JPH07123034B2 - Ion implanter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention electrically scans an ion beam and
The present invention relates to a so-called hybrid scan type ion implanter that mechanically scans a wafer in a direction orthogonal to the direction.

[Background technology]

Prior art examples of this type of ion implantation apparatus are shown in FIG. 4 and FIG.

This ion implantation apparatus electrically scans the ion beam 2 in the X direction (for example, the horizontal direction) to form a parallel beam and guides the parallel beam into the implantation chamber 4, and at the same time, in the implantation chamber 4, the wafer 6 is orthogonal to the X direction in the Y direction. Having a structure for mechanically scanning in a direction (for example, a vertical direction), a holder 8 for holding a wafer 6 in the implantation chamber 4, and a holder drive for scanning the holder 8 in the implantation chamber 4 in the Y direction. And device 10.

The holder driving device 10 includes a vacuum seal bearing 12 provided on a side surface portion of the injection chamber 4, a main shaft 14 penetrating the bearing 12 in the X direction, and an output shaft connected to an end of the main shaft 14 outside the injection chamber. Reversible direct drive motor 16 and the reversible direct drive motor 18 mounted so as to be substantially orthogonal to the injection chamber inner side end of the main shaft 14, the output shaft of this direct drive motor 18 It is equipped with an arm 22 mounted so as to be orthogonal to each other, and a chemical-reversal type direct drive motor 24 mounted so as to be substantially orthogonal to this arm 22, so that it is substantially orthogonal to the output shaft of this direct drive motor 24. The holder 8 described above is attached to. Further, vacuum seal portions 20 and 26 are provided at the tip portions of both motors 18 and 24, respectively, in order to vacuum seal the output shafts thereof so that the motors can be used in vacuum.

During ion implantation, as shown in FIG.
Lower arm 22 from 0 ° (vertically up) position by
For example, the horizontal position (90 °) is assigned to a range of 70 ° (ie,
It makes a reciprocating turn in the range of 55 ° to 125 °). As a result, the wafer 6 held by the holder 8 is mechanically scanned in the Y direction in a shape of an arc while facing the ion beam 2.

The motor 24 is used to keep the postures of the holder 8 and the wafer 6 constant when the arm 22 is rotated as described above. The motor 16 is used to drive the holder 8 in the implantation state and the horizontal state for handling the wafer 6.

[Object of the Invention]

The torque due to the weight of the arm 22 and the like when the arm 22 is turned as described above is shown by a curve A in FIG. This torque becomes a sin curve, and if no measures are taken,
Since this becomes the load torque applied to the motor 18 as it is, a large load torque of T ₁ is applied to the motor 18 at the maximum. In this case, a negative load is applied to the motor when the arm 22 is turned horizontally (90 °) in the descending direction (125 ° direction), and a positive load is applied when the arm 22 is rotated in the ascending direction (0 ° direction). Become.

Therefore, if it is left as it is, the capacity of the motor 18 becomes large, and the motor 18 and eventually the entire ion implantation apparatus become large.

On the other hand, there is an idea to attach a counterweight 28 to the opposite side of the arm 22 as shown by a chain double-dashed line in FIG. 4, but in this case as well, the injection chamber 4 and the like must be enlarged. Therefore, the entire ion implantation apparatus becomes large.

Therefore, it is a main object of the present invention to provide an ion implantation apparatus capable of reducing the load torque applied to the above-described motor for rotating the arm by means other than the normal counterweight. .

[Means for achieving the following]

In order to achieve the above-mentioned object, an ion implantation apparatus of the present invention has a main body part including a compressed air type actuator having a rotary output shaft, a compressed air source and compressed air from the compressed air source to be an actuator of the main body part. A compressed air type counter balancer including a compressed air supply unit including a pressure reducing valve for supplying the compressed air is provided, and an output shaft of an actuator of the counter balancer is connected to a turning center of the arm.

[Action]

According to the above configuration, when the arm is rotated by the motor, the actuator of the counter balancer is also interlocked.

At this time, if compressed air is supplied from the compressed air supply unit to the actuator, the volume inside the actuator decreases and the internal pressure rises when the arm swings in the downward direction, so the compression amount is increased accordingly. Air is exhausted from the pressure reducing valve.

On the contrary, when the arm turns in the ascending direction, the volume inside the actuator increases and the internal pressure decreases, so that compressed air is supplied via the pressure reducing valve by a corresponding amount.

By such an action, the torque of the counter balancer is
Ideally, it is constant, but in reality, it is within a predetermined narrow range.

The difference between the torque of this counter balancer and the torque of the arm etc. becomes the load torque applied to the motor. By setting the torque of the counter balancer near the maximum torque value by the arm etc., the load torque applied to the motor can be drastically reduced. Can be made smaller.

〔Example〕

FIG. 1 is a diagram partially showing an ion implantation apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing details of the counter balancer in FIG. The same parts as those of the preceding example shown in FIGS. 4 and 5 are designated by the same reference numerals, and the differences from the preceding example will be mainly described below.

In this embodiment, there is provided a compressed air type counter balancer 30 having a general portion 40 attached to the back surface portion of the motor 18 as described above and a compressed air supply portion 50 arranged outside the injection chamber 4. ing.

As shown in FIG. 2, the main body 40 has, as a compressed air type actuator, two pneumatic cylinders 42a and 42b arranged in this example so as to face each other. The pistons 44a, 44b in both pneumatic cylinders 42a, 42b have racks 46
a and 46b are connected to each other, and both racks 46a and 4b
A common pinion 48 is meshed with 6b, and a reversible output shaft 49 is connected to this pinion 48.

As shown in FIG. 1, the main body 40 has arms 22
It is attached to the mounting plate 62 on the back of the direct drive motor 18 that turns the
Through the center of 18 the arm 22 is connected to the center of rotation 22a of the arm 22 using a connecting plate 64.

In this example, the compressed air supply unit 50 has a compressed air source 52, a solenoid valve 54, and a pressure reducing valve 56, and the compressed air from the compressed air source 52 is reduced to a predetermined pressure by the pressure reducing valve 56. , Both pneumatic cylinders 42a, 42b of the main body 40 via the piping 60
Is supplied to.

The opposite side of the pneumatic cylinders 42a, 42b to which the compressed air is supplied (that is, the racks 46a, 46b side) communicates with the inside of the motor 18, for example, around the output shaft 49,
The inside of the motor 18 also communicates with the atmospheric pressure side through the inside of the main shaft 14.

According to the above configuration, when the arm 22 is swung by the motor 18 as described in FIG. 5 and the like, the pneumatic cylinder 42 of the main body 40 of the counter balancer 30 is output via the output shaft 49 and the like.
a and 42b also work together.

At this time, the compressed air supply unit 50 to the both pneumatic cylinders 42
When compressed air is supplied to a and 42b, when the arm 22 (that is, the holder 8) swings in the descending direction, the pistons 44a and 4b
Although the volume of the pneumatic cylinders 42a, 42b decreases due to the movement of 4b to increase the internal pressure, the pressure reducing valve 56 acts to keep the pressure on the secondary side constant, so that the piston 44
Compressed air is discharged from the pressure reducing valve 56 by the volume compressed by a and 44b.

On the contrary, when the arm 22 turns in the upward direction, the volume inside the pneumatic cylinders 42a, 42b increases and the internal pressure tries to decrease.However, the pressure reducing valve 56 reduces the pressure on the secondary side in the same manner as above. Since it acts to keep constant, the compressed air source 52 is increased by an amount corresponding to the increased volume from the compressed air source 52 through the pressure reducing valve 56.
Is supplied with compressed air.

Due to such an action, the torque of the counter balancer 30 ideally becomes constant. For example, double pneumatic cylinder
By properly selecting the pressure of the compressed air supplied to 42a and 42b, the torque of the counter balancer 30 is, as shown by the straight line B in FIG.
The average torque T ₂ of the torque (curve A) by the arm or the like in the range of 125 ° can be obtained.

However, the turning speed of the arm 22 is not constant and changes depending on the injection conditions. If this speed increases, the supply and discharge of compressed air by the pressure reducing valve 56 will be delayed, so both pneumatic cylinders
The pressure in 42a and 42b is not constant, but fluctuates within a predetermined narrow range. Therefore, the torque of the counter balancer 30 is also
In practice, for example as shown in the third oval curve B shown by a broken line in FIG. 'Varies within a narrow range of T ₁ through T _3.

The difference between the torque of the counter balancer 30 (curve B ') and the torque of the arm 22 or the like (curve A) becomes the load torque applied to the motor 18 during the injection operation. Thus, for a set torque, such as FIG. 3, the maximum load torque (T ₁ -T ₃₎ according to the motor 18, and the such counter balancers
It can be made significantly smaller than the maximum load torque T ₁ when 30 is not provided (for example, about 1/5 or less).

The injection operation is completed, and the arm 22 is moved from the 55 ° position to 0
When returning to the position of 0 °, the solenoid valve 54 provided in the compressed air supply unit 50 is closed and the motor 18 is rotated in the direction of 0 °, and the compressed air trapped in the pneumatic cylinders 42a, 42b of the counter balancer 30 is compressed. Is forcibly expanded, and the torque of the counter balancer 30 at this time approximates the torque (curve A) by the arm 22 and the like, as shown by the curve C in FIG. the load torque can be within the torque (T ₁ -T _3).

By providing the counter balancer 30 in this manner, the load torque applied to the motor 18 can be reduced to reduce the capacity and size of the motor 18, and the counter weight 28 as shown in FIG. Since it is not necessary, the ion implantation apparatus can be downsized as a whole.

In addition, the load fluctuation on the motor 18 is reduced and the arm
The movement of 22 is smoothed, and the mechanical scanning of the holder 8 and the wafer 6 is also smoothed, so that the implantation characteristics (eg, implantation uniformity) for the wafer 6 are also improved.

Further, when the main body 40 of the counter balancer 30 is attached to the opposite side of the main shaft 14 to the motor 18 as in this embodiment, the main body 40 also functions as a counter weight for the weight of the motor 18, etc. Direct drive motor
The effect of reducing the load torque of 16 is also obtained.

It should be noted that the pneumatic cylinder of the main body 40 may be a single large cylinder, but it is possible to reduce the size of the main body 40 by arranging two small cylinders facing each other as in this embodiment. it can.

Further, in the main body 40, as a compressed air type actuator, instead of the pneumatic cylinders 42a, 42b as described above,
A rotary actuator such as a pneumatic motor that directly rotates the output shaft 49 may be used.

〔The invention's effect〕

As described above, according to the present invention, since the compressed air type counter balancer is provided, it is possible to reduce the load torque applied to the motor that rotates the arm, and to reduce the capacity and size of the motor. It is possible to reduce the size of the ion implantation apparatus.

In addition, the load fluctuation applied to the motor is reduced, the movement of the arm is smoothed, and the mechanical scanning of the holder and the wafer is smoothed, so that the implantation characteristic for the wafer is also improved.

[Brief description of drawings]

FIG. 1 is a diagram partially showing an ion implantation apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing details of the counter balancer in FIG. FIG. 3 is a diagram showing examples of various torques. FIG. 4 is a diagram partially showing an example of the ion implantation apparatus which is the background of the present invention. FIG. 5 is a view of the device shown in FIG. 4 as seen from the rear side of the arm. 2 ... Ion beam, 6 ... Wafer, 8 ... Holder,
18 …… Direct drive motor, 22 …… Arm, 22a
...... Rotation center part, 30 ...... Compressed air type counter balancer, 40 ...... Main body part, 42a, 42b ...... Pneumatic cylinder (actuator), 49 ...... Output shaft, 50 ...... Compressed air supply part,
56 ... Pressure reducing valve, 60 ... Piping.

Claims (1)

[Claims] 1. A wafer is mechanically moved in a Y direction orthogonal to the X direction by electrically scanning an ion beam in the X direction and rotating an arm having a holder for holding a wafer by a reversible motor. In an ion implantation apparatus configured to scan in a horizontal direction, a main body including a compressed air type actuator having a rotary output shaft, a pressure reducing valve for reducing the pressure of a compressed air source and compressed air from the compressed air source And a compressed air supply unit including a compressed air supply unit, the output shaft of the actuator of which is connected to the center of rotation of the arm.