Method of treating thin films and method of manufacturing memory device

Abstract

According to one embodiment of the present invention, a thin film processing method comprises the steps of: supplying a surface modifying agent to the interior of a chamber on which a substrate having a thin film formed is placed; purging the interior of the chamber; supplying an etching agent to the interior of the chamber; and purging the interior of the chamber, wherein the etching agent is represented by any one of the following: , , .

Description

Technology Field

[0001] The present invention relates to a thin film processing method and a method for manufacturing a memory device including the same, and more specifically, to a method for processing an ultrafine thin film using a surface modifying agent and an etching agent and a method for manufacturing a memory device including the same. Background Technology

[0003] As the miniaturization of semiconductor devices accelerates, there is a need for thinner and more uniform deposition of metal nitride films, which are actively used as electrode materials, electrodes, barriers, liners, or gate electrodes for semiconductor devices. Research is being conducted in various fields regarding this, and among them, research on depositing metal nitride films with uniform and thin thicknesses using island growth is receiving attention.

[0004] Metal nitride films generally have a problem in that the thin film surface is relatively rough due to island growth characteristics. In particular, while the bulk interior of metal nitride films exhibits uniform stability, the surface displays high surface energy, and due to the tendency to maximize internal bonds, island growth characteristics become prominent, resulting in a rough surface. Furthermore, metal nitride films have limitations in that atomic rearrangement occurs easily due to the weak directionality of the metal bonds, but the strength of the metal bonds is strong, causing the film to easily transform into a crystalline phase and increase the grain size. Consequently, according to conventional technology, metal nitride films had limitations in that they had poor surface roughness characteristics and were difficult to deposit thinly, which led to the problem of additional deterioration of interfacial characteristics during subsequent film deposition.

[0005] Meanwhile, conventional atomic layer etching methods have been performed using etchants such as hydrogen fluoride (HF) and hydrogen chloride (HCl), which facilitate surface layer modification due to their strong reactivity. However, while these etchants offer the advantage of strong reactivity, they present problems such as the inability to precisely control the etching rate based on the input amount or the difficulty of selectively etching only very thin layers. Even minute changes in process conditions cause significant fluctuations in the etching amount, and the etching reaction is self-limiting, making precise atomic-layer etching difficult. Furthermore, because conventional etchants react non-selectively due to their high reactivity, etching can occur in localized or non-uniform areas, leading to increased surface roughness in micro-pattern processes involving complex structures. Moreover, the atoms constituting conventional etchants (e.g., F, Cl) are very small, allowing them to penetrate into unwanted underlying regions, causing damage and consequently degrading the electrical characteristics of the device.

[0006] Accordingly, in order to effectively improve the surface roughness of metal nitride films with island growth characteristics and to realize ideal Atomic Layer Etch (ALE), which is the opposite concept of Atomic Layer Deposition (ALD), there is a need for the development and research of thin film processing technology using a new etchant that can maintain a constant etched thickness through the termination of the surface reaction and precisely control the etching rate. Prior art literature

[0008] Korean Patent Publication No. 2307542 (October 1, 2021) The problem to be solved

[0009] One objective of the present invention is to provide a method for processing a thin film with a uniform thickness and a method for manufacturing a memory device including the same.

[0010] One objective of the present invention is to provide a thin film treatment method capable of effectively improving the surface roughness of a metal nitride film having island growth characteristics.

[0011] One objective of the present invention is to provide a thin film treatment method that can prevent deterioration of interface characteristics during subsequent film deposition by improving the surface roughness of a metal nitride film.

[0012] One objective of the present invention is to provide a thin film processing method capable of precisely controlling the etching rate and enabling uniform etching at the atomic layer level using an etchant having self-limiting reaction characteristics.

[0013] One objective of the present invention is to provide a thin film processing method that can minimize damage to the underlying region and prevent degradation of the electrical characteristics of the device through selective and controllable etching, unlike conventional highly reactive etchants.

[0014] The problems that the present invention aims to solve are not limited to those described above, and problems not mentioned will be clearly understood by those skilled in the art from this specification and the attached drawings. means of solving the problem

[0016] According to one embodiment of the present invention, a thin film processing method comprises the steps of: supplying a surface modifying agent to the interior of a chamber on which a substrate having a thin film formed is placed; purging the interior of the chamber; supplying an etching agent to the interior of the chamber; and purging the interior of the chamber, wherein the etching agent is represented by any one of the following <Chemical Formula 1>, <Chemical Formula 2>, and <Chemical Formula 3>.

[0017] <Chemical Formula 1>

[0018]

[0019] <Chemical Formula 2>

[0020]

[0022] In the above <Chemical Formula 1> or <Chemical Formula 2>,

[0023] X1 to X2 may each be the same or different from one another and are independently selected from hydrogen, a chlorine element, and a chloroalkyl group having 1 to 5 carbon atoms, and

[0024] R1 to R3 may each be the same or different from one another and are independently selected from hydrogen, linear, branched, or cyclic alkyl groups having 1 to 5 carbon atoms, aryl groups having 6 to 12 carbon atoms, hydroxyl groups having 0 to 4 carbon atoms, and alkoxy groups having 0 to 4 carbon atoms.

[0025] <Chemical Formula 3>

[0026]

[0027] In the above <Chemical Formula 3>, n is each independently selected from integers from 0 to 5, X1 to X3 are each independently selected from an alkoxy group having 1 to 5 carbon atoms and a dialkylamine group having 1 to 5 carbon atoms, and R is selected from hydrogen, a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a dialkylamine group having 1 to 5 carbon atoms.

[0028] The above etchant may be any one of Dichloromethyl methyl ether (DCMME), 1-chloromethyl ethyl ether (1-CMEE), Dimethylformamide dimethyl acetal (DFDA), and Tris(dimethylamino)methane (TDMAM).

[0029] The above method may further include a method of forming the thin film on the substrate by atomic layer deposition (ALD) prior to the step of supplying the surface modifying agent.

[0030] The above thin film may be a metal nitride thin film having a group 4 metal as the central element.

[0031] The above group 4 metal may be any one of Titanium (Ti), Zirconium (Zr), and Hafnium (Hf).

[0032] The above thin film may be a metal nitride thin film having a group 5 metal as a central element.

[0033] The above Group 5 metal may be any one of Vanadium (V), Niobium (Nb), and Tantalum (Ta).

[0034] The above thin film may be a metal film or a metal nitride thin film having a group 6 metal as a central element.

[0035] The above group 6 metal may be either Molybdenum (Mo) or Tungsten (W).

[0036] The above surface modifier may be any one of O3, O2, H2O, and H2O2.

[0037] According to one embodiment of the present invention, a method for manufacturing a memory device may include the thin film processing method described above.

[0038] The means for solving the problem of the present invention are not limited to the means for solving the problem described above, and unmentioned means for solving the problem will be clearly understood by those skilled in the art from this specification and the attached drawings. Effects of the invention

[0040] According to a thin film treatment method according to one embodiment of the present invention, a thin film of a uniform thickness can be formed by using a surface modifying agent and an etching agent.

[0041] According to a thin film processing method of one embodiment of the present invention, the etching rate can be precisely controlled by using an etchant having self-limiting reaction characteristics. This resolves the difficulty of controlling the etching rate associated with conventional highly reactive etchants and enables precise thickness control at the atomic layer level.

[0042] According to a thin film treatment method according to one embodiment of the present invention, it can be effectively applied not only to metal nitride films but also to oxide films and metal films having various transition metals of groups 4 to 6 as central elements, thereby providing versatility that can be utilized in a wide range of semiconductor device manufacturing processes.

[0043] The effects of the present invention are not limited to the effects described above, and unmentioned effects will be clearly understood by those skilled in the art from this specification and the accompanying drawings. Brief explanation of the drawing

[0045] FIG. 1 is a diagram showing a thin film processing method according to an embodiment of the present invention. FIG. 2 is a graph schematically showing the supply cycle according to an embodiment of the present invention. Figure 3 is a graph schematically showing the supply cycle according to the comparative example. Figures 4 to 6 are drawings showing the thickness and roughness of TiN thin films according to the pre-etching, comparative example, and experimental example 1. Figure 7 is a graph analyzing the thickness of the thin film according to whether the etchant is supplied at each process temperature according to Experimental Example 2. Figure 8(a) is a graph showing the EPC according to the number of cycles in Experimental Example 3. Figure 8(b) is a graph showing the EPC according to the amount of etchant supplied in Experimental Example 3. Figure 9 is a diagram showing the thickness and roughness of the TiN thin film before and after etching according to Experimental Example 4. Figure 10 is a diagram showing the thickness and roughness of a TiN thin film before and after etching according to Experimental Example 5. Figure 11(a) is a graph showing the EPC according to the number of cycles in Experimental Example 6. Figure 11(b) is a graph showing the EPC according to the amount of etchant supplied in Experimental Example 6. Figure 12 is a graph showing the thickness of the thin film according to the number of cycles for each metal nitride film according to Experimental Example 7. Figure 13 is a graph showing the change in thickness of the thin film according to etching. Specific details for implementing the invention

[0046] The aforementioned objects, features, and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings. However, as the present invention is subject to various modifications and may have various embodiments, specific embodiments are illustrated in the drawings and described in detail below.

[0047] Throughout the specification, identical reference numbers generally represent identical components. Additionally, components with identical functions within the same scope of concept appearing in the drawings of each embodiment are described using the same reference numeral, and redundant descriptions thereof are omitted.

[0048] If it is determined that a detailed description of known functions or configurations related to the present invention could unnecessarily obscure the essence of the invention, such detailed description is omitted. Furthermore, numbers used in the description of this specification (e.g., First, Second, etc.) are merely identification symbols to distinguish one component from another.

[0049] In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0050] In the following embodiments, terms such as "include" or "have" mean that the features or components described in the specification are present, and do not preclude the possibility that one or more other features or components may be added.

[0051] In the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are arbitrarily depicted for convenience of explanation, and the present invention is not necessarily limited to what is illustrated.

[0052] Where an embodiment can be implemented differently, the order of a particular process may be performed differently from the order described. For example, two processes described consecutively may be performed substantially simultaneously or proceed in the reverse order of the description.

[0054] The present invention relates to a method for depositing a thin film, particularly a metal nitride film, with a uniform and thin thickness through island growth. Island growth refers to the growth of a thin film in an island shape when depositing it on a substrate. Thin films grown in an island shape generally have a rough surface and are difficult to deposit as fine films.

[0055] The present invention relates to a method for making a thin and uniform thin film from an Irish-grown thin film through an atomic layer etching (ALE) process, and the surface roughness of the thin film can be improved through the atomic layer etching process.

[0056] The principle by which surface roughness is improved according to the present invention is as follows. Protruding portions of the surface have higher surface energy and a wider exposure range than flat portions. Additionally, because they are less affected by surrounding atoms, modification proceeds more in the protruding portions compared to unmodified portions when a surface modifier is applied. Conversely, indented portions of the surface have lower surface energy due to inverse curvature and undergo less modification because they are more affected by surrounding atoms. The more modification progresses in a portion, the more etching occurs when an etchant is applied, and the protruding portions gradually decrease. Therefore, surface roughness can be improved by performing an atomic layer etching (ALE) process on a thin film.

[0058] Hereinafter, with reference to FIGS. 1 to 13, a thin film treatment method according to the present invention will be described in more detail.

[0059] FIG. 1 is a diagram showing a thin film processing method according to an embodiment of the present invention, and FIG. 2 is a graph schematically showing a supply cycle according to an embodiment of the present invention. A substrate is loaded into the interior of a process chamber, and the substrate has a thin film formed on its surface. The thin film is formed by atomic layer deposition (ALD) and may be formed after being loaded into the interior of the process chamber or may be loaded into the interior of the process chamber after the thin film is formed.

[0060] According to one example, the substrate may be a silicon (Si) substrate, and the thin film may be a metal nitride film, a metal oxide film, and / or a metal film deposited on the substrate by ALD.

[0061] The thin film can be deposited through island growth during the formation process.

[0062] According to one embodiment, the thin film may be a metal nitride thin film, a metal oxide thin film, and / or a metal film having a group 4 metal as the central element, and may have one of Ti, Zr, or Hf as the central element.

[0063] According to one embodiment, the thin film may be a metal nitride thin film, a metal oxide thin film, and / or a metal film having a group 5 metal as the central element, and may have one of V, Nb, or Ta as the central element.

[0064] According to one embodiment, the thin film may be a metal nitride thin film, a metal oxide thin film, and / or a metal film having a group 6 metal as the central element, and may have one of Mo or W as the central element.

[0065] Meanwhile, the following process conditions may be adjusted. Process conditions may include the temperature of the substrate or process chamber, chamber pressure, and gas flow rate.

[0066] Referring again to FIGS. 1 and 2, the substrate may be exposed to a surface modifier supplied inside the chamber, and the surface modifier may be any one of O3, O2, H2O, and H2O2. The surface modifier can react with a thin film, particularly a metal nitride film, to modify the surface of the metal nitride film. At this time, the protruding portion due to island growth has high surface energy compared to the surrounding portion, as described above, and is highly reactive. Due to its high curvature, it is relatively unaffected by surrounding atoms, which increases the possibility of collision with the surface modifier and allows it to react relatively more with the surface modifier.

[0067] After supplying the surface modifier, a purge gas (an inert gas such as nitrogen (N2), argon (Ar), and / or helium (He)) is supplied into the chamber so that unreacted materials or byproducts can be removed or purified.

[0068] After supplying the surface modifier (preferably, after supplying the surface modifier and purge gas), an etchant can be supplied into the chamber, and the thin film (metal nitride film) modified by the surface modifier can be exposed to the etchant. Since the protruding portions of the thin film modified by the surface modifier have a lower film density compared to the non-protruding portions, they react relatively well with the etchant, allowing for relatively more etching to be performed. Through this, the surface roughness caused by the protruding portions of the metal nitride film can be improved.

[0069] An etchant according to one embodiment may be represented by <Chemical Formula 1> or <Chemical Formula 2>.

[0070] <Chemical Formula 1>

[0071]

[0072] <Chemical Formula 2>

[0073]

[0074] In the above <Chemical Formula 1> or <Chemical Formula 2>,

[0075] X1 to X2 may each be the same or different from one another and are independently selected from hydrogen, a chlorine element, and a chloroalkyl group having 1 to 5 carbon atoms, and

[0076] R1 to R3 may each be the same or different from one another and may be independently selected from hydrogen, linear, branched, or cyclic alkyl groups having 1 to 5 carbon atoms, aryl groups having 6 to 12 carbon atoms, hydroxyl groups having 0 to 4 carbon atoms, and alkoxy groups having 0 to 4 carbon atoms.

[0077] According to one embodiment, the etching initiator (or etchant) may be either Dichloromethyl methyl ether (DCMME) or 1-Chloromethyl ethyl ether (1-CMEE).

[0079] Alternatively, the etchant can be represented by <Chemical Formula 3>.

[0080] <Chemical Formula 3>

[0081]

[0082] In the above <Chemical Formula 3>, n is each independently selected from integers from 0 to 5, X1 to X3 are each independently selected from an alkoxy group having 1 to 5 carbon atoms and a dialkylamine group having 1 to 5 carbon atoms, and R can be selected from hydrogen, a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a dialkylamine group having 1 to 5 carbon atoms.

[0083] Specifically, the etchant may be either Dimethylformamide dimethyl acetal (DFDA) or Tris(dimethylamino)methane (TDMAM).

[0084] Referring again to FIG. 2, after the etching agent is supplied, a purge gas (e.g., an inert gas such as Ar) is supplied into the chamber so that unreacted material or byproducts can be removed or purified.

[0085] According to one embodiment of the present invention, the source for the ALE process can be supplied via a Liquid Flow Meter (LFM) method. The LFM method involves quantitatively measuring the source in a liquid state, supplying it to a vaporizer, vaporizing it, and introducing it into a reaction chamber. Specifically, the liquid source is precisely controlled to a preset flow rate via a flow meter (LFM), and the source can be instantaneously vaporized in a heated vaporizer, mixed with a carrier gas, and then supplied into the process chamber.

[0086] According to one embodiment of the present invention, the source for the ALE process can be supplied via a vapor method. The vapor method is a method in which the source is heated within a storage vessel (canister) to form a vapor state, and then the vapor is supplied directly to the reaction chamber. Specifically, the source naturally vaporizes within a storage vessel maintained at a predetermined temperature, and the generated source vapor is moved to the reaction chamber by a carrier gas or a pressure difference. At this time, the amount of source supplied can be determined primarily by the vapor pressure of the source, the temperature of the storage vessel, and the flow rate of the carrier gas. A metering valve may be included to precisely control the supply flow rate of the source vapor. In this case, the flow rate of the source vapor can be controlled by adjusting the opening degree of the metering valve placed on the supply line.

[0088] The structure and effects of the present invention will be explained in more detail below with reference to specific embodiments, but these embodiments are intended merely to provide a clearer understanding of the present invention and are not intended to limit the scope of the present invention.

[0090] (1) Example 1

[0091] - Comparative example

[0092] A substrate on which an Irish-grown thin film (TiN) was formed was prepared, and the thickness and roughness of the thin film were measured. Then, etching was performed using an etchant without using a surface modifier. The etchant used was 1-chloromethyl ethyl ether (1-CMEE) (indicated by <Chemical Formula 4> below), and the etching was performed at a process temperature of 300℃.

[0093] <Chemical Formula 4>

[0094]

[0096] Figure 3 is a graph schematically showing the supply cycle according to the comparative example.

[0097] Referring to Fig. 3, the etching process was repeated 50 times with the following process as one cycle.

[0098] 1) Supply an etchant (1-CMEE) into the reaction chamber

[0099] 2) Supply purge gas (Ar gas) into the reaction chamber to remove unreacted materials or byproducts.

[0100] This comparative example was conducted under conditions where only an etchant was used, in order to explain the state where the ALE process is not established when only an etchant is used.

[0102] - Experimental Example 1

[0103] A substrate on which an Irish-grown thin film (TiN) was formed was prepared, and etching was performed by sequentially supplying a surface modifier and an etchant. O3 was used as the surface modifier, 1-chloromethyl ethyl ether (1-CMEE) was used as the etchant, and etching was performed at a process temperature of 300℃.

[0104] With reference to Fig. 2, the etching process was repeated 50 times with the following process as one cycle (refer to Fig. 2).

[0105] 1) Supply a surface modifier (O3) into the reaction chamber

[0106] 2) Supply purge gas (Ar gas) into the reaction chamber to remove unreacted materials or byproducts.

[0107] 3) Supply an etchant (1-CMEE) into the reaction chamber

[0108] 4) Supply purge gas (Ar gas) into the reaction chamber to remove unreacted materials or byproducts.

[0110] Figures 4 to 6 are drawings showing the thickness and roughness of TiN thin films according to the pre-etching, comparative example, and experimental example 1, respectively. The thickness was measured using a transmission electron microscope (TEM), and the roughness was measured using an atomic force microscope (AFM).

[0112] Looking at Figures 4 and 5, in the case where no surface modifier was used, the thickness due to etching decreased by about 0.6 Å from the pre-etching thickness of 98.9 Å to 98.3 Å, indicating a small amount of reduction. Furthermore, the Rq value for roughness did not improve from the pre-etching Rq value of 0.4 nm to 0.39 nm, confirming that the ALE process was not established. The changes in thin film thickness and Rq value according to Figures 4 and 5 fall within the range of measurement error, so it can be considered that there is almost no reduction. On the other hand, looking at Figures 4 and 6, the thickness of the thin film decreased by approximately 30 Å from 98.9 Å (the thickness before etching) to 70.9 Å, and the Rq value (Root Mean Square roughness, where a lower value indicates a more uniform surface) decreased from 0.4 nm (the Rq value before etching) to 0.37 nm, confirming that the roughness has improved significantly. Furthermore, referring to the TEM data, it was confirmed that the roughness has improved enough to be visible to the naked eye. Poor surface roughness leads to differences in electrical characteristics between the thin and thick parts of the thin film. In particular, as semiconductor devices become miniaturized, if the absolute thickness of the thin film decreases, the relative thickness variation becomes larger, which can adversely affect the performance uniformity and reliability of the device. Therefore, by improving surface roughness, uniformity of the thin film thickness is ensured, and through this, the quality of the interface formed in subsequent processes can be improved, thereby enhancing the electrical characteristics and yield of the device. These results indicated that a surface modifier is required for the etching process of TiN thin films, and confirmed that the ALE process is established upon the application of the surface modifier.

[0114] (2) Example 2

[0115] - Experimental Example 2 (Evaluation of etching characteristics according to temperature)

[0116] In Experimental Example 2, 1-chloromethyl ethyl ether (1-CMEE) was used as an etchant, and a TiN thin film was etched in a process temperature range of 300°C to 380°C to confirm the etching characteristics according to temperature.

[0117] Cyclic feeding of the source into the chamber was performed according to the supply cycle of Fig. 2, and O3 was used as the surface modifier. After performing 50 cycles of the etching process at each temperature condition of 300°C, 340°C, and 380°C, the change in thin film thickness was measured. Specifically, the process of supplying the surface modifier (3 seconds) -> supplying the purge gas (15 seconds) -> supplying the etchant (60 seconds) -> supplying the purge gas (30 seconds) was repeated 50 times as one cycle. At this time, Ar gas was used as the purge gas.

[0118] In addition, to compare with the case where no surface modifier was used, only the etchant (1-CMEE) was Cyclin Feeded without supplying the surface modifier according to the supply cycle of Fig. 3. Similarly, the change in thin film thickness was measured after performing 50 cycles of the etching process under each temperature condition of 300°C, 340°C, and 380°C. Specifically, in the case where no surface modifier was used, the process of supplying the etchant (60 seconds) -> supplying the purge gas (30 seconds) was repeated 50 times as one cycle. At this time, Ar gas was used as the purge gas.

[0119] Figure 7 is a graph analyzing the thickness of the thin film according to whether the etchant is supplied at each process temperature according to Experimental Example 2.

[0120] Referring to Figure 7, when only the etchant was repeatedly applied without using a surface modifier, almost no etching occurred across all temperature ranges, and the change in thin film thickness was close to zero. On the other hand, when a surface modifier was used, a decrease in thin film thickness of approximately 10 Å at 300°C, 20 Å at 340°C, and 45 Å at 380°C was observed. This indicates that the thin film thickness decreases linearly as the process temperature increases.

[0121] These results confirmed that atomic-layer thin films can be uniformly etched through surface reactions between surface modifiers and etchants, and demonstrated that the etching rate can be controlled by adjusting the process temperature. Furthermore, it was reaffirmed that the use of surface modifiers is essential for the establishment of the ALE process.

[0123] The principle by which etching performance is improved when a surface modifier is used is expected to be as follows. The surface modifier, in the form of an oxidizing agent (e.g., O₃) used in the modification step, reacts with the surface of the film to be etched to change the chemical bonding state and composition of the surface. The surface of a nitride film mainly has a bonding structure containing nitrogen species or -NH terminals; however, oxygen species bonded by the oxidizing agent are more reactive than nitrogen species, facilitating the initiation of reactions in the subsequent etching step. For example, in the case of a TiN thin film, surface oxidation can proceed according to a reaction equation such as TiN(s) + 3O₃(g) → TiO₂(s) + NO(g) + 3O₂(g), through which the surface after the modification step can be transformed into a state more suitable for the etching reaction.

[0124] In addition, during the modification process using a surface modifier in the form of an oxidizing agent, the center metal within the underlying metal film or metal nitride film increases its oxidation state by combining with oxygen; this increase in oxidation state can lower the electron density of the center metal and promote reaction with a subsequent etchant. Importantly, this modification step alters only the extreme surface region of the film to be etched, and by ensuring that only the modified surface layer participates in the etching reaction in the subsequent process, the self-limiting characteristics of the ALE process can be maintained.

[0126] - Experimental Example 3 (EPC Evaluation)

[0127] In Experimental Example 3, 1-chloromethyl ethyl ether (1-CMEE) was used as the etchant and O3 as the surface modifier, and a TiN thin film was etched at a process temperature of 300°C. As in Experimental Example 1, the change in Etch Per Cycle (EPC) according to the number of cycles and / or the amount of etchant supplied was evaluated while repeating the etching process according to the supply cycle of Fig. 2. Specifically, the process of surface modifier supply (3 seconds) -> purge gas supply (15 seconds) -> etchant supply (60 seconds) -> purge gas supply (30 seconds) was defined as one cycle. 300℃ This was repeated several times under the process temperature. At this time, Ar gas was used as the purge gas.

[0128] First, to verify the stability of the etching rate according to the number of cycles, the etching process was performed up to 60 cycles, and the source was supplied into the chamber at 0.1 g / min via the LFM method.

[0129] Figure 8(a) is a graph showing the EPC according to the number of cycles in Experimental Example 3.

[0130] In the initial cycle, relatively high EPC values ​​were observed, but as the cycle increased to 30 cycles, the EPC also decreased and remained at a practically constant level up to 60 cycles. This means that the EPC remains stable even as the cycle is increased after 30 cycles, confirming that the etching process is carried out using an atomic layer etching method, allowing for precise control of the etching rate.

[0132] In addition, to evaluate the saturation characteristics according to the etchant supply amount, EPC was measured while varying the metering valve opening value. The source was supplied via the vapor method.

[0133] Figure 8(b) is a graph showing the EPC according to the amount of etchant supplied according to Experimental Example 3.

[0134] No etching occurred when the metering valve opening was 0, and the EPC increased linearly as the supply amount increased. Subsequently, it was confirmed that at a supply amount above a certain level (metering valve opening: approximately 1.0), the EPC converged to an almost constant value and reached the saturation region. This indicates that when the etchant supply amount increases sufficiently, the surface reaction becomes saturated and the etching rate no longer increases.

[0135] Through these results, it was confirmed that the etching process of the present invention is performed as an atomic layer etching method having self-limiting characteristics, and that process reproducibility and uniformity can be secured in the saturation region. This means that, unlike conventional highly reactive etchants (etchants such as HCl and HF), the etching rate of the thin film can be precisely controlled according to the present invention.

[0137] (3) Example 3

[0138] - Experimental Example 4 (Thickness and Rq Evaluation)

[0139] In Experimental Example 4, an atomic layer etching process was performed on a TiN nitride film using O3 as a surface modifier and 1-chloromethyl ethyl ether (1-CMEE) as an etchant. The supply cycle (1 cycle) of Fig. 2 was repeated 60 times. Specifically, the process of supplying surface modifier (3 seconds) -> supplying purge gas (15 seconds) -> supplying etchant (60 seconds) -> supplying purge gas (30 seconds) was repeated 60 times at a process temperature of 300°C as one cycle. At this time, Ar gas was used as the purge gas, and transmission electron microscopy (TEM) analysis and atomic force microscopy (AFM) analysis were performed before and after the ALE process to confirm the cross-sectional structure and surface roughness changes of the thin film.

[0141] FIG. 9 is a diagram showing the thickness and roughness of a TiN thin film before and after etching according to Experimental Example 4. Specifically, FIG. 9(a) is a diagram showing the thickness and surface roughness of a TiN thin film before etching according to Experimental Example 4, and FIG. 9(b) is a diagram showing the thickness and surface roughness of a TiN thin film after etching according to Experimental Example 4.

[0142] TEM / AFM analysis results showed that the thickness of the thin film before the ALE process was measured to be 187.4 Å (=18.74 nm), and the Rq (Root Mean Square roughness) value was 0.80 nm. After the ALE process, the thickness of the thin film decreased to 157.9 Å (=15.79 nm), confirming a thickness reduction of approximately 29.5 Å. Additionally, the Rq value decreased to 0.59 nm, confirming a 26% improvement in surface roughness.

[0143] In addition, visual comparison of TEM images revealed that while irregularities were clearly observed on the upper surface of the thin film before the ALE process, the surface became relatively flat and uniform after the ALE process. This visually demonstrates that the atomic layer etching process can effectively improve surface roughness by selectively removing protruding parts of the surface.

[0144] Through these results, it was confirmed that the atomic layer etching (ALE) process using the surface modifier and etchant of the present invention can precisely reduce the thickness of the metal nitride film while simultaneously improving surface roughness. This may contribute to the improvement of interfacial characteristics during subsequent film deposition.

[0146] (4) Example 4 (Etching agent: Dimethylformamide Dimethyl Acetal (DFDA) used)

[0147] In Example 4, the etchant (1-chloromethyl ethyl ether (1-CMEE)) of Examples 2 and 3 was replaced with a dimethylformamide dimethyl acetal (DFDA) etchant to perform etching.

[0148] - Experimental Example 5 (Evaluation of thickness and roughness)

[0149] Specifically, in Experimental Example 5, an atomic layer etching (ALE) process was performed on a TiN nitride film using O3 as a surface modifier and Dimethylformamide Dimethyl Acetal (DFDA) as an etchant. The process temperature was set to 340°C, and the etching process was performed by repeating the supply cycle (1 cycle) of Fig. 2 60 times. Specifically, the process of supplying surface modifier (3 seconds) -> supplying purge gas (15 seconds) -> supplying etchant (60 seconds) -> supplying purge gas (30 seconds) was repeated 60 times at a process temperature of 340°C as one cycle. At this time, Ar gas was used as the purge gas.

[0150] Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) analyses were performed before and after the ALE process to confirm changes in the cross-sectional structure and surface roughness of the thin film.

[0151] FIG. 10 is a diagram showing the thickness and roughness of a TiN thin film before and after etching according to Experimental Example 5. Specifically, FIG. 10(a) is a diagram showing the thickness and surface roughness of a TiN thin film before etching according to Experimental Example 5, and FIG. 10(b) is a diagram showing the thickness and surface roughness of a TiN thin film after etching according to Experimental Example 5.

[0152] TEM and AFM analysis results showed that the thickness of the thin film before the ALE process was measured to be 187.4 Å (=18.74 nm), and the Rq (Root Mean Square roughness) value was 0.80 nm. After the ALE process, the thickness of the thin film decreased to 161.7 Å (=16.17 nm), confirming a thickness reduction of approximately 25.7 Å. Additionally, the Rq value decreased to 0.60 nm, confirming a 25% improvement in surface roughness.

[0153] In addition, visual comparison of TEM images revealed that while irregularities were clearly observed on the upper surface of the thin film before the ALE process, the surface became relatively flat and uniform after the ALE process. This visually demonstrates that even when using 'DFDA etchant,' the atomic layer etching process can effectively improve surface roughness by selectively removing protruding parts of the surface.

[0154] Through these results, it was confirmed that the thickness of a metal nitride film can be precisely reduced and the surface roughness effectively improved simultaneously by combining it with a surface modifier, not only when using the 1-CMEE etchant of the present invention but also when using the DFDA etchant. Furthermore, this demonstrates that various etchants having a structure similar to 1-CMEE or DFDA can be applied to thin film processing according to the present invention.

[0156] - Experimental Example 6 (EPC Evaluation)

[0157] In Experimental Example 6, 'Dimethylformamide Dimethyl Acetal (DFDA)' was used as the etchant and O3 was used as the surface modifier to etch a TiN thin film at a process temperature of 340°C. The change in Etch Per Cycle (EPC) according to the number of cycles and / or the amount of etchant supplied was evaluated while repeating the etching process according to the supply cycle of Figure 2. Specifically, the process of supplying surface modifier (3 seconds) -> supplying purge gas (15 seconds) -> supplying etchant (60 seconds) -> supplying purge gas (30 seconds) was repeated several times at a process temperature of 340°C as one cycle. At this time, Ar gas was used as the purge gas.

[0158] First, to verify the stability of the etching rate according to the number of cycles, the etching process was performed up to 60 cycles, and the source was supplied into the chamber at 0.1 g / min via the LFM method.

[0159] Figure 11(a) is a graph showing the EPC according to the number of cycles in Experimental Example 6.

[0160] In the initial cycle, a relatively high EPC value was observed, but the EPC decreased until it reached 30 cycles, and thereafter remained stable at a practically constant level up to 60 cycles. This means that the EPC remains stable even as the number of cycles increases after 30 cycles, and it was confirmed that even when using DFDA etchant, the etching process proceeds through an atomic layer etching method, allowing for precise control of the etching rate.

[0162] In addition, to evaluate the saturation characteristics according to the supply amount of etchant, EPC was measured while varying the Liquid Flow Meter (LFM) flow value.

[0163] Figure 11(b) is a graph showing the EPC according to the amount of etchant supplied according to Experimental Example 6.

[0164] When there was no etchant supply (LFM Flow = 0 g / min), no etching occurred, and it was confirmed that the EPC increased linearly as the supply amount increased. Subsequently, at a supply amount above a certain level (LFM Flow: supply amount of approximately 0.02 g / min or more), it was confirmed that the EPC converged to a practically constant value and reached the saturation region. This indicates that when the etchant supply amount increases sufficiently, the surface reaction becomes saturated and the etching rate no longer increases.

[0165] Through these results, it was confirmed that the atomic layer etching method having self-limiting characteristics is performed not only when using the 1-CMEE etchant of the present invention but also when using the DFDA etchant, and that process reproducibility and uniformity can be secured in the saturation region. In addition, various etchants having a structure similar to 1-CMEE or DFDA (i.e., etchants according to Chemical Formulas 1 to 3 (e.g., Dichloromethyl methyl ether (DCMME), Tris(dimethylamino)methane (TDMAM)) can be applied to thin film processing according to the present invention. Unlike conventional highly reactive etchants (HCl, HF), it was proven that the etching rate of the thin film can be precisely controlled by using these etchants.

[0167] (5) Example 5 (Evaluation of etching by metal nitride film)

[0168] - Experimental Example 7 (Evaluation of Thickness Change)

[0169] In Experimental Example 7, Dichloromethyl methyl ether (DCMME) was used as an etching agent and O3 was used as a surface modifier to etch TiN, TiSiN, and MoN thin films at a process temperature of 340°C.

[0170] Cyclic feeding of the source into the chamber was performed according to each supply cycle of Figures 2 and 3, and the change in thin film thickness per cycle was compared and analyzed with and without the use of a surface modifier. For each thin film, the etching process was performed up to 100 cycles. Specifically, in Experimental Example 7, the process of supplying a surface modifier (3 seconds) -> supplying a purge gas (15 seconds) -> supplying an etchant (10 seconds) -> supplying a purge gas (10 seconds) was repeated several times at a process temperature of 340°C as one cycle. At this time, Ar gas was used as the purge gas.

[0171] Figure 12 is a graph showing the thickness of the thin film according to the number of cycles for each metal nitride film according to Experimental Example 7.

[0172] It was confirmed that when only the etchant was repeatedly applied without using a surface modifier, the film thickness hardly decreased in all TiN, TiSiN, and MoN thin films as the number of cycles increased, indicating that no etching occurred. In other words, it was reconfirmed that the ALE process cannot be established when a surface modifier is not used.

[0173] On the other hand, when a surface modifier was used, the film thickness of all thin films (TiN, TiSiN, MoN) decreased linearly with increasing cycle count. Specifically, for the TiN thin film, it started with an initial thickness of approximately 75 Å and was almost completely etched after 30 cycles, with an etching rate of 2.27 Å / cycle. In the case of the MoN thin film, it also started with an initial thickness of approximately 60 Å and was almost completely etched after 30 cycles, with an etching rate of 1.84 Å / cycle. For the TiSiN thin film, it started with an initial thickness of approximately 130 Å and gradually decreased at a relatively slow rate, with an etching rate of 0.28 Å / cycle, showing a relatively lower etching rate compared to other thin films.

[0174] Through these results, it was reconfirmed that sequential surface reactions between a surface modifier and an etchant are essential for effective atomic layer etching. In addition, it was confirmed that the thin film treatment method according to the present invention can be applied not only to 1-CMEE and DFDA etchants but also to cases where DCMME etchant is used.

[0175] Furthermore, it was confirmed that the thin film processing method according to the present invention enables precise atomic-layer etching for various metal nitride films, such as TiN, TiSiN, and MoN. Additionally, it was found that the etching rate varies depending on the type of thin film, indicating its applicability to selective etching processes. In particular, it was confirmed that rapid thin film removal is possible for TiN and MoN at high etching rates, while more precise thickness control is possible for TiSiN at relatively lower etching rates. This demonstrates that the thin film processing method of the present invention possesses versatility applicable to various metal nitride films.

[0177] Through Experimental Examples 1 to 7 above, it was confirmed that a metal nitride film of thin and uniform thickness can be formed using an atomic layer etching (ALE) process with the surface modifier and etchant of the present invention. In particular, it was confirmed that the use of a surface modifier is essential for effective etching, and that the etchants represented by Chemical Formulas 1, 2, and 3 of the present invention possess self-limiting characteristics and enable precise etching at the atomic layer level. Furthermore, it was confirmed that it is applicable to various metal nitride films, such as TiSiN and MoN, as well as TiN.

[0179] The thin film treatment method of the present invention can provide the following expected effects.

[0180] First, surface roughness can be effectively improved. As confirmed in Experimental Examples 4 and 5, the surface roughness (Rq) was reduced by 25-26% compared to before etching through the atomic layer etching process, which means that protruding parts on the thin film surface were selectively removed and the surface was flattened. The improvement of surface roughness can provide the effect of improving the electrical characteristics and reliability of the device by enhancing interface characteristics during subsequent film deposition.

[0181] Second, the etching rate can be precisely controlled. As confirmed in Experimental Examples 2, 3, and 6, the etching rate can be controlled by adjusting the process temperature and / or the amount of etchant supplied. It exhibited self-limiting characteristics, where the EPC stabilizes after a certain number of cycles and reaches a saturation region when the amount of etchant supplied increases. This means that the difficulty of controlling the etching rate associated with conventional highly reactive etchants such as hydrogen fluoride (HF) and hydrochloric acid (HCl) can be resolved, and precise thickness control at the atomic layer level is possible.

[0182] Third, the reproducibility and uniformity of the process can be ensured. As confirmed in Experimental Examples 3 and 6, since the etching reaction is maintained consistently in the saturation region, the amount of etching does not fluctuate significantly even with minute changes in process conditions, thereby ensuring high reproducibility. In addition, due to the self-limiting reaction characteristics, uniform etching is possible even in the process of fine patterns with complex structures, which can prevent localized etching concentration or non-uniformity.

[0183] Fourth, damage to the underlying region can be minimized. Unlike conventional etchants such as HCl and HF, the etchant of the present invention does not have the problem of penetrating to the underlying region and causing damage, and can precisely etch only the desired region through a selective and controllable surface reaction. This can prevent the degradation of the electrical characteristics of the device and improve device reliability.

[0184] Fifth, it has versatility applicable to various metal nitride films. As confirmed in Experimental Example 7, effective etching is possible for various metal nitride films such as TiN, TiSiN, and MoN, and the etching rate varies depending on the type of thin film, making it applicable to selective etching processes. This means that it can be widely utilized in various semiconductor device manufacturing processes.

[0185] In conclusion, it was confirmed that the thin film processing method of the present invention is an excellent technology capable of overcoming the limitations of conventional technology and simultaneously achieving precise thin film thickness control, surface roughness improvement, and process reproducibility required for the manufacturing process of miniaturized semiconductor devices.

[0187] (6) Example 6 (Evaluation of applicability to various transition metal films)

[0188] - Experimental Example 8

[0189] In order to confirm whether the thin film treatment method of the present invention is applicable to various transition metal thin films, etching experiments were performed on oxide films and / or metal films having group 4 metal elements (Ti, Hf), group 5 metal elements (Nb, Ta), and group 6 metal elements (Mo, W) as central elements.

[0190] Specifically, TiO, NbO, TaO, and HfO oxide films and Mo and W metal films were prepared by depositing them on a substrate, respectively. For each thin film, O3 was used as a surface modifier and Dichloromethyl methyl ether was used as an etchant. The process temperature was set to 300°C, and according to the supply cycle shown in Figure 2, a process consisting of surface modifier supply - purging - etchant supply - purging was formed as one cycle and repeated until each thin film was sufficiently etched. Meanwhile, in the case of oxide films, the supply of the surface modifier may be omitted, and etching was performed on the oxide film formed using the oxidizing agent using an etchant.

[0192] Table 1 below shows the thickness of the thin film before and after etching, and Figure 13 is a graph showing the change in thin film thickness according to etching.

[0193] TiO NbO Tao Mo HfO W Before the etching process 107.56 52.95 51.02 140.12 53.84 102.23 After the etching process 4.76 0 12.42 1.68 19.8 0

[0195] As shown in Table 1 and Figure 13, it was confirmed that etching proceeded effectively in all transition metal thin films.

[0196] Specifically, in the case of the group 4 metal oxide film, TiO was almost completely etched, decreasing by about 95.6% from an initial thickness of 107.56 Å to 4.76 Å, and HfO was decreased by about 63.2% from an initial thickness of 53.84 Å to 19.8 Å.

[0197] In the case of the group 5 metal oxide film, NbO was completely etched from an initial thickness of 52.95 Å to 0 Å, and TaO was reduced by about 75.7% from an initial thickness of 51.02 Å to 12.42 Å.

[0198] In the case of group 6 metals, the Mo metal film was almost completely etched, decreasing by about 98.8% from an initial thickness of 140.12 Å to 1.68 Å, and the W metal film was completely etched from an initial thickness of 102.23 Å ​​to 0 Å.

[0199] Visually confirmed through Figure 13, it was observed that in all thin films, the thickness of the film, which was substantial before the process, was significantly reduced or almost completely removed after the process. In particular, it was shown that almost complete etching was possible in the case of NbO, Mo, and W, and other thin films also showed high etching rates.

[0200] Through these results, it was confirmed that the thin film treatment method of the present invention can be effectively applied not only to metal nitride films but also to oxide films and metal films with various transition metals of groups 4 to 6 as central elements. This demonstrates that the present invention is not limited to specific types of thin films but has versatility for a wide range of transition metal-based thin films.

[0201] In particular, it was confirmed that effective etching is possible even in the case of metal films (Mo, W) through a combination of a surface modifier and an etchant. This demonstrates that the method of the present invention is applicable not only to oxide films but also to pure metal films, possessing high versatility for use in various thin film treatments in semiconductor device manufacturing processes.

[0202] In conclusion, the present invention has been confirmed to be an excellent thin film processing technology capable of precise atomic-layer etching and surface treatment for a wide range of transition metal-based thin films, including metal nitride films, metal oxide films, and metal films.

[0203] Although the present invention has been described in detail through embodiments above, other forms of embodiments are also possible. Therefore, the technical concept and scope of the claims described below are not limited to the embodiments.

Claims

Claim 1 A thin film processing method comprising: a step of supplying a surface modifying agent to the interior of a chamber on which a substrate having a thin film formed thereon is placed; a step of purging the interior of the chamber; a step of supplying an etching agent to the interior of the chamber; and a step of purging the interior of the chamber, wherein the etching agent is represented by any one of the following <Chemical Formula 1>, <Chemical Formula 2>, and <Chemical Formula 3>. <Chemical Formula 1> <Chemical Formula 2> In the above <Chemical Formula 1> or <Chemical Formula 2>, X1 to X2 may each be the same or different from each other and are independently selected from hydrogen, a chlorine element, and a chloroalkyl group having 1 to 5 carbon atoms; R1 to R3 may each be the same or different from each other and are independently selected from hydrogen, a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a hydroxyl group having 0 to 4 carbon atoms, and an alkoxy group having 0 to 4 carbon atoms. <Chemical Formula 3> In the above <Chemical Formula 3>, n is each independently selected from integers from 0 to 5, X1 to X3 are each independently selected from an alkoxy group having 1 to 5 carbon atoms and a dialkylamine group having 1 to 5 carbon atoms, and R is selected from hydrogen, a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a dialkylamine group having 1 to 5 carbon atoms. Claim 2 A thin film treatment method according to claim 1, wherein the etching agent is any one of Dichloromethyl methyl ether (DCMME), 1-chloromethyl ethyl ether (1-CMEE), Dimethylformamide dimethyl acetal (DFDA), and Tris(dimethylamino)methane (TDMAM). Claim 3 A thin film treatment method according to claim 1, wherein the method further comprises a method of forming the thin film on the substrate by atomic layer deposition (ALD) prior to the step of supplying the surface modifying agent. Claim 4 A thin film treatment method according to any one of claims 1 to 3, wherein the thin film is a metal nitride thin film having a group 4 metal as a central element. Claim 5 In claim 4, the above-mentioned group 4 metal is any one of Titanium (Ti), Zirconium (Zr), and Hafnium (Hf), a thin film treatment method. Claim 6 A thin film treatment method according to any one of claims 1 to 3, wherein the thin film is a metal nitride thin film having a group 5 metal as a central element. Claim 7 In claim 6, the above Group 5 metal is any one of Vanadium (V), Niobium (Nb), and Tantalum (Ta), a thin film treatment method. Claim 8 A thin film treatment method according to any one of claims 1 to 3, wherein the thin film is a metal film or a metal nitride thin film having a group 6 metal as a central element. Claim 9 In claim 8, the above Group 6 metal is either Molybdenum (Mo) or Tungsten (W), a thin film treatment method. Claim 10 A thin film treatment method according to any one of claims 1 to 3, wherein the surface modifier is any one of O3, O2, H2O, and H2O2. Claim 11 A method for manufacturing a memory device comprising a thin film processing method described in any one of claims 1 to 3.

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