Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1998-09-09
2001-07-10
Jeffery, John A. (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S411000, C392S416000, C392S418000, C118S724000, C118S729000
Reexamination Certificate
active
06259061
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vertical-heat-treatment apparatus for heat-treating a plurality of target substrates, such as semiconductor wafers, all together in a semiconductor processing system. The term “semiconductor processing” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or an LCD substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
Vertical-heat-treatment apparatuses are known as apparatuses for subjecting a number of semiconductor wafers to a predetermined heat treatment all together.
FIG. 9
is a cross-sectional view showing a vertical-heat-treatment apparatus
2
of related arts.
In the heat treatment apparatus
2
, wafers W are vertically stacked with gaps therebetween on a wafer boat
42
of quartz, and then the boat is loaded into a vertical process chamber
8
, so that the wafers are sequentially heat-treated. Since the wafers W have to be maintained at a high process temperature, the wafer boat
42
is loaded in the process chamber
8
while it is mounted on a lid
30
through an insulating cylinder
40
of quartz having a heat-insulating property.
More specifically, when the wafers W are loaded in the process chamber, they are first stacked on the wafer boat
42
. Then, the wafer boat
42
is mounted on the insulating cylinder
40
, and is moved up therewith into the process chamber
8
through an opening
24
by activating an elevating mechanism
26
. Then, the opening
24
is airtightly closed by the lid
30
.
The wafers W on the wafer boat
42
are heated and kept at a predetermined process temperature by a main heater
12
arranged around the process chamber
8
. However, since the opening
24
for the wafer boat
42
should not be heated to a high temperature, the heat-insulating cylinder
40
is used. A temperature gradient is formed in the insulating cylinder
40
, such that the temperature gradually decreases from the process temperature to the temperature of the opening
24
.
The insulating cylinder
40
has a thermal capacity larger than the wafers W and requires a long time to be heated and become thermally stable. For this reason, the process cannot be started until the insulating cylinder
40
has a stable temperature, thereby lowering the throughput. The period of time, until the process chamber becomes thermally stable at the predetermined temperature, is called a temperature recovering time.
During the process, the insulating cylinder
40
has a stable temperature between the process temperature and the temperature of the opening
24
. The insulating cylinder
40
hardly faces any part of the main heater
12
, and thus is supplied with a flow of heat less than that to the wafers W. Consequently, it takes a long time for the insulating cylinder
40
and the lower wafers to become thermally stable. Further, the lower wafers are thermally affected by the insulating cylinder
40
.
In order to solve these problems, several dummy wafers, which are different from wafers to be processed, may be mounted on the lower levels of the wafer boat. Even this method, however, is not sufficient to solve the problems, i.e., a long period of time up to attainment of thermal stability and a thermal ill-effect on the lower wafers.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a vertical-heat-treatment apparatus in a semiconductor processing system, which can shorten the heating time necessary for target substrates to achieve a stable temperature.
It is another object of the present invention to provide a vertical-heat-treatment apparatus in a semiconductor processing system, which can present a high thermal uniformity in the vertical direction within a process chamber.
According to a first aspect of the present invention, there is provided a vertical-heat-treatment apparatus for heat-treating a plurality of target substrates all together in a semiconductor processing system. The apparatus comprises a process chamber for receiving the target substrates, the process chamber having a port at its bottom end; a lid for opening and closing the port; a holder for holding the target substrates to be vertically stacked with gaps therebetween in the process chamber, the holder being loaded and unloaded into and from the process chamber through the port; a main heater disposed around the process chamber, for heating an atmosphere in the process chamber through a side wall of the process chamber; and a compensation heater disposed under the lid, for heating the target substrates on the holder from below through the lid.
According to a second aspect of the present invention, there is provided a vertical-heat-treatment apparatus for heat-treating a plurality of semiconductor wafers all together. The apparatus comprises a process chamber for receiving the wafers, the process chamber having a port at its bottom end; a lid for opening and closing the port; a holder for holding the wafers to be vertically stacked with gaps therebetween in the process chamber, the holder being loaded and unloaded into and from the process chamber through the port, while being supported by the lid; an elevating mechanism for vertically moving the lid along with the holder; a supply mechanism for supplying a process gas into the process chamber; an exhaust mechanism for exhausting and setting the process chamber at a vacuum; a main heater disposed around the process chamber, for heating an atmosphere in the process chamber through a side wall of the process chamber; and a compensation heater disposed under the lid, for heating the wafers on the holder from below through the lid, the compensation heater being vertically moved along with the lid by the elevating mechanism.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
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Jeffery John A.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tokyo Electron Limited
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