Abstract:
An enclosure  23 A that defines a drying chamber  23  is configured of a pair of enclosing elements  23   c  and  23   d  and a base element  23   b.  When wafers enter or leave the drying chamber  23,  the enclosing elements  23   c  and  23   d  are lifted upward by vertical air cylinders  42  to separate them from the base element  23   b.  The enclosing elements  23   c  and  23   d  are then moved in directions that mutually separate them. To dry wafers within the drying chamber  23,  the enclosing elements and the base element  23   b  are mutually engaged to form a hermetic seal, in the opposite sequence. 
     The present invention reduces the dimensions of the drying chamber without impeding the work of moving wafers into and out of the drying chamber. This makes it possible to reduce the internal volume of the drying chamber, achieving a reduction is the consumption of drying gas, an improvement in the drying efficiency, and a reduction in overall size of the apparatus.

Description:
This application is a divisional of Ser. No. 09/116,531, filed Jul. 16, 1998, now U.S. Pat. No. 6,158,449. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of and apparatus for cleaning objects to be treated, such as semiconductor wafers or LCD (liquid crystal display) substrates etc., by immersing them in a cleaning liquid such as a chemical or a rinse, and sequentially drying the objects cleaned. 
     2. Description of the Related Art 
     During the process of fabricating a semiconductor device, a cleaning method is widely used to sequentially immerse objects to be treated or processed, such as semiconductor wafers or glass LCD substrates, into a processing tank filled with a processing liquid such as a chemical or rinse (cleaning liquid), to wash them. 
     A cleaning and drying apparatus of this type is provided with a drying device wherein a drying gas obtained from vapor of a volatile organic solvent such as isopropyl alcohol (IPA) is brought into contact with the surfaces of the wafers after the cleaning, the vapor of the drying gas condenses thereon or adheres thereto, and thus moisture on the wafers is removed, drying the wafers. 
     A conventional cleaning and drying apparatus that is known in the art as a typical example of this type of cleaning and drying apparatus is shown in FIG.  27 . It comprises a cleaning tank A (cleaning chamber) which is filled with a chemical such as hydrofluoric acid and a rinse (cleaning liquid) such as distilled water, wherein objects to be treated, such as semiconductor wafers, are immersed in the chemical and cleaning liquid therein; a drying portion B positioned above the cleaning tank A; and a movement means such as a wafer boat C that holds a plurality of wafers W, such as 59 wafers W, and moves those wafers W into the cleaning tank a and the drying portion B. 
     Within the cleaning and drying apparatus of the above configuration, supply nozzles D that are connected selectively to a chemical source and a cleaning liquid source (not shown in the figure) are disposed within the cleaning tank A; drying gas supply nozzles E that are connected to a source (not shown in the figure) of a gas mixture of a drying gas such as IPA and nitrogen (N 2 ) are disposed within the drying portion B; an aperture G that is freely enterable by a wafer conveyor chuck E is provided in an upper portion of the drying portion B; and a lid H is provided for opening and closing the aperture G. 
     In the thus-configured cleaning and drying apparatus, a plurality of wafers W, such as 50 wafers W, that have been transferred into the drying portion B by the wafer conveyor chuck E are received by the wafer boat C which is on standby within the drying portion B, the wafer boat C that has received these wafers W is lowered into the cleaning tank A to move the wafers W thereinto, and chemical processing is performed by supplying a chemical thereto and cleaning is performed by supplying a cleaning liquid thereto until it overflows. After the chemical processing and cleaning have been completed, the wafer boat C rises to move the wafers W into the drying portion B, and a drying gas (IPA+N 2 ) is supplied from the drying gas supply nozzles E to bring the drying gas into contact with the wafers W, thus drying them. The dried wafers W are taken by the wafer conveyor chuck E that enters into the drying portion B and are conveyed outside, whereby one cycle of cleaning and drying is performed. 
     However, when the wafers W are transferred between the wafer boat C and the wafer conveyor chuck E that enters the drying portion B in the conventional cleaning and drying apparatus of this type, it is necessary to move the chuck portions sideways in order to enable the wafer conveyor chuck E to switch from a wafer holding state to a wafer non-holding state. It is therefore necessary to provide movement space within the drying portion B for the wafer conveyor chuck E, and the volume of the drying portion B must be increased accordingly. This increase in volume of the drying portion B not only leads to an increase in size of the apparatus, it raises further problems such as an increase in the amount of drying gas consumed therein and a lowering of the drying efficiency. 
     In addition, after the wafer boat C has risen to move the wafers W into the drying portion B of the above cleaning and drying apparatus, and during the drying process of supplying the drying gas to cause the drying gas to come into contact with the wafers W, the portions of the wafers W in contact with the wafer boat C that have been raised from within the cleaning liquid are in a state wherein drainage therefrom is bad and it is also difficult for the drying gas to come into contact therewith. Therefore, considerable time is required to dry the portions of the wafers W in contact with the wafer boat C, which causes a further increase in the consumption of drying gas, and this raises problems concerning decreased drying efficiency and increased cost. There are further problems concerning the danger of unevenness in the drying and reductions in yield. 
     SUMMARY OF THE INVENTION 
     A first objective of the present invention is to provide a cleaning and drying apparatus which can be designed to have a drying chamber with a small volume so that the entire apparatus is more compact, wherein a reduction in the consumption of drying gas and an increase in the drying efficiency can be expected. 
     A second objective of the present invention is to provide a cleaning and drying apparatus and method which can be expected to solve the problem of bad drainage at held portions, provide good contact between those portions and the drying gas, shorten the drying time and reduce the consumption of drying gas, improve the drying efficiency and the yield, and also reduce costs. 
     In order to achieve the first objective, a first aspect of the present invention relates to a cleaning and drying apparatus having a cleaning chamber for cleaning an object and a drying chamber positioned above the cleaning chamber for drying the object, the apparatus including: an enclosure defining the drying chamber, the enclosure including first and second enclosing elements capable of relative movement, such that the enclosing elements are capable of adopting an engaged state and a separated state concomitant with the relative movement, wherein when the enclosing elements are in the separated state the first and second enclosing elements are spaced apart horizontally and the object is allowed to be transferred into and out of the drying chamber between the enclosing elements. 
     In order to achieve the second objective, a second aspect of the present invention relates to a cleaning and drying apparatus having a cleaning chamber for cleaning an object and a drying chamber positioned above the cleaning chamber for drying the object, the apparatus including: carrying means for carrying the object movable between the cleaning chamber and the drying chamber, the carrying means being in contact with a first portion of the object when the carrying means carries the object; and holding means provided in the drying chamber for holding the object in a second portion thereof, the second portion being different from the first portion. 
     In order to achieve the second objective, a third aspect of the present invention relates to a method of cleaning and drying an object, including the steps of: (a) accommodating the object in a cleaning chamber in a state in which a first portion of the object is in contact with carrying means, and cleaning the object by a cleaning liquid supplied into the cleaning chamber; (b) raising the carrying to move the object into a drying chamber provided above the cleaning chamber; (c) holding a second portion of the object that differs from the first portion by holding means, and making the carrying means be away from the object; and (d) drying the object with a drying gas, in a state in which the second portion of the object is held by the holding means. 
     The advantages and features of the present invention will be discussed in detail below, with reference to the accompanying figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic plan view of a cleaning and drying system to which the cleaning and drying apparatus of the present invention is applied; 
     FIG. 2 is a schematic side view of the cleaning and drying system of FIG. 1; 
     FIG. 3 is a cross-sectional view of a first embodiment of the cleaning and drying apparatus of the present invention; 
     FIG. 4 is a schematic lateral cross-sectional view of the cleaning and drying apparatus of FIG. 3; 
     FIG. 5 is a schematic perspective view of the cleaning and drying apparatus of FIG. 3; 
     FIG. 6 is a schematic cross-sectional view of an initial state of the enclosing elements of FIG. 3; 
     FIG. 7 is a schematic cross-sectional view of the raising of the enclosing elements of FIG. 3; 
     FIG. 8 is a schematic cross-sectional view of the relative separation of the enclosing elements of FIG. 3; 
     FIG. 9 is a schematic cross-sectional view of the operation of transferring wafers; 
     FIG. 10 is a schematic cross-sectional view of the operation of engaging the enclosing elements after the wafers have been transferred; 
     FIG. 11 is a schematic cross-sectional view of a wafer cleaning step; 
     FIG. 12 is a schematic cross-sectional view of a wafer drying step; 
     FIG. 13 is a schematic cross-sectional view of a step of removing the wafers after the drying; 
     FIGS. 14A and 14B are schematic views of another drive mechanism for the enclosing elements; 
     FIG. 15 is a cross-sectional view through a second embodiment of the cleaning and drying apparatus of the present invention; 
     FIG. 16 is a lateral cross-sectional view of the cleaning and drying apparatus of FIG. 15; 
     FIG. 17 is a perspective view illustrating the configuration of the second holder device of FIG. 15; 
     FIG. 18 is a schematic cross-sectional view illustrating the cleaning step in the first cleaning and drying method used in the cleaning and drying apparatus of FIG. 15; 
     FIG. 19 is a schematic cross-sectional view illustrating the step of moving wafers in the first cleaning and drying method; 
     FIG. 20 is a schematic cross-sectional view illustrating the step of transferring wafers from the first holder device to the second holder device in the first cleaning and drying method; 
     FIG. 21 is a schematic cross-sectional view illustrating a drying step in the first cleaning and drying method; 
     FIG. 22 is a schematic cross-sectional view illustrating the cleaning step in the second cleaning and drying method used in the cleaning and drying apparatus of FIG. 15; 
     FIG. 23 is a schematic cross-sectional view illustrating the step of moving wafers in second first cleaning and drying method; 
     FIG. 24 is a schematic cross-sectional view illustrating the step of transferring wafers from the first holder device to the second holder device in the second cleaning and drying method; 
     FIG. 25 is a schematic cross-sectional view illustrating a first drying step in the second cleaning and drying method; 
     FIG. 26 is a schematic cross-sectional view illustrating the step of transferring wafers from the first holder device to the second holder device in the second cleaning and drying method, and the second drying step therein; and 
     FIG. 27 is a schematic cross-sectional view of a conventional cleaning and drying apparatus. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Embodiments of the present invention are described below with reference to the accompanying figures. Note that this description relates to the application of the cleaning and drying apparatus of the present invention to a system for cleaning semiconductor wafers. 
     The description first concerns the overall configuration of a cleaning and drying system to which the cleaning and drying apparatus of the present invention is applied, with reference to FIGS. 1 and 2. FIG. 1 is a schematic plan view of an example of such a cleaning and drying system and FIG. 2 is a schematic side view thereof. 
     This cleaning and drying system is provided with a conveyor portion  2  for conveying carriers  1  into and out of the system, where each carrier  1  contains substrates to be processed which are semiconductor wafers W in a horizontal state; a processing portion  3  for processing the wafers W with chemicals or cleaning fluids and also drying them; and an interface portion  4  located between the conveyor portion  2  and the processing portion  3 , for receiving the wafers W, adjusting the positions thereof, and changing the attitudes thereof. 
     The conveyor portion  2  is provided with an inlet portion  5  and an outlet portion  6  aligned along one side edge portion of the cleaning and drying system. A sliding mounting table  7  is provided in each of an inlet port  5   a  of the inlet portion  5  and an outlet port  6   a  of the outlet portion  6 , to enable the carriers  1  to be moved freely into the inlet portion  5  and out of the outlet portion  6   
     Each of the inlet portion  5  and the outlet portion  6  is further provided with a carrier lifter  8 . Each carrier lifter  8  is capable of transferring a carrier  1  to and from the corresponding inlet portion or outlet portion, and is also capable of transferring a carrier  1  containing wafers W into a carrier standby portion  9  provided in an upper portion of the conveyor portion  2 , or transferring an empty carrier  1  that is in the carrier standby portion  9  (see FIG.  2 ). 
     The interface portion  4  is divided by a partitioning wall  4   c  into a first chamber  4   a  in close proximity to the inlet portion  5  and a second chamber  4   b  in close proximity to the outlet portion  6 . A wafer removal arm  10  that is capable of horizontal movement (in the X and Y directions), vertical movement (in the Z direction), and rotation (about the θ axis), for removing a plurality of wafers W from a carrier  1  in the inlet portion  5 ; a notch aligner  11  for detecting notches provided in the wafers W and causing them to be aligned; a spacing adjustment mechanism  12  for adjusting the spacing of a plurality of the wafers W that have been taken by the wafer removal arm  10 ; and a first attitude modification device  13  for changing the horizontal state of the wafers W to a vertical state are disposed within the first chamber  4   a.    
     A wafer transfer arm  14  for picking up a plurality of processed wafers W from the processing portion  3  while still in a vertical state and conveying them; a second attitude modification device  13 A for changing the vertical state of the wafers W received from the wafer transfer arm  14  to a horizontal state; and a wafer accommodation arm  15  that is capable of horizontal movement (in the X and Y directions), vertical movement (in the Z direction), and rotation (about the θ axis), for taking the plurality of wafers which have been converted to a horizontal state by the second attitude modification device  13 A and accommodating those wafers W in an empty carrier  1  that has been conveyed into the outlet portion  6  are disposed within the second chamber  4   b.    
     Note that the second chamber  4   b  is sealed from the exterior and the atmosphere therein can be replaced by an inert gas such as nitrogen (N 2 ) supplied from a nitrogen source (not shown in the figures). 
     A first processing unit  16  that removes particles and organic contaminants adhering to the wafers W; a second processing unit  17  that removes metallic contaminants adhering to the wafers W; a cleaning and drying apparatus  18  (or  18 ′) that removes oxides from the wafers W and is also provided with a drying device for drying the wafers W; and a chuck cleaning unit  19  are disposed in a line within the processing portion  3 . A wafer conveyor chuck  21  that is capable of horizontal movement (in the X and Y directions), vertical movement (in the Z direction), and rotation (about the θ axis) is disposed in a position corresponding to all of these units  16  to  19 . 
     First Preferred Embodiment of Cleaning and drying Apparatus 
     The description now turns to a first embodiment of the cleaning and drying apparatus of the present invention, with reference to FIGS. 3 and 13. 
     The cleaning and drying apparatus  18  has a cleaning tank  22  (cleaning chamber) which is filled with a chemical such as hydrofluoric acid and a rinse (cleaning liquid) such as distilled water, where the wafers W are immersed in this chemical and cleaning liquid; and a drying chamber  23  positioned above the cleaning tank  22 . The cleaning and drying apparatus  18  also has a wafer boat  24 , in other words a first holder device, for holding a plurality of wafers W, such as 50 wafers W, and moving them between the cleaning tank  22  and the drying chamber  23 . 
     The cleaning tank  22  has an inner tank  22   a  formed of a material such as quartz or polypropylene and an outer tank  22   b  disposed on the outer side of an upper portion of the inner tank  22   a,  for stopping any overflowing cleaning liquid from the inner tank  22   a.    
     Chemical/cleaning liquid supply nozzles (hereinafter called liquid supply nozzles)  25  are disposed on both sides of a lower portion of the inner tank  22   a,  for ejecting the chemical or the cleaning liquid towards the wafers W positioned within the cleaning tank  22 . The liquid supply nozzles  25  are connected to a chemical supply source and a distilled water supply source (both not shown in the figures), with switching valves therebetween. The chemical or the distilled water are selectively supplied from the liquid supply nozzles  25  to the interior of the cleaning tank  22  for accumulation therein, by switching these valves. 
     An exhaust port is provided in a base portion of the inner tank  22   a  and a drain pipe  26  is connected to this exhaust port with an exhaust valve  26   a  provided therein. An exhaust port that is similarly provided in a base portion of the outer tank  22   b  is connected to a drain pipe  27  with an exhaust valve  27   a  provided therein. Note that an exhaust box  28  is disposed on the outer side of the outer tank  22   b,  and an exhaust pipe  29  is connected to an exhaust port provided in this exhaust box  28  with a valve  29   a  provided therein. 
     The cleaning tank  22  and exhaust box  28  of the above described configuration are disposed within a cylindrical, bottomed box  30 . The box  30  is partitioned horizontally by a dividing plate  31  into an upper chamber  32   a  on the cleaning-tank side and a lower chamber  32   b.  Effluent outlets of the drain pipes  26  and  27  and the exhaust pipe  29 , which are connected to the inner tank  22   a  and the outer tank  22   b,  are positioned in this lower chamber  32   b.  This configuration prevents the atmosphere and droplets of exhaust liquids within the lower chamber  32   b  from entering the upper chamber  32   a,  to maintain the cleanliness of the upper chamber  32   a.  Note that an exhaust window  33  is provided in a side wall of the upper chamber  32   a,  exhaust windows  34  are provided in an upper side wall of the lower chamber  32   b,  and an effluent window  35  is provided in a lower side wall thereof. 
     The drying chamber  23  is defined by an enclosure  23 A made of quartz. This enclosure  23 A is configured of a base element  23   b  acting as a fixed base that has a communicating port  23   a  into the cleaning tank  22 , and first and second enclosing elements  23   c  and  23   d  that act as enclosure halves having a substantially fan-shaped section, as shown in FIGS. 3 and 5. The enclosure halves  23   c  and  23   d  and the base element  23   b  are connected together hermetically by sealing members  36  such as packing or  0 -rings. The enclosure halves  23   c  and  23   d  can be utilized in an engaged state and in a separated state. 
     A stepped portion  23   e  is provided in an engagement surface of an edge portion of one enclosure half  23   c  of these enclosure halves  23   c  and  23   d,  so as to cover the outer side of an edge portion of the other enclosure half  23   d.  A sealing member  37 , such as packing or an  0 -ring, is attached to the engagement surfaces of the enclosure halves  23   c  and  23   d  to obstruct the gap therebetween. 
     The drying chamber  23  of a semicircular cylindrical shape and having an airtight seal is formed by the mutual hermetic engagement between the enclosure halves  23   c  and  23   d  and the base element  23   b.    
     As best shown in FIG. 5 , a guide rail  38  is disposed along one side of the enclosure  23 A, extending in a direction perpendicular to the direction in which the enclosure  23 A opens, in other words, perpendicular to the engagement surfaces of the enclosure halves  23   c  and  23   d.  Two sliders  39  engage in a freely slidable manner with the guide rail  38 . The sliders  39  are linked by connective members  40  to a cylinder body  41   a  and a piston rod  41   b,  respectively, of a horizontal air cylinder  41  that acts as a horizontal-direction drive device. 
     A vertical air cylinder  42  is disposed vertically on an upper portion of each of the sliders  39  to act as a vertical-direction drive device  42 . Free end portions of piston rods  42   a  protruding from the vertical air cylinder devices  42  are connected to the enclosure halves  23   c  and  23   d,  respectively, by substantially L-shaped brackets  43 . 
     An auxiliary guide rail  38   a  that is parallel to the guide rail  38  is disposed along the other side of the enclosure  23 A. The auxiliary guide rail  38   a  also has two sliders  39  engaging therewith in a freely slidable manner. A vertical air cylinder  42  is disposed vertically on an upper portion of each of the sliders  39 . Free end portions of piston rods  42   a  protruding from these vertical movement devices  42  are connected to the enclosure halves  23   c  and  23   d,  respectively, by substantially L-shaped brackets  43 . 
     The above described configuration ensures that the enclosure halves  23   c  and  23   d  move up or down by the action of the vertical air cylinders  42  to move away from or towards the base element  23   b.  The enclosure halves  23   c  and  23   d  can also move sideways by the action of the horizontal air cylinder  41 . 
     As best shown in FIGS. 3 and 4, drying gas supply nozzles  44  are disposed on both sides of an upper portion of the interior of the drying chamber  23 . These nozzles  44  are formed as shower nozzles provided with a plurality of nozzle apertures at a suitable spacing in a nozzle body, as shown in FIG.  4 . The nozzles  44  are connected to a drying gas generator  46  by a supply pipeline  45  that passes through the base element  23   b.    
     The drying gas generator  46  is connected to a source  60  of a liquid for producing a drying gas, such as isopropyl alcohol (IPA), and a source  61  of a carrier gas, such as nitrogen (N 2 ). A switching valve  47  is provided in the supply pipeline  45  so that a drying gas (IPA+N 2 ) generated by the drying gas generator  46  can be supplied into the drying chamber  23  from the nozzles  44  by opening the switching valve  47 . 
     Note that nitrogen alone can be supplied from the drying gas supply nozzles  44  into the drying chamber  23 , by halting the supply of IPA. In that case, the configuration could be such that the opening and closing actions of the switching valve  47  are achieved on the basis of signals from a control means such as a central processing unit (CPU) that is not shown in the figures. 
     An organic solvent such as alcohols such as IPA, or ketones, or ethers, or polyatomic alcohols could be used for the drying gas used in this apparatus. Note that, in such a case, the drying gas could be either an organic solvent such as IPA alone or a mixture of IPA and nitrogen. 
     A shutter  48  is disposed in the communicating portion between the cleaning tank  22  and the drying chamber  23 , to block this communicating portion. This shutter  48  is formed of two shutter halves  48   a  that can move in sideways directions so as to engage and separate, as shown in FIGS. 3 and 4, in a manner similar to that of the enclosure  23 A that defines the drying chamber  23 . 
     The two shutter halves  48   a  are linked together by a cylinder body and a piston rod (not shown in the figure) of a horizontal air cylinder  49  that forms a shutter opening/closing device, in a manner similar to that of the horizontal air cylinders  41 . The shutter halves  48   a  are moved to mutually engage or separate by the action of the horizontal air cylinder  49 , to close or open the communicating portion. A sealing member  50  such as packing is attached to a connective portion of one of the two shutter halves  48   a,  in such a manner that airtightness is maintained when the shutter halves  48   a  are in a connected state, that is, when the shutter  48  is closed. 
     Each of the shutter halves  48   a  is divided into an upper shutter member  48   b  and a lower shutter member  48   c.  The spacing between these shutter members  48   b  and  48   c  in the connection/separation direction (that is, vertically) can be adjusted by a plurality of cylinders  51 , such as eight cylinders  51 , interposed therebetween. This separation of each of the shutter halves  48   a  into an upper shutter member  48   b  and a lower shutter member  48   c  with an adjustable gap therebetween ensures that, when the shutter  48  has been closed, the shutter  48  can be engaged in a hermetic manner against the base element  23   b  of the enclosure  23 A. Thus the cleaning tank  22  and the drying chamber  23  can be reliably isolated. 
     Wing pieces  52  that are bent into a crank-shaped section are provided protruding from both sides of each lower shutter member  48   c  of the shutter halves  48   a.  The wing pieces  52  extend along the direction of movement of the shutter halves  48   a  when they open or close. One of the wing pieces  52  is connected to the horizontal air cylinder  49  for opening and closing the shutter  48 . Bent portions  52   a  of the two wing pieces  52  are immersed in a sealing liquid  54  such as water that fills a trough-shaped tank  53  provided on an upper portion of the cleaning tank  22 . A liquid seal  55  is formed by the bent portions  52   a  of the wing pieces  52 , the trough-shaped tank  53  containing the bent portions  52   a  in a movable manner, and the sealing liquid  54  filling the trough-shaped tank  53 . The atmosphere inside of the cleaning tank  22  and the atmosphere outside thereof are isolated by the liquid seal  55 . 
     Note that, although this is not shown in the figures, the sealing liquid  54  is constantly supplied from a supply port provided in a lower portion of the trough-shaped tank  53  and is also constantly exhausted from an effluent outlet provided in a side portion of an upper portion of the trough-shaped tank  53 , so that clean sealing liquid  54  is continuously replenishing the trough-shaped tank  53 . 
     The cleaning tank  22  and the horizontal air cylinder  49  are separated by a partitioning wall  56 . A lower portion of this partitioning wall  56  is immersed in the sealing liquid  54 , within the bent portions  52   a  of lo the wing pieces  52  positioned in the trough-shaped tank  53 . This makes it possible to ensure that the processing portions within the cleaning tank  22  and the atmosphere on the horizontal air cylinder  49  side are reliably isolated. 
     Note that, the configuration is such that the horizontal air cylinder  49  and the cylinders  51  are driven on the basis of signals from the control portion (the CPU), so that the shutter halves  48   a  can be opened and closed. 
     Note that, the atmospheres of the drying area and the drive side can be reliably isolated by forming the connective members  40  to have bent portions in a similar manner to the wing pieces  52  and by forming a seal by immersing these bent portions in the sealing liquid within the trough-shaped tank. 
     The operation of this cleaning and drying apparatus  18  will now be described with reference to FIGS. 6 to  13 . 
     To convey a plurality of wafers W into the cleaning and drying apparatus, the vertical air cylinders  42  are first driven to raise the enclosure halves  23   c  and  23   d  and thus release their sealed state with respect to the base element  23   b,  as shown in FIG.  6 . 
     The horizontal air cylinders  41  are then driven to move the enclosure halves  23   c  and  23   d  in directions that separate them (see FIG.  7 ). During this time, the wafer boat  24  is raised and moved up to a wafer reception position. 
     In this state, the wafer conveyor chuck  21  holding a plurality of wafers W is lowered through the gap between the released enclosure halves  23   c  and  23   d,  as shown in FIG. 8, to place the wafers W on the wafer boat  24 . The wafer conveyor chuck  21  subsequently opens outward to transfer the wafers W to the wafer boat  24  (see FIG.  9 ). 
     After the wafers W have been transferred to the wafer boat  24 , the wafer conveyor chuck  21  retreats to above the drying chamber  23 , as shown in FIG.  10 . At the same time that the wafer conveyor chuck  21  retreats, the horizontal air cylinders  41  are driven in the opposite direction to that described above, to engage the enclosure halves  23   c  and  23   d.  The vertical air cylinders  42  are then driven in the opposite direction to that described above, to lower the enclosure halves  23   c  and  23   d  into close contact with the base element  23   b.  The wafer boat  24  also lowers to move the wafers W into the cleaning tank  22 . 
     The horizontal air cylinder  49  for opening and closing the shutter is then driven to close the shutter  48 . In this state, the chemical or cleaning liquid, such as distilled water L, is poured in until it overflows, to perform the cleaning, as shown in FIG.  11 . If chemical processing and cleaning are to be performed in sequence, the procedure could be such that the cleaning liquid is supplied from the nozzles after the chemical for the chemical processing has been drained, or the chemical is replaced by the cleaning liquid after the chemical processing. 
     After the cleaning has been completed, the wafer boat  24  is raised to move the wafers W into the drying chamber  23 , and the shutter halves  48   a  close. This occurs before, during, or after the distilled water L within the cleaning tank  22  is discharged from the lower portion of the cleaning tank  22 . 
     Then the drying gas (IPA+N 2 ) is supplied from the drying gas supply nozzles  44  into the drying chamber  23  in this state, as shown in FIG.  12 . The drying gas comes into contact with the surfaces of the wafers W, and thus drying is performed. After the drying, N 2  is supplied instead of the drying gas, completing the drying process. 
     After the drying has been completed, the enclosure halves  23   c  and  23   d  are raised and are also moved in directions to mutually separate them, as shown in FIG. 13, opening the upper portion of the drying chamber  23 . The wafer conveyor chuck  21  then intrudes towards the wafers W held in the wafer boat  24 , to extract and remove the wafers W. After that, the wafer conveyor chuck  21  retreats from within the drying chamber  23  and moves the wafers W on to the next process. 
     As described above, this embodiment of the invention makes it possible to horizontally divide the enclosure  23 A that defines the drying chamber  23 . This make it possible to facilitate the removal and insertion of wafers W within the drying chamber  23 , without increasing the dimensions of the drying chamber  23 . Since this makes it possible to reduce the internal volume of the drying chamber  23 , an improvement in drying efficiency and a decrease in the consumption of drying gas can be achieved. The apparatus itself can also be made more compact. 
     In the abovementioned embodiment, the conveyor chuck  21  inserts the wafers into the drying chamber  23  downwardly from an upper space between the enclosure halves  23   c  and  23   d,  alternatively the conveyor chuck  21  may insert the wafers into the drying chamber  23  sidewardly from a side space between the enclosure halves  23   c  and  23   d.    
     Note that horizontal air cylinders  41  were used in the above embodiment as means for causing the enclosure halves  23   c  and  23   d  to mutually separate in the horizontal direction, but the present invention is not to be taken as limited thereto. In other words, as shown in FIG. 14, the configuration could be such that each of the enclosure halves  23   c  and  23   d  is provided with a vertical cylinder  70 , and a motor  72  is attached to a free end portion of a piston rod  71  of each vertical cylinder  70 . A bracket  73  is attached to the rotational shaft of each motor  72 , and the enclosure halves  23   c  and  23   d  are attached to the corresponding brackets  73 . 
     To open the drying chamber  23  in this case, the vertical cylinders  70  are driven to cause the enclosure halves  23   c  and  23   d  to rise and separate from the base element  23   b.  The motors  72  are then operated to rotate the enclosure halves  23   c  and  23   d  about the centers of the rotational axes of the motors  72 . This configuration makes it possible to move the enclosure halves  23   c  and  23   d  so as to mutually separate horizontally. 
     Second Preferred Embodiment of Cleaning and drying Apparatus 
     The description now turns to a second embodiment of the cleaning and drying apparatus of the present invention, with reference to FIGS. 15 to  25 . 
     FIG. 15 is a cross-sectional view of the cleaning and drying apparatus of this second embodiment and FIG. 16 is a side sectional view thereof. As shown in these figures, the elements configuring a cleaning and drying apparatus  18 ′ of this embodiment are the same as those of the cleaning and drying apparatus  18  of the first embodiment, concerning the cleaning chamber  22  and the box  30 . Identical elements are given the same reference numbers. 
     The description below concerns the configuration of a drying chamber  123 . The drying chamber  123  is defined by an enclosure  123 A which is made of quartz and is U-shaped in section. An aperture  123   a  that communicates with an aperture in an upper portion of the cleaning tank  22 , with a shutter  136  therebetween, is formed in the enclosure  123 A, drying gas supply nozzles  137  are disposed on both sides of an upper portion of the interior of the drying chamber  123 . These nozzles  137  are connected to a drying gas generator  139  by a supply pipeline  138 . The drying gas generator  139  is connected to a source  170  of a liquid for producing a drying gas, such as isopropyl alcohol (IPA), and a source  171  of a carrier gas, such as nitrogen (N 2 ). 
     The ratio of the IPA from the IPA source  170  to the N 2  form the N 2  source  171  is set on the basis of control signals from a control device, such as a CPU  160 . A switching valve  140  is provided in the supply pipeline  138  so that a drying gas (IPA+N 2 ) generated by the drying gas generator  139  can be supplied into the drying chamber  123  from the nozzles  137  by opening the switching valve  140 . An organic solvent such as an alcohol ketone such as IPA, or an ether, or a polyatomic alcohol could be used for the drying gas used in this apparatus. 
     A wafer holder  180  for holding wafers W while they are being dried is provided in the drying chamber  123 . The holder  180  comprises two mutually parallel quartz holder rods  180   a  and  180   b  that act as holding elements. As shown in FIG. 17, each of the holder rods  180   a,    180   b  is formed to have a plurality of grooves  183 , such as  50  grooves, at a suitable spacing in the axial direction thereof. The holder rods  180   a,    180   b  hold the wafers W therebetween by the grooves  183  thereof. 
     The holder rods  180   a  and  180   b  are respectively attached by crank arms  184   a  and  184   b  to end portions of rotational shafts  185   a  and  185   b  within the drying chamber that pass through a side wall of the drying chamber  123 . The rotational shafts  185   a  and  185   b  are respectively attached to mutually engaging gears  186   a  and  186   b,  and one rotational shaft  185   a  is linked to a motor  181  that is capable of rotating in a positive direction. The rotational shafts  185   a  and  185   b  are connected to the side wall of the enclosure  123 A via shaft bearings  182  having a sealing capability, so that the airtight seal of the drying chamber  123  is maintained thereby. 
     This configuration ensures that, if the motor  181  is activated to rotate the rotational shaft  185   a  through a predetermined angle, the rotation of the rotational shaft  185   a  is transmitted to the holder rod  180   a  through the crank arm  184   a,  to cause the holder rod  180   a  to move through an arc in a certain direction, such as clockwise. At the same time, the rotation of the rotational shaft  185   a  is transmitted through the gears  186   a  and  186   b  to cause the rotational shaft  185   b  to rotate in the opposite direction, and this rotation is transmitted through the crank arm  184   b  to cause the holder rod  180   b  to move through an arc in another direction, such as counterclockwise. Therefore, the holder rods  180   a  and  180   b  can selectively adopt either a standby position in which the rods  180   a,    180   b  are spaced apart sidewardly from the wafers W transferred into the drying chamber  123  or a holding position in which the rods  180   a,    180   b  hold the lower side portions of the wafers W (see FIG.  17 ), depending on the direction of rotation of the motor  181 , so that they either release the wafers W or hold them. 
     As shown in FIG. 16, the shutter  136  is divided into an upper shutter member  136   a  and a lower shutter member  136   b,  where the spacing between these shutter members  136   a  and  136   b  in the connection/separation direction (that is, vertically) can be adjusted by a plurality of cylinders  150 , such as eight cylinders  150 , interposed therebetween. This configuration ensures that, when the shutter  136  has been closed, the shutter  136  can be placed in hermetic contact against the enclosure  123 A, so that the cleaning tank  22  and the drying chamber  123  can be reliably isolated. 
     Wing pieces  151  that are bent into a crank-shaped section are provided protruding from both sides along the direction of opening/closing of the lower shutter member  136   b,  and one of these wing pieces  151  is connected to an opening/closing drive device  152  for the shutter  136 . An inert gas such as nitrogen is supplied to the interior of the casing, and bent portions  151   a  of the two wing pieces  151  are disposed in movable manner in a state in which they are immersed in a sealing liquid  154  such as water that fills a trough-shaped tank  153  provided on an upper portion of the cleaning tank  22 . Thus a liquid seal is formed by this embodiment, in a similar manner to that of the first embodiment. 
     The cleaning tank  22  and the drive device  152  are separated by a partitioning wall  156 . A lower portion of this partitioning wall  56  is immersed in the sealing liquid  154 , within the bent portions  151   a  of the wing pieces  151  positioned in the trough-shaped tank  153 , so that the processing portions within the cleaning tank  22  and the atmosphere on the drive device  152  side are isolated. Note that, in this case, the drive device  152  and the cylinders  150  are driven on the basis of signals from the CPU  160 , to open and close the shutter  136 . 
     The operation of this cleaning and drying apparatus will now be described with reference to FIGS. 18 to  21 . 
     Cleaning 
     After wafers W have been accommodated within the cleaning tank  22  with the shutter  136  open, the shutter  136  is closed as shown in FIG.  18  and distilled water L is poured in until it overflows, to perform the cleaning. 
     Drying 
     After the cleaning, the shutter  136  is opened and the wafer boat  24 , is raised to move the wafers W into the drying chamber  123 , as shown in FIG.  19 . During this time, the distilled water L still pours into the cleaning tank  22  and is exhausted therefrom. 
     The shutter  136  is then closed and the motor  181  is driven so that a portion of the wafers W that differs from the portion thereof in contact with the wafer boat  24  is held by the holder rods  180   a  and  180   b  of the holder  180 , as shown in FIG.  20 . During this time, the wafers W are held by the holder  180  and the wafer boat  24  is moved downward simultaneously, so that the holding of the wafers W thereby is released. 
     The drying gas (IPA+N 2 ) is then supplied to the interior of the drying chamber  123  from the drying gas supply nozzles  137 , as shown in FIG. 21, so that any moisture remaining on the wafers W due to the distilled water L and condensed cleaning gas is removed therefrom, drying the surfaces of the wafers W. Nitrogen alone is then supplied to complete the drying step. 
     Note that after the wafer boat  24  is raised and the wafers W have been moved into the drying chamber  123 , but before the wafers W are transferred to the holder  180 , a preliminary drying could be performed with the wafers W still held by the wafer boat  24 . 
     In this drying step, the wafers W are transferred from the wafer boat  24  to the holder  80  within the drying chamber  123  in such a manner that contact portions therebetween are different, thus solving the problem of bad drainage at the contact portions and also making it easier for the drying gas to come into contact with those portions. Therefore, the drying time can be reduced and also the consumption of drying gas can be decreased, thus making it possible to expect an improvement in drying efficiency. It is also possible to reduce unevenness in the drying, enabling an increase in yield. The start time for the next wash can also be reduced by exchanging the cleaning liquid in the cleaning tank  22  during the drying step. 
     The description now concerns an altanative operation of this cleaning and drying apparatus, with reference to FIGS. 22 to  26 . 
     Cleaning 
     The procedure for this cleaning step is the same as that described above (see FIG.  22 ). 
     First Drying Step 
     After the cleaning shown in FIG. 22, the shutter is opened and the wafer boat  24  is raised to move the wafers W into the drying chamber  123 , as shown in FIG.  23 . The shutter  136  is then closed and the motor  181  is driven so that the wafers W are held by holder rods  180   a  and  180   b  of the holder  180  at portions that differ from the portions thereof in contact with the wafer boat  24 , as shown in FIG.  24 . Simultaneous with the holding of the wafers W by the holder  180 , the wafer boat  24  is moved downward to release the holding of the wafers W, the drying gas is supplied to the interior of the drying chamber  123  from the drying gas supply nozzles  137 , as shown in FIG. 25, and thus any moisture remaining on the wafers W due to the distilled water L and condensed cleaning gas is removed therefrom, drying the surfaces of the wafers W. 
     Note that after the wafer boat  24  is raised and the wafers W have been moved into the drying chamber  123 , but before the wafers W are transferred to the holder  180 , a preliminary drying could be performed with the wafers W still held by the wafer boat  24 . 
     Second Drying Step 
     Once the surfaces of the wafers W have been dried by the first drying step, the wafer boat  24  is raised from a standby position separated from the wafers W, to come back into contact with the wafers W and hold them. Simultaneously therewith, the holding of the wafers W by the holder  180  is released, and the supply of drying gas into the drying chamber  123  from the drying gas supply nozzles  137  is continued without change (see FIG.  26 ). 
     The drying process could be completed by supplying N 2  alone instead of the drying gas after the second drying step. 
     In this second drying step, the wafers that had been transferred from the wafer boat  24  to the holder  180  during the first dying step are transferred back from the holder  180  to the wafer boat  24 , so that if there should be any moisture at portions held by the holder  180 , the problems of bad drainage and the bad contact efficiency of the drying gases at those portions can be solved. It is therefore possible to shorten the drying time even further, reduce the consumption of drying gas, improve the drying efficiency even further, and also further solve the problem of unevenness of drying, thus increasing the yield even further. 
     Note that the start time for the next wash can also be reduced by exchanging the cleaning liquid in the cleaning tank  22  during the drying step. Note also that the timing at which the drying gas is supplied could be before the wafers W are moved into the drying chamber  123 . The first and second embodiments were described above as relating to the application of the cleaning and drying apparatus of the present invention to a cleaning and drying system for semiconductor wafers, but it should be obvious that this invention can also be applied to processing systems other than cleaning and drying systems, and it can be applied to objects to be processed other than semiconductor wafers, such as glass LCD substrates.