Etching method and plasma processing apparatus

Abstract

The etching method of the present invention includes a process (a) of preparing a substrate in a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film and a mask. The mask contains carbon. The etching method also includes a process (b) of etching the silicon-containing film by chemical species from a plasma generated in the chamber from a processing gas. The processing gas includes a halogen element and phosphorus. In the process (b), a bond of carbon and phosphorus is formed on a surface of the mask.

Description

Technical Field

[0001] Exemplary embodiments of the present invention relate to an etching method and a plasma treatment apparatus. Background Technology

[0002] In the manufacture of electronic devices, a silicon-containing film on a substrate is plasma etched. During plasma etching of the silicon-containing film, a process gas containing fluorocarbons is used. This type of plasma etching is described in U.S. Patent Application Publication No. 2016 / 0343580. Summary of the Invention

[0003] This invention provides a technique for protecting a substrate during plasma etching of a silicon-containing film.

[0004] In one exemplary embodiment, an etching method is provided. The etching method includes a step (a) in which a substrate is prepared in a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film and a mask. The mask contains carbon. The etching method further includes a step (b) in which the silicon-containing film is etched by chemical species from a plasma generated in the chamber by a process gas. The process gas contains a halogen element and phosphorus. In step (b), carbon-phosphorus bonds are formed on the surface of the mask.

[0005] According to an exemplary embodiment, it becomes possible to protect the substrate during plasma etching of a silicon-containing film. Attached Figure Description

[0006] Figure 1 This is a flowchart of an exemplary embodiment of an etching method.

[0007] Figure 2 It is applicable Figure 1 A partially enlarged cross-sectional view of a substrate for an example of the etching method shown.

[0008] Figure 3 This is a diagram schematically illustrating a plasma processing apparatus according to an exemplary embodiment.

[0009] Figure 4 (a) is applicable Figure 1 A partially enlarged cross-sectional view of a substrate illustrating an example of the etching method. Figure 4 (b) is a partially enlarged cross-sectional view of an example substrate etched by plasma generated from a phosphorus-free processing gas.

[0010] Figure 5 This is an example timing diagram of an etching method according to an exemplary embodiment.

[0011] Figure 6(a) is a graph showing the XPS analysis results of the protective film PF formed in an experimental example of etching a silicon oxide film in the STP process. Figure 6 (b) is a graph showing the results of XPS analysis of the protective film PF formed in an experimental example where the silicon nitride film was etched in the STP process.

[0012] Figure 7 This is another timing diagram of an etching method according to an exemplary embodiment.

[0013] Figure 8 This is a top view of another example of a substrate.

[0014] Figure 9 (a) is along Figure 8 A sectional view cut along line IXA-IXA. Figure 9 (b) is along Figure 8 A sectional view cut along line IXB-IXB.

[0015] Figure 10 This is a graph showing the relationship between the flow rate of PF3 gas in the treatment gas and the etching rate of the silicon oxide film, as determined in Experiment 1.

[0016] Figure 11 This is a graph showing the relationship between the flow rate of PF3 gas in the treatment gas determined in Experiment 1 and the maximum width of the opening formed on the silicon oxide film.

[0017] Figure 12 This is a graph showing the relationship between the flow rate of PF3 gas and the selectivity in the treated gas, as determined in Experiment 1.

[0018] Figure 13 This is a graph showing the relationship between the flow rate of PF3 gas in the treated gas and LER and LWR, as determined in Experiment 2.

[0019] Figure 14 This is a flowchart of an etching method (method MT2) according to another exemplary embodiment.

[0020] Figure 15 (a) is a partial enlarged cross-sectional view of an example substrate in the state of process ST22 of method MT2. Figure 15 (b) is a partial enlarged cross-sectional view of an example substrate in the state of process ST23 of method MT2. Figure 15 (c) is a partial enlarged cross-sectional view of an example substrate after the application of method MT2.

[0021] Figure 16 This is a flowchart of an etching method (method MT3) of yet another exemplary embodiment.

[0022] Figure 17 (a) is a partial enlarged cross-sectional view of a substrate in the state of process STP3 of the applicable method MT3. Figure 17 (b) is a partial enlarged cross-sectional view of an example substrate after the application of method MT3. Detailed Implementation

[0023] The following describes various exemplary embodiments.

[0024] In one exemplary embodiment, an etching method is provided. The etching method includes a step (a) in which a substrate is prepared in a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film and a mask. The mask contains carbon. The etching method further includes a step (b) in which the silicon-containing film is etched by chemical species from a plasma generated in the chamber by a process gas. The process gas contains a halogen element and phosphorus. In step (b), carbon-phosphorus bonds are formed on the surface of the mask. The halogen element may be fluorine.

[0025] In the etching method of the above embodiments, the bonding energy between carbon and phosphorus formed on the surface of the mask is higher than that between carbons in the mask. Therefore, according to the etching method of the above embodiments, the mask is protected when plasma etching the silicon-containing film. Therefore, according to the above embodiments, it becomes possible to protect the substrate when plasma etching the silicon-containing film. Furthermore, according to the etching method of the above embodiments, the deterioration of the mask shape during plasma etching of the silicon-containing film is suppressed.

[0026] In one exemplary embodiment, the silicon-containing film may include a silicon oxide film. The silicon-containing film may also include at least one of a silicon nitride film, a polycrystalline silicon film, a silicon carbon film, and a low dielectric constant film.

[0027] In one exemplary embodiment, the mask may include a portion of the silicon-containing film in which the mask occupies a high proportion relative to the openings defined by the mask and a portion in which the proportion is low. The portion of the mask in which the proportion is high relative to the openings is a portion in which the mask is densely formed (hereinafter referred to as "dense region"). The portion of the mask in which the proportion is low relative to the openings is a portion in which the mask is roughly formed (hereinafter referred to as "rough region"). Typically, for the mask in the rough region, more etching is performed by plasma etching of the silicon-containing film than for the mask in the dense region. However, in this embodiment, the mask is protected by carbon and phosphorus bonds formed on its surface. Therefore, the amount of etching of the mask in the rough region is reduced. As a result, the difference in the amount of etching of the mask in the rough region and the amount of etching of the mask in the dense region is reduced. Furthermore, the shape degradation of the mask having both the rough region and the dense region is suppressed.

[0028] In one exemplary embodiment, the etching method may further include step (c) of forming a protective film on the sidewall surface that divides the opening formed by etching in step (b). The protective film contains phosphorus contained in the process gas. Steps (b) and (c) may be performed simultaneously. The protective film may contain phosphorus-oxygen bonds and / or phosphorus-silicon bonds.

[0029] In one exemplary embodiment, the processing gas may include fluorine-containing gas and phosphorus-containing gas.

[0030] In one exemplary embodiment, the processing gas may contain at least one of PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3 and PBr5 as a phosphorus-containing molecule.

[0031] In one exemplary embodiment, the process gas may also contain hydrocarbons, hydrofluorocarbons, or fluorocarbons.

[0032] In one exemplary embodiment, a pulse wave including an electrically biased pulse can be periodically applied to a lower electrode within a substrate support that supports the substrate in step (b). The frequency defining the period of the pulse wave can be 1 Hz or more and 100 kHz or less. The proportion of the time during which the electrically biased pulse is applied to the lower electrode within the duration of the pulse wave period can be 50% or more and 99% or less. The electrical bias can be high-frequency power, and the level of the high-frequency power in the electrically biased pulse can be 2 kW or more.

[0033] In one exemplary embodiment, at the start of process (b), the temperature of the substrate can be set to a temperature below 0°C.

[0034] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a gas supply unit, and a plasma generation unit. The substrate support is configured to support a substrate within the chamber. The substrate includes a silicon-containing film and a mask. The mask contains carbon. The gas supply unit is configured to supply a processing gas for etching the silicon-containing film into the chamber. The processing gas includes a halogen element and phosphorus. The plasma generation unit is configured to generate plasma from the processing gas within the chamber to etch the silicon-containing film and form carbon-phosphorus bonds on the surface of the mask. The halogen element may be fluorine.

[0035] In another exemplary embodiment, an etching method is provided. The etching method includes a step (a1) of preparing a substrate. The substrate includes a silicon-containing film and a mask disposed on the silicon-containing film. The etching method further includes a step (b1) of deactivating sidewalls of openings in the silicon-containing film by supplying a phosphorus chemical species to the substrate. The etching method further includes a step (c1) of etching the silicon-containing film by supplying a halogen chemical species to the substrate.

[0036] In the etching method of the above embodiments, the sidewalls of the silicon-containing film are deactivated (or passivated) by phosphorus. That is, the sidewalls are passivated. Therefore, according to the etching method of the above embodiments, the sidewalls are protected to suppress lateral etching into the silicon-containing film during plasma etching of the silicon-containing film. Therefore, according to the etching method of the above embodiments, it becomes possible to protect the substrate when performing plasma etching on the silicon-containing film.

[0037] In one exemplary embodiment, the mask may contain carbon. In step (b1), carbon-phosphorus bonds may be formed on the surface of the mask.

[0038] In one exemplary embodiment, the silicon-containing film may include a silicon oxide film, and in step (b1), phosphorus-oxygen bonds may be formed on the sidewall surface.

[0039] In one exemplary embodiment, process (b1) and process (c1) can be performed simultaneously.

[0040] In one exemplary embodiment, steps (b1) and (c1) can be performed repeatedly.

[0041] In one exemplary embodiment, steps (b1) and (c1) can be performed with the substrate contained within the cavity of the plasma processing apparatus.

[0042] In one exemplary embodiment, phosphorus chemical species can be generated by generating a plasma containing phosphorus gas, and halogen chemical species can be generated by generating a plasma containing halogen gas.

[0043] In one exemplary embodiment, the halogen-containing gas may include a fluorine-containing gas. In one exemplary embodiment, the fluorine-containing gas may include at least one of hydrogen fluoride, iodine fluoride, and fluorocarbons.

[0044] In one exemplary embodiment, the phosphorus-containing gas may not contain fluorine. In one exemplary embodiment, the phosphorus-containing gas may contain PCl3 or POCl3.

[0045] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a gas supply unit, a plasma generation unit, and a control unit. The substrate support is configured to support a substrate within the chamber. The substrate includes a silicon-containing film and a mask disposed on the silicon-containing film. The gas supply unit is configured to supply phosphorus-containing gas and halogen-containing gas into the chamber. The plasma generation unit is configured to generate plasma from the gas within the chamber. The control unit is configured to control the gas supply unit and the plasma generation unit. The control unit controls the gas supply unit and the plasma generation unit to supply phosphorus-containing gas into the chamber and generate plasma from the phosphorus-containing gas in order to generate phosphorus chemical species that inactivate the sidewall surfaces of openings in the silicon-containing film. The control unit also controls the gas supply unit and the plasma generation unit to supply halogen-containing gas into the chamber and generate plasma from the halogen-containing gas in order to generate halogen chemical species that etch the silicon-containing film.

[0046] In yet another exemplary embodiment, an etching method is provided. The etching method includes a step (a2) in which a substrate is prepared within a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film. The etching method further includes a step (b2) in which the silicon-containing film is etched by chemical species from a plasma generated in the chamber by a process gas. The process gas includes halogen elements and phosphorus.

[0047] According to the above embodiment, a protective film comprising silicon and phosphorus contained in the processing gas is formed on the sidewall surface, the sidewall surface being divided by openings formed in the silicon-containing film by etching. The silicon-containing film is etched while the sidewall surface is protected by this protective film. Therefore, it becomes possible to suppress lateral etching during plasma etching of the silicon-containing film.

[0048] In one exemplary embodiment, the etching method may further include a step (c2) of forming a protective film on the sidewall surface that divides the opening formed by etching in step (b2). The protective film contains phosphorus contained in the process gas. Steps (b2) and (c2) may be performed simultaneously.

[0049] In one exemplary embodiment, the processing gas may contain at least one of PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3 and PBr5 as a phosphorus-containing molecule.

[0050] In one exemplary embodiment, the processing gas may also contain carbon and hydrogen.

[0051] In one exemplary embodiment, the processing gas may include H2, HF, and C. x H y C s H t Fu At least one of NH3 is a molecule containing hydrogen. Where x, y, s, t, and u are natural numbers.

[0052] In one exemplary embodiment, the halogen element can be fluorine.

[0053] In one exemplary embodiment, the processing gas may also contain oxygen.

[0054] In one exemplary embodiment, the silicon-containing film may be a silicon-containing dielectric film.

[0055] In one exemplary embodiment, the silicon-containing film may include at least one of a silicon oxide film, a silicon nitride film, and a silicon film.

[0056] In one exemplary embodiment, the silicon-containing film may include two or more silicon-containing films having different types of films from each other.

[0057] In one exemplary embodiment, the two or more silicon-containing films may include a silicon oxide film and a silicon nitride film. Alternatively, the two or more silicon-containing films may include a silicon oxide film and a silicon film. Alternatively, the two or more silicon-containing films may include a silicon oxide film, a silicon nitride film, and a silicon film.

[0058] In one exemplary embodiment, the substrate may also have a mask disposed on a silicon-containing film.

[0059] In one exemplary embodiment, the temperature of the substrate can be set to below 0°C at the start of process (b2).

[0060] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a gas supply unit, and a high-frequency power supply. The substrate support is configured to support a substrate within the chamber. The gas supply unit is configured to supply a processing gas for etching a silicon-containing film into the chamber. The processing gas includes a halogen element and phosphorus. The high-frequency power supply is configured to generate high-frequency power to generate plasma within the chamber from the processing gas.

[0061] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, the same or equivalent parts are labeled with the same symbols.

[0062] Figure 1 This is a flowchart of an exemplary embodiment of an etching method. Figure 1 The etching method shown (hereinafter referred to as "Method MT") is applicable to substrates having a silicon-containing film. In Method MT, the silicon-containing film is etched.

[0063] Figure 2 It is applicable Figure 1 A partially enlarged cross-sectional view of a substrate for an example of the etching method shown. Figure 2 The substrate W shown can be used in the manufacture of devices such as DRAM and 3D-NAND. The substrate W has a silicon-containing film SF. The substrate W may also have a substrate region UR. The silicon-containing film SF can be disposed on the substrate region UR. The silicon-containing film SF can be a silicon-containing dielectric film. The silicon-containing dielectric film can include a silicon oxide film or a silicon nitride film. The silicon-containing dielectric film can be a film containing silicon, or it can be a film of other film types. Furthermore, the silicon-containing film SF can include a silicon film (e.g., a polycrystalline silicon film). Furthermore, the silicon-containing film SF can include at least one of a silicon nitride film, a polycrystalline silicon film, a silicon carbon film, and a low-dielectric-constant film. The silicon carbon film can include a SiC film and / or a SiOC film. The low-dielectric-constant film contains silicon and can be used as an interlayer insulating film. Furthermore, the silicon-containing film SF can include two or more silicon-containing films having different film types from each other. The two or more silicon-containing films can include a silicon oxide film and a silicon nitride film. The silicon-containing film SF can be, for example, a multilayer film comprising one or more alternating layers of silicon oxide films and one or more silicon nitride films. Alternatively, two or more silicon-containing films may comprise silicon oxide films and silicon films. The silicon-containing film SF can be, for example, a multilayer film comprising one or more alternating layers of silicon oxide films and one or more silicon films. Alternatively, the silicon-containing film SF can be a multilayer film comprising multiple alternating layers of silicon oxide films and multiple polycrystalline silicon films. Alternatively, two or more silicon-containing films may comprise silicon oxide films, silicon nitride films, and silicon films.

[0064] The substrate W may also have a mask MK. The mask MK is disposed on a silicon-containing film SF. The mask MK is formed of a material having an etching rate lower than that of the silicon-containing film SF in process ST2. The mask MK may be formed of an organic material. That is, the mask MK may contain carbon. The mask MK may be formed, for example, of an amorphous carbon film, a photoresist film, or a spin-coated carbon film (SOC film). Alternatively, the mask MK may be formed of a silicon-containing film such as a silicon-containing antireflective film. Alternatively, the mask MK may be a metal-containing mask formed of a metal-containing material such as titanium nitride, tungsten, or tungsten carbide. The mask MK may have a thickness of 3 μm or more.

[0065] The mask MK is patterned. That is, the mask MK has a pattern that is transferred onto the silicon-containing film SF in step ST2. If the pattern of the mask MK is transferred onto the silicon-containing film SF, openings (recesses) such as holes or trenches are formed on the silicon-containing film SF. In step ST2, the aspect ratio of the openings formed on the silicon-containing film SF can be 20 or more, or 30 or more, 40 or more, or 50 or more. In addition, the mask MK can have line and spatial patterns.

[0066] In the MT method, a plasma treatment device is used for etching the silicon-containing SF film. Figure 3This is a diagram schematically illustrating a plasma processing apparatus according to an exemplary embodiment. Figure 3 The plasma processing apparatus 1 shown includes a chamber 10. The chamber 10 provides an internal space 10s within itself. The chamber 10 includes a chamber body 12. The chamber body 12 has a generally cylindrical shape. The chamber body 12 is formed, for example, of aluminum. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. The corrosion-resistant film can be formed of ceramics such as alumina or yttrium oxide.

[0067] A channel 12p is formed on the side wall of the chamber body 12. The substrate W is transported between the internal space 10s and the outside of the chamber 10 through the channel 12p. The channel 12p is opened and closed by a gate valve 12g. The gate valve 12g is provided along the side wall of the chamber body 12.

[0068] A support portion 13 is provided at the bottom of the chamber body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a generally cylindrical shape. The support portion 13 extends upward from the bottom of the chamber body 12 within the internal space 10s. The support portion 13 supports a substrate support 14. The substrate support 14 is configured to support the substrate W within the internal space 10s.

[0069] The substrate support 14 has a lower electrode 18 and an electrostatic chuck 20. The substrate support 14 may also have an electrode plate 16. The electrode plate 16 is formed of a conductor such as aluminum and has a generally disc-shaped form. The lower electrode 18 is disposed on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a generally disc-shaped form. The lower electrode 18 is electrically connected to the electrode plate 16.

[0070] An electrostatic chuck 20 is disposed on the lower electrode 18. A substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body and electrodes. The main body of the electrostatic chuck 20 has a generally disc-shaped shape and is formed of a dielectric. The electrodes of the electrostatic chuck 20 are film electrodes and are disposed within the main body of the electrostatic chuck 20. The electrodes of the electrostatic chuck 20 are connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the electrodes of the electrostatic chuck 20, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. The substrate W is attracted to the electrostatic chuck 20 by this electrostatic attraction and is held by the electrostatic chuck 20.

[0071] An edge ring 25 is disposed on the substrate support 14. The edge ring 25 is a ring-shaped component. The edge ring 25 can be formed of silicon, silicon carbide, or quartz, etc. The substrate W is disposed on the electrostatic chuck 20 and within the area surrounded by the edge ring 25.

[0072] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (e.g., refrigerant) is supplied to the flow path 18f from a cooler unit located outside the chamber 10 via a pipe 22a. The heat exchange medium supplied to the flow path 18f returns to the cooler 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.

[0073] A gas supply line 24 is provided in the plasma processing apparatus 1. The gas supply line 24 supplies heat transfer gas (e.g., He gas) from the 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.

[0074] The plasma processing apparatus 1 also includes an upper electrode 30. The upper electrode 30 is disposed above the substrate support 14. The upper electrode 30 is supported on the upper part of the chamber body 12 via a component 32. The component 32 is formed of an insulating material. The upper electrode 30 and the component 32 close the upper opening of the chamber body 12.

[0075] 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 of one side of the internal space 10s, and divides 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 vent holes 34a extending through the top plate 34 along its thickness direction.

[0076] The support body 36 can be detachably mounted and dismounted to support the top plate 34. The support body 36 is made of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support body 36. The support body 36 has a plurality of gas holes 36b extending downward from the gas diffusion chamber 36a. The plurality of gas holes 36b are respectively connected to a plurality of gas exhaust holes 34a. A gas inlet 36c is formed in the support body 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.

[0077] A gas source group 40 is connected to the gas supply pipe 38 via a flow controller group 41 and a valve group 42. The flow controller group 41 and the valve group 42 constitute the gas supply unit. The gas supply unit may also include the gas source group 40. The gas source group 40 includes multiple gas sources. The multiple gas sources include the source of the process gas used in method MT. The flow controller group 41 includes multiple flow controllers. The multiple flow controllers of the flow controller group 41 are either mass flow controllers or pressure control flow controllers. The valve group 42 includes multiple on / off valves. The multiple gas sources of the gas source group 40 are respectively connected to the gas supply pipe 38 via the flow controllers corresponding to the flow controller group 41 and the on / off valves corresponding to the valve group 42.

[0078] In the plasma processing apparatus 1, a shielding element 46 is detachably provided along the inner wall of the chamber body 12 and the outer periphery of the support portion 13. The shielding element 46 prevents reaction byproducts from adhering to the chamber body 12. The shielding element 46 is constructed, for example, by forming a corrosion-resistant film on the surface of a base material formed of aluminum. The corrosion-resistant film can be formed of ceramics such as yttrium oxide.

[0079] A baffle 48 is provided between the support portion 13 and the side wall of the chamber body 12. The baffle 48 is constructed, for example, by forming a corrosion-resistant film (such as yttrium oxide) on the surface of a component made of aluminum. Multiple through holes are formed in the baffle 48. An exhaust port 12e is provided below the baffle 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 turbomolecular pump.

[0080] 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 source for generating 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 in the range of 27MHz to 100MHz. The high-frequency power supply 62 is connected to the lower electrode 18 via a matching device 66 and an electrode plate 16. The matching device 66 has circuitry for matching the impedance of the load side (lower electrode 18 side) of the high-frequency power supply 62 with the output impedance of the high-frequency power supply 62. In addition, the high-frequency power supply 62 can be connected to the upper electrode 30 via the matching device 66. The high-frequency power supply 62 constitutes an example of a plasma generation unit.

[0081] The bias power supply 64 is a power source for generating an electrical bias. The bias power supply 64 is electrically connected to the lower electrode 18. The electrical bias has a second frequency. The second frequency is lower than the first frequency. The second frequency is, for example, a frequency in the range of 400 kHz to 13.56 MHz. When used with high-frequency power (HF), the electrical bias is applied to the lower electrode 18 to introduce ions into the substrate W. When the electrical bias is applied to the lower electrode 18, the potential of the substrate W placed on the substrate support 14 varies within a period defined by the second frequency.

[0082] In one embodiment, the electrical bias can be a high-frequency power LF having a second frequency. When used in conjunction with high-frequency power HF, the high-frequency power LF serves as a high-frequency bias power for introducing ions into 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 adapter 68 and an electrode plate 16. The matching adapter 68 has circuitry for matching the impedance on the load side (lower electrode 18 side) of the bias power supply 64 with the output impedance of the bias power supply 64.

[0083] Furthermore, high-frequency power LF can be used instead of high-frequency power HF, meaning that plasma can be generated using only a single high-frequency power source. In this case, the frequency of the high-frequency power LF can be greater than 13.56 MHz (e.g., 40 MHz). Also, in this case, the plasma processing apparatus 1 may not include the high-frequency power supply 62 and the matching device 66. In this case, the bias power supply 64 constitutes an example of a plasma generation unit.

[0084] In another embodiment, the electrical bias can be a pulse wave of DC voltage. The DC voltage pulse wave is periodically generated and applied to the lower electrode 18. The period of the DC voltage pulse wave is defined by a second frequency. The period of the DC voltage pulse wave includes two periods. The DC voltage during one of the two periods is a negative DC voltage. The level (i.e., absolute value) of the DC voltage during one of the two periods is higher than the level (i.e., absolute value) of the DC voltage during the other period. The DC voltage during the other period can be either negative or positive. The level of the DC voltage during the other period can be zero. In this embodiment, the bias power supply 64 is connected to the lower electrode 18 via a low-pass filter and electrode plate 16.

[0085] In one embodiment, the bias power supply 64 can provide a continuous electrical bias wave to the lower electrode 18. That is, the bias power supply 64 can continuously provide electrical bias to the lower electrode 18. During the execution of step STP or steps ST2 and ST3 of method MT, the continuous electrical bias wave is applied to the lower electrode 18.

[0086] In another embodiment, the bias power supply 64 can provide an electrically biased pulse wave to the lower electrode 18. The electrically biased pulse wave can be applied to the lower electrode 18 periodically. The period of the electrically biased pulse wave is defined by a 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 other examples, the third frequency can be 5 Hz or more and 100 kHz or less.

[0087] The period of the bias pulse wave includes two periods: the H period and the L period. The bias level during the H period (i.e., the level of the bias pulse) is higher than the bias level during the L period. That is, the bias pulse wave can be applied to the lower electrode 18 by increasing or decreasing the bias level. The bias level during the L period can be greater than zero. Alternatively, the bias level during the L period can be zero. That is, the bias pulse wave can be applied to the lower electrode 18 by alternately switching the supply and stop supply of the bias to the lower electrode 18. Wherein, when the bias is a high-frequency power LF, the bias level is the power level of the high-frequency power LF. When the bias is a high-frequency power LF, the high-frequency power LF level in the bias pulse can be 2kW or higher. When the bias is a negative DC voltage pulse wave, the bias level is the effective value of the absolute value of the negative DC voltage. The duty cycle of the electrically biased pulse wave, that is, the proportion of period H in the period of the electrically biased pulse wave, is, for example, 1% or more and 80% or less. In another example, the duty cycle of the electrically biased pulse wave can be 5% or more and 50% or less. Alternatively, the duty cycle of the electrically biased pulse wave can be 50% or more and 99% or less. To perform steps ST2 and ST3 of method MT, the electrically biased pulse wave can be applied to the lower electrode 18.

[0088] In one embodiment, the high-frequency power supply 62 can supply a continuous wave of high-frequency power HF. That is, the high-frequency power supply 62 can continuously supply high-frequency power HF. During the execution of step STP or steps ST2 and ST3 of method MT, a continuous wave of high-frequency power HF can be supplied.

[0089] In another embodiment, the high-frequency power supply 62 can supply a pulse wave of high-frequency power HF. The pulse wave of high-frequency power HF can be supplied periodically. The period of the pulse wave of high-frequency power HF is defined by a 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, the H period and the L period. The power level of high-frequency power HF during the H period is higher than the power level of high-frequency power HF during the L period. The power level of high-frequency power HF during the L period can be greater than zero or zero.

[0090] Furthermore, the period of the high-frequency (HF) power pulse wave can be synchronized with the period of the electrically biased pulse wave. The H-period within the period of the HF power pulse wave can be synchronized with the H-period within the period of the electrically biased pulse wave. Alternatively, the H-period within the period of the HF power pulse wave may not be synchronized with the H-period within the period of the electrically biased pulse wave. The duration of the H-period within the period of the HF power pulse wave can be the same as or different from the duration of the H-period within the period of the electrically biased pulse wave.

[0091] In the plasma processing apparatus 1, gas is supplied to the internal space 10s from the gas supply unit. Furthermore, 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 electrical bias. The generated high-frequency electric field generates plasma from the gas in the internal space 10s.

[0092] The plasma processing apparatus 1 may also include a control unit 80. The control unit 80 may be a computer equipped with a processor, memory, and other storage units, input devices, a display device, and signal input / output interfaces. The control unit 80 controls each part of the plasma processing apparatus 1. In the control unit 80, the operator can use the input devices to input commands and manage the plasma processing apparatus 1. Furthermore, the control unit 80 can visualize and display the operating status of the plasma processing apparatus 1 via the display device. Moreover, the storage unit stores control programs and recipe data. The control program is executed by the processor to perform various processes within 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.

[0093] Refer again Figure 1 The following describes method MT, using plasma processing apparatus 1 suitable for method MT. Figure 2 The case of the substrate W shown will be used as an example for explanation. When using the plasma processing apparatus 1, the method MT can be executed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 by the 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 explained.

[0094] In the following description, except Figure 1 In addition, refer to Figure 4 (a) Figure 4 (b) and Figure 5 . Figure 4 (a) is applicable Figure 1 A partially enlarged cross-sectional view of a substrate illustrating an example of the etching method. Figure 4 (b) is a partially enlarged cross-sectional view of an example substrate etched by plasma generated from a phosphorus-free processing gas. Figure 5 This is an example timing diagram of an etching method according to an exemplary embodiment. Figure 5 In the diagram, the horizontal axis represents time. Figure 5In the diagram, the vertical axis represents the power level of the high-frequency power (HF), the electrical bias level, and the supply status of the processing gas. An "L" level for the HF indicates that no HF is being supplied or that the HF power level is lower than the level represented by "H". An "L" level for the electrical bias indicates that the electrical bias is not being applied to the lower electrode 18 or that the electrical bias level is lower than the level represented by "H". Furthermore, an "ON" state for the processing gas supply status indicates that processing gas is being supplied to the chamber 10, and an "OFF" state indicates that the supply of processing gas to the chamber 10 is stopped.

[0095] like Figure 1 As shown, method MT begins in step ST1. In step ST1, substrate W is prepared within chamber 10. Substrate W is placed on electrostatic chuck 20 within chamber 10 and held by electrostatic chuck 20. Additionally, substrate W may have a diameter of 300 mm.

[0096] In method MT, step STP is then performed. In step STP, plasma treatment is performed on substrate W. In step STP, plasma is generated from process gas within chamber 10. Method MT includes step ST2. Step ST2 is performed during the execution of step STP. Method MT may also include step ST3. Step ST3 is performed during the execution of step STP. Steps ST2 and ST3 may be performed simultaneously or independently of each other.

[0097] In step ST2, the silicon-containing film SF is etched in step STP using chemical species from the plasma generated by the process gas within chamber 10. In step ST3, the protective film PF is formed on the substrate W in step STP using chemical species from the plasma generated by the process gas within chamber 10. The protective film PF is formed on the sidewall surface that divides the opening formed on the silicon-containing film SF.

[0098] The processing gas used in the STP process contains halogen elements and phosphorus. The halogen element in the processing gas can be fluorine. That is, the processing gas can contain fluorine-containing gases. The processing gas can contain at least one halogen-containing molecule. The processing gas can contain at least one of fluorocarbons and hydrofluorocarbons as at least one halogen-containing molecule. Fluorocarbons are, for example, at least one of CF4, C2F6, C3F6, C3F8, C4F6, C4F8, and C5F8. Hydrofluorocarbons are, for example, at least one of CH2F2, CHF3, and CH3F.

[0099] The process gas may contain at least one phosphorus-containing molecule. That is, the process gas may contain at least one phosphorus-containing gas. The phosphorus-containing gas may be a gas containing both phosphorus and halogens. The phosphorus-containing molecule may be, for example, phosphorus tetraoxide (P₄O₃). 10Phosphorus oxides include tetraphosphorus octoxide (P4O8) and tetraphosphorus hexaoxide (P4O6). Tetraphosphorus decaoxide is sometimes called diphosphorus pentoxide (P2O5). Phosphorus-containing molecules can be molecules containing both phosphorus and halogens. Phosphorus-containing molecules can be 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). Phosphorus-containing molecules can be halogenated phosphoric acyl groups such as phosphorus fluoride (POF3), phosphorus chloride (POCl3), and phosphorus bromide (POBr3). Phosphorus-containing molecules can be phosphine (PH3), calcium phosphide (Ca3P2), phosphoric acid (H3PO4), sodium phosphate (Na3PO4), and hexafluorophosphate (HPF6), etc. Phosphorus-containing molecules can be fluorophosphine derivatives (H... x PF y In this case, the sum of x and y is 3 or 5. Examples of fluorophosphine molecules include HPF2 and H2PF3. The processing gas may contain one or more of the aforementioned phosphorus-containing molecules as at least one phosphorus-containing molecule. For example, the processing gas may contain at least one of PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3, and PBr5 as at least one phosphorus-containing molecule. Furthermore, if the phosphorus-containing molecules contained in the processing gas are liquid or solid, they can be vaporized by heating or the like and supplied to the chamber 10.

[0100] The processing gas used in process ST2 may also contain carbon and hydrogen. The processing gas may contain H2, hydrogen fluoride (HF), and hydrocarbons (C). x H y ), hydrofluorocarbons (C) s H t F u At least one of the following, NH3, is a molecule containing hydrogen. Hydrocarbons, for example, are CH4 or C3H6. The process gas may contain the above-mentioned hydrocarbons, the above-mentioned hydrofluorocarbons, and fluorocarbons (C... v F w At least one of the following is a carbon-containing molecule: x, y, s, t, u, v, and w. The process gas may also contain oxygen. The process gas may contain an oxygen-containing gas (e.g., O2). Alternatively, the process gas may not contain oxygen.

[0101] In one embodiment, the processing gas may comprise a first gas and a second gas. The first gas is a phosphorus-free gas. The first gas may contain halogen elements. The first gas may contain at least one halogen-containing molecule as described above. The first gas may also contain carbon and hydrogen. The first gas may also contain the aforementioned gas containing hydrogen molecules and / or the gas containing carbon molecules. The first gas may also contain oxygen. The first gas may contain O2 gas. Alternatively, the first gas may not contain oxygen. The second gas is a phosphorus-containing gas. The second gas may contain at least one phosphorus-containing molecule as described above.

[0102] In the process STP, the flow ratio of the second gas to the first gas can be set to be greater than 0 and less than 0.5. The flow ratio can be set to be greater than 0.075 and less than 0.3. The flow ratio can be set to be greater than 0.1 and less than 0.25.

[0103] In the STP process, the pressure of the gas inside chamber 10 is set to a specified pressure. In the STP process, the pressure of the gas inside chamber 10 can be set to a pressure of 10 mTorr (1.3 Pa) or higher and 100 mTorr (13.3 Pa) or lower. Furthermore, in the STP process, high-frequency power (HF) is supplied to generate plasma from the process gas inside chamber 10. For example... Figure 5 As shown by the solid line, a continuous wave of high-frequency power (HF) can be supplied in the STP process. High-frequency power (LF) can be used instead of high-frequency power (HF) in the STP process. Both high-frequency power (HF) and electrical bias can be supplied in the STP process. For example... Figure 5 As shown by the solid line, in the STP process, a continuous electrical bias wave can be applied to the lower electrode 18. The power level of the high-frequency power HF can be set to a level of 2kW or higher and 10kW or lower. The power level of the high-frequency power LF can be set to 2kW (2.83W / cm² in the power level per unit area of ​​the substrate W). 2 The power level is above 10kW (14.2W / cm² per unit area of ​​the substrate W). The high-frequency power LF level can be set to 10kW (14.2W / cm² per unit area of ​​the substrate W). 2 The level is above ).

[0104] To perform the STP process, the control unit 80 controls the gas supply unit to supply processing gas into the chamber 10. Furthermore, the control unit 80 controls the exhaust device 50 to set the pressure of the gas within the chamber 10 to a specified pressure. Additionally, the control unit 80 controls the plasma generation unit to generate plasma from the processing gas. In the plasma processing apparatus 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 electrical bias.

[0105] In one embodiment of the method MT, the temperature of the substrate W at the start of process ST2 (or process STP) can be set to a temperature of 0°C or below. If the temperature of the substrate W is set to this temperature, the etching rate of the silicon-containing film SF in process ST2 becomes higher. To set the temperature of the substrate W at the start of process ST2, the control unit 80 can control the cooler unit. Alternatively, the temperature of the substrate W during the execution of process ST2 (or process STP) can be a temperature of 200°C or below.

[0106] In one embodiment, method MT may further include step STT. Step STT is performed before step ST2 (or step STP). In step STT, the temperature of substrate W is set to a temperature below 0°C. The temperature of substrate W at the start of step ST2 is set in step STT. In step STT, in order to set the temperature of substrate W, control unit 80 may control the cooler unit.

[0107] In process ST2, the silicon-containing film SF is etched using halogen chemical species derived from the plasma generated from the processing gas. In one embodiment, the portion of the mask MK exposed across the entire region of the silicon-containing film SF is etched (see reference). Figure 4 (a)).

[0108] When the processing gas contains phosphorus-containing molecules such as PF3, which contain both phosphorus and halogen elements, the halogen chemical species derived from these molecules contribute to the etching of the silicon-containing SF film. Therefore, in process ST2, phosphorus-containing molecules such as PF3, which contain both phosphorus and halogen elements, increase the etching rate of the silicon-containing SF film.

[0109] Furthermore, when the mask MK contains carbon, carbon-phosphorus bonds are formed on the surface of the mask in process ST2. The carbon-phosphorus bonds formed on the surface of the mask MK have a higher bonding energy than the bonds between carbon atoms in the mask MK. Therefore, according to method MT, the mask MK is protected during plasma etching of the silicon-containing film SF. Furthermore, the shape degradation of the mask MK is suppressed during plasma etching of the silicon-containing film SF. Therefore, according to method MT, it becomes possible to protect the substrate during plasma etching of the film.

[0110] In one implementation, such as Figure 1 As shown, method MT may further include step ST3. In step ST3, a protective film PF is formed on a sidewall surface that divides the opening formed on the silicon-containing film SF by etching in step ST2 (see reference). Figure 4 (a)). The protective film PF is formed in process STP by chemical species from the plasma generated by the process gas within chamber 10. In one embodiment, process ST3 can be performed simultaneously with process ST2. Figure 4As shown in (a), in one embodiment, the protective film PF can be formed such that its thickness decreases along the depth direction of the opening formed on the silicon-containing film SF.

[0111] The protective film PF comprises silicon and phosphorus contained in the process gas used in the STP process. In one embodiment, the protective film PF may also comprise carbon and / or hydrogen contained in the process gas. In one embodiment, the protective film PF may also comprise oxygen contained in the process gas or in the silicon-containing film SF. In one embodiment, the protective film PF may comprise phosphorus-oxygen bonds.

[0112] Figure 6 (a) is a graph showing the XPS analysis results of the protective film PF formed in an experimental example of etching a silicon oxide film in the STP process. Figure 6 (b) is a graph showing the results of XPS analysis of the protective film PF formed in an experimental example where the silicon nitride film was etched in the STP process. Figure 6 (a) and Figure 6 (b) Represents the P2p spectrum. The conditions for the STP process in the experimental example are shown below.

[0113] <Conditions for STP process>

[0114] The gas pressure inside chamber 10: 100 mTorr (13.33 Pa)

[0115] Processed gases: PF3 gas at 50 sccm and Ar gas at 150 sccm

[0116] High-frequency power HF (continuous wave): 40MHz, 4500W

[0117] High-frequency power LF (continuous wave): 400kHz, 7000W

[0118] The temperature of the substrate (the temperature of the substrate support before etching begins): -70℃

[0119] The execution time of process STP is 30 seconds.

[0120] Based on an experimental example where a silicon oxide film was etched in the STP process, the XPS analysis results of the protective film PF are as follows: Figure 6 As shown in (a), Si-O bonding peaks and PO bonding peaks were observed. Furthermore, based on an experimental example where the silicon nitride film was etched in the STP process, the XPS analysis results of the protective film PF were obtained, as shown... Figure 6 As shown in (b), Si-P bonding peaks and PN bonding peaks were observed.

[0121] If the gas being processed does not contain phosphorus, then as follows Figure 4 As shown in (b), the silicon-containing film SF is also etched laterally. As a result, the width of the openings formed on the silicon-containing film SF becomes locally wider. For example, the width of the openings formed on the silicon-containing film SF becomes locally wider near the mask MK.

[0122] On the other hand, in method MT, a protective film PF is formed on the sidewall surface that divides the opening formed on the silicon-containing film SF by etching. The silicon-containing film SF is etched while the sidewall surface is protected by this protective film PF. Therefore, according to method MT, it becomes possible to suppress lateral etching during plasma etching of the silicon-containing film SF.

[0123] In one embodiment, during the continued execution of process STP, i.e., during the period when plasma is generated from the process gas in process STP, one or more cycles, each including process ST2 and process ST3, can be executed sequentially. Two or more cycles can be executed sequentially in process STP.

[0124] In one implementation, such as Figure 5 As shown by the dashed lines, the electrically biased pulse wave described above can be applied from the bias power supply 64 to the lower electrode 18 in process STP. That is, when plasma generated by the process gas is present in chamber 10, the electrically biased pulse wave can be applied from the bias power supply 64 to the lower electrode 18. In this embodiment, the etching of the silicon-containing film SF in process ST2 is mainly generated during period H within the period of the electrically biased pulse wave. Furthermore, the formation of the protective film PF in process ST3 is mainly generated during period L within the period of the electrically biased pulse wave.

[0125] Furthermore, when the electrical bias is set to high-frequency power (LF), the power level of the high-frequency power (LF) can be set to 2kW or higher during the H period of the electrical bias pulse wave period. During the H period of the electrical bias pulse wave period, the power level of the high-frequency power (LF) can be set to 10kW or higher.

[0126] In one implementation, such as Figure 5 As shown by the dashed line, a pulse wave of the aforementioned high-frequency power (HF) can be supplied in process STP. During the H period of the HF pulse wave's cycle, the power level of the HF can be set to a level of 1kW or more and 10kW or less. For example... Figure 5 As shown, the period of a high-frequency power (HF) pulse wave can be synchronized with the period of an electrically biased pulse wave. For example... Figure 5As shown, the H-period in the period of the high-frequency power (HF) pulse wave can be synchronized with the H-period in the period of the electrically biased pulse wave. Alternatively, the H-period in the period of the HF pulse wave can be unsynchronized with the H-period in the period of the electrically biased pulse wave. The duration of the H-period in the period of the HF pulse wave can be the same as or different from the duration of the H-period in the period of the electrically biased pulse wave.

[0127] Figure 7 This is another timing diagram regarding an etching method according to an exemplary embodiment. Figure 7 In the diagram, the horizontal axis represents time. Figure 7 In the diagram, the vertical axis represents the power level of the high-frequency power HF, the electrical bias level, the supply status of the first gas, and the supply status of the second gas. An "L" level for the high-frequency power HF indicates that high-frequency power HF is not supplied or that the power level of the high-frequency power HF is lower than the power level represented by "H". An "L" level for the electrical bias indicates that the electrical bias is not applied to the lower electrode 18 or that the electrical bias level is lower than the level represented by "H". Furthermore, an "ON" state for the first gas supply status indicates that the first gas is supplied to the chamber 10, and an "OFF" state for the first gas supply status indicates that the supply of the first gas to the chamber 10 is stopped. Similarly, an "ON" state for the second gas supply status indicates that the second gas is supplied to the chamber 10, and an "OFF" state for the second gas supply status indicates that the supply of the second gas to the chamber 10 is stopped.

[0128] like Figure 7 As shown, in process STP, the first gas and the second gas can be supplied to the chamber 10 alternately. The etching of the silicon-containing film SF in process ST2 is mainly produced during the period when the first gas is supplied to the chamber 10. Furthermore, the formation of the protective film PF in process ST3 is mainly produced during the period when the second gas is supplied to the chamber 10.

[0129] like Figure 7 As shown by the solid line, a continuous wave of high-frequency power (HF) can be supplied in the STP process. Alternatively, with... Figure 5 Similarly, in the STP process, a high-frequency power HF pulse wave can be supplied, just as the pulse wave of HF is shown. The high-frequency power HF pulse wave in... Figure 7 The dashed lines represent the period. The H period within the period of the high-frequency power HF pulse wave is synchronized with or partially repeats the period during which the first gas is supplied to the chamber 10. Furthermore, the L period within the period of the high-frequency power HF pulse wave is synchronized with or partially repeats the period during which the second gas is supplied to the chamber 10.

[0130] And, as Figure 7 As shown by the solid line, in the STP process, a continuous wave of electrical bias can be applied to the lower electrode 18. Alternatively, with... Figure 5 Similarly, in the STP process, the electrically biased pulse wave shown can be applied to the lower electrode 18. The electrically biased pulse wave in... Figure 7 The period is represented by a dashed line. The H period within the period of the electrically biased pulse wave is synchronized with or partially repeats the period during which the first gas is supplied to the chamber 10. Furthermore, the L period within the period of the electrically biased pulse wave is synchronized with or partially repeats the period during which the second gas is supplied to the chamber 10.

[0131] The following is for reference. Figure 8 , Figure 9 (a) and Figure 9 (b) Figure 8 This is a top view of another example of a substrate. Figure 9 (a) is along Figure 8 A sectional view cut along line IXA-IXA. Figure 9 (b) is along Figure 8 A cross-sectional view taken along the IXB-IXB line. The substrate of the MT substrate can have, for example... Figure 8 , Figure 9 (a) and Figure 9 (b) The mask MK is like the substrate W shown. That is, the mask of the substrate to which method MT is applied may include a portion of the silicon-containing film SF in which the mask occupies a high proportion relative to the openings divided by the mask and a portion therein in which the mask occupies a low proportion.

[0132] Figure 8 , Figure 9 (a) and Figure 9 (b) The substrate W shown has a mask MK containing carbon. The mask MK is formed, for example, from an amorphous carbon film, a photoresist film, or a spin-coated carbon film (SOC film).

[0133] exist Figure 8 , Figure 9 (a) and Figure 9 (b) In the substrate W shown, the mask MK divides a plurality of openings OP. The mask MK includes a portion MKA on the silicon-containing film SF that has a high proportion relative to the openings OP divided by the mask MK and a portion MKB that has a low proportion. The portion MKA that has a high proportion relative to the openings OP is a densely formed portion of the mask MK, i.e., a dense region. The portion MKB that has a low proportion relative to the openings OP is a roughly formed portion of the mask MK, i.e., a rough region. Furthermore, this "proportion" is either the proportion of the area of ​​the mask MK per unit area on the silicon-containing film SF, or the proportion of the length of the mask MK per unit length on the silicon-containing film SF.

[0134] like Figure 8As shown, the multiple openings OP can each have a rectangular planar shape. Alternatively, the multiple openings OP can each have other planar shapes such as circles or ellipses. Figure 8 As shown, multiple openings (OPs) can be arranged in two dimensions to provide multiple rows and multiple columns of openings. In Figure 8 , Figure 9 (a) and Figure 9 (b) In the substrate W shown, part of MKA includes a mask MK pattern in one of the row and column directions of the above arrangement, and part of MKB includes a mask MK pattern in the other direction.

[0135] Typically, for a mask MK in a rough region, more etching is performed by plasma etching with a silicon-containing film SF than for a mask MK in a dense region. Figure 8 , Figure 9 (a) and Figure 9 (b) In the substrate W shown, if the mask MK in the rough region is etched more than the mask MK in the dense region, the shape of the line LN will deform due to the internal stress of the mask MK. If the shape of the line LN is deformed, the LER (Line Edge Roughness) and LWR (Line Width Roughness) of the line LN will increase. However, in method MT, the carbon in the mask MK is bonded to phosphorus from the plasma generated in process STP, forming on the surface of the mask MK. The carbon-phosphorus bond formed on the surface of the mask MK has a higher bonding energy than the bond between carbons in the mask MK. Therefore, during the etching of the silicon-containing film SF in process ST2, in method MT, the carbon-phosphorus bond formed on the surface of the mask MK protects the mask MK. Therefore, according to method MT, it becomes possible to protect the substrate W during plasma etching of the silicon-containing film SF. Furthermore, the carbon-phosphorus bond formed on the surface of the mask MK reduces the amount of etching of the mask MK in the rough region. As a result, the difference between the etching amount of the mask MK in the rough region and the etching amount of the mask MK in the dense region is reduced. Consequently, the shape degradation of the mask MK having both rough and dense regions is suppressed.

[0136] The following describes the first experiment conducted to evaluate the method MT. In the first experiment, samples with the same characteristics as those used in the experiment were prepared. Figure 2Multiple sample substrates with the same structure as the substrate W shown are presented. Each sample substrate has a silicon oxide film and a mask disposed on the silicon oxide film. The mask is a mask formed of an amorphous carbon film. In the first experiment, the STP process of method MT was applied to the multiple sample substrates. The processing gas used for each of the multiple sample substrates contained PF3 gas at different flow rates. Another condition in the STP process is shown below. In addition, the flow rates of PF3 gas are 0 sccm, 15 sccm, 30 sccm, 50 sccm, and 100 sccm, respectively. That is, in the first experiment, the flow rate ratios of the second gas to the first gas are 0, 0.075, 0.15, 0.25, and 0.5, respectively.

[0137] <Conditions for STP process>

[0138] The gas pressure inside chamber 10: 25 mTorr (3.3 Pa)

[0139] Gases processed: CH4 at 50 sccm, CF4 at 100 sccm, and O2 at 50 sccm

[0140] High-frequency power HF (continuous wave): 40MHz, 4500W

[0141] High-frequency power LF (continuous wave): 400kHz, 7000W

[0142] Sample substrate temperature (substrate support temperature before etching begins): -30℃

[0143] The execution time of process STP: 600 seconds

[0144] In Experiment 1, for each of the multiple sample substrates, the etching rate of the silicon oxide film, the maximum width of the opening formed on the silicon oxide film, and the selectivity were determined. The selectivity was obtained by dividing the etching rate of the silicon oxide film by the etching rate of the mask. In Experiment 1, the relationship between the flow rate of PF3 gas in the process gas used in the STP process and the etching rate of the silicon oxide film was determined. Furthermore, the relationship between the flow rate of PF3 gas in the process gas used in the STP process and the maximum width of the opening formed on the silicon oxide film was determined. Furthermore, the relationship between the flow rate of PF3 gas in the process gas used in the STP process and the selectivity was determined. The relationship between the flow rate of PF3 gas in the process gas and the etching rate of the silicon oxide film is shown below. Figure 10 Furthermore, the relationship between the flow rate of PF3 gas in the treatment gas and the maximum width of the opening formed on the silicon oxide film is shown in [the figure]. Figure 11 Furthermore, the relationship between the flow rate of PF3 gas in the treated gas and the selectivity ratio is shown in the figure. Figure 12 middle.

[0145] like Figure 10 and Figure 12 As shown, it was confirmed that when the processing gas contains phosphorus, i.e., when the flow ratio of the second gas to the first gas is greater than 0, the etching rate and selectivity of the silicon oxide film increase. Furthermore, as... Figure 12 As shown, it was confirmed that a considerably high selectivity ratio can be obtained when the flow rate of PF3 gas in the processed gas is 15 sccm or more and 60 sccm or less or 50 sccm or less. That is, it was confirmed that a considerably high selectivity ratio can be obtained when the flow rate ratio is 0.075 or more and 0.3 or less or 0.25 or less. Furthermore, as... Figure 10 As shown, it was confirmed that when the flow rate of PF3 gas in the processing gas is 20 sccm or more, that is, when the flow ratio is 0.1 or more, the etching rate is about 1.5 times that when no PF3 is added.

[0146] And, as Figure 11 As shown, it was confirmed that when the process gas contains phosphorus, the maximum width of the opening in the silicon oxide film can be suppressed from decreasing, i.e., the width of the opening in the silicon oxide film locally widens. In particular, it was confirmed that when the flow rate of PF3 gas in the process gas is 50 sccm or more, the local widening of the opening width in the silicon oxide film can be suppressed more significantly.

[0147] The following describes the second experiment conducted to evaluate the method MT. In the second experiment, samples with the same characteristics as those used in the experiment were prepared. Figure 8 , Figure 9 (a) and Figure 9 (b) shows multiple sample substrates with the same structure as substrate W. Each sample substrate has a silicon oxide film and a mask disposed on the silicon oxide film. The mask is a mask formed of an amorphous carbon film. In Experiment 2, the STP process of Method MT was applied to the multiple sample substrates. The processing gas used for each of the multiple sample substrates contained PF3 gas at different flow rates. The other conditions of the STP process in Experiment 2 were the same as those of the STP process in Experiment 1.

[0148] In Experiment 2, the LER and LWR of the line LN of the mask MK on the substrate W after the STP process were determined. The relationship between the flow rate of PF3 gas in the processing gas and LER and LWR, determined in Experiment 2, is shown below. Figure 13 In the middle. For example Figure 13 As shown, it was confirmed that LER and LWR decreased with increasing PF3 gas flow rate in the process gas. That is, it was confirmed that the shape degradation of the mask MK decreased with increasing PF3 gas flow rate in the process gas.

[0149] The following describes an etching method according to another exemplary embodiment. In the following description, reference is made to... Figure 14 , Figure 15 (a) Figure 15 (b) and Figure 15 (c) Figure 14 This is a flowchart of an etching method (hereinafter referred to as "method MT2") according to another exemplary embodiment. Figure 15 (a) is a partial enlarged cross-sectional view of an example substrate in the state of process ST22 of method MT2. Figure 15 (b) is a partial enlarged cross-sectional view of an example substrate in the state of process ST23 of method MT2. Figure 15 (c) is a partially enlarged cross-sectional view of an example substrate after the application of method MT2. Hereinafter, the case of performing method MT2 using plasma processing apparatus 1 will be described as an example.

[0150] Figure 14 The method shown in MT2 can be applied to, for example... Figure 2 The substrate shown has a silicon film SF and a mask MK. Method MT2 begins in step ST21. Step ST21 is the same as step ST1 in method MT1. In step ST21, the substrate W is prepared in chamber 10. The substrate W is placed on an electrostatic chuck 20 in chamber 10 and held by the electrostatic chuck 20. Steps ST22, ST23, and ST24 of method MT2 can be performed with the substrate W contained in chamber 10.

[0151] In method MT2, step ST22 is performed after step ST21. In step ST22, the silicon-containing film SF is etched. In step ST22, as... Figure 15 As shown in (a), halogen chemical species are supplied to the substrate W to locally etch a silicon-containing film SF. The halogen chemical species are, for example, ions. Figure 15 In (a), it is represented by the circle surrounding the "+".

[0152] The halogenated chemical species used in process ST22 are supplied by plasma generated from the etching gas. The etching gas contains halogenated gases. The halogenated gases may contain fluorine-containing gases. The fluorine-containing gases may contain at least one of hydrogen fluoride, nitrogen trifluoride (NF3), sulfur hexafluoride (SF6), the aforementioned fluorocarbons, and the aforementioned hydrofluorocarbons. The etching gas containing fluorocarbons can be used when the silicon-containing film SF includes a silicon oxide film. The etching gas containing hydrofluorocarbons can be used when the silicon-containing film SF includes a silicon nitride film. When the silicon-containing film SF includes polycrystalline silicon, the halogenated gas may contain halogenated gases such as Cl2 gas. The etching gas, as described in the first gas above, may also contain carbon and hydrogen. The etching gas may also contain the aforementioned gases containing hydrogen molecules and / or gases containing carbon molecules. The etching gas may also contain oxygen. The etching gas may contain O2 gas.

[0153] To execute process ST22, the control unit 80 controls the gas supply unit to supply etching gas into the chamber 10. Furthermore, the control unit 80 controls the exhaust device 50 to set the pressure of the gas within the chamber 10 to a specified pressure. Additionally, the control unit 80 controls the plasma generation unit to generate plasma from the etching gas within the chamber 10. In the plasma processing apparatus 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 electrical bias.

[0154] In method MT2, operations ST23 and ST24 are executed sequentially after operation ST22. In operation ST23, as follows... Figure 15 As shown in (b), phosphorus chemical species are supplied to the substrate W. These phosphorus chemical species are, for example, phosphorus-active species such as ions and / or free radicals. Figure 15 In (b), it is represented by the circle surrounding "P". In process ST23, as... Figure 15 As shown in (b), bonds between the elements contained in the silicon-containing film SF and phosphorus are formed on the sidewalls of the openings in the silicon-containing film SF. When the silicon-containing film SF contains a silicon oxide film, phosphorus-oxygen bonds are formed on the sidewalls of the silicon-containing film SF. In step ST23, the sidewalls of the silicon-containing film SF are deactivated (or passivated) due to the phosphorus chemical species. That is, passivation of the sidewalls of the silicon-containing film SF is performed. Furthermore, when the mask MK contains carbon, carbon-phosphorus bonds can be formed on the surface of the mask MK in step ST23.

[0155] The phosphorus chemical species used in step ST23 are supplied by plasma generated from the passivation gas. The passivation gas used in step ST23 contains a phosphorus-containing gas. The phosphorus-containing gas contains at least one phosphorus-containing molecule as described above. In one embodiment, the phosphorus-containing gas may not contain fluorine. This phosphorus-containing gas may contain PCl3 or POCl3.

[0156] To execute step ST23, the control unit 80 controls the gas supply unit to supply passivating gas into the chamber 10. Furthermore, the control unit 80 controls the exhaust device 50 to set the pressure of the gas within the chamber 10 to a specified pressure. Additionally, the control unit 80 controls the plasma generation unit to generate plasma from the passivating gas within the chamber 10. In the plasma processing apparatus 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 electrical bias.

[0157] In step ST24, the silicon-containing film SF is further etched. Step ST24 is the same as step ST22. That is, in step ST24, the silicon-containing film SF is etched by halogen chemical species supplied by plasma generated from the etching gas.

[0158] In one embodiment, steps ST23 and ST24 can be performed alternately and repeatedly. In this case, method MT2 may further include step ST25. In step ST25, it is determined whether a stopping condition is met. In step ST25, the stopping condition is determined to be met, for example, if the number of repetitions of the loop including steps ST23 and ST24 reaches a predetermined number. If it is determined in step ST25 that the stopping condition is not met, the loop is executed again. On the other hand, if it is determined in step ST25 that the stopping condition is met, method MT2 ends. If method MT2 ends, then... Figure 15 As shown in (c), the base region UR can be exposed.

[0159] Furthermore, the phosphorus chemical species used in step ST23 can be supplied by plasma generated at a location away from the chamber in which the substrate W is housed. Also, the plasma processing apparatus used in step ST23 and the plasma processing apparatus used in step ST24 can be different from each other. In this case, the substrate W can be transferred between the plasma processing apparatus used in step ST23 and the plasma processing apparatus used in step ST24 only through a depressurized space (i.e., without disrupting the vacuum).

[0160] The following describes an etching method according to yet another exemplary embodiment. In the following description, reference is made to... Figure 16 , Figure 17 (a) and Figure 17 (b) Figure 16 This is a flowchart of an etching method (hereinafter referred to as "Method MT3") of another exemplary embodiment. Figure 17 (a) is a partial enlarged cross-sectional view of a substrate in the state of process STP3 of the applicable method MT3. Figure 17(b) is a partially enlarged cross-sectional view of an example substrate after the application of method MT3. Hereinafter, the case of performing method MT3 using plasma processing apparatus 1 will be described as an example.

[0161] Figure 16 The method shown in MT3 can be applied to, for example... Figure 2 The substrate shown has a silicon film SF and a mask MK. Method MT3 begins in step ST31. Step ST31 is the same as step ST1 of method MT1. In step ST31, the substrate W is prepared in chamber 10. The substrate W is placed on an electrostatic chuck 20 in chamber 10 and held by the electrostatic chuck 20. Step STP3 of method MT3 is performed with the substrate W contained in chamber 10.

[0162] Operation STP3 includes concurrent operations ST33 and ST34. Operation ST33 is the same as operation ST23 in method MT2. In operation ST33, as... Figure 17 As shown in (a), phosphorus chemical species are supplied to the substrate W to passivate the sidewalls of the silicon-containing film SF. Figure 17 In (a), phosphorus chemical species are represented by a circle surrounding "P". Step ST34 is the same as step ST24 of method MT2. In step ST34, as... Figure 17 As shown in (a), halogen chemical species are supplied to the substrate W to etch the silicon-containing film SF. Figure 17 In (a), halogenated chemical species are represented by circles surrounding the "+".

[0163] In process STP3, in order to simultaneously perform processes ST33 and ST34, a plasma of processing gas is generated within chamber 10. Regarding the processing gas, it includes the passivation gas described above in conjunction with process ST23 and the etching gas described above in conjunction with process ST22.

[0164] To execute process STP3, the control unit 80 controls the gas supply unit to supply processing gas into the chamber 10. Furthermore, the control unit 80 controls the exhaust device 50 to set the pressure of the gas within the chamber 10 to a specified pressure. Additionally, the control unit 80 controls the plasma generation unit to generate plasma from the processing gas within the chamber 10. In the plasma processing apparatus 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 electrical bias.

[0165] In methods MT2 and MT3, the sidewalls of the silicon-containing film SF are deactivated (or passivated) by phosphorus. That is, passivation of the sidewalls is performed. Therefore, according to methods MT2 and MT3, the sidewalls are protected to suppress lateral etching into the silicon-containing film SF during plasma etching. Therefore, according to methods MT2 and MT3, it becomes possible to protect the substrate W during plasma etching of the silicon-containing film SF.

[0166] The above descriptions have illustrated various exemplary embodiments, but the embodiments are not limited to these exemplary embodiments. Various additions, omissions, substitutions, and modifications can be made. Furthermore, elements from different embodiments can be combined to form other embodiments.

[0167] For example, the plasma processing apparatus used in each of methods MT, MT2, and MT3 can be a capacitively coupled plasma processing apparatus other than plasma processing apparatus 1. Alternatively, the plasma processing apparatus used in each of methods MT, MT2, and MT3 can be a type of plasma processing apparatus other than capacitively coupled one. Such a plasma processing apparatus can 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, etc.

[0168] Furthermore, in addition to a bias power supply 64 that supplies high-frequency power LF to the lower electrode 18, the plasma processing apparatus may also have another bias power supply configured to intermittently or periodically apply pulses of negative polarity DC voltage to the lower electrode 18.

[0169] As can be understood from the above description, various embodiments of the present invention have been described in this specification for illustrative purposes, and various modifications can be made without departing from the scope and spirit of the invention. Therefore, the invention is not limited to the various embodiments disclosed in this specification, and the true scope and spirit are indicated by the appended claims.

Claims

1. An etching method, comprising: Step (a) involves preparing a substrate within a plasma processing apparatus chamber, wherein the substrate includes a silicon-containing film and a mask disposed on the silicon-containing film, the mask containing carbon; and Step (b) involves etching the silicon-containing film using chemical species from a plasma generated by a process gas within the chamber, wherein the process gas contains halogens and phosphorus. In (b), carbon and phosphorus bonds are formed on the surface of the mask.

2. The etching method according to claim 1, wherein, The silicon-containing film includes a silicon oxide film.

3. The etching method according to claim 1, wherein, The silicon-containing film also includes at least one of silicon nitride film, polycrystalline silicon film, silicon carbon film, and low dielectric constant film.

4. The etching method according to any one of claims 1 to 3, wherein, The mask includes a portion of the silicon-containing film in which the mask occupies a high proportion relative to the openings defined by the mask and a portion in which the proportion is low.

5. The etching method according to any one of claims 1 to 3, wherein, The mask has linear and spatial patterns.

6. The etching method according to any one of claims 1 to 3, further comprising step (c), which involves forming a protective film on the sidewall surface dividing the opening formed by etching in (b). The protective film contains phosphorus contained in the processed gas.

7. The etching method according to claim 6, wherein, (b) and (c) are performed simultaneously.

8. The etching method according to claim 6, wherein, The protective film contains phosphorus-oxygen bonds and / or phosphorus-silicon bonds.

9. The etching method according to any one of claims 1 to 3, wherein, The processing gas includes fluorine-containing gas and phosphorus-containing gas.

10. The etching method according to any one of claims 1 to 3, wherein, The processing gas contains at least one of PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3, and PBr5 as molecules containing phosphorus.

11. The etching method according to any one of claims 1 to 3, wherein, The processed gas also contains hydrocarbons, hydrofluorocarbons, or fluorocarbons.

12. The etching method according to any one of claims 1 to 3, wherein, In (b), a pulse wave including an electrically biased pulse is periodically applied to a lower electrode within a substrate support that supports the substrate.

13. The etching method according to claim 12, wherein, The period of the pulse wave is defined by a frequency of 1 Hz or higher and 100 kHz or lower.

14. The etching method according to claim 12, wherein, The proportion of the time during which the electrically biased pulse is applied to the lower electrode is more than 50% and less than 99% of the period of the pulse wave.

15. The etching method according to claim 12, wherein, The electrical bias is a high-frequency power, and the level of the high-frequency power in the pulse of the electrical bias is above 2kW.

16. The etching method according to any one of claims 1 to 3, wherein, At the beginning of (b), the temperature of the substrate is set to a temperature below 0°C.

17. A plasma processing apparatus comprising: Chamber; A substrate support, configured to support a substrate within the cavity, wherein... The substrate includes a silicon-containing film and a mask disposed on the silicon-containing film, the mask containing carbon; A gas supply unit configured to supply a processing gas for etching the silicon-containing film into the chamber, wherein the processing gas contains halogen elements and phosphorus; and A plasma generation unit is configured to generate plasma from the processing gas within the chamber to etch the silicon-containing film and form carbon-phosphorus bonds on the surface of the mask.

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