Etching method and etching apparatus

Abstract

The present invention provides a technology which enhances verticality with respect to etching. The present invention provides an etching method for etching a film to be etched in a plasma processing apparatus which is provided with a chamber and a substrate supporting member that is arranged within the chamber so as to support a substrate; and the etching method comprises a step in which a substrate that has the film to be etched is arranged on the substrate supporting member, a step in which a processing gas containing an HF gas is supplied into the chamber, a step in which a plasma of the processing gas is generated within the chamber by means of high-frequency waves having a first frequency, and an application step in which a pulse voltage is periodically applied to the substrate supporting member at a second frequency that is lower than the first frequency.

Description

Technical Field

[0001] Exemplary embodiments of the present disclosure relate to an etching method and an etching apparatus.

Background Art

[0002] Patent Document 1 discloses an etching method using a processing gas containing a hydrocarbon gas and a hydrofluorocarbon gas as a processing gas used for plasma etching.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique for enhancing perpendicularity in etching.

Means for Solving the Problems

[0005] In one exemplary embodiment of the present disclosure, an etching method for etching an etched film in an etching apparatus is provided. The etching apparatus includes a chamber and a substrate support provided in the chamber and configured to support the substrate. The etching method includes a step of disposing a substrate having the etched film on the substrate support, a step of supplying a processing gas containing HF gas into the chamber, a step of generating plasma of the processing gas in the chamber by a high frequency having a first frequency, and an applying step of periodically applying a pulse voltage to the substrate support at a second frequency lower than the first frequency.

[0006] In one exemplary embodiment of the present disclosure, an etching method for etching an etching target film in an etching apparatus is provided. The plasma processing apparatus includes a chamber and a substrate support provided in the chamber and configured to support the substrate. The etching method includes a step of disposing a substrate having the etching target film on the substrate support, a step of supplying a processing gas containing hydrogen and fluorine into the chamber, a step of generating plasma containing a chemical species of hydrogen fluoride from the processing gas in the chamber by a high frequency having a first frequency, and an applying step of periodically applying a pulse voltage to the substrate support at a second frequency lower than the first frequency.

[0007] In one exemplary embodiment of the present disclosure, an etching apparatus for etching an etching target film is provided. The etching apparatus includes a chamber, a gas supply unit configured to supply a processing gas to the chamber, and a control unit. The control unit disposes a substrate having the etching target film on the substrate support, supplies a processing gas containing HF gas into the chamber, generates plasma of the processing gas in the chamber by a high frequency having a first frequency, and executes control to periodically apply a pulse voltage to the substrate support at a second frequency lower than the first frequency.

Advantages of the Invention

[0008] According to one exemplary embodiment of the present disclosure, an etching method with high perpendicularity can be provided.

Brief Description of the Drawings

[0009]

Figure 1

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MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, each embodiment of the present disclosure will be described.

[0011] In one exemplary embodiment, an etching method for etching an etched film in an etching apparatus is provided. The etching apparatus includes a chamber and a substrate support provided in the chamber and configured to support a substrate. The etching method includes a step of disposing a substrate having an etched film on the substrate support, a step of supplying a processing gas containing HF gas into the chamber, a step of generating a plasma of the processing gas in the chamber by a high frequency having a first frequency, and an applying step of periodically applying a pulse voltage to the substrate support at a second frequency lower than the first frequency.

[0012] In one exemplary embodiment, the processing gas further includes a phosphorus-containing gas.

[0013] In one exemplary embodiment, the phosphorus-containing gas is PF 3 , PCl 3 , PF 5 , PCl 5 , POCl 3 , PH 3 , PBr 3 and PBr 5 and includes at least one selected from the group consisting of.

[0014] In one exemplary embodiment, the processing gas further includes C x H y F z (where x and z are integers of 1 or more, and y is an integer of 0 or more).

[0015] In one exemplary embodiment, the processing gas further includes a halogen element-containing gas.

[0016] In one exemplary embodiment, the pulsed voltage is a negative voltage.

[0017] In one exemplary embodiment, an etching method for etching an etched film in an etching apparatus is provided. The etching apparatus includes a chamber and a substrate support provided in the chamber and configured to support a substrate. The etching method includes a step of disposing a substrate having an etched film on the substrate support, a step of supplying a processing gas containing hydrogen and fluorine into the chamber, a step of generating a plasma containing a chemical species of hydrogen fluoride from the processing gas in the chamber by a high frequency having a first frequency, and an applying step of periodically applying a pulsed voltage to the substrate support at a second frequency lower than the first frequency.

[0018] In one exemplary embodiment, an etching apparatus for etching an etching target film is provided. The etching apparatus includes a chamber, a gas supply unit that supplies a processing gas to the chamber, and a control unit. The control unit disposes a substrate having an etching target film on a substrate support, supplies a processing gas containing HF gas into the chamber, generates a plasma of the processing gas in the chamber by a high frequency having a first frequency, and periodically applies a pulse voltage to the substrate support at a second frequency lower than the first frequency to execute control.

[0019] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or similar elements are denoted by the same reference numerals, and redundant descriptions are omitted. Unless otherwise specified, the positional relationships such as up, down, left, and right are described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and the actual ratios are not limited to the illustrated ratios.

[0020] <Configuration of Plasma Processing Apparatus 1> FIG. 1 is a diagram schematically showing a plasma processing apparatus 1 according to one exemplary embodiment. The plasma processing apparatus 1 can perform, for example, an etching process. Further, an etching method according to one exemplary embodiment (hereinafter referred to as "the present processing method") may be executed using the plasma processing apparatus 1.

[0021] The plasma processing apparatus 1 shown in FIG. 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein. The chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The chamber body 12 is 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 can be formed of a ceramic such as aluminum oxide or yttrium oxide.

[0022] A passage 12p is formed in the side wall of the chamber body 12. The substrate W is conveyed between the internal space 10s and the outside of the chamber 10 through the passage 12p. The passage 12p is opened and closed by a gate valve 12g. The gate valve 12g is provided along the side wall of the chamber body 12.

[0023] A support portion 13 is provided on the bottom of the chamber body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a substantially cylindrical shape. The support portion 13 extends upward from the bottom of the chamber body 12 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.

[0024] 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 formed of a conductor such as aluminum and has a substantially disk shape. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a substantially disk shape. The lower electrode 18 is electrically connected to the electrode plate 16.

[0025] 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 of a dielectric. The electrode of the electrostatic chuck 20 is a film-like electrode and is provided within 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 attraction 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 attraction force and is held by the electrostatic chuck 20.

[0026] An edge ring 25 is disposed on the substrate support 14. The edge ring 25 is a ring-shaped member. The edge ring 25 can be formed of silicon, silicon carbide, quartz, or the like. The substrate W is disposed on the electrostatic chuck 20 and within the region surrounded by the edge ring 25.

[0027] 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 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.

[0028] The plasma processing apparatus 1 is provided with a gas supply line 24. The gas supply line 24 supplies a heat transfer gas (e.g., 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.

[0029] 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 formed of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the chamber body 12.

[0030] The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 is the lower surface on the side of the internal space 10s and defines the internal space 10s. The top plate 34 can be formed of a low-resistance conductor or semiconductor that generates little Joule heat. The top plate 34 has a plurality of gas discharge holes 34a penetrating through the top plate 34 in its plate thickness direction.

[0031] The support 36 detachably supports the top plate 34. The support 36 is formed of a conductive material such as aluminum. Inside the support 36, a gas diffusion chamber 36a is provided. The support 36 has a plurality of gas holes 36b extending downward from the gas diffusion chamber 36a. The plurality of gas holes 36b communicate with the plurality of gas discharge holes 34a respectively. 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.

[0032] 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 constitute a gas supply unit. The gas supply unit may further include the gas source group 40. The gas source group 40 includes a plurality of gas sources. The plurality of gas sources include sources of process 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 on-off 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 on-off valve in the valve group 42.

[0033] In the plasma processing apparatus 1, a shield 46 is detachably provided along the inner wall surface of the chamber body 12 and the outer periphery of the support portion 13. The shield 46 prevents reaction by-products from adhering to the chamber body 12. The shield 46 is configured, for example, by forming a corrosion-resistant film on the surface of a base material formed of aluminum. The corrosion-resistant film can be formed of a ceramic such as yttrium oxide.

[0034] A baffle plate 48 is provided between the support part 13 and the side wall of the chamber body 12. The baffle plate 48 is configured, for example, by forming a corrosion-resistant film (such as a yttrium oxide film) 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 vacuum pump such as a pressure regulating valve and a turbo molecular pump.

[0035] 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 plasma generation. The first frequency is, for example, a frequency within the range of 27 MHz to 100 MHz. The high-frequency power supply 62 is connected to the lower electrode 18 via a matcher 66 and an electrode plate 16. The matcher 66 has a circuit for matching the impedance on 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. Incidentally, the high-frequency power supply 62 may be connected to the upper electrode 30 via the matcher 66. The high-frequency power supply 62 constitutes an example of a plasma generation part.

[0036] The bias power supply 64 is a power supply that generates 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 within the range of 400 kHz to 13.56 MHz. When the electrical bias is used together with the high-frequency power HF, it is applied to the substrate support 14 to draw ions into the substrate W. In one example, the electrical bias is applied to the lower electrode 18. 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. Incidentally, the electrical bias may be applied to a bias electrode provided in the electrostatic chuck 20.

[0037] In one embodiment, the electrical bias may be 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 high-frequency bias power for drawing 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 matcher 68 and an electrode plate 16. The matcher 68 has a circuit for matching the impedance on the load side (lower electrode 18 side) of the bias power supply 64 to the output impedance of the bias power supply 64.

[0038] Note that plasma may be generated using only the high-frequency power LF, that is, using only a single high-frequency power, without using the high-frequency power HF. In this case, the frequency of the high-frequency power LF may be a frequency greater than 13.56 MHz, for example, 40 MHz. Also, in this case, the plasma processing apparatus 1 may not include the high-frequency power supply 62 and the matcher 66. In this case, the bias power supply 64 constitutes an example of a plasma generation unit.

[0039] In one embodiment, the electrical bias may be a pulsed voltage (pulse voltage) (see FIG. 6). In this case, the bias power supply may be a DC power supply. The bias power supply may be configured such that the power supply itself supplies a pulse voltage, or may be configured to include a device that pulses the voltage on the downstream side of the bias power supply. In one example, the pulse voltage is applied to the substrate support 14 (lower electrode 18 or bias electrode 118) so that a negative potential is generated on the substrate W. The pulse voltage may be a rectangular wave, a triangular wave, an impulse, or may have other waveforms.

[0040] The period of the pulse voltage is defined by a second frequency. The period of the pulse voltage includes two periods. The pulse voltage in one of the two periods is a voltage of negative polarity. The level (i.e., absolute value) of the voltage in one of the two periods is higher than the level (i.e., absolute value) of the voltage in the other of the two periods. The voltage in the other period may be either of negative polarity or positive polarity. The level of the negative-polarity 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 an electrode plate 16. Note that the bias power supply 64 may be connected to a bias electrode 118 provided in the electrostatic chuck 20 instead of the lower electrode 18 (see FIG. 2).

[0041] In one embodiment, the bias power supply 64 may apply a continuous wave of electrical bias to the lower electrode 18. That is, the bias power supply 64 may continuously apply an electrical bias to the lower electrode 18.

[0042] In another embodiment, the bias power supply 64 may apply a pulse wave of electrical bias to the lower electrode 18. The pulse wave of electrical bias can be applied to the lower electrode 18 periodically. The period of the pulse wave of electrical bias 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 another example, the third frequency may be 5 Hz or more and 100 kHz or less.

[0043] The period of the pulse wave of the electric bias includes two periods, namely the H period and the L period (see Fig. 5). 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 and 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 the supply and the supply stop of the electric bias to the lower electrode 18. Here, when the electric bias is the 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 the 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 DC voltage, the level of the electric bias is the effective value of the absolute value of the negative DC voltage. The duty ratio of the pulse wave of the electric bias, that is, the ratio occupied by 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.

[0044] In one embodiment, the high-frequency power supply 62 may supply a continuous wave of the high-frequency power HF. That is, the high-frequency power supply 62 may continuously supply the high-frequency power HF.

[0045] In another embodiment, the high-frequency power supply 62 may supply a pulsed wave of high-frequency power HF. The pulsed wave of high-frequency power HF may be supplied periodically. The period of the pulsed 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 pulsed wave of high-frequency power HF includes two periods, namely, an H period and an L period. The power level of high-frequency power HF in the H period is higher than the power level of high-frequency power HF in the L period of the two periods. The power level of high-frequency power HF in the L period may be greater than zero or may be zero.

[0046] Note that the period of the pulsed wave of high-frequency power HF may be synchronized with the period of the pulsed wave of the electrical bias. The H period in the period of the pulsed wave of high-frequency power HF may be synchronized with the H period in the period of the pulsed wave of the electrical bias. Alternatively, the H period in the period of the pulsed wave of high-frequency power HF may not be synchronized with the H period in the period of the pulsed wave of the electrical bias. The duration of the H period in the period of the pulsed wave of high-frequency power HF may be the same as or different from the duration of the H period in the period of the pulsed wave of the electrical bias.

[0047] When plasma processing is performed in the plasma processing apparatus 1, gas is supplied from the gas supply unit to the internal space 10s. Further, 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 electrical bias. The generated high-frequency electric field generates plasma from the gas in the internal space 10s.

[0048] The plasma processing apparatus 1 may further include a control unit 80. The control unit 80 can be a computer including a processor, a storage unit such as a memory, an input device, a display device, a signal input / output interface, etc. The control unit 80 controls each part of the plasma processing apparatus 1. In the control unit 80, an operator can perform input operations of commands and the like for managing the plasma processing apparatus 1 using the input device. Also, in the control unit 80, the operating status of the plasma processing apparatus 1 can be visualized and displayed by the display device. Further, a control program and recipe data are stored in the storage unit. The control program is executed by the processor 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.

[0049] Note that the plasma formed in the plasma processing space may be, in addition to capacitively coupled plasma (CCP), inductively coupled plasma (ICP), ECR plasma (Electron-Cyclotron-resonance plasma), helicon wave plasma (HWP), or surface wave plasma (SWP), etc. Also, various types of plasma generation units including an AC (Alternating Current) plasma generation unit and a DC (Direct Current) plasma generation unit may be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Accordingly, the AC signal includes RF (Radio Frequency) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 200 kHz to 150 MHz.

[0050] FIG. 2 is a partially enlarged view of another example of the substrate support 14 included in the plasma processing apparatus 1. The substrate support 14 includes an electrode plate 16, a lower electrode 18, and an electrostatic chuck 20. The upper surface of the electrostatic chuck 20 has a substrate support surface 111a which is a central region for supporting the substrate W, and an annular region 111b for supporting the edge ring 25. The annular region 111b surrounds the substrate support surface 111a. The substrate W is disposed on the substrate support surface 111a, and the edge ring 25 is disposed on the annular region 111b so as to surround the substrate W on the substrate support surface 111a. The electrostatic chuck 20 is disposed on the lower electrode 18. The upper surface of the electrostatic chuck 20 has a substrate support surface for supporting the substrate W.

[0051] The electrostatic chuck 20 includes a chuck electrode 120 and a bias electrode 118 therein. The chuck electrode 120 has an electrode 120a provided between the substrate support surface 111a and the lower electrode 18. The electrode 120a may be a planar electrode corresponding to the shape of the substrate support surface 111a. Further, the chuck electrode 120 may have electrodes 120b and 120c provided between the edge ring 25 and the lower electrode 18. The electrodes 120b and 120c may be annular electrodes corresponding to the shape of the ring assembly 112. The electrode 120c is provided outside the electrode 120b. Note that the electrodes 120b and 120c may constitute a bipolar electrostatic chuck. Also, the electrodes 120a, 120b, and 120c may be integrally formed. The DC power supply 20p may be configured to apply different DC voltages to the electrodes 120a, 120b, and 120c, respectively, or may be configured to apply the same DC voltage.

[0052] The bias electrode 118 has an electrode 118a provided between the electrode 120a (or the substrate support surface 111a) and the lower electrode 18. The electrode 118a may be an electrode on a plane corresponding to the shape of the substrate support surface 111a and / or the electrode 120a. Further, the bias electrode 118 may have an electrode 118b provided between the edge ring 25 and the lower electrode 18. Although not shown, the substrate support 14 may include a temperature control module configured to adjust at least one of the electrostatic chuck 114, the ring assembly 112, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. Further, the substrate support 14 may include a heat transfer gas supply unit configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111a and / or between the edge ring 25 and the annular region 111b.

[0053] <An example of the substrate W> FIG. 3 is a diagram showing an example of a cross-sectional structure of the substrate W. The substrate W is an example of a substrate to which the present processing method can be applied. The substrate W has a silicon-containing film SF which is an example of a film to be etched in the present processing method. The substrate W may have an underlayer film UF and a mask film MK. As shown in FIG. 3, the substrate W may be formed by laminating the underlayer film UF, the silicon-containing film SF, and the mask film MK in this order.

[0054] The underlayer film UF may be an organic film, a dielectric film, a metal film, a semiconductor film, etc. formed on a silicon wafer. Further, the underlayer film UF may be a silicon wafer. Further, the underlayer film UF may be configured by laminating a plurality of films.

[0055] 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 having other film types as long as it is a film containing silicon. Also, the silicon-containing film SF may include a silicon film (e.g., a polycrystalline silicon film). Further, the silicon-containing film SF may include at least one of a silicon nitride film, a polycrystalline silicon film, a carbon-containing silicon film, and a low dielectric constant film. The carbon-containing silicon 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. Also, the silicon-containing film SF may include two or more different silicon-containing films. The two or more silicon-containing films may include a silicon oxide film and a silicon nitride film. The silicon-containing film SF may be, for example, a multilayer film including one or more silicon oxide films and one or more silicon nitride films alternately laminated. The silicon-containing film SF may be a multilayer film including a plurality of alternately laminated silicon oxide films and a plurality of silicon nitride films. Alternatively, the two or more silicon-containing films may include a silicon oxide film and a silicon film. The silicon-containing film SF may be, for example, a multilayer film including one or more silicon oxide films and one or more silicon films alternately laminated. The silicon-containing film SF may be a multilayer film including a plurality of alternately laminated silicon oxide films and a plurality of polycrystalline silicon films. Alternatively, the two or more silicon-containing films may include a silicon oxide film, a silicon nitride film, and a silicon film.

[0056] The mask film MK is provided on the silicon-containing film SF. The mask film MK is formed from a material having an etching rate lower than that of the silicon-containing film SF in step ST2. The mask film MK can be formed from an organic material. That is, the mask film MK may contain carbon. The mask film MK can be formed, for example, from an amorphous carbon film, a photoresist film, or a spin-on carbon film (SOC film). Alternatively, the mask film MK may be formed from a silicon-containing film such as a silicon-containing antireflection film. Alternatively, the mask film MK may be a metal-containing mask formed from a metal-containing material such as titanium nitride, tungsten, or tungsten carbide.

[0057] In one example, the substrate W may have a stacked film in which a silicon oxide film and a silicon nitride film are stacked on the underlying film UF as the silicon-containing film SF. Also, in one example, the substrate W may have a polycrystalline silicon film, silicon boride, or tungsten carbide as the mask film MK on the silicon nitride film. Also, the mask film MK may be a multilayer resist containing a polycrystalline silicon film, silicon boride, or tungsten carbide. The multilayer resist may have a mask including a hard mask on the polycrystalline silicon film in one example. The hard mask may have a silicon oxide film (TEOS film) in one example. The silicon nitride film included in the stacked film may be etched using the hard mask as a mask, and the silicon oxide film included in the stacked film may be etched using the polycrystalline silicon film as a mask.

[0058] The mask film MK is patterned to define at least one opening OP on the silicon-containing film SF. That is, the mask film MK has a pattern for etching the silicon-containing film SF in step ST2. Based on the shape of the opening OP defined by the pattern of the mask film MK, recesses such as holes or trenches are formed in the silicon-containing film SF. The aspect ratio of the recess formed in the silicon-containing film SF in step ST2 may be 20 or more, and may be 30 or more, 40 or more, or 50 or more. Note that the mask film MK may have a line and space pattern.

[0059] FIG. 4 is a flowchart showing an etching method (hereinafter also referred to as "this processing method") according to one exemplary embodiment. This processing method is executed on a substrate W using, for example, the plasma processing apparatus 1 shown in FIGS. 1 and 2.

[0060] FIG. 5 is a timing chart showing an example of high-frequency power HF and an electrical bias. FIG. 5 is an example in which both the high-frequency power HF and the electrical bias use pulse waves. That is, as an example, the high-frequency power HF is a pulse wave having an electrical pulse during the H period. Also, the electrical bias is a pulse wave having an electrical pulse during the H period. In FIG. 5, the horizontal axis represents time. In FIG. 5, the vertical axis represents the power level of the high-frequency power HF (for example, the effective value of the power of the high-frequency power HF) and the voltage level of the electrical bias (for example, the effective value of the absolute value of the voltage of the electrical bias). "L1" of the high-frequency power HF indicates that the high-frequency power HF is not supplied or is lower than the power level indicated by "H1". "L2" of the electrical bias indicates that the electrical bias is not supplied or is lower than the voltage level indicated by "H2".

[0061] FIG. 6 is a timing chart showing an example of a pulse voltage that constitutes an electric pulse of an electric bias (pulse wave). In FIG. 6, the horizontal axis represents time. In FIG. 6, the vertical axis represents the voltage value of the pulse voltage that constitutes the electric pulse. In the present embodiment, the voltage of the electric bias during the H period (that is, the pulse voltage that constitutes the electric bias) is a negative voltage. Note that the magnitudes of the power level of the high-frequency power HF and the voltage level of the electric bias in FIG. 5 do not indicate the relative relationship between the two, and may be arbitrarily set. FIG. 5 shows, as an example, that the period of the pulse wave of the high-frequency power HF is synchronized with the period of the pulse wave of the electric bias, and the time lengths of the H period and the L period of the pulse wave of the high-frequency power HF are the same as the time lengths of the H period and the L period of the pulse wave of the electric bias. In an example, the time lengths of the H period and the L period of the pulse wave of the high-frequency power HF and the time lengths of the H period and the L period of the pulse wave of the electric bias may be offset. In an example, the pulse wave of the high-frequency power HF may be in antiphase with the pulse wave of the electric bias.

[0062] Hereinafter, an example of executing the present processing method shown in FIG. 4 on the substrate W shown in FIG. 3 will be described with reference to each drawing. In the following example, the control unit 80 shown in FIG. 1 controls each part of the plasma processing apparatus 1 to execute the present processing method.

[0063] (Step ST1: Preparation of substrate) In step ST1, the substrate W is prepared in the internal space 10s of the chamber 10. Inside the internal space 10s, the substrate W is placed on the substrate support surface 111a of the substrate support 14 and held by the electrostatic chuck 114. At least a part of the process for forming each configuration of the substrate W may be performed inside the internal space 10s. Further, after all or a part of each configuration of the substrate W is formed by a device or chamber outside the plasma processing apparatus 1, the substrate W may be carried into the internal space 10s and placed on the substrate support surface 111a.

[0064] (Step ST2: Execution of etching) In step ST2, the silicon-containing film SF on the substrate W is etched. Step ST2 includes a step of supplying a processing gas (step ST21), a step of supplying high-frequency power (step ST22), and a step of applying an electrical bias. In step ST2, the silicon-containing film SF is etched by chemical species (ions, radicals, etc.) in the plasma generated from the processing gas. As an example, the chemical species is a chemical species of hydrogen fluoride (HF species). Note that the order in which steps ST21 to ST23 are executed is not limited to this order. Also, steps ST21 to ST23 may be executed simultaneously or in parallel.

[0065] In step ST21, the processing gas is supplied into chamber 10. The processing gas is a gas used to etch the film to be etched formed on the substrate W. The type of the processing gas may be appropriately selected based on the material of the film to be etched, the material of the mask film, the material of the underlying film, the pattern of the mask film, the etching depth, etc.

[0066] The processing gas used in step ST21 includes a gas species that generates HF species. The processing gas may include HF gas (hydrogen fluoride gas) as an example of the gas species that generates HF species. In another example, the gas species that generates HF species is H 2 and C s H t F u (s and u are positive integers, t is an integer of 0 or more), or C x H y F z (x, y, and z are positive integers). Also, in addition to the gas that generates HF species, the processing gas may include a gas containing fluorine or other halogen elements. The processing gas may include at least one halogen-containing molecule. The processing gas may include at least one of fluorocarbons or hydrofluorocarbons as at least one halogen-containing molecule. The fluorocarbon is, for example, CF 4 、C 3 F 8 、C 4 F 6 、or C 4 F 8is at least one of. The hydrofluorocarbon is, for example, CH 2 F 2 、CHF 3 、or CH 3 F is at least one of. The hydrofluorocarbon may contain two or more carbons. Also, the hydrofluorocarbon may contain three carbons, or four carbons. The hydrofluorocarbon is, for example, C 2 HF 5 、C 2 H 2 F 4 、C 2 H 3 F 3 、C 2 H 4 F 2 、C 3 HF 7 、C 3 H 2 F 2 、C 3 H 2 F 6 、C 3 H 2 F 4 、C 3 H 3 F 5 、C 4 H 5 F 5 、C 4 H 2 F 6 、C 5 H 2 F 10 and c-C 5 H 3 F 7 and may be at least one selected from the group consisting of. In one example, the carbon-containing gas is C 4 F 8 、C 3 H 2 F 4 and C 4 H 2 F 6It is at least one selected from the group consisting of. When the processing gas contains fluorocarbon and / or hydrofluorocarbon, fluorine species are generated in the plasma, and together with the hydrogen fluoride species, it promotes the etching of the silicon-containing film SF. Also, in the plasma, the carbon species generated from fluorocarbon and / or hydrofluorocarbon have the effect of protecting the mask film MK.

[0067] Also, the halogen-containing molecule may not contain carbon. The halogen-containing molecule is, for example, nitrogen trifluoride gas (NF 3 gas) or sulfur hexafluoride gas (SF 6 gas). Further, the processing gas may further contain a halogen-containing gas containing a halogen element other than fluorine. The halogen-containing gas is, for example, Cl 2 , SiH 2 Cl 2 , SiCl 4 , Si 2 Cl 6 , CHCl 3 , CCl 4 and BCl 3 It is at least one selected from the group consisting of. Also, in one example, the halogen-containing gas may be HBr, NF 3 .

[0068] The processing gas used in step ST21 may further contain at least one phosphorus-containing molecule. The phosphorus-containing molecule may be an oxide such as phosphorus pentoxide (P 4 O 10 ), phosphorus tetroxide octoxide (P 4 O 8 ), phosphorus tetroxide hexoxide (P 4 O 6 ). Phosphorus pentoxide is sometimes called phosphorus pentoxide (P 2 O 5 ). The phosphorus-containing molecule is phosphorus trifluoride (PF 3 ), phosphorus pentafluoride (PF 5 ), phosphorus trichloride (PCl 3 ), phosphorus pentachloride (PCl 5 ), phosphorus tribromide (PBr 3) Phosphorus pentabromide (PBr 5 ) Phosphorus iodide (PI 3 ) may be a halide (phosphorus halide) such as. That is, a molecule containing phosphorus may contain fluorine as a halogen element such as phosphorus fluoride. Alternatively, a molecule containing phosphorus may contain a halogen element other than fluorine as a halogen element. The phosphorus-containing molecule may be phosphoryl fluoride (POF 3 ), phosphoryl chloride (POCl 3 ), phosphoryl bromide (POBr 3 ). The phosphorus-containing molecule may be phosphine (PH 3 ), calcium phosphide (Ca 3 P 2 etc.), phosphoric acid (H 3 PO 4 ), sodium phosphate (Na 3 PO 4 ), hexafluorophosphoric acid (HPF 6 ) etc. The phosphorus-containing molecule may be fluorophosphines (H x PF y ). Here, the sum of x and y is 3 or 5. Examples of fluorophosphines include HPF 2 , H 2 PF 3 . The treatment gas may contain one or more of the above phosphorus-containing molecules as at least one phosphorus-containing molecule. For example, the treatment gas may contain at least one of PF 3 , PCl 3 , PF 5 , PCl 5 , POCl 3 , PH 3 , PBr 3 , or PBr 5 . When each phosphorus-containing molecule contained in the treatment gas is liquid or solid, each phosphorus-containing molecule may be vaporized by heating or the like and supplied into the chamber 10.

[0069] The treatment gas used in step ST21 may further contain carbon and hydrogen. The treatment gas may contain H as a molecule containing hydrogen 2, hydrocarbons (C x H y ), hydrofluorocarbons (C x H y F z ), or NH 3 may contain at least one of. The hydrocarbon is, for example, CH 4 or C 3 H 6 . Here, each of x and y is a positive integer. The processing gas may contain, as a carbon-containing molecule, a fluorocarbon or a hydrocarbon (e.g., CH 4 ). The processing gas may further contain oxygen. The processing gas may contain, for example, O 2 . Alternatively, the processing gas may not contain oxygen.

[0070] The processing gas used in step ST21 may include a phosphorus-containing gas, a fluorine-containing gas, and a hydrogen-containing gas containing at least one selected from the group consisting of hydrogen fluoride, hydrogen (H 2 ), ammonia, and hydrocarbons. The fluorine-containing gas may be a fluorocarbon and / or a hydrofluorocarbon. Also, the processing gas may be a phosphorus-containing gas, a fluorine-containing gas, a hydrofluorocarbon gas, and a halogen-containing gas containing a halogen element other than fluorine. The fluorine-containing gas is, for example, nitrogen trifluoride gas (NF 3 gas) or sulfur hexafluoride gas (SF 6 gas).

[0071] In step ST22, high-frequency power HF is supplied to the lower electrode 18. The high-frequency power HF is, for example, a pulse wave having a higher power level in the H period than in the L period and having electrical pulses in the H period, as shown in FIG. 5. Also, the high frequency constituting each pulse of the high-frequency power HF (pulse wave) has a frequency of, for example, 27 MHz to 100 MHz. When the high-frequency power HF is supplied to the lower electrode 18, for example, plasma is formed from the processing gas supplied into the chamber 10. In other embodiments, the high-frequency power HF may be supplied to the upper electrode (shower head) 30.

[0072] In process ST23, an electrical bias is supplied to bias electrode 118. The electrical bias has a voltage level higher than that in the L period in the H period and is a pulse wave having an electrical pulse in the H period, as shown in FIG. 5, for example. In one example, the frequency of the pulse wave is from 5 kHz to 100 kHz. Also, as shown in FIG. 6, the electrical pulse consists of a pulsed voltage (pulse voltage) that is repeated at a predetermined frequency. In one example, the predetermined frequency is 400 kHz. The pulse voltage may be a rectangular wave, a triangular wave, an impulse, or may have other waveforms. Note that in the present embodiment, the pulse voltage has a negative voltage in the H period. Also, the pulse voltage has a voltage higher than that in the H period in the L period. The voltage may be any of a positive voltage, a negative voltage, and a zero voltage.

[0073] In the H period, when high-frequency power HF is supplied to lower electrode 18 to generate plasma and an electrical bias is applied to bias electrode 118, positively charged active species in the plasma such as positive ions are drawn into substrate W disposed on substrate support surface 111a. Then, the active species collide with silicon-containing film SF through opening OP formed in mask film MK. As a result, the portion of silicon-containing film SF exposed at opening OP is etched, and a concave portion or an opening is formed in silicon-containing film SF.

[0074] Hereinafter, examples of the present processing method will be described.

[0075] <Example 1> In Example 1, a laminated film of a silicon oxide film and a silicon nitride film was etched for 10 minutes under the following conditions. Processing gas: HF, PF 3 , Cl 2 , HBr, NF 3 , CH 2 F 2 High-frequency power HF: 40 MHz, 3300 W Electrical bias: 400 kHz, 6000 V <Reference Example 1> As a reference example, instead of the electric bias in Example 1, a laminated film of a silicon oxide film and a silicon nitride film was etched for 10 minutes using high-frequency power LF. Other conditions were the same as in Example 1. Processing gas: HF, PF 3 , Cl 2 , HBr, NF 3 , CH 2 F 2 High-frequency power HF: 40 MHz, 3300 W High-frequency power LF: 400 kHz, 14000 W

[0076] FIG. 7 is a diagram schematically showing a cross section of a substrate W after etching a silicon-containing film SF (a laminated film of a silicon oxide film and a silicon nitride film) under the conditions of Example 1. Further, FIG. 8 is a diagram schematically showing a cross section of a substrate W after etching the silicon-containing film SF (a laminated film of a silicon oxide film and a silicon nitride film) of Reference Example 1. As shown in FIG. 7, in Example 1, the verticality of the concave portion RC was good (less bending), and a concave portion having a sufficient width could be obtained even at the lower end of the concave portion RC. On the other hand, as shown in FIG. 8, in Reference Example 1, the bending of the concave portion RC was larger than that in Example 1, and there was a concave portion RC that did not reach the underlying film UF. As a result, the width became narrow particularly near the lower end of the concave portion RC. The above results will be described with specific numerical values.

[0077] FIG. 9 is a diagram for explaining an example of a method for evaluating the cross-sectional shape of the concave portion RC. In FIG. 13, the center reference line CL is a line passing through the midpoint MP of the width of the concave portion RC on the lower surface of the mask film MK or the upper surface of the silicon-containing film SF. By measuring the deviation amount of the midpoint MP from the center reference line CL along the depth direction of the concave portion RC, the shape of the concave portion RC can be evaluated. For example, the bending and torsion of the concave portion RC formed in the silicon-containing film SF can be evaluated by the deviation amount.

[0078] FIG. 10 is a graph showing the degree of bending of the cross-sectional shape of the recess RC for Example 1 and Reference Example 1. Specifically, FIG. 10 shows the amount of deviation from the central reference line CL of the midpoint MP of the width of the recess RC obtained by etching the silicon-containing film SF (a laminated film of a silicon oxide film and a silicon nitride film) according to Example 1, and the amount of deviation from the central reference line CL of the midpoint MP of the width of the recess RC obtained by etching the silicon-containing film SF (a laminated film of a silicon oxide film and a silicon nitride film) according to Reference Example 1. In FIG. 10, the vertical axis represents the depth of the recess RC of the silicon-containing film SF. The horizontal axis represents the amount of deviation from the central reference line CL of the midpoint MP of the width of the recess RC. As shown in FIG. 10, in Example 1, the deviation of the midpoint MP with respect to the central reference line CL is at most about 5 nm. On the other hand, in Reference Example 1, particularly after a depth of about 3 μm, the midpoint MP deviated greatly from the central reference line CL, resulting in a large curvature of the cross-sectional shape of the recess RC.

[0079] FIG. 11 is a table showing the width (CD) of the recess RC for Example 1 and Reference Example 1. As shown in FIG. 11, in Example 1, the decrease in the width of the recess RC was suppressed in the vicinity of the underlayer film UF (i.e., near the lower end of the recess RC) as compared with the vicinity of the mask film MK (i.e., near the upper end of the recess RC). On the other hand, in Reference Example 1, the width of the recess RC decreased significantly in the vicinity of the underlayer film UF (i.e., near the lower end of the recess RC) as compared with the vicinity of the mask film MK (i.e., near the upper end of the recess RC).

[0080] <Example 2> In Example 2, a laminated film of a silicon oxide film and a silicon nitride film was etched for 10 minutes under the following conditions. Processing gas: HF, C 4 F 8 High-frequency power HF: 40 MHz, 5500 W Electrical bias: 400 kHz, 6000 V <Reference Example 2> Also, as a reference example, a laminated film of a silicon oxide film and a silicon nitride film was etched for 10 minutes using high-frequency power LF instead of the electrical bias in Example 2. Other conditions are the same as in Example 1. Processing gas: HF, C 4 F 8 High-frequency power HF: 40 MHz, 5500 W High-frequency power LF: 400 kHz, 10000 W

[0081] When the cross-section of the silicon-containing film SF (a laminated film of a silicon oxide film and a silicon nitride film) etched in Example 2 and Comparative Example 2 was observed, in Example 2, as in Example 1 (Fig. 7), the perpendicularity of the recess RC was good (less bending), and a recess having a sufficient width could be obtained even at the lower end of the recess RC. On the other hand, in Comparative Example 2, as in Comparative Example 1 (Figs. 8 and 10), as the depth of the recess RC increased, the bending of the recess RC increased. Further, in Comparative Example 1, there were recesses RC that did not reach the underlying film UF, and particularly, the width of the recess RC became narrow near the lower end of the recess RC.

[0082] The above embodiments have been described for the purpose of explanation, and various modifications can be made without departing from the scope and spirit of the present disclosure. For example, this processing method can be executed using a plasma processing apparatus using an arbitrary plasma source such as an inductively coupled plasma or a microwave plasma, in addition to the capacitively coupled plasma processing apparatus 1.

Explanation of reference numerals

[0083] 1... Plasma processing apparatus, 10... Chamber, 10s... Internal space, 12... Chamber body, 14... Substrate support, 16... Electrode plate, 18... Lower electrode, 20... Electrostatic chuck, 30... Upper electrode, 50... Exhaust device, 62... High-frequency power supply, 64... Bias power supply, 80... Control unit, SF... Silicon-containing film, MK... Mask film, OP... Opening, PF... Protective film, RC... Recess, UF... Underlying film, W... Substrate

Claims

1. 1. An etching method for etching a film to be etched through a mask in a plasma processing apparatus, comprising: The plasma processing apparatus includes: A chamber; a substrate support disposed within the chamber and configured to support a substrate; The etching method comprises: placing a substrate having a film to be etched and a mask defining at least one opening on the film to be etched on the substrate support; supplying a process gas containing hydrogen fluoride gas and CxHyFz (x and z are integers of 1 or more, and y is an integer of 0 or more) into the chamber; generating a plasma of the process gas in the chamber by radio frequency waves having a first frequency; applying a pulsed DC voltage to the substrate support periodically at a second frequency lower than the first frequency; An etching method comprising:

2. The etching method of claim 1 , wherein the process gas further comprises a phosphorus-containing gas.

3. The phosphorus-containing gas is PF 3 , PCl 3 , P.F. 5 , PCl 5 , POCl 3 , P.H. 3 , PBr 3 and PBr 5 The etching method according to claim 2 , comprising at least one selected from the group consisting of:

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

5. 5. The etching method according to claim 1, wherein the pulsed DC voltage is a negative voltage.

6. 1. An etching method for etching a film to be etched through a mask in a plasma processing apparatus, comprising: The plasma processing apparatus includes: A chamber; a substrate support disposed within the chamber and configured to support a substrate; The etching method comprises: placing a substrate having a film to be etched and a mask defining at least one opening on the film to be etched on the substrate support; supplying a process gas containing hydrogen fluoride gas and CxHyFz (x and z are integers of 1 or more, and y is an integer of 0 or more) into the chamber; generating a plasma containing hydrogen fluoride species from the process gas in the chamber by a radio frequency having a first frequency; applying a pulsed DC voltage to the substrate support periodically at a second frequency lower than the first frequency; An etching method comprising:

7. An etching apparatus for etching a film to be etched through a mask, comprising: The apparatus includes a chamber, a gas supply unit that supplies a process gas to the chamber, and a control unit; The control unit is placing a substrate having a film to be etched and a mask defining at least one opening on the film to be etched on a substrate support; supplying a process gas containing hydrogen fluoride gas and C x H y F z (x and z are integers of 1 or more, and y is an integer of 0 or more) into the chamber; generating a plasma of the process gas in the chamber by a radio frequency having a first frequency on the substrate support; periodically applying a pulsed DC voltage to the substrate support at a second frequency lower than the first frequency; Control is performed by the etching apparatus.

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