Radiant energy – Photocells; circuits and apparatus – Signal isolator
Reexamination Certificate
2001-09-27
2004-04-06
Luu, Thanh X. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Signal isolator
C250S492210, C417S044100
Reexamination Certificate
active
06717165
ABSTRACT:
This application relies for priority upon Korean Patent Application No. 2000-63398, filed on Oct. 27, 2000, the contents of which are herein incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
The present invention relates to a device and method for detecting a turbo pump driving state in a tandetron accelerator of an ion implantation device. More particularly, the present invention relates to a device for detecting a driving state of a turbo pump for forming a vacuum state in an accelerator, by which an ion beam is accelerated to implant ions onto a semiconductor wafer. The present invention also relates to a method of operating such a device.
Generally, ion implantation into a wafer is performed under a condition in which an electrically charged atom has a sufficiently large amount of energy to penetrate through the surface of a non-conductive wafer. A tandetron accelerator that accelerates an ion beam includes inside of it a turbo pump for circulating argon gas (Ar) within. The tandetron accelerator is supplied with a high voltage of 650 KV at the stripper portion where the turbo pump is mounted, and the power driving the turbo pump is generally 30V. As a result, the practical externally-supplied voltage is 650 KV+30V. Accordingly, the corresponding power could not be both easily and sufficiently supplied externally while still maintaining a sufficient insulating state of the accelerator.
FIG. 1
is a diagram showing the structure of a conventional device for detecting a turbo pump driving state of a tandetron accelerator by which a sufficient insulating state is maintained.
The device for detecting the turbo pump driving state of a semiconductor ion implantation device according to a prior art includes a motor
10
, a first pulley
12
, a belt
14
, a second pulley
16
, a shaft
18
, a generator
20
, a first cable
22
, a turbo pump
24
, a plurality of beam lines
26
, a stripper
28
, a second cable
30
, a current detecting part
32
, and a current displaying part
34
.
The first pulley
12
is attached to the rotation axis of the motor
10
. The second pulley
16
is attached to the shaft
18
, which is mounted on the rotation axis of the generator
20
. The belt
14
is connected between the first and second pulleys
12
and
16
to transfer the rotation power of the motor
10
to the shaft
18
, to drive the generator
20
. The generator
20
generates a three-phase alternating current, which is sent through the first cable
22
to drive the turbo pump
24
. The turbo pump
24
, in turn, forms a high vacuum environment during an ion implantation process. The stripper
28
is disposed at the center of beam lines
26
and operates to circulate argon gas lest the gas flow out of the beam line
26
. That is, the stripper
28
prevent gas from flowing out of the beam line
26
. The second cable
30
supplies the driving power of the motor
10
to the current detecting part
32
, which measures a current being supplied to the motor
10
. This current is then displayed on the current displaying part
34
.
When the motor
10
starts to rotate in response to an externally-input motor driving signal, the first pulley
12
also rotates. The rotating power of the first pulley
12
is then transferred to the shaft
18
attached to the rotating axis of the generator
20
through the belt
14
and the second pulley
16
. As a result, the generator
20
begins to generate a 3-phase current power to supply to the turbo pump
24
.
At this time, an ion beam proceeds from the right side to the left side of the beam line
26
and is changed from its originally charged state to a positively charged state through a charge-converting procedure. When the ions are radiated through an inlet and collide with argon gas while passing through the stripper
28
, the ions lose their electrons and are charged to become positive ions. Afterwards, the positive ions flow out of an outlet of the stripper
28
opposite the inlet.
The turbo pump
24
maintains a high vacuum state to prevent the argon gas from flowing out of the stripper
28
. In this high vacuum state, the current detecting part
32
connected to the second cable
30
measures the current of the motor
10
and provides it to the current displaying part
34
so that it can be displayed. A user can then confirm the current value displayed on the current displaying part
34
to check whether the turbo pump
24
in the tendetron accelerator is operating normally.
In order to maintain a stable state of the high voltage supplied to the tandetron accelerator, SF
6
gas having an insulating characteristic fills the inner side of the accelerator at a high pressure of 85 psi. Accordingly, when any inner device of the tandetron accelerator fails, it takes about 10 hours to first discharge and later refill the device with this gas in order to repair the device.
However, the conventional device cannot exactly detect the turbo pump driving state of the tandetron accelerator just by measuring the current value being supplying to the motor
10
. As a result, even if the current supplied to the motor
10
is optimal, the turbo pump
24
may not be operated normally, and so argon gas may not be smoothly circulated, thereby causing a change in a charge-converting rate, which can result in a severe process failure.
Korean patent application No. 97-014050 discloses a current measuring device for measuring the current of a turbo pump in accelerator of an ion implantation apparatus in order to solve such a problem. In this Korean Patent application, a current supplied to a turbo pump by a power source is detected and displayed on a current indicator. An interlocking operation is then performed if the turbo pump fails.
However, to do this, electric wires must be laid between the current indicator installed outside of a tandetron tank and the current detecting part installed inside the tandetron tank in order to detect a current supplied to the turbo pump and then display such a current on the current indicator. As a result, an electrically insulation state cannot be maintained between the tandetron tank and the outside.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a device for detecting a turbo pump driving state in a tandetron accelerator by detecting a driving current of the turbo pump in the accelerator. It is also an object of the present invention to provide a method for operating such a device.
Another object of the present invention is to provide a turbo pump driving state detecting device in a tandetron accelerator by which a driving current of a turbo pump in a tendetron accelerator of an ion implantation device is detected and displayed outside of the tendetron accelerator while maintaining the tendetron's insulating state. It is also an object of the present invention to provide a method accomplishing this.
Still another object is to provide a turbo pump driving state detecting device and related method by which a turbo pump driving current is detected and a power supply of an accelerator is cut off when the detected current value is outside of a set range.
In order to accomplish the above objects, a device for detecting a turbo pump drive state in a tandetron accelerator of a semiconductor ion implantation device according to the present invention comprises a turbo pump formed inside of the accelerator; a current detecting part formed inside of the accelerator for detecting a turbo pump driving current applied to the turbo pump, and providing a first electrical signal indicative of the detected turbo pump driving current; an electro-optical converter formed inside of the accelerator for converting the first electrical signal to an optical signal; a photoelectric converter formed outside of the accelerator for converting the optical signal to a second electric signal; an optical cable formed between the electro-optical converter and the photoelectric converter for carrying the optical signal out of the accelerator; and a displaying part formed outside of the accelerator for
Luu Thanh X.
Samsung Electronics Co,. Ltd.
Volentine & Francos, PLLC
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