Ion implanting system

Details Ion implanting system Ion implanting system

2002-06-10

2003-11-25

Wong, Don (Department: 2821)

Electric lamp and discharge devices: systems

Discharge device load with fluent material supply to the...

Electron or ion source

C315S111810, C315S111710, C118S7230VE, C118S7230FI, C118S7230FE, C417S901000

Reexamination Certificate

active

06653792

ABSTRACT:

CROSS REFERENCE
This application claims the benefit of Korean Patent Application No. 2001-37071, filed on Jun. 27, 2001, under 35 U.S.C. §119, the entirety of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ion implanting system, and more particularly, to a vacuum pump for an ion implanting system.
2. Description of Related Art
An ion implanting system includes a source chamber, an ion beam chamber, a main chamber, and a load lock chamber. Theses chambers include at least one vacuum pump for creating a vacuum atmosphere therein, respectively.
A conventional ion implanting system includes at least one cryo pump, usable as a vacuum pump, for creating a vacuum atmosphere in a main chamber and at least one cryo pump for creating a vacuum atmosphere in the load lock chamber. Further, the at least one cryo pump for creating a vacuum atmosphere in the load lock chamber is usually smaller in size and operated at higher revolutions per minute (rpm) than the at least one cryo pump for creating a vacuum atmosphere in the main chamber. Hence, the cryo pump(s) for creating a vacuum atmosphere in the load lock chamber is contaminated with impurities more easily than the cryo pump(s) for creating a vacuum atmosphere in the main chamber.
A cryo pump creates a vacuum atmosphere in a chamber by condensing and removing gas molecules that contact a cooling portion refrigerated by liquid hydrogen or liquid helium. When an inside of the cryo pump becomes saturated so that an inside temperature of the cryo pump rises, the cryo pump exhausts impurities therein during a regeneration operation. The regeneration operation includes inputting high temperature nitrogen gas into the cryo pump to vaporize the condensed impurities and outwardly exhaust the vaporized impurities.
In other words, when a cryo pump is contaminated with the impurities, an inside temperature of the cryo pump rises. When the inside temperature exceeds a set temperature, an error state is indicated, whereby an operation of the cryo pump is stopped. In order to clean an inside of the cryo pump, an operator initiates a regeneration operation.
Since the cryo pump for creating a vacuum atmosphere in the load lock chamber is contaminated with impurities more easily than the cryo pump for creating a vacuum atmosphere in the main chamber, the cryo pump for creating a vacuum atmosphere in the load lock chamber requires more frequent regeneration operations.
FIG. 1
is a block diagram illustrating a conventional ion implanting system. The ion implanting system of
FIG. 1
includes a source chamber
10
, an ion beam chamber
12
, a main chamber
14
, load lock chambers
16
-
1
to
16
-
3
, a cryo pump controller
18
, a compressor
20
, a roughing pump
22
, cryo pumps
24
to
32
, and valves V
1
to V
14
.
The source chamber
10
ionizes gas molecules externally injected. The ion beam chamber
12
accelerates ions input from the source chamber
10
to generate an ion beam. The main chamber
14
irradiates the ion beam from the ion beam chamber
12
into a semiconductor wafer (not shown). The load lock chambers
16
-
1
to
16
-
3
load/unload the semiconductor wafer into/from the main chamber
14
. The cryo pumps
24
to
30
create a high vacuum atmosphere in the main chamber
14
. The cryo pump
32
creates a high vacuum atmosphere in the load lock chambers
16
-
1
to
16
-
3
and vacuum lines VL
2
to VL
5
. The valve V
5
opens or closes a channel between the source chamber
10
and the ion beam chamber
12
. The valve V
6
opens or closes a channel between the ion beam chamber
12
and the main chamber
14
. The valves V
1
to V
4
open or close channels between the main chamber
14
and the cryo pumps
24
to
30
, respectively. The valves V
7
to V
9
open or close channels between the main chamber
14
and the load lock chambers
16
-
1
to
16
-
3
, respectively. The value V
10
opens or closes a channel between the cryo pump
32
and the vacuum line VL
2
. The cryo pump controller
18
applies control signals for controlling the cryo pumps
24
to
32
, respectively, and generates an error signal in response to temperature sensing signals “a” to “e”, respectively, applied from the cryo pumps when a temperature within the cryo pumps
24
to
32
exceeds a set temperature. The compressor
20
generates control voltages STARTA and RUNA to the cryo pumps
24
to
32
in response to the control signals applied from the cryo pump controller
18
. STARTA and RUNA are shown in
FIG. 1
as the control voltages for controlling the cryo pump
32
.
A vacuum pumping operation of the ion implanting system of
FIG. 1
is described below.
Semiconductor wafers (not shown) are loaded into cassettes (not shown) of the load lock chambers
16
-
1
to
16
-
3
. The valves V
11
to V
14
are opened, and the valve V
10
is closed. A low vacuum atmosphere is created in the load lock chambers
16
-
1
to
16
-
3
and the vacuum lines VL
1
to VL
5
by the roughing pump
22
. The roughing pump
22
performs a pumping operation to maintain a pressure of about 10
−2
torr.
The valve V
11
is closed, and the valves V
10
and V
12
to V
14
are opened. A high vacuum atmosphere is created in the load lock chambers
16
-
1
to
16
-
3
and the vacuum lines VL
2
to VL
5
by the cryo pump
32
. A high vacuum atmosphere is created such that compressed helium gas from the compressor
20
into the cryo pump
32
reduces a temperature of a gas to be refrigerated. The roughing pump
22
performs a pumping operation to maintain to a pressure of about 10
−6
torr to about 10
−5
torr. The cryo pump
32
performs a pumping operation to create a high vacuum atmosphere in the load lock chambers
16
-
1
to
16
-
3
and the vacuum lines VL
2
to VL
5
when the compressor
20
applies the control voltages STARTA and RUNA to the cryo pump
32
in response to the control signal applied from the cryo pump controller
18
.
The valves V
7
to V
9
arranged between the main chamber
14
and the load lock chambers
16
-
1
to
16
-
3
are opened, and the cassettes of the load lock chambers
16
-
1
to
16
-
3
that load the semiconductor wafers are placed into the main chamber
14
. Thereafter, an ion implanting process is performed.
However, since the cryo pump
32
for creating a vacuum in the load lock chambers
16
-
1
to
16
-
3
is smaller in size and operates at higher revolutions per minute (rpm) than the cryo pumps
24
to
30
for creating a vacuum in the main chamber
14
, the cryo pump
32
is more easily contaminated than the cryo pumps
24
to
30
.
A temperature sensing diode (not shown) detects whether the cryo pump
32
is contaminated or not. The cryo pump controller
18
receives a temperature sensing signal “a” output from the cryo pump
32
and indicates an error state when a temperature inside the cryo pump
32
exceeds a set temperature, thereby stopping an operation of the ion implanting system. The cryo pump
32
performs a regeneration operation to remove the impurities therein and normal operation may continue.
The regeneration operation is performed as follows: nitrogen (N
2
) gas is input to the cryo pump
32
, and therefore an inside pressure of the cryo pump
32
rises and reaches a set pressure of an attached relief valve (not shown). The relief valve is opened to outwardly exhaust the impurities and the nitrogen gas inside the cryo pump
32
.
As a result, in the conventional ion implanting system, when the inside temperature of the cryo pump
32
exceeds a set temperature, an error occurs, whereupon a regeneration operation should be performed after stopping the ion implanting system. Also, the ion implanting process cannot be continued until the regeneration operation is completed.
As described above, in a conventional ion implanting system, a cryo pump for creating a vacuum atmosphere in the load lock chamber is easily contaminated, and a regeneration operation should be performed often, which lowers the operational performance of the conventiona

Affiliated with

Also associated with

Rating

Ion implanting system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Ion implanting system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ion implanting system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3136630