Substrate processing method and substrate processing apparatus

Abstract

The method comprises the following steps: a first step of supplying a processing gas containing a halogen-containing gas and an alkaline gas to a substrate in which a recessed part having a side wall formed by a silicon film and a bottom wall formed by a germanium-containing film is formed, so as to modify the surface of the silicon film and generate a reaction product; a second step for increasing the width of the recess by removing the reaction product; a step in which a cycle comprising the first step and the second step is performed a plurality of times; and performing the first step of the preceding cycle under a first processing condition, and performing the first step of the following cycle under a second processing condition different from the first processing condition.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing method and a substrate processing device. Background Art

[0002] When manufacturing a semiconductor device, a Si film is sometimes selectively etched among Si films and SiGe films formed on the surface of a semiconductor wafer (hereinafter referred to as a wafer) serving as a substrate. For example, Patent Document 1 describes the following: F2 gas and NH3 gas are used as etching gases, and the above-mentioned selective etching is performed by setting the ratio of NH3 gas to the etching gas to a predetermined value.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6426489 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The present disclosure provides a technology capable of suppressing the roughness of the surface of a silicon film forming a recessed portion after etching and controlling the shape of the recessed portion.

[0008] Solutions for solving problems

[0009] The substrate processing method disclosed herein comprises the following steps:

[0010] In a first step, a processing gas containing a halogen-containing gas and an alkaline gas is supplied to a substrate having a concave portion formed with a side wall formed of a silicon film and a bottom wall formed of a germanium-containing film, so as to modify the surface of the silicon film to generate a reaction product;

[0011] A second step of removing the reaction product to enlarge the width of the recess;

[0012] A step of performing a cycle consisting of the first step and the second step a plurality of times; and

[0013] The first step of the cycle that is performed first is performed under a first processing condition, and the first step of the cycle that is performed later is performed under a second processing condition that is different from the first processing condition.

[0014] Effects of the Invention

[0015] The present disclosure can suppress the roughness of the surface of a silicon film forming a recessed portion after etching and control the shape of the recessed portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 11 is a longitudinal sectional side view of a wafer subjected to a process according to one embodiment of the present disclosure.

[0017] Figure 2 It is an explanatory diagram showing the change of the recessed portion before and after etching.

[0018] Figure 3 is a longitudinal sectional side view of the wafer after etching.

[0019] Figure 4 It is an explanatory diagram showing a state of change of the Si film forming the concave portion.

[0020] Figure 5 It is an explanatory diagram showing a state of change of the Si film forming the concave portion.

[0021] Figure 6 It is an explanatory diagram showing a state of change of the Si film forming the concave portion.

[0022] Figure 7 It is an explanatory diagram showing how the concave portion changes during etching.

[0023] Figure 8 It is an explanatory diagram showing a case where the recessed portion has a rectangular shape.

[0024] Fig. 9 It is an explanatory diagram showing a state where the concave portion has a circular shape.

[0025] Fig.10 This is a flowchart showing the processing of this embodiment.

[0026] Fig.11 It is a top view showing one embodiment of a substrate processing apparatus for performing the above-mentioned processing.

[0027] Fig.12 It is a longitudinal sectional side view showing an example of a process module provided in the substrate processing apparatus.

[0028] Fig.13 It is a graph showing the results of the evaluation test.

[0029] Fig.14 It is a graph showing the results of the evaluation test.

[0030] Fig.15 It is a graph showing the results of the evaluation test. DETAILED DESCRIPTION

[0031] One embodiment of the substrate processing method disclosed herein will be described. Figure 11 is a longitudinal sectional side view of the surface of a wafer W as a substrate, showing a state before the etching process involved in this embodiment is performed. A lower film 11 is formed on the wafer W. Moreover, SiGe (silicon germanium) films 12 and Si (silicon) films 13 are repeatedly and alternately stacked on the lower film 11. By forming a repeated structure like this, SiGe films 12 and Si films 13 are respectively formed in multiple layers in the thickness direction of the wafer W. The thickness direction of the wafer W is set as the longitudinal direction for description. The Si film 13 is formed by epitaxial growth, for example.

[0032] A mask film 14 is stacked on the uppermost Si film 13 of the above-mentioned repeated structure to prevent etching from above the Si film 13. Furthermore, a recess extending in the longitudinal direction is formed from the mask 14 to the upper side of the lower film 11. The recess is formed along Figure 1 A groove 15 extending in the front and back directions of the paper surface. The groove 15 has an opening on the upper surface of the mask film 14. The side walls of the groove 15 are composed of the surface portions of the mask film 14, the Si film 13 and the lower film 11, and each SiGe film 12 is located away from the side walls of the groove 15. Therefore, when observing the longitudinal section, recesses toward the left side are formed in multiple layers at intervals on the left wall of the groove 15, and recesses toward the right side are formed in multiple layers at intervals on the right wall of the groove 15. These recesses facing the left and right sides, respectively, are defined as recesses 16. Therefore, recesses 16 are formed in multiple layers in the thickness direction of the wafer W, and each recess 16 is formed in a manner having an opening in a direction intersecting the thickness direction.

[0033] The groove 15 and the concave portion 16 are formed so as to constitute a bilaterally symmetrical structure, and the longitudinal width of each concave portion 16 is the same or substantially the same. Hereinafter, the concave portion 16 on the upper side, the concave portion 16 on the lower side, and the concave portion 16 between the upper side and the lower side in the Si film 13 are sometimes described as the top concave portion 16, the bottom concave portion 16, and the middle concave portion 16, respectively. In addition, the height of the stacked body composed of the SiGe film 12 and the Si film 13 (=the height from the upper surface of the lower film 11 to the lower end of the mask film 14) is, for example, 4 μm.

[0034] Figure 2 A recess 16 is shown in an enlarged manner. The upper side is the same as the above Figure 1The corresponding state before etching, the lower side is the state after etching described later. Since it is the film structure already described, the side wall of the recess 16 is composed of the Si film 13, and the bottom wall (inner wall) is composed of the SiGe film 12. Later, for the convenience of explanation, the walls forming each recess 16 in this way are sometimes recorded as the upper wall 21, the lower wall 22, and the transverse wall 23. The upper wall 21 and the lower wall 22 are composed of the Si film 13, and the upper wall 21 of any recess 16 is the lower wall 22 of the upper recess 16 of the recess 16. The transverse wall 23 is composed of the SiGe film 12 before etching. With respect to the recess 16 before etching, the upper wall 21 and the lower wall 22 are perpendicular or substantially perpendicular to the transverse wall 23, and when observing the longitudinal section, each wall of the upper wall 21 and the lower wall 22 forms a corner with the transverse wall 23, and the angle is 90° or substantially 90°.

[0035] When the gas is supplied to the wafer W, the gas is introduced into the groove 15 and then supplied into the recesses 16 of each layer. In this embodiment, by introducing the processing gas from the surface of the wafer W into each recess 16, the lower surface side of the upper wall 21 and the upper surface side of the lower wall 22 are etched. That is, the thickness of the Si film 13 forming the side wall of the recess 16 is reduced to widen the recess 16 in the longitudinal direction. Through this widening, the lateral wall 23 of the recess 16 after etching is composed of the SiGe film 12 and the Si film 13. In addition, Figure 2 This is a schematic diagram showing a desired state in which the shape of the recessed portion 16 after etching is a rectangular shape described later and the roughness of the lower surface of the upper wall 21 and the upper surface of the lower wall 22 is suppressed.

[0036] Specifically describing the above-mentioned etching process, F2 (fluorine) gas as a halogen-containing gas and NH3 gas as an alkaline gas are supplied to the wafer W as processing gases to modify the surface of the Si film 13 constituting the upper wall 21 and the lower wall 22 to generate reaction products. The process of modifying the Si film 13 by the processing gas in this way is set as a processing gas supply process. Next, a heating process is performed by heating the wafer W to sublimate the reaction product so as to widen the recess 16. The sublimated reaction product is various products such as AFS described later. By repeating a cycle consisting of a processing gas supply process as a first process and a heating process as a second process, the longitudinal width of the recess 16 is set to a desired size. In addition, the processing gas supply process and the heating process are respectively performed in a state where the wafer W is accommodated in a processing container in which a vacuum atmosphere at a specified pressure is formed.

[0037] The above-mentioned processing gas mainly acts on the Si film 13 of the Si film 13 and the SiGe film 12. Therefore, the Si film 13 is selectively etched relative to the SiGe film 12. The above-mentioned reaction product is ammonia fluorosilicate [AFS: (NH4) SiF6]. In addition, in the following description, the supply time of the processing gas refers to the supply time of the processing gas in the above-mentioned one cycle, which is the time when both the F2 gas as the halogen-containing gas and the NH3 gas as the alkaline gas are supplied to the wafer W, unless otherwise stated.

[0038] It is expected that the concave portion 16 after etching satisfies the first to third requirements described below. The first requirement is that the roughness (surface roughness) of the lower surface of the upper wall 21 and the upper surface of the lower wall 22 of the Si film 13 is relatively small. The second requirement is described. After etching, as before etching, the bottom side of the concave portion 16, the walls of the upper wall 21 and the lower wall 22 form an angle of 90° or approximately 90° with the transverse wall 23. By forming such an angle, the uniformity of the longitudinal width between the opening side and the bottom side of the concave portion 16 is high. Below, for the sake of convenience, the shape of the concave portion 16 with such an angle and high uniformity of longitudinal width is described as a rectangular shape. On the other hand, the shape of the concave portion that does not form such an angle, the concave portion 16 is a horizontally inverted U-shape when observing the longitudinal section, and the longitudinal width of the bottom side is smaller than the longitudinal width of the opening side is set to a circular shape. The second requirement is to make the shape of the concave portion 16 close to a rectangular shape (improve the rectangularity).

[0039] The third requirement is to suppress the variation in the vertical width of the recessed portion 16 at each height position, that is, to suppress the variation in the etching amount between the recessed portions 16 at the top, middle, and bottom. Figure 3 It is shown Figure 1 The schematic diagram of the state of the wafer W after being etched in a manner that satisfies the first to third requirements above, the aforementioned Figure 2 The etched recess 16 shows Figure 3 One of the recesses 16 of the wafer W is shown.

[0040] The roughness of the Si film 13 required for the first step is described in detail. The Si film 13 reacts with the F2 gas and the NH3 gas as the processing gas as shown in the following formula 1 to generate a product (SiF4). The SiF4 reacts as shown in formula 2 to generate AFS. The roughness of the Si film 13 after etching varies depending on the processing conditions, but it can be considered to be related to the amount of AFS generated in the processing gas supply process.

[0041] Si+F2+NH3→SiF4+NH3…Formula 1

[0042] SiF4+H2+F2+2NH3→(NH4)SiF6…Formula 2

[0043] Below, by referring to Figures 4 to 6 This is to explain the difference in roughness that is believed to be caused by the difference in the amount of AFS generated. Figures 4 to 6 , the change of the upper surface of the lower wall 22 of the recessed portion between the time when the processing gas is supplied and the time when the etching is completed is schematically shown, but the lower surface of the upper wall 21 also changes in the same way as the upper surface of the lower wall 22. The amount of AFS generated in the processing gas supply step is Figure 4 , Figure 5 , Figure 6 The order becomes more.

[0044] exist Figure 4 : The following state is shown in FIG. 1 : Since the amount of AFS generated is relatively small, the AFS layer 31 is dispersedly formed on the upper surface of the lower wall 22 during the process gas supply process. On this upper surface, the contact between the portion covered by the AFS layer 31 and the process gas is suppressed, so it is not easy to be modified by the reaction with the process gas. That is, on the upper surface of the lower wall 22, the portion where the AFS layer 31 is formed and the portion where the AFS layer 31 is not formed have different reactivity to the process gas. Due to the difference in reactivity, after etching, the surface of the lower wall 22 is formed with unevenness. As described above, since the AFS layer 31 is dispersedly formed, the surface roughness of the upper surface of the lower wall 22 is small. That is, the width of the concave portion and the width of the convex portion in the above-mentioned unevenness are relatively small.

[0045] exist Figure 5 In the process gas supply step, the AFS layer 31 is formed as a thin layer covering the entire upper surface of the lower wall 22, thereby suppressing the reaction with the process gas at each location on the upper surface to the same extent. As a result, the entire upper surface of the lower wall 22 is etched with high uniformity, so that the etched surface becomes flat or substantially flat.

[0046] Figure 6 : A large amount of AFS is generated in the process gas supply step, so that the AFS layer 31 covers the entire upper surface of the lower wall 22, and the thickness of the AFS layer 31 varies at various locations on the upper surface. That is, the surface roughness of the AFS layer 31 is large. The thicker the AFS layer 31 is, the more difficult it is for the process gas to contact the lower wall 22, and thus the surface roughness of the lower wall 22 after etching is also greater. That is, in terms of concavity and convexity, the width of the concave portion and the width of the convex portion are relatively large.

[0047] Will be like Figure 4 The state where the surface roughness is relatively small as shown in the figure is defined as micro roughness. Figure 6The state where the surface roughness is relatively large as shown is set as large roughness. As described above, when the amount of AFS generated shifts from the appropriate range to the smaller side, the roughness of the surface of the Si film 13 with fine roughness becomes larger, and when the amount of AFS generated shifts from the appropriate range to the larger side, the roughness of the surface of the Si film 13 with large roughness becomes larger. Moreover, according to the above-mentioned formulas 1 and 2, the amount of AFS generated is affected by the flow ratio of the F2 gas and the NH3 gas supplied to the wafer W as the processing gas. When the flow rate of NH3 gas is relatively large relative to the flow rate of F2 gas, the amount of AFS generated increases. In addition, the longer the supply time of the processing gas, the more AFS is generated. In addition, with respect to the flow rate of NH3 gas in the processing gas relative to the flow rate of F2 gas (the flow rate of NH3 gas / the flow rate of F2 gas), it is sometimes recorded as the flow rate ratio of NH3 gas below. Therefore, a large flow rate ratio of NH3 gas means that the flow rate of NH3 gas is large relative to the flow rate of F2 gas (=the ratio of NH3 gas to F2 gas in the processing gas is large).

[0048] Next, the shape of the concave portion 16 after etching, which is the second requirement, will be described. Depending on the processing conditions, the shape of the concave portion 16 after etching changes between a rectangular shape and a circular shape. The following describes the process that is estimated to occur before these rectangular shapes and circular shapes are formed. First, refer to Figure 7-8 The process of forming the rectangular shape is described below. F2 gas 41 and NH3 gas 42 as processing gases enter the recess 16 ( Figure 7 The SiF4 reacts with the lower surface of the upper wall 21 and the upper surface of the lower wall 22 of the Si film 13 as shown in the above-mentioned formula 1 to generate SiF4. A part of the SiF4 is released into the recess 16 as a gas, while another part reacts as shown in the above-mentioned formula 2 to form the AFS layer 31.

[0049] The F2 gas 41 and the NH3 gas 42 act on the upper wall 21 and the lower wall 22 as well as the transverse wall 23, and the surface layer of the SiGe film 12 constituting the transverse wall 23 is modified and slightly etched, thereby releasing the GeF4 (germanium tetrafluoride) gas 43. By etching the transverse wall 23 in this way, a part of the Si film 13 is newly exposed inside the concave portion 16 at the bottom side of the concave portion 16, thereby forming the upper wall 21 and the lower wall 22 ( Figure 7 This part is set as the newly exposed part 44.

[0050] The newly exposed portion 44 is exposed to the recess 16 in the middle of supplying the processing gas, and therefore is exposed to the F2 gas 41 and the NH3 gas 42 for a short time compared to the portion of the Si film 13 where the upper wall 21 and the lower wall 22 are formed before etching. Therefore, the amount of reaction with these F2 gas 41 and NH3 gas 42 is relatively small. In addition, the closer to the bottom side of the recess 16, the more difficult it is for the F2 gas 41 and the NH3 gas 42 to enter. According to the above situation, with respect to the upper wall 21 and the lower wall 22 including the newly exposed portion 44, the closer to the bottom side of the recess 16, the smaller the amount of reaction with the F2 gas 41 and the NH3 gas 42. However, the GeF4 gas 43 is reactive with respect to the Si film 13, and reacts to a greater extent with the Si film 13 on the bottom side of the recess 16 by being generated from the SiGe film 12. Therefore, from the opening of the recess 16 to the bottom side, the Si film 13 reacts with high uniformity ( Figure 8 Therefore, after the reaction products generated in the process gas supply process are removed by the heating process, the recess 16 becomes a rectangular shape ( Figure 8 In addition, the reaction product generated in the SiGe film 12, that is, the AFG layer, is shown as 45, and the reaction product of the GeF4 gas 43 and the Si film 13 is shown as 46. The AFG layer 45 and the reaction product 46 are also removed together with the AFS layer 45. The AFG layer 45 will be described later.

[0051] Next, the estimation of the process of forming a circular shape is described. Figure 7 As the reaction between the surface layer of the SiGe film 12 and the processing gas progresses from the state shown in the lower part of the figure, the surface layer gradually changes into the AFG〔(NH4)GeF6〕layer 45. As the change into the AFG layer 45 progresses, the release amount of the GeF4 gas 44 decreases. Therefore, as far as the upper wall 21 and the lower wall 22 are concerned, the reaction amount with respect to the GeF4 gas 44 and / or the F2 gas 41 and the NH3 gas 42 decreases as they move toward the bottom side of the recess 16 ( Fig. 9 Therefore, after the reaction product is removed by the heating process, the concave portion 16 becomes a circular shape ( Fig. 9 As can be seen from the above, the longer the supply time of the processing gas is, or the larger the flow rate ratio of the NH3 gas is, the easier it is for the formation of the AFG layer 45 to progress (= the release of the GeF4 gas 44 is easier to reduce), and thus the easier it is for the AFG layer 45 to become a circular shape.

[0052] Next, the deviation of the etching amount between the top, middle, and bottom related to the third requirement is described. Since it is more difficult for the processing gas to enter the bottom side of the groove 15, when the supply time of the processing gas is relatively short, the ease of contact and reaction between the upper wall 21 and the lower wall 22 of the recess 16 and the processing gas conforms to the order of top>middle>bottom. Therefore, the size of the etching amount changes in this order.

[0053] However, as shown in the evaluation test described later, it can be confirmed that there is a tendency that as the supply time of the processing gas becomes longer, the etching amount increases closer to the bottom side (that is, with respect to the etching amount, top < middle < bottom). It can be considered that one of the reasons is that since the supply time of the processing gas is long, the AFS layer 31 formed closer to the top side (the opening side of the groove 15) is thicker, and the reaction between the upper wall 21 and the lower wall 22 and the processing gas is more hindered. In addition, the greater the flow rate of the NH3 gas, the easier it is to increase the thickness of the AFS layer 31 on the top side, so there is a tendency that the etching amount increases closer to the bottom side.

[0054] As described above, by setting the processing conditions such that the flow rate of NH3 gas is relatively small and / or the supply time of the processing gas is short, the recess 16 after etching has a tendency to form a small roughness, a tendency to become a rectangular shape, and a tendency to increase the etching amount on the top side. On the contrary, by setting the processing conditions such that the flow rate of NH3 gas is relatively large and / or the supply time of the processing gas is long, the recess 16 after etching has a tendency to form a large roughness, a tendency to become a circular shape, and a tendency to increase the etching amount on the bottom side. Regarding the flow rate ratio of NH3 gas and the supply time of the processing gas, the appropriate range for making the roughness converge within the allowable range, the appropriate range for forming a rectangular shape, and the appropriate range for making the etching amount consistent between the top and the bottom are not necessarily consistent. Therefore, when repeating a cycle consisting of a processing gas supply process and a heating process, when the processing gas supply process of each cycle is set to the same processing conditions, it is difficult to fully meet all the requirements of the first to third requirements mentioned above.

[0055] Therefore, in this embodiment, the processing conditions in the processing gas supply step performed in the first cycle and the processing gas supply step performed in the second cycle are different. Fig.10 The processing flow in this embodiment is shown in FIG. The cycle is set to be performed Z times in total, and the heating process is performed after the processing gas supply process under the first processing condition is performed. A front-end cycle (step S1) is repeated X times. Thereafter, the heating process is performed after the processing gas supply process under the second processing condition is performed. A back-end cycle (step S2) is repeated Y times (Z times - X times).

[0056] By changing the processing conditions as described above, it is possible to prevent the roughness, the shape of the recess, and the etching amount between the top, middle, and bottom from showing a strong specific tendency compared to the case where the processing is performed under a single processing condition, and the first to third requirements can be met. However, regarding the shape and roughness of the recess 16 after etching, it is confirmed that the processing conditions performed in the front cycle have a greater impact than those in the back cycle, which will be shown as an evaluation test later. In other words, when the processing gas supply process of the front cycle is set to a condition that forms a rectangular shape and a small roughness, the recess 16 after etching has a tendency to become a state formed with a rectangular shape and a small roughness. On the contrary, when the processing gas supply process of the front cycle is set to a condition that forms a circular shape and a large roughness, the recess 16 after etching has a tendency to become a state formed with a circular shape and a large roughness.

[0057] As long as the roughness is within the allowable range, it can be slightly formed. Therefore, in order to form a rectangular shape, as the first processing condition in the front cycle, it can be set to a processing condition that tends to form a rectangular shape and a small roughness, and as the second processing condition in the back cycle, it can be set to a processing condition that tends to form a circular shape and a large roughness compared to the first processing condition. Therefore, specifically, the flow ratio of NH3 gas in the first processing condition is made smaller than the flow ratio of NH3 gas in the second processing condition, or the supply time of the processing gas in the first processing condition is made shorter than the supply time of the processing gas in the second processing condition. In addition, in order to increase the tendency to form a rectangular shape, it is preferred to set the first processing condition of the front cycle and the second processing condition of the back cycle in this way, for example, to set the number of times the front cycle is performed (X times) ≥ the number of times the back cycle is performed (Y times).

[0058] In addition, sometimes it is more necessary to meet the first requirement (requirement to suppress roughness) than the second requirement (requirement to improve rectangularity). In this case, as described above, in the recess 16 after etching, the first processing condition in the front cycle has a greater impact, so as the first processing condition, a condition that can suppress roughness is selected. Moreover, as the second processing condition in the back cycle, a condition that can correct the etching amount between the top-middle-bottom and correct the shape of the recess 16 in a way that improves rectangularity can be selected. Specifically, the flow ratio of NH3 gas in the first processing condition is greater than the flow ratio of NH3 gas in the second processing condition, or the supply time of the processing gas in the first processing condition is longer than the supply time of the processing gas in the second processing condition. In the case where you want to obtain a higher suppressive effect on roughness like this, in order to increase the effect, it is preferably set to the number of times the front cycle is performed (X times) ≥ the number of times the back cycle is performed (Y times).

[0059] In addition, in this embodiment, in order to improve the rectangularity, the following settings are made: the flow ratio of the NH3 gas in the first processing condition is set to be greater than the flow ratio of the NH3 gas in the second processing condition, and the supply time of the processing gas in the first processing condition is shorter than the supply time of the processing gas in the second processing condition, and it is set that the number of times the front-end cycle is performed (X times)>the number of times the back-end cycle is performed.

[0060] An example of a specific processing condition is further described. In view of the results of subsequent evaluation tests, for example, the flow ratio of NH3 gas (flow rate of NH3 gas / flow rate of F2 gas) is set to a range of 0.01 to 0.014 in the first processing condition and the second processing condition, respectively. Therefore, the flow ratio of NH3 gas in at least one of the first processing condition and the second processing condition is less than 0.014. In addition, the supply time of the processing gas is set to a range of, for example, 10 seconds to 15 seconds in the first processing condition and the second processing condition, respectively. In addition, in this specification, the supply time of the processing gas refers to the time when the halogen-containing gas (F2 gas in the present embodiment) and the alkaline gas (NH3 gas in the present embodiment) constituting the processing gas are simultaneously supplied to the wafer W (that is, the time when they are supplied to the processing container storing the wafer W).

[0061] Reference Fig.11 The substrate processing device 5 is explained in a top view. Fig.10 The substrate processing apparatus 5 includes a loading and unloading section 51 for loading and unloading wafers W, two load lock chambers 61 disposed adjacent to the loading and unloading section 51, two heat treatment modules 60 disposed adjacent to the two load lock chambers 61, and two processing modules 7 disposed adjacent to the two heat treatment modules 60. The processing module 7 corresponds to the first processing section, and the heat treatment module 60 corresponds to the second processing section.

[0062] The loading and unloading section 51 includes a normal pressure transfer chamber 53 and a carrier mounting table 55. The normal pressure transfer chamber 53 is set to a normal pressure atmosphere and is used to set the first substrate transfer mechanism 52. The carrier mounting table 55 is set at the side of the normal pressure transfer chamber 53 and is used to place the carrier 54 for storing the wafer W. 56 in the figure is an aligner adjacent to the normal pressure transfer chamber 53. The aligner is set to rotate the wafer W to optically obtain the eccentricity so as to align the position of the wafer W relative to the first substrate transfer mechanism 52. The first substrate transfer mechanism 52 transfers the wafer W between the carrier 54 on the carrier mounting table 55, the aligner 56, and the load interlock vacuum chamber 61.

[0063] A second substrate transfer mechanism 62 having, for example, a multi-joint arm structure is provided in each load lock chamber 61, and the second substrate transfer mechanism 62 transfers the wafer W between the load lock chamber 61, the heat treatment module 60, and the process module 7. The processing container constituting the heat treatment module 60 and the processing container constituting the process module 7 are set to a vacuum atmosphere, and the load lock chamber 61 is switched between a normal pressure atmosphere and a vacuum atmosphere so that the wafer W can be transferred between the processing containers in these vacuum atmospheres and the normal pressure transfer chamber 53.

[0064] Reference numeral 63 in the figure denotes a gate valve that can be opened and closed freely, and is respectively disposed between the atmospheric transfer chamber 53 and the load lock chamber 61, between the load lock chamber 61 and the heat treatment module 60, and between the heat treatment module 60 and the treatment module 7. The heat treatment module 60 includes the above-mentioned treatment container, an exhaust mechanism for exhausting the treatment container to form a vacuum atmosphere, and a stage disposed in the treatment container and capable of heating the wafer W placed therein, and the heat treatment module 60 is configured to be able to perform the above-mentioned heating process.

[0065] Reference Fig.12 The processing module 7 is explained with reference to the longitudinal sectional side view. The processing module 7 performs the processing gas supply process described above. 71 in the figure is a processing container constituting the processing module 7. 72 in the figure is a transfer port for the wafer W opened in the side wall of the processing container 71, which is opened and closed by the above-mentioned gate valve 63. A stage 81 for mounting the wafer W is provided in the processing container 71, and a lifting pin not shown in the figure is provided on the stage 81. The wafer W is transferred between the above-mentioned second substrate conveying mechanism 62 and the stage 81 with the help of the lifting pin.

[0066] A temperature adjustment unit 82 is embedded in the stage 81 to set the temperature of the wafer W placed on the stage 81 to a temperature described later. The temperature adjustment unit 82 is configured as a flow path that constitutes a part of a circulation path for a fluid for temperature adjustment, such as water, to flow, and adjusts the temperature of the wafer W by exchanging heat with the fluid. However, the temperature adjustment unit 82 is not limited to such a flow path of the fluid, and may be configured, for example, by a heater for resistance heating.

[0067] In addition, one end of the exhaust pipe 83 opens in the processing container 71, and the other end of the exhaust pipe 83 is connected to an exhaust mechanism 85, such as a vacuum pump, via a valve 84 as a pressure changing mechanism. By adjusting the opening of the valve 84, the pressure in the processing container 71 is adjusted to a pressure within a range described below to perform processing.

[0068] A gas shower head 86 as a processing gas supply mechanism is provided on the upper side of the processing container 71 so as to face the stage 81. The gas shower head 86 is connected to the downstream side of the gas supply paths 91 to 94, and the upstream sides of the gas supply paths 91 to 94 are connected to the gas supply sources 96 to 99 via the flow adjustment section 95, respectively. Each flow adjustment section 95 includes a valve and a mass flow controller. The gas supplied from the gas supply sources 96 to 99 to the downstream side is supplied and cut off by opening and closing the valve included in the flow adjustment section 95.

[0069] F2 gas, NH3 gas, Ar (argon) gas, and N2 (nitrogen) gas are respectively supplied from gas supply sources 96, 97, 98, and 99. Therefore, HF gas, NH3 gas, Ar gas, and N2 gas can be respectively supplied from the gas shower head 86 into the processing container 71. Ar gas and N2 gas are supplied into the processing container 71 together with F2 gas and NH3 gas as carrier gas.

[0070] In addition, if Fig.11 As shown, the substrate processing device 5 includes a control unit 50 as a computer, and the control unit 50 includes a program, a memory, and a CPU. The program includes commands (various steps) for performing the processing of the wafer W and the conveyance of the wafer W as described above, and the program is stored in a storage medium such as an optical disk, a hard disk, a magneto-optical disk, a DVD, etc. and installed in the control unit 50. The control unit 50 outputs a control signal to each part of the substrate processing device 5 through the program to control the operation of each part. Specifically, the operation of the processing module 7, the operation of the heat treatment module 60, the operation of the first substrate conveying mechanism 52, the operation of the second substrate conveying mechanism 62, and the operation of the aligner 56 are controlled by the control signal. As the operation of the above-mentioned processing module 7, for example, each operation includes the temperature of the fluid supplied to the stage 81, the supply and cutoff of each gas from the gas shower head 86, and the adjustment of the exhaust flow rate by the valve 84.

[0071] The transport path of the wafer W in the substrate processing apparatus 5 will be described. Figure 1The carrier 54 of the wafer W on which each film is formed as described is placed on the carrier mounting table 55. Then, the wafer W is transported in the order of the atmospheric pressure transfer chamber 53 → the aligner 56 → the atmospheric pressure transfer chamber 53 → the load lock vacuum chamber 61, and is transported to the processing module 7 via the heat treatment module 60. Then, the process gas supply process is performed as described above to modify the surface layer of the upper wall 21 and the lower wall 22 forming the recess 16 to form the AFS layer 31. Next, the wafer W is transported to the heat treatment module 60 to perform sublimation of the AFS layer 31 and other reaction products. Thereafter, the wafer W is transported in a reciprocating manner between the processing module 7 and the heat treatment module 60, thereby repeating a cycle consisting of the process gas supply process and the heating process.

[0072] In the first to Xth cycles of the above cycle, if Fig.10 As described above, the process gas supply process is performed under the first process condition. In addition, in the cycle starting from the X+1th time, the process gas supply process is performed under the second process condition in which the flow rate ratio of the NH3 gas is larger and the supply time of the process gas is longer. The cycle under the second process condition is repeated Y times, and a total of Z (X+Y) cycles are completed. Figure 3 When each recess 16 has a desired longitudinal width as shown, the wafer W is transferred from the heat treatment module 60 in the order of the load lock chamber 61 to the atmospheric pressure transfer chamber 53 , and is returned to the carrier 54 .

[0073] The processing gas supply process in the above-mentioned cycle is supplemented. In the processing gas process, the processing container 71 of the processing module 7 is exhausted to, for example, 100mTorr (13.3Pa) to 10Torr (1333Pa), and the temperature of the wafer W is adjusted to, for example, -20°C to 60°C. In this state, F2 gas is supplied to the processing container 71 and NH3 gas is supplied to the processing container 71 in parallel (step T1). In addition, the time for supplying F2 gas and NH3 gas and the flow ratio of F2 gas and NH3 gas in step T1 are the processing gas supply time and NH3 gas flow ratio described so far. Moreover, after the supply of F2 gas and NH3 gas is stopped, N2 gas is supplied to the processing container 71 while exhausting the processing container 71, thereby purging the F2 gas and NH3 gas remaining in the processing container 71 (step T2). After the purge, the wafer W is moved out of the processing container 71. In addition, the heating step in the above cycle is also supplemented. In this heating step, the wafer W is heated to a temperature higher than the temperature of the wafer W in steps T1 and T2, for example, 80° C. to 300° C., so that the above reaction product is sublimated.

[0074] According to the present embodiment described above, by setting the processing conditions in the processing gas supply process in the front-stage cycle and the back-stage cycle to be different from each other, the first to third requirements can be met. That is, the roughness of the Si film 13 forming the upper wall 21 and the lower wall 22 of the concave portion 16 after etching can be suppressed, the concave portion 16 can be made into a rectangular shape, and the deviation of the longitudinal width of the concave portion 16 between the top-middle-bottom can be suppressed. Therefore, the yield of semiconductor products manufactured from the wafer W after etching can be improved.

[0075] The number of times the front-end cycle is performed, i.e., X times, and the number of times the back-end cycle is performed, i.e., Y times, are described as multiple times, but these X times and / or Y times may also be one time. Therefore, the front-end cycle and the back-end cycle may not be repeated. In addition, in the examples described so far, the flow ratio of the NH3 gas in the process gas supply process or the supply time of the process gas is changed only once, so as to set the process to the front-end cycle and the back-end cycle that follows it as two stages. It is not limited to the process set to two stages like this, and the change of the process conditions may be performed more than twice to set it to more than three stages.

[0076] In addition, the following is described: When performing a two-stage process, it is preferred that the flow ratio of the NH3 gas in the first cycle is greater than the flow ratio of the NH3 gas in the second cycle, or the supply time of the processing gas in the first cycle is shorter than the supply time of the processing gas in the second cycle to form a rectangular shape. In addition, the following is described: Regarding the number of cycles, it is preferred to set the number of first-stage cycles ≥ the number of second-stage cycles. In the case of performing a process in more than three stages, for example, it is set so that the processing conditions of the first stage and the processing conditions of any stage from the second stage onwards are in such a relationship. In addition, regarding the number of cycles, for example, it is sufficient to set the number of cycles in the first stage ≥ the number of cycles in any stage.

[0077] In addition, in the present embodiment, the atmosphere around the wafer W is maintained as a vacuum atmosphere from the start of the first cycle to the end of the last cycle, but for example, the cycles of each stage may be performed in different devices, and the wafer W may be moved between the devices by passing through the atmospheric atmosphere. However, from the viewpoint of preventing a decrease in productivity, it is preferred that the wafer W be processed in a vacuum atmosphere from the first cycle to the last cycle, as in the case of using the above-mentioned substrate processing device 5.

[0078] In addition, in any cycle, after the process gas supply step and before the heating step, the second fluorine-containing gas is supplied, thereby further suppressing the roughness of the Si film 13 after the etching is completed. The second fluorine-containing gas (i.e., halogen-containing gas) is, for example, HF (hydrogen fluoride) gas, and is therefore a gas of a different type from the first fluorine-containing gas, i.e., F2 gas, which constitutes the process gas. The HF gas is supplied to the wafer W in the process module 7.

[0079] The processing process in the processing module 7 when the HF gas is supplied is described. After the above steps are performed in the order of supply of the processing gas (step T1) and purging in the processing container 71 (step T2), HF gas is supplied into the processing container 71 (step T3). Then, after the supply of the HF gas is stopped, as step T4, the N2 gas in the processing container 71 is supplied and exhausted in the same manner as step T2 to purge the residual HF gas. Then, the wafer W is unloaded from the processing module 7. In addition, when the HF gas is supplied as the roughness suppression gas in this way, steps T1 to T4 are the first process, step T1 of supplying both the halogen-containing gas (F2 gas) and the alkaline gas (NH3 gas) corresponds to the first supply process, and step T3 of supplying only one of these gases corresponds to the second supply process.

[0080] It is considered that by supplying the HF gas, NH 3 contained in the AFS layer 31 formed in step T1 reacts with the HF gas to generate a reaction product, and the reaction product slightly etches the surface layer of the Si film 13 covered with the AFS layer 31, thereby suppressing the roughness.

[0081] The processing module 7 for performing the above-mentioned steps T1 to T4 is configured as follows: for example, in addition to the gas supply sources 96 to 99 described above, a supply source for HF gas is further provided, and the HF gas supply source is connected to the gas shower head 86 via a flow path. Moreover, in the flow path of the HF gas, a flow rate adjustment unit 95 is provided, similarly to the flow paths of other gases, to supply the HF gas at a desired flow rate into the processing container 71 via the gas shower head 86. In addition, when supplying the HF gas into the processing container 71, for example, Ar gas and N2 gas are also supplied into the processing container 71 as carrier gases.

[0082] In addition, as a gas for suppressing roughness, NH3 gas may be supplied to the wafer W instead of supplying HF gas to the wafer W. When NH3 gas is supplied in this way, it is considered that the NH3 gas reacts with the fluorine component contained in the AFS layer 31 formed in step T1 to generate a reaction product, and the reaction product slightly etches the surface layer of the Si film 13 covered by the AFS layer 31, thereby suppressing the roughness.

[0083] Furthermore, when NH3 gas is used as the roughness suppression gas, for example, F2 gas and NH3 gas as the processing gas may be supplied together, and NH3 gas may continue to be supplied to the wafer W after the supply of F2 gas is stopped, thereby omitting the purge with N2 gas in step T2. In addition, the supply of each gas for roughness suppression described above may be performed in any cycle. For example, it may be performed in the last cycle of each stage of the cycle, or it may be performed in each cycle.

[0084] It has been described that the temperature of the wafer W is made higher than the temperature during the process gas supply step when the reaction product is removed, but the removal is not limited to this. For example, it can also be performed in the following manner: after the above steps T1 and T2 are performed in the process module 7, the opening of the valve 74 provided in the exhaust pipe 73 is increased to reduce the pressure in the process container 71, thereby reducing the sublimation temperature of the reaction product. Therefore, it is not limited to performing one cycle in different process containers.

[0085] As for F2 gas and NH3 gas used as processing gas, the timing of supply end and the timing of supply start can be staggered as described above. In addition, the fluorine-containing gas contained in the processing gas is not limited to F2 gas, and for example, IF7 gas, IF5 gas, ClF3 gas, and SF6 gas can also be used. In addition, containing fluorine does not mean containing fluorine in the form of impurities, but means containing fluorine in the form of constituent components. The containing Ge described later also means containing Ge in the form of constituent components rather than in the form of impurities.

[0086] In addition, the recess 16 is not limited to the case where it is horizontal, and the present technology can also be applied when the recess 16 is opened in the vertical direction and the Si film constituting the side wall of such a recess 16 is etched. In this case, the recess 16 can be etched in a manner that meets the first requirement and the second requirement (roughness and rectangular shape requirements) among the first to third requirements described above.

[0087] It can be considered that even in the structure where the Ge film replaces the SiGe film 12 to form the lateral wall 23 of the recess 16, it is possible to use a fluorine-containing gas to generate GeF4 to etch the bottom side of the recess 16. Therefore, the lateral wall 23 of the recess 16 is not limited to being composed of the SiGe film 12, as long as it is composed of a film containing a Ge film.

[0088] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The embodiments described above may be omitted, replaced, modified, and combined in various ways without departing from the appended claims and the gist thereof.

[0089] 〔Evaluation Test〕

[0090] Next, evaluation tests 1 to 5 conducted on the present technology are described. Figure 1 The film structure substrate described in the embodiment is subjected to a cycle consisting of a process gas supply process and a heating process using the apparatus described in the embodiment, and the dimensions of each part are measured based on SEM images obtained before and after the process. Fig.10 The processing conditions were not changed between the front-end cycle and the back-end cycle described in the above, and the processing was performed under a single processing condition. In addition, in the evaluation tests 1 to 5, the period of supplying the F2 gas and the period of supplying the NH3 gas in the processing gas supply process were the same. In other words, the timing of starting to supply these gases to the processing container 71 was the same, and the timing of ending the supply of these gases to the processing container 71 was also the same.

[0091] The dimensions measured in each evaluation test are the following three dimensions. One dimension is the lateral width of the groove 15, which is hereinafter referred to as the groove width dimension. Another dimension is the longitudinal width of the recess 16 at a position that is a certain distance away from the opening of the recess 16 to the bottom side of the recess 16, which is hereinafter referred to as the opening side dimension. Another dimension is the longitudinal width of the recess 16 at a position that is a certain distance away from the horizontal wall 23 of the recess 16 to the opening of the recess 16, which is hereinafter referred to as the bottom side dimension.

[0092] In the evaluation test, a plurality of recesses 16 of a specified layer among the recesses 16 formed in multiple layers are set as the recesses 16 at the top. The groove width dimension, the opening side dimension, and the bottom side dimension of the recess 16 at the top are calculated (dimension after etching - dimension before etching) / 2. This calculation is performed for each of the plurality of recesses 16 at the top. Moreover, for the calculated value obtained based on the groove width dimension, the calculated value obtained based on the opening side dimension, and the calculated value obtained based on the bottom side dimension, the average value of the calculated values ​​between the recesses 16 is calculated, and the obtained average value is set as the groove width etching amount, the opening side etching amount, and the bottom side etching amount of the recess 16 at the top. In addition, the groove width dimension of each recess 16 at the top is obtained between the upper walls 21 of the recesses 16 facing each other in the transverse direction.

[0093] Similarly, the plurality of concave portions 16 of a predetermined layer are respectively set as the middle concave portion 16 and the bottom concave portion 16, and the groove width etching amount, the opening side etching amount, and the bottom side etching amount of the middle concave portion 16 and the bottom concave portion 16 are also calculated respectively. Figure 13 to Figure 15 The values ​​obtained by dividing the calculated etching amounts by a predetermined reference amount are recorded in the standardization. The larger the standardized value is, the larger the actual etching amount is. In addition, the etching amounts (i.e., measured values) obtained in each evaluation test before test standardization are values ​​below 20 nm.

[0094] In addition, as the test results of evaluation tests 3 to 5, a table recording the shape of the concave portion 16 after etching and the state of the roughness of the concave portion 16 is shown. In each table, the case where a clear rectangular shape is shown and the case where a clear circular shape is shown are respectively indicated as "rectangular" and "circular", and the case of other shapes is indicated as "middle". Therefore, in the table, although it is not a clear rectangular shape, the rectangularity is relatively high and the shape at a level that is not a problem in practical use is also indicated as "middle", so not only the processing conditions that result in a "rectangular" are practical processing conditions. In addition, in the table, the case where neither the micro-roughness nor the large roughness is confirmed and the smoothness is high is indicated as "smooth".

[0095] Evaluation test 1

[0096] In evaluation tests 1-1 to 1-3, the substrate is etched by repeating a cycle of a process gas supply process and a heating process. Between evaluation tests 1-1 to 1-3, the combination of the number of cycles and the pressure in the process container 71 when the process gas supply process is performed is changed. In evaluation test 1-1, the pressure in the process container 71 is 200 Pa (1.5 Torr), and the number of cycles is 9. In evaluation test 1-2, the pressure in the process container 71 is 666.6 Pa (5 Torr), and the number of cycles is 9. In evaluation test 1-3, the pressure in the process container 71 is 666.6 Pa (5 Torr), and the number of cycles is 3. Each processing condition, such as the temperature of the wafer W during the process gas supply, the supply time of the process gas, and the flow ratio of the NH3 gas, is set to a value within the range described in the embodiment.

[0097] The result of the evaluation test 1 shows the average value of the values ​​obtained from each concave portion 16 at the top, middle, and bottom. In the evaluation test 1-1, the groove width etching amount was 1.26, the opening side etching amount was 1.62, and the bottom side etching amount was 1.66. In the evaluation test 1-2, the etching progressed greatly, and the upper wall 21 and the lower wall 22 disappeared, and each etching amount could not be measured. In the evaluation test 1-3, the disappearance of the upper wall 21 and the lower wall 22 was prevented, and the groove width etching amount was 1.78, the opening side etching amount was 1.9, and the bottom side etching amount was 1.9.

[0098] According to the results of the above evaluation test 1, it can be seen that the etching rate can be increased by making the pressure in the processing container 71 relatively high when the processing gas is supplied, which is preferred, and excessive etching can be prevented by appropriately setting the number of cycles. It can also be seen that the pressure in the processing container 71 is preferably greater than 1.5 Torr (200 Pa), and more preferably greater than 5 Torr (666.6 Pa).

[0099] Evaluation test 2

[0100] In evaluation tests 2-1 to 2-5, the process gas supply process and the heating process were not repeated, and each substrate was processed by performing these processes only once. Between evaluation tests 2-1 to 2-5, the supply time of the process gas was set to different values, and in evaluation tests 2-1, 2-2, 2-3, 2-4, and 2-5, it was set to 5 seconds, 10 seconds, 15 seconds, 25 seconds, and 35 seconds, respectively. In addition, each process condition such as the flow ratio of NH3 gas, the temperature of the wafer W during the process gas supply, and the pressure in the process container 71 was set to a value within the range described in the embodiment.

[0101] The following Figure 13 to Figure 15The graphs of summarize the etching amounts in the evaluation test 2. Each graph shows the relationship between the etching amount and the supply time of the processing gas, with the vertical axis representing the etching amount and the horizontal axis representing the supply time. Fig.13 Indicates the amount of groove width etching, Fig.14 Indicates the amount of etching on the opening side, Fig.15 Indicates the bottom side etch amount.

[0102] according to Fig.13 It is clear from the graph that regarding the etching amount in the lateral direction of the groove 15, the correlation between the supply time of the processing gas at the top, middle, and bottom parts and the etching amount is low. Fig.14 and Fig.15 As is clear from the graph of , when the etching time is long, the etching amount on the top side is small, regarding the etching amount on the opening side of the recess 16 and the etching amount on the bottom side of the recess 16. This is considered to be because a large amount of AFS is generated on the top side as described in the embodiment. Fig.14 and Fig.15 As described in the embodiment, the graph of shows that when the etching time is short, the etching amount at the top is large, and when the etching time is long, the etching amount at the bottom is large. Fig.14 , Fig.15 In the curve graph, when the supply time of the processing gas is within the range of 10 seconds to 15 seconds at the top, middle, and bottom, the slope of the curve graph is substantially the same, and the difference in the etching amount at the top, middle, and bottom is suppressed. Therefore, according to the evaluation test 2, the supply time of the processing gas in one cycle is preferably 10 seconds to 15 seconds.

[0103] Evaluation test 3

[0104] In evaluation tests 3-1 to 3-6, each substrate was processed by making the combination of the flow ratio of NH3 gas and the supply time of the processing gas different for each substrate. The number of cycles was set to three cycles. Regarding the supply time of the processing gas, it was set to 10 seconds in evaluation tests 3-1 to 3-3, and to 15 seconds in evaluation tests 3-1 to 3-3. Regarding the flow ratio of NH3 gas, it was set to 0.01 in evaluation tests 3-1 and 3-4, to 0.014 in evaluation tests 3-2 and 3-5, and to 0.02 in evaluation tests 3-3 and 3-6. The other processing conditions are the same as those of evaluation test 2. The following Table 1 summarizes the results obtained in evaluation test 3. In addition, in this evaluation test 3, the etching amount of each part was obtained in the same way as in evaluation test 2.

[0105] [Table 1]

[0106] [Table 1]

[0107]

[0108] The roughness of the upper wall 21 and the lower wall 22 of the concave portion 16 after etching was observed, and minute roughness was confirmed in each concave portion 16 in the middle and bottom of the evaluation test 3-1. Moreover, large roughness was confirmed in the concave portion 16 at the top of the evaluation test 3-3 and each concave portion 16 at the top, middle, and bottom of the evaluation test 3-6. In addition, the shape of the concave portion 16 after etching was observed, and each concave portion 16 at the top, middle, and bottom of the evaluation tests 3-1 and 3-4 and the concave portion 16 at the bottom of the evaluation test 3-2 became a rectangular shape.

[0109] Therefore, according to the evaluation test 3, it can be confirmed that when the flow rate of NH3 gas is relatively small and the etching time is short, a small roughness is formed. In addition, it can be confirmed that when the flow rate of NH3 gas is relatively large, a large roughness is formed. It can be considered that since the amount of AFS generated is different as described in the embodiment, the roughness state is different as a result. In addition, according to the evaluation test 3, it can be confirmed that when the flow rate of NH3 gas is relatively small, there is a tendency to become a rectangular shape. And it can be seen that in order to form a rectangular shape, it is preferred to make the flow ratio less than 0.014, and more preferably less than 0.01.

[0110] However, in evaluation tests 3-1, 3-4, and 3-5 in which the flow rate ratio of NH3 gas was set to 0.01 to form a rectangular shape, the top-bottom etching amount had a large deviation. Therefore, the results of each of the evaluation tests 3-1 to 3-6 did not fully meet one or more of the first to third requirements.

[0111] Evaluation test 4

[0112] In evaluation tests 4-1 to 4-5, the combination of the flow ratio of NH3 gas, the supply time of the processing gas, and the number of cycles was made different according to the substrate to process each substrate. Regarding the supply time of the processing gas, it was set to 10 seconds, 15 seconds, 15 seconds, 12.5 seconds, and 10 seconds in evaluation tests 4-1, 4-2, 4-3, 4-4, and 4-5, respectively. Regarding the flow ratio of NH3 gas in the processing gas, it was set to 0.01 in evaluation tests 4-1, 4-2, and 4-4, and to 0.014 in evaluation tests 4-3 and 4-5. Regarding the number of cycles, it was set to 3 in evaluation tests 4-1 to 4-4, and to 4 in evaluation test 4-5. Other processing conditions are the same as those of evaluation tests 2 and 3. The following Table 2 summarizes the results of evaluation test 4. In addition, in this evaluation test 4 and the evaluation test 5 described below, the etching amount of each part was obtained in the same way as in evaluation test 3.

[0113] [Table 2]

[0114] [Table 2]

[0115]

[0116] By observing the roughness of the upper wall 21 and the lower wall 22 of the concave portion 16 after etching, micro roughness was confirmed in each concave portion 16 in the middle and bottom of the evaluation tests 4-1 and 4-4 and the concave portion 16 at the bottom of the evaluation test 4-5. The roughness of the other concave portions 16 was suppressed within the desired range. By comparing the evaluation tests 4-1, 4-2, and 4-4 with the same cycle number and NH3 gas flow rate ratio, it can be seen that, as described in the embodiment, when the supply time of the processing gas is short, micro roughness is easily formed.

[0117] Observing the shape of the concave portion 16 after etching, the concave portions 16 at the top, middle, and bottom of the evaluation tests 4-1 and 4-2 and the concave portions 16 at the middle and bottom of the evaluation tests 4-4 and 4-5 became rectangular shapes, and the other concave portions 16 became circular shapes. By comparing the evaluation tests 4-1, 4-2, and 4-4, it can be seen that, as described in the embodiment, when the supply time of the processing gas is small, there is a tendency to become a rectangular shape. In addition, in the evaluation tests 4-1, 4-2, and 4-4 in which the flow ratio of the NH3 gas is set to 0.01, two or three of the top, middle, and bottom become rectangular shapes, so it can be seen that in order to form a rectangular shape, it is preferably set to less than 0.01.

[0118] Observing the etching amount on the opening side and the etching amount on the bottom side, in evaluation tests 4-2, 4-4, and 4-5, the etching amount on the top is greater than the etching amount on the middle and bottom. In other words, there is a relatively large deviation in the etching amount between the top, middle, and bottom. In addition, in evaluation test 4-3, the etching amount on the top is less than the etching amount on the middle and bottom. Due to the above results, the recesses 16 of each substrate of evaluation test 4 cannot fully meet one or more of the first to third requirements.

[0119] In addition, the results of the evaluation test 4 were further verified. When the flow ratio of the NH3 gas was 0.01, the recess 16 tended to become a rectangular shape, and the etching amount at the top tended to increase. In addition, when the flow ratio of the NH3 gas was 0.014, the recess 16 showed a tendency to become a circular shape, and the tendency of the etching amount at the top to increase was alleviated compared to the case where the flow ratio was 0.01. Moreover, when the flow ratio of the NH3 gas was 0.01 and 0.014, the roughness was sometimes suppressed within the desired range. However, when the flow ratio of the NH3 gas in the processing gas was set to 0.01 and 0.014, the roughness did not obtain the desired result when the supply time of the processing gas was 10 seconds.

[0120] Considering the results of the above evaluation test 4 and the results of the evaluation test 2 that the supply time of the desired processing gas is 10 seconds to 15 seconds, it is conceivable to set the flow ratio of the NH3 gas in the processing gas to a range greater than 0.01 and less than 0.014, and set the supply time of the processing gas to a range greater than 10 seconds and less than 15 seconds. In other words, it is conceivable to search for an allowable range that can better meet the first requirement to the third requirement compared to the processing conditions set in the evaluation test 4 in the range of each parameter, and use the value within the allowable range for processing. However, with respect to the flow ratio of the NH3 gas, a smaller range in a relatively small range such as 0.01 to 0.014 is set as the allowable range. Therefore, for example, in the case where the film structure as the etching object has undergone a slight change, it is difficult to change the flow ratio to cope with it, and the practicality may be low. Therefore, it is effective to perform multiple stages of processing by changing the processing conditions as described in the embodiment.

[0121] Evaluation test 5

[0122] In evaluation tests 5-1 to 5-5, two-stage processing (= front-stage cycle and back-stage cycle) was performed by changing the processing conditions as described in the embodiment. The processing conditions of the front-stage cycle and the combination of the processing conditions of the back-stage cycle were changed for each substrate. In addition, the processing conditions other than the flow rate ratio of NH3 gas, the supply time of the processing gas, and the number of cycles were the same as those of evaluation test 4.

[0123] The flow rate ratio of NH3 gas and the supply time of the processing gas in the first cycle of the evaluation test 5-1, 5-2, and 5-4 and the second cycle of the evaluation test 5-3 and 5-5 were set to the same processing conditions as those under which the rectangular shape was obtained in the evaluation test 4. In addition, the flow rate ratio of NH3 gas and the supply time of the processing gas in the second cycle of the evaluation test 5-1, 5-2, and 5-4 and the first cycle of the evaluation test 5-3 and 5-5 were set to the same processing conditions as those under which the roughness was suppressed within the desired range in the evaluation test 4. The following Table 3 summarizes the processing conditions and results of the evaluation test 5.

[0124] In addition, in addition to the flow rate ratio of NH3 gas and the supply time of the processing gas, the difference in the number of cycles was taken into consideration. As for the tendency to form a rectangular shape, the first stage of evaluation test 5-1> the first stage of evaluation test 5-2 and the second stage of 5-3> the first stage of evaluation test 5-4> the second stage of evaluation test 5-5. Moreover, as for the tendency to suppress roughness, the second stage of evaluation test 5-2, the first stage of 5-3, and the first stage of 5-5> the second stage of evaluation test 5-1 and the second stage of 5-4.

[0125] [Table 3]

[0126] [Table 3]

[0127]

[0128] Regarding the results of evaluation tests 5-1 to 5-5, the difference in etching amount between the top and bottom is verified. The outline of this verification is described, and the difference in etching amount of the recess 16 between the top and bottom obtained according to evaluation test 4 is corrected according to the number of cycles. Thus, the estimated difference in etching amount between the top and bottom when only the front-stage cycle is performed in evaluation test 5 and the estimated difference in etching amount between the top and bottom when only the rear-stage cycle is performed in evaluation test 5 are calculated respectively. The estimated etching amount difference is added together to obtain the estimated etching amount difference between the top and bottom. The estimated etching amount difference and the estimated etching amount difference obtained in the process of obtaining the estimated etching amount difference are compared with the actual etching amount difference between the top and bottom obtained according to evaluation test 5.

[0129] The following is a specific description. In the evaluation test 5-1, the etching amount of the opening side and the etching amount of the bottom side of the top are respectively set to A1X1 and A2X2, and their average value is set to A3X3. The etching amount of the opening side and the etching amount of the bottom side are respectively set to B1Y1 and B2Y2, and their average value is set to B3Y3. The value obtained by calculating A3X3-B3Y3 is used as the difference in etching amount between the top and the bottom in the evaluation test 5-1. In addition, the difference in etching amount between the top and the bottom calculated in this way is a positive value. Therefore, in the evaluation test 5-1, the etching amount of the top is large between the top and the bottom.

[0130] Except for the number of cycles, evaluation tests 4-1 and 4-3 were respectively carried out under the same conditions as the front and rear cycles of evaluation test 5-1. For evaluation test 4-1, (the average value of the etching amount on the opening side of the top and the etching amount on the bottom side of the top)-(the average value of the etching amount on the opening side of the bottom and the etching amount on the bottom side) = C1A1 was obtained. The number of cycles in evaluation test 4-1 was 3, but the number of front-stage cycles in evaluation test 5-1 was 4, so correction was performed by multiplying by 4 / 3, and the obtained value was set to the estimated etching amount difference C2A2 (= C1A1 × 4 / 3). In addition, the value of C2A2 is a positive value. That is, between the top and the bottom, the etching amount at the top is large.

[0131] Moreover, for evaluation test 4-3 with the same conditions as the latter cycle, the difference in the estimated etching amount is also calculated in the same way. Specifically, for evaluation test 4-3, (the average value of the etching amount on the opening side of the top and the etching amount on the bottom side of the top) - (the average value of the etching amount on the opening side of the bottom and the etching amount on the bottom side of the bottom) = C1A′1 is calculated. The number of cycles in evaluation test 4-3 is 3, but the number of latter cycles in evaluation test 5-1 is 1, so correction is made by multiplying by 1 / 3, and this value is set to the difference in the estimated etching amount C2A′2 (= C′A′1×1 / 3). This C2A′2 is a negative value. That is, between the top and the bottom, the etching amount at the bottom is larger.

[0132] The total estimated etching amount C2A2+C2A′2 is compared with A3X3-B3Y3 of evaluation test 5-1, and they are approximately the same value. In addition, C2A2 is larger than A3X3-B3Y3. The above calculation results show that when performing the two-stage processing described in the embodiment, even if a relatively large deviation in the etching amount occurs between the top side and the bottom side at the end of the first stage of processing, as the second stage of processing, the deviation can be offset by performing a process that increases the top side and the bottom side opposite to the first stage of processing.

[0133] In addition, as described above, in the evaluation test 4-1, each recess 16 was rectangular in shape, and a small roughness was formed in the recess 16 in the middle and bottom. In the evaluation test 4-3, each recess 16 was an intermediate shape, and the roughness of each recess 16 was within the desired range. In contrast, as the test result of the evaluation test 5-1, the recess 16 in the middle and bottom was rectangular in shape, and a small roughness was confirmed in each recess 16 at the top, middle, and bottom. Therefore, the shape and roughness of the recess 16 became the result that the influence of the processing conditions of the previous cycle was relatively large.

[0134] Evaluation Tests 5-2 to 5-5 were also verified based on the above calculations in the same manner as Evaluation Test 5-1, and the result was that it was estimated that the deviation in the etching amount between the top side and the bottom side was offset by implementing the front-stage cycle and the back-stage cycle. In addition, when performing the verification, the processing conditions of Evaluation Tests 4-1 and 4-3 were used in Evaluation Tests 5-2 and 5-3 in the same manner as Evaluation Test 5-1, but the processing conditions of Evaluation Test 4-2 were used in Evaluation Tests 5-4 and 5-5, so the data of Evaluation Test 4-2 were used for verification.

[0135] In addition, the front-stage cycle and the back-stage cycle of the evaluation test 5-2 are the same as those of the evaluation test 5-1, and the processing conditions are the same as those of the evaluation tests 4-1 and 4-3, respectively, except for the number of cycles. Moreover, as shown in Table 3, in the evaluation test 5-2, the concave portion 16 at the bottom is rectangular, and micro-roughness is confirmed in each concave portion 16 in the middle and the bottom. Therefore, in the evaluation test 5-2, as in the evaluation test 5-1, the shape and roughness of the concave portion 16 become the result that the influence of the processing conditions of the front-stage cycle is relatively large.

[0136] Regarding evaluation test 5-3, the front-stage cycle and the back-stage cycle are the same as evaluation test 4-3 and evaluation test 4-1, respectively, except for the number of cycles. Moreover, as shown in Table 3, in evaluation test 5-3, each recess 16 at the top, middle, and bottom becomes an intermediate shape, and on the other hand, the roughness is suppressed within the allowable range. Moreover, in evaluation test 4-3, each recess 16 is an intermediate shape, and the roughness of each recess 16 converges within the allowable range, on the other hand, in evaluation test 4-1, each recess 16 is a rectangular shape, and the recesses 16 in the middle and bottom are formed with a small roughness. Therefore, in this evaluation test 5-3, the shape and roughness of the recess 16 also become the result that the influence of the processing conditions of the front-stage cycle is relatively large.

[0137] Regarding evaluation test 5-4, the front-stage cycle and the back-stage cycle are the same as evaluation test 4-2 and evaluation test 4-3, respectively, except for the number of cycles. As shown in Table 3, in evaluation test 5-4, the recess 16 at the bottom is rectangular in shape, and a slight roughness is confirmed in the recess 16 at the bottom. On the other hand, in evaluation test 4-2, each recess 16 is rectangular in shape, and a slight roughness is formed in the recess 16 at the bottom. Moreover, in evaluation test 4-3, each recess 16 is an intermediate shape, and the roughness of each recess 16 converges within the desired range. Therefore, in this evaluation test 5-4, the shape and roughness of the recess 16 also become the result of the relatively large influence of the processing conditions of the front-stage cycle.

[0138] Regarding evaluation test 5-5, the front-stage cycle and the back-stage cycle are the same as evaluation test 4-3 and evaluation test 4-2, respectively, except for the number of cycles. In addition, as described above, in evaluation test 5-5, the roughness of each concave portion 16 at the top, middle, and bottom is suppressed within the allowable range, and each concave portion 16 is an intermediate shape. On the other hand, in evaluation test 4-3, each concave portion 16 is an intermediate shape, and the roughness of each concave portion 16 converges within the desired range. Moreover, in evaluation test 4-2, each concave portion 16 is a rectangular shape, and the concave portion 16 at the bottom is formed with a small roughness. Therefore, in this evaluation test 5-5, the shape and roughness of the concave portion 16 also become the result of the relatively large influence of the processing conditions of the front-stage cycle. However, in this evaluation test 5-5, the roughness of the top, middle, and bottom is suppressed, and the difference A3X3-B3Y3 in the etching amount between the top and the bottom is the smallest in evaluation test 5. The shape of each recess 16 is slightly closer to a circular shape than the shape of the recess 16 in the evaluation test 5-1, but has a higher rectangularity than the shape of each recess 16 in the evaluation test 4-3 and is practical. Therefore, among the evaluation tests 5-1 to 5-5, the evaluation test 5-5 is the most preferable result.

[0139] As described above, according to evaluation test 5, it can be confirmed that the deviation of the etching amount between the top side and the bottom side in the front cycle and the rear cycle is offset, and as a result, the uniformity of the etching amount from the top side to the bottom side can be improved. In addition, it can be confirmed that the processing conditions performed in the front cycle have a greater influence on the shape and roughness of the recessed portion 16 after etching. Moreover, as described so far, in evaluation tests 5-3 and 5-5, the roughness is suppressed at the top, middle and bottom, respectively. Therefore, it is shown that in order to suppress the roughness in this way, as described in the embodiment, it is preferred to make the flow ratio of NH3 gas in the first processing condition of the front cycle greater than the flow ratio of NH3 gas in the second processing condition of the rear cycle. When comparing evaluation tests 5-3 and 5-5, the difference in etching amount between the top and the bottom is different, and the difference in etching amount in evaluation test 5-5 is small. Since the supply time of the processing gas in the second processing condition is different between evaluation tests 5-3 and 5-5, it can be seen that by adjusting the supply time of the processing gas between the first processing condition and the second processing condition, the roughness of each recess 16 can be suppressed and the balance of the etching amount between the top, middle and bottom can be controlled.

[0140] In addition, the rectangularity of the concave portion 16 is described. According to the results of the evaluation tests 5-1, 5-2, and 5-4, in order to improve the rectangularity, it is preferable to make the flow rate ratio of the NH3 gas in the first processing condition smaller than the flow rate ratio of the NH3 gas in the second processing condition. In addition, since the rectangularity of the evaluation test 5-1 is the highest, it is shown that in order to obtain a higher rectangularity, it is preferable to make the supply time of the processing gas in the first processing condition shorter than the supply time of the processing gas in the second processing condition.

[0141] Description of Reference Numerals

[0142] W: wafer; 12: SiGe film; 13: Si film; 41: F2 gas; 42: NH3 gas.

Claims

1. A substrate processing method, comprising the following steps: In a first step, a processing gas containing a halogen-containing gas and an alkaline gas is supplied to a substrate having a concave portion formed with a side wall formed of a silicon film and a bottom wall formed of a germanium-containing film, so as to modify the surface of the silicon film to generate a reaction product; A second step of removing the reaction product to increase the width of the recess; A step of performing a cycle consisting of the first step and the second step a plurality of times; as well as The first step of the cycle that is performed first is performed under a first processing condition, and the first step of the cycle that is performed later is performed under a second processing condition that is different from the first processing condition.

2. The substrate processing method according to claim 1, wherein: The first processing condition and the second processing condition differ in at least one of a ratio of the alkaline gas to the halogen-containing gas in the processing gas and a supply time of the processing gas.

3. The substrate processing method according to claim 2, wherein: The first process condition has a smaller ratio of the alkaline gas to the halogen-containing gas than the second process condition, or the first process condition has a shorter supply time of the process gas than the second process condition.

4. The substrate processing method according to claim 2, wherein: The first process condition has a larger ratio of the alkaline gas to the halogen-containing gas than the second process condition, or the first process condition has a longer supply time of the process gas than the second process condition.

5. The substrate processing method according to claim 3 or 4, wherein: The recessed portion is formed in multiple layers in the thickness direction of the substrate. The plurality of recesses are respectively opened in a direction intersecting the thickness direction.

6. The substrate processing method according to claim 2, wherein: The halogen-containing gas is a first fluorine-containing gas, and the alkaline gas is ammonia.

7. The substrate processing method according to claim 6, wherein: The first fluorine-containing gas is fluorine gas.

8. The substrate processing method according to claim 1, wherein: The germanium-containing film is a silicon germanium film.

9. The substrate processing method according to claim 2, wherein: In one of the first processing condition and the second processing condition, a ratio of the alkaline gas to the halogen-containing gas is less than 0.

014.

10. The substrate processing method according to claim 2, wherein: In the first processing condition and the second processing condition, the supply time of the processing gas is 10 seconds to 15 seconds.

11. The substrate processing method according to claim 10, wherein: The first step includes supplying the processing gas into the processing container in a state where the pressure in the processing container accommodating the substrate is greater than 200 Pa.

12. The substrate processing method according to claim 1, wherein: The first process includes the following steps: a first supplying step of supplying the halogen-containing gas to the substrate and supplying the alkaline gas to the substrate in parallel; as well as The second supplying step is performed after the first supplying step, and includes supplying only one of the halogen-containing gas and the alkaline gas to the substrate.

13. The substrate processing method according to claim 12, wherein: The halogen-containing gas is composed of a first fluorine-containing gas supplied to the substrate in the first supply step and a second fluorine-containing gas supplied to the substrate in the second supply step. The first fluorine-containing gas and the second fluorine-containing gas are of different types.

14. The substrate processing method according to claim 13, wherein: The first fluorine-containing gas is fluorine gas, The second fluorine-containing gas is hydrogen fluoride gas.

15. A substrate processing device comprising: A first processing section that supplies a processing gas including a halogen-containing gas and an alkaline gas to modify the surface of the silicon film in a substrate having a concave portion having a side wall formed of a silicon film and a bottom wall formed of a germanium-containing film to generate a reaction product; a second processing part for removing the reaction product to enlarge the width of the recess; as well as A control unit that outputs a control signal to perform a cycle consisting of the processing of the first processing unit and the processing of the second processing unit multiple times, and performs the processing of the first processing unit of the cycle that is performed first under a first processing condition, and performs the processing of the first processing unit of the cycle that is performed later under a second processing condition that is different from the first processing condition.

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