Etching method and plasma processing apparatus

Abstract

A technique is provided for increasing the selectivity of etching a silicon-containing film relative to etching a mask in plasma etching. The disclosed etching method includes (a) providing a substrate in a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film. The etching method further includes (b) etching the silicon-containing film with chemical species from a plasma generated in the chamber from a process gas. The process gas includes hydrogen fluoride gas and a phosphorus-containing gas.

Description

[Technical field]

[0001] Exemplary embodiments of the present disclosure relate to etching methods, process gases, and plasma processing apparatus. [Background technology]

[0002] In the manufacture of electronic devices, plasma etching of a silicon-containing film on a substrate is performed. In the plasma etching, the silicon-containing film is etched using plasma generated from a processing gas. U.S. Patent Application Publication No. 2016 / 0343580 discloses a processing gas containing a fluorocarbon gas as a processing gas used in the plasma etching of a silicon-containing film. Japanese Patent Application Laid-Open No. 2016-39310 discloses a processing gas containing a hydrocarbon gas and a hydrofluorocarbon gas as a processing gas used in the plasma etching of a silicon-containing film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2016 / 0343580 [Patent Document 2] JP 2016-39310 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for increasing the selectivity of etching a silicon-containing film relative to etching a mask in a plasma etch. [Means for solving the problem]

[0005] In one exemplary embodiment, an etching method is provided. The etching method includes the step (a) of providing a substrate in a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film. The etching method further includes the step (b) of etching the silicon-containing film with chemical species from a plasma generated in the chamber from a process gas. The process gas includes a hydrogen fluoride gas and a phosphorus-containing gas. Effect of the Invention

[0006] According to one exemplary embodiment, it is possible to increase the selectivity of etching a silicon-containing film relative to etching a mask in a plasma etch. [Brief description of the drawings]

[0007] [Figure 1] 1 is a flow diagram of an etching method according to an exemplary embodiment. [Diagram 2] 2 is a partially enlarged cross-sectional view of an example of a substrate to which the etching method shown in FIG. 1 can be applied. [Diagram 3] 1 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment; [Figure 4] 2 is a partially enlarged cross-sectional view of an example of a substrate to which the etching method shown in FIG. 1 is applied. [Diagram 5] 4 is an example timing diagram for an etching method according to an exemplary embodiment. [Figure 6] Each of (a) of FIG. 6, (b) of FIG. 6, and (c) of FIG. 6 is an example timing chart of the flow rate of the carbon-containing gas and the pressure in the chamber. [Figure 7] FIG. 7(a) is a partially enlarged cross-sectional view of an example substrate obtained when the flow rate of the carbon-containing gas is high, and FIG. 7(b) is a partially enlarged cross-sectional view of an example substrate obtained when the flow rate of the carbon-containing gas is low or when no carbon-containing gas is supplied. [Figure 8]FIG. 8(a) is a partially enlarged cross-sectional view of an example substrate obtained when the pressure in the chamber is high, and FIG. 8(b) is a partially enlarged cross-sectional view of an example substrate obtained when the pressure in the chamber is low. [Figure 9] 1 is a graph showing the results of a first experiment. [Figure 10] 13 is a graph showing the results of a second experiment. [Figure 11] FIGS. 11(a), 11(b), and 11(c) are cross-sectional photographs of the twelfth, fifteenth, and sixteenth sample substrates, respectively, after plasma etching. [Figure 12] FIG. 12(a) is a graph showing the results of the fifth experiment, and FIG. 12(b) is a graph showing the results of the sixth experiment. [Figure 13] 13 is a graph showing the results of the seventh experiment. [Figure 14] 13 is a graph showing the results of the eighth to eleventh experiments. [Figure 15] FIG. 13 is a plan view of a sample substrate used in the twelfth and thirteenth experiments. [Figure 16] 13 is a graph showing the results of the 14th to 18th experiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Various exemplary embodiments are described below.

[0009] In one exemplary embodiment, an etching method is provided. The etching method includes the step (a) of providing a substrate in a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film and a mask. The mask is disposed on the silicon-containing film. The etching method further includes the step (b) of etching the silicon-containing film with chemical species from a plasma generated from a processing gas in the chamber. The processing gas includes a hydrogen fluoride gas and a carbon-containing gas. The hydrogen fluoride gas has a highest flow rate among all gases in the processing gas that does not include a rare gas. Alternatively, the hydrogen fluoride gas has a highest flow rate among all gases in the processing gas except for a rare gas.

[0010] In the above embodiment, carbon species generated from the carbon-containing gas are deposited on the mask to protect the mask. Also, the etchant generated from hydrogen fluoride has a small mass but is excellent in etching the silicon-containing film. Therefore, according to the above embodiment, the selectivity of etching the silicon-containing film relative to etching the mask is increased.

[0011] In one exemplary embodiment, the process gas may further include a phosphorus-containing gas, which provides a higher etch rate for the silicon-containing film, resulting in a higher selectivity of the silicon-containing film etch relative to the mask etch.

[0012] In one exemplary embodiment, the process gas may further include an amine-based gas, which provides a higher etch rate for the silicon-containing film, resulting in a higher selectivity of the silicon-containing film etch relative to the mask etch.

[0013] In one exemplary embodiment, the carbon-containing gas may include fluorocarbons and / or hydrofluorocarbons having at least one carbon atom and at most six carbon atoms in their molecules.

[0014] In one exemplary embodiment, in step (b), the flow rate of the carbon-containing gas may be gradually decreased. In one exemplary embodiment, in step (b), the pressure in the chamber may be set to 0.666 Pa or more and 2.666 Pa or less.

[0015] A plasma processing method according to an exemplary embodiment includes the step (a) of providing a substrate in a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film and a mask. The mask is disposed on the silicon-containing film. The etching method further includes the step (b) of etching the silicon-containing film with chemical species from plasma generated from a processing gas in the chamber. The processing gas includes hydrogen fluoride gas and further includes a phosphorus-containing gas or an amine-based gas. The flow rate of hydrogen fluoride gas is the highest among all gases in the processing gas that does not include a rare gas. Alternatively, the flow rate of hydrogen fluoride gas is the highest among all gases in the processing gas except for a rare gas.

[0016] In one exemplary embodiment, the process gas may further include one or more of the following gases: NF3, O2, CO2, CO, N2, He, Ar, Kr, and Xe.

[0017] In one exemplary embodiment, the process gas may further include a halogen-containing gas, such as Cl2, Br2, HCl, HBr, HI, BCl3, CH x Cl y , C.F. x Br y , C.F. x I y , ClF3, IF5, IF7, and BrF3, where x and y are integers of 1 or more.

[0018] In one exemplary embodiment, the process gas may further include an iodine-containing gas. The iodine-containing gas may be HI, IF t , and C x F y I z Here, t, x, y, and z are integers of 1 or greater.

[0019] In one exemplary embodiment, in step (b), the pressure in the chamber may be reduced stepwise.

[0020] In one exemplary embodiment, the silicon-containing film may include a silicon oxide film and / or a silicon nitride film. The silicon-containing film may further include a polycrystalline silicon film. In one exemplary embodiment, the mask may be a carbon-containing mask.

[0021] Various exemplary embodiments will now be described in detail with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals.

[0022] 1 is a flow diagram of an etching method according to one exemplary embodiment. The etching method shown in FIG. 1 (hereinafter referred to as "Method MT") is applied to a substrate having a silicon-containing film. In Method MT, the silicon-containing film is etched.

[0023] Fig. 2 is a partially enlarged cross-sectional view of an example of a substrate to which the etching method shown in Fig. 1 can be applied. The substrate W shown in Fig. 2 can be used in the manufacture of devices such as DRAM and 3D-NAND. The substrate W has a film SF and a mask MK. The substrate W may further have a base region UR. The film SF can be provided on the base region UR. The mask MK is provided on the film SF.

[0024] The film SF is a silicon-containing film. That is, the film SF contains silicon. The film SF may be a single-layer film or a multi-layer film. When the film SF is a single-layer film, it is a silicon film such as a silicon oxide film, a silicon nitride film, or a polycrystalline silicon film, a carbon-containing silicon film such as a SiC film, or a low-dielectric constant film. The low-dielectric constant film is, for example, a film used as an interlayer insulating film, and is formed of SiOC, SiOF, SiCOH, or the like. When the film SF is a multi-layer film, it includes at least one of a silicon oxide film or a silicon nitride film. When the film SF is a multi-layer film, it may further include a polycrystalline silicon film. The film SF may include a plurality of silicon oxide films and a plurality of silicon nitride films stacked alternately. The film SF may include a plurality of silicon oxide films and a plurality of silicon films (for example, polycrystalline silicon films) stacked alternately. The film SF may include a silicon oxide film, a silicon nitride film, and a polycrystalline silicon film.

[0025] The mask MK is formed of a material having an etching rate lower than the etching rate of the film SF in the step STb. The mask MK may be formed of an organic material. That is, the mask MK may be a carbon-containing mask. The mask MK may be formed of, for example, an amorphous carbon film, a photoresist film, a spin-on carbon film (SOC film), or a boron carbide film. Alternatively, the mask MK may be formed of a silicon-containing film such as a silicon-containing anti-reflective film. Alternatively, the mask MK may be a metal-containing mask formed of a metal-containing material such as titanium nitride, titanium oxide, tungsten, or tungsten carbide. The mask MK may have a thickness of 3 μm or more.

[0026] The mask MK is patterned. That is, the mask MK has a pattern to be transferred to the film SF in step STb. When the pattern of the mask MK is transferred to the film SF, a recess such as a hole or a trench is formed in the film SF. The aspect ratio of the recess formed in the film SF in step STb may be 20 or more, 30 or more, 40 or more, or 50 or more. The mask MK may have a line and space pattern.

[0027] In the method MT, a plasma processing apparatus is used for etching the film SF. FIG. 3 is a diagram that shows a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus 1 shown in FIG. 3 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 formed of, for example, aluminum. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. The corrosion-resistant film may be formed of a ceramic such as aluminum oxide or yttrium oxide.

[0028] A passage 12p is formed in a sidewall of the chamber body 12. The substrate W is transferred 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. The gate valve 12g is provided along the sidewall of the chamber body 12.

[0029] A support 13 is provided on the bottom of the chamber body 12. The support 13 is made of an insulating material. The support 13 has a generally cylindrical shape. The support 13 extends upward from the bottom of the chamber body 12 in the internal space 10s. The support 13 supports a substrate support 14. The substrate support 14 is configured to support a substrate W in the internal space 10s.

[0030] The substrate support 14 has a lower electrode 18 and an electrostatic chuck 20. The substrate support 14 may further have an electrode plate 16. The electrode plate 16 is made of a conductor such as aluminum and has a substantially disk-like shape. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is made of a conductor such as aluminum and has a substantially disk-like shape. The lower electrode 18 is electrically connected to the electrode plate 16.

[0031] 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 body and an electrode. The body of the electrostatic chuck 20 has a substantially disk shape and is formed from a dielectric material. The electrode of the electrostatic chuck 20 is a film-like electrode and is provided in the body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the 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 attracted to the electrostatic chuck 20 by the electrostatic attractive force and is held by the electrostatic chuck 20.

[0032] An edge ring 25 is disposed on the substrate support 14. The edge ring 25 is a ring-shaped member. The edge ring 25 may be made of silicon, silicon carbide, quartz, or the like. The substrate W is disposed on the electrostatic chuck 20 and within a region surrounded by the edge ring 25.

[0033] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (e.g., a coolant) is supplied to the flow path 18f from a chiller unit 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 a 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.

[0034] The plasma processing apparatus 1 is provided with a gas supply line 24. The gas supply line 24 supplies a heat transfer gas (for example, He gas) from a heat transfer gas supply mechanism to the gap between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

[0035] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the substrate support 14. The upper electrode 30 is supported on the upper part of the chamber body 12 via a member 32. The member 32 is made of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the chamber body 12.

[0036] The upper electrode 30 may include a top plate 34 and a support 36. The bottom surface of the top plate 34 is the bottom surface on the side of the internal space 10s and defines the internal space 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor that generates little Joule heat. The top plate 34 has a plurality of gas discharge holes 34a penetrating the top plate 34 in its plate thickness direction.

[0037] The support 36 detachably supports the top plate 34. The support 36 is made 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 are connected to the plurality of gas discharge holes 34a, respectively. A gas inlet 36c is formed in the support 36. The gas inlet 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet 36c.

[0038] A gas source group 40 is connected to the gas supply pipe 38 via a flow rate controller group 41 and a valve group 42. The flow rate controller group 41 and the valve group 42 configure a gas supply unit. The gas supply unit may further include a gas source group 40. The gas source group 40 includes a plurality of gas sources. The plurality of gas sources include sources of processing gases used in the method MT. The flow rate controller group 41 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers in the flow rate controller group 41 is a mass flow controller or a pressure-controlled flow rate controller. The valve group 42 includes a plurality of opening and closing valves. Each of the plurality of gas sources in the gas source group 40 is connected to the gas supply pipe 38 via a corresponding flow rate controller in the flow rate controller group 41 and a corresponding opening and closing valve in the valve group 42.

[0039] 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 part 13. The shield 46 prevents reaction by-products from adhering to the chamber body 12. The shield 46 is formed by forming a corrosion-resistant film on the surface of a base material made of, for example, aluminum. The corrosion-resistant film may be made of a ceramic such as yttrium oxide.

[0040] A baffle plate 48 is provided between the support 13 and the side wall of the chamber body 12. The baffle plate 48 is formed, for example, by forming a corrosion-resistant film (a film of yttrium oxide or the like) on the surface of a member made of aluminum. A plurality of through holes are formed in the baffle plate 48. An exhaust 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 exhaust 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.

[0041] The plasma processing apparatus 1 includes a high-frequency power supply 62 and a bias power supply 64. The high-frequency power supply 62 is a power supply that generates high-frequency power HF. The high-frequency power HF has a first frequency suitable for generating plasma. The first frequency is, for example, a frequency within a range of 27 MHz to 100 MHz. The high-frequency power supply 62 is connected to the lower electrode 18 via a matching device 66 and the electrode plate 16. The matching device 66 has a circuit for matching the impedance of the load side (lower electrode 18 side) of the high-frequency power supply 62 to the output impedance of the high-frequency power supply 62. The high-frequency power supply 62 may be connected to the upper electrode 30 via the matching device 66. The high-frequency power supply 62 constitutes an example of a plasma generating unit.

[0042] The bias power supply 64 is a power supply that generates an electric bias. The bias power supply 64 is electrically connected to the lower electrode 18. The electric bias has a second frequency. The second frequency is lower than the first frequency. The second frequency is, for example, a frequency within a range of 400 kHz to 13.56 MHz. When the electric bias is used together with the high frequency power HF, it is applied to the substrate support 14 (in one example, the lower electrode 18) to attract ions to the substrate W. When the electric bias is applied to the lower electrode 18, the potential of the substrate W placed on the substrate support 14 fluctuates within a period defined by the second frequency. Note that the electric bias may be applied to an electrode of the substrate support 14 other than the lower electrode 18, for example, an electrode provided in the electrostatic chuck 20.

[0043] In one embodiment, the electric bias may be a high frequency power LF having a second frequency. When the high frequency power LF is used together with the high frequency power HF, it is used as a high frequency bias power for attracting ions to the substrate W. A bias power supply 64 configured to generate the high frequency power LF is connected to the lower electrode 18 via a matching box 68 and the electrode plate 16. The matching box 68 has a circuit for matching the impedance of the load side (lower electrode 18 side) of the bias power supply 64 to the output impedance of the bias power supply 64.

[0044] It is also possible to generate plasma using high frequency power LF without using high frequency power HF, that is, using only a single high frequency power. In this case, the frequency of the high frequency power LF may be a frequency higher than 13.56 MHz, for example, 40 MHz. In this case, the plasma processing apparatus 1 does not need to include the high frequency power supply 62 and the matching box 66. In this case, the bias power supply 64 constitutes an example of a plasma generating unit.

[0045] In another embodiment, the electric bias may be a pulse wave of voltage. The pulse wave of voltage is periodically generated and applied to the lower electrode 18. The period of the pulse wave of voltage is determined by the second frequency. That is, the time length of the period of the pulse wave of voltage is the reciprocal of the second frequency. The pulse wave of voltage may be a pulse wave of DC voltage. The period of the pulse wave of DC voltage includes two periods. The DC voltage in one of the two periods is, for example, a negative DC voltage, and the potential of the substrate W is set to a negative potential in the one period. The level (i.e., absolute value) of the DC voltage in one of the two periods is higher than the level (i.e., absolute value) of the DC voltage in the other period. The DC voltage in the other period may be either negative or positive. The level of the negative DC voltage in the other period may be greater than zero or may be zero. In this embodiment, the bias power supply 64 is connected to the lower electrode 18 via a low-pass filter and the electrode plate 16. The pulse wave used as the electric bias may include a pulsed voltage having a waveform other than DC. The pulse wave used as the electric bias may include a rectangular pulse, a triangular pulse, an impulse, or a pulse of any other waveform. In addition, when the pulse wave includes a positive voltage and a negative voltage, the bias power supply 64 may be composed of one or more power supplies.

[0046] In one embodiment, the bias power supply 64 may provide a continuous wave of an electric bias to the lower electrode 18. That is, the bias power supply 64 may continuously provide an electric bias to the lower electrode 18. The continuous wave of an electric bias may be provided to the lower electrode 18 during the period in which step STb of the method MT is being performed.

[0047] In another embodiment, the bias power supply 64 may apply a pulse wave of an electric bias to the lower electrode 18. The pulse wave of the electric bias may be applied to the lower electrode 18 periodically. The period of the pulse wave of the electric bias is defined by a third frequency. That is, the time length of the period of the pulse wave of the electric bias is the reciprocal of the third frequency. The third frequency is lower than the second frequency. The third frequency is, for example, 1 Hz or more and 200 kHz or less. In another example, the third frequency may be 5 Hz or more and 100 kHz or less.

[0048] The period of the pulse wave of the electric bias includes two periods, namely, an H period and an L period. The level of the electric bias in the H period (i.e., the level of the pulse of the electric bias) is higher than the level of the electric bias in the L period. That is, the pulse wave of the electric bias may be applied to the lower electrode 18 by increasing or decreasing the level of the electric bias. The level of the electric bias in the L period may be greater than zero. Alternatively, the level of the electric bias in the L period may be zero. That is, the pulse wave of the electric bias may be applied to the lower electrode 18 by alternately switching between supplying and stopping the supply of the electric bias to the lower electrode 18. Here, when the electric bias is a high frequency power LF, the level of the electric bias is the power level of the high frequency power LF. When the electric bias is a high frequency power LF, the level of the high frequency power LF in the pulse of the electric bias may be 2 kW or more. When the electric bias is a pulse wave of a negative polarity DC voltage, the level of the electric bias is the effective value of the absolute value of the negative polarity DC voltage. The duty ratio of the pulse wave of the electric bias, i.e., the proportion of the H period in the period of the pulse wave of the electric bias, is, for example, 1% or more and 80% or less. In another example, the duty ratio of the pulse wave of the electric bias may be 5% or more and 50% or less. Alternatively, the duty ratio of the pulse wave of the electric bias may be 50% or more and 99% or less. The pulse wave of the electric bias may be applied to the lower electrode 18 to perform step STb of the method MT.

[0049] In one embodiment, the high frequency power source 62 may supply a continuous wave of high frequency power HF. That is, the high frequency power source 62 may supply the high frequency power HF continuously. The continuous wave of high frequency power HF may be supplied during the period in which step STb of the method MT is being performed.

[0050] In another embodiment, the high frequency power supply 62 may supply a pulse wave of high frequency power HF. The pulse wave of high frequency power HF may be supplied periodically. The period of the pulse wave of high frequency power HF is defined by a fourth frequency. That is, the time length of the period of the pulse wave of high frequency power HF is the reciprocal of the fourth frequency. The fourth frequency is lower than the second frequency. In one embodiment, the fourth frequency is the same as the third frequency. The period of the pulse wave of high frequency power HF includes two periods, namely, an H period and an L period. The power level of the high frequency power HF in the H period is higher than the power level of the high frequency power HF in the L period of the two periods. The power level of the high frequency power HF in the L period may be greater than zero or may be zero.

[0051] The period of the pulse wave of the high frequency power HF may be synchronized with the period of the pulse wave of the electric bias. The H period in the period of the pulse wave of the high frequency power HF may be synchronized with the H period in the period of the pulse wave of the electric bias. Alternatively, the H period in the period of the pulse wave of the high frequency power HF may not be synchronized with the H period in the period of the pulse wave of the electric bias. The time length of the H period in the period of the pulse wave of the high frequency power HF may be the same as or different from the time length of the H period in the period of the pulse wave of the electric bias.

[0052] When plasma processing is performed in the plasma processing apparatus 1, a gas is supplied from a gas supply unit to the internal space 10s. In addition, a high-frequency electric field is generated between the upper electrode 30 and the lower electrode 18 by supplying high-frequency power HF and / or an electric bias. The generated high-frequency electric field generates plasma from the gas in the internal space 10s.

[0053] The plasma processing apparatus 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 part of the plasma processing apparatus 1. In the control unit 80, an operator can use the input device to input commands and the like to manage the plasma processing apparatus 1. In addition, the control unit 80 can visualize and display the operating status of the plasma processing apparatus 1 using the display device. Furthermore, the storage unit stores a control program and recipe data. The control program is executed by the processor to execute various processes in the plasma processing apparatus 1. The processor executes the control program and controls each part of the plasma processing apparatus 1 according to the recipe data.

[0054] Referring again to Fig. 1, the method MT will be described below taking as an example a case where the method MT is applied to a substrate W shown in Fig. 2 using a plasma processing apparatus 1. When the plasma processing apparatus 1 is used, the method MT can be executed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 by a control unit 80. In the following description, the control of each part of the plasma processing apparatus 1 by the control unit 80 for executing the method MT will also be described.

[0055] In the following description, in addition to Fig. 1, Fig. 4 will be referred to. Fig. 4 is a partially enlarged cross-sectional view of an example of a substrate to which the etching method shown in Fig. 1 is applied.

[0056] 1, the method MT begins with step STa. In step STa, a substrate W is prepared in a chamber 10. The substrate W is placed on an electrostatic chuck 20 in the chamber 10 and held by the electrostatic chuck 20. The substrate W may have a diameter of 300 mm.

[0057] In the method MT, step STb is then performed. In step STb, plasma is generated from the processing gas in the chamber 10. In step STb, the film SF is etched by chemical species from the plasma. As shown in FIG. 4, the film SF can be etched in step STb until the underlying region UR is exposed.

[0058] The process gas used in the step STb contains hydrogen fluoride gas as an etchant gas. The etchant generated from hydrogen fluoride has a small mass but has excellent etching ability for the film SF. Therefore, the selectivity of etching the film SF relative to etching the mask MK is high.

[0059] In the step STb, the process gas may or may not contain a rare gas. The flow rate of hydrogen fluoride gas in the process gas that does not contain a rare gas is the highest among all the flow rates of the gases in the process gas. Alternatively, the flow rate of hydrogen fluoride gas in the process gas is the highest among all the flow rates of the gases in the process gas except for the rare gas.

[0060] Specifically, the flow rate of the hydrogen fluoride gas in step STb may be 70 vol. % or more, 80 vol. % or more, 85 vol. % or more, 90 vol. % or more, or 95 vol. % or more with respect to the total flow rate of the process gas not containing a rare gas or the process gas excluding a rare gas. In addition, when the process gas further contains another gas such as a carbon-containing gas, the flow rate of the hydrogen fluoride gas may be less than 100 vol. %, 99.5 vol. % or less, 98 vol. % or less, or 96 vol. % or less with respect to the total flow rate of the process gas not containing a rare gas or the process gas excluding a rare gas.

[0061] 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 processing gas not including a rare gas or the processing gas excluding a rare gas. By controlling the flow rate of the hydrogen fluoride gas in the processing gas to within such a range, the film SF can be etched at a high etching rate while suppressing the etching of the mask MK. For example, the selectivity ratio of the etching of the film SF to the etching of the mask MK is high, at 5 or more. As a result, even in a process requiring a high aspect ratio such as a manufacturing process of a NAND flash memory having a three-dimensional structure, the film SF can be etched at an effective speed. In addition, due to such a high selectivity ratio, the amount of deposition gas such as a carbon-containing gas added can be suppressed, thereby reducing the risk of the opening of the mask MK being blocked.

[0062] The process gas used in step STb may further include a carbon-containing gas. Carbon species generated from the carbon-containing gas are deposited on the mask MK to protect the mask. Therefore, the selectivity of the etching of the film SF to the etching of the mask MK is further increased.

[0063] The carbon-containing gas is, for example, a hydrocarbon (C x H y ) gas, fluorocarbon gas (C v F w ), and hydrofluorocarbons (C s H t F u) gases. Here, x, y, s, t, u, v, and w are each an integer of 1 or more. The carbon-containing gas may contain fluorocarbon and / or hydrofluorocarbon having one or more and six or less carbon atoms in its molecule. When a carbon-containing gas containing two or more carbon atoms is used, the protective effect of the sidewall surface defining the recess in the mask MK and the film SF can be increased. Furthermore, since hydrogen fluoride is generated from the hydrofluorocarbon gas, the hydrofluorocarbon gas contributes to the improvement of the etching rate of the film SF in addition to the protection of the mask MK by the carbon-containing material.

[0064] As the fluorocarbon gas, for example, one or more of the following gases can be used: CF4, C2F2, C2F4, C3F8, C4F6, C4F8, and C5F8. As the hydrofluorocarbon gas, for example, CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C4H2F6, and C5H2F 10 , c-C5H3F7, and C3H2F4. Examples of the hydrocarbon gas include CH4, C2H6, C3H6, C3H8, and C4H 10 One or more of each of the above gases can be used.

[0065] In one example, a fluorocarbon gas having a carbon number of 2 or more and / or a hydrofluorocarbon gas having a carbon number of 2 or more can be used as the carbon-containing gas. When a fluorocarbon gas having a carbon number of 2 or more and / or a hydrofluorocarbon gas having a carbon number of 2 or more is used, shape abnormalities such as bowing can be effectively suppressed. In addition, by using a fluorocarbon gas having a carbon number of 3 or more and / or a hydrofluorocarbon gas having a carbon number of 3 or more, shape abnormalities can be further suppressed. For example, C4F8 or C4F6 can be used as the fluorocarbon gas having a carbon number of 3 or more. The hydrofluorocarbon gas having a carbon number of 3 or more may contain an unsaturated bond and may contain one or more CF3 groups. For example, C3H2F4, C3H2F6, or C4H2F6 can be used as the hydrofluorocarbon gas having a carbon number of 3 or more.

[0066] The process gas used in step STb may contain a phosphorus-containing gas or an amine-based gas such as NH3 gas. The presence of phosphorus species or amine-based species on the substrate W promotes the supply of etchant to the bottom of the recess. This increases the etching rate of the film SF, which in turn increases the selectivity of the etching of the film SF relative to the etching of the mask MK. The phosphorus species generated from the phosphorus-containing gas also has a protective effect on the sidewalls that define the recesses of the mask MK and the film SF.

[0067] The phosphorus-containing gas includes at least one phosphorus-containing molecule. The phosphorus-containing gas includes tetraphosphorus decaoxide (PO 10The phosphorus-containing gas may include oxides such as phosphorus octoxide (P4O8) and tetraphosphorus hexoxide (P4O6). Tetraphosphorus decaoxide is sometimes called diphosphorus pentoxide (P2O5). The phosphorus-containing gas may include halides such as phosphorus trifluoride (PF3), phosphorus pentafluoride (PF5), phosphorus trichloride (PCl3), phosphorus pentachloride (PCl5), phosphorus tribromide (PBr3), phosphorus pentabromide (PBr5), and phosphorus iodide (PI3). That is, the phosphorus-containing gas may include fluorine or a halogen element other than fluorine as a halogen element. The phosphorus-containing gas may include phosphoryl halides such as phosphoryl fluoride (POF3), phosphoryl chloride (POCl3), and phosphoryl bromide (POBr3). The phosphorus-containing gas may include phosphine (PH3), calcium phosphide (Ca3P2, etc.), phosphoric acid (H3PO4), sodium phosphate (Na3PO4), hexafluorophosphoric acid (HPF6), etc. The phosphorus-containing gas may include fluorophosphines (H x PF y ) may be included. Here, the sum of x and y is 3 or 5. The phosphorus-containing gas may include phosphorus fluoride. An example of phosphorus fluoride may include PF3 or PF5. Examples of fluorophosphines include HPF2 and H2PF3. The process gas may include one or more of the above phosphorus-containing molecules as at least one type of phosphorus-containing molecule. The process gas may include at least one of the following gases as the phosphorus-containing gas: PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3, and PBr5. Each phosphorus-containing molecule included in the process gas may be vaporized by heating or the like and supplied into the chamber 10 when it is liquid or solid.

[0068] The process gas used in the process STb may contain one or more of the following gases: NF3, O2, CO2, CO, N2, He, Ar, Kr, and Xe. Chemical species generated from these gases may suppress clogging of the openings of the mask MK or increase the verticality of the sidewalls of the mask MK.

[0069] The process gas used in the process STb may contain an oxygen-containing gas. The oxygen-containing gas may contain one or more of O2, CO, CO2, H2O, and H2O2 gases.

[0070] The process gas used in the step STb may contain a halogen-containing gas, which suppresses bowing of the sidewall of the film SF.

[0071] The halogen-containing gas in the process gas used in the step STb includes at least one of a carbon-free fluorine-containing gas, a chlorine-containing gas, a bromine-containing gas, and an iodine-containing gas.

[0072] The carbon-free fluorine-containing gas may include, for example, one or more of the following gases: SF6, NF3, XeF2, SiF4, IF7, ClF5, BrF5, AsF5, NF5, PF3, PF5, POF3, BF3, HPF6, and WF6.

[0073] Chlorine-containing gases include Cl2, HCl, and CH x Cl y , ClF3, SiCl2, SiCl4, CCl4, BCl3, PCl3, PCl5, POCl3, etc., where x and y are integers of 1 or more.

[0074] Bromine-containing gases include Br2, HBr, BrF3, CBr2F2, and CF x Br y , PBr3, PBr5, POBr3, etc., where x and y are integers of 1 or more. CF x Br y is, for example, C2F5Br.

[0075] Iodine-containing gases are HI and IF. t , C x F y I z , I2, and PI3, where t, x, y, and z are integers equal to or greater than 1. tFor example, IF5, IF7, etc. CF x I y is, for example, CF3I, C2F5I, C3F7I, etc. The iodine-containing gas is, for example, CF3I gas. In addition to the function of protecting the sidewall of the recess, the iodine-containing gas can contribute to improving the verticality of the sidewall surface of the mask MK. Note that Xe gas having a mass close to that of iodine can also contribute to improving the verticality of the sidewall surface of the mask MK. Therefore, the iodine-containing gas can be used together with or in addition to the Xe gas. Note that the process gas may contain WF6 gas instead of or in addition to the iodine-containing gas.

[0076] In one embodiment, the halogen-containing gas in the process gas used in step STb is Cl2, Br2, HCl, HBr, HI, BCl3, CH x Cl y , C.F. x Br y , C.F. x I y , ClF3, IF5, IF7, and BrF3, where x and y are integers of 1 or more.

[0077] The process gas may further include an inert gas, such as nitrogen gas and one or more of various noble gases, such as Ar gas, Kr gas, and Xe gas.

[0078] To perform the step STb, the control unit 80 controls the gas supply unit to supply the process gas into the chamber 10. The control unit 80 also controls the gas control unit to set the flow rate of the hydrogen fluoride gas contained in the process gas to the above-mentioned flow rate. The control unit 80 also controls the exhaust unit 50 to set the gas pressure in the chamber 10 to a specified pressure. The control unit 80 also controls the plasma generation unit to generate plasma from the process gas. In the plasma processing device 1, the control unit 80 controls the high frequency power supply 62 and the bias power supply 64 to supply high frequency power HF, high frequency power LF, or high frequency power HF and an electric bias.

[0079] In one embodiment, the step STb may be started after the temperature of the substrate support 14 (particularly the electrostatic chuck 20) ​​is set to 0°C or less, -40°C or less, or -50°C or less. In the step STb, the temperature of the substrate support 14 (particularly the electrostatic chuck 20) ​​may be maintained at the temperature before the start of the step STb or may be changed. When the temperature of the substrate W is set to such a temperature, the etching rate of the film SF in the step STb is increased. In order to set the temperature of the substrate support 14, the control unit 80 may control the chiller unit. In addition, when the processing gas contains a phosphorus-containing gas, the temperature of the substrate support 14 may be set to 50°C or less, 30°C or less, or 20°C or less depending on the ratio of the phosphorus-containing gas in the processing gas.

[0080] In step STb, the film SF is etched by halogen species from plasma generated from the processing gas. The halogen species includes fluorine species generated from hydrogen fluoride gas. Hydrogen fluoride is a molecule with a small molecular weight, and the sputtering effect of the chemical species generated from it on the mask MK is small, so etching of the mask MK is suppressed. Therefore, the plasma generated from hydrogen fluoride gas can etch the film SF while suppressing etching of the mask MK. Furthermore, the plasma generated from hydrogen fluoride gas can increase the etching rate of the film SF. Furthermore, the chemical species generated from the carbon-containing gas protects the mask MK. The greater the number of carbon atoms in the molecule contained in the carbon-containing gas, the higher the protective effect of the mask MK. Furthermore, the plasma generated from the phosphorus-containing gas can suppress etching of the mask MK. Furthermore, in a state in which phosphorus species generated from the phosphorus-containing gas are present on the surface of the substrate W, the supply of etchant to the bottom of the recess is promoted, and the etching rate of the film SF is increased. Therefore, according to the method MT, the etching rate is increased in the plasma etching of the film SF, and the selectivity of the etching of the film SF to the etching of the mask MK is increased. Furthermore, when the phosphorus-containing gas contained in the processing gas contains the above-mentioned halogen element and / or when the processing gas contains the above-mentioned halogen-containing gas, the etching rate of the film SF is further increased.

[0081] Also, in step STb, phosphorus species (ions and / or radicals) are supplied to the substrate W from a plasma generated from a phosphorus-containing gas. The phosphorus species may form a protective film containing phosphorus on the surface of the substrate W. The protective film may further contain carbon and / or hydrogen contained in the process gas. In one embodiment, the protective film may further contain oxygen contained in the process gas or contained in the film SF. In one embodiment, the protective film may contain a bond between phosphorus and oxygen.

[0082] Instead of or in addition to forming a protective film, the phosphorus species may form phosphorus bonds with elements contained in the film SF on the sidewall surface that defines the recess in the film SF. If the film SF includes a silicon oxide film, the phosphorus species forms phosphorus-oxygen bonds on the sidewall surface of the film SF. In step STb, the sidewall surface of the film SF is inactivated (or passivated) by the phosphorus species. That is, the sidewall surface of the film SF is passivated.

[0083] Therefore, according to the method MT, the side wall surface of the film SF is suppressed from being etched and the opening of the film SF is prevented from expanding in the lateral direction (side etching).

[0084] In addition, when the mask MK contains carbon, the phosphorus chemical species may form carbon-phosphorus bonds on the surface of the mask MK. The carbon-phosphorus bonds have higher bond energy than the carbon-carbon bonds in the mask MK. Therefore, according to the method MT, the mask MK is protected during plasma etching of the film SF.

[0085] FIG. 5 is referred to below. FIG. 5 is a timing chart of an example of an etching method according to an exemplary embodiment. In FIG. 5, the horizontal axis indicates time. In FIG. 5, the vertical axis indicates the power level of the high frequency power HF, the level of the electric bias, and the supply state of the processing gas. The "L" level of the high frequency power HF indicates that the high frequency power HF is not being supplied or that the power level of the high frequency power HF is lower than the power level indicated by "H". The "L" level of the electric bias indicates that the electric bias is not being applied to the lower electrode 18 or that the level of the electric bias is lower than the level indicated by "H". In addition, the "ON" supply state of the processing gas indicates that the processing gas is being supplied into the chamber 10, and the "OFF" supply state of the processing gas indicates that the supply of the processing gas into the chamber 10 is stopped.

[0086] In one embodiment, in step STb, as shown by a solid line in Fig. 5, a continuous wave of high frequency power HF may be supplied. That is, in the period in which step STb is performed, the high frequency power HF may be supplied continuously. The power level of the high frequency power HF may be set to a level of 2 kW or more and 10 kW or less.

[0087] In step STb of one embodiment, a continuous wave of an electric bias may be applied to the lower electrode 18, as shown by a solid line in Fig. 5. When high frequency power LF is used as the electric bias, the power level of the high frequency power LF may be set to a level of 2 kW or more. The power level of the high frequency power LF may be set to a level of 10 kW or more.

[0088] In step STb of one embodiment, as shown by the dashed line in Fig. 5, the above-mentioned pulse wave of the electric bias may be applied from the bias power supply 64 to the lower electrode 18. When the electric bias is high frequency power LF, the power level of the high frequency power LF may be set to a level of 2 kW or more during the H period in the cycle of the pulse wave of the electric bias. The power level of the high frequency power LF may be set to a level of 10 kW or more during the H period in the cycle of the pulse wave of the electric bias.

[0089] In step STb of an embodiment, the above-mentioned pulse wave of high frequency power HF may be supplied as shown by the dashed line in FIG. 5. In the H period in the cycle of the pulse wave of high frequency power HF, the power level of the high frequency power HF may be set to a level of 1 kW or more and 10 kW or less. As shown in FIG. 5, the cycle of the pulse wave of high frequency power HF may be synchronized with the cycle of the pulse wave of the electric bias. As shown in FIG. 5, the H period in the cycle of the pulse wave of high frequency power HF may be synchronized with the H period in the cycle of the pulse wave of the electric bias. Alternatively, the H period in the cycle of the pulse wave of high frequency power HF may not be synchronized with the H period in the cycle of the pulse wave of the electric bias. The time length of the H period in the cycle of the pulse wave of high frequency power HF may be the same as or different from the time length of the H period in the cycle of the pulse wave of the electric bias.

[0090] In the step STb of one embodiment, as shown in Fig. 5, the supply and stop of the processing gas may be alternately performed. The period during which the processing gas is supplied may be synchronized with the H period in the period of the pulse wave of the high frequency power HF, or may not be synchronized. The period during which the processing gas is supplied may be synchronized with the H period in the period of the pulse wave of the electric bias, or may not be synchronized.

[0091] Hereinafter, reference will be made to (a) of FIG. 6, (b) of FIG. 6, (c) of FIG. 7, (a) of FIG. 7, (b) of FIG. 7, (a) of FIG. 8, and (b) of FIG. 8. (a) of FIG. 6, (b) of FIG. 6, and (c) of FIG. 6 are exemplary timing charts of the flow rate of the carbon-containing gas and the pressure in the chamber. (a) of FIG. 7 is a partially enlarged cross-sectional view of an example substrate obtained when the flow rate of the carbon-containing gas is high, and (b) of FIG. 7 is a partially enlarged cross-sectional view of an example substrate obtained when the flow rate of the carbon-containing gas is low or when no carbon-containing gas is supplied. (a) of FIG. 8 is a partially enlarged cross-sectional view of an example substrate obtained when the pressure in the chamber is high, and (b) of FIG. 8 is a partially enlarged cross-sectional view of an example substrate obtained when the pressure in the chamber is low.

[0092] As shown in (a) of FIG. 6, (b) of FIG. 6, and (c) of FIG. 6, in step STb of an embodiment, the flow rate of the carbon-containing gas contained in the processing gas and / or the pressure in the chamber are changed. For example, the flow rate of the carbon-containing gas contained in the processing gas and / or the pressure in the chamber may be reduced stepwise. As shown in (a) of FIG. 6, in step STb, the flow rate of the carbon-containing gas contained in the processing gas and / or the pressure in the chamber may be reduced in one step. Alternatively, as shown in (b) of FIG. 6, in step STb, the flow rate of the carbon-containing gas contained in the processing gas and / or the pressure in the chamber may be reduced in multiple steps. In the stepwise reduction of the flow rate of the carbon-containing gas contained in the processing gas and / or the pressure in the chamber, the time length of each step may be the same. Alternatively, as shown in (c) of FIG. 6, in the stepwise reduction of the flow rate of the carbon-containing gas contained in the processing gas and / or the pressure in the chamber, the time length of each step may be different.

[0093] When the flow rate of the carbon-containing gas contained in the processing gas is high, the amount of carbon-containing deposits DPC formed on the surface of the substrate W increases. Therefore, the selectivity of etching the film SF relative to etching the mask MK increases, and bowing of the sidewall of the film SF is suppressed as shown in Fig. 7(a). However, when the flow rate of the carbon-containing gas contained in the processing gas is high, the width of the recess formed in the film SF may become small, and the width of the opening of the mask MK and the width at the bottom of the recess formed in the film SF may become small.

[0094] On the other hand, when the flow rate of the carbon-containing gas contained in the processing gas is low or no carbon-containing gas is supplied, the amount of carbon-containing deposits DPC formed on the surface of the substrate W is reduced. Therefore, as shown in FIG. 7B, the width of the opening of the mask MK and the width at the bottom of the recess formed in the film SF are increased. However, bowing of the sidewall of the film SF may occur, and the width of a part of the recess formed in the film SF may be increased.

[0095] Therefore, when the flow rate of the carbon-containing gas contained in the processing gas is gradually reduced in process STb, it is possible to suppress the reduction in the width of the opening in the mask MK and the width at the bottom of the recess in the film SF while maintaining high etching selectivity and the effect of suppressing bowing.

[0096] Furthermore, when the pressure in the chamber in step STb is high, the etching rate of the film SF is high. However, when the pressure in the chamber in step STb is high, the width of the bottom of the recess formed in the film SF may be narrowed, as shown in FIG. 8(a), and bending of the recess may occur.

[0097] On the other hand, when the pressure in the chamber in step STb is low, ions are supplied perpendicularly to the substrate W, so that the verticality of the recesses formed in the film SF is increased, as shown in Fig. 8(b). However, the amount of carbon-containing deposits formed on the side walls of the recesses is reduced, which may cause bowing of the side walls of the film SF.

[0098] Therefore, when the pressure in the chamber is gradually reduced in process STb, it is possible to suppress a decrease in the etching rate of the film SF while suppressing the occurrence of bowing of the sidewall of the film SF, and to improve the verticality of the recess formed in the film SF.

[0099] In one embodiment, in step (b), the flow rate of the carbon-containing gas contained in the process gas may be gradually reduced while the pressure in the chamber is set to 0.666 Pascals (5 mTorr) or more and 2.666 Pascals (20 mTorr) or less. For example, in step (b), the flow rate of the carbon-containing gas contained in the process gas may be gradually reduced while the pressure in the chamber is set to 2 Pascals (15 mTorr).

[0100] Various experiments performed to evaluate method MT are described below.

[0101] (First experiment)

[0102] In the first experiment, eight sample substrates identical to the substrate W shown in FIG. 2, that is, the first to eighth sample substrates, were prepared. The film SF was a multilayer film including a plurality of silicon oxide films and a plurality of silicon nitride films alternately stacked. The mask MK was made of amorphous carbon. In the first experiment, the film SF of the eight sample substrates was plasma-etched using the plasma processing apparatus 1. In the plasma etching, a processing gas including a fluorocarbon gas, a hydrofluorocarbon gas, a fluorine-containing gas not including carbon, and a halogen-containing gas was used. The processing gas used for the plasma etching of the first sample substrate did not include hydrogen fluoride gas. In the processing gas used for the plasma etching of the second to eighth sample substrates, the flow rates of hydrogen fluoride gas relative to the total flow rate of the processing gas were 34.2 vol%, 51.0 vol%, 80.0 vol%, 95.2 vol%, 98.8 vol%, 99.5 vol%, and 100 vol%, respectively. In the first experiment, 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.

[0103] In the first experiment, the selectivity ratio of the etching of the film SF to the etching of the mask MK was obtained from the results of the plasma etching of the film SF of the eight sample substrates. Specifically, the selectivity ratio was obtained by dividing the etching rate of the film SF by the etching rate of the mask MK from the results of the plasma etching of the film SF of the eight sample substrates.

[0104] The results of the first experiment are shown in the graph of Fig. 9. In the graph of Fig. 9, the horizontal axis represents the flow rate ratio. The flow rate ratio is the ratio (volume %) of the flow rate of hydrogen fluoride gas to the total flow rate of the processing gas excluding the rare gas. In the graph of Fig. 9, the vertical axis represents the selectivity ratio. In Fig. 9, reference symbols P1 to P8 respectively represent the selectivity ratios obtained from the results of plasma etching of the film SF of the first to eighth sample substrates.

[0105] As shown in FIG. 9, the results of the first experiment confirmed that the selectivity increases with an increase in the ratio of the flow rate of the hydrogen fluoride gas to the total flow rate of the processing gas excluding the rare gas (hereinafter referred to as the "flow rate ratio"). In particular, it was confirmed that in the region where the flow rate ratio is 80 volume % or more, the rate of increase in the selectivity with respect to the increase in the flow rate ratio is larger (the slope of the approximation curve in the graph of FIG. 9 is steeper) compared to the region where the flow rate ratio is less than 80 volume %. The reason for this is considered to be as follows. In the region where the flow rate ratio is less than 80 volume %, the etching rate of the film SF increases with an increase in the flow rate ratio, thereby increasing the selectivity. However, in this region, the mask is also etched to some extent, so the increase in the selectivity with respect to the increase in the flow rate ratio is relatively gradual. On the other hand, in the region where the flow rate ratio is 80 volume % or more, the etching rate of the film SF tends to saturate, but the etching speed of the mask decreases, thereby increasing the selectivity. That is, in the region where the flow rate ratio is 80 volume % or more, the film SF is etched while maintaining a high etching rate, while the mask is hardly etched at all, so that the rate of increase in the selectivity with respect to the increase in the flow rate ratio becomes large.

[0106] 9 also shows that when the flow rate of hydrogen fluoride gas accounts for 70 volume % or more of the total flow rate of the processing gas excluding the rare gas, a selectivity ratio of 5 or more can be obtained. In particular, when the flow rate of hydrogen fluoride gas accounts for 90 volume % or more of the total flow rate of the processing gas excluding the rare gas, a selectivity ratio of 7 or more can be obtained, and when the flow rate of hydrogen fluoride gas accounts for 95 volume % or more, a selectivity ratio of 7.5 or more can be obtained.

[0107] (Second experiment)

[0108] In the second experiment, three sample substrates, the same as the sample substrate used in the first experiment, that is, sample substrates No. 9 to No. 11, were prepared. In the second experiment, the plasma etching of the film SF of the three sample substrates was performed using the plasma processing apparatus 1. In the plasma etching, a processing gas containing hydrogen fluoride gas and a carbon-containing gas was used. For the ninth sample substrate, a processing gas containing hydrogen fluoride gas and CH2F2 gas was used. For the tenth sample substrate, a processing gas containing hydrogen fluoride gas and C4F8 gas was used. For the eleventh sample substrate, a processing gas containing hydrogen fluoride gas and C4F6H2 gas was used. In the second experiment, 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.

[0109] In the second experiment, the selectivity ratio of the etching of the film SF to the etching of the mask MK was obtained from the results of the plasma etching of the film SF of the three sample substrates. Specifically, the selectivity ratio was obtained by dividing the etching rate of the film SF by the etching rate of the mask MK from the results of the plasma etching of the film SF of the three sample substrates.

[0110] The results of the second experiment are shown in the graph of Fig. 10. In the graph of Fig. 10, reference characters Sub.9 to 11 indicate the selectivity ratios obtained from the results of plasma etching of the film SF of the ninth to eleventh sample substrates.

[0111] 10, the results of the second experiment confirmed that the selectivity ratio was 6 or more for all sample substrates. In particular, it was confirmed that the selectivity ratio of the 11th sample substrate was about 14, which was the highest selectivity ratio.

[0112] (Third experiment)

[0113] In the third experiment, four sample substrates, the same as the sample substrate used in the first experiment, i.e., sample substrates No. 12 to No. 15, were prepared. In the third experiment, the plasma etching of the film SF of the four sample substrates was performed using the plasma processing apparatus 1. In the plasma etching, a processing gas containing hydrogen fluoride gas and C4F8 gas was used. The processing gas used for the twelfth sample substrate did not contain any other gas. The processing gas used for the thirteenth sample substrate contained 10 sccm of Cl2 gas. The processing gas used for the fourteenth sample substrate contained 10 sccm of HBr gas. The processing gas used for the fifteenth sample substrate contained 10 sccm of CF3I gas. In the plasma etching of the four sample substrates, the pressure in the chamber was 23 mTorr (3.066 Pa). In addition, the high frequency power HF was 40 MHz and 5.5 kW. As an electric bias, a pulse wave of -6 kV voltage was periodically supplied at a frequency of 400 kHz. The plasma etching time for the four sample substrates was 6 minutes. In the third experiment, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to -70°C before the start of plasma etching.

[0114] In the third experiment, the width of the recess formed in the film SF was measured at the location where bowing occurred on the sidewall of the film SF. As a result, the width of the recess in the thirteenth sample substrate was 14 nm smaller than that of the twelfth sample substrate. The width of the recess in the fourteenth sample substrate was 19 nm smaller than that of the twelfth sample substrate. In addition, the width of the recess in the fifteenth sample substrate was 42 nm smaller than that of the twelfth sample substrate. As a result of the third experiment, it was confirmed that bowing of the sidewall of the film SF was suppressed when the processing gas contained a halogen-containing gas such as Cl2 gas, HBr gas, or CF3I gas. In addition, it was confirmed that bowing of the sidewall of the film SF was significantly suppressed when the halogen-containing gas contained iodine having a relatively high mass.

[0115] (Fourth experiment)

[0116] In the fourth experiment, a 16th sample substrate was prepared, which was the same as the sample substrate used in the first experiment. In the fourth experiment, the plasma etching of the film SF of the 16th sample substrate was performed using the plasma processing apparatus 1. In the plasma etching, a processing gas containing hydrogen fluoride gas, C4F8 gas, and Xe gas was used. In the plasma etching of the 16th sample substrate, the pressure in the chamber was 23 mTorr (3.066 Pa). Moreover, the high frequency power HF was 40 MHz, 5.5 kW high frequency power. Moreover, as an electric bias, a pulse wave of a voltage of -6 kV was periodically supplied at a frequency of 400 kHz. The time for plasma etching of the 16th sample substrate was 6 minutes. In addition, in the fourth experiment, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to a temperature of -70°C before the start of the plasma etching.

[0117] 11(a), 11(b), and 11(c) are cross-sectional photographs of the twelfth, fifteenth, and sixteenth sample substrates after plasma etching, respectively. As shown in FIG. 11(a), the side of the mask MK of the twelfth sample substrate was tapered. On the other hand, as shown in FIG. 11(b), the side of the mask MK of the fifteenth sample substrate etched using a processing gas containing CF3I gas had a high verticality. Also, as shown in FIG. 11(c), the side of the mask MK of the sixteenth sample substrate etched using a processing gas containing Xe gas had a high verticality. Since Xe (xenon) has a mass close to that of iodine, the cross-sectional profile of the fifteenth sample substrate and the cross-sectional profile of the sixteenth sample substrate were similar to each other, as shown in FIG. 11(b) and FIG. 11(c). This shows that bowing of the sidewall of the film SF can be suppressed by using a gas containing an element having a relatively large mass, such as iodine and / or Xe.

[0118] (5th and 6th Experiments)

[0119] In the fifth experiment, the plasma processing apparatus 1 was used to generate plasma from a processing gas that was a mixed gas of hydrogen fluoride gas and argon gas, and to etch a silicon oxide film. In the sixth experiment, the plasma processing apparatus 1 was used to generate plasma from a processing gas that was a mixed gas of hydrogen fluoride gas, argon gas, and PF3 gas, and to etch a silicon oxide film. In the fifth and sixth experiments, the silicon oxide film was etched while changing the temperature of the electrostatic chuck 20. In the fifth and sixth experiments, a quadrupole mass spectrometer was used to measure the amount of hydrogen fluoride (HF) and the amount of SiF3 in the gas phase during etching of the silicon oxide film. The results of the fifth and sixth experiments are shown in (a) and (b) of FIG. 12. (a) of FIG. 12 shows the relationship between the temperature of the electrostatic chuck 20 and the amount of hydrogen fluoride (HF) and the amount of SiF3 during etching of the silicon oxide film in the fifth experiment. FIG. 12(b) shows the relationship between the temperature of the electrostatic chuck 20 and the amount of hydrogen fluoride (HF) and the amount of SiF3 when etching a silicon oxide film in the sixth experiment.

[0120] As shown in FIG. 12(a), in the fifth experiment, when the temperature of the electrostatic chuck 20 was about −60° C. or lower, the amount of hydrogen fluoride (HF) as an etchant decreased, and the amount of SiF3 as a reaction product generated by etching the silicon oxide film increased. That is, in the fifth experiment, when the temperature of the electrostatic chuck 20 was about −60° C. or lower, the amount of the etchant consumed in etching the silicon oxide film increased. On the other hand, as shown in FIG. 12(b), in the sixth experiment, when the temperature of the electrostatic chuck 20 was 20° C. or lower, the amount of hydrogen fluoride (HF) decreased, and the amount of SiF3 increased. That is, in the sixth experiment, when the temperature of the electrostatic chuck 20 was 20° C. or lower, the amount of the etchant consumed in etching the silicon oxide film increased. The process gas used in the sixth experiment was different from the process gas used in the fifth experiment in that it contained PF3 gas. Therefore, in the sixth experiment, a state in which phosphorus species exist on the surface of the silicon oxide film during etching of the silicon oxide film was formed. From this, it was confirmed that when phosphorus species exist on the surface of the substrate, the supply of etchant to the bottom of the recess is promoted, and the etching rate of the silicon-containing film is increased.

[0121] (7th experiment)

[0122] In the seventh experiment, a plurality of sample substrates were prepared, which were the same as the sample substrates prepared in the first experiment. In the seventh experiment, plasma was generated from a processing gas using a plasma processing apparatus 1 to etch the film SF of a plurality of sample substrates. The processing gas used in the seventh experiment contained hydrogen fluoride gas and fluorocarbon gas. In the seventh experiment, the flow rate ratio of PF3 gas in each of the processing gases used for the plurality of sample substrates was different from each other. Here, the flow rate ratio of PF3 gas is the flow rate ratio of PF3 gas to the flow rate of the processing gas. In the plasma etching of the seventh experiment, the pressure in the chamber was 27 mTorr (3.6 Pa). Moreover, the high frequency power HF was a high frequency power of 40 MHz and 4.4 kW. Moreover, a high frequency bias power of 400 kHz and 6 kW was supplied as an electric bias. The plasma etching time of the seventh experiment was 6 minutes. In the seventh experiment, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to a temperature of -40°C before the start of plasma etching.

[0123] In the seventh experiment, the etching rate of the film SF was obtained from the etching results of each of the films SF of a plurality of sample substrates. Then, the relationship between the ratio of the flow rate of the PF3 gas and the etching rate of the film SF was obtained. The results are shown in FIG. 13. As shown in FIG. 13, it was confirmed that a high etching rate can be obtained if the ratio of the flow rate of the PF3 gas to the flow rate of the processing gas is 2% or more (or 2.5% or more). In other words, it was confirmed that a high etching rate can be obtained if the flow rate of the phosphorus-containing gas is 2% or more (or 2.5% or more) to the flow rate of the processing gas containing hydrogen fluoride gas, C4F8 gas, and phosphorus-containing gas (PF3 gas).

[0124] (Experiments 8 to 11)

[0125] In each of the eighth and ninth experiments, a plurality of substrates each having a silicon oxide film were prepared. In each of the eighth and ninth experiments, plasma was generated from a processing gas using the plasma processing apparatus 1 to etch the silicon oxide films of the plurality of sample substrates. In each of the eighth and ninth experiments, the temperatures of the substrate support 14 when the silicon oxide films of the plurality of sample substrates were etched were different from each other. In each of the tenth and eleventh experiments, a plurality of substrates each having a silicon nitride film were prepared. In each of the tenth and eleventh experiments, plasma was generated from a processing gas using the plasma processing apparatus 1 to etch the silicon nitride films of the plurality of sample substrates. In each of the tenth and eleventh experiments, the temperatures of the substrate support 14 when the silicon nitride films of the plurality of sample substrates were etched were different from each other. The processing gas used in each of the eighth to eleventh experiments contained hydrogen fluoride gas and C4F8 gas. The ratio of the flow rate of PF3 gas to the flow rate of the processing gas used in the eighth and tenth experiments was 2.5%. The treatment gas used in the ninth experiment and the eleventh experiment did not contain PF3 gas. The other conditions in each of the eighth to eleventh experiments were the same as the corresponding conditions described above for the seventh experiment.

[0126] In the eighth and ninth experiments, the etching rate of the silicon oxide film was obtained from the results of etching the silicon oxide film of each of the sample substrates. In the tenth and eleventh experiments, the etching rate of the silicon nitride film was obtained from the results of etching the silicon nitride film of each of the sample substrates. FIG. 14 shows the relationship between the temperature of the substrate support 14 set in the eighth to eleventh experiments and the obtained etching rate. In FIG. 14, legends No. 8, No. 9, No. 10, and No. 11 respectively indicate the results of the eighth to eleventh experiments. As shown in FIG. 14, it was confirmed that the etching rate of the silicon oxide film in the eighth experiment, in which the process gas contained PF3 gas, was higher than the etching rate of the silicon oxide film in the ninth experiment, in which the process gas not containing PF3 gas was used. In addition, it was confirmed from the results of the eighth experiment that the etching rate of the silicon oxide film was higher when the temperature of the substrate support 14 was set to 0° C. or lower when the process gas containing PF3 gas was used.

[0127] (Experiments 12 and 13)

[0128] In each of the twelfth and thirteenth experiments, the plasma processing apparatus 1 was used to generate plasma from a processing gas to etch the film SF of the sample substrate. FIG. 15 is a plan view of the sample substrate used in the twelfth and thirteenth experiments. In the sample substrate, the film SF had a laminated structure including a silicon oxide film, a polycrystalline silicon film, and a silicon nitride film. The mask MK was made of amorphous carbon. As shown in FIG. 15, the mask MK defined a plurality of openings OP. Each of the plurality of openings OP had a rectangular planar shape as shown in FIG. 15. The plurality of openings OP were two-dimensionally arranged to provide a plurality of rows and a plurality of columns thereof as shown in FIG. 15.

[0129] In the twelfth experiment, the process gas was a mixed gas containing H2 gas, Cl2 gas, HBr gas, fluorocarbon gas, hydrofluorocarbon gas, and NF3 gas. In the plasma etching in the twelfth experiment, the pressure in the chamber was 15 mTorr (2 Pa). The high frequency power HF was 40 MHz, 5.5 kW. The electric bias was 400 kHz, 7 kW high frequency bias power. The plasma etching time in the twelfth experiment was 1350 seconds. In the twelfth experiment, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to −35° C. before the start of the plasma etching.

[0130] In the thirteenth experiment, the processing gas was a mixture of hydrogen fluoride gas, PF3 gas, NF3 gas, Cl2 gas, HBr gas, C4F8 gas, and CH2F2 gas. In the plasma etching in the thirteenth experiment, the pressure in the chamber was 25 mTorr (3.066 Pa). The high frequency power HF was 40 MHz and 5.5 kW. As the electric bias, a pulse wave of a voltage of -6 kV was periodically supplied at a frequency of 400 kHz. The plasma etching time in the thirteenth experiment was 420 seconds. In the thirteenth experiment, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to -70°C before the start of plasma etching.

[0131] In the twelfth and thirteenth experiments, the etching rate of the film SF and the selectivity of the film SF to the etching of the mask MK were obtained. As a result, the etching rate of the film SF in the thirteenth experiment was about three times that of the film SF in the twelfth experiment. Also, the selectivity in the thirteenth experiment was about 2.5 times that of the film SF in the twelfth experiment. Therefore, it was confirmed that the processing gas used in step STb of the method MT increases the etching rate of the film SF and the selectivity of the film SF to the etching of the mask MK.

[0132] In addition, in each of the 12th and 13th experiments, the LER (Line Edge Roughness) of the line LN of the mask MK shown in Fig. 15 was obtained. As a result, the LER in the 12th experiment was 26.5 nm, and the LER in the 13th experiment was 16.8 nm. Therefore, it was confirmed that the processing gas used in the step STb of the method MT can suppress the deterioration of the shape of the mask MK.

[0133] (Experiments 14 to 18)

[0134] In each of the fourteenth to eighteenth experiments, plasma was generated from a processing gas using the plasma processing apparatus 1, and the film SF of the sample substrate was etched. The sample substrate used in each of the fourteenth to eighteenth experiments was the same as the sample substrate prepared in the first experiment. In the plasma etching, a processing gas containing hydrogen fluoride gas was used. In the fourteenth experiment and the sixteenth to eighteenth experiments, the processing gas further contained C4F8 gas as a carbon-containing gas. In the fifteenth experiment, the processing gas did not contain a carbon-containing gas. In the sixteenth experiment, the flow rate of the carbon-containing gas was reduced to 0 sccm in two stages between the start and end of the plasma etching. In the seventeenth experiment, the flow rate of the carbon-containing gas was reduced to 0 sccm in three stages between the start and end of the plasma etching. In the eighteenth experiment, the flow rate of the carbon-containing gas was reduced to 0 sccm in five stages between the start and end of the plasma etching. In the plasma etching of the 14th to 18th experiments, the pressure in the chamber was 23 mTorr (3.066 Pa). The high frequency power HF was 40 MHz and 5.5 kW. As the electric bias, a pulse wave of -6 kV voltage was periodically supplied at a frequency of 400 kHz. In the 14th to 18th experiments, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to -70°C before the start of plasma etching.

[0135] In each of the 14th to 18th experiments, the width of the bottom of the recess formed in the film SF (Bottom CD) and the width of the recess at the location where bowing occurs on the side wall of the film SF (Bow CD) were obtained. In addition, the difference between the Bottom CD and the Bow CD (Difference) was obtained. FIG. 16 shows the results of the 14th to 18th experiments. In FIG. 16, No. 14, No. 15, No. 16, No. 17, and No. 18 show the results of the 14th to 18th experiments, respectively. In FIG. 16, the values ​​of the Bottom CD obtained in each experiment are normalized by the Bottom CD obtained in the 14th experiment. In FIG. 16, the values ​​of the Bow CD obtained in each experiment are normalized by the Bow CD obtained in the 14th experiment. In FIG. 16, the values ​​of the Difference obtained in each experiment are normalized by the Difference obtained in the 14th experiment.

[0136] In the fifteenth experiment, since the processing gas did not contain a carbon-containing gas, the bottom CD was larger than that in the fourteenth experiment, but the bow CD was also larger than that in the fourteenth experiment. On the other hand, in each of the sixteenth to eighteenth experiments, the increase in the bow CD was suppressed compared to that in the fourteenth experiment, and the bottom CD was increased compared to that in the fourteenth experiment. Also, in each of the sixteenth to eighteenth experiments, the difference was considerably smaller than that in the fourteenth experiment. Therefore, it was confirmed that it is possible to increase the verticality of the recess while suppressing the bow CD by gradually decreasing the flow rate of the carbon-containing gas in the processing gas during plasma etching.

[0137] (19th experiment)

[0138] In the 19th experiment, plasma etching was performed on the film SF of the same sample substrate as the sample substrate in the 17th experiment. The plasma etching conditions in the 19th experiment were different from those in the 17th experiment in that the pressure in the chamber was 15 mTorr (2 Pa). In the 19th experiment, the increase in the Bow CD was suppressed compared to the Bow CD in the 14th experiment, and the Bottom CD was increased by about 1.4 times compared to the Bottom CD in the 14th experiment. Therefore, it was confirmed that it is possible to further increase the verticality of the recess while suppressing the Bow CD by setting the pressure in the chamber at a relatively low pressure and gradually decreasing the flow rate of the carbon-containing gas contained in the processing gas.

[0139] (Experiments 20 and 21)

[0140] In the twentieth and twenty-first experiments, the plasma processing apparatus 1 was used to perform plasma etching of the film SF of the same sample substrate as the sample substrate of the first experiment. In the twentieth experiment, a mixed gas containing H2 gas, hydrofluorocarbon gas, fluorocarbon gas, fluorine-containing gas, and halogen-containing gas was used as the processing gas for plasma etching. In the twenty-first experiment, a mixed gas containing hydrogen fluoride gas, C4F8 gas, and O2 gas was used as the processing gas for plasma etching. In the plasma etching of the twentieth and twenty-first experiments, the pressure in the chamber was 27 mTorr (3.6 Pa). Moreover, the high frequency power HF was 40 MHz, 4.4 kW high frequency power. Moreover, as the electric bias, a high frequency bias power of 400 kHz, -6 kV was used. In the twentieth and twenty-first experiments, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to -40°C before the start of plasma etching.

[0141] In the 20th and 21st experiments, the etching rate of the film SF and the selectivity of the etching of the film SF to the etching of the mask MK were obtained. As a result, the etching rates of the film SF in the 20th and 21st experiments were 310 nm / min and 296 nm / min, respectively. Also, the selectivity of the film SF in the 20th and 21st experiments was 3.24 and 6.52, respectively. As a result of the 20th to 21st experiments, it was confirmed that the etching rate of the mask MK was reduced and the selectivity was improved by adding hydrogen fluoride gas to the processing gas.

[0142] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0143] For example, the plasma processing apparatus used in the method MT may be a capacitively coupled plasma processing apparatus other than the plasma processing apparatus 1. Alternatively, the plasma processing apparatus used in the method MT may be an inductively coupled plasma processing apparatus, an ECR (electron cyclotron resonance) plasma processing apparatus, or a plasma processing apparatus that generates plasma using surface waves such as microwaves.

[0144] In addition to the bias power supply 64 that supplies high frequency power LF to the lower electrode 18, the plasma processing apparatus may also include another bias power supply configured to apply pulses of voltage intermittently or periodically to the lower electrode 18.

[0145] Furthermore, the disclosed embodiments further include the following aspects. (A1) A process gas for plasma etching of a silicon oxide film, the process gas including a hydrogen fluoride gas, a phosphorus-containing gas, and a carbon-containing gas. (A2) The process gas according to A1, wherein the flow rate of the hydrogen fluoride gas is the largest among the flow rate of the hydrogen fluoride gas, the flow rate of the phosphorus-containing gas, and the flow rate of the carbon-containing gas. (B1). (a) providing a substrate in a chamber of a plasma processing apparatus, the substrate including a silicon-containing film; (b) etching the silicon-containing film with chemical species from a plasma formed in the chamber from a process gas, the process gas including a phosphorus-containing gas, a fluorine-containing gas, a hydrofluorocarbon gas, and a halogen-containing gas containing a halogen element other than fluorine; An etching method comprising: (B2) The etching method according to (B1), wherein the fluorine-containing gas includes at least one gas selected from the group consisting of a fluorocarbon gas and a carbon-free fluorine-containing gas. (B3) The etching method according to (B2), wherein the carbon-free fluorine-containing gas is nitrogen trifluoride gas or sulfur hexafluoride gas. (B4) The etching method according to any one of B1 to B3, wherein the halogen-containing gas is Cl2 gas and / or HBr gas.

[0146] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0147] Reference Signs List 1: plasma processing apparatus, 10: chamber, 14: substrate support, 80: control unit, W: substrate, SF: film.

Claims

1. (a) providing a substrate in a chamber of a plasma processing apparatus, the substrate including a silicon-containing film; (b) etching the silicon-containing film with species from a plasma generated from a process gas in the chamber; Including, the process gas includes hydrogen fluoride gas and a phosphorus-containing gas; the flow rate of the hydrogen fluoride gas is the highest among all the flow rates of gases in the processing gas that does not include a rare gas, or the flow rate of the hydrogen fluoride gas is the highest among all the flow rates of gases in the processing gas that does not include a rare gas; Etching method.

2. 2. The etching method of claim 1, wherein the phosphorus-containing gas includes one or more of the following gases: oxide of phosphorus, halide of phosphorus, phosyl halide, phosphine, calcium phosphide, phosphoric acid, sodium phosphate, and fluorophosphine hexafluorophosphate.

3. The phosphorus-containing gas is P ４ O １０ , P ４ O ８ , P ４ O ６ , P.F. ３ , P.F. ５ , PCl ３ , PCl ５ , PBr ３ , PBr ５ , P.I. ３ , POF ３ , POCl ３ , POBr ３ , P.H. ３ , Ca ３ P ２ , H ３ P.O. ４ , Na ３ P.O. ４ , H.P.F. ２ , H ２ P.F. ３ , H.P.F. ６ 2. The method of claim 1, further comprising one or more of the following gases:

4. 4. The etching method according to claim 1, wherein the process gas further contains a halogen-containing gas.

5. The halogen-containing gas is Cl ２ , B ２ , HCl, HBr, HI, BCl ３ , C.H. ｘ C ｙ , C.F. ｘ B ｙ , C.F. ｘ I ｙ , ClF ３ , I.F. ５ , I.F. ７ , BrF ３ 5. The etching method according to claim 4, wherein the etching gas includes one or more of the gases selected from the group consisting of x and y, each of which is an integer of 1 or more.

6. The etching method of claim 4 , wherein the halogen-containing gas includes carbon.

7. The halogen-containing gas is CH ｘ C ｙ , C.F. ｘ B ｙ , C.F. ｘ I ｙ , C ｘ F ｙ I ｚ 7. The etching method according to claim 6, wherein x, y, and z are integers of 1 or more.

8. The halogen-containing gas is CH ｘ C ｙ , C.F. ｘ B ｙ 6. The etching method according to claim 5, wherein the etching gas includes one or more of the gases listed above, where x and y are integers of 1 or more.

9. The halogen-containing gas is CCl ４ , CBr ２ F ２ , C ２ F ５ Br, C.F. ３ I.C. ２ F ５ I.C. ３ F ７ 7. The etching method according to claim 6, further comprising any one or more gases selected from the group consisting of I and II.

10. The etching method according to any one of claims 1 to 9, wherein the process gas further comprises a carbon-containing gas.

11. 11. The etching method according to claim 10, wherein the carbon-containing gas includes a fluorocarbon and / or a hydrofluorocarbon having one or more and six or less carbon atoms in the molecule.

12. The process gas is NF ３ , O ２ , CO ２ , C.O., N ２ 12. The etching method according to claim 1, further comprising one or more of the following gases: He, Ar, Kr, and Xe.

13. 13. The etching method according to claim 1, wherein in (b), the pressure inside the chamber is set to 0.666 Pa or more and 2.666 Pa or less.

14. The etching method according to any one of claims 1 to 13, wherein the silicon-containing film includes a silicon oxide film and / or a silicon nitride film.

15. 15. The etching method of claim 14, wherein the silicon-containing film further comprises a polycrystalline silicon film.

16. the substrate has a mask on the silicon-containing film; The mask is a carbon-containing mask or a metal-containing mask. The etching method according to any one of claims 1 to 15.

17. (a) providing a substrate in a chamber of a plasma processing apparatus, the substrate including a silicon-containing film; (b) etching the silicon-containing film with species from a plasma generated from a process gas in the chamber; Including, The process gas includes hydrogen fluoride gas and a phosphorus-containing gas. Etching method.

18. the substrate is placed on a substrate support within the chamber; In the above (b), A high frequency power having a first frequency is supplied to the substrate support or an upper electrode provided above the substrate support; providing an electrical bias having a second frequency to the substrate support; The etching method according to any one of claims 1 to 17.

19. 20. The etching method according to claim 18, wherein the electrical bias is a high frequency power having the second frequency or a pulse wave of a voltage periodically generated at the second frequency.

20. 20. The etching method of claim 19, wherein the pulsed electrical bias is periodically applied to the substrate support at a third frequency.

21. 21. The etching method according to claim 18, wherein the step (b) is started after the temperature of the substrate support is set to 0° C. or lower.

22. A chamber; a substrate support disposed within the chamber; a gas supply configured to supply a gas into the chamber; a plasma generating unit configured to generate a plasma from a gas in the chamber; A control unit configured to control the gas supply unit and the plasma generation unit; Equipped with the control unit is configured to execute a step of etching the silicon-containing film with chemical species from plasma generated from a process gas in the chamber, with the substrate including the silicon-containing film being placed on the substrate support; The process gas includes hydrogen fluoride gas and a phosphorus-containing gas. Plasma processing equipment.

Images