CN219218218U

CN219218218U - Crystal growth device with heating cover

Info

Publication number: CN219218218U
Application number: CN202320056115.7U
Authority: CN
Inventors: 张鑫; 史艳磊; 孙聂枫; 王书杰; 康永; 赵红飞; 李亚旗; 邵会民; 张晓丹; 刘惠生
Original assignee: CETC 13 Research Institute
Current assignee: CETC 13 Research Institute
Priority date: 2023-01-09
Filing date: 2023-01-09
Publication date: 2023-06-20
Anticipated expiration: 2033-01-09

Abstract

A crystal growth device with a heating cover relates to the field of crystal preparation and comprises a furnace body, a crucible in the furnace body, a seed rod, a movable crystal heating cover and a quartz observation window at the top of the furnace body, wherein the movable crystal heating cover consists of a symmetrical left cover body and a symmetrical right cover body, and the left cover body and the right cover body are combined to form a cylindrical heating cover with a top sealed and a lower opening. By adopting the equipment provided by the utility model, the temperature gradient in the crystal can be reduced in the crystal growth process and the cooling process after the crystal is lifted, so that the crystal stress is reduced, the stability of the crystal growth process is ensured, and the crystal yield is ensured; the heat preservation cover is arranged separately, the heat preservation cover is arranged at the side edge of the crucible in the initial stage of crystal growth, the establishment of a thermal field in the seeding shoulder stage is facilitated, the obstruction to convection in the furnace body is reduced, and meanwhile, observation through the observation window is facilitated.

Description

Crystal growth device with heating cover

Technical Field

The utility model relates to the field of crystal preparation, in particular to a crystal growth device for preparing a crystal belt heating cover by using a pulling method.

Background

The pulling method is a method for growing crystal from melt, is a common growth method for semiconductor crystal, optical crystal and the like, and has the characteristics of high yield, high growth speed, easy observation and the like.

Pulling methods are commonly used with single heater growth. In the pulling method, the crystal is pulled out of the melt, especially when the crystal is pulled to a higher position, part of the crystal which is pulled out first can be cooled to a lower temperature due to lower ambient temperature. The temperature at the crystal growth solid-liquid interface is maintained near the crystal melting point, so that, assuming that the longitudinal temperature distribution in the crystal is linear, the gradient in the crystal is about equal to (T-T table)/L, L being the distance from the crystal growth solid-liquid interface to the crystal surface, T being the crystal surface temperature, T being the temperature at the crystal growth solid-liquid interface (about the melting point temperature of the crystal). During steady state growth, the T-boundary is approximately equal to the melting point temperature of the crystal, approximately a fixed value. The main way to reduce the crystal temperature gradient is to raise the crystal surface temperature T-table. The temperature of the pulled crystal is kept and heated, so that the temperature gradient of the surface of the crystal is improved.

Currently, the main stream is to add a thermal insulation cover and a post-heater above the crucible and the crystal, for example, chinese patent application 201810509188.0 discloses a crystal growing device of celio 3 by the pulling method and a control method thereof. However, although this method has a heat-insulating effect on the crystal to some extent, it has a great disadvantage in practical application. Firstly, the heater and the cover above cover the whole crucible body, so that the temperature gradient of the melt is reduced, the crystal is easy to destabilize in the growth process, and the crystal is twinned, and is even crystallized. Especially in the early stage of crystal growth (seeding and shouldering stage), the crystal is in the central area of the melt with lower temperature gradient, the growth is unstable, and the crystal is easy to be crystallized. And, when the method is used for growing compound crystals containing volatile elements (such as indium phosphide, gallium arsenide, gallium phosphide, indium arsenide, indium antimonide, gallium antimonide, zinc germanium phosphide and the like), the post heater heats the crystals, which can cause dissociation of the crystals, i.e. volatilization of the volatile elements into the atmosphere. The degree of dissociation of the crystals is severe, which may render the crystals unusable. Therefore, the power of the post heater is limited by using such thermal field to grow compound crystals of volatile elements.

Chinese patent application 200910112711.7 discloses a method and apparatus for growing large-size sodium yttrium tungstate crystals by a two-stage heating pulling method, which is also provided with two fixed heating mechanisms for heating the crucible and the pulled crystals, respectively. However, the device is in an open state right above the crystal, so that heat dissipation is serious, the heat preservation effect on the crystal is not strong, and the effect of reducing stress is not obvious. Particularly for crystals containing volatile elements, the dissociation phenomenon will be very severe in a relatively open environment by the heated crystals. For some materials with higher growth ambient pressure, the high pressure air flow will have a strong heat dissipation effect on the unsealed crystal, thereby reducing the heating effect of the post heater.

Chinese patent application 201910631648.1 discloses a coil movable type temperature field structure suitable for a pulling method and a single crystal growth method, and adopts a technical scheme that a rear heating cylinder is arranged above a crucible, and the crucible and the rear heating cylinder are respectively heated by moving a heating coil. The device uses the external moving coil, can heat the crucible and the rear heating cylinder simultaneously, has power interference between the crucible and the rear heating cylinder, and has low control precision. The crystal growth has high requirement on the stability of the temperature in the crucible, the movement of the coil for heating the crucible can greatly affect the thermal field, and the heating cylinder is used for sensing, so that the coil power is split, the large-range fluctuation of the temperature gradient of the melt is easily caused, and the crystal growth failure is caused. And the relative position of the heat preservation cylinder and the crystal is far, and the rear heating barrel has a heating effect on the whole environment, so that the whole environment including the temperature gradient in the melt can be reduced, and the crystal growth can be caused to have lower stability. The coil device respectively heats the melt and the crystal in the cooling process of the crystal growth end, has no obvious heat preservation and heating effects on the crystal in the crystal growth process, and has no obvious improvement effects on the defects of stress, dislocation and the like generated by the temperature difference of the upper end and the lower end of the crystal in the crystal growth process.

To solve the above problems, the applicant proposed a low stress crystal growth method (CN 112746312A), in which a "crystal growth apparatus by the pulling method of a movable crystal heating mantle" is disclosed, in which the heating mantle body of the movable crystal heating mantle is integrated, placed over a crucible, and covered with the movable crystal heating mantle after the crystal is pulled out of the melt.

In practice, the applicant has found that the above structure has the following problems: the heat-insulating cover positioned above has a larger blocking effect on convection in the furnace body before descending.

Disclosure of Invention

The present utility model has been made to overcome the above-described problems.

In order to achieve the above purpose, the present utility model adopts the following technical scheme: the utility model provides a take crystal growing device of heating mantle, includes the furnace body, arranges crucible and heater, seed pole, seed chuck, seed pole drive arrangement, portable crystal heating mantle in the furnace body in, arranges the quartz observation window at furnace body top in, and the key lies in, portable crystal heating mantle comprises symmetrical left cover body, right cover body, connects left drive arrangement and right drive arrangement respectively, and left drive arrangement and right drive arrangement drive left cover body and right cover body and merge, form the sealed lower part open-ended cylinder heating mantle in top.

Further, the left driving device and the right driving device are respectively connected with the left cover body and the right cover body through a left connecting rod and a right connecting rod.

Further, the left driving device and the right driving device drive the left connecting rod and the right connecting rod to rotate left and right and move up and down.

Further, the tops of the left cover body and the right cover body are respectively provided with a left semicircular notch and a right semicircular notch, and after the left cover body and the right cover body are combined, the diameter of a round hole formed by the left semicircular notch and the right semicircular notch is larger than that of the seed crystal rod.

By adopting the equipment provided by the utility model, the temperature gradient in the crystal can be reduced in the crystal growth process and the cooling process after the crystal is lifted, so that the crystal stress is reduced, the stability of the crystal growth process is ensured, and the crystal yield is ensured; the heat preservation cover is arranged separately, the heat preservation cover is arranged at the side edge of the crucible in the initial stage of crystal growth, the establishment of a thermal field in the seeding shoulder stage is facilitated, the obstruction to convection in the furnace body is reduced, and meanwhile, observation through the observation window is facilitated.

Drawings

Figure 1 is a schematic diagram of the equipment composition,

figure 2 is a state diagram of the apparatus at the initial stage of crystal growth,

figure 3 is a state diagram of the device after the heat shields are combined and lowered,

fig. 4 is a state diagram of the apparatus after the completion of the crystal growth.

Wherein, 1 is a furnace body, 2 is a crucible, 3 is a heater, 4 is a seed rod, 5 is a seed chuck, 6 is a seed rod driving device, 7 is a quartz observation window, 8-1 is a left cover body, 8-2 is a right cover body, 9-1 is a left driving device, 9-2 is a right driving device, 10-1 is a left connecting rod, 10-2 is a right connecting rod, 11-1 is a left semicircular notch, 11-2 is a right semicircular notch, 12 is a seed crystal, 13 is a metal melt, 14 is a covering agent, and 15 is a crystal.

Detailed Description

The utility model is further described below with reference to the accompanying drawings.

A crystal growing apparatus with a heating mantle, see fig. 1. Fig. 1 comprises two diagrams, the upper one being a front cross-sectional view of the apparatus and the lower one being a top view of the interior of the furnace body 1. The growth equipment comprises a furnace body 1, a crucible 2 arranged in the furnace body 1, a heater 3 arranged around the crucible, a heat insulation layer arranged around the heater 3, a seed rod 4, a seed chuck 5 and a seed rod driving device 6, wherein a seed crystal 12 is arranged on the seed chuck, and the seed rod driving device 6 is opposite to the central position of the crucible 2 and drives the seed crystal 12 to move up and down; the growth device also comprises a quartz observation window 7 arranged at the top of the furnace body 1, and a movable crystal heating cover is arranged in the furnace body 1.

The key point of the utility model is that the movable crystal heating cover is divided into a left cover body 8-1 and a right cover body 8-2, the left cover body 8-1 and the right cover body 8-2 are respectively connected with a left driving device 9-1 and a right driving device 9-2, and the left driving device 9-1 and the right driving device 9-2 drive the left cover body 8-1 and the right cover body 8-2 to be combined to form a cylindrical heating cover with a top sealed and a lower opening.

The left driving device 9-1 and the right driving device 9-2 are respectively connected with the left cover body 8-1 and the right cover body 8-2 through a left connecting rod 10-1 and a right connecting rod 10-2, and the left driving device 9-1 and the right driving device 9-2 drive the left connecting rod 10-1 and the right connecting rod 10-2 to rotate left and right and move up and down.

In the prior application of the applicant, the heating cover is positioned right above the crucible and has a great blocking effect on convection in the furnace body before descending, and in the initial stage of crystal growth, referring to fig. 1 and 2, the left cover body 8-1 and the right cover body 8-2 are arranged on two sides above the furnace body 1 and are also the side positions of the crucible 2, so that the establishment of a thermal field in the seeding shouldering stage is facilitated.

Meanwhile, the heat preservation cover is positioned beside the crucible, which is more beneficial to observation. Because the observation window of the barrel-shaped high-pressure furnace is often arranged on the furnace top, in the barrel-shaped furnace with the same length, the diameter and the length of the heat preservation cover arranged above the crucible are limited greatly, and the upper limit value of the diameter and the length can be increased when the heat preservation cover is arranged on the side surface.

The left cover 8-1 and the right cover 8-2 are combined to surround the seed rod 4. In order to tightly combine the two cover bodies, a left semicircular notch 11-1 and a right semicircular notch 11-2 are respectively arranged at the top parts of the left cover body 8-1 and the right cover body 8-2, and after the left cover body 8-1 and the right cover body 8-2 are combined, the diameter of a round hole formed by the left semicircular notch 11-1 and the right semicircular notch 11-2 is larger than the diameter of the seed crystal rod 4. The combined device state is shown in fig. 3.

The diameter of the round shape formed after combination is 2mm larger than the diameter of the seed rod 4, the inside of the heating cover is communicated with the inside of the furnace body 1, and the pressure is kept basically the same.

The working process of the equipment comprises the following steps:

the crucible 2 is internally provided with raw materials and covering agents, the seed crystal 12 is arranged on the seed crystal chuck 5, the left driving device 9-1 and the right driving device 9-2 drive the left cover body 8-1 and the right cover body 8-2 to ascend and rotate through the left connecting rod 10-1 and the right connecting rod 10-2, and the left cover body 10-1 and the right cover body 8-2 are arranged at the side surface of the upper part in the furnace body 1.

The heater 3 is turned on for a period of time until the raw material and the covering agent in the crucible 2 are melted, and the covering agent covers the raw material melt due to the lower density than the raw material, as shown in fig. 1.

The raw materials can be indium phosphide, gallium arsenide, gallium phosphide, indium arsenide, indium antimonide, gallium antimonide, zinc germanium phosphide and the like.

The seed rod driving device 6 drives the seed rod 4 to descend until the seed crystal 12 contacts the surface of the metal melt 13, and if the temperature of the metal melt 13 is suitable for crystal growth, the contact position of the seed crystal 12 and the metal melt 13 gradually grows to become a crystal 15 after contact, as shown in fig. 2.

When the crystal grows to a required diameter, the left driving device 9-1 and the right driving device 9-2 drive the left cover body 8-1 and the right cover body 8-2 to be combined to form a cylindrical heating cover with a top sealed and an opening at the lower part, and the cylindrical heating cover descends, so that the lower edge of the cylindrical heating cover is immersed in the covering agent 14, as shown in fig. 3.

The "required diameter" is about +5mm of the standard wafer size. If crystals with the target diameter of 2 inches are manufactured, the required diameter is 55.8 mm; a target diameter of 3 inch crystals, a desired diameter of 81.2 mm; a target diameter of 4 inch crystals, a desired diameter of 105mm; the target diameter was 6 inch crystals and the desired diameter was 155mm.

In the prior application of the applicant, a heating wire is arranged outside the heating cover, a phosphorus source box is arranged in the heating cover, the heating wire has the functions of 1, keeping the temperature in the heating cover, 2, gasifying elements in the phosphorus source box, and ensuring that grown crystals are not dissociated.

In the utility model, the heating device is not arranged around the heating cover, and the inside of the heating cover is also not provided with the phosphorus source box.

With the apparatus of the present utility model, when the crystal starts to grow, the left and right shields 8-1 and 8-2 are placed at the upper side positions in the furnace body 1, the convection of the gas is not hindered, and the temperature in the space above the crucible 2 in the furnace body 1 is maintained substantially uniform. After being combined into a cylindrical heating cover, the internal temperature of the heating cover is consistent with the external temperature, the crystal is covered after the temperature is reduced, and the temperature in the heating cover can be kept by the crystal, so that a heating device is not needed.

The crystal dissociates a portion of the gas at high temperature, such as indium phosphide dissociates a portion of the phosphorus gas, which acts to inhibit further dissociation of the crystal within the heating mantle.

At the beginning, the upper surface of the crystal is dissociated, phosphorus gas is released, and the gas is seldom escaped due to the basic sealing of the heating cover, and when reaching a certain concentration, the effect of inhibiting the further dissociation of the crystal is achieved.

The crystal is polished during further processing, and the surface layer which is understood can be removed, so that the inherent quality of the crystal is not affected.

During crystal growth, it is preferable to keep the lower edge of the cylindrical heating mantle immersed in the covering agent 14 at all times.

The crystal 15 is pulled to a position satisfying the weight, the crystal 15 and the heating mantle are pulled rapidly, the crystal 15 is lifted out of the metal melt 13 and the boron oxide 14, and the crystal 15 is placed in the heating mantle as shown in fig. 4.

Cooling, disassembling the furnace, and taking out the crystal.

Claims

1. The utility model provides a take crystal growing device of heating mantle, includes furnace body (1), crucible (2) and heater (3), seed pole (4), seed chuck (5), seed pole drive arrangement (6), portable crystal heating mantle, the quartz observation window (7) of arranging in furnace body (1) top in placing in furnace body (1) in, its characterized in that, portable crystal heating mantle comprises symmetrical left cover body (8-1), right cover body (8-2), connects left drive arrangement (9-1) and right drive arrangement (9-2) respectively, and left drive arrangement (9-1) and right drive arrangement (9-2) drive left cover body (8-1) and right cover body (8-2) merge, form the sealed lower open-ended cylinder heating mantle in top.

2. Crystal growth apparatus according to claim 1, wherein the left and right driving means (9-1, 9-2) are connected to the left and right housings (8-1, 8-2) by left and right connecting rods (10-1, 10-2), respectively.

3. The crystal growing apparatus according to claim 2, wherein the left driving means (9-1) and the right driving means (9-2) drive the left connecting rod (10-1) and the right connecting rod (10-2) to rotate left and right and move up and down.

4. The crystal growing apparatus according to claim 1, wherein the top parts of the left cover body (8-1) and the right cover body (8-2) are respectively provided with a left semicircular notch (11-1) and a right semicircular notch (11-2).

5. The crystal growth apparatus according to claim 4, wherein the diameter of the round hole formed by the left semicircular notch (11-1) and the right semicircular notch (11-2) is larger than the diameter of the seed rod (4) after the left cover body (8-1) and the right cover body (8-2) are combined.

6. The crystal growing apparatus according to claim 5, wherein the diameter of the circular shape is 2mm larger than the diameter of the seed rod (4).