Semi-insulating gallium arsenide single crystal and its manufacturing method and growth apparatus

Abstract

The present application relates to a semi-insulating gallium arsenide single crystal and its manufacturing method and growth device, the manufacturing method of which includes the steps of: putting a crystal raw material into a PBN crucible, moving it into a quartz crucible, placing graphite in a quartz cap, and then sealingly connecting it with the quartz crucible (S1); loading it into a VGF single crystal furnace after sealing and connecting it, and the quartz cap and the quartz crucible are in different temperature zones (S2); and raising the temperature of the temperature zone where the quartz crucible is located to the melting temperature, while simultaneously raising the temperature of the temperature zone where the quartz cap is located to 1000±50°C (S3). The present application discloses a semi-insulating gallium arsenide single crystal and a manufacturing method and growth apparatus thereof, which include steps S3, S4, S5, S6, and S7, in which the temperature zone where the quartz cap is located is controlled to drop to 1000°C±50°C, and the temperature is maintained, doped with the atmosphere, and the crystal is grown. The method of the present application can effectively improve the amount of carbon doping inside the gallium arsenide crystal and the uniformity of the electrical properties.

Description

[Technical Field]

[0001] This application relates to the field of single crystal compounds, and more particularly to semi-insulating gallium arsenide single crystals and methods and growth apparatus for their manufacture. [Background technology]

[0002] Gallium arsenide (GaAs) is the most important material among the second-generation new compound semiconductors following single-crystal silicon. Due to its excellent performance, high electron mobility and photoelectric conversion efficiency, it is widely used in the fields of microelectronics and optoelectronics, and plays an irreplaceable role, especially in the commercialization of 5G.

[0003] Resistivity and mobility are the main performance parameters of semi-insulating gallium arsenide (GaAs) crystals, and the carbon concentration in the crystal has a significant influence on these parameters. In the conventional VGF method for growing semi-insulating gallium arsenide crystals, the carbon doping amount is often controlled by the reaction between high-purity graphite and oxygen released from quartz (produced by the decomposition of quartz and boron oxide), or by the reaction between high-purity graphite and water (trace amounts of water adsorbed by graphite or quartz).

[0004] In the VGF method, graphite and quartz slowly release oxygen at high temperatures, so the increase and diffusion of CO concentration in the atmosphere is very slow. Therefore, there is a gradient difference in the carbon content inside the gallium arsenide crystal, and the difference between the head and tail in the vertical direction inside the crystal is particularly significant. The final product has a resistivity of 10 7 ~10 8 The electrical properties are distributed in the Ω·cm range, resulting in low consistency, which severely limits their commercial use. Summary of the Invention [Problem to be solved by the invention]

[0005] In order to improve the uniformity of carbon concentration in gallium arsenide crystal and its performance such as resistivity and mobility, the present application provides a semi-insulating gallium arsenide single crystal and its manufacturing method and growth apparatus. [Means for solving the problem]

[0006] In a first aspect, the present application provides a semi-insulating gallium arsenide single crystal, the semi-insulating gallium arsenide single crystal having a resistivity of 0.1×10 8 ~5×10 8 Ω·cm, the change in resistivity in the radial direction of the crystal is less than 8%, and the Si concentration is 1.14×10 13 ~4.5×10 15 Atoms·cm -3 and the concentration of C is 6×10 15 ~2.0×10 16 Atoms·cm -3 is.

[0007] This semi-insulating gallium arsenide single crystal has excellent electrical properties such as resistivity and mobility, and the uniformity of its electrical performance is outstanding.

[0008] In a second aspect, the present application provides a method for manufacturing a method of a semiconductor device comprising: S1: Putting GaAs polycrystals, a seed crystal, and boron oxide into a PBN crucible, moving the PBN crucible into a quartz crucible, placing graphite in the quartz cap, and sealing the quartz cap and the quartz crucible together; Step S1 loads the hermetically connected quartz cap and quartz crucible into a VGF single crystal furnace, and the quartz cap and the quartz crucible are in different temperature zones. S2. S3, which controls the temperature zone where the quartz crucible is located so as to increase the temperature to the melting temperature, and simultaneously controls the temperature zone where the quartz cap is located so as to increase the temperature to 1000±50°C; When the temperature zone where the quartz crucible is located reaches the melting temperature, the melting is performed by keeping the temperature, and the temperature zone where the quartz cap is located is controlled so that the temperature is increased to 1200±50°C, and the temperature is kept at 1200±50°C for 4 to 50 hours (S4); After the melting is completed, the temperature of the temperature zone where the quartz cap is located is controlled to drop to 1000°C ± 50°C, and the temperature is maintained, and atmospheric doping is performed to grow crystals (S5); S6, decreasing the temperature and discharging the material.

[0009] The above technical solution provides a new method for controlling the amount of carbon doping. The quartz cap filled with graphite and the quartz crucible are placed in different temperature zones, and the temperature zone where the quartz cap is located is controlled to an appropriate temperature to promote the following reaction between the graphite and the quartz: JPEG0007780223000001.jpg639The CO produced by the reaction provides the main carbon source for atmospheric doping, realizing effective carbon doping of microwave crystals. By controlling the chemical reaction process, the carbon content in the atmosphere can be controlled. Of course, there is also a small amount of CO produced in the atmosphere by the reaction of C with H2O or O2.

[0010] In controlling the above reaction, when the temperature of the temperature zone where graphite is present is ≦1000°C, the reaction between C and SiO2 basically does not proceed, i.e., graphite does not substantially react with quartz to produce CO in steps S3 and S5, but when the temperature of the temperature zone where graphite is present is ≧1200°C, the reaction between C and SiO2 continues, i.e., CO continues to be produced in step S4. The reaction time at temperatures ≧1200°C should be controlled to ensure that the CO content is stable.

[0011] The main pathway for C doping into GaAs is 2Ga + CO → Ga2O + C, The above-mentioned chemical reaction occurs between free Ga in GaAs and CO in the atmosphere, and C is introduced into GaAs.

[0012] On the other hand, in the general VGF process, the carbon source for the atmosphere doping is obtained mainly by the reaction of graphite with moisture and oxygen contained in the growth equipment or the graphite itself, and the reaction formula is as follows: C+H2O→CO+H2, 2C+O2→2CO, C++O2 → CO2, The route by which C is doped into GaAs is as follows: 2Ga+CO→Ga2O+C, 4Ga + CO2 → Ga2O3 + 3C, However, in high-temperature environments, oxygen release from the graphite and the growth apparatus (quartz) is slow, resulting in a low carbon concentration in the crystal and uneven distribution, low crystal resistivity, and large variations in resistivity across regions, resulting in poor application performance. In this application, the reaction rate between C and SiO2 can be controlled by the temperature and the contact area between the graphite and quartz. Generally, the higher the temperature in the temperature zone where the graphite is located, the more vigorously the reaction progresses to the right, resulting in a higher CO content in the ambient space and a higher carbon content in the corresponding crystal. At the same time, the larger the contact area between the graphite and quartz, the higher the CO content in the ambient space and a higher carbon content in the corresponding crystal. This makes it easier to control the CO content in the ambient space, resulting in a more uniform C concentration within the crystal, contributing to improved uniformity in resistivity and mobility within the crystal.

[0013] Preferably, the graphite is pretreated before inserting the quartz cap, and the pretreatment is to remove moisture.

[0014] In the above technical solution, graphite is placed in a quartz container, sealed, and evacuated, and then the quartz container is baked to remove as much moisture as possible from the graphite, reduce the influence of CO concentration in the atmosphere due to CO generated by the reaction of C with HO, improve the accuracy of the carbon doping amount in the crystal, and ensure that the crystal has high resistivity and mobility. In this application, there is no special requirement for the baking temperature, and baking at a temperature of 200±30°C can usually achieve both efficiency and energy consumption.

[0015] Preferably, the PBN crucible, quartz crucible, quartz cap and VGF single crystal furnace are subjected to the above pretreatment before use.

[0016] The PBN crucible, quartz crucible, and quartz cap must be pre-treated before use, and the moisture and oxygen content of the materials and equipment used in crystal growth must be strictly controlled to obtain gallium arsenide crystals with high resistivity.

[0017] Preferably, the vacuum level of the vacuum is (1 to 9 × 10 -4 )~(1~9×10 -2 )Pa.

[0018] By using the above technical solution, it is possible to control sufficient removal of moisture from the graphite raw material at this vacuum level, reduce the occurrence of side reactions between graphite and water, and ensure control of the CO content in the air atmosphere. Generally, a baking time of 2 to 4 hours at this vacuum level will achieve effective removal of moisture.

[0019] Preferably, in step S5, the crystal growth is carried out under conditions where the cooling rate is 0.1 to 10°C / h and the temperature gradient is 0.1 to 10°C / cm.

[0020] The cooling rate and temperature gradient of the above technique effectively ensure the growth of semi-insulating gallium arsenide crystals.

[0021] In a third aspect, the present application provides an apparatus for growing semi-insulating gallium arsenide single crystals, including a VGF single crystal furnace, a quartz crucible located in the VGF single crystal furnace, and a PBN crucible located in the quartz crucible, wherein an opening of the quartz crucible is provided with a quartz cap that covers the opening, and the quartz cap includes a receiving groove for placing graphite therein, and the VGF single crystal furnace is provided with a first temperature zone and a second temperature zone in its axial direction, the quartz cap is located in the first temperature zone, and the quartz crucible is located in the second temperature zone.

[0022] By using the above technical solution, during the crystal growth process, there is a large difference between the temperature field required for crystal growth and the reaction temperature of C and SiO2, so in this application, the quartz tube in which graphite is placed and the quartz crucible in which raw materials such as gallium arsenide are placed are placed in different temperature zones of the VGF single crystal furnace, and the required temperature in each temperature zone is controlled by different heat sources.

[0023] Preferably, the quartz cap has a transition pipe at one end close to the quartz crucible, the transition pipe communicating with the receiving groove.

[0024] Since the graphite reaction temperature and the growth temperature in the quartz crucible are significantly different, a transition pipe is provided between the receiving groove and the quartz crucible to reduce the temperature interference between the two temperature zones, ensuring the reaction between graphite and quartz and contributing to the accurate control of the CO content in the atmosphere.

[0025] Preferably, the diameter of the transition pipe is smaller than the width of the receiving groove.

[0026] By using the above technical solution, the diameter of the transfer pipe is small and the overall shape is elongated, which contributes to reducing the thermal convection between the receiving groove and the quartz crucible and improving the control accuracy of the reaction temperature of the receiving vessel.

[0027] Preferably, the first temperature zone includes a plurality of temperature zones arranged in the axial direction of the VGF single crystal furnace, and the second temperature zone includes a plurality of temperature zones arranged in the axial direction of the VGF single crystal furnace.

[0028] By using the above technical solution, in the improved VGF process of the present application, since a suitable temperature gradient is required for the growth of gallium arsenide crystals, the first temperature zone needs to be divided into multiple independent small temperature zones in the axial direction to form a suitable temperature field and ensure crystal growth; on the other hand, since the reaction between graphite and SiO2 requires a temperature field distinct from the first temperature zone, the second temperature zone also needs to be divided into multiple small temperature zones to ensure accurate control of the reaction temperature.

[0029] In order to achieve effective temperature control, the distance between the current temperature zones is generally controlled to 8cm to 25cm. In this application, the first temperature zone is preferably divided into six smaller temperature zones designated as Tz1 to Tz6, and the second temperature zone is preferably divided into three smaller temperature zones designated as Tz7 to Tz9. [Effects of the Invention]

[0030] In summary, the present application has the following beneficial effects: 1. In this application, the C in the graphite reacts with the SiO2 in the quartz cap to produce CO, which provides the main carbon source for atmospheric doping in the growth of gallium arsenide crystals. This effectively controls the CO content in the atmosphere and ensures uniformity of the carbon doping amount within the crystal, thereby obtaining gallium arsenide single crystals with higher resistivity.

[0031] 2. In this application, the graphite and growth equipment are pretreated to sufficiently reduce their moisture content, which reduces the influence of CO generated by the reaction of graphite with water on the carbon concentration of the crystal, thereby ensuring high crystal resistivity.

[0032] 3. In this application, by setting Tz7 to Tz9 corresponding to the quartz cap, the reaction process between C and SiO2 in the quartz cap can be accurately controlled, effectively ensuring the uniformity of the carbon concentration in the crystal and the uniformity of its internal properties such as resistivity and mobility. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a schematic diagram of a growth apparatus in Example 1 of the present application. [Figure 2] FIG. 2 is a schematic diagram of a growth apparatus in Example 2 of the present application. [Figure 3] FIG. 3 is a graph showing the test results of the element content of the semi-insulating gallium arsenide crystal in Example 1 of the present application. [Figure 4] FIG. 4 is a graph showing the test results of the element content of the semi-insulating gallium arsenide crystal in Example 1 of the present application. [Explanation of symbols]

[0034] 1 VGF single crystal furnace 2 Quartz crucible 3 Quartz Cap 31 Storage groove 32 Transition Pipe 4 PBN crucible 5. First Temperature Zone 6 Second Temperature Zone DETAILED DESCRIPTION OF THE INVENTION

[0035] Manufacturing example Preparation Example 1: Graphite pillars are obtained by pretreatment. The specific procedure of the pretreatment is to place the graphite pillars in a quartz tube, place the quartz tube in an oven, connect it to a vacuum device and seal it, and then evacuate the quartz tube to a vacuum degree of 9×10 -4 Place the quartz tube in an oven and bake at 200 °C for 4 hours to obtain Pa.

[0036] Preparation Example 2: Graphite pillars are obtained by pretreatment. The specific procedure of the pretreatment is to place the graphite pillars in a quartz tube, place the quartz tube in an oven, connect it to a vacuum device and seal it, and then evacuate the quartz tube to a vacuum degree of 1×10 -2 Place the quartz tube in an oven and bake at 220 °C for 2 hours.

[0037] Production Example 3: Graphite pillars, which differ from Production Example 1 in that no pretreatment was performed on the graphite pillars.

[0038] Example Example 1 The present application provides a method for producing semi-insulating gallium arsenide single crystals, in which crystal growth is performed by the VGF method using a semi-insulating gallium arsenide single crystal growth apparatus. Referring to Figure 1, the growth apparatus includes a VGF single crystal furnace 1, a quartz crucible 2 loaded in the VGF single crystal furnace 1, a PBN crucible 4 loaded in the quartz crucible 2, and a quartz cap 3 placed over the opening of the quartz crucible 2. The quartz cap 3 includes a receiving groove 31 in its main body, and a transition pipe 32 communicating with the receiving groove 31 is provided at the bottom of the quartz cap 3, the diameter of the transition pipe 32 being smaller than the width of the receiving groove 31.

[0039] The VGF single crystal furnace 1 includes a first temperature zone 5 provided for the quartz crucible 2 and a second temperature zone 6 provided for the quartz cap 3. Furthermore, the first temperature zone 5 includes Tz1 to Tz6, and the second temperature zone 6 includes Tz7 to Tz9, and Tz1 to Tz9 are provided in order from bottom to top in the axial direction of the VGF single crystal furnace 1, and the temperature of each temperature zone is controlled independently.

[0040] The manufacturing method includes the following steps.

[0041] S1: 10 kg of 7 N GaAs polycrystals, a seed crystal, and 30 g of boron oxide were placed in a 4-inch PBN crucible 4. The PBN crucible 4 was then moved into a quartz crucible 2 to complete the filling. A graphite pillar (manufactured in Manufacturing Example 1) with a diameter of 50 mm and a thickness (length) of 20 mm was then placed in the accommodation groove 31 in the quartz cap 3, with the circular bottom of the graphite pillar in contact with the accommodation groove 31. The quartz cap 3 and the quartz crucible 2 were then hermetically connected (welded).

[0042] S2: The quartz cap 3 and the quartz crucible 2 that were hermetically connected in step S1 are loaded into the VGF single crystal furnace 1, and the quartz cap 3 is located at Tz7 to Tz9 of the VGF single crystal furnace 1, and the quartz crucible 2 is located at Tz1 to Tz6 of the VGF single crystal furnace 1.

[0043] S3: Control Tz1 to Tz6 so that the temperatures are increased to 1238°C (melting temperature), and simultaneously control Tz7 to Tz9 so that the temperatures are increased to 1000±50°C.

[0044] S4: When Tz1 to Tz6 reach 1238°C (melting temperature), they are kept at the same temperature for 6 to 12 hours until they are melted. At the same time, the temperatures of Tz7 to Tz9 are controlled to rise to 1200±50°C in 30 minutes, and then kept at the same temperature for 10 hours.

[0045] S5: After the GaAs polycrystal is melted, the crystal is grown using the VGF method. The cooling rate in Tz1 to Tz6 is 2 to 6°C / h, and the temperature gradient is 0.1 to 5°C / cm. At the same time, the temperature in the temperature zones Tz7 to Tz9 is controlled to drop to 1000°C ± 50°C in 1 hour. The temperature is kept constant to ensure that the graphite and quartz react with each other, and a stable CO atmosphere is formed.

[0046] S6: The temperature is lowered and the material is discharged. Here, when Tz1 to Tz6 are in the range of 1200 to 1238°C, the temperature drop rate is 2±1°C / h; when they are in the range of 1000 to 1200°C, the temperature drop rate is 5 to 15°C / h; when they are in the range of 50 to 1000°C, the temperature drop rate is 30±10°C / h. During this process, Tz7 to Tz9 are gradually lowered to the discharge temperature, and finally a semi-insulating gallium arsenide crystal 200 mm long is obtained.

[0047] According to the test method specified in SJ / T11488-2015, the resistivity and mobility of the above-prepared crystal were tested, and the test results are shown below. JPEG0007780223000002.jpg47147

[0048] Radial resistance change rate within the crystal (difference from average resistance value) = (test point resistance value / average value of test sheet) x 100%

[0049] The resistance ratio value of the crystal head to tail: head average value / tail average value=0.97.

[0050] The test results for element content are shown in Figure 3.

[0051] As can be seen from FIG. 3, the Si content is 1.14×10 13 ~4.5×10 15 Atoms·cm -3 and the C content is between 6 x 10 15 ~2.0×10 16 Atoms·cm -3 It is between.

[0052] Example 2 The present application provides a method for producing semi-insulating gallium arsenide single crystals, in which a semi-insulating gallium arsenide single crystal growth apparatus is used to grow crystals by the VGF method. Referring to Figure 2, the growth apparatus includes a VGF single crystal furnace 1, a quartz crucible 2 is loaded in the VGF single crystal furnace 1, a PBN crucible 4 is loaded in the quartz crucible 2, and a quartz cap 3 is placed over the opening of the quartz crucible 2. The main body of the quartz cap 3 includes a receiving groove 31, and the bottom of the quartz cap 3 is provided with a transition pipe 32 communicating with the receiving groove 31, the diameter of the transition pipe 32 being smaller than the width of the receiving groove 31.

[0053] The VGF single crystal furnace 1 includes a first temperature zone 5 provided for the quartz crucible 2 and a second temperature zone 6 provided for the quartz cap 3. Furthermore, the first temperature zone 5 includes Tz1 to Tz6, and the second temperature zone 6 includes Tz7 to Tz9, and Tz1 to Tz9 are provided in order from bottom to top in the axial direction of the VGF single crystal furnace 1, and the temperature of each temperature zone is controlled independently.

[0054] The manufacturing method includes the following steps. S1: 24 kg of 7 N GaAs polycrystals, a seed crystal, and 65 g of boron oxide were placed in a 6-inch PBN crucible 4. The PBN crucible 4 was then moved into a quartz crucible 2 to complete the filling. A graphite pillar (manufactured in Manufacturing Example 2) with a diameter of 60 mm and a thickness (length) of 20 mm was then placed in the groove 31 in the quartz cap 3, with the circular bottom of the graphite pillar in contact with the groove 31. The quartz cap 3 and the quartz crucible 2 were then hermetically connected.

[0055] S2: The quartz cap 3 and the quartz crucible 2 that were hermetically connected in step S1 are loaded into the VGF single crystal furnace 1, and the quartz cap 3 is located at Tz7 to Tz9 of the VGF single crystal furnace 1, and the quartz crucible 2 is located at Tz1 to Tz6 of the VGF single crystal furnace 1.

[0056] S3: Control Tz1 to Tz6 so that the temperatures are increased to 1238°C (melting temperature), and simultaneously control Tz7 to Tz9 so that the temperatures are increased to 1000±50°C.

[0057] S4: When Tz1 to Tz6 reach 1238°C (melting temperature), they are kept at the same temperature for 6 to 10 hours until they are melted. At the same time, the temperatures of Tz7 to Tz9 are controlled to rise to 1200±50°C in 30 minutes, and then kept at the same temperature for 50 hours.

[0058] S5: After the GaAs polycrystal is melted, the crystal is grown using the VGF method. The cooling rate of Tz1 to Tz6 is 5 to 10°C / h, and the temperature gradient is 3 to 8°C / cm. At the same time, the temperature is controlled to drop to 1000°C ± 50°C in 1 hour for Tz7 to Tz9. The temperature is kept constant to ensure that the graphite and quartz react with each other, and a stable CO atmosphere is formed.

[0059] S6: The temperature is lowered and the material is discharged. Here, when Tz1 to Tz6 are in the range of 1200 to 1238°C, the temperature drop rate is 2±1°C / h; when they are in the range of 1000 to 1200°C, the temperature drop rate is 5 to 15°C / h; when they are in the range of 50 to 1000°C, the temperature drop rate is 30±10°C / h. During this process, Tz7 to Tz9 are gradually lowered to the discharge temperature, and finally a semi-insulating gallium arsenide crystal 200 mm long is obtained.

[0060] According to the test method specified in SJ / T11488-2015, the resistivity and mobility of the above-prepared crystal were tested, and the test results are shown below. JPEG0007780223000003.jpg70147

[0061] Radial resistance change rate within the crystal = (test point resistance value / average value of test sheet) x 100%

[0062] The resistance ratio value of the crystal head to tail: head average value / tail average value=0.72.

[0063] The test results for element content are shown in Figure 4.

[0064] As can be seen from FIG. 4, the Si content is 1.14×10 13 ~4.5×10 15 Atoms·cm -3 and the C content is between 6 x 10 15 ~2.0×10 16 Atoms·cm -3 It is between.

[0065] Example 3 This application discloses a method for manufacturing a semi-insulating gallium arsenide single crystal, and the difference between this method and Example 1 is that the manufacturing process is as follows:

[0066] S1: 10 kg of 7 N GaAs polycrystals, a seed crystal, and 30 g of boron oxide were placed in a 4-inch PBN crucible 4. The PBN crucible 4 was then moved into a quartz crucible 2 to complete the filling. A graphite pillar (manufactured in Manufacturing Example 1) with a diameter of 50 mm and a thickness of 20 mm was then placed in the groove 31 in the quartz cap 3, with the circular bottom of the graphite pillar in contact with the groove 31. The quartz cap 3 and the quartz crucible 2 were then hermetically connected.

[0067] S2: The quartz cap 3 and the quartz crucible 2 that were hermetically connected in step S1 are loaded into the VGF single crystal furnace 1, and the quartz cap 3 is located at Tz7 to Tz9 of the VGF single crystal furnace 1, and the quartz crucible 2 is located at Tz1 to Tz6 of the VGF single crystal furnace 1.

[0068] S3: Control Tz1 to Tz6 so that the temperatures are increased to 1238°C (melting temperature), and simultaneously control Tz7 to Tz9 so that the temperatures are increased to 1000±50°C.

[0069] S4: When Tz1 to Tz6 reach 1238°C (melting temperature), they are kept at the same temperature for 6 to 12 hours until they are melted. At the same time, the temperatures of Tz7 to Tz9 are controlled to rise to 1200±50°C in 30 minutes, and then kept at the same temperature for 4 hours.

[0070] S5: After the GaAs polycrystal is melted, the crystal is grown using the VGF method. The cooling rate of Tz1 to Tz6 is 0.1 to 5°C / h, and the temperature gradient is 2 to 7°C / cm. At the same time, the temperature of Tz7 to Tz9 is controlled to drop to 1000°C ± 50°C in 1 hour. The temperature is kept constant to ensure that the graphite and quartz react with each other, and a stable CO atmosphere is formed.

[0071] S6: The temperature is lowered and the material is discharged. Here, when Tz1 to Tz6 are in the range of 1200 to 1238°C, the temperature drop rate is 2±1°C / h; when they are in the range of 1000 to 1200°C, the temperature drop rate is 5 to 15°C / h; when they are in the range of 50 to 1000°C, the temperature drop rate is 30±10°C / h. During this process, Tz7 to Tz9 are gradually lowered to the discharge temperature, and finally a semi-insulating gallium arsenide crystal 200 mm long is obtained.

[0072] According to the test method specified in SJ / T11488-2015, the resistivity and mobility of the above-prepared crystal were tested, and the test results are shown below. JPEG0007780223000004.jpg47147

[0073] The resistance ratio value of the crystal head to tail: head average value / tail average value=0.65.

[0074] Example 4 This application discloses a method for producing semi-insulating gallium arsenide single crystals, and the difference from Example 1 is that the graphite pillars produced in Example 3 are used in step S1.

[0075] The resistivity and mobility of the above-produced crystals were tested according to the test method specified in SJ / T11488-2015. The test results showed that the parameter consistency of crystals from the same batch was low due to the lack of treatment for graphite moisture, and the resistivity of crystals obtained under the same process environment was 1×10 8 Ω·cm or 5×10 8 Even if the crystal parameters are inappropriate and cannot be measured, a single crystal will have good consistency in the parameters, indicating the presence of a normal crystal.

[0076] Example 5: A method for manufacturing a semi-insulating gallium arsenide single crystal, which differs from Example 1 in that the manufacturing process is as follows.

[0077] S1: 10 kg of 7 N GaAs polycrystals, a seed crystal, and 30 g of boron oxide were placed in a 4-inch PBN crucible 4. The PBN crucible 4 was then moved into a quartz crucible 2 to complete the filling. A graphite pillar (manufactured in Manufacturing Example 1) with a diameter of 30 mm and a thickness (length) of 20 mm was then placed in the accommodation groove 31 in the quartz cap 3, with the circular bottom of the graphite pillar in contact with the graphite groove 31. The quartz cap 3 and the quartz crucible 2 were then hermetically connected.

[0078] S2: The quartz cap 3 and the quartz crucible 2 that were hermetically connected in step S1 are loaded into the VGF single crystal furnace 1, and the quartz cap 3 is located at Tz7 to Tz9 of the VGF single crystal furnace 1, and the quartz crucible 2 is located at Tz1 to Tz6 of the VGF single crystal furnace 1.

[0079] S3: Control Tz1 to Tz6 so that the temperatures are increased to 1238°C (melting temperature), and simultaneously control Tz7 to Tz9 so that the temperatures are increased to 1000±50°C. S4: When Tz1 to Tz6 reach 1238°C (melting temperature), they are kept at the same temperature for 6 to 12 hours until they are melted. At the same time, the temperatures of Tz7 to Tz9 are controlled to rise to 1200±50°C in 30 minutes and kept at the same temperature for 6 hours.

[0080] S5: After the GaAs polycrystal is melted, the crystal is grown using the VGF method. The cooling rate of Tz1 to Tz6 is 2 to 6°C / h, and the temperature gradient is 0.1 to 5°C / cm. At the same time, the temperature of Tz7 to Tz9 is controlled to drop to 1000°C ± 50°C in 1 hour. The temperature is kept constant to ensure that the graphite and quartz react with each other, and a stable CO atmosphere is formed.

[0081] S6: The temperature is lowered and the material is discharged. Here, when Tz1 to Tz6 are in the range of 1200 to 1238°C, the temperature drop rate is 1 to 3°C / h; when they are in the range of 1000 to 1200°C, the temperature drop rate is 5 to 15°C / h; when they are in the range of 50 to 1000°C, the temperature drop rate is 20 to 40°C / h; during this process, Tz7 to Tz9 are gradually lowered to the discharge temperature, and finally a semi-insulating gallium arsenide crystal 200 mm long is obtained.

[0082] According to the test method specified in SJ / T11488-2015, the resistivity and mobility of the above-prepared crystal were tested, and the test results are shown below. JPEG0007780223000005.jpg47147

[0083] The resistance ratio value of the crystal head to tail: head average value / tail average value=0.78.

[0084] Comparative Example Comparative Example 1 The present application provides a method for producing semi-insulating gallium arsenide single crystals, in which crystal growth is performed using a semi-insulating gallium arsenide single crystal growth apparatus by the VGF method. The growth apparatus includes a VGF single crystal furnace 1, in which a quartz crucible 2 and a quartz cap 3 are loaded. The quartz cap 3 is provided with a receiving groove 31, and the height of the receiving groove 31 is smaller than the depth of the quartz cap 3.

[0085] The VGF single crystal furnace 1 is provided with temperature zones Tz1 to Tz6 in the axial direction, each of which is provided with an independent heat source, and the quartz crucible 2 and quartz cap 3 are both within the ranges of Tz1 to Tz6.

[0086] The manufacturing method includes the following steps. S1: 10 kg of 7 N GaAs polycrystals, a seed crystal, and 30 g of boron oxide are placed in a 4-inch PBN crucible 4. The PBN crucible 4 is then moved into a quartz crucible 2 to complete the filling. A graphite pillar with a diameter of 50 mm and a thickness of 20 mm is then placed in the groove 31 in the quartz cap 3, and the quartz cap 3 and the quartz crucible 2 are hermetically connected.

[0087] S2: The quartz cap 3 and the quartz crucible 2 that have been hermetically connected in step S1 are loaded into the VGF single crystal furnace 1.

[0088] S3: Control Tz1 to Tz6 so that the temperature rises to 1238°C (melting temperature).

[0089] S4: When Tz1 to Tz6 reach 1238°C (melting temperature), they are kept at that temperature for 6 to 10 hours until they are melted.

[0090] S5: After the GaAs polycrystal is melted, the crystal is grown using the VGF method, and the cooling rate of Tz1 to Tz6 is 1 to 5 °C / h and the temperature gradient is 2 to 6 °C / cm.

[0091] S6: The temperature is decreased and the material is discharged. When Tz1 to Tz6 are in the range of 1200 to 1238°C, the temperature decrease rate is 2±1°C / h; when they are in the range of 1000 to 1200°C, the temperature decrease rate is 5 to 15°C / h; when they are in the range of 50 to 1000°C, the temperature decrease rate is 30±10°C / h; and finally, a semi-insulating gallium arsenide crystal with a length of 200 mm is obtained.

[0092] According to the test method specified in SJ / T11488-2015, the resistivity and mobility of the above-prepared crystal were tested, and the test results are shown below. JPEG0007780223000006.jpg64147

[0093] As can be seen from the table above, the data of the crystal tail is anti-type, it is a P-type semiconductor crystal, and the high resistance hole cannot be measured, showing 105.

[0094] Comparative Example 2 The present application provides a method for producing semi-insulating gallium arsenide single crystals, and the difference between this method and Comparative Example 1 is that crystal growth is performed using the growth apparatus for semi-insulating gallium arsenide single crystals in Example 1, and the temperatures Tz7 to Tz9 are controlled to always be within the range of 1200±50°C.

[0095] The specific manufacturing process is as follows. S1: 10 kg of 7 N GaAs polycrystals, a seed crystal, and 30 g of boron oxide were placed in a 4-inch PBN crucible 4. The PBN crucible 4 was then moved into a quartz crucible 2 to complete the filling. A graphite pillar (manufactured in Manufacturing Example 1) with a diameter of 50 mm and a thickness (length) of 20 mm was then placed in the groove 31 in the quartz cap 3, with the circular bottom of the graphite pillar in contact with the groove 31. The quartz cap 3 and the quartz crucible 2 were then hermetically connected.

[0096] S2: The quartz cap 3 and the quartz crucible 2 that were hermetically connected in step S1 are loaded into the VGF single crystal furnace 1, and the quartz cap 3 is located at Tz7 to Tz9 of the VGF single crystal furnace 1, and the quartz crucible 2 is located at Tz1 to Tz6 of the VGF single crystal furnace 1.

[0097] S3: Control Tz1 to Tz6 so that the temperatures are increased to 1238°C (melting temperature), and simultaneously control Tz7 to Tz9 so that the temperatures are increased to 1200±50°C.

[0098] S4: When Tz1 to Tz6 reach 1238°C (melting temperature), they are kept at that temperature for 8 hours to melt, and at the same time, the temperatures of Tz7 to Tz9 are controlled to rise to 1200±50°C.

[0099] S5: After the GaAs polycrystal is melted, the crystal is grown using the VGF method. The cooling rate of Tz1 to Tz6 is 2 to 6°C / h, and the temperature gradient is 0.1 to 5°C / cm. At the same time, the temperature of Tz7 to Tz9 is controlled to be 1200°C ± 50°C, ensuring that the graphite and quartz react with each other and forming a CO atmosphere with a stable content.

[0100] S6: The temperature is lowered and the material is discharged. Here, when Tz1 to Tz6 are in the range of 1200 to 1238°C, the temperature drop rate is 2±1°C / h; when they are in the range of 1000 to 1200°C, the temperature drop rate is 5 to 15°C / h; when they are in the range of 50 to 1000°C, the temperature drop rate is 30±10°C / h. During this process, Tz7 to Tz9 are gradually lowered to the discharge temperature, and finally a semi-insulating gallium arsenide crystal 200 mm long is obtained.

[0101] According to the test method specified in SJ / T11488-2015, the resistivity and mobility of the above-prepared crystal were tested, and the test results are shown below. JPEG0007780223000007.jpg64147

[0102] As can be seen from the table above, the data of the crystal tail is anti-type, it is a P-type semiconductor crystal, and the high resistance hole cannot be measured, showing 105.

[0103] Analysis of test results: (1) As can be seen from Examples 1 to 5 and Comparative Examples 1 and 2, in Examples 1 to 5, the quartz crucibles in which graphite and gallium arsenide crystals are grown are located in different temperature zones, and carbon doping of semi-insulating gallium arsenide is achieved by controlling the temperature of the temperature zone in which graphite is located to reach an appropriate reaction temperature, while in Comparative Example 1, semi-insulating gallium arsenide is grown using a conventional VGF method. The test results show that, compared with Comparative Example 1, the resistivities of the crystals obtained in Examples 1 to 5 are significantly more uniformly distributed, and the crystal head-to-tail resistance ratios are smaller.

[0104] The reason for this is thought to be that in this application, the CO content in the space atmosphere is JPEG0007780223000008.jpg639 is controlled by the reaction. The higher the reaction temperature, the more the reaction shifts to the right. The longer the reaction time, the higher the CO content in the ambient atmosphere. At the same time, the larger the contact area between the graphite (C) and the quartz tube (SiO2), the higher the CO content. This reaction process is easy to control and can rapidly generate CO gas in the growth apparatus, thereby making the CO content at each location in the growth apparatus relatively uniform and further ensuring the uniformity of the carbon doping amount in the gallium arsenide crystal. Meanwhile, in Comparative Example 1, the CO content in the ambient atmosphere is mainly controlled by reactions between graphite and water, oxygen released from the quartz cap (generating the quartz cap and boron oxide), or graphite and water (generating the graphite or quartz cap). Because the oxygen release rate is slow in a high-temperature environment, the increase and diffusion of CO content in the atmosphere is very slow, and the grown gallium arsenide crystal has low uniformity in its internal carbon content, which results in differences in its electrical properties.

[0105] In Comparative Example 2, Tz7 to Tz9 are always at a high temperature of 1200±50°C, and the graphite and quartz are always in contact with each other. JPEG0007780223000009.jpg639As the reaction continues to run and CO is continuously produced, the carbon content of the crystal changes rapidly, causing large changes in crystal parameters of over 8%, making it difficult to control the final resistivity and mobility of the product.

[0106] The specific examples are merely illustrative of the present application and do not limit the present application. After reading this specification, a person skilled in the art may make amendments to the examples as necessary without making any creative contribution, but all such amendments within the scope of the claims of the present application shall be protected by the Patent Law.

Claims

1. A method for producing a semi-insulating gallium arsenide single crystal, comprising: S1: placing GaAs polycrystals, a seed crystal, and boron oxide in a PBN crucible, moving the PBN crucible into a quartz crucible, placing graphite in a quartz cap, and hermetically connecting the quartz cap and the quartz crucible; Step S1: Loading the quartz cap and the quartz crucible hermetically connected in step S1 into a VGF single crystal furnace, and the quartz cap and the quartz crucible are in different temperature zones; S3: controlling the temperature zone where the quartz crucible is located so as to increase the temperature to the melting temperature, and simultaneously controlling the temperature zone where the quartz cap is located so as to increase the temperature to 1000±50°C; When the temperature zone where the quartz crucible is located reaches the melting temperature, the melting is performed by keeping the temperature, and the temperature zone where the quartz cap is located is controlled so that the temperature is increased to 1200±50°C, and the temperature is kept at 1200±50°C for 4 to 50 hours (S4); After the melting is completed, the temperature of the temperature zone where the quartz cap is located is controlled to drop to 1000°C ± 50°C, and the temperature is maintained, and atmospheric doping is performed to grow a crystal (S5); S6, decreasing the temperature and discharging the material.

2. 2. The method for producing a semi-insulating gallium arsenide single crystal according to claim 1, wherein the graphite is pretreated before the quartz cap is inserted, and the pretreatment is to remove moisture.

3. 3. The method for producing semi-insulating gallium arsenide single crystals according to claim 2, wherein the PBN crucible (4), the quartz crucible (2), the quartz cap (3) and the VGF single crystal furnace (1) are subjected to the pretreatment before use.

4. The pretreatment includes a vacuum evacuation operation, and the absolute vacuum of the vacuum evacuation operation is (1 to 9×10 －４ ) to (1 to 9 x 10 －２ 3. The method for producing a semi-insulating gallium arsenide single crystal according to claim 2, wherein the gallium arsenide single crystal is 0.1 Pa.

5. 2. The method for producing a semi-insulating gallium arsenide single crystal according to claim 1, wherein in step S5, the crystal growth is performed under conditions of a cooling rate of 0.1 to 10 ° C / h and a temperature gradient of 0.1 to 10 ° C / cm.

6. The method is used to obtain a semi-insulating gallium arsenide single crystal, and the resistivity of the semi-insulating gallium arsenide single crystal is 0.1×10 ８ ~5 x 10 ８ Ω cm, the change in resistivity in the radial direction of the crystal is less than 8%, and the Si concentration is 1.14×10 １３ ~4.5 x 10 １５ Atoms・cm －３ and the concentration of C is 6×10 １５ ~2.0 x 10 １６ Atoms・cm －３ 2. The method for producing a semi-insulating gallium arsenide single crystal according to claim 1, wherein

7. 1. An apparatus for growing semi-insulating gallium arsenide single crystals, comprising:

7. The method for producing a semi-insulating gallium arsenide single crystal according to claim 1, wherein the growth apparatus includes a VGF single crystal furnace (1), a quartz crucible (2) located in the VGF single crystal furnace (1), and a PBN crucible (4) provided in the quartz crucible (2), wherein a quartz cap (3) is provided to cover the opening of the quartz crucible (2), and the quartz cap (3) includes a receiving groove (31) for placing graphite therein, and the VGF single crystal furnace (1) is provided with a first temperature zone (5) and a second temperature zone (6) in its axial direction, the quartz cap (3) is located in the second temperature zone (6), and the quartz crucible (2) is located in the first temperature zone (5).

8. 8. The apparatus for growing semi-insulating gallium arsenide single crystals according to claim 7, wherein the quartz cap (3) is provided with a transition pipe (32) at one end close to the quartz crucible (2), and the transition pipe (32) communicates with the receiving groove (31).

9. 9. The apparatus for growing semi-insulating gallium arsenide single crystals according to claim 8, wherein the diameter of the transition tube (32) is smaller than the width of the receiving groove (31).

10. 8. The apparatus for growing semi-insulating gallium arsenide single crystals according to claim 7, wherein the first temperature zone (5) comprises a plurality of temperature zones arranged in the axial direction of the VGF single crystal furnace (1), and the second temperature zone (6) comprises a plurality of temperature zones arranged in the axial direction of the VGF single crystal furnace (1).

Images