Rutile-type germanium dioxide self-supporting substrate and method for manufacturing the same, rutile-type germanium dioxide template and method for manufacturing the same, rutile-type germanium dioxide-based device wafer and method for manufacturing the same, method for manufacturing germanium tetrachloride gas, method for manufacturing rutile-type germanium dioxide single crystals, and apparatus for manufacturing rutile-type germanium dioxide single crystals

Abstract

To provide a rutile-type germanium dioxide free-standing substrate and a method for producing the same, a rutile-type germanium dioxide template and a method for producing the same, a rutile-type germanium dioxide device wafer and a method for producing the same, a method for producing a germanium tetrachloride gas which can grow a rutile-type germanium dioxide crystal, a method for producing a rutile-type germanium dioxide monocrystal which can grow a rutile-type germanium dioxide crystal, and a device for producing a rutile-type germanium dioxide monocrystal which can grow a rutile-type germanium dioxide crystal.SOLUTION: A rutile-type germanium dioxide free-standing substrate comprises a rutile-type germanium dioxide monocrystal. In the germanium dioxide free-standing substrate, the planar density of macro defects appearing on the surface is 5000 / cm2 or less in at least a part of the plane.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rutile-type germanium dioxide self-supporting substrate and a method for manufacturing the same, a rutile-type germanium dioxide template and a method for manufacturing the same, a rutile-type germanium dioxide-based device wafer and a method for manufacturing the same, a method for manufacturing germanium tetrachloride gas, a method for manufacturing a rutile-type germanium dioxide single crystal, and an apparatus for manufacturing a rutile-type germanium dioxide single crystal. [Background technology]

[0002] Rutile germanium dioxide (hereinafter also referred to as "r-GeO2") is a material with a wide band gap of 4.8 eV, and first-principles calculations (first-principles band calculations) have shown that it is easily doped with p-type and n-type materials, making it a material currently attracting attention. r-GeO2 has the potential to lead to the realization of UV (ultraviolet) light-emitting devices with high current injection efficiency. Furthermore, r-GeO2 has a Barriga figure of merit, an indicator of suitability for power devices, which is several times larger than that of β-type gallium oxide (β-Ga2O3), known as a wide-bandgap semiconductor, thus holding potential for application as a next-generation power device.

[0003] To realize high-performance power devices, the preparation of high-quality self-supporting single-crystal substrates is essential. While liquid-phase, gas-phase, and solid-phase methods are known for obtaining single-crystal substrates, the liquid-phase method is generally considered suitable for obtaining large-diameter single-crystal substrates inexpensively. This is because conventional semiconductor substrates, such as silicon and gallium arsenide, are manufactured using the liquid-phase method. Liquid-phase methods include the melt method, in which a single crystal is grown by seeding a molten material; the aqueous solution method, in which a single crystal is grown by heating and concentrating an aqueous solution and then cooling it; the hydrothermal synthesis method, in which a single crystal is grown under pressure in an autoclave; and the flux method, in which a single crystal is grown by adding raw materials to a molten salt of a low-melting-point flux.

[0004] Non-patent document 1 describes the growth of rutile-type germanium dioxide crystals using the flux method. However, the GeO2 crystals obtained after approximately 15 days of growth were typically only 0.5 × 0.3 × 0.2 mm in size. 3 It was also noted that it was amber-colored due to oxygen deficiency, and that an additional week of annealing in an atmospheric environment was required for its recovery. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Lignie, A., et al., “Growth of Piezoelectric Water-Free GeO2 and SiO2-Substituted GeO2 Single-Crystals,” Inorganic Chemistry, August 29, 2011, Vol. 50, No. 19, pp. 9311-9317. [Overview of the project] [Problems that the invention aims to solve]

[0006] Therefore, until now, there have been no examples of growing large r-GeO2 crystals of a practical size (2 inches or more in diameter).

[0007] The present invention aims to provide a rutile-type germanium dioxide self-supporting substrate and a method for manufacturing the same, a rutile-type germanium dioxide template and a method for manufacturing the same, a rutile-type germanium dioxide-based device wafer and a method for manufacturing the same, a method for manufacturing germanium tetrachloride gas capable of growing rutile-type germanium dioxide crystals, a method for manufacturing a rutile-type germanium dioxide single crystal capable of growing rutile-type germanium dioxide crystals, and a manufacturing apparatus for a rutile-type germanium dioxide single crystal capable of growing rutile-type germanium dioxide crystals. [Means for solving the problem]

[0008] The present invention includes the following embodiments. [1] A rutile-type germanium dioxide self-supporting substrate made of a rutile-type germanium dioxide single crystal, wherein the in-plane concentration of macrodefects appearing on the surface is 5000 defects / cm² in at least a portion of the in-plane area. 2 A germanium dioxide self-supporting substrate characterized by the following: [2] A method for manufacturing a germanium dioxide self-supporting substrate by halide vapor phase growth, The first step is to prepare a support crystal substrate made of a single crystal, A second step involves supplying in-situ generated germanium tetrachloride gas and oxygen gas to the support crystal substrate, and epitaxially growing a growth crystal made of rutile-type germanium dioxide single crystal on the surface of the support crystal substrate. The process includes a third step of cutting a germanium dioxide self-supporting substrate made of a rutile-type germanium dioxide single crystal from the aforementioned grown crystal, The second step includes a raw material gas generation step comprising a first-stage reaction in which metallic germanium is reacted with chlorine gas or hydrogen chloride gas to produce germanium chloride gas, and a second-stage reaction in which the germanium chloride gas is reacted with chlorine gas to produce germanium tetrachloride gas. A method for manufacturing a germanium dioxide self-supporting substrate. [3] The method for manufacturing a germanium dioxide self-supporting substrate according to [2], wherein the partial pressure of the chlorine gas supplied in the second-stage reaction is determined based on the partial pressure of the chlorine gas or hydrogen chloride gas supplied in the first-stage reaction. [4] A germanium dioxide template comprising a support crystal substrate and a germanium dioxide layer made of a rutile-type germanium dioxide single crystal epitaxially grown on the support crystal substrate, wherein the in-plane concentration of macrodefects appearing on the surface of the germanium dioxide layer opposite to the support crystal substrate is 5000 defects / cm² in at least a portion of the in-plane area. 2 A germanium dioxide template characterized by the following: [5] A method for producing a germanium dioxide template by halide vapor phase growth, The first step is to prepare a support crystal substrate made of a single crystal, The second step involves supplying in-situ generated germanium tetrachloride gas and oxygen gas to the support crystal substrate, and epitaxially growing a growth crystal made of rutile-type germanium dioxide single crystal on the surface of the support crystal substrate. The second step includes a raw material gas generation step comprising a first-stage reaction in which metallic germanium is reacted with chlorine gas or hydrogen chloride gas to produce germanium chloride gas, and a second-stage reaction in which the germanium chloride gas is reacted with chlorine gas to produce germanium tetrachloride gas. A method for manufacturing germanium dioxide templates. [6] The method for producing a germanium dioxide template according to [5], wherein the partial pressure of the chlorine gas supplied in the second-stage reaction is determined based on the partial pressure of the chlorine gas or hydrogen chloride gas supplied in the first-stage reaction. [7] A germanium dioxide-based device wafer comprising a support crystal substrate and a germanium dioxide layer made of a rutile-type germanium dioxide single crystal epitaxially grown on the support crystal substrate, wherein the in-plane concentration of macrodefects appearing on the wafer surface is 5000 defects / cm² in at least a portion of the in-plane area. 2 A germanium dioxide-based device wafer characterized by the following: [8] A method for manufacturing germanium dioxide device wafers by halide vapor phase growth, The first step is to prepare a support crystal substrate made of a single crystal, The second step involves supplying in-situ generated germanium tetrachloride gas and oxygen gas to the support crystal substrate, and epitaxially growing a growth crystal made of rutile-type germanium dioxide single crystal on the surface of the support crystal substrate. The second step includes a raw material gas generation step comprising a first-stage reaction in which metallic germanium is reacted with chlorine gas or hydrogen chloride gas to produce germanium chloride gas, and a second-stage reaction in which the germanium chloride gas is reacted with chlorine gas to produce germanium tetrachloride gas. A method for manufacturing germanium dioxide-based device wafers. [9] A method for manufacturing a germanium dioxide-based device wafer according to [8], wherein the partial pressure of the chlorine gas supplied in the second-stage reaction is determined based on the partial pressure of the chlorine gas or hydrogen chloride gas supplied in the first-stage reaction.

[10] Germanium chloride gas (GeCl) is produced by reacting metallic germanium with chlorine gas or hydrogen chloride gas. x A first-stage reaction step includes a first-stage reaction that generates integers x from 1 to 4, The generated germanium chloride gas (GeCl y The second-stage reaction step includes a second-stage reaction in which a (1 to 3 integer) is reacted with chlorine gas to produce germanium tetrachloride gas, A method for producing germanium tetrachloride gas, comprising the following components.

[11] A method for producing germanium tetrachloride gas according to

[10] , wherein the partial pressure of the chlorine gas supplied in the second-stage reaction step is determined based on the partial pressure of the chlorine gas or hydrogen chloride gas supplied in the first-stage reaction step.

[12] A method for producing germanium tetrachloride gas according to

[11] , wherein the first-stage reaction step and the second-stage reaction step are carried out at 400 to 1000°C.

[13] A step of producing GeCl4 gas by a method for producing germanium tetrachloride gas described in any of

[10] to

[12] , The process involves growing a rutile-type germanium dioxide single crystal on a supporting crystal substrate by halide vapor phase growth using at least the aforementioned GeCl4 gas and O2 gas, A method for producing a rutile-type germanium dioxide single crystal, comprising the features described above.

[14] A method for producing a rutile-type germanium dioxide single crystal according to

[13] , wherein the step of growing the rutile-type germanium dioxide single crystal is performed at 600°C or higher.

[15] A process that repeats the following steps after the step of growing the rutile germanium dioxide single crystal: cutting off the top surface of the rutile germanium dioxide single crystal, and growing another rutile germanium dioxide single crystal on the top surface of the cut-off rutile germanium dioxide single crystal. The method for producing rutile-type germanium dioxide single crystal according to

[13] or

[14] , further comprising

[16] A reaction tube, A raw material gas generation unit disposed inside the reaction tube, generating germanium tetrachloride gas and supplying it onto a support crystal substrate, A growth unit disposed inside the reaction tube, growing a rutile-type germanium dioxide single crystal on the support crystal substrate, A first heating mechanism disposed outside the reaction tube, heating the raw material gas generation unit, [[ID=⑨]] A second heating mechanism disposed outside the reaction tube, heating the growth unit, comprising The raw material gas generation unit reacts metallic germanium with chlorine gas or hydrogen chloride gas to generate germanium chloride (GeCl x , where x is an integer from 1 to 4) gas in a first reaction chamber, Germanium chloride (GeCl y , where y is an integer from 1 to 3) gas and chlorine gas are reacted in a second reaction chamber to generate germanium tetrachloride gas, A manufacturing apparatus for rutile-type germanium dioxide single crystal, comprising

[17] Inside the second reaction chamber, a baffle plate for promoting the mixing of germanium chloride (GeCl y , where y is an integer from 1 to 3) gas and chlorine gas is disposed, the manufacturing apparatus for rutile-type germanium dioxide single crystal according to

[16] .

[18] In the growth unit, a rutile-type germanium dioxide single crystal is generated on the support crystal substrate by the reaction of GeCl4 gas and O2 gas, the manufacturing apparatus for rutile-type germanium dioxide single crystal according to

[16] or

[17] . [[ID=⒆]]

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a rutile-type germanium dioxide self-supporting substrate and a method for manufacturing the same, a rutile-type germanium dioxide template and a method for manufacturing the same, a rutile-type germanium dioxide-based device wafer and a method for manufacturing the same, a method for manufacturing germanium tetrachloride gas, a method for manufacturing a rutile-type germanium dioxide single crystal, and an apparatus for manufacturing a rutile-type germanium dioxide single crystal. Furthermore, the crystal growth method (flux method) described in Non-Patent Document 1 was impractical because the growth of rutile-type germanium dioxide crystals was slow. However, according to the method for producing rutile-type germanium dioxide single crystals and the apparatus for producing rutile-type germanium dioxide single crystals of the present invention, rutile-type germanium dioxide crystals can be grown at a sufficient growth rate. Furthermore, Non-Patent Document 1 states that the size of the GeO2 crystal is typically 0.5 × 0.3 × 0.2 mm. 3 However, according to the method for producing rutile-type germanium dioxide single crystals and the apparatus for producing rutile-type germanium dioxide single crystals of the present invention, it is possible to produce wafers with a diameter of 50 mm or more. [Brief explanation of the drawing]

[0010] [Figure 1] This graph shows the relationship between reaction temperature and the partial pressure of the product gas. [Figure 2] This graph shows the relationship between the reaction temperature and the equilibrium constant for each reaction. [Figure 3] This graph shows the relationship between the amount of additional Cl2 and the partial pressure of GeClx gas. [Figure 4] This graph shows the relationship between the amount of additional Cl2 and the GeClx gas flow rate. [Figure 5] This is a cross-sectional view showing an example of a manufacturing apparatus for r-GeO2 single crystals. [Figure 6] This is an example of a baffle board. [Modes for carrying out the invention]

[0011] The following describes in detail embodiments for carrying out the present invention. However, the present invention is not limited to the embodiments described below, and various modifications are possible as long as they do not depart from the spirit of the present invention.

[0012] [Technical Concept of the Invention] In previous technologies, the growth rate of r-GeO2 single crystals was slow, and the quality was not satisfactory. One method for rapidly growing r-GeO2 single crystals is halide vapor phase epitaxy (HVPE), which is also used in the production of gallium nitride (GaN) single crystal substrates. Possible reaction systems for producing r-GeO2 single crystals by the HVPE method include "GeCl4 + O2 → GeO2 + 2Cl2" or "GeCl4 + 2H2O → GeO2 + 4HCl". GeCl4 has also been used for Ge doping during the HVPE growth of GaN. GeCl4 is a liquid at room temperature (5-30°C) and has a relatively high vapor pressure, making it possible to supply it by bubbling from a bottle.

[0013] When the inventors deposited GeO2 as an HVPE film by bubbling GeCl4 and reacting it with O2, no major problems were observed with crystal growth itself. To ensure the reproducibility of the growth conditions, controlling the vapor pressure of GeCl4, i.e., controlling the temperature of the liquid in the bottle, is extremely important. Therefore, in the inventors' experiments, the bottle temperature was controlled using a readily available, general-purpose constant temperature bath. The bottles that could fit into this constant temperature bath were small in capacity (25g in this experiment), and when attempting to deposit a thick film of GeO2 (for example, about 600μm thick), the bottle would be emptied about every other time, requiring frequent replacement. One solution to this problem is to use a large-capacity bottle, but this has many problems, such as requiring a large space, a large constant temperature bath, a large amount of expensive refrigerant, and a long waiting time for the temperature to stabilize each time the raw material container is replaced.

[0014] As a solution to these problems, it is conceivable to use GeCl4 within the HVPE reactor. The inventors first attempted to produce Ge chloride by supplying Cl2 or HCl to elemental Ge, and then attempt to deposit a GeO2 HVPE film by reacting the obtained Ge chloride with oxygen. In this case, observation of the surface of the obtained GeO2 thin film revealed that it was covered with macrodefects such as polycrystalline regions and pits. The inventors carefully investigated these macrodefects and found that particles generated by the gas-phase reaction between Ge chloride and oxygen were the starting point. Thermodynamic analysis was performed to understand this phenomenon. As a result, in a temperature range where a sufficient reaction rate can be expected (e.g., 500°C to 800°C), the reaction between elemental Ge and Cl2 or HCl produces GeCl x (x is an integer from 1 to 4) is produced, but it was found that GeCl2 is the main one produced. Therefore, when the equilibrium constant for the reaction of GeCl, GeCl2 or GeCl3 with O2 to produce GeO2 was determined, it was found to be several orders of magnitude larger (more than 10 orders of magnitude depending on the film formation temperature) than the equilibrium constant for the reaction of GeCl4 with O2. From this, it was determined that the production of Ge chlorides other than GeCl4 is the cause of the growth problems. Further thermodynamic considerations were added, and the produced GeCl y We discovered that by reacting (where y is an integer from 1 to 3) with Cl2, it is possible to convert it to GeCl4, thereby enabling film deposition while preventing the occurrence of macrodefects.

[0015] Here, I will explain why O2 was used as the oxygen source instead of H2O. To grow thick films in a realistic amount of time, a certain growth rate is necessary. This requires a large amount of raw materials. A common method for supplying H2O is to bubble H2O, kept at a certain temperature, with an inert gas such as N2, and then send the vapor into the growth region. The amount of H2O supplied in this case can be determined by multiplying the ratio of atmospheric pressure to the saturated vapor pressure of H2O at that temperature by the bubbling flow rate. However, when supplying large quantities, the temperature change of the liquid due to the heat of vaporization becomes significant, making it difficult to control the actual supply amount. This also makes even slight changes in conditions difficult. Therefore, O2 was used instead of H2O. However, this does not mean that H2O gas cannot be used for GeO2 crystal HVPE; it simply means that O2 gas was considered more suitable.

[0016] The thermodynamic analysis procedure performed by the inventors is as follows: Specifically, thermodynamic analysis was performed by solving the following system of equations. (a) K1 = P GeCl4 / P 2 Cl2 However, in equation (a), K1 is the equilibrium constant of Ge + 2Cl2 = GeCl4, and P Cl2 , P GeCl4 These are the equilibrium partial pressures of Cl2 gas and GeCl4 gas, respectively. (b) K2 = P GeCl3 / P 1.5 Cl2 However, in equation (b), K2 is the equilibrium constant of Ge + 3 / 2Cl2 = GeCl3, and P GeCl3 This is the equilibrium partial pressure of GeCl3 gas. (c)K3=P GeCl2 / P Cl2 However, in equation (c), K3 is the equilibrium constant of Ge + Cl2 = GeCl2, and P GeCl2 This is the equilibrium partial pressure of GeCl2 gas. (d) K4 = P GeCl / P 0.5 Cl2 However, in equation (d), K4 is the equilibrium constant of Ge + 1 / 2Cl2 = GeCl, and P GeCl This is the equilibrium partial pressure of GeCl gas. (e)P GeCl4 +P GeCl3 +P GeCl2 +P GeCl +P Cl2 +P N2 =1 However, in equation (e), P N2 This represents the equilibrium partial pressure of the carrier gas (N2 gas). In this case, the reaction is assumed to occur at atmospheric pressure, and the total pressure is set to 1 atm. (f)(4P GeCl4 +3P GeCl3 +2P GeCl2 +P GeCl +2P Cl2 ) / 2P N2 =A It was assumed that A remained constant before and after the reaction. This is because no Cl precipitates after the reaction. A being constant means that calculating A using the equilibrium partial pressures of each gas species yields the same result as calculating it using the input partial pressures.

[0017] For example, P 0 Cl2 =0.2, P 0 N2 By solving this system of equations with =0.8, we obtained the relationship between the reaction temperature and the equilibrium partial pressure of the product gas after the reaction (horizontal axis: reaction temperature, vertical axis: equilibrium partial pressure of the product gas) as shown in Figure 1. Here P 0 Cl2 ,P 0 N2 These represent the partial pressure of the Cl2 gas input and the partial pressure of the N2 carrier gas input, respectively.

[0018] Figure 1 shows that at reaction temperatures above 500°C, where a practical reaction rate can be obtained in the reaction between elemental Ge and Cl2 gas, other Ge chlorides (GeCl, GeCl2, GeCl3) are predominantly generated rather than GeCl4.

[0019] Next, the inventors investigated the reaction between the Ge chloride produced and O2 gas. Figure 2 shows germanium chloride (GeClx The following shows the calculated equilibrium constants for each reaction with respect to the reaction temperature when GeO2 is produced by reacting gas (x = integers from 1 to 4) with oxygen (horizontal axis: reaction temperature, vertical axis: equilibrium constant of each reaction).

[0020] As shown in Figure 2, across the entire temperature range, the equilibrium constant of the reaction between GeCl4 gas and O2 gas (GeCl4+ and O2 = GeO2 + 2Cl2) is higher than that of GeCl. y It was found that the equilibrium constant for the reaction between (integers y=1~3) and O2 is large. A large equilibrium constant indicates that the reaction occurs easily. Therefore, it is thought that as soon as GeCly and O2 are mixed, a gas-phase reaction occurs, generating particles that are incorporated into the r-GeO2 single crystal grown on the supporting crystal substrate, becoming the starting point for macrodefects.

[0021] As mentioned earlier, in preliminary experiments on GeO2 growth, in which GeCl4 vapor was supplied by bubbling and reacted with O2, no macrodefects occurred. Therefore, the inventors considered the GeCl produced here. y I thought that this problem could be solved if we could convert (integers y = 1 to 3) into GeCl4.

[0022] The following are possible reactions that convert GeCl, GeCl2, and GeCl3 to GeCl4. GeCl + 3 / 2Cl2 = GeCl4 ... (1) GeCl2 + Cl2 = GeCl4 ... (2) GeCl3 + 1 / 2Cl2 = GeCl4 ... (3)

[0023] Therefore, we considered that if the gas produced from the preceding reaction could enter the next chamber before being supplied to the growth region, and react there with additionally supplied Cl2 gas via a separate line as shown in (1) to (3) (reactions in the subsequent stage), it could all be converted to GeCl4 and then used for growth. Here, we will refer to the preceding reaction as the first-stage reaction, and the subsequent reaction as the second-stage reaction. Thermodynamic analysis was performed to determine whether this second-stage reaction would occur sufficiently within the same temperature range as the first-stage reaction. The thermodynamic analysis was performed by solving the following system of equations. (g)K5=P GeCl4 / (P 1.5 Cl2 P GeCl ) (h)K6=P GeCl4 / (P Cl2 P GeCl2 ) (i) K7 = P GeCl4 / (P 0.5 Cl2 P GeCl3 ) (j)P GeCl +P GeCl2 +P GeCl3 +P GeCl4 +P Cl2 +P N2 =1 (k)(P GeCl +P GeCl2 +P GeCl3 +P GeCl4 ) / 2P N2 =B It was assumed that B remained constant before and after the reaction. This is because no Ge precipitated after the reaction. (l)(P GeCl +2P GeCl2 +3P GeCl3 +4P GeCl4 +2P Cl2 ) / 2P N2 =C It was assumed that the amount of carbon (C) remained constant before and after the reaction. This is because no chlorine precipitated after the reaction. The initial input amount was determined using the output from the first reaction stage. Specifically, the following calculations were performed.

[0024] First, calculate the first reaction step using equations (a) to (f) above at a reaction temperature of 500°C. Here, the supply amounts were set to Cl2 = 100 ccm and N2 = 400 ccm. That is, P 0 Cl2 =0.2atm, P 0 N2 = 0.8 atm. At this time, the equilibrium partial pressure of the gas output becomes the plot at 500 °C in Fig. 1. Using this, it is converted into the output flow rate. Since N2 is an inert gas, it does not contribute to the reaction. That is to say, the N2 flow rate should remain unchanged before and after the reaction. However, as the partial pressure, it changes for the following reasons. When GeCl4 is generated in the reaction of Ge and Cl2, 2 mol of Cl2 is required to generate 1 mol of GeCl4. Conversely, 2 mol of GeCl can be formed with 1 mol of Cl2. Among these effects, since the total pressure is calculated as 1, the input partial pressure and the output partial pressure of N2 will not match. Therefore, by multiplying the equilibrium partial pressure of each gas by P 0 N2 / P N2 and then multiplying by the total input flow rate of 500 ccm, it can be converted into the flow rate of each gas.

[0025] Actually, when calculating the flow rate of N2 output in the first-stage reaction, [total input flow rate 500 ccm] × P N2 × P 0 N2 / P N2 and it can be seen that it naturally becomes the same as the input N2 flow rate. When converting the equilibrium partial pressure at 500 °C into the flow rate in this way and calculating the total output flow rate, it was found that it decreased to about 487 ccm.

[0026] For the second-stage reaction, a mixed gas of N2 and Cl2 with a total flow rate of 500 ccm will be added in a separate line. At this time, the input partial pressure of each GeCl x (x = an integer from 1 to 4) gas was the one obtained by [GeCl x flow rate obtained by flow rate conversion] / (487 + 500). Regarding the Cl2 gas, since the equilibrium partial pressure after the first-stage reaction is almost zero, the input partial pressure of Cl2 in the second stage was the one obtained by [additional Cl2 flow rate in a separate line] / (487 + 500). <The equilibrium partial pressures of each gas after the reaction obtained for this additional Cl2 flow rate are shown in Fig. 3. Fig. 3 is a graph showing the calculation results of the equilibrium partial pressures of each germanium chloride gas when Cl2 is added to GeClx (x is an integer from 1 to 4) generated at 500 °C (horizontal axis: additional Cl2 amount, vertical axis: GeCl x gas partial pressure). Also, the result of converting this into flow rate in the same way as the above method is shown in Fig. 4. Fig. 4 is a graph showing the flow rates of each germanium chloride gas when Cl2 is added to GeCl x (x is an integer from 1 to 4) (horizontal axis: additional Cl2 amount, vertical axis: GeCl x gas flow rate).

[0027] As the additional Cl2 flow rate is increased, the flow rate of GeCl y (y is an integer from 1 to 3) decreases, the flow rate of GeCl4 increases, and when a certain additional amount is reached, the conversion to GeCl4 is almost complete. It was found that beyond the inflection point where the conversion to GeCl4 is complete, Cl2 simply remains in excess. From this, it is considered that this inflection point coincides with the Cl2 flow rate that is neither excessive nor insufficient for converting GeCl y (y is an integer from 1 to 3) output in the first-stage reaction to GeCl4. When seeking the flow rate that is neither excessive nor insufficient, from the above equations (1) to (3), [GeCl3 flow rate] × 0.5 + [GeCl2 flow rate] + [GeCl flow rate] × 1.5 It is found that it is obtained by, and at P 0 Cl2 = 0.2 and a reaction temperature of 500 °C, it is estimated to be 74.3 ccm, which agrees well with the value at the inflection point.

[0028] [[ID=二十九]]For confirmation, a device as shown in Fig. 5 was prepared, and an attempt was actually made to grow GeO2 using this two-stage reaction. Here, the Cl2 supply amount in the first stage is 100 ccm, the N2 carrier gas is 400 ccm, the total flow rate of the additional Cl2 line in the second stage is 500 ccm, and growth was carried out with an additional Cl2 flow rate of 80 ccm. The carrier gas for the additional Cl2 line was also N2. The obtained germanium chloride was reacted with O2 in the growth region to grow GeO2 on a supporting crystal substrate. The supply rate of O2 was set to 500 ccm, and the total flow rate of the entire system was adjusted with N2 carrier gas to 5000 ccm. The reaction temperatures for the first and second stages were set to 500°C, and the growth temperature was set to 750°C.

[0029] Under these conditions, the GeO2 crystal obtained after 6 hours of growth had a thickness of 600 μm, so the growth rate was estimated to be 100 μm / h. Furthermore, the surface of the obtained GeO2 crystal was mirror-like, and the macrodefect density was found to be 50 defects / cm². 2 This indicates that, as expected from thermodynamic analysis, the GeCl produced in the first step of the two-step reaction was indeed generated. y It was estimated that (integers y = 1 to 3) could be converted to GeCl4.

[0030] Next, we attempted a growth experiment by reducing the additional Cl2 flow rate from 80 ccm to 50 ccm. The growth rate is 67 μm / h, and the surface macrodefect density is 5000 defects / cm². 2 That was the case. This result occurred because of GeCl y It is thought that the conversion to GeCl4 was insufficient because the additional Cl2 flow rate was insufficient for the conversion of (integers y=1 to 3).

[0031] Next, we attempted a growth experiment by setting the additional Cl2 flow rate to 70 ccm, which is between 80 ccm and 50 ccm. The growth rate is 94 μm / h, and the surface macrodefect density is 100 defects / cm². 2 That was the case.

[0032] Next, we increased the additional Cl2 flow rate to 150 ccm and attempted a growth experiment. The growth rate is 86 μm / h, and the surface macrodefect density is 38 defects / cm². 2 That was the case.

[0033] From the experimental results shown above, GeCl yConvert (integers y=1~3) to GeCl4, and then convert germanium chloride gases other than GeCl4 gas (GeCl y It is thought that the occurrence of macrodefects can be suppressed by minimizing the amount of gas (y = integers from 1 to 3).

[0034] Note that germanium chloride gases other than GeCl4 gas (GeCl y To convert (y=1~3 integer) gas into GeCl4 gas, Cl2 gas or HCl gas can be used as the chlorine source. However, in our experiments, we found that when HCl gas was used as the second chlorine source, the growth rate of GeO2 crystals slowed down. This result is thought to be because HCl gas with a partial pressure equivalent to that of GeCl2 is generated, and then H2 gas with a partial pressure equivalent to that of the added HCl gas is also generated, so the partial pressure of GeCl4 gas does not increase, thus reducing the driving force for GeO2 growth. Therefore, Cl2 gas is suitable as the second additional chlorine source, while HCl gas is not.

[0035] [Method for producing germanium tetrachloride gas] The method for producing germanium tetrachloride gas according to this embodiment comprises a first-stage reaction step and a second-stage reaction step.

[0036] <First stage reaction process> The first reaction step involves reacting metallic germanium with chlorine gas or hydrogen chloride gas to produce germanium chloride gas (GeCl x This is the process of generating integers (x = 1 to 4). The reaction temperature in the first reaction step is preferably 400 to 1000°C, more preferably 500 to 800°C, and even more preferably 600 to 800°C, taking into consideration the reaction rate between metallic germanium and chlorine gas or hydrogen chloride gas. Chlorine gas or hydrogen chloride gas may be supplied together with the carrier gas. Examples of carrier gases include inert gases such as nitrogen gas and argon gas, but nitrogen gas is preferred because it can be easily produced in high purity from the atmosphere, is readily available, and is inexpensive.

[0037] <Second stage reaction process> The second reaction step involves using germanium chloride gas (GeCl) produced in the first reaction step. x This process involves reacting a substance (x = integers from 1 to 3) with chlorine gas to produce germanium tetrachloride gas. The amount of chlorine gas added may be in excess of the stoichiometric amount, but the supply amount (partial pressure) of chlorine gas may be adjusted to the amount of germanium chloride gas (GeCl) produced in the first reaction step. x It is preferable to determine this based on each partial pressure (x = integers from 1 to 4). As a method of this control, it is preferable to allow the amount of Cl2 added to the second stage to be between the amount of Cl2 added to the first stage and four times that amount. It is more preferable that the amount of Cl2 added to the second stage be between the amount of Cl2 added to the first stage and twice that amount, and even more preferable that it be equal to the amount of Cl2 added to the first stage. HCl may be used in the first stage and Cl2 in the second stage. In this case, it is preferable that the amount of Cl2 added in the second stage be between 0.6 and 1.2 times the amount of HCl added in the first stage. It is more preferable that the amount of Cl2 added in the second stage be between 0.6 and 0.9 times the amount of HCl added in the first stage, and even more preferable that it be 0.6 times the amount of HCl added in the first stage.

[0038] The reaction temperature in the second reaction step is GeCl x Considering the reaction rate between the gas (x=1 to 3 integers) and chlorine gas, and given the difficulty in separating temperatures due to furnace size constraints, it is preferable to set the reaction temperature to be the same as the first stage. Therefore, 400 to 1000°C is preferred, 500 to 800°C is more preferred, and 600 to 800°C is even more preferred, but it may be arbitrarily changed within the range of 400 to 1000°C.

[0039] Chlorine gas may be supplied together with a carrier gas. Examples of carrier gases include inert gases such as nitrogen gas and argon gas, but nitrogen gas is preferred because it can be easily produced in high purity from the atmosphere, is readily available, and is inexpensive.

[0040] [Method for producing r-GeO2 single crystals] The method for manufacturing an r-GeO2 single crystal of this embodiment comprises the steps of: producing GeCl4 gas by the germanium tetrachloride gas production method described above; and growing an r-GeO2 single crystal on a supporting crystal substrate by halide vapor phase growth using at least the GeCl4 gas and O2 gas. It is equipped with.

[0041] The reaction temperature between GeCl4 gas and O2 gas in the process of growing r-GeO2 single crystals (GeO2 crystal growth temperature) is preferably 600 to 1000°C, more preferably 700 to 1000°C, and even more preferably 800 to 1000°C. The ratio of GeCl4 gas to O2 gas in the process of growing r-GeO2 single crystals is not particularly limited, but it is preferable that the amount of O2 gas added is greater than the stoichiometric amount in order to make effective use of the GeCl4 gas. O2 gas may be supplied together with a carrier gas. Examples of carrier gases include inert gases such as nitrogen and argon, but nitrogen gas is preferred because it can be easily produced in high purity from the atmosphere, is readily available, and is inexpensive.

[0042] The method for manufacturing an r-GeO2 single crystal according to this embodiment may further include, after the step of growing the r-GeO2 single crystal, a step of cutting off the top surface of the r-GeO2 single crystal, and a step of growing another r-GeO2 single crystal on the cut-out top surface of the r-GeO2 single crystal, and repeating these steps.

[0043] Furthermore, the method for producing r-GeO2 single crystals in this embodiment can achieve a relatively high growth rate for r-GeO2 single crystals. Specifically, the growth rate of the r-GeO2 single crystal is preferably 2 μm / h or higher, more preferably 10 μm / h or higher, and even more preferably 100 μm / h or higher.

[0044] Another embodiment of the method for producing r-GeO2 single crystals involves reacting elemental Ge with Cl2 gas or HCl gas to produce GeCl xIt is also possible to grow r-GeO2 single crystals by generating a mixture of gases (x = integers from 1 to 4) and reacting this germanium chloride gas with H2O.

[0045] [Equipment for manufacturing r-GeO2 single crystals] The r-GeO2 single crystal manufacturing apparatus 1 of this embodiment, whose cross-section is shown in Figure 5, comprises a reaction tube 101, a raw material gas generation unit 102 located inside the reaction tube 101 that generates germanium tetrachloride gas and supplies it onto a support crystal substrate 104, a growth unit 103 located inside the reaction tube 101 that grows an r-GeO2 single crystal on the support crystal substrate 11, a first heating mechanism 111 located outside the reaction tube 101 that heats the raw material gas generation unit 102, and a second heating mechanism 112 located outside the reaction tube 101 that heats the growth unit 103.

[0046] The raw material gas generation unit 102 reacts metallic germanium with chlorine gas or hydrogen chloride gas to produce germanium chloride (GeCl x The first reaction chamber 102a generates gas (x = integers from 1 to 4), and germanium chloride (GeCl y The apparatus includes a second reaction chamber 102b that reacts a gas (integers y=1 to 3) with chlorine gas to produce germanium tetrachloride gas. Piping for supplying chlorine gas or hydrogen chloride gas + carrier gas A is connected to the first reaction chamber 102a. The second reaction chamber 102b is connected to a pipe that supplies germanium chloride gas produced in the first reaction chamber 102a, and to a pipe that supplies chlorine gas + carrier gas B. The chlorine sources supplied to the first reaction chamber 102a and the second reaction chamber 102b can be independently selected from chlorine gas and hydrogen chloride gas, respectively.

[0047] Above the supporting crystal substrate 104, there are pipes for supplying oxygen gas + carrier gas C and pipes for supplying germanium tetrachloride gas from the second reaction chamber 102b.

[0048] Inside the second reaction chamber 102b, germanium chloride (GeCly Baffles 1021, 1022, and 1023 are positioned to promote the mixing of gas (integers y = 1 to 3) and chlorine gas. The shapes of the baffles 1021, 1022, and 1023 include those in which a portion of the plate is provided with a hole through which gas can pass, as shown in Figure 6.

[0049] Since the reaction tube 101 can withstand temperatures of 1000°C or higher, it can be made of, for example, quartz. For example, an electric furnace can be used as the first heating mechanism 111 and the second heating mechanism 112, which are located outside the reaction tube 101. The first heating mechanism 111 is preferably capable of heating to 400 to 1000°C in order to enhance the reactivity between metallic germanium and chlorine gas or hydrogen chloride gas, and between germanium chloride gas and chlorine gas. The second heating mechanism 112 is preferably one that can be heated to 600-1000°C in order to enhance the reactivity between germanium tetrachloride and oxygen gas.

[0050] The supporting crystal substrate 104 can be any type of substrate, such as a sapphire single crystal substrate, an r-TiO2 single crystal substrate, a magnesium oxide substrate, or an r-GeO2 single crystal substrate. If the lattice constant of the supporting crystal substrate 104 and the lattice constant of the r-GeO2 single crystal differ significantly, a buffer layer (intermediate layer) may be formed on the supporting crystal substrate 104, and the r-GeO2 single crystal may be grown on top of it.

[0051] In the growth section 103, the support crystal substrate 104 is placed on the susceptor 1031. The susceptor 1031 is preferably capable of rotating the fixed support crystal substrate 104 to ensure uniform crystal growth on the substrate. Furthermore, when multiple substrates are used, it is preferable that the susceptor 1031 be capable of both rotating and revolving the fixed support crystal substrate 104.

[0052] In this embodiment, the r-GeO2 single crystal manufacturing apparatus 1 determines the partial pressure of chlorine gas supplied to the second reaction chamber 102b based on the partial pressure of chlorine gas or hydrogen chloride gas supplied to the first reaction chamber 102a.

[0053] [Germanium dioxide self-supporting substrate and method for manufacturing the same] The germanium dioxide freestanding substrate of this embodiment is a germanium dioxide freestanding substrate made of an r-GeO2 single crystal, wherein the in-plane concentration of macrodefects appearing on the surface is 5000 defects / cm² in at least a portion of the in-plane area. 2 The following applies: The in-plane concentration of the macrodefects is 1000 defects / cm². 2 The following is preferable: 100 pieces / cm 2 The following is more preferable. The method for evaluating the in-plane concentration of the macrodefects will be described later. The diameter of the germanium dioxide self-supporting substrate in this embodiment is not particularly limited, but is preferably 50 mm or more, more preferably 100 mm or more, and even more preferably 200 mm or more. The thickness of the germanium dioxide freestanding substrate in this embodiment is not particularly limited, but is preferably 200 μm or more and 1 mm or less.

[0054] Furthermore, the germanium dioxide self-supporting substrate of this embodiment can be manufactured by cutting, i.e., slicing and polishing, an r-GeO2 single crystal obtained by the manufacturing method described above.

[0055] [Germanium dioxide template and method for producing the same] The germanium dioxide template of this embodiment is a germanium dioxide template comprising a single-crystal support crystal substrate and a germanium dioxide layer made of an r-GeO2 single crystal epitaxially grown on the support crystal substrate, wherein the in-plane concentration of macrodefects appearing on the side of the germanium dioxide layer opposite to the support crystal substrate is 5000 defects / cm² in at least a portion of the in-plane area. 2 The following applies: The in-plane concentration of the macrodefects is 1000 defects / cm². 2 The following is preferable: 100 pieces / cm 2 The following is more preferable. The method for evaluating the in-plane concentration of the macrodefects will be described later. The diameter of the germanium dioxide template in this embodiment is not particularly limited, but is preferably 50 mm or more, more preferably 100 mm or more, and even more preferably 200 mm or more. The germanium dioxide layer thickness of the germanium dioxide template in this embodiment is not particularly limited, but is preferably 1 μm or more and 200 μm or less.

[0056] The germanium dioxide template of this embodiment can be manufactured by the HVPE method, similar to the method for manufacturing r-GeO2 single crystals described above.

[0057] [Germanium dioxide-based device wafers and methods for manufacturing the same] The germanium dioxide-based device wafer of this embodiment is a germanium dioxide-based device wafer comprising a single-crystal support crystal substrate and a germanium dioxide layer made of an r-GeO2 single crystal epitaxially grown on the support crystal substrate, wherein the in-plane concentration of macrodefects appearing on the wafer surface is 5000 defects / cm² in at least a portion of the in-plane area. 2 The following applies: The in-plane concentration of the macrodefects is 1000 defects / cm². 2 The following is preferable: 100 pieces / cm 2 The following is more preferable. The method for evaluating the in-plane concentration of the macrodefects will be described later. The diameter of the germanium dioxide-based device wafer in this embodiment depends on the diameter of the underlying wafer, but is preferably 50 mm or more, more preferably 100 mm or more, and even more preferably 200 mm or more.

[0058] The germanium dioxide-based device wafer of this embodiment can be manufactured by the HVPE method, similar to the method for manufacturing r-GeO2 single crystals described above.

[0059] Furthermore, as a result of our investigations, we found that, similar to the reaction between elemental Ge and Cl2 or HCl, the reaction between elemental Sn and Cl2 or HCl can also be performed by reacting metallic tin with chlorine gas or hydrogen chloride gas to produce tin chloride gas (SnCl). x After generating x (an integer from 1 to 4), the generated tin chloride gas (SnCly We discovered that by reacting tin (an integer between 1 and 3) with chlorine gas, it is possible to convert it into SnCl4, which prevents the generation of particles caused by the gas-phase reaction between Sn chloride and oxygen. In other words, by reacting metallic tin with chlorine gas or hydrogen chloride gas, tin chloride gas (SnCl) can be converted. x The first-stage reaction step includes a first-stage reaction that produces an integer x (1 to 4), and the tin chloride gas (SnCl) produced. y A second-stage reaction step includes a second-stage reaction in which tin tetrachloride gas is produced by reacting y (an integer from 1 to 3) with chlorine gas.

[0060] [In-plane concentration of macrodefects] In this invention, the in-plane density of macrodefects is evaluated using a microscope. Specifically, the entire wafer surface is inspected using a microscope in a 1 mm square field of view, and the macrodefect density is calculated by dividing the number of detected macrodefects by the wafer area. If macrodefects are present throughout the wafer, the microscope is used to observe nine consecutive 3x3 fields of view in a 1 mm square field of view, and the number of macrodefects contained within each field is calculated using a 9 mm field of view. 2 The result obtained by dividing by this factor is treated as a representative value of the macro-defect density. [Examples]

[0061] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples described later.

[0062] [Comparative Example 1] The manufacturing apparatus shown in Figure 5 is used. The raw material gas generation unit 102 was set to 500°C, and 100 ccm of Cl2 and 400 ccm of N2 carrier gas were supplied to the Ge crystal placed in the first reaction chamber 102a. No Cl2 was supplied to the second reaction chamber 102b, and the germanium chloride generated in the first reaction chamber 102a was passed through it directly. This reacted with 500 ccm of oxygen to grow r-GeO2 to a thickness of 300 μm on an r-TiO2 substrate at a substrate temperature of 750°C. The resulting macrodefect density was approximately 10,000. pieces / cm 2That's what happened. The growth rate of the r-GeO2 crystal was 2 μm / h.

[0063] [Example 1] The raw material gas generation unit 102 was set to 500°C, and 100 ccm of Cl2 and 400 ccm of N2 carrier gas were supplied to the Ge crystal placed in the first reaction chamber 102a. Then, in the second reaction chamber 102b, 400 ccm of N2 and 100 ccm of Cl2 were supplied and reacted before being supplied to the growth unit 103. By reaction with 500 ccm of oxygen, r-GeO2 was grown to a thickness of 300 μm on an r-TiO2 substrate at a substrate temperature of 750°C, resulting in a macrodefect density of 100. pieces / cm 2 As a result, the number decreased dramatically. The growth rate of the r-GeO2 crystal was 100 μm / h. [Explanation of Symbols]

[0064] 1…Equipment for manufacturing r-GeO2 single crystals; 101…Reaction tube; 102... Raw material gas generation unit; 102a... Reaction Chamber 1 102b...Second reaction chamber 1021, 1021a, 1021b, 1021c... Obstruction boards; 103…growth department; 1031... Suscepta; 104…Support crystal substrate; 111...First heating mechanism; 112…Second heating mechanism; A... Chlorine gas or hydrogen chloride gas + carrier gas; B... Chlorine gas + carrier gas; C…Oxygen gas + carrier gas

Claims

1. A rutile-type germanium dioxide self-supporting substrate made of a rutile-type germanium dioxide single crystal, wherein the in-plane concentration of macrodefects appearing on the surface is 0 to 5000 defects / cm² in at least a portion of the in-plane area. ２ A germanium dioxide self-supporting substrate characterized by the following:

2. A method for manufacturing a germanium dioxide self-supporting substrate by halide vapor phase growth, The first step involves placing a support crystal substrate made of a single crystal inside the reaction tube, A second step involves supplying germanium tetrachloride gas and oxygen gas generated in the reaction tube to the support crystal substrate, thereby epitaxially growing a growth crystal consisting of a rutile-type germanium dioxide single crystal on the surface of the support crystal substrate. The process includes a third step of cutting a germanium dioxide self-supporting substrate made of a rutile-type germanium dioxide single crystal from the aforementioned grown crystal, A method for manufacturing a germanium dioxide self-supporting substrate, wherein the second step includes a raw material gas generation step comprising a first-stage reaction in which metallic germanium reacts with chlorine gas or hydrogen chloride gas to produce germanium chloride gas, and a second-stage reaction in which the germanium chloride gas reacts with chlorine gas to produce germanium tetrachloride gas.

3. A method for manufacturing a germanium dioxide self-supporting substrate according to claim 2, wherein the partial pressure of the chlorine gas supplied in the second-stage reaction is determined based on the partial pressure of the chlorine gas or hydrogen chloride gas supplied in the first-stage reaction.

4. A germanium dioxide template comprising a support crystal substrate and a germanium dioxide layer made of a rutile-type germanium dioxide single crystal epitaxially grown on the support crystal substrate, wherein the in-plane concentration of macrodefects appearing on the surface of the germanium dioxide layer opposite to the support crystal substrate is 0 defects / cm² to 5000 defects / cm² in at least a portion of the in-plane area. ２ A germanium dioxide template characterized by the following:

5. A method for producing germanium dioxide templates by halide vapor phase growth, The first step involves placing a support crystal substrate made of a single crystal inside the reaction tube, The process includes a second step of supplying germanium tetrachloride gas and oxygen gas generated in the reaction tube to the support crystal substrate, thereby epitaxially growing a growth crystal made of rutile-type germanium dioxide single crystal on the surface of the support crystal substrate. A method for producing a germanium dioxide template, wherein the second step includes a raw material gas generation step comprising a first-step reaction in which metallic germanium reacts with chlorine gas or hydrogen chloride gas to produce germanium chloride gas, and a second-step reaction in which the germanium chloride gas reacts with chlorine gas to produce germanium tetrachloride gas.

6. The method for producing a germanium dioxide template according to claim 5, wherein the partial pressure of the chlorine gas supplied in the second-stage reaction is determined based on the partial pressure of the chlorine gas or hydrogen chloride gas supplied in the first-stage reaction.

7. A germanium dioxide-based device wafer comprising a support crystal substrate and a germanium dioxide layer made of a rutile-type germanium dioxide single crystal epitaxially grown on the support crystal substrate, wherein the in-plane concentration of macrodefects appearing on the wafer surface is 0 or more and 5000 or more in at least a portion of the in-plane area. ２ A germanium dioxide-based device wafer characterized by the following:

8. A method for manufacturing germanium dioxide-based device wafers by halide vapor phase growth, The first step involves placing a support crystal substrate made of a single crystal inside the reaction tube, The process includes a second step of supplying germanium tetrachloride gas and oxygen gas generated in the reaction tube to the support crystal substrate, thereby epitaxially growing a growth crystal made of rutile-type germanium dioxide single crystal on the surface of the support crystal substrate. A method for manufacturing a germanium dioxide-based device wafer, comprising a second step which includes a raw material gas generation step which includes a first-step reaction in which metallic germanium reacts with chlorine gas or hydrogen chloride gas to produce germanium chloride gas, and a second-step reaction in which the germanium chloride gas reacts with chlorine gas to produce germanium tetrachloride gas.

9. A method for manufacturing a germanium dioxide-based device wafer according to claim 8, wherein the partial pressure of the chlorine gas supplied in the second-stage reaction is determined based on the partial pressure of the chlorine gas or hydrogen chloride gas supplied in the first-stage reaction.

10. Germanium chloride gas (GeCl) is produced by reacting metallic germanium with chlorine gas or hydrogen chloride gas. ｘ A first-stage reaction step includes a first-stage reaction that generates an integer x (1 to 4), The generated germanium chloride gas (GeCl ｙ The second-stage reaction step includes a second-stage reaction in which a substance (y = integers from 1 to 3) is reacted with chlorine gas to produce germanium tetrachloride gas, A method for producing germanium tetrachloride gas, comprising the following components.

11. A method for producing germanium tetrachloride gas according to claim 10, wherein the partial pressure of the chlorine gas supplied in the second-stage reaction step is determined based on the partial pressure of the chlorine gas or hydrogen chloride gas supplied in the first-stage reaction step.

12. A method for producing germanium tetrachloride gas according to claim 11, wherein the first-stage reaction step and the second-stage reaction step are carried out at 400 to 1000°C.

13. GeCl ４ The process of manufacturing gas, at least the GeCl ４ Gas and O ２ A process of growing a rutile-type germanium dioxide single crystal on a supporting crystal substrate using a gas and halide vapor phase epitaxy, A method for producing a rutile-type germanium dioxide single crystal, comprising the features described above.

14. A method for producing a rutile-type germanium dioxide single crystal according to claim 13, wherein the step of growing the rutile-type germanium dioxide single crystal is performed at 600°C or higher.

15. A method for producing a rutile-type germanium dioxide single crystal according to claim 13, further comprising the steps of: after the step of growing the rutile-type germanium dioxide single crystal, cutting off the upper surface of the rutile-type germanium dioxide single crystal; and repeating the step of growing another rutile-type germanium dioxide single crystal on the cut-off upper surface of the rutile-type germanium dioxide single crystal.

16. A reaction tube and A raw material gas generation unit is located inside the reaction tube and generates germanium tetrachloride gas, which is then supplied onto the supporting crystal substrate. A growth section is provided inside the reaction tube for growing a rutile-type germanium dioxide single crystal on the support crystal substrate, A first heating mechanism is located outside the reaction tube and heats the raw material gas generation section, A second heating mechanism is provided, which is located outside the reaction tube and heats the growth section. Equipped with, The raw material gas generation unit reacts metal germanium with chlorine gas or hydrogen chloride gas to produce a germanium chloride (GeCl ｘ , where x is an integer from 1 to 4) gas, and a first reaction chamber for generating Germanium chloride (GeCl ｙ A second reaction chamber in which a gas (y = integers from 1 to 3) and chlorine gas are reacted to produce germanium tetrachloride gas, A manufacturing apparatus for rutile-type germanium dioxide single crystals, equipped with the necessary components.

17. Inside the second reaction chamber, germanium chloride (GeCl ｙ The apparatus for producing a rutile-type germanium dioxide single crystal according to claim 16, wherein a baffle plate is provided to promote the mixing of the gas (y = integers from 1 to 3) and the chlorine gas.

18. In the aforementioned growth portion, GeCl ４ Gas and O ２ An apparatus for producing a rutile-type germanium dioxide single crystal according to claim 16 or 17, wherein a rutile-type germanium dioxide single crystal is formed on the supporting crystal substrate by reaction with a gas.

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