Pattern forming method

Abstract

This pattern forming method includes steps (a)–(f). In step (a), a substrate is prepared, the substrate comprising a core that has a side surface and an upper surface, and a mask that is provided on the upper surface of the core and has a side surface that is continuous with the side surface of the core. In step (b), a recess is formed by etching the side surface of the core so that at least a portion of the side surface of the core is positioned on the inside of the side surface of the mask. In step (c), a sacrificial film is buried in a recess that is formed by the core, the mask, and the substrate. In step (d), an encapsulating film is formed, the encapsulating film having a first portion that covers the sacrificial film that is formed in the recess, a second portion that is continuous with the first portion and covers the mask, and a third portion that is continuous with the first portion and extends over the substrate. In step (e), the sacrificial film is removed. In step (f), the second portion and the third portion of the encapsulating film are removed by etching.

Description

Pattern Formation Method

[0001] The present disclosure relates to a patterning method.

[0002] For example, Patent Document 1 discloses a "method for forming a fine pattern of a semiconductor device using a fine-pitch hard pattern formed by a double patterning process."

[0003] Patent No. 5492381

[0004] The present disclosure provides a pattern formation method that contributes to improving productivity and miniaturization in semiconductor patterning processes.

[0005] In one aspect of the present disclosure, a pattern formation method includes steps (a) to (f). In step (a), a substrate is prepared, including a core material having a side surface and a top surface, and a mask material provided on the top surface of the core material and having a side surface continuous with the side surface of the core material. In step (b), a recess is formed by etching the side surface of the core material so that at least a portion of the side surface of the core material is located inside the side surface of the mask material. In step (c), a sacrificial film is embedded in the recess formed by the core material, the mask material, and the substrate. In step (d), a sealing film is formed, including a first portion covering the sacrificial film formed in the recess, a second portion covering the mask material in a continuous manner with the first portion, and a third portion extending on the substrate in a continuous manner with the first portion. In step (e), the sacrificial film is removed. In step (f), the second and third portions of the sealing film are removed by etching.

[0006] According to the present disclosure, it is possible to provide a pattern formation method that contributes to improving the productivity and miniaturization of semiconductor patterning processes.

[0007] FIG. 1 is a flowchart showing an example of a pattern formation method according to the first embodiment. FIG. 2A is a diagram showing an example of a pattern formation process. FIG. 2B is a diagram showing an example of a pattern formation process. FIG. 2C is a diagram showing an example of a pattern formation process. FIG. 2D is a diagram showing an example of a pattern formation process. FIG. 2E is a diagram showing an example of a pattern formation process. FIG. 2F is a diagram showing an example of a pattern formation process. FIG. 2G is a diagram showing an example of a pattern formation process. FIG. 2H is a diagram showing an example of a pattern formation process. FIG. 2I is a diagram showing an example of a pattern formation process. FIG. 2J is a diagram showing an example of a pattern formation process. FIG. 3 is a diagram showing polymerization and depolymerization of a polymer. FIG. 4 is a flowchart showing an example of a pattern formation method according to the second embodiment. FIG. 5A is a diagram showing an example of a pattern formation process. FIG. 5B is a diagram showing an example of a pattern formation process. FIG. 5C is a diagram showing an example of a pattern formation process. FIG. 6 is a diagram showing an example of an apparatus.

[0008] Hereinafter, embodiments of the disclosed pattern formation method will be described in detail with reference to the drawings. Note that the pattern formation method according to the present disclosure is not limited to these embodiments, and the following embodiments can be appropriately combined within the scope of the present disclosure, so long as they do not cause any contradiction between the configurations and processing contents of the present disclosure.

[0009] The drawings referred to below are schematic for the sake of convenience. Therefore, details may be omitted, and the dimensional ratios do not necessarily correspond to the actual ones. In addition, in the drawings referred to below, the vertically upward direction is defined as the Z-axis direction for ease of understanding.

[0010] Furthermore, an embodiment of the disclosed pattern formation method is a method for forming a pattern on a substrate, and is performed by an apparatus having a chamber and performing substrate processing such as plasma processing or heat treatment. The apparatus is controlled by a control unit connected to the apparatus. The apparatus shown below refers to any of a plurality of apparatuses including a film formation apparatus, an etching apparatus, and an annealing apparatus. Substrates can be automatically transported between the plurality of apparatuses in a vacuum or air atmosphere using a transport device.

[0011] First Embodiment [Pattern Forming Method] A pattern forming method according to a first embodiment of the present disclosure will be described with reference to Fig. 1 and Fig. 2A to Fig. 2J. Fig. 1 is a flowchart showing an example of the pattern forming method according to the first embodiment. Fig. 2A to Fig. 2J are diagrams showing an example of a pattern formation process.

[0012] (Preparation of Substrate: S100) The apparatus prepares in a chamber a substrate W (step S100) that includes a core material 13 having a side surface and a top surface, and a mask material 14 that is provided on the top surface of the core material 13 and has a side surface that is continuous with the side surface of the core material 13. Step S100 is an example of the process (a).

[0013] In step S100, for example, as shown in FIG. 2A, a substrate W having a plurality of mask materials 14 stacked on a plurality of core materials 13 is carried into a chamber. For example, the plurality of core materials 13 may be made of silicon oxide (SiO ２ The plurality of mask materials 14 may be silicon nitride (SiN) films.

[0014] The patterns of the multiple core materials 13 and the multiple mask materials 14 may be transferred by using a resist film (not shown) as a mask. As an example of transferring the pattern of the resist film, an exposure process is performed on a photoresist coated on the multiple mask materials 14 using an exposure device (not shown). The light source used in the exposure device may be an ArF light source or a KrF light source. After exposure, a development process is performed using a development device (not shown), and the pattern of the resist film is formed. The stacked film of a silicon nitride film and a silicon oxide film underlying the resist film is etched to form the multiple core materials 13 and the multiple mask materials 14 to which the pattern of the resist film has been transferred. The multiple core materials 13 and the multiple mask materials 14 may be arranged in a line-and-space (line / space) configuration with a pitch P as illustrated in FIG. 2A .

[0015] The substrate W includes a silicon substrate 10, a first film 11, and a second film 12 stacked in this order, with a plurality of core materials 13 and a plurality of mask materials 14 stacked on the second film 12. For example, the first film 11 may be a polysilicon film or a titanium nitride film. For example, the second film 12 may be any film that has a selectivity relative to the core material 13 during etching, in other words, a film that is less likely to be scraped than the core material 13, and may be, for example, a carbon film or a silicon nitride film. This results in the silicon substrate 10, the first film 11, the second film 12, the plurality of core materials 13, and the plurality of mask materials 14 stacked in this order. For ease of explanation, the stacking direction of the plurality of core materials 13 and the plurality of mask materials 14 is referred to as the Z direction in this specification.

[0016] (Isotropic Etching: S101) Next, the device etches the side surface of the core material 13 to form a recess so that at least a portion of the side surface of the core material 13 is located inside the side surface of the mask material 14 (step S101). Step S101 is an example of process (b). The etching in step S101 may be isotropic etching.

[0017] In step S101, the apparatus supplies an etching gas into the chamber, which has a higher etching rate for the core material 13 than for the mask material 14 and promotes isotropic etching, to generate plasma. Then, isotropic etching is performed, mainly by radicals from the generated plasma, and the side surfaces of the multiple core materials 13 are removed further inward than the side surfaces of the multiple mask materials 14. As a result, as shown in FIG. 2B , in a cross-sectional view, the side surfaces of the core material 13 are removed more than the side surfaces of the mask material 14, making the core material 13 thinner in a direction perpendicular to the Z direction than the mask material 14. As a result, in a cross-sectional view, the core material 13 and the mask material 14 form a structure having a lateral shape in which the mask material 14 is provided above the core material 13. As a result, recesses 60 are formed on both side surfaces of the multiple core materials 13, and spaces are expanded on both side surfaces of the multiple core materials 13. In other words, the recesses 60 are formed by the core material 13, the mask material 14, and the substrate (second film 12). The isotropic etching is not limited to dry etching using plasma of an etching gas, but may be wet etching using an etching solution.

[0018] (Transporting the Substrate: S102) Next, the apparatus unloads the substrate W from the chamber where the processing in step S101 has been performed, and transports it into a chamber where the processing in the next step S103 will be performed (step S102).

[0019] (Filling of Sacrificial Film: S103) Next, the apparatus fills the recess 60 with the sacrificial film 15 (step S103). Step S103 is an example of process (c). The apparatus may fill the recess 60 with the sacrificial film 15 by polymerizing multiple types of monomers.

[0020] For example, in step S103, a first monomer and a second monomer are supplied into the chamber as multiple types of monomers. A vapor deposition polymerization reaction between the first monomer and the second monomer occurs, thereby filling the recess 60 of the substrate W with a polymer material. The polymer material is an example of the sacrificial film 15. In this embodiment, the first monomer may be, for example, an isocyanate, and the second monomer may be, for example, an amine. The polymer material may be polyurea. As a result, the sacrificial film 15 is filled in the recess 60 formed on both side surfaces of the core material 13, as shown in FIG. 2C . The sacrificial film 15 may also be formed on the side surfaces and top surface of the mask material 14, the top surface of the second film 12, and the like.

[0021] FIG. 3 illustrates the polymerization and depolymerization of a polymer. For example, FIG. 3(1) illustrates an isocyanate. FIG. 3(2) illustrates an amine. The isocyanate and the amine undergo a vapor deposition polymerization reaction (FIG. 3(x)) to form a polymer material containing a urea bond, as shown in FIG. 3(3). The isocyanate is an example of a first monomer. The amine is an example of a second monomer. The polymer material is a polymer and an example of a sacrificial film 15. Note that the "R" connected to the urea bond shown in FIG. 3(3) is, for example, an alkyl group (linear alkyl group or cyclic alkyl group) or an aryl group, and n is an integer of 2 or greater. The "R"s shown in FIGS. 3(1) and 3(2) are also alkyl groups or aryl groups.

[0022] As the isocyanate, for example, an alicyclic compound, an aliphatic compound, an aromatic compound, or the like can be used. An example of the alicyclic compound is 1,3-bis(isocyanatomethyl)cyclohexane (H6XDI), and an example of the aliphatic compound is hexamethylene diisocyanate. As the amine, for example, an alicyclic compound, an aliphatic compound, an aromatic compound, or the like can be used. An example of the alicyclic compound is 1,3-bis(aminomethyl)cyclohexane (H6XDA), and an example of the aliphatic compound is hexamethylene diisocyanate. The compound may have three or more amino groups, and may also be a secondary amine in which the hydrogen of the amino group is substituted.

[0023] In step S103, the sacrificial film 15 is buried in the recess 60 under the following processing conditions, for example. The temperature of the substrate W may be the temperature of the stage on which the substrate W is placed. Pressure inside the chamber: 0.5 to 20 Torr (66.7 to 2666 Pa) Flow rate of isocyanate vapor: 1 to 20 sccm (0.0017 to 0.034 Pa·m ３ / s) Flow rate of amine vapor: 1 to 20 sccm (0.0017 to 0.034 Pa m ３ / s) Temperature of substrate W: 40 to 150°C

[0024] However, the sacrificial film 15 is not limited to a polymer material containing urea bonds, and may be a carbon film, a carbon-containing film, or other film.

[0025] (Transporting the Substrate: S104) Next, the apparatus unloads the substrate W from the chamber where the processing in step S103 has been performed, and transports it into a chamber where the processing in the next step S105 will be performed (step S104).

[0026] (Removal of Unnecessary Sacrificial Film: S105) Next, the apparatus removes the unnecessary sacrificial film 15 on the substrate W (step S105). In step S105, plasma is generated from a processing gas for removing the unnecessary sacrificial film 15 in the chamber. The processing gas is, for example, a mixed gas of hydrogen gas and nitrogen gas. Then, the generated plasma removes the unnecessary sacrificial film 15 formed on the side and upper surface of the mask material 14 and the upper surface of the second film 12, as shown in FIG. 2D , for example.

[0027] In step S105, the unnecessary sacrificial film 15 is removed, for example, under the following processing conditions. The temperature of the substrate W may be the temperature of the stage on which the substrate W is placed. Pressure in the chamber: 0.05 to 1.0 Torr (6.67 to 133 Pa) Processing gas: H ２ / N ２ Gas: 100 to 300 sccm / 100 to 300 sccm (0.17 to 0.51 Pa m ３ / s / 0.17~0.51Pa・m ３ / s) High frequency power: 100 to 400 W Temperature of substrate W: 40 to 200°C

[0028] If the device to which the substrate W was transported in step S104 cannot perform the film formation process in step S106, the substrate W is transported to an device that can perform the film formation process in step S106 after the processing in step S105 is performed.

[0029] (Deposition of Sealing Film: S106) Next, the apparatus deposits a sealing film covering the sacrificial film 15 (step S106). Step S106 is an example of process (d). In step S106, plasma is generated in the chamber from a process gas such as organic aminosilane. The generated plasma then forms a conformal sealing film 16 covering the sacrificial film 15, the mask material 14, and the second film 12, as shown in FIG. 2E, for example. The sealing film 16 has a first portion 16a covering the sacrificial film 15 formed in the recess 60, a second portion 16b continuing from the first portion 16a and covering the mask material 14, and a third portion 16c continuing from the first portion 16a and extending onto the substrate (second film 12). The apparatus may deposit the sealing film 16 using the same material as the multiple core materials 13. The sealing film 16 may be, for example, a silicon oxide film made of the same material as the multiple core materials 13. The sealing film 16 is not limited to this, and may be made of a material different from that of the core material. For example, the sealing film 16 may be a silicon-containing film such as a silicon nitride film.

[0030] In step S106, the sealing film 16 is formed under the following processing conditions, for example. The temperature of the substrate W may be the temperature of the stage on which the substrate W is placed. Pressure inside the chamber: 0.1 to 10 Torr (13.3 to 1333 Pa) Processing gas: organic aminosilane gas; 10 to 50 sccm (0.017 to 0.085 Pa·m ３ / s) High frequency power: 50 to 200 W Temperature of substrate W: 20 to 200°C

[0031] (Transporting the Substrate: S107) Next, the apparatus transports the substrate W having the sacrificial film 15 and the sealing film 16 (step S107). In step S107, the substrate W is unloaded from the chamber in which the process of step S106 was performed, and is transported into a chamber in which the process of the next step S108 is performed.

[0032] (Removal of Sacrificial Film: S108) Next, the apparatus heats the substrate W to remove the sacrificial film 15 (step S108). Step S108 is an example of process (e). In step S108, the apparatus heats the substrate W to a temperature at which the sacrificial film 15 is thermally decomposed. The apparatus heats the substrate W to a temperature of, for example, 400° C. or higher. The temperature of the substrate W may be the temperature of a stage on which the substrate W is placed.

[0033] Furthermore, the step (e) of removing the sacrificial film 15 may be combined with a treatment using plasma. The apparatus heats the substrate W and assists the thermal decomposition of the sacrificial film 15 with plasma, thereby removing the sacrificial film 15 in the recess 60. This allows the temperature at which the substrate W is heated to be lowered.

[0034] As a result, the device decomposes the sacrificial film 15 by depolymerization as shown in Fig. 3(y) and detaches the sacrificial film 15 via the sealing film 16. As a result, the sacrificial film 15 in the recess 60 is removed by depolymerization, as shown in Fig. 2F, for example. As a result, an air gap 17 is formed in the recess 60.

[0035] The sealing film 16 located on the side surface of the recess 60 undergoes film contraction when the substrate W is heated, the sacrificial film 15 is removed by depolymerization to form the air gap 17, and the volume of the air gap 17 expands. Then, by cooling, the thin film surface of the sealing film 16 located on the side surface shrinks. The film surface that has undergone film contraction has the property of maintaining a non-distorted shape, and the shape of the film generated on the pattern becomes easily changeable.

[0036] In addition, air gaps 17 formed from materials such as polyurethane produced by the vapor deposition polymerization reaction of isocyanate and alcohol, or polymer materials containing polyurea produced by the vapor deposition polymerization reaction of multiple types of monomer materials (such as isocyanate and amine) with a molecular weight of 200 or less, similarly expand in volume. Subsequent cooling causes the thin film surface of the sealing film 16 located on the side to shrink. The film surface that has undergone film shrinkage has the property of maintaining a non-distorted shape, making it easier to change the shape of the film formed on the pattern. Furthermore, because the volume expansion due to depolymerization is not affected by pressure, atmospheric pressure can also be removed. Meanwhile, this phenomenon in pattern formation is not limited to depolymerization; a similar phenomenon occurs in the process of cooling after a plasma etching process involving substrate heating. Therefore, the shape of the film formed on the pattern is also easier to change in the process of pattern formation using a plasma etching process.

[0037] Here, if the sealing film 16 is too thick, the thermally decomposed sacrificial film 15 may not be able to pass through the sealing film 16 and may remain as residue in the recess 60. Therefore, the thickness of the sealing film 16 is controlled in step S106 so that the sacrificial film 15 can be detached through the sealing film 16 in step S108. This allows the device to prevent residue from being generated in the recess 60 in step S108.

[0038] (Transporting the Substrate: S109) The apparatus transports the substrate W (step S109). In step S109, the substrate W is unloaded from the chamber where the process of step S108 was performed, and is transported into a chamber where the process of the next step S110 is performed.

[0039] (Changing the Shape of the Sealing Film: S110) Next, the apparatus forms a sealing film 16 and changes the shape of the sealing film 16 (step S110). Step S110 is an example of process (g). In step S110, the apparatus may generate plasma from a process gas such as organic aminosilane in a chamber. The apparatus may increase the thickness of the sealing film 16 by mainly using a precursor of the generated plasma so that the width of the sealing film 16 becomes the same as the width of the core material 13. In step S110, the apparatus may form a film made of the same material as the sealing film 16 formed in step S106. Furthermore, if the width (thickness) or the shape of the side of the core material 13 is different, the shape may be further adjusted by etching or the like. As a result, the width of the sealing film 16 may become the same as the width of the core material 13, as shown in FIG. 2G, for example.

[0040] However, the process of step S110 may be omitted. For example, if the width of sealing film 16 that seals air gap 17 is the same as the width of core material 13, the apparatus may omit the process of step S110.

[0041] (Anisotropic Etching: S111) Next, the device removes the second portion 16b and the third portion 16c of the sealing film 16 by etching (step S111). Step S111 is an example of process (f). The etching in step S111 may be anisotropic etching.

[0042] In step S111, the apparatus supplies an etching gas that accelerates etching in the Z direction more than etching in a direction perpendicular to the Z direction into the chamber, and generates plasma. Anisotropic etching is then performed, mainly by ions of the generated plasma, to remove the second portion 16 b and the third portion 16 c of the sealing film 16. As a result, as shown in FIG. 2H , the second portion 16 b and the third portion 16 c of the sealing film 16 are removed, and the first portion 16 a of the sealing film 16 remains parallel to the core material 13.

[0043] (Removal of Mask Material: S112) Next, the apparatus removes the mask material 14 by etching (step S112). Step S112 is an example of the process (f).

[0044] In step S112, the apparatus supplies an etching gas capable of selectively removing the mask material 14 into the chamber and generates plasma. The generated plasma then removes the mask material 14. However, if the apparatus can remove the mask material 14 without using plasma, the mask material 14 may be removed by a method that does not use plasma. As a result, as illustrated in FIG. 2I, the mask material 14 is removed, leaving behind the first portion 16a of the sealing film 16 (hereinafter also referred to as the "sealing film 16a") and the core material 13.

[0045] (Transporting the Substrate: S113) Next, the apparatus transports the substrate W from the chamber in which the process of step S112 has been performed into a chamber in which the process of the next step S114 will be performed (step S113).

[0046] (Etching of Etching Target Film: S114) Next, the device etches the etching target film (step S114). In step S114, a gas for etching the etching target film is supplied into the chamber, and plasma is generated. The generated plasma then etches the etching target film located below the core material 13 and the sealing film 16a into the pattern of the core material 13 and the sealing film 16a. For example, as shown in FIG. 2J, the core material 13 and the sealing film 16a are used as a mask to etch the second film 12 into the pattern of the core material 13 and the sealing film 16a.

[0047] (Repetition Determination: S115) Next, the device determines whether the processing of steps S100 to S114 has been repeated a set number of times (step S115). The set number of times is a predetermined value equal to or greater than 1. If the device determines that the processing of steps S100 to S114 has not been repeated the set number of times, it returns to step S100 and repeats the processing of steps S100 to S114 until the set number of times has been reached.

[0048] (Unloading the Substrate: S116) When the apparatus determines in step S115 that the processes of steps S100 to S114 have been repeated the set number of times, it unloads the substrate W from the chamber in which step S114 was performed (step S116). This completes the pattern formation method according to the first embodiment. The example in FIG. 2J shows the result when the set number of repetitions in step S115 is set to 1. A pattern with a pitch that is 1 / 3 the pitch P of the core material 13 is transferred to the second film 12. When the set number of repetitions in step S115 is set to 2, the process returns to step S100, and in step S101, the second film 12 and the first film 11 are formed into a structure having a lateral shape. Thereafter, steps S102 to S115 are performed, whereby a pattern with a pitch that is 1 / 3 the pitch P of the first film 11 is transferred to the film (not shown) below the first film 11 in FIG. 2J. As a result, a pattern with a pitch that is 1 / 9 of the pitch P of the core material 13 is formed on the lower film of the first film 11. When the number of repetitions set in the process of S115 is set to 3, a pattern with a pitch that is 1 / 27 of the pitch P of the core material 13 is formed. When the number of repetitions set in the process of S115 is set to m, a pattern with a pitch that is 1 / 3 of the pitch P of the core material 13 is formed. ｍ ) pitch pattern is formed.

[0049] [Effects] The first embodiment provides a pattern formation method that enables patterning from air gap formation by depolymerization or air gap formation using depolymerization and plasma or thermal energy. As a result, the device forms a number of patterns for n (n is a number equal to or greater than 1) mandrels 13, the least common multiple of which is three times n. This allows for a dramatic increase in the number of semiconductor elements that can be formed, and allows for pattern formation even in patterns with narrower gaps, in order to contribute to productivity and miniaturization in the semiconductor patterning process. Specifically, the device executes the processes of steps S100 to S114 m (m is a number equal to or greater than 1) times to form (n×3) patterns for n mandrels 13. ｍ) patterns are formed. m is the set number of repetitions. When m is 1, (n × 3) mask patterns are formed for n mandrels 13. For example, when m is 1, nine mask patterns are formed by the mandrels 13 and sealing film 16a in FIG. 2I for the three mandrels 13 shown in FIG. 2A. In other words, the pitch of the formed mask patterns is P / 3, which is one-third of the pitch P of the mandrels 13. This allows the device to transfer a pattern with a pitch that is one-third of the pitch P of the mandrels 13 to the film to be etched.

[0050] For example, in the case of single patterning, a pattern having the same pitch as the pitch P of the core material 13 is transferred onto the film to be etched. In addition, in the case of double patterning, as described in, for example, Japanese Patent No. 5492381, patterns are formed in the number of which the least common multiple is twice n. In the case of double patterning, when the set number of repetitions increases to 1, 2, 3, ..., m, patterns having the same pitch as the pitch P of the core material 13 are formed onto the film to be etched. ｍ ) pitch pattern is transferred.

[0051] In contrast to this, according to the pattern forming method of the first embodiment, patterns are formed in a number whose least common multiple is three times n. Patterning in which patterns whose least common multiple is three times n are formed is also called "triple patterning." In the case of triple patterning, when the set number of repetitions increases to 1, 2, 3, ..., m, patterns whose least common multiple is three times n are formed in the etching target film in a number whose least common multiple is three times n. ｍ ) pitch pattern is transferred.

[0052] Compared to single patterning and double patterning, triple patterning can dramatically improve productivity and miniaturization in semiconductor patterning processes. For example, when the set number of repetitions is 1, triple patterning enables microfabrication that is three times and 1.5 times finer than single patterning and double patterning, respectively, without increasing the number of processes. This allows the pitch to be reduced to one-third that of single patterning. This contributes to productivity and miniaturization in semiconductor patterning processes, dramatically improving productivity.

[0053] In the first embodiment, when the sacrificial film 15 is thermally decomposed by the pattern formation method, the polymer material is decomposed into monomers by depolymerization, and the gasified monomers are released through the sealing film 16a. At this time, the sealing film 16a is pushed outward. As a result, triple patterning is realized by taking advantage of the phenomenon that the sealing film 16a covering the recess 60 stretches in the Z direction. The sealing film 16a stretched in the Z direction is formed on the left and right sides of the core material 13, sandwiching the air gap 17 therebetween, and is formed into the same pattern as the core material 13 by further increasing its thickness through film formation or by etching to adjust its shape. As a result, the pitch of the mask pattern formed from the core material 13 and the sealing film 16a becomes 1 / 3 of the pitch of the core material 13. Furthermore, when the set number of repetitions is m or more, in triple patterning, the pitch of the mask pattern becomes 1 / (3 ｍ Therefore, triple patterning achieves a fine pattern with a mask pattern pitch of 1 / (2 ｍ ) the fine patterns, it contributes to the productivity and miniaturization of the semiconductor patterning process, and results in a significant reduction in the number of processes.

[0054] From the above, triple patterning enables finer processing than single patterning and double patterning, and dramatically contributes to the productivity and miniaturization of the semiconductor patterning process on the substrate, thereby increasing productivity and reducing device manufacturing costs.

[0055] Furthermore, in the pattern formation method according to the first embodiment, even if an ArF light source or a KrF light source is used for the exposure process, fine processing equivalent to fine patterning using an EUV (Extreme Ultraviolet) light source, which uses extreme ultraviolet light for exposure, is possible. This allows for a reduction in process costs. Furthermore, by applying the pattern formation method according to the first embodiment to patterning using an EUV light source, fine patterns that could not be achieved by double patterning can be formed. This allows for a reduction in the area of ​​each semiconductor element on a substrate, thereby reducing the cost of manufacturing devices.

[0056] Furthermore, in contrast to the pattern formation method according to the first embodiment, the polyurea film can also be used in pattern formation using a coating process. In the coating process, the coating film completely fills the lateral shape, so it is necessary to form multiple mask materials 14 on the pattern and then leave a film on top of the lateral shape. However, by filling the recesses 60 with a polymer material containing polyurea produced by the vapor deposition polymerization reaction of multiple types of monomer materials in the sacrificial film 15 to form an air gap, it is possible to fill only the pattern having the lateral shape. This allows the conformal shape of the sealing film 16 to be maintained. Furthermore, the coating film, multiple mask materials 14, and sealing film 16 can be removed in a short etching time.

[0057] Second Embodiment [Pattern Forming Method] A pattern forming method according to a second embodiment of the present disclosure will be described with reference to Fig. 4, Figs. 2A to 2D, and Figs. 5A to 5C. Fig. 4 is a flowchart showing an example of the pattern forming method according to the second embodiment. Figs. 2A to 2D and Figs. 5A to 5C are diagrams showing an example of the pattern forming process. Note that the silicon substrate 10 and the first film 11 are omitted from Figs. 5A to 5C.

[0058] (Preparation of Substrate: S200) The apparatus prepares in a chamber a substrate (step S200) that includes a core material 13 having a side surface and a top surface, and a mask material 14 that is provided on the top surface of the core material 13 and has a side surface that is continuous with the side surface of the core material 13. Step S200 is an example of the process (a).

[0059] In step S200, as shown in FIG. 2A, a substrate W having a plurality of mask materials 14 stacked on a plurality of core materials 13 is loaded into a chamber. For example, the plurality of core materials 13 may be made of silicon oxide (SiO ２ ), and the plurality of mask materials 14 may be silicon nitride (SiN) films.

[0060] The method described in the process of step S100 can be used to form the patterns of the multiple core materials 13 and the multiple mask materials 14. The multiple core materials 13 and the multiple mask materials 14 thus formed may be line-and-space patterns arranged at a pitch P.

[0061] (Isotropic Etching: S201) Next, the apparatus etches the side surfaces of the core material 13 to form recesses so that at least a portion of the side surfaces of the core material 13 is positioned more inward than the side surfaces of the mask material 14 (step S201). Step S201 is an example of process (b). The etching in step S201 may be isotropic etching. The process of step S201 can employ the method described for the process of step S101. As a result, as shown in FIG. 2B , for example, in a cross-sectional view, the side surfaces of the core material 13 are shaved more than the side surfaces of the mask material 14, making the core material 13 thinner than the mask material 14 in a direction perpendicular to the Z direction. As a result, in a cross-sectional view, the core material 13 and the mask material 14 form a structure having a lateral shape in which the mask material 14 is provided on top of the core material 13. As a result, recesses 60 are formed on both side surfaces of the multiple core materials 13, and space is expanded on both side surfaces of the multiple core materials 13. The isotropic etching is not limited to dry etching using plasma of an etching gas, but may be wet etching using an etching solution.

[0062] (Transporting the Substrate: S202) Next, the apparatus unloads the substrate W from the chamber where the process of step S201 has been performed, and transports it into a chamber where the process of the next step S203 will be performed (step S202).

[0063] (Embedding of Sacrificial Film: S203) Next, the apparatus embeds the sacrificial film 15 in the recess 60 (step S203). Step S203 is an example of process (c). The apparatus may supply a film formation gas containing carbon into the chamber and embed a carbon film as the sacrificial film 15 in the recess 60. As a result, as shown in FIG. 2C , for example, the sacrificial film 15 is embedded in the recess 60 on both sides of the side surface of the core material 13. However, the sacrificial film 15 is not limited to a carbon film and may be a carbon-containing film or other film.

[0064] (Transporting the Substrate: S204) Next, the apparatus unloads the substrate W from the chamber where the process of step S203 has been executed, and transports it into a chamber where the process of the next step S205 will be executed (step S204).

[0065] (Removal of Unnecessary Sacrificial Film: S205) Next, the apparatus removes the unnecessary sacrificial film 15 on the substrate W (step S205). In step S205, plasma is generated from a processing gas for removing the unnecessary sacrificial film 15 in the chamber. The processing gas is, for example, a mixed gas of hydrogen gas and nitrogen gas. Then, the generated plasma removes the unnecessary sacrificial film 15 formed on the side and upper surface of the mask material 14 and the upper surface of the second film 12, as shown in FIG. 2D , for example. In step S205, the unnecessary sacrificial film 15 may be removed under the same processing conditions as in step S105.

[0066] (Deposition of Sealing Film: S206) Next, the apparatus deposits a sealing film covering the sacrificial film 15 (step S206). Step S206 is an example of process (d). In step S206, plasma is generated in a chamber from a process gas such as organic aminosilane. The generated plasma then forms a conformal sealing film 16 covering the sacrificial film 15, as shown in FIG. 5A , for example. The sealing film 16 includes a first portion 16a covering the sacrificial film 15 formed in the recess 60, a second portion 16b continuing from the first portion 16a and covering the mask material 14, and a third portion 16c continuing from the first portion 16a and extending onto the substrate (second film 12). The apparatus may deposit the sealing film 16 to have the same width as the core material 13. The apparatus may deposit the sealing film 16 using the same material as the multiple core materials 13. The sealing film 16 is, for example, a silicon oxide film. The sealing film 16 is not limited to this, and may be made of a material different from that of the core material. For example, the sealing film 16 may be a silicon-containing film such as a silicon nitride film. In step S206, the sealing film 16 may be formed under the same processing conditions as in step S106.

[0067] (Transporting the Substrate: S207) Next, the apparatus transports the substrate W having the sacrificial film 15 and the sealing film 16 (step S207). In step S207, the substrate W is unloaded from the chamber where the process of step S206 was performed, and is transported into a chamber where the process of the next step S208 is performed.

[0068] (Anisotropic Etching: S208) Next, the device removes the second portion 16b and the third portion 16c of the sealing film 16 by etching (step S208). Step S208 is an example of process (f). The etching in step S208 may be anisotropic etching.

[0069] In step S208, the apparatus supplies an etching gas that accelerates etching in the Z direction more than etching in a direction perpendicular to the Z direction into the chamber, and generates plasma. Anisotropic etching is then performed, mainly by ions of the generated plasma, to remove the second portion 16b and the third portion 16c of the sealing film 16.

[0070] (Removal of Mask Material: S209) Next, the apparatus removes the mask material 14 by etching (step S209). Step S209 is an example of the process (f).

[0071] In step S209, the apparatus supplies an etching gas capable of selectively removing the mask material 14 into the chamber and generates plasma. Then, etching is performed using the generated plasma, and the mask material 14 is removed. However, if the apparatus can remove the mask material 14 without using plasma, the mask material 14 may be removed using a method that does not use plasma. As a result, as illustrated in FIG. 5B , the sealing film 16 a and the sacrificial film 15 remain in positions parallel to the core material 13.

[0072] (Removal of Sacrificial Film: S210) Next, the apparatus removes the sacrificial film 15 by etching (step S210). Step S210 is an example of step (e). In the second embodiment, step (e) is performed after step (f).

[0073] In step S210, the apparatus supplies an etching gas into the chamber that selectively etches the sacrificial film 15 relative to the core material 13 and the sealing film 16a, and generates plasma. The apparatus then removes the sacrificial film 15 using the generated plasma. As a result, as illustrated in FIG. 5C , sealing films 16a are formed on both sides of the core material 13 at intervals of 1 / 3 the pitch P of the core material 13.

[0074] (Transporting the Substrate: S211) Next, the apparatus transports the substrate W from the chamber in which the process of step S210 has been performed into a chamber in which the process of the next step S212 will be performed (step S211).

[0075] (Etching of Etching Target Film: S212) Next, the device etches the etching target film (step S212). In step S212, a gas for etching the etching target film is supplied into the chamber, and plasma is generated. The generated plasma then etches the etching target film located below the core material 13 and the sealing film 6 into the pattern of the core material 13 and the sealing film 16a. For example, as shown in FIG. 2J, the core material 13 and the sealing film 16a are used as a mask to etch the second film 12 into the pattern of the core material 13 and the sealing film 16a.

[0076] (Repetition Determination: S213) Next, the device determines whether the processing of steps S200 to S212 has been repeated a set number of times (step S213). The set number of times is a predetermined value equal to or greater than 1. If the device determines that the processing of steps S200 to S212 has not been repeated the set number of times, it returns to step S200 and repeats the processing of steps S200 to S212 until the set number of times has been reached.

[0077] (Transporting the Substrate: S214) When the apparatus determines in step S213 that the processes of steps S200 to S212 have been repeated the set number of times, the apparatus unloads the substrate W from the chamber in which the process of step S212 was performed (step S214). This completes the pattern formation method according to the second embodiment. If the set number of repetitions in the process of S213 is set to 1, a pattern with a pitch that is 1 / 3 the pitch P of the core material 13 is transferred to the second film 12. If the set number of repetitions in the process of S213 is set to 2, the process returns to step S200, and in step S201, the second film 12 and the first film 11 are formed into a structure having a lateral shape. Thereafter, steps S202 to S212 are performed, whereby a pattern with a pitch that is 1 / 3 the pitch P of the first film 11 is transferred to the film (not shown) below the first film 11 in FIG. 2J. This forms a pattern with a pitch that is 1 / 9 the pitch P of the core material 13. When the set number of repetitions is set to 3 in the process of S213, a pattern is formed at a pitch of 1 / 27 of the pitch P of the core material 13. When the set number of repetitions is set to m in the process of S213, a pattern is formed at a pitch of 1 / (3 ｍ ) pitch pattern is formed.

[0078] [Effects] With the pattern formation method according to the second embodiment, the device performs triple patterning, in which a number of patterns whose least common multiple is three times n are formed on n (n is a number equal to or greater than 1) mandrels 13. This allows for a dramatic increase in the number of semiconductor elements that can be formed, and allows for pattern formation even in patterns with narrower gaps, by using a pattern formation method that utilizes the characteristics of patterning instead of air gap formation, in order to contribute to productivity and miniaturization in the semiconductor patterning process. Specifically, the device performs the processes of steps S200 to S212 m (m is a number equal to or greater than 1) times, thereby forming (n×3 ｍ) patterns are formed. m is the set number of repetitions. When m is 1, (n × 3) mask patterns are formed for n mandrels 13. For example, when m is 1, nine patterns are formed for three mandrels 13, as shown in FIG. 5C. That is, the pitch of the formed mask patterns is P / 3, which is one-third of the pitch P of the mandrels 13. This allows the device to transfer a pattern with a pitch that is one-third of the pitch P of the mandrels 13 to the film to be etched.

[0079] In the pattern formation method according to the second embodiment, after thinning the mandrel 13 in S201, a sacrificial film 15 is formed in S203, and a sealing film 16 having the same width as the mandrel 13 is formed in S206 without forming an air gap. Thereafter, in S208, a second portion 16b and a third portion 16c of the sealing film 16 are etched by anisotropic etching, and in S209, the mask material 14 is removed, and then the sacrificial film 15 is etched and removed using plasma or the like. As a result, the sealing film 16a and the mandrel 13 remain.

[0080] The triple patterning formed by the pattern formation method according to the second embodiment can also achieve the same effects as the first embodiment, and can contribute to the productivity and miniaturization of the semiconductor patterning process.

[0081] [Example of Apparatus] An example of an apparatus for performing the process of step S108 for removing the sacrificial film 15 by depolymerization will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of the apparatus. However, the apparatus for performing each step of the pattern formation method according to the first embodiment and the pattern formation method according to the second embodiment is not limited to the apparatus shown in Fig. 6.

[0082] The apparatus for performing the process in step S108 may be a capacitively coupled plasma processing apparatus shown in Fig. 6 or an inductively coupled plasma processing apparatus. The apparatus may also be a single-wafer type substrate processing apparatus that processes substrates W one by one, or a batch type substrate processing apparatus that processes multiple substrates W simultaneously.

[0083] The apparatus 30 includes a chamber 31 and a control unit 40. The chamber 31 is made of a conductive material and is grounded. An exhaust mechanism 32 is connected to the chamber 31. The exhaust mechanism 32 has a pressure adjustment valve. The exhaust mechanism 32 exhausts gas from the chamber 31 and controls the pressure adjustment valve so that the pressure inside the chamber 31 is set to a predetermined value.

[0084] A stage 33 on which a substrate W is placed is provided within the chamber 31. The substrate W is loaded into and unloaded from the chamber 31 through a loading / unloading port 31a formed in a sidewall of the chamber 31 and placed on the stage 33. When the substrate W is being transported, the loading / unloading port 31a is opened and closed by a gate valve G. A heater 33a for heating the substrate W is provided within the stage 33. The stage 33 is electrically connected to the bottom wall of the chamber 31 and functions as an anode electrode. A shower head 34 is provided above the stage 33 so as to face the upper surface of the stage 33. The shower head 34 is made of a conductive material and is supported on the upper part of the chamber 31 via an insulating member 34a. A power source 35 for supplying high-frequency power for generating plasma is connected to the shower head 34. The shower head 34 functions as a cathode electrode relative to the stage 33.

[0085] The gas supply source 36 supplies a process gas. The flow rate controller 37 adjusts the flow rate of the process gas supplied from the gas supply source 36 and supplies it into the diffusion space 34b of the shower head 34. The process gas supplied into the diffusion space 34b is diffused within the diffusion space 34b and supplied in a shower-like manner into the chamber 31 from a plurality of outlet ports 34c formed in the lower surface of the diffusion space 34b. In the example of FIG. 6, one gas supply source 36 and one flow rate controller 37 are shown, but in reality, a set of the gas supply source 36 and the flow rate controller 37 is provided for each type of gas used.

[0086] The processing gas supplied into the chamber 31 via the shower head 34 is converted into plasma by high-frequency power supplied into the chamber 31 from the power source 35. Then, the activated species contained in the plasma decompose and gasify the monomers generated during the removal of the sacrificial film 15.

[0087] The control unit 40 processes computer-executable instructions that cause the apparatus 30 to perform various steps included in the pattern formation method described in this disclosure. The control unit 40 may be configured to control each element of the apparatus 30 to perform the various steps described herein. In one embodiment, part or all of the control unit 40 may be included in the apparatus 30. The control unit 40 may include a processing unit, a storage unit, and a communication interface. The control unit 40 is realized, for example, by a computer. The processing unit may be configured to perform various control operations by reading a program from the storage unit and executing the read program. This program may be stored in the storage unit in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit and read from the storage unit by the processing unit for execution. The medium may be various computer-readable storage media or a communication line connected to the communication interface. The processing unit may be a CPU (Central Processing Unit). The storage unit may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), a SSD (Solid State Drive), or a combination thereof. The communication interface communicates with the device 30 via a communication line such as a LAN (Local Area Network).

[0088] The above describes the embodiments. As described above, the pattern formation method according to the first embodiment and the pattern formation method according to the second embodiment include steps (a) to (f). In step (a), a substrate W is prepared, including a core material 13 having a side surface and a top surface, and a mask material 14 provided on the top surface of the core material 13 and having a side surface that is continuous with the side surface of the core material 13. In step (b), a recess is formed by etching the side surface of the core material 13 so that at least a portion of the side surface of the core material 13 is located inside the side surface of the mask material 14. In step (c), a sacrificial film 15 is embedded in a recess 60 formed by the core material 13, the mask material 14, and the substrate. In step (d), a sealing film 16 is formed, including a first portion 16a covering the sacrificial film 15 formed in the recess 60, a second portion 16b covering the mask material 14 in a continuous manner with the first portion 16a, and a third portion 16c extending on the substrate in a continuous manner with the first portion 16a. In step (e), the sacrificial film 15 is removed. In step (f), the second portion 16b and the third portion 16c of the sealing film 16 are removed by etching.

[0089] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0090] The following supplementary note is further disclosed regarding the above embodiment: (Supplementary Note 1) A method for forming a pattern on a substrate, comprising: (a) preparing the substrate including a core material having side surfaces and a top surface, and a mask material provided on the top surface of the core material and having side surfaces that are continuous with the side surfaces of the core material, (b) etching the side surfaces of the core material to form recesses so that at least a portion of the side surfaces of the core material is located more inward than the side surfaces of the mask material, (c) embedding a sacrificial film in the recesses formed by the core material, the mask material, and the substrate, (d) forming a sealing film having a first portion covering the sacrificial film formed in the recesses, a second portion covering the mask material and continuous with the first portion, and a third portion extending on the substrate and continuous with the first portion, (e) removing the sacrificial film, and (f) removing the second and third portions of the sealing film by etching. (Appendix 2) The pattern formation method according to Appendix 1, wherein (c) embeds the sacrificial film in the recess by polymerization of a plurality of types of monomers. (Appendix 3) The pattern formation method according to Appendix 1 or Appendix 2, wherein (e) forms an air gap in the recess by removing the sacrificial film by depolymerization. (Appendix 4) The pattern formation method according to Appendix 3, wherein (f) is performed after (e). (Appendix 5) The pattern formation method according to Appendix 4, including (g) changing the shape of the sealing film between (e) and (f). (Appendix 6) The pattern formation method according to Appendix 1, wherein (e) is performed after (f). (Appendix 7) The pattern formation method according to any one of Appendices 1 to 6, wherein (d) deposits the sealing film of the same material as the core material. (Supplementary Note 8) The pattern formation method according to any one of Supplementary Notes 1 to 6, wherein (d) forms the sealing film of a material different from that of the core material. (Supplementary Note 9) The pattern formation method according to any one of Supplementary Notes 1 to 8, wherein the pattern formation method forms patterns of a number such that the least common multiple is three times n for n (n is a number equal to or greater than 1) core materials.(Supplementary Note 10) By executing the steps (a) to (f) m times (m is a number equal to or greater than 1), n ​​core materials are subjected to the process (n×3. ｍ ) patterns are formed. (Appendix 11) The pattern formation method according to any one of Appendices 1 to 10, wherein the etching in (b) is isotropic etching. (Appendix 12) The pattern formation method according to any one of Appendices 1 to 11, wherein the etching in (f) is anisotropic etching. (Appendix 13) The pattern formation method according to Appendices 3, wherein in step (e), the sacrificial film is removed by depolymerization using thermal energy. (Appendix 14) The pattern formation method according to Appendices 13, wherein in step (e), the sacrificial film is removed by using plasma. (Appendix 15) A method for forming a pattern on a substrate, comprising: a step of forming a sacrificial film covering side surfaces of a core material formed on the substrate; a step of forming a sealing film covering the sacrificial film; and a step of removing the sacrificial film, wherein the sacrificial film is formed by a vapor deposition polymerization reaction of a plurality of types of monomers and is removed by depolymerization.

[0091] 13: Core material 14: Mask material 15: Sacrificial film 16: Sealing film 17: Air gap 60: Recess W: Substrate

Claims

1. A method for forming a pattern on a substrate, comprising: (a) preparing the substrate including a core material having side surfaces and a top surface, and a mask material provided on the top surface of the core material and having side surfaces that are continuous with the side surfaces of the core material; (b) etching the side surfaces of the core material to form recesses so that at least a portion of the side surfaces of the core material are located inside the side surfaces of the mask material; (c) embedding a sacrificial film in the recesses formed by the core material, the mask material, and the substrate; (d) forming a sealing film having a first portion covering the sacrificial film formed in the recesses, a second portion covering the mask material continuous with the first portion, and a third portion extending on the substrate continuous with the first portion; (e) removing the sacrificial film; and (f) removing the second and third portions of the sealing film by etching.

2. The pattern formation method according to claim 1, wherein (c) comprises filling the recesses with the sacrificial film by polymerization of a plurality of types of monomers.

3. The pattern formation method according to claim 2, wherein (e) forms an air gap in the recess by removing the sacrificial film through depolymerization.

4. The pattern formation method according to claim 3, wherein (f) is carried out after (e).

5. The pattern forming method according to claim 4, further comprising: (g) changing the shape of the sealing film between (e) and (f).

6. The pattern formation method according to claim 1, wherein (e) is carried out after (f).

7. The pattern forming method according to any one of claims 1 to 6, wherein (d) forms the sealing film of the same material as the core material.

8. The pattern forming method according to any one of claims 1 to 6, wherein (d) forms the sealing film of a material different from that of the core material.

9. The pattern formation method according to any one of claims 1 to 6, wherein the pattern formation method forms patterns of a number such that the least common multiple is three times n for n (n is a number equal to or greater than 1) core materials.

10. By executing steps (a) to (f) m times (m is a number equal to or greater than 1), n ​​core materials are subjected to (n×3 ｍ The pattern forming method according to claim 9 , wherein ) patterns are formed.

11. The pattern formation method according to any one of claims 1 to 6, wherein the etching in (b) is isotropic etching.

12. The pattern formation method according to any one of claims 1 to 6, wherein the etching in (f) is anisotropic etching.

13. The pattern formation method according to claim 3, wherein in step (e), the sacrificial film is removed by depolymerization using thermal energy.

14. The pattern formation method according to claim 13, wherein in step (e), the sacrificial film is removed using plasma.

15. A method for forming a pattern on a substrate, comprising the steps of: forming a sacrificial film that covers a side surface of a core material formed on the substrate; forming a sealing film that covers the sacrificial film; and removing the sacrificial film, wherein the sacrificial film is formed by a vapor deposition polymerization reaction of multiple types of monomers and is removed by depolymerization.

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