Thin film processing method and method for manufacturing a memory element including the same

Abstract

The present invention provides a thin film processing method for a thin and uniform thickness, and a method for manufacturing a memory element including this method. [Solution] The thin film processing method includes the steps of supplying a surface modifier into a chamber on which a substrate on which a thin film has been formed is placed, purging the inside of the chamber, supplying an etching agent into the chamber, and purging the inside of the chamber.

Description

Technical Field

[0001] <Cross - reference to Related Applications> This application claims priority and benefit to Korean Patent Application No. 10 - 2025 - 0005088, filed on January 13, 2025, and Korean Patent Application No. 10 - 2026 - 0002610, filed on January 7, 2026, the entire disclosure of which is incorporated herein by reference. The present invention relates to a thin - film processing method and a method for manufacturing a memory device including the same, and more particularly, to a method for processing an ultra - fine thin film using a surface modifier and an etchant, and a method for manufacturing a memory device including the same.

Background Art

[0002] As the miniaturization of semiconductor devices accelerates, for metal nitride films that are actively used as electrode materials, electrodes, barriers, liners, or gate electrodes of semiconductor devices, deposition with a thinner and more uniform thickness has become necessary. Related research has been conducted in various aspects, and among them, research on depositing a metal nitride film with island growth to a uniform and thin thickness has attracted attention.

[0003] Due to the island - growth characteristics, metal nitride films generally have a problem that the surface of the thin film is relatively rough. In particular, while the bulk inside the metal nitride film has uniform stability, the surface shows high surface energy, and due to the tendency to maximize internal bonding, the island - growth characteristics are significantly manifested, resulting in a rough surface. Also, since the directionality of the metal bond in the metal nitride film is weak, atomic rearrangement easily occurs, but because the strength of the metal bond is strong, there is a limit in that it easily changes to a crystal phase and the grain size becomes large. Thus, according to the prior art, there is a limit in that metal nitride films have poor surface roughness characteristics and are difficult to deposit thinly, which causes an additional problem of deterioration of interface characteristics during subsequent film deposition.

Summary of the Invention

[0004] On the other hand, conventional atomic layer etching methods have been carried out using etchants such as hydrogen fluoride (HF) and hydrogen chloride (HCl) that easily modify the surface layer due to their strong reactivity. However, while conventional etching methods have the advantage of strong reactivity, they have the problem that the etching rate cannot be precisely controlled by the amount added, or that it is difficult to selectively etch only very thin layers. The amount of etching fluctuates greatly even with minute changes in process conditions, and the etching reaction is not easily self-limiting, making precise etching at the atomic layer level difficult. In addition, because conventional etching agents react non-selectively due to their high reactivity, etching can concentrate locally or occur unevenly, inducing an increase in surface roughness in fine pattern processes for complex structures. Furthermore, because the atoms constituting conventional etching agents (e.g., F, Cl) are very small in size, they can penetrate into undesirable areas below and induce damage, thereby degrading the electrical properties of the device.

[0005] Therefore, there is a need for the development and research of new thin-film processing technologies using novel etching agents that can effectively improve the surface roughness of metal nitride films with island growth characteristics and realize ideal ALE (Atomic Layer Etch), which is the opposite concept of ALD (Atomic Layer Deposition). These technologies maintain a constant thickness etched through the termination of the surface reaction and allow for precise control of the etching rate.

[0006] One object of the present invention is to provide a thin film processing method for a thin and uniform thickness, and a method for manufacturing a memory element including the same.

[0007] One object of the present invention is to provide a thin film processing method that can effectively improve the surface roughness of a metal nitride film having island growth characteristics.

[0008] One objective of the present invention is to provide a thin film processing method that can prevent deterioration of interfacial properties during subsequent film deposition by improving the surface roughness of the metal nitride film.

[0009] One object of the present invention is to provide a thin film processing method that enables uniform etching at the atomic layer level by precisely controlling the etching rate using an etching agent having self-limiting reaction characteristics.

[0010] One objective of the present invention is to provide a thin-film processing method that, unlike conventional highly reactive etching agents, minimizes damage to the lower region through selective and controllable etching, thereby preventing degradation of the electrical characteristics of the device.

[0011] The problems that this invention aims to solve are not limited to those described above, and any problems not mentioned will be clearly understood by a person with ordinary skill in the art to which this invention pertains from this specification and the accompanying drawings. [Means for solving the problem]

[0012] According to one aspect of the present invention, a thin film processing method includes the steps of: supplying a surface modifier to the inside of a chamber on which a substrate on which a thin film has been formed is placed; purging the inside of the chamber; supplying an etching agent to the inside of the chamber; and purging the inside of the chamber, wherein the etching agent is represented by any one of the following chemical formulas: <Chemical Formula 1>, <Chemical Formula 2>, and <Chemical Formula 3>.

[0013] <Chemical formula 1> [ka]

[0014] <Chemical formula 2> [ka]

[0015] In the above-mentioned <Chemical Formula 1> or <Chemical Formula 2>, X1 to X2 may be the same as or different from each other, and are independently selected from hydrogen, chlorine, and a chloroalkyl group having 1 to 5 carbon atoms. R1 to R3 may be the same as 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.

[0016] <Chemical formula 3> [ka]

[0017] In the above-mentioned <Chemical Formula 3>, n is independently selected from integers 0 to 5, X1 to X3 are independently selected from alkoxy groups having 1 to 5 carbon atoms and dialkylamino groups having 1 to 5 carbon atoms, and R is selected from hydrogen, linear, branched, or cyclic alkyl groups having 1 to 5 carbon atoms, alkoxy groups having 1 to 5 carbon atoms, and dialkylamino groups having 1 to 5 carbon atoms.

[0018] The etching agent may be any one of the following: dichloromethyl methyl ether (DCMME), 1-chloromethyl ethyl ether (1-CMEE), dimethylformamide dimethyl acetal (DFDA), or tris(dimethylamino)methane (TDMAM).

[0019] The above method may further include a step of forming the thin film on the substrate by atomic layer deposition (ALD) before the step of supplying the surface modifier.

[0020] The thin film may be a metal nitride thin film with a group 4 metal as the central element.

[0021] The Group 4 metal may be any one of titanium (Ti), zirconium (Zr), and hafnium (Hf).

[0022] The thin film may be a metal nitride thin film having a Group 5 metal as a central element.

[0023] The Group 5 metal may be any one of vanadium (V), niobium (Nb), and tantalum (Ta).

[0024] The thin film may be a metal film or a metal nitride thin film having a Group 6 metal as a central element.

[0025] The Group 6 metal may be any one of molybdenum (Mo) and tungsten (W).

[0026] The surface modifier may be any one of O3, O2, H2O, and H2O2.

[0027] According to one aspect of the present invention, a method for manufacturing a memory device may include the thin film processing method described above.

[0028] The solution to the problems of the present invention is not limited to the solutions described above, and solutions not mentioned will be clearly understood by those having ordinary knowledge in the technical field to which the present invention pertains from this specification and the accompanying drawings.

[0029] According to the thin film processing method according to one aspect of the present invention, a thin film having a thin and uniform thickness can be formed using a surface modifier and an etching agent.

Effects of the Invention

[0030] According to the thin film processing method according to one aspect of the present invention, the etching rate can be precisely controlled using an etching agent having self-limiting reaction characteristics. This solves the difficulty of controlling the etching rate that conventional highly reactive etching agents had and enables precise thickness control in atomic layer units.

[0031] According to one aspect of the present invention, the thin film processing method can be effectively applied not only to metal nitride films but also to oxide films and metal films with various transition metals from Group 4 to Group 6 as central elements, providing versatility that can be utilized in a wide range of semiconductor device manufacturing processes.

[0032] The effects of the present invention are not limited to those described above, and any effects not mentioned herein will be clearly understood by a person skilled in the art to which the present invention pertains from this specification and the accompanying drawings. [Brief explanation of the drawing]

[0033] [Figure 1] Figure 1 shows a thin film processing method according to an embodiment of the present invention. [Figure 2] Figure 2 is a schematic graph showing the supply cycle according to an embodiment of the present invention. [Figure 3] Figure 3 is a graph that schematically shows the supply cycle for the comparative example. [Figure 4] Figure 4 shows the thickness and roughness of the TiN thin film before etching, in a comparative example, and in Experimental Example 1. [Figure 5] Figure 5 shows the thickness and roughness of the TiN thin film before etching, in a comparative example, and in Experimental Example 1. [Figure 6] Figure 6 shows the thickness and roughness of the TiN thin film before etching, in the comparative example, and in Experimental Example 1. [Figure 7] Figure 7 is a graph analyzing the thickness of the thin film according to the presence or absence of etching agent supply at different process temperatures in Experimental Example 2. [Figure 8] Figure 8(a) is a graph showing the EPC according to the number of cycles for Experimental Example 3. Figure 8(b) is a graph showing the EPC according to the amount of etching agent supplied for Experimental Example 3. [Figure 9] Figure 9 shows the thickness and roughness of the TiN thin film before and after etching in Experimental Example 4. [Figure 10]Figure 10 shows the thickness and roughness of the TiN thin film before and after etching in Experimental Example 5. [Figure 11] Figure 11(a) is a graph showing the EPC according to the number of cycles for Experimental Example 6. Figure 11(b) is a graph showing the EPC according to the amount of etching agent supplied for Experimental Example 6. [Figure 12] Figure 12 is a graph showing the thickness of the thin film according to the number of cycles for each metal nitride film in Experimental Example 7. [Figure 13] Figure 13 is a graph showing the change in thin film thickness in response to etching. [Modes for carrying out the invention]

[0034] The above-mentioned objectives, features, and advantages of the present invention will become clearer through the following detailed description in conjunction with the accompanying drawings. However, since the present invention can be modified in various ways and may have multiple embodiments, specific embodiments are illustrated in the drawings and described in detail below.

[0035] Throughout the specification, the same reference numerals generally indicate the same components. Furthermore, components with the same function within the same conceptual scope, as shown in the drawings of each embodiment, are described using the same reference numerals, and redundant descriptions are omitted.

[0036] Where a specific description of a known function or configuration related to the present invention is deemed likely to unnecessarily obscure the gist of the invention, such detailed description will be omitted. Furthermore, the numbers used in the description herein (e.g., 1st, 2nd, etc.) are merely identification symbols to distinguish one component from another.

[0037] In the following embodiments, a singular expression includes plural expressions unless the meaning is clearly different in context.

[0038] In the following embodiments, terms such as "includes" or "has" mean that the features or components described in the specification exist, and do not preclude the possibility that one or more other features or components may be added.

[0039] In drawings, the size of components may be exaggerated or reduced for the sake of illustration. For example, the size and thickness of each component shown in the drawings are arbitrarily shown for the sake of illustration, and the present invention is not necessarily limited to those shown.

[0040] Where a particular embodiment can be implemented in a different way, the order of a particular process may be different from the order described. For example, two processes described consecutively may be performed substantially simultaneously and may proceed in the reverse order of the description.

[0041] This invention relates to a method for depositing thin films, particularly metal nitride films, with a uniform and thin thickness using island growth. Island growth refers to the growth of thin films in island form when deposited on a substrate. Thin films grown in island form generally have a rough surface, making it difficult to deposit fine thin films.

[0042] The present invention relates to a method for making an island-grown thin film into a thin and uniform thin film through an atomic layer etching (ALE) process, wherein the surface roughness of the thin film can be improved through the atomic layer etching process.

[0043] The principle by which surface roughness is improved by this invention is as follows: Protruding portions on the surface have higher surface energy and a wider exposed area than flat portions. Also, because they are less affected by surrounding atoms, when a surface modifier is applied, modification proceeds more in the protruding portions than in the non-protruding portions. Conversely, in recessed portions on the surface have lower surface energy due to their reverse curvature and are more affected by surrounding atoms, resulting in less modification. The more modification has progressed in a given area, the more etching occurs when the etching agent is applied, and the more the protruding portion gradually decreases. Therefore, surface roughness can be improved by performing an atomic layer etching (ALE) process on a thin film.

[0044] The thin film processing method according to the present invention will be described in more detail below with reference to Figures 1 to 13.

[0045] Figure 1 is a diagram showing a thin film processing method according to an embodiment of the present invention, and Figure 2 is a graph schematically showing a supply cycle according to an embodiment of the present invention. The substrate is loaded into the process chamber and 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 process chamber, or the substrate may be loaded into the process chamber after the thin film has been formed.

[0046] For 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.

[0047] Thin films can be deposited through island growth during their formation process.

[0048] According to one embodiment, the thin film may be a metal nitride thin film, a metal oxide thin film, and / or a metal film with a Group 4 metal as the central element, and may have one of Ti, Zr, and Hf as the central element.

[0049] According to one embodiment, the thin film may be a metal nitride thin film, a metal oxide thin film, and / or a metal film with a Group 5 metal as the central element, and may have one of V, Nb, and Ta as the central element.

[0050] According to one embodiment, the thin film may be a metal nitride thin film, a metal oxide thin film, and / or a metal film with a group 6 metal as the central element, and may have one of Mo and W as the central element.

[0051] On the other hand, the following process conditions can be adjusted. Process conditions may include the temperature of the substrate or process chamber, chamber pressure, and gas flow rate.

[0052] Referring again to Figures 1 and 2, the substrate may be exposed to a surface modifier supplied into the chamber, and the surface modifier may be one of O3, O2, H2O, and H2O2. The surface modifier can react with a thin film, especially a metal nitride film, to modify the surface of the metal nitride film. In this case, as mentioned above, the protruding portion due to island growth has a higher surface energy and is more reactive than the surrounding portion, and because of its high curvature it is relatively unaffected by surrounding atoms, the possibility of collision with the surface modifier increases, and it can react with the surface modifier relatively more.

[0053] After the surface modifier is supplied, a purge gas (e.g., an inert gas such as nitrogen (N2), argon (Ar), and / or helium (He)) may be supplied to the inside of the chamber to remove or purify any unreacted substances or by-products.

[0054] After supplying the surface modifier (preferably after supplying the surface modifier and purge gas), an etching agent may be supplied into the chamber, and the thin film (metal nitride film) modified through the surface modifier may be exposed to the etching agent. Since the protruding portions of the thin film modified through the surface modifier have a lower film density than the non-protruding portions, the reaction with the etching agent proceeds relatively well, and etching can be carried out relatively more. Through this, the surface roughness of the protruding portions of the metal nitride film can be improved.

[0055] An etching agent according to one embodiment may be represented by <Chemical Formula 1> or <Chemical Formula 2>.

[0056] <Chemical formula 1> [ka]

[0057] <Chemical formula 2> [ka]

[0058] In the above-mentioned <Chemical Formula 1> or <Chemical Formula 2>, X1 to X2 may be the same as or different from each other, and are independently selected from hydrogen, chlorine, and a chloroalkyl group having 1 to 5 carbon atoms. R1 to R3 may be the same as or different from each other, and can be 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, or an alkoxy group having 0 to 4 carbon atoms.

[0059] According to one embodiment, the etching initiator (or etching agent) may be either dichloromethyl methyl ether (DCMME) or 1-chloromethyl ethyl ether (1-CMEE).

[0060] Alternatively, the etching agent may be represented by <Chemical Formula 3>.

[0061] <Chemical formula 3> [ka]

[0062] In the above-mentioned <Chemical Formula 3>, n is independently selected from integers 0 to 5, X1 to X3 are independently selected from alkoxy groups having 1 to 5 carbon atoms and dialkylamino groups having 1 to 5 carbon atoms, and R can be selected from hydrogen, linear, branched, or cyclic alkyl groups having 1 to 5 carbon atoms, alkoxy groups having 1 to 5 carbon atoms, and dialkylamino groups having 1 to 5 carbon atoms.

[0063] Specifically, the etching agent may be either Dimethylformamide dimethyl acetal (DFDA) or Tris(dimethylamino)methane (TDMAM).

[0064] Referring again to Figure 2, after the etching agent has been supplied, a purge gas (e.g., an inert gas such as Ar) may be supplied to the inside of the chamber to remove or purify any unreacted substances or by-products.

[0065] According to one embodiment of the present invention, the source for the ALE process may be supplied via a Liquid Flow Meter (LFM) system. The LFM system quantitatively measures the liquid source and supplies it to a vaporizer, which then vaporizes it and introduces it into the reaction chamber. Specifically, the liquid source is precisely controlled at a preset flow rate via a flow meter (LFM), and the source may be instantaneously vaporized in a heated vaporizer, mixed with a carrier gas, and then supplied into the process chamber.

[0066] According to one embodiment of the present invention, the source for the ALE process may be supplied via a vaporization method. The vaporization method involves heating the source in a storage container (canister) to vaporize it, and then supplying the vapor directly to the reaction chamber. Specifically, the source is naturally vaporized in a storage container maintained at a predetermined temperature, and the generated source vapor is transferred to the reaction chamber by a carrier gas or pressure difference. In this case, the amount of source supplied may be determined mainly by the vapor pressure of the source, the temperature of the storage container, 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 of a metering valve located on the supply line. [Examples]

[0067] The configuration and effects of the present invention will be described in more detail below with reference to specific examples. However, these examples are merely intended to make the present invention easier to understand and do not intend to limit the scope of the present invention.

[0068] (1) Example 1 - Comparative Example A substrate with island-grown thin film (TiN) was prepared, and after measuring the thickness and roughness of the thin film, etching was carried out using an etching agent without using a surface modifier. The etching agent used was 1-chloromethyl ethyl ether (1-CMEE) (shown as <Chemical Formula 4> below), and the etching was carried out at a process temperature of 300°C.

[0069] <Chemical formula 4> [ka]

[0070] Figure 3 is a graph that schematically shows the supply cycle for the comparative example.

[0071] The etching process was repeated 50 times, with the following steps considered as one cycle, as shown in Figure 3.

[0072] 1) Supply the etching agent (1-CMEE) into the reaction chamber. 2) Supply a purge gas (Ar gas) into the reaction chamber to remove unreacted substances or by-products. This comparative example was conducted to illustrate the condition in which the ALE process cannot be performed when only an etching agent is used.

[0073] - Experimental Example 1 A substrate with island-grown thin films (TiN) was prepared, and etching was carried out by sequentially supplying a surface modifier and an etching agent. O3 was used as the surface modifier, and 1-chloromethyl ethyl ether (1-CMEE) was used as the etching agent. The etching was carried out at a process temperature of 300°C.

[0074] The etching process was repeated 50 times, with the following steps forming one cycle, as shown in Figure 2.

[0075] 1) Supply the surface modifier (O3) into the reaction chamber. 2) Supply a purge gas (Ar gas) into the reaction chamber to remove unreacted substances or by-products. 3) Supply the etching agent (1-CMEE) into the reaction chamber. 4) Supply a purge gas (Ar gas) into the reaction chamber to remove unreacted substances or by-products. Figures 4 to 6 show the thickness and roughness of the TiN thin film before 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).

[0076] Figures 4 and 5 show that when no surface modifier was used, the thickness due to etching decreased by approximately 0.6 angstroms, from 98.9 angstroms (the thickness before etching) to 98.3 angstroms. This small decrease means that the Rq value for roughness did not improve from 0.4 nm (the Rq value before etching) to 0.39 nm, thus confirming that the ALE process was not successful. The changes in thin film thickness and Rq value shown in Figures 4 and 5 fall within the measurement error range, indicating that the decrease was negligible.

[0077] On the other hand, Figures 4 and 6 show that the thickness of the thin film decreased by approximately 30 angstroms, from 98.9 angstroms (the thickness before etching) to 70.9 angstroms, and the Rq value (Root Mean Square roughness; a lower value indicates a more uniform surface) decreased from 0.4 nm (the Rq value before etching) to 0.37 nm, indicating a relatively significant improvement in roughness. Referring to the TEM data, it was confirmed that the roughness had improved to a degree that was visible to the naked eye.

[0078] Poor surface roughness can lead to differences in electrical properties between thin and thick areas of the thin film. In particular, as semiconductor devices become smaller, the absolute thickness of the thin film decreases, resulting in larger relative thickness deviations that can negatively impact the performance uniformity and reliability of the device. Therefore, improving surface roughness ensures uniformity of the thin film thickness, thereby improving the quality of the interface formed in subsequent processes and improving the electrical properties and yield of the device. These results demonstrate the necessity of a surface modifier in the etching process of TiN thin films, and it was confirmed that the ALE process is feasible with the application of a surface modifier.

[0079] (2) Example 2 - Experimental Example 2 (Evaluation of etching characteristics by temperature) In Experimental Example 2, 1-chloromethyl ethyl ether (1-CMEE) was used as the etching agent, and the etching characteristics with respect to temperature were confirmed by etching a TiN thin film in a process temperature range of 300°C to 380°C.

[0080] The source was cyclically fed into the chamber according to the supply cycle shown in Figure 2, and O3 was used as the surface modifier. After 50 cycles of the etching process at temperatures 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 etching agent (60 seconds) → supplying the purge gas (30 seconds) was considered one cycle and repeated 50 times. Ar gas was used as the purge gas during this process.

[0081] Furthermore, to compare with the case where no surface modifier was used, the etching agent (1-CMEE) was cyclically fed without supplying the surface modifier, according to the supply cycle shown in Figure 3. Similarly, after performing 50 etching cycles at temperatures of 300°C, 340°C, and 380°C, the change in thin film thickness was measured. Specifically, in the case where no surface modifier was used, the process of supplying the etching agent (60 seconds) → supplying the purge gas (30 seconds) was considered one cycle and repeated 50 times. Ar gas was used as the purge gas in this case.

[0082] Figure 7 is a graph analyzing the thickness of the thin film according to the presence or absence of etching agent supply at different process temperatures in Experimental Example 2.

[0083] Referring to Figure 7, when only the etching agent was repeatedly applied without the use of a surface modifier, almost no etching occurred in all temperature ranges, and the change in thin film thickness was close to zero. On the other hand, when the surface modifier was used, a decrease in thin film thickness of approximately 10 angstroms was observed at 300°C, approximately 20 angstroms at 340°C, and approximately 45 angstroms at 380°C. This indicates that the thin film thickness decreases linearly as the process temperature increases.

[0084] These results confirmed that thin films at the atomic layer level can be uniformly etched through a surface reaction between the surface modifier and the etching agent, and that the etching rate can be controlled by adjusting the process temperature. Furthermore, it was reaffirmed that the use of a surface modifier is essential for the ALE process to function.

[0085] The principle by which etching performance is improved when surface modifiers are 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, changing the chemical bonding state and composition of the surface. Nitride film surfaces mainly have a bonding structure containing nitrogen species or -NH terminals, but oxygen species bonded by the oxidizing agent are more reactive than nitrogen species, facilitating the initiation of the reaction in the subsequent etching step. For example, in the case of a TiN thin film, surface oxidation may proceed with a reaction equation such as TiN(s) + 3O3(g) → TiO2(s) + NO(g) + 3O2(g), and through this, the surface after the modification step can be converted to a state more suitable for etching.

[0086] Furthermore, in the modification process using an oxidizing agent-type surface modifier, the oxidation state of the center metal in the underlying metal film or metal nitride film increases due to bonding with oxygen. This increase in oxidation state reduces the electron density of the center metal, which can promote the reaction with the subsequent etching agent. The important point is that this modification step alters only the outermost surface region of the film to be etched, and in subsequent processes, only the modified surface layer participates in the etching reaction, thereby maintaining the self-limiting properties of the ALE process.

[0087] - Experimental Example 3 (EPC Evaluation) In Experimental Example 3, a TiN thin film was etched at a process temperature of 300°C using 1-chloromethyl ethyl ether (1-CMEE) as the etching agent and O3 as the surface modifier. Similar to Experimental Example 1, the etching process was repeatedly performed according to the supply cycle shown in Figure 2, and the change in EPC (Etch Per Cycle) with respect to the number of cycles and / or the amount of etching agent supplied was evaluated. Specifically, the process of supplying the surface modifier (3 seconds) → supplying the purge gas (15 seconds) → supplying the etching agent (60 seconds) → supplying the purge gas (30 seconds) was considered one cycle and repeated several times at a process temperature of 300°C. Ar gas was used as the purge gas.

[0088] First, to confirm the stability of the etching rate with respect to the number of cycles, the etching process was carried out for up to 60 cycles, and the source was supplied into the chamber at 0.1 g / min via the LFM method.

[0089] Figure 8(a) is a graph showing the EPC (Engineering Process Control) corresponding to the number of cycles for Experimental Example 3.

[0090] While the initial cycle showed a relatively high EPC value, it decreased as the number of cycles increased up to 30, and then remained at a virtually constant level up to 60 cycles. This means that the EPC is stably maintained even when the number of cycles is increased after 30 cycles, confirming that the etching process proceeds through the atomic layer etching method and that the etching rate can be precisely controlled.

[0091] Furthermore, to evaluate the saturation characteristics based on the etching agent supply rate, EPC was measured while varying the metering valve opening value. The source was supplied via a vapor method.

[0092] Figure 8(b) is a graph showing the EPC (Engineering Procurement Cost) according to the amount of etching agent supplied for Experimental Example 3.

[0093] When the metering valve opening was 0, no etching occurred, and EPC increased linearly as the supply rate increased. Subsequently, it was confirmed that at a supply rate above a certain level (metering valve opening: approximately 1.0), EPC converged to a nearly constant value and reached the saturation region. This indicates that when the etching agent supply rate increases sufficiently, the surface reaction saturates and the etching rate does not increase any further.

[0094] These results confirm that the etching process of the present invention proceeds as an atomic layer etching method with self-limiting properties, ensuring process reproducibility and uniformity in the saturation region. This means that, unlike conventional highly reactive etchants (etchants such as HCl and HF), the present invention allows for precise control of the etching rate for thin films.

[0095] (3) Example 3 - Experimental Example 4 (Thickness and Rq Evaluation) 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 etching agent. The supply cycle (1 cycle) shown in Figure 2 was repeated 60 times. Specifically, the process of supplying the surface modifier (3 seconds) → supplying the purge gas (15 seconds) → supplying the etching agent (60 seconds) → supplying the purge gas (30 seconds) was considered one cycle and repeated 60 times at a process temperature of 300°C. 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.

[0096] Figure 9 shows the thickness and surface roughness of the TiN thin film before and after etching for Experimental Example 4. Specifically, Figure 9(a) shows the thickness and surface roughness of the TiN thin film before etching for Experimental Example 4, and Figure 9(b) shows the thickness and surface roughness of the TiN thin film after etching for Experimental Example 4.

[0097] TEM / AFM analysis revealed that the thin film thickness before the ALE process was 187.4 angstroms (=18.74 nm), with a Root Mean Square Rq (Rq) value of 0.80 nm. After the ALE process, the thin film thickness decreased to 157.9 angstroms (=15.79 nm), a reduction of approximately 29.5 angstroms. Furthermore, the Rq value decreased to 0.59 nm, indicating a 26% improvement in surface roughness.

[0098] Furthermore, a visual comparison of TEM images revealed that while surface irregularities were clearly visible on the upper surface of the thin film before the ALE process, the surface became relatively flatter and more 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.

[0099] These results confirm that the atomic layer etching (ALE) process using the surface modifier and etching agent of the present invention can precisely reduce the thickness of the metal nitride film while simultaneously improving surface roughness. This can contribute to improving interfacial properties during subsequent film deposition.

[0100] (4) Example 4 (Etching agent: Dimethylformamide Dimethyl Acetal (DFDA) used) In Example 4, etching was performed by substituting the etching agent (1-chloromethyl ethyl ether (1-CMEE)) used in Examples 2 and 3 with the methylformamide dimethyl acetal (DFDA) etching agent.

[0101] - Experimental Example 5 (Evaluation of Thickness and Roughness) 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 etching agent. The process temperature was set to 340°C, and the etching process was carried out by repeating the supply cycle (1 cycle) shown in Figure 2 60 times. Specifically, the process of supplying the surface modifier (3 seconds) → supplying the purge gas (15 seconds) → supplying the etching agent (60 seconds) → supplying the purge gas (30 seconds) was considered one cycle and repeated 60 times at a process temperature of 340°C. Ar gas was used as the purge gas in this process.

[0102] To confirm the cross-sectional structure and surface roughness changes of the thin film, transmission electron microscopy (TEM) analysis and atomic force microscopy (AFM) analysis were performed before and after the ALE process.

[0103] Figure 10 shows the thickness and surface roughness of the TiN thin film before and after etching for Experimental Example 5. Specifically, Figure 10(a) shows the thickness and surface roughness of the TiN thin film before etching for Experimental Example 5, and Figure 10(b) shows the thickness and surface roughness of the TiN thin film after etching for Experimental Example 5.

[0104] TEM and AFM analysis results showed that the thickness of the thin film before the ALE process was measured at 187.4 angstroms (=18.74 nm), with a Rq (Root Mean Square roughness) value of 0.80 nm. After the ALE process, the thickness of the thin film decreased to 161.7 angstroms (=16.17 nm), a reduction of approximately 25.7 angstroms. Furthermore, the Rq value decreased to 0.60 nm, confirming a 25% improvement in surface roughness.

[0105] Furthermore, a visual comparison of TEM images revealed that while surface irregularities were clearly visible on the upper surface of the thin film before the ALE process, the surface became relatively flatter and more uniform after the ALE process. This visually demonstrates that even when using the "DFDA etching agent," the atomic layer etching process can effectively improve surface roughness by selectively removing protruding parts of the surface.

[0106] These results confirm that, when using not only the 1-CMEE etching agent of the present invention but also the DFDA etching agent, the thickness of the metal nitride film can be precisely reduced while simultaneously improving the surface roughness through combination with a surface modifier. Furthermore, this demonstrates that various etching agents having a structure similar to 1-CMEE or DFDA can be applied to the thin-film processing according to the present invention.

[0107] - Experimental Example 6 (EPC Evaluation) In Experimental Example 6, a TiN thin film was etched at a process temperature of 340°C using "Dimethylformamide Dimethyl Acetal (DFDA)" as the etching agent and O3 as the surface modifier. The etching process was repeatedly performed according to the supply cycle shown in Figure 2, and the change in EPC (Etch Per Cycle) with respect to the number of cycles and / or the amount of etching agent supplied was evaluated. Specifically, the process of supplying the surface modifier (3 seconds) → supplying the purge gas (15 seconds) → supplying the etching agent (60 seconds) → supplying the purge gas (30 seconds) was considered one cycle and was repeated several times at a process temperature of 340°C. Ar gas was used as the purge gas.

[0108] First, to confirm the stability of the etching rate with respect to the number of cycles, the etching process was carried out for up to 60 cycles, and the source was supplied into the chamber at 0.1 g / min via the LFM method.

[0109] Figure 11(a) is a graph showing the EPC (Engineering Process Control) corresponding to the number of cycles for Experimental Example 6.

[0110] While the initial cycle showed a relatively high EPC value, the EPC decreased until 30 cycles, and then remained stably at a substantially constant level until 60 cycles. This means that the EPC remains stably maintained even when the number of cycles is increased after 30 cycles, confirming that even when using DFDA etchants, the etching process proceeds through atomic layer etching, allowing for precise control of the etching rate.

[0111] Furthermore, to evaluate the saturation characteristics depending on the supply amount of etching agent, EPC was measured while varying the LFM (Liquid Flow Meter) flow value.

[0112] Figure 11(b) is a graph showing the EPC (Engineering Procurement Cost) according to the amount of etching agent supplied for Experimental Example 6.

[0113] It was confirmed that no etching occurred when there was no etchant supply (LFM Flow = 0 g / min), and that EPC increased linearly as the supply amount increased. Subsequently, it was confirmed that at a supply amount above a certain level (LFM Flow: supply amount of approximately 0.02 g / min or more), EPC converged to a substantially constant value and reached the saturation region. This indicates that when the etchant supply amount increases sufficiently, the surface reaction saturates and the etching rate does not increase any further.

[0114] These results confirm that the atomic layer etching method exhibits self-limiting properties not only when using the 1-CMEE etching agent of the present invention but also when using the DFDA etching agent, ensuring process reproducibility and uniformity in the saturation region. Furthermore, it was demonstrated that various etching agents having structures similar to 1-CMEE or DFDA (i.e., etching agents according to chemical formulas 1 to 3 (e.g., Dichloromethyl methyl ether (DCMME), Tris(dimethylamino)methane (TDMAM))) can be applied to the thin film processing according to the present invention, and that, unlike conventional highly reactive etching agents (HCl, HF), the etching rate of the thin film can be precisely controlled.

[0115] (5) Example 5 (Etching evaluation by metal nitride film) - Experimental Example 7 (Evaluation of Thickness Change) In Experimental Example 7, TiN, TiSiN, and MoN thin films were etched at a process temperature of 340°C using dichloromethyl methyl ether (DCMME) as the etching agent and O3 as the surface modifier.

[0116] The source was cyclically fed into the chamber according to the supply cycles shown in 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. The etching process was performed for each thin film up to a maximum of 100 cycles. Specifically, in Experimental Example 7, the process of supplying the surface modifier (3 seconds) → supplying the purge gas (15 seconds) → supplying the etching agent (10 seconds) → supplying the purge gas (10 seconds) was considered one cycle and was repeated several times at a process temperature of 340°C. Ar gas was used as the purge gas.

[0117] Figure 12 is a graph showing the thickness of the thin film according to the number of cycles for each metal nitride film in Experimental Example 7.

[0118] When only the etching agent was repeatedly applied without using a surface modifier, it was confirmed that the thin film thickness hardly decreased even as the number of cycles increased for all TiN, TiSiN, and MoN thin films, and that etching did not occur. In other words, it was confirmed that the ALE process is not feasible without the use of a surface modifier.

[0119] On the other hand, when a surface modifier was used, the film thickness decreased linearly with increasing cycle count for all thin films (TiN, TiSiN, MoN). Specifically, in the case of the TiN thin film, starting from an initial thickness of approximately 75 angstroms, it was almost completely etched after 30 cycles, with an etching rate measured at 2.27 angstroms / cycle. Similarly, in the case of the MoN thin film, starting from an initial thickness of approximately 60 angstroms, it was almost completely etched after 30 cycles, with an etching rate measured at 1.84 angstroms / cycle. In the case of the TiSiN thin film, starting from an initial thickness of approximately 130 angstroms, it gradually decreased at a relatively slow rate, with an etching rate measured at 0.28 angstroms / cycle, showing a relatively low etching rate compared to the other thin films.

[0120] These results reaffirmed that the sequential surface reaction between the surface modifier and the etching agent is essential for effective atomic layer etching. Furthermore, it was confirmed that the thin-film treatment method according to the present invention can be applied not only to 1-CMEE and DFDA etching agents, but also to DCMME etching agents.

[0121] Furthermore, it was confirmed that the thin-film processing method according to the present invention enables precise etching at the atomic layer level for various metal nitride films such as TiN, TiSiN, and MoN. The etching rate varied depending on the type of thin film, indicating its applicability to selective etching processes. In particular, it was confirmed that rapid thin-film removal was possible with high etching rates for TiN and MoN, while more precise thickness control was possible with relatively lower etching rates for TiSiN. This demonstrates the versatility of the thin-film processing method according to the present invention, applicable to a variety of metal nitride films.

[0122] Through the aforementioned Experimental Examples 1 to 7, it was confirmed that a thin, uniformly thick metal nitride film can be formed in an atomic layer etching (ALE) process using the surface modifier and etching agent of the present invention. In particular, it was confirmed that the use of the surface modifier is essential for effective etching, and that the etching agents represented by chemical formulas 1, 2, and 3 of the present invention have self-limiting properties, enabling precise etching at the atomic layer level. Furthermore, it was confirmed that the invention is applicable not only to TiN but also to a variety of metal nitride films such as TiSiN and MoN.

[0123] The thin film processing method of the present invention can provide the following effects.

[0124] Firstly, surface roughness can be effectively improved. As confirmed in Experimental Examples 4 and 5, the surface roughness (Rq) decreased by 25-26% through the atomic layer etching process compared to before etching. This means that protruding parts of the thin film surface were selectively removed, resulting in a planar surface. This improvement in surface roughness can improve interfacial properties during subsequent film deposition, thereby improving the electrical characteristics and reliability of the device.

[0125] Secondly, 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. After a certain number of cycles, the EPC stabilized and showed a self-limiting characteristic, reaching the saturation region when the amount of etchant supplied was increased. This solves the difficulty in controlling the etching rate that existed with conventional highly reactive etchants such as hydrogen fluoride (HF) and hydrochloric acid (HCl), and means that precise thickness control at the atomic layer level is possible.

[0126] Thirdly, the reproducibility and uniformity of the process can be ensured. As confirmed in Experimental Examples 3 and 6, since the etching reaction is maintained constant in the saturation region, the amount of etching does not fluctuate significantly even with slight changes in process conditions, ensuring high reproducibility. Furthermore, due to the self-limiting reaction characteristics, uniform etching is possible even in the process of creating fine patterns of complex structures, preventing localized etching concentrations or non-uniformity.

[0127] Fourthly, damage to the lower region can be minimized. Unlike conventional etching agents such as HCl and HF, the etching agent of the present invention does not penetrate to the lower region and induce damage, and can precisely etch only the desired region through a selective and controllable surface reaction. This prevents deterioration of the electrical characteristics of the device and improves the reliability of the device.

[0128] Fifth, it possesses versatility applicable to a variety of metal nitride films. As confirmed in Experimental Example 7, it enables effective etching of 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 used in various semiconductor device manufacturing processes.

[0129] In conclusion, the thin-film processing method of the present invention has been confirmed to overcome the limitations of the prior art and is an excellent technology that can simultaneously achieve precise thin-film thickness control, surface roughness improvement, and process reproducibility, which are necessary for the manufacturing process of miniaturized semiconductor devices.

[0130] (6) Example 6 (Evaluation of applicability of transition metal films) - Experimental Example 8 To confirm whether the thin-film processing method of the present invention is applicable to a variety of transition metal thin films, etching experiments were conducted on oxide films and / or metal films with group 4 metal elements (Ti, Hf), group 5 metal elements (Nb, Ta), and group 6 metal elements (Mo, W) as the central elements.

[0131] Specifically, TiO, NbO, TaO, and HfO oxide films and Mo and W metal films were prepared by depositing them on a substrate. O3 was used as the surface modifier for each thin film, and dichloromethyl methyl ether was used as the etching agent. The process temperature was set to 300°C, and the process consisted of supplying the surface modifier, purging, supplying the etching agent, and purging, as shown in Figure 2, with each cycle being repeated until each thin film was sufficiently etched. On the other hand, in the case of oxide films, the supply of the surface modifier could be omitted, and etching was performed using the etching agent on the oxide film formed with the oxidizing agent.

[0132] Table 1 below shows the thickness of the thin film before and after etching, and Figure 13 is a graph showing the change in the thickness of the thin film in response to etching.

[0133] [Table 1] [Table 1]

[0134] As shown in Table 1 and Figure 13, it was confirmed that etching proceeded effectively in all transition metal thin films.

[0135] Specifically, in the case of Group IV metal oxide films, TiO was almost completely etched, decreasing by approximately 95.6% from an initial thickness of 107.56 angstroms to 4.76 angstroms, while HfO decreased by approximately 63.2% from an initial thickness of 53.84 angstroms to 19.8 angstroms.

[0136] In the case of Group 5 metal oxide films, NbO was completely etched down from an initial thickness of 52.95 angstroms to 0 angstroms, while TaO was reduced by approximately 75.7%, from an initial thickness of 51.02 angstroms to 12.42 angstroms.

[0137] For Group 6 metals, the Mo metal film was almost completely etched, decreasing by approximately 98.8% from an initial thickness of 140.12 angstroms to 1.68 angstroms, while the W metal film was completely etched from an initial thickness of 102.23 angstroms to 0 angstroms.

[0138] Visual confirmation through Figure 13 revealed that in all thin films, the considerable thickness before the process was significantly reduced or almost completely removed after the process. In particular, NbO, Mo, and W demonstrated that almost complete etching was possible, and the other thin films also showed high etching rates.

[0139] These results confirm that the thin-film processing 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 from Group 4 to Group 6 as central elements. This demonstrates that the present invention is not limited to a specific form of thin film but has versatility for a wide range of transition metal-based thin films.

[0140] 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 etching agent. This indicates that the method of the present invention is applicable not only to oxide films but also to pure metal films, and has high versatility that can be utilized in various thin-film processing in semiconductor device manufacturing processes.

[0141] 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 of a wide range of transition metal-based thin films, including metal nitride films, metal oxide films, and metal films.

[0142] The features, structures, and effects described in the exemplary embodiments described above are included in at least one exemplary embodiment of the present invention, but are not necessarily limited to just one exemplary embodiment. Furthermore, the features, structures, and effects exemplified in each embodiment can be combined or modified and implemented in other embodiments by a person with ordinary skill in the art to which the embodiment belongs. Therefore, the content related to such combinations and modifications should be interpreted as being included within the scope of the present invention.

[0143] Furthermore, although the present invention has been described in particular with reference to examples, these examples are merely illustrative embodiments of the present invention and are not intended to limit the present invention thereto. Those with ordinary skill in the art to which the present invention pertains will understand that other forms of modification and application are possible without departing from the spirit and scope of the invention. That is, each element specifically shown in the examples may be modified and implemented. Furthermore, any differences related to these modifications and applications should be understood to fall within the scope of the present invention as defined in the appended claims.

Claims

1. A step of supplying a surface modifier into the chamber on which a substrate with a thin film formed on it is placed; A step of purging the inside of the chamber; A step of supplying an etching agent to the inside of the chamber; and includes the step of purging the inside of the chamber, The etching agent is represented by one of the following chemical formulas: <Chemical Formula 1>, <Chemical Formula 2>, or <Chemical Formula 3>, and is used for thin film treatment. <Chemical formula 1> 【Chemistry 1】 <Chemical formula 2> 【Chemistry 2】 In the above-mentioned <Chemical Formula 1> or <Chemical Formula 2>, X １ ~X ２ Each of these may be the same or different from the others, and is independently selected from hydrogen, a chlorine atom, and a chloroalkyl group having 1 to 5 carbon atoms, R １ ~R ３ Each of these may be the same as or different from the others, and can be 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, or an alkoxy group having 0 to 4 carbon atoms. <Chemical formula 3> 【Transformation 3】 In the above-mentioned <Chemical Formula 3>, n is independently selected from integers between 0 and 5, and X １ ~X ３ Each of the following is independently selected from an alkoxy group having 1 to 5 carbon atoms and a dialkylamino 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 dialkylamino group having 1 to 5 carbon atoms.

2. The thin film treatment method according to claim 1, wherein the etching agent is one of Dichloromethyl methyl ether (DCMME), 1-chloromethyl ethyl ether (1-CMEE), Dimethylformamide dimethyl acetal (DFDA), or Tris (dimethylamino)methane (TDDMA).

3. The thin film treatment method according to claim 1, further comprising a step of forming the thin film on the substrate by atomic layer deposition (ALD) before the step of supplying the surface modifier.

4. The thin film treatment method according to claim 1, wherein the thin film is a metal nitride thin film with a group IV metal as the central element.

5. The thin film treatment method according to claim 4, wherein the Group 4 metal is one of titanium (Ti), zirconium (Zr), and hafnium (Hf).

6. The thin film processing method according to claim 1, wherein the thin film is a metal nitride thin film with a group 5 metal as the central element.

7. The thin film treatment method according to claim 6, wherein the Group 5 metal is one of vanadium (V), niobium (Nb), and tantalum (Ta).

8. The thin film treatment method according to claim 1, wherein the thin film is a metal film or a metal nitride thin film with a group 6 metal as the central element.

9. The thin film treatment method according to claim 8, wherein the Group 6 metal is one of molybdenum (Mo) and tungsten (W).

10. The surface modifier is O ３ , O ２ , H ２ O, and H ２ O ２ The thin film treatment method according to claim 1, which is any one of them.

11. A method for manufacturing a memory element, comprising the thin-film processing method described in any one of claims 1 to 10.

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