Dry-etching method for silicon oxide film

Abstract

To provide a method for dry-etching a silicon oxide layer capable of selectively etching a silicon oxide fine pattern.SOLUTION: A method for dry-etching a silicon oxide film includes a step of selectively etching a first layer by reacting an etching gas with a stacked structure including a first layer including the silicon oxide film and a second layer including the silicon oxide film and other material and stacked on the first layer. The first layer includes the silicon oxide film, and the etching step includes a step of self-limitingly reacting the etching gas with an exposed region of the first layer and a step of removing the self-limitingly reacted region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a dry etching method for a silicon oxide film, and more particularly to a dry etching method for selectively etching a silicon oxide film in a stacked structure. [Background technology]

[0002] Recently, as semiconductor manufacturing processes become finer, the number of processes that require precise control of the amount of etching while selectively etching silicon oxide (SiO2) films is increasing.

[0003] However, when using conventional wet etching to etch silicon oxide films, the etching selectivity is high but it is difficult to control the etching amount. Furthermore, wet etching proceeds isotropically, making it difficult to achieve fine layers. Another method for etching silicon oxide films is plasma etching. While plasma etching can achieve fine layers, its low etching selectivity makes it difficult to selectively remove the desired thin film. Additionally, plasma etching has the problem of damaging underlying films due to the plasma.

[0004] To address this problem, attempts have been made to etch silicon oxide using a dry method without using plasma. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Registration No. 11,715,641 B2 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a silicon oxide film dry etching method that is capable of selectively etching a silicon oxide fine pattern. [Means for solving the problem]

[0007] A method for dry etching a silicon oxide film according to an embodiment of the present invention includes the steps of: selectively etching a first layer including a silicon oxide film; and a second layer including a material different from the silicon oxide film and stacked on the first layer by reacting an etching gas including hydrogen fluoride, an amine compound, and an inert gas with a stack structure including the first layer, the first layer including a silicon oxide film; the etching step includes reacting the etching gas with an exposed region of the first layer in a self-limiting manner; and removing the self-limiting reacted region, the amine compound including at least one compound represented by the following Chemical Formula 1:

[0008] [ka] wherein R1 and R2 are each independently hydrogen or a substituted or unsubstituted aliphatic or aromatic hydrocarbon group having 1 to 12 carbon atoms (except when R1 and R2 are both hydrogen), and the substituted aliphatic or aromatic hydrocarbon group is substituted with nitrogen, oxygen, sulfur, phosphorus, and / or halogen atoms.

[0009] A method for dry etching a silicon oxide film according to an embodiment of the present invention includes a dry etching step of removing the silicon oxide film by reacting an etching gas containing hydrogen fluoride, an amine compound represented by Formula 1 above, and an inert gas with the silicon oxide film, wherein the dry etching step may include reacting the etching gas with exposed regions of the silicon oxide film in a self-limiting manner and removing the self-limiting reacted regions.

[0010] A method for manufacturing a semiconductor device according to an embodiment of the present invention includes selectively dry-etching a silicon oxide film on a semiconductor substrate having a stacked structure in which silicon oxide films and silicon nitride films are alternately stacked in a first direction by reacting an etching gas containing hydrogen fluoride, an amine compound represented by Formula 1, and an inert gas, wherein the selective dry-etching may include reacting the etching gas with exposed regions of the silicon oxide film in a self-limiting manner and removing the self-limiting reacted regions. [Effects of the Invention]

[0011] The present invention provides a dry etching method for silicon oxide films that allows selective etching of silicon oxide fine patterns.

[0012] According to the dry etching method for silicon oxide of the present invention, selective etching of silicon oxide is possible even at a low temperature of 100° C. or less without generating any residue that is reactive with the etching reaction. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a flow chart showing a method for dry etching a silicon oxide film according to an embodiment of the present invention; [Figure 2] 1 is a graph conceptually showing the adsorption degree of nitrogen-containing compounds, including ammonia, primary amine compounds, secondary amine compounds, and tertiary amine compounds, on the surface of a silicon oxide film, and the reactivity of hydrogen fluoride with the silicon oxide film. [Figure 3A] 1 is a diagram illustrating an example of a cross section of a stacked structure including a silicon oxide film that can be etched by an etching method according to an embodiment of the present invention. [Figure 3B] 1 is a diagram illustrating an example of a cross section of a stacked structure including a silicon oxide film that can be etched by an etching method according to an embodiment of the present invention. [Figure 3C]1 is a diagram illustrating an example of a cross section of a stacked structure including a silicon oxide film that can be etched by an etching method according to an embodiment of the present invention. [Figure 3D] 1 is a diagram illustrating an example of a cross section of a stacked structure including a silicon oxide film that can be etched by an etching method according to an embodiment of the present invention. [Figure 4] 1 is a conceptual diagram illustrating an etching apparatus according to an embodiment of the present invention; [Figure 5] FIG. 5 is a flow diagram showing a method for etching a silicon oxide film using the etching apparatus of FIG. [Figure 6] 1 is a graph showing the etching rate of a silicon oxide film as a function of time when the stage temperature is 35° C. and the pressure in the reactor is 3 Torr. [Figure 7A] 1 is a graph showing the amount of etching of an etching target depending on temperature, and also showing the etching selectivity of a specific etching target; [Figure 7B] 1 is a graph showing the amount of etching of an etching target depending on temperature, and also showing the etching selectivity of a specific etching target; [Figure 7C] 1 is a graph showing the amount of etching of an etching target depending on temperature, and also showing the etching selectivity of a specific etching target; [Figure 8] 1 is a graph showing the amount of etching of an etching target depending on temperature when hydrogen fluoride is used as an etching gas. [Figure 9] FIG. 1 is a cross-sectional view of a laminated structure used in Experimental Example B-1. [Figure 10] 1 is a graph showing the etching amount of each amine compound in Experimental Example B-1. [Figure 11] 10 is a SEM image showing a cross section of a laminated structure after etching has progressed in Experimental Example B-2. [Figure 12] FIG. 10 is a cross-sectional view of the laminated structure used in Experimental Example B-3. [Figure 13]10 is a cross-sectional SEM image showing the amount of etching when etching is performed using dimethylamine and trimethylamine in Experimental Example B-3. [Figure 14A] 1 is a graph showing etching behavior depending on pressure when the thickness of a silicon oxide film is 10 nm. [Figure 14B] 1 is a graph showing etching behavior depending on pressure when the thickness of a silicon oxide film is 10 nm. [Figure 15] 10 is a SEM cross-sectional image showing the etching results of Table 7 depending on the reaction time and amine compound. DETAILED DESCRIPTION OF THE INVENTION

[0014] In the following, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings, but the present invention is not limited to the embodiments described herein and may be embodied in different forms.

[0015] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and the like used in the specification and claims should be understood to be modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending on the desired properties obtained by the inventive subject matter of the present disclosure. As used herein, the term "about," when expressing a value or amount of mass, weight, time, volume, concentration, or percentage, is intended to encompass variations from the specified amount of ±20% in some embodiments, ±10%, ±5%, ±1%, ±0.55%, and ±0.1% in some embodiments, where such variations are appropriate for performing the disclosed methods.

[0016] Furthermore, units used in this specification without any special mention are based on weight, and for example, units such as % or ratio mean % by weight or weight ratio, and unless otherwise defined, % by weight means the weight % of any one component in the entire composition.

[0017] Furthermore, the numerical ranges used herein include the lower and upper limits, all values ​​within the range, increments logically derived from the form and width of the defined range, all doubly limited values, and all possible combinations of upper and lower limits of numerical ranges limited in different forms. Unless otherwise specified in the specification of the present invention, values ​​outside the numerical range that may occur due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0018] As used herein, the term "comprises" is an open-ended term having the same meaning as terms such as "comprising," "containing," "having," or "characterized by," and does not exclude additional, unrecited elements, materials, or steps. However, "comprising" may also be closed-ended or partly closed-ended, depending on the context.

[0019] One embodiment of the present invention relates to a method for selectively etching a silicon oxide film in a semiconductor manufacturing process using a dry etching process. More specifically, one embodiment of the present invention relates to a method for selectively removing only a silicon oxide film in a stacked structure in which a silicon oxide film and a different material are stacked. One embodiment of the present invention provides a method for effectively selectively removing a silicon oxide film without performing a heat treatment process to remove reaction products not used in the etching reaction. One embodiment of the present invention provides a method for selectively removing a silicon oxide film without using plasma, including a gas phase etching method in which an etching gas is injected into a reactor (chamber) and then a thin film is removed through a chemical reaction.

[0020] Preferred embodiments of the present invention will now be described in more detail with reference to the accompanying drawings.

[0021] FIG. 1 is a flow chart showing a method for dry etching a silicon oxide film according to one embodiment of the present invention.

[0022] 1, a method for dry etching a silicon oxide film according to an embodiment of the present invention includes reacting an etching gas with a silicon oxide film (S110) and removing the silicon oxide film (S120). The reacting of the etching gas with the silicon oxide film is a self-limiting reaction of the etching gas in exposed regions of the silicon oxide film. Reaction products of the self-limiting reaction are sequentially removed from the surface of the silicon oxide film. The self-limiting reaction and reaction product removal steps may be repeated N times (N is an integer greater than or equal to 0).

[0023] The silicon oxide etching process can be carried out in a reactor within an etching apparatus, which will be described later.

[0024] In one embodiment of the present invention, the step of self-limitingly reacting the etching gas with the exposed region of the silicon oxide film is performed by placing the substrate to be processed including the silicon oxide film in a reactor and supplying the etching gas into the reactor for a predetermined time at a predetermined flow rate. The reaction temperature of the silicon oxide film and the etching gas can be set within a predetermined range.

[0025] The etching gas reacts with the silicon oxide layer only on exposed regions of the silicon oxide layer, for example, on the surface of the silicon oxide layer exposed to the outside. As the reaction between the etching gas and the silicon oxide layer progresses, the exposed surface of the silicon oxide layer is covered with a reaction product of the etching gas and the silicon oxide layer. When the reaction product completely covers the exposed surface of the silicon oxide layer, the reaction rate between the etching gas and the silicon oxide layer decreases. The reaction product can be removed by purging. In one embodiment of the present invention, the silicon oxide layer is disposed in a structure in which a different type of film is stacked on the upper surface of the silicon oxide layer, and the exposed region of the silicon oxide layer may be a side surface of the silicon oxide layer, not the upper surface.

[0026] In one embodiment of the present invention, a sequence including reacting an etching gas with the exposed region of the silicon oxide film in a self-limiting manner and then removing the reaction product formed in the self-limiting reacted region can be repeated multiple times, for example, two, five, or ten times.

[0027] In the above sequence, the number of cycles can be determined taking into consideration the thickness of the silicon oxide film to be etched, the type of other insulating material alternately stacked, the thickness of the other insulating material, etc. While the etching process is repeated various times, the etching process can be repeated under the same conditions or under different conditions. For example, the reaction temperature and etching gas flow rate in the first cycle can be different from the reaction temperature and etching gas flow rate in the other cycles.

[0028] In one embodiment of the present invention, the etching gas may include hydrogen fluoride, an amine compound, and an inert gas.

[0029] The amine compound may include at least one compound represented by the following Chemical Formula 1: [ka] wherein R1 and R2 are each independently hydrogen or a substituted or unsubstituted aliphatic or aromatic hydrocarbon group having 1 to 12 carbon atoms (except when R1 and R2 are both hydrogen), and when the hydrocarbon group is substituted, it is substituted with nitrogen, oxygen, sulfur, phosphorus, and / or halogen atoms. R1 and R2 can be directly bonded to each other to form a ring.

[0030] In one embodiment of the present invention, the amine compound is a primary amine and / or a secondary amine, and does not include a tertiary amine.

[0031] In the present invention, the etching reaction of a silicon oxide film is a reaction that exhibits atomic layer etching (ALE) behavior. The amine compound is adsorbed onto the exposed regions of the silicon oxide film. The adsorption of the amine compound continues until the exposed regions of the silicon oxide film are substantially completely covered, i.e., until the adsorption of the amine compound onto the exposed regions of the silicon oxide film is saturated. After being adsorbed onto the surface of the silicon oxide film, the amine compound reacts with hydrogen fluoride and the silicon oxide film. The reaction of the silicon oxide film with hydrogen fluoride and the amine compound can generate reaction products such as fluorosilicate amine salts. The reaction products can be sublimated as they are generated, and therefore can be easily removed from the substrate, leaving no residue on the substrate.

[0032] The amine compound exerts different adsorption rates and chemical reactivity on the silicon oxide film surface depending on the type and size of the reactor covalently bonded to nitrogen.

[0033] FIG. 2 is a graph conceptually showing the adsorption degree of nitrogen-containing compounds, including ammonia, primary amine compounds, secondary amine compounds, and tertiary amine compounds, on the surface of a silicon oxide film, and the reactivity of these compounds with hydrogen fluoride and a silicon oxide film.

[0034] 2, from ammonia to ammonia, primary amine compounds, secondary amine compounds, and tertiary amine compounds, the degree of adsorption on the silicon oxide film surface increases, but conversely, the degree of chemical reactivity with hydrogen fluoride and silicon oxide decreases. This tendency in the degree of adsorption and reactivity of nitrogen-containing compounds may be due to molecular size. That is, as the molecular size increases from ammonia to primary amine compounds, secondary amine compounds, and tertiary amine compounds, the adsorption force due to van der Waals attraction increases, but as the molecular size decreases from ammonia to primary amine compounds, secondary amine compounds, and tertiary amine compounds, the possibility of reactivity with other molecules (hydrogen fluoride and / or silicon oxide) decreases.

[0035] The etching reaction on the surface of the silicon oxide film must be maintained in a state in which the adsorption degree of the amine compound is increased while the chemical reaction rate is not reduced. In the present invention, the region in which the adsorption of the amine compound is ensured while the chemical reaction rate is not reduced is shown as region A in the graph.

[0036] In one embodiment of the present invention, tertiary amines are not used because they are difficult to adsorb onto silicon oxide films and have a slow chemical reaction rate, and ammonia is not used because it reacts with hydrogen fluoride and silicon oxide to form by-products such as ammonium fluorosilicate, which can remain after etching.

[0037] In one embodiment of the present invention, the amine compound can include methylamine, dimethylamine, methylethylamine, ethylamine, diethylamine, propylamine, dipropylamine, butylamine, dibutylamine, tertiary butylamine, ditertiary butylamine, pyrrolidine, piperidine, piperazine, pyridine, pyrazine, etc. Some of the hydrogen atoms in the amine compound can be substituted with other atoms, such as halogen.

[0038] Primary amine compounds can include methylamine, ethylamine, propylamine, butylamine, tertiary butylamine, and the like.

[0039] The secondary amine compounds can include dimethylamine, diethylamine, di-normal propylamine, diisopropylamine, dibutylamine, di-tertiary butylamine, and the like.

[0040] The inert gas can be used as a carrier gas and can be selected from stable gases that do not react with hydrogen fluoride or amine compounds. The inert gas can be N2, He, Ne, Ar, Kr, and / or Xe. In one embodiment of the present invention, the inert gas is Ar or N2, for example, Ar. The inert gas may or may not be included in the etching gas. The ratio of the inert gas contained in the etching gas, calculated by dividing the number of moles of the inert gas by the number of moles of hydrogen fluoride, can be 0 to 100, for example, 10 or less, or 5 or less, for example, 5, 4, 3, 2, or 1.

[0041] In one embodiment of the present invention, the etching gas contains hydrogen fluoride, an amine compound, and an inert gas. However, the etching gas may also contain a substance in the form of a reaction between hydrogen fluoride and an amine compound, for example, a hydrogen fluoride salt of an amine compound.

[0042] In one embodiment of the present invention, the etching reaction of hydrogen fluoride, an amine compound, and silicon oxide can be carried out under specific conditions to exhibit atomic layer etching (ALE) behavior. For example, at least one of the reaction temperature, etching reaction time, and flow rate ratio of each component constituting the etching gas can have a specific range of values.

[0043] In one embodiment of the present invention, the reaction temperature between the silicon oxide film and the etching gas can be significantly lower than the reaction temperature when ammonia is used as the etching gas. For example, the reaction temperature between the silicon oxide film and the etching gas can be from −50° C. to 100° C. In another embodiment of the present invention, the reaction temperature can be from −30° C. to 80° C., from −30° C. to 50° C., from −30° C. to 40° C., or from −30° C. to 35° C.

[0044] The etching reaction time (e.g., the time during which the etching gas is exposed to the silicon oxide film) can be about 10 seconds to about 300 seconds, for example, 10, 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, or 300 seconds. Because the temperature of the etching reaction is relatively low, the etching reaction time can be, for example, 100 seconds or more or 200 seconds or more to ensure sufficient adsorption of the amine compound. The reaction time can also be the reaction time for each cycle when the etching reaction is repeated multiple times, or the total reaction time for all cycles.

[0045] One cycle may include a first step of self-limitingly reacting an etching gas with the exposed region of the silicon oxide film for 10 to 35 seconds, and a second step of reacting with a reaction product for 0.5 to 1 minute and then purging the remaining etching gas. In one embodiment, the first step may be performed for 10 to 23 seconds, 15 to 25 seconds, or 17 to 23 seconds, and the second step may be performed for 1 to 60 seconds, 1 to 30 seconds, or 1 to 5 seconds.

[0046] In one embodiment of the present invention, the flow ratio of the amine compound to the total etching gas may be 1% to 70%, for example, 5% to 60%, or 10% to 50%, and the relative flow ratio of hydrogen fluoride to the amine compound in the etching gas may be 0.05:1 to 1:50, or 0.1:1 to 1:30.

[0047] In one embodiment of the present invention, the pressure of the etching gas is 0.001 Torr to 10 Torr, and the partial pressure of the amine compound and hydrogen fluoride may be 0.001 or more and less than 10 Torr.

[0048] In one embodiment of the present invention, hydrogen fluoride and an amine compound may be mixed before being supplied to the reactor and then supplied to the reactor in a mixed state. However, this embodiment is not limited thereto, and hydrogen fluoride and an amine compound may be supplied to the reactor separately. For example, hydrogen fluoride and an amine compound may be supplied to the reactor sequentially. When hydrogen fluoride and an amine compound are supplied to the reactor sequentially, the supply order of each gas may be changed. When hydrogen fluoride and an amine compound are supplied to the reactor in a mixed state, the hydrogen fluoride and the amine compound may react with each other to form an amine hydrogen fluoride salt. The amine hydrogen fluoride salt may be supplied to the reactor in a gaseous state.

[0049] In one embodiment of the present invention, the silicon oxide etching process using the etching gas can be applied to various types of silicon oxide films, for example, to silicon oxide films in a stacked structure in which a silicon oxide film is stacked between other materials. In particular, when a silicon oxide film and a different material, such as a silicon nitride film, are stacked vertically, a method for etching the silicon oxide film horizontally is provided. When a silicon oxide film is present as one layer in a stacked structure, the reactive surface to be etched can correspond to the side of that layer. The method can also be applied to etching a silicon oxide film in a stacked structure in which a silicon oxide film is alternately stacked with other materials. The stacked structure according to the present invention can be distinguished from a planar structure with a broadly exposed top surface in that only the side surfaces are exposed by the etching gas.

[0050] 3A to 3D are diagrams illustrating exemplary cross sections of a stacked structure including a silicon oxide film that can be etched by an etching method according to an embodiment of the present invention.

[0051] Referring to FIG. 3A, the stacked structure may include a first layer L1 and a second layer L2 sequentially stacked on a substrate SUB and including different materials. The first layer L1 may be a silicon oxide film, and the second layer L2 may be a layer including a material other than silicon oxide. For example, the second layer L2 may be composed of an insulating material other than silicon oxide. In one embodiment of the present invention, the second layer L2 may be a layer including at least one of silicon nitride, silicon (e.g., polysilicon), SiOCN, etc. As an example, the second layer L2 may be a silicon nitride film. However, the material included in the second layer L2 is not limited thereto and may be selected from among materials having a selectivity different from that of silicon oxide with respect to the etching gas of the present invention.

[0052] The substrate SUB has a silicon oxide film disposed thereon and can be provided in various forms, such as a silicon wafer, a metal substrate, a glass substrate, or the like.

[0053] The first layer L1 may be provided on the upper surface of the substrate SUB, and the second layer L2 may be provided on the upper surface of the first layer L1. The first and second layers L1 and L2 may be provided on a plane formed by a first direction D1 and a second direction D2 that intersect with each other. For example, the first and second layers L1 and L2 may be provided along an extension direction (hereinafter, referred to as the horizontal direction) of the plane formed by the first direction D1 and the second direction D2. Figure 3A illustrates a cross section of the first and second layers L1 and L2 cut in one direction, where the first and second layers L1 and L2 extend in the second direction D2.

[0054] In one embodiment of the present invention, when an etching gas is applied to the stacked structure, the exposed side of the first layer L1 becomes a reaction region RS. The top and bottom surfaces of the first layer L1 are in contact with the second layer L2 and the substrate SUB, respectively, and are not exposed to the outside, so they cannot react with the etching gas. If a reaction occurs in the reaction region RS, the first layer L1 is etched in a second direction D2. The second layer L2 is not etched by the selective reaction of the etching gas, or if it is etched, the amount of etching is very small, so it remains intact even after etching is completed.

[0055] 3B, the laminated structure includes first and second layers L1 and L2 made of different materials, which may be alternately stacked. The first and second layers L1 and L2 may be provided on a plane defined by a first direction D1 and a second direction D2 that intersect with each other.

[0056] The first and second layers L1 and L2 may be alternately stacked in a direction perpendicular to the plane formed by the first and second directions D2, i.e., a third direction D3. The number of stacked first and second layers L1 and L2 may vary depending on the structure to be manufactured. For example, the stacked structure may vary from the simplest configuration in which one first layer L1 is provided between two second layers L2 to a configuration in which a greater number of second layers L2 are provided, for example, ten second layers L2, and the first layer L1 is provided between them.

[0057] As shown in Figures 3B and 3C, the first layer L1 and the second layer L2 may be provided with various thicknesses. For example, the first layer L1 and the second layer L2 may all have the same thickness. Alternatively, all of the first layers L1 may have the same thickness, and all of the second layers L2 may have the same thickness, with the thicknesses of the first layer L1 and the second layer L2 being different from each other. Alternatively, the thicknesses of the first layer L1 and the second layer L2 may differ from each other depending on the position. In this way, the thicknesses of the first layer L1 and the second layer L2 can be set to be different depending on the structure to be formed.

[0058] 3D, the stacked structure may include three or more layers containing different materials. For example, the stacked structure may include a first layer L1, a second layer L2, and a third layer L3, where one of the first to third layers L1, L2, and L3, e.g., the first layer L1, may include a silicon oxide film. The remaining two of the first to third layers L1, L2, and L3, i.e., the second and third layers L2 and L3, may include different materials. In one embodiment of the present invention, the second and third layers L2 and L3 may each independently include at least one of silicon nitride, polysilicon, SiOCN, etc. However, the insulating material included in the second and third layers L2 and L3 is not limited thereto.

[0059] The stacking order of the first to third layers L1, L2, and L3 can be varied in various ways. For example, if the first layer L1 and the second layer L2 are stacked in sequence, the third layer L3 may be provided on at least one of the first and second layers L1 and L2.

[0060] The silicon oxide etching according to one embodiment of the present invention will be described with reference to TSMR performed in a reactor of an etching apparatus, in which etching of a silicon oxide layer is performed.

[0061] FIG. 4 is a conceptual diagram that schematically illustrates an etching apparatus according to one embodiment of the present invention.

[0062] Referring first to FIG. 4, the etching apparatus 100 may include a reactor 20 in which the substrate 10 to be processed is accommodated, a gas supply unit 50 for supplying gas to the reactor 20, and a control unit 60 for controlling the temperature (e.g., the temperature of the stage 30), pressure, etc. within the reactor 20.

[0063] The reactor 20 accommodates the substrate 10 to be processed, provides a space in which etching of the substrate 10 to be processed is performed, and may include a stage 30 for supporting the substrate 10 to be processed therein.

[0064] The gas supply unit 50 supplies an etching gas to the reactor 20. The gas supply unit 50 may include a first gas supply unit 51 for supplying hydrogen fluoride into the reactor 20, a second gas supply unit 53 for supplying an amine compound, and a third gas supply unit 55 for supplying an inert gas. The first, second, and third gas supply units 51, 53, and 55 are each independently connected to the reactor 20 and may supply hydrogen fluoride, an amine compound, and / or an inert gas to the reactor 20. However, the type of gas supplied to the reactor 20 and the connection between the first, second, and third gas supply units 51, 53, and 55 and the reactor 20 are not limited thereto, and the reactor 20 may have one or more gas supply units. For example, the inert gas may or may not be supplied to the reactor 20. In this case, the third gas supply unit 55 for the inert gas may be connected to the reactor 20 or may be omitted. Also, at least a portion of the etching gas may be pre-mixed before being supplied to the reactor 20 and then supplied to the reactor 20 through one or more gas supply units. For example, instead of supplying hydrogen fluoride and an amine compound separately, a hydrogen fluoride salt of an amine compound may be supplied to the reactor 20 through one gas supply unit.

[0065] The reactor 20 may be provided with a gas exhaust line (not shown) for exhausting gas from the reactor 20. A vacuum pump for purging the gas to the outside may be connected to the gas exhaust line.

[0066] The control unit 60 may include additional devices such as a vacuum pumping unit (not shown) for controlling the pressure inside the reactor 20, a heating unit 40 for heating the stage 30, and a control circuit for controlling the additional devices. Here, the heating unit 40 may be provided inside the stage 30 or adjacent to the stage 30 to heat the substrate 10 to be processed. For example, the heating unit 40 may be provided inside the stage 30 and serves to set the temperature of the substrate 10 to a temperature suitable for the progress of the etching process. Alternatively, the heating unit 40 may be provided on the wall of the reactor 20 to adjust the temperature inside the reactor 20.

[0067] In one embodiment of the present invention, the control unit 60 may maintain the temperature of the stage 30 in the reactor 20 between −50° C. and 150° C. during the etching process. For example, the temperature may be maintained between −50° C. and 100° C., or between −50° C. and 30° C. In one embodiment of the present invention, the control unit 60 may also maintain the pressure in the reactor 20 between 0.001 Torr and 10 Torr. In addition, the partial pressure of the amine compound and hydrogen fluoride may be between 0.001 Torr and less than 10 Torr.

[0068] The control circuit may be configured, for example, by a computer, and may include a program, a memory, and a CPU. The program has a set of steps for performing a series of operations, and the program can adjust the temperature of the substrate, open and close the valves of the gas supply units 50, adjust the flow rates of the gases, adjust the pressure inside the reactor 20, and so on.

[0069] FIG. 5 is a flow chart showing the steps of a method for etching a silicon oxide film using the etching apparatus of FIG.

[0070] Referring to FIG. 5, an etching method according to an embodiment of the present invention may be performed in the following order: loading a substrate to be processed into a reactor of an etching apparatus (S210); setting etching conditions for performing the etching process (S220); injecting an etching gas into the reactor according to the etching conditions (S230); selectively etching a silicon oxide film (S240); and purging reaction products and etching gas from the reactor (S250).

[0071] The substrate to be processed refers to a substrate on which a silicon oxide film to be etched is formed, and may be a semiconductor substrate used in manufacturing semiconductor devices.

[0072] When the substrate to be processed is placed on the stage in the reactor, the temperature, pressure, etc. in the reactor can be adjusted by a control unit.

[0073] Then, an etching gas can be supplied into the reactor. The flow rate of the etching gas supplied into the reactor can be adjusted by a control unit. The etching gas can be supplied at a flow rate ratio that varies depending on the shape or thickness of the silicon oxide film to be etched, but can be supplied within a specific range of flow rate ratios as long as the etching reaction exhibits ALE behavior.

[0074] In one embodiment of the present invention, the flow ratio of the amine compound to the total etching gas provided in the reactor may be 1% to 70%, for example, 5% to 60%, or 10% to 50%, and the relative flow ratio of hydrogen fluoride to the amine compound in the etching gas may be 0.05:1 to 1:50, or 0.1:1 to 1:30.

[0075] In one embodiment of the present invention, the pressure of the etching gas is 0.001 Torr to 10 Torr, and the partial pressure of the amine compound and hydrogen fluoride may be 0.001 or more and less than 10 Torr.

[0076] If the flow rate ratio of hydrogen fluoride to the amine compound is outside the above range, the self-limiting effect during adsorption of the amine compound will not be achieved. If hydrogen fluoride is provided from the amine compound at a flow rate exceeding the above range, not only the silicon oxide film but also adjacent layers made of other materials will be etched, making it difficult to ensure an etching selectivity between the silicon oxide film and the adjacent materials. If the amine compound is provided from hydrogen fluoride at a flow rate exceeding the above range, the etching rate after the amine compound is adsorbed on the silicon oxide film surface may be excessively slow.

[0077] In one embodiment of the present invention, the step of selectively etching the silicon oxide layer includes reacting an etching gas with the exposed region of the silicon oxide layer in a self-limiting manner, and then removing the region where the self-limiting reaction occurred. The region where the self-limiting reaction occurred can be removed by purging the reaction products and the remaining etching gas after the reaction. In one embodiment of the present invention, the above sequence can be repeated multiple times.

[0078] The self-limiting reaction is initiated by the adsorption of the etching gas onto the exposed surface of the silicon oxide film. In particular, the amine compound can react with the silicon oxide film and hydrogen fluoride after adsorption onto the surface of the silicon oxide film. The reactant can be sublimated as it is produced and purged along with the remaining etching gas. The self-limiting reaction can be carried out for 10 to 30 seconds, and the reaction product and the remaining etching gas can be removed by purging for 0.5 to 1 minute.

[0079] The sequence of injecting an etching gas into a reactor, selectively removing the silicon oxide film using a self-limiting reaction, and purging the remaining reaction products and etching gas can be repeated N times (N is an integer equal to or greater than 0) depending on the thickness of the silicon oxide film to be etched, etc. In one embodiment, the sequence can be repeated at least one time.

[0080] In one embodiment of the present invention, the reaction between a silicon oxide film, hydrogen fluoride, and an amine compound exhibits atomic layer etch (ALE) behavior. The reaction is initiated by the adsorption of the amine compound onto the exposed surface of the silicon oxide film, and the progress of the reaction can be determined depending on the shape and area of ​​the exposed silicon oxide film. However, in one embodiment of the present invention, the top surface of the silicon oxide film is not entirely exposed to the outside, but rather the side surfaces of the silicon oxide film are exposed to the outside. Because the side surfaces of the silicon oxide film have a much smaller area than the top surface of the silicon oxide film, the etching reaction rate of the silicon oxide film decreases when the amine compound is completely adsorbed onto the side surfaces of the silicon oxide film and becomes saturated. The adsorption rate and reaction rate with the silicon oxide film may vary depending on the type of amine compound adsorbed. In addition, because the etching reaction exhibits ALE behavior, the silicon oxide film layer can be etched atomically over N cycles, making it very easy to etch to a desired level (e.g., a predetermined depth). That is, in one embodiment of the present invention, the amount of etching of the silicon oxide film can be precisely controlled.

[0081] The etching method according to an embodiment of the present invention uses hydrogen fluoride and an amine compound as etching gases to etch a silicon oxide film at a high etching selectivity relative to other materials (e.g., silicon nitride film) while reducing etching by-products. Therefore, the high etching selectivity relative to other materials (e.g., silicon nitride film) prevents problems caused by simultaneous etching of other materials.

[0082] Furthermore, since the silicon oxide film etching rate is faster than in processes using hydrogen fluoride and ammonia as etching gases, there is no need to heat the substrate to increase the reaction rate. Furthermore, the reaction product of hydrogen fluoride and ammonia, i.e., ammonium fluorosilicate, which is generated as a by-product in processes using hydrogen fluoride and ammonia as etching gases, is not generated, and therefore defects caused by the by-product are not generated. In particular, the process of post-treating the substrate to remove the by-product of the reaction of ammonia and hydrogen fluoride (e.g., a post-heating process) can be omitted. The post-treatment process has the problem of exposing the substrate to high temperatures, which can change the amount of silicon oxide film etched and reduce the etching selectivity relative to other materials. However, by eliminating the post-treatment process, these problems can be solved.

[0083] A method for etching a silicon oxide film by providing an etching gas to the silicon oxide film using an etching apparatus according to an embodiment of the present invention exhibits high selectivity relative to adjacent layers made of other materials, such as silicon nitride, and is particularly applicable to fine structures in which the silicon oxide film has a thickness and line width of 10 nm or less.

[0084] In one embodiment of the present invention, the use of a secondary or lower amine compound, i.e., a primary amine and / or a secondary amine compound, enables selective etching of silicon oxide at a relatively lower temperature and higher pressure than when a tertiary amine is used. Above all, in one embodiment of the present invention, the use of an etching gas containing a secondary or lower amine compound enables selective etching of silicon oxide from other materials (e.g., polysilicon, silicon nitride, SiOCN, etc.).

[0085] In one embodiment of the present invention, the use of secondary or lower amines, i.e., primary and / or secondary amines, allows for selective etching of silicon oxide at relatively lower temperatures and higher pressures than when using tertiary amines.

[0086] The above-described method for selectively etching a silicon oxide film stack structure can be used in the manufacturing process of various semiconductor devices.

[0087] For example, in a NAND flash memory device manufacturing process, an oxide film grown in an isolation region is etched before forming an ONO (Oxide-Nitride-Oxide) insulating film and a control gate layer on the floating gate. In this case, if the amount of oxide film etching is not precisely controlled, the degree of exposure of the floating gate layer varies from device region to device region, resulting in non-uniform inter-device characteristics. Furthermore, if the oxide film is not selectively removed, the exposed floating gate electrode may be co-etched during etching. A stacked structure etching method according to an embodiment of the present invention can achieve high etching selectivity and high etching efficiency when etching a silicon oxide film. Furthermore, the method for selectively etching a silicon oxide stacked structure can also be applied to processes such as removing a mold oxide film after forming a lower electrode of a cylindrical capacitor in a memory device manufacturing process, and selectively removing a silicon oxide film using a silicon nitride film as an etching barrier when forming an air gap for insulation between metal wirings.

[0088] The above-described semiconductor device manufacturing process is merely exemplary, and the method for selectively etching a silicon oxide film stack structure can be applied to various other semiconductor device manufacturing processes without departing from the concept of the present invention.

[0089] Although the present invention has been described above with reference to preferred embodiments, it will be understood by those skilled in the art or those having ordinary knowledge in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

[0090] Experimental Example A - Etching behavior on a flat substrate Experimental Example A-1. Silicon oxide film etching behavior depending on etching gas type and time After preparing a flat substrate with a silicon oxide film formed on its top surface, the etching rate of the silicon oxide film was compared using various nitrogen-containing compounds. More specifically, an etching gas containing a nitrogen-containing compound, hydrofluoric acid, and an inert gas was used, and the nitrogen-containing compounds used were ammonia, a secondary amine, and a tertiary amine. Dimethylamine (DMA) was used as the secondary amine, and trimethylamine (TMA) was used as the tertiary amine.

[0091] The degree of etching of the silicon oxide film according to each etching gas was measured as a function of the temperature and time on a flat substrate. The evaluation conditions are shown in Table 1 below. The times in Table 1 correspond to either a 20-second etching reaction followed by a 10-second purge cycle repeated five times, or a 100-second etching reaction followed by a 60-second purge. The temperatures shown below indicate the stage temperature, and the sidewall temperature was maintained at 80°C.

[0092] [Table 1] FIG. 6 is a graph showing the etching rate of a silicon oxide film as a function of time when the stage temperature is 035° C. and the pressure in the reactor is 3 Torr.

[0093] Referring to Figure 6, under these conditions, ammonia etched little or no silicon oxide film, regardless of the passage of time. In contrast, dimethylamine and trimethylamine, which correspond to secondary and tertiary amines, exhibited varying degrees of etching reaction over time. Dimethylamine and trimethylamine exhibited the highest etching rate after 20 seconds of application, and exhibited a lower etching rate after 60 seconds than after 20 seconds. After application of the etching gas, the reaction with the silicon oxide film increased for a certain time (e.g., between about 10 and about 30 seconds), but decreased after about 30 seconds, indicating that dimethylamine and trimethylamine undergo a self-limiting reaction with the silicon oxide film surface.

[0094] Furthermore, the etching rate of silicon oxide film by dimethylamine is approximately twice as high as that by trimethylamine, confirming that the etching reaction efficiency of silicon oxide film by dimethylamine is very high.

[0095] Experimental Example A-2. Silicon oxide film etching behavior depending on etching target, etching gas type, and temperature After preparing a flat substrate with a film to be etched on its upper surface, the amount of etching of the target was confirmed depending on the temperature by changing the type of nitrogen-containing compound. The target films to be etched were SiO2 film, SiN film, Si film, SiOCN film, and SRO (Si-enriched oxide) film, and the etching reaction was carried out at 35°C, 60°C, and 120°C. Here, the remaining conditions except for the target and temperature were maintained the same as in Experimental Example A-1.

[0096] Table 2 below shows the etching amount of the etching target depending on the temperature, and Table 3 below shows the etching ratio for the etching target. Figures 7A to 7C are graphs showing the etching amount of the etching target depending on the temperature, along with the etching selectivity of specific etching targets. The etching selectivity is shown for SiO2 / SiN and SiO2 / Si.

[0097] [Table 2]

[0098] [Table 3] 7A to 7C, in the case of ammonia, virtually no reaction occurred in all types of etching targets tested, and therefore the etching amount was very small. Although not shown in the table, in the case of ammonia, even when provided to the etching target at a relatively high temperature and pressure (120°C, 9 Torr), no etching reaction was observed, and it was confirmed that virtually no etching reaction occurred, or even if it did occur, it was very small.

[0099] Dimethylamine and trimethylamine each increased the amount of SiO2 etched as the temperature increased, but in the case of trimethylamine, the amount of SiO2 etched became excessively large when the temperature exceeded 100°C, making it difficult to adjust the amount of etching to the desired level.

[0100] Dimethylamine etched silicon oxide film at temperatures below 100°C, for example, at all temperatures tested, 35°C and 60°C, approximately twice or more than twice that of trimethylamine. In the case of dimethylamine, although the etching rate of silicon oxide film was more than twice that of trimethylamine, the etching rates of other etching targets (SiN and Si) were at the same level as or even less than those of trimethylamine.

[0101] Looking at the etching selectivity, the etching selectivity of silicon oxide film to silicon nitride film (SiO2 / SiN) was 29 for trimethylamine at 35°C, but 54 for dimethylamine, and 14 for trimethylamine at 60°C, but 72 for dimethylamine. Thus, the etching selectivity of dimethylamine was significantly higher than that of trimethylamine.

[0102] Experimental Example A-3. Silicon oxide film etching behavior when HF is used alone as the etching gas After preparing a flat substrate with a film to be etched formed on its surface, hydrogen fluoride was used as the etching gas to check the amount of etching of the film to be etched depending on the temperature. The remaining conditions, except for the etching gas, were the same as those in Experimental Example A-1.

[0103] FIG. 8 is a graph showing the amount of etching of an object to be etched depending on the temperature when hydrogen fluoride is used as the etching gas.

[0104] 8, when hydrogen fluoride is used as an etching gas, the etching rates of silicon oxide, silicon nitride, and silicon are slow, and the SiO2 / SiN selectivity is also low. It was further confirmed that as the temperature increases, the surface adsorption of hydrogen fluoride in the gas phase is inhibited, resulting in a decrease in the etching rate for all film types.

[0105] Experimental Example B. Etching behavior in a laminated structure Experimental Example B-1. Etching behavior of different amine compounds in a laminated structure After fabricating a stacked structure with alternating oxide and silicon nitride films, the etching amount of the silicon oxide film was confirmed using primary amine, secondary amine, and tertiary amine as etching gases. The primary amine used was monomethylamine (MMA), the secondary amine used was dimethylamine (DMA), and the tertiary amines used were trimethylamine (TMA) and N,N-dimethylethylamine (DMEA).

[0106] In this experimental example, the flow rates of the amine compound, hydrogen fluoride, and argon were 40 sccm, 40 sccm, and 35 sccm, respectively. The reactor pressure was 3 Torr, and the stage temperature was 30°C. The reaction time was 20 seconds per reaction, and the reaction was repeated five times. The purge time for each reaction was 10 seconds or more. In this experimental example, a stacked structure was fabricated as shown in FIG. 9, with a silicon oxide film as the first layer and a silicon nitride film as the second layer. The etching depth was measured as the distance EA from the edge of the stacked structure to the side of the remaining silicon oxide film after etching, as shown in FIG. 9.

[0107] FIG. 10 is a graph showing the etching amount for each amine compound.

[0108] 10, when a silicon oxide film was etched using an etching gas containing monomethylamine and dimethylamine, the etching depth was 5 nm or more, whereas when trimethylamine and dimethylethanolamine were used, the etching depth was 3 nm or less. Here, although not shown, when a silicon oxide film was etched using an etching gas containing monomethylamine and dimethylamine, the etching depth of a silicon nitride film was less than 0.1 nm.

[0109] Experimental Example B-2. Etching behavior of tertiary amine compounds in laminated structures After fabricating a stacked structure with alternating oxide and silicon nitride layers, the etching amount of the silicon oxide layer was confirmed using a tertiary amine (trimethylamine) as the etching gas. In this experiment, the flow rates of the amine compound, hydrogen fluoride, and argon were 40 sccm, 40 sccm, and 35 sccm, respectively, the reactor pressure was 3 Torr, and the stage temperature was 30°C. The reaction time was 20 seconds per run, and the run was repeated five times. In this experiment, the stacked structure was fabricated in the form shown in Figure 3B, with a silicon oxide layer as the first layer and a silicon nitride layer as the second layer.

[0110] 11 is an SEM image showing a cross section of the stacked structure after etching. As shown in the image, when etching was performed at a relatively low temperature of 30°C using an etching gas containing trimethylamine, reaction by-products were found to be deposited on the sidewalls of the stacked structure.

[0111] Experimental Example B-3. Etching behavior according to pressure in a laminated structure After fabricating a stacked structure (as shown in Figure 3B) in which silicon oxide and silicon nitride films were alternately stacked, secondary amine (dimethylamine) and tertiary amine (trimethylamine) were used as etching gases to confirm the etching amount as a function of pressure and critical dimension (CD). The silicon nitride films were fabricated to a thickness of 20 nm each. In this experiment, as in Experiments B-1 and B-2, the reaction time was 20 seconds per run, and the test was repeated five times.

[0112] Table 4 shows the etching amount when etching was performed using dimethylamine, and Table 5 shows the etching amount when etching was performed using trimethylamine. The values ​​in Tables 4 and 5 were measured for the portion of the stacked structure shown in FIG. 12. In FIG. 12, the first layer corresponds to a silicon oxide film, and the second layer corresponds to a silicon nitride film. TH is the stacked thickness of the silicon oxide film, EA is the etching amount in the horizontal direction from the side of the silicon oxide film before etching, CDs is the thickness at the side of the silicon oxide film when it is etched, and CDe is the inner thickness furthest from the side of the silicon oxide film when it is etched.

[0113] In this experimental example, all conditions were maintained the same except for the pressure in the reactor and the type of amine compound. Here, the stacked structure was fabricated in the form shown in Figure 3B. A silicon oxide film was used as the first layer, and a silicon nitride film was used as the second layer, and the thickness TH of the silicon oxide film was fabricated to have a gradually decreasing value.

[0114] [Table 4]

[0115] [Table 5] *UM: Layer collapse due to over-etching was observed, and the amount of etching could not be measured. FIG. 13 is a cross-sectional SEM image showing the amount of etching when etching is performed using dimethylamine and trimethylamine, respectively.

[0116] Referring to Tables 4, 5, and FIG. 12, when trimethylamine, a tertiary amine, was included in the etching gas, the etching reaction of the silicon oxide film hardly occurred at relatively low pressures of 0.5 Torr and 1 Torr, and it was impossible to measure the etching amount of the silicon oxide film. At high pressures of 3 Torr or higher, the etching reaction of the silicon oxide film occurred. However, when trimethylamine was included in the etching gas, the etching rate of the silicon nitride film also increased as the pressure increased, and collapse of the silicon nitride film layer was observed.

[0117] In contrast, when the etching gas contained dimethylamine, a secondary amine, the etching reaction of silicon oxide film occurred stably not only at low pressure but also at high pressure. Furthermore, the silicon nitride film was etched at a significantly lower rate than the silicon oxide film at both low and high pressures. From these results, it can be interpreted that when dimethylamine is used as the etching gas, a stable selectivity for silicon nitride film and silicon oxide film can be obtained regardless of the etching gas pressure in the reactor.

[0118] Furthermore, the CDs-CDe value can be 0 or close to 0 when the silicon oxide layer is etched inward or when the silicon oxide layer is etched cleanly without leaving any reaction residues against the silicon nitride layer. The CDs-CDe value increases when reaction residues remain or the silicon oxide layer is not completely etched. Tables 4 and 5 show that for dimethylamine, the CDs-CDe value is generally small without any correlation with pressure, whereas for trimethylamine, the CDs-CDe value increases significantly as the pressure increases. This means that when the reactor pressure is high, the silicon oxide layer is not etched cleanly and a large amount of residue remains.

[0119] 14A and 14B are graphs showing the etching behavior as a function of pressure when the silicon oxide film is 10 nm thick. The graphs in FIGS. 14A and 14B are diagrams of the data in Tables 4 and 5. In the case of trimethylamine, it can be seen that as the pressure increases, the silicon nitride film collapses, making it difficult to detect the etching amount.

[0120] Experimental Example B-4. Etching selectivity depending on the flow rate ratio of secondary amine compounds in a laminated structure The etching amount of silicon oxide film and silicon nitride film was confirmed by varying the flow rate of the etching gas supplied to the reactor, with the flow rate of argon as an inert gas fixed (35 sccm) and the flow rate ratio of dimethylamine, a secondary amine compound, and hydrofluoric acid. In this experimental example, the remaining conditions except for the flow rate ratio of dimethylamine and hydrofluoric acid were maintained substantially the same as in Experimental Example B-2.

[0121] Table 6 below shows the etching amounts of silicon oxide films and silicon nitride films according to the flow rate ratio of dimethylamine and hydrofluoric acid.

[0122] [Table 6] Referring to Table 6, when the flow ratio of hydrogen fluoride to dimethylamine is 8:1, the selectivity reaches 10, and when the flow ratio is 1:1 or 1:10, the silicon nitride film is hardly etched, resulting in a very high selectivity. However, when the flow ratio of hydrogen fluoride is 1:50, it is difficult for hydrogen fluoride to react with the silicon nitride film, and etching does not occur.

[0123] Experimental Example B-5. Etching behavior depending on amine compound and etching reaction time in a laminated structure When etching a silicon oxide film using an etching gas containing a secondary amine compound, dimethylamine, and a tertiary amine compound, trimethylamine, the etching amount was measured by varying the etching reaction time. Table 6 below shows the etching results for reaction times of 100 seconds and 200 seconds for etching gases containing dimethylamine and etching gases containing trimethylamine, where the flow rates of the amine compound, hydrogen fluoride, and argon were 40 sccm, 40 sccm, and 35 sccm, respectively, the reactor pressure was 1 Torr, and the stage temperature was 60°C. Figure 15 shows SEM cross-sectional images of the etching results in Table 7 as a function of reaction time and amine compound.

[0124] [Table 7] Referring to Table 7 and FIG. 15, it can be seen that under a relatively low pressure of 1 Torr, when an etching gas containing trimethylamine, a tertiary amine compound, is used, etching hardly occurs regardless of reaction time.

[0125] 1. Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art or those with ordinary knowledge in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

[0126] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims. [Explanation of symbols]

[0127] 100 Etching equipment 10. Substrate to be processed 20 Reactor 30 stages 40 Heating section 50 Gas supply unit 60 Control Unit

Claims

1. A method for dry etching a silicon oxide film, comprising: a step of reacting an etching gas containing hydrogen fluoride, an amine compound, and an inert gas with a stacked structure including a first layer including a silicon oxide film and a second layer including a material different from the silicon oxide film and stacked on the first layer, thereby selectively etching the first layer; the etching step includes reacting the etching gas with the exposed area of ​​the first layer in a self-limiting manner; and removing the self-limiting reacted area; The amine compound includes at least one compound represented by the following chemical formula: 【Chemistry 1】 Here, R １ and R ２ are each independently hydrogen or a substituted or unsubstituted aliphatic or aromatic hydrocarbon group having 1 to 12 carbon atoms (R １ and R ２ and (except when) are simultaneously hydrogen, and the substituted aliphatic or aromatic hydrocarbon group is substituted with nitrogen, oxygen, sulfur, phosphorus, and / or halogen atoms.

2. 2. The method of claim 1, wherein the etching step is repeated a plurality of times.

3. 3. The method of claim 2, wherein when the etching step is repeated in a plurality of cycles, one cycle includes reacting the etching gas with the exposed region of the first layer in a self-limiting manner, and purging the reaction products and remaining etching gas after the reaction.

4. 2. The method for dry etching a silicon oxide film according to claim 1, wherein the second layer includes one of a silicon nitride film, a silicon film, and a SiOCN film.

5. 5. The method for dry etching a silicon oxide film according to claim 4, wherein the second layer is a silicon nitride film.

6. 2. The method of claim 1, wherein the etching is performed at a temperature of -50° C. to 150° C.

7. 7. The method of claim 6, wherein the etching gas is applied to the exposed area of ​​the silicon oxide film for a period of 10 to 30 seconds.

8. 8. The method for dry etching a silicon oxide film according to claim 7, wherein the etching gas is supplied into a reactor that accommodates the substrate to be processed on which the silicon oxide film is formed, and the pressure of the etching gas in the reactor is 0.001 Torr to 10 Torr.

9. 2. The method for dry etching a silicon oxide film according to claim 1, wherein a flow ratio of said hydrogen fluoride to said amine compound is 0.05:1 to 1:

30.

10. 2. The method for dry etching a silicon oxide film according to claim 1, wherein the amine compound is at least one of methylamine, dimethylamine, methylethylamine, ethylamine, diethylamine, propylamine, dipropylamine, butylamine, dibutylamine, tertiary butylamine, ditertiary butylamine, pyrrolidine, piperidine, piperazine, pyridine, and pyrazine.

11. 11. The method for dry etching a silicon oxide film according to claim 10, wherein the amine compound is at least one of dimethylamine, diethylamine, di-normal-propylamine, diisopropylamine, dibutylamine, and di-tertiary-butylamine.

12. 2. The method of dry etching a silicon oxide film according to claim 1, wherein the hydrogen fluoride and the amine compound are supplied sequentially when the etching gas is supplied to the stacked structure.

13. 2. The method for dry etching a silicon oxide film according to claim 1, wherein when the etching gas is supplied to the stacked structure, the hydrogen fluoride and the amine compound are mixed first, and then the mixed gas is supplied to the stacked structure.

14. 2. The silicon oxide film dry etching method according to claim 1, wherein a plurality of the first layer and a plurality of the second layer are provided and are alternately stacked.

15. 2. The method for dry etching a silicon oxide film according to claim 1, further comprising a third layer provided on at least one of the first and second layers and containing a material different from that of the first and second layers.

16. A method for dry etching a silicon oxide film, comprising: a dry etching step of removing the silicon oxide film by reacting an etching gas containing hydrogen fluoride, an amine compound represented by the following chemical formula, and an inert gas with the silicon oxide film, The dry etching step includes a step of reacting the etching gas with the exposed region of the silicon oxide film in a self-limiting manner, and removing the self-limiting reacted region. 【Chemistry 2】 Here, R １ and R ２ are each independently hydrogen or a substituted or unsubstituted aliphatic or aromatic hydrocarbon group having 1 to 12 carbon atoms (R １ and R ２ and (except when) are simultaneously hydrogen, and the substituted aliphatic or aromatic hydrocarbon group is substituted with nitrogen, oxygen, sulfur, phosphorus, and / or halogen atoms.

17. 17. The method of claim 16, wherein the dry etching is performed at a temperature of −50° C. to 150° C., and the etching gas is applied to the exposed region of the silicon oxide layer for 0 to 30 seconds.

18. 18. The method of claim 17, wherein the hydrogen fluoride and the amine compound are provided to the exposed region of the silicon oxide layer at a flow ratio of 0.05:1 to 1:

30.

19. a step of selectively dry-etching the silicon oxide film by reacting an etching gas containing hydrogen fluoride, an amine compound represented by the following Chemical Formula 3, and an inert gas with a semiconductor substrate having a stacked structure in which silicon oxide films and silicon nitride films are alternately stacked in a first direction, The selective dry etching step includes a step of reacting the etching gas with the exposed region of the silicon oxide film in a self-limiting manner and removing the self-limiting reacted region. 【Transformation 3】 Here, R １ and R ２ are each independently hydrogen or a substituted or unsubstituted aliphatic or aromatic hydrocarbon group having 1 to 12 carbon atoms (R １ and R ２ and (except when) are simultaneously hydrogen, and the substituted aliphatic or aromatic hydrocarbon group is substituted with nitrogen, oxygen, sulfur, phosphorus, and / or halogen atoms.

20. 20. The method of claim 19, wherein the dry etching is performed at a temperature of −50° C. to 100° C., the etching gas is provided to the exposed region of the silicon oxide layer for 10 to 30 seconds, and a flow ratio of the hydrogen fluoride to the amine compound is 0.05:1 to 1:30.

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