Etching method and plasma processing device

Abstract

Disclosed is an etching method including a step for etching a second region by generating plasma from processing gas. The step includes steps (c1)-(c3). In the step (c1), a source high-frequency signal having a first frequency is supplied to generate plasma in a first period. In the step (c2), the power level of the source high-frequency signal in the first period is lowered in a second period alternating with the first period. In the step (c3), in order to draw ions in the second period, a sequence of voltage pulses having a second frequency different from the first frequency is applied to a substrate support unit. The second period is in the range of 10 microseconds to 100 microseconds, inclusive. The voltage pulse has a second frequency of 50 kHz to 800 kHz, inclusive, and has a voltage level that changes in a rectangular shape or a substantially rectangular shape.

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] Patent Document 1 discloses a method for selectively etching a first region made of silicon oxide relative to a second region made of silicon nitride by plasma processing of a substrate. The second region has a recess. The first region is provided to fill the recess and cover the second region. The first region is etched by plasma generated from a process gas containing fluorocarbon.

[0003] Japanese Patent Application Laid-Open No. 2016-157793

[0004] The present disclosure provides a technique for suppressing lateral expansion of an etching profile while increasing verticality.

[0005] In one exemplary embodiment, an etching method is provided. The etching method includes the following steps (a), (b), and (c): Step (a) includes providing a substrate 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. Step (b) includes supplying a process gas containing a metal and an etching component into the chamber. Step (c) includes etching the second region by generating a plasma from the process gas while step (b) is being performed. Step (c) includes steps (c1), (c2), and (c3). Step (c1) includes supplying a source radio frequency signal having a first frequency in a first period to generate a plasma from the process gas in the chamber. Step (c2) includes reducing the power level of the source radio frequency signal from the power level in the first period in second periods alternating with the first period. Step (c3) applies a sequence of voltage pulses having a second frequency different from the first frequency to the substrate support during a second period of time in the range of 10 microseconds to 100 microseconds, the voltage pulses having the second frequency in the range of 50 kHz to 800 kHz, and having voltage levels varying in a rectangular or nearly rectangular pattern to attract ions from the plasma to the substrate support.

[0006] According to the present disclosure, it is possible to improve the verticality of the etching shape while suppressing the lateral expansion.

[0007] 1 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 of an example substrate related to the etching method according to an exemplary embodiment. FIG. 7 is a cross-sectional view of an example substrate related to the etching method according to an exemplary embodiment. FIG. 8 is an example of a timing chart showing time changes of a source RF signal, a bias RF signal, and a bias DC signal in one step of the etching method according to an exemplary embodiment. FIG. 9 is a cross-sectional view of an example substrate related to the etching method according to an exemplary embodiment. FIG. 10 is a cross-sectional view of an example substrate related to the etching method according to an exemplary embodiment. FIG. 11 is a cross-sectional view of an example substrate related to the etching method according to an exemplary embodiment. A diagram for explaining a plasma processing apparatus according to another exemplary embodiment.

[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 at least one third insulating member 44 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 flowing based on the source RF signal, i.e., the radio frequency power, supplied to the upper electrode 13d can be classified into two possible 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, at least one third insulating member 44, 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 at least one third insulating member 44 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-described embodiment. When the plasma processing apparatus 1 is used, the method MT can be performed in the plasma processing apparatus 1 by the control of each part of the plasma processing apparatus 1 by the control unit 2.

[0046] 4, the method MT may include steps ST1, ST2, ST3, and ST4. Steps ST1 to ST4 may be performed in order.

[0047] In step ST1, a substrate W is prepared. The substrate W is transferred by a transfer device (not shown) into the plasma processing chamber 10. The substrate W can be supported by a substrate support 11 in the plasma processing chamber 10.

[0048] Figure 5 is a partially enlarged cross-sectional view of an example substrate to which the method of Figure 4 can be applied. The example substrate W shown in Figure 5 can be processed by the method MT. As shown in Figure 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.

[0049] In one embodiment, the first region R1 includes silicon and nitrogen. The first region R1 includes silicon nitride (SiN ｘ The first region R1 may include a silicon nitride (SiN 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The substrate W prepared in step ST1 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 it is provided to the plasma processing chamber 10.

[0056] In the method MT, step ST2 is then performed. In step ST2, the control unit 2 controls the gas supply unit 20 to supply a processing gas.

[0057] The processing gas includes a metal and an etching component. In one example, the processing gas may include a metal-containing gas. The processing gas may include an etching component-containing gas. The processing gas may include a carbon-containing gas. The processing gas may include a hydrogen-containing gas. In another example, the processing 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 as a metal-containing gas immediately before the first region R1 is exposed. In one example, the processing gas includes a halide gas as an etching component. The metal-containing gas may be a metal halide-containing gas. The etching component is a component that etches the second region R2.

[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) ６ The 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 tetrachloride (TiCl ４ ) may also be included.

[0059] The etching component-containing gas includes a halogenated gas. The halogenated gas may include at least one selected from the group consisting of a fluorine-containing gas, a chlorine-containing gas, and a bromine-containing gas. The fluorine-containing gas may include a fluorocarbon gas.

[0060] The carbon-containing gas is CH ４ Gas, C ２ H２ 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 nitrogen gas and a CO gas.

[0061] 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:

[0062] The process gas may further include a noble gas, such as argon gas, helium gas, xenon gas, or neon gas. ２ ) gas.

[0063] In the method MT, step ST3 is next performed. Step ST3 is performed during the period in which step ST2 is being performed. As shown in FIG. 6 or 7 , in step ST3, the control unit 2 controls the plasma generating unit 12 to etch a portion of the second region R2 using plasma PL generated from the processing gas. As shown in FIG. 6 , the control unit 2 controls the gas supply unit 20 and the plasma generating unit 12 to expose the first region R1 and etch the second region R2. In step ST3, the second region R2 can be etched to expose a shoulder portion SH of the recess R1a of the first region R1. As shown in FIG. 7 , in step ST3, the second region R2 in the recess R1a of the first region R1 is etched, thereby exposing the underlying region UR.

[0064] 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, silicon is released into the plasma PL when noble gas ions in the plasma PL collide with the counter electrode. When sputtering is performed after step ST3, the sputtering may be performed using plasma PL generated from a process gas containing a noble gas.

[0065] In step ST4, it is determined whether the etching stop condition of step ST3 is satisfied. This determination can be made by the control unit 2. If it is determined that the stop condition is satisfied, the method MT ends and proceeds to step ST4. If it is determined that the stop condition is not satisfied, the process returns to step ST2. The stop condition includes, for example, removal of the second region R2 in the recess R1a as shown in FIG. 7.

[0066] Next, details of step ST3 will be described with reference to FIG. 8 . FIG. 8 is an example of a timing chart showing temporal changes of a source RF signal, a bias RF signal, and a bias DC signal in one step of an etching method according to an exemplary embodiment. As shown in FIG. 8 , in step ST3, a period CY may be repeated. The frequency defining the period CY may be 0.01 kHz or more and 50 kHz or less. The frequency defining the period CY is the reciprocal of the time length of the period CY. The period CY may include a first period PA and a second period PB. The second period PB is the period following the first period PA. In step ST3, one cycle corresponding to the period CY may be repeated two or more times. In this case, the first period PA and the second period PB appear alternately. The first period PA may include a first sub-period PA1, a second sub-period PA2, and a third sub-period PA3. The first sub-period PA1, the second sub-period PA2, and the third sub-period PA3 appear in order within the first period PA.

[0067] During the first period PA, a source RF signal (an example of a source RF signal) having a first frequency may be supplied to the RF electrode to generate plasma from the processing gas in the plasma processing chamber 10. The source RF signal may be provided to the RF electrode from a first RF generating unit 31a (an example of a first RF power supply). The RF electrode may be an upper electrode or a lower electrode. During the first period PA, a source RF signal having a first frequency of 60 MHz to 200 MHz may be supplied. During the first period PA, the controller 2 may set the power level of the source RF signal to a first power level of 100 W to 1000 W. During the first period PA, the controller 2 may set the power level of the source RF signal to a first power level of 200 W to 800 W. During the first period PA, the controller 2 may set the power level of the source RF signal to a first power level of 300 W to 500 W. The control unit 2 of this embodiment may set the power level of the source RF signal to a first power level of 500 W or more and 1000 W or less during the first period PA.

[0068] The first period PA may include a period during which a bias RF signal (an example of a bias high frequency signal) is not supplied to the lower electrode. For example, during the first sub-period PA1 and the third sub-period PA3 of the first period PA, a bias RF signal is not supplied from the second RF generating unit 31b (an example of a second high frequency power supply) to the lower electrode in the main body 111 of the substrate support unit 11. In one example, during the first sub-period PA1 and the third sub-period PA3, the control unit 2 may set the power level of the bias RF signal to a first power level. The first power level may be zero.

[0069] The first period PA may include a period during which the bias DC signal is not supplied to the lower electrode. For example, during the first sub-period PA1, the second sub-period PA2, and the third sub-period PA3 of the first period PA, the bias DC signal is not supplied from the first DC generating unit 32a to the lower electrode in the main body 111 of the substrate support member 11. In one example, during the first period PA, the control unit 2 may set the voltage level of the bias DC signal to a first voltage level. The first voltage level may be zero.

[0070] During at least a portion of the first period PA, a bias RF signal (an example of a bias RF signal) may be supplied to the lower electrode. For example, during a second sub-period PA2 of the first period PA, a bias RF signal may be supplied from the second RF generating unit 31b to the lower electrode in the main body 111 of the substrate support unit 11. During the second sub-period PA2, a bias RF signal having a second frequency of 3 MHz or more and 40 MHz or less may be supplied. For example, during the second sub-period PA2, a source RF signal having a frequency of 27 MHz or more and 100 MHz or less may be supplied. For example, during the second sub-period PA2, the control unit 2 may set the power level of the bias RF signal to a second power level. The second power level is higher than the first power level. The second power level may be greater than 0 W and less than 100 W.

[0071] During the second period PB, the power level of the source RF signal is reduced from the power level of the source RF signal during the first period PA. During the second period PB, the control unit 2 may stop the supply of the source RF signal from the first RF generation unit 31a. Alternatively, during the second period PB, the control unit 2 may set the power level of the source RF signal to a power level greater than 0 W and equal to or less than 50 W. In other words, the power level of the source RF signal during the second period PB is maintained at a power level lower than the power level of the source RF signal during the first period PA.

[0072] During the second period PB, a bias DC signal may be supplied to the lower electrode. For example, the bias DC signal may be supplied from the first DC generator 32a to the lower electrode in the main body 111 of the substrate support 11. The bias DC signal is a sequence of voltage pulses, i.e., a pulsed first DC signal. The voltage level (pulse wave) of the voltage pulses generated by the bias DC signal varies in a rectangular or substantially rectangular shape. The voltage level (pulse wave) of the voltage pulses generated by the bias DC signal may include a rectangular pulse, a triangular pulse, an impulse, or a pulse of any other waveform. The bias DC signal applied to the lower electrode during the second period PB has a third frequency of 50 kHz or more and 800 kHz or less. That is, the voltage pulses constituting the bias DC signal are periodically applied to the lower electrode at a time interval equal to the reciprocal of the third frequency.

[0073] During the second period PB, the control unit 2 may control the first DC generating unit 32a to supply a bias DC signal to the substrate support unit 11 at a second voltage level. The second voltage level is higher than the first voltage level. Note that the voltage level of the bias DC signal, i.e., the voltage level of the voltage pulse constituting the bias DC signal, is higher the higher the energy of ions attracted to the substrate W by the voltage pulse applied to the lower electrode. Therefore, if the voltage pulse is a negative voltage, the voltage level of the voltage pulse is higher the greater the absolute value of the voltage pulse.

[0074] During the second period PB, as described above, the power level of the source RF signal is reduced from that during the first period PA, and therefore the plasma in the plasma processing space 10s becomes an afterglow plasma, in which the fluorine flux, ion flux, and electron density each decrease over time.

[0075] The details and effects of the etching method including the afterglow etching in step ST3 will be described below with reference to FIGS. 6 to 11. In the following example, the processing gas contains a tungsten-containing gas as a metal-containing gas. In the following example, the processing gas contains fluorine as an etching component-containing gas.

[0076] During the first period PA, as shown in FIG. 9 , a metal-containing deposit DP is formed on at least the first region R1 by plasma PL generated from the process gas. During the first period PA, the plasma PL may be used to form the metal-containing deposit DP on the surface of the first region R1 and / or 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. The metal-containing deposit DP includes a metal component contained in the metal-containing gas, including tungsten or a tungsten compound. In one example, during the first period PA, chemical species including tungsten fluoride are supplied from the plasma to the first region R1 and the second region R2, thereby depositing the metal-containing deposit DP on the surfaces of the first region R1 and the second region R2.

[0077] 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. 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.

[0078] After the first sub-period PA1 ends, a bias RF signal is supplied to the substrate support 11 during the second sub-period PA2. As a result, as shown in FIG. 10 , ions from the plasma collide with the metal-containing deposit DP, etching a portion of the metal-containing deposit DP. The etched metal-containing deposit DP may adhere to the shoulder portion SH of the first region R1. Note that the bias signal does not need to be applied immediately before or immediately after the first region R1 is exposed. As a result, deposits are more likely to form on the shoulder portion SH of the first region R1, and etching of the shoulder portion SH in the recess R1a is suppressed.

[0079] After the second sub-period PA2 ends, in a third sub-period PA3, a metal-containing deposit DP is deposited on the substrate W. In one example, in the third sub-period PA3, a chemical species including tungsten fluoride may be supplied from the plasma to the metal-containing deposit DP, thereby depositing a new metal-containing deposit DP on the metal-containing deposit DP formed in the second sub-period PA2.

[0080] During the second period PB, a bias DC signal is supplied to the substrate support 11 while the power level of the source RF signal is reduced, thereby performing afterglow etching. During the second period PB, the amount of flux of an etching component (e.g., fluorine) is reduced. Furthermore, during etching during the second period PB, the first region R1 is protected by the metal-containing deposit DP. Therefore, the method MT improves the etching selectivity of the second region R2 relative to the first region R1. Furthermore, the method MT suppresses etching of the shoulder portion SH, which is protected by the metal-containing deposit DP.

[0081] Furthermore, since the bias DC signal used in the second period PB, i.e., the waveform of the voltage pulse, is rectangular or approximately rectangular, the voltage level of the bias DC signal is approximately constant. Therefore, the ions attracted to the substrate W by the bias DC signal have energy with reduced variation compared to when a bias RF signal is used. That is, the energy of the ions attracted to the substrate W by the bias DC signal has high monochromaticity. Therefore, when the bias DC signal is used, the ions are supplied with high perpendicularity to the substrate W. Therefore, the verticality of the etching of the second region R2 is increased, and lateral expansion of the etching shape is suppressed.

[0082] In the method MT, one cycle corresponding to a period CY including a first period PA and a second period PB is repeatedly performed from the state shown in Fig. 6 or 11. As a result, the second region R2 in the recess R1a of the first region R1 is etched, and the underlying region UR is exposed, as shown in Fig. 7. Note that the etching in the second period PB may reduce the amount of metal-containing deposits DP on the substrate W or may even eliminate the metal-containing deposits DP.

[0083] During the second period PB, if the amount of fluorine flux is sufficient, the metal-containing deposit DP on the second region R2 is removed as volatile tungsten oxide fluoride and does not inhibit etching of the second region R2. However, as described above, the amount of fluorine flux is reduced during the second period PB, and the metal-containing deposit DP on the second region R2 is likely to change to non-volatile tungsten oxide. If a large amount of tungsten oxide is formed from the metal-containing deposit DP on the second region R2, etching of the second region R2 may be inhibited.

[0084] Here, the amount of tungsten oxide formed from the metal-containing deposit DP is proportional to the product of the ion energy and the ion flux during the second period PB. As described above, a bias DC signal is used during the second period PB. As described above, the energy of the ions attracted to the substrate W by the bias DC signal is highly monochromatic. Therefore, according to the method MT, the ion energy during the second period PB is highly controllable. Furthermore, according to the method MT, the time length of the second period PB and the ON duty of the voltage pulse of the bias DC signal can be adjusted. Therefore, according to the method MT, the ion flux during the second period PB is highly controllable. Therefore, according to the method MT, the formation of tungsten oxide from the metal-containing deposit DP on the second region R2 is suppressed, and etching of the second region R2 is prevented from stopping.

[0085] The voltage level of the voltage pulse of the bias DC signal in the second period PB, the time length of the second period PB, and the ON duty of the voltage pulse of the bias DC signal are controlled by the control unit 2. The time length of the second period PB is set to, for example, a range of 10 microseconds to 100 microseconds.

[0086] During the second period PB, the bias DC signal applied to the lower electrode may have a second frequency of 50 kHz or more and 800 kHz or less. If the second frequency is less than 50 kHz, the ion flux will be completely attenuated during one voltage pulse period, making it impossible to sufficiently etch the second region R2. Furthermore, if the second frequency is 2 MHz or more, the bias DC signal will contribute to plasma generation, making it impossible to perform the set etching. Therefore, the second frequency is set to 50 kHz or more and 800 kHz or less.

[0087] Furthermore, the control unit 2 may control the first DC generating unit 32a so that 1 to 80 voltage pulses of the bias DC signal are periodically applied to the lower electrode during the second period PB.

[0088] 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.

[0089] For example, in process ST3, the power supply 30 may be controlled according to a timing chart other than that shown in FIG. 8 . For example, the first period PA may include a first sub-period PA1, a second sub-period PA2, a third sub-period PA3, and a fourth sub-period. The fourth sub-period is the period immediately following the third sub-period PA3. During the fourth sub-period, the control unit 2 may control the first DC generating unit 32a to supply a bias DC signal to the substrate support unit 11 at the second voltage level described above. During the fourth sub-period, the control unit 2 may set the power level of the bias RF signal to the first power level described above. Note that the second period PB continues after the fourth sub-period. Therefore, the bias DC signal continues to be supplied from the first DC generating unit 32a during the second period PB even after the end of the fourth sub-period.

[0090] The first period PA does not have to include the third sub-period PA3. That is, the first period PA may include the first sub-period PA1, the second sub-period PA2, and the fourth sub-period, and the fourth sub-period may appear immediately after the second sub-period PA2.

[0091] The metal-containing deposit DP varies depending on the type of metal-containing gas contained in the 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 oxygen. The metal-containing deposit DP may be a tungsten oxide (WO ｘ During the execution of step ST2, the maximum thickness of the metal-containing deposit DP may be 5 nm or more.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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 .

[0097] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E19] below.

[0098] [E1] A method of etching 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; (b) supplying a process gas containing a metal and an etching component into the chamber; and (c) while (b) is being performed, generating a plasma from the process gas to etch the second region, wherein (c) comprises: (c1) during a first time period, supplying a source radio frequency signal having a first frequency to generate a plasma from the process gas in the chamber; (c2) during second time periods alternating with the first time period, reducing the power level of the source radio frequency signal from the power level of the source radio frequency signal during the first time period; and (c3) during the second time period, applying a sequence of voltage pulses to the substrate support having a second frequency different from the first frequency to attract ions from the plasma to the substrate support. the second period is in the range of 10 microseconds to 100 microseconds, and the voltage pulse has the second frequency of 50 kHz to 800 kHz, and has voltage levels that vary in a rectangular or nearly rectangular pattern.

[0099] [E2] A method of manufacturing a plasma processing chamber, 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; (b) supplying a process gas containing a metal and an etching component into the chamber; and (c) while (b) is being performed, generating a plasma from the process gas to form a deposit on the first region and / or the second region and to etch the second region, wherein (c) comprises: (c1) during a first time period, supplying a source radio frequency signal having a first frequency to generate a plasma from the process gas in the chamber; (c2) during second time periods alternating with the first time period, reducing the power level of the source radio frequency signal from the power level of the source radio frequency signal in the first time period; and (c3) during the second time period, applying a sequence of voltage pulses to the substrate support having a second frequency different from the first frequency to attract ions from the plasma to the substrate support. In the etching method (c3), the voltage pulse has the second frequency of 50 kHz to 800 kHz, has a voltage level that changes in a rectangular or approximately rectangular shape, and is applied so that the number of pulses during the second period is 1 to 80.

[0100] [E3] The etching method according to [E1] or [E2], wherein (c) further comprises: (c4) supplying a bias radio frequency signal having a third frequency lower than the first frequency and different from the second frequency to the substrate support portion during a portion of the first period, in order to attract ions from the plasma to the substrate support portion.

[0101] [E4] The etching method according to [E3], wherein in (c4), the bias high frequency signal is supplied having the third frequency of 3 MHz or more and 40 MHz or less and a power level of more than 0 W and less than 100 W.

[0102] [E5] The etching method according to any one of [E1] to [E4], wherein in (a), the first region has a recess, and the recess is filled with the second region.

[0103] [E6] The etching method according to [E3], wherein in (a), the second region covers the first region, and the etching method further comprises: (d) exposing the first region by etching a part of the second region using plasma generated from the processing gas while (b) is being performed and before (c) is being performed.

[0104] [E7] The etching method according to any one of [E1] to [E6], wherein in (c1), the source high frequency signal is supplied having the first frequency of 60 MHz to 200 MHz and a power level of 500 W to 1000 W.

[0105] [E8] The etching method according to any one of [E1] to [E7], wherein in (c2), the supply of the source high frequency signal is stopped, or the power level of the source high frequency signal is set to more than 0 W and not more than 50 W.

[0106] [E9] The etching method according to any one of [E1] to [E8], wherein in (c1), the reciprocal of the time length of the period of the source high frequency signal, including the first period and the second period, is 0.1 kHz or more and 50 kHz or less.

[0107] [E10] The etching method according to any one of [E1] to [E9], wherein the processing gas further contains fluorine, and the metal-containing gas contains at least one selected from the group consisting of a tungsten-containing gas, a molybdenum-containing gas, a titanium-containing gas, and a ruthenium-containing gas.

[0108] [E11] The etching method according to any one of [E1] to [E10], wherein the processing gas further contains a carbon-containing gas.

[0109] [E12] The etching method according to any one of [E1] to [E11], wherein the processing gas further contains a hydrogen-containing gas or a CO-containing gas.

[0110] [E13] The etching method according to any one of [E1] to [E12], wherein the processing gas further contains an inert gas.

[0111] [E14] 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 radio frequency power supply configured to supply a source radio frequency signal having a first frequency to generate plasma from the gas; a DC power supply configured to apply a DC voltage to the substrate support unit; and a controller configured to control the gas supply unit, the radio frequency power supply, and the DC power supply, wherein at least a portion of a portion exposed to the plasma processing space is made of a conductor, and the controller is configured to perform the following steps: (a) preparing a 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; (b) supplying a process gas containing a metal and an etching component into the chamber; and (c) generating plasma from the process gas while (b) is being performed, thereby etching the second region, wherein (c) is selected from the group consisting of: (c1) (c2) during a first period, supplying a source radio frequency signal having a first frequency from the radio frequency power supply to generate plasma from the process gas in the chamber; and (c3) during a second period alternating with the first period, reducing the power level of the source radio frequency signal from the power level of the source radio frequency signal in the first period; and (c3) during the second period, applying a sequence of voltage pulses from the DC power supply to the substrate support, the voltage pulses having a second frequency different from the first frequency, to attract ions from the plasma to the substrate support, wherein the second period is in a range of 10 microseconds to 100 microseconds, and the voltage pulses have the second frequency in a range of 50 kHz to 800 kHz, and have voltage levels that vary in a rectangular or approximately rectangular pattern.

[0112] [E15] 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 radio frequency power supply configured to supply a source radio frequency signal having a first frequency to generate plasma from the gas; a DC power supply configured to apply a DC voltage to the substrate support unit; and a controller configured to control the gas supply unit, the radio frequency power supply, and the DC power supply, wherein at least a portion of a portion exposed to the plasma processing space is made of a conductor, and the controller is configured to perform the following steps: (a) preparing a 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; (b) supplying a process gas containing a metal and an etching component into the chamber; and (c) generating plasma from the process gas while (b) is being performed, thereby etching the second region, wherein (c) is selected from the group consisting of: (c1) (c2) during a first period, supplying a source radio frequency signal having a first frequency from the radio frequency power supply to generate plasma from the process gas in the chamber; and (c3) during a second period alternating with the first period, reducing the power level of the source radio frequency signal from the power level of the source radio frequency signal in the first period; and (c3) during the second period, applying a sequence of voltage pulses from the DC power supply to the substrate support, the voltage pulses having a second frequency different from the first frequency, to attract ions from the plasma to the substrate support, wherein in (c3), the voltage pulses have the second frequency of 50 kHz to 800 kHz, have voltage levels that vary in a rectangular or approximately rectangular shape, and are applied such that the number of pulses during the second period is 1 to 80.

[0113] [E16] The plasma processing apparatus according to [E14] or [E15], 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 part 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.

[0114] 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.

[0115] 1...plasma processing apparatus, 2...controller, 10...plasma processing chamber, 10a...sidewall, 10s...plasma processing space, 11...substrate support, 12...plasma generation section, 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 section, 32...DC power supply, 32b...second DC generation section, 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, W...substrate.

Claims

1. A method for etching 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; (b) supplying a process gas containing a metal and an etching component into the chamber; and (c) while (b) is being performed, etching the second region by generating a plasma from the process gas, wherein (c) comprises: (c1) during a first time period, supplying a source radio frequency signal having a first frequency to generate a plasma from the process gas in the chamber; (c2) during a second time period alternating with the first time period, reducing the power level of the source radio frequency signal from the power level during the first time period; and (c3) during the second time period, applying a sequence of voltage pulses to the substrate support having a second frequency different from the first frequency to attract ions from the plasma to the substrate support, the second time period being in the range of 10 to 100 microseconds, The etching method, wherein the voltage pulse has the second frequency of 50 kHz to 800 kHz, and has a voltage level that changes in a rectangular or approximately rectangular shape.

2. (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; (b) supplying a process gas into the chamber, the process gas including a metal-containing gas; and (c) while (b) is being performed, generating a plasma from the process gas to form a deposit on the first region and / or the second region and to etch the second region, wherein (c) comprises: (c1) during a first time period, supplying a source radio frequency signal having a first frequency to generate a plasma from the process gas in the chamber; (c2) during second time periods alternating with the first time period, reducing the power level of the source radio frequency signal from the power level during the first time period; and (c3) during the second time period, applying a sequence of voltage pulses to the substrate support, the second frequency being different from the first frequency, to attract ions from the plasma to the substrate support. In the etching method (c3), the voltage pulse has the second frequency of 50 kHz to 800 kHz, has a voltage level that changes in a rectangular or approximately rectangular shape, and is applied so that the number of pulses during the second period is 1 to 80.

3. The etching method according to claim 1 or 2, wherein (c) further comprises the step of: (c4) supplying a bias radio frequency signal having a third frequency lower than the first frequency and different from the second frequency to the substrate support during a portion of the first period in order to attract ions from the plasma to the substrate support.

4. The etching method according to claim 3, wherein in (c4), the bias high frequency signal is supplied having a power level greater than 0 W and less than 100 W at the third frequency of 3 MHz or more and 40 MHz or less.

5. The etching method according to claim 1 or 2, wherein in (a), the first region has a recess, and the recess is filled with the second region.

6. The etching method according to claim 3, wherein in (a), the second region covers the first region, and the etching method further comprises: (d) exposing the first region by etching a portion of the second region using plasma generated from the processing gas while (b) is being performed and before (c) is being performed.

7. The etching method according to claim 1 or 2, wherein in (c1), the source high frequency signal is supplied having the first frequency of 60 MHz or more and 200 MHz or less and a power level of 500 W or more and 1000 W or less.

8. The etching method according to claim 1 or 2, wherein in (c2), the supply of the source high frequency signal is stopped or the power level of the source high frequency signal is set to more than 0 W and not more than 50 W.

9. An etching method according to claim 1 or 2, wherein in (c1), the reciprocal of the time length of the period of the source high frequency signal, including the first period and the second period, is 0.01 kHz or more and 50 kHz or less.

10. The etching method according to claim 1 or 2, wherein the processing gas further contains fluorine as an etching component, and the processing gas contains, as a metal, at least one selected from the group consisting of a tungsten-containing gas, a molybdenum-containing gas, a titanium-containing gas, and a ruthenium-containing gas.

11. The etching method according to claim 1 or 2, wherein the process gas further comprises a carbon-containing gas.

12. The etching method according to claim 1 or 2, wherein the process gas further contains a hydrogen-containing gas or a CO-containing gas.

13. The etching method according to claim 1 or 2, wherein the process gas further comprises an inert gas.

14. 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 radio frequency power supply configured to supply a source radio frequency signal having a first frequency to generate plasma from the gas; a DC power supply configured to apply a DC voltage to the substrate support unit; and a controller configured to control the gas supply unit, the radio frequency power supply, and the DC power supply, wherein at least a portion of a portion exposed to the plasma processing space is made of a conductor, and the controller is configured to perform the following steps: (a) preparing a 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; (b) supplying a process gas containing a metal and an etching component into the chamber; and (c) etching the second region by generating plasma from the process gas while (b) is being performed, wherein (c) is (c2) during a first period, supplying a source radio frequency signal having a first frequency from the radio frequency power supply to generate plasma from the process gas in the chamber; and (c3) during the second period, applying a sequence of voltage pulses from the DC power supply to the substrate support, the voltage pulses having a second frequency different from the first frequency, to attract ions from the plasma to the substrate support, the second period being in a range of 10 microseconds to 100 microseconds, and the voltage pulses having a second frequency of 50 kHz to 800 kHz, the voltage pulses having voltage levels that vary in a rectangular or approximately rectangular pattern.

15. 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 radio frequency power supply configured to supply a source radio frequency signal having a first frequency to generate plasma from the gas; a DC power supply configured to apply a DC voltage to the substrate support unit; and a controller configured to control the gas supply unit, the radio frequency power supply, and the DC power supply, wherein at least a portion of a portion exposed to the plasma processing space is made of a conductor, and the controller is configured to perform the following steps: (a) preparing a 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; (b) supplying a process gas containing a metal and an etching component into the chamber; and (c) etching the second region by generating plasma from the process gas while (b) is being performed, wherein (c) is (c2) during a first period, supplying a source radio frequency signal having a first frequency from the radio frequency power supply to generate plasma from the process gas in the chamber; and (c3) during the second period, applying a sequence of voltage pulses from the DC power supply to the substrate support, the voltage pulses having a second frequency different from the first frequency, to attract ions from the plasma to the substrate support, wherein in (c3), the voltage pulses have a second frequency of 50 kHz to 800 kHz, have voltage levels that vary in a rectangular or approximately rectangular shape, and are applied such that the number of pulses is 1 to 80.

16. A plasma processing apparatus as described in claim 14 or 15, 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 part 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