JP5817239B2 - Method and apparatus for pulling semiconductor single crystal - Google Patents

Description

  The present invention relates to a method for pulling a semiconductor single crystal such as a silicon single crystal and an apparatus for pulling the semiconductor single crystal.

  Conventionally, as a method for pulling up this type of semiconductor single crystal, when the heating temperature pattern is set in advance and the single crystal is grown by the Czochralski method, the heating temperature of the heating means for heating the raw material melt is set to the diameter of the single crystal. Based on the response characteristics, the heating temperature that changes during the growth of the single crystal is subdivided at regular intervals to identify the amount of change in diameter corresponding to each step change, and these diameter changes can be superimposed. By comparing the crystal diameter with the target diameter and making adjustments to eliminate these errors, the change over time in the diameter of the single crystal relative to the heating temperature pattern can be changed at least for each single crystal growth device or single crystal growth. Predicted for each history of the parts that make up the device, and adjusted and determined so that the predicted diameter value matches the preset length target value for the pulling length or pulling time. Method for growing a single crystal of heating the raw material melt on the basis of the temperature pattern is disclosed (e.g., see Patent Document 1.). In this single crystal growth method, the heating temperature pattern subdivides the heating temperature that changes during the growth process of the single crystal at regular intervals to identify the diameter change amount corresponding to each step change amount, and It is determined by comparing the diameter of the single crystal formed by superimposing the diameter variation and the target diameter, and adjusting so as to eliminate these errors.

  In the method of growing a single crystal thus configured, the raw material melt is heated based on a predetermined heating temperature pattern, so that even a single crystal having a large diameter can be grown while accurately controlling its diameter. it can. In particular, it is suitable for shape control of the shoulder part up to the straight body part which becomes the target diameter of the single crystal. Further, it is possible to absorb the influence on the diameter of the heating temperature pattern, which is different for each single crystal growing apparatus or for each history of parts constituting the single crystal growing apparatus. That is, the heating temperature is subdivided, and the temperature (step change) changed in each part changes the diameter of the single crystal, and fine adjustment is possible by measuring the change in the diameter of the single crystal finely. Become. As a result, the best heating temperature pattern can be obtained by finely adjusting the diameter of the single crystal formed by superimposing the diameter variation in each part, that is, by finely adjusting so as to eliminate the error from the target diameter. It can be created.

Japanese Patent No. 4039055 (Claims 1 and 2, paragraphs [0011] and [0013])

  However, when the method for growing a single crystal shown in the above-mentioned conventional Patent Document 1 is applied to the control for pulling up the diameter of the straight body of the single crystal to be constant, it can be expected during the pulling of the single crystal. When there was no disturbance, the temperature profile of the heater deviated from the initial setting value, and there was a risk that the diameter fluctuation of the single crystal would become large.

  The first object of the present invention is to reduce the fluctuation of the diameter of the single crystal and to suppress the fluctuation of the pulling speed, which is an operation amount for controlling the diameter of the single crystal, when there is no unexpected disturbance during the pulling. If an unforeseen disturbance occurs during pulling, the diameter fluctuation of the single crystal is reduced, and the fluctuation of the pulling speed, which is the manipulated variable for controlling the diameter of the single crystal, can be suppressed. It is an object of the present invention to provide a method for pulling a semiconductor single crystal and a pulling apparatus for the same, which can suppress the influence on the semiconductor and thereby can manufacture a high-quality semiconductor single crystal. The second object of the present invention is to improve the temperature profile of the heater by correcting the temperature profile of the single crystal heater to be pulled up next before pulling up based on the reliability and weighting factor of the first evaluation function. It is an object of the present invention to provide a method for pulling a semiconductor single crystal and a pulling apparatus for the same. A third object of the present invention is to provide a single crystal pulling method and its pulling apparatus, which can improve the accuracy of automatic correction of the temperature profile of a heater performed during pulling of the single crystal. The fourth object of the present invention is to estimate the starting point of the monotonic increase of the heater temperature, and automatically correct the heater temperature profile by causing the heater temperature profile to be automatically corrected after the monotonic increasing start point is exceeded. It is an object of the present invention to provide a semiconductor single crystal pulling method and a pulling apparatus thereof capable of efficiently exhibiting the function. A fifth object of the present invention is to provide a semiconductor single crystal pulling method capable of reducing large irregularities caused by a temperature profile of a heater after automatic correction by applying a leveling function to the temperature profile of the heater after automatic correction, and The object is to provide such a lifting device.

According to a first aspect of the present invention, a semiconductor raw material supplied to a crucible of a semiconductor single crystal pulling apparatus is melted by a heater, a semiconductor melt is stored in the crucible, and a temperature profile preset in the pulling apparatus is used. In a method for pulling a semiconductor single crystal that pulls the semiconductor single crystal from the semiconductor melt in the crucible while controlling the heater, a step of accumulating in the database past pulling data of the semiconductor single crystal that contributes to setting of the temperature profile of the heater; The step of evaluating the temperature profile of the next silicon single crystal heater to be pulled up from the previous pulling data of the semiconductor single crystal stored in the database based on the first evaluation function and the next pulling based on the first evaluation function The process of modifying the temperature profile of the semiconductor single crystal heater to be raised before pulling, and the modified temperature profile A step of pulling the semiconductor single crystal from the semiconductor melt in the crucible while controlling the heater, and further automatically correcting the corrected temperature profile for each predetermined pulling length during the pulling of the semiconductor single crystal. In the past, the semiconductor single crystal is pulled from the semiconductor melt in the crucible while controlling the heater based on the automatically corrected temperature profile, and the first evaluation function is fed back to the temperature profile of the next semiconductor single crystal heater to be pulled up. Reliability determined from the proximity of the temperature profile setting value and actual value of the semiconductor single crystal heater, the next pulling condition of the semiconductor single crystal to be pulled up next, and the temperature of the semiconductor single crystal heater to be pulled up next Of the past semiconductor single crystal pull-up data fed back to the profile, the set pull-up conditions and And a weighting factor determined from the proximity of the actual pulling conditions, characterized in that next to modify the temperature profile of a pulling Ru semiconductor single crystal of the heater before pulling on the basis of the reliability and the weight coefficient.

A second aspect of the present invention is the invention based on the first aspect, and further, the automatic correction function of the heater temperature profile is in the process of pulling up the semiconductor temperature and the immediately preceding heater temperature gradient during the semiconductor single crystal pulling up. Obtained by this second evaluation function, and a second evaluation function for evaluating a candidate heater temperature inclination to be automatically corrected next based on the difference between the heater temperature measured in this time and the heater temperature inclination based on the heater temperature measured this time And a determination function for determining a heater temperature gradient to be automatically corrected next based on the result.

A third aspect of the present invention is an invention based on the first or second aspect , further inferring a monotonically increasing start point of the heater temperature during pulling of the semiconductor single crystal, and an automatic correction function of the heater temperature profile Is exhibited after exceeding the monotonous increase start point of the heater temperature.

A fourth aspect of the present invention is an invention based on any one of the first to third aspects, and the automatic correction function of the heater temperature profile is such that the automatically corrected heater temperature profile maintains continuity. It further has a leveling function for performing leveling calculation on the temperature profile of the automatically corrected heater.

According to a fifth aspect of the present invention, the semiconductor raw material supplied to the crucible is melted by the heater, the semiconductor melt is stored in the crucible, and the controller controls the heater based on a preset temperature profile. In a semiconductor single crystal pulling apparatus configured to pull a semiconductor single crystal from a semiconductor melt, the controller accumulates past pulling data of the semiconductor single crystal contributing to setting of the temperature profile of the heater in the database, and the database The semiconductor single crystal heater temperature profile to be pulled up next is evaluated based on the first evaluation function based on the past semiconductor single crystal pull-up data accumulated in the first evaluation function. Set value of the temperature profile of the past semiconductor single crystal heater fed back to the heater temperature profile Reliability determined from closeness to the actual value, past pulling data of the semiconductor single crystal fed back to the set pulling condition of the next semiconductor single crystal to be pulled up and the temperature profile of the next semiconductor single crystal heater to be pulled up A semiconductor single crystal heater having a weighting factor determined based on the set pulling condition and the proximity of the actual pulling condition when compared with the actual pulling condition, and the next pulling based on the reliability and the weighting factor The semiconductor single crystal is pulled up from the semiconductor melt in the crucible while controlling the heater based on the corrected temperature profile, and the semiconductor single crystal is pulled up for each predetermined pulling length during the pulling of the semiconductor single crystal. The modified temperature profile is further automatically corrected, and the heater is controlled based on the automatically corrected temperature profile, while the half of the crucible in the crucible is controlled. Characterized in that it is configured to pull the semiconductor single crystal from KaradaTorueki.

A sixth aspect of the present invention is the invention based on the fifth aspect , and further, the automatic correction function of the heater temperature profile is a heater temperature gradient that is automatically corrected immediately before the semiconductor single crystal is being pulled up. Based on the difference between the heater temperature measured immediately before and the heater temperature gradient based on the heater temperature measured this time, a second evaluation function that evaluates the candidate heater temperature gradient to be automatically corrected next is obtained by this second evaluation function. And determining a heater temperature gradient based on the result, and the controller is configured to automatically correct the temperature profile of the heater based on the second evaluation function and the determination function.

A seventh aspect of the present invention is the invention based on the fifth or sixth aspect , and the controller further estimates a monotonically increasing start point of the heater temperature during the pulling of the semiconductor single crystal, and determines the heater temperature profile. The automatic correction function is configured to be exhibited after the start point of the monotonous increase of the heater temperature.

An eighth aspect of the present invention is an invention based on any one of the fifth to seventh aspects, and the controller further controls the temperature of the automatically corrected heater so that the temperature profile of the automatically corrected heater is maintained. It is characterized in that it is configured to perform a leveling calculation on the profile.

  In the pulling method according to the first aspect and the pulling apparatus according to the fifth aspect of the present invention, the past single crystal pull data contributing to the setting of the temperature profile of the heater is accumulated in a database, and the past single crystal pull data is stored. Next, the temperature profile of the single crystal heater to be pulled up next is evaluated based on the first evaluation function, and the temperature profile of the single crystal heater to be pulled up next based on the first evaluation function is corrected before pulling, The single crystal is pulled up while controlling the heater based on the modified temperature profile, so if there is no unforeseen disturbance during pulling, the single crystal diameter variation is reduced and the single crystal diameter control operation amount It is possible to suppress fluctuations in the pulling speed. During the pulling of the single crystal, the modified temperature profile is further automatically corrected for each predetermined pulling length, and the single crystal is pulled while controlling the heater based on the automatically corrected temperature profile. If an unforeseen disturbance occurs, the fluctuation of the single crystal diameter can be reduced, and the fluctuation of the pulling speed, which is the manipulated variable of the single crystal diameter control, can be suppressed. The effect on it can be suppressed. As a result, a high-quality single crystal can be produced even if an unforeseen disturbance does not occur during the pulling of the single crystal or an unpredictable disturbance occurs during the pulling of the single crystal.

  In addition, the disturbance expected during the next pulling of the single crystal is not taken into account in the heating temperature pattern, and when applied to the control of pulling up the straight body of the single crystal, the diameter variation of the single crystal may increase. In addition, if an unforeseen disturbance occurs during pulling of the single crystal, the temperature profile of the heater may deviate from the initial setting value, and the diameter variation of the single crystal may be further increased. In the present invention, in the present invention, the temperature profile of the next single crystal heater is evaluated based on the first evaluation function based on the previous single crystal pull data, and the next pull is performed based on the first evaluation function. By modifying the temperature profile of the single crystal heater to be raised before pulling, the disturbance expected during pulling is added to the heating temperature pattern before pulling and the heater temperature during pulling is increased. B automatically modify the file to a predetermined pull-up length per, pulling a single crystal while controlling the heater based on the temperature profile of the automatic modified heater. As a result, in the present invention, when the straight body of the single crystal is pulled up, fluctuations in the diameter of the single crystal can be suppressed, the target diameter can be maintained, and unpredictable disturbances that occur during the pulling can be caused in the heater temperature. Since the influence can be suppressed, a high-quality single crystal can be manufactured.

Furthermore, since the temperature profile of the single crystal heater to be pulled up next is corrected before pulling up based on the reliability and weighting factor of the first evaluation function, high accuracy of the heater temperature profile can be realized.

In the pulling method of the second aspect and the pulling apparatus of the sixth aspect of the present invention, the heater temperature profile is automatically corrected based on the second evaluation function and determination function of the heater temperature profile automatic correction function. The accuracy of the automatic correction of the temperature profile of the heater that is performed during the pulling of the crystal can be improved.

In the pulling method according to the third aspect and the pulling apparatus according to the seventh aspect of the present invention, a monotonically increasing start point of the heater temperature during the pulling of the single crystal is estimated, and the temperature profile of the heater is exceeded after the monotonically increasing start point is exceeded. The automatic correction function of the heater temperature profile can be exhibited more quickly than when the automatic correction function of the temperature profile of the heater is exhibited after determining the monotonic increase start point from the actual measurement value. As a result, the automatic correction function of the heater temperature profile can be efficiently exhibited.

In the pulling method according to the fourth aspect and the pulling apparatus according to the eighth aspect of the present invention, the leveling function during pulling out of the automatic correction function of the heater temperature profile maintains the continuity of the automatically corrected heater temperature profile. As described above, the smoothing calculation is performed for the automatically corrected heater temperature profile.If the heater temperature profile becomes uneven by automatically correcting the heater temperature profile during pulling, The unevenness is relaxed and brought closer to the average value of the gradient of the temperature profile in the section. As a result, large irregularities generated in the temperature profile of the heater after automatic correction can be reduced.

It is a longitudinal cross-sectional block diagram of the pulling apparatus of the silicon single crystal of embodiment of this invention. It is a figure which shows the change of the temperature gradient deviation (difference between the setting value of a heater temperature gradient, and a track record value) with respect to the change of the pulling length of the past single crystal. It is a figure which shows the change of the acceptance rate (acceptance rate with respect to the threshold value set to the temperature gradient deviation of a heater) with respect to the change of the pulling length of the past single crystal. It is a figure which shows the state before and behind equalizing a heater temperature inclination by the factor 0.8. It is a figure which shows the state before and after leveling a heater temperature inclination by the leveling coefficient of 0.2. It is a figure which respectively shows the case where appropriate correction | amendment, excessive correction | amendment, and reverse correction are performed with respect to the heater temperature inclination during the pulling of a single crystal. It is a figure which shows the change of the heater temperature with respect to the change of the pulling length of a single crystal. It is a flowchart figure which shows the procedure which corrects and determines a heater temperature profile before pulling up the single crystal. It is a flowchart figure which shows the procedure of the first half which corrects the temperature profile of a heater automatically during the pulling of the single crystal. It is a flowchart figure which shows the procedure of the second half which corrects the temperature profile of a heater automatically during the pulling of the single crystal. It is a figure which shows the change of the diameter standardization value [diameter actual value / diameter average value] of the silicon single crystal with respect to the change of the pulling rate of the single crystal of Example 1. It is a figure which shows the change of the diameter standardization value [diameter actual value / diameter average value] of the silicon single crystal with respect to the change of the pulling rate of the single crystal of the comparative example 1.

  Next, an embodiment for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the pulling device for the silicon single crystal 11 includes a main chamber 12 configured to be vacuumable inside, and a crucible 13 provided in the center of the chamber 12. The main chamber 12 is a cylindrical vacuum container. The crucible 13 includes a bottomed cylindrical inner layer container 13a formed of quartz and storing the silicon melt 14, and a bottomed cylindrical outer layer container 13b formed of graphite and fitted to the outside of the inner layer container 13a. It consists of. The upper end of the shaft 16 is connected to the bottom of the outer layer container 13b, and a crucible driving means 17 for rotating and raising / lowering the crucible 13 via the shaft 16 is provided at the lower end of the shaft 16. Further, the outer peripheral surface of the crucible 13 is surrounded by a cylindrical heater 18 at a predetermined interval from the outer peripheral surface of the crucible 13, and the outer peripheral surface of the heater 18 is predetermined from the outer peripheral surface of the heater 18 by a cylindrical heat retaining cylinder 19. Surrounded at intervals.

  On the other hand, a cylindrical pull chamber 21 having a smaller diameter than the main chamber 12 is connected to the upper end of the main chamber 12 so as to communicate with the inside. A pulling rotation means 22 is provided at the upper end of the pull chamber 21. The pulling rotation means 22 is configured to move up and down a pulling shaft 24 with a seed chuck 23 attached to the lower end, and to rotate the pulling shaft 24 about its axis. A seed crystal 26 is detachably attached to the seed chuck 23. After immersing the lower end of the seed crystal 26 in the silicon melt 14, the seed crystal 26 is rotated and pulled up by the pulling and rotating means 22, and the crucible 13 is rotated and raised by the crucible driving means 17. The silicon single crystal 11 is pulled up and pulled up from the lower end of the crystal 26.

  An inert gas such as argon gas is circulated in the main chamber 12. One end of a gas supply pipe 27 is connected to the side wall of the pull chamber 21, and the other end of the gas supply pipe 27 is connected to a tank (not shown) for storing an inert gas. One end of a gas discharge pipe 28 is connected to the lower wall of the main chamber 12, and the other end of the gas discharge pipe 28 is connected to the suction port of the vacuum pump 29. The inert gas in the tank is introduced into the pull chamber 21 through the gas supply pipe 27, passes through the main chamber 12, and is then discharged from the main chamber 12 through the gas discharge pipe 28. . The gas supply pipe 27 and the gas discharge pipe 28 are respectively provided with first and second flow rate adjusting valves 31 and 32 for adjusting the flow rate of the inert gas flowing through these pipes.

  In the main chamber 12, a heat shield 33 is provided for blocking the irradiation of the radiant heat of the heater 18 to the outer peripheral surface of the silicon single crystal 11 and rectifying the inert gas. The heat shield 33 has a truncated cone-like cylindrical body that gradually decreases in diameter as it goes downward and surrounds the outer peripheral surface of the silicon single crystal 11 pulled up from the silicon melt 14 at a predetermined interval from the outer peripheral surface. 33a and a flange portion 33b that is connected to the upper edge of the cylindrical body 33a and projects outward in a substantially horizontal direction. In the heat shield 33, the flange 33b is placed on the heat retaining cylinder 19 via the ring plate 33c, so that the lower edge of the cylinder 33a is positioned above the surface of the silicon melt 14 with a predetermined gap. In this way, it is fixed in the main chamber 12.

  On the other hand, a viewing window 12 a is formed on the shoulder of the main chamber 12. The viewing window 12 a includes a boundary portion between the silicon melt 14 and the seed crystal 26, a boundary portion between the silicon melt 14 and the neck portion 11 a of the silicon single crystal 11, and a shoulder portion between the silicon melt 14 and the silicon single crystal 11. The CCD camera 36 is installed so as to face the solid-liquid interface 34 that is the boundary between the silicon melt 14 and the straight body 11 c of the silicon single crystal 11. The CCD camera 36 is configured to photograph the silicon single crystal 11 being pulled up. Here, the CCD camera 36 accumulates signal charges generated by light in a capacitor formed by arranging metal film electrodes on a silicon substrate with an oxide film interposed therebetween, and the CCD camera 36 receives a drive pulse from the image processing means 37 and applies it. This is a camera that sequentially transfers in the direction and obtains an image signal that is an electrical signal. An image captured by the CCD camera 36 is processed by an image processing means 37. The detection output of the CCD camera 36 is connected to the camera control input of the image processing means 37, and the camera control output of the image processing means 37 is connected to the control input of the two-dimensional CCD camera 36. Further, the control input / output of the image processing means 37 is connected to the control input / output of the controller 38, and the control output of the controller 38 is connected to the crucible driving means 17, the heater 18 and the pulling rotation means 22. The control input / output of the controller 38 is connected to the control input / output of the image processing means 37 of all pulling devices that pull up the silicon single crystal 11 having the same diameter regardless of the type. These are connected to the crucible driving means 17, the heater 18 and the pulling rotation means 22 of all pulling devices that pull the silicon single crystal 11 having the same diameter regardless of the type.

  A storage medium 39 is connected to the controller 38. A database is stored in the storage medium 39, and the past pulling data of the silicon single crystal 11 contributing to the setting of the temperature profile of the heater 18 is accumulated in this database. The pulling data of the silicon single crystal 11 in the past includes the date when the silicon single crystal 11 is pulled, the amount of the silicon melt 14 charged into the crucible 13, the diameter of the silicon single crystal 11 taken by the CCD camera 36 at the time of pulling. Change, type of pulling device, number of pulling silicon single crystals 11 by the pulling device, next whether or not the pulling device is the same as the pulling device for pulling up the silicon single crystal 11, and parts such as the heater 18 of the pulling device were replaced. For example, the date of the withdrawal data. Examples of the storage medium 39 include an external storage medium through a network in addition to the memory.

  Further, the controller 38 is configured to evaluate the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled next from the pulling data of the silicon single crystal 11 stored in the database based on the first evaluation function. This first evaluation function is determined from the proximity of the set value and the actual value of the temperature profile of the heater 18 of the silicon single crystal 11 in the past that is fed back to the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled next. Reliability, the set pulling condition of the silicon single crystal 11 to be pulled next, and the actual pulling condition of the pulling data of the past silicon single crystal 11 fed back to the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled next And a weighting factor determined from the proximity of the set pulling condition and the actual pulling condition.

  The reliability is calculated by calculating the temperature gradient deviation of the heater 18 which is the difference between the set value of the temperature gradient in the minimum unit and the actual value in the temperature profile of the heater 18 of the silicon single crystal 11 pulled up in the past. After a threshold value is set for the temperature gradient deviation and the pass / fail is determined by comparing the temperature gradient deviation of the heater 18 with the threshold value, the temperature gradient deviation of the heater 18 over the entire length of the straight body portion 11c of the silicon single crystal 11 is determined. The acceptance rate is calculated, and the temperature profile of the heater 18 of the silicon single crystal 11 pulled in the past from the acceptance rate is evaluated. Specifically, as shown in FIGS. 2 and 3, the temperature gradient deviation of the heater 18 for each pulling length of 5 mm (minimum unit) is calculated as an average value, and the temperature gradient deviation of the heater 18 is a plurality of threshold values. (First threshold value: ± 0.002 ° C./5 mm, second threshold value: ± 0.003 ° C./5 mm), it is evaluated as good when smaller, and it is evaluated as defective when larger, When the ratio evaluated to be good is 80% or more, the pass rate for passing is calculated for every pulling length of 100 mm, and finally the pass rate is calculated over the entire length of the straight body portion 11c of the silicon single crystal 11. .

  In the portion surrounded by the one-dot chain line in FIG. 3, since the pass rate of the temperature gradient deviation of the heater 18 with respect to the first and second threshold values is low, it is evaluated that the setting is poor, and is surrounded by the two-dot chain line in FIG. In the portion, since the passing rate of the temperature gradient deviation of the heater 18 with respect to the first and second threshold values is high, it is evaluated that the setting is good. In this way, in the silicon single crystal 11 pulled in the past, it is possible to grasp in which range of the pulling length the pass rate of the temperature profile of the heater 18 was good or bad. When the temperature profile of the heater 18 of the silicon single crystal 11 pulled in the past is fed back to the temperature profile of the heater 18, the feedback amount approaches 100% if the pass rate is high, and the feedback amount is low if the pass rate is low. The reliability is determined so as to lower the value. That is, the reliability for the pass rate is stored as a map in the storage medium 39, and the controller 38 is configured to determine the reliability from the pass rate. In this embodiment, it is assumed that the temperature gradient deviation of the heater for every pulling length of 5 mm is calculated as an average value, the pass rate is calculated for every pulling length of 100 mm, and the rate evaluated as good is 80. Although it was determined to be acceptable when the value was greater than or equal to%, it is not limited to these values. In this embodiment, two threshold values are set, but one or three or more threshold values may be set.

  On the other hand, the weighting factor is a function that is determined based on the proximity between the set pulling condition of the silicon single crystal 11 to be pulled next and the actual pulling condition of the silicon single crystal 11 pulled in the past. For example, when the pulling device used for the silicon single crystal 11 to be pulled next is the same as the pulling device used for the silicon single crystal 11 pulled in the past, or when the silicon single crystal 11 to be pulled next is pulled up When the pulling date / time of the silicon single crystal 11 pulled in the past is close, the weighting factor is set high. Further, even if the pulling device used for the silicon single crystal 11 to be pulled next is the same as the pulling device used for the silicon single crystal 11 pulled in the past, parts such as the heater 18 are exchanged, or Next, when the pulling date / time of the silicon single crystal 11 to be pulled is far from the pulling date / time of the silicon single crystal 11 pulled in the past, the weighting factor is set low. That is, when the temperature profile of the heater 18 of the silicon single crystal 11 that was pulled up in the past is fed back to the temperature profile of the heater 18 of the silicon single crystal 11 that is pulled up next, the feedback amount is set to 100% if the weighting factor is high. If the weight coefficient is low, the feedback amount is determined to be low. A weighting factor for the set pulling condition and the actual pulling condition is stored as a map in the storage medium 39, and the controller 38 is configured to determine the weighting factor from the set pulling condition and the actual pulling condition. As described above, the controller 38 is configured to correct the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled up next before being pulled based on the reliability and the weighting coefficient of the first evaluation function.

  On the other hand, the controller 38 compares the pulling data of the silicon single crystal 11 to be pulled next with the pulling data of the silicon single crystal 11 to be fed back to the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled next. The difference between one or both of the constituent members used for pulling up the silicon single crystal 11 and the pulling conditions of the silicon single crystal 11 is converted into the temperature setting value of the heater 18 of the silicon single crystal 11 to be pulled up next. It is comprised so that the temperature profile of the heater 18 of the silicon single crystal 11 pulled up may be corrected.

Further, the controller 38 adjusts the temperature profile of the next silicon single crystal 11 heater 18 so as to keep the temperature profile of the next silicon single crystal 11 heater 18 to be continuous. Have When the leveling value when correcting the temperature profile of the heater 18 using the leveling function before the pulling is N, N = [K + (K ₀ −K) × R]. In this formula, interval K has irregularities of the temperature profile of the heater 18 which is set (hereinafter, referred to as uneven intervals) and heater temperature gradient of the minimum unit in, K ₀ is the mean value of the heater temperature gradient in the irregular section R is a ratio (hereinafter referred to as a smoothing coefficient) that approaches the average value K ₀ of the heater temperature gradient. This leveling coefficient is set as a constant in the range of 0-1. When the leveling coefficient is “0”, it indicates that the leveling is not performed, and when the leveling coefficient is “1”, it indicates that the leveling is performed up to the average value of the heater temperature gradient. The uneven section where the above leveling is executed is a section where the minimum unit heater temperature gradient changes from diagonally upward to diagonally downward and changes diagonally upward again, or the minimum unit heater temperature gradient changes from diagonally downward to diagonally upward again. This is a section that changes diagonally downward. Further, when the neck portion 11a and the shoulder portion 11b of the silicon single crystal 11 are pulled up, the temperature profile of the heater 18 is unstable or changes greatly, so that the leveling is not performed and the straight body portion 11c of the silicon single crystal 11 is pulled up. It is set to run in at times. Furthermore, the above-mentioned leveling is preferably performed in such a manner that the unevenness of the heater temperature gradient is not completely eliminated but the ratio of the unevenness of the heater temperature gradient is reduced. For example, if the leveling coefficient is set to about 0.8, the unevenness of the temperature gradient is excessively relaxed (FIG. 4). If the leveling coefficient is set to about 0.2, the silicon single crystal 11 is pulled manually. It has been found by trial operation that it substantially matches the setting of the setter when raising (FIG. 5).

  On the other hand, the controller 38 further automatically corrects the temperature profile of the corrected heater 18 for each predetermined pulling length during the pulling of the silicon single crystal 11, and controls the heater 18 based on the automatically corrected temperature profile. However, the silicon single crystal 11 is pulled up from the silicon melt 14 in the crucible 13. Here, each predetermined pulling length is set for each predetermined pulling length within a range of 5 to 40 mm. Further, when the straight body portion 11c of the silicon single crystal 11 is pulled up, and after exceeding a monotonous increase start point of a heater temperature described later, for example, when the straight body portion 11c is pulled up for the first 200 to 400 mm, for each predetermined pulling length. The interval for automatically correcting the temperature profile of the heater 18 even when pulling up a single silicon single crystal 11 so that every 10 mm and every predetermined pulling length every 20 mm when pulling over 400 mm. May be changed. The automatic correction function of the temperature profile of the heater 18 is a heater based on the heater temperature gradient that was automatically corrected immediately before the silicon single crystal 11 was pulled, the heater temperature measured immediately before, and the heater temperature measured this time. A second evaluation function for evaluating a candidate heater temperature gradient to be automatically corrected based on a difference from the temperature gradient; and a determination function for determining a heater temperature gradient based on a result obtained by the second evaluation function. Have.

  The second evaluation function is a function for evaluating whether the automatic correction of the heater temperature gradient is an appropriate correction, an excessive correction, or an inappropriate correction (reverse correction). In order to exhibit this function, first, the correction amount evaluation value L is calculated based on the magnitude relationship among the correction candidate heater temperature gradient K, the actual heater temperature gradient J, and the corrected heater temperature gradient S. This correction amount evaluation value L is defined by the following equation (1).

L = (K−S) / (J−S) (1)
Calculation of the correction amount evaluation value L using the above equation (1) is performed when the pulling length of the silicon single crystal 11 is between the position where the automatic correction of the heater temperature inclination is started and the position where the automatic correction is completed. Executed. Here, the heater temperature gradient is a temperature gradient of the temperature profile of the heater 18 set before the silicon single crystal 11 is pulled up. In Equation (1), the corrected heater temperature gradient S is the value of the heater 18 automatically corrected immediately before by the heater temperature gradient correction logic based on the relationship between the correction amount evaluation value L and the correction coefficient R in Table 1 described later. The temperature gradient of the temperature profile is the temperature gradient of the temperature profile of the heater 18 set before the pulling up when it is immediately after the start of automatic correction. In Equation (1), the correction candidate heater temperature gradient K is the heater temperature gradient to be automatically corrected next. Further, in Equation (1), the actual heater temperature gradient J is a heater temperature gradient calculated from the heater temperature measured immediately before and the heater temperature measured this time. This actual heater temperature gradient J is calculated, for example, by measuring the heater temperature for every 5 mm pulling length in the first 200 to 400 mm pulling range of the straight body portion 11c of the silicon single crystal 11, and the pulling range exceeding 400 mm. The heater temperature can be measured and calculated every 10 mm pulling length.

  Next, correction is performed using a table (not shown) in which parameters (the pulling time and pulling length of the silicon single crystal 11, the heater temperature inclination corrected immediately before, the actual heater temperature inclination, etc.) are set from the correction amount evaluation value L. A coefficient R is set. The setting example is shown in Table 1 below.

表１において、０＜Ｌ＜１．０の範囲を適正修正とし、この範囲では修正係数Ｒが大きく設定される。また１．０≦Ｌの範囲を過剰修正とし、この範囲では修正係数Ｒが小さく設定される。更にＬ＜０の範囲を不適正修正（逆の修正）とし、この範囲では修正係数Ｒの符号が『−』に設定される。ここで、１．０≦Ｌの範囲における修正係数Ｒを、０＜Ｌ＜１．０の範囲における修正係数Ｒより小さく設定したのは、次に自動修正するヒータ温度傾きＴが実際のヒータ温度傾きＪを越えて変化してしまうオーバーアクションを防止するためである。また、０＜Ｌ＜１．０の範囲における修正係数Ｒを、１．０≦Ｌの範囲における修正係数Ｒより大きく設定したのは、次に自動修正するヒータ温度傾きＴを実際のヒータ温度傾きＪに速やかに一致させるためである。なお、前回の実際のヒータ温度傾きＪから前回修正したヒータ温度傾きを差し引いた値が『０』であるとき、即ち修正量評価値Ｌが『０』であるとき、修正係数Ｒは修正の必要がなく『０』に設定される。また修正量評価値Ｌを反映させない場合、修正係数Ｒは全て同じ設定される。更にヒータ温度傾きの偏差の５０％をフィードバックする場合には、修正係数Ｒは０．５に設定される。

In Table 1, the range of 0 <L <1.0 is regarded as appropriate correction, and the correction coefficient R is set large in this range. Further, the range of 1.0 ≦ L is over-corrected, and the correction coefficient R is set small in this range. Further, the range of L <0 is set as inappropriate correction (reverse correction), and the sign of the correction coefficient R is set to “−” in this range. Here, the reason why the correction coefficient R in the range of 1.0 ≦ L is set smaller than the correction coefficient R in the range of 0 <L <1.0 is that the heater temperature gradient T to be automatically corrected next is the actual heater temperature. This is to prevent an overaction that changes beyond the inclination J. The reason why the correction coefficient R in the range of 0 <L <1.0 is set larger than the correction coefficient R in the range of 1.0 ≦ L is that the heater temperature gradient T to be automatically corrected next is the actual heater temperature gradient This is to promptly match J. When the value obtained by subtracting the previously corrected heater temperature gradient from the previous actual heater temperature gradient J is “0”, that is, when the correction amount evaluation value L is “0”, the correction coefficient R needs to be corrected. There is no “0”. When the correction amount evaluation value L is not reflected, the correction coefficients R are all set to the same value. Further, when 50% of the deviation of the heater temperature gradient is fed back, the correction coefficient R is set to 0.5.

  On the other hand, in order to exhibit the above determination function, the correction amount Q of the heater temperature gradient K as a correction candidate is calculated using the following equation (2), and is automatically corrected from now on using the following equation (3). A heater temperature gradient T is calculated.

Q = R × (J−S) = R × K (2)
T = K + Q (3)
The controller 38 automatically corrects the temperature profile of the heater 18 based on the second evaluation function and the determination function, that is, based on the heater temperature gradient T that is automatically corrected next calculated by the equation (3). Composed.

  On the other hand, the controller 38 estimates the starting point of the monotonic increase of the heater temperature during the pulling of the silicon single crystal 11 and causes the automatic correction function of the temperature profile of the heater 18 to be exhibited after exceeding the starting point of the monotonic increase of the heater temperature. Configured. In order to estimate the monotonic increase start point of the heater temperature, as shown in FIG. 7, first, the monotonic decrease end point of the heater temperature is detected, and after detecting the monotonic decrease end point of the heater temperature, the monotonic increase of the heater temperature is detected. Detect the increase start point. Next, since the range of the approximate pulling length of the silicon single crystal 11 from the monotonic decrease end point to the monotonic increase start point can be predicted, calculation processing for estimating the monotonic increase start point after setting the pulling length range Within this range. Further, when the monotonically increasing start point can be estimated, the controller 38 is configured to notify the setter who sets the temperature profile of the heater 18 by display display, sound, or the like. Note that the heater temperature is gradually lowered at the start of the pulling up of the straight body portion 11c of the silicon single crystal 11, and then the heater temperature is gradually raised when the diameter of the silicon single crystal 11 is kept constant. The heater temperature is changed in this way due to the structure of the pulling device.

  On the other hand, the automatic correction function of the temperature profile of the heater 18 is performing a leveling calculation on the temperature profile of the automatically corrected heater 18 so that the temperature profile of the automatically corrected heater 18 maintains continuity. It also has a leveling function. That is, the controller 38 is configured to perform a break-in calculation during pulling up on the automatically corrected temperature profile of the heater 18 so that the temperature profile of the automatically corrected heater 18 is kept continuous. Since the leveling function during the pulling is the same function as the leveling function before the pulling, repeated description is omitted.

  A procedure for pulling up the silicon single crystal 11 using the pulling apparatus for the silicon single crystal 11 configured as described above will be described.

  [1] A procedure for pulling up the silicon single crystal 11 when no unforeseen disturbance occurs during the pulling of the silicon single crystal 11 will be described with reference to the flowchart of FIG. First, the controller 38 selects a pulling device to be set for the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled next. Next, the controller 38 selects past pulling data to be used as reference for setting from the database in the storage medium 39 based on the pulling condition of the pulling device to be set. Then, the controller 38 calculates the weighting factor and the reliability from the pulling conditions of the past pulling data used as reference for setting. At this time, when there are a plurality of pull-up data, the controller 38 calculates the average value of these data. Next, the controller 38 calculates the temperature profile of the heater 18 to be set from the pulling data used as a reference for the weighting factor, reliability, and setting, and then uses the pulling of the silicon single crystal 11 to be set. A correction amount of the temperature profile of the heater 18 is calculated based on one or both of the member and the pulling condition, and this correction amount is added to or subtracted from the temperature profile of the heater 18 to be set. Furthermore, the controller 38 applies a smoothing function before pulling up to the temperature profile of the heater 18 of the silicon single crystal 11 to be set as necessary to determine the final temperature profile of the heater 18.

  If no unforeseen disturbance occurs during the pulling of the silicon single crystal 11, past pulling data of the silicon single crystal 11 contributing to the setting of the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled up next. In the database, the temperature profile of the heater of the silicon single crystal 11 to be pulled next is evaluated from the previous pulling data of the silicon single crystal 11 based on the first evaluation function, and the reliability of the first evaluation function and Based on the weight coefficient, the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled next is corrected before pulling, and the silicon single crystal 11 is pulled up while controlling the heater 18 based on the corrected temperature profile. Thereby, the diameter fluctuation | variation of the silicon single crystal 11 reduces, and the fluctuation | variation of the pulling speed which is an operation amount of the diameter control of the silicon single crystal 11 can be suppressed. As a result, by pulling up the silicon single crystal 11 as set, a high-quality silicon single crystal 11 can be manufactured, and the temperature profile of the heater 18 can be increased in accuracy. Further, since it is not necessary to control the pulling speed of the silicon single crystal 11, the ratio V / G between the pulling speed V of the silicon single crystal 11 and the temperature gradient G in the pulling direction of the silicon single crystal 11 does not vary, and the silicon single crystal 11 The quality of 11 does not vary. Further, the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled up next is evaluated from the pulling data of the silicon single crystal 11 based on the first evaluation function, and the silicon single to be pulled up next based on the first evaluation function. By correcting the temperature profile of the heater 18 of the crystal 11 before pulling, the disturbance expected during the pulling of the silicon single crystal 11 to be pulled next is added to the heating temperature pattern. Even if the trunk portion 11c is pulled up, the diameter does not change.

  Further, the difference between either or both of the constituent member used for pulling up the silicon single crystal 11 and the pulling conditions of the silicon single crystal 11 is converted into the temperature setting value of the heater 18 of the silicon single crystal 11 to be pulled up next. Since the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled up is corrected, the disturbance expected during the next pulling of the silicon single crystal 11 to be pulled up is further added to the heating temperature pattern. The temperature profile can be further improved in accuracy. Further, since the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled next is corrected by the leveling function before the pulling, the temperature profile is corrected, so that the heater is heated in a certain section during the pulling of the silicon single crystal 11. When the inclination of the temperature profile of 18 becomes uneven, the unevenness is relaxed and brought closer to the average value of the inclination of the temperature profile in that section. As a result, large unevenness generated in the temperature profile of the heater 18 before the pulling can be reduced.

  [2] The pulling procedure of the silicon single crystal 11 when an unexpected disturbance occurs during the pulling of the silicon single crystal 11 will be described with reference to the flowcharts of FIGS. First, in the same manner as in the above [1], before pulling up the silicon single crystal 11, the pulling data of the past silicon single crystal 11 contributing to the setting of the temperature profile of the heater 18 of the silicon single crystal 11 is accumulated in the database. Then, the temperature profile of the heater of the silicon single crystal 11 to be pulled next is evaluated based on the first evaluation function based on the previous pulling data of the silicon single crystal 11, and based on the reliability and the weighting factor of the first evaluation function. Next, the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled up is corrected before being pulled up (FIG. 8). Then, if necessary, a smoothing function before pulling is applied to the temperature profile of the heater 18 of the silicon single crystal 11 so as to determine the temperature profile of the final heater 18.

  Then, the controller 38 pulls up the silicon single crystal 11 while controlling the heater 18 based on the temperature profile of the final heater 18. At this time, the controller 38 estimates a monotonically increasing start point of the heater temperature during the pulling of the silicon single crystal 11, and exhibits the function of automatically correcting the temperature profile of the heater 18 after the monotonically increasing start point is exceeded (FIG. 9). ). Thereby, the automatic correction function of the temperature profile of the heater 18 can be exhibited efficiently. After that, during the pulling of the silicon single crystal 11, if an unexpected disturbance occurs due to the occurrence of liquid level vibration due to the earthquake of the silicon melt 14 or the change of the components used in the pulling device, the controller 38, while the silicon single crystal 11 is being pulled, the final temperature profile determined above is further automatically corrected for each predetermined pulling length, and the heater 18 is controlled based on the automatically corrected temperature profile. The silicon single crystal 11 is pulled up. When the temperature profile of the heater is already automatically corrected during the pulling, the controller 38 further automatically corrects this automatically corrected temperature profile for each predetermined pulling length during the pulling of the silicon single crystal 11. The silicon single crystal 11 is pulled up while controlling the heater 18 based on the automatically corrected temperature profile. That is, the controller 38 repeats automatic correction of the temperature profile of the heater 18 based on the second evaluation function and determination function of the automatic correction function of the temperature profile of the heater 18. It is divided into a case where the correction candidate heater temperature gradient K necessary for automatically correcting the temperature profile of the heater 18 is an appropriate correction, an excessive correction, and an inappropriate correction (reverse correction). Next, a method for obtaining the heater temperature gradient T to be corrected will be described (FIGS. 9 to 10).

(a) When the correction candidate heater temperature gradient K is appropriate correction As shown in FIG. 6A, for example, the correct correction is performed when the heater temperature gradient S corrected immediately before is 2.0, for example. The heater temperature gradient J is 1.0, for example, the correction candidate heater temperature gradient K is 1.2, and K is located between S and J. In the case of this proper correction, the correction amount evaluation value L is L = (K−S) / (J−S) = − 0.8 / −1.0 = 0.8 using the equation (1). The correction coefficient R for the correction amount evaluation value L is 0.8 from Table 1. The correction amount Q of the heater temperature gradient is Q = R × K = 0.8 × 1.2 = 0.96 using the equation (2), and the heater temperature gradient T to be corrected next is the equation (3). Using, T = K + Q = 1.2 + 0.96 = 2.16.

(b) When the correction candidate heater temperature gradient K is overcorrection For example, as shown in FIG. 6B, overcorrection is performed when the heater temperature gradient S corrected immediately before is 2.0, for example. The heater temperature gradient J is 1.2, for example, the correction candidate heater temperature gradient K is 1.0, for example, and J is smaller than S and larger than K. In the case of this overcorrection, the correction amount evaluation value L is L = (K−S) / (J−S) = − 1.0 / −0.8 = 1.25 using the equation (1). The correction coefficient R for the correction amount evaluation value L is 0.2 from Table 1. The heater temperature gradient correction amount Q is Q = R × K = 0.2 × 1.0 = 0.2 using the equation (2), and the heater temperature gradient T to be corrected next is the equation (3). Using, T = becomes K + Q = 1.0 + 0.2 = 1.2.

(c) When the heater temperature gradient K of the correction candidate is an inappropriate correction (reverse correction) The incorrect correction (reverse correction) is performed, for example, as shown in FIG. For example, S is 1.2, the actual heater temperature gradient J of this time is 2.0, for example, the correction candidate heater temperature gradient K is 1.0, for example, J is greater than S and K, and K is This is the case when it is smaller than S. In the case of this improper correction (reverse correction), the correction amount evaluation value L is calculated using the equation (1) as follows: L = (K−S) / (J−S) = − 0.2 / 0.8 = − The correction coefficient R for this correction amount evaluation value L is −0.2 from Table 1. The heater temperature gradient correction amount Q is Q = R × K = −0.2 × 1.0 = −0.2 using equation (2), and the heater temperature gradient T to be corrected next is represented by equation (3). ), T = becomes K + Q = 1.0 + (− 0.2) = 0.8.

  Then, the controller 38 automatically corrects the temperature profile of the heater 18 based on the heater temperature gradient T to be automatically corrected next calculated by the above formula (3). As a result, the influence of the disturbance on the diameter of the silicon single crystal 11 generated during the pulling on the heater temperature can be suppressed, so that the high-quality silicon single crystal 11 can be manufactured. Furthermore, the controller 38 uses the leveling function being raised among the automatic correction functions of the temperature profile of the heater 18 to maintain the continuity of the temperature profile of the heater 18 that has been automatically corrected. Then, the leveling calculation is performed (FIG. 10). As a result, the temperature profile of the heater 18 is automatically corrected during the pulling, and even if the inclination of the temperature profile of the heater 18 becomes uneven, the unevenness is relaxed and approaches the average value of the inclination of the temperature profile in that section. . As a result, large unevenness generated in the temperature profile of the heater 18 after automatic correction can be reduced. In the above embodiment, a silicon single crystal is used as the semiconductor single crystal. However, a GaAs single crystal, an InP single crystal, a ZnS single crystal, a ZnSe single crystal, or the like may be used.

  Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
Twenty pulling apparatuses shown in FIG. 1 were prepared, and these pulling apparatuses were designated as first to twentieth pulling apparatuses, and using these pulling apparatuses, a silicon single crystal 11 for manufacturing a silicon wafer having a diameter of 300 mm was pulled. . Specifically, the crucible 13 was filled with a polycrystalline silicon raw material and melted by the heater 18, and the silicon single crystals 11 for manufacturing a silicon wafer having a diameter of 300 mm were pulled up from the silicon melt 14 five times each. These pull-up data were stored in the database of the storage medium 39. Then, before pulling up the next silicon single crystal 11 using the seventh pulling device, the controller 38 determines whether the heater 18 of the silicon single crystal 11 to be pulled up next is based on the reliability and weighting factor of the first evaluation function. The temperature profile was corrected before pulling up. Here, the controller 38 determined the reliability as follows. The temperature gradient deviation of the heater 18 for every pulling length of 5 mm was calculated as an average value, and the temperature gradient deviation of the heater 18 was compared with the first threshold value: ± 0.002 ° C./5 mm, and was evaluated as good. The pass rate that is accepted when the ratio is 80% or more is calculated for every pulling length of 100 mm, and the pass rate is calculated over the entire length of the straight body portion 11c of the silicon single crystal 11, and then stored in the storage medium 39 as a map. Reliability was determined based on the relationship of reliability to acceptance rate.

  Further, the controller 38 compares the pulling data of the silicon single crystal 11 to be pulled next with the pulling data of the silicon single crystal 11 to be fed back to the temperature profile of the heater 18 of the silicon single crystal 11 to be pulled next. The difference between either or both of the constituent members used for pulling up the single crystal 11 and the pulling conditions of the silicon single crystal 11 is converted into the temperature setting value of the heater 18 of the silicon single crystal 11 to be pulled up next, and then pulled. The temperature profile of the heater 18 of the silicon single crystal 11 to be raised was corrected. Further, the controller 38 modified the temperature profile of the next silicon single crystal 11 heater 18 to be pulled up so that the temperature profile of the next silicon single crystal 11 heater 18 was kept continuous. Here, the leveling coefficient before pulling was set to 0.2. Further, the controller pulled the silicon single crystal 11 from the silicon melt 14 in the crucible 13 while controlling the heater 18 based on the heater temperature profile corrected and corrected as described above.

  At this time, the controller 38 estimated the starting point of the monotonic increase of the heater temperature during the pulling of the silicon single crystal 11, and exhibited the function of automatically correcting the temperature profile of the heater 18 after the monotonic increasing start point was exceeded. Thereafter, when an unforeseen disturbance occurs during the pulling of the silicon single crystal 11, the controller 38 determines the final temperature profile determined above for each predetermined pulling length during the pulling of the silicon single crystal 11. The silicon single crystal 11 was pulled up while controlling the heater 18 based on the automatically corrected temperature profile. When the temperature profile of the heater is already automatically corrected during the pulling, the controller 38 further automatically corrects this automatically corrected temperature profile for each predetermined pulling length during the pulling of the silicon single crystal 11. The silicon single crystal 11 was pulled up while controlling the heater 18 based on the automatically corrected temperature profile. That is, the controller 38 repeated automatic correction of the temperature profile of the heater 18 based on the second evaluation function and determination function of the automatic correction function of the temperature profile of the heater 18. In addition, the controller 38 uses the automatically correcting function of the temperature profile of the heater 18 to increase the temperature profile of the automatically corrected heater 18 so that the temperature profile of the automatically corrected heater 18 can be maintained continuously. On the other hand, a break-in calculation was performed. This silicon single crystal was designated as Example 1.

<Comparative Example 1>
The reliability and weighting factor of the first evaluation function are not used, the second evaluation function and the determination function of the heater temperature profile automatic correction function are not used, and the leveling function before pulling and the leveling function during pulling are used A silicon single crystal for producing a silicon wafer having a diameter of 300 mm was pulled up using a tenth pulling device of the same type as the seventh pulling device in Example 1 except that there was no. This silicon single crystal was designated as Comparative Example 1.

<Comparative test 1 and evaluation>
The diameter standardization value for the pulling rate of 20 to 80% of the straight body portion of the silicon single crystal of Example 1 and Comparative Example 1 was determined. The results are shown in FIGS. Here, when the pulling rate when the silicon melt stored in the crucible is all pulled up as a silicon single crystal is 100%, the straight body portion of the silicon single crystal is pulled up within the range of the pulling rate of 20 to 80%. It becomes a range. Further, the diameter standardized value Z _i of the silicon single crystal is expressed as Z _i = x _i / A, where x _i is an actual measurement value of the diameter of the silicon single crystal and A is an average value of the diameter of the silicon single crystal. . The reason for using the diameter standardized value is to facilitate comparison.

  As is apparent from FIGS. 11 and 12, the silicon single crystal of Comparative Example 1 has a large variation in diameter over the entire length, whereas the silicon single crystal of Example 1 has a small variation in diameter over the entire length. I found out. As a result, in the silicon single crystal of Example 1, the variation in the pulling speed operated for diameter control is also reduced, and the ratio V between the pulling speed V of the silicon single crystal and the temperature gradient G in the pulling direction of the silicon single crystal. / G variation was suppressed and quality variation was reduced. That is, crystal defects occurred in the silicon single crystal of Comparative Example 1, whereas no crystal defects were observed in the silicon single crystal of Example 1.

<Comparative test 2 and evaluation>
The temperature setting value pass rate and the standard deviation of the diameter standardized value when the straight body part of the silicon single crystal of Example 1 and Comparative Example 1 was pulled up were determined. Here, the temperature set value pass rate is the pass rate of the temperature gradient deviation of the heater calculated over the entire length of the straight body of the silicon single crystal as described in [Mode for Carrying Out the Invention] of this specification. It is. Specifically, when the heater temperature gradient deviation for each pulling length of 5 mm (minimum unit) is calculated as an average value and the heater temperature gradient deviation is smaller than the first threshold = ± 0.002 ° C./5 mm. It was evaluated as good, and when large, it was evaluated as bad. And the pass rate which makes it pass when the ratio evaluated that it is favorable is 80% or more was computed for every pulling length 100mm, and the pass rate was finally calculated over the straight body part full length of the silicon single crystal. On the other hand, the standard deviation of the diameter standardized value is a value obtained by arithmetically averaging the diameter standardized value obtained in the above <Comparative Test 1 and Evaluation> over the entire length of the straight body of the silicon single crystal. These results are shown in Table 2.

表２から明らかなように、比較例１では、温度設定値合格率が６０％と低かったのに対し、実施例１では、温度設定値合格率が９０％と高くなったことが分かった。また、比較例１では、直径標準化値の標準偏差が０．０００８７と大きかったのに対し、実施例１では、直径標準化値の標準偏差が０．０００５２と小さくなったことが分かった。

As is apparent from Table 2, in Comparative Example 1, the temperature set value pass rate was as low as 60%, whereas in Example 1, the temperature set value pass rate was as high as 90%. In Comparative Example 1, it was found that the standard deviation of the diameter standardized value was as large as 0.00087, whereas in Example 1, the standard deviation of the diameter standardized value was as small as 0.00052.

11 Silicon single crystal (semiconductor single crystal)
13 Crucible 14 Silicon melt (semiconductor melt)
18 Heater

Claims (8)

The semiconductor raw material supplied to the crucible of the semiconductor single crystal pulling device is melted by a heater, the semiconductor melt is stored in the crucible, and the heater is controlled based on a temperature profile set in advance in the pulling device. In the method for pulling up a semiconductor single crystal that pulls up the semiconductor single crystal from a semiconductor melt in a crucible,
Accumulating in the database the pulling data of past semiconductor single crystals that contribute to the setting of the temperature profile of the heater;
A step of evaluating a temperature profile of a silicon single crystal heater to be pulled up next from pulling data of a past semiconductor single crystal accumulated in the database based on a first evaluation function;
Correcting the temperature profile of the next semiconductor single crystal heater to be raised based on the first evaluation function before pulling;
Pulling the semiconductor single crystal from the semiconductor melt in the crucible while controlling the heater based on the modified temperature profile,
During the pulling of the semiconductor single crystal, the corrected temperature profile is further automatically corrected for each predetermined pulling length, and the heater is controlled based on the automatically corrected temperature profile, and the semiconductor melt in the crucible is Pull up semiconductor single crystals ,
The first evaluation function is a reliability determined from the proximity of the set value and the actual value of the temperature profile of the past semiconductor single crystal heater fed back to the temperature profile of the next semiconductor single crystal heater to be pulled up And the set pulling condition of the next semiconductor single crystal to be pulled up and the actual pulling condition of the pulling data of the past semiconductor single crystal fed back to the temperature profile of the heater of the next single semiconductor to be pulled up A weighting factor determined from the proximity of the set pulling condition and the actual pulling condition when
A method for pulling up a semiconductor single crystal, comprising: correcting a temperature profile of a heater of the next semiconductor single crystal to be pulled up based on the reliability and the weighting factor before pulling up.   The automatic correction function of the temperature profile of the heater is the difference between the heater temperature gradient automatically corrected immediately before the semiconductor single crystal is pulled up and the heater temperature gradient based on the heater temperature measured immediately before and the heater temperature measured this time A second evaluation function that evaluates a candidate heater temperature gradient that is to be automatically corrected next, and a determination function that determines a heater temperature gradient that is to be automatically corrected next based on a result obtained by the second evaluation function. A method for pulling a semiconductor single crystal according to claim 1. Said guess monotonicity starting point of the heater temperature at the pulling in of the semiconductor single crystal, according to claim 1 or 2 autocorrect temperature profile of the heater can be exerted from beyond the monotonous increase start point of the heater temperature The semiconductor single crystal pulling method described. The automatic correction function of the heater temperature profile further has a leveling function for performing a smoothing calculation on the temperature profile of the automatically corrected heater so that the temperature profile of the automatically corrected heater is kept continuous. The method for pulling a semiconductor single crystal according to claim 1. The semiconductor raw material supplied to the crucible is melted by the heater, the semiconductor melt is stored in the crucible, and the controller controls the heater based on a preset temperature profile while the semiconductor melt is stored in the crucible. In a semiconductor single crystal pulling apparatus configured to pull a crystal,
The controller is
Accumulating past semiconductor single crystal pulling data that contributes to the setting of the temperature profile of the heater in a database;
Based on the first evaluation function, the temperature profile of the next semiconductor single crystal heater to be pulled up from the past semiconductor single crystal pull-up data stored in the database,
The first evaluation function is a reliability determined from the proximity of the set value and the actual value of the temperature profile of the past semiconductor single crystal heater fed back to the temperature profile of the next semiconductor single crystal heater to be pulled up And the set pulling condition of the next semiconductor single crystal to be pulled up and the actual pulling condition of the pulling data of the past semiconductor single crystal fed back to the temperature profile of the heater of the next single semiconductor to be pulled up A weighting factor determined from the proximity of the set pulling condition and the actual pulling condition when
Based on the reliability and the weighting factor , the temperature profile of the next semiconductor single crystal heater to be pulled up is corrected before pulling up,
Pulling up the semiconductor single crystal from the semiconductor melt in the crucible while controlling the heater based on this modified temperature profile,
During the pulling of the semiconductor single crystal, the corrected temperature profile is further automatically corrected for each predetermined pulling length, and the heater is controlled based on the automatically corrected temperature profile, and the semiconductor melt in the crucible is An apparatus for pulling a semiconductor single crystal, characterized by being configured to pull the semiconductor single crystal. The automatic correction function of the heater temperature profile includes a heater temperature gradient automatically corrected immediately before the semiconductor single crystal is being pulled up, a heater temperature gradient measured immediately before, and a heater temperature gradient based on the heater temperature measured this time. A second evaluation function for evaluating a candidate heater temperature gradient to be automatically corrected based on the difference; and a determination function for determining the heater temperature gradient based on a result obtained by the second evaluation function;
6. The semiconductor single crystal pulling apparatus according to claim 5 , wherein the controller is configured to automatically correct a temperature profile of the heater based on the second evaluation function and the determination function. The controller infers a monotonically increasing start point of the heater temperature during pulling of the semiconductor single crystal, and exhibits an automatic correction function of the heater temperature profile after the heater temperature monotonically increasing start point is exceeded. The semiconductor single crystal pulling apparatus according to claim 5 or 6 , wherein the pulling apparatus is a semiconductor single crystal. The controller, with respect to the temperature profile of the heater in which the temperature profile of the heater the corrected automatically has the automatic correction so as to keep the continuity, leveling 5 claims is configured to perform calculations to 7 any one The semiconductor single crystal pulling apparatus according to 1 .

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