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

Abstract

To provide a method of etching a silicon-containing film, and more specifically, a method of etching a silicon-containing film using an etching gas containing FNO, and a method of manufacturing a semiconductor device including the same.SOLUTION: A method of etching a silicon-containing film includes the steps of: 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 including a reaction gas and an inert gas to the process chamber; forming active species of the etching gas in the process chamber that is maintained at a predetermined pressure; and etching the first silicon-containing film on the substrate by the active species of the etching gas. The reaction gas includes a FNO gas. The predetermined pressure is set so that a sign of a slope of an etch rate of the first silicon-containing film with respect to pressure differs from a sign of an etch rate of the second silicon-containing film with respect to pressure.SELECTED DRAWING: Figure 2

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 FNO, and a method for manufacturing a semiconductor device including the same. [Background technology]

[0002] Typically, a series of processes such as deposition, etching, ion implantation, cleaning, etc. are performed to manufacture semiconductor devices. These processes are performed in a process chamber capable of maintaining the process conditions under various process conditions such as atmospheric pressure, low pressure, vacuum, etc. Among these processes, the etching process is a process of selectively removing a portion of a thin film formed on a substrate by a deposition process, etc., to form an ultrafine structure (e.g., a pattern) of a desired shape.

[0003] Etching processes, particularly dry etching processes, involve injecting a vapor-phase etching gas and reacting it with the target to be etched (e.g., a silicon-containing film) on a substrate to form volatile by-products, thereby removing part or all of the thin film. Dry etching processes typically involve plasma etching, which uses active ions or plasma to enhance the reactivity between the etching gas and the target to be etched. Plasma etching converts an etching gas into plasma to form highly reactive radicals and ions, which then physically or chemically etch the target to be etched.

[0004] Dry etching processes 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), and Magnetically Enhanced Reactive Ion Etching (Magnetic Enhanced RIE).

[0005] Direct plasma technology is mainly used to create plasma from etching gas. Direct plasma technology, such as CCP (Capacitively Coupled Plasma) or ICP (Inductively Coupled Plasma), is a method in which power is applied directly to the process chamber, generating plasma that directly contacts the substrate and the object to be etched. In this case, inert gases such as helium (He), nitrogen (N2), and argon (Ar) are mixed and injected to help create plasma from the etching gas and accelerate physical etching.

[0006] In order to form a desired ultrafine structure in an etching process, the target to be etched must have a high etch rate, while the thin film that is not desired to be etched must have a low etch rate. The ratio of the etch rate of the thin film to be etched to the etch rate of the thin film that is not desired to be etched is called selectivity, and a reaction gas with a high selectivity is required for the etching process. In particular, in recent years, it has been necessary to develop a reaction gas with a higher selectivity in order to manufacture semiconductor devices that can be miniaturized or highly integrated.

[0007] Conventional reactive gases have been used in large quantities as perfluorochemical gases, such as CF4, C3F6, SF6, and NF3. However, the waste gases emitted after the etching process from existing perfluorochemical reactive gases are difficult to treat, and require high treatment costs before being released into the atmosphere. Furthermore, conventional perfluorochemical gases have a long atmospheric lifetime and a very high global warming potential (GWP), making them a major cause of climate change.

[0008] This has created a demand for alternative reactive gases that have low global warming potential and excellent etching performance, particularly selectivity, for silicon-containing films. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the problems of the conventional technology, and an object of the present invention is to provide a dry etching method for etching a silicon-containing film using an environmentally friendly etching gas with a low global warming potential instead of a conventional reactive gas containing a perfluoro compound gas.

[0010] Another object of the present invention is to provide a method for etching a silicon-containing film with a high selectivity by assisting in plasma generation and activating an etching gas containing an inert gas (such as argon) that performs physical etching into plasma.

[0011] Another object of the present invention is to provide a method for manufacturing a semiconductor device, which includes the method for etching a silicon-containing film.

[0012] The objects of the present invention are not limited to those mentioned above, and other objects and advantages of the present invention not mentioned above can be understood from the following description and can be more clearly understood from the examples of the present invention. Furthermore, it can be easily understood that the objects and advantages of the present invention can be achieved by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0013] In order to achieve the above object, according to one aspect of the present invention, there is provided a method for etching a silicon-containing film, the method including: introducing a substrate including a first silicon-containing film and a second silicon-containing film into a process chamber of an etching apparatus; supplying an etching gas including a reactive gas and an inert gas into the process chamber; forming active species of the etching gas in the process chamber maintained at a predetermined pressure; and etching the first silicon-containing film on the substrate with the active species (radicals) of the etching gas, wherein the reactive gas includes FNO gas, and the predetermined pressure is set such that the sign of the slope of the etching rate of the first silicon-containing film versus pressure is different from the sign of the slope of the etching rate of the second silicon-containing film versus pressure.

[0014] The first silicon-containing film and the second silicon-containing film may be different from each other and may be independently selected from any one of a silicon oxide film, a silicon nitride film, a polysilicon film, and a silicide film.

[0015] The first silicon-containing film may include a silicon nitride film, and the second silicon-containing film may include a silicon oxide film.

[0016] The reactive gas may be contained in an amount of 20 vol% or more, based on 100 vol% of the total content of the reactive gas and the inert gas.

[0017] The inert gas may include any one or more of argon (Ar), nitrogen (N2), and helium (He).

[0018] The predetermined pressure may be adjusted within a range of 100 mTorr to 1 Torr, and according to one embodiment, may be adjusted within a range of 350 mTorr to 500 mTorr.

[0019] The step of forming activated species of the etching gas may include a plasma etching method.

[0020] The plasma etching method may be any of a capacitively coupled plasma (CCP) method, an inductively coupled plasma (ICP) method, a remote plasma system (RPS) method, a plasma method using electron cyclotron resonance (ECR), a transformer coupled plasma (TCP) method, a high density plasma (HDP) method, reactive ion etching (RIE), and magnetically enhanced reactive ion etching (Magnetic Enhanced RIE).

[0021] According to another aspect of the present invention, there is provided a method for manufacturing a semiconductor device, including the method for etching a silicon-containing film according to an aspect of the present invention. [Effects of the Invention]

[0022] According to the present invention, an etching gas containing FNO has the effect of being environmentally friendly with a low global warming potential (GWP), and capable of etching a silicon-containing film with a high selectivity.

[0023] The above-mentioned effects and specific effects of the present invention will be described below while explaining the embodiments of the invention. [Brief explanation of the drawings]

[0024] [Figure 1] 1 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; [Figure 2] 1 is a flow chart of a method for etching a silicon-containing film according to an embodiment of the present invention. [Figure 3] 1 is a graph showing the etching rate of a silicon nitride film depending on the ratio of etching gases, pressure, and applied power. [Figure 4] 1 is a graph showing the etching rate of a silicon oxide film depending on the ratio of etching gases, pressure, and applied power. DETAILED DESCRIPTION OF THE INVENTION

[0025] The above-mentioned objects, features and advantages will be described in detail below with reference to this specification, so that those skilled in the art can easily implement the technical concept of the present invention.

[0026] In describing this specification, if a detailed description of related publicly known techniques is deemed to obscure the gist of this specification, the detailed description will be omitted.

[0027] When elements in this specification are described as "comprising," "having," "consisting," "arranged," "comprising," etc., other elements may be added unless the word "only" is used. When elements are expressed in the singular, this includes the plural unless otherwise expressly stated.

[0028] When interpreting the elements in this specification, it is understood that they include a margin of error unless otherwise expressly stated.

[0029] The present invention will be described in more detail below.

[0030] FIG. 1 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, exemplarily illustrating an etching apparatus using a capacitively coupled plasma (CCP). The etching apparatus is configured to maintain a predetermined pressure condition and apply a predetermined power to generate plasma (P). It includes a process chamber 10, a substrate holder 20, a showerhead 30, an impedance matching network 40, an RF power supply 50, a gas supply unit, and the like. The substrate (S) includes a silicon semiconductor substrate including a silicon-containing film. The etching apparatus 1 may be configured to facilitate the generation of plasma (P) or facilitate a chemical reaction near the surface of the substrate (S). The process chamber 10 is configured to maintain a predetermined pressure condition during processing and may further include a substrate insertion device (not shown) for inserting a substrate before or after processing. A vacuum system (not shown) including a vacuum pump may be connected to the process chamber 10 to achieve and maintain a specific pressure condition.

[0031] The substrate holder 20 is configured to hold a substrate (S) for processing and generate direct plasma. The substrate holder 20 includes a discharge electrode 210 for applying power to an etching gas in the processing chamber to generate direct plasma. Although not shown in FIG. 1 , the substrate holder 20 may also include a heater and a cooling water flow path for controlling the temperature of the substrate (S) during processing. Although not shown in FIG. 1 , the substrate holder 20 may also include a substrate fixing means such as an electrostatic chuck for fixing the substrate (S) during processing.

[0032] An etching gas including a reactive gas and an inert gas may be supplied at a constant flow rate by a gas supply unit to the shower head 30 and then injected into the process chamber 10. In this case, the gas supply unit may include a gas supply system including a mass flow controller (MFC) to maintain a constant flow rate of the etching gas. Although not shown in FIG. 1, an RF power source and an impedance matching system may be further connected to the shower head 30 for direct plasma generation.

[0033] In a process chamber of an etching apparatus, an RF power supply 50 and an impedance matching network 40 are configured to be connected to a discharge electrode 210 to generate direct plasma. The RF power supply and the impedance matching network transmit a predetermined power to the discharge electrode to form direct plasma. Two or more RF power supplies and impedance matching networks can be added to apply powers of different power and frequency.

[0034] In FIG. 1, etching gas supplied from a gas supply unit is supplied through the showerhead 30, and the pressure in the process chamber reaches a predetermined pressure condition via a vacuum system (not shown). The substrate holder 20 then secures the substrate using a substrate securing means (not shown). Once the predetermined pressure condition required for the process is reached, the RF power supply 50 applies a predetermined power. The impedance matching network 40 matches the impedance of the RF power supply and the etching system to transmit maximum power to the substrate electrode 210. A strong AC electric field is generated between the showerhead 30 and the substrate holder 20 by the applied RF power, generating plasma (P). Radicals and ions are generated in the generated plasma (P). These generated components chemically react with or physically etch the substrate, thereby etching the silicon-containing film formed on the substrate (S).

[0035] 1 has a structure in which an RF power source is connected to the substrate holder 20, the etching apparatus is not limited to this, and an RF power source can also be connected to the showerhead 30 to reduce physical etching. Furthermore, the etching apparatus of the present invention may be provided with a coil antenna and connected to an RF power source to use ICP (Inductively Coupled Plasma). Furthermore, the etching apparatus of the present invention may have a configuration in which a separate remote plasma device is coupled to the process chamber to supply only radicals and ions.

[0036] 2 is a flow chart of an etching method according to an embodiment of the present invention. First, an etching gas is supplied to etch a substrate (S) including a silicon-containing film, which is fixed to a substrate holder (20) in a process chamber (10) of an etching apparatus.

[0037] 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., and the at least two types of silicon-containing films include a first silicon-containing film and a second silicon-containing film, the first silicon-containing film and the second silicon-containing film being different from each other. According to one embodiment of the present invention, the first silicon-containing film may be a silicon nitride film, and the second silicon-containing film may be a silicon oxide film. In addition to the silicon-containing films listed above, the etching method of the present invention may also be applied to etching other types of silicon-containing films.

[0038] The etching gas to be supplied includes a reactive gas containing FNO and an inert gas containing argon, helium, etc., and the reactive gas and the inert gas are mixed in an appropriate ratio and supplied at a constant flow rate.

[0039] In this case, different control gases (H2, H2O, HBr, etc.) may be further added depending on the etching target or etching process. The ratio of reactive gas to inert gas can be adjusted depending on the added control gas.

[0040] Once 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 device such as a vacuum system (not shown). In addition, if necessary, the temperature of the substrate (S) can be maintained at an appropriate temperature condition through a heater and a cooling water flow path (not shown) in the substrate holder.

[0041] Next, a plasma (P) is generated in the process chamber 10 by applying an appropriate power to the etching device via the RF power supply 50 under appropriate pressure and temperature conditions. The activated species 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 target. The plasma is maintained for an appropriate time during the etching step to form the desired nanostructure on the substrate.

[0042] In the following, Figs. 4 , the etching rate and etching selectivity of a silicon-containing film when the pressure condition for generating direct plasma of an etching gas containing FNO is 500 mTorr are described, and FIGS. 4 In the present example, a case where NF3 was used as a conventional reactive gas was designated as a "Comparative Example," and a case where FNO was used according to the present invention was designated as an "Example."

[0043] FIG. 3 is a graph showing the etching rate of silicon nitride (SiN) film depending on the ratio of reactive gas to inert gas under a pressure condition of 500 mTorr when direct plasma is generated while flowing etching gas at a total flow rate of 200 sccm in the etching equipment during the direct plasma generation stage.

[0044] FIG. 4 is a graph showing the etching rate of a silicon oxide film (SiO2) depending on the ratio of reactive gas to inert gas at a pressure of 500 mTorr when direct plasma is generated under the same conditions as in FIG. 3 during the plasma generation stage.

[0045] P The ratio of reactive gas to inert gas during plasma generation and the etching selectivity of silicon nitride film to silicon oxide film under 500 mTorr pressure conditions. Consider .

[0046] As shown in Figure 3, when etching a silicon nitride film using direct plasma with an etching gas containing FNO, the etching rate of the silicon nitride film decreases in proportion to the ratio of argon in the FNO-containing reactive gas to the inert gas containing argon. In other words, in Figure 3, the slope of the etching rate versus ratio is negative.

[0047] On the other hand, as shown in FIG. 4, in the etching of a silicon oxide film by direct plasma of an etching gas containing FNO, the etching rate of the silicon oxide film increases in proportion to the ratio of argon in the ratio of the reactive gas containing FNO to the inert gas containing argon. Therefore, the slope of the etching rate with respect to the ratio of argon gas in FIG. 4 is positive.

[0048] In the fabrication of semiconductor devices, it is sometimes necessary to maximize the etching selectivity of silicon nitride films relative to silicon oxide films. To achieve this, it is necessary to maintain conditions that minimize the etching rate of silicon oxide films while simultaneously maintaining the highest etching rate of silicon nitride films under the same conditions. As shown in Figures 3 and 4, when etching silicon nitride films and silicon oxide films using direct plasma with an etching gas mixture of a reactive gas containing FNO and an inert gas containing argon, the behavior of the etching rates of silicon nitride films and silicon oxide films depending on the ratio of the reactive gas to the inert gas and the pressure differs. Therefore, when generating direct plasma with an etching gas containing FNO, the etching selectivity of silicon nitride films relative to silicon oxide films can be significantly improved by appropriately adjusting the ratio and pressure of the reactive gas / inert gas.

[0049] Follow As shown above, when FNO is used as the reactive gas (Example) according to the present invention, the etching selectivity of silicon nitride film to silicon oxide film is improved compared to when NF3 is used as the reactive gas (Comparative Example). Also, by increasing the ratio of inert gas to the total etching gas, the etching selectivity of silicon nitride film to silicon oxide film can be increased.

[0050] The pressure condition in the present invention can be adjusted within a range of, for example, 100 to 1,000 mTorr, for example, 100 to 800 mTorr, for example, 200 to 700 mTorr, for example, 300 to 600 mTorr, or for example, 350 to 500 mTorr. As the ratio of inert gas to etching gas increases within the pressure range, the etching rate of the silicon nitride film decreases, but the etching rate of the silicon oxide film increases. do.

[0051] No If the proportion of active gas is too high, the proportion of reactive gas will be low, which may result in poor etching performance. From this perspective, the reactive gas is preferably contained at 20 vol% or more, for example, 25 vol% or more, based on a total content of reactive gas and inert gas of 100 vol%. Furthermore, based on a total content of reactive gas and inert gas of 100 vol%, the proportion of inert gas may be in the range of 0 to 80 vol%, or may be in the range of 25 to 75 vol%.

[0052] However, the present invention is not limited to this. Even if the signs of the slopes of the etching rate graphs are the same, if the absolute values ​​of the slopes of the etching rates of the silicon nitride film and the silicon oxide film depending on the pressure are different, the etching selectivity of the silicon nitride film to the silicon oxide film can be increased by adjusting the pressure conditions.

[0053] That is, by increasing the ratio of the inert gas to the etching gas within a predetermined pressure range or by increasing the pressure, a pressure range can be found in which the change rates of the etching rates of the silicon nitride film and the silicon oxide film differ, and pressure conditions can be selected so that the etching selectivity ratio is maximized.

[0054] As described above, the present invention has been described in more detail with reference to the examples and drawings of this specification. However, this specification is not necessarily limited to these examples and drawings, and various modifications can be made within the scope of the technical concept of this specification. Therefore, the examples and drawings disclosed in this specification are for illustrative purposes only, not for the purpose of limiting the technical concept of this specification, and these examples do not limit the scope of the technical concept of this specification. Therefore, the above-described examples should be understood as illustrative in all respects and not limiting. The scope of protection of this specification should be interpreted by the scope of the claims, and any technical concept within the scope equivalent thereto should be interpreted as being included in the scope of rights of this specification. [Explanation of symbols]

[0055] 10...process chamber, 20...substrate holder, 30...showerhead, 40...impedance matching network, 50...RF power supply.

Claims

1. 1. A method for etching a silicon-containing film, comprising: introducing a substrate including a first silicon-containing film and a second silicon-containing film into a process chamber of an etching apparatus; supplying an etching gas including a reactive gas and an inert gas into the process chamber; forming activated species of an etching gas containing the inert gas in a ratio of 25 to 75 vol % based on a total content of the reaction gas and the inert gas of 100 vol % in the process chamber maintained at a predetermined pressure; selectively etching the first silicon-containing film with respect to the second silicon-containing film on the substrate with radicals of the etching gas; Including, The reaction gas includes FNO gas, the predetermined pressure is adjusted within a range of 100 mTorr to 1 Torr so that the sign of a slope of the etching rate of the first silicon-containing film relative to the ratio differs from the sign of a slope of the etching rate of the second silicon-containing film relative to the ratio; Method for etching silicon-containing films.

2. The predetermined pressure is adjusted within a range of 100 mTorr to 1 Torr so that the sign of the slope of the etching rate of the first silicon-containing film relative to the rate is negative and the sign of the slope of the etching rate of the second silicon-containing film relative to the rate is positive. The method for etching a silicon-containing film according to claim 1 .

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

4. the first silicon-containing film includes a silicon nitride film; the second silicon-containing film includes a silicon oxide film; The method for etching a silicon-containing film according to claim 1 .

5. The reactive gas is contained in an amount of 25 vol% or more based on 100 vol% of the total content of the reactive gas and the inert gas. The method for etching a silicon-containing film according to claim 1 .

6. The inert gas includes at least one of argon (Ar), nitrogen (N), and helium (He). The method for etching a silicon-containing film according to claim 1 .

7. The predetermined pressure is adjusted within a range of 350 mTorr to 500 mTorr. The method for etching a silicon-containing film according to claim 1 .

8. The step of forming activated species of the etching gas includes a plasma etching method. The method for etching a silicon-containing film according to claim 1 .

9. The plasma etching method includes a capacitively coupled plasma (CCP) method, an inductively coupled plasma (ICP) method, and a Coupled Plasma (ICP) method, Remote Plasma System (RPS) method, Electron Cyclotron Resonance (ECR) plasma method, Transformer Coupled Plasma (TCP) method, High Density Plasma (HDP) method, Reactive Ion Etching (RIE), and Magnetically Enhanced Reactive Ion Etching (Magnetically Enhanced Reactive Ion Etching) method. RIE), The method for etching a silicon-containing film according to claim 8 .

10. A method for manufacturing a semiconductor device, comprising the method for etching a silicon-containing film according to any one of claims 1 to 9.

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