Growth control method for equal-diameter process of czochralski single crystal

Abstract

The invention provides a growth control method for a straight pulling single crystal equal-diameter process. The growth control method comprises the following steps: acquiring an actual pulling speed after a single crystal is subjected to equal-diameter growth for a set length; when the deviation value between the actual pulling speed and the set pulling speed is larger than the set deviation value, the heating power is adjusted so that the actual pulling speed can be matched with the adjusted pulling speed, and the adjusted pulling speed is set between the actual pulling speed and the set pulling speed; and when the deviation value of the actual pulling speed and the set pulling speed is smaller than or equal to the set deviation value, the heating power is adjusted so that the actual pulling speed can be matched with the set pulling speed. The method has the beneficial effects that the actual pulling speed is gradually and slowly adjusted according to a constant deviation value and is gradually matched with the set pulling speed in the straight pulling single crystal equal-diameter process, so that the fluctuation amplitude of the pulling speed is reduced, and the problem of single crystal bud breakage caused by overshoot temperature adjustment is effectively avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of Czochralski single crystals, and in particular relates to a growth control method for a Czochralski single crystal isodiameter process. Background Art

[0002] When pulling single crystals by the Czochralski method, during the equal-diameter process, due to the differences in furnaces and the different residual materials in the furnace, the equal-diameter curves of different furnaces at different operating stages are quite different. There may be a certain deviation between the set pulling speed and the actual pulling speed during the process. If no adjustment is made, it will be detrimental to the improvement and stability of the pulling speed in the later stage, and the proportion of broken buds will also increase. In the prior art, after the length of the single crystal equal-diameter growth interval is reached, the growth control module intervenes, and adjusts the heating power through PID calculation according to the deviation between the actual pulling speed and the set pulling speed, so that the actual pulling speed directly matches the set pulling speed. However, if the actual pulling speed deviates greatly from the set pulling speed, the actual pulling speed is directly matched with the set pulling speed, and the pulling speed fluctuates greatly, which can easily cause temperature regulation overshoot and lead to single crystal broken buds. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a growth control method for the equal-diameter process of vertical pulling single crystals, which effectively solves the problem that in the equal-diameter process of vertical pulling single crystals, the actual pulling speed directly matches the set pulling speed, the temperature adjustment is overshot, and the single crystal bud breaks, thereby overcoming the shortcomings of the prior art.

[0004] The technical solution adopted by the present invention is: a growth control method for a Czochralski single crystal equal diameter process, comprising the following steps:

[0005] Obtain the actual pulling speed of single crystal equal diameter growth;

[0006] When the deviation between the actual pulling speed and the set pulling speed is greater than the set deviation, the heating power is adjusted to make the actual pulling speed match the adjusted pulling speed, and the adjusted pulling speed is set between the actual pulling speed and the set pulling speed;

[0007] When the deviation value between the actual pulling speed and the set pulling speed is less than or equal to the set deviation value, the heating power is adjusted to make the actual pulling speed match the set pulling speed.

[0008] Optionally, the deviation value between the adjusted pulling speed and the actual pulling speed is a fixed value.

[0009] Optionally, the fixed value is equal to the set deviation value.

[0010] Optionally, in the step of obtaining the actual pulling speed of the single crystal isodiametric growth, the actual pulling speed is obtained after the single crystal isodiametrically grown for a set length, and the set length is 300-600 mm.

[0011] Optionally, the set deviation value is 3-10mm / h.

[0012] Optionally, when adjusting the heating power,

[0013] When the deviation between the actual pulling speed and the set pulling speed is greater than the set deviation, the adjustment range of the heating power per hour = the set deviation × the set coefficient;

[0014] When the deviation between the actual pulling speed and the set pulling speed is less than or equal to the set deviation, the adjustment range of the heating power per hour=the deviation between the actual pulling speed and the set pulling speed×the set coefficient.

[0015] Optionally, the setting coefficient is 0-3.

[0016] Optionally, the set length is set to 320m, 350mm, 400mm, 450mm, 500mm, 550mm or 580mm.

[0017] Optionally, the set deviation value is set to 3.5mm / h, 4mm / h, 5mm / h, 6mm / h, 7mm / h, 8mm / h, 9mm / h or 9.5mm / h.

[0018] Optionally, the setting coefficient is set to 0.4, 0.5, 0.8, 1, 1.3, 1.5, 1.8, 2, 2.3, 2.5 or 2.8.

[0019] The advantages and positive effects of the present invention are as follows: due to the adoption of the above technical scheme, during the process of pulling single crystals to equal diameters, the actual pulling speed is gradually adjusted slowly with a constant deviation value and gradually matched with the set pulling speed, thereby reducing the fluctuation amplitude of the pulling speed and effectively avoiding the problem of single crystal breakage caused by temperature adjustment overshoot. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of a growth control method for a Czochralski single crystal equal-diameter process according to an embodiment of the present invention.

[0021] Figure 2 It is a growth control curve diagram of a growth control method for a Czochralski single crystal equal diameter process according to an embodiment of the present invention.

[0022] Figure 3 It is a growth control curve diagram of a growth control method for a Czochralski single crystal equal diameter process according to an embodiment of the present invention.

[0023] In the figure:

[0024] a. Actual pulling speed curve b. Adjusted pulling speed curve c. Set pulling speed curve DETAILED DESCRIPTION

[0025] An embodiment of the present invention provides a growth control method for a Czochralski single crystal equal diameter process, and the embodiment of the present invention is described below with reference to the accompanying drawings.

[0026] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "set" and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0027] like Figure 1 As shown, a growth control method for a Czochralski single crystal isodiameter process according to an embodiment of the present invention comprises the following steps:

[0028] Obtaining the actual pulling speed of the single crystal isodiameter growth. In order to be able to adjust the actual pulling speed in real time, optionally, the actual pulling speed is obtained in real time during the process of obtaining the actual pulling speed.

[0029] Calculate the deviation between the actual drawing speed and the set drawing speed. The set drawing speed is the drawing speed set by the process parameters.

[0030] When the deviation between the actual pulling speed and the set pulling speed is greater than the set deviation value, the heating power is adjusted to automatically match the actual pulling speed with the adjusted pulling speed, and the adjusted pulling speed is a self-set pulling speed between the actual pulling speed and the set pulling speed. When the deviation between the actual pulling speed and the set pulling speed is too large and greater than the set deviation value, directly matching the actual pulling speed with the set pulling speed can easily lead to overshoot of temperature regulation, that is, the temperature adjustment amplitude is too large, resulting in excessive fluctuation of pulling speed, causing single crystal breakage. At this time, setting an adjusted pulling speed between the actual pulling speed and the set pulling speed can make the temperature adjustment and the fluctuation of pulling speed more moderate, thereby ensuring the quality of crystal pulling.

[0031] When the deviation between the actual pulling speed and the set pulling speed is less than or equal to the set deviation value, the heating power is adjusted to automatically match the actual pulling speed with the set pulling speed.

[0032] Optionally, the deviation between the adjusted pulling speed and the actual pulling speed is a fixed value. In the actual regulation process, the actual pulling speed changes in real time, and the adjusted pulling speed also changes accordingly. In order to ensure the continuity and stability of the regulation, the deviation between the adjusted pulling speed and the actual pulling speed is a fixed value.

[0033] Optionally, the fixed value is equal to the set deviation value, and the set deviation value is an empirical value.

[0034] Optionally, the set deviation value is set to 3-10 mm / h. The set deviation value can be set to 3.5 mm / h, 4 mm / h, 5 mm / h, 6 mm / h, 7 mm / h, 8 mm / h, 9 mm / h or 9.5 mm / h, etc.

[0035] Optionally, the actual pulling speed is obtained after the single crystal is grown to a set length, and the set length is 300-600mm. In the early stage of the single crystal equal diameter process, the crystal pulling is unstable and the bud is prone to breakage. Therefore, the pulling speed is adjusted after the single crystal is grown to a set length. The set length can be set to 320m, 350mm, 400mm, 450mm, 500mm, 550mm or 580mm, etc.

[0036] Optionally, the adjustment range of the heating power is automatically calculated by PID, and the temperature of the thermal field is controlled by adjusting the heating power of the thermal field, thereby adjusting the pulling speed of the single crystal. When the deviation between the actual pulling speed and the set pulling speed is greater than the set deviation value, the adjustment range of the heating power per hour = the set deviation value × the set coefficient; when the deviation between the actual pulling speed and the set pulling speed is less than or equal to the set deviation value, the adjustment range of the heating power per hour = the deviation between the actual pulling speed and the set pulling speed × the set coefficient. The heating power is linearly adjusted.

[0037] Optionally, the setting coefficient is set to 0-3. The setting coefficient can be set to 0.4, 0.5, 0.8, 1, 1.3, 1.5, 1.8, 2, 2.3, 2.5 or 2.8, etc.

[0038] Embodiment 1: Figure 2 As shown, a growth control method for a CZ single crystal isodiameter process is used to obtain the actual pulling speed V of the single crystal after the single crystal isodiameter grows to 300 mm. 实1 =89mm / h, the set pulling speed at this time is V 设1 =95mm / h, the deviation value V between the actual pulling speed and the set pulling speed 偏1 =6mm / h, set the deviation value to 3mm / h, V 偏1 Greater than the set deviation value. At this time, set the adjustment speed V 调1 =92mm / h, adjust the pulling speed V 调1 The actual pulling speed V 实1The deviation value is the set deviation value and remains unchanged. Through PID calculation, the heating power is adjusted to automatically match the actual pulling speed with the adjusted pulling speed. At this time, the heating power is 60kW, and the actual pulling speed is lower than the set pulling speed. Therefore, it is necessary to increase the pulling speed and reduce the temperature of the thermal field, that is, reduce the heating power. The adjustment range of power = set deviation value × setting coefficient. In this embodiment, the setting coefficient is 0.3. The adjustment range of power per hour is 0.9kW, that is, the heating power is linearly reduced by a decrease of 0.9KW / h.

[0039] When the actual pulling speed V of the single crystal is obtained 实2 =92mm / h, the set pulling speed at this time is V 设2 =95mm / h, the deviation value V between the actual pulling speed and the set pulling speed 偏2 =3mm / h, V 偏2 Equal to the set deviation value. At this time, the adjusted pulling speed is the set pulling speed. Through PID calculation, the heating power is adjusted to automatically match the actual pulling speed with the set pulling speed. At this time, the heating power is 59.1kW, and the actual pulling speed is lower than the set pulling speed. Therefore, it is necessary to increase the pulling speed and reduce the temperature of the thermal field, that is, reduce the heating power. The power adjustment range per hour is 0.9kW, that is, the heating power is linearly reduced by a decrease of 0.9KW / h.

[0040] When the actual pulling speed V of the single crystal is obtained 实3 =93mm / h, the set pulling speed at this time is V 设3 =95mm / h, the deviation value V between the actual pulling speed and the set pulling speed 偏3 =2mm / h, V 偏3 Less than the set deviation value. At this time, the adjusted pulling speed is the set pulling speed. Through PID calculation, the heating power is adjusted to automatically match the actual pulling speed with the set pulling speed. At this time, the heating power is 58.2kW, and the actual pulling speed is lower than the set pulling speed. Therefore, it is necessary to increase the pulling speed and reduce the temperature of the thermal field, that is, reduce the heating power. The power adjustment range per hour is 0.6kW, that is, the heating power is linearly reduced by a decrease of 0.6KW / h.

[0041] Embodiment 2: Figure 3 As shown, a growth control method for a CZ-pulled single crystal isodiameter process is used to obtain the actual pulling speed V of the single crystal after the single crystal isodiameter grows to 600 mm. 实1 =108mm / h, the set pulling speed at this time is V 设1 =95mm / h, the deviation value V between the actual pulling speed and the set pulling speed 偏1 =13mm / h, set the deviation value to 10mm / h, V 偏1 Greater than the set deviation value. At this time, set the adjustment speed V 调1 =98mm / h, adjust the pulling speed V 调1 The actual pulling speed V实1 The deviation value is the set deviation value and remains unchanged. Through PID calculation, the heating power is adjusted to automatically match the actual pulling speed with the adjusted pulling speed. At this time, the heating power is 60kW, and the actual pulling speed is higher than the set pulling speed. Therefore, it is necessary to reduce the pulling speed and increase the temperature of the thermal field, that is, to increase the heating power. The adjustment range of power = set deviation value × set coefficient. In this embodiment, the set coefficient is 2. The adjustment range of power per hour is 20kW, that is, the heating power is linearly increased by an increase of 20KW / h.

[0042] When the actual pulling speed V of the single crystal is obtained 实2 =105mm / h, the set pulling speed at this time is V 设2 =95mm / h, the deviation value V between the actual pulling speed and the set pulling speed 偏2 =10mm / h, V 偏2 Equal to the set deviation value. At this time, the adjusted pulling speed is the set pulling speed. Through PID calculation, the heating power is adjusted to automatically match the actual pulling speed with the set pulling speed. At this time, the heating power is 80kW, and the actual pulling speed is higher than the set pulling speed. Therefore, it is necessary to reduce the pulling speed and increase the temperature of the thermal field, that is, to increase the heating power. The power adjustment range per hour is 20kW, that is, the heating power is linearly increased by 20KW / h.

[0043] When the actual pulling speed V of the single crystal is obtained 实3 =100mm / h, the set pulling speed at this time is V 设3 =95mm / h, the deviation value V between the actual pulling speed and the set pulling speed 偏3 =5mm / h, V 偏2 Less than the set deviation value. At this time, the adjusted pulling speed is the set pulling speed. Through PID calculation, the heating power is adjusted to automatically match the actual pulling speed with the set pulling speed. At this time, the heating power is 100kW, and the actual pulling speed is higher than the set pulling speed. Therefore, it is necessary to reduce the pulling speed and increase the temperature of the thermal field, that is, to increase the heating power. The power adjustment range per hour is 10kW, that is, the heating power is linearly increased by an increase of 10KW / h.

[0044] The advantages and positive effects of the present invention are:

[0045] In the process of pulling single crystals to equal diameter, the actual pulling speed is gradually adjusted with a constant deviation value to gradually match the set pulling speed, which reduces the fluctuation range of the pulling speed and effectively avoids the problem of single crystal breakage caused by temperature adjustment overshoot.

[0046] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for controlling the growth of a CZ-type single crystal during a uniform diameter process, characterized in that: The following steps are involved: Obtain the actual pulling speed of single crystal equal diameter growth; When the deviation between the actual pulling speed and the set pulling speed is greater than the set deviation, the heating power is adjusted to make the actual pulling speed match the adjusted pulling speed, and the adjusted pulling speed is set between the actual pulling speed and the set pulling speed; When the deviation value between the actual pulling speed and the set pulling speed is less than or equal to the set deviation value, the heating power is adjusted to make the actual pulling speed match the set pulling speed.

2. The method for controlling the growth of a Czochralski single crystal during a uniform diameter process according to claim 1, characterized in that: The deviation value between the adjusted pulling speed and the actual pulling speed is a fixed value.

3. The method for controlling the growth of a Czochralski single crystal in a uniform diameter process according to claim 2, characterized in that: The fixed value is equal to the set deviation value.

4. The method for controlling the growth of a Czochralski single crystal in a constant diameter process according to any one of claims 1 to 3, characterized in that: In the step of obtaining the actual pulling speed of the single crystal isodiametric growth, the actual pulling speed is obtained after the single crystal isodiametrically grown for a set length, and the set length is 300-600 mm.

5. The method for controlling the growth of a Czochralski single crystal in a uniform diameter process according to claim 4, characterized in that: The set deviation value is 3-10mm / h.

6. The method for controlling the growth of a Czochralski single crystal in a constant diameter process according to any one of claims 1 to 3 and 5, characterized in that: When adjusting the heating power, When the deviation between the actual pulling speed and the set pulling speed is greater than the set deviation, the adjustment range of the heating power per hour = the set deviation × the set coefficient; When the deviation between the actual pulling speed and the set pulling speed is less than or equal to the set deviation, the adjustment range of the heating power per hour=the deviation between the actual pulling speed and the set pulling speed×the set coefficient.

7. The method for controlling the growth of a Czochralski single crystal in a uniform diameter process according to claim 6, characterized in that: The setting coefficient is 0-3.

8. The method for controlling the growth of a Czochralski single crystal in a uniform diameter process according to claim 4, characterized in that: The set length is set to 320m, 350mm, 400mm, 450mm, 500mm, 550mm or 580mm.

9. The method for controlling the growth of a Czochralski single crystal in a uniform diameter process according to claim 5, characterized in that: The set deviation value is set to 3.5mm / h, 4mm / h, 5mm / h, 6mm / h, 7mm / h, 8mm / h, 9mm / h or 9.5mm / h.

10. The method for controlling the growth of a Czochralski single crystal in a uniform diameter process according to claim 7, characterized in that: The setting coefficient is set to 0.4, 0.5, 0.8, 1, 1.3, 1.5, 1.8, 2, 2.3, 2.5 or 2.8.

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