Substrate processing method and substrate processing device

Abstract

A substrate processing method according to the present disclosure comprises a first step for supplying a gas of a silylation agent to a substrate comprising a silicon-containing film and a second step for supplying a hydrogen fluoride gas to the substrate subjected to the first step, wherein: the first step is a protective film formation step for forming a protective film for preventing the silicon-containing film from reacting to a gas around the substrate; and the second step is a protective film removal step for removing the protective film after the gas has been removed from around the substrate.

Description

Substrate processing method and substrate processing apparatus

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

[0002] In manufacturing a semiconductor device, a silicon oxide film formed on a surface of a semiconductor wafer (hereinafter referred to as a wafer) that serves as a substrate is sometimes etched. Patent Document 1 discloses that in etching in which a silicon oxide film is modified and a reaction product generated by the modification is removed by heating, HF gas and NH ３ There is described a technology including a first modification step using 3 gas and a second modification step using HF gas. Note that Patent Document 2 describes a technology of etching a silicon film while protecting the silicon oxide film by forming a protective film made of an amine thereon. Patent Document 3 discloses that, in an apparatus that performs plasma processing on a substrate, a protective film, which is a water-repellent silicon-containing film, is formed on each member in a processing chamber by generating plasma of TMSDMA gas, thereby preventing adhesion of moisture to each member during maintenance of the apparatus.

[0003] Japanese Patent No. 6812284 Japanese Unexamined Patent Publication No. 2021-174938 Japanese Patent No. 7357182

[0004] The present disclosure provides a technology capable of suppressing occurrence of defects caused by processing performed on a substrate or conveyance of the substrate by using a silylating agent gas and hydrogen fluoride gas.

[0005] The substrate processing method of the present disclosure comprises: a first step of supplying a silylating agent gas to a substrate provided with a silicon-containing film; and a second step of supplying hydrogen fluoride gas to the substrate on which the first step has been performed, wherein the first step is a protective film forming step of forming a protective film for preventing reaction of the silicon-containing film with gas surrounding the substrate, and the second step is a protective film removing step of removing the protective film after the gas is removed from the surroundings of the substrate. Another substrate processing method of the present disclosure comprises: a step of supplying a silylating agent gas to a substrate provided with a silicon-containing film in order to remove halogen from the silicon-containing film of the substrate; and a step of supplying hydrogen fluoride gas to the substrate in order to remove, from the surface of the silicon-containing film, carbon constituting silyl groups supplied from the silylating agent to the silicon-containing film.

[0006] The present disclosure, by using a silylating agent gas and hydrogen fluoride gas, can suppress the occurrence of defects caused by processing performed on a substrate and conveyance of the substrate.

[0007] It is a vertical cross-sectional side view showing a substrate before processing in the first embodiment of the present disclosure. It is an explanatory diagram showing a silylation reaction in the first embodiment. It is a process diagram showing processing of a substrate in the first embodiment. It is a process diagram showing processing of a substrate in the first embodiment. It is a plan view showing an example of a substrate processing apparatus that performs the processing of the first embodiment. It is a vertical cross-sectional side view of a processing module provided in the substrate processing apparatus. It is a process diagram showing processing according to a modified example of the first embodiment. It is a vertical cross-sectional side view of a module for performing processing according to the modified example. It is a process diagram showing processing of a substrate in the second embodiment. It is a process diagram showing processing of a substrate in the second embodiment. It is a process diagram showing processing of a substrate in the second embodiment. It is an explanatory diagram showing a substitution reaction in the second embodiment. It is a graph diagram showing results of an evaluation test. It is a graph diagram showing results of an evaluation test.

[0008] Processing that is the first embodiment of the substrate processing method of the present disclosure will be described. FIG. 1 shows a wafer W in a state before processing is performed. As shown in FIG. 1, on the wafer W, SiO, each of which is a silicon-containing film, ２ (silicon oxide) film 11 and SiN (silicon nitride) film 12 are formed. These SiO２ Both the film 11 and the SiN film 12 are exposed on the surface of the wafer W and are exposed to the gas supplied to the wafer W.

[0009] SiO ２ The film 11 may be formed by any method, such as a thermal oxide film formed by heating Si (silicon) in an oxygen atmosphere, or an oxide film formed by CVD using a film forming raw material such as TEOS (Tetra ethoxy silane). In the present embodiment, HF (hydrogen fluoride) gas as an etching gas and NH which is a basic gas are supplied to the wafer W ３ (ammonia) gas is supplied, and SiO ２ of the film 11 and the SiN film 12, SiO ２ film 11 is selectively etched. This etching is performed before all of the SiO ２ film 11 is etched before it is stopped. That is, the processing is performed such that a part of the SiO ２ film 11 remains on the wafer W.

[0010] The HF gas and NH which are the above etching gases ３ Regarding the etching resistance to gas, SiO ２ the film 11 is relatively high, and the SiN film 12 is relatively low. Therefore, originally, HF gas and NH ３ by supplying the gas to the wafer W, SiO ２ selective etching of the film 11 can be performed. However, in practice, supplying this etching gas may also etch the SiN film 12 relatively significantly. This is because the surface layer of the SiN film 12 is oxidized by the treatment before this etching, so that the surface layer becomes SiO ２ it is considered to be due to having properties similar to those of the film 11.

[0011] In order to suppress etching of the SiN film 12, in this first embodiment, a silylation agent gas is supplied to the wafer W before supplying an etching gas to the wafer W. This silylation agent gas is a compound gas containing silicon (Si) and an alkyl group, and a more specific example is trimethylsilyldimethylamine (N-(Trimethylsilyl)dimethylamine):TMSMDMA) gas. It is presumed that the supply of this silylation agent gas causes the chemical reaction shown in Figure 2 to proceed on the surface layer of the SiN film 12, thereby forming a protective film 13.

[0012] As shown in Figure 2, in the surface layer of the SiN film 12, some of the Si-N bonds are broken, and hydroxyl groups (-OH) are bonded to Si, forming Si-OH bonds. Therefore, since the surface layer of the SiN film 12 contains oxygen (O), as described above, the surface layer is SiO ２ It is thought to possess properties similar to those of film 11.

[0013] In the chemical reaction equation shown in Figure 2, the silylating agent is SiR ３ This is represented as X. R is an alkyl group. As will be described later, the silylation agents used do not necessarily have a structure in which three alkyl groups are bonded to Si, but for convenience, Figure 2 shows it as if three alkyl groups are bonded to Si. When the silylation agent gas is supplied to the SiN film 12, a chemical reaction proceeds and the hydrogen (H) of the hydroxyl group (-OH) bonded to Si is converted into a silyl group (-Si(R)). ３ ) is substituted with a protective film 13. The compound formed by the bonding of X, which was the atomic group constituting the silylation agent, and H, which was removed from the hydroxyl group, is in gaseous form and is removed by exhaust from the processing vessel in which the wafer W is stored. Note that in Figure 2, when the silylation agent is TMSMDMA, R is a methyl group (-CH ３ ), silyl group (-Si(R) ３ ) is a trimethylsilyl (TMS) group, and X is an amino group (-N(CH) ３ ) ２ ) is a compound HX produced by silylation, and dimethylamine (NH(CH) ３ ) ２ )

[0014] The protective film 13 thus formed is a modified surface layer of the SiN film 13, and the thickness of the SiN film 12 including the protective film 13 hardly changes before and after its formation. Since the OH groups of the SiN film 12 containing oxygen on its surface are hydrophilic and the silyl groups are hydrophobic, the formation of the protective film 13 makes the surface layer of the SiN film 12 hydrophobic.

[0015] By the way, not only SiN film 12, but SiO ２ The film 11 will also be silylated on its surface by coming into contact with the silylating agent gas. However, SiO ２ Even when the film 11 is silylated in this way, HF gas and NH ３ It has been confirmed that it is etched by gas, SiO ２ It is presumed that the effect of the silylation agent on film 12 is small. As described above, of the films formed by silylation, only the film formed on SiN film 12 functions as a protective film, so in the figures such as Figure 3 shown later, the protective film 13 is SiO ２ The diagram shows that the coating is formed only on the SiN film 12, of the two films, film 11 and SiN film 12.

[0016] As described above, in the first embodiment, the silylation agent gas is supplied to the wafer W, and SiO ２ After silylation of film 11 and SiN film 12, SiO ２ Selective etching of the film 11 is performed. However, if these films remain silylated after etching (i.e., if silyl groups remain attached to these films), there is a risk that malfunctions may occur in the processing performed on the wafer W after etching, or that the silyl groups remaining in the wafer W as impurities may impair the reliability of the devices manufactured from the wafer W.

[0017] By heating the wafer W to a relatively high temperature, for example, around 600°C, it is possible to remove silyl groups from each film. However, performing such high-temperature heat treatment may complicate the structure of the heat treatment apparatus, making it difficult to handle, and it may not be feasible from the standpoint of preventing damage to each film formed on the wafer W. Therefore, in the first embodiment, HF gas is supplied to the wafer W after the etching described above. The results of the evaluation tests described later show that supplying HF gas in this way allows for the removal of silyl groups. In the case of the SiN film 12, the protective film 13 is removed.

[0018] Referring to the process diagrams in Figures 3 and 4, a series of processes performed on the wafer W in the first embodiment will be described. In this example, TMSDMA gas is used as the silylation agent gas. Each gas treatment performed on the wafer W is carried out with the wafer W stored in a processing container whose interior is evacuated.

[0019] First, TMSDMA gas is supplied to the wafer W as explained in Figure 1 (step S1). This allows SiO to be released. ２ The surface layers of film 11 and SiN film 12 are silylated, and TMS groups bond to the oxygen atoms on the surface. This silylation forms a protective film 13 on SiN film 12 (Figure 3(a)). As the reaction proceeds as explained in Figure 2, the protective film 13 is thought to correspond to the oxidized areas on SiN film 12. Therefore, Figure 3(a) shows the protective film 13 being formed over the entire surface of SiN film 12, but it is also possible that the protective film 13 may be formed locally.

[0020] Subsequently, the wafer W is treated with etching gases, HF gas and NH ３ The gas is supplied. The SiN film 12 is protected by the protective film 13, which suppresses the reaction with the etching gas, and SiO ２ Of the film 11 and the SiN film 12, SiO ２ Selective etching of the film 11 is performed (step S2, Figure 3(b)). SiO ２ Once the film 11 has been etched to the desired extent, NH is applied to the wafer W. ３The gas supply was stopped, and as shown in Figure 4(a), HF gas and NH ３ Of the gases, only HF gas is supplied to wafer W, and SiO ２ The TMS groups are removed from film 11 and SiN film 12 (step S3). In other words, after the etching gas is removed from around the wafer W by exhausting the processing container and the SiN film 12 is removed from the environment in which it is etched, the protective film 13 is removed from the SiN film 12.

[0021] The pressure inside the processing vessel in steps S1 to S3 described above is, for example, 5.0 Pa to 40.0 Pa. The temperature of the wafer W in steps S1 to S3 is, for example, 20°C to 120°C. However, since the evaluation test described later shows that the reactions in steps S1 to S3 are performed at 35°C, steps S1 to S3 may be performed with the wafer W at a temperature of 35°C or lower.

[0022] After steps S1 to S3 are performed, the wafer W is heated to a temperature higher than the temperature of the wafer W in steps S1 to S3. This heating sublimes and removes the reaction products that were generated during step S2 and adhered to the surface of the wafer W, thus ending the processing of the wafer W (Figure 4(b)).

[0023] According to the first embodiment described above, SiO ２ When etching the film 11, supplying a silylation agent gas to the wafer W can suppress the occurrence of the problem of etching the SiN film 12. ２ After selectively etching the film 11, silyl groups are removed from each film using HF gas, thereby reducing SiO ２ This makes it possible to suppress problems that may occur in post-etching processes performed on film 11 and SiN film 12 due to silylation. Thus, in the first embodiment, by supplying a silylation agent gas, followed by supplying HF gas to the wafer W, SiO ２ This suppresses the occurrence of problems during selective etching of the film 11 and problems during post-etching processing.

[0024] Furthermore, since the removal of silyl groups using HF gas can be carried out in a relatively low temperature range, as illustrated, it is possible to suppress the complexity of the structure of the processing apparatus and damage to each film formed on the wafer W. Also, in this first embodiment, both the silylation agent and HF are supplied to the wafer W as gases. If these compounds were to be supplied as liquids, and if a fine pattern of irregularities is formed on the surface of the wafer W, there is a risk that the surface tension of the liquid may cause the protrusions forming the pattern to collapse. Therefore, the processing in the first embodiment has the advantage of preventing such problems from occurring and preventing a decrease in the yield of semiconductor products manufactured from the wafer W.

[0025] Furthermore, according to this first embodiment, the protective film 13 is removed by a relatively simple process of supplying HF gas. Therefore, this removal process can be carried out quickly, and the processing to be performed on the wafer W after the removal process is completed can be started quickly. Consequently, a decrease in the throughput of the processing apparatus that performs a series of processes on the wafer W is suppressed.

[0026] Next, a substrate processing apparatus 2, which is one embodiment of the substrate processing apparatus that performs the series of processes described in Figures 3 to 4, will be described with reference to the plan view in Figure 5. The substrate processing apparatus 2 is installed in an atmospheric environment and includes an loading / unloading section 21 for loading and unloading wafers W, two load lock chambers 31 provided adjacent to the loading / unloading section 21, two heat treatment modules 30 provided adjacent to each of the two load lock chambers 31, and two processing modules 4 provided adjacent to each of the two heat treatment modules 30. As will be described in detail later, the processing module 4 is a module that performs the processes of steps S1 to S3 described above, and the heat treatment module 30 is a module that performs a heat treatment to sublimate the reaction product after the completion of step S3.

[0027] The loading / unloading section 21 includes an atmospheric pressure transport chamber 23, which is equipped with a first substrate transport mechanism 22 and is maintained at atmospheric pressure, and a carrier mounting table 25 provided on the side of the atmospheric pressure transport chamber 23 on which a carrier 24 for storing wafers W is placed. In the figure, 26 is an aligner adjacent to the atmospheric pressure transport chamber 23, and is provided to rotate the wafer W to optically determine the eccentricity and align the wafer W with respect to the first substrate transport mechanism 22. The first substrate transport mechanism 22 transports the wafer W between the carrier 24 on the carrier mounting table 25, the aligner 26, and the load lock chamber 31.

[0028] Each load lock chamber 31 is provided with a second substrate transport mechanism 32, for example, having a multi-joint arm structure, which transports the wafer W between the load lock chamber 31, the heat treatment module 30, and the processing module 4. The processing containers constituting the heat treatment module 30 and the processing containers constituting the processing module 4 are under a vacuum atmosphere. The load lock chamber 31 can be switched between an atmospheric pressure atmosphere and a vacuum atmosphere so that the wafer W can be transferred between these vacuum-atmosphere processing containers and the atmospheric pressure transport chamber 23. In the figure, 33 is an openable and closable gate valve, which is provided between the atmospheric pressure transport chamber 23 and the load lock chamber 31, between the load lock chamber 31 and the heat treatment module 30, and between the heat treatment module 30 and the processing module 4.

[0029] The processing module 4 will be described with reference to the longitudinal cross-sectional side view in Figure 6. In the figure, 41 is a processing container that constitutes the processing module 4. A wafer W transport port 42 is opened in the side wall of the processing container 41, and this transport port 42 is opened and closed by the gate valve 33 described above. A stage 51 on which the wafer W is placed is provided inside the processing container 41, and this stage 51 is equipped with a lifting pin (not shown) for transferring the wafer W to and from the second substrate transport mechanism 32 described above.

[0030] A temperature control unit 52 is embedded in the stage 51, and the wafer W placed on the stage 51 is brought to the temperature described above. This temperature control unit 52 is configured as a flow path that forms part of a circulation path through which a temperature-controlling fluid, such as water, flows, and the temperature of the wafer W is adjusted by heat exchange with the fluid. However, the temperature control unit 52 is not limited to such a fluid flow path, and may be configured as, for example, a heater for resistance heating.

[0031] Furthermore, one end of an exhaust pipe 53 is open inside the processing container 41, and the other end of the exhaust pipe 53 is connected to an exhaust mechanism 55, which is, for example, a vacuum pump. The exhaust pipe 53 is equipped with a valve 54, which is a pressure changing mechanism, and by adjusting the opening of the valve 54, the pressure inside the processing container 41 is set to the pressure within the range described above and processing is carried out.

[0032] A gas shower head 56 is provided in the upper part of the processing container 41, facing the stage 51. The downstream side of the gas supply passages 61 to 65 is connected to the gas shower head 56, and the upstream side of the gas supply passages 61 to 65 is connected to the gas supply sources 71 to 75, respectively, via flow rate adjustment units 66. Each flow rate adjustment unit 66 is equipped with a valve and a mass flow controller, and the supply of gas from the gas supply sources 71 to 75 is cut off to the downstream side by opening and closing the valve included in the flow rate adjustment unit 66.

[0033] From gas supply sources 71, 72, 73, 74, and 75, silylating agents TMSMDMA gas, HF gas, and NH are supplied. ３ Gas, Ar (argon) gas, N ２ (Nitrogen) gas is supplied to each of the gases, and these gases are supplied to the processing container 41 via the gas showerhead 56. Ar gas, N ２The gas is used as a carrier gas. TMSDMA is a liquid at room temperature, and the gas supply source 71 vaporizes the liquid TMSDMA and supplies it to the processing container 41. Specifically, the gas supply source 71 includes, for example, a container that houses and heats the TMSDMA, and a mechanism that supplies carrier gas into the container. The TMSDMA gas vaporized by the supply of carrier gas is supplied to the processing container 41 together with the carrier gas. The gas supply source 71, the gas supply passage 61, and the flow rate adjustment unit 66 interposed in the gas supply passage 61 constitute the first gas supply section. The gas supply source 72, the gas supply passage 62, and the flow rate adjustment unit 66 interposed in the gas supply passage 62 constitute the second gas supply section.

[0034] Next, the heat treatment module 30 will be described. The heat treatment module 30 uses TMSMDMA gas, HF gas, and NH ３ The heat treatment module 30 is configured similarly to the processing module 4, except that gas supply sources 71-73 and gas supply paths 61-63 are not provided because no gas is supplied to the wafer W. In the heat treatment module 30, for example, an inert gas is supplied into the processing container 41, and the wafer W is heated in a vacuum atmosphere by a temperature control unit 52 provided on the stage 51 to remove the reaction products generated during etching in step S2. Therefore, the temperature control unit 52 in the heat treatment module 30 heats the wafer W placed on the stage 51 to a higher temperature than the temperature control unit 52 in the processing module 4. Specifically, for example, in the heat treatment module 30, the wafer W is heated to a temperature of 100°C or higher.

[0035] As shown in Figure 5, the substrate processing apparatus 2 is equipped with a control unit 20, which is a computer. This control unit 20 includes a program, memory, and a CPU. The program incorporates instructions (each step) to perform the processing and transport of the wafer W as described above. This program is stored on a storage medium, such as a compact disk, hard disk, magneto-optical disk, DVD, etc., and installed in the control unit 20. The control unit 20 outputs control signals to each part of the substrate processing apparatus 2 using this program, thereby controlling the operation of each part. Specifically, the operation of the processing module 4, the operation of the heat treatment module 30, the operation of the first substrate transport mechanism 22, the operation of the second substrate transport mechanism 32, and the operation of the aligner 26 are controlled by the control signals. The operation of the processing module 4 controlled by the above control signals includes, for example, the temperature of the fluid supplied to the stage 51, the supply and cut-off of each gas from the gas shower head 56 by the flow rate adjustment unit 66, the adjustment of the flow rate of each gas supplied into the processing container 41, and the adjustment of the exhaust flow rate by the valve 54.

[0036] The transport path for wafers W in the substrate processing apparatus 2 will now be explained. As explained in Figure 1, a carrier 24 containing wafers W on which each film has been formed is placed on a carrier mounting table 25 by a carrier transport mechanism. This carrier transport mechanism is, for example, an OHT (Overhead Hoist Transport) provided in the factory where the substrate processing apparatus 2 is installed, and is not shown in the figure. The wafers W removed from the carrier 24 are then transported in the following order: atmospheric pressure transport chamber 23 → aligner 26 → atmospheric pressure transport chamber 23 → load lock chamber 31, and then transported to the processing module 4 via the heat treatment module 30.

[0037] Then, in the processing module 4, step S1 is performed by supplying TMSDMA gas as shown in Figure 3(a) to the wafer W, and HF gas and NH as shown in Figure 3(b) ３Step S2, which involves supplying gas, and step S3, which involves supplying HF gas as shown in Figure 4(a), are performed in order. After that, the wafer W is transported to the heat treatment module 30 for heat treatment, and then transported in the order of load lock chamber 31 → atmospheric pressure transport chamber 23 to return to carrier 24. The carrier 24 to which the wafer W has returned is then transported by the carrier transport mechanism described above to other substrate processing equipment so that the wafer W can undergo further processing.

[0038] Note that the basic gas contained in the etching gas is NH ３ Not limited to the use of gas, the NH ３ Instead of gas, various amine compound gases such as trimethylamine, dimethylamine, dimethylethylamine, diethylamine, triethylamine, monotertiarybutylamine, pyrrolidine, and pyridine can be used. Furthermore, as other specific examples of amine compounds, various amine gases can be used, such as compounds in which some or all of the C-H bonds of the above compounds are replaced by C-F bonds (e.g., 1,1,1-trifluorodimethylamine).

[0039] [Modification of the First Embodiment] In the processing example of the first embodiment shown in Figures 3 and 4, etching gas (HF gas and NH) is applied to the wafer W. ３ While an etching gas atmosphere is formed around the wafer W as the gas is supplied, a protective film 13 is formed by using TMSMDMA gas to protect the silicon-containing SiN film 12 from this gas atmosphere. However, the protective film 13 is not limited to protecting the silicon-containing film from the etching gas in this way. A specific example will be explained with reference to the process diagram in Figure 7.

[0040] In a semiconductor manufacturing plant, substrate processing devices 2A and 2B are provided, similar to the substrate processing device 2 described above, except for the type of gas that can be supplied to the wafer W by the processing module 4. The process shown in Figure 7 includes the process of transporting the wafer W stored in the carrier 24 from the substrate processing device 2A to the substrate processing device 2B. During this transport between devices, the wafer W is exposed to the atmosphere. A protective film 13 is formed to protect the SiN film 12 from the oxidizing effect of the atmosphere.

[0041] To explain the wafer W transport and processing step by step, a predetermined type of processing gas is supplied to the wafer W in the processing module 4 of the substrate processing apparatus 2A, thereby performing processing such as etching on the SiN film 12. Subsequently, TMSMDMA gas is supplied to the wafer W in the processing module 4, and a protective film 13 is formed on the SiN film 12 (Figure 7(a)). After that, the wafer W is placed in the carrier 24, and the carrier 24 is transported to the substrate processing apparatus 2B by the carrier transport mechanism described above. As described above, the wafer W is exposed to the atmosphere during this transport, but oxidation of the surface of the SiN film 12 by the atmosphere is suppressed because it is covered with the protective film 13 (Figure 7(b)).

[0042] Then, when the carrier 24 is transported to the substrate processing apparatus 2B, the wafer W is transported from the substrate processing apparatus 2B toward the processing module 4. Since the load lock chamber 31 of the substrate processing apparatus 2B is in a vacuum state, the atmosphere is removed from around the wafer W as it is transported toward the processing module 4. After the protective film 13 is removed by supplying HF gas to the wafer W in the processing container 41 of the processing module 4, which is also in a vacuum state (Figure 7(c)), processing such as forming a predetermined film 14 by supplying a film-forming gas is performed on the SiN film 12 (Figure 7(d)).

[0043] As shown in the example in Figure 7, the protective film 13 can be formed as a film that suppresses the reaction of the silicon-containing film with the gas surrounding the wafer W, and the gas surrounding the wafer W is not limited to the etching gas for the silicon-containing film exemplified in Figures 3 and 4. Furthermore, the protective film 13 is not limited to protecting the silicon-containing film from environmental changes around the wafer W caused by processing of the wafer W, such as the supply of etching gas, but may also protect the silicon-containing film from environmental changes around the wafer W caused by the transport of the wafer W.

[0044] Although the protective film 13 has been described as protecting the SiN film 12, the object of protection by the protective film 13 may be a silicon-containing film other than the SiN film. Since silylation can be performed by oxidation of the surface, similar to the SiN film 12, the silicon-containing film may be, for example, Si (silicon). Note that the term "silicon-containing film" refers to a film that contains silicon as a constituent component, not a film that contains it as an impurity. Furthermore, in cases where the substrate itself is made of silicon, such as a silicon substrate, and the silicon-based portion is not covered and is exposed as the surface of the substrate, that exposed portion also falls under the category of a silicon-containing film.

[0045] In addition to TMSDA, other silylation agents for forming the protective film 13 may be dimethylsilyldimethylamine (DMSDMA), hexamethyldisilazane (HMDS), tetramethyldisilazane (TMDS), TMSPyrole (1-Trimethylsilylpyrole), BSTFA (N,O-Bis(trimethylsilyl)trifluoroacetamide), BDMADMS (Bis(dimethylamino)dimethylsilane), etc. For convenience, in Figure 2 the silylation agent is represented as SiR ３ It was represented as X. For TMSMDMA, it was SiR. ３ Although all three R's in X are alkyl groups, the silylation agent is not limited to those in which all three R's are alkyl groups; one or more of the R's may be halogenated alkyl groups. Here, halogenated alkyl groups are those in which one or more hydrogen atoms of an alkyl group are replaced by halogen atoms. In the case of DMSDMA, which is given as an example of a silylation agent, one of the three R's will be represented as H (hydrogen atom). Thus, the silylation agent may be a compound in which some of the three R's are H.

[0046] [Second Embodiment] Next, a processing example of the second embodiment will be described. This processing example involves removing fluorine, a halogen, from a silicon-containing film on the surface of a wafer W, and uses a silylation agent gas and HF gas. In this example, the silicon-containing film is SiO ２ The film 11 is made of SiO ２ The membrane 11 is made of HF gas and NH ３ After etching with gas, SiO ２ The fluorine remaining on the surface of the film 11 is removed. Furthermore, as in the first embodiment, TMSMDMA gas is used as the silylation agent gas.

[0047] The processing in the second embodiment is carried out using a substrate processing apparatus 2C that is configured in general the same way as the substrate processing apparatus 2 described in the first embodiment. The difference between this substrate processing apparatus 2C and the substrate processing apparatus 2 is that it is equipped with a heat treatment module 3A instead of a heat treatment module 30. This heat treatment module 3A can supply a different type of gas than the heat treatment module 30 of the substrate processing apparatus 2. The differences between the heat treatment module 3A and the heat treatment module 30 will be explained using the longitudinal cross-sectional side view of Figure 8.

[0048] The heat treatment module 3A, like the treatment module 4 described in the first embodiment, is provided with a gas supply passage 61 and a gas supply source 71 for supplying TMSMDMA gas into the treatment container 41, and a gas supply passage 62 and a gas supply source 72 for supplying HF gas into the treatment container 41. Therefore, in the heat treatment module 3A, the inert gas (N) supplied from the gas supply sources 74 and 75 is also provided. ２ TMSM DMA gas and HF gas can be supplied to the wafer W using gas or Ar gas as carrier gases. With this configuration, the processing temperature of the wafer W by the temperature control unit 52 is higher, and NH ３ Except for the absence of a gas supply source 73 and a gas supply passage 63 for supplying gas, the heat treatment module 3A has the same configuration as the treatment module 4 described in the first embodiment.

[0049] The following will be explained with reference to Figures 9 to 11, which are process diagrams for the wafer W, and Figure 12, which is an explanatory diagram of the reactions that are presumed to occur on the surface of the wafer W during this process. Figure 9(a) shows the SiO of the wafer W before processing. ２ The film 11 is shown. First, in the processing module 4 of the substrate processing apparatus 2C, HF gas and NH are applied to the wafer W. ３ Gas is supplied, SiO ２ The film 11 is etched (step S11, Figure 9(b)). Once the desired amount has been etched, HF gas and NH ３ Stop the gas supply to terminate the etching. As shown in Figures 9(c) and 12(a), the SiO after etching ２ The surface of the film 11 is the SiO ２ The fluorine atoms 81 that made up the HF gas remain because they are bonded to the Si atoms that make up the film 11.

[0050] Subsequently, the wafer W is transported to the heat treatment module 3A and heated to a higher temperature than during etching in step S11, for example, to a temperature of 100°C or higher, as in the first embodiment. Then, TMSDMA gas is supplied to the wafer W (Figure 10(a), step S12). This TMSDMA gas decomposes into trimethylsilane gas and dimethylamine gas, and as shown in Figure 12(b), the methyl groups constituting trimethylsilane and SiO ２ A substitution reaction occurs between the fluorine atom 81 bonded to the Si atom in the film 11. Through this substitution reaction, trimethylsilane is changed to dimethylfluorosilane, and the gaseous dimethylfluorosilane is removed by the exhaust gas in the processing container 41, so that the fluorine atom 81 becomes SiO ２ It is removed from the film 11. On the other hand, as shown in Figures 10(b) and 12(c), the methyl group 82 is SiO ２ On the surface of the film 11, the SiO ２ It remains bonded to the Si that constitutes the film 11.

[0051] Next, HF gas is supplied to the wafer W (Figure 11(a), step S13). As shown in Figure 12(d), hydrogen and SiO are the components of HF. ２A substitution reaction occurs between the methyl group 82 bonded to the Si atom in the film 11. As a result of this substitution reaction, as shown in Figures 11(b) and 12(e), SiO ２ The methyl group 82 is removed from the film 11. That is, the silylating agent is removed from SiO ２ The carbon derived from the silyl group supplied to the film 11 is SiO ２ It is removed from the surface of the film 11. Due to the action of HF, the methyl group 82 is converted into gaseous methane fluoride and removed by the exhaust gas in the processing container 41.

[0052] As described above, according to the second embodiment, SiO ２ By removing the fluorine atoms 81 and the methyl groups 82 that were donated during the removal of the fluorine atoms 81 from the surface of the film 11, these fluorine atoms 81 and methyl groups 82 are removed from the SiO ２ This suppresses the impact on post-etching processing of the film 11. Note that steps S12 and S13, which remove fluorine atoms 81 and methyl groups 82 by substitution reaction, are not limited to being performed at the relatively high temperature of the wafer W as described above. Since evaluation tests described later have shown that steps S12 and S13 can be performed even when the wafer W temperature is 35°C, steps S12 and S13 may be performed at a temperature of 35°C or lower. Therefore, although steps S11 to S13 are performed using the processing module 4 and the heat treatment module 3A in the above example, steps S11 to S13 may also be performed using only the processing module 4.

[0053] By the way, as shown in Figure 12, fluorine, which is a halogen, bonds to Si atoms, so the silicon-containing film to be treated in this second embodiment is SiO ２The film 11 is not limited to a film, and may be a Si film or the like. The silylation agent gas is not limited to TMSMDMA gas, and various silylation agent gases other than TMSMDMA described in the first embodiment can be used, and the carbon that constituted the silyl group of the silylation agent can be removed from the silicon-containing film by supplying HF gas. Furthermore, although fluorine atoms 81 were given as an example of halogen atoms to be removed from the silicon-containing film, the treatment of this embodiment is not limited to the removal of fluorine atoms 81. The treatment of this embodiment can be used to remove other halogen atoms such as chlorine and bromine from the silicon-containing film.

[0054] Furthermore, the processes performed before and after the treatment of this embodiment (supply of silylating agent gas and subsequent supply of HF gas) are not limited to specific processes. Therefore, in Figures 9 to 11, before the treatment of this embodiment, HF gas and NH ３ Although it is stated that etching is performed using gas, the processing of this embodiment is not limited to wafers W that have undergone such etching. To give a specific example of this embodiment other than those shown in Figures 9 to 11, a known process is to supply a film-forming gas to the surface of a wafer W made of Si or SiGe and epitaxially grow Si or SiGe. In this epitaxial growth, if there are many impurities on the surface of the wafer W, the growth rate will decrease. Therefore, as a pretreatment for epitaxial growth, the above-mentioned TMSMDMA gas and HF gas may be supplied to the wafer W so that halogens, which are one of the impurities, are removed from the Si and SiGe that form the silicon-containing film. Furthermore, the processing of this embodiment may be performed to remove halogens such as fluorine that have become included in the silicon-containing film due to the film-forming process on the wafer W.

[0055] Up to this point, wafers have been used as an example of substrates to be processed, but other substrates to be processed include substrates for manufacturing flat panel displays, substrates for manufacturing exposure masks used in photolithography, and dummy substrates processed for the purpose of testing and setting processing parameters in substrate processing equipment. Furthermore, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, modified, or combined in various ways without departing from the scope and spirit of the attached claims.

[0056] [Evaluation Tests] The evaluation tests conducted in relation to this embodiment will be described below. • Evaluation Test 1 As Evaluation Test 1, the surface was subjected to a thermal oxide film of SiO ２ Multiple substrates on which films were formed were processed using an apparatus having the same configuration as the processing module 4 described in the embodiment, and the surface of each processed substrate was analyzed by XPS (X-ray photoelectron spectroscopy).

[0057] As part of evaluation test 1-1, HF gas and NH were used as etching gases on the substrate. ３ Gas was supplied. As evaluation test 1-2, etching gas was supplied to the substrate under the same conditions as evaluation test 1-1, and then TMSMDMA gas was supplied to the substrate. As evaluation test 1-3, etching gas and TMSMDMA gas were supplied to the substrate in order under the same conditions as evaluation test 1-2, and then HF gas was supplied to the substrate. Therefore, in evaluation test 1-3, each gas was supplied to the substrate in the same order as steps S11 to S13 of the processing example of the second embodiment described in Figures 9 to 11. The processing apparatus used in this evaluation test 1 is configured to process two substrates at once by placing the substrates on stages 51 located on the left and right sides of the processing container 41. Therefore, the processing in evaluation tests 1-1, 1-2, and 1-3 described above was performed on two substrates each.

[0058] In evaluation tests 1-2 and 1-3, the processing conditions during the supply of TMSDMA gas were described in detail as follows: the TMSDMA gas supply time was set to 180 seconds, and the pressure inside the processing container 41 was set to 300 mTorr (40 Pa). Ar gas was supplied along with the TMSDMA gas, and the flow rates of these gases supplied into the processing container 41 were set to TMSDMA gas:Ar gas = 1:1.

[0059] In evaluation test 1-3, the processing conditions for HF gas supply were described in detail as follows: the HF gas supply time was set to 180 seconds, and the pressure inside the processing container 41 was set to 120 mTorr (16 Pa). Ar gas was supplied along with the HF gas, and the flow rates of these gases supplied into the processing container 41 were set to HF gas:Ar gas = 6.4:1. Note that under the processing conditions set in this evaluation test 1-3, SiO ２ It is known that etching of film 11 does not proceed.

[0060] The table below shows the atomic percentage concentrations of each element obtained from each substrate in evaluation tests 1-1 to 1-3. In the table, data obtained from substrates processed on the left side and substrates processed on the right side of the processing container 41 are indicated as (L) and (R), respectively.

[0061] Figure 13 shows the C1s spectra obtained from each substrate in evaluation tests 1-1 to 1-3. In this C1s spectrum, a larger peak around 290 nm indicates a higher carbon content on the substrate surface. Figure 14 shows the F1s spectra obtained from evaluation tests 1-1 to 1-3. In this F1s spectrum, a larger peak around 692 eV (bond energy) indicates a higher fluorine content on the substrate surface. Note that the C1s and F1s spectra in Figures 13 and 14 are representative samples obtained from one of the substrates positioned on the left or right side of the processing container 41.

[0062] Looking at the atomic percentage concentration of carbon in Table 1, it was 0.07% and 0.44% in evaluation test 1-1, 1.12% and 1.14% in evaluation test 1-2, and 0.44% and 0.45% in evaluation test 1-3. Thus, in evaluation test 1-2, the atomic percentage concentration of carbon is higher than in evaluation test 1-1, indicating that silylation of the substrate surface by the TMS group occurred. Furthermore, in evaluation test 1-3, the atomic percentage concentration of carbon is lower than in evaluation test 1-2 and is the same as, or approximately the same as, the value in evaluation test 1-1, suggesting that the TMS group was removed and the silylation was reversed.

[0063] Looking at the C1s spectrum in Figure 13, the peak around 290 nm is roughly the same in evaluation tests 1-1 and 1-3, but higher in evaluation test 1-2 than in evaluation tests 1-1 and 1-3. Therefore, this spectrum, like the results in Table 1, indicates that silylation occurs when TMSMDMA gas is supplied, and silylation is reversed when HF gas is supplied. As described above, the results of this evaluation test 1 indicate that each of the treatments described in the first embodiment can be carried out.

[0064] Furthermore, looking at the atomic percentage concentrations of fluorine in Table 1, the values ​​were 2.75% and 4.07% in evaluation test 1-1, 3.68% and 3% in evaluation test 1-2, and 1.46% and 1.27% in evaluation test 1-3. Thus, the atomic percentage concentrations of fluorine are roughly the same in evaluation tests 1-1 and 1-2, but lower in evaluation test 1-3 than in evaluation tests 1-1 and 1-2. The F1s spectra in Figure 14 show similar results to those in Table 1.

[0065] Therefore, the results of evaluation test 1 indicate that each process described as the second embodiment can be carried out. Furthermore, according to the reaction mechanism described in Figure 12, fluorine is converted to SiO by the supply of TMSMDMA gas. ２Since fluorine is detached from the film, it was expected that the atomic percentage concentration of fluorine atoms in evaluation test 1-2 would be equivalent to that in evaluation test 1-3 and lower than that in evaluation test 1-1. However, as described above, it was equivalent to that in evaluation test 1-1. This is because the TMS group is a relatively bulky functional group, and fluorine is prevented from detaching by interfering with the TMS group, resulting in SiO ２ This is thought to be due to the substance remaining on the surface of the film.

[0066] W wafer 11 SiO ２ (Silicon oxide) film 12 SiN (silicon nitride) film 13 Protective film

Claims

1. A substrate processing method comprising: a first step of supplying a silylation agent gas to a substrate having a silicon-containing film; and a second step of supplying hydrogen fluoride gas to the substrate after the first step, wherein the first step is a protective film formation step of forming a protective film to prevent the silicon-containing film from reacting with a gas surrounding the substrate, and the second step is a protective film removal step of removing the protective film after the gas has been removed from the vicinity of the substrate.

2. The substrate processing method according to claim 1, wherein the gas surrounding the substrate is an etching gas for etching the silicon-containing film.

3. The substrate processing method according to claim 2, wherein the silicon-containing film is a first silicon-containing film, the surface of the substrate to which the etching gas is supplied is exposed and provided with the first silicon-containing film and a second silicon-containing film of a different type from the first silicon-containing film, and the etching step includes selective etching of the second silicon-containing film among the first and second silicon-containing films using the etching gas.

4. The substrate processing method according to claim 3, wherein a processing container for storing the substrate is provided, and the protective film formation step, the etching step, and the protective film removal step are performed in the same processing container.

5. The substrate processing method according to claim 4, wherein the second silicon-containing film is a silicon oxide film, and the etching gas is hydrogen fluoride gas and a basic gas.

6. The substrate processing method according to claim 1, wherein the gas surrounding the substrate is atmospheric air, the protective film formation step is a step of forming the protective film on the substrate in a vacuum atmosphere, and the protective film removal step is a step of removing the protective film from the substrate in a vacuum atmosphere.

7. A substrate processing method comprising: a step of supplying a silylation agent gas to a substrate having a silicon-containing film in order to remove halogens from the silicon-containing film; and a step of supplying hydrogen fluoride gas to the substrate in order to remove carbon constituting silyl groups supplied to the silicon-containing film from the surface of the silicon-containing film from the silylation agent.

8. The substrate processing method according to claim 7, wherein the silicon-containing film is a silicon oxide film.

9. The substrate processing method according to claim 8, comprising the step of etching the silicon oxide film using an etching gas containing hydrogen fluoride before the step of supplying a silylation agent gas to the substrate, wherein the halogen is fluorine.

10. A substrate processing apparatus comprising: a processing container for storing a substrate having a silicon-containing film; a first gas supply unit for supplying a silylation agent gas into the processing container; a second gas supply unit for supplying hydrogen fluoride gas into the processing container; and a control unit that outputs a control signal so that a first step of supplying a silylation agent gas to the substrate in the processing container and a second step of supplying hydrogen fluoride gas to the substrate in the processing container after the first step have been performed, wherein the first step is a protective film formation step of forming a protective film to prevent the silicon-containing film from reacting with a gas surrounding the substrate, and the second step is a protective film removal step of removing the protective film after the gas has been removed from around the substrate.

11. A substrate processing apparatus comprising: a processing container for storing a substrate having a silicon-containing film; a first gas supply unit for supplying a silylation agent gas into the processing container; a second gas supply unit for supplying hydrogen fluoride gas into the processing container; and a control unit that outputs a control signal so that the following steps are carried out: supplying the silylation agent gas to the substrate to remove halogens from the silicon-containing film; and supplying hydrogen fluoride gas to the substrate to remove carbon constituting silyl groups supplied from the silylation agent to the silicon-containing film from the surface of the silicon-containing film.

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