Etching methods and etching apparatus

Abstract

In an etching method that supplies etching gas to a substrate to etch a surface, the following steps are performed: a protection step in which amine gas is supplied to the substrate on which an oxygen-containing silicon film is disposed, to form a protective film on the surface of the oxygen-containing silicon film to prevent it from being etched by the etching gas; and a first etching step in which the amine gas and a first etching gas, which is one of the etching gases, are supplied to the substrate to etch the oxygen-containing silicon film, wherein the first etching gas is a fluorine-containing gas.

Description

Technical Field

[0001] This disclosure relates to an etching method and etching apparatus. Background Technology

[0002] When constructing a semiconductor device, various films formed on a semiconductor wafer (hereinafter referred to as a wafer) that serves as a substrate are etched. For example, in Patent Document 1, it is described that a wafer on which an interlayer insulating film, called a low-k film, is formed is etched to form a recess in the interlayer insulating film for embedding wiring.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-63141 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This disclosure provides a technique for freely switching between protection and etching relative to etching gases on an oxygen-containing silicon film formed on a substrate.

[0008] Solution for solving the problem

[0009] The etching method disclosed herein supplies an etching gas to a substrate to etch the surface. The etching method includes the following steps: a protection step, in which an amine gas is supplied to the substrate on which an oxygen-containing silicon film is disposed to form a protective film on the surface of the oxygen-containing silicon film to prevent it from being etched by the etching gas; and a first etching step, in which the amine gas and a first etching gas, which is one of the etching gases, are supplied to the substrate to etch the oxygen-containing silicon film, wherein the first etching gas is a fluorine-containing gas.

[0010] The effects of the invention

[0011] This disclosure enables the flexible switching of protection and etching relative to etching gases for oxygen-containing silicon films formed on substrates. Attached Figure Description

[0012] Figure 1 This is a longitudinal sectional side view of the surface of a wafer on which an etching and protective film is formed, as per one embodiment of this disclosure.

[0013] Figure 2A This is a process diagram illustrating the etching process.

[0014] Figure 2B This is a process diagram illustrating the etching process.

[0015] Figure 2CIt is a process diagram illustrating the described etching.

[0016] Figure 3A It is a process diagram illustrating the described etching.

[0017] Figure 3B It is a process diagram illustrating the described etching.

[0018] Figure 4A It is a process diagram illustrating the described etching.

[0019] Figure 4B It is a process diagram illustrating the described etching.

[0020] Figure 5A It is a process diagram illustrating the described etching.

[0021] Figure 5B It is a process diagram illustrating the described etching.

[0022] Figure 6A It is a process diagram illustrating the described etching.

[0023] Figure 6B It is a process diagram illustrating the described etching.

[0024] Figure 7 It is a longitudinal sectional side view of the surface of the wafer W after the described etching.

[0025] Figure 8 It is a timing chart (Japanese: チャート図) showing an example of the supply timing of each gas.

[0026] Figure 9 It is a timing chart showing an example of the supply timing of each gas.

[0027] Figure 10 It is a timing chart showing an example of the supply timing of each gas.

[0028] Figure 11 It is a top view of a substrate processing apparatus for performing etching.

[0029] Figure 12 It is a longitudinal sectional side view of an etching module provided in the substrate processing apparatus.

[0030] Figure 13 It is an explanatory diagram showing another embodiment of etching and the formation of a protective film.

[0031] Figure 14 It is a bar chart showing the results of an evaluation test.

[0032] Figure 15 It is a bar chart showing the results of an evaluation test. [[ID=The detailed implementation method]]

[0033] The following describes the processing involved in one embodiment of the etching method of this disclosure. Figure 1 This diagram shows a longitudinal sectional side view of the surface portion of the wafer W to which this treatment is performed. A silicon oxide (SiOx) film 12, a SiOCN film 13, a polysilicon film 14, and a silicon oxide film 15 are formed on the lower layer film 11 of the wafer W. Recesses are formed in the lower layer film 11 and the silicon oxide film 12, and a stacked film composed of the silicon oxide film 15 and the polysilicon film 14 is embedded within these recesses. This stacked film is formed by covering the silicon oxide film 15 with the polysilicon film 14. In other words, the silicon oxide film 12 is disposed on the lower side, and the polysilicon film 14 is disposed on the upper side.

[0034] Furthermore, a SiOCN film 13 (i.e., a film composed of silicon, oxygen, nitrogen, and carbon) is disposed between the sidewalls of the aforementioned laminated film and the sidewalls of the recess, such that it surrounds the side of the laminated film and is in contact with both the sidewalls of the laminated film and the sidewalls of the recess. Therefore, the SiOCN film 13 is disposed between the laminated film (silicon oxide film 15 and polycrystalline silicon film 14) and the silicon oxide film 12. That is, these films are disposed in a laterally adjacent manner in the order of the laminated film, the SiOCN film 13, and the silicon oxide film 12, with the pores of the SiOCN film 13 opening into both the laminated film and the silicon oxide film 12.

[0035] Polycrystalline silicon film 14, SiOCN film 13, and silicon oxide film 12 are exposed on the surface of wafer W. The aforementioned SiOCN film 13 is an interlayer insulating film, also known as a low-k film, and is a porous film. Silicon oxide film 15 is a second silicon film containing oxygen, silicon oxide film 12 is a first silicon film containing oxygen, and SiOCN film is a third silicon film containing oxygen.

[0036] The general outline of this embodiment will be described. In this embodiment, after a second etching process is performed to etch the polysilicon film 14, which is the etched film, a first etching process is performed to etch the silicon oxide film 15. First, an etching gas 21 for the polysilicon film 14 is supplied to the wafer W. This etching gas 21 is, for example, a mixture of ClF3 (chlorine trifluoride) gas, F2 (fluorine) gas and NH3 (ammonia) gas, or IF7 (iodine heptafluoride) gas. The polysilicon film 14, silicon oxide films 12, and 15 are all etchable relative to this etching gas 21, which is the second etching gas. The silicon oxide film 12 and the SiOCN film 13 are non-etchable films that are not desired to be etched.

[0037] In this embodiment, during etching using the etching gas 21 described above, amine gas is supplied to the wafer W. As shown in the evaluation test described later, the adsorption capacity of amine relative to the silicon oxide film 12 and the SiOCN film 13 is higher than that of amine relative to the polycrystalline silicon film 14, and amine hardly adsorbs onto the polycrystalline silicon film 14. Utilizing this difference in adsorption capacity, a protective process is performed as follows: by supplying amine gas to the wafer W, a protective film composed of amine contained in the amine gas is selectively formed on the silicon oxide film 12 and the SiOCN film 13, as well as the polycrystalline silicon film 14. With this protective film formed, the etching gas 21 described above is supplied to the wafer W to selectively etch the polycrystalline silicon film 14.

[0038] Furthermore, the amine adsorbs onto the pore walls of the SiOCN film 13, blocking the pores and preventing the passage of etching gas 21 within them. Therefore, it also forms a protective film within the pores of the SiOCN film 13. This prevents etching gas 21 from being supplied through the pores to the sidewalls of the silicon oxide film 12 from the recesses on the wafer W surface formed by etching the polysilicon film 14, thus preventing the sidewalls from being etched.

[0039] While the polysilicon film 14 is etched in this protective film state, the etching gas supplied to the wafer W is switched from etching gas 21 to HF (hydrogen fluoride) gas 22, which is used as the etching gas for the silicon oxide film, when the silicon oxide film 15 is exposed. Amine gas is also supplied to the wafer W during the etching of the silicon oxide film 15, but this amine gas reacts with HF gas 22 to promote the etching of the silicon oxide film 15. Thus, in this embodiment, the treatment of the silicon oxide film using amine gas is switched between protection and etching depending on the presence or absence of HF gas supply.

[0040] Next, referring to Figures 2 through 6, the processing performed on wafer W will be described in more detail in sequence. These Figures 2 through 6 illustrate the processing performed on wafer W. Figure 1 The diagrams illustrate how the surface of wafer W changes due to processing. The processing shown in these figures is performed under a vacuum atmosphere at a predetermined pressure, where wafer W is placed into a processing container and the container is evacuated. In the figures, the aperture formed on the SiOCN film 13 is designated as 16. Furthermore, in the following description, the amine supplied to wafer W will be designated as 23. In this embodiment, amine 23 is, for example, butylamine (C4H4H4O2). 11The amine 23 described above is supplied to the wafer W as a gas, as already described, and adsorbs onto the respective surfaces of the SiOCN film 13 and the silicon oxide film 12. However, the adsorption is not limited to a gas; it can also be a solid or a liquid. Furthermore, as already described, a protective film is formed by the adsorbed amine 23, but this protective film is shown as 24 in the figure. Therefore, for convenience, the amine adsorbed on the wafer W is represented as the protective film 24 in the figure to distinguish it from the amine 23 not adsorbed on the wafer W.

[0041] First, amine gas is supplied into the processing container as amine 23 (step S1). Figure 2A , Figure 2B As described above, amine 23 readily adsorbs onto the SiOCN film 13 and the silicon oxide film 12, thus the adsorption of amine 23 progresses to the surface (upper surface) of these films, forming a protective film 24. Furthermore, compared to the silicon oxide film 12, amine 23 has a higher adsorption capacity relative to the SiOCN film 13, therefore the protective film 24 is formed relatively thickly on the SiOCN film 13, although this thickness difference is omitted in the figures. While forming the protective film 24 in this way, on the other hand, amine 23 adsorbs onto the pore walls of the SiOCN film 13 and remains in the pores 16, blocking the pores 16. Therefore, as described above, the protective film 24 is also formed in the pores 16.

[0042] Next, the supply of amine gas to the processing container is stopped, and the processing container is placed in a state where exhaust gas and the supply of purging gas, such as N2 (nitrogen), are carried out (step S2). Figure 2C Thus, amine gas that did not flow into the orifice 16 and did not form a protective film 24 is removed by the flow of the exhaust purging gas.

[0043] Next, etching gas 21 is supplied into the processing container to etch the polysilicon film 14 that is not covered by the protective film 24, thereby exposing the upper sidewall of the SiOCN film 13 (step S3). Figure 3A On the other hand, the protective film 24 prevents the SiOCN film 13 and the silicon oxide film 12 from being etched from the top. Furthermore, since the aperture 16 on the upper side of the SiOCN film 13 is blocked by amine 23, etching gas 21 is also prevented from being supplied to the sidewall of the silicon oxide film 12 through the aperture 16. In other words, etching of this sidewall is prevented. Afterwards, the supply of etching gas 21 to the processing container is stopped, and the processing container is placed in a state where exhaust and purging gases are supplied (step S4). Figure 3B The etching gas 21 remaining in the processing container is removed by the airflow of purge gas exhausted from the processing container.

[0044] Next, amine gas is supplied into the processing container. That is, step S1 is performed again. In step S3 above, the polysilicon film 14 is etched, thereby exposing the upper sidewall of the SiOCN film 13. Therefore, the amine 23 in the gas supplied in this second step S1 is supplied to the pore 16 in the SiOCN film 13 that is lower than the pore 16 in the first step S1, and is adsorbed onto the pore wall, thus blocking the pore 16. Figure 4A Additionally, a protective film 24 is also formed on the exposed sidewalls of the SiOCN film 13.

[0045] Next, the exhaust and purging gases in the processing container are supplied again in step S2. Then, in step S3, the etching gas 21 is supplied to the processing container to further etch the polysilicon film 14 downwards, expanding the exposed area in the sidewall of the SiOCN film 13 downwards. At this time, similar to the first etching, the protective film 24 prevents the SiOCN film 13 and the silicon oxide film 12 from being etched from the top.

[0046] Furthermore, through the second step S1, the region in the SiOCN film 13 where the amine 23 is supplied extends downwards, thereby retaining the amine 23 as a protective film 24 near the newly exposed sidewalls of the SiOCN film 13 due to the etching of the polysilicon film 14. Therefore, in this second step S3, etching gas 21 is also prevented from passing through the pores 16 of the SiOCN film 13 and etching the silicon oxide film 12. Figure 4B After this etching, the exhaust and purging gas supply in step S4 is performed again.

[0047] When steps S1 to S4 are performed sequentially in a loop, for example, after the second step S4 described above, this loop is repeated a predetermined number of times. By controlling this repetition, the etching of the polysilicon film 14 and the formation of the protective film 24 (protection of the silicon oxide film 12) are performed in combination, while preventing the etching of the silicon oxide film 12, the polysilicon film 14 is etched downwards. Then, for example, when the polysilicon film 14 is completely etched, the silicon oxide film 15 is exposed on the surface of the wafer W. Figure 5A ).

[0048] Then, amine gas and HF gas 22 are supplied to wafer W to etch the silicon oxide film 15. Figure 5B (Step S5). Similar to the silicon oxide film 15, the silicon oxide film 12 and SiOCN film 13 are also etchable, but are prevented from etching by the protective film 24 formed on the upper surfaces of the silicon oxide film 12 and SiOCN film 13. Furthermore, the passage of HF gas 22 through the hole 16 is also prevented by the protective film 24 formed on the hole 16. In other words, etching of the sidewalls of the silicon oxide film 15 is prevented.

[0049] When the supply of amine gas and HF gas 22 is completed for a specified time, exposing the lower film 11 on the underside of the silicon oxide film 15, the supply of these gases is stopped. Figure 6A Then, the wafer W is heated (step S6). Through this heating, the amine 23 that has entered the aperture 16 to form the protective film 24 vaporizes and is removed from the wafer W. Figure 6B ).

[0050] Furthermore, while it has been described that amine 23 remains on the surface of wafer W during etching in the series of processes described above, it is also possible that it reacts with etching gas 21 and HF gas 22 to become a reaction product and remain on the surface of wafer W. In this case, if a reaction product is generated, heating is performed in step S6 to remove it. That is, the heating in step S6 is for removing amine 23 and / or the reaction product; specifically, for example, wafer W is heated to 100°C to 400°C. Figure 7 The surface portion of wafer W after step S6 is shown.

[0051] According to the processing described in the above embodiment, when etching the polysilicon film 14, amine gas is supplied to form a protective film 24 on the silicon oxide film 12 and the SiOCN film 13. While protecting the silicon oxide film 12 and the SiOCN film 13, etching is performed using etching gas 21. After etching the polysilicon film 14, amine gas and HF gas 22 are supplied to etch the silicon oxide film 15. In this way, the effect of the amine gas relative to the oxygen-containing silicon film switches depending on the presence or absence of HF gas 22, thereby preventing the etching of the silicon oxide film 12 and the SiOCN film 13, while enabling the etching of the silicon oxide film 15. In addition, in addition to the upper surfaces of the silicon oxide film 12 and the SiOCN film 13, a protective film 24 is also formed in the holes 16 of the SiOCN film 13, thus preventing the etching gas 21 from etching the sidewalls of the silicon oxide film 12 through the holes 16. That is, even when adjacent to the film with holes 16, etching of the silicon oxide film 12 can be prevented.

[0052] Furthermore, it is known that when etching the aforementioned silicon oxide film, HF gas and NH3 gas are used, in which case NH3 gas is used to activate the HF gas. However, as described above, in this embodiment, amine gas used to form the protective film 24 is used instead of NH3 gas to enhance the activity of the HF gas during the etching of the silicon oxide film 15. That is, compared to the above-described method of using etching gas 21 and amine gas when etching the polycrystalline silicon film 14, and using HF gas and NH3 gas when etching the silicon oxide film 15, the process in this embodiment does not require the supply of NH3 gas. Therefore, it is not necessary to configure the apparatus to provide the NH3 gas supply system, thus reducing the manufacturing cost and operating cost of the apparatus.

[0053] Furthermore, according to this embodiment, the time from the end of etching the polysilicon film 14 to the start of etching the silicon oxide film 15 can be shortened. More specifically, since amine gas is used for both the etching of the polysilicon film 14 (steps S1-S4) and the etching of the silicon oxide film 15 (step S5), it is easy to configure the apparatus to perform steps S1-S4 and S5 in the same processing container. In other words, it is easy to configure the apparatus so that there is no wafer W transport time between processing containers. That is, as described above, although the silicon oxide film 15 can be etched using HF gas and NH3 gas, by using amine gas instead of NH3 gas, it is easy to perform the process in the same processing container. By performing the process in the same processing container, unnecessary transport is eliminated, and therefore, according to this embodiment, the throughput can be improved.

[0054] Furthermore, in steps S1 to S4 above, the exhaust flow rate of the processing container can be fixed, or the exhaust flow rate in steps S2 and S4, which are used to remove unwanted gases from the processing container, can be larger than the exhaust flow rate in steps S1 and S3, so as to remove the gas more reliably. Alternatively, it can be configured so that no purging gas is supplied in steps S2 and S4, and unwanted gases are removed only by exhaust.

[0055] The example shows that steps S1 to S4 are repeated three or more times during the etching of the polycrystalline silicon film 14, but the number of repetitions is not limited to the example above; for example, it could be twice. Alternatively, steps S1 to S4 can be performed only once without repetition. Furthermore, steps S2 and S4, used to remove unwanted gases, can be omitted. Specifically, the timing of supplying amine gas, etching gas 21 for silicon, and HF gas 22 to the processing container can be set as shown. Figure 8As shown, the other gas is supplied without interval from the end of the supply of one of the gases, amine gas and etching gas 21. In addition, in the case where steps S2 and S4 are omitted, steps S1 and S3 for supplying amine gas and etching gas 21 respectively are not limited to being repeated, and can be set to be performed only once.

[0056] Furthermore, the amine gas and etching gas 21 are not limited to being supplied sequentially. That is, the supply of one gas is not limited to starting after the supply of the other gas has ended; it can also be as follows: Figure 9 As shown, amine gas and etching gas 21 are supplied to wafer W simultaneously for processing. With amine gas and etching gas 21 supplied simultaneously, the formation of protective film 24 and etching of polysilicon film 14 are performed in parallel.

[0057] Furthermore, it is shown that during etching of the silicon oxide film 15, Figure 8 , Figure 9 In the processes described in Figures 2 to 6, amine gas and HF gas 22 are supplied simultaneously, but not limited to this simultaneous supply. For example, it is also possible to... Figure 10 Amine gas and HF gas 22 are supplied alternately and sequentially as shown. When supplying amine gas and HF gas 22 alternately in this manner, they can also be supplied at intervals, with a purge gas supplied between the supply of amine gas and HF gas. Furthermore, in this… Figure 10 In the example shown, during the etching of the polycrystalline silicon film 14, the following is illustrated: Figure 8 The example shown also alternates between supplying amine gas and etching gas 21, but as mentioned above, the supply of amine gas and etching gas 21 is not limited to alternating in this manner.

[0058] in addition, Figure 1 The film structure of the wafer W shown is an example. The Si (silicon) film to be etched is not limited to polycrystalline silicon film 14; for example, it can also be an amorphous silicon (α-Si) film. Furthermore, the porous film is not limited to SiOCN film 13; porous films such as SiCO film and SiCOH film can be formed instead of SiOCN film 13. As shown in the evaluation test, amines readily adsorb onto oxygen-containing silicon films (films containing silicon and oxygen), therefore, it is preferable that the porous film contains oxygen to adsorb amines. Here, "containing oxygen" does not mean containing oxygen as an impurity, but rather containing oxygen as a component of the film. Furthermore, an example of using HF gas 22 as the first etching gas for etching the silicon oxide film 15 is shown, but even if a fluorine-containing gas (a gas with F as a constituent element) other than HF gas 22 is used, the same effect as HF gas can be expected; for example, CF4 (carbon tetrafluoride) gas, CHF3 (trifluoromethane) gas, etc., can be used.

[0059] Additionally, in step S6 described above, the wafer W is heated to remove the reaction products of amine 23 with etching gas 21 and HF gas 22, and / or amine 23, from the silicon oxide film 12 and SiOCN film 13. However, if the adsorption of amine 23 and / or reaction products on the surfaces of the silicon oxide film 12 and SiOCN film 13 (including the surfaces of the holes) does not cause problems in subsequent processing or the practical use of the product, then it can remain as is. Therefore, the heat treatment in step S6 is not necessarily necessary.

[0060] Furthermore, the amine 23 constituting the amine gas is not limited to butylamine. Specific examples include hexylamine, dipropylamine, n-octylamine, tert-butylamine, decylamine, dodecylamine, dicyclohexylamine, tetradecylamine, etc. The boiling points of these amines are all within the range of 100°C to 400°C. Therefore, it is preferable to heat the wafer W to 100°C to 400°C to remove the amine in a vaporized state in step S6 of the above embodiment.

[0061] Next, refer to Figure 11 The substrate processing apparatus 3 for performing the series of processes described above will be described using a top view. The substrate processing apparatus 3 includes a loading / unloading section 31 for loading and unloading wafer W, two loading interlock chambers 41 adjacent to the loading / unloading section 31, two heat treatment modules 40 adjacent to each of the two loading interlock chambers 41, and two etching modules 5 adjacent to each of the two heat treatment modules 40. This substrate processing apparatus 3 is configured to perform the aforementioned steps S1 to S5 within the same processing container.

[0062] The loading / unloading section 31 includes an atmospheric pressure transport chamber 33 equipped with a first substrate transport mechanism 32 and set to atmospheric pressure, and a carrier stage 35 for holding and storing a wafer W, located on the side of the atmospheric pressure transport chamber 33. Figure 36 shows a locator chamber adjacent to the atmospheric pressure transport chamber 33, which is provided to optically determine the eccentricity of the wafer W by rotating it, thereby aligning the wafer W relative to the first substrate transport mechanism 32. The first substrate transport mechanism 32 transports the wafer W between the carrier 34 on the carrier stage 35, the locator chamber 36, and the loading interlock chamber 41.

[0063] Each loading interlock chamber 41 is equipped with a second substrate transport mechanism 42 having a multi-joint arm structure. This second substrate transport mechanism 42 transports the wafer W between the loading interlock chamber 41, the heat treatment module 40, and the etching module 5. The processing container constituting the heat treatment module 40 and the processing container constituting the etching module 5 are set to a vacuum atmosphere. The loading interlock chamber 41 switches between an atmospheric pressure atmosphere and a vacuum atmosphere to enable the transfer of the wafer W between the atmospheric pressure transport chamber 33 and these vacuum atmosphere processing containers.

[0064] In the figure, 43 represents a freely opening and closing gate valve, which is respectively located between the atmospheric pressure transport chamber 33 and the loading interlock chamber 41, between the loading interlock chamber 41 and the heat treatment module 40, and between the heat treatment module 40 and the etching module 5. The heat treatment module 40 includes the aforementioned processing container, an exhaust mechanism for venting air from the processing container to create a vacuum atmosphere, and a mounting stage disposed within the processing container and capable of heating the placed wafer W. The heat treatment module 40 is configured to perform the aforementioned step S6.

[0065] Next, refer to Figure 12 The etching module 5 will be described using a longitudinal sectional side view. This etching module 5 performs steps S1 to S5 on the wafer W, and for example, includes a circular processing container 51. That is, steps S1 to S5 are performed within the same processing container. The processing container 51 is an airtight vacuum container, and a circular stage 61 for placing the wafer W on a horizontal surface (upper surface) is provided on the lower side of the processing container 51. Figure 62 shows a stage heater embedded in the stage 61, used to heat the wafer W to a predetermined temperature to perform the aforementioned steps S1 to S5. Figure 63 shows a support pillar that supports the stage 61, which serves as the mounting part, on the bottom surface of the processing container 51. Figure 64 shows a vertical lifting pin that protrudes and retracts relative to the surface of the stage 61 via a lifting mechanism 65, facilitating the transfer of the wafer W between the second substrate transport mechanism 42 and the stage 61. There are three lifting pins 64, but only two are shown in the diagram.

[0066] Figure 66 shows a sidewall heater installed on the sidewall of the processing container 51, used to adjust the atmosphere temperature inside the processing container 51. Additionally, a wafer W transfer port (not shown) that can be opened and closed freely is provided on the sidewall of the processing container 51. Figure 67 shows an exhaust port opening at the bottom of the processing container 51, connected via an exhaust pipe to an exhaust mechanism 68 consisting of a vacuum pump and valves. By adjusting the exhaust flow rate from the exhaust port 67 using the exhaust mechanism 68, the pressure inside the processing container 51 is adjusted.

[0067] A gas spray head 7 is disposed above the mounting platform 61 and on top of the processing container 51, facing the mounting platform 61. The gas spray head 7 includes a spray plate 71, a gas diffusion space 72, and a diffuser plate 73. The spray plate 71 is horizontally disposed to form the lower surface of the gas spray head 7, and has a large number of gas ejection holes 74 dispersedly formed to spray gas onto the mounting platform 61 in a spray pattern. The gas diffusion space 72 is a flat space formed such that its lower side is divided by the spray plate 71 to supply gas to each gas ejection hole 74. The diffuser plate 73 is horizontally disposed to divide the gas diffusion space 72 vertically. 75 in the figure shows a through hole formed in the diffuser plate 73, and a large number of through holes are dispersedly perforated in the diffuser plate 73. 77 in the figure shows a top heater used to adjust the temperature of the gas spray head 7.

[0068] The downstream ends of gas supply pipes 78 and 81 are connected to the upper side of the gas diffusion space 72. The upstream side of gas supply pipe 78 is connected to the supply source 70 of etching gas 21 via a flow adjustment unit 79. The flow adjustment unit 79, which is composed of a valve or a mass flow controller, is used to adjust the flow rate of gas supplied to the downstream side of gas supply pipe 78. In addition, each flow adjustment unit described later is constructed in the same way as the flow adjustment unit 79 and is also used to adjust the flow rate of gas supplied to the downstream side of the pipe on which the flow adjustment unit is provided. Furthermore, the downstream end of gas supply pipe 52 is connected to gas supply pipe 78 at a position downstream of flow adjustment unit 79, and the upstream side of gas supply pipe 52 is connected to the supply source 54 of HF gas 22 via a flow adjustment unit 53. Therefore, the supply of etching gas 21 to gas spray head 7 and the supply of HF gas 22 to gas spray head 7 can be carried out independently.

[0069] The upstream side of the gas supply pipe 81 is connected to a tank 83 storing liquid amine via a flow adjustment section 82. The tank 83 is equipped with a heater to heat the amine inside, causing it to vaporize. The tank 83 is configured to supply vaporized amine (amine gas) to the downstream side of the gas supply pipe 81. Additionally, for example, the gas supply pipe 81 branches upstream of the flow adjustment section 82 to form a gas supply pipe 84. The gas supply pipe 84 is connected to an N2 (nitrogen) supply source 86 via a flow adjustment section 85. Therefore, amine gas and N2 gas can be supplied to the gas spray head 7 independently. Furthermore, a heater (not shown) is provided in the gas supply pipe 81 to prevent the flowing amine gas from liquefying.

[0070] The correspondence between steps S1 to S5 performed in the etching module 5 and the gas supplied from the gas spray head 7 is shown in advance. In step S1, amine gas is supplied from the tank 83 to the gas spray head 7 to supply amine gas into the processing container 51. In steps S2 and S4, N2 gas is supplied from the N2 gas supply source 86 to the gas spray head 7 to supply N2 gas into the processing container 51 as a purge gas. In step S3, the gas supply from the tank 83 and the N2 gas supply source 86 is stopped, and etching gas 21 is supplied from the supply source 70 to the gas spray head 7 to supply the etching gas 21 into the processing container 51. In step S5, the amine gas is supplied from the tank 83 to the gas spray head 7, and the HF gas 22 is supplied from the supply source 54 to the gas spray head 7 to supply these gases into the processing container 51.

[0071] During each of the aforementioned steps S1 to S5, the temperature of the wafer W in the etching module 5 is set to, for example, 60°C to 120°C. Heating the wafer W to a relatively high temperature in this way prevents ammonium fluorosilicate (AFS), a byproduct generated during the etching of the silicon oxide film 15, from remaining on the wafer W. Furthermore, the pressure inside the processing container 51 is set to, for example, 1.33 Pa (10 mTorr) to 1333 Pa (10 Torr) during the steps S1 to S5.

[0072] In addition, such as Figure 11 , Figure 12 As shown, the substrate processing apparatus 3 includes a control unit 30, which functions as a computer. This control unit 30 includes a program, memory, and a CPU. Commands (steps) are programmed into the program to perform the aforementioned processing and transport of the wafer W. This program is stored on a computer storage medium, such as an optical disc, hard disk, optical disc drive, or DVD, and installed in the control unit 30. The control unit 30 outputs control signals to each part of the substrate processing apparatus 3 through this program to control the operation of each part. Specifically, the control signals control the operation of the etching module 5, the heat treatment module 40, the first substrate transport mechanism 32, the second substrate transport mechanism 42, and the positioner chamber 36. The operation of the etching module 5 includes adjusting the output of each heater, cutting off the gas supply from the gas spray head 7, adjusting the exhaust flow rate using the exhaust mechanism 68, and raising and lowering the lifting pin 64 using the lifting mechanism 65. The control unit 30 and the etching module 5 constitute the etching apparatus.

[0073] The transport path of the wafer W in the substrate processing apparatus 3 will be described. For example, via... Figure 1As explained, the carrier 34 containing the wafer W with each film formed is placed on the carrier stage 35. Then, the wafer W is transported in the order of atmospheric pressure transport chamber 33 → positioner chamber 36 → atmospheric pressure transport chamber 33 → loading interlock chamber 41, and then transported to the etching module 5 via the heat treatment module 40. Then, the polysilicon film 14 and the silicon oxide film 15 are etched as described in steps S1 to S5. Next, the wafer W is transported to the heat treatment module 40 for the processing in step S6. Then, the wafer W is returned to the carrier 34 by transporting it in the order of loading interlock chamber 41 → atmospheric pressure transport chamber 33.

[0074] In the substrate processing apparatus 3, as described above, the etching of the polysilicon film 14 (steps S1 to S4) and the etching of the silicon oxide film 15 (step S5) are performed in the same processing container 51, thereby achieving a high throughput. However, these etching processes can also be performed in different processing containers. Furthermore, the supply of amine gas and etching gas 21 in steps S1 to S4 are not limited to being performed in the same processing container 51. That is, these gas-supply processes can be performed in different processing containers, but by performing them in the same processing container, the time required for transporting the wafer W can be eliminated, which is therefore preferable.

[0075] in addition, Figure 13 A silicon oxide film 10 formed on the surface of wafer W is shown. Amine gas (in...) is supplied to this silicon oxide film 10. Figure 13 (Represented by dashed lines) to form a protective film 24. Furthermore, HF gas 22 is supplied at a desired time (in...) Figure 13 (Solid lines are used to indicate this). For example, with the protective film 24 formed as shown, an etching gas is supplied to the wafer W to etch the film (not shown) formed on the surface of the wafer W, excluding the silicon oxide film 10. Then, HF gas 22 is supplied to the wafer W to remove the protective film 24 and further remove the surface of the silicon oxide film 10. Therefore, in the processing example described by Figures 2 to 6, although the silicon oxide film where the protective film 24 is formed and the silicon oxide film being etched are located in different positions, it is possible to etch the same silicon oxide film and to protect it from etching by the etching gas due to the formation of the protective film.

[0076] Alternatively, regarding the silicon oxide film 10, after etching a portion of the silicon oxide film 10 by first supplying HF gas 22, amine gas is supplied to form a protective film 24. This protects the silicon oxide film 10 from etching by the etching gas (an etching gas that etches films other than the silicon oxide film 10 formed on the surface of the wafer W) supplied to the wafer W after the formation of the protective film 24. Therefore, either the formation of the protective film 24 or the etching of the silicon oxide film can be performed first. Alternatively, the etching of the silicon oxide film and the formation of the protective film 24 can be performed multiple times separately. In this way, according to this technology, the protection and etching of the silicon oxide film can be easily controlled by switching the gas supplied to the wafer W, which is advantageous. Furthermore, the silicon oxide films 10, 12, and 15 described above can be films formed by heating Si in an oxygen atmosphere, or films formed by CVD or ALD.

[0077] As an oxygen-containing silicon film, an example of forming and etching a protective film on a silicon oxide film is shown, but the oxygen-containing silicon film is not limited to a silicon oxide film. For example, the protective film 24 can also be formed and etched on the SiOCN film described above.

[0078] Furthermore, it should be understood that all points in the embodiments disclosed herein are illustrative rather than restrictive. The above embodiments may be omitted, substituted, modified, and / or combined in various ways without departing from the appended claims and their spirit.

[0079] (Evaluation Test)

[0080] Evaluation tests conducted in connection with the technology disclosed herein are described.

[0081] Evaluation Experiment 1

[0082] As an evaluation experiment 1, the adsorption energies of NH3, butylamine, hexylamine, and trimethylamine, which are N (nitrogen) molecules, relative to various Si-containing molecules were measured by simulation. Specifically, the adsorption energies relative to Si (silicon), SiC (silicon carbide), SiN (silicon nitride), SiO2CN (=SiOCN), and SiO (silicon oxide) were measured.

[0083] Figure 14 This is a bar graph showing the results of evaluation experiment 1. The vertical axis of the bar graph represents the adsorption energy (unit: eV), and the lower the adsorption energy, the easier the adsorption. For example... Figure 14As shown, the adsorption energies of various amines among Si, SiC, SiN, SiO₂CN, and SiO are different. Relative to SiN, SiO₂CN, and SiO, the adsorption energies of each amine are negative, indicating that amines adsorb onto these compounds. Especially relative to SiO₂CN and SiO, the adsorption energies are low, making the amines readily adsorbed. This is because the adsorption site of amines is an oxygen atom. On the other hand, relative to Si and SiC, the adsorption energies of each amine are positive, indicating low adsorption capacity.

[0084] According to the results of evaluation test 1, the adsorption properties of various amines differ depending on the type of silicon-containing film. Therefore, as described in the embodiments, it is estimated that such differences in amine adsorption properties can be utilized to protect one type of silicon-containing film while etching the others. Furthermore, from... Figure 14 The bar graph shows that the adsorption energy differences between Si and SiOCN, and between Si and SiO, are particularly large. Therefore, it can be seen that, as illustrated in Figures 2-6, a protective film 24 can be formed on the silicon oxide film 12 and the SiOCN film 13, and the polycrystalline silicon film 14 can be selectively etched. Furthermore, it can be seen that the adsorption energy of amines is low with respect to SiOCN, thus allowing for sufficient sealing of the pores 16 of the SiOCN film 13.

[0085] Evaluation Experiment 2

[0086] As part of evaluation experiment 2, butylamine gas was supplied to substrates with different types of silicon-containing films on their surfaces. Specifically, the gas was supplied to substrates with SiGe film, α-Si film, SiOC film, SiN film, polycrystalline silicon (Poly-Si) film, SiO2 (silicon oxide) film, and SiOCN film as the aforementioned silicon-containing films. Then, the amount of butylamine adsorbed in each film was determined by gas chromatography-mass spectrometry (GC-MS).

[0087] Figure 15 This is a bar graph showing the results of evaluation test 2. (As shown...) Figure 15 As shown, the adsorption capacity of butylamine varies for different silicon-containing films. For polycrystalline silicon films, α-Si films, and SiN films, the adsorption capacity is approximately 0 ng / cm³. 2 The adsorption capacities of SiOC and SiGe films are approximately 0.02 ng / cm³. 2 ~0.03ng / cm 2 The adsorption capacity of the silicon oxide film is approximately 0.10 ng / cm³. 2 The adsorption capacity of the SiOCN film is approximately 0.27 ng / cm³. 2 .

[0088] In this way, the adsorption amount of the amine varies depending on each film. Therefore, based on the results of Evaluation Test 2, similarly to Evaluation Test 1, it can be known that selective etching can be performed using the difference in the adsorption amount. Specifically, it can be known that: regarding the adsorption amount, since the polysilicon film < silicon oxide film < SiOCN film, a protective film 24 can be formed on the silicon oxide film 12 and the SiOCN film 13 as illustrated in FIGS. 2 to 6, and the polysilicon film 14 can be selectively etched. Moreover, it can be known that the pores 16 of the SiOCN film 13 can be sufficiently sealed.

[0089] Explanation of Reference Numerals

[0090] W: wafer; 12: silicon oxide film; 22: HF gas; 23: amine; 24: protective film.

Claims

1. An etching method comprising supplying an etching gas to a substrate to etch a surface, the etching method comprising the following steps: In the protection process, amine gas is supplied to the substrate on which a first silicon film containing oxygen is disposed, so as to form a protective film on the surface of the first silicon film containing oxygen to prevent it from being etched by the etching gas. In the second etching process, a second etching gas, which is one of the etching gases, is supplied to the substrate on which the protective film is formed to etch the etchable film covering the oxygen-containing second silicon film disposed on the substrate. The protective film prevents the oxygen-containing first silicon film from being etched by the second etching gas. as well as In the first etching process, the amine gas and a first etching gas, which is one of the etching gases, are supplied to the substrate to etch the oxygen-containing second silicon film, wherein the first etching gas is a fluorine-containing gas.

2. The etching method according to claim 1, characterized in that, In the substrate, there exists a membrane with a hole between the etched film and the oxygen-containing first silicon film, the hole opening into both the etched film and the oxygen-containing first silicon film. The protective process includes forming a protective film in the hole to block it. The second etching process includes supplying the second etching gas while the pore is blocked by the protective film.

3. The etching method according to claim 2, characterized in that, The membrane with pores is a third type of silicon-containing membrane containing oxygen.

4. The etching method according to claim 2, characterized in that, The membrane with pores is a porous membrane.

5. The etching method according to claim 1, characterized in that, The etched film is a silicon film.

6. The etching method according to claim 1, characterized in that, The oxygen-containing first silicon film and the oxygen-containing second silicon film are silicon oxide films.

7. The etching method according to claim 1, characterized in that, The first etching gas is hydrogen fluoride gas.

8. An etching apparatus for supplying etching gas to a substrate to etch a surface, the etching apparatus comprising: Handling containers; A stage for holding the substrate on which a first silicon film containing oxygen is disposed; A first gas supply unit is used to supply amine gas to the substrate on which a first silicon film containing oxygen is disposed, so as to form a protective film on the surface of the first silicon film containing oxygen to prevent it from being etched by the etching gas. The third gas supply unit is used to supply a second etching gas, which is one of the etching gases, to the substrate on which the protective film is formed, so as to etch the etchable film disposed on the substrate and covered with an oxygen-containing second silicon film, wherein the protective film prevents the oxygen-containing first silicon film from being etched by the second etching gas. A second gas supply unit is used to supply the amine gas and a first etching gas, which is one of the etching gases, to the substrate to etch the oxygen-containing second silicon film, wherein the first etching gas is a fluorine-containing gas; and A control unit outputs control signals to the first gas supply unit, the second gas supply unit, and the third gas supply unit to perform the etching method according to any one of claims 1 to 7.

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