A method for synthesizing indium phosphide polycrystals

Abstract

A method for synthesizing indium phosphide polycrystals belongs to the field of semiconductor technology and includes the following steps: heating indium in a crucible to form a melt; opening a condenser; heating and vaporizing phosphorus, wherein the vaporized phosphorus vapor enters the melt in the crucible and reacts with indium to form indium phosphide; the phosphorus vapor overflowing the melt exchanges heat with the condenser, condenses into droplets, and flows into a liquid phosphorus delivery pipe; when the liquid phosphorus level in the liquid phosphorus delivery pipe gradually increases to a certain height, the seal is opened, and the liquid phosphorus flows into a quartz phosphorus container; after the reaction is completed, the heater and the phosphorus heater are stopped, the temperature is cooled to room temperature, the device is disassembled, and the crucible is removed. The present invention utilizes condensation technology to recover the escaped phosphorus vapor and allow it to continue participating in the reaction, thereby greatly improving the utilization rate of raw materials, increasing the amount of polycrystals synthesized in a single batch, and significantly improving the synthesis efficiency; the escaped phosphorus vapor is recycled, eliminating the tedious furnace cleaning process; and it is possible to achieve a single phosphorus loading and multiple indium phosphide synthesizations.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors and relates to the preparation of indium phosphide polycrystals. Background Art

[0002] Indium phosphide (InP) is a III-V compound semiconductor material with a direct band gap, high electron mobility, radiation resistance, and high thermal conductivity. It holds a strategically important position in the semiconductor materials field and is an irreplaceable semiconductor material for optoelectronic and microelectronic devices. With advances in band engineering theory, ultra-thin material processing technology, and deep submicron manufacturing techniques, InP has become the material of choice for high-end microwave, millimeter-wave electronics, and optoelectronic devices.

[0003] High-purity, inclusion-free InP polycrystalline materials with varying melt proportions are prerequisites for producing high-quality InP and conducting research on its properties. Many properties of InP crystals are related to the characteristics of the starting material, the polycrystalline material, such as its proportion and purity. These properties significantly influence crystal growth, electrical performance, integrity, and uniformity. Therefore, rapid, high-volume synthesis of InP melts is a highly sought-after issue in InP research.

[0004] Indium phosphide polycrystals are composed of the Group III element indium (In) and the Group V element phosphorus (P). Currently, the commonly used methods for synthesizing InP polycrystals include the horizontal Bridgman method (HB), horizontal gradient solidification method (HGF), and phosphorus injection method. The synthesis of InP materials using the horizontal Bridgman method (HB) and horizontal gradient solidification method (HGF) requires a longer synthesis time as the synthesis volume increases. Generally, it takes about 24 hours to synthesize 1.5 kg of InP polycrystals using HB / HGF technology. As a result, Si contamination is more pronounced (the source is the quartz tube wall). The lowest carrier concentration of industrially available InP polycrystals is 6×1015 cm -3 This has adverse effects on the preparation of high-performance microelectronic devices and optoelectronic devices, and the possibility of "tube explosion" is also high. Regardless of the form of synthesis boat, it is very difficult to increase the weight of In, and increasing the diameter of the quartz tube will inevitably require a larger-caliber autoclave, and the cost will also increase rapidly. The phosphorus injection synthesis technology is to inject vaporized phosphorus vapor into the indium melt to synthesize the indium phosphide melt. Since this method relies on the internal and external pressure difference of the quartz phosphorus container to inject phosphorus vapor, if the pressure difference is not properly controlled, it is easy to cause bubbles to explode; on the other hand, some phosphorus vapor is not absorbed by the indium melt, which affects the synthesis effect on the one hand, and the lost phosphorus vapor evaporates into the furnace body on the other hand, causing great trouble for furnace cleaning.

[0005] Regardless of the method used, the amount of phosphorus and indium needs to be calculated accurately before synthesis to avoid incomplete reaction or waste of materials. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for synthesizing an indium phosphide polycrystalline material, which adopts a condensation technology to recover the escaped phosphorus vapor and then continue to participate in the reaction.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for synthesizing indium phosphide polycrystals, implemented based on an indium phosphide synthesis device with a phosphorus recovery device, the indium phosphide synthesis device comprising a quartz phosphorus container disposed at the bottom, a phosphorus heater disposed around the quartz phosphorus container, a crucible connected to the quartz phosphorus container, and a heater disposed around the crucible. The key feature is that: micron-sized holes are disposed at the bottom of the crucible. The indium phosphide synthesis device also includes a phosphorus recovery device, including a condenser located above the crucible, a liquid phosphorus channel disposed opposite the condenser 6, and a liquid phosphorus delivery pipe at the end of the liquid phosphorus channel. The liquid phosphorus delivery pipe connects the space near the condenser and the quartz phosphorus container, and a plug is provided at the bottom opening of the liquid phosphorus delivery pipe.

[0008] The method comprises the following steps:

[0009] 1.1. Loading indium: Clean and dry the surface of indium and load it into the crucible;

[0010] 1.2. Phosphorus loading: put red phosphorus into quartz phosphorus container;

[0011] 1.3. Assembly: Assemble the crucible and quartz phosphorus container together;

[0012] 1.4. Synthesis:

[0013] 1.4.1. Heat the indium in the crucible until it melts and forms a melt;

[0014] 1.4.2. Open the condenser and introduce circulating coolant;

[0015] 1.4.3. The phosphorus in the quartz phosphorus container is heated and vaporized. The vaporized phosphorus vapor enters the melt in the crucible through the micron-sized holes (10) at the bottom of the crucible and reacts with indium to form indium phosphide;

[0016] 1.4.4. The phosphorus vapor overflowing from the melt exchanges heat with the condenser, condenses into liquid droplets, and flows into the liquid phosphorus delivery pipe;

[0017] 1.4.5. The liquid phosphorus level in the liquid phosphorus delivery pipe gradually increases. When it reaches a certain height, the seal is opened due to the pressure of the liquid phosphorus, and the liquid phosphorus flows into the quartz phosphorus container;

[0018] 1.4.6. After the reaction is completed, stop the heater and phosphorus heater, cool to room temperature, disassemble the device, and remove the crucible.

[0019] Furthermore: in step 1.4.1, the heating temperature is 10-20°C higher than the melting point of indium; in step 1.4.3, the heating temperature is 10-20°C higher than the melting point of indium phosphide.

[0020] Furthermore: in step 1.4.6, first stop the heater, and after the melt solidifies, stop the phosphorus heater.

[0021] The present invention liquefies the gasified phosphorus vapor that is not absorbed into white phosphorus through a condenser and flows into a phosphorus delivery pipe. When the liquid phosphorus reaches a certain amount, the liquid phosphorus flows into a crucible and is heated to be gasified again to participate in the reaction.

[0022] Beneficial effects: The present invention uses condensation technology to recover the escaped phosphorus vapor and continue to participate in the reaction, which greatly improves the utilization rate of raw materials, saves costs, and improves economic benefits; increases the synthesis amount of single polycrystals and greatly improves the synthesis efficiency; the escaped phosphorus vapor is recovered and reused, eliminating the tedious furnace cleaning process; and can achieve one-time phosphorus loading and multiple synthesis of indium phosphide without having to calculate the phosphorus-indium ratio for filling each time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the equipment composition diagram of the quartz phosphorus container and phosphorus recovery device.

[0024] Figure 2 is a schematic diagram of the crucible structure.

[0025] Figure 3 This is a schematic diagram of the equipment after assembly.

[0026] Figure 4 is the state diagram of the equipment during the synthesis process,

[0027] Figure 5 This is the status diagram of the device when the blockage is opened.

[0028] Figure 6 Schematic diagram of the partition.

[0029] Among them, 1 is a phosphorus heater, 2 is red phosphorus, 3 is a quartz phosphorus container, 4 is a seal, 5 is a liquid phosphorus delivery pipe, 6 is a condenser, 7 is indium, 8 is a crucible, 9 is a heater, 10 is a micron-sized hole, 11 is a liquid phosphorus heater, 12 is liquid phosphorus, 13 is an inclined channel, 14 is a sealing groove, 15 is a sealing strip, and 16 is a partition. DETAILED DESCRIPTION

[0030] A method for synthesizing indium phosphide polycrystals is implemented based on an indium phosphide synthesis device with a phosphorus recovery device. The indium phosphide synthesis device is structurally divided into two parts: a phosphorus processing part and a polycrystal growth part.

[0031] See Figure 1 The phosphorus processing section includes a phosphorus heating device and a phosphorus recovery device. The phosphorus heating device is a quartz phosphorus container 3 arranged at the bottom, and a phosphorus heater 1 is arranged outside the quartz phosphorus container 3. The phosphorus recovery device includes a condenser 6 located at the top of the equipment, a liquid phosphorus channel arranged opposite to the condenser 6, and a liquid phosphorus delivery pipe 5 at the end of the liquid phosphorus channel. The liquid phosphorus delivery pipe 5 connects the space near the condenser 6 and the quartz phosphorus container 3. A plug 4 is provided at the bottom opening of the liquid phosphorus delivery pipe 5.

[0032] The liquid phosphorus channel is an inclined channel 13 , which gathers the liquid phosphorus to the upper opening of the liquid phosphorus delivery pipe 5 .

[0033] A liquid phosphorus heater 11 is provided on the periphery of the liquid phosphorus delivery pipe 5 .

[0034] The height of the liquid phosphorus delivery pipe 5 is greater than 4.2 times the height of the melt after the indium is melted.

[0035] See Figure 2 The polycrystalline growth part is a crucible 8, a heater 9 is arranged on the periphery of the crucible 8, and micron-sized holes 10 are arranged on the bottom of the crucible 8.

[0036] The phosphorus treatment part and the polycrystalline growth part are respectively provided with a sealing groove 14 and a sealing strip 15. The partition 16 is opened with a hole to match the size of the crucible 8. Figure 6 The small circle on the left side of the figure is an opening, and a sealing gasket is set at the opening to form a sealed space when the two parts are assembled together. Figure 3 .

[0037] A hole is provided on the partition plate 16 at a position corresponding to the bottom opening of the liquid phosphorus delivery pipe 5 .

[0038] Function description of each part:

[0039] Phosphorus heater 1 heats quartz phosphorus container 3, vaporizing the phosphorus therein. Heater 9 heats crucible 8, liquefying the indium therein to form a melt. When the pressure of the gaseous phosphorus in quartz phosphorus container 3 is high enough, the phosphorus gas enters the melt through micron-sized holes 10 at the bottom of crucible 8.

[0040] Due to the gravity of the sealing ball 4 - 3 in the sealing 4 , the sealing piece 4 - 1 seals the outlet of the liquid phosphorus delivery pipe 5 through the installation shaft 4 - 2 , and phosphorus gas will not escape from the liquid phosphorus delivery pipe 5 .

[0041] Phosphorus gas entering the melt reacts with indium to form indium phosphide. Some of the phosphorus gas escapes from the melt, rises to the top of the equipment, is cooled by condenser 6 into liquid phosphorus, and then falls into inclined channel 13. Under the action of gravity, the liquid phosphorus enters liquid phosphorus delivery pipe 5. At this point, the liquid phosphorus is white phosphorus.

[0042] To prevent heater 9 surrounding crucible 8 from heating liquid phosphorus delivery tube 5 and causing phosphorus vaporization, crucible 8 should be kept away from liquid phosphorus delivery tube 5. In this embodiment, the diameter of crucible 8 is approximately half the diameter of quartz phosphorus container 3, and crucible 8 and liquid phosphorus delivery tube 5 are respectively disposed on either side of quartz phosphorus container 3.

[0043] In order to further protect the liquid phosphorus delivery pipe 5 , a heat insulation layer may be provided on the outer periphery of the liquid phosphorus delivery pipe 5 .

[0044] In order to ensure that the phosphorus in the liquid phosphorus delivery pipe 5 remains in liquid state, in this embodiment, a liquid phosphorus heater 11 is provided on the periphery of the liquid phosphorus delivery pipe 5 .

[0045] Regardless of other factors inside the closed space (such as whether inert gas is filled), the pressure of phosphorus vapor must be greater than the pressure generated by the melt at the micron-sized pores 10 in order to pass through the micron-sized pores 10 and enter the melt.

[0046] The micron-sized holes 10 are located at the bottom of the crucible 8 and are at the same level as the partition 16 . The bottom opening of the liquid phosphorus delivery pipe 5 is also at the same level.

[0047] In order to ensure that all the escaped phosphorus gas enters the liquid phosphorus delivery pipe 5 after cooling and then enters the quartz phosphorus container 3, the sealing piece 4-1 must be opened before the liquid phosphorus delivery pipe 5 is filled with liquid phosphorus.

[0048] The pressure F1 of the liquid phosphorus entering the liquid phosphorus delivery pipe 5 at the bottom opening of the liquid phosphorus delivery pipe 5 must be greater than the pressure F2 exerted by the phosphorus vapor on the sealing piece 4-1 and the influence of the gravity of the sealing ball 4-3, so that the sealing piece 4-1 can be opened and some liquid phosphorus can flow into the quartz phosphorus container 3.

[0049] F2 is equal to the pressure F3 generated by the melt at the bottom of the crucible, F1>F2=F3.

[0050] F3 is related to the height and density of the melt, and F1 is related to the height and density of liquid phosphorus; the density of indium phosphide is 5.05g / cm 3 , the density of indium: 7.3g / cm 3 , density of liquid white phosphorus: 1.75g / cm 3 , considering that the melt is entirely indium, the pressure at the opening must reach F3, and the height of the liquid phosphorus in the liquid phosphorus delivery pipe 5 must reach 4.17 times the height of the melt.

[0051] Since the influence of gravity of the blocking balls 4 - 3 must be overcome, in this embodiment, the height of the liquid phosphorus delivery pipe 5 is greater than 4.2 times the height of the melt after indium is melted, ensuring that all the cooled liquid white phosphorus enters the liquid phosphorus delivery pipe 5 .

[0052] The present invention provides a method for synthesizing indium phosphide polycrystals, comprising the following steps:

[0053] 1.1. Loading Indium: Clean and dry the surface of indium 7 and load it into crucible 8;

[0054] 1.2. Phosphorus loading: Load red phosphorus 2 into the quartz phosphorus container 3;

[0055] 1.3. Assembly: Assemble the crucible 8 and the quartz phosphorus container 3 together; the assembled equipment is as follows Figure 3 As shown;

[0056] 1.4. Synthesis:

[0057] 1.4.1. Heating the indium 7 in the crucible 8 until the indium melts to form a melt;

[0058] 1.4.2. Open condenser 6 and introduce circulating coolant;

[0059] 1.4.3. The phosphorus 2 in the quartz phosphorus container 3 is heated and vaporized. The vaporized phosphorus vapor enters the melt in the crucible 8 through the micron-sized holes 10 at the bottom of the crucible 8 and reacts with indium to form indium phosphide.

[0060] 1.4.4. The phosphorus vapor overflowing from the melt exchanges heat with the condenser 6 and condenses into liquid droplets. The inclined channel 13 collects the liquid phosphorus to the upper opening of the liquid phosphorus delivery pipe 5 and flows into the liquid phosphorus delivery pipe 5. Figure 4 To prevent the liquid phosphorus from condensing into a solid, the liquid phosphorus heater 11 may be turned on to maintain the phosphorus above the liquefaction temperature;

[0061] 1.4.5. The liquid phosphorus level in the liquid phosphorus delivery pipe 5 gradually increases. When it reaches a certain height, the seal 4 is opened due to the pressure of the liquid phosphorus, and the liquid phosphorus flows into the quartz phosphorus container 3. Figure 5 As shown; the liquid phosphorus in the quartz phosphorus container 3 is heated and vaporized together with the red phosphorus, and enters the melt again to participate in the synthesis reaction;

[0062] 1.4.6. After the reaction is completed, stop the heater 9 and the phosphorus heater 1, cool to room temperature, disassemble the device, and take out the crucible 8.

[0063] In step 1.2, red phosphorus is placed into the quartz phosphorus container 3 under the protection of a nitrogen atmosphere.

[0064] During the above process, it is important to prevent the melt from dripping from the micron-sized holes 10 into the quartz phosphorus container 3 .

[0065] The molten metal is in a viscous state near its melting point and has a large surface tension. Therefore, in step 1.4.1, the heating temperature is maintained near the melting point of indium. In this embodiment, the heating temperature is 10-20°C higher than the melting point of indium, and the indium melt will not penetrate into small pores.

[0066] When the pressure of phosphorus vapor is large enough to overcome the pressure of the melt and enter the melt, the melt will not drip from the micron-sized holes 10 to the quartz phosphorus container 3. At this time, in step 1.4.3, the heating temperature is 10-20°C higher than the melting point of indium phosphide.

[0067] After the reaction is complete, heater 9 is first stopped, and the indium phosphide melt begins to solidify. Since phosphorus heater 1 is still operating, upward pressure is continuously generated at the location of micron-sized holes 10, preventing the indium phosphide melt from dripping. After the melt solidifies, phosphorus heater 1 is stopped. The pressure in quartz phosphorus container 3 decreases, seal 4 opens, and some liquid phosphorus in liquid phosphorus delivery pipe 5 flows into quartz phosphorus container 3. Liquid phosphorus heater 11 is stopped, and crucible 8 is removed.

[0068] At this time, there is still phosphorus in the quartz phosphorus container 3 and the liquid phosphorus delivery pipe 5, which will be used in the next synthesis.

Claims

1. A method for synthesizing indium phosphide polycrystals, which is implemented based on an indium phosphide synthesis device with a phosphorus recovery device, wherein the indium phosphide synthesis device comprises a quartz phosphorus container (3) arranged at the bottom, a phosphorus heater (1) arranged on the periphery of the quartz phosphorus container (3), a crucible (8) connected to the quartz phosphorus container (3), and a heater (9) arranged on the periphery of the crucible (8), characterized in that: a micron-sized hole (10) is provided at the bottom of the crucible (8); the indium phosphide synthesis device also comprises a phosphorus recovery device, comprising a condenser (6) located above the crucible (8), a liquid phosphorus channel arranged opposite to the condenser (6), and a liquid phosphorus delivery pipe (5) at the end of the liquid phosphorus channel, the liquid phosphorus delivery pipe (5) communicating with a space near the condenser (6) and the quartz phosphorus container (3), and a plug (4) is provided at the bottom opening of the liquid phosphorus delivery pipe (5); the liquid phosphorus channel is an inclined channel (13), and the inclined channel (13) gathers liquid phosphorus to the upper opening of the liquid phosphorus delivery pipe (5); and a liquid phosphorus heater (11) is provided on the periphery of the liquid phosphorus delivery pipe (5); The method comprises the following steps: 1.

1. Loading indium: Clean and dry the surface of indium and load it into the crucible (8); 1.

2. Phosphorus loading: Place red phosphorus into the quartz phosphorus container (3); 1.

3. Assembly: Assemble the crucible (8) and the quartz phosphorus container (3) together; 1.

4. Synthesis: 1.4.

1. Heating the indium in the crucible (8) until the indium melts to form a melt, wherein the heating temperature is 10-20° C. higher than the melting point of indium; 1.4.

2. Open the condenser (6) and introduce circulating coolant; 1.4.

3. The phosphorus in the quartz phosphorus container (3) is heated and vaporized, and the heating temperature is 10-20°C higher than the melting point of indium phosphide; the vaporized phosphorus vapor enters the melt in the crucible (8) through the micron-sized holes (10) at the bottom of the crucible (8), and reacts with indium to form indium phosphide; 1.4.

4. The phosphorus vapor overflowing from the melt exchanges heat with the condenser (6), condenses into liquid droplets, and flows into the liquid phosphorus delivery pipe (5); 1.4.

5. The liquid phosphorus level in the liquid phosphorus delivery pipe (5) gradually increases. When it reaches a certain height, the seal (4) opens due to the pressure of the liquid phosphorus, and the liquid phosphorus flows into the quartz phosphorus container (3); 1.4.

6. After the reaction is completed, stop the heater (9) and the phosphorus heater (1), cool to room temperature, disassemble the device, and remove the crucible (8).

2. The method according to claim 1, wherein: The height of the liquid phosphorus delivery pipe (5) is greater than 4.2 times the height of the melt after indium is melted.

3. The method according to claim 1, wherein: In step 1.2, red phosphorus is placed into a quartz phosphorus container (3) under the protection of a nitrogen atmosphere.

4. The method according to claim 1, wherein: In step 1.4.6, first stop the heater (9), and after the melt solidifies, stop the phosphorus heater (1).

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