KR100695536B1 - Chemical vapor deposition system having dual substrate - Google Patents

Abstract

A CVD apparatus having a dual substrate is provided to easily control the impurities generated in growing a thin film by preparing substrates on the upper and the lower surface of an inner path of a heating body through which material and diluent gases flow. A quartz pipe(310) is prepared as a reaction chamber for growing a thin film by an RF induction heating. An RF coil(320) for RF induction heating is installed on the outer circumferential surface of the quartz pipe. A heating body(330) supports and fixes a substrate for growing a thin film, supplying a path through which material and diluent gases(360) for CVD pass and inductively heated by the RF coil. An adiabatic material(340) blocks the heat generated from the heating body from the outside, installed between the inner circumferential surface of the quartz pipe and the heating body. Substrates(350a,350b) for growing a silicon carbide epitaxial thin film are formed on the upper and the lower surfaces of an inner path(330h) of the heating body. The adiabatic material doesn't come in contact with the inner wall of the quartz pipe so that mixture gas of the material gas and the diluent gas can flow to the inner path of the heating body and a space between the inner wall of the quartz pipe and the outer wall of the heating body.

Description

Chemical vapor deposition apparatus having a dual substrate {Chemical vapor deposition system having dual substrate}

1 and 2 are views showing the structure of a conventional horizontal silicon carbide epitaxy thin film growth apparatus.

3 is a view showing the overall configuration of a chemical vapor deposition apparatus having a double substrate according to the present invention.

4 is a partial excerpt view showing the inner passage of the heating element of the chemical vapor deposition apparatus of FIG.

FIG. 5 is a view showing an example in which a chemical vapor deposition apparatus having a double substrate of the present invention is configured such that a heat insulator is not in contact with an inner wall of a quartz tube. FIG.

6 to 9 are views showing various examples in which the upper surface or the lower surface of the inner passage of the heating element is inclined at an angle in the chemical vapor deposition apparatus having the double substrate of the present invention.

<Explanation of symbols for the main parts of the drawings>

110,210,310 ... Quartz 120,220,320 ... High frequency coil

130,230,330 ... heating elements 140,240,340

150,250,350a, 350b ... substrate 160,260,360

230h, 330h ... inner passage of heating element

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical vapor deposition apparatus, and in particular, by forming a substrate for thin film growth inside a heating element where compound semiconductor thin film growth occurs, on both the lower and upper sides of the heating element, the thin film growth proceeds simultaneously on both sides. Improve the efficiency of thin film growth, and control the impurities easily because the same substrate is also located on the upper side, and the process area is reduced by double the area of the substrate, enabling the thin film to be doubled in the same capacity device The present invention relates to a chemical vapor deposition apparatus having a double substrate.

In general, high temperature of 1500-1600 ° C. is required for epitaxial silicon carbide thin film growth, and chemical vapor deposition (CVD) is used. The silicon carbide epitaxy thin film growth is in the form of induction heating using high frequency (RF) to maintain high temperature and high temperature in an atmosphere without oxidizing gas (eg, oxygen). At this time, high density graphite is used as the heating element. As the source gas, SiH ₄ and Si ₂ H ₆ are used as raw materials of silicon. CH ₄ , C ₂ H ₆ , C ₃ H ₈ , which are the raw materials of gas and carbon Etc. are used a lot. Recently, trimethylsilane (TMS) and bistrimethylsilyl methan (BTMSM) containing silicon and carbon in a single chemical species have been used. Gases having high heat transfer coefficients, such as hydrogen or helium, are mainly used as delivery gases for smooth delivery of these source gases. In the case of hydrogen, it is highly flammable and requires much attention for the treatment of the gas after the reaction. In order to solve this problem, chemical vapor deposition using helium gas has recently been applied. However, since helium gas is expensive, it is rarely used in actual thin film deposition. In chemical vapor deposition, the flow of delivery gas in the reaction chamber must form a laminar flow.

In order to form a laminar flow, the Reynolds number, which is basically determined from the fluid velocity and the fluid viscosity coefficient, must be small as in the following equation.

(V = fluid mean velocity, D = diameter, ρ = fluid density, μ = fluid viscosity, respectively.)

This generally means that it is easy to form laminar flow when the gas flow rate is slow. However, in the case of the silicon carbide epitaxy thin film growth apparatus, since the growth temperature is high (1500-1600 ° C.), the convection force of the gas is increased to hinder these flows. Therefore, in the case of silicon carbide epitaxy thin film growth apparatus, the gas flow rate must be large enough to suppress the flow of gas due to convective force. At the same time, the low flow rate must be satisfied so that the inertial force is not too large for the viscous force. Several studies to date indicate that a gas flow suitable for epitaxial thin film growth is formed when the total flow rate (V) in the reaction chamber is in the range of 1 cm / sec <V <10 cm / sec.

1 and 2 is a view showing the structure of a conventional horizontal silicon carbide epitaxy thin film growth apparatus.

Referring to FIG. 1, the conventional high temperature chemical vapor deposition apparatus for thin film growth of silicon carbide epitaxy is manufactured to be used in a vacuum to suppress the inflow of oxidizing gas, and the reaction chamber is mainly used as a quartz tube 110. The graphite heating element 130, on which the silicon carbide substrate 150 may be mounted, is placed in the center of the quartz tube 110, and a porous heat insulating material 140 is positioned below it. In general, the heating element 130 at this time may be inclined at an angle with respect to the flow direction of the gas 160 at an angle α to suppress the effect of increasing the boundary region with respect to the flow of the gas. On the other hand, the high frequency (RF) coil 120 for induction heating is located outside the quartz tube 110. In addition, the outside of the quartz tube 110 is configured to maintain the temperature near room temperature with the help of cooling water or air. Source gases containing silicon and carbon are diluted with hydrogen gas and injected into the reaction chamber. The mixed gas 160 of the source gas and the hydrogen gas is supplied with high-temperature energy from the heating element 130 while passing through the heating element 130 to increase the temperature. At this time, since the temperature in the upper portion of the quartz tube 110 is maintained near room temperature, the gas near the substrate 150 located at the center of the heating element 130 and the temperature near the quartz tube 110 are significantly different. do. Due to this temperature difference, the upward pressure of the gas due to convection from the vicinity of the substrate toward the quartz tube is increased. When forming a thin film by chemical vapor deposition, in particular when forming a single crystal thin film, the gas flow has to form a laminar flow on the substrate as described above, a lot of dilution gas is used for this. In order to compensate for this, the hot-wall type chemical vapor deposition apparatus of FIG. 2 is proposed.

Referring to FIG. 2, a passage 230h through which gas flows may be formed in the heat generating element 230, and the outside of the heat generating element may be surrounded by a heat insulating material 240. In this case, the heating element 230 exists not only in the lower portion of the heating element 230 on which the substrate 250 is placed, but also in the upper portion thereof, so that the gas temperature difference in the vicinity and the upper portion of the substrate 250 is reduced, resulting in turbulence of the gas flow due to convection. Has the effect of suppressing. The temperature distribution and the gas flow in the heating element 230 have almost the same distribution as the upper and lower portions, and thus a thin film is deposited on the upper wall of the heating element 230. The thin film on the upper wall of the heating element 230 formed as described above also changes the characteristics of the heating element and the temperature, velocity, and viscosity of the gas flowing in the heating element according to continuous thin film deposition, thereby inhibiting deposition of the thin film having the same characteristics, thereby reproducing the thin film. Hard to secure.

The present invention has been made in view of the above matters, and by forming a substrate for thin film growth inside the heating element where the compound semiconductor thin film growth occurs, on both sides of the lower and upper surfaces of the heating element so that the thin film growth proceeds simultaneously on both sides. Improve the efficiency of thin film growth, and control the impurities easily because the same substrate is also located on the upper side, and the process area is reduced by double the area of the substrate, enabling the thin film to be doubled in the same capacity device It is an object of the present invention to provide a chemical vapor deposition apparatus having a double substrate.

In order to achieve the above object, a chemical vapor deposition apparatus having a dual substrate according to the present invention,

It is installed on the quartz tube as a reaction chamber for thin film growth by high frequency induction heating, and on the outer circumferential surface of the quartz tube, and is installed inside the quartz tube for high frequency induction heating, and inside the quartz tube, It provides a flow path for raw material gas and diluent gas while supporting and fixing the substrate for thin film growth, and is installed between the heating element induction heating by the high frequency coil, the inner circumferential surface of the quartz tube and the heating element, generated from the heating element In the chemical vapor deposition apparatus having a heat insulating material for blocking the heat to the outside,

The upper surface and the lower surface of the inner passage of the heating element is characterized in that the substrate for the growth of silicon carbide epitaxy thin film is provided respectively.

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

3 and 4 show a chemical vapor deposition apparatus having a double substrate according to the present invention, Figure 3 is a view showing the overall configuration, Figure 4 is a portion showing the inner passage of the heating element and the substrate installed on the upper and lower surfaces Excerpt is also.

3 and 4, the chemical vapor deposition apparatus having a double substrate according to the present invention, a quartz tube 310 as a reaction chamber for thin film growth by high frequency induction heating, and the outer peripheral surface of the quartz tube 310 Installed in the high frequency coil 320 for high frequency induction heating, and installed inside the quartz tube 310, while providing a flow path for the raw material gas and dilution gas for chemical vapor deposition into the thin film growth Supporting and fixing the substrate for the, and is installed between the heating element 330 is induction heating by the high frequency coil 320, the inner circumferential surface of the quartz tube 310 and the heating element 330, generated from the heating element 330 It is basically provided with a heat insulating material 340 to block the heat.

However, in the chemical vapor deposition apparatus of the present invention, substrates 350a and 350b for thin film growth of silicon carbide epitaxy are respectively provided on the upper and lower surfaces of the inner passage 330h of the heating element 330. There is a characteristic.

Here, the source gas flowing into the inner passage 330h of the heating element 330 contains a gas containing silicon such as SiH ₄ , Si ₂ H ₆ , and carbon such as CH ₄ , C ₂ H ₆ , C ₃ H _8, and the like. One gas may be used, and diluent gas may be hydrogen or helium. In FIG. 3, reference numeral 360 denotes a mixed gas of source gas and hydrogen.

FIG. 5 illustrates an example in which a chemical vapor deposition apparatus having a double substrate of the present invention as described above is configured such that a heat insulating material does not come into contact with an inner wall of a quartz tube. In this embodiment, unlike the case of FIG. The mixed gas in which the source gas and the dilution gas (hydrogen) are mixed may flow into the space between the inner passage 330h of the heating element 330 and the inner wall of the quartz tube 310 and the outer wall of the heating element 330.

Meanwhile, FIGS. 6 to 9 are views showing various examples in which the upper surface or the lower surface of the inner passage of the heating element is inclined at a predetermined angle in the chemical vapor deposition apparatus having the double substrate according to the present invention.

First, as shown in FIG. 6, the inlet side of the lower surface 330b of the inner passage 330h of the heating element 330 may be configured to be inclined by the inclination angle α (for example, 1 ° to 30 °). As shown in FIG. 7, the inlet side of the upper surface 330a of the inner passage 330h of the heating element 330 may be configured to be inclined by the inclination angle β (for example, 1 ° to 30 °). Likewise, both the lower surface 330b and the inlet side of the upper surface 330a of the inner passage 330h of the heating element 330 may be inclined by the inclination angles α and β, respectively.

In addition, as shown in FIG. 9, unlike the above-described cases, the outlet side of the upper surface 330a of the inner passage 330h of the heating element 330 is inclined by the inclination angle δ (for example, 1 ° to 30 °). It can also be configured. In the case of FIG. 9, the gas flow inside the heating element 330 is not completely symmetrical, and when the convection force in the vertical direction has a greater influence, the substrate 350b disposed below and the substrate positioned above are located in the heating element 330. This is for adjusting the quality and thickness of the thin film deposited on the 350a.

Then, the epitaxial thin film growth using the chemical vapor deposition apparatus having a double substrate according to the present invention having the above configuration will be briefly described.

First, the inside of the quartz tube 310 as a reaction chamber is pumped with high vacuum so that an oxidizing gas and other impurity gases are not present in the quartz tube 310. After the dilution gas (hydrogen or helium) is injected into the quartz tube 310 to reach a proper pressure (for example from 100 Torr to atmospheric pressure) and maintained. When the proper pressure is maintained, power is applied to the high frequency coil 320 so that the heating element 330 is induction heated. When the heating element 330 is induction heated to reach a desired growth temperature, an appropriate amount of source gas, such as SiH ₄ , C ₃ H _8, and the like, is injected into the quartz tube 310 with dilution gas. At this time, the growth temperature is used from 1200 ℃ to 1800 ℃, the flow rate of each raw material gas is adjusted in the range of 0.1 ~ 100sccm. The diluent gas mixed with the raw material gas injected at the growth temperature is heated to receive heat energy while flowing into the heating element 330, and upon reaching the substrates 350a and 350b, Si and C atoms are adsorbed from each raw material gas to form silicon carbide. (SiC) film is formed. In this way, when the growth of the thin film is performed for a desired time, the injection of the source gas is first blocked, and the power of the high frequency coil 320 is cut off so that the heating element 330 is gradually cooled. After the heating element 330 is sufficiently cooled, injection of the dilution gas is blocked and pumped using a vacuum pump. After being sufficiently pumped, an inert gas such as argon (Ar) or nitrogen is injected again and pumped again. After repeating this process several times, the pressure inside the quartz tube 310 is made into an atmospheric pressure state with an inert gas, and then the heating element 330 and the substrates 350a and 350b are taken out of the quartz tube 310 and the substrate 350a is removed. Remove 350b.

As described above, the chemical vapor deposition apparatus having a double substrate according to the present invention is provided with a substrate on both the upper and lower surfaces of the inner passage of the heating element flowing through the source gas and the diluent gas can easily control the impurities generated during growth. In addition, thin film growth proceeds simultaneously on both sides to increase the efficiency of thin film growth, and the area of the substrate is doubled, so that the thin film can be grown by twice the amount of the same capacity device, thereby reducing the process cost. There is this.

Claims (12)

It is installed on the quartz tube as a reaction chamber for thin film growth by high frequency induction heating, and on the outer circumferential surface of the quartz tube, and is installed inside the quartz tube for high frequency induction heating, and inside the quartz tube, It provides a flow path for raw material gas and diluent gas while supporting and fixing the substrate for thin film growth, and is installed between the heating element induction heating by the high frequency coil, the inner circumferential surface of the quartz tube and the heating element, generated from the heating element In the chemical vapor deposition apparatus having a heat insulating material for blocking the heat to the outside, Chemical vapor deposition apparatus having a dual substrate, characterized in that the substrate for growing a thin film of silicon carbide epitaxy is provided on the upper and lower surfaces of the inner passage of the heating element. The method of claim 1, The lower surface 330b of the inner passage 330h of the heating element 330 has an inclination angle α with respect to the horizontal plane at the inlet side thereof, and has a value ranging from 1 ° to 30 °. . delete The method of claim 1, The upper surface 330a of the inner passage 330h of the heating element 330 has an inclination angle β with respect to the horizontal plane at the inlet side thereof, and has a value ranging from 1 ° to 30 °. . delete The method of claim 1, The lower surface 330b and the upper surface 330a of the inner passage 330h of the heating element 330 have respective inclination angles α and β with respect to the horizontal surface of the inlet side thereof in a range of 1 ° to 30 °. Chemical vapor deposition apparatus having a dual substrate. delete The method of claim 1, The upper surface 330a of the inner passage 330h of the heating element 330 has an inclination angle δ with respect to the horizontal surface of the exit side of the heating element 330 having a value ranging from 1 ° to 30 °. . delete The method of claim 1, The heat insulating material is such that the mixed gas in which the source gas and the dilution gas are mixed flows into the space between the inner passage 330h of the heating element 330 and the inner wall of the quartz tube 310 and the outer wall of the heating element 330. Chemical vapor deposition apparatus having a dual substrate, characterized in that not to be in contact with the inner wall of the quartz tube. The method of claim 1, Chemical vapor deposition apparatus having a dual substrate, characterized in that any one of SiH ₄ , Si ₂ H ₆ and CH ₄ , C ₂ H ₆ , C ₃ H ₈ is used as the source gas. The method of claim 1, Chemical vapor deposition apparatus having a dual substrate, characterized in that any one of hydrogen or helium is used as the diluent gas.

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