Heating – Work chamber having heating means – Work chamber having gaseous material supply or removal...
Reexamination Certificate
1998-06-02
2001-04-17
Ferensic, Denise L. (Department: 3749)
Heating
Work chamber having heating means
Work chamber having gaseous material supply or removal...
C432S144000, C432S152000, C432S192000, C118S715000
Reexamination Certificate
active
06217319
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to semiconductor manufacturing devices, and more particularly, to a semiconductor manufacturing device for baking a wafer in the process of photolithography.
2. Description of the Background Art
In the process of photolithography in the manufacture of semiconductor devices, resist is applied on a wafer and patterned into a prescribed shape. At the time, the resist is subjected to various baking processes including dehydration bake (DH), adhesion bake (AD), pre-bake (PB), post-exposure bake (PEB), and post-development bake (PDB).
FIG. 4
shows an example of a semiconductor manufacturing device, a hot plate unit
1
capable of performing the baking processes as described above. Referring to
FIG. 4
, hot plate unit
1
has a bake plate
3
provided in a chamber
8
and a cover
2
. Bake plate
3
is continuously placed in a heated state by a heater, and held at a prescribed temperature. Cover
2
has an outlet
6
and an inner wall face
2
c
. Hot plate unit
1
is provided with an inlet
9
for taking in gas into chamber
8
.
A method of baking using hot plate unit
1
having the above-described structure will be now described. A wafer
7
is placed on bake plate
3
in chamber
8
by a robot arm and the like. At the time, wafer
7
and bake plate
3
are brought into a close contact state or a point-contact state (proximity bake). Chamber
8
is filled with air, DA (Dry Air), N
2
and the like. In the state, wafer
7
is subjected to a baking processing for a prescribed time period. During the period, the gas is constantly let out from outlet
6
provided at cover
2
at 2 to 3 L (liter)/min. After wafer
7
has been thus baked, wafer
7
is taken out from chamber
8
, and the baking completes.
As described above, conventional hot plate unit
1
is devised to improve the displacement efficiency by providing outlet
6
and inclining the inner wall face
2
c
of cover
2
. The amount of displacement is about as large as
2
to 3 L/min in order to restrict crystallization of a sublimate in chamber
8
.
While such a countermeasure to sublimation is important, wafer
7
should be evenly baked as well. This is because how evenly wafer
7
has been baked affects the uniformity of line width or the like on a main surface
7
a
after patterning.
FIG. 5
shows a distribution of hole sizes (a distribution within a wafer surface) in the main surface
7
a
of wafer
7
after a hole size reducing process using a thermal flow of resist by conventional hot plate unit
1
. As shown in
FIG. 5
, hole sizes in the central portion of wafer
7
are extremely larger than those in the other parts. This shows that wafer
7
could hardly be evenly baked by conventional hot plate unit
1
. This is probably because conventional hot plate unit
1
as described above does not take much into account the effect of air flow within chamber
8
or radiant heat from cover
2
. Hence, such conventional hot plate unit
1
cannot be used for a process sensitive to heat treatment, a hole size reducing process in particular.
SUMMARY OF THE INVENTION
The present invention is directed to a solution to the above-described problem. It is an object of the invention to provide a semiconductor manufacturing device which permits wafer
7
to be evenly baked.
A semiconductor manufacturing device according to the present invention directed to baking a wafer, in one aspect, includes a chamber, a heater portion, a cover, an inlet/outlet, and a member having a ventilation hole. The heater portion is placed within the chamber, on which a wafer is placed. The cover has an inner wall face opposite to a main surface of the wafer placed on the heater portion, and the main surface of the wafer and the inner wall face of the cover are separated from each other at a fixed distance. The inlet/outlet is provided at a position opposite to the main surface of the wafer to let in or let out gas. The member having the ventilation hole is provided between the inlet/outlet and the wafer such that the distance from the main surface of the wafer is identical to the distance between the inner wall face of the cover and the main surface of the wafer.
As described above, by fixing the distance between the inner wall face of the cover and the main surface of the wafer, radiant heat may be evenly caused at the main surface of the wafer opposite to the inner wall surface by rays radiated from the inner wall face of the cover. Furthermore, by positioning the member between the inlet/outlet and the wafer at a level almost the same as that of the inner wall face of the cover, radiant heat may be caused on the surface of the wafer opposite to the member by rays radiated from the member. As a result, radiant heat may be generated evenly on the main surface of the wafer, which permits the wafer to be evenly baked. In addition, the member has a ventilation hole through which an appropriate amount of gas may be supplied/exhausted. Thus, crystallization of a sublimate within the chamber may be restricted.
Gas is preferably externally supplied into the chamber. The gas is sent into the chamber via the cover. The cover preferably has a gas path for increasing the temperature of the gas sent into the chamber.
The cover has such a gas path that gas warmed at the time of passing through the path may be sent into the chamber. Thus, the wafer can be prevented from being cooled by the gas coming into the chamber from the outside. This also contributes to even baking of the wafer.
The cover is preferably provided with a first gas path communicating with the inlet/outlet, and a second gas path communicating with the first gas path through the chamber. The second gas path is preferably provided along the first gas path and the inner wall face of the cover.
Thus providing the second gas path along the first gas path and the inner wall face of the cover permits gas allowed into the second gas path to be heated by gas allowed out through the first path and the inner wall face of the cover if the second path is used for example as an inlet path. Thus, gas passing through the second gas path may be heated without additionally providing a heater device. Note that the first gas path and the second gas path may be equally advantageously used as an inlet path and an outlet path, respectively.
The above-described member is preferably a plate having evenly provided ventilation holes. The circumferential portion of the member is preferably connected with the inner wall face of the cover.
Thus evenly providing ventilation holes at the member permits appropriate gas supply/displacement. Thus, an appropriate air flow may be generated in the chamber, and thermoconductivity may be improved while effectively restricting crystallization of a sublimate. Furthermore, connecting the circumferential portion of the member with the inner wall face of the cover permits the member fixed at a position as high as the inner wall face of the cover. Thus, radiant heat may be almost evenly generated at the main surface of the wafer.
In another aspect of the invention, the semiconductor manufacturing device includes an displacement control valve to control the displacement at a level not less than 0.1 L/min and not more than 1 L/min.
Thus controlling the displacement at the level not less than 0.1 L/min and not more than 1 L/min can restrict a variation of hole sizes in the hole size reducing process as shown in FIG.
3
. As a result, setting the displacement within the above-described range could largely contribute to even baking of the wafer. Note that if the displacement is set lower than 0.1 L/min, it would be difficult to forcibly generate an air flow within the chamber, which could lead to deposition of a sublimate within the chamber. The displacement is therefore preferably not less than 0.1 L/min.
The semiconductor manufacturing device according to this aspect preferably has a chamber and a cover. The cover is provided with an outlet and gas paths formed around the outlet to let gas into the chamber. A p
Miyagi Tadashi
Saito Takayuki
Yamada Yoshiaki
Ferensic Denise L.
McDermott & Will & Emery
Mitsubishi Denki & Kabushiki Kaisha
Wilson Gregory A.
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