Etching method and plasma processing apparatus

Abstract

Provided is a technique for suppressing the occurrence of shape abnormalities during etching of a silicon film. The etching method includes: a step (a) in which a substrate having a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film is provided on a substrate support portion disposed in a chamber; and (b) supplying a processing gas containing a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas into the chamber, and generating plasma from the processing gas to etch the silicon film or the silicon-containing conductive film.

Description

Technical Field

[0001] Exemplary embodiments of the present disclosure relate to an etching method and a plasma processing apparatus. Background Art

[0002] Patent Document 1 discloses a technique for etching a silicon-containing film.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: U.S. Patent Application Publication No. 2016 / 0343580 Summary of the Invention

[0006] Technical Problem to be Solved by the Invention

[0007] The present disclosure provides a technique for suppressing shape abnormalities generated during etching of a silicon film.

[0008] Technical Means for Solving the Problem

[0009] An etching method according to an exemplary embodiment of the present disclosure includes: step (a) of providing a substrate onto a substrate support portion disposed in a chamber, wherein the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; and step (b) of supplying a processing gas containing a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas into the chamber, and generating a plasma from the processing gas to etch the silicon film or the silicon-containing conductive film.

[0010] Advantageous Effects of the Invention

[0011] According to an exemplary embodiment of the present disclosure, a technique for suppressing shape abnormalities generated during etching of a silicon film can be provided. Brief Description of the Drawings

[0012] Figure 1 is a diagram for explaining a structural example of a plasma processing system.

[0013] Figure 2 is a diagram for explaining a structural example of a capacitively coupled plasma processing apparatus.

[0014] Figure 3 is a flowchart showing an example of an etching method.

[0015] Figure 4 is a diagram showing an example of a cross-sectional structure of a substrate W.

[0016] Figure 5 is a diagram showing an example of a cross-sectional structure of the substrate W during the process of step ST2.

[0017] Figure 6It is a graph showing the amount of F radicals generated when generating plasma using various gases.

[0018] Figure 7 It is a graph showing the etching results of a silicon film in the case where PF3 gas is used as part of the processing gas and in the case where NF3 gas is used. Detailed implementation manners

[0019] Hereinafter, each implementation manner of the present disclosure will be described.

[0020] In one exemplary implementation manner, an etching method is provided, including: step (a), providing a substrate onto a substrate support portion disposed in a chamber, where the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; and step (b), supplying a processing gas containing a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas into the chamber, and generating plasma from the processing gas to etch the silicon film or the silicon-containing conductive film.

[0021] In one exemplary implementation manner, the silicon-containing conductive film is a film containing silicon and containing germanium or a metal.

[0022] In one exemplary implementation manner, the mask includes at least one selected from a silicon-containing insulating film, a metal-containing film, and an organic film.

[0023] In one exemplary implementation manner, in step (b), the ratio of the flow rate of the phosphorus fluoride gas to the flow rate of the processing gas is changed.

[0024] In one exemplary implementation manner, step (b) includes: step (b1), etching the silicon film or the silicon-containing conductive film using a first plasma generated from a first processing gas, where the first processing gas contains the phosphorus fluoride gas at a first flow rate ratio; and step (b2), etching the silicon film or the silicon-containing conductive film using a second plasma generated from a second processing gas, where the second processing gas does not contain the phosphorus fluoride gas or contains the phosphorus fluoride gas at a second flow rate ratio less than the first flow rate ratio.

[0025] In one exemplary implementation manner, step (b2) is performed after step (b1).

[0026] In one exemplary implementation manner, step (b1) is performed after step (b2).

[0027] In one exemplary implementation manner, step (b1) and step (b2) are repeatedly performed multiple times.

[0028] In one exemplary implementation manner, the flow rate of the bromine-containing gas is greater than the flow rate of the phosphorus fluoride gas.

[0029] In an exemplary embodiment, the flow rate of the bromine-containing gas is 10% by volume or more and 99.9% by volume or less of the flow rate of the processing gas.

[0030] In an exemplary embodiment, the flow rate of the phosphorus fluoride gas is 0.1% by volume or more and 50% by volume or less of the flow rate of the processing gas.

[0031] In an exemplary embodiment, the ratio of the flow rate of the bromine-containing gas to the flow rate of the phosphorus fluoride gas is in the range of 1 to 999.

[0032] In an exemplary embodiment, the bromine-containing gas is at least any one of HBr gas and Br2 gas.

[0033] In an exemplary embodiment, the phosphorus fluoride gas is at least any one of PF3 gas and PF5 gas.

[0034] In an exemplary embodiment, the oxygen-containing gas is at least one selected from O2 gas, CO gas, and CO2 gas.

[0035] In an exemplary embodiment, there is provided an etching method including: step (a) of providing a substrate onto a substrate support portion disposed in a chamber, wherein the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; and step (b) of supplying a processing gas containing a first gas, a second gas, and an oxygen-containing gas into the chamber and generating a plasma from the processing gas to etch the silicon film or the silicon-containing conductive film, wherein the first gas contains a first halogen and the second gas contains a second halogen and phosphorus.

[0036] In an exemplary embodiment, the silicon-containing conductive film is a film containing silicon and containing germanium or a metal.

[0037] In an exemplary embodiment, in step (b), the ratio of the flow rate of the second gas to the flow rate of the processing gas is changed.

[0038] In an exemplary embodiment, the mask contains at least one selected from a silicon-containing insulating film, a metal-containing film, and an organic film.

[0039] In an exemplary embodiment, the mask contains at least one selected from silicon oxide, SiON, W, WSi, WSiN, WC, TiN, and TiO.

[0040] In an exemplary embodiment, the first gas is at least one selected from HBr gas, Br2 gas, and Cl2 gas.

[0041] In an exemplary embodiment, the second gas is at least one selected from PF3 gas, PF5 gas, and PCl3 gas.

[0042] In an exemplary embodiment, a plasma processing apparatus is provided, which includes a chamber, a substrate support portion disposed in the chamber, a plasma generation portion, and a control portion. Among them, the control portion performs:

[0043] Controlling (a), providing a substrate onto the substrate support portion, where the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; and

[0044] Controlling (b), supplying a processing gas containing a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas into the chamber, and generating plasma from the processing gas to etch the silicon film or the silicon-containing conductive film.

[0045] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, in each drawing, the same or similar elements are denoted by the same reference numerals, and repeated descriptions are omitted. Unless otherwise specified, the positional relationships such as up, down, left, and right are described based on the positional relationships shown in the drawings. The dimensional ratios of the drawings do not represent actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

[0046] <An example of a plasma processing system>

[0047] Figure 1 It is a diagram for explaining a structural example of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control portion 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 portion 11, and a plasma generation portion 12. The plasma processing chamber 10 has a plasma processing space. In addition, the plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas into the plasma processing space and at least one gas discharge port for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply portion 20 described later, and the gas discharge port is connected to an exhaust system 40 described later. The substrate support portion 11 is disposed in the plasma processing space and has a substrate support surface for supporting the substrate.

[0048] 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 plasma (Electron-Cyclotron-resonance plasma), helicon wave plasma (HWP), surface wave plasma (SWP), or the like. In addition, various types of plasma generation units including an AC (Alternating Current) plasma generation unit and a DC (Direct Current) plasma generation unit may 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.

[0049] The control unit 2 can process computer-executable commands for causing the plasma processing apparatus 1 to execute various steps described in the present disclosure. The control unit 2 can be configured to control the respective elements of the plasma processing apparatus 1 to execute the various steps 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, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 can be configured to execute various control actions by reading a program from the storage unit 2a2 and executing the read program. The program may be pre-stored in the storage unit 2a2 or may be obtained via a medium when needed. The obtained program is stored in the storage unit 2a2 and is read and executed by the processing unit 2a1 from the storage unit 2a2. The medium may be various storage media readable by the computer 2a or may be a communication line connected to the communication interface 2a3. The storage unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 can communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0050] Hereinafter, a structural example of an inductively coupled plasma processing apparatus as an example of the plasma processing apparatus 1 will be described. Figure 2 FIG. is a diagram for explaining a structural example of an inductively coupled plasma processing apparatus. The inductively 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 chamber 10 includes a dielectric window 101. In addition, the plasma processing apparatus 1 includes a substrate support portion 11, a gas introduction portion, and an antenna 14. The substrate support portion 11 is disposed inside the plasma processing chamber 10. The antenna 14 is disposed 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 wall 102 of the plasma processing chamber 10, and the substrate support portion 11. The plasma processing chamber 10 is grounded.

[0051] 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 the 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 top view. The substrate W is disposed on the central region 111a of the main body portion 111, and the ring assembly 112 is disposed 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. Accordingly, the central region 111a is also referred to as a substrate support surface for supporting the substrate W, and the annular region 111b is also referred to as a ring support surface for supporting the ring assembly 112.

[0052] In one embodiment, the main body portion 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 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 further has an annular region 111b. In addition, other components surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck and an annular insulating member, may have the annular region 111b. In this case, the ring assembly 112 can be disposed on the annular electrostatic chuck or the annular insulating member, or can be disposed on both the electrostatic chuck 1111 and the annular insulating member. Further, an RF or DC electrode may be disposed within the ceramic member 1111a, and in this case, the RF or DC electrode functions as a bias electrode. In addition, both the conductive member of the base 1110 and the RF or DC electrode can function as two bias electrodes.

[0053] 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 ring is formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

[0054] In addition, the substrate support portion 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 in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. In addition, the substrate support portion 11 may also include a heat transfer gas supply portion configured to supply a heat transfer gas between the back surface of the substrate W and the central region 111a.

[0055] The gas introduction portion is configured to introduce at least one process gas from the gas supply portion 20 into the plasma processing space 10s. In one embodiment, the gas introduction portion includes a central gas injector (CGI) 13. The central gas injector 13 is disposed above the substrate support portion 11 and is mounted at 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 introduction port 13c. The process gas supplied to the gas supply port 13a is introduced into the plasma processing space 10s from the gas introduction port 13c through the gas flow path 13b. In addition, the gas introduction portion may include one or more side gas injectors (SGIs) mounted at one or more openings formed in the side wall 102 in addition to or instead of the central gas injector 13.

[0056] The gas supply portion 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply portion 20 is configured to supply at least one process gas from the respective corresponding gas sources 21 to the gas introduction portion via the respective corresponding flow controllers 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Moreover, the gas supply portion 20 may include at least one flow modulation device for modulating the flow rate or pulsing at least one process gas.

[0057] 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), such as a source RF signal and a bias RF signal, to at least one bias electrode and the antenna 14. Thereby, plasma is formed from at least one process 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. In addition, by supplying the bias RF signal to at least one bias electrode, a bias potential can be generated on the substrate W, and ions in the formed plasma can be attracted to the substrate W.

[0058] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is configured to be coupled to the antenna 14 via at least one impedance matching circuit and 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 generation unit 31a may also be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to the antenna 14.

[0059] The second RF generation unit 31b is configured to be coupled to at least one bias electrode via at least one impedance matching circuit and 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 generation unit 31b may also 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 addition, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0060] In addition, the power supply 30 may include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a bias DC generation unit 32a. In one embodiment, the bias DC generation unit 32a is connected to at least one bias electrode and generates a bias DC signal. The generated bias DC signal is applied to at least one bias electrode.

[0061] In various embodiments, the bias DC signal may be pulsed. In this case, a DC-based voltage pulse sequence is applied to at least one bias electrode. The voltage pulses may have a pulse waveform such as rectangular, trapezoidal, triangular, or a combination thereof. In one embodiment, a waveform generation unit for generating a voltage pulse sequence from a DC signal is connected between the bias DC generation unit 32a and at least one bias electrode. Thus, the bias DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. The voltage pulses may have a positive polarity or a negative polarity. Additionally, the voltage pulse sequence may include one or more positive-polarity voltage pulses and one or more negative-polarity voltage pulses within one cycle. Further, the bias DC generation unit 32a may be provided together with the RF power supply 31, or may be provided in place of the second RF generation unit 31b.

[0062] 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 RF power supply 31 may be connected to both the outer coil and the inner coil, or may be connected to either the outer coil or the inner coil. In the former case, it may be the same RF generation unit that is connected to both the outer coil and the inner coil, or different RF generation units may be respectively connected to the outer coil and the inner coil.

[0063] The exhaust system 40 can be connected, for example, to a gas discharge 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 turbo molecular pump, a dry pump, or a combination thereof.

[0064] <An example of an etching method>

[0065] Figure 3 is a flowchart showing an example of an etching method (hereinafter also referred to as "this processing method") of an exemplary embodiment. As Figure 3 shown, in one embodiment, this processing method includes a step ST1 of providing a substrate and a step ST2 of performing etching. The processing in each step can be executed by Figure 2 the plasma processing system shown. Hereinafter, the case where the control unit 2 controls each part of the plasma processing apparatus 1 to execute this processing method on the substrate W will be described as an example.

[0066] (Step ST1: Providing a substrate)

[0067] In step ST1, the substrate W is provided into the plasma processing space 10s of the plasma processing apparatus 1. In one embodiment, the substrate W is provided to the central region 111a of the substrate support portion 11. And the substrate W is held on the substrate support portion 11 by the electrostatic chuck 1111.

[0068] Figure 4 This is a diagram showing an example of the cross-sectional structure of the substrate W. On the base film UF, a silicon film SiF and a mask MF are sequentially stacked on the substrate W. The substrate W can be used for the manufacture of semiconductor devices. Semiconductor devices include, for example, semiconductor memory devices such as DRAM and 3D-NAND flash memories, and logic devices.

[0069] In one example, the base film UF is a silicon wafer, an organic film formed on the silicon wafer, a dielectric film, a metal-containing film, a semiconductor film, etc. The base film UF can be formed by stacking multiple films.

[0070] The silicon film SiF is the film to be etched in this processing method. The silicon film SiF can be any one of a polycrystalline silicon film, a single-crystalline silicon film, and an amorphous silicon film. The silicon film SiF can contain impurities such as phosphorus, boron, and nitrogen.

[0071] The mask MF is a film that functions as a mask in the etching of the silicon film SiF. The mask MF can be a film different from the film to be etched. The mask MF can be at least one selected from a silicon-containing insulating film, a metal-containing film, and an organic film. The silicon-containing insulating film can be a silicon oxide film, a silicon nitride film, or a silicon oxynitride (SiON) film. The metal-containing film can be a film containing tungsten (W), titanium (Ti), or ruthenium (Ru). The mask MF can contain at least one selected from tungsten (W), tungsten silicide (WSi), tungsten silicon nitride (WSiN), tungsten carbide (WC), tungsten silicon carbide (WSiC), titanium nitride (TiN), titanium oxide (TiO), ruthenium (Ru), ruthenium carbide (RuC), ruthenium nitride (RuN), and ruthenium silicide (RuSi). The organic film can be an amorphous carbon film or a spin-on carbon film. In one embodiment, the mask MF contains at least one selected from silicon oxide, SiON, W, WSi, WSiN, WC, TiN, and TiO.

[0072] As Figure 4 shown, the mask MF defines at least one opening OP on the silicon film SiF. The opening OP is a space on the silicon film SiF and is surrounded by the sidewalls of the mask MF. That is, the upper surface of the silicon film SiF has a region covered by the mask MF and a region exposed at the bottom of the opening OP.

[0073] When looking down at the substrate W, that is, from Figure 4When observing the substrate W in the top-down direction, the opening OP can have any shape. For example, the shape can be a circle, an ellipse, a rectangle, a line, or a shape formed by combining one or more of them. The mask MF can also have multiple sidewalls, and multiple openings OP are defined by the multiple sidewalls. The multiple openings OP can each have a line shape and are arranged at a certain interval to form a line width and pitch (Line & Space) pattern. Additionally, the multiple openings OP can each have a hole shape to form an array pattern.

[0074] Each film (substrate film UF, silicon film SiF, mask MF) constituting the substrate W can be formed by CVD method, ALD method, spin coating method, etc. respectively. The opening OP can be formed by etching the mask MF. Additionally, the mask MF can also be formed by photolithography. Furthermore, each of the above films can be a flat film or a film with unevenness. Additionally, it can also be that the substrate W has other films under the substrate film UF, and the stacked film composed of the silicon film SiF and the substrate film UF functions as a multi-layer mask. That is, the stacked film of the silicon film SiF and the substrate film UF can be used as a multi-layer mask to etch the other film.

[0075] At least a part of the process of forming each film of the substrate W can be carried out Figure 2 in the space of the plasma processing chamber 10 shown. In one example, the step of etching the mask MF to form the opening OP can be executed in the plasma processing chamber 10. That is, the etching of the opening OP and the silicon film SiF described later can be continuously executed in the same chamber. Additionally, it can also be that after forming all or a part of each film of the substrate W in a device outside the plasma processing device 1 or in the chamber, the substrate W is fed into the plasma processing space 10s of the plasma processing device 1 and arranged in the central region 111a of the substrate support portion 11, thereby providing the substrate.

[0076] In one embodiment, after the substrate W is provided to the central region 111a of the substrate support 11, the temperature of the substrate support 11 is adjusted to a set temperature by the temperature control module. The temperature of the substrate support 11 is set, for example, in the range of 10°C or higher and 120°C or lower. In one example, adjusting or maintaining the temperature of the substrate support 11 includes adjusting or maintaining the temperature of the heat transfer fluid flowing in the flow path 1110a to a set temperature or a temperature different from the set temperature. In one example, adjusting or maintaining the temperature of the substrate support 11 includes controlling the pressure of the heat transfer gas (such as He) between the electrostatic chuck 1111 and the back surface of the substrate W. In addition, the moment when the heat transfer fluid starts to flow into the flow path 1110a can be before, after, or at the same time as the substrate W is placed on the substrate support 11. Further, in this processing method, the temperature of the substrate support 11 can be adjusted to the set temperature before step ST1. That is, the substrate W can be provided to the substrate support 11 after the temperature of the substrate support 11 is adjusted to the set temperature. In the steps after step ST1, the temperature of the substrate support 11 can be maintained at the set temperature adjusted in step ST1. In addition, the temperature of the substrate W on the substrate support 11 can be adjusted, for example, in the range of 10°C or higher and 250°C or lower. Adjusting or maintaining the temperature of the substrate W can be performed by adjusting the temperature of the substrate support 11 described above.

[0077] (Step ST2: Etching)

[0078] In step ST2, first, a processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The processing gas may contain a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas. The flow rate of the bromine-containing gas can be the highest relative to the total flow rate of the processing gas. The flow rates of the bromine-containing gas, the phosphorus fluoride gas, and the oxygen-containing gas can be 30% by volume or more, 50% by volume or more, 60% by volume or more, 70% by volume or more relative to the total flow rate of the processing gas. In addition, the processing gas may not contain a fluorine-containing gas other than phosphorus fluoride. The processing gas may not contain hydrogen fluoride gas, may not contain a fluorocarbon gas, may not contain a hydrofluorocarbon gas.

[0079] The flow rate of the bromine-containing gas can be greater than that of the phosphorus fluoride gas. The flow rate of the bromine-containing gas can be 10% by volume or more and 99% by volume or less of the flow rate of the processing gas (in the case where the processing gas contains other gases such as an inert gas, it is the flow rate after removing the other gas). The flow rate of the bromine-containing gas can be 30% by volume or more or 50% by volume or more of the flow rate of the processing gas. The flow rate of the bromine-containing gas can be 95% by volume or less or 90% by volume or less of the flow rate of the processing gas. The flow rate of the phosphorus fluoride gas can be 0.1% by volume or more and 50% by volume or less of the flow rate of the processing gas. The flow rate of the phosphorus fluoride gas can be 1% by volume or more, 2% by volume or more, or 3% by volume or more of the flow rate of the processing gas. The flow rate of the phosphorus fluoride gas can be 30% by volume or less, 20% by volume or less, 10% by volume or less, or 5% by volume or less of the flow rate of the processing gas. The ratio of the flow rate of the bromine-containing gas to the flow rate of the phosphorus fluoride gas (flow rate of bromine-containing gas / flow rate of phosphorus fluoride gas) can be in the range of 1 to 999.

[0080] The bromine-containing gas can be at least any one of HBr gas, Br2 gas, CBr2F2 gas, and S2Br2 gas, or can be at least any one of HBr gas and Br2 gas.

[0081] The phosphorus fluoride gas is a gas containing fluorine and phosphorus. In one example, it can be at least one selected from PF3 gas, PF5 gas, POF3 gas, HPF2 gas, H2PF3 gas, and HPF gas. In one example, the phosphorus fluoride gas can be at least any one of PF3 gas and PF5 gas.

[0082] The oxygen-containing gas can be, for example, at least one gas selected from O2 gas, CO gas, CO2 gas, H2O gas, and H2O2 gas. In one example, the oxygen-containing gas can be an oxygen-containing gas other than H2O gas and H2O2 gas, for example, at least one selected from O2 gas, CO gas, and CO2 gas.

[0083] The processing gas can further contain an inert gas. In one example, the inert gas can be a noble gas such as Ar gas, He gas, Kr gas, or nitrogen gas.

[0084] The processing gas can contain a gas containing a halogen different from bromine instead of or in addition to the bromine-containing gas. In one example, the processing gas can contain Cl2 gas.

[0085] The processing gas can contain a gas containing a halogen different from fluorine and phosphorus instead of or in addition to the phosphorus fluoride gas. In one example, the processing gas can contain PCl3 gas.

[0086] In step ST2, next, a plasma is generated from the processing gas, and the silicon film SiF is etched using this plasma. First, a generation source RF signal is supplied to the antenna 14. Thereby, a high-frequency electric field is generated between the antenna 14 and the substrate support portion 11, and a plasma is generated from the processing gas within the plasma processing space 10s. At this time, a bias signal can be supplied to the lower electrode of the substrate support portion 11. In this case, a bias potential is generated between the plasma and the substrate W. Active species such as ions and radicals in the plasma are attracted to the substrate W, and the silicon film SiF is etched by these active species. The bias signal can be a bias RF signal supplied from the RF power supply 31 or a bias DC signal supplied from the DC power supply 32.

[0087] Figure 5 FIG. is an example of a cross-sectional structure of the substrate W in the process of step ST2. As Figure 5 shown, by the process of step ST2, the portion of the silicon film SiF exposed at the opening OP is etched in the depth direction ( Figure 5 the direction from top to bottom in ), and a recess RC is formed. A protective film PF is formed on the sidewall of the recess RC and the surface of the mask MF.

[0088] In this processing method, the processing gas contains at least a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas. The active species generated from the bromine-containing gas mainly function as an etchant for removing the silicon film SiF. The active species generated from the oxygen-containing gas have the function of adjusting the amount of by-products (protective film PF) deposited on the sidewall of the recess RC and the surface of the mask MF. The active species generated from the phosphorus fluoride gas have the function of reducing the by-products (protective film PF) deposited near the opening OP of the mask MF.

[0089] In one example, using bromide ions (Br + ) derived from the bromine-containing gas and oxygen radicals (O*) derived from the oxygen-containing gas, a protective film PF containing a silicon-based by-product (SiBrO) is formed on the sidewall of the recess RC and the surface of the mask MF. In one example, using phosphorus fluoride ions (PFx + ) derived from the phosphorus fluoride gas, the by-products (excess protective film PF) deposited near the opening OP of the mask MF are removed. Thereby, it is possible to suppress the blockage or narrowing of the opening OP of the mask MF. In addition, since the phosphorus fluoride gas is difficult to dissociate and the amount of F radicals (F*) is reduced, it is possible to suppress the erosion (bowing, sidewall bending) of the sidewall of the recess RC. In one example, using phosphorus fluoride ions (PFx + ) derived from the phosphorus fluoride gas, the protective film PF formed at the bottom of the recess RC is removed. Thereby, the silicon film SiF at the bottom of the recess RC is exposed, and bromide ions (Br +) Promote the etching of the silicon film SiF in the depth direction. In one example, by using a phosphorus component such as phosphorus fluoride radicals (PFx*) derived from phosphorus fluoride gas, a by-product is deposited on the sidewalls of the recess RC. Thereby, it is possible to suppress the erosion (bending) of the sidewalls of the recess RC, and the etching selectivity is improved.

[0090] According to this exemplary embodiment, the etching method includes: step (ST1) of providing a substrate W on a substrate support portion 11 in a chamber 10, where the substrate W has a silicon film SiF and a mask MF on the silicon film SiF, and the mask MF contains silicon oxide; and step (ST2) of supplying a processing gas containing a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas into the chamber 10 and generating a plasma from the processing gas to etch the silicon film SiF. Thereby, it is possible to suppress the narrowing near the opening OP of the mask MF and the erosion of the sidewalls of the recess RC of the silicon film SiF, and thus it is possible to suppress the occurrence of shape abnormalities during the etching of the silicon film SiF.

[0091] <Example>

[0092] Figure 6 It is a graph showing the amount of F radicals generated when generating a plasma using various gases. In the experiment, a processing gas containing SF6 gas, NF3 gas, CF4 gas, or PF3 gas was used to generate a plasma, and the amount of generated F radicals was measured by an emission spectroscopy apparatus. As Figure 6 shown, in the case of using PF3 gas, the amount of generated F radicals is small. In addition, the ionization energy of PF3 gas is lower than that of NF3 gas, and PF3 gas is easily ionized. From this, it can be known that compared with the plasma generated from a processing gas containing NF3 gas, in the plasma generated from a processing gas containing PF3 gas, the amount of F radicals is small, the amount of phosphorus fluoride ions is large, and the radical / ion ratio decreases. Since there are few F radicals, while the excess protective film PF near the opening OP can be removed, it is possible to suppress the erosion of the protective film PF on the sidewalls of the recess RC at a position deeper than the opening OP. Since there are many phosphorus fluoride ions, the protective film PF formed at the bottom of the recess RC can be etched by the phosphorus fluoride ions to expose the silicon film SiF, and the bromine ions can reach the silicon film SiF. Thereby, it is possible to promote the etching of the silicon film SiF in the depth direction.

[0093] Figure 7 It shows the etching results of the silicon film SiF in the case where PF3 gas is used as part of the processing gas and in the case where NF3 gas is used. Figure 7 It is a graph schematically showing an image obtained by photographing the etched silicon film SiF using a scanning electron microscope. The etching was performed by setting the set temperature of the substrate support portion to 60°C and setting the flow rates of various gases to the flow rate ratios shown in Table 1.

[0094] [Table 1]

[0095]

[0096] In the case of using PF3 gas, there are no deposits clogging the opening near the opening OP of the mask MF. For the case of using NF3 gas and the case of using PF3 gas, the dimensions of the line widths at the upper, middle, and lower parts of the silicon film SiF are measured respectively. As a result, it is confirmed that, compared with the case of using NF3 gas, in the case of using PF3 gas, there is no deviation (fluctuation) in the dimensions of the line width of the silicon film SiF, and the shape abnormality is suppressed. The etching rates (ER) are calculated respectively for the case of using NF3 gas and the case of using PF3 gas. As a result, it is confirmed that, compared with the case of using NF3 gas, in the case of using PF3 gas, the etching rate is increased. For the case of using NF3 gas and the case of using PF3 gas, the depth of the holes in the silicon film SiF and the thickness of the mask are measured respectively. As a result, it is confirmed that, compared with the case of using NF3 gas, in the case of using PF3 gas, the etching selectivity is increased.

[0097] In the above embodiments, in the etching step ST2, the ratio of the flow rate of the phosphorus fluoride gas to the flow rate of the processing gas can be changed. In one embodiment, the ratio (Ra) of the flow rate of the phosphorus fluoride gas to the flow rate of the processing gas can be changed according to the depth of the concave portion RC of the silicon film SiF. In one embodiment, the ratio (Ra) of the flow rate of the phosphorus fluoride gas can be increased as the concave portion RC of the silicon film SiF becomes deeper. It is also possible to decrease the ratio (Ra) of the flow rate of the phosphorus fluoride gas as the concave portion RC of the silicon film SiF becomes deeper. In one embodiment, the etching step ST2 may include a first etching step ST21 and a second etching step ST22. The first etching step ST21 is a step of etching the silicon film SiF using the first plasma generated from the first processing gas, wherein the first processing gas contains the phosphorus fluoride gas at a first flow rate ratio. The second etching step ST22 is a step of etching the silicon film SiF using the second plasma generated from the second processing gas, wherein the second processing gas does not contain the phosphorus fluoride gas or contains the phosphorus fluoride gas at a second flow rate ratio smaller than the first flow rate ratio. The second etching step ST22 can be executed after the first etching step ST1, or the first etching step ST21 can be executed after the second etching step ST22, or the first etching step ST21 and the second etching step ST22 can be repeatedly executed multiple times. The first processing gas can be the processing gas containing the bromine-containing gas, the phosphorus fluoride gas, and the oxygen-containing gas described in the above embodiments. The second processing gas can be the processing gas containing the bromine-containing gas, the phosphorus fluoride gas, and the oxygen-containing gas described in the above embodiments, or can be the processing gas containing the bromine-containing gas and the oxygen-containing gas but not containing the phosphorus fluoride.

[0098] In the above-described embodiment, the etching step ST2 may include a first period in which phosphorous fluoride gas is not supplied and a second period in which phosphorous fluoride gas is supplied. In one embodiment, it may be that, in the first period of the etching step ST2, plasma is generated from a process gas containing a bromine-containing gas and an oxygen-containing gas to etch the silicon film SiF, and then, in the second period, plasma is generated from a process gas containing a bromine-containing gas, an oxygen-containing gas, and phosphorous fluoride gas to etch the silicon film SiF. The first period and the second period may be alternately repeated.

[0099] In the above-described embodiment, the film to be etched is a silicon film, but it may also be a silicon-containing conductive film. The silicon-containing conductive film may be a film containing silicon and germanium, or a film containing silicon and a metal. That is, the silicon-containing conductive film may be a metal silicide such as SiGe or WSi.

[0100] In the above-described embodiment, the present processing method is not limited to being performed in an inductively coupled plasma processing apparatus, and may also be performed in other types of plasma processing apparatuses. For example, it may be performed in a plasma processing apparatus that generates capacitively coupled plasma, a plasma processing apparatus that generates ECR plasma, a plasma processing apparatus that generates helicon wave-excited plasma, or a plasma processing apparatus that generates surface wave plasma.

[0101] The present disclosure may include, for example, the following configurations.

[0102] (Note 1)

[0103] An etching method, comprising:

[0104] Step (a) of providing a substrate onto a substrate support portion disposed in a chamber, wherein the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; and

[0105] Step (b) of supplying a process gas containing a bromine-containing gas, phosphorous fluoride gas, and an oxygen-containing gas into the chamber and generating plasma from the process gas to etch the silicon film or the silicon-containing conductive film.

[0106] (Note 2)

[0107] The etching method according to Note 1, wherein the silicon-containing conductive film is a film containing silicon and containing germanium or a metal.

[0108] (Note 3)

[0109] The etching method according to Note 1 or 2, wherein the mask contains at least one selected from a silicon-containing insulating film, a metal-containing film, and an organic film.

[0110] (Note 4)

[0111] The etching method according to any one of Notes 1 to 3, wherein, in the step (b), the ratio of the flow rate of the phosphorus fluoride gas to the flow rate of the processing gas is changed.

[0112] (Note 5)

[0113] The etching method according to any one of Notes 1 to 4, wherein,

[0114] the step (b) includes:

[0115] Step (b1), etching the silicon film or the silicon-containing conductive film with a first plasma generated from a first processing gas, wherein the first processing gas contains a phosphorus fluoride gas at a first flow rate ratio; and

[0116] Step (b2), etching the silicon film or the silicon-containing conductive film with a second plasma generated from a second processing gas, wherein the second processing gas does not contain a phosphorus fluoride gas or contains a phosphorus fluoride gas at a second flow rate ratio smaller than the first flow rate ratio.

[0117] (Note 6)

[0118] The etching method according to Note 5, wherein the step (b2) is performed after the step (b1).

[0119] (Note 7)

[0120] The etching method according to Note 5, wherein the step (b1) is performed after the step (b2).

[0121] (Note 8)

[0122] The etching method according to any one of Notes 5 to 7, wherein the steps (b1) and (b2) are repeatedly performed multiple times.

[0123] (Note 9)

[0124] The etching method according to any one of Notes 1 to 8, wherein the flow rate of the bromine-containing gas is greater than the flow rate of the phosphorus fluoride gas.

[0125] (Note 10)

[0126] The etching method according to any one of Notes 1 to 9, wherein the flow rate of the bromine-containing gas is 10 vol% or more and 99.9 vol% or less of the flow rate of the processing gas.

[0127] (Note 11)

[0128] The etching method according to any one of Notes 1 to 10, wherein the flow rate of the phosphorus fluoride gas is 0.1% by volume or more and 50% by volume or less of the flow rate of the processing gas.

[0129] (Note 12)

[0130] The etching method according to any one of Notes 1 to 11, wherein the ratio of the flow rate of the bromine-containing gas to the flow rate of the phosphorus fluoride gas is in the range of 1 to 999.

[0131] (Note 13)

[0132] The etching method according to any one of Notes 1 to 12, wherein the bromine-containing gas is at least one of HBr gas and Br2 gas.

[0133] (Note 14)

[0134] The etching method according to any one of Notes 1 to 13, wherein the phosphorus fluoride gas is at least one of PF3 gas and PF5 gas.

[0135] (Note 15)

[0136] The etching method according to any one of Notes 1 to 14, wherein the oxygen-containing gas is at least one selected from O2 gas, CO gas, and CO2 gas.

[0137] (Note 16)

[0138] An etching method, comprising:

[0139] Step (a) of providing a substrate onto a substrate support portion disposed in a chamber, wherein the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; and

[0140] Step (b) of supplying a processing gas containing a first gas, a second gas, and an oxygen-containing gas into the chamber and generating a plasma from the processing gas to etch the silicon film or the silicon-containing conductive film, wherein the first gas contains a first halogen and the second gas contains a second halogen and phosphorus.

[0141] (Note 17)

[0142] The etching method according to Note 16, wherein the silicon-containing conductive film is a film containing silicon and containing germanium or a metal.

[0143] (Note 18)

[0144] The etching method according to Note 16 or 17, wherein in step (b), the ratio of the flow rate of the second gas to the flow rate of the processing gas is changed.

[0145] (Note 19)

[0146] The etching method according to any one of Notes 16 to 18, wherein the mask comprises at least one selected from a silicon-containing insulating film, a metal-containing film, and an organic film.

[0147] (Note 20)

[0148] The etching method according to any one of Notes 16 to 19, wherein the mask comprises at least one selected from silicon oxide, SiON, W, WSi, WSiN, WC, TiN, and TiO.

[0149] (Note 21)

[0150] The etching method according to any one of Notes 16 to 20, wherein the first gas is at least one selected from HBr gas, Br2 gas, and Cl2 gas.

[0151] (Note 22)

[0152] The etching method according to any one of Notes 16 to 21, wherein the second gas is at least one selected from PF3 gas, PF5 gas, and PCl3 gas.

[0153] (Note 23)

[0154] A plasma processing apparatus includes a chamber, a substrate support portion disposed in the chamber, a plasma generation portion, and a control portion, wherein the control portion performs:

[0155] Controlling (a) to provide a substrate onto the substrate support portion, wherein the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; and

[0156] Controlling (b) to supply a processing gas containing a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas into the chamber, and generating plasma from the processing gas to etch the silicon film or the silicon-containing conductive film.

[0157] In the above exemplary embodiments, the plasma processing apparatus and the plasma processing method can be variously modified without departing from the scope and gist of the present disclosure. For example, within the ordinary creative ability of those skilled in the art, a part of the constituent elements in one embodiment can be added to other embodiments. In addition, a part of the constituent elements in one embodiment can be replaced with the corresponding constituent elements in other embodiments.

[0158] Explanation of reference numerals

[0159] 1... Plasma processing apparatus, 2... Control unit, 10... Plasma processing chamber, 11... Substrate support unit, 12... Plasma generation unit.

Claims

1. An etching method, wherein, Comprising: Step (a), providing a substrate onto a substrate support portion disposed in a chamber, wherein the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; And Step (b), supplying a processing gas containing a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas into the chamber, and generating a plasma from the processing gas to etch the silicon film or the silicon-containing conductive film.

2. The etching method according to claim 1, wherein The silicon-containing conductive film is a film containing silicon and containing germanium or a metal.

3. The etching method according to claim 1, wherein The mask contains at least one selected from a silicon-containing insulating film, a metal-containing film, and an organic film.

4. The etching method according to claim 1, wherein In step (b), the ratio of the flow rate of the phosphorus fluoride gas to the flow rate of the processing gas is changed.

5. The etching method according to claim 1, wherein Step (b) includes: Step (b1), etching the silicon film or the silicon-containing conductive film with a first plasma generated from a first processing gas, wherein the first processing gas contains the phosphorus fluoride gas at a first flow rate ratio; and Step (b2), etching the silicon film or the silicon-containing conductive film with a second plasma generated from a second processing gas, wherein the second processing gas does not contain the phosphorus fluoride gas or contains the phosphorus fluoride gas at a second flow rate ratio less than the first flow rate ratio.

6. The etching method according to claim 5, wherein Step (b2) is performed after step (b1).

7. The etching method according to claim 5, wherein Step (b1) is performed after step (b2).

8. The etching method according to claim 5, wherein Steps (b1) and (b2) are repeatedly performed multiple times.

9. The etching method according to claim 1, wherein The flow rate of the bromine-containing gas is greater than the flow rate of the phosphorus fluoride gas.

10. The etching method according to claim 1, wherein The flow rate of the bromine-containing gas is 10% by volume or more and 99% by volume or less of the flow rate of the processing gas.

11. The etching method according to claim 1, wherein The flow rate of the phosphorus fluoride gas is 0.1% by volume or more and 50% by volume or less of the flow rate of the processing gas.

12. The etching method according to claim 1, wherein The ratio of the flow rate of the bromine-containing gas to the flow rate of the phosphorus fluoride gas is in the range of 1 to 999.

13. The etching method according to claim 1, wherein The bromine-containing gas is at least one of HBr gas and Br2 gas.

14. The etching method according to claim 1, wherein The phosphorus fluoride gas is at least one of PF3 gas and PF5 gas.

15. The etching method according to claim 1, wherein The oxygen-containing gas is at least one selected from O2 gas, CO gas, and CO2 gas.

16. An etching method, wherein, Comprising: Step (a): Provide a substrate onto a substrate support disposed within a chamber, wherein the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; and Step (b): Supply a processing gas containing a first gas, a second gas, and an oxygen-containing gas into the chamber, and generate a plasma from the processing gas to etch the silicon film or the silicon-containing conductive film, wherein the first gas contains a first halogen, and the second gas contains a second halogen and phosphorus.

17. The etching method according to claim 16, wherein the silicon-containing conductive film is a film containing silicon and containing germanium or a metal.

18. The etching method according to claim 16, wherein in step (b), change the ratio of the flow rate of the second gas to the flow rate of the processing gas.

19. The etching method according to claim 16, wherein the mask contains at least one selected from a silicon-containing insulating film, a metal-containing film, and an organic film.

20. The etching method according to claim 16, wherein the mask contains at least one selected from silicon oxide, SiON, W, WSi, WSiN, WC, TiN, and TiO.

21. The etching method according to claim 16, wherein the first gas is at least one selected from HBr gas, Br2 gas, and Cl2 gas.

22. The etching method according to claim 16, wherein the second gas is at least one selected from PF3 gas, PF5 gas, and PCl3 gas.

23. A plasma processing apparatus, comprising a chamber, a substrate support disposed within the chamber, a plasma generation unit, and a control unit, wherein the control unit performs: Control (a): Provide a substrate onto the substrate support, wherein the substrate has a silicon film or a silicon-containing conductive film and a mask on the silicon film or the silicon-containing conductive film; and Control (b): Supply a processing gas containing a bromine-containing gas, a phosphorus fluoride gas, and an oxygen-containing gas into the chamber, and generate a plasma from the processing gas to etch the silicon film or the silicon-containing conductive film.

Images