Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2000-02-23
2002-09-03
Bueker, Richard (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S715000
Reexamination Certificate
active
06444042
ABSTRACT:
This application claims the benefit of Korean Application No. 6359/1999 filed Feb. 25, 1999, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chemical vapor deposition device, and particularly, to a gas injection system for a chemical vapor deposition device. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for improving process performance by facilitating temperature control at a shower head unit and by restricting generation of particles causing contamination, and evenly providing gas at a surface of a wafer.
2. Description of the Related Art
In order to form a BST [(Ba,Sr)TiO
3
] thin film, gas phases of barium, strontium, titanium, and oxygen are provided at a surface of a wafer positioned in a chamber, and chemical reactions of the gases.
Constitution of a conventional CVD device is described with reference to the accompanying drawings.
FIG. 1
is a schematic view illustrating the conventional CVD device including a chamber
10
having a space of a predetermined size, a heater casing
20
provided in the chamber
10
, a heater
30
provided in the heater casing
20
, a wafer
40
positioned at the upper portion of the heater casing
20
, and a shower head unit
70
engaged with a gas providing pipe and having a nozzle plate
60
for injecting gases on the wafer
50
. Additionally, an exhaust pipe (not shown) engaged with the chamber
10
is provided for externally discharging the gases from the chamber
10
. There are also provided an exhaust pipe (not shown) and a vacuum pump (not shown) for producing a vacuum inside the chamber
10
.
The shower head unit
70
for a gas injection will now be explained in more detail with reference to
FIGS. 2 through 5
.
FIG. 2
is a partial cross-sectional view illustrating the shower head unit
70
.
FIGS. 3 and 4
are a front view and a cross-sectional view respectively illustrating the nozzle plate
60
positioned at the bottom portion of the shower head unit
70
.
FIG. 5
is an enlarged view of portion II in FIG.
4
.
At the upper portion of the shower head unit
70
, a heater
71
is provided for maintaining the gases (barium, strontium, titanium and oxygen) provided through the gas providing pipe
50
at an elevated temperature. In addition, a buffer space
72
is formed inside the shower head unit
70
in order for the gases to be widely diffused. The nozzle plate
60
for evenly injecting the gases on the wafer
40
is provided at the bottom portion of the buffer space
72
. Here, a plurality of nozzles
61
are formed at the nozzle plate
60
in order to evenly inject the gases on the wafer
40
.
Operation of the conventional CVD device will now be described.
Firstly, the wafer
40
is positioned at the upper portion of the heater casing
20
in the chamber
10
by a wafer transfer (not shown). The chamber
10
is under a vacuum condition maintained by a vacuum pump (not shown). Thereafter, the gases (barium, strontium, titanium, and oxygen) having a predetermined temperature are introduced into the shower head unit
70
through the gas providing pipe
50
and widely diffused in the buffer space
72
.
Here, the gases diffused in the buffer space
72
of the shower head unit
70
are maintained at a predetermined temperature by the heater
71
. The diffused gases are injected onto the wafer
40
through the plurality of nozzles
61
of the nozzle plate
60
. On the other hand, a temperature of the wafer
40
positioned at the upper portion of the heater casing
20
is increased to approximately 500° C. by the heater
30
. Accordingly, the gases in the chamber
10
, such as barium, strontium, titanium, and oxygen are mixed and reacted one another. As a result, a resultant material is deposited at the surface of the wafer
40
, thereby forming a BST thin film.
The heater
30
has a higher temperature than the wafer
40
in order to increase its temperature. However, in the gas injection system for the conventional CVD device, a radiant heat of the heater
30
is transmitted into the shower head unit
70
, thus increasing a temperature of the shower head unit
70
. As a result, the temperature of the gases become higher than a desired temperature. Therefore, the gases are partially reacted in the buffer space
72
of the shower head unit
70
. Also, a chemical reaction does not start on the wafer but in the shower head unit
70
, thereby generating particles that are a main cause of contamination. As a result, it reduced the process performance.
In order to overcome such a disadvantage, the nozzle plate
60
of the shower head unit
70
must be positioned separately from the wafer
40
by a predetermined distance. However, such a modification creates another problem because it is difficult to keep the size of the CVD device at a minimum.
SUMMARY OF THE INVENTION.
Accordingly, the present invention is directed to a gas injection system for chemical vapor deposition device that substantially eliminates one or more of problems due to limitations and disadvantages of the related art.
Another object of the present invention is to provide a gas injection system for a chemical vapor deposition (CVD) device which can restrict generation of particles causing contamination by facilitating a temperature control of a shower head unit in regard to gases sensitive to the temperature, and which can improve process performance.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a gas injection system for a chemical vapor deposition (CVD) device includes a gas providing pipe providing gases into the system, a shower head-unit coupled to the gas providing pipe for evenly injecting the gases on a wafer, and a temperature control unit coupled to the shower head unit for controlling a temperature of the shower head unit.
In another aspect of the present invention, a gas injection system for a chemical vapor deposition (CVD) device includes a gas providing pipe providing gases into the system, a shower head unit coupled to the gas providing pipe for evenly injecting the gases on a wafer, a heating system coupled to the shower head unit for controlling a temperature of the shower head unit, a cooling system coupled to the heating system for controlling a temperature of the heating system, and a temperature sensor coupled to the shower head unit.
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: 4993358 (1991-02-01), Mahawili
patent: 5156820 (1992-10-01), Wong
patent: 5275976 (1994-01-01), Moslehi
patent: 5446824 (1995-08-01), Moslehi
patent: 5551985 (1996-09-01), Brors
patent: 5595606 (1997-01-01), Fujikawa
patent: 5624498 (1997-04-01), Lee
patent: 5647911 (1997-07-01), Vanell
patent: 5653806 (1997-08-01), Van Buskirk
patent: 5728223 (1998-03-01), Murakami
patent: 5792269 (1998-08-01), Deacon et al.
patent: 5878191 (1999-03-01), Miyashita
patent: 5935337 (1999-08-01), Takeuchi
patent: 5950925 (1999-09-01), Fukunaga
patent: 6110289 (2000-08-01), Moore
Webster's Third New International Dictionary, Unabridged, Merriam-Webster Inc., 1993, page 1173.
Eiki Tanigawa
Kim Chang Jae
Park In Jae
Yang Seung Yoon
Yoon Jong Woo
Bueker Richard
Hyundai Electronics Industries Co,. Ltd.
Morgan & Lewis & Bockius, LLP
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