JPS627694A - Device for controlling crystal pulling velocity - Google Patents

Abstract

PURPOSE:To control the crystal pulling velocity with high accuracy and to grow a crystal of constant length in a prescribed time by storing plural constants of the pulse trains of a pulse motor corresponding to the set crystal pulling velocity and providing a circuit for calculating the constants. CONSTITUTION:The pulse signals PS of a pulse oscillator 25 connected to a pulse motor 22 through a driver circuit 24 are supplied to a dividing circuit 27 and divided and a divided pulse time interval signal BP is sent to an arithmetic control circuit 28 and a counter circuit 29. Whether the counted results from the counter circuit 29 are in the specified range or not is judged by the arithmetic control circuit 28, the compared value and the plural dividing constants determined by the dividing circuit 27 are stored, calculation is carried out on the basis of the data and the data for displaying the velocity is sent to a display device 33. Besides, a switching command BK is sent to the dividing circuit 27. The pulse signals PS sent out from the pulse oscillator 25 are divided by the newly specified dividing ratio and the crystal pulling velocity is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a crystal pulling speed control device in an apparatus for pulling crystals used for electronic parts and the like.

[Technical background of the invention]

The required single crystals used in electronic components are usually produced by immersing a seed crystal in the liquid surface of a raw material melt that has been heated to a predetermined temperature and then being pulled up at a predetermined speed. In order to form this single crystal to a predetermined diameter and length, it is necessary to precisely control the temperature of the raw material melt and the crystal pulling speed. Power supply to the high frequency heating coil placed around the
DC motor ■ which supplies high frequency power to the melt in the crucible ω to control the temperature at which a crystal of the required diameter can be obtained, and also drives the support part ■ which supports the seed crystal 0.
This is done by giving a command from an externally operable voltage setting device 0Φ to a variable voltage power supply 0) connected to the motor (c) to change the rotational speed of the motor (c). The above seed crystal■
The crystal 0 that has grown as a nucleus is pulled up by the support part (2) that moves in the axial direction of the ball screw (02), which is rotated by the rotational torque of the DC motor 0 transmitted via the reduction gear (2).

[Problems with background technology]

Generally, when growing a single crystal, its length is determined by the pulling speed and the time required for pulling.

Of these, the lifting time is allotted a fixed amount of time in daily routine work, but
The pulling speed varies due to human errors in the set value set on the voltage setting device 0Φ, setting errors in the variable voltage power supply ■, and rotational fluctuations of the DC motor ■ due to mechanical load fluctuations, and may differ from the set value. This creates a gap between the two. Therefore, even if an attempt is made to obtain a single crystal 0 of the required length within a predetermined time, the length will vary.

When such variations occur in the growth of crystals, when the growth length is short, fewer products can be obtained by the same operation, resulting in a disadvantage. On the other hand, if the crystal is too long, the lowest part of the crystal is deformed due to uneven temperature or other reasons, and not only can it not be used for products, but sometimes cracks may occur, making the entire crystal defective.

[Purpose of the invention]

An object of the present invention is to configure a crystal pulling speed side m+ device that can control the pulling speed of a crystal with high precision and grow the crystal to a constant length in a predetermined time.

[Summary of the invention]

A pulse motor connected via a speed reducer to a feed mechanism that linearly moves a support section that supports a seed crystal, a variable bar circuit that drives this pulse motor, and a pulse train oscillation circuit that sends out a pulse train that controls this driver circuit. a frequency dividing circuit that divides the frequency of the pulse train and sends out a divided pulse time interval signal; a reference pulse oscillation circuit that oscillates a reference pulse train; A counting circuit for counting numbers, a comparison value for determining the counting results counted by this counting circuit, and a plurality of dividing constants corresponding to preset crystal pulling speeds are stored, and the counting results are used to calculate the an arithmetic control circuit that performs arithmetic processing with a predetermined frequency division constant selected from a plurality of frequency division constants and sends speed data or a frequency division switching command to the frequency division circuit; and a speed display that displays the speed data. By configuring a crystal pulling speed control I device with the device, the crystal pulling speed can be controlled with high precision and a crystal of a constant length can be grown in a predetermined time.

[Embodiments of the invention]

Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

FIG. 1 shows the configuration of a pulling speed control device in a crystal pulling apparatus which is an embodiment of the present invention.

This crystal pulling device has a high-frequency heating coil (■) connected to a high-frequency power supply (■), a crucible (■) loaded with a crystal raw material is installed inside this coil (2), and the crystal raw material is heated by this high-frequency heating coil (■). is melted and kept at a constant temperature. A support part (2) consisting of a support rod (2) for supporting the seed crystal (1) and a support plate (2) for supporting the support rod (2) is provided on the crucible (2). This support portion ω is a ball screw 0 that is supported by a bearing (not shown) and extends in the vertical direction.
As the ball screw rotates, it can be moved in the axial direction of the ball screw by being guided by a linear guide (not shown).

The above ball screw ■ is directly connected to the output shaft of the reduction gear II (23) which is connected to the output shaft of the pulse motor (support).
It is decelerated at a large reduction ratio of 5000 to 1/20000 and rotated by the rotational torque of the pulse motor.

The pulse motor) is connected to a driver circuit (24) that drives the pulse motor, and this driver circuit (24) includes:
A pulse oscillator (25) that sends out a pulse signal (PS) for controlling this is connected. This pulse oscillator (2
5) The pulse signal (PS) sent from this oscillator (
It can be set variably using the volume provided in 25). Further, a frequency dividing circuit (27) is connected to the output side of the pulse oscillator (25), and a pulse signal (PS) is supplied thereto.

This frequency division circuit (27) has a frequency division ratio set by a frequency division switching command (BK) sent from an arithmetic control circuit (28) connected thereto, and the second frequency division ratio is set based on this set frequency division ratio.
As shown in the figure, the frequency of the pulse signal (PS) is divided and the frequency-divided pulse time interval signal (BP) is generated by the calculation control circuit (2).
8) and the counting circuit (2) connected to this frequency dividing circuit (27).
9).

The counting circuit (29) converts the reference pulse (KP) sent out from the reference pulse oscillator (30) connected to the counting circuit (29) into the frequency-divided pulse time interval signal ( BP) at the pulse interval T1, and at the rising edge of the next pulse interval T2, the counting result (
The number of reference pulses n1) is transferred to the arithmetic control circuit (28).

On the other hand, the divided pulse time interval signal @ (BP) sent to the arithmetic control circuit (28) is converted into distance display data by the counter circuit (31) connected to this arithmetic control circuit (28). It is displayed on the display device (32). The arithmetic control circuit (28) also outputs a comparison value for determining whether the counting result transferred from the counting circuit (29) is within a certain range, and a frequency division constant corresponding to the crystal pulling speed. That is, it stores a plurality of frequency division constants determined by the frequency division ratio of the frequency division circuit (27), and calculates the counting results transferred from the counting circuit (29) from the comparison value and the plurality of frequency division constants. Processing is performed with a constant corresponding to the frequency division ratio set in the selected frequency dividing circuit (27), and the speed display data is sent to the speed display device (33) and the frequency dividing circuit (27)
A branch switching command (8K) is sent to the station.

The relationship between the frequency division ratio and the constant is determined by the resolution of the pulse motor @ and the reduction ratio of the reducer (23). For example, if the reduction ratio is 1/9600, the frequency division ratio is 2,
4,500,00 for 250,000.1/32
9.000.000.1/12 for 0.1/64
For B, 18.000.000. For 1/25B, 36.000.000 is selected.

Now, suppose the frequency division ratio is set to 1716, and the counting circuit (29)
The counting result corresponding to this frequency division ratio is sent to the arithmetic control circuit (2
8), the arithmetic control circuit (28) will be
First, this counting result is compared with a comparison value. As a result, if the counting result is within a certain range, then speed display data is calculated using a constant set corresponding to the frequency division ratio. In addition, if the counting result is out of a certain range, for example if it is determined that the speed is increasing, the frequency dividing circuit (27
) is sent a frequency division switching command (BK) to switch to the next higher frequency division ratio. The frequency divider circuit (27) divides the pulse signal (ps) sent from the pulse oscillator (25) using this newly specified frequency division ratio to obtain the frequency divided pulse time interval Shintan (BP). and sends it to the arithmetic control circuit (28) and the counting circuit (29). Further, if it is determined from the counting result that the speed is on a downward trend, the frequency division ratio is switched to one lower than the above, and the same processing is performed. A flowchart of this process is shown in FIG.

If the above frequency division ratio switching judgment is made using the same comparison value when increasing and decreasing the speed, the frequency division switching command will be sent frequently when the pulling speed is close to the comparison value. It is preferable to set two comparison values corresponding to an upward trend and a downward trend, respectively, and provide hysteresis in the switching judgment.

Furthermore, the switching of the frequency division ratio due to the speed increase or decrease is transmitted to the counting circuit (29) as a change in the pulse interval of the frequency division pulse time interval signal (BP), but the data immediately after the frequency division ratio is changed is is inaccurate, so the arithmetic control circuit (28) sends the frequency division switching command (to B) and after the frequency division pulse time interval signal (BP) is output twice, the calculation control circuit (28) It is preferable to control the counting results transferred from the controller to be processed.

In pulling the crystal, before actually pulling the crystal, the pulse oscillator (25) is operated so that the speed display obtained on the speed display device (33) becomes a predetermined value.
This is done after adjusting the pulse train sent out from 5), but this crystal pulling speed control device can also be operated in the same way to adjust the speed if it becomes necessary to adjust the speed during crystal pulling. can do.

As described above, the speed reduction ratio of the speed reducer (23) is set appropriately large, and the number of pulses of the pulse oscillator (23) and the length of crystal pulling are made to correspond in an integer ratio to eliminate errors in speed calculation.
By setting the dividing ratio and switching it, the display accuracy of the pulled length of the crystal can be reduced to 1/100071111.
1, the length of the obtained crystals is stabilized and the yield per operating time can be improved. Furthermore, since the pulled length of the crystal is digitally displayed with high accuracy, the crystal length can be easily managed and work efficiency can be improved. Also, since the signal is digitized, it has good noise resistance.

In the above embodiment, a counter circuit is connected to the arithmetic control circuit, and the counting results transferred from the counting circuit are converted into distance display data and displayed on the distance display device.
These counter circuits and distance display devices may be omitted.

Further, the reduction ratio of the reduction gear is not limited to the range shown in the above embodiments, but may be selected according to the usage range of the crystal pulling apparatus.

(Effects of the Invention) The support part that supports the seed crystal is driven by a pulse motor connected to the feed mechanism via a reducer, and the rotation speed of this pulse motor can be adjusted with high precision. , it is possible to stably obtain crystals of a certain length in a certain period of time.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a crystal pulling speed control device which is an embodiment of the present invention, FIG. 2 is a diagram showing the timing of the pulses, FIG. 3 is a diagram showing a flowchart of operation management, and FIG. The figure is a diagram showing the configuration of a conventional crystal pulling speed control device.

Claims (1)

[Claims] A pulse motor connected via a reducer to a feed mechanism that linearly moves a support section that supports a seed crystal, a driver circuit that drives this pulse motor, and a pulse oscillation circuit that sends out a pulse train that controls this driver circuit. a frequency dividing circuit that divides the frequency of the pulse train and sends out a divided pulse time interval signal; a reference pulse oscillation circuit that oscillates a reference pulse train; A counting circuit for counting numbers, a comparison value for determining the counting results counted by this counting circuit, and a plurality of dividing constants corresponding to preset crystal pulling speeds are stored, and the counting results are used to calculate the an arithmetic control circuit that performs arithmetic processing with a predetermined frequency division constant selected from a plurality of frequency division constants and sends speed data or a frequency division switching command to the frequency division circuit; and a speed display device that displays the speed data. A crystal pulling speed control device comprising: