JPH0615435B2 - Single crystal pulling speed calculator - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a single crystal pulling speed calculation device in a device for pulling a single crystal used in electronic parts and the like.

[Technical background of the invention]

A required single crystal used for an electronic component is usually manufactured by immersing a seed crystal in a liquid surface of a raw material melt which is heated and melted at a predetermined temperature, and pulls the seed crystal at a predetermined speed. In order to form this single crystal with a predetermined diameter and length, it is necessary to precisely control the temperature of the raw material melt and the pulling rate of the single crystal. Conventionally, as shown in FIG.
The high-frequency heating coil (2) arranged around the crucible (1) is supplied with high-frequency power from the power supply (3) to melt the melt in the crucible (1).
DC which controls (4) to a temperature at which a single crystal (5) having a required diameter can be obtained and which drives a supporting part (7) supporting the single crystal (6).
This is done by giving a command to the variable voltage power supply (9) connected to the motor (8) from the externally operable voltage setting device (10) to change the rotation speed of the motor (8). The single crystal (5) grown by using the seed crystal (6) as a nucleus has its axis rotated by the ball screw (12) rotated by the rotation torque of the DC motor (8) transmitted through the speed reducer (11). It is pulled up by the support (7) which moves in the direction.

[Problems of background technology]

Generally, when growing a single crystal, its length is determined by the pulling rate and the time required for pulling. Of these, the pull-up time depends on the routine work performed daily.
Almost constant time is allotted, but the pulling speed is
The set value changes due to human error of the set value set in the voltage setting device (10), setting error of the variable voltage power supply (9), and rotation fluctuation of the DC motor (8) due to mechanical load fluctuation. There is a gap between and. Therefore, even if an attempt is made to obtain a single crystal (5) having a required length within a predetermined time, the length will vary.

When the growth of the single crystal varies as described above, when the growth length is short, the number of products obtained by the same operation is reduced, which causes a disadvantage. On the contrary, when the length is long, the bottom of the single crystal is deformed due to non-uniform temperature and other reasons, and not only cannot be used for a product, but also cracks sometimes occur to make the whole single crystal defective.

[Object of the Invention]

An object of the present invention is to configure a single crystal pulling rate calculation device capable of accurately calculating the pulling rate of a single crystal and growing it to a constant length in a predetermined time.

[Outline of Invention]

A pulse motor connected via a speed reducer to a feed mechanism that linearly moves a support portion that supports a seed crystal, a driver circuit that drives this pulse motor, and a pulse train oscillation circuit that sends a pulse train that controls this driver circuit. A dividing circuit for dividing the pulse train to send a divided pulse time interval signal, a reference pulse oscillating circuit for oscillating a reference pulse train, and a pulse for the reference pulse train at the pulse interval of the divided pulse time interval signal. A counting circuit for counting the number, a comparison value for judging the counting result counted by this counting circuit, and a plurality of frequency division constants corresponding to a preset single crystal pulling speed are stored, and the counting result is used as the comparison value. And a predetermined frequency division constant selected from among a plurality of frequency division constants, and the speed data or a frequency division switching command is sent to the frequency division circuit. A single crystal pulling rate calculation device is composed of a calculation control circuit, and the single crystal pulling rate is controlled with high accuracy by controlling based on the calculation result to grow a single crystal of a certain length in a predetermined time. I was able to do it. At this time, it is preferable to provide a speed display device for displaying the speed data so that the pulling speed of the single crystal can be confirmed.

A known method may be used as the control means based on the calculation result. For example, the signal from the calculation control circuit is
There is a method of supplying the pulse oscillator through the / A converter or the like.

Example of 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 calculation device in a single crystal pulling device which is an embodiment of the present invention. This single crystal pulling apparatus has a high-frequency heating coil (2) connected to a high-frequency power source (3), and a crucible (1) loaded with a single crystal raw material is installed inside the coil (2). The crystal raw material is melted and kept at a constant temperature by heating the high frequency heating coil (2). On the crucible (1), a supporting rod (20) supporting the seed crystal (6) and a supporting plate (20) supporting the supporting rod (20).
Is provided with a support part (7). This support (7)
Is attached to a ball screw (12) that extends in the vertical direction by being supported by a bearing (not shown), and the rotation of the ball screw (12) guides it to a linear guide (not shown) so that the shaft of the ball screw (12) is You can move in any direction.
The ball screw (12) is directly connected to the output shaft of the speed reducer (23) connected to the output shaft of the pulse motor (22), and is 1/5000 to 1/20.
It is decelerated with a large reduction ratio of 000 and is rotated by the rotation torque of the pulse motor (22).

The pulse motor (22) is a driver circuit that drives it.
A pulse oscillator (25) that is connected to the driver circuit (24) and sends out a pulse signal (PS) that controls the driver circuit (24) is connected to the driver circuit (24). The pulse signal (PS) sent from the pulse oscillator (25) can be variably set by the volume provided in the oscillator (25). Further, on the output side of the pulse oscillator (25), a frequency dividing circuit (27) is connected, and a pulse signal (PS)
Are being supplied.

The frequency divider circuit (27) is connected to the arithmetic control circuit (2
The division ratio is set by the division switching command (BK) sent from 8), and the pulse signal (PS) is divided by the set division ratio as shown in FIG. The pulse time interval signal (BP) is sent to the arithmetic control circuit (28) and the counting circuit (29) connected to the frequency dividing circuit (27).

The counting circuit (29), the reference pulse (KP) sent from the reference pulse oscillator (30) connected to the counting circuit (29),
As shown in FIG. 2, counting is performed at the pulse interval T ₁ of the divided pulse time interval signal (BP), and the counting result (the number of reference pulses n ₁ ) at the rising edge of the pulse at the next pulse interval T _2.
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), and the distance display data is displayed. Displayed on device (32). Moreover, this arithmetic control circuit (28)
The comparison value for determining whether or not the counting result transferred from the counting circuit (29) is within a certain range, and the division constant corresponding to the pulling rate of the single crystal, that is, the division circuit (27). A plurality of frequency division constants stored with a frequency division ratio are stored, and the counting result transferred from the above counting circuit (29) is used as the frequency division circuit (27) selected from the comparison value and the plurality of frequency division constants. ) Performs arithmetic processing with the constant corresponding to the division ratio set in
Data for speed display is displayed on the speed display device (33) and frequency divider circuit
Send the frequency division switching command (BK) to (27).

The relationship between the frequency division ratio and the constant can be determined by the resolution of the pulse motor (22) and the reduction ratio of the speed reducer (23).
When set to 9600, 2 / 250,000, 1/32 for a division ratio of 1/16
For 4,500,000, 1/64 for 9,000, 1/28
18,000,000 for, and 36,000,000 for 1/256.

If the frequency division ratio is set to 1/16 and the counting result corresponding to the frequency division ratio is transferred to the arithmetic control circuit (28) from the counting circuit (29), the arithmetic control circuit (28) first The count result is compared with the comparison value. As a result, if the counting result is within a certain range, then the speed display data is calculated using the constant set corresponding to the frequency division ratio. If the counting result is out of the fixed range, for example, if it is determined that the speed is increasing, the frequency division switching command (B
K) is sent to switch to the next higher division ratio. Divider circuit
(27) divides the pulse signal (PS) sent from the pulse oscillator (25) by this newly specified division ratio to create a divided pulse time interval signal (BP), and calculates this. Control circuit (2
8) and the counting circuit (29). Further, when it is determined from the counting result that the speed is decreasing, the frequency division ratio is switched down by one and the same processing is performed as described above. A flowchart of this process is shown in FIG.

If the same comparison value is used for speed increase and speed decrease, the frequency division switching command will be sent frequently when the pulling speed is close to the comparison value. It is advisable to set two comparison values corresponding to the rising tendency and the falling tendency, respectively, and to provide a hysteresis for the switching judgment.

In addition, the switching of the frequency division ratio due to the speed increase or decrease is performed by the frequency division pulse time interval signal (BP) to the counting circuit (29).
Although it is transmitted as a change in the pulse interval of, the data immediately after switching the division ratio is incorrect, so the arithmetic control circuit (28)
May be controlled so that the counting result transferred from the counting circuit (29) is processed after the dividing pulse time interval signal (BP) is output twice after the division switching command (BK) is transmitted. .

Incidentally, the pulling of the single crystal, prior to the actual pulling of the single crystal, by operating the pulse oscillator (25), the speed display device (33)
This oscillator (2
This is performed after adjusting the pulse train sent from (5) .This single crystal pulling speed calculation device operates in the same way even when it becomes necessary to adjust the speed during pulling of the single crystal. Can be adjusted.

As described above, the reduction ratio of the speed reducer (23) is set to an appropriate size, and the number of pulses of the pulse oscillator (23) and the single crystal pulling length are associated with an integer ratio to eliminate the error in the speed calculation, And by performing the division ratio setting and its switching, the display accuracy of the pulling length of the single crystal can be maintained at 1/1000 mm, so the length of the obtained single crystal is stable,
The yield per operating time can be improved. Further, since the pulling length of the single crystal is digitally displayed with high accuracy, the management of the single crystal length becomes easy and the workability can be improved. Further, since the signal is digitized, it has good noise resistance.

In the above embodiment, the counter circuit is connected to the arithmetic control circuit, and the counting result transferred from the counting circuit is converted into the distance display data and displayed on the distance display device.
The counter circuit and the distance display device may be omitted.

The speed reduction ratio of the speed reducer is not limited to the range shown in the above embodiment, and may be selected according to the range of use of the single crystal pulling apparatus.

〔The invention's effect〕

With the single crystal pulling calculation device of the present invention, the single crystal pulling speed can be calculated with high accuracy. The support unit that supports the seed crystal is driven by a pulse motor connected to the feed mechanism through a speed reducer, and the rotation speed of this pulse motor is controlled by controlling the pulse oscillator based on the result of this calculation. Since the structure can be adjusted with accuracy, a single crystal having a certain length can be stably obtained in a predetermined time.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of a single crystal pulling rate computing device which is an embodiment of the present invention, FIG. 2 is a diagram showing the timing of its pulses, FIG. 3 is a diagram showing a flow chart of operation management, FIG. FIG. 4 is a diagram showing a configuration of a conventional single crystal pulling rate calculation device. (1) …… crucible, (2) …… high frequency heating coil (3) …… high frequency heating power supply, (6) …… seed crystal (7) …… supporting part, (12) …… ball screw (22)… … Pulse motor, (23) …… Reducer

Claims (2)

[Claims] 1. A pulse motor connected to a feed mechanism for linearly moving a support portion supporting a seed crystal via a speed reducer,
A driver circuit that drives this pulse motor, a pulse oscillator circuit that sends out a pulse train that controls this driver circuit, a divider circuit that divides the pulse train and sends a divided pulse time interval signal, and a reference pulse train that oscillates. A reference pulse oscillating circuit, a counting circuit for counting the number of pulses of the reference pulse train at the pulse intervals of the divided pulse time interval signal, a comparison value for judging the counting result counted by the counting circuit and a preset value A plurality of frequency division constants corresponding to the single crystal pulling speed are stored, and the counting result is subjected to arithmetic processing with a predetermined frequency division constant selected from these comparison values and a plurality of frequency division constants to obtain speed data or the above frequency division. An arithmetic control circuit for transmitting a frequency division switching command to a frequency circuit, a single crystal pulling rate arithmetic device. 2. The single crystal pulling rate calculation device according to claim 1, further comprising a velocity display device for displaying the velocity data.