Etching method and plasma processing device

Abstract

Disclosed is an etching method which includes a step for forming a deposit on a first region and / or a second region by generating plasma from a processing gas, and etching the second region. The step includes steps (c1) to (c4). In the step (c1), a source high-frequency signal that has a first frequency is supplied during a first period. In the step (c2), the power level of the source high-frequency signal is reduced from the first period in a second period that alternates with the first period. In the step (c3), a bias high-frequency signal that has a second frequency which is lower than the first frequency is supplied to a substrate support part during a part of the first period. In the step (c4), a sequence of voltage pulses that have a third frequency which is different from the first frequency and the second frequency is supplied to the substrate support part during a part of the second period.

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 carbon and fluorine into the chamber. Step (c) includes generating a plasma from the process gas while step (b) is being performed, thereby forming a deposit on the first region and / or the second region and etching the second region. Step (c) includes steps (c1), (c2), (c3), and (c4). Step (c1) includes providing 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) supplies a bias radio frequency signal having a second frequency lower than the first frequency to the substrate support during a portion of the first time period to draw ions from the plasma to the substrate support, and Step (c4) applies a sequence of voltage pulses having a third frequency different from the first and second frequencies to the substrate support during at least a portion of the second time period to draw 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] FIG. 2 is a diagram illustrating an example of the configuration of a plasma processing system. FIG. 2 is a diagram schematically illustrating a plasma processing apparatus according to an exemplary embodiment. FIG. 3 is a diagram illustrating 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 illustrating time changes of a source radio frequency signal, a bias RF signal, and a bias DC signal in a step of an etching method according to an exemplary embodiment. FIG. 9 is a cross-sectional view of an example substrate related to a substrate processing method according to an exemplary embodiment. FIG. 10 is a cross-sectional view of an example substrate related to a substrate processing method according to an exemplary embodiment. FIG. 11 is a cross-sectional view of an example substrate related to a substrate processing method according to an exemplary embodiment. FIG. 12 is another example of a timing chart illustrating time changes of a source radio frequency signal, a bias RF signal, and a bias DC signal in a step of an etching method according to an exemplary embodiment. Fig. 13 is a partially enlarged cross-sectional view of another example substrate to which the method of Fig. 4 can be applied. Fig. 14 is a cross-sectional view of another example substrate related to the etching method according to an exemplary embodiment. Fig. 15 is a cross-sectional view of another example substrate related to the etching method according to an exemplary embodiment. Fig. 16 is a cross-sectional view of another 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 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-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. The method MT may not include step ST4. Step ST4 may be included in step ST3.

[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] 5 is a partially enlarged cross-sectional view of an example substrate to which the method of FIG. 4 can be applied. The example substrate W shown in FIG. 5 can be processed by the method MT. The substrate W includes a first region R1 and a second region R2. The substrate W may further include a base region UR. The first region R1 and the second region R2 are provided on the base region UR. In one embodiment, the second region R2 is provided on the base region UR, and the first region R1 is provided on the second region R2. The first region R1 is patterned like a mask. That is, the first region R1 provides an opening OP.

[0049] The second region R2 is a region to be selectively etched. The first region R1 is formed of a material different from the material of the second region R2. The materials of the first region R1 and the second region R2 are not limited.

[0050] 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). 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 silicon dioxide may include a first portion including silicon carbide (SiC) and a second portion including silicon carbide (SiC).

[0051] The second region R2 includes silicon and oxygen. The second region R2 includes silicon oxide (SiO ｘThe 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 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. Hereinafter, reference will be made to Figs. 6 and 7 in addition to Figs. 4 and 5. Each of Figs. 6 and 7 is a cross-sectional view of an example substrate related to a substrate processing method according to one exemplary embodiment.

[0053] 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 process gas into the plasma processing chamber 10. The process gas contains carbon and fluorine. The process gas contains 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 nitrogen gas and a CO gas.

[0054] The processing gas may contain at least one gas selected from the group consisting of a hydrofluorocarbon gas and a fluorocarbon gas as a fluorine-containing gas. A fluorocarbon gas (CF-based gas) is a gas containing C and F, such as C ４ F ８ Gas, C ５ F ８ Gas, C ４ F ６ Hydrofluorocarbon gas (CHF-based gas) is a gas containing C, H, and F, such as CHF ３ Gas, CH ２ F ２ Gas, etc.

[0055] The process gas may further include an oxygen-containing gas and a noble gas. ２The noble gas may include at least one selected from the group consisting of a nitrogen gas and a carbon monoxide gas. The noble gas may include an Ar gas or the like.

[0056] The process gas may further include 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. 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 halide gas. The titanium halide gas may include titanium tetrachloride (TiCl ４ ), titanium tetrafluoride (TiF ４ ) and titanium tetrabromide (TiBr ４ The ruthenium-containing gas may include at least one selected from the group consisting of ruthenium chloride (RuCl ４ ) gas, and ruthenium carbonyl (Ru(CO) ６ ) may contain at least one selected from the group consisting of

[0057] Next, step ST3 is performed. Step ST3 is performed while step ST2 is being performed. In step ST3, the control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to form deposits DP on the first region R1 and the second region R2 using plasma generated from the processing gas. In step ST3, deposits DP may be formed on the surfaces of the first region R1 and the second region R2 as shown in FIG. 6 during at least a portion of a first period PA described below. The deposits DP include fluorocarbon.

[0058] In step ST3, the control unit 2 controls the plasma generating unit 12 to generate plasma from the processing gas in the plasma processing chamber 10. The control unit 2 controls the gas supplying unit 20 and the plasma generating unit 12 to form a deposit DP on at least the first region R1. The control unit 2 may also control the gas supplying unit 20 and the plasma generating unit 12 to form a deposit DP on the second region R2.

[0059] Furthermore, in step ST3, the control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to etch the second region R2 using plasma generated from the processing gas. The control unit 2 may etch the second region R2 using plasma during at least a part of a second period PB described below.

[0060] In the subsequent 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 is terminated. If it is determined that the stop condition is not satisfied, the process returns to step ST3. The stop condition may include, for example, that the second region R2, which is not provided with the first region R1 above it, is removed down to the underlying region UR, as shown in FIG. 7. In one embodiment, step ST3 is repeated until the stop condition is satisfied. In this embodiment, the control unit 2 repeatedly executes the control sequence to repeat step ST3.

[0061] After step ST4, the control unit 2 may remove the deposit DP. After the second region R2 is removed in step ST3, the deposit DP may remain on the first region R1. The deposit DP may be removed by cleaning after step ST4.

[0062] Here, the changes over time of the source radio frequency signal, the bias RF signal, and the bias DC signal in step ST3 will be described with reference to Fig. 8. Fig. 8 is an example of a timing chart showing the changes over time of the source radio frequency signal, the bias RF signal, and the bias DC signal in one step of an etching method according to one example embodiment.

[0063] In step ST3, a source RF signal (an example of a source high frequency signal) may be applied to a high frequency electrode from a first RF generating unit 31a (an example of a first high frequency power supply). The high frequency electrode may be an upper electrode or a lower electrode. In step ST3, a source RF signal having a first frequency of 60 MHz or more and 200 MHz or less may be supplied. The source RF signal may be supplied periodically with a period CY. The frequency defining the period CY may be 0.1 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.

[0064] In process ST3, a bias RF signal (an example of a bias RF signal) may be 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 11. In process ST3, a bias RF signal having a second frequency of 3 MHz or more and 40 MHz or less may be supplied.

[0065] The bias DC signal can 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, which is a pulsed first DC signal. The bias DC signal applied to the lower electrode in step ST3 has a third frequency of 100 kHz or more and 800 kHz or less. That is, the voltage pulses constituting the bias DC signal are applied to the lower electrode periodically at a time interval that is the reciprocal of the third frequency.

[0066] The above-mentioned period CY may include a first period PA and a second period PB. One cycle corresponding to the period CY including the first period PA and the second period PB may be repeated two or more times. In this case, the first period PA and the second period PB appear alternately. During the first period PA, the control unit 2 controls the first RF generating unit 31a to supply a source RF signal. During the first period PA, the control unit 2 may set the power level of the source RF signal to a power level of 500 W or more and 1000 W or less.

[0067] The first period PA may include a first sub-period PA1, a second sub-period PA2, and a third sub-period PA3. In the first sub-period PA1, the control unit 2 may set the power level of the bias RF signal to a first power level. In the first sub-period PA1, the control unit 2 may set the voltage level of the bias DC signal to a first voltage level. The first power level and / or the first voltage level may be zero.

[0068] The second sub-period PA2 is a period following the first sub-period PA1. 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. During the second sub-period PA2, the control unit 2 may set the voltage level of the bias DC signal to the substrate support 11 to a first voltage level.

[0069] The third sub-period PA3 is a period following the second sub-period PA2. In the third sub-period PA3, the control unit 2 may set the power level of the bias RF signal to the first power level. In the third sub-period PA3, the control unit 2 may set the voltage level of the bias DC signal to the first voltage level.

[0070] During the second period PB, the control unit 2 reduces the power level of the source RF signal 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.

[0071] The second period PB may include sub-periods PB1 and PB2. Sub-period PB1 is the period immediately following the third sub-period PA3. During sub-period PB1, the control unit 2 may set the power level of the bias RF signal to a first power level. Also, during sub-period PB1, the control unit 2 may control the first DC generation 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. The voltage level of the bias DC signal, i.e., the voltage level of the voltage pulse constituting the bias DC signal, increases as the energy of ions attracted to the substrate W by the voltage pulse applied to the lower electrode increases. Therefore, if the voltage pulse is a negative voltage, the voltage level of the voltage pulse increases as the absolute value of the voltage pulse increases.

[0072] The sub-period PB2 is the period following the sub-period PB1. When the cycle CY is repeated, the sub-period PB2 is the period immediately before the first sub-period PA1 of the subsequent first period PA. In the sub-period PB2, the control unit 2 may set the power level of the bias RF signal to a first power level. In the sub-period PB2, the control unit 2 may set the voltage level of the bias DC signal to a first voltage level. The ratio of the lengths of the periods included in the first period PA and the second period PB is adjusted as appropriate.

[0073] Step ST3 of the method MT will be described with reference to the timing chart of Figure 8, taking as an example a case where step ST3 is applied to a substrate W using the plasma processing apparatus 1 of the above embodiment. In the following description, further reference will be made to Figures 6 to 7 and Figures 9 to 11. Figures 9 to 11 are cross-sectional views of an example substrate related to a substrate processing method according to one exemplary embodiment.

[0074] 6 , in the first sub-period PA1 of the first period PA, the deposit DPF is deposited on the substrate W as a deposit DP. The deposit DPF contains fluorocarbon. In the first sub-period PA1, chemical species containing fluorocarbon are supplied from the plasma to the first region R1 and the second region R2, so that the deposit DPF is deposited on the upper surface of the first region R1 and the upper surface of the second region R2.

[0075] The deposit DPF may be preferentially formed on the first region R1 compared to the second region R2. Here, "the deposit DPF may be preferentially formed on the first region R1 compared to the second region R2" means, for example, that the thickness of the deposit DPF on the first region R1 is greater than the thickness of the deposit DPF on the second region R2.

[0076] After the first sub-period PA1 ends, in the second sub-period PA2, a bias RF signal is supplied to the substrate support 11. As a result, ions from the plasma collide with the deposit DPF, etching a portion of the deposit DPF. The etched deposit DPF adheres to the shoulder portion SH of the first region R1 as deposit DPC, as shown in FIG.

[0077] Furthermore, in the second sub-period PA2, ions from the plasma collide with the deposit DPF, thereby reducing the fluorine concentration in the deposit DPF and modifying the deposit DPF into a deposit DPC having a high carbon concentration. Without being bound by theory, the reason for this is believed to be as follows: ions whose energy has been adjusted by the supply of the bias RF signal collide with the deposit DP, causing fluorine to separate from the fluorocarbon. As a result, the fluorine concentration in the deposit DPF decreases. As shown in FIG. 9, the carbon concentration of the deposit DPF shown in FIG. 6 increases relatively, and the deposit DPC is transformed into a deposit DPC that is harder than the deposit DPF.

[0078] After the second sub-period PA2 ends, in a third sub-period PA3, the deposit DPF is deposited on the substrate W. In the third sub-period PA3, chemical species including fluorocarbons may be supplied from the plasma to the deposit DPC, thereby depositing the deposit DPF on the deposit DPC.

[0079] During the sub-period PB1 of the second period PB, while the power level of the source RF signal is reduced, a bias DC signal is supplied to the substrate support 11, thereby performing afterglow etching. Here, the bias signal determines the energy of ions supplied to the substrate W. In the case of the bias DC signal, the voltage level of the voltage pulse changes in a rectangular shape, resulting in a constant voltage level. This results in less ion energy variation and a higher perpendicularity of the ion propagation direction to the substrate W relative to the substrate W compared to the bias RF signal. Therefore, the etching is more perpendicular. During the sub-period PB1 in which the bias DC signal is used, ions propagate vertically from the opening OP in the first region R1 toward the second region R2. As shown in FIG. 10 , the second region R2 exposed by the opening OP in the first region R1 is etched vertically. Furthermore, the ions propagate vertically from the opening OP in the first region R1 to the second region R2, thereby suppressing lateral etching of the first region R1 and the second region R2.

[0080] 10 , when processing is performed again in the second sub-period PA2 of the first period PA, ions from the plasma collide with the deposit DPF, etching a portion of the deposit DPF. The etched deposit DPF also adheres to the boundary between the first region R1 and the second region R2 as deposit DPC, as shown in FIG. 11 . Because the shoulder portion SH of the first region R1 and the boundary between the first region R1 and the second region R2 are protected by the deposit DPC, the shoulder portion SH and the boundary are prevented from being etched laterally in the subsequent sub-period PB1.

[0081] As described above, the method MT suppresses lateral etching of the first region R1 and the second region R2, thereby suppressing lateral expansion of the etched shape. Furthermore, it is possible to improve the verticality of the shape of the second region R2 formed by etching.

[0082] 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.

[0083] For example, in step ST3, the power supply 30 may be controlled according to a timing chart other than the timing chart shown in Fig. 8. Fig. 12 is another example of a timing chart showing temporal changes in the source radio frequency signal, the bias RF signal, and the bias DC signal in one step of an etching method according to an exemplary embodiment. The timing chart shown in Fig. 12 is applied to step ST3 of the method MT. The timing chart shown in Fig. 12 differs from the timing chart shown in Fig. 8 in that the first period PA further includes a fourth sub-period PA4.

[0084] As shown in FIG. 8 , 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 PA4. The fourth sub-period PA4 is the period immediately following the third sub-period PA3. During the fourth sub-period PA4, the control unit 2 may control the first DC generating unit 32a to supply a bias DC signal to the substrate support member 11 at the second voltage level described above. During the fourth sub-period PA4, the control unit 2 may set the power level of the bias RF signal to the first power level described above. Note that the sub-period PB1 follows the fourth sub-period PA4. Therefore, the bias DC signal continues to be supplied from the first DC generating unit 32a during the sub-period PB1 even after the end of the fourth sub-period PA4.

[0085] 12 shows an example in which the first period PA includes the first sub-period PA1, the second sub-period PA2, the third sub-period PA3, and the fourth sub-period PA4, but 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 PA4, and the fourth sub-period PA4 may appear immediately after the second sub-period PA2. In this case, deposition of the deposit DPF on the deposit DPC is suppressed in the third sub-period PA3.

[0086] Furthermore, for example, the method MT shown in FIG. 4 may be applied to other substrates. FIG. 13 is a partially enlarged cross-sectional view of another example substrate to which the method of FIG. 4 can be applied. As shown in FIG. 13, in one embodiment, the substrate WA 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.

[0087] 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 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.

[0088] 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.

[0089] The substrate WA 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.

[0090] The substrate WA 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.

[0091] The substrate WA 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.

[0092] The method MT will be described below by taking as an example the case where the method MT is applied to a substrate WA using the plasma processing apparatus 1 of the above embodiment. In the following description, reference will be made to FIGS. 14 to 16 in addition to FIG. 13. Each of FIGS. 14 to 16 is a cross-sectional view of another example substrate related to a substrate processing method according to one illustrative embodiment. When the plasma processing apparatus 1 is used, the method MT can be performed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 by the control unit 2. In the method MT, the substrate WA is placed on a substrate support 11 (substrate support) and processed. Hereinafter, in the method MT applied to the substrate WA, descriptions of processes that are the same as those applied to the substrate W will be omitted as appropriate.

[0093] In step ST1, a substrate W shown in Fig. 13 is prepared. The substrate WA is transferred into the plasma processing chamber 10 by a transfer device (not shown). The substrate WA can be supported by a substrate support 11 in the plasma processing chamber 10. The substrate WA may have the shape shown in Fig. 12 as a result of plasma etching, or may have the shape shown in Fig. 12 from the time it is initially provided to the plasma processing chamber 10.

[0094] Subsequently, in step ST2, the controller 2 controls the gas supply unit 20 to supply a processing gas into the plasma processing chamber 10.

[0095] The subsequent process ST3 is performed while process ST2 is being performed. In process ST3, the control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to form deposits DP on the first region R1 and the second region R2 using plasma generated from the processing gas. Note that the timing chart for process ST3 may be the timing chart of FIG. 8 , but the following description of process ST3 will be given taking the case where the timing chart of FIG. 12 is used in process ST3 as an example.

[0096] In step ST3, first, as shown in FIG. 14 , the control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to etch the second region R2 so as to expose the first region R1. The second region R2 may be etched so as to expose the shoulder portion SH in the recess R1a of the first region R1. This etching may be the same as the processing described above in the fourth sub-period PA4 of the first period PA and the sub-period PB1 of the second period PB. Note that, as long as plasma is generated in the plasma processing space 10s, the processing in the sub-period PB1 of the second period PB may be performed to etch the second region R2.

[0097] Next, in step ST3, the above-described process in the first sub-period PA1 of the first period PA is performed, and deposits DP are formed on the upper surfaces of the first region R1 and the second region R2. Next, in step ST3, the above-described process in the second sub-period PA2 is performed, and some of the etched deposits DP are redeposited on the shoulder portions SH of the first region R1 (see FIG. 15 ). After the second sub-period PA2 ends, deposits DP can further accumulate on the substrate WA due to the above-described process in the third sub-period PA3.

[0098] Then, in step ST3, the second region R2 is further etched by the above-described processing in the fourth sub-period PA4 of the first period PA and the sub-period PB1 of the second period PB. During this etching, the shoulder portion SH is protected by the deposit DP, so lateral expansion of the etching shape at the shoulder portion SH is suppressed. Furthermore, as described above, a bias DC signal is supplied to the substrate support portion 11 during the fourth sub-period PA4 of the first period PA and the sub-period PB1 of the second period PB. Therefore, as described above, the second region R2 is etched in the vertical direction, suppressing lateral expansion of the etching shape.

[0099] Subsequently, 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 is terminated. If it is determined that the stop condition is not satisfied, the process returns to step ST3. The stop condition may include, for example, that the second region R2 in the recess R1a of the first region R1 is removed down to the underlying region UR, as shown in FIG. 16. In one embodiment, step ST3 is repeated until the stop condition is satisfied. In this embodiment, the control unit 2 repeatedly executes the control sequence to repeat step ST3.

[0100] Although the example in which step ST3 starts in the fourth sub-period PA4 and sub-period PB1 of the first period PA as the etching for exposing the shoulder portion SH has been described, another etching process for exposing the shoulder portion SH may be performed before step ST3. In this case, the control unit 2 may control the gas supply unit 20 and the plasma generation unit 12 so that step ST3 starts in the first sub-period PA1 of the first period PA. In this other etching process, the shoulder portion SH is exposed using plasma generated from the same processing gas as the processing gas used in step ST2.

[0101] Furthermore, in order to expose the shoulder portion SH before step ST3, the control unit 2 may control the gas supply unit 20 to supply another process gas containing a gas different from the above-described process gas into the plasma processing chamber 10 before step ST2. The other process gas contains carbon and fluorine, similar to the above-described process gas. The other process gas may further contain 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, similar to the above-described process gas. The other process gas may contain a noble gas, similar to the above-described process gas. The above-described process gas may contain hydrogen (H ２ ) gas, carbon monoxide (CO) gas and methane (CH ４ ) gases, another process gas may contain hydrogen (H ２ ) gas, carbon monoxide (CO) gas and methane (CH ４ ) gases containing gas species different from the above-mentioned process gases.

[0102] In this case, while another process gas is being supplied into the plasma processing chamber 10, the control unit 2 performs an etching process to expose the shoulder portion SH using plasma generated from the other process gas. The second region R2 may be etched so that the shoulder portion SH is exposed in the recess R1a of the first region R1. This etching may be the same as the process described above in the fourth sub-period PA4 of the first period PA and the sub-period PB1 of the second period PB. After this etching process is completed, the control unit 2 may control the gas supply unit 20 and the plasma generation unit 12 to perform step ST2 and start step ST3 in the first sub-period PA1 of the first period PA.

[0103] Hereinafter, with reference to Fig. 17 , 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. Fig. 17 is a diagram for explaining a plasma processing apparatus according to another exemplary embodiment. The plasma processing apparatus 1A according to the exemplary embodiment shown in Fig. 17 differs from the plasma processing apparatus 1 in that it includes a first insulating member 41A and a third insulating member 44. In other words, the plasma processing apparatus 1A differs in that it does not include the second insulating portion 47 of the first insulating member 41.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E19] below.

[0108] [E1] A method for manufacturing a semiconductor device, 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 carbon and fluorine 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 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 periods 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 a portion of the first period, supplying a bias radio frequency signal to the substrate support having a second frequency lower than the first frequency to attract ions from the plasma to the substrate support; and (c4) and applying a sequence of voltage pulses to the substrate support, the voltage pulses having a third frequency different from the first frequency and the second frequency, to draw ions from the plasma to the substrate support during at least a portion of the second period.

[0109] [E2] The etching method described in [E1], wherein the first period includes: a first sub-period in which the bias radio frequency signal and the sequence of voltage pulses are not supplied to the substrate support portion; a second sub-period in which the bias radio frequency signal is supplied to the substrate support portion after the first sub-period and the sequence of voltage pulses is not supplied to the substrate support portion; and a third sub-period in which the bias radio frequency signal and the sequence of voltage pulses are not supplied to the substrate support portion after the second sub-period.

[0110] [E3] The etching method according to [E2], wherein in (c1), during the first period, a deposit is formed on the first region and / or the second region using plasma generated from the processing gas, and in (c4), a portion of the deposit is removed by ions generated from the processing gas.

[0111] [E4] The etching method described in [E1], wherein the first period includes: a first sub-period in which the bias radio frequency signal and the sequence of voltage pulses are not supplied to the substrate support portion; a second sub-period after the first sub-period in which the bias radio frequency signal is supplied to the substrate support portion and the sequence of voltage pulses is not supplied to the substrate support portion; and a further sub-period after the second sub-period in which the bias radio frequency signal is not supplied to the substrate support portion and the sequence of voltage pulses is supplied to the substrate support portion.

[0112] [E5] The etching method according to [E4], wherein in (c1), during the first period excluding the fourth sub-period, a deposit is formed on the first region and / or the second region using plasma generated from the processing gas, and in (c4), a portion of the deposit is removed by sputtering of ions generated from the processing gas.

[0113] [E6] The etching method according to any one of [E1] to [E5], wherein in (a), the first region has a recess, and the recess is filled with the second region.

[0114] [E7] The etching method according to [E6], wherein in (a), the second region covers the first region, and the etching method further comprises: (d) supplying the process gas or another process gas containing carbon and fluorine into the chamber; and (e) while (d) is being performed and before (c) is being performed, etching a part of the second region using plasma generated from the process gas or the other process gas to expose the first region.

[0115] [E8] The etching method according to any one of [E1] to [E5], wherein the first region is provided on the second region and includes at least one opening.

[0116] [E9] The etching method according to any one of [E1] to [E8], 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.

[0117] [E10] The etching method according to any one of [E1] to [E9], wherein in (c2), the supply of the source radio frequency signal is stopped, or the power level of the source radio frequency signal is set to more than 0 W and not more than 50 W.

[0118] [E11] The etching method according to any one of [E1] to [E10], wherein in (c3), the bias high frequency signal is supplied having the second 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.

[0119] [E12] The etching method according to any one of [E1] to [E11], wherein in (c4), the sequence of voltage pulses is supplied having an absolute value of 100 V or more and 2000 V or less at the third frequency of 100 kHz or more and 800 kHz or less.

[0120] [E13] The etching method according to any one of [E1] to [E12], 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.

[0121] [E14] The etching method according to any one of [E1] to [E13], wherein the processing gas further contains an oxygen-containing gas and a noble gas.

[0122] [E15] The etching method according to any one of [E1] to [E14], wherein the processing gas further 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.

[0123] a first high frequency power supply configured to supply a source high frequency signal having a first frequency to generate plasma from the gas; a second high frequency power supply configured to supply a bias high frequency signal having a second frequency lower than the first frequency to the substrate support to attract ions from the plasma to the substrate support; a DC power supply configured to apply a DC voltage to the substrate support; and a control unit configured to control the gas supply unit, the first high frequency power supply, the second high 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 control unit is configured to: (a) prepare a substrate on the substrate support in the chamber, the substrate including a first region containing silicon and nitrogen and a second region containing silicon and oxygen; (b) supply a process gas containing carbon and fluorine into the chamber; (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 etch the second region, wherein (c) comprises: (c1) during a first time period, supplying a source radio frequency signal having a first frequency from the first radio frequency power supply 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 a portion of the first time period, supplying a bias radio frequency signal having a second frequency lower than the first frequency from the second radio frequency power supply to the substrate support to attract ions from the plasma to the substrate support.(c4) applying a sequence of voltage pulses from the DC power supply to the substrate support, the voltage pulses having a third frequency different from the first frequency and the second frequency, during at least a portion of the second period to attract ions from the plasma to the substrate support.

[0124] [E17] The plasma processing apparatus described in [E16] 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.

[0125] 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.

[0126] 1...plasma processing apparatus, 2...controller, 10...plasma processing chamber, 10a...side wall, 10s...plasma processing space, 11...substrate support, 12...plasma generation section, 13...shower head, 13d...upper electrode, 13e...top plate, 13f...first support, 14...top section, 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, DPC, DPF...deposit, W...substrate.

Claims

1. (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 carbon and fluorine 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 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 periods 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 during the first period; (c3) during a portion of the first period, supplying a bias radio frequency signal to the substrate support having a second frequency lower than the first frequency to attract ions from the plasma to the substrate support; and (c4) and applying a sequence of voltage pulses to the substrate support, the voltage pulses having a third frequency different from the first frequency and the second frequency, to draw ions from the plasma to the substrate support during at least a portion of the second period.

2. The etching method of claim 1, wherein the first period includes: a first sub-period in which the bias radio frequency signal and the sequence of voltage pulses are not supplied to the substrate support; a second sub-period after the first sub-period in which the bias radio frequency signal is supplied to the substrate support and the sequence of voltage pulses is not supplied to the substrate support; and a third sub-period after the second sub-period in which the bias radio frequency signal and the sequence of voltage pulses are not supplied to the substrate support.

3. The etching method according to claim 2, wherein in (c1), a deposit is formed on the first region and / or the second region using plasma generated from the processing gas during the first period, and in (c4), a portion of the deposit is removed by ions generated from the processing gas.

4. The etching method of claim 1, wherein the first period includes: a first sub-period in which the bias radio frequency signal and the sequence of voltage pulses are not supplied to the substrate support; a second sub-period after the first sub-period in which the bias radio frequency signal is supplied to the substrate support and the sequence of voltage pulses is not supplied to the substrate support; and a further sub-period after the second sub-period in which the bias radio frequency signal is not supplied to the substrate support and the sequence of voltage pulses is supplied to the substrate support.

5. The etching method according to claim 4, wherein in (c1), a deposit is formed on the first region and / or the second region using plasma generated from the processing gas during the first period excluding the further sub-period, and in (c4), a portion of the deposit is removed by ions generated from the processing gas.

6. The etching method according to any one of claims 1 to 5, wherein in (a), the first region has a recess, and the recess is filled with the second region.

7. The etching method according to claim 6, wherein in (a), the second region covers the first region, and the etching method further comprises: (d) supplying the process gas or another process gas containing carbon and fluorine into the chamber; and (e) while (d) is being performed and before (c) is being performed, etching a portion of the second region using plasma generated from the process gas or the other process gas to expose the first region.

8. The etching method according to any one of claims 1 to 5, wherein the first region is provided on the second region and includes at least one opening.

9. The etching method according to any one of claims 1 to 5, 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.

10. The etching method according to any one of claims 1 to 5, 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.

11. The etching method according to any one of claims 1 to 5, wherein in (c3), the bias high frequency signal is supplied having the second 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.

12. The etching method according to any one of claims 1 to 5, wherein in (c4), the sequence of voltage pulses having an absolute value of 100 V or more and 2000 V or less at the third frequency of 100 kHz or more and 800 kHz or less is supplied.

13. An etching method according to any one of claims 1 to 5, 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.

14. The etching method according to any one of claims 1 to 5, wherein the process gas further comprises an oxygen-containing gas and a noble gas.

15. The etching method according to any one of claims 1 to 5, wherein the process gas further comprises 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.

16. 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 provided in the chamber and configured to support a substrate; a first radio frequency power supply configured to supply a source radio frequency signal having a first frequency to generate plasma from the gas; a second radio frequency power supply configured to supply a bias radio frequency signal having a second frequency lower than the first frequency to the substrate support to attract ions from the plasma to the substrate support; a DC power supply configured to apply a DC voltage to the substrate support; and a controller configured to control the gas supply unit, the first radio frequency power supply, the second 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: (a) prepare a substrate on the substrate support in the chamber, the substrate including a first region containing silicon and nitrogen and a second region containing silicon and oxygen; (b) supply a process gas containing carbon and fluorine into the chamber; (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 etch the second region, wherein (c) comprises: (c1) during a first time period, supplying a source radio frequency signal having a first frequency from the first radio frequency power supply 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 a portion of the first time period, supplying a bias radio frequency signal having a second frequency lower than the first frequency from the second radio frequency power supply to the substrate support to attract ions from the plasma to the substrate support.(c4) applying a sequence of voltage pulses from the DC power supply to the substrate support, the voltage pulses having a third frequency different from the first frequency and the second frequency, during at least a portion of the second period to attract ions from the plasma to the substrate support.

17. The plasma processing apparatus described in claim 16, 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 which is part of the ceiling and is 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, is formed from a silicon-containing material, and extends from the periphery of the upper electrode to the chamber.

Images