Plasma treatment method and plasma treatment system

Abstract

To achieve the formation of a fine pattern on a metal-containing film.SOLUTION: Provided is a plasma processing method implemented in a plasma processing apparatus having a chamber. The method includes: (a) a step for preparing, on a substrate support part in a chamber, a substrate having a film to be etched and a metal-containing film which is provided on the film to be etched, the metal-containing film having an exposed first region and an unexposed second region; (b) a step for reforming the metal-containing film by using a first plasma generated from a first treatment gas containing either a fluorine-containing gas or an oxygen-containing gas; and (c) a step for selectively removing the first region with respect to the second region in the reformed metal-containing film by using a second plasma generated from a second treatment gas.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Exemplary embodiments of the present invention relate to a plasma processing method and a plasma processing system.

Background Art

[0002] Patent Document 1 discloses a technique for trimming an inorganic film.

Prior Art Document

[0007] [Figure 1] This is a schematic diagram illustrating an exemplary plasma processing system. [Figure 2] This is a flowchart of the processing method. [Figure 3] This figure schematically shows an example of the cross-sectional structure of the substrate W provided in process ST1. [Figure 4] This figure schematically shows an example of the cross-sectional structure of the substrate W after processing in step ST2. [Figure 5] This figure schematically shows an example of the cross-sectional structure of the substrate W after processing in step ST3. [Figure 6] This figure schematically shows an example of the cross-sectional structure of the substrate W after processing in step ST4. [Modes for carrying out the invention]

[0008] The embodiments of this disclosure are described below.

[0009] In one exemplary embodiment, a plasma processing method is provided which is performed in a plasma processing apparatus having a chamber, and includes the steps of: (a) preparing a substrate having a film to be etched and a metal-containing film provided on the film to be etched on a substrate support in the chamber, wherein the metal-containing film has an exposed first region and an unexposed second region; (b) modifying the metal-containing film using a first plasma generated from a first processing gas containing either a fluorine-containing gas or an oxygen-containing gas; and (c) selectively removing the first region of the modified metal-containing film relative to the second region using a second plasma generated from a second processing gas.

[0010] In one exemplary embodiment, the modification in step (b) increases the etching resistance of the second plasma in the second region to be greater than the etching resistance of the second plasma in the first region.

[0011] In one exemplary embodiment, step (c) removes the first region so that the film to be etched is exposed.

[0012] In one exemplary embodiment, the metal-containing film contains tin or titanium.

[0013] In one exemplary embodiment, the metal-containing film contains an organic substance.

[0014] In one exemplary embodiment, the first processing gas contains at least one selected from the group consisting of fluorocarbon gas, hydrofluorocarbon gas, NF3 gas, and SF6 gas.

[0015] In one exemplary embodiment, the second processing gas contains a chlorine-containing gas.

[0016] In one exemplary embodiment, the chlorine-containing gas is BCl3 gas or Cl2 gas.

[0017] In one exemplary embodiment, the first processing gas contains at least one selected from the group consisting of O2 gas, CO gas, and CO2 gas.

[0018] In one exemplary embodiment, the first processing gas further contains a chlorine-containing gas.

[0019] In one exemplary embodiment, the chlorine-containing gas is at least one selected from the group consisting of Cl2 gas, BCl3 gas, and SiCl4 gas.

[0020] In one exemplary embodiment, the step (c) alternately repeats generating a second plasma using a gas containing a hydrogen-containing gas and a nitrogen-containing gas as a second processing gas and generating a second plasma using a gas containing a chlorine-containing gas as a second processing gas.

[0021] In one exemplary embodiment, the film to be etched is a Si-containing film or a carbon-containing film.

[0022] In one exemplary embodiment, after the step (c), it includes a step of etching the film to be etched using a metal-containing film as a mask.

[0023] In one exemplary embodiment, the steps (a) to (d) are performed in the same chamber.

[0024] In one exemplary embodiment, the metal-containing film includes a metal-containing photoresist film, the first region is the exposed region of the metal-containing photoresist film, and the second region is the unexposed region of the metal-containing photoresist.

[0025] In one exemplary embodiment, the first region is exposed by EUV.

[0026] Provided is a plasma processing system having a chamber, a substrate support provided in the chamber, and a control unit, wherein the control unit performs control to prepare a substrate having a film to be etched and a metal-containing film provided on the film to be etched on the substrate support, the metal-containing film having an exposed first region and an unexposed second region, control to modify the metal-containing film using a first plasma generated from a first processing gas containing either a fluorine-containing gas or an oxygen-containing gas, and control to selectively remove the first region of the modified metal-containing film with respect to the second region using a second plasma generated from a second processing gas.

[0027] Hereinafter, each embodiment of this disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are denoted by the same reference numeral, and redundant explanations are omitted. Unless otherwise specified, positional relationships such as top, bottom, left, and right will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and actual ratios are not limited to those shown.

[0028] <Example of a plasma processing system configuration> The following describes an example of a plasma processing system configuration. Figure 1 is a schematic diagram illustrating an exemplary plasma processing system.

[0029] The plasma processing system includes a plasma processing apparatus 1 using a microwave plasma source and a control unit 2. The plasma processing apparatus 1 includes a plasma processing chamber 10, a microwave plasma source 20, a gas supply unit 30, a bias power supply 40, and an exhaust system 50. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas introduction unit. The substrate support unit 11 is located inside the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by a ring-shaped support unit 101, the side walls 102 of the plasma processing chamber 10, an exhaust chamber 103, and the substrate support unit 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for discharging gas from the plasma processing space. The plasma processing chamber 10 is grounded.

[0030] The substrate support portion 11 includes a main body portion 111, a ring assembly 112, and a support member 113. The main body portion 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 in a plan view. The substrate W is placed on the central region 111a of the main body portion 111, and the ring assembly 112 is placed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also called the substrate support surface for supporting the substrate W, and the annular region 111b is also called the ring support surface for supporting the ring assembly 112.

[0031] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a bias electrode. The electrostatic chuck 1111 is placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b placed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may also have an annular region 111b. In this case, the ring assembly 112 may be placed on the annular electrostatic chuck or the annular insulating member, or on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode, which will be coupled to the RF (Radio Frequency) power supply 41 and / or DC (Direct Current) power supply 42 described later, may be placed within the ceramic member 1111a. In this case, at least one RF / DC electrode will function as a bias electrode. Note that the conductive member of the base 1110 and at least one RF / DC electrode may function as multiple bias electrodes. Also, the electrostatic electrode 1111b may function as a bias electrode. Therefore, the substrate support portion 11 includes at least one bias electrode.

[0032] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one covering ring. The edge rings are formed of a conductive or insulating material, and the covering rings are formed of an insulating material.

[0033] The support member 113 is a member that supports the main body 111. The support member 113 may be cylindrical in shape, extending upward from the center of the bottom of the exhaust chamber 103. The support member 113 is made of a ceramic material such as AlN.

[0034] The substrate support section 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, 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 1110a, or a combination thereof. A heat transfer fluid, such as brine or gas, flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are arranged within the ceramic member 1111a of the electrostatic chuck 1111. The substrate support section 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0035] The microwave plasma source 20 is supported by the support section 101. The microwave plasma source 20 includes a microwave transmission plate 21, a planar slot antenna 22, a slow-wave material 23, a cooling jacket 24, a coaxial waveguide 25, a mode converter 26, a waveguide 27, and a microwave generator 28.

[0036] The microwave-transmitting plate 21 is airtightly constructed via a sealing member at the support portion. Therefore, the plasma processing chamber 10 is kept airtight. The microwave-transmitting plate 21 may be a disc-shaped dielectric made of, for example, quartz or ceramics such as Al2O3.

[0037] The planar slot antenna 22 has multiple slots, is disc-shaped corresponding to the microwave-transmitting plate 21, and is configured to be in close contact with the microwave-transmitting plate 21. This planar slot antenna 22 may be locked to the upper end of the side wall 102 of the plasma processing chamber 10.

[0038] The planar slot antenna 22 may be, for example, a disc-shaped conductor. Alternatively, the planar slot antenna 22 may be made of, for example, a copper or aluminum plate with a silver or gold-plated surface, and may have multiple slots for radiating microwaves that penetrate through it in a predetermined pattern. The slot pattern may be set so that microwaves are radiated evenly to the substrate W. An example of a slot pattern is one in which multiple pairs of slots are arranged concentrically, with two slots arranged in a T-shape forming one pair. The length and spacing of the slots are determined according to the effective wavelength (λg) of the microwaves, and for example, the slots may be arranged so that the spacing between slots is λg / 4, λg / 2, or λg. The slots may also be circular, arc-shaped, or other shapes. Furthermore, the arrangement of the slots is not particularly limited, and in addition to concentric circles, they can also be arranged spirally or radially, for example. The planar slot antenna 22 may also be spaced apart from the microwave-transmitting plate 21.

[0039] The slow-wave material 23 is provided in close contact with the upper surface of the planar slot antenna 22. The slow-wave material 23 may be a dielectric material with a dielectric constant greater than that of a vacuum. The slow-wave material 23 may be formed from, for example, quartz, ceramics (Al2O3), polytetrafluoroethylene, polyimide, or other resins. The slow-wave material 23 has the function of adjusting the microwave phase by shortening the wavelength of microwaves compared to that in a vacuum. The slow-wave material 23 may also be positioned at a distance from the planar slot antenna 22.

[0040] The thicknesses of the microwave-transmitting plate 21 and the slow-wave material 23 are adjusted so that the equivalent circuit formed by the microwave-transmitting plate 21, the planar slot antenna 22, and the slow-wave material 23 satisfies the resonance conditions. By adjusting the thickness of the slow-wave material 23, the phase of the microwaves can be adjusted. By adjusting the thickness of the slow-wave material 23 so that the junction between the planar slot antenna 22 and the slow-wave material 23 becomes a standing wave "bulge," microwave reflection is minimized and the microwave radiation energy is maximized. Alternatively, the microwave-transmitting plate 21 and the slow-wave material 23 may be made of the same material to suppress interfacial reflection of microwaves.

[0041] The cooling jacket 24 is provided on the upper surface of the plasma processing chamber 10 so as to cover the planar slot antenna 22 and the slow-wave material 23. The cooling jacket 24 may be a heat conductor made of a metal material such as aluminum, stainless steel, or copper. The cooling jacket 24 is provided with a cooling water channel 24a. By flowing cooling water through the cooling water channel 24a, the microwave transmission plate 21, the planar slot antenna 22, and the slow-wave material 23 are cooled.

[0042] The coaxial waveguide 25 is inserted into the microwave transmission plate 21 from above an opening in the center of the cooling jacket 24. The coaxial waveguide 25 has a hollow rod-shaped inner conductor 25a and a cylindrical outer conductor 25b arranged concentrically. The upper end of the coaxial waveguide 25 is connected to the mode converter 26. The lower end of the inner conductor 25a is connected to the planar slot antenna 22. The lower end of the outer conductor 25b is connected to the slow-wave material 23.

[0043] The mode converter 26 is configured to be connected to a microwave generator 28 via a horizontally extending waveguide 27 with a rectangular cross-section. The mode converter 26 has the function of converting the vibration mode of microwaves.

[0044] Waveguide 27 is configured such that one end is connected to a mode converter 26 and the other end to a microwave generator 28. A matching circuit 27a is interposed in the waveguide 27.

[0045] The microwave generator 28 generates microwaves with a frequency of, for example, 2.45 GHz. The generated microwaves propagate through the waveguide 27, where the vibration mode is converted from TE mode to TEM mode by the mode converter 26, and then propagate towards the slow-wave material 23 via the coaxial waveguide 25. The microwaves spread radially outward within the slow-wave material 23 and are radiated from the slots of the planar slot antenna 22. The radiated microwaves pass through the microwave transmission plate 21, creating an electric field in the plasma processing space 10s directly below, and generating microwave plasma from the processing gas in the plasma processing space 10s. A tapered, annular recess 21a may be formed on the lower surface of the microwave transmission plate 21, enabling efficient generation of microwave plasma.

[0046] In addition to 2.45 GHz, various other microwave frequencies may be used, such as 8.35 GHz, 1.98 GHz, 860 MHz, and 915 MHz. Furthermore, for example, the microwave power may be between 2000 and 5000 W, and the power density between 2.8 and 7.1 W / cm².

[0047] The gas supply unit 30 may include at least one gas source 31 and at least one flow controller 32. In one embodiment, the gas supply unit 30 is configured to supply at least one processing gas to the gas inlet from a corresponding gas source 31 via a corresponding flow controller 32. Each flow controller 32 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 30 may include one or more flow modulation devices that modulate or pulse the flow rate of at least one processing gas.

[0048] The gas introduction section is configured to introduce at least one processing gas from the gas supply section 30 into the plasma processing space 10s. In one embodiment, the gas introduction section includes a gas channel 33 formed inside the inner conductor 25a of the mode converter 26 and coaxial waveguide 25, and the gas supply port 34 at the tip of this gas channel opens into the plasma processing space 10s, for example, in the central part of the microwave transmission plate 21. The processing gas introduced from the gas supply section 30 to the gas introduction section passes through the gas channel 33 and is supplied into the plasma processing space 10s from the gas supply port 34. In addition to or instead of the gas channel 33, the gas introduction section may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 102.

[0049] The bias power supply 40 includes an RF power supply 41 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 41 is configured to supply an RF signal (RF power) to the bias electrode. This generates a bias potential on the substrate W by supplying at least one bias RF signal to the bias electrode, thereby attracting ions in the formed plasma to the substrate W.

[0050] In one embodiment, the RF power supply 41 includes an RF generation unit 41a. The RF generation unit 41a is configured to be coupled to at least one bias electrode via at least one impedance matching circuit and to generate a bias RF signal (bias RF power). In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the RF generation unit 41a may be configured to generate a plurality of bias RF signals having different frequencies. One or more generated bias RF signals are supplied to at least one bias electrode. In various embodiments, the bias RF signal may also be pulsed.

[0051] Furthermore, the bias power supply 40 may include a DC power supply 42 coupled to the plasma processing chamber 10. The DC power supply 42 includes a bias DC generation unit 42a. In one embodiment, the bias DC generation unit 42a is connected to at least one bias electrode and configured to generate a bias DC signal. The generated bias DC signal is applied to at least one bias electrode.

[0052] In various embodiments, the bias DC signal may be pulsed. In this case, a sequence of voltage pulses is applied to at least one bias electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or a combination thereof pulse waveform. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses from a DC signal is connected between the bias DC generation unit 42a and at least one bias electrode. Thus, the bias DC generation unit 42a and the waveform generation unit constitute a voltage pulse generation unit. The voltage pulses may have positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. Note that the bias DC generation unit 42a may be provided in addition to the RF power supply 41.

[0053] The exhaust system 50 may be connected to, for example, a gas outlet 51 provided in the exhaust chamber 103. The exhaust system 50 may also include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0054] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described herein. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is implemented, for example, by a computer 2a. The processing unit 2a1 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or it may be obtained via a medium when needed. The obtained program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The memory unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).

[0055] <An example of a plasma treatment method> Figure 2 is a flowchart of a plasma processing method (hereinafter also referred to as "this processing method") according to one exemplary embodiment. As shown in Figure 2, this processing method includes a step ST1 for preparing a substrate, a step ST2 for modifying a metal-containing film (hereinafter also referred to as "modification process"), and a step ST3 for developing a metal-containing film (hereinafter also referred to as "development process"). This processing method may further include a step ST4 for etching a film to be etched. The processing in each step may be performed using the plasma processing system shown in Figure 1. In the following, a case in which the control unit 2 controls each part of the plasma processing apparatus 1 to execute this processing method on the substrate W will be described as an example.

[0056] (Step ST1: Preparation of the substrate) In step ST1, the substrate W is prepared in the plasma processing chamber 10s of the plasma processing apparatus 1. The substrate W is placed in the central region 111a of the substrate support section 11. The substrate W is then held in the substrate support section 11 by an electrostatic chuck 1111.

[0057] After the substrate W is placed in the central region 111a of the substrate support section 11, the temperature of the substrate support section 11 may be adjusted to a set temperature by a temperature control module. The set temperature may be, for example, 60°C or lower (room temperature in one example). In one example, adjusting or maintaining the temperature of the substrate support section 11 includes adjusting or maintaining the temperature of the heat transfer fluid flowing through the channel 1110a to the set temperature or a temperature different from the set temperature. In another example, adjusting or maintaining the temperature of the substrate support section 11 includes controlling the pressure of the heat transfer gas (e.g., He) between the electrostatic chuck 1111 and the back surface of the substrate W. The timing at which the heat transfer fluid begins to flow through the channel 1110a may be before, after, or simultaneously with the placement of the substrate W on the substrate support section 11. Furthermore, in this processing method, the temperature of the substrate support section 11 may be adjusted to the set temperature before step ST1. That is, the substrate W may be prepared on the substrate support section 11 after the temperature of the substrate support section 11 has been adjusted to the set temperature. In subsequent steps of this processing method, the temperature of the substrate support section 11 is maintained at the set temperature adjusted in step ST1.

[0058] Figure 3 shows an example of the cross-sectional structure of the substrate W prepared in step ST1. The substrate W has an etching target film EF and a metal-containing film MF stacked on a base film UF in that order. The substrate W may be used in the manufacture of semiconductor devices. Semiconductor devices include, for example, semiconductor memory devices such as DRAM and 3D-NAND flash memory.

[0059] The underlayer film UF is, in some cases, a silicon wafer or a carbon-containing film, dielectric film, metal film, or semiconductor film formed on a silicon wafer. The underlayer film UF may be composed of multiple films stacked on top of each other.

[0060] The etchable film EF is a different film from the underlying film UF. The etchable film EF may be, for example, a carbon-containing film, a dielectric film, a semiconductor film, or a metal film. The etchable film EF may consist of a single film or multiple films stacked together. For example, the etchable film EF may consist of one or more films stacked together, such as a silicon-containing film, a carbon-containing film, a spin-on-glass (SOG) film, or a Si-containing anti-reflective film (SiARC).

[0061] The undercoat film UF and the etchable film EF constituting the substrate W may be formed by CVD, ALD, spin coating, or the like, respectively. The undercoat film UF and the etchable film EF may be flat films or films with irregularities.

[0062] The metal-containing film MF is formed on the upper surface of the film EF to be etched. The metal-containing film MF is a film containing metal and has an exposed first region MF1 and an unexposed second region MF2.

[0063] The metal-containing film MF is a "negative" film. That is, the etching resistance to the plasma used in the development process is higher in the exposed first region MF1 than in the unexposed second region MF2. For example, when the metal-containing film MF is exposed to the second plasma used in the development process of step ST3, the unexposed second region MF2 is removed, and the exposed first region MF1 remains.

[0064] The metal-containing film MF may be a film containing tin or titanium. In one example, the metal-containing film may contain tin oxide. The metal-containing film MF may also contain organic matter. The metal-containing film MF may have different constituent components and / or their proportions in the first region MF1 and the second region MF2. In one example, the film constituting the first region MF1 may contain oxygen, carbon, and tin. In another example, the film constituting the second region MF2 may contain carbon and tin. The film constituting the first region MF1 and / or the second region MF2 may further contain silicon.

[0065] The metal-containing film MF may be formed by lithography. For example, first, a photoresist film containing metal is formed on the film EF to be etched. Next, light (e.g., an EUV excimer laser) is selectively irradiated onto the photoresist film through an exposure mask. This forms a metal-containing film MF having an exposed first region MF1 and an unexposed second region MF2. The first region MF1 corresponds to an opening provided in the exposure mask. The second region MF2 corresponds to a pattern provided in the exposure mask.

[0066] At least a portion of the process for forming each component of the substrate W may be carried out within the plasma processing space 10s. Alternatively, all or part of the components of the substrate W may be formed in an external apparatus or chamber outside the substrate processing apparatus 1, and then the substrate W may be provided into the plasma processing space 10s.

[0067] (Step ST2: Modification of metal-containing film) In step ST2, the metal-containing film MF is modified. First, a first processing gas is supplied from the gas supply unit 30 into the plasma processing chamber 10s. The first processing gas contains either a fluorine-containing gas or an oxygen-containing gas. Next, microwaves are emitted from the microwave plasma source 20 into the plasma processing chamber 10s. This generates a first plasma containing active species of fluorine or oxygen from the first processing gas. The metal-containing film MF is modified by exposure to the first plasma. The modification may include fluorination or oxidation of the metal-containing film MF. The modification may include a change in the composition and / or ratio of at least some of the metal-containing components of the metal-containing film MF. The modification may include hardening of part or all of the metal-containing film MF, or hardening of part of the metal-containing film MF more than other parts.

[0068] The first processing gas may contain a fluorine-containing gas. The fluorine-containing gas may, in one example, be at least one gas selected from the group consisting of fluorocarbon gas, hydrofluorocarbon gas, NF3 gas, and SF6 gas. In one example, the fluorocarbon gas may be at least one gas selected from the group consisting of CF4 gas, C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas, and C5F8 gas. In one example, the hydrofluorocarbon gas may be CHF3 gas, CH2F2 gas, CH3F gas, C2HF5 gas, C2H2F4 gas, C2H3F3 gas, C2H4F2 gas, C3HF7 gas, C3H2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, C5H2F 10 It may be at least one selected from the group consisting of gas and C5H3F7 gas.

[0069] The first treatment gas may contain an oxygen-containing gas instead of a fluorine-containing gas. The oxygen-containing gas may, in one example, be at least one gas selected from the group consisting of O2 gas, CO gas, and CO2 gas. If the first treatment gas contains an oxygen-containing gas, the first treatment gas may further contain a chlorine-containing gas. The chlorine-containing gas may, in one example, be at least one gas selected from the group consisting of HCl gas, Cl2 gas, BCl3 gas, and SiCl4 gas.

[0070] The first processing gas may further contain an inert gas such as a noble gas or N2 gas.

[0071] Figure 4 shows an example of the cross-sectional structure of the substrate W after processing in step ST2. In Figure 4, the modified metal-containing film MF is shown as metal-containing film MFa (MF1a, MF2a).

[0072] If the first processing gas contains a fluorine-containing gas, the metal-containing film MFa may be fluorinated by the active species of fluorine in the first plasma. That is, the first region MF1a and the second region MF2a after the modification treatment may have a higher fluorine content than the first region MF1 and the second region MF2 before the modification treatment. Consequently, the content ratio of other components (e.g., oxygen, carbon, or tin) that were present before the modification treatment may decrease. The surface of the first region MF1a after the modification treatment may be harder than the surface of the second region MF2a.

[0073] If the first processing gas contains an oxygen-containing gas, the metal-containing film MFa may be oxidized by the active oxygen species in the first plasma. The oxygen content of the first region MF1a and the second region MF2a after the modification treatment may be higher than that of the first region MF1 and the second region MF2 before the modification treatment. Consequently, the content ratio of other components (e.g., carbon or tin) that were present before the modification treatment may decrease. The surface of the first region MF1a after the modification treatment may be harder than the surface of the second region MF2a.

[0074] As described above, the metal-containing film MF before modification is a "negative" film. That is, the etching resistance to the plasma used in the development process is higher in the first region MF1 than in the second region MF2. In contrast, the metal-containing film MFa after modification becomes a "positive" film. That is, the etching resistance is higher in the second region MF2a than in the first region MF1a. As a result, for example, when the modified metal-containing film MFa is exposed to the second plasma used in the development process of step ST3, the first region MF1a is selectively etched and removed from the second region MF2a.

[0075] (Step ST3: Development of metal-containing film) In step ST3, the metal-containing film MFa is developed. First, a second processing gas is supplied from the gas supply unit 30 into the plasma processing chamber 10s. Next, microwaves are emitted from the microwave plasma source 20 into the plasma processing chamber 10s. This generates a second plasma from the second processing gas. At this time, a bias signal may be supplied to the lower electrode of the substrate support unit 11 to generate a bias potential between the second plasma and the substrate W. Active species such as ions and radicals in the second plasma are attracted to the substrate W, and the development process of the metal-containing film MFa proceeds due to these active species.

[0076] The second process gas may be selected in correspondence with the first process gas. If the first process gas contains a fluorine-containing gas, the second process gas will contain a chlorine-containing gas. The chlorine-containing gas may be, for example, BCl3 gas or Cl2 gas.

[0077] If the first process gas contains oxygen gas, the second process gas may contain hydrogen-containing gas (e.g., H2 gas), nitrogen-containing gas (e.g., N2 gas), and chlorine-containing gas (e.g., Cl2 gas). These gases do not have to be supplied simultaneously. For example, hydrogen-containing gas and nitrogen-containing gas may be supplied alternately as the second process gas, and chlorine-containing gas may be supplied alternately. That is, the process of supplying hydrogen-containing gas and nitrogen-containing gas as the second process gas to generate a second plasma and the process of supplying chlorine-containing gas as the second process gas to generate a second plasma may be repeated alternately.

[0078] Figure 5 shows an example of the cross-sectional structure of the substrate W after processing in step ST3. As described above, the etching resistance of the second region MF2a to the second plasma used in the development process is higher than that of the first region MF1a. Therefore, as shown in Figure 5, the first region MF1a is selectively etched and removed from the second region MF2a by the development process. This forms an opening OP in the metal-containing film MFa.

[0079] An opening OP is defined by the side surface of the second region MF2a. The opening OP is a space on the etched film EF enclosed by this side surface. In a plan view of the substrate W, the opening OP has a shape corresponding to the first region MF1a (and consequently, a shape corresponding to the opening of the exposure mask used to expose the metal-containing film MF). This shape may be, for example, a circle, an ellipse, a rectangle, a line, or a combination of one or more of these. Multiple openings OP may be formed in the metal-containing film MFa. Each of the multiple openings OP may have a hole shape and form an array pattern arranged at regular intervals. Alternatively, each of the multiple openings OP may have a line shape and form a line-and-space pattern arranged at regular intervals.

[0080] (Step ST4: Etching of the film to be etched) In step ST4, the etchable film EF is etched. First, a third processing gas is supplied from the gas supply unit 30 into the plasma processing chamber 10s. The third processing gas may be selected so that the etchable film EF is etched with a sufficient selectivity ratio compared to the metal-containing film MFa. Next, microwaves are emitted from the microwave plasma source 20 into the plasma processing chamber 10s. This generates a third plasma from the third processing gas. At this time, a bias signal may be supplied to the lower electrode of the substrate support unit 11 to generate a bias potential between the third plasma and the substrate W. Active species such as ions and radicals in the third plasma are attracted to the substrate W, and the etchable film EF is etched by these active species.

[0081] Figure 6 shows an example of the cross-sectional structure of the substrate W after processing in step ST4. In step ST4, the metal-containing film MFa functions as a mask, and the film EF to be etched is etched. As shown in Figure 6, step ST4 forms a recess RC in the film EF to be etched based on the shape of the opening OP of the metal-containing film MFa.

[0082] According to this processing method, a "negative" metal-containing film MF can be converted into a "positive" film through modification, allowing a pattern consisting of a second region MF2a that is not exposed to light to be formed on the metal-containing film MF through development. As a result, this processing method makes it possible to form fine patterns (e.g., fine hole array patterns) on the metal-containing film MF that are difficult to achieve with conventional "negative" photoresist films.

[0083] <Examples> Next, examples of this processing method will be described. This disclosure is not limited in any way by the following examples.

[0084] (Example 1) In Example 1, the processing method was applied to a substrate W using a plasma processing apparatus 1. The metal-containing film MF on the substrate W was formed by exposing a tin-containing photoresist film with EUV light. The first processing gas used in the modification process of step ST2 contained CF4 gas. The second processing gas used in the development process of step ST3 contained BCl3 gas and Cl2 gas.

[0085] (Reference example 1) In Reference Example 1, the same metal-containing film MF as in Example 1 was subjected to development under the same conditions as in step ST3 of Example 1, without performing the modification treatment in step ST2.

[0086] Table 1 shows the etching rates of the metal-containing film MF in Example 1 and Reference Example 1 during the development process. "ER1" is the etching rate of the first exposed region. "ER2" is the etching rate of the second unexposed region.

[0087] [Table 1]

[0088] As shown in Table 1, in Example 1, the etching rate of the first region during the development process was greater than that of the second region. In other words, the etching resistance of the second region to the plasma used in the development process was greater than that of the first region. In contrast, in Reference Example 1, the etching rate of the second region during the development process was greater than that of the first region. In other words, the etching resistance of the first region to the plasma used in the development process was greater than that of the second region.

[0089] (Example 2) In Example 2, the processing method was applied to the substrate W using the plasma processing apparatus 1. The metal-containing film MF on the substrate W was formed in the same manner as in Example 1. The first processing gas used in the modification process of step ST2 contained Cl2 gas and O2 gas. In the development process of step ST3, N2 gas, H2 gas, and Cl2 gas were supplied alternately as the second processing gas.

[0090] (Reference example 2) In Reference Example 2, the same metal-containing film MF as in Example 2 was developed under the same conditions as in step ST3 of Example 2, without performing the modification treatment in step ST2.

[0091] Table 2 shows the etching rates of the metal-containing film MF in Example 2 and Reference Example 2 during the development process. "ER1" is the etching rate of the first exposed region. "ER2" is the etching rate of the second unexposed region.

[0092] [Table 2]

[0093] As shown in Table 2, in Example 2, the etching rate of the first region during the development process was greater than that of the second region. In other words, the etching resistance of the second region to the plasma used in the development process was greater than that of the first region. In contrast, in Reference Example 2, the etching rate of the second region during the development process was greater than that of the first region. In other words, the etching resistance of the first region to the plasma used in the development process was greater than that of the second region.

[0094] This processing method can be modified in various ways without departing from the scope and spirit of this disclosure. For example, this processing method may be performed using a substrate processing apparatus that uses any plasma source other than the plasma processing apparatus 1 using a microwave plasma source, such as an inductively coupled plasma processing apparatus or a capacitively coupled plasma processing apparatus.

[0095] Embodiments of this disclosure further include the following embodiments:

[0096] (Note 1) A plasma processing method performed in a plasma processing apparatus having a chamber, (a) A step of preparing a substrate having a film to be etched and a metal-containing film provided on the film to be etched on a substrate support portion in a chamber, wherein the metal-containing film has an exposed first region and an unexposed second region, (b) A step of modifying the metal-containing film using a first plasma generated from a first treatment gas containing either a fluorine-containing gas or an oxygen-containing gas, (c) A step of selectively removing the first region of the modified metal-containing film relative to the second region using a second plasma generated from the second processing gas, A plasma treatment method, including the following.

[0097] (Note 2) The plasma treatment method according to Appendix 1, wherein the modification in step (b) above results in the etching resistance of the second region to the second plasma being greater than the etching resistance of the first region to the second plasma.

[0098] (Note 3) The plasma treatment method according to Appendix 1 or Appendix 2, wherein step (c) removes the first region so that the film to be etched is exposed.

[0099] (Note 4) The plasma treatment method according to any one of Appendix 1 to Appendix 3, wherein the metal-containing film contains tin or titanium.

[0100] (Note 5) The plasma treatment method described in Appendix 4, wherein the metal-containing film contains organic matter.

[0101] (Note 6) The plasma treatment method according to any one of the appendices 1 to 5, wherein the first treatment gas comprises at least one selected from the group consisting of fluorocarbon gas, hydrofluorocarbon gas, NF3 gas, and SF6 gas.

[0102] (Note 7) The plasma treatment method described in Appendix 6, wherein the second treatment gas includes a chlorine-containing gas.

[0103] (Note 8) The plasma treatment method according to Appendix 7, wherein the chlorine-containing gas is BCl3 gas or Cl2 gas.

[0104] (Note 9) The plasma treatment method according to any one of the appendices 1 to 5, wherein the first treatment gas includes at least one selected from the group consisting of O2 gas, CO gas, and CO2 gas.

[0105] (Note 10) The plasma treatment method described in Appendix 9, wherein the first treatment gas further contains a chlorine-containing gas.

[0106] (Note 11) The plasma treatment method according to Appendix 10, wherein the chlorine-containing gas is at least one selected from the group consisting of Cl2 gas, BCl3 gas, and SiCl4 gas.

[0107] (Note 12) The plasma treatment method according to any one of the appendices 9 to 11, wherein the step in (c) above is to generate the second plasma using a gas containing hydrogen and nitrogen as the second treatment gas, and to generate the second plasma using a gas containing chlorine as the second treatment gas, repeating these steps alternately.

[0108] (Note 13) The plasma treatment method according to any one of the appendices 1 to 12, wherein the film to be etched is a Si-containing film or a carbon-containing film.

[0109] (Note 14) A plasma treatment method according to any one of the appendices 1 to 13, further comprising the step of (d) etching the film to be etched using the metal-containing film as a mask, after the step of (c) above.

[0110] (Note 15) The plasma treatment method described in Appendix 14, wherein steps (a) to (d) above are performed in the same chamber.

[0111] (Note 16) The plasma processing method according to any one of the appendices 1 to 15, wherein the metal-containing film includes a metal-containing photoresist film, the first region is an exposed region of the metal-containing photoresist film, and the second region is an unexposed region of the metal-containing photoresist.

[0112] (Note 17) The plasma treatment method described in Appendix 16, wherein the first region is exposed by EUV.

[0113] (Note 18) A plasma processing system having a chamber, a substrate support section provided within the chamber, and a control section, The control unit, (a) A control for preparing a substrate on a substrate support portion, the substrate having a film to be etched and a metal-containing film provided on the film to be etched, wherein the metal-containing film has an exposed first region and an unexposed second region, (b) Control for modifying the metal-containing film using a first plasma generated from a first processing gas containing either a fluorine-containing gas or an oxygen-containing gas, (c) Control is performed which includes a control that uses a second plasma generated from a second processing gas to selectively remove the first region of the modified metal-containing film relative to the second region. Plasma processing system.

[0114] (Note 19) A device manufacturing method performed in a plasma processing apparatus having a chamber, (a) A step of preparing a substrate having a film to be etched and a metal-containing film provided on the film to be etched on a substrate support portion in a chamber, wherein the metal-containing film has an exposed first region and an unexposed second region, (b) A step of modifying the metal-containing film using a first plasma generated from a first treatment gas containing either a fluorine-containing gas or an oxygen-containing gas, (c) A step of selectively removing the first region of the modified metal-containing film relative to the second region using a second plasma generated from the second processing gas, A device manufacturing method comprising the following:

[0115] (Note 20) A computer for a plasma processing system comprising a chamber and a substrate support plasma generation unit provided within the chamber, (a) A control for preparing a substrate on a substrate support portion, the substrate having a film to be etched and a metal-containing film provided on the film to be etched, wherein the metal-containing film has an exposed first region and an unexposed second region, (b) Control for modifying the metal-containing film using a first plasma generated from a first processing gas containing either a fluorine-containing gas or an oxygen-containing gas, (c) Control to selectively remove the first region of the modified metal-containing film relative to the second region using a second plasma generated from the second processing gas, A program that executes control.

[0116] (Note 21) A storage medium containing the program described in Appendix 20. [Explanation of symbols]

[0117] 1...Plasma processing apparatus, 2...Control unit, 10...Plasma processing chamber, 10s...Plasma processing space, 11...Substrate support unit, 20...Microwave plasma source, 30...Gas supply unit, 40...Bias power supply, 50...Exhaust system, MF, MFa...Metal-containing film, EF...Etching target film, UF...Undercoat film, MF1, MF1a...First region, MF2, MF2a...Second region, OP...Opening, RC...Recess, W...Substrate

Claims

1. A plasma processing method performed in a plasma processing apparatus having a chamber, (a) A step of preparing a substrate having a film to be etched and a metal-containing film provided on the film to be etched on a substrate support portion in a chamber, wherein the metal-containing film has an exposed first region and an unexposed second region, (b) A step of modifying the metal-containing film using a first plasma generated from a first processing gas containing either a fluorine-containing gas or an oxygen-containing gas, (c) A step of selectively removing the first region of the modified metal-containing film relative to the second region using a second plasma generated from the second processing gas, A plasma treatment method, including the following.

2. The plasma treatment method according to claim 1, wherein the modification in step (b) above results in the etching resistance of the second region to the second plasma being greater than the etching resistance of the first region to the second plasma.

3. The plasma treatment method according to claim 2, wherein step (c) removes the first region so that the film to be etched is exposed.

4. The plasma treatment method according to any one of claims 1 to 3, wherein the metal-containing film comprises tin or titanium.

5. The plasma treatment method according to claim 4, wherein the metal-containing film contains an organic substance.

6. The first processing gas is fluorocarbon gas, hydrofluorocarbon gas, NF ３ Gas and SF ６ A plasma treatment method according to claim 1, comprising at least one selected from the group consisting of gases.

7. The plasma treatment method according to claim 6, wherein the second treatment gas includes a chlorine-containing gas.

8. The chlorine-containing gas is BCl ３ gas or Cl ２ The plasma treatment method according to claim 7, wherein the gas is used.

9. The first processing gas is O ２ Gas, CO gas and CO ２ The plasma treatment method according to claim 1, comprising at least one selected from the group consisting of gases.

10. The plasma treatment method according to claim 9, wherein the first treatment gas further comprises a chlorine-containing gas.

11. The chlorine-containing gas is Cl ２ gas, BCl ３ gas and SiCl ４ gas, and is at least one selected from the group consisting of the gases, and the plasma treatment method according to claim 10.

12. The plasma treatment method according to claim 9, wherein the step in (c) is to generate the second plasma using a gas containing hydrogen and nitrogen as the second treatment gas, and to generate the second plasma using a gas containing chlorine as the second treatment gas, and these steps are repeated alternately.

13. The plasma treatment method according to claim 1, wherein the film to be etched is a Si-containing film or a carbon-containing film.

14. The plasma treatment method according to claim 1, further comprising the step of (d) etching the film to be etched using the metal-containing film as a mask, after step (c).

15. The plasma treatment method according to claim 14, wherein steps (a) to (d) are performed in the same chamber.

16. The plasma processing method according to claim 1, wherein the metal-containing film includes a metal-containing photoresist film, the first region is an exposed region of the metal-containing photoresist film, and the second region is an unexposed region of the metal-containing photoresist film.

17. The plasma treatment method according to claim 16, wherein the first region is exposed by EUV.

18. A plasma processing system having a chamber, a substrate support section provided within the chamber, and a control section, The control unit, (a) A control for preparing a substrate on a substrate support portion, the substrate having a film to be etched and a metal-containing film provided on the film to be etched, wherein the metal-containing film has an exposed first region and an unexposed second region, (b) Control for modifying the metal-containing film using a first plasma generated from a first processing gas containing either a fluorine-containing gas or an oxygen-containing gas, (c) Control is performed which includes a control that uses a second plasma generated from a second processing gas to selectively remove the first region of the modified metal-containing film relative to the second region. Plasma processing system.

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