fig3 is a perspective view of a first embodiment of the present invention , for storing 6 inches silicon wafers , illustrating the structural configuration thereof . fig4 is a top view of the embodiment , fig5 is a front view of the same , and fig6 is a cross - sectional side view taken along line a -- a shown in fig4 . the wafer carrier 16 comprises a storing chamber 7 and an air cleaning means 8 . the storing chamber 7 has a structural configuration similar to that of the prior art wafer carrier 6 shown in fig1 . side plates 1a and 1b stand facing to each other , forming a storing space therebetween for storing the wafers 5 . horizontal grooves 2a and 2b are formed on the inner surfaces of the side plates 1a and 1b in the same manner as those of fig1 . thereby , the cross - section of the grooves 2a and 2b is v - shaped which serves to minimize contacting area between the groove surfaces and the edges of the wafers 5 inserted therein , in a short line contact . the depth of the grooves 2a and 2b is selected such that both grooves 2a and 2b are adaptable to receive the sides of the wafers 5 . thus , the wafers 5 are held in parallel and horizontally between the side plates 1a and 1b , namely in the storing space , keeping the spacing distance therebetween . the storing space is surrounded by a top plate 3 , side plates 1a and 1b , and a bottom plate 4 . generally , the bottom plate 4 has a narrower width than that of the side plates 2a and 2b for the convenience for loading and unloading of the wafers 5 . with this configuration , the storing chamber 7 has openings at the front side , and the rear side . the front opening serves to load and unload the wafers 5 , and an outlet of a clean air stream . the rear opening serves to introduce clean air stream which is sent by the air cleaning means 8 . the material of the storing chamber 7 is selected from silica , polypropylene , pfa ( copolymer of tetrafluoroethylene perfluoro alkyl vinyl ether ) and the like . as illustrated in the figures , the air cleaning means 8 includes a motor fan 10 , a vertical air duct 11 , air filter 12 , an electrical power source , usually a secondary battery 13 , and a housing 15 forming the vertical air duct 11 . air is taken in by the motor fan 10 onto the duct 11 through an air inlet opening 9 which is opened in a part of the top plate of the housing 15 . the air cleaning means 8 has an air outlet opening for sending an air stream out , which is formed on a vertical side of the duct 11 and has the same shape as that of the air inlet opening of the storing chamber 7 . both openings are coupled to each other permanently or demountable by a coupling means ( not shown in fig3 and 5 , but shown in fig7 which will be referred later ). a dc motor fan 10 ( rating voltage dc 12v , power consumption 1 . 8 w , maximum spending air capacity 0 . 45 m 3 / min , static pressure 13 mmaq ) is disposed at the upper side of the vertical duct 11 , and two nickel - cadmium ( nicd ) secondary batteries 13 ( output voltage dc 12v , capacity 0 . 5 ah ) are disposed at both sides of the motor fan 10 . the secndary batteries 13 are charged occasionally by an external battery charger ( not shown ) through a charging socket terminal 14 disposed on the surface of the housing 15 as shown in fig3 . for a practical use , another socket , a driving socket terminal 17 , is also disposed besides the charging socket terminal 14 , for driving the motor fan 10 by the application of an external power source ( not shown ) for saving the discharge of the secondary battery 13 . the relevant circuitry ( not shown ) is formed on th einner side of the housing 15 , operatively connecting the motor fan 10 , secondary batteries 13 , and socket terminals 14 and 17 , description of which is omitted . a 0 . 1 μm hepa ( high efficiency particulate air ) filter 12 , a product of nitta co ., is disposed across the air outlet opening to filter the air sent through the vertical duct 11 . the collection efficiency for the particles of 0 . 1 μm size is above 99 , 999 %, and the filter pressure drop at the air flow rate of 0 . 2 m 3 / sec . is below 20 mm aq . with the above - described structural configuration of the wafer carrier 16 , air flow generated by the motor fan 10 flows into the vertical duct 11 , filtered by the hepa filter 12 , and is sent into the storing chamber 7 wherein the wafers 5 are placed horizontally and spaced from each other . because the flow resistance of the vertical duct 11 is fairly lower than that of the filter 12 , and the side of the storing chamber 7 is enclosed by the side plates 1a , 1b , and top plate 3 , and is partially closed by the bottom plate 4 , the filtered clean air is distributed almost uniformly along the filter surface , and flows along the surfaces of the wafers 5 as indicated by arrows in fig6 with a fairy high speed such as 0 . 1 m / sec to 0 . 2 m / sec . major part of the air flows between the wafers 5 forming laminated air stream without any turbulence , stagnation , and eddy . the positioning of the side plates 1a and 1b in the extreme vicinity of the ends of the wafers 5 , also serves to form the laminated , high speed clean air stream . the motor fan 10 can be kept driven during the whole time when the wafers 5 are stored inside the wafer carrier 16 . as a result , the wafers 5 are completely protected from any particulate contamination , even though personnel exist in the vicinity of the wafers 5 . in addition , the particulate contamination originally adhered to the surfaces of the wafers 5 are also effectively removed by holding the wafers 5 in the wafer carrier 16 for a period . the effectiveness of the wafer carrier 16 according to the present invention , which is shown in fig3 is measured . in an environment of over class 1 , 000 , 000 of federal standard no . 209b , the wafer carrier 16 is placed and the motor fan 10 was operated . at the starting moment of the measurement , of course , the storing chamber 7 of the wafer carrier 16 is filled with the air of the environment . ( a ) after 30 seconds operation , the resulted cleanness inside the storing chamber 7 of the wafer carrier 16 was measured . at the center portion , the cleanness was below 3 ( 0 . 1μ class ), and at the peripheral portion spaced from the side plate 1a and 1b by 10 mm , below 10 . this means that the number of particles larger than 0 . 1 μm contained in the storing chamber 7 is below 1 . ( the volume of the storing chamber 7 is approximately 0 . 1 cubic feet ). ( b ) 25 pieces of 6 inches silicon wafers 5 were stored in a wafer carrier 16 according to the present invention and the same number of the wafers 5 in a prior art wafer carrier 6 , at the same time , for 72 hours , in a clean room of class 1000 where operators were working . the number of the particles with sizes larger than 0 . 2 μm , attached to the surfaces of the wafers , were measured . the original numbers of the particles attached to the surfaces of the wafers 5 ranged from 0 to 30 . the increase in the number of the particles after 72 hours , was 16 per wafer in average for the new wafer carrier 16 , and 1600 for the prior art wafer carrier 6 . fig7 ( a ) and fig7 ( b ) are partial cross - sectional views of the coupling means for coupling the wafer storing chamber 7 and the air cleaning means 8 . these coupling mechanisms are popular ones . fig7 ( a ) illustrates partially the structure of a permanent coupling , comprising a flange 21 disposed around the edge portion of a housing comprising top plate 3 , side plates 1a , 1b , and bottom plate 4 . the flange 21 is coupled to the air outlet opening of the air cleaning means 8 , by screwing the flange 21 to the housing 15 with screws 23 . an 0 ring 22 is inserted at the coupling contact to increase the air - tightness of the coupling . in stead of the use of the above - described structure , a direct welding method is applicable for the permanent coupling . fig7 ( b ) is a cross - sectional view , illustrating a partial structure of a demountable coupling . a coupling sleeve 26 is disposed on the outer surface of the housing 15 of the air cleaning means 8 , along the edge of the air outlet opening . the inner side surface of the coupling sleeve 26 is formed so as to fit with the outer side surface of the above described housing surrounding the storing space of the storing chamber 7 . demountable coupling between the sleeve 26 and the housing is achieved by inserting the protrusions 24 formed on the outer side surface of the housing into the corresponding pits 25 formed on the inner side surfce of the sleeve 26 , utilizing the elastic deformation of the relevant parts . with such demountable structure , the storing chamber 7 is separated from the air cleaning means , and can be utilized as a wafer cassette for wet etching process and the like . fig8 is a perspective view of a second embodiment having a modified structure of that of the first embodiment shown in fig3 . fig9 is a top view of the second embdiment of fig8 fig1 is a front of view of the same , and fig1 is a cross - sectional side view taken along line b -- b designated in fig9 . the modified points are apparent by referring to the drawings . the second embodiment has an air filter 12 disposed horizontarlly . the top plate 3 of the storing chamber 7 is eleminated . the filtered clean air flows in a downward direction . other structural configuration is similar to that of the first embodiment , so further description thereof is omitted . major part of the filtered air flow is guided into a vertical duct 11 and distributed into a storing space of wafers 5 , running along the surfaces of the wafers 5 as indicated by arrows . the air flow distributed between the wafers 5 forms laminated clean air streams . there is an advantage that the structure of the second embodiment has less occupying area than the first embodiment . the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof . the presently disclosed embodiments are , therefore , to be considered in all respects as illustrative and not restrictive , the scope of the invention being indicated by the appended claims , rather than the foregoing description , and all changes which come within the meaning and range of equivalency of the claims are , therefore , to be embraced therein .