A high-precision liquid mouth distance measurement method

Abstract

The present invention provides a high-precision liquid mouth distance measurement method. The following steps are included: fix the position of the visual detection part so that the visual detection part obtains the image of the characteristic point P1 of the reflection of the characteristic point of the lower edge of the guide tube in the single crystal furnace on the surface of the silicon melt; fix a reference liquid mouth distance value, at this time the pixel coordinate value corresponding to the reflection characteristic point P1 is Y1; the crucible is displaced up and down, and the distance of each displacement is Δmm, and the pixel value Y1′ corresponding to the characteristic point P1′ is obtained. The near-linear scatter function relationship of Y1′=F(Δmm); the slope K value is obtained based on the near-linear scatter function relationship, so as to calculate the change value ΔGap of the liquid mouth distance, and then the measured liquid mouth distance is calculated, and the calculation formula is: measured liquid mouth distance=ΔGap+reference liquid mouth distance value. Based on this method, when conducting a measurement experiment under a fixed liquid mouth distance value, the liquid mouth distance measurement accuracy within an average error of 0.5mm can be achieved, thereby controlling the quality of the single crystal silicon rod.

Description

Technical Field

[0001] The invention belongs to the technical field of single crystal silicon preparation, and in particular relates to a high-precision liquid mouth distance measurement method. Background Art

[0002] Silicon crystal is an important raw material for the modern microelectronics industry, and its precision and stability have a direct impact on the quality of the product. During the processing, the liquid mouth distance of the silicon crystal is a crucial parameter that affects the quality of crystal growth. The liquid mouth distance (melt gap) is defined as the distance between the lower edge of the guide tube in the single crystal furnace and the surface of the silicon melt in the crucible of the single crystal furnace. Its change will affect the quality of the crystal rod. If the liquid mouth distance is too small, it will affect the temperature distribution inside the crystal furnace, resulting in uneven melting temperature, instability in the operation of the crystal furnace, and thus reduce the quality of the crystal rod. If the liquid mouth distance is too large, it will affect the carbon and oxygen content in the crystal rod, forming carbon atomic substitution or oxygen interstitial impurities in the crystal rod. Therefore, the liquid mouth distance greatly affects the growth rate, appearance shape, and physical quality of the crystal rod. The accurate liquid mouth distance value can play a positive feedback role in the pulling speed and pot lifting speed of the crystal rod, which can correct the parameters of the crystal pulling process, optimize the production process, and improve product quality. Therefore, in the process of single crystal silicon production, the liquid mouth distance should be more accurately regulated according to actual needs.

[0003] Due to the high temperature in the single crystal furnace and the extremely high requirements for environmental cleanliness, it is difficult to directly measure the liquid-to-mouth distance in the single crystal furnace with existing material technology. At present, the setting of the liquid-to-mouth distance mostly relies on the observation and judgment of experienced operators. Different people have different judgment methods for measuring the liquid-to-mouth distance in the single crystal furnace, which will bring errors to the observation of the liquid-to-mouth distance.

[0004] Therefore, how to achieve accurate measurement and control of the liquid mouth distance is one of the key issues that technical personnel in this field need to solve urgently. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a high-precision liquid-to-mouth distance measurement method. The present invention designs a high-precision liquid-to-mouth distance measurement method. Based on this method, when conducting a measurement experiment under a fixed liquid-to-mouth distance value, the liquid-to-mouth distance measurement accuracy within an average error of 0.5 mm can be achieved, thereby controlling the quality of the single crystal silicon rod.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a high-precision liquid nozzle distance measurement method, which is applied to a single crystal furnace. The single crystal furnace includes an upper furnace drum, a guide tube and a crucible arranged up and down, and a visual inspection component is arranged above the upper furnace drum.

[0008] The liquid port distance measurement method comprises the following steps:

[0009] (1) Fix the position of the visual inspection component so that the visual inspection component can obtain an image of a characteristic point P1 reflected on the surface of the silicon melt by a characteristic point at the lower edge of the guide tube in the single crystal furnace.

[0010] (2) A reference liquid mouth distance value is fixed, at which the Y-axis value of the pixel coordinate corresponding to the reflection feature point P1 is Y1; the crucible moves up and down, and the distance of each displacement is Δmm, and the pixel value corresponding to the feature point P1' is obtained, and the near-linear scatter function relationship of Y1'=F(Δmm) is obtained.

[0011] (3) Based on the near-linear scatter function relationship, the slope K value is obtained to calculate the change value ΔGap of the liquid mouth distance, and then the measured liquid mouth distance is calculated. The calculation formula is: measured liquid mouth distance = ΔGap + reference liquid mouth distance value.

[0012] The present invention designs a high-precision liquid nozzle distance measurement method. Based on this method, when conducting a measurement experiment under a fixed liquid nozzle distance value, the liquid nozzle distance measurement accuracy within an average error of 0.5 mm can be achieved, thereby controlling the quality of single crystal silicon rods.

[0013] It should be noted that the molten silicon is located inside the crucible.

[0014] Preferably, an imaging line irradiated by the visual detection component onto the surface of the silicon melt intersects with a center line where the upper furnace drum, the guide tube and the crucible are located.

[0015] Preferably, the visual detection component is a CCD camera.

[0016] It should be noted that a CCD (Charge-Coupled Device) camera is a charge-coupled device camera. It is a camera that uses CCD as an image sensor. CCD is a semiconductor device that can convert optical images into digital signals. When light passes through the lens and shines on the CCD chip, the photons will excite the charges in the chip. These charges will be collected and converted into electrical signals, and then after a series of processing, a digital image will be formed.

[0017] Preferably, the value range of Δmm is: -5mm≤Δmm≤5mm, for example, the value of Δmm is 1mm, 2mm, 3mm, 4mm or 5mm.

[0018] In the present invention, selecting a suitable Δmm value helps to improve the accuracy of the K value, thereby improving the measurement accuracy of the liquid port distance.

[0019] It should be noted that the positive and negative signs represent different directions of the crucible displacement.

[0020] Preferably, the number of the reflection feature points P1 is at least 2, for example, 2, 3 or 5.

[0021] In the present invention, based on the positions of different reflection feature points P1, the slope K value will be different but still in a nearly linear relationship. According to the actual crystal growth situation, different feature points (i.e., at least 2) can be selected to obtain the corresponding K value, thereby calculating the corresponding Gap value.

[0022] Preferably, the near-linear scatter function relationship is:

[0023] Y1'=K×Δmm+Y1.

[0024] Preferably, the calculation formula of ΔGap is:

[0025] ΔGap=|P1'-P1|×K.

[0026] Preferably, the ΔGap satisfies the following conditions:

[0027] If ΔGap is greater than the tolerance error, the crucible is controlled to move so that ΔGap is less than the tolerance error; if ΔGap is less than the tolerance error, the requirement is met.

[0028] It should be noted that the lifting direction of the crucible's displacement depends on the positive or negative value of (P1'-P1)×K, and the lifting distance is equal to |P1'-P1|×K.

[0029] Preferably, the tolerance error is 0-0.25 mm, for example, it may be 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm or 0.25 mm.

[0030] Preferably, the liquid mouth distance measurement method comprises the following steps:

[0031] (1) The position of the CCD camera is fixed so that the CCD camera can obtain an image of a characteristic point P1 reflected on the surface of the silicon melt by a characteristic point at the lower edge of the guide tube in the single crystal furnace.

[0032] (2) A reference liquid mouth distance value is fixed, at which the pixel coordinate Y-axis value corresponding to the reflection feature point P1 is Y1; the crucible rises dynamically, and each rising distance is Δmm, and a near-linear scatter function relationship of Y1′=F(Δmm) is obtained for the pixel value corresponding to the feature point P1′.

[0033] Among them, the value range of Δmm is: -5mm≤Δmm≤5mm; the near-linear scatter function relationship is: Y1'=K×Δmm+Y1.

[0034] (3) Based on the near-linear scatter function relationship, the slope K value is obtained to calculate the change value ΔGap of the liquid mouth distance, and then the measured liquid mouth distance is calculated. The calculation formula is: measured liquid mouth distance = ΔGap + reference liquid mouth distance value.

[0035] Among them, the calculation formula of the ΔGap is: ΔGap=|P1'-P1|×K; the ΔGap satisfies the following conditions: if ΔGap is greater than the tolerance error, the PID system is called to control the crucible to rise and fall so that ΔGap is less than the tolerance error; if ΔGap is less than the tolerance error, the requirement is met; the tolerance error is 0-0.25mm.

[0036] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention designs a high-precision liquid nozzle distance measurement method. Based on this method, when conducting a measurement experiment under a fixed liquid nozzle distance value, the liquid nozzle distance measurement accuracy within an average error of 0.5 mm can be achieved, thereby controlling the quality of single crystal silicon rods. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic structural diagram of a liquid port distance testing device provided by the present invention.

[0040] Figure 2 The K value calculated in Examples 1-1 to 1-7 and Examples 2-1 to 2-7 of the present invention at different liquid outlet distances is shown in FIG.

[0041] Figure 3 This is a bar chart comparing the measured liquid port distance and the reference liquid port distance calculated when the reference liquid port distance is set between 45 mm and 55 mm in the present invention.

[0042] Among them, 1-CCD camera; 2-upper furnace tube; 3-guide tube; 4-crucible. DETAILED DESCRIPTION

[0043] It should be clear that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0044] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described at the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0045] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0046] See also Figure 1 In the following implementation manner, a single crystal furnace for growing single crystal silicon includes an upper furnace tube, a guide tube and a crucible arranged in an upper and lower manner, wherein molten silicon is contained in the crucible; a CCD camera is arranged above the upper furnace tube, and an imaging line irradiated by the CCD camera to the surface of the molten silicon intersects with a center line where the upper furnace tube, the guide tube and the crucible are located.

[0047] Example 1

[0048] This embodiment provides a high-precision liquid mouth distance measurement method, comprising the following steps:

[0049] (1) The position of the CCD camera is fixed so that the CCD camera can obtain an image of a characteristic point P1 reflected on the surface of the silicon melt by a characteristic point at the lower edge of the guide tube in the single crystal furnace.

[0050] (2) A reference liquid mouth distance value is fixed at 70 mm. At this time, the Y-axis value of the pixel coordinate corresponding to the reflection feature point P1 is Y1, and the X-axis value of the pixel coordinate is X1, that is, the pixel coordinate (2018.642, 1960.505); the crucible rises dynamically, and the distance of each rise is Δmm, Δmm is 5mm, and a pixel coordinate (Y1', X1') is obtained after each rise of Δmm, thereby drawing a near-linear scatter function relationship of the pixel value Y1'=F(Δmm) corresponding to the feature point P1'; until the reference liquid mouth distance value is fixed at 40 mm.

[0051] The near-linear scatter function relationship is: Y1'=K×Δmm+Y1.

[0052] (3) Based on the near-linear scatter function relationship, the slope K value is obtained to calculate the change value ΔGap of the liquid mouth distance, and then the measured liquid mouth distance is calculated. The calculation formula is: measured liquid mouth distance = ΔGap + reference liquid mouth distance value.

[0053] The calculation formula of ΔGap is: ΔGap=|P1'-P1|×K; ΔGap satisfies the following conditions: if ΔGap is greater than the tolerance error, the PID system is called to control the crucible to rise and fall so that ΔGap is less than the tolerance error; if ΔGap is less than the tolerance error, the requirement is met; the tolerance error is 0.2 mm.

[0054] The K value results calculated in the above Example 1 are shown in Table 1.

[0055] Table 1

[0056]

[0057] Example 2

[0058] This embodiment provides a high-precision liquid mouth distance measurement method, comprising the following steps:

[0059] (1) The position of the CCD camera is fixed so that the CCD camera can obtain an image of another characteristic point on the lower edge of the guide tube in the single crystal furnace, which is a reflection of a characteristic point P1 on the surface of the silicon melt.

[0060] (2) A reference liquid mouth distance value is fixed at 70 mm. At this time, the Y-axis value of the pixel coordinate corresponding to the reflection feature point P1 is Y1, and the X-axis value of the pixel coordinate is X1, that is, the pixel coordinate (2018.044, 1577.011; the crucible rises dynamically, and the distance of each rise is Δmm, Δmm is 5mm, and a pixel coordinate (Y1', X1') is obtained after each rise of Δmm, thereby drawing a near-linear scatter function relationship of the pixel value Y1'=F(Δmm) corresponding to the feature point P1'; until the reference liquid mouth distance value is fixed at 40 mm.

[0061] The near-linear scatter function relationship is: Y1'=K×Δmm+Y1.

[0062] (3) Based on the near-linear scatter function relationship, the slope K value is obtained to calculate the change value ΔGap of the liquid mouth distance, and then the measured liquid mouth distance is calculated. The calculation formula is: measured liquid mouth distance = ΔGap + reference liquid mouth distance value.

[0063] The calculation formula of ΔGap is: ΔGap=|P1'-P1|×K; ΔGap satisfies the following conditions: if ΔGap is greater than the tolerance error, the PID system is called to control the crucible to rise and fall so that ΔGap is less than the tolerance error; if ΔGap is less than the tolerance error, the requirement is met; the tolerance error is 0.2 mm.

[0064] The K value results calculated in the above Example 2 are shown in Table 2.

[0065] Table 2

[0066]

[0067] Figure 2 The variation curve of the K value calculated by Example 1 and Example 2 at different liquid outlet distances is shown. It can be seen from the figure that the K value will be different when different physical feature points are selected, but the change between the pixel value and the liquid outlet distance is still in a nearly linear relationship; therefore, based on the actual thermal field conditions, selecting different physical reflection feature points will not affect the linear relationship between the liquid outlet distance and the pixel value measured by the CCD camera. At the same time, selecting the corresponding K value based on the requirements under different set liquid outlet distances can improve the measurement accuracy.

[0068] Among them, according to the liquid mouth distance measurement method described in Example 1, the crucible is slowly moved up and down, so that the reference liquid mouth distance is 45mm, 46mm, 47mm, 48mm, 49mm, 50mm, 51mm, 52mm, 53mm, 54mm and 55mm respectively, the measured liquid mouth distance is obtained based on the CCD camera, and the measurement accuracy is calculated, the measurement accuracy = measured liquid mouth distance - reference liquid mouth distance.

[0069] The above measurement and settlement results are as follows Figure 3 As shown in Table 3

[0070] Table 3

[0071]

[0072] Therefore, from Table 3 and Figure 3 It can be seen that this method can achieve a liquid nozzle distance measurement accuracy within an average error of 0.5 mm when conducting measurement experiments under a fixed liquid nozzle distance value, thereby controlling the quality of the single crystal silicon rod.

[0073] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A high-precision liquid mouth distance measurement method, characterized in that: The liquid mouth distance measurement method is applied to a single crystal furnace, wherein the single crystal furnace comprises an upper furnace drum, a guide tube and a crucible arranged in a vertical direction, and a visual detection component is arranged above the upper furnace drum; The liquid port distance measurement method comprises the following steps: (1) Fixing the position of the visual inspection component so that the visual inspection component obtains an image of a characteristic point P1 reflected on the surface of the silicon melt by a characteristic point at the lower edge of the guide tube in the single crystal furnace; (2) A reference liquid port distance value is fixed, at which the Y-axis value of the pixel coordinate corresponding to the reflection feature point P1 is Y1; the crucible is displaced up and down, and the distance of each displacement is Δmm, and a near-linear scatter function relationship of the pixel value Y1′=F(Δmm) corresponding to the feature point P1′ is obtained; (3) Based on the near-linear scatter function relationship, the slope K value is obtained to calculate the change value ΔGap of the liquid mouth distance, and then the measured liquid mouth distance is calculated. The calculation formula is: measured liquid mouth distance = ΔGap + reference liquid mouth distance value.

2. The method for measuring the liquid mouth distance according to claim 1, characterized in that: The imaging line irradiated by the visual detection component onto the surface of the silicon melt intersects with the center line where the upper furnace tube, the guide tube and the crucible are located.

3. The method for measuring the liquid mouth distance according to claim 1 or 2, characterized in that: The visual detection component is a CCD camera.

4. The method for measuring the liquid mouth distance according to any one of claims 1 to 3, characterized in that: The value range of Δmm is: -5mm≤Δmm≤5mm.

5. The method for measuring the liquid mouth distance according to any one of claims 1 to 4, characterized in that: The number of the reflection feature points P1 is at least 2.

6. The method for measuring the liquid mouth distance according to any one of claims 1 to 5, characterized in that: The near-linear scatter function relationship is: Y1'=K×Δmm+Y1.

7. The method for measuring the liquid mouth distance according to any one of claims 1 to 6, characterized in that: The calculation formula of ΔGap is: ΔGap=|P1'-P1|×K.

8. The method for measuring the liquid mouth distance according to any one of claims 1 to 7, characterized in that: The ΔGap satisfies the following conditions: If ΔGap is greater than the tolerance error, the crucible is controlled to move so that ΔGap is less than the tolerance error; if ΔGap is less than the tolerance error, the requirement is met.

9. The method for measuring the liquid mouth distance according to any one of claims 1 to 8, characterized in that: The tolerance error is 0-0.25mm.

10. The method for measuring the liquid mouth distance according to any one of claims 1 to 9, characterized in that: The liquid port distance measurement method comprises the following steps: (1) Fixing the position of the CCD camera so that the CCD camera can obtain an image of a characteristic point P1 reflected on the surface of the silicon melt by a characteristic point at the lower edge of the guide tube in the single crystal furnace; (2) A reference liquid mouth distance value is fixed, at which the Y-axis value of the pixel coordinate corresponding to the reflection feature point P1 is Y1; the crucible rises dynamically, and the distance of each rise is Δmm, and a near-linear scatter function relationship of the pixel value Y1′=F(Δmm) corresponding to the feature point P1′ is obtained; The value range of Δmm is: -5mm≤Δmm≤5mm; the relationship of the near-linear scatter function is: Y1'=K×Δmm+Y1; (3) Based on the near-linear scatter function relationship, the slope K value is obtained to calculate the change value ΔGap of the liquid mouth distance, and then the measured liquid mouth distance is calculated. The calculation formula is: measured liquid mouth distance = ΔGap + reference liquid mouth distance value; Among them, the calculation formula of the ΔGap is: ΔGap=|P1'-P1|×K; the ΔGap satisfies the following conditions: if ΔGap is greater than the tolerance error, the PID system is called to control the crucible to rise and fall so that ΔGap is less than the tolerance error; if ΔGap is less than the tolerance error, the requirement is met; the tolerance error is 0-0.25mm.

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