Chemical apparatus and process disinfecting – deodorizing – preser – For deodorizing of – or chemical purification of – or... – With means exposing gas to electromagnetic wave energy or...
Reexamination Certificate
2001-03-26
2002-05-14
Warden, Sr., Robert J. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
For deodorizing of, or chemical purification of, or...
With means exposing gas to electromagnetic wave energy or...
C422S243000, C422S186040, C422S186010, C055S299000, C055S299000
Reexamination Certificate
active
06387333
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas purifying system, and more particularly, to a gas purifying system for effectively eliminating contaminating materials emanating from production equipment, equipment operators, and the ambient production environment in general.
2. Description of the Related Art
Particulate contamination during the semiconductor device manufacturing process greatly increases the likelihood of device failure. In particular, a highly purified gaseous atmosphere is required to control fine particles (i.e., atomic or molecular sized gaseous contaminating particles) on or near the surface of a semiconductor substrate. The sources of these contaminating particles are numerous, including the production equipment, the equipment operators, the ambient production environment, and the process gases, acids and bases, organic contaminants, etc., used in manufacturing a semiconductor device.
Purification systems are thus very important for the productivity and proper operation of a semiconductor device, and many methods are employed to control or eliminate contaminating particles.
For example, semiconductor devices are manufactured and managed in a clean room. In the clean room, various filters, water showering systems (WSS), etc. are employed to collect and remove the contaminating materials. Generally, about 400-600 filters are installed in a single clean room.
Filters employed in the clean room are typically active carbon filters or ion exchange filters (IEF). The active carbon filter is manufactured by pulverizing active carbon, compression molding the pulverized active carbon, and then coating a material thereon which attracts or collects a specific contaminating component. The active carbon filter is utilized for removing ozone, organic materials, SOx, NOx, etc. The IEF filter is manufactured by combining fiber with various chemical functional groups and is utilized for collecting ions such as ammonium cation.
The WSS produces minute water droplets formed by spraying water through nozzles. Floating dust within an air stream collides with these water droplets and become adsorbed, and then they are eventually removed.
FIGS. 1A and 1B
are schematic diagrams of a conventional WSS in which
FIG. 1A
is a side view and
FIG. 1B
is a partial top view taken along a line 1-1′ in FIG.
1
A. The conventional WSS includes the following: a water spraying system
10
having a plurality of nozzles
14
a,
14
b,
14
c,
etc., for producing minute water droplets; a crash plate
20
for separating the water droplets into minute droplets having a smaller size than the water droplets; an eliminator
30
with which the water droplets collide and then fall downward; and a tank
50
for collecting the falling water droplets and storing this collected water until the collected water is provided to the water spraying system
10
. In operation, potentially contaminated in-flowing air Ai is introduced into the WSS through the water spraying system
10
, it passes through the crash plate
20
and the eliminator
30
along a path designated by the arrows, and it is then exhausted out as clean out-flowing air Ao.
The water spraying system
10
is provided with a plurality of vertically extending water transferring pipes
12
a,
12
b,
12
c
, . . .
12
n,
and a plurality of nozzles
14
a,
14
b,
14
c,
. . .
14
n,
configured in at least one vertical line on each of the water transferring pipes. A water transferring pipe supporter
16
supports the water transferring pipes
12
a,
12
b,
12
c,
. . .
12
n.
Water supplied from the tank
50
by means of a pump
60
moves upward along the water transferring pipes
12
a,
12
b,
12
c,
. . .
12
n,
and then is rapidly sprayed through the nozzles
14
a,
14
b,
14
c,
. . .
14
n.
In this embodiment the nozzles are arranged in two vertical columns on the water transferring pipes, preferably with a predetermined angle larger than 90° separating the columns. The size of the sprayed water droplets can be controlled, and is determined by the size of the nozzles
14
a,
14
b,
14
c
. . .
14
n,
and the water pressure. Preferred droplet size is about 100 &mgr;m or less for optimal effect in removing the contaminating material.
The water droplets sprayed from the nozzles
14
a,
14
b,
14
c
. . .
14
n,
impact the crash plate
20
, which comprises a plurality of vertically extending long plates
22
a,
22
a′
,
22
b,
22
b′,
. . .
22
n,
22
n′
so that the water droplets are divided into smaller droplets. When the size of the water droplets becomes smaller, the overall effective surface area of the group of droplets becomes larger. Thus, the adsorbing effect of the droplets for the contaminating material increases. For each of the water transferring pipes (e.g.,
12
a
), two corresponding plates (e.g.,
22
a,
22
a′
) are installed. The plates
22
a,
22
a′
,
22
b,
22
b′,
. . .
22
n,
22
n′
are supported by a crash plate supporter
26
and are provided perpendicular to the direction of the sprayed water from the nozzles (e.g.,
14
a
) as shown in FIG.
1
B.
Water droplets, which have passed through the crash plate
20
, collide with the eliminator
30
. The eliminator
30
is manufactured from a plastic material or SUS (stainless steel) and preferably has a porous plate shape. The eliminator
30
comprises a plurality of eliminating plates
32
a,
32
b,
32
c,
. . .
32
n,
as shown in FIG.
1
B. The eliminating plates
32
a,
32
b,
32
c,
. . .
32
n,
are installed so that the openings through the adjacent eliminating plates are offset, and are supported by an eliminator supporter
36
. In such an arrangement, water droplets containing contaminating material passing through a front eliminating plate
32
a
might collide with a rear eliminating plate
32
b
or
32
c.
Since it is positioned under the water spraying system
10
, the crash plate,
20
and the eliminator
30
, the tank
50
collects the water droplets containing the contaminating materials, which have collided with the crash plate
20
and the eliminator
30
. The collected water is stored in the tank
50
until the water is provided to the water spraying system
10
again. The recirculation time is determined by periodically measuring the electrical resistance of the water in the tank
50
. When the water contains a large amount of contaminating material, the resistance thereof increases. Generally, a predetermined amount of water is injected while the same amount of water is exhausted out to keep the resistance of the water at a constant value.
By utilizing the above described filtering and WSS gas purifying systems, various contaminating components including floating dust and aqueous contaminating materials can be advantageously removed.
However, non-aqueous contaminating materials and organic contaminating materials cannot be satisfactorily removed. In particular, when a large amount of gas passes rapidly, the contaminating material contained in the gas also passes rapidly, which minimizes the amount of time the contaminating material can impact the water droplets. In addition, for sub-micron particles, the removing efficiency of the non-aqueous and organic gas contaminating materials and minute particles is poor.
Indeed, among the causes for deterioration in production yields of semiconductor devices, it is believed that 80% or more are caused by minute particle contamination. As the integration density of semiconductor devices increases, tighter controls on gaseous contaminating materials is required. Furthermore, since the lifetime of the above-described filters and WSS is limited, replacement of the filters, and the maintenance/upkeep of the nozzles and eliminator are required.
Research is being conducted on gas purifying systems utilizing ultraviolet light. According to this principle, photoelectrons generated by an ultraviolet ray attach themselves to the minute particles in the air, and this combination is then collected by an electrode. Japanese Laid-Open P
Choi Jae-Heung
Hwang Jung-Sung
Kim Tae-Ho
Lee Soon-Young
Conley Sean E.
Volentine & Francos, PLLC
Warden, Sr. Robert J.
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