Method of etching silicon-containing film and method of 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] In general, a series of processes such as deposition, etching, ion implantation, cleaning, etc. are performed to manufacture semiconductor devices. These processes are performed under various process conditions such as atmospheric pressure, low pressure, vacuum, etc. in a process chamber capable of maintaining the process conditions. Among these, the etching process is a process in which a portion of a thin film formed on a substrate by a deposition process, etc. is selectively removed to form a desired shape of ultrafine structure (pattern, etc.).

[0003] In an etching process, particularly a dry etching process, an etching gas in a gaseous state is injected, and the injected etching gas reacts with an etching target (e.g., a silicon-containing film) on a substrate to form a volatile by-product, thereby removing a part or the whole of a thin film. In a dry etching process, a plasma etching method is mainly used, which uses active ions or generally utilizes plasma to increase the reactivity between the etching gas and the etching target. In a plasma etching method, an etching gas is made into plasma to form highly reactive radicals and ions, and these active species (radicals) and ions (ions) physically or chemically etch the etching target.

[0004] Dry etching processes include plasma etching methods, such as Capacitively Coupled Plasma (CCP) method, Inductively 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), Magnetically Enhanced Reactive Ion Etching (Magnetic Enhanced RIE), etc.

[0005] Direct plasma technology is mainly used to create plasma from etching gas. Direct plasma technology is a method in which power is applied directly to the process chamber, such as CCP (Capacitively Coupled Plasma) or ICP (Inductively Coupled Plasma), and the plasma generated 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 an etching process, in order to form a desired ultra-fine structure, the target to be etched must have a high etch rate, whereas 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 become 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 include perfluoro-compound gases such as CF4, C3F6, SF6, and NF3, which have been used in large quantities. However, the waste gas discharged after the etching process from existing perfluoro-compound reactive gases is difficult to treat, and high treatment costs are required before discharging the gas into the atmosphere. In addition, conventional perfluoro-compound gases have a long lifespan in the atmosphere and a very high global warming potential (GWP), and are considered to be a major cause of climate change.

[0008] This has created a demand for alternative reactive gases that have a 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 is intended to solve the problems of the conventional technology, and aims to provide a method for etching a silicon-containing film using an environmentally friendly etching gas having a low global warming potential instead of a conventional reactive gas containing a perfluoro compound gas as a dry etching method.

[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 object of the present invention is not limited to the object mentioned above, and other objects and advantages of the present invention not mentioned can be understood from the following description and can be more clearly understood from the embodiments of the present invention. In addition, it can be easily understood that the object and advantages of the present invention can be realized by the means and combinations thereof as 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 by the active species (radical) of the etching gas, wherein the reactive gas includes FNO gas, and the predetermined pressure is set such that a sign of a slope of an etching rate of the first silicon-containing film versus pressure is different from a sign of a slope of an 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 an 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 one 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, the method including the method for etching a silicon-containing film according to an aspect of the present invention. Effect of the Invention

[0022] According to the present invention, the etching gas containing FNO has an 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 with reference to the following detailed description of the preferred embodiments of the present invention. [Brief description 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; [Diagram 2] 1 is a flow diagram of a method for etching a silicon-containing film according to an embodiment of the present invention. [Diagram 3] 1 is a graph showing an 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 an etching rate of a silicon oxide film depending on the ratio of etching gases, pressure, and applied power. [Diagram 5] 1 is a graph showing the selectivity of a silicon nitride film and a silicon oxide film depending on the ratio of etching gases, pressure, and applied power. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The above-mentioned objects, features and advantages will be described in detail hereinafter with reference to this specification, so that a person having ordinary skill in the art to which the present invention pertains 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 the elements in this specification are described as "comprising," "having," "consisting," "disposed," "equipped," etc., other elements may be added unless "only" is used. When an element is expressed in the singular, it includes the plural unless otherwise expressly stated.

[0028] When interpreting the elements in this specification, they are interpreted as including 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 using a capacitively coupled plasma (CCP) as an example, among etching apparatuses including a process chamber for performing an etching method according to an embodiment of the present invention. The etching apparatus is configured to generate plasma (P) by applying a predetermined power while maintaining a predetermined pressure condition, and includes a process chamber 10, a substrate holder 20, a shower head 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 easily generate plasma (P) near the surface of the substrate (S) or to easily cause a chemical reaction. 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 and after processing. A vacuum system (not shown) including a vacuum pump may be connected to the process chamber 10 so that the process chamber 10 can reach and maintain a specific pressure condition.

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

[0032] An etching gas including a reactive gas and an inert gas may be supplied to the shower head 30 at a constant flow rate by a gas supply unit and 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 generating direct plasma.

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

[0034] In FIG. 1, when an etching gas is supplied from a gas supply unit through the shower head 30, the pressure in the process chamber reaches a predetermined pressure condition by a vacuum system (not shown). At this time, the substrate holder 20 fixes the substrate by a substrate fixing means (not shown). When the predetermined pressure condition required for the process is reached, a predetermined power is applied by the RF power source 50. At this time, the impedance matching network 40 matches the impedance of the RF power source and the etching device, and transmits the maximum power to the substrate electrode 210. A strong AC electric field is generated between the shower head 30 and the substrate holder 20 by the applied RF power source, and plasma (P) is generated. Radicals and ions are generated in the generated plasma (P), and the components thus generated chemically react with the substrate or physically etch 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 thereto, and may have a configuration in which an RF power source is connected to the shower head 30 in order to reduce physical etching. Also, the etching apparatus of the present invention may have a coil antenna disposed therein and an RF power source connected to the coil antenna in order to use ICP (Inductively Coupled Plasma). Also, the etching apparatus of the present invention may have a configuration in which a separate remote plasma device is coupled to the process chamber in order 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] At this time, 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, and the first silicon-containing film and the second silicon-containing film are different from each other. According to an embodiment of the present invention, the first silicon-containing film may be selected as a silicon nitride film, and the second silicon-containing film may be selected as a silicon oxide film. In addition, the etching method of the present invention may be applied to etching other types of silicon-containing films in addition to the silicon-containing films listed above.

[0038] The etching gas 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 included depending on the etching target or etching process. The ratio of the reactive gas and the inert gas can be adjusted according to the added control gas.

[0040] 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 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 via a heater and a cooling water passage (not shown) in the substrate holder.

[0041] Then, under appropriate pressure and temperature conditions, 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. 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 etch 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, with reference to FIG. 3 to FIG. 5, the etching rate and etching selectivity of a silicon-containing film when the pressure condition when generating direct plasma of an etching gas containing FNO is 500 mTorr will be described. In FIG. 3 to FIG. 5, the case where NF3 is used as a conventional reactive gas is designated as a "Comparative Example", and the case where FNO is used according to the present invention is designated as an "Example".

[0043] FIG. 3 is a graph showing the etching rate of silicon nitride film (SiN) 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 under a pressure condition of 500 mTorr when direct plasma is generated under the same conditions as in FIG. 3 during the plasma generation stage.

[0045] FIG. 5 shows the etching selectivity of a silicon nitride film to a silicon oxide film under the conditions of the ratio of the reactive gas and the inert gas in the plasma generation stage and the pressure of 500 mTorr.

[0046] As shown in Fig. 3, in the etching of silicon nitride film by direct plasma of etching gas containing FNO, the etching rate of silicon nitride film decreases in proportion to the ratio of argon in the ratio of reactive gas containing FNO and inert gas containing argon. That is, in Fig. 3, the slope of the etching rate with respect to the 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 and the inert gas containing argon, and therefore the slope of the etching rate with respect to the ratio of argon gas in FIG. 4 is positive.

[0048] In the manufacture of semiconductor devices, there are cases where the etching selectivity of silicon nitride film to silicon oxide film must be as high as possible. To achieve this, under the same conditions, the etching rate of silicon oxide film must be as low as possible and the etching rate of silicon nitride film must be as high as possible. As shown in Figures 3 and 4, in the etching of silicon nitride film and silicon oxide film by direct plasma using an etching gas in which a reactive gas containing FNO and an inert gas containing argon gas are mixed, the behavior of the etching rates of silicon nitride film and silicon oxide film depending on the ratio of reactive gas to inert gas and pressure is different from each other. Therefore, when using this to generate direct plasma of an etching gas containing FNO, the etching selectivity of silicon nitride film to silicon oxide film can be greatly improved by appropriately adjusting the ratio of reactive gas / inert gas and pressure.

[0049] As can be seen from Fig. 5, when FNO is used according to the present invention (Example) compared to the conventional case where NF3 is used as a reactive gas (Comparative Example), the etching selectivity ratio of silicon nitride film to silicon oxide film is improved. Also, by increasing the ratio of inert gas to the total etching gas, the etching selectivity ratio 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, for example, 350 to 500 mTorr. As the ratio of the inert gas to the 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, so that the selectivity can be improved.

[0051] As can be seen from Figures 3 to 5, increasing the proportion of inert gas can increase the selectivity, but if the proportion of inert gas is too high, the proportion of reactive gas will be low, and etching performance may be reduced. From this perspective, based on a total content of reactive gas and inert gas of 100 vol%, the reactive gas is preferably contained at, for example, 20 vol% or more, for example, 25 vol% or more. 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 sign of the slope of the etching rate graph is 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 from each other, the etching selectivity ratio 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 given pressure range or by increasing the pressure, a pressure range in which the change rates of the etching rates of the silicon nitride film and the silicon oxide film differ can be found, and pressure conditions can be selected so that the etching selectivity 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, but this specification is not necessarily limited to these examples and drawings, and various modifications can be made within the scope of the technical idea of ​​this specification. Therefore, the examples and drawings disclosed in this specification are for illustration purposes and not for the purpose of limiting the technical idea of ​​this specification, and the scope of the technical idea of ​​this specification is not limited by these examples. Therefore, it should be understood that the examples described above are illustrative and not limiting in all respects. The scope of protection of this specification should be interpreted by the scope of the claims, and any technical idea within the equivalent scope should be interpreted as being included in the scope of the rights of this specification. [Explanation of symbols]

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

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, to the process chamber; forming activated species of an etching gas in the process chamber maintained at a predetermined pressure; Etching the first silicon-containing film on the substrate with radicals of the etching gas; Including, The reaction gas includes FNO gas, the predetermined pressure is set such 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; A method for etching a silicon-containing film.

2. 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 .

3. 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 .

4. The reactive gas is 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. The method for etching a silicon-containing film according to claim 1 .

5. The inert gas includes at least one of argon (Ar), nitrogen (N2), and helium (He); The method for etching a silicon-containing film according to claim 1 .

6. The predetermined pressure is adjusted within a range of 100 mTorr to 1 Torr. 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 the 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, 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, a reactive ion etching (RIE), and a magnetically enhanced reactive ion etching (MAE). Enhanced Reactive Ion Etching, Magnetically Enhanced 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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