KR101303853B1 - Method for formation ferroelectrics thin film and method for manufacturing device of planar structure - Google Patents

Abstract

The present invention relates to a method of forming a ferroelectric thin film and a method of manufacturing a planar structure element, a method of forming a ferroelectric thin film capable of forming (manufacturing) a ferroelectric thin film at a low temperature of less than 300 ℃, and a method of manufacturing a planar structure element using the same It is about. The present invention comprises the steps of (i) forming an amorphous pre-ferroelectric thin film on the substrate; And (ii) irradiating an excimer laser to the amorphous preliminary ferroelectric thin film, wherein in step (iii), the amorphous preferroelectric thin film is formed to a thickness of 50 nm or more, and in step (ii), the excimer Provided are a method of forming a ferroelectric thin film irradiating a laser at an energy density of 50 mJ / cm 2 to 200 mJ / cm 2 and at a frequency of 1 to 2,000 irradiation, and a method of manufacturing a planar structure element including the same. According to the present invention, a ferroelectric thin film can be formed (crystallized) at a low temperature of 300 ° C. or lower, and a device of planar structure is realized that is not affected by the amorphous layer remaining at the lower end of the thin film due to the characteristics of the excimer laser annealing. In this way, ferroelectric devices having better dielectric properties than thin films by high temperature sintering can be manufactured.

Description

METHODS FOR FORMATION FERROELECTRICS TH FILM AND METHOD FOR MANUFACTURING DEVICE OF PLANAR STRUCTURE}

The present invention relates to a method of forming a ferroelectric thin film and a method of manufacturing a planar structure device, and more particularly, to a method of forming a ferroelectric thin film capable of forming (manufacturing) a ferroelectric thin film at a low temperature of less than 300 ℃ on the substrate, and It relates to a method for manufacturing a planar structure element used.

In general, ferroelectric materials (ferroelectrics) may be used in high frequency integrated circuits or memory devices. Ferroelectrics are thinned on the substrate, for example capacitors, resonators, phase shifters, frequency filters, voltage dividers, voltage oscillators, electrical controls Various high frequency integrated circuits such as an electrical steerable antenna or a memory element for reading and writing information can be used.

However, although the ferroelectric thin film is highly applicable to various devices as described above, its use is very limited.

In general, a ferroelectric thin film is formed on a substrate by a film formation method such as a physical vapor deposition method, a chemical vapor deposition method, and a solution method using a material (metal compound) capable of exhibiting ferroelectricity after crystallization. Among them, the solution method does not require an expensive device, and can form a ferroelectric thin film inexpensively and simply. In addition, the solution method has an advantage that it is easy to precisely control the composition and can suppress the characteristic variation due to the difference in composition, and is considered as one of the very useful methods of forming the ferroelectric thin film (manufacturing method). In forming (manufacturing) a ferroelectric thin film by the solution method, a solution obtained by homogeneously dissolving a ferroelectric material (metal compound precursor) as a raw material is applied to a substrate, and the coating film is dried, and then prebaked if necessary. Then, after drying (or preliminary firing), crystallization is carried out by annealing at high temperature in the air (firing process). At this time, a crystallization process (firing process) is essential.

Ferroelectric materials must be crystallized to exhibit ferroelectric inherent properties. That is, in the non-crystallized amorphous state, it has low ferroelectricity and high dielectric loss value. Ferroelectric materials crystallize at high temperatures similar to common oxides. Therefore, crystallization is not performed when the deposition or heat treatment is not performed at a high temperature, and it is difficult to show ferroelectric characteristics.

In general, in crystallizing a ferroelectric thin film, conventionally, after coating a ferroelectric material on a substrate, using an electric furnace (furnace annealing, FA) or rapid thermal annealing at a temperature of 600 ℃ or more (mainly 700 ℃) Crystallization through high temperature heat treatment using RTA).

However, such high temperature heat treatment of 600 ° C. or higher limits the application of the ferroelectric thin film to various devices. The same is true for high temperature deposition. First, the use of the substrate is limited, so it is difficult to use a substrate that cannot withstand high temperatures. For example, a thermally weak polymer film is difficult to use as a substrate. In addition, simultaneous firing with the element is impossible. For example, when the ferroelectric material is coated on a device in which logic circuits and the like are highly integrated and then subjected to high temperature heat treatment, defects and deterioration of the device may occur. This makes it impossible to co-fire with the device, making it difficult to apply to a highly integrated composite device, for example, a device having a planar structure.

Low temperature heat treatment techniques have been proposed to solve this problem. For example, M. Lourdes Calzada et. Al. "Low-temperature Processing of Ferroelectric Thin Films Compatible with silicon Integrated Circuit Technology", Adv. Mater, 16, No. 18, pp. 1620 (2004). In order to apply to the circuit technology, a technique of lowering the firing temperature of the ferroelectric thin film to 450 ° C by using a UV-assisted RTA process was proposed. In addition, the Republic of Korea Patent Publication No. 2006-0012573 proposed a technique capable of baking at a temperature of 550 ℃, preferably below 450 ℃ by improving the composition for forming the ferroelectric thin film.

However, the above methods also crystallize the ferroelectric thin film at a limited temperature of 450 ° C., which makes it difficult to apply the ferroelectric thin film to various devices.

Accordingly, the present invention provides a method of forming a ferroelectric thin film capable of crystallizing a ferroelectric thin film at a low temperature of less than 300 ℃ using an excimer laser annealing method, and a method of manufacturing a planar structure element using the same. The purpose is.

In addition, the present invention, by optimizing the irradiation conditions of the excimer laser, a planar structure element for minimizing the adverse effect on the ferroelectric property of the amorphous layer remaining at the lower end due to the characteristics of the method of forming a ferroelectric thin film having excellent dielectric properties, and the excimer laser annealing method It is an object to provide a manufacturing method.

The present invention to achieve the above object,

(Iii) forming an amorphous preliminary ferroelectric thin film on the substrate; And

(Ii) crystallizing the amorphous pre-ferroelectric thin film by applying an excimer laser,

In the step (iii), an amorphous pre-ferroelectric thin film is formed to a thickness of 50 nm or more,

In the step (ii), an energy density of 50 mJ / cm 2 to 200 mJ / cm 2 and a method of forming a ferroelectric thin film for irradiating an excimer laser at 1 to 2,000 irradiation times are provided.

Further, according to the present invention,

(I) forming a ferroelectric thin film on the substrate; And

(II) forming an electrode on the ferroelectric thin film,

Step (I) provides a method of manufacturing a planar structure element for forming a ferroelectric thin film by the above method.

According to the present invention, the ferroelectric thin film can be formed (manufactured) under low temperature conditions of 300 ° C or lower. Accordingly, the present invention is not limited to the type of substrate, and for example, a polymer film or the like which is weak to heat can be used as the substrate, and the ferroelectric thin film can be crystallized on a device in which logic circuits and the like are highly integrated. Has

In addition, according to the present invention, it is possible to form a ferroelectric thin film having an excellent dielectric characteristic equivalent to or higher than that of the conventional high temperature heat treatment method, and the planar structure element using the same has excellent electric / electronic characteristics.

1 is a manufacturing process chart of a ferroelectric thin film according to the present invention.
2 is a manufacturing process chart according to another embodiment of the ferroelectric thin film according to the present invention.
3 is a cross-sectional view of the planar structural element according to the present invention.
4 is a plan view illustrating the electrode shape of the planar structure element according to the present invention.
5 is a surface photograph of a ferroelectric thin film crystallized by excimer laser annealing.
6 is an XRD pattern of a ferroelectric thin film crystallized by excimer laser annealing.
7 is a graph showing dielectric properties of planar structure devices.
FIG. 8 is a graph illustrating a capacity tunability characteristic of a planar structure device.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, referring to Figures 1 and 2, the method of forming the ferroelectric thin film 20 according to the present invention,

(Iii) forming an amorphous preliminary ferroelectric thin film 22 on the substrate 10;

(Ii) crystallizing the amorphous preliminary ferroelectric thin film 22.

At this time, according to the present invention, in step (iii), the amorphous preferroelectric thin film 22 is formed to have a thickness of 50 nm or more, and in step (ii), crystallization is performed by irradiating an excimer laser (Le, Excimer Laser). The crystal is irradiated with an excimer laser (Le) at an energy density of 50 mJ / cm 2 to 200 mJ / cm 2, and at 1 to 2,000 irradiation times.

According to the present invention, it is possible to form (manufacture) the crystallized ferroelectric thin film 20 at a low temperature condition of 300 ° C. or lower by crystallizing the energy of the excimer laser Le without using high temperature sintering as in the prior art. In addition, the process conditions, that is, the irradiation conditions of the excimer laser (Le) and the thickness of the thin film 22 serve as important factors for achieving the object of the present invention.

First, in the thickness of the amorphous preliminary ferroelectric thin film 22, when the thickness of the thin film 22 is less than 50 nm, the energy of the excimer laser Le may act strongly, resulting in damage to the substrate 10. That is, the energy of the excimer laser Le may be applied too strongly to the substrate 10 beyond the interface between the thin film 22 and the substrate 10, resulting in deformation of the substrate 10. Accordingly, the thickness of the thin film 22 may be 50 nm or more, and its maximum value is not limited. According to an exemplary embodiment, the maximum thickness of the thin film 22 may be 1,000 nm, but is not limited thereto. The thickness of the thin film 22 is included in the present invention as long as it is 50 nm or more.

In the energy density of the excimer laser Le, when the energy density is less than 50 mJ / cm 2, it is difficult to achieve good crystallinity and the ferroelectricity is inferior. In addition, when the energy density exceeds 200 mJ / cm 2, laser ablation may occur on the surface of the thin film 22 at the laser irradiation point. As a result, the surface of the crystallized thin film 20 is amorphous, and the ferroelectricity may be lowered.

In addition, in the irradiation frequency of the excimer laser (Le), when the irradiation frequency is 2,000 times (times), cracks may occur on the surface of the thin film 22 at the laser irradiation point. As a result, the ferroelectricity of the crystallized thin film 20 may be lowered. Accordingly, the excimer laser Le is irradiated at one to 2,000 irradiation times.

Therefore, the energy density of the excimer laser (Le), the frequency range of the irradiated laser, and the thickness of the thin film 22 prevent the damage of the substrate 10 and give ferroelectricity due to good crystallization, without applying high temperature heat. That is, it acts as an important factor that can form (crystallize) the ferroelectric thin film 20 under low temperature conditions of 300 ° C or lower. The energy density of the excimer laser (Le) is preferably 80 mJ / cm 2 to 150 mJ / cm 2, and the number of irradiation of the excimer laser (Le) is preferably 50 to 500 times. At this time, when the energy density of the excimer laser (Le) is 80 mJ / cm 2 to 150 mJ / cm 2 as above, the grain growth is improved and crystallized by conventional high temperature heat treatment (for example, 700 ° C.). It has better ferroelectricity than that.

The substrate 10 may include a semiconductor substrate, a ceramic substrate, a metal substrate, a polymer substrate, or a combination of two or more selected from these, and may be multiple layers thereof. In the present invention, the substrate 10 is not limited. The substrate 10 is a low temperature process is applied during the crystallization of the thin film 20 is not limited to the heat distortion temperature. That is, the board | substrate 10 can use what cannot endure high temperature. Substrate 10 is, for example, a polymer substrate (film), made from one or more resins selected from polyethylene terephthalate (PET), polycarbonate (PC), polyethylene naphthalate (PEN), polyether sulfone (PES), and the like. Film can be used. The substrate 10 may be flexible.

In the step (iii), the amorphous pre-ferroelectric thin film 22 is not limited as long as it can become a ferroelectric when crystallized. That is, in the present invention, the 'preliminary ferroelectric' is a material (precursor) capable of becoming a ferroelectric after crystallization, which may be selected from metal oxides including metals. Specifically, the amorphous pre-ferroelectric thin film 22 may include at least one element selected from Ba, Sr, Pb, Ca, La, K, Na, Ti, Zr, Nb, Ta, and Fe. In this case, the amorphous pre-ferroelectric thin film 22 is formed by depositing a metal oxide containing the metal element on the substrate 10 (deposition), or by coating and drying a liquid composition containing a metal oxide and a solvent. (Solution method). The amorphous pre-ferroelectric thin film 22 may be, for example, physical vapor deposition by sputtering, chemical vapor deposition, chemical solution deposition, aerosol deposition, and the like. It may be formed by various methods such as a chemical solution coating method, the method of forming the thin film 22 is not limited.

In addition, the process temperature of the step (iii) is 300 ℃ or less. For example, when formed by vapor deposition (sputtering or the like), the amorphous preliminary ferroelectric thin film 22 is formed by maintaining the temperature conditions in the chamber at 300 ° C. or lower, specifically from room temperature to 300 ° C. In addition, in the case of forming by a liquid phase method (coating, etc.), after coating a liquid composition containing a metal oxide and a solvent, and dried under conditions of 300 ℃ or less, specifically room temperature to 300 ℃ conditions of the amorphous pre-ferroelectric thin film (22 ). In this case, in the case of a liquid phase method (coating, etc.), presintering may be performed after drying, and the presintering is performed at a temperature condition of 300 ° C or lower, for example, a temperature of 100 to 300 ° C.

The amorphous pre-ferroelectric thin film 22 is crystallized by the excimer laser (Le) irradiation. The excimer laser Le is irradiated from the upper portion of the amorphous preliminary ferroelectric thin film 22 as shown in FIG. 1. Irradiation of the excimer laser Le proceeds at a temperature of 300 ° C. or less. That is, the process conditions of step (ii) is a temperature condition of 300 ℃ or less (specifically, room temperature to 300 ℃).

Therefore, in the present invention, all the process conditions when forming (manufacturing) the ferroelectric thin film 20 is 300 ℃ or less. That is, the formation step (sputter deposition or solution coating) of the preliminary ferroelectric thin film 20 and the crystallization step (excimer laser irradiation) of the thin film 20 proceed at a temperature of 300 ° C. or less. Accordingly, it is possible to use the substrate 10 that cannot withstand high temperatures, and there is no limitation on the type of the substrate 10. In addition, simultaneous firing (crystallization) with the element is possible. In other words, the ferroelectric thin film can be crystallized on a highly integrated device such as a logic circuit.

The crystallized ferroelectric thin film 20 is not limited as long as it has a ferroelectric composition, and may have a perovskite structure. The crystallized ferroelectric thin film 20 preferably has a perovskite structure, and preferably includes a composition represented by the following Chemical Formula 1.

[Formula 1]

ABO ₃

In Formula 1, A is at least one selected from Ba, Sr, Pb, Ca, La, K, and Na, and B is at least one selected from Ti, Zr, Nb, Ta, and Fe. For example, A can be Ba, Sr, Pb or a combination of Ba and Sr. And B may be Ti, Zr or a combination of Ti and Zr. More preferably, the crystallized ferroelectric thin film 20 may include at least one composition selected from Chemical Formulas 2 and 3 below. Specifically, the crystallized ferroelectric thin film 20 may include a BST-based composition of Formula 2 or a PZT-based composition of Formula 3 below. And mixtures thereof.

(2)

Ba _{1 - x} Sr _x TiO ₃

(3)

PbZr _{1 - x} Ti _x O ₃

In Chemical Formulas 2 and 3 above, the atomic fraction x is 0 ≦ x ≦ 1. Preferably, x is 0.1 ≦ x ≦ 0.9. Ferroelectric oxides including the compositions of Formulas 2 and 3 may be usefully applied to the present invention because of excellent wireline properties.

Further, according to a preferred embodiment of the present invention, the excimer laser (Le) in the step (ii) using a beam homogenizer, as described above on the amorphous pre-ferroelectric thin film 22 Irradiate the laser beam with energy density and frequency, but it is better to irradiate in the form of a square. Specifically, as shown in FIG. 2, it is preferable to irradiate the laser beam so that it is widely distributed in a rectangular shape. In this case, the energy of the laser beam is evenly distributed to achieve homogeneous crystallinity. 2, when the irradiation area of the laser Le is smaller than the area of the thin film 22, the substrate 10 may be irradiated while moving in the direction of the arrow shown in FIG. 2.

In addition, when irradiating the excimer laser (Le), the excimer gas (excimer gas) is preferably two or more different from each other selected from F, Ar, Cl, Br, Kr and Xe. For example, it is preferable to irradiate an excimer laser of ArF, KrF, XeCl, XeBr or XeF. At this time, these gases decay into an unstable state by a beam, and oscillate energy with high power to grow crystal grains of the ferroelectric thin film 20.

In addition, according to a preferred embodiment, when irradiating the excimer laser (Le), it is good to apply a temperature of 300 ℃ or less to the substrate 10. At this time, the temperature applied to the substrate 10 may be, for example, 100 ~ 300 ℃, it is preferable to apply the temperature to the lower end of the substrate 10. As described above, when the excimer laser Le is irradiated and the temperature is applied to the substrate 10, the crystallinity of the ferroelectric thin film 20 can be improved.

The ferroelectric thin film 20 formed (manufactured) according to the present invention may be applied as a ferroelectric layer such as a device of planar structure.

The ferroelectric thin film 20 formed (manufactured) according to the present invention may have some thin amorphous layers remaining at the bottom of the thin film 20 due to the characteristics of the excimer laser annealing method, wherein a planar structure is present. The device is not affected by the amorphous layer of the lower end is useful in the present invention, it is possible to manufacture a device that can maximize the characteristics of the ferroelectric layer.

On the other hand, the method of manufacturing a planar structure element according to the present invention is applied to the process of forming the ferroelectric thin film 20 of the present invention as described above. Hereinafter, a method of manufacturing a planar structure element according to the present invention will be described with reference to FIGS. 3 and 4.

Method for producing a planar structure element according to the present invention,

(I) forming the ferroelectric thin film 20 on the substrate 10,

(II) forming an electrode 30 on the ferroelectric thin film 20.

At this time, the step (I) is formed by the method of forming the ferroelectric thin film 20 according to the present invention as described above. Step (I) is as described above, so a detailed description thereof will be omitted.

In the step (II), the electrode 30 may be conductive. The electrode 30 may be formed by depositing (eg, sputtering) an electrode material, for example, an electrode material including a metal or a metal oxide. Metal is not particularly limited as the electrode material, but at least one selected from copper (Cu), silver (Ag), aluminum (Al), and the like may be exemplified. The metal oxide may be, for example, one or more selected from indium oxide, tin oxide, zinc oxide, and the like, but is not limited thereto. Electrode 30 includes those commonly used in the art, and is not limited so long as it has conductivity.

Although the planar structure element is not particularly limited in the present invention, the ferroelectric thin film 20 and one or more electrodes 30 may be included, and all the electrodes 30 may have a structure positioned on the ferroelectric thin film 20. .

In step (II), that is, the formation process of the electrode 30 includes a step of patterning the electrode 30. In detail, the step (II) may include a process of depositing the electrode 30 on the ferroelectric thin film 20 and a process of patterning the deposited electrode 30. In this case, various methods may be considered for the patterning of the electrode 30, and for example, an etching method or a masking method may be used. In addition, the electrode 20 may be formed on the ferroelectric thin film 20, but the space 50 may be formed between the electrodes 20 as illustrated in FIG. 3, but the ferroelectric layer without the lower electrode may be used. If it is an element, the shape of the electrode 30 is not limited. For example, as illustrated in FIG. 4, the electrode 30 may include a ring type 31, a co-planar type 32, an inter digital transducer type, 33) and strip line type 34, but may be patterned in a variety of shapes, such as, but not limited to.

According to the present invention, the process of forming the ferroelectric thin film 20 may be performed at a low temperature of 300 ° C. or less, and the manufacturing process of the planar structure element including the same may also be performed at a low temperature of 300 ° C. or less. The ferroelectric thin film 20 and the planar structure element formed (manufactured) according to the present invention can be applied to various fields, for example, a highly integrated element or a memory element, without being limited. For example, in the case of a planar structure element, a capacitor, a resonator, a phase shifter, a frequency filter, a voltage divider, a voltage according to a patterning structure of the electrode 30 It can be used in various devices such as a voltage oscillator and an electrical steerable antenna.

According to the present invention described above, as described above, the ferroelectric thin film 20 can be formed under a low temperature condition of 300 ° C or lower. Accordingly, the ferroelectric thin film 20 can be crystallized on a device in which a polymer film or the like, which is weak to heat, can be used, and a logic circuit or the like can be crystallized. It is possible to apply. In addition, according to the present invention, compared to the conventional high temperature heat treatment method, it is possible to form (crystallization) of the ferroelectric thin film 20 having an excellent dielectric characteristic equivalent or more, the planar structure device using the same is excellent Has electronic properties.

Hereinafter, embodiments of the present invention will be exemplified. The following examples are provided to aid understanding of the present invention, and thus the technical scope of the present invention is not limited thereto.

[Example 1 and Comparative Example 1]

Barium carbonate, strontium oxide and titanium oxide were used as preliminary ferroelectric materials (precursors). The preliminary ferroelectric material (precursor) was coated on the substrate to a thickness of 300 nm by using a sol-gel method, and then a solvent and an organic material were removed by heating at 300 ° C. to form an amorphous thin film. Thereafter, an excimer laser was irradiated 200 times to the surface of the amorphous thin film to form a crystallized BST thin film having a Ba _{1 - x} Sr _x TiO ₃ (x = 0.4) composition. At this time, as shown in Table 1, the energy density (mJ / ㎠) of the excimer laser and the number of irradiation times of the excimer laser were crystallized according to each Example and Comparative Example. Subsequently, the substrate state and the surface of the thin film were observed with respect to the thin film specimens crystallized according to the Examples and Comparative Examples, and the results are shown together in the following [Table 1]. In addition, by measuring the dielectric constant (Dielectric constant) for each thin film specimen, the results are shown in Table 1 below. At this time, the dielectric constant (Dielectric constant) is expressed as a relative value based on the value (100) of Example 1-3 (energy density 90 mJ / ㎠, irradiation frequency 200 times).

<Characteristic evaluation results according to the energy density and frequency of irradiation
Remarks Comparative Example
1-1 Example Comparative Example
1-2 1-1 1-2 1-3 1-4 1-5 1-6 Thin film thickness
(Nm) 300 300 300 300 300 300 300 300 Energy density
(mJ / cm 2) 210 150 100 90 80 70 50 40 Survey Count
One One 200 200 250 300 500 2100 Board Status
transform Good Good Good Good Good Good Good Thin film surface
Explosion Good Good Good Good Good Good crack Genetic characteristics
- 5 102 100 98 95 56 10

As shown in [Table 1], when the energy density exceeds 200 mJ / cm 2, deformation of the substrate and fusion of the surface of the thin film occurred, and when the energy density was less than 50 mJ / cm 2, due to non-crystallization It was found that the characteristics were significantly reduced. In addition, when the number of irradiation times was low, dielectric properties due to non-crystallization decreased, and when the number of irradiation times exceeded 2,000, cracks were observed on the surface of the thin film.

[Example 2]

In order to examine the microstructure and crystallinity of the thin film, a pre-ferroelectric material (precursor) was coated on a Pt / Ti / SiO ₂ / Si substrate using a sol-gel method, followed by heat at 150 ° C. Was added to remove the solvent and organics to form an amorphous thin film of 300 nm thickness. Thereafter, an excimer laser was irradiated 200 times on the surface of the amorphous thin film to form a crystallized BST thin film having a Ba _{1 - x} Sr _x TiO ₃ (x = 0.45) composition. In this case, the energy of the excimer laser was variously applied to 80 mJ / cm 2, 90 mJ / cm 2, 100 mJ / cm 2, and 110 mJ / cm 2.

5 is a surface photograph of a crystalline thin film according to an energy density of an excimer laser. In the photograph of FIG. 5, reference numeral 06 is 80 mJ / cm 2, 07 is 90 mJ / cm 2, 08 is 100 mJ / cm 2, and 09 is 110 mJ / cm 2. As shown in FIG. 5, it can be seen that the grain size of the ferroelectric thin film grows as the energy density of the laser irradiated on the thin film increases. Since ferroelectricity is due to the grain size of the ferroelectric, grain growth of the ferroelectric thin film is considered to be largely due to the improvement of the ferroelectricity of the highly integrated device.

6 is an XRD pattern of the crystallized ferroelectric thin film. In this case, in the XRD pattern of FIG. 6, reference numeral 10 is 80 mJ / cm 2, 11 is 90 mJ / cm 2, 12 is 100 mJ / cm 2, and 13 is 110 mJ / cm 2. As shown in FIG. 6, it can be seen that the amorphous thin film was crystallized by the excimer laser irradiation, and a ferroelectric thin film including the Ba _{1 - x} Sr _x TiO ₃ material having a Perovskite structure was formed.

Example 3 and Comparative Example 2

In order to fabricate a planar structure device, a ferroelectric thin film was formed on an aluminum oxide substrate. The ferroelectric thin film was formed to a thickness of 300 nm in the same manner as in Example 2, the energy of the excimer laser is irradiated 200 times, the energy density of 70 mJ / ㎠, 80 mJ / ㎠, 90 mJ / ㎠, and 100 mJ / Various applications were made in cm 2. And crystallized Ba _{1 - x} Sr _x TiO ₃ A copper (Cu) electrode was deposited on the surface of the thin film at room temperature using a sputtering method, and then patterned by an etching process. Thereafter, an electrically variable capacitor device was manufactured by a conventional method.

In addition, in order to compare with the conventional crystallization method, in the same manner as described above, in crystallizing the ferroelectric thin film, crystallization was carried out at high temperature sintering at 700 ° C. without irradiating an excimer laser (Comparative Example 2).

For each device specimen prepared as above, the dielectric properties were evaluated, and the results are shown graphically in FIG. 7. In Fig. 7, reference numeral 17 is 70 mJ / cm 2, 18 is 80 mJ / cm 2, 19 is 90 mJ / cm 2, and 20 is a result of dielectric properties applied at an energy density of 100 mJ / cm 2. 7 to 21 are conventional methods (Comparative Example 2), which are results of dielectric properties of specimens sintered at 700 ° C. at high temperature.

As shown in FIG. 7, as the energy of the irradiated excimer laser increases, dielectric properties of the ferroelectric also increase. In addition, when irradiated with energy of 80 mJ / ㎠ (18) shows the dielectric properties equivalent to the conventional high temperature sintering (21), especially when the energy of 90 mJ / ㎠ (19) and 100 mJ / ㎠ (20), It can be seen that it has higher dielectric properties than the conventional high temperature sintering 21.

FIG. 8 is a graph evaluating capacity tunability for each device specimen prepared above. In Fig. 8, reference numeral 22 denotes 70 mJ / cm 2, 23 denotes 80 mJ / cm 2, 24 denotes 90 mJ / cm 2, and 25 denotes a variable variable capacity evaluation result applied at an energy density of 100 mJ / cm 2. 8 to 26 are conventional methods (Comparative Example 2), which are results of specimens sintered at high temperature at 700 ° C.

As shown in Figure 8, it can be seen that the capacity variable capacity increases as the irradiated energy increases. It can also be seen that at all energy densities, higher capacity variability is shown than high temperature sintering 26 at 700 ° C.

As can be seen in the above experimental example, it can be seen that a thin film having ferroelectricity can be formed at a low temperature process condition of 300 ° C. or less through a laser annealing method without using high temperature sintering. In addition, when implemented as a planar device, it can be seen that the dielectric properties are superior to those of the thin film crystallized through the conventional high temperature sintering.

10 substrate 22 amorphous pre-ferroelectric thin film
20: ferroelectric thin film 30: electrode

Claims (11)

In the method of manufacturing a ferroelectric element of a planar structure,
(Iii) forming an amorphous preliminary ferroelectric thin film on the substrate; And
(Ii) forming a ferroelectric thin film by crystallizing an upper surface of the amorphous pre-ferroelectric thin film by irradiating an excimer laser; And
(iii) forming an electrode on the ferroelectric thin film; And
(iv) patterning the electrode,
Process temperature of the step (iii) is 100 ~ 300 ℃,
In the step (ii) the temperature of the substrate is maintained at 20 ~ 300 ℃,
The energy density of the excimer laser to be irradiated is 80 mJ / ㎠ to 150 mJ / ㎠, the number of irradiation is 1000 to 2000 times,
When the electrode patterning in the step (iv), the electrode is a planar ferroelectric device manufacturing method, characterized in that the electrode is made in a planar structure on top of the ferroelectric thin film.
The method of claim 1,
The amorphous pre-ferroelectric thin film formed in step (iii) includes at least one element selected from Ba, Sr, Pb, Ca, La, K, Na, Ti, Zr, Nb, Ta, and Fe. Ferroelectric device manufacturing method.
delete The method of claim 1,
The ferroelectric thin film crystallized in the step (ii) is a ferroelectric device manufacturing method having a planar structure, characterized in that it comprises a composition represented by the following formula (1).
[Formula 1]
ABO3
(In Formula 1, A is at least one selected from Ba, Sr, Pb, Ca, La, K and Na, B is at least one selected from Ti, Zr, Nb, Ta and Fe.)
delete The method of claim 1,
The method of manufacturing a ferroelectric device having a planar structure, characterized in that to irradiate the excimer laser in the form of a square in the step (ii).
delete delete delete delete delete

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