KR20210136421A - Vertical Chemical Deposition Reactor - Google Patents

Abstract

The present invention relates to a vertical chemical evaporator using a liquid aerosol. According to one embodiment of the present invention, the vertical chemical evaporator includes: a gas injection part injecting carrier gas; a mist providing part including a water tank having one side connected to the gas injection part and storing a precursor solution, and equipped with a spraying vibrator for spraying the precursor solution in a liquid aerosol state to the carrier gas; a reactor connected with the other side of the mist providing part, and extended vertically such that the liquid aerosol can be transferred vertically; a substrate placed to be brought into contact with the liquid aerosol on a vertical transfer path of the liquid aerosol; and a heating part for heating the reactor and the substrate. The vertical chemical evaporator can bring about an effect of precisely controlling temperature and enabling uniform evaporation while using a liquid aerosol.

Description

Vertical Chemical Deposition Reactor

The present invention relates to a vertical chemical vapor deposition machine. More particularly, it relates to a vertical chemical vapor deposition machine configured to have the same deposition efficiency regardless of a portion of a substrate by providing a chemical vapor deposition device generally horizontally disposed in a vertical form to the ground.

CVD is a technology for depositing materials such as semiconductors on a substrate by causing a chemical reaction in a gaseous state. In general, gas is homogeneously mixed by Brownian motion at room temperature even if different gases are mixed. Therefore, most of the CVD reactors do not need to consider the layering of the gas according to the density, and even if the reactor and substrate holder are horizontal to the ground, there is no difference in the degree of deposition for each region. (Korea Registered Patent No. 10-2099216)

On the other hand, recently, a process for preparing a powder by making a precursor in the form of a liquid aerosol and drying has been proposed. (Korea US Patent No. 10-0925150)

When using the MIST deposition method to make a precursor in the form of a liquid aerosol by combining the above two inventions, and deposit it, two major problems occur.

First, liquid aerosols are liquids and, because they are heavier than air, they sink to the bottom. Therefore, when the liquid aerosol flowing horizontally is reacted to the substrate, the lower the substrate is, the higher the reaction result is because the density of the reactant is higher.

Second, since the liquid aerosol is supplied with the precursor mixed or dissolved in the solvent, all of the solvent must be evaporated before deposition. If the solvent approaches the deposition surface without evaporating all, the deposition surface is rapidly cooled and there is a problem in that the reaction does not occur smoothly.

Accordingly, it is required to develop a technology for a chemical vapor deposition machine capable of solving the above-mentioned problems.

On the other hand, the above-mentioned background art cannot necessarily be said to be a known technology disclosed to the general public prior to the filing of the present invention.

Republic of Korea Patent Registration No. 10-2099216 (2020.04.03.) Republic of Korea Patent No. 10-0925150 (2009.10.29.

The present invention provides a vertical type chemical vapor deposition machine in which deposition is uniform while using a liquid aerosol.

The present invention provides a vertical chemical vapor deposition apparatus capable of maintaining a constant deposition temperature while using a liquid aerosol.

As a technical means for achieving the above-described technical problem, the vertical chemical vapor deposition machine according to an embodiment of the present invention includes a gas injection unit for injecting a carrier gas, one side is connected to the gas injection unit, and a water tank containing a precursor solution and a mist providing part having a spray vibrator for spraying the precursor solution into the carrier gas in a liquid aerosol state, a reactor connected to the other side of the mist providing part and extending vertically so that the liquid aerosol moves vertically, the and a substrate arranged to come into contact with the liquid aerosol on a vertical movement path of the liquid aerosol and a heating unit for heating the reactor and the substrate.

The reactor may further include an auxiliary substrate for thermal insulation positioned between the substrate and the mist providing unit.

The diameter of the auxiliary substrate for thermal insulation and the separation distance between the auxiliary substrate for thermal insulation and the substrate may be determined such that the heat retention rate at a point spaced 1.5 cm from one surface of the substrate to which the liquid aerosol touches is 50% or more.

The auxiliary substrate for thermal insulation may be spaced apart from the substrate by 1.5 cm or more and 1/3 or less of the diameter of the reactor, and the diameter may be 1/12 or more and 1/2 or less of the diameter of the reactor.

When the diameter of the auxiliary substrate for insulation is greater than or equal to 1/6 of the diameter of the reactor, the auxiliary substrate for insulation is spaced apart from the substrate by a distance equal to or greater than 2/3 of the diameter of the reactor, and the auxiliary substrate for insulation may be located within the range of the heating unit.

The auxiliary substrate for thermal insulation may be of a cotton or a net structure.

The auxiliary substrate for thermal insulation may have a structure provided with a through hole in the center.

The auxiliary substrate for thermal insulation may be at a lower temperature than the substrate.

The reactor may further include a substrate height adjusting device for adjusting the position of the substrate.

The vertical chemical vapor deposition reactor may deposit alpha gallium oxide on the substrate.

According to an embodiment of the present invention, a uniform deposition can be performed with a fast reaction rate using a liquid aerosol.

According to an embodiment of the present invention, it can be deposited while maintaining a temperature sufficient for the reaction while reacting using a liquid aerosol.

According to an embodiment of the present invention, it is possible to uniformly contact the liquid aerosol on the entire surface of the substrate while maintaining the temperature of the substrate uniformly.

1 is a side perspective view of a bottom-up vertical chemical vapor deposition apparatus according to an embodiment of the present invention.
2 is a side perspective view of a top-down vertical chemical vapor deposition apparatus according to another embodiment of the present invention.
3 is a simulation photograph showing the flow of an internal liquid aerosol of a vertical chemical vapor deposition machine and a distribution diagram showing the deposition concentration.
4 is a thermal image diagram showing the temperature distribution for each position of the auxiliary substrate for thermal insulation of the vertical chemical vapor deposition machine according to an embodiment of the present invention.
5 is a graph showing a temperature 1.5 cm below the growth surface and a graph of heat retention rate 1.5 cm below the growth surface according to the size and temperature of the auxiliary substrate for thermal insulation of the vertical chemical vapor deposition machine according to an embodiment of the present invention.
6 is a plan view of various types of auxiliary substrates for thermal insulation according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

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

1 is a side perspective view of a bottom-up vertical chemical vapor deposition apparatus according to an embodiment of the present invention.

Referring to FIG. 1 , the bottom-up vertical chemical vapor deposition apparatus includes a gas injection unit 110 for injecting a carrier gas, one side connected to the gas injection unit 110 and a water tank containing a precursor solution, and a precursor solution to the carrier gas. The liquid aerosol 130 is connected to the other side of the mist providing unit 120 having a spray vibrator 125 for spraying in the state, the mist providing unit 120, and extends vertically so that the liquid aerosol 130 moves vertically. A heating unit 170 for heating the substrate 160, the reactor 150 and the substrate 160 arranged to come into contact with the liquid aerosol 130 on the vertical movement path of the reactor 150 and the liquid aerosol 130. include

According to the above structure, since the reactor 150 vertically moves the liquid aerosol 130 as a flow path in which the reaction occurs, the direction in which the liquid aerosol 130 touches the substrate 160 is vertically downward or vertically upward. Since the liquid aerosol 130 does not flow in the horizontal direction, layer formation in which heavy air sinks does not occur. Therefore, it is possible to use the liquid aerosol 130 having a sinking property, but the deposition without the formation of a layer is possible.

Each configuration and operation principle according to the flow of the carrier gas will be described respectively.

In the case of the chemical vapor deposition method using the liquid aerosol 130, it may be driven at atmospheric pressure. Therefore, it can be used as a carrier gas by introducing external air at normal pressure. In particular, when a large bandgap is required, such as a power semiconductor, an oxide semiconductor is sometimes used. In this case, external air mainly composed of oxygen and nitrogen can be used directly after being purified by a filter. Specifically, a cover 115 having an open structure capable of adjusting the height is provided on the upper portion, and an air intake 113 that is an open gap is formed in the gas injection unit 110 to control the amount of outside air. .

Since the ratio of oxygen and nitrogen in the outside air is specified as 2:8, there may be difficulties in controlling the ratio of oxygen. The gas injection unit 110 may further include a gas injection tube 117 for injecting oxygen or inert gas in order to reduce or add oxygen ratio.

Through the above structure, a gas in which external air and an inert gas are mixed is used as a carrier gas. The carrier gas moves from the gas injection unit 110 to the mist providing unit 120 including a water tank containing the precursor solution. The water tank is provided with a spray vibrator 125 to spray the precursor solution in a liquid aerosol 130 state. The size of the liquid aerosol 130 is determined by the frequency of the spray vibrator 125, and it is preferable to spray it with a sufficiently fine size to ensure homogeneity during deposition. The spray vibrator 125 may vibrate at a frequency of 2.4 MHz or higher. When water or alcohol is sprayed with a frequency of 2.4 MHz or higher, it can be sprayed with droplets with a size of about 3 μm or less. Droplets of 3 μm or less do not sink and have a size that can float in the air, so they can maintain a liquid colloidal state for a relatively long time.

The solvent of the precursor solution will be different depending on the type of the precursor, but when the deposition layer is a metal oxide or the like, a precursor to which a metal ion is bound may be used as the precursor. The solvent of the precursor solution to which the metal ions are bound may be water or alcohol capable of dissolving the ions. Since the solvent of the precursor solution has a smaller latent heat, it is preferable that the solvent volatilizes easily upon heating.

The anion of the precursor solution may be acetylacetonate or chloride. In the case of acetylacetonate or chlorite, an aqueous solution can be easily prepared with a little acid, and stability is high because other risk factors such as fire are low, so it is particularly advantageous in the present invention using an aqueous solution state and a high reaction temperature. In addition, the metal bound to the precursor solution may be gallium (Ga). When it is reacted with oxygen as a precursor in which chloride or the like is combined with gallium, alpha gallium oxide can be deposited. Gallium oxide has five crystal structures according to its crystal structure. Among them, alpha gallium oxide has the largest bandgap, which is advantageous for power semiconductor utilization, but is more unstable than beta gallium oxide. However, if the reaction temperature (500° C.) is precisely controlled, only alpha gallium oxide can be selectively deposited. Therefore, alpha gallium oxide can control the temperature of the reaction surface to a high level, and is particularly suitable for the present technology.

However, the deposition material to which this technology can be applied is not limited to gallium oxide. This synthesis method using liquid colloid can construct equipment at low cost with a vacuum-free structure, and thus a simple oxide growth system can be constructed as a whole. By using the precursor as a solution, it can be uniformly mixed when mixed with other elements and grown at a low temperature, so it is particularly suitable for oxide semiconductors such as sapphire and MgO, and is also suitable for power semiconductors with precise mixing ratios and large band gaps like SiC. Suitable. Any other material for deposition can be applied.

The carrier gas containing the liquid aerosol 130 may be provided with the reactor 150 vertically upward without horizontal movement, and in this case, the carrier gas may be vertically moved without horizontal movement.

The carrier gas containing the liquid aerosol 130 moves to a portion of the reactor 150 heated by the heating unit 170 . The reactor 150 is preferably transparent to infrared and visible light so that the heat of the heating unit 170 can be transmitted smoothly, and must have heat resistance.

The heating unit 170 may be an electric heater, high-frequency induction, infrared radiation, or laser. The heating unit 170 may selectively heat only the substrate 160 and the auxiliary substrate 163 for thermal insulation through high-frequency induction, infrared radiation, and laser irradiation. The above-described method may be employed to selectively cause only the surface reaction of the substrate 160 . However, the heating method of the heating unit 170 is not limited thereto, and a method of heating the entire reactor 150 such as an electric heater method may be employed.

In the case of the present invention using the liquid aerosol 130, the solvent of the liquid aerosol 130 must first be evaporated, and secondarily, the powder in the solid aerosol 140 state must react on the substrate 160 surface. In other words, a double heating structure is required. The temperature for allowing the liquid aerosol 130 to evaporate will be different depending on the type of solvent, but it is relatively low, and the temperature for the reaction on the substrate 160 is high. Therefore, it is preferable to use a heating method of heating the entire reactor 150 to a low temperature and heating the substrate 160 to a high temperature together. To this end, it is possible to form a double heating structure in a configuration including an electric heater and a high frequency induction device at the same time.

The liquid aerosol 130 is introduced into the reactor 150 heated by the heating unit 170 . A liquid aerosol 130 approaches the heated substrate 160 closely. At this time, the solvent of the liquid aerosol 130 evaporates, leaving only the precursor. The precursor is deposited by contacting and reacting with the hot substrate 160 as a solid aerosol 140 .

If the temperature of the substrate 160 can be infinitely increased, there will be no problem, but the temperature of the substrate 160 may have only an appropriate reaction temperature according to the material of the target deposition layer. In particular, when a plurality of allotropes can be produced by the same reaction formula as in gallium oxide, the reaction temperature may be selected within a limited range. Therefore, when the reaction temperature is low, all of the liquid aerosol 130 may not be evaporated with only the temperature of the substrate 160 , and when the liquid aerosol 130 approaches the substrate 160 close to the substrate 160 , the substrate 160 rapidly There may be cases in which heat is lost and the reaction temperature cannot be maintained. In order to solve this problem, an auxiliary substrate 163 for thermal insulation may be further provided between the substrate 160 and the mist providing unit 120 . Specific experimental examples for this will be described later with reference to FIGS. 3 and 4 .

The auxiliary substrate 163 for thermal insulation serves to evaporate the solvent of the liquid aerosol 130 and pre-heat the solid aerosol 140, and it is preferable to avoid the reaction. Therefore, it is preferable that the auxiliary substrate 163 for thermal insulation is heated at a lower temperature than the substrate 160 .

The diameter of the auxiliary substrate 163 for insulation and the separation distance between the auxiliary substrate 163 for insulation and the substrate 160 is 1.5 cm from one surface of the substrate 160 where the liquid aerosol 130 touches. The heat retention rate is 50 % or more. For example, the auxiliary substrate 163 for thermal insulation is spaced apart from the substrate 160 by 1.5 to 5 cm and may have a diameter of 0.5 to 3 inches, and the auxiliary substrate 163 for thermal insulation is separated from the substrate 160 by 10 to 20 cm. When spaced apart, they may be 1-5 inches in diameter.

The auxiliary substrate 163 for thermal insulation may have a planar shape, but may have a net structure or a structure in which a through hole 620 is provided in the center.

The auxiliary substrate 163 for thermal insulation provides heat to the liquid aerosol 130 so that the liquid aerosol 130 can be completely evaporated.

The substrate 160 may be perpendicular to the movement direction of the carrier gas, but may be disposed at an angle to the movement direction of the carrier gas at a predetermined angle to prevent vortex and facilitate movement of the carrier gas. In addition, the substrate 160 may further include a substrate height adjusting device 167 to adjust a relative position with the heating unit 170 in the reactor 150 .

The carrier gas in which the reaction is completed in the substrate 160 is discharged to the outside through the fan 180 . Carrier gases contain fine aerosols and can be harmful to the operator's body. Therefore, it is preferable that the carrier gas moves by applying a negative pressure inside the device to prevent the carrier gas from coming out of the device. The means for applying the negative pressure at the final outlet may be a pump or a fan, and the vertical chemical vapor deposition apparatus may further include a filter in order to detoxify the exhaust gas.

2 is a side perspective view of a top-down vertical chemical vapor deposition apparatus according to another embodiment of the present invention.

Referring to FIG. 2 , the top-down vertical chemical vapor deposition apparatus includes the same configuration as the bottom-up vertical chemical vapor deposition apparatus described with reference to FIG. 1 . That is, the gas injection unit 110 for injecting the carrier gas, one side is connected to the gas injection unit 110 and includes a water tank containing the precursor solution, and for spraying the precursor solution to the carrier gas in the liquid aerosol 130 state. A mist providing unit 120 having a spray vibrator 125, connected to the other side of the mist providing unit 120, a reactor 150 extending vertically so that the liquid aerosol 130 moves vertically, liquid aerosol 130 ) comprising a substrate 160 arranged to come into contact with the liquid aerosol 130 on a vertical movement path, a reactor 150 and a heating unit 170 for heating the substrate 160, comprising a vertical chemical vapor deposition machine .

However, one end of the reactor 150 connected to the mist providing unit 120 is the upper part of the reactor 150 , and the liquid aerosol 130 moves vertically downward from the upper part of the reactor 150 and is deposited on the substrate 160 . It is different from bottom-up vertical chemical vapor deposition.

3 is a simulation photograph showing the flow of the liquid aerosol 130 inside the vertical chemical vapor deposition machine and a distribution diagram showing the deposition concentration.

FIG. (a) is a simulation photograph showing the flow of the carrier gas when the carrier gas is introduced into the substrate 160 . The arrow indicates the direction of movement of the carrier gas, and the density of the shade indicates the velocity. It can be seen that with respect to the carrier gas traveling upward, there is little flow of air in the inner portion 310 of the substrate, and it moves at a very high speed in the outer portion 320 of the substrate. This is because a flow path through which the carrier gas touching the inner portion 310 of the substrate can smoothly escape is not formed. The temperature of the inner portion of the substrate 310 is maintained because the carrier gas heated to a high temperature does not move, and the temperature of the outer portion 320 of the outer portion of the substrate 320 is rapidly lowered because a new carrier gas continues to flow in and take heat away. have. Looking at the distribution diagram of the substrate 160 on which the actual deposition has been performed in FIG. (b), it can be seen that the reaction of the edge of the substrate 330 is reduced and the deposition is performed at a low density.

4 is a thermal image diagram showing a temperature distribution for each position of an auxiliary substrate for thermal insulation of a vertical chemical vapor deposition machine according to an embodiment of the present invention.

FIG. (a) is a thermal image diagram showing a case in which there is no auxiliary substrate 163 for thermal insulation. Although heat is supplied by the heating unit 170 , the liquid aerosol 130 is hardly heated due to this. Most of the liquid aerosol 130 is heated by the substrate 160 . Accordingly, the substrate 160 loses a large amount of heat, so that the temperature near the surface of the substrate 160 drops to a low level. Therefore, there is a risk that the edge may not reach the reaction temperature depending on the position on the surface of the substrate 160 .

FIG. (b) is a thermal image diagram illustrating a case in which the auxiliary substrate 163 for thermal insulation is provided at a position (5 cm) close to the substrate 160. As shown in FIG. The auxiliary substrate 163 for thermal insulation supplies heat to the carrier gas flowing into the substrate 160 , and serves to evaporate the liquid aerosol 130 included in the carrier gas and heat the carrier gas. When the auxiliary substrate 163 for insulation is close to the substrate 160 , the heat provided from the auxiliary substrate 163 for insulation is easily maintained between the auxiliary substrate 163 and the substrate 160 for insulation. However, since a flow path through which the carrier gas can enter is not formed between the auxiliary substrate 163 and the substrate 160 for thermal insulation, a problem may occur that the carrier gas may not properly contact the center of the substrate 160 .

FIG. (c) is a thermal image diagram illustrating a case in which the auxiliary substrate 163 for thermal insulation is separated from the substrate 160 by 10 cm or more. When the auxiliary substrate 163 for insulation is separated from the substrate 160, the carrier gas heated by the auxiliary substrate 163 for insulation is dispersed by the carrier gas mixed between the auxiliary substrate 163 and the substrate 160 for insulation. all. Therefore, the heat provided by the auxiliary substrate 163 for thermal insulation is not completely transferred to the front portion of the substrate 160 . However, if the auxiliary substrate 163 for thermal insulation is large enough, more heat can be provided, so that the amount of heat transferred to the front portion of the substrate 160 is also increased.

5 is a graph showing a temperature 1.5 cm below the growth surface and a heat retention rate graph 1.5 cm below the growth surface according to the size and temperature of the auxiliary substrate 163 for thermal insulation of the vertical chemical vapor deposition machine according to an embodiment of the present invention. The temperature within 1.5 cm of the growth surface is directly affected by radiant heat of the growth surface, and the temperature within 1.5 cm of the growth surface is mainly affected by the temperature of the growth surface. Therefore, the temperature fluctuation of the growth surface can be measured relatively precisely by measuring the temperature within 1.5 cm of the growth surface.

The experimental results show the reaction results in the reactor 150 having a diameter of 6 inches. As the temperature drop due to the high-velocity fluid is a key variable influencing the temperature of the substrate 160 , the structure of the flow path is important. The structure of the flow path is determined by the diameter of the substrate 160 , the auxiliary substrate for thermal insulation 163 , and the distance between the substrate 160 and the auxiliary substrate for thermal insulation 163 . Since the diameter of the reactor 150 determines the size of the entire flow path, the size of each component relative to the diameter of the reactor 150 is important.

According to FIG. 5 , when the auxiliary substrate 163 for thermal insulation is provided at a point 5 cm from the substrate 160 , the temperature and heat retention rate are remarkably high compared to the case where the auxiliary substrate 163 is dropped by 10 cm or more.

It is preferable that the temperature of the 1.5 cm point from the substrate 160 shows a heat retention rate of 50% or more as much as possible. When it is lower than this, there may be a case in which all of the solvent of the liquid aerosol 130 is not evaporated until it touches the substrate 160 , just like the substrate 160 is opened to the liquid aerosol 130 as it is.

When the auxiliary substrate 163 for thermal insulation is provided at the 5 cm point, a heat retention rate of 50% is exhibited when the thickness is 0.5 inches. Therefore, when the auxiliary substrate 163 for insulation is provided closer than 5 cm, it is sufficient to provide the auxiliary substrate 163 for insulation with a diameter of 0.5 inches or more. However, when the auxiliary substrate 163 for thermal insulation is provided at a point closer than 1.5 cm, the auxiliary substrate 163 for thermal insulation may cover the substrate 160, and even if it exceeds 3 inches, the auxiliary substrate for thermal insulation ( 163) and the substrate 160 does not easily enter the carrier gas, thereby reducing the deposition efficiency. In addition, when the distance between the substrate 160 and the auxiliary substrate 163 for insulation on the graph is 5 cm, when the size of the auxiliary substrate 163 for insulation exceeds 3 inches, the effect of increasing the temperature and heat retention rate converges, so the insulation assistance The size of the substrate 163 does not need to be 3 inches or more.

Here, since the size of the reactor 150 is 6 inches, the diameter of 5 cm of the auxiliary substrate 163 for insulation corresponds to 1/3 of the diameter of the reactor 150, and the diameter of 0.5 inches is 1/12, 3 of the diameter of the reactor 150 The diameter in inches corresponds to one-half the diameter of the reactor 150 . Therefore, it is preferable that the auxiliary substrate 163 for thermal insulation is spaced apart from the substrate 160 by a size of 1.5 cm or more and 1/3 or less of the diameter of the reactor, and the diameter is 1/12 or more and 1/2 or less of the diameter of the reactor 150 .

On the other hand, when spaced apart from the substrate 160 by 10 cm or more, a result of linearly increasing the heat retention rate according to the size of the substrate 160 is obtained. In other words, the heat provided by the auxiliary substrate 163 for insulation is diluted throughout the reactor 150 and only affects the substrate 160 , and the effect of being trapped in the area between the auxiliary substrate 163 and the substrate 160 for insulation does not occur Exceeding 50% of the heat retention rate corresponds to about 1 inch, and since the size of the auxiliary substrate 163 for insulation has no upper limit other than the diameter of the reactor 150, the size of the auxiliary substrate 163 for insulation is 1 inch or more. It is preferably smaller than the diameter of

Here, since the size of the diameter of the reactor 150 is 6 inches, the diameter of 10 cm of the auxiliary substrate 163 for thermal insulation corresponds to 2/3 of the diameter of the reactor 150 . Also, one inch diameter corresponds to 1/6 the diameter of reactor 150 . Therefore, according to this experiment, when the diameter of the auxiliary substrate 163 for insulation is equal to or greater than 1/6 of the diameter of the reactor 150, the auxiliary substrate 163 for insulation is equal to or greater than 2/3 of the diameter of the reactor 150. Or, if it is spaced apart from the substrate 160 by a large distance and is located within the range of the heating unit 170, the heat retention rate can be maintained higher than 50%.

In addition, when the separation distance is 10 cm or more and the diameter of the auxiliary substrate 163 for insulation exceeds 3 inches or more, the order of magnitude of the heat retention rate is different from the separation distance order. (10 cm > 15 cm = 20 cm) This is because the reactor 150 is located in the heating unit 170 even after the auxiliary substrate 163 for thermal insulation, so there is no room for heat loss according to the distance to be reflected because the heat loss is small, and the separation distance This is because the effect of heat transfer by radiation is rapidly reduced when is farther away, and the difference in heat retention rate according to the separation distance disappears. Therefore, when the diameter of the auxiliary substrate 163 for thermal insulation exceeds 3 inches, if the separation distance is equal to or greater than 10 cm, the separation distance as long as the auxiliary substrate 163 for insulation is included in the region surrounded by the heating unit 170 . Regardless, it shows high heat preservation efficiency of over 70%.

Here, 3 inches corresponds to 1/2 the diameter of the reactor 150 and 10 cm corresponds to 2/3 the diameter of the reactor 150 . Therefore, when the auxiliary substrate 163 for thermal insulation is greater than or equal to 1/2 of the diameter of the reactor 150, the auxiliary substrate 163 for insulation is equal to or greater than 2/3 of the diameter of the substrate 160 and the reactor 150. It is spaced apart by a distance, and is located within the range of the heating unit 170 to maintain a heat retention rate higher than 70%.

As described above, it is very important to precisely control the reaction temperature in the substrate 160 in the case of gallium oxide having several allotropes. However, in the case of the MIST deposition method using a liquid colloid, since the temperature fluctuation of the substrate 160 is relatively large due to the liquid colloid, the temperature of the substrate 160 is maintained at 700°C, 200°C higher than the actual reaction temperature (500°C). In the case of , a phenomenon in which the temperature of the substrate 160 is lower than the reaction temperature is prevented. When the auxiliary substrate 163 for thermal insulation is used, the temperature fluctuation of the substrate 160 can be extremely reduced, so that the temperature of the substrate 160 can be lowered close to the reaction temperature to react.

6 is a plan view of various types of auxiliary substrates for thermal insulation according to an embodiment of the present invention.

In Figs. 4 and 5, it was assumed that the auxiliary substrate 163 for thermal insulation had a planar structure as shown in Fig. (a) and an experiment was performed. However, the auxiliary substrate 163 for thermal insulation does not necessarily have to have a flat shape.

The auxiliary substrate 163 for thermal insulation may eventually function as an obstacle covering the front surface of the substrate 160 , and in particular, serves to block the flow path toward the inner portion 310 of the substrate. Therefore, it is preferable to have a structure that secures the flow path of the carrier gas flowing to the substrate 160 .

For example, since it is difficult to secure a flow path in the inner portion of the substrate 310 , the carrier gas tends to stagnate at a high temperature. Accordingly, more carrier gas flows through the inner portion 310 of the substrate to induce a uniform temperature throughout the substrate 160 . To this end, the auxiliary substrate 163 for thermal insulation may have a through hole 620 in the center.

Alternatively, in order to disperse the effect of blocking the carrier gas directed to the substrate 160, the surface of the auxiliary substrate 163 for thermal insulation may be provided in the form of a net.

The vertical chemical vapor deposition apparatus according to an embodiment of the present invention has the effect of improving the reaction rate by using the liquid aerosol 130 .

The vertical chemical vapor deposition apparatus according to an embodiment of the present invention has an effect of uniformly depositing on a large area by forming a flow path through which the carrier gas including the liquid aerosol 130 moves vertically.

The vertical chemical vapor deposition machine according to an embodiment of the present invention has an effect of evaporating all of the solvent before the liquid aerosol 130 touches the substrate 160 by having the auxiliary substrate 163 for thermal insulation.

The vertical chemical vapor deposition apparatus according to an embodiment of the present invention prevents the liquid aerosol 130 from approaching the substrate 160 , thereby preventing a rapid decrease in the reaction temperature of the substrate 160 .

The vertical chemical vapor deposition apparatus according to an embodiment of the present invention precisely controls the temperature during the reaction, so that only a specific compound among compounds having various allotropes according to the reaction temperature can be deposited with high purity.

The vertical chemical vapor deposition apparatus according to an embodiment of the present invention limits the size of the auxiliary substrate 163 for thermal insulation and the distance from the substrate 160, thereby maintaining a constant temperature of the substrate 160 and not blocking the carrier gas. It works.

The vertical chemical vapor deposition machine according to an embodiment of the present invention has an air intake 113 having an adjustable height cover 115, thereby easily controlling the ratio of external air and inert gas.

The description of the present invention described above is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

110: gas injection unit 113: air intake
115: cover 117: gas injection tube
120: mist providing unit 125: atomizing vibrator
130: liquid aerosol 140: solid aerosol
150: reactor 160: substrate
163: auxiliary substrate for warming 167: substrate height adjustment device
170: heating unit 180: fan
310: inner portion of the substrate 320: outer portion of the substrate
330: substrate edge 620: through hole
630: net structure

Claims (10)

a gas injection unit for injecting a carrier gas;
a mist providing unit having one side connected to the gas injection unit and including a water tank containing a precursor solution, and having a spray vibrator for spraying the precursor solution to the carrier gas in a liquid aerosol state;
a reactor connected to the other side of the mist providing part and extending vertically so that the liquid aerosol moves vertically;
a substrate disposed to contact the liquid aerosol on a vertical movement path of the liquid aerosol; and
and a heating unit for heating the reactor and the substrate. According to claim 1,
The reactor further comprises an auxiliary substrate for thermal insulation positioned between the substrate and the mist providing unit, a vertical type chemical vapor deposition machine. 3. The method of claim 2,
The diameter of the auxiliary substrate for thermal insulation and the separation distance between the auxiliary substrate for thermal insulation and the substrate are determined such that the heat retention rate at a point spaced 1.5 cm from one surface of the substrate to which the liquid aerosol touches is 50% or more, vertical chemistry evaporator. 4. The method of claim 3,
The auxiliary substrate for thermal insulation is spaced apart from the substrate by 1.5 cm or more and less than 1/3 of the diameter of the reactor, and the diameter is 1/12 or more and 1/2 or less of the diameter of the reactor. 4. The method of claim 3,
When the diameter of the auxiliary substrate for insulation is greater than or equal to 1/6 of the diameter of the reactor, the auxiliary substrate for insulation is spaced apart from the substrate by a distance equal to or greater than 2/3 of the diameter of the reactor, and the auxiliary substrate for insulation is A vertical chemical vapor deposition machine located within the range of the heating unit. 3. The method of claim 2,
The auxiliary substrate for thermal insulation is a plane or a net structure, a vertical chemical vapor deposition machine. 3. The method of claim 2,
The auxiliary substrate for thermal insulation has a structure provided with a through hole in the center, a vertical type chemical vapor deposition machine. 3. The method of claim 2,
The auxiliary substrate for thermal insulation is a lower temperature than the substrate, vertical chemical vapor deposition machine. According to claim 1,
The reactor further comprises a substrate height adjustment device for adjusting the position of the substrate. According to claim 1,
wherein the vertical chemical vapor deposition reactor deposits alpha gallium oxide on the substrate.

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