Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2000-11-10
2002-10-22
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S726000, C118S727000
Reexamination Certificate
active
06467427
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to an evaporation system. More particularly, the present invention relates to a supplier of evaporation source material.
2. Description of Related Art
Thin film deposition technique includes physical vapor deposition and chemical vapor deposition. Physical vapor deposition includes evaporation deposition. Evaporation deposition is carried out by heating an evaporation source to vaporize the source material. The vaporized material forms a saturated vapor that can be deposited back onto a cooler surface as a thin film. Most evaporation system includes an evaporation chamber and a vacuum system for creating a vacuum inside the evaporation chamber. The evaporation chamber also contains an evaporation boat and a wafer holder. The evaporation boat is a container for holding evaporation material normally positioned at the lower end of the evaporation chamber. The evaporation boat can be made from a substance having a high melting point. There is a wafer holder near the top end of the evaporation chamber. The wafer holder is a device for holding a wafer or a substrate that requires thin film deposition. When a suitable current runs through the evaporation boat, the evaporation boat is heated up due to resistor effect. The source material will be heated to a temperature close to its melting point. At such a high temperature, the source material starts to evaporate and saturate the evaporation chamber. The evaporated source particles are deposited onto the cooler wafer surface, thus initiating the thin film deposition process.
FIG. 1
is schematic front view of a conventional evaporation system. As shown in
FIG. 1
, the evaporation system
100
includes an evaporation chamber
102
and a vacuum extraction system
104
. The vacuum extraction system
104
is connected to the evaporation chamber
102
. The components inside the evaporation chamber
102
include an evaporation boat
106
and a wafer holder
108
. The evaporation boat
106
is in the lower portion of the evaporation chamber
102
for holding an evaporation source
110
. The wafer holder
108
is in the upper portion of the evaporation chamber
102
. The wafer holder
108
is a device for holding a wafer
112
requiring thin film deposition. When a suitable current runs through the evaporation boat
106
, the evaporation boat
106
and the source material
110
are heated up to a temperature close to the melting point of the source material
110
. At such a high temperature, the solid source material
110
evaporates into vapor that can be deposited back onto the wafer
112
lying above the evaporation source
110
. However, a conventional evaporation system may run out of evaporation source material in a continuous evaporation process and need replenishing. Time is often wasted in replenishing the evaporation boat
106
because the vacuum inside the evaporation chamber needs to be retreated and then re-established after each replenishing. Thus, source material replenishing not only slows thin film deposition, but also increases operating load of the vacuum extraction system
104
.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a system capable of providing sufficient evaporation source material to last the entire course of a thin film deposition or a long-period continuous deposition. Hence, time-out due to insufficient source material can be prevented and a higher overall productivity can be achieved.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a supplier of evaporation source material. The evaporation system that uses the source material supplier includes an evaporation chamber and a vacuum extraction system. The vacuum extraction system is connected to the evaporation chamber. The source material supplier, a movable evaporation boat and a wafer holder are housed inside the evaporation chamber. The source material supplier is on one of the sidewalls of the evaporation chamber. The wafer holder is in the upper portion of the evaporation chamber. The wafer holder is responsible for holding a wafer requiring thin film deposition. The movable evaporation boat is in the lower portion of the evaporation chamber for holding evaporation source material. The source material supplier includes a revolving cassette wheel and a crucible under the cassette wheel. The revolving cassette wheel is partition by separating plates and an outer casing into a plurality of capsules with each capsule capable of holding a fixed amount of evaporation source material. When the cassette wheel rotates, the lowest capsule can deliver a lump of evaporation source material onto the crucible via a drop hole in the outer casing.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 6340501 (2002-01-01), Kamiyama
patent: 63-58622 (1988-03-01), None
patent: 01-108364 (1989-04-01), None
patent: 02-118071 (1990-05-01), None
patent: 03-126823 (1991-05-01), None
patent: 07-098865 (1995-11-01), None
patent: WO98/50916 (1998-12-01), None
Helix Technology Inc.
Kackar Ram N
Mills Gregory
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