Method for etching silicon-containing film and method for manufacturing semiconductor device including same

Abstract

The present invention relates to a method for etching a silicon-containing film, and more particularly, to a method for etching a silicon-containing film using a nitrosyl fluoride (FNO)-containing etching gas and a method for manufacturing a semiconductor device including the same.

Description

Technical Field

[0001] The present invention relates to a method for etching a silicon-containing film, and more particularly, to a method for etching a silicon-containing film using an etching gas containing nitrosyl fluoride (FNO) and a method for manufacturing a semiconductor device comprising the same. Background Art

[0002] Generally, a series of processes such as deposition, etching, ion implantation, and cleaning are performed to manufacture semiconductor devices. These processes are performed in a process chamber that can maintain the process conditions under various conditions such as atmospheric pressure, low pressure, and vacuum. Among them, the etching process is a process that selectively removes a portion of a thin film formed on a substrate through a deposition process to form an ultrafine structure (pattern, etc.) of a desired shape.

[0003] Etching processes, especially dry etching processes, are performed by injecting a gaseous etching gas and reacting the injected etching gas with an etching object (e.g., a silicon-containing film) on a substrate to form volatile byproducts, thereby removing part or all of the thin film. As a method of dry etching process, a plasma etching method is mainly used, which utilizes active ions, or generally utilizes plasma to increase the reactivity between the etching gas and the etching object. The plasma etching method is a method of converting an etching gas into a plasma to form highly reactive free radicals and ions, so that these free radicals (Radicals) and ions (Ions) physically or chemically etch the etching object.

[0004] The methods of dry etching process include plasma etching methods, such as capacitively coupled plasma (CCP), inductively coupled plasma (ICP), remote plasma system (RPS), electron cyclotron resonance (ECR) plasma, transformer coupled plasma (TCP), high density plasma (HDP), reactive ion etching (RIE), magnetically enhanced reactive ion etching (MRI), etc.

[0005] Direct plasma technology is mainly used to convert etching gas into plasma. Direct plasma technology is a method of making plasma generated by directly applying power to the process chamber, such as capacitively coupled plasma or inductively coupled plasma, directly contact the substrate and the etching object. In this case, in order to help the etching gas to convert into plasma and accelerate physical etching, helium (He), nitrogen (N 2 ), argon (Ar) and other inert gases.

[0006] In the etching process, in order to form an ultra-fine structure of the desired shape, the etching object to be etched must have a high etching rate (Etch Rate), while the thin film that does not need to be etched requires a low etching rate (Etch Rate). The ratio of the etching rate of the thin film to be etched to the etching rate of the thin film that does not need to be etched is called the selectivity (Selectivity), and the etching process requires a reaction gas with a high selectivity. In particular, in recent years, in order to manufacture semiconductor devices that can be miniaturized or highly integrated, it is necessary to develop a reaction gas with a higher selectivity.

[0007] In the past, carbon tetrafluoride (CF 4 ), hexafluoropropylene (C 3 F 6 ), sulfur hexafluoride (SF 6 ), nitrogen trifluoride (NF 3 ) and other perfluorinated compound gases. However, it is difficult to treat the waste gas discharged after the etching process with the previous perfluorinated compound reaction gas, so a lot of processing costs are required before it is discharged into the atmosphere. In addition, the previous perfluorinated compound gas has a long atmospheric lifetime and a very high global warming potential (GWP), so it is pointed out to be a major factor causing climate change.

[0008] Thus, there is a need for an alternative reactive gas having low global warming potential and excellent etching performance for silicon-containing films, particularly having excellent selectivity. Summary of the invention

[0009] Problems to be solved by the invention

[0010] The present invention aims to solve the problems of the prior art and aims to provide a method for etching a silicon-containing film as follows: as a dry etching method, an environmentally friendly etching gas with low global warming potential is used to replace the previous reaction gas containing perfluorinated compound gas.

[0011] Another object of the present invention is to provide a method capable of etching a silicon-containing film with a high selectivity by activating an etching gas containing an inert gas (argon gas or the like) that assists in generating plasma and performs physical etching.

[0012] Furthermore, an object of the present invention is to provide a method for manufacturing a semiconductor device, which includes the above-mentioned method for etching a silicon-containing film.

[0013] The purpose of the present invention is not limited to the above purpose, and other purposes and advantages not mentioned in the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Moreover, it is obvious that the purposes and advantages of the present invention can be achieved by the means and combinations thereof indicated in the scope of the invention claims.

[0014] Solutions for solving problems

[0015] In order to achieve the above-mentioned purpose, according to one embodiment of the present invention, a method for etching a silicon-containing film can be provided, which includes the following steps: introducing a substrate including a first silicon-containing film and a second silicon-containing film into a process chamber of an etching device; supplying an etching gas containing a reaction gas and an inactive gas into the above-mentioned process chamber; forming free radicals of the etching gas in the above-mentioned process chamber which maintains a specified pressure; and etching the above-mentioned first silicon-containing film on the above-mentioned substrate using the free radicals (radical) of the above-mentioned etching gas, the above-mentioned reaction gas containing nitrosyl fluoride (FNO) gas, and the above-mentioned specified pressure is set so that the sign of the slope of the etching rate of the above-mentioned first silicon-containing film with respect to the pressure is different from the sign of the slope of the etching rate of the above-mentioned second silicon-containing film with respect to the pressure.

[0016] The first silicon-containing film and the second silicon-containing film may be different from each other, and may be independently selected from one of a silicon oxide film, a silicon nitride film, a polysilicon film, and a silicide film.

[0017] The first silicon-containing film may include a silicon nitride film, and the second silicon-containing film may include a silicon oxide film.

[0018] The content of the reaction gas may be greater than 20 vol % based on the total content of the reaction gas and the inert gas being 100 vol %.

[0019] The inert gas may include argon (Ar), nitrogen (N 2 ) and helium (He).

[0020] The prescribed pressure may be adjusted within a range of 100 mTorr to 1 Torr. According to one example, the prescribed pressure may be adjusted within a range of 350 mTorr to 500 mTor.

[0021] The step of forming radicals of the etching gas may include a plasma etching method.

[0022] The above-mentioned plasma etching method can be one of capacitively coupled plasma (CCP), inductively coupled plasma (ICP), remote plasma system (RPS), electron cyclotron resonance (ECR) plasma, transformer coupled plasma (TCP), high density plasma (HDP), reactive ion etching (RIE) and magnetically enhanced reactive ion etching (RIE).

[0023] According to another embodiment of the present invention, there may be provided a method for manufacturing a semiconductor device including the method for etching a silicon-containing film according to an embodiment of the present invention.

[0024] Effects of the Invention

[0025] According to the present invention, an etching gas containing nitrosyl fluoride (FNO) has a low global warming potential (GWP), and thus has an effect of being able to etch a silicon-containing film with a high selectivity while being environmentally friendly.

[0026] Hereinafter, the above-mentioned effects and the effects of the present invention will be described together with specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. 4 is a schematic diagram of an etching apparatus including a process chamber for performing an etching method according to an embodiment of the present invention.

[0028] Figure 2 The figure is a flow chart of an etching method for a silicon-containing film according to an embodiment of the present invention.

[0029] Figure 3 FIG. 4 is a graph showing the etching rate of silicon nitride film as a function of etching gas ratio, pressure and applied power.

[0030] Figure 4 FIG. 4 is a graph showing the etching rate of silicon oxide film as a function of etching gas ratio, pressure and applied power.

[0031] Figure 5 FIG. 4 is a graph showing the selectivity of silicon nitride film and silicon oxide film as a function of etching gas ratio, pressure and applied power. DETAILED DESCRIPTION

[0032] Hereinafter, the above-mentioned objects, features and advantages will be described in detail with reference to this specification, so that those skilled in the art can easily implement the technical ideas of the present invention. In the process of describing the present invention, when it is judged that the specific description of the known technology related to the present invention may unnecessarily confuse the main idea of ​​the present invention, the detailed description will be omitted.

[0033] In the process of describing the present invention, when it is judged that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0034] In this specification, when “including”, “having”, “composed of”, “configured”, “having”, etc. are used to describe structural elements, other structural elements may be added unless “only” is used. When structural elements are expressed in the singular, the plural is included unless otherwise clearly stated.

[0035] When interpreting the structural elements of the present specification, they should be interpreted as including a range of error even if there is no separate explicit description.

[0036] Hereinafter, the present invention will be described in more detail.

[0037] Figure 1 As an example of an etching device including a process chamber for performing an etching method according to an embodiment of the present invention, a schematic diagram of an etching device using capacitively coupled plasma is provided. The etching device is configured to generate plasma P by applying a specified power while maintaining a specified pressure condition, and includes a process chamber 10, a substrate support 20, a nozzle 30, an impedance matching network 40, a radio frequency (RF) power supply 50, a gas supply unit, etc. The substrate S includes a silicon semiconductor substrate containing a silicon film. The etching device 1 can be configured to easily generate plasma P near the surface of the substrate S, or can be configured to easily undergo a chemical reaction. The process chamber 10 is configured to maintain a specified pressure condition during the process, and can also include a substrate insertion device (not shown) for inserting a substrate before and after the process. In addition, a vacuum system (not shown) including a vacuum pump can be connected to enable the process chamber 10 to reach and maintain a specific pressure condition.

[0038] In order to perform the process, the substrate S is placed, and the substrate support 20 is configured to generate direct plasma. In this case, the substrate support 20 includes a discharge electrode 210, and the discharge electrode 210 is used to apply power to the etching gas in the process chamber to generate direct plasma. Figure 1Although not shown in FIG. 1 , the substrate support 20 may include a heater and a cooling water flow path for controlling the temperature of the substrate S during the process. Figure 1 As shown in FIG. 1 , the substrate support 20 may include a substrate fixing unit such as an electrostatic chuck to fix the substrate S during the process.

[0039] The etching gas including the reactive gas and the inactive gas can be supplied to the shower head 30 at a constant flow rate through the gas supply unit and injected into the process chamber 10. In this case, the gas supply unit may include a gas supply system, and the gas supply system may include a mass flow controller (MFC) to maintain a constant flow rate of the etching gas. Figure 1 However, a radio frequency power source and an impedance matching system for generating direct plasma may be additionally connected to the showerhead 30 .

[0040] The process chamber in the etching device is equipped with a radio frequency power supply 50 and an impedance matching network 40 connected to the discharge electrode 210 to generate direct plasma. The radio frequency power supply and the impedance matching network form direct plasma by transmitting a specified power to the discharge electrode. More than two radio frequency power supplies and impedance matching networks can be added to apply power of different power and frequency.

[0041] exist Figure 1 In the process, when the etching gas supplied from the gas supply unit is supplied through the nozzle 30, the pressure in the process chamber reaches the specified pressure condition through the vacuum system (not shown) and the like. In this case, the substrate holder 20 fixes the substrate through the substrate fixing unit (not shown). When the specified pressure condition required for the process is reached, the specified power is applied from the RF power supply 50. In this case, the impedance matching network 40 transmits the maximum power to the substrate electrode 210 by matching the impedance of the RF power supply and the etching device. A strong AC electric field is generated between the nozzle 30 and the substrate holder 20 by the applied RF power, thereby generating plasma P. Radicals and ions are generated in the generated plasma P, and these generated components react chemically with the substrate, or etch the silicon-containing film formed on the substrate S by physical etching.

[0042] Figure 1 The etching device of the present invention has a structure in which a radio frequency power source is connected to the substrate support 20, but the etching device is not limited thereto, and a form in which a radio frequency power source is connected to the nozzle 30 to reduce physical etching can also be adopted. In addition, a coil antenna is provided in the etching device of the present invention to use inductively coupled plasma, and a radio frequency power source can be connected to the coil antenna. In addition, the etching device of the present invention can also have a form in which a separate remote plasma device for supplying only radicals and ions is combined with a process chamber.

[0043] Figure 2 Flow chart of the etching method according to an embodiment of the present invention. Figure 2 First, an etching gas for etching the substrate S including the silicon-containing film fixed on the substrate support 20 is supplied into the process chamber 10 of the etching device.

[0044] In this case, the silicon-containing film formed on the substrate S may include a silicon oxide film, a silicon nitride film, a polysilicon (p-Si) film, a silicide film, etc., including a first silicon-containing film and a second silicon-containing film as at least two silicon-containing films, and the first silicon-containing film and the second silicon-containing film are different from each other. According to an example of the present invention, a silicon nitride film can be selected as the first silicon-containing film, and a silicon oxide film can be selected as the second silicon-containing film. In addition, the etching method of the present invention can also be used to etch other types of silicon-containing films other than the silicon-containing films listed above.

[0045] The supplied etching gas includes a reaction gas containing nitrosyl fluoride (FNO) and an inert gas containing argon, helium, etc. The reaction gas and the inert gas are mixed in an appropriate ratio and supplied at a constant flow rate.

[0046] In this case, other control gases (H 2 , H 2 O, HBr, etc.). The ratio of reactive gas to inert gas can be adjusted by adding control gas.

[0047] When the etching gas is supplied to the process chamber 10, the pressure in the process chamber can be maintained at an appropriate pressure condition using a vacuum system (not shown) and the like. Also, as required, the temperature of the substrate S can be maintained at an appropriate temperature condition by a heater and a cooling water flow path (not shown) in the substrate support.

[0048] Next, under appropriate pressure and temperature conditions, appropriate power is applied to the etching device by the RF power supply 50, thereby generating plasma P in the process chamber 10. The free radicals and ions generated in the plasma P react with the silicon-containing film on the substrate S to form volatile by-products, thereby etching the etching object. In the etching step, the plasma is maintained for an appropriate time to form a desired ultrafine structure on the substrate.

[0049] Below, refer to Figures 3 to 5 , the etching rate and etching selectivity of the silicon-containing film are described when the pressure condition is 500mTorr when the etching gas containing nitrosyl fluoride (FNO) generates direct plasma. Figures 3 to 5 In the example above, NF will be used. 3The case of using a conventional reaction gas is referred to as a "comparative example", and the case of using nitrosyl fluoride (FNO) of the present invention is referred to as an "exemplary example".

[0050] Figure 3 Graph showing the etching rate of silicon nitride film (SiN) as a function of the ratio of reactive gas to inactive gas under a pressure of 500 mTorr when direct plasma is generated by flowing the etching gas into the etching apparatus at a total flow rate of 200 sccm in the direct plasma generating step.

[0051] Figure 4 To illustrate the plasma generation step, when Figure 3 When direct plasma is generated under the same conditions, the silicon oxide film (SiO 2 ) is a graph showing the etching rate of the catalyst as a function of the ratio of reactive gas to inactive gas.

[0052] Figure 5 The ratio of the reactive gas to the inert gas in the plasma generation step and the etching selectivity of the silicon nitride film to the silicon oxide film under the pressure condition of 500 mTorr are shown.

[0053] like Figure 3 As shown in FIG. 1 , when a silicon nitride film is etched by direct plasma of an etching gas containing nitrosyl fluoride (FNO), the etching rate of the silicon nitride film decreases in proportion to the increase in the ratio of argon gas relative to the ratio of the reaction gas containing nitrosyl fluoride (FNO) to the inert gas containing argon gas. That is, Figure 3 In the graph, the slope of the etching rate relative to the argon gas ratio is negative.

[0054] On the other hand, Figure 4 As shown in FIG. 1 , when a silicon oxide film is etched by direct plasma of an etching gas containing nitrosyl fluoride (FNO), the etching rate of the silicon oxide film increases in proportion to the increase in the ratio of argon gas relative to the ratio of the reaction gas containing nitrosyl fluoride (FNO) to the inactive gas containing argon gas, and thus Figure 4 In the graph, the slope of the etching rate relative to the argon gas ratio is positive.

[0055] When manufacturing semiconductor devices, there are cases where the etching selectivity ratio of the silicon nitride film to the silicon oxide film must be as large as possible. For this reason, it is necessary to maintain the conditions under which the etching rate of the silicon oxide film is as low as possible and the etching rate of the silicon nitride film is as high as possible. Figure 3 and Figure 4As shown, when a silicon nitride film and a silicon oxide film are etched using a direct plasma of an etching gas composed of a mixture of a reaction gas containing nitrosyl fluoride (FNO) and an inert gas containing argon gas, the etching rate activities of the silicon nitride film and the silicon oxide film are different from each other depending on the ratio and pressure of the reaction gas to the inert gas. Therefore, by utilizing this point, when a direct plasma of an etching gas containing nitrosyl fluoride (FNO) is generated, the etching selectivity of the silicon nitride film to the silicon oxide film can be greatly improved by appropriately adjusting the ratio and pressure of the reaction gas / inert gas.

[0056] from Figure 5 It can be seen that compared with the previous use of NF 3 Compared with the case of using nitrosyl fluoride (FNO) as a reactive gas (comparative example), it can be seen that the etching selectivity of the silicon nitride film relative to the silicon oxide film is improved when using nitrosyl fluoride (FNO) according to the present invention (exemplary embodiment). In addition, as the ratio of the inert gas to the entire etching gas increases, the etching selectivity of the silicon nitride film relative to the silicon oxide film can be increased.

[0057] In the present invention, the pressure condition can be adjusted within a range of, for example, 100 to 1000 mTorr, for example, 100 to 800 mTorr, for example, 200 to 700 mTorr, for example, 300 to 600 mTorr, for example, 350 to 500 mTor. Within the above pressure range, as the ratio of the inactive gas to the etching gas increases, the etching rate of the silicon nitride film decreases, while the etching rate of the silicon oxide film increases, thereby improving the selectivity.

[0058] from Figures 3 to 5 It can be seen that by increasing the proportion of inactive gas, the selectivity can be increased, but if the proportion of inactive gas is too high, the proportion of reactive gas may be reduced, thereby reducing etching performance. From this point of view, based on the total content of reactive gas and inactive gas as 100 vol%, preferably, the content of reactive gas is, for example, 20 vol% or more, for example, 25 vol% or more. Moreover, based on the total content of reactive gas and inactive gas as 100 vol%, the proportion of inactive gas can range from 0 to 80 vol%, and can range from 25 to 75 vol%.

[0059] However, the present invention is not limited to this. Even if the signs of the slopes of the etching rate curves are the same, if the absolute values ​​of the slopes of the etching rates of the silicon nitride film and the silicon oxide film with pressure are different, the etching selectivity of the silicon nitride film relative to the silicon oxide film can be increased by adjusting the pressure conditions.

[0060] That is, within a specified pressure range, as the ratio of inert gas to etching gas increases, or as pressure increases, by finding a pressure range in which the rates of change of the etching rates of silicon nitride film and silicon oxide film are different, pressure conditions can be selected to maximize the etching selectivity.

[0061] The present invention is described in more detail above with reference to the embodiments and drawings of this specification, but the present invention is not necessarily limited to these embodiments and drawings, and various modifications can be made without departing from the technical ideas of this specification. Therefore, the embodiments and drawings disclosed in this specification are not used to limit the technical ideas of this specification, but to illustrate the technical ideas of this specification, and the scope of the technical ideas of this specification is not limited by these embodiments. Therefore, the above embodiments should be understood as illustrative and non-restrictive in all aspects. The scope of protection of this specification should be interpreted according to the scope of protection claimed by the invention, and all technical ideas within the equivalent scope should be interpreted as included in the scope of rights of this specification.

Claims

1. A method for etching a silicon-containing film, characterized in that: The steps include: introducing a substrate including a first silicon-containing film and a second silicon-containing film into a process chamber of an etching device; Supplying etching gas containing reactive gas and inert gas to the process chamber; Generating free radicals of the etching gas in the process chamber maintained at a specified pressure; and etching the first silicon-containing film on the substrate using radicals of the etching gas, The above reaction gas contains nitrosyl fluoride gas, The predetermined pressure is set so that a sign of a slope of an etching rate of the first silicon-containing film with respect to pressure is different from a sign of a slope of an etching rate of the second silicon-containing film with respect to pressure.

2. The method for etching a silicon-containing film according to claim 1, wherein: The first silicon-containing film and the second silicon-containing film are different from each other and are independently selected from one of a silicon oxide film, a silicon nitride film, a polysilicon film and a silicide film.

3. The method for etching a silicon-containing film according to claim 1, wherein: The first silicon-containing film includes a silicon nitride film. The second silicon-containing film includes a silicon oxide film.

4. The method for etching a silicon-containing film according to claim 1, wherein: The content of the reaction gas is greater than or equal to 20 vol % based on the total content of the reaction gas and the inert gas being 100 vol %.

5. The method for etching a silicon-containing film according to claim 1, wherein: The inert gas includes one or more of argon, nitrogen and helium.

6. The method for etching a silicon-containing film according to claim 1, wherein: The above-mentioned prescribed pressure is adjusted within the range of 100 mTorr to 1 Torr.

7. The method for etching a silicon-containing film according to claim 1, wherein: The above-mentioned specified pressure is adjusted within the range of 350 mTorr to 500 mTor.

8. The method for etching a silicon-containing film according to claim 1, wherein: The step of forming radicals of the etching gas includes a plasma etching method.

9. The method for etching a silicon-containing film according to claim 8, wherein: The above-mentioned plasma etching method is one of capacitively coupled plasma method, inductively coupled plasma method, remote plasma system method, electron cyclotron resonance plasma method, transformer coupled plasma method, high-density plasma method, active ion etching and magnetic enhanced reactive ion etching.

10. A method for manufacturing a semiconductor device, characterized in that: A method for etching a silicon-containing film according to any one of claims 1 to 9.

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