A wafer rod automatic cutting method

Abstract

The present invention provides a method for automatically cutting wafer ingots, comprising the following steps: scanning the wafer ingot's appearance to measure its length and determine the effective length of the wafer ingot; a marking step for determining the marking positions of the corresponding segments based on the effective length of the wafer ingot; a cutting step for sequentially cutting the wafer ingot into segments at the marking positions; and a determination of the appropriate marking length within the effective length during the marking step. The cutting method of the present invention can automatically measure the length of the wafer ingot, automatically complete marking and centering, determine the cutting position based on the preferred short ingot length, and simultaneously affix a label to the end face of the corresponding short ingot to be cut. It has a high degree of automation, high precision, and high production efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon single crystal rod truncation, and in particular relates to a method for automatically judging, cutting and truncation of a wafer rod. Background Art

[0002] Existing cutting and slicing equipment used in Czochralski single crystal production is semi-manual and semi-automatic. This means that after manual marking and quality inspection, the wafers are manually transported to the cutting machine, where they are then manually operated for cutting and slicing. However, due to errors in manual measurement, calculation, marking, and alignment, the yield of the resulting short ingots is low. Furthermore, production is highly unstable, resulting in significant waste of labor, poor product consistency, and low productivity. With current manual operation, it takes 4-5 hours to cut a single wafer ingot, a significant time constraint that severely hinders mass production. Summary of the Invention

[0003] The present invention provides an automatic wafer bar cutting method, which is particularly suitable for wafer bar cutting and slicing, and solves the technical problems of low automation, poor product consistency and low production efficiency in the prior art.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for automatically cutting a wafer bar comprises the following steps:

[0006] A measurement process of performing an appearance scan on a wafer bar to measure its length and determine the effective length of the wafer bar;

[0007] A scribing process for determining scribing positions of corresponding segments based on the effective length of the wafer bar;

[0008] a cutting process of sequentially cutting the wafer rod into sections at the scribe lines;

[0009] The scribing step includes determining a suitable scribing length from the effective lengths.

[0010] Furthermore, the measuring process specifically includes:

[0011] Collecting the external shape data of the wafer bar and determining whether the wafer bar includes a head section and / or a tail section;

[0012] If so, record the head segment and / or the tail segment, and the length of the equal-diameter segment is the effective length;

[0013] If not, the wafer rod length is the effective length.

[0014] Furthermore, when collecting the wafer bar appearance data, it also includes:

[0015] Performing a visual inspection scan on the wafer rod to determine whether there is any quality abnormal section within the effective length range;

[0016] When the abnormal segment appears, its position is recorded and its length is measured, and the abnormal segment is marked separately in the marking process.

[0017] Furthermore, the abnormal section includes a diameter abnormal section where the diameter of the wafer rod in the effective length is smaller than the standard size and / or a twin abnormal section where any crystal line of the wafer rod is broken.

[0018] Furthermore, the scribing process specifically includes:

[0019] determining whether the valid length contains the abnormal segment;

[0020] If it does not contain the abnormal segment:

[0021] Controlling the effective length to be compared with a plurality of pre-sorted and set different standard length benchmarks;

[0022] Determine which reference length the effective length is a multiple of, select the reference, and calculate how many reference lengths are contained in the effective length;

[0023] Then, lines are drawn at positions that are integer multiples of the reference on the effective length.

[0024] Furthermore, if the abnormal segment is included:

[0025] Controlling then comparing the lengths of all remaining segments in the effective length that do not contain the abnormal segment with the sorted benchmark respectively;

[0026] sequentially determining which reference length all the remaining lengths are multiples of, selecting the corresponding reference, and calculating how many reference lengths are contained in the remaining lengths;

[0027] Then, lines are drawn at positions that are integer multiples of the reference on all the remaining segments, and lines are also drawn on the abnormal segments.

[0028] Furthermore, when the effective length is less than the shortest reference length, the marking is stopped.

[0029] Furthermore, for the wafer rod including the head section and / or the tail section, scribing within the effective length also includes scribing the head section and / or the tail section;

[0030] For the wafer bar that does not include the head section or the tail section, only the effective length is scribed.

[0031] Furthermore, the truncation process specifically includes:

[0032] fixing the wafer rod;

[0033] Based on the tangent line position, the wafer rod is cut into sections in sequence.

[0034] Furthermore, it also includes the marking process, which specifically includes:

[0035] Based on the specifications of the wafer rod and the length of the short rod after truncating, an identification sticker is automatically generated and affixed to the end face of each short rod;

[0036] The automatic generation of the identification label and the cutting and truncation in the truncation process are performed simultaneously.

[0037] The automated cutting method designed in this invention automatically measures wafer ingot length, completes scribing and centering, and determines cuts based on the desired short ingot length. It also places a label on the end face of the corresponding cut short ingot. This method offers a high degree of automation, precision, and production efficiency, reducing processing time from the current manual process of 4-5 hours to 2-3 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of a method for automatically cutting a wafer bar according to an embodiment of the present invention;

[0039] Figure 2 1 is a schematic structural diagram of a wafer bar after scribing according to the first embodiment of the present invention;

[0040] Figure 3 Schematic diagram of the structure of the wafer bar after scribing according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] This embodiment proposes a method for automatically cutting a wafer bar. Figure 1 As shown,

[0043] S1. Placement process

[0044] The wafer ingot is placed horizontally on a roller conveyor equipped with several rolling wheels, which drive the wafer ingot forward. The wafer ingot can be any crystal ingot with a head and / or tail section, or a truncated crystal ingot of equal diameter. Preferably, the head section, or the end closest to the head section, enters the roller conveyor first and moves toward the cutting blade.

[0045] S2. Measurement process

[0046] This process is to scan the appearance of the wafer rod to measure its length and determine the effective length of the wafer rod. Specifically includes:

[0047] The wafer rod is controlled to move along the longitudinal axis of the roller table and is simultaneously aligned to ensure the accuracy of subsequent scribing and the flatness of the end surface of the short rod after subsequent truncation. The alignment of the wafer rod and the roller table axis is performed automatically.

[0048] The wafer ingot's external shape data is then collected using a mapping instrument, primarily to determine its structural shape and whether it is a whole wafer ingot with a tapered head section and / or a boss-shaped tail section, or a crystal ingot with a constant diameter structure without any head or tail sections. The mapping instrument can be used to obtain the wafer ingot's head section length, constant diameter section length, tail section length, and constant diameter section diameter, as well as its external shape and structure. The effective length is the length of the constant diameter section of the wafer ingot. That is, for a whole wafer ingot with a head section and / or tail section, the length of the constant diameter section is the effective length of the wafer ingot. For a crystal ingot with a constant diameter structure without any head or tail section, the effective length is the length of the wafer ingot itself.

[0049] The surveying instrument is a three-dimensional surveying and mapping device. It is a surveying and mapping device with a commonly used external structure. While obtaining the external data of the wafer rod, it can also perform an annular appearance quality scanning inspection on the outer wall surface of the wafer rod to check and determine whether there are abnormal sections with abnormal diameter and / or abnormal twins on the equal-diameter sections of the wafer rod, that is, to determine whether there are abnormal sections with abnormal diameter and / or abnormal twins within the effective length range.

[0050] A diameter anomaly occurs when the tester detects that the actual diameter of a uniform diameter segment is smaller than the set standard diameter, falling outside the standard diameter range. This indicates a quality issue with the uniform diameter of the wafer ingot, making subsequent trimming and squaring impossible, and thus, unqualified silicon wafers unavailable. A twinning anomaly occurs when any of the crystal lines on the outer wall of the wafer ingot are broken, absent, or unclear. This twinning problem is caused by dislocations and can lead to dark patches in subsequently produced solar cells and leakage problems in the resulting solar modules. Therefore, both the abnormally reduced diameter segment and the abnormally twinned segment must be cut and removed.

[0051] When any abnormal segment appears on the wafer rod, its starting and ending positions are recorded and the position information of the abnormal segment is transmitted to the central control program, and then transmitted to the scribing process through the central control program.

[0052] During this process, it is first determined whether the wafer rod has a head section and / or a tail section:

[0053] If so, the length of the equal-diameter segment after excluding the head segment and / or tail segment is the effective length.

[0054] If there is no head section or tail section, the length of the entire wafer rod is its effective length.

[0055] Then check whether there are any abnormal segments in the valid length:

[0056] If there is, its starting position is determined and its length is measured so that the abnormal segment can be marked out separately during subsequent marking, and the information is then passed to the central control program for summary.

[0057] If not, no need to record and proceed to the next step.

[0058] S3, marking process

[0059] The purpose of this process is to select the appropriate scribing length based on the effective length of the wafer bar and determine the scribing position of the corresponding segment. Specifically, it includes:

[0060] Several different standard lengths are preset as benchmarks and sorted according to the production scheduling priority. In actual production, based on the length of the square bars processed by the slicer, several standard processing lengths are set, such as 620mm, 650mm, 700mm, 800mm, and 1000mm. At the same time, this group of processing lengths is sorted according to the production urgency level, with important and urgent benchmark lengths being given priority, followed by non-urgent and important benchmark lengths.

[0061] S31. Compare and judge the effective length excluding abnormal segments with the sorted benchmark.

[0062] When the effective length includes an integer multiple of the reference length, a line is drawn at the position of the integer multiple of the reference.

[0063] When the effective length is a multiple of the first reference length, the multiple of the reference length is calculated and the position and length value of the line to be drawn are determined.

[0064] When the remaining length in the effective length is less than the first reference length value, the remaining length is compared with the second reference length value to determine whether the remaining length is a multiple of the second reference length value.

[0065] If so, calculate the multiple of the second reference length and determine the position and length of the line to be drawn.

[0066] If not, continue to compare the remaining segment length with the multiple of the third reference length to determine whether the remaining segment length is a multiple of the third reference length value.

[0067] When the length of the remaining segment is less than the shortest reference length, no comparison or judgment is performed and the line drawing ends.

[0068] S32. Compare and judge the effective length of the abnormal segment with the sorted benchmark.

[0069] First determine the length and location of the abnormal segment and record it;

[0070] The remaining lengths of all valid lengths excluding abnormal segments are then compared with the sorted benchmarks in sequence, and the rod length positions and lengths that meet the benchmarks are selected and recorded. The step of comparing the remaining lengths excluding abnormal segments with the sorted benchmarks is the same as in S31 and is omitted here.

[0071] Specifically, due to the presence of outliers, when comparing the effective length to the first benchmark length, all remaining segments, excluding the outliers, need to be compared with the first benchmark length. If any of the remaining segments exceeds the first benchmark length, the number of multiples of the first benchmark in the remaining segment can be calculated, and a corresponding number of lines are drawn accordingly. If all remaining segments are less than the first benchmark length, the remaining segment is compared with the second benchmark length. This process continues until a segment is found that is a multiple of the standard benchmark length. Based on the comparison and calculation records, the effective length of the wafer ingot is then segmented and marked.

[0072] When the lengths of the remaining segments of the effective length are all less than the shortest reference length, there is no need to mark the remaining segments, and only the abnormal segments need to be marked on the effective length.

[0073] Furthermore, the method further includes marking the head length and tail length of the wafer rod.

[0074] S33. When the total length of the effective length is directly less than the shortest reference length value, there is no need to draw a line.

[0075] During the scribing process, for a wafer bar having a head section and / or a tail section, the scribing process also needs to consider the connection between the head section and the effective length, and the connection between the effective length and the tail section.

[0076] S4, cutting process

[0077] The wafer bar is cut into sections at the scribe line positions calculated in step S3.

[0078] First, control the wafer rod to pass through the cutter and make the tangent position directly below the cutter, then clamp the wafer rod and fix it on the roller.

[0079] The wire cutter's linear speed and descent speed are preset in advance to 13-15 m / s and 0.5-1 mm / s, respectively. A waiting time of 8-12 seconds is also preset after the cutter has descended to ensure it cuts through the wafer ingot. The rated speed of the motor controlling the cutter tooling is also determined. The cutting process is then executed until all segments are complete.

[0080] If the wafer rod has a head length, the head length is cut off first, and then cut off in sequence according to the scribe line position;

[0081] If the wafer rod contains a tail length, the tail length is cut off in the last section of the effective length.

[0082] S5, marking process

[0083] This process is mainly based on the specifications of the wafer rods and the length of the truncated short rods. The identification stickers are automatically generated on the marking machine and pasted on the end face of each short rod to obtain the corresponding technical parameters of each short rod, forming a recognizable smart mark to improve production efficiency and save production time for subsequent production scheduling.

[0084] The automatic generation of identification labels on the marking machine and the cutting and truncation in the truncation process are carried out simultaneously.

[0085] Example 1:

[0086] A whole wafer rod with a diameter of 300mm and including a head section and a tail section.

[0087] S1. Placement process

[0088] The wafer rods are placed horizontally on the roller conveyor, with their head sections entering the roller conveyor first.

[0089] S2. Measurement process

[0090] The measurement shows that the length of the head section L1 of the wafer rod is 315mm, the length of the equal diameter section L2 is 3000mm, the length of the tail section L3 is 120mm, and there are no abnormal problems in the entire wafer. Therefore, the effective length of the wafer rod is 3000mm.

[0091] S3, marking process

[0092] The sorted benchmark lengths H are: 700mm, 800mm, 1000mm, 650mm and 620mm, so the first benchmark H1 is 700mm, the second benchmark H2 is 800mm, the third benchmark H3 is 1000mm, the fourth benchmark H4 is 650mm, and the fifth benchmark H5 is 620mm.

[0093] Then the comparison between the effective length L2 of 3000 mm and the length of the first benchmark H1 of 700 mm is performed;

[0094] Since the effective length of 3000mm is greater than the length of the first datum H1 of 700mm and is a multiple of the first datum H1, that is, the effective length includes 4 sections of the length of the first datum H1 of 700mm, 4 lines are drawn in sequence.

[0095] The remaining 200 mm is less than the minimum reference H5 length of 620 mm, so marking cannot be performed.

[0096] Accordingly, for the scribe line position of the entire wafer bar, the structure is as follows Figure 2 As shown; including 1 connection between the head segment and the equal diameter segment, 4 lines of the equal crystal segment, and 1 connection between the tail segment and the equal diameter segment, a total of 6 lines.

[0097] S4, cutting process

[0098] The wafer bar is cut into sections at the scribe line positions calculated in step S3.

[0099] First, control the wafer rod to pass through the cutter and make the tangent position directly below the cutter, then clamp the wafer rod and fix it on the roller.

[0100] The linear speed and descent speed of the diamond wire cutter are preset in advance to 13m / s and 1mm / s respectively; the waiting time after the cutter is lowered is also preset to 12s to ensure that the cutter cuts through the wafer rod; at the same time, the rated speed of the motor of the cutter tooling is controlled to 50r / min.

[0101] Execute the cutting process until all segments are completed.

[0102] S5, marking process

[0103] Based on the specifications of the wafer rods and the length of each short rod after truncation, an identification sticker is automatically generated on the marking machine and affixed to the end face of each short rod after truncation.

[0104] In this embodiment, a comparison of the time required for this method and the time required for conventional manual operation on the same wafer ingot is shown in Table 1. It can be seen that the time required for this method is 3 hours, far less than the 5 hours required by the conventional manual operation. Furthermore, the scribing yield of this embodiment is 99.5%, while the yield of the conventional manual operation is only 96.8%. Therefore, the truncation method in this embodiment saves nearly 2 hours of work time and improves the yield by nearly 2.7%.

[0105] Table 1 Comparison of the method and the existing manual operation for wafer rods with a diameter of 300mm

[0106]

[0107] Example 2:

[0108] Wafer rod with a diameter of 280mm, excluding the head and tail sections.

[0109] S1. Placement process

[0110] The wafer rod is placed horizontally on the roller conveyor, with the end closest to the head entering the roller conveyor first.

[0111] S2. Measurement process

[0112] The wafer rod is mapped to a uniform diameter section, which is a wafer rod with a length L2 of 2000 mm. Figure 3 As shown, the effective length of the wafer rod is 2000mm. However, there is a 200mm long twinning abnormal section L0 on the wafer rod. The abnormal section L0 is 680mm away from the end close to the head T1 and 1120mm away from the end far from the head T2.

[0113] S3, marking process

[0114] The sorted benchmark lengths H are still: 700mm, 800mm, 1000mm, 650mm and 620mm, so the first benchmark H1 is 700mm, the second benchmark H2 is 800mm, the third benchmark H3 is 1000mm, the fourth benchmark H4 is 650mm, and the fifth benchmark H5 is 620mm.

[0115] First, compare the length of T1, 680 mm, with the length of the first benchmark, H1, 700 mm;

[0116] Since the length of T1 (680 mm) is less than the length of H1 (700 mm), a comparison between T1 and H2 is performed;

[0117] Since the length of T1 (680 mm) is less than the length of H2 (800 mm), a comparison between T1 and H3 is performed;

[0118] Since the length of T1 (680 mm) is less than the length of H3 (1000 mm), a comparison between T1 and H4 is performed;

[0119] Since the length of T1 (680 mm) is greater than the length of H4 (650 mm), and T1 is 1 times the length of H4, draw a line on the T1 segment.

[0120] The remaining length of T1 after removing H4 is 30 mm, which is less than the length of the minimum reference H5 of 620 mm, so marking cannot be performed.

[0121] And draw lines at both ends of the abnormal section L0 on the effective length L2.

[0122] Then compare the length of T2 (1120 mm) with the length of the first benchmark H1 (700 mm).

[0123] Since the length of T2 (1120 mm) is greater than the length of H1 (700 mm), and T2 is twice the length of H2, draw a line on T2.

[0124] The remaining length of T2 after removing H1 is 420 mm, which is less than the length of the minimum reference H5 of 620 mm, so marking cannot be performed.

[0125] At this point, all the line calculations for the wafer bar are completed. Correspondingly, for the line positions of the entire wafer bar, the structure is as follows Figure 3 As shown; including 1 in T1, 1 at the connection between T1 and L0, 1 at the connection between L0 and T2, and 1 in T2, a total of 4.

[0126] S4, cutting process

[0127] The wafer bar is cut into sections at the scribe line positions calculated in step S3.

[0128] First, control the wafer rod to pass through the cutter and make the tangent position directly below the cutter, then clamp the wafer rod and fix it on the roller.

[0129] The linear speed and descent speed of the diamond wire cutter are preset in advance to 10m / s and 0.8mm / s respectively; the waiting time after the cutter is lowered is preset to 10s to ensure that the cutter cuts through the wafer rod; at the same time, the rated speed of the motor of the cutter tooling is controlled to 50r / min.

[0130] Execute the cutting process until all segments are completed.

[0131] S5, marking process

[0132] Based on the specifications of the wafer rods and the length of each short rod after truncation, an identification sticker is automatically generated on the marking machine and affixed to the end face of each short rod after truncation.

[0133] In this embodiment, a comparison of the time required for this method with the time required for conventional manual operation on the same wafer ingot is shown in Table 2. It can be seen that the time required for this method is 2 hours, far less than the 4.1 hours required for conventional manual operation. Furthermore, the scribing yield of this embodiment is 99.8%, while the yield of conventional manual operation is only 97.2%. Therefore, the truncation method in this embodiment saves nearly 1.8 hours of work and improves the yield by nearly 2.6%.

[0134] Table 2 Comparison of the method and the existing manual operation for wafer rods with a diameter of 280 mm

[0135]

[0136] The automatic cutting method designed by the present invention can automatically measure the length of the wafer rod, automatically complete the marking and movement centering, judge the cutting according to the priority short rod length, and at the same time post a mark on the end face of the corresponding cut short rod. The degree of automation is high, the processing time is reduced from the existing 4-5 hours to the existing 2-3 hours, the yield rate is increased by about 2.5% or more, and the production efficiency is high.

[0137] The above embodiments of the present invention are described in detail. The contents described are only preferred embodiments of the present invention and should not be considered to limit the scope 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 automatically cutting a wafer rod, characterized in that the steps include: A measurement process of performing an appearance scan on a wafer ingot to measure its length and determine the effective length of the wafer ingot; the measurement process includes: collecting the external shape data of the wafer ingot; while collecting the external shape data of the wafer ingot, performing an appearance inspection scan on the wafer ingot to determine whether there is any quality abnormal section within the effective length range; if the abnormal section is present, recording its location and measuring its length, and marking the abnormal section separately in a marking process; A scribing process of determining scribing positions of corresponding segments based on the effective length of the wafer bar; a cutting process of sequentially cutting the wafer rod into sections at the scribe lines; In the marking process, a judgment is provided for selecting an appropriate marking length from the effective length; The scribing process specifically includes: determining whether the valid length contains the abnormal segment; If it does not contain the abnormal segment: Controlling the effective length to be compared with a plurality of different reference lengths set in advance; Determining which of the reference lengths the effective length is a multiple of; Select the reference length and calculate how many of the reference lengths are included in the effective length; Then, marking the effective length at positions that are integer multiples of the reference length; If it contains the abnormal segment: Then, the lengths of all remaining segments in the effective length that do not contain the abnormal segment are controlled to be compared with the sorted reference lengths respectively; sequentially determining which of the reference lengths all the remaining lengths are multiples of; Select the corresponding reference length and calculate how many reference lengths are contained in the remaining length; Then, lines are drawn at positions that are integer multiples of the reference length on all the remaining segments, and lines are also drawn on the abnormal segments.

2. The method for automatically cutting a wafer rod according to claim 1, wherein: The measuring process specifically includes: determining whether the wafer bar includes a head section and / or a tail section; If so, record the head segment and / or the tail segment, and the length of the equal-diameter segment is the effective length; If not, the wafer rod length is the effective length.

3. The method for automatically cutting a wafer rod according to claim 1, wherein: The abnormal section includes a diameter abnormal section where the diameter of the wafer rod in the effective length is smaller than the standard size and / or a twin abnormal section where any crystal line of the wafer rod is broken.

4. The method for automatically cutting a wafer rod according to claim 1, wherein: When the effective length is less than the shortest reference length, the marking is stopped.

5. The method for automatically cutting a wafer bar according to claim 2, wherein: For the wafer rod including the head section and / or the tail section, scribing within the effective length also includes scribing the head section and / or the tail section; For the wafer bar that does not include the head section or the tail section, only the effective length is scribed.

6. The method for automatically cutting a wafer bar according to claim 1, wherein: The truncation process specifically includes: fixing the wafer rod; Based on the tangent line position, the wafer rod is cut into sections in sequence.

7. The method for automatically cutting a wafer bar according to claim 1, wherein: It also includes the marking process, including: Based on the specifications of the wafer rod and the length of the short rod after truncating, an identification sticker is automatically generated and affixed to the end face of each short rod; The automatic generation of the identification label and the cutting and truncation in the truncation process are performed simultaneously.

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