Substrate processing method and substrate processing apparatus

Abstract

Provided is a technique for forming a desired etching shape by removing an etching residual portion of a germanium-containing silicon film. The etching method comprises the following steps: supplying etching gas for germanium-containing silicon to a substrate on which a silicon film and a germanium-containing silicon film are formed to etch the germanium-containing silicon film, and then supplying purge gas containing first processing gas and second processing gas to the substrate to purge the etching gas from the substrate, the first processing gas contains fluorine, and the second processing gas contains at least one of ammonia and amine, and removes an etching residual portion of the germanium-containing silicon film.

Description

Technical Field

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

[0002] When manufacturing semiconductor devices, one of a silicon (Si) film and a silicon (SiGe) film containing germanium formed on the surface of a semiconductor wafer (hereinafter referred to as a wafer) as a substrate is sometimes selectively etched. For example, Patent Document 1 describes a technique for reducing the concentration of byproduct gas to suppress damage to Si when selectively etching SiGe using a fluorine-containing gas.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 7113711 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The present disclosure provides a technology for removing an etching residue of a germanium-containing silicon film to form a desired etching shape.

[0008] Solutions for solving problems

[0009] The present invention discloses a substrate processing method, comprising the following steps:

[0010] supplying an etching gas for silicon containing germanium to a substrate on which a silicon film and a silicon film containing germanium are formed to etch the silicon film containing germanium; and

[0011] Next, a purge gas including a first process gas containing fluorine and a second process gas containing at least one of ammonia and amine is supplied to the substrate to purge the etching gas from the substrate and remove the etching residue of the germanium-containing silicon film.

[0012] Effects of the Invention

[0013] According to the present disclosure, it is possible to remove the etching residue of the germanium-containing silicon film to form a desired etching shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a longitudinal sectional side view showing an example of a structure to which the substrate processing method of the present disclosure is applied.

[0015] Figure 2 It is a first enlarged longitudinal cross-sectional view of the structure.

[0016] Figure 3 is a second enlarged longitudinal cross-sectional view of the structure.

[0017] Figure 4 It is a third enlarged longitudinal cross-sectional view of the structure.

[0018] Figure 5 It is an explanatory diagram showing an example of the process flow of the substrate processing method.

[0019] Figure 6 This is a diagram for explaining the concept of adjusting the processing conditions when removing the etching residue.

[0020] Figure 7 is a plan view showing an example of a substrate processing system for implementing the substrate processing method.

[0021] Figure 8 The figure is a longitudinal sectional side view showing an example of a processing module provided in the substrate processing system.

[0022] Fig. 9 These are enlarged photographs showing experimental results related to Examples and Comparative Examples. DETAILED DESCRIPTION

[0023] <Examples of structures formed by substrate processing of the present disclosure>

[0024] First, refer to Figure 1 An example of the structure 71 formed on the wafer W by the substrate processing method of the present disclosure will be described. Figure 1 : is a longitudinal sectional side view of the structure 71. A multilayer film in which SiGe films 75 and Si films 74 are alternately stacked is formed on a wafer W. In the multilayer film, the Si films 74 are arranged so as to sandwich the SiGe films 75 from the upper surface side and the lower surface side.

[0025] The multilayer film has an opening 72 formed in the longitudinal direction (the direction intersecting the plurality of SiGe films 75 and Si films 74). Figure 2 As shown in the enlarged longitudinal cross-sectional view of FIG. 7 , the side end surfaces of the SiGe film 75 and the Si film 74 in the multilayer film are exposed toward the opening 72. When the etching gas for etching SiGe is supplied through the opening, the etching removal progresses from the side end surface of the SiGe film 75, and a lateral hole ( Figure 3 ).

[0026] In this way, the partial regions of the plurality of SiGe films 75 whose side end faces are exposed toward the opening 72 are respectively etched away. Figure 1 As shown, a plurality of recessed portions 73 that are open toward the opening 72 and are arranged at different height positions in the longitudinal direction can be formed.

[0027] like Figure 3As shown in the enlarged longitudinal cross-sectional view of FIG. 7 , when viewed from the opening of the recess 73, the side walls along the length direction of the recess 73 where the etching process progresses (the walls on the upper surface side and the lower surface side in the case of the lateral hole) are formed by the Si film 74. In addition, the bottom wall of the recess 73 corresponding to the position where the etching process stops is composed of the SiGe film 75.

[0028] Here, in Figure 1 In the structure 71 shown, the shape of the front end of each recess 73 is preferably rectangular, depending on the request for subsequent processing to be performed on the wafer W. On the other hand, it is understood that the front end of the recess 73 formed by the above method may have a rounded shape ( Figure 3 ).

[0029] The following mechanism is conceivable as to why the front end of the recess 73 is rounded. Figure 1 In the multilayer film of the structure 71, sometimes, after a plurality of Si films 74 and SiGe films 75 are alternately stacked, an annealing process is performed by heating the wafer W. It is conceivable that in the multilayer film that has been annealed, Si atoms diffuse from the Si film 74 toward the SiGe film 75, thereby forming a mixed layer 751 ( Figure 2 ). In addition, the mixed layer 751 is not limited to being formed by annealing the wafer W, and may also be formed by natural diffusion of Si atoms.

[0030] For example, the SiGe film 75 of this example is formed in such a manner that the concentration of Ge atoms is in the range of 10 to 30 atm%, for example, 25 atm% (in this case, the concentration of Si atoms is about 75 atm%). On the other hand, in the mixed layer 751, the concentration of Ge atoms is reduced to about 5 to 10 atm%. That is, the mixed layer 751 becomes a region where the concentration of Si atoms is increased to about 90 to 95 atm%.

[0031] Here, in the etching process for forming the recessed portion 73, an etching gas suitable for etching and removing the SiGe film 75 having the above-mentioned composition ratio (Si:Ge=75:25) is selected as the etching gas used for etching the SiGe film 75. However, the etching gas selected for the purpose of etching and removing the SiGe film 75 may sometimes have a slow etching rate in the mixed layer 751 having a high concentration of Si atoms.

[0032] In this case, when comparing along the film thickness direction of the SiGe film 75, the etching rate is high in the central region where the concentration of Si atoms is low, while the etching rate is low in the mixed layer 751 where the concentration of Si atoms is high. It is conceivable that the result of the difference in etching rate depending on the position in the SiGe film 75 is as follows: Figure 3As shown in FIG. 1 , the front end of the recess 73 formed by etching is rounded. Since the etching rate is relatively low, the SiGe (at the boundary between the side wall and the bottom wall of the recess 73) Figure 3 ) is equivalent to the etching residue 752 of the present disclosure.

[0033] It is also conceivable that if the etching residue 752 is formed due to a high concentration of Si atoms, an etching gas suitable for the composition of the mixed layer 751 may be used to perform a separate process of etching and removing the etching residue 752. Figure 3 As shown, the etching residue 752 remains in an extremely small area compared to the entire structure 71. It is not realistic to set up an etching device for forming the recess 73 or to ensure time for transporting the wafer W to the etching device and performing the etching process in order to remove such a small etching residue 752. In addition, the etching gas that can etch the etching residue 752 with a Si atom concentration of about 90 to 95 atm% may also damage the Si film 74 constituting the side wall of the recess 73 depending on the processing conditions.

[0034] Therefore, in the substrate processing method disclosed in the present invention, after the SiGe film 75 is etched to form the recess 73, the etching residue 752 is removed by utilizing the timing of purging the etching gas. Figure 5 , Figure 6 The following will describe the details of the substrate processing method of the present disclosure that can form the recessed portion 73 having a shape close to a rectangular shape at the tip portion.

[0035] <Substrate processing method>

[0036] like Figure 5 As shown, first, SiGe etching gas is supplied to the wafer W having a multilayer film formed thereon. As a result, the etching gas enters Figure 2 The etching process of the SiGe film 75 progresses from the end side exposed toward the opening 72 of the multilayer film shown (process P1: step of etching the SiGe film 75). As for the etching gas for SiGe, at least one selected from the group consisting of F2 gas, ClF3 gas, SF6 gas, and IF7 gas can be cited. In the following example, the case of using F2 gas and ClF3 gas as the etching gas for SiGe, and using, for example, Ar (argon) gas and N2 (nitrogen) gas as the carrier gas is described.

[0037] Regarding the supply flow rate of each gas, it can be exemplified that the F2 gas is set to a flow rate within the range of 1 to 100 sccm, the ClF3 gas is set to a flow rate within the range of 0.1 to 2.0 sccm, the N2 gas is set to a flow rate within the range of 50 to 200 sccm, and the Ar gas is set to a flow rate within the range of 10 to 100 sccm. In addition, for example, the pressure during the etching process is set to a value within the range of 1.3 to 40 Pa (10 to 300 mTorr), and the temperature of the wafer W is set to a value within the range of -50 to 150°C. In addition, regarding the time of the etching process, in the case of forming a recess 73 with a depth of about several nm, 50 seconds within the range of 5 to 120 seconds can be exemplified. The etching gas can etch and remove the SiGe film 75 even without being activated by plasma or the like.

[0038] The etching process described above forms Figure 3 The concave portion 73 shown in the figure, on the other hand, has a rounded front end. Therefore, in the present disclosure, after the etching of the SiGe film 75 is completed, a purge gas including a processing gas for etching and removing the etching residue 752 is supplied when the etching gas is purged ( Figure 5 Process P2: Process of purging etching gas and removing etching residue 752). In addition, as a reference, when etching and removing etching residue 752 is not performed, a case where N2 gas is supplied at 100 sccm and Ar gas is supplied at 100 sccm as purge gas can be exemplified.

[0039] As the processing gas included in the purge gas, a first processing gas and a second processing gas are used, the first processing gas contains fluorine, and the second processing gas contains at least one of ammonia and amine. As the first processing gas containing fluorine, at least one selected from the group consisting of F2 gas, ClF3 gas, SF6 gas, and IF7 gas can be cited.

[0040] The second process gas may be NH3 gas, amine gas, or a mixed gas thereof. When the second process gas contains amine gas, the amine may be selected from the group consisting of trimethylamine and butylamine.

[0041] In the following example, a case where F2 gas is used as the first process gas and NH3 gas is used as the second process gas is described.

[0042] Here, a mixed gas of F2 gas and NH3 gas can also be used as the etching gas for Si ( Figure 6Therefore, the processing conditions are adjusted so that the gas can etch away the SiGe containing Ge atoms at a concentration of 5 to 10 atm%, that is, the etching residue 752, and purge the etching gas used in the etching process of the SiGe film 75 ( Figure 6 solid line).

[0043] As a first adjustment, Figure 5 During the process P2, the process is performed under lower pressure conditions than during the process P1. Through this pressure adjustment, the etching gas supplied during the process P1 can be discharged from the wafer W and the supply of high-concentration processing gas can be avoided to suppress damage to the Si film 74. After the wafer W is etched in the processing container 41 by the processing module 4 described later, the set value of the pressure change mechanism of the processing container 41 is set to a lower pressure when purging is performed. However, since the mixed gas of the F2 gas and NH3 gas mentioned above is supplied to the processing container 41 as described above, the actual pressure in the processing container 41 is a value in the range of 0.0013 to 66.6 Pa (0.1 to 500 mTorr).

[0044] As a second adjustment, the supply ratio of the process gas is adjusted so that the ratio of the F2 gas (first process gas) to the NH3 gas (second process gas) contained in the purge gas is within a range of 15:1 to 5:1. Figure 6 In the case of the Si etching gas indicated by the dashed line in FIG. 1 , the supply ratio is adjusted so that the ratio of F2 gas to NH3 gas is about 100: 1. Therefore, by reducing the supply ratio of F2 gas which has a large influence on Si etching, damage to the Si film 74 is suppressed.

[0045] Regarding the supply flow rate of each gas, the flow rate of F2 gas is set to 50 to 1000 sccm, and the flow rate of NH3 gas is set to 1 to 100 sccm. In addition, the temperature of the wafer W is within the range of -50 to 150°C, and is not changed, and the processing gas is not activated by plasma or the like.

[0046] As the third adjustment, the process is carried out in a shorter time than that of process P1. Figure 5 The following example can be given: for example, as described above, the etching process of the SiGe film 75 is performed for a time in the range of 5 to 120 seconds, while on the other hand, the purging performed while supplying the mixed gas of F2 gas and NH3 gas is set to 10 seconds in the range of 1 to 50 seconds. By completing the purging using the mixed gas of F2 gas and NH3 gas in a shorter time than the etching process of the SiGe film 75, it is possible to suppress damage to the Si film 74 and remove the tiny etching residue 752.

[0047] In the above, various adjustments are made when supplying the first processing gas (F2 gas in the above example) and the second processing gas (NH3 gas in the above example) as purge gas. Through this process, the etching residue 752 of the mixed layer 751 can be removed, and the desired etching shape can be formed so that the front end of the recess 73 is close to a rectangle. Here, "making the front end of the recess 73 close to a rectangle" means that the area on the central side of the bottom wall of the recess 73 and the mixed layer 751 are made flatter by removing the etching residue 752.

[0048] In addition, in process P2, it is not necessary to implement all the above-mentioned adjustments. As long as the etching gas supplied in process P1 can be purged and the etching residue 752 can be removed to make the front end of the recess 73 close to a rectangle, only a part of the adjustments can be implemented. In addition, process P2 can also be performed under conditions other than all the adjustment examples.

[0049] <Substrate processing system>

[0050] Next, refer to Figure 7 , Figure 8 To illustrate the implementation Figure 1 to Figure 6 An embodiment of a substrate processing apparatus for substrate processing is described. The substrate processing system 2 includes: a loading and unloading unit 21 for loading and unloading wafers W; two load lock chambers 31, which are arranged adjacent to the loading and unloading unit 21; two thermal processing modules 30, which are arranged adjacent to the two load lock chambers 31; and two processing modules 4, which are respectively arranged adjacent to the two thermal processing modules 30. The processing module 4 is equivalent to the substrate processing apparatus of the present disclosure.

[0051] The loading and unloading section 21 includes a normal pressure transfer chamber 23 provided with a first substrate transfer mechanism 22 and set to a normal pressure atmosphere, and a carrier mounting table 25 provided at a side of the normal pressure transfer chamber 23 for mounting a carrier 24 for accommodating a wafer W. Figure 7 Reference numeral 26 in the figure denotes an alignment chamber adjacent to the atmospheric transfer chamber 23. In the alignment chamber 26, the wafer W is rotated and the eccentricity is optically obtained to align the wafer W with respect to the first substrate transfer mechanism 22. The first substrate transfer mechanism 22 transfers the wafer W between the carrier 24 on the carrier mounting table 25, the alignment chamber 26, and the load lock chamber 31.

[0052] In each load lock chamber 31, for example, a second substrate transfer mechanism 32 having a multi-joint arm structure is provided, and the second substrate transfer mechanism 32 transfers the wafer W between the load lock chamber 31, the heat treatment module 30, and the processing module 4. The processing container constituting the processing module 4 is set to a vacuum atmosphere, and the load lock chamber 31 is switched between a normal pressure atmosphere and a vacuum atmosphere, so that the wafer W can be exchanged between the processing containers in these vacuum atmospheres and the normal pressure transfer chamber 23.

[0053] exist Figure 7 In the figure, reference numeral 33 indicates a gate valve that can be opened and closed freely. Gate valves 33 are respectively provided between the atmospheric transfer 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 treatment module 4. The heat treatment module 30 is configured to include the above-mentioned processing container, an exhaust mechanism for exhausting the processing container to form a vacuum atmosphere, and a stage that is provided in the processing container and can heat the wafer W placed therein, etc., and can perform a process of heating the wafer W to sublime the reaction product.

[0054] Reference Figure 8 The processing module 4 of the substrate processing apparatus of the present disclosure is described with reference to the longitudinal sectional side view of FIG. The processing module 4 performs the above-mentioned processing P1 and P2. Figure 8 In the figure, reference numeral 41 denotes a processing container constituting the processing module 4. In addition, reference numeral 42 in the figure denotes a transfer port for wafers W opened in the side wall of the processing container 41. The transfer port 44 is opened and closed by the gate valve 33 described above. A stage 51 for placing wafers W is provided in the processing container 41, and a lifting pin (not shown) is provided on the stage 51. The wafers W are exchanged between the second substrate transfer mechanism 32 and the stage 51 described above by means of the lifting pin.

[0055] A temperature adjustment unit 52 is embedded in the stage 51, and the wafer W placed on the stage 51 is heated to the above-mentioned temperature. The temperature adjustment unit 52 is configured as, for example, a flow path that forms a part of a circulation path for circulating a fluid for temperature adjustment such as water, and adjusts the temperature of the wafer W by exchanging heat with the fluid. However, the temperature adjustment unit 52 is not limited to such a flow path for the fluid, and may be configured as, for example, a heater for resistance heating.

[0056] In addition, one end of the exhaust pipe 53 opens in the processing container 41, and the other end of the exhaust pipe 53 is connected to an exhaust mechanism 55, such as a vacuum pump, via a valve 54 as a pressure changing mechanism. The pressure in the processing container 41 is set to the pressure in the above-mentioned range by adjusting the opening of the valve 54 to perform the processing.

[0057] A gas shower head 56 as a processing gas supply mechanism is provided on the upper side of the processing container 41 so as to face the stage 51. The gas shower head 56 is connected to the downstream side of the gas supply paths 611 to 615, and the upstream side of each gas supply path 611 to 615 is connected to the gas supply sources 631 to 635 via the flow adjustment section 62. Each flow adjustment section 62 includes a valve and a mass flow controller. For the gas supplied from the gas supply sources 631 to 635, the gas is supplied to and cut off from the downstream side by opening and closing the valve included in the corresponding flow adjustment section 62.

[0058] F2 gas, ClF3 gas, NH3 gas, Ar gas, and N2 gas are respectively supplied from gas supply sources 631, 632, 633, 634, and 635. Therefore, these F2 gas, ClF3 gas, NH3 gas, Ar gas, and N2 gas can be respectively supplied from the gas shower head 56 into the processing container 41. Ar gas and N2 gas are supplied into the processing container 41 as carrier gas together with F2 gas and ClF3 gas as etching gas. In addition, F2 gas and NH3 gas are supplied into the processing container 41 as purge gas.

[0059] In addition, if Figure 7 As shown, the substrate processing system 2 includes a control unit 20 as a computer, and the control unit 20 includes a program, a memory, and a CPU. In the program, commands (various steps) are programmed to perform the processing of the wafer W and the conveyance of the wafer W as described above. The program is stored in, for example, an optical disk, a hard disk, a magneto-optical disk, a DVD, a non-volatile memory, etc., and is installed in the control unit 20. The control unit 20 outputs control signals to each part of the substrate processing system 2 through the program to control 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 conveying mechanism 22, the operation of the second substrate conveying mechanism 32, and the operation of the alignment chamber 26 are controlled by control signals. As the operation of the above-mentioned processing module 4, for example, each operation includes heating the fluid supplied to the stage 51, supplying and cutting off each gas from the gas shower head 56, and adjusting the exhaust flow rate using the valve 54.

[0060] <Operation of the Substrate Processing System>

[0061] The processing operation of the wafer W in the substrate processing system 2 is described. Figure 1 The carrier 24 of the wafer W having the multilayer film and the opening 72 formed thereon as described in the above is placed on the carrier mounting table 25. The wafer W is then transferred in the order of the atmospheric pressure transfer chamber 23 → alignment chamber 26 → atmospheric pressure transfer chamber 23 → load lock chamber 31, and is then transferred to the processing module 4 via the heat treatment module 30. Figure 5In the process P1, a part of the SiGe film 75 is etched away to form the recess 73. Figure 5 In the process P2, the etching gas for SiGe is purged, and the etching residue 752 is removed by a mixed gas of F2 gas and NH3 gas as the purge gas. Through these processes, the shape of the front end of the recess 73 can be made close to a rectangle.

[0062] Then, the wafer W is transferred from the processing module 4 in the order of the thermal processing module 30 , the load lock chamber 31 , and the atmospheric pressure transfer chamber 23 , and is returned to the carrier 24 .

[0063] <Transformation>

[0064] Here, the object to which the substrate processing method of the present disclosure is applied is not limited to the substrate having Figure 1 The wafer W of the structure 71 shown. For example, the substrate processing method disclosed in the present disclosure can also be applied to a wafer W in which a region where Si is formed is arranged between a region where SiGe is formed when viewed from the upper surface side. In this case, an etching gas for SiGe is supplied to the surface of the wafer W to etch SiGe, thereby forming a recess extending toward the lower side of the wafer W. Then, a purge gas containing a first processing gas containing fluorine and a second processing gas containing at least one of ammonia and amine is used to remove the etching residue 752 so that the front end of the recess is close to a rectangle, which is the same as the embodiment described above.

[0065] In addition, the substrate processing method disclosed herein is not limited to the case where the concave portion is formed. For example, the technology disclosed herein can also be applied when a SiGe film formed on the upper surface of a Si film is patterned. In this case, after a patterned resist film and a sacrificial film are further formed on the upper surface of the SiGe film, an etching gas for SiGe is supplied to etch the SiGe. Then, a purge gas including a first processing gas and a second processing gas can be used to remove the layer of the etching residue remaining on the bottom surface of the patterned SiGe film.

[0066] In addition, it is not necessary to complete the purging by a purge gas containing a first process gas containing fluorine and a second process gas containing at least one of ammonia and amine. It is also possible to further supply another gas (for example, an inactive gas such as N2 gas, Ar gas, etc.) after the above-mentioned purging to continue the purging. On the contrary, the etching residue 752 can be removed by using a purge gas containing a first process gas and a second process gas after first purging with an inactive gas.

[0067] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The embodiments described above may be omitted, replaced, or modified in various ways without departing from the appended claims and the gist thereof.

[0068] Example

[0069] (experiment)

[0070] After supplying SiGe etching gas to wafer W having a multilayer film of SiGe film 75 and Si film 74 to form recess 73 , the type of purge gas supplied to wafer W was changed to check the shape of the front end of recess 73 .

[0071] A. Experimental conditions

[0072] (Example) A concave portion 73 with a depth of 40 nm was formed under the conditions set in the aforementioned range. Then, the pressure setting value was changed to the aforementioned first adjusted pressure, and a purge was performed by supplying F2 gas at a flow rate of 600 sccm and NH3 gas at a flow rate of 40 sccm for 10 seconds. The longitudinal cross-sectional shape of the wafer W subjected to these processes was observed by an electron microscope.

[0073] (Comparative Example) The same process as in (Example) was performed except that the purge gas was supplied at a flow rate of 200 sccm for N 2 gas and 200 sccm for Ar gas.

[0074] B. Experimental Results

[0075] exist Fig. 9 (a) shows an enlarged photograph of (embodiment), Fig. 9 (b) shows an enlarged photograph of (Comparative Example). According to these photographs, in (Example), the residual effect of the etching residue 752 was not observed, and the concave portion 73 with a rectangular front end was obtained. On the other hand, in (Comparative Example), the shape of the front end of the concave portion 73 was rounded. It can be considered that when using Figure 3 The mixed layer 751 described above is formed under the influence of the etching residue 752 .

[0076] The above experimental results confirm that the front end of the recess 73 can be made close to a rectangular shape by supplying a purge gas including F2 gas (first process gas) and NH3 gas (second process gas) after the recess 73 is formed by etching the SiGe film 75.

[0077] Description of Reference Numerals

[0078] W: wafer; 71: structure; 73: recess; 74: Si film; 75: SiGe film; 752: etching residue.

Claims

1. A substrate processing method, comprising the following steps: supplying an etching gas for silicon containing germanium to a substrate on which a silicon film and a silicon film containing germanium are formed to etch the silicon film containing germanium; and Next, a purge gas including a first process gas containing fluorine and a second process gas containing at least one of ammonia and amine is supplied to the substrate to purge the etching gas from the substrate and remove the etching residue of the germanium-containing silicon film.

2. The substrate processing method according to claim 1, wherein: The etching residue is formed in a region where the etching rate of the etching gas for the germanium-containing silicon decreases as the silicon concentration increases due to diffusion of silicon from the silicon film side to the germanium-containing silicon film side.

3. The substrate processing method according to claim 1, wherein: A multilayer film in which the silicon film is stacked with the germanium-containing silicon film interposed therebetween is formed on the substrate, In the step of etching the germanium-containing silicon film, the germanium-containing silicon film is etched from the end side of the multilayer film to form a recess having a side wall of the silicon film and a bottom wall of the germanium-containing silicon film. In the step of removing the etching residue, the etching residue remaining at the boundary between the side wall and the bottom wall of the recessed portion is removed, so that the cross-sectional shape of the recessed portion is made close to a rectangle.

4. The substrate processing method according to claim 1, wherein: The step of removing the etching residue is performed under a lower pressure condition than the step of etching the germanium-containing silicon film.

5. The substrate processing method according to claim 1, wherein: The ratio of the first process gas to the second process gas contained in the purge gas is in a range of 15:1 to 5:

1.

6. The substrate processing method according to claim 1, wherein: The step of removing the etching residue is performed in a shorter time than the step of etching the germanium-containing silicon film.

7. The substrate processing method according to claim 1, wherein: The etching gas for germanium-containing silicon is at least one selected from the group consisting of F2 gas, ClF3 gas, SF6 gas, and IF7 gas.

8. The substrate processing method according to claim 1, wherein: The first process gas is at least one selected from the group consisting of F2 gas, ClF3 gas, SF6 gas, and IF7 gas.

9. The substrate processing method according to claim 1, wherein: When the second process gas contains an amine gas, the amine is an amine selected from the group consisting of trimethylamine and butylamine.

10. A substrate processing device comprising: a processing container for storing a substrate on which a silicon film and a silicon film containing germanium are formed; an etching gas supply mechanism for supplying etching gas for silicon containing germanium into the processing container; a purge gas supply mechanism for supplying a purge gas including a first process gas and a second process gas into the process container, wherein the first process gas contains fluorine and the second process gas contains at least one of ammonia and amine; and A control unit outputs a control signal, wherein the control signal is used to implement the following steps: supplying the etching gas into the processing container to etch the germanium-containing silicon film; and then supplying the purge gas to purge the etching gas from the processing container and remove the etching residue of the germanium-containing silicon film.

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