Abstract:
A cleaning method is provided for cleaning a semiconductor wafer. In this method, after removing adhering substances from the wafer by using a chemical liquid of organic amine type, there is carried out a pure-water cleaning capable of prevention of electrostatic destruction and alkaline corrosion on the wafer. In detail, it is executed to make a processing chamber have an atmosphere of carbon dioxide and subsequently introduce steam into the chamber to dissolve CO 2 -gas into the steam. Next, spray the pure water to the wafer. Then, the steam in which CO 2 -gas is dissolved dissolves in the pure water, so that the pure wafer becomes weak acid, accomplishing the reduction of resistivity of the pure water. Additionally, alkaline substances is neutralized by carbonated water to prevent an alkaline corrosion on a wiring layer on the wafer&#39;s surface.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a cleaning method of cleaning substrates of various kinds, such as semiconductor wafers and LCD substrates, by a processing liquid and also relates to a cleaning apparatus for carrying out the above cleaning method. 
     2. Description of the Related Art 
     In the manufacturing process of the semiconductor devices, the semiconductor wafers as the substrates are processed by a processing liquid, such as designated chemical liquids and pure water, in order to remove contaminations (e.g. particles, organic contaminants and metallic impurities), organic substances and oxidization films, out of the wafers. 
     When carrying out this cleaning process by using the pure water, there is used CO 2  injection water of which resistivity is lowered by dissolving carbon dioxide (CO 2 ) gas into the pure water, in order to avoid the generation of static electricity during the cleaning process, which might cause discharge breakdown on the wafers. 
     The CO 2  injection water is produced, for example, by allowing carbon dioxide through filters, such as counter-permeable membrane, to dissolve carbon dioxide into the pure water. 
     During the production of the CO 2  injection water, the resistivity of the finished CO 2  injection water is always measured and further the so-measured value is fed back for the present dissolution control of carbon dioxide to attain a designated resistivity of the water. 
     However, when the cleaning apparatus is equipped with such a production unit of the CO 2  injection water, there come into existence problems that the installation cost is elevated and the apparatus itself is large-sized, due to the establishment of additions, for example, filters, a resistivity meter, a feedback unit, etc. From this point of view, it is deemed that a more simple and convenient method of allowing the resistivity of pure water to be reduced is desirable to restrict the occurrence of static electricity for prevention the discharge breakdown on the wafers. 
     Meanwhile, in the cleaning process using various chemical liquids preceding the cleaning step using the pure water, there is a case of using a chemical liquid of organic-amine type. In this particular case, alkaline substances are produced after the cleaning process of the pure water following the cleaning process using the chemical liquid of organic-amine type, due to the reaction of the chemical liquid with the pure water. Unfortunately, the alkaline substances erode aluminum wiring on the wafers. In this view, it is also desired to prevent the generation of alkaline substances derived from the reaction of the chemical liquid with the pure water. 
     Hereat, it is noted that the manufacturing process of semiconductor wafers comprises the following steps of: forming oxidation layers (SiO 2 ), nitride layers (SiN), metal layers (Cu) or the like on the wafers; applying resists on the wafers; exposing a designated pattern to each resist on the wafers and next developing the resist by developer; dry-etching oxidation layers (SiO 2 ), nitride layers (SiN), metal layers (Cu) or the like; cleaning the wafers by a chemical liquid, such as organic solvent, organic acid, inorganic acid, etc. (for removal of residuals, e.g. polymers); and finally rinsing the used chemical liquid from the wafers, in that order. 
     As to the method of cleaning the wafers by the chemical liquid, there is a known method of supplying the chemical liquid to the rotating wafers. Here, it should be noted that there exist linear grooves and holes on the wafer surface, which are resulting from the etching step. Since there is a difference between flat potions on the wafer surface and the grooves/holes thereon in respect of the flowing condition of the chemical liquid, it is impossible to remove polymers sticking to the wafer perfectly in the conventional method. For this reason, it requires a long period for the chemical-processing process, causing the reduction of throughput. 
     SUMMARY OF THE INVENTION 
     Accordingly, the first object of the present invention is to provide a method for dissolving carbon dioxide in the pure water for cleaning substrates with ease and convenience. 
     The second object of the present invention is to provide a method for restricting the generation of alkaline substances resulting from the reaction of a chemical liquid of organic-amine type with the pure water in the cleaning process for the substrates. 
     The third object of the present invention is to provide a method of cleaning a surface of the substrate having grooves and holes formed thereon, effectively. 
     In order to accomplish the above objectives, the present invention provides a method of cleaning a substrate in a processing chamber, which includes the steps of: (a) introducing carbon dioxide gas into the processing chamber, thereby making an atmosphere of carbon dioxide concentration being greater than that of air in the processing chamber; and (b) spraying the substrate with pure water while rotating the substrate in the processing chamber having the atmosphere of carbon dioxide. 
     The present invention also provides a substrate cleaning apparatus, which includes: a substrate holder that holds a substrate; a motor that rotates the substrate holder; an enclosure defining a processing chamber therein, the processing chamber being capable of accommodating the substrate holder; a carbon dioxide gas supply system that supplies carbon dioxide gas into the processing chamber; and a pure water supply nozzle that sprays the substrate accommodated in the processing chamber with pure water. 
     In addition, the present invention also provides a method of cleaning a substrate, which includes the steps of: (a) supplying the substrate with a chemical liquid for dissolving unnecessary substances sticking to the substrate while rotating the substrate at a first rotating speed; (b) supplying the substrate with the chemical liquid while rotating the substrate at a second rotating speed greater than the first rotating speed; and (c) stopping supplying the chemical liquid and rotating the substrate at a third rotating speed greater than the second rotating speed. 
     Furthermore, the present invention also provides a substrate cleaning apparatus, which includes: a substrate holder that holds a substrate; a motor that rotates the substrate holder; a nozzle that sprays the substrate with a chemical liquid for dissolving unnecessary substances sticking to the substrate; and a controller that controls a rotation of the motor and an ejection of the chemical liquid from the nozzle according to a routine including the steps of: (a) supplying the substrate with the chemical liquid while rotating the substrate at a first rotating speed; (b) supplying the substrate with the chemical liquid while rotating the substrate at a second rotating speed greater than the first rotating speed; and (c) stopping supplying the chemical liquid and rotating the substrate at a third rotating speed greater than the second rotating speed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing the first embodiment of a cleaning apparatus of the present invention; 
     FIG. 2 is a plan view showing the cleaning apparatus of FIG. 1; 
     FIG. 3 is a sectional view showing a cleaning unit of the cleaning apparatus of FIG. 1; 
     FIG. 4 is a sectional view showing a condition that an inner cylinder is withdrawn from an outer cylinder of the cleaning unit of FIG. 3; 
     FIG. 5 is a sectional view showing a condition that the inner cylinder is arranged inside the outer cylinder of the cleaning unit of FIG. 3; 
     FIGS. 6A and 6B are perspective views of ejection nozzles of FIGS. 4 and 5 of the other embodiments; 
     FIGS. 7A and 7B are front and side views of the outer cylinder showing the arrangement of nozzles for water/steam; 
     FIG. 8 is a structural diagram showing the structure of a CO 2  gas supply system and a water/steam supply system; 
     FIG. 9 is a schematic diagram showing the structure of the cleaning apparatus of the second embodiment of the invention; 
     FIG. 10 is a flow chart showing a series of steps of the cleaning process of the invention; 
     FIG. 11 is a process diagram showing the steps of the cleaning process; 
     FIG. 12 is a graph showing a relationship between revolutions of the wafer and ejecting conditions of the chemical liquid in the cleaning process; 
     FIG. 13A is a sectional view showing a contact condition between polymer sticking to the surface of the wafer and the chemical liquid; 
     FIG. 13B is a sectional view taken along a line A—A of FIG. 13A; 
     FIG. 14 is a schematic plan view showing the structure of the cleaning apparatus of the third embodiment of the invention; 
     FIG. 15 is a schematic structural view of the cleaning apparatus of FIG. 14; 
     FIG. 16 is a sectional view of an essential part of the cleaning apparatus of FIG. 14; and 
     FIG. 17 is a view showing a piping system of the cleaning apparatus of FIG.  14 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to attached drawings, embodiments according to the present invention will be described below. 
     [1st. Embodiment] 
     The first embodiment will be explained while taking example by a cleaning apparatus for consistently loading, washing, drying and unloading semiconductor wafers in batch. Note, the semiconductor wafers will be referred as “wafers”, hereinafter. FIG. 1 is a perspective view of the cleaning apparatus and FIG. 2 is a plan view of the cleaning apparatus. As shown in FIGS. 1 and 2, the cleaning apparatus  1  includes an in/out port (container loading/unloading section)  2  for loading and unloading carriers (substrate container) C capable of accommodating the wafers W therein, a cleaning unit  3  for performing a cleaning process against the wafers W, a stage section  4  disposed between the in/out port  2  and the cleaning unit  3  to load the carriers C into the cleaning unit  3  and also unload the carriers C therefrom, a carrier cleaning unit  5  for cleaning the carriers C and a carrier stocking unit  6  for stocking a plurality of carriers C. Note, reference numeral  7  designates a power unit and reference numeral  8  designates a chemical tank box. 
     The in/out port  2  is provided with a mount table  10  allowing four carriers C to be mounted thereon and a carrier conveyer mechanism  12  capable of moving along a conveyer path  11  defined along the arrangement direction of the carriers C. The carrier conveyer mechanism  12  shuttles the carrier C between the mount table  10  and the stage section  4 . The carrier C is capable of accommodating the wafers W of the plural number, for example, twenty-six wafers W in the vertical arrangement. 
     The stage section  4  is provided with a stage  13  for mounting the carrier C thereon. The carrier C is transported between the cleaning unit  3  and the stage  13  by a carrier conveyer mechanism having an actuating cylinder. On the stage  13 , there is also provided a reverse mechanism (not shown) for reversing the carrier C. The reason why the stage  13  has the reverse mechanism is that, since the carrier conveyer mechanism  12  after receipt of the carrier C from the mount table  10  transfers the carrier C to the stage  13  while rotating its arm (not shown), the direction of the carrier C on the stage  13  is opposite to that of the carrier C on the table  10 . 
     A partition wall  14  is arranged between the stage section  4  and the cleaning unit  3 . The partition wall  14  has an opening  14   a  formed to load/unload the carrier C therethrough. The opening  14   a  can be closed by a shutter  15 . During processing the wafers W in the cleaning unit  3 , the shutter  15  is closed. When loading the carrier C into the unit  3  and unloading the carrier C out of the unit  3 , the shutter  15  is opened. 
     The carrier cleaning unit  5  is equipped with a carrier cleaning bath  16 . In the carrier cleaning bath  16 , the carrier C emptied as a result of taking out the wafers W at the cleaning unit  3  is cleaned. 
     The purpose of provision of the carrier stocking unit  6  is to make the carrier C having the uncleaned wafers W or the emptied carrier C after taking out the uncleaned wafers W wait for the next-coming process temporarily. Also, the same unit  6  is provided to make the emptied carrier C to wait in advance of accommodating the cleaned wafers W. The interior of the carrier stocking unit  6  is capable of stocking a plurality of carriers C vertically. Further, the carrier stocking unit  6  is provided with a carrier moving mechanism. The carrier moving mechanism capable of placing the carrier C in the carrier stocking unit  6  on the carrier conveyer mechanism  12  and also capable of transferring the carrier C to a designated position in the carrier stocking unit  6 . 
     Next, the cleaning unit  3  will be described. FIG. 3 is a sectional view showing the interior of the cleaning unit  3 . FIGS. 3 and 4 are sectional views both showing a cleaning part of the cleaning unit  3 . In detail, FIG. 4 illustrates a condition that an inner cylinder  27  is withdrawn out of an outer cylinder  26 . Note, this position of the inner cylinder  27  will be called “retracted position” hereinafter. On the other hand, FIG. 5 illustrates another condition that the inner cylinder  27  is arranged inside the outer cylinder  26 . This position of the cylinder  27  will be called “processing position” hereinafter. 
     Inside the cleaning unit  3 , there are arranged, as shown in FIG. 3, a cleaning section  20 , a carrier standby (waiting) section  30  and a wafer moving mechanism  40 . 
     The carrier standby section  30  has a stage  31  arranged just below a rotor  24 . A carrier conveyer mechanism  35  transfers the carrier C between the stage  13  of the stage section  4  and the stage  31  of the carrier standby section  30 . The carrier conveyer mechanism  35  has a base member  34  bridging between the stage  13  and the stage  31 , guide rails  33  on the base member  34  and a slidable stage  32  moving between the stage  13  and the stage  31  along the guide rails  33 . The carrier c on the slidable stage  32 , which has been loaded from the stage section  4  into the carrier standby section  30 , stops at a position on the stage  31  and stands ready there. 
     The wafer moving mechanism  40  has a wafer holding member  41  for holding the wafers W, a supporting rod  42  for supporting the wafer holding member  41  and an elevator unit  43  for moving the wafer holding member  41  up and down through the supporting rod  42 . By rising the wafer holding member  41  by the elevator unit  43 , the wafers W at the carrier standby section  30  can be transferred between the carrier C at the carrier standby section  30  and the rotor  24  of the cleaning section  20 . 
     For the purposed of holding the wafers W, grooves are formed on the wafer holding member  41  at predetermined intervals. The number of grooves is twice as many as the number of wafers (e.g. fifty-two grooves) that the carrier C can accommodate. These grooves are provided for holding the uncleaned wafers W and the cleaned wafers W alternatively. 
     A wafer detector  99  is arranged between the cleaning section  20  and the carrier standby section  30 , in detail, besides the transfer route of the wafers W where they are transferred between the carrier C on the stage  31  and the rotor  24  by the wafer holding member  41 . The wafer detector  99  includes a plurality of optical sensors each consisting of a pair of emitter and receptor interposing the transfer route of the wafers W therebetween. When the wafers W pass through the wafer detector  99 , it confirms the number of wafers W and the presence of so-called “jump-slot” condition that at least one wafer is carried in the carrier C inappropriately or dropped from the carrier C. 
     The cleaning section  20  serves to remove resist-mask, polymer layer as etching residual, etc. from the wafers W after the etching process. Besides the above rotor  24 , the cleaning section  20  is provided with a vertical support wall  18  and a motor  23  fixed on the support wall  18 . The motor  23  has a horizontal rotating shaft  23   a  to which a rotor  24  is secured. The rotating shaft  23   a  is surrounded by a support cylinder  25 . 
     The rotor  24  has a pair of circular plates  70   a  and  70   b . The circular plate  70   b  is fixed on the rotating shaft  23   a  of the motor  23 . A gap between the circular plates  70   a  and  70   b  is bridged by first immovable support rods  71   a ,  71   b  ( 71   b : not shown because of back of the rod  71   a ), and second immovable support rods  72   a ,  72   b  ( 72   b : not shown because of back of the rod  71   a ). The rotor  24  further includes movable (rotatable) support rods  83   a ,  83   b  ( 83   b : not shown because of back of the rod  83   a ). Owing to the provision of these support rods, the rotor  24  is capable of carrying a plurality (e.g. 26 pieces) of wafers W in the vertical arrangement and also in the horizontal direction at regular intervals. 
     The outer cylinder  26  and the inner cylinder  27  are movably attached to the support cylinder  25  so as to surround the rotor  24  to define a processing chamber in the cylinders. The inner cylinder  27  has a diameter smaller than that of the outer cylinder  27 . The outer cylinder  26  is movable between the processing position (shown with chain double-dashed lines of FIG. 3) and the standby position (shown with solid lines of FIG.  3 ). The inner cylinder  27  is movable between the processing position shown in FIG.  5  and the standby position outside the support cylinder  25  shown in FIGS. 3 and 4. 
     When loading the wafers W into the rotor  24  or unloading the wafers W therefrom, both of the cylinders  26 ,  27  are positioned at the standby position, as shown in FIG.  3 . As shown in FIG. 4, when the outer cylinder  26  is positioned at the processing position and the inner cylinder  27  is positioned at the standby position, a first processing chamber  51  is defined by the outer cylinder  26 , a vertical wall  26   a  closer to the motor  23  and another vertical wall  26   b  closer to the leading end of the rotor  24  (see FIG.  4 ). As shown in FIG. 5, when the inner cylinder  27  (and the outer cylinder  26 ) are positioned at the processing position, a second processing chamber  52  is defined by the inner cylinder  27  and the vertical walls  26   a ,  26   b.    
     The vertical wall  26   a  is attached to the support cylinder  25 . A bearing  28  is arranged between the support cylinder  25  and the rotating shaft  23   a . The vertical wall  26   a  and the leading end of the cylinder  25  are sealed up with a labyrinth seal  29  in order to prevent particles of the motor  23  from invading the processing chamber  51 . The support cylinder  25  is provided, on its end closer to the motor  23 , with an engagement member  25   a  engageable with the outer cylinder  26  and the inner cylinder  27 . Note, the processing chambers  51 ,  52  provide closed spaces by means of not-shown seal mechanisms. 
     Attached to the vertical wall  26   b  are a discharging nozzle  54 , which has a number of ejecting orifices  53  juxtaposed in the horizontal direction. The nozzles  54  are capable of ejecting processing liquids (e.g. pure water, IPA, chemical liquids) and various gases (e.g. CO 2  gas, N 2  gas, a mixture of CO 2  and N 2 ) supplied from not-shown fluid sources. 
     Fixed to the inside upper part of the inner cylinder  27  is a discharging nozzles  56 , which have a number of ejecting orifices  55  juxtaposed in the horizontal direction. The nozzles  56  are capable of ejecting processing liquids (e.g. pure water, IPA, various chemical liquids), CO 2  gas, N 2  gas, etc. supplied from not-shown fluid sources. 
     The discharging nozzles  54  and  56  are made of fluorinated resin, for example, PTFE, PFA or stainless steel. Note, the nozzles  54 ,  56  may be replaced by two or more nozzles, respectively. 
     Without being limited to the structures schematically shown in FIGS. 3 to  5 , the discharging nozzle may be provided with the structures shown in FIGS. 6A and 6B. As shown in FIG. 6A, a discharging nozzle  54   a  is provided, on one face thereof, with a plurality of nozzle tips  91   a ,  91   b . The nozzle tips includes the nozzle tips  91   a  of the number (twenty-six) equal to the number of wafers W that the rotor  24  can retain and two nozzle tips  91   b  arranged on both ends of the group of nozzle tips  91   a . The discharging nozzle  54   a  further includes a supply pipe  92  attached to the back of the nozzle  54   a  to supply the processing liquid. The nozzle is fixed to the outer cylinder  26 . In such a case, a rectangular hole, which has a shape corresponding to the outer shape of the nozzle  54   a , is formed through the cylinder, and the nozzle  54   a  is fixed to the outer cylinder  26  with the nozzle  54   a  being fitted in the hole. 
     An ejection orifice  53   a  of each nozzle tip  91   a  is so designed that the processing liquid ejected therefrom fans out in plane to strike on the single wafer W in charge of the nozzle tip  91   a  at an angle with the wafer&#39;s face to be processed. In each nozzle tip  91   b , the processing liquid ejected from the ejection orifice  53   a  operates to control the track of the processing liquid ejected from the adjacent nozzle tip  91   a  so that the processing liquid sticks on a designated area on the wafer W. If the nozzle tips  91   b  were not provided for the nozzle  54   a , the tracks of the processing liquid ejected from the outermost nozzles tips  91   a  would be curved out of the target areas of the wafers W. 
     In the nozzle  54   a  of FIG. 6A, the nozzle tips  91   a ,  91   b  are positioned in zigzags in view of allowing the tips  91   a ,  91   b  of the shown size to correspond to the intervals of the wafers W retained in the rotor  24 . Therefore, if adopting nozzle tips different from the shown tips  91   a ,  91   b  in configuration, then it is possible to align the so-shaped nozzle tips on the discharging nozzle. In such a case, the discharging nozzle will become slimmer than the shown nozzle  54   a . Then, the arrangement space required for the discharging nozzle  54   a  can be reduced to miniaturize the outer cylinder or the inner cylinder. 
     A discharging nozzle  54   b  shown in FIG. 6B has a number of ejecting orifices  53   b  formed in a nozzle body  93 , provided with no nozzle tip. In the nozzle  54   b , because of the reduced intervals of the ejecting orifices  53   b , it is easy to arrange the ejecting orifices  53   b  in a row. Owing to the removal of the nozzle tips, it is possible to simplify and miniaturize the structure of the discharging nozzle  54   b . It is noted that the discharging nozzle  54   b  is also provided with twenty-eight ejecting orifices  53   b . Two orifices on both sides of the ejecting orifices  53   b  in a row are provided for the same purpose as that of two orifices on both sides of the aforementioned ejecting nozzle  54   a.    
     In the processing chambers  51 ,  52 , there may be provided other discharging nozzles in addition to the discharging nozzles  54 ,  56 , respectively. In such a case, the provided discharging nozzles may be provided with structures different from those of the discharging nozzles  54 ,  56  on consideration of the kinds of processing liquids. 
     Inside the top of the inner cylinder  27 , discharging nozzles  75   a ,  75   b  are arranged to clean the inside faces of the circular plates  70   a ,  70   b  opposing the wafers W. The vertical walls  26   a ,  26   b  have discharging nozzles  74   b ,  74   a  arranged to clean the respective faces of the plates  70   b ,  70   a  opposing the vertical walls  26   a ,  26   b , respectively. Mainly, these discharging nozzles  74   a ,  74   b ,  75   a ,  75   b  are used to rinse the circular plates  70   a ,  70   b  (after various chemical-processing treatment) by the pure water. 
     On the lower part of the vertical wall  26   b , a first drain port  61  is provided to drain the chemical liquids, the pure water and IPA (after use) from the processing chamber  51  of FIG.  4 . Above the first drain port  61 , a second drain port  62  is arranged to drain the so-used chemicals, the pure water and IPA from the processing chamber  52  of FIG.  5 . The first drain port  61  and the second drain port  62  are connected to a first drain pipe  63  and a second drain pipe  64 , respectively. 
     On the upper part of the vertical wall  26   b , a first exhaust port  65  is arranged to exhaust the processing chamber  51  under the condition of FIG.  4 . Under the first exhaust port  65 , a second exhaust port  66  is arranged to exhaust the processing chamber  52  in the condition of FIG.  5 . The first exhaust port  65  and the second exhaust port  66  are connected to a first exhaust pipe  67  and a second exhaust pipe  68 , respectively. 
     The vertical wall  26   b  has an extension wall formed to extend from the periphery of the wall  26  in the axial direction of the rotor  24  (see FIGS.  4  and  5 ). At the top part of the extension wall, a gas supply port  76  is formed to supply CO 2  gas. A gas supply pipe  77  is connected with the gas supply port  76 . In the modification of the arrangement of FIGS. 4 and 5, the gas supply port  76  may be arranged in the vertical wall  26   b , for example. CO 2  gas is supplied from a CO 2  gas supply system  80 , which is shown in FIG. 8, to the gas supply port  76 . 
     The outer cylinder  26  has a plurality of water/steam supply nozzle  78  attached to supply the interior of the processing chamber  51  with the pure water in the form of mist (simply referred as “water mist”, hereinafter) and the vapor of pure water (simply referred as “steam”, hereinafter). As shown in FIGS. 7A and 7B, there are provided the nozzles  78  of the plural number (12 pcs. in this embodiment). Nevertheless, single nozzle  78  is shown in FIGS. 4 and 5 for simplification of the drawings. The nozzles  78  are decentralized so that water mist or steam ejected therefrom spreads the surroundings of each wafer W uniformly. Water or steam is supplied to the nozzles  78  by a water/steam supply system  90 . 
     FIG. 8 illustrates a CO 2  gas supply system  80  connected to the gas supply port  76  and the water/steam supply system  90  connected to the nozzles  78 . The CO 2  gas supply system  80  has a CO 2  gas source (CO 2  gas cylinder)  81 , a pressure meter  82  for monitoring the pressure of the source  81 , a pressure regulating valve  83 , a flow meter  84 , an open/close valve  85  and a filter  86  in sequence. 
     The water/steam supply system  90  has a pure water container  91  whose periphery is equipped with a heater  91   a . The pure-water container  91  is provided with a level meter  91   b  and a drain  91   c . A pure water line  91  and a carrier gas line  93  for supplying N 2  gas as carrier gas are connected with the pure water container  91 . The carrier gas line  90  has a N 2  gas source  93   a , a pressure regulating valve  93   b , a flow meter  93   c , an open/close valve  93   d  and a filter  93   e  in sequence. The pure water in the container  91  is heated into steam by a heater  91   a . The steam is carried into a steam line  94  by the carrier gas. A pure water line  95  joins the steam line  94 . The steam line  94  and the pure water line  95  have open/close valves  94   a ,  95   a , interposed therein, respectively. The manipulation of the valves  94   a ,  95   a  allows the steam or pure water to be supplied to the nozzles  78  selectively. Each nozzle  78  has a built-in ultrasonic oscillator (not shown). The ultrasonic oscillator changes the pure water (liquid) supplied from the pure-water line  95  into fine waterdrops (making mist). When the pure water (liquid) is supplied to the nozzles  78 , they spray the pure water so as to spread in a conical manner. 
     Next, we describe a method of cleaning the wafer W while using the above-mentioned cleaning apparatus  1 . First, it is carried out to mount the carrier C in which the wafers W to be processed are accommodated, on a predetermined position of the mount table  10 . Then, the carrier conveyer mechanism  12  conveys the carrier C to the stage section  4 . The carrier C is mounted on the slide stage  32  standing ready on the stage  13  of the stage section  4 . Next, the slide stage  32  is moved onto the stage  31  of the carrier standby section  30 . It is executed to position the outer cylinder  26  and the outer cylinder  27  in their standby positions. Upon raising the wafer holding member  41  by the elevator unit  43 , the wafers W are taken out of the carrier C and moved into the rotor  24  of the cleaning section  20 . After the wafer W are held by the rotor  23 , the wafer holding member  41  is lowered, 
     Next, the outer cylinder  26  and the inner cylinder  27  are shifted to the processing positions to define the processing chamber  52  in the inner cylinder  27 . Then, the rotor  24  holding the wafers W is rotated by the motor  23 . It is executed to allow the nozzle  56  to eject a designated chemical liquid while rotating the wafers W thereby to remove resists on the wafers W. This operation is carried out one time or several times. 
     Next, the inner cylinder  27  is slid to the standby position to define the processing chamber  51  of the outer cylinder  26 . Under such a situation, it is first carried out to perform the cleaning process. In the cleaning process, an CO 2  gas-enriched atmosphere is established in the processing chamber  51 . The resistivity of the pure water, which contacts with the wafer and CO 2  gas is dissolved therein, is, preferably, 0.2 M cm or less. The required CO 2  gas concentration in the processing chamber, in order to achieve the preferable resistivity of the pure water, varies depending on the way how to feed CO 2  gas into the processing chamber  51  and depending on the routines of the cleaning process (see routines (1) to (4) mentioned later), however, the CO 2  gas concentration in the processing chamber should be greater than that in the air, preferably 20 vol % or greater. In this state, the pure water for rinsing is ejected from the nozzle  54  while rotating the rotor  24  holding the wafers W by the motor  23 . 
     In case of the cleaning process under the above conditions, the ejected pure water comes into contact with CO 2 -gas in the atmosphere and subsequently strikes against the wafers W while the resistivity of pure water is lowered as a result of the solution of CO 2 -gas in the pure water. Therefore, since the occurrence of static electricity is restricted, it is possible to prevent the discharge breakdown on the wafers W. 
     It is noted that the pure water having CO 2 -gas dissolved therein represents weak acidity. Here, when the cleaning process using the pure water follows the cleaning process using the chemical liquid of organic-amine type, alkaline substances are produced. It is likely that the alkaline substances shall have damage on various circuits built on the wafers W. 
     According to the present method, however, there is no possibility of such a problem since the alkaline substances are neutralized by the above pure water having CO 2  gas dissolved therein. 
     Without increasing the manufacturing cost and size, the cleaning apparatus of this embodiment can take effect similar to that of the other cleaning apparatus equipped with an exclusive unit for producing CO 2  injection water. 
     As the concrete steps to perform the cleaning process using the pure water under the CO 2  gas-enriched atmosphere, there can be expected the following routines (1) to (4): 
     (1) Supply the processing chamber  51  with CO 2  gas through the nozzle  54 , and subsequently eject the pure water through the nozzle  54 . Note, since no CO 2  gas is supplied during the ejection of pure water, it is unavoidable that the concentration of CO 2  gas in the processing chamber  51  is gradually reduced in the course of process. In this view, it is desirable to establish the concentration of CO 2  gas relatively high at the start of cleaning process in order to ensure the atmosphere of CO 2  gas more than a predetermined concentration at the end of the cleaning process. 
     (2) Eject CO 2  gas and the pure water through the nozzle  54  simultaneously. In this case, it is appropriate to eject CO 2  gas prior to the ejection of pure water and subsequently eject CO 2  gas and the pure water through the nozzle  54  simultaneously. Then, there is no need of contrivance to facilitate dissolution of CO 2  gas into the pure water in advance of ejecting from the nozzle  54 , for example, the provision of a filter in a CO 2  gas injection water maker. In this case, however, the discharging nozzle  54  ejects the pure water containing air bubbles. Therefore, it is necessary to appropriately adjust the ejection ratio of pure water to gas in quantity and the mixing condition between pure water and gas so that the configuration of the pure water ejected from the nozzle  54  is not disturbed. 
     (3) Eject the pure water from the nozzle  54  while supplying gas containing CO 2  gas from the gas supply port  76 . According to this method, it is possible to avoid the problems that might be caused in the above cases (1) and (2). In this case, it is desirable that, for example, CO 2  gas is introduced into the processing chamber  51  at the flow rate of 0.4 to 0.5 liter per minute thereby to establish a condition where a predetermined concentration of CO 2  gas exists in the processing chamber  51  prior to the ejection of pure water. 
     Continuously, the ejecting of pure water from the nozzle  54  and the exhausting through the first exhaust port  65  are carried out while maintaining the supply of gas containing CO 2 -gas and rotating the rotor  24  having the wafers W. According to this method, the cleaning process can be accomplished while establishing a constant concentration of CO 2 -gas in the processing chamber  51 . 
     (4) Fill up the processing chamber  51  with the gas containing CO 2 -gas and subsequently supply the chamber  51  with water mist or steam via the water/steam nozzle  78  thereby to dissolve CO 2 -gas in the mist or steam. Thereafter, any one of the steps (1) to (3) is performed. In this case, without being blown against the wafers W vigorously, the water mist or steam is supplied from the nozzle  78  so as to float in the circumference of the wafers W. The CO 2 -gas is easy to dissolve in the water mist or the water vapor, particularly, steam. The water mist or steam having CO 2 -gas dissolved therein comes in contact with the pure water ejected from the discharging nozzle  54 , for a mixture. According to this method, it is possible to effectively dissolve CO 2 -gas in the pure water in comparison with the method of directly dissolving CO 2 -gas in the pure water ejected from the discharging nozzle  54 . 
     It is also advantageous to allow the surfaces of the wafer W to directly contact CO 2 -gas at periodical standstills of the pure-water supply in the cleaning process. Then, the ejected pure water strikes against the wafers W while or after involving CO 2 -gas on the surfaces of the wafers W. In the above-mentioned cleaning apparatus  1 , it is easy to stop the supply of pure water temporarily. Further, it is easy to establish the exposed surfaces of the wafers W by rotating the rotor at a high speed at the standstill of water supply thereby to shake the pure water or chemical residuals off the surfaces of the wafers W. 
     After completing the rinsing process, it is executed to eject N 2 -gas from the nozzle  54  and rotate the rotor  24  at a higher speed than that of the chemical cleaning process or the rinsing process, performing so-called “spin drying”. 
     After the spin drying operation is completed, then the outer cylinder  26  is slid to the standby position to expose the rotor  24  to the outside. Next, the wafer holding member  41  of the wafer moving mechanism  40  is elevated to hold the wafers W retained in the rotor  24 . Then, the wafers Ware held by the wafer holding member  41  through other grooves different from the grooves which have been used in loading the wafers W into the rotor  24 . In this way, it is possible to prevent particles from sticking to the cleaned wafers W again. 
     Subsequently, the wafer holding member  41  with the cleaned wafers W is lowered. During this descent of the member  41 , the number of wafers W is counted by the wafer detector  99 . When the wafer holding member  41  passes through the carrier C standing ready at the carrier standby section  30 , the wafers W are retained in the wafer holding grooves in the carrier C. By the carrier conveyer mechanism  35 , the carrier C having the wafers W accommodated therein is unloaded to the stage section  4 . Further, by the carrier conveyer mechanism  12 , the carrier C is mounted on the mount table  10  of the in/out port  2 . Finally, the carrier C is further unloaded out of the cleaning apparatus  1  by means of an operator or an automatic conveyer unit. 
     It is noted that the apparatus for performing the method of the first embodiment is not limited to the shown cleaning apparatus  1 . Additionally, the present method of the invention is not limited to the cleaning process for the semiconductor wafers. Of course, the present method is applicable to cleaning process for other substrates, such as substrates for liquid crystal display (LCD) units. 
     [2nd. Embodiment] 
     Next, the second embodiment of the present invention will be described with reference to FIGS. 9 to  13 . 
     FIG. 9 shows a single wafer cleaning apparatus. This cleaning apparatus includes a spin chuck  101  for carrying the semiconductor wafer W as the substrate to be processed, a motor  102  for rotating the spin chuck  101  and a processing liquid supplying system  103  for supplying the processing liquids to the surface of the wafer W mounted on the spin chuck  101 . The system  103  includes a chemical supply unit  103 A for supplying chemical liquids, for example, resist removing liquid (i.e. resist stripper), polymer removing liquid (polymer remover), etc. and a chemical-solvent supply unit (IPA supply unit)  103 B for supplying a chemical solvent (e.g. isopropyl alcohol). The cleaning apparatus further includes a dry-gas supply unit (N 2  supply unit)  104  for supplying inert gas (e.g. N 2 -gas), dry gas (e.g. fresh air), etc. and a control unit  105  for at least controlling the timing to supply the processing liquids and remove them. 
     Hereat, the chemical solvent corresponds to a liquid that would make reaction with neither of the chemical liquid and the sequent rinsing liquid. Further, any chemical solvent will do so long as it can wash away the chemical liquids adhering to the wafer W and the chambers. 
     A cup  106  is arranged around and below the spin chuck  101  and the wafer W mounted on the spin chuck  101 . The cup  106  serves to prevent the chemical liquids and IPA from scattering out of the apparatus. The cup  106  is provided, on its bottom, with a drain port  107  and an exhaust port  108 . 
     The processing liquid supply unit  103  is equipped with a chemical nozzle  103   a  to supply (eject) the upper face of the wafer W with the processing liquid, for example, the chemical liquid. Owing to the provision of a moving mechanism  109   a , the nozzle  103   a  is movable above the wafer W horizontally and vertically. There is a chemical pipe line  103   c  which connects the nozzle  103   a  with a chemical source  103   b . The chemical pipe line  103   c  has, in order from the chemical source  103   b , a chemical pump  103   d , a filter  103   e , a temperature controller  103   f  for controlling a temperature of the chemical liquid to a predetermined temperature and an open/close valve  103   g . Between the valve  103   g  and the nozzle  103   a , a not-shown IPA source is connected with the chemical pipe line  103   c  through a not-shown switching valve. 
     The N 2  supply unit  104  is equipped with a N 2 -gas nozzle  104   a  to supply (spout) N 2 -gas to the upper surface of the wafer W. Owing to the provision of a moving mechanism  109   b , the nozzle  104   a  is also movable above the wafer W horizontally and vertically. There is a N 2 -gas pipe line  104   c  which connects the nozzle  104   a  with a N 2 -gas source  104   b . The N 2 -gas pipe line  104   c  has, in order from the source  104   b , a flow controller  104   d , a filter  104   e , an open/close valve  104   f  and a temperature controller  104   g  for adjusting a temperature of N 2 -gas to a predetermined temperature. Between the temperature controller  104   g  and the nozzle  104   a , a not-shown pure water source is connected with the pipe line  104   c  through a not-shown switching valve. 
     The control unit  105  has a central processing unit (CPU). Control signals of the control unit  105 , which will be referred as “CPU  105 ” hereinafter, are transmitted to the motor  102 , both moving mechanisms  109   a ,  109   b  (i.e. a driving system of the apparatus), the chemical supply unit  103  (i.e. the chemical pump  103   d , the temperature controller  103   f  and the open/close valve  103   g ) and also the N 2 -gas supply unit  104  (i.e. the flow controller  104   d , the open/close valve  104   f  and the temperature controller  104   g ). 
     By the control signals from the CPU  105 , the rotation of the motor  102  can be switched to any one of ranges: low-speed range (1 rpm-500 rpm), middle-speed range (100 rpm-500 rpm) and high-speed range (500 rpm-1000 rpm). 
     By the control signals from the CPU  105 , the chemical nozzle  103   a  and the N 2 -gas nozzle  104   a  can move above the wafer W horizontally and vertically. In other words, the chemical nozzle  103   a  and the N 2 -gas nozzle  104   a  can move in regard to the wafer W relatively. Furthermore, the control signals of the CPU  105  allow the wafer W to be supplied with a designated quantity of chemical liquid or N 2 -gas. Although not shown in the figure, the control signals of the CPU  105  are transmitted to the IPA supply unit and the pure-water supply unit, accomplishing to supply the wafer W with a designated quantity of IPA or pure water. 
     The cleaning method performed by the cleaning apparatus of FIG. 9 will be described with reference to FIGS. 9 to  13 . 
     First, bring the wafer W onto the spin chuck  101  by a not-shown transporting unit and further allow the chuck  101  to hold the wafer W thereon. Next, move the chemical nozzle  103   a  upward of the center of the wafer W. 
     In this state, the spin chuck  101  and the wafer W are rotated with the revolutions of 35 r.p.m. (low speed), for example and simultaneously, a predetermined quantity of polymer remover L (chemical liquid) is spouted from the chemical nozzle  103   a . This operation is continued for a predetermined period (for example, 3 seconds). Consequently, the polymer remover L invades grooves (trench) G and holes (contact holes) H on the wafer W. As shown in FIGS. 13A and 13B, the polymer remover L comes into contact with polymers P sticking to both grooves G and holes H and further makes the reaction with the polymers P thereby to dissolve the polymers P partially for their removal [see step  1 , FIGS. 10,  11 ( a ) and  12 ]. 
     However, it is noted that the rotation of the wafer W at low speed cannot make the polymer remover L invade all the grooves G and all the holes perfectly. If the polymer remover L can do, there remains a possibility that the remover L stays in the grooves G and the holes H to obstruct an invasion of new chemical liquids. From this point of view, the rotation at middle speed follows the above rotation at low speed. 
     Keeping the chemical nozzle  103   a  ejecting the designated quantity of polymer remover L, the rotating speed of the wafer W and the spin chuck  101  is accelerated to 100 rpm (middle speed) and this operation is continued for a predetermined period (for example, 3 seconds). As a result, it is possible to allow the chemical liquid to invade the grooves G and the holes H into which the chemical liquid did not invade sufficiently at step  1 . Additionally, the polymer remover L remained in the grooves G and the holes H is replaced with new polymer remover L. This flowing of the polymer remover L in the grooves G and the holes H allows the chemical processing to be effected (step  2 ). 
     Next, stop to eject the polymer remover L and rotate the spin chuck  101  and the wafer W with the revolutions of 800 rpm (high speed), thereby shaking off the used polymer remover L sticking to the wafer surface by its centrifugal force (step  3 ). 
     When the operation at step  3  is finished, start the operation at step  1  again. Thus, it is possible to replace the polymer remover L after reaction by a new polymer remover L before reaction. Note, the terms “after reaction” in the above description signifies a situation that the reactivity of the remover L is deteriorated (slow in reaction speed) as a result of sufficient progress of reaction. While, the terms “new” and “before reaction” signify one situation that the polymer remover has not been reacted yet to exhibit a high reactivity or another situation that despite of the reaction, the polymer remover has recovered a required reactivity as a result of passing through the filter etc. The operations at step  1 , step  2  and step  3  are executed, in that order, repeatedly. 
     In the above-mentioned embodiment, there are respectively established the low speed rotation of 35 rpm, the middle speed rotation of 100 rpm and the high speed rotation of 800. The respective revolutions may be changed within the range of 1 to 150 rpm for the low speed rotation, the range of 100 to 500 rpm for the middle speed rotation and the range of 500 to 3000 rpm for the high speed rotation, appropriately. Alternatively, depending on the kind of polymer remover L on use, the respective revolutions may be altered over the above ranges. Also, the periods of duration at step  1 , step  2  and step  3  may be altered appropriately. 
     Note, when the chemical-processing process is carried out at high temperatures, it is desirable to establish the temperature of the chemical liquid L somewhat larger than its optimum processing temperature, in view of accomplishing the appropriate chemical-processing process. 
     Upon confirmation of the execution of repeating the operations at steps  1 ,  2  and  3  by designated times (step  4 ), the switching valve interposing in the chemical pipe line  103   c  is activated to allow the chemical nozzle  103   a  to eject a designated quantity of solvent for the chemical liquid L, for example, IPA. 
     Thereafter, there are carried out the following steps of: 
     ejecting the IPA liquid (solvent of the chemical liquid L) through the chemical nozzle  103   a , rotating the chuck  101  and the wafer W at row speed of 35 rpm and maintaining this situation for approx. 3 seconds (step  5 ); 
     accelerating the above rotation of the chuck  101  and the wafer W up to the revolutions of 100 rpm (middle speed) while ejecting the chemical nozzle  103   a  and the IPA liquid and maintaining this situation for approx. 3 seconds (step  6 ); 
     stopping the ejection of the IPA liquid, accelerating the rotation of the chuck  101  and the wafer W up to the revolutions of 800 rpm (high speed) and maintaining this situation for approx. 3 seconds (step  7 ); and 
     repeating the operations of steps  4 ,  5  and  6 , in that order, by tens to hundreds of times. 
     In this way, the chemical components of the polymer remover sticking to the wafer surface, the grooves G and the holes H formed on the surface are completely removed. 
     Since the IPA liquid has a stickiness smaller than that of the polymer remover, the operations of step  4  and step  5  may be integrated to one step. That is, at step  4 , it will be executed to eject the IPA liquid through the chemical nozzle  103   a  while rotating the wafer W at an appropriate speed within the range from 1 to 500 rpm. (low speed to middle speed). Then, the operation of step  5  can be eliminated. 
     On confirmation of the execution of repeating the operations at steps  5 ,  6  and  7  by designated times (step  8 ), the moving mechanism  109   a  of the chemical nozzle  103   a  is activated to allow it to retreat to the standby (turnout) position. On the other hand, the N 2 -gas nozzle  104   a  also serving to supply the pure water is moved upward of the center of the wafer W. Next, supply the wafer W with the pure water (rinsing liquid) supplied from the pure water source (not shown) while rotating the wafer W thereby to remove IPA left on the wafer surface (step  9 ). 
     After completing the rinsing process in the above manner, the switching valve (not shown) interposed in the N 2 -gas pipe line  104   c  is activated. It is executed to supply the wafer surface with N 2 -gas through the N 2 -gas nozzle  104   a  thereby to remove droplets adhering to the wafer surface (step  10 ). If adjusting the temperature of N 2 -gas higher than the room temperature by the temperature controller  104   g , then it is possible to carry out the drying process effectively. Further, the combining the rotation of the wafer W with the horizontal reciprocation of the N 2 -gas nozzle  104   a  would allow the drying process to be completed promptly. After the drying process, the wafer W is unloaded out of the spin chuck  101 , completing the cleaning process. 
     We now describe test results in order to confirm the effect of the invention. 
     In the embodiment of the present invention, the wafer cleaning was carried out by repeating the operations of steps  1 ,  2  and  3  by several times. For a comparison, we further performed the wafer cleaning by repeating the operations of steps  1  and  3  by several times. The results are shown in the table below. 
     
       
         
               
               
               
             
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Example 
                 Comparative Example 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                  Conditions of 
                 Chemical (polymer 
                 Chemical (polymer 
               
               
                 Chemical processing 
                 remover) ejection: 35 
                 remover) ejection: 35 
               
               
                   
                 rpm &amp; 3 sec. (STEP 1) 
                 rpm &amp; 3 sec. (STEP 1) 
               
               
                   
                 ↓ 
                 ↓ 
               
               
                   
                 Chemical ejection: 100 
                 Chemical ejection: 800 
               
               
                   
                 rpm &amp; 3 sec. (STEP 2) 
                 rpm &amp; 3 sec. (STEP 3) 
               
               
                   
                 ↓ 
                 (Repeating steps 1, 3 
               
               
                   
                 Chemical ejection: 800 
                 for 20 times) 
               
               
                   
                 rpm &amp; 3 sec. (STEP 3) 
               
               
                   
                 (Repeating steps 1, 2, 3 
               
               
                   
                 for 10 times) 
               
             
          
           
               
                  Presence of Polymer 
                 Wafer 
                 Grooves 
                 Wafer 
                 Grooves 
               
               
                 Residuals 
                 surface 
                 Holes 
                 surface 
                 Holes 
               
               
                   
                 Not 
                 Not 
                 Not 
                 Present 
               
               
                   
                 present 
                 present 
                 present 
               
               
                   
               
             
          
         
       
     
     As shown with the table 1, it will be understood that the polymer on the wafer surface and the same in both grooves G and holes H are removed in the embodiment of the invention substantially perfectly. While, in the comparative example, the polymer in both grooves G and holes H are not removed perfectly although the polymer on the wafer surface is removed. 
     [3rd. Embodiment] 
     The second embodiment of the invention relates to the cleaning apparatus for cleaning a single wafer. Nevertheless, according to the present method, it is possible to process a plurality of wafers W at a time in the same manner as above. 
     The method of cleaning and drying the wafers will be described with reference to FIGS. 14 to  17 . 
     As shown in FIG. 14, the cleaning apparatus comprises an in/out port  200  for loading and unloading containers, for example, carriers C each having a plurality (e.g. 25 pcs.) of wafers W accommodated therein vertically, a cleaning unit  203  for applying the liquid processing and drying on the wafers W and an interface section  204  arranged between the in/out port  200  and the cleaning unit  203  to perform the delivery of the wafers W, the positional adjustment, the change of posture, etc. Note, beside the in/out port  200  and the interface section  204 , there are provided carrier-stocking units  650  each accommodating the vacant carrier C temporarily and a carrier cleaning unit  206  for cleaning the carrier C. The in/out port  200  is arranged on one side of the cleaning/drying apparatus, provided with a carrier-loading section  201  and a carrier-unloading section  202  parallel with the section  201 . 
     A carrier table  207  is arranged in the interface section  204 . Arranged between the carrier table  207  and the in/out port  200  is a carrier transporting unit  208  which transports the carrier C from the carrier loading section  201  onto the carrier table  207  or the carrier-stocking unit  205  and also which conveys the carrier C on the carrier table  207  to the carrier-unloading section  202  or the carrier-stocking unit  205 . Further, the interface section  204  is provided with a conveyer path  209 , which extends up to the cleaning unit  203 . On the conveyer path  209 , a wafer-transporting chuck  210  is arranged so as to be movable on the path  209 . The wafer transporting chuck  210  transports the unprocessed wafers W, which have been brought from the carrier C on the carrier table  207 , to the cleaning unit  203 . Further, the chuck  210  supplies the wafers W processed by the cleaning unit  203  into the carrier C. 
     The cleaning unit  203  is provided with a processing device  120  which removes resists, polymer, etc. sticking to the wafers W. As shown in FIG. 15, the processing device  220  has a rotor  221  for holding the wafers W, a motor  222  for rotating the rotor  221 , an inner cylinder  225  and an outer cylinder  226  both capable of surrounding the wafers W. Owing to the provision of a first actuator cylinder  227  and a second actuator cylinder  228 , the inner and outer cylinders  225 ,  226  can be moved to their surrounding positions to surround the rotor  221  and their standby positions apart from the surrounding positions, respectively. The inner cylinder  225  and the outer cylinder  226  define a first processing chamber  223  and a second processing chamber  224  therein, respectively. 
     The processing device  220  further includes a chemical supply unit  250  for supplying the wafers W accommodated in the inner cylinder  225  or the outer cylinder  226  with a processing fluid, for example, chemicals of resist stripper, polymer remover, etc., a solvent supply unit  260  for supplying the solvent for the chemical liquid (e.g. isopropyl alcohol: IPA), a rinse supply unit  270  for rinsing the wafers W with a rinsing liquid (e.g. pure water) and a dry-gas supply unit  280  for supplying the wafers W with dry gas, such as inert gas (e.g. N 2  gas) and fresh air. 
     Further, the processing device  220  is provided with a wafer delivery hand  229  for performing the delivery of the wafers W between the wafer transporting chuck  210  (see FIG. 14) and the rotor  221 . 
     In the so-constructed processing device  220 , all the operations of the motor  222 , respective supply parts of the units  250 ,  260 ,  270 ,  280 , the wafer delivery hand  229 , etc. are controlled by a control unit, for example, a central processing unit (CPU)  230 . 
     The rotor  221  is connected to a drive shaft  222   a  of the horizontal motor  222 , in a manner of a cantilever. Holding the wafers W having their processing surfaces in the vertical arrangement, the rotor  221  is rotatable about the horizontal axis. The rotor  221  has a first rotor disc  221   a  and a second rotor disc  221   b  opposing the first rotor disc  221   a . The first rotor disc  221   a  has a rotor shaft  221 A connected to the drive shaft  222   a  of the motor  222  through a coupling  222   b . Four immovable rods  231  bridge a gap between the first rotor disc  221   a  and the second rotor disc  221   b . The rotor  221  is further provided with a pair of movable rods  232 . The movable rods  232  are rotatable between their holding positions to hold the wafers W accommodated in the rotor  221  and their releasing positions to take the wafers W in and out of the rotor  221 . The movable rods  232  in the holding positions hold the wafers W together with the immovable rods  231 , through the wafer holding grooves formed in the rods  231 ,  232 . 
     The rotor shaft  221 A of the rotor  221  is rotatably supported by a first vertical wall  234  through bearings  233 . A labyrinth seal  235  is arranged adjacently to the bearing  233  closer to the first vertical wall  234  in order to prevent particles of the motor  222  from invading the processing chamber (see FIG.  16 ). The motor  222  is accommodated in a support cylinder  235  connected to the first vertical wall  234 . In accordance with a program stored in the CPU  30  in advance, the motor  222  rotates at predetermined revolutions. 
     As mentioned later, there is a possibility that the motor  222  is overheated due to the repetition of high-speed rotations and low-speed rotations. Therefore, the motor  222  is provided with a cooling unit  237  for restricting the motor&#39;s overheating. As shown in FIG. 15, the cooling unit  237  is formed by a circulatory cooling pipe  237   a  disposed around the motor  222  and a heat exchanger  237   c  for cooling coolant confined in the cooling pipe  237   a . The heat exchanger  237   c  includes the cooling pipe  237   a  and a coolant supply pipe  237   b  partially. Employed as the coolant is an electrically-insulating and heat-conductive liquid which does not cause a short circuit in the motor  222  even if the liquid is leaked. For example, ethylene glycol is suitable for the coolant. In order to allow of the operation based on signals from a not-shown temperature sensor, the cooling unit  237  is controlled by the CPU  230 . The cooling unit  237  does not always include the above-mentioned structure. It may be replaced by, for example, a cooling unit of air-cooled type, an electric cooling unit with Peltier elements, etc. 
     The first processing chamber  223  is defined by the first vertical wall  234 , a second vertical wall  238  opposing to the wall  234  and the inner cylinder  225 . The inner cylinder  225  is engaged with the first vertical wall  234  and the second vertical wall  238  through first and second seal members  240   a ,  240   b , respectively. By the expanding action of the first actuator cylinder  227 , the inner cylinder  225  is moved to a position to surround the rotor  221  and the wafers W, defining the first processing chamber  223 , i.e. an inner chamber. Then, the inner chamber  223  is sealed to both of the first vertical wall  234  and the second vertical wall  238  via the first sealing member  240   a  and the second sealing member  40   b , respectively (see FIGS.  15  and  16 ). 
     By the shrinking action of the first actuator cylinder  227 , the inner cylinder  225  is moved to a circumferential position of the support cylinder  236 , namely, standby (retracted) position. Then, the leading opening of the inner cylinder  225  is sealed to the first vertical wall  234  through the second sealing member  240   b . While, the base part of the inner cylinder  225  is sealed to a flange part  236   a  at the longitudinal center of the support cylinder  236  through the first sealing member  240   a . In this way, it is possible to prevent the leakage of chemical atmosphere remained in the inner cylinder  225 . 
     The second processing chamber  224  is formed by the first immovable (vertical) wall  234 , the leading end of the inner cylinder  225  moved to the standby position to engage with the wall  234  through the first sealing member  240   a , and the outer cylinder  226  engaging with the second immovable (vertical) wall  238  and the inner cylinder  225  through a third sealing member  240   c  and a fourth sealing member  240   d , respectively. 
     By the expanding action of the second actuator cylinder  228 , the outer cylinder  226  is moved to a position to surround the wafers W and the rotor  221 . At this position, the outer cylinder  226  is sealed to the second vertical wall  238  and the inner cylinder  225  through the third sealing member  240   c  and the fourth sealing member  240   d  respectively, forming the second processing chamber  224 . 
     By the shrinking action of the second actuator cylinder  228 , the outer cylinder  226  is moved to a circumferential position (standby position) of the support cylinder  236 . In this case, the fourth sealing member  240   c  is interposed between the outer cylinder  226  and the base end of the inner cylinder  225 , for sealing. Then, the interior atmosphere of the inner chamber (the first processing chamber)  223  and the interior atmosphere of the outer chamber (the second processing chamber)  224  are separated from each other in a fluid-tight manner. Therefore, there is no possibility that the atmosphere in the chamber  223  is mixed with the atmosphere in the chamber  224 , preventing the occurrence of cross-contamination due to the reaction between different processing fluids. 
     It is noted that each of the first to fourth sealing members  240   a - 240   d  is composed of a hollow gasket (packing) capable of inflating toward one side of an object to be sealed. In order to inflate the hollow gaskets, there is provided a compressor (not shown) which supplies the gaskets with compressed air. The hollow gaskets are made of synthetic rubber abounding in heat-resistance, chemical-resistance and climate-proof, such as ethylene-propylene-diene mucilage (EPDM) and Callets (product name). 
     The inner and outer cylinders  225 ,  226  are together tapered so as to extend outward against their leading ends. Consequently, when the rotor  221  is rotated in the inner cylinder  225  or the outer cylinder  226 , the inside air stream spirally flows toward the expanded side of the cylinder  225  (or  226 ), allowing the chemical liquid or the like to be forced to the expanded side for each discharge. 
     The inner and outer cylinders  225 ,  226  are slidable along three parallel guide rails (not shown) extending between the second immovable wall  238  and a sidewall  239  in the horizontal direction. The axis of the inner cylinder  225  substantially coincides with the axis of the outer cylinder  226 . Owing to the coaxial arrangement of the cylinders  225 ,  226 , it is possible to reduce the installation space for the inner and outer cylinders  225 ,  226  and also possible to miniaturize the apparatus itself. 
     The inner and outer cylinders  225 ,  226  are made of stainless steel. Additionally, the inner cylinder  225  is covered, on its outer face, with a thermal insulating layer, for example, polytetrafluoroethylene (trademark: Teflon) layer which serves to prevent the cool down of the chemical liquids and their vapor in the inner chamber  223 . 
     In the above processing fluid supply unit, the chemical (e.g. polymer stripper) supply unit  250  has a chemical nozzle  251  attached to the inner cylinder  225 , a chemical supply part  252 , a pump  254  interposed in a chemical pipe line  253  for connecting the nozzle  251  with the part  252 , a filter  255 , a temperature controller  256  and an open/close valve  257  (see FIGS. 15,  16  and  17 ). The chemical supply part  252  comprises a chemical source  258 , a chemical tank  252   a  for storing a new chemical liquid supplied from the source  258  and a circulation tank  252   b  for storing the processed chemical. Connected with both of the tanks  252   a ,  252   b  is a first drain pipe  242  which is also connected with a first drain port  241  at the lower part on the expanded side of the inner cylinder  225 . The first drain pipe  242  is connected to a circulation pipeline  290  through a switching valve (not shown). The inner cylinder  225  has a first exhaust port  243  formed at the upper part on the expanded side of the cylinder  225 . The first exhaust port  243  is connected with a first exhaust pipe  244  including an open/close valve (not shown). Temperature-control heaters  252   c  are arranged around the supply tanks  252   a ,  252   b  to maintain the chemical liquids in the tanks  252   a ,  252   b  at designated temperatures. 
     In order to supply all the wafers W of the plural number (e.g. 25 pcs.) carried in the rotor  221  with the chemical liquid uniformly, the chemical nozzle  251  is shaped in the form of a “shower” nozzle having twenty-six orifices (not shown) positioned outside the outermost wafers W and also disposed between the adjoining wafers W. Each orifice of the nozzle  251  ejects the chemical liquid in a generally fan-shaped pattern. Accordingly, when supplying the chemical liquid to the wafers W rotating together with the rotor  221  via the orifices of the nozzle  251 , it is possible to supply the wafers W of the plural number (e.g. 25 pcs.) with the chemical liquid uniformly. 
     As shown in FIG. 17, the supply unit  260  for the chemical solvent (e.g. IPA) includes the nozzle  251  also serving as the above-mentioned chemical nozzle attached to the inner cylinder  225 , a solvent supply part  261 , a pump  254 A interposed in an IPA pipeline  262  connecting the nozzle  251  with the chemical supply part  252 , a filter  255 A and an IPA supply valve  263 . Note, the above nozzle  251  will be represented by “the chemical nozzle  251 ”, hereinafter. The solvent supply part  261  is formed by a solvent (e.g. IPA) source  264 , an IPA supply tank  261   a  for storing a new IPA liquid supplied from the IPA source  264  and a circulation supply tank  261   b  for storing the IPA liquid used in the process. A circulation pipeline  290  is connected with both of the IPA supply tanks  261   a ,  261   b  through not-shown switching valves. The circulation pipeline  290  is also connected to the first drain pipe  242  associated with the first drain port  241  in the lower part of the expanded side of the inner cylinder  225 . 
     As shown in FIGS. 15,  16  and  17 , the rinse supply unit  270  for a rinsing liquid (e.g. pure water) includes a pure water nozzle  271  attached to the second vertical wall  238 , a pure water source  272 , a supply pump  274  and a pure water supply valve  275  both of which are arranged in a pure water pipe line  273  connecting the nozzle  271  with the source  272 . The pure-water nozzle  271  is positioned outside the inner cylinder  225  and also positioned inside the outer cylinder  226 . When the inner cylinder  225  retreats to the standby position and the outer cylinder  226  moves to the position to surround the rotor  221  and the wafers W to define the outer chamber  224 , then the nozzle  271  is positioned in the outer chamber  224  to supply the wafers W with the pure water. 
     The processing chamber  224  is provided, on its lower part of the expanded side, with a second drain port  245 . The second drain port  245  is connected to a second drain pipe  246  through a not-shown open/close valve. In the second drain pipe  246 , a resistivity meter  247  is interposed to detect the resistivity of pure water. On detection of the resistivity of pure water for the rinsing process, the resistivity meter  247  further outputs a signal to the CPU  230 . Since the resistivity meter  247  monitors the present rinsing situation, it is possible to accomplish the appropriate rinsing process. 
     In the upper part on the expanded side of the outer cylinder  226 , there is provided a second exhaust port  248  which is connected to a second exhaust pipe  249  having a not-shown open/close valve interposed therein. 
     As shown in FIGS. 15,  16  and  17 , the dry fluid supply unit  280  includes a dry fluid nozzle  821  fixed on the second vertical wall  238 , a dry fluid (e.g. N 2 ) source  282 , an open/close valve  284  interposed in a dry fluid pipeline  283  communicating the nozzle  281  with the source  282 , a filter  285  and a N 2 -temperature controller  286 . On the downstream side of the controller  286 , the pipeline  283  is also connected with a branch pipeline  288  through a switching valve  287 . The branch pipeline  288  is diverged from the IPA pipeline  262 . As similar to the pure water nozzle  271 , the dry fluid nozzle  281  is positioned outside the inner cylinder  225  and also inside the outer cylinder  226  both in the processing positions. With the withdrawal of the inner cylinder  225  to the standby position, when the outer cylinder  226  moves to the position to surround the rotor  21  and the wafers W to define the processing chamber  224 , the dry fluid nozzle  281  is positioned in the outer chamber  224  to supply the wafers W with the mixture of N 2 -gas and IPA in mist. After finishing drying the wafers W by the mixture of N 2 -gas and IPA, the dry fluid nozzle  281  may be dried by the supply of only N 2 -gas. In the modification, the mixture of N 2 -gas and IPA may be replaced with only N 2 -gas. 
     In chemical supply unit  250 , the IPA supply unit  260 , the pure water supply unit  270  and the dry fluid supply unit  280 , the pumps  254 ,  254 A, the temperature controller  256 , the N 2  temperature controller  286 , the open/close valve  257 , the IPA supply valve  263  and the switching valve  287  are controlled by the CPU  230  (see FIG.  15 ), which is similar to the second embodiment. 
     Note, the above-constructed processing device  220  is arranged in a processing chamber provided, on its upper part, with a filter unit (not shown), so that cleaned air is always flowing downward toward the device  220 . 
     Next, we describe the operation of the cleaning/drying apparatus in accordance. First, it is carried out to transport the carrier C to the carrier table  207  by the carrier-transporting unit  208 . In the carrier C, there are accommodated the unprocessed wafers W which have been loaded into the carrier loading section  201  of the in/out port  200 . Next, the wafer transporting chuck  210  is driven above the carrier table  207  to unload the wafers W out of the carrier C and successively transfer the delivered wafers W to the upside of the processing device  220  in the cleaning unit  203 , in other words, the upside of the rotor  221 . Then, the inner cylinder  225  and the outer cylinder  226  are withdrawn to the standby position. 
     Next, the wafer delivery hand  229  is elevated to receive the wafers W which have been transported by the wafer transporting chuck  210 . Upon receipt of the wafers W, the hand  229  is lowered to deliver the wafers W onto the immovable rods  231  on the rotor  221 . Thereafter, the hand  229  returns to the initial position. After completing to deliver the wafers W onto the rods  231 , the movable rods  232  are driven to hold the upper parts of the wafers W. In this way, the wafers W are accommodated in the rotor  221 . 
     Next, the inner cylinder  225  and the outer cylinder  226  are moved to the positions to surround the rotor  211  and the wafers W, so that the wafers W are accommodated in the processing chamber  223 . In this condition, it is carried out to supply the wafers W with the chemical liquid in the chemical-processing process. 
     This chemical-processing process is carried out in accordance with the same steps as those of the second embodiment (steps  1  to  3  of FIG.  10 ). At each step, both revolutions and duration period of the rotor  221  may be respectively equal to those of the spin chuck at each step of the second embodiment. In the steps  1  to  3  to be repeated by several times (hundreds to thousands of times), it is executed to use the chemical liquid stored in the circulation tank  252   b  at steps  1  and  2 . Then, this chemical liquid on the first use is thrown away through the first drain pipe  242 . On and after the next process, the chemical liquid stored in the circulation tank  252   b  is supplied for circulation. At steps  1  and  2  executed at the end of the chemical-processing process, a new chemical liquid supplied from the chemical source  58  into the chemical tank  252   a  is used. 
     During this chemical-processing process, the chemical liquid provided for the chemical-processing process is discharged to the first drain port  241  and further discharged into the circulating pipe line  290  of the chemical supply part  252  or the first drain pipe  242  by the switching operation of a switching valve (not shown). On the other hand, the gas generated from the chemical liquid is discharged from the first exhaust pipe  244  through the first exhaust port  243 . 
     After repeating the operations of steps  1  to  3  by several times (step  4 ), it is started to supply the wafers W with the IPA liquid for the chemical removing process. This chemical removal process is carried out in accordance with the same steps as those of the second embodiment (steps  5  to  7  of FIG.  10 ). At each step, both revolutions and duration period of the rotor  221  may be respectively equal to those of the spin chuck at each step of the second embodiment. The IPA liquid is supplied from the chemical nozzle  251  also serving as the IPA nozzle in the IPA supply unit  260 . 
     As similar to the above chemical-processing process, in steps  5  to  7  to be repeated by several times, it is executed to use the IPA liquid stored in the circulation tank  261   b  at steps  5  and  6 . Then, this IPA liquid on the first use is thrown away through the first drain pipe  242 . On and after the next process, the IPA liquid stored in the circulation tank  261   b  is supplied for circulation. At steps  5  and  6  executed at the end of the chemical removal process, a new IPA liquid supplied from the IPA source  264  into the tank  261   a  is used. 
     During this chemical removal process, the IPA liquid provided for the removal process is discharged to the first drain port  241  and further discharged into the circulating pipe line  290  of the solvent supply part  261  or the first drain pipe  242  by the switching operation of a switching valve (not shown). On the other hand, the IPA gas is discharged from the first exhaust pipe  244  through the first exhaust port  243 . 
     After completing the chemical removal process as a result of the repetition of steps  5  to  7  by several times (hundreds to thousands of times), the inner cylinder  225  is withdrawn to the standby position, so that the rotor  221  and the wafers W are surrounded by the outer cylinder  226 . In other words, the wafers W are accommodated in the processing chamber  224 . In this state, the rinsing liquid (e.g. pure water) is supplied to the rotating wafers W through the pure-water nozzle  271  of the rinse supply unit (step  9 ). When executing step  9 , it is preferable to supply CO 2  gas in the processing chamber  224 . That is, when executing step  9 , the technique mentioned in the description of the first embodiment of the present invention. The pure water provided for the rinsing process and the so-removed IPA component are together discharged from the second drain pipe  246  via the second drain port  245 . Further, the gas produced in the outer chamber  224  is discharged out of the second exhaust pipe  249  through the second exhaust port  248 . Also in the pure-water rinsing process, as similar to the chemical-processing process and the chemical removal process, there may be repeatedly carried out the following steps: (1) to supply the pure water/rotate wafers at low speed; (2) to supply the pure water/rotate wafers at middle speed; and (2) to stop the supply of pure water/rotate wafers at high speed, in that order, by several times. 
     After carrying out the rinsing process for a predetermined period, it is executed to supply the rotating wafers W with the mixed fluid of N 2 -gas from the N 2 -gas source  282  and IPA from the IPA source  264  on condition of accommodating the wafers W in the processing chamber  224 . In this way, the pure water sticking to the wafers&#39; surfaces can be removed to dry the wafers W (step  10 ). Simultaneously, the outer cylinder  226  can be dried. Additionally, if the wafers W is supplied with only N 2 -gas continuously to the above drying process using the mixture of N 2 -gas and IPA, then the drying of the wafers W and the outer chamber  24  can be progressed more effectively. 
     After completing the chemical-processing process, the chemical removal process, the rinsing process and the drying process, it is executed to withdraw the outer cylinder  226  to the standby position in the circumference of the inner cylinder  225 . While, the movable rods  232  of the rotor  221  are moved to their releasing positions (not shown). Next, the wafer delivery hand  229  is elevated to receive the wafers W held by the immovable rods  231  and thereafter, the hand  229  is moved to the upside of the processing device  220 . The wafers W brought into the upside of the processing device  220  are then received by the wafer transporting chuck  210 . The wafer transporting chuck  210  transport the wafers W to the interface section  204  and further load them into the carrier C on the carrier table  207 . Thereafter, the carrier C retaining the processed wafers W is transported to the carrier unloading section  202  by the carrier transporting unit  208 . Finally, the wafers W are discharged outside the apparatus. 
     It should be noted that the object(s) to be processed by the present processing apparatus are semiconductor wafers in common with the first embodiment to the third embodiment. Nevertheless, with no limitation to these embodiments, the invention is applicable for processing other objects, for example, glass substrates for liquid crystal display (LCD) units.