A large-size VGF method germanium single crystal growth device and method

Abstract

This patent technology belongs to the field of compound semiconductor crystal growth, and specifically discloses a large-size VGF method germanium single crystal growth device and method, including a support system and a quartz ampoule, the quartz ampoule is placed on the support system, the support system includes an outer insulation layer, the outer insulation layer is provided with a first temperature control layer and a second temperature control layer on a cross section at a certain distance from the top and the bottom, the first temperature control layer and the second temperature control layer are respectively provided with three rectangular holes distributed in an array at an interval of 120°, the rectangular holes on the first temperature control layer and the six rectangular holes on the second temperature control layer are staggered and distributed in an array at an interval of 60°, the distance L between the first temperature control layer and the top of the outer insulation layer is equal to the distance L between the second temperature control layer and the bottom of the outer insulation layer, and the ratio coefficient between the outer diameter D and L of the outer insulation layer is 1.5, and the improved insulation and heat dissipation device can grow large-size, low-dislocation crystals.

Description

Technical Field

[0001] This patented technology belongs to the field of compound semiconductor crystal growth, and specifically relates to a large-size VGF method germanium single crystal growth device and method. Background Art

[0002] The VGF method (vertical gradient solidification method) has become the mainstream technology for growing large-size, low dislocation density crystals, but the required temperature gradient is getting lower and lower, and the requirements for the thermal field are getting higher and higher, so furnace preparation is very important, and the design of the furnace bottom support system and furnace jacket combination is crucial.

[0003] The support system provides support for the ampoule, and the low-density insulating material in the support system assembly hinders conduction and convection heating. The heat radiation channel penetrating the low-density material provides a path for heat radiation to enter and exit the seed well and transition zone of the crucible in the ampoule. The hollow core in the insulating material is directly below the seed well, providing cooling for the center of the growing crystal, which ensures the uniform and smooth growth of the crystal block and the smoothness of the interface between the crystal and the melt. In general, the crystallization latent heat generated during the crystal growth process is released by heat conduction and heat radiation through the hollow optical rod in the support system, thereby producing a disc with uniform electrical properties. However, for the growth of large-sized (6 inches and above) germanium single crystals, the growth process of germanium single crystals takes a long time, and there are defects such as crystallization latent heat and thermal stress that are difficult to release, which are prone to defects such as flower crystals and dense dislocations. Reasonable regulation of the temperature field to improve the crystal qualification rate is an important issue currently faced.

[0004] At the same time, after the crystal is formed, the quartz ampoule in the entire growth structure will experience crystallization and surface whitening, so the conventional method is to directly smash the quartz ampoule and then take out the crystal. This method makes the quartz ampoule unable to be used a second time, resulting in increased costs. Summary of the invention

[0005] The main purpose of the present invention is to provide a large-size VGF method germanium single crystal growth device and method to solve the problems that the crystallization latent heat and thermal stress of growing large-size crystals are difficult to release, and defects such as flower crystals and dense dislocations are easy to occur.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] A large-size VGF method germanium single crystal growth device comprises a support system and a quartz ampoule, wherein the quartz ampoule is placed on the support system, wherein the support system comprises a light guide rod, a furnace core, an inner quartz support tube, an inner insulation layer, an outer quartz support tube, and an outer insulation layer, wherein the quartz ampoule has a built-in lower crucible, a quartz middle ring, an upper crucible, and a quartz cap, wherein a first temperature control layer and a second temperature control layer are arranged on a cross section of the outer insulation layer at a certain distance from the top and the bottom, wherein three rectangular holes distributed in an array at intervals of 120° are arranged on the first temperature control layer and the second temperature control layer, respectively, wherein the rectangular holes on the first temperature control layer and the six rectangular holes on the second temperature control layer are staggered and distributed in an array at intervals of 60°, wherein a distance L between the first temperature control layer and the top of the outer insulation layer and a distance L between the second temperature control layer and the bottom of the outer insulation layer are equal, and a proportional coefficient between an outer diameter D of the outer insulation layer and L is 1.5.

[0008] Furthermore, insulation sleeves are respectively provided at the upper part of the rectangular hole on the first temperature control layer, the lower part of the rectangular hole on the second temperature control layer, and the middle part of the outer insulation layer.

[0009] Furthermore, the thickness of the insulation sleeve is 5 mm.

[0010] Furthermore, the material of the insulation cover is: rolled with high-temperature cement and wet felt, then dried indoors, and finally removed from excess moisture in a 1200°C oven;

[0011] The present invention also provides a method for using the device, comprising the following steps:

[0012] (1) First charging: After the lower crucible is filled with material, it is placed into the first section of quartz ampoule, and then the quartz middle ring is placed. The loaded upper crucible is then placed on the quartz middle ring, and then the quartz cap is placed on the upper crucible to seal it. Subsequently, the other part of the quartz ampoule is welded to the first section of the quartz ampoule by a trip welding method, and the entire assembly is placed in a furnace to evacuate the vacuum, and baked at 200°C. After the quartz middle ring, quartz cap and quartz ampoule are welded and bonded together with a hydrogen-oxygen flame, the quartz ampoule containing the material is placed in a single crystal furnace to grow single crystals;

[0013] (2) First unloading: After the single crystal growth is completed, the quartz ampoule is taken out, and the quartz ampoule is cut into sections along the first cutting edge at the junction of the quartz cap and the upper crucible and the second cutting edge formed by the welding portion after the quartz ampoule is welded in a sliding manner to form the first section quartz ampoule, the second section quartz ampoule, and the third section quartz ampoule. Then, the upper crucible and the lower crucible with the crystal are taken out, and the lower crucible with the crystal is immersed in a methanol solution to take out the crystal;

[0014] (3) Re-loading: After the lower crucible is filled with the material, it is placed into the first section quartz ampoule, and the first section quartz ampoule and the second section quartz ampoule are neatly welded together using a vertical welding method. The loaded upper crucible is then placed on the quartz middle ring, and then the cuts between the second section quartz ampoule and the third section quartz ampoule are neatly welded using a vertical welding method. After the welding is completed, it is placed for a period of time, and then the single crystal furnace is grown. In this way, the quartz ampoule can be reused.

[0015] The above technical solution of the present invention has the following beneficial technical effects: the improved heat preservation and heat dissipation device can grow large-sized, low-dislocation crystals. Through the use method of the present invention, the quartz ampoule can be reused 2 to 3 times, which can effectively reduce the production cost of each quartz ampoule to about RMB 800 to 1,300, and at the same time can reduce environmental pollution and waste of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of a germanium single crystal furnace;

[0017] Figure 2 The distribution diagram of rectangular holes in germanium single crystal is shown;

[0018] Figure 3 Distribution diagram of rectangular holes in the germanium single crystal insulation sleeve

[0019] Figure 4 The morphology of an 8-inch germanium single crystal ingot is shown in the figure;

[0020] Figure 5 Temperature distribution diagram of 8-inch germanium single crystal insulation cover before and after improvement;

[0021] Figure 6 Schematic diagram of the process of reusing quartz ampoules;

[0022] Among them: 1. light guide rod; 2. furnace core; 3. inner quartz support tube; 4. inner insulation layer; 5. outer quartz support tube; 6. outer insulation layer; 6-1, first temperature control layer; 6-2, second temperature control layer; 7. quartz ampoule; 8. quartz middle ring; 9. quartz cap; 10, lower crucible; 11, upper crucible; 12, rectangular hole; 13, insulation sleeve. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with embodiments and drawings.

[0024] Example 1

[0025] Design and production of 6-inch germanium single crystal growth

[0026] like Figure 1 and 2As shown, a 6-inch VGF method germanium single crystal growth device includes a support system and a quartz ampoule, the quartz ampoule is placed on the support system, the support system includes a light guide rod 1, a furnace core 2, an inner quartz support tube 3, an inner insulation layer 4, an outer quartz support tube 5, and an outer insulation layer 6, the quartz ampoule 7 has a lower crucible 10, a quartz middle ring 8, an upper crucible 11, and a quartz cap 9, and the outer insulation layer 6 is provided with a first temperature control layer 6-1 and a second temperature control layer 6-2 on a cross section at a certain distance from the top and the bottom, and the first temperature control layer Three rectangular holes 12 are arranged in an array with an interval of 120° on the first temperature control layer 6-1 and the second temperature control layer 6-2 respectively. The size of the rectangular holes is 20*70mm. The rectangular holes on the first temperature control layer 6-1 and the second temperature control layer 6-2 are 6 rectangular holes in total, which are arranged in an array with an interval of 60°. The distance L between the first temperature control layer 6-1 and the top of the outer insulation layer 6 is equal to the distance L between the second temperature control layer 6-2 and the bottom of the outer insulation layer 6, and the proportional coefficient between the outer diameter D of the outer insulation layer 6 and L is 1.5.

[0027] The inner quartz support tube has an outer diameter of 100mm, an inner diameter of 95mm, and a thickness of 2.5mm; the outer quartz support tube has an outer diameter of 140mm, an inner diameter of 130mm, and a thickness of 5mm;

[0028] Internal and external insulation layer: Use high-temperature cement and wet cotton to prepare the insulation tube, then dry it indoors, and finally remove excess moisture in a 1200℃ oven;

[0029] External insulation layer: outer diameter 175mm, inner diameter 140mm, thickness 17.5mm.

[0030] The temperature measurement zone setting during growth is consistent with patent CN201610495202.7.

[0031] The temperature control method for growing germanium single crystal includes four stages: heating melt, seed crystal welding, crystal growth, and crystal cooling, wherein:

[0032] The melting stage lasts for 43 hours. The first temperature zone is heated from 28°C to 880°C, the second temperature zone is heated from 28°C to 1014°C, the third temperature zone is heated from 28°C to 1015°C, the fourth temperature zone is heated from 28°C to 1015°C, the fifth temperature zone is heated from 28°C to 1027°C, and the sixth temperature zone is heated from 28°C to 1027°C;

[0033] Seed crystal welding stage, duration is 5 hours, slow cooling, the first temperature zone is cooled from 880℃ to 870℃, the second temperature zone is cooled from 1014℃ to 1005℃, the third temperature zone is cooled from 1015℃ to 1014.5℃, the fourth temperature zone is cooled from 1015℃ to 1014.5℃, the fifth temperature zone is cooled from 1027℃ to 1026.5℃, and the sixth temperature zone is cooled from 1027℃ to 1026.5℃;

[0034] During the crystal growth stage, the temperature was lowered in small steps. After about 175 hours, the first temperature zone was cooled from 870°C to 551°C, the second temperature zone was cooled from 1005°C to 712°C, the third temperature zone was cooled from 1014.5°C to 960°C, the fourth temperature zone was cooled from 1014.5°C to 1000°C, the fifth temperature zone was cooled from 1026.5°C to 1014°C, and the sixth temperature zone was cooled from 1026.5°C to 1016°C.

[0035] During the crystal cooling stage, the temperature is cooled down in stages to room temperature within 36 hours.

[0036] Specifically, a seed crystal of (100)0° of a germanium single crystal, a cone-shaped material, 54g of boron oxide, 17.5kg of a germanium ingot and about 1.451g of doped gallium are placed in a lower crucible, and then the lower crucible is placed flatly in a quartz ampoule 7, and a quartz middle ring 8 is placed in it. Then the cone-shaped material and the germanium ingot with doped gallium are placed in an upper crucible 11, and then they are placed flatly in a quartz ampoule 7 together and at the end, and finally a quartz cap 9 is placed in the end of the quartz ampoule 7. The entire assembly is placed in a baking oven to evacuate, bake at 200°C, and weld and bond the quartz middle ring, quartz cap and quartz ampoule together with a hydrogen-oxygen flame to achieve the purpose of sealing. Then the quartz ampoule containing the material is placed in a single crystal furnace to grow a single crystal. After the single crystal growth is completed, the crystal is taken out for parameter measurement.

[0037] like Figure 6 As shown, the first loading: after the lower crucible 10 is filled with the material, it is sent into the first section of the quartz ampoule, and then the quartz middle ring 8 is placed, and then the upper crucible 11 after the material is placed on the quartz middle ring, and then the quartz cap 9 is placed on the upper crucible 11 to cover it, and then the other part of the quartz ampoule is welded with the first section of the quartz ampoule by a trip welding method, and the whole assembly is placed in a furnace to evacuate, and baked at 200°C, and the quartz middle ring, quartz cap and quartz ampoule are welded and bonded together with a hydrogen-oxygen flame, and then the quartz ampoule filled with the material is placed in a single crystal furnace to grow a single crystal;

[0038] First unloading: After the single crystal growth is completed, the quartz ampoule is taken out, and the quartz ampoule is cut into sections along the first cutting edge at the junction of the quartz cap and the upper crucible and the second cutting edge formed by the welding part after the quartz ampoule is welded in a sliding manner to form the first section quartz ampoule, the second section quartz ampoule, and the third section quartz ampoule. Then the upper crucible and the lower crucible with the crystal are taken out, and the lower crucible with the crystal is immersed in a methanol solution to take out the crystal.

[0039] Re-loading: After filling the lower crucible with the material, send it into the first section quartz ampoule, use the vertical welding method, such as the welding method of patent 201921855524.3 to neatly weld the first section quartz ampoule and the second section quartz ampoule together, then place the loaded upper crucible on the quartz middle ring, and then use the vertical welding method to neatly weld the incisions between the second section quartz ampoule and the third section quartz ampoule. After the welding is completed, leave it for a period of time, and then carry out single crystal furnace growth. In this way, the quartz ampoule can be reused.

[0040] Through the above welding and cutting methods, the frequency of using the ampoule can be increased. Compared with the previous method of directly breaking the ampoule to obtain the crystal, the cost is greatly saved.

[0041] Example 2

[0042] Design and production of 8-inch germanium single crystal growth

[0043] The 8-inch VGF method germanium single crystal growth device is consistent with that in Example 1, except that the following settings are used:

[0044] The inner quartz support tube has an outer diameter of 111 mm, an inner diameter of 106 mm, and a thickness of 2.5 mm.

[0045] External quartz support tube: outer diameter 170mm, inner diameter 160mm, thickness 5mm;

[0046] External insulation layer: outer diameter 215mm, inner diameter 180mm, thickness 17.5mm.

[0047] Put the seed crystal of (100)0゜ of germanium single crystal, cone material, 54g of boron oxide, 20kg of germanium ingot and about 2.4g of doped gallium into the lower crucible, then put the lower crucible into the quartz ampoule bottle lying flat, put in the quartz middle ring 8, then put the cone material and the germanium ingot with doped gallium into the upper crucible, then put them into the quartz ampoule bottle lying flat together and at the end, and finally put the quartz cap into the end of the quartz ampoule bottle. Put the whole assembly into the oven to evacuate, bake at 200℃, and weld the quartz middle ring, quartz cap and quartz ampoule bottle together with hydrogen-oxygen flame to achieve the purpose of sealing. Then put the quartz ampoule bottle containing materials into the single crystal furnace to grow single crystal. After the single crystal growth is completed, take out the crystal for parameter measurement.

[0048] Example 3

[0049] Same as Example 2, except that Figure 3As shown, insulation sleeves 13 are respectively arranged in the middle of the outer insulation layer, the upper part of the rectangular hole on the first temperature control layer, and the lower part of the rectangular hole on the second temperature control layer. The outer diameter of the outer insulation layer plus the insulation sleeve is 220mm, the height of the upper and lower insulation sleeves is 85mm, and the height of the middle insulation sleeve is 40mm; the thickness of the insulation sleeve is 5mm.

[0050] The insulation cover is made of high-temperature cement and wet felt, then dried indoors, and finally in a 1200°C oven to remove excess moisture;

[0051] The gap between the thickness of the insulation sleeve and the outer quartz support tube is 10mm. On the basis of a certain degree of insulation, the heat flow can also be conducted out along the 6 rectangular holes.

[0052] The combination of the insulation sleeve and the outer insulation layer reduces the gap between the assembly and the inner wall of the furnace from the original 15mm to 10mm. Figure 5 As shown, the temperature gradient is smaller, the transition between the constant temperature zone, the large temperature gradient zone, and the small temperature gradient zone is smoother, and crystals with lower dislocations can be grown.

[0053] Put the seed crystal of (100)0° of germanium single crystal, cone material, 54g of boron oxide, 20kg of germanium ingot and about 2.4g of doped gallium into the lower crucible, then put the lower crucible into the quartz ampoule 7 lying flat, put in the quartz middle ring 8, then put the cone material and the germanium ingot with doped gallium into the upper crucible, then put them into the quartz ampoule 7 lying flat together and at the end, finally put the quartz cap into the end of the quartz ampoule 7. Put the whole assembly into the oven to evacuate, bake at 200℃, and weld the quartz middle ring, quartz cap and quartz ampoule together with hydrogen-oxygen flame to achieve the purpose of sealing. Then put the quartz ampoule containing materials into the single crystal furnace to grow single crystal. After the single crystal growth is completed, take out the crystal for parameter measurement.

[0054] Comparative Example 1

[0055] The outer insulation layer has no holes, and other settings are consistent with Example 1.

[0056] Comparative Example 2

[0057] The outer insulation layer has three holes, the second temperature control layer has two rectangular holes with a spacing of 120 degrees, the first temperature control layer has a rectangular hole and is placed between the two rectangular holes of the second temperature control layer, and the angle between the two adjacent rectangular holes on the same plane is 60 degrees. Other settings are consistent with Example 1.

[0058] It can be seen from Table 1 that in Example 1, Comparative Example 1 and Comparative Example 2, the temperature measurement values ​​are all empirical values ​​achieved by adjusting the control value. The temperature measurement values ​​of temperature measurement Tc1 to temperature measurement Tc6 of the three examples are relatively close, and the temperature gradients are also relatively close. The difference is mainly reflected in the different values ​​of temperature control 2. The temperature control 2 value of Example 1 is between Comparative Example 1 and Comparative Example 2, which is at a better value, which can ensure that a better growth rate is maintained during the crystal growth process. The crystal test results of the embodiment and the comparative example are shown in Table 2. The thermal insulation jacket of Comparative Example 1 is not perforated, and the result is that the single crystal rate is lower than that of Comparative Example 2 and Example 1, but the dislocation is better than that of Comparative Example 2. The perforation method of Example 1 ensures suitable insulation and heat dissipation effects, and the single crystal rate and dislocation are better than those of Comparative Example 1 and Comparative Example 2. The whole set of equipment of Example 2 is enlarged according to the ratio of the size ratio coefficient of Example 1 of 1.11 to 1.23. As the crystal size becomes larger, the single crystal rate and dislocation are significantly reduced. Example 3 By adding 3 insulation sleeves and 6 rectangular holes, the appearance of the 8-inch crystal is as follows: Figure 4 As shown in the figure, the temperature field distribution diagram of the 8-inch germanium single crystal insulation cover before and after improvement is as follows Figure 5 As shown, the present invention provides a good bottom thermal field for the growth of 8-inch single crystals, so that the single crystal rate is increased by about 4% and the dislocation is reduced by about 70%.

[0059]

Claims

1. A large-size VGF method germanium single crystal growth device, comprising a support system and a quartz ampoule, the quartz ampoule is placed on the support system, the support system comprises a light guide rod, a furnace core, an inner quartz support tube, an inner insulation layer, an outer quartz support tube, and an outer insulation layer, the quartz ampoule has a lower crucible, a quartz middle ring, an upper crucible, and a quartz cap built in, characterized in that: The first temperature control layer and the second temperature control layer are arranged on the cross section of the outer thermal insulation layer at a certain distance from the top and the bottom, and three rectangular holes arranged in an array with an interval of 120° are arranged on the first temperature control layer and the second temperature control layer respectively, and the rectangular holes on the first temperature control layer and the six rectangular holes on the second temperature control layer are staggered and arranged in an array with an interval of 60°, and the distance L between the first temperature control layer and the top of the outer thermal insulation layer and the distance L between the second temperature control layer and the bottom of the outer thermal insulation layer are equal, and the ratio coefficient between the outer diameter D of the outer thermal insulation layer and L is 1.5; The method for using the device comprises the following steps: (1) First charging: After the lower crucible is filled with material, it is placed into the first section of quartz ampoule, and then the quartz middle ring is placed. The loaded upper crucible is then placed on the quartz middle ring, and then the quartz cap is placed on the upper crucible to seal it. Subsequently, the other part of the quartz ampoule is welded to the first section of the quartz ampoule by a trip welding method, and the entire assembly is placed in a furnace to evacuate the vacuum, and baked at 200°C. After the quartz middle ring, quartz cap and quartz ampoule are welded and bonded together with a hydrogen-oxygen flame, the quartz ampoule containing the material is placed in a single crystal furnace to grow single crystals; (2) First unloading: After the single crystal growth is completed, the quartz ampoule is taken out, and the quartz ampoule is cut into sections along the first cutting edge at the junction of the quartz cap and the upper crucible and the second cutting edge formed by the welding portion after the quartz ampoule is welded in a sliding manner to form the first section quartz ampoule, the second section quartz ampoule, and the third section quartz ampoule. Then, the upper crucible and the lower crucible with the crystal are taken out, and the lower crucible with the crystal is immersed in a methanol solution to take out the crystal; (3) Re-loading: After the lower crucible is filled with the material, it is placed into the first section quartz ampoule, and the first section quartz ampoule and the second section quartz ampoule are neatly welded together using a vertical welding method. The loaded upper crucible is then placed on the quartz middle ring, and then the cuts between the second section quartz ampoule and the third section quartz ampoule are neatly welded using a vertical welding method. After the welding is completed, it is placed for a period of time, and then the single crystal furnace is grown. In this way, the quartz ampoule can be reused.

2. A large-size VGF method germanium single crystal growth device according to claim 1, characterized in that: The upper part of the rectangular hole on the first temperature control layer, the lower part of the rectangular hole on the second temperature control layer, and the middle part of the outer insulation layer are respectively provided with insulation sleeves.

3. A large-size VGF method germanium single crystal growth device according to claim 2, characterized in that: The thickness of the thermal insulation sleeve is 5 mm.

4. A large-size VGF method germanium single crystal growth device according to claim 3, characterized in that: The material of the thermal insulation sleeve is: rolled with high-temperature cement and wet felt, then dried indoors, and finally removed from excess moisture in a 1200°C oven.

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