TWI813607B - Etching method and etching device - Google Patents

Abstract

[Problem] When supplying an etching gas to a substrate in which a silicon-containing film, a porous film, and a non-etching target film are arranged adjacent to each other in the transverse direction to remove the silicon-containing film, prevent etching of the non-etching target film. [Solution] Implement the following process: supply film-forming gases (21, 22), and supply etching gas (24) to prevent etching of the silicon-containing film (14) through the pores (16) of the porous film (15) A film forming process in which a passage prevention film (23) to the non-etching target film (11) is formed in the hole portion (16); and in a state where the passage prevention film (23) is formed, the etching gas (24) is supplied to The silicon-containing film (14) performs an etching process.

Description

Etching method and etching device

The present invention relates to a technology for etching a silicon-containing film formed adjacent to a porous film on a substrate.

The interlayer insulating film that fills the wiring constituting the semiconductor device may be formed of a low dielectric constant film called a low-k film. The low-k film may be formed of, for example, a porous film. In the manufacturing process of semiconductor devices, a semiconductor wafer (hereinafter referred to as a wafer) on which such a porous film is formed may be etched.

For example, Patent Document 1 discloses that a wafer on which an interlayer insulating film of a low-k film is formed is etched to form a recessed portion for filling wiring. A film is formed in the recessed portion for the purpose of preventing the wiring from being exposed to the atmosphere by supplying the film-forming gas until the wiring is filled in the recessed portion. Furthermore, Patent Document 2 discloses a technology of etching an organic film formed in a recess of a low dielectric constant film, which is a porous film, and embedded in a recessed portion, using a plasma containing a treatment gas containing a predetermined amount of carbon dioxide. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2016-63141 [Patent Document 2] Patent No. 4940722

[Problem to be solved by the invention]

When manufacturing a semiconductor device, a laminated body composed of a polycrystalline silicon film, a porous SiOCN film, a silicon oxide film on the upper side, and a SiGe (silicon germanium) film on the lower side is formed so as to be adjacent to each other in the lateral direction. There are cases where the polycrystalline silicon film is removed from the wafer surface. If the polycrystalline silicon film is removed by dry etching, the etching gas is supplied to the SiGe film through the SiOCN film during etching of the polycrystalline silicon film. More specifically, since the SiOCN film is a porous film, the etching gas is supplied from the side of the SiOCN film through the pores of the porous film to the side wall of the SiGe film. Although the SiGe film is not a target to be removed by etching, the side wall is etched because the etching gas is supplied in this way.

Here, for example, after removing the upper side of the polycrystalline silicon film by anisotropic etching using plasma, there may be a case where a process of removing the lower side of the polycrystalline silicon film by wet etching is performed. The etching liquid used in the wet etching has lower permeability to the SiOCN film than the above-mentioned etching gas, thereby inhibiting etching of the SiGe film. However, it takes a lot of time to perform multiple processes in this way, and the processing accompanying the miniaturization of the device in the wet etching process becomes impossible. In addition, the thickness of the side wall of the SiOCN film tends to become smaller. The thickness of the side wall of the SiOCN film will become smaller in the future. When the size is further reduced, the permeability of the etching liquid to the SiOCN film increases, and the SiGe film may be etched. The technologies described in the above-mentioned Patent Documents 1 and 2 cannot solve such problems.

The present invention was made in view of such a situation, and an object thereof is to provide a method for removing a silicon-containing film (including silicon itself) by supplying an etching gas to a substrate in which a silicon-containing film, a porous film, and a non-etching target film are arranged adjacent to each other in the transverse direction. ), a technology that can prevent non-etching target films from being etched. [Means used to solve problems]

The etching method of the present invention is characterized by comprising: A film-forming gas is supplied to a substrate in which a silicon-containing film, a porous film, and a non-etching target film are arranged adjacent to one another in the transverse direction, and the etching gas used to prevent etching of the silicon-containing film is passed through the pores of the porous film. A film forming process in which the passage prevention film supplied to the non-etching target film is formed in the hole portion; and An etching process in which the etching gas is supplied to etch the silicon-containing film.

The etching device of the present invention is characterized by comprising: processing containers; A placement portion is provided in the above-mentioned processing container and is used for placing a substrate in which a silicon-containing film, a porous film, and a non-etching target film are arranged adjacent to each other in the transverse direction; The film-forming gas supply unit is configured to provide a pass-prevention film on the processing container in order to prevent the etching gas from etching the silicon-containing film from being supplied to the non-etching target film through the hole portion of the porous film. Film-forming gas is supplied internally; and The etching gas supply unit supplies the etching gas into the processing container. [Effects of the invention]

According to the present invention, a film-forming gas is supplied to a substrate in which a silicon-containing film, a porous film, and a non-etching target film are arranged adjacent to each other in the transverse direction, and a passage preventing film is formed in the hole portion of the porous film. The protective film prevents the etching gas used to etch the silicon-containing film from being supplied to the non-etching target film. Accordingly, when etching the silicon-containing film, etching of the non-etching target film is suppressed.

FIG. 1 is a vertical cross-sectional side view of the surface of a wafer W subjected to processing according to an embodiment of the present invention. 11 in the figure is a SiGe film, and a silicon oxide (SiO _x ) film 12 is laminated on the side of the SiGe film 11 . A recessed portion 13 is formed in the laminate of the silicon oxide film 12 and the SiGe film 11, and the polysilicon film 14 is filled in the recessed portion 13. In addition, a SiOCN film 15 is provided between the side wall of the polycrystalline silicon film 14 and the side wall of the recessed portion 13, which surrounds the side of the polycrystalline silicon film 14 and is in contact with the side wall of the polycrystalline silicon film 14 and the side wall of the recessed portion 13 respectively. That is, it is composed of silicon, A membrane composed of oxygen, nitrogen and carbon. Therefore, when viewed from the lateral direction, the polycrystalline silicon film 14 , the SiOCN film 15 , and the SiGe film 11 are formed in order to be adjacent to each other. The SiOCN film 15 is an interlayer insulating film and is a porous film.

The process in the embodiment of the present invention is summarized as follows, and is repeated alternately: Supply of film-forming gas to form a polymer (polyurea) with urea bonds in the hole portion of the SiOCN film 15, that is, a polyurea film. , and supply of etching gas for etching the polycrystalline silicon film 14 which is the film to be etched. That is, the polysilicon film 14 is etched at intervals, and the polyurea film is formed to fill the holes between etchings. This prevents the etching gas from penetrating the SiOCN film 15 from the side of the SiOCN film 15 and etching the sidewall of the SiGe film 11 which is not the film to be etched.

The silicon oxide film 12 serves as an etching mask film when the polycrystalline silicon film 14 is etched. In addition, the etching gas has low etching selectivity to the silicon oxide film 12 and the polyurea film, and has high etching selectivity to the polycrystalline silicon film 14. Therefore, for example, IF ₇ (iodine heptafluoride) gas is used. Considering that the IF ₇ gas has a large molecular weight and is difficult to pass through the pores of the SiOCN film 15 , it is expected that the supply to the SiGe film 11 can be suppressed more reliably, which is preferable.

In this embodiment, a first film-forming gas containing an amine as a monomer and a second film-forming gas containing an isocyanate as a monomer are supplied to the wafer W to cause a polymerization reaction to form the polyurea film. As the amine, for example, 1,3-bis(aminomethyl)cyclohexane (H6XDA) is used, and as the isocyanate, for example, 1,3-bis(methyl isocyanate)cyclohexane (H6XDI) is used. In addition, hexylamine may be used as the amine, and tert-butyl isocyanate may be used as the isocyanate. In addition, the amine and isocyanate that can form the polyurea film are not limited to this example, and specific examples will be given later.

Next, the processing of the wafer W will be described with reference to FIGS. 2 to 4 . 2 to 4 are schematic diagrams illustrating how the surface of the wafer W illustrated in FIG. 1 changes through processing. In the figure, the hole formed in the SiOCN film 15 is marked as 16, the amine, which is the first film-forming gas, is marked as 21, the isocyanate, which is the second film-forming gas, is marked as 22, the polyurea film is marked as 23, and IF ₇ is The etching gas is marked 24. In addition, each process shown in FIGS. 2 to 4 is performed in a state where the wafer W is loaded into the processing container and the inside of the processing container is exhausted to a vacuum atmosphere of a predetermined pressure.

First, the first film-forming gas 21 is supplied into the processing container (step S1, FIG. 2(a)). The first film-forming gas 21 flows into the hole portion 16 on the upper side of the SiOCN film 15 and is adsorbed to the hole wall. Next, the supply of the first film-forming gas 21 in the processing container is stopped, and the exhaust gas and, for example, N ₂ (nitrogen) gas, that is, a clean gas, are supplied into the processing container (step S2, FIG. 2(b)). The first film-forming gas 21 that has not flowed into the hole portion 16 is removed by the flow of exhausting clean gas.

Next, the second film-forming gas 22 is supplied into the processing container (step S3, FIG. 2(c)). The second film-forming gas 22 flows into the hole portion 16 on the upper side of the SiOCN film 15 and is adsorbed in the hole portion 16. The first film-forming gas 21 reacts to form a polyurea film 23 that is a film that prevents the etching gas from passing through, and the hole portion 16 is blocked. After that, the supply of the second film-forming gas 22 in the processing container is stopped, and the exhaust gas and the clean gas are supplied into the processing container (step S4, FIG. 2(d)). The membrane gas 22 is removed by a flow of exhausting clean gas.

Next, the etching gas 24 is supplied into the processing chamber (step S5, FIG. 3(e)), the polycrystalline silicon film 14 is etched, and the upper side wall of the SiOCN film 15 is exposed. At this time, the hole portion 16 on the upper side of the SiOCN film 15 is filled with the polyurea film 23, and the polyurea film 23 is not easily etched by the etching gas 24. Therefore, the etching gas 24 is prevented from passing through the hole portion 16, and the etching gas 24 can be prevented from permeating from the side of the SiOCN film 15 and etching the side wall of the SiGe film 11. After that, the supply of the etching gas 24 in the processing container is stopped, and the exhaust gas and the cleaning gas are supplied to the processing container (step S6, FIG. 3(f)). The etching gas 24 remaining in the processing container passes through the processing container. The flow of clean gas exhausted from the treatment vessel is removed.

Thereafter, the first film-forming gas 21 is supplied into the processing container. That is, step S1 is executed again. In the above-mentioned step S5, the polycrystalline silicon film 14 is exposed by etching the upper side wall of the SiOCN film 15. Therefore, the first film-forming gas 21 supplied in the second step S1 is supplied to and from the SiOCN film 15. The hole portion 16 to which the first film-forming gas 21 was supplied in the first step S1 is adsorbed to the hole wall compared to the hole portion 16 located further below.

After that, the exhaust gas and the clean gas in the processing container are supplied again in step S2, and then the second film-forming gas 22 in the processing container is supplied in step S3 again. The second film-forming gas 22 is also supplied to the processing chamber to which the second film-forming gas 22 was supplied in the first step S3, similarly to the first film-forming gas 21 supplied into the processing container in the second step S1. The hole portion 16 of the SiOCN film 15 of the film gas 22 becomes the hole portion 16 located lower than the hole portion 16 , and reacts with the first film-forming gas 21 adsorbed by the hole portion 16 to form the polyurea film 23 . Therefore, in the second step S3, the area in the SiOCN film 15 where the polyurea film 23 is formed expands downward (Fig. 4(a)).

Thereafter, after the exhaust gas and the clean gas are supplied in step S4, the etching gas 24 is supplied in step S5. The polycrystalline silicon film 14 is further etched downward, and the exposed area in the side wall of the SiOCN film 15 expands downward. As described above, the area in which the polyurea film 23 is formed in the SiOCN film 15 is expanded from the downward direction through the second step S3. Accordingly, the holes near the side walls of the SiOCN film 15 are newly exposed through the etching of the polycrystalline silicon film 14. The portion 16 is filled with the polyurea film 23 . Therefore, in the second step S5, it is also possible to prevent the etching gas from etching the sidewall of the SiGe film 11 through the holes 16 of the SiOCN film 15 (FIG. 4(b)). After the etching, the exhaust gas and the supply of clean gas in step S6 are performed again.

The steps S1 to S6 performed in this order are regarded as one cycle. For example, the cycle is repeated after the second step S6 described above. The polyurea film 23 formed downward in the SiOCN film 15 prevents the The sidewalls of the SiGe film 11 are etched, and the polysilicon film 14 is etched downward. For example, after all the polycrystalline silicon film 14 is etched and a predetermined number of cycles are completed ( FIG. 4( c )), the wafer W is heated at, for example, 100° C. or higher, preferably 300° C. or higher, to remove the polyurea filled in the hole 16 . The film 23 is vaporized or depolymerized and vaporized, and is removed from the wafer W (Fig. 4(d)). The etching residue adhered to the surface of the wafer W is also vaporized and removed simultaneously with the polyurea film 23 by this heating (step S7). FIG. 5 shows the wafer W in which the polycrystalline silicon film 14 has been etched and the polyurea film 23 has been removed. In the recessed portion 17 formed by removing the polycrystalline silicon film 14, for example, a gate of a semiconductor device is formed in a subsequent process.

According to the processing of the embodiment of the invention described above, it is possible to prevent the SiGe film 11 from being etched by the etching gas, and at the same time, the polycrystalline silicon film 14 can be etched by the etching gas. Furthermore, in the processing according to the embodiment of the present invention, compared with the case where the plasma processing is followed by wet etching described in the prior art, it is not necessary to switch the atmosphere around the wafer W from the vacuum atmosphere in which the plasma processing is performed. Atmospheric atmosphere for wet etching. Therefore, the processing according to the embodiment of the present invention has the advantage that the time and effort required for the processing can be reduced. In addition, the processing according to this embodiment does not require the use of plasma, so the films on the surface of the wafer W will not be damaged by the plasma, which also has the advantage of improving the reliability of the semiconductor device formed from the wafer W. However, etching using plasma is also included in the scope of rights of the present invention.

The exhaust gas flow rate of the processing container in the above-mentioned steps S1 to S6 may be constant. Regarding the removal of unnecessary gas in the processing container, the exhaust gas flow rate in steps S2, S4, and S6 is determined in a manner that can remove the gas more reliably. The exhaust flow rate may be set larger than the exhaust flow rate in steps S1, S3, and S5. In addition, in steps S2, S4, and S6, the supply of clean gas may not be performed, and unnecessary gas may be removed only by exhaust gas. In addition, as mentioned above, the etching gas IF ₇ gas has low etching selectivity for the polyurea film 23. Therefore, if the polyurea film 23 is formed on the surface of the polycrystalline silicon film 14, the polycrystalline silicon film 14 will be difficult to be etched. However, the first film-forming gas 21 and the second film-forming gas 22 that are unnecessary in the aforementioned steps S2 and S4 are removed. That is, by performing steps S2 and S4, the polycrystalline silicon film 14 can be etched more reliably.

However, a silicon-containing film other than the polycrystalline silicon film 14 may be used as the film to be etched. The silicon-containing film system includes a film containing silicon as a main component. Specifically, an amorphous silicon film, a single crystal silicon film, a SiGe film, etc. are included in the silicon-containing film. The etching gas may be any gas capable of etching the silicon-containing film. Specifically, as the etching gas, in addition to IF ₇ gas, for example, fluorine (F ₂ ) gas, ClF ₃ (chlorine trifluoride), IF ₅ (iodine pentafluoride) gas, BrF ₃ (bromine trifluoride) can be used. ) and other gases containing fluorine.

In the above embodiment, the non-etching target film is the SiGe film 11, but it may be a Si film, for example. In addition, the non-etching target film may be a film other than a silicon-containing film such as those Si films or the SiGe film 11 . In addition, the mask film provided on the SiGe film 11 is not limited to the silicon oxide film 12 as long as it can prevent the SiGe film 11 from being etched from the upper side during etching. In addition, the porous film is not limited to the SiOCN film 15. Instead of the SiOCN film 15, a porous film such as a SiCO film or a SiCOH film may be formed.

In addition, the film-forming gas used to form the polyurea film 23 is not limited to the above example. For example, 1,12-diaminododecane (DAD) can be used as the amine, diphenylmethane diisocyanate (MDI) can be used as the isocyanate, DAD can be used as the amine, H6XDI can be used as the isocyanate, and hexane diisocyanate can be used as the amine. Amine, H6XDI can be used as isocyanate. However, as the amine, in addition to the above-mentioned compounds, for example, 1,6-hexanediamine, cyclohexylamine, hexylamine, butylamine, and tert-butylamine can be used. As the isocyanate, in addition to the above-mentioned compounds, for example, 1,6-hexamethylene diisocyanate, cyclohexyl isocyanate, hexyl isocyanate, butyl isocyanate, and tert-butyl isocyanate can be used. That is, a compound selected from among the amine compounds listed above and a compound selected from the isocyanate compounds listed above can be used for the film formation of the polyurea film 23 . If the change in the reaction between isocyanate and amine is further explained, in this reaction, as shown in Figure 6, a functional molecule can also be used as the raw material monomer constituting the film-forming gas. Alternatively, polyurea may be depolymerized and vaporized by heating and the gas generated may be supplied to the wafer W as a film-forming gas. The gas may be cooled and adsorbed on the surface of the wafer W to undergo a polymerization reaction, and the polyurea film may be formed again. . Therefore, the film-forming gas is not limited to supplying two types of the first film-forming gas and the second film-forming gas to the wafer W.

In the processing example illustrated in FIGS. 2 to 4 , steps S1 to S6 are performed three or more times, but steps S1 to S6 may be performed two or more times. In step S7, the wafer W is heated so that the polyurea film 23 is removed from the SiOCN film 15. However, if the polyurea film 23 remains in the hole portion 16 of the SiOCN film 15, the dielectric constant of the SiOCN film 15 is If there is no problem in practice, it may be considered to leave the polyurea membrane 23 remaining. Therefore, the case where the polyurea film 23 is not removed in step S7 is also included in the scope of rights of the present invention.

Next, the substrate processing apparatus 3 that performs the series of processes described in FIGS. 2 to 4 will be described with reference to the plan view of FIG. 7 . The substrate processing apparatus 3 includes a load lock chamber 31 for loading and unloading the wafer W; two load lock chambers 41 adjacent to the load lock chamber 31; and two load lock chambers 41 adjacent to each of the two load lock chambers 41. The heat treatment module 40; and the two etching modules 5 respectively arranged adjacent to the two heat treatment modules 40.

The unloading and unloading unit 31 includes a normal pressure transfer chamber 33 provided in the first substrate transfer mechanism 32 and set to a normal pressure atmosphere. It is provided on a side of the normal pressure transfer chamber 33 and is used to place and accommodate the wafer W. The wafer carrier mounting table 35 of the round carrier 34 is provided. Reference numeral 36 in the figure is an orienter chamber adjacent to the normal pressure transfer chamber 33. It is installed to rotate the wafer W and calculate the eccentricity using an optical formula to position the wafer W and the first substrate transfer mechanism 32. The first substrate transport mechanism 32 transports the wafer W between the wafer carrier 34 on the wafer carrier mounting table 35 and the orienter chamber 36 and load lock chamber 41 .

A second substrate transfer mechanism 42 having, for example, a multi-joint arm structure is provided in each load lock chamber 41. The second substrate transfer mechanism 42 transfers wafers between the load lock chamber 41, the heat treatment module 40, and the etching module 5. W. The inside of the processing vessel constituting the heat treatment module 40 and the processing vessel constituting the etching module 5 are set to a vacuum atmosphere, and the inside of the load lock chamber 41 can be connected between the processing vessels in the vacuum atmosphere and the normal pressure transfer chamber 33. The method of transferring the wafer W is switched between a normal pressure atmosphere and a vacuum atmosphere.

43 in the figure is a gate valve that can be opened/closed, respectively installed 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. . The thermal processing module 40 includes the above-mentioned processing container, an exhaust mechanism for evacuating the inside of the processing container to form a vacuum atmosphere, a mounting table installed in the processing container and capable of heating the placed wafer W, and is configured as follows. The aforementioned step S7 can be executed.

Next, the etching module 5 will be described with reference to the longitudinal sectional side view of FIG. 8 and the transverse sectional plan view of FIG. 9 . The etching module 5 includes, for example, a circular processing container 51 , and the wafer W can be processed in steps S1 to S6 in the processing container 51 . That is, etching and film formation can be performed in a common processing container 51 . The processing container 51 is an airtight vacuum container, and a circular mounting table 61 for mounting the wafer W on a horizontal surface (upper surface) is provided at the lower side of the processing container 51 . Reference numeral 62 in the figure is a stage heater embedded in the mounting table 61, which heats the wafer W to a predetermined temperature in such a manner that the above-mentioned steps S1 to S6 can be performed. Reference numeral 63 in the figure is a support column that supports the mounting table 61 which is the mounting part on the bottom surface of the processing container 51 . Reference number 64 in the figure represents three vertical lifting pins. The lifting mechanism 65 can protrude/retract from the surface of the mounting table 61 to transfer the wafer W between the aforementioned second substrate transport mechanism 42 and the mounting table 61 .

The lower side of the side wall of the processing container 51 protrudes toward the center side of the processing container 51 when viewed from a plan view and is close to the side of the mounting table 61 to form an annular lower section 52 in a plan view. The upper surface of the lower section 52 is horizontal, for example, formed to be at the same height as the surface of the mounting base 61 . In the side wall of the processing container 51 , the upper side of the lower section 52 serves as the side wall body 53 . As will be described later, the film-forming gas (the first film-forming gas and the second film-forming gas) is ejected in such a manner that it collides with the side wall body portion 53 forming the member to be collided, and the lower section 52 has a structure for transporting the film-forming gas ejected in this way. to the upper surface and supplied to the role of the guide member on the mounting table 61 . 54 in the figure indicates side wall heaters which are respectively embedded in the lower section 52 and the side wall body 53 . The side wall heater 54 adjusts the temperature of the lower section 52 inside the processing container 51 and the surface of the side wall body 53 , the temperature of the film-forming gas that collides with the side wall body 53 and the atmosphere in the processing container 51 The temperature is adjusted.

55 in FIG. 8 is a transfer port for the wafer W. An opening is provided in the side wall body portion 53 at a location away from the circumferential direction of the processing container 51 where the film-forming gas collides. The gate valve 43 can be freely opened/closed. composition. Reference numeral 66 in the figure indicates an exhaust port provided in an opening on the bottom surface of the processing container 51, and is connected to an exhaust mechanism 67 (see FIG. 8) composed of a vacuum pump, a valve, etc. via an exhaust pipe. By adjusting the exhaust flow rate through the exhaust port 66 of the exhaust mechanism 67, the pressure within the processing container 51 is adjusted.

The gas shower head 7 forming the etching gas supply part is installed above the mounting table 61 and in the ceiling part of the processing container 51 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 installed horizontally to form the lower surface of the gas shower head 7. In order to spray the gas in a shower shape to the mounting table 61, a plurality of gas discharge holes 74 are formed in a dispersed manner. The lower side of the gas diffusion space 72 is a flat space divided by the shower plate 71 in order to supply gas to each gas discharge hole 74 . The diffusion plate 73 is installed horizontally so as to divide the gas diffusion space 72 into upper and lower parts. Reference numeral 75 in the figure indicates a through hole formed in the diffusion plate 73 , and the diffusion plate 73 has a plurality of scattered holes. 77 in the figure is a patio heater, which adjusts the temperature of the gas shower head 7 .

The downstream end of the gas supply pipe 68 is connected to the upper side of the gas diffusion space 72 . The upstream side of the gas supply pipe 68 is connected to the IF ₇ gas supply source 60 via the flow rate adjusting portion 69 . The flow rate adjustment unit 69 is composed of a valve or a mass flow controller, and adjusts the flow rate of the gas supplied to the downstream side of the gas supply pipe 68 . In addition, each flow rate adjusting part to be described later is configured similarly to the flow rate adjusting part 69 and adjusts the flow rate of the gas supplied to the downstream side of the pipe in which the flow rate adjusting part is arranged.

A gas nozzle 8 that is a film-forming gas supply unit that supplies the film-forming gas (the first film-forming gas and the second film-forming gas) is provided on the side wall body 53 of the processing container 51 . That is, the film-forming gas system is supplied from a gas supply part provided separately from the gas shower head 7 . In addition, the gas nozzle 8 supplies the aforementioned clean gas in addition to the film-forming gas.

The gas nozzle 8 is formed in a rod shape extending laterally, for example. The dotted arrows in FIGS. 8 and 9 indicate the opening direction of the discharge port provided at the front end of the gas nozzle 8 , that is, the discharge direction of the gas. As shown by the arrows, the gas nozzle 8 ejects gas horizontally along the diameter of the wafer W. The side wall body 53 is located at the front end of the gas in the ejection direction, so the ejected gas first collides with the side wall body 53 before being supplied to the wafer W. That is, the gas outlet provided in the gas nozzle 8 does not face the wafer W, but faces the side wall body portion 53 which is the member to be collided. The gas that collides with the side wall body portion 53 in this way flows along the surface of the lower portion 52 and the surface of the mounting table 61 and is supplied to the wafer W as shown by the dotted arrow in FIG. 8 .

The gas nozzle 8 configured in this way has a structure in which the discharge port of the gas nozzle 8 directly faces the wafer W and the discharged gas is directly supplied to the wafer W. The discharged gas travels a longer distance before reaching the wafer W. Therefore, the purpose of fully diffusing the gas in the lateral direction can be achieved. That is, the gas nozzle 8 is configured to discharge the gas toward the side wall body portion 53 so that each gas can be supplied with high uniformity within the surface of the wafer W.

In FIG. 8 , 81 is a gas supply pipe, which is connected to the gas nozzle 8 from the outside of the processing container 51 . The gas supply pipe 81 is branched on the upstream side to form gas introduction pipes 82 and 83 . The upstream side of the gas introduction pipe 82 is connected to the vaporization part 92 via the flow rate adjustment part 91 and the valve V1 in this order. The above-mentioned H6XDA is stored in a liquid state in the vaporization part 92, and the vaporization part 92 is equipped with a heater (not shown) for heating the H6XDA. Furthermore, one end of the gas supply pipe 94 is connected to the vaporization part 92, and the other end of the gas supply pipe 94 is connected to the N ₂ (nitrogen) gas supply source 96 via the valve V2 and the gas heating part 95 in this order. With such a configuration, the heated N ₂ gas is supplied to the vaporization part 92 to vaporize the H6XDA in the vaporization part 92, and the mixed gas of the N ₂ gas and the H6XDA gas used in this vaporization is used as the first film-forming gas. is introduced into the gas nozzle 8.

In addition, the gas supply pipe 94 has a branch at a position on the downstream side of the gas heating part 95 and on the upstream side of the valve V2 to form a gas supply pipe 97. The end of the gas supply pipe 97 is connected to the gas introduction via the valve V3. The pipe 82 is on the downstream side of the valve V1 and on the upstream side of the flow rate adjusting portion 91 . Therefore, when the first film-forming gas is not supplied to the gas nozzle 8 , the N ₂ gas heated by the gas heating unit 95 can be introduced into the gas nozzle 8 by bypassing the vaporization unit 92 .

Moreover, the upstream side of the gas introduction pipe 83 is connected to the vaporization part 102 via the flow rate adjustment part 101 and the valve V4 in this order. The above-mentioned H6XDI is stored in a liquid state in the vaporization part 102, and the vaporization part 102 is equipped with a heater (not shown) for heating the H6XDI. Furthermore, one end of the gas supply pipe 104 is connected to the vaporization part 102, and the other end of the gas supply pipe 104 is connected to the N ₂ (nitrogen) gas supply source 106 via the valve V5 and the gas heating part 105 in this order. According to such a structure, the heated N ₂ gas is supplied to the vaporization part 102 to vaporize the H6XDI in the vaporization part 102, and a mixed gas of the vaporized N ₂ gas and the H6XDI gas is used as the second film formation The gas is introduced into the gas nozzle 8.

In addition, the gas supply pipe 104 has a branch at a position downstream of the gas heating part 105 and upstream of the valve V5 to form a gas supply pipe 107. The end of the gas supply pipe 107 is connected to the gas introduction via the valve V6. The pipe 83 is located on the downstream side of the valve V4 and on the upstream side of the flow rate adjusting part 101 . Therefore, when the second film-forming gas is not supplied to the gas nozzle 8 , the N ₂ gas heated by the gas heating unit 105 is introduced into the gas nozzle 8 by bypassing the vaporization unit 102 .

In order to prevent H6XDA and H6XDI in the circulating film-forming gas from liquefying the gas supply pipe 81 and the gas introduction pipes 82 and 83, for example, a pipe heater 76 for heating the inside of the pipe is provided around each pipe. The temperature of the film-forming gas discharged from the gas nozzle 8 is adjusted by the heaters provided in the piping heater 76, the gas heating parts 95 and 105, and the vaporization parts 92 and 102. In addition, for the convenience of illustration, the pipe heater 76 is only shown in part of the gas supply pipe 81 and the gas introduction pipe 82 and 83, but it is installed in a relatively wide range throughout these pipes in a manner that can prevent the above-mentioned liquefaction. .

The upstream side of the flow rate adjustment part 91 in the gas introduction pipe 82, the flow rate adjustment part 91, the vaporization part 92, the valves V1 to V3, the gas supply pipes 94 and 97, the gas heating part 95 and the N ₂ gas supply source 96 are 1st gas supply mechanism 9A. In addition, the upstream side of the flow rate adjustment part 101 in the gas introduction pipe 83, the flow rate adjustment part 101, the vaporization part 102, the valves V4 to V6, the gas supply pipes 104 and 107, the gas heating part 105 and the N ₂ gas supply source 106 Let this be a second gas supply mechanism 9B. As described above, the first gas supply mechanism 9A can supply the N ₂ gas or the first film-forming gas to the gas nozzle 8 , and the second gas supply mechanism 9B can supply the N ₂ gas or the second film-forming gas to the gas nozzle 8 .

However, as shown in FIG. 7 , the substrate processing apparatus 3 includes a control unit 30 that is a computer, and the control unit 30 includes a program, a memory, and a CPU. The program is combined with instructions (each step) for performing the processing of the wafer W and the transportation of the wafer W. The program is stored in a computer storage medium such as an optical disk, a hard disk, an optical disk, a DVD, etc., and is Installed in the control unit 30. The control unit 30 outputs control signals to each unit of the substrate processing apparatus 3 according to the program to control the operation of each unit. Specifically, the control signals control the operations of the etching module 5 , the heat treatment module 40 , the first substrate transport mechanism 32 , the second substrate transport mechanism 42 , and the positioner chamber 36 . The operations of the etching module 5 include adjustment of the output of each heater, supply/cutoff of the IF ₇ gas from the first gas supply mechanism 9A, the second gas supply mechanism 9B, the gas shower head 7, Various operations include supply/cutoff of each gas from the nozzle 8, adjustment of the exhaust gas flow rate by the exhaust mechanism 67, and lifting and lowering of the lift pin 64 by the lift mechanism 65. The control unit 30 and the etching module 5 are equivalent to the etching device of the present invention.

The transfer path of the wafer W in the substrate processing apparatus 3 will be described. As illustrated in FIG. 1 , a wafer carrier 34 storing wafers W on which respective films are formed is placed on a wafer carrier mounting table 35 . Next, the wafer W is transported in the order of the normal pressure transfer chamber 33 → the locator chamber 36 → the normal pressure transfer chamber 33 → the load lock chamber 41, and is transferred to the etching module 5 via the heat treatment module 40. As described above, the cycle consisting of steps S1 to S6 is repeated, and the wafer W is processed. Next, the wafer W is transported to the thermal processing module 40 to undergo processing in step S7. Thereafter, the wafer W is transported in the order of the load lock chamber 41 → the normal pressure transfer chamber 33 and returned to the wafer carrier 34 .

Next, regarding the correspondence between the above-mentioned steps S1 to S6 performed in the etching module 5 and the gas supplied by the first gas supply mechanism 9A and the second gas supply mechanism 9B provided in the etching module 5, refer to Figs. 10 to 10 13 for explanation. The first film-forming gas and the N gas are supplied from the first gas supply mechanism 9A and the _N gas from the second gas supply mechanism 9B to the gas nozzle 8, and the mixed gases are discharged from the gas nozzle 8, and step S1 is performed (Fig. 10 ). Next, N 2 gas is supplied to the gas nozzle 8 from the first gas supply mechanism 9A and the second gas _{supply mechanism 9B, and the N 2 gas} is discharged as clean gas from the gas nozzle 8, and step S2 is performed ( FIG. 11 ). Thereafter, the _N gas is supplied from the first gas supply mechanism 9A and the second film-forming gas is supplied from the second gas supply mechanism 9B to the gas nozzle 8, and these mixed gases are discharged from the gas nozzle 8, and step S3 is performed ( Figure 12). Thereafter, in the same manner as step S2, N 2 gas is supplied to the gas nozzle 8 from the first gas supply mechanism 9A and the second gas _{supply mechanism 9B, and the N 2 gas} is discharged from the gas nozzle 8 as a clean gas, and step S4 is completed. proceed (Figure 11).

Thereafter, for example, in a state where the gas supply to the gas nozzle 8 from the first gas supply mechanism 9A and the second gas supply mechanism 9B is stopped, the IF ₇ gas is supplied from the gas shower head 7, and step S5 is performed (Fig. 13) . In addition, this step S5 can be performed using any F-based gas that can etch Si such as ClF ₃ gas and F ₂ gas. Thereafter, in the same manner as steps S2 and S4, N ₂ gas is supplied to the gas nozzle 8 from the first gas supply mechanism 9A and the second gas supply mechanism 9B, and the N ₂ gas is discharged from the gas nozzle 8 as a clean gas. S6 is performed (Fig. 11).

When performing processing by the etching module 5 in this way, the output of the pipe heater 76 and the stage heater 62 is controlled so that the temperature of the wafer W is lower than the film-forming gas ejected from the gas nozzle 8 (first film-forming gas). The temperature of the gas and the second film-forming gas may be such that the discharged film-forming gas is effectively adsorbed on the wafer W. Furthermore, the output of the pipe heater 76 and the side wall heater 54 is controlled so that the temperature of the side wall main body 53 is lower than the temperature of the film-forming gas discharged from the gas nozzle 8, so that the temperature of the side wall main body 53 collides with it. The film-forming gas can also be cooled down. In this way, through the cooling of the colliding film-forming gas, the temperature of the film-forming gas when supplied to the wafer W becomes lower, so that the film-forming gas can be adsorbed on the wafer W more effectively. In this case, in order to prevent film formation on the side wall body 53 , for example, the outputs of the stage heater 62 and the side wall heater 54 are controlled such that the temperature of the side wall body 53 > the temperature of the wafer W.

However, it is preferable that both the etching gas and the film-forming gas are supplied with high uniformity within the surface of the wafer W. The polyurea film 23 formed by the film-forming gas is removed from the wafer after the etching process as described above. Since W is removed from the sacrificial film, it is preferable that the etching gas used to form a pattern on the wafer W can be supplied with higher uniformity within the surface of the wafer W. Among the gas nozzle 8 and the gas shower head 7 , the gas shower head 7 that supplies gas in a shower shape is considered to be able to supply gas with higher uniformity within the surface of the wafer W. Therefore, the gas shower head 7 has good gas diffusivity and can supply gas with higher uniformity from each gas discharge hole 74. The flow path formed inside the gas shower head 7 tends to become narrower and has higher flexibility. That is, the gas flowing through the flow path in the gas shower head 7 suffers a large pressure loss. Therefore, the etching module 5 is configured to supply the etching gas from the gas shower head 7 in a manner that can supply the wafer W with high uniformity, and to prevent the film-forming gas from being caused by pressure loss in the flow path. It is liquefied and discharged from the gas nozzle 8.

In the etching module 5 described above, the first film-forming gas and the second film-forming gas may be ejected from different gas nozzles. Moreover, the gas nozzle 8 may be configured to have a wide discharge port along the lateral direction, for example. The exhaust port 66 is not limited to an opening at the bottom of the processing container 51 . For example, it may be an opening in a side wall below the processing container 51 . In addition, clean gas can be discharged from the gas shower head 7 . However, instead of the gas shower head 7 , a gas supply unit having gas outlets opening concentrically along the periphery of the wafer W in a plan view is provided in the ceiling portion of the processing container 51 to provide etching to the wafer W. Gas is also available. That is, the etching gas supply unit is not limited to the structure of the gas shower head 7 .

The substrate processing apparatus 3 may be configured, for example, by connecting a film forming module and an etching module each including a processing container with a vacuum atmosphere inside a transfer chamber in a vacuum atmosphere equipped with a transfer mechanism for the wafer W. In this case, the film forming module performs steps S1 to S4 respectively, and the etching module performs steps S5 and S6 respectively. The transfer mechanism between the etching module and the film forming module is provided in the transfer chamber in the vacuum atmosphere. The wafer W is repeatedly moved in between, and accordingly, the cycle consisting of steps S1 to S6 is repeated. That is, film formation and etching may be performed in mutually different processing containers. However, since the substrate processing apparatus 3 is provided with the etching module 5, when the above cycle is repeated, the moving time between modules can be saved, thereby improving productivity.

However, FIG. 14 shows an etching module 50 which is a modification of the etching module 5 . This etching module 50 will be described focusing on differences from the etching module 5 . The gas nozzle 8 is not provided in the etching module 50 . The downstream end of the gas supply pipe 81 is connected to the gas shower head 7 , and the film-forming gas is supplied to the gas diffusion space 72 . Therefore, the etching gas and the film-forming gas in the etching module 50 are supplied into the processing container 51 from the gas shower head 7 respectively. Furthermore, since the film-forming gas is discharged from the gas shower head 7 in this way, it is not necessary to provide the lower step 52 of the processing container 51 for guiding the film-forming gas discharged from the gas nozzle 8 . That is, the wall surface of the side wall of the processing container 51 does not protrude toward the mounting table 61 but is configured as a vertical surface.

In addition, the order in which the first film-forming gas containing amine, the second film-forming gas containing isocyanate, the etching gas, and the cleaning gas are supplied into the processing container 51 is not limited to the above-mentioned example. For example, the first film-forming gas and the second film-forming gas may be supplied into the processing container 51 simultaneously instead of being supplied sequentially into the processing container 51 . That is, the gases are supplied in the order of the first and second film-forming gases, the cleaning gas, the etching gas, and the cleaning gas. The supply of film-forming gas, etching gas and cleaning gas in this order is regarded as one cycle. By repeating this cycle for one wafer W, the film-forming of the polyurea film 23 and the film-forming of the polycrystalline silicon film 14 are alternately repeated. Etching is also possible. In addition, the first film-forming gas, the second film-forming gas, and the etching gas may be supplied into the processing container 51 at the same time. That is, the polyurea film 23 may be formed in the hole portion 16 of the SiOCN film 15 while the polycrystalline silicon film 14 is etched. In this case, after the first film-forming gas, the second film-forming gas, and the etching gas are supplied, the cleaning gas is supplied to purify the inside of the processing container 51 . In addition, the supply of the first film-forming gas, the second film-forming gas and the etching gas, and the subsequent supply of the cleaning gas may be regarded as one cycle, and this cycle may be repeated for one wafer W. When the etching modules 5 and 50 perform processing, signals for controlling each part of the etching modules 5 and 50 are output from the control unit 30 so as to perform such processing. The present invention is not limited to the above-mentioned embodiments, and each embodiment can be appropriately modified, and each embodiment can be combined with each other.

(Evaluation Test) Evaluation tests 1 and 2 performed in connection with the present invention will be described. As evaluation test 1, the polycrystalline silicon film 14 was removed from the wafer W having the surface portion as shown in FIG. 1 as described in the prior art project. Specifically, after the polycrystalline silicon film 14 is removed by isotropic dry etching until near the interface between the silicon oxide film 12 and the SiGe film 11, the lower polycrystalline silicon film 14 is removed by anisotropic etching, and the side walls are formed as shown in FIG. 5. The recessed portion 17 is formed by the SiOCN film 15 . Thereafter, the first film-forming gas and the second film-forming gas were supplied to the wafer W, and the polyurea film 23 with a thickness of 4 nm was formed so as to cover the surface of the wafer W including the side walls of the recessed portion 17 . Afterwards, as shown in FIG. 14 , IF ₇ gas was supplied to the wafer W, and the state of the SiGe film 11 was confirmed and no damage occurred. Therefore, it can be inferred from the test results that by filling the holes 16 of the SiOCN film 15 with the polyurea film 23 as illustrated in FIGS. 2 to 4 , the SiGe film can be protected during etching using IF ₇ gas. 11.

Next, evaluation test 2 will be described. In this evaluation test 2, a test apparatus configured to be able to supply various gases in the processing container 51 formed into a vacuum atmosphere was used in the same manner as the above-mentioned etching modules 5 and 50, and the test substrates were tested as shown in FIGS. 2 to 5. Processing of instructions. That is, after repeating the cycle of steps S1 to S6, the heat treatment of step S7 to depolymerize the polyurea film 23 is performed. The substrate for the above test had a film structure as illustrated in Fig. 1 . After the heat treatment in step S7 is performed, it is confirmed whether the polyurea film 23 remains in the hole portion 16 of the SiOCN film 15 and whether the SiGe film 11 is damaged by the etching gas. In addition, the repeated cycle of steps S1 to S6 is performed after the etching gas is supplied into the processing container 51 to etch the upper part of the polycrystalline silicon film 14 and the inside of the processing container 51 is purified.

Regarding the processing conditions in steps S1 to S4, that is, regarding the processing at the time of supply of the first film-forming gas, the time of supply of the second film-forming gas, and the time of each purification immediately after the supply of the first film-forming gas or the second film-forming gas. Conditions are explained. The pressure in the processing container 51 is set to 0.1 Torr (13.3 Pa) to 10 Torr (1333 Pa), and the temperature of the substrate is set to 0°C to 100°C. Tert-butylamine is used as the first film-forming gas, and tert-butyl isocyanate is used as the second film-forming gas. The first film-forming gas and the second film-forming gas are supplied to the processing container 51 at 20 sccm to 500 sccm respectively. As purification, N ₂ gas is supplied to the processing container 51 at 100 to 1000 sccm.

Processing conditions at the time of etching performed before the above-mentioned cycle of steps S1 to S6, etching in step S5, and each purification immediately after the etching will be described. The pressure in the processing container 51 is set to 0.1 Torr to 10 Torr, and the temperature of the substrate is set to 0°C to 100°C. ClF ₃ (chlorine trifluoride) gas is used as the etching gas. As purification, N ₂ gas is supplied into the processing container 51 at 100 to 1000 sccm. In addition, as the processing conditions during depolymerization in step S7, the pressure in the processing container 51 is set to 0.1 Torr to 10 Torr, and the temperature of the substrate is set to 100°C to 400°C. In addition, when performing this depolymerization, N ₂ gas is supplied to the processing container 51 as a clean gas at a rate of 100 sccm to 2000 sccm.

Furthermore, in the etching before the cycle of steps S1 to S6, the polycrystalline silicon film 14 is etched by 80 nm in the vertical direction, and in the etching of step S5, the polycrystalline silicon film 14 is etched by 60 nm in the vertical direction. The loop of steps S1 to S6 is performed three times. Therefore, in this evaluation test 2, the polycrystalline silicon film 14 was etched to a total thickness of 260 nm. The time for film formation and subsequent purification, that is, the time from the beginning of step S1 to the end of step S4 is set to 5 minutes. Moreover, the weight change amount before and after the treatment in this evaluation test 2 was 128 wt ppm.

The substrate after performing step S7 as described above was checked. As a result, it was confirmed that the polyurea film 23 did not remain in the hole portion 16 of the SiOCN film 15 and that there was no damage to the SiGe film 11 . Therefore, from the results of the evaluation test 2, the effect of the treatment of the present disclosure can be confirmed.

W‧‧‧wafer 11‧‧‧SiGe film 14‧‧‧Polycrystalline silicon film 15‧‧‧SiOCN film 21‧‧‧The first film-forming gas 22‧‧‧Second film-forming gas 23‧‧‧Polyurea membrane 24‧‧‧Etching gas 3‧‧‧Substrate processing equipment 30‧‧‧Control Department 5‧‧‧Film forming module 51‧‧‧Disposal container 61‧‧‧Placement table 7‧‧‧Gas sprinkler head 8‧‧‧Gas nozzle

[Fig. 1] A vertical cross-sectional side view of the surface of a wafer subjected to etching according to the present invention. [Fig. 2] A process diagram illustrating the etching process of the present invention. [Fig. 3] A process diagram illustrating the etching process of the present invention. [Fig. 4] A process diagram illustrating the etching process of the present invention. [Figure 5] A longitudinal cross-sectional side view of the wafer surface after etching. [Fig. 6] An explanatory diagram of a reaction in which a polymer having a urea bond is produced by a film-forming gas. [Fig. 7] A plan view of a substrate processing apparatus that performs etching. [Fig. 8] A longitudinal sectional side view of the etching module installed in the above substrate processing apparatus. [Fig. 9] A cross-sectional plan view of the above etching module. [Fig. 10] An explanatory diagram of the operation of the above-mentioned etching module. [Fig. 11] An explanatory diagram of the operation of the above-mentioned etching module. [Fig. 12] An explanatory diagram of the operation of the above-mentioned etching module. [Fig. 13] An explanatory diagram of the operation of the above-mentioned etching module. [Fig. 14] A longitudinal sectional side view of another structural example of an etching module. [Fig. 15] A vertical cross-sectional side view of a wafer in an evaluation test.

11‧‧‧SiGe film

12‧‧‧Silicon oxide film

14‧‧‧Polycrystalline silicon film

15‧‧‧SiOCN film

16‧‧‧hole

21‧‧‧The first film-forming gas

22‧‧‧Second film-forming gas

23‧‧‧Polyurea membrane

Claims (13)

An etching method characterized by comprising: A film-forming gas is supplied to a substrate in which a silicon-containing film, a porous film, and a non-etching target film are arranged adjacent to one another in the transverse direction, and the etching gas used to prevent etching of the silicon-containing film is passed through the pores of the porous film. A film forming process in which the passage prevention film supplied to the non-etching target film is formed in the hole portion; and An etching process in which the etching gas is supplied to etch the silicon-containing film. For example, the etching method in item 1 of the patent scope applied for, among which It includes a repetitive process of sequentially repeating the above-mentioned film forming process and the above-mentioned etching process a plurality of times. For example, the etching method in item 2 of the patent scope applied for, among which The above-mentioned film-forming gas includes a first film-forming gas and a second film-forming gas, The film-forming process includes sequentially supplying the first film-forming gas and the second film-forming gas to the substrate, causing the first film-forming gas and the second film-forming gas to react with each other to form the passage prevention film. project. For example, the etching method in item 3 of the patent application scope, among which Including: between the period when the above-mentioned first film-forming gas is supplied and the period when the above-mentioned second film-forming gas is supplied, between the period when the above-mentioned second film-forming gas is supplied and the period when the above-mentioned etching gas is supplied, the above-mentioned etching gas is supplied. Between the period of supplying the first film-forming gas and the period of supplying the first film-forming gas, an exhaust process is performed around the substrate. For example, the etching method in item 1 of the patent scope applied for, among which The etching gas is supplied to the substrate and the film-forming gas is supplied to the substrate simultaneously. If the etching method of any one of items 1 to 5 of the patent scope is applied for, among which It includes a heating process of heating the substrate in order to vaporize and remove the passage prevention film from the hole portion after performing the film forming process and the etching process. If the etching method of any one of items 1 to 5 of the patent scope is applied for, among which An etching mask film is formed on the upper side of the non-etching target film. If the etching method of any one of items 1 to 5 of the patent scope is applied for, among which The above-mentioned anti-passing film is a polymer having urea bonds. An etching device, characterized by comprising: processing containers; A placement portion is provided in the above-mentioned processing container and is used for placing a substrate in which the silicon-containing film, the porous film, and the non-etching target film are arranged adjacent to each other in the transverse direction; The film-forming gas supply unit is configured to provide a pass-prevention film on the processing container in order to prevent the etching gas from etching the silicon-containing film from being supplied to the non-etching target film through the hole portion of the porous film. Film-forming gas is supplied internally; and The etching gas supply unit supplies the etching gas into the processing container. For example, the etching device in item 9 of the patent scope applied for, among which A control unit is provided that outputs a control signal so as to sequentially repeat the supply of the film-forming gas and the supply of the etching gas a plurality of times. For example, the etching device in item 9 of the patent scope applied for, among which A control unit is provided that outputs a control signal so that the etching gas is supplied to the substrate and the film-forming gas is supplied to the substrate simultaneously. If the etching device is applied for any one of items 9 to 11 of the patent scope, among which The etching gas supply part is a shower head provided to face the mounting part. If the etching device is applied for any one of items 9 to 11 of the patent scope, among which The film-forming gas supply unit is provided so that the film-forming gas supplied from the film-forming gas supply unit collides with the side wall of the processing container before the film-forming gas is supplied to the substrate.