An automatic control suction method in a czochralski single crystal process

Abstract

The application provides an automatic control suction method in a Czochralski single crystal process, and the steps include: obtaining the lifetime value and resistivity of a single crystal silicon rod that has been drawn; judging the lifetime value of the single crystal silicon rod that has been drawn and the ratio of the lifetime value to the resistivity; if the lifetime value and the ratio of the lifetime value to the resistivity are both greater than the corresponding set values, the drawing process is continued; if the lifetime value and / or the ratio of the lifetime value to the resistivity is not greater than the corresponding set value, the segment suction process is executed. The automatic control suction method can accurately judge the suction condition, does not need personnel intervention operation, maximally reduces human error, improves work efficiency, shortens the operation time from the existing 3-4 hours of two people to 1-2 hours of one person, and can also ensure the completeness of the suction, so that the suction tool can be repeatedly used for many times and the production progress is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar photovoltaic single crystal drawing, and particularly relates to an automatic control material suction method in a Czochralski single crystal process. BACKGROUND

[0002] In the existing single crystal drawing, in order to reduce cost and increase efficiency, a segment taking and re-feeding mode is adopted for drawing. However, the multiple segment taking and re-feeding can cause the aggregation of metal impurities in the remaining material in the crucible, greatly reduce the minority carrier lifetime of the next single crystal, and affect the quality and effective yield of the single crystal. Moreover, once the minority carrier lifetime is abnormal, the furnace must be directly stopped, thereby increasing the cost of starting the furnace and causing a loss. The material suction at the bottom of the crucible can timely end the generation of the single crystal silicon rod failure rate, but the current industry mainly adopts manual operation for the material suction operation, which is not only low in efficiency and long in material suction time, but also causes poor material suction effect due to different operation proficiency of personnel. The current manual material suction consumes 3-4 hours of time of two persons at one time, which seriously affects the production progress and production efficiency. SUMMARY

[0003] The application provides an automatic control material suction method in a Czochralski single crystal process, and solves the technical problems of low efficiency and unstable material suction quality of the current manual operation material suction tool.

[0004] To solve the above technical problems, the technical scheme adopted by the application is as follows:

[0005] An automatic control material suction method in a Czochralski single crystal process, comprising the following steps:

[0006] obtaining the lifetime value and the resistivity of a single crystal silicon rod that has been drawn;

[0007] judging the lifetime value of the single crystal silicon rod that has been drawn and the ratio of the lifetime value to the resistivity,

[0008] if the lifetime value and the ratio of the lifetime value to the resistivity are both greater than the corresponding set values, a re-feeding drawing program is continuously executed;

[0009] if the lifetime value or / and the ratio of the lifetime value to the resistivity is not greater than the corresponding set value, a segment taking and material suction program is executed.

[0010] Further, the lifetime value and the resistivity are both test values of the same position of the head of the single crystal silicon rod that has been drawn.

[0011] Further, the set value of the lifetime value is 120-125 us.

[0012] Further, the set value of the ratio of the lifetime value to the resistivity is 150-250.

[0013] Further, the taking section and sucking material procedure specifically includes:

[0014] judging whether the remaining material in the quartz crucible is within a safe range;

[0015] if yes, continue to draw a single crystal silicon rod until the weight of the remaining material in the quartz crucible is not more than 25 kg;

[0016] if no, stop drawing a single crystal silicon rod and start sucking material process.

[0017] Further, before executing the sucking material process, it includes:

[0018] after taking out the last single crystal silicon rod being drawn away from the molten silicon surface,

[0019] controlling the crucible position of the quartz crucible to drop to a set sucking material position; and

[0020] increasing the power of the main heater and the power of the bottom heater;

[0021] when the rotation speed of the quartz crucible drops to 1-2 r / min,

[0022] automatically performing a cooling process on the single crystal silicon rod being drawn.

[0023] Further, the increasing the power of the main heater and the power of the bottom heater includes:

[0024] the power of the main heater is 10-15 kw higher than the main heating power during crystal pulling, and

[0025] the power of the bottom heater is 15-20 kw higher than the main heating power during crystal pulling;

[0026] the power of the main heater and the power of the bottom heater during sucking material are fixed values until the end of sucking material.

[0027] Further, the sucking material process includes the following steps:

[0028] purification of the sub-chamber;

[0029] gradual preheating of the sucking material tool for sucking material;

[0030] sucking the remaining material at the bottom of the crucible.

[0031] Further, the step of gradually preheating the sucking material workpiece includes:

[0032] presetting at least two times of static preheating of the sucking material workpiece, and with the increase of the sinking depth of the sucking material workpiece, the time of each static preheating is extended by 4-10 min longer than the previous one;

[0033] Controlling the suction tool to descend and determining whether the suction tool is in contact with the liquid surface;

[0034] When the contact voltage alarm of the suction tool is received, the suction tool is adjusted to ascend 1-5 mm, and then is again placed for a certain time of preheating;

[0035] The suction tool is again controlled to descend to the liquid surface, and whether the suction tool is in contact with the liquid surface is determined;

[0036] When the contact voltage alarm of the suction tool is received, the rotation of the quartz crucible is adjusted to 1 r / min, and the preheating is completed.

[0037] Further, before the sub-chamber purification, it further includes determining whether the suction tool is stable, and the steps include:

[0038] First, it is identified and determined whether the suction tool is present;

[0039] Then, it is determined whether the suction tool is shaking;

[0040] If yes, an alarm is prompted to switch to manual stable control;

[0041] If not, the sub-chamber purification program is executed.

[0042] Further, the sub-chamber purification includes:

[0043] The suction tool is controlled to ascend to a minimum identification position;

[0044] The sub-chamber is isolated;

[0045] Then, the isolation valve on the sub-chamber is opened, and the suction tool is controlled to enter the main chamber.

[0046] Further, the remaining material in the suction crucible bottom includes:

[0047] When the contact voltage alarm of the suction tool is received, the suction tool is controlled to descend to 20-45 mm in the liquid surface;

[0048] The quartz crucible stops rotating, and the suction tool is placed;

[0049] The pressure control program is exited, and the sub-chamber is rapidly pressurized to a standard suction pressure value to start suction;

[0050] When the weight of the suction tool after suction is greater than the weight before suction and is stable, the suction is completed.

[0051] Further, the remaining material in the suction crucible bottom further includes cooling the suction tool after suction, and the steps include:

[0052] Start the quartz crucible to rotate at a low speed;

[0053] When the material suction tool loaded with remaining material is lifted into the water cooling jacket, it is statically cooled for a period of time;

[0054] When lifted into the sub-chamber and to the lowest point of the identification position, it is statically cooled for a period of time, and the cooling time is longer than that in the water cooling jacket;

[0055] Start the pressure control program;

[0056] Open the sub-chamber and take out the material suction tool.

[0057] The automatic control material suction method in the direct pulling single crystal process designed by the application can accurately judge the material suction condition, does not need personnel intervention operation, maximally reduces human error, improves work efficiency, shortens the operation time from the existing 3-4 hours of two persons to 1-2 hours of one person, and can also guarantee the completeness of the material suction, repeatedly uses the material suction tool, and improves the production progress. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 is a flow chart of the automatic control material suction method in the direct pulling single crystal process of an embodiment of the application. DETAILED DESCRIPTION

[0059] The application will be described in detail below in combination with the drawings and specific embodiments.

[0060] The embodiment proposes an automatic control material suction method in a direct pulling single crystal process, as shown in Figure 1 The steps include:

[0061] S1, judge whether to take a section of material suction.

[0062] S11, obtain the lifetime value and resistivity of the single crystal silicon rod that has been pulled, and continue to operate the single crystal silicon rod that is being pulled.

[0063] After each single crystal silicon rod is pulled, its minority carrier lifetime value and resistivity need to be detected, and the minority carrier lifetime value and resistivity value of the head of the silicon rod are the maximum values in the whole single crystal, so when selecting and judging, the lifetime value and resistivity of the single crystal silicon rod are selected as the lifetime value and resistivity close to the head end surface, and the lifetime value and resistivity are both test values at the same position.

[0064] The existing determination method considers the lifetime value or / and the resistivity value, that is, only the lifetime value is used as the only determination standard, or only the resistivity is used as the only determination standard, or the lifetime value and the resistivity are used together as the determination standard. If only the lifetime value is considered, if the low lifetime value is caused by the low resistivity, instead of the low lifetime value caused by the metal impurities, it will be mistakenly thought that the parameter is problematic, the product is downgraded, and loss is caused. If only the resistivity is used as the only determination condition, although the lifetime value is generally proportional to the resistivity, for the low lifetime value caused by the metal impurities, the resistivity does not change due to the stability of the dopant, that is, the resistivity is qualified, for this kind of situation, if only the qualified resistivity is determined, it is thought that the wafer rod quality is qualified; this will cause the wafer rod quality to be misjudged, resulting in waste products entering the good products, and affecting the yield. For the above two situations, if the wafer rod under the two conditions is not qualified according to the lifetime value and the resistivity, greater loss will be caused.

[0065] Therefore, the lifetime value and the ratio of the lifetime value to the resistivity are selected to be used for judgment, which not only prevents the probability of misjudging the product to be downgraded, but also avoids the possibility of judging the waste product to be a good product. Moreover, the consistency of the product parameters of the wafer rod and the actual product quality can be more accurately judged. For the selection of the lifetime value and the ratio of the lifetime value to the resistivity close to the head end surface, the lifetime value and the resistivity of the head are the optimal technical parameters of the whole single crystal, once the technical parameters of the head position do not meet the requirements, the lifetime value and the resistivity of the whole single crystal silicon rod are definitely not qualified, that is, the technical parameters of the head are the judgment reference of the whole single crystal. When testing, the lifetime value is the test value of the center position of the head end surface of the silicon rod, and the resistivity is the average value of the multi-point test value.

[0066] S12, judging whether the lifetime value of the single crystal silicon rod and the ratio of the lifetime value to the resistivity are qualified.

[0067] After obtaining the measured lifetime value and the resistivity of the single crystal silicon rod, the data is manually input into the program, and the system automatically stores and identifies and screens out the preferred and more concentrated lifetime values of all the silicon rods of this size.

[0068] The system calculates the lifetime value of the single crystal silicon rod and the ratio of the lifetime value to the resistivity, judges the lifetime value and the ratio of the lifetime value to the resistivity of the single crystal silicon rod,

[0069] If the lifetime value and the ratio of the lifetime value to the resistivity are both greater than the corresponding set value, the re-drawing program is continued to be executed;

[0070] If the lifetime value and / or the ratio of the lifetime value to the resistivity are not greater than the corresponding set value, that is, for the lifetime value and the ratio of the lifetime value to the resistivity, as long as one of them is not greater than the corresponding set value, the segment suction program is executed.

[0071] Wherein, the setting value of the lifetime value is 120-125us; the setting value of the ratio of the lifetime value and the resistivity is 150-250.

[0072] If any result is greater than the setting value, it indicates that the quality of the single crystal silicon rod is qualified, and the re-feeding and drawing process is continued, i.e. the single crystal silicon rod being drawn is completed, and after the completion of the drawing, the re-feeding is performed.

[0073] The lifetime value or the ratio of the lifetime value and the resistivity of each single crystal silicon rod drawn is judged until the result is less than the setting value, and then the segment suction process is performed.

[0074] S2, segment suction process.

[0075] S21, taking out the single crystal silicon rod being drawn.

[0076] After the last single crystal silicon rod being drawn is taken out to be away from the surface of the molten silicon, the position of the quartz crucible is controlled to be lowered to the setting suction position, in this embodiment, the position of the quartz crucible is lowered to a height of 280mm from the zero position of the quartz crucible, wherein the zero position of the quartz crucible is the position where the upper edge surface of the quartz crucible is flush with the upper edge surface of the main heater.

[0077] At the same time, the power of the main heater and the power of the bottom heater are increased, the power of the main heater is 10-15kw higher than that during the crystal pulling, and the power of the bottom heater is 15-20kw higher than that during the crystal pulling, at this time, the power of the main heater and the power of the bottom heater are fixed values until the end of the suction.

[0078] When the rotating speed of the quartz crucible is lowered to 1-2r / min, the cooling process is automatically performed on the single crystal silicon rod being drawn, i.e. during the lifting of the single crystal silicon rod, it is slowly lifted to be away from the main chamber to the auxiliary chamber, and it is allowed to be stationary in the main chamber and the auxiliary chamber for several minutes to complete the cooling of the single crystal silicon rod.

[0079] When the single crystal silicon rod enters the auxiliary chamber, the isolation valve of the auxiliary chamber is closed, and the auxiliary chamber is controlled to be opened, and the single crystal silicon rod is placed in the crystal taking barrel for cooling.

[0080] S22, judging whether the weight of the remaining material in the quartz crucible is within the safe range.

[0081] When the segment suction is performed, it is needed to judge in advance whether the remaining material in the quartz crucible is greater than 25kg, if yes, the remaining material in the quartz crucible is greater than 25kg, the drawing of the single crystal silicon rod is continued until the remaining material is less than or equal to 25kg.

[0082] If not, the drawing of the single crystal silicon rod is stopped, and the next suction process is performed.

[0083] S23, suction process.

[0084] S231, installation and stabilization of the suction tool.

[0085] Manually dismount the seed crystal chuck tool installed on the heavy hammer, and then manually install the suction tool.

[0086] After the suction tool is installed, tighten the sub-chamber.

[0087] Judge whether the suction tool is successfully installed, specifically, automatically raise the suction tool to a minimum height position that can be identified by the remote infrared sensor installed on the sub-chamber and the main chamber connection isolation valve, preferably, the minimum identification position is 2000-2400 mm higher than the seed crystal zero position. Wherein, the seed crystal zero position is the position where the lower edge surface of the graphite chuck of the seed crystal is flush with the lower edge surface of the flow guide cylinder.

[0088] After successful identification, automatically control the suction tool to descend to a position 1600-1800 mm above the seed crystal zero position.

[0089] Then judge whether the suction tool shakes or not through the CCD observation window set on the outer wall of the main chamber, specifically as follows:

[0090] If the suction tool is still shaking within the set time, the system automatically alarms, indicating that the suction tool is not stable, prompting the operator to switch to manual control of the suction tool stability control.

[0091] If not, it means that the suction tool has been stably hoisted, and the system automatically executes the next step of the sub-chamber purification program.

[0092] S232, sub-chamber purification.

[0093] Control the suction tool to rise to the minimum identification position of 2000-2400 mm, at this time the isolation valve of the sub-chamber is still closed.

[0094] Purify the sub-chamber, that is, the suction tool is still suspended and isolated at the minimum identification position in the sub-chamber, and the air in the sub-chamber is purified, the purification time and air pressure are preset programs and are automatically executed.

[0095] After the sub-chamber purification is completed, open the isolation valve on the sub-chamber and control the suction tool to enter the main chamber.

[0096] S233, stepwise preheating of the suction tool.

[0097] Pre-set at least two times of static preheating of the suction tool, and with the increase of the descending depth of the suction tool, the time of each static preheating is prolonged by 4-10 min than the previous time.

[0098] Specifically, the system automatically controls the suction tool to first descend to a position at a height of 500-600 mm from the seed crystal zero position, preferably, the first preheating position is arranged inside the water cooling jacket near the lower end surface on one side, and the lower end surface of the suction tool is also inside the water cooling jacket; and the first preheating time is 1-2 min. Because the suction tool directly enters the high-temperature main chamber from the room-temperature auxiliary chamber, the step heating avoids the phenomenon of burst of the suction tool caused by heating.

[0099] Then, the suction tool continues to descend to a position at a height of 300-350 mm from the seed crystal zero position, preferably, the second preheating position is below the flow guide cylinder, and the heating time at this position is 5-9 min.

[0100] After the second preheating is completed, the system controls the suction tool to descend until it contacts the molten silicon liquid surface. The standard for the system to judge whether the suction tool contacts the liquid surface is whether the contact voltage alarm of the suction tool is received. Because the weight molybdenum and the material of the suction tool are both conductor materials, and the molten silicon is also a conductor material, when the three are connected, a conductor is formed, and the standard of the contact voltage is 0-10 V, and once the range is exceeded, a beeping alarm sound will be emitted. When the suction tool contacts the molten silicon liquid surface, the contact voltage value is negative, that is, an alarm will occur. When the system receives the contact voltage alarm of the suction tool, the suction tool is automatically adjusted to be lifted by a height of 1-5 mm from the liquid surface, and the suction tool is preheated for the third time, and the preheating time is 5-9 min. After the step heating, the overall temperature of the suction tool reaches a temperature suitable for the temperature of the molten silicon liquid surface, so that when the molten silicon enters the suction tool, the molten silicon will not be rapidly cooled and solidified due to the too low temperature of the suction tool, which is not conducive to the flow and collection of all solutions; and the phenomenon of crack caused by thermal expansion and contraction of the suction tool due to uneven heating is also avoided, and the phenomenon of silicon leakage is caused.

[0101] After the third step temperature is completed, the system controls the suction tool to descend to the liquid surface again, and judges whether the suction tool contacts the liquid surface.

[0102] Once the suction tool contacts the liquid surface, the contact voltage will alarm, and when the contact voltage alarm of the suction tool is received, the system automatically adjusts the rotation of the quartz crucible to 1 r / min, indicating that the preheating is completed.

[0103] S234, pressurize, and suck the remaining material at the bottom of the crucible.

[0104] When the contact voltage alarm of the suction tool is received, the suction tool is controlled to descend to 20-45 mm from the liquid surface, that is, the suction tool is descended to 20-45 mm from the liquid surface, so that the suction head of the suction tool is completely immersed in the solution, thereby ensuring the sealing performance and safety of the inner cavity of the suction tool.

[0105] After the suction tooling is lowered into the solution, the system automatically controls the quartz crucible to stop rotating at 1 r / min and the suction tooling to remain stationary.

[0106] The system automatically exits the pressure control program and quickly charges the sub-chamber to the standard suction pressure value. That is, when the pressure control program is exited, the system controls the opening of the throttle valve in the main chamber to jump to 0%, automatically opens the fast charging valve, and closes the ball valve. When the main chamber is quickly pressurized to 190-200 torr, the pressure on the outer wall of the suction tooling is greater than the pressure in the inner cavity, causing the suction tooling to have a pressure difference, thereby forcing the solution to be sucked into the inner cavity of the suction tooling.

[0107] After the suction is completed, the ball valve is automatically opened and the opening of the throttle valve is opened to 15%.

[0108] When the gravity sensor monitoring the suction tooling detects that the weight of the suction tooling after suction is greater than its weight before suction, and the suction tooling is stable, it indicates that the suction is complete.

[0109] S235, cooling the suction tooling after suction.

[0110] Start the quartz crucible to rotate at a low speed and maintain at 1 r / min; at the same time, control the suction tooling to automatically and slowly rise step by step and remain stationary for a period of time.

[0111] Specifically, when the suction tooling carrying the remaining material rises to the water cooling jacket, that is, the height from the seed crystal zero position is 300-350 mm, it is stationary for 15-20 min to gradually solidify the molten material in the suction tooling in the main chamber.

[0112] Turn the isolation valve of the sub-chamber to allow the suction tooling carrying the remaining material to rise to the sub-chamber and to the lowest point of the recognition position, that is, the height from the seed crystal zero position is 2000-2400 mm, and then remain stationary for 20-25 min. The temperature in the sub-chamber is lower than that in the main chamber, which is beneficial to the heat dissipation of the suction tooling. Since the molten material in the inner cavity of the suction tooling still has a certain residual temperature, it needs to be further cooled for a longer time than in the water cooling jacket to completely solidify the molten silicon material in the inner cavity of the suction tooling.

[0113] After the second cooling of the suction tooling is completed, the fast charging valve is automatically closed and the pressure control program is started to ensure that the pressure in the main chamber is within the control range.

[0114] Turn the sub-chamber and remove the suction tooling carrying the remaining material.

[0115] Thus, the automatic suction work is completed.

[0116] Then manually take out the suction tooling; the sub-chamber resets, ready for the next step of re-throwing work.

[0117] The following is a preferred embodiment of the application, taking a single crystal silicon rod with a drawing diameter of 300 mm as an example to further illustrate the automatic control suction method:

[0118] Example 1:

[0119] S1, determine whether to take section suction.

[0120] S11, get the lifetime value and resistivity of the first single crystal silicon rod that has been drawn, and continue to operate the single crystal silicon rod being drawn.

[0121] The lifetime value and resistivity of the head end surface of the first single crystal silicon rod were measured to be 138us and 0.3Ω·m, respectively.

[0122] S12, determine whether the lifetime value of the first single crystal silicon rod and the ratio of the lifetime value to the resistivity are qualified.

[0123] As can be seen from S11, the lifetime value is 138us, which is greater than the set value of 120-125us; and the ratio of the lifetime value to the resistivity is 460, which is greater than the set value of 150-250.

[0124] Therefore, it indicates that the lifetime value and the ratio of the lifetime value to the resistivity of the first single crystal are both qualified, meeting the parameter requirements of the crystal, and the single crystal silicon rod being drawn is continued to be operated, and the re-throwing drawing program is continued to be executed.

[0125] S13, get the lifetime value and resistivity of the second single crystal silicon rod that has been drawn, and continue to operate the single crystal silicon rod being drawn.

[0126] After the second single crystal silicon rod is drawn, its lifetime value and resistivity are tested, and the lifetime value is measured to be 130us and the resistivity is measured to be 0.4Ω·m.

[0127] S14, determine whether the lifetime value of the second single crystal silicon rod and the ratio of the lifetime value to the resistivity are qualified.

[0128] As can be seen from S13, the lifetime value is 130us, which is greater than the set value of 120-125us; and the ratio of the lifetime value to the resistivity is 325, which is greater than the set value of 150-250.

[0129] Therefore, it indicates that the lifetime value and the ratio of the lifetime value to the resistivity of the second single crystal are both qualified, meeting the parameter requirements of the crystal, and the single crystal silicon rod being drawn is continued to be operated, and the re-throwing drawing program is continued to be executed.

[0130] S15, get the lifetime value and resistivity of the third single crystal silicon rod that has been drawn, and continue to operate the single crystal silicon rod being drawn.

[0131] After the third single crystal silicon rod is drawn, the lifetime value and resistivity are tested, and the lifetime value is measured as 120 us and the resistivity is measured as 0.5 Ω·m.

[0132] S16, judge whether the lifetime value of the third single crystal silicon rod and the ratio of the lifetime value to the resistivity are qualified.

[0133] From S15, the lifetime value 120 us is equal to the lower limit value 120 us in the set value 120-125 us; and the ratio of the lifetime value to the resistivity is 240, which is within the set value 150-250.

[0134] Then it is indicated that the lifetime value of the third single crystal and the ratio of the lifetime value to the resistivity are not qualified.

[0135] If the lifetime value and the ratio of the lifetime value to the resistivity are not greater than the set value, it is indicated that the quality of the single crystal silicon rod is not qualified, which does not meet the parameter requirements of the crystal, and the fourth single crystal silicon rod being drawn is continued to be operated, and the program of taking and sucking is jumped to, that is, after the fourth single crystal silicon rod is drawn, the taking and sucking is started to be executed.

[0136] S2, the program of taking and sucking.

[0137] S21, the single crystal silicon rod being drawn is taken out.

[0138] After the last single crystal silicon rod being drawn is taken out from the surface of the molten silicon, the height of the crucible position of the quartz crucible is lowered to 280 mm from the zero position of the quartz crucible.

[0139] At the same time, the power of the main heater and the power of the bottom heater are increased, so that the power of the main heater is 10-15 kw higher than that of the main heater during the crystal pulling, and the power of the bottom heater is 15-20 kw higher than that of the main heater during the crystal pulling.

[0140] When the rotating speed of the quartz crucible is reduced to 1 r / min, the single crystal silicon rod being drawn is automatically executed to the cooling process.

[0141] When the single crystal silicon rod enters the secondary chamber, the isolation valve of the secondary chamber is closed, and the secondary chamber is controlled to be opened, and the single crystal silicon rod is placed in the crystal taking barrel for cooling.

[0142] S22, judge whether the remaining material weight in the quartz crucible is within the safe range.

[0143] After the single crystal silicon rod being drawn is taken out, the remaining material in the quartz crucible is measured as 15 kg, which is less than the standard 25 kg, and the next step of the sucking process is started to be executed.

[0144] S23, the sucking process.

[0145] S231, install and stabilize the suction tooling.

[0146] Manually disassemble the seed crystal chuck tooling installed on the weight, and then manually install the suction tooling.

[0147] After the suction tooling is installed, tighten the sub-chamber.

[0148] Judge and identify the successful installation of the suction tooling, and automatically raise the suction tooling to a position 2400mm above the seed crystal zero position.

[0149] After the suction tooling is successfully identified, automatically control the suction tooling to descend to a position 1800mm above the seed crystal zero position.

[0150] After the suction tooling is not shaken, continue to execute the next step of the sub-chamber purification program.

[0151] S232, sub-chamber purification.

[0152] Control the suction tooling to rise to the minimum identification position 2400mm, at which time the isolation valve of the sub-chamber is still closed.

[0153] Fix the position height of the suction tooling unchanged, and purify and isolate the sub-chamber.

[0154] After the sub-chamber purification is completed, open the isolation valve on the sub-chamber, and control the suction tooling to enter the main chamber.

[0155] S233, stepwise preheating of the suction tooling.

[0156] First, control the suction tooling to descend to a height position 600mm above the seed crystal zero position for the first preheating for 1min.

[0157] Then control the suction tooling to continue to descend to a height position 350mm above the seed crystal zero position for the second preheating for 5min.

[0158] After the second preheating is completed, the system controls the suction tooling to descend until it contacts the molten silicon liquid surface.

[0159] When the system receives the contact voltage alarm of the suction tooling, automatically adjust the suction tooling to ascend to a position 5mm above the liquid surface, and perform the third stationary preheating of the suction tooling for 5min.

[0160] After the third step temperature is completed, the system controls the suction tooling to descend to the liquid surface again.

[0161] When the contact voltage alarm of the suction tooling is received, the system automatically adjusts the crucible rotation of the quartz crucible to 1r / min, and the preheating is completed.

[0162] S234, pressurization and suction of the remaining material at the bottom of the crucible.

[0163] When the contact voltage alarm of the suction tool is received, the suction tool is controlled to descend to a position 20mm below the liquid surface.

[0164] The system automatically controls the quartz crucible to stop rotating directly from 1r / min, and controls the suction tool to be stationary.

[0165] After the suction tool reaches the specified position, pressure charging and suction are performed, at this time, the system automatically closes the pressure control program, the throttle valve is returned to 0, the crucible rotation is returned to 0, the ball valve is closed, the fast charging valve is opened, and the suction is performed; when the furnace pressure in the main chamber reaches 200torr, the fast charging valve is closed, the ball valve is automatically opened, the throttle valve is jumped to 15%, and the pressure control module is automatically opened.

[0166] When the gravity sensor monitors that the weight of the suction tool after suction is 42kg, which is greater than the weight of 20kg before suction, and the suction tool is stationary, the suction is completed.

[0167] S235, the suction tool after suction is cooled.

[0168] The rotation speed of the quartz crucible is started to be 1r / min.

[0169] When the suction tool carrying the remaining material is controlled to ascend to a height of 350mm from the seed crystal zero position, it is stationary and cooled for 15min.

[0170] When the isolation valve of the auxiliary chamber is rotated open, the suction tool carrying the remaining material ascends to the auxiliary chamber and reaches the lowest point of the identification position at a position of 2400mm, and then is stationary and cooled for 20min.

[0171] After the secondary cooling is completed, the fast charging valve is automatically closed again, and the pressure control program is started to ensure that the pressure in the main chamber is within the control range.

[0172] The auxiliary chamber is rotated open, and the suction tool carrying the remaining material is taken out.

[0173] 1. The automatic control suction method in the direct pulling single crystal process designed by the application can accurately judge the suction condition, does not need personnel intervention operation, maximally reduces human error, improves work efficiency, shortens the operation time from the existing 3-4h of two persons to 1-2h of a single person, and can also ensure the completeness of the suction, so that the suction tool can be repeatedly used and the production progress is improved.

[0174] 2. The suction method disclosed by the application can realize automatic control in the whole process, each step is automatically judged and controlled by the machine system, personnel intervention operation is not needed, few people or no people are realized, personnel cost is maximally saved, and production efficiency is improved.

[0175] 3. Realize automatic positioning of liquid level position and suction position, from the previous uncertain position to the position when the suction nozzle contacts the liquid level, the system automatically reports the alarm mode of contact voltage to control the third preheating of the suction tool and the suction tool is immersed into the liquid level position below 20-45mm to perform suction.

[0176] 4. Meanwhile, the ladle position and the throttle valve can be automatically adjusted, so that after the suction tool reaches the specified position, it directly enters the pressure charging and suction, at this time the system automatically closes the pressure control program, the throttle valve returns to 0, the ladle returns to 0, the ball valve is closed, the fast charging valve is opened, and the suction is performed; when the furnace pressure in the main chamber reaches 200torr, the fast charging valve is closed, the ball valve is automatically opened, the throttle valve jumps to 15%, and the pressure control module is automatically opened.

[0177] The above detailed description of the embodiments of the present application is only the preferred embodiments of the present application, and cannot be considered as limiting the scope of the present application. Any equivalent changes and improvements made according to the scope of the present application should still belong to the patent coverage scope of the present application.

Claims

1. A method for automatically controlling the pulling of a single crystal in a single crystal pulling process, the method comprising the steps of: The application relates to a method for controlling the drawing of a single crystal silicon rod. ​ The method comprises the following steps: acquiring the minority carrier lifetime value and the resistivity of a single crystal silicon rod which has been drawn, and continuing to draw the single crystal silicon rod; judging the minority carrier lifetime value of the single crystal silicon rod which has been drawn and the ratio of the minority carrier lifetime value to the resistivity, if the minority carrier lifetime value and the ratio of the minority carrier lifetime value to the resistivity are both greater than corresponding set values, a re-drawing process is continued; 2. The method according to claim 1, wherein the method is characterized by: if the minority carrier lifetime value and / or the ratio of the minority carrier lifetime value to the resistivity is not greater than the corresponding set value, a segment suction process is executed.

3. The method according to claim 1 or 2, wherein the method is characterized by, The minority carrier lifetime value and the resistivity are both test values of the same position of the head of the single crystal silicon rod which has been drawn.

4. The method according to claim 3, wherein the method is characterized by: The set value of the minority carrier lifetime value is 120-125 us.

5. The method according to any one of claims 1-2, 4, wherein the method is used in a Czochralski process, and the method comprises the following steps: The set value of the ratio of the minority carrier lifetime value to the resistivity is 150-250. ​ The segment suction process specifically comprises the following steps: judging whether the remaining material in a quartz crucible is within a safe range; if yes, the drawing of the single crystal silicon rod is continued until the weight of the remaining material in the quartz crucible is not greater than 25 kg; 6. The method of claim 5, wherein the method further comprises: if no, the drawing of the single crystal silicon rod is stopped, and a suction process is started. Before the execution of the suction process, the method comprises the following steps: after the last single crystal silicon rod being drawn is taken out and is away from the surface of the molten silicon, the position of the quartz crucible is controlled to be lowered to a set suction position; and the power of a main heater and the power of a bottom heater are increased; when the rotating speed of the quartz crucible is lowered to 1-2 r / min, 7. The method of claim 6, wherein the method further comprises: determining a position of the seed crystal; and adjusting the position of the seed crystal based on the determined position of the seed crystal. a cooling process is automatically executed on the single crystal silicon rod being drawn. The increase of the power of the main heater and the power of the bottom heater comprises the following steps: the power of the main heater is 10-15 kw higher than that of the main heater during crystal pulling, and the power of the bottom heater is 15-20 kw higher than that of the main heater during crystal pulling; 8. The method according to claim 6 or 7, wherein the method is used in a Czochralski process for pulling a single crystal, and the method comprises the steps of: the power of the main heater and the power of the bottom heater are fixed values during the suction process until the end of the suction process. ​ The suction process comprises the following steps: purification of a secondary chamber; gradient preheating of a suction tool for the suction process; 9. The method of claim 8, wherein the method further comprises: determining a position of the seed crystal in the crucible; and adjusting the position of the seed crystal in the crucible based on the determined position of the seed crystal in the crucible. suction of the remaining material at the bottom of the crucible. The gradient preheating of the suction tool comprises the following steps: at least twice preheating of the suction tool is set, and with the increase of the lowering depth of the suction tool, the preheating time of each time is prolonged by 4-10 min longer than that of the previous time; the lowering of the suction tool is controlled, and whether the suction tool is in contact with the surface of the molten silicon is judged; when the contact voltage alarm of the suction tool is received, the suction tool is adjusted to be lifted by 1-5 mm, and preheating is performed again for a certain time; the lowering of the suction tool to the surface of the molten silicon is controlled again, and whether the suction tool is in contact with the surface of the molten silicon is judged; 10. The method of claim 9, wherein the method further comprises: determining a position of the seed crystal; and adjusting the position of the seed crystal based on the determined position of the seed crystal. when the contact voltage alarm of the suction tool is received, the rotating speed of the quartz crucible is adjusted to be 1 r / min, and the preheating is completed. Before the purification of the secondary chamber, whether the suspension of the suction tool is stable is judged, and the steps comprise the following steps: whether the suction tool is identified and determined is first judged; whether the suction tool shakes is then judged; if yes, an alarm is given to switch to manual stable control; 11. An automatic control feeding method in a Czochralski single crystal process according to claim 9 or 10, characterized in that, if no, the purification of the secondary chamber is executed. The purification of the secondary chamber comprises the following steps: the suction tool is lifted to a minimum identification position; the secondary chamber is isolated for purification; The isolation valve on the sub-chamber is opened again, and the suction tool is controlled to enter the main chamber.

12. The method of claim 11, wherein the method further comprises: determining a position of the seed crystal; and adjusting the position of the seed crystal based on the determined position of the seed crystal. The remaining material in the suction cup bottom includes the following steps: When the contact voltage alarm of the suction tool is received, the suction tool is controlled to descend to 20-45mm below the liquid level; The quartz crucible stops rotating, and the suction tool is stationary; The pressure control program is exited, and the sub-chamber is rapidly pressurized to the standard suction pressure value, and the suction begins; When the weight of the suction tool after suction is greater than its weight before suction and is stable, the suction is completed.

13. The method of claim 12, wherein the method further comprises: determining a position of the seed crystal; and adjusting the position of the seed crystal based on the determined position of the seed crystal. The remaining material in the suction cup bottom also includes cooling the suction tool after suction, and the steps include: The quartz crucible is started at a low speed; When the suction tool with remaining material rises into the water cooling jacket, it is stationary for a period of time; When it rises into the sub-chamber and reaches the lowest point of the recognition position, it is stationary for a period of time, and the cooling time is longer than in the water cooling jacket; The pressure control program is started; The sub-chamber is rotated and the suction tool is removed.

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