TW201939613A - Etching method and etching apparatus - Google Patents

Abstract

There is provided an etching method which includes: forming a blocking film configured to prevent an etching gas for etching a silicon-containing film from passing through each pore of a porous film and prevent the etching gas from being supplied to a film not to be etched, by supplying at least one film-forming gas to a substrate in which the silicon-containing film, the porous film, and the film not to be etched are sequentially formed adjacent to each other in a lateral direction; and etching the silicon-containing film by supplying the etching gas.

Description

Etching method and etching device

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

The interlayer insulating film which fills the wiring constituting the semiconductor device may be formed by a low-k film called a low-k film. The low-k film may be a porous film, for example. In a semiconductor device manufacturing process, a semiconductor wafer (hereinafter referred to as a wafer) in 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 recess for filling a wiring. A coating film is formed in the recessed portion in order to prevent exposure to the atmosphere until the wiring is buried in the recessed portion by the supply of a film-forming gas. Further, Patent Document 2 discloses a technique for etching an organic film formed in a recessed portion of a porous film, that is, a low-dielectric-constant film, by using a plasma containing a processing gas containing a predetermined amount of carbon dioxide.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] JP 2016-63141
[Patent Document 2] Patent No. 4940722

[Problems to be Solved by the Invention]

When manufacturing a semiconductor device, a multilayer body formed 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 adjacent to each other in order along the lateral direction. The wafer on the surface portion of the wafer may be subjected to a process of removing the polycrystalline silicon film. If the removal process of the polycrystalline silicon film is performed by dry etching, during the etching of the polycrystalline silicon film, an etching gas is supplied to the SiGe film through the SiOCN 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 sidewall of the SiGe film. Although the SiGe film is not subject to removal by etching, the sidewall is etched because an etching gas is supplied in this manner.

Here, for example, after the upper side of the polycrystalline silicon film is removed by anisotropic etching using a plasma, a process of removing the lower side of the polycrystalline silicon film by wet etching may be performed. The etching solution used for this wet etching has a lower permeability to the SiOCN film than the above-mentioned etching gas, and therefore suppresses the etching of the SiGe film. However, it takes a lot of work to perform multiple projects in this way. The process of miniaturization of the device in the wet etching process becomes impossible, and the thickness of the side wall of the SiOCN film tends to become smaller. When it becomes smaller, the permeability of the etching solution to the SiOCN film increases, and the SiGe film may be etched. The techniques described in the aforementioned Patent Documents 1 and 2 cannot solve such problems.

The present invention has been made in view of such circumstances, and an object thereof is to provide an etching gas to a substrate provided with a silicon-containing film, a porous film, and a non-etching film adjacent to each other in the lateral direction in order to remove the silicon-containing film (including silicon itself) In the case of), it is possible to prevent the non-etching target film from being etched.

[Means to solve the problem]

The etching method of the present invention is characterized by comprising:
A film-forming gas is supplied to a substrate provided with a silicon-containing film, a porous film, and a non-etching target film in a row adjacent to each other in order to prevent the etching gas for etching the silicon-containing film from passing through the pores of the porous film. A film forming process for preventing the film from being formed in the hole portion, which is supplied to the non-etching target film, and an etching process of supplying the etching gas to etch the silicon-containing film.

The etching device of the present invention is characterized by comprising:
Handling container
The mounting portion is provided in the processing container, and is used for mounting a substrate including a silicon-containing film, a porous film, and a non-etching target film adjacent to each other in a horizontal direction in order;
The film formation gas supply unit is configured to prevent the etching gas for etching the silicon-containing film from being supplied to the non-etching target film through the hole portion of the porous film, and a through prevention film is formed in the hole portion to the processing container. A film-forming gas is supplied therein; and an etching gas supply unit supplies the etching gas into the processing container.

[Inventive effect]

According to the present invention, a film-forming gas is supplied to a substrate provided with a silicon-containing film, a porous film, and a non-etching target film adjacent to each other in the horizontal direction. A pass-through prevention film is formed in the pore portion of the porous film. The prevention film prevents the etching gas containing the silicon-containing film from being supplied to the non-etching target film. Accordingly, when the silicon-containing film is etched, the etching of the non-etching target film is suppressed.

FIG. 1 is a vertical cross-sectional side view of a surface portion of a wafer W to be processed in accordance with an embodiment of the present invention. In the figure, 11 is a SiGe film, and a silicon oxide (SiO _x ) film 12 is laminated on the upper side of the SiGe film 11. A recessed portion 13 is formed in the laminated body of the silicon oxide film 12 and the SiGe film 11, and a polycrystalline silicon film 14 is buried in the recessed portion 13. In addition, between the sidewall of the polycrystalline silicon film 14 and the sidewall of the recessed portion 13 are provided SiOCN films 15 that surround the polycrystalline silicon film 14 and are in contact with the sidewall of the polycrystalline silicon film 14 and the sidewall of the recessed portion 13, respectively. Film made of oxygen, nitrogen and carbon. Therefore, the polycrystalline silicon film 14, the SiOCN film 15, and the SiGe film 11 are sequentially formed adjacently when viewed from the lateral direction. The SiOCN film 15 is an interlayer insulating film and is a porous film.

The outline of the processing in the embodiment of the present invention is as follows, and iteratively repeats: forming a polymer (polyurea) having a urea bond in the pore portion of the SiOCN film 15, that is, supply of a film-forming gas for a polyurea And the supply of an etching gas for etching the film to be etched, that is, the polycrystalline silicon film 14. That is, the polycrystalline silicon film 14 is etched at intervals, and the polyurea film is formed by filling the hole between the etching and the etching. This prevents the etching gas from passing through the SiOCN film 15 from the side of the SiOCN film 15 to etch the non-etching target film, that is, the sidewall of the SiGe film 11.

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

In this embodiment, a first film-forming gas containing a monomer, that is, an amine, and a second film-forming gas containing a monomer, that is, an isocyanate, are supplied to a 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 (isocyanate) cyclohexane (H6XDI) is used. Hexylamine may be used as the amine, and tert-butyl isocyanate may be used as the isocyanate. The amine and isocyanate capable of forming a polyurea film are not limited to this example, and specific examples will be given later.

Next, processing performed on the wafer W will be described with reference to FIGS. 2 to 4. FIGS. 2 to 4 are schematic diagrams showing how the surface portion of the wafer W described in FIG. 1 changes through processing. In the figure, the pores formed in the SiOCN film 15 are labeled 16, the amine is the first film-forming gas is 21, the isocyanate is the second film-forming gas is 22, the polyurea film is 23, and IF ₇ is The etching gas is labeled 24. Each of the processes shown in FIGS. 2 to 4 is carried out in a state where the wafer W is carried into a processing container, and the inside of the processing container is evacuated to a vacuum atmosphere having 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 on the hole wall. Next, the supply of the first film-forming gas 21 in the processing container is stopped, and the inside of the processing container is in a state where exhaust gas and, for example, N ₂ (nitrogen) gas, that is, supply of clean gas are performed (step S2, FIG. 2 (b)), The first film-forming gas 21 that has not flowed into the hole portion 16 is removed by a flow of a clean gas that is exhausted.

Next, a 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 on the hole portion 16 The first film-forming gas 21 reacts to form a polyurea film 23, which is an anti-pass film for the etching gas, and the hole 16 is closed. After that, the supply of the second film-forming gas 22 in the processing container is stopped, and the supply of exhaust gas and clean gas in the processing container is stopped (step S4, FIG. 2 (d)), and the second component that has not flowed into the hole portion 16 The membrane gas 22 is removed by a flow of a clean gas that is exhausted.

Next, an etching gas 24 is supplied into the processing container (step S5, FIG. 3 (e)), the polycrystalline silicon film 14 is etched, and the side wall on the upper side 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 passage of the etching gas 24 through the hole portion 16 is prevented, so that the etching gas 24 can be prevented from transmitting from the side of the SiOCN film 15 to etch the sidewall of the SiGe film 11. After that, the supply of the etching gas 24 in the processing container is stopped, and the inside of the processing container is in a state where exhaust gas and clean gas are supplied (step S6, FIG. 3 (f)). The etching gas 24 remaining in the processing container passes through the The air flow of the clean gas for exhaust in the processing vessel is removed.

After that, the first film-forming gas 21 is supplied into the processing container. That is, step S1 is performed again. In the above step S5, the polycrystalline silicon film 14 is exposed by the side wall on the upper side of the etched SiOCN film 15. Therefore, the first film-forming gas 21 supplied in the second step S1 is supplied to the SiOCN film 15 and the first. In the first step S1, the hole portion 16 to which the first film-forming gas 21 is supplied is compared with the hole portion 16 below, and is adsorbed on the hole wall.

After that, the supply of the exhaust gas and the clean gas in the processing container in step S2 is performed again, and then the supply of the second film-forming gas 22 in the processing container in step S3 is performed again. The second film-forming gas 22 is also supplied to the second film-forming gas 21 in the same manner as the first film-forming gas 21 supplied to the processing container in the second step S1. The pore portion 16 of the SiOCN film 15 of the film gas 22 is lower than the pore portion 16, and reacts with the first film-forming gas 21 adsorbed by the pore portion 16 to form a polyurea film 23. Therefore, in the second step S3, the area where the polyurea film 23 is formed in the SiOCN film 15 is enlarged downward (FIG. 4 (a)).

After that, the exhaust gas and clean gas are supplied in step S4, and then the etching gas 24 is supplied in step S5. The polycrystalline silicon film 14 is further etched downward, and the exposed area in the sidewall of the SiOCN film 15 is expanded downward. As described above, the area where the polyurea film 23 is formed in the SiOCN film 15 is enlarged downward from the second step S3, and accordingly, the holes near the sidewall of the SiOCN film 15 are newly exposed through the etching of the polycrystalline silicon film 14 The portion 16 is in a state of being buried in 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 hole portion 16 of the SiOCN film 15 (FIG. 4 (b)). After the etching, the exhaust and the supply of the clean gas in step S6 are performed again.

The steps S1 to S6 that are sequentially performed in this way are set as a 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 side walls of the SiGe film 11 are etched, and the polycrystalline silicon film 14 is etched downward. For example, the polycrystalline silicon film 14 is completely etched, and after a predetermined number of cycles are completed (FIG. 4 (c)), the wafer W is heated at, for example, 100 ° C. or higher, and preferably 300 ° C. or higher, so that the polyurea buried in the hole 16 is filled. The film 23 is vaporized or depolymerized and vaporized, and is removed from the wafer W (FIG. 4 (d)). The etching residue attached 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 a wafer W in which the polycrystalline silicon film 14 has been etched in this manner, and the polyurea film 23 has been removed. In the recess 17 formed by removing the polycrystalline silicon film 14, a gate of a semiconductor device is formed in a subsequent process, for example.

According to the processing according to the embodiment of the invention, the polycrystalline silicon film 14 can be etched by the etching gas while the SiGe film 11 is suppressed from being etched by the etching gas. In addition, in the process of the embodiment of the present invention, it is not necessary to switch the atmosphere around the wafer W from the vacuum atmosphere in which the plasma treatment is performed, as compared with the case where the wet etching process is performed after the plasma treatment described in the prior art. Atmospheric atmosphere for wet etching. Therefore, the processing of the embodiment of the present invention has the advantage that the time and effort required for processing can be reduced. In addition, since no plasma is required for the processing according to this embodiment, each film on the surface of the wafer W is not damaged by the plasma, and it also has the advantage of improving the reliability of the semiconductor device formed by the wafer W. However, the use of plasma for etching is also included in the right scope of the present invention.

The exhaust gas flow rate of the processing container in the above steps S1 to S6 may be constant. The exhaust gas flow rate in steps S2, S4, and S6 regarding the removal of unnecessary gas in the processing container may be such that the gas can be removed more reliably. It may be set to be 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 is not performed, and unnecessary gas may be removed only by exhaust gas. In addition, as described above, the etching selectivity of the polyurea film 23, that is, the IF ₇ gas, is low. Therefore, if the polyurea film 23 is formed on the surface of the polycrystalline silicon film 14, the polycrystalline silicon film 14 is difficult to be etched. However, the first film-forming gas 21 and the second film-forming gas 22 unnecessary in the aforementioned steps S2 and S4 are removed. That is, by performing steps S2 and S4, the polysilicon film 14 can be more reliably etched.

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

Although the non-etching target film is the SiGe film 11 in the above embodiment, it may be a Si film, for example. The non-etching target film may be a film other than a silicon-containing film such as the Si film or the SiGe film 11. 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 can be formed.

The film-forming gas for forming 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 hexamethylene diamine can be used as the amine. As the amine, H6XDI can be used as the isocyanate. However, as the amine, in addition to the above compounds, for example, 1,6-hexanediamine, cyclohexylamine, hexylamine, butylamine, and tert-butylamine can be used. As the isocyanate, in addition to the compounds described above, for example, 1,6-hexanediisocyanate, cyclohexyl isocyanate, hexyl isocyanate, butyl isocyanate, and t-butyl isocyanate can be used. That is, one selected from the compounds of the amines listed above and one selected from the compounds of the isocyanates listed above can be used for the film formation of the polyurea film 23, respectively. If the change of the reaction between the isocyanate and the amine is further explained, as shown in FIG. 6 in this reaction, a functional molecule may be used as a raw material monomer constituting the film-forming gas. In addition, the gas generated by thermally 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 initiate a polymerization reaction, and a 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 examples described 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, but 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 between If there is no problem in practice, it may be considered that the polyurea film 23 remains. Therefore, the case where the removal of the polyurea film 23 in step S7 is not included in the scope of rights of the present invention.

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

The loading / 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; and a side portion of the normal-pressure transfer chamber 33 is provided for mounting a crystal accommodating the wafer W. The wafer carrier mounting stage 35 of the circular carrier 34. In the figure, 36 is an azimuth chamber adjacent to the atmospheric pressure transfer chamber 33. The wafer W and the first substrate transfer mechanism 32 are positioned by optically calculating an eccentricity amount to rotate the wafer W. The first substrate transfer mechanism 32 transfers the wafer W between the wafer carrier 34 on the wafer carrier mounting table 35 and the positioner chamber 36 and the 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 and the heat treatment module 40 and the etching module 5. W. 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 set to a vacuum atmosphere, and the load lock chamber 41 is provided between the processing container in their vacuum atmosphere and the atmospheric pressure transfer chamber 33. The method of transferring wafers W is switched to a normal pressure atmosphere and a vacuum atmosphere.

43 in the figure is a gate valve with free opening / closing, which is respectively arranged between the atmospheric 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 heat treatment module 40 includes the above-mentioned processing container, an exhaust mechanism that exhausts the inside of the processing container to form a vacuum atmosphere, and a mounting table installed in the processing container and capable of heating the mounted wafer W, and is configured as follows: The aforementioned step S7 can be performed.

Next, the etching module 5 will be described with reference to a longitudinal sectional side view of FIG. 8 and a transverse sectional plan view of FIG. 9. The etching module 5 includes, for example, a circular processing container 51, and the processing in steps S1 to S6 can be performed on the wafer W 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 air-tight vacuum container, and a circular mounting table 61 on which a wafer W is formed on a horizontal surface (upper surface) is provided on the lower side of the processing container 51. In the figure, 62 is a platform heater buried in the mounting table 61, and the wafer W is heated to a predetermined temperature in such a manner that the processes of steps S1 to S6 described above can be performed. In the figure, 63 is a pillar which supports the mounting part 61, that is, the mounting table 61 on the bottom surface of the processing container 51. In the figure, 64 are three vertical lifting pins. The lifting mechanism 65 can protrude / subject from the surface of the mounting table 61, and transfer the wafer W between the second substrate transfer 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 as viewed in a plane and approaches the side of the mounting table 61 to form a ring-shaped lower section 52 in a plan view. The upper surface of the lower section 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, an upper side of the lower section portion 52 is used as a side wall body portion 53. As described later, the film-forming gas (the first film-forming gas and the second film-forming gas) is ejected so as to collide with the side wall body portion 53 forming the member to be hit. It functions as a guide member that reaches the upper surface and is supplied to the mounting table 61. In the figure, 54 is a side wall heater that is embedded in the lower section 52 and the side wall main body section 53, respectively. The temperature of the surface of the lower stage portion 52 and the side wall body portion 53 in the inner side of the processing container 51 is adjusted by the side wall heater 54, the temperature of the film-forming gas colliding with the side wall body portion 53, and the atmosphere in the processing container 51. The temperature is adjusted.

In FIG. 8, reference numeral 55 denotes a transfer port of the wafer W. An opening is provided in a portion of the side wall body portion 53 that collides with the film-forming gas away from the circumferential direction of the processing container 51. The gate valve 43 is opened and closed freely. Make up. In the figure, reference numeral 66 denotes an open exhaust port provided on the bottom surface of the processing container 51, and is connected to an exhaust mechanism 67 including a vacuum pump, a valve, and the like via an exhaust pipe (see FIG. 8). The pressure in the processing container 51 is adjusted by adjusting the exhaust flow rate through the exhaust port 66 of the exhaust mechanism 67.

The gas shower head 7 forming the etching gas supply portion is provided above the mounting table 61 and in the patio portion 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 provided horizontally so as to form a lower surface portion of the gas shower head 7. In order to discharge the gas to the mounting table 61 in a shower shape, a plurality of gas discharge holes 74 are dispersedly formed. The gas diffusion space 72 is a flat space formed by being divided by the shower plate 71 in order to supply gas to each of the gas discharge holes 74. The diffuser plate 73 is provided horizontally so that the gas diffusion space 72 is divided into upper and lower portions. In the figure, 75 is a through-hole formed in the diffuser plate 73, and a plurality of perforations are dispersed in the diffuser plate 73 and perforated. 77 in the figure is a patio heater, and the temperature of the gas shower head 7 is adjusted.

A downstream end of a gas supply pipe 68 is connected to the upper side of the gas diffusion space 72. An upstream side of the gas supply pipe 68 is connected to a supply source 60 of the IF ₇ gas via a flow rate adjustment unit 69. The flow rate adjustment unit 69 is configured by 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. Each of the flow rate adjustment sections described later is also configured in the same manner as the flow rate adjustment section 69, and adjusts the flow rate of the gas supplied to the downstream side of the pipe in which the flow rate adjustment section is provided.

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 portion 53 of the processing container 51. That is, the film-forming gas system is supplied from a gas supply unit provided differently from the gas shower head 7. 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 in the lateral direction, for example. The dotted arrows in FIG. 8 and FIG. 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 their arrows, the gas nozzle 8 discharges gas horizontally along the diameter of the wafer W. The side of the side wall body portion 53 is at the front end in the direction in which the gas is discharged, and therefore, the discharged gas collides with the side wall body portion 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 a member to be hit. The gas colliding with the side wall body portion 53 in this manner flows along the surface of the lower stage portion 52 and the surface of the mounting table 61 as indicated by the dotted arrows in FIG. 8 and is supplied to the wafer W.

Compared with the configuration in which the gas nozzle 8 configured as described above directly faces the wafer W and the gas outlet of the gas nozzle 8 directly faces the wafer W, the gas discharged before reaching the wafer W moves a long distance. Therefore, the purpose of making the gas fully diffuse in the lateral direction can be achieved. That is, the gas nozzle 8 is configured to discharge gas toward the side wall body portion 53 so that each gas can be supplied with high uniformity in the surface of the wafer W.

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

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

The upstream side of the gas introduction pipe 83 is connected to the gasification unit 102 via the flow rate adjustment unit 101 and the valve V4 in this order. The above-mentioned H6XDI is stored in a liquid state in the vaporization section 102, and the vaporization section 102 includes a heater (not shown) that heats the H6XDI. In addition, one end of a gas supply pipe 104 is connected to the gasification unit 102, and the other end of the gas supply pipe 104 is connected to a N ₂ (nitrogen) gas supply source 106 in sequence through a valve V5 and a gas heating unit 105. According to such a configuration, the heated N ₂ gas is supplied to the gasification unit 102 to vaporize the H6XDI in the gasification unit 102, and a mixed gas of the N ₂ gas and the H6XDI gas used for the gasification 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 on the downstream side of the gas heating section 105 and a portion on the upstream side 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 a valve V6. The downstream side of the valve V4 of the pipe 83 and the upstream side of the flow rate adjustment section 101. Therefore, when the second film-forming gas is not supplied to the gas nozzle 8, the N ₂ gas bypass gasification unit 102 heated by the gas heating unit 105 is introduced into the gas nozzle 8.

In order to prevent liquefaction of H6XDA and H6XDI in the film-forming gas in circulation 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. The temperature of the film-forming gas discharged from the gas nozzle 8 is adjusted by the piping heater 76, the gas heating sections 95, 105, and the heaters provided in the vaporization sections 92, 102. In addition, for the convenience of illustration, the piping heater 76 is shown in only a part of the gas supply pipe 81 and the gas introduction pipes 82 and 83. However, the piping heater 76 is provided in a relatively wide range throughout the pipes so as to prevent the above-mentioned liquefaction. .

The upstream side of the flow adjustment section 91 in the gas introduction pipe 82, the flow adjustment section 91, the vaporization section 92, the valves V1 to V3, the gas supply pipes 94 and 97, the gas heating section 95, and the N ₂ gas supply source 96 are set as First gas supply mechanism 9A. The upstream side of the flow rate adjustment section 101 in the gas introduction pipe 83, the flow rate adjustment section 101, the gasification section 102, the valves V4 to V6, the gas supply pipes 104, 107, the gas heating section 105, and the N ₂ gas supply source 106 It is set as the 2nd 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 incorporates instructions (each step) in such a manner that the aforementioned processing of the wafer W and the transfer of the wafer W are performed. The program is stored in a computer storage medium such as an optical disk, a hard disk, an optical magnetic disk, a DVD, etc. Installed in the control section 30. The control section 30 outputs a control signal to each section of the substrate processing apparatus 3 according to the program, and controls the operation of each section. 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 second substrate transfer mechanism 42, and the operation of the positioner chamber 36 are controlled by control signals. The operation of the etching module 5 includes the adjustment of the output of each heater, the supply / cutoff of the gas from the first gas supply mechanism 9A, the second gas supply mechanism 9B, the IF ₇ gas from the gas shower head 7, and the gas from Each operation of supplying / cutting off each gas of the nozzle 8, adjusting the exhaust flow rate by the exhaust mechanism 67, and raising and lowering the lift pin 64 by the lift mechanism 65. The control unit 30 and the etching module 5 correspond to the etching apparatus of the present invention.

The transport path of the wafer W in the substrate processing apparatus 3 will be described. As illustrated in FIG. 1, the wafer carrier 34 having the wafers W on which the respective films are formed is placed on a wafer carrier mounting table 35. Next, the wafer W is transferred in the order of the normal pressure transfer chamber 33 → the orientation device 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. The cycle consisting of steps S1 to S6 is repeated as described above, and the wafer W is processed. Next, the wafer W is transferred to the heat treatment module 40 and is subjected to the process of step S7. Thereafter, the wafer W is transferred in the order of the load lock chamber 41 → the atmospheric pressure transfer chamber 33, and returns to the wafer carrier 34.

Next, for the correspondence between the above-mentioned 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, refer to FIG. 10 to FIG. 13 will be described. The first film-forming gas is supplied from the first gas supply mechanism 9A, and the N ₂ gas is supplied to the gas nozzle 8 from the second gas supply mechanism 9B. The mixed gas is 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. The N ₂ gas is discharged from the gas nozzle 8 as a clean gas, and step S2 is performed (FIG. 11). After that, the N ₂ 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 nozzles 8 respectively, and the mixed gas is discharged from the gas nozzles 8. Step S3 is performed ( Figure 12). After that, N ₂ gas is supplied to the gas nozzle 8 from the first gas supply mechanism 9A and the second gas supply mechanism 9B in the same manner as step S2, and the N ₂ gas is discharged from the gas nozzle 8 as a clean gas. Proceed (Figure 11).

After that, for example, in a state where the supply of the gas to the gas nozzle 8 from the first gas supply mechanism 9A and the second gas supply mechanism 9B is stopped, the supply of the IF ₇ gas from the gas shower head 7 is performed, and step S5 is performed (FIG. 13). . Further, the step S5 as long as the Si is capable of ClF ₃ gas, F ₂ gas or the like of the F-based etching gas can be used any of a gas. After that, N ₂ gas is supplied to the gas nozzle 8 from the first gas supply mechanism 9A and the second gas supply mechanism 9B in the same manner as steps S2 and S4, and the N ₂ gas is discharged from the gas nozzle 8 as a clean gas. S6 is performed (Fig. 11).

When the processing by the etching module 5 is performed as described above, the output of the piping heater 76 and the stage heater 62 is controlled so that the temperature of the wafer W is lower than the film-forming gas (the first film-forming film) ejected from the gas nozzle 8 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. Regarding the temperature of the side wall body portion 53, the output of the piping heater 76 and the side wall heater 54 is controlled so as to be lower than the temperature of the film-forming gas discharged from the gas nozzle 8 so as to collide with the side wall body portion 53. The temperature of the film-forming gas can also be reduced. By reducing the temperature of the colliding film-forming gas in this way, the temperature of the film-forming gas when supplied to the wafer W becomes lower, and the film-forming gas can be more effectively adsorbed on the wafer W. In this case, in order to prevent film formation on the side wall body portion 53, for example, the output of the platform heater 62 and the side wall heater 54 is controlled such that the temperature of the side wall body portion 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 the sacrificial film from which W has been removed, it is preferable that an etching gas that forms a pattern on the wafer W can be more uniformly supplied on the surface of the wafer W. Among the gas nozzle 8 and the gas shower head 7, the gas shower head 7 which supplies the gas in a shower shape is considered to be capable of supplying a more uniform gas in the surface of the wafer W. Therefore, the gas shower head 7 has a good gas diffusivity, and it is possible to supply a more uniform gas from each of the gas discharge holes 74, and the flow path formed in the interior tends to be narrow and the flexibility is high. That is, the gas flowing through the flow path in the gas shower head 7 experiences a large pressure loss. Therefore, the etching module 5 is configured so that the etching gas is supplied from the gas shower head 7 so that it can be supplied to the wafer W with high uniformity, and the film-forming gas is used to prevent pressure loss in the flow path. It is liquefied and is discharged from the gas nozzle 8.

In the etching module 5, the first film-forming gas and the second film-forming gas may be discharged from different gas nozzles. In addition, the gas nozzle 8 may be configured to have a wide discharge port in the lateral direction, for example. The exhaust port 66 is not limited to the opening in the bottom of the processing container 51, and may be opened in a side wall below the processing container 51, for example. The clean gas can be discharged from the gas shower head 7. However, instead of the gas shower head 7 in the patio portion of the processing container 51, for example, a gas supply portion having a gas discharge opening that opens concentrically around the wafer W in a plan view is provided to supply etching to the wafer W Gas is also available. That is, the etching gas supply unit is not limited to the configuration of the gas shower head 7.

The substrate processing apparatus 3 may be configured by connecting, for example, a film forming module and an etching module each including a processing container formed in a vacuum atmosphere in a vacuum atmosphere transfer chamber including a wafer W transfer mechanism. In this case, the film forming module is configured to perform steps S1 to S4, and the etching module is configured to perform steps S5 and S6, respectively. With the transfer mechanism provided in the above-mentioned vacuum atmosphere transfer chamber, the etching module and the film forming module are performed. The wafer W is repeatedly moved between them, and the cycle consisting of steps S1 to S6 is repeated accordingly. That is, film formation and etching may be performed in mutually different processing containers. However, by providing the substrate processing apparatus 3 with the etching module 5 described above, when the above-mentioned cycle is repeated, the moving time between such modules can be saved, and thus productivity can be improved.

However, FIG. 14 shows an etching module 50 which is a modified example 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 a downstream end of the gas supply pipe 81 is connected to the gas shower head 7, and a 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 respectively supplied into the processing container 51 from the gas shower head 7. In addition, since the film-forming gas is discharged from the gas shower head 7 in this manner, it is not necessary to provide the lower section 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.

The order in which the first film-forming gas containing an amine, the second film-forming gas containing an isocyanate, the etching gas, and the clean gas are supplied into the processing container 51 is not limited to the aforementioned example. For example, the first film-forming gas and the second film-forming gas may be 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 gases, the clean gas, the etching gas, and the clean gas. The supply of the film-forming gas, the etching gas, and the clean gas according to this sequence is set to one cycle. By repeating this cycle for one wafer W, the film formation of the polyurea film 23 and the polycrystalline silicon film 14 are repeated alternately. Etching is also possible. The first film-forming gas, the second film-forming gas, and the etching gas may be simultaneously supplied into the processing container 51. That is, the polycrystalline silicon film 14 may be etched while the polyurea film 23 is formed in the hole portion 16 of the SiOCN film 15. In this case, after supplying the first film-forming gas, the second film-forming gas, and the etching gas, a clean 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 clean gas may be set to one cycle, and the cycle may be repeated for one wafer W to process. When the etching modules 5 and 50 are processed, a signal for controlling each of the etching modules 5 and 50 is output from the control unit 30 so that such processing is performed.
The present invention is not limited to the foregoing embodiments, and the embodiments can be appropriately changed, and the embodiments can be combined with each other.

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

Next, the evaluation test 2 will be described. In this evaluation test 2, a test device constituted by supplying various gases in a processing container 51 formed in a vacuum atmosphere in the same manner as the etching modules 5 and 50 described above was used, and the test substrate was subjected to FIGS. 2 to 5 Described processing. That is, after repeating the cycle of steps S1 to S6, the heat treatment for depolymerizing the polyurea film 23 in step S7 is performed. The test substrate has a film structure as described 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. The repeated cycle of steps S1 to S6 described above is performed after the etching gas is supplied into the processing container 51 and the upper portion of the polycrystalline silicon film 14 is etched to purify the inside of the processing container 51.

Regarding the processing conditions in steps S1 to S4, that is, the processing at each purification time immediately after the first film-forming gas is supplied, the second film-forming gas is supplied, and immediately after the first film-forming gas or the second film-forming gas is supplied. 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 was used as the first film-forming gas, and tert-butyl isocyanate was used as the second film-forming gas. The first film-forming gas and the second film-forming gas were 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.

The etching conditions 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 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. As the etching gas, ClF ₃ (chlorine trifluoride) gas was used. For purification, N ₂ gas is supplied into the processing container 51 at 100 to 1000 sccm.
In addition, as the processing conditions during the 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. When performing the depolymerization, N ₂ gas is supplied as a clean gas to the processing container 51 at 100 sccm to 2000 sccm.

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

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

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 film

24‧‧‧etching gas

3‧‧‧ substrate processing device

30‧‧‧Control Department

5‧‧‧Film forming module

51‧‧‧handling container

61‧‧‧mounting table

7‧‧‧Gas shower head

8‧‧‧gas nozzle

[Fig. 1] A longitudinal sectional side view of a surface of a wafer to be etched according to the present invention.

FIG. 2 is a process drawing explaining an etching process of the present invention.

FIG. 3 is a process drawing explaining an etching process of the present invention.

FIG. 4 is a process drawing explaining an etching process of the present invention.

[Fig. 5] A longitudinal sectional side view of the surface of the wafer after the etching is completed.

[Fig. 6] An explanatory diagram of a reaction in which a polymer having a urea bond is generated by a film-forming gas.

[Fig. 7] A plan view of a substrate processing apparatus for etching.

[Fig. 8] A longitudinal sectional side view of an etching module provided in the substrate processing apparatus.

[Fig. 9] A cross-sectional plan view of the etching module.

[Fig. 10] An explanatory diagram of the operation of the 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 etching module.

[Fig. 13] An explanatory diagram of the operation of the etching module.

[Fig. 14] A longitudinal sectional side view of a configuration example of another etching module.

15 is a longitudinal sectional side view of a wafer in an evaluation test.

Claims (13)

An etching method, comprising: A film-forming gas is supplied to a substrate provided with a silicon-containing film, a porous film, and a non-etching target film in a row adjacent to each other in order to prevent the etching gas for etching the silicon-containing film from passing through the pores of the porous film. A film-forming process for preventing the film from being formed in the hole portion supplied to the non-etching target film; and An etching process in which the etching gas is supplied to etch the silicon-containing film. For example, the application of the etching method of the scope of the patent No. 1 The method includes repeating the film-forming process and the etching process sequentially in a plurality of repetitions. For example, the etching method in the scope of patent application No. 2 The film-forming gas includes a first film-forming gas and a second film-forming gas, The film formation process includes sequentially supplying the first film formation gas and the second film formation gas to the substrate, and causing the first film formation gas and the second film formation gas to react with each other to form the passage prevention film. engineering. For example, the etching method of the third item of the patent application, in which The method includes supplying the etching gas between a period during which the first film-forming gas is supplied and a period during which the second film-forming gas is supplied, and between a period during which the second film-forming gas is supplied and a period during which the etching gas is supplied. The process of exhausting the periphery of the substrate between the period of time and the period of supplying the first film-forming gas. For example, the application of the etching method of the scope of the patent No. 1 The supply of the etching gas to the substrate and the supply of the film-forming gas to the substrate are performed simultaneously. For example, the application of the etching method in any one of items 1 to 5, wherein Including: after the film formation process and the etching process are performed, a heating process for heating the substrate to prevent the vaporization and removal of the film from the hole portion is performed. For example, the application of the etching method in any one of items 1 to 5, wherein An etching mask film is formed on the upper side of the non-etching target film. For example, the application of the etching method in any one of items 1 to 5, wherein The aforementioned preventive film is a polymer having a urea bond. An etching device, comprising: Handling container The mounting portion is provided in the processing container, and is used for mounting a substrate on which a silicon-containing film, a porous film, and a non-etching target film are arranged adjacent to each other in the horizontal direction. The film formation gas supply unit is configured to prevent the etching gas for etching the silicon-containing film from being supplied to the non-etching target film through the hole portion of the porous film, and a through prevention film is formed in the hole portion to the processing container. Supply film-forming gas inside; and The etching gas supply unit supplies the etching gas into the processing container. For example, the etch device for item 9 of the patent scope, in which A control unit is provided to output a control signal such that the supply of the film-forming gas and the supply of the etching gas are sequentially repeated a plurality of times. For example, the etch device for item 9 of the patent scope, in which A control unit is provided to output a control signal such that the supply of the etching gas to the substrate and the supply of the film-forming gas to the substrate are performed simultaneously. For example, an etching device according to any one of claims 9 to 11, wherein The etching gas supply unit is a shower head provided facing the mounting portion. For example, an etching device according to any one of claims 9 to 11, wherein 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.