Etching method and etching apparatus

Abstract

The present application relates to an etching method and an etching apparatus, which improve the shape of a pattern formed by etching or the uniformity of the shape within the substrate surface. The etching method includes: step a), step b), step c), step d), and step e). Step a) is a step of providing a substrate having an etched film onto a stage. Step b) is a step of locally etching the etched film to form a recess. Step c) is a step of setting the temperature of the stage to a first temperature and forming a first film having a first film thickness distribution on the sidewall of the recess. Step d) is a step of further locally etching the etched film on which the first film is formed. Step e) is a step of setting the temperature of the stage to a second temperature different from the first temperature and forming a second film having a second film thickness distribution different from the first film thickness distribution on the sidewall of the recess.

Description

Technical Field

[0001] The following disclosure relates to an etching method and an etching apparatus. Background Art

[0002] As the integration of semiconductor devices proceeds not only in the horizontal direction but also in the vertical direction, the aspect ratio of the patterns formed in the manufacturing process of semiconductor devices has become higher. For example, in the manufacture of 3D NAND, channel holes are formed in the direction penetrating through many metal wiring layers. When forming 64-layer memory cells, the aspect ratio of the channel holes is also 45.

[0003] In order to form high-aspect-ratio patterns with high precision, various methods have been proposed. For example, a technique for controlling the size of a pattern formed by etching a semiconductor at the nanoscale has been proposed (Patent Document 1). In this technique, a film formed by self-assembled monolayer (SAM) or atomic layer deposition (ALD) is used as a passivation layer. After forming the passivation layer on the sidewalls of the recesses formed in the substrate, etching is performed, thereby achieving highly precise anisotropic etching.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: U.S. Patent Application Publication No. 2010 / 0173494 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] The present disclosure can improve the shape of a pattern formed by etching or the uniformity of the shape within the substrate surface.

[0009] Solutions to the Problems

[0010] The etching method according to one aspect of the present disclosure includes: step a), step b), step c), step d), and step e). Step a) is a step of providing a substrate having an etching target film onto a stage. Step b) is a step of locally etching the etching target film to form a recess. Step c) is a step of setting the temperature of the stage to a first temperature and forming a first film having a first film thickness distribution on the sidewall of the recess. Step d) is a step of further locally etching the etching target film on which the first film is formed. Step e) is a step of setting the temperature of the stage to a second temperature different from the first temperature and forming a second film having a second film thickness distribution different from the first film thickness distribution on the sidewall of the recess.

[0011] Advantageous Effects of the Invention

[0012] According to the present disclosure, it is possible to improve the shape of a pattern formed by etching or the uniformity of the shape within the substrate surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a flowchart showing an example of the process flow of the etching method of the first embodiment.

[0014] Figure 2A is a first diagram for explaining an example of a pattern formed by the etching method of the first embodiment.

[0015] Figure 2B is a second diagram for explaining an example of a pattern formed by the etching method of the first embodiment.

[0016] Figure 2C is a third diagram for explaining an example of a pattern formed by the etching method of the first embodiment.

[0017] Figure 2D is a fourth diagram for explaining an example of a pattern formed by the etching method of the first embodiment.

[0018] Figure 3A is a graph showing the experimental results under the first temperature condition.

[0019] Figure 3B is a graph showing the experimental results under the second temperature condition.

[0020] Figure 4 is to Figure 3A and Figure 3B The experimental results are summarized in a graph.

[0021] Figure 5 is a diagram showing an example of the conditions used in the etching method of the first embodiment.

[0022] Figure 6 It is a flowchart showing an example of the process of the etching method of the second embodiment.

[0023] Figure 7A It is a diagram showing an example of the section of the stage of the etching apparatus of the second embodiment.

[0024] Figure 7B It is a diagram showing another example of the section of the stage of the etching apparatus of the second embodiment.

[0025] Figure 7C It is a diagram showing yet another example of the section of the stage of the etching apparatus of the second embodiment.

[0026] Figure 8 It is a diagram showing an example of the conditions in the etching method of the second embodiment.

[0027] Figure 9A It is a diagram for explaining an example of the shape correction achieved by the etching method of the second embodiment.

[0028] Figure 9B It is a diagram for explaining another example of the shape correction achieved by the etching method of the second embodiment.

[0029] Figure 10 It is a diagram showing an example of the etching apparatus of one embodiment. Detailed Embodiment

[0030] Hereinafter, the disclosed embodiments will be described in detail based on the drawings. It should be noted that this embodiment is not restrictive. In addition, the embodiments can be appropriately combined within the range where the processing contents do not conflict. It should be noted that in each drawing, the same or corresponding parts are denoted by the same reference numerals.

[0031] Hereinafter, in the description of the embodiment, when explaining the direction of the pattern formed on the substrate, the direction substantially perpendicular to the substrate surface is referred to as the thickness direction or the longitudinal direction. In addition, the direction substantially parallel to the substrate surface is referred to as the lateral direction. In the case where the substrate is substantially disk-shaped, the direction parallel to the substrate surface from the center of the disk toward the circumference is also referred to as the radial direction.

[0032] In the following description, a "pattern" refers to the overall shape formed on a substrate. The pattern refers to holes, trenches, line and space, masks, and the overall shape of a plurality of shapes formed on the substrate. In addition, a "recess" refers to a portion of the shape that is recessed in the thickness direction of the substrate in the pattern formed on the substrate. In addition, the recess has a "sidewall" that is the inner peripheral surface of the recessed shape, a "bottom" that is the bottom portion of the recessed shape, and a "top" that is the surface of the substrate near the sidewall and is continuous with the sidewall. In addition, the space surrounded by the corners of the top is called an "opening". It should be noted that the term "opening" is also used to refer to the entire space surrounded by the bottom and sidewalls of the recess or any position in the space.

[0033] (Shape anomalies generated in semiconductor processes)

[0034] It is known that shape anomalies occur during etching to form a pattern with a high aspect ratio. For example, when forming a recess in the longitudinal direction (film thickness direction), sometimes a shape anomaly occurs where the inner peripheral surface of the recess bulges laterally. Such a shape anomaly is called bowing.

[0035] The position where bowing occurs is mostly directly below the position where the type of film formed on the substrate changes. For example, when a layer that becomes a mask during etching is stacked on the etched film to be etched, the etching rate is different between the mask and the etched film. Therefore, the etching amount increases at the position where the mask is switched to the etched film, and the opening often bulges laterally directly below the mask.

[0036] In addition, bowing sometimes also occurs at a position close to the bottom of the recess formed on the substrate. It is considered that this is because, in the case where the shape of the mask is deformed, etc., ions bounce back in the recess and collide with the sidewall of the recess, over-etching the sidewall.

[0037] In addition, in addition to bowing, a taper in which the pattern gradually becomes smaller in the depth direction also occurs. It is considered that this is because the etchant is less likely to reach the deeper part of the pattern than the shallower part of the pattern. To suppress this shape anomaly, it is ideal to be able to control the position and thickness of the protective film formed.

[0038] (An example of the process of the etching method of the first embodiment)

[0039] Figure 1 It is a flowchart showing an example of the process of the etching method of the first embodiment. The etching method of the first embodiment controls at least one of the position and thickness of the film formed on the substrate by controlling the temperature of the stage on which the substrate is placed.

[0040] First, a substrate is provided (step S100). For example, a substrate having an etched film and a mask on the etched film is provided. The substrate is transferred into a reaction chamber in which a mounting table is disposed and is mounted on the mounting table. The substrate disposed on the mounting table is subjected to a plurality of processes. Figure 1 In this case, "n" represents the number of processes and is set to "n = 1" at the start of the process.

[0041] First, local etching of the etched film is performed (step S101). By local etching, a pattern including recesses is formed on the substrate. In step 101, an etching gas is supplied into the reaction chamber to generate plasma. The etched film is etched by introducing ions in the plasma into the etched film.

[0042] Next, the temperature of the substrate and the temperature of the mounting table on which the substrate is mounted are controlled to the n-th temperature (the first temperature in the first process), and the n-th film is formed in the recesses (step S102). The n-th film has an n-th film thickness distribution corresponding to the n-th temperature. For example, in the first film formation process, the temperature of the mounting table is controlled to the first temperature. Then, the first film having the first film thickness distribution is formed. Then, local etching of the etched film on which the first film is formed is further performed (step S103).

[0043] Next, it is determined whether the number of executions has reached a preset number (step S104). In the case where it is determined that the number of executions has reached the preset number (step S104, YES), the process ends. In the case where it is determined that the number of executions has not reached the preset number (step S104, NO), the number is updated (step S105, n = n + 1), and the process returns to step S102. For example, if the preset number is 10 times and the number of executions is 1 time, the process returns to step S102 to perform the second film formation process. In the second film formation process, in step S102, the temperature of the mounting table is controlled to the second temperature, and the second film having the second film thickness distribution is formed.

[0044] After that, the process is repeated until the number of executions reaches the preset number. When the number of executions reaches the preset number, the process ends.

[0045] Figure 1In the process, one-time processing may also include processes other than the film formation process (step S102) and the etching process (step S103). For example, in addition to the etching process of step S103, the etching process may be performed under processing conditions different from those of step S103. In addition, in addition to the film formation process of step S102, the film formation process may be performed under processing conditions different from those of step S102. In addition, the etching process of step S103 and the film formation process of step S102 may each include more than one process. For example, in step S103, the etching process under the same or different processing conditions may be repeatedly performed multiple times. In addition, in step S102, the film formation process under the same or different processing conditions may be repeatedly performed multiple times.

[0046] It should be noted that in Figure 1 the example, the number of executions is set to a preset number. However, it is not limited thereto. The pattern shape may be measured after the film formation in step S102, and whether to perform the next process and the temperature of the stage may be determined based on the measurement result. When the number of executions is preset, the number of times of the etching process (step S103) required to reach the desired etching depth may be calculated and set.

[0047] (An example of a pattern formed in one embodiment)

[0048] Figures 2A - 2D is a diagram for explaining an example of a pattern formed by the etching method of one embodiment.

[0049] Figure 1 The film formation process of step S102 of Figures 2A - 2D is performed using unsaturated ALD, for example. Before explaining

[0050] ALD generally includes four processing steps. First, a first reactant (also called a precursor) is introduced into a reaction chamber in which a substrate is disposed. The first material contained in the first reactant is adsorbed on the surface of the substrate. After the surface is covered with the first material, the reaction chamber is evacuated. Next, a second reactant (also called a reaction gas) containing a second material that reacts with the first material is introduced into the reaction chamber. The second material reacts with the first material on the substrate to form a film. The film formation is completed by the reaction with the first material on the surface. ALD forms a film by self-controlled adsorption and reaction of a predetermined material with a substance pre-existing on the substrate surface. Therefore, ALD generally achieves conformal film formation by setting a sufficient processing time.

[0051] In contrast, unsaturated ALD uses processing conditions in such a way that self-controlled adsorption or reaction on the surface of the substrate is not completed. As processing schemes, there are at least the following two schemes.

[0052] (1) Adsorb the precursor on the entire surface of the substrate. Control the reactant introduced later so that it does not cover the entire surface of the substrate.

[0053] (2) Adsorb the precursor only on a part of the surface of the substrate. The reactant introduced later forms a film only on the surface part where the precursor is adsorbed.

[0054] The etching method of the first embodiment controls the position and thickness of the film formed on the sidewall of the recess by using the method of (1).

[0055] Figure 2A It shows a state in which recesses 200 are formed in the first layer 101 and the second layer 102 thereon on the substrate 100 by the local etching in step S101. In Figure 2A 's example, the first layer 101 is the film to be etched. The second layer 102 is a mask in the etching of the first layer 101. The recess 200 has a bottom 200B, sidewalls 200S, and a top 200T.

[0056] In Figure 2A , the recess 200 is a tapered shape that gradually tapers from below the second layer 102. If etching continues in the state of Figure 2A , lateral etching occurs and bowing is generated. Therefore, in the first embodiment, an unsaturated ALD is used to form a protective film on the sidewalls of the locally etched recesses 200, suppressing the generation of bowing caused by etching.

[0057] First, introduce the precursor P into the reaction chamber in which the substrate is disposed. Set a sufficient time for the adsorption of the precursor P, whereby the precursor P is adsorbed on the entire surface of the substrate ( Figure 2B ). Here, for the adsorption of the precursor P, a plasma of the precursor P may or may not be generated. When the adsorption of the precursor P is completed, the reaction chamber is purged. Then, introduce the reactant R into the reaction chamber and make the reactant R react with the precursor P adsorbed on the surface of the substrate. Regarding the reaction of the reactant R with the precursor P, a reaction gas containing the reactant R may be introduced into the reaction chamber, or a plasma of the reactant R may be generated to react with the precursor P ( Figure 2C ). The introduced reactant R reacts with the precursor P on the substrate and gradually forms a protective film 300 from above the second layer 102 (refer to Figure 2D ). Here, before the formation of the protective film 300 reaches the bottom 200B of the recess 200, the reactant R is purged. By such treatment, using the ALD method, and not forming the protective film 300 on the entire sidewalls 200S of the recess 200, but only forming the protective film 300 on the upper part of the first layer 101 and the second layer 102 ( Figure 2C ). By repeatingFigure 2A , Figure 2B , Figure 2C The treatment shown can obtain Figure 2D the shape shown.

[0058] It should be noted that in the example of Figures 2A - 2D , unsaturated ALD is achieved by not allowing the reactant R to reach the bottom 200B of the recess 200. In other examples, alternatively, unsaturated ALD can be achieved by not allowing the precursor P to reach the bottom 200B of the recess 200 (not allowing the precursor P to adsorb to the bottom 200B of the recess 200).

[0059] (Treatment conditions for selective adsorption and reaction)

[0060] As described above, in the etching method of the first embodiment, the treatment conditions are adjusted so that the adsorption of the precursor or the reaction of the reactant occurs at a specified portion of the pattern. In one embodiment, the treatment conditions are adjusted such that the adsorption of the precursor or the reaction of the reactant occurs only at the top and the upper sidewall of the recess.

[0061] Examples of the treatment conditions that can be adjusted to implement the above etching method include the temperature of the stage on which the substrate is placed, the pressure in the reaction chamber, the flow rate and introduction time of the introduced precursor, the flow rate and introduction time of the introduced reactant, the treatment time of each process, etc. In addition, in the case of a treatment using plasma, the value of the high-frequency (RF) power applied to generate the plasma can also be adjusted.

[0062] Here, focusing on the temperature of the stage, the position and thickness of the formed film are controlled.

[0063] (Adjustment of film thickness and film formation position achieved based on temperature control)

[0064] Figure 3A is a graph showing the experimental results under the first temperature condition. Figure 3B is a graph showing the experimental results under the second temperature condition.

[0065] In the Figure 3A and Figure 3B experiments shown, a treatment consisting of four steps of precursor introduction, purge, reactant introduction, and purge was performed 35 times. In the introduction of the reactant, the reactant was made into plasma. A silicon-containing gas was used as the precursor, and oxygen diluted with argon was used as the reactant. The formed protective film was a silicon oxide film. In this experiment, the temperature of the stage at the time of introducing the reactant was set to two kinds, and the thickness and position of the formed film were measured. The temperature of the stage was adjusted to 10 °C for the Figure 3A experiment, and the temperature of the stage was adjusted to 60 °C for the Figure 3Bexperiments. In addition, the introduction time of the reactants (the generation time of the plasma) was set to four values: 1 second, 4 seconds, 10 seconds, and the saturation completion time (sufficient time for the reactants to saturate on the substrate surface).

[0066] In Figure 3A and Figure 3B , on the horizontal axis, the opening size (CD: Critical Dimension) of the formed recesses is represented in nanometers [nm] units, and on the vertical axis, the depth of the recesses is represented in micrometers [μm] units. In each figure, "Initial" represents the opening size of the recesses before the start of the experiment, and "Conformal" represents the opening size when the treatment is carried out until the saturation completion time. According to Figure 3A and Figure 3B , it can be seen that in the "Conformal" case, a film is formed with a substantially uniform thickness regardless of the depth of the recesses.

[0067] Next, the thickness of the film formed by changing the introduction time of the reactants was measured. According to Figure 3A 's curve graph, regarding the state of the film formed when the introduction time of the reactants is set to 10 seconds, although the film thickness slightly decreases downward, it is substantially conformal. In addition, when the introduction time of the reactants is set to 4 seconds, there is a difference in the thickness of the formed film compared to the case of 10 seconds, and a thinner film than in the case of 10 seconds is formed at the lower part of the side wall of the recess. When set to 1 second, a film with a thickness gradually decreasing from top to bottom is formed at a position from the top of the recess to about 0.6 μm, but almost no film is formed in the part below 0.6 μm.

[0068] On the other hand, when observing the Figure 3B curve graph with the temperature of the stage set to 60 °C, regarding the state of the film formed when the introduction time of the reactants is set to 10 seconds, although the film thickness slightly decreases downward, it is substantially conformal. When the introduction time of the reactants is set to 4 seconds, there is a difference in the thickness of the formed film compared to the case of 10 seconds, and a thinner film than in the case of 10 seconds is formed at the lower part of the side wall of the recess. When set to 1 second, a film with a thickness gradually decreasing from top to bottom is formed at a position from the top of the recess to about 1 μm, but almost no film is formed in the part below 1 μm.

[0069] If the introduction time is shortened, a film with a thickness gradually decreasing in the film thickness direction of the pattern can be formed in any case. In particular, when the introduction time is set to 1 second, if the temperature of the stage is controlled to 10 °C, film formation at positions below 0.6 μm can be suppressed, and if controlled to 60 °C, film formation at positions below 1 μm can be suppressed. Thus, according to Figure 3A and Figure 3BAs can be seen from the experimental results shown, by changing the temperature of the stage, the thickness and distribution of the formed film can be adjusted.

[0070] Figure 4 is a graph summarizing the experimental results of Figure 3A and Figure 3B . Specifically, Figure 4 is obtained by superimposing the experimental results on a graph showing the correspondence between the saturation time of oxygen (O2) plasma calculated using a diffusion equation, etc. and the aspect ratio.

[0071] As Figure 4 shown, the lower limit position (A / R: aspect ratio) where the film is formed changes corresponding to the change in the introduction time of the reactant (here, the irradiation time of O2 plasma). In addition, when the temperature of the stage is set to 10°C and 60°C, there is a difference in aspect ratio of about 20 for the lower limit position where the film is formed ( Figure 4 the part indicated by the arrow in

[0072] Therefore, the etching method of the first embodiment forms a protective film in a region where shape anomalies such as bowing and tapering are likely to occur, based on previously observing the positions where such shape anomalies occur. In addition, the etching method of the first embodiment adjusts the film-forming region by adjusting the temperature of the stage on which the substrate is placed. In addition, in the etching method of the first embodiment, if an unsaturated ALD is used to form a film, a film with a gradually decreasing film thickness in the film thickness direction can be formed. Therefore, according to the first embodiment, a protective film can be formed in a region (position) corresponding to shape anomalies such as a tapered shape and bowing.

[0073] (Temperature control example)

[0074] It should be noted that in Figure 1 , for ease of explanation, it is assumed that the set temperature of the stage in the film-forming process (step S102) is changed in the order of the first temperature and the second temperature. Among them, the set temperature of the stage can be changed for each film-forming process, or it can remain unchanged. The set temperature of the stage can be the same in multiple film-forming processes. That is, according to the shape of the formed concave portion and the processing conditions, the first temperature and the second temperature can be the same, or the first temperature can be higher or lower than the second temperature.

[0075] For example, in the case of suppressing a shape anomaly such as a tapered shape where the opening of the concave portion narrows from the upper part to the bottom, a protective film with a decreasing film thickness from the upper part to the bottom is formed. By increasing the aspect ratio of the concave portion, when forming the protective film ( Figure 1The temperature of the stage in step S102) increases, which can move the film formation region of the protective film downward.

[0076] In addition, for example, when the bowing occurs above the concave portion, the temperature of the stage during the formation of the protective film is lowered. Thereby, the position where the bowing occurs can be covered with the protective film. In addition, for example, when the bowing occurs near the bottom of the concave portion, it is sufficient to increase the temperature of the stage during the formation of the protective film.

[0077] In this way, by previously determining the position where the shape abnormality occurs and forming the protective film at the thickness and position corresponding to the abnormality, the shape of the pattern can be improved.

[0078] Figure 5 It is a diagram showing an example of the conditions used in the etching method of the first embodiment. In Figure 5 the example, as conditions, "number of times", "stage temperature", and "processing conditions" are set. "Number of times" represents the number of times of processing, that is, which time of processing. "Stage temperature" represents the set temperature of the stage during the film formation process ( Figure 1 , step S102)) corresponding to the number of times. "Processing conditions" represent the processing conditions other than the stage temperature. The processing conditions are, for example, the types and flow rates of the precursor and the reactant, the pressure in the reaction chamber, etc. In Figure 5 the example, when the number of times is 1 to 10, the temperature of the stage is set to 10 °C, when the number of times is 11 to 20, the temperature of the stage is set to 20 °C, and when the number of times is 21 to 30, the temperature of the stage is set to 30 °C. Figure 5 The example is a condition for gradually moving the position where the protective film is formed downward by increasing the temperature of the stage as the processing progresses. It should be noted that the temperature conditions used in the etching method of the first embodiment are not particularly limited. For example, conditions where the temperature of the stage temporarily increases and then decreases as the processing progresses can be used, or conditions where the temperature of the stage gradually decreases can be used.

[0079] (Effect of the First Embodiment)

[0080] The etching method of the first embodiment described above includes: step a), step b), step c), step d), and step e). Step a) is a step of providing a substrate having an etched film onto a mounting table. Step b) is a step of locally etching the etched film to form a recess. Step c) is a step of setting the temperature of the mounting table to a first temperature and forming a first film having a first film thickness distribution on the sidewall of the recess. Step d) is a step of further locally etching the etched film on which the first film is formed. Step e) is a step of setting the temperature of the mounting table to a second temperature different from the first temperature and forming a second film having a second film thickness distribution different from the first film thickness distribution on the sidewall of the recess. Therefore, the method of the first embodiment can form a first film having a first film thickness distribution corresponding to the first temperature and a second film having a second film thickness distribution corresponding to the second temperature. Therefore, according to the first embodiment, the film thickness distribution of the formed film can be adjusted according to the temperature. Therefore, the shape of the pattern formed by etching the semiconductor can be improved.

[0081] In addition, in the first embodiment, the first temperature is different from the second temperature. In addition, the first temperature may be a temperature lower than the second temperature. In addition, the first temperature may also be a temperature higher than the second temperature. Therefore, according to the first embodiment, the temperature can be adjusted according to the shape of the pattern formed by etching the semiconductor to adjust the film thickness distribution. In addition, according to the first embodiment, a protective film can be formed in an area where the shape of the pattern may be abnormal due to etching.

[0082] In addition, in the first embodiment, in addition to or instead of the temperature of the mounting table, the film thickness distribution can also be adjusted by adjusting other processing conditions. For example, the above step c) may include step c-1) and step c-2). Step c-1) is a step of supplying a first reactant and adsorbing the first reactant on the sidewall of the recess. Step c-2) is a step of supplying a second reactant and reacting the first reactant with the second reactant to form a film. In addition, the above step e) may include step e-1) and step e-2). Step e-1) is a step of supplying a third reactant and adsorbing the third reactant on the sidewall of the recess. Step e-2) is a step of supplying a fourth reactant and reacting the third reactant with the fourth reactant to form a film. And by making the length of the processing time of step c-2) different from the length of the processing time of step e-2), at least one of the thickness and position of the formed film can be further changed. By adjusting the processing conditions in this way, the shape of the pattern formed by etching the semiconductor can be further improved.

[0083] In addition, in the first embodiment, the first film thickness distribution is a distribution in which the film thickness changes in the thickness direction of the substrate. Therefore, according to the first embodiment, by adjusting the film thickness distribution in the thickness direction of the substrate, the shape of the pattern formed by etching the semiconductor can be improved.

[0084] In addition, in the first embodiment, the film to be etched is the film to be etched in processes b) and d), and may include a mask on the film to be etched. In addition, the film to be etched may be a silicon-containing layer. The silicon-containing film may be a silicon-containing dielectric film. An example includes a silicon oxide film (SiO x ). In addition, the mask on the film to be etched may be a carbon-containing mask or a metal-containing mask. In addition, the film to be etched and the mask may be silicon-containing films having different compositions from each other.

[0085] In addition, in the first embodiment, processes b), c), d), and e) may be repeated until the aspect ratio of the concave portion becomes at least 40. Therefore, the aspect ratio of the concave portion can be adjusted according to the type of semiconductor device to be manufactured and the process applying the first embodiment.

[0086] (Second Embodiment)

[0087] In the above first embodiment, the position and thickness of the formed protective film are adjusted by changing the temperature of the stage set for each film formation process. Not limited thereto, the temperature of the stage may also be changed within the plane of the stage. As a second embodiment, an example of film formation with a temperature difference within the plane of the stage will be described.

[0088] Figure 6 FIG. is a flowchart showing an example of the process flow of the etching method of the second embodiment. First, a substrate is provided (step S200). For example, a substrate having a film to be etched and a mask on the film to be etched is provided. The substrate is carried into a reaction chamber in which a stage is disposed and placed on the stage. The substrate placed on the stage is subjected to a plurality of processes. Figure 6 In this case, the number of processes is represented by "n", and is set to "n = 1" at the start of the process. The process of step S200 is the same as Figure 1 step S100 of

[0089] Then, the film to be etched is locally etched (step S201, local etching), and a pattern including a concave portion is formed on the substrate.

[0090] Next, control the temperature of the substrate and the temperature of the stage on which the substrate is placed. Control at least two of the plurality of zones of the stage to different temperatures, and form a film (protective film) in the recess (step S202). The film has different film thickness distributions corresponding to the respective controlled temperatures of the zones of the stage. For example, the first film thickness distribution of the first film formed in the first zone controlled to a relatively high temperature is different from the second film thickness distribution of the second film formed in the second zone controlled to a relatively low temperature. For example, the lower limit of the position where the first film is formed is lower than the lower limit of the position where the second film is formed. Then, further perform local etching on the etched film on which the first film and the second film are formed (step S203).

[0091] Next, determine whether the number of executions has reached a preset number (step S204). If it is determined that the number of executions has reached the preset number (step S204, Yes), end the process. The preset number is 1 or more. If it is determined that the number of executions has not reached the preset number (step S204, No), update the number (step S205, n = n + 1), return to step S202, and perform the film forming process. In the (n + 1)-th film forming process, the temperature group of the plurality of zones of the stage may be set to a temperature group different from that of the n-th time. The temperature group refers to the temperature combination when setting the temperature for each of the plurality of zones.

[0092] After that, repeat the process until the number of executions reaches the preset number. When the number of executions reaches the preset number, end the process.

[0093] (Zones capable of controlling temperature)

[0094] Thus, in the second embodiment, the set temperature of the stage in each film forming process is not one but multiple. In addition, the multiple set temperatures correspond to the multiple zones of the stage. Next, the zones of the stage will be described.

[0095] In the second embodiment, in order to vary the temperature of the stage within the plane of the stage, the stage surface is divided into a plurality of zones capable of independently controlling the temperature. Then, heaters corresponding to the respective zones are arranged in the stage.

[0096] It should be noted that the number and shape of the zones capable of independently controlling the temperature are not particularly limited. For example, the circular stage surface can be divided into a plurality of zones in a concentric circle shape. Furthermore, each of the zones can be divided into a plurality of zones in the circumferential direction. In addition, when dividing each of the zones in the circumferential direction, the number of divisions can be the same or different. In addition, when dividing each of the zones in the circumferential direction, the dividing positions can be the same or different in the circumferential direction.

[0097] Figures 7A - 7CThis is a diagram showing an example of the sections of the stage of the etching apparatus according to the second embodiment. In the second embodiment, a plurality of sections capable of independently controlling the temperature are provided in advance on the stage.

[0098] Figure 7A The stage 11A shown is divided into three sections. The first section Z1 corresponds to the central portion of the substrate. The second section Z2 corresponds to the edge portion of the substrate. The third section Z3 corresponds to the annular portion between the central portion and the edge portion of the substrate. The sizes of the first section Z1, the second section Z2, and the third section Z3 are not particularly limited.

[0099] Figure 7B The stage 11B shown is divided into fourteen sections. The stage 11B is divided into four concentric circles from the center to the circumference. The circular first section Z1 is located in the center. Around the first section Z1, the second section Z2, the third section Z3, the fourth section Z4, and the fifth section Z5 are arranged in a form that divides the ring into four equal parts. Further, around the second section Z2 to the fifth section Z5, eight sections are arranged. The eight sections are the sixth section Z6, the seventh section Z7, the eighth section Z8, the ninth section Z9, the tenth section Z10, the eleventh section Z11, the twelfth section Z12, and the thirteenth section Z13. Further, around the sixth section Z6 to the thirteenth section Z13, an annular fourteenth section Z14 is arranged.

[0100] Figure 7C The stage 11C shown is also divided into fourteen sections. The stage 11C is divided into four in the radial direction and further divided in the circumferential direction. The first section Z1 is the central circular part. The annular part surrounding the first section Z1 is divided into four in the circumferential direction, namely the second section Z2, the third section Z3, the fourth section Z4, and the fifth section Z5. The second sixth section Z6 from the outermost peripheral part is not divided in the circumferential direction. The outermost peripheral part is divided into eight sections Z7 to Z14 in the circumferential direction.

[0101] Figures 7A - 7C The division of the sections of the stage shown is only an example, and it can be divided according to different schemes. In addition, the sections of the stage can be provided corresponding to the regions of the substrate. For example, a first section corresponding to the first region of the substrate and a second section corresponding to the second region of the substrate can be provided. In this case, the first region can be set as the region including the center of the substrate, and the second region can be set as the region including the edge of the substrate.

[0102] Take Figure 7A as an example to illustrate the in-plane temperature control of the stage. Figure 7AThe segment division shown is suitable for the case where a difference occurs between the central portion and the edge portion of the substrate in the state of the formed pattern. For example, in film formation processing and etching processing, sometimes due to the difference in plasma density in the etching apparatus, etc., a difference in film formation amount and etching amount occurs between the central portion and the edge portion of the substrate. In this case, the temperature of the stage at the position where the film formation amount is large is set low, and the temperature of the stage at the position where the film formation amount is small is set high.

[0103] Figure 8 It is a diagram showing an example of the conditions in the etching method of the second embodiment. In Figure 8 this example, as conditions, "condition number", "stage temperature, first segment, second segment, third segment", and "processing conditions" are set. The "condition number" is a number used to uniquely identify each condition. The "stage temperature" indicates the temperature of each segment of the stage set under the corresponding conditions. Regarding the "stage temperature", different temperatures can be set for the "first segment", "second segment", and "third segment" respectively. The "processing conditions" are processing conditions other than the stage temperature. For example, in Figure 8 this example, corresponding to the condition number "1", the stage temperature is set such that the first segment is 10°C, the second segment is 60°C, and the third segment is 30°C. In this way, it can be set such that the temperature of the stage changes from the center to the edge of the stage.

[0104] Figure 9A and Figure 9B are diagrams for explaining an example of the shape correction achieved by the etching method of the second embodiment. On the substrate 110 shown in Figure 9A , an etched film 120 and a mask 130 are successively formed. And, a recess 201 is formed by etching. The recess 201 causes bowing below the boundary between the etched film 120 and the mask 130. In addition, the recess 201 has a tapered shape that gradually narrows downward with an opening in the etched film 120. The protective film 301 is formed by the same film formation process as the etching method of the first embodiment ([[]] Figure 1 , step S102).

[0105] Figure 9B The recess 202 in Figure 9B has a larger bulge in the lateral direction caused by bowing compared to the recess 201. In addition, Figure 9A the lower end of the bowing shown in Figure 9B is located slightly lower than the lower end of the bowing shown in Figure 9AThe position of the concave portion 201 is lower. This is because, by setting a temperature difference between the temperature of the stage at the position of the concave portion 201 and the temperature of the stage at the position of the concave portion 202, the position where the protective film 301 is formed and the distribution of the film thickness are adjusted. In Figure 9A and Figure 9B In the example of, by making the temperature of the stage at the position of the concave portion 201 lower than the temperature of the stage at the position of the concave portion 202, the protective film 301 is formed in both the concave portion 201 and the concave portion 202 up to a position exceeding the lower end of their respective bows. The protective film 301 can be formed by CVD or by unsaturated ALD.

[0106] (Effect of the second embodiment)

[0107] The etching method of the above second embodiment includes: step a), step b), step c), and step d). Step a) is a step of supplying a substrate having an etched film to the stage. Step b) is a step of locally etching the etched film to form a concave portion. Step c) is a step of setting at least two of the plurality of sections of the stage to different temperatures, and forming a film having different film thickness distributions in the depth direction on the side walls of the concave portion for the at least two sections. Step d) is a step of further locally etching the etched film having the film formed thereon. In this way, by controlling the in-plane difference in the temperature of the stage, even when bowing occurs at different positions in the film thickness direction of the etched film in different regions within one substrate, etching can be performed while suppressing the bowing by forming a protective film having an appropriate distribution in each region.

[0108] (Configuration example of the etching apparatus of the embodiment)

[0109] Figure 10 is a diagram showing an example of an etching apparatus of the embodiment. Figure 10 The shown etching apparatus is a plasma processing apparatus. Figure 10 The shown plasma processing apparatus 1 includes a reaction chamber 10, a gas supply unit 20, an RF (Radio Frequency) power supply unit 30, an exhaust system 40, and a control unit 50.

[0110] In the present embodiment, the reaction chamber 10 includes a support portion 11 (also referred to as a stage) and an upper electrode showerhead assembly 12. The support portion 11 is disposed in the lower region of the processing space 10s within the reaction chamber 10. The upper electrode showerhead assembly 12 is disposed above the support portion 11 and can function as a part of the top plate of the reaction chamber 10.

[0111] The support portion 11 is configured to support the substrate W in the processing space 10s. In the present embodiment, the support portion 11 includes: a lower electrode 111, an electrostatic chuck 112, and an edge ring 113. The electrostatic chuck 112 is disposed on the lower electrode 111 and is configured to support the substrate W by the upper surface of the electrostatic chuck 112. The edge ring 113 is disposed to surround the substrate W on the upper surface of the peripheral portion of the lower electrode 111. The surface of the support portion 11 that supports the substrate W is divided into a plurality of zones that can independently control the temperature (refer to Figures 7A - 7C ). A plurality of heaters are disposed inside the support portion 11. In the example of Figure 10 , three heaters 111a, 111b, and 111c are arranged and disposed in the radial direction. The heaters 111a, 111b, and 111c respectively correspond to one zone and heat the corresponding zone. The specific shape and type of the heater are not particularly limited. The heaters 111a, 111b, and 111c are respectively connected to the temperature control units 111d, 111e, and 111f.

[0112] The upper electrode showerhead assembly 12 is configured to supply one or more processing gases from the gas supply unit 20 to the processing space 10s. In the present embodiment, the upper electrode showerhead assembly 12 includes a gas inlet 12a, a gas diffusion chamber 12b, and a plurality of gas outlets 12c. The gas inlet 12a is in fluid communication with the gas supply unit 20 and the gas diffusion chamber 12b. The plurality of gas outlets 12c are in fluid communication with the gas diffusion chamber 12b and the processing space 10s. In the present embodiment, the upper electrode showerhead assembly 12 is configured to supply one or more processing gases from the gas inlet 12a to the processing space 10s via the gas diffusion chamber 12b and the plurality of gas outlets 12c.

[0113] The gas supply unit 20 may include one or more gas sources 21 and one or more flow controllers 22. In the present embodiment, the gas supply unit 20 is configured to supply one or more processing gases from each gas source 21 to the gas inlet 12a via each flow controller 22. The flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Moreover, the gas supply unit 20 may further include one or more flow modulation devices that modulate the flow rate of one or more processing gases or pulse them.

[0114] The RF power supply unit 30 is configured to supply RF power, for example, one or more RF signals, to the lower electrode 111, the upper electrode showerhead assembly 12, or one or more electrodes such as both the lower electrode 111 and the upper electrode showerhead assembly 12. In the present embodiment, the RF power supply unit 30 includes two RF generation units 31a, 31b and two matching circuits 32a, 32b. The RF power supply unit 30 shown in the present embodiment is configured to supply a first RF signal from the first RF generation unit 31a to the lower electrode 111 via the first matching circuit 32a. The RF spectrum includes a part of the electromagnetic spectrum in the range of 3 Hz to 3000 GHz. Regarding electronic material processes such as semiconductor processes, the RF spectrum for plasma generation is preferably in the range of 100 kHz to 3 GHz, and more preferably in the range of 200 kHz to 150 MHz. For example, the first RF signal may have a frequency in the range of 27 MHz to 100 MHz. In addition, the RF power supply unit 30 shown in the present embodiment is configured to supply a second RF signal from the second RF generation unit 31b to the lower electrode 111 via the second matching circuit 32b. For example, the second RF signal may have a frequency in the range of 400 kHz to

[0115] 13.56 MHz. Instead, a direct current (DC) voltage pulse generation unit may be used instead of the second RF generation unit 31b. Also, although not shown in the drawings, other embodiments are considered here. For example, in an alternative embodiment, the RF power supply unit 30 may be configured to supply a first RF signal from an RF generation unit to the lower electrode 111, supply a second RF signal from another RF generation unit to the lower electrode 111, and supply a third RF signal from yet another RF generation unit to the lower electrode 111. In addition to this, in other alternative embodiments, a DC voltage may also be applied to the upper electrode showerhead assembly 12. Further, in various embodiments, the amplitude of one or more RF signals (i.e., the first RF signal, the second RF signal, etc.) may be pulsed or modulated. The amplitude modulation may include pulsing the RF signal amplitude between an on state and an off state, or between two or more different on states. The phase matching of the RF signal can be controlled, and the phase matching of the amplitude modulation of two or more RF signals can be synchronized or made asynchronous.

[0116] The exhaust system 40 may be connected, for example, to an exhaust port 10e provided at the bottom of the reaction chamber 10. The exhaust system 40 may include a vacuum pump such as a pressure valve, a turbomolecular pump, a roughing pump, or a combination thereof.

[0117] In the present embodiment, the control unit 50 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various processes described herein. The control unit 50 may be configured to control the respective elements of the plasma processing apparatus 1 to perform the various processes described herein. The control unit 50 may include, for example, a computer 51. The computer 51 includes, for example, a processing unit (CPU: Central Processing Unit) 511, a storage unit 512, and a communication interface 513. The processing unit 511 may be configured to perform various control operations based on a program stored in the storage unit 512. The storage unit 512 may include at least one memory type selected from the group consisting of an auxiliary storage device such as a RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), and an SSD (Solid State Drive). The communication interface 513 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0118] As described above, the apparatus of the embodiment is an etching apparatus and includes a reaction chamber that provides a processing space. The etching apparatus includes a stage disposed inside the reaction chamber, the stage having a plurality of zones capable of independently controlling temperature and a mounting surface capable of mounting a substrate. The etching apparatus includes a gas supply unit configured to supply a processing gas into the reaction chamber, and the etching apparatus includes a control unit configured to control the temperature of the plurality of zones and the operation of the gas supply unit. The control unit causes each unit to perform an etching method. The etching method includes step a): providing a substrate having an etched film onto the stage. The etching method includes step b): locally etching the etched film to form a recess. The etching method includes step c): setting the temperature of the stage to a first temperature and forming a first film having a first film thickness distribution on the sidewall of the recess. The etching method includes step d): further locally etching the etched film on which the first film is formed. The etching method includes step e): setting the temperature of the stage to a second temperature different from the first temperature and forming a second film having a second film thickness distribution different from the first film thickness distribution on the sidewall of the recess.

[0119] The above-described embodiments are merely exemplary and are not intended to limit the scope of the present disclosure. Therefore, various additions, omissions, substitutions, and changes can be made without departing from the gist of the present disclosure.

Claims

1. An etching method, comprising: Step a), providing a substrate having an etched film to a mounting table; Step b), locally etching the etched film by plasma generated from a first gas to form a recess; Step c), after performing the local etching, setting the temperature of the mounting table to a first temperature, and forming a first film having a first film thickness distribution on the sidewall of the recess by introducing a second gas different from the first gas; Step d), further locally etching the etched film having the first film formed thereon by plasma generated from a third gas different from the second gas; and Step e), after performing the local etching, setting the temperature of the mounting table to a second temperature different from the first temperature, and forming a second film having a second film thickness distribution different from the first film thickness distribution on the sidewall of the recess by introducing a fourth gas different from the third gas.

2. The etching method according to claim 1, wherein the second temperature is higher than the first temperature.

3. The etching method according to claim 1, wherein by adjusting a first section of the mounting table corresponding to a first region of the substrate and a second section of the mounting table corresponding to a second region of the substrate to different temperatures, at least one of the thickness and position of the first film formed in the first region is changed compared with at least one of the thickness and position of the first film formed in the second region.

4. The etching method according to claim 3, wherein the first region is a region including the center of the substrate, and the second region is a region including the edge of the substrate.

5. An etching method, comprising: Step a), providing a substrate having an etched film to a mounting table; Step b), locally etching the etched film to form a recess; Step c), setting the temperature of the mounting table to a first temperature, and forming a first film having a first film thickness distribution on the sidewall of the recess; Step d), further locally etching the etched film having the first film formed thereon; and Step e), setting the temperature of the mounting table to a second temperature different from the first temperature, and forming a second film having a second film thickness distribution different from the first film thickness distribution on the sidewall of the recess, wherein step c) includes: Step c-1), supplying a first reactant to adsorb the first reactant on the sidewall of the recess; and Step c-2), supplying a second reactant to react the first reactant with the second reactant to form a film, wherein step e) includes: Step e-1), supplying a third reactant to adsorb the third reactant on the sidewall of the recess; and Step e-2), supplying a fourth reactant to react the third reactant with the fourth reactant to form a film, by making the length of the processing time of step c-2) different from the length of the processing time of step e-2), further changing at least one of the thickness and position of the formed film.

6. The etching method according to any one of claims 1 to 5, wherein The first film thickness distribution is a distribution in which the film thickness changes in at least one of the thickness direction and the radial direction of the substrate.

7. The etching method according to any one of claims 1 to 5, wherein The second film thickness distribution is a distribution in which the film thickness changes in at least one of the thickness direction and the radial direction of the substrate.

8. The etching method according to any one of claims 1 to 5, wherein The film to be etched includes a silicon-containing layer.

9. The etching method according to any one of claims 1 to 5, wherein The substrate has a carbon-containing mask on the film to be etched.

10. The etching method according to any one of claims 1 to 5, wherein The steps b), c), d), and e) are repeated until the aspect ratio of the recess becomes at least 40.

11. An etching method, comprising: Step a), providing a substrate having a film to be etched on a stage; Step b), locally etching the film to be etched by plasma generated from a first gas to form a recess; Step c), after the local etching, setting at least two of a plurality of sections of the stage to different temperatures, and for the at least two sections, forming a film having different film thickness distributions in the depth direction on the sidewalls of the recess by introducing a second gas different from the first gas; and Step d), further locally etching the film to be etched on which the film is formed by plasma generated from a third gas different from the second gas.

12. An etching apparatus, comprising: A reaction chamber that provides a processing space; A stage provided inside the reaction chamber, having a plurality of sections capable of independently controlling temperature and having a mounting surface capable of mounting a substrate; A gas supply unit for supplying a processing gas into the reaction chamber; and A control unit that controls the temperature of the plurality of sections and the operation of the gas supply unit, The control unit causes each part to execute the following etching method, The etching method includes: Step a), providing a substrate having a film to be etched on a stage; Step b), locally etching the film to be etched by plasma generated from a first gas to form a recess; Step c), after the local etching, setting the temperature of the stage to a first temperature, and forming a first film having a first film thickness distribution on the sidewalls of the recess by introducing a second gas different from the first gas; Step d), further locally etching the film to be etched on which the first film is formed by plasma generated from a third gas different from the second gas; and Step e), after the local etching, setting the temperature of the stage to a second temperature different from the first temperature, and forming a second film having a second film thickness distribution different from the first film thickness distribution on the sidewalls of the recess by introducing a fourth gas different from the third gas.

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