High-purity antimony doping method without doping device

Abstract

The invention discloses a high-purity antimony doping method without a doping device, which specifically comprises the following steps: S1, melting: heating to melt prepared polycrystalline silicon into a liquid state in a quartz crucible; s2, temperature adjustment: gradually reducing the temperature of the molten silicon, and finally maintaining the temperature slightly higher than the crystallization temperature; s3, doping preparation: preparing doped materials, equipment and processes; and S4, doping: rapidly descending the combination of the heavy hammer, the high-purity antimony block and the seed crystal to complete doping operation. The method has the beneficial effects that the high-purity antimony is in a solid state before being immersed into the molten silicon, so that silicon splashing is avoided, and the loss of doped impurities is avoided; the loss of doped impurities is further reduced by adopting a measure of controlling evaporation after the high-purity antimony is immersed into the molten silicon; a doping device is omitted, so that the loss is lower; a proper amount of antimony blocks are prepared in advance, so that the time for mounting and dismounting the doping device is avoided, and the efficiency is improved; after doping, a seeding process can be quickly carried out, and no extra single crystal furnace preparation time is needed.

Description

Technical Field

[0001] The invention relates to the technical field of high-purity antimony doping, in particular to a high-purity antimony doping method without a doping device. Background Art

[0002] The commonly used doping methods for growing single crystal silicon by the Czochralski method can be classified into the eutectic method and the injection method. The eutectic method is to melt the doping material together with the polysilicon. The injection method is to inject the doping material into the molten silicon through certain measures after the polysilicon is completely melted to achieve the purpose of doping. The injection method is divided into gas phase doping, liquid phase doping and solid phase doping according to the state of the doping material when entering the molten silicon. All of them require corresponding doping equipment to achieve the purpose of doping. Because the evaporation coefficient of antimony oxide in silicon melt is relatively large, when using the eutectic method, the doping ratio of antimony element is less than 10%, and the doping ratio is too low, so the eutectic method is not applicable.

[0003] After searching the Chinese patent with announcement number CN202210603691, a doping method and device for MCZ method pulling heavily antimony-doped single crystals are disclosed. Due to the shielding and absorption of high temperature by multi-layer silicon wafers, complete solid-phase doping is close to being achieved. However, before the doping device is immersed in molten silicon, there is still a slight splash of silicon due to the melting and dripping of high-purity antimony particles, resulting in the loss of doping impurities. At the same time, the existence of the doping device will cause two kinds of losses. One is the loss of the doping device itself, and the other is the operating time loss caused by its installation and removal and the single crystal furnace preparation time loss.

[0004] In summary, it can be seen that the existing high-purity antimony doping process requires the use of corresponding doping devices, which leads to reduced doping efficiency and various losses, such as the loss of doping impurities caused by silicon sputtering, the loss of doping devices, and the delay in installing and removing doping devices. Summary of the invention

[0005] The object of the present invention is to provide a high-purity antimony doping method without the need for a doping device, so as to solve the problems raised in the above background technology.

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

[0007] A high-purity antimony doping method without a doping device specifically comprises the following steps:

[0008] S1. Melt: Heat and melt the prepared polysilicon into liquid in a quartz crucible;

[0009] S2, temperature adjustment: gradually reduce the heating power to gradually reduce the temperature of the molten silicon, and finally maintain it slightly higher than the crystallization temperature;

[0010] S3, doping preparation: select a combination of a high-purity antimony block and a seed crystal of appropriate weight, place a hollow silicon wafer sleeve on top of the high-purity antimony block, and hang the combination on a heavy hammer; then purify the auxiliary chamber of the single crystal furnace;

[0011] S4. Doping: Continue to adjust the temperature inside the single crystal furnace, control the temperature to be higher than the crystallization temperature and close to the crystallization temperature, open the isolation valve between the main chamber and the auxiliary chamber of the single crystal furnace, quickly lower the combination of the heavy hammer, high-purity antimony block and seed crystal, and immerse the high-purity antimony block in the molten silicon to complete the doping operation; after doping is completed, the temperature of the molten silicon is suitable to quickly start seeding and single crystal growth.

[0012] As a preferred solution of the present invention: the diameter of the hollow silicon wafer in S1 is controlled to be 100-160 mm, and the thickness is controlled to be 1-2 mm.

[0013] As a preferred solution of the present invention: during the doping process of S4, the furnace pressure in the single crystal furnace is controlled to be 10-50 Torr higher than the process furnace pressure.

[0014] As a preferred solution of the present invention: during the doping process of S4, the speed of crystal rise and fall in the single crystal furnace is increased so that the time taken for high-purity antimony to fall from the beginning to immerse in molten silicon is less than 4 minutes.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. High-purity antimony is in solid state before being immersed in molten silicon, and there is no silicon splashing, which avoids the loss of doped impurities;

[0017] 2. Measures to control evaporation of high-purity antimony after immersion in molten silicon to further reduce the loss of doped impurities;

[0018] 3. Eliminate doping device, lower loss;

[0019] 4. Prepare the right amount of antimony blocks in advance, eliminating the time required to install or remove the doping device, thus improving efficiency;

[0020] 5. After doping, the production process can be quickly entered without additional single crystal furnace preparation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a flow chart of the method. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] See also Figure 1 , the present invention provides a technical solution:

[0024] A high-purity antimony doping method without a doping device specifically comprises the following steps:

[0025] S1. Melt: Heat and melt the prepared polysilicon into liquid in a quartz crucible;

[0026] S2, temperature adjustment: gradually reduce the heating power to gradually reduce the temperature of the molten silicon, and finally maintain it slightly higher than the crystallization temperature;

[0027] S3, doping preparation: select a combination of a high-purity antimony block and a seed crystal of appropriate weight, place a hollow silicon wafer sleeve on top of the high-purity antimony block, and hang the combination on a heavy hammer; then purify the auxiliary chamber of the single crystal furnace;

[0028] S4. Doping: Continue to adjust the temperature inside the single crystal furnace, control the temperature to be higher than the crystallization temperature and close to the crystallization temperature, open the isolation valve between the main chamber and the auxiliary chamber of the single crystal furnace, quickly lower the combination of the heavy hammer, high-purity antimony block and seed crystal, and immerse the high-purity antimony block in the molten silicon to complete the doping operation; after doping is completed, the temperature of the molten silicon is suitable to quickly start seeding and single crystal growth.

[0029] Furthermore, the diameter of the hollow silicon wafer in S1 is controlled to be 100-160 mm, and the thickness is controlled to be 1-2 mm.

[0030] Furthermore, during the doping process of S4, the furnace pressure in the single crystal furnace is controlled to be 10-50 Torr higher than the process furnace pressure.

[0031] Furthermore, during the doping process of S4, the speed of the single crystal furnace crystal rise and fall is increased, so that the time taken for the high-purity antimony to be dropped from the beginning to the immersion in the molten silicon is less than 4 minutes.

[0032] Specifically, when this method is executed, the specific steps are:

[0033] S1. Melt: Heat and melt the prepared polysilicon into liquid in a quartz crucible;

[0034] S2, temperature adjustment: gradually reduce the heating power to gradually reduce the temperature of the molten silicon, and finally maintain it slightly higher than the crystallization temperature;

[0035] S3, doping preparation: select a combination of high-purity antimony block and seed crystal of appropriate weight, put the hollow silicon wafer on the top of the high-purity antimony block, and hang the combination on a heavy hammer; then purify the auxiliary chamber of the single crystal furnace. Because the bottom of the high-purity antimony block is a smooth arc, the reflected heat can slow down its melting speed; such a hollow silicon wafer can float in the center of the molten silicon surface after the high-purity antimony block is immersed in molten silicon, and it will slowly melt after slight crystallization, which plays a shielding role and can avoid silicon splashing;

[0036] S4. Doping: Control the temperature in the single crystal furnace to be higher than the crystallization temperature and close to the crystallization temperature to avoid high-temperature baking. Maintain the temperature at the center of the molten silicon surface slightly higher than the crystallization temperature, thereby reducing the amount of heat radiation and saving the temperature adjustment time. The seeding and single crystal growth can be started faster. The time saving can also reduce the total amount of evaporation. After the temperature adjustment is completed, the furnace pressure in the single crystal furnace is controlled to be 10-50Torr higher than the process furnace pressure to further reduce the evaporation rate. Then start the doping operation. During the doping process, increase the speed of the single crystal furnace crystal rise and fall, so that the time taken from the beginning of the fall to the immersion in the molten silicon is less than 4 minutes. This can increase the doping rate and ensure the solid form of the high-purity antimony before it is immersed in the molten silicon.

[0037] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-purity antimony doping method without a doping device, characterized in that: The specific steps include: S1. Melt: Heat and melt the prepared polysilicon into liquid in a quartz crucible; S2, temperature adjustment: gradually reduce the heating power to gradually reduce the temperature of the molten silicon, and finally maintain it slightly higher than the crystallization temperature; S3, doping preparation: select a combination of a high-purity antimony block and a seed crystal of appropriate weight, place a hollow silicon wafer sleeve on top of the high-purity antimony block, and hang the combination on a heavy hammer; then purify the auxiliary chamber of the single crystal furnace; S4. Doping: Continue to adjust the temperature inside the single crystal furnace, control the temperature to be higher than the crystallization temperature and close to the crystallization temperature, open the isolation valve between the main chamber and the auxiliary chamber of the single crystal furnace, quickly lower the combination of the heavy hammer, high-purity antimony block and seed crystal, and immerse the high-purity antimony block in the molten silicon to complete the doping operation; after doping is completed, the temperature of the molten silicon is suitable to quickly start seeding and single crystal growth.

2. A high-purity antimony doping method without a doping device according to claim 1, characterized in that: The diameter of the hollow silicon wafer in S3 is controlled to be 100-160 mm, and the thickness is controlled to be 1-2 mm.

3. The high-purity antimony doping method without a doping device according to claim 1, characterized in that: During the doping process of S4, the furnace pressure in the single crystal furnace is controlled to be 10-50 Torr higher than the process furnace pressure.

4. The high-purity antimony doping method without a doping device according to claim 1, characterized in that: During the doping process of S4, the speed of the single crystal furnace crystal rise and fall is increased, so that the time taken for the high-purity antimony to fall from the beginning to immerse in the molten silicon is less than 4 minutes.

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