CN110904510A

CN110904510A - Single crystal furnace for InSb crystal growth

Info

Publication number: CN110904510A
Application number: CN201911058138.6A
Authority: CN
Inventors: 柏伟; 刘江高; 徐强强; 刘铭
Original assignee: CETC 11 Research Institute
Current assignee: CETC 11 Research Institute
Priority date: 2019-11-01
Filing date: 2019-11-01
Publication date: 2020-03-24

Abstract

The invention discloses a single crystal furnace for InSb crystal growth. The single crystal furnace comprises: a reverse flow heat insulation layer arranged above a quartz crucible, the reverse flow heat insulation layer is connected to a pulling device through a fixed rod frame, so The bottom end of the backflow heat insulating layer is inclined to the InSb crystal direction in the middle of the quartz crucible with a certain taper angle inclination, which is used to make corresponding adjustments according to the actual growth interface shape in different stages of the InSb crystal growth under the driving of the pulling device. In the process of InSb crystal growth, the grown crystal is partially shielded or reflected a certain amount of radiant heat, and the thermal field structure of the single crystal furnace is changed; one end of the fixed rod frame is connected with the reverse flow heat insulation layer, and Passing through the furnace wall of the single crystal furnace, the other end is connected to the pulling device, which is used to drive the reverse flow insulation layer to move up and down under the driving of the pulling device; the pulling device is connected to the reverse flow insulation layer through a fixed rod frame, It is used to drive the backflow heat insulation layer to move up and down through the fixed rod frame.

Description

Single crystal furnace for InSb crystal growth

Technical Field

The invention relates to the field of single crystal furnaces, in particular to a single crystal furnace for InSb crystal growth.

Background

InSb is used as a III-V group compound semiconductor material and has the characteristics of narrow forbidden band width, small electron effective mass and high electron mobility, and the physical and chemical properties are stable. As the infrared detector belongs to intrinsic absorption in a medium wave band of 3-5 mu m, the infrared detector based on InSb has extremely high quantum efficiency and response rate, and therefore InSb becomes a preferred material for the medium wave infrared detector. The InSb infrared detector is subjected to rapid development of units, multiple elements, one-dimensional linear arrays and two-dimensional area arrays, so that the performance of an infrared system is greatly improved, and the application of the infrared technology in the fields of astronomical observation, reconnaissance and monitoring, search and tracking, driving assistance, fire fighting, safety production and the like is facilitated. In order to meet the development of a new generation of ultra-large array infrared focal plane detector with mega pixels, high integration degree and the like, and simultaneously reduce the manufacturing cost of the detector and the like, the development requirement of large-size and high-quality InSb crystals is higher and higher. The large-size InSb crystal with low defect density and high electrical uniformity is a key basis for preparing a high-performance large-size infrared focal plane detector. The mainstream preparation method of the InSb crystal is to grow the InSb crystal by the czochralski method, and then prepare various types of wafers through processes of cutting, chamfering, grinding, polishing and the like. In the process of growing InSb crystals by the Czochralski method, firstly, polycrystalline raw materials are placed in a quartz crucible to be heated and melted, the temperature field in a furnace is adjusted, then, seed crystals fixed on seed crystal rods are immersed into a melt from the surface of the melt, and after partial melting, the seed crystal rods are slowly pulled upwards and rotated. Through the heat dissipation of the seed crystal rod and the shoulder part at the initial stage of crystal growth, the melt in contact with the seed crystal firstly obtains a certain supercooling degree, and then crystallization occurs; with the continuous pulling and rotation of the seed rod, the crystallization process is continuously carried out, thereby realizing the continuous growth of the crystal. For the growth of large-size and high-quality InSb crystals by the Czochralski method, the thermal stress corresponding to a relatively flat or slightly convex growth interface in the crystal growth process is low, which is an important condition for preparing the large-size and high-quality InSb crystals with low defect density and uniform electrical parameters. The shape of the growth interface is mainly dependent on the heat flow conditions near the growth interface. In the czochralski method InSb crystal growth furnace, the heat flow near the growth interface mainly comprises: radiant heat of the crucible wall to the melt and the crystal, convective heat transfer of the melt, radiant heat dissipation of the melt surface and the crystal surface to the environment, conductive heat dissipation of the crystal from the seed rod, and the like.

At present, the research on growth interface control in the InSb crystal growth process is rarely reported at home and abroad, the convection heat transfer of a melt is generally changed by changing the crucible rotation speed or the crystal rotation speed in a matching way in the conventional growth interface control at present, and the shape of a growth interface is further changed to a certain extent, but the convection phenomenon is the overall expression of coupling of the melt, the crystal and a temperature field, the convection condition can be influenced by any tiny temperature, liquid level and heat preservation system change in the InSb crystal growth process, the conventional regulation and control method can generate results which are difficult to predict, effective matching parameters are difficult to find, a large number of tests are required to be carried out and relevant rules are summarized, the whole period is long, the cost is extremely high, and the effect is not obvious. In addition, the external environment and condition influence in the crystal growth process is huge, the variables are numerous, the traditional regulation and control method is difficult to realize accurate, efficient and flexible regulation and control, convection cannot be effectively and controllably regulated, the change that the convection state is difficult to predict is easily caused, not only the convection cannot be inhibited, but also the convection fluctuation can be enhanced, the crystal structure is seriously damaged, and therefore additional adverse influence is generated on the uniformity of crystal defects and element doping. Therefore, it is the key to solve the above problems that the flexible control and adjustment of the thermal field is fundamentally performed to realize the effective control of the growth interface of the InSb crystal.

The relatively flat or slightly convex growth interface is an effective way for preparing large-size and high-quality InSb crystals with low defect density and high electrical uniformity, the shape of the growth interface can be improved to a certain extent by changing the convection heat transfer of a melt by using a traditional method through changing the crucible rotating speed or the crystal rotating speed, but the change of a convection state which is difficult to predict is more easily caused, so that the additional adverse effect is generated on the uniformity of crystal defects and element doping.

Disclosure of Invention

The embodiment of the invention provides a single crystal furnace for InSb crystal growth, which is used for solving the problems in the prior art.

The embodiment of the invention provides a single crystal furnace for InSb crystal growth, which comprises:

the device comprises a backflow heat insulation layer arranged above a quartz crucible, wherein the backflow heat insulation layer is connected to a pulling device through a fixing rod frame, the bottom end of the backflow heat insulation layer inclines towards the InSb crystal in the middle of the quartz crucible with a certain taper angle, the backflow heat insulation layer is used for carrying out corresponding position adjustment according to the actual growth interface shape at different stages of InSb crystal growth under the driving of the pulling device, and in the InSb crystal growth process, a grown crystal part is directionally shielded or reflects certain radiant heat to change the thermal field structure of a single crystal furnace;

one end of the fixed rod frame is connected with the backflow heat insulation layer and penetrates through the furnace wall of the single crystal furnace, and the other end of the fixed rod frame is connected with the lifting device and is used for driving the backflow heat insulation layer to move up and down under the driving of the lifting device;

the lifting device is connected with the backflow heat insulation layer through the fixing rod frame and used for driving the backflow heat insulation layer to move up and down through the fixing rod frame.

By adopting the embodiment of the invention, the problem that the change of the crucible rotating speed or the crystal rotating speed in the traditional method easily causes violent and uncontrollable change of the convection state, thereby causing additional adverse effects on the crystal defects and the uniformity of element doping is solved, the thermal field can be fundamentally and flexibly controlled and adjusted, so that the effective control on the growth interface of the InSb crystal is realized, the relatively flat or slightly convex growth interface shape is obtained, and the large-size and high-quality InSb crystal with low defect density and uniform electrical parameters is prepared.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a schematic view of a single crystal furnace for InSb crystal growth according to an embodiment of the present invention;

FIG. 2 is a schematic view of a lifting device for a reverse flow insulation layer according to an embodiment of the present invention;

fig. 3 is a diagram showing the results of the InSb crystal growth interface in the example of the present invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The embodiment of the invention relates to a single crystal furnace for InSb crystal growth, which is used for controlling an InSb crystal growth interface. A specially designed thermal field structure is provided and matched with corresponding movement, and the two are combined to form a complete technical scheme. The method is different from the traditional method that the convection heat transfer of the melt is changed by changing the crucible rotating speed or the crystal rotating speed so as to change the shape of the growth interface to a certain extent.

According to an embodiment of the invention, a single crystal furnace for InSb crystal growth is provided, and fig. 1 is a schematic view of the single crystal furnace for InSb crystal growth according to the embodiment of the invention, as shown in fig. 1, wherein 1 is an InSb seed crystal, 2 is an InSb crystal, 3 is an induction heating coil, 4 is a graphite induction heating body, 5 is a quartz crucible, 6 is a graphite collet, 7 is a corundum support rod, 8 is an InSb melt, 9 is a backflow heat-insulating layer, and 10 is a backflow heat-insulating layer fixing rod frame. FIG. 2 is a schematic view of a pulling apparatus for a reverse flow heat insulating layer according to an embodiment of the present invention, as shown in FIG. 2, 11 is a furnace wall of a single crystal furnace, 12 is a connecting bellows, 13 is an airtight outer cover, and 14 is a lifting driving motor. The single crystal furnace for InSb crystal growth according to the embodiment of the invention specifically comprises:

the backflow heat-insulating layer 9 is arranged above the quartz crucible 5, the backflow heat-insulating layer 9 is connected to the pulling device through a fixing rod frame 10, the bottom end of the backflow heat-insulating layer inclines towards the InSb crystal in the middle of the quartz crucible with a certain taper angle, and the backflow heat-insulating layer is used for carrying out corresponding position adjustment according to the actual growth interface shape at different stages of InSb crystal growth under the driving of the pulling device; the backflow heat insulation layer 9 is made of high-purity quartz. The cone angle inclination is adjusted correspondingly according to the growing crystals with different sizes.

One end of the fixed rod frame 10 is connected with the backflow heat-insulating layer 9 and penetrates through the furnace wall of the single crystal furnace, and the other end of the fixed rod frame is connected with the lifting device and is used for driving the backflow heat-insulating layer to move up and down under the driving of the lifting device;

the lifting device is connected with the backflow heat-insulating layer 9 through the fixing rod frame 10 and is used for driving the backflow heat-insulating layer 9 to move up and down through the fixing rod frame 10.

The lifting device specifically comprises:

one end of the connecting corrugated pipe 12 is connected with the outer side of the furnace wall 11 where the fixed rod frame penetrates, and the other end of the connecting corrugated pipe is connected with the air-tight outer cover, is sleeved on the outer side of the fixed rod frame and is used for telescopic motion under the driving of the lifting driving mechanism;

an airtight housing 13 connected to the connection bellows 12 for ensuring a vacuum state inside the single crystal furnace;

and the lifting driving mechanism 14 is arranged in the airtight outer cover 13, is connected with the fixed rod frame 10 and is used for driving the fixed rod frame 10 to move up and down. The pulling device is similar to a seed rod that can move up and down.

In the embodiment of the invention, the temperature of the crystallization area is automatically regulated and controlled by a single crystal furnace temperature feedback system to realize the regulation of the relative balance position of the backflow heat-insulating layer and the InSb crystal growth interface.

The above-described technical means will be described in detail below.

The embodiment of the invention adopts a specially designed thermal field structure combined with corresponding motion coordination to flexibly and effectively control the growth interface in the growth process of the InSb crystal. A backflow heat insulation layer which is obliquely arranged downwards is designed in a thermal field structure of the single crystal furnace and is made of high-purity quartz. The cone angle gradient of the backflow heat-insulating layer can be correspondingly adjusted according to the growing crystals with different sizes. The reflux heat insulation layer is positioned above the quartz crucible, one side of the reflux heat insulation layer is connected with a lifting device through a quartz fixing rod frame, the lifting device is similar to a seed rod which can move up and down, and the reflux heat insulation layer penetrates through a furnace wall and is connected with a lifting driving mechanism. The corresponding position adjustment can be carried out on the backflow heat-insulating layer according to the actual growth interface shape at different stages of the InSb crystal growth, the problems of flexibility and effective control of the growth interface in the crystal growth process are solved, and the relatively flat or slightly convex growth interface shape is obtained. The thermal field structure with special design is combined with a corresponding backflow heat-insulating layer movement matching method, namely, the relative position of the thermal field components around the backflow heat-insulating layer is changed by lifting the backflow heat-insulating layer, so that good temperature gradient and ideal temperature distribution can be obtained, the growth interface shape of the crystal can be corrected, and the growth interface in the crystal growth process can be placed in a completely controllable state.

In the InSb crystal growth process, the backflow heat insulation layer can shield or reflect certain radiant heat in a directional mode. The annular induction heating coil heats the melt, so that the melt flows upwards along the edge of the crucible and descends in the middle of the quartz crucible or below the crystal to form a circulating flow return field. The radial temperature profile at the crystal growth interface is a key factor affecting the generation of various defects and the distribution of doping elements in the crystal. A backflow heat insulation layer is additionally arranged above the quartz crucible, so that excessive radiant heat can be directionally shielded for a grown crystal part, meanwhile, the radiant heat can be reflected to a corresponding melt, a reverse convection flow field which flows around from the center to the edge is generated at a crystal growth interface, the convection flow field and a natural convection flow field are converged between the outer side of the crystal and the crucible wall, the convection flow field and the natural convection flow field are partially offset, the integral convection effect is reduced, the radial temperature gradient of the crystal is reduced, the defect density in the crystal is reduced, and the uniformity of element doping is improved. In addition, in different crystal growth stages, the backflow heat-insulating layer can be correspondingly and accurately adjusted according to the actual growth interface shape, the shielding or reflected radiant heat around the backflow heat-insulating layer can be flexibly and effectively adjusted, so that the backflow heat-insulating layer and the growth interface are in relative balance positions, the flatness of the growth interface is ensured, and the large-size and high-quality InSb crystal is obtained. The adjustment of the relative balance position of the backflow heat-insulating layer and the growth interface can be realized by automatically regulating and controlling the temperature of the crystallization area through a single crystal furnace temperature feedback system. The temperature fluctuation of the outer wall of the quartz crucible at the fixed distance of the crystal growth interface is less than +/-0.1 ℃ and the environmental temperature fluctuation of the crystal low-temperature area at the fixed distance of the crystal growth interface is less than +/-0.1 ℃ by accurately regulating and controlling the position of the backflow heat-insulating layer and then matching with the crystal growth process parameters, so that the difficult problem of flexibly and effectively controlling the crystal growth interface is fundamentally solved.

As described above, the embodiments of the present invention solve the problem of flexible and effective control of the growth interface during the InSb crystal growth process, so as to obtain a relatively flat or slightly convex growth interface shape, thereby preparing a large-size and high-quality InSb crystal with low defect density and uniform electrical parameters.

The following examples are given.

As shown in FIG. 1, in the embodiment of the invention, a backflow heat-insulating layer 9 which is obliquely downward is designed in a thermal field structure of a single crystal furnace, the backflow heat-insulating layer is made of high-purity quartz, and the cone angle inclination of the backflow heat-insulating layer is 45 degrees. The backflow heat insulation layer is positioned above the quartz crucible, one side of the backflow heat insulation layer is connected to the lifting device through a quartz fixing rod frame 10, the backflow heat insulation layer is similar to a seed rod which can move up and down, penetrates through a furnace wall and is connected with a lifting driving mechanism, and the rising and falling of the backflow heat insulation layer are achieved.

In the growth process of the InSb crystal 2, the power of the induction heating coil 3, the pulling rotation rate of the seed crystal 1 and the rotation rate of the graphite induction heating body 4 are accurately controlled according to technological parameters. By matching with the relative position movement of the backflow heat-insulating layer 9 and combining with the automatic regulation and control of the temperature of the crystallization area by the single crystal furnace temperature feedback system, the backflow heat-insulating layer 9 and the growth interface are in relative balance positions, good temperature gradient and ideal temperature distribution are obtained, the temperature fluctuation of the outer wall of the quartz crucible at the fixed distance of the crystal growth interface is ensured to be less than +/-0.1 ℃, and the environmental temperature fluctuation of the crystal low-temperature area at the fixed distance of the crystal growth interface is ensured to be less than +/-0.1 ℃, so that the problem of flexibly and effectively controlling the InSb crystal growth interface is fundamentally solved, and a result diagram of the InSb crystal growth interface applying the method is shown in figure 3, and is an obvious interface shape with a slightly convex middle and flat.

By means of the technical scheme of the embodiment of the invention, the method is obviously superior to the traditional regulation and control mode in the process of growing the InSb crystal by the pulling method, can flexibly and effectively control and regulate the thermal field fundamentally, can correspondingly and accurately regulate the position of the backflow heat-insulating layer according to the actual growth interface shape of different stages of crystal growth, obviously improves the convection condition, obtains good temperature gradient and ideal temperature distribution, further realizes effective control on the growth interface of the InSb crystal, obtains the relatively flat or slightly convex growth interface shape, and prepares the large-size and high-quality InSb crystal with low defect density and uniform electrical parameters.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. a single crystal furnace of InSb crystal growth, is characterized in that, comprises:

The reverse flow insulation layer is arranged above the quartz crucible, the reverse flow insulation layer is connected to the pulling device through a fixed rod frame, and the bottom end of the reverse flow insulation layer is inclined to the InSb in the middle of the quartz crucible at a certain taper angle. The crystal direction is tilted, which is used to adjust the corresponding position according to the actual growth interface shape at different stages of InSb crystal growth driven by the pulling device. During the growth of InSb crystal, the orientation shielding or Reflect a certain amount of radiant heat and change the thermal field structure of the single crystal furnace;

One end of the fixed rod frame is connected with the reverse flow insulation layer, and passes through the furnace wall of the single crystal furnace, and the other end is connected with the pulling device, which is used to drive the reverse flow insulation layer to move up and down under the driving of the pulling device;

The pulling device is connected to the reverse flow insulation layer through a fixed rod frame, and is used to drive the reverse flow insulation layer to move up and down through the fixed rod frame.

2. The single crystal furnace according to claim 1, wherein the pulling device specifically comprises:

Connecting bellows, one end is connected to the outside of the furnace wall where the fixed rod frame passes through, and the other end is connected to the airtight outer cover, and is sleeved on the outside of the fixed rod frame for telescopic movement driven by the lifting drive mechanism ;

An air-tight outer cover, connected with the connecting bellows, is used to ensure the vacuum state inside the single crystal furnace;

The lift driving mechanism is arranged in the airtight outer cover and connected with the fixed rod frame for driving the fixed rod frame to move up and down.

3 . The single crystal furnace according to claim 1 , wherein the backflow insulating layer is high-purity quartz. 4 .

4 . The single crystal furnace according to claim 1 , wherein the taper angle inclination is adjusted correspondingly according to crystals of different sizes grown. 5 .

5 . The single crystal furnace according to claim 1 , wherein the temperature of the crystallization zone is automatically adjusted by the temperature feedback system of the single crystal furnace to realize the adjustment of the relative equilibrium position of the backflow insulation layer and the InSb crystal growth interface. 6 .