Etching method and plasma processing device

Abstract

Disclosed is an etching method which includes the following steps (a) to (d). In step (a), a substrate is prepared on a substrate support part in a chamber. The substrate includes a first region that contains silicon and nitrogen and a second region that contains silicon and oxygen. The first region has a recess that has an aspect ratio of 3 or more. The recess is filled with the second region. In step (b), a part of the second region is etched using a first plasma that is generated from a first processing gas which contains carbon and / or hydrogen, fluorine, and a metal. In step (c), the pressure in a space within the chamber is set to a pressure that is higher than the pressure in the step (b), and a metal-containing deposit is formed at least on the first region with use of the first plasma. In step (d), the second region is etched using a second plasma that is generated from a second processing gas which is different from the first processing gas.

Description

Etching method and plasma processing apparatus

[0001] TECHNICAL FIELD An embodiment of the present disclosure relates to an etching method and a plasma processing apparatus.

[0002] A plasma processing apparatus is used in etching a substrate. Patent Document 1 below discloses a method for etching an insulating film using plasma. In this method, etching is performed while forming a conductive layer on the surface of the insulating film during etching. ６ and C ４ F ８ The plasma generated from a gas mixture of

[0003] Japanese Patent Application Publication No. 9-50984

[0004] The present disclosure provides a technique that can prevent the first region from being removed when the second region is etched.

[0005] In one exemplary embodiment, an etching method is provided. The etching method includes the following steps (a), (b), (c), and (d). In step (a), a substrate is provided on a substrate support in a chamber. The substrate includes a first region containing silicon and nitrogen and a second region containing silicon and oxygen. The first region has a recess with an aspect ratio of 3 or greater. The recess is filled with the second region. In step (b), a portion of the second region is etched using a first plasma generated from a first process gas containing carbon and / or hydrogen, fluorine, and a metal. In step (c), a pressure in the space in the chamber is set higher than the pressure in the space in the chamber in step (b) after step (b), and a metal-containing deposit is formed on at least the first region using the first plasma. In step (d), after step (c), the second region is etched using a second plasma generated from a second process gas different from the first process gas.

[0006] According to the present disclosure, it is possible to prevent the first region from being removed when the second region is etched.

[0007] FIG. 2 is a diagram for explaining an example of the configuration of a plasma processing system. FIG. 2 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment. FIG. 3 is a diagram for explaining a plasma processing apparatus according to an exemplary embodiment. FIG. 4 is a flowchart of an etching method according to an exemplary embodiment. FIG. 5 is a partially enlarged cross-sectional view of an example substrate to which the method of FIG. 4 can be applied. FIG. 6 is a cross-sectional view showing a step of the etching method according to an exemplary embodiment. FIG. 7 is a cross-sectional view showing a step of the etching method according to an exemplary embodiment. FIG. 8 is a cross-sectional view showing a step of the etching method according to an exemplary embodiment. FIG. 9 is a cross-sectional view showing a step of the etching method according to an exemplary embodiment. FIG. 10 is a cross-sectional view showing a step of the etching method according to an exemplary embodiment. FIG. 11 is a cross-sectional view showing a step of the etching method according to an exemplary embodiment. FIG. 13 is a diagram for explaining a plasma processing apparatus according to another exemplary embodiment. FIG. 14 is a diagram showing a TEM image of a cross section of a substrate obtained by performing the etching method in the first, second, and third experiments.

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0009] FIG. 1 is a diagram illustrating an exemplary configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one precoat gas to the plasma processing space and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0010] The plasma generating unit 12 is configured to generate plasma from at least one precoat gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), or surface wave plasma (SWP). Various types of plasma generating units may be used, including alternating current (AC) plasma generating units and direct current (DC) plasma generating units. In one embodiment, the AC signal (AC power) used in the AC plasma generator has a frequency in the range of 100 kHz to 10 GHz. Therefore, AC signals include RF (Radio Frequency) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0011] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform 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 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. This program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0012] The following describes a configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0013] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one precoat gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0014] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a 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 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0015] 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 lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed 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. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF power supply 31 and / or a DC power supply 32 (described later) may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal (described later) is supplied to the at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple lower electrodes. Alternatively, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0016] 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 cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0017] The substrate support 11 may also include a temperature adjustment 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 adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the backside of the substrate W and the central region 111a.

[0018] The showerhead 13 is configured to introduce at least one precoat gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The precoat gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0019] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one pre-coat gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one pre-coat gas.

[0020] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates a plasma from at least one precoat gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0021] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0022] The second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0023] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0024] In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either 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 period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0025] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0026] A plasma processing apparatus according to an exemplary embodiment will be described below with reference to Figures 2 and 3. Figure 3 is a diagram showing an upper electrode and a shield member provided in the plasma processing apparatus shown in Figure 2.

[0027] 3, the sidewall 10a of the plasma processing chamber 10 has a substantially cylindrical shape. The sidewall 10a is connected to ground and has a ground potential. The upper end of the sidewall 10a is open.

[0028] The plasma processing apparatus 1 has a ceiling 14 above the plasma processing space 10s. The ceiling 14 is provided to close the opening of the plasma processing chamber 10. That is, the ceiling 14 covers and closes the opening at the upper end of the sidewall 10a. A portion of the ceiling 14 is exposed to the plasma processing space 10s.

[0029] The shower head 13, which constitutes part of the ceiling part 14, includes at least one upper electrode 13d. The upper electrode 13d is part of the ceiling part 14, is configured to be able to apply high-frequency power, and is provided above the substrate support part 11. The upper electrode 13d is electrically connected to, for example, a first RF generator 31a. The first RF generator 31a is an example of a high-frequency power source.

[0030] The upper electrode 13d includes a top plate 13e and a first support 13f. The top plate 13e has a substantially disk shape. The top plate 13e is in contact with the plasma processing space 10s. The top plate 13e is made of a conductive material such as silicon. The top plate 13e may be formed by forming a corrosion-resistant film on the surface of a conductive member such as aluminum. The corrosion-resistant film is made of a material such as aluminum oxide or yttrium oxide.

[0031] The first support 13f is provided on the top plate 13e. The first support 13f detachably supports the top plate 13e. The first support 13f is formed of, for example, aluminum. The first support 13f provides at least one gas diffusion chamber 13b therein. The first support 13f, together with the top plate 13e, provides at least one gas inlet 13c. The at least one gas inlet 13c extends downward from the at least one gas diffusion chamber 13b and penetrates the top plate 13e.

[0032] The ceiling portion 14 further includes a first insulating member 41. The first insulating member 41 is an example of an insulating portion. The first insulating member 41 is a part of the ceiling portion 14. The first insulating member 41 is formed of an insulator such as quartz. The first insulating member 41A includes a first insulating portion 46 and a second insulating portion 47. The first insulating portion 46 is provided between the upper electrode 13d and the plasma processing chamber 10. The first insulating portion 46 electrically separates the upper electrode 13d from the plasma processing chamber 10. The first insulating portion 46 is provided on the outer side (the sidewall 10a side) of the upper electrode 13d. The first insulating portion 46 has a substantially ring shape and extends circumferentially to surround the upper electrode 13d. The second insulating portion 47 will be described later.

[0033] The ceiling 14 further includes a shield member 42. The shield member 42 is another part of the ceiling 14 and is conductive. The shield member 42 is formed, for example, from a silicon-containing material. The shield member 42 extends from the periphery of the upper electrode 13d to the plasma processing chamber 10. The shield member 42 extends circumferentially to surround the periphery of the top plate 13e. The shield member 42 has, for example, a substantially annular shape. The shield member 42 is provided, for example, below the first insulating member 41. The shield member 42 extends so as not to expose the first insulating member 41 to the plasma processing space 10s. In the example shown in FIG. 3, the shield member 42 is provided below a portion of the first support 13f, the first insulating member 41, and a portion of a second support 43 (described later).

[0034] At least a portion of the portion exposed to the plasma processing space 10s (hereinafter also referred to as the exposed portion) is made of a conductor. The exposed portion includes, for example, at least a portion of the ceiling portion 14, at least a portion of the sidewall 10a, and at least a portion of the substrate support portion 11. For example, the exposed portion of the ceiling portion 14 is made of a conductor including the upper electrode 13d and the shield member 42. For example, the exposed portion of the ceiling portion 14 is made of only a conductor. In the example shown in FIG. 3, the exposed portion of the ceiling portion 14 is made of only the upper electrode 13d (or the top plate 13e) and the shield member 42.

[0035] The plasma processing chamber 10 may further include a second support 43. The second support 43 is provided outside the first insulating member 41 and above the shield member 42. A small gap is provided between the second support 43 and the shield member 42. The second support 43 is provided on the sidewall 10a of the plasma processing chamber 10. The second support 43 is electrically connected to the sidewall 10a of the plasma processing chamber 10. The potential of the second support 43 is set to ground potential. The first insulating member 41 is provided between the first support 13f of the upper electrode 13d and the second support 43. The second support 43 has a substantially ring shape and extends circumferentially to surround the first insulating member 41. The second support 43 is formed of a metal such as aluminum.

[0036] The second insulating portion 47 is provided outside the first insulating portion 46 and on the shield member 42. The second insulating portion 47 has, for example, a substantially ring shape and extends circumferentially to surround the first insulating portion 46. The second insulating portion 47 extends to protrude outward from the lower end of the first insulating portion 46. The second insulating portion 47 is interposed between the plasma processing chamber 10 and the shield member 42. In the example shown in FIG. 3 , the second insulating portion 47 is provided such that its lower surface is in contact with the outer upper surface of the shield member 42. The second insulating portion 47 is provided between the shield member 42 and the second support 43.

[0037] Thus, in the plasma processing apparatus 1, a first insulating member 41 having a first insulating portion 46 and a second insulating portion 47 is interposed between the upper electrode 13d and the plasma processing chamber 10, and between the plasma processing chamber 10 and the shield member 42.

[0038] The plasma processing apparatus 1 further includes at least one second insulating member 45. The at least one second insulating member 45 is provided below the shield member 42. The at least one second insulating member 45 is interposed between the plasma processing chamber 10 and the shield member 42. The shield member 42 is supported between the second insulating portion 47 and the at least one second insulating member 45.

[0039] 3 , the at least one second insulating member 45 includes a third support 45a and a sealing member 45b. The third support 45a is provided on the sidewall 10a. The third support 45a supports the shield member 42 from below. A portion of the inner surface of the third support 45a may be exposed to the plasma processing space 10s below the ceiling 14. The sealing member 45b is provided between the shield member 42 and the third support 45a. The sealing member 45b is arranged so as to contact an outer portion of the shield member 42 and an outer portion of the third support 45a. The sealing member 45b is, for example, an O-ring that separates a reduced-pressure environment including the plasma processing space 10s from an atmospheric pressure environment.

[0040] The upper electrode 13d and / or the shield member 42 are electrically connected to the second DC generator 32b. In the example shown in FIG. 3 , a DC connector 48 is provided within the second support 43. The DC connector 48 extends from the inside of the second support 43 through the second insulating portion 47 and connects to an outer portion of the shield member 42. The outer portion of the shield member 42 may be, for example, a radially outer portion of the shield member 42 that is not exposed to the plasma processing space 10s. The outer portion of the shield member 42 may be the peripheral portion of the shield member 42. The outer portion of the shield member 42 is supported by being sandwiched between the lower end of the DC connector 48 and at least one second insulating member 45. For example, the lower end of the DC connector 48 is provided directly above the sealing member 45b of at least one second insulating member 45 in the circumferential direction.

[0041] The second DC signal generated by the second DC generator 32b is applied to the upper electrode 13d and / or the shield member 42 via the DC connector 48. According to the plasma processing apparatus 1, even if the DC connector 48 is located outside the first insulating member 41, the DC connector 48 penetrates the second insulating portion 47 to connect to the shield member 42, thereby allowing the second DC signal to be appropriately applied to the shield member 42. By applying the second DC signal to the shield member 42, the second DC signal is applied to the upper electrode 13d via the shield member 42. The second DC signal, i.e., the bias signal, applied to the upper electrode 13d and / or the shield member 42 is a negative DC voltage or voltage pulse (negative voltage pulse). The voltage pulse is applied periodically at a frequency of, for example, 400 kHz. The absolute value of the voltage level of the DC voltage or voltage pulse, which is the second DC signal, may be less than 100 V or may be 100 V or greater and 1000 V or less. As a result, a negative DC voltage having an absolute value of less than 100 V or a negative DC voltage having an absolute value of 100 V or more and 1000 V or less is applied to the upper electrode 13 d and / or the shield member 42 .

[0042] In the plasma processing apparatus 1, the first RF generating unit 31a may generate a signal having a frequency of, for example, 100 MHz as a source RF signal and supply it to the upper electrode 13d. Furthermore, the second RF generating unit 31b may generate a signal having a frequency of, for example, 13 MHz as a bias RF signal and supply it to the lower electrode of the substrate support unit 11. Alternatively, the first DC generating unit 32a may supply a first DC signal to the lower electrode of the substrate support unit 11.

[0043] The current based on the source RF signal, i.e., the radio frequency power, supplied to the upper electrode 13d can flow through two paths: a first path that does not pass through the plasma, and a second path that passes through the plasma. In the first path, the current flows from the upper electrode 13d to the sidewall 10a via the shield member 42, the second insulating portion 47 of the first insulating member 41, and the second support 43. In the second path, the current flows from the upper electrode 13d to the sidewall 10a via the plasma in the plasma processing space 10s. The second insulating portion 47 of the first insulating member 41 reduces the electrostatic capacitance between the shield member 42 and the second support 43, thereby increasing the impedance of the first path. Therefore, the radio frequency power supplied to the upper electrode 13d is efficiently coupled to the plasma in the plasma processing space 10s. Furthermore, the radio frequency power supplied to the upper electrode 13d is more efficiently coupled to the plasma below the shield member 42.

[0044] The inner wall portion 10t on the inside of the side wall 10a exposed to the plasma processing space 10s is made of a conductor. The inner wall portion 10t is made of, for example, silicon. The inner wall portion 10t can serve as a counter electrode for the shield member 42. At least a portion of the current applied to the shield member 42 flows to the side wall 10a via the plasma in the plasma processing space 10s and the inner wall portion 10t. In this way, because the inner wall portion 10t is made of a silicon-containing material, it is not necessary to separately place another member (device) serving as a counter electrode in the plasma processing space 10s.

[0045] An etching method according to one exemplary embodiment will be described below with reference to Fig. 4. Fig. 4 is a flowchart of the etching method according to one exemplary embodiment. The etching method MT shown in Fig. 4 (hereinafter referred to as "method MT") can be performed by the plasma processing apparatus 1 according to the above embodiment. The method MT can be applied to a substrate W.

[0046] 5 is a partially enlarged cross-sectional view of an example substrate to which the method of FIG. 4 can be applied. As shown in FIG. 5, in one embodiment, the substrate W includes a first region R1 and a second region R2. The first region R1 may have at least one recess R1a. The first region R1 may have multiple recesses R1a. Each recess R1a may be a recess for forming a contact hole. The recess R1a is filled with a second region R2. The second region R2 may be provided to cover the first region R1.

[0047] The first region R1 includes silicon and nitrogen. The first region R1 is made of silicon nitride (SiN ｘ The first region R1 may include a silicon nitride (SiN). The first region R1 may be a region formed by, for example, CVD or the like, or may be a region obtained by nitriding silicon. ｘ The first portion may include a first portion including silicon carbide (SiC), and a second portion including silicon carbide (SiC). In this case, the first portion has the recess R1a.

[0048] The aspect ratio of the recess R1a may be, for example, 3 or more, 4 or more, 5 or more, or 10 or more. The aspect ratio of the recess R1a indicates the ratio of the depth of the recess R1a to the maximum width dimension of the recess R1a.

[0049] The second region R2 includes silicon and oxygen. The second region R2 includes silicon oxide (SiO ｘ The second region R2 may be a region formed by, for example, CVD or the like, or may be a region obtained by oxidizing silicon.

[0050] The substrate W may further include a third region R3. The third region R3 is provided on the second region R2. The third region R3 may include a metal, carbon, and nitrogen. Here, the metal includes tungsten. The third region R3 may have an opening OP3. The width of the opening OP3 may correspond to the width of the recess R1a.

[0051] The substrate W may include an underlying region UR and at least one raised region RA provided on the underlying region UR. The underlying region UR and the at least one raised region RA are covered by a first region R1. The underlying region UR may include silicon. A plurality of raised regions RA are located on the underlying region UR. Recesses R1a of the first region R1 are located between the plurality of raised regions RA. Each raised region RA may form a gate region of a transistor.

[0052] The substrate W may include a mask MK. The mask MK is provided on the third region R3. The mask MK may include metal or silicon. The mask MK may have an opening OPM. The opening OPM corresponds to the opening OP3 in the third region R3.

[0053] Method MT will be described below with reference to FIGS. 5 to 11, taking as an example a case where method MT is applied to a substrate W using the plasma processing apparatus 1 of the above embodiment. FIGS. 5 to 11 are cross-sectional views showing steps of an etching method according to one exemplary embodiment. When the plasma processing apparatus 1 is used, method MT can be performed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 with a controller 2. In method MT, a substrate W is processed on a substrate support 11 (substrate support) arranged in a plasma processing chamber 10, as shown in FIGS. 2 and 3.

[0054] 4, the method MT may include steps ST1, ST2, ST3, ST4, ST5, ST6, and ST7. Steps ST1 to ST7 may be performed in order. The method MT may not include at least one of steps ST2, ST4, ST6, ST7, and ST8. Step ST2 may be included in step ST1.

[0055] In step ST1, a substrate W shown in FIG. 5 is prepared. The substrate W is transferred into the plasma processing chamber 10 by a transfer device (not shown). The substrate W may be supported by a substrate support 11 in the plasma processing chamber 10. The substrate W may have the shape shown in FIG. 5 as a result of plasma etching, or may have the shape shown in FIG. 5 from the beginning when provided to the plasma processing chamber 10. In step ST1, the second region R2 may be provided so as to cover the first region R1. In step ST1, the upper surface of the second region R2 is exposed. That is, in step ST1, the upper surface of the silicon oxide is exposed.

[0056] 6, in step ST2, the control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to etch a part of the second region R2 using a first plasma PL1 generated from the first process gas, thereby exposing the first region R1. In step ST2, the shoulder portion SH of the recess R1a in the first region R1 can be etched to expose it.

[0057] In one example, the first process gas may include a carbon-containing gas and / or a hydrogen-containing gas and a metal-containing gas. Also, in one example, the first process gas may include at least one selected from the group consisting of a tungsten-containing gas, a molybdenum-containing gas, and a titanium-containing gas immediately before the first region R1 is exposed.

[0058] The metal-containing gas may include at least one selected from the group consisting of a tungsten-containing gas, a molybdenum-containing gas, and a titanium-containing gas. The tungsten-containing gas may include a tungsten halide gas. The tungsten halide gas may be tungsten hexafluoride (WF ６ ) gas, tungsten hexabromide (WBr ６ ) gas, tungsten hexachloride (WCl ６ ) Gas and WF ５ The tungsten-containing gas may include at least one of tungsten hexacarbonyl (W(CO) ６The molybdenum-containing gas may include a molybdenum halide gas. The molybdenum halide gas may include molybdenum hexafluoride (MoF ６ ) gas, and molybdenum hexachloride (MoCl ６ The titanium-containing gas may include at least one selected from the group consisting of titanium halide gas. The titanium halide gas may include titanium tetrachloride (TiCl ４ ), titanium tetrafluoride (TiF ４ ) and titanium tetrabromide (TiBr ４ ) may contain at least one selected from the group consisting of

[0059] The carbon-containing gas is CH ４ Gas, C ２ H ２ Gas, C ２ H ４ Gas, CH ３ F gas, CH ２ F ２ Gas, CHF ３ The gas may include at least one selected from the group consisting of a gas and a CO gas.

[0060] The hydrogen-containing gas is H ２ Gas, SiH ４ Gas and NH ３ The gas may include at least one selected from the group consisting of:

[0061] The first process gas may further include a noble gas, such as argon gas, helium gas, xenon gas, or neon gas. ２ ) gas.

[0062] The flow rate ratio of the metal-containing gas may be smaller than the flow rate ratio of at least one of the carbon-containing gas and the hydrogen-containing gas. The flow rate ratio of the noble gas may be larger than the flow rate ratio of at least one of the carbon-containing gas and the hydrogen-containing gas. In the present disclosure, the flow rate ratio of each gas is the ratio (volume %) of the flow rate of each gas to the total flow rate of the process gas.

[0063] In step ST2, the pressure in plasma processing chamber 10 may be 10 mTorr (1.3 Pa) or more, or may be less than 100 mTorr (13 Pa) or 50 mTorr (6.7 Pa) or less.

[0064] A mask MK is used in the etching. The etching in step ST2 may be performed as follows. First, the control unit 2 controls the exhaust system 40 to adjust the pressure in the plasma processing space 10s to 10 mTorr or more and less than 100 mTorr. By controlling the exhaust system 40, exhaust is performed and the pressure in the plasma processing space 10s is adjusted to 10 mTorr or more and less than 100 mTorr. The exhaust system 40 may adjust the pressure in the plasma processing space 10s to 50 mTorr or less.

[0065] Next, the control unit 2 controls the gas supply unit 20 to supply a first process gas into the plasma processing chamber 10. Next, the control unit 2 controls the plasma generation unit 12 to generate a first plasma PL1 from the process gas in the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to etch the second region R2 so that the first region R1 is exposed.

[0066] In step ST2, a source RF signal may be applied from the first RF generator 31a to the high-frequency electrode, which may be an upper electrode or a lower electrode.

[0067] In step ST2, a bias signal may be supplied to the lower electrode in the main body 111 of the substrate support part 11. In one example, when a bias signal is supplied to the substrate support part 11 in step ST2, a bias RF signal may be supplied from the second RF generation part 31b to the lower electrode in the main body 111 of the substrate support part 11.

[0068] In another example, when a bias signal is supplied to the substrate support 11 in step ST2, a sequence of voltage pulses may be supplied from the first DC generator 32a to the lower electrode in the main body 111 of the substrate support 11. In particular, bias power may not be applied immediately before or after the first region R1 is exposed. As a result, deposits are more likely to be formed, and etching of the shoulder portion SH in the recess R1a is suppressed.

[0069] 7 , in step ST3, the control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to form a metal-containing deposit DP on at least the first region R1 using a second plasma PL2 generated from the second process gas. The control unit 2 uses the second plasma PL2 to form the metal-containing deposit DP on the surface of the first region R1. The second plasma PL2 may also be used to form the metal-containing deposit DP on the surface of the second region R2. The surfaces of the first region R1 and the second region R2 include the side surfaces and the top surfaces.

[0070] When the first region R1 and the second region R2 are exposed to the second plasma PL2, the metal-containing deposit DP may be preferentially formed on the first region R1 relative to the second region R2. Here, "the metal-containing deposit DP may be preferentially formed on the first region R1 relative to the second region R2" means, for example, that the thickness of the metal-containing deposit DP on the first region R1 is greater than the thickness of the metal-containing deposit DP on the second region R2. More specifically, it means that the thickness of the metal-containing deposit DP on the second region R2 is 50% or less of the thickness of the metal-containing deposit DP on the first region R1. For example, the thickness of the metal-containing deposit DP on the shoulder portion SH of the first region R1 is greater than the thickness of the metal-containing deposit DP on the second region R2 located within the recess R1a of the first region R1.

[0071] The second process gas in step ST3 and the first process gas in step ST2 may be the same gas or different gases. In one example, the second process gas is the same gas as the first process gas and contains the same gas species as the first process gas. An example of the second process gas is the same as the example of the process gas in step ST2. In another example, the second process gas is a gas different from the first process gas and may contain a different ratio or type of metal-containing gas from the metal-containing gas contained in the first process gas.

[0072] The metal-containing deposit DP varies depending on the type of metal-containing gas contained in the second process gas. That is, the metal-containing deposit DP may be any of a tungsten-containing film, a molybdenum-containing film, and a titanium-containing film. The metal-containing deposit DP may contain carbon. The metal-containing deposit DP may be tungsten carbide (WC). ｘ After step ST3, the maximum thickness of the metal-containing deposit DP may be 5 nm or more.

[0073] In step ST3, the pressure in the plasma processing chamber 10 may be 100 mTorr (13 Pa) or higher. Alternatively, the pressure in the plasma processing chamber 10 may be 300 mTorr (40 Pa) or lower. In step ST3, the pressure is set to be higher than the pressure in the plasma processing space 10s in the plasma processing chamber 10 in step ST2. Therefore, the metal-containing deposit DP can be deposited on the shoulder portion SH of the first region R1 located deep below the top surface of the third region R3 and on the side surface of the first region R1 that forms the recess R1a.

[0074] The formation of the metal-containing deposit DP in step ST3 may be performed as follows: First, the control unit 2 controls the exhaust system 40 to adjust the pressure in the plasma processing space 10s to 100 mTorr or more and 300 mTorr or less. By controlling the exhaust system 40, gas is supplied or exhausted, and the pressure in the plasma processing space 10s is adjusted to 100 mTorr or more and 300 mTorr or less.

[0075] Next, the gas supply unit 20 supplies a second process gas into the plasma processing chamber 10. Next, the plasma generation unit 12 generates a second plasma PL2 from the second process gas in the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 so that a metal-containing deposit DP is formed at least on the first region R1. The control unit 2 may also control the gas supply unit 20 and the plasma generation unit 12 so that a metal-containing deposit DP is formed on the second region R2.

[0076] Without being bound by theory, the metal-containing deposit DP may be formed as follows. Here, an example will be described in which the second process gas contains a tungsten-containing gas as the metal-containing gas. When the second process gas contains carbon, activated species containing tungsten in the second plasma PL2 react with activated species containing carbon in the second plasma PL2 to form tungsten carbide (WC) on at least the surface of the first region R1. ｘ ) is deposited. Alternatively, when the second process gas contains hydrogen and the metal-containing deposit DP contains fluorine, the fluorine-containing active species in the metal-containing deposit DP are scavenged by the hydrogen-containing active species in the second plasma PL2. As a result, the metal-containing deposit DP derived from the tungsten-containing active species remaining in the second plasma PL2 is deposited on at least the surface of the first region R1. When the first process gas contains both carbon and hydrogen, the reaction between tungsten and carbon and the scavenging of fluorine by hydrogen proceed simultaneously.

[0077] In step ST3, a source RF signal may be applied from the first RF generating unit 31a to the radio-frequency electrode. The radio-frequency electrode may be an upper electrode or a lower electrode. In step ST3, a source RF signal having a power level of 100 W or more and 1000 W or less may be supplied. In step ST3, a source RF signal having a power level of 200 W or more and 800 W or less may be supplied. In step ST3, a source RF signal having a power level of 300 W or more and 500 W or less may be supplied. In step ST3, a source RF signal having a frequency of 27 MHz or more and 100 MHz or less may be supplied.

[0078] In step ST3, similarly to step ST2, a bias signal does not need to be supplied to the lower electrode in the main body 111 of the substrate support part 11, and a bias signal having a power level lower than that of the bias signal in ST5 described below may be supplied. In one example, when the control unit 2 supplies a bias signal to the substrate support part 11 in step ST3, a high-frequency bias signal having a power level of less than 100 W may be supplied from the second RF generation unit 31 b to the lower electrode in the main body 111 of the substrate support part 11.

[0079] In another example, when the control unit 2 supplies a bias signal to the substrate support 11 in step ST3, a sequence of voltage pulses having a voltage level of less than 100 V may be supplied from the first DC generator 32 a to the lower electrode in the main body 111 of the substrate support 11. The first DC signal applied to the substrate support 11 is a negative DC voltage or voltage pulses (negative voltage pulses). The voltage pulses are applied periodically at a frequency of, for example, 100 kHz to 800 kHz.

[0080] At or after step ST3, a counter electrode facing the substrate support 11 may be sputtered. The counter electrode includes silicon. A negative DC voltage may be applied to the counter electrode by the second DC generator 32b at the shield member 42. The absolute value of the DC voltage applied to the counter electrode may be 100 V or more or 1000 V or less. For example, noble gas ions in the second plasma PL2 collide with the counter electrode, thereby releasing silicon into the second plasma PL2. When sputtering is performed after step ST3, sputtering may be performed using plasma generated from a process gas containing a noble gas.

[0081] Next, in step ST4, as shown in FIG. 8 , the control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to remove the metal-containing deposit DP formed on the second region R2 using a fourth plasma generated from the fourth process gas. The metal-containing deposit DP is formed on the second region R2 embedded in the recess R1a of the first region R1. The metal-containing deposit DP is removed by etching with the fourth plasma or by sputtering using ions in the fourth plasma. In step ST4, the second region R2 within the recess R1a of the first region R1 (or directly above the recess R1a) can be etched to expose it.

[0082] In one example, the fourth process gas is N ２ The fourth process gas may include a gas and CO. In one example, the fourth process gas may also include a noble gas, such as argon gas, helium gas, xenon gas, or neon gas.

[0083] In step ST4, the etching of the metal-containing deposit DP may be performed as follows: First, the control unit 2 controls the gas supply unit 20 to supply a fourth process gas into the plasma processing chamber 10. Next, the control unit 2 controls the plasma generation unit 12 to generate a fourth plasma PL4 from the fourth process gas in the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to etch the metal-containing deposit DP formed on the second region R2 using the fourth plasma PL4.

[0084] In step ST4, a source RF signal may be applied from the first RF generating unit 31a to the radio-frequency electrode. The radio-frequency electrode may be an upper electrode or a lower electrode. In step ST3, a source RF signal having a power level of 100 W or more and 1000 W or less may be supplied. In step ST3, a source RF signal having a power level of 200 W or more and 800 W or less may be supplied. In step ST3, a source RF signal having a power level of 300 W or more and 500 W or less may be supplied. In step ST3, a source RF signal having a frequency of 27 MHz or more and 100 MHz or less may be supplied.

[0085] In step ST4, a bias signal may be supplied to the lower electrode in the main body 111 of the substrate support 11. In one example, when a bias signal is supplied to the substrate support 11 in step ST4, a bias RF signal may be supplied from the second RF generator 31b to the lower electrode in the main body 111 of the substrate support 11. In step ST4, a bias RF signal having a power level of less than 100 W may be supplied. In another example, when a bias signal is supplied to the substrate support 11 in step ST4, a sequence of voltage pulses may be supplied from the first DC generator 32a to the lower electrode in the main body 111 of the substrate support 11.

[0086] In step ST4, the control unit 2 may sputter the substrate W placed on the substrate support 11. When supplying a bias signal to the substrate support 11 in step ST4, a sequence of voltage pulses may be supplied from the first DC generator 32a to a lower electrode in the main body 111 of the substrate support 11. A sequence of voltage pulses having a voltage level of 100 V or more and 1000 V or less may be supplied from the first DC generator 32a to the lower electrode in the main body 111 of the substrate support 11.

[0087] Without being bound by theory, the metal-containing deposit DP can be sputtered as follows: For example, the metal-containing deposit DP formed on the second region R2 is reacted with CO using a fourth plasma PL4 generated from a fourth process gas, thereby making the metal-containing deposit DP brittle. ２ The gas may cause sputtering of the brittle metal-containing deposit DP.

[0088] 9 , in step ST5, the controller 2 controls the gas supply unit 20 and the plasma generating unit 12 to etch the second region R2 using a third plasma PL3 generated from a third process gas different from the first process gas and the second process gas. The etching may be performed as follows: First, the controller 2 controls the gas supply unit 20 to supply the third process gas into the plasma processing chamber 10. Next, the controller 2 controls the plasma generating unit 12 to generate the third plasma PL3 from the third process gas in the plasma processing chamber 10. The controller 2 controls the gas supply unit 20 and the plasma generating unit 12 to etch the second region R2 using the third plasma PL3.

[0089] The third process gas may be different from the first process gas and the second process gas. In one example, the third process gas includes a fluorine-containing gas. The second process gas may include a fluorine-containing gas. The fluorine-containing gas may include at least one selected from the group consisting of hydrogen fluoride gas, hydrofluorocarbon gas, and fluorocarbon gas. Fluorocarbon (C ｘ F ｙ ) gas is CF ４ Gas, C ３ F ６ Gas, C ３ F ８ Gas, C ４ F ８ Gas and C ４ F ６ The gas may include at least one of hydrofluorocarbons (C ｘ H ｙ F ｚ ) gas is CH ２ F ２ Gas, CHF ３ Gas and CH ３ At least one of F gas may be included.

[0090] The third process gas may contain a metal-containing gas. As a result, deposits are more likely to be formed, and etching of the shoulder portion SH of the recess R1a is suppressed. In another example, the third process gas may not contain a metal-containing gas. Examples of gases other than the fluorine-containing gas in the third process gas are the same as the examples of the second process gas in step ST2.

[0091] In step ST5, the first region R1 is covered with the metal-containing deposit DP and is therefore difficult to etch. The second region R2 is more easily etched than the first region R1 because the metal-containing deposit DP has been removed in step ST4. By etching the second region R2, a contact hole HL is formed, as shown in FIG. 9 . The contact hole HL corresponds to the recess R1a in the first region R1. In this way, step ST4 may be performed in a self-aligned contact (SAC) process.

[0092] In step ST5, as in step ST2, a bias signal having a power level greater than that of the bias signal in step ST3 may be supplied to the lower electrode in the main body 111 of the substrate support 11. The following description is an example of power used for a substrate W having a diameter of 300 mm. For example, when the control unit 2 supplies a bias signal to the substrate support 11 in step ST5, a bias RF signal having a power level of 10 W or more and 300 W or less may be supplied to the lower electrode from the second RF generation unit 31b as a high-frequency bias signal. A bias RF signal having a power level of 30 W or more and 200 W or less may be supplied to the lower electrode from the second RF generation unit 31b. A bias RF signal having a power level of 50 W or more and 100 W or less may be supplied to the lower electrode from the second RF generation unit 31b. A bias RF signal having a frequency of 100 kHz or more and 40.68 MHz or less may be supplied to the lower electrode from the second RF generation unit 31b as a high-frequency bias signal.

[0093] In another example, when the control unit 2 supplies a bias signal to the lower electrode in the main body 111 of the substrate support 11 in step ST5, a sequence of voltage pulses having a voltage level of 100 V to 1000 V may be supplied from the first DC generator 32a. The first DC signal applied to the substrate support 11 is a negative DC voltage or voltage pulse (negative voltage pulse). The voltage pulse is applied periodically at a frequency of, for example, 100 kHz to 800 kHz.

[0094] In step ST6, it is determined whether a sufficient amount of the metal-containing deposit DP remains. This determination may be made by the control unit 2. If it is determined that a sufficient amount of the metal-containing deposit DP remains, the process proceeds to step ST6. If it is determined that a sufficient amount of the metal-containing deposit DP remains, the process returns to step ST3. This determination may be made based on the etching time. For example, the relationship between the etching time in step ST5 and the amount of reduction of the metal-containing deposit DP is calculated in advance. Using this relationship, the amount of reduction of the metal-containing deposit DP is estimated from the remaining etching time required to form the contact hole HL. If the value obtained by subtracting the estimated amount of reduction of the metal-containing deposit DP from the initial amount of the metal-containing deposit DP is equal to or greater than a threshold, it is determined that a sufficient amount of the metal-containing deposit DP remains. Alternatively, the determination may be made based on reflected light obtained by irradiating the metal-containing deposit DP with light. For example, in step ST5, the reflected light obtained by irradiating the metal-containing deposit DP with light is measured. If the intensity of the reflected light at a wavelength corresponding to the metal-containing deposit DP is equal to or greater than a threshold, it is determined that a sufficient amount of the metal-containing deposit DP remains.

[0095] In step ST7, it is determined whether the etching stop condition of step ST5 is satisfied. This determination can be made by the control unit 2. If it is determined that the stop condition is satisfied, the process proceeds to step ST8. If it is determined that the stop condition is not satisfied, the process returns to step ST3. The stop condition includes, for example, removal of the second region R2 in the recess R1a as shown in FIG. 10 .

[0096] In step ST8, after step ST7, the control unit 2 performs control to remove the metal-containing deposit DP. After the second region R2 in the recess R1a is removed, the metal-containing deposit DP may remain on the first region R1. The metal-containing deposit DP may be removed by cleaning after step ST7. After step ST8 is completed, the method MT is terminated.

[0097] As described above, in the method MT, a cycle including at least step ST3 and step ST5 may be repeated two or more times. In the method MT, a cycle including step ST3, step ST4, and step ST5 may be repeated two or more times. FIG. 11 is a partially enlarged cross-sectional view of the substrate W after step ST3 is performed in the second or subsequent cycle before the stop condition is satisfied, when a cycle including step ST3, step ST4, and step ST5 is repeated two or more times. In step ST3, the second plasma PL2 is generated under high-pressure conditions, thereby generating metal-containing deposits DP with a small adhesion coefficient. Therefore, the metal-containing deposits DP can adhere not only to the shoulder portion SH of the first region R1 but also to the side surfaces of the first region R1 that form the recesses R1a at positions away from the shoulder portion SH of the first region R1 toward the underlying region UR. Note that Figure 10 is a partial cross-sectional view of a substrate W in a state in which a cycle including steps ST3, ST4, and ST5 has been repeated two or more times, and metal-containing deposits DP have adhered not only to the shoulder portion SH of the first region R1 but also to the side surfaces of the first region R1 that form the recess R1a.

[0098] According to the method MT, the first region R1 can be prevented from being etched during etching of the second region R2 in step ST5. In step ST3, the control unit 2 can form a metal-containing deposit DP having excellent etching resistance at least on the surface of the first region R1. Furthermore, because the plasma (second plasma PL2) is generated under higher pressure conditions in step ST3 than in step ST2, a metal-containing deposit DP with a lower sticking coefficient is generated. Therefore, the metal-containing deposit DP can adhere not only to the shoulder portion SH of the first region R1 but also to the side surface of the first region R1 that forms the recess R1a located away from the shoulder portion SH of the first region R1 toward the underlying region UR. This prevents the shoulder portion SH of the first region R1 and the side surface that forms the recess R1a of the first region R1 from being etched during etching of the second region R2 in step ST5, even when the first region R1 has a recess R1a with an aspect ratio of 3 or greater. Furthermore, even if the etching time of the second region R2 in step ST5 is extended, the shoulder portion SH of the first region R1 is protected by the metal-containing deposit DP, and is therefore prevented from being removed by etching.

[0099] Without being bound by theory, the reason for this is thought to be as follows. In step ST3, when the first process gas contains hydrogen, activated species containing hydrogen in the first plasma PL1 function as fluorine scavengers. As a result, the fluorine concentration in the metal-containing deposit DP is reduced, thereby improving the etching resistance of the metal-containing deposit DP in step ST5. In step ST3, when the first process gas contains carbon, carbon-tungsten bonds are formed in the metal-containing deposit DP. As a result, the etching resistance of the metal-containing deposit DP in step ST5 is improved.

[0100] Sputtering the counter electrode facing the substrate support 11 at or after step ST3 further improves the etching resistance of the metal-containing deposit DP. Without being bound by theory, the reason for this is believed to be as follows: When the counter electrode is sputtered, silicon is released from the counter electrode. Silicon functions as a fluorine scavenger. As a result, the fluorine concentration in the metal-containing deposit DP is reduced, thereby improving the etching resistance of the metal-containing deposit DP in step ST5.

[0101] In step ST3, bias power may not be applied to the lower electrode in the main body 111 of the substrate support 11, or the bias power applied may be less than 100 W. In this case, when the metal-containing deposit DP is formed, etching of the first region R1 by the first plasma PL1 can be suppressed.

[0102] In step ST3, the control unit 2 may form the metal-containing deposit DP on the second region R2 so that the thickness of the metal-containing deposit DP is smaller than that of the metal-containing deposit DP formed on the first region R1. In this case, the first region R1 can be protected by a thicker layer than the second region R2, which is to be removed by etching. Furthermore, the process of removing the second region R2 in step ST4 can be easily completed.

[0103] In step ST3, the control unit 2 may control the substrate support unit 11 to not supply a bias signal or to supply a bias signal having a power level lower than that in step ST5. In this case, not supplying a bias signal can prevent the shoulder portion SH of the first region R1 from being scraped.

[0104] In step ST4, the control unit 2 may use a fourth plasma PL4 generated from the fourth process gas to sputter the metal-containing deposit DP formed on the second region R2 embedded in the recess R1a of the first region R1. In this case, even if the metal-containing deposit DP is formed not only on the surface of the first region R1 but also on the second region R2 in step ST3, the fourth plasma PL4 can sputter the metal-containing deposit DP on the second region R2. That is, by removing the metal-containing deposit DP so that the second region R2 is exposed to the plasma processing space 10s while suppressing removal of the metal-containing deposit DP on the surface of the first region R1, the second region R2 can be more easily etched in step ST5.

[0105] In step ST5, the control unit 2 may perform control to supply a bias signal to the substrate support unit 11. In this case, in step ST5, the bias signal can be supplied so that the second region R2 located in the recess R1a of the first region R1 can be appropriately etched.

[0106] In the method MT, a cycle including at least steps ST3 and ST5 is repeated two or more times. In this case, even if a recess R1a having an aspect ratio of 3 or more is formed in the first region R1, the second region R2 can be etched in step ST5 while preventing the first region R1 from being etched.

[0107] After step ST7, in step ST8, the control unit 2 may perform control to remove the metal-containing deposit DP. In this case, the control unit 2 can generate a substrate W from which the metal-containing deposit DP has been removed and in which the shoulder portion SH of the first region R1 is exposed.

[0108] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0109] For example, in step ST3, the control unit 2 may control the gas supply unit 20 and the plasma generation unit 12 to form a carbon-containing deposit on the first region R1 before forming the metal-containing deposit DP. In this case, the metal-containing deposit DP is formed on the carbon-containing deposit. The carbon-containing deposit is formed on the first region R1 using plasma generated from a processing gas containing carbon. When the first region R1 and the second region R2 are exposed to plasma, the carbon-containing deposit may be preferentially formed on the first region R1 compared to the second region R2. The processing gas containing carbon may include a carbon-containing gas. The carbon-containing gas may be CH ４ Gas, C ２ H ２ Gas, C ２ H ４ Gas, CH ３ F gas, CH ２ F ２ Gas, CHF ３ The process gas may include at least one selected from the group consisting of a nitrogen gas and a CO gas. The process gas may include a noble gas such as argon gas, helium gas, xenon gas, or neon gas.

[0110] Hereinafter, a plasma processing apparatus according to another exemplary embodiment, which can be used in a plasma processing apparatus capable of performing the method MT, will be described with reference to FIG. 12 . FIG. 12 is a diagram for explaining a plasma processing apparatus according to the other exemplary embodiment. The plasma processing apparatus 1A according to the exemplary embodiment shown in FIG. 12 differs from the plasma processing apparatus 1 in that it includes a first insulating member 41A and a third insulating member 44. That is, the plasma processing apparatus 1A differs in that it does not include the second insulating portion 47 of the first insulating member 41.

[0111] The ceiling portion 14 includes a first insulating member 41A. The first insulating member 41A is a part of the ceiling portion 14. The first insulating member 41A has a generally ring shape and extends in the circumferential direction so as to surround the upper electrode 13d. The first insulating member 41A is made of an insulator such as quartz.

[0112] The plasma processing apparatus 1A includes at least one third insulating member 44. The at least one third insulating member 44 is provided outside the first insulating member 41A and on the shield member 42. The at least one third insulating member 44 is interposed between the plasma processing chamber 10 and the shield member 42. In the example shown in FIG. 12 , the at least one third insulating member 44 is provided so that its lower surface contacts the outer upper surface of the shield member 42. The at least one third insulating member 44 is provided between the shield member 42 and the second support 43. The at least one third insulating member 44 is, for example, a plate-shaped member having a substantially annular shape. The at least one third insulating member 44 is formed from an insulator such as insulating ceramics, quartz, or metal oxide.

[0113] The shielding member 42 is supported between at least one third insulating member 44 and at least one second insulating member 45. The DC connection portion 48 passes from inside the second support 43 through at least one third insulating member 44 and connects to a portion outside the shielding member 42.

[0114] It should be noted that the plasma processing apparatus of another exemplary embodiment capable of performing the method MT may not include the shield member 42 .

[0115] Various experiments performed to evaluate Method MT are described below, but the experiments described below are not intended to limit the present disclosure.

[0116] (First Experiment) In the first experiment, silicon nitride (SiN ｘ a first region R1 including a silicon oxide (SiO ｘ A substrate W including a first region R1 and a second region R2 including a first region R1 and a second region R2 was prepared. The upper surfaces of the first region R1 and the second region R2 were exposed. Thereafter, steps ST3, ST4, and ST5 were performed on the substrate W using the plasma processing apparatus 1.

[0117] In step ST3, a second plasma PL2 was generated from a second process gas, and the first region R1 and the second region R2 were exposed to the second plasma PL2. The second process gas was methane (CH ４ ) gas and nitrogen (N ２) gas and hydrogen (H ２ ) gas. No negative DC voltage was applied to the counter electrode facing the substrate support 11. Step ST3 was performed for 190 seconds after the second plasma PL2 was generated. The pressure in the plasma processing chamber 10 in step ST3 was 300 mTorr. In step ST3, a source RF signal having a power level of 500 W was supplied.

[0118] In step ST4, a fourth plasma PL4 was generated from a fourth process gas, and the metal-containing deposit DP on the second region R2 was sputtered. The fourth process gas was nitrogen (N ２ ) gas and carbon monoxide (CO) gas.

[0119] In step ST5, a third plasma PL3 was generated from a third process gas to etch the second region R2. ４ F ６ Gas, argon gas and oxygen (O ２ ) gas mixture.

[0120] (Second Experiment) In the second experiment, methane (CH ４ ) gas and nitrogen (N ２ ) gas and hydrogen (H ２ ) gas and tungsten hexafluoride (WF ６ A mixed gas of the second plasma PL2 and the second processing gas PL3 was used. Step ST3 was performed for 100 seconds after the second plasma PL2 was generated. Except for the second processing gas and processing time in step ST3, the same method as in the first experiment was performed.

[0121] (Third Experiment) In the third experiment, methane (CH ４ ) gas, argon (Ar) gas, and hydrogen (H ２ ) gas and tungsten hexafluoride (WF ６ A mixed gas of the second plasma PL2 and the second processing gas PL3 was used. Step ST3 was performed for 60 seconds after the second plasma PL2 was generated. Except for the second processing gas and processing time in step ST3, the same method as in the first experiment was performed.

[0122] (Experimental Results) TEM images of the cross section of the substrate W on which the etching method was performed in the first to third experiments were observed. FIG. 13 shows TEM images of the cross section of the substrate obtained by performing the etching method in the first to third experiments. (a) of FIG. 13 shows the cross section of the substrate W after step ST3 and before step ST4 in the first experiment. (b) of FIG. 13 shows the cross section of the substrate W after step ST3 and before step ST4 in the second experiment. (c) of FIG. 13 shows the cross section of the substrate W after step ST3 and before step ST4 in the third experiment. (b) and (c) of FIG. 13 confirmed that deposits formed on the third region R3 (the dark gray portion in the figure). The results of TEM-EDX confirmed that the portions corresponding to the deposits in (b) and (c) of FIG. 13 contained tungsten. That is, it was confirmed that the deposits DP2 and DP3 in Figures 13(b) and 13(c) were metal-containing deposits DP (tungsten-containing deposits). In contrast, in Figure 13(a), no blackish-gray (dark gray) portion was confirmed within the deposit formed on the third region R3. The results of TEM-EDX confirmed that the portion corresponding to the deposit in Figure 13(a) did not contain metal. That is, it was confirmed that the deposit DP1 in Figure 13(a) was not a metal-containing deposit DP.

[0123] 13A to 13C, the total thickness of the deposits was measured. The total thickness of the deposits in the first experiment was 27.0 nm. The total thickness of the deposits in the second experiment was 32.6 nm. The total thickness of the deposits in the third experiment was 23.2 nm. Comparing the first experiment with the second experiment and the third experiment revealed that even when the processing time in step ST3 is short, deposits can be efficiently deposited when the second processing gas contains a metal-containing gas.

[0124] 14A and 14B are TEM images of cross sections of substrates obtained by performing the etching method in Experiments 1 to 3. Fig. 14A shows the cross section of the substrate W after step ST5 in Experiment 1. Fig. 14B shows the cross section of the substrate W after step ST5 in Experiment 2. Fig. 14C shows the cross section of the substrate W after step ST5 in Experiment 3. As is clear from these figures, the thickness of the metal-containing deposits in the shoulder portion SH of each first region R1 in Experiments 2 and 3 was greater than the thickness of the deposits in the shoulder portion SH of the first region R1 in Experiment 1.

[0125] The thicknesses of the deposits DP1 to DP3 were measured in each of (a) to (c) of Figure 14, and the difference from the thicknesses of the deposits DP1 to DP3 measured in (a) to (c) of Figure 13 was calculated to calculate the reduction amounts of the deposits DP1 to DP3 due to step ST4. The reduction amount of the deposit DP1 in the first experiment was 27.0 nm. The reduction amount of the deposit DP2 in the second experiment was 16.7 nm. The reduction amount of the deposit DP3 in the third experiment was 13.7 nm.

[0126] By comparing the first experiment with the second and third experiments, it was revealed that when the deposit is a metal-containing deposit DP, the metal-containing deposit DP can adequately protect the first region R1 and the third region R3 during the etching in step ST5. This makes it possible to prevent the first region R1 and the third region R3 from being eroded by the metal-containing deposit DP (tungsten-containing deposit) during the etching in step ST5. Furthermore, by comparing the second experiment with the third experiment, it was revealed that when nitrogen (N ２ It was revealed that the reduction in the metal-containing deposits DP was smaller when the second process gas contained argon (Ar) gas than when the second process gas contained argon (Ar) gas.

[0127] The results of the first to third experiments show that when the second process gas contains a metal-containing gas, the first region can be prevented from being etched when the second region is etched.

[0128] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E19] below.

[0129] [E1] An etching method comprising: (a) preparing a substrate on a substrate support in a chamber, the substrate including a first region containing silicon and nitrogen and a second region containing silicon and oxygen, the first region having a recess with an aspect ratio of 3 or greater, the recess being filled with the second region; (b) etching a portion of the second region using a first plasma generated from a first process gas to expose the first region; (c) after (b), setting a pressure in the space in the chamber to a pressure higher than the pressure in the space in the chamber during (b), and forming a metal-containing deposit on at least the first region using a second plasma generated from a second process gas containing carbon and / or hydrogen, fluorine, and a metal; and (d) after (c), etching the second region using a third plasma generated from a third process gas different from the first process gas and the second process gas.

[0130] [E2] The etching method according to [E1], wherein in (c), the metal-containing deposit is formed on the second region so that the thickness of the metal-containing deposit on the second region is smaller than the thickness of the metal-containing deposit formed on the first region.

[0131] [E3] The etching method according to [E1] or [E2], wherein in (a), the second region is provided so as to cover the first region, and in (b), the second region is etched using the first plasma until the first region is exposed.

[0132] [E4] The etching method according to any one of [E1] to [E3], wherein the first process gas and the second process gas are the same gas.

[0133] [E5] The etching method according to any one of [E1] to [E4], wherein the first process gas and / or the second process gas contains a carbon-containing gas and / or a hydrogen-containing gas, and a metal-containing gas.

[0134] [E6] The etching method according to claim 5, wherein the metal-containing gas includes at least one selected from the group consisting of a tungsten-containing gas, a molybdenum-containing gas, and a titanium-containing gas.

[0135] [E7] The carbon-containing gas is CH ４ Gas, C ２ H ２ Gas, C ２ H ４ Gas, CH ３ F gas, CH ２ F ２ Gas, CHF ３ The etching method according to [E5] or [E6], further comprising at least one selected from the group consisting of a fluorine-containing gas and a CO gas.

[0136] [E8] The hydrogen-containing gas is H ２ Gas, SiH ４ Gas and NH ３ The etching method according to any one of [E5] to [E7], further comprising at least one selected from the group consisting of:

[0137] [E9] The etching method according to any one of [E1] to [E8], wherein the third process gas contains a fluorine-containing gas.

[0138] [E10] The etching method according to [E9], wherein the fluorine-containing gas includes at least one selected from the group consisting of hydrogen fluoride gas, hydrofluorocarbon gas, and fluorocarbon gas.

[0139] [E11] The etching method according to any one of [E1] to [E10], further comprising the step of: in (c), forming the metal-containing deposit on the second region; and (e) after (c) and before (d), using a fourth plasma generated from a fourth process gas, removing the metal-containing deposit formed on the second region embedded in the recess in the first region by etching with the fourth plasma or sputtering using ions in the fourth plasma.

[0140] [E12] The fourth process gas is N２ The etching method according to [E11], further comprising a fourth process gas and a CO gas, and in (e), the metal-containing deposit on the second region is removed by sputtering of ions generated from the fourth process gas.

[0141] [E13] The etching method according to any one of [E1] to [E12], wherein (d) supplies a bias signal to the substrate support, and (c) does not supply a bias signal to the substrate support, or supplies a bias signal having a power level lower than that of (d).

[0142] [E14] The etching method according to [E13], wherein in (d), a DC voltage pulse having a frequency of 100 kHz to 800 kHz and an absolute value of 100 V to 1000 V is applied to the substrate support part as the bias signal.

[0143] [E15] The etching method according to any one of [E1] to [E14], wherein a cycle including (c) and (d) is repeated.

[0144] [E16] The etching method according to any one of [E1] to [E15], further comprising: (f) removing the metal-containing deposit after (d).

[0145] [E17] The etching method according to any one of [E1] to [E17], wherein the recess has an aspect ratio of 4 or more, 5 or more, or 10 or more.

[0146] [E18] A plasma processing apparatus comprising: a chamber providing a plasma processing space; a gas supply unit configured to supply a gas into the chamber; a substrate support unit provided in the chamber and configured to support a substrate; a plasma generation unit configured to generate plasma from the gas; and a control unit, wherein at least a portion of a portion exposed to the plasma processing space is made of a conductor, and the control unit controls the gas supply unit and the plasma generation unit to: (a) prepare the substrate on the substrate support unit in the chamber, the substrate including a first region containing silicon and nitrogen and a second region containing silicon and oxygen, the first region having a recess with an aspect ratio of 3 or more, the recess being filled with the second region; and (b) etch a portion of the second region using a first plasma generated from a first processing gas containing carbon and / or hydrogen, fluorine, and a metal. (c) after (b), setting a pressure in the space within the chamber to a pressure higher than the pressure in the space within the chamber in (b), and forming a metal-containing deposit on at least the first region using the first plasma; and (d) after (c), etching the second region using a second plasma generated from a second process gas different from the first process gas.

[0147] [E19] The plasma processing apparatus described in [E18], further comprising: an upper electrode provided above the substrate support, which is part of a ceiling provided above the plasma processing space to close the opening of the chamber, the upper electrode being configured to be able to apply high-frequency power; an insulating portion provided between the upper electrode and the chamber to electrically isolate the upper electrode from the chamber; and a shielding member which is another part of the ceiling, which is conductive, made of a silicon-containing material, and extends from the periphery of the upper electrode to the chamber.

[0148] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims.

[0149] 1...plasma processing apparatus, 2...controller, 10...plasma processing chamber, 10a...sidewall, 10s...plasma processing space, 11...substrate support, 12...plasma generation unit, 13...shower head, 13d...upper electrode, 13e...top plate, 13f...first support, 14...ceiling, 30...power supply, 31...RF power supply, 31a...first RF generation unit, 32...DC power supply, 32b...second DC generation unit, 41...first insulating member, 42...shield member, 43...second support, 45...second insulating member, 46...first insulating portion, 47...second insulating portion, 111...main body, 112...ring assembly, 1110...base, 1111...electrostatic chuck, DP...metal-containing deposit, PL1...first plasma, PL2...second plasma, PL3...third plasma, PL4...fourth plasma, W...substrate.

Claims

1. An etching method comprising: (a) providing a substrate on a substrate support in a chamber, the substrate including a first region containing silicon and nitrogen and a second region containing silicon and oxygen, the first region having a recess with an aspect ratio of 3 or greater, the recess being filled with the second region; (b) etching a portion of the second region using a first plasma generated from a first process gas to expose the first region; (c) after (b), setting a pressure in the space in the chamber higher than the pressure in the space in the chamber during (b), and forming a metal-containing deposit on at least the first region using a second plasma generated from a second process gas containing carbon and / or hydrogen, fluorine, and a metal; and (d) after (c), etching the second region using a third plasma generated from a third process gas different from the first process gas and the second process gas.

2. The etching method of claim 1, wherein in (c), the metal-containing deposit is formed on the second region so that the thickness of the metal-containing deposit on the second region is smaller than the thickness of the metal-containing deposit formed on the first region.

3. The etching method according to claim 1 or 2, wherein in (a), the second region is provided so as to cover the first region, and in (b), the second region is etched using the first plasma until the first region is exposed.

4. The etching method according to claim 1 or 2, wherein the first process gas and the second process gas are the same gas.

5. The etching method according to claim 1 or 2, wherein the first process gas and / or the second process gas contains a carbon-containing gas and / or a hydrogen-containing gas, and a metal-containing gas.

6. The etching method according to claim 5, wherein the metal-containing gas comprises at least one selected from the group consisting of a tungsten-containing gas, a molybdenum-containing gas, and a titanium-containing gas.

7. The carbon-containing gas is CH ４ Gas, C ２ H ２ Gas, C ２ H ４ Gas, CH ３ F gas, CH ２ F ２ Gas, CHF ３ 6. The etching method according to claim 5, wherein the gas comprises at least one selected from the group consisting of a nitrogen gas and a carbon monoxide gas.

8. The hydrogen-containing gas is H ２ Gas, SiH ４ Gas and NH ３ 6. The etching method of claim 5, further comprising at least one selected from the group consisting of:

9. The etching method of claim 1 or 2, wherein the third process gas comprises a fluorine-containing gas.

10. The etching method according to claim 9, wherein the fluorine-containing gas includes at least one selected from the group consisting of hydrogen fluoride gas, hydrofluorocarbon gas, and fluorocarbon gas.

11. The etching method according to claim 1 or 2, wherein in (c), the metal-containing deposit is formed on the second region, and the etching method further comprises the step of: (e) after (c) and before (d), using a fourth plasma generated from a fourth process gas, removing the metal-containing deposit formed on the second region embedded in the recess of the first region by etching with the fourth plasma or sputtering using ions in the fourth plasma.

12. The fourth process gas is N ２ 12. The etching method of claim 11, further comprising a fourth process gas and a CO gas, wherein in step (e), the metal-containing deposit on the second region is removed by sputtering of ions generated from the fourth process gas.

13. The etching method according to claim 1 or 2, wherein (d) supplies a bias signal to the substrate support, and (c) does not supply a bias signal to the substrate support or supplies a bias signal having a power level lower than that of (d).

14. The etching method according to claim 13, wherein in (d), a DC voltage pulse having an absolute value of 100 V or more and 1000 V or less at a frequency of 100 kHz or more and 800 kHz or less is applied to the substrate support portion as the bias signal.

15. The etching method according to claim 1 or 2, wherein a cycle including steps (c) and (d) is repeated.

16. The etching method according to claim 1 or 2, further comprising the step of: (f) removing the metal-containing deposit after (d).

17. The etching method according to claim 1 or 2, wherein the aspect ratio of the recess is 4 or more, 5 or more, or 10 or more.

18. A plasma processing apparatus comprising: a chamber providing a plasma processing space; a gas supply unit configured to supply a gas into the chamber; a substrate support unit provided in the chamber and configured to support a substrate; a plasma generation unit configured to generate plasma from the gas; and a control unit, wherein at least a portion of a portion exposed to the plasma processing space is made of a conductor, and the control unit controls the gas supply unit and the plasma generation unit to: (a) prepare the substrate on the substrate support unit in the chamber, the substrate including a first region containing silicon and nitrogen and a second region containing silicon and oxygen, the first region having a recess with an aspect ratio of 3 or more, the recess being filled with the second region; and (b) etch a portion of the second region using a first plasma generated from a first processing gas containing carbon and / or hydrogen, fluorine, and a metal. (c) after (b), setting a pressure in the space within the chamber to a pressure higher than the pressure in the space within the chamber in (b), and forming a metal-containing deposit on at least the first region using the first plasma; and (d) after (c), etching the second region using a second plasma generated from a second process gas different from the first process gas.

19. The plasma processing apparatus of claim 18, further comprising: an upper electrode provided above the substrate support, which is part of a ceiling provided above the plasma processing space to close the opening of the chamber and is configured to be able to apply high-frequency power; an insulating portion provided between the upper electrode and the chamber to electrically isolate the upper electrode from the chamber; and a shielding member which is another part of the ceiling, which is conductive, made of a silicon-containing material, and extends from the periphery of the upper electrode to the chamber.

Images