WO2025143683A1 - Electron beam-ion assisted deposition of yttrium aluminate thin film - Google Patents

Abstract

The invention relates to electron beam-ion assisted deposition of a yttrium aluminate compound. The present invention provides a method for electron beam-ion assisted deposition, by which a Y-Al-O compound thin film is deposited on a substrate arranged in an electron beam ion-assisted deposition apparatus, the method comprising the steps of: loading an aluminum source into a first holder and loading a yttrium source into a second holder of an electron beam evaporator of the deposition apparatus; on the substrate, forming a seed layer by ion-beam assisted deposition of the aluminum source evaporated from the first holder of the electron beam evaporator; and forming a Y-Al-O layer on the seed layer by beam-ion assisted deposition while evaporating the yttrium source and the aluminum source from the first holder and the second holder of the electron beam evaporator simultaneously.

Description

Electron beam ion assisted deposition of yttrium aluminate thin films

The present invention relates to a method for manufacturing an yttrium aluminate thin film by electron beam-ion assisted deposition (EB-IAD).

In general, PVD coating using electron beam equipment is a deposition method that melts and vaporizes raw materials and deposits them on a substrate. It is a type of physical coating method that utilizes the phase change (solid → liquid → vapor → solid) of the material during the process. Electron Beam Ion Assisted Deposition (EB-IAD) is a deposition method that combines electron beam evaporation and ion beam deposition technology.

In the case of _PVD coating of binary _{compounds such as Al2O3 or Y2O3 , even} if the target material undergoes a phase change from solid → liquid → gas → solid and is deposited on the substrate, the coating film exhibits a composition similar to that of the target material.

However, in the case of compounds with three or more components, such as YAG (Y ₃ Al ₅ O ₁₂ ) and YAM (Y ₄ Al ₂ O ₉ ), there is a problem that the compound composition changes in a direction in which the phase change is likely to occur during the phase change from solid to liquid → vapor → solid, especially during the vapor → solid phase process during deposition on the substrate. For example, in PVD using a YAG target composition, a coating film in which a binary compound such as Al ₂ O ₃ or Y ₂ O ₃ is dominant can be obtained.

Meanwhile, other problems also arise in the PVD deposition method of compounds consisting of three or more components. For example, there is a problem in that it is difficult to obtain a crystalline coating film using the EB-IAD coating method.

In the case of such amorphous coating films, crystallization treatment may be possible through heat treatment, but in the process of changing from an amorphous to a crystalline thin film, the bonding strength with the base material decreases, resulting in a thin film with an unstable bonding state.

Therefore, there is a need for an EB-IAD coating process that minimizes problems occurring in conventional PVD methods while achieving a film composition close to the target.

In order to solve the problems of the above prior art, the present invention aims to provide an electron beam ion-assisted deposition method for forming a multicomponent Y-Al-O compound coating.

In addition, the present invention aims to provide an electron beam ion assisted deposition method for forming a Y-Al-O compound coating having a high crystallinity.

In addition, the present invention aims to provide an electron beam ion assisted deposition method for forming a Y-Al-O compound coating having high bonding strength with a base material.

In order to achieve the above technical problem, the present invention provides a method for electron beam ion assisted deposition of a Y-Al-O compound thin film on a substrate placed in an electron beam ion assisted deposition apparatus, the method comprising the steps of: loading an aluminum source into a first holder of an electron beam evaporator of the deposition apparatus and loading an yttrium source into a second holder; performing ion beam assisted deposition on the substrate using the aluminum source evaporated in the first holder of the electron beam evaporator to form a seed layer; and performing ion assisted deposition while simultaneously evaporating the yttrium source and the aluminum source in the first holder and the second holder of the electron beam evaporator to form a Y-Al-O layer on the seed layer.

In the present invention, the Y-Al-O compound may include at least one selected from the group consisting of YAG, YAM, and YAP.

In the present invention, the yttrium source may include Y ₂ O ₃ , and the aluminum source may include Al ₂ O ₃ .

In the present invention, the Y-Al-O layer forming step may include a step of heat treating the Y-Al-O layer. At this time, the Y-Al-O layer heat treatment step is preferably performed at 900 to 1200°C.

In order to achieve the above other technical tasks, the present invention provides an electron beam ion assisted coating including an Al ₂ O ₃ seed layer on a substrate; and a crystalline Y-Al-O layer on the seed layer. In the present invention, the Y-Al-O layer may include YAG. In addition, the Y-Al-O layer may include YAM.

According to the present invention, it is possible to provide an electron beam ion assisted deposition method suitable for forming a coating of a ternary or more compound such as a Y-Al-O compound.

In addition, according to the present invention, it is possible to provide an electron beam ion assisted deposition method suitable for forming a Y-Al-O compound coating having a high crystallinity.

In addition, according to the present invention, it is possible to form a Y-Al-O compound coating having a high bonding strength with a base material.

FIG. 1 is a schematic diagram illustrating an electron beam ion assisted deposition device according to one embodiment of the present invention.

FIG. 2 is a drawing schematically illustrating an electron beam ion assisted deposition method according to one embodiment of the present invention.

Figure 3 shows the XPS analysis results and electron microscope images of a thin film specimen manufactured according to Experimental Example 1 of the present invention.

Figure 4 is a graph showing the XPS analysis results before and after heat treatment of a thin film specimen manufactured according to Experimental Example 2 of the present invention.

Figure 5 is an electron microscope photograph of a cross-section of a thin film specimen manufactured according to Experimental Example 2 of the present invention.

Figure 6 is a graph showing the results of XRD analysis of a thin film specimen manufactured according to Experimental Example 2 of the present invention.

Figure 7 is a graph showing the XPS analysis results of the thin film specimen produced in Comparative Example 1.

Figure 8 is a graph showing the results of XRD analysis before and after heat treatment of a thin film specimen deposited in Comparative Example 1.

Figure 9 is a photograph of the surface and cross-section of the specimen deposited in Comparative Example 1 after heat treatment.

Figure 10 is a graph showing the results of EDS analysis before and after heat treatment of a thin film specimen manufactured according to Example 1 of the present invention.

Figure 11 is a graph showing the results of XRD analysis before and after heat treatment of a thin film specimen deposited in Example 1 of the present invention.

Figure 12 is a photograph of the surface and cross-section of a specimen deposited in Example 1 of the present invention after heat treatment.

Figure 13 is a graph showing the results of measuring the hardness and bonding strength of the thin film specimens of Comparative Example 1 and Example 1.

Figure 14 is a photograph of the surface of a thin film specimen manufactured according to Example 1 of the present invention taken at each heat treatment temperature section.

Figure 15 is a graph showing the results of hardness measurement according to heat treatment temperature range of a thin film specimen manufactured according to Example 1 of the present invention.

Figure 16 is a graph showing the results of measuring the crystal size according to the heat treatment temperature range of a thin film specimen manufactured according to Example 1 of the present invention.

Figure 17 is a graph showing the results of XRD analysis by heat treatment temperature range of a thin film specimen manufactured according to Example 1 of the present invention.

Figures 18 (a) and (b) are graphs showing the results of EDS analysis before and after heat treatment of the thin film specimen produced in Comparative Example 2, respectively.

Figures 19 (a) and (b) are graphs showing the results of XRD analysis before and after heat treatment of a thin film specimen deposited in Comparative Example 2.

Figure 20 is a photograph of the surface of a specimen deposited in Comparative Example 2 before and after heat treatment.

Figures 21 (a) and (b) are graphs showing the results of EDS analysis before and after heat treatment of the thin film specimen manufactured in Example 2, respectively.

Figures 22 (a) and (b) are graphs showing the results of XRD analysis of the thin film specimen deposited in Example 2 before and after heat treatment.

Figure 23 is a photograph of the surface of a specimen deposited in Example 2 before and after heat treatment.

Figure 24 (a) is a graph showing the results of hardness measurements before and after heat treatment of thin film specimens of Comparative Example 2 (denoted as YAM) and Example 2 (denoted as Hybrid-YAM), and (b) is a graph showing the results of bonding strength measurements before and after heat treatment of thin film specimens of Comparative Example 2 and Example 2.

Figure 25 is a photograph of the surface of a thin film specimen manufactured according to Example 2 of the present invention taken at each heat treatment temperature section.

Figure 26 is a graph showing the results of hardness measurement according to heat treatment temperature range of a thin film specimen manufactured according to Example 2 of the present invention.

Figure 27 is a graph showing the results of measuring the crystal size according to the heat treatment temperature range of a thin film specimen manufactured according to Example 2 of the present invention.

Figure 28 is a graph showing the results of XRD analysis by heat treatment temperature range of a thin film specimen manufactured according to Example 2 of the present invention.

Figure 29 is a photograph of the surface of a thin film specimen manufactured according to Comparative Example 3 before and after heat treatment.

Figure 30 is a graph showing the crystal size after heat treatment of Example 3 and Comparative Example 3.

Figure 31 is a graph showing the results of hardness measurements after heat treatment in Example 3 and Comparative Example 3.

Figure 32 is a graph showing the results of bonding strength measurements after heat treatment in Example 3 and Comparative Example 3.

Figure 33 is a graph showing the results of XRD analysis after heat treatment of Example 3 and Comparative Example 3.

Figure 34 is a photograph of the surface of a thin film specimen manufactured according to Comparative Example 4 before and after heat treatment.

Figure 35 is a graph showing the crystal size after heat treatment of Example 4 and Comparative Example 4.

Figure 36 is a graph showing the results of hardness measurements after heat treatment in Example 4 and Comparative Example 4.

Figure 37 is a graph showing the results of bonding strength measurements after heat treatment in Example 4 and Comparative Example 4.

Figure 38 is a graph showing the results of XRD analysis after heat treatment of Example 4 and Comparative Example 4.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

Whenever it is said throughout this specification that a part "includes" a component, this does not exclude other components, but rather includes other components, unless otherwise stated.

FIG. 1 is a schematic diagram illustrating an electron beam ion assisted deposition device according to one embodiment of the present invention.

An electron beam ion assisted deposition device (100) comprises a vacuum chamber (10), a deposition substrate (20), a deposition source holder (32, 34) provided on the lower side of the deposition substrate (20) and storing a deposition source, an electron beam evaporator (30) for emitting deposition particles by an electron beam generated from an electron beam source (not shown), and an ion beam source (40) for emitting an ion beam to transfer energy to the deposition particles. In addition, the device may include a substrate heater (50) for heating the substrate.

As described above, the electron beam evaporator (30) in the present invention has a plurality of source holders (32, 34). A shutter (36) may be provided on the source holders (32, 24) as a selection means for selectively evaporating a specific source from the plurality of source holders.

The above vacuum chamber (10) can be maintained at a vacuum level of about 0.0001 torr by a vacuum pump (not shown). In addition, the ion beam source (40) mainly receives argon (Ar) gas to generate an ion beam having high energy. The ion beam source (40) can receive, for example, argon (Ar) gas to generate an ion beam having high energy. The deposition particles emitted from the deposition material in the source holder by the electron beam can be deposited on the substrate (20). At this time, the adhesion between the substrate and the deposition film can be improved by emitting an ion beam having high energy from the ion beam source (40) and transmitting it to the deposition particles.

In the present invention, different sources are stored in the plurality of source holders (32 34) of the electron beam evaporator (30). For example, an aluminum source such as alumina may be stored in the first source holder (32), and an yttrium source such as yttria may be stored in the second source holder (34).

Below, an electron beam ion assisted deposition method using the aforementioned multiple source holders is described.

FIG. 2 is a drawing schematically illustrating an electron beam ion assisted deposition method according to one embodiment of the present invention.

First, as shown in (a) of Fig. 2, a substrate is placed in a chamber, and then an aluminum source of the first holder is evaporated by an electron beam while an ion beam is used as an auxiliary deposition tool to form a seed layer. In the present invention, the seed layer may preferably include an aluminum compound such as Al ₂ O ₃ , but is not limited thereto.

Next, on the substrate on which the seed layer is formed, as illustrated in FIG. 2 (b), the aluminum source of the first holder and the yttrium source of the second holder are simultaneously electron beam evaporated while the ion beam is used as an auxiliary deposition tool to co-deposit the aluminum source and the yttrium source, thereby depositing the yttrium aluminate compound. According to one embodiment of the present invention, for example, the yttrium aluminate may include at least one compound selected from the group consisting of YAG, YAM, and YAP.

The present invention is described in detail below by describing embodiments of the present invention.

<Experimental Example 1>

YAG powder was loaded into the source holder of the electron beam evaporator. For deposition, the inside of the device was placed under a high vacuum of 9.0 x 10 ^-5 to 1.0 x 10 ^-7 Torr, and the substrate surface was cleaned using an ion beam. Al ₂ O ₃ substrate was used as the substrate.

A Y-Al-O thin film was deposited by evaporating YAG powder in a source hold with an electron beam and irradiating it with an ion beam of a mixed gas of Ar and O ₂ . The process conditions were as follows.

- Vacuum 1.0~3.0 x 4 Torr

- Process temperature 100~200℃

- YAG powder evaporation rate 2.0~4.0Å/s

- Ar flow rate: 10~40 sccm

- O2 flow rate: 10~40 sccm

Fig. 3 (a) is a graph showing the XPS analysis results of the thin film specimen manufactured in Experimental Example 1, and Fig. 3 (b) is an electron microscope photograph observing the cross-section of the manufactured thin film specimen.

Referring to Fig. 3 (a), it can be confirmed that the Al and Y contents are not constant depending on the etching depth of the thin film. It can be seen that the coated thin films have a content deviation depending on the depth within the thin film because Al ₂ O ₃ and Y ₂ O ₃ in the source have different evaporation amounts and evaporation rates. Accordingly, it can be seen that it is impossible to produce a Y-Al-O thin film having a desired composition ratio, such as YAG.

Meanwhile, as shown in (b) of Fig. 3, the cross-sectional observation results of the thin film show that there is a compositional deviation in each layer, indicating that the film has a layered structure.

<Experimental Example 2>

Two source holders were used in an electron beam evaporator, one source holder was loaded with _{Y2O3 powder} , and the other source holder was loaded with _{Al2O3 powder} . By alternately opening and closing _{the Al2O3} source holder and _Y2O3 with a shutter _{, a total of 60 stacked thin films consisting of Al2O3 /Y2O3 / Al2O3 / Y2O3 were} deposited _. The thickness of each layer of the deposited thin _films was maintained _in the range of 16–37 nm. _{An Al2O3} substrate was used as the substrate. The remaining conditions were the same as in Experimental Example 1. The manufactured thin film specimens were heat-treated at a temperature of 300–500°C to crystallize the thin film in the deposited state.

Figure 4 is a graph showing the XPS analysis results before and after heat treatment of the thin film specimen obtained in Experimental Example 2.

Fig. 4 (a) shows the XPS analysis results of the thin film specimen before heat treatment, and (b) to (d) are graphs showing the XPS analysis results of the thin film specimen after heat treatment at temperatures of 300°C, 400°C, and 500°C for 1 to 2 hours, respectively.

Referring to each graph in Fig. 4, it can be seen that the thin film specimen before heat treatment has a laminated structure composed of thin films with different compositions for each layer. In addition, it can be seen that the compositional deviation of each layer is reduced by diffusion after heat treatment, but an imbalance in the composition still occurs between each layer.

Figure 5 is an electron microscope photograph of a cross-section of a thin film specimen obtained after heat treatment at 500°C for 1 to 2 hours in Experimental Example 2.

Referring to Fig. 5, it can be seen that interlayer cracks occur due to heat treatment, and from this it can be seen that in the case of laminated deposition, crystallization through a high-temperature heat treatment process becomes difficult.

Figure 6 is a graph showing the results of XRD analysis of a thin film specimen obtained after heat treatment at 500°C for 1 to 2 hours in Experimental Example 2.

Referring to Fig. 6, some amorphous structures exist within the specimen, and Al ₂ O ₃ and Y ₂ O ₃ peaks are confirmed to be the main peaks. From this, it can be seen that it is difficult to manufacture a thin film having a phase of a Y-Al-O compound such as YAG by layered deposition.

<Example 1>

Two source holders were used in the electron beam evaporator, with Y ₂ O ₃ powder loaded into one source holder and Al ₂ O ₃ powder loaded into the other source holder.

First, only the Al ₂ O ₃ source holder was opened, and then an Al ₂ O ₃ seed layer was generated on the Al ₂ O ₃ substrate. The thickness of the generated seed layer can be controlled within the range of 10 to 500 nm, and for example, the thickness of the seed layer can be 100 to 500 nm.

Subsequently, the Al ₂ O ₃ source holder and the Y ₂ O ₃ source holder were simultaneously opened to form a Y-Al-O thin film on the seed layer. At this time, the evaporation rate of each source holder was changed so that the ratio of Y and Al in the thin film was 1:2 to 1:3. The total thickness of the manufactured thin film was 5 μm.

In addition, the deposition conditions of the seed layer and thin film were the same as in Experimental Example 1, and the manufactured thin film specimens were heat-treated at a temperature of 900 to 1200°C for 1 to 3 hours. Since rapid temperature changes may cause peeling of the substrate and the coating layer, the heating rate was maintained in the range of 2 to 5°C/min.

<Comparative Example 1>

A Y-Al-O thin film was formed using the same method as in Example 1, but the seed layer formation process was omitted.

The deposition conditions applied to each source during deposition of the seed layer and thin film of Example 1 and Comparative Example 1 are summarized in Table 1 below.

Category A Coating Source Evaporation rate
(Å/s) Deposition thickness
(㎛) Deposition material ratio
(%) Comparative Example 1 _Y2O3 ( _thin film) 1.0~2.0 1.0~2.0 20~40 Al ₂ O ₃ (thin film) 2.0~3.0 3.0~4.0 60~80 Example 1 Al ₂ O ₃ (seed) 1.0~2.0 0.5~1.0 5~10 _Y2O3 ( _thin film) 1.0~2.0 1.0~2.0 10~40 Al ₂ O ₃ (thin film) 2.0~3.0 3.0~4.0 50~65

The meaning of each deposition condition is as follows.

Evaporation rate: The rate at which the source evaporates from the source holder per second.

Deposition thickness: Deposition thickness of each source based on a final coating thickness of 5㎛

Deposit Material Ratio: The percentage of each source material included in the final coating based on the total deposition thickness.

XPS analysis and XRD analysis were performed on the specimens manufactured in Example 1 and Comparative Example 1.

Figures 7 (a) and (b) are graphs showing the XPS analysis results before and after heat treatment of the thin film specimen produced in Comparative Example 1, respectively.

Referring to Fig. 7, it can be seen that the contents of Y, Al, and O are generally maintained uniformly from the surface to the interior. From the XPS analysis results, the atomic fractions of Al, Y, and O in the thin film were calculated to be approximately 28 at%, 12 at%, and 58 at%, respectively, and it was confirmed that there was almost no change in the contents before and after heat treatment.

Figures 8 (a) and (b) are graphs showing the results of XRD analysis before and after heat treatment of a thin film specimen deposited in Comparative Example 1.

Referring to Figure 8, it can be seen that the thin film, which existed mainly in an amorphous state before heat treatment, undergoes crystallization through heat treatment. In the XRD pattern, the main peak of the YAG crystal is the (420) peak around 2θ=33~34°, and in addition, the _{Al2O3 phase} can be confirmed.

Figure 9 is a photograph of the surface and cross-section of the specimen deposited in Comparative Example 1 after heat treatment.

Referring to Figure 9, the specimen of Comparative Example 1 shows numerous crater structures on the surface, pores formed by the boiling phenomenon due to a decrease in bonding strength were confirmed, and it can be seen that cracks that penetrate the entire thin film occurred.

Figures 10 (a) and (b) are graphs showing the results of EDS analysis before and after heat treatment of the thin film specimen produced in Example 1, respectively.

From the electron microscope image of Fig. 10, it can be seen that a seed layer is formed between the substrate and the thin film, and from the EDS analysis results, it can be confirmed that each element is uniformly distributed throughout the entire thickness of the thin film.

Figures 11 (a) and (b) are graphs showing the results of XRD analysis of the thin film specimen deposited in Example 1 before and after heat treatment.

Referring to Fig. 11, it can be seen that the thin film specimen manufactured in Example 1 existed in an amorphous phase before heat treatment, and was substantially converted into a YAG single crystal phase through heat treatment.

Figure 12 is a photograph of the surface and cross-section of the specimen deposited in Example 1 after heat treatment.

Referring to Fig. 12, it can be seen that the specimen of Example 1 has a stable surface structure and also has a very stable bonding state with the substrate.

Figure 13 is a graph showing the results of measuring the hardness and bonding strength of the thin film specimens of Comparative Example 1 and Example 1. For each measurement, specimens after heat treatment were used.

Hardness was calculated as a result of measuring the indentation with a load of 50.00 mN using a nanoindenter device from Anton Paar, and bonding strength was calculated as a result of measuring the scratch up to 5 mm with a load of 1 to 30 N using a scratch tester from Anton Paar.

Referring to Figure 13, it can be seen that the thin film specimen of Example 1 (Hybrid) exhibits higher hardness and bonding strength than that of Comparative Example 1 (N-Hybrid).

Below, the experimental results of heat treatment at different temperatures for Example 1 are described in detail.

Figure 14 is a photograph of the surface of a thin film specimen manufactured according to Example 1 of the present invention taken at each heat treatment temperature section.

The total thickness of the manufactured thin film (including the seed layer) is 5.0 μm, and the photographs were taken at a magnification of 100 times using an optical microscope. Fig. 14a is a specimen that was not heat-treated (0°C), and Figs. 14b, 14c, 14d, 14e, and 14f are photographs of specimens that were heat-treated at heat treatment temperatures of 200°C, 900°C, 1,000°C, 1,100°C, and 1,200°C for 1 to 2 hours, respectively.

In the specimens heat-treated at 200℃~1,100℃, no craters were formed on the specimen surface and no peeling occurred in the thin film. Therefore, it can be seen that the thin film is well bonded to the substrate and is stably maintained during the heat treatment. On the other hand, at 1,200℃, craters were formed on the surface of the thin film, indicating that the surface condition was deteriorated due to the heat treatment.

Figure 15 is a graph showing the results of measuring hardness according to heat treatment temperature range of a thin film specimen manufactured according to Example 1 of the present invention.

The hardness is 8.51 GPa when not heat treated (0℃) and 8.72 GPa at 200℃, and the hardness is similar up to 200℃. The hardness slightly increased to 11.52 GPa at 900℃, which is expected to be because the thin film exists in an amorphous form after heat treatment and _the phase bonding between _Al2O3 and _Y2O3 did not occur. It significantly increased to 18.10 GPa, 18.89 GPa, and _19.21 GPa at 1,000℃, 1,100℃, and 1,200℃, respectively.

Figure 16 is a graph showing the results of measuring the crystallite size according to the heat treatment temperature range of a thin film specimen manufactured according to Example 1 of the present invention.

The crystal sizes were measured as 1.10 nm, 1.12 nm, and 1.04 nm at 0℃, 200℃, and 900℃, respectively, but significantly increased to 18.90 nm, 19.70 nm, and 24.10 nm at 1,000℃, 1,100℃, and 1,200℃, respectively. Therefore, it can be seen that crystallization occurred at 1,000℃, 1,100℃, and 1,200℃.

Figure 17 is a graph showing the results of XRD analysis by heat treatment temperature range of a thin film specimen manufactured according to Example 1 of the present invention.

XRD analysis results show that the thin film exists in an amorphous phase at 0℃, 200℃, and 900℃, _and crystallization progresses into a YAG crystal phase at 1,000℃, 1,100℃, and 1,200℃. At 1,200℃, it is confirmed that YAG and _Al2O3 are mixed, and it can be seen that craters are formed on the surface of the thin film and phase bonding occurs at 1,200℃.

As explained above, in the case of YAG, it can be seen that the crystallization reaction occurs at a heat treatment temperature of more than 900℃ and less than 1,200℃, preferably more than 1,000℃ and less than 1,100℃, and the properties of the thin film are improved.

<Example 2>

YAM was deposited in the same manner as in Example 1. First, only the Al ₂ O ₃ source holder was opened, and then an Al ₂ O ₃ seed layer was created on the Al ₂ O ₃ substrate. The thickness of the seed layer was 400 to 500 nm.

Subsequently, the Al ₂ O ₃ source holder and the Y ₂ O ₃ source holder were simultaneously opened to form a Y-Al-O thin film on the seed layer. At this time, the evaporation rate of each source holder was changed so that the ratio of Y and Al in the thin film was 7:3 to 6:4. The total thickness of the manufactured thin film was 5 to 5.5 ㎛.

In addition, the deposition conditions of the seed layer and thin film were the same as in Experimental Example 1, and the manufactured thin film specimens were heat-treated at a temperature of 900 to 1200°C for 1 to 3 hours. Since rapid temperature changes may cause peeling of the substrate and the coating layer, the heating rate was maintained in the range of 2 to 5°C/min.

<Comparative Example 2>

A YAM thin film was formed using the same method as in Example 2, but the seed layer formation process was omitted.

The deposition conditions applied to each source during deposition of the seed layer and thin film of Example 2 and Comparative Example 2 are summarized in Table 2 below.

division Coating Source Evaporation rate
(Å/s) Deposition thickness
(㎛) Deposition material ratio
(%) Comparative Example 2 _Y2O3 ( _thin film) 2.0~3.0 2.0~3.0 20~40 Al ₂ O ₃ (thin film) 1.0~2.0 1.0~2.0 60~80 Example 2 Al ₂ O ₃ (seed) 1.0~2.0 0.4~0.5 5~10 _Y2O3 ( _thin film) 2.0~3.0 3.0~4.0 50~85 Al ₂ O ₃ (thin film) 1.0~2.0 1.0~2.0 10~45

EDS analysis and XRD analysis were performed on the specimens manufactured in Example 2 and Comparative Example 2.

Figures 18 (a) and (b) are graphs showing the results of EDS analysis before and after heat treatment of the thin film specimen produced in Comparative Example 2, respectively.

Referring to Fig. 18, it can be seen that the contents of Y, Al, and O are generally maintained uniformly from the surface to the interior. From the EDS analysis results, the Al, Y, and O atomic fractions in the thin film were calculated to be approximately 14.63 at%, 32.07 at%, and 53.30 at%, respectively, before heat treatment, and 13.45 at%, 33.77 at%, and 50.78 at% after heat treatment.

Figures 19 (a) and (b) are graphs showing the results of XRD analysis before and after heat treatment of a thin film specimen deposited in Comparative Example 2.

Referring to Fig. 19, it can be seen that the thin film, which existed mainly in an amorphous state before heat treatment, undergoes crystallization through heat treatment. In the XRD pattern, the main peaks of the YAM crystallite are the (122) peak and the (023) peak around 2θ= ₂₉ ~ ₃₁ °, and in addition, _Y2O3 and _Al2O3 phases can be confirmed.

Figure 20 is a photograph of the surface of a specimen deposited in Comparative Example 2 before and after heat treatment.

Referring to Fig. 20, a crater structure is observed on the surface of the specimen of Comparative Example 2 after heat treatment.

Figures 21 (a) and (b) are graphs showing the results of EDS analysis before and after heat treatment of the thin film specimen manufactured in Example 2, respectively.

From the electron microscope image of Fig. 21, it can be seen that a seed layer is formed between the substrate and the thin film, and from the EDS analysis results, it can be confirmed that each element is uniformly distributed throughout the entire thickness of the thin film.

Figures 22 (a) and (b) are graphs showing the results of XRD analysis of the thin film specimen deposited in Example 2 before and after heat treatment.

Referring to Fig. 22, it can be seen that the thin film specimen manufactured in Example 2 existed in an amorphous phase before heat treatment, and was substantially converted into a YAM single crystal phase through heat treatment.

Figure 23 is a photograph of the surface of a specimen deposited in Example 2 before and after heat treatment.

Referring to Fig. 23, it can be seen that the specimen of Example 2 has a stable surface structure.

Figure 24 (a) is a graph showing the results of hardness measurements before and after heat treatment of thin film specimens of Comparative Example 2 (denoted as YAM) and Example 2 (denoted as Hybrid-YAM), and (b) is a graph showing the results of bonding strength measurements before and after heat treatment of thin film specimens of Comparative Example 2 and Example 2.

Referring to Figure 24, it can be seen that the thin film specimen of Example 2 exhibits slightly improved hardness and bonding strength compared to Comparative Example 2.

Below, the experimental results of heat treatment at different temperatures for Example 2 are described in detail.

Figure 25 is a photograph of the surface of a thin film specimen manufactured according to Example 2 of the present invention taken at each heat treatment temperature section.

The total thickness of the manufactured thin film was 5.0 μm, and the images were taken using an optical microscope at a magnification of 100 times (400 times in Fig. 25f). Fig. 25a is a specimen that was not heat-treated (0°C), and Figs. 25b, 25c, 25d, 25e, and 25f are photographs of specimens that were heat-treated at heat treatment temperatures of 800°C, 900°C, 1,000°C, and 1,100°C (magnification of 100 times), and 1,100°C (magnification of 400 times) for 1 to 2 hours, respectively.

Generally, YAM crystallizes at lower temperatures than YAG. At heat treatment temperatures of 800℃, 900℃, and 1,000℃, no problems such as cracks on the surface of the specimen occurred. On the other hand, at 1,100℃, cracks occurred in craters and throughout the film.

Figure 26 is a graph showing the results of measuring hardness according to heat treatment temperature range of a thin film specimen manufactured according to Example 2 of the present invention.

The hardness was measured to be 9.01 GPa when no heat treatment was performed (0℃). At heat treatment temperatures of 800℃ and 900℃, the hardness was 10.86 GPa and 12.61 GPa, respectively, confirming a tendency for the hardness to increase. This is expected to be due to the increase in hardness caused by the phase bonding of YAM due to the heat treatment, compared to the case where no heat treatment was performed. At 1,000℃, it was measured to be 12.39 GPa, a level similar to the hardness at 900℃. On the other hand, it decreased to 7.67 GPa at 1,100℃. Therefore, it can be seen that as the temperature increases further above 1,100℃, cracks occur in the thin film, showing a tendency for the hardness to decrease.

Figure 27 is a graph showing the results of measuring the crystallite size according to the heat treatment temperature range of a thin film specimen manufactured according to Example 2 of the present invention.

The crystal size was measured to be 1.54 nm and 1.44 nm at 0℃ and 800℃, respectively. It significantly increased to 23.70 nm, 23.60 nm, and 25.50 nm at 900℃, 1,000℃, and 1,100℃, respectively. Therefore, it can be seen that crystallization occurred at 900℃, 1,000℃, and 1,100℃.

Figure 28 is a graph showing the results of XRD analysis by heat treatment temperature range of a thin film specimen manufactured according to Example 2 of the present invention.

XRD analysis results show that the thin film exists in an amorphous phase at 0℃ and 800℃, and crystallization progresses into a YAM crystal phase at 900℃, 1,000℃, and 1,100℃. At 900℃, a mixed state of YAG and YAP is confirmed, and this was confirmed to be a mixed phase during the crystallization process.

As described above, in the case of YAM, it can be seen that the crystallization reaction occurs at a heat treatment temperature of more than 800°C and less than 1,100°C, preferably more than 900°C and less than 1,100°C, and more preferably about 1,000°C, and the properties of the thin film are improved. Here, “about” can indicate a deviation of ±5%.

Below, we describe the changes in the properties of YAG and YAM thin films according to changes in the material of the seed layer. Among the experimental conditions of the examples below, those that are identical to the experimental conditions described above are omitted.

<Example 3>

An Al ₂ O ₃ seed layer identical to that in Example 1 was formed. At this time, the thickness of the Al ₂ O ₃ seed layer can be adjusted to 0.10 to 0.15 μm. A YAG thin film with a thickness of 5.0 μm was formed on the seed layer by co-deposition in the same manner as in Example 1.

<Comparative Example 3>

Comparative Example 3 is the same as Example 3 except that the seed layer is a Y ₂ O ₃ seed layer.

Figure 29 is a photograph of the surface of a thin film specimen manufactured according to Comparative Example 3 before and after heat treatment.

The heat treatment was performed at 1,000°C to 1,100°C. Referring to the optical microscope photographs and SEM photographs of Fig. 29, the shape of large particles is observed on the surface of the thin film before the heat treatment, and surface cracks and boundary cracks due to the large particles were observed after the heat treatment. When the particle size on the surface of the thin film was measured in the SEM photograph, it was 1,767 nm before the heat treatment and slightly decreased to 1,500 nm after the heat treatment. On the other hand, in the case of Example 3, the size of the surface particles was observed to be 76 nm before the heat treatment and 74 nm after the heat treatment, which was much smaller than in Comparative Example 3.

Therefore, it can be seen that the grain growth of the thin film differs depending on the material of the seed layer. In addition, in the case of the Y ₂ O ₃ seed layer, cracks occur on the surface of the crystallized thin film, so not only can the thin film be peeled off, but problems may also occur in processes required for the 3-component thin film, such as plasma etching, diffusion barrier formation, and physical ion etching.

In the case of the _{Y2O3 seed} layer, larger particles are grown _compared to _Al2O3 , and the YAG thin film is also composed of large particles due to the particles grown in _{the Y2O3} seed layer. Therefore, in the case of Comparative Example 3, which is composed of relatively large particles, it is expected that cracks occurred at the interface between particles that are vulnerable to phase bonding during the crystallization process by heat treatment.

Figure 30 is a graph showing the crystallite size after heat treatment in Example 3 and Comparative Example 3.

Referring to FIG. 30, the crystal size of Example 3 (Al ₂ O ₃ Seed-YAG) is 18.1 nm, and the crystal size of Comparative Example 3 (Y ₂ O ₃ Seed-YAG) is 18.7 nm, showing that the crystallization degrees of Example 3 and Comparative Example 3 are similar.

Figure 31 is a graph showing the results of hardness measurements after heat treatment in Example 3 and Comparative Example 3.

Referring to FIG. 31, the hardness of Example 3 (Al ₂ O ₃ Seed-YAG) is 20.30 GPa, and the hardness of Comparative Example 3 (Y ₂ O ₃ Seed-YAG) is 19.73 GPa, showing that the hardness of Example 3 and Comparative Example 3 are similar.

Figure 32 is a graph showing the results of adhesion measurement after heat treatment of Example 3 and Comparative Example 3.

Referring to FIG. 32, the bonding strength of Example 3 (Al ₂ O ₃ Seed-YAG) is 20.60 N, and the bonding strength of Comparative Example 3 (Y ₂ O ₃ Seed-YAG) is 8.31 N, showing that the bonding strength of Example 3 is greater. This is expected to be because, due to the large particles generated in the Y ₂ O ₃ seed layer of Comparative Example 3 during the crystallization process, cracks occurred on the surface of the thin film and the adhesion with the substrate was reduced.

Figure 33 is a graph showing the results of XRD analysis after heat treatment of Example 3 and Comparative Example 3.

Fig. 33a is a graph of Example 3, and Fig. 33b is a graph of Comparative Example 3. In both Example 3 and Comparative Example 3, a peak of YAG crystal quality was confirmed. In the case of Comparative Example 3, the peak intensity was measured as 5,000, which is due to the effect of the particle size and crystallization degree on the surface of the thin film. Therefore, it can be seen that the properties of the thin film in Comparative Example 3 are not as stable as in Example 3.

<Example 4>

An Al ₂ O ₃ seed layer identical to that in Example 1 was formed. At this time, the thickness of the Al ₂ O ₃ seed layer can be adjusted to 0.10 to 0.15 μm. A YAM thin film with a thickness of 5.0 μm was formed on the seed layer by co-deposition in the same manner as in Example 1.

<Comparative Example 4>

Comparative Example 4 is the same as Example 4 except that the seed layer is a Y ₂ O ₃ seed layer.

Figure 34 is a photograph of the surface of a thin film specimen manufactured according to Comparative Example 4 before and after heat treatment.

The heat treatment was performed at 1,000°C to 1,100°C. Referring to the optical microscope image of Fig. 34, craters were observed on the surface of the thin film after the heat treatment. These craters may cause cracks to occur on the surface of the thin film, causing the thin film to peel off.

Figure 35 is a graph showing the crystallite size after heat treatment of Example 4 and Comparative Example 4.

Referring to Figure 35, the crystal size of Example 4 (Al ₂ O ₃ Seed-YAM) is 24.90 nm, and the crystal size of Comparative Example 4 (Y ₂ O ₃ Seed-YAM) is 23.16 nm, indicating that the degree of crystallization of Example 4 is high.

Figure 36 is a graph showing the results of hardness measurements after heat treatment in Example 4 and Comparative Example 4.

Referring to FIG. 36, the hardness of Example 4 (Al ₂ O ₃ Seed-YAM) is 13.80 GPa, and the hardness of Comparative Example 4 (Y ₂ O ₃ Seed-YAM) is 13.49 GPa, showing that the hardness of Example 4 and Comparative Example 4 are similar.

Figure 37 is a graph showing the results of adhesion measurements after heat treatment in Example 4 and Comparative Example 4.

Referring to FIG. 37, the bonding strength of Example 4 (Al ₂ O ₃ Seed-YAM) is 11.20 N, and the bonding strength of Comparative Example 4 (Y ₂ O ₃ Seed-YAM) is 10.88 N, showing that the bonding strength of Example 4 is greater. This is expected to be due to the reduced adhesion due to the crater-shaped surface cracks formed in the Y ₂ O ₃ seed layer of Comparative Example 4.

Figure 38 is a graph showing the results of XRD analysis after heat treatment of Example 4 and Comparative Example 4.

Fig. 38a is a graph of Example 4, and Fig. 38b is a graph of Comparative Example 4. In both Example 4 and Comparative Example 4, peaks of YAM crystals were confirmed. In the case of Comparative Example 4, three crystals of Al ₂ O ₃ , Y ₂ O ₃ , and YAM were observed in a mixed form, and Al ₂ O ₃ and Y ₂ O ₃ were measured to have low peak intensities. In the case of Comparative Example 4, it is expected that the bonding between the seed layer and the parent material was not good due to cracks on the surface and a decrease in the bonding strength between the Y ₂ O ₃ seed layer and the parent material during the phase bonding process.

As described above, in Comparative Example 4, the bonding strength with the parent material decreases during the heat treatment process, craters occur on the surface, and the thin film becomes unstable and may not form a single YAM crystal.

Although the present invention has been described above through exemplary embodiments and drawings, these have been provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and those with ordinary skill in the art to which the present invention pertains will appreciate that various modifications and variations are possible without departing from the essential characteristics of the present invention. Therefore, the spirit of the present invention should not be limited to the described embodiments, and all technical ideas that are equivalent or equivalent to the scope of the claims, as well as the scope of the patent claims, should be interpreted as being included in the scope of the rights of the present invention.

Claims (11)

A method for electron beam ion assisted deposition of a Y-Al-O compound thin film on a substrate placed in an electron beam ion assisted deposition device, A step of loading an aluminum source into a first holder of an electron beam evaporator of the above deposition device, and loading an yttrium source into a second holder; A step of forming a seed layer by ion beam assisted deposition of the aluminum source evaporated in the first holder of the electron beam evaporator onto the substrate; and An electron beam ion assisted deposition method, comprising the step of forming a Y-Al-O layer on the seed layer by performing ion assisted deposition while simultaneously evaporating the yttrium source and the aluminum source in the first holder and the second holder of the electron beam evaporator. In the first paragraph, An electron beam ion assisted deposition method, wherein the Y-Al-O compound comprises at least one selected from the group consisting of YAG, YAM and YAP. In the first paragraph, An electron beam ion assisted deposition method, wherein the yttrium source comprises Y ₂ O ₃ . In the third paragraph, An electron beam ion assisted deposition method, wherein the aluminum source comprises Al ₂ O ₃ . In the first paragraph, After the Y-Al-O layer formation step, An electron beam ion assisted deposition method further comprising a step of heat treating the Y-Al-O layer. In paragraph 5, An electron beam ion assisted deposition method in which the above Y-Al-O layer heat treatment step is performed at 900 to 1200°C. In paragraph 5, An electron beam ion assisted deposition method, wherein the above Y-Al-O layer is a YAG layer, and the heat treatment step is performed at 1,000°C or higher and 1,200°C or lower. In paragraph 5, An electron beam ion assisted deposition method, wherein the above Y-Al-O layer is a YAM layer, and the heat treatment step is performed at more than 900°C and less than 1,100°C. Al ₂ O ₃ seed layer on the substrate; and An electron beam ion assisted coating comprising a crystalline Y-Al-O layer on the seed layer. In Article 9, The above Y-Al-O layer is an electron beam ion assisted coating containing YAG. In Article 9, The above Y-Al-O layer is an electron beam ion assisted coating including YAM.

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