JP7067424B2 - Etching method and etching equipment - Google Patents

Description

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

The interlayer insulating film in which the wiring constituting the semiconductor device is embedded may be formed of a low dielectric constant film called a low-k film, and the low-k film is formed of, for example, a porous film. Then, in the manufacturing process of the semiconductor device, etching may be performed on a semiconductor wafer (hereinafter, referred to as a wafer) on which such a porous film is formed.

For example, Patent Document 1 describes that a wafer on which an interlayer insulating film, which is a low-k film, is formed is etched to form a recess for embedding wiring. A film is formed in the recess to prevent the film from being exposed to the atmosphere until the wiring is embedded in the recess by supplying the film-forming gas. Further, in Patent Document 2, a technique for etching an organic film embedded in a recess formed in a low dielectric constant film, which is a porous film, by using plasma of a processing gas containing a predetermined amount of carbon dioxide. Have been described.

Japanese Unexamined Patent Publication No. 2016-63141 Japanese Patent No. 4940722

In manufacturing a semiconductor device, a polysilicon film, a SiOCN film which is a porous film, and a laminate formed by a silicon oxide film on the upper side and a SiGe (silicon germanium) film on the lower side are arranged in this order in the horizontal direction. A process for removing the polysilicon film may be performed on the wafers formed on the surface portions of the wafers so as to be adjacent to each other. If the polysilicon film removal process is performed by dry etching, the etching gas permeates the SiOCN film and is supplied to the SiGe film in the process of etching the polysilicon film. More specifically, since the SiOCN film is a porous film, the etching gas passes through the pores of the porous film from the side of the SiOCN film and is supplied to the side wall of the SiGe film. The SiGe film is not a target to be removed by etching, but the side wall thereof is etched by supplying the etching gas in this way.

Therefore, for example, after removing the upper side of the polysilicon film by anisotropic etching using plasma, a process may be performed so as to remove the lower side of the polysilicon film by wet etching. Since the etching solution used for this wet etching has a lower permeability of the SiOCN film than the above-mentioned etching gas, the etching of the SiGe film is suppressed. However, it is troublesome to perform a plurality of steps in this way, and even in the wet etching step, the treatment becomes impossible due to the miniaturization of the apparatus, and the thickness of the side wall of the SiOCN film tends to be small. If the thickness of the side wall of the SiOCN film becomes smaller in the future, the permeability of the etching solution to the SiOCN film may increase, and the SiGe film may be etched. The techniques described in the above-mentioned Patent Documents 1 and 2 cannot solve such a problem.

The present invention has been made based on such circumstances, and an object thereof is to supply an etching gas to a substrate in which a silicon-containing film, a porous film, and an etching non-target film are provided adjacent to each other in this order in the lateral direction. It is an object of the present invention to provide a technique capable of preventing an etching non-target film from being etched when removing a silicon-containing film (including a case where the film itself is silicon).

In the etching method of the present invention, a film-forming gas is supplied to a substrate in which a silicon-containing film, a porous film, and an etching non-target film are provided adjacent to each other in this order in the horizontal direction, and an etching gas for etching the silicon-containing film. A film forming step of forming a passage prevention film in the pores to prevent the film from passing through the pores of the porous film and being supplied to the etching non-target film.
An etching step of supplying the etching gas to etch the silicon-containing film,
It is characterized by including.

The etching apparatus of the present invention includes a processing container and
A mounting portion for mounting a substrate provided in the processing container in which a silicon-containing film, a porous film, and an etching non-target film are provided adjacent to each other in this order in the lateral direction.
The process for forming an anti-passage film in the pores to prevent the etching gas for etching the silicon-containing film from passing through the pores of the porous film and being supplied to the non-etching film. A film forming gas supply unit that supplies the film forming gas into the container, and
An etching gas supply unit that supplies the etching gas into the processing container,
It is characterized by including.

According to the present invention, a film-forming gas is supplied to a substrate in which a silicon-containing film, a porous film, and an etching non-target film are provided adjacent to each other in this order in the lateral direction, and the silicon-containing film is etched in the pores of the porous film. An anti-passage film is formed to prevent the etching gas to be supplied to the non-etching film. As a result, when etching the silicon-containing film, the etching of the non-etching film is suppressed.

It is a vertical sectional side view of the surface of the wafer which performs the etching which concerns on this invention. It is a process drawing explaining the etching process which concerns on this invention. It is a process drawing explaining the etching process which concerns on this invention. It is a process drawing explaining the etching process which concerns on this invention. It is a vertical sectional side view of the surface of a wafer after etching completion. It is explanatory drawing which shows the reaction which the polymer having a urea bond is generated by the film formation gas. It is a top view of the substrate processing apparatus for performing etching. It is a vertical sectional side view of the etching module provided in the substrate processing apparatus. It is a cross-sectional plan view of the etching module. It is explanatory drawing which shows the operation of the etching module. It is explanatory drawing which shows the operation of the etching module. It is explanatory drawing which shows the operation of the etching module. It is explanatory drawing which shows the operation of the etching module. It is a vertical sectional side view which shows the structural example of another etching module. It is a vertical sectional side view of a wafer in an evaluation test.

FIG. 1 shows a vertical sectional side view of a surface portion of a wafer W on which a process according to an embodiment of the present invention is performed. In the figure, 11 is a SiGe 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 SiOCN film 15, and the 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 and is a porous film.

The outline of the treatment in the embodiment of the present invention will be described by supplying a film forming gas for forming a polyurea film which is a polymer (polyurea) having a urea bond in the pores of the SiOCN film 15 and a coating film. The supply of the etching gas for etching the polysilicon film 14 which is the etching film is alternately repeated. That is, the polysilicon film 14 is etched at intervals, and a polyurea film is formed between the etchings so as to be embedded in the pores. This prevents the etching gas from penetrating the SiOCN film 15 from the side of the SiOCN film 15 and etching the side wall of the SiGe film 11 which is an etching non-target film.

The silicon oxide film 12 is an etching mask film for etching the polysilicon film 14. Further, as the etching gas, for example, IF ₇ (iodine heptafluoride) is used because the etching selectivity for the silicon oxide film 12 and the polyurea film is low and the etching selectivity for the polysilicon film 14 is high. ) Gas is used. Since this IF ₇ gas has a relatively large molecular weight, it is considered that it is difficult to pass through the pores of the SiOCN film 15, and it is also preferable from the viewpoint that the supply to the SiGe film 11 is expected to be suppressed more reliably.

In this embodiment, the above-mentioned polyurea film is formed by supplying a first film-forming gas containing amine as a monomer and a second film-forming gas containing isocyanate as a monomer to the wafer W for polymerization reaction. do. As the amine, for example, 1,3-bis (aminomethyl) cyclohexane (H6XDA) is used, and as the isocyanate, for example, 1,3-bis (isocyanatemethyl) cyclohexane (H6XDI) is used. Further, hexylamine may be used as the amine and tert-butylisocyanic acid may be used as the isocyanate. The amine and isocyanate capable of forming a polyurea film are not limited to this example, and further specific examples will be given later.

Subsequently, the processing performed on the wafer W will be described with reference to FIGS. 2 to 4. 2 to 4 are schematic views showing how the surface portion of the wafer W described with reference to FIG. 1 changes depending on the treatment. In the figure, the pores formed in the SiOCN film 15 are 16, the first film-forming gas which is an amine is 21, the second film-forming gas which is isocyanate is 22, the polyurea film is 23, and IF ₇ . The etching gas is represented as 24. Further, each process shown in FIGS. 2 to 4 is performed in a state where the wafer W is carried into the processing container, the inside of the processing container is exhausted, and a vacuum atmosphere having a predetermined pressure is created.

First, the first film-forming gas 21 is supplied into the processing container (step S1, FIG. 2A). The first film-forming gas 21 flows into the hole 16 on the upper side of the SiOCN film 15 and is adsorbed on the hole wall. Subsequently, the supply of the first film-forming gas 21 into the processing container is stopped, and the exhaust gas and, for example, the purge gas, which is _N2 (nitrogen) gas, are supplied in the processing container (step S2, FIG. 2B), the first film-forming gas 21 that did not flow into the hole 16 is removed by the air flow of the exhausted purge gas.

Subsequently, the second film-forming gas 22 is supplied into the processing container (step S3, FIG. 2C), and the second film-forming gas 22 flows into the hole 16 on the upper side of the SiOCN film 15. Then, it reacts with the first film-forming gas 21 adsorbed on the pore portion 16 to form a polyurea film 23 which is a film for preventing the passage of the etching gas, and the pore portion 16 is closed. After that, the supply of the second film-forming gas 22 into the processing container is stopped, and the exhaust gas and the purge gas are supplied in the processing container (step S4, FIG. 2D). The second film-forming gas 22 that did not flow into the portion 16 is removed by the air flow of the exhausted purge gas.

Subsequently, the etching gas 24 is supplied into the processing container (step S5, FIG. 3 (e)), the polysilicon film 14 is etched, and the side wall on the upper side of the SiOCN film 15 is exposed. At this time, the polyurea film 23 is embedded in the hole 16 on the upper side of the SiOCN film 15, and the polyurea film 23 is difficult to be etched by the etching gas 24. Therefore, since the passage of the hole 16 of the etching gas 24 is prevented, it is possible to prevent the etching gas 24 from penetrating the SiOCN film 15 from the side and etching the side wall of the SiGe film 11. After that, the supply of the etching gas 24 into the processing container is stopped, the exhaust gas and the purge gas are supplied in the processing container (step S6, FIG. 3 (f)), and the etching remaining in the processing container is performed. The gas 24 is removed by riding on the air flow of the purge gas exhausted from the processing container.

After that, the first film-forming gas 21 is supplied into the processing container. That is, step S1 is executed again. Since the polysilicon film 14 is etched in step S5 to expose the upper side wall of the SiOCN film 15, the first film-forming gas 21 supplied in the second step S1 is the SiOCN film 15. In the first step S1, the first film-forming gas 21 is supplied to the hole 16 below the hole 16 to which the first film-forming gas 21 is supplied and is adsorbed on the hole wall.

After that, the exhaust gas and the purge gas are supplied again in the processing container of step S2, and then the second film-forming gas 22 is supplied again into the processing container of step S3. As for the second film-forming gas 22, the second film-forming gas 22 is supplied in the first step S3 as well as the first film-forming gas 21 supplied into the processing container in the second step S1. The polyurea film 23 is formed by being supplied to the pores 16 below the pores 16 of the SiOCN film 15 and reacting with the first film-forming gas 21 adsorbed in the pores 16. .. Therefore, in this second step S3, the region where the polyurea film 23 is formed in the SiOCN film 15 expands downward (FIG. 4A).

After that, after the exhaust gas and the purge gas of step S4 are supplied, the etching gas 24 of step S5 is supplied, and the polysilicon film 14 is further etched downward and exposed on the side wall of the SiOCN film 15. The area to be etched expands downward. As described above, the region where the polyurea film 23 is formed in the SiOCN film 15 is expanded downward by the second step S3, so that the side wall of the SiOCN film 15 newly exposed by the etching of the polysilicon film 14 The hole 16 in the vicinity is in a state in which the polyurea film 23 is embedded. Therefore, even in this second step S5, it is possible to prevent the etching gas from passing through the pore portion 16 of the SiOCN film 15 and etching the side wall of the SiGe film 11 (FIG. 4B). After this etching, the exhaust gas and the purge gas supply in step S6 are performed again.

Assuming that steps S1 to S6 performed in this order are one cycle, for example, even after the second step S6 is performed, the cycle is repeated and the SiOCN film 15 is directed downward. The polyurea film 23 to be filmed prevents etching of the side wall of the SiGe film 11, while the polysilicon film 14 is etched downward. Then, for example, when all the polysilicon film 14 is etched and a predetermined number of cycles are completed (FIG. 4 (c)), the wafer W is heated to, for example, 100 ° C. or higher, preferably 300 ° C. or higher, so that the pores are formed. The polyurea film 23 embedded in 16 is vaporized or depolymerized and vaporized, and is removed from the wafer W (FIG. 4 (d)). The etching residue adhering to the surface of the wafer W is also vaporized and removed together with the polyurea film 23 by this heating (step S7). FIG. 5 shows a wafer W from which the polysilicon film 14 is etched and the polyurea film 23 is removed. 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.

According to the process of the embodiment of the above invention, the polysilicon film 14 can be etched by the etching gas while suppressing the SiGe film 11 from being etched by the etching gas. Further, in the treatment of the embodiment of the present invention, as compared with the case of performing the treatment using wet etching after the plasma treatment described in the background technique, the atmosphere around the wafer W is wet-etched from the vacuum atmosphere for performing the plasma treatment. There is no need to switch to the atmospheric atmosphere to do. Therefore, the processing of the embodiment of the present invention has an advantage that the time and labor required for the processing can be reduced. Further, according to the process of the embodiment, since it is not necessary to use plasma, each film on the surface of the wafer W is not damaged by the plasma, so that the reliability of the semiconductor device formed from the wafer W can be improved. There is also the advantage that it can be made higher. However, the case where etching is performed using plasma is also included in the scope of rights of the present invention.

The exhaust flow rate of the processing container may be constant in steps S1 to S6 described above, and the exhaust gas flow rate in steps S2, S4, and S6 for removing unnecessary gas in the processing container is more reliably removed. It may be larger than the exhaust flow rate of steps S1, S3, and S5 so as to be able to do so. Further, in steps S2, S4, and S6, the purge gas may not be supplied and unnecessary gas may be removed only by exhaust gas. As described above, the etching selectivity of the IF ₇ gas, which is an etching gas, for the polyurea film 23 is relatively low. Therefore, when the polyurea film 23 is formed on the surface of the polysilicon film 14, the polysilicon film 14 is formed. Will be difficult to etch. However, the unnecessary first film-forming gas 21 and the second film-forming gas 22 are removed in the above-mentioned steps S2 and S4. That is, by performing steps S2 and S4, etching of the polysilicon film 14 can be performed more reliably.

By the way, a silicon-containing film other than the polysilicon film 14 may be a film to be etched. This silicon-containing film is a film containing silicon as a main component, and specifically, for example, an amorphous silicon film, a single crystal silicon film, a SiGe film, or the like is included in the silicon-containing film. The etching gas may be any gas that can etch the silicon-containing film. Specifically, the etching gas includes, for example, fluorine (F ₂ ) gas, ClF ₃ (chlorine trifluoride), IF ₅ (iodine trifluoride) gas, BrF ₃ (bromine trifluoride), etc., in addition to IF ₇ gas. A gas containing fluorine can be used.

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, 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.

Further, the film forming gas for forming the polyurea film 23 is not limited to the above example. For example, 1,12-diaminododecane (DAD) may be used as an amine, 4,4'-diphenylmethane diisocyanate (MDI) may be used as an isocyanate, DAD may be used as an amine, and H6XDI may be used as an isocyanate, or an amine may be used. Hexamethylenediamine may be used as the isocyanate, and H6XDI may be used as the isocyanate. By the way, as the amine, for example, 1,6-diaminohexane, cyclohexylamine, hexylamine, butylamine and tert-butylamine can be used in addition to the above-mentioned compounds. As the isocyanate, for example, hexane 1,6-diisocyanate, cyclohexylisocyanic acid, hexylisocyanic acid, butylisocyanic acid, and tertbutylisocyanic acid can be used in addition to the above-mentioned compounds. That is, one selected from the above-mentioned amine compounds and one selected from the above-mentioned isocyanate compounds can be used for forming the polyurea film 23, respectively. To further explain the variation of the reaction between isocyanate and amine, as shown in FIG. 6, a monofunctional molecule may be used as the raw material monomer constituting the film-forming gas in the reaction. Further, the gas generated by heating and depolymerizing the polyurea to vaporize it is supplied to the wafer W as a film forming gas, and the gas is cooled and adsorbed on the surface of the wafer W to cause a polymerization reaction, and the polyurea is again poly. A urea film may be formed. Therefore, the film forming gas is not limited to supplying the first film forming gas and the second film forming gas to the wafer W.

In the processing example described with reference to FIGS. 2 to 4, it is described that steps S1 to S6 are performed three or more times, but steps S1 to S6 may be performed only twice. Further, in step S7, the wafer W is heated so that the polyurea film 23 is removed from the SiOCN film 15, but even if the polyurea film 23 remains in the pores 16 of the SiOCN film 15, the SiOCN film 15 If there is no practical problem in the dielectric constant, it is conceivable that the polyurea membrane 23 may remain as such. Therefore, even if the polyurea membrane 23 in step S7 is not removed, it is included in the scope of rights of the present invention.

Subsequently, the substrate processing apparatus 3 for performing the series of processing described with reference to FIGS. 2 to 4 will be described with reference to the plan view of FIG. 7. 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. In the figure, 36 is an oriental chamber adjacent to the normal pressure transport chamber 33, which is provided to rotate the wafer W to optically determine the amount of eccentricity and to align the wafer W with respect to the first substrate transport 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 puts the wafer W in 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 constituting the etching module 5 are configured as a vacuum atmosphere, and the inside of the load lock chamber 41 includes the inside of the processing container having these vacuum atmospheres 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. The heat treatment module 40 includes 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. Including, it is configured so that the above-mentioned step S7 can be executed.

Subsequently, the etching module 5 will be described with reference to the vertical sectional side view of FIG. 8 and the sectional plan view of FIG. The etching module 5 includes, for example, a circular processing container 51, and the wafers W are processed in steps S1 to S6 in the processing container 51. That is, etching and film formation are performed in the common processing container 51. The processing container 51 is an airtight vacuum container, and a circular mounting table 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. 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 S6 can be performed. In the figure, 63 is 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 three vertical elevating pins, and the surface of the mounting table 61 is recessed by the elevating mechanism 65, and the wafer W is transferred between the above-mentioned second substrate transport mechanism 42 and the mounting table 61. conduct.

The lower side of the side wall of the processing container 51 projects toward the center side of the processing container 51 when viewed in a plane, and is close to the side portion of the mounting table 61 to form a ring-shaped lower portion 52 in a plan view. The upper surface of the lower portion 52 is horizontal and is formed at the same height as the surface of the mounting table 61, for example. In the side wall of the processing container 51, the upper side of the lower portion 52 is referred to as the side wall main body portion 53. As will be described later, the film-forming gas (the first film-forming gas and the second film-forming gas) is discharged so as to collide with the side wall main body 53 forming the collided member, and the lower portion 52 is thus discharged. It has a role as a guide member for supplying the discharged film-forming gas to the mounting table 61 along the upper surface thereof. Reference numeral 54 in the figure is a side wall heater, which is embedded in the lower portion 52 and the side wall main body 53, respectively. The side wall heater 54 adjusts the temperature of the surface of the lower stage portion 52 and the side wall main body 53 inside the processing container 51, and the temperature of the film-forming gas colliding with the side wall main body 53 and the atmosphere inside the processing container 51. The temperature is adjusted.

Reference numeral 55 in FIG. 9 is a transfer port for the wafer W, which is opened at a portion of the side wall main body 53 that is separated from the portion where the film-forming gas collides in the circumferential direction of the processing container 51, and is opened and closed by the gate valve 43. It is freely configured. In the figure, reference numeral 66 denotes an exhaust port opened to the bottom surface of the processing container 51, which is connected to an exhaust mechanism 67 (see FIG. 8) composed of a vacuum pump, a valve, and the like via an exhaust pipe. By adjusting the exhaust flow rate from the exhaust port 66 by the exhaust mechanism 67, 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 forming an etching 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 the 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 diffuser plate 73, and a large number of holes are dispersed and perforated in the diffuser plate 73. In the figure, 77 is a ceiling 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 unit 69. The flow rate adjusting unit 69 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 68. Each flow rate adjusting unit, which will be described later, has the same configuration as the flow rate adjusting unit 69, and adjusts the flow rate of the gas supplied to the downstream side of the pipe through which the flow rate adjusting unit is interposed.

The side wall main body 53 of the processing container 51 is provided with a gas nozzle 8 which is a film-forming gas supply unit for supplying the film-forming gas (first film-forming gas and second film-forming gas). .. That is, the film-forming gas is supplied from a gas supply unit provided separately from the gas shower head 7. Further, the gas nozzle 8 supplies the above-mentioned purge gas in addition to the film-forming gas.

The gas nozzle 8 is formed in a rod shape extending in the lateral direction, for example. The arrow of the chain line in FIGS. 8 and 9 indicates the opening direction of the discharge port provided at the tip of the gas nozzle 8, that is, the gas discharge direction. As these arrows indicate, the gas nozzle 8 discharges gas horizontally along the diameter of the wafer W. Since the side wall main body 53 is located ahead of the gas discharge direction, the discharged gas collides with the side wall main body 53 before being supplied to the wafer W. That is, the gas discharge port provided in the gas nozzle 8 is not directed toward the wafer W, but is directed toward the side wall main body 53 which is a collided member. Then, the gas that collides with the side wall main body 53 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.

The gas nozzle 8 is configured in this way as compared with the case where the discharge port of the gas nozzle 8 is directed to the wafer W and the discharged gas is directly supplied to the wafer W. The purpose is that the gas discharged before reaching W travels a long distance to sufficiently diffuse the gas in the lateral direction. That is, the gas nozzle 8 is configured to discharge the gas toward the side wall main body 53 so that each gas is supplied to the surface of the wafer W with high uniformity.

81 in FIG. 8 is a gas supply pipe, which is connected to the gas nozzle 8 from the outside of the processing container 51. The upstream side of the gas supply pipe 81 is branched to form the gas introduction pipes 82 and 83. The upstream side of the gas introduction pipe 82 is connected to the vaporization unit 92 via the flow rate adjusting unit 91 and the valve V1 in this order. In the vaporization unit 92, the above-mentioned H6XDA is stored in a liquid state, and the vaporization unit 92 includes a heater (not shown) for heating the H6XDA. Further, one end of the gas supply pipe 94 is connected to the vaporization unit 92, and the other end of the gas supply pipe 94 is connected to the _N2 (nitrogen) gas supply source 96 via the valve V2 and the gas heating unit 95 in this order. Has been done. With such a configuration, the heated N ₂ gas is supplied to the vaporization unit 92 to vaporize the H6XDA in the vaporization unit 92, and the mixed gas of the N ₂ gas and the H6XDA gas used for the vaporization is the first gas. As the film-forming gas of the above, it is introduced into the gas nozzle 8.

Further, regarding the gas supply pipe 94, a portion on the downstream side of the gas heating unit 95 and an upstream side of the valve V2 branches to form a gas supply pipe 97, and the end portion of the gas supply pipe 97 is interposed via the valve V3. It is connected to the downstream side of the valve V1 of the gas introduction pipe 82 and the upstream side of the flow rate adjusting unit 91. Therefore, when the first film-forming gas is not supplied to the gas nozzle 8, the _N2 gas heated by the gas heating unit 95 can be introduced into the gas nozzle 8 by bypassing the vaporization unit 92.

Further, the upstream side of the gas introduction pipe 83 is connected to the vaporization unit 102 via the flow rate adjusting unit 101 and the valve V4 in this order. In the vaporization unit 102, the above-mentioned H6XDI is stored in a liquid state, and the vaporization unit 102 includes a heater (not shown) for heating the H6XDI. Further, one end of the gas supply pipe 104 is connected to the vaporization unit 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 unit 105 in this order. Has been done. With such a configuration, the heated N ₂ gas is supplied to the vaporization unit 102 to vaporize the H6XDI in the vaporization unit 102, and the mixed gas of the N ₂ gas and the H6XDI gas used for the vaporization is the second gas. As the film-forming gas of the above, it is introduced into the gas nozzle 8.

Further, regarding the gas supply pipe 104, a portion on the downstream side of the gas heating unit 105 and on the upstream side of the valve V5 branches to form the gas supply pipe 107, and the end portion of the gas supply pipe 107 passes through the valve V6. , It is connected to the downstream side of the valve V4 of the gas introduction pipe 83 and the upstream side of the flow rate adjusting unit 101. Therefore, when the above-mentioned second film-forming gas is not supplied to the gas nozzle 8, the N2 gas heated by the gas heating unit 105 can be introduced into the gas nozzle 8 by bypassing the vaporization unit 102.

In order to prevent H6XDA and H6XDI in the film-forming gas in circulation from liquefying in 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 the pipe. Be done. The temperature of the film-forming gas discharged from the gas nozzle 8 is adjusted by the piping heater 76, the gas heating units 95 and 105, and the heaters provided in the vaporization units 92 and 102. For convenience of illustration, the pipe heater 76 is shown only in a part of the gas supply pipe 81 and the gas introduction pipes 82 and 83, but it is covered in a relatively wide range of these pipes so as to prevent the above liquefaction. It will be provided across.

The first gas is supplied to the upstream side of the flow rate adjusting unit 91 in the gas introduction pipe 82, the flow rate adjusting unit 91, the vaporization unit 92, the valves V1 to V3, the gas supply pipes 94 and 97, the gas heating unit 95 and the N2 gas supply source 96. The mechanism is 9A. Further, the upstream side of the flow rate adjusting unit 101 in the gas introduction pipe 83, the flow rate adjusting unit 101, the vaporization unit 102, the valves V4 to V6, the gas supply pipes 104 and 107, the gas heating unit 105 and the _N2 gas supply source 106 are 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 is the N ₂ gas or the second formation gas. Membrane gas can be supplied to the gas nozzle 8.

By the way, as shown in FIG. 7, the board processing apparatus 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 operation of the etching module 5 is as follows: adjustment of the output of each heater, first gas supply mechanism 9A, second gas supply mechanism 9B, supply / interruption of IF 7 gas from the gas shower head 7, and supply / discontinuance of IF ₇ gas from the gas nozzle 8. Each operation such as supply / disconnection of each gas, adjustment of the exhaust flow rate by the exhaust mechanism 67, and raising / lowering of the raising / lowering pin 64 by the raising / lowering mechanism 65 is included. The control unit 30 and the etching module 5 correspond to the etching apparatus of the present invention.

The transfer path of the wafer W in the substrate processing apparatus 3 will be described. As described with reference to FIG. 1, the carrier 34 containing the wafer W on which each film is formed is placed on the 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 S6 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 S7. After that, the wafer W is conveyed in the order of the load lock chamber 41 → the normal pressure transfer chamber 33, and is returned to the carrier 34.

Subsequently, regarding the correspondence between the above steps S1 to S6 performed in the etching module 5 and the gas supplied from the first gas supply mechanism 9A and the second gas supply mechanism 9B provided in the etching module 5. This will be described with reference to FIGS. 10 to 13. A first film-forming gas is supplied from the first gas supply mechanism 9A and an _N2 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 to step up. S1 is performed (FIG. 10). Subsequently, N _{2 gas is supplied to the gas nozzle 8 from the first gas supply mechanism 9A and the second gas supply mechanism 9B, respectively, and this N 2 gas} is discharged from the gas nozzle 8 as purge gas, and step S2 is performed (. FIG. 11). After that, the N ₂ gas is supplied from the first gas supply mechanism 9A to the gas nozzle 8 from the second gas supply mechanism 9B, and the mixed gas thereof is discharged from the gas nozzle 8. , Step S3 is performed (FIG. 12). After that, as in step S2, N2 gas is supplied to the gas nozzle 8 from the first gas supply mechanism 9A and the second gas supply mechanism 9B, respectively, and this _N2 gas is discharged from the gas nozzle 8 as purge gas. Step S4 is performed (FIG. 11).

After that, for example, with the gas supply from the first gas supply mechanism 9A and the second gas supply mechanism 9B stopped to the gas nozzle 8, IF ₇ gas is supplied from the gas shower head 7 and step S5 is performed (. FIG. 13). It should be noted that this step S5 can be performed by using any of the F-based gases such as the ClF ₃ gas and the F ₂ gas described above that can etch Si. After that, as in 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, respectively, and this N 2 gas} is discharged from the gas nozzle 8 as purge gas. Then, step S6 is performed (FIG. 11).

When the processing by the etching module 5 is performed in this way, the temperature of the wafer W is adjusted to the film forming gas discharged from the gas nozzle 8 (first film forming gas) by controlling the outputs of the piping heater 76 and the stage heater 62. The temperature may be lower than the temperature of the second film-forming gas) so that the discharged film-forming gas is efficiently adsorbed on the wafer W. Further, the output of the piping 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, and the film forming collides with the side wall main body 53. The temperature of the gas may be lowered. By lowering the temperature of the film-forming gas that collides in this way, the temperature of the film-forming gas becomes relatively low when it is supplied to the wafer W, and the film-forming gas can be more efficiently adsorbed on the wafer W. In that case, in order to prevent the film from being formed on the side wall main body 53, the outputs of the stage heater 62 and the side wall heater 54 are controlled so that, for example, the temperature of the side wall main body 53> the temperature of the wafer W.

By the way, it is desirable to supply both the etching gas and the film forming gas with high uniformity in the plane of the wafer W, but the polyurea film 23 formed by the film forming gas is formed from the wafer W after the etching process as described above. Since it is a sacrificial film to be removed, it is preferable to supply the etching gas for forming a pattern on the wafer W with higher uniformity in the plane of the wafer W. In the gas nozzle 8 and the gas shower head 7, it is expected that the gas shower head 7 that supplies gas in a shower shape can supply gas more uniformly in the plane of the wafer W. The gas shower head 7 has a good gas diffusivity, and the flow path formed inside tends to be narrow and highly flexible so that the gas can be uniformly supplied from each gas discharge hole 74. There is. That is, the gas flowing through the flow path in the gas shower head 7 receives a relatively large pressure loss. Therefore, the etching module 5 supplies the etching gas from the gas shower head 7 so as to be supplied to the wafer W with high uniformity, and the film-forming gas is to prevent liquefaction due to pressure loss in the flow path. It is configured to discharge 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 discharged from separate gas nozzles. Further, the gas nozzle 8 may be configured to have, for example, a wide discharge port in the lateral direction. The exhaust port 66 is not limited to opening at the bottom of the processing container 51, and may be opened at, for example, the lower side wall of the processing container 51. Further, the purge gas may be discharged from the gas shower head 7. By the way, in the ceiling portion of the processing container 51, instead of the gas shower head 7, for example, a gas supply unit having a gas discharge port opened concentrically along the circumference of the plan-view wafer W is provided to supply etching gas to the wafer W. May be supplied. That is, the etching gas supply unit is not limited to being configured as the gas shower head 7.

Further, the substrate processing apparatus 3 is configured by connecting, for example, a film forming module and an etching module having a processing container for forming a vacuum atmosphere inside to a vacuum atmosphere transport chamber equipped with a wafer W transport mechanism. You may. In that case, the film forming module is configured to be able to perform steps S1 to S4, and the etching module is configured to be able to perform steps S5 and S6, respectively. By repeatedly moving the wafer W in, the cycle consisting of steps S1 to S6 is repeatedly performed. That is, the film formation and the etching may be performed in different processing containers. However, since the substrate processing apparatus 3 includes the etching module 5 described above, it is possible to save time for moving between such modules when repeating the cycle described above, so that the throughput can be improved.

By the way, FIG. 14 shows an etching module 50 which is a modification of the etching module 5. The etching module 50 will be described focusing on the differences from the etching module 5. The etching module 50 is not provided with a gas nozzle 8, and 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, in the etching module 50, the etching gas and the film-forming gas are each supplied from the gas shower head 7 into the processing container 51. Since the film-forming gas is discharged from the gas shower head 7 in this way, the lower portion 52 of the processing container 51 for guiding the film-forming gas discharged from the gas nozzle 8 may not be provided. That is, the wall surface of the side wall of the processing container 51 may be configured as a vertical surface without protruding toward the mounting table 61.

Further, the order of supplying the first film-forming gas containing amine, the second film-forming gas containing isocyanate, the etching gas and the purge gas 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 can be simultaneously supplied into the processing container 51 instead of being sequentially supplied into the processing container 51. That is, the gas is supplied in the order of the first and second film forming gas, the purge gas, the etching gas, and the purge gas. Then, the film formation gas, the etching gas, and the purge gas are supplied in this order as one cycle, and by repeating this cycle for one wafer W, the film formation of the polyurea film 23 and the polysilicon film 14 are performed. Etching may be repeated alternately. Further, 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 polysilicon film 14 may be etched while the polyurea film 23 is formed in the pores 16 of the SiOCN film 15. In that case, after supplying the first film-forming gas, the second film-forming gas, and the etching gas, a purge gas is supplied to purge the inside of the processing container 51. The supply of the first film-forming gas, the second film-forming gas and the etching gas and the subsequent supply of the purge gas are regarded as one cycle, and this cycle is repeated for one wafer W for processing. You may. When processing is performed by the etching modules 5 and 50, a control signal is output from the control unit 30 to each unit of the etching modules 5 and 50 so that such processing is performed.
The present invention is not limited to the above-described embodiments, and the embodiments can be appropriately modified, and the embodiments can be combined with each other.

(Evaluation test)
The evaluation tests 1 and 2 conducted in connection with the present invention will be described. As the evaluation test 1, the wafer W whose surface portion was configured as shown in FIG. 1 was subjected to a treatment for removing the polysilicon film 14 as described in the item of background art. More specifically, after removing the polysilicon film 14 by isotropic dry etching to near the interface between the silicon oxide film 12 and the SiGe film 11, the lower polysilicon film 14 is removed by anisotropic etching, and FIG. 5 shows. As shown, a recess 17 having a side wall formed of a SiOCN film 15 was formed. After that, the first film-forming gas and the second film-forming gas are supplied to the wafer W to form a polyurea film 23 having a thickness of 4 nm so as to cover the surface of the wafer W including the side wall of the recess 17. Membrane. After that, as shown in FIG. 14, after supplying IF ₇ gas to the wafer W, the state of the SiGe film 11 was confirmed, but no damage occurred. Therefore, from this test result, the SiGe film 11 is protected from etching by IF ₇ gas by forming the polyurea film 23 so as to be embedded in the pores 16 of the SiOCN film 15 as described with reference to FIGS. 2 to 4. It is thought that it can be done.

Subsequently, the evaluation test 2 will be described. In this evaluation test 2, a test device configured to be able to supply various gases into the processing container 51 in which a vacuum atmosphere is formed similar to the etching modules 5 and 50 described above is used for the test substrate. The processing described with reference to FIGS. 2 to 5 was performed. That is, after repeating the cycles of steps S1 to S6, a heat treatment for depolymerizing the polyurea membrane 23 of step S7 was performed. The test substrate described above has the membrane structure described in FIG. Then, after the heat treatment in step S7, it is confirmed whether or not the polyurea film 23 remains in the pores 16 of the SiOCN film 15, and whether or not the SiGe film 11 is damaged by the etching gas. Confirmation was done. The cycle of repeating steps S1 to S6 is performed after supplying an etching gas into the processing container 51 to etch the upper portion of the polysilicon film 14 and purging the inside of the processing container 51.

The processing conditions in steps S1 to S4, that is, the processing conditions at the time of supplying the first film forming gas, at the time of supplying the second film forming gas, and at the time of each purging immediately after supplying the first film forming gas or the second film forming gas. Will be described. The pressure in the processing container 51 was 0.1 Torr (13.3 Pa) to 10 Torr (1333 Pa), and the temperature of the substrate was 0 ° C to 100 ° C. Then, tert-butylamine is used as the first film-forming gas, and tert-butylisocyanic acid is used as the second film-forming gas, and the first film-forming gas and the second film-forming gas are each treated at 20 sccm to 500 sccm in the processing container 51. Supplied to. For purging, _N2 gas was supplied to the processing container 51 at 100 to 1000 sccm.

The etching performed before the cycle of steps S1 to S6 described above, the etching of step S5, and the processing conditions at the time of each purging immediately after these etchings will be described. The pressure in the processing container 51 was 0.1 Torr to 10 Torr, and the temperature of the substrate was 0 ° C. to 100 ° C. ClF ₃ (chlorine trifluoride) gas was used as the etching gas. The purging was performed by supplying _N2 gas at 100 to 1000 sccm into the processing container 51.
Further, as the treatment conditions at the time of depolymerization in step S7, the pressure in the treatment container 51 was 0.1 Torr to 10 Torr, and the temperature of the substrate was 100 ° C. to 400 ° C. Further, when this depolymerization was performed, _N2 gas was supplied to the processing container 51 as a purge gas at 100 sccm to 2000 sccm.

In the etching before the cycle of steps S1 to S6, the polysilicon film 14 was etched in the vertical direction by 80 nm, and in the etching in step S5, the polysilicon film 14 was etched in the vertical direction by 60 nm. The cycle of steps S1 to S6 was performed three times. Therefore, in this evaluation test 2, the polysilicon film 14 is etched at a total of 260 nm. The time for forming the film and the subsequent purging, that is, the time from the start of step S1 to the end of step S4 was set to 5 minutes. The amount of change in weight between before and after the treatment in this evaluation test 2 was 128 wt ppm.

When the substrate after the execution of step S7 was confirmed as described above, the polyurea film 23 in the pores 16 of the SiOCN film 15 did not remain, and no damage was confirmed in the SiGe film 11. Therefore, from the results of this evaluation test 2, the effect on the processing of the present disclosure was confirmed.

W Wafer 11 SiGe film 14 Polysilicon film 15 SiOCN film 21 First film formation gas 22 Second film formation gas 23 Polyurea film 24 Etching gas 3 Substrate processing device 30 Control unit 5 Film formation module 51 Processing container 61 Mounting table 7 Gas shower head 8 Gas nozzle

Claims (13)

A film-forming gas is supplied to a substrate in which a silicon-containing film, a porous film, and an etching non-target film are provided adjacent to each other in this order, and the etching gas for etching the silicon-containing film is a hole in the porous film. A film forming step of forming a film formation in the pore portion to prevent the film from passing through the portion and being supplied to the non-etching film.
An etching step of supplying the etching gas to etch the silicon-containing film,
Etching method characterized by including. The etching method according to claim 1, further comprising a repeating step of repeating the film forming step and the etching step a plurality of times in this order. The film-forming gas includes a first film-forming gas and a second film-forming gas.
In the film forming step, the first film forming gas and the second film forming gas are sequentially supplied to the substrate, and the first film forming gas and the second film forming gas react with each other. The etching method according to claim 2, further comprising a step of forming the film-forming prevention film. Between the period for supplying the first film-forming gas and the period for supplying the second film-forming gas, and between the period for supplying the second film-forming gas and the period for supplying the etching gas. The etching method according to claim 3, further comprising a step of exhausting the periphery of the substrate between the period of supplying the etching gas and the period of supplying the first film-forming gas. The etching method according to claim 1, wherein the supply of the etching gas to the substrate and the supply of the film-forming gas to the substrate are performed at the same time. Claims 1 to 5 include a heating step of heating the substrate in order to vaporize and remove the passage prevention film from the pores after performing the film forming step and the etching step. The etching method according to any one. The etching method according to any one of claims 1 to 6, wherein an etching mask film is formed on the upper side of the non-etching film. The etching method according to any one of claims 1 to 7, wherein the passage prevention film is a polymer having a urea bond. With the processing container
A mounting portion for mounting a substrate provided in the processing container in which a silicon-containing film, a porous film, and an etching non-target film are provided adjacent to each other in this order in the lateral direction.
The process for forming an anti-passage film in the pores to prevent the etching gas for etching the silicon-containing film from passing through the pores of the porous film and being supplied to the non-etching film. A film forming gas supply unit that supplies the film forming gas into the container, and
An etching gas supply unit that supplies the etching gas into the processing container,
Etching device characterized by including. The etching apparatus according to claim 9, wherein a control unit for outputting a control signal is provided so that the supply of the film-forming gas and the supply of the etching gas are repeated a plurality of times in this order. The etching apparatus according to claim 9, further comprising a control unit 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 at the same time. The etching apparatus according to any one of claims 9 to 11, wherein the etching gas supply unit is a shower head provided so as to face the above-mentioned mounting unit. The claim is characterized in that the film-forming gas supply unit is provided so as to collide with the side wall of the processing container before the film-forming gas supplied from the film-forming gas supply unit is supplied to the substrate. Item 6. The etching apparatus according to any one of Items 9 to 12.

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