Thin film etching method

Abstract

A thin film etching method according to one aspect of the present invention comprises: a preparation step of preparing a substrate on which a pattern including a nitride film is formed; a surface treatment step of treating the surface of the nitride film with an oxygen-containing gas to oxidize at least a portion thereof; and an etching step for supplying an etching gas onto the oxide layer in order to remove at least a portion of the oxide layer on the nitride film surface oxidized by the surface treatment step, in which the surface treatment step and the etching step are periodically repeated.

Description

Technical Field

[0001] The present invention relates to semiconductor manufacturing, and more particularly to a thin film etching method. Background Art

[0002] In order to manufacture semiconductor elements, various processes are performed on a substrate processing device in a vacuum atmosphere. For example, a process of loading a substrate in a process chamber and depositing or etching a thin film on the substrate can be performed. The substrate is supported by a substrate support portion disposed in the process chamber, and a process gas can be sprayed onto the substrate by a gas spray portion disposed on the upper portion of the substrate support portion to process the substrate.

[0003] On the other hand, when one or more thin film patterns are formed on a substrate, a plurality of thin films may be exposed on the substrate. For example, insulating films such as oxide films and nitride films may be exposed on the substrate. Afterwards, a process of selectively etching one of these insulating films may be added. Recently, due to the high integration of semiconductor devices, the thickness of these insulating films has become thinner, and there is a problem of etching unwanted insulating films due to insufficient selectivity in the etching step of these insulating films.

[0004] In addition, when the thickness of the insulating film is reduced, the penetration of the etching solution becomes difficult, which limits the conventional wet etching. Although dry etching using a halide-based etching gas is being studied, there is a problem that the etching selectivity is not high. Summary of the invention

[0005] Technical issues to be solved

[0006] The present invention is used to solve various problems including the above problems, and its purpose is to provide a thin film etching method, which uses dry etching with a higher etching selectivity ratio when manufacturing highly integrated semiconductor components. However, these are only exemplary, and the scope of the present invention is not limited thereto.

[0007] Means of solving the problem

[0008] A thin film etching method as one aspect of the present invention for solving the above-mentioned problem is characterized in that it includes the following steps: a preparation step of preparing a substrate on which a pattern including a nitride film is formed; a surface treatment step of treating the surface of the nitride film with an oxygen-containing gas to oxidize at least a portion of it; and an etching step of supplying an etching gas to the oxide layer in order to remove at least a portion of the oxide layer on the surface of the nitride film oxidized by the surface treatment step, wherein the surface treatment step and the etching step are periodically repeated.

[0009] Another aspect of the thin film etching method of the present invention for solving the above-mentioned problem is characterized in that it includes the following steps: a preparation step of preparing a substrate on which a pattern including an oxide film and a nitride film is formed; a surface treatment step of treating the surfaces of the oxide film and the nitride film with an oxygen-containing gas to oxidize at least a portion of them; and an etching step of supplying an etching gas to the oxide layer in order to remove at least a portion of the oxide layer on the surface of the nitride film oxidized by the surface treatment step, wherein the surface treatment step and the etching step are periodically repeated.

[0010] In the surface treatment step of the thin film etching method, the oxide layer formed on the oxide film and the oxide layer formed on the nitride film have different physical properties from each other.

[0011] In the etching step of the thin film etching method, etching ratios of an oxide layer formed on the oxide film and an oxide layer formed on the nitride film are different from each other.

[0012] In the thin film etching method, an etching rate of an oxide layer formed on the nitride film may be greater than an etching rate of an oxide layer formed on the oxide film.

[0013] In the thin film etching method, the oxygen-containing gas may include at least one of O2, O3, H2O, H2O2 and N2O.

[0014] In the thin film etching method, the etching gas may be a mixed gas of NH 3 and NF 3 or a halide-based gas.

[0015] In the thin film etching method, the surface treatment step may be performed in a plasma atmosphere.

[0016] Effects of the Invention

[0017] According to some embodiments of the present invention, the thin film etching method can be used to embody a thin film etching method using dry etching with a higher etching selectivity when manufacturing highly integrated semiconductor devices. Of course, the scope of the present invention is not limited by these effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a sequence diagram showing a thin film etching method according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram showing a thin film etching method according to an embodiment of the present invention.

[0020] Figure 3This is a graph showing the thickness of the oxide layer on the surface of the nitride film oxidized in the surface treatment step and the thickness of the nitride film in a thin film etching method according to one embodiment of the present invention, while repeatedly performing a unit cycle consisting of a surface treatment step and an etching step, and measuring the thickness of the oxide layer on the surface of the nitride film oxidized in the surface treatment step.

[0021] Figures 4 to 5 1 is a schematic cross-sectional view of a substrate illustrating a thin film etching method according to some embodiments of the present invention.

[0022] Figure 6 and Figure 7 The graphs show the results of measuring line widths in a stacked structure to which a thin film etching method according to some embodiments of the present invention is applied.

[0023] Figure 8 It is a comprehensive Figure 6 and Figure 7 A graph of the measurement results.

[0024] Fig. 9 This is a graph showing in-situ monitoring of the etched thickness based on the etching time when the thin film etching method according to one embodiment of the present invention is applied.

[0025] Fig.10 : is a graph showing the result of calculating the amount of fluorine (F) atoms adsorbed to the surface of a thin film during execution of the thin film etching method according to one embodiment of the present invention.

[0026] Fig.11 This is a graph comparing the etching thickness of silicon oxide film (SiO2) and silicon nitride film (SiN) based on the process temperature.

[0027] Fig.12 This is a graph showing RGA intensity of components of an etchant analyzed in a thin film etching method according to an embodiment of the present invention.

[0028] Fig.13 FIG. 1 is a schematic diagram showing a substrate processing apparatus for explaining a thin film etching method according to some embodiments of the present invention.

[0029] Fig.14 This is a schematic diagram showing that a plurality of fluorine anions form a fluorine complex in the thin film etching method according to an embodiment of the present invention.

[0030] Fig.15 This is a graph showing the etching rate and etching selectivity based on the Ar flow rate in the thin film etching method according to the embodiment of the present invention.

[0031] Fig.16 This is a graph showing the etching rate depending on the Ar flow rate in the thin film etching method of the comparative example. DETAILED DESCRIPTION

[0032] Several preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] The embodiments of the present invention are intended to more completely explain the embodiments of the present invention to those of ordinary skill in the technical field of the present invention, and the following embodiments may be changed into a variety of different forms, and the scope of the present invention is not limited thereto. On the contrary, these embodiments are provided to make the present invention more substantial and complete, and to fully convey the ideas of the present invention to those of ordinary skill in the technical field of the present invention. In addition, for the convenience and accuracy of the description, the thickness or size of each layer in the drawings is exaggerated.

[0034] Figure 1 is a sequence diagram showing a thin film etching method according to an embodiment of the present invention, Figure 2 This is a schematic diagram showing a thin film etching method according to an embodiment of the present invention.

[0035] Reference Figure 1 and Figure 2 A thin film etching method according to an embodiment of the present invention comprises the following steps: a preparation step S10, preparing a substrate on which a pattern including a nitride film 55 is formed; a surface treatment step S20, treating the exposed surface of the nitride film 55 with an oxygen-containing gas to oxidize at least a portion of the surface; and an etching step S30, supplying an etching gas to the oxide layer 51 in order to remove at least a portion of the oxide layer 51 on the surface of the nitride film oxidized by the surface treatment step, wherein the surface treatment step S20 and the etching step S30 are repeatedly performed periodically at least once.

[0036] In the surface treatment step S20, the oxygen-containing gas may include at least one of O2, O3, H2O, H2O2 and N2O, and the surface treatment step may be performed in a plasma atmosphere or a thermal atmosphere.

[0037] In the etching step S30, the etching gas may be a mixed gas of NH3 and NF3 or a halide-based gas.

[0038] Figure 3 This is a graph showing the thickness (●) of the oxide layer (Oxidation Layer) 51 on the surface of the nitride film oxidized by the surface treatment step and the thickness (○) of the nitride film (SiN) by repeatedly performing a unit cycle consisting of the surface treatment step S20 and the etching step S30 in a thin film etching method according to an embodiment of the present invention. The thickness (○) of the nitride film (SiN) can be understood as the thickness taking into account both the thickness of the pure silicon nitride film 55 and the thickness of the oxide layer 51 on the surface of the nitride film. Figure 3 Among the steps shown, the step indicated by "oxidation" corresponds to the above-mentioned surface treatment step S20, and the step indicated by "etching" corresponds to the above-mentioned etching step S30.

[0039] Reference Figures 1 to 3 During the execution of the unit cycle, the thickness of the oxide layer 51 on the surface of the nitride film oxidized by the surface treatment step is increased from the initial Gradually increase to about During the etching step, the thickness of the oxide layer 51 gradually decreases by about Therefore, it can be confirmed that the oxide layer (Oxidation Layer) 51 on the surface of the nitride film is etched by the etching step and the thickness of the nitride film is gradually reduced by about This unit cycle is repeated 8 times, and the thickness of the nitride film increases from about Gradually reduce to

[0040] According to the thin film etching method, a portion of the surface of the nitride film 55 is oxidized, and the oxidized unstable oxide layer 51 can be removed by using the atomic layer removal (ALR) process. This method has the advantage of being applicable to a self-limiting process (Self Limitation Process) and can use dry source materials frequently used in semiconductor mass production processes, thus facilitating mass production applicability.

[0041] In addition, when the above-mentioned thin film etching method is applied to a substrate on which a pattern including an oxide film and a nitride film is formed, it is estimated that the utilization rate is relatively high because the etching selectivity ratio of the oxide film and the nitride film is somewhat different. The following describes a process of applying the above-mentioned thin film etching method to a substrate on which a pattern including an oxide film and a nitride film is formed.

[0042] Figures 4 to 5 1 is a schematic cross-sectional view of a substrate illustrating a thin film etching method according to some embodiments of the present invention. Figure 4 2 shows a state before performing etching step S30 in the thin film etching method of some embodiments of the present invention, Figure 5 The state after the etching step S30 is performed is shown.

[0043] Reference Figures 1 to 5 The thin film etching method of some embodiments of the present invention includes the following steps: a preparation step S10, preparing a substrate S on which a pattern 56 including an oxide film 54 and a nitride film 55 is formed; a surface treatment step S20, treating the surfaces of the oxide film 54 and the nitride film 55 exposed in the pattern 56 with an oxygen-containing gas to oxidize at least a portion of them; and an etching step S30, supplying an etching gas to the oxide layer 51 in order to remove at least a portion of the oxide layer 51 on the surface of the nitride film oxidized by the surface treatment step, wherein the surface treatment step and the etching step are repeatedly performed periodically at least once.

[0044] In the surface treatment step S20, the oxygen-containing gas may include at least one of O2, O3, H2O, H2O2 and N2O, and the surface treatment step may be performed in a plasma atmosphere.

[0045] In the etching step S30, the etching gas may be a mixed gas of NH3 and NF3 or a halide-based gas.

[0046] In the surface treatment step S20, the physical properties of the oxide layer formed on the oxide film 54 and the oxide layer formed on the nitride film 55 are different from each other. Therefore, in the etching step S30, the etching ratios of the oxide layer formed on the oxide film 54 and the oxide layer formed on the nitride film 55 are different from each other. For example, the etching rate of the oxide layer formed on the nitride film 55 may be greater than the etching rate of the oxide layer formed on the oxide film 54. In the surface treatment step S20, both oxygen radicals and nitrogen radicals exist in the oxide layer 51 formed on the surface of the nitride film 55. In this case, it is relatively easier to react with fluorine (F) in the subsequent etching step S30.

[0047] In addition, in the surface treatment step S20, the physical properties of the oxide layer formed on the nitride film 55 are different from the physical properties of the oxide film 54. For example, the oxide film 54 is deposited at a process temperature of about 500 to 600° C., while the oxide layer formed on the nitride film 55 in the surface treatment step S20 is formed at a low temperature of about 150 to 250° C., so the difference in film quality will be very obvious.

[0048] like Figure 5 As shown, when the above-mentioned thin film etching method is applied to the stacked pattern 56 of the stacked oxide film 54 and the nitride film 55 , the oxide film 54 is hardly etched, and the nitride film 55 is etched more than the oxide film 54 .

[0049] Figure 6 and Figure 7 1 is a diagram showing the results of measuring line width in a stacked structure to which a thin film etching method according to some embodiments of the present invention is applied, Figure 8 It is a comprehensive Figure 6 and Figure 7 A graph of the measurement results.

[0050] Specifically, Figure 6 10 shows the results before the etching step S30 is applied in the thin film etching method of some embodiments of the present invention, Figure 7 The results after applying the etching step S30 in the thin film etching method according to some embodiments of the present invention are shown. Figure 8The numbers appearing on the horizontal axis of sequentially show the numbering of the ordered pairs of silicon oxide film (SiO2) and silicon nitride film (SiN) starting from the top in a thin film structure in which silicon nitride film (SiN) and silicon oxide film (SiO2) are alternately stacked.

[0051] Reference Figure 6 and Figure 7 The spacing between each unit film is measured in a thin film structure in which silicon nitride film (SiN) and silicon oxide film (SiO2) are alternately stacked. The trench space having the spacing is filled with a conductive material to form a word line.

[0052] Figure 8 The Pristine SiN project shows Figure 6 The spacing distance (line width of word lines) between silicon nitride films (SiN) measured in the structure of ALE SiN is shown in Figure 1. Figure 7 The spacing distance (line width of word lines) between silicon nitride films (SiN) measured in the structure of . Similarly, the Pristine SiO2 item shows Figure 6 The ALE SiO2 project shows the spacing distance (line width of word lines) between silicon oxide films (SiO2) measured in the structure. Figure 7 The spacing distance between silicon oxide films (SiO2) (the line width of word lines) measured in the structure of FIG. 1 is 10. In this experimental example, the unit cycle consisting of the surface treatment step S20 and the etching step S30 is repeated 10 times.

[0053] Reference Figures 6 to 8 In the thin film structure in which silicon nitride film (SiN) and silicon oxide film (SiO2) are alternately stacked, the spacing distance between the silicon nitride films (SiN) arranged in the first position at the top increases from 121.1nm before the application of the unit cycle to 127.3nm after repeated application of 10 unit cycles, an increase of 6.2nm. On the contrary, the spacing distance between silicon oxide films (SiO2) increases from 115.2nm before the application of the unit cycle to 114.8nm after repeated application of 10 unit cycles, a decrease of 0.4nm.

[0054] The average of these measurement results shows that the etching amount per cycle (EPC) of silicon nitride film (SiN) is about On the contrary, the etching amount per unit cycle (EPC) of silicon oxide film (SiO2) is / Cycle, when the above-mentioned thin film etching method is applied to a substrate on which a pattern including an oxide film and a nitride film is formed, the etching selectivity ratio between the oxide film and the nitride film has a certain difference.

[0055] According to this experimental result, in the etching step S30, the unit cycle etching amount (EPC) of the silicon nitride film (SiN) and the silicon oxide film (SiO2) is different, the etching ratios of the oxide layer formed on the silicon oxide film (SiO2) and the oxide layer formed on the silicon nitride film (SiN) are different from each other, and the etching rate of the oxide layer formed on the silicon nitride film (SiN) is greater than the etching rate of the oxide layer formed on the silicon oxide film (SiO2). Based on this difference, it can be understood that the physical properties of the oxide layer formed on the silicon oxide film (SiO2) and the oxide layer formed on the silicon nitride film (SiN) in the surface treatment step S20 are different from each other.

[0056] Fig. 9 This is a graph for in-situ monitoring of the etched thickness (EtchedThickness) based on the etching time (Etching time) when a thin film etching method according to an embodiment of the present invention is applied to a structure in which a silicon nitride film (SiN) and a silicon oxide film (SiO2) are alternately deposited. Fig.10 : is a graph showing the result of calculating the amount of fluorine (F) atoms adsorbed to the surface of a thin film during execution of the thin film etching method according to one embodiment of the present invention.

[0057] Reference Fig. 9 and Fig.10 It can be confirmed that fluorine (F) atoms are adsorbed on the surface of silicon oxide film (SiO2) and have a predetermined incubation time. That is, it takes a considerable amount of time for halide-based substances to be adsorbed on the surface of silicon oxide film (SiO2) and formed into SiFx substances and etched. On the contrary, silicon nitride film (SiN) has hydrogen groups on the surface compared to silicon oxide film (SiO2), and the time required for halide-based substances to be adsorbed on the surface of silicon nitride film (SiN) and formed into SiFx substances and etched is shorter.

[0058] Refer to the aforementioned Figure 6 to Figure 7 It can be confirmed that when a thin film etching method of an embodiment of the present invention is applied, the thickness of the silicon oxide film (SiO2) increases slightly. For example, the spacing distance between the silicon oxide films (SiO2) located at the first position of the stacked pattern is slightly reduced from 115.2nm to 114.8nm, and it can be inferred that a small amount of halide is adsorbed on the surface of the silicon oxide film (SiO2). From this, it can be understood that fluorine (F) atoms are adsorbed on the surface of the silicon oxide film (SiO2) and have a predetermined incubation time. It takes a considerable amount of time for the halide-based substances to be adsorbed on the surface of the silicon oxide film (SiO2) and formed into SiFx substances and etched, and there is a difference in etching rate between silicon nitride film (SiN) and silicon oxide film (SiO2).

[0059] The speed at which silicon oxide film (SiO2) encounters fluorine (F) to form volatile SiF4 substances is slower than the speed at which silicon nitride film (SiN) encounters fluorine (F) to form volatile SiF4 substances. Since silicon nitride film (SiN) is deposited using SiH4 and NH3, there are more H inside the silicon nitride film. When the H content in the silicon nitride film (SiN) increases, the density of the silicon nitride film will decrease, the compressive stress will become higher, the reactivity of the etchant will increase, and the etching rate will become faster. In contrast, since silicon oxide film (SiO2) does not contain H, the speed at which it becomes a volatile SiF4 substance will be slower compared to SiN:H. In short, the difference in etching speed in the film is due to the density difference caused by the inclusion of H.

[0060] Fig.11 This is a graph comparing the etching thickness of silicon oxide film (SiO2) and silicon nitride film (SiN) based on the process temperature. Fig.11 The horizontal axis represents the process temperature, for example, the temperature of a heater installed in an etching device for performing the thin film etching method on a substrate on which a silicon oxide film (SiO2) and / or a silicon nitride film (SiN) is formed. The thin film etching method of an embodiment of the present invention is performed in a low temperature range where the process temperature is lower than 70°C.

[0061] Reference Fig.11 The higher the process temperature, the higher the etching rate of silicon nitride film (SiN) will be than that of silicon oxide film (SiO2), and the lower the process temperature, the higher the etching rate of silicon oxide film (SiO2) will be than that of silicon nitride film (SiN).

[0062] The following is an explanation of the phenomenon that the etching rate of silicon oxide film (SiO2) is higher than that of silicon nitride film (SiN) at low temperature (e.g., 50°C). The etchant formed by injecting reaction gases NH3 and NF3 is NH3(HF)3. At low temperatures, the silicon oxide film (SiO2) reacts with the etchant, i.e., NH3(HF)3, to form a salt, i.e., (NH4)2SiF6, as shown in the following reaction formula.

[0063] NH3(HF)3+HF+SiO2→(NH4)2SiF6+H2O

[0064] In addition, hydrofluoric acid is formed by the reaction of the H 2 O and the HF.

[0065] The thin film etching method of the embodiment of the present invention is applicable to the process of making salt (Salt) at low temperature and removing silicon oxide film (SiO2), which can be understood as an example of ALE (Atomic Layer Etching). It is applicable because it is easy to form salt (Salt) that is thermally decomposed / sublimated at low temperature, namely (NH4)2SiF6. When etching silicon oxide film (SiO2) and silicon nitride film (SiN), the etching rate (Etch Rate) of hydrofluoric acid (hydrofluoric acid) containing -OH is higher. When the temperature is low, F adsorbed on the surface of silicon oxide film (SiO2) and H generated from NH3 meet to form hydrofluoric acid (hydrofluoric acid), so the etching rate (Etch Rate) of silicon oxide film (SiO2) is significantly higher than that of silicon nitride film (SiN).

[0066] In contrast, when the temperature rises (e.g., 130°C), the salt, i.e., (NH4)2SiF6, will sublime the instant it contacts the film surface, and more hydrogen fluoride will be formed than hydrofluoric acid, so the etching rate of the silicon nitride film (SiN) is relatively high.

[0067] However, as referenced Figures 3 to 8 As described, in the thin film etching method of the embodiment of the present invention, at a relatively low process temperature (for example, a temperature below 70°C), the silicon oxide film (SiO2) cannot be etched, but the silicon nitride film (SiN) will be etched. This is because the surface treatment step S20 and the etching step S30 are performed sequentially, and the physical properties of the oxide layer formed on the silicon oxide film (SiO2) and the oxide layer formed on the silicon nitride film (SiN) in the surface treatment step S20 are different from each other, and the etching rate of the oxide layer formed on the silicon nitride film (SiN) in the etching step S30 is greater than the etching rate of the oxide layer formed on the silicon oxide film (SiO2). When the thin film etching method of the embodiment of the present invention is presented at a relatively low process temperature, the degree of fluorine (F) adsorbed to the thin film due to the etching gas can be reduced, the damage to the thin film can be reduced, and it is easy to be applied to the self-limitation process.

[0068] Fig.12 This is a graph showing RGA intensity of components of an etchant analyzed in a thin film etching method according to an embodiment of the present invention.

[0069] Reference Fig.12The NH-F series of etchants on the right are relatively heavy polymers, and react when the etching process temperature is above 110°C. In the thin film etching method of an embodiment of the present invention where the etching process temperature is less than 70°C, the main etchant is the HF2 substance shown on the left. Furthermore, when O2 is added to the etching gas, i.e., the mixed gas of NH3 and NF3 or the halide gas, H2O substances will be generated, which will remove the fluorine (F) substances adsorbed on the surface to a certain extent and reduce the etching rate.

[0070] As described above, in order to perform a thin film etching method according to an embodiment of the present invention at low temperature, a remote plasma process may be performed. The following is described in connection with a substrate processing device for performing the thin film etching method according to some embodiments of the present invention. For example, the substrate processing device may be used to perform the surface treatment step S20 and / or the etching step S30.

[0071] Fig.13 FIG. 1 is a schematic diagram showing a substrate processing apparatus 100 for explaining a thin film etching method according to some embodiments of the present invention.

[0072] Reference Fig.13 The substrate processing apparatus 100 may include a process chamber 110 , a gas injection portion 120 , a substrate support portion 130 , and a remote plasma reactor 150 .

[0073] More specifically, a reaction space 112 for processing a substrate S may be formed on the process chamber 110. The process chamber 110 may be connected to a vacuum pump (not shown in the drawings) through an exhaust pipe 114 to form a vacuum atmosphere. Furthermore, the process chamber 110 may include an inlet and outlet for loading or unloading the substrate S into the reaction space 112 and a door structure for closing (not shown in the drawings). The process chamber 110 may have a variety of shapes, for example, it may include a side wall portion defining the reaction space 112 and a cover portion located at the upper end of the side wall portion, such as a top lead.

[0074] The gas injection unit 120 may be coupled to the process chamber 110 to supply a process gas supplied from the outside of the process chamber 110 to the reaction space 112. More specifically, the gas injection unit 120 is coupled to the process chamber 110 to face the substrate support unit 130. For example, the gas injection unit 120 is disposed at an upper portion of the process chamber 110 to inject a process gas toward the substrate S mounted on the substrate support unit 130.

[0075] In some embodiments, the gas injection unit 120 may include an inlet 122 for introducing a process gas, and a distribution plate 124 that injects the dispersed process gas into the reaction space 112 through the inlet 122. Furthermore, the gas injection unit 120 may further include a blocker plate for dispersing the process gas passing through the inlet 122. For example, a connecting pipe 152 for connecting the remote plasma reactor 150 and the gas injection unit 120 is provided on the inlet 122, and the process gas is supplied to the gas injection unit 120 through one side of the connecting pipe 152.

[0076] In some embodiments, the gas injection unit 120 may have various forms such as a shower head form, a nozzle form, etc. When the gas injection unit 120 is in the shower head form, the gas injection unit 120 is coupled to the process chamber 110 in a form that partially covers the upper portion of the process chamber 110. For example, the gas injection unit 120 may be coupled to a cover or a top lead of the process chamber 110.

[0077] The substrate support part 130 is coupled to the process chamber 110 in the processing space 112 to support the substrate S. For example, the substrate support part 130 is provided to the process chamber 110 to be opposite to the gas injection part 120. Furthermore, the substrate support part 130 may have a heater 182 for heating the substrate S. For example, the heater 182 may be provided in the substrate support part 130. The heater power supply part 180 is connected to the heater 182 to apply power to the heater 182, and additionally, an AC filter 185 is interposed between the heater 182 and the heater power supply part 180.

[0078] The shape of the upper plate of the substrate support part 130 roughly corresponds to the shape of the substrate S, but is not limited thereto, and can be a variety of shapes larger than the substrate S to stably place the substrate S. In one example, the shaft of the substrate support part 130 can be connected to an external motor (not shown in the drawings) to be able to rise and fall. In this case, in order to maintain airtightness, a bellows (not shown in the drawings) can be connected. Furthermore, since the substrate S is placed on the substrate support part 130, it can be called a substrate placement part, a susceptor, etc.

[0079] In some embodiments, the substrate support part 130 is fixed to the upper part thereof in order to apply electrostatic force to the substrate S, and further includes an electrostatic electrode. In this case, the electrostatic electrode receives DC power from an electrostatic force power supply part (not shown in the drawings).

[0080] A remote plasma reactor 150 is provided outside the process chamber 110 and connected to the gas injection unit 120. The remote plasma reactor 150 may be connected to the gas injection unit 120 through a connection pipe 152. Furthermore, the process gas flows into the remote plasma reactor 150 through an inflow pipe 154. The remote plasma reactor 150 may be referred to as a remote plasma generator.

[0081] Furthermore, the remote plasma reactor 150 is connected to the plasma power supply unit 140 for applying power. For example, the plasma power supply unit 140 may include at least one RF power supply to apply at least one RF (radiofrequency) power to the process chamber 110. The remote plasma reactor 150 may form a plasma atmosphere by an inductively coupled plasma (ICP) method, a capacitively coupled plasma (CCP) method, a toroidal plasma method, a microwave (MW) method, etc.

[0082] The remote plasma reactor 150 receives at least one process gas supplied through the inflow pipe 154, is applied with plasma power to form a plasma atmosphere inside, and starts the process gas to generate an etchant. For example, the etchant may include a plurality of free radicals, which are supplied to the gas injection unit 120 through the connection pipe 152 and injected onto the substrate S through the gas injection unit 120. Optionally, the connection pipe 152 is heated to prevent the generation or adsorption of byproducts. For example, a heater jacket or a heating tape is wound around the connection pipe 152.

[0083] In some embodiments, the gas injection portion 120 receives additional process gas not through the remote plasma reactor 150 but through a side pipe 153 connected to the middle of the connecting pipe 152. The process gas supplied through the side pipe 153 and the process gas or radicals supplied through the remote plasma reactor 150 may mix or react with each other in the connecting pipe 152.

[0084] In some embodiments, the substrate processing apparatus 100 may be applied as a surface processing apparatus or an etching apparatus for performing surface processing or etching on a thin film of the substrate S.

[0085] Reference Figure 4 , Figure 5 and Fig.13, a composite film pattern 56 is formed on the substrate S. For example, the substrate S includes a semiconductor wafer 52, and a structure for forming a semiconductor element is formed on the semiconductor wafer 52. More specifically, the composite film pattern 56 can be formed on the semiconductor wafer 52. The semiconductor wafer 52 can include semiconductor materials, such as single crystal structures such as silicon, germanium, and silicon-germanium, and further, can also include a semiconductor epitaxial layer, etc.

[0086] The composite film pattern 56 may include a pattern structure in which a plurality of first insulating layers 54 and a plurality of second insulating layers 55 are alternately stacked. After the plurality of first insulating layers 54 and the plurality of second insulating layers 55 are alternately stacked, they are patterned using photolithography and etching techniques to form a plurality of trenches 57. For example, the plurality of first insulating layers 54 include silicon oxide films, and the plurality of second insulating layers 55 include silicon nitride films.

[0087] In some embodiments, the substrate processing apparatus 100 is used to process a substrate S. For example, the substrate S is processed while being placed on the substrate support 130 in the process chamber 110. More specifically, the steps of introducing the substrate S into the process chamber 110 and placing it on the substrate support 130 may be performed.

[0088] In order to perform the surface treatment step S20 of the thin film etching method of some embodiments, after the remote plasma reactor 150 is started by supplying an oxygen-containing gas containing at least one of O2, O3, H2O, H2O2 and N2O, the started oxygen-containing gas is discharged from the remote plasma reactor 150 to reach the composite film pattern 56 on the substrate S. In a modified embodiment of the present invention, the surface treatment step S20 of the thin film etching method can be performed in a hot atmosphere using a heater or the like instead of the plasma atmosphere using the remote plasma reactor 150.

[0089] In addition, in order to perform the etching step S30 of the thin film etching method of some embodiments, it may include: an etchant supplying step, using the remote plasma reactor 150 to start the first gas G1 including at least one of a halogen gas and a hydrogen-containing gas to generate an etchant ET and discharge it in the direction of the gas injection part 120; a second gas supplying step, after the etchant ET is discharged from the remote plasma reactor 150, before it reaches the composite film pattern 56 on the substrate S, the second gas G2 containing an inert gas is supplied to the etchant ET; and an etching step, at least using the etchant ET or the reactant of the etchant to relatively at least partially etch the multiple second insulating layers 55 for the multiple first insulating layers 54.

[0090] For example, the first gas G1 is supplied into the remote plasma reactor 150 through the inflow pipe 154, and the second gas G2 is supplied into the connection pipe 152 through one side of the connection pipe 152. More specifically, the second gas G2 is supplied into the connection pipe 152 through the side pipe 153 connected to one side of the connection pipe 152.

[0091] In order to generate the etchant ET or the reactant of the etchant, the first gas G1 and the second gas G2 may form various combinations. Four examples of combinations of the first gas G1 and the second gas G2 are shown below.

[0092] In the first example, the first gas G1 includes a halogen gas, and the second gas G2 includes an inert gas, a hydrogen-containing gas, and an oxygen-containing gas. In this case, the halogen gas is activated to form an etchant ET, and at least a portion of the etchant ET reacts with the hydrogen-containing gas and the oxygen-containing gas to generate a reactant of the etchant ET.

[0093] In the second example, the first gas G1 includes a halogen gas and a hydrogen-containing gas, and the second gas G2 includes an inert gas and an oxygen-containing gas. In this case, the halogen gas and the hydrogen-containing gas are activated or partially reacted to form an etchant ET, and at least a portion of the etchant ET reacts with the oxygen-containing gas to generate a reactant of the etchant ET.

[0094] In the third example, the first gas G1 includes halogen gas, hydrogen-containing gas and oxygen-containing gas, and the second gas G2 includes inert gas. In this case, the halogen gas, hydrogen-containing gas and oxygen-containing gas are activated or partially reacted to form the etchant ET.

[0095] In the fourth example, the first gas G1 includes a hydrogen-containing gas, and the second gas G2 includes an inert gas, a halogen gas, and an oxygen-containing gas. In this case, the hydrogen-containing gas is activated to form an etchant ET, and at least a portion of the etchant ET reacts with the halogen gas and the oxygen-containing gas to form a reactant of the etchant ET.

[0096] In the aforementioned example, the first gas G1 may further include an inert gas, such as Ar gas, so as to generate plasma in the remote plasma reactor 150 .

[0097] The halogen gas acts as a source gas for generating the etchant ET, and may contain, for example, a halogen-based gas such as fluorine (F) or chlorine (Cl). The inert gas in the second gas G2 acts to increase the reactivity of the etchant ET, and for this purpose, is supplied to the etchant ET on the flow path of the etchant ET between the remote plasma reactor 150 and the substrate S on the substrate support 130. The inert gas in the second gas G2 is supplied after the exhaust end of the remote plasma reactor 150, and thus can be distinguished from the inert gas in the first gas G1 supplied to the remote plasma reactor 150.

[0098] In some embodiments, in the etchant supplying step, the etchant ET is supplied to the gas injection part 120 through the connecting pipe 152 connecting the remote plasma reactor 150 and the gas injection part 120, and in the second gas supplying step, the inert gas is supplied to the etchant ET flowing in the connecting pipe 152 through the side pipe 153 connected to the middle of the connecting pipe 152.

[0099] For example, the halogen gas includes NF3 gas, the hydrogen-containing gas includes NH3 gas, the oxygen-containing gas includes at least one of O2, O3, H2O, H2O2 and N2O, and the inert gas includes Ar gas. In the remote plasma reactor 150, the NF3 gas is decomposed to generate fluorine (F) or fluorine radicals. Optionally, a mixed gas of NF3 gas and Ar gas is supplied to the remote plasma reactor 150 through the inflow pipe 154. As a result of OES (optical emission spectroscopy) analysis in the connecting pipe 152, a fluorine (F) peak is observed.

[0100] As described above, the Ar gas in the first gas G1 supplied through the inflow pipe 154 and the Ar gas in the second gas G2 supplied through the side pipe 153 can be distinguished in terms of function. The Ar gas in the first gas G1 can play a role in adjusting the ignition, pressure or concentration of the plasma in the remote plasma reactor 150. On the contrary, the Ar gas supplied as the inert gas in the second gas G2 can increase the number of adsorbed etchants ET and improve the etching reactivity. For example, when the Ar gas in the second gas G2 is supplied to the connecting pipe 152, the Ar gas is ionized based on gas collisions to generate electrons, and based on these electrons, fluorine or fluorine radicals are negatively ionized.

[0101] like Fig.14As shown, negatively ionized fluorine or fluorine free radicals can generate fluorine complexes (Fcomplex), such as 2F. Since the number of combinations of the etchant adsorbed on the film is fixed, as this fluorine complex is adsorbed on the film, the concentration of fluorine adsorbed on the film will increase compared to a single fluorine or fluorine free radical adsorbed on the film. Accordingly, the concentration of fluorine adsorbed on the film increases and volatile compounds, such as SiF4, are formed more quickly, thereby increasing the etching rate. Therefore, the second gas G2 inert gas plays the role of supplying electrons to the etchant ET.

[0102] like Fig.15 As shown in FIG. 1 , the higher the flow rate of the Ar gas in the second gas G2 supplied to the etchant ET, the higher the etching rate (Etch Rate) of the ALD SiN film, but the ALD SiO2 film can hardly be etched. Accordingly, the higher the flow rate of the Ar gas in the second gas G2, the greater the etching selectivity (Etch Selectivity) of the ALD SiN film to the ALD SiO2 film. Considering that the Ar gas in the second gas G2 is an inert gas and does not participate in the etching reaction itself, it can be explained that the Ar gas in the second gas G2 increases the concentration of the halogen adsorbed on the film to increase the etching rate. For example, in Fig.15 Under the condition of , the temperature of the heater 182 or the substrate supporting part 130 can be below 70°C.

[0103] In addition, if Fig.16 As shown in FIG. 1 , as a comparative example, as the flow rate of the Ar gas in the first gas G1 supplied to the remote plasma reactor 150 through the inflow pipe 154 increases, the etching rate of the SiN film decreases instead. Therefore, the functions of the Ar gas in the first gas G1 and the Ar gas in the second gas G2 are completely different and have opposite effects.

[0104] The present invention is described with reference to the embodiments shown in the accompanying drawings, but this is only exemplary, and a person skilled in the art of the present invention will understand that various modifications and equivalent other embodiments can be derived therefrom. Therefore, the true technical protection scope of the present invention should be determined according to the technical ideas of the attached claims.

Claims

1. A thin film etching method, characterized in that: The steps include: a preparation step of preparing a substrate on which a pattern including a nitride film is formed; a surface treatment step of treating the surface of the nitride film with an oxygen-containing gas to oxidize at least a portion of the surface; and an etching step of supplying an etching gas onto the oxide layer in order to remove at least a portion of the oxide layer on the surface of the nitride film oxidized by the surface treatment step, The surface treatment step and the etching step are repeatedly performed periodically.

2. A thin film etching method, characterized in that: The steps include: A preparation step of preparing a substrate on which a pattern including an oxide film and a nitride film is formed; a surface treatment step of treating the surfaces of the oxide film and the nitride film with an oxygen-containing gas to oxidize at least a portion of the surfaces; and an etching step of supplying an etching gas onto the oxide layer in order to remove at least a portion of the oxide layer on the surface of the nitride film oxidized by the surface treatment step, The surface treatment step and the etching step are repeatedly performed periodically.

3. The thin film etching method according to claim 2, characterized in that: In the surface treatment step, an oxide layer formed on the oxide film and an oxide layer formed on the nitride film have different physical properties from each other.

4. The thin film etching method according to claim 3, characterized in that: In the etching step, an oxide layer formed on the oxide film and an oxide layer formed on the nitride film have different etching ratios from each other.

5. The thin film etching method according to claim 4, characterized in that: An etching rate of an oxide layer formed on the nitride film is greater than an etching rate of an oxide layer formed on the oxide film.

6. The thin film etching method according to claim 1 or 2, characterized in that: The oxygen-containing gas includes at least one of O2, O3, H2O, H2O2 and N2O.

7. The thin film etching method according to claim 1 or 2, characterized in that: The etching gas is a mixed gas of NH 3 and NF 3 or a halide-based gas.

8. The thin film etching method according to claim 1 or 2, characterized in that: The surface treatment step is performed under a plasma atmosphere.

9. The thin film etching method according to claim 1 or 2, characterized in that: The surface treatment step is performed under a hot atmosphere.

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