reference will now be made in detail to preferred embodiments of the present invention , examples of which are illustrated in the accompanying drawings . fig4 is a plan view showing a multi - chamber system of an etching facility for manufacturing semiconductor devices according to one preferred embodiment of the present invention . referring to fig4 , the multi - chamber system is constructed in such a manner that a cassette 41 having wafers stacked thereon is mounted on a cassette stage 42 , and eight processing chambers 45 for carrying out processes are displaced in parallel with multi - layers on both sides of a transfer path 100 , four of which are shown in the plan view of fig4 . the transfer path 100 has a shape having a narrow width , preferably a rectangular shape , and a transfer mechanism 52 is provided in the transfer path 100 in order to load and unload the wafers stacked on the cassette stage 42 into each of the eight processing chambers 45 . the cassette stage 42 includes a cassette elevator for moving the cassette up and down and can be moved horizontally so as to switch the locations of cassettes . the processing chambers 45 can be aligned in a single layer , but considering the efficiency of the space , a two - layer arrangement may be used as shown in fig5 , each layer having four processing chambers 45 aligned in parallel . with this arrangement , each layer comprises four processing chambers 45 , two load lock chambers 43 which are the same size as those in the conventional multi - chamber system 10 of fig1 , and one transfer path 100 . therefore , the facility width “ w ” of the multi - chamber system 40 of the present invention is the sum of the widths of those of the two processing chambers 45 and the one transfer path 100 . this width “ w ” is minimized , because the width of the hexagonal pillar - shaped central chamber in the conventional system is replaced by that of the transfer path 100 in the multi - chamber system , and the transfer path 100 is only a little wider than the diameter of one wafer . in addition , the depth of the multi - chamber system is minimized , because the depth of the hexagonal pillar - shaped central chamber , each side of which is slightly larger than the diameter of a wafer , is replaced by that of the load lock chamber 43 . the shape of the load lock chamber 43 can be optimized as a regular rectangular pillar shape so as to be only slightly deeper than the diameter of one wafer , thereby decreasing the width and depth of the whole facility . therefore , the area occupied by a single - layer structure ( not shown ) of the multi - chamber system according to the present invention is less than the area occupied by the conventional system ; and the multi - layer structure as shown in fig4 and 5 is even more compact . furthermore , the multi - layer structure preferably has 2 to 5 layers . in addition , the space occupied by the load lock chamber 43 can be minimized , and the volume of the vacuum facility or supplementary apparatus can be reduced , thereby minimizing expenses for the facility and its installation . in addition , as described below , the transfer mechanism 52 allows wafers to be moved quickly by holding them using vacuum pressure so that it is not necessary to install a supplementary vacuum pressure generator . a vacuum is not formed in the transfer path 100 , unlike the case of the conventional central chamber , thereby allowing use of the multi - layer structure for the processing chambers . since a vacuum is not formed in the transfer path 100 , the wafers may be vacuum absorbed to the transfer arm thus providing faster wafer transfers , in contrast to the conventional case , wherein the wafers inside the central chamber were merely gravity - supported by the transfer arm , and the wafers had to be moved slowly so as not to fall off the transfer arm . for those processing chambers requiring a relatively low vacuum state , such as a base oven process , an ashing process , a pre / post etching process , etc ., a gate ( not shown ) is formed toward the transfer path 100 and is selectively opened and closed so as to allow for the passage of wafers . a vacuum pressure generator 45 ′ is installed inside the processing chamber 45 in order to form a vacuum pressure therein , with the processing chamber 45 carrying out the dry - etching process requiring a high - vacuum to form a plasma . therefore , in order to minimize the time or the energy waste necessary to form a high - vacuum state in the processing chamber after being directly exposed to the atmospheric pressure environment , a load lock chamber 43 having a low - vacuum state is connected to one side of the processing chamber 45 and serves as a stand - by region for wafers , and a gate 46 , 49 is formed on one side of the load lock chamber 43 facing the transfer path 100 . each load lock chamber 43 comprises : a transfer arm 54 ( fig6 ) for receiving wafers from the transfer mechanism 52 and transferring them to the processing chamber ; an inner transfer device 44 for moving the transfer arm 54 ; a gate 46 , 49 formed on one side of the transfer path 100 which is selectively opened and closed to allow the passage of wafers ; and another gate 47 , 48 , 50 , 51 provided on one side of the processing chamber 45 that is selectively opened and closed to allow the passage of wafers between the processing chamber 45 and the load lock chamber 43 . here , the transfer arm 54 of the load lock chamber 43 , and the inner transfer device 44 inside the chamber can be provided in each of the two load lock chambers 43 so as to individually transfer two wafers into the two processing chambers 45 simultaneously . a vacuum pressure generator 43 ′ may be provided in the load lock chamber 43 so as to form a low - vacuum therein in order to prevent an abrupt vacuum pressure differential inside the processing chamber 45 when the wafers are transferred through the gate 47 , 48 , 50 , 51 between the high vacuum processing chamber 45 and the load lock chamber 43 . such a vacuum pressure generator 43 ′ using a vacuum pump is well - known to those skilled in the art . in addition , as shown in fig4 and fig5 , two processing chambers 45 are placed on both sides , i . e ., before and after the load lock chamber 43 , respectively , so as to have one load lock chamber 43 in common . in other embodiments , three or more processing chambers 45 may be oriented so as to share one common load lock chamber . since the processing chambers 45 are connected to one another through the gates , wafers passing through one specific process are directly moved to another processing chamber , thereby allowing the transfer of wafers between processing chambers . as shown in fig5 and 6 , the transfer mechanism 52 of the present invention installed on the transfer path 100 comprises : a transfer arm 53 for selectively holding the wafers ; a transfer robot 52 a for loading and unloading wafers to the processing chamber by moving the transfer arm 53 ; a horizontal driving part 52 b for horizontally moving the transfer robot ; a vertical driving part 52 c for moving the transfer robot up and down ; and a controller 52 d for applying a control signal to the transfer robot 52 a , the horizontal driving part 52 b , and the vertical driving part 52 c . the transfer arm 53 further includes a vacuum line 52 e in order to selectively vacuum - absorb wafers 1 placed thereon . the horizontal and vertical movement is indicated by the arrows in fig5 and 6 . the transfer arm 53 , as shown in fig5 , can be constructed such that one wafer is transferred at a time , but can also be constructed as a 4 - arm system , wherein four arms are connectably provided in two layers so as to individually transport four wafers at the same time to the load lock chambers . such a 4 - arm system for transferring four wafers individually at a time , or 2 - arm system , 3 - arm system , etc ., which are employed so as to move 2 or 3 wafers at a time , are well - known to those skilled in the art . also well - known to those skilled in the art are : the horizontal driving part 52 b , which horizontally moves along a rail or guide rod by using a motor or an air cylinder as a driving source , the vertical driving part 52 c , which moves up and down along a rail or guide rod ; the transfer arm 53 and the transfer robot 52 a . various modifications or alterations of these mechanisms are contemplated within the scope of the present invention . the multi - chamber system for manufacturing semiconductor devices as shown in fig6 is constructed in such a manner that a cassette 41 having a plurality of wafers 1 stacked therein is mounted on the cassette stage 42 , and the horizontal driving part 52 b and the vertical driving part 52 c of the transfer mechanism 52 are driven on receipt of the control signal from a controller 52 d so as to control the movement of the transfer robot 52 a toward the wafers 1 inside the cassette 41 . in operation , the transfer mechanism 52 accesses the wafer 1 , the transfer robot 52 a receives the control signal from the controller 52 d , and then makes the transfer arm 53 contact the wafers 1 . the transfer arm 53 having the vacuum line 52 e vacuum - absorbs the wafers 1 to one side of the transfer arm 53 . when the wafer 1 fixed on the transfer arm 53 is to be moved to a specific processing chamber 45 disposed in the first chamber layer , the wafer 1 is first moved to the load lock chamber 43 connected to the specific chamber 45 in the first chamber layer by the horizontal driving part 52 b under control from the controller 52 d . at this time , the gate 46 of the load lock chamber 43 facing the transfer path 100 is opened , and the transfer arm 53 of the transfer mechanism 52 is inserted . then the vacuum pressure of the vacuum line 52 e is shut off , and the wafer 1 is mounted on the transfer arm 54 inside the load lock chamber 43 . the transfer arm 53 of the transfer mechanism 52 exits the load lock chamber 43 , and the gate 46 is then closed . then , the vacuum pressure generator 43 ′ of the load lock chamber 43 is operated so as to place the inside of the load lock chamber 43 into a low vacuum state . after the load lock chamber 43 reaches a certain low vacuum level , the gate ( e . g ., gate 47 ) of the load lock chamber 43 facing the processing chamber 45 is opened , and the inner transfer device 44 of the load lock chamber 43 transfers the wafers mounted on the transfer arm 54 into the processing chamber 45 . while vacuum absorption of the wafer at this stage is difficult because of the low vacuum pressure state in the load lock chamber 43 , the small space within the load lock chamber 43 is not as wide as in the conventional one , so that it takes just a short time for the transfer arm 54 to mount the wafers in the processing chamber 45 , even at the low speed . then the transfer arm 54 exits the processing chamber 45 , the gate 47 is closed , and the vacuum pressure generator 45 ′ in the processing chamber 45 is operated , thereby forming a high vacuum inside the processing chamber 45 , after which the etching process is carried out . meanwhile , if the wafers 1 are to be moved to a specific processing chamber 45 on the second chamber layer , the controller 52 d controls both the horizontal driving part 52 b and the vertical driving part 52 c so as to transfer the wafers 1 to the load lock chamber 43 connected to the specific processing chamber 45 on the second chamber layer . the wafers 1 are moved up while vacuum absorbed by the transfer arm 53 of the transfer robot 52 a , and are inserted into the load lock chamber 43 . the subsequent steps are the same as described above for a processing chamber on the first layer . when the wafers have been transferred and loaded into a plurality of processing chambers 45 , corresponding processes are carried out in the respective processing chambers , and the wafers are unloaded in order of process completion . then , the wafers are transferred to the cassette stage 42 or transferred to a specific processing chamber on a specific layer upon receipt of a control signal from the controller 52 d . when a 4 - arm system is installed on the transfer mechanism 52 , the transfer mechanism 52 picks up four wafers from the cassette and places two wafers into each of two load lock chambers 43 connected to specific processing chambers . when the inner transfer device 44 and the transfer arm 54 are constructed with a 2 - arm system , two wafers are picked up and transferred , one each into two processing chambers . after processing , two or one wafer is transferred from the processing chamber to the transfer mechanism 52 so as to carry out a post - process step . in another aspect of the present invention as shown in fig7 , a multi - chamber system of an etching facility for manufacturing semiconductor devices comprises : a first cassette stage 60 for mounting a cassette containing unprocessed wafers ; a second cassette stage 70 for mounting a cassette containing processed wafers ; a plurality of processing chambers 45 aligned on both sides of a rectangular - shaped transfer path 100 , the processing chambers being arranged in parallel in a multi - layered path for wafers , and for carrying out processing of wafers ; and a transfer mechanism 52 installed in the path allowing for vertical / horizontal reciprocal movement , and including a transfer robot for transferring wafers mounted on the first cassette stage 60 to the plurality of processing chambers 45 , and for transferring wafers into the second cassette stage 70 after processing . this embodiment is constructed such that the wafers passing through all of the processing detailed above in the description of the first embodiment are stacked on the second cassette stage 70 , and such that the multi - chamber system is easily connected to other processing facilities 20 as shown in fig8 . referring to fig8 , wafers are supplied into the multi - chamber system through the first cassette stage 60 installed in the front of the facility , and pass through a plurality of processes in the plurality of processing chambers 45 , and are stacked on the second cassette stage 70 on the back side of the facility . then , wafers are moved to another facility 20 by an automatic transfer part of the other facility 20 , pass through processing therein , are transferred into the side of a second facility 20 ′, pass through that facility 20 ′, and are stacked on the cassette stage of the second facility 20 ′ on the right side of the multi - chamber system . therefore , unlike the conventional case , wherein all cassette stages are provided on the front sides of the facility , therefore requiring a supplementary cassette transfer car in order to transport the cassette between facilities , the necessity for a supplementary cassette transfer means for transporting cassettes between facilities is reduced according to the present invention . in addition , as shown in fig9 , the number of processing chambers 45 can be increased , and the transfer path 100 extended , so that more processing chambers 45 and load lock chambers 43 are aligned on both sides of the transfer path 100 . when the length of the transfer path 100 is extended , a first transfer mechanism 62 and a second transfer mechanism 72 can be installed , wherein the transfer from one to the other is possible . therefore , unlike the conventional multi - chamber system , the number of processing chambers can be increased without changing the width of the facility . however , there are limitations in the length of the facility and the facility control , etc . according to a third embodiment of the present invention , as shown in fig1 , a multi - chamber system of an etching facility for manufacturing semiconductor devices comprises : a cassette stage 42 for mounting a cassette having wafers stacked thereon ; a plurality of processing chambers 45 aligned along one side of a transfer path 100 , the processing chambers being arranged in multi - layers for carrying out wafer processing ; and a transfer mechanism 52 provided in the transfer path 100 for loading and unloading wafers into the plurality of processing chambers using vertical and horizontal movement . the processing chambers 45 and the load lock chambers 43 , which are stand - by areas for wafers , are aligned on only one side of the transfer path 100 . as above , each load lock chamber 43 comprises : a transfer arm for transferring wafers from the transfer mechanism 52 to the processing chamber ; an inner transfer device for transferring the transfer arm ; a gate confronting the transfer path and another gate confronting the processing chamber , which are selectively opened and closed to allow passage of the wafers . the transfer mechanism 52 of the third embodiment of the present invention , unlike the first and the second embodiments of the present invention , loads the wafers on the first cassette stage 60 in only one direction after horizontally - rotating 90 degrees while vacuum - absorbing the wafers , because the processing chambers 45 and the load lock chambers 43 are aligned along only one side . the transfer mechanism 52 transports unprocessed wafers stacked on the cassette mounted on the first cassette stage 60 to the processing chamber 45 , and after processing , transports the wafers from the processing chamber to the second cassette stage 70 , which is located for easy transfer to subsequent processes . that is , as shown in fig1 , the second cassette stage 70 is displaced on the opposite side of the transfer path from the processing chambers 45 and the load lock chambers 43 , so that the wafers after one process are easily transported to subsequent processes . therefore , according to the third embodiment of the present invention , the efficiency of space usage is increased by applying the multi - chamber system of the present invention to the rest of the space in the cleanroom after installing various facilities with various shapes and volumes . accordingly , in the multi - chamber system of an etching facility for manufacturing semiconductor devices , a plurality of processing chambers are aligned in parallel and with multi - layers , thereby greatly reducing the space , width and volume of the facility . further , the expenses for the facilities and installation can be minimized by reducing the space requiring a vacuum state , and the connection with other processing facilities is easy , such that the efficiency of space usage is improved thereby increasing the transportation speed of wafers . in the accompanying drawings and specification , there have been disclosed typical preferred embodiments of the invention and , although specific terms are employed , they are used in a generic and descriptive sense only and not for purposes of limitation , the scope of the invention being set forth in the following claims . it will be apparent to those skilled in the art that various modifications and variations of the present invention can be made without departing from the spirit or scope of the invention . thus , it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents .