Fluent material handling – with receiver or receiver coacting mea – Diverse fluid containing pressure filling systems involving... – Gas treatment
Reexamination Certificate
2002-02-21
2004-06-29
Niebling, John F. (Department: 2812)
Fluent material handling, with receiver or receiver coacting mea
Diverse fluid containing pressure filling systems involving...
Gas treatment
C206S711000
Reexamination Certificate
active
06755221
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus. More particularly, the present invention relates to a load port of a semiconductor manufacturing apparatus.
2. Description of the Related Art
FIG. 1
illustrates a typical loading section
100
of a semiconductor manufacturing apparatus at which disk-shaped semiconductor wafers are loaded into the apparatus. The loading section
100
includes a load port (
200
in FIG.
2
), a mini-chamber
110
having a wafer transfer robot
112
and a door opening robot (not shown), and a load lock chamber
120
. A wafer cassette
130
that stores disk-shaped wafers is safely placed by hand or by an automated material handling system (AMHS) onto the load port
200
outside the mini-chamber
110
. A front opening unified pod (FOUP) is widely used as the wafer cassette
130
for wafers that are 300 mm in diameter.
Subsequently, the door opening robot of the mini-chamber
110
opens a door
132
of the wafer cassette
130
. Then the wafer transfer robot
112
transfers the wafers stacked in the cassette
130
into the load lock chamber
110
. The wafers are transferred from the load lock chamber
120
to a process chamber (not shown).
Referring now to
FIG. 2
, the load port
200
onto which the FOUP
130
is placed includes a plurality of kinematic coupling pins
220
and a plurality of sensors
240
arrayed on a flat surface thereof. The FOUP
130
includes grooves (not shown) that receive the kinematic coupling pins
220
when the FOUP
130
is placed on the load port
200
. The sensors
240
contact a portion of a bottom surface of the FOUP
130
to sense whether the FOUP
130
is properly resting on the load port
200
.
If the sensors
240
do not sense that the FOUP
130
is positioned properly on the load port
200
, a subsequent process is not executed. That is, the process in which the door opening robot opens the door
132
of the FOUP
130
and the wafer transfer robot
112
transfers wafers from the FOUP
130
into the load lock chamber
120
, will not be carried out.
In the load port
200
shown in
FIG. 2
, the kinematic coupling pins
220
substantially contact the FOUP
130
to support it and the sensors
240
only sense whether the FOUP
130
is properly resting on the load port
200
. Therefore, if a foreign object or substance lies on the sensors
240
, the sensors
240
can incorrectly sense that the FOUP
130
is properly situated on the load port
200
. In addition, the sensors
240
are not as tall as the kinematic coupling pins
220
. Therefore, even when the FOUP
130
is resting properly on the kinematic coupling pins
220
, a bottom surface of the FOUP
130
may not sufficiently contact the sensors
240
. In this case, the sensor
240
will not perform properly, i.e., will not correctly sense the presence of the FOUP
130
.
Still further, the load port
200
can not determine whether wafers are stored in the wafer cassette. An empty wafer cassette
130
can sometimes be erroneously transferred onto the load port
200
. In this case, even though the wafer cassette
130
is properly placed on the load port
200
, a subsequent process is initiated. Accordingly, a processing error occurs.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome the problems described above.
More specifically, one object of the present invention is to provide a load port that can accurately sense whether a wafer cassette has been properly placed thereon in preparation for the loading of wafers into a chamber of a manufacturing apparatus.
Another object of the present invention is to provide a load port which can discriminate whether a wafer cassette placed thereon contains any semiconductor wafers.
In order to achieve the above objects, the load port of the present invention includes a support member, a plurality of kinematic coupling pins projecting upwardly from the support member, and a plurality of sensors integrated with the coupling pins.
The sensors are operable to sense for the presence of the bottom of the cassette and thereby determine whether the wafer cassette is resting properly on the load port. The contact of each sensor, except at an upper end thereof, is embedded in a respective kinematic coupling pin. The upper end of the sensor protrudes from the kinematic coupling pin. Preferably, at least three kinematic coupling pins and corresponding sensors are arrayed on the support member so as to balance a wafer cassette that is placed properly thereon. The sensors may be photo sensors or on-off sensors (switches). Alternatively, the sensors may be weight-detecting sensors that make use of piezoelectric elements. The wafer cassette has grooves in the bottom surface thereof, and the grooves receive the kinematic coupling pins and the sensors when the wafer cassette properly rests on the load port.
According to the present invention, it is possible to accurately sense whether the wafer cassette is situated properly on the support member of the load port and/or to discriminate whether the wafer cassette contains any wafers, because the sensors are integrate with the kinematic coupling pins which support the cassette directly. Thus, the reliability of the semiconductor manufacturing process is enhanced.
Another object of the present invention is to provide a method of loading wafers into a chamber of a semiconductor apparatus that prevents processing errors from occurring.
To achieve this object, the method of the present invention entails detecting for the presence of the bottom of the cassette at a plurality of sites located on the upper surface of the support member, and measuring the load exerted by the cassette. If the bottom of the cassette is detected as being present at each of the detection sites, then the cassette is determined to be resting properly for the transfer of wafers therefrom. And, if the load exceeds a predetermined value corresponding to the weight of a cassette, then it is determined that the cassette contains a wafer(s). A control signal is issued to initiate the manufacturing process only once these conditions are established is. In particular, the door of the cassette is opened, and a robot is commanded to transfer wafers from the cassette into a chamber of the manufacturing apparatus.
The manufacturing process is thus never initiated when the cassette is situated improperly on the load port or not at all, and/or when the cassette is situated properly but does not contain wafers.
REFERENCES:
patent: 5988233 (1999-11-01), Fosnight
patent: 6250869 (2001-06-01), Krocker
patent: 6398032 (2002-06-01), Fosnight
Jeong Gyu-Chan
Kim Ki-Sang
Niebling John F.
Stevenson André C
Volentine & Francos, PLLC
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