JPH06279177A - Method and device for controlling pulling of single crystal - Google Patents

Abstract

PURPOSE:To control the diameter of a single crystal with high precision. CONSTITUTION:A pulled single crystal is vibrated with a prescribed period for a prescribed distance, the variation of the weight of the single crystal caused by the vibration is detected and the single crystal is pulled so that the variation is kept always constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulling control method and apparatus for a single crystal body which is a material for a single crystal substrate for manufacturing a semiconductor circuit.

[0002]

2. Description of the Related Art In the field of semiconductor manufacturing, the Czochralski method has been generally used as a method for growing a silicon single crystal. An example of an apparatus using this method is an apparatus as shown in FIG. 4 (Japanese Patent Laid-Open No. 64-72984).

An apparatus 1 shown in FIG. 4 has a chamber 2 mainly composed of a heating chamber 2a containing a structure for melting silicon and a pulling chamber 2b containing a silicon single crystal S to be pulled, In the heating chamber 2a, a crucible 5 and a heater 6 arranged so as to mainly surround the side surface of the crucible 5 are provided.
The crucible 5 contains the silicon melted by the heater 6. The crucible 5 is connected to a driving device (not shown) by a rotary shaft 4, and is rotated at a predetermined speed by the driving device. Usually, the crucible 5 is composed of a quartz crucible 5a and a graphite crucible 5b for protecting it.

On the other hand, the pull-up chamber 2b has a ceiling portion 3a which closes the opening of the heating chamber 2a and the ceiling portion 3a.
Is located in the central portion of and is mainly composed of an accommodating portion 3b for accommodating the growing silicon single crystal S. Further, inside the pulling chamber 2b, a pulling wire 7 penetrating through the top wall is provided, and a chuck 9 for holding a seed crystal 8 is provided at the lower end of the pulling wire 7. The upper end side of the pulling wire 7 is the wire hoisting machine 1
It is wound around 0, and the silicon crystal body S being grown is pulled up at a predetermined speed. Although the heat insulating member 11 is provided on the side of the heating chamber 2a of the heating heater 6 shown in the figure, this is to prevent heat from the heating heater 6 from escaping to the outside of the heating chamber 2a.

Inside the chamber 2, there is a pulling chamber 2b.
Argon gas is introduced from the gas introduction port 12 formed in the heating chamber 2a from the gas introduction port 12 through the inside of the housing portion 3b as shown in the drawing. And is discharged from the gas discharge port 13. The argon gas is circulated in this way in order to rapidly cool the silicon single crystal S that is being grown, and in SiO ₂ generated in the chamber 2 as the silicon is melted.
This is to prevent gas from being mixed into the silicon melt.

At a part of the ceiling portion 3a of the pulling chamber 2b, a state of a solid-liquid interface which is a boundary surface between the melt melted in the crucible 5 and the outer peripheral surface of the silicon single crystal body S pulled from here. A peephole 26 for observing is displayed. A camera 27 for observing the diameter and for observing the state of the solid-liquid interface is installed in the peephole 26 as shown in the drawing, and a silicon single crystal having a desired diameter is pulled up based on a signal from the camera 27. Thus, the lifting speed of the wire hoisting machine 10 is adjusted.

Further, in controlling the diameter of the ingot, in addition to the above technique, a weight measuring machine for measuring the weight of the silicon single crystal body S via the wire 7 is provided in the wire hoisting machine 10 and the weight measuring machine detects the weight. In some cases, the pulling rate of the wire winding machine 10 is adjusted so that the silicon single crystal body having a desired diameter is pulled up based on the amount of increase in the weight.

[0008]

However, in the conventional apparatus for producing a single crystal body having such a structure, the diameter of the silicon single crystal body is determined by the image pickup signal from the camera or the weight measurement as described above. The accuracy was not always satisfactory because it was based on the weight detected by the machine.

That is, when using a camera, it is not easy to accurately capture the boundary between the solid-liquid interface between the ingot and the melt, and when using a weight measuring machine, the wire hoisting machine 10 itself is not easily detected. It is required for diameter control because it is affected by vibration and dark ground vibration.
There is a problem that it is difficult to measure the weight change of ^-5 orders.

The present invention has been made in order to solve such a conventional problem, and an accurate diameter control can be performed by measuring a weight change amount while vibrating a silicon single crystal body being pulled. An object of the present invention is to provide a method for pulling a single crystal and a device therefor.

[0011]

The present invention for achieving the above object is a method for controlling pulling of a single crystal body for pulling a single crystal body having a desired diameter from a melt contained in a crucible, the method comprising: The single crystal body to be pulled is vibrated at a predetermined distance for a predetermined period, the weight change amount of the single crystal body caused by the vibration is detected, and the single crystal body is pulled so that the weight change amount is always constant. It is characterized by.

Further, a pulling means for pulling a single crystal body grown from a melt contained in the crucible, a vibrating means for vertically vibrating the single crystal body, and a vibrating means for vibrating the single crystal body. Weight change amount detecting means for detecting the weight change amount of the single crystal, and control means for controlling the drive of the pulling means so that the weight change amount detected by the weight change amount detecting means becomes constant. It is characterized by.

[0013]

The method and apparatus for pulling a single crystal body according to the present invention having the above-described structure will function as follows. When the pulled single crystal body is vibrated at a predetermined distance and at a predetermined cycle, the weight detected changes in a cycle synchronized with this vibration. When the diameter is the same, the change range of the weight that changes according to this vibration is the same,
When the diameter increases, this fluctuation range naturally increases. Therefore, if the pulling amount of the single crystal body is adjusted so that the detected fluctuation width is always constant, an ingot having the same diameter can be obtained over the entire length.

On the other hand, the vibrating means vibrates the single crystal body growing from the melt so as to vertically vibrate. The weight change amount detecting means detects the weight change of the single crystal body vibrated by the vibrating means, and at the same time, detects the weight change amount. The control means controls the drive of the pulling means so that the detected amount of change in weight becomes a constant value, and by this control, the pulling means pulls up the single crystal body so that it has a constant diameter.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a single crystal pulling apparatus according to the present invention. This drawing shows only the part related to the gist of the present invention, and the structure of the other parts related to the chamber is exactly the same as the structure shown in FIG. Is omitted.

In this figure, a detailed internal structure of the wire winding machine 10 and a detailed structure of a control device for processing signals from electric components provided therein are drawn. Pulling wire 7 for pulling the growing single crystal
Is wound around a take-up reel 41 via a pulley 40. The take-up reel 41 is driven by a motor 42.

A shaker 43 is mechanically connected to the pulley 40 as a vibrating means for vibrating the pulley 40. The load cell 44 for detecting the suspended weight is further connected to the shaker 43.
Are mechanically connected. Therefore, the growing silicon single crystal body suspended by the pulling wire 7 is moved up and down in the pulling direction and the pulling direction by the vibrator 43 at a predetermined frequency.
Then, the suspended weight at this time is detected by the load cell 44.

On the other hand, the oscillating power source 50 drives the oscillating device 43, and the oscillating device 43 oscillates at a predetermined frequency and a predetermined amplitude according to the oscillating signal output from the oscillating power source 50. To do. The diameter calculator 51 calculates the current diameter of the silicon single crystal body based on the weight signal from the load cell 44. The weight signal from the load cell 44 is output to the diameter calculator 51, and the vibration power source 50 outputs the weight signal. It is analyzed based on the output excitation frequency signal and regenerated into the diameter signal of the silicon single crystal body. The comparator 52 compares the diameter signal input thereto with the set diameter setting value, and outputs a pull-up signal when the calculated diameter signal becomes larger than the set value. The motor driver 53 drives the motor 42, and drives the motor 42 only when the pull-up signal is output from the comparator 52 to pull up the silicon single crystal.

The apparatus of the present invention has the above-described configuration. Next, the operation of the apparatus will be described with reference to the flowchart of FIG. When this device operates, first, the vibration power supply 50 gives a vibration signal to the vibration generator 43, and the vibration generator 4
3 vibrates in synchronization with this signal. The vibration of the vibrator 43 is transmitted to the pulling wire 7 via the pulley 40, and as a result, the silicon single crystal body being grown is vertically vibrated. It is recommended that this vibration frequency be about 100 Hz. It is sufficient that the amplitude of this vibration is about 100 μm. Therefore, when such a vibration is applied, the silicon single crystal body is vertically moved by ΔL in a predetermined cycle as shown in FIG. The vibrator 43 is, for example, a piezoelectric element (S1). The load cell 44 is the vibrator 43,
The weight of the silicon single crystal body including the pulley 40 and the pulling wire 7 is output as a weight signal. Since the silicon single crystal is vibrated as described above by the vibrator 43, this weight signal is synchronized with its vibration frequency.
The signal has a sinusoidal waveform as shown in the uppermost graph of (B). This signal is input to the diameter calculator 51 (S
2). The diameter calculator 51 is input within a predetermined time period as shown in FIG.
(B) The upper limit value and the lower limit value of the signal as shown in the uppermost part are detected, and the diameter of the silicon single crystal body being pulled up is calculated based on this signal. The detection of the upper limit value and the lower limit value is performed based on the vibration frequency signal output from the vibration power supply 50. This excitation frequency signal is a signal with a small output having the same frequency as the excitation signal output to the exciter 43. In addition, this diameter calculator 5
Reference numeral 1 indicates that the weight signal including the input high frequency signal is waveform-shaped and converted into a smooth sinusoidal signal as shown in the middle part of FIG. 3 (B), and the diameter is calculated based on the converted signal. (S3, S4).

The diameter calculator 51 detects the upper limit value and the lower limit value of the weight signal input within the fixed time,
The amount of weight change due to the vibration of the silicon single crystal is detected.
That is, of the weight of the silicon single crystal body detected by the load cell 44, the degree of change in weight due to vibration is calculated. If the diameter of the growing silicon single crystal does not change, the value of the diameter signal calculated and output by the diameter calculator 51 is unchanged. As shown in FIG. 3 (A), the silicon single crystal body vibrates up and down by ΔL when being excited, but if the diameter of the silicon single crystal body is unchanged, the silicon single crystal body moves up by ΔL. It is considered that the amount of increase in the detected weight when pulled up is always constant. The present invention attempts to control the diameter based on this idea (S5). Next, the comparator 52 inputs the diameter signal d (in other words, the amount of weight change) output from the diameter calculator 51 and the preset diameter set value D (the amount of weight change at the desired diameter). And this diameter signal d
It is determined whether the value of is larger than the diameter setting value D (S6, S7). In this determination, if d ≦ D, the process returns to step 1 and the same processing as above is repeated. If d> D, the signal for pulling up the silicon single crystal (ingot) is the comparator 5
2 to the motor driver 53. Upon receiving this signal, the motor driver 53 drives the motor 42,
Pull up the silicon single crystal. This raising is performed until the diameter signal d matches the diameter setting value D (S
8).

As described above, in the present invention, the silicon single crystal body is vibrated at a constant vibration period, and the diameter is controlled based on the deviation of the weight change accompanying the vibration. Therefore, this vibration has a higher frequency than the dark vibration that the device receives. Therefore, when performing diameter control, it is possible to achieve extremely high precision diameter control without being affected by such vibration. You will be able to

[0022]

As described above, according to the present invention, the diameter of a silicon single crystal can be controlled with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a pulling control apparatus for a single crystal body that realizes the method of the present invention.

FIG. 2 is a flowchart showing the operation of the apparatus shown in FIG.

FIG. 3 is a diagram for explaining the operation of the method and apparatus of the present invention.

FIG. 4 is a schematic configuration diagram of a conventional single crystal pulling control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Single-crystal manufacturing apparatus 2 ... Chamber 2a ... Heating chamber 2b ... Pulling chamber 5 ... Crucible 6 ... Heating heater 7 ... Pulling wire (pulling means) 8 ... Seed crystal 42 ... Motor (pulling means) 43 ... Exciter (Vibration means) 44 ... Load cell (weight change amount detection means) 51 ... Diameter calculator (weight change amount detection means) 52 ... Comparator (control means) 53 ... Motor driver (control means)

Claims (2)

[Claims] 1. A method for controlling the pulling of a single crystal having a desired diameter from a melt contained in a crucible, which comprises vibrating the pulled single crystal at a predetermined distance for a predetermined period. A method for controlling pulling up of a single crystal body, which comprises detecting a weight change amount of the single crystal body caused by the vibration and pulling up the single crystal body so that the weight change amount is always constant. 2. A pulling means for pulling a single crystal body growing from a melt contained in a crucible, a vibrating means for vertically vibrating the single crystal body, and a vibrating means for vibrating the single crystal body. Weight change amount detecting means for detecting the weight change amount of the single crystal, and control means for controlling the drive of the pulling means so that the weight change amount detected by the weight change amount detecting means becomes constant. A pulling control device for a single crystal body characterized by: