Temperature adjusting method capable of increasing survival rate of automatic seeding

Abstract

The invention discloses a temperature adjusting method capable of increasing the survival rate of automatic seeding, which comprises the following steps: firstly, measuring the temperature of a crystal bud grown from an original seed crystal for the first time, and roughly adjusting the power of a heater so that the crystal bud is stably maintained for 180s; the number of crystal bracts is four and stable through fine adjustment, the variation of original seed crystals is smaller than or equal to 0.2 mm, the fluctuation of the temperature of the liquid level in a crucible is smaller than or equal to 0.5 DEG C, the time lasts for 300 s or above, the fluctuation of the power of a heater is smaller than or equal to 0.2 kw, and the power of the heater at the moment serves as the seeding power; and then, when the residual quantity in the crucible is small and the heat loss is fast, the PID temperature control system regulates and controls the heater. The problem of manual seeding is solved through the temperature regulation and control, the automatic temperature regulation standard of the system is consistent, the seeding survival rate result is stable, the seeding power is continuously self-learned and adjusted through the system, the seeding power of the next time is automatically given, and the power does not need to be manually given or adjusted, so that the whole-process one-key crystal pulling from feeding to section taking is realized, and the production efficiency is improved. And no human intervention is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of single crystal silicon production, and in particular, relates to a temperature control method capable of improving the survival rate of automatic seeding. Background Art

[0002] In the Czochralski method of single crystal silicon production, the fully automatic processes that have been realized include chemical synthesis, welding, seeding, shoulder release, shoulder rotation, equal diameter, finishing, segment feeding, and furnace shutdown. The process from welding to temperature adjustment to seeding is still mainly operated by humans. Due to the limitations of various factors such as cameras, furnace structure, and thermal field structure, the automatic identification of the number and time of crystal buds is not accurate enough, resulting in the inability to achieve automatic temperature adjustment to seeding. Even though some companies have achieved automatic seeding, the survival rate is not high, at around 70%, and visual observation by centralized control personnel and manual seeding are still required. The process operation has high requirements on the skill level of personnel, and different people have different operating methods. Therefore, the survival rate is always difficult to stabilize at a high level. Summary of the invention

[0003] In order to overcome the problems existing in the prior art, the present invention proposes a temperature control method that can improve the survival rate of automatic crystal seeding. The method of the present invention can improve crystal pulling automation, improve the survival rate of crystal seeding, and reduce the requirements on the skill level of operators, thereby increasing the staff viewing rate and reducing production and operation costs.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions: A temperature adjustment method for improving the survival rate of automatic seeding comprises the following steps: S1, when the CCD camera system recognizes that the original seed crystal grows a bud for the first time, and records the liquid surface temperature at this time as T1; S2, PID temperature control system controls the heater to perform rough adjustment according to the liquid surface temperature T1. The rough adjustment method is: If T1=1447℃, the heater power is increased by 1kw; If T1=1448℃, the heater power is increased by 0.5kw; If T1=1449℃, the heater power is increased by 0.2kw; If T1=1450℃, the heater power is not adjusted; If T1=1451℃, the heater power is reduced by 0.2kw; If T1=1452℃, the heater power is reduced by 0.5kw; If T1=1453℃, the heater power is reduced by 1kw; S3, if the crystal bud is stable for more than 180 seconds, record the liquid surface temperature T2 at this time; S4, PID temperature control system controls the heater to perform fine adjustment according to the liquid surface temperature T2. The fine adjustment method is: If T1=1449℃, the heater power is increased by 0.2kw; If T1=1449.5℃, the heater power is increased by 0.1kw; If T1=1450℃, the heater power is not adjusted; If T1=1450.5℃, the heater power is reduced by 0.1kw; If T1=1451℃, the heater power is reduced by 0.2kw; S5, if the following conditions are met at the same time, the seeding temperature adjustment is completed, the PLC control system records the temperature at this time as the seeding power, and starts seeding; the conditions are: ①. The change in the original seed crystal diameter is ≤0.2mm; ② The four crystal buds are stable for more than 180 seconds, and there is no disappearance or enlargement of crystals in the middle; ③ The temperature fluctuation of the liquid surface in the crucible is ≤0.5℃, lasting for more than 300s, and the fluctuation is up and down, not rising or falling all the time; ④. Heater power fluctuation ≤ 0.2kw; S6, during the crystal pulling process, if no more feeding production is carried out and there is less residual material in the crucible, the PID temperature control system controls the liquid surface temperature according to the residual material amount in the quartz crucible, and realizes rapid temperature adjustment by giving a certain power compensation coefficient until the seeding conditions are met; the control method is: actual power adjustment value = coarse power change or fine power change × power compensation coefficient, where: Coarse adjustment power change = power when liquid surface temperature is T1 - power when temperature is T2; The change in fine-tuning power = the power when the liquid surface temperature is T2 - the power when seeding begins; The method for determining whether to use coarse adjustment or fine adjustment of power change is: When the temperature changes within 1450±3℃, the coarse adjustment power change × power compensation coefficient is used for adjustment; When the temperature changes within 1450±1℃, the power change amount × power compensation coefficient is used for fine-tuning adjustment; The power compensation coefficient is determined as follows: When the remaining material is 550kg, the power compensation coefficient is 0.2; When the remaining material is 450kg, the power compensation coefficient is 0.5; When the remaining material is 350kg, the power compensation coefficient is 1; When the remaining material is 250kg, the power compensation coefficient is 1.5; When the remaining material is 150kg, the power compensation coefficient is 2.

[0005] Furthermore, the pixel value of the CCD camera system is greater than 12 million pixels.

[0006] Furthermore, the argon flow rate in the single crystal furnace is controlled between 80-120slpm, and the furnace pressure is controlled between 5-10torr.

[0007] Furthermore, when the PID temperature control system controls the temperature adjustment of the heater, the solid-liquid interface needs to remain without obvious fluctuations, and the diameter deviation within 3s of diameter measurement is less than 0.5mm.

[0008] Through the above technical solution, the present invention can at least achieve the following beneficial effects: The temperature control method proposed in this patent can realize the system's automatic transition from temperature control to crystal seeding, solving a major problem of manual crystal seeding. The system's automatic temperature control standards are consistent, and the seeding survival rate results are stable. The system continuously self-learns to adjust the seeding power and automatically gives the next seeding power without manual power setting or adjustment, thereby achieving one-click crystal pulling from adding materials to taking sections without human intervention. In addition, our company has verified in actual production that in 33-inch to 36-inch quartz crucibles, the seeding survival rate has increased from 75% to 95%, and production efficiency has increased by 8%. DETAILED DESCRIPTION

[0009] Unless otherwise specified, the materials and reagents used in the present invention are commercially available.

[0010] Embodiment, a temperature adjustment method capable of improving the survival rate of automatic seeding comprises the following steps: S1, when the CCD camera system recognizes that the original seed crystal grows a bud for the first time, and records the liquid surface temperature at this time as T1; S2, PID temperature control system controls the heater to perform rough adjustment according to the liquid surface temperature T1. The rough adjustment method is: If T1=1447℃, the heater power is increased by 1kw; If T1=1448℃, the heater power is increased by 0.5kw; If T1=1449℃, the heater power is increased by 0.2kw; If T1=1450℃, the heater power is not adjusted; If T1=1451℃, the heater power is reduced by 0.2kw; If T1=1452℃, the heater power is reduced by 0.5kw; If T1=1453℃, the heater power is reduced by 1kw; S3, if the crystal bud is stable for more than 180 seconds, record the liquid surface temperature T2 at this time; S4, PID temperature control system controls the heater to perform fine adjustment according to the liquid surface temperature T2. The fine adjustment method is: If T1=1449℃, the heater power is increased by 0.2kw; If T1=1449.5℃, the heater power is increased by 0.1kw; If T1=1450℃, the heater power is not adjusted; If T1=1450.5℃, the heater power is reduced by 0.1kw; If T1=1451℃, the heater power is reduced by 0.2kw; S5, if the following conditions are met at the same time, the seeding temperature adjustment is completed, the PLC control system records the temperature at this time as the seeding power, and starts seeding; the conditions are: ①. The change in the original seed crystal diameter is ≤0.2mm; ② The four crystal buds are stable for more than 180 seconds, and there is no disappearance or enlargement of crystals in the middle; ③ The temperature fluctuation of the liquid surface in the crucible is ≤0.5℃, lasting for more than 300s, and the fluctuation is up and down, not rising or falling all the time; ④. Heater power fluctuation ≤ 0.2kw; S6, during the crystal pulling process, if no more feeding production is carried out and there is less residual material in the crucible, the PID temperature control system controls the liquid surface temperature according to the residual material amount in the quartz crucible, and realizes rapid temperature adjustment by giving a certain power compensation coefficient until the seeding conditions are met; the control method is: Actual power adjustment value = coarse power change or fine power change × power compensation coefficient, where: Coarse adjustment power change = power when liquid surface temperature is T1 - power when temperature is T2; The change in fine-tuning power = the power when the liquid surface temperature is T2 - the power when seeding begins; The method for determining whether to use coarse adjustment or fine adjustment of power change is: When the temperature changes within 1450±3℃, the coarse adjustment power change × power compensation coefficient is used for adjustment; When the temperature changes within 1450±1℃, the power change amount × power compensation coefficient is used for fine-tuning adjustment; The power compensation coefficient is determined as follows: When the remaining material is 550kg, the power compensation coefficient is 0.2; When the remaining material is 450kg, the power compensation coefficient is 0.5; When the remaining material is 350kg, the power compensation coefficient is 1; When the remaining material is 250kg, the power compensation coefficient is 1.5; When the remaining material is 150kg, the power compensation coefficient is 2.

[0011] In one embodiment, the pixel value of the CCD camera system is more than 12 million pixels. A CCD camera with a higher pixel value can achieve better recognition effect.

[0012] In one embodiment, the argon flow rate in the single crystal furnace is controlled between 80-120 slpm, and the furnace pressure is controlled between 5-10 torr. A relatively stable pressure in the furnace can ensure the stability of the identification and detection results.

[0013] In one embodiment, when the PID temperature control system controls the temperature adjustment of the heater, the solid-liquid interface needs to remain without obvious fluctuations, and the diameter deviation within 3s of the diameter measurement is less than 0.5mm. The solid-liquid interface needs to remain without obvious fluctuations, and the diameter deviation within 3s of the diameter measurement is less than 0.5mm, which can further ensure the accuracy of the identification measurement results.

[0014] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A temperature control method for improving the survival rate of automatic seeding, characterized in that: The following steps are included: S1, when the CCD camera system recognizes that the original seed crystal grows a bud for the first time, and records the liquid surface temperature at this time as T1; S2, PID temperature control system controls the heater to perform rough adjustment according to the liquid surface temperature T1. The rough adjustment method is: If T1=1447℃, the heater power is increased by 1kw; If T1=1448℃, the heater power is increased by 0.5kw; If T1=1449℃, the heater power is increased by 0.2kw; If T1=1450℃, the heater power is not adjusted; If T1=1451℃, the heater power is reduced by 0.2kw; If T1=1452℃, the heater power is reduced by 0.5kw; If T1=1453℃, the heater power is reduced by 1kw; S3, if the crystal bud is stable for more than 180 seconds, record the liquid surface temperature T2 at this time; S4, PID temperature control system controls the heater to perform fine adjustment according to the liquid surface temperature T2. The fine adjustment method is: If T1=1449℃, the heater power is increased by 0.2kw; If T1=1449.5℃, the heater power is increased by 0.1kw; If T1=1450℃, the heater power is not adjusted; If T1=1450.5℃, the heater power is reduced by 0.1kw; If T1=1451℃, the heater power is reduced by 0.2kw; S5, if the following conditions are met at the same time, the seeding temperature adjustment is completed, the PLC control system records the temperature at this time as the seeding power, and starts seeding; the conditions are: ①. The change in the original seed crystal diameter is ≤0.2mm; ② The four crystal buds are stable for more than 180 seconds, and there is no disappearance or enlargement of crystals in the middle; ③ The temperature fluctuation of the liquid surface in the crucible is ≤0.5℃, lasting for more than 300s, and the fluctuation is up and down, not rising or falling all the time; ④. Heater power fluctuation ≤ 0.2kw; S6, during the crystal pulling process, if no more feeding production is carried out and there is less residual material in the crucible, the PID temperature control system controls the liquid surface temperature according to the residual material amount in the quartz crucible, and realizes rapid temperature adjustment by giving a certain power compensation coefficient until the seeding conditions are met; The control method is: Actual power adjustment value = coarse power change or fine power change × power compensation coefficient, where: Coarse adjustment power change = power when liquid surface temperature is T1 - power when temperature is T2; The change in fine-tuning power = the power when the liquid surface temperature is T2 - the power when seeding begins; The method for determining whether to use coarse adjustment or fine adjustment of power change is: When the temperature changes within 1450±3℃, the coarse adjustment power change × power compensation coefficient is used for adjustment; When the temperature changes within 1450±1℃, the power change amount × power compensation coefficient is used for fine-tuning adjustment; The power compensation coefficient is determined as follows: When the remaining material is 550kg, the power compensation coefficient is 0.2; When the remaining material is 450kg, the power compensation coefficient is 0.5; When the remaining material is 350kg, the power compensation coefficient is 1; When the remaining material is 250kg, the power compensation coefficient is 1.5; When the remaining material is 150kg, the power compensation coefficient is 2.

2. A temperature control method for improving the survival rate of automatic seeding according to claim 1, characterized in that: The pixel value of the CCD camera system is more than 12 million pixels.

3. A temperature control method for improving the survival rate of automatic seeding according to claim 1, characterized in that: The argon flow rate in the single crystal furnace is controlled between 80-120slpm, and the furnace pressure is controlled between 5-10torr.

4. A temperature control method for improving the survival rate of automatic seeding according to claim 1, characterized in that: When the PID temperature control system controls the temperature of the heater, the solid-liquid interface must remain without obvious fluctuations, and the diameter deviation within 3 seconds of diameter measurement is less than 0.5 mm.