JPH03285892A - Crystal pulling-up apparatus - Google Patents

Abstract

PURPOSE:To prevent the dislocation between two tables, when a crystal is pulling up by a pulling-up member through a coarse movement table and a fine movement table, by fixing the fine movement table to the coarse movement table by a stopper. CONSTITUTION:A coarse movement table 4 is lowered by an AC servomotor 9 to dip the tip of the platinum bar 7 fixed to the tip of the revolving shaft 6a of a static pressure air spindle 6 into the molten raw material in a furnace 30. Then, the air spindle 6 is rotated at a set number of revolution selected from the set range of 2-300rpm, and the fine movement table 10 is raised at max. speed of about 3.33mm/min, and the pulling-up is carried out while a single crystal is grown through the seed crystal fixed to the tip of the platinum bar 7. In this case, the stopper part 33 is provided to the fine movement table 10 through a support member 31, a cylinder 32, and a piston rod 32a to prevent the dislocation between the coarse movement table 4 and the fine movement table 10. By this method, the linear motor driving the fine movement table 10 is prevented from receiving abnormal force.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a crystal pulling device, and in particular to a method of growing a crystal by dipping a seed crystal in a molten liquid in a furnace and slowly pulling it while rotating. The present invention relates to a crystal pulling device used.

[Prior Art] Conventionally, the CZ method has been known as a method for manufacturing silicon single crystals for optical elements and ordinary semiconductor elements. This C2
In this method, a seed crystal is immersed in a molten liquid in a crucible and slowly pulled up while rotating to grow the crystal, and the diameter of the crystal is adjusted by the pulling speed and heating temperature. Here, single crystals used for normal semiconductor devices have a relatively simple structure, so the pulling conditions are not so strict, but single crystals used for optical devices have a complex crystal structure, so the pulling conditions are quite strict. required. As a single crystal pulling apparatus used in such a C2 method, one in which a contact type spindle having a rotating shaft at the tip is attached to a table that moves up and down is known. This table was moved up and down by a normal contact type slide.

[Problems to be Solved by the Invention] As mentioned above, the conventional single crystal pulling apparatus has a contact type spindle with a rotating shaft at the tip attached to a table that moves up and down. It moved up and down using a normal contact type slide.

Here, since the C2 method uses a crucible, there is a disadvantage that convection occurs in the liquid in the crucible. When convection occurs, there is a problem that impurities are mixed into the crystal due to the convection, and crystal defects are also generated. Therefore, when pulling a single crystal, it is required to pull the single crystal at a low speed and with uniform movement speed. That is, it is necessary to prevent vibration during pulling as much as possible to suppress the generation of convection.

However, in conventional single crystal pulling equipment, the table that moves up and down to perform the pulling operation of the single crystal as described above is composed of a normal contact type slide, so it is difficult to prevent unevenness in the vertical movement speed. was difficult.

Therefore, the table that moves up and down is composed of a coarse movement table that moves up and down roughly, and a fine movement table that is attached to the coarse movement table and moves finely up and down. It is conceivable to use a contact type slide. With this configuration,
Since the actual pulling operation of the single crystal is performed by a non-contact micro-movement table, it is also possible to prevent vibration during pulling of the single crystal as much as possible and suppress the generation of convection.

However, with this method, the fine movement table uses a motor with a very small thrust compared to the coarse movement table, so if the table was driven only by the motor mentioned above, the coarse movement table would move at a high speed. In some cases, there is a problem in that positional deviation occurs between the coarse movement table and the fine movement table. In such a case, it will be difficult to control the operations of the coarse movement table and the fine movement table, and there will be a problem that accurate control cannot be performed. Further, there is also the problem that a similar positional shift occurs when an abnormality occurs during operation or when an operator operating the device presses an emergency stop button or the like.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a crystal pulling apparatus in which positional deviation between a coarse movement table and a fine movement table does not occur.

[Means for Solving the Problems] The crystal pulling apparatus of the present invention includes a coarse movement table that roughly moves up and down, a fine movement table that is attached to the coarse movement table and moves finely up and down, and a coarse movement table that moves up and down. A stopper is attached to the fine movement table to fix the fine movement table to the coarse movement table when the fine movement table is in use, and a seed crystal is attached to the tip of the stopper. and a pulling member for growing crystals.

[Function] In the crystal pulling apparatus according to the present invention, the coarse movement table is roughly moved up and down, and the fine movement table attached to the coarse movement table is finely moved up and down, and when the coarse movement table is moving up and down, the stopper The fine movement table is fixed to the coarse movement table, a seed crystal is attached to the tip of the pulling member attached to the fine movement table, and the seed is attached to the raw material melted in the furnace and moved upward. Since the crystal is grown, the position of the fine movement table relative to the coarse movement table does not move even if a force greater than the thrust of the drive motor that drives the fine movement table is applied while the coarse movement table is moving up and down.

[Embodiment of the Invention] Figures 18 to 1C are structural diagrams of a single crystal pulling apparatus showing an embodiment of the present invention. Figure 1A or Figure 1
The configuration of the single crystal pulling apparatus will be described with reference to Figure C. First, the single crystal pulling device consists of a surface plate 1, a column 2 attached to the surface plate 1, a coarse movement table 4 attached to the column 2 so as to be movable up and down, and a coarse movement table 4 that moves up and down. The fine movement table 10 includes a fine movement table 1o that can be attached to the fine movement table 10, and an air spindle 6 that is integrally attached to the fine movement table 10.

The coarse movement table 4 is attached to move the coarse movement table 4 up and down, and includes a slide body 3 that constitutes the LM guide 3 together with a slide rail 3a attached to the column 2 side.
b, and a guide portion 5a that serves as a guide for vertical movement of the fine movement table 1o.

The fine movement table 10 includes a movable table part 5b, which together with the guide part 5a constitutes a static pressure air slide 5 for the fine movement table, and a linear scale 11 for detecting the movement position of the fine movement table 10.

The air spindle 6 has a rotating shaft 6a for rotating when pulling a single crystal, and the other end of a wire 15, one end of which is attached to a balance weight 17 for reducing the downward force of the air spindle 6. It includes a hook 61 for attaching.

Furthermore, an AC servo motor 9 connected to a ball screw 8 that moves the coarse movement table 4 up and down by rotation is attached to the column 2, and also reduces the downward force applied to the coarse movement table 4 and the air spindle 6. Pulley bearings 13a, 13b, 13c, 14 serve as guides for wires 15 connected to balance weights 16° 17 for weight reduction.
a, 14b, and 14c are attached. Furthermore, a linear scale 12 is attached to the column 2 for checking the vertical position of the coarse movement table 4.

The tip of the rotating shaft 6a of the air spindle 6 protrudes from the bearing end by about 400 mm, and a platinum rod 7 is attached to the protruding tip of the rotating shaft 6a. A furnace 30 is installed below the platinum rod 7.

Further, the fine movement table 10 is provided with a stopper mechanism for preventing positional deviation between the fine movement table 10 and the coarse movement table 4. That is, this stopper mechanism is composed of a support member 31 attached to the fine movement table 10, a cylinder 32 attached to the support member 31, and a stopper section attached to the piston shaft of the cylinder 32, which will be described later.

Next, the operation of the single crystal pulling apparatus will be explained with reference to FIGS. 1A to 1C. First, the coarse movement table 4 is at the upper limit position of the stroke, and the fine movement table 10 is at the lower limit position of the stroke.

The AC servo motor 9 is driven by a command from a control device (not shown). As a result, the coarse movement table 4 is lowered to the working position. In this state, the tip of the platinum rod 7 attached to the tip of the rotating shaft 6a of the air spindle 6 is
It is in a state where it is soaked in water. In this state, the air spindle 6 is rotated forward or reverse at a rotation speed set within the rotation speed setting range of 2 to 300 rpm. At the same time as this rotation, 1. Raise the fine movement table 10. After this operation is continued for a predetermined time and the single crystal pulling operation is completed, the air spindle 6 is stopped. After that, raise the coarse movement table. Here, the maximum feed rate of the coarse movement table 4 is, for example, 150 mm/min, and this feed rate is used when the platinum rod 7 attached to the tip of the air spindle 6 approaches or retreats from the furnace 30. The drive of the coarse movement table 4 is controlled in a semi-closed loop using a ball screw 8 and an AC servo motor 9, that is, a command value (number of pulses) corresponding to the moving distance of the coarse movement table 4 and a command value (number of pulses) attached to the AC servo motor are controlled. The moving distance of the coarse movement table 4 is controlled by comparing the rotation angles of the encoders and performing feedback control on the difference.

Note that the movement distance of the coarse movement table 4 is confirmed using the linear scale 12.

The maximum feed rate of the fine movement table 10 is, for example, 3.3.
The speed is 3 mm/min. The fine movement table 10 performs a pulling operation when a single crystal is grown by a platinum rod 7 attached to the tip of an air spindle 6, and suppresses the occurrence of convection that causes contamination of impurities and crystal defects. Therefore, it is necessary to prevent vibration during lifting as much as possible. In this embodiment, in response to this, a static pressure air slide is used, and a voice coil type linear motor (to be described later) is used to drive the slide, and a 1/100 μm linear scale 11 is used for closed loop control. is being carried out. That is, the amount of movement of the fine movement table 10 is measured by the linear scale 11, the difference between the measurement result and the value to be driven (command value) is taken, and a drive instruction is given to the drive system so that the difference becomes zero. The drive of the fine movement table 10 is controlled by giving the same. In this embodiment, by controlling in this manner, it is possible to reduce the speed unevenness during pulling of the single crystal, and as a result, vibrations that cause convection can be prevented as much as possible.

Air spindle 6 attached to fine movement table 10
The rotation speed setting range is 2 to 300 r when pulling a single crystal.
It rotates at a set rotational speed within pm while repeating forward or reverse rotation in a constant cycle. Here, in order to grow a single crystal on the platinum rod 7 in a good condition, it is necessary to prevent vibrations due to rotation as much as possible. In response to this, this embodiment employs a hydrostatic air spindle with good rotational performance, so vibrations due to rotation can be effectively prevented and single crystals can be grown in good conditions.

FIG. 2 is a side view for explaining the configuration of the coarse movement table of the single crystal pulling apparatus shown in FIG. 1A. As mentioned above, the coarse movement table 4 includes the slide main body 3b that constitutes the LM guide 3 together with the slide rail 3a attached to the column 2 side, and the guide of the static pressure air slide of the fine movement table 10 (see Fig. 1A). A guide portion 5a is attached. A balance weight 16 is provided to reduce the force applied downward to the coarse movement table 4, and the balance weight 16 and the coarse movement table 4 are connected to pulley bearings 13a, 13b, and 14a.

They are connected by a wire 15 via 14b. The coarse movement table 4 is moved up and down by driving an AC servo motor 9.

3A and 3B are structural diagrams showing details of the LM guide used to move the coarse movement table shown in FIG. 2 up and down. As described above with reference to FIGS. 3A and 3B, the LM guide 3 includes a slide rail 3a that is fixedly installed and serves as a guide during movement, and a slide main body 3b that actually moves up and down. including. A ball 3c is interposed between the slide rail 3a and the slide body 3b, and the ball 3c rotates as the slide body 3b slides.

FIG. 4 is a structural diagram showing details of the hydrostatic air slide used in the fine movement table of the single crystal pulling apparatus shown in FIG. 1A. Referring to FIG. 4, the static pressure air slide includes a guide part 5a that is attached to the coarse movement table 4 and serves as a guide during sliding, and a movable table part 5b that is attached to the fine movement table 10 and moves up and down. The movable table portion 5b is further provided with a bearing air supply hole 5c. By supplying air to this bearing air supply hole 5c,
Movement is possible in a non-contact state, and speed unevenness can be prevented as much as possible.

5A and 5B are structural diagrams showing details of a voice coil type linear motor for vertically moving the fine movement table of the single crystal pulling apparatus shown in FIG. 1A. Referring to FIGS. 5A and 5B, the voice coil type linear motor 20 includes a coil portion 21, a bobbin 22, a center yoke 23, and an outer yoke 24. The linear motor 20 is driven by energizing the coil portion 21 to enable vertical movement. The outer yoke 24 of this linear motor 20 is attached to the coarse movement table 4 (see FIG. 1B), and the movable part of the linear motor 20 is attached to the fine movement table 10. Although the linear motor 2o with a small thrust is used, since the fine movement table is mounted vertically, it is necessary to reduce the downward force. In this embodiment, as a countermeasure against this problem, a balance weight 17 (see FIG. 1c) is provided. This balance weight 17 suspends a weight equivalent to the weight of the fine movement table 10, and fine adjustment of the balance is performed by adding weight to the balance weight 17 side.

FIG. 6 is a cross-sectional structural diagram showing details of the air spindle shown in FIG. 1. Referring to FIG. 6, air spindle 6 consists of a rotating shaft 6a and a stator 6b. The stator 6b includes a hook 61 for connecting the balance weight 17 (see FIG. 1C) via a wire 15, a motor 62 for rotating the rotating shaft 6a, and an air supply hole 63 for supplying air from the outside. .64.65, thrust bearing air supply holes 66.67, and radial bearing air supply holes 68.69, 70.71 that constitute the thrust r bearing. In the air spindle having such a configuration, the rotating shaft 6a is rotated in a non-contact state, and vibrations due to rotation are prevented as much as possible. As a result, convection that occurs when pulling a single crystal can be reduced, and a single crystal with excellent quality characteristics can be grown.

FIG. 7 is a structural diagram showing details of the stopper mechanism shown in FIG. 1C. Referring to FIG. 7, the stopper mechanism includes a support member 31 attached to the fine movement table 10, a cylinder 32 attached to the support member 31, and a cylinder 32 attached to the support member 31.
A stopper portion 33 made of resin is attached to the tip of the piston shaft 32a. The cylinder 32 is driven by a solenoid valve (not shown), and the operating conditions of the solenoid valve are set in advance in the control system. Possible conditions for the stopper mechanism to operate include, for example, when the coarse movement table 4 is moving up and down, when an abnormal signal is generated from the control system, or when the emergency stop button is pressed. By providing this stopper mechanism, when the coarse movement table 4 moves at a high speed, the thrust of the linear motor 20 (see Figures 5A and 5B) is defeated by the force generated by the movement of the coarse movement table 4, and the coarse movement table 4 moves at a high speed. Inconveniences such as misalignment between the moving table 4 and the fine moving table 10 can be prevented. Also,
Even if an abnormality occurs during operation and an abnormal signal is output from the control system to turn off the control of the fine movement table 10 and the coarse movement table 4, the position between the coarse movement table 4 and the fine movement table 10 due to the chronic force caused by movement Misalignment can be prevented from occurring. Furthermore, the same effect as above can be obtained when the operator presses the emergency stop button.

As described above, by providing the fine movement table 10 with the stopper mechanism using the air cylinder 32, it is possible to effectively prevent positional deviation between the coarse movement table 4 and the fine movement table 10. It is also possible to prevent abnormal force from being applied to the drive linear motor 20 of 10.

As explained above, the single crystal pulling apparatus in this embodiment has a vertically moving operating section divided into a coarse movement table 4 and a fine movement table 10.
Movement of the fine movement table 10 is maintained in a non-contact manner by using the non-contact, high-resolution linear scale 11 and linear motor 20 as well as the static pressure air slides 5a, 5b.

Further, by controlling the drive of the fine movement table 10 using closed loop control, it is possible to pull a single crystal at an extremely low speed and with no speed unevenness.

In addition, by adopting balance weights 16 and 17 for each of the coarse movement table 4 and fine movement table 10, excessive downward force is not applied to the linear motor when pulling a single crystal, and the amount of heat generated by the motor is also reduced. It becomes less.

As a result, power consumption can be reduced.

Further, an air spindle 6 is attached to the fine movement table 10, and a platinum rod 7 for pulling the single crystal is connected to the rotating shaft 6a.
Since the rotating shaft 6a is structured to rotate, the rotation of the rotating shaft 6a is performed without contact and vibrations are reduced, so that convection that occurs during crystal pulling can be prevented as much as possible, and single crystals with excellent quality characteristics can be grown. be able to. Further, since the pulling speed of the beam near motor 20 allows the number of rotations during pulling to be easily controlled by the air spindle 6, various pulling conditions can be easily controlled.

[Effects of the Invention] As described above, according to the present invention, the coarse movement table roughly moves up and down, the fine movement table attached to the coarse movement table moves slightly up and down, and the coarse movement table moves up and down. When the fine movement table is fixed to the coarse movement table with a stopper, a seed crystal is attached to the tip of the pulling member attached to the fine movement table, the seed is attached to the molten raw material in the furnace, and the material is moved upward. By growing crystals, the position of the fine movement table relative to the coarse movement table will not move even if a force greater than the thrust of the drive motor that drives the fine movement table is applied while the table is moving up and down. No positional deviation occurs between the moving table and the fine moving table.

As a result, there is no problem in controlling the operation.

[Brief explanation of the drawing]

Figures 1A to 1C are structural diagrams of a single crystal pulling apparatus showing one embodiment of the present invention, and Figure 2 is a diagram for explaining the structure of the coarse movement table of the single crystal pulling apparatus shown in Figure 1A. The side view, Figures 3A and 3B are structural diagrams showing details of the LM guide used for vertical movement of the coarse movement table shown in Figure 2, and Figure 4 is the single crystal pulling shown in Figure 1A. A structural diagram showing details of the static pressure air slide used in the fine movement table of the device, and Figures 5A and 5B are details of the linear motor for moving the fine movement table of the single crystal pulling device shown in Figure 1A up and down. 6 is a cross-sectional structural diagram showing details of the air spindle shown in FIG. 1A, and FIG. 7 is a structural diagram showing details of the stopper mechanism shown in FIG. 1C. In the figure, 3a is a slide rail, 3b is a slide body, 4 is a coarse movement table, 5a is a guide part, 5b is a movable table part, 6 is an air spindle, 6a is a rotating shaft, 7 is a platinum rod, 8 is a ball screw, 9 is an AC servo motor, 10 is a fine movement table, 11 is a linear scale, 15 is a wire,
16 is balance weight, 17 is balance weight, 2
0 is a linear motor, 30 is a furnace, 32 is a cylinder, 32a
3 is a piston shaft, and 33 is a stopper portion. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] A coarse movement table that roughly moves up and down; a fine movement table that is attached to the coarse movement table and moves finely up and down; and when the coarse movement table is moving up and down, the fine movement table is moved vertically. a stopper for fixing it to the table, and a pulling device that is attached to the fine movement table and has a seed crystal attached to its tip, and that the seed is attached to the molten raw material in the furnace and moves upward to grow the crystal. A crystal pulling device including a member.