KR101430689B1 - Scintilator structure material having nano structure and method of preparing same - Google Patents

Abstract

The present invention relates to a nanostructured scintillator and a method for producing the same. The nanostructured scintillator includes a substrate on which pores are formed and a scintillator layer formed on the substrate, the pores having an aspect ratio of 10 to 1000, It is filled with step coverage ratio.

Description

TECHNICAL FIELD [0001] The present invention relates to a nanostructured scintillator structure and a method of manufacturing the same. BACKGROUND ART [0002]

The present disclosure relates to nanostructured scintillator structures and methods of making the same.

Scintillators are substances that absorb high-energy radiation such as X-rays or gamma rays and convert them into visible light. When the radiation is absorbed into the scintillator, electrons and holes are excited in the conduction band and the valence band, and when visible light is recombined through the luminescence center formed in the bandgap, the visible light corresponding to the energy difference is emitted.

The emitted visible light is absorbed through the optical semiconductor sensor such as a photodiode connected to the scintillator, and generates electrons and holes. By converting this into an electrical signal, it provides the information such as the amount and position of the radiation to be used for radiographic imaging and treatment do.

Meanwhile, since the X-ray medical image diagnostic device utilizing the X-ray photoconversion characteristic of such a scintillator is used close to the body during its use and is frequently used, the sensitivity of the image sensor of high sensitivity And it is necessary to secure a high-resolution image for precise diagnosis.

Therefore, in order to realize a high sensitivity and a high resolution in the X-ray medical imaging field, studies on a scintillator material having a high fluorescence efficiency and a pixel structure capable of improving the resolution are progressing in the world.

Conventional scintillator manufacturing methods include a method of growing a scintillator single crystal on a photodetector substrate and a method of manufacturing a scintillator in a thick film form through a deposition process. In the case of a thick film, the prepared scintillator may be used in conjunction with a photodetector.

The method of growing the single crystal can obtain a scintillator of high quality, but it is expensive. Further, in order to increase the sensitivity, the thickness of the single crystal material must be increased. In this case, resolution is reduced due to scattering of the converted light in the crystal, which is not suitable.

In addition, the method using the deposition process can reduce the manufacturing cost and is formed as a thick film, so that the thickness is increased and the thickness is increased. However, since the thick-film scintillators have a low resolution, there is a problem in that, in order to increase the resolution, the scintillators are grown in a column shape with a diameter of several microns and a length of 100 microns or more in the direction perpendicular to the substrate, Is processed so as to have a depth of 100 microns or more and a scintillator is deposited on the pores by a precipitation method or the like to form a thick film structure in the form of a pixel. However, these methods have a problem in that the scintillator pillars are inclined or bubbles are generated and impurities are mixed in the solution. As a result, there is no way to simultaneously improve sensitivity and resolution.

One embodiment of the present invention is to provide a nanostructured scintillator structure having excellent spatial resolution for radiation detection.

Another embodiment of the present invention provides a method of manufacturing the scintillator structure.

One embodiment of the present invention is directed to a semiconductor device comprising: a substrate having pores formed therein; And a scintillator layer formed on the substrate, wherein the pores have an aspect ratio of 10 to 1000, and the pores are filled with a step coverage of 80% or more of scintillation material.

The thickness of the scintillator layer may be 10 nm to 100 nm.

The pores may have a diameter of 100 nm to 10 μm and a depth of 100 μm to 400 μm.

The scintillator may be HfO ₃ : Ce, (Y, Gd) ₂ O ₃ : Eu, Pr, Gd ₂ O ₂ S: Pr, Ce, F, Gd ₃ Ga ₅ O ₁₂ : Cr, Ce, .

Another embodiment of the present invention provides a method for forming a plurality of pores in a substrate; And depositing a scintillator by atomic layer deposition (ALD) on the substrate having the pores formed therein. The present invention also provides a method of manufacturing a nanostructured scintillator structure.

The atomic layer deposition method comprising the steps of: 1) adsorbing a scintillator precursor on the substrate under a dilution gas; Removing by-products from the substrate under a diluent gas; A third step of converting the scintillation precursor into a scintillant by causing an oxidation reaction on the substrate from which the byproduct has been removed; And removing the byproduct from the oxidized substrate under the diluent gas.

In the manufacturing method according to an embodiment of the present invention, the dopant precursor may further be used in the first step.

In addition, in the above-mentioned manufacturing method, a step of adsorbing the dopant precursor on the substrate may be further performed before and after the first step and the second step.

The nanostructured scintillator structure according to an embodiment of the present invention can further improve the structure of the existing pixel shape to exhibit a resolution corresponding to the size of the nanopores and can utilize the scintillator thickness corresponding to the pore depth for light calculation It is possible to reduce the deposition thickness required for radiation absorption, thereby reducing the manufacturing cost of the scintillator.

In addition, the method of fabricating a nanostructured scintillator structure according to an embodiment of the present invention can form a dense and uniform scintillation complex structure on a substrate by using an atomic layer deposition process, thereby suppressing light scattering, It is possible to reduce the thickness of the scintillator deposition necessary for the radiation absorption by the corresponding thickness, and to improve the spatial resolution and cost efficiency for X-ray radiation detection.

1 is a SEM photograph of a section of a scintillator structure manufactured according to Comparative Example 1. Fig.
2 is a SEM photograph of a scintillator structure manufactured according to Example 1. Fig.
3 is a view showing the conditions of the atomic layer deposition process performed in Example 1. Fig.
4A and 4B are SEM photographs of a scintillator structure manufactured according to Example 2. Fig.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

One embodiment of the present invention includes a substrate having a pore formed therein and a scintillator layer formed on the substrate, wherein the pore has an aspect ratio (depth / diameter) of 10 to 1000 and the pore has a step coverage rate of 80% Lt; RTI ID = 0.0 > nanostructured scintillator < / RTI > structure.

As described above, the scintillator is filled with pores having an aspect ratio of 10 to 1000 at a coverage rate of 80% or more, preferably 80% or more and 100% or less. Thus, the scintillator structure according to an embodiment of the present invention includes a dense and uniform scintillator So that it is possible to suppress the light scattering and reduce the thickness of the scintillator necessary for radiation absorption by a thickness corresponding to the depth of the pores. Thus improving spatial resolution and cost-effectiveness for X-ray activity detection.

That is, the thickness of the scintillator layer according to an embodiment of the present invention may be 100 nm or less, more specifically, 10 nm to 100 nm. In one embodiment of the present invention, since the scintillator layer can be formed thinner than conventionally about 10 탆 to 100 탆, the use of the scintillator can be reduced, which is economical.

The pores may have a diameter of 100 nm to 10 μm and a depth of 100 μm to 400 μm.

The scintillator may be HfO ₃ : Ce, (Y, Gd) ₂ O ₃ : Eu, Pr, Gd ₂ O ₂ S: Pr, Ce, F, Gd ₃ Ga ₅ O ₁₂ : Cr, Ce, .

The nanostructured scintillator according to the present invention can improve the sensitivity and resolution of a radiation detector such as an X-ray or a gamma ray or a radiation image sensor. Therefore, the nanostructured scintillator according to the present invention can be used variously as a medical image diagnostic device or an industrial image measuring device have. In particular, a dental scintillator that is closely used to a human body can be used more effectively because it has to be minimized in harmfulness at a low dose.

Another embodiment of the present invention is a method for forming a plurality of pores in a substrate, And depositing a scintillator on the substrate having the pores formed thereon by an atomic layer deposition method. The present invention also provides a method of manufacturing a nanostructured scintillator structure. Hereinafter, each step will be described in detail.

The pores may be nano pores having a diameter of several tens to several hundreds of nanometers, specifically, 100 nm to 10 탆. The nano pores may have a depth of 100 mu m or more, specifically 100 mu m to 400 mu m.

The nanopores may have a diameter and depth in the above range and an aspect ratio (depth / diameter) of 100 to 1000.

The substrate may be a metal, a semiconductor, or a plastic. The metal may be Al or Mg, and the semiconductor may be Si, Ge or C, and the plastic may be polyimide or polyurethane.

The nano pore forming process may be an electrochemical etching method or an anodizing method, and any process may be used as long as it can form nano pores. Of these, the anodic oxidation method is simple and widely practiced, and therefore, the anodic oxidation method will be described below. Of course, in the case where nano pores are formed by an electrochemical etching method, the process is well known in the art, and therefore, even if specific conditions are not described in this specification, those skilled in the art can use nano- It is of course possible to form pores.

The anodic oxidation method is an example in which the substrate is anodized in an electrolyte, and the case where Al is used as the substrate will be described below as an example. However, this is merely an example, and since Al as well as Si can be used as a substrate, it is apparent that the substrate is not limited to Al in one embodiment of the present invention.

When positive (+) is applied to an aluminum substrate and negative (-) is applied to a counter electrode, ions of aluminum with positive ions are eluted as a solution, and oxygen ions and hydroxide ions in the solution move to the aluminum substrate surface, Al ₂ O ₃ ). On the other hand, the acid solution (electrolytic solution) partially dissolves in the oxide film forming the contact surface, so that the surface of the oxide film becomes rough, the electric field concentrates on the thinnest side, and the concentrated electric field promotes dissolution of oxide film, Due to the phosphorus oxidation reaction, pores are formed and the initial pores are further grown during the anodic oxidation to form long porous channels.

The electrolytic solution may be water, sulfuric acid, oxalic acid, or a combination thereof, and may be in the form of an aqueous solution thereof.

In an embodiment of the present invention, the size and spacing of the pores formed in the substrate can be controlled by adjusting the voltage of the anodizing process and the composition of the electrolyte.

The voltage of the anodizing process is suitably from 15V to 20V, and the anodizing time is from 30 minutes to 60 minutes.

In addition, the anodic oxidation process can be carried out at 0 캜 to 60 캜.

The concentration of the electrolytic solution may be 10 wt% to 30 wt%.

When an anodizing process is performed under the conditions of voltage, time, temperature and electrolyte concentration, pores having a desired size, that is, a diameter of 100 nm to 10 μm and a depth of 100 μm to 400 μm may be formed on the substrate have.

Subsequently, a scintillator is deposited on the substrate having the nanopores formed thereon by an atomic layer deposition method using a scintillator precursor.

The atomic layer deposition method comprising the steps of: 1) adsorbing a scintillator precursor on the substrate under a dilution gas; Removing by-products from the substrate under a diluent gas; A third step of converting the scintillation precursor into a scintillant by causing an oxidation reaction on the substrate from which the byproduct has been removed; And removing the byproduct from the oxidized substrate under the diluent gas.

The diluent gas may be Ar or N ₂ . Further, hydrogen gas (H ₂ ) can be further used together with the diluent gas. When the diluent gas and the hydrogen gas are used together, the mixing ratio thereof may be 50: 50% by volume to 80: 20% by volume.

The scintillator precursor is a precursor for radiation absorption, and includes compounds including Hf, Gd, Ga, Ba and the like. Specific examples of the scintillator precursor is tetrakis (ethylmethylamino) hafnium (TEMAH: Hf [N (CH 3) (C 2 H 5)] 4), teurimetilga stone Solarium (Trimethylgadolinium), trimethyl gallium (Trimethylgallium), bis (ethyl Bis (ethylcyclopentadienyl) barium), and the like.

In the manufacturing method according to an embodiment of the present invention, the dopant precursor may further be used in the first step. In addition, in the above-mentioned manufacturing method, a step of adsorbing the dopant precursor on the substrate may be further performed before and after the first step and the second step.

The dopant precursor is for photo-conversion, and includes compounds containing Ce, Eu or Cr. Specific examples of the dopant precursor and the like _{Ce [N (CH 3) (} C 2 H 5) 4], Eu [N (CH 3) (C 2 H 5) 4], or chromium hexacarbonyl (Chromium hexacarbonyl) .

The scintillator deposited according to the process may be HfO ₃ : Ce, Gd ₂ O ₃ : Eu, Pr, Gd ₂ O ₂ S: Ce, Gd ₃ Ga ₅ O ₁₂ : Cr, Ce or a combination thereof.

The addition amount of the dopant precursor can be controlled by controlling the number of deposition cycles of the scintillator precursor and the number of deposition cycles of the dopant precursor, and it is suitable to use the scintillator precursor and the dopant precursor in a ratio of 50:50 to 90:10 weight% .

The first step may be performed for 1 second to 5 seconds, the second step may be performed for 10 seconds to 20 seconds, the third step may be performed for 2 seconds to 10 seconds, and the fourth step may be performed for 10 seconds to 20 seconds can do. The reaction can be carried out at a temperature of 100 to 300 캜.

In the third step, the oxidation reaction may be performed by forming a plasma by applying a gas such as oxygen, H ₂ O, or O 3.

The above steps 1 to 4 are repeated for one cycle, and the cycle is repeated according to the deposition thickness and the deposition rate to deposit the atomic layer to a thickness of 10 nm to 100 nm. The deposition rate may be about 0.1 nm to 0.2 nm per cycle.

If the scintillator layer is to be made thicker in order to further improve the sensitivity of the converted light to improve the sensitivity, the above-described atomic layer deposition method is carried out up to 100 nm, and thereafter, the conventional chemical vapor deposition method, sputtering method, May be increased.

As described above, the nanostructured scintillator structure according to one embodiment of the present invention uses an atomic layer deposition method, so that the content of impurities is low, defects such as pinholes can be minimized, Especially, it is possible to deposit precisely. In addition, the scintillator can be filled with pores with high aspect ratios of 10 to 1000 at a coating rate of 80% or more. Therefore, it is possible to suppress the light scattering and reduce the thickness of the scar deposition required for radiation absorption, thereby improving spatial resolution and cost efficiency for radiation detection.

Hereinafter, examples and comparative examples of the present invention will be described. The following embodiments are only examples of the present invention, and the present invention is not limited to the following embodiments.

(Comparative Example 1)

Pores were formed on the Si wafer by electrochemical etching to a pore size (diameter) of about 4 탆 to 7 탆 and a depth of about 400 탆. The aspect ratio of this pore was about 100.

In the electrochemical etching method, an etching solution in which dimethylformamide (DMF) and a 49% HF aqueous solution were mixed at a ratio of 80:20 volume% while applying a voltage so that a current density of 2 mA cm was kept constant on a Si wafer at room temperature , The Si wafer was etched to form pores, and then the etching was performed while increasing the current density to 15 mA cm to increase the size and depth of the pores.

The CsI: Tl scintillator powder was heated to 621 캜 and melted and embedded in pores formed in the Si wafer to prepare a scintillator structure.

A sectional SEM photograph of the manufactured scintillator structure is shown in Fig. As shown in Fig. 1, although the scintillator is filled in the vicinity of the surface, a hollow space in which the scintillator is not filled is generated in the lower part of the trench, and light is scattered, so that shading appears (step coverage ratio: 0% when empty space is formed, 100% when no empty space is formed, and 100% when completely filled. Coverage of step coverage is 0% and 100%, and average value is about 50%). As a result, absorption and scattering of light occurs at the interface between the scintillator and the substrate, which results in a decrease in sensitivity when applied to a radiation sensor.

(Example 1)

The aluminum substrate was anodized in a 20 vol.% Aqueous sulfuric acid electrolyte to form pores.

In the anodic oxidation process, a positive electrode (+) was applied to aluminum at a temperature of 3 ± 0.5 ° C and a negative electrode (-) was applied to a counter electrode (platinum). At this time, the applied voltage was 18 V and the anodizing process was performed for 30 minutes.

The pores formed in the above process had a diameter of 40 nm as shown in Fig. Further, the pore depth was 200 mu m and the aspect ratio was about 500.

Subsequently, a scintillation material was deposited on the punched aluminum substrate by an atomic layer deposition process. The atomic layer deposition process was performed using a reactor having a scintillator precursor inlet and an oxygen gas inlet, and was performed in four steps.

In the atomic layer deposition process, the scintillator precursor and the atmospheric conditions are shown in Fig. In FIG. 2, 1.5 s, 10 s, 3 s, and 10 s of the x-axis mean the time for the first stage, second stage, third stage and fourth stage, respectively, and the TEMAH and the second Ar of the Y-axis are injected into the scintillator precursor inlet And O2 and fourth Ar represent the material to be injected into the oxygen inlet.

As shown in FIG. 3, Ar gas as a diluent gas is injected at a rate of 200 sccm (standard cubic centimeter per minute, cm 3 / min) to the scintillator precursor inlet in steps 1 to 4, Respectively. At this time, purge was performed to remove reaction gas and by-products in the scintillator injection port. O ₂ was injected into the oxygen gas inlet in the form of an oxygen plasma having a radio frequency of 100 W in step 3, and the injection rate was 200 sccm. In addition, the dilution gas, Ar gas, was injected into the oxygen gas inlet at a rate of 200 sccm in the first stage, the second stage and the fourth stage except for the third stage. At this time, in order to remove the reaction gas and the by- O ₂ - was carried out a purge (O -purge _2).

(TEMH, Hf [N (CH ₃ ) (C ₂ H) ₅ ] ₄ ), which is a Hf precursor, is introduced into the scintillator precursor inlet at a rate of 100 sccm , it was adsorbed onto the substrate in 1.5 seconds 280 ℃. in addition, a dopant _{Ce [N (CH 3) (} C 2 H 5) 4] was injected with the precursor to the scintillator.

Subsequently, the step of desorbing byproducts was carried out at 280 DEG C for 10 seconds (step 2). As shown in Fig. 3, since Ar gas is injected into the whole process, this process is also carried out in the presence of a diluting gas.

Then, as shown in Fig. 3, an oxygen plasma having a radiation frequency of 100 W was injected into the oxygen inlet at a rate of 200 sccm, and the oxidation reaction was carried out for 3 seconds (Step 3). As shown in FIG. 3, the Ar gas was continuously injected at a rate of 200 sccm through the oxygen inlet, but the Ar gas injection was stopped in the third stage of injecting the oxygen plasma.

In a fourth step, Ar gas as a diluting gas was injected again at a rate of 200 sccm to desorb the by-products.

The above steps 1 to 4 were performed as one cycle, and 300 cycles were carried out to form a scintillator thin film having a thickness of about 30 nm on the substrate. That is, a HfO ₃ : Ce scintillator was deposited on the pores, and then a scintillator thin film was formed on the substrate. The step coverage ratio of the scintillators deposited on the pores was 90% or more (as shown in FIGS. 4A and 4B, no voids were formed in the lower portion of the pores, and the scintillators were generally filled in the pores).

Pore SEM photographs of the surface portion of the scintillator structure formed according to the above method are shown in Figs. 4A and 4B (Fig. 4A: surface portion of pores, and 4b: bottom portion of pores). As shown in FIGS. 4A and 4B, it can be seen that the scintillator material is densely deposited both in the vicinity of the surface and in the vicinity of the bottom. That is, even though the aspect ratio is high, it can be seen that the scintillator material is uniformly deposited in the pores.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And it goes without saying that the invention belongs to the scope of the invention.

Claims (11)

A substrate having pores formed therein; And
And a scintillator layer formed on the substrate,
The pores have an aspect ratio of 10 to 1000,
Wherein the scintillator is filled in the pores at a step coverage ratio of 80% or more
As nanostructured scintillator constructions,
The nanostructured scintillator structure forming a plurality of pores in the substrate;
And depositing a scintillator on the substrate having the pores formed thereon by an atomic layer deposition method. The method according to claim 1,
Wherein the scintillator layer is between 10 nm and 100 nm. The method according to claim 1,
Wherein the pores have a diameter of 100 nm to 10 mu m and a depth of 100 mu m to 400 mu m. The method according to claim 1,
Wherein the scintillator is a nanostructured scintillator structure that is HfO ₃ : Ce, (Y, Gd) ₂ O ₃ : Eu, Gd ₂ O ₂ S: Ce, Gd ₃ Ga ₅ O ₁₂ : Cr, or combinations thereof. Forming a plurality of pores in the substrate;
A scintillator is deposited on the substrate having the pores formed thereon by atomic layer deposition to fill the scintillator with a step coverage ratio of 80% or more
≪ / RTI > wherein the nanostructured scintillator structure is a nanostructure. 6. The method of claim 5,
The atomic layer deposition method comprising the steps of: 1) adsorbing a scintillator precursor on the substrate under a dilution gas;
Removing by-products from the substrate on which the scintillator precursor is adsorbed under a dilution gas;
A third step of converting the scintillation precursor into a scintillant by causing an oxidation reaction on the substrate from which the byproduct has been removed; And
Four steps of desorbing by-products from the oxidized substrate under dilute gas
≪ / RTI > The method according to claim 6,
Wherein the dopant precursor is further used in step 1 above. The method according to claim 6,
Further comprising the step of adsorbing the dopant precursor to the substrate before and after the first and second steps. The method according to claim 1,
Wherein the aspect ratio is 500 to 1000. < Desc / Clms Page number 24 > 6. The method of claim 5,
The atomic layer deposition method comprises the steps of: 1) adsorbing a scintillator precursor on a substrate having the pores formed therein under a dilution gas; Removing by-products from the substrate on which the scintillator precursor is adsorbed under a dilution gas; A third step of converting the scintillation precursor into a scintillant by causing an oxidation reaction on the substrate from which the byproduct has been removed; And a fourth step of desorbing the by-product from the oxidized substrate under the diluent gas,
Further comprising the step of further using the dopant precursor in the step 1 or the step of adsorbing the putt precursor on the substrate on which the pores have been formed even after performing the step 1 and before carrying out the step 2,
Wherein the ratio of the scintillator precursor and the dopant precursor is 50:50 to 90:10% by weight. 6. The method of claim 5,
The atomic layer deposition method comprises the steps of: 1) adsorbing a scintillator precursor on a substrate having the pores formed therein under a dilution gas; Removing by-products from the substrate on which the scintillator precursor is adsorbed under a dilution gas; A third step of converting the scintillation precursor into a scintillant by causing an oxidation reaction on the substrate from which the byproduct has been removed; And a fourth step of desorbing the by-product from the oxidized substrate under the diluent gas,
Wherein said step 1, step 2, step 3, and step 4 are performed at a film formation rate of 0.1 nm to 0.2 nm per cycle.

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