Substrate processing method and substrate processing apparatus

Abstract

A substrate processing method and a substrate processing apparatus are provided. The substrate processing method performed by the substrate processing apparatus includes steps a, b and c. Step a is a step of providing a substrate having an etched film and a mask formed on the etched film. Step b is a step of forming a protective film on an upper portion of an opening of the mask. Step c is a step of etching the mask while suppressing variation in the opening size of the upper portion of the opening with the protective film, and varying the size of a lower portion of the opening which is not covered with the protective film. According to the present invention, abnormality in the shape of a pattern formed on a substrate can be suppressed.

Description

Technical Field

[0001] The following invention relates to substrate processing methods and substrate processing apparatus. Background Technology

[0002] As semiconductor device integration advances not only horizontally but also vertically, the aspect ratio of patterns formed during semiconductor device manufacturing is also increasing. For example, in the manufacturing of 3D NAND, vias are formed in directions that penetrate multiple metal wiring layers. In the case of forming a 64-layer memory cell, the aspect ratio of the vias is 45.

[0003] To form high aspect ratio patterns with high precision, various methods have been proposed. For example, a method has been proposed to suppress lateral etching by repeatedly etching and depositing films on openings in the dielectric material formed on a semiconductor substrate (Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: U.S. Patent Application Publication No. 2016 / 0343580. Summary of the Invention

[0007] The problem the invention aims to solve

[0008] This invention provides a technique for suppressing shape anomalies in patterns formed on a substrate.

[0009] Technical means for solving problems

[0010] One aspect of the substrate processing method of the present invention includes steps a, b, and c. Step a is the step of providing a substrate having an etched film and a mask formed on the etched film. Step b is the step of forming a protective film on the upper part of the opening of the mask. Step c is the step of etching the mask while using the protective film to suppress the change in the opening size at the upper part of the opening, so that the size of the lower part of the opening not covered by the protective film changes.

[0011] Invention Effects

[0012] According to the present invention, it is possible to suppress shape abnormalities of patterns formed on a substrate. Attached Figure Description

[0013] Figure 1 This is a flowchart illustrating an example of the substrate processing method of an implementation method.

[0014] Figure 2A This is a diagram illustrating an example of the object being processed in the substrate processing method of an embodiment.

[0015] Figure 2B This is a diagram illustrating an example of the object being processed in the substrate processing method of an embodiment.

[0016] Figure 2C This is a diagram illustrating an example of the object being processed in the substrate processing method of an embodiment.

[0017] Figure 2D This is a diagram illustrating an example of the object being processed in the substrate processing method of an embodiment.

[0018] Figure 3A This is a diagram illustrating Example 1 of the process for forming the protective film in the embodiment.

[0019] Figure 3B This is a diagram illustrating Example 1 of the process for forming the protective film in the embodiment.

[0020] Figure 3C This is a diagram illustrating Example 1 of the process for forming the protective film in the embodiment.

[0021] Figure 3D This is a diagram illustrating Example 1 of the process for forming the protective film in the embodiment.

[0022] Figure 4A This is a diagram illustrating Process Example 2 for forming the protective film of the embodiment.

[0023] Figure 4B This is a diagram illustrating Process Example 2 for forming the protective film of the embodiment.

[0024] Figure 4C This is a diagram illustrating Process Example 2 for forming the protective film of the embodiment.

[0025] Figure 5 This is a flowchart illustrating another example of the substrate processing method of an implementation method.

[0026] Figure 6A This is a diagram illustrating the shape 1 formed by the substrate processing method of the embodiment.

[0027] Figure 6B This is a diagram illustrating the shape 1 formed by the substrate processing method of the embodiment.

[0028] Figure 6C This is a diagram illustrating the shape 1 formed by the substrate processing method of the embodiment.

[0029] Figure 6D This is a diagram illustrating the shape 1 formed by the substrate processing method of the embodiment.

[0030] Figure 6E This is a diagram illustrating the shape 1 formed by the substrate processing method of the embodiment.

[0031] Figure 7A This is a diagram illustrating shape 2 formed by the substrate processing method of the embodiment.

[0032] Figure 7B This is a diagram illustrating shape 2 formed by the substrate processing method of the embodiment.

[0033] Figure 7C This is a diagram illustrating shape 2 formed by the substrate processing method of the embodiment.

[0034] Figure 7D This is a diagram illustrating shape 2 formed by the substrate processing method of the embodiment.

[0035] Figure 7E This is a diagram illustrating shape 2 formed by the substrate processing method of the embodiment.

[0036] Figure 8 This is a diagram illustrating an example of the general structure of a substrate processing apparatus according to an embodiment.

[0037] Explanation of reference numerals in the attached figures

[0038] 10. Substrate processing device

[0039] 12 chambers

[0040] 12c space

[0041] 12e exhaust port

[0042] 12i intake port

[0043] 12p Opening

[0044] 13 Supporting Mechanism

[0045] 14. Substrate support stage

[0046] 16 Electrostatic Chucks

[0047] 18 Lower electrode

[0048] 18a First Board

[0049] 18b Second Board

[0050] 22 DC power supply

[0051] 23 Switches

[0052] 24 flow path

[0053] Pipelines 26a and 26b

[0054] 28 Gas supply pipeline

[0055] 30 RF power supply

[0056] 32 Matcher

[0057] 34. Covering components

[0058] 36 Piping

[0059] 38 Exhaust device

[0060] 40 baffles

[0061] 42 windows

[0062] 44 Gas Supply Department

[0063] 44a Gas Source

[0064] 44b Flow Controller

[0065] 44c valve

[0066] 46 Piping

[0067] 48 Gate valve

[0068] 50 antennas

[0069] 52A inner antenna element

[0070] 52B outer antenna element

[0071] 60 shielding parts

[0072] 70A, 70B RF power supplies

[0073] 80 controller

[0074] 100 substrate

[0075] 101 Etched film

[0076] 102 Mask

[0077] 200, 200A, 200C Opening

[0078] Bottom of 201, 201A, 201C

[0079] 202, 202A, 202C sidewalls

[0080] 203 Top

[0081] 300, 300A, 300C Protective Film

[0082] FR edge ring

[0083] HT heater

[0084] HP heater power supply

[0085] W substrate

[0086] EL1 etched film

[0087] MA mask

[0088] OP opening

[0089] P precursor

[0090] R Reaction Gas

[0091] S, S1, and S3 are the processed entities. Detailed Implementation

[0092] The disclosed embodiments will now be described in detail based on the accompanying drawings. Furthermore, these embodiments are not limiting. Moreover, the various embodiments can be appropriately combined without causing contradictions in the processing content. Additionally, the same or equivalent parts are labeled with the same reference numerals in the various figures.

[0093] In the following description, "pattern" refers to all shapes formed on the substrate. A pattern refers to a collection of multiple shapes formed on the substrate, such as holes, slots, lines, and spaces. Furthermore, "opening" refers to a portion of a pattern formed on the substrate that is recessed in the thickness direction of the substrate. An opening includes: a "sidewall" which is the inner circumferential surface of the recessed shape; a "bottom" which is the bottom portion of the recessed shape; and a "top," which is the substrate surface near the sidewall that is continuous with the sidewall. Additionally, 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 enclosed by the bottom and sidewalls, or any location within the space.

[0094] "Longitudinal" refers to the thickness direction of multiple films formed on a substrate. The longitudinal direction is approximately perpendicular to the substrate surface. "Transverse" refers to the direction parallel to the substrate surface. The transverse direction is approximately perpendicular to the longitudinal direction. Furthermore, neither the longitudinal nor transverse direction strictly refers to only one direction, and some degree of error is permissible.

[0095] In recent years, the technology of processing high aspect ratio holes has attracted much attention in semiconductor manufacturing. One example is the High Aspect Ratio Contact (HARC). HARCs are used in DRAM (Dynamic Random Access Memory) and 3D NAND. The aspect ratio of HARCs used in DRAM is, for example, 45, while the aspect ratio of HARCs used in 3D NAND exceeds 65.

[0096] In HARC fabrication, for example, a silicon oxide film, an amorphous carbon layer (ACL), a silicon oxynitride film (SiON), a bottom anti-reflection coating (BARC), and a photoresist film are stacked on a substrate. Then, a pattern transferred to the photoresist is sequentially transferred to the next layer to form a pattern. However, for holes with high aspect ratios, it is difficult to form holes that are vertically perpendicular. For example, a phenomenon known as bowing (bow-shaped) is where the vertical center of the hole expands laterally. Furthermore, a phenomenon known is where the hole gradually decreases in size (conical) towards the bottom.

[0097] (Implementation Method)

[0098] The substrate processing method of the embodiment suppresses shape anomalies of patterns formed on the substrate, such as lateral bending or tapering. Furthermore, the substrate processing method according to the embodiment can increase the degree of freedom in controlling the shape of the pattern to be formed. Figure 1 This is a flowchart illustrating an example of the substrate processing method of an implementation method. Figures 2A to 2D This is a diagram illustrating an example of a substrate processed by the substrate processing method of the embodiment.

[0099] First, provide the object to be processed, S (refer to...). Figure 2A (Step S101). The object to be processed S includes a substrate 100, an etchable film 101 formed on the substrate 100, and a mask 102 (see reference). Figure 2A The mask 102 has an opening 200. The opening 200 has a bottom 201 and a sidewall 202.

[0100] Next, a protective film 300 is formed on the mask 102 (step S102). The protective film 300 is formed on the top 203 and sidewall 202 of the opening 200. Figure 2B In this example, the protective film 300 is formed such that its thickness gradually decreases from the upper side to the lower side of the sidewall 202. The method for forming the protective film 300 is described later.

[0101] Next, the mask 102 on which the protective film 300 is formed is etched (trimmed) (step S103). At this time, the portion of the sidewall 202 covered by the protective film 300 is not etched, while the portion below that is not covered or where the protective film 300 is thinner than the upper portion is etched, resulting in an increase in width compared to the upper portion (see reference). Figure 2C The process may also include a step to determine whether the dimension (lateral dimension) of the bottom 201 of the opening 200 is greater than or equal to a predetermined value (step S104). The dimension of the bottom 201 is also referred to as the bottom CD (CD: Critical Dimension). If, in step S104, it is determined that the bottom CD of the opening 200 is not greater than or equal to a predetermined value (step S104, No), the process returns to S103. On the other hand, if it is determined that the bottom CD of the opening 200 is greater than or equal to a predetermined value (step S104, Yes), the etched film 101 is etched (step S105). Then, the process ends. The shape of the opening 200 is as follows... Figure 2D The changes are as shown.

[0102] In this way, in the substrate processing method of the embodiment, the protective film 300 is formed on the sidewall 202 in such a manner that the film thickness decreases from the upper side to the lower side, thereby suppressing the reduction of the bottom CD in the mask 102. Therefore, it is possible to suppress the abnormality of the shape of the pattern in the etched film 101 caused by the shape of the mask 102.

[0103] Furthermore, in the substrate processing method of the embodiment, a protective film 300 can be formed during etching of the etched film 101. Therefore, lateral bending can be suppressed. Also, the protective film 300 can be formed such that its thickness decreases from the upper side to the lower side, thus suppressing the reduction of the bottom CD of the opening 200 in the etched film 101.

[0104] (Judging from the bottom CD)

[0105] The method for judgment in step S104 is not limited. For example, the bottom CD can be determined by examining the shape of the processed object S using optical means. Alternatively, the bottom CD can be determined based on the number of times or execution time of at least one of steps S102 and S103. The "predetermined value" in step S104 is preset based on the design value.

[0106] (Determining whether a protective film should be formed)

[0107] It is also possible to determine whether to form a protective film. The method of determination is not particularly limited. For example, the thickness and / or location of the protective film 300 remaining on the sidewall 202 can be used to determine whether to form the protective film 300. Furthermore, for example, the number of times or execution time of at least one of steps S102 and S103 can be used to determine whether to form the protective film 300.

[0108] Alternatively, step S104 and the determination of whether to form a protective film can be performed together. For example, the process can end if the number of executions of steps S102 and S103 reaches a value V1. Furthermore, the protective film 300 can be formed if the number of executions of steps S102 and S103 does not meet a value V2 (V2 < V1). Alternatively, etching (S103) can be performed without forming the protective film 300 if the number of executions of steps S102 and S103 does not meet a value V3 (V3 < V2).

[0109] (Types of membranes)

[0110] The types of films for the etched film 101, mask 102, and protective film 300 are not particularly limited. For example, the substrate 100 can be a silicon wafer. The etched film 101 can be a dielectric film, such as a silicon-containing dielectric film. The etched film 101 can be formed by stacking multiple types of films. For example, the etched film 101 can be a layer formed by sequentially stacking a silicon oxide film and a silicon nitride film. The etched film 101 can be a layer formed by sequentially stacking a silicon oxide film and a polycrystalline silicon film. The mask 102 can be a carbon-containing film. The carbon-containing film can be formed from an amorphous carbon layer (ACL) or a spin-coated carbon film (SOC). Alternatively, the mask 102 can be formed from a metal film. Furthermore, although in Figures 2A to 2D Although not illustrated, a silicon nitride oxide film (SiON) and a back antireflective film (BARC) with the same opening pattern as the mask 102 may also exist on the mask 102. The protective film 300 may be a silicon-containing film.

[0111] In the substrate processing method of the embodiment, when the etched film 101 is a silicon-containing dielectric film, it can be a carbon-containing film such as ACL or SOC. Furthermore, when the etched film 101 is a polycrystalline silicon film, it can be a silicon oxide film formed using TEOS (tetraethyl orthosilicate).

[0112] (Methods for forming a protective film)

[0113] The method used to form the protective film 300 is not particularly limited. For example, atomic layer deposition (ALD), subconformal ALD, chemical vapor deposition (CVD), physical vapor deposition (PVD), molecular layer deposition (MLD), etc., can be used. The process of step S102 can be achieved by any one or a combination of ALD, subconformal ALD, CVD, PVD, and MLD. Furthermore, if more of the protective film 300 is formed on the upper side of the sidewall 202 of the opening 200 than on the lower side of the sidewall 202, step S102 can be achieved by any one of CVD and subconformal ALD, or a combination of multiple processes including either one.

[0114] (Example 1 of membrane formation methods - Subconformal ALD)

[0115] The subconformal ALD will be explained below. Figures 3A to 3D This is a diagram illustrating Process Example 1 for forming the protective film 300 in the embodiment. Furthermore, Figures 4A to 4C This is a diagram illustrating a processing example 2 for forming the protective film 300 of the embodiment.

[0116] Before explaining subconformal ALD, let's first explain what ALD is. ALD typically involves four steps. First, in the first step, a first gas (also called a precursor or first reactant) is introduced into a chamber (processing container) containing the object to be processed. At this time, plasma can be generated from the first gas. A first material contained in the first gas adsorbs onto the surface of the object to be processed. After the surface is covered by the first material, the chamber is purged (second step: purging). Next, a second gas (also called a reactant or second reactant) containing a second material that can react with the first material is introduced into the chamber. At this time, plasma can be generated from the second gas. The second material reacts with the first material on the object to form a film. ALD controls the adsorption of a specified material onto a substance present on the surface of the object to be processed and reacts with it to form a film. Therefore, ALD typically achieves conformal film formation by setting a sufficient processing time.

[0117] In contrast, subconformal ALD sets the treatment conditions so that self-controlled adsorption or reaction on the surface of the treated object does not occur. At least two of the following treatment methods exist.

[0118] (1) The precursor is adsorbed onto the entire surface of the object being treated. Then, the introduced reactive gas is controlled so that it does not spread across the entire surface of the precursor adsorbed onto the object being treated.

[0119] (2) Only a portion of the precursor is adsorbed onto the surface of the object being treated. Then, the introduced reactive gas reacts only with the precursor adsorbed onto the surface of the object being treated.

[0120] One embodiment of the substrate processing method uses method (1) or (2) to form a film with a reduced film thickness along the stacking direction on the sidewall of the opening having a mask.

[0121] Figures 3A to 3D This refers to the above method (1). Figure 3A The object to be processed shown includes an etched film EL1 and a mask MA formed on a substrate (not shown). An opening OP is formed on the mask MA.

[0122] First, the precursor P is introduced into the chamber containing the object to be processed. Figure 3A By setting sufficient treatment time, the precursor P is adsorbed onto the entire surface of the treated object. Figure 3B Alternatively, the precursor P can be plasma-entrained and then adsorbed. After the adsorption of the precursor P is complete, the chamber is purged (arbitrary). Then, the reaction gas R is introduced into the chamber. Figure 3C Alternatively, the reactive gas R can be plasma-entrained. The introduced reactive gas R reacts with the precursor P on the substrate, gradually advancing film formation from above the mask MA. Here, the reactive gas R (arbitrarily) is purged before the film formation reaches below the mask MA. By processing in this way, a film can be formed on a portion of the sidewall of the opening of the mask MA. Figure 3D (). One part refers to, for example, the upper part of an opening.

[0123] Figures 4A to 4C This refers to the above method (2). Figure 4A The object being processed shown has the same Figure 3A The same shape. Figure 4A In this example, the precursor P is adsorbed only onto the upper part of the treated object. For example, the precursor P is adsorbed by CVD. Similarly to the above method (1), the precursor P can also be plasma-entrained. After purging the precursor P, the reaction gas R is introduced into the chamber ( Figure 4B Alternatively, the reactive gas R can be plasma-entrained. In this case, the reactive gas R reacts only at the sites where the precursor P is adsorbed to form a film, therefore the film forms only above the treated body. Figure 4C ).

[0124] As described above, in the subconformal ALD, the adsorption of the precursor in Processing Example 2 or the reaction of the reactive gas in Processing Example 1 is confined to a specific portion of the treated body. For example, a film is formed only on the upper part of the opening sidewall. Processing parameters adjusted to allow for selective film formation include, for example, the temperature of the stage on which the treated body is placed, the pressure inside the chamber, the flow rate and pressure of the introduced reactive gas, and the processing time. Furthermore, for processes using plasma, the film formation position can also be adjusted by regulating the value of the high-frequency (RF) electrical power applied to generate the plasma.

[0125] The substrate processing method of the embodiment controls the shape of the opening 200 formed by etching by controlling the position and thickness of the protective film 300 on the sidewall 202.

[0126] (shape example)

[0127] exist Figures 2A to 2D The example describes the case where a hole with approximately the same opening size is formed from the top to the bottom of the etched film 101. However, this method is not limited to this; the substrate processing method of this embodiment can also be used to form a conical hole. The substrate processing method of this embodiment can form holes, for example, in a regular conical shape and an inverted conical shape.

[0128] (Shape Example 1 - Right Cone)

[0129] Figure 5 This is a flowchart illustrating another example of the substrate processing method in an implementation. Figures 6A-6E This diagram illustrates shape 1 (conical) formed by the substrate processing method of the embodiment. The conical shape refers to the shape of the hole that gradually tapers from the upper side to the lower side.

[0130] Figure 5 The process shown is the same as Figure 1 The processes shown are roughly the same. Figure 5 Steps S501 to S503 and Figure 1 The steps S101 to S103 correspond to each other. Figure 5 Step S504 is the step of determining whether to end the process. Whether to end the process can be determined, for example, based on whether the aspect ratio of the opening formed in the processed body has reached a specified value. Whether to end the process can also be determined based on whether the number of executions in steps S502 and 503 has reached a threshold.

[0131] Figure 6A The workpiece S1 shown has an etchable film 101, a mask layer 102A, and a second mask 103 formed on a substrate 100. Furthermore, openings 200A are formed in the mask layer 102A and the second mask 103. First, the workpiece S1 ( Figure 5(Step S501). Next, a protective film 300A is formed on the sidewall 202A of the opening 200A. Figure 5 (Step S502). Figure 6B In this example, the protective film 300A is formed such that it covers the entire surface of the sidewall 202A with approximately the same film thickness. For example, the protective film 300A is formed by ALD. Next, the body S1 to be processed is etched. Figure 5 (Step S503). Through etching, the aspect ratio of the opening 200A becomes higher. The lower side of the sidewall 202A of the opening 200A is not covered by the protective film 300A (see reference). Figure 6C ).

[0132] Next, determine whether to end the processing. Figure 5 (Step S504). The judgment criterion is, for example, whether the aspect ratio has reached a specified value. Figure 6C In the example, the aspect ratio of opening 200A did not meet the specified value, therefore it was determined that the processing should not be terminated. Figure 5 (If the condition is not met in step S504, return to step S502.) After the protective film 300A is formed in step S502, etching is performed (refer to...). Figure 6D ).

[0133] As shown in this way, while a protective film 300A is formed on the entire sidewall 202A of the opening 200A, the opening 200A is deepened, and the shape of the opening 200A is formed into a positive cone shape that gradually tapers from the top to the bottom.

[0134] When the etched film 101 is etched through a mask 102 of a positive conical shape, the shape of the mask 102 is transferred to the etched film 101, forming a conical shape that tapers towards the bottom. Figure 6E ).

[0135] As described above, the substrate processing method according to the embodiment can gradually deepen the opening 200A while maintaining the shape of the sidewall 202A of the final formed opening 200A. Therefore, the protective film 300A can be used to suppress shape abnormalities of the sidewall 202A. Furthermore, according to the embodiment, as... Figures 6A-6E The opening 200A shown is capable of forming a positive conical shape.

[0136] (Shape example 2 - inverted taper)

[0137] Figures 7A to 7E This diagram illustrates shape 2 (inverted cone) formed by the substrate processing method of the embodiment. The inverted cone shape refers to the shape of a hole whose opening size gradually increases from the upper side to the lower side.

[0138] Figure 7AThe workpiece S3 shown has an etchable film 101, a mask layer 102B, and a second mask 103 formed on a substrate 100. Furthermore, openings 200C are formed in the mask layer 102B and the second mask 103. First, the workpiece S3 ( Figure 5 (Step S501).

[0139] Next, a protective film 300C is formed on the sidewall 202C of the opening 200C. Figure 5 (Step S502). Figure 7B In the example, the protective film 300C is formed with different film thicknesses on the upper and lower sides of the sidewall 202C. Figure 7B For example, a protective film 300C is formed via CVD or subconformal ALD. In Figure 7B In this example, the lower end of the protective film 300C is located above the bottom 201C. Furthermore, the protective film 300C is formed to be consistent with the protective film 300 (…). Figure 2B It is located on the upper side compared to the lower end.

[0140] Next, the etched body S3 ( Figure 5 (Step S503). Through etching, the aspect ratio of the opening 200C becomes higher. The lower part of the sidewall 202C of the opening 200C is not covered by the protective film 300C (see reference). Figure 7C In addition, with Figure 6C Different examples, Figure 7C The lateral dimension of the opening 200C gradually increases as it moves from the mask layer 102B side to the etched film 101 side.

[0141] At this moment, the aspect ratio of the opening 200C does not reach the specified value, therefore it is determined that the process should not end (step S504, No). Then, the process returns to step S502 to form the protective film 300C. At this time, the protective film 300C is formed in a manner where the film thickness gradually decreases as it moves from top to bottom. Then, etching is performed.

[0142] As described above, a protective film 300C is formed such that its thickness gradually decreases from the upper side of the sidewall 202C of the opening 200C to the lower side, and its lower end is located above the bottom 201C, while the opening 200C is deepened. In this way, the shape of the opening 200C is formed as an inverted cone shape that gradually expands laterally from the upper side to the lower side. Figure 7D ).

[0143] Next, when etching the etched film 101, it is formed as follows: Figure 7E The shape. By etching the etched film 101 while simultaneously forming the protective film 300C, the opening shape in the etched film 101 can also be formed into the same inverted cone shape as the opening shape in the mask 102.

[0144] In shape 2, the protective film 300C is formed with varying thicknesses depending on the location of the opening 200C. Therefore, the protective film 300C can be formed thicker in areas prone to lateral bending, and thinner near the bottom 201C of the opening 200C where ions or free radicals are less likely to reach. Thus, the substrate processing method according to this embodiment can suppress lateral bending and prevent reduction of the bottom CD. Furthermore, in shape 2, the protective film 300C (… Figure 2B Compared to the bottom 201C, a thicker protective film 300C is formed on the upper side. Furthermore, the protective film 300C is formed at the lower end, positioned higher than the bottom 201C. Therefore, compared to... Figure 2B Compared to the previous example, shape 2 can more effectively utilize the etching effect of the bottom 201C of the opening 200C. Therefore, it is possible to form an inverted conical opening 200C.

[0145] As described above, the substrate processing method according to the embodiment can gradually deepen the opening 200C while maintaining the shape of the sidewall 202C of the final formed opening 200C. Furthermore, by thinning the protective film 300C near the bottom 201C of the opening 200C, where the influence of ions or free radicals is weaker, the etching effect can sufficiently affect the bottom 201C of the opening 200C.

[0146] As described above, according to the embodiment, by adjusting the position and thickness of the protective film, openings of various shapes such as conical, vertical hole, and inverted conical can be formed.

[0147] (Mask Correction)

[0148] In addition, the substrate processing method described above can also be used to suppress shape abnormalities in either the mask 102 (mask layers 102A, 102B) or the etched film 101.

[0149] When a shape abnormality occurs in the mask 102, shape correction is considered by forming a film at the location of the abnormality. However, in such cases, the material used for shape correction of the mask 102 is sometimes the same material as the material of the etched film 101. In this case, during the etching of the etched film 101, the material used for shape correction is also removed, and the shape of the mask 102 deforms. Therefore, it is preferable to use a single material constituting the mask 102. Thus, the material of the protective film is selected in such a way that the material constituting the mask 102 is a single material. Therefore, the substrate processing method of the above embodiment is advantageous in suppressing the occurrence of shape abnormalities in the mask 102.

[0150] Furthermore, the substrate processing method of the embodiment may or may not use plasma in the protective film formation in step S102 and the etching in step S103.

[0151] (Example of the configuration of a substrate processing device)

[0152] Figure 8 This is a diagram showing the outline structure of the substrate processing apparatus 10 according to the embodiment. Figure 8 The substrate processing apparatus 10 shown can be used to implement the substrate processing method of the embodiment. Figure 8 The substrate processing apparatus 10 is a so-called inductively-coupled plasma (ICP) apparatus, having a plasma source for generating ICP. However, the substrate processing apparatus of the embodiment may also utilize plasma generated by other methods. For example, the substrate processing apparatus of the embodiment may be an apparatus utilizing capacitively-coupled plasma (CCP), ECR plasma (electron-cyclotron-resonance plasma), helical wave excited plasma (HWP), or surface wave plasma (SWP), etc.

[0153] The substrate processing apparatus 10 has a chamber 12. The chamber 12 is formed of a metal such as aluminum. The chamber 12 is, for example, generally cylindrical in shape. A space 12c for performing processing is provided inside the chamber 12.

[0154] A substrate support stage 14 is disposed below space 12c. The substrate support stage 14 is capable of holding the substrate W placed thereon. The substrate W is, for example, a substrate processed by a method according to one embodiment.

[0155] The substrate support stage 14 can be supported by the support mechanism 13. The support mechanism 13 extends upward from the bottom of the chamber 12 within the space 12c. The support mechanism 13 can be generally cylindrical. The support mechanism 13 can be made of an insulating material such as quartz.

[0156] The substrate support stage 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, generally cylindrical. The second plate 18b is disposed on the first plate 18a. The second plate 18b is electrically connected to the first plate 18a.

[0157] An electrostatic chuck 16 is disposed on the second plate 18b. The electrostatic chuck 16 has an insulating layer and a thin-film electrode disposed within the insulating layer. The thin-film electrode of the electrostatic chuck 16 is electrically connected to a DC power supply 22 via a switch 23. The electrostatic chuck 16 generates electrostatic power using the DC voltage of the DC power supply 22. The electrostatic chuck 16 uses the generated electrostatic power to attract and hold the substrate W.

[0158] When the substrate processing apparatus 10 is operating, an edge ring FR is disposed on and around the second plate 18b in a manner that surrounds the outer periphery of the substrate W and the electrostatic chuck 16. The edge ring FR has the function of improving the uniformity of processing. The edge ring FR is formed, for example, from silicon.

[0159] A flow path 24 is formed within the second plate 18b. A heat exchange medium, such as a refrigerant, for temperature control, is supplied to the flow path 24 from a temperature control unit (e.g., a cooling unit) located outside the chamber 12. The temperature control unit regulates the temperature of the heat exchange medium. The heat exchange medium is supplied from the temperature control unit to the flow path 24 via pipe 26a. The heat exchange medium supplied from the temperature control unit to the flow path 24 via pipe 26a then returns to the temperature control unit via pipe 26b. After being regulated by the temperature control unit, the heat exchange medium returns to the flow path 24 within the substrate support 14. In this way, the temperature of the substrate support 14, i.e., the temperature of the substrate W, can be regulated.

[0160] The substrate processing apparatus 10 also includes a gas supply line 28 extending through the substrate support stage 14 to the upper surface of the electrostatic chuck 16. A heat exchange gas, such as helium (He), is supplied from the 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. This facilitates heat exchange between the substrate support stage 14 and the substrate W.

[0161] Alternatively, the heater HT can also be disposed within the substrate support 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 the heater power supply HP. By supplying power to the heater HT through the heater power supply HP, the temperature of the substrate support 14, and thus the temperature of the substrate W, can be adjusted.

[0162] The lower electrode 18 of the substrate support stage 14 is connected to a high-frequency (RF) power supply 30 via a matching adapter 32. RF current can be supplied to the lower electrode 18 from the RF power supply 30. The RF power supply 30 generates RF power that attracts ions to the substrate W mounted on the substrate support stage 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, for example, in the range of 400 kHz to 40.68 MHz. In one example, the frequency of the RF current is 13.56 MHz.

[0163] The substrate processing apparatus 10 also includes a shield 34 detachably mounted on the inner wall of the chamber 12. The shield 34 is configured to surround the outer periphery of the support mechanism 13. The shield 34 prevents the adhesion of byproducts generated during processing to the chamber 12. The shield 34 may be an aluminum component coated with ceramic such as Y2O3.

[0164] An exhaust passage is formed between the substrate support 14 and the sidewall of the chamber 12. The exhaust passage 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 regulating unit, a vacuum pump such as a turbomolecular pump (TMP), etc. A baffle 40 is disposed within the exhaust passage, i.e., between the substrate support 14 and the sidewall of the chamber 12. The baffle 40 has a plurality of through holes extending through the baffle 40 in the thickness direction. The baffle 40 can be an aluminum component with a surface coated with ceramic such as Y2O3.

[0165] An opening is formed on the upper side of chamber 12. The opening can be closed by window 42. Window 42 is formed of a dielectric such as quartz. Window 42 is, for example, a flat plate.

[0166] An air intake 12i is formed on the side wall of chamber 12. The air intake 12i is connected to a gas supply unit 44 via a pipe 46. The gas supply unit 44 supplies various gases for processing into space 12c. The gas supply unit 44 includes multiple gas sources 44a, multiple flow controllers 44b, and multiple valves 44c. Although Figure 8 It is not explicitly stated in the document, but multiple different intake ports can be set up to supply each type of gas, so that the gases do not mix together.

[0167] Multiple gas sources 44a include gas sources for various gases described later. More than one gas can be supplied to a single gas source. Multiple flow controllers 44b can be mass flow controllers (MFCs), which control flow through pressure control. Each gas source in the multiple gas sources 44a is connected to the intake port 12i via a corresponding flow controller in the multiple flow controllers 44b and a corresponding valve in the multiple valves 44c. The location of the intake port 12i is not particularly limited. For example, the intake port 12i can be formed not only on the side wall of the chamber 12 but also inside the window 42.

[0168] An opening 12p is formed in the side wall of the chamber 12. The opening 12p serves as a passage for the substrate W to be fed into the chamber 12 from the outside and out of the chamber 12 from the space 12c. A gate valve 48 is provided on the side wall of the chamber 12 to open and close the opening 12p.

[0169] An antenna 50 and a shielding member 60 covering the antenna 50 are disposed on the chamber 12 and the window 42. The antenna 50 and the shielding member 60 are disposed on the outside of the chamber 12 and the upper part of 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 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, or stainless steel.

[0170] Inner antenna element 52A and outer antenna element 52B are connected to RF power supply 70A and RF power supply 70B, respectively. Inner antenna element 52A and outer antenna element 52B receive electrical power supplies of the same or different frequencies from RF power supply 70A and RF power supply 70B, respectively. When RF power supply 70A supplies RF power to antenna 50, an induced magnetic field is generated in space 12c, which excites the processing gas in space 12c to generate plasma above substrate W.

[0171] The substrate processing apparatus 10 also includes a controller 80. The controller 80 can be a computing device having a storage unit such as a processor and memory, an input unit, and a display. The controller 80 operates based on control programs and scheme data stored in the storage unit, controlling various parts of the substrate processing apparatus 10. For example, the controller 80 controls multiple flow controllers 44b, multiple valves 44c, an exhaust device 38, RF power supplies 70A and 70B, an RF power supply 30, a matching unit 32, a heater power supply HP, etc. In the substrate processing method of the prior embodiment, the controller 80 can control various parts of the substrate processing apparatus 10 based on the aforementioned control programs and scheme data.

[0172] (Effects of the implementation method)

[0173] The substrate processing method according to the embodiments described above includes steps a, b, and c. Step a is the step of providing a substrate having an etched film and a mask formed on the etched film. Step b is the step of forming a protective film on the upper part of the opening of the mask. Step c is the step of etching the mask while suppressing the change in the opening size at the upper part of the opening with the protective film, so that the size change of the lower part of the opening not covered by the protective film is achieved. Therefore, according to the embodiments, it is possible to suppress shape abnormalities of the pattern formed on the substrate.

[0174] Alternatively, in the substrate processing method of the embodiment, step c may involve expanding the dimension of the lower part of the opening not covered by the protective film in at least one of the lateral and longitudinal directions. Therefore, according to the embodiment, when a tapered shape is formed from the upper side to the lower side of the opening, the lateral dimension of the bottom can be expanded.

[0175] Alternatively, in the substrate processing method of the embodiment, step b may involve forming a protective film using any one or a combination of chemical vapor deposition (CVD), physical vapor deposition (PVD), and atomic layer deposition (ALD). Alternatively, if step b forms a larger portion of the protective film on the upper side of the opening's sidewall compared to the lower sidewall, it may involve forming a protective film using either CVD or subconformal ALD, or a combination of multiple processes including at least one of these. If the protective film is formed to an equal degree on both the upper and lower sidewalls of the opening, it may be formed using ALD. Therefore, the thickness of the protective film can be freely controlled.

[0176] Furthermore, in the substrate processing method of this embodiment, step b includes steps b-1 and b-2. Step b-1 is the step of supplying a first reactant, causing the first reactant to adsorb onto the sidewall of the opening. Step b-2 is the step of supplying a second reactant, causing the first reactant to react with the second reactant to form a film. Step b-1 ends before the first reactant adsorbs onto the entire sidewall of the opening, or step b-2 ends before the second reactant forms a film on the entire sidewall of the opening.

[0177] Furthermore, in the substrate processing method of this embodiment, steps b and c are repeatedly performed. Therefore, by appropriately forming and etching the protective film in accordance with the state of the opening, the shape of the opening can be controlled.

[0178] Additionally, the substrate processing method of the embodiment may also include step d. Step d is a step of further etching the etched film following step c.

[0179] Alternatively, in the substrate processing method of the embodiment, the mask may include any one of an amorphous carbon layer (ACL), a spin-coated carbon (SOC) film, and a metal film. This allows the substrate processing method of the embodiment to be used in the formation of HARCs for DRAM and 3D NAND, etc.

[0180] Furthermore, the substrate processing apparatus of the embodiment includes a chamber, a stage, a gas supply unit, and a control unit. The chamber provides processing space. The stage is disposed inside the chamber. The substrate to be processed is placed on the stage. The gas supply unit supplies processing gas to the interior of the chamber. The control unit causes each part of the substrate processing apparatus to perform a substrate processing method. The substrate processing method includes steps a, b, and c. Step a is the step of providing a substrate having an etched film and a mask formed on the etched film. Step b is the step of forming a protective film on the upper part of the opening of the mask. Step c is the step of etching the mask while suppressing changes in the opening size at the upper part of the opening using the protective film, causing changes in the size of the lower part of the opening not covered by the protective film.

[0181] The embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. The above embodiments can be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

Claims

1. A method of processing a substrate, characterized by, comprising: step a, providing a substrate having an etched film and a mask formed on the etched film, wherein the mask has an opening divided by a side wall; step b, forming a protective film covering an upper portion of the side wall of the mask and not covering a lower portion of the side wall of the mask; step c, etching the mask while suppressing variation in the opening size of the upper portion of the side wall of the mask with the protective film, expanding the size of the lower portion of the side wall of the mask, and forming the shape of the opening of the mask into a shape gradually expanding in a lateral direction as it goes from the upper portion side to the lower portion side; and step d, etching the etched film through the mask etched in the step c.

2. The substrate processing method according to claim 1, wherein: the step c expands the size of the lower portion of the side wall not covered by the protective film in the lateral and longitudinal directions.

3. The substrate processing method according to claim 1 or 2, wherein: the step b forms the protective film by any one of Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), and Atomic Layer Deposition (ALD), or a combination of a plurality of processes including at least one of them.

4. The substrate processing method according to claim 1 or 2, wherein: the step b forms the protective film by any one of CVD and sub-conformal ALD, or a combination of a plurality of processes including at least one of them.

5. The substrate processing method according to claim 4, wherein: the step b includes: step b-1, supplying a first reactant to cause the first reactant to adsorb to the side wall of the opening; and step b-2, supplying a second reactant to cause the first reactant to react with the second reactant to form a film, the step b-1 ends before the first reactant adsorbs to the entire surface of the side wall of the opening, or the step b-2 ends before the second reactant forms a film to the entire surface of the side wall of the opening.

6. The substrate processing method according to claim 1 or 2, wherein: the steps b and c are repeatedly performed.

7. The substrate processing method according to claim 1 or 2, comprising a step d of further etching the etched film after the step c.

8. The substrate processing method according to claim 1 or 2, wherein: the mask includes any one of an Amorphous Carbon Layer (ACL), a Spin-On Carbon (SOC) film, and a metal film. comprising:

9. A substrate processing apparatus, characterized by, a chamber; a substrate support table provided inside the chamber; a gas supply portion for supplying a processing gas to the inside of the chamber; a plasma generation portion; and a control portion, the control portion executes a substrate processing method including: step a, accepting a substrate having an etched film and a mask formed on the etched film, wherein the mask has an opening divided by a side wall; ​ ​ Step b, forming a protective film covering an upper portion of the side wall of the mask and not covering a lower portion of the side wall of the mask; Step c, etching the mask while suppressing variation in the opening size of the upper portion of the side wall of the mask with the protective film, expanding the size of the lower portion of the side wall, and forming the shape of the opening of the mask into a shape that gradually expands in the lateral direction as it goes from the upper portion side to the lower portion side; and Step d, etching the etched film through the mask etched in the step c.

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