Coating apparatus – Gas or vapor deposition
Reexamination Certificate
2000-02-24
2002-12-03
Lund, Jeffrie R. (Department: 1763)
Coating apparatus
Gas or vapor deposition
C261S076000, C261S108000, C261S111000, C261S117000, C261S127000, C261S146000, C261S147000
Reexamination Certificate
active
06488774
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a trap apparatus, and more particularly to a trap apparatus optimum for trapping a material gas discharged from a vapor deposition apparatus for depositing in a vapor phase thin films of high-dielectric or ferroelectric such as barium/strontium titanates on substrates.
2. Description of the Related Art
Recently, in the semiconductor manufacturing industry, the integration of integrated circuits has been improved remarkably, and the research and development activities of DRAM are being intensively carried out in anticipation of gigabit order DRAMs which will replace current megabit order DRAMs. The capacitor element having a large capacity per unit area is needed to produce such DRAMs. As a dielectric thin-film material for producing elements having such a large capacity per unit area, in place of silicon oxide or silicon nitride having dielectric constant less than 10, a metallic oxide film material such as tantalum pentaoxide (Ta
2
O
5
) having dieelectric constant of approximately 20, or barium titanate (BaTiO
3
) or strontium titanate (SrTiO
3
) or barium strontium titanate having dielectric constant of approximately 300 is considered to be a promising thin-film material. Further, a ferroelectric material having a higher dielectric constant is also considered to be a promising thin-film material.
In addition to the above, as a wiring material, copper which has a value of resistance lower than aluminum and a superior resistance against electromigration is considered to be a promising material. As a material for gate insulating film, BiVO, Bi
4
Ti
4
O
12
, YMnO
3
, ZnO, ZnS, and CdS are considered to be a promising material. As an electrode material having a perofskite structure, SrRuO
3
, BaRuO
3
, IrO, and CaRuO
3
are considered to be a promising material. As a material for a barrier layer or a buffer layer, MgO, Y
2
O
3
, YSZ, and TaN are considered to be a promising material. As a superconductivity material, La—Ba—Cu—O, La—Sr—Cu—O, Y—Ba—Cu—O, Bi—Sr—Ca—Cu—O, Tl—Ba—Ca—Cu—O, and Hg—Ba—Ca—Cu—O are considered to be a promising material.
As a process for depositing thin films of such material, a chemical vapor deposition (CVD) process is expected to have a good prospect.
FIG. 6
shows a chemical vapor deposition apparatus for depositing thin films of high-dielectric or ferroelectric such as barium/strontium titanates. The vapor deposition apparatus comprises a vaporizer
10
for vaporizing a liquid material, a hermetically sealable reaction chamber
14
disposed downstream of the vaporizer
10
and connected to the vaporizer
10
through a material gas passage
12
, and a vacuum pump
18
disposed downstream of the reaction chamber
14
and provided in an evacuation passage
16
. An oxidizer gas pipe
20
for supplying an oxidizer gas such as oxygen is connected to the reaction chamber
14
.
In the vapor deposition apparatus having the above structure, a substrate W is placed on a stage
22
for holding and heating the substrate W, and a mixture of material gas and oxidizer gas is ejected over the substrate W from nozzles
26
of a gas supply head
24
while keeping the substrate W at a predetermined temperature, thereby depositing a thin film on a surface of the substrate W. In this case, it is necessary to supply the material gas stably to the substrate W in the reaction chamber
14
. The material gas is produced by liquidizing Ba(DPM)
2
, Sr(DPM)
2
or the like which is solid at room temperature, mixing the liquidized substance with organic solvent such as tetrahydrofuran (THF), and vaporizing the obtained mixture by the vaporizer
10
.
Gases discharged from the reaction chamber
14
contain unconsumed material and reaction by-product having a high sublimation temperature, and hence the unconsumed material and the reaction by-product are solidified during pressure rise and deposited on the interior of the vacuum pump
18
, resulting in a malfunction of the vacuum pump
18
. In order to prevent this deposition on the interior of the vacuum pump, as shown in
FIG. 6
, a trap apparatus
30
is provided at the upstream side of the vacuum pump
18
in the evacuation passage
16
to remove components, in the discharged gases, having a high sublimation temperature and a low vapor pressure. The pipe interconnecting the reaction chamber
14
and the trap apparatus
30
is provided with a temperature adjusting device
28
comprising a mantle heater or the like in the same manner as the material gas supply passage
12
.
Conventionally, as shown in
FIG. 7
, the trap apparatus
30
comprises a trap unit
34
having a spiral baffle plate
32
for forming a spiral fluid passage, a trap container
36
for housing the trap unit
34
, an inlet pipe
38
connected to the upper end of the trap container
36
, and an outlet pipe
40
connected to the bottom of the trap container
36
. The trap apparatus
30
is connected to the evacuation passage
16
by quick couplings
42
a
and
42
b
. The trap apparatus
30
has a cooling medium flow passage
44
, at the central part thereof, through which a cooling medium cooled to a temperature lower than the condensing temperature of the components, to be trapped, having a low vapor pressure flows. Thus, the components having a low vapor pressure in the discharged gases which have entered the trap container
36
through the inlet pipe
38
are trapped and removed by the trap unit
34
while the discharged gases flow along the baffle plate
32
, and hence only the components having a high vapor pressure are led to the vacuum pump
18
through the outlet pipe
40
and the evacuation passage
16
(see FIG.
6
).
However, in this trap apparatus, the components having a low vapor pressure such as the unconsumed material are condensed to become powdery substances in the trap container, and the produced powdery substances are gradually deposited on the surface of the trap unit. These deposited solid substances, if counterflow occurs, or the supply amount from the upstream side is abruptly decreased or is stopped under change of conditions in the evacuation system, form particles which will flow into the reaction chamber and deposit on the substrate, resulting in deteriorating quality of a produced film.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a trap apparatus which can reliably trap components having a low vapor pressure in gases discharged from a processing apparatus such as a chemical vapor deposition apparatus and prevent the trapped components from being scattered around.
According to a first aspect of the present invention, there is provided a trap apparatus disposed downstream of a vacuum process chamber. The vacuum process chamber is for processing a substrate. The trap apparatus is for trapping a component having a low vapor pressure contained in a gas discharged from the vacuum process chamber. The trap apparatus comprises a trap container for introducing the gas discharged from the vacuum process chamber, and a cooling device provided in the trap container for cooling the gas to a temperature equal to or lower than a condensing temperature of a gas component which is contained in the gas and easily liquidized.
According to the present invention, the discharged gas introduced into the trap container is cooled by the cooling device, and a gas such as a solvent gas (gas generated from solvent by vaporization), which is contained in the material gas and easily liquidized, is condensed in the trap container, and thus the condensed substances are contained in deposited substances in the trap container. Therefore, the deposited substances in the trap container are moistened, and hence adhesion between the deposited substances and the inner surface of the trap container and cohesion of the deposited substances are heightened. Thus, the deposited substances are prevented from being removed from the inner surface of the trap container and the like, thus preventing generation of particles.
According to a second aspect of the pre
Abe Masahito
Araki Yuji
Horie Kuniaki
Nakada Tsutomu
Ebara Corporation
Lund Jeffrie R.
Wenderoth , Lind & Ponack, L.L.P.
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