TW202245056A - Substrate processing method and substrate processing apparatus in which a plasma is generated from a reactant gas including HF and CxHyFz for etching a dielectric film on a substrate - Google Patents

Abstract

In an illustrative embodiment, a substrate processing method is provided. The substrate processing method includes the following steps: preparing a substrate having a dielectric film on a substrate supporting device inside a chamber; and generating a plasma from a reactant gas including HF gas and at least one CxHyFz gas selected from a group including C4H2F6 gas, C4H2F8 gas, C3H2F4 gas and C3H2F6 to carry out etching on the dielectric film, wherein in the etching step, the temperature of the substrate supporting device is set to be below 0 DEG C, and the flow rate of the HF gas is more than the flow rate of the CxHyFz gas. The flow rate of the CxHyFz gas is below 20vol% with respect to a total flow rate of the reactant gas. The flow rate of the HF gas is above 70vol% with respect to the total flow rate of the reactant gas.

Description

Substrate processing method and substrate processing device

Exemplary embodiments of the present invention relate to a substrate processing method and a substrate processing apparatus.

For example, Patent Document 1 describes a technique of etching a silicon oxide film. prior art literature patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2016-122774

[Problem to be solved by the invention]

The present invention provides a technique for improving the etching selectivity of a dielectric film for mask etching. [Technical means to solve the problem]

In an exemplary embodiment of the present invention, a substrate processing method is provided, which includes the following steps: preparing a substrate with a dielectric film on a substrate holder in a chamber; and self _- contained _HF gas and The reaction gas of at least one C _x H _y F _z gas in the group consisting of F ₆ gas, C ₄ H ₂ F ₈ gas, C ₃ H ₂ F ₄ gas and C ₃ H ₂ F ₆ gas generates plasma, Etching the above-mentioned dielectric film; and in the above-mentioned etching process, the temperature of the above-mentioned substrate holder is set below 0° C., and the flow rate of the above-mentioned HF gas is greater than the flow rate of the above-mentioned C _x H _y F _z gas. [Effect of Invention]

According to an exemplary embodiment of the present invention, it is possible to provide a technique for improving the etching selectivity of a dielectric film for mask etching.

Hereinafter, various embodiments of the present invention will be described.

In an exemplary embodiment, a substrate processing method is provided. _The substrate processing method includes the following steps: preparing a substrate with a dielectric film _on a _{substrate holder} in _{a chamber ;} The reaction gas of at least one C _x H _y F _z gas in the group consisting of ₂ F ₄ gas and C ₃ H ₂ F ₆ gas generates plasma to etch the dielectric film; in the etching process, the substrate holder The temperature is set below 0°C, and the flow rate of the HF gas is greater than that of the above-mentioned C _x H _y F _z gas.

In an exemplary embodiment, the flow rate of the C _x H _y F _z gas relative to the total flow rate of the reaction gas is 20% by volume or less.

In an exemplary embodiment, the flow rate of the HF gas is more than 70% by volume relative to the total flow rate of the reaction gas.

In an exemplary embodiment, the reaction gas further includes a halogen-containing gas.

In an exemplary embodiment, the halogen-containing gas system is at least one selected from the group consisting of chlorine-containing gas, bromine-containing gas, and iodine-containing gas.

In an exemplary embodiment, the gas system containing halogen is selected from Cl ₂ , SiCl ₂ , SiCl ₄ , CCl ₄ , SiH ₂ Cl ₂ , Si ₂ Cl ₆ , CHCl ₃ , SO ₂ Cl ₂ , BCl ₃ , PCl ₃ , PCl ₅ , POCl ₃ , Br ₂ , HBr, CBr ₂ F ₂ , C ₂ F ₅ Br, PBr ₃ , PBr ₅ , POBr ₃ , BBr ₃ , HI, CF ₃ I, C ₂ F ₅ I, C ₃ F ₇ At least one gas from the group consisting of I, IF ₅ , IF ₇ , I ₂ and PI ₃ .

In an exemplary embodiment, the reaction gas includes a phosphorus-containing gas.

In an exemplary embodiment, the reaction gas includes an oxygen-containing gas.

In an exemplary embodiment, the reaction gas further includes at least one selected from the group consisting of boron-containing gas and sulfur-containing gas.

In an exemplary embodiment, a plasma is generated from a process gas comprising a reactive gas and an inert gas.

In an exemplary embodiment, the dielectric film is a silicon-containing film.

In an exemplary embodiment, the silicon-containing film includes at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, and a polysilicon film.

In one exemplary embodiment, the substrate has a mask defining at least one opening in the dielectric film and comprising an organic film or a metal-containing film.

In an exemplary embodiment, the etching process includes a step of applying an electrical bias to the substrate holder, and the period of applying the electrical bias to the substrate holder includes a first period and a second period alternately with the above-mentioned first period. The electrical bias voltage in the first period is 0 or the first level, and the electrical bias voltage in the second period is the second level greater than the first level.

In one exemplary embodiment, the etching step includes supplying high-frequency power for generating plasma to the substrate holder or the upper electrode facing the substrate holder, and the period of supplying the high-frequency power includes the third period and the second period. In the fourth period in which the three periods alternate, the level of the high-frequency power in the third period is 0 or the third level, and the level of the high-frequency power in the fourth period is the fourth level greater than the third level, and the level of the high-frequency power in the third period The 2nd period and the 4th period overlap at least a part.

In an exemplary embodiment, the electrical bias is a pulsed voltage.

In an exemplary embodiment, the etching step includes a step of supplying a DC voltage or low-frequency power to an upper electrode facing the substrate holder.

In an exemplary embodiment, the etching step includes: a first step of setting the inside of the chamber to a first pressure, supplying a first electrical bias to the substrate holder to etch the dielectric film; and a second step, It sets the chamber as the second pressure, supplies the second electrical bias to the substrate holder to etch the dielectric film; and the first pressure is different from the second pressure and/or the first electrical bias is different from the second electrical bias. The bias voltage is different.

In an exemplary embodiment, the first pressure is greater than the second pressure.

In an exemplary embodiment, the absolute value of the magnitude of the first electrical bias is greater than the absolute value of the magnitude of the second electrical bias.

In one exemplary embodiment, the first step and the second step are alternately repeated.

In an exemplary embodiment, a substrate processing method is provided. The substrate processing method includes the following steps: preparing a substrate having a _silicon -containing film including a _silicon oxide _film on a substrate holder in a chamber; gas, x is an integer of 2 or more, y and z are an integer of 1 or more) the reaction gas generates plasma to etch the silicon-containing film; and in the etching process, the temperature of the substrate holder is set below 0°C, C The flow rate of the _x H _y F _z gas is 20% by volume or less relative to the total flow rate of the reaction gas.

In an exemplary embodiment, the fluorine-containing gas system can generate gas of HF species in the chamber.

In an exemplary embodiment, the C _x H _y F _z gas has more than one CF ₃ group.

In an exemplary embodiment, the C _x H _y F _z gas comprises a gas selected from C ₃ H ₂ F ₄ gas, C ₃ H ₂ F ₆ gas, C ₄ H ₂ F ₆ gas, C ₄ H ₂ F ₈ gas and At least one of the group consisting of C ₅ H ₂ F ₆ gases.

In an exemplary embodiment, among the reaction gases, the flow rate of the fluorine-containing gas is the largest.

In an exemplary embodiment, a substrate processing method is provided. The substrate processing method includes the steps of: preparing a substrate having a silicon-containing film including a silicon oxide film on a substrate holder in a chamber; generating plasma in the chamber; and using HF species and C _x H _y F contained in the plasma The species _z (x is an integer greater than 2, and y and z are integers greater than 1) etches the silicon-containing film; and the amount of HF species in the plasma is the largest.

In an exemplary embodiment, a substrate processing apparatus is provided. The substrate processing apparatus includes a chamber, a substrate holder installed in the chamber and configured to be capable of adjusting temperature, a plasma generation unit that supplies power for generating plasma in the chamber, and a control unit. The control unit controls the substrate holder The dielectric film of the substrate supported on the substrate is etched to perform the following control, that is, by the power supplied from the plasma generating part, the gas containing HF and the gas selected from C ₄ H ₂ F ₆ , C ₄ H ₂ F ₈ The reaction gas of at least one C _x H _y F _z gas in the group consisting of gas, C ₃ H ₂ F ₄ gas and C ₃ H ₂ F ₆ gas is introduced into the chamber to generate plasma, and under control, The temperature of the substrate holder is set below 0°C, and the flow rate of HF gas is higher than that of C _x H _y F _z gas.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code|symbol is attached|subjected to the same or similar element in each figure, and the description which overlaps is abbreviate|omitted. Unless otherwise specified, positional relationships such as up, down, left, and right will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent the actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

<Structure of Substrate Processing Apparatus 1> FIG. 1 is a diagram schematically showing a substrate processing apparatus 1 according to an exemplary embodiment. A substrate processing method according to an exemplary embodiment (hereinafter referred to as “this processing method”) can be executed using the substrate processing apparatus 1 .

A substrate processing apparatus 1 shown in FIG. 1 includes a chamber 10 . The chamber 10 provides an internal space 10s therein. The chamber 10 includes a chamber body 12 . The chamber body 12 has a substantially cylindrical shape. The chamber body 12 is formed of aluminum, for example. A corrosion-resistant film is provided on the inner wall of the chamber body 12 . The corrosion-resistant film can be formed of ceramics such as alumina and yttrium oxide.

A passage 12p is formed on the side wall of the chamber body 12 . The substrate W is conveyed between the internal space 10s and the outside of the chamber 10 through the passage 12p. The passage 12p is opened and closed by a gate valve 12g. The gate valve 12g is disposed along the side wall of the chamber body 12 .

A supporting portion 13 is disposed on the bottom of the chamber body 12 . The support portion 13 is formed of an insulating material. The support portion 13 has a substantially cylindrical shape. The supporting portion 13 extends upward from the bottom of the chamber body 12 in the inner space 10s. The supporting portion 13 supports the substrate holder 14 . The substrate holder 14 is configured to support the substrate W in the inner space 10s.

The substrate holder 14 has a lower electrode 18 and an electrostatic chuck 20 . The substrate holder 14 may in turn have an electrode plate 16 . The electrode plate 16 is formed of a conductor such as aluminum, and has a substantially disc shape. The lower electrode 18 is disposed on the electrode plate 16 . The lower electrode 18 is formed of a conductor such as aluminum and has a substantially disc shape. The lower electrode 18 is electrically connected to the electrode plate 16 .

The electrostatic chuck 20 is disposed on the lower electrode 18 . The substrate W is placed on the upper surface of the electrostatic chuck 20 . The electrostatic chuck 20 has a body and electrodes. The body of the electrostatic chuck 20 has a substantially disc shape and is formed of a dielectric. The electrode of the electrostatic chuck 20 is a film electrode, which is arranged in the body of the electrostatic chuck 20 . Electrodes of the electrostatic chuck 20 are connected to a DC power source 20p via a switch 20s. When the voltage from the DC power supply 20 p is applied to the electrodes of the electrostatic chuck 20 , an electrostatic attractive force is generated between the electrostatic chuck 20 and the substrate W. The substrate W is attracted to the electrostatic chuck 20 by its electrostatic attraction, and is held by the electrostatic chuck 20 .

An edge ring 25 is disposed on the substrate holder 14 . The edge ring 25 is an annular member. The edge ring 25 can be formed of silicon, silicon carbide, or quartz. The substrate W is disposed on the electrostatic chuck 20 and in a region surrounded by the edge ring 25 .

Inside the lower electrode 18, a flow path 18f is provided. To the flow path 18f, a heat exchange medium (for example, refrigerant) is supplied from a cooler unit provided outside the chamber 10 through a pipe 22a. The heat exchange medium supplied to the flow path 18f returns to the cooler unit through the pipe 22b. In the substrate processing apparatus 1 , the temperature of the substrate W placed on the electrostatic chuck 20 is adjusted by heat exchange between the heat exchange medium and the lower electrode 18 .

A gas supply line 24 is provided in the substrate processing apparatus 1 . The gas supply line 24 supplies heat transfer gas (for example, He gas) from the heat transfer gas supply mechanism to the gap between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

The substrate processing apparatus 1 further includes an upper electrode 30 . The upper electrode 30 is disposed above the substrate holder 14 . The upper electrode 30 is supported on the upper part of the chamber body 12 via a member 32 . The member 32 is formed of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the chamber body 12 .

The upper electrode 30 may include a top plate 34 and a support 36 . The lower surface of the top plate 34 is the lower surface on the side of the inner space 10s, and defines the inner space 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor that generates less Joule heat. The top plate 34 has a plurality of gas ejection holes 34a penetrating through the top plate 34 along its plate thickness direction.

The support body 36 supports the top plate 34 in a detachable manner. The support body 36 is formed of a conductive material such as aluminum. Inside the support body 36, a gas diffusion chamber 36a is provided. The support body 36 has a plurality of air holes 36b extending downward from the gas diffusion chamber 36a. The plurality of gas holes 36b communicate with the plurality of gas ejection holes 34a, respectively. A gas introduction port 36c is formed in the support body 36 . The gas introduction port 36c is connected to the gas diffusion chamber 36a. The gas supply pipe 38 is connected to the gas introduction port 36c.

A gas source group 40 is connected to the gas supply pipe 38 via a flow controller group 41 and a valve group 42 . The flow controller group 41 and the valve group 42 constitute a gas supply unit. The gas supply unit may further include a gas source group 40 . The gas source group 40 includes a plurality of gas sources. The plurality of gas sources includes sources of process gases used in the present process. The flow controller group 41 includes a plurality of flow controllers. The plurality of flow controllers in the flow controller group 41 are respectively mass flow controllers or pressure-controlled flow controllers. The valve group 42 includes a plurality of on-off valves. A plurality of gas sources of the gas source group 40 are respectively connected to the gas supply pipe 38 through the corresponding flow controllers of the flow controller group 41 and the corresponding on-off valves of the valve group 42 .

In the substrate processing apparatus 1 , a shield 46 is detachably provided along the inner wall surface of the chamber body 12 and the outer periphery of the support portion 13 . Shield 46 prevents reaction by-products from adhering to chamber body 12 . The shield 46 is formed, for example, by forming a corrosion-resistant film on the surface of a base material made of aluminum. The corrosion-resistant film can be formed of ceramics such as yttrium oxide.

A baffle 48 is disposed between the support portion 13 and the sidewall of the chamber body 12 . The baffle 48 is constituted by, for example, forming a corrosion-resistant film (a film of yttrium oxide or the like) on the surface of a member made of aluminum. A plurality of through holes are formed in the baffle plate 48 . An exhaust port 12e is disposed below the baffle plate 48 and at the bottom of the chamber body 12 . An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52 . The exhaust device 50 includes a pressure regulating valve and a vacuum pump such as a turbomolecular pump.

The substrate processing apparatus 1 includes a high-frequency power source 62 and a bias power source 64 . The high-frequency power supply 62 is a power supply that generates high-frequency power HF. The high-frequency power HF has a first frequency suitable for generating plasma. The first frequency is, for example, a frequency within a range of 27 MHz to 100 MHz. The high-frequency power source 62 is connected to the lower electrode 18 via a matching unit 66 and the electrode plate 16 . The matching unit 66 has a circuit for matching the impedance of the load side (lower electrode 18 side) of the high-frequency power supply 62 with the output impedance of the high-frequency power supply 62 . Furthermore, the high-frequency power supply 62 may also be connected to the upper electrode 30 via a matching unit 66 . The high-frequency power supply 62 constitutes an example of a plasma generation unit.

The bias power supply 64 is a power supply for generating electrical bias voltage. The bias power supply 64 is electrically connected to the lower electrode 18 . The electrical bias has a second frequency. The second frequency is lower than the first frequency. The second frequency is, for example, a frequency within a range of 400 kHz to 13.56 MHz. When the electric bias is used together with high-frequency power HF, it is given to the substrate holder 14 so that ions are fed into the substrate W. In one example, an electrical bias is applied to the lower electrode 18 . When an electrical bias is applied to the lower electrode 18, the electrical position of the substrate W placed on the substrate holder 14 fluctuates within a period specified by the second frequency. Furthermore, an electrical bias can also be applied to the bias electrodes disposed in the electrostatic chuck 20 .

In one embodiment, the electric bias voltage may be high-frequency electric power LF having the second frequency. When the high-frequency power LF is used together with the high-frequency power HF, it is used as a high-frequency bias power for feeding ions into the substrate W. A bias power supply 64 configured to generate high-frequency power LF is connected to the lower electrode 18 via a matching unit 68 and the electrode plate 16 . The matching unit 68 has a circuit for matching the impedance of the load side (lower electrode 18 side) of the bias power supply 64 with the output impedance of the bias power supply 64 .

In addition, instead of using high-frequency power HF, high-frequency power LF may be used, that is, only a single high-frequency power may be used to generate plasma. In this case, the frequency of the high-frequency power LF may be greater than 13.56 MHz, for example, 40 MHz. In addition, in this case, the substrate processing apparatus 1 does not have to include the high-frequency power supply 62 and the matching unit 66 . In this case, the bias power supply 64 constitutes an example of a plasma generation unit.

In another embodiment, the electrical bias voltage can also be a pulsed voltage (pulse voltage). In this case, the bias power supply can be a DC power supply. The bias power supply may be configured to supply a pulse voltage to the power supply itself, or may be configured to include a device for making a voltage pulse on the downstream side of the bias power supply. In one example, a pulse voltage is applied to the lower electrode 18 so as to generate a negative potential on the substrate W. As shown in FIG. The pulse voltage can be a rectangular wave, a triangular wave, a pulse wave, or other waveforms.

The period of the pulse voltage is specified by the second frequency. The cycle of the pulse voltage includes two periods. The pulse voltage in one of the two periods is a negative polarity voltage. The voltage level (ie, the absolute value) of one of the two periods is higher than the voltage level (ie, the absolute value) of the other period of the two periods. The voltage in the other period can be either negative polarity or positive polarity. The voltage level of the negative polarity in another period can be greater than zero or zero. In this embodiment, the bias power supply 64 is connected to the lower electrode 18 via a low-pass filter and the electrode plate 16 . Moreover, the bias power supply 64 can also be connected to the bias electrode provided in the electrostatic chuck 20 instead of the lower electrode 18 .

In one embodiment, the bias power supply 64 may also apply a continuous wave electric bias voltage to the lower electrode 18 . That is, the bias power supply 64 may continuously apply an electrical bias to the lower electrode 18 .

In another embodiment, the bias power supply 64 can also apply the pulse wave of electrical bias to the lower electrode 18 . A pulse wave of an electrical bias can be periodically applied to the lower electrode 18 . The period of the pulse wave of the electrical bias is specified by the third frequency. The third frequency is lower than the second frequency. The third frequency is, for example, not less than 1 Hz and not more than 200 kHz. In another example, the third frequency may be not less than 5 Hz and not more than 100 kHz.

The period of the pulse wave of the electrical bias includes two periods, ie, the H period and the L period. The level of the electrical bias voltage (ie, the level of the pulse of the electrical bias voltage) in the H period is higher than the level of the electrical bias voltage in the L period. That is, the pulse wave of the electrical bias can also be given to the lower electrode 18 by increasing or decreasing the level of the electrical bias. The level of the electrical bias voltage during the L period can also be greater than zero. Alternatively, the level of the electrical bias voltage during the L period can also be zero. That is, the pulse wave of the electrical bias can also be applied to the lower electrode 18 by alternately switching the supply and stop of the electrical bias to the lower electrode 18 . Here, when the electric bias voltage is the high-frequency power LF, the level of the electric bias voltage is the power level of the high-frequency power LF. In the case where the electrical bias is high-frequency power LF, the level of high-frequency power LF in the pulse of the electrical bias may be 2 kW or more. When the electrical bias is a pulse wave of a negative DC voltage, the level of the electrical bias is the effective value of the absolute value of the negative DC voltage. The duty ratio of the pulse wave of the electrical bias, that is, the ratio of the H period to the period of the pulse wave of the electrical bias, is, for example, 1% or more and 80% or less. In another example, the duty ratio of the pulse wave of the electrical bias may be not less than 5% and not more than 50%. Alternatively, the duty ratio of the pulse wave of the electrical bias may be 50% or more and 99% or less. In addition, in the period during which the electric bias voltage is supplied, the L period corresponds to the above-mentioned first period, and the H period corresponds to the above-mentioned second period. Also, the level of the electrical bias voltage in the L period corresponds to the above-mentioned 0 or 1st level, and the level of the electrical bias voltage in the H period corresponds to the above-mentioned second level.

In one embodiment, the high-frequency power supply 62 may also supply a continuous wave of high-frequency power HF. That is, the high-frequency power supply 62 may continuously supply high-frequency power HF.

In another embodiment, the high-frequency power supply 62 may also supply pulse waves of high-frequency power HF. Pulse waves of high-frequency power HF can be supplied periodically. The period of the pulse wave of high-frequency power HF is specified by the fourth frequency. The fourth frequency is lower than the second frequency. In one embodiment, the fourth frequency is the same as the third frequency. The cycle of the pulse wave of high-frequency power HF includes two periods, that is, the H period and the L period. The power level of the high-frequency power HF in the H period is higher than the power level of the high-frequency power HF in the L period of the two periods. The power level of the high-frequency power HF during the L period may be greater than zero or zero. In addition, in the period during which the high-frequency power HF is supplied, the L period corresponds to the above-mentioned third period, and the H period corresponds to the above-mentioned fourth period. Also, the level of the high-frequency power HF in the L period corresponds to the above-mentioned 0 or the third level, and the level of the electric bias voltage in the H period corresponds to the above-mentioned fourth level.

Furthermore, the period of the pulse wave of the high-frequency power HF may also be synchronized with the period of the pulse wave of the electrical bias voltage. The H period in the cycle of the pulse wave of the high-frequency power HF may also be synchronized with the H period in the cycle of the pulse wave of the electrical bias voltage. Alternatively, the H period in the cycle of the pulse wave of the high-frequency power HF may not be synchronized with the H period in the cycle of the pulse wave of the electrical bias voltage. The time length of the H period in the cycle of the pulse wave of the high-frequency power HF may be the same as or different from the time length of the H period in the cycle of the pulse wave of the electric bias voltage. Part or all of the H period in the cycle of the pulse wave of the high-frequency power HF may overlap with the H period in the cycle of the pulse wave of the electrical bias voltage.

Fig. 2 is a timing chart showing an example of high-frequency power HF and electric bias. Figure 2 is an example of using pulse waves for both high-frequency power HF and electrical bias. In FIG. 2, the horizontal axis represents time. In FIG. 2 , the vertical axis represents the electric power levels of the high-frequency electric power HF and the electric bias voltage. "L1" of the high-frequency power HF indicates that the high-frequency power HF is not supplied or is lower than the power level indicated by "H1". "L2" of the electrical bias indicates that no electrical bias is supplied or is lower than the power level indicated by "H2". When the electrical bias is a pulse wave of a negative DC voltage, the level of the electrical bias is the effective value of the absolute value of the negative DC voltage. Furthermore, the power levels of the high-frequency power HF and the electrical bias voltage in FIG. 2 do not represent the relative relationship between the two, and can be set arbitrarily. Figure 2 shows that the cycle of the pulse wave of high-frequency power HF is synchronized with the cycle of the pulse wave of electrical bias, and the time length of the H period and L period of the pulse wave of high-frequency power HF is the same as the H period and period of the pulse wave of electrical bias. An example where the length of the L period is the same.

Return to FIG. 1 to continue the description. The substrate processing apparatus 1 further includes a power supply 70 . The power source 70 is connected to the upper electrode 30 . In one example, the power supply 70 may be configured to supply a DC voltage or low-frequency power to the upper electrode 30 during plasma processing. For example, the power supply 70 may supply a negative DC voltage to the upper electrode 30, or may periodically supply low-frequency power. DC voltage or low-frequency power can be supplied in the form of pulse waves or in the form of continuous waves. In this embodiment, the positive ions present in the plasma processing space 10s are fed into the upper electrode 30 and collide therewith. Thereby, secondary electrons are released from the upper electrode 30 . The released secondary electrons modify the mask film MK to improve the etching resistance of the mask film MK. Also, secondary electrons contribute to increase the plasma density. In addition, since the charged state of the substrate W is neutralized by the irradiation of the secondary electrons, it is possible to improve the linearity of the ions into the concave portion formed by etching. Furthermore, when the upper electrode 30 contains a silicon-containing material, silicon is released together with secondary electrons by collision of positive ions. The released silicon is bonded with oxygen in the plasma to form a silicon oxide compound, which is deposited on the mask to function as a protective film. As described above, by supplying a DC voltage or low-frequency power to the upper electrode 30 , not only the selectivity is improved, but also the effect of suppressing abnormal shape of the recess formed by etching and improving the etching rate can be obtained.

When plasma processing is performed in the substrate processing apparatus 1, gas is supplied from the gas supply part to 10 s of internal spaces. Moreover, a high-frequency electric field is generated between the upper electrode 30 and the lower electrode 18 by supplying high-frequency power HF and/or an electric bias voltage. The generated high-frequency electric field generates plasma from the gas in the inner space 10s.

The substrate processing apparatus 1 may further include a control unit 80 . The control unit 80 may be a computer including a processor, a storage unit such as a memory, an input device, a display device, an input/output interface for signals, and the like. The control unit 80 controls each unit of the substrate processing apparatus 1 . In the control unit 80 , the operator can use the input device to perform command input operations and the like to manage the substrate processing apparatus 1 . In addition, in the control unit 80, the operation status of the substrate processing apparatus 1 can be visualized and displayed by the display device. Furthermore, the control program and process recipe data are stored in the memory. The control program is executed by the processor to execute various processes in the substrate processing apparatus 1 . The processor executes the control program, and controls each part of the substrate processing device 1 according to the process recipe data. In an exemplary embodiment, part or all of the control unit 80 may be provided as a part of the configuration of an external device of the substrate processing device 1 .

＜Substrate processing system PS structure＞ FIG. 3 is a diagram schematically showing a substrate processing system PS according to an exemplary embodiment. The processing method can also be performed using the substrate processing system PS.

The substrate processing system PS includes substrate processing chambers PM1 to PM6 (hereinafter, also collectively referred to as "substrate processing module PM"), transfer module TM, load lock modules LLM1 and LLM2 (hereinafter, also collectively referred to as "load lock module LLM"). ”), the carrier module LM, and the load ports LP1 to LP3 (hereinafter, also collectively referred to as “load ports LP”). The control unit CT controls each component of the substrate processing system PS, and executes a specific process on the substrate W.

The substrate processing module PM performs etching, trimming, film forming, annealing, doping, lithography, cleaning, ashing, etc. on the substrate W inside. A part of the substrate processing module PM may be a measurement module, which may also measure the film thickness of the film formed on the substrate W or the size of the pattern formed on the substrate W. The substrate processing apparatus 1 shown in FIG. 1 is an example of the substrate processing module PM.

The transfer module TM has a transfer device for transferring the substrate W, and transfers the substrate W between the substrate processing modules PM or between the substrate processing module PM and the load lock module LLM. The substrate processing module PM and the load lock module LLM are arranged adjacent to the transfer module TM. The transfer module TM, the substrate processing module PM, and the load lock module LLM are spatially separated or connected by openable and closable gate valves.

The load lock modules LLM1 and LLM2 are disposed between the transfer module TM and the carrier module LM. The load lock module LLM can switch its internal pressure to atmospheric pressure or vacuum. The load lock module LLM transfers the substrate W from the atmospheric pressure carrier module LM to the vacuum transfer module TM, and from the vacuum transfer module TM to the atmospheric pressure carrier module LM.

The carrier module LM has a transfer device for transferring the substrate W, and transfers the substrate W between the load lock module LLM and the load port LP. The inside of the load port LP can be loaded with, for example, a FOUP (Front Opening Unified Pod, Front Opening Unified Pod) capable of accommodating 25 substrates W or an empty FOUP. The carrier module LM takes out the substrate W from the FOUP in the load port LP, and transfers it to the load lock module LLM. Moreover, the carrier module LM takes out the substrate W from the load lock module LLM, and transfers it to the FOUP in the load port LP.

The control unit CT controls each component of the substrate processing system PS, and executes a specific process on the substrate W. The control unit CT stores a recipe that sets the steps of the manufacturing procedure, the conditions of the manufacturing procedure, and the transfer conditions, etc., and controls each component of the substrate processing system PS according to the recipe to perform specific processing on the substrate W. The control unit CT may also have a part or all of the functions of the control unit 80 of the substrate processing apparatus 1 shown in FIG. 1 .

<Example of Substrate W> FIG. 4 is a diagram showing an example of the cross-sectional structure of the substrate W. As shown in FIG. The substrate W is an example of a substrate to which this processing method can be applied. The substrate W has a dielectric film DF. The substrate W may have a base film UF and a mask film MK. As shown in FIG. 4 , the substrate W can be formed by sequentially laminating the base film UF, the dielectric film DF and the mask film MK.

The base film UF can be, for example, a silicon wafer or an organic film, a dielectric film, a metal film, a semiconductor film, etc. formed on the silicon wafer. The base film UF may be formed by laminating a plurality of films.

The dielectric film DF may be a silicon-containing film. The silicon-containing film is, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film (SiON film), and a Si-ARC film. The dielectric film DF may include a polysilicon film. The dielectric film DF may be formed by laminating a plurality of films. For example, the dielectric film DF may be formed by alternately laminating silicon oxide films and polysilicon films. In one example, the dielectric film DF is a laminated film in which silicon oxide films and silicon nitride films are alternately laminated.

The base film UF and/or the dielectric film DF can be formed by a CVD (Chemical Vapor Deposition, chemical vapor deposition) method, a spin coating method, or the like. The base film UF and/or the dielectric film DF may be a flat film, or may have unevenness.

A mask film MK is formed on the dielectric film DF. The mask film MK defines at least one opening OP on the dielectric film DF. The opening OP is a space on the dielectric film DF, and is surrounded by the sidewall S1 of the mask film MK. That is, in FIG. 4 , the dielectric film DF has a region covered by the mask film MK and a region exposed at the bottom of the opening OP.

The opening OP may have any shape when the substrate W is viewed from above (when the substrate W is viewed from the top to the bottom in FIG. 4 ). The shape can be, for example, a hole shape or a line shape, a combination of a hole shape and a line shape. The mask film MK may also have a plurality of sidewalls S1, and a plurality of openings OP are defined by the plurality of sidewalls S1. The plurality of openings OP may respectively have a line shape and be arranged at regular intervals to form a line-and-space pattern. Also, the plurality of openings OP may each have a hole shape and form an array pattern.

The mask film MK is, for example, an organic film or a metal-containing film. The organic film can be, for example, a spin-on carbon film (SOC), an amorphous carbon film, or a photoresist film. Metal-containing films may include, for example, tungsten, tungsten carbide, and titanium nitride. The mask film MK can be formed by a CVD method, a spin coating method, or the like. The opening OP can be formed by etching the mask film MK. The mask film MK can also be formed by lithography.

In one example, the substrate W may have a laminated film obtained by laminating a silicon oxide film and a silicon nitride film as the dielectric film DF on the base film UF. Also, in one example, the substrate W may have a polysilicon film, silicon boride, or tungsten carbide as the mask film MK on the silicon nitride film. In addition, the mask film MK may be a multi-layer resist including polysilicon film, silicon boride or tungsten carbide. In one example, the multilayer resist has a mask including a hard mask on the polysilicon film. In one example, the hard mask has a silicon oxide film (TEOS (tetraethoxysilane, tetraethoxysilane) film). The silicon nitride film included in the laminated film can be etched using the hard mask as a mask, and the silicon oxide film included in the laminated film can be etched using the polysilicon film as a mask.

<An example of this processing method> Fig. 5 is a flowchart showing the processing method. This processing method includes a step of preparing a substrate (step ST1 ), and an etching step (step ST2 ). Hereinafter, a case where the control unit 80 shown in FIG. 1 controls each part of the substrate processing apparatus 1 to execute the present processing method on the substrate W shown in FIG. 4 will be described as an example.

(Step ST1: Preparation of substrate) In step ST1 , the substrate W is prepared in the inner space 10 s of the chamber 10 . In the inner space 10 s , the substrate W is placed on the upper surface of the substrate holder 14 and held by the electrostatic chuck 20 . At least a part of the processes for forming the components of the substrate W can be performed in the internal space 10s. In addition, after all or part of the components of the substrate W are formed in a device or chamber outside the substrate processing device 1 , the substrate W may be carried into the internal space 10 s and placed on the upper surface of the substrate holder 14 .

(Step ST2: etching process) In step ST2, etching of the dielectric film DF of the substrate W is performed. Step ST2 includes a step of supplying a process gas (step ST21 ) and a step of generating plasma (step ST22 ). The dielectric film DF is etched by the active species (ions, radicals) of the plasma generated from the process gas.

In step ST21, the processing gas is supplied from the gas supply unit into the internal space 10s. The processing gas includes a gas containing fluorine-containing gas and C _x H _y F _z (a gas different from the above-mentioned fluorine-containing gas, x is an integer greater than 2, and y and z are integers greater than 1) gas (hereinafter, the gas Reactive gas known as "C _x H _y F _z gas"). In this embodiment, noble gases such as Ar are not contained in the reaction gas unless otherwise stated.

The fluorine-containing gas may be a gas capable of generating hydrogen fluoride (HF) species within the chamber 10 during plasma processing. The HF species includes at least any one of hydrogen fluoride gas, radicals, and ions. In one example, the fluorine-containing gas may be HF gas or hydrofluorocarbon gas. Also, the fluorine-containing gas may be a mixed gas containing a hydrogen source and a fluorine source. The hydrogen source can be, for example, H ₂ , NH ₃ , H ₂ O, H ₂ O ₂ or hydrocarbons (CH ₄ , C ₃ H ₆ , etc.). The fluorine source can be NF ₃ , SF ₆ , WF ₆ , XeF ₂ , fluorocarbons or hydrofluorocarbons. Hereinafter, these fluorine-containing gases are also referred to as "HF-based gases". Plasma generated from a process gas containing HF-based gas contains a large amount of HF species (etchant). The flow rate of HF gas can be more than that of C _x H _y F _z gas. The HF-based gas may also be the main etchant gas. The flow ratio of the HF-based gas in the total flow rate of the reaction gas may be the largest, for example, it may be 70% by volume or more relative to the total flow rate of the reaction gas. In addition, the total flow rate of the HF-based gas to the reaction gas may be 96% by volume or less.

C _{x Hy} F _z gas, for example, C _{x Hy} F _z (x is an integer of 2 or more, and y and z are integers of 1 or more) gas can be used. As the C _x H _y F _z (x is an integer of 2 or more, y and z are an integer of 1 or more) gas, specifically, a gas selected from C ₂ HF ₅ , C ₂ H ₂ F ₄ gas, C ₂ H ₃ F ₃ gas, C ₂ H ₄ F ₂ gas, C ₃ HF ₇ gas, C ₃ H ₂ F ₂ gas, C ₃ H ₂ F ₄ gas, C ₃ H ₂ F ₆ gas, C ₃ H ₃ F ₅ gas, C ₄ H ₂ F ₆ gas, C ₄ H ₅ F ₅ gas, C ₄ H ₂ F ₈ gas, C ₅ H ₂ F ₆ gas, C ₅ H ₂ F ₁₀ gas and C ₅ H ₃ F ₇ gas At least one of the group formed. In one example, as the C _x H _y F _z gas, a gas selected from C ₃ H ₂ F ₄ gas, C ₃ H ₂ F ₆ gas, C ₄ H ₂ F ₆ gas and C ₄ H ₂ F ₈ gas is used. At least 1 species in the group. In another example, as C _x H _y F _z gas, use is selected from C ₃ H ₂ F ₄ gas, C ₃ H ₂ F ₆ gas, C ₄ H ₂ F ₆ gas, C ₄ H ₂ F ₈ gas and C At least one of the group consisting of ₅ H ₂ F ₆ gases. As the C _x H _y F _z gas, for example, when using C ₄ H ₂ F ₆ gas, C ₄ H ₂ F ₆ may be linear or cyclic.

The plasma generated from the process gas comprising the _{CxHyFz gas comprises CxHyFz species dissociated} from the _{CxHyFz gas .} A large _{number of C x H y F z free radicals (} for example, C ₂ H ₂ F free radicals, C ₂ H ₂ F ₂ free radicals, C 2 H 2 F free radicals, C ₃ HF ₃ free radicals, hereinafter referred to as "C _x H _y F _z free radicals"). The C _x H _y F _z free radicals form a protective film on the surface of the mask film MK to protect the surface. This protective film can suppress the etching of the mask film MK when the dielectric film DF is etched. Therefore, C _x H _y F _z free radicals can improve the selectivity ratio of the dielectric film DF relative to the mask film MK in the etching of the dielectric film DF (dividing the etching rate of the dielectric film DF by the mask MK The value obtained from the etching rate).

Also, the plasma generated from the process gas _{containing CxHyFz gas contains a large number of HF species dissociated from the CxHyFz gas and / or} further _{dissociated from CxHyFz radicals .} The HF species includes at least any one of hydrogen fluoride gas, radicals, and ions. The HF species function as an etchant for the dielectric film DF. By including a large amount of HF species in the plasma, the etching rate of the dielectric film DF can be increased.

The C _x H _y F _z gas may have one or more CF ₃ groups. When the C _{x Hy} F _z gas has a CF ₃ group, for example, when the CH group and the CF ₃ group form a single bond, it is easy to dissociate into HF due to its molecular structure, so that HF can be used in the plasma Species increase.

Furthermore, the processing gas may include C _x F _z (x is an integer greater than 2, z is an integer greater than 1) gas instead of part or all of the above-mentioned C _x H _y F _z gas. Specifically, at least one selected from the group consisting of C ₂ F ₂ , C ₂ F ₄ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ and C ₅ F ₈ can also be used. Thereby, the amount of hydrogen in the plasma can be suppressed, for example, the deterioration of morphology or the increase of moisture in the chamber 10 caused by excessive hydrogen can be suppressed. Here, the shape refers to the characteristics related to the shape of the mask, such as the surface state of the mask film MK, the roundness of the opening OP, and the like.

The flow rate of the C _x H _y F _z gas is 20% by volume or less relative to the total flow rate of the reaction gas. The flow _{rate of the CxHyFz gas may} be, for example, 15 vol % or less, 10 vol % or less, or 5 vol % or less with respect to the total flow rate of the reaction gas.

The reactive gas may contain a halogen-containing gas. The gas containing halogen can adjust the shape of the mask film MK or the dielectric film DF during etching. The halogen-containing gas may be a chlorine-containing gas, a bromine-containing gas, and/or an iodine-containing gas. As chlorine-containing gas, Cl ₂ , SiCl ₂ , SiCl ₄ , CCl ₄ , SiH ₂ Cl ₂ , Si ₂ Cl ₆ , CHCl ₃ , SO ₂ Cl ₂ , BCl ₃ , PCl ₃ , PCl ₅ , POCl ₃ and other gases can be used. . As the bromine-containing gas, gases such as Br ₂ , HBr, CBr ₂ F ₂ , C ₂ F ₅ Br, PBr ₃ , PBr ₅ , POBr ₃ , and BBr ₃ can be used. As the iodine-containing gas, gases such as HI, CF ₃ I, C ₂ F ₅ I, C ₃ F ₇ I, IF ₅ , IF ₇ , I ₂ , and PI ₃ can be used. In one example, at least one selected from the group consisting of Cl ₂ gas, Br ₂ gas, HBr gas, CF ₃ I gas, IF ₇ gas, and C ₂ F ₅ Br is used as the halogen-containing gas. In another example, Cl ₂ gas and HBr gas are used as the halogen-containing gas.

The reaction gas may also contain nitrogen-containing gas. The nitrogen-containing gas can suppress clogging of the opening OP of the mask film MK during etching. The nitrogen-containing gas may be, for example, at least one gas selected from the group consisting of NF ₃ gas, N ₂ gas and NH ₃ gas.

The reactive gas may contain an oxygen-containing gas. Similar to the nitrogen-containing gas, the oxygen-containing gas suppresses clogging of the mask film MK during etching. As the oxygen-containing gas, for example, at least one gas selected from the group consisting of O ₂ , CO, CO ₂ , H ₂ O and H ₂ O ₂ can be used. In one example, the reaction gas contains an oxygen-containing gas other than H ₂ O, that is, at least one gas selected from the group consisting of O ₂ , CO, CO ₂ and H ₂ O ₂ . Oxygen-containing gas causes less damage to the mask film MK and suppresses deterioration of the shape.

FIG. 6 is a diagram showing an example of the shape of the mask film MK after etching. FIG. 6 shows an example of the shape (planar view) of the mask film MK when a sample substrate having the same structure as the substrate W is etched in the substrate processing apparatus 1 . In FIG. 6, "No." represents the sample number of the sample substrate after etching. "Processing gas" refers to the processing gas used in etching, and "A" represents the processing gas including HF gas, C ₄ H ₂ F ₆ gas, O ₂ gas, NF ₃ gas, HBr gas and Cl ₂ gas (hereinafter referred to as "Process Gas A"). The processing gas A contains HF gas at 80% by volume or more relative to the total flow rate of the reaction gas, and contains O ₂ gas at 4-5% by volume relative to the total flow rate of the reaction gas. "B" in "processing gas" means the same processing gas as processing gas A except that NF ₃ gas is not included and the flow rate of O ₂ gas is increased accordingly (hereinafter referred to as "processing gas B"). The processing gas B contains O ₂ gas in an amount of 6-7 volume % relative to the total flow rate of the reaction gas. “Yes” in “upper electrode application” indicates that a negative DC voltage is supplied to the upper electrode 30 of the substrate processing apparatus 1 during etching, and “None” indicates that a negative DC voltage is not supplied to the upper electrode 30 . From the "mask shape" in Fig. 6, it can be seen that in the case of "yes" and "no" of "upper electrode application", when the processing gas A containing NF ₃ is used (sample 1 and sample 3), The roundness of the opening OP will be deteriorated and a level difference will be generated on the surface of the mask film MK. On the other hand, it can be seen that when using the processing gas B (sample 2 and sample 4) that does not contain NF ₃ gas and increases the flow rate of O ₂ gas, the roundness of the opening OP is higher, and there is no gap between the opening OP and the mask film. The surface of MK has a step difference, and compared with the case of using process gas A (sample 1 and sample 3), the shape of the mask film MK is improved.

The reaction gas may contain a phosphorus-containing gas. As the phosphorus-containing gas, for example, a gas selected from PF ₃ , PF ₅ , POF ₃ , HPF ₆ , PCl ₃ , PCl ₅ , POCl ₃ , PBr ₃ , PBr ₅ , POBr ₃ , PI ₃ , P ₄ O ₁₀ , P At least one gas from the group consisting of ₄ O ₈ , P ₄ O ₆ , PH ₃ , Ca ₃ P ₂ , H ₃ PO ₄ and Na ₃ PO ₄ . Among them, phosphorus halide-containing gases such as PF ₃ , PF ₅ , and PCl ₃ can be used. For example, phosphorus fluoride-containing gases such as PF ₃ and PF ₅ can also be used.

In addition, the processing gas may also include boron-containing gases such as BF ₃ , BCl ₃ , BBr ₃ , and B ₂ H ₆ . In addition, the processing gas may contain sulfur-containing gases such as SF ₆ and COS.

The processing gas may contain an inert gas (noble gas such as Ar) in addition to the above-mentioned reaction gas.

The pressure of the process gas supplied into the inner space 10s is adjusted by controlling the pressure regulating valve of the exhaust device 50 connected to the chamber body 12 . The pressure of the processing gas can be above 5 mTorr (0.7 Pa) and below 100 mTorr (13.3 Pa), above 10 mTorr (1.3 Pa) below 60 mTorr (8.0 Pa), or above 20 mTorr (2.7 Pa) and below 40 mTorr (5.3 Pa) the following.

Next, in step ST22, high-frequency power and/or electrical bias are supplied from the plasma generation unit (high-frequency power supply 62 and/or bias power supply 64). Thereby, a high-frequency electric field is generated between the upper electrode 30 and the substrate holder 14, and plasma is generated from the processing gas in the internal space 10s. Active species such as ions and free radicals in the generated plasma are attracted by the substrate W to etch the substrate W.

In step ST22, the temperature of the substrate holder 14 is set to 0° C. or lower. The set temperature of the substrate holder 14 may be, for example, below 0°C, or below -10°C, below -20°C, below -30°C, below -40°C, below -60°C, or below -70°C. The temperature of the substrate holder 14 can be adjusted by the heat exchange medium supplied from the cooler unit.

FIG. 7 is a graph showing an example of temperature dependence of etching. FIG. 7 shows experimental results obtained by etching a silicon oxide film by using the plasma processing apparatus 1 to generate plasma from a processing gas which is a mixed gas of hydrogen fluoride gas and argon gas. In this experiment, the silicon oxide film was etched while changing the temperature of the substrate holder 14, and the concentration of hydrogen fluoride (HF) in the gas phase during etching of the silicon oxide film was measured using a quadrupole mass analyzer. The amount and the amount of SiF ₃ . The horizontal axis of FIG. 7 represents the temperature T (° C.) of the substrate holder 14 , and the vertical axis represents the amounts of hydrogen fluoride (HF) and SiF ₃ (intensities normalized to helium).

As shown in FIG. 7 , when the temperature of the substrate holder 14 is about -60° C. or lower, the amount of hydrogen fluoride (HF) as an etchant decreases, and SiF ₃ , the reaction product generated by etching the silicon oxide film, is reduced. The amount increased. That is, in this experiment, when the temperature of the substrate holder 14 was about −60° C. or lower, the amount of etchant used for etching the silicon oxide film increased.

Therefore, according to this experiment, it can be seen that the lower the temperature of the substrate holder 14, the more the etching of the silicon oxide film is promoted, and thus the selectivity ratio of the dielectric film DF to the mask film MK can be improved. Furthermore, the temperature at which the amount of etchant is increased varies depending on the relationship with the flow ratio of hydrogen fluoride gas in the reaction gas or the processing conditions such as added gas. Therefore, the relationship between the temperature of the substrate holder 14 and the amount of hydrogen fluoride and the amount of SiF ₃ can also be investigated under specific conditions, and the temperature of the substrate holder 14 can be set based on the results.

FIG. 8 is a diagram showing an example of a cross-sectional structure of the substrate W in step ST22. When step ST22 is performed, the mask film MK functions as a mask, and the portion of the dielectric film DF corresponding to the opening OP of the mask film MK is etched in the depth direction (direction from top to bottom in FIG. 8 ), and The concave 01 portion RC is formed. The recess RC is a space surrounded by the side wall S1 of the mask film MK and the side wall S2 of the dielectric film DF. The aspect ratio of the recess RC formed in step ST22 may be 20 or more, or 30 or more, 40 or more, 50 or more, or 100 or more.

In this processing method, the reaction gas includes C _x H _y F _z gas. C _x H _y F _z gas generates C _x H _y F _z free radicals with high density in the plasma. C _x H _y F _z is free radicals adsorbed on the surface of the mask film MK (the upper surface T1 and the sidewall S1 ) or the sidewall S2 of the dielectric film DF to form the protection film PF. Furthermore, the protective film PF may become thinner toward the depth direction (direction from top to bottom in FIG. 8 ). The protective film PF inhibits the surface of the mask film MK from being etched away when step ST22 is performed (ie, the etching rate of the mask film MK increases). Thereby, the selectivity ratio of the dielectric film DF with respect to the mask film MK improves.

The protective film PF can suppress etching in the lateral direction (left and right direction in FIG. 8 ) of the dielectric film DF. When the flow rate of the C _x H _y F _z gas relative to the total flow rate of the reaction gas is 20% by volume or less, it can further suppress excessive deposition of carbon on the sidewall S1 of the mask film MK and/or the dielectric film DF to cause masking. The opening OP of the mask MK is blocked. When the reaction gas contains oxygen-containing gas, excessive deposition of carbon on the sidewall S1 of the mask film MK and/or the dielectric film DF can be further prevented from clogging the opening OP of the mask film MK. By at least one of the above factors, the shape and/or size of the recess RC formed in the dielectric film DF can be properly maintained.

C _x H _y F _z gas generates a large number of HF species in the plasma. Therefore, when step ST22 is performed, the HF-based species (etchant) can be sufficiently supplied even to the bottom BT of the recess RC formed in the dielectric film DF. In addition, when performing step ST22, the temperature of the substrate holder 14 is controlled to a low temperature below 0°C. By suppressing the temperature rise of the substrate W, the adsorption of HF species (etchant) at the bottom BT of recess RC can be promoted (the adsorption coefficient of HF species is further increased at low temperature). With at least one of the above factors, the etching rate of the dielectric film DF can be increased.

Furthermore, in step ST22 , when plasma is generated in the internal space 10 s, a pulse wave of an electrical bias may be periodically applied to the substrate holder 14 from the bias power supply 64 . Etching and formation of the protective film PF can be alternately performed by periodically applying a pulse wave of an electric bias.

Also, when step ST2 is _executed , the flow rate of the _CxHyFz gas supplied to the internal space 10s _can be changed. For example, after the first etching _is performed _using the reactive gas containing the first partial pressure of the _CxHyFz gas, the second etching may be performed _using the _reactive gas containing the second partial pressure of the _CxHyFz gas. Thereby, for example, when the dielectric film DF is a laminated film of different materials, the laminated film can be _properly etched by _{controlling the flow rate of the CxHyFz gas} in combination with the material of the film to be etched.

In addition, when step ST2 is _{performed, the flow rate of the CxHyFz gas} supplied to the inner space _10s may be different between the central part and the peripheral part of the substrate W when the substrate W is viewed from above. Thereby, even when the size of the opening OP surrounded by the side wall S1 of the mask film MK is different between the central part and the peripheral part of the substrate W, it is possible to control the _{distribution of the flow rate of the CxHyFz gas .} Correct the deviation of this dimension.

In addition, when performing step ST2, the pressure in the chamber 10 (inner space 10s) or the electrical bias supplied from the bias power supply 64 to the substrate holder 14 can be changed. For example, step ST2 may include: a first step of setting the inside of the chamber 10 to a first pressure, supplying a first electrical bias to the substrate holder 14 to etch the dielectric film DF; and a second step of etching the dielectric film DF. The dielectric film DF is etched by setting the inside of the chamber 10 at the second pressure and supplying the second electrical bias to the substrate holder 14 . Step ST2 may alternately repeat the first process and the second process. The first pressure may be different from the second pressure, for example, may be greater than the second pressure. The first electrical bias can be different from the second electrical bias, for example, the absolute value of the first electrical bias can be greater than the absolute value of the second electrical bias. By appropriately adjusting the first pressure, the second pressure, the first electrical bias, and the second electrical bias, for example, in the first process, the dielectric film DF can be treated before or immediately before the concave portion RC reaches the base film UF. In the anisotropic etching, in the second step, isotropic etching is performed so that the bottom of the recess RC expands in the lateral direction.

Hereinafter, various experiments conducted to evaluate this treatment method will be described. The present invention is not limited by the following experiments.

(Experiment 1) FIG. 9 is a graph showing the measurement results of Experiment 1. FIG. In Experiment 1, the amount of HF species produced in various reaction gases was measured. In Experiment 1, any one of C ₄ H ₂ F ₆ gas, C ₄ F ₈ gas, C ₄ F ₆ gas, and CH ₂ F ₂ gas and Ar gas were supplied to the inner space 10s of the substrate processing apparatus 1 as reaction gases. The plasma was generated for 10 minutes, and the HF intensity before and after the plasma generation was measured by a quadrupole mass analyzer. The temperature of the substrate holder 14 was set at -40°C. The vertical axis of FIG. 9 represents the difference between the HF intensity before plasma generation and the HF intensity after plasma generation. The larger the value on the vertical axis, the larger the amount of HF species generated in the plasma.

As shown in Figure 9, the C ₄ H ₂ F ₆ gas of one embodiment of the reaction gas of this treatment method is self-evident compared with the C ₄ F ₈ gas and C ₄ F ₆ gas without hydrogen, even if compared with Compared with CH ₂ F ₂ gas containing hydrogen, the generation amount of HF species in the plasma is also larger.

(Experiment 2) FIGS. 10 and 11 are diagrams showing the measurement results of Experiment 2. FIG. In experiment 2, the etching rate and selectivity ratio under various processing gases were measured. In Experiment 2, a sample substrate having the same structure as the substrate W was prepared on the substrate holder 14 . The sample substrate has silicon oxide as the dielectric film DF and an organic film as the mask film MK on the silicon film. A process gas is supplied to the inner space 10s of the substrate processing apparatus 1 to generate plasma to etch the dielectric film DF of the sample substrate. The temperature of the substrate holder 14 was set at -40°C. As shown in Figure 10 and Figure 11, when the reaction gas in the processing gas is any one of C ₄ F ₈ gas, CH ₂ F ₂ gas or C ₄ H ₂ F ₆ gas, the DF of the dielectric film is measured The etching rate (E/R [nm/min], FIG. 10) and the selectivity ratio of the dielectric film DF relative to the mask film MK (Sel., FIG. 11). The flow rate of C ₄ F ₈ gas is 5% by volume of the total flow rate of reaction gas. The flow rate of CH ₂ F ₂ gas is 15% by volume of the total flow rate of the reaction gas. The flow rate of C ₄ H ₂ F ₆ gas is 5% by volume of the total flow rate of reaction gas. The reaction gas contains 70 to 90% by volume of HF gas relative to the total flow rate of the reaction gas.

As shown in Figure 10 and Figure 11, one embodiment of the reaction gas of this processing method is a processing gas containing C ₄ H ₂ F ₆ gas and a processing gas containing C ₄ F ₈ gas or CH ₂ F ₂ gas as a reactive gas In comparison, the etch rate and selectivity are higher.

(Experiment 3) FIGS. 12 and 13 are diagrams showing the measurement results of Experiment 3. FIG. In Experiment 3, the etching rate and bow CD (Critical Dimension, critical dimension) were measured under various process gases when the aspect ratio of the recess RC was changed. In Experiment 3, a sample substrate having the same structure as in Experiment 2 was prepared on the substrate holder 14 . A process gas is supplied to the inner space 10s of the substrate processing apparatus 1 to generate plasma to etch the dielectric film DF of the sample substrate. The temperature of the substrate holder 14 was set at -40°C. Fig. 12 and Fig. 13 show the dielectric film DF relative to the mask when changing the aspect ratio (AR) of the recess RC for each case where the reaction gas in the processing gas contains C ₄ F ₈ gas or C ₄ H ₂ F ₆ gas. The relationship between the selectivity of the film MK (Sel., FIG. 12 ) and the maximum width of the recess RC of the dielectric film DF (bow CD: CD _m [nm], FIG. 13 ). Furthermore, the selectivity can be obtained by dividing the etching rate of the dielectric film DF by the etching rate of the mask film MK. 5% by volume of the total flow rate of C ₄ F ₈ gas or C ₄ H ₂ F ₆ gas system reaction gas. The reaction gas contains HF gas at 90% by volume or more with respect to the total flow rate of the reaction gas.

As shown in FIG. ₁₂ and FIG. ₁₃ , when the reaction gas containing _C4H2F6 gas which is an embodiment of the processing gas of this processing method is used, even if the aspect ratio of the concave part RC formed in the dielectric film DF becomes high, The selectivity was also maintained higher than when the reaction gas containing C ₄ F ₈ gas was used, and the increase in bow CD was suppressed.

(Experiment 4) FIG. 14 is a graph showing the measurement results of Experiment 4. FIG. In Experiment 4, the temporal change in the emission spectrum intensity (CO intensity) of CO generated when the chamber 10 of the substrate processing apparatus 1 was cleaned with oxygen was measured. In FIG. 14 , CH1 is a chamber after etching a sample substrate having the same structure as in Experiment 2 using a process gas containing 4 vol % of C ₄ H ₂ F ₆ gas relative to the total flow rate of the reaction gas. CH2 is a chamber after etching a sample substrate having the same structure as in Experiment 2 using a process gas containing 16% by volume of CH ₂ F ₂ gas relative to the total flow rate of the reaction gas. The CO intensity is measured by the reaction of the cleaning gas (oxygen) with the carbonaceous deposits in the chamber 10 and can be used as a guide for the progress of the cleaning in the chamber.

As shown in Figure 14, the CO intensity in CH1 peaked immediately after the cleaning started, then decreased sharply, and became zero 20-30 seconds after the cleaning started. The CO intensity in CH2 has a peak value lower than that of CH1, and the amount of decrease is moderate, and it does not become zero even after 200 seconds from the start of cleaning. That is, when using the processing gas containing C ₄ H ₂ F ₆ gas, which is an embodiment of the reaction gas of the processing method, compared with using the processing gas containing CH ₂ F ₂ gas, the length of the chamber after etching can be shortened. Cleaning time.

Moreover, the disclosed embodiment further includes the following aspects.

(Appendix 1) An etching gas composition comprising HF gas and a gas selected from C ₄ H ₂ F ₆ gas, C ₄ H ₂ F ₈ gas, C ₃ H ₂ F ₄ gas, and C ₃ H ₂ F ₆ gas. The reaction gas of at least one C _x H _y F _z gas in the group formed, and the flow rate of the above-mentioned HF gas is greater than the flow rate of the above-mentioned C _x H _y F _z gas.

( _{Additional Note 2) The etching gas composition according to Additional Note 1, wherein the flow rate of the above-mentioned CxHyFz gas relative} to the total flow rate of the above-mentioned reaction gas is 20% by volume or less.

(Note 3) The etching gas composition of Supplement 1 or 2, wherein the flow rate of the above-mentioned HF gas relative to the total flow rate of the above-mentioned reaction gas is 70% by volume or more.

(Note 4) The etching gas composition according to any one of Supplements 1 to 3, wherein the reaction gas further includes a halogen-containing gas.

(Note 5) The etching gas composition as in appendix 4, wherein the above-mentioned halogen-containing gas system is at least one selected from the group consisting of chlorine-containing gas, bromine-containing gas, and iodine-containing gas.

(Annex 6) The etching gas composition as in annex 4, wherein the above-mentioned halogen-containing gas system is selected from Cl ₂ , SiCl ₂ , SiCl ₄ , CCl ₄ , SiH ₂ Cl ₂ , Si ₂ Cl ₆ , CHCl ₃ , SO ₂ Cl ₂ , BCl ₃ , PCl ₃ , PCl ₅ , POCl ₃ , Br ₂ , HBr, CBr ₂ F ₂ , C ₂ F ₅ Br, PBr ₃ , PBr ₅ , POBr ₃ , BBr ₃ , HI, CF ₃ I, C ₂ At least one species selected from the group consisting of F ₅ I, C ₃ F ₇ I, IF ₅ , IF ₇ , I ₂ and PI ₃ .

(Note 7) The etching gas composition according to any one of Supplements 1 to 5, wherein the reaction gas includes a phosphorus-containing gas.

(Note 8) The etching gas composition according to any one of Supplements 1 to 7, wherein the reaction gas further includes an oxygen-containing gas.

(Note 9) The etching gas composition according to any one of Supplements 1 to 8, wherein the reaction gas further includes at least one selected from the group consisting of boron-containing gas and sulfur-containing gas.

Various changes can be made in this processing method without departing from the scope and spirit of the present invention. For example, this processing method can be executed using a substrate processing apparatus using any plasma source such as inductively coupled plasma or microwave plasma, in addition to the capacitively coupled substrate processing apparatus 1 .

1: Substrate processing device 10: chamber 10s: Internal space 12: Chamber body 12e: Exhaust port 12g: gate valve 12p: access 13: Support Department 14: Substrate supporter 16: electrode plate 18: Lower electrode 18f: flow path 20: Electrostatic chuck 20p: DC power supply 20s: switch 22a: Piping 22b: Piping 24: Gas supply pipeline 25: Edge Ring 30: Upper electrode 32: Component 34: top plate 34a: gas ejection hole 36: Support body 36a: Gas diffusion chamber 36b: Multiple stomata 36c: gas inlet 38: Gas supply pipe 40: Gas source group 41: Flow controller group 42: valve group 46: shield 48: Baffle 50: exhaust device 52: exhaust pipe 62: High frequency power supply 64: Bias power supply 66: Matcher 68: Matcher 70: Power 80: Control Department BT: bottom CT: Control Department DF: Dielectric film LLM1: Load Lockout Module LLM2: Load Lockout Module LM: Carrier Module LP1: load port LP2: Load Port LP3: load port MK: masking film OP: opening PF: protective film PM1～PM6: Substrate processing chamber PS: substrate processing system RC: Concave S1: side wall S2: side wall T1: upper surface TM: Transport Module UF: basement membrane W: Substrate

FIG. 1 is a diagram schematically showing a substrate processing apparatus 1 . Fig. 2 is a timing chart showing an example of high-frequency power HF and electric bias. FIG. 3 is a diagram schematically showing the substrate processing system PS. FIG. 4 is a diagram showing an example of the cross-sectional structure of the substrate W. As shown in FIG. Fig. 5 is a flowchart showing the processing method. FIG. 6 is a diagram showing an example of the shape of the mask film MK after etching. FIG. 7 is a graph showing an example of temperature dependence of etching. FIG. 8 is a diagram showing an example of a cross-sectional structure of the substrate W in step ST22. FIG. 9 is a graph showing the measurement results of Experiment 1. FIG. FIG. 10 is a graph showing the measurement results of Experiment 2. FIG. FIG. 11 is a graph showing the measurement results of Experiment 2. FIG. FIG. 12 is a graph showing the measurement results of Experiment 3. FIG. FIG. 13 is a graph showing the measurement results of Experiment 3. FIG. FIG. 14 is a graph showing the measurement results of Experiment 4. FIG.

Claims (28)

A substrate processing method, which includes the following steps: preparing a substrate with a dielectric film on a substrate holder in a chamber; and self-contained HF gas and selected from C ₄ H ₂ F ₆ gas, C ₄ H ₂ F ₈ gas, The reaction gas of at least one C _x H _y F _z gas in the group consisting of C ₃ H ₂ F ₄ gas and C ₃ H ₂ F ₆ gas generates plasma to etch the above dielectric film; and during the above etching In the process, the temperature of the substrate holder is set below 0° C., and the flow rate of the HF gas is higher than the flow rate of the C _x H _y F _z gas. The substrate processing method according to claim 1, wherein the flow rate of the C _x H _y F _z gas relative to the total flow rate of the reaction gas is 20% by volume or less. The substrate processing method according to claim 1 or 2, wherein the flow rate of the HF gas relative to the total flow rate of the reaction gas is 70% by volume or more. The substrate processing method according to any one of claims 1 to 3, wherein the reaction gas further includes a halogen-containing gas. The substrate processing method according to claim 4, wherein the above-mentioned halogen-containing gas system is at least one selected from the group consisting of chlorine-containing gas, bromine-containing gas, and iodine-containing gas. Such as the substrate processing method of claim 4, wherein the gas system containing halogen is selected from Cl ₂ , SiCl ₂ , SiCl ₄ , CCl ₄ , SiH ₂ Cl ₂ , Si ₂ Cl ₆ , CHCl ₃ , SO ₂ Cl ₂ , BCl ₃ , PCl ₃ , PCl ₅ , POCl ₃ , Br ₂ , HBr, CBr ₂ F ₂ , C ₂ F ₅ Br, PBr ₃ , PBr ₅ , POBr ₃ , BBr ₃ , HI, CF ₃ I, C ₂ F ₅ I, At least one gas from the group consisting of C ₃ F ₇ I, IF ₅ , IF ₇ , I ₂ and PI ₃ . The substrate processing method according to any one of claims 1 to 6, wherein the reaction gas includes a phosphorus-containing gas. The substrate processing method according to any one of claims 1 to 7, wherein the reaction gas includes an oxygen-containing gas. The substrate processing method according to any one of claims 1 to 8, wherein the reaction gas further includes at least one selected from the group consisting of boron-containing gas and sulfur-containing gas. The substrate processing method according to any one of claims 1 to 9, wherein the plasma is generated from a processing gas containing the reactive gas and the inert gas. The substrate processing method according to any one of claims 1 to 10, wherein the dielectric film is a silicon-containing film. The substrate processing method according to claim 11, wherein the silicon-containing film includes at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, and a polysilicon film. The substrate processing method according to any one of claims 1 to 12, wherein the substrate has a mask that defines at least one opening on the dielectric film and includes an organic film or a metal-containing film. The substrate processing method according to any one of claims 1 to 13, wherein the etching step includes a step of applying an electrical bias to the substrate holder, The period in which the electrical bias is applied to the substrate holder includes a first period and a second period alternating with the first period, and The electrical bias voltage in the first period is 0 or the first level, and the electrical bias voltage in the second period is a second level greater than the first level. The substrate processing method as claimed in claim 14, wherein The etching process includes a step of supplying high-frequency power for generating plasma to the substrate holder or the upper electrode facing the substrate holder, The period of supplying the above-mentioned high-frequency power includes a third period and a fourth period which alternates with the above-mentioned third period, The level of the above-mentioned high-frequency power during the above-mentioned third period is 0 or the third level, and the level of the above-mentioned high-frequency power during the above-mentioned fourth period is the fourth level that is higher than the above-mentioned third level, and The second period and the fourth period overlap at least in part. The substrate processing method according to claim 14 or 15, wherein the electrical bias voltage is a pulse voltage. The substrate processing method according to any one of claims 1 to 16, wherein the etching step includes a step of supplying a DC voltage or low-frequency power to an upper electrode facing the substrate holder. The substrate processing method according to any one of Claims 1 to 17, wherein the etching process includes: a first step of etching the dielectric film by supplying a first electrical bias to the substrate holder by setting the inside of the chamber to a first pressure; and a second step of etching the dielectric film by applying a second electrical bias to the substrate holder by setting the inside of the chamber to a second pressure; and The first pressure is different from the second pressure and/or the first electrical bias is different from the second electrical bias. The substrate processing method according to claim 18, wherein the first pressure is greater than the second pressure. The substrate processing method according to claim 18 or 19, wherein the absolute value of the magnitude of the first electrical bias is greater than the absolute value of the magnitude of the second electrical bias. The substrate processing method according to any one of claims 18 to 20, wherein the first step and the second step are alternately repeated. A _substrate processing method, which includes the following steps: _preparing a substrate with a silicon- _containing film including a silicon oxide film on a substrate holder in a chamber; Gases with different gases, x is an integer greater than 2, and y and z are integers greater than 1) react gas to generate plasma to etch the above-mentioned silicon-containing film; and in the above-mentioned etching process, the temperature setting of the above-mentioned substrate holder 0°C or lower, and the flow rate of the above-mentioned C _x H _y F _z gas relative to the total flow rate of the above-mentioned reaction gas is 20% by volume or lower. The substrate processing method according to claim 22, wherein the fluorine-containing gas system can generate HF species gas in the chamber. The substrate processing method according to claim 22 or 23, wherein the above-mentioned C _x H _y F _z gas has more than one CF ₃ group. The substrate processing method as claimed in claim 24, wherein the above-mentioned C _x H _y F _z gas is selected from C ₃ H ₂ F ₄ gas, C ₃ H ₂ F ₆ gas, C ₄ H ₂ F ₆ gas, C ₄ H ₂ F At least one of the group consisting of ₈ gases and C ₅ H ₂ F ₆ gases. The substrate processing method according to any one of claims 22 to 25, wherein the flow rate of the fluorine-containing gas is the largest among the reaction gases. A substrate processing method, which includes the following steps: preparing a substrate having a silicon-containing film including a silicon oxide film on a substrate holder in a chamber; generating plasma in the chamber; and using HF species contained in the plasma and C _x H _y F _z (x is an integer greater than 2, y and z are integers greater than 1) species etches the silicon-containing film; and the amount of the HF species in the plasma is the largest. A substrate processing apparatus comprising a chamber, a substrate holder provided in the chamber and configured to be capable of temperature adjustment, a plasma generating unit supplying power for generating plasma in the chamber, and a control unit, and the above-mentioned In order to etch the dielectric film of the substrate supported on the substrate holder, the control unit performs control such that, by the power supplied from the plasma generation unit, gas containing HF and gas selected from C ₄ H ₂ F ₆ gas, C ₄ H ₂ F ₈ gas, C ₃ H ₂ F ₄ gas and C ₃ H ₂ F ₆ gas, the reaction gas of at least one C _x H _y F _z gas is introduced into the above chamber To generate plasma, in the above-mentioned control, the temperature of the above-mentioned substrate holder is set below 0° C., and the flow rate of the above-mentioned HF gas is greater than the flow rate of the above-mentioned C _x H _y F _z gas.

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