TWI888550B - Substrate processing method and substrate processing device - Google Patents

Abstract

In an exemplary 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 holder in a chamber; and etching the dielectric film by generating plasma from a reaction gas including _{HF gas and at least one CxHyFz gas selected from the group consisting of C4H2F6 gas , C4H2F8 gas , C3H2F4 gas} , and _{C3H2F6 gas ;} and in the etching step, the temperature of the substrate holder is set to be below 0° _C , and the flow rate of _{the HF} gas is greater than the flow rate _of the _{CxHyFz gas} .

Description

Substrate processing method and substrate processing device

The exemplary implementation of the present invention relates to a substrate processing method and a substrate processing device.

For example, Patent Document 1 describes a technique for etching a silicon oxide film.

Prior art literature Patent Literature

Patent document 1: Japanese Patent Publication No. 2016-122774

The present invention provides a technology for improving the etching selectivity of dielectric films for mask etching.

In an exemplary embodiment of the present invention, a substrate processing method is provided, which includes the following steps: preparing a substrate having a dielectric film on a substrate holder in a chamber; and etching the dielectric film by generating plasma from _a reaction gas including _{HF gas and at least one CxHyFz gas selected from the group consisting of C4H2F6 gas , C4H2F8 gas , C3H2F4 gas and C3H2F6 gas ; and in the} etching step, the temperature of the substrate holder is set to be below 0°C, and the flow rate of _{the HF} gas is greater than the flow rate of the _{CxHyFz gas .}

According to an exemplary embodiment of the present invention, a technology for improving the etching selectivity of a dielectric film for mask etching can be provided.

1: Substrate processing equipment

10: Chamber

10s: Inner space

12: Chamber body

12e: Exhaust port

12g: Gate valve

12p: Passage

13: Support Department

14: Substrate support

16: Electrode plate

18:Lower electrode

18f:Flow path

20: Electrostatic suction cup

20p: DC power supply

20s: switch

22a:Piping

22b:Piping

24: Gas supply pipeline

25: Edge Ring

30: Upper electrode

32: Components

34: Top plate

34a: Gas ejection hole

36: Support body

36a: Gas diffusion chamber

36b: Multiple pores

36c: Gas inlet

38: Gas supply pipe

40: Gas source group

41: Traffic 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 supply

80: Control Department

BT:Bottom

CT: Control Department

DF: Dielectric film

LLM1: Loading Lock Module

LLM2: Loading Lock Module

LM: Carrier module

LP1: Loading port

LP2: Loading port

LP3: Loading port

MK:Mask film

OP: Open your mouth

PF: Protective film

PM1~PM6: Substrate processing room

PS: Substrate processing system

RC: concave part

S1: Side wall

S2: Side wall

T1: Upper surface

TM: Transport module

UF: Basement membrane

W: substrate

FIG1 is a diagram schematically showing a substrate processing device 1.

Figure 2 is a timing diagram showing an example of high frequency power HF and electrical bias.

FIG3 is a diagram schematically showing the substrate processing system PS.

FIG4 is a diagram showing an example of the cross-sectional structure of the substrate W.

Figure 5 is a flow chart showing the processing method.

FIG6 is a diagram showing an example of the shape of the mask film MK after etching.

Figure 7 is a diagram showing an example of the temperature dependence of etching.

FIG8 is a diagram showing an example of the cross-sectional structure of the substrate W in step ST22.

Figure 9 is a graph showing the measurement results of Experiment 1.

Figure 10 is a graph showing the measurement results of Experiment 2.

Figure 11 is a diagram showing the measurement results of Experiment 2.

Figure 12 is a graph showing the measurement results of Experiment 3.

Figure 13 is a diagram showing the measurement results of Experiment 3.

Figure 14 is a diagram showing the measurement results of Experiment 4.

The following describes various implementation methods of the present invention.

In an exemplary 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 holder in a chamber; and _generating plasma from _a reaction gas including _{HF gas and at least one CxHyFz gas selected from the group consisting of C4H2F6 gas , C4H2F8 gas , C3H2F4 gas ,} and _C3H2F6 gas _to etch the dielectric film; in the etching step, the temperature _of the substrate holder is set to be below 0°C, and the flow rate of the _HF gas is greater than the flow rate _of the _{CxHyFz gas} .

In an exemplary embodiment, the flow rate _{of the CxHyFz gas is} less than 20 volume % relative to the total flow rate of the reaction gas.

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

In one exemplary embodiment, the reaction gas further comprises a halogen-containing gas.

In an exemplary embodiment, the halogen-containing gas 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 halogen-containing gas is at least one gas selected from _the group consisting of _Cl2 , SiCl2, _{SiCl4 , CCl4} , _{SiH2Cl2 , Si2Cl6} , _CHCl3 , _{SO2Cl2 , BCl3} , _{PCl3 , PCl5} , _POCl3 , _Br2 , _HBr , _CBr2F2 , _C2F5Br , _PBr3 , _PBr5 , _POBr3 , _BBr3 , HI, _CF3I , _C2F5I , _C3F7I , _IF5 , _IF7 , _I2 , _{and PI3 .}

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

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

In one 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 polycrystalline silicon film.

In one exemplary embodiment, 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.

In an exemplary embodiment, the etching process includes the step of applying an electrical bias to the substrate support, and the period of applying the electrical bias to the substrate support includes a first period and a second period alternating with the first period, the electrical bias in the first period is 0 or a first level, and the electrical bias in the second period is a second level greater than the first level.

In an exemplary embodiment, the etching process includes supplying high-frequency power for generating plasma to a substrate support or an upper electrode opposite to the substrate support, the period of supplying high-frequency power includes a third period and a fourth period alternating with the third period, the level of the high-frequency power in the third period is 0 or the third level, the level of the high-frequency power in the fourth period is a fourth level greater than the third level, and the second period and the fourth period overlap at least partially.

In one exemplary embodiment, the electrical bias is a pulse voltage.

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

In an exemplary embodiment, the etching process includes: a first process, which is to set the chamber to a first pressure, supply a first electrical bias to the substrate holder to etch the dielectric film; and a second process, which is to set the chamber to a second pressure, supply a 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.

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

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; and _generating plasma from a reactive gas including a fluorine- _{containing gas and CxHyFz (} a gas different from the fluorine-containing gas, x is an integer greater than 2, and y and _{z are integers greater than 1) to etch the silicon-containing film; and in the etching step, the temperature of the substrate holder is set to be below 0°C, and the flow rate of the CxHyFz gas} is below 20 volume % relative to the total flow rate of the _reactive gas.

In an exemplary embodiment, the fluorine-containing gas is a gas that can generate HF species in the above-mentioned chamber.

In an exemplary embodiment, the _{CxHyFz gas} has more than one _{CF3 group} .

In an exemplary embodiment, the _{CxHyFz gas includes} at least _one selected from _{the group consisting of C3H2F4 gas} , _{C3H2F6 gas} , _{C4H2F6 gas , C4H2F8 gas , and C5H2F6 gas .}

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

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; generating plasma in the chamber; and etching the silicon-containing film using _HF species and _CxHyFz (x is an integer greater than 2, y and z are integers greater than 1) species contained in the plasma; and the amount of HF species in the plasma _is the largest.

In one exemplary embodiment, a substrate processing apparatus is provided. A substrate processing apparatus includes a chamber, a substrate holder disposed in the chamber and configured to adjust the temperature thereof, a plasma generating unit for supplying power for generating plasma in the chamber, and a control unit. The control unit performs control to etch a dielectric film of a substrate supported on the substrate holder, that is, by introducing _a reaction gas including HF gas and at least one _{CxHyFz gas selected from the group consisting of C4H2F6 gas , C4H2F8} gas, _{C3H2F4 gas} , _{and C3H2F6 gas} into _the chamber by the power supplied from _the plasma generating unit to generate plasma, and in the control, the temperature of the substrate holder is set to be 0° _C or _less , and the flow rate of the _HF gas is greater than the flow rate _of the _{CxHyFz gas} .

Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. Furthermore, the same symbols are used for the same or identical elements in each drawing, and repeated descriptions are omitted. Unless otherwise specified in advance, the positional relationships such as up, down, left, and right are 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 device 1>

FIG1 is a diagram schematically showing a substrate processing apparatus 1 of an exemplary embodiment. A substrate processing method of an exemplary embodiment (hereinafter referred to as "the present processing method") can be performed using the substrate processing apparatus 1.

The substrate processing device 1 shown in FIG. 1 has 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, for example, aluminum. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. The corrosion-resistant film can be formed of ceramics such as aluminum oxide and yttrium oxide.

A passage 12p is formed on the side wall of the chamber body 12. The substrate W is transported 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 12g. The gate 12g is provided along the side wall of the chamber body 12.

A support portion 13 is provided 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 support portion 13 extends upward from the bottom of the chamber body 12 in the internal space 10s. The support portion 13 supports a substrate holder 14. The substrate holder 14 is configured to support a substrate W in the internal space 10s.

The substrate holder 14 has a lower electrode 18 and an electrostatic suction cup 20. The substrate holder 14 may further 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 suction cup 20 is disposed on the lower electrode 18. The substrate W is placed on the upper surface of the electrostatic suction cup 20. The electrostatic suction cup 20 has a body and an electrode. The body of the electrostatic suction cup 20 has a substantially disc shape and is formed of a dielectric. The electrode of the electrostatic suction cup 20 is a film electrode and is disposed in the body of the electrostatic suction cup 20. The electrode of the electrostatic suction cup 20 is connected to a DC power source 20p via a switch 20s. If a voltage from the DC power source 20p is applied to the electrode of the electrostatic suction cup 20, an electrostatic attraction is generated between the electrostatic suction cup 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 arranged on the substrate holder 14. The edge ring 25 is a ring-shaped component. The edge ring 25 can be formed of silicon, silicon carbide or quartz. The substrate W is arranged on the electrostatic chuck 20 and in the area surrounded by the edge ring 25.

A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (e.g., refrigerant) is supplied to the flow path 18f from a cooling unit provided outside the chamber 10 via a pipe 22a. The heat exchange medium supplied to the flow path 18f is returned to the cooling unit via a 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 device 1. The gas supply line 24 supplies heat transfer gas (such as 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 device 1 further includes an upper electrode 30. The upper electrode 30 is disposed above the substrate support 14. The upper electrode 30 is supported on the upper part of the chamber body 12 via a component 32. The component 32 is formed of an insulating material. The upper electrode 30 and the component 32 seal 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 of the inner space 10s side, dividing and forming 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 that penetrate the top plate 34 along the 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. A gas diffusion chamber 36a is provided inside the support body 36. The support body 36 has a plurality of air holes 36b extending downward from the gas diffusion chamber 36a. The plurality of air holes 36b are respectively connected to the plurality of gas ejection holes 34a. A gas inlet 36c is formed in the support body 36. The gas inlet 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet 36c.

The gas supply pipe 38 is connected to a gas source group 40 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 section. The gas supply section may further include a gas source group 40. The gas source group 40 includes a plurality of gas sources. The plurality of gas sources include the source of the treatment gas used in the present treatment method. The flow controller group 41 includes a plurality of flow controllers. The plurality of flow controllers of 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. The plurality of gas sources of the gas source group 40 are connected to the gas supply pipe 38 via 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 device 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. The shield 46 prevents the reaction byproducts from adhering to the chamber body 12. The shield 46 is formed, for example, by forming a corrosion-resistant film on the surface of a base material formed of aluminum. The corrosion-resistant film can be formed of ceramics such as yttrium oxide.

A baffle 48 is provided between the support portion 13 and the side wall of the chamber body 12. The baffle 48 is formed, for example, by forming a corrosion-resistant film (a film of yttrium oxide, etc.) on the surface of a component formed of aluminum. A plurality of through holes are formed in the baffle 48. An exhaust port 12e is provided below the baffle 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 vacuum pump such as a pressure regulating valve and a turbomolecular pump.

The substrate processing device 1 has a high-frequency power supply 62 and a bias power supply 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 in the range of 27 MHz to 100 MHz. The high-frequency power supply 62 is connected to the lower electrode 18 via a matcher 66 and an electrode plate 16. The matcher 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 can also be connected to the upper electrode 30 via the matcher 66. The high-frequency power source 62 constitutes an example of a plasma generating unit.

The bias power source 64 is a power source for generating an electrical bias. The bias power source 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 in the range of 400kHz to 13.56MHz. When the electrical bias is used together with the high frequency power HF, it is applied to the substrate holder 14 to feed ions to the substrate W. In one example, the electrical bias is applied to the lower electrode 18. If the electrical bias is applied to the lower electrode 18, the potential of the substrate W placed on the substrate holder 14 changes within a period specified by the second frequency. Furthermore, an electrical bias can also be imparted to the bias electrode disposed within the electrostatic chuck 20.

In one embodiment, the electrical bias may also be a high-frequency power LF having a 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 to the substrate W. The bias power source 64 configured to generate the high-frequency power LF is connected to the lower electrode 18 via the matcher 68 and the electrode plate 16. The matcher 68 has a circuit for matching the impedance of the load side (lower electrode 18 side) of the bias power source 64 with the output impedance of the bias power source 64.

Furthermore, 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 high-frequency power LF may be greater than 13.56 MHz, for example, 40 MHz. Furthermore, in this case, the substrate processing device 1 may not have the high-frequency power supply 62 and the matching device 66. In this case, the bias power supply 64 constitutes an example of a plasma generating unit.

In another embodiment, the electrical bias may also be a pulse voltage (pulse voltage). In this case, the bias power source may be a DC power source. The bias power source may be configured as a power source itself supplying a pulse voltage, or may be configured as a device for pulsing the voltage on the downstream side of the bias power source. In one example, the pulse voltage is applied to the lower electrode 18 in a manner that generates a negative potential on the substrate W. The pulse voltage may be a rectangular wave, a triangular wave, a surge wave, or may have other waveforms.

The period of the pulse voltage is determined by the second frequency. The period of the pulse voltage includes two periods. The pulse voltage in one of the two periods is a negative voltage. The voltage level (i.e., absolute value) in one of the two periods is higher than the voltage level (i.e., absolute value) in the other period. The voltage in the other period can be either negative or positive. The negative voltage level in the other 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 an electrode plate 16. Furthermore, the bias power source 64 can also be connected to the bias electrode disposed in the electrostatic chuck 20 instead of the lower electrode 18.

In one embodiment, the bias power source 64 can also provide a continuous wave of electrical bias to the lower electrode 18. That is, the bias power source 64 can also continuously provide the electrical bias to the lower electrode 18.

In another embodiment, the bias power supply 64 may also impart an electrical bias pulse to the lower electrode 18. The electrical bias pulse may be periodically imparted to the lower electrode 18. The period of the electrical bias pulse is determined by the third frequency. The third frequency is lower than the second frequency. The third frequency is, for example, greater than 1 Hz and less than 200 kHz. In another example, the third frequency may also be greater than 5 Hz and less than 100 kHz.

The cycle of the electrical bias pulse includes two periods, namely, the H period and the L period. The level of the electrical bias in the H period (i.e., the level of the electrical bias pulse) is higher than the level of the electrical bias in the L period. That is, the electrical bias pulse can be applied to the lower electrode 18 by increasing or decreasing the level of the electrical bias. The level of the electrical bias in the L period can also be greater than zero. Alternatively, the level of the electrical bias in the L period can also be zero. That is, the electrical bias pulse can also be applied to the lower electrode 18 by alternately switching the supply of the electrical bias to the lower electrode 18 and stopping the supply. Here, when the electrical bias is high-frequency power LF, the level of the electrical bias is the power level of the high-frequency power LF. When the electrical bias is high-frequency power LF, the level of the high-frequency power LF in the pulse of the electrical bias may be 2kW or more. When the electrical bias is a pulse of a negative-polarity DC voltage, the level of the electrical bias is the effective value of the absolute value of the negative-polarity DC voltage. The duty ratio of the pulse of the electrical bias, i.e., the ratio of the H period to the cycle of the pulse 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 can be greater than 5% and less than 50%. Alternatively, the duty ratio of the pulse wave of the electrical bias can also be greater than 50% and less than 99%. Furthermore, during the period of supplying the electrical bias, the L period is equivalent to the first period mentioned above, and the H period is equivalent to the second period mentioned above. Furthermore, the level of the electrical bias during the L period is equivalent to the 0 or first level mentioned above, and the level of the electrical bias during the H period is equivalent to the second level mentioned above.

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

In another embodiment, the high-frequency power source 62 can also supply a pulse wave of high-frequency power HF. The pulse wave of high-frequency power HF can be supplied periodically. The period of the pulse wave of high-frequency power HF is determined 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 period of the pulse wave of high-frequency power HF includes two periods, namely 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 in the L period can be greater than zero or zero. Furthermore, during the period of supplying high-frequency power HF, the L period is equivalent to the third period mentioned above, and the H period is equivalent to the fourth period mentioned above. Furthermore, the level of high-frequency power HF during the L period is equivalent to the 0 or third level mentioned above, and the level of the electrical bias during the H period is equivalent to the fourth level mentioned above.

Furthermore, the cycle of the pulse of the high-frequency power HF may be synchronized with the cycle of the pulse of the electrical bias. The H period in the cycle of the pulse of the high-frequency power HF may be synchronized with the H period in the cycle of the pulse of the electrical bias. Alternatively, the H period in the cycle of the pulse of the high-frequency power HF may be asynchronous with the H period in the cycle of the pulse of the electrical bias. The length of the H period in the cycle of the pulse of the high-frequency power HF may be the same as or different from the length of the H period in the cycle of the pulse of the electrical bias. One of the H periods in the cycle of the high-frequency power HF pulse wave Part or all of it may also overlap with the H period in the cycle of the electrical bias pulse wave.

FIG2 is a timing diagram showing an example of high-frequency power HF and an electrical bias. FIG2 is an example in which both high-frequency power HF and an electrical bias use pulse waves. In FIG2, the horizontal axis represents time. In FIG2, the vertical axis represents the power levels of the high-frequency power HF and the electrical bias. "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 the electrical bias is not supplied or is lower than the power level indicated by "H2". When the electrical bias is a pulse 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 magnitude of the power level of the high-frequency power HF and the electrical bias in Figure 2 does not represent the relative relationship between the two and can be set arbitrarily. Figure 2 is an example in which the cycle of the pulse of the high-frequency power HF is synchronized with the cycle of the pulse of the electrical bias and the duration of the H period and L period of the pulse of the high-frequency power HF is the same as the duration of the H period and L period of the pulse of the electrical bias.

Return to Figure 1 to continue the explanation. The substrate processing device 1 is further equipped with a power supply 70. The power supply 70 is connected to the upper electrode 30. In one example, the power supply 70 can be configured to supply a DC voltage or a low-frequency power to the upper electrode 30 during plasma processing. For example, the power supply 70 can supply a negative DC voltage to the upper electrode 30, or can periodically supply low-frequency power. The DC voltage or the low-frequency power can be supplied in the form of a pulse wave, or in the form of a continuous wave. In this embodiment, the positive ions existing in the plasma processing space within 10s are fed into the upper electrode 30 and collide with it. Thus, secondary electrons are released from the upper electrode 30. The released secondary electrons modify the mask film MK, thereby improving the etching resistance of the mask film MK. In addition, the secondary electrons help to increase the plasma density. In addition, the charged state of the substrate W is neutralized by the irradiation of the secondary electrons, thereby improving the straightness of the ions into the recess formed by etching. Furthermore, when the upper electrode 30 contains a silicon-containing material, silicon is released together with the secondary electrons by the collision of the positive ions. The released silicon bonds with the oxygen in the plasma to form a silicon oxide compound, and is deposited on the mask to function as a protective film. Based on the above, by supplying DC voltage or low-frequency power to the upper electrode 30, not only the selectivity is improved, but also the shape abnormality of the concave portion formed by etching and the etching rate can be suppressed and improved.

When plasma processing is performed in the substrate processing device 1, gas is supplied from the gas supply unit to the internal space 10s. In addition, 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 electrical bias. The generated high-frequency electric field generates plasma from the gas in the internal 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 memory, an input device, a display device, a signal input/output interface, and the like. The control unit 80 controls each unit of the substrate processing apparatus 1. In the control unit 80, an operator may use an input device to input instructions, etc., to manage the substrate processing apparatus 1. Moreover, in the control unit 80, the operating status of the substrate processing apparatus 1 may be visualized and displayed by a display device. Furthermore, a control program and process recipe data are stored in the memory unit. The control program is executed by a processor to perform various processes in the substrate processing apparatus 1. The processor executes the control program to control each unit of the substrate processing apparatus 1 according to the process recipe data. In an exemplary embodiment, part or all of the control unit 80 may be configured as a part of a device external to the substrate processing device 1.

<Composition of substrate processing system PS>

FIG3 is a diagram schematically showing a substrate processing system PS of an exemplary implementation method. The present processing method can also be performed using the substrate processing system PS.

The substrate processing system PS has substrate processing chambers PM1 to PM6 (hereinafter, collectively referred to as "substrate processing modules PM"), a transfer module TM, loading lock modules LLM1 and LLM2 (hereinafter, collectively referred to as "loading lock modules LLM"), a carrier module LM, and loading ports LP1 to LP3 (hereinafter, collectively referred to as "loading ports LP"). The control unit CT controls the components of the substrate processing system PS and performs specific processing on the substrate W.

The substrate processing module PM performs etching processing, trimming processing, film forming processing, annealing processing, doping processing, lithography processing, cleaning processing, ashing processing, etc. on the substrate W. A part of the substrate processing module PM can be a measurement module, and can 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 device 1 shown in FIG. 1 is an example of the substrate processing module PM.

The transport module TM has a transport device for transporting substrates W, and transports substrates W between substrate processing modules PM or between substrate processing module PM and loading lock module LLM. The substrate processing module PM and loading lock module LLM are arranged adjacent to the transport module TM. The transport module TM, substrate processing module PM and loading lock module LLM are spatially isolated or connected by an openable and closable gate.

The load lock module LLM1 and LLM2 are arranged between the transport module TM and the carrier module LM. The load lock module LLM can switch the pressure inside it to atmospheric pressure or vacuum. The load lock module LLM transports the substrate W from the carrier module LM with atmospheric pressure to the transport module TM with vacuum, and also transports it from the transport module TM with vacuum to the carrier module LM with atmospheric pressure.

The carrier module LM has a transfer device for transferring substrates W, and transfers substrates W between the loading lock module LLM and the loading port LP. The interior of the loading port LP can be used to load, for example, a FOUP (Front Opening Unified Pod) that can accommodate 25 substrates W or an empty FOUP. The carrier module LM takes out the substrate W from the FOUP in the loading port LP and transfers it to the loading lock module LLM. In addition, the carrier module LM takes out the substrate W from the loading lock module LLM and transfers it to the FOUP in the loading port LP.

The control unit CT controls the components of the substrate processing system PS to perform specific processing on the substrate W. The control unit CT stores a process recipe that sets the process steps, process conditions, and transport conditions, and controls the components of the substrate processing system PS according to the process recipe to perform specific processing on the substrate W. The control unit CT can also have part or all of the functions of the control unit 80 of the substrate processing device 1 shown in Figure 1.

<An example of substrate W>

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

The base film UF may be, for example, a silicon wafer or an organic film, a dielectric film, a metal film, a semiconductor film, etc. formed on a silicon wafer. The base film UF may be composed of a plurality of film layers.

The dielectric film DF may be a silicon-containing film. The silicon-containing film may be, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film (SiON film), or a Si-ARC film. The dielectric film DF may include a polysilicon film. The dielectric film DF may be formed by a plurality of film stacks. For example, the dielectric film DF may be formed by alternately stacking a silicon oxide film and a polysilicon film. In one example, the dielectric film DF is a stacked film obtained by alternately stacking a silicon oxide film and a silicon nitride film.

The base film UF and/or the dielectric film DF can be formed by CVD (Chemical Vapor Deposition) method, spin coating method, etc. The base film UF and/or the dielectric film DF can be a flat film or a film with concave and convex surfaces.

The 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 side wall S1 of the mask film MK. That is, in FIG. 4 , the dielectric film DF has an area covered by the mask film MK and an area 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 top to bottom in FIG. 4 ). The shape may be, for example, a hole shape, a line shape, or a combination of a hole shape and a line shape. The mask film MK may also have a plurality of side walls S1, and a plurality of openings OP are defined by the plurality of side walls S1. The plurality of openings OP may also have a line shape, and be arranged at fixed intervals to form a line and space pattern. Furthermore, the plurality of openings OP may also 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 may be, for example, a spin-on carbon film (SOC), an amorphous carbon film, or a photoresist film. The metal-containing film may include, for example, tungsten, tungsten carbide, or titanium nitride. The mask film MK may be formed by CVD, spin coating, or the like. The opening OP may be formed by etching the mask film MK. The mask film MK may 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 on the base film UF as a dielectric film DF. In another example, the substrate W may have a polycrystalline silicon film, silicon boride or tungsten carbide as a mask film MK on the silicon nitride film. In another example, the mask film MK may be a multilayer anti-etching agent including a polycrystalline silicon film, silicon boride or tungsten carbide. In one example, the multilayer anti-etching agent has a mask including a hard mask on the polycrystalline silicon film. In one example, the hard mask has a silicon oxide film (TEOS (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 treatment method>

FIG5 is a flow chart showing the processing method. The processing method includes a process of preparing a substrate (step ST1) and an etching process (step ST2). Hereinafter, the processing method is described by taking the control unit 80 shown in FIG1 to control each part of the substrate processing device 1 and executing the processing method on the substrate W shown in FIG4 as an example.

(Step ST1: Preparation of substrate)

In step ST1, a substrate W is prepared in the inner space 10s of the chamber 10. In the inner space 10s, the substrate W is arranged on the upper surface of the substrate holder 14 and is held by the electrostatic chuck 20. At least a part of the process of forming each component of the substrate W can be performed in the inner space 10s. In addition, after all or part of each component of the substrate W is formed in a device or chamber outside the substrate processing device 1, the substrate W can be moved into the inner space 10s and arranged 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 process of supplying a processing gas (step ST21) and a process of generating plasma (step ST22). The dielectric film DF is etched by active species (ions, free radicals) of the plasma generated from the processing gas.

In step ST21, a processing gas is supplied from the gas supply unit into the inner space for 10 seconds. The processing gas includes a reaction gas containing a fluorine- _containing gas and a _CxHyFz ( _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 is also referred to as _{" CxHyFz gas} "). In this embodiment, unless otherwise stated, the reaction gas does not contain noble gases such as Ar.

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

As the _CxHyFz gas _, for example _{, CxHyFz} (x is an integer greater than or equal to 2, and y and _z are integers greater than or equal to 1) _gas can be used. As the _CxHyFz (x is an integer greater than _or equal to 2, _and y _and z are integers greater _{than or equal to 1) gas, specifically, at least one gas selected from the group consisting of C2HF5 gas, C2H2F4 gas , C2H3F3 gas , C2H4F2 gas , C3HF7 gas , C3H2F2 gas , C3H2F4 gas , C3H2F6 gas , C3H3F5 gas , C4H2F6 gas , C4H5F5} gas, _{C4H2F8 gas , C5H2F6 gas , C5H2F10 gas and C5H3F7 gas can be} used _. In one example, as the _{CxHyFz gas} , at least _one selected from _the group consisting _{of C3H2F4 gas, C3H2F6 gas , C4H2F6 gas} , and _C4H2F8 gas _{is used} . In another example, _{as the CxHyFz} gas, at least one selected from _{the group consisting of C3H2F4 gas, C3H2F6 gas , C4H2F6 gas , C4H2F8 gas , and C5H2F6 gas is used} . When _C4H2F6 gas _{is used} as _{the CxHyFz gas} , for example, _{C4H2F6 may} be in a _{linear chain} or _{a ring shape} .

The plasma generated from _the processing gas containing _{CxHyFz gas} contains _CxHyFz species dissociated from the _{CxHyFz gas .} The _CxHyFz species contain a large number of _{CxHyFz radicals containing two or more carbon atoms (for example, C2H2F radicals , C2H2F2} radicals, _{C3HF3 radicals} , hereinafter referred _{to as " CxHyFz - based radicals} ") _{. The CxHyFz} radicals form a protective film on the surface of the mask film MK to protect the surface. The protective film can _suppress the etching of _the mask film MK when the _dielectric film _DF is etched. Therefore, the _{CxHyFz radicals} can improve the selectivity of the dielectric film _DF with respect to the mask film MK in etching the dielectric film DF (the value obtained by dividing the etching rate of the dielectric film DF by the etching rate of the mask film MK).

In addition, the plasma generated from _the treatment gas containing _{CxHyFz gas} contains a large amount of HF species that are dissociated from _{the CxHyFz gas} and/or further dissociated from _CxHyFz -based radicals. The HF species contains at least any one of hydrogen _{fluoride gas} , radicals, and ions. The HF species functions 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 _CxHyFz gas may have one or more _{CF3 groups} . When the _CxHyFz gas has _{a CF3} group, for example, when a _CH group and a _CF3 group form a single bond, _it is easily dissociated into HF due to its molecular structure, thereby increasing HF species in the plasma.

Furthermore, the processing gas may include _CxFz (x is an integer greater than or equal to 2, _and z is an integer greater than or equal to 1 ₎ gas instead of part or all of _{the CxHyFz} gas. Specifically, at least _one selected from the group consisting of _C2F2 , _{C2F4 , C3F8 , C4F6} , _{C4F8 ,} and _C5F8 may be used. In this way, the amount of hydrogen in _{the plasma} can be suppressed, for example, the morphological deterioration caused by excessive hydrogen or the increase of moisture in the chamber 10 can be suppressed. Here, the so-called morphology refers to the surface state of the mask film MK, the roundness of the opening OP, and other characteristics related to the shape of the mask.

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

The reaction gas may include a halogen-containing gas. The halogen-containing gas 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 the chlorine-containing gas, gases such as 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 the like may 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 , BBr ₃ and the like may be used. As the iodine-containing gas, HI, _CF3I , _{C2F5I , C3F7I} , _IF5 , _IF7 , _I2 , _PI3 and _the like can be used. In one example, as the halogen-containing gas, at least one selected from the group consisting of _Cl2 gas, _Br2 gas, HBr gas, _CF3I gas, _IF7 gas and _C2F5Br gas is used _. In another example, as the halogen-containing gas, _Cl2 gas and HBr gas are used.

The reaction gas may also include a nitrogen-containing gas. The nitrogen-containing gas can suppress the 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 reaction gas may include an oxygen-containing gas. As with the nitrogen-containing gas, the oxygen-containing gas can suppress 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 O2} , CO, _CO2 , _H2O , and _H2O2 can be used. In one example, the reaction gas includes an oxygen-containing gas other than _H2O , that is, at least one gas selected from the group consisting of _O2 , _CO , _CO2 , and _H2O2 . The oxygen-containing gas causes less damage to the mask film MK, and can suppress morphological degradation.

FIG. 6 is a diagram showing an example of the shape of the mask film MK after etching. FIG. 6 is an example of the shape of the mask film MK (top view) when etching a sample substrate having the same structure as the substrate W in the substrate processing device 1. In FIG. 6, "No." indicates the sample number of the sample substrate after etching. "Processing gas" indicates the processing gas used during etching, and "A" indicates _a processing gas including _{HF gas, C4H2F6 gas} , _O2 gas, _NF3 gas, HBr gas and _Cl2 gas (hereinafter referred to as "processing gas A"). Processing gas A includes HF gas of 80 volume % or more relative to the total flow rate of the reaction gas, and includes _O2 gas of 4 to 5 volume % relative to the total flow rate of the reaction gas. "B" of "processing gas" indicates a processing gas that is the same as processing gas A except that NF ₃ gas is not contained and the flow rate of O ₂ gas is increased accordingly (hereinafter referred to as "processing gas B"). Processing gas B contains 6-7 volume % of O ₂ gas relative to the total flow rate of the reaction gas. "Yes" of "upper electrode application" indicates that a negative polarity DC voltage is supplied to the upper electrode 30 of the substrate processing device 1 during etching, and "No" indicates that a negative polarity DC voltage is not supplied to the upper electrode 30. According to the "mask shape" in Figure 6, in the "yes" and "no" cases of "upper electrode application", when the treatment gas A containing NF ₃ is used (samples 1 and 3), the true roundness of the opening OP will deteriorate and a step difference will be generated on the surface of the mask film MK. On the other hand, when the treatment gas B containing no NF ₃ gas and with an increased flow rate of O ₂ gas is used (samples 2 and 4), the true roundness of the opening OP is higher, and no step difference will be generated on the surface of the mask film MK. Compared with the case of using the treatment gas A (samples 1 and 3), the morphology of the mask film MK is improved.

The reaction gas may include a phosphorus-containing gas. As the phosphorus-containing gas, for example, at least one gas selected from _the group consisting of _PF3 , _PF5 , _POF3 , _{HPF6, PCl3 , PCl5} , _POCl3 , _PBr3 , _PBr5 , _POBr3 , _PI3 , _P4O10 , _P4O8 , _P4O6 , _PH3 , _Ca3P2 , _H3PO4 , and _{Na3PO4 may be} used. Among them, gases containing _phosphorus halides such as _PF3 , _PF5 , and _PCl3 may be used _{, and} gases containing phosphorus fluorides such as _PF3 and _PF5 may also be used.

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

In addition to the above-mentioned reaction gases, the processing gas may also include inert gas (noble gas such as Ar).

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

Then, in step ST22, high-frequency power and/or electrical bias are supplied from the plasma generating unit (high-frequency power source 62 and/or bias power source 64). Thus, a high-frequency electric field is generated between the upper electrode 30 and the substrate support 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 to the substrate W and the substrate W is etched.

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

FIG7 is a diagram showing an example of the temperature dependence of etching. FIG7 shows the experimental results obtained by etching a silicon oxide film using a plasma processing device 1 to generate plasma from a processing gas that is a mixed gas of hydrogen fluoride gas and argon gas. In this experiment, the silicon oxide film is etched while changing the temperature of the substrate holder 14, and a quadrupole mass analyzer is used to measure the amount of hydrogen fluoride (HF) and the amount of SiF ₃ in the gas phase during the etching of the silicon oxide film. The horizontal axis of FIG7 represents the temperature T (°C) of the substrate holder 14, and the vertical axis represents the amount of hydrogen fluoride (HF) and SiF ₃ (intensity standardized with helium as the reference).

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 the amount of _SiF3 , a reaction product generated by etching the silicon oxide film, increases. That is, in this experiment, when the temperature of the substrate holder 14 is about -60°C or lower, the amount of the etchant used in etching the silicon oxide film increases.

Therefore, according to the experiment, the lower the temperature of the substrate holder 14 is, the more the etching of the silicon oxide film is promoted, and therefore, the selectivity of the dielectric film DF to the mask film MK can be improved. Furthermore, the temperature at which the amount of the etchant is increased varies according to the relationship with the flow ratio of the hydrogen fluoride gas in the reaction gas or the processing conditions such as the added gas. Therefore, the relationship between the temperature of the substrate holder 14 and the amount of hydrogen fluoride and the amount of _SiF3 can also be investigated under specific conditions, and the temperature of the substrate holder 14 can be set based on the results.

FIG8 is a diagram showing an example of the cross-sectional structure of the substrate W in step ST22. When executing step ST22, 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 (the direction from top to bottom in FIG8) to form a recess RC. 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 can be greater than 20, or greater than 30, greater than 40, greater than 50, or greater than 100.

In the present treatment method, the reaction gas includes _{CxHyFz gas . CxHyFz gas} generates _CxHyFz -based free _radicals at high density in plasma. _CxHyFz -based free radicals are adsorbed on the surface (upper surface T1 and side _{wall S1 )} of the mask film MK or the side wall S2 of the dielectric film DF to form a protective film PF. Furthermore, the protective film _PF can be thinned toward the depth direction (the 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 performing step ST22 (i.e., the etching rate of the mask film MK is increased). Thereby, the selectivity of the dielectric film DF relative to the mask film MK is improved.

The protective film PF can suppress the lateral etching (left _{and right direction of FIG. 8 ) of the dielectric film DF. When the flow rate of the CxHyFz gas} is less than 20 volume % relative to the total flow rate of the reaction _gas , excessive deposition of carbon on the side wall S1 of the mask film MK and/or the dielectric film DF, which causes clogging of the opening OP of the mask film MK, can be further suppressed. When the reaction gas contains an oxygen-containing gas, excessive deposition of carbon on the side wall S1 of the mask film MK and/or the dielectric film DF, which causes clogging of the opening OP of the mask film MK, can be further suppressed. 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.

The _CxHyFz gas generates a large amount of _HF species in the plasma. Therefore, when executing step ST22, the HF species (etchant) can be sufficiently supplied even to the bottom BT of the recess RC formed in the dielectric film _DF . In addition, when executing step ST22, the temperature of the substrate holder 14 is controlled to be a low temperature below 0°C. By suppressing the increase in the temperature of the substrate W, the adsorption of the HF species (etchant) at the bottom BT of the recess RC can be promoted (the adsorption coefficient of the HF species is further increased at a low temperature). By 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 10s, the bias power source 64 can periodically apply an electrical bias pulse to the substrate support 14. By periodically applying an electrical bias pulse, etching and formation of the protective film PF can be performed alternately.

Furthermore, when executing step ST2, the flow rate _of the _{CxHyFz gas} supplied to the internal space 10s may be changed. For example, after the first etching is performed using the reaction gas including _{the CxHyFz gas} with the first partial pressure, the second etching may be performed using the reaction gas including the _{CxHyFz gas} with the second partial pressure. Thus, for example, when the dielectric film DF is a laminated film of different materials, the laminated film _may be appropriately etched by controlling the flow rate of _{the CxHyFz gas in} combination with the material of the film to be etched.

Furthermore, when executing step ST2, _{the flow rate of the CxHyFz gas supplied} to the inner space 10s may be different at the center and the periphery of the substrate W when looking down at the substrate W. Thus, even when the size of the opening OP surrounded by the side wall S1 of the mask film MK is different at the center and the periphery of the substrate W, the deviation of the size can be corrected by controlling the distribution of the flow rate _of the _{CxHyFz gas} .

Furthermore, when executing step ST2, the pressure in the chamber 10 (internal space 10s) or the electrical bias supplied to the substrate holder 14 from the bias power supply 64 may be changed. For example, step ST2 may include: a first process, which is to set the chamber 10 to a first pressure, supply the first electrical bias to the substrate holder 14 to etch the dielectric film DF; and a second process, which is to set the chamber 10 to a second pressure, supply the second electrical bias to the substrate holder 14 to etch the dielectric film DF. Step ST2 may also alternately repeat the first process and the second process. The first pressure may be different from the second pressure, for example, it may be greater than the second pressure. The first electrical bias may be different from the second electrical bias, for example, the absolute value of the first electrical bias may 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, the dielectric film DF may be anisotropically etched before or just before the recess RC reaches the base film UF in the first process, and the dielectric film DF may be isotropically etched in the second process in such a manner that the bottom of the recess RC is expanded in the horizontal direction.

The following describes various experiments conducted to evaluate this treatment method. The present invention is not limited to the following experiments.

(Experiment 1)

FIG. 9 is a graph showing the measurement results of Experiment 1. In Experiment 1, the generation amount of HF species 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 as reaction gases to the inner space of the substrate processing apparatus 1 for 10 seconds to generate plasma for 10 minutes, and the HF intensity before and after the plasma generation was measured using a quadrupole mass analyzer. The temperature of the substrate holder 14 was set to -40°C. The vertical axis of FIG. 9 represents the difference between the HF intensity before the plasma generation and the HF intensity after the plasma generation. The larger the value on the vertical axis, the more HF species are generated in the plasma.

As shown in FIG. 9 , the C ₄ H ₂ F ₆ gas of one embodiment of the reaction gas of the present treatment method generates more HF species in the plasma, obviously compared with the C ₄ F ₈ gas and the C ₄ F ₆ gas not containing hydrogen, and even compared with the CH ₂ F ₂ gas containing hydrogen.

(Experiment 2)

Fig. 10 and Fig. 11 are diagrams showing the measurement results of Experiment 2. In Experiment 2, the etching rate and the selectivity 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 had silicon oxide as a dielectric film DF on a silicon film, and had an organic film as a mask film MK. Processing gas was supplied to the internal space 10s of the substrate processing device 1 to generate plasma, and the dielectric film DF of the sample substrate was etched. The temperature of the substrate holder 14 was set to -40°C. As shown in FIG. 10 and FIG. 11, when the reaction gas in the process gas includes any one of C ₄ F ₈ gas, CH ₂ F ₂ gas or C ₄ H ₂ F ₆ gas, the etching rate (E/R [nm/min], FIG. 10) of the dielectric film DF and the selectivity (Sel., FIG. 11) of the dielectric film DF to the mask film MK are measured. The flow rate of _{C 4} F ₈ gas is 5 volume % of the total flow rate of the reaction gas. The flow rate of CH ₂ F ₂ gas is 15 volume % of the total flow rate of the reaction gas. The flow rate of C ₄ H ₂ F ₆ gas is 5 volume % of the total flow rate of the reaction gas. The reaction gas includes HF gas at 70-90 volume % relative to the total flow rate of the reaction gas.

As shown in FIG. 10 and FIG. 11 , the processing gas including C ₄ H ₂ F ₆ gas as one embodiment of the reaction gas of the present processing method has a higher etching rate and a higher selectivity than the processing gas including C ₄ F ₈ gas or CH ₂ F ₂ gas as the reaction gas.

(Experiment 3)

FIG. 12 and FIG. 13 are diagrams showing the measurement results of Experiment 3. In Experiment 3, the etching rate and the bow CD (Critical Dimension) under various processing gases when the aspect ratio of the concave portion RC is changed are measured. In Experiment 3, a sample substrate having the same structure as that of Experiment 2 is prepared on a substrate holder 14. Processing gas is supplied to the internal space of the substrate processing device 1 for 10 seconds to generate plasma, and the dielectric film DF of the sample substrate is etched. The temperature of the substrate holder 14 is set to -40°C. FIG. 12 and FIG. 13 show the relationship between the selectivity (Sel., FIG. 12 _{) of} the dielectric film DF relative to the mask film MK and the maximum width (bow CD: CD _m [nm], FIG. ₁₃ ) of the _recess RC of the dielectric film DF when the aspect ratio (AR) of the recess RC is changed for each case where the reactive gas in the process gas includes C 4 _F 8 gas or C 4 H 2 F 6 gas. The selectivity can be obtained by dividing the etching rate of the dielectric film DF by the etching rate of the mask film MK. _{The C 4} F ₈ gas or C ₄ H ₂ F ₆ gas is 5 volume % of the total flow rate of the reactive gas. The reactive gas includes HF gas at a volume % or more relative to the total flow rate of the reactive gas.

As shown in FIG. 12 and FIG. 13, when the reaction gas including C ₄ H ₂ F ₆ gas is used as one embodiment of the process gas of the present process method, even if the aspect ratio of the recessed portion RC formed in the dielectric film DF becomes higher, a higher selectivity is maintained compared to when the reaction gas including C ₄ F ₈ gas is used, and an increase in the bow CD is suppressed.

(Experiment 4)

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

As shown in FIG. 14 , the CO intensity in CH1 reaches a peak value immediately after the cleaning starts, then decreases rapidly and becomes 0 20 to 30 seconds after the cleaning starts. The CO intensity in CH2 has a lower peak value than that in CH1, and the decrease is also gentle, and does not become 0 even 200 seconds after the cleaning starts. That is, when a treatment gas including C ₄ H ₂ F ₆ gas, which is one embodiment of the reaction gas of the present treatment method, is used, the cleaning time of the chamber after etching can be shortened compared to when a treatment gas including CH ₂ F ₂ gas is used.

Furthermore, the disclosed implementation method further includes the following aspects.

(Note 1)

An etching gas composition comprises _HF gas and _{a reaction gas of at least one CxHyFz gas selected from the group consisting of C4H2F6 gas, C4H2F8 gas, C3H2F4 gas and C3H2F6 gas , wherein the flow rate of the HF gas} is greater than _{that of the CxHyFz gas .}

(Note 2)

In the etching gas composition of Note 1, the flow rate _{of the CxHyFz gas is} less than 20 volume % relative to the total flow rate of the reaction gas.

(Note 3)

For example, in the etching gas composition of Note 1 or 2, the flow rate of the above-mentioned HF gas is more than 70 volume % relative to the total flow rate of the above-mentioned reaction gas.

(Note 4)

The etching gas composition as in any one of Notes 1 to 3, wherein the reaction gas further comprises a gas containing a halogen.

(Note 5)

As in the etching gas composition of Note 4, the halogen-containing gas is at least one selected from the group consisting of chlorine-containing gas, bromine-containing gas and iodine-containing gas.

(Note 6)

The etching gas composition of Appendix 4, wherein the halogen-containing gas is at least _one selected from _the group consisting of _Cl2 , SiCl2, _SiCl4 , _CCl4 , _SiH2Cl2 , _Si2Cl6 , _{CHCl3 , SO2Cl2} , _BCl3 , _PCl3 , _{PCl5 , POCl3} , _Br2 , _HBr , _CBr2F2 , _C2F5Br , _PBr3 , _PBr5 , _POBr3 , _BBr3 , _HI , _CF3I , _{C2F5I , C3F7I} , _IF5 , _IF7 , _I2 and _{PI3 .}

(Note 7)

An etching gas composition as described in any one of Notes 1 to 5, wherein the reaction gas comprises a phosphorus-containing gas.

(Note 8)

An etching gas composition as described in any one of Notes 1 to 7, wherein the reaction gas further comprises an oxygen-containing gas.

(Note 9)

An etching gas composition as described in any one of Notes 1 to 8, wherein the reaction gas further comprises at least one selected from the group consisting of boron-containing gas and sulfur-containing gas.

This processing method can be modified in various ways without departing from the scope and purpose of the present invention. For example, in addition to being executed using a capacitively coupled substrate processing device 1, this processing method can also be executed using a substrate processing device that uses any plasma source such as an inductively coupled plasma or microwave plasma.

Claims (28)

A substrate processing method comprises the following steps: preparing a substrate having a dielectric film on a substrate holder in _a chamber; and etching the dielectric _film by generating plasma _{from a reaction gas comprising HF gas and at least one CxHyFz gas selected from the group consisting of C4H2F6 gas , C4H2F8 gas , C3H2F4 gas and C3H2F6 gas ; and} in the etching step, the temperature of the substrate holder is set to be below 0°C, and the flow rate of the HF gas is greater than the flow rate of _{the CxHyFz gas .} In the substrate processing method of claim 1, the flow rate of the C _x H _y F _z gas is less than 20 volume % relative to the total flow rate of the reaction gas. In the substrate processing method of claim 1 or 2, the flow rate of the HF gas is greater than 70 volume % relative to the total flow rate of the reaction gas. The substrate processing method of claim 1 or 2, wherein the reaction gas further comprises a gas containing halogen. In the substrate processing method of claim 4, the halogen-containing gas is at least one selected from the group consisting of chlorine-containing gas, bromine-containing gas and iodine-containing gas. A substrate processing method as claimed in claim 4, wherein the halogen-containing gas _is at least _one gas selected from _the group consisting of _Cl2 , SiCl2, _SiCl4 , _CCl4 , _SiH2Cl2 , _{Si2Cl6 , CHCl3} , _SO2Cl2 , _BCl3 , _{PCl3 , PCl5} , _POCl3 , _Br2 , _HBr , _CBr2F2 , _C2F5Br , _PBr3 , _PBr5 , _POBr3 , _BBr3 , _HI , _CF3I , _{C2F5I , C3F7I} , IF5, _IF7 , _I2 and _{PI3 .} The substrate processing method of claim 1 or 2, wherein the reaction gas comprises a phosphorus-containing gas. The substrate processing method of claim 1 or 2, wherein the reaction gas comprises an oxygen-containing gas. In the substrate processing method of claim 1 or 2, the reaction gas further comprises at least one selected from the group consisting of boron-containing gas and sulfur-containing gas. A substrate processing method as claimed in claim 1 or 2, wherein the plasma is generated from a processing gas comprising the reactive gas and an inert gas. A substrate processing method as claimed in claim 1 or 2, wherein the dielectric film comprises a silicon film. A substrate processing method as claimed in claim 11, wherein the silicon-containing film comprises at least one selected from the group consisting of a silicon oxide film, a silicon nitride film and a polycrystalline silicon film. A substrate processing method as claimed in claim 1 or 2, wherein the substrate has a mask which defines at least one opening on the dielectric film and comprises an organic film or a metal-containing film. The substrate processing method of claim 1 or 2, wherein the etching process includes the step of applying an electrical bias to the substrate support, The period of applying the electrical bias to the substrate support includes a first period and a second period alternating with the first period, and The electrical bias in the first period is 0 or a first level, and the electrical bias in the second period is a second level greater than the first level. The substrate processing method of claim 14, wherein the etching process includes the step of supplying high-frequency power for generating plasma to the substrate support or the upper electrode opposite to the substrate support, the period of supplying the high-frequency power includes the third period and the fourth period alternating with the third period, the level of the high-frequency power in the third period is 0 or the third level, the level of the high-frequency power in the fourth period is the fourth level greater than the third level, and the second period and the fourth period at least partially overlap. A substrate processing method as claimed in claim 14, wherein the electrical bias is a pulse voltage. A substrate processing method as claimed in claim 1 or 2, wherein the etching process includes the step of supplying a direct current voltage or a low-frequency power to an upper electrode opposite to the substrate holder. A substrate processing method as claimed in claim 1 or 2, wherein the etching process comprises: A first process, which is to set the chamber to a first pressure, supply a first electrical bias to the substrate holder to etch the dielectric film; and A second process, which is to set the chamber to a second pressure, supply a 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. A substrate processing method as claimed in claim 18, wherein the first pressure is greater than the second pressure. A substrate processing method as claimed in claim 18, 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. A substrate processing method as claimed in claim 18, wherein the above-mentioned first step and the above-mentioned second step are repeated alternately. A substrate processing method comprises the following steps: preparing a substrate having a silicon-containing film including a silicon oxide film on a substrate holder in a chamber; and etching the silicon-containing film by generating plasma from a reaction _gas including a fluorine- _{containing gas and CxHyFz (} a gas different from the fluorine-containing gas, x is an integer greater than 2, and y and z are integers greater than 1); and in the etching step, the temperature of the substrate holder is set to be below 0°C, and _the flow rate of _{the CxHyFz} gas is below 20 volume % relative to the total flow rate of the reaction gas. A substrate processing method as claimed in claim 22, wherein the fluorine-containing gas can generate a gas of HF species in the chamber. The substrate processing method _{of claim 22 or 23, wherein the CxHyFz gas} has more than one _{CF3 group} . _The substrate processing method _of claim 24, wherein the _{CxHyFz gas} comprises at least one selected from _{the group consisting of C3H2F4 gas} , _{C3H2F6 gas , C4H2F6 gas} , _{C4H2F8 gas and C5H2F6 gas .} A substrate processing method as claimed in claim 22 or 23, wherein among the reaction gases, the fluorine-containing gas has the largest flow rate. A 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; generating plasma in the chamber; and _etching the silicon-containing film using _{HF species and CxHyFz (} x is an integer greater than 2, y and z are integers greater than 1) species contained in the plasma; and the amount of the HF species in the plasma is the largest. A substrate processing apparatus comprises a chamber, a substrate holder disposed in the chamber and configured to adjust the temperature thereof, a plasma generating unit for supplying power for generating plasma in the chamber, and a control unit, wherein the control unit performs the following control for etching a dielectric film of a substrate supported on the substrate holder, that is, by introducing _a reaction gas including HF gas and at least _{one CxHyFz} gas selected from the group consisting of _{C4H2F6 gas} , _C4H2F8 gas _{, C3H2F4} gas and _C3H2F6 gas into the chamber _by the power supplied from the plasma generating unit to generate plasma, _wherein the temperature of the substrate holder is set to 0°C or less, the flow rate _{of the HF} gas is greater than the flow rate of the _CxHyFz gas, and the flow rate of the HF gas is greater than the flow rate of the _CxHyFz gas _. F _z Gas flow rate.