JP2022002337A - Substrate processing method and plasma processing apparatus - Google Patents

Abstract

To provide a technique to improve the selection ratio of etching of a film containing silicon to etching of a mask in plasma etching.SOLUTION: A substrate processing method according to an illustrative embodiment includes a step of providing a substrate into a chamber of a plasma processing apparatus. The substrate has a silicon-containing film and a mask provided on the silicon-containing film. The substrate processing method further includes a step of controlling the temperature of a substrate support on which the substrate is mounted to 0°C or less. The substrate processing method further includes a step of etching the silicon-containing film by plasma generated from a first processing gas including a hydrofluoric gas and at least one carbon-containing gas selected from the group consisting of a fluorocarbon gas and a hydrofluorocarbon gas. In the step of etching, the film is etched by a chemical species from the plasma. In the first processing gas from which an inert gas is removed, the hydrofluoric gas has the largest flow rate.SELECTED DRAWING: Figure 1

Description

Exemplary embodiments of the present disclosure relate to substrate processing methods and plasma processing equipment.

Patent Document 1 discloses a method of etching a film in a substrate. The membrane contains silicon and the substrate further has a mask provided on the membrane. The mask contains amorphous carbon or organic polymer. For etching in this method, plasma generated from a processing gas containing a hydrocarbon gas and a fluorohydrocarbon gas is used.

Japanese Unexamined Patent Publication No. 2016-39310

The present disclosure provides a technique for improving the selection ratio of etching of a silicon-containing film to etching of a mask in plasma etching.

In one exemplary embodiment, a substrate processing method is provided. The substrate processing method comprises the step of providing the substrate into the chamber of the plasma processing apparatus. The substrate has a silicon-containing film and a mask provided on the silicon-containing film. The substrate processing method further includes a step of controlling the temperature of the substrate support on which the substrate is placed to 0 ° C. or lower. The substrate treatment method is a step of etching a silicon-containing film with plasma generated from a first treatment gas containing at least one carbon-containing gas selected from the group consisting of hydrogen fluoride gas and fluorocarbon gas and hydrofluorocarbon gas. Including further. In the etching step, the silicon-containing film is etched by the chemical species from the plasma. Among the first treated gases excluding the inert gas, the flow rate of the hydrogen fluoride gas is the highest.

According to the present disclosure, it is possible to provide a technique for improving the selection ratio of etching of a silicon-containing film to etching of a mask in plasma etching.

It is a flowchart which shows an example of the substrate processing method which concerns on 1st Embodiment. It is a figure which shows schematically the plasma processing apparatus of an example. It is a partially enlarged sectional view of the substrate of an example provided in process ST11. It is a partially enlarged sectional view of the substrate of an example after executing the substrate processing method shown in FIG. 1. It is a timing chart about an example substrate processing method. It is a graph which shows the result of the experiment 1 performed for the evaluation of the substrate processing method shown in FIG. It is a graph which shows the result of the experiment 2 performed for the evaluation of the substrate processing method shown in FIG. FIG. 8A is a graph showing the results of Experiment 3, and FIG. 8B is a graph showing the results of Experiment 4. It is a flowchart which shows an example of the substrate processing method which concerns on 2nd Embodiment. It is a flowchart which shows an example of the substrate processing method which concerns on 3rd Embodiment. It is a flowchart which shows another example of the substrate processing method which concerns on 3rd Embodiment.

Hereinafter, various exemplary embodiments will be described.

In one exemplary embodiment, a substrate processing method is provided. The substrate processing method comprises the step of providing the substrate into the chamber of the plasma processing apparatus. The substrate has a silicon-containing film containing a silicon oxide film and a mask provided on the silicon-containing film. The substrate processing method includes a step of controlling the temperature of the substrate support on which the substrate is placed to 0 ° C. or lower. The substrate treatment method etches a silicon-containing film with plasma generated from a first treatment gas containing at least one carbon-containing gas selected from the group consisting of hydrogen fluoride gas and fluorocarbon gas and hydrofluorocarbon gas. Further includes steps. In the etching step, the silicon-containing film is etched by the chemical species from the plasma. Among the first treatment gases excluding the inert gas, the flow rate of hydrogen fluoride gas is the highest. According to this embodiment, by using plasma generated from the first processing gas having the highest flow rate of hydrogen fluoride gas in the total flow rate excluding the inert gas, silicon is contained for etching of the mask. The selection ratio of film etching is improved.

In one exemplary embodiment, the flow rate of hydrogen fluoride gas with respect to the total flow rate of the first treatment gas excluding the inert gas may be 70% by volume or more.

In one exemplary embodiment, the fluorocarbon gas is selected from the group consisting of _{CF 4} , C ₂ F ₂ , C ₂ F ₄ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ and C ₅ F _8. It may be at least one kind.

In one exemplary embodiment, the fluorocarbon gas can be a C ₄ F ₈ gas.

In one exemplary embodiment, the hydrofluorocarbon gas is CHF ₃ , CH ₂ F ₂ , CH ₃ F, C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F _2. , C ₃ HF ₇ , C ₃ H ₂ F ₂ , C ₃ H ₂ F ₆ , C ₃ H ₂ F ₄ , C ₃ H ₃ F ₅ , C ₄ H ₅ F ₅ , C ₄ H ₂ F ₆ , C ₅ It may be at least one selected from the group consisting of H ₂ F ₁₀ , c-C ₅ H ₃ F ₇ and C ₃ H ₂ F _4.

In one exemplary embodiment, the hydrofluorocarbon gas may be at least one selected from the group consisting of _{C 3} H ₂ F ₄ gas and C ₄ H ₂ F _{6 gas.}

In one exemplary embodiment, the first treatment gas may further comprise at least one selected from the group consisting of oxygen-containing gas and halogen-containing gas.

In one exemplary embodiment, the first treatment gas may further comprise at least one selected from the group consisting of phosphorus-containing gas, sulfur-containing gas and boron-containing gas.

In one exemplary embodiment, the flow rate of hydrogen fluoride gas to the total flow rate of the first treatment gas excluding the inert gas may be 96% by volume or less.

In one exemplary embodiment, the silicon-containing film is at least one selected from the group consisting of a silicon oxide film, a laminated film containing a silicon oxide film and a silicon nitride film, and a laminated film containing a silicon oxide film and a polysilicon film. May be.

In one exemplary embodiment, the mask may be a carbon-containing mask or a metal-containing mask.

In one exemplary embodiment, the carbon-containing mask may be formed from at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide.

In one exemplary embodiment, the substrate processing method further comprises the step of generating plasma from a second processing gas in the chamber. In the second step of generating plasma from the processing gas, the inside of the chamber is cleaned by chemical species from the plasma.

In one exemplary embodiment, the second treatment gas may comprise at least one selected from the group consisting of a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas.

In one exemplary embodiment, the substrate processing method further comprises the step of generating plasma from a third processing gas in the chamber prior to the step of providing the substrate. In the step of generating plasma from the third processing gas, a precoat is formed on the inner wall of the chamber.

In one exemplary embodiment, the third treatment gas may include a carbon-containing gas.

In another exemplary embodiment, a substrate processing method is provided. The substrate processing method comprises the step of providing the substrate into the chamber of the plasma processing apparatus. The substrate has a silicon-containing film containing a silicon oxide film and a mask provided on the silicon-containing film. The substrate processing method is at least one carbon-containing gas selected from the group consisting of _{hydrogen fluoride gas and C 4} F ₈ gas, C ₃ H ₂ F ₄ gas and C ₄ H ₂ F _{6 gas in the chamber.} The step of etching the silicon-containing film with the plasma generated from the first processing gas containing the above is further included. In the etching step, the silicon-containing film is etched by the chemical species from the plasma. The flow rate of hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding the inert gas is 70% by volume or more and 96% by volume or less. According to this embodiment, by using plasma generated from the first processing gas in which the flow rate of hydrogen fluoride gas is 70% by volume or more and 96% by volume or less with respect to the total flow rate excluding the inert gas. , The selection ratio of etching of the film containing silicon to the etching of the mask is improved.

In one exemplary embodiment, the first treatment gas may further comprise at least one selected from the group consisting of oxygen-containing gas and halogen-containing gas.

In one exemplary embodiment, the first treatment gas may further contain a phosphorus-containing gas.

In another exemplary embodiment, a substrate processing method is provided. The substrate processing method comprises the step of providing the substrate into the chamber of the plasma processing apparatus. The substrate has a silicon-containing film and a mask provided on the silicon-containing film. The substrate processing method further includes a step of etching the silicon-containing film with plasma generated from the first processing gas containing hydrogen fluoride gas. In the etching step, the silicon-containing film is etched by the chemical species from the plasma. The flow rate of hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding the inert gas is 70% by volume or more and 96% by volume or less. According to this embodiment, by using plasma generated from the first processing gas in which the flow rate of hydrogen fluoride gas is 70% by volume or more and 96% by volume or less with respect to the total flow rate excluding the inert gas. , The selection ratio of etching of the film containing silicon to the etching of the mask is improved.

In one exemplary embodiment, the first treatment gas may include a carbon-containing gas and at least one selected from the group consisting of oxygen-containing gas, halogen-containing gas and phosphorus-containing gas.

In one exemplary embodiment, the carbon-containing gas may include at least one selected from the group consisting of fluorocarbon gases, hydrofluorocarbon gases, and hydrocarbon gases.

In one exemplary embodiment, the fluorocarbon gas is selected from the group consisting of _{CF 4} , C ₂ F ₂ , C ₂ F ₄ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ and C ₅ F _8. It may be at least one kind.

In one exemplary embodiment, the fluorocarbon gas can be a C ₄ F ₈ gas.

In one exemplary embodiment, the hydrofluorocarbon gas is CHF ₃ , CH ₂ F ₂ , CH ₃ F, C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F _2. , C ₃ HF ₇ , C ₃ H ₂ F ₂ , C ₃ H ₂ F ₆ , C ₃ H ₂ F ₄ , C ₃ H ₃ F ₅ , C ₄ H ₅ F ₅ , C ₄ H ₂ F ₆ , C ₅ It may be at least one selected from the group consisting of H ₂ F ₁₀ , c-C ₅ H ₃ F ₇ and C ₃ H ₂ F _4.

In one exemplary embodiment, the hydrofluorocarbon gas may be at least one selected from the group consisting of _{C 3} H ₂ F ₄ gas and C ₄ H ₂ F _{6 gas.}

In one exemplary embodiment, the hydrocarbon gas may be at least one selected from the group consisting of _{CH 4} , C ₂ H ₆ , C ₃ H ₆ , C ₃ H ₈ and C ₄ H _10.

In one exemplary embodiment, the carbon-containing gas may be a hydrofluorocarbon gas having 3 or more carbon atoms.

In one exemplary embodiment, the silicon-containing film comprises a group consisting of a laminated film including a silicon oxide film and a silicon nitride film, a polysilicon film, a low dielectric constant film, and a laminated film including a silicon oxide film and a polyether film. It may be at least one selected.

In one exemplary embodiment, the mask may be a carbon-containing mask or a metal-containing mask.

In one exemplary embodiment, a step of adjusting the temperature of the substrate support on which the substrate is placed to 0 ° C. or lower may be further included before the step of etching.

In another exemplary embodiment, a substrate processing method is provided. The substrate processing method includes a step of generating plasma from the precoat gas in the chamber of the plasma processing apparatus to form a precoat on the inner wall of the chamber. The plasma processing method further comprises the step of providing the substrate in the chamber. The substrate has a silicon-containing film containing a silicon oxide film and a mask provided on the silicon-containing film. The substrate processing method further includes a step of controlling the temperature of the substrate support on which the substrate is placed to 0 ° C. or lower. The substrate treatment method includes a step of etching a silicon-containing film with a plasma generated from a treatment gas containing at least one carbon-containing gas selected from the group consisting of hydrogen fluoride gas and fluorocarbon gas and hydrofluorocarbon gas. .. In the etching step, the silicon-containing film is etched by the chemical species from the plasma. The flow rate of hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding the inert gas is 70% by volume or more. The substrate processing method further comprises a step of generating plasma from the cleaning gas in the chamber to clean the inside of the chamber. According to this embodiment, the mask is etched by using plasma generated from the first processing gas in which the flow rate of hydrogen fluoride gas is 70% by volume or more with respect to the total flow rate excluding the inert gas. The selection ratio of etching of the film containing silicon to the gas is improved.

In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a plasma generation unit, and a control unit. The chamber has a gas supply port and a gas discharge port. The control unit is configured to execute a process including a step of arranging the substrate in the chamber, a step of controlling the temperature of the substrate support, and a step of etching. In the step of arranging the substrate in the chamber, the substrate having the silicon-containing film containing the silicon oxide film and the mask provided on the silicon-containing film is arranged on the substrate support. In the step of controlling the temperature of the substrate support, the temperature of the substrate support is controlled to 0 ° C. or lower. In the etching step, silicon is contained in the chamber by plasma generated from a first processing gas containing hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of fluorocarbon gas and hydrofluorocarbon gas. Etch the film. In the etching step, the control unit controls so that the flow rate of the hydrogen fluoride gas is the largest among the first processing gas excluding the inert gas.

Hereinafter, various exemplary embodiments will be described in detail with reference to the drawings. In addition, the same reference numerals are given to the same or corresponding parts in each drawing.

[First Embodiment]
FIG. 1 is a flowchart showing an example of a substrate processing method according to the first embodiment. The method MT1 shown in FIG. 1 is performed to etch a film containing silicon. Method MT1 can be used, for example, to manufacture a NAND flash memory having a three-dimensional structure. Method MT1 is performed using a plasma processing apparatus. FIG. 2 is a diagram schematically showing an example plasma processing apparatus. The method MT1 shown in FIG. 1 can be performed using the plasma processing apparatus 1 shown in FIG.

The plasma processing device 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein. The chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The chamber body 12 is made of, for example, aluminum. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. The film may be a ceramic such as aluminum oxide or yttrium oxide.

A passage 12p is formed on the side wall of the chamber body 12. The substrate W is conveyed between the internal space 10s and the outside of the chamber 10 through the passage 12p. The passage 12p is opened and closed by a gate valve 12g provided along the side wall of the chamber body 12.

A support portion 13 is provided on the bottom portion of the chamber body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a substantially cylindrical shape. The support portion 13 extends upward from the bottom of the chamber body 12 in the internal space 10s. The support portion 13 has a support base 14 at the upper portion. The support base 14 is configured to support the substrate W in the internal space 10s.

The support base 14 has a lower electrode 18 and an electrostatic chuck 20. The support 14 may further have an electrode plate 16. The electrode plate 16 is formed of a conductor such as aluminum and has a substantially disk shape. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a substantially disk shape. The lower electrode 18 is electrically connected to the electrode plate 16. The support base 14 is an example of a substrate support.

The electrostatic chuck 20 is provided on the lower electrode 18. The substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body and an electrode (chuck electrode). The main body of the electrostatic chuck 20 has a substantially disk shape and is formed of a dielectric. The chuck electrode of the electrostatic chuck 20 is a film-shaped electrode, and is provided in the main body of the electrostatic chuck 20. The chuck electrode of the electrostatic chuck 20 is connected to the DC power supply 20p via the switch 20s. When a voltage from the DC power supply 20p is applied to the chuck electrode of the electrostatic chuck 20, an electrostatic attractive force is generated between the electrostatic chuck 20 and the substrate W. The substrate W is held by the electrostatic chuck 20 by the electrostatic attraction. In addition to the chuck electrode described above, the electrostatic chuck 20 may have a bias electrode for drawing ions into the substrate W in the main body. The bias electrode may be a film-like electrode like the chuck electrode.

An edge ring 25 is arranged on the peripheral edge of the lower electrode 18 so as to surround the edge of the substrate W. The edge ring 25 improves the in-plane uniformity of the plasma treatment with respect to the substrate W. The edge ring 25 may be formed of silicon, silicon carbide, quartz or the like.

A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (for example, a refrigerant) is supplied to the flow path 18f from a chiller unit (not shown) provided outside the chamber 10 via a pipe 22a. The heat exchange medium supplied to the flow path 18f is returned to the chiller unit via the pipe 22b. In the plasma processing apparatus 1, the temperature of the substrate W placed on the electrostatic chuck 20 is adjusted by heat exchange between the heat exchange medium and the lower electrode 18.

The plasma processing apparatus 1 is provided with a gas supply line 24. The gas supply line 24 supplies heat transfer gas (for example, He gas) from the heat transfer gas supply mechanism between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the support base 14. The upper electrode 30 is supported on the upper part of the chamber body 12 via the member 32. The member 32 is formed of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the chamber body 12.

The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 is the lower surface on the side of the internal space 10s, and defines the internal space 10s. The top plate 34 can be formed of a low resistance conductor or semiconductor that generates less Joule heat. The top plate 34 has a plurality of gas discharge holes 34a that penetrate the top plate 34 in the plate thickness direction.

The support 36 supports the top plate 34 in a detachable manner. The support 36 is formed of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support 36. The support 36 has a plurality of gas holes 36b extending downward from the gas diffusion chamber 36a. The plurality of gas holes 36b communicate with the plurality of gas discharge holes 34a, respectively. The support 36 is formed with a gas supply port 36c. The gas supply port 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas supply port 36c.

A valve group 42, a flow rate controller group 44, and a gas source group 40 are connected to the gas supply pipe 38. The gas source group 40, the valve group 42, and the flow rate controller group 44 constitute a gas supply unit. The gas source group 40 includes a plurality of gas sources. The valve group 42 includes a plurality of open / close valves. The flow rate controller group 44 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers in the flow rate controller group 44 is a mass flow controller or a pressure control type flow rate controller. Each of the plurality of gas sources of the gas source group 40 is connected to the gas supply pipe 38 via the corresponding on-off valve of the valve group 42 and the corresponding flow rate controller of the flow rate controller group 44.

In the plasma processing apparatus 1, a shield 46 is detachably provided along the inner wall surface of the chamber body 12 and the outer periphery of the support portion 13. The shield 46 prevents reaction by-products from adhering to the chamber body 12. The shield 46 is configured, for example, by forming a corrosion-resistant film on the surface of a base material made of aluminum. The corrosion resistant film can be formed from a ceramic such as yttrium oxide.

A baffle plate 48 is provided between the support portion 13 and the side wall of the chamber body 12. The baffle plate 48 is configured, for example, by forming a corrosion-resistant film (a film such as yttrium oxide) on the surface of a base material made of aluminum. A plurality of through holes are formed in the baffle plate 48. A gas discharge port 12e is provided below the baffle plate 48 and at the bottom of the chamber body 12. An exhaust device 50 is connected to the gas discharge port 12e via an exhaust pipe 52. The exhaust device 50 includes a pressure regulating valve and a vacuum pump such as a turbo molecular pump.

The plasma processing apparatus 1 includes a first high frequency power supply 62 and a second high frequency power supply 64. The first high frequency power source 62 is a power source that generates the first high frequency power. The first high frequency power has a frequency suitable for plasma generation. The frequency of the first high frequency power is, for example, a frequency in the range of 27 MHz to 100 MHz. The first high frequency power may be a continuous wave or a pulse wave. The first high frequency power supply 62 is connected to the lower electrode 18 via the matching unit 66 and the electrode plate 16. The matching device 66 has a circuit for matching the output impedance of the first high frequency power supply 62 with the impedance on the load side (lower electrode 18 side). The first high frequency power supply 62 may be connected to the upper electrode 30 via the matching device 66. The first high frequency power supply 62 constitutes an example plasma generation unit.

The second high frequency power source 64 is a power source that generates the second high frequency power. The second high frequency power has a lower frequency than the frequency of the first high frequency power. When the second high frequency power is used together with the first high frequency power, the second high frequency power is used as the high frequency power for bias for drawing ions into the substrate W. The frequency of the second high frequency power is, for example, a frequency in the range of 400 kHz to 13.56 MHz. The second high frequency power may be a continuous wave or a pulse wave. The second high frequency power supply 64 is connected to the support base 14 via the matching unit 68. In one example, the second high frequency power supply 64 is connected to the lower electrode 18 via the matching unit 68 and the electrode plate 16. The matching device 68 has a circuit for matching the output impedance of the second high frequency power supply 64 with the impedance on the load side (lower electrode 18 side). The second high frequency power supply 64 may be connected to the bias electrode provided in the electrostatic chuck 20 via the matching unit 68 and the electrode plate 16 in the same manner as the bias power supply described later.

It should be noted that the plasma may be generated by using the second high frequency power without using the first high frequency power, that is, by using only a single high frequency power. In this case, the frequency of the second high frequency power may be a frequency larger than 13.56 MHz, for example, 40 MHz. The plasma processing device 1 does not have to include the first high frequency power supply 62 and the matching device 66. The second high frequency power supply 64 constitutes an example plasma generation unit.

Further, in the present disclosure, the plasma processing apparatus 1 may be configured to apply a DC voltage to the upper electrode 30 during plasma processing. For example, the plasma processing apparatus 1 may apply a pulsed negative DC voltage to the upper electrode 30.

In the plasma processing apparatus 1, gas is supplied from the gas supply unit to the internal space 10s to generate plasma. Further, by supplying the first high frequency power and / or the second high frequency power, a high frequency electric field is generated between the upper electrode 30 and the lower electrode 18. The generated high frequency electric field produces plasma.

The plasma processing device 1 may further include a control unit 80. The control unit 80 may be a computer including a processor, a storage unit such as a memory, an input device, a display device, a signal input / output interface, and the like. The control unit 80 controls each unit of the plasma processing device 1. In the control unit 80, the operator can perform a command input operation or the like in order to manage the plasma processing device 1 by using the input device. Further, the control unit 80 can visualize and display the operating status of the plasma processing device 1 by the display device. Further, a control program and recipe data are stored in the storage unit. The control program is executed by the processor in order to execute various processes in the plasma processing device 1. The processor executes a control program and controls each part of the plasma processing device 1 according to the recipe data.

See FIG. 1 again. In the following, the method MT1 will be described by taking the case where the plasma processing apparatus 1 is used in the execution as an example. As shown in FIG. 1, method MT1 includes step ST11. In step ST11, the substrate W is provided in the chamber 10 of the plasma processing apparatus. The substrate W is placed on the electrostatic chuck 20 and held by the electrostatic chuck 20.

FIG. 3 is a partially enlarged cross-sectional view of an example substrate provided in step ST11 of method MT1. The substrate W shown in FIG. 3 has a base layer UL, a film SF, and a mask MSK. The underlying layer UL can be a layer made of polycrystalline silicon. The film SF is provided on the base layer UL. The membrane SF contains silicon. The film SF can be a laminated film including one or more silicon oxide films and one or more silicon nitride films. In the example shown in FIG. 3, the film SF is a multilayer film including a plurality of silicon oxide films IL1 and a plurality of silicon nitride films IL2. The plurality of silicon oxide films IL1 and the plurality of silicon nitride films IL2 are laminated alternately. The film SF may be another single-layer film containing silicon or another multilayer film containing silicon. When the film SF is a single-layer film, the film SF may be, for example, a low dielectric constant film formed of SiOC, SiOF, SiCOH, or the like, or a polysilicon film. Alternatively, when the membrane SF is a multilayer film, the membrane SF can be, for example, a laminated film including one or more silicon oxide films and one or more polysilicon films.

The mask MSK is provided on the membrane SF. The mask MSK has a pattern for forming a space such as a hole in the film SF. The mask MSK can be, for example, a hard mask. The mask MSK can be, for example, a carbon-containing mask and / or a metal-containing mask. The carbon-containing mask is formed, for example, from at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. The metal-containing mask is formed from at least one selected from the group consisting of titanium nitride, titanium oxide, and tungsten. Alternatively, the mask MSK may be, for example, a boron-containing mask formed of silicon borohydride, boron nitride, boron carbide, or the like.

As shown in FIG. 1, method MT1 further comprises step ST12. Step ST12 is executed after step ST11. In step ST12, plasma is generated from the first processing gas in the chamber 10. In step ST12, the film SF is etched by the chemical species from this plasma.

The first processing gas used in step ST12 contains hydrogen fluoride gas. The flow rate of hydrogen fluoride gas is higher than the flow rate of other gases contained in the first processing gas excluding the inert gas. Specifically, the flow rate of the hydrogen fluoride gas in the step ST12 is 70% by volume or more, 80% by volume or more, 85% by volume or more, and 90% by volume with respect to the total flow rate of the first processing gas excluding the inert gas. % Or more or 95% by volume or more. From the viewpoint of suppressing the occurrence of shape abnormalities such as boeing in the membrane SF, when a carbon-containing gas or the like is added, the flow rate of the hydrogen fluoride gas is the total flow rate of the first treated gas excluding the inert gas. However, it may be less than 100% by volume, 99.5% by volume or less, 98% by volume or less, or 96% by volume or less. In one example, the flow rate of the hydrogen fluoride gas is adjusted to 70% by volume or more and 96% by volume or less with respect to the total flow rate of the first processing gas excluding the inert gas. By controlling the flow rate of the hydrogen fluoride gas in the first processing gas excluding the inert gas to such a range, it is possible to etch the film SF at a high etching rate while suppressing the etching of the mask MSK. can. As a result, the selection ratio of etching of the silicon-containing film to the etching of the mask can be set to 5 or more. Therefore, even in a process that requires a high aspect ratio such as a NAND flash memory having a three-dimensional structure, the film SF can be etched at an effective speed. Further, due to such a high selectivity, the amount of a depositary gas such as a carbon-containing gas can be suppressed, so that not only the risk of the mask MSK being clogged can be reduced, but also the risk of clogging of the mask MSK can be reduced, and as will be described later, the inside of the chamber 10 can be suppressed. The cleaning time can be reduced to 50% or less. As a result, the throughput of substrate processing can be significantly improved. On the other hand, when the flow rate of the hydrogen fluoride gas is equal to or less than the flow rate of the other gas contained in the first processing gas excluding the inert gas, the selection ratio may not be sufficiently improved. The total flow rate of the first processing gas excluding the inert gas may be appropriately adjusted according to the chamber volume, and in one example, it may be 100 sccm or more.

The first treatment gas may contain a carbon-containing gas in addition to the hydrogen fluoride gas. Further, in addition to the hydrogen fluoride gas and the carbon-containing gas, at least one selected from the group consisting of the oxygen-containing gas and the halogen-containing gas may be contained.

When the first treatment gas contains a carbon-containing gas, carbon-containing deposits are formed on the mask surface, so that the etching selectivity of the silicon-containing film with respect to the etching of the mask can be further improved. The carbon-containing gas includes, for example, at least one selected from the group consisting of fluorocarbon gas, hydrofluorocarbon gas, and hydrocarbon gas. As the fluorocarbon gas, for example, CF ₄ , C ₂ F ₂ , C ₂ F ₄ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ or C ₅ F ₈ can be used. Examples of the hydrofluorocarbon gas include CHF ₃ , CH ₂ F ₂ , CH ₃ F, C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F ₂ , C ₃ HF _7. , C ₃ H ₂ F ₂ , C ₃ H ₂ F ₆ , C ₃ H ₂ F ₄ , C ₃ H ₃ F ₅ , C ₄ H ₅ F ₅ , C ₄ H ₂ F ₆ , C ₅ H ₂ F ₁₀ , c-C ₅ H ₃ F ₇ or C ₃ H ₂ F ₄ can be used. As the hydrocarbon gas, for example, CH ₄ , C ₂ H ₆ , C ₃ H ₆ , C ₃ H ₈ or C ₄ H ₁₀ can be used. The carbon-containing gas may contain CO and / or CO ₂ in addition to the above. In one example, as the carbon-containing gas, a fluorocarbon gas having two or more carbon atoms and / or a hydrofluorocarbon gas can be used. When a fluorocarbon gas and / or a hydrofluorocarbon gas having 2 or more carbon atoms is used, shape abnormalities such as Boeing can be effectively suppressed. By using a fluorocarbon gas and / or a hydrofluorocarbon gas having 3 or more carbon atoms, the shape abnormality can be further suppressed. The 3 or more fluorocarbon gases carbon atoms, for example, may be used C ₄ F _8. The hydrofluorocarbon gas having 3 or more carbon atoms may contain an unsaturated bond or may contain _{3 CF groups having 1 or more carbon atoms.} As the hydrofluorocarbon gas having 3 or more carbon atoms, for example, C ₃ H ₂ F ₄ or C ₄ H ₂ F ₆ can be used.

When the first processing gas contains an oxygen-containing gas, it is possible to suppress blockage of the mask during etching. As the oxygen-containing gas, for example, at least one selected from the group consisting of _{O 2} , CO, CO ₂ , H ₂ O or H ₂ O _{2 can be used.}

When the first processing gas contains a halogen-containing gas, the etching shape can be controlled. Examples of the halogen-containing gas include SF ₆ , NF ₃ , XeF ₂ , SiF ₄ , IF ₇ , ClF ₅ , BrF ₅ , AsF ₅ , NF ₅ , PF ₃ , PF ₅ , POF ₃ , BF ₃ , HPF ₆ . fluorine containing gas containing no carbon of WF _{6, etc., Cl 2, SiCl 2, SiCl} 4, CCl 4, BCl 3, PCl 3, PCl 5, POCl 3 or the like chlorine-containing _{gas, HBr, CBr 2 F 2,} C 2 Bromine-containing gas such as F ₅ Br, PBr ₃ , PBr ₅ , POBr _{3 , HI, CF 3} I, C ₂ F ₅ I, C ₃ F ₇ I, IF ₅ , IF ₇ , I ₂ , PI _{3 and the} like iodine At least one selected from the group consisting of contained gases can be used.

In addition to the above, the first treatment gas is a gas having a side wall protection effect, for example, a sulfur-containing gas such as COS, P ₄ O ₁₀ , P ₄ O ₈ , P ₄ O ₆ , PH ₃ , Ca ₃ P ₂ , and so on. It may contain a phosphorus-containing gas such as _{H 3} PO ₄ and Na ₃ PO ₄ , and a boron-containing gas such as _{B 2} H _6. The phosphorus-containing gas having a side wall protective effect also includes the above-mentioned fluorophosphorus gas such as _{PF 3} and PF ₅ , and halogenated phosphorus gas containing chloride phosphorus gas such as PCl ₃ and _{PCl 5.}

In the exemplary embodiment of the present disclosure, the first treatment gas comprises hydrogen fluoride and at least one carbon-containing gas selected from the group consisting of fluorocarbon gas and hydrofluorocarbon gas. The carbon-containing gas may be the above-mentioned fluorocarbon gas or the above-mentioned hydrofluorocarbon gas. The fluorocarbon gas may be _{C 4} F _8. Further, the hydrofluorocarbon gas may be at least one selected from the group consisting of _{C 3} H ₂ F ₄ and C ₄ H ₂ F _6.

In an exemplary embodiment, the first treatment gas may further comprise at least one selected from the group consisting of oxygen-containing gas and halogen-containing gas. In this case, the halogen-containing gas may be at least one selected from the group consisting of a halogen-containing gas containing a halogen element other than fluorine and a carbon-free fluorine-containing gas.

In the exemplary embodiment, the additive gas may further contain at least one selected from the group consisting of sulfur-containing gas, phosphorus-containing gas and boron-containing gas having a side wall protective effect.

In addition to these gas species, the first treatment gas may contain an inert gas. As the inert gas, in addition to nitrogen gas, noble gases such as Ar, Kr and Xe can be used. However, the first processing gas is controlled so that the flow rate of the hydrogen fluoride gas is the ratio described above with respect to the total flow rate of the first processing gas excluding these inert gases.

For the execution of the step ST12, the control unit 80 controls the gas supply unit so as to supply the above-mentioned processing gas into the chamber 10. For the execution of the step ST12, the control unit 80 controls the gas supply unit so that the flow rate of the hydrogen fluoride gas in the processing gas supplied into the chamber 10 is 70% by volume or more of the total flow rate of the processing gas. do. For the execution of step ST12, the control unit 80 controls the exhaust device 50 so that the pressure in the chamber 10 becomes the specified pressure. For the execution of step ST12, the control unit 80 supplies a first high frequency power and / or a second high frequency power to generate plasma from the processing gas in the chamber 10. And / or control the second high frequency power supply 64.

In step ST12, the second high-frequency power source 64 supplies a second high-frequency power of 5 W / cm ² or more (that is, high-frequency power for bias) to the support base 14 in order to draw ions from the plasma into the substrate W. You may. A second high frequency power of 5 W / cm ² or more allows ions from the plasma to sufficiently reach the bottom of the space of the membrane SF formed by etching (eg, the space SP shown in FIG. 4).

Instead of the high frequency power for bias, a pulse voltage other than the high frequency may be supplied to the support base 14. Here, the pulse voltage is a pulse-shaped voltage supplied from the pulse power supply. The pulse power supply may be configured such that the power supply itself supplies a pulse wave, or may be provided with a device for pulsing a voltage on the downstream side of the pulse power supply. In one example, the pulse voltage is supplied to the support 14 so that a negative potential is generated on the substrate W. The pulse voltage may be a negative DC voltage pulse. Further, the pulse voltage may be a square wave pulse, a triangular wave pulse, an impulse pulse, or a pulse having another voltage waveform.

FIG. 5 shows an example of a timing chart relating to the substrate processing method of the exemplary embodiment. In FIG. 5, the horizontal axis represents time. In FIG. 5, the vertical axis shows the supply state of the first processing gas, the level of the first high frequency power HF, and the level of the pulse voltage. In FIG. 5, the first processing gas is periodically supplied into the chamber 10. Further, the pulse of the first high frequency power and the pulse voltage are periodically supplied to the support base 14. Further, the period in which the pulse of the first high frequency power HF is supplied, the period in which the pulse voltage is supplied, and the period in which the first processing gas is supplied are synchronized. The first processing gas may be continuously supplied into the chamber 10.

In FIG. 5, the “L” level of the first high frequency power HF is the power level at which the first high frequency power HF is not supplied or the power level of the first high frequency power HF is indicated by “H”. Shows that it is lower than. The "L" level of the pulse voltage indicates that no pulse voltage is applied to the support base 14 or that the level of the pulse voltage is lower than the level indicated by "H". Further, "ON" in the supply state of the first processing gas indicates that the first processing gas is supplied into the chamber 10, and "OFF" in the supply state of the first processing gas is It shows that the supply of the first processing gas into the chamber 10 is stopped. Here, the period in which the voltage level of the pulse voltage is L is referred to as “L period”, and the period in which the voltage level of the pulse voltage is H is referred to as “H period”.

The frequency of the pulse voltage (first frequency) in the H period may be controlled to 100 kHz to 3.2 MHz. In one example, the first frequency is controlled to 400 kHz. Further, in this case, the duty ratio (first duty ratio) indicating the ratio of the period during which the pulse voltage level becomes H in one cycle may be 50% or less, or may be 30% or less.

Further, the frequency of the pulse voltage supplied periodically, that is, the frequency defining the period of the H period (second frequency) may be 1 kHz to 200 kHz or 5 Hz to 100 kHz. Further, in this case, the duty ratio (second duty ratio) indicating the ratio of the H period in one cycle may be 50% to 90%.

In the exemplary embodiment, the case where the period in which the pulse of the first high frequency power HF is supplied, the period in which the pulse voltage is supplied, and the period in which the first processing gas is supplied are synchronized has been described. , These do not have to be synchronized.

The temperature of the electrostatic chuck 20 in the step ST12 is not particularly limited. However, by adjusting the temperature of the electrostatic chuck 20 to a low temperature, for example, 0 ° C. or lower or −50 ° C. or lower before the start of the step ST12, the adsorption of the etchant on the substrate surface is promoted, so that the etching rate is improved. be able to. When the first processing gas contains a phosphorus-containing gas, the temperature of the electrostatic chuck 20 is 50 ° C. or lower, 30 ° C. or lower, or 20 ° C. depending on the ratio of the phosphorus-containing gas in the first processing gas. It may be as follows.

When the execution of the step ST12 is completed, the method MT1 is completed. FIG. 4 is a partially enlarged cross-sectional view of an example substrate after executing the substrate processing method shown in FIG. By executing the method MT1, as shown in FIG. 4, a space SP reaching, for example, the underlying layer UL is formed in the film SF.

(Experiment 1)
Hereinafter, the results of Experiment 1 performed for the evaluation of Method MT1 will be described. In Experiment 1, eight sample substrates same as the substrate W shown in FIG. 3 were prepared. In Experiment 1, plasma etching of the film SF of eight sample substrates was performed using the plasma processing apparatus 1. In plasma etching, a first treatment gas containing a fluorocarbon gas, a hydrofluorocarbon gas, a carbon-free fluorine-containing gas and a halogen-containing gas was used. Of the eight sample substrates, the first processing gas used for plasma etching of the first sample substrate did not contain hydrogen fluoride gas. In the first processing gas used for plasma etching of the second to eighth sample substrates among the eight sample substrates, the flow rate of the hydrogen fluoride gas with respect to the total flow rate of the first processing gas was 34.2% by volume, respectively. It was 51.0% by volume, 80.0% by volume, 95.2% by volume, 98.8% by volume, 99.5% by volume, and 100% by volume. In Experiment 1, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to a temperature of −50 ° C. or lower before the start of plasma etching.

In Experiment 1, the selection ratio of the etching of the film SF to the etching of the mask MSK was obtained from the results of plasma etching of the film SF of the eight sample substrates. Specifically, the selection ratio was obtained by dividing the etching rate of the film SF by the etching rate of the mask MSK from the results of plasma etching of the film SF of the eight sample substrates.

FIG. 6 is a graph showing the results of Experiment 1 performed for the evaluation of the substrate processing method shown in FIG. In the graph of FIG. 6, the horizontal axis indicates the flow rate ratio. The flow rate ratio is the ratio (% by volume) of the flow rate of hydrogen fluoride gas to the total flow rate of the first processing gas excluding the inert gas. In the graph of FIG. 6, the vertical axis indicates the selection ratio. In FIG. 6, reference numerals P1 to P8 indicate selection ratios obtained from the results of plasma etching of the film SF of the first to eighth sample substrates.

As shown in FIG. 6, as a result of Experiment 1, the selection ratio is the ratio of the flow rate of hydrogen fluoride gas to the total flow rate of the first processing gas excluding the inert gas (hereinafter referred to as “flow rate ratio”). It was confirmed that it increased with the increase. In particular, in the region where the flow rate ratio is 80% by volume or more, it is confirmed that the increase rate of the selection ratio is large (the slope of the graph in FIG. 6 is large) as compared with the region where the flow rate ratio is less than 80% by volume. The reason for this is considered as follows. In the region where the flow rate ratio is less than 80% by volume, the etching rate of the silicon-containing film increases as the flow rate ratio increases, thereby increasing the selection ratio. However, in this region, since a certain amount of mask is also etched, the increase in selection ratio is relatively gradual. On the other hand, in the region where the flow rate ratio is 80% by volume or more, the etching rate of the silicon-containing film tends to be saturated, but the etching rate of the mask decreases, which increases the selection ratio. That is, in the region where the flow rate ratio is 80% by volume or more, the silicon-containing film is etched while maintaining a high etching rate, while the mask is hardly etched, so that the rate of increase in the selection ratio is large.

Further, from FIG. 6, it can be seen that when the flow rate of the hydrogen fluoride gas occupies 70% by volume or more in the total flow rate of the first processing gas excluding the inert gas, a selection ratio of 5 or more can be obtained. In particular, when the flow rate of hydrogen fluoride gas occupies 90% by volume or more in the total flow rate of the first processing gas excluding the inert gas, the selection ratio of 7 or more occupies 95% by volume or more. It can be seen that a selection ratio of 7.5 or more can be obtained.

(Experiment 2)
In Experiment 2, the same three sample substrates as the substrate W shown in FIG. 3 were prepared. In Experiment 2, plasma etching of the film SF of the three sample substrates was performed using the plasma processing apparatus 1. In plasma etching, a first treatment gas containing hydrogen fluoride gas and a carbon-containing gas was used. For the ninth sample substrate, a first treatment gas containing hydrogen fluoride gas and fluorocarbon gas was used. For the tenth sample substrate, a first treatment gas containing hydrogen fluoride gas and a hydrofluorocarbon gas having one carbon atom was used. For the eleventh sample substrate, a first treatment gas containing hydrogen fluoride gas and a hydrofluorocarbon gas having 4 carbon atoms was used. In Experiment 2, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to a temperature of −50 ° C. or lower before the start of plasma etching.

In Experiment 2, the selection ratio of the etching of the film SF to the etching of the mask MSK was obtained from the results of plasma etching of the film SF of the three sample substrates. Specifically, the selection ratio was obtained by dividing the etching rate of the film SF by the etching rate of the mask MSK from the results of plasma etching of the film SF of the three sample substrates.

FIG. 7 is a graph showing the results of Experiment 2. In the graph of FIG. 7, the horizontal axis indicates the sample substrate. In the graph of FIG. 7, the vertical axis indicates the selection ratio. In FIG. 7, reference numeral Sub. Reference numerals 9 to 11 indicate the selection ratios obtained from the results of plasma etching of the film SF of the 9th to 11th sample substrates.

As shown in FIG. 7, as a result of Experiment 2, it was confirmed that the selection ratio was 6 or more in any of the sample substrates. In particular, it was confirmed that the selection ratio was about 14 in the eleventh sample substrate using the hydrofluorocarbon gas having 4 carbon atoms, and the selectivity was the highest among the three sample substrates.

(Experiment 3 and Experiment 4)
In Experiment 3, plasma was generated from a processing gas which is a mixed gas of hydrogen fluoride gas and argon gas, and a silicon oxide film was etched by using the plasma processing apparatus 1. In Experiment 4, a plasma processing apparatus 1 was used to generate plasma from a processing gas which is a mixed gas of _{hydrogen fluoride gas, argon gas, and PF 3 gas, and etch the silicon oxide film.} In Experiments 3 and 4, the silicon oxide film was etched while changing the temperature of the electrostatic chuck 20. In Experiments 3 and 4, the amount of hydrogen fluoride (HF) and the amount of SiF ₃ in the gas phase during etching of the silicon oxide film were measured using a quadrupole mass spectrometer. 8 (a) and 8 (b) show the results of Experiment 3 and Experiment 4. FIG. 8A shows the relationship between the temperature of the electrostatic chuck 20 and the amount of hydrogen fluoride (HF) and the amount of SiF _{3 at the time of etching the silicon oxide film in Experiment 3.} Further, FIG. 8B shows the relationship between the temperature of the electrostatic chuck 20 and the amount of hydrogen fluoride (HF) and the amount of SiF _{3 at the time of etching the silicon oxide film in Experiment 4.}

As shown in FIG. 8A, in Experiment 3, when the temperature of the electrostatic chuck 20 is about -60 ° C. or lower, the amount of hydrogen fluoride (HF) which is an etchant decreases and silicon oxidation occurs. The amount of _{SiF 3} , which is a reaction product produced by etching the film, was increased. That is, in Experiment 3, when the temperature of the electrostatic chuck 20 was about −60 ° C. or lower, the amount of etchant used in etching the silicon oxide film increased. On the other hand, as shown in FIG. 8B, in Experiment 4, when the temperature of the electrostatic chuck 20 is 20 ° C. or lower, the amount of hydrogen fluoride (HF) decreases and the amount of _{SiF 3 increases.} It was increasing. That is, in Experiment 4, when the temperature of the electrostatic chuck 20 was 20 ° C. or lower, the amount of etchant used in etching the silicon oxide film increased. The processing gas used in Experiment 4 is different from the processing gas used in Experiment 3 in that it contains _{PF 3 gas.} In Experiment 4, when the silicon oxide film was etched, a state in which phosphorus chemical species were present on the surface of the silicon oxide film was formed. From this, in the state where the phosphorus chemical species is present on the surface of the silicon oxide film, the adsorption of the etchant to the silicon oxide film is promoted even if the temperature of the electrostatic chuck 20 is a relatively high temperature of 20 ° C. or less. I can understand that. From this, it was confirmed that in the state where the phosphorus chemical species are present on the surface of the substrate, the supply of the etchant to the bottom of the opening (recess) is promoted and the etching rate of the silicon-containing film is increased.

[Second Embodiment]
In the substrate processing method according to the first embodiment, as the number of treatments increases, the amount of reaction products adhering to the inner wall of the chamber 10, the support base 14, and the like increases. When the amount of the reaction product adhered increases, the treatment environment changes, so that the uniformity of the treatment between the substrates W may deteriorate. In addition, an increase in the amount of adhesion of the reaction product becomes a factor in generating particles. Therefore, the inside of the chamber is cleaned by plasma obtained by turning the cleaning gas into plasma.

FIG. 9 is a flowchart showing an example of the substrate processing method according to the second embodiment. The method MT2 shown in FIG. 9 is performed to etch the silicon-containing film in the same manner as the method MT1. Since the process ST21 and the process ST22 are the same as the process ST11 and the process ST12 of the method MT1 described above, the description thereof is omitted here.

As shown in FIG. 9, method MT2 further comprises step ST23. Step ST23 is executed after step ST22. In step ST23, plasma is generated from the second processing gas (cleaning gas) in the chamber 10. In step ST23, the inside of the chamber 10 is cleaned by the chemical species from this plasma. The processing time of step 23 is usually determined by monitoring the emission state of the plasma. According to the second embodiment, the cleaning time can be shortened to 50% or less and the throughput of substrate processing can be improved as compared with the prior art.

The second processing gas used in step ST23 may contain, for example, at least one selected from the group consisting of a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas. As the fluorine-containing gas, for example, CF ₄ , SF ₆ or NF ₃ can be used. As the oxygen-containing gas, for example, O ₂ , CO, CO ₂ , H ₂ O or H ₂ O ₂ can be used. As the hydrogen-containing gas, for example, H ₂ or HCl can be used. As the nitrogen-containing gas, for example, N ₂ can be used. In addition to the above, the second treatment gas may contain a rare gas such as Ar.

The step ST23 may be executed every time one substrate W is processed, or may be executed after processing a predetermined number of substrates W or a predetermined number of lots of substrates W. Alternatively, it may be executed after the substrate processing for a predetermined time.

[Third Embodiment]
In both the first embodiment and the second embodiment, the first processing gas contains hydrogen fluoride gas. Since hydrogen fluoride gas is a highly corrosive gas, it is preferable to form a precoat on the inner wall of the chamber 10 before the etching step. In particular, when hydrogen fluoride gas is used at a high concentration, the maintenance frequency can be reduced by forming a precoat on the inner wall of the chamber 10 and suppressing corrosion of the inner wall of the chamber 10. Here, the inner wall of the chamber 10 includes a side wall and a ceiling of the chamber 10 (top plate 34 of the upper electrode 30), a support base 14, and the like.

The precoat film may be formed of a silicon-containing film such as a silicon oxide film, or a material of the same type as the material of the mask MSK. When the mask MSK is a carbon-containing mask, the precoat may be formed of a carbon-containing material. The carbon-containing material includes, for example, at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. When the mask MSK is a boron-containing mask, the precoat may be formed of a boron-containing material. As the boron-containing material, the boron-containing material includes, for example, at least one selected from the group consisting of silicon borohydride, boron nitride, and boron carbide.

FIG. 10 is a flowchart showing an example of the substrate processing method according to the third embodiment. The method MT3 shown in FIG. 10 is performed to etch the silicon-containing film in the same manner as the method MT1. Since the process ST31 and the process ST32 are the same as the process ST11 and the process ST12 of the method MT1 described above, the description thereof is omitted here.

As shown in FIG. 10, method MT2 further comprises step ST30. Step ST30 is executed before step ST31. In step ST30, plasma is generated from the third processing gas (precoat gas) in the chamber 10. In step ST30, the chemical species from this plasma form a precoat on the inner wall of chamber 10.

The precoat can be formed by Chemical Vapor Deposition (CVD) or Atomic Layer Deposition (ALD) using a third treatment gas. For example, the case of forming a silicon oxide film as a pre-coating, it is possible to use a silicon-containing gas such as SiCl ₄ and aminosilane-based gas as the third process gas, an oxygen-containing gas or the like such as O _2. When a carbon film is formed as the precoat, a carbon-containing gas such _{as CH 4} or C ₂ H _{2 can be used as the third treatment gas.}

The step ST33 may be executed every time one substrate W is processed, or may be executed after processing a predetermined number of substrates W or a predetermined number of lots of substrates W. Alternatively, it may be executed after the substrate processing for a predetermined time.

The step of forming the precoat may be performed in combination with the cleaning step as shown in another example of the substrate processing method according to the third embodiment of FIG. As a result, the generation of particles and the corrosion of the inner wall of the chamber 10 can be suppressed at the same time.

Although various exemplary embodiments have been described above, various omissions, substitutions, and changes may be made without being limited to the above-mentioned exemplary embodiments. It is also possible to combine elements from different exemplary embodiments to form other exemplary embodiments.

For example, the plasma processing apparatus used in the methods MT1 to MT4 may be a plasma processing apparatus different from the plasma processing apparatus 1. The plasma processing apparatus used in Methods MT1 to MT4 may be another capacitively coupled plasma processing apparatus, an inductively coupled plasma processing apparatus, or a plasma processing apparatus that generates plasma using a surface wave such as a microwave. good.

Further, as described above, hydrogen fluoride gas is a highly corrosive gas. Therefore, the flow rate ratio of the hydrogen fluoride gas and the type of gas added to the first treatment gas may be changed according to the treatment stage. In one example, at the end of etching where it is not necessary to maintain the thickness of the mask, the flow rate ratio of hydrogen fluoride gas may be lower than in the early to middle stages of etching where it is necessary to maintain the thickness of the mask. In another example, in etching in a low aspect ratio region where shape abnormalities such as Boeing are likely to occur, the flow rate ratio of the gas having a side wall protection effect may be increased as compared with etching in a high aspect ratio region. Further, the shape after etching may be monitored by an optical observation device or the like, and the flow rate ratio of hydrogen fluoride gas, the type or flow rate ratio of the gas added to the first processing gas may be changed according to the shape. good.

In addition, the disclosed embodiments further include the following aspects.

(Appendix 1)
A step of providing a silicon-containing film containing a silicon oxide film and a substrate having a mask on the silicon-containing film in the chamber.
A step of controlling the temperature of the substrate support on which the substrate is placed to 0 ° C. or lower, and
A first containing hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of _{C 4} F ₈ gas, C ₃ H ₂ F ₄ gas and C ₄ H ₂ F _{6 gas in the chamber.} The step of etching the silicon-containing film with the plasma generated from the processing gas of
Including
Among the first treated gases excluding the inert gas, the hydrogen fluoride gas has the highest flow rate.
Board processing method.

(Appendix 2)
The substrate treatment method according to (Appendix 1), wherein the first treatment gas further contains at least one additive gas selected from the group consisting of an oxygen-containing gas, a halogen-containing gas, and a phosphorus-containing gas.

(Appendix 3)
The flow rate of the hydrogen fluoride gas contains at least one carbon-containing gas selected from the group consisting of hydrogen fluoride gas and fluorocarbon gas and hydrofluorocarbon gas, and the flow rate of the hydrogen fluoride gas is 70% by volume or more with respect to the total flow rate excluding the inert gas. Is an etching gas composition.

(Appendix 4)
The fluorocarbon gas is at least one selected from the group consisting of _{CF 4} , C ₂ F ₂ , C ₂ F ₄ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ and C ₅ F _8. Etching gas composition in (Appendix 3).

(Appendix 5)
The fluorocarbon gas _is C 4 _{F 8} gas, the etching gas composition according to (Note 3).

(Appendix 6)
The hydrofluorocarbon gas is CHF ₃ , CH ₂ F ₂ , CH ₃ F, C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F ₂ , C ₃ HF ₇ , C. ₃ H ₂ F ₂ , C ₃ H ₂ F ₆ , C ₃ H ₂ F ₄ , C ₃ H ₃ F ₅ , C ₄ H ₅ F ₅ , C ₄ H ₂ F ₆ , C ₅ H ₂ F ₁₀ , c- The etching gas composition according to (Appendix 3), which is at least one selected from the group consisting of C ₅ H ₃ F ₇ and C ₃ H ₂ F _4.

(Appendix 7)
The etching gas composition according to (Appendix 3), wherein the hydrofluorocarbon gas is _{at least one selected from the group consisting of C 3} H ₂ F ₄ gas and C ₄ H ₂ F _{6 gas.}

(Appendix 8)
The etching gas composition according to any one of (Appendix 3) to (Appendix 7), further comprising at least one selected from the group consisting of an oxygen-containing gas and a halogen-containing gas.

(Appendix 9)
The etching gas composition according to any one of (Appendix 3) to (Appendix 8), further comprising at least one selected from the group consisting of a phosphorus-containing gas, a sulfur-containing gas and a boron-containing gas.

(Appendix 10)
The etching gas composition according to any one of (Appendix 3) to (Appendix 9), wherein the flow rate of the hydrogen fluoride gas is 96% by volume or less with respect to the total flow rate excluding the inert gas.

(Appendix 11)
Hydrogen fluoride gas for use in the etching gas composition according to any one of (Appendix 3) to (Appendix 10).

From the above description, it is understood that the various exemplary embodiments of the present disclosure are described herein for purposes of explanation and that various modifications can be made without departing from the scope and gist of the present disclosure. Will be done. Accordingly, the various exemplary embodiments disclosed herein are not intended to be limiting, and the true scope and gist is set forth by the appended claims.

1 ... Plasma processing device, 10 ... Chamber, W ... Substrate, SF ... Membrane, MSK ... Mask.

Claims (27)

A step of providing a substrate having a silicon-containing film containing a silicon oxide film and a mask on the silicon-containing film in the chamber.
A step of controlling the temperature of the substrate support on which the substrate is placed to 0 ° C. or lower, and
A step of etching the silicon-containing film with a plasma generated from a first treatment gas containing at least one carbon-containing gas selected from the group consisting of hydrogen fluoride gas and fluorocarbon gas and hydrofluorocarbon gas.
Including
Among the first treated gases excluding the inert gas, the hydrogen fluoride gas has the highest flow rate.
Board processing method. The substrate processing method according to claim 1, wherein the flow rate of the hydrogen fluoride gas is 70% by volume or more with respect to the total flow rate of the first processing gas excluding the inert gas. The fluorocarbon gas is at least one selected from the group consisting of _{CF 4} , C ₂ F ₂ , C ₂ F ₄ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ and C ₅ F _8. The substrate processing method according to claim 1 or 2. The fluorocarbon gas is C ₄ F ₈ gas, a substrate processing method according to claim 1 or 2. The hydrofluorocarbon gas is CHF ₃ , CH ₂ F ₂ , CH ₃ F, C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F ₂ , C ₃ HF ₇ , C. ₃ H ₂ F ₂ , C ₃ H ₂ F ₆ , C ₃ H ₂ F ₄ , C ₃ H ₃ F ₅ , C ₄ H ₅ F ₅ , C ₄ H ₂ F ₆ , C ₅ H ₂ F ₁₀ , c- The substrate processing method according to claim 1 or 2, which is at least one selected from the group consisting of C ₅ H ₃ F ₇ and C ₃ H ₂ F _4. The substrate treatment method according to claim 1 or 2, wherein the hydrofluorocarbon gas is _{at least one selected from the group consisting of C 3} H ₂ F ₄ gas and C ₄ H ₂ F _{6 gas.} The substrate processing method according to any one of claims 1 to 6, wherein the first processing gas further contains at least one selected from the group consisting of an oxygen-containing gas and a halogen-containing gas. The substrate treatment method according to any one of claims 1 to 7, wherein the first treatment gas further comprises at least one selected from the group consisting of a phosphorus-containing gas, a sulfur-containing gas, and a boron-containing gas. The substrate processing method according to any one of claims 1 to 8, wherein the flow rate of the hydrogen fluoride gas is 96% by volume or less with respect to the total flow rate of the first processing gas excluding the inert gas. The silicon-containing film is at least one selected from the group consisting of a silicon oxide film, a laminated film containing a silicon oxide film and a silicon nitride film, and a laminated film including a silicon oxide film and a polysilicon film, claim 1 to 1. 9. The substrate processing method according to any one of 9. The substrate processing method according to any one of claims 1 to 10, wherein the mask is a carbon-containing mask or a metal-containing mask. The substrate treatment method according to claim 11, wherein the carbon-containing mask is formed from at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. The substrate processing method according to any one of claims 1 to 12, further comprising a step of generating plasma from the second processing gas in the chamber and cleaning the inside of the chamber. The substrate processing method according to claim 13, wherein the second processing gas contains at least one selected from the group consisting of a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas. Any one of claims 1-14, further comprising the step of generating plasma from a third processing gas in the chamber to form a precoat on the inner wall of the chamber prior to the step of providing the substrate. The substrate processing method described in 1. The substrate processing method according to claim 15, wherein the third processing gas contains a carbon-containing gas. A step of providing a silicon-containing film and a substrate having a mask on the silicon-containing film in the chamber.
The step of etching the silicon-containing film with the plasma generated from the first processing gas containing hydrogen fluoride gas, and
Including
The flow rate of the hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding the inert gas is 70% by volume or more and 96% by volume or less.
Board processing method. The substrate processing method according to claim 17, wherein the first processing gas comprises at least one selected from the group consisting of a carbon-containing gas and an oxygen-containing gas and a halogen-containing gas. The substrate treatment method according to claim 18, wherein the carbon-containing gas comprises at least one selected from the group consisting of fluorocarbon gas, hydrofluorocarbon gas, and hydrocarbon gas. The fluorocarbon gas is at least one selected from the group consisting of _{CF 4} , C ₂ F ₂ , C ₂ F ₄ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ and C ₅ F _8. The substrate processing method according to claim 19. The hydrofluorocarbon gas is CHF ₃ , CH ₂ F ₂ , CH ₃ F, C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F ₂ , C ₃ HF ₇ , C. ₃ H ₂ F ₂ , C ₃ H ₂ F ₆ , C ₃ H ₂ F ₄ , C ₃ H ₃ F ₅ , C ₄ H ₅ F ₅ , C ₄ H ₂ F ₆ , C ₅ H ₂ F ₁₀ , c- The substrate processing method according to claim 19, which is at least one selected from the group consisting of C ₅ H ₃ F ₇ and C ₃ H ₂ F _4. The substrate treatment method according to claim 19, wherein the hydrocarbon gas is _{at least one selected from the group consisting of CH 4} , C ₂ H ₆ , C ₃ H ₆ , C ₃ H ₈ and C ₄ H _10. .. The substrate processing method according to claim 18, wherein the carbon-containing gas is a hydrofluorocarbon gas having 3 or more carbon atoms. The silicon-containing film is at least one selected from the group consisting of a laminated film containing a silicon oxide film and a silicon nitride film, a polysilicon film, a low dielectric constant film, and a laminated film including a silicon oxide film and a polysilicon film. , The substrate processing method according to any one of claims 17 to 23. The substrate processing method according to any one of claims 17 to 24, wherein the mask is a carbon-containing mask or a metal-containing mask. The substrate processing method according to any one of claims 17 to 25, further comprising a step of adjusting the temperature of the substrate support on which the substrate is placed to 0 ° C. or lower before the etching step. A chamber with a gas supply port and a gas discharge port,
Plasma generator and
Control unit and
Is a plasma processing device including
The control unit
A step of arranging a substrate having a silicon-containing film containing a silicon oxide film and a carbon-containing mask provided on the silicon-containing film in the chamber.
A step of controlling the temperature of the substrate support on which the substrate is placed to 0 ° C. or lower, and
A step of etching the silicon-containing film with a plasma generated from a first treatment gas containing at least one carbon-containing gas selected from the group consisting of hydrogen fluoride gas and fluorocarbon gas and hydrofluorocarbon gas.
Executes the process including
In the etching step, the flow rate of the hydrogen fluoride gas is controlled to be the largest among the first processing gas excluding the inert gas.
Plasma processing equipment.

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