WO2021098347A1 - System for preparing indium phosphide crystal from indium phosphorus mixture - Google Patents

Abstract

A system for preparing an indium phosphide crystal from an indium phosphorus mixture, relating to the technical field of semiconductors, and comprising a vacuum system, an inflation and deflation system, a temperature and pressure control system, an electric control system, a cooling circulation system, a weighing system, and a furnace body. The furnace body is provided with a crucible rod rotation lifting mechanism and a seed crystal rod lifting mechanism. The key is that: the furnace body is divided into a synthetic growth chamber (1), a feeding chamber (19), and a charging chamber (27). The charging chamber (27) and the feeding chamber (19) are separated by an insert plate (22). The charging chamber (27) is provided with an overturning feeder. The feeding chamber (19) is provided with a feeding pipe (18). One end of the feeding pipe (18) is fitted to the overturning feeder, and the other end extends into a crucible (10) in the synthetic growth chamber (1) to form a feeding structure of indium phosphorus mixed balls. The crucible (10) is positioned on a crucible rod (16). The seed crystal rod lifting mechanism is disposed on a top cover of the synthetic growth chamber (1). Indium phosphorus mixed balls (23) can be quickly put into the crucible (10) covered with liquid boron oxide, are synthesized, and are performed in-situ pulling to form an indium phosphide crystal, which makes the synthesis speed faster and facilitates industrial production.

Description

System for preparing indium phosphide crystal by using indium-phosphorus mixture Technical field

The invention belongs to the field of semiconductor technology, and relates to the preparation of indium phosphide, in particular to a method for synthesizing indium phosphide by using indium-phosphorus mixed balls.

Background technique

Indium phosphide (InP) is a group III-V compound semiconductor material formed by the combination of group III element indium (In) and group V element phosphorus (P). It has a very important strategic position in the field of semiconductor materials. An irreplaceable semiconductor material for devices and microelectronics. Compared with germanium and silicon materials, InP has many advantages: direct transition band structure, high electro-optical conversion efficiency; high electron mobility, easy to be made into semi-insulating materials, suitable for making high-frequency microwave devices and circuits; working temperature High; strong radiation resistance; high conversion efficiency as a solar cell material. Therefore, InP and other materials are widely used in high-tech fields such as solid-state lighting, microwave communications, optical fiber communications, microwaves, millimeter wave devices, and radiation-resistant solar cells. With the development of energy band engineering theory, ultra-thin material process technology and deep sub-micron manufacturing technology, InP has increasingly shown its advantages in high-end microwave, millimeter wave electronic devices and optoelectronic devices, and has become a high-end millimeter wave device. The material of choice is widely valued, and its development and application prospects are very broad. The realization of high-end InP-based microelectronics and optoelectronic devices depends on the preparation of high-quality InP single crystals with good integrity, uniformity and thermal stability. InP polycrystalline materials with high purity, different melt ratios and no inclusions are the prerequisites for the production of high-quality InP single crystals and the research on InP-related characteristics. Many characteristics of InP single crystal are related to the characteristics of the starting material, that is, the polycrystalline material, such as the proportion of the polycrystalline material and the purity of the material. The characteristics of polycrystalline materials have a great influence on crystal growth, crystal electrical performance, crystal integrity and uniformity.

At present, several commonly used methods for synthesizing InP polycrystalline materials and their existing problems are as follows:

(1) Horizontal Bridgman method (HB) and horizontal gradient solidification method (HGF): The horizontal Bridgman method (HB) and horizontal gradient solidification method (HGF) are used to synthesize InP materials. In terms of technology, the larger the synthesis amount, the longer the synthesis time. Generally, it takes about 24 hours to synthesize 1.5KgInP polycrystalline with HB/HGF technology, so the contamination of Si is also more obvious (the source is the quartz tube wall).

(2) Phosphorus injection synthesis technology: Phosphorus injection synthesis technology is to inject vaporized phosphorus vapor into the indium melt, accelerate the contact area of the phosphorus gas and the indium melt, and increase the convection in the indium melt through the rotation of the crucible , To accelerate the diffusion of solute in the solute diffusion layer, thereby speeding up the synthesis process. Because this method relies on the pressure difference between the inside and outside of the quartz phosphorus container to inject phosphorus vapor, once the pressure difference is not properly controlled, it is easy to explode. On the other hand, part of the phosphorus vapor is not absorbed by the indium melt, which affects the synthesis effect on the one hand, and on the other On the one hand, the lost phosphorus vapor volatilizes into the furnace body, which brings great trouble to the furnace body cleaning. And it has very high requirements for the thermal field control in the synthesis system.

The above-mentioned synthesis methods such as horizontal Bridgman method (HB), horizontal gradient solidification method (HGF) and ultra-high pressure direct synthesis technology are all InP synthesis in the synthesis furnace, and then the synthesized InP polycrystalline material is taken out of the synthesis furnace , The polycrystalline material is cleaned and corroded, and then loaded into the high-pressure single crystal furnace for InP single crystal growth. Synthesis and crystal growth are carried out using a "two-step" method, which greatly increases the possibility of material contamination and increases the cost of material preparation.

Summary of the invention

The invention provides a system for preparing indium phosphide using indium-phosphorus mixture, which can quickly put indium-phosphorus mixed balls into a crucible covered with liquid boron oxide. After the required synthesis amount is reached, the indium-phosphorus melt Pulling to form indium phosphide crystals can make the synthesis faster, reduce control requirements, and facilitate industrial production.

The technical scheme of the present invention is: a system for preparing indium phosphide crystals using indium-phosphorus mixtures, including a vacuum system, a charging and discharging system, a temperature and pressure control system, an electrical control system, a cooling cycle system, a weighing system and a furnace body The furnace body is provided with a crucible rod rotation lifting mechanism and a seed crystal rod lifting mechanism. The key is that the furnace body is divided into a synthesis growth chamber, a feeding chamber, and a charging chamber. The charging chamber and the feeding chamber are separated by a plug-in plate. An inverting feeder is set in the material chamber, and a feeding tube is set in the feeding chamber. One end of the feeding tube is upwardly connected to the inverting feeder, and one end extends downward into the crucible in the synthetic growth chamber to form an indium-phosphorus mixed ball feeding structure; the crucible is positioned on the crucible rod, and the seed The crystal rod lifting mechanism is arranged on the top cover of the synthetic growth chamber.

In this system, by dividing the furnace body into a synthetic growth chamber, a feeding chamber, and a charging chamber, the indium-phosphorus mixed ball can be loaded into the flip feeder of the charging chamber, and then through the feeding chamber and the feeding tube of the synthetic growth chamber, The indium-phosphorus mixed ball is put into the crucible for melting and synthesis, and the crystal growth can be carried out in situ after synthesis. The feeding chamber and the charging chamber are separated by a plug-in plate, can communicate during feeding, and can be isolated when charging the carrier, so as to realize the synthesis or crystal growth in the synthesis growth chamber while loading and replenishing.

Further, the overturning feeder includes a mechanical arm, a material carrier and a material carrier overturning drive device. The upper end of the mechanical arm is positioned at the top of the loading chamber, the lower end is connected to the overturning drive device, and the overturning drive device is connected to the material carrier. The mechanical arm plays the role of installation and positioning, and is used to suspend the carrier in the loading chamber to facilitate airtight and low-temperature feeding. The turning drive device is used to drive the feeder to turn and feed the material.

Further, in order to simplify the structure and facilitate control, the material carrier turning drive device adopts a motor positioned at the bottom end of the mechanical arm, and the motor shaft is connected to the material carrier.

Further, in order to prevent the environment in the furnace from affecting the performance of the motor, the exterior of the motor is covered with a heat insulation layer and a protective cover.

Further, the gas charging and discharging system includes a low-temperature inert gas storage tank, an air inlet and an air outlet separately arranged at the top of the loading chamber and the bottom of the synthetic growth chamber, and the air inlet is higher than the inlet of the feeding pipe; The charging chamber enters the feeding chamber, enters the synthetic growth chamber through the feeding pipe, and is sent to the top of the crucible and discharged from the exhaust port. The system needs to control the temperature of the inert gas to be lower than the melting point of indium, that is, the temperature is lower than 156°C. The flow of low-temperature inert gas can keep the indium-phosphorus mixed ball from the carrier to the crucible at a low temperature. Indium or phosphorus does not melt or vaporize, so as to prevent indium from melting and sticking to the wall and preventing phosphorus from volatilizing during the delivery process. , To avoid affecting the synthesis ratio.

Further, the pressure value in the furnace body is 3.5-5.0 MPa. The pressure is higher than the dissociation pressure of the indium phosphide melt, which can prevent the dissociation of indium phosphide to ensure the progress of synthesis and growth. At the same time, because the pressure of the feeding chamber is higher than the synthesis growth chamber by 0.05-0.1Mpa, and the low-temperature gas will enter from above, it can ensure that the indium-phosphorus mixed ball and the low-temperature gas enter the crucible above the synthesis growth space together to prevent the indium-phosphorus mixed ball from being "Indium or phosphorus melts and vaporizes" before entering the melt.

Further, in order to facilitate observation of the synthesis and crystal growth, a first observation window is provided on the furnace wall of the synthesis growth chamber. In order to facilitate the observation of the charging and feeding conditions of the flip feeder, a second observation window is provided on the furnace wall of the charging chamber.

Further, in order to facilitate charging, a charging door is provided on the top of the charging chamber.

Further, in order to isolate and seal the charging chamber and the charging chamber, a sealing ring I is arranged between the insert plate and the furnace wall. In order to facilitate material receiving and feeding, the feeding pipe includes a funnel section at the top and a vertical pipe section or an inclined pipe section leading from the feeding chamber into the synthetic growth chamber.

Further, in order to assist in maintaining a low temperature environment, the interposer has an interlayer, and cooling water is passed through the interlayer. In order to cool the indium-phosphorus mixed ball and prevent the feed pipe from being damaged by overheating, cooling water is passed through the pipe wall of the vertical pipe section or the inclined pipe section.

The beneficial effects of the present invention are as follows: 1. With the system, the indium-phosphorus mixed ball with a good proportion can be directly put into the crucible for melting and synthesis, and the crystal growth can be carried out in situ after synthesis; the operation process is simplified, and the operation process is reduced. Control requirements, faster synthesis speed and higher crystal preparation efficiency, which is conducive to industrial production. 2. Using this system to prepare indium phosphide crystals can reduce the volatilization of phosphorus, reduce material pollution, improve crystal purity, reduce material costs, and facilitate the synthesis and growth of high-quality indium phosphide crystals.

Description of the drawings

1 is a schematic diagram of the structure of the indium phosphide crystal system prepared by the indium-phosphorus mixture in the first embodiment;

Figure 2 Mechanism diagram of the reaction process when the indium-phosphorus mixture is put into the In-P melt;

Figure 3 is a schematic diagram of the structure of the charging chamber in the first embodiment when replenishing;

Figure 4 is a schematic diagram of the structure of the vertical feeding pipe in the second embodiment;

Figure 5 is a schematic diagram of the structure of the flip feeder in the embodiment;

6 is a schematic diagram of the connection structure of the motor and the material carrier in the embodiment;

In the figure, 1 represents the synthetic growth chamber, 2 represents the seed crystal rod, 3 represents the seed crystal, 4 represents the melt thermocouple, 5 represents the crystal, 6 represents the pressure gauge I, 7 represents the vacuum gauge I, and 8 represents the insulation jacket , 9 stands for main heater, 10 stands for crucible, 11 stands for boron oxide covering agent, 12 stands for indium-phosphorus melt, 13 stands for crucible support, 14 stands for lower heater, 15 stands for exhaust port, 16 stands for crucible rod, 17 stands for The first observation window, 18 represents the feeding tube, 19 represents the feeding chamber, 20 represents the vacuum gauge II, 21 represents the pressure gauge II, 22 represents the insert plate, 22-1 represents the sealing ring I, 23 represents the indium-phosphorus mixed ball, and 24 represents the carrier For the hopper, 25 is the vacuum gauge III, 26 is the pressure gauge III, 27 is the charging chamber, 28 is the robotic arm, 29 is the charging door, 30 is the second observation window, and 31 is the air inlet. 32 represents the turning drive device, 32-1 represents the protective cover, 32-2 represents the heat insulation layer, 32-3 represents the motor, 32-4 represents the sealing ring II, 32-5 represents the pin, 33 represents the wire, and 34 represents the flange.

Detailed ways

The present invention will be described in detail below with reference to the drawings and embodiments.

The first embodiment is a system for preparing indium phosphide crystals using an indium-phosphorus mixture, including a vacuum system, a gas charging and discharging system, a temperature and pressure control system, an electrical control system, a cooling cycle system, and a weighing system. These systems are commonly used basic systems in the field, especially single crystal furnaces based on in-situ synthesis to prepare indium phosphide crystals. These systems are basic configurations and will not be repeated here. In order to realize the preparation of indium phosphide crystals by using indium-phosphorus mixed balls, the present invention improves the furnace body.

Referring to Figure 1, the furnace body is divided into a synthetic growth chamber 1, a feeding chamber 19 and a charging chamber 27. The charging chamber 27 and the charging chamber 19 are separated up and down by means of an insert plate 22, and a sealing ring is arranged between the insert plate 22 and the furnace wall Ⅰ22-1, when the plug-in board is inserted, the charging chamber 27 and the feeding chamber 19 can be isolated and sealed. An inverting feeder is arranged in the charging chamber 27, and a feeding tube 18 is arranged in the feeding chamber 19, one end of the feeding tube 18 is connected to the inverting feeder upward, and one end extends downward into the synthetic growth chamber 1.

The synthetic growth chamber 1 is provided with a lower heater 14, a main heater 9, an insulation jacket 8, a crucible 10, a supporting crucible support 13 and a crucible rod 16. The crucible 10 is located on the graphite crucible support 13, and the crucible support 13 is fixedly connected to the crucible rod 16. The lower heater 14 and the main heater 9 are arranged on the periphery of the crucible 10 and the crucible support 13, and an insulation jacket 8 is provided between the main heater 9 and the inner wall of the synthetic growth chamber 1. The other end of the crucible rod 16 extends beyond the furnace bottom of the synthesis growth chamber 1 and is connected to the crucible rod rotating and lifting mechanism. The crucible rod rotation lifting mechanism is a common basic mechanism for single crystal furnaces and synthesis furnaces in the field, and is used to drive the crucible to rise and fall and rotate, so that the indium and phosphorus are mixed uniformly and the reaction is sufficient, which will not be repeated here. A seed crystal rod 2 is arranged above the crucible 10, a seed crystal 3 and a load cell are fixed on the seed crystal rod 2, and the seed crystal rod 2 penetrates the top cover of the synthetic growth chamber 1 to connect to the seed crystal rod lifting mechanism. The seed crystal rod lifting mechanism can drive the seed crystal 3 up and down to lift and grow the crystal. The load cell and weighing system can calculate the growth weight of the crystal. The seed crystal rod 2, the weighing sensor and the weighing system, and the seed crystal rod lifting mechanism are common basic mechanisms of the single crystal furnace for pulling and growing crystals, and will not be repeated here. The synthetic growth chamber 1 is also provided with a melt temperature measuring thermocouple 4, a pressure gauge I 6, and a vacuum gauge I 7, with an exhaust port 15 at the bottom and a first observation window 17 at the top. A vacuum gauge II 20 and a pressure gauge II 21 are installed on the furnace wall of the feeding chamber 19. The feeding pipe 18 includes a funnel section at the top and an oblique pipe section leading into the synthesis growth chamber 1 from the feeding chamber 19, and the oblique pipe section extends above the crucible 10.

A charging door 29 is provided on the top of the charging chamber, an air inlet 31 is provided on the furnace wall, a vacuum gauge III 25 and a pressure gauge III 26 are installed, and a second observation window 30 is provided on the charging door 29. The overturning feeder in the loading chamber 27 includes a mechanical arm 28, a carrier 24, and a carrier overturning drive device 32. See Figures 5 and 6, the upper end of the mechanical arm 28 is positioned on the top of the loading chamber 27, and the lower end is connected to the overturning drive. The device 32 and the turning drive device 32 are connected to the carrier 24. The feeder turning drive device 32 uses a motor 32-3 positioned at the bottom end of the mechanical arm 28, and the motor 32-3 shaft is connected to the feeder 24 by a pin 32-5. The outside of the motor 32-3 is covered with a heat insulation layer 32-2 and a protective cover 32-1, the motor shaft is covered with a flange 34, and a sealing ring II 32-4 is provided. The wire 33 passes through the robot arm 28 to connect to the electrical control system.

The charging and discharging system includes a low-temperature inert gas storage tank, an air inlet 31 and an air outlet 15. The inert gas below 156° C. enters the feeding chamber 19 from the charging chamber 27, enters the synthetic growth chamber 1 through the feeding pipe 18, and is discharged from the exhaust port 15. The pressure in the furnace body is 3.5-5.0MPa.

The second embodiment, referring to FIG. 4, the difference between this embodiment and the first embodiment is: in this embodiment, the feeding tube 18 is a straight tube, and the synthesis growth chamber 1 and the feeding chamber 19 are stacked in a staggered manner so that the feeding tube 18 can pass into the crucible. In 10, the first observation window 17 is located on the side wall of the synthetic growth chamber 1.

The steps of applying this system to prepare indium phosphide crystals are:

1) High-purity indium powder and high-purity phosphorous powder are mixed uniformly according to a mass ratio of 3.7:1.0-1.5, and pressed into spherical indium-phosphorus mixed balls 23.

2) Put the indium phosphorus mixed ball 23 mixed with boron oxide powder into the carrier 24 in the charging chamber 27, and put the massive boron oxide into the crucible 10.

3) Vacuum the entire system to 10-10 ^-5 Pa through the air inlet 31, and then charge the inert gas below 156°C into the feeding chamber 19 and the feeding chamber 27 through the air inlet 31, and the low-temperature inert gas passes through The feeding pipe 18 enters the synthesis and growth chamber 1, so that the indium-phosphorus mixed ball 23 is always kept at a low temperature. Throughout the synthesis process, the gas flow between the air inlet 31 and the air outlet 15 is maintained and the pressure is stable, and the pressure value is between 3.5-5.0 MPa, and the pressure of the feeding chamber 19 is higher than the pressure of the synthesis growth chamber 1 by 0.05-0.1 MPa.

4) The crucible 10 is heated by the main heater 9 and the lower heater 14, and the crucible 10 is rotated to 5-35 revolutions per minute. After the massive boron oxide is melted, the whole crucible 10 is spread to form the boron oxide covering agent 11, and the melt The thermocouple 4 is inserted into the interface between the boron oxide covering agent 11 and the bottom of the crucible 10.

5) The indium-phosphorus mixed ball 23 in the carrier 24 is sent to the feed pipe 18 through the mechanical arm 28, the indium-phosphorus mixed ball 23 falls into the crucible 10, and the indium phosphorus at the mouth of the feed pipe 18 is observed through the first observation window 17. The drop of the mixing ball 23. Referring to Fig. 2, for the first or consecutive previous several indium-phosphorus mixed balls 23, the indium in the indium-phosphorus mixed balls 23 melts, and the phosphorus is heated to sublimate into phosphorus gas, and the phosphorus gas reacts with the indium melt and is absorbed by it to form Indium-phosphorus melt 12. The indium in the subsequent indium-phosphorus mixed ball 23 melts and reacts with the indium-phosphorus melt 12 to form a new composition of indium-phosphorus melt 12. The phosphorus of the indium-phosphorus mixed ball 23 is sublimated into phosphorus gas by heating, and the phosphorus gas and indium- The phosphorus melt 12 reacts and is absorbed by it. After the amount of indium-phosphorus melt 12 is synthesized to cover the bottom of the crucible, the seed crystal 3 is lowered and the boron oxide covering agent 11 is pulled out.

6) Observe the number of indium-phosphorus mixed balls 23 in the carrier 24 through the second observation window 30. After the indium-phosphorus mixed ball 23 in the carrier 24 has been thrown, referring to FIG. 3, insert the insert plate 22 to separate the feeding chamber 19 from the charging chamber 27, and the synthesis and growth chamber 1 will continue the pulling growth. At the same time, release the high-pressure gas in the charging chamber 27 from the air inlet 31 to atmospheric pressure, then open the charging door 29, put the indium-phosphorus mixed ball 23 into the carrier 24, close the charging door 29, from the inlet The port 31 is evacuated and filled with an inert gas below 156°C until the pressure in the charging chamber 27 is the same as the synthesis and growth chamber 1 and the feeding chamber 19, the plug 22 is opened, and the indium phosphorus in the carrier 24 is removed by the mechanical arm 28. The mixing ball 23 is sent to the crucible 10 through the feed pipe 18 to continue the synthesis, and continues to be pulled to form the crystal 5.

Claims (10)

A system for preparing indium phosphide crystals using indium-phosphorus mixtures, including a vacuum system, a gas charging and discharging system, a temperature and pressure control system, an electrical control system, a cooling cycle system, a weighing system, and a furnace body. The furnace body is provided with a crucible The rod rotation lifting mechanism and the seed crystal rod lifting mechanism are characterized in that the furnace body is divided into a synthetic growth chamber (1), a feeding chamber (19) and a charging chamber (27), a charging chamber (27) and a feeding chamber (19) With the help of a plug-in plate (22), a flip feeder is installed in the charging chamber (27), and a feeding tube (18) is set in the feeding chamber (19). One end of the feeding tube (18) is connected to the flip feeder upwards, and one end faces upwards. The crucible (10) extending downward into the synthetic growth chamber (1) forms an indium-phosphorus mixed ball delivery structure; the crucible (10) is positioned on the crucible rod (16), and the seed crystal rod lifting mechanism is arranged in the synthetic growth chamber (1) ) On the top cover. The system for preparing indium phosphide crystals using an indium-phosphorus mixture according to claim 1, characterized in that: the turnover feeder comprises a mechanical arm (28), a feeder (24) and a feeder turnover driving device (32) ), the upper end of the mechanical arm (28) is positioned at the top of the loading chamber (27), the lower end is connected with a turning drive device (32), and the turning drive device (32) is connected with the material carrier (24). The system for preparing indium phosphide crystals using an indium-phosphorus mixture according to claim 2, characterized in that: the carrier turnover driving device (32) is a motor (32-3) positioned at the bottom end of the robotic arm (28) , The shaft of the motor (32-3) is connected with the material carrier (24). The system for preparing indium phosphide crystals by using indium-phosphorus mixture according to claim 3, characterized in that: the exterior of the motor (32-3) is covered with a heat insulation layer (32-2) and a protective cover (32- 1). The system for preparing indium phosphide crystals using an indium-phosphorus mixture according to claim 1, characterized in that: the charging and discharging system comprises a low-temperature inert gas storage tank, which is separately arranged on the top of the charging chamber (27) and the synthetic growth chamber ( 1) The air inlet (31) and exhaust port (15) at the bottom, the air inlet (31) is higher than the inlet of the feeding pipe (18); the inert gas below 156°C enters the feeding chamber (27) The chamber (19) enters the synthesis growth chamber (1) through the feed pipe (18), is sent to the top of the crucible (10), and is discharged from the exhaust port (15). The system for preparing indium phosphide crystals using an indium-phosphorus mixture according to claim 5, characterized in that the pressure in the furnace body is 3.5-5.0Mpa, and the pressure of the feeding chamber (19) is higher than that of the synthetic growth chamber (1). )0.05-0.1MPa. The system for preparing indium phosphide crystals using an indium-phosphorus mixture according to claim 1, wherein a first observation window (17) is provided on the furnace wall of the synthetic growth chamber (1), and the charging chamber A second observation window (30) is provided on the furnace wall of (27). The system for preparing indium phosphide crystals using an indium-phosphorus mixture according to claim 1, characterized in that: a charging door (29) is provided on the top of the charging chamber. The system for preparing indium phosphide crystals using indium-phosphorus mixture according to claim 1, characterized in that: a sealing ring I (22-1) is arranged between the insert plate (22) and the furnace wall, and the feeding tube (18) It includes a funnel section at the top and a vertical pipe section or an inclined pipe section leading into the synthetic growth chamber (1) from the feeding chamber (19). The system for preparing indium phosphide crystals using an indium-phosphorus mixture according to claim 1, characterized in that cooling water is passed through the wall of the vertical pipe section or the inclined pipe section, and the insert plate (22) has a partition, and the inside of the partition Cooling water is provided.

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