CN115928195A - Method for improving seeding process - Google Patents
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- CN115928195A CN115928195A CN202210759157.7A CN202210759157A CN115928195A CN 115928195 A CN115928195 A CN 115928195A CN 202210759157 A CN202210759157 A CN 202210759157A CN 115928195 A CN115928195 A CN 115928195A
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Abstract
The invention provides a method for improving a seeding process, which comprises the steps of calculating the standard length of fine crystal containing dislocation before seeding; calculating actual fine grain length according to the standard length of fine grains; seeding: seeding is carried out according to the actual fine grain length. The method has the advantages that the actual seeding length is shortened through calculation, so that the seeding length is more reasonable, the seeding time is shorter, dislocation is effectively eliminated, the seeding time is saved, and the seeding efficiency is improved.
Description
Technical Field
The invention belongs to the technical field of silicon single crystal manufacturing, and particularly relates to a method for improving a seeding process.
Background
In the process of pulling the silicon single crystal, when the seed crystal is inserted into a melt, because the temperature difference between the seed crystal and the silicon melt is large, the high-temperature silicon melt causes strong thermal shock to the seed crystal, and a large amount of dislocation is generated at the head of the seed crystal. In order to eliminate dislocations in the pulled-out single crystal, necking (pulling fine crystal) is started after completion of the fusion. According to the prior seeding process, the neck is generally reduced to a diameter of 3-5mm, so that the thermal stress is small during cooling and no dislocation is generated.
The seeding time and the seeding length in the existing seeding process are large, dislocation in seed crystals can be completely eliminated when the dislocation is in a certain length in the seeding process, but the existing process still continues seeding, so that the waste of time is caused.
Disclosure of Invention
In view of the above, the present invention provides a method for improving seeding process to solve the above or other problems in the prior art.
In order to solve the technical problems, the invention adopts the technical scheme that: a method for improving seeding technology includes,
calculating a standard length of dislocation-containing fine crystals prior to seeding;
calculating actual fine grain length according to the standard length of fine grains;
seeding is carried out: seeding is carried out according to the actual fine grain length.
Further, when the standard length of the fine crystal grains containing dislocations is calculated, the calculation is performed using the following formula:
L＝d*ctgα+A
wherein L is the length of the dislocation-containing fine crystal, d is the diameter of the fine crystal, alpha is the included angle between the dislocation line and the growth direction, and A is the correction length.
Further, the dislocation line included an angle of 54 ° 44' with the direction of crystal growth.
Further, the correction length is 20-30mm.
Further, the modified length a = m + n, where m is the transition stage length between the seed crystal and the fine crystal, and n is the transition stage length between the fine crystal and the crystal.
Furthermore, the diameter of the fine crystal is 4-6mm.
Further, the actual fine grain length is a difference between the preset fine grain length and the standard fine grain length.
Further, in the seeding process, when the fusion is carried out, the crucible is turned to 4-7rpm, the crystal is turned to 7-10rpm, and the liquid level temperature of the silicon solution is 1447-1451 ℃.
Further, during necking, the crucible is switched to 4-7rpm, the crystal is switched to 7-10rpm, and the pulling speed is 5-7mm/min.
By adopting the technical scheme, in the crystal pulling process, before seeding, the length of dislocation-containing fine crystals is calculated, the length of the dislocation-containing fine crystals is the length of a section of fine crystals at the initial stage when seeding is started and exceeds the length of subsequent fine crystals of the dislocation-containing fine crystals, the dislocation is eliminated, and the dislocation is not existed.
Detailed Description
The present invention will be further described with reference to the following examples.
The embodiment of the invention relates to a method for improving a seeding process, which is used in a seeding process in a Czochralski single crystal process, and is particularly suitable for a single crystal growing on a 100-plane surface.
The preparation process of the czochralski single crystal comprises the working procedures of loading, melting, seeding, shouldering, shoulder turning, diameter equalizing, ending and the like, wherein in the seeding working procedure, the welding and necking are included, and fine crystals with a certain length are led out so as to eliminate crystal dislocation and ensure the quality of the pulled single crystal. After the polycrystalline silicon material in the quartz crucible is melted into the molten silicon in a solution state, seeding is carried out, when the seed crystal is inserted into the silicon solution, because the temperature difference between the seed crystal and the molten silicon is large, the high-temperature molten silicon can cause strong thermal shock to the seed crystal, the head of the seed crystal can generate a large amount of dislocation, when the fine crystal is led out after the fusion of the seed crystal and the molten silicon is completed, the dislocation can continuously extend along with the growth of the fine crystal and extends to the fine crystal, in order to eliminate the dislocation in the single crystal, the fine crystal with a certain length needs to be led out, the dislocation in the seed crystal is eliminated, so that the crystal obtained after the processes of shouldering, shoulder rotating, equal diameter, ending and the like after the seeding is the crystal without dislocation, and the quality of the single crystal is ensured.
A method for improving seeding process includes calculating standard length of dislocation-containing fine crystal before seeding, calculating actual fine crystal length according to standard length of fine crystal, seeding according to actual fine crystal length, knowing that fine crystal in standard length has dislocation during seeding process, and obtaining optimal seeding length after dislocation is eliminated by calculating standard length of dislocation-containing fine crystal when standard length is exceeded and seeding according to actual fine crystal length to reduce seeding time and obtain crystal without dislocation.
Specifically, when the standard length of the fine crystal grains containing dislocations is calculated as described above, the calculation is performed using the following formula:
L＝d*ctgα+A
wherein L is the standard length of the dislocation-containing fine crystals, d is the diameter of the fine crystals, alpha is the included angle between the dislocation line and the growth direction, and A is the correction length, and the standard length of the dislocation-containing fine crystals can be calculated according to the formula.
The angle between the dislocation line and the growth direction of the single crystal was 54 ° 44 'as described above, and the type of dislocation was the same for the single crystals of different specifications for the 100-plane grown single crystal, and the angle between the dislocation line and the growth direction of the single crystal was 54 ° 44'.
The correction length is 20-30mm, and the correction length is selected and set according to actual requirements, wherein no specific requirements are made; in this embodiment, preferably, a = m + n, m is the length of the transition stage between the seed crystal and the fine crystal, and n is the length of the transition stage between the fine crystal and the crystal, and the lengths of the transition stage between the seed crystal and the fine crystal and the transition stage between the fine crystal and the crystal are selected according to the type of the single crystal and the preset length during the seeding process, and are not specifically required here.
The diameter of the fine crystal is 4-6mm, and is selected according to the specification of the single crystal, and is not particularly required.
And calculating the actual fine crystal length according to the calculated standard fine crystal length and the preset fine crystal length in the seeding process, wherein the actual fine crystal length = the preset fine crystal length-the standard fine crystal length. The predetermined fine crystal length is selected according to the specifications of the single crystal and is not specifically required here.
In the seeding process, taking the actual fine crystal length as the seeding length to perform seeding; when welding is performed, the crucible rotation speed, the seed crystal rotation speed and the liquid level temperature of the silicon solution are controlled so that the welding can be performed smoothly. In the welding process, the crucible is switched to 4-7rpm, the crystal is switched to 7-10rpm, the liquid level temperature of the silicon solution is 1447-1451 ℃, and the selection is carried out according to actual requirements, wherein no specific requirement is made.
Necking after the fusion is finished, and controlling the crucible rotating speed, the seed crystal rotating speed and the pulling speed during necking so as to facilitate fine crystal pulling; in the necking process, the crucible is switched to 4-7rpm, the crystal is switched to 7-10rpm, the pulling speed is 5-7mm/min, and the crucible is selected according to actual requirements without specific requirements.
In this embodiment, because the theoretical value of the fine crystal length containing dislocation can be known through calculation, so, in the seeding process, the residence time of the seed crystal near the liquid level of the silicon solution can be reduced, the preheating time of the seed crystal is reduced, and then the thermal shock of the silicon melt to the seed crystal is reduced, so that the dislocation in the seed crystal is reduced.
Some specific examples are described below.
Example one
Before seeding, the standard length of the dislocation-containing fine crystals was calculated: l = d ctg alpha + A, wherein the diameter d of the fine crystal is 4mm, the included angle alpha between the dislocation line and the single crystal growth direction is 54 degrees 44', and the corrected length A is 20mm, so that the standard length L of the dislocation-containing fine crystal is calculated to be 22.84mm;
calculating the actual fine grain length: pulling a single crystal with the diameter of 295mm, wherein the preset fine crystal length is 300mm, the actual fine crystal length = the preset fine crystal length-the standard fine crystal length =277.16mm, so the actual fine crystal length is 277.16mm, of course, in order to facilitate the control of the seeding length in the seeding process, in order to shorten the fine crystal length as much as possible, and simultaneously, in the seed crystal, during welding, necking and during seeding, uninterrupted thermal shock, volatile matters, dust and the like are all eliminated as much as possible, and the actual fine crystal length can also be selected to be 250mm;
seeding, wherein during welding, the crucible is switched to 4rpm, the crystal is switched to 7rpm, and the liquid level temperature of the silicon solution is 1447 ℃;
after the welding is finished, necking, namely seeding fine grains, wherein the length of the fine grains is seeded according to the actual length of the fine grains which is obtained by calculation and is 250mm, the crucible is switched to 4rpm, the crystal is switched to 7rpm, and the pulling speed is 5mm/min;
and after the seeding is finished, the processes of shouldering, shoulder rotating, diameter equalizing, ending and the like are continuously carried out, and the crystal pulling conditions of the subsequent processes are tracked.
The pulled single crystal was compared to a single crystal pulled from a single crystal according to the prior art seeding process as shown in the following table:
as can be seen from the above table, when the seeding process of the present embodiment is used for seeding, the seeding length is shortened, the seeding time is shortened, and the primary crystallization rate, the bract breaking rate and the single crystal length have no deviation.
Example two
Before seeding, the standard length of the dislocation-containing fine crystals was calculated: l = d ctg alpha + A, wherein the diameter d of the fine crystal is 5mm, the included angle alpha between the dislocation line and the single crystal growth direction is 54 degrees 44', and the corrected length A is 25mm, then the standard length L of the dislocation-containing fine crystal is calculated to be 28.55mm;
calculating the actual fine grain length: pulling a single crystal with the diameter of 295mm, wherein the preset fine crystal length is 300mm, the actual fine crystal length = the preset fine crystal length-the standard fine crystal length =271.45mm, and therefore, the actual fine crystal length is 271.45mm, and certainly, in order to facilitate the control of the seeding length in the seeding process, in order to shorten the fine crystal length as much as possible, and simultaneously, in the seed crystal, during welding, necking and during seeding, uninterrupted thermal shock, volatile matters, dust and the like are all eliminated as much as possible, and the actual fine crystal length can also be selected to be 250mm;
seeding, wherein during welding, the crucible is changed to 5rpm, the crystal is changed to 8rpm, and the liquid level temperature of the silicon solution is 1448 ℃;
after the welding is finished, necking, namely seeding fine grains, wherein the length of the fine grains is seeded according to the actual length of the fine grains which is obtained by calculation and is 250mm, the crucible is turned to 5rpm, the crystal is turned to 8rpm, and the pulling speed is 6mm/min;
and after seeding is finished, the processes of shouldering, shoulder rotating, diameter equalizing, ending and the like are continuously carried out, and the crystal pulling condition of each subsequent process is tracked.
The pulled single crystal was compared to a single crystal pulled from a single crystal according to the prior art seeding process as shown in the following table:
from the above table, it can be seen that, when the seeding process of the present embodiment is used for seeding, the seeding length is shortened, the seeding time is shortened, and the primary crystallization rate, the bract breaking rate and the single crystal length have no deviation.
EXAMPLE III
Before seeding, the standard length of the dislocation-containing fine crystals was calculated: l = d ctg alpha + A, wherein the diameter d of the fine crystal is 6mm, the included angle alpha between the dislocation line and the growth direction of the single crystal is 54 degrees 44', and the corrected length A is 30mm, the standard length L of the dislocation-containing fine crystal is 34.26mm through calculation;
calculating the actual fine grain length: pulling a single crystal with the diameter of 295mm, wherein the preset fine grain length is 300mm, the actual fine grain length = the preset fine grain length-the standard fine grain length =265.74mm, and therefore, the actual fine grain length is 265.74mm, and certainly, in order to facilitate the control of the seeding length in the seeding process, and in order to shorten the fine grain length as much as possible, and simultaneously, in the seed crystal, during welding, necking and seeding, uninterrupted thermal shock, volatile matter, dust and the like are all eliminated as much as possible, and the actual fine grain length can also be selected to be 250mm;
seeding, wherein during welding, the crucible is changed to 6rpm, the crystal is changed to 9rpm, and the liquid level temperature of the silicon solution is 1449 ℃;
after the welding is finished, necking, namely seeding fine grains, wherein the length of the fine grains is seeded according to the actual length of the fine grains which is obtained by calculation and is 250mm, the crucible is converted into 6rpm, the crystal is converted into 9rpm, and the pulling speed is 7mm/min;
and after seeding is finished, the processes of shouldering, shoulder rotating, diameter equalizing, ending and the like are continuously carried out, and the crystal pulling condition of each subsequent process is tracked.
The pulled single crystal was compared to a single crystal pulled from a single crystal according to the prior art seeding process as shown in the following table:
from the above table, it can be seen that, when the seeding process of the present embodiment is used for seeding, the seeding length is shortened, the seeding time is shortened, and the primary crystallization rate, the bract breaking rate and the single crystal length have no deviation.
Example four
Before seeding, the standard length of the dislocation-containing fine crystals was calculated: l = d ctg alpha + A, wherein the diameter d of the fine crystal is 5mm, the included angle alpha between the dislocation line and the single crystal growth direction is 54 degrees 44', and the corrected length A is 30mm, so that the standard length L of the dislocation-containing fine crystal is 33.55mm;
calculating the actual fine grain length: pulling a single crystal with the diameter of 295mm, wherein the preset fine crystal length is 300mm, the actual fine crystal length = the preset fine crystal length-the standard fine crystal length =266.45mm, so the actual fine crystal length is 266.45mm, of course, in order to facilitate the control of the seeding length in the seeding process, in order to shorten the fine crystal length as much as possible, and simultaneously, in the seed crystal, during welding, necking and during seeding, uninterrupted thermal shock, volatile matters, dust and the like are all eliminated as much as possible, and the actual fine crystal length can also be selected to be 250mm;
seeding, wherein during welding, the crucible is switched to 7rpm, the crystal is switched to 10rpm, and the liquid level temperature of the silicon solution is 1450 ℃;
after the welding is finished, necking, namely seeding fine grains, wherein the length of the fine grains is seeded according to the actual length of the fine grains which is obtained by calculation and is 250mm, the crucible is switched to 7rpm, the crystal is switched to 10rpm, and the pulling speed is 6.5mm/min;
and after seeding is finished, the processes of shouldering, shoulder rotating, diameter equalizing, ending and the like are continuously carried out, and the crystal pulling condition of each subsequent process is tracked.
The pulled single crystal was compared to a single crystal pulled from a single crystal according to the prior art seeding process as shown in the following table:
from the above table, it can be seen that, when the seeding process of the present embodiment is used for seeding, the seeding length is shortened, the seeding time is shortened, and the primary crystallization rate, the bract breaking rate and the single crystal length have no deviation.
It can be understood from the above embodiments that the diameter of the fine crystal is selected according to the type of the single crystal to be pulled, the length of the fine crystal containing dislocations is calculated based on the angle between the dislocation line and the growth direction and the diameter of the fine crystal, and the actual length of the fine crystal in the actual crystal pulling process is calculated based on the preset length of the fine crystal of the single crystal to be pulled, and the fine crystal of the actual length of the fine crystal is the dislocation-eliminated fine crystal having no dislocations, so as to ensure the quality of the single crystal obtained after the subsequent crystal pulling process is completed.
By adopting the technical scheme, in the crystal pulling process, before seeding, the dislocation-containing fine crystal length is calculated, the dislocation-containing fine crystal length is the length of a section of fine crystal at the initial stage when seeding is started and exceeds the length of subsequent fine crystal of the dislocation-containing fine crystal length, dislocation is eliminated, and dislocation is not existed.
The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.
Claims (9)
1. A method for improving a seeding process is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
calculating a standard length of fine crystals containing dislocations before seeding;
calculating actual fine grain length according to the standard length of fine grains;
seeding: and seeding according to the actual fine grain length.
2. The method for improving seeding process according to claim 1, wherein: when calculating the standard length of the fine crystal containing dislocations, the following formula is used for calculation:
L＝d*ctgα+A
wherein L is the length of the dislocation-containing fine crystal, d is the diameter of the fine crystal, alpha is the included angle between the dislocation line and the growth direction, and A is the correction length.
3. The method for improving seeding process according to claim 2, wherein: the dislocation line forms an angle of 54 degrees 44' with the direction of single crystal growth.
4. The method for improving seeding process according to claim 3, wherein: the correction length is 20-30mm.
5. The method for improving seeding process according to claim 2, wherein: the correction length A = m + n, wherein m is the transition stage length of the seed crystal and the fine crystal, and n is the transition stage length of the fine crystal and the crystal.
6. The method for improving a seeding process according to any one of claims 2 to 5, wherein: the diameter of the fine crystals is 4-6mm.
7. The method for improving seeding process according to any one of claims 1 to 5, wherein: the actual fine grain length is the difference between the preset fine grain length and the standard fine grain length.
8. The method for improving seeding process according to any one of claims 1 to 5, wherein: in the seeding process, when the fusion is carried out, the crucible is turned to 4-7rpm, the crystal is turned to 7-10rpm, and the liquid level temperature of the silicon solution is 1447-1451 ℃.
9. The method for improving seeding process according to claim 8, wherein: during necking, the crucible is switched to 4-7rpm, the crystal is switched to 7-10rpm, and the pulling speed is 5-7mm/min.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116219535A (en) * | 2023-05-08 | 2023-06-06 | 苏州晨晖智能设备有限公司 | Crystal growth method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116219535A (en) * | 2023-05-08 | 2023-06-06 | 苏州晨晖智能设备有限公司 | Crystal growth method |
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