Photocopying – Projection printing and copying cameras – With temperature or foreign particle control
Reexamination Certificate
2001-11-02
2004-03-02
Nguyen, Henry Hung (Department: 2851)
Photocopying
Projection printing and copying cameras
With temperature or foreign particle control
C355S053000
Reexamination Certificate
active
06700641
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for controlling the temperature in the chamber of an exposure apparatus used in a photolithography process for producing a semiconductor element, an imaging element (CCD, etc.), a liquid crystal display element, a thin film magnetic head, etc., and to an exposure apparatus operated in the method.
2. Description of the Related Art
When a semiconductor element, etc. is produced, an exposure apparatus which transfers a pattern of a reticle as a mask to each shot area on the wafer to which resist is applied as a photosensitive substrate directly or through a projective optical system. Conventionally, an exposure apparatus (stepper) of a contraction projection type in a step-and-repeat system has been widely used as an exposure apparatus. However, a projective exposure apparatus in a step-and-scan system for synchronously scanning the reticle and the wafer for the projective optical system for exposure has recently arrested attention.
FIG. 1
shows the general configuration of a conventional exposure apparatus.
In
FIG. 1
, for example, a semiconductor element can be formed by overlapping for exposure a multiple-layer circuit pattern on a wafer
6
in a predetermined arrangement. Therefore, in the process of exposing the wafer
6
, it is very important to improve the precision in alignment between the pattern image to be exposed and the existing pattern on the wafer
6
, and the precision in controlling a focus position. Therefore, the exposure apparatus has an isolation room called a ‘chamber’ which is controlled such that the temperature in the exposure apparatus can indicate a constant value, and contains the body of an exposure device including precision parts such as a projective optical system
5
, a stage, etc. The body of the exposure device includes a lighting optical system
2
, a reticle stage
4
for holding and aligning a reticle
3
, the projective optical system
5
, and a wafer holder
7
for holding the wafer
6
, and a wafer stage
8
for aligning the wafer
6
(the wafer holder
7
). The wafer stage
8
is mounted on the floor of the chamber
1
through a frame material
9
. The chamber
1
is mounted on a floor F
1
in a semiconductor factory.
To keep a constant temperature in the chamber
1
, a fluid supply device
11
is provided in the chamber
1
. The fluid supply device
11
is equipped with a cooler
13
and a heater
14
, introduces the air outside or inside the chamber
1
, controls the temperature at a constant value by the effect of the cooler
13
and the heater
14
, and supplies the air into the chamber
1
. The cooler
13
compresses and liquidizes a coolant by a compressor, etc., cools the air with evaporation heat, and has a power source such as a motor, etc. for operating the compressor. Each of the parts such as a stage provided in the chamber
1
is considerably heavy, and requires a high-speed operation, thereby largely heating each of them. Accordingly, the fluid supply device
11
of the chamber
1
is requested to maintain a strong cooling ability, thereby requiring a large compressor of the cooler
13
.
In addition, to prevent fine dust harmful in transferring a circuit pattern from being lead into the chamber
1
, the temperature-controlled air is to be supplied to the chamber
1
through a dust filter
21
such as a HEPA filter (high efficiency particulate air-filter). Therefore, the compressor formed by a pressure fan
12
for a blow and a motor is required to output pressure strong enough to pass the air blow through the dust filter
21
. As a result, a large pressure fan
12
and a large motor are used.
FIG. 2
shows the general configuration of another conventional exposure apparatus.
The exposure apparatus shown in
FIG. 2
is different from the exposure apparatus shown in
FIG. 1
in that the fluid supply device
11
is not mounted in the chamber
1
, but on the external wall of the fluid supply device
11
. Otherwise, they have the same configuration. That is, each of them includes the lighting optical system
2
, the reticle stage
4
for holding and aligning the reticle
3
, the projective optical system
5
, the wafer holder
7
holding the wafer
6
, the wafer stage
8
, the frame material
9
, etc. in a constant temperature room
100
. In addition, the exposure apparatus shown in
FIG. 2
is the same as that shown in
FIG. 2
in that the fluid supply device
11
has the pressure fan
12
, the cooler
13
, and the heater
14
, and blows into the constant temperature room
100
by passing the temperature-controlled air through the dust filter
21
to control the temperature in the chamber
1
. The chamber
1
provided with the fluid supply device
11
is mounted on the floor F
1
in the semiconductor factory.
Furthermore, a device has been developed not only to maintain a constant temperature in the chamber
1
, but also to supply a fluid at a constant temperature to a specific local area (a coil portion of a linear motor, etc.) of an exposure apparatus so that the portion can be more effectively temperature-controlled.
As described above, the conventional exposure apparatus includes the fluid supply device
11
in the chamber
1
or on the external wall of the chamber
1
. As a result, the vibration generated during the operation of the fluid supply device
11
unfavorably lowers the precision in alignment, etc. of the exposure apparatus.
That is, the vibrations generated by the compressor of the cooler
13
forming part of the fluid supply device
11
, and the pressure fan
12
and the motor of the compressor vibrate the wafer stage
8
of the wafer
6
, thereby deteriorating the alignment precision of the wafer
6
, and also the overlapping precision, or vibrate the projective optical system
5
to lower the contrast of the transferred image.
In the conventional exposure apparatus, since the vibration of the fluid supply device for a chamber
1
during the operation has a minor influence with the requested precision taken into consideration, thereby generating a serious problem. However, with an increasing number of smaller semiconductor integrated circuits, etc., the influence of the vibration cannot be ignored because the alignment precision, etc. requested to the exposure apparatus becomes more strict.
SUMMARY OF THE INVENTION
The present invention has been developed based on the above described background, and aims at the first object of providing a method of controlling the temperature in a chamber of an exposure apparatus having the body of an exposure device, and a method of controlling the temperature to reduce an unfavorable influence from the vibration caused by the temperature control. Furthermore, the present invention aims at the second object of providing an exposure apparatus capable of using the above described temperature control method.
In the temperature control method according to the present invention is used with a chamber (
1
) containing the body of an exposure device for transferring a mask pattern to the substrate, a fluid (a gas, a liquid) supplied to the chamber (
1
) from a fluid supply device (
11
,
11
A,
11
B) provided independent of the chamber (
1
) is output, supplied from the fluid supply device (
11
,
11
A,
11
B), and is temperature-controlled before supplied into the chamber (
1
).
With the present invention, the temperature in the chamber can be controlled by controlling the temperature of a fluid supplied to the chamber. Thus, the temperature adjustment equipment, which has been in a chamber as a vibration source, can be mounted outside the chamber, thereby removing the vibration source from the chamber. In addition, since the vibration during the temperature-control of the fluid is hardly transmitted into the chamber, an unfavorable influence such as the deterioration in the alignment precision in the body of the exposure device causing the vibration can be reduced.
Furthermore, in the exposure apparatus according to the present invention, the body of an exposure device for transferrin
Nguyen Henry Hung
Nikon Corporation
Oliff & Berridg,e PLC
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