Method for controlling czochralski liquid level distance

Abstract

A method for controlling a Czochralski liquid level distance. The method comprises: when entering a temperature stabilization procedure, measuring the temperature of the surface of a silicon melt in a crucible, and acquiring temperature data T of the surface of the silicon melt; acquiring a first difference value ΔT by means of the temperature data T and preset temperature data T0, and when the first difference value ΔT ranges from 10 ℃ to 50 ℃, acquiring position data S of a guide tube; acquiring a second difference value ΔS by means of the position data S and preset position data S0; and on the basis of the first difference value ΔT and the second difference value ΔS, adjusting the position of the crucible.

Description

A method for controlling the liquid level distance of a CZ single crystal

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 21, 2023, with application number 202311234193.2 and invention name “A method for controlling the liquid level distance of a vertically pulled single crystal”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of single crystal growth, and in particular to a method for controlling the liquid level distance of a Czochralski single crystal. Background Art

[0003] Controlling the liquid level distance in the Czochralski method, especially identifying the initial liquid level distance during crystal growth or monitoring the liquid level distance during crystal growth, is crucial for crystal formation and product parameters. Technical issues

[0004] Inconsistencies between the liquid level and process requirements during the Czochralski method can lead to temperature gradient variations, altering the V / G ratio, and inducing OISF COP defects and even bud breakage. Furthermore, inconsistencies between the liquid level and process requirements can lead to temperature variations in the thermal field, causing deviations in quality parameters such as RRV (cross-sectional uniformity) and ORG (oxygen radial gradient). Technical Solutions

[0005] The present invention provides a method for controlling the liquid level distance of a Czochralski single crystal, comprising:

[0006] When entering the temperature stabilization process, the temperature of the silicon melt surface in the crucible is measured to obtain the temperature data T of the silicon melt surface;

[0007] Obtaining a first difference ΔT from the temperature data T and the preset temperature data T0, and obtaining position data S of the guide tube when the first difference ΔT is in the range of 10° C. to 50° C.;

[0008] Obtaining a second difference ΔS through the position data S and the preset position data S0;

[0009] Based on the first difference ΔT and the second difference ΔS, the position of the crucible is adjusted.

[0010] In some embodiments, the temperature data T ranges from 1400°C to 1450°C.

[0011] In some embodiments, the position data S ranges from -10 mm to 10 mm.

[0012] In some embodiments, when entering the temperature stabilization step, the crucible position is adjusted to a preset liquid level distance position.

[0013] In some embodiments, the temperature data T is obtained through a first measurement point, and the first measurement point is located at the pulling head.

[0014] In some embodiments, the position data is obtained through a second measuring point, and the second measuring point is located at the pulling head.

[0015] In some embodiments, the first measurement point is a laser detection point.

[0016] In some embodiments, the second measurement point is a laser detection point.

[0017] In some embodiments, the surface temperature data T of the silicon melt is obtained by multi-point measurement.

[0018] In some embodiments, the guide tube position data S is obtained through multi-point measurement.

[0019] In some embodiments, the initial value of the position data of the guide tube is the distance between the lower edge of the guide tube and the surface of the silicon melt.

[0020] In some embodiments, the temperature data T and the position data S obtained at the measurement point are fed back to a processor.

[0021] In some embodiments, the processor adjusts the position of the crucible according to a first difference ΔT between the temperature data T and the preset temperature data T0 and a second difference ΔS between the position data S and the preset position data S0. Beneficial effects

[0022] The present application provides a method for controlling the liquid level distance of a Czochralski single crystal, comprising: measuring the surface temperature of the silicon melt during the temperature stabilization process to obtain temperature data T of the silicon melt; obtaining position data S of a guide tube when the difference ΔT between the temperature data T and a preset temperature T0 is between 10°C and 50°C; obtaining a first difference from the temperature data T and the preset temperature data, and obtaining a second difference from the position data S and the preset position data; and adjusting the position of the crucible based on the first difference ΔT and the second difference ΔS. By setting measurement points and the positional relationship between the temperature data and the guide tube, the present application ensures that the liquid level distance is accurately controlled according to process requirements, thereby meeting the temperature gradient requirements for Czochralski single crystal production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0024] FIG1 is a schematic diagram of the structure of the device used for crystal pulling in the embodiment of the present application;

[0025] Description of the drawings: 1- single crystal furnace, 101- first measuring point, 102- second measuring point, 2- inner guide tube, 3- outer guide tube, 4- crucible, 5- surface of silicon melt.

[0026] Implementation Methods of the Application

[0027] The following will provide a clear and complete description of the technical solutions in the embodiments of the present application, in conjunction with the embodiments of the present application. It should be noted that the embodiments described are only a portion of the embodiments of the present application, and are not intended to be exhaustive. All other embodiments derived by persons skilled in the art based on the embodiments of the present application without inventive effort are intended to fall within the scope of protection of the present application. Furthermore, in the description of the present application, the term "including" means "including but not limited to." The terms "first," "second," and "third," etc., are used merely as designations and do not impose numerical requirements or establish an order. Various embodiments of the present application may be presented in the form of a range. It should be understood that describing in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application. Therefore, the range description should be considered to specifically disclose all possible subranges and individual numerical values ​​within the range. For example, a range description of 1 to 6 should be considered to specifically disclose subranges, such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., as well as individual numerical values ​​within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range.

[0028] As shown in Figure 1, the equipment used for the growth of single crystal silicon described in this application includes a single crystal furnace 1, an inner guide tube 2 and an outer guide tube 3 arranged above a crucible 4, the crucible 4 contains molten silicon melt, and the single crystal silicon 1 grows upward from the surface 5 of the silicon melt.

[0029] The single crystal of the present application is located within a single crystal growth apparatus, which also includes a pulling head on which a seed crystal is mounted. During the single crystal growth process, the pulling head gradually pulls the seed crystal, causing the molten silicon in crucible 4 to gradually solidify and form a single crystal. A first measurement point 101 and a second measurement point 102 are provided on the pulling head. These measurement points rise as the pulling head is raised, enabling real-time monitoring of parameter information that needs to be controlled during the single crystal growth process, and better reflecting parameter changes during the single crystal growth process.

[0030] In some embodiments, the first measurement point 101 and the second measurement point 102 are laser measurement points. In some embodiments, the temperature data T and position data S of the present application are obtained through multi-point measurement. For example, in a specific application example, the multi-point measurement method is to measure 9 points in 360 degrees. The measurement signal sensor obtained from the first and second measurement points displays the value, and the 9-point average is used as the value. For example, the position of the guide tube is calculated by the distance difference between the laser light source and the object. This covers 360 degrees of multi-point detection and calculation, and is not affected by other factors such as abnormal crystal diameter, which may cause inaccurate collected data.

[0031] The embodiments of the present application provide a method for controlling the liquid level distance of a Czochralski single crystal, comprising: measuring the surface temperature of the silicon melt in the crucible when entering the temperature stabilization process, obtaining temperature data T of the silicon melt surface; obtaining a first difference ΔT from the temperature data T and the preset temperature data T0, and obtaining position data S of the guide tube when the first difference ΔT is in the range of 10°C to 50°C; obtaining a second difference ΔS from the position data S and the preset position data S0; and adjusting the position of the crucible based on the first difference ΔT and the second difference ΔS. The present application monitors the difference between the liquid level of the silicon melt and the initial data during the crystal pulling process based on the difference between the temperature data of the silicon melt surface and the preset temperature when the temperature data difference deviates, and adjusts the relationship between the actual silicon melt liquid level and the preset liquid level in real time, so that the actual liquid level and the preset liquid level maintain a dynamic balance, ensuring that the liquid level is accurately controlled according to process requirements and meeting the crystal pulling process requirements.

[0032] In some embodiments, the value of the acquired temperature data T is any value among 1400, 1410, 1420, 1430, 1440, 1450 or a range consisting of any two values, for example, the range of the temperature data T is 1410°C to 1430°C.

[0033] In some embodiments, the preset temperature T0 ranges from 1400° C. to 1410° C., and the temperature data T ranges from 1410° C. to 1430° C. In some embodiments, the first difference ΔT ranges from 10° C. to 30° C. For example, the first difference ΔT can be any value among 10, 20, 30, or a range between any two values.

[0034] The present application obtains silicon melt surface temperature data through the first measuring point 101. When the temperature data and the preset temperature data are within a reasonable deviation range, there is no need to adjust the liquid level distance of the silicon melt.

[0035] In some embodiments, as shown in FIG. 1 , the position data S is the distance between the lower edge of the inner guide tube 2 and the surface 5 of the silicon melt.

[0036] In this application, the position data S is obtained by real-time monitoring of the second measuring point 102. In some embodiments, the position data S has position preset data S0, and the initial position data S0 is the distance H0mm between the inner guide tube 2 and the initial position of the silicon melt surface 5.

[0037] In some embodiments, the second difference ΔS is in the range of -10 mm to 10 mm. For example, the second difference ΔS can be any value among -10, -5, 0, 5, 10, or a range consisting of any two values.

[0038] In some embodiments, when the temperature data T is in the range of 1410°C to 1430°C, the second measuring point 102 obtains the position data S between the lower edge of the inner guide tube 102 and the silicon melt surface 5. When the obtained position data S is within the second difference ΔS range defined in this application, there is no need to adjust the position of the crucible 4 and thus the position of the silicon melt surface.

[0039] In some implementations, if the real-time position information H1 obtained by the position data S satisfies the following relationship with the initial data H0: 0.95H0≤H1≤1.05H0, there is no need to perform the position adjustment of the crucible 4 .

[0040] The solution of the present application achieves real-time linkage between the surface temperature data of the silicon melt and the position data of the guide tube 2 within the distance from the surface of the silicon melt, thereby avoiding the situation where the position of the crucible 4 needs to be adjusted due to fluctuations in one parameter. The solution of the present application comprehensively considers the relationship between the position data and the temperature data. When the two data are within the range set in this application, the process requirements for single crystal silicon growth can be met, thereby improving the quality of the grown single crystal silicon.

[0041] In some specific embodiments, when entering the temperature stabilization process, the position of the crucible 4 is adjusted to a preset liquid level distance position, and the allowable deviation range between the position of the crucible 4 and the preset liquid level distance is -0.5 mm to 0.5 mm.

[0042] In some embodiments, the preset liquid level distance is the initial position of the surface 5 of the silicon melt in the crucible 4 .

[0043] In some embodiments, after the chemical process is completed and the temperature stabilization process begins, the silicon melt surface temperature is monitored through the first measuring point 101, and the temperature detection is maintained for 20 minutes to 30 minutes. When the silicon melt surface temperature tested at the first measuring point is between 1410°C and 1430°C, the measurement step of the second measuring point is executed.

[0044] In some embodiments, the second measuring point 102 measures the distance between the lower edge of the inner guide tube 2 and the silicon melt surface 5 to obtain position data S.

[0045] The obtained temperature data T and position data S are fed back to the sensor,

[0046] When the deviation between the position H1 of the position data S and the initial data H0 is greater than 0.05H0, the position of the crucible 4 is adjusted to achieve a position offset of the crucible 4 to meet the liquid level distance required by the present application.

[0047] Repeat the above steps until the equal diameter process is completed and stop the liquid level distance control.

[0048] In some embodiments, the processor in the present application is a PLC processor, which is communicatively connected to a control unit in the crucible 4 lifting mechanism. The crucible 4 lifting mechanism is used to control the position of the crucible 4. Specifically, the crucible 4 lifting mechanism includes a drive device, which includes a control unit. The control unit controls the position of the crucible 4 through signals fed back by the PLC. In some embodiments, the drive device can be a servo motor, and the control unit in the servo motor adjusts the position of the crucible 4 by controlling relevant parameters such as the servo motor's speed and output shaft diameter.

[0049] In some specific implementations, the detected temperature data T is within the range of 1420±10°C, triggering the measurement function of the second measurement point 102. The temperature data T and position data S obtained at the measurement point are calculated and fed back to the PCL system as the average value for the next adjustment.

[0050] In some embodiments, the position offset relationship between the inner guide tube 2 and the crucible 4 and the adjustment relationship between the temperature data T are such that the difference between the temperature data T and the preset temperature T0 is within the range of 10°C to 15°C, corresponding to an adjustment of the crucible 4 position offset of 1mm to 1.5mm.

[0051] In some embodiments, the crucible 4 position adjustment distance H2 mm is: H2 = ΔT / 10, where ΔT is the difference between the surface temperature of the silicon melt and the preset temperature, in degrees Celsius.

[0052] In some specific implementations, the liquid level is controlled by:

[0053] When the temperature data of the silicon melt surface obtained at the first measuring point 101 is 1420° C., the preset temperature T0 is 1400° C., and ΔT is 20° C., the data measurement at the second measuring point 102 is triggered.

[0054] The value of the preset data S0 of the position of the inner flow tube 2 is H0mm, and the obtained position data S is H1mm. The difference between H1mm and H0mm is 11mm. At this time, the deviation of the position data S is outside the range limited by ΔS. It is necessary to lower the surface temperature of the silicon melt to below 1410°C by adjusting the position of the crucible 4. The position of the crucible 4 is adjusted downward. After adjustment, the second difference ΔS is within the range of -10mm to 10mm.

[0055] After the adjustment is completed, the range of the temperature data T is continuously detected. When the temperature data is below the range of 1410° C. set in this application, there is no need to adjust the position of the crucible 4 again.

[0056] This application is for a CZ method crystal growth liquid level control method. By comparing detected data with a preset liquid level height, the automatically interlocking crucible 4 system automatically raises and lowers the crucible, maintaining a dynamic balance between the actual liquid level and the preset liquid level. The actual liquid level meets the crystal pulling process requirements and ensures the temperature gradient requirements of MCZ method IGBT products. In addition, in some embodiments, data acquired through laser measurement points can cover 360 degrees of multi-point detection and calculation, and is not affected by other factors such as abnormal crystal diameter, which may lead to inaccurate collected data.

[0057] The present application can avoid the change in V / G due to the temperature gradient change caused by the inconsistency between the liquid level distance and the process requirements, which can induce OISF COP defects and even broken bud problems. The present application can also avoid the change in temperature field caused by the inconsistency between the liquid level distance and the process requirements, which can induce the deviation of quality parameters such as RRV (cross-sectional uniformity) and ORG (oxygen radial gradient). The device for controlling the liquid level distance of the vertically pulled single crystal has a simple structure, is automated, and has high accuracy. Compared with manual operation, it reduces errors and human errors. This method can realize an automated working mode that replaces manual operation, has a high safety factor and high accuracy, and can effectively control the frequency of crystal defects.

[0058] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0059] The above is a detailed introduction to a method for controlling the liquid level distance of a Czochralski single crystal provided in an embodiment of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, based on the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for controlling the liquid level distance of a CZ single crystal, comprising: When entering the temperature stabilization process, the temperature of the surface of the silicon melt in the crucible is measured to obtain the temperature data T of the surface of the silicon melt; Obtain a first difference ΔT through the temperature data T and the preset temperature data T0, and when the first difference ΔT is in the range of 10° C. to 50° C., obtain position data S of the guide tube; Obtaining a second difference ΔS through the position data S and the preset position data S0; Based on the first difference ΔT and the second difference ΔS, the position of the crucible is adjusted.

2. The method for controlling the liquid level distance of a CZ single crystal according to claim 1, wherein: The temperature data T ranges from 1400°C to 1450°C.

3. The method for controlling the liquid level distance of a CZ single crystal according to claim 1, wherein: The second difference ΔS ranges from -10 mm to 10 mm.

4. The method for controlling the liquid level distance of a CZ single crystal according to claim 1, wherein: When entering the temperature stabilization step, the position of the crucible is adjusted to a preset liquid level distance position.

5. The method for controlling the liquid level distance of a CZ single crystal according to claim 1, wherein: The temperature data T is obtained through a first measuring point, and the first measuring point is located at the pulling head.

6. The method for controlling the liquid level distance of a CZ single crystal according to claim 5, wherein: The position data S is obtained through a second measuring point, and the second measuring point is located at the pulling head.

7. The method for controlling the liquid level distance of a CZ single crystal according to claim 6, wherein: The first measurement point is a laser detection point.

8. The method for controlling the liquid level distance of a CZ single crystal according to claim 6, wherein: The second measuring point is a laser detection point.

9. The method for controlling the liquid level distance of a CZ single crystal according to claim 1, wherein: The surface temperature data T of the silicon melt is obtained by multi-point measurement.

10. The method for controlling the liquid level distance of a CZ single crystal according to claim 1, wherein: The guide tube position data S is obtained through multi-point measurement.

11. The method for controlling the liquid level distance of a CZ single crystal according to claim 1, wherein: The initial value of the position data of the guide tube is the distance between the lower edge of the guide tube and the surface of the silicon melt.

12. The method for controlling the liquid level distance of a CZ single crystal according to claim 1, wherein: The temperature data T and the position data S obtained at the measuring point are fed back to the processor.

13. The method for controlling the liquid level distance of a CZ single crystal according to claim 12, wherein: The processor adjusts the position of the crucible according to a first difference ΔT between the temperature data T and the preset temperature data T0 and a second difference ΔS between the position data S and the preset position data S0.

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