Electric heating – Heating devices – With power supply and voltage or current regulation or...
Reexamination Certificate
2002-10-02
2004-10-26
Jeffery, John (Department: 3742)
Electric heating
Heating devices
With power supply and voltage or current regulation or...
Reexamination Certificate
active
06809300
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
This invention relates generally to a temperature adjusting system for adjusting temperature of a predetermined space by controlling temperature of a medium such as a gas, fluid or solid, for example. More particularly, the invention concerns a non-interference type temperature adjusting control system, and an exposure apparatus having such a control system.
An apparatus for reducing a circuit pattern formed on an original, such as a reticle through a projection optical system and for transferring the same to a substrate such as a semiconductor wafer, is called a semiconductor exposure apparatus. Usually, it is called a stepper. Recently, a semiconductor exposure apparatus in which an exposure process is carried out by moving a reticle stage carrying thereon a reticle and a wafer stage carrying thereon a semiconductor wafer, in opposite directions in synchronism with each other, and at a predetermined speed ratio, has been developed, and it is called a scanner. In such semiconductor exposure apparatuses, the apparatus structure as a whole is accommodated in a temperature controlled chamber.
In recent years, in order to meet requirements for improved productivity of an exposure apparatus, such as a semiconductor exposure apparatus, positioning mechanisms such as an original stage (e.g., a reticle stage) and a substrate stage (e.g., a wafer stage), for example, are made to be driven at higher speeds. This causes increased heat generation in actuators for driving these stages. It disturbs the light path of an interferometer used for the positioning of the stage and, consequently, it results in deterioration of the positioning precision. Further, since heat generation causes expansion/contraction in size of various structural components, this deteriorates the measurement precision. For these reasons, improvements in precision of temperature control for a chamber for accommodating an exposure apparatus have been desired.
Conventionally, in order to keep a predetermined temperature inside a chamber, a gas is once cooled and then it is re-heated by using a temperature adjuster. After a desired temperature is reached, the gas is supplied into a space where a constant temperature is to be maintained. Here, the gas may be air, nitrogen gas, or helium, for example. Now, air is taken as an example of an operative gas. However, the following description applies to nitrogen gas or helium as an operative gas.
First, referring to
FIG. 14
, a conventional temperature control system will be explained.
FIG. 14
shows a structure of a temperature control system of a known type, wherein denoted at
501
is an air blower for discharging air cooled by a cooling unit (not shown), and denoted at
502
is a re-heating heater for re-heating the air supplied from the blower
501
. Denoted at
503
is a duct for introducing the re-heated air, and denoted at
504
is temperature measuring means for measuring the temperature at an air blowing outlet port. Denoted at
505
is temperature controlled air, and denoted at
506
is a temperature controlled space, which depicts an approximate space where the temperature is going to be controlled. This space
506
accommodates therein a stage
507
as a positioning mechanism of a semiconductor exposure apparatus, and a laser interferometer
508
as position measuring means for positioning control of the stage
507
.
In the temperature controlled space
506
, since the stage
507
is driven with acceleration and deceleration at high speeds, heat is generated by actuators, not shown. This causes deviation of the temperature inside the space
506
from a predetermined value. The temperature measuring means
504
measures the temperature of the air at the air blow outlet port, and an output thereof is applied to a temperature controller
509
whereby an appropriate compensation signal is produced. This compensation signal is applied as an input to a driver
510
for controlling the amount of voltage application to the re-heating heater
502
, such that the voltage application to the heater
502
is controlled and, thus, the heating amount to the cool air supplied from the blower
501
is controlled. As a result, air being controlled to a constant temperature can be supplied into the space
506
from the air blow outlet port. The temperature controller
509
can be used for temperature control in a plant, for example, and it has a function for mainly accomplishing PID compensation wherein, as well known in the art, P means proportion, I means integration and D means differentiation.
The temperature controlling system shown in
FIG. 14
is based on such a concept that temperature controlled air
505
should be produced and the space
506
should be filled with the same. There is a heat generating source inside the space
506
as an external disturbance factor, and it may cause deviation of the temperature inside the space
506
from a desired temperature. Since, however, the temperature measuring means
504
is hidden inside the duct
503
rather than being exposed in the space
506
, the temperature measuring means
504
does not sense a temperature change inside the space
506
immediately. Namely, in this system, air
505
having been controlled at a designated temperature is consistently supplied into the temperature-deviated space
506
, thereby to correct the deviated temperature. In other words, the space
506
is controlled at a designated temperature by substituting the air inside the space
506
, having a temperature deviated from a desired temperature, by air having been temperature controlled and kept at a designated temperature. Thus, it should be noted that in the structure of
FIG. 14
the space
506
is not directly temperature controlled. Any external disturbance produced inside the space
506
is never directly detected, and it means that the function for suppressing a temperature change due to external disturbance is very poor. For this very reason, conventionally, an additional mechanical structure, such as a shield for encircling the space
506
, is used to prevent external disturbance from entering the space
506
.
For better understanding of the above, an analogy is introduced here.
FIG. 15
shows a mechanical system in which, by driving a motor
511
, an inertial load
513
connected thereto through a spring
512
is rotationally driven. This mechanical system is functionally equivalent to the temperature control system described above.
In
FIG. 15
, the motor
511
is controlled on the basis of an output of a sensor
514
. More specifically, in terms of a rotational speed or rotational displacement, the state of the motor
511
is detected, and the detection result is fed back to a controller
515
. Thus, while the motor shaft may be controlled accurately, the inertial load
513
connected to the motor through the spring
512
is left uncontrolled. Therefore, even if a torque external disturbance
516
is applied to the inertial load
513
and the rotational speed or rotational displacement of the inertial load
513
changes, it is possible that the rotational speed or rotational displacement at the motor
511
side is unchanged.
The temperature controlling structure shown in
FIG. 14
can be regarded as being an equivalent to this. Specifically, the state detection at the motor
511
side by the sensor
514
corresponds to the temperature detection at the air blow outlet port by the temperature measuring means
504
, and the torque external disturbance applied to the inertial load
513
corresponds to the external disturbance entering the space
506
. Therefore, as in the case of
FIG. 15
, wherein the rotational speed or displacement of the inertial load
513
may change relative to the motor
511
shaft in response to the torque external disturbance applied to the inertial load
513
, it is clear in
FIG. 14
that, when external disturbance influences the space
506
, the temperature in the space changes relative to the air temperature as controlled at the location of the temperature measuring means
Makita Yoshinori
Wakui Shinji
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Jeffery John
LandOfFree
Temperature adjusting system in exposure apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Temperature adjusting system in exposure apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Temperature adjusting system in exposure apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3316933