KR20150124901A - Dielectric thin films based Calcium Copper Titanate and method for fabricating the same - Google Patents

Abstract

The present invention relates to a calcium-copper-titanium oxide-based dielectric thin-film having a high dielectric constant and low dielectric loss properties and a manufacturing method thereof. According to the present invention, the dielectric thin-film is prepared by mixing a dielectric thin-film with CaxCuyTizO_12 (0<x<2, 2<y<4, 3<z<5), CuO, and TiO_2. The atomic ratio of Ca, Cu, and Ti in the dielectric thin-film can be represented as: Ca:Cu:Ti=0.6-1.4:2.9-3.8:4.5.

Description

TECHNICAL FIELD [0001] The present invention relates to a dielectric thin film based on calcium copper titanium oxide and a method for fabricating the dielectric thin film.

The present invention relates to a dielectric thin film based on calcium copper-titanium oxide and a method for manufacturing the same. More particularly, the present invention relates to a dielectric thin film based on calcium copper-titanium oxide having a high dielectric constant and a low dielectric loss property.

Background Art [0002] Recently, researches for reducing the size of electronic devices have been actively conducted along with the development of electronic devices. In the field of dielectrics, silicon oxide (SiO ₂ ), which is used as a gate oxide of a conventional metal oxide semiconductor field effect transistor (MOSFET) or as a dielectric of a capacitor, has reached the limit of integration required in the electronic device industry A large number of studies have been conducted on the high-permittivity thin film for the purpose of improving the dielectric constant.

When a high-k film is used for the gate oxide film, the leakage current can be reduced while reducing the equivalent oxide thickness (EOT) and the device can be driven at a low voltage, thereby increasing the integration and efficiency of the device. As the dielectric used in the capacitor is miniaturized, research for increasing the electrostatic capacity equal to or larger than the capacitance that has been secured in the past is getting more and more necessary. For this purpose, many attempts have been made to secure a capacitance by securing a capacitance through a nano-laminate structure in which a dielectric thin film is stacked or by applying a new high-permittivity material.

Generally, materials having a perovskite structure are known to have high permittivity due to easy ferroelectricity because they have spontaneous polarization. But material such as BaTiO _3, MgSnO _3, SrTiO ₃ and _{Pb (Mg 1/3 Nb 2/3) O} 3 , which has a ferroelectric phase transition has occurred in accordance with the change of temperature and dielectric properties decline, so a bit in the electronics industry Requires a dielectric material having a high dielectric constant and stable to further temperature changes.

Since CaCu ₃ Ti ₄ O ₁₂ (hereinafter referred to as CCTO) stably maintains a phase without distortion of the lattice in a relatively wide temperature range (100-400 K) and maintains a high dielectric constant even in a wide frequency range below 100 kHz, (SiO ₂ ) has been studied as a material for substitution. Recently, in order to further improve the high dielectric constant of CCTO, a study has been conducted to improve the characteristics of the material by inducing the change of the oxidation number and the electric conductivity through the doping of a new element, or to improve the dielectric property by changing the deposition condition in the formation of the dielectric thin film .

U.S. Patent No. 7830644 discloses that CCTO can be applied as a dielectric layer of a capacitor to obtain a dielectric constant of 1000 to 1500 at a frequency of 1 kHz. According to another study, the dielectric characteristics of the CCTO were evaluated according to the atmosphere during the heat treatment of the CCTO. Specifically, changes in the dielectric properties were evaluated in each of the vacuum, oxygen, nitrogen and atmospheres, and a dielectric constant of 410 at a frequency of 10 kHz (Journal of Electronic Materials, Vol. 38, Issue 3, 453-459 (2009)).

Conventional CCTO studies have focused on adding new elements to improve the dielectric properties of CCTO or applying specific process conditions during heat treatment, which limits the improvement of dielectric properties.

U.S. Patent No. 7830644

Journal of Electronic Materials, Vol. 38, Issue 3, 453-459 (2009)

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a dielectric thin film based on calcium copper-titanium oxide having a high dielectric constant and a low dielectric loss property.

In order to achieve the above object, the dielectric thin film of calcium copper-titanium oxide according to the present invention has a dielectric thin film of Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y <4, 3 <z < , CuO, and TiO ₂ , and the atomic composition ratio of Ca, Cu, and Ti in the dielectric thin film is Ca: Cu: Ti = 0.6 to 1.4: 2.9 to 3.8: 4.5.

The atomic composition ratio of Ca, Cu, and Ti may be Ca: Cu: Ti = 0.9: 3.2: 4.5. The Ca _x Cu _y Ti _z O ₁₂ may be CaCu ₃ Ti ₄ O ₁₂ .

The present invention also provides a method of manufacturing a thin film of calcium-copper-titanium oxide-based dielectric thin film, comprising the steps of simultaneously sputtering a CuTiO ₃ target and a CaTiO ₃ target to form a thin film of Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y <<z<5), CuO and TiO ₂ are prepared by mixing the dielectric thin film, and the atom composition ratio of Ca, Cu, Ti in said dielectric thin film Ca: Cu: is 4.5: Ti = 0.6~1.4: 2.9~3.8 .

The method of claim ₁ , further comprising: preparing a substrate having a lower electrode; sputtering a CuTiO ₃ target and a CaTiO ₃ target simultaneously to form a thin film of Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y < 4, 3 < z < 5), forming a dielectric thin film in which CuO and TiO ₂ are mixed, separating a plurality of upper electrodes on the dielectric thin film to complete a plurality of capacitor structures, And a step of measuring a constituent material and an atomic composition ratio of the dielectric thin film of the specific capacitor structure to measure an atomic composition ratio of Ca: Cu: Ti: Ca: Cu: Ti = 0.6 to 1.4: 2.9 to 3.8 : 4.5. &Lt; / RTI &gt;

The calcium-copper-titanium oxide-based dielectric thin film according to the present invention has the following effects.

It can be effectively applied to MIM capacitors, multilayer ceramic capacitors (MLCC), MOSFETs, and flexible TFTs because it has a dielectric property corresponding to or higher than that of CCTO (CaCu ₃ Ti ₄ O ₁₂ ). In addition, it is possible to manufacture a dielectric thin film through a relatively simple process in preparation for a conventional dielectric thin film manufacturing method, thereby reducing manufacturing costs.

1 is a schematic diagram of a sputtering apparatus for forming a dielectric thin film based on calcium copper-titanium oxide according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating a method of manufacturing a dielectric thin film based on calcium copper-titanium oxide according to an embodiment of the present invention. FIG.
3 is a reference view showing a MIM structure including a dielectric thin film of calcium copper-titanium oxide based on an embodiment of the present invention.
4 is a graph showing the thickness of the dielectric thin film according to the position of the dielectric thin film prepared in Example 1. FIG.
FIG. 5 is a graph showing dielectric characteristics according to the position of a dielectric thin film prepared in Example 1. FIG.
6 is a graph showing the results of X-ray photoelectron spectroscopic analysis according to the position of the dielectric thin film prepared in Example 1. FIG.
7 is a transmission electron microscopic analysis result of the dielectric thin film prepared in Example 1. FIG.
FIG. 8 is a graph showing impedance analysis results according to the position of the dielectric thin film produced in Example 1. FIG.
FIG. 9 shows X-ray diffraction analysis results of the dielectric thin films prepared in Example 1. FIG.
10 is an experimental result showing the atomic composition ratio according to the position of the dielectric thin film prepared in Example 1. FIG.
FIG. 11 is a reference view showing frequency-dependent dielectric properties at respective points of a dielectric thin film produced through Example 1. FIG.

The present invention provides a technique for a dielectric thin film in which Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y <4, 3 <z <5), copper oxide and titanium oxide are mixed. In the dielectric thin film in which Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y <4, 3 <z <5), copper oxide and titanium oxide are mixed, calcium (Ca) Cu) and titanium (Ti) in order to achieve excellent dielectric properties of the dielectric thin film.

As described above in the Background of the Invention, CCTO (CaCu ₃ Ti ₄ O ₁₂ ) has a property of maintaining a high dielectric constant in a wide frequency region. The present invention is characterized in that Ca _x Cu _y Ti _z O ₁₂ A dielectric thin film is formed by mixing copper oxide and titanium oxide in a dielectric thin film and dielectric material having a dielectric property twice as high as that of CCTO through the optimum atomic composition ratio of calcium (Ca), copper (Cu), and titanium (Ti) Thin film.

The atomic composition ratio of the combination of the constituent elements (Ca _x Cu _y Ti _z O ₁₂ , copper oxide and titanium oxide) constituting the dielectric thin film of the present invention and the dielectric thin film is supported by experiments. In one embodiment, a thin film layer having a continuous composition is formed through a sputtering method using CuTiO ₃ and CaTiO ₃ as a target. The thin film layer is divided into a plurality of regions and dielectric properties are measured for the thin film layers in each region. A dielectric thin film having a composition ratio is specified. The dielectric properties of the thin film layer in each region can be measured by forming the thin film layer on a substrate provided with a conductor (lower electrode) and forming an upper electrode on the thin film layer in each region to form a metal-insulator-metal And the dielectric property of each MIM structure is measured in a completed state.

A specific method for specifying a dielectric thin film having an optimum combination and an optimal composition ratio proceeds as follows (see FIG. 2).

First, a thin film layer having a continuous composition is formed (S202). A sputtering method can be used for the deposition of the thin film layer. In the case of using the sputtering method, the CuTiO ₃ target and the CaTiO ₃ target are horizontally opposed to each other, and the CuTiO ₃ target and the CaTiO ₃ target are sputtered while the substrate is provided between the CuTiO ₃ target and the CaTiO ₃ target, To form a thin film layer.

FIG. 1 is a schematic view of a sputtering apparatus for forming a dielectric thin film based on calcium copper-titanium oxide according to an embodiment of the present invention. Referring to FIG. 1, A CuTiO ₃ target, and a CaTiO ₃ target, and a substrate is mounted on a lower portion of the chamber. In addition, the CuTiO ₃ target and the CaTiO ₃ target are horizontally opposed to each other, and each target is provided with a sputter gun. In this state, when argon (Ar) and oxygen (O ₂ ) are supplied into the chamber and power is applied to the sputter gun to generate plasma, the discharged argon ions collide with the CuTiO ₃ target and the CaTiO ₃ target, Is deposited on the substrate, and the deposited target material forms a thin film layer.

The phases that can be formed by the target material of the CuTiO ₃ target and CaTiO ₃ target are Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y <4, 3 <z <5) ₃ , and TiO ₂ . That is, the thin film layer formed by the sputtering of the CuTiO ₃ target and the CaTiO ₃ target is composed of Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y <4, 3 <z <5), CuO, CaTiO ₃ , TiO is composed of any one or more of the mixture of the _two. Many of the content on the substrate adjacent to the target CuTiO ₃ CuO and TiO _2, is often relatively content of CaTiO ₃ formed on the substrate adjacent the CaTiO _3, the content of Ca _x Cu _y Ti _z O ₁₂ relatively high on the substrate center. Further, the thickness of the thin film layer formed on the substrate portion adjacent to the target is relatively larger than the thickness of the thin film layer formed on the substrate central portion.

The content of each of Ca _x Cu _y Ti _z O ₁₂ , CuO, CaTiO ₃ , and TiO ₂ in the thin film layer is varied not only by the distance between the substrate and the target but also by the voltage applied to the CuTiO ₃ target and the CaTiO ₃ target. Increasing the voltage applied to the CuTiO ₃ target sputter guns and relatively reduce a voltage applied to the CaTiO ₃ target sputter gun in the amount of CuO and TiO ₂ is increased content of CaTiO ₃ is the smaller, Ca _x Cu _y Ti _z The Cu content at O ₁₂ is increased. Conversely, reducing the voltage applied to the CuTiO ₃ target sputter guns and when relatively increases the voltage applied to the CaTiO ₃ target sputter gun in the content of CaTiO ₃ is increased content of CuO and TiO ₂ is the smaller, Ca _x Cu _y The Ca content in Ti _z O ₁₂ is increased.

In summary, the thin film layer formed by sputtering is composed of a mixture of at least one of Ca _x Cu _y Ti _z O ₁₂ , CuO, CaTiO ₃ , and TiO ₂ , and depending on the distance between the target and the substrate and the voltage applied to the target, And the Ca content and the Cu content in the thin film layer are changed.

On the other hand, a conductor may be provided in advance on the surface of the substrate on which the thin film layer is deposited (S201), and a thin film layer is deposited on the conductor on the surface of the substrate. It plays a role. As the conductive material, platinum (Pt) may be used, and as the substrate, a silicon substrate coated with platinum (Pt) may be used.

In the state where the thin film layer is formed on the substrate through sputtering, the thin film layer is divided into a plurality of regions along the longitudinal direction of the thin film layer, and an upper electrode is formed on each region as shown in FIG. 3 (S203). Here, the longitudinal direction of the thin film layer means the longitudinal direction between the horizontally opposed CuTiO ₃ target and the CaTiO ₃ target. In order to crystallize the thin film layer, it is preferable that the substrate having the thin film layer formed before forming the upper electrode is subjected to rapid thermal annealing at a temperature of 700 to 800 ° C.

The reason why the upper electrode is formed on each region of the thin film layer is to measure the dielectric characteristics of the thin film layer in each region, and the vertically stacked upper electrode, thin film layer, and conductor (lower electrode) -metal capacitor structure. The upper electrode may be formed by forming a mask exposing a thin film layer at a site where a top electrode is to be formed through a photolithography process, then laminating a metal material on the thin film layer including the mask, .

The upper electrode is provided on each region of the thin film layer, and the dielectric constant of each region of the thin film layer is measured in a state where each region has an MIM capacitor structure (S204). Specifically, the capacitance is measured by applying power to the upper electrode and the lower electrode of the MIM capacitor, and then the capacitance value, the thickness of the thin film layer in each region, and the area of the thin film layer in each region are substituted into Equation 1 below And the dielectric constant of the thin film layer in each region is calculated. At this time, the capacitance value can be measured by an impedance meter, and the thickness and the area of the thin film layer can be confirmed by a scanning electron microscope (SEM).

(Equation 1)

(Where C is the capacitance of the thin film layer in each region,? ₀ is the permittivity in vacuum,? _R is the permittivity of the thin film layer in each region, A is the area of the thin film layer in each region, and d is the thickness of the thin film layer in each region)

Through the above-described process, the dielectric constant of the thin film layer in each region can be measured, and the thin film layer in the region having a good dielectric constant value can be specified. In this state, the composition of the thin film layer and the atomic composition ratio of the thin film layer can be confirmed by analyzing the kind of the compound forming the thin film layer and analyzing the atomic composition of the thin film layer with respect to the thin film layer having an excellent dielectric constant value (S205). The composition of the thin film layer can be confirmed by X-ray diffraction (XRD), and the atomic composition ratio of the thin film layer can be confirmed by Rutherford backscattering spectroscopy (RBS).

The present invention specifies dielectric thin films having a combination of the following constituent materials and an optimum atomic composition ratio as dielectric thin films having excellent dielectric constants and the reason for limiting the numerical values for the optimum combination of the constituent materials and the optimum atomic composition ratio of the thin film layer is as follows: &Lt; / RTI &gt;

The dielectric thin film according to the present invention is a mixture of Ca _x Cu _y Ti _z O ₁₂ , CuO and TiO ₂ , and the atomic composition ratio of Ca, Cu and Ti in the dielectric thin film is Ca: Cu: Ti = 0.6 to 1.4: 2.9 to 3.8: 4.5. The dielectric constant and the dielectric loss value of CCTO are 330 and 0.52, respectively. The dielectric characteristics of the dielectric thin film according to the present invention are superior to those of CCTO. In particular, the atomic composition ratio of Ca, Cu, and Ti in the dielectric thin film of the present invention Has a dielectric constant of about 781 and a dielectric loss value of 0.56 when Ca: Cu: Ti = 0.9: 3.2: 4.5.

Next, the calcium-titanium-oxide-based dielectric thin film according to the present invention will be described in more detail with reference to examples.

&Lt; Example 1: Production of dielectric thin film >

A substrate coated with platinum (Pt) is provided in a chamber of a horizontally opposed continuous compositions-spread sputtering device, and a sputtering process is performed in a state where a horizontally opposed CuTiO ₃ target and a CaTiO ₃ target are mounted. And a dielectric thin film was formed on the substrate. At this time, the target (target CuTiO ₃ and CaTiO ₃ target) and was set to 9mm distance between the substrate and the Ar and O _2, 8 to the inside of the chamber pressure reaches two ㅧ 10 ^-6 Torr time: mixture injected into the second And the working pressure was adjusted to ² 10 ^-2 Torr. During the deposition, the temperature of the substrate was maintained at 500 ° C, and a power of 70 W was applied to the CuTiO ₃ target and the CaTiO ₃ target, respectively, and sputtering was performed for 3 hours. After the deposition of the dielectric thin film was completed, the dielectric thin film was crystallized by rapid thermal treatment at 750 ° C for 10 minutes.

In the dielectric thin film formed state, a 200 ㅧ 200㎛ platinum of the ^second size (Pt) upper electrode 500 with 1.5mm spacing in the longitudinal direction on the dielectric thin film was formed to a thickness of 100nm by a DC sputtering.

&Lt; Example 2: Thickness change of thin film according to position >

The change in the thickness of the dielectric thin film according to the position of the dielectric thin film prepared in Example 1 was measured. FIG. 4 is a graph showing a thickness of a thin film according to a position of a dielectric thin film prepared in Example 1, and was measured by a scanning electron microscope (SEM). In order to determine the thickness of the dielectric thin film according to the position, the dielectric thin film was divided into 10 mm intervals in the longitudinal direction, and each point was named as P1 to P7. Further, when using FIG. 4, 'CuTiO _3' when labeled graph is used only CuTiO ₃ target on the target during sputtering, and the graph denoted by 'CaTiO _3' is only CaTiO ₃ target on the target during sputtering, 'CCS films Quot; indicates a case where both a CuTiO ₃ target and a CaTiO ₃ target are used as a target during sputtering.

Referring to FIG. 4, when the CuTiO ₃ target and the CaTiO ₃ target are both used (refer to 'CCS films'), the thickness of the thin film (P1 and P7) increases toward the target and increases toward the center of the substrate (P2 to P6) As shown in FIG. 4, the maximum thickness is 350 nm of P1, and the minimum thickness is 200 nm between P6 and P7.

&Lt; Example 3: Dielectric properties of dielectric thin films according to their positions >

Dielectric properties of the dielectric thin films prepared in Example 1 were measured according to their positions. As described in Example 1, 500 upper electrodes were formed at intervals of 1.5 mm on the dielectric thin film. The capacitance value (C) was measured through an impedance analyzer for 500 points where the upper electrode was formed, The dielectric constant was calculated using the capacitance value and the thickness (d) and the area (A) of the dielectric thin film at each point, and the results are shown in FIG.

Referring to FIG. 5, it can be seen that the dielectric constant is changed according to the position of the dielectric thin film. The dielectric thin film of the present invention changes not only the thickness of the thin film but also the composition and composition of the dielectric thin film depending on the position. The result of FIG. 4 shows that although the thickness of the dielectric thin film is almost unchanged on the central portion of the substrate, the change in the dielectric constant of the dielectric thin film on the central portion of the substrate is large in the result of FIG. It can be seen that it is affected more greatly.

From the results of FIG. 5, it was confirmed that the dielectric constant sharply rises around P3, and specifically shows a dielectric constant of about 781 and a dielectric loss of 0.56 at the point P3. The permittivity and dielectric loss values of CCTO are 330 and 0.52, respectively, and the permittivity is relatively low when the decrease in dielectric loss value is small.

&Lt; Example 4: Chemical, structural and electrical properties of dielectric thin films according to their positions >

The constituent materials of the dielectric thin films prepared in Example 1 were analyzed by X-ray photoelectron spectroscopy, transmission electron microscopy, EDS (energy dispersive spectroscopy) and impedance method. Referring to FIG. 6, it can be seen that the Cu ⁺ ion has a more significant meaning at P3 than CaCu ₃ Ti ₄ O ₁₂ . The ratio of Cu ⁺ / Cu ²⁺ and Ti ³⁺ / Ti ⁴⁺ increases at P3, which is related to the formation of defects such as oxygen vacancy, It can be seen that creating an environment that can be easily moved. Further, FIG. 7, in the P3 grain boundary content of Cu be seen that the more abundant than the CaCu ₃ Ti ₄ O _12, and an excess of Cu this is precipitated along the grain boundary as well as the grain boundary as the growth of the particles It can be seen that the speed is controlled chemically and structurally. Referring to FIG. 8, it can be seen that other compositions except for P3 and CaCu ₃ Ti ₄ O ₁₂ do not show a cole-cole plot, and only the composition of P ₃ and CaCu ₃ Ti ₄ O ₁₂ are influenced by Cu grain boundaries.

&Lt; Example 5: Constituents of dielectric thin film according to position >

The constituent materials of the dielectric thin films prepared in Example 1 were analyzed by X-ray diffraction analysis. Referring to FIG. 9, it can be seen that the dielectric thin films at the respective points P1 to P7 are composed of a mixture of at least one of Ca _x Cu _y Ti _z O ₁₂ , CuO, CaTiO ₃ and TiO ₂ . Because also it was only in Ca _x Cu _y Ti _z O ₁₂ eseo _{6 CCTO (CaCu 3 Ti 4 O} 12) shown, which does not exist in the X- ray diffraction data for the Ca _x Cu _y Ti _z O ₁₂ except CCTO, On the other hand, it is also because the content of CCTO among the various compositions of Ca _x Cu _y Ti _z O ₁₂ constituting the dielectric thin film is the largest.

9, if the dielectric thin film of a P3 point of the dielectric constant is the highest, and most similar to the CCTO crystal phase, it can be seen that the CuO and TiO ₂ is mixed a small amount. Therefore, in the case of the dielectric thin film at the point P3, it is presumed that the characteristic of CCTO plays a major role and that CuO and TiO ₂ mixed in a small amount contribute to the improvement of the dielectric constant by inducing the change of grain boundary and electric conduction characteristic . Further, it can be seen that the crystal phase of CCTO is decreased and the crystal phase of CuO, TiO ₂ and CaTiO ₃ is increased as the distance from the point P3 is increased. In connection with the result of FIG. 5, the secondary phases, that is, CuO, TiO ₂ and CaTiO ₃ It can be seen that as the crystal phase is increased, the dielectric properties are lowered. The diffraction pattern of CCTO was observed at all positions except P7, and appeared mainly at P2 to P5. In addition, the diffraction pattern of the thin film showed a tendency to appear similar to that of the target as the film was closer to each target. P6 and P7 are mainly CaTiO ₃ diffraction patterns, and it can be seen that the closer to P7 the dielectric constant of 150 to 160 is similar to that of CaTiO ₃ (see FIG. 5). In the case of P1, the diffraction pattern of CuO and TiO ₂ , which can be separated from CuTiO ₃ , appears mainly because no diffraction image of CuTiO ₃ is present. Near P3, nearly pure CCTO diffraction pattern was strongest. As a result of the diffraction pattern obtained at each point, the collapse of stoichiometry of CaCu ₃ Ti ₄ O ₁₂ due to the change of composition according to the distance of target and thin film In order to exist in the most stable form, various secondary phases such as CuO, TiO ₂ and CaTiO ₃ are formed in addition to the CaCu ₃ Ti ₄ O ₁₂ crystal phase, and they coexist together.

&Lt; Example 6: Atomic composition ratio of dielectric thin film according to position >

FIG. 10 shows the results of Rutherford backscattering spectroscopy (RBS) analysis of the atomic composition ratio of the dielectric thin films prepared in Example 1. FIG. Specifically, the atomic composition ratios of the dielectric thin films on the respective positions (P1 to P7) were obtained based on the measurement values obtained from the Rutherford backscattering spectroscopy (RBS) and the simulation results using the RUMP (Rutherford universal manipulation program).

Referring to FIG. 10, as the CaTiO ₃ target becomes closer to the CaTiO ₃ target, the Ca content increases, and the Cu content gradually increases near the CuTiO ₃ target. The tendency of the change in the atomic composition ratio at each point was similar to the result shown in Fig. 4 in which the thickness of the thin film varied with the distance between the target and the thin film, and was consistent with the change in the crystal phase obtained in the X- did.

In the case of the point P3, the atomic composition ratio of Ca, Cu and Ti is Ca: Cu: Ti = 0.9: 3.2: 4.5. In the point that the CCTO has an atomic composition ratio of 1: 3: 4, in the dielectric thin film on the atomic composition ratio of Ca _x Cu _y Ti _z O ₁₂ is nearly given the yirum pure CCTO of a small amount of CuO and TiO ₂ constituting the dielectric film of the P3 point addition CCTO dielectric thin Ca, Cu, Ti And can be deduced to have an atomic composition ratio of Ca: Cu: Ti = 0.9: 3.2: 4.5. Based on the results of the RBS analysis, it was confirmed that Cu and Ti were added in excess of 0.55 at% and 0.79 at%, respectively, in comparison with the atomic composition ratio of CCTO, at the point P3. On the other hand, at a point about 3 mm from the P3 point toward the CaTiO ₃ target, a point exactly coinciding with the CCTO composition was confirmed.

<Example 7: Dielectric properties of dielectric thin films according to positions>

FIG. 11 shows frequency-dependent dielectric properties at each point of the dielectric thin film prepared in Example 1. FIG. Referring to FIG. 11, it can be seen that the low dielectric constant is maintained regardless of the frequency change at the remaining points except P3 and CCTO. On the other hand, it can be seen that the dielectric thin films at the P3 and CCTO sites have a relatively high dielectric constant in the low frequency region of 1 kHz or less. In this region, P3 is about 1635 and CCTO is about 1290 have. Also, as the frequency increases, the dielectric constant gradually decreases. After 100 kHz, the dielectric constant decreases sharply, which is due to dielectric relaxation.

Referring to the results of Examples 1 to 6, it can be seen that the best dielectric characteristics are exhibited when the atomic composition ratio of Ca, Cu, and Ti in the dielectric thin film is Ca: Cu: Ti = 0.9: 3.2: And the dielectric thin film between P2 and P4, that is, Ca, Cu and Ti, has an atomic composition ratio of Ca: Cu: Ti = 0.6 to 1.4: 2.9 to 3.8: 4.5. can confirm.

Claims (7)

The dielectric thin film is made of a mixture of Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y <4, 3 <z <5), CuO and TiO ₂ ,
Wherein the dielectric thin film has a composition ratio of Ca: Cu: Ti = 0.6 to 1.4: 2.9 to 3.8: 4.5 in terms of an atomic composition ratio of Ca, Cu, and Ti in the dielectric thin film.
The dielectric thin film according to claim 1, wherein the atomic composition ratio of Ca, Cu, and Ti is Ca: Cu: Ti = 0.9: 3.2: 4.5.
The dielectric thin film according to claim 1, wherein the Ca _x Cu _y Ti _z O ₁₂ is CaCu ₃ Ti ₄ O ₁₂ .
The CuTiO ₃ target and the CaTiO ₃ target were simultaneously sputtered,
CuO and TiO ₂ are mixed with Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y <4, 3 <z <5)
Wherein the atomic composition ratio of Ca, Cu, and Ti in the dielectric thin film is Ca: Cu: Ti = 0.6 to 1.4: 2.9 to 3.8: 4.5.
5. The method according to claim 4, wherein the atomic composition ratio of Ca, Cu and Ti is Ca: Cu: Ti = 0.9: 3.2: 4.5.
5. The method of claim 4, wherein the Ca _x Cu _y Ti _z O ₁₂ is CaCu ₃ Ti ₄ O ₁₂ .
5. The method of claim 4,
Preparing a substrate provided with a lower electrode,
CuTiO ₃ target and CaTiO ₃ target were co-sputtered to form Ca _x Cu _y Ti _z O ₁₂ (0 <x <2, 2 <y <4, 3 <z <5), CuO and TiO ₂ Forming a mixed dielectric thin film,
Forming a plurality of capacitor structures by spacing a plurality of upper electrodes on the dielectric thin film;
Measuring dielectric properties of each capacitor structure; and
By measuring the constituent material and the atomic composition ratio of the dielectric thin film of the specific capacitor structure
Wherein a dielectric thin film having an atomic composition ratio of Ca, Cu, and Ti of Ca: Cu: Ti = 0.6 to 1.4: 2.9 to 3.8: 4.5 is specified.

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