Thin film processing method and method of manufacturing memory device including the same

Abstract

To provide a thin film processing method capable of uniformly removing a thin film.SOLUTION: According to an embodiment of the present invention, a thin film processing method includes supplying a modifier into a chamber in which a substrate is placed to adsorb the modifier onto a thin film formed on the substrate, purging the inside of the chamber, supplying an etching activator into the chamber to process the thin film by reacting with the adsorbed modifier, and purging the inside of the chamber.SELECTED DRAWING: Figure 1

Description

[Technical 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 particularly to a thin film processing method that can enhance etching characteristics using a modifier and an etching activator, and a method for manufacturing a memory device including the same. [Background technology]

[0002] The main mechanism of conventional top-down patterning is to deposit the desired material in the form of a thin film and then fabricate it into the desired size and shape through isotropic wet etching, anisotropic dry etching, reactive ion etching (RIE), etc. However, as the demand for continuous high performance and low power consumption continues to drive smaller and smaller pattern sizes, innovation beyond the current three-dimensional to multidimensional stacked structures is required, and an etching technology with atomic-level precision that surpasses existing wet / dry etching technologies is required.

[0003] This led to the development of an atomic layer etching method inspired by atomic layer deposition. Conventional atomic layer etching methods involve a modification step in which the surface layer is modified using hydrogen fluoride (HF), which has strong reactivity and is therefore easy to modify, and a removal step in which the modified surface layer is removed by reacting with HF.

[0004] However, while hydrogen fluoride used in conventional atomic layer etching has the advantage of strong reactivity, it has problems such as difficulty in adjusting the etching rate according to the input amount or etching only a very thin thickness due to the diffusion of very small fluorine atoms. Furthermore, if fluorine atoms penetrate into unwanted areas, they can cause damage and degrade device characteristics. Similarly, the high temperatures used in the process of removing the modified surface layer can also degrade the characteristics of the underlying film.

[0005] Therefore, to realize ideal ALE (Atomic Layer Etch), which is the opposite concept of ALD (Atomic Layer Deposition), it is necessary to develop materials and processes that can maintain a constant etched thickness and control the etching rate through the termination of surface reactions. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a thin film processing method capable of uniformly removing a thin film and a method for manufacturing a memory device including the same.

[0007] Another object of the present invention is to provide a thin film processing method capable of maintaining thin film characteristics without leaving impurities, and a method for manufacturing a memory device including the same.

[0008] Further objects of the present invention will become more apparent from the following detailed description. [Means for solving the problem]

[0009] According to one embodiment of the present invention, a thin film processing method includes a modifier supply step of supplying a modifier into a chamber in which a substrate is placed and causing the modifier to adsorb to a thin film formed on the substrate, a step of purging the inside of the chamber, a thin film processing step of supplying an etching activator into the chamber and reacting with the adsorbed modifier to process the thin film, and a step of purging the inside of the chamber.

[0010] The modifier can be represented by the following <Chemical Formula 1>. [ka] In the <Chemical Formula 1>, n is independently selected from integers of 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; 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.

[0011] The modifier can be represented by the following <Chemical Formula 2>. [ka] In the <Chemical Formula 2>, R1 is selected from linear, branched, and cyclic alkyl groups having 1 to 5 carbon atoms, and linear, branched, and cyclic chloroalkyl groups having 1 to 5 carbon atoms; R2 is selected from hydrogen and linear, branched, and cyclic alkyl groups having 1 to 5 carbon atoms.

[0012] The modifier can be represented by the following <Chemical Formula 3>. [ka] In the <Chemical Formula 3>, n is an integer selected from 1 to 5, R1 and R2 are selected from hydrogen or chlorine elements, R3 and R4 are selected from hydrogen or linear, branched, and cyclic alkyl groups having 1 to 5 carbon atoms.

[0013] The modifier can be represented by the following <Chemical Formula 4>. [ka] In the <Chemical Formula 4>, n is an integer selected from 1 to 5, R1 and R2 are selected from hydrogen or chlorine elements; R3 and R4 are selected from hydrogen or linear, branched, and cyclic alkyl groups having 1 to 5 carbon atoms.

[0014] The etching activator may be any one of O3, O2, and H2O.

[0015] The thin film may have one of Al, Ti, Hf, Nb, Ta, Mo, and W as its central element.

[0016] The thin film may be any one of a metal film, a metal oxide, a metal nitride, and a metal sulfide. In this case, the metal film may include a binary or ternary compound doped with one or more other elements to improve its characteristics.

[0017] The thin film treatment method can be carried out at a temperature of 50 to 700°C.

[0018] According to one embodiment of the present invention, a method for manufacturing a volatile memory device may include the thin film processing method described above.

[0019] According to one embodiment of the present invention, a method for manufacturing a nonvolatile memory device may include the thin film processing method described above. [Effects of the Invention]

[0020] According to one embodiment of the present invention, the thin film can be removed uniformly.

[0021] Furthermore, since the etching activator is uniformly adsorbed on the surface of the material to be etched in atomic layers, the degree of etching can be adjusted more accurately than in conventional etching methods. [Brief explanation of the drawings]

[0022] [Figure 1] 4 is a graph that schematically illustrates a supply cycle according to an embodiment of the present invention. [Figure 2] 1 is a graph showing a comparison of thin film thickness per cycle depending on whether an etching activator is used or not in Example 1 of the present invention. [Figure 3] 10 is a graph showing etching thickness per cycle according to the use of an etching activator in Example 5 of the present invention. [Figure 4]10 is a graph showing etching thickness per cycle according to the use of an etching activator in Example 6 of the present invention. [Figure 5] 1 is a graph showing the thickness of a Mo thin film depending on the supply time of a modifier in Example 7 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying FIGS.

[0024] The embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. These embodiments are provided to explain the present invention in more detail to those skilled in the art to which the invention pertains. Therefore, the shape of each element shown in the drawings may be exaggerated to emphasize a clearer description.

[0025] 1 is a graph showing a schematic diagram of a supply cycle according to an embodiment of the present invention. A substrate is loaded into a process chamber, and the following process conditions are adjusted. The process conditions may include substrate or process chamber temperature, chamber pressure, and gas flow rates, and the temperature is between 50 and 700°C.

[0026] The substrate is exposed to the modifier supplied into the chamber, and the modifier is adsorbed into a thin film formed on the surface of the substrate. The thin film may have one of Al, Ti, Hf, Nb, Ta, Mo, or W as its central element, and may be one of a metal film, metal oxide, metal nitride, or metal sulfide. In this case, the metal film may include a binary or ternary compound doped with one or more other elements to improve its characteristics. The modifier supply step is carried out at a temperature of 50 to 700°C.

[0027] Specifically, the modifier can be represented by the following <Chemical Formula 1>. [ka] In the <Chemical Formula 1>, n is independently selected from integers of 0 to 5; X1 to X3 are each independently selected from an alkoxy group having 1 to 5 carbon atoms and a dialkylamino group having 1 to 5 carbon atoms; 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.

[0028] Specifically, in the <Chemical Formula 1>, when n=0, X1 to X3 are methoxy groups (-OCH3), and R is a hydrogen atom, the modifier may be trimethyl orthoformate.

[0029] In addition, in the <Chemical Formula 1>, when n=0, X1 to X3 are ethoxy groups (-OC2H5), and R is a hydrogen atom, the modifier may be triethyl orthoformate.

[0030] In addition, in the above <Chemical Formula 1>, when n=0, X1 to X2 are methoxy groups (-OCH3), X3 is a dimethylamine group (-N(CH3)2), and R is a hydrogen atom, the modifier may be dimethylformamide dimethyl acetal.

[0031] In addition, in the above <Chemical Formula 1>, when n=0, X1 to X3 are dimethylamine groups (-N(CH3)2), and R is a hydrogen atom, the modifier may be tris(dimethylamino)methane.

[0032] The modifier can be represented by the following <Chemical Formula 2>. [ka] In the <Chemical Formula 2>, R1 is selected from linear, branched, and cyclic alkyl groups having 1 to 5 carbon atoms, and linear, branched, and cyclic chloroalkyl groups having 1 to 5 carbon atoms; R2 is selected from hydrogen and linear, branched, and cyclic alkyl groups having 1 to 5 carbon atoms.

[0033] Specifically, in the <Chemical Formula 2>, when R1 is a chloromethyl group (-CH2Cl) and R2 is a hydrogen atom, the modifier may be chloroacetic acid.

[0034] In the above <Chemical Formula 2>, when R1 is a dichloromethyl group (-CHCl2) and R2 is a methyl group, the modifier may be methyl dichloroacetate.

[0035] The modifier can be represented by the following <Chemical Formula 3>. [ka] In the <Chemical Formula 3>, n is an integer selected from 1 to 5, R1 and R2 are selected from hydrogen or chlorine elements; R3 and R4 are selected from hydrogen or linear, branched, and cyclic alkyl groups having 1 to 5 carbon atoms.

[0036] The modifier can be represented by the following <Chemical Formula 4>. [ka] In the <Chemical Formula 4>, n is an integer selected from 1 to 5, R1 and R2 are selected from hydrogen or chlorine elements; R3 and R4 are selected from hydrogen or linear, branched, and cyclic alkyl groups having 1 to 5 carbon atoms.

[0037] Specifically, in the <Chemical Formula 4>, when n=1, R1 is hydrogen, R2 is chlorine, and R3 to R4 are methyl groups, the modifier may be 3-chloro-2,4-pentanedione.

[0038] However, the modifier is not limited to the above examples.

[0039] Thereafter, a purge gas (eg, an inert gas such as Ar) is supplied into the chamber to remove or purify any unadsorbed modifier or by-products.

[0040] The substrate is then exposed to an etching activator supplied into the chamber, which reacts with the modifier to etch the thin film. The etching activator supply step is carried out at a temperature of 50 to 700°C.

[0041] Specifically, the etching activator may be any one of O3, O2, and H2O, but the etching activator is not limited to the above examples.

[0042] Thereafter, a purge gas (for example, an inert gas such as Ar) is supplied into the chamber to remove or purify any unadsorbed etching activator or by-products.

[0043] Example 1: Trimethyl orthoform + O Nb2O5 thin films were etched at 300℃ using trimethyl orthoformate (TMOF) as a modifier and O3 as an etching activator.

[0044] The etching process according to the supply cycle shown in FIG. 1 was as follows, and the following process was performed as one cycle. 1) A modifier is supplied into the chamber and absorbed onto the substrate. 2) Ar gas is supplied into the chamber to remove any unadsorbed modifier or by-products. 3) An etching activator is supplied into the chamber to react with the modifier and etch the thin film.

[0045] 2 is a graph comparing the thin film thickness per cycle with and without the use of an etching activator in Example 1 of the present invention. When only trimethyl orthoform (TMOF) was used as a modifier, almost no etching occurred in any of the thin films.

[0046] On the other hand, when an etching activator (TMOF+O3) was used, the thickness of the thin film decreased linearly. It was confirmed that the surface reaction of the two materials could uniformly etch the thin film at the atomic layer level.

[0047] The modifier according to Example 1 of the present invention forms a modified monolayer through a substitution reaction with the metal element on the top surface, or exists on the surface through physical adsorption. Because the modifier has a highly electronegative oxygen atom and a highly reactive central carbon, it can easily dissociate when an etching activator is added, providing an alkoxy group on the surface, which can then be removed by forming a volatile by-product represented by M(OR)x.

[0048] The following Table 1 is a graph showing the etching rates of the thin films confirmed in Example 1.

[0049] [Table 1]

[0050] Examples 2-4: Trimethyl orthoform + O Using trimethyl orthoformate as a modifier and O3 as an etching activator, TiO2, Mo, and MoN thin films were etched at 380℃.

[0051] The etching process was carried out in the same manner as in Example 1, following the supply cycle shown in FIG.

[0052] The following Table 2 is a graph showing the etching rates of the thin films confirmed in Examples 2 to 4.

[0053] [Table 2]

[0054] As in Example 1, it was confirmed that the surface reaction of two substances can uniformly etch a thin film in atomic layer units.

[0055] Example 5: Triethyl orthoform + O Nb2O5 and TiO2 thin films were etched at 340℃ using triethyl orthoformate (TEOF) as a modifier and O3 as an etching activator.

[0056] The etching process according to the supply cycle shown in FIG. 1 was as follows, and the following process was performed as one cycle. 1) A modifier is supplied into the chamber and absorbed onto the substrate. 2) Ar gas is supplied into the chamber to remove any unadsorbed modifier or by-products. 3) An etching activator is supplied into the chamber to react with the modifier and etch the thin film.

[0057] Figure 3 is a graph showing the etching thickness per cycle depending on the use of an etching activator in Example 5 of the present invention. It was confirmed that the film thickness decreased linearly when triethyl orthoform (TEOF) as a modifier and O3 as an etching activator were used. It was confirmed that the surface reaction of the two materials allowed for uniform etching of the thin film at the atomic layer level.

[0058] Example 6: Dimethylformamide dimethyl acetal + O3 Nb2O5 and TiO2 thin films were etched at 340℃ using dimethylformamide dimethyl acetal (DFDA) as a modifier and O3 as an etching activator.

[0059] The etching process according to the supply cycle shown in FIG. 1 was as follows, and the following process was performed as one cycle. 1) A modifier is supplied into the chamber and absorbed onto the substrate. 2) Ar gas is supplied into the chamber to remove any unadsorbed modifier or by-products. 3) An etching activator is supplied into the chamber to react with the modifier and etch the thin film.

[0060] Figure 4 is a graph showing the etching thickness per cycle depending on the use of an etching activator in Example 6 of the present invention. When dimethylformamide dimethyl acetal (DFDA) as a modifier and O3 as an etching activator were used, the film thickness decreased linearly, the etching rate was relatively high, and the film was completely etched after 50 cycles. It was confirmed that the surface reaction of the two materials allows for uniform etching of the thin film at the atomic layer level.

[0061] Example 7: Dimethylformamide dimethyl acetal + O3 Using dimethylformamide dimethyl acetal (DFDA) as a modifier and O3 as an etching activator, the Mo thin film was etched at 150℃.

[0062] The etching process according to the supply cycle shown in FIG. 1 was as follows, and the following process was performed as one cycle. 1) A modifier is supplied into the chamber and absorbed onto the substrate. 2) Ar gas is supplied into the chamber to remove any unadsorbed modifier or by-products. 3) An etching activator is supplied into the chamber to react with the modifier and etch the thin film.

[0063] Figure 5 is a graph showing the thickness of a Mo thin film as a function of modifier supply time in Example 7 of the present invention. When dimethylformamide dimethyl acetal (DFDA) was used as a modifier and O3 was used as an etching activator, it was confirmed that etching did not occur continuously even when the modifier supply time was extended, but rather reached saturation. It was confirmed that a thin film could be uniformly etched at an atomic layer level with an etching rate of 3.9 Å / cycle.

Claims

1. In the thin film processing method, 1. A thin film processing method, comprising: a modifying agent supplying step of supplying a modifying agent into a chamber in which a substrate is placed, and adsorbing the modifying agent into a thin film formed on the substrate; a purging step of supplying an etching activator into the chamber, and treating the thin film by reacting with the adsorbed modifying agent; and a purging step of the chamber.

2. 2. The thin film processing method according to claim 1, wherein the modifier is represented by the following formula 1: In the <Chemical Formula 1>, n is independently selected from integers of 0 to 5; X 1 ~X 3 are each independently selected from an alkoxy group having 1 to 5 carbon atoms and a dialkylamino group having 1 to 5 carbon atoms; R is selected from the group consisting of 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.

3. 2. The thin film processing method according to claim 1, wherein the modifying agent is represented by the following formula 2: In the <Chemical Formula 2>, R 1 is selected from a linear, branched or cyclic alkyl group having 1 to 5 carbon atoms, and a linear, branched or cyclic chloroalkyl group having 1 to 5 carbon atoms; R 2 is selected from hydrogen, straight-chain, branched, and cyclic alkyl groups having 1 to 5 carbon atoms.

4. 2. The thin film processing method according to claim 1, wherein the modifying agent is represented by the following formula 3: In the <Chemical Formula 3>, n is selected from the group consisting of integers from 1 to 5; R 1 , R 2 is selected from hydrogen or chlorine elements, R 3 , R 4 is selected from hydrogen or a linear, branched or cyclic alkyl group having 1 to 5 carbon atoms.

5. 2. The thin film processing method according to claim 1, wherein the modifying agent is represented by the following formula 4: In the <Chemical Formula 4>, n is selected from the group consisting of integers from 1 to 5; R 1 , R 2 is selected from hydrogen or chlorine elements, R 3 , R 4 is selected from hydrogen or a linear, branched or cyclic alkyl group having 1 to 5 carbon atoms.

6. The etching activator is O 3 , O 2 , H 2 2. The thin film processing method according to claim 1, wherein the method is one of the above.

7. 2. The thin film processing method according to claim 1, wherein the thin film has one of Al, Ti, Hf, Nb, Ta, Mo, and W as a central element.

8. 2. The thin film processing method according to claim 1, wherein the thin film is one of a metal film, a metal oxide film, a metal nitride film, and a metal sulfide film.

9. 2. The thin film processing method according to claim 1, wherein the thin film processing method proceeds at a temperature of 50 to 700.degree.

10. A method for manufacturing a volatile memory element, comprising any one of the thin film processing methods according to claims 1 to 9.

11. A method for manufacturing a nonvolatile memory element, comprising any one of the thin film processing methods according to claims 1 to 9.

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