Plasma treatment method and plasma treatment apparatus

Abstract

To provide a plasma processing method and a plasma processing apparatus, achieving a high etching rate while improving an etching shape.SOLUTION: A plasma processing method includes: a step S1 for providing, on a substrate support within a chamber, a substrate that has a carbon-containing film and a silicon-containing mask which is formed on the carbon-containing film; a step S2 for supplying a coolant to the substrate support to control the temperature of the substrate support; a step S3 for supplying a process gas into the chamber; and a step S4 for generating plasma from the process gas within the chamber with a source RF signal and supplying a bias signal to the substrate support to etch the carbon-containing film. The coolant in the step S2 is set so that the temperature of the substrate or of the surface of the substrate support during plasma etching is -70°C or above and 100°C or below. The source RF signal in the step S4 is an RF signal which has power of 2 kW or greater, and the bias signal is a RF signal which has power of 2 kW or greater or a DC signal which includes a voltage pulse of 2 kV or greater.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] As a technique for improving the shape of grooves formed by etching, there is a technique described in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique for realizing a high etching rate while improving the processed shape of etching.

Means for Solving the Problems

[0005] In one exemplary embodiment of the present disclosure, a plasma processing method performed in an inductively coupled plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a carbon-containing film and a silicon-containing mask formed on the carbon-containing film onto a substrate support in the chamber; (b) supplying a refrigerant to the substrate support to control the temperature of the substrate support; (c) supplying a processing gas into the chamber; and (d) while step (b) is being performed, generating plasma from the processing gas in the chamber by a source RF signal and supplying a bias signal to the substrate support to etch the carbon-containing film, wherein in step (d), the refrigerant in step (b) is set to a target temperature of -70°C or more and 100°C or less for the substrate or substrate support during plasma etching; the source RF signal in step (d) is an RF signal with a power of 2 kW or more; and the bias signal in step (d) is a bias RF signal with a power of 2 kW or more, or a bias DC signal including a voltage pulse of 2 kV or more. A plasma treatment method is provided. [Effects of the Invention]

[0006] According to one exemplary embodiment of the present disclosure, a technology can be provided that improves the etched shape while achieving a high etching rate. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram schematically shows an example of the configuration of a plasma processing apparatus. [Figure 2] This flowchart shows an example of the main steps in this plasma treatment method. [Figure 3A] This is a schematic diagram showing an example of a cross-section of a substrate film structure. [Figure 3B] This is a schematic diagram showing an example of a cross-section of the film structure of an etched substrate. [Figure 4] This figure illustrates an example of an etching target film etched under conditions A and B. [Figure 5]This diagram schematically shows an example of the configuration of a plasma processing apparatus. [Figure 6] This is a flowchart showing an example of the plasma generation process. [Figure 7] This diagram illustrates an example of the relationship between substrate temperature and etching shape. [Modes for carrying out the invention]

[0008] The embodiments of this disclosure are described below.

[0009] In one exemplary embodiment, a plasma processing method is provided that is performed in an inductively coupled plasma processing apparatus having a chamber, comprising the steps of: (a) providing a substrate having a carbon-containing film and a silicon-containing mask formed on the carbon-containing film onto a substrate support in the chamber; (b) supplying a refrigerant to the substrate support to control the temperature of the substrate support; (c) supplying a processing gas into the chamber; and (d) while step (b) is being performed, generating plasma from the processing gas in the chamber by a source RF signal and supplying a bias signal to the substrate support to etch the carbon-containing film, wherein in step (d), the refrigerant in step (b) is set so that the temperature of the substrate or substrate support during plasma etching is between -70°C and 100°C, the source RF signal in step (d) is an RF signal with a power of 2kW or more, and the bias signal in step (d) is a bias RF signal with a power of 2kW or more, or a bias DC signal including a voltage pulse of 2kV or more.

[0010] In one exemplary embodiment, the method further comprises (e) measuring the temperature of at least one of the substrate or substrate support using a temperature sensor, and (f) adjusting the temperature of at least one of the source RF signal in (d), the bias signal in (d), and the set temperature of the refrigerant in (b) based on the temperature measured in (e).

[0011] In one exemplary embodiment, (d) includes the steps of (d1) adjusting the temperature of at least one of the substrate or substrate support to a first temperature, and (d2) adjusting the temperature of at least one of the substrate or substrate support to a second temperature higher than the first temperature. In this exemplary embodiment, (d1) and (d2) may be performed in either order.

[0012] In one exemplary embodiment, (d1) and (d2) are performed in this order.

[0013] In one exemplary embodiment, (d) further comprises the step of alternately repeating (d1) and (d2).

[0014] In one exemplary embodiment, (d1) and (d2) have at least one of the following steps: (g), (h), (i), (j), (k). (g) In step (d1), a bias signal of the first output is supplied to the substrate support unit, and in step (d2), a bias signal of the second output, which is greater than the first output, is supplied to the substrate support unit. (h)(d1) A bias signal with a first duty cycle is supplied to the substrate support, and (d2) A bias signal with a second duty cycle greater than the first duty cycle is supplied to the substrate support. (i) In step (d1), a bias signal of a first frequency is supplied to the substrate support; and in step (d2), a bias signal of a second frequency lower than the first frequency is supplied to the substrate support. (j)(d1) A step of supplying a heat transfer gas at a first pressure between the substrate and the substrate support, and (d2) A step of supplying a heat transfer gas at a second pressure lower than the first pressure between the substrate and the substrate support, (k) A step of setting the temperature of the refrigerant to a first temperature in (d1) and setting the temperature of the refrigerant to a second temperature higher than the first temperature in (d2).

[0015] In one exemplary embodiment, the processing gas includes an oxygen-containing gas and a sulfur-containing gas.

[0016] In one exemplary embodiment, the source RF signal has a frequency of 13 MHz or higher.

[0017] In one exemplary embodiment, the bias RF signal has a frequency of 13 MHz or lower.

[0018] In one exemplary embodiment, the carbon-containing film includes an amorphous carbon film.

[0019] In one exemplary embodiment, the silicon-containing mask includes a silicon oxynitride film.

[0020] In one exemplary embodiment, an inductively coupled plasma processing apparatus having a chamber, comprising: a substrate support portion provided in the chamber for supporting a substrate having a carbon-containing film and a silicon-containing mask formed on the carbon-containing film; a temperature adjustment portion for adjusting the temperature of the substrate support portion by supplying a refrigerant to the substrate support portion; a process gas supply portion for supplying a process gas into the chamber; a source RF signal generation portion for generating a source RF signal; a bias signal supply portion for supplying a bias signal to the substrate support portion; and a control portion. The control portion: (a) in a state where the substrate is provided on the substrate support portion in the chamber; (b) controls the temperature of the substrate support portion by supplying a refrigerant to the substrate support portion by the temperature adjustment portion; (c) supplies a process gas into the chamber by the process gas supply portion; (d) in a state where (b) is being performed, generates plasma from the process gas in the chamber by the source RF signal generated by the source RF signal generation portion, and supplies a bias signal to the substrate support portion by the bias signal supply portion to etch the carbon-containing film. In (d), the refrigerant in (b) is set so that the substrate or the substrate support portion during plasma etching reaches a target temperature of -70 °C or higher and 100 °C or lower. The source RF signal in the step of (d) is an RF signal having a power of 2 kW or higher. The bias signal in the step of (d) is a bias RF signal having a power of 2 kW or higher or a bias DC signal including a voltage pulse of 2 kV or higher. There is provided a plasma processing apparatus that executes the control.

[0021] Hereinafter, each embodiment of this disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are denoted by the same reference numeral, and redundant explanations are omitted. Unless otherwise specified, positional relationships such as top, bottom, left, and right will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and actual ratios are not limited to those shown.

[0022] <Configuration of Plasma Processing Device 1> The following describes an example configuration of a plasma processing system. Figure 1 is a diagram illustrating an example configuration of an inductively coupled plasma processing apparatus 1. A plasma processing method according to one exemplary embodiment (hereinafter referred to as "this plasma processing method") is performed using the plasma processing apparatus 1.

[0023] The plasma processing system includes an inductively coupled plasma processing apparatus 1 and a control unit 2. The inductively coupled plasma processing apparatus 1 includes a plasma processing chamber (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 50. The plasma processing apparatus 1 also includes a substrate support unit 11, a gas introduction unit 13, and an antenna 14. The substrate support unit 11 is located inside the plasma processing chamber 10. The antenna 14 is an example of an inductively coupled plasma (ICP) source. The antenna 14 is located on or above the plasma processing chamber 10 (i.e., on or above the dielectric window 50). The plasma processing chamber 10 has a plasma processing space 10s defined by the dielectric window 50, the side walls 51 of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s, and at least one gas outlet for discharging gas from the plasma processing space. The plasma processing chamber 10 is grounded.

[0024] The substrate support portion 11 includes a main body portion 60 and a ring assembly 61. The main body portion 60 has a central region 60a for supporting the substrate W and an annular region 60b for supporting the ring assembly 61. A wafer is an example of a substrate W. In a plan view, the annular region 60b of the main body portion 60 surrounds the central region 60a of the main body portion 60. The substrate W is placed on the central region 60a of the main body portion 60, and the ring assembly 61 is placed on the annular region 60b of the main body portion 60 so as to surround the substrate W on the central region 60a of the main body portion 60. Therefore, the central region 60a is also called the substrate support surface for supporting the substrate W, and the annular region 60b is also called the ring support surface for supporting the ring assembly 61.

[0025] In one embodiment, the main body 60 includes a base 70 and an electrostatic chuck 71. The base 70 includes a conductive member. The conductive member of the base 70 can function as a bias electrode. The electrostatic chuck 71 is placed on the base 70. The electrostatic chuck 71 includes a ceramic member 71a and an electrostatic electrode 71b placed within the ceramic member 71a. The ceramic member 71a has a central region 60a. In one embodiment, the ceramic member 71a also has an annular region 60b. Other members surrounding the electrostatic chuck 71, such as an annular electrostatic chuck or an annular insulating member, may also have an annular region 60b. In this case, the ring assembly 61 may be placed on the annular electrostatic chuck or the annular insulating member, or on both the electrostatic chuck 71 and the annular insulating member. Furthermore, an RF or DC electrode may be placed within the ceramic member 71a, in which case the RF or DC electrode functions as a bias electrode. The conductive member of the base 70 and the RF or DC electrode may both function as two bias electrodes.

[0026] The ring assembly 61 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.

[0027] The substrate support portion 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 71, the ring assembly 61, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 70a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 70a. In one embodiment, the flow path 70a is formed within the base 70, and one or more heaters are arranged within the ceramic member 71a of the electrostatic chuck 71.

[0028] The temperature control unit 80 is an example of a temperature control module. In one embodiment, the temperature control unit 80 has a flow path 70a and a refrigerant circulator 90 connected to the flow path 70a. The refrigerant circulator 90 can set the refrigerant to a predetermined temperature and supply and circulate the refrigerant in the flow path 70a. In one embodiment, the refrigerant circulator 90 can set the temperature of the refrigerant to a temperature of -50°C or lower. Setting the temperature of the refrigerant includes not only setting the temperature of the refrigerant to the set temperature, but also setting the refrigerant circulator 90 so that the refrigerant reaches the set temperature. The temperature control unit 80 can supply the refrigerant, whose temperature has been set in the refrigerant circulator 90, to the substrate support unit 11 through the flow path 70a and adjust the temperature of the substrate support unit 11.

[0029] Furthermore, the substrate support portion 11 may include a heat transfer gas supply portion 100 configured to supply heat transfer gas between the back surface of the substrate W and the central region 60a. In one embodiment, the heat transfer gas supply portion 100 has a gas supply line 101 provided on the substrate support portion 11. The gas supply line 101 supplies heat transfer gas (e.g., He gas) from the heat transfer gas supply mechanism 102 to the gap between the upper surface of the electrostatic chuck 71 and the back surface of the substrate W. The heat transfer gas supply portion 100 can supply heat transfer gas at a predetermined pressure.

[0030] The substrate support section 11 is provided with lifters (lift pins), which are not shown. In one embodiment, the lifters are arranged in a plurality of through holes that penetrate the substrate support section 11 in the vertical direction, and move vertically within the through holes by a drive device, which is not shown. In one embodiment, the substrate W is transported into and out of the chamber 10 by a transport arm, which is not shown. The lifters support the substrate W on the substrate support section 11, raise and lower it, and exchange the substrate W with the transport arm, thereby allowing the substrate W to be placed on the substrate support section 11.

[0031] The gas introduction unit 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The gas introduction unit 13 is an example of a processing gas supply unit. In one embodiment, the gas introduction unit 13 includes a Center Gas Injector (CGI) 110. The Center Gas Injector 110 is located above the substrate support unit 11 and is attached to a central opening formed in the dielectric window 50. The Center Gas Injector 110 has at least one gas supply port 110a, at least one gas flow path 110b, and at least one gas introduction port 110c. The processing gas supplied to the gas supply port 110a passes through the gas flow path 110b and is introduced into the plasma processing space 10s from the gas introduction port 110c. In one embodiment, the processing gas includes an oxygen-containing gas (for example, a gas containing O2) and a sulfur-containing gas (for example, a gas containing COS). In addition, the gas introduction section 13 may include, in addition to or instead of, the central gas injection section 110, one or more side gas injection sections (SGIs) attached to one or more openings formed in the side wall 51.

[0032] 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 introduction unit 13 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 one or more flow modulation devices that modulate or pulse the flow rate of at least one processing gas. The gas supply unit 20 may be included as part of the gas introduction unit 13.

[0033] The power supply 30 includes an RF (radio frequency) 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 antenna 14. This causes plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power supply 31 can function as at least part of a plasma generation unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to at least one bias electrode, a bias potential is generated on the substrate W, which can attract ions in the formed plasma to the substrate W.

[0034] 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 an example of a source RF signal generation unit that generates a source RF signal. The first RF generation unit 31a is coupled to the antenna 14 and configured to generate a source RF signal (source RF power) for plasma generation via at least one impedance matching circuit. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the source RF signal has a frequency of 13 MHz or higher. The source RF power has a power of 2 kW or higher. 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.

[0035] The second RF generation unit 31b is an example of a bias signal supply unit that supplies a bias RF signal, which is a bias RF signal, to the substrate support unit 11. The second RF generation unit 31b is configured to be coupled to at least one bias electrode of the substrate support unit 11 via at least one impedance matching circuit and to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the bias RF signal has a frequency of 13 MHz or less. The bias RF signal includes a bias RF signal having a power of 2 kW or more. 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.

[0036] Furthermore, 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. The bias DC generation unit 32a is an example of a bias signal supply unit that supplies a bias signal, which is a bias DC signal including a voltage pulse, to the substrate support unit 11. In one embodiment, the bias DC generation unit 32a is connected to at least one bias electrode of the substrate support unit 11 and is configured to generate a bias DC signal (bias DC power). The generated bias DC signal is applied to at least one bias electrode.

[0037] In various embodiments, the bias DC signal may be pulsed. In one embodiment, the bias DC generation unit 32a can supply the substrate support unit 11 with a bias DC signal including a voltage pulse of 3kV (RMS) or more. In this case, a sequence of DC-based voltage pulses is applied to at least one bias electrode. The voltage pulse may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses 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 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 bias DC generation unit 32a may be provided in addition to the RF power supply 31, or it may be provided in place of the second RF generation unit 31b.

[0038] 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 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.

[0039] 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.

[0040] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described herein. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, the control unit 2 controls the operation of the gas introduction unit, the power supply 30 (including the first RF generation unit 31a, the second RF generation unit 31b, and the bias DC generation unit 32a), the temperature control unit 80, the exhaust system 40, the heat transfer gas supply unit 100, and so on. 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 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or it may be retrieved via a medium when needed. The acquired program is stored in the memory unit 2a2 and read from the memory 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 memory 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).

[0041] <An example of this plasma treatment method> Figure 2 is a flowchart showing the main steps of the plasma processing method performed by the plasma processing apparatus 1. In one embodiment, the plasma processing method uses an inductively coupled plasma processing apparatus 1 to etch a substrate W having a carbon-containing film (organic film) and a silicon-containing mask formed on the carbon-containing film. In one embodiment, the plasma processing method includes deep hole machining with a high aspect ratio (ratio of depth to width of processed recess (depth / width)) of 30 or more.

[0042] First, in one embodiment, a substrate W having a base film 130 as shown in Figure 3A, a carbon-containing film 131, and a silicon-containing mask 132 is prepared. An example of the carbon-containing film 131 is an amorphous carbon film. An example of the silicon-containing mask 132 is an silicon dioxide mask. The substrate W is transported into the chamber 10 by a transport arm, placed on the substrate support section 11 by a lifter, and held on the substrate support section 11 by suction. As a result, as shown in Figure 1, the substrate W is provided on the substrate support section 11 (step S1 in Figure 2). The carbon-containing film 131 and the silicon-containing mask 132 may be formed on the substrate W within the chamber 10.

[0043] Next, in the refrigerant circulator 90, the refrigerant is set so that the substrate W or substrate support portion 11 during plasma etching reaches a target temperature of -70°C to 100°C. As an example, the refrigerant is set to a predetermined temperature (cryogenic temperature) of -50°C or lower so that the surface of the substrate support portion 11 reaches the above target temperature. The refrigerant is supplied from the refrigerant circulator 90 to the flow path 70a, and the temperature of the substrate support portion 11 is controlled by the refrigerant (step S2 in Figure 2). Note that the timing at which the refrigerant is supplied to the substrate support portion 11 is not limited to after the substrate W has been provided to the substrate support portion 11, but may also be before the substrate W has been provided to the substrate support portion 11, or may be simultaneous with the provision of the substrate W to the substrate support portion 11.

[0044] With the substrate support section 11 temperature-controlled by a refrigerant, a processing gas is supplied to the processing space 10s of the chamber 10 by the gas introduction section 13 (step S3 in Figure 2). In one embodiment, the processing gas includes an oxygen-containing gas (for example, a gas containing O2) and a sulfur-containing gas (for example, a gas containing COS) for etching the carbon-containing film 131.

[0045] Next, in one embodiment, a source RF signal is supplied to the antenna 14 by the first RF generation unit 31a, and plasma is generated from the processing gas in the chamber 10 by the source RF signal. A bias signal is supplied to the substrate support unit 11 by the second RF generation unit 31b (step S4 (plasma generation step S4) in Figure 2). This plasma generation step S4 is performed with the substrate support unit 11 temperature controlled by a cryogenic coolant. As a result, in one embodiment, the carbon-containing film 131 of the substrate W is etched as shown in Figure 3B, and a recess 133 is formed. The recess 133 is an example of the processed shape of the carbon-containing film. At this time, the source RF signal is a high-source RF signal with a power of 2kW or more, and the bias signal is a high-bias RF signal with a power of 2kW or more. The source RF signal may have a power of 4kW or more. The source RF signal may have a power of 30kW or less. The bias signal may have a power of 4kW or more. The bias signal may have a power of 30kW or less.

[0046] In one embodiment, the bias signal supplied to the substrate support 11 may be a bias DC signal including voltage pulses supplied by the bias DC generation unit 32a, instead of the bias RF signal supplied by the second RF generation unit 31b. In this case, the bias DC signal may include voltage pulses of 2kV (RMS) or higher. The bias DC signal may include voltage pulses of 3kV or higher. The bias DC signal may include voltage pulses of 20kV or lower.

[0047] After a predetermined time has elapsed, the supply of the source RF signal and bias signal, the supply of the processing gas, etc., are stopped, and etching of the carbon-containing film 131 is completed. Subsequently, the substrate W is lifted by a lifter, handed over to a transport arm, and removed from the chamber 10. This completes the plasma processing method.

[0048] According to this exemplary embodiment, the plasma processing method controls the temperature of the substrate support 11 with a refrigerant set to a target temperature of -70°C to 100°C during plasma etching, while supplying a high-source RF signal of 2kW or more to the antenna 14 and a high-bias RF signal with a power of 2kW or more, or a high-bias DC signal including a voltage pulse of 2kV or more, to the substrate support 11. Then, plasma is generated from the processing gas and the carbon-containing film 131 is etched. As a result, the etched processing shape is improved and a high etching rate is achieved. This plasma processing method can be used for deep hole drilling with a high aspect ratio.

[0049] <Examples> Using the plasma processing apparatus described above, etching was performed under the following two etching conditions, A and B. During plasma etching under conditions A and B, the substrate or substrate support was controlled by the refrigerant temperature to achieve the same target temperature. The film to be etched was a carbon-containing film M2 having a silicon-containing mask M1 on its surface.

[0050] Condition A: Source RF signal: 2000W Bias signal: 1850W Refrigerant temperature: 0℃ Processing time: 4 min

[0051] Condition B: Source RF signal: 4500W Bias signal: 4000W Refrigerant temperature: -60℃ Processing time: 4 min Condition B satisfies the conditions of this plasma processing method.

[0052] Figure 4 shows the etched film after etching under conditions A and B. The top of Figure 4 shows a magnified view of the upper part of the etched film, and the bottom of Figure 4 shows an overall view of the etched film. In etching under condition B, the etching depth C of the recess Q was deeper and the hole width D of the recess Q was narrower than in etching under condition A. In condition A, the etching rate was 293 nm / min and the hole width D of the bowing portion was 95 nm. In condition B, the etching rate was 607 nm / min and the hole width D was 74 nm. In condition B, it can be confirmed that the vertical shape of the recess Q was improved and a higher etching rate was obtained.

[0053] <Other exemplary embodiments of this plasma processing method> Figure 5 is a schematic diagram showing an example of the configuration of the plasma processing apparatus 1 in which the plasma processing method of this exemplary embodiment is carried out.

[0054] In one embodiment, the plasma processing apparatus 1 further includes a temperature sensor 150. In one embodiment, the temperature sensor 150 is an optical interference thermometer and is positioned above the dielectric window 50. The temperature sensor 150 can measure the temperature of the substrate W non-contact by irradiating light onto the substrate W on the substrate support 11 and receiving the reflected light. The measurement result of the temperature sensor 150 is output to the control unit 2, and the control unit 2 can adjust the temperature of the substrate W by controlling the source RF signal supplied to the antenna 14, the bias signal supplied to the substrate support 11, and the set temperature of the refrigerant supplied to the substrate support 11. The other components of the plasma processing apparatus 1 are as described above.

[0055] In one embodiment of this plasma processing method, during the plasma generation step S4, the temperature of the substrate W on the substrate support 11 is measured by a temperature sensor 150. Based on the temperature measurement result, at least one of the source RF signal, bias signal, and refrigerant set temperature is controlled. This adjusts the temperature of the substrate W on the substrate support 11. In one embodiment, if the temperature of the substrate W measured by the temperature sensor 150 is lower than, for example, the target temperature, the source RF signal and bias signal are increased, and the refrigerant set temperature is increased. If the temperature of the substrate W measured by the temperature sensor 150 is higher than the target temperature, the source RF signal and bias signal are decreased, and the refrigerant set temperature is decreased. The target temperature of the substrate W may be calculated from a correlation between the temperature of the substrate W and the etching processing shape and etching rate, which have been determined in advance, or it may be calculated by analysis software, or it may be arbitrarily determined by the user. Furthermore, the measurement of the substrate W temperature by the temperature sensor 150 may be performed continuously, intermittently, or one or more predetermined times during the plasma generation step S4. The other steps of this plasma processing method are as described above.

[0056] According to this exemplary embodiment, the temperature of the substrate W during the plasma generation process S4 is brought closer to the target temperature. That is, the balance between the heat input to the substrate W due to the high-source RF signal and high-bias signal and the heat removal by the cryogenic coolant is appropriately adjusted. As a result, the etched shape is further improved, and an even higher etching rate can be obtained.

[0057] In this exemplary embodiment, the temperature of the substrate support 11 may be measured by the temperature sensor 150. In this case, at least one of the source RF signal, bias signal, and refrigerant set temperature is controlled based on the measurement result of the temperature of the substrate support 11. This adjusts the temperature of the substrate W on the substrate support 11, or the temperature of the substrate support 11. Furthermore, the temperatures of both the substrate W and the substrate support 11 may be measured, and the temperature of the substrate W or the substrate support 11 may be adjusted based on the measured temperatures.

[0058] <Other exemplary embodiments of this plasma processing method> In high-aspect-ratio deep hole drilling, it is desirable for the hole to have a sufficiently vertical shape while also having a bottom shape that is close to a perfect circle. Therefore, in the plasma processing method of this exemplary embodiment, the temperature of at least one of the substrate W or the substrate support part 11 is adjusted in the plasma generation step S4. Note that the temperature of the substrate W or the substrate support part 11 is related to the amount of heat entering and leaving the substrate W (the sum of heat input and heat removal).

[0059] Figure 6 is a flowchart showing an example of the plasma generation process in this exemplary embodiment. In one embodiment, the plasma generation process S4 includes a step S4-1 for adjusting the temperature of the substrate W to a first temperature (low) and a step S4-2 for adjusting the temperature of the substrate W to a second temperature (high) that is higher than the first temperature. In one embodiment, the first temperature (low) is 40°C or less, and the second temperature (high) is 40°C or higher. This adjustment of the substrate W temperature includes not only cases where the temperature of the substrate W is actually adjusted to the first or second temperature, but also cases where the temperature of the substrate W is adjusted to approach the first or second temperature. In one embodiment, the temperature of the substrate support 11 may be adjusted instead of the temperature of the substrate W, or both the temperature of the substrate W and the temperature of the substrate support 11 may be adjusted. In addition, in the plasma generation step S4 of this exemplary embodiment, the temperature of the substrate support part 11 is controlled by a refrigerant set to be between -70°C and 100°C during plasma etching, while a high-source RF signal of 2kW or more is supplied to the antenna 14, and a high-bias RF signal of 2kW or more, or a high-bias DC signal of a voltage pulse of 2kV or more is supplied to the substrate support part 11.

[0060] In one embodiment, steps S4-1 and S4-2 are performed in this order. In one embodiment, steps S4-1 and S4-2 are repeated alternately a predetermined number of times. The predetermined number of times may be one or more. In one embodiment, steps S4-1 and S4-2 may be performed in the reverse order, that is, step S4-2 is performed first, followed by step S4-1. Then, steps S4-1 and S4-2 may be repeated alternately in this order a predetermined number of times.

[0061] In one embodiment, steps S4-1 and S4-2 (temperature adjustment of the substrate W or substrate support part 11) are performed by the following controls 1 to 5.

[0062] In step S4-1, a bias signal of the first output is supplied to the substrate support unit 11, and in step S4-2, a bias signal of the second output, which is greater than the first output, is supplied to the substrate support unit 11 (control 1). In one embodiment, the output of the bias signal is adjusted by a second RF generation unit 31b or a bias DC generation unit 32a.

[0063] In step S4-1, a bias signal with a first duty cycle is supplied to the substrate support unit 11, and in step S4-2, a bias signal with a second duty cycle greater than the first duty cycle is supplied to the substrate support unit 11 (control 2). The second duty cycle is such that the bias signal (bias power) is higher than that of the first duty cycle. The period of the pulse wave of the bias signal has a period of high pulse level and a period of low pulse level. The duty cycle of the bias signal is the proportion of the period of high level in the period of the pulse wave. In one embodiment, the duty cycle of the bias signal is adjusted by the second RF generation unit 31b or the bias DC generation unit 32a.

[0064] In step S4-1, a bias signal of a first frequency is supplied to the substrate support unit 11, and in step S4-2, a bias signal of a second frequency lower than the first frequency is supplied to the substrate support unit 11 (control 3). In one embodiment, the frequency of the bias signal is adjusted by a second RF generation unit 31b or a bias DC generation unit 32a.

[0065] In one embodiment, during the plasma generation process S4, a heat transfer gas is supplied between the substrate W and the substrate support 11 by the heat transfer gas supply unit 100. In process S4-1, a heat transfer gas at a first pressure is supplied between the substrate W and the substrate support 11, and in process S4-2, a heat transfer gas at a second pressure lower than the first pressure is supplied between the substrate W and the substrate support 11 (control 4). In one embodiment, the supply pressure of the heat transfer gas is adjusted by the heat transfer gas supply unit 100.

[0066] In step S4-1, the temperature of the refrigerant controlling the temperature of the substrate support section 11 is set to a first temperature, and in step S4-2, the temperature of the refrigerant is set to a second temperature higher than the first temperature (control 5). In one embodiment, the set temperature of the refrigerant is adjusted by the temperature adjustment section 80.

[0067] In one embodiment, one of the controls 1 to 5 is performed. In another embodiment, multiple controls 1 to 5 are performed.

[0068] Figure 7 illustrates the relationship between substrate temperature and etching shape. When the plasma generation process is performed at a constant high temperature (H) (high heat input / output to the substrate), the bottom shape BT of the etched recess Q tends to approach a perfect circle, but the width D of some holes widens, and the vertical shape of the recess Q tends to decrease. On the other hand, when the plasma generation process is performed at a constant low temperature (L) (small heat input / output to the substrate), the widening of the hole width D decreases, and the vertical shape of the hole tends to improve, but the bottom shape BT of the recess Q tends to move away from a perfect circle. By performing a plasma generation process S4 that combines a first temperature (H) and a second temperature (L), as in this plasma processing method, it is possible to make the etched recess Q have a sufficient vertical shape while having a bottom shape BT that is close to a perfect circle.

[0069] In this exemplary embodiment, steps S4-1 and S4-2 may not be repeated, but performed once each. One step S4-1 and one step S4-2 may be defined as one set, and this set may be performed once or multiple times, after which step S4-1 may be performed one last time. In one embodiment, steps S4-1 and S4-2 may be performed alternately in this order, with step S4-1 being performed last.

[0070] The plasma processing method and plasma processing apparatus can be modified in various ways without departing from the scope and spirit of this disclosure. For example, some components of one embodiment can be added to other embodiments within the ordinary creative ability of a person skilled in the art. Also, some components of one embodiment can be replaced with corresponding components of other embodiments. [Explanation of Symbols]

[0071] 1...Plasma processing apparatus, 2...Control unit, 10...Chamber, 11...Substrate support unit, 13...Gas introduction unit, 14...Antenna, 31a...First RF generation unit, 31b...Second RF generation unit, 32a...Bias DC generation unit, 80...Temperature control unit, 131...Carbon-containing film, 132...Silicon-containing mask, W...Substrate

Claims

1. A plasma processing method performed in an inductively coupled plasma processing apparatus having a chamber, (a) A step of providing a substrate having a carbon-containing film and a silicon-containing mask formed on the carbon-containing film onto a substrate support portion in a chamber, (b) A step of supplying a refrigerant to the substrate support to control the temperature of the substrate support, (c) A step of supplying a processing gas into the chamber, (d) While step (b) is being performed, a step is to generate plasma from the processing gas in the chamber using a source RF signal and to supply a bias signal to the substrate support to etch the carbon-containing film, In step (d) above, the refrigerant in step (b) above is set so that the substrate or substrate support portion during plasma etching is at a target temperature of -70°C or higher and 100°C or lower. The source RF signal in step (d) above is an RF signal having a power of 2 kW or more. The bias signal in step (d) above is a bias RF signal having a power of 2 kW or more, or a bias DC signal including a voltage pulse of 2 kV or more. Plasma treatment method.

2. (e) A step of measuring the temperature of at least one of the substrate or the substrate support portion using a temperature sensor, (f) The step of adjusting the temperature of at least one of the substrate or the substrate support by controlling at least one of the source RF signal in (d), the bias signal in (d), and the set temperature of the refrigerant in (b) based on the temperature measured in (e), The plasma treatment method according to claim 1.

3. The above (d) is, (d1) A step of adjusting the temperature of at least one of the substrate or the substrate support to a first temperature, (d2) A step of adjusting the temperature of at least one of the substrate or the substrate support to a second temperature higher than the first temperature, The plasma treatment method according to claim 1 or 2.

4. The above (d1) and (d2) are performed in this order. The plasma treatment method according to claim 3.

5. The above (d) is, The process further includes alternating between the steps described in (d1) and (d2), The plasma treatment method according to claim 3 or 4.

6. The above (d1) and (d2) each have at least one of the following steps: (g), (h), (i), (j), (k) (g) is a step in which, in (d1), a bias signal of a first output is supplied to the substrate support, and in (d2), a bias signal of a second output greater than the first output is supplied to the substrate support. (h) is a step in which, in (d1), a bias signal with a first duty cycle is supplied to the substrate support, and in (d2), a bias signal with a second duty cycle greater than the first duty cycle is supplied to the substrate support. (i) is the step of supplying a bias signal of a first frequency to the substrate support in (d1), and supplying a bias signal of a second frequency lower than the first frequency to the substrate support in (d2), (j) is a step in which, in (d1), a heat transfer gas at a first pressure is supplied between the substrate and the substrate support, and in (d2), a heat transfer gas at a second pressure which is lower than the first pressure is supplied between the substrate and the substrate support. (k) is a step in which, in (d1), the temperature of the refrigerant is set to a first temperature, and in (d2), the temperature of the refrigerant is set to a second temperature that is higher than the first temperature. The plasma treatment method according to any one of claims 3 to 5.

7. The aforementioned processing gas includes an oxygen-containing gas and a sulfur-containing gas. A plasma treatment method according to any one of claims 1 to 6.

8. The source RF signal has a frequency of 13 MHz or higher. A plasma treatment method according to any one of claims 1 to 7.

9. The bias signal in step (d) is a bias RF signal having a power of 2 kW or more, The bias RF signal has a frequency of 13 MHz or less. A plasma treatment method according to any one of claims 1 to 8.

10. The carbon-containing film includes an amorphous carbon film. A plasma treatment method according to any one of claims 1 to 9.

11. The aforementioned silicon-containing mask includes a silicon oxide nitride film. A plasma treatment method according to any one of claims 1 to 10.

12. An inductively coupled plasma processing apparatus having a chamber, A substrate support portion is provided within the chamber and supports a substrate having a carbon-containing film and a silicon-containing mask formed on the carbon-containing film, A temperature adjustment unit that supplies a refrigerant to the substrate support unit to adjust the temperature of the substrate support unit, A processing gas supply unit that supplies processing gas into the chamber, A source RF signal generation unit that generates a source RF signal, A bias signal supply unit that supplies a bias signal to the substrate support unit, It comprises a control unit and, The control unit, (a) With the substrate provided on the substrate support portion in the chamber, (b) The temperature control unit supplies a refrigerant to the substrate support unit to control the temperature of the substrate support unit, (c) The processing gas supply unit supplies the processing gas into the chamber, (d) While (b) is being performed, plasma is generated from the processing gas in the chamber by the source RF signal generated by the source RF signal generation unit, and a bias signal is supplied to the substrate support unit by the bias signal supply unit to etch the carbon-containing film. In (d) above, the refrigerant in (b) above is set so that the substrate or substrate support portion during plasma etching reaches a target temperature of -70°C to 100°C. The source RF signal in step (d) above is an RF signal having a power of 2 kW or more. The bias signal in step (d) above is a bias RF signal having a power of 2 kW or more, or a bias DC signal including a voltage pulse of 2 kV or more. Execute control Plasma processing equipment.

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