Etching method and etching apparatus

Abstract

To adequately form an etching shape of a high aspect ratio in an etching process.SOLUTION: A substrate etching method comprises the steps of: (a) supplying a substrate having a first region having a multilayer film arranged by alternately laminating a silicon oxide film and a silicon nitride film, and a second region having a silicon oxide film of a single layer on a substrate support in a chamber; and (b) etching the substrate by plasma generated from a first process gas containing a hydrofluorocarbon gas. The hydrofluorocarbon gas includes a first hydrofluorocarbon gas having an unsaturated bond and represented by CxHyFz (x is an integer of 2 or larger, and y and z represent an integer of 1 or larger).SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to an etching method and an etching processing apparatus. [Background technology]

[0002] Patent Document 1 discloses a method for etching a first region having a multilayer film formed by alternately providing a silicon oxide film and a silicon nitride film, and a second region having a single layer of a silicon oxide film. According to the etching method described in Patent Document 1, a step of generating plasma of a first process gas containing hydrofluorocarbon and a step of generating plasma of a second process gas containing fluorocarbon are alternately and repeatedly performed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-51750 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technique according to the present disclosure appropriately forms an etched shape with a high aspect ratio. [Means for solving the problem]

[0005] One aspect of the present disclosure is a method for etching a substrate, comprising: (a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which silicon oxide films and silicon nitride films are alternately stacked, and a second region having a single layer of silicon oxide film; and (b) etching the substrate with plasma generated from a first process gas containing a hydrofluorocarbon gas, the hydrofluorocarbon gas being represented by CxHyFz (x is an integer of 2 or more, and y and z are integers of 1 or more) and containing a first hydrofluorocarbon gas having an unsaturated bond. Effect of the Invention

[0006] According to the present disclosure, an etching shape with a high aspect ratio can be appropriately formed. [Brief description of the drawings]

[0007] [Figure 1] 1 is a vertical cross-sectional view illustrating a schematic example of a configuration of a plasma processing system. [Diagram 2] FIG. 2 is an explanatory diagram showing an example of an etching target layer formed on a substrate surface. [Diagram 3] FIG. 2 is a flow diagram showing main steps of a plasma treatment according to one embodiment. [Figure 4] FIG. 2 is an explanatory diagram showing an example of the structural formula of C3H2F4 gas. [Diagram 5] FIG. 13 is an explanatory diagram showing an example of an etching process result according to an embodiment of the present invention. [Figure 6] FIG. 13 is an explanatory diagram showing an example of an etching process result according to an embodiment of the present invention. [Figure 7] FIG. 13 is an explanatory diagram showing an example of an etching process result according to an embodiment of the present invention. [Figure 8] FIG. 13 is an explanatory diagram showing an example of an etching process result according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the manufacturing process of a semiconductor device, an etching process is performed on an etching target layer formed by stacking on the surface of a semiconductor substrate (hereinafter simply referred to as "substrate") using a mask layer on which a pattern is formed as a mask. This etching process is generally performed in a plasma processing apparatus.

[0009] Here, in recent plasma processing apparatuses, a 3D NAND HARC (High Aspect Ratio Contact) process may be performed as the above-mentioned etching process, in which holes are deeply excavated in a substrate formed by stacking. In such a 3D NAND HARC process, it is required to form holes with a high aspect ratio while suppressing shape abnormalities such as bowing.

[0010] However, the higher the aspect ratio of the hole to be formed, the more difficult it is to suppress shape abnormalities. In particular, when the etching rate is increased to improve throughput, bowing of the sidewall of the etched hole is more likely to occur.

[0011] The technology according to the present disclosure has been made in consideration of the above circumstances, and suppresses shape abnormalities such as bowing during etching processing, and appropriately forms an etching shape with a high aspect ratio. Hereinafter, a plasma processing system according to one embodiment and a plasma processing method including an etching method according to this embodiment will be described with reference to the drawings. Note that in this specification and the drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0012] <Plasma processing system> First, a plasma processing system according to an embodiment will be described with reference to Fig. 1, which is a vertical cross-sectional view showing an outline of the configuration of the plasma processing system.

[0013] The plasma processing system includes a capacitively coupled plasma processing device 1 and a control unit 2. The plasma processing device 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing device 1 also includes a substrate support 11 and a gas inlet unit. The substrate support 11 is disposed in the plasma processing chamber 10. The gas inlet unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet unit includes a shower head 13. The shower head 13 is disposed above the substrate support 11. In one embodiment, the shower head 13 constitutes at least a part of the ceiling of the plasma processing chamber 10. Inside the plasma processing chamber 10, a plasma processing space 10s is formed, which is defined by the shower head 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. The sidewall 10a is grounded. The showerhead 13 and the substrate support 11 are electrically isolated from the plasma processing chamber 10.

[0014] The substrate support 11 includes a body member 111 and a ring assembly 112. The upper surface of the body member 111 has a central region 111a (substrate support surface) for supporting a substrate (wafer) W, and an annular region 111b (ring support surface) for supporting the ring assembly 112. The annular region 111b surrounds the central region 111a in a plan view. The ring assembly 112 includes one or more annular members, at least one of which is an edge ring.

[0015] In one embodiment, the body member 111 includes a base 113 and an electrostatic chuck 114. The base 113 includes a conductive member. The conductive member of the base 113 functions as a lower electrode. The electrostatic chuck 114 is disposed on an upper surface of the base 113. The upper surface of the electrostatic chuck 114 has the central region 111a and the annular region 111b described above.

[0016] Although not shown, the substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the ring assembly 112, the electrostatic chuck 114, and the substrate W to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas (backside gas) between the back surface of the substrate W and the upper surface of the electrostatic chuck 114.

[0017] The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes a conductive member. The conductive member of the shower head 13 functions as an upper electrode. In addition to the shower head 13, the gas introduction unit may include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0018] The gas supply 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply 20 is configured to supply at least one process gas from a respective gas source 21 through a respective flow controller 22 to the showerhead 13. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply 20 may include one or more flow modulation devices to modulate or pulse a flow rate of the at least one process gas.

[0019] The power source 30 includes an RF power source 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power source 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to the lower electrode and / or the upper electrode. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power source 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more processing gases in the plasma processing chamber 10. In addition, a bias potential is generated on the substrate W by supplying a bias RF signal to the lower electrode, and ion components in the formed plasma can be attracted to the substrate W.

[0020] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to the lower electrode and / or the upper electrode via at least one impedance matching circuit, and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 13 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to the lower electrode and / or the upper electrode. The second RF generating unit 31b is coupled to the lower electrode via at least one impedance matching circuit, and is configured to generate a bias RF signal (bias RF power). In one embodiment, the bias RF signal has a lower frequency than the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 400 kHz to 13.56 MHz. In one embodiment, the second RF generating unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated bias RF signal or signals are provided to the lower electrode, and in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0021] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the lower electrode. In one embodiment, the first DC signal may be applied to another electrode, such as an electrode in an electrostatic chuck. In one embodiment, the second DC generator 32b is connected to the upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the upper electrode. In various embodiments, at least one of the first and second DC signals may be pulsed. It is noted that the first and second DC generators 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generator 32a may be provided instead of the second RF generator 31b.

[0022] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0023] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various steps described in the present disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various steps described herein. In one embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control operations based on a program stored in the storage unit 2a2. The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0024] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0025] For example, in the present embodiment, the plasma processing system has a capacitively coupled plasma (CCP) type plasma processing apparatus 1, but the configuration of the plasma processing system is not limited to this. For example, the plasma processing system may have a processing apparatus including a plasma generating unit such as an inductively coupled plasma (ICP), an electron-cyclotron-resonance plasma (ECR plasma), a helicon wave plasma (HWP), or a surface wave plasma (SWP). In addition, processing apparatuses including various types of plasma generating units, including an alternating current (AC) plasma generating unit and a direct current (DC) plasma generating unit, may be used.

[0026] <Plasma treatment method> Next, an etching process for the substrate W according to the technique of the present disclosure, which is performed using the plasma processing apparatus 1 configured as above, will be described. Fig. 3 is a flow diagram showing the flow of the etching process for the substrate W according to one embodiment.

[0027] In this embodiment, as shown in FIG. 2(a), an example of etching a substrate W having a base layer G (e.g., a SiN film), an etching target layer E, and an organic or boron-based mask layer M formed on the surface is described. In this embodiment, the etching target layer E includes a first region R1 having a multilayer film ON in which silicon oxide films SiO and silicon nitride films SiN are alternately stacked, and a second region R2 having a single layer of silicon oxide film SiO. As the organic mask layer M, for example, a film containing spin-on carbon, tungsten carbide, or amorphous carbon can be used. As the boron-based mask layer M, for example, a film containing boron nitride or boron carbide can be used.

[0028] In this embodiment, as shown in FIG. 2(b), a case will be described as an example in which an etching hole H with a high aspect ratio is formed in an etching target layer E by plasma processing.

[0029] In step S1, the substrate W is carried into the plasma processing chamber 10, and the substrate W is placed on the substrate support 11. Thereafter, a DC voltage is supplied to the lower electrode of the substrate support 11, whereby the substrate W is attracted and held by the electrostatic chuck 114 by Coulomb force (step S1 in FIG. 3: providing the substrate W).

[0030] When the substrate W is held by the electrostatic chuck 114, the inside of the plasma processing chamber 10 is sealed, and the inside of the plasma processing chamber 10 is depressurized to a desired vacuum level by the exhaust system 40. Then, a sequence including an etching process using a first processing gas (step S2 in FIG. 3: first etching process) and an etching process using a second processing gas (step S3 in FIG. 3: second etching process) described below is performed multiple times. In other words, steps S2 and S3 are alternately and repeatedly performed. In these etching processes, the etching target layer E is etched as shown in FIG. 2(b), and a mask pattern (etching hole H) is formed on the substrate W.

[0031] In step S2, first, a first process gas containing a hydrofluorocarbon gas is supplied from the gas supply unit 20 to the plasma processing space 10s via the shower head 13. The hydrofluorocarbon gas in step S2 is represented by CxHyFz (x represents an integer of 2 or more, and y and z represent integers of 1 or more), and contains a first hydrofluorocarbon gas having an unsaturated bond (e.g., a double bond of C). The first hydrofluorocarbon gas also contains a fluorine substituent, for example, a trifluoromethyl group (-CF3). An example of the first hydrofluorocarbon gas is C3H2F4 gas (see the structural formula in FIG. 4). In step S2, the first RF generator 31a supplies high frequency power HF for plasma generation to the upper electrode or the lower electrode to excite the processing gas and generate plasma. Furthermore, the second RF generator 31b supplies high frequency power LF for bias to the lower electrode to control the incidence of ions on the substrate W. Then, the etching target layer E (the first region R1 and the second region R2) formed on the substrate W is etched by the action of the generated plasma.

[0032] In addition, the first processing gas may contain, in addition to the first hydrofluorocarbon gas, a second hydrofluorocarbon gas different from the first hydrofluorocarbon gas. The second hydrofluorocarbon gas may be a hydrofluorocarbon gas having no unsaturated bond. The second hydrofluorocarbon gas may be a hydrofluorocarbon gas having a smaller molecular weight than the first hydrofluorocarbon gas. The second hydrofluorocarbon gas may be, for example, at least one selected from the group consisting of CH2F2 gas and CHF3 gas. When the first processing gas contains the second hydrofluorocarbon gas, the flow rate ratio of the first hydrofluorocarbon gas to the second hydrofluorocarbon gas may be 0.3 or more and 0.5 or less.

[0033] The first process gas may further include at least one fluorocarbon gas selected from the group consisting of C4F6 gas, CF4 gas, C4F8 gas, and C3F8 gas. The first process gas may further include at least one gas selected from the group consisting of CO gas, COS gas, O2 gas, NF3 gas, and SF6 gas. The first process gas may further include an inert gas (e.g., a rare gas such as Ar or N2 gas).

[0034] In step S2, the bias high frequency power LF may be, for example, 20 kW or more. By setting the bias high frequency power LF to 20 kW or more, the amount of ions reaching the bottom of the etching hole H having a high aspect ratio can be increased, and etching at the bottom of the etching hole H can be promoted.

[0035] In step S2, both the high frequency power HF for plasma generation and the high frequency power LF for bias may be supplied periodically. The period during which the high frequency power HF for plasma generation is supplied to the upper electrode or the lower electrode may be synchronized with the period during which the high frequency power LF for bias is supplied to the lower electrode. The frequency that defines the period during which the high frequency power HF for plasma generation is supplied may be, for example, 2 kHz or more and 10 kHz or less, or 2 kHz or more and 5 kHz or less. In this case, the duty ratio indicating the proportion of the time during which the high frequency power HF for plasma generation is supplied to the upper electrode in one period may be, for example, 20% or more and 60% or less, or 30% or more and 50% or less. By controlling the frequency and duty ratio of the high frequency power HF for plasma generation within the above range, dissociation of the plasma can be suppressed and the amount of polymer radicals generated can be increased. As a result, the amount of polymer as a protective film that adheres to the side wall of the etching hole H can be increased.

[0036] In addition, the plasma generated from the first hydrofluorocarbon gas contained in the first process gas used in step S2 has a higher etching rate for the silicon nitride film SiN than for the silicon oxide film SiO. That is, in step S2, the etching rate of the first region R1 is higher than the etching rate of the second region R2. Therefore, in step S2, the first region R1 is preferentially etched over the second region R2. Therefore, when there is a large difference between the depth of the etching hole H formed in the first region R1 and the depth of the etching hole H formed in the second region R2, step S3 described below may be performed.

[0037] In step S3, first, a second process gas containing at least one fluorocarbon gas selected from the group consisting of C4F6 gas, CF4 gas, C4F8 gas, and C3F8 gas is supplied from the gas supply unit 20 to the plasma processing space 10s via the shower head 13. The second process gas may not contain the first hydrofluorocarbon gas, or may contain the first hydrofluorocarbon gas at a flow rate ratio different from the flow rate ratio of the first hydrofluorocarbon gas to the total flow rate of the first process gas. In one example, the second process gas contains the first hydrofluorocarbon gas at a flow rate ratio lower than the flow rate ratio of the first hydrofluorocarbon gas to the total flow rate of the first process gas. In step S3, the first RF generator 31a supplies high frequency power HF for plasma generation to the upper electrode or the lower electrode to excite the second process gas and generate plasma. Furthermore, the second RF generator 31b supplies high frequency power LF for bias to the lower electrode to control the incidence of ions on the substrate W. Then, the etching target layer E (the first region R1 and the second region R2) formed on the substrate W is etched by the action of the generated plasma.

[0038] The second process gas may include a third hydrofluorocarbon gas different from the first hydrofluorocarbon gas, or the third hydrofluorocarbon gas may be the same gas as the second hydrofluorocarbon gas.

[0039] The second process gas may further include at least one selected from the group consisting of CO gas, COS gas, O2 gas, NF3 gas, and SF6 gas, and may further include an inert gas (e.g., a rare gas such as Ar or N2 gas).

[0040] In step S3, the high frequency power LF for bias may be 20 kW or more. The high frequency power HF for plasma generation and the high frequency power LF for bias may both be supplied periodically, and the periods during which the high frequency power HF for plasma generation and the high frequency power LF for bias are supplied may be synchronized. The frequency that defines the period during which the high frequency power HF for plasma generation is supplied may be, for example, 2 kHz or more and 10 kHz or less, or 2 kHz or more and 5 kHz or less. In this case, the duty ratio of the high frequency power HF for plasma generation may be, for example, 20% or more and 60% or less, or 30% or more and 50% or less.

[0041] The plasma generated from the fluorocarbon gas contained in the second process gas used in step S3 has a higher etching rate for the silicon oxide film SiO than for the silicon nitride film SiN. That is, in step S3, the etching rate of the second region R2 is higher than that of the first region R1. Therefore, in step S3, the second region R2 is preferentially etched over the first region R1. Therefore, when the difference between the depth of the etching hole H formed in the first region R1 and the depth of the etching hole H formed in the second region R2 in step S2 is large, the difference can be reduced by performing step S3.

[0042] In this embodiment, the sequence including step S2 and step S3 may be alternately and repeatedly executed, which further suppresses the occurrence of a difference between the depth of the etching hole H formed in the first region R1 and the depth of the etching hole H formed in the second region R2. In addition, the ratio of the processing time of step S2 and step S3 executed in this sequence can be determined arbitrarily. In one example, from the viewpoint of appropriately forming the etching holes H in both the first region R1 and the second region R2, the ratio of the processing time of step S2 (first etching process) to the processing time of step S3 (second etching process) may be set to 2 or more and 3 or less.

[0043] When the formation of the mask pattern (etching holes H) on the etching target layer E of the substrate W is completed, the etching process in the plasma processing apparatus 1 is terminated (Step S4 in FIG. 3: Stop the etching process).

[0044] The substrate W that has been subjected to the etching process is then carried out of the plasma processing chamber 10 by a substrate transport mechanism (not shown) (Step S5 in FIG. 3: carrying out the substrate W), and a series of plasma processing steps for the substrate W is completed.

[0045] <Effects of the technology disclosed herein> Fig. 5 is an explanatory diagram showing an example of the tendency of the etching process result according to the embodiment. Fig. 5(a) shows the amount of polymer P formed on the side wall of the etching hole H when only CH2F2 gas was supplied (Reference Example 1), Fig. 5(b) shows the amount of polymer P formed on the side wall of the etching hole H when a mixture of CH2F2 gas and C3H2F4 gas was supplied (Example 1), and Fig. 5(c) shows the amount of polymer P formed when only C3H2F4 gas was supplied (Example 2). In Figs. 5(b) and (c), the amount of polymer formed is shown as a ratio when the amount of polymer formed in Reference Example 1 is set as a reference value of "1". 6 is an explanatory diagram showing an example of the tendency of the etching process result according to the embodiment. Fig. 6(a) shows the tendency of the CD value of the etching hole H when only CH2F2 gas is supplied (Reference Example 2). Fig. 6(b) shows the tendency of the CD value of the etching hole H when a mixture of CH2F2 gas and C3H2F4 gas is supplied (Example 3).

[0046] 5, it can be seen that as the flow rate ratio of C3H2F4 gas to CH2F2 gas increases during the etching process, the formation position of the polymer P changes relative to the sidewall of the etching hole H. Specifically, it can be seen that as the flow rate ratio of the supplied C3H2F4 gas increases, the formation position of the polymer P transitions from the top side (shoulder) of the etching hole H to the bottom side (Btm side).

[0047] 6, it is understood that the formation of bowing in the etching hole H is suppressed by supplying C3H2F4 gas to the plasma processing space 10s in addition to CH2F2 gas in the etching process. Specifically, it is understood that the BowCD value (CD value at the middle of the etching hole H) in Example 3 is smaller than the BowCD value in Reference Example 2. It is also understood that the BtmCD value (CD value at the bottom of the etching hole H) is larger than the BtmCD value in Reference Example 2. In other words, it is understood that the difference between the TopCD value (CD value at the top of the etching hole H), the BowCD value, and the BtmCD value is small, and bowing is suppressed, and an etching hole H with a high aspect ratio is appropriately formed.

[0048] In this manner, by using C3H2F4 gas as the etching gas in the etching process, the position at which the polymer, which is the reaction product, is formed can be shifted to the bottom side of the etching hole H, thereby improving the bowing that occurs in the etching hole H. This is believed to be due to the fact that the reactivity of C3H2F4 gas is smaller than that of CH2F2 gas. Specifically, the polymer formation position shifts from the upper side of the etching hole H to the side wall surface where bowing occurs, thereby protecting the side wall surface of the etching hole H and suppressing the occurrence of bowing. Also, the amount of ions that reach the bottom of the etching hole H with a high aspect ratio increases, promoting etching at the bottom of the etching hole H.

[0049] In this embodiment, as described above, the high frequency power LF for bias is supplied to the lower electrode in the form of a pulse wave of, for example, 20 kW or more. As a result, during the ON time of the high frequency power LF, ions can be attracted to the etching hole H to proceed with etching, and during the OFF time, polymer can be uniformly and firmly formed as a protective film on the side wall of the etching hole H without attracting ions to the etching hole H. In other words, the polymer formed during the OFF time can protect the side wall of the etching hole H during the ON time, thereby suppressing the occurrence of bowing.

[0050] Next, Fig. 7 is an explanatory diagram showing an example of the tendency of the etching process result according to the embodiment. Fig. 7(a) shows the depth (etching rate) of the etching hole H when only CH2F2 gas was supplied (Reference Example 3), and Fig. 7(b) shows the depth (etching rate) when a mixture of CH2F2 gas and C3H2F4 gas was supplied (Example 4). Note that Fig. 7(b) shows the depth of the etching hole H as a ratio when the depth of the etching hole H in Reference Example 3 is set as a reference value of "1". In Example 4, in order to properly compare the etching rate with Reference Example 3, the plasma treatment was performed under the same treatment conditions (treatment time, treatment pressure, treatment temperature, etc.) as those in Reference Example 3, and the neck CD value was adjusted to be uniform by adjusting the O gas ratio in the treatment gas.

[0051] 7, it can be seen that the formation speed of the etching hole H, that is, the etching rate (amount of etching per time) increases by supplying C3H2F4 gas in addition to CH2F2 gas to the plasma processing space 10s in the etching process. Specifically, the inventors of the present invention have found that by mixing C3H2F4 gas as the etching gas with the processing gas, the etching rate can be improved by 5% or more (6% in the illustrated example) compared to (a) Reference Example 3. This is believed to be due to the fact that, as described above, the amount of ions reaching the bottom of the high aspect ratio etching hole H increases, thereby accelerating etching at the bottom of the etching hole H.

[0052] 8 is a graph showing the etching rate (horizontal axis) of the etching target layer E and the etching rate (vertical axis) of the silicon-based chamber internal member when the first processing gas containing C3H2F4 gas is used. In FIG. 8, the solid line shows the etching rate of the etching target layer E and the silicon-based chamber internal member when the first processing gas is used (Example 5), and the dashed line shows the etching rate of the etching target layer E and the silicon-based chamber internal member when the first processing gas is not used (Reference Example 4).

[0053] During the etching process of the etching target layer E (steps S2 and S3 in FIG. 3), silicon-based members (e.g., the shower head 13, the ring assembly 112, etc.) disposed inside the plasma processing chamber 10 are etched and consumed at the same time as the etching target layer E is etched. When the silicon-based chamber internal members are consumed in this manner, the plasma generation environment inside the plasma processing chamber 10 changes, and it may become difficult to obtain uniform etching process results for the substrate W.

[0054] In this regard, in the etching process according to the present embodiment, the first process gas containing C3H2F4 gas as the first hydrofluorocarbon gas is used to perform the etching process of the substrate W, thereby reducing wear of the silicon-based internal chamber members. Specifically, as shown in Fig. 8, it was found that by mixing C3H2F4 gas as the etching gas into the process gas, the etching rate can be improved (improved by 5% or more as shown in Fig. 7) compared to Reference Example 4, while reducing wear (etching rate) of the silicon-based internal chamber members by about 50%. This is believed to be because, as described above, C3H2F4 gas contains a fluorine substituent (a trifluoromethyl group in the embodiment), which improves the etching rate, and also contains an unsaturated bond (a double bond of C in the embodiment), which allows a polymer to be formed as a protective film on the surface of silicon-based chamber internal components.

[0055] 5 to 7, the use of C3H2F4 gas as the etching gas in the etching process suppresses the occurrence of bowing on the sidewall of the etching hole H. In addition, the etching rate in the etching process can be improved.

[0056] Furthermore, according to this embodiment, as described above, by alternately repeating a plasma treatment (step S2) using a first processing gas containing a first hydrofluorocarbon gas and a plasma treatment (step S3) using a second processing gas containing a fluorocarbon gas, etching holes H can be appropriately formed in both the first region R1 and the second region R2 as the etching target layer E.

[0057] Moreover, according to this embodiment, as can be seen from the results shown in FIG. 8, by using C3H2F4 gas as the etching gas in the etching process, the etching rate can be improved while reducing wear on silicon-based internal chamber members.

[0058] According to the above embodiment, in the etching process, the first hydrofluorocarbon gas and the second hydrofluorocarbon gas are used in combination, and the flow rates of the hydrofluorocarbon gases are controlled, so that the position at which the polymer is formed relative to the etching hole H can be appropriately adjusted.

[0059] In the above embodiment, the etching target layer E includes the first region R1 having a multilayer film ON in which silicon oxide films SiO and silicon nitride films SiN are alternately stacked, and the second region R2 having a single layer of silicon oxide film SiO, but the type of the etching target layer E formed on the substrate W is not limited to this. Specifically, even if only the first region R1 (a multilayer film ON in which silicon oxide films SiO and silicon nitride films SiN are alternately stacked) is formed as the etching target layer on the surface of the substrate W, the plasma processing according to the above embodiment can be performed.

[0060] In the above embodiment, steps S2 and S3 are alternately repeated to uniformly control the depth of the etching hole H formed in the first region R1 and the second region R2, but when only the first region R1 is formed as the etching target layer, step S3 in which the second region is preferentially etched may be omitted as appropriate. When only the first region R1 is formed as above, the ratio of the processing times of steps S2 and S3 may be changed as appropriate so that the processing time of step S2 is longer than that of step S3.

[0061] In the above embodiment, an example has been described in which an etching hole H is formed as a mask pattern in the etching target layer E. However, the patterning shape formed in the etching target layer E is not limited to a hole shape and may be, for example, a trench shape.

[0062] In the above embodiment, the unsaturated bond contained in the first hydrofluorocarbon gas is a double bond of C, and the fluorine substituent is a trifluoromethyl group (-CF3), but the structure of the first hydrofluorocarbon gas is not limited to this. That is, for example, the unsaturated bond contained in the first hydrofluorocarbon gas may be a triple bond of C, and the fluorine substituent may be any fluoromethyl group (-CFx). In addition, for example, the number of unsaturated bonds and fluoromethyl groups contained in the first hydrofluorocarbon gas is not limited to one.

[0063] The embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0064] 1. Plasma processing equipment 10 Plasma Processing Chamber 10s Plasma treatment space 11 Substrate support 31 RF power supply ON multilayer film SiO Silicon oxide film R1 1st area R2 2nd area SiN Silicon nitride film W substrate

Claims

1. (a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which silicon oxide films and silicon nitride films are alternately stacked, and a second region having a single layer of silicon oxide film; (b) etching the substrate with a plasma generated from a first process gas comprising a hydrofluorocarbon gas; Equipped with The hydrofluorocarbon gas is ｘ H ｙ F ｚ (x represents an integer of 2 or more, y and z represent integers of 1 or more), comprising a first hydrofluorocarbon gas having an unsaturated bond and a second hydrofluorocarbon gas different from the first hydrofluorocarbon gas; The flow rate ratio of the first hydrofluorocarbon gas to the second hydrofluorocarbon gas is 0.3 or more and 0.5 or less. Etching method.

2. The etching method according to claim 1 , wherein the second hydrofluorocarbon gas has no unsaturated bonds.

3. 3. The etching method according to claim 1, wherein the second hydrofluorocarbon gas has a smaller molecular weight than the first hydrofluorocarbon gas.

4. The second hydrofluorocarbon gas is CH ２ F ２ and CHF ３ The etching method according to any one of claims 1 to 3, wherein the etching gas is at least one selected from the group consisting of:

5. (a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which silicon oxide films and silicon nitride films are alternately stacked, and a second region having a single layer of silicon oxide film; (b) etching the substrate with a plasma generated from a first process gas comprising a hydrofluorocarbon gas; (c) etching the substrate with a plasma generated from a second process gas comprising a fluorocarbon gas; Equipped with The hydrofluorocarbon gas is ｘ H ｙ F ｚ (x represents an integer of 2 or more, and y and z represent integers of 1 or more), and includes a first hydrofluorocarbon gas having an unsaturated bond, (b) and (c) are alternately repeated; a ratio of the processing time in (b) to the processing time in (c) is 2 or more and 3 or less; Etching method.

6. (a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which silicon oxide films and silicon nitride films are alternately stacked, and a second region having a single layer of silicon oxide film; (b) etching the substrate with a plasma generated from a first process gas comprising a hydrofluorocarbon gas; (c) etching the substrate with a plasma generated from a second process gas comprising a fluorocarbon gas; Equipped with The hydrofluorocarbon gas is ｘ H ｙ F ｚ (x represents an integer of 2 or more, and y and z represent integers of 1 or more), and includes a first hydrofluorocarbon gas having an unsaturated bond, a ratio of the processing time in (b) to the processing time in (c) is 2 or more and 3 or less; Etching method.

7. 7. The etching method according to claim 5, wherein the second process gas does not contain the first hydrofluorocarbon gas, or contains the first hydrofluorocarbon gas at a flow rate ratio different from a flow rate ratio of the first hydrofluorocarbon gas to a total flow rate of the first process gas.

8. 8. The etching method according to claim 5, wherein the second process gas contains a third hydrofluorocarbon gas different from the first hydrofluorocarbon gas.

9. 9. The etching method according to claim 8, wherein the third hydrofluorocarbon gas has no unsaturated bonds and has a smaller molecular weight than the first hydrofluorocarbon gas.

10. 10. The etching method according to claim 1, wherein the first hydrofluorocarbon gas has a trifluoromethyl group (-CF3).

11. The first hydrofluorocarbon gas is ３ H ２ F ４ The etching method according to any one of claims 1 to 10,

12. The etching method according to any one of claims 1 to 11, wherein the first process gas further contains a fluorocarbon gas.

13. The fluorocarbon gas is C ４ F ６ Gas, CF ４ Gas, C. ４ F ８ Gas and C ３ F ８ The etching method according to claim 12, wherein the gas is at least one selected from the group consisting of:

14. The first process gas is a mixture of CO gas, COS gas, and O ２ Gas, NF ３ Gas and SF ６ The etching method according to any one of claims 1 to 13, further comprising at least one selected from the group consisting of gases.

15. 15. The etching method according to claim 1, wherein in (b), a high-frequency bias power of 20 kW or more is supplied to the substrate support.

16. The etching method according to any one of claims 1 to 15, wherein a surface of the substrate has an organic or boron-based mask.

17. a processing chamber; a substrate support disposed within the processing chamber for supporting a substrate; a gas supply unit for supplying a first process gas into the process chamber; a plasma generating unit that generates plasma from the first processing gas; A control unit; Equipped with The control unit controls the gas supply unit and the plasma generation unit, (a) providing the substrate on the substrate support, the substrate including a first region having a multilayer film in which silicon oxide films and silicon nitride films are alternately stacked, and a second region having a single layer of silicon oxide film; (b) etching the substrate with a plasma generated from the first process gas comprising a hydrofluorocarbon gas; Including, The first process gas is ｘ H ｙ F ｚ (x represents an integer of 2 or more, and y and z represent integers of 1 or more), comprising a first hydrofluorocarbon gas having an unsaturated bond and a second hydrofluorocarbon gas different from the first hydrofluorocarbon gas; The flow rate ratio of the first hydrofluorocarbon gas to the second hydrofluorocarbon gas is 0.3 or more and 0.5 or less. An etching processing apparatus configured to perform an etching process.

18. a processing chamber; a substrate support disposed within the processing chamber for supporting a substrate; a gas supply unit for supplying a first process gas into the process chamber; a plasma generating unit that generates plasma from the first processing gas; A control unit; Equipped with The control unit controls the gas supply unit and the plasma generation unit, (a) providing the substrate on the substrate support, the substrate including a first region having a multilayer film in which silicon oxide films and silicon nitride films are alternately stacked, and a second region having a single layer of silicon oxide film; (b) etching the substrate with a plasma generated from the first process gas comprising a hydrofluorocarbon gas; (c) etching the substrate with a plasma generated from a second process gas comprising a fluorocarbon gas; Including, The hydrofluorocarbon gas is ｘ H ｙ F ｚ (x represents an integer of 2 or more, and y and z represent integers of 1 or more), and includes a first hydrofluorocarbon gas having an unsaturated bond, (b) and (c) are alternately repeated; a ratio of the processing time in (b) to the processing time in (c) is 2 or more and 3 or less; An etching processing apparatus configured to perform an etching process.

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