JPS5914433B2 - Manufacturing equipment for band-shaped silicon crystals - Google Patents

Description

[Detailed description of the invention] The present invention relates to an apparatus for manufacturing band-shaped silicon crystals.

As shown in FIG. 1, the band-shaped silicon crystal is produced by arranging a capillary die 3 (30, 3□) (hereinafter simply referred to as die) for forming a slit in a quartz crucible 2 containing a silicon melt 1. It is obtained by bringing a seed crystal (not shown) into contact with the melt 1 rising through the slit and pulling it up at a predetermined temperature condition and pulling speed.

4 shows a pulled band-shaped silicon crystal.

In this case, the width of the obtained band-shaped silicon crystal 4 is theoretically regulated by the width of the tip of the die 3.

By the way, in the conventional method, as the temperature distribution in the longitudinal direction of the tip of the die 3 is shown in FIG. 2, the temperature and pulling speed of the die 3 are constant because the temperature is low at both ends A and B. Also, there is a problem that the die 3 and the band-shaped silicon crystal 4 are stuck together.

An effective method to prevent this is to
There is a method of growing a band-shaped silicon crystal of a constant width between two points on the inner side of the silicon crystal without using the silicon crystal.

Conventional techniques for controlling the width include (1) adjusting the pulling speed and system temperature, (2) controlling the distance between the heat source and the ends of the die 3, and (3) controlling the distance between the ends of the die 3 in the longitudinal direction. There is a method of installing a heater and adjusting the temperature.

In method (1), when the band-shaped silicon crystal becomes thicker than a specified width, the pulling speed or system temperature is increased, and when it becomes thinner, the opposite control is performed.

In the method (2), when the band-shaped silicon crystal becomes thicker than a specified width, the distance between the heat source and the end of the die is brought closer, and when it becomes thinner, the opposite control is performed.

In method (3), the heater temperature is increased when the band-shaped silicon crystal becomes thicker than a specified width, and vice versa when the band-shaped silicon crystal becomes thinner.

However, these conventional methods require complicated operations and it is difficult to obtain band-shaped silicon crystals with a constant width.

As a countermeasure, an automatic control mechanism using an infrared ITV camera may be considered, but there are problems in determining the monitoring unit and adjusting the PID value in the feedback mechanism, and the device is expensive.

Furthermore, the structure of the high-temperature section becomes complicated due to the movement mechanism of the auxiliary heat source and the structure of the auxiliary heater, and at the same time, the chamber becomes large, so the unit cost of the device becomes extremely high, making it unsuitable for industrial use.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide a device that can stably and precisely control the width of a band-shaped silicon crystal without requiring a large-scale device. The goal is to provide the following.

In other words, the present invention creates a temperature distribution in which the temperature of the die is forcibly increased by making cuts at predetermined distances from both ends of the die in the longitudinal direction. The above objective is achieved by preventing the width of the crystal from expanding.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows the main parts of one embodiment in correspondence with FIG. 1. What differs from FIG. 1 is that a notch 5 (51 , 5□), and the width of the obtained band-shaped silicon crystal 40 is
This is to make it regulated by

FIG. 4 shows the temperature distribution in the longitudinal direction (width direction) at the tip of the die 3 when the notch 5 is provided in this way.
The temperature becomes higher at points C and D, which correspond to the cuts 5 on the inside of both ends A and B, and as a result, the band-shaped silicon crystal 4 does not spread beyond points C and D.

The fact that the width of the band-shaped crystal obtained in this example is well controlled will be explained in detail.

FIG. 5 shows an example of the contact state of the four ends of the silicon crystal obtained during crystal pulling with the melt 1.

A is the state when the crystal becomes thicker in the width direction, b is the state when it remains unchanged, and C is the state when the crystal becomes thinner in the width direction.

Now, if we adjust the system temperature and pulling speed with the conventional configuration and enter a steady state with the liquid shape at the end of the crystal as shown in (a), the crystal will gradually spread in the width direction and remain as it is at both ends of the die 3.
, H, the temperature at the end of the die is low, so the distance between the crystal 4 and the die 3 becomes smaller, the contact angle ψ increases, and the crystal sticks to the die.

On the other hand, in the embodiment shown in FIG. 3, the crystal width increases in the same manner as above until the crystal reaches the positions C and D of the notch 5 of the die 3, but when it reaches the C and D points, the crystal width increases. The state of contact with the liquid at the end becomes further from the shape shown in FIG. 5a to that shown in FIG.

Also, in an attempt to make the crystal thicker, the pulling speed was lowered9.If the system temperature was lowered, the crystal would not thicken and would stick to the die.

In fact, in the embodiment shown in FIG. 3, by reducing the pulling speed by about 3% when the crystal width reaches points C and D, the width of the pulled band-shaped silicon crystal 40 is regulated at points C and D. The width change of the pulled crystal was about ±100μ per meter.

This value is a precision that is difficult to obtain even when automatic control of the band width is performed by external temperature control using an ITV camera.

As described above, according to the present invention, the width of the band-shaped silicon crystal can be automatically controlled with high precision.

In addition, the conventional technology had the problems of a complicated structure, an expensive device, and a difficult operation, but the present invention solves all of these drawbacks of the conventional technology, and has a simple structure and a low-cost device. A major feature is that no special width control operation is required.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the state of pulling a conventional band-shaped silicon crystal, FIG. 2 is a diagram showing the temperature distribution at the tip of the die, and FIG. 3 is a diagram showing the state of crystal pulling in an embodiment of the present invention. ,
FIG. 4 is a diagram showing the temperature distribution at the tip of the die, and FIG. 5 is a diagram showing an example of the state of contact with the melt at the end of the crystal to be pulled. 1...Silicon melt, 2...Quartz crucible, 31°32...Capillary die, 4.
・・・・・・Striped silicon crystal, 51,5□・・・・・・
Notch.

Claims (1)

[Claims] 1. A capillary die having a slit is arranged in a crucible containing a silicon melt, a seed crystal is brought into contact with the melt rising through the slit, and the band-shaped silicon crystal is pulled up by pulling up the seed crystal. In the device,
An apparatus for producing a band-shaped silicon crystal, characterized in that cuts are provided at the tip of the capillary die at predetermined distances from both longitudinal ends thereof.