Etching method and plasma treatment device

Abstract

In one exemplary embodiment, this etching method includes: (a) a step for providing a substrate on a substrate support in a chamber, the substrate including a first film and a second film having an opening on the first film, the first film containing a metal element and a non-metal element; and (b) a step for exposing the substrate to first plasma generated from a first processing gas containing halogen, phosphorus, and oxygen to form a recess in the first film.

Description

Etching method and plasma processing apparatus

[0001] Exemplary embodiments of this disclosure relate to etching methods and plasma processing apparatus.

[0002] In the manufacturing of electronic devices, plasma etching is sometimes performed on a film to form recesses. To create such recesses, a mask is formed on the film to be etched. A resist mask is known as such. The resist mask is consumed during the plasma etching of the film to be etched. Therefore, hard masks have been used. As for hard masks, a hard mask made of tungsten silicide (WSi) is known, as described in Patent Document 1.

[0003] Japanese Patent Publication No. 2007-294836

[0004] This disclosure provides a technology for etching films at a high etching rate.

[0005] In one exemplary embodiment, the etching method includes (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising metallic and nonmetallic elements, and (b) exposing the substrate to a first plasma generated from a first processing gas comprising chlorine, phosphorus, and oxygen to form recesses in the first film.

[0006] According to one exemplary embodiment, a technique for etching a film at a high etching rate is provided.

[0007] Figure 1 is a diagram illustrating an example configuration of a plasma processing system. Figure 2 is a diagram illustrating an example configuration of an inductively coupled plasma processing apparatus. Figure 3 is a flowchart of an etching method according to one exemplary embodiment. Figure 4 is a cross-sectional view of an example substrate to which the method of Figure 3 may be applied. Figure 5 is a cross-sectional view showing one step of the etching method according to one exemplary embodiment. Figure 6 is a cross-sectional view showing one step of the etching method according to one exemplary embodiment. Figure 7 is a cross-sectional view showing one step of the etching method according to one exemplary embodiment. Figure 8 is an example of a timing chart showing the time variation of source power and gas flow rate.

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts will be denoted by the same reference numerals.

[0009] Figure 1 is a diagram illustrating an example 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 unit 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 processing gas to the plasma processing space, and at least one gas outlet for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20, which will be described later, and the gas outlet is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is located in the plasma processing space and has a substrate support surface for supporting a substrate.

[0010] The plasma generation unit 12 is configured to generate plasma from at least one processing 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), ECR (Electron Cyclotron Resonance) plasma, helicon wave excited plasma (HWP), or surface wave plasma (SWP), etc. Various types of plasma generation units, including AC (Alternating Current) plasma generation units and DC (Direct Current) plasma generation units, may also be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. 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 the various processes described herein. The control unit 2 may be configured to control the elements of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 is implemented, for example, by a computer 2a. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The functions realized by the processing unit 2a1 described herein may be implemented in a circuit or processing circuit, including a general-purpose processor, an application-specific processor, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (Central Processing Unit), a conventional circuit, and / or a combination thereof, programmed to realize the described functions. The processor is considered to be a circuit or processing circuit, including transistors and other circuits. The processor may be a programmed processor that executes a program stored in the storage unit 2a2. This program may be pre-stored in the storage unit 2a2 or retrieved via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).In this disclosure, circuits, units, and means are hardware programmed to perform or configured to perform the functions described. Such hardware may be any hardware described in this disclosure, or any hardware known to be programmed to perform or execute the functions described. If such hardware is a processor that is considered to be a type of circuit, such circuit, means, or unit is a combination of hardware and software used to constitute such hardware and / or processor.

[0012] The following describes an example configuration of an inductively coupled plasma processing apparatus as an example of a plasma processing apparatus 1. Figure 2 is a diagram illustrating an example configuration of an inductively coupled plasma processing apparatus.

[0013] The inductively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply system 30, and an exhaust system 40. The plasma processing chamber 10 includes a dielectric window 101. The plasma processing apparatus 1 also includes a substrate support unit 11, a gas introduction unit, and an antenna 14. The substrate support unit 11 is located inside the plasma processing chamber 10. The antenna 14 is located on or above the plasma processing chamber 10 (i.e., on or above the dielectric window 101). The plasma processing chamber 10 has a plasma processing space 10s defined by the dielectric window 101, the side walls 102 of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded.

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

[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 bias electrode. The electrostatic chuck 1111 is placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic chuck electrode 1111b placed within the ceramic member 1111a. The electrostatic chuck electrode 1111b is also called a clamping electrode. In one embodiment, the electrostatic chuck electrode 1111b is electrically connected or coupled to a chuck power supply. The chuck power supply may be a DC power supply or an AC power supply. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Furthermore, other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have an annular region 111b. In this case, the ring assembly 112 may be placed on the annular electrostatic chuck or the annular insulating member, or on both the electrostatic chuck 1111 and the annular insulating member. Also, at least one bias electrode, electrically connected or coupled to the power supply 31 and / or power supply 32 described later, may be placed inside the ceramic member 1111a. Furthermore, the conductive member of the base 1110 and the bias electrode inside the ceramic member 1111a may function as multiple bias electrodes. Also, the electrostatic chuck electrode 1111b may function as a bias electrode. Therefore, the substrate support portion 11 includes at least one bias 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 covering ring. The edge rings are formed of a conductive or insulating material, and the covering rings are formed of an insulating material.

[0017] The substrate support section 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are arranged within the ceramic member 1111a of the electrostatic chuck 1111. The substrate support section 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0018] The gas introduction section is configured to introduce at least one processing gas from the gas supply section 20 into the plasma processing space 10s. In one embodiment, the gas introduction section includes a central gas injector (CGI) 13. The central gas injector 13 is located above the substrate support section 11 and is attached to a central opening formed in the dielectric window 101. The central gas injector 13 has at least one gas supply port 13a, at least one gas flow path 13b, and at least one gas inlet 13c. The processing gas supplied to the gas supply port 13a passes through the gas flow path 13b and is introduced into the plasma processing space 10s from the gas inlet 13c. In addition to or instead of the central gas injector 13, the gas introduction section may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 102.

[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 processing gas to the gas inlet from a corresponding gas source 21 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 at least one processing gas.

[0020] The power supply system 30 includes a power supply 31 that is electrically connected to or coupled to the plasma processing chamber 10. In one embodiment, the power supply 31 is electrically connected to or coupled to the plasma processing chamber 10 via at least one impedance matcher. The impedance matcher may be a mechanically controlled matcher or an electronically controlled matcher. The power supply 31 is configured to supply at least one RF signal (RF power) to at least one bias electrode and antenna 14. This generates plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the power supply 31 can function as at least part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to at least one bias electrode, a bias potential is generated on the substrate W, and ions in the formed plasma can be drawn into the substrate W.

[0021] The power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is electrically connected to or coupled to the antenna 14 and is configured to generate a source RF signal (source RF power) to generate plasma in the plasma processing space 10s. In one embodiment, the first RF generation unit 31a is electrically connected to or coupled to the antenna 14 via at least one impedance matcher. 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 generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. One or more generated source RF signals are supplied to the antenna 14.

[0022] The second RF generation unit 31b is electrically connected to or coupled to at least one bias electrode and is configured to generate a bias RF signal (bias RF power). In one embodiment, the second RF generation unit 31b is electrically connected to or coupled to at least one bias electrode via at least one impedance matcher. 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 generation unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one bias electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0023] The power supply system 30 may also include a power supply 32 that is electrically connected to or coupled to the plasma processing chamber 10. The power supply 32 includes a voltage generation unit 32a. In one embodiment, the voltage generation unit 32a is electrically connected to or coupled to at least one bias electrode and is configured to generate a voltage signal. The generated voltage signal is applied to at least one bias electrode.

[0024] In various embodiments, the voltage signal may be pulsed. In this case, the voltage generation unit 32a functions as a voltage pulse generation unit configured to generate a sequence of voltage pulses. Thus, the sequence of voltage pulses is applied to at least one bias electrode. In one embodiment, the sequence of voltage pulses has multiple cycles, each cycle including a burst of voltage pulses in a first period and a constant reference voltage in a second period. That is, the burst of voltage pulses is repeated in the sequence of voltage pulses. The absolute value of the voltage level of the voltage pulse is greater than the absolute value of the voltage level of the reference voltage. The voltage pulse may have an arbitrary waveform having a rectangular, trapezoidal, triangular, or a combination thereof, and the arbitrary waveform may change over time. The voltage pulse may have positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. Note that the voltage generation unit 32a may be provided in addition to the power supply 31, or it may be provided in place of the second RF generation unit 31b.

[0025] The antenna 14 includes one or more coils. In one embodiment, the antenna 14 may include an outer coil and an inner coil arranged coaxially. In this case, the power supply 31 may be connected to both the outer coil and the inner coil, or to either the outer coil or the inner coil. In the former case, the same RF generation unit may be connected to both the outer coil and the inner coil, or separate RF generation units may be connected to the outer coil and the inner coil separately.

[0026] The exhaust system 40 may be connected to, for example, a gas outlet 10e located 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 regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0027] FIG. 3 is a flowchart of an etching method according to one exemplary embodiment. The etching method MT1 shown in FIG. 3 (hereinafter referred to as "method MT1") can be executed by the plasma processing apparatus 1 of the above embodiment. The method MT1 can be applied to the substrate W.

[0028] FIG. 4 is a cross-sectional view of a substrate in an example to which the method of FIG. 3 can be applied. As shown in FIG. 4, in one embodiment, the substrate W includes a first film F1 and a second film F2 on the first film F1. The substrate W may further include a third film F3 under the first film F1. The substrate W may further include a base region UR under the third film F3.

[0029] The first film F1 may contain a metal element and a non-metal element. The first film F1 may contain at least one transition metal element selected from the group consisting of tungsten, titanium, molybdenum, hafnium, zirconium, and ruthenium as the metal element. The first film F1 may contain at least one selected from the group consisting of silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus as the non-metal element. The first film F1 may contain tungsten and at least one non-metal element selected from the group consisting of silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus. The first film F1 is tungsten silicide (W ｘ Si ｙ ), tungsten silicon nitride (W ｘ Si ｙ N ｚ１ ), tungsten silicon boride (W ｘ Si ｙ B ｚ２ ), tungsten silicon carbide (W ｘ Si ｙ C ｚ３ ), tungsten carbide (W ｘ C ｚ３ ), tungsten carbonitride (W ｘ C ｚ３ N ｚ１ ]>), and tungsten silicon carbonitride (W ｘ Si ｙ C ｚ３ N ｚ１The first film F1 may contain at least one tungsten compound selected from the group consisting of ). The first film F1 may contain tungsten and carbon, for example, tungsten silicon carbide (W ｘ Si ｙ C ｚ３ ), tungsten carbide (W ｘ C ｚ３ ), tungsten carbonitride (W ｘ C ｚ３ N ｚ１ ) and tungsten silicon carbonite (W ｘ Si ｙ C ｚ３ N ｚ１ It may contain at least one tungsten compound selected from the group consisting of ). The composition ratios x, y, z1, z2, and z3 may each be a real number greater than 0. The first film F1 may be a film for forming a hard mask.

[0030] The first film F1 may include at least one selected from the group consisting of metal-containing films and polysilicon films. The metal-containing film may contain the above-mentioned metal element but may not contain the above-mentioned non-metal element.

[0031] The second film F2 has an aperture OP. The second film F2 may have a plurality of apertures OP. The apertures OP may have a hole pattern or a line pattern. The dimensions (CD: Critical Dimension) of the apertures OP may be 200 nm or less, 100 nm or less, 30 nm or less, or 60 nm or more and 80 nm or less. The second film F2 may be a mask. The second film F2 may contain at least one selected from the group consisting of silicon-containing films, carbon-containing films, and metal-containing films. The metal-containing film included in the second film F2 may contain a different metal element than the metal element included in the first film F1. The second film F2 may contain at least one selected from the group consisting of silicon oxide films, resist films, and tin-containing films. The second film F2 may be a tin-containing photoresist mask. The second film F2 may be a resist mask for EUV exposure.

[0032] The third film F3 may be a silicon-containing film or a nitride film. The silicon-containing film may be a silicon nitride film (SiN film) or a silicon carbonitride film (SiCN film). The third film F3 may be an etching stop layer.

[0033] The base region UR may include, for example, at least one film for a memory device such as a DRAM or 3D-NAND.

[0034] The following describes method MT1, taking as an example the case where method MT1 is applied to the substrate W using the plasma processing apparatus 1 of the above embodiment, with reference to Figures 3 to 8. Figures 5 to 7 are cross-sectional views showing one step of an etching method according to one exemplary embodiment. When the plasma processing apparatus 1 is used, method MT1 can be executed in the plasma processing apparatus 1 by the control unit 2 controlling each part of the plasma processing apparatus 1. In method MT1, as shown in Figure 2, the substrate W on the substrate support part 11 arranged in the plasma processing chamber 10 is processed.

[0035] As shown in Figure 3, Method MT1 may include steps ST1 to ST4. Steps ST1 to ST4 may be performed in order. Steps ST1 to ST4 may be performed in situ. Method MT1 does not have to include at least one of steps ST3 and ST4.

[0036] (Step ST1) In step ST1, the substrate W shown in Figure 4 is placed on the substrate support portion 11 in the plasma processing chamber 10. The base region UR may be placed between the substrate support portion 11 and the third film F3.

[0037] (Step ST2) In step ST2, as shown in Figure 5, the substrate W is exposed to a first plasma PL1 generated from a first processing gas to form recesses RS in the first film F1. The recesses RS correspond to apertures OP. The first film F1 is etched by the first plasma PL1 through the apertures OP. The first plasma PL1 can be generated by supplying high-frequency power to the plasma processing apparatus 1. The high-frequency power may be a continuous wave or a pulse. The high-frequency power may also be source power.

[0038] The first process gas contains a halogen, phosphorus (P), and oxygen (O). The halogen may be chlorine (Cl) or bromine (Br). The first process gas may contain a halogen-containing gas, a phosphorus-containing gas, and an oxygen-containing gas. The halogen-containing gas may contain at least one selected from the group consisting of chlorine-containing gas and bromine-containing gas. The chlorine-containing gas is Cl ２ HCl, SiCl ２ SiCl ４ , CCl ４ , CLF ３ , BCl ３ , PCL ３ , PCL ５ and POCl ３ It may include at least one selected from the group consisting of HBr, CBr ２ F ２ , C ２ F ５ Br, PBr ３ , PBr ５ , POBr ３ and BrF ５ It may include at least one selected from the group consisting of the following. Phosphorus-containing gas is PF ３ , PF ５ , POF ３ HPF ６ , PCL ３ , PCL ５ , POCl ３ , PBr ３ , PBr ５ , POBr ３ PI ３ , P ４ O １０ , P ４ O ８ , P ４ O ６ PH ３ Ca ３ P ２ , H ３ PO ４ Na ３ PO ４ and C ３ H ９ It may contain at least one selected from the group consisting of P. Oxygen-containing gases are O ２ CO, CO２ , H ２ O, and H ２ O ２ may contain at least one selected from the group consisting of. The flow rate of the halogen-containing gas may be greater than the flow rate of each of the other gases contained in the first processing gas. The flow rate of the halogen-containing gas may be greater than the total flow rate of the phosphorus-containing gas and the oxygen-containing gas. The flow rate of the oxygen-containing gas may be greater than the flow rate of the phosphorus-containing gas.

[0039] The first processing gas may contain a halogen-containing gas containing phosphorus and oxygen (for example, POCl ３ ). The first processing gas may contain a halogen-containing gas containing phosphorus (for example, PCl ３ ) and an oxygen-containing gas (for example, O ２ ). The first processing gas may contain a halogen-containing gas (for example, Cl ２ ) and an oxygen-containing gas containing phosphorus (for example, P ４ O １０ ). The first processing gas may contain a phosphorus-containing gas (for example, PH ３ ) and a halogen-containing gas containing oxygen.

[0040] The first processing gas may further contain at least one selected from the group consisting of carbon and fluorine. The first processing gas may contain a fluorocarbon (C ｘ F ｙ ) gas. Each of x and y is a natural number. The first processing gas may contain CF ４ . The first processing gas may contain at least one selected from the group consisting of a carbon-containing gas and a fluorine-containing gas. The carbon-containing gas may not contain fluorine. The fluorine-containing gas may not contain carbon.

[0041] The first processing gas may further contain an inert gas. Examples of the inert gas include noble gases and nitrogen gas. Examples of the noble gas include argon gas.

[0042] In step ST2, the temperature of the substrate support portion 11 may be 0 °C or higher, or 50 °C or higher, or 100 °C or higher, or 250 °C or lower, or 300 °C or lower.

[0043] In step ST2, the pressure inside the plasma processing chamber 10 may be 4 Pa ​​(30 mTorr) or less.

[0044] In step ST2, bias power may be supplied to the substrate support portion 11. The bias power may be a continuous wave or a pulse.

[0045] (Step ST3) In step ST3, as shown in Figure 6, the substrate W is exposed to a second plasma PL2 generated from a second processing gas. The second plasma PL2 can be generated by supplying high-frequency power to the plasma processing apparatus 1. The high-frequency power may be a continuous wave or a pulse. The high-frequency power may also be source power.

[0046] The second process gas is different from the first process gas. The second process gas contains an oxygen-containing gas. The oxygen-containing gas contained in the second process gas may be the same as or different from the oxygen-containing gas contained in the first process gas of step ST2. An example of the oxygen-containing gas in step ST3 is the same as the example of the oxygen-containing gas in step ST2. The second process gas may further contain an inert gas. An example of the inert gas in step ST3 is the same as the example of the inert gas in step ST2.

[0047] The second plasma PL2 forms a modified region MR on the side wall RSa of the recess RS. The modified region MR may be an oxide layer. The modified region MR may contain oxides of metal elements contained in the first film F1, or it may contain oxides of nonmetal elements contained in the first film F1. The second plasma PL2 may also form a modified region MR on the bottom RSb of the recess RS.

[0048] In step ST3, the temperature of the substrate support portion 11 may be 50°C or higher, 100°C or higher, or 250°C or lower.

[0049] The pressure inside the plasma processing chamber 10 in step ST3 may be higher than the pressure inside the plasma processing chamber 10 in step ST2. The pressure inside the plasma processing chamber 10 in step ST3 may be 1.3 Pa (10 mTorr) or higher.

[0050] In step ST3, bias power does not have to be supplied to the substrate support 11, and bias power smaller than the bias power supplied to the substrate support 11 in step ST2 may be supplied to the substrate support 11. The bias power may be a continuous wave or a pulse.

[0051] The processing time for process ST3 may be shorter than the processing time for process ST2, or it may be less than or equal to half the processing time for process ST2, or it may be less than or equal to one-third of the processing time for process ST2.

[0052] (Step ST4) Step ST4 is a repetition of steps ST2 and ST3. The modified region MR on the side wall RSa of the recessed RS suppresses etching of the side wall RSa in step ST2 after step ST3. The modified region MR formed on the bottom RSb of the recessed RS is removed by etching in step ST2 after step ST3. Step ST4 may be carried out until the bottom RSb of the recessed RS reaches the third film F3, as shown in Figure 7. The aspect ratio of the recessed RS after step ST4 may be 5 or more, or 10 or more. The aspect ratio of the recessed RS is expressed as D1 / D2, where D1 is the depth of the recessed RS and D2 is the dimension of the recessed RS at the upper end of the recessed RS.

[0053] A purging step may be performed between step ST2 and step ST3 to purge the internal space of the plasma processing chamber 10.

[0054] After step ST4, the modified region MR of the side wall RSa of the recess RS may be removed, for example, by diluted hydrofluoric acid (DHF). This may increase the dimension (CD) of the recess RS.

[0055] Figure 8 is an example of a timing chart showing the time variation of source power and gas flow rate. This timing chart relates to processes ST2 and ST3. The vertical axis of Figure 8 represents the flow rate of the first process gas, the flow rate of the second process gas, and the source power. The horizontal axis of Figure 8 represents time.

[0056] As shown in Figure 8, during period PA corresponding to process ST2, a first process gas at a flow rate of FL1 is supplied. During period PA, the second process gas is not supplied. During period PB corresponding to process ST3, a second process gas at a flow rate of FL2 is supplied. During period PB, the first process gas is not supplied. During period PC, the purging process between process ST2 and process ST3, neither the first nor the second process gas is supplied. In process ST4, a cycle CY including periods PA, PB, and PC is repeated.

[0057] Period PA may include periods PA1, PA2, and PA3. Period PA2 is the period following period PA1. Period PA3 is the period following period PA2. Period PA1 is the period for stabilizing the flow rate of the first processing gas. Period PA2 is the period for igniting the first plasma PL1. Period PA3 is the period for etching the first film F1. In period PA1, source power is either not supplied or source power at level SL is supplied. In periods PA2 and PA3, source power at level SH, which is higher than level SL, is supplied. Period PA does not have to include at least one of periods PA1 and PA2.

[0058] Period PB may include period PB1 and period PB2. Period PB2 is the period following period PB1. Period PB1 is the period for stabilizing the flow rate of the second treatment gas. Period PB2 is the period for modifying the sidewall RSa of the recess RS of the first membrane F1. In period PB1, source power is either not supplied or source power at level SL is supplied. In period PB2, source power at level SH, which is higher than level SL, is supplied. Period PB does not have to include period PB1.

[0059] During period PC, source power is either not supplied or source power at level SL is supplied. Source power at level SH may be supplied during period PC and period PB1. That is, source power at level SH may be continuously supplied from period PA through period PC to period PB.

[0060] During period PA, bias power may be supplied to the substrate support section 11. During periods PB and PC, bias power may not be supplied to the substrate support section 11, or a bias power smaller than the bias power supplied during period PA may be supplied.

[0061] According to the plasma processing apparatus 1 and method MT1 described above, in step ST2, the first processing gas contains phosphorus and oxygen in addition to halogen, thereby improving the etching rate of the first film F1. It is presumed that the etching rate improves because the addition of phosphorus and oxygen increases the density of radicals that become etchants (e.g., halogen radicals), but the mechanism is not limited to this. The improved etching rate allows for a reduction in etching time, thus improving throughput. Furthermore, the etching selectivity ratio of the first film F1 to the second film F2 can also be improved. In addition, the thickness of the modified region MR after step ST4 can also be reduced. This is presumed to be due to the reduced number of times step ST2 is performed because the etching rate of the first film F1 is improved, but the mechanism is not limited to this.

[0062] The following describes various experiments conducted to evaluate Method MT1. The experiments described below are not intended to limit this disclosure.

[0063] (First Experiment) In the first experiment, a substrate having a WSiN film and a mask on the WSiN film was prepared (Step ST1). The mask was a silicon oxide film having openings. The WSiN film was etched with plasma generated from a first processing gas containing chlorine gas, phosphorus fluoride gas, oxygen gas, and argon gas (Step ST2).

[0064] (Experiment 2) The experiment was conducted in the same manner as in Experiment 1, except that oxygen gas was removed from the first treatment gas. The first treatment gas in this experiment contained chlorine gas, phosphorus fluoride gas, and argon gas.

[0065] (Third experiment) Remove phosphorus fluoride gas and oxygen gas from the first processing gas described above, and CF ４ The experiment was conducted in the same manner as the first experiment, except that gas was added. The first treatment gas in this experiment was chlorine gas and CF4.４ It contains gas and argon gas.

[0066] (Fourth experiment) Remove phosphorus fluoride gas from the first processing gas described above, and CF ４ The experiment was conducted in the same manner as the first experiment, except that gas was added. The first treatment gas in this experiment was chlorine gas and CF4. ４ It contains gas, oxygen gas, and argon gas.

[0067] (Results of Experiment 1) The etching rate of the WSiN film was calculated by measuring the depth of the recesses formed in the WSiN film in the cross-section of the substrates from Experiment 1 to Experiment 4. The etching rate in Experiment 1 was 0.65 nm / second. The etching rate in Experiment 2 was 0.37 nm / second. The etching rate in Experiment 3 was 0.31 nm / second. The etching rate in Experiment 4 was 0.40 nm / second. Therefore, it was suggested that using a processing gas containing halogen, phosphorus, and oxygen dramatically improved the etching rate of the WSiN film compared to using other processing gases.

[0068] In experiments 1 through 4, optical emission spectroscopy (OES) was performed. In experiment 1, the radical density (e.g., Cl, F) was higher compared to experiments 2 through 4.

[0069] (Experiment 5) In Experiment 5, after etching the WSiN film in the same manner as in Experiment 1, the substrate was exposed to a second plasma generated from a second processing gas containing oxygen gas and an inert gas to oxidize the side walls of the depressions formed in the WSiN film (Step ST3). The etching and oxidation cycle was repeated 20 times (Step ST4).

[0070] (Experiment 6) In Experiment 6, after etching the WSiN film in the same manner as in Experiment 3, the substrate was exposed to a second plasma generated from a second processing gas containing oxygen gas and an inert gas to oxidize the side walls of the depressions formed in the WSiN film. The etching and oxidation cycle was repeated 20 times.

[0071] (Results of Experiment 2) The etching rate of the WSiN film was calculated by measuring the depth of the recesses formed in the WSiN film in the cross-sections of the substrates from Experiments 5 and 6. The etching rate in Experiment 5 was 0.95 nm / second. The etching rate in Experiment 6 was 0.51 nm / second. Therefore, it was suggested that using a processing gas containing halogen, phosphorus, and oxygen dramatically improved the etching rate of the WSiN film compared to using other processing gases.

[0072] In the cross-sections of the substrates from Experiment 5 and Experiment 6, the etching selectivity ratio of the WSiN film to the mask was calculated by measuring the depth of the recesses formed in the WSiN film and the thickness of the mask. The etching selectivity ratio in Experiment 5 was 3.4. The etching selectivity ratio in Experiment 6 was 2.2. Therefore, it was suggested that using a processing gas containing halogen, phosphorus, and oxygen dramatically improved the etching selectivity ratio of the WSiN film to the mask compared to using other processing gases.

[0073] The Boeing CD was calculated by measuring the CD of the recesses formed in the WSiN film in the cross-sections of the substrates from Experiment 5 and Experiment 6. The Boeing CDs from Experiment 5 and Experiment 6 were almost identical.

[0074] (Experiment 7) In Experiment 7, the substrate obtained in the same manner as in Experiment 5 was exposed to diluted hydrofluoric acid to remove the oxide layer formed on the side walls of the recesses.

[0075] (Experiment 8) In Experiment 8, the substrate obtained in the same manner as in Experiment 6 was exposed to diluted hydrofluoric acid to remove the oxide layer formed on the side walls of the recesses. However, the number of cycles in Experiment 8 was increased so that the depth of the recesses after etching was about the same as in Experiment 7.

[0076] (Results of Experiment 3) In Experiment 7, the etching time was significantly reduced compared to Experiment 8.

[0077] In experiments 7 and 8, the cross-sections of the substrate were observed before and after diluted hydrofluoric acid treatment. The increase in Boeing CD was calculated by measuring the CD of the depressions formed in the WSiN film in the cross-section of the substrate. The increase in Boeing CD in experiment 7 was approximately 2 nm. The increase in Boeing CD in experiment 8 was approximately 4 nm. Therefore, it was suggested that using a treatment gas containing halogen, phosphorus, and oxygen dramatically reduces the increase in Boeing CD compared to using other treatment gases.

[0078] (Experiment 9) In Experiment 9, a substrate with a tungsten film was prepared. The tungsten film was etched by exposing the substrate to a first plasma generated from a first processing gas containing chlorine gas, phosphorus fluoride gas, oxygen gas, and argon gas.

[0079] (Experiment 10) Chlorine gas and CF ４ The experiment was conducted in the same manner as in Experiment 9, except that the first treatment gas, which included gas and argon gas, was used.

[0080] (Experiment 11) In Experiment 11, a substrate having a polysilicon film was prepared. The substrate was exposed to a first plasma generated from a first processing gas containing chlorine gas, phosphorus fluoride gas, oxygen gas, and argon gas, and the polysilicon film was etched.

[0081] (Experiment 12) Chlorine gas and CF ４ The experiment was conducted in the same manner as the 11th experiment, except that a first treatment gas containing gas and argon gas was used.

[0082] (Results of Experiment 4) The etching rate was calculated by measuring the amount of etching of the tungsten film and polysilicon film in the cross-section of the substrates from Experiments 9 to 12. The etching rate of the tungsten film in Experiment 9 was 1.35 times that of the tungsten film in Experiment 10. The etching rate of the polysilicon film in Experiment 11 was 1.45 times that of the polysilicon film in Experiment 12. Therefore, it was suggested that using a processing gas containing halogen, phosphorus, and oxygen dramatically improved the etching rate of the tungsten film and polysilicon film compared to using other processing gases.

[0083] From the above description, it will be understood that the various embodiments of this disclosure are described herein for illustrative purposes and can be modified in various ways without departing from the scope and spirit of this disclosure. Accordingly, the various embodiments disclosed herein are not intended to limit the scope and spirit, and the true scope and spirit are shown by the appended claims.

[0084] Herein, various exemplary embodiments included in this disclosure are described in [E1] to [E20] below.

[0085] [E1] An etching method comprising: (a) a step of providing a substrate on a substrate support portion in a chamber, wherein the substrate comprises a first film and a second film having an opening on the first film, and the first film contains metallic and nonmetallic elements; and (b) a step of exposing the substrate to a first plasma generated from a first processing gas containing chlorine, phosphorus and oxygen to form recesses in the first film.

[0086] [E2] (c) The etching method according to [E1], further comprising the step of exposing the substrate to a second plasma generated from a second processing gas containing an oxygen-containing gas.

[0087] [E3] (d) The etching method according to [E2], further comprising the step of repeating (b) and (c).

[0088] [E4] The etching method according to [E2] or [E3], wherein the pressure in the chamber in (c) is higher than the pressure in the chamber in (b).

[0089] [E5] The etching method according to any one of [E2] to [E4], wherein the processing time of (c) is shorter than the processing time of (b).

[0090] [E6] The etching method according to any one of [E1] to [E5], wherein the first film comprises at least one transition metal element selected from the group consisting of tungsten, titanium, molybdenum, hafnium, zirconium, and ruthenium as the metal element.

[0091] [E7] The etching method according to any one of [E1] to [E6], wherein the first film comprises at least one selected from the group consisting of silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus as the nonmetallic element.

[0092] [E8] The etching method according to [E7], wherein the first film comprises at least one tungsten compound selected from the group consisting of tungsten silicide, tungsten silicon nitride, tungsten silicon boride, tungsten silicon carbide, tungsten carbide, tungsten carbonitride, and tungsten silicon carbonitride.

[0093] [E9] The etching method according to any one of [E1] to [E8], wherein the dimensions of the opening are 200 nm or less.

[0094] [E10] The etching method according to any one of [E1] to [E9], wherein the second film is selected from the group consisting of a silicon-containing film, a carbon-containing film, and a metal-containing film containing a metal element different from the metal element contained in the first film.

[0095] [E11] The etching method according to [E10], wherein the second film comprises at least one selected from the group consisting of a silicon oxide film, a resist film, and a tin-containing film.

[0096] [E12] The first processing gas includes a chlorine-containing gas, a phosphorus-containing gas, and an oxygen-containing gas, and is the etching method according to any one of [E1] to [E11].

[0097] [E13] The chlorine-containing gas is Cl ２ , HCl, SiCl ２ , SiCl ４ , CCl ４ , ClF ３ , BCl ３ , PCl ３ , PCl ５ and POCl ３ and includes at least one selected from the group consisting of, and is the etching method according to [E12].

[0098] [E14] The phosphorus-containing gas is PF ３ , PF ５ , POF ３ , HPF ６ , PCl ３ , PCl ５ , POCl ３ , PBr ３ , PBr ５ , POBr ３ , PI ３ , P ４ O １０ , P ４ O ８ , P ４ O ６ , PH ３ , Ca ３ P ２ , H ３ PO ４ , Na ３ PO ４ and C ３ , H ９ P and includes at least one selected from the group consisting of, and is the etching method according to [E12] or [E13].

[0099] [E15] The oxygen-containing gas is O ２ , CO, CO ２ , H ２ O and H ２ O ２ and includes at least one selected from the group consisting of, and is the etching method according to any one of [E12] to [E14].

[0100] [E16] The etching method according to any one of [E1] to [E15], wherein the first processing gas further comprises at least one selected from the group consisting of carbon and fluorine.

[0101] [E17] The etching method according to [E16], wherein the first processing gas comprises a fluorocarbon gas.

[0102] [E18] The etching method according to any one of [E1] to [E17], wherein in (b) above, the temperature of the substrate support portion is 0°C or more and 300°C or less.

[0103] [E19] An etching method comprising: (a) a step of providing a substrate on a substrate support in a chamber, wherein the substrate comprises a first film and a second film having an opening on the first film, and the first film comprises a metallic element and a nonmetallic element; and (b) a step of exposing the substrate to a first plasma generated from a first processing gas comprising a halogen, phosphorus and oxygen to form a recess in the first film.

[0104] [E20] A plasma processing apparatus comprising: a chamber; a substrate support portion for supporting a substrate within the chamber, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising metallic and nonmetallic elements; a gas supply portion configured to supply a first processing gas into the chamber, the first processing gas comprising chlorine, phosphorus, and oxygen; a plasma generation portion configured to generate a first plasma from the first processing gas within the chamber; and a control portion, the control portion configured to control the gas supply portion and the plasma generation portion so as to expose the substrate to the first plasma and form a recess in the first film.

[0105] 1...Plasma processing apparatus, 2...Control unit, 10...Plasma processing chamber, 11...Substrate support unit, 12...Plasma generation unit, 20...Gas supply unit, F1...First film, F2...Second film, OP...Aperture, PL1...First plasma, RS...Recess, W...Substrate.

Claims

1. An etching method comprising: (a) a step of providing a substrate on a substrate support portion in a chamber, wherein the substrate comprises a first film and a second film having an opening on the first film, and the first film contains metallic and nonmetallic elements; and (b) a step of exposing the substrate to a first plasma generated from a first processing gas containing chlorine, phosphorus, and oxygen to form a recess in the first film.

2. (c) The etching method according to claim 1, further comprising the step of exposing the substrate to a second plasma generated from a second processing gas containing an oxygen-containing gas.

3. (d) The etching method according to claim 2, further comprising the step of repeating (b) and (c).

4. The etching method according to claim 2, wherein the pressure in the chamber in (c) is higher than the pressure in the chamber in (b).

5. The etching method according to claim 2, wherein the processing time in (c) is shorter than the processing time in (b).

6. The etching method according to any one of claims 1 to 5, wherein the first film comprises at least one transition metal element selected from the group consisting of tungsten, titanium, molybdenum, hafnium, zirconium, and ruthenium as the metal element.

7. The etching method according to any one of claims 1 to 5, wherein the first film comprises at least one selected from the group consisting of silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus as the nonmetallic element.

8. The etching method according to claim 7, wherein the first film comprises at least one tungsten compound selected from the group consisting of tungsten silicide, tungsten silicon nitride, tungsten silicon boride, tungsten silicon carbide, tungsten carbide, tungsten carbonitride, and tungsten silicon carbonitride.

9. The etching method according to any one of claims 1 to 5, wherein the dimensions of the aperture are 200 nm or less.

10. The etching method according to any one of claims 1 to 5, wherein the second film comprises at least one selected from the group consisting of a silicon-containing film, a carbon-containing film, and a metal-containing film containing a metal element different from the metal element contained in the first film.

11. The etching method according to claim 10, wherein the second film comprises at least one selected from the group consisting of a silicon oxide film, a resist film, and a tin-containing film.

12. The etching method according to any one of claims 1 to 5, wherein the first processing gas includes a chlorine-containing gas, a phosphorus-containing gas, and an oxygen-containing gas.

13. The chlorine-containing gas is Cl ２ , HCl, SiCl ２ , SiCl ４ , CCl ４ , ClF ３ , BCl ３ , PCl ３ , PCl ５ and POCl ３ The etching method according to claim 12, comprising at least one selected from the group consisting of 14. The phosphorus-containing gas is PF ３ , PF ５ , POF ３ HPF ６ , PCL ３ , PCL ５ , POCl ３ , PBr ３ , PBr ５ , POBr ３ PI ３ , P ４ O １０ , P ４ O ８ , P ４ O ６ PH ３ Ca ３ P ２ , H ３ PO ４ Na ３ PO ４ and C ３ H ９ The etching method according to claim 12, comprising at least one selected from the group consisting of P.

15. The oxygen-containing gas is O ２ CO, CO ２ , H ２ O and H ２ O ２ The etching method according to claim 12, comprising at least one selected from the group consisting of the following.

16. The etching method according to any one of claims 1 to 5, wherein the first processing gas further comprises at least one selected from the group consisting of carbon and fluorine.

17. The etching method according to claim 16, wherein the first processing gas includes a fluorocarbon gas.

18. The etching method according to any one of claims 1 to 5, wherein, in (b) above, the temperature of the substrate support portion is 0°C or higher and 300°C or lower.

19. An etching method comprising: (a) a step of providing a substrate on a substrate support portion in a chamber, wherein the substrate comprises a first film and a second film having an opening on the first film, and the first film comprises a metallic element and a nonmetallic element; and (b) a step of exposing the substrate to a first plasma generated from a first processing gas comprising a halogen, phosphorus and oxygen to form a recess in the first film.

20. A plasma processing apparatus comprising: a chamber; a substrate support portion for supporting a substrate within the chamber, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising metallic and nonmetallic elements; a gas supply portion configured to supply a first processing gas into the chamber, the first processing gas comprising chlorine, phosphorus, and oxygen; a plasma generation portion configured to generate a first plasma from the first processing gas within the chamber; and a control portion, the control portion configured to control the gas supply portion and the plasma generation portion so as to expose the substrate to the first plasma and form a recess in the first film.

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