Etching method, semiconductor device manufacturing method, etching program, and plasma processing apparatus

Abstract

This etching method comprises: a step for providing a substrate that comprises a layer to be etched that includes a silicon-containing layer, and a mask that includes metal having openings defined by side walls on the layer to be etched; a step for providing a processing gas that contains a metal-containing gas; and a step for generating plasma from the processing gas, forming a protective layer that contains metal on the upper part and side walls of the mask, and etching the layer to be etched via the openings.

Description

[Technical Field]

[0001] The present disclosure relates to an etching method, a method for manufacturing a semiconductor device, an etching program, and a plasma processing apparatus. [Background technology]

[0002] When etching insulating films such as oxide films using plasma containing gases such as carbon and fluorine, it has been proposed to form a conductive layer by adding WF6 gas to the etching gas in order to suppress shape abnormalities caused by localized charging during etching. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-50984 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides an etching method, a semiconductor device manufacturing method, an etching program, and a plasma processing apparatus that can improve the selectivity of a metal-containing mask. [Means for solving the problem]

[0005] An etching method according to one aspect of the present disclosure includes providing a substrate including a layer to be etched, the layer including a silicon-containing layer, and a mask including a metal having an opening defined by a sidewall over the layer to be etched; supplying a process gas including a metal-containing gas; and generating a plasma from the process gas to etch the layer to be etched through the opening while forming a metal-containing protective layer on top and on the sidewall of the mask. [Effects of the Invention]

[0006] According to the present disclosure, the selectivity of a metal-containing mask can be improved. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating an example of a plasma processing apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram schematically showing an example of the structure of a substrate to be etched by the plasma processing apparatus according to this embodiment. [Figure 3] FIG. 3 is a diagram schematically showing an example of the progress of etching of a substrate in this embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of the etching process in this embodiment. [Figure 5] FIG. 5 is a diagram showing an example of experimental results in this embodiment and a reference example. [Figure 6] FIG. 6 is a diagram showing an example of the relationship between the flow rate of tungsten hexafluoride gas and the mask selectivity. [Figure 7] FIG. 7 is a diagram showing an example of the relationship between the bias voltage and the mask selectivity. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the disclosed etching method, semiconductor device manufacturing method, etching program, and plasma processing apparatus will be described in detail with reference to the drawings. Note that the disclosed technology is not limited to the following embodiments.

[0009] When a metal-containing mask such as tungsten carbide (WC) is used in etching a dielectric film, the metal-containing mask may be etched, resulting in a decrease in the selectivity (etch rate of the dielectric film / etch rate of the metal-containing mask). As semiconductor processes become increasingly miniaturized, the decrease in the selectivity of the metal-containing mask may become a problem. Therefore, there is a need to improve the selectivity of the metal-containing mask.

[0010] [Configuration of Plasma Processing Apparatus 10] FIG. 1 is a schematic cross-sectional view showing an example of a plasma processing apparatus according to an embodiment of the present disclosure. The plasma processing apparatus 10 shown in FIG. 1 is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 10 includes a chamber 12. The chamber 12 has a substantially cylindrical shape. The chamber 12 provides an internal space as a processing space 12c. The chamber 12 is made of, for example, aluminum. The inner wall surface of the chamber 12 is treated to have plasma resistance. For example, the inner wall surface of the chamber 12 is anodized. The chamber 12 is electrically grounded.

[0011] A passage 12p is formed in the sidewall of the chamber 12. A wafer (substrate) W, which is an example of an object to be processed, passes through the passage 12p when being loaded into the processing space 12c and when being unloaded from the processing space 12c. The passage 12p can be opened and closed by a gate valve 12g.

[0012] A support 13 is provided on the bottom of the chamber 12. The support 13 is made of an insulating material. The support 13 has a generally cylindrical shape. The support 13 extends vertically from the bottom of the chamber 12 within the processing space 12c. The support 13 supports a stage 14. The stage 14 is provided within the processing space 12c. The stage 14 is an example of a mounting table and a substrate support.

[0013] The stage 14 has a lower electrode 18 and an electrostatic chuck 20. The stage 14 may further include an electrode plate 16. The electrode plate 16 is made of a conductor such as aluminum and has a generally disk shape. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is made of a conductor such as aluminum and has a generally disk shape. The lower electrode 18 is electrically connected to the electrode plate 16.

[0014] The electrostatic chuck 20 is provided on the lower electrode 18. A wafer W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a body made of a dielectric material. A film-like electrode is provided within the body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to a DC power supply 22 via a switch. When a voltage from the DC power supply 22 is applied to the electrode of the electrostatic chuck 20, an electrostatic attractive force is generated between the electrostatic chuck 20 and the wafer W. The generated electrostatic attractive force attracts the wafer W to the electrostatic chuck 20, and the wafer W is held by the electrostatic chuck 20.

[0015] A focus ring FR is disposed on the peripheral portion of the lower electrode 18 so as to surround the edge of the wafer W. The focus ring FR is an example of an edge ring and is provided to improve etching uniformity. The focus ring FR may be made of, but is not limited to, silicon, silicon carbide, or quartz.

[0016] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (e.g., a refrigerant) is supplied to the flow path 18f from a chiller unit 26 provided outside the chamber 12 via a pipe 26a. The heat exchange medium supplied to the flow path 18f is returned to the chiller unit 26 via a pipe 26b. In the plasma processing apparatus 10, the temperature of the wafer W placed on the electrostatic chuck 20 is adjusted by heat exchange between the heat exchange medium and the lower electrode 18.

[0017] The plasma processing apparatus 10 is provided with a gas supply line 28. The gas supply line 28 supplies a heat transfer gas, for example, He gas, from a heat transfer gas supply mechanism to between the upper surface of the electrostatic chuck 20 and the back surface of the wafer W.

[0018] The plasma processing apparatus 10 further includes an upper electrode 30. The upper electrode 30 is provided above the stage 14. The upper electrode 30 is supported on the upper part of the chamber 12 via a member 32. The member 32 is made of an insulating material. The upper electrode 30 may include a top plate 34 and a support 36. The bottom surface of the top plate 34 faces the processing space 12c and defines the processing space 12c. The top plate 34 may be made of a low-resistance conductor or semiconductor that generates little Joule heat. The top plate 34 has a plurality of gas discharge holes 34a formed therein. The plurality of gas discharge holes 34a penetrate the top plate 34 in the thickness direction.

[0019] The support 36 detachably supports the top plate 34 and may be made of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support 36. A plurality of gas flow holes 36b extend downward from the gas diffusion chamber 36a, each of which communicates with the plurality of gas discharge holes 34a. A gas inlet 36c is formed in the support 36 to introduce a process gas into the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet 36c. The gas inlet 36c is an example of a gas supply port that supplies gas into the chamber 12.

[0020] A gas source group 40 is connected to the gas supply pipe 38 via a valve group 42 and a flow rate controller group 44. The gas source group 40 includes a plurality of gas sources. The plurality of gas sources include sources of a plurality of gases that constitute a process gas used in an etching process or the like. The valve group 42 includes a plurality of on-off valves. The flow rate controller group 44 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers is a mass flow controller or a pressure-controlled flow rate controller. The plurality of gas sources of the gas source group 40 are connected to the gas supply pipe 38 via the corresponding valves of the valve group 42 and the corresponding flow rate controllers of the flow rate controller group 44.

[0021] In the plasma processing apparatus 10, a shield 46 is detachably provided along the inner wall of the chamber 12. The shield 46 is also provided on the outer periphery of the support portion 13. The shield 46 prevents etching by-products from adhering to the chamber 12. The shield 46 can be formed, for example, by coating an aluminum material with a ceramic such as Y2O3.

[0022] A baffle plate 48 is provided between the support 13 and the side wall of the chamber 12. The baffle plate 48 is made, for example, by coating an aluminum base material with a ceramic such as Y2O3. A plurality of through holes are formed in the baffle plate 48. An exhaust port 12e is provided below the baffle plate 48 and at the bottom of the chamber 12. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 has a pressure control valve and a vacuum pump such as a turbomolecular pump.

[0023] The plasma processing apparatus 10 further includes a first high-frequency power supply 62 and a second high-frequency power supply 64. The first high-frequency power supply 62 is a power supply that generates a first high-frequency power supply for generating plasma. The frequency of the first high-frequency power supply is, for example, within a range of 27 MHz to 100 MHz. The first high-frequency power supply 62 is connected to the lower electrode 18 via a matching box 66 and the electrode plate 16. The matching box 66 has a circuit for matching the output impedance of the first high-frequency power supply 62 with the input impedance on the load side (lower electrode 18 side). The first high-frequency power supply 62 may be connected to the upper electrode 30 via the matching box 66. The first high-frequency power supply 62 is an example of a plasma generation unit.

[0024] The second high frequency power supply 64 is a power supply that generates a second high frequency for attracting ions into the wafer W. The frequency of the second high frequency is lower than the frequency of the first high frequency. The frequency of the second high frequency is, for example, within a range of 400 kHz to 13.56 MHz. The second high frequency power supply 64 is connected to the lower electrode 18 via a matching box 68 and the electrode plate 16. The matching box 68 has a circuit for matching the output impedance of the second high frequency power supply 64 with the input impedance on the load side (lower electrode 18 side).

[0025] The plasma processing apparatus 10 may further include a DC power supply unit 70. The DC power supply unit 70 is connected to the upper electrode 30. The DC power supply unit 70 is capable of generating a negative DC voltage and applying the DC voltage to the upper electrode 30.

[0026] The plasma processing apparatus 10 may further include a control unit 80. The control unit 80 may be a computer including a processor, a memory unit, an input device, a display device, etc. The control unit 80 controls each unit of the plasma processing apparatus 10. The control unit 80 allows an operator to input commands, etc., to manage the plasma processing apparatus 10 using the input device. The control unit 80 also allows the display device to visualize and display the operating status of the plasma processing apparatus 10. Furthermore, the memory unit of the control unit 80 stores a control program and recipe data for controlling various processes performed by the plasma processing apparatus 10 using the processor. The processor of the control unit 80 executes the control program and controls each unit of the plasma processing apparatus 10 according to the recipe data, thereby performing the desired process in the plasma processing apparatus 10.

[0027] For example, the control unit 80 controls each unit of the plasma processing apparatus 10 to perform an etching method described below. In one detailed example, the control unit 80 executes a step of providing a wafer (substrate) W including an etching target layer including a silicon-containing layer and a mask including a metal having an opening defined by a sidewall on the etching target layer. The control unit 80 also executes a step of supplying a processing gas including a metal-containing gas. The control unit 80 also executes a step of generating plasma from the processing gas and etching the etching target layer through the opening while forming a metal-containing protective layer on the top and sidewalls of the mask.

[0028] [Substrate to be processed] Next, a substrate to be etched will be described with reference to FIGS. 2 and 3. FIG. 2 is a diagram schematically illustrating an example of the structure of a substrate to be etched by the plasma processing apparatus according to this embodiment. The wafer W shown in FIG. 2 has a silicon-containing layer 102 and a mask 103 on a silicon substrate 101. Examples of the silicon-containing layer (containing film) 102 include a silicon oxide layer (SiO2), a silicon nitride layer (SiN), and a low-k layer. The silicon-containing layer 102 is an example of a silicon-containing dielectric layer. Examples of the low-k layer include an SiOC layer. The silicon-containing layer 102 may have a stacked structure including a silicon oxide layer and a low-k layer, a silicon oxide layer and a silicon nitride layer, or a silicon nitride layer and a low-k layer. The silicon-containing layer 102 is an example of a layer to be etched.

[0029] The mask 103 is a layer on which a mask pattern having a predetermined pattern of openings, for example, comb-shaped openings defined by sidewalls, is formed. The mask 103 is, for example, a metal-containing mask. Examples of metal-containing masks include tungsten, tungsten carbide (WC), molybdenum, or titanium nitride (TiN). The pitch between the openings of the mask 103 is, for example, about 30 nm, and the line CD (Critical Dimension) is, for example, about 10 nm. The thickness of the mask 103 is, for example, about 20 nm, and the thickness of the silicon-containing layer 102 is, for example, about 200 nm. Note that in this embodiment, the wafer W to be processed is assumed to be a substrate for a logic device. The wafer W to be processed may also be used for purposes other than logic devices, and is applicable to, for example, a substrate for a memory on which a high aspect ratio of 30 or more is formed.

[0030] Furthermore, examples of the metal or metal compound contained in the mask 103 include, in addition to the above-mentioned examples, tungsten (W), tungsten carbide (WCα (α is a real number greater than 0, for example, α=1)), tungsten silicide (WSiβ (β is a real number greater than 0, for example, β=1 or 2)), titanium (Ti), titanium nitride (TiNγ (γ is a real number greater than 0, for example, γ=1)), tantalum nitride (TaNδ (δ is a real number greater than 0, for example, δ=1)), molybdenum carbide (MoεC (ε is a real number greater than 0, for example, ε=1 or 2)), molybdenum nitride ( Examples of the mask 103 include MoζN (ζ is a real number greater than 0, e.g., ζ=1 or 2), molybdenum silicide (MoSiη (η is a real number greater than 0, e.g., η=1 or 2), molybdenum boride (MoBΘ (Θ is a real number greater than 0, e.g., Θ=1, 2, or 3)), molybdenum oxide (MoOι (ι is a real number greater than 0, e.g., ι=1, 2, or 3)), rhenium (Re), rhenium oxide (ReOκ (κ is a real number greater than 0, e.g., κ=1, 2, or 3)), and rhenium nitride (ReNλ (λ is a real number greater than 0, e.g., λ=1 or 2)). The mask 103 may include metal elements such as tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), and rhenium (Re). Additionally, the mask 103 may include boron nitride (BN). The mask 103 may include non-metallic elements such as boron (B), carbon (C), nitrogen (N), oxygen (O), silicon (Si), phosphorus (P), and sulfur (S).

[0031] FIG. 3 is a diagram schematically illustrating an example of the progress of etching of a substrate in this embodiment. In this embodiment, etching of the silicon-containing layer 102 of the wafer W progresses as shown in states 104 to 106 in FIG. 3. State 104 is the state before etching begins. State 105 shows a state in which etching is in progress, in which a tungsten-containing protective layer 107 is formed on the upper (top surface) and sidewalls of the mask 103, and grooves 108 are formed through the openings in the mask 103. At this time, the protective layer 107 is deposited thinly on the sidewalls of the mask 103 and thickly on the upper part of the mask 103. In other words, the thickness of the protective layer 107 formed on the upper part of the mask 103 is greater than the thickness of the protective layer formed on the sidewalls of the mask 103. For example, the thickness of the protective layer 107 on the sidewalls of the mask 103 may be approximately 1 nm, and the film thickness ratio of the upper part to the sidewalls (upper film thickness / sidewall film thickness) may be 2 or more and less than 5. In another example, the ratio of the thickness of the upper portion to the sidewall (thickness of the upper portion / thickness of the sidewall) may be 5 or more. In another example, the ratio of the thickness of the upper portion to the sidewall (thickness of the upper portion / thickness of the sidewall) may be less than 2. The thickness of the protective layer 107 formed on the sidewall of the mask 103 may be formed to decrease from the top of the opening of the mask 103 toward the depth. Depending on the etching process, the thickness of the protective layer 107 formed on the upper portion of the mask 103 may be equal to or less than the thickness of the protective layer formed on the sidewall of the mask 103. State 106 is a state in which etching has progressed further from state 105, and the trench 108 has reached the silicon substrate 101. When etching has progressed to state 106, it is determined that a predetermined shape (in one example, a predetermined aspect ratio) has been obtained, and etching is terminated. Note that FIG. 3 omits the etching status other than the two trenches 108.

[0032] [Etching method] Next, the etching method according to this embodiment will be described with reference to a flowchart shown in FIG.

[0033] In the etching method according to this embodiment, the control unit 80 controls the gate valve 12g to be opened. Then, a wafer W having a silicon-containing layer 102 and a mask 103 formed on the silicon-containing layer 102 is loaded into the chamber 12 and placed on the electrostatic chuck 20 of the stage 14. The wafer W is held on the electrostatic chuck 20 by applying a DC voltage to an attraction electrode (not shown) in the electrostatic chuck 20. The control unit 80 then controls the gate valve 12g to be closed, and controls the exhaust device 50 to exhaust gas from the processing space 12c so that the atmosphere in the processing space 12c reaches a predetermined vacuum level. The control unit 80 also controls a temperature control module (not shown) to adjust the temperature of the wafer W to a predetermined temperature (step S1).

[0034] Next, the control unit 80 controls the supply of the process gas to start (step S2). The control unit 80 controls the supply of a mixed gas of WF, C4F, O, and Ar (hereinafter referred to as WF / C4F / O / Ar gas) to the gas inlet 36c as the process gas containing tungsten. The carbon- and fluorine-containing gas, such as C4F6, may be a gas containing one or more of a fluorocarbon gas and a hydrofluorocarbon gas. That is, the carbon- and fluorine-containing gas is a gas containing CxHyFz (x and z are integers of 1 or greater, and y is an integer of 0 or greater). CxHyFz is a compound having a carbon-fluorine bond, such as C2F4, CF4, C3F4, C3F8, C4F8, C4F6, C5F8, CH2F2, CH2F3, CHF3, or CH3F. The oxygen-containing gas may be CO gas, CO2 gas, or the like. The processing gas does not necessarily contain an oxygen-containing gas such as O. The Ar gas may be replaced with another noble gas, such as Xe gas, or an inert gas such as N gas may be used instead of the noble gas.

[0035] The process gas is not limited to a process gas containing tungsten, but may be a process gas containing other metal-containing gases. Examples of the metal-containing gas include, in addition to the above-mentioned tungsten hexafluoride (WF6) gas, tungsten hexabromide (WBr6) gas, tungsten hexachloride (WCl6) gas, WF5Cl gas, tungsten hexacarbonyl (W(CO)6) gas, titanium tetrachloride (TiCl4) gas, molybdenum pentafluoride (MoF5) gas, vanadium hexafluoride (VF6) gas, platinum hexafluoride (PtF6) gas, hafnium tetrafluoride (HfF4) gas, and niobium pentafluoride (NbF5) gas. The metal-containing gas may also be a metal halide-containing gas. Furthermore, the metal-containing gas may contain metal elements such as tungsten, titanium, molybdenum, vanadium, platinum, hafnium, niobium, tantalum, and rhenium.

[0036] The process gas is supplied to the gas inlet 36c, then supplied to the gas diffusion chamber 36a and diffused therein. After being diffused in the gas diffusion chamber 36a, the process gas is supplied in a shower-like manner through the multiple gas outlet holes 34a into the process space 12c of the chamber 12, and introduced into the process space 12c.

[0037] The control unit 80 controls the first high frequency power supply 62 to supply high frequency power for plasma generation (first high frequency power) to the lower electrode 18. That is, in the processing space 12c, plasma is generated from the processing gas by the high frequency power for plasma generation. Here, the high frequency power for plasma generation is less than 5 kW, i.e., 5.6 W / cm. 2 The following is preferable. The wafer W is plasma-processed by the generated plasma. That is, the control unit 80 controls so that plasma is generated from the processing gas by supplying high-frequency power for plasma generation into the chamber 12, and the silicon-containing layer 102 is etched through the mask 103 (step S3). Note that in this embodiment, although an electric bias voltage (second high-frequency power) is not supplied from the second high-frequency power supply 64, ions in the plasma are attracted toward the wafer W by the high-frequency power for plasma generation supplied to the lower electrode 18, and the etching process progresses.

[0038] The control unit 80 determines whether or not a predetermined shape has been obtained in step S3 based on information acquired from a sensor (not shown) of the plasma processing apparatus 10, the processing time according to the recipe, etc. (step S4). If the control unit 80 determines that the predetermined shape has not been obtained (step S4: No), the control unit 80 returns the process to step S3. On the other hand, if the control unit 80 determines that the predetermined shape has been obtained (step S4: Yes), the control unit 80 ends the process.

[0039] When the process is to be completed, the control unit 80 controls the supply of the process gas to be stopped. The control unit 80 also controls the application of a DC voltage with reversed polarity to the electrostatic chuck 20 to remove electricity, and the wafer W is then peeled off from the electrostatic chuck 20. The control unit 80 controls the gate valve 12g to be opened. The wafer W is then unloaded from the process space 12c of the chamber 12 via the passage 12p.

[0040] The unloaded wafer W is then subjected to other substrate processing equipment, such as removal of the mask 103 and formation of a conductive material that functions as a contact pad. In other words, a semiconductor device is manufactured using the wafer W to which the above-described etching method is applied.

[0041] [Experimental Results] Next, experimental results will be described with reference to FIGS. 5 to 7. FIG. 5 is a diagram showing an example of experimental results for this embodiment and a reference example. FIG. 5 shows experimental results for a reference example in which WF6 is not added to the processing gas, and an example corresponding to this embodiment in which WF6 is added to the processing gas. The following processing conditions were used. In the wafer W, the silicon-containing layer 102 was a silicon oxide layer (SiO2). The mask 103 was made of tungsten carbide (WC).

[0042] <Processing conditions> First high frequency power (40MHz): 300W Second RF power (400kHz): 0W Processing gas Example: C4F6 / O2 / Ar gas Example: WF6 / C4F6 / O2 / Ar gas (WF6 flow rate ratio is 1% or less) Processing time: 30 seconds

[0043] As shown in Figure 5, the remaining amount of mask 103 was 12.5 nm in the reference example and 14.8 nm in the example. The loss (amount of consumption) of mask 103 was 3.9 nm in the reference example and reduced to 1.6 nm in the example. The etching amount was made uniform to achieve approximately the same depth, and was 15.9 nm in the reference example and 15.7 nm in the example. The mask selectivity was 4.1 in the reference example and 9.8 in the example, an improvement of more than two times.

[0044] FIG. 6 shows an example of the relationship between the flow rate of tungsten hexafluoride gas and the mask selectivity. Graph 110 in FIG. 6 illustrates the relationship between the flow rate of WF gas and the mask selectivity in the experimental results of FIG. 5. As shown in graph 110, in the reference example where the WF gas additive flow rate is 0 sccm, the WC mask selectivity is 4.1, and in the example where the WF gas additive flow rate is 5 sccm, the WC mask selectivity is 9.8. That is, adding WF gas to the process gas can improve the selectivity between the tungsten carbide (WC) mask 103, which is a metal-containing mask, and the silicon-containing layer 102, which is a silicon oxide layer. Furthermore, the ratio (flow rate ratio) of the WF gas flow rate to the total flow rate of the process gas is preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less.

[0045] Next, the effect of the electrical bias voltage on the mask selectivity will be described. FIG. 7 is a graph showing an example of the relationship between bias voltage and mask selectivity. Graph 111 in FIG. 7 shows the WC mask selectivity when an electrical bias voltage (referred to as bias voltage in FIG. 7) is not supplied (0 V) and when it is supplied (-500 V) when WF6 gas is added to the processing gas. Graph 111 also shows, for reference, the WC mask selectivity when WF6 gas is not added to the processing gas and a bias voltage is not supplied (0 V). As shown in graph 111, when no bias voltage is supplied (0 W), the WC mask selectivity improves when WF6 gas is added. On the other hand, when a bias voltage is supplied (-500 V), the WC mask selectivity does not improve even when WF6 gas is added. That is, it can be seen that a smaller bias voltage has a greater effect on improving the WC mask selectivity.

[0046] In the etching process, in order to improve the etching rate, an electric bias voltage for attracting ions may be supplied to the lower electrode 18 from the second high frequency power supply 64. In this case, the electric bias voltage is preferably −500 V or more and 0 V or less.

[0047] As shown in the above-described embodiment, when a predetermined amount of WF6 is added to the process gas and a bias voltage is not applied or a low bias voltage is applied, the mask selectivity is improved. Because WF6 has a high affinity between metal elements, it is more likely to deposit on the metal-containing mask than on the silicon-containing layer (e.g., silicon oxide layer, silicon nitride layer, low-k layer, etc.) to be etched. On the other hand, when a bias voltage is not applied or a low bias voltage is applied, the ion energy incident on the substrate is zero or low, suppressing etching of the deposits. The interaction between the addition of WF6 and the control of the bias voltage has the effect of depositing WF6 on the metal-containing mask, thereby improving the mask selectivity. While stronger bonding between metal elements is achieved with a mask containing tungsten, which is the same metal as the tungsten contained in WF6, this effect is also achieved with different metals. In another example, the layer to be etched may be etched through a mask containing a metal other than tungsten using a process gas containing a gas containing tungsten as an additive gas, or through a mask containing tungsten using a process gas containing a gas containing a metal other than tungsten as an additive gas. Furthermore, the layer to be etched may be etched through a mask containing a metal other than tungsten using a process gas containing a gas containing a metal other than tungsten as an additive gas. That is, the metal contained in the mask 103 and the metal contained in the metal-containing gas may be the same metal or different metals. In these cases, the mask selectivity can be similarly improved.

[0048] In the above embodiment, the plasma processing apparatus 10 is a capacitively coupled plasma processing apparatus that supplies high frequency power for plasma generation and a bias voltage to the lower electrode 18. However, the present invention is not limited to this. For example, a capacitively coupled plasma processing apparatus may be used that supplies high frequency power for plasma generation to the upper electrode 30 and a bias voltage to the lower electrode 18.

[0049] As described above, according to this embodiment, the control unit 80 controls each part of the apparatus to execute a process of providing a substrate (wafer W) including an etching target layer including a silicon-containing layer 102 and a metal-containing mask 103 having an opening defined by a sidewall on the etching target layer. The control unit 80 controls each part of the apparatus to execute a process of supplying a process gas including a metal-containing gas. The control unit 80 controls each part of the apparatus to execute a process of generating plasma from the process gas and etching the etching target layer through the opening while forming a metal-containing protective layer on the top and sidewalls of the mask 103. As a result, the selectivity of the metal-containing mask 103 can be improved.

[0050] Furthermore, according to this embodiment, the mask 103 contains at least one metal element selected from the group consisting of tungsten, titanium, tantalum, molybdenum, and rhenium, thereby improving the selectivity of the mask 103 containing a metal.

[0051] Furthermore, according to this embodiment, the mask 103 contains at least one nonmetallic element selected from the group consisting of boron, carbon, nitrogen, oxygen, silicon, phosphorus, and sulfur, thereby improving the selectivity of the mask 103 containing a metal.

[0052] Furthermore, according to this embodiment, the mask 103 contains at least one selected from the group consisting of tungsten, tungsten carbide, tungsten silicide, titanium, titanium nitride, tantalum nitride, molybdenum carbide, molybdenum nitride, molybdenum silicide, molybdenum boride, molybdenum oxide, rhenium, rhenium oxide, and rhenium nitride. As a result, it is possible to improve the selectivity between the mask 103 containing at least one selected from the group consisting of tungsten, tungsten carbide, tungsten silicide, titanium, titanium nitride, tantalum nitride, molybdenum carbide, molybdenum nitride, molybdenum silicide, molybdenum boride, molybdenum oxide, rhenium, rhenium oxide, and rhenium nitride and the silicon-containing layer 102.

[0053] Furthermore, according to this embodiment, the metal-containing gas is a metal halide-containing gas, which improves the selectivity of the mask 103 containing a metal.

[0054] According to this embodiment, the metal-containing gas contains at least one metal element selected from the group consisting of tungsten, titanium, molybdenum, vanadium, platinum, hafnium, niobium, tantalum, and rhenium, thereby improving the selectivity of the metal-containing mask 103.

[0055] According to this embodiment, the metal-containing gas contains at least one gas selected from the group consisting of tungsten hexafluoride (WF6) gas, tungsten hexabromide (WBr6) gas, tungsten hexachloride (WCl6) gas, WF5Cl gas, tungsten hexacarbonyl (W(CO)6) gas, titanium tetrachloride gas, molybdenum pentafluoride gas, vanadium hexafluoride gas, platinum hexafluoride gas, hafnium tetrafluoride gas, and niobium pentafluoride gas. As a result, the selectivity of the metal-containing mask 103 can be improved.

[0056] Furthermore, according to this embodiment, the metal contained in the mask 103 and the metal contained in the metal-containing gas are the same metal, which results in an improved selectivity of the mask 103 containing the metal.

[0057] Furthermore, according to this embodiment, the metal contained in the mask 103 and the metal contained in the metal-containing gas are different metals, and as a result, the selectivity of the mask 103 containing the metal can be improved.

[0058] Furthermore, according to this embodiment, the processing gas contains CxHyFz gas (x and z are integers of 1 or more, and y is an integer of 0 or more), which results in an improved selectivity of the mask 103 containing metal.

[0059] Furthermore, according to this embodiment, the CxHyFz gas contains at least one gas selected from the group consisting of CF4, C3F8, C4F8, C4F6, C5F8, CH2F2, CHF3, and CH3F. As a result, the selectivity of the mask 103 containing a metal can be improved.

[0060] Furthermore, according to this embodiment, the processing gas further contains an oxygen-containing gas, which improves the selectivity of the mask 103 containing a metal.

[0061] Furthermore, according to this embodiment, the control unit 80 supplies an electric bias for attracting ions in the etching process, and the voltage of the electric bias is −500 V or more and 0 V or less. As a result, even in a capacitively coupled plasma processing apparatus that supplies high frequency power for generating plasma to the upper electrode 30, the selectivity of the mask 103 containing a metal can be improved.

[0062] Furthermore, according to this embodiment, no electrical bias is applied to attract ions during the etching process, which improves the selectivity of the mask 103 containing metal.

[0063] Furthermore, according to this embodiment, the generated plasma is a capacitively coupled plasma or an inductively coupled plasma, which improves the selectivity of the mask 103 containing a metal.

[0064] Furthermore, according to this embodiment, the generated plasma is a capacitively coupled plasma, the substrate is supported on a substrate support (stage 14), and high frequency power for plasma generation is supplied to the substrate support. As a result, ions and the like are attracted to the wafer W by the high frequency power for plasma generation supplied to the lower electrode 18 of the stage 14, thereby allowing etching to proceed.

[0065] Furthermore, according to this embodiment, the thickness of the protective layer formed on the top of the mask is made thicker than the thickness of the protective layer formed on the sidewall of the mask, thereby improving the selectivity of the mask containing metal.

[0066] Furthermore, according to this embodiment, the thickness of the protective layer formed on the sidewall of the mask is made thinner from the top of the opening toward the depth direction, thereby improving the selectivity of the mask containing metal.

[0067] Furthermore, according to this embodiment, the substrate is a substrate for logic devices, and as a result, etching suitable for logic devices can be performed.

[0068] Furthermore, according to this embodiment, a method for manufacturing a semiconductor device using the above-described etching method is provided, and as a result, a semiconductor device can be manufactured.

[0069] Furthermore, according to this embodiment, an etching program for causing a plasma processing apparatus to execute the above-described etching method is provided, so that the above-described etching method can be executed in the plasma processing apparatus.

[0070] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and various omissions, substitutions, and modifications may be made to the above-described embodiments without departing from the spirit and scope of the appended claims.

[0071] In the above embodiment, the plasma processing apparatus 10 is described as an example in which a process such as etching is performed on a wafer W using capacitively coupled plasma, but the disclosed technology is not limited to this. As long as the apparatus performs a process on a wafer W using plasma, the plasma source is not limited to capacitively coupled plasma, and any plasma source such as inductively coupled plasma, microwave plasma, or magnetron plasma can be used.

[0072] The following additional notes are provided regarding the above-described embodiments.

[0073] (Appendix 1) An etching method, providing a substrate comprising a layer to be etched comprising a silicon-containing layer and a mask comprising a metal having an opening defined by sidewalls over the layer to be etched; providing a process gas comprising a metal-containing gas; generating a plasma from the processing gas, and etching the etching target layer through the opening while forming a metal-containing protective layer on the top and sidewalls of the mask; Etching method.

[0074] (Supplementary Note 2) The mask contains at least one metal element selected from the group consisting of tungsten, titanium, tantalum, molybdenum, and rhenium. 2. The etching method of claim 1.

[0075] (Supplementary Note 3) The mask contains at least one nonmetallic element selected from the group consisting of boron, carbon, nitrogen, oxygen, silicon, phosphorus, and sulfur. 3. The etching method according to claim 1 or 2.

[0076] (Appendix 4) The mask contains at least one selected from the group consisting of tungsten, tungsten carbide, tungsten silicide, titanium, titanium nitride, tantalum nitride, molybdenum carbide, molybdenum nitride, molybdenum silicide, molybdenum boride, molybdenum oxide, rhenium, rhenium oxide, and rhenium nitride. An etching method according to any one of appendices 1 to 3.

[0077] (Supplementary Note 5) The metal-containing gas is a metal halide-containing gas. An etching method according to any one of appendices 1 to 4.

[0078] (Supplementary Note 6) The metal-containing gas contains at least one metal element selected from the group consisting of tungsten, titanium, molybdenum, vanadium, platinum, hafnium, niobium, tantalum, and rhenium. An etching method according to any one of appendices 1 to 5.

[0079] (Supplementary Note 7) The metal-containing gas contains at least one gas selected from the group consisting of tungsten hexafluoride gas, tungsten hexabromide gas, tungsten hexachloride gas, WF5Cl gas, tungsten hexacarbonyl gas, titanium tetrachloride gas, molybdenum pentafluoride gas, vanadium hexafluoride gas, platinum hexafluoride gas, hafnium tetrafluoride gas, and niobium pentafluoride gas; An etching method according to any one of appendices 1 to 5.

[0080] (Supplementary Note 8) The metal contained in the mask and the metal contained in the metal-containing gas are the same metal. An etching method according to any one of appendices 1 to 7.

[0081] (Supplementary Note 9) The metal contained in the mask and the metal contained in the metal-containing gas are different metals. An etching method according to any one of appendices 1 to 7.

[0082] (Supplementary Note 10) The processing gas includes a CxHyFz gas (x and z are integers of 1 or more, and y is an integer of 0 or more). An etching method according to any one of appendices 1 to 9.

[0083] (Supplementary Note 11) The CxHyFz gas includes at least one gas selected from the group consisting of CF4, C3F8, C4F8, C4F6, C5F8, CH2F2, CHF3, and CH3F; 11. The etching method of claim 10.

[0084] (Supplementary Note 12) The processing gas further contains an oxygen-containing gas. An etching method according to any one of appendices 1 to 11.

[0085] (Supplementary Note 13) In the etching step, an electric bias is supplied to attract ions; The voltage of the electrical bias is between −500 V and 0 V. An etching method according to any one of appendices 1 to 12.

[0086] (Supplementary Note 14) In the etching step, no electrical bias is supplied to attract ions. An etching method according to any one of appendices 1 to 12.

[0087] (Supplementary Note 15) The generated plasma is a capacitively coupled plasma or an inductively coupled plasma. An etching method according to any one of appendices 1 to 14.

[0088] (Supplementary Note 16) The generated plasma is a capacitively coupled plasma, the substrate is supported by a substrate support; High frequency power for generating plasma is supplied to the substrate support. An etching method according to any one of appendices 1 to 15.

[0089] (Supplementary Note 17) The thickness of the protective layer formed on the upper part of the mask is greater than the thickness of the protective layer formed on the sidewall of the mask. An etching method according to any one of appendices 1 to 16.

[0090] (Supplementary Note 18) The thickness of the protective layer formed on the side wall of the mask becomes thinner from the top of the opening toward the depth direction. 18. The etching method of claim 17.

[0091] (Supplementary Note 19) The substrate is a substrate for logic devices. An etching method according to any one of appendices 1 to 18.

[0092] (Appendix 20) A method for manufacturing a semiconductor device, comprising the etching method according to any one of Appendices 1 to 19.

[0093] (Supplementary Note 21) An etching program for causing a plasma processing apparatus to execute the etching method according to any one of Supplementary Notes 1 to 19.

[0094] (Supplementary Note 22) A plasma processing apparatus, a chamber; a substrate support disposed within the chamber; a gas supply port for supplying a gas into the chamber; a plasma generating unit that generates plasma in the chamber; A control unit; Equipped with The control unit providing a substrate to the substrate support, the substrate comprising a layer to be etched comprising a silicon-containing layer and a mask comprising a metal on the layer to be etched; providing a process gas comprising a metal-containing gas; generating a plasma from the processing gas to etch the layer to be etched through the mask and form a metal-containing protective layer on the top and sidewalls of the mask; Plasma processing equipment.

[0095] (Supplementary Note 23) In the step of forming the protective layer, an electric bias is supplied to attract ions; The voltage of the electrical bias is between −500 V and 0 V. 23. The plasma processing apparatus according to claim 22.

[0096] (Supplementary Note 24) In the step of forming the protective layer, no electrical bias is supplied to attract ions. 23. The plasma processing apparatus according to claim 22.

[0097] (Supplementary Note 25) The generated plasma is a capacitively coupled plasma or an inductively coupled plasma. 25. The plasma processing apparatus according to any one of claims 22 to 24.

[0098] (Supplementary Note 26) The generated plasma is a capacitively coupled plasma, the substrate is supported by the substrate support; High frequency power for generating plasma is supplied to the substrate support. 25. The plasma processing apparatus according to any one of claims 22 to 24.

[0099] (Appendix 27) An etching method, providing a substrate comprising a layer to be etched comprising a silicon oxide layer and a tungsten-containing mask over the layer to be etched; providing a process gas comprising a tungsten-containing gas; generating a plasma from the process gas and etching the layer to be etched through the tungsten-containing mask; Etching method.

[0100] (Supplementary Note 28) A plasma processing apparatus, a chamber; a substrate support disposed within the chamber; a plasma generating unit that generates plasma in the chamber; A control unit; Equipped with The control unit providing a substrate to the substrate support, the substrate comprising a layer to be etched, the layer comprising a silicon oxide layer, and a tungsten-containing mask on the layer to be etched; providing a process gas comprising a tungsten-containing gas; generating a plasma from the process gas and etching the layer to be etched through the tungsten-containing mask. Plasma processing equipment. [Explanation of symbols]

[0101] 10. Plasma processing device 12 Chambers 14 Stages 18 Lower electrode 30 Upper electrode 62 First high frequency power supply 64 Second high frequency power supply 80 Control Unit 101 Silicon substrate 102 silicon-containing layer 103 Mask 107 Protective layer W wafer

Claims

1. 1. An etching method comprising: providing a substrate comprising a layer to be etched comprising a silicon-containing layer and a mask comprising a metal having an opening defined by sidewalls over the layer to be etched; providing a process gas comprising a metal-containing gas; generating a plasma from the processing gas and etching the etching target layer through the opening while forming a metal-containing protective layer on an upper portion of the mask and on a sidewall of the mask; the thickness of the protective layer formed on the upper surface of the mask is greater than the thickness of the protective layer formed on the sidewall of the mask; Etching method.

2. An etching method comprising: providing a substrate comprising a layer to be etched comprising a silicon-containing layer and a mask comprising a metal having an opening defined by sidewalls over the layer to be etched; providing a process gas comprising a metal-containing gas; generating a plasma from the processing gas and etching the etching target layer through the opening while forming a metal-containing protective layer on an upper portion of the mask and on a sidewall of the mask; the metal contained in the mask and the metal contained in the metal-containing gas are the same metal; Etching method.

3. the mask contains at least one metal element selected from the group consisting of tungsten, titanium, tantalum, molybdenum, and rhenium; The etching method according to claim 1 or 2.

4. the mask contains at least one non-metallic element selected from the group consisting of boron, carbon, nitrogen, oxygen, silicon, phosphorus, and sulfur; The etching method according to claim 1 or 2.

5. the mask contains at least one selected from the group consisting of tungsten, tungsten carbide, tungsten silicide, titanium, titanium nitride, tantalum nitride, molybdenum carbide, molybdenum nitride, molybdenum silicide, molybdenum boride, molybdenum oxide, rhenium, rhenium oxide, and rhenium nitride; The etching method according to claim 1 or 2.

6. The metal-containing gas is a metal halide-containing gas. The etching method according to claim 1 or 2.

7. The metal-containing gas contains at least one metal element selected from the group consisting of tungsten, titanium, molybdenum, vanadium, platinum, hafnium, niobium, tantalum, and rhenium. The etching method according to claim 1 or 2.

8. The metal-containing gas includes at least one gas selected from the group consisting of tungsten hexafluoride gas, tungsten hexabromide gas, tungsten hexachloride gas, WF5Cl gas, tungsten hexacarbonyl gas, titanium tetrachloride gas, molybdenum pentafluoride gas, vanadium hexafluoride gas, platinum hexafluoride gas, hafnium tetrafluoride gas, and niobium pentafluoride gas, The etching method according to claim 1 or 2.

9. the metal contained in the mask and the metal contained in the metal-containing gas are different metals; The etching method according to claim 1 or 2.

10. The processing gas contains a CxHyFz gas (x and z are integers of 1 or more, and y is an integer of 0 or more). The etching method according to claim 1 or 2.

11. The CxHyFz gas includes at least one gas selected from the group consisting of CF4, C3F8, C4F8, C4F6, C5F8, CH2F2, CHF3, and CH3F; The etching method according to claim 10.

12. The process gas further comprises an oxygen-containing gas. The etching method according to claim 1 or 2.

13. providing an electrical bias for attracting ions during the etching step; The voltage of the electrical bias is −500 V or more and 0 V or less. The etching method according to claim 1 or 2.

14. In the etching step, no electrical bias is supplied to attract ions. The etching method according to claim 1 or 2.

15. The plasma generated is a capacitively coupled plasma or an inductively coupled plasma. The etching method according to claim 1 or 2.

16. the plasma generated is a capacitively coupled plasma; the substrate is supported by a substrate support; High frequency power for generating plasma is supplied to the substrate support. The etching method according to claim 1 or 2.

17. the thickness of the protective layer formed on the sidewall of the mask becomes thinner from the top of the opening in a depth direction; The etching method according to claim 1 or 2.

18. The substrate is a substrate for a logic device. The etching method according to claim 1 or 2.

19. A method for manufacturing a semiconductor device, comprising the etching method according to claim 1 or 2.

20. 3. An etching program for causing a plasma processing apparatus to execute the etching method according to claim 1.

21. A plasma processing apparatus, a chamber; a substrate support disposed within the chamber; a gas supply port for supplying a gas into the chamber; a plasma generating unit that generates plasma in the chamber; A control unit; Equipped with The control unit providing a substrate to the substrate support, the substrate comprising a layer to be etched comprising a silicon-containing layer and a mask comprising a metal on the layer to be etched; providing a process gas comprising a metal-containing gas; generating a plasma from the processing gas to etch the etching target layer through the mask and forming a metal-containing protective layer on the top and sidewalls of the mask; the thickness of the protective layer formed on the upper surface of the mask is greater than the thickness of the protective layer formed on the sidewall of the mask; Plasma processing equipment.

22. A plasma processing apparatus comprising: a chamber; a substrate support disposed within the chamber; a gas supply port for supplying a gas into the chamber; a plasma generating unit that generates plasma in the chamber; A control unit; Equipped with The control unit providing a substrate to the substrate support, the substrate comprising a layer to be etched comprising a silicon-containing layer and a mask comprising a metal on the layer to be etched; providing a process gas comprising a metal-containing gas; generating a plasma from the processing gas to etch the etching target layer through the mask and forming a metal-containing protective layer on the top and sidewalls of the mask; the metal contained in the mask and the metal contained in the metal-containing gas are the same metal; Plasma processing equipment.

23. In the step of forming the protective layer, an electrical bias is provided to attract ions; The voltage of the electrical bias is −500 V or more and 0 V or less.

23. The plasma processing apparatus according to claim 21 or 22.

24. In the step of forming the protective layer, no electrical bias is supplied to attract ions.

23. The plasma processing apparatus according to claim 21 or 22.

25. The plasma generated is a capacitively coupled plasma or an inductively coupled plasma.

23. The plasma processing apparatus according to claim 21 or 22.

26. the plasma generated is a capacitively coupled plasma; the substrate is supported by the substrate support; High frequency power for generating plasma is supplied to the substrate support.

23. The plasma processing apparatus according to claim 21 or 22.

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