Patent Publication Number: US-2022238345-A1

Title: Manufacturing method for semiconductor device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-012340, filed on Jan. 28, 2021, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a manufacturing method for a semiconductor device. 
     BACKGROUND 
     Along with scaling-down of a semiconductor device, it is necessary to form a recess having a high aspect ratio in a layer to be processed with high process accuracy. For example, when manufacturing a three-dimensional semiconductor memory, it is desirable to suppress the shape of the memory hole having a high aspect ratio from becoming a bowing shape. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view of a semiconductor device manufactured by a manufacturing method for a semiconductor device according to a first embodiment; 
         FIG. 2  is a schematic view of an example of a reactive ion etching device used in the manufacturing method for a semiconductor device according to the first embodiment; 
         FIGS. 3A to 3D  are schematic views showing the manufacturing method for a semiconductor device of the first embodiment; 
         FIGS. 4A to 4D  are schematic views showing the manufacturing method for a semiconductor device of the first embodiment; 
         FIGS. 5A to 5D  are schematic views showing the manufacturing method for a semiconductor device of the first embodiment; 
         FIGS. 6A to 6C  are schematic views showing the manufacturing method for a semiconductor device of the first embodiment; and 
         FIGS. 7A to 7C  are explanatory views of the function of the manufacturing method for a semiconductor device of the first embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A manufacturing method for a semiconductor device according to an embodiment includes: performing first etching for forming a recess in a layer to be processed using a reactive ion etching method; performing a first treatment of supplying a silylation agent to the recess after the performing the first etching; and performing second etching of etching a bottom surface of the recess using a reactive ion etching method after the performing the first treatment. 
     Embodiments of the present invention will be described below with reference to the drawings. In the following description, the identical or similar members are given the identical reference numerals, and description of the members once described will sometimes be omitted as appropriate. 
     In the present description, the term “up” or “down” are sometimes used for convenience. The term “up” or “down” is, for example, a term indicating a relative positional relationship in the drawings. The term “up” or “down” is not a term defining a positional relationship with respect to gravity. 
     Qualitative analysis and quantitative analysis of the chemical composition of the members constituting the semiconductor device in the present description can be carried out by, for example, secondary ion mass spectrometry (SIMS) and energy dispersive X-ray spectroscopy (EDX). In addition, for measuring the thickness of the members constituting the semiconductor device and the distance between the members, for example, a transmission electron microscope (TEM) or a scanning electron microscope (SEM). 
     The manufacturing method for a semiconductor device according to an embodiment will be described below with reference to the drawings. 
     First Embodiment 
     A manufacturing method for a semiconductor device according to a first embodiment includes: performing first etching for forming a recess in a layer to be processed using a reactive ion etching method; performing a first treatment of supplying a silylation agent to the recess after the performing the first etching; and performing second etching of etching a bottom surface of the recess using a reactive ion etching method after the performing the first treatment. 
       FIG. 1  is a schematic cross-sectional view of a semiconductor device manufactured by the manufacturing method for a semiconductor device according to the first embodiment. The semiconductor device manufactured by the manufacturing method for a semiconductor device according to the first embodiment is a nonvolatile memory  100  in which memory cells are three-dimensionally disposed.  FIG. 1  is a cross-sectional view of a memory cell array of the nonvolatile memory  100 . 
     The nonvolatile memory  100  includes a silicon substrate  10 , a channel layer  11 , a plurality of interlayer insulating layers  12 , a gate insulating layer  13 , a plurality of word lines WL, and a plurality of bit lines BL. The nonvolatile memory  100  includes a plurality of three-dimensionally disposed memory cells MC. The region enclosed by a dotted line in  FIG. 1  corresponds to one of the memory cells MC. 
     The channel layer  11  extends in the normal direction of the surface of the silicon substrate  10 . The channel layer  11  is electrically connected to the silicon substrate  10 . The channel layer  11  functions as a channel region of a transistor of the memory cell MC. The channel layer  11  is a semiconductor. The channel layer  11  is, for example, polycrystalline silicon. 
     The word lines WL are stacked in the normal direction of the surface of the silicon substrate  10 . The word line WL functions as a gate electrode of a transistor of the memory cell MC. The word line WL is, for example, a plate-like conductor. The word line WL is tungsten (W), for example. The channel layer  11  penetrates the plurality of word lines WL. 
     The interlayer insulating layer  12  is provided between the word line WL and the word line WL. The interlayer insulating layer  12  electrically separates the word line WL from the word line WL. 
     The bit line BL extends in a direction parallel to the surface of the silicon substrate  10 . The bit line BL is electrically connected to the channel layer  11 . 
     The gate insulating layer  13  is provided between the channel layer  11  and the word line WL. The gate insulating layer  13  includes, for example, a tunnel insulating film, a charge storage film, and a block insulating film that are not illustrated. The tunnel insulating film is a silicon oxide film, for example. The charge storage film is a silicon nitride film, for example. The block insulating film is an aluminum oxide film, for example. 
     The memory cell MC stores data by the charge stored in the charge storage film of the gate insulating layer  13 . The threshold voltage of the transistor of the memory cell MC varies depending on the amount of the charge stored in the charge storage film. Data stored in the memory cell MC is read by monitoring the current flowing between the word line WL and the bit line BL, which varies depending on the threshold voltage of the transistor. 
       FIG. 2  is a schematic view of an example of the reactive ion etching device used in the manufacturing method for a semiconductor device according to the first embodiment. The reactive ion etching device (RIE device) in  FIG. 2  is a two-frequency capacitively coupled plasma device (CCP device). 
     The RIE device includes, for example, a chamber  20 , a holder  22 , a first high-frequency power source  24 , a second high-frequency power source  26 , a first gas supply port  30   a , a second gas supply port  30   b , and a third gas supply port  30   c.    
     The holder  22  is provided in the chamber  20 . The holder  22  mounts a semiconductor substrate W, for example. The holder  22  is, for example, an electrostatic chuck. 
     The first high-frequency power source  24  has a function of applying high-frequency power to the chamber  20 . Plasma is generated in the chamber  20  by the first high-frequency power source  24 . The high-frequency power applied by the first high-frequency power source  24  is, for example, equal to or more than 50 W and equal to or less than 5000 W. The frequency applied by the first high-frequency power source  24  is, for example, equal to or more than 20 MHz and equal to or less than 200 MHz. 
     The second high-frequency power source  26  has a function of applying high-frequency power to the holder  22 . By applying high-frequency power to the holder  22 , the energy of ions colliding with the semiconductor substrate W is controlled. The high-frequency power applied to the holder  22  is, for example, equal to or more than 100 W and equal to or less than 10000 W. The frequency applied to the holder  22  is lower than the frequency applied to the chamber  20  by the first high-frequency power source  24 . The frequency applied to the holder  22  is, for example, equal to or more than 0.1 MHz and equal to or less than 10 MHz. 
     The semiconductor substrate W is anisotropically etched using plasma generated in the chamber  20 . 
     Next, an example of the manufacturing method of the semiconductor device according to the first embodiment will be described. 
       FIGS. 3A to 3D, 4A to 4D, 5A to 5D, and 6A to 6C  are schematic views showing the manufacturing method for a semiconductor device of the first embodiment.  FIGS. 3A to 6C  correspond to a portion including one channel layer  11  in  FIG. 1 . 
     First, a stacked body  40  is formed on the silicon substrate  10  ( FIG. 3A ). The stacked body  40  is an insulating layer. The stacked body  40  is an example of the layer to be processed. 
     The stacked body  40  includes a structure in which silicon oxide films  40   a  and silicon nitride films  40   b  are alternately stacked. The silicon oxide film  40   a  is an example of a first film. The silicon nitride film  40   b  is an example of a second film. The silicon oxide film  40   a  and the silicon nitride film  40   b  are formed by, for example, the chemical vapor deposition method (CVD method). 
     The interlayer insulating layer  12  eventually replaces a part of the silicon oxide film  40   a.    
     Next, a carbon layer  42  having a hole pattern  42   a  is formed on the stacked body  40  ( FIG. 3B ). The carbon layer  42  is an example of a mask layer. The carbon layer  42  is formed by, for example, a sputtering method. The hole pattern  42   a  is formed using, for example, the lithography method and the RIE method. 
     As the mask layer, for example, a resist layer, an insulating layer, or a metal layer can also be used. 
     Next, the silicon substrate  10  is introduced into the chamber  20  of a RIE device. In the chamber  20  of the RIE device, the first etching is performed using the carbon layer  42  as a mask. A memory hole MH is formed in the stacked body  40  by the first etching ( FIG. 3C ). The memory hole MH is an example of the recess. 
     In the first etching, the memory hole MH does not penetrate the stacked body  40 . In the first etching, the etching is stopped in the middle of the stacked body  40 . The first etching amount of the stacked body  40  in the first etching is indicated by E 1  in  FIG. 3C . 
     In the first etching, the first etching gas is supplied from the first gas supply port  30   a  into the chamber  20 , for example. The first etching is performed using the first etching gas. 
     Next, the first treatment of supplying trimethylsilyldimethylamine (TMSDMA) to the memory hole MH is performed ( FIG. 3D ). Trimethylsilyldimethylamine is an example of the silylation agent. 
     The first treatment is performed using the RIE device, for example. The first treatment is performed in the chamber  20  identical to that for the first etching, for example. For example, after the first etching is performed, the first etching and the first treatment are continuously performed without releasing the silicon substrate  10  into the atmosphere. 
     The first treatment is performed by, for example, supplying TMSDMA into the chamber  20  from the second gas supply port  30   b  of the RIE device. In the first treatment, TMSDMA is supplied as a gas to the memory hole MH. 
     By the first treatment, a protective film  44   a  is formed on a sidewall of the memory hole MH. The protective film  44   a  contains carbon. 
     Next, in the chamber  20  of the RIE device, the second etching is performed using the carbon layer  42  as a mask. At least a bottom surface of the memory hole MH is etched by the second etching ( FIG. 4A ). 
     The memory hole MH becomes further deeper than that immediately after the first etching. In the second etching, the memory hole MH does not penetrate the stacked body  40 . In the second etching, the etching is stopped in the middle of the stacked body  40 . The second etching amount of the stacked body  40  in the second etching is indicated by E 2  in  FIG. 4A . 
     For example, the first etching amount E 1  of the stacked body  40  in the first etching is larger than the second etching amount E 2  of the stacked body  40  in the second etching. The first etching amount E 1  may be equal to or smaller than the second etching amount E 2 . 
     In the second etching, the second etching gas is supplied from the first gas supply port  30   a  into the chamber  20 , for example. The second etching is performed using the second etching gas. 
     Next, a second treatment of supplying TMSDMA to the memory hole MH is performed ( FIG. 4B ). TMSDMA is an example of the silylation agent. 
     The second treatment is performed using the RIE device, for example. The second treatment is performed in the chamber  20  identical to that for the second etching, for example. For example, after the second etching is performed, the second etching and the second treatment are continuously performed without releasing the silicon substrate  10  into the atmosphere. 
     The second treatment is performed by supplying TMSDMA into the chamber  20  from the second gas supply port  30   b  of the RIE device. TMSDMA is supplied as a gas to the memory hole MH. 
     By the second treatment, a protective film  44   b  is formed on the sidewall of the memory hole MH. The protective film  44   b  contains carbon. 
     Next, in the chamber  20  of the RIE device, third etching is performed using the carbon layer  42  as a mask. At least a bottom surface of the memory hole MH is etched by the third etching ( FIG. 4C ). 
     The memory hole MH becomes further deeper than that immediately after the second etching. In the third etching, the memory hole MH does not penetrate the stacked body  40 . In the third etching, the etching is stopped in the middle of the stacked body  40 . 
     In the third etching, the third etching gas is supplied from the first gas supply port  30   a  into the chamber  20 , for example. The third etching is performed using the third etching gas. 
     Next, a third treatment of supplying TMSDMA to the memory hole MH is performed ( FIG. 4D ). TMSDMA is an example of the silylation agent. 
     The third treatment is performed using the RIE device, for example. The third treatment is performed in the chamber  20  identical to that for the third etching, for example. For example, after the third etching is performed, the third etching and the third treatment are continuously performed without releasing the silicon substrate  10  into the atmosphere. 
     The third treatment is performed by, for example, supplying TMSDMA into the chamber  20  from the second gas supply port  30   b  of the RIE device. TMSDMA is supplied as a gas to the memory hole MH. 
     By the third treatment, a protective film  44   c  is formed on the sidewall of the memory hole MH. The protective film  44   c  contains carbon. 
     Next, in the chamber  20  of the RIE device, fourth etching is performed using the carbon layer  42  as a mask. At least a bottom surface of the memory hole MH is etched by the fourth etching ( FIG. 5A ). 
     The memory hole MH becomes further deeper than that immediately after the third etching. In the fourth etching, the memory hole MH penetrates the stacked body  40  and reaches the silicon substrate  10 . 
     In the fourth etching, the fourth etching gas is supplied from the first gas supply port  30   a  into the chamber  20 , for example. The fourth etching is performed using the fourth etching gas. 
     The aspect ratio of the memory hole MH penetrating the stacked body  40  is equal to or more than  30 , for example. 
     After the fourth etching, the silicon substrate  10  is taken out from the chamber  20  of the RIE device. 
     The first etching gas, the second etching gas, the third etching gas, and the fourth etching gas contain, for example, carbon and fluorine. The first etching gas, the second etching gas, the third etching gas, and the fourth etching gas contain, for example, oxygen. The first etching gas, the second etching gas, the third etching gas, and the fourth etching gas contain, for example, hydrogen. 
     The first etching gas, the second etching gas, the third etching gas, and the fourth etching gas contain, for example, CxHyFz (x is an integer of equal to or more than 1, y is an integer of equal to or more than 0, and z is an integer of equal to or more than 1). The first etching gas, the second etching gas, the third etching gas, and the fourth etching gas contain, for example, C 4 F 6 , C 4 F 8 , and CH 2 F 2 . 
     The first etching gas, the second etching gas, the third etching gas, and the fourth etching gas contain, for example, oxygen gas. 
     The first etching gas, the second etching gas, the third etching gas, and the fourth etching gas are, for example, mixed gases of C 4 F 6 , C 4 F 8 , and CH 2 F 2 , and oxygen gas. 
     The first etching gas, the second etching gas, the third etching gas, and the fourth etching gas are, for example, the identical gas. For example, at least one of the first etching gas, the second etching gas, the third etching gas, and the fourth etching gas is different from the other gases. 
     The silylation agent is a chemical that realizes silylation. Silylation means substituting active hydrogen on the substance with a trisubstituted silyl group (—SiR 3 ). The silylation agent contains silicon. 
     The silylation agent contains, for example, carbon and hydrogen. The silylation agent contains, for example, a methyl group, an alkyl group, or a phenyl group. 
     The silylation agent contains, for example, an amino group. The silylation agent has, for example, a structure of (R 3 )—Si—N(R 2 ). The silylation agent is, for example, trimethylsilyldimethylamine (TMSDMA), bistertiarybutylaminosilane (BTBAS), bis(dimethylamino)dimethylsilane (BDMADMS), or phenyldimethylsilyldimethylamine. 
     The silylation agent contains, for example, a methoxy group. The silylation agent has, for example, a structure of R—Si—(O(Me))x. The silylation agent has, for example, a structure of CH 3 —(CH 2 )z—Si—(O—Me) 3 . The silylation agent is, for example, trimethylmethoxysilane (TMSOME), dimethylmethoxysilane (DMDMS), methyltrimethoxysilane (MTMS), or methoxydimethylphenylsilane. 
     The silylation agents used in the first treatment, the second treatment, and the third treatment are identical, for example. Moreover, in the silylation agents used in the first treatment, the second treatment, and the third treatment, for example, the silylation agent used in at least one treatment is different from the silylation agents used in the other treatments. 
     Next, the carbon layer  42 , the protective film  44   a , the protective film  44   b , and the protective film  44   c  are removed ( FIG. 5B ). The removal of the carbon layer  42 , the protective film  44   a , the protective film  44   b , and the protective film  44   c  is performed using, for example, a different device or a different condition from that for the first to fourth etching. The removal of the carbon layer  42 , the protective film  44   a , the protective film  44   b , and the protective film  44   c  is performed using, for example, a different gas from that for the first to fourth etching. The removal of the carbon layer  42 , the protective film  44   a , the protective film  44   b , and the protective film  44   c  is performed by, for example, asking treatment using oxygen plasma. 
     Next, a stacked insulating layer  46  is formed in the memory hole MH ( FIG. 5C ). The stacked insulating layer  46  has a stacked structure of a silicon oxide film, a silicon nitride film, and an aluminum oxide film, for example. The stacked insulating layer  46  eventually becomes the gate insulating layer  13 . 
     Next, a polycrystalline silicon layer  48  is formed in the memory hole MH ( FIG. 5D ). The polycrystalline silicon layer  48  eventually becomes the channel layer  11 . 
     Next, the silicon nitride film  40   b  is selectively removed ( FIG. 6A ). 
     Next, a first tungsten layer  50  is formed in the region from which the silicon nitride film  40   b  has been removed ( FIG. 6B ). The first tungsten layer  50  eventually becomes the word line WL. 
     Next, a second tungsten layer  52  is formed on the polycrystalline silicon layer  48  ( FIG. 6C ). The second tungsten layer  52  eventually becomes the bit line BL. 
     The nonvolatile memory  100  shown in  FIG. 1  is manufactured by the above manufacturing method. 
     Next, functions and effects of the semiconductor device and the manufacturing method of the semiconductor device of the first embodiment will be described. 
     In the nonvolatile memory  100  in which the memory cells are three-dimensionally disposed, in order to increase the capacity of the memory, for example, the hole diameter of the memory hole is reduced and the number of stacked word lines WL is increased. When the hole diameter of the memory hole is reduced and the number of stacked word lines WL is increased, it is necessary to form a memory hole having a high aspect ratio (depth of memory hole/hole diameter of memory hole). 
     An increase in the aspect ratio of the memory hole causes a problem that the memory hole has a bowing shape. 
     The bowing shape of the memory hole is caused by the hole diameter widening in the middle of etching for forming the memory hole. As a cause of the hole diameter widening in the middle of etching, it is conceivable that a part of the protective film formed on the sidewall of the memory hole disappears during etching. 
     In etching of the memory hole, a substance derived from the plasma etching gas adheres to the sidewall, and a protective film is formed on the sidewall. Forming the protective film on the sidewall of the memory hole prevents etching of the sidewall, and suppresses the hole diameter from widening. When the protective film on the sidewall of the memory hole disappears, etching of the sidewall of the memory hole progresses, and the hole diameter of the memory hole widens. 
     The protective film formed on the sidewall of the memory hole is, for example, a fluorocarbon film containing carbon and fluorine. 
     The thickness of the protective film formed on the sidewall of the memory hole is determined by the balance between the amount of the substance adhering to the sidewall and the etching amount of the substance adhering to the sidewall. 
     For example, on the sidewall of a shallow portion of the memory hole, the plasma etching gas easily reaches, and the amount of the substance adhering to the sidewall increases. On the other hand, in the shallow portion of the memory hole, the amount of obliquely incident ions is large, and the time of being exposed to etching becomes long. For this reason, the etching amount of the substance adhering to the sidewall also increases. There is a risk that the etching amount exceeds the amount of the substance adhering to the sidewall, the protective film on the sidewall disappears, and the hole diameter of the memory hole widens. 
     For example, on the sidewall of a deep portion of the memory hole, the plasma etching gas hardly reaches, and the amount of the substance adhering to the sidewall decreases. Therefore, when the etching amount exceeds the amount of the substance adhering to the sidewall, there is a risk that the protective film on the sidewall disappears and the hole diameter of the memory hole widens. 
     In the manufacturing method for a semiconductor device according to the first embodiment, when the memory hole MH is formed, etching of the stacked body  40 , which is a layer to be processed, and treatment using the silylation agent are alternately performed. By the treatment using the silylation agent, the protective film is formed on the sidewall of the memory hole. By the treatment using the silylation agent, a new protective film is formed also in a portion where the protective film formed at the time of etching disappears. Therefore, it is considered that the shape of the memory hole can be suppressed from becoming a bowing shape. 
       FIGS. 7A to 7C  are explanatory views of the function of the manufacturing method for a semiconductor device of the first embodiment. 
     As shown in  FIG. 7A , a hydroxyl group (—OH) exists on the surfaces of the silicon oxide film  40   a  and the silicon nitride film  40   b  exposed on the sidewall of the memory hole MH. As shown in  FIG. 7B , in the manufacturing method for the nonvolatile memory  100  of the first embodiment, TMSDMA, which is a silylation agent, is supplied to the surface of the sidewall of the memory hole MH in the first treatment, the second treatment, and the third treatment. 
     As shown in  FIG. 7C , the Si—N bond of TMSDMA supplied to the surface of the sidewall of the memory hole 
     MH is broken, and a trimethylsilyl group is bonded to the surface of the sidewall. The trimethylsilyl group is bonded to the surface of the sidewall of the memory hole MH by a silylation reaction. 
     The protective film  44   a , the protective film  44   b , and the protective film  44   c  formed by the first treatment, the second treatment, and the third treatment include, for example, trimethylsilyl groups formed by the silylation reaction. 
     The silylation reaction is highly reactive and easily occurs even at a low temperature. For the silylation reaction, it is not necessary to bring the material into plasma and form ions and radicals. 
     Since the silylation reaction is highly reactive, the protective film is easily formed even in the deep portion of the memory hole MH. When the surface of the sidewall is completely covered with the trimethylsilyl group, the silylation reaction ends. Therefore, the formation of the protective film is a self-limiting process. Therefore, it is considered that the protective film  44   a , the protective film  44   b , and the protective film  44   c  formed on the sidewall by the first treatment, the second treatment, and the third treatment are formed to have uniform thicknesses. 
     It is considered that formation of the protective film  44   a , the protective film  44   b , and the protective film  44   c  suppresses etching of the sidewall, and can suppress the shape of the memory hole MH from becoming a bowing shape. 
     In the manufacturing method for the nonvolatile memory  100  of the first embodiment, the first etching, the first treatment, the second etching, the second treatment, the third etching, the third treatment, and the fourth etching are continuously performed in the identical chamber  20  of the identical RIE device. Therefore, the manufacturing time of the nonvolatile memory  100  is shortened, and an increase in the manufacturing cost of the nonvolatile memory  100  can be suppressed. 
     The first to fourth etching gases preferably contain oxygen. The first to fourth etching gases preferably contain oxygen gas. 
     When oxygen or oxygen gas is contained in the first to fourth etching gases, the surface of the silicon nitride film  40   b  on the sidewall of the memory hole MH is oxidized. Therefore, the surface state of the silicon oxide film  40   a  exposed to the sidewall resembles the surface state of the silicon nitride film  40   b . Therefore, the silylation reaction on the surface of the silicon oxide film  40   a  and the silylation reaction on the surface of the silicon nitride film  40   b  progress similarly. Therefore, the protective film  44   a , the protective film  44   b , and the protective film  44   c  become uniform films. Hence, the silicon nitride film  40   b  on the sidewall is suppressed from being selectively etched with respect to the silicon oxide film  40   a  on the sidewall. 
     The first to fourth etching gases preferably contain hydrogen. When the first to fourth etching gases contain hydrogen, the etching rate of the silicon nitride film  40   b  increases. Therefore, the etching time of the first to fourth etching can be shortened. 
     The first etching amount E 1  of the stacked body  40  in the first etching is preferably larger than the second etching amount E 2  of the stacked body  40  in the second etching. If the silylation reaction in the deep portion of the memory hole MH is suppressed, there is a risk that the protective film  44   b  in the deep portion of the memory hole MH becomes thin. By making the second etching amount E 2  smaller than the first etching amount El, etching of the sidewall in the second etching is suppressed. This can suppress the shape of the memory hole MH from becoming a bowing shape. The first etching amount E 1  may be equal to or smaller than the second etching amount E 2 . 
     In the first to fourth etching, the high-frequency power applied to the holder  22  on which the stacked body  40  is mounted is preferably equal to or more than 500 W, more preferably equal to or more than 750 W, and yet more preferably equal to or more than 1000 W. As the high-frequency power applied to the holder  22  becomes high, the energy of ions colliding with the stacked body  40  in the first to fourth etching becomes high. Therefore, it becomes easy to form the memory hole MH having a high aspect ratio. 
     As described above, according to the manufacturing method for a semiconductor device of the first embodiment, it is possible to suppress the shape of the memory hole from becoming a bowing shape, and to form the memory hole with high process accuracy. 
     Second Embodiment 
     The manufacturing method for a semiconductor device of the second embodiment is different from the manufacturing method of the first embodiment in that the first to third treatments are performed by a device different from the RIE device that performs the first to fourth etching processes. Hereinafter, part of description of the contents overlapping the first embodiment may be omitted. 
     In the manufacturing method for a semiconductor device of the second embodiment, the first to third treatments are performed using a wet etching device. 
     For example, after the first etching shown in  FIG. 3C , the silicon substrate  10  is taken out from the chamber  20  of the RIE device. Next, the first treatment is performed using the wet etching device. 
     For example, TMSDMA is applied to the surface of the silicon substrate  10 . For example, the silicon substrate  10  is immersed in TMSDMA. In the first treatment, TMSDMA is supplied as a liquid to the memory hole MH. 
     After the first treatment, the silicon substrate  10  is introduced into the chamber  20  of the RIE device, and the second etching is performed. 
     Thereafter, the second treatment is performed using the wet etching device, the third etching is performed using the RIE device, the third treatment is performed using the wet etching device, and the fourth etching is performed using the RIE device. 
     As described above, according to the manufacturing method for a semiconductor device of the second embodiment, similarly to the first embodiment, it is possible to suppress the shape of the memory hole from becoming a bowing shape, and to form the memory hole with high process accuracy. 
     Third Embodiment 
     The manufacturing method for a semiconductor device of the third embodiment is different from the manufacturing method of the first or second embodiment in that the treatment time of the first treatment and the treatment time of the second treatment are different. Hereinafter, part of description of the contents overlapping the first or second embodiment may be omitted. 
     In the manufacturing method for a semiconductor device of the third embodiment, for example, the treatment time of the second treatment is longer than the treatment time of the first treatment. The treatment time of the second treatment of forming the protective film  44   b  in the deep portion of the memory hole MH is made longer than the treatment time of the first treatment. By lengthening the treatment time of the second treatment, for example, the uniformity of the protective film  44   b  is improved. 
     In the manufacturing method for a semiconductor device of the third embodiment, for example, the treatment time of the second treatment is shorter than the treatment time of the first treatment. In the deep portion of the memory hole MH, the memory hole diameter sometimes becomes small due to a forward tapered shape of the memory hole MH. 
     By shortening the treatment time of the second treatment, the protective film  44   b  attached to a portion having a small memory hole diameter is thinned. By thinning the protective film  44   b , for example, it is possible to suppress reduction in the etching rate of the stacked body  40  in the third etching. 
     As described above, according to the manufacturing method for a semiconductor device of the third embodiment, similarly to the first or second embodiment, it is possible to suppress the shape of the memory hole from becoming a bowing shape, and to form the memory hole with high process accuracy. 
     Fourth Embodiment 
     The manufacturing method for a semiconductor device of the fourth embodiment is different from the manufacturing method of the first embodiment in that water is supplied to the recess after the first etching before the first treatment. Hereinafter, part of description of the contents overlapping the first embodiment may be omitted. 
     In the manufacturing method for a semiconductor device of the fourth embodiment, for example, water is supplied to the memory hole MH formed in the stacked body  40  after the first etching before the first treatment. 
     For example, after the first etching shown in FIG. 
       3 C, water is supplied from the third gas supply port  30   c  into the chamber  20 . Water is supplied as a gas into the chamber  20 . Water vapor is supplied into the chamber  20 . 
     Next, the first treatment shown in  FIG. 3D  is performed. 
     By supplying water to the memory hole MH after the first etching, for example, the area density and uniformity of the hydroxyl group (—OH) on the surface of the sidewall of the memory hole MH are increased. Therefore, the formation of the protective film  44   a  in the first treatment is promoted. 
     Therefore, for example, the uniformity of the protective film  44   a  is improved. Furthermore, for example, the treatment time of the first treatment can be shortened. 
     For example, water may be supplied to the memory holes MH formed in the stacked body  40  between the second etching and the second treatment and between the third etching and the third treatment. 
     As described above, according to the manufacturing method for a semiconductor device of the fourth embodiment, similarly to the first embodiment, it is possible to suppress the shape of the memory hole from becoming a bowing shape, and to form the memory hole with high process accuracy. 
     Fifth Embodiment 
     The manufacturing method for a semiconductor device of the fifth embodiment is different from the manufacturing method of the first embodiment in that oxygen is supplied to the recess after the first etching before the first treatment. Hereinafter, part of description of the contents overlapping the first embodiment may be omitted. 
     In the manufacturing method for a semiconductor device of the fifth embodiment, for example, oxygen is supplied to the memory hole MH formed in the stacked body  40  after the first etching before the first treatment. 
     For example, after the first etching shown in  FIG. 3C , oxygen gas is supplied from the third gas supply port  30   c  into the chamber  20 . High-frequency power is applied, and the oxygen gas becomes oxygen plasma in the chamber  20 . 
     Next, the first treatment shown in  FIG. 3D  is performed. 
     After the first etching, by supplying oxygen plasma to the memory hole MH, for example, oxidation of the surface of the silicon nitride film  40   b  on the sidewall of the memory hole MH progresses. Therefore, the surface state of the silicon oxide film  40   a  exposed to the sidewall resembles the surface state of the silicon nitride film  40   b . Therefore, the silylation reaction on the surface of the silicon oxide film  40   a  in the first treatment and the silylation reaction on the surface of the silicon nitride film  40   b  progress similarly. Therefore, the uniformity of the protective film  44   a  is improved. Hence, the silicon nitride film  40   b  on the sidewall is suppressed from being selectively etched with respect to the silicon oxide film  40   a  on the sidewall. 
     For example, oxygen may be supplied to the memory holes MH formed in the stacked body  40  between the second etching and the second treatment and between the third etching and the third treatment. 
     As described above, according to the manufacturing method for a semiconductor device of the fifth embodiment, similarly to the first embodiment, it is possible to suppress the shape of the memory hole from becoming a bowing shape, and to form the memory hole with high process accuracy. 
     Sixth Embodiment 
     The manufacturing method for a semiconductor device of the sixth embodiment is different from the manufacturing method of the first to fifth embodiments in that the layer to be processed is a single layer. Hereinafter, part of description of the contents overlapping the first to fifth embodiment may be omitted. 
     In the manufacturing method for a semiconductor device of the sixth embodiment, the layer to be processed is a single layer. In other words, there is no stacked structure in which the layer to be processed is formed of two or more types of different films. 
     The layer to be processed is, for example, an insulating layer of a single layer. The insulating layer is, for example, an oxide layer, a nitride layer, or an oxynitride layer. 
     The layer to be processed is, for example, a metal layer of a single layer. The layer to be processed is, for example, a semiconductor layer of a single layer. The semiconductor layer is, for example, a silicon layer of a single crystal or polycrystalline. 
     In the manufacturing method for a semiconductor device of the sixth embodiment, the pattern of the recess to be formed is, for example, a hole pattern or a groove pattern. 
     As described above, according to the manufacturing method for a semiconductor device of the sixth embodiment, by a function similar to that in the first to fifth embodiments, it is possible to suppress the shape of the memory hole from becoming a bowing shape, and to form the memory hole with high process accuracy. 
     In the first to fifth embodiments, the case where the etching is performed four times and the treatment of supplying the silylation agent between the etching is performed three times has been described by way of example. However, the number of times of etching is not limited to four and the number of times of the treatment of supplying the silylation agent is not limited to three. The number of times of etching may be any number as long as it is equal to or more than two, and the number of times of treatment of supplying the silylation agent may be any number as long as it is equal to or more than one. 
     In the first to fifth embodiments, the case where the semiconductor device is a nonvolatile memory has been described by way of example. However, the semiconductor device is not limited to a nonvolatile memory. 
     In the first embodiment, the case where the first film of the layer to be processed is a silicon oxide film and the second film is a silicon nitride film has been described by way of example. However, the first film and the second film are not limited to a combination of a silicon oxide film and a silicon nitride film as long as they are different films. For example, a combination of an insulating film and a semiconductor film, or a combination of an insulating film and a metal film may be adopted. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the manufacturing method for a semiconductor device described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the devices and methods described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.