Clean room and method of remodeling clean room

The present invention is to provide a method of remodeling an existing clean room building into a clean room which satisfies a new required specification. A working room (11) is expanded by removing a wall (29) between the working room (11) and a general passage (30). If a portion of the floor of the working room (11) is not the grated panel structure, such floor portion is formed as the grated panel structure by remodeling and the floor is formed as a perforated free access floor. The whole of the ceiling of the working room (11) is formed as a system ceiling of a frame structure from which a dust-collecting filter whose unit size is 600.times.1200 mm can be made freely detachable if necessary, and a ULPA filter is disposed on a portion which is requested to have a high cleanliness. An air-insulating panel of the same size may be attached to a portion which does not require the dust-collecting filter. An existing air conditioner that has been in use before remodeling is used as the air conditioner as it is.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a clean room used to fabricate
 semiconductor devices and a clean room remodeling method used to remodel
 an existing clean room to provide a clean room with a different
 specification if necessary, and to remodel a general passage or room
 adjacent to a clean room to provide a clean room.
 2. Description of the Prior Art
 Semiconductor devices are extremely sensitive to dusts such as dust
 particles in their fabrication process. Hence, it is customary that
 semiconductor devices are variously processed on the fabrication line in a
 clean room. A clean room generally comprises a working room used to
 fabricate semiconductor devices in actual practice, a supply chamber built
 in a space above the ceiling of the working room to supply the air to the
 working room, a dust-collecting filter for removing dust particles from
 the air supplied to the working room, a grated panel built on the floor of
 the working room to let in the air, a return chamber for returning the air
 from the grated panel through a circulation duct and an air conditioner
 for circulating the air in the sequential order of the supply chamber, the
 working room and the return chamber and which is also used to adjust the
 temperature and the humidity of the air.
 A cleanliness of clean room changes depending upon factors such as an
 integration degree of semiconductor devices manufactured therein. A
 variety of dust-collecting filters are used in response to a required
 cleanliness. As a dust-collecting filter, there are selectively employed a
 HEPA (High Efficiency Particulate Air) filter and a ULPA (Ultra Low
 Penetration Air) filter, etc. Japanese laid-open patent publication No.
 5-149591 and Japanese laid-open patent publication No. 3-177732, for
 example, described such clean room.
 So far a new clean room is required, it is customary that a new clean room
 is built in a vacant lot, including a foundation work. The reason for this
 will be described. As the semiconductor technologies are advanced rapidly,
 requirements concerning the specifications of the new clean room become
 severer than those of the prior art. Hence, it was rather easy to build a
 new clean room including the setting of blow capacities of air
 conditioners and a layout of places in which dust-collecting filters are
 located.
 However, recently, a difficulty in maintaining a labor power and obtaining
 a building lot increases, and a cost of building a clean room occupies a
 large ratio of the entire cost. Therefore, it is expected that it becomes
 more and more difficult to build a semiconductor factory including a clean
 room.
 SUMMARY OF THE INVENTION
 In view of the aforesaid aspect, it is an object of the present invention
 to provide a method of remodeling an existing clean room building into a
 clean room which may satisfy a new required specification.
 In order to attain the above-described object, according to the present
 invention, there is provided a clean room remodeling method for remodeling
 a clean room including an air conditioner and a return chamber located on
 a first floor, a semiconductor fabrication working room located on a
 second floor above the first floor and a supply chamber located in a space
 above the ceiling of the working room to supply the air to the working
 room. This method is comprised of the steps of forming a floor of the
 working room as a grated panel structure, forming a ceiling of the working
 room as a system ceiling, disposing a first dust-collecting filter in a
 ceiling of the working room at its area in which a high cleanliness is
 required partly, disposing a second dust-collecting filter or an
 air-shielding member in ceilings of other areas and using the air
 conditioner as it is.
 According to the present invention, the first dust-collecting filter is a
 ULPA filter and the second dust-collecting filter is a HEPA filter.
 According to the present invention, there is provided a clean room
 remodeling method in which a clean room is expanded by removing a wall
 which partitions a clean room and a room adjacent to the clean room. This
 clean room remodeling method is comprised of a process for setting a first
 detachable partition panel near the wall within the clean room, a process
 for removing the wall, a process for setting a second detachable partition
 panel at a place from which the wall was removed, a process for removing
 the first partition panel, a process for cleaning air in the room and a
 process for joining the clean room and the room by removing the second
 partition panel after the process of cleaning the air in the room is
 completed.
 According to the present invention, the room is a clean room.
 According to the present invention, there is provided a clean room
 remodeling method which is comprised of a process for expanding a clean
 room area by removing a whole-process direction wall between an existing
 clean room and a general room, a process for installing an interbay
 transportation apparatus in an upper portion of an area which was the
 general room, a process for extending a process line provided in the
 direction substantially perpendicular to the whole-process direction, and
 a process for partitioning an area which was a clean room and an area in
 which the interbay transportation apparatus is installed.
 According to the present invention, there is provided a clean room
 remodeling method which is comprised of a process for dividing an existing
 clean room having a plurality of air conditioners into a plurality of
 areas corresponding to the unit of the air conditioner by a partition
 panel, a process for constructing each of divided areas sequentially in
 order to increase a cleanliness, a process for cleaning the air of every
 area whose construction is ended, and a process for removing a partition
 panel when the adjacent area reaches the same predetermined cleanliness.
 According to the present invention, there is provided a method of
 remodeling a general room into a clean room which is comprised of the
 steps of, with respect to an existing building having a first floor, a
 second floor, and a space above a ceiling of the second floor, providing
 an air conditioner and a return chamber on the first floor, forming a
 floor of the second floor as a grated panel structure, disposing a
 dust-collecting filter in the ceiling of the second floor, providing a
 supply chamber in the space above the ceiling of the second floor, joining
 the return chamber and the supply chamber by a duct, and forming the
 second floor as a semiconductor fabrication working room.
 According to the present invention, in a clean room including an air
 conditioner and a return chamber provided on a first floor, a
 semiconductor fabrication working room provided on a second floor above
 the first floor and a supply chamber located in the space above the
 ceiling of the working room to supply the air to the working room, the
 clean room is characterized in that an area having a high cleanliness
 specification within the working room is isolated by a partitioning member
 from other areas, a first dust-collecting filter having a high cleanliness
 specification on the ceiling of a working room space surrounded by the
 partitioning member and a floor of the working room space is formed as a
 grated panel structure.
 According to the present invention, the partitioning member comprises an
 acrylic board processed by an electrostatic preventing treatment.
 Further, according to the present invention, the working room comprises a
 working room space surrounded by the partitioning member and a surrounding
 working room which have a difference of cleanliness level greater than 100
 times therebetween.
 Furthermore, a ceiling of an area other than the area having a high
 cleanliness specification of the working room includes an air-insulating
 member or a second dust-collecting filter whose cleanliness is lower than
 that of the first dust-collecting filter.

DESCRIPTION OF THE PREFERRED EMBODIMENT
 The preferred embodiments of the present invention will hereinafter be
 described with reference to the drawings. FIG. 1 is a plan view of a first
 floor of a clean room before remodeling; FIG. 2 is a plan view of a second
 floor of the clean room before remodeling; FIG. 3 is a cross-sectional
 view taken along the line x--x in FIGS. 1 and 2; FIG. 4 is a plan view
 illustrating the state in which a wall between the working room of a
 second floor of the clean room and a general passage is removed to expand
 the working room to the area which was the general passage before; FIG. 5
 is a cross-sectional view taken along the line y--y in FIG. 4; FIG. 6 is a
 plan view illustrating the state in which a wall between areas A and B is
 removed to enable the entirety to become one working room; and FIG. 7 is a
 plan view illustrating the layout of various treatment equipment in the
 remodeled working room.
 Before remodeling, in the clean room according to this embodiment, as shown
 in FIGS. 1 and 2, areas A and B were partitioned by a wall 10. A working
 room of the area A was a clean room whose cleanliness is relatively high
 (about cleanliness class 100), and a working room of the area B was a
 clean room whose cleanliness was relatively low (about cleanliness class
 10000). Both of the areas A and B comprise a first floor, a second floor
 and a space above a ceiling of the second floor, each of which is
 partitioned by the common wall 10 to provide the areas A and B.
 After the existing clean room shown in FIGS. 1 and 2 is remodeled by a
 clean room remodeling method according to this embodiment, the area A is
 expanded to the areas of a general passage, a general room and other
 portions than the clean room (these room portions will be generally
 referred to as "general room" in this specification), and a cleanliness
 thereof is increased to a class 1 (or higher than cleanliness class 1).
 Further, a continuous space in which the wall 10 for partitioning the
 areas A and B is removed is served as a single clean room, and the area
 which was used as the area B is given the same high cleanliness as that of
 the area A.
 As shown in FIGS. 1 to 3, in the clean room according to this embodiment,
 the first floor includes a return chamber 13 and air-conditioning rooms
 18.sub.1 to 18.sub.3 (when the air-conditioning room is generally referred
 to, it is denoted by reference numeral 18 without suffixes and this
 applies for other elements and parts as well). The air-conditioning rooms
 18.sub.1 to 18.sub.3 include air conditioners 14.sub.1 to 14.sub.3. The
 second floor includes a working room 11 in which a manufacturing line of
 semiconductor devices is installed in actual practice, and a supply
 chamber 16 is located in a space above the ceiling of the second floor.
 Before remodeling, the floor of the area A was partly formed by a grated
 panel 12 as a free access floor in which an area corresponding to an area
 in which a dust-collecting filter 17, which will be described later on, is
 located in the ceiling. Specifically, air supplied from the supply chamber
 16 through the dust-collecting filter 17 to the working room 11 flows
 downwardly in the working room 11 of the second floor and flows through
 the grated panel 12 to the return chamber 13 of the first floor. The air
 in the return chamber 13 is adjusted in temperature and humidity by the
 air conditioner 14, blown by fans of the air conditioner 14 to the upper
 direction through a duct room 15 and reaches the supply chamber 16 in a
 space above the ceiling of the working room. Incidentally, the air
 conditioners 14.sub.1 to 14.sub.3 are treated by a vibration-isolation
 insulating treatment in order to prevent their vibrations from being
 transmitted to the clean room.
 The air supplied to the supply chamber 16 flows through the dust-collecting
 filter 17 located in the ceiling of the working room 11 into the working
 room 11. At that time, dust particles are removed from the air by the
 dust-collecting filter 17. Thus, the flow of clean air partly flowing
 downwardly occurs within the working room 11, and the area for treating
 semiconductor devices is held at a predetermined cleanliness. In this
 embodiment, before remodeling, the dust-collecting filter 17 is located on
 the ceiling of the area in which wafer treatment equipment is located, and
 the dust-collecting filter 17 is located only a portion of the ceiling of
 other areas. Before remodeling, a HEPA filter, for example, is used as the
 dust-collecting filter 17. With respect to the area under the HEPA filter
 and in which the wafer treatment equipment is located, a cleanliness of
 about class 100 was realized.
 As shown in FIG. 2, in the working room 11 of the second floor, one line
 (e.g. line of photolithography process, etc.) is located in the right and
 left direction (single process direction) of the sheet of drawing.
 Accordingly, when wafers are located on any of the lines, wafers are moved
 along the single process direction. In the whole-process direction
 extended in the upper and lower direction of FIG. 2, a plurality of lines
 20.sub.1, 20.sub.2, 20.sub.3, 20.sub.4, 20.sub.5 are located in parallel
 to each other. The length of the whole-process direction is about 100 m.
 Having treated by a predetermined treatment at every line, wafers are
 conveyed to the next line. This convey work was executed by an interbay
 transportation machine 21 located at the left-hand side ceiling of the
 working room 11 (see FIGS. 2 and 3). Therefore, the exchange of wafers
 between each line and the interbay transportation machine 21 is executed
 at stations 22.sub.1 to 22.sub.5 located on the left-hand side end of each
 line.
 Also, as shown in FIGS. 2 and 3, a general passage 30 is adjacent to the
 right-hand side of the existing working room 11 through a wall 29
 extending in the whole-process direction. General rooms 31 (31.sub.1 to
 31.sub.4) are located adjacent to the right-hand side of the passage 30.
 Operators dressed with ordinary clothes may pass or enter the general
 passage 30 and the general rooms 31.
 In this embodiment, the existing clean room shown in FIGS. 1 to 3 is
 remodeled to provide a clean room shown in FIGS. 4 to 6 by a predetermined
 construction, whereby a higher cleanliness is achieved. The second floor
 portion of the area B adjacent to the area A is remodeled into a working
 room having substantially the same cleanliness as that of the working room
 in the area A. To this end, the construction is made by the following
 procedure.
 Initially, as shown in FIG. 4, a wall between the working room 11 and the
 general passage 30 of the second floor and a wall between the general
 passage 30 and the general room 31 are removed to thereby expand the
 working room 11 up to the area which had been so far the general passage
 30 and the general room 31. Concurrently therewith, the interbay
 transportation machine 21 that was located at the upper left end of the
 working room 11 as shown in FIGS. 1 and 3 is installed at the upper
 portion of the area which had been the general passage 30 and the general
 rooms 31.sub.1 to 31.sub.4. Also, on the right-hand end of each line
 (lower portion of the interbay transportation machine 21), there are
 provided stations 22.sub.1 to 22.sub.5 used to interchange wafers between
 the line and the interbay transportation machine 21. As a consequence, as
 shown in FIG. 4, the length of each of the lines 20.sub.1, 20.sub.2,
 20.sub.3, 20.sub.4, 20.sub.5 may be increased in the single-process
 direction longer than those of the past lines (see FIG. 2).
 In this case, according to this embodiment, since the dust-collecting
 filter was not located in the area which had been so far the general
 passage 30 and the general room 31, the area (existing general passage 30
 and the general rooms 31.sub.1 to 31.sub.4) in which the interbay
 transportation machine 21 is newly located and the working room which is
 not remodeled are isolated from each other by a partition panel (not
 shown). In the area which had been the general passage 30 and the general
 room 31 so far, wafers are transported by the interbay transportation
 machine 21 under airtight state so that a cleanliness of this area may be
 about class 1000. Wafers are interchanged through the partition panel by
 the stations. However, when the dust-collecting filter may be located on
 the ceiling of the portion in which the interbay transportation machine 21
 is newly located, the above-mentioned partition panel need not always be
 used.
 Next, of the floor of the working room 11, when there is a portion which is
 not of the grated panel structure, a floor of a portion which is requested
 to become high in cleanliness is formed as a perforated free access floor
 by the grated panel structure. Thus, the air may flow to the return
 chamber of the first floor from the working room 11 at its portion
 requested to have a high cleanliness.
 Further, the whole of the ceiling of the working room 11 is formed as a
 system ceiling of a frame structure. So far the dust-collecting filter is
 fixedly provided only on a portion of the ceiling of the working room so
 far. Thus, if the dust-collecting filter were provided on other portion,
 the dust-collecting filter could not be provided on other portion without
 the frame on which the dust-collecting filter is disposed. On the other
 hand, according to this embodiment, in the case of a construction for
 increasing a class of a cleanliness, the whole of the ceiling is remodeled
 into a system ceiling, whereby a dust-collecting filter in which the unit
 size is 600.times.1200 mm, for example, may be made freely detachable
 according to the need. On the portion which does not require the
 dust-collecting filter, there may be attached an air-insulation panel of
 the same size as an air-insulation member.
 Although the whole of the ceiling is formed as the system ceiling as
 described above, the dust-collecting filter of the same performance need
 not be attached to the whole of the system ceiling. In particular, this
 embodiment assumes that the existing air conditioner of the first floor
 portion is used as it is. If the dust-collecting filter is changed from
 the HEPA filter to the ULPA filter, then a blow capacity of air
 conditioner required per same area increases. Accordingly, if the whole of
 the ceiling is changed from the HEPA filter to the ULPA filter, there is
 then the risk that the capacity of the conventional air conditioner will
 become insufficient. If a necessary amount of air cannot be maintained,
 then a necessary cleanliness also will not be maintained.
 Therefore, according to this embodiment, within a range of the amount of
 air covered by the existing air conditioner, the ULPA filter is provided
 partly within the specified area of the ceiling. To this end, as the
 layout of the working room, according to this embodiment, as shown in FIG.
 7, treatment equipment 50 are located on both sides of one line (shown
 hatched), the treatment equipment 50 on the adjacent lines are installed
 back to back with each other, and the front portion of each treatment
 equipment is faced to a wafer treatment area in which wafers are moved.
 Then, in order to enable the-cleanliness of this wafer treatment area to
 obtain a high cleanliness of about class 1, the ULPA filters are disposed
 on the ceilings of the wafer treatment area, a wafer stocker area and an
 area for transporting wafers which are not protected with dust-proof
 cases. Then, the HEPA filter or the air-insulation panel are disposed on
 the ceiling of the area of the rear portion of each treatment equipment
 and the ceiling of other maintenance area, if necessary. If the treatment
 equipment is disposed within the clean room as described above, then the
 areas which are requested to become high in cleanliness may be collected
 efficiently so that the highly-efficient dust-collecting filters such as
 ULPA filters may be centralized in that area. As a result, it becomes
 possible to realize the useful layout of the dust-collecting filters, the
 supply amount of the air-conditioned air in the whole of the clean room
 can be suppressed to be small, and the air conditioner may be operated
 with a satisfactory operation efficiency. Further, if the treatment
 equipment 50 is partitioned by a partitioning member 52 such as an
 electrostatic shielding transparent acrylic plate, then the portions shown
 hatched in FIG. 7 become working rooms having a high cleanliness.
 In particular, most of the recent wafer treatment equipment have a function
 to maintain a high cleanliness. Accordingly, if such wafer treatment
 equipment is installed, then it is possible to suppress an area of the
 area which is requested to have a high cleanliness in the clean room to be
 smaller. The dust-collecting filter becomes much more expensive as its
 performance increases. Accordingly, if the filter of high efficiency is
 disposed on all of the ceilings in accordance with an area whose
 cleanliness is requested to be highest, then the cost thereof increases.
 On the other hand, if a filter of efficiency corresponding to a necessity
 is properly disposed in each portion, then it is possible to reduce the
 cost while maintaining a necessary cleanliness.
 As described above, if the whole of the ceiling is formed as the system
 ceiling and the highly-efficient ULPA filter is disposed only in the area
 which requires especially high cleanliness, then the cleanliness of the
 necessary portion may be raised more than ever while most of the existing
 facilities is used effectively and the ability of the air conditioner does
 not become insufficient. If the cleanliness of the area in which equipment
 for effecting a variety of treatments on wafers are disposed is set to be
 class 1 or higher, then in the case of DRAM (dynamic random-access
 memory), it becomes possible to manufacture integrated circuits of
 integration degree of 16 megabits or larger. Also, if the above-described
 system ceiling is used, then when the layout/arrangement of the line is
 varied, it becomes possible to realize the optimum filter layout pattern
 in accordance with a cleanliness required by a semiconductor fabrication
 line. Further, if the whole of the ceiling is formed as the system
 ceiling, then it becomes possible to partly remodel the existing clean
 room in which the air conditioner is installed on the assumption that the
 HEPA filter is disposed on the whole of the ceiling in accordance with the
 integration degree of semiconductors. Specifically, utilizing most of
 facilities such as existing air conditioners, it becomes possible to
 remodel the existing clean room into a semiconductor fabrication clean
 room in which a high cleanliness is requested while the cost thereof is
 suppressed.
 A method in which the area B (e.g. cleanliness class is 10000) whose
 cleanliness is lower than that of the area A is remodeled into a clean
 room having the same cleanliness as that of the area A as the area A is
 remodeled in FIGS. 1 and 2 will be described next. Since the area B is so
 far isolated from the area A by the wall 10, a construction for removing
 this wall 10 becomes necessary. Moreover, the area B has not been
 requested to have such a high cleanliness. Since this is the first time
 that the area B is requested to have a high cleanliness (e.g. about
 cleanliness class 1), new air conditioners and other facilities should be
 installed in the area B, and hence a construction therefor becomes
 necessary.
 To this end, initially, as shown in FIG. 4, a false partition panel 40 is
 installed on the side of the area A adjacent to the wall 10 of both of the
 first and second floors. As a means of this false partition panel, there
 may be used a partition panel of the same material as the wall material
 used in the conventional clean room, e.g. steel partition panel coated
 with a dust-proof paint in order to avoid the occurrence of static
 electricity and which can be detached with ease. The false partition panel
 40 is requested to have an airtight degree to the extent that dusts
 occurred when the wall 10 is demolished can be prevented from entering the
 area A and also requested that it can be detached with ease. A timing at
 which the false partition panel 40 is installed is such one that a
 cleanliness of about cleanliness class 1 is expected to be obtained after
 a period during which the working room is driven in order to increase a
 cleanliness since the working room on the area A side was expanded and the
 construction for increasing the cleanliness was ended. Therefore, until
 that period, the area B may be used as it is.
 After the false partition panel 40 is installed, the air conditioner for
 the area B is stopped, and the wall 10 that has completely partitioned the
 area A and the area B is demolished. Although dusts are generated during
 this construction for demolishing the wall 10, the false partition panel
 40 may protect the clean room on the area A side from the dusts.
 A true partition panel 41 is installed on the place where the demolished
 wall 10 was built. As the true partition panel 10, there may be used a
 partition panel of the same material as the false partition panel 40, e.g.
 steel partition panel coated with a dust-proof paint in order to avoid the
 occurrence of static electricity and which can be detached with ease.
 Concurrently with this work, the existing air conditioner of the area B is
 replaced with the same air conditioner of the area A, the ceiling of the
 area B is reformed into the system ceiling on which the dust-collecting
 filer of necessary efficiency is disposed in response to the area. Also,
 there is carried out a predetermined construction such as to form the
 floor of the area B as the free access floor. At the stage in which this
 construction is ended, the new air conditioner for the area B is driven in
 order to increase a cleanliness. In general, it takes about one month to
 achieve a necessary cleanliness since the driving for cleanliness is
 started. When a necessary cleanliness (e.g. about cleanliness class 1) is
 achieved in this manner, the true partition panel 41 which isolated the
 areas A and B may be removed. Incidentally, according to the necessity,
 more lines 20.sub.6, 20.sub.7 and stations 22.sub.6, 22.sub.7 may be built
 and the interbay transport machine 21 may be extended in accordance
 therewith.
 Incidentally, since this true partition panel 41 is made of the material
 for the clean room and may be easily removed, if this true partition panel
 41 need not be removed immediately, this true partition panel 41 may be
 removed later at any time according to the necessity. Under the condition
 that the true partition panel 41 remains as it is, the clean room may be
 used independently as the areas A and B as before. In this case, it is
 considered that the false partition panel 40 is left instead of the true
 partition panel 41. However, if so, the position of the partition panel is
 displaced from the position of the original wall 10 to the side of the
 area A with the result that the false partition panel 40 exists in
 somewhere of the air conditioner in the area A adjacent to the wall 10. In
 that case, if the cleanliness of the areas A and B is different, it is not
 desirable that the air conditioner adsorbs the air from the region in
 which the cleanliness is low. Accordingly, when the area A and the area B
 are independently used, the false partition panel 40 is removed finally
 and the true partition panel should preferably be left.
 The case in which the areas A and B are remodeled at substantially the same
 period has been described so far. This method may apply for the case in
 which a general room isolated from the adjacent existing room by a wall is
 remodeled into a new clean room and a wide clean room is obtained by
 removing the wall between it and the adjacent clean room as well. Also,
 while continuing the driving of the original clean room, the adjacent
 general room may be remodeled into a clean room. Also in this case, while
 a false partition panel is left between adjacent clean rooms, such clean
 rooms may be used as independent clean rooms, respectively.
 As described above, when the wall 10 between the areas A and B is
 demolished, the false partition panel is disposed near the wall 10. This
 method using the false partition panel is not limited to the case in which
 two areas are jointed by demolishing the wall but may be apply for the
 case in which a high cleanliness is realized by remodeling the area A as
 well. Specifically, when a remodeling construction for increasing the
 cleanliness of the area A is made, instead of stopping the operation of
 the whole of the area A so that the whole of the area A is constructed at
 the same time, the area A is divided into a plurality of small rooms by
 using the false partition panels, each small room is sequentially
 constructed in a necessary manner, a working for increasing a cleanliness
 is sequentially started from the small room whose construction is ended,
 and finally, a predetermined cleanliness is achieved with respect to the
 whole of the area A. If this method is used, then a period required to
 start the driving of the clean room may be reduced so that a period in
 which a predetermined cleanliness is achieved may be reduced. Then, an
 operation of line may be started from the small room with the
 predetermined cleanliness being achieved.
 In this case, a minimum division in which the false partition panel is
 installed is made corresponding to a minimum unit of air conditioner. In
 FIG. 1, for example, there are provided the three air conditioners
 14.sub.1, 14.sub.2, 14.sub.3 for the area A. Accordingly, in this case,
 the area A is divided into three small rooms similarly to the number of
 the air conditioners by using two false partition panels relative to the
 area A. Then, the remodeling construction and the work for increasing the
 cleanliness are started from the small room adjacent to the area B in FIG.
 1, and the operation of the line is started from the small room in which
 the predetermined cleanliness was achieved. When the cleanliness of the
 adjacent small rooms becomes the same, the false partition panel between
 such adjacent small rooms may be removed.
 As shown in FIG. 8, for example, let it be assumed that one existing clean
 room 60 is divided by a wall 61 into two (or more than two) areas 62, 63
 and that air conditioners 64, 65 are disposed in the areas 62, 63,
 respectively. Such example is the case that the clean room should be
 divided into working rooms such as when the area 62, for example, is used
 as a working room in which acid-based substance is used and the area 63 is
 used as a working room in which an alkaline-based substance is used.
 Dust-collecting filters 66, 67 are disposed on the ceilings of the
 respective areas 62, 63, and the floor of each of the areas 62, 63 is
 formed as the free access floor of the grated panel structure.
 Incidentally, pre-filters 70, 71 are disposed on the upper portions of the
 air conditioners 64, 65.
 When the cleanliness of the whole of the clean room 60 is increased, since
 the clean room 60 is divided by the wall 61 into the two regions 62, 63,
 during a period in which one area is being remodeled, the other area is
 continuously driven as it is. At the stage the remodeling construction of
 one area is ended and a predetermined cleanliness is achieved, the
 remodeling construction of the other area may be started. According to
 this method, the remodeling construction can be advanced efficiently so
 that during a period in which one area cannot be driven because of the
 remodeling construction, the other area can be driven. Thus, a decrease of
 a throughput of the whole of the factory may be held small. Also, although
 the whole of the areas cannot be actuated at the same time, it becomes
 possible to actuate only a part of the area.
 Incidentally, the present invention is not limited to the above-described
 embodiment, and may be variously modified without departing from the scope
 of the invention. For example, while the cleanliness is improved and the
 clean room is expanded up to the adjacent general room when there is a
 clean room as described above, the present invention is not limited
 thereto, and may apply for the case in which a general building, which is
 not the clean room, is remodeled into a clean room by the above similar
 construction as well.
 As set forth above, according to the present invention, it is possible to
 provide a clean room remodeling method in which when the existing clean
 room is remodeled into the clean room having a higher cleanliness, the
 existing air conditioner may be used as it is, a new air conditioner need
 not be installed by the remodeling construction, a clean room having a
 higher cleanliness may be obtained while the existing facilities are
 utilized effectively and in which the operation of the clean room can be
 started earlier. Further, it is possible to provide a clean room
 remodeling method in which an operation of a clean room can be started
 earlier when a single clean room is formed by removing a wall between two
 adjacent clean rooms and when a clean room is expanded up to the adjacent
 general room.
 Having described a preferred embodiment of the invention with reference to
 the accompanying drawings, it is to be understood that the invention is
 not limited to those precise embodiments and that various changes and
 modifications could be effected therein by one skilled in the art without
 departing from the spirit or scope of the invention as defined in the
 appended claims.