2  surface, the cycle rate is lower than in the dehydrogenation reaction in which all three Si included in TSA adsorb on the —NH 2  surface. 
     The present inventors also have found that upon exposing the —NH 2  surface to hydrogen and chlorine plasma before TSA is adsorbed on the —NH 2  surface, when TSA adsorbs to the —NH 2  surface, the dehydrogenation reaction dominates over the silylation reaction and the cycle rate increases. 
     In the following, a plasma processing apparatus and a deposition method according to an embodiment capable of depositing a high-quality film at a low temperature and a high cycle rate will be described. 
     Plasma Processing Apparatus 
     Referring to  FIG. 3  and  FIG. 4 , an example of a plasma processing apparatus according to an embodiment will be described. 
     The plasma processing apparatus  100  includes a process container  1  having a cylindrical shape with a ceiling and an opened lower end. The entire process container  1  may be made of, for example, quartz. A ceiling plate  2  formed of quartz is provided near the upper end of the process container  1  inside the process container  1 , and the region below the ceiling plate  2  is sealed. A manifold  3  formed of a metal in a cylindrical shape is coupled to the opening at the lower end of the process container  1  via a seal member  4  such as an O-ring. 
     The manifold  3  supports the lower end of the process container  1 , and a wafer boat  5  is inserted into the process container  1  from the lower portion of the manifold  3 . In the wafer boat  5 , a large number of (e.g., 25 to 150) substrates W are arranged in multiple stages. In this way, a large number of wafers W are accommodated substantially horizontally at intervals along the vertical direction in the process container  1 . The wafer boat  5  may be made of, for example, quartz. The wafer boat  5  has three rods  6  (see  FIG. 2 ), and a large number of wafers W are supported by grooves (not illustrated) formed in the rods  6 . The substrates W may be, for example, semiconductor wafers. 
     The wafer boat  5  is placed on a table  8  via a heat reserving cylinder  7  made of quartz. The table  8  is supported on a rotary shaft  10  that penetrates a lid  9  made of a metal (stainless steel) and configured to open and close the opening of the lower end of the manifold  3 . 
     A magnetic fluid seal  11  is provided at the penetrating portion of the rotary shaft  10 , and airtightly seals and rotatably supports the rotary shaft  10 . A seal member  12  is provided between the peripheral portion of the lid  9  and the lower end of the manifold  3  to maintain the airtightness inside the process container  1 . 
     The rotary shaft  10  is attached to the tip of an arm  13  supported by a lifting and lowering mechanism (not illustrated) such as a boat elevator, and the wafer boat  5  and the lid  9  are integrally lifted and lowered and inserted into and removed from the process container  1 . The table  8  may be provided to be fixed to the lid  9 , and the wafers W may be processed without rotating the wafer boat  5 . 
     The plasma processing apparatus  100  includes a gas supply section  20  that supplies a predetermined gas such as a process gas or a purge gas into the process container  1 . 
     The gas supply section  20  includes gas supply pipes  21  to  24 . The gas supply pipes  21  to  24  may be made of, for example, quartz. The gas supply pipes  21  to  24  penetrate the side wall of the manifold  3  inward, are bent upward, and extend vertically. A plurality of gas holes  21   a  to  23   a  are formed at predetermined intervals in the vertical portions of the gas supply pipes  21  to  23 , respectively, over the vertical length corresponding to the substrate support range of the boat  5 . Each of the gas holes  21   a  to  23   a  injects a gas in the horizontal direction. The gas supply pipe  24  is made of, for example, quartz, and includes a short quartz pipe provided to penetrate the side wall of the manifold  3 . In the illustrated example, two gas supply pipes  21 , one gas supply pipe  22 , one gas supply pipe  23 , and one gas supply pipe  24  are provided. 
     The vertical portion of each gas supply pipe  21  is provided inside the process container  1 . TSA is supplied to the gas supply pipe  21  from a raw material gas supply source through a gas pipe. The gas pipe is provided with a flow rate controller and an opening/closing valve. Accordingly, TSA from the raw material gas supply source is supplied into the process container  1  through the gas pipe and the gas supply pipe  21  at a predetermined flow rate. 
     The vertical portion of the gas supply pipe  22  is provided in a plasma generation space to be described later. Ammonia (NH 3 ) gas is supplied to the gas supply pipe  22  from an ammonia gas supply source through a gas pipe. The gas pipe is provided with a flow rate controller and an opening/closing valve. Accordingly, the NH 3  gas from the ammonia gas supply source is supplied at a predetermined flow rate to the plasma generation space through the gas pipe and the gas supply pipe  22 , is turned into plasma in the plasma generation space, and is supplied into the process container  1 . Also, hydrogen (H 2 ) gas is supplied to the gas supply pipe  22  from a hydrogen gas supply source through a gas pipe. The gas pipe is provided with a flow rate controller and an opening/closing valve. Accordingly, the H 2  gas from the hydrogen gas supply source is supplied at a predetermined flow rate to the plasma generation space through the gas pipe and the gas supply pipe  22 , is turned into plasma in the plasma generation space, and is supplied into the process container  1 . 
     The vertical portion of the gas supply pipe  23  is provided in the plasma generation space to be described later. Chlorine (Cl 2 ) gas is supplied to the gas supply pipe  23  from a chlorine gas supply source through a gas pipe. The gas pipe is provided with a flow rate controller and an opening/closing valve. Accordingly, the Cl 2  gas from the chlorine gas supply source is supplied at a predetermined flow rate to the plasma generation space through the gas pipe and the gas supply pipe  23 , is turned into plasma in the plasma generation space, and is supplied into the process container  1 . 
     The purge gas is supplied to the gas supply pipe  24  from a purge gas supply source through a gas pipe. The gas pipe is provided with a flow rate controller and an opening/closing valve. Accordingly, the purge gas from the purge gas supply source is supplied at a predetermined flow rate into the process container  1  through the gas pipe and the gas supply pipe  24 . Examples of the purge gas may include an inert gas such as argon (Ar) or nitrogen (N 2 ). The purge gas may be supplied to at least one of the gas supply pipes  21  to  23 . 
     A plasma generation mechanism  30  is formed at a portion of the side wall of the process container  1 . The plasma generation mechanism  30  turns the nitriding gas into plasma to generate an active species for nitriding. The plasma generation mechanism  30  turns the H 2  gas into plasma to generate hydrogen (H) radicals. The plasma generation mechanism  30  turns the Cl 2  gas into plasma to generate chlorine (Cl) radicals. 
     The plasma generation mechanism  30  includes a plasma partition wall  32 , a pair of plasma electrodes  33 , a power supply line  34 , a radio-frequency power source  35 , and an insulating protection cover  36 . 
     The plasma partition wall  32  is airtightly welded to the outer wall of the process container  1 . The plasma partition wall  32  may be formed of, for example, quartz. The plasma partition wall  32  has a recessed cross section, and covers an opening  31  formed in the side wall of the process container  1 . The opening  31  is formed to be elongated in the vertical direction so as to cover all of the wafers W supported by the wafer boat  5  along the vertical direction. In the inner space that is defined by the plasma partition wall  32  and that communicates with the inside of the process container  1 , that is, in the plasma generation space, the gas supply pipes  22  and  23  are arranged. The gas supply pipes  21  are located near the wafers W along the inner side wall of the process container  1  outside the plasma generation space. In the illustrated example, the two gas supply pipes  21  are arranged at positions between which the opening  31  is disposed. However, the present disclosure is not limited thereto, and for example, only one of the two gas supply pipes  21  may be disposed. 
     The pair of plasma electrodes  33  each have an elongated shape, and are arranged on the outer surfaces of both side walls of the plasma partition wall  32  along the vertical direction while facing each other. The power supply line  34  is connected to the lower end of each plasma electrode  33 . 
     The power supply line  34  electrically connects each plasma electrode  33  and the radio-frequency power source  35 . In the illustrated example, one end of the power supply line  34  is connected to the lower end of each plasma electrode  33  which is a lateral portion of the short side of the plasma electrode  33 , and the other end thereof is connected to the radio-frequency power source  35 . 
     The radio-frequency power source  35  is connected to the lower end of each plasma electrode  33  via the power supply line  34 , and supplies a radio-frequency power of, for example, 13.56 MHz to the pair of plasma electrodes  33 . As a result, the radio-frequency power is applied to the plasma generation space defined by the plasma partition wall  32 . The NH 3  gas discharged from the gas supply pipe  22  is turned into plasma in the plasma generation space to which the radio-frequency power is applied, and nitriding active species generated by the plasma are supplied into the process container  1  through the opening  31 . The H 2  gas discharged from the gas supply pipe  22  is turned into plasma in the plasma generation space to which the radio frequency power is applied, and hydrogen radicals generated by the plasma are supplied into the process container  1  through the opening  31 . Further, the Cl 2  gas discharged from the gas supply pipe  23  is turned into plasma in the plasma generation space to which the radio-frequency power is applied, and chlorine radicals generated by the plasma are supplied into the process container  1  through the opening  31 . 
     The insulating protection cover  36  is attached to the outer side of the plasma partition wall  32  so as to cover the plasma partition wall  32 . A coolant passage (not illustrated) is provided inside the insulating protection cover  36 , and a coolant such as cooled nitrogen (N 2 ) gas flows in the coolant passage so that the plasma electrodes  33  are cooled. Further, a shield (not illustrated) may be provided between the plasma electrodes  33  and the insulating protection cover  36  to cover the plasma electrodes  33 . The shield is made of, for example, a good conductor such as a metal, and is grounded. 
     An exhaust port  40  is provided in the side wall portion of the process container  1  to evacuate the inside of the process container  1 . The exhaust port  40  is formed in a vertically elongated shape corresponding to the wafer boat  5 . An exhaust port cover member  41  is attached to the portion that corresponds to the exhaust port  40  of the process container  1 , and has a U-shaped cross section to cover the exhaust port  40 . The exhaust port cover member  41  extends upward along the side wall of the process container  1 . An exhaust pipe  42  is connected to the lower portion of the exhaust port cover member  41  to exhaust the process container  1  through the exhaust port  40 . An exhaust device  44  is connected to the exhaust pipe  42 , and includes a pressure control valve  43  that controls the pressure inside the process container  1 , a vacuum pump and others. The inside of the process container  1  is exhausted by the exhaust device  44  through the exhaust pipe  42 . 
     Further, a cylindrical heating mechanism  50  is provided to surround the outer periphery of the process container  1 . The heating mechanism  50  heats the process container  1  and the wafers W inside the process container  1 . 
     The plasma processing apparatus  100  includes a controller  60 . The controller  60  performs a deposition method, which will be described below, by controlling the operation of each section of the plasma processing apparatus  100 , for example. The controller  60  may be, for example, a computer or the like. A computer program for operating each section of the plasma processing apparatus  100  is stored in a storage medium. The storage medium may be, for example, a flexible disk, a compact disk, a hard disk, a flash memory, a DVD, or the like. 
     &lt;Deposition Method&gt; 
     Referring to  FIG. 5  and  FIG. 6 , an example of a deposition method performed by the plasma processing apparatus  100  according to the embodiment will be described. 
     The deposition method according to the embodiment is a method of depositing a SiN film, and includes a nitriding step S 1 , a purge step S 2 , a hydrogen radical purge step S 3 , a purge step S 4 , a chlorine radical process step S 5 , a purge step S 6 , a TSA supply step S 7 , a purge step S 8 , and a determination step S 9 . The nitriding step S 1 , the purge step S 2 , the hydrogen radical purge step S 3 , the purge step S 4 , the chlorine radical process step S 5 , the purge step S 6 , the TSA supply step S 7 , and the purge step S 8  are repeated in this order until it is determined that a set number of times has been reached in the determination step S 9 . The deposition method according to the embodiments is performed at a low temperature, e.g., a temperature of 500° C. or less, preferably 300° C. or less. Each step will be described below. 
     In the nitriding step S 1 , the substrate W is exposed to a plasma formed from NH 3  gas. In the present embodiment, by supplying the NH 3  gas from the gas supply pipe  22  into the process container  1  and applying RF power to the pair of plasma electrodes  33  from the RF power source  35 , the NH 3  gas is converted into plasma to generate an active species for nitridation and the generated species is supplied to the substrate W. This generates —NH 2  on the surface of the substrate W. 
     In the purge step S 2 , the atmosphere in the process container  1  is replaced from NH 3  gas with N 2  gas. In the present embodiment, the atmosphere in the process container  1  is replaced from the NH 3  gas with the N 2  gas by supplying the N 2  gas from the gas supply pipe  24  into the process container  1  while exhausting the inside of the process container  1  by the exhaust device  44 . The purge step S 2  may be omitted. 
     In the hydrogen radical purge step S 3 , the substrate W is exposed to a plasma formed from H 2  gas. In the present embodiment, by supplying the H 2  gas into the process container  1  from the gas supply pipe  22  and applying RF power to the pair of plasma electrodes  33  from the RF power source  35 , the H 2  gas is converted into plasma to generate hydrogen radicals and the hydrogen radicals are supplied to the substrate W. Thereby, a hydrogen atom (H) of —NH 2  generated in the nitriding step S 1  is extracted by a hydrogen radical and an unpaired electron is generated on a nitrogen atom (N). In other words, a nitrogen atom (N) is radicalized. 
     In the purge step S 4 , the atmosphere in the process container  1  is replaced from H 2  gas with N 2  gas. In the present embodiment, the atmosphere in the process container  1  is replaced from the H 2  gas with the N 2  gas by supplying the N 2  gas from the gas supply pipe  24  into the process container  1  while evacuating the inside of the process container  1  by the exhaust device  44 . The purge step S 4  may be omitted. 
     In the chlorine radical process step S 5 , the substrate W is exposed to a plasma formed from Cl 2  gas. In the present embodiment, by supplying the Cl 2  gas from the gas supply pipe  23  into the process container  1  and applying RF power to the pair of plasma electrodes  33  from the RF power source  35 , the Cl 2  gas is converted into plasma to generate chlorine radicals and the chlorine radicals are supplied to the substrate W. This causes a chlorine radical to react with the unpaired electron on the nitrogen atom (N) generated in the hydrogen radical purge step S 3 , and the —NH 2  surface is chlorinated to generate a N—Cl bond. The N—Cl bond includes —NHCl and —NCl 2 . Thus, by changing the structure of the substrate surface from —NH 2  to —NHCl and/or —NCl 2  the activation energy of the adsorption reaction of the silyl group (—SiH 3 ) of TSA to the substrate surface decreases. 
     In the purge step S 6 , the atmosphere in the process container  1  is replaced from Cl 2  gas with N 2  gas. In the present embodiment, the atmosphere in the process container  1  is replaced from the Cl 2  gas with the N 2  gas by supplying the N 2  gas from the gas supply pipe  24  into the process container  1  while evacuating the inside of the process container  1  by the exhaust device  44 . The purge step S 6  may be omitted. 
     In the TSA supply step S 7 , TSA is supplied to the substrate W. In the present embodiment, the TSA is supplied from the gas supply pipe  21  into the process container  1 . Thereby, TSA is adsorbed on the surface chlorinated in the chlorine radical process step S 5 . At this time, because the activation energy of the adsorption reaction of the silyl group (—SiH 3 ) of TSA to the substrate surface decreases, the reaction rate of the chemical adsorption of TSA to the substrate surface increases. As a result, the adsorption amount of TSA on the substrate surface in the TSA supply step S 7  is increased. That is, the cycle rate is enhanced. 
     In the purge step S 8 , the atmosphere in the process container  1  is replaced from TSA with N 2  gas. In the present embodiment, the atmosphere in the process container  1  is replaced from TSA with the N 2  gas by supplying the N 2  gas from the gas supply pipe  24  into the process container  1  while evacuating the inside of the process container  1  by the exhaust device  44 . The purge step S 8  may be omitted. 
     In the determination step S 9 , it is determined whether or not the cycle from the nitriding step S 1  to the purge step S 8  reaches the set number of times. The set number of times is determined, for example, according to the film thickness of the SiN film to be deposited. In the determination step S 9 , when the cycle reaches the set number of times, the process ends. Thus, a SiN film having a desired thickness is deposited on the substrate W. Meanwhile, in the determination step S 9 , when the cycle does not reach the set number of times, the process returns to the nitriding step S 1 . 
     As described above, according to the deposition method according to the embodiment, by repeating the cycle of performing the nitriding step S 1 , the hydrogen radical purge step S 3 , the chlorine radical process step S 5 , and the TSA supply step S 7  in this order, the SiN film is formed on the substrate W. This exposes the —NH 2  surface to hydrogen plasma and subsequently to chlorine plasma before adsorbing TSA on the —NH 2  surface. Thus, when TSA adsorbs to the —NH 2  surface, dehydrogenation dominates over silylation, and the cycle rate increases. As a result, a high-quality film can be deposited at a low temperature and at a high cycle rate. 
     &lt;Simulation Results&gt; 
     The reaction mechanism of TSA to a —NH 2  surface was analyzed using reaction analysis software Gaussian09. In the analysis, as illustrated in  FIG. 7 , a substrate (Bulk) surface structure was SiNH 5  (H 3 Si—NH 2 ). A functional correction by the empirical dispersion model (gd3bj) was used for calculation of physical adsorption. 
       FIG. 8  is a diagram illustrating a first reaction path of TSA to a —NH 2  surface. The first reaction path is a silylation reaction in which a hydrogen atom (H) on the —NH 2  surface is replaced with SiH 3  by TSA.  FIG. 8( a )  illustrates a state in which physical adsorption due to Van der Waals force occurs between nitrogen (N2) of TSA and hydrogen (H1) on the —NH 2  surface of the substrate.  FIG. 8( b )  illustrates a transition state in which a ring structure is formed by N1-H1-N2-Si1.  FIG. 8( c )  illustrates a final state in which nitrogen (N1) on the surface is silylated to generate disilylamine (DSA:(SiH 3 ) 2 NH). E p (N—H) represents the energy of the system after physical adsorption, and E a1  represents the activation energy. 
       FIG. 9  is a diagram illustrating a second reaction path of TSA to a —NH 2  surface. The second reaction path is a dehydrogenation reaction.  FIG. 9( a )  illustrates a state in which physical adsorption due to Van der Waals force occurs between hydrogen (H3) of TSA and hydrogen (H1) on the —NH 2  surface of the substrate.  FIG. 9( b )  illustrates a transition state in which a ring structure is formed by N1-H1-H3-Si1.  FIG. 9( c )  illustrates a final state in which —SiH 2 N(SiH 3 ) 2  is bound to nitrogen (N1) on the surface and a hydrogen molecule (H 2 ) is generated. E p (H—H) represents the energy of the system after physical adsorption, and E a2  represents the activation energy. 
       FIG. 10  is a diagram illustrating the analysis results of physical adsorption energy and activation energy. It is found that both the physical adsorption energy and the activation energy of the first reaction path are smaller than those of the second reaction path and the first reaction path is the main reaction. The activation energy E a1  of the first reaction path is slightly greater than 1 eV, which is thought to determine the cycle rate. 
       FIGS. 11A and 11B  are diagrams illustrating a surface reaction of a hydrogen radical.  FIG. 11A  illustrates an analysis result of a dehydrogenation reaction of a —NH 2  surface by a hydrogen radical.  FIG. 11B  illustrates an analysis result of a dehydrogenation reaction of a —NH surface by a hydrogen radical. In  FIG. 11A  and  FIG. 11B , the initial state (IS) is illustrated on the left, and the final state (FS) is illustrated on the right. As illustrated in  FIG. 11A  and  FIG. 11B , because the activation energies are small at about 0.3 eV to 0.4 eV, a dehydrogenation reaction of a —NH 2  surface by a hydrogen radical and a dehydrogenation reaction of a —NH surface by a hydrogen radical are expected to easily occur. 
       FIG. 12  is a diagram illustrating reaction paths of TSA to a —NH surface. In  FIG. 12 , the initial state (IS) is illustrated on the left, and the transition states (TS) are illustrated on the right. As illustrated in  FIG. 12 , in a case of causing TSA to react with a surface where —NH 2  is radicalized into —NH, a dehydrogenation reaction, a H-adsorption reaction, and a silylation reaction occur. The activation energy E a3  of the dehydrogenation reaction, the activation energy E a4  of the H-adsorption reaction, and the activation energy E a5  of the silylation reaction are all small at about ˜0.1 eV. Therefore, for a reaction of TSA to the —NH surface, because the dehydrogenation reaction, the H-adsorption reaction, and the silylation reaction occur simultaneously in a mixed manner, the deposition is inefficient. 
       FIG. 13  is a diagram illustrating a surface reaction of a chlorine radical and illustrates an analysis result of a dehydrogenation reaction on a —NH 2  surface by the chlorine radical. As illustrated in  FIG. 13 , the chlorine radical physically adsorbs on the —NH 2  surface and can be stabilized at −0.76 eV. 
       FIG. 14  is a diagram illustrating a surface reaction of a chlorine radical and illustrates an analysis result of a dehydrogenation reaction on a —NHCl surface by the chlorine radical. As illustrated in  FIG. 14 , the chlorine radical physically adsorbs on the —NHCl surface and can be stabilized at −0.73 eV. 
       FIGS. 15A to 15C  are diagrams each illustrating a surface reaction of a chlorine radical and illustrating an analysis result of a radical coupling reaction.  FIG. 15A  illustrates an analysis result of an addition reaction (radical coupling reaction) of a chlorine radical to an unpaired electron on a nitrogen atom (N) on a —NH surface.  FIG. 15B  illustrates an analysis result of an addition reaction (radical coupling reaction) of a chlorine radical to an unpaired electron on a nitrogen atom (N) on a —N surface.  FIG. 15C  illustrates an analysis result of an addition reaction (radical coupling reaction) of a chlorine radical to an unpaired electron on a nitrogen atom (N) on a NCl surface. In  FIG. 15A  to  FIG. 15C , the initial state (IS) is illustrated on the left, and the final state (FS) is illustrated on the right. The activation energies of the radical coupling reactions illustrated in  FIG. 15A  to  FIG. 15C  are small at about ˜0.1 eV and therefore easily occur. Thus, it is considered that, by radicalizing the substrate surface with a hydrogen radical (generating an unpaired electron), it is possible to generate an N—Cl bond on the surface with a chlorine radical. 
       FIGS. 16A and 16B  are diagrams each illustrating a surface reaction of a chlorine radical, and illustrating an analysis result of a substitution reaction.  FIG. 16( a )  illustrates an analysis result of a substitution reaction in which a hydrogen atom on a —NH 2  surface is replaced with a chlorine atom.  FIG. 16( b )  illustrates an analysis result of a substitution reaction in which a hydrogen atom on a —NHCl surface is replaced with a chlorine atom. In  FIG. 16A  and  FIG. 16B , the initial state (IS) is illustrated on the left, and the final state (FS) is illustrated on the right. As illustrated in  FIG. 16A  and  FIG. 16B , the activation energy E a6  of the substitution reaction in which the hydrogen atom on the —NH 2  surface is replaced with the chlorine atom and the activation energy E a7  of the substitution reaction in which the hydrogen atom on the —NHCl surface is replaced with the chlorine atom are large at about 2 eV. Therefore, from the viewpoint of chlorinating the —NH 2  surface with a small activation energy, it is considered preferable to chlorinate the —NH 2  surface with a chlorine radical after radicalization with a hydrogen radical. 
       FIGS. 17A to 17C  are diagrams illustrating a reaction of TSA to a chlorinated surface and illustrating an analysis result of a reaction of TSA to a —NHCl surface.  FIG. 17A  illustrates a silylation reaction,  FIG. 17B  illustrates a dehydrogenation reaction, and  FIG. 17C  illustrates an energy diagram. In  FIG. 17A  and  FIG. 17B , the initial state (IS) is illustrated on the left, and the transition state (TS) is illustrated on the right. As illustrated in  FIG. 17C , the ratio (E a8 /E a9 ) of the activation energy E a8  of the silylation reaction to the activation energy E a9  of the dehydrogenation reaction is approximately 2.7. That is, the activation energy E a9  of the dehydrogenation reaction is less than the activation energy E a8  of the silylation reaction. Therefore, it is considered that the dehydrogenation reaction is the main reaction of the reaction of TSA to the chlorinated surface. As a result, relative to the silylation reaction to the —NH 2  surface in conventional, the deposition amount per reaction (the size of the adduct that binds to the nitrogen atom on the surface) increases. 
       FIGS. 18A to 18C  are diagrams illustrating a reaction of TSA to a chlorinated surface and illustrating an analysis result of a reaction of TSA to a —NCl 2  surface.  FIG. 18A  illustrates a silylation reaction,  FIG. 18B  illustrates a dehydrogenation reaction, and  FIG. 18C  illustrates an energy diagram. In  FIG. 18A  and  FIG. 18B , the initial state (IS) is illustrated on the left, and the transition state (TS) is illustrated on the right. As illustrated in  FIG. 18C , the ratio (E a10 /E a11 ) of the activation energy E a10  of the silylation reaction to the activation energy E a11  of the dehydrogenation reaction is approximately 1.9. Thus, the activation energy E a11  of the dehydrogenation reaction is less than the activation energy E a10  of the silylation reaction. Therefore, it is considered that the dehydrogenation reaction is the main reaction of the reaction of TSA to the chlorinated surface. 
     As a result, relative to the silylation reaction to the —NH 2  surface in conventional, the deposition amount per reaction (the size of the adduct that binds to the nitrogen atom on the surface) increases. 
       FIGS. 19A to 19C  are diagrams comparing the activation energy of a reaction of TSA to each surface.  FIG. 19A  illustrates a silylation reaction of TSA to a —NH 2  surface,  FIG. 19B  illustrates a dehydrogenation reaction of TSA to a —NHCl surface, and  FIG. 19C  illustrates a dehydrogenation reaction of TSA to a —NCl 2  surface. In  FIG. 19A  to  FIG. 19C , the initial state (IS) is illustrated on the left, and the transition state (TS) is illustrated on the right. 
       FIG. 20  is a diagram comparing the activation energy of a reaction of TSA to each surface and illustrating an analysis result of the ratio in the magnitude of the respective activation energies between the reaction of TSA to a —NH 2  surface, the reaction of TSA to a NHCl surface, and the reaction of TSA to a —NCl 2  surface. As illustrated in  FIG. 20 , the activation energies E a1 , E a9 , and E a11  of the reactions of TSA to the —NH 2  surface, the NHCl surface, and the —NCl 2  surface satisfy the relationship of E a1 &gt;E a11 &gt;E a9 . From this analysis result, it can be seen that when the —NH 2  surface is chlorinated, the activation energy of the reaction of TSA is smaller than that of the hydrogenated surface. 
       FIGS. 21A to 21C  are diagrams comparing the energy of the final state (FS) of a reaction of TSA to each surface.  FIG. 21A  illustrates a silylation reaction of TSA to a —NH 2  surface.  FIG. 21B  illustrates a dehydrogenation reaction of TSA to a —NHCl surface.  FIG. 21C  illustrates a dehydrogenation reaction of TSA to a —NCl 2  surface. In  FIG. 21A  to  FIG. 21C , the initial state (IS) is illustrated on the left, and the final state (FS) is illustrated on the right. As illustrated in  FIG. 21A , in the reaction of TSA to the —NH 2  surface, the surface is silylated in the final state (FS). In contrast, as illustrated in  FIG. 21B  and  FIG. 21C , on the chlorination surface (—NHCl surface, —NCl 2  surface) —SiH 2 NH(SiH 3 ) 2 , which is larger than the silyl group (—SiH 3 ), is bonded to the nitrogen atom (N) on the surface. Thus, the deposition amount per reaction increases. Thus, by chlorinating the NH 2  surface, the reaction path can be changed and the deposition amount per reaction can be increased. 
       FIG. 22  is a diagram comparing the energy of the final state (FS) of the reaction of TSA to each surface (the —NH 2  surface, the —NHCl surface, and the —NCl 2  surface). As illustrated in  FIG. 22 , chlorinating the —NH 2  surface makes the energy of the final state smaller than the —NH 2  surface (hydrogenated surface), thus making the product more stable. 
     It should be noted that in the above described embodiment, NH 3  gas is an example of a nitriding gas and Cl 2  gas is an example of a process gas containing a halogen. 
     The embodiment disclosed herein should be considered to be exemplary in all respects and not restrictive. The above embodiment may be omitted, substituted, or modified in various forms without departing from the appended claims and spirit thereof. 
     Although the nitriding gas is NH 3  gas in the embodiment described above, the present disclosure is not limited to this. For example, an organohydrazine compound such as diazene (N 2 H 2 ), hydrazine (N 2 H 4 ), or monomethylhydrazine (CH 3 (NH)NH 2 ) may be used as the nitriding gas. 
     Although the process gas containing a halogen is Cl 2  gas in the embodiment described above, the present disclosure is not limited to this. For example, bromine (Br 2 ) gas or iodine (I 2 ) gas may be used as the process gas containing a halogen. 
     In the above embodiment, the plasma processing apparatus has been described as a batch type apparatus that processes a plurality of substrates at once, but the present disclosure is not limited thereto. For example, the plasma processing apparatus may be a single-wafer type apparatus that processes substrates one by one. For example, the plasma processing apparatus may be a semi-batch type apparatus that revolves a plurality of substrates arranged on a rotation table in a process container by the rotation table, that causes the substrates to pass through an area to which a first gas is supplied and an area to which a second gas is supplied in order and, that processes the substrates.