JP2726773B2 - Silicon single crystal pulling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pulling a single crystal which can be suitably used especially for pulling a silicon single crystal by using the Czochralski method.

[0002]

2. Description of the Related Art As a method for producing a single crystal such as silicon, a single crystal raw material contained in a crucible is melted, and a seed crystal is brought into contact with the surface of the melt. A so-called Czochralski method, in which a seed crystal is raised while rotating in the opposite direction to pull up and grow a single crystal, is generally employed. Conventionally, when producing a single crystal in this manner, among various operating conditions for operating the pulling furnace, the pulling speed (that is, the seed raising speed) and the heater temperature are automatically recorded on a recording sheet. The operator visually checked the conditions against the standard set values.

In the silicon single crystal manufactured as described above, there are point defects, fluctuations in oxygen concentration, fluctuations in carbon concentration, and the like that occur when the single crystal is solidified.
It is known that these fluctuations are caused mainly by fluctuations in conditions at the time of pulling a single crystal, but the allowable range of these fluctuations cannot be determined unconditionally, and they are manufactured using this single crystal. Since different thermal histories are traced depending on the semiconductor manufacturing conditions, oxygen precipitation must be within an appropriate range until the final process, and the strength of the wafer must be maintained. Is presented. In addition, utilizing the generation of oxygen precipitation defects by heat treatment, harmful metal atoms are attracted to these defects and fixed.
G (Intrinsic Gettering) technology is also actively used, and in this case, a crystal having a high oxygen concentration is generally used.
The distribution of this oxygen concentration in the wafer also becomes a problem, and the difference in concentration between the central part and the peripheral part causes non-uniform oxygen precipitation, which lowers the yield of semiconductors and causes large warpage, which may cause problems in semiconductor manufacturing equipment and transfer equipment. It is also known that production may no longer be possible. In addition, a region in which a large number of stacking faults (Oxidation Stacking Fault) caused by oxygen generated during oxidation heat treatment in the manufacture of a specific semiconductor integrated circuit (hereinafter referred to as an OSF generation region) is present in the single crystal. There is. When a wafer collected from such an OSF generation region is used, an OSF is generated in a heat treatment process of manufacturing a semiconductor integrated circuit, resulting in a defect.

For this reason, in order to supply a wafer which fits a specific semiconductor manufacturing condition, it is also possible to manufacture a semiconductor with several kinds of certified samples of the pulling condition, and then to pull up the wafer under the condition of the best product yield. It is common practice in the manufacture of highly integrated semiconductors.

Further, under certain specific semiconductor manufacturing conditions, O
In order to prevent frequent occurrence of SF, heat treatment is performed under conditions assumed to be the most dangerous, and OSF density after heat treatment is negotiated. For this reason, after slicing the single crystal so that the abnormal OSF generation region does not flow to the subsequent process, a sample is extracted from the sliced crystal, and subjected to an oxidation heat treatment and an etching inspection under conditions agreed with the customer. , Whether or not the OSF occurrence area exists, and if the OSF occurrence area exists,
Non-conforming products, including those before and after that. Further, in order to examine the IG effect, a simulation heat treatment for periodically reproducing a thermal history of a specific integrated circuit was performed to check whether or not there was a change in conditions.

[0006]

In the conventional single crystal pulling method, not all conditions at the time of pulling a single crystal are recorded, and even if an operation recording mode is determined, recording leakage and recording error can be avoided. However, it has been difficult to always accurately determine whether each part of the single crystal thus obtained is a normal part or a part that does not conform to the customer's request. Further, as described above, even if the quality inspection is performed by the sampling inspection, a sufficiently satisfactory inspection result cannot be obtained yet, so that improvement is required.

The present invention has been made in view of the above circumstances, and provides a single crystal pulling method capable of reliably grasping a crystal lot portion that does not conform to the manufacturing conditions of a customer and improving the reliability and stability of quality. With the goal.

[0008]

A silicon single crystal pulling method of the present invention According to an aspect of the plurality of silicon is grown respectively a silicon single crystal from the pulling machine silicon melt contained in a crucible of the Czochralski method single crystal In the lifting method, each of the plurality of lifting machines is
Connected to the primary computer provided for each lifting machine,
The primary computers are each one secondary computer
Primary computer with a communication line is connected will in, is stored temporarily in the primary computer <br/> chromatography data with automatic detection at predetermined time intervals the data of pulling conditions, and automatically detects the start time of the pulling process to To temporarily memorize,
And is temporarily stored in the primary computer detects the pulling direction of the position of the shoulder steps starting crucible silicon charge amount and the furnace gas leakage amount and the single crystal in the crucible during silicon melting step starts, the two Next
Computers are measured at each lifting machine every predetermined time.
Data request to send the stored data
It sends a signal to the primary computer, each primary computer <br/> over data, upon receiving the data request signals, the real so far
Statistical processing of the measured and stored data
And the secondary computer is statistically processed and
The data transmitted from the primary computer is compared with the preliminarily stored permissible ranges of these data, and the data out of the permissible range is output as pull-out nonconformity information. To detect parts outside the lifting conditions of
The method is characterized in that data for each lifting is stored in the secondary computer.

[0009]

According to the method for pulling a silicon single crystal of the present invention, the operating conditions are automatically detected, so that omissions or omissions by the operator can be eliminated, and the obtained measurement results can be compared with standard setting values. By computer processing, a portion of the single crystal outside the condition based on an abnormality in the operating condition that has not been recorded in the related art can be grasped simultaneously with the completion of the pulling. Then, in the slicing process, which is a process after the lifting, the incompatible portion can be immediately eliminated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for pulling a silicon single crystal according to the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1 and 2 show an example of an apparatus for carrying out a silicon single crystal pulling method of the present invention. In the figure, reference numeral 1 denotes a pulling machine main body constituting the apparatus. As shown in FIG. 2, the lifting machine main body 1 is provided with a quartz crucible 2 at a substantially central portion of a furnace 5. The quartz crucible 2 is attached via a graphite susceptor 3 to a vertically movable and rotatable lower shaft 4. Around the quartz crucible 2, a heater 7 for controlling the temperature of the silicon melt 6 in the quartz crucible 2 is provided. Above the quartz crucible 2, a wire 11 for holding and pulling up the single crystal 9 is hung up and down and rotatably. When the silicon single crystal 9 is pulled by the pulling machine main body 1, first, the air in the furnace 5 is sufficiently replaced with argon gas, and the raw material previously stored in the quartz crucible 2 is melted by the heater 7. The wire 11 is moved down and a seed crystal (seed) is formed in the melted silicon melt 6.
Then, while rotating the quartz crucible 2 and the seed crystal in directions opposite to each other, the wire 11 is raised to grow the single crystal 9.

As shown in FIG. 1, a lifting machine microcomputer (primary computer) 13 of an operation status monitoring system is connected to the lifting machine body 1, respectively. The lifting machine microcomputer 13 includes a sensor for a mechanism for driving the wire 11 of the body 1 of the lifting machine, a sensor for a mechanism for driving the crucible 2, a heater 7, a furnace thermometer (not shown), a furnace pressure gauge, an argon flow meter, and the like. Various sensors for detecting conditions while the single crystal is being pulled are connected. Further, a mechanism for automatically detecting the start time of each step of the lifting process performed by the lifting machine main body 1 is connected to the lifting machine microcomputer 13. The data sent to the microcomputer 13 is temporarily stored in the microcomputer 13. The microcomputer 13 is connected to a minicomputer (secondary computer) 15 via a communication line 14. The data collected by the microcomputer 13 is sent to the mini-computer 15 via the communication line 14. The mini-computer 15 is connected via the communication line 14 to a printer 16 for outputting pull-out incompatibility information and a terminal 17 for displaying downloaded data. Further, the minicomputer 15 is connected to a magneto-optical disk 18 for storing the downloaded data.

Next, an embodiment of the method for pulling a silicon single crystal of the present invention performed by this apparatus will be described with reference to the flowchart of FIG. In the following description, Sn
Indicates the n-th step in the flowchart. In this single crystal pulling method, when the production of a single crystal is started, measured data of pulling conditions shown in the following group A measured at regular time intervals by various sensors provided in the pulling machine main body 1 and the following group B The data of the start time of each step at the time of raising is sent to the microcomputer 13. Data such as the amount of silicon charged in the crucible at the start of the silicon dissolution process, the amount of gas leaked in the furnace, the position of the crucible at the start of the shoulder process (position in the pulling direction), and the like are also sent to the microcomputer 13 (S1). Group A Group B Seed rise speed Vacuum process Crucible rise speed Melt process Seed rotation speed Seed process Crucible rotation speed Shoulder process Heater temperature Straight body process Furnace pressure Bottom process Argon flow rate cooling process Process to perform manual operation for raising and lowering seed and crucible Seed and Step of Performing Manual Operation on Rotation of Crucible Each microcomputer 13 temporarily stores the above data (S
2). On the other hand, each microcomputer 13
A signal requesting data is sent at 10-minute intervals (S3).
5 is sent to the data (S4). These data are stored on the magneto-optical disk 18 (S5). For example, the allowable variation rate of each parameter is input to the minicomputer 15 on the screen shown in FIG. 4, and the stored data determines whether each part of the manufactured single crystal can be shipped. At this time, the data is compared with these allowable ranges and it is determined whether or not they fall within the allowable range (S6). If it is not within the allowable range, the part is determined to be unsuitable for shipping, and if it is within the allowable range, the part is determined to be suitable for shipping.

On the other hand, at the terminal 17, each obtained crystal is shown in FIG.
Data (maximum, minimum, average)
Value, median, standard deviation) can be displayed in a graph. The illustrated graph shows the relationship between the seed raising speed and the single crystal pulling length. In the graph, reference numerals 20 and 21 denote lines indicating the upper and lower limits of the allowable range of the seed raising speed. The seed raising speed is displayed by data processing at 10 mm intervals in the straight body portion of the single crystal. That is, the maximum, minimum, average, median, and standard deviation of the seed rise speed when the part is pulled up every 10 mm of the pulling length.
(Data downloaded from the microcomputer 13 ). In this graph, portions indicated by D, E, and F are portions where the maximum value and the minimum value are outside the allowable range. Such a place where the seed raising speed is out of the allowable range can also be confirmed by an output from the printer 16 as shown in the following table.

[0015]

[Table 1]

According to this operation status monitoring system,
The time at which each step during single crystal pulling was started is shown in FIG.
Can be displayed and confirmed on the terminal 17 as shown in FIG.

According to this single crystal pulling method, the operating conditions during the production of the single crystal are automatically detected, so that the omission or mistake of the entry by the operator can be eliminated, and the comparison between the actually measured data and the standard set value can be performed. By performing the computer processing, a portion of the single crystal outside the condition based on the abnormality of the operating condition which has not been recorded in the related art can be grasped simultaneously with the completion of the pulling.

For example, when the pulling speed (seed rising speed) is abnormal as shown in FIG. 7A, an OSF generation region 24 is formed in the single crystal as shown in FIG. 7B. I can understand that. Seed rotation speed (SR)
When the ratio of the crucible rotation speed (CR) shows an abnormal value, the in-plane distribution ratio of the oxygen concentration ((central oxygen concentration−peripheral oxygen concentration) ÷ central oxygen concentration; Hereinafter, it can be known that ORG) is out of the allowable range.

In the slicing step, which is a post-pulling-up step, the parts out of these conditions are immediately excluded, so that the supply of an unsuitable part to the subsequent step can be prevented. Therefore, according to the single crystal pulling method of this embodiment, a non-conforming part or a crystal lot that does not conform to the production conditions of the customer can be reliably grasped, and the reliability and stability of quality can be improved.

[0020]

A silicon single crystal pulling method of the present invention as described in the foregoing, the silicon single growing plurality of pulling machine by the Czochralski method from the contained silicon melt in the crucible silicon single crystal, respectively In the crystal pulling method, the plurality of pullers are each
Connected to the primary computer provided for each lifting machine.
And each primary computer has one secondary computer
Computer, and automatically detects the data of the pulling condition at a predetermined time interval, temporarily stores the data in the primary computer, and sets the start time of the pulling process. Automatic detection and temporary storage in the primary computer, and detection of the amount of silicon charged in the crucible at the start of the silicon melting process, the amount of gas leak in the furnace, and the position of the single crystal in the crucible pulling direction at the start of the shoulder process It is temporarily stored in the primary computer as well as the
The secondary computer is located at each lifting machine every predetermined time.
Requesting that the measured and stored data be sent
It sends a data request signal to the primary computer, the respective primary co <br/> computer, upon receiving the data request signal, Sorema
Statistical processing of the data measured and stored in
Computer and the secondary computer is statistically processed.
Then, the data transmitted from the primary computer is compared with a previously stored allowable range of the data, and data out of the allowable range is output as pull-out nonconformity information. The method is characterized in that a portion of the crystal outside the pulling conditions can be detected, and data for each pulling is stored in the secondary computer. According to such a method for pulling a silicon single crystal of the present invention, it is possible to eliminate entry omission and entry mistake of an operator,
By performing computer processing on the comparison between the measured data and the standard set value, it becomes possible to grasp the unconventional portion of the single crystal based on the abnormality of the operating condition which has not been recorded in the past and at the same time when the pulling is completed. Then, the non-conforming part can be immediately excluded in the slicing step which is a post-pulling-up step, and it can be prevented that the non-conforming part is supplied to the subsequent step. Therefore, according to the single crystal pulling method of this embodiment, crystal lots that do not conform to the external conditions or the manufacturing conditions of the customer can be reliably grasped, and the reliability and stability of quality can be improved.

Also, by employing the method of the present invention,
In addition to being able to more accurately grasp the situation of the single crystal pulling site in the central control room, it is possible to remotely monitor for errors in the pulling operation execution procedure and malfunctions and prompt the operator to quickly correct the error. Even if it is determined that the product is suitable for shipment without displaying any abnormalities, but abnormalities such as a drastic decrease in the yield or the inability to continue the process occur in the subsequent semiconductor manufacturing process, data can be immediately collected even after a considerable amount of time has elapsed. The detailed history of pulling can be re-checked by calling up the screen, and crystal lots pulled under the same conditions can be specified and eliminated during the manufacturing process. In addition, if there are differences between crystal lots under the same semiconductor manufacturing conditions, comparing these data makes it possible to newly discover that previously overlooked operations are related to the quality of single crystals. The effect of the present invention is extremely large, for example, the crystal pulling conditions can be set so as to be optimized for various kinds of semiconductor manufacturing conditions.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an operation status monitoring system of an apparatus for implementing one embodiment of a silicon single crystal pulling method of the present invention.

FIG. 2 is a cross-sectional view showing a pulling machine main body constituting an apparatus for carrying out one embodiment of the silicon single crystal pulling method of the present invention.

FIG. 3 is a flowchart showing one embodiment of a method for pulling a silicon single crystal of the present invention.

FIG. 4 is a diagram showing a screen for inputting an allowable variation rate of each parameter.

FIG. 5 is a graph in which a vertical axis indicates a seed raising speed and a horizontal axis indicates a pulling length.

FIG. 6 is a diagram showing a screen display of a driving situation.

FIG. 7 is a schematic diagram for explaining a relationship between a lifting speed and formation of an OSF generation region.

FIG. 8 is a schematic diagram for explaining a relationship between a ratio between a seed rotation speed and a crucible rotation speed and ORG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Puller main body 9 Single crystal 13 Microcomputer 15 Minicomputer 18 Magneto-optical disk

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-108125 (JP, A) JP-A-63-286668 (JP, A) JP-A-1-307679 (JP, A)

Claims (1)

(57) [Claims] 1. A plurality of silicon single crystal pulling method for growing each silicon single crystal by the Czochralski method from pulling machine silicon melt contained in a crucible of the plurality of pulling machine, each pulling each Set for each machine
Each primary computer connected to the primary computer
Are connected to one secondary computer via a communication line
Is made by, is temporarily stored in the primary computer as well as automatic detection at predetermined time intervals the data of pulling conditions, and is temporarily stored in the primary computer <br/> Ta with automatically detects the start time of the pulling process, and one primary computer detects the silicon melting step at the start charge amount and furnace gas leakage quantity and pulling direction of the position of the crucible at the shoulder steps beginning of monocrystalline silicon in the crucible
Time is stored, the secondary computer, each pulling device at every predetermined time
To send measured and stored data at
Sending a data request signal to each primary computer, wherein each primary computer receives the data request signal
Statistical processing of the data measured and stored up to that point
And sends it to the secondary computer, which is statistically processed and sent to the primary computer.
The data sent from the data is compared with the pre-stored permissible ranges of these data, and the data out of the permissible range is output as pull-up non-conformity information. A portion outside the pulling condition of the silicon single crystal can be detected, and data of each pulling is stored in the secondary computer.