A method and system for cutting a boule

Abstract

The application belongs to the technical field of semiconductor. In view of the problem that the existing crystal bar needs to be measured for resistivity for multiple times to obtain a qualified crystal bar meeting the requirements during cutting, and the efficiency is low, the application discloses a crystal bar cutting method and system, which can calculate the resistivity of different positions of a to-be-measured crystal bar according to the remaining material amount in a pot, and obtain the position information corresponding to the to-be-measured crystal bar through a crystal pulling subsystem of a single crystal furnace, so that when the calculated resistivity meets the minimum value requirement of a preset target resistivity, the effective length of the to-be-measured crystal bar can be obtained, and a qualified crystal bar can be obtained through one-time cutting, and the working efficiency is greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor, and particularly relates to a method and system for cutting a crystal bar. BACKGROUND

[0002] The resistivity is a main technical index of the crystal bar, and the control of the resistivity of the crystal bar is controlled according to the concentration of the dopant.

[0003] At present, the manufacturers mostly adopt the method of first measuring the resistivity of the surface of the crystal bar to determine the approximate length of the qualified crystal bar, and then cutting the crystal bar to obtain the qualified crystal bar.

[0004] However, the above method needs to measure the resistivity of the crystal bar for multiple times and cut the crystal bar for multiple times to obtain the qualified crystal bar meeting the requirements, and the time required is long, and the manual detection inevitably has errors, thereby affecting the accuracy of the measurement of the resistivity of the crystal bar. SUMMARY

[0005] In view of the problems that the time required is long and the result is inaccurate when the resistivity is detected manually and the crystal bar is cut to obtain the qualified crystal bar, one of the purposes of the application is to provide a method and system for cutting a crystal bar to realize the rapid measurement of the resistivity of the crystal bar and cut the crystal bar once to obtain the qualified crystal bar.

[0006] To achieve the above purpose, the application adopts the following technical scheme:

[0007] A method for measuring the resistivity of a crystal bar, comprising the following steps:

[0008] S1, calculating a first dopant concentration according to the relationship between the weight of the polycrystalline silicon raw material and the weight of the master alloy;

[0009] S2, obtaining the remaining material amount in the pot and calculating the weight of the crystal bar to be measured according to the remaining material amount;

[0010] S3, calculating the second dopant concentration of different positions of the crystal bar to be measured according to the relationship between the weight of the crystal bar to be measured and the calculated first dopant concentration;

[0011] S4, calculating the resistivity of different positions of the crystal bar to be measured according to the relationship between the second dopant concentration and the resistivity;

[0012] S5, comparing the calculated resistivity with a target resistivity, and when the calculated resistivity meets the requirement of the minimum value of the target resistivity, obtaining the position information of the crystal bar to be measured to determine the effective length of the crystal bar to be measured and cut, thereby obtaining the qualified crystal bar.

[0013] Preferably, calculating the first dopant concentration based on the relationship between the weight of the polycrystalline silicon raw material and the weight of the master alloy includes: using the formula

[0014]

[0015] Calculate the concentration of the first dopant; where M is the weight of the master alloy; W is the weight of the polycrystalline silicon raw material; N3 is the impurity concentration of the master alloy; N1 is the concentration of the first dopant; and K is the segregation coefficient of the impurity in silicon.

[0016] Preferably, calculating the first dopant concentration based on the relationship between the weight of the polycrystalline silicon raw material and the weight of the master alloy includes:

[0017] Using formula

[0018] Calculate the concentration of the first dopant; where N1 is the concentration of the first dopant; M is the weight of the master alloy; and W is the weight of the polysilicon raw material.

[0019] Preferably, calculating the weight of the crystal rod to be tested based on the amount of remaining material includes:

[0020] Using formula

[0021]

[0022] Calculate the weight of the crystal rod to be tested; where G is the weight of the crystal rod to be tested; M is the weight of the master alloy; W is the weight of the polycrystalline silicon raw material; and T is the amount of material remaining in the pot.

[0023] Preferably, the step of calculating the second dopant concentration at different locations on the crystal rod under test based on the relationship between the weight of the crystal rod and the calculated first dopant concentration includes:

[0024] Using formula

[0025] Calculate the concentration of the second dopant; where N2 is the concentration of the second dopant; N1 is the concentration of the first dopant; K is the segregation coefficient of the impurity in silicon; and g is the ratio of the weight of the test crystal rod to the total weight of the polycrystalline silicon raw material and the master alloy.

[0026] Preferably, the calculation of the resistivity at different locations of the test ingot based on the relationship between the second dopant concentration and resistivity includes:

[0027] When the crystal rod to be tested is a P-type crystal rod, the formula is used.

[0028] Calculate the resistivity of the crystal rod to be tested;

[0029] When the crystal rod to be tested is an N-type crystal rod, the formula is used.

[0030] Calculate the resistivity of the crystal rod to be tested;

[0031] Where ρ is resistivity; N2 is the concentration of the second dopant;

[0032] ;

[0033] A0=-3.0769, A1=2.2108, A2=-0.62272, A3=0.057501, B1=-0.68157, B2=0.19833, B3=-0.018376. This application also discloses a crystal rod cutting system, signal-connected to the crystal pulling subsystem of a single crystal furnace, comprising: a weighing subsystem for measuring the amount of material remaining in the pot; a calculation subsystem, signal-connected to the weighing subsystem and the crystal pulling subsystem, for calculating the resistivity of the crystal rod to be tested based on the amount of material remaining measured by the weighing subsystem; and a cutting subsystem, signal-connected to the calculation subsystem, which can determine the effective length of the crystal rod to be tested based on the resistivity calculated by the calculation subsystem and the position information of the crystal rod to be tested in the crystal pulling subsystem, and cut the crystal rod to obtain a qualified crystal rod.

[0034] Preferably, the computing subsystem includes:

[0035] The first calculation module is used to calculate the first dopant concentration based on the weight of the polysilicon raw material and the weight of the master alloy.

[0036] The second calculation module is connected to the weighing subsystem and is used to calculate the weight of the crystal rod to be tested based on the amount of remaining material.

[0037] The third calculation module is used to calculate the second dopant concentration based on the first dopant concentration and the weight of the crystal rod to be tested;

[0038] The first acquisition module is used to acquire the formula relating the dopant concentration and resistivity of the crystal rod under test.

[0039] The fourth calculation module is used to calculate the resistivity of the crystal rod under test based on the relationship formula of the first acquisition module and the second dopant concentration of the third calculation module.

[0040] Preferably, the calculation subsystem further includes a second acquisition module; when the resistivity obtained by the fourth calculation module meets the minimum value requirement of the preset target resistivity, the second acquisition module acquires the position information of the crystal rod to be tested in the crystal pulling subsystem, so as to obtain the effective length of the crystal rod to be tested and store it.

[0041] Preferably, the cutting subsystem includes a transfer device for transferring the crystal rod to be tested; a length detection device for visually scanning the crystal rod to be tested placed on the transfer device to measure its length and determine the cutting position of the crystal rod to be tested based on its effective length; and a cutting device that is signal-connected to the length detection device and can cut the crystal rod to be tested based on the cutting position determined by the length detection device.

[0042] As can be seen from the above description, the beneficial effects of this application compared with the prior art are:

[0043] The resistivity at different positions of the crystal rod under test can be calculated by measuring the amount of material remaining in the pot. This resistivity can then be compared with the preset target resistivity. When the minimum target resistivity requirement is met, the position information of the crystal rod under test is obtained through the crystal pulling system, thereby obtaining the effective length of the crystal rod under test. The crystal rod under test is then cut according to the effective length to obtain a qualified crystal rod. This method only requires one cut to obtain a qualified crystal rod, which greatly improves work efficiency. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic flowchart of the crystal rod cutting method according to an embodiment of this application.

[0046] Figure 2 This is a schematic diagram of the truncation subsystem in an embodiment of this application.

[0047] Figure 3 This is a schematic diagram of the cutting device according to an embodiment of this application.

[0048] Reference numerals: 1-Weighing subsystem; 2-Calculation subsystem; 21-First calculation module; 22-Second calculation module; 23-Third calculation module; 24-First acquisition module; 25-Fourth calculation module; 26-Second acquisition module; 3-Cutting subsystem; 31-Transfer device; 32-Length measuring device; 321-Marking unit; 33-Cutting device; 331-Cutter unit; 332-Position sensor. Detailed Implementation

[0049] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0050] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0053] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0054] Resistivity is a key technical indicator of a crystal rod, and its control is based on the concentration of dopant. The distribution of dopant in a single-crystal silicon rod is determined by the segregation mechanism. Different impurities have different segregation coefficients in silicon, which determines the different distributions of impurities in the rod during crystal growth, thus leading to different resistivity at different locations on the rod. In quasi-static growth processes with low crystal growth rates, the growth process can be approximated as a one-dimensional model. Therefore, the distribution of impurities in the crystal can be represented by the following formula:

[0055] Where, N L N is the concentration of impurities in the crystal rod when it grows to a length of L. 母 is the concentration of impurities in the mother liquor when the crystal rod is fully melted, and g is the ratio of the weight of the crystal rod when it grows to length L to the weight of the mother liquor when the crystal rod is fully melted.

[0056] The impurity concentration at different locations on a single-crystal silicon rod can be calculated using the above formula, and the resistivity distribution of the rod can be calculated based on the relationship between impurity concentration and resistivity.

[0057] Therefore, this application discloses a method for cutting a crystal rod, as shown in the attached figure. Figure 1 As shown, it includes the following steps:

[0058] S1. Calculate the concentration N1 of the first dopant based on the relationship between the weight W of the polycrystalline silicon raw material and the weight M of the master alloy.

[0059] S2. Obtain the amount of material remaining in the pot, T, and calculate the weight G of the crystal rod to be tested based on the amount of material remaining, T.

[0060] S3. Calculate the second dopant concentration N2 at different positions of the crystal rod under test based on the relationship between the weight G of the crystal rod and the calculated first dopant concentration N1.

[0061] S4. Calculate the resistivity ρ at different positions of the crystal rod under test based on the relationship between the second dopant concentration N1 and the resistivity.

[0062] S5. Based on the comparison between the calculated resistivity and the target resistivity, determine the effective length of the crystal rod to be tested and cut it to obtain a qualified crystal rod.

[0063] More specifically, step S1 includes using formula (1)

[0064]

[0065] Calculate the concentration of the first dopant. Where K is the segregation coefficient of the impurity in silicon.

[0066] In actual production, since the weight M of the master alloy is much smaller than the weight W of the polycrystalline silicon raw material, formula (2) can also be used in some embodiments.

[0067] Calculate the concentration of the first dopant.

[0068] In some embodiments, step S2 specifically includes using formula (3).

[0069]

[0070] Calculate the weight of the crystal rod to be tested.

[0071] In some embodiments, based on the segregation principle of silicon crystal production, step S3 utilizes formula (4).

[0072] Calculate the concentration of the second dopant. Where g is the ratio of the weight G of the test ingot, the weight W of the polycrystalline silicon raw material, and the weight M of the master alloy.

[0073] In some embodiments, since the crystal rods are of two types, P-type and N-type, and the resistivity-dopant concentration relationship is different for the two types of crystal rods, the relationship between dopant concentration and resistivity in step S4 can be selected according to the actual situation.

[0074] Specifically, when the crystal rod is P-type, formula (5) is used.

[0075] Calculate the resistivity of the crystal rod to be tested;

[0076] When the crystal rod is N-type, use formula (6).

[0077] Calculate the resistivity of the crystal rod to be tested; where,

[0078] , A0=-3.0769, A1=2.2108, A2=-0.62272, A3=0.057501, B1=-0.68157, B2=0.19833, B3=-0.018376.

[0079] In some embodiments, step S5 specifically includes: combining the resistivity ρ calculated in step S4 with a preset target resistivity ρ 标 A comparison is performed, and the calculated resistivity ρ matches the preset target resistivity ρ. 标 When the minimum value requirement is met, the position information of the crystal rod to be tested in the crystal pulling subsystem is obtained, thereby determining the effective length L of the crystal rod to be tested, so that a qualified crystal rod can be obtained simply by cutting the crystal rod to be tested according to the effective length L.

[0080] This application also discloses a crystal rod cutting system, the structure of which is shown in the attached figure. Figure 2 and attached Figure 3 As shown, it includes a weighing subsystem 1, a calculation subsystem 2, and a truncation subsystem 3.

[0081] Specifically, the weighing subsystem 1 is used to measure and weigh the raw materials in the single crystal furnace pot, thereby obtaining the amount of material T remaining in the pot during the crystal pulling process. The calculation subsystem 2 is signal-connected to the weighing subsystem 1 and is used to calculate the resistivity ρ at different positions of the crystal rod under test based on the amount of material T. The truncation subsystem 3 is used to truncate the crystal rod under test.

[0082] When the resistivity ρ calculated by calculation subsystem 2 meets the preset target resistivity ρ 标 When the minimum value requirement is met, the position information of the crystal rod to be tested is obtained through the crystal pulling subsystem 4 of the single crystal furnace, thereby determining the effective length L of the crystal rod to be tested. The cutting subsystem 3 can then cut the crystal rod to be tested according to the effective length L, thereby obtaining a qualified crystal rod.

[0083] More specifically, the calculation subsystem 2 includes a first calculation module 21 for calculating the first dopant concentration N1 using the weight of the polycrystalline silicon raw material W and the weight M of the master alloy according to formula (1); a second calculation module 22 for calculating the weight G of the test ingot using the remaining amount T according to formula (2); a third calculation module 23 for calculating the second dopant concentration N2 using the first dopant concentration N1 and the weight G of the test ingot according to formula (3); a first acquisition module 24 for obtaining the calculation formula (5) or (6) for the dopant concentration and resistivity of the test ingot; and a fourth calculation module 25 for calculating the resistivity ρ of the test ingot using the second dopant concentration N2 of the third calculation module 23 according to the relationship formula (5) or (6) of the first acquisition module 24.

[0084] The truncation subsystem 3 includes a transport device 31 for transporting the crystal rod to be tested, a length detection device 32 for visually scanning the crystal rod placed on the transport device 31 to measure its length, and a truncation device 33. In practical applications, when the resistivity ρ calculated by the calculation subsystem 2 meets the preset target resistivity ρ... 标 When the minimum value requirement is met, the positional relationship of the crystal rod to be tested is obtained through the crystal pulling system 4, thereby determining the effective length L of the crystal rod to be tested; when cutting, the length of the crystal rod to be tested is first measured by the length detection device 32 to determine the cutting position of the crystal rod to be tested, thereby obtaining a qualified crystal rod.

[0085] In some embodiments, the calculation subsystem 2 further includes a second acquisition module 26, which presets the target resistivity ρ in advance. 标 The requirement is that the resistivity ρ calculated by the fourth calculation module 25 meets the preset target resistivity ρ. 标 When the minimum value requirement is met, the second acquisition module 26 can acquire the position information of the crystal rod to be tested in the crystal pulling subsystem, so as to obtain the effective length L of the crystal rod to be tested and store it.

[0086] Therefore, in the actual production process, the test ingot and the effective length L can be numbered accordingly to achieve delayed truncation, which facilitates the installation and design of the entire system.

[0087] In some embodiments, the length detection device 32 includes a scanner and a scribing unit 321. The length is measured by the scanner, which is prior art and does not present any difficulty for those skilled in the art.

[0088] More specifically, the cutting device 33 includes a cutting unit 331 and a position sensor 332 for identifying the position of the scribe line.

[0089] The cut-off position of the crystal rod to be tested is determined by the effective length L and the scanner, and the scribing unit 321 marks the line. When the crystal rod to be tested moves to the cutting device 33, the position sensor 332 identifies the scribing mark on the crystal rod to be tested and controls the cutter unit 331 to cut the crystal rod to be tested.

[0090] As can be seen from the above description, the working principle and beneficial effects of the crystal rod cutting method and system provided in the embodiments of this application are as follows:

[0091] The remaining material T in the pot is measured by the weighing subsystem 1, and the resistivity ρ at different positions of the crystal rod under test is calculated based on the remaining material T, thus comparing it with the preset target resistivity ρ. 标 A comparison is performed, and when the target resistivity ρ is satisfied... 标 When the minimum value requirement is met, the position information of the crystal rod to be tested is obtained through the crystal pulling system 4, thereby obtaining the effective length L of the crystal rod to be tested, and the crystal rod is cut according to the effective length L to obtain a qualified crystal rod. This method only requires one cut to obtain a qualified crystal rod, thereby greatly improving work efficiency.

[0092] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for cutting a crystal rod, characterized in that, Includes the following steps: S1. Calculate the concentration of the first dopant based on the relationship between the weight of the polycrystalline silicon raw material and the weight of the master alloy; S2. Obtain the amount of material remaining in the pot and calculate the weight of the crystal rod to be tested based on the amount of material remaining; S3. Calculate the concentration of the second dopant at different positions on the crystal rod under test based on the relationship between the weight of the crystal rod under test and the calculated concentration of the first dopant. S4. Calculate the resistivity at different locations on the test ingot based on the relationship between the concentration of the second dopant and the resistivity. S5. Compare the calculated resistivity with the target resistivity. When the calculated resistivity meets the requirement of the minimum target resistivity, obtain the position information of the crystal rod to be tested, determine the effective length of the crystal rod to be tested, and cut it off to obtain a qualified crystal rod.

2. The method for cutting a crystal rod according to claim 1, characterized in that, The calculation of the first dopant concentration based on the relationship between the weight of the polycrystalline silicon raw material and the weight of the master alloy includes: Using formula ， Calculate the concentration of the first dopant; Where M is the weight of the master alloy; W represents the weight of the polycrystalline silicon raw material; N3 represents the impurity concentration of the master alloy; N1 is the concentration of the first dopant; K is the segregation coefficient of impurities in silicon.

3. The method for cutting a crystal rod according to claim 1, characterized in that, The calculation of the first dopant concentration based on the relationship between the weight of the polycrystalline silicon raw material and the weight of the master alloy includes: Using formula ， Calculate the concentration of the first dopant; Wherein, N1 is the concentration of the first dopant; M is the weight of the master alloy; W represents the weight of the polycrystalline silicon raw material.

4. The method for cutting a crystal rod according to claim 1, characterized in that, The calculation of the weight of the crystal rod to be tested based on the remaining material includes: Using formula ， Calculate the weight of the crystal rod to be tested; Where G is the weight of the crystal rod to be tested; M is the weight of the master alloy; W represents the weight of the polycrystalline silicon raw material; T represents the amount of remaining material in the pot.

5. The method for cutting a crystal rod according to claim 1, characterized in that, The calculation of the second dopant concentration at different locations on the test rod based on the relationship between the weight of the test rod and the calculated first dopant concentration includes: Using formula ， Calculate the concentration of the second dopant; Wherein, N2 is the concentration of the second dopant; N1 is the concentration of the first dopant; K is the segregation coefficient of impurities in silicon; g represents the ratio of the weight of the crystal rod to be tested to the total weight of the polycrystalline silicon raw material and the master alloy.

6. The method for cutting a crystal rod according to claim 1, characterized in that, The calculation of the resistivity at different locations of the test ingot based on the relationship between the second dopant concentration and resistivity includes: When the crystal rod to be tested is a P-type crystal rod, the formula is used. ， Calculate the resistivity of the crystal rod to be tested; When the crystal rod to be tested is an N-type crystal rod, the formula is used. ， Calculate the resistivity of the crystal rod to be tested; Where ρ is resistivity; N2 represents the concentration of the second dopant. ； A0=-3.0769, A1=2.2108, A2=-0.62272, A3=0.057501, B1=-0.68157, B2=0.19833, B3=-0.018376.

7. A crystal rod cutting system, signal-connected to the crystal pulling subsystem of a single crystal furnace, characterized in that, include: The weighing subsystem is used to measure the amount of material remaining in the pot; A calculation subsystem, connected to the weighing subsystem and the crystal pulling subsystem, is used to calculate the resistivity of the crystal rod to be tested based on the amount of residual material measured by the weighing subsystem. The truncation subsystem is connected to the calculation subsystem by signal, and can determine the effective length of the crystal rod under test based on the resistivity calculated by the calculation subsystem and the position information of the crystal rod under test in the crystal pulling subsystem, and truncate the crystal rod under test to obtain a qualified crystal rod; The computing subsystem includes: The first calculation module is used to calculate the first dopant concentration based on the weight of the polysilicon raw material and the weight of the master alloy. The second calculation module is connected to the weighing subsystem and is used to calculate the weight of the crystal rod to be tested based on the amount of remaining material. The third calculation module is used to calculate the second dopant concentration based on the first dopant concentration and the weight of the crystal rod to be tested; The first acquisition module is used to acquire the calculation formulas for the dopant concentration and resistivity of the crystal rod under test; The fourth calculation module is used to calculate the resistivity of the test rod according to the calculation formula of the first acquisition module and the second dopant concentration of the third calculation module.

8. The crystal rod cutting system according to claim 7, characterized in that, The computing subsystem also includes a second acquisition module; The second acquisition module is used to acquire the position information of the crystal rod under test in the crystal pulling subsystem; When the resistivity obtained by the fourth calculation module meets the minimum value requirement of the preset target resistivity, the second acquisition module acquires the position information of the crystal rod to be tested in the crystal pulling subsystem, so as to obtain the effective length of the crystal rod to be tested and store it.

9. The crystal rod cutting system according to claim 7 or 8, characterized in that, The truncation subsystem includes: A transfer device is used to transfer the crystal rod to be tested; A length detection device is used to perform an external scan on the crystal rod to be tested placed on the transfer device to measure its length and determine the cut-off position of the crystal rod to be tested based on the effective length of the crystal rod to be tested. The cutting device is signal-connected to the length detection device and can cut the crystal rod to be tested according to the cutting position determined by the length detection device.

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