SUBSTRATE PROCESSING METHOD AND SUBSTRATE PROCESSING APPARATUS

Abstract

To provide a substrate processing method and a substrate processing apparatus capable of suppressing shape abnormalities of patterns formed on a substrate.SOLUTION: A substrate processing method includes the steps of: a) providing a substrate including a film to be etched, a first mask formed on the film to be etched, and a second mask formed on the first mask and having a film type different from that of the first mask and having apertures; b) selectively etching the first mask against the second mask to form an aperture in which at least a portion of the first mask has a larger aperture dimension than the aperture dimension of the bottom of the second mask, and c) etching the film to be etched.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus. [Background technology]

[0002] As semiconductor device integration progresses not only horizontally but also vertically, the aspect ratio of the patterns formed during the semiconductor device manufacturing process is also increasing. For example, in the manufacture of 3D NAND, a channel hole is formed in a direction that penetrates multiple metal wiring layers. When forming a 64-layer memory cell, the aspect ratio of the channel hole is 45.

[0003] Various methods have been proposed to form high aspect ratio patterns with high accuracy, such as a method of suppressing lateral etching by repeatedly performing etching and deposition in an opening formed in a dielectric material of a semiconductor substrate (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2016 / 0343580 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a substrate processing method and a substrate processing apparatus capable of suppressing shape abnormalities in a pattern formed on a substrate. [Means for solving the problem]

[0006] A substrate processing method according to one embodiment of the present disclosure includes the steps of: a) providing a substrate including a film to be etched, a first mask formed on the film to be etched, and a second mask formed on the first mask, the second mask being of a different film type than the first mask and having an opening; b) etching the first mask selectively with respect to the second mask to form an opening in which at least a portion of the first mask has an opening dimension larger than an opening dimension at a bottom of the second mask; and c) etching the film to be etched. Effect of the Invention

[0007] According to the present disclosure, shape abnormalities in a pattern formed on a substrate can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of CD when a vertical mask and a tapered mask are used. [Diagram 2] FIG. 2 is a flowchart illustrating an example of a substrate processing method according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 is a diagram showing an example of a pattern formed by the substrate processing method according to the present embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a pattern structure targeted in this embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of experimental results of an example and a comparative example in this embodiment. [Figure 6] FIG. 6 is a diagram showing an example of a substrate processing apparatus according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a substrate processing method and a substrate processing apparatus will be described in detail with reference to the accompanying drawings. Note that the disclosed technology is not limited to the following preferred embodiments.

[0010] In the following description, the term "pattern" refers to a shape formed on a substrate in general. The pattern refers to the entirety of a plurality of shapes formed on a substrate, such as holes, trenches, and lines and spaces. The term "opening" refers to a portion of a pattern formed on a substrate that is recessed in the thickness direction of the substrate. The opening has a "sidewall" that is the inner peripheral surface of the recessed shape, a "bottom" that is the bottom part of the recessed shape, and a "top" that is the substrate surface adjacent to the sidewall and that is continuous with the sidewall. The lateral dimension of the space formed by the opening is called the "opening dimension." The term "opening" is also used to refer to the entire space surrounded by the bottom and sidewall, or any position in the space.

[0011] The "vertical direction" refers to the film thickness direction of multiple films formed on a substrate. The vertical direction is a direction approximately perpendicular to the substrate surface. The "lateral direction" refers to a direction parallel to the substrate surface. The lateral direction is approximately perpendicular to the vertical direction. Note that the vertical direction and the lateral direction do not strictly refer to only one direction, but allow for a certain degree of error.

[0012] When etching a vertical pattern with a high aspect ratio on a film to be etched, it is considered preferable that the opening in the mask has a vertical bottom rather than a tapered bottom. However, in the portion of the film to be etched directly under the mask, a protective film or deposits during etching may adhere to the mask, resulting in a large Bar-CD (Critical Dimension). Here, Bar-CD represents the dimension of the portion that remains unetched (hereinafter also referred to as a bar). The dimension of the opening to be etched is represented as Space-CD. It is expected that the vertical processability of the pattern formed on the substrate can be improved to suppress shape abnormalities of the pattern.

[0013] [CD when using vertical and tapered masks] First, the CD when a vertical mask and a tapered mask are used will be described with reference to FIG. 1. FIG. 1 is a diagram showing an example of the CD when a vertical mask and a tapered mask are used. FIG. 1A shows the case when a vertical mask is used. In the substrate 100 shown in FIG. 1A, an etching target film 102 and a mask 103 are formed on an undercoat film 101. The mask 103 has a vertical sidewall at the bottom of an opening. When etching is performed on the substrate 100, the bar 102a of the etching target film 102 has a CD104 directly below the mask 103 and a CD105 at the top that are larger than the CD106 in the middle and the CD107 at the bottom. Here, CD104 to 107 are Bar-CDs, and CD108 of the etched hole is Space-CD.

[0014] FIG. 1B shows a case where a tapered mask is used. In the substrate 110 shown in FIG. 1B, an etching target film 112 and a mask 113 are formed on an undercoat film 111. The mask 113 has a tapered side wall at the bottom of the opening. When etching is performed on the substrate 110, the bar 112a of the etching target film 112 has a CD 114 directly below the mask 113 that is larger than the CD 115 at the top, the CD 116 at the middle, and the CD 117 at the bottom. Here, CDs 114 to 117 are Bar-CDs, and the CD 118 of the etched hole is Space-CD. As shown in FIGS. 1A and 1B, when a vertical mask or a tapered mask is used, the vertical processability directly below the mask may be reduced.

[0015] [Substrate Processing Method in the Present Embodiment] Next, a substrate processing method according to the present embodiment will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a flow chart showing an example of the substrate processing method according to an embodiment of the present disclosure. Fig. 3 is a diagram showing an example of a pattern formed by the substrate processing method according to the present embodiment.

[0016] As shown in Fig. 2, first, a substrate 200 is provided as an object to be processed (step S1). As shown in Fig. 3A, the substrate 200 has an etching target film 202, a first mask 203, and a second mask 204 formed on an undercoat film 201. The second mask 204 is made of a different film type from the first mask 203.

[0017] Next, the opening 205 is formed in the second mask 204 (step S2). In step S2, for example, a third mask (not shown) having an opening is formed on the second mask 204, and the opening 205 is formed in the second mask 204 using this third mask. As shown in FIG. 3B, the bottom 206 of the opening 205 formed in the second mask 204 is in a state where the upper surface of the first mask 203 is exposed. Note that, in step S1, when the substrate 200 in which the opening 205 is formed in advance in the second mask 204 is provided as the processing target, step S2 is omitted.

[0018] When the top surface of the first mask 203 is exposed, the first mask 203 is selectively etched with respect to the second mask 204 to form an opening in the first mask 203, in which at least a part of the Space-CD (opening dimension) of the first mask 203 is larger than the Bottom CD of the second mask 204. By etching the first mask 203 in this manner so that at least a part of the Space-CD of the first mask 203 is larger than the Bottom CD of the second mask 204, even if deposits or the like adhere during etching of the etching target film 202, they are unlikely to be shaded, and the etching target film 202 directly below the first mask 203 can be vertically processed.

[0019] In one example, as shown in FIG. 3C, the first mask 203 is etched to the upper surface 207 of the etching target film 202 so that the side of the first mask 203 has an inverse tapered shape. That is, the first mask 203 is etched so that the CD of the bottom of the first mask 203, i.e., the bottom CD1 of the first mask 203, is larger than the CD of the bottom of the second mask 204, i.e., the bottom CD2 of the second mask 204. In this case, the first mask 203 may be anisotropically etched in the vertical direction until the etching target film 202 is exposed or immediately before it is exposed to form an opening, and then etched to widen the Space-CD of the opening. At this time, the first mask 203 may be etched by ion-modified ALE (Atomic layer etching) so as to widen the Space-CD of the opening formed in the first mask 203. In the ion-modified ALE, first, a part of the first mask 203 is modified by a first plasma generated from a first gas to form a modified region (step S3). Next, the modified region is removed by a second plasma generated from a second gas (step S4).

[0020] In another example, the first mask 203 is isotropically etched selectively with respect to the second mask 204 so that a recess is formed in a part of the sidewall of the first mask 203. For example, when the first mask 203 is a silicon-containing film or a metal-containing film, the first mask 203 can be etched by plasma generated from a fluorine-containing gas such as a fluorocarbon gas. Also, when the first mask 203 is an organic film, the first mask 203 can be etched by plasma generated from a hydrogen-containing gas or an oxygen-containing gas. In addition, the first mask 203 may be etched by adsorbing HF gas or the like on the substrate surface at a low temperature and reacting with the surface of the first mask 203, and then heating the substrate to a high temperature to desorb the HF gas after the reaction. HF gas can be used for etching both silicon-containing films and organic films. In addition to the above-mentioned gas adsorption method, HF gas can also be applied to a normal dry etching process. That is, the first mask 203 can be etched by using plasma generated from HF gas.

[0021] When the above-mentioned steps S3 and S4 are repeated to proceed with etching of the first mask 203 and the etching target film 202, the following process may be performed following step S4. That is, after removing the modified region of the first mask 203, a process may be performed in which a bottom CD1 of the first mask 203 and a bottom CD2 of the second mask 204 are compared, and whether or not the bottom CD1 is larger than the bottom CD2 is determined based on the comparison result.

[0022] If it is determined that the bottom CD1 is equal to or smaller than the bottom CD2, the process returns to step S3, and the ion-modified ALE of the first mask 203 is continued. On the other hand, if it is determined that the bottom CD1 is greater than the bottom CD2, it is determined whether the bottom CD1 is equal to or greater than a predetermined value. If it is determined that the bottom CD1 is less than the predetermined value, the process returns to step S3, and the ion-modified ALE of the first mask 203 is continued. On the other hand, if it is determined that the bottom CD1 is equal to or greater than the predetermined value, the etching target film 202 is etched.

[0023] Thereafter, a process may be performed to determine whether or not to end the etching of the etching target film 202. If the etching target film 202 has not been etched to the predetermined depth and the etching is not ended, the etching is continued. On the other hand, if the etching target film 202 has been etched to the predetermined depth, the etching is ended. As shown in FIG. 3D, the shape of the opening 205 is such that the etching is performed vertically to the vicinity of the bottom of the etching target film 202. In this way, by improving the vertical processability of the pattern formed on the substrate 200, shape abnormalities of the pattern can be suppressed.

[0024] [Membrane type] In this embodiment, the film types of the etching target film 202, the first mask 203, and the second mask 204 are not particularly limited. The base film 201 can be the substrate 200 itself, which is, for example, a silicon wafer. The etching target film 202 can be, for example, a silicon (Si) film, a germanium (Ge)-containing film, an organic film, or a metal-containing film. The organic film can be, for example, a carbon-containing film. The carbon-containing film may be formed of an amorphous carbon layer (ACL) or a spin-on carbon film (SOC). The metal-containing film can be, for example, a titanium (Ti) film, a tungsten (W) film, or the like. The etching target film 202 can be formed by stacking a plurality of types of films. For example, the etching target film 202 can be an ONON (silicon oxide film / silicon nitride film) film or an OPOP (silicon oxide film / polysilicon) film.

[0025] The first mask 203 may be any mask capable of selectively etching the etching target film 202. The second mask 204 may be any mask capable of selectively etching the first mask 203. For example, the first mask 203 may be a silicon-containing film, an organic film, or a metal-containing film. In this case, the second mask 204 may be any mask capable of selectively etching the first mask 203. More specifically, when a silicon-containing film is used as the first mask 203, the second mask 204 may be any mask capable of selectively etching the first mask 203. In addition, the silicon-containing film may be, for example, a silicon oxide film (SiO2 film), a silicon nitride film (SiN film), a silicon carbide film (SiC film), or a carbon-containing silicon oxide film (SiOC film). In one example, the first mask 203 may be a silicon nitride film, and the second mask 204 may be a silicon oxide film. In another example, the first mask 203 may be a silicon oxide film, and the second mask 204 may be a silicon nitride film. In yet another example, one of the first mask 203 and the second mask 204 may be a silicon film, and the other may be a film other than silicon. In addition, the first mask 203 may be an organic film, and the second mask 204 may be a silicon-containing film, or the first mask 203 may be a metal-containing film, and the second mask 204 may be a silicon-containing film or an organic film.

[0026] [Gas type for ion-modified ALE] In the ion-modified ALE of this embodiment, when the first mask 203 is a silicon-containing film or a metal film, for example, at least one selected from the group of He, hydrogen-containing gas, and nitrogen-containing gas can be used as the first gas, and a fluorine-containing gas can be used as the second gas. At least one selected from the group of H2 gas, D2 gas (deuterium gas), and NH3 gas may be used as the hydrogen-containing gas. At least one selected from the group of NF3 gas, SF6 gas, and fluorocarbon (e.g., CF4 gas) may be used as the fluorine-containing gas. The second gas may include an oxygen-containing gas. At least one selected from the group of O2 gas, CO2 gas, and CO gas may be used as the oxygen-containing gas. The second gas may further include a rare gas such as Ar.

[0027] In one example, when the first mask 203 is a silicon nitride film and the second mask 204 is a silicon oxide film, a hydrogen-containing gas can be used as the first gas and a fluorine-containing gas can be used as the second gas. In this case, the surface of the first mask 203 is irradiated with active hydrogen species by the first plasma generated from the first gas, and the vicinity of the surface is modified to become a modified region. This modified region is selectively etched and removed by active fluorine species in the second plasma generated from the second gas.

[0028] In another example, when the first mask 203 is a silicon oxide film and the second mask 204 is a titanium nitride film (TiN film), nitrogen (N2) gas is used as the first gas, and a mixed gas of NF3, O2, H2, and Ar or a mixed gas of CH3F, O2, H2, and Ar can be used as the second gas. In yet another example, when the first mask 203 is silicon carbide and the second mask 204 is a silicon nitride film, a germanium-containing film, a metal-containing film, or the like, a nitrogen-containing gas such as N2, NH3, NO, or NO2 is used as the first gas, and a fluorine-containing gas such as NF3, SF6, or CF4 is used as the second gas. In this case, a film containing titanium (Ti), tungsten (W), hafnium (Hf), zirconium (Zr), tantalum (Ta), or the like is used as the metal-containing film.

[0029] [Target pattern structure] FIG. 4 is a diagram showing an example of a pattern structure targeted in this embodiment. The substrate 200 shown in FIG. 4 shows a pattern structure targeted after etching of the etching target film 202. For the substrate 200 shown in FIG. 4, the relationship between the bottom CD211, which is the CD of the bottom of the second mask 204, the bottom CD212 of the first mask 203, and the bar CD213 of the etching target film 202 is bottom CD211>bottom CD212>bar CD213, which is the target. The bottom CD211, bottom CD212, and bar CD213 are Bar-CD. In other words, when expressed by Space-CD in FIG. 2 and FIG. 3, bottom CD2<bottom CD1.

[0030] [Experimental Results] Next, the bottom CD211, bottom CD212, and bar CD213 in the embodiment in which the etching target film 202 is a silicon film, the first mask 203 is a silicon nitride film, and the second mask 204 is a silicon oxide film will be described with reference to Fig. 5. The positions of the bottom CD211, bottom CD212, and bar CD213 are the same as those of the substrate 200 in Fig. 4. In Fig. 5, the case where a mask having a tapered sidewall at the bottom of the opening (for example, the mask 113 shown in Fig. 1B) is used will be described as Comparative Examples 1 and 2 in conjunction with the embodiment. The target value 215 of the bar CD213 is 40 nm.

[0031] Fig. 5 is a diagram showing an example of the experimental results of an example and a comparative example in this embodiment. As shown in Fig. 5, in the example, the bottom CD211 of the second mask 204 was 60 nm, the bottom CD212 of the first mask 203 was 48 nm, and the bar CD213 of the etching target film 202 was 47.5 nm. In other words, the relationship bottom CD211>bottom CD212>bar CD213 was achieved, which can improve the vertical processability of the pattern formed on the substrate 200 and suppress shape abnormalities of the pattern.

[0032] On the other hand, in Comparative Example 1, the bottom CD211 was 85 nm, the bottom CD212 was 50 nm, and the bar CD213 was 65 nm. In Comparative Example 1, the bar CD213 was larger than the bottom CD212, and the vertical processability of the pattern was reduced. In Comparative Example 2, the bottom CD211 was 73 nm, the bottom CD212 was 50 nm, and the bar CD213 was 57.5 nm. In Comparative Example 2, the bar CD213 was also larger than the bottom CD212, and the vertical processability of the pattern was reduced.

[0033] [Example of substrate processing equipment configuration] FIG. 6 is a diagram showing an example of a substrate processing apparatus according to the present embodiment. The substrate processing apparatus 10 shown in FIG. 6 can be used to realize the substrate processing method according to the embodiment. The substrate processing apparatus 10 shown in FIG. 6 is a so-called inductively-coupled plasma (ICP) apparatus, and has a plasma source for generating inductively-coupled plasma. However, the substrate processing apparatus according to the embodiment may use plasma generated by other methods. For example, the substrate processing apparatus according to the embodiment may be an apparatus that uses capacitively-coupled plasma (CCP), ECR plasma (electron-cyclotron-resonance plasma), helicon wave excited plasma (HWP), surface wave plasma (SWP), or the like.

[0034] The substrate processing apparatus 10 includes a chamber 12. The chamber 12 is made of a metal such as aluminum. The chamber 12 has, for example, a substantially cylindrical shape. The chamber 12 includes a space 12c in which processing is performed.

[0035] A substrate support 14 is disposed below the space 12c. The substrate support 14 is configured to hold a substrate W placed thereon. The substrate W is, for example, a substrate to be processed by the method of one embodiment.

[0036] The substrate support 14 can be supported by a support mechanism 13. The support mechanism 13 extends upward from the bottom of the chamber 12 within the space 12c. The support mechanism 13 may be substantially cylindrical. The support mechanism 13 may be made of an insulating material such as quartz.

[0037] The substrate support table 14 includes an electrostatic chuck 16 and a lower electrode 18. The lower electrode 18 includes a first plate 18a and a second plate 18b. The first plate 18a and the second plate 18b are made of a metal such as aluminum. The first plate 18a and the second plate 18b are, for example, substantially cylindrical. The second plate 18b is disposed on the first plate 18a. The second plate 18b is electrically connected to the first plate 18a.

[0038] The electrostatic chuck 16 is disposed on the second plate 18b. The electrostatic chuck 16 includes an insulating layer and a thin-film electrode disposed in the insulating layer. A DC power supply 22 is electrically connected to the thin-film electrode of the electrostatic chuck 16 via a switch 23. The electrostatic chuck 16 generates an electrostatic force from a DC voltage of the DC power supply 22. The electrostatic chuck 16 attracts and holds the substrate W by the generated electrostatic force.

[0039] During operation of the substrate processing apparatus 10, an edge ring FR is disposed on and around the second plate 18b so as to surround the outer periphery of the substrate W and the electrostatic chuck 16. The edge ring FR serves to improve process uniformity. The edge ring FR is made of, for example, silicon.

[0040] A flow path 24 is formed in the second plate 18b. A heat exchange medium such as a refrigerant is supplied to the flow path 24 from a temperature adjustment unit (e.g., a chiller unit) disposed outside the chamber 12 for temperature control. The temperature adjustment unit adjusts the temperature of the heat exchange medium. The heat exchange medium is supplied from the temperature adjustment unit to the flow path 24 through a pipe 26a. The heat exchange medium supplied from the temperature adjustment unit to the flow path 24 through the pipe 26a is then returned to the temperature adjustment unit through a pipe 26b. After the temperature adjustment by the temperature adjustment unit, the heat exchange medium is returned to the flow path 24 in the substrate support table 14. In this manner, the temperature of the substrate support table 14, i.e., the temperature of the substrate W, can be adjusted.

[0041] The substrate processing apparatus 10 further includes a gas supply line 28 that extends through the substrate support table 14 to the upper surface of the electrostatic chuck 16. A heat exchange gas, such as helium (He) gas, is supplied from a heat exchange gas supply mechanism through the gas supply line 28 to the space between the upper surface of the electrostatic chuck 16 and the lower surface of the substrate W. In this way, heat exchange between the substrate support table 14 and the substrate W is promoted.

[0042] Alternatively, a heater HT may be disposed in the substrate support table 14. The heater HT is a heating device. The heater HT is embedded in, for example, the second plate 18b or the electrostatic chuck 16. The heater HT is connected to a heater power supply HP. The heater power supply HP supplies power to the heater HT, thereby adjusting the temperature of the substrate support table 14 and, in turn, the temperature of the substrate W.

[0043] A radio frequency (RF) power supply 30 is connected to the lower electrode 18 of the substrate support table 14 via a matching box 32. An RF current can be supplied from the RF power supply 30 to the lower electrode 18. The RF power supply 30 generates RF power and attracts ions to the substrate W placed on the substrate support table 14. That is, the RF power supply 30 generates an RF current that serves as a bias voltage. The frequency of the RF current generated by the RF power supply 30 is within a range of, for example, 400 kilohertz to 40.68 megahertz. In one example, the frequency of the RF current is 13.56 megahertz.

[0044] The substrate processing apparatus 10 further includes a shield 34 detachably attached to the inner wall of the chamber 12. The shield 34 is also disposed so as to surround the outer periphery of the support mechanism 13. The shield 34 prevents by-products generated by the processing from adhering to the chamber 12. The shield 34 may be an aluminum member coated with a ceramic such as Y2O3.

[0045] An exhaust path is formed between the substrate support 14 and the side wall of the chamber 12. The exhaust path is connected to an exhaust port 12e formed at the bottom of the chamber 12. The exhaust port 12e is connected to an exhaust device 38 via a pipe 36. The exhaust device 38 includes a pressure adjustment unit and a vacuum pump such as a turbo molecular pump (TMP). A baffle plate 40 is disposed in the exhaust path, i.e., between the substrate support 14 and the side wall of the chamber 12. The baffle plate 40 has a plurality of through holes penetrating the baffle plate 40 in the thickness direction. The baffle plate 40 may be an aluminum member having a surface coated with ceramics such as Y2O3.

[0046] An opening is formed in the upper side of the chamber 12. The opening is closed by a window 42. The window 42 is made of a dielectric material such as quartz. The window 42 is, for example, a flat plate.

[0047] An intake port 12i is formed in the side wall of the chamber 12. The intake port 12i is connected to a gas supply unit 44 via a pipe 46. The gas supply unit 44 supplies various gases used in the process to the space 12c. The gas supply unit 44 includes a plurality of gas sources 44a, a plurality of flow controllers 44b, and a plurality of valves 44c. Although not shown in FIG. 6, a plurality of different intake ports may be provided for each gas to be supplied to prevent the gases from being mixed.

[0048] The multiple gas sources 44a include gas sources for various gases, which will be described later. One gas source may supply one or more gases. The multiple flow controllers 44b may be mass flow controllers (MFCs), and the flow controllers 44b realize flow rate control by pressure control. Each gas source included in the multiple gas sources 44a is connected to the intake port 12i via a corresponding one of the multiple flow controllers 44b and a corresponding one of the multiple valves 44c. The position of the intake port 12i is not particularly limited. For example, the intake port 12i may be formed in the window 42 instead of the sidewall of the chamber 12.

[0049] An opening 12p is formed in the sidewall of the chamber 12. The opening 12p serves as a path for the substrate W to be loaded into the space 12c of the chamber 12 from the outside and loaded from the space 12c to the outside of the chamber 12. A gate valve 48 is provided on the sidewall of the chamber 12, and is capable of opening and closing the opening 12p.

[0050] An antenna 50 and a shield 60 covering the antenna 50 are disposed on the chamber 12 and the window 42. The antenna 50 and the shield 60 are disposed outside the chamber 12 and above the window 42. In one embodiment, the antenna 50 includes an inner antenna element 52A and an outer antenna element 52B. The inner antenna element 52A is a spiral coil disposed in the center of the window 42. The outer antenna element 52B is a spiral coil disposed on the window 42 and on the outer periphery side of the inner antenna element 52A. The inner antenna element 52A and the outer antenna element 52B are each made of a conductive material such as copper, aluminum, stainless steel, or the like.

[0051] The inner antenna element 52A and the outer antenna element 52B are connected to an RF power source 70A and an RF power source 70B, respectively. The inner antenna element 52A and the outer antenna element 52B are supplied with power of the same or different frequencies from the RF power source 70A and the RF power source 70B, respectively. When RF power is supplied from the RF power source 70A to the antenna 50, an induction magnetic field is generated in the space 12c, which excites the processing gas in the space 12c to generate plasma above the substrate W.

[0052] The substrate processing apparatus 10 further includes a controller 80. The controller 80 may be a computing device including a processor, a storage unit such as a memory, an input unit, a display, and the like. The controller 80 operates based on a control program and recipe data stored in the storage unit, and controls each unit of the substrate processing apparatus 10. For example, the controller 80 controls the plurality of flow controllers 44b, the plurality of valves 44c, the exhaust device 38, the RF power sources 70A and 70B, the RF power source 30, the matching box 32, the heater power source HP, and the like. When implementing the substrate processing method according to the embodiment, the controller 80 may control each unit of the substrate processing apparatus 10 based on the control program and recipe data.

[0053] [effect] As described above, according to the present embodiment, the substrate processing method includes a) a step of providing a substrate 200 including an etching target film 202, a first mask 203 formed on the etching target film 202, and a second mask 204 formed on the first mask 203, the second mask 204 being of a different film type from the first mask 203, and having an opening, b) a step of selectively etching the first mask 203 with respect to the second mask 204 to form an opening in which at least a part of the opening dimension (bottom CD1) of the first mask 203 is larger than a bottom opening dimension (bottom CD2) of the second mask 204, and c) a step of etching the etching target film 202. As a result, the vertical processability of the pattern formed on the substrate 200 can be improved, and shape abnormalities of the pattern can be suppressed.

[0054] According to the present embodiment, in step b), the first mask is etched so that the opening dimension at the bottom of the first mask is larger than the opening dimension at the bottom of the second mask. As a result, the vertical processability of the pattern formed on the substrate 200 is improved, and shape abnormalities of the pattern can be suppressed.

[0055] Furthermore, according to this embodiment, the opening of the first mask has an inverse tapered shape, which results in improved vertical processability of the pattern formed on the substrate 200.

[0056] According to the present embodiment, the first mask is a silicon-containing film, an organic film, or a metal-containing film. As a result, the vertical processability of the pattern formed on the substrate 200 can be improved, and shape abnormalities of the pattern can be suppressed.

[0057] Moreover, according to this embodiment, the first mask 203 is a silicon-containing film, and the second mask 204 is a silicon-containing film, an organic film, or a metal-containing film different from the first mask 203. As a result, the first mask 203 can be etched into an inverse tapered shape.

[0058] Moreover, according to this embodiment, the first mask 203 is a silicon nitride film, a silicon oxide film, or a silicon carbide film, and the second mask 204 is a silicon-containing film different from the first mask. As a result, the first mask 203 can be etched into a reverse tapered shape.

[0059] According to the present embodiment, b) includes one or more steps of: b-1) forming a modified region by modifying a part of the first mask 203 with a first plasma generated from a first gas; and b-2) removing the modified region with a second plasma generated from a second gas. As a result, the first mask 203 can be etched into a reverse tapered shape by the ion modification ALE.

[0060] In addition, according to this embodiment, the first mask is a silicon-containing film or a metal-containing film, the first gas is a helium gas, a hydrogen-containing gas or a nitrogen-containing gas, and the second gas is a fluorine-containing gas. As a result, the first mask 203 can be etched into a reverse tapered shape by the ion-modified ALE.

[0061] According to the present embodiment, the hydrogen-containing gas is at least one selected from the group consisting of H2 gas, D2 gas, and NH3 gas, and the fluorine-containing gas is at least one selected from the group consisting of NF3 gas, SF6 gas, and fluorocarbon gas. As a result, the first mask 203 can be etched into a reverse tapered shape by the ion-modified ALE.

[0062] Moreover, according to this embodiment, the second gas further contains an oxygen-containing gas, so that the first mask 203 can be etched into a reverse tapered shape by the ion-modified ALE.

[0063] Moreover, according to this embodiment, the oxygen-containing gas is at least one selected from the group consisting of O2 gas, CO2 gas, and CO gas. As a result, the first mask 203 can be etched into a reverse tapered shape by the ion-modifying ALE.

[0064] According to the present embodiment, step b) is a step of isotropically etching the first mask using an etching gas, so that the first mask 203 can be etched into an inverted tapered shape.

[0065] According to the present embodiment, a) includes a-1) a step of providing a substrate having a film to be etched, a first mask, a second mask formed on the first mask and having a film type different from that of the first mask, and a third mask having an opening formed on the second mask, and a-2) a step of forming an opening in the second mask using the third mask. As a result, the vertical processability of the pattern formed on the substrate 200 can be improved, and shape abnormalities of the pattern can be suppressed.

[0066] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects, and may be omitted, substituted, or modified in various ways without departing from the spirit and scope of the appended claims.

[0067] In the above embodiment, the first mask 203 is etched by ion-modified ALE, but the present invention is not limited to this. For example, the first mask 203 may be etched into a reverse tapered shape by combining mask formation on a pattern by ALD (Atomic Layer Deposition), subconformal ALD, CVD (Chemical Vapor Deposition), or the like, and isotropic etching. [Explanation of symbols]

[0068] 10 Substrate processing equipment 200 Substrates 201 Base film 202 Film to be etched 203 First Mask 204 Second Mask 205 Aperture 206 Bottom 207 Top surface 211,212 Bottom CD 213 Bar CD

Claims

1. a) providing a substrate including a film to be etched, a first mask formed on the film to be etched, and a second mask formed on the first mask, the second mask having a film type different from that of the first mask and having an opening; b) selectively etching the first mask with respect to the second mask to form an opening having a bottom dimension of the first mask that is larger than a bottom dimension of the second mask and has an inverse tapered shape; c) etching the etching target film; A substrate processing method comprising the steps of:

2. The b) is b-1) modifying a portion of the first mask with a first plasma generated from a first gas to form a modified region; b-2) removing the modified region by a second plasma generated from a second gas; one or more times executing a sequence including The method for processing a substrate according to claim 1 .

3. The step b) is a step of isotropically etching the first mask using an etching gas. The method for processing a substrate according to claim 1 .

4. a) providing a substrate comprising a film to be etched, a first mask formed on the film to be etched, and a second mask formed on the first mask, the second mask being of a different film type than the first mask and having an opening; b) selectively etching the first mask with respect to the second mask to form an opening having a dimension at least in a portion of the first mask that is larger than a dimension at a bottom of the second mask; c) etching the etching target film; having The b) is b-1) modifying a portion of the first mask with a first plasma generated from a first gas to form a modified region; b-2) removing the modified region by a second plasma generated from a second gas; one or more times executing a sequence including A method for processing a substrate.

5. The step b) includes etching the first mask so that a dimension of an opening at a bottom of the first mask is larger than a dimension of an opening at a bottom of the second mask. The substrate processing method according to claim 4 .

6. the opening of the first mask has an inverted tapered shape; The substrate processing method according to claim 5 .

7. the first mask is a silicon-containing film or a metal-containing film; the first gas is helium gas, a hydrogen-containing gas, or a nitrogen-containing gas; The second gas is a fluorine-containing gas.

7. The substrate processing method according to claim 2, wherein the substrate is heated to a temperature of 100.degree.

8. The first mask is a silicon-containing film, an organic film, or a metal-containing film. The substrate processing method according to any one of claims 1 to 6.

9. the first mask is a silicon-containing film or a metal-containing film; The second mask is a silicon-containing film, an organic film, or a metal-containing film different from the first mask. The substrate processing method according to any one of claims 1 to 7.

10. the first mask is a silicon nitride film, a silicon oxide film, a silicon carbide film, or a metal-containing film; the second mask is a silicon-containing film different from the first mask; The substrate processing method according to any one of claims 1 to 7.

11. The hydrogen-containing gas is at least one selected from the group consisting of H2 gas, D2 gas, and NH3 gas, The fluorine-containing gas is at least one selected from the group consisting of NF3 gas, SF6 gas, and fluorocarbon gas. The substrate processing method according to claim 7 .

12. The second gas further comprises an oxygen-containing gas. The substrate processing method according to any one of claims 2, 4 to 7, and 11.

13. The oxygen-containing gas is at least one selected from the group consisting of O2 gas, CO2 gas and CO gas. The method of claim 12.

14. The a) is a-1) providing a substrate having the etching target film, the first mask, a second mask formed on the first mask and having a film type different from that of the first mask, and a third mask having an opening formed on the second mask; a-2) forming the opening in the second mask using the third mask; The substrate processing method according to any one of claims 1 to 13.

15. A substrate processing apparatus, comprising: A chamber; a substrate support provided inside the chamber; an intake port for receiving a supply of a process gas into the interior of the chamber; A plasma generating unit; A control unit, the control unit is configured to control the substrate processing apparatus to provide a substrate including: a) a film to be etched; a first mask formed on the film to be etched; and a second mask formed on the first mask, the second mask having a film type different from that of the first mask and having an opening; the control unit is configured to control the substrate processing apparatus to selectively etch the first mask with respect to the second mask, so that an opening dimension of a bottom portion of the first mask is larger than an opening dimension of a bottom portion of the second mask and has an inverse tapered shape; The control unit is configured to c) control the substrate processing apparatus to etch the etching target film. Substrate processing equipment.

16. A substrate processing apparatus comprising: A chamber; a substrate support provided inside the chamber; an intake port for receiving a supply of a process gas into the interior of the chamber; A plasma generating unit; A control unit, the control unit is configured to control the substrate processing apparatus to provide a substrate including: a) a film to be etched; a first mask formed on the film to be etched; and a second mask formed on the first mask, the second mask having a film type different from that of the first mask and having an opening; the control unit is configured to control the substrate processing apparatus to selectively etch the first mask with respect to the second mask to form an opening having a dimension larger than a dimension of an opening at a bottom of the second mask at least in a portion of the first mask; The control unit is configured to c) control the substrate processing apparatus to etch the etching target film; The control unit, as the b), the control unit is configured to control the substrate processing apparatus so as to: b-1) modify a part of the first mask by a first plasma generated from a first gas to form a modified region; the control unit is configured to control the substrate processing apparatus so as to remove the modified region by a second plasma generated from a second gas; The control unit is configured to control the substrate processing apparatus to execute a sequence including the steps b-1) and b-2) at least once. Substrate processing equipment.

Images