Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2000-11-16
2002-10-08
Ghyka, Alexander (Department: 2812)
Coating apparatus
Gas or vapor deposition
With treating means
C118S712000, C438S758000, C432S036000
Reexamination Certificate
active
06461438
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-328795, filed Nov. 18, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a thermal treatment method of heating or cooling a substrate such as, for example, an LCD substrate or a semiconductor wafer or the like, and a thermal treatment unit.
In processes of manufacturing semiconductor devices, the photolithography is performed on a surface of a substrate such as, for example, a semiconductor wafer (described as “a wafer” hereinafter) or the like. In the photolithography, a sequence of processes are performed in which a predetermined pattern is exposed on the wafer after a resist solution is applied on the surface thereof and subsequently developing is performed thereon.
In such coating and developing processes, heat treatment is performed on the wafer if necessary after the resist coating, the exposing and the developing, and thereafter cooling processing is subsequently performed to cool the wafer in a state of a high temperature, to a certain degree.
A heat treatment unit for performing heat treatment has a heating plate in which a heater is embedded. The wafer is placed on the heating plate and subjected to heat treatment by heat from the heating plate. A temperature sensor is attached to the heating plate so that a temperature of the heating plate can be monitored. A signal from the temperature sensor is inputted to a controller for controlling a temperature of the heater based on the sensor signal sent from the sensor.
A cooling unit for performing cooling treatment has a cooling plate in which a Peltier element is embedded. The wafer at a high temperature after the heat treatment is placed on the cooling plate and subjected to cooling treatment by cold energy of the cooling plate. A temperature sensor is attached to also the cooling plate so that a controller controls a temperature of the Peltier element based on a signal from the temperature sensor similarly to the above-described heating plate.
Now, a state of the temperature of the heating plate when the wafer is heated up to a predetermined temperature is shown in FIG.
22
. In a graph in
FIG. 22
, a horizontal axis indicates heating time [sec.] and a vertical axis indicates the temperature of the heating plate [° C.]. When the wafer is placed on the heating plate, the heating plate loses an amount of heat to the wafer and its temperature is lowered, as shown by Graph Line “k” in
FIG. 22
(time t
1
to t
2
in FIG.
22
). The controller, which recognizes the drop in temperature by the temperature sensor, increases an amount of electric power to the heater to start heat treatment. At this time, the temperature of the heating plate overshoots since heating by the heater is abruptly performed (time t
2
to t
3
in FIG.
22
). Subsequently, the controller, which recognizes the overshoot by the temperature sensor, decreases the amount of electric power to the heater to lower the temperature of the heating plate (time t
3
to t
4
in FIG.
22
). After passing through the processes as described above, the temperature of the heating plate becomes stable. Incidentally, PID control, in which a proportional element, an integral element, and a derivative element are added, is adopted for the controller so that excess properties can be improved by reducing a deviation to a minimum.
Next, a state of a change in temperature of the cooling plate when the wafer after the heat treatment is cooled to, for example, 23° C. is shown in FIG.
23
. In a graph in
FIG. 23
, a horizontal axis indicates cooling time [sec.] and a vertical axis indicates the temperature of the cooling plate [° C.]. As shown by Graph Line “
1
” in
FIG. 23
, the temperature of the cooling plate maintains 23° C. before the wafer is placed thereon. Then, when the wafer at a high temperature is placed on the cooling plate, the cooling plate receives an amount of heat from the wafer and the temperature of the cooling plate is raised (time t
1
to t
2
in FIG.
23
). The controller, which recognizes the rise in temperature by the temperature sensor, subsequently increases an amount of electric power to the Peltier element to start cooling treatment. At this time, the temperature of the cooling plate undershoots 23° C. since cooling by the Peltier element is abruptly performed (time t
2
to t
3
in FIG.
23
). Thereafter, the controller, which recognizes the undershoot by the temperature sensor, decreases the amount of electric power supplied to the Peltier element to raise the temperature of the cooling plate (time t
3
to t
4
in FIG.
23
). After passing through the processes as described above, the temperature of the cooling plate is stabilized to maintain 23° C. Also in this case, PID control is adopted for the controller so that excess properties can be improved.
Incidentally, the wafer having a temperature of, for example, 23° C. (a room temperature) undergoes heat treatment at 200° C. in so-called prebaking (PREBAKE) for the sake of heating-removal of a resist solvent in a resist after resist coating, the wafer having a temperature of 23° C. undergoes heat treatment at 90° C. in post-exposure baking (PEB), and the wafer having a temperature of 23° C. undergoes heat treatment at 30° C. in postbaking (POSTBAKE) performed after developing treatment.
Conventionally, however, in spite of variations in heating temperatures under various heat treatments as described, one type of various data which are inputted to a proportional operation coefficient, integral time and derivative time among control parameters are used in PID control computed by a controller.
Therefore, although there is no particular problem when the wafer is heated to a specific temperature, when the wafer undergoes heat treatment at a temperature different from the specific temperature, a deviation is increased and excess properties are deteriorated since the controller cannot cope with the different temperature, thereby lengthening recovery time of the heating plate, more specifically, time which is required to stabilize the heating plate at a predetermined temperature. As a result, there is a risk of causing a reduction in a throughput.
In addition, there is a case where heating temperatures are different corresponding to recipes, for example, even in the same PEB, and also there is a risk that the recovery time is lengthened.
Similarly also in cooling treatment, various data inputted to control parameters are fixed to one pattern in PID control computed by a conventional controller. Therefore, although there is no particular problem when the wafer, which is heated to a specific temperature, is cooled to 23° C., when the wafer, which is heated to a temperature different from the specific temperature, is placed on a cooling plate, the controller cannot cope with the different temperature, thereby lengthening recovery time of the cooling plate and causing a reduction in a throughput.
BRIEF SUMMARY OF THE INVENTION
The present invention is made in view of the aforesaid points and its object is to shorten recovery time in heat treatment or cooling treatment.
In light of the above object, according to a first aspect of the present invention, a heat treatment unit of the present invention comprises a heating plate on which a substrate is placed, a heating element capable of heating the heating plate at different temperatures, a temperature controller which control a temperature of the heating element according to a transfer function, and a control parameter changing section which changes a setting of a control parameter in the transfer function at each of the different temperatures.
According to a second aspect of the present invention, a heat treatment unit of the present invention comprises a heating plate on which a substrate is placed, a heating element capable of heating the single heating plate at different temperatures,
Harada Koji
Ookura Jun
Ghyka Alexander
Tokyo Electron Limited
LandOfFree
Heat treatment unit, cooling unit and cooling treatment method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat treatment unit, cooling unit and cooling treatment method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat treatment unit, cooling unit and cooling treatment method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2993040