Substrate processing method

Abstract

A substrate processing method according to an aspect of the present disclosure includes a laminated stack formation step, a removal step, and a metal film formation step. In the laminated stack formation step, an insulating film (L1) and a carbon-containing sacrificial film (L2) are alternately laminated on a substrate to form a laminated stack (LS) composed of a plurality of insulating films (L1) and a plurality of carbon-containing sacrificial films (L2). The removal step removes the plurality of carbon-containing sacrificial films (L2) in the laminated stack (LS). In the metal film formation step, a metal film that becomes a word line of a 3D-NAND memory is formed in a space (S) from which the plurality of carbon-containing sacrificial films (L2) have been removed.

Description

Substrate processing method

[0001] The disclosed embodiments relate to a method for processing a substrate.

[0002] A conventional technique involves forming a stack of silicon oxide films and silicon nitride films alternately stacked on a substrate, and selectively etching the silicon nitride films in the stack with an aqueous phosphoric acid solution. This technique also involves forming a metal film that serves as a word line in the space formed by the etching, thereby forming a 3D-NAND memory device structure (see, for example, Patent Document 1).

[0003] Special Publication No. 2020-529736

[0004] The present disclosure provides a technique that allows for efficient manufacturing of a device structure of a 3D-NAND memory.

[0005] A substrate processing method according to one aspect of the present disclosure includes a stack formation step, a removal step, and a metal film formation step. The stack formation step alternately stacks insulating films and carbon-containing sacrificial films on a substrate to form a stack composed of a plurality of insulating films and a plurality of carbon-containing sacrificial films. The removal step removes a plurality of the carbon-containing sacrificial films in the stack. The metal film formation step forms a metal film to become word lines of a 3D-NAND memory in spaces obtained by removing the plurality of carbon-containing sacrificial films.

[0006] According to the present disclosure, a device structure of a 3D-NAND memory can be efficiently manufactured.

[0007] FIG. 1 is a flowchart showing a procedure for substrate processing according to an embodiment. FIG. 2 is a schematic diagram of a stack formation apparatus according to an embodiment, as viewed from above. FIG. 3 is a diagram showing an example of the configuration of a liquid processing unit of the stack formation apparatus according to an embodiment. FIG. 4 is a diagram for explaining a stack formation process according to an embodiment. FIG. 5 is a diagram for explaining a stack formation process according to an embodiment. FIG. 6 is a diagram for explaining a groove formation process according to an embodiment. FIG. 7 is a schematic cross-sectional view of a substrate processing apparatus according to an embodiment, as viewed from above. FIG. 8 is a diagram showing an example of the configuration of a liquid processing unit. FIG. 9 is a schematic perspective view showing an example of the configuration of a drying unit. FIG. 10 is a diagram for explaining a removal process according to an embodiment. FIG. 11 is a diagram for explaining a liquid film formation process according to an embodiment. FIG. 12 is a diagram for explaining a drying process according to an embodiment.

[0008] Hereinafter, embodiments of the substrate processing method disclosed herein will be described in detail with reference to the accompanying drawings. Note that the present disclosure is not limited to the embodiments described below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of elements may differ from the actual situation. Furthermore, the drawings may include portions with different dimensional relationships and ratios.

[0009] A conventional technique involves forming a stack of silicon oxide films and silicon nitride films alternately stacked on a substrate, and selectively etching the silicon nitride films in the stack with an aqueous phosphoric acid solution. This technique then forms a metal film that serves as a word line in the space formed by the etching, thereby forming a device structure for a 3D-NAND memory.

[0010] However, in the above-described conventional technique, the substrate needs to be immersed in a hot phosphoric acid solution for a long time in order to sufficiently etch only the silicon nitride film in the stack. In other words, the above-described conventional technique requires a lot of labor in the manufacturing process of the 3D-NAND memory.

[0011] Therefore, it is expected that a technology capable of overcoming the above-mentioned problems and efficiently manufacturing a device structure of a 3D-NAND memory will be realized.

[0012] A procedure for substrate processing according to the embodiment will be described with reference to Fig. 1. Fig. 1 is a flowchart showing the procedure for substrate processing according to the embodiment. As shown in Fig. 1, in the substrate processing according to the embodiment, first, a stack formation process is performed to form a stack LS (see Fig. 5) on a wafer W (see Fig. 5) (step S101).

[0013] The multilayer stack forming apparatus 1 in which the process of step S101 is performed will be described with reference to Figures 2 and 3. Figure 2 is a schematic diagram of the multilayer stack forming apparatus 1 according to the embodiment, viewed from above.

[0014] 2, the laminated stack forming apparatus 1 includes a loading / unloading station 2 and a processing station 3. The loading / unloading station 2 and the processing station 3 are located adjacent to each other.

[0015] The loading / unloading station 2 is a carrier station for loading and unloading carriers C, and includes a carrier placement section 11 and a transport section 12. A plurality of carriers C, each containing a plurality of (e.g., 25) semiconductor wafers W (hereinafter also referred to as "wafers W") in a horizontal position, are placed on the carrier placement section 11. The wafers W are an example of substrates.

[0016] The transport section 12 is located adjacent to the carrier placement section 11. Inside the transport section 12, a transport device 13 is located.

[0017] The transfer device 13 includes a wafer holding mechanism that holds the wafer W. The transfer device 13 is capable of moving in horizontal and vertical directions and rotating about a vertical axis, and transfers the wafer W between the carrier C and the delivery unit 14 using the wafer holding mechanism.

[0018] Delivery unit 14 is located near load / unload station 2 in processing station 3. Transport device 15 is located, for example, in the center of processing station 3. Furthermore, in processing station 3, delivery unit 14, a plurality of liquid processing units 16, and a plurality of heating units 17 are located so as to surround transport device 15.

[0019] For example, a plurality of liquid processing units 16 are located on the right side of the loading / unloading station 2 when viewed from the rear, and a plurality of heating units 17 are located on the left side and rear side when viewed from the loading / unloading station 2 when viewed from the rear.

[0020] The liquid processing unit 16 forms a liquid film of a first processing liquid, which is a raw material for the insulating film L1 (see FIG. 4), on the wafer W. The liquid processing unit 16 also forms a liquid film of a second processing liquid, which is a raw material for the carbon-containing sacrificial film L2 (see FIG. 4), on the wafer W.

[0021] The heating unit 17 heats the wafer W, on which the liquid film of the first processing liquid has been formed, to a given temperature to form an insulating film L1 on the wafer W. The heating unit 17 also heats the wafer W, on which the liquid film of the second processing liquid has been formed, to a given temperature to form a carbon-containing sacrificial film L2 on the wafer W.

[0022] 3 is a diagram showing an example of the configuration of the liquid processing unit 16 of the layer stack forming apparatus 1 according to the embodiment. As shown in FIG. 3, the liquid processing unit 16 includes a substrate holding part 30, an outer cup 40, an inner cup 50, and a liquid supply part 60.

[0023] The substrate holding unit 30 holds and rotates the wafer W. The substrate holding unit 30 includes a spin chuck 31 and a drive unit 32. The spin chuck 31 holds the wafer W substantially horizontally. For example, the spin chuck 31 holds the wafer W by vacuum suction.

[0024] The drive unit 32 includes a motor (not shown) and is configured to be able to rotate the spin chuck 31 around a vertical axis. The drive unit 32 also includes a lift unit (not shown) and is configured to be able to lift and lower the spin chuck 31.

[0025] The outer cup 40 is positioned around the spin chuck 31. For example, when the wafer W is held by suction on the spin chuck 31, the outer cup 40 surrounds the side portion spanning from the wafer W to the spin chuck 31, and has a circular cross-sectional shape with a recess 41 formed along the entire lower periphery.

[0026] An exhaust pipe 43 forming an exhaust path connected to the suction mechanism 42 via an open / close valve V1 is connected to the bottom surface of the recess 41. In the exterior cup 40, the suction mechanism 42 and the exhaust pipe 43 form a suction exhaust path.

[0027] An opening 44 is formed in the upper central region of the outer cup 40, through which the wafer W can pass, and the inner peripheral edge of this opening 44 is located outside and near the outer peripheral edge of the wafer W held by the spin chuck 31.

[0028] A bottom plate 45 is positioned below the spin chuck 31 to surround the periphery of the spin chuck 31. The bottom plate 45 is connected to the recess 41 of the outer cup 40 in a region corresponding to the peripheral edge of the wafer W.

[0029] The inner cup 50 is located inside the outer cup 40. The inner cup 50 is located so as to substantially surround the region near the side of the outer peripheral edge of the wafer W held by the spin chuck 31 with a small gap therebetween, and has a circular cross-sectional shape.

[0030] The inner cup 50 has an opening 51. The opening 51 faces the outer peripheral edge of the wafer W held by the spin chuck 31 and opens in the vicinity of the outer peripheral edge over the entire periphery of the outer peripheral edge.

[0031] Upper wall portion 52 and lower wall portion 53 forming opening 51 gently slope downward as they extend outward from wafer W, and are connected to a liquid receiving portion 54 having a recessed shape that extends substantially vertically downward in correspondence with recess 41 inside outer cup 40. A drain pipe 55 is connected to the bottom surface of liquid receiving portion 54 via valve V2.

[0032] The inner peripheral edge of the upper wall portion 52 is located near the outer side and above the outer peripheral edge of the wafer W held by the spin chuck 31 so that the wafer W can pass inside the inner cup 50. On the other hand, the inner peripheral edge of the lower wall portion 53 extends into an area inside the outer peripheral edge of the back surface side of the wafer W held by the spin chuck 31. As a result, the inner cup 50 substantially surrounds the side portions of the outer peripheral edge of the wafer W with a small gap therebetween.

[0033] In the example of FIG. 3, the spin chuck 31 is raised above the outer cup 40 and the inner cup 50, and at this position the transfer device 15 (see FIG. 2) transfers the wafer W to the spin chuck 31.

[0034] Furthermore, a ring-shaped upright wall portion 56 is positioned on the upper surface of the bottom plate 45, and is concentric with the wafer W and has a smaller radius than the wafer W. This upright wall portion 56 is positioned, for example, inside the outer circumferential edge of the wafer W and erected so as to correspond to a position in the vicinity of and slightly inside the inner edge of the bottom wall portion 53. This upright wall portion 56 has ventilation holes 57 formed in a plurality of positions, for example, in the circumferential direction.

[0035] The liquid supply unit 60 supplies various processing liquids to the wafer W held on the spin chuck 31. The liquid supply unit 60 includes a first nozzle 61, a second nozzle 62, and a lower nozzle 63.

[0036] The first nozzle 61 supplies a first processing liquid, which is a raw material for the insulating film L1 (see FIG. 4), onto the upper surface of the wafer W. The first nozzle 61 is configured to be movable above the wafer W by a moving mechanism (not shown). The first processing liquid is, for example, a processing liquid, which is a raw material for an SOD (Spin On Dielectric) film.

[0037] The second nozzle 62 supplies a second processing liquid, which is a raw material for a carbon-containing sacrificial film L2 (see FIG. 4), onto the upper surface of the wafer W. The second nozzle 62 is configured to be movable above the wafer W by a movement mechanism (not shown). The second processing liquid is, for example, a processing liquid that is a raw material for an SOC (Spin On Carbon) film.

[0038] The lower nozzle 63 is located closer to the center than the upright wall portion 56 on the upper surface of the bottom plate 45, and is arranged so as to incline upward and outward. The lower nozzle 63 ejects the cleaning liquid from an ejection hole at the tip toward the small gap between the wafer W and the lower wall portion 53 of the inner cup 50.

[0039] The flow of wafers W in the layer stack forming apparatus 1 will be described with reference to FIGS. 4 and 5 in addition to FIGS. 2 and 3 described above.

[0040] First, a carrier C storing a plurality of wafers W is carried into the carrier mounting section 11 from the outside by an automatic transfer robot (or an operator), and the wafers W are removed from the carrier C by the transfer device 13. The wafers W are transferred from the transfer device 13 to the transfer device 15 via the delivery section 14.

[0041] Next, the wafer W is transferred by the transfer device 15 to one of the liquid processing units 16, where a liquid film of the first processing liquid is formed on the upper surface. Next, the wafer W on which the liquid film of the first processing liquid has been formed is transferred by the transfer device 15 to one of the heating units 17. Then, an insulating film L1 is formed on the upper surface of the wafer W that has been heat-treated inside the heating unit 17, as shown in FIG.

[0042] Next, the wafer W is transferred by the transfer device 15 to one of the liquid processing units 16, where a liquid film of the second processing liquid is formed on the insulating film L1. Next, the wafer W on which the liquid film of the second processing liquid has been formed is transferred by the transfer device 15 to one of the heating units 17. Then, a carbon-containing sacrificial film L2 is formed on the insulating film L1 of the wafer W that has been heat-treated inside the heating unit 17, as shown in FIG.

[0043] 5, the wafer W is alternately transported between the liquid processing unit 16 and the heating unit 17, whereby insulating films L1 and carbon-containing sacrificial films L2 are alternately stacked on the wafer W. In this way, the stack formation apparatus 1 forms a stack LS on the wafer W, which is composed of a plurality of insulating films L1 and a plurality of carbon-containing sacrificial films L2.

[0044] The wafer W on which the layer stack LS has been formed is transferred from the transfer device 15 to the transfer device 13 via the delivery unit 14, and is returned to the inside of the original carrier C, for example.

[0045] In the embodiment described above, the insulating film L1 is an SOD film, but the present disclosure is not limited to this example. The insulating film L1 may be any thin film having insulating properties, such as a SiO ２ The film may be a film, a SiN film, a SiC film, a SiOC film, a SiON film, a SiOCN film, an aC (amorphous carbon) film, an alumina film, or the like.

[0046] Furthermore, in the above embodiment, an example in which the insulating film L1 is formed by a wet process is shown, but the present disclosure is not limited to such an example, and for example, the insulating film L1 may be formed by a dry process (such as a CVD (Chemical Vapor Deposition) method or a sputtering method).

[0047] In the above embodiment, the carbon-containing sacrificial film L2 is formed of an SOC film, but the present disclosure is not limited to this example. The carbon-containing sacrificial film L2 has properties different from those of the insulating film L1, and may be any thin film that contains carbon and can be easily removed by the removal process described below, such as an organic resin film or an a-C film.

[0048] More specifically, there are many types of carbon films, including diamond films, hydrogen-containing a-C films, a-C films, SOC films, graphite films, photoresist films, and other organic films, and their properties vary greatly. For example, the insulating film L1 may be a diamond film, hydrogen-containing a-C film, a-C film, or SOC film, which has high electrical resistivity and is difficult to remove even by removal processing, and the carbon-containing sacrificial film L2 may be any thin film that can be easily removed by removal processing.

[0049] Furthermore, in the above embodiment, an example in which the carbon-containing sacrificial film L2 is formed by a wet process has been described, but the present disclosure is not limited to such an example, and for example, the carbon-containing sacrificial film L2 may be formed by a dry process (such as a CVD method or a sputtering method).

[0050] 1 , in the substrate processing according to the embodiment, following the stack formation process (step S101) described above, a hole formation process is performed (step S102). In the hole formation process, a plurality of holes are formed in the stack LS on the wafer W, penetrating the stack LS.

[0051] The hole formation process is performed by, for example, dry etching the stack LS. For example, when the insulating film L1 is a carbon-based thin film, the insulating film L1 and the carbon-containing sacrificial film L2 can be etched together using an oxygen-based etching gas.

[0052] In addition, when the insulating film L1 is a thin film other than a carbon-based film, the stack LS can be etched layer by layer by alternately supplying an etching gas for the insulating film L1 and an oxygen-based etching gas for the carbon-containing sacrificial film L2 into the chamber. In this case, the etching gas for the insulating film L1 can be, for example, a fluorine-based etching gas.

[0053] Next, in the substrate processing according to the embodiment, a channel formation process is performed (step S103). In the channel formation process, for example, a channel of a 3D-NAND memory is formed inside the hole formed in the hole formation process by a conventionally known technique.

[0054] Next, in the substrate processing according to the embodiment, a trim etching process is performed (step S104). In this trim etching process, for example, a staircase-like structure is formed on the device periphery of a 3D-NAND memory by a conventionally known trim etching process.

[0055] Next, in the substrate processing according to the embodiment, a groove forming process is performed (step S105). In the groove forming process, a groove T is formed in the stack LS on the wafer W, penetrating the stack LS, as shown in FIG.

[0056] The groove formation process is performed by, for example, dry etching the stack LS. When the insulating film L1 is a carbon-based thin film, the insulating film L1 and the carbon-containing sacrificial film L2 can be etched together using an oxygen-based etching gas.

[0057] Furthermore, when the insulating film L1 is a thin film other than a carbon-based film, the stack LS can be etched layer by layer by alternately supplying an etching gas for the insulating film L1 and an oxygen-based etching gas for the carbon-containing sacrificial film L2 into the chamber.

[0058] Returning to the description of Fig. 1, next, in the substrate processing according to the embodiment, a removal process is performed to selectively remove the carbon-containing sacrificial film L2 in the stack LS on the wafer W (step S106).

[0059] The substrate processing apparatus 100 in which the process of step S106 and subsequent processes described below are performed will be described with reference to FIGS.

[0060] 7 to 9, in order to clarify the positional relationships, mutually orthogonal X-, Y-, and Z-axes are defined, and the positive direction of the Z-axis is defined as the vertically upward direction.

[0061] 7, the substrate processing apparatus 100 includes a loading / unloading station 102 and a processing station 103. The loading / unloading station 102 and the processing station 103 are located adjacent to each other.

[0062] The loading / unloading station 102 includes a carrier placement unit 111 and a transfer unit 112. A plurality of carriers C, each accommodating a plurality of wafers W in a horizontal state, are placed on the carrier placement unit 111.

[0063] The transport section 112 is located adjacent to the carrier placement section 111. Inside the transport section 112, a transport device 113 and a delivery section 114 are located.

[0064] The transfer device 113 includes a wafer holding mechanism that holds the wafer W. The transfer device 113 is capable of moving in the horizontal and vertical directions and rotating about a vertical axis, and transfers the wafer W between the carrier C and the delivery unit 114 using the wafer holding mechanism.

[0065] The processing station 103 is located adjacent to the transport section 112. The processing station 103 includes a transport block 104 and a processing block 105.

[0066] The transfer block 104 includes a transfer area 115 and a transfer device 116. The transfer area 115 is, for example, a rectangular parallelepiped region extending along the arrangement direction (X-axis direction) of the loading / unloading stations 102 and the processing stations 103. The transfer device 116 is located in the transfer area 115.

[0067] The transfer device 116 includes a wafer holding mechanism that holds the wafer W. The transfer device 116 is capable of moving in the horizontal and vertical directions and rotating about a vertical axis, and transfers the wafer W between the delivery unit 114 and the processing block 105 using the wafer holding mechanism.

[0068] The processing block 105 is located adjacent to the transfer area 115 on one side thereof. Specifically, the processing block 105 is located on one side (the negative Y-axis direction in the drawing) of the transfer area 115 in a direction (Y-axis direction) perpendicular to the arrangement direction (X-axis direction) of the loading / unloading station 102 and the processing station 103. The processing block 105 is also arranged in multiple stages (for example, three stages) along the vertical direction.

[0069] As described above, in the substrate processing apparatus 100 according to this embodiment, the processing blocks 105 are arranged in multiple stages on one side of the transfer block 104. The wafers W are transferred between the processing blocks 105 located on each stage and the delivery part 114 by a common transfer device 116 located in the transfer block 104.

[0070] The processing block 105 includes a liquid processing unit 117 and a drying unit 118. The liquid processing unit 117 performs a process of selectively removing the carbon-containing sacrificial film L2 from the layer stack LS on the wafer W. Furthermore, the liquid processing unit 117 performs a process of forming a liquid film on the upper surface of the wafer W after the chemical liquid processing. The configuration of the liquid processing unit 117 will be described later.

[0071] The drying unit 118 performs a supercritical drying process on the wafer W after the liquid film formation process. Specifically, the drying unit 118 dries the wafer W by bringing the wafer W after the liquid film formation process into contact with a processing fluid in a supercritical state (hereinafter also referred to as a "supercritical fluid"). The configuration of the drying unit 118 will be described later.

[0072] 7, the substrate processing apparatus 100 has a supply unit that supplies a processing fluid in a supercritical state to the drying unit 118. Specifically, the supply unit includes a group of supply devices including a flow meter, a flow regulator, a back pressure valve, a heater, etc., and a housing that houses the group of supply devices. In this embodiment, the supply unit supplies CO 2 as the processing fluid. ２ is fed to the drying unit 118.

[0073] Liquid treatment unit 117 and drying unit 118 are arranged along transport area 115 (i.e., along the X-axis direction). Of liquid treatment unit 117 and drying unit 118, liquid treatment unit 117 is arranged at a position close to load / unload station 102, and drying unit 118 is arranged at a position far from load / unload station 102.

[0074] In this manner, one processing block 105 includes one liquid processing unit 117 and one drying unit 118. That is, the substrate processing apparatus 100 is provided with the same number of liquid processing units 117 and drying units 118.

[0075] 8 is a diagram showing an example of the configuration of liquid processing unit 117. Liquid processing unit 117 is configured, for example, as a single-wafer liquid processing apparatus that performs liquid processing on wafers W one by one.

[0076] As shown in FIG. 8, the liquid processing unit 117 holds the wafer W almost horizontally using a wafer holding mechanism 125 located in an outer chamber 123 that forms the processing space, and rotates the wafer W by rotating this wafer holding mechanism 125 around a vertical axis.

[0077] Liquid processing unit 117 is configured such that nozzle arm 126 is inserted above rotating wafer W, and chemical liquid or rinse liquid can be supplied from chemical liquid nozzle 126 a located at the tip of nozzle arm 126 .

[0078] Liquid processing unit 117 also has a chemical liquid supply path 125a formed inside wafer holding mechanism 125. Liquid processing unit 117 is configured so that chemical liquids and rinse liquids can be supplied from chemical liquid supply path 125a.

[0079] The various chemical liquids supplied to the wafer W are received by the outer chamber 123 and the inner cup 124 located within the outer chamber 123. The various chemical liquids received are discharged from a drain port 123a located at the bottom of the outer chamber 123 and a drain port 124a located at the bottom of the inner cup 124.

[0080] Furthermore, the atmosphere inside the outer chamber 123 is exhausted from an exhaust port 123 b located at the bottom of the outer chamber 123 .

[0081] 9 is a schematic perspective view showing an example of the configuration of the drying unit 118. The drying unit 118 has a main body 131, a holding plate 132, and a lid member 133. The housing-like main body 131 has an opening 134 formed therein for loading and unloading a wafer W. The holding plate 132 holds the wafer W to be processed in a horizontal position. The lid member 133 supports the holding plate 132 and also seals the opening 134 when the wafer W is loaded into the main body 131.

[0082] Main body 131 is a container having a processing space formed therein that can accommodate a wafer W having a diameter of, for example, 300 mm, and has supply ports 135 and 136 and a discharge port 137 located on its wall. Supply ports 135 and 136 and discharge port 137 are connected to a supply flow path and a discharge flow path, respectively, for circulating a supercritical fluid to drying unit 118.

[0083] Supply port 135 is connected to the side surface of housing-like main body 131 opposite to opening 134. Supply port 136 is connected to the bottom surface of main body 131. Discharge port 137 is connected to the lower side of opening 134. Note that although two supply ports 135, 136 and one discharge port 137 are illustrated in Figure 9, the numbers of supply ports 135, 136 and discharge ports 137 are not particularly limited.

[0084] Also, fluid supply headers 138, 139 and a fluid discharge header 140 are located inside the main body 131. The fluid supply headers 138, 139 are formed with a plurality of supply ports aligned in the longitudinal direction of the fluid supply headers 138, 139, and the fluid discharge header 140 is formed with a plurality of discharge ports aligned in the longitudinal direction of the fluid discharge header 140.

[0085] The fluid supply header 138 is connected to the supply port 135 and is located adjacent to the side surface opposite the opening 134 inside the housing-like main body 131. Furthermore, a plurality of supply ports formed side by side on the fluid supply header 138 face the opening 134 side.

[0086] The fluid supply header 139 is connected to the supply port 136 and is located at the center of the bottom surface inside the housing-like main body 131. A plurality of supply ports formed side by side on the fluid supply header 139 face upward.

[0087] The fluid discharge header 140 is connected to the discharge port 137, and is located inside the housing-like main body 131 adjacent to the side surface on the opening 134 side and below the opening 134. Furthermore, a plurality of discharge ports formed in line on the fluid discharge header 140 face upward.

[0088] The fluid supply headers 138 and 139 supply the supercritical fluid into the main body 131. The fluid discharge header 140 guides the supercritical fluid in the main body 131 to the outside of the main body 131 and discharges it. The supercritical fluid discharged to the outside of the main body 131 via the fluid discharge header 140 includes IPA liquid dissolved in the supercritical fluid in a supercritical state from the top surface of the wafer W.

[0089] The flow of wafers W in the substrate processing apparatus 100 will be described with reference to FIGS. 1 and 10 to 12 in addition to FIGS. 7 to 9 described above.

[0090] First, a carrier C storing a plurality of wafers W is carried into the carrier mounting section 111 from the outside by an automatic transfer robot (or an operator), and the wafers W are removed from the carrier C by the transfer device 113. The wafers W are transferred from the transfer device 113 to the transfer device 116 via the delivery section 114.

[0091] Next, the wafer W is transferred by the transfer device 116 to the liquid processing unit 117, where a removal process is performed (step S106 (see FIG. 1)). Specifically, in the removal process according to this embodiment, a third processing liquid A3 (see FIG. 10) is supplied from a chemical liquid nozzle 126a (see FIG. 8) to the upper surface of the wafer W on which the stacked layer LS is formed. The third processing liquid A3 is an example of a removal process liquid.

[0092] The third processing liquid A3 is a processing liquid that removes the carbon-containing sacrificial film L2 in the stack LS on the wafer W, but does not remove the insulating film L1 in the stack LS. As the third processing liquid A3 according to the embodiment, for example, an organic solvent or ozone water can be used.

[0093] In the embodiment, as shown in FIG. 10, by supplying a third processing liquid A3 to the upper surface of the wafer W, the third processing liquid A3 penetrates into the inside of the stack LS through the trench T or the like, and selectively removes a plurality of carbon-containing sacrificial films L2 (see FIG. 6).

[0094] As described above, in the embodiment, the carbon-containing sacrificial film L2 is used as the sacrificial film that is selectively removed from the stacked layer LS, which is an intermediate product of the 3D-NAND memory, and the carbon-containing sacrificial film L2 is removed by liquid treatment using the third treatment liquid A3.

[0095] This allows the sacrificial film in the stack LS to be efficiently removed. Therefore, according to the embodiment, the device structure of the 3D-NAND memory can be efficiently manufactured.

[0096] In the above embodiment, the carbon-containing sacrificial film L2 is selectively removed by supplying the third processing liquid A3 to the upper surface of the wafer W. However, the present disclosure is not limited to this example. For example, the carbon-containing sacrificial film L2 may be selectively removed by supplying a processing gas (e.g., ozone gas) to the upper surface of the wafer W.

[0097] When processing with ozone gas, the wafer W or the ozone gas may be heated to enhance the removal performance. Furthermore, the wafer W or the ozone gas may be irradiated with ultraviolet light to enhance the removal performance.

[0098] This also makes it possible to efficiently remove the sacrificial film in the stack LS, thereby enabling the device structure of the 3D-NAND memory to be manufactured efficiently.

[0099] Returning to the description of FIG. 1 , next, in the substrate processing according to the embodiment, a rinse process is performed (step S107). Specifically, in the rinse process according to the embodiment, a rinse liquid is supplied from chemical liquid nozzle 126 a and chemical liquid supply path 125 a (see FIG. 8 ) to the upper and lower surfaces of wafer W that have been subjected to the removal process. This removes third processing liquid A3 from the surface of wafer W.

[0100] Next, in the substrate processing according to the embodiment, a liquid film forming process is performed (step S108). Specifically, in the liquid film forming process according to the embodiment, a fourth processing liquid A4 (see FIG. 11 ) is supplied from the chemical liquid nozzle 126 a and the chemical liquid supply path 125 a to the upper and lower surfaces of the wafer W that has been subjected to the rinsing process. The fourth processing liquid A4 is an example of a puddle liquid.

[0101] As a result, the rinse liquid remaining on both surfaces of the wafer W is replaced with the fourth processing liquid A4. Thereafter, the liquid processing unit 117 gently stops the rotation of the wafer holding mechanism 125. As a result, a liquid film of the fourth processing liquid A4 is formed on the upper surface of the wafer W, as shown in FIG.

[0102] As the fourth treatment liquid A4 according to the embodiment, for example, IPA (isopropyl alcohol) in a liquid state (hereinafter also referred to as "IPA liquid") can be used.

[0103] After the liquid film forming process, the wafer W, with the liquid film of fourth processing liquid A4 formed on its upper surface, is transferred to transfer device 116 by a transfer mechanism (not shown) provided in wafer holding mechanism 125, and is unloaded from liquid processing unit 117. Then, the wafer W unloaded from liquid processing unit 117 is transferred to drying unit 118.

[0104] The liquid film formed on the wafer W prevents the pattern of the insulating film L1 from collapsing due to evaporation (vaporization) of the liquid on the top surface of the wafer W during transport of the wafer W from the liquid processing unit 117 to the drying unit 118 or during loading into the drying unit 118.

[0105] Next, in the substrate processing according to the embodiment, a drying process is performed (step S109). Specifically, in the drying process according to the embodiment, a supercritical fluid in a high-pressure state (for example, about 16 MPa) is supplied into the main body 131 of the drying unit 118, and the high-pressure supercritical fluid is brought into contact with the wafer W on which the liquid film of the fourth processing liquid A4 has been formed.

[0106] In the drying unit 118, the fourth processing liquid A4 between the patterns of the insulating film L1 formed on the wafer W comes into contact with the high-pressure supercritical fluid, and gradually dissolves in the supercritical fluid, gradually replacing the spaces between the patterns of the insulating film L1 with the supercritical fluid, until the spaces between the patterns of the insulating film L1 are finally filled with only the supercritical fluid.

[0107] After the fourth processing liquid A4 is removed from between the patterns of the insulating film L1, the pressure inside the main body 131 is reduced from a high pressure state to atmospheric pressure.２ changes from a supercritical state to a gaseous state, and the spaces between the patterns of the insulating film L1 are occupied only by the gas.

[0108] In this way, the fourth processing liquid A4 between the patterns of the insulating film L1 is removed, and spaces S are formed between adjacent insulating films L1, as shown in Fig. 12. Then, the drying process of the wafer W is completed.

[0109] Here, the supercritical fluid has a lower viscosity than a liquid (e.g., IPA liquid) and has a high ability to dissolve liquids, and in addition, there is no interface between the supercritical fluid and the liquid or gas in equilibrium.

[0110] As a result, in the drying process using the supercritical fluid, the liquid can be dried without being affected by the surface tension, and therefore, according to the embodiment, it is possible to prevent the pattern of the insulating film L1 from collapsing during the drying process.

[0111] In the above embodiment, IPA liquid is used as the fourth treatment liquid A4 for preventing drying, and CO in a supercritical state is used as the treatment fluid. ２ However, the present disclosure is not limited to such an example. For example, in the present disclosure, a fourth treatment liquid A4 other than the IPA liquid may be used as a liquid for preventing drying, or CO 2 in a supercritical state may be used. ２ Fluids other than the above may also be used as the processing fluid.

[0112] In addition, in the above embodiment, an example in which the wafer W is dried using a processing fluid in a supercritical state has been described, but the present disclosure is not limited to such an example. For example, in the present disclosure, the wafer W may be dried using a surface molecular dry (SMD) process in which a chemical solution containing a hydrophobizing agent is supplied to the upper surface of the rinsed wafer W to hydrophobize the surface of the insulating film L1 and then dried. This also makes it possible to prevent the pattern of the insulating film L1 from collapsing during the drying process.

[0113] On the other hand, by drying the wafer W using a processing fluid in a supercritical state as in the above embodiment, even if the insulating film L1 and the carbon-containing sacrificial film L2 are thinned to increase the integration density of the 3D-NAND memory, it is possible to prevent the pattern of the insulating film L1 from collapsing during the drying process.

[0114] Continuing with the description of the flow of wafers W within the substrate processing apparatus 100, the wafers W that have been dried in the drying unit 118 are transferred from the transfer device 116 to the transfer device 113 via the delivery unit 114, and are returned to, for example, the inside of the original carrier C.

[0115] Returning to the explanation of FIG. 1 , following the drying process described above, the substrate processing according to the embodiment involves a metal film formation process (step S110). In this metal film formation process, for example, a metal film that will become the word lines of the 3D-NAND memory is formed inside the space S formed by the drying process using a conventionally known technique. This metal film is composed mainly of, for example, tungsten.

[0116] In the present disclosure, the film formed inside the space S formed by the drying process is not limited to a metal film that becomes the word line of the 3D-NAND memory, but may be a barrier metal film that suppresses diffusion of the gate insulating film or word line material of the 3D-NAND memory.

[0117] Finally, in the substrate processing according to the embodiment, a device structure forming process for forming the remaining device structure of the 3D-NAND memory is performed by a conventionally known technique (step S111), and a series of substrate processing steps is completed.

[0118] The substrate processing method according to the embodiment includes a stack formation step (step S101), a removal step (step S106), and a metal film formation step (step S110). The stack formation step (step S101) alternately stacks insulating films L1 and carbon-containing sacrificial films L2 on a substrate (wafer W) to form a stack LS composed of a plurality of insulating films L1 and a plurality of carbon-containing sacrificial films L2. The removal step (step S106) removes the plurality of carbon-containing sacrificial films L2 from the stack LS. The metal film formation step (step S110) forms a metal film that will become the word lines of the 3D-NAND memory in the space S from which the plurality of carbon-containing sacrificial films L2 have been removed. This allows for efficient fabrication of a 3D-NAND memory device structure.

[0119] The substrate processing method according to the embodiment further includes a liquid film forming step (step S108) and a drying step (step S109). The liquid film forming step (step S108) forms a liquid film on the substrate (wafer W) after the removing step (step S106). The drying step (step S109) dries the substrate (wafer W) on which the liquid film has been formed. This makes it possible to prevent the pattern from collapsing during the drying process.

[0120] In the substrate processing method according to the embodiment, the liquid film forming step (step S108) replaces the removal processing liquid (third processing liquid A3) used in the removal step (step S106) with a puddle liquid (fourth processing liquid A4) to form a liquid film with the puddle liquid (fourth processing liquid A4). The puddle liquid (fourth processing liquid A4) is IPA. This prevents the pattern of the insulating film L1 from collapsing during the drying process.

[0121] In the substrate processing method according to the embodiment, the drying step (step S109) dries the substrate (wafer W) by bringing a processing fluid in a supercritical state into contact with the substrate (wafer W). This makes it possible to prevent the pattern of the insulating film L1 from collapsing during the drying process.

[0122] In the substrate processing method according to the embodiment, the removal step (step S106) removes the carbon-containing sacrificial film L2 with an organic solvent, thereby efficiently removing the sacrificial film in the stack LS.

[0123] In the substrate processing method according to the embodiment, the removal step (step S106) removes the carbon-containing sacrificial film L2 with ozone water, thereby making it possible to efficiently remove the sacrificial film in the stack LS.

[0124] In the substrate processing method according to the embodiment, the removal step (step S106) removes the carbon-containing sacrificial film L2 with ozone gas, thereby efficiently removing the sacrificial film in the stack LS.

[0125] In the substrate processing method according to the embodiment, the stack formation step (step S101) forms the carbon-containing sacrificial film L2 by a wet process and also forms the insulating film L1 by another wet process, thereby enabling efficient formation of the stack LS.

[0126] In the substrate processing method according to the embodiment, the stack formation step (step S101) forms the carbon-containing sacrificial film L2 by a wet process and the insulating film L1 by a dry process, thereby forming a stable insulating film L1.

[0127] In the substrate processing method according to the embodiment, the stack formation step (step S101) forms the carbon-containing sacrificial film L2 by a dry process and the insulating film L1 by another dry process, thereby enabling efficient formation of the stack LS.

[0128] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0129] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0130] W: wafer (an example of a substrate) L1: insulating film L2: carbon-containing sacrificial film LS: laminated stack S: space A3: third processing liquid (an example of a removal processing liquid) A4: fourth processing liquid (an example of a puddle liquid)

Claims

1. A substrate processing method including: a laminate stack formation step of alternately laminating insulating films and carbon-containing sacrificial films on a substrate to form a laminate stack composed of a plurality of the insulating films and a plurality of the carbon-containing sacrificial films; a removal step of removing the plurality of carbon-containing sacrificial films from the laminate stack; and a metal film formation step of forming a metal film to become a word line of a 3D-NAND memory in a space from which the plurality of carbon-containing sacrificial films have been removed.

2. The substrate processing method according to claim 1, further comprising, after the removing step, a liquid film forming step of forming a liquid film on the substrate, and a drying step of drying the substrate on which the liquid film has been formed.

3. The substrate processing method according to claim 2, wherein the liquid film forming step replaces the removal processing liquid used in the removal step with a puddle liquid to form the liquid film with the puddle liquid, and the puddle liquid is IPA.

4. The substrate processing method according to claim 3, wherein the drying step dries the substrate by contacting a processing fluid in a supercritical state with the substrate.

5. The substrate processing method according to any one of claims 1 to 4, wherein the removing step removes the carbon-containing sacrificial film with an organic solvent.

6. The substrate processing method according to any one of claims 1 to 4, wherein the removing step removes the carbon-containing sacrificial film with ozone water.

7. The substrate processing method according to any one of claims 1 to 4, wherein the removing step removes the carbon-containing sacrificial film with ozone gas.

8. The substrate processing method according to any one of claims 1 to 4, wherein the lamination stack forming step forms the carbon-containing sacrificial film by a wet process and forms the insulating film by another wet process.

9. The substrate processing method according to any one of claims 1 to 4, wherein the lamination stack formation step forms the carbon-containing sacrificial film by a wet process and forms the insulating film by a dry process.

10. The substrate processing method according to any one of claims 1 to 4, wherein the lamination stack forming step forms the carbon-containing sacrificial film by a dry process and forms the insulating film by another dry process.

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