JP2838168B2 - Crystal pulling device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal pulling apparatus, and more particularly, to a method for growing a crystal by dipping a seed crystal in a liquid melted in a furnace and slowly pulling it while rotating. The present invention relates to a crystal pulling apparatus.

[Prior Art] Conventionally, a CZ method is known as a method for producing a silicon single crystal for an optical element or a normal semiconductor element. The CZ method is a method in which a seed crystal is immersed in a liquid melted in a crucible and slowly pulled up while rotating to grow the crystal. The crystal diameter is adjusted by the pulling speed and the heating temperature.
Here, a single crystal for a normal semiconductor element has a relatively simple structure, so that the pulling conditions are not so strictly required. However, a single crystal used for an optical element has a complicated crystal structure, so that quite strict conditions are required. Is done. Conventionally, as a single crystal pulling apparatus used for such a CZ method, a single crystal pulling apparatus 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. The table is moved up and down by a normal contact type slide.

[Problems to be Solved by the Invention] As described above, the single crystal pulling apparatus used in the conventional CZ method has a contact type spindle equipped with a rotating shaft at the tip mounted on a table that moves up and down. This table was moved up and down by a normal contact type slide.

By the way, since the CZ method uses a crucible, there is an inconvenience that convection occurs in the liquid in the crucible. When this convection occurs, there is a problem that impurities are mixed into the crystal due to the convection, and there is a problem that crystal defects occur. For this reason, at the time of pulling a single crystal, it is necessary to minimize the vibration caused by the pulling and suppress the generation of convection.

However, in the conventional single crystal pulling apparatus, since the rotation of the pulling rod at the time of pulling the single crystal is performed by the contact type spindle, it is difficult to effectively prevent the vibration due to the rotation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a crystal pulling apparatus capable of minimizing vibration due to rotation during crystal pulling.

[Means for Solving the Problems] A crystal pulling apparatus according to the present invention is provided with a vertically moving elevating table including a table guided by up and down movement by a static pressure air slide; And a pulling member for growing the crystal by rotating the seed material while rotating in a statically supported state and growing the crystal in the furnace with the seed crystal attached thereto.

[Action] In the crystal pulling apparatus according to the present invention, the lifting table is raised and lowered, and a seed crystal is attached to the tip of a lifting member attached to the lifting table, and the seed is melted in the furnace. The crystal is grown by being moved upward while rotating in a state where the crystal is supported by the static pressure, so that the rotation at the time of pulling the crystal is performed under static pressure.

[Embodiment of the Invention] Figs. 1A to 1C are views showing the production of a single crystal pulling apparatus according to an embodiment of the present invention. The configuration of the single crystal pulling apparatus will be described with reference to FIGS. 1A to 1C.
First, the single crystal pulling apparatus includes a base 1, a support 2 mounted on the base 1, a coarse movement table 4 mounted on the support 2 so as to be vertically movable, and a vertical movement on the coarse movement table 4. Fine movement table 10 and fine movement table 10
And an air spindle 6 which is integrally mounted on the air spindle.

The coarse moving table 4 is mounted to move the coarse moving table 4 up and down, and a slide main body 3b constituting the LM guide 3 together with a slide rail 3a mounted on the column 2 side.
And a guide portion 5a that guides the fine movement table 10 up and down.

The fine movement table 10 is a movable table part which forms the static pressure air slide 5 for the fine movement table together with the guide part 5a.
5b 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 the single crystal when it is pulled up, and a wire 15 having one end attached to a balance weight 17 for reducing a force applied to the air spindle 6 in a downward direction. Hooks for mounting 61
And

An AC servomotor 9 to which a ball screw 8 for moving the coarse movement table 4 up and down by rotation is connected is attached to the column 2, and a downward force applied to the coarse movement table 4 and the air spindle 6 is applied to the support 2. Pulley bearings 13a, 13b, 13c, 14a, 14b, and 14c serving as guides for wires 15 connected to balance weights 16 and 17 for reduction are mounted. Further, a linear scale 12 for confirming the vertical position of the coarse movement table 4 is attached to the column 2.

The tip of the rotating shaft 6a of the air spindle 6 is approximately
A platinum rod 7 is attached to the tip of the projected rotating shaft 6a. Furnace 30 below platinum rod 7
Is installed.

Further, the fine movement table 10 is provided with a stopper mechanism for preventing a displacement between the fine movement table 10 and the coarse movement table 4. That is, 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 stopper attached to a piston shaft of the cylinder 32 described later.

Next, the operation of the single crystal pulling apparatus will be described 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 servomotor 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 6 a of the air spindle 6 is in a state of being immersed in the furnace 30. In this state, the air spindle 6 is rotated forward or backward at a rotation speed set from a rotation speed setting range of 2 to 300 rpm. At the same time as this rotation, the fine movement table 10 is raised. After performing this operation for a predetermined time and completing the work of pulling the single crystal,
The air spindle 6 is stopped. Thereafter, the coarse movement table is raised. Here, the feed rate of the coarse movement table 4 is, for example, 150 mm / min at the maximum, 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 coarse movement table 4 is driven in a semi-closed loop using a ball screw 8 and an AC servomotor 9, that is, a command value (number of pulses) corresponding to the movement distance of the coarse movement table 4 and attached to the AC servomotor. The moving distance of the coarse movement table 4 is controlled by comparing the rotation angles of the encoders and performing feedback control of the difference. The moving distance of the coarse movement table 4 is confirmed by the linear scale 12.

The feed speed of the fine movement table 10 is, for example, 3.33 mm at the maximum.
/ min. The fine movement table 10 performs a pulling operation when a single crystal is grown by the platinum rod 7 attached to the tip of the air spindle 6, and suppresses the generation of convection which causes impurities and crystal defects. Therefore, it is necessary to minimize vibration during pulling. In this embodiment, in response to this, a static pressure air slide is used, the vibration is performed using a voice coil type linear motor described later, and a closed loop is formed by using a linear scale 11 of 1/100 μm. Controlling. 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 moved (command value) is obtained, and a drive instruction is sent to the drive system so that the difference becomes zero. The drive of the fine movement table 10 is controlled by the application. In the present embodiment, by performing such control, it is possible to reduce the unevenness in the speed at the time of pulling the single crystal, and as a result, it is possible to prevent vibrations that cause convection as much as possible.

Air spindle 6 mounted on fine movement table 10
When the short crystal is pulled, it is rotated while the normal rotation or the reverse rotation is repeated in a constant cycle at a rotation speed set in a rotation speed setting range of 2 to 300 rpm. Here, in order to grow a single crystal on the platinum rod 7 in a favorable state, it is necessary to minimize vibration due to rotation. The present embodiment responds accordingly.
Since a static pressure air spindle having good rotation performance is employed, vibration due to rotation can be effectively prevented, and a single crystal can be grown in a good state.

FIG. 2 is a side view for explaining a configuration of a coarse movement table of the single crystal pulling apparatus shown in FIG. 1A. As described above, on the coarse movement table 4, the slide main body that constitutes the LM guide 3 together with the slide rail 3 a attached to the column 2 side
3b and a guide portion 5a serving as a guide for a static pressure air slide of the fine movement table 10 (see FIG. 1A) are mounted. A balance weight 16 is provided to reduce the force applied below the coarse movement table 4, and the balance weight 16 and the coarse movement table 4 are connected to pulley bearings 13a, 13b, 14
They are connected by a wire 15 via a and 14b. The vertical movement of the coarse movement table 4 is performed by driving the AC servomotor 9.

3A and 3B are structural diagrams showing details of an LM guide used for moving the coarse movement table shown in FIG. 2 up and down. With reference to FIGS. 3A and 3B, as described above, the LM guide 3 is fixedly installed and has a slide rail 3a serving as a guide for movement, and a slide body 3b actually moving up and down. including. A ball 3c is interposed between the slide rail 3a and the slide body 3b, and the ball 3c rotates with the sliding operation of the slide body 3b.

FIG. 4 is a structural diagram showing details of a static pressure air ride used for a fine movement table of the single crystal pulling apparatus shown in FIG. 1A. Referring to FIG. 4, the static pressure air slide is attached to the coarse movement table 4 and serves as a guide for sliding, and a vertically movable movable table 5b attached to the fine movement table 10 side. 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, in a non-contact state,
It is possible to move, and uneven speed 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 a fine movement table of the single crystal pulling apparatus shown in FIG. 1A. No.
Referring to FIG. 5A and FIG. 5B, the voice coil type linear motor 20 includes a coil part 21, a bobbin 22, a center yoke 23, and an outer yoke 24. The drive of the linear motor 20 can be moved up and down by energizing the coil unit 21. The outer yoke 24 of the 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 20 has a small thrust, the fine movement table is mounted vertically, so it is necessary to reduce the downward force. In the present embodiment, a balance weight 17
(See FIG. 1C). This balance weight 17
Is suspended by a weight corresponding to the weight of the fine movement table 10, and fine adjustment of the balance is performed by adding a weight on the balance weight 17 side.

FIG. 6 is a sectional structural view showing details of the air spindle shown in FIG. Referring to FIG. 6, air spindle 6 includes a rotating shaft 6a and a stator 6b. Stator
6b includes a hook 61 for connecting the balance weight 17 (see FIG. 1C) via the 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 constituting a thrust bearing, and radial bearing air supply holes 68, 69, 70, 71. In the air spindle having such a configuration, the rotating shaft 6a is rotated in a non-contact state, and vibration due to the rotation is prevented as much as possible. As a result, convection generated when the single crystal is pulled can be reduced, and a single crystal having 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 mounted on fine movement table 10 and a support member.
Cylinder 32 attached to 31 and stopper portion 33 made of resin attached to the tip of piston shaft 32a of cylinder 32
And The cylinder 32 is driven by a solenoid valve (not shown), and the operating condition of the solenoid valve is set in advance in a control system. Conditions for the operation of the stopper mechanism include, for example, a case where the coarse movement table 4 is moving up and down, a case where an abnormal signal is generated from the control system, and a case where the emergency stop button is pressed. By providing the stopper mechanism, when the coarse movement table 4 moves at a high speed, the thrust of the linear motor 20 (see FIGS. 5A and 5B) loses the force generated by the movement of the coarse movement table 4 and It is possible to prevent the inconvenience that a displacement occurs between the moving table 4 and the fine moving table 10. In addition, abnormalities occur during driving,
Even if an abnormal signal is output from the control system and the control of the fine movement table 10 and the coarse movement table 4 is turned off, it is possible to prevent the positional displacement between the coarse movement table 4 and the fine movement table 10 due to the chronic force due to the movement. Can be. Further, even when the operator presses the emergency stop button, the same effect as described above can be obtained.

As described above, by providing the fine movement table 10 with the stopper mechanism using the air cylinder 32, the displacement between the coarse movement table 4 and the fine movement table 10 can be effectively prevented. It is also possible to prevent an abnormal force from being applied to the linear motor 20 for driving the motor 10.

As described above, the single crystal pulling apparatus according to the present embodiment is configured such that the operation unit that moves up and down is divided into the coarse movement table 4 and the fine movement table 10, and the fine movement table 10 includes
By using the non-contact, high-resolution linear scale 11 and linear motor 20, and the static pressure air slides 5a, 5b, the movement of the fine movement table 10 is maintained in a non-contact manner. Further, by controlling the driving of the fine movement table 10 by the closed loop control, it is possible to realize the pulling of the single crystal at an extremely low speed and without unevenness in the speed.

Also, by adopting the balance weights 16 and 17 for the coarse movement table 4 and the fine movement table 10, respectively,
When the single crystal is pulled, no excessive force is applied to the linear motor downward, and the amount of heat generated by the motor is reduced. As a result, power consumption can be reduced.

Furthermore, since the air spindle 6 is attached to the fine movement table 10 and the platinum rod 7 for pulling the single crystal connected to the rotating shaft 6a is rotated, the rotation of the rotating shaft 6a is performed in a non-contact manner, thereby reducing vibration. Therefore, convection during crystal pulling can be prevented as much as possible, and short crystals with excellent quality characteristics can be grown. Further, since the pulling speed can be easily controlled by the linear motor 20 and the rotation speed at the time of pulling can be easily controlled by the air spindle, various pulling conditions can be easily controlled.

[Effects of the Invention] As described above, according to the present invention, the elevating table is vertically moved up and down, and a seed crystal is attached to the tip of a pulling member attached to the elevating table, and the melted raw material in the furnace is added. By growing the crystal by moving it up and down while rotating with the seed attached and supported by static pressure, the rotation during crystal pulling is performed statically, so vibrations due to rotation during crystal pulling are reduced. It can be prevented as much as possible. As a result, the quality characteristics of the crystal can be improved.

[Brief description of the drawings]

1A to 1C are structural diagrams of a single crystal pulling apparatus showing one embodiment of the present invention, and FIG. 2 is a view for explaining a configuration of a coarse movement table of the single crystal pulling apparatus shown in FIG. 1A. 3A and 3B are structural views showing details of the LM guide used to move the coarse movement table shown in FIG. 2 up and down, and FIG. 4 is a single crystal pulling up shown in FIG. 1A. FIG. 5A and FIG. 5B are structural views showing details of the static pressure air slide used for the fine movement table of the apparatus, and FIGS. 5A and 5B show a linear motor for moving the fine movement table of the single crystal pulling apparatus shown in FIG. 1A up and down. FIG. 6 is a structural view showing details, FIG. 6 is a sectional structural view showing details of the air spindle shown in FIG. 1A, and FIG.
FIG. 3 is a structural diagram showing details of a stopper mechanism shown in the figure. In the figure, 3a is a slide rail, 3b is a slide body,
4 is a coarse moving 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 a balance weight, 17 is a balance weight, 20 is a linear motor, 30
Is a furnace, 32 is a cylinder, 32a is a piston shaft, and 33 is a stopper. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A vertically moving table having a table guided vertically by a static pressure air slide, and a vertically movable table mounted on the vertically moving table. And a pulling member for growing the crystal by rotating the raw material while rotating it in a state supported by static pressure and growing the crystal.