WO2021200240A1

WO2021200240A1 - Etching method and etching device

Info

Publication number: WO2021200240A1
Application number: PCT/JP2021/011215
Authority: WO
Inventors: 信博高橋; 折居　武彦
Original assignee: 東京エレクトロン株式会社
Priority date: 2020-03-30
Filing date: 2021-03-18
Publication date: 2021-10-07
Also published as: JP2021163776A; JP7521230B2; TW202201512A

Abstract

According to the present invention, a silicon film that is formed on the surface of a substrate is etched by supplying a fluorine gas and an amine gas to the substrate.

Description

Etching method and etching equipment

This disclosure relates to an etching method and an etching apparatus.

In constructing a semiconductor device, a Si (silicon) film formed on a semiconductor wafer (hereinafter referred to as a wafer) as a substrate may be etched. For example, Patent Document 1 discloses that a Si film is selectively etched with respect to a SiGe (silicon germanium) film by using _{F 2} (fluorine) gas and NH _{3 gas.}

Japanese Unexamined Patent Publication No. 2016-143781

The present disclosure provides a technique capable of rapidly etching a silicon film formed on a substrate.

The etching method of the present disclosure includes a step of supplying fluorine gas and amine gas to a substrate having a silicon film formed on the surface to etch the silicon film.

According to the present disclosure, the silicon film formed on the substrate can be quickly etched.

It is a longitudinal side view of the surface of the wafer where the etching which concerns on one Embodiment of this disclosure is performed. It is a process drawing explaining the etching. It is a process drawing explaining the etching. It is a process drawing explaining the etching. It is a process drawing explaining the etching. It is a process drawing explaining the etching. It is a process drawing explaining the etching. It is a process drawing explaining the etching. It is a process drawing explaining the etching. It is a process drawing explaining the etching. It is a longitudinal side view of the surface of the wafer after etching treatment. It is a chart figure which shows an example of the gas supply timing at the time of etching. It is a chart figure which shows an example of the gas supply timing at the time of etching. It is a top view of the substrate processing apparatus for performing etching. It is a longitudinal side view of the etching module provided in the substrate processing apparatus. It is a graph which shows the result of the evaluation test. It is a graph which shows the result of the evaluation test. It is a graph which shows the result of the evaluation test.

The process according to one embodiment of the etching method of the present disclosure will be described below. FIG. 1 shows a longitudinal side view of the surface portion of the wafer W on which the processing is performed. In the figure, 11 is a SiGe (silicon germanium) film, and a silicon oxide (SiOx) film 12 is laminated on the upper side of the SiGe film 11. A recess 13 is formed in the laminate of the silicon oxide film 12 and the SiGe film 11, and the polysilicon film 14 is embedded in the recess 13. Further, between the side wall of the polysilicon film 14 and the side wall of the recess 13, the SiOCN film 15, that is, silicon, which surrounds the side of the polysilicon film 14 and is in contact with the side wall of the polysilicon film 14 and the side wall of the recess 13, respectively. A membrane composed of oxygen, nitrogen and carbon is provided. Therefore, the polysilicon film 14, the first film SiOCN film 15, and the second film SiGe film 11 are formed so as to be adjacent to each other in this order when viewed in the lateral direction.

The SiOCN film 15 is an interlayer insulating film called a low-k film, and is a porous film. Therefore, the holes of the SiOCN film 15 are open in the polysilicon film 14 and the SiGe film 11. The polysilicon film 14 is a film to be etched, and the SiGe film 11 is a non-etched film. The silicon oxide film 12 is an etching mask film when etching the polysilicon film 14. To explain the outline of this embodiment, when etching the polysilicon film 14, F ₂ gas and amine gas are supplied to the wafer W. As shown in the evaluation test described later, the etching rate of the polysilicon film can be increased by supplying the _{F 2 gas and the amine gas.}

_{By the way, the F 2} gas, which is an etching gas for the polysilicon film 14, also has an etching property for the SiGe film 11. That is, the polysilicon film 14 and the SiGe film 11 have an etching property with respect to _{the F 2 gas.} It is assumed that the polysilicon film 14 is etched without supplying amine gas. In that case, in the process of etching the polysilicon film 14, the etching gas (F ₂ gas) passes through the pores of the SiOCN film 15 and is supplied to the side wall of the SiGe film 11, and the side wall is etched. It ends up. The amine gas enters the pores of the SiOCN film 15 and is adsorbed on the pore walls to prevent the passage _{of F 2 gas in the pores.} _{As a result, it has a role of preventing the supply of F 2} gas to the side wall of the SiGe film 11 and preventing etching of the side wall.

Further, as will be shown in a later evaluation test, amine has low adsorptivity to the polysilicon film 14, while has high adsorptivity to the SiOCN film 15 and the silicon oxide film 12 which are oxygen-containing silicon films. Therefore, by supplying the amine gas, the surfaces of the SiOCN film 15 and the silicon oxide film 12 are each coated with a protective film of amine, and contact with the etching gas is prevented. Therefore, this protective film prevents etching of the SiOCN film 15 and the silicon oxide film 12. On the other hand, since it is difficult for a protective film to be formed on the surface of the polysilicon film 14, the polysilicon film 14 is etched. Therefore, of the polysilicon film 14, SiOCN film 15, and silicon oxide film 12 exposed on the surface of the wafer W, only the polysilicon film 14 is selectively etched. Since amine has such high adsorptivity to the SiOCN film 15, the performance of preventing the passage _{of F 2 gas by adsorbing the SiOCN film 15 to the pore wall is high.}

Subsequently, with reference to FIGS. 2 to 5, the processing performed on the wafer W will be described step by step. 2 to 5 are schematic views showing how the surface portion of the wafer W described with reference to FIG. 1 changes depending on the processing. In the processing shown in each of these drawings, the wafer W is carried into the processing container. This is performed in a state where the inside of the processing container is exhausted to create a vacuum atmosphere at a predetermined pressure. In the figure, 16 is a hole formed in the SiOCN film 15. Also shows the amine to be supplied to the wafer W as 21, the amine 21, in this embodiment, for example butylamine _(C _{4 H 11} N). Further, F ₂ gas is shown as 22. The protective film formed on the surfaces of the SiOCN film 15 and the silicon oxide film 12 by the amine 21 is shown as 23.

First, amine gas (amine 21 in a gas state) is supplied as amine 21 into the processing container (step S1, FIG. 2A, FIG. 2B). As described above, since the amine 21 is easily adsorbed on the SiOCN film 15, a relatively large amount of amine 21 is adsorbed and stays on the pore wall forming the pore 16, and the pore 16 is sealed. Further, since the amine 21 is easily adsorbed on the silicon oxide film 12 in addition to the SiOCN film 15, a protective film 23 composed of the amine 21 is formed on the upper surfaces of the SiOCN film 15 and the silicon oxide film 12. ..

Subsequently, the supply of the amine gas into the processing container is stopped, and the exhaust gas and, for example _{, the purge gas, which is N 2} (nitrogen) gas, are supplied in the processing container (step S2, FIG. 2C). As a result, the amine gas that does not flow into the pores 16 and does not form the protective film 23 is removed by the air flow of the exhausted purge gas.

_{Subsequently, the F 2} gas 22 is supplied into the processing container, the polysilicon film 14 is etched, and the side wall on the upper side of the SiOCN film 15 is exposed (step S3, FIG. 3A). During the progress of this etching, the amine 21 remains in the pores 16 on the upper side of the SiOCN film 15, and the amine 21 prevents the F ₂ gas 22 from passing through the pores 16 and reaching the SiGe film 11. Will be done. Further, since the protective film 23 is coated, the upper surfaces of the SiOCN film 15 and the silicon oxide film 12 are prevented from being etched by the _{F 2 gas 22.} Therefore, among the silicon oxide film 12, the SiOCN film 15, and the polysilicon film 14, the polysilicon film 14 is selectively etched. _{The F 2} gas 22 is activated by the amine 21 adsorbed on the surface of the wafer W, and the polysilicon film 14 is etched at a relatively high etching rate as described above.

After that, _{the supply of the F 2} gas 22 into the processing container is stopped, the exhaust gas and the purge gas are supplied in the processing container (step S4, FIG. 3B), and the F ₂ gas remaining in the processing container is reached. 22 is removed by riding on the airflow of the purge gas exhausted from the processing container. Subsequently, amine gas is supplied into the processing container. That is, step S1 is executed again. In step S3 above, the polysilicon film 14 is etched to expose the upper side wall of the SiOCN film 15. Therefore, the amine 21 supplied in the second step S1 is supplied to the pore 16 below the pore 16 to which the amine 21 was supplied in the first step S1 in the SiOCN film 15, and is supplied to the pore wall. It is adsorbed (Fig. 4A). A protective film 23 is also formed on the side wall of the exposed SiOCN film 15.

After that, the exhaust gas and the purge gas in the processing container of step S2 are supplied again. _{Subsequently, the F 2} gas 22 is supplied into the processing container in step S3, the polysilicon film 14 is further etched downward, and the exposed region on the side wall of the SiOCN film 15 expands downward. .. Also at this time, the polysilicon film 14 is etched at a high etching rate by _{the F 2} gas 22 activated by the amine 21 adsorbed on the surface of the wafer W.

As described above, in the second step S1, the region where the amine 21 is supplied in the SiOCN film 15 is expanded downward, so that the vicinity of the side wall of the SiOCN film 15 newly exposed by etching the polysilicon film 14 The amine 21 remains in the pore 16 of the. Therefore, also in this second step S3, it is possible to prevent the etching gas from passing through the pores 16 of the SiOCN film 15 and etching the side wall of the SiGe film 11. Further, the protective film 23 formed on the upper surface of each of the SiOCN film 15 and the silicon oxide film 12 and the side surface of the SiOCN film prevents etching of the SiOCN film 15 and the silicon oxide film (FIG. 4B). After this etching, the exhaust gas and purge gas supply in step S4 are performed again.

Assuming that steps S1 to S4 performed in this order are one cycle, the cycle is repeated even after the second step S4 is performed, for example. As a result, the polysilicon film 14 is etched downward while the SiOCN film 15, the SiGe film 11 and the silicon oxide film 12 are prevented from being etched.

Then, for example, when all the polysilicon films 14 are etched and a predetermined number of cycles are completed (FIG. 5A), the wafer W is heated (step S5). By the heating, the amine 21 that has entered the pore 16 and the amine 21 that forms the protective film 23 are vaporized and removed from the wafer W (FIG. 5B).

Although it has been described that the amine 21 stays on the wafer W surface during etching in the above series of treatments, _{it reacts with the F 2} gas 22 to become a reaction product and stays on the wafer W surface. It is also possible that it may remain as a reaction product as such. Then, when such a reaction product is generated, heating is performed so that the reaction product is removed in step S5. That is, the heating in step S5 is heating for removing the amine 21 and / or the reaction product, and specifically, the wafer W is heated to, for example, 100 ° C. to 400 ° C. FIG. 6 shows the surface portion of the wafer W after the execution of step S5. In the recess 17 formed by removing the polysilicon film 14, for example, a gate of a semiconductor device is formed in a later step. NS.

According to the treatment of the above embodiment, since the polysilicon film 14 is etched at a relatively high etching rate, the time required for repeating steps S1 to S4 can be shortened. Therefore, the production efficiency of the semiconductor device can be increased. Further, as described above, the pores 16 of the SiOCN film 15 are sealed by the amine 21, and the protective film 23 made of the amine 21 is formed so as to cover the silicon oxide film 12, so that the silicon oxide film 12 is formed. Etching is prevented. Therefore, etching from the side and etching from above are prevented for the SiGe film 11 located on the side of the SiOCN film 15 and below the silicon oxide film 12. Therefore, it is possible to suppress a decrease in the yield of the semiconductor device.

_{By the way, F 2} gas and NH ₃ gas can be used for etching the polysilicon film as described in Patent Document 1. However, in the treatment of the above embodiment, the amine gas for preventing the etching gas from passing through the pores 16 is used for etching, and the NH ₃ gas may not be supplied to the wafer W. That is, in the treatment of the above embodiment, NH is compared with the case where the amine gas is supplied for the protection of the SiGe film 11 and the etching gas and the NH _{3 gas are supplied for the etching of the polysilicon film 14.} ₃ Gas supply is no longer required. Therefore, it is not necessary to provide _{an NH 3} gas supply system for the device that performs the series of processes shown in FIGS. 2 to 5 above. That is, according to the treatment of the above embodiment, it is possible to prevent an increase in the types of gas required for the treatment and suppress an increase in the manufacturing cost and the operating cost of the treatment apparatus.

Further, the exhaust flow rate of the processing container may be constant in steps S1 to S4 described above, and the exhaust flow rate in steps S2 and S4 for removing unnecessary gas in the processing container is more reliably removed. It may be larger than the exhaust flow rate of steps S1 and S3 so as to be able to do so. Further, in steps S2 and S4, unnecessary gas may be removed only by exhaust gas without supplying purge gas.

Incidentally, an example is a film structure of the wafer W shown in FIG. 1, as the Si film is etched by the supply of F ₂ gas and amine gas is not limited to the polysilicon film 14 may be, for example, amorphous silicon film .. In the above embodiment, the non-etching film is the SiGe film 11, but it may be, for example, a Si film. Further, the non-etching film may be a film other than the silicon-containing film such as these Si film and SiGe film 11. Further, the mask film provided on the SiGe film 11 is not limited to the silicon oxide film 12 as long as it can suppress the etching of the SiGe film 11 from the upper side at the time of etching.

Further, instead of providing the silicon oxide film 12, the upper side of the SiGe film 11 may be covered with the SiOCN film 15. That is, the SiOCN film 15 is provided from the side to the upper side of the SiGe film 11. In that case, when the etching gas is supplied to the wafer W, the amine gas is adsorbed on the SiOCN film 15 covering the upper side of the SiGe film 11, so that the etching gas comes into contact with the SiGe film 11 from the upper side of the SiGe film 11. Is prevented. Further, the porous film is not limited to the SiOCN film 15, and a porous film such as a SiCO film or a SiCOH film may be formed instead of the SiOCN film 15. As shown in the evaluation test, amines are easily adsorbed on the oxygen-containing silicon membrane, so that the porous membrane preferably contains oxygen in order to adsorb the amine. The term "containing oxygen" as used herein does not mean that oxygen is contained as an impurity, but means that oxygen is contained as a component constituting the film.

In the above embodiment, steps S1 to S4 are shown to be repeated three or more times, but the number of repetitions is not limited to the above example, and may be, for example, two times. Further, steps S1 to S4 may be performed only once without repeating. By the way, the above steps S2 and S4 for removing unnecessary gas may be omitted. Specifically, as shown in FIG. 7A, which shows the timing of supplying the amine gas and the F ₂ _{gas into the processing container, respectively, the other of the amine gas and the F 2} gas is not spaced from the end of the supply. Gas may be supplied. May so omit steps S2, S4, amine gas, for F ₂ gas step for supplying respectively S1, S3, not limited to be repeated, may be performed only once.

Further, the amine gas and the F ₂ gas 22 are not limited to being supplied in order. That is, of the amine gas and F ₂ gas 22 is not limited to starting the supply of one gas the other gas after completion of the supply of, as shown in FIG. 7B, at the same time the wafer W the amine gas and F ₂ gas 22 It may be supplied and processed. When the amine gas and the F ₂ gas 22 are supplied at the same time in this way, the polysilicon film 14 is etched by _{the F 2} gas 22 while sealing the pores 16 with the amine gas and forming the protective film 23.

Further, as described above, in step S5, the wafer W is heated so that the reaction product of the _{amine 21 and / or the amine 21 and the F 2 gas is removed from the SiOCN film 15.} However, even if the amine 21 and / or the reaction product remains in the pores 16 of the SiOCN film 15, the amine 21 and the reaction product may remain as long as the dielectric constant of the SiOCN film 15 is not practically problematic. Can be considered. Therefore, the heat treatment in step S5 is not always essential.

Further, the amine 21 constituting the amine gas is not limited to butylamine. Specific examples include hexylamine, dipropylamine, n-octylamine, tertbutylamine, decylamine, dodecylamine, dicyclohexylamine, tetradecylamine and the like. The boiling point of each amine thus exemplified is contained in the range of 100 ° C. to 400 ° C. Therefore, in order to remove the amine as a vaporized state in step S5 of the above embodiment, it is preferable to heat the wafer W to 100 ° C. to 400 ° C. in this way.

Subsequently, the substrate processing apparatus 3 for performing the series of processing described above will be described with reference to the plan view of FIG. The substrate processing device 3 is adjacent to the loading / unloading section 31 for loading / unloading the wafer W, the two load lock chambers 41 provided adjacent to the loading / unloading section 31, and the two load lock chambers 41, respectively. It includes two heat treatment modules 40 provided and two etching modules 5 provided adjacent to each of the two heat treatment modules 40.

The carry-in / out section 31 is provided with a first substrate transport mechanism 32 and a normal pressure transport chamber 33 having a normal pressure atmosphere, and a carrier provided on the side of the normal pressure transport chamber 33 for accommodating the wafer W. It is provided with a carrier mounting table 35 on which the 34 is mounted. Reference numeral 36 denotes an orientation chamber adjacent to the normal pressure transfer chamber 33, which is provided to rotate the wafer W to optically determine the amount of eccentricity and align the wafer W with respect to the first substrate transfer mechanism 32. .. The first substrate transport mechanism 32 transports the wafer W between the carrier 34 on the carrier mounting table 35, the oriental chamber 36, and the load lock chamber 41.

In each load lock chamber 41, for example, a second substrate transfer mechanism 42 having an articulated arm structure is provided, and the second substrate transfer mechanism 42 uses the wafer W as the load lock chamber 41 and the heat treatment module 40. And the etching module 5. The inside of the processing container constituting the heat treatment module 40 and the inside of the processing container forming the etching module 5 have a vacuum atmosphere, and the inside of the load lock chamber 41 includes the inside of the processing container having such a vacuum atmosphere and the normal pressure transfer chamber 33. The normal pressure atmosphere and the vacuum atmosphere are switched so that the wafer W can be transferred between the two.

In the figure, 43 is a gate valve that can be opened and closed, and is between the normal pressure transfer chamber 33 and the load lock chamber 41, between the load lock chamber 41 and the heat treatment module 40, and between the heat treatment module 40 and the etching module 5, respectively. It is provided. Regarding the heat treatment module 40, the above-mentioned processing container, an exhaust mechanism for exhausting the inside of the processing container to form a vacuum atmosphere, a mounting table provided in the processing container and capable of heating the mounted wafer W, and the like are provided. Including, it is configured so that the above-mentioned step S5 can be executed.

Subsequently, the etching module 5 will be described with reference to the longitudinal side view of FIG. The etching module 5 is a module that performs the processing of steps S1 to S4 on the wafer W, and includes, for example, a circular processing container 51. That is, the processes of steps S1 to S4 are performed in the same processing container. The processing container 51 is an airtight vacuum container, and a circular mounting table (stage) 61 on which the wafer W is placed on a horizontally formed surface (upper surface) is provided on the lower side of the processing container 51. ing. In the figure, reference numeral 62 denotes a stage heater embedded in the mounting table 61, which heats the wafer W to a predetermined temperature so that the above steps S1 to S4 can be performed. Reference numeral 63 denotes a support column that supports the mounting table 61, which is a mounting portion, on the bottom surface of the processing container 51. In the figure, 64 is a vertical elevating pin, and the surface of the mounting table 61 is recessed by the elevating mechanism 65, and the wafer W is transferred between the second substrate transport mechanism 42 and the mounting table 61 described above. Three lifting pins 64 are provided, but only two are shown.

In the figure, reference numeral 66 denotes a side wall heater provided on the side wall of the processing container 51, which adjusts the temperature of the atmosphere inside the processing container 51. The side wall of the processing container 51 is provided with a transfer port for the wafer W which can be opened and closed (not shown). In the figure, 67 is an exhaust port opened on the bottom surface of the processing container 51, and is connected to an exhaust mechanism 68 composed of a vacuum pump, a valve, and the like via an exhaust pipe. By adjusting the exhaust flow rate from the exhaust port 67 by the exhaust mechanism 68, the pressure in the processing container 51 is adjusted.

Above the mounting table 61, on the ceiling of the processing container 51, a gas shower head 7 constituting a gas supply unit is provided so as to face the mounting table 61. The gas shower head 7 includes a shower plate 71, a gas diffusion space 72, and a diffusion plate 73. The shower plate 71 is horizontally provided so as to form a lower surface portion of the gas shower head 7, and a large number of gas discharge holes 74 are dispersed and formed in order to discharge gas into the mounting table 61 in a shower shape. The gas diffusion space 72 is a flat space formed so that the lower side thereof is partitioned by the shower plate 71 in order to supply gas to each gas discharge hole 74. A diffusion plate 73 is horizontally provided so as to divide the gas diffusion space 72 into upper and lower parts. Reference numeral 75 in the figure is a through hole formed in the diffusion plate 73, and a large number of through holes are dispersed and perforated in the diffusion plate 73. Reference numeral 77 in the figure is a ceiling heater, which adjusts the temperature of the gas shower head 7.

The downstream ends of the

gas supply pipes

78 and 81 are connected to the upper side of the gas diffusion space 72. The upstream side of the gas supply pipe 78 _{is connected to the F 2} gas supply source 70 via the flow rate adjusting unit 79. The flow rate adjusting unit 79 is composed of a valve and a mass flow controller, and adjusts the flow rate of the gas supplied to the downstream side of the gas supply pipe 78. Each flow rate adjusting unit, which will be described later, has the same configuration as the flow rate adjusting unit 79, and adjusts the flow rate of the gas supplied to the downstream side of the pipe through which the flow rate adjusting unit is provided.

The upstream side of the gas supply pipe 81 is connected to the tank 83 in which the liquid amine is stored via the flow rate adjusting unit 82. The tank 83 is provided with a heater that heats and vaporizes the amine inside, and is configured to be able to supply the vaporized amine (amine gas) to the downstream side of the gas supply pipe 81. Further, for example, the gas supply pipe 81 branches on the upstream side of the flow rate adjusting unit 82 to form the gas supply pipe 84. _{The gas supply pipe 84 is connected to the N 2} (nitrogen) supply source 86 via the flow rate adjusting unit 85. Therefore, the amine gas and the N ₂ gas can be independently supplied to the gas shower head 7. In the figure, 52 is a heater provided in the gas supply pipe 81.

The correspondence between the above steps S1 to S4 performed in the etching module 5 and the gas supplied from the gas shower head 7 will be described. In step S1, amine gas is supplied to the gas shower head 7 from the tank 83 described above, and is supplied into the processing container 51. In step S2, S4, _{N 2} gas from the _{N 2} gas supply source 86 is supplied to the gas shower head 7, is supplied as a purge gas into the processing vessel 51. In step S3, the supply of gas from the tank 83 and the N ₂ gas supply source 86 is stopped, the F ₂ gas is supplied from the supply source 70 to the gas shower head 7, and is supplied into the processing container 51.

In performing each of the processes of steps S1 to S4 described above, the temperature of the wafer W is set to, for example, 0 ° C. to 150 ° C. The pressure in the processing container 51 during processing is, for example, 13.3 Pa (100 mTorr) to 666.5 Pa (5000 mTorr). The flow rate of the F ₂ gas supplied into the processing container 51 is, for example, 100 sccm to 2000 sccm, and the flow rate of the amine gas such as butylamine supplied into the processing container 51 is, for example, 1 sccm to 500 sccm.

By the way, as shown in FIGS. 8 and 9, the substrate processing device 3 includes a control unit 30 which is a computer, and the control unit 30 includes a program, a memory, and a CPU. The program incorporates instructions (each step) for processing the wafer W and transporting the wafer W as described above, and the program includes computer storage media such as a compact disk, a hard disk, and a magneto-optical disk. It is stored in a DVD or the like and installed in the control unit 30. The control unit 30 outputs a control signal to each unit of the substrate processing device 3 by the program, and controls the operation of each unit. Specifically, the operation of the etching module 5, the operation of the heat treatment module 40, the operation of the first substrate transfer mechanism 32, the operation of the second substrate transfer mechanism 42, and the operation of the oriental chamber 36 are controlled by control signals. The operations of the etching module 5 include adjusting the output of each heater, supplying and stopping each gas from the gas shower head 7, adjusting the exhaust flow rate by the exhaust mechanism 68, and raising and lowering the lifting pin 64 by the lifting mechanism 65. The operation is included. An etching apparatus is configured by the control unit 30 and the etching module 5.

The transfer path of the wafer W in the substrate processing apparatus 3 will be described. As described with reference to FIG. 1, a carrier 34 containing a wafer W on which each film is formed is placed on a carrier mounting table 35. Then, the wafer W is conveyed in the order of the normal pressure transfer chamber 33 → the oriental chamber 36 → the normal pressure transfer chamber 33 → the load lock chamber 41, and is conveyed to the etching module 5 via the heat treatment module 40. Then, as described above, the cycle consisting of steps S1 to S4 is repeatedly performed to process the wafer W. Subsequently, the wafer W is conveyed to the heat treatment module 40 and undergoes the process of step S5. After that, the wafer W is conveyed in the order of the load lock chamber 41 → the normal pressure transport chamber 33, and is returned to the carrier 34.

By the way, when the supply of the amine gas and the supply of the etching gas are performed in order, the supply of the amine gas and the supply of the etching gas are performed in different processing containers, and the wafer W is moved between these processing containers by the transport mechanism. It may be configured to be transported. However, by supplying these gases in the same processing container, it is possible to save the time for transporting the wafer W between the modules in repeating the above cycle. Therefore, according to the configuration of the substrate processing device 3, the throughput can be improved.

It should be noted that the embodiments disclosed this time are exemplary in all respects and are not considered to be restrictive. The above embodiments may be omitted, replaced, modified and / or combined in various forms without departing from the scope of the appended claims and their gist.

(Evaluation test)
An evaluation test conducted in connection with the technique of the present disclosure will be described.
・ Evaluation test 1
As evaluation test 1, etching was performed by supplying butylamine gas together with _{F 2 gas to the Si film on the substrate.} After this treatment, the etching amount of the Si film (thickness of the etched film) and the roughness of the surface of the remaining Si film were measured. The temperature of the substrate at the time of etching, the pressure in the processing container for storing the substrate, _{the flow rate of F 2} gas into the processing container, and the flow rate of butylamine gas into the processing container are described in the embodiments. Processing was performed by setting the value in the range. Further, as a comparative test 1 _{, etching was performed in the same manner as in the evaluation test 1 except that NH 3} gas was supplied instead of the butylamine gas, and the etching amount of the Si film and the roughness of the surface of the Si film were measured.

The graph of FIG. 10 shows the results of the evaluation test 1 and the comparative test 1. As shown in the graph, the etching amount is 65.0 nm in the evaluation test 1 and 46.0 nm in the comparative test 1, and the evaluation test 1 is larger. _{Therefore, by supplying the F 2} gas and the NH ₃ gas as described in the embodiment, the etching amount per unit time can be increased.

Regarding the roughness of the surface of the Si film, the evaluation test 1 has a roughness of 5.8 nm and the comparative test 1 has a roughness of 12.6 nm, and the evaluation test 1 is smaller. That is, in the evaluation test 1, the roughness of the Si film after etching is suppressed. In the above embodiment, an example of removing all the polysilicon film 14 which is a Si film has been shown, but this technique can also be applied to a process of etching only a part of the Si film. In that case, it is advantageous because it is possible to suppress the occurrence of defects due to the influence of the unevenness on the surface of the Si film for each treatment performed after the etching of the Si film.

・ Evaluation test 2
As evaluation test 2, the adsorption energies of various molecules containing Si for _{NH 3} , butylamine, hexylamine, and trimethylamine, which are molecules containing N (nitrogen), were measured by simulation. Specifically, the adsorption energies for Si, SiC (silicon carbide), SiN (silicon nitride), SiO ₂ CN (= SiO CN), and SiO (silicon oxide) were measured.

FIG. 11 is a bar graph showing the results of this evaluation test 2. The vertical axis of the graph shows the adsorption energy (unit: eV), and the lower the adsorption energy, the easier it is to adsorb. As shown in FIG. 11, it is _{difficult to adsorb any of NH 3} , butylamine, hexylamine and trimethylamine to Si, SiC and SiN. However _{, NH 3} , butylamine, hexylamine and trimethylamine are all easily adsorbed on _{SiO 2} CN and SiO. This is because the adsorption sites of amines and ammonia are O atoms.

From the results of this evaluation test 2, the difference in the adsorptivity of amines between the Si film, the silicon oxide film and the SiOCN film is utilized to protect the silicon oxide film and the SiOCN film as described in the embodiment, while Si. It can be estimated that selective etching of the film is possible. Further, it can be estimated that the pores can be sealed by adsorbing amines on the pore walls of the SiOCN film.

・ Evaluation test 3
As evaluation test 3, butylamine gas was supplied to a substrate having different types of films on each surface. Then, the amount of butylamine adsorbed on each film was measured by a gas chromatograph mass spectrometer (GC-MS).

FIG. 12 shows the result of this evaluation test 3. As shown in the figure, the adsorption amount of the polysilicon (Poly-Si) film and the amorphous silicon (α-Si) film is approximately 0 ng / cm ² . The adsorption amount on the silicon oxide film is approximately 0.10 ng / cm ² , and the adsorption amount on the SiOCN film is approximately 0.27 ng / cm ² . Therefore, it was shown that the adsorbability of amine is larger in the Si film (silicon oxide film and SiOCN) containing oxygen than in the Si film (polysilicon film and amorphous silicon film). Therefore, from the result of the evaluation test 3, as in the result of the evaluation test 2, it is possible to selectively etch the Si film as shown in the embodiment by utilizing the difference in the adsorptivity of amines. Presumed.

W Wafer 14 polysilicon film 21 amine 22 fluorine gas

Claims

An etching method that includes a step of supplying fluorine gas and amine gas to a substrate having a silicon film formed on the surface and etching the silicon film.
The etching method according to claim 1, wherein the step of etching the silicon film includes a step of supplying the fluorine gas and the amine gas to the substrate at 0 ° C. to 150 ° C.
In the step of etching the silicon film, the pressure in the processing container for accommodating the substrate is set to 13.3 Pa to 666.5 Pa.
The etching method according to claim 1, further comprising a step of supplying the fluorine gas and the amine gas into the processing container.
The fluorine gas and the amine gas are supplied to the substrate on which the silicon film and the silicon film containing oxygen are formed on the surface, and the step of etching the silicon film is the silicon film and the silicon film containing oxygen. The etching method according to claim 1, which comprises a step of selectively etching the silicon film.
In the substrate, the silicon film, the first film, and the silicon-containing film, which is the second film having etching resistance to the fluorine gas, are provided next to each other in this order.
The first film and the second film are silicon films containing oxygen, and the first film is provided with holes that open into the silicon film and the second film.
The step of etching the silicon film is
A step of adsorbing an amine on the pore wall forming the pore portion of the first film, and
The step of supplying the fluorine gas to the substrate on which amine is adsorbed on the pore wall, and
The etching method according to claim 1.
The etching method according to claim 5, wherein the first film is a porous film.
The etching method according to claim 1, wherein the step of supplying the amine gas and the step of supplying the fluorine gas are repeated a plurality of times in this order.
The etching method according to claim 1, further comprising a step of exhausting the periphery of the substrate between the period of supplying the amine gas and the period of supplying the fluorine gas.
The etching method according to claim 1, wherein the supply of the fluorine gas to the substrate and the supply of the amine gas to the substrate are performed at the same time.
The etching method according to claim 1, further comprising a heating step of heating the substrate in order to remove amine from the substrate after performing the step of etching the silicon film.
Processing container and
A stage on which a substrate provided in the processing container and having a silicon film formed on the surface is placed, and
A gas supply unit that supplies amine gas and fluorine gas into the processing container for etching the silicon film, and
Etching equipment including.