阅读说明：本技术 一种九温区坩埚下降炉的结构设计 (Structural design of nine-temperature-zone crucible descending furnace ) 是由 刘欣 于 2020-07-09 设计创作，主要内容包括：本发明提供了一种九温区坩埚下降炉的结构设计,通过将九段温区化分为化料区、放肩区、等径生长区以及退火区,同时结合炉体内部的精确测温工艺,能够较为准确的监测晶体的生长过程,保证坩埚下降法生长晶体的稳定性和重复性。(The invention provides a structural design of a nine-temperature-zone crucible descent furnace, which is characterized in that the nine-temperature-zone crucible descent furnace is divided into a material melting zone, a shoulder-laying zone, an equal-diameter growth zone and an annealing zone, and meanwhile, the accurate temperature measurement process in a furnace body is combined, so that the growth process of crystals can be monitored more accurately, and the stability and the repeatability of the crystals grown by a crucible descent method are ensured.)

1. A nine-temperature-zone Bridgman furnace is characterized in that the nine-temperature-zone Bridgman furnace is divided into a material melting zone, a shoulder-laying zone, an equal-diameter zone and an annealing zone, and meanwhile, the growth process of crystals can be accurately monitored by combining an accurate temperature measurement process in a furnace body, so that the stability and the repeatability of the crystals grown by a Bridgman method are ensured; the nine-temperature-zone crucible lowering furnace specifically comprises: the device comprises an upper alumina heat-insulating structure (1), a quartz wafer (2), a quartz crucible (3), raw materials (4), a support shaft (5) capable of moving up and down, a metal heat-conducting rod (6) with cooling water introduced inside, an outer quartz tube (7), a heating furnace body (8), a detachable vacuum sealing element (9), an air outlet (10) and an air inlet (11); the quartz crucible (3) is used for containing raw materials (4), the supporting shaft (5) capable of moving up and down is used for fixing the quartz crucible (3), the center of the supporting shaft is provided with a metal heat conducting rod (6) with cooling water filled inside, and the upper end of the metal heat conducting rod (6) is aligned to the sharp opening of the quartz crucible (3), so that the latent heat of crystallization generated in the crystal growth process can be timely led out along a specific direction, and the growth of single crystals is facilitated; the quartz wafer (2) is arranged at the upper end of the quartz crucible (3) and is used for preventing the volatilization of the raw materials at high temperature; the quartz crucible (3) and the supporting shaft (5) which can move up and down are arranged inside the outer quartz tube (7), and the inner vacuum sealing is realized through a detachable vacuum sealing piece (9); the detachable vacuum sealing element (9) is provided with an air outlet (10) and an air inlet (11), so that the quartz can be vacuumized and filled with protective gas; the outer quartz tube (7) is arranged in a heating furnace body (8) with nine sections of independent heating temperature areas, and can heat the quartz crucible.

2. The nine-temperature-zone Bridgman furnace as claimed in claim 1, wherein the heating furnace body (8) is divided into four functional zones according to the characteristics of the Bridgman single crystal growth process, and is divided into a melting zone, a shouldering zone, an equal-diameter zone and an annealing zone according to the positions from top to bottom.

3. The nine-temperature-zone crucible lowering furnace according to claim 1, wherein the quartz crucible (3) is divided into a thin-mouth zone, a variable-diameter zone and an equal-diameter growth zone.

4. The nine-temperature-zone crucible lowering furnace as claimed in claim 2, wherein the temperature field range of the melting zone in the heating furnace body (8) comprises a temperature zone I, a temperature zone II and a temperature zone III, the upper end of the melting zone is higher than the upper end of the quartz crucible (3), the lower end of the melting zone is flush with the reducing part of the fine opening at the lower end of the quartz crucible (3), and after heating, the three temperature zones of the melting zone are set to be the same and are all higher than the melting point of the raw material by 5-10 ℃, so that the raw material is fully melted.

5. The nine-temperature-zone crucible lowering furnace as claimed in claim 2, wherein the temperature field range of the shouldering zone in the heating furnace body (8) is an IV temperature zone, the length of the temperature zone is slightly larger than that of the reducing zone of the quartz crucible (3), the length of the temperature zone of the IV temperature zone is 7-10cm, the temperature of the shouldering zone is lower than that of the melting zone, and the control of the temperature gradient of the shouldering zone can be realized by setting the heating temperature of the IV temperature zone, and the temperature gradient is 3-5 ℃/cm.

6. The nine-temperature-zone Bridgman furnace as claimed in claim 2, wherein the temperature field range of the inside constant diameter zone of the heating furnace body (8) is a V temperature zone and a VI temperature zone, the length of the temperature zone is slightly larger than that of the constant diameter growth zone of the quartz crucible (3), the length of the temperature zone is 10-20cm, the temperature of the inside constant diameter zone of the heating furnace body (8) is lower than that of the shouldering zone, and the control of the temperature gradient of the constant diameter zone can be realized by setting the heating temperature of the V temperature zone and the VI temperature zone, and the temperature gradient is 5-10 ℃/cm.

7. The nine-zone Bridgman furnace as claimed in claim 2, wherein the temperature fields of the annealing zone inside the heating furnace body (8) are VII, VIII and IX, the length of the temperature zone is about 1.5 times of the total length of the quartz crucible (3), the temperature of the annealing zone is the same as the lowest temperature of the constant diameter zone, and the temperatures of the three temperature zones of the annealing zone are set to be the same without temperature gradient.

8. The working process of the nine-temperature-zone crucible lowering furnace as claimed in any one of claims 1 to 7 comprises the following specific steps: according to the setting of a temperature field, the initial position of the quartz crucible (3) is positioned in a material melting area, seed crystals are placed at the narrow opening of the crucible, and heat preservation is carried out for 10 hours, so that the raw materials are fully melted and are in contact with the seed crystals; then the supporting shaft (5) begins to descend at the speed of 0.5-1mm/h, the crucible gradually enters a shouldering area, and crystals begin to grow by shouldering; when the crystal shouldering is finished, the crystal enters an equal-diameter area, the descending speed of the supporting shaft (5) is increased to 1-5mm/h, and the equal-crystal growth process of the crystal is realized; after the crystal growth is finished, entering an annealing area, stopping the descending of the supporting shaft (5), preserving heat for 10-30h, and performing stress relief annealing on the crystal; after the annealing is finished, all temperature areas are set for 10 hours and cooled to room temperature, and the crystal is taken out, so that the crystal growth process is finished; the crucible descending method needs to measure the position of the crucible, the length of each temperature zone, the size of the crucible and other parameters in advance, and can judge that the quartz crucible (3) is positioned at the accurate position in the furnace body at any time through the descending height difference of the supporting shaft (5).

Technical Field

The invention relates to a structural design of a crucible descending furnace, belonging to the field of semiconductor equipment manufacture.

Background

The crucible descending method is a commonly used single crystal growth process for preparing infrared optical crystals, scintillation crystals and the like, and the basic requirements of the process on equipment are that more than two heating temperature areas and the automatic lifting and rotating function of a crucible are required. At present, the number of temperature zones of a domestic Bridgman furnace is usually less than 5 (generally 3-4), the processes of seeding, shouldering and isodiametric growth of single crystals cannot be monitored in real time due to too few temperature zones, and the stability and the repeatability of a single crystal growth process are poor. Therefore, there is a strong need for a multiple temperature zone furnace that can monitor the crystal growth process in real time.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a structural design of a nine-temperature-zone crucible descent furnace, which is characterized in that the nine-temperature-zone crucible descent furnace is divided into a material melting zone, a shoulder-placing zone, an equal-diameter growth zone and an annealing zone, and meanwhile, the growth process of crystals can be monitored more accurately by combining an accurate temperature measurement process in a furnace body, so that the stability and the repeatability of the crystals grown by a crucible descent method are ensured.

The structure of the nine-temperature-zone crucible descending furnace is shown in figure 1, and specifically comprises an aluminum oxide upper heat insulation structure 1, a quartz wafer 2, a quartz crucible 3, raw materials 4, a supporting shaft 5 capable of moving up and down, a metal heat conducting rod 6 with cooling water introduced inside, an outer quartz tube 7, a heating furnace body 8, a detachable vacuum sealing element 9, a gas outlet 10 and a gas inlet 11. Wherein, the quartz crucible 3 is used for containing the raw material 4; the supporting shaft 5 capable of moving up and down is used for fixing the quartz crucible 3, the center of the supporting shaft is provided with the metal heat conducting rod 6 with cooling water filled inside, and the upper end of the metal heat conducting rod 6 is aligned to the sharp opening of the quartz crucible 3, so that the latent heat of crystallization generated in the crystal growth process can be timely led out along a specific direction, and the growth of single crystals is facilitated; the quartz wafer 2 is arranged at the upper end of the quartz crucible 3 and used for preventing the volatilization of the raw materials at high temperature; the quartz crucible 3 and the supporting shaft 5 which can move up and down are arranged inside the outer quartz tube 7, and the inner vacuum sealing is realized through a detachable vacuum sealing piece 9; the detachable vacuum sealing element 9 is provided with an air outlet 10 and an air inlet 11, so that the quartz can be vacuumized and filled with protective gas; the outer quartz tube 7 is arranged in a heating furnace body 8 with nine sections of independent heating temperature areas, and can realize heating of the quartz crucible.

Preferably, the heating furnace body 8 is divided into four functional areas according to the characteristics of the Bridgman method single crystal growth process, and divided into a material melting area, a shoulder area, an equal diameter area and an annealing area from top to bottom. The requirements of each functional area on the temperature field and the range of the temperature area are clearly specified.

Preferably, the structure of the quartz crucible 3 is schematically shown in fig. 2, and the quartz crucible 3 is divided into a thin-mouth region, a diameter-variable region and an equal-diameter growth region, which are designed according to the growth process of the crystal.

Preferably, the temperature field range of the material melting area in the heating furnace body 8 comprises a temperature area I, a temperature area II and a temperature area III, the upper end of the material melting area is higher than the upper end of the quartz crucible 3, the lower end of the material melting area is flush with the reducing part of the thin opening at the lower end of the quartz crucible 3, and after heating, the three temperature areas of the material melting area are set to be the same and are all higher than the melting point of the raw material by 5-10 ℃, so that the raw material is fully melted.

Preferably, the temperature field range of the shouldering area in the heating furnace body 8 is an IV temperature area, the length of the temperature area is slightly larger than the length of the reducing area of the quartz crucible 3, the length of the temperature area is preferably 7-10cm in general, the temperature of the shouldering area is lower than that of the material melting area, the control of the temperature gradient of the shouldering area can be realized by setting the heating temperature of the IV temperature area, and the temperature gradient is preferably 3-5 ℃/cm in general.

Preferably, the temperature field range of the inside constant diameter zone of the heating furnace body 8 is a V temperature zone and a VI temperature zone, the temperature zone length is slightly larger than the constant diameter growth zone length of the quartz crucible 3, the temperature zone length is preferably 10-20cm in general, the temperature of the inside constant diameter zone of the heating furnace body 8 is lower than the temperature of the shouldering zone, the temperature gradient of the constant diameter zone can be controlled by setting the heating temperature of the V temperature zone and the VI temperature zone, and the temperature gradient is preferably 5-10 ℃/cm in general.

Preferably, the temperature field range of the annealing zone inside the heating furnace body 8 is a VII temperature zone, a VIII temperature zone and an IX temperature zone, and the length of the temperature zones is about 1.5 times of the total length of the quartz crucible 3. The temperature of the annealing area is the same as the lowest temperature of the constant diameter area, and the temperature settings of the three temperature areas of the annealing area are the same without temperature gradient.

Preferably, the specific working process of the nine-temperature-zone crucible descending furnace is as follows: according to the setting of the temperature field, the initial position of the quartz crucible 3 is positioned in the material melting area, seed crystals are placed at the narrow opening of the crucible, and the temperature is kept for 10 hours, so that the raw materials are fully melted and are in contact with the seed crystals; then the supporting shaft 5 begins to descend at the descending speed of 0.5-1mm/h, the crucible gradually enters a shouldering area, and crystals begin to grow by shouldering; when the crystal shouldering is finished, the crystal enters an equal-diameter area, the descending speed of the supporting shaft 5 is increased to 1-5mm/h, and the equal-crystal growth process of the crystal is realized; after the crystal growth is finished, entering an annealing area, stopping the descending of the supporting shaft 5, preserving the heat for 10-30h, and performing stress relief annealing on the crystal; after the annealing is finished, all temperature areas are set for 10 hours to be cooled to the room temperature, and the crystal is taken out, so that the crystal growth process is finished. It should be noted that the crucible descending method requires measuring the position of the crucible, the length of each temperature zone, the size of the crucible, and other parameters in advance, and determining that the quartz crucible 3 is at the exact position inside the furnace body at any time through the height difference of the descending of the support shaft 5.

The invention has the beneficial effects that:

the nine-temperature-zone Bridgman furnace has the advantages that a, through the structural design of the nine-temperature-zone Bridgman furnace, the nine-temperature-zone Bridgman furnace is divided into a material melting zone, a shoulder-laying zone, an equal-diameter zone and an annealing zone, and meanwhile, the accurate temperature measurement process in the furnace body is combined, so that the growth process of crystals can be monitored accurately, and the stability and the repeatability of the crystals grown by the Bridgman method are ensured;

b the temperature field setting of the nine temperature zones is specially made according to the characteristics of the crystal growth process by the Bridgman method, and belongs to the original invention;

the nine-temperature-zone crucible lowering furnace is innovatively provided with the annealing zone in the crystal growth process, so that in-situ annealing can be directly performed after the crystal growth is finished, internal thermal stress is eliminated, and dislocation can be effectively reduced;

the nine-temperature-zone crucible lowering furnace is suitable for infrared crystals and scintillation crystals with melting points lower than 1000 ℃ and low saturated vapor pressure.

Drawings

FIG. 1 is a schematic view of a nine zone Bridgman furnace of the present invention;

FIG. 2 is a schematic structural view of the quartz crucible 3.

Reference numerals

1 heat preservation structure on the aluminium oxide, 2 quartzy disk, 3 quartz crucible, 4 raw materialss, 5 rotatable, the back shaft that reciprocates, the metal heat conduction stick of 6 inside logical cooling water, 7 outer quartz capsule, 8 heating furnace body, the sealing member can be dismantled to 9, 10 gas outlets, 11 air inlets.

Detailed Description

The invention is further illustrated by the following examples and figures.

The structure of a nine-temperature-zone crucible descent furnace is shown in the attached figure 1, and specifically comprises the following components: the device comprises an upper alumina heat-insulating structure 1, a quartz wafer 2, a quartz crucible 3, a raw material 4, a support shaft 5 capable of moving up and down, a metal heat-conducting rod 6 with cooling water introduced inside, an outer quartz tube 7, a heating furnace body 8, a detachable vacuum sealing element 9, an air outlet 10 and an air inlet 11; wherein, the quartz crucible 3 is used for containing the raw material 4; the supporting shaft 5 capable of moving up and down is used for fixing the quartz crucible 3, the center of the supporting shaft is provided with the metal heat conducting rod 6 with cooling water filled inside, and the upper end of the metal heat conducting rod 6 is aligned to the sharp opening of the quartz crucible 3, so that the latent heat of crystallization generated in the crystal growth process can be timely led out along a specific direction, and the growth of single crystals is facilitated; the quartz wafer 2 is arranged at the upper end of the quartz crucible 3 and used for preventing the volatilization of the raw materials at high temperature; the quartz crucible 3 and the supporting shaft 5 which can move up and down are arranged inside the outer quartz tube 7, and the inner vacuum sealing is realized through a detachable vacuum sealing piece 9; the detachable vacuum sealing element 9 is provided with an air outlet 10 and an air inlet 11, so that the quartz can be vacuumized and filled with protective gas; the outer quartz tube 7 is arranged in a heating furnace body 8 with nine sections of independent heating temperature areas, and can realize heating of the quartz crucible.

Preferably, the heating furnace body 8 is divided into four functional areas according to the characteristics of the Bridgman method single crystal growth process, and divided into a material melting area, a shoulder area, an equal diameter area and an annealing area from top to bottom. The requirements of each functional area on the temperature field and the range of the temperature area are clearly specified.

Preferably, the structure of the quartz crucible 3 is schematically shown in fig. 2, and the quartz crucible 3 is divided into a thin-mouth region, a diameter-variable region and an equal-diameter growth region, which are designed according to the growth process of the crystal.

Preferably, the temperature field range of the material melting area inside the heating furnace body 8 comprises a temperature area I, a temperature area II and a temperature area III, the upper end of the material melting area is higher than the upper end of the quartz crucible 3, the lower end of the material melting area is flush with the reducing part of the thin opening at the lower end of the quartz crucible 3, and after heating, the three temperature areas of the material melting area are set to be the same and are all higher than the melting point of the raw material by 10 ℃, so that the raw material is fully melted.

Preferably, the temperature field range of the shouldering area in the heating furnace body 8 is an IV temperature area, the length of the temperature area is slightly larger than the length of the reducing area of the quartz crucible 3, the length of the temperature area is preferably 8cm, the temperature of the shouldering area is lower than that of the melting area, the control of the temperature gradient of the shouldering area can be realized by setting the heating temperature of the IV temperature area, and the temperature gradient is preferably 3 ℃/cm.

Preferably, the temperature field range of the inside constant diameter zone of the heating furnace body 8 is a V temperature zone and a VI temperature zone, the temperature zone length is slightly larger than the constant diameter growth zone length of the quartz crucible 3, the preferred temperature zone length is 15cm, the temperature of the inside constant diameter zone of the heating furnace body 8 is lower than the temperature of the shouldering zone, the control of the temperature gradient of the constant diameter zone can be realized by setting the heating temperature of the V temperature zone and the VI temperature zone, and the preferred temperature gradient is 5 ℃/cm.

Preferably, the temperature field range of the annealing zone inside the heating furnace body 8 is a VII temperature zone, a VIII temperature zone and an IX temperature zone, and the length of the temperature zones is about 1.5 times of the total length of the quartz crucible 3. The temperature of the annealing area is the same as the lowest temperature of the constant diameter area, and the temperature settings of the three temperature areas of the annealing area are the same without temperature gradient.

Preferably, the specific working process of the nine-temperature-zone crucible descending furnace is as follows: according to the setting of the temperature field, the initial position of the quartz crucible 3 is positioned in the material melting area, seed crystals are placed at the narrow opening of the crucible, and the temperature is kept for 10 hours, so that the raw materials are fully melted and are in contact with the seed crystals; then the supporting shaft 5 begins to descend at the descending speed of 1mm/h, the crucible gradually enters a shouldering area, and crystals begin to grow in a shouldering mode; after the crystal shouldering is finished, the crystal enters an equal-diameter growth stage, the quartz crucible enters an equal-diameter area, the descending speed of the supporting shaft 5 is increased to 3mm/h, and therefore the equal-crystal growth process of the crystal is achieved; after the crystal growth is finished, entering an annealing area, stopping the descending of the supporting shaft 5, preserving the heat for 20 hours, and performing stress relief annealing on the crystal; after the annealing is finished, all temperature areas are set for 10 hours to be cooled to the room temperature, and the crystal is taken out, so that the crystal growth process is finished. It should be noted that the crucible descending method requires measuring the position of the crucible, the length of each temperature zone, the size of the crucible, and other parameters in advance, and determining that the quartz crucible 3 is at the exact position inside the furnace body at any time through the height difference of the descending of the support shaft 5.

The invention has the beneficial effects that:

the nine-temperature-zone Bridgman furnace has the advantages that a, through the structural design of the nine-temperature-zone Bridgman furnace, the nine-temperature-zone Bridgman furnace is divided into a material melting zone, a shoulder-laying zone, an equal-diameter zone and an annealing zone, and meanwhile, the accurate temperature measurement process in the furnace body is combined, so that the growth process of crystals can be monitored accurately, and the stability and the repeatability of the crystals grown by the Bridgman method are ensured;

b the temperature field setting of the nine temperature zones is specially made according to the characteristics of the crystal growth process by the Bridgman method, and belongs to the original invention;

the nine-temperature-zone crucible lowering furnace is innovatively provided with the annealing zone in the crystal growth process, so that in-situ annealing can be directly performed after the crystal growth is finished, internal thermal stress is eliminated, and dislocation can be effectively reduced;

the nine-temperature-zone crucible lowering furnace is suitable for infrared crystals and scintillation crystals with melting points lower than 1000 ℃ and low saturated vapor pressure.