Patent Publication Number: US-2015083160-A1

Title: Ultrasonic cleaning device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application No. 2008-211977, filed Aug. 20, 2008, the contents of which are herein incorporated by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to an ultrasonic cleaning device by single-wafer spin cleaning, an immersion type ultrasonic cleaning device, and an ultrasonic cleaning device for cleaning a large substrate. 
     BACKGROUND ART 
     Single-Wafer Spin Cleaning 
       FIG. 24  is a sectional view illustrating a prior art spot-shower type ultrasonic cleaning device for single-wafer spin cleaning. This ultrasonic cleaning device is the one for cleaning an object to be cleaned  101  having a flat plane such as a semiconductor wafer. This device has a mechanism (not shown) for spinning the object to be cleaned  101  in order to clean the entire surface of the object to be cleaned  101 , an ultrasonic transducer  103  for providing ultrasonic energy to a cleaning liquid, a cleaning-liquid supply port  105  for supplying the cleaning liquid to the ultrasonic transducer  103 , a nozzle  104  for injecting a cleaning liquid  102  provided with the ultrasonic energy to the object to be cleaned  101  in a spotted manner, and a swing mechanism (not shown) for swinging the nozzle  104  (See Patent Document 1, for example). 
     As mentioned above, with the ultrasonic cleaning device shown in  FIG. 24 , since an ultrasonic irradiation region is a point (spot), there has been required a swing mechanism for swinging the nozzle  104  in order to clean the entire surface on the object to be cleaned  101 . Also, the larger a substrate to be cleaned is, the more time it takes for swinging it, and there is a problem that cleaning time of the device cannot be reduced. 
     Also, in order to reduce a distance between the nozzle  104  and the object to be cleaned  101 , the nozzle  104  needs to be installed in the vicinity on the object to be cleaned  101 , which makes workability poor. Also, since an installation space for the nozzle  104  is limited, it is difficult to install a plurality of nozzles. 
     For the cleaning liquid, in addition to deionized water and functional water in which gas (nitrogen, hydrogen, helium, ozone and the like) to improve a cleaning effect or gas (carbon dioxide) having an antistatic action are added to the deionized water, ammonia hydrogen peroxide solution with the purpose of removing particles, dilute hydrofluoric acid with an etching action, a stripper liquid for removing a resist film and the like are used. Since these cleaning liquids pass through the inside of the ultrasonic transducer  103 , a member resistant against the cleaning liquid should be selected for the housing  106 , an oscillation plate, the nozzle  104 , and a packing, which are portions to contact the liquid. Also, in order to prevent contamination from the member, cleanliness of each member should be maintained. 
       FIG. 25  is a sectional view illustrating a prior-art probe (solid rod) type ultrasonic cleaning device for single-wafer spin cleaning. This ultrasonic cleaning device is a device for cleaning the object to be cleaned  101  having a flat plane such as a semiconductor wafer. This device has a mechanism (not shown) for spinning the object to be cleaned  101  in order to clean the entire surface of the object to be cleaned  101 , a cleaning liquid supply nozzle  107  for supplying a cleaning liquid  102  to the surface of the object to be cleaned  101 , a probe (solid rod)  108  to contact the cleaning liquid  102  supplied to the surface of the object to be cleaned  101 , the ultrasonic transducer  103  for providing ultrasonic energy to the probe (solid rod)  108  through a heat transfer member  109 , and a coolant supply port  110  and a coolant discharge port  111  for supplying and discharging a coolant for cooling the heat transfer member  109  (See Patent Document 2, for example). 
     In the above-mentioned ultrasonic cleaning device shown in  FIG. 25 , since the ultrasonic irradiation region is on a line along the probe (solid rod)  108 , time required for cleaning the entire surface on the object to be cleaned  101  can be largely reduced as compared with the spot shower type cleaning device. Also, since a swing mechanism for swinging the probe (solid rod)  108  is not needed, a space required for installation of the probe (solid rod)  108  can be reduced. 
     Also, since a liquid contact portion is only the probe (solid rod)  108 , it is only necessary to select a member resistant against the cleaning liquid  102  only for the probe (solid rod)  108 . The probe (solid rod)  108  is made of an inactive non-contaminant such as quartz, and contamination from the liquid contact portion can be easily prevented. 
     Also, in order to oscillate the probe (solid rod)  108  formed from a solid material with a high density such as quartz, an acoustically large load is applied to an oscillating element and causes a large amount of heat. Thus, with such a probe (solid rod)-type ultrasonic cleaning device, energy is propagated to the probe (solid rod)  108  through the thermally conductive member  109  for cooling the ultrasonic transducer  103  and the probe (solid rod)  108 . Then, in order to efficiently cool the heat transfer member  109 , a coolant passing through the heat transfer member  109  needs to be circulated. 
     Also, if the probe (solid rod)  108  is oscillated by the drive of the ultrasonic transducer  103 , standing wave distribution is generated in the probe (solid rod)  108  as shown in  FIG. 26 . A wavelength λ of the standing wave distribution can be calculated as λ=V/F from a sonic speed V and an operating frequency F in the probe (solid rod)  108 . If the probe (solid rod) material is quartz, the sonic speed V=6000 m/s, and in the case of the operating frequency F=1 MHz, the wavelength λ=6 mm. 
     Since the sonic speed V and the operating frequency F in the probe (solid rod)  108  have a temperature characteristic, it is necessary to make temperatures of the probe (solid rod)  108  and the ultrasonic transducer  103  constant in order to maintain the standing wave distribution in the probe (solid rod)  108 . Therefore, cooling temperature control by a coolant needs to be executed. 
     Also, in order to form the standing wave distribution, it is necessary to design the probe length with integral multiple of λ/2. Since the standing wave distribution is not formed if the probe (solid rod) length is varied even slightly, predetermined oscillation amplitude is not obtained if the ultrasonic transducer  103  is driven. Therefore, it is necessary to manufacture the probe (solid rod)  108  with an accurate probe length. 
     Also, the cleaning effect can be obtained at a position of antinodes of displacement amplitude shown in  FIG. 26 , but the cleaning effect lowers at a position of nodes. An interval between nodes is λ/2=3 mm, and the cleaning effect lowers with the interval of 3 mm. 
     Also, in the ultrasonic cleaning device shown in  FIG. 25 , the length of the probe (solid rod)  108  needs to be lengthened approximately to a radius of the object to be cleaned  101 . Thus, in order to cope with an increase in diameter of the object to be cleaned  101 , the length of the probe (solid rod)  108  needs to be lengthened accordingly. For example, for a 200-mm wafer, the length of the probe (solid rod)  108  needs to be approximately 100 mm, and for a 300-mm wafer, the length of the probe (solid rod)  108  needs to be approximately 150 mm. However, the probe length that can be driven is limited, and if the probe (solid rod) reaches certain length, it can no longer be driven due to an acoustic load applied to the ultrasonic transducer. Therefore, it is difficult to cope with an increase in diameter larger than the 300-mm wafer with the ultrasonic cleaning device in  FIG. 25 . 
     Patent Document 1: Japanese Patent Laid-Open No. 2007-289807 (FIG. 1) 
     Patent Document 2: Japanese Patent No. 3493492 (FIG. 1) 
     &lt;Immersion Type Cleaning&gt; 
       FIG. 27(A)  is a sectional view of a prior-art immersion type ultrasonic cleaning device, and  FIG. 27(B)  is a sectional view obtained by cutting the ultrasonic cleaning device in a direction perpendicular to the section shown in  FIG. 27(A) . 
     This ultrasonic cleaning device has a general cleaning tank used in the immersion type cleaning of a semiconductor wafer and this cleaning tank has an indirect cleaning structure in which an inner tank  112  filled with a cleaning liquid is placed on an outer tank (not shown) in which an ultrasonic transducer  113  is installed on a bottom face. The cleaning liquid is introduced into a jet pipe  114  from a cleaning liquid inlet  114   a , and the introduced cleaning liquid is discharged from a side surface of the jet pipe  114  into the inner tank  112  as shown by an arrow and is overflowed from the upper part of the inner tank  112 . 
     A wafer as an object to be cleaned  115  installed in the inner tank  112  is supported by a carrier (transporting unit)  116  for transporting wafer. Ultrasonic energy is irradiated from the bottom face, but the ultrasonic energy hits a receiver portion  116   a  in bottom part of the carrier  116 , and there is a problem that a shaded portion in which ultrasonic energy does not reach the wafer is caused or air bubbles which adversely affect cleaning efficiency are generated. 
     Also, since the ultrasonic transducer  113  is installed on the bottom face of the cleaning tank, there is a need to provide a cleaning liquid drain port  112   a  on the side surface of the inner tank  112 . If the cleaning liquid drain port  112   a  is provided on the side surface, there is a problem that drainage of the cleaning liquid takes time or the cleaning liquid cannot fully be drained from the inner tank  112 . 
     &lt;Large Substrate Cleaning&gt; 
     A substrate size of FPD or a solar cell is getting larger, and a substrate size can reach even 2.8 m×3.5 m. In the case of a substrate with a size up to 1 m×1 m, the substrate is disposed horizontally, and the cleaning liquid provided together with ultrasonic energy is ejected like line shape shower onto this substrate by so called Ultrasonic Line Shower Cleaning Unit. In this way, the substrate is cleaned by the cleaning liquid. 
     However, as the substrate size gets larger, considering the above cleaning method for a 1.5 m×1.5 m substrate, for example, the cleaning liquid to be supplied to the substrate needs a large flow rate exceeding 100 L/min, the weight of the transducer reaches 18 kg, and as a result, manufacture and installation of the cleaning device becomes extremely difficult. Therefore, there is a problem that the cleaning device with the above cleaning method cannot process the substrate size exceeding 1 m×1 m. 
     Also, if the substrate with a size of 1.5 m×1.5 m or more is placed horizontally, the substrate is deflected by the weight of the discharged cleaning liquid, and it is foreseen that the liquid cannot be completely drained or dried. 
     DISCLOSURE OF THE INVENTION 
     As described above, with the prior-art probe (solid rod)-type ultrasonic cleaning device for single-wafer spin cleaning and the prior-art ultrasonic cleaning device for cleaning large substrates, it is difficult to cope with an increase in diameter of a cleaning surface of an object to be cleaned. Thus, the ultrasonic cleaning device is demanded which can easily cope with an increase in diameter of the cleaning surface of the object to be cleaned. 
     Also, with the prior-art immersion type ultrasonic cleaning device, the object to be cleaned  115  supported by the carrier  116  is immersed in a cleaning tank  56 , and the ultrasonic energy is irradiated from the bottom face of the cleaning tank. Thus, there is a problem that the ultrasonic energy hits the receiving portion  116   a  in bottom part of the carrier  116  and does not reach the object to be cleaned. Thus, a new ultrasonic cleaning device with which such a problem is not caused is cleaned. 
     The present invention was made in view of the above circumstances and has an purpose to solve any of the above-mentioned problems. 
     In order to solve the above problems, an ultrasonic cleaning device according to the present invention comprises: 
     an ultrasonic transducer for providing ultrasonic energy to a propagation liquid; 
     an ultrasonic propagation tube for flowing the propagation liquid provided with the ultrasonic energy by the ultrasonic transducer; 
     a holding mechanism disposed below the ultrasonic propagation tube for holding an object to be cleaned; and 
     a cleaning liquid supply mechanism for supplying a cleaning liquid to a cleaning surface of the object to be cleaned held by the holding mechanism, and 
     the ultrasonic propagation tube is disposed so that a side surface thereof may contact a liquid film of the cleaning liquid formed on the cleaning surface by supplying the cleaning liquid to the cleaning surface by the cleaning liquid supply mechanism. 
     According to the above ultrasonic cleaning device, it is possible to provide the ultrasonic energy to the cleaning liquid supplied to the cleaning surface of the object to be cleaned through the side surface of the ultrasonic propagation tube by flowing the propagation liquid provided with the ultrasonic energy by the ultrasonic transducer through the ultrasonic propagation tube. As a result, the cleaning surface of the object to be cleaned can be cleaned by the cleaning liquid and the ultrasonic energy. 
     Also, the ultrasonic cleaning device according to the present invention can further comprise: a housing for housing one end of the ultrasonic propagation tube and the ultrasonic transducer placed so as to oppose the one end; a propagation liquid supply device for supplying a propagation liquid into the housing; a dissolved gas concentration adjuster for adjusting a dissolved gas concentration of the propagation liquid; a propagation liquid recovery tank for recovering the propagation liquid discharged from the other end of the ultrasonic propagation tube; and a circulation pump for supplying the propagation liquid in the propagation liquid recovery tank into the housing again. 
     An ultrasonic cleaning device according to the present invention comprises: 
     an ultrasonic transducer for providing ultrasonic energy to a cleaning liquid; 
     an ultrasonic propagation tube for flowing the cleaning liquid provided with the ultrasonic energy by the ultrasonic transducer; 
     a holding mechanism disposed below the ultrasonic propagation tube for holding an object to be cleaned; and 
     a slit or a plurality of holes provided on a side wall of the ultrasonic propagation tube for discharging the cleaning liquid to a cleaning surface of the object to be cleaned held by the holding mechanism. 
     The above ultrasonic cleaning device flows the cleaning liquid provided with the ultrasonic energy by the ultrasonic transducer through the ultrasonic propagation tube, and discharges the cleaning liquid from the slit or the plurality of holes provided on the side wall of the ultrasonic propagation tube to the cleaning surface of the object to be cleaned. As a result, the cleaning surface of the object to be cleaned can be cleaned by the cleaning liquid and the ultrasonic energy. 
     Also, in the ultrasonic cleaning device according to the present invention, the ultrasonic propagation tube can be disposed so that the side surface thereof may contact a liquid film of the cleaning liquid formed on the cleaning surface by discharging the cleaning liquid to the cleaning surface from the slit or the plurality of holes. 
     The ultrasonic cleaning device according to the present invention comprises: 
     an ultrasonic transducer for providing ultrasonic energy to a propagation liquid; 
     an ultrasonic propagation tube for flowing the propagation liquid provided with the ultrasonic energy by the ultrasonic transducer; 
     a cleaning liquid supply pipe disposed outside the ultrasonic propagation tube so as to cover the ultrasonic propagation tube; 
     a holding mechanism disposed below the cleaning liquid supply pipe for holding an object to be cleaned; 
     an introduction port provided in the cleaning liquid supply pipe for introducing a cleaning liquid; and 
     a slit or a plurality of holes provided on a side wall of the cleaning liquid supply pipe for discharging the cleaning liquid introduced from the introduction port to a cleaning surface of the object to be cleaned held by the holding mechanism. 
     According to the above ultrasonic cleaning device, it is possible to provide the ultrasonic energy to the cleaning liquid introduced to the cleaning liquid supply pipe through the side surface of the ultrasonic propagation tube by flowing the propagation liquid provided with the ultrasonic energy by the ultrasonic transducer through the ultrasonic propagation tube. Then, the cleaning liquid provided with the ultrasonic energy is discharged from the slit or the plurality of holes to the cleaning surface of the object to be cleaned. As a result, the cleaning surface of the object to be cleaned can be cleaned by the cleaning liquid and the ultrasonic energy. 
     Also, in the ultrasonic cleaning device according to the present invention, the cleaning liquid supply pipe can be disposed so that a side surface thereof may contact a liquid film of the cleaning liquid formed on the cleaning surface by discharging the cleaning liquid from the slit or the plurality of holes to the cleaning surface. 
     Also, in the ultrasonic cleaning device according to the present invention, the ultrasonic transducer is preferably disposed so as to oppose one end of the ultrasonic propagation tube, and a single or a plurality of flange portions is preferably provided at the one end of the ultrasonic propagation tube. 
     Also, in the ultrasonic cleaning device according to the present invention, the ultrasonic transducer is preferably disposed so as to oppose one end of the ultrasonic propagation tube, and the one end of the ultrasonic propagation tube preferably has a tapered shape in which an inner diameter of the tube is getting large as getting close to the ultrasonic transducer. 
     Also, in the ultrasonic cleaning device according to the present invention, an attenuator for absorbing the ultrasonic energy can be provided at the other end of the ultrasonic propagation tube. 
     An ultrasonic cleaning device according to the present invention comprises: 
     an ultrasonic transducer for providing ultrasonic energy to a propagation liquid; 
     an ultrasonic propagation tube in a double tube structure with an inner tube and an outer tube for flowing the propagation liquid provided with the ultrasonic energy by the ultrasonic transducer, wherein the propagation liquid is introduced from one end of the inner tube and discharged from the other end of the inner tube, and the discharged propagation liquid passes through the inner surface of the outer tube and is discharged from a side surface of the outer tube; 
     a holding mechanism disposed below the ultrasonic propagation tube for holding an object to be cleaned; and 
     a cleaning liquid supply mechanism for supplying a cleaning liquid to a cleaning surface of the object to be cleaned held by the holding mechanism, and 
     the ultrasonic propagation tube is disposed so that the outer surface of the outer tube may contact a liquid film of the cleaning liquid formed on the cleaning surface by supplying the cleaning liquid to the cleaning surface by the cleaning liquid supply mechanism. 
     Also, in the ultrasonic cleaning device according to the present invention, the propagation liquid is deionized water and a dissolved gas concentration in the deionized water is preferably adjusted to 2 to 4.5 ppm. 
     An ultrasonic cleaning device for cleaning an object to be cleaned by immersing the object in a cleaning liquid within a cleaning tank according to the present invention comprises, an ultrasonic transducer for providing ultrasonic energy to the cleaning liquid; 
     an ultrasonic propagation tube for flowing the cleaning liquid provided with the ultrasonic energy by the ultrasonic transducer; and 
     a slit or a plurality of holes provided on a side wall of the ultrasonic propagation tube for discharging the cleaning liquid, and 
     the ultrasonic propagation tube is inserted into the cleaning tank, and the cleaning liquid is discharged from the slit or the plurality of holes into the cleaning tank. 
     The above ultrasonic cleaning device flows the cleaning liquid provided with the ultrasonic energy by the ultrasonic transducer through the ultrasonic propagation tube, and discharges the cleaning liquid from the slit or the plurality of holes provided on the side wall of the ultrasonic propagation tube into the cleaning tank. As a result, the object to be cleaned immersed in the cleaning liquid in the cleaning tank can be cleaned by the cleaning liquid and the ultrasonic energy. 
     Also, the ultrasonic cleaning device according to the present invention can further comprise: a housing for housing one end of the ultrasonic propagation tube and the ultrasonic transducer disposed so as to oppose the one end; 
     a cleaning liquid supply device for supplying the cleaning liquid into the housing; 
     a dissolved gas concentration adjuster for adjusting a dissolved gas concentration of the cleaning liquid; 
     a cleaning liquid recovery tank for recovering the cleaning liquid overflowed from an upper part of the cleaning device; and 
     a circulation pump for supplying the cleaning liquid in the cleaning liquid recovery tank into the housing again. 
     An ultrasonic cleaning device according to the present invention comprises: 
     an ultrasonic transducer for providing ultrasonic energy to a cleaning liquid; 
     an ultrasonic propagation tube for flowing the cleaning liquid provided with the ultrasonic energy by the ultrasonic transducer; 
     a slit or a plurality of holes provided on a side surface of the ultrasonic propagation tube for discharging the cleaning liquid; 
     a holding mechanism for holding an object to be cleaned so as to oppose the slit or the plurality of holes; and 
     a moving mechanism for relatively moving the object to be cleaned held by the holding mechanism and the ultrasonic propagation tube, and 
     the cleaning device cleans the object to be cleaned by discharging the cleaning liquid provided with the ultrasonic energy to the object to be cleaned from the slit or the plurality of holes while relatively moving the object to be cleaned and the ultrasonic propagation tube by the moving mechanism. 
     Also, in the ultrasonic cleaning device according to the present invention, the object to be cleaned can be inclined and held by the holding mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view illustrating an ultrasonic cleaning device according to an embodiment 1 of the present invention. 
         FIG. 2  is a sectional view enlarging a part of an ultrasonic propagation tube and an object to be cleaned shown in  FIG. 1 . 
         FIG. 3  is a sectional view enlarging a part of the ultrasonic propagation tube and the object to be cleaned shown in  FIG. 1 . 
         FIG. 4  is a configuration diagram illustrating a system of the ultrasonic cleaning device of the embodiment 1 of the present invention. 
         FIG. 5  is a graph illustrating a relationship between a dissolved gas concentration in deionized water and a sound pressure value. 
         FIG. 6(A)  is a sectional view illustrating an ultrasonic propagation tube of an ultrasonic cleaning device according to an embodiment 2 of the present invention,  FIG. 6(B)  is a view of the ultrasonic propagation tube shown in  FIG. 6(A)  seen from below, and  FIG. 6(C)  is a sectional view illustrating a state in which the ultrasonic propagation tube shown in  FIGS. 6(A) and 6(B)  is disposed on the object to be cleaned during cleaning. 
         FIG. 7(A)  is a sectional view illustrating a variation  1  of the ultrasonic propagation tube shown in  FIG. 6(A) ,  FIG. 7(B)  is a view of the ultrasonic propagation tube shown in  FIG. 7(A)  seen from below, and  FIG. 7(C)  is a sectional view illustrating a state in which the ultrasonic propagation tube shown in  FIGS. 7(A) and 7(B)  is disposed on the object to be cleaned during cleaning. 
         FIG. 8  is a sectional view illustrating an ultrasonic propagation tube according to a variation  2 . 
         FIG. 9  is a sectional view illustrating an ultrasonic propagation tube according to a variation  3 . 
         FIGS. 10(A) to 10(C)  are sectional views illustrating ultrasonic propagation tube according to variations  4  to  6 , respectively. 
         FIG. 11  is a sectional view illustrating an ultrasonic propagation tube according to a variation  7 . 
         FIG. 12(A)  is a plan view of arrangement of an object to be cleaned and an ultrasonic propagation tube in the ultrasonic cleaning device shown in  FIG. 1  seen from above, and  FIGS. 12(B) to 12(D)  are plan views illustrating ultrasonic propagation tubes according to variations  8  to  10 , respectively. 
         FIGS. 13(A) to 13(C)  are plan views illustrating ultrasonic propagation tubes and objects to be cleaned according to variations  11  to  13  of an embodiment 2, respectively. 
         FIG. 14(A)  is a sectional view illustrating an ultrasonic propagation tube and a cleaning liquid supply mechanism according to a variation  14  of the embodiment 1, and  FIG. 14(B)  is a sectional view illustrating a state in which the ultrasonic propagation tube and the cleaning liquid supply mechanism shown in  FIG. 14A  are disposed above the object to be cleaned.  FIG. 14(C)  is a sectional view illustrating a state in which the ultrasonic propagation tube and the cleaning liquid supply mechanism are disposed above the object to be cleaned. 
         FIG. 15  is a sectional view illustrating an ultrasonic propagation tube according to a variation  16  of the embodiment 1. 
         FIG. 16(A)  is a sectional view illustrating an immersion-type ultrasonic cleaning device according to an embodiment 3 of the present invention, and  FIG. 16(B)  is a sectional view obtained by cutting the ultrasonic cleaning device in a direction perpendicular to the section shown in  FIG. 16(A) . 
         FIG. 17  is a configuration diagram illustrating a system of the ultrasonic cleaning device of the embodiment 3 of the present invention. 
         FIG. 18  is a sectional view illustrating an immersion-type ultrasonic cleaning device according to a variation  17  of the embodiment 3. 
         FIG. 19  is a sectional view illustrating an immersion-type ultrasonic cleaning device according to a variation  18  of the embodiment 3. 
         FIG. 20  is a sectional view illustrating an immersion-type ultrasonic cleaning device according to a variation  19  of the embodiment 3. 
         FIG. 21  is a sectional view illustrating an ultrasonic cleaning device for cleaning a large substrate according to an embodiment 4 of the present invention. 
         FIG. 22  is a sectional view illustrating an ultrasonic cleaning device according to a variation  20  of the embodiment 4. 
         FIG. 23  is a sectional view illustrating an ultrasonic cleaning device according to a variation  21  of the embodiment 4. 
         FIG. 24  is a sectional view illustrating a prior-art spot-shower type ultrasonic cleaning device for single-wafer spin cleaning. 
         FIG. 25  is a sectional view illustrating a prior-art probe (solid rod) type ultrasonic cleaning device for single-wafer spin cleaning. 
         FIG. 26  is a diagram illustrating a standing wave distribution propagating in the probe (solid rod) shown in  FIG. 25 . 
         FIG. 27(A)  is a sectional view illustrating a prior-art immersion type ultrasonic cleaning device, and  FIG. 27(B)  is a sectional view obtained by cutting the ultrasonic cleaning device in a direction perpendicular to the section shown in  FIG. 27(A) . 
         FIG. 28  is a schematic diagram illustrating a method for measuring a sound pressure of this embodiment and a sound pressure of a prior art, respectively. 
         FIG. 29  is a photo showing an entire device when the sound pressure of this embodiment and the sound pressure of the prior art are measured, respectively. 
         FIG. 30  is a photo showing a tube portion of the device when the sound pressure of this embodiment and the sound pressure of the prior art are measured, respectively. 
         FIG. 31  is a graph illustrating measurement results of the sound pressure of this embodiment and the sound pressure of the prior art measured, respectively. 
         FIG. 32  is a graph for showing oscillation propagation comparison simulation of a prior art solid rod and a tube of this invention and illustrates oscillation distribution of ultrasonic propagation tube of this invention. 
         FIG. 33  is a graph for showing oscillation propagation comparison simulation of a prior art solid rod and a tube of this invention and illustrates oscillation distribution of a prior art solid rod. 
         FIG. 34  is a diagram illustrating conditions of the simulation of the ultrasonic propagation tube of this invention. 
         FIG. 35  is a diagram illustrating conditions of the simulation of the prior art solid rod. 
     
    
    
     EXPLANATION OF REFERENCE NUMERALS 
     
         
         
           
               11  case (housing) 
               12 ,  37 ,  40 ,  42  to  53 ,  55 ,  63  ultrasonic propagation tube 
               12   a ,  44   a  to  46   a  rear end portion 
               12   b ,  47   b  front end portion 
               13  ultrasonic transducer 
               13   a  disk-shaped oscillation plate 
               14  propagation liquid supply port 
               15  propagation liquid 
               16  stage 
               17  rotation support portion 
               18  cleaning liquid supply nozzle 
               19 ,  57  cleaning liquid 
               20  propagation liquid supply device 
               21  object to be cleaned 
               22  dissolved gas concentration adjuster 
               23  temperature adjuster 
               24  flow meter 
               25  joint 
               26  drain tube 
               27  propagation liquid recovery tank 
               28  circulation pump 
               29  filter 
               30  oscillator 
               32  sound pressure sensor 
               33  sound pressure meter 
               34  CPU 
               35  cleaning liquid recovery tank 
               36  drain 
               38  round hole 
               39  cleaning liquid 
               39   a  liquid film 
               41  slit (groove) 
               42   a ,  42   b  tube wall 
               44   b ,  45   b  flange portion 
               46   b  tapered shape 
               47   a  attenuator 
               54  cleaning liquid supply pipe 
               54   a  introduction port 
               54   b  round hole 
               55   a  inner tube 
               55   b  outer tube 
               55   a   1  distal end (front end portion) 
               55   b   1  distal end (front end portion) 
               55   b   2  discharge port 
               56  cleaning tank 
               56   a  drain port 
               58  carrier (transporting unit) 
               58   a  receiver portion 
               59  semiconductor wafer 
               60  cleaning liquid inlet 
               61  cleaning liquid recovery tank 
               62  cleaning liquid supply device 
               64  large substrate 
               65  transporting shaft 
               66  transporting roller 
           
         
       
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will be described below in detail using the attached drawings. However, it is easily understood by those skilled in the art that the present invention is not limited to the following description and its modes and details can be modified in various ways without departing from the gist and scope of the present invention. Therefore, the present invention should not be interpreted with limitation to the described contents of the embodiments shown below. 
     Single-Wafer Spin Cleaning 
     Embodiment 1 
       FIG. 1  is a sectional view illustrating an ultrasonic cleaning device according to an embodiment 1 of the present invention.  FIGS. 2 and 3  are sectional views enlarging a part of an ultrasonic propagation tube  12  and an object to be cleaned  21  shown in  FIG. 1 . 
     The ultrasonic cleaning device shown in  FIG. 1  has a case (housing)  11 , and the ultrasonic propagation tube  12  is mounted at a distal end portion of the case (housing)  11 . A material of this ultrasonic propagation tube  12  is an inactive non-contaminant such as quartz, which can easily prevent contamination from a liquid contact portion. Since a solution containing hydrofluoric acid has an action to etch quartz, if a solution containing hydrofluoric acid is to be used as a cleaning liquid, sapphire, silicon carbide or high purity aluminum (Al 2 O 3 ) may be used or quartz coated with a substance resistant against the hydrofluoric acid solution such as silicon carbide, high purity aluminum (Al 2 O 3 ), PFA of fluorine resin and the like may be used as a material of the ultrasonic propagation tube  12 . Since quartz, sapphire and silicon carbide are vulnerable to impact and expensive, stainless steel such as SUS316L may be used. If a problem of chemical resistance or elution of metal contamination is worried in manufacture of the ultrasonic propagation tube of stainless steel, electrolytic polishing or surface modification processing can be applied to the ultrasonic propagation tube. 
     Within the case (housing)  11 , a disk-shaped ultrasonic transducer  13  is placed opposing a rear end portion  12   a  of the ultrasonic propagation tube  12 . This ultrasonic transducer  13  has a disk-shaped oscillation plate  13   a  in an integral configuration, and the surface of the oscillation plate  13   a  opposes the rear end portion  12   a  of the ultrasonic propagation tube  12  as an oscillating surface of the ultrasonic transducer  13 . Also, in a side surface of the case  11 , a propagation liquid supply port  14  for supplying a propagation liquid  15  for propagating an ultrasonic wave is formed, and deionized water at a room temperature is preferably used, for example, for the propagation liquid  15 . 
     Also, the ultrasonic cleaning device has a stage  16  for holding an object to be cleaned  21  having a flat plane such as a semiconductor wafer, and a rotation support portion  17  is mounted below the stage  16 . On this rotation support portion  17 , a rotating mechanism (not shown) for rotating the rotation support portion  17  is mounted. 
     Above the stage  16 , a cleaning liquid supply nozzle  18  for supplying a cleaning liquid  19  is disposed, and the cleaning liquid  19  is supplied to the surface of the object to be cleaned  21  by this cleaning liquid supply nozzle  18 . The ultrasonic propagation tube  12  contacts the cleaning liquid  19  supplied to the surface of the object to be cleaned  21 . That is, the ultrasonic propagation tube  12  is disposed at a height in contact with a liquid film (cleaning liquid)  19  on the surface of the object to be cleaned  21  and is extended from one outer periphery to the other outer periphery of the object to be cleaned  21 . A front end portion  12   b  of the ultrasonic propagation tube  12  is disposed outside the other outer periphery so that the propagation liquid  15  is discharged from the front end portion  12   b.    
     Next, an operation of the ultrasonic cleaning device shown in  FIG. 1  will be described. 
     The cleaning device holds object to be cleaned  21  on the stage  16 , and supplies the cleaning liquid  19  to the surface of the object to be cleaned  21  from the cleaning liquid supply nozzle  18 , while rotating the object to be cleaned  21  by rotating the stage  16 . Also, the cleaning device supplies the propagation liquid to the ultrasonic transducer  13  inside the case (housing)  11  from the propagation liquid supply port  14 , flows the propagation liquid  15  provided with an ultrasonic wave by the ultrasonic transducer  13  from the rear end portion  12   a  to the front end portion  12   b  of the ultrasonic propagation tube  12 , and discharges the propagation liquid  15  from the front end portion  12   b , which is an open end. 
     A wavelength λ of the ultrasonic wave propagating in deionized water, which is the propagation liquid  15 , flowing inside the ultrasonic propagation tube  12  as shown in  FIG. 2  is acquired by λ=V/F from a sonic speed V=1500 m/s in the deionized water and an operating frequency F=1 MHz, and by calculating this, the wavelength λ=1.5 mm is acquired. This ultrasonic wave repeats reflection and propagates inside the ultrasonic propagation tube  12  but a part thereof transmits through the ultrasonic propagation tube  12 , propagates in the cleaning liquid  19 , and reaches the object to be cleaned  21 . As a result, the surface of the object to be cleaned  21  is cleaned by the ultrasonic wave and the cleaning liquid  19 . 
     In the above embodiment 1, the propagation liquid  15  makes ultrasonic oscillation propagate within it and also works as a refrigerant for removing heat from the ultrasonic transducer  13 . Thus, cooling is performed efficiently, and since heat is not generated even if large energy is given to the ultrasonic transducer  13 , the sonic speed V and the operating frequency F in the propagation liquid  15  having a temperature characteristic can be easily maintained constant. 
     Also, since the distal end (front end portion  12   b ) of the ultrasonic propagation tube  12  is an open end, as shown in  FIG. 3 , the ultrasonic wave propagating in the propagation liquid  15  becomes a continuous wave, and standing wave distribution is not caused. Thus, since there is no node in an oscillation amplitude as in the probe (solid rod)-type ultrasonic cleaning device in  FIG. 25 , uniform cleaning effects can be realized. Also, since there is no need to accurately determine the length of the ultrasonic propagation tube, manufacture of the device is easier as compared with the probe (solid rod)-type ultrasonic cleaning device. 
     Also, even if the ultrasonic propagation tube  12  is made longer in order to cope with an increase in diameter of the object to be cleaned  21 , although the length of the propagation liquid  15  also becomes longer, there is little change in an acoustic load applied to the transducer of the deionized water, which is the propagation liquid  15 . Thus, there is no limitation on the length of the ultrasonic propagation tube which can be driven, and a larger diameter of the object to be cleaned  21  can be easily handled. 
     Also, in the embodiment 1, since the ultrasonic irradiation region is on the line along the ultrasonic propagation tube  12 , time required for cleaning the entire surface on the object to be cleaned  21  can be drastically reduced as compared with a point (spot) of the ultrasonic irradiation region of the ultrasonic cleaning device shown in  FIG. 24 . Also, there are merits that a mechanism for oscillating the ultrasonic propagation tube  12  is not needed, and the ultrasonic propagation tube  12  and the case  11  can be installed without requiring a large space. 
     Also, a liquid contact portion is only the ultrasonic propagation tube  12 , and it is only necessary to select a member resistant against the cleaning liquid  19  only for the ultrasonic propagation tube  12 . Also, by maintaining cleanliness of only the ultrasonic propagation tube  12 , contamination from the member can be easily prevented. 
     Also, in the ultrasonic cleaning device of the embodiment 1, ultrasonic oscillation is given to the propagation liquid  15  from the ultrasonic transducer  13 , deionized water at a room temperature is used for the propagation liquid  15 , and a density of the deionized water is approximately 1000 kg/m 3 , which is smaller than a density of quartz at 2200 kg/m 3  forming the probe (solid rod)  108  shown in  FIG. 25 . Thus, an acoustic load applied on the ultrasonic transducer  13  can be made smaller than that of the device shown in  FIG. 25 , and heat generation of the ultrasonic transducer  13  can be reduced. 
     Also, there is an obvious difference as follows between the prior-art probe (solid rod) type ultrasonic cleaning device shown in  FIG. 25  and the ultrasonic cleaning device of this embodiment. 
     The ultrasonic cleaning device shown in  FIG. 25  is a device that oscillates the probe (solid rod)  108 , which is a solid such as quartz and has a high density, by the ultrasonic transducer  103  through a heat conductive member  109  to make the probe (solid rod) itself work as a transducer having standing wave distribution, provides ultrasonic energy to the liquid film (cleaning liquid)  102  in contact with the probe (solid rod)  108  to make the liquid film  102  work as an energy propagation path, and supplies the ultrasonic energy to the object to be cleaned. 
     On the other hand, the ultrasonic cleaning device of this embodiment is a device in which the ultrasonic oscillation energy from the ultrasonic transducer  13  propagates to the propagation liquid  15  in the ultrasonic propagation tube  12 , and the ultrasonic wave in the propagation liquid  15  propagates by repeating reflection in the ultrasonic propagation tube  12 , while apart of ultrasonic wave transmits through the ultrasonic propagation tube  12 , propagates to the cleaning liquid  19  and reaches the object to be cleaned  21 . Therefore, the propagation liquid  15  filled in the ultrasonic propagation tube  12  is a propagation path for the ultrasonic energy from the ultrasonic transducer  13  but is not a transducer. The ultrasonic propagation tube  12  has a role to hold the propagation liquid  15  and to form the propagation path but is not a transducer. 
     The ultrasonic cleaning device of this embodiment does not provide megasonic energy to a cleaning fluid by the probe (solid rod)  108  as shown in  FIG. 25 . This will be described below in detail. 
     In the ultrasonic cleaning device of this embodiment, the propagation liquid  15  provided with an ultrasonic wave flows from the rear end portion  12   a  toward the front end portion  12   b  of the ultrasonic propagation tube  12 , and a part of the ultrasonic wave propagating in the propagation liquid  15  transmits through the ultrasonic propagation tube  12  and propagates into the cleaning liquid  19 . Therefore, from the functional viewpoint, the probe for providing the ultrasonic wave to the cleaning liquid may correspond to the propagation liquid  15  flowing through the ultrasonic propagation tube  12 . 
     However, the probe (solid rod)  108  shown in  FIG. 25  is a probe made of a solid and not a probe made of a liquid. 
     Also, the ultrasonic propagation tube  12  of this embodiment does not correspond to the probe (solid rod)  108  shown in  FIG. 25 . This will be described below in detail. 
     The ultrasonic propagation tube  12  does not contact the oscillation plate  13   a  as shown in  FIG. 1 , and the propagation liquid  15  exists between the surface of the oscillation plate  13   a  and the rear end portion  12   a  of the ultrasonic propagation tube  12 . Therefore, the ultrasonic wave from the oscillation plate  13   a  is not directly transmitted to the ultrasonic propagation tube  12 . Since the ultrasonic propagation tube  12  does not provide the ultrasonic wave to the cleaning liquid as above, the ultrasonic propagation tube  12  does not correspond to the probe (solid rod) shown in  FIG. 25 . 
     Next, a sound pressure when apart of the ultrasonic wave propagating in the propagation liquid  15  flowing through the ultrasonic propagation tube  12  transmits through the ultrasonic propagation tube  12  and propagates into the cleaning liquid  19  (hereinafter referred to as “sound pressure of this embodiment”) and a sound pressure when the megasonic energy is provided to the cleaning fluid by the probe (solid rod)  108  shown in  FIG. 25  (hereinafter referred to as “sound pressure of the prior art”) will be described. 
     The sound pressure of this embodiment and the sound pressure of the prior art are totally different from each other from the following reasons. 
     In this embodiment, since the distal end (front end portion  12   b ) of the ultrasonic propagation tube  12  is made open for flowing the propagation liquid  15 , the ultrasonic wave propagating in the propagation liquid  15  becomes a continuous wave having traveling wave distribution, and standing wave distribution is not caused as shown in  FIG. 3 . On the other hand, in the probe (solid rod)  108  shown in  FIG. 25 , since this probe (solid rod)  108  is solid, standing wave distribution is caused by a reflective wave from the distal end (free end) of the probe (solid rod). 
     In order to prove the above contents, an experiment was conducted for measuring the sound pressure of this embodiment and the sound pressure of the prior art, respectively. The measuring method of the sound pressure is shown in  FIG. 28 , and photos at the measurement are shown in  FIGS. 29 and 30  and the measurement results in  FIG. 31 . 
     The measurement conditions are as follows: 
     water temperature: room temperature (approximately 20° C.) 
     water quality: deaerated water (DO 1 ppm or less) 
     flow rate of this invention: 1.0 L/min 
     tank water supply rate: 5 to 7 L/min 
     tank capacity: 250×250×400 mm 
     input power; 30 W 
     oscillation frequency: 950 kHz 
     number of measurement times: 2 (average value) 
     tube diameter: φ6 mm (inner diameter φ4) 
     As shown in  FIG. 31 , the sound pressure of this embodiment is confirmed as a continuous wave traveling with a substantially constant amplitude (see  102 ), while with the sound pressure of the prior art, it is confirmed that the amplitude has an attenuating tendency but an amplitude value thereof is larger than that of the sound pressure of this embodiment and represents standing wave distribution (see  101 ). That is, if a difference between the minimum amplitude and the maximum amplitude is small, it represents traveling wave distribution, while the difference between the minimum amplitude and the maximum amplitude is large, it represents standing wave distribution. With regard to the sound pressure of this embodiment, the difference between the minimum amplitude and the maximum amplitude is small, and it represents traveling wave distribution. Also, the amplitude is substantially constant, and no attenuating tendency is found. With regard to the sound pressure of the prior art, the difference between the minimum amplitude and the maximum amplitude is large, and it represents standing wave distribution. Also, the amplitude shows an attenuating tendency. 
     (attenuation) 
     probe (solid rod): attenuating from 30 dB to 20 dB
         -&gt;load is large for quartz horn       

     tube: constant approximately at 20 dB
         -&gt;load is small for deionized water tube       

     (Distribution) 
     probe (solid rod): distribution is caused
         -&gt;propagating with standing wave (wavelength: 6 mm)       

     tube: distribution is not caused
         -&gt;propagating with traveling wave       

     Moreover, in order to prove the above contents, simulation was conducted to compare oscillation propagation of the probe (solid rod) shown in  FIG. 25  and the oscillation propagation of the propagation liquid  15  flowing through the ultrasonic propagation tube  12  of this embodiment, and simulation results are shown in  FIGS. 32 and 33  and simulation conditions in  FIGS. 34 and 35 . 
     As shown in  FIGS. 33 , in the case of the probe (solid rod) shown in  FIG. 25 , no large difference is found in the oscillation amplitude between the center portion (see  105 ) and the outer periphery portion (see  106 ) of the probe (solid rod), and it shows that the oscillation is propagated in the entire probe (solid rod). On the other hand, as shown in  FIG. 32 , in the case of this embodiment, it is known that the oscillation is propagated mainly by a medium (water) (see  103 ). Therefore, the both are fundamentally different in terms of a system of oscillation propagation. In this way, the sound pressure of this embodiment is totally different from that of the prior art. 
     With regard to the cleaning liquid  19 , various cleaning liquids can be used depending on the object to be cleaned  21 , and other than deionized water and functional water in which a gas for improving a cleaning effect (nitrogen, hydrogen, helium, ozone and the like) or a gas having an antistatic action (carbon dioxide) is added to deionized water, ammonia hydrogen peroxide solution with the purpose of removing particles, dilute hydrofluoric acid with an etching action, potassium chloride (KOH), a stripper liquid for removing a resist film and the like can be used. 
     Next, an example in which the ultrasonic cleaning device shown in  FIG. 1  is systemized will be described referring to  FIG. 4 .  FIG. 4  is a configuration diagram illustrating a system of the ultrasonic cleaning device of the embodiment 1, and the same reference numerals are given to the same portions as those in  FIG. 1 . 
     As shown in  FIG. 4 , the propagation liquid supplied from the propagation liquid supply device  20  is supplied to the ultrasonic propagation tube  12  through a dissolved gas concentration adjuster  22 , a temperature adjuster  23 , and a flow meter  24 . Here, it is possible to set characteristics (dissolved gas concentration, temperature, and flow rate) of the propagation liquid  15  to conditions suitable for the cleaning. 
     At a distal end (front end portion  12   b ) of the ultrasonic propagation tube  12 , a joint  25  and a drain tube  26  are mounted. As a result, the propagation liquid  15  is fed to a propagation liquid recovery tank  27 . The propagation liquid  15  recovered in the propagation liquid recovery tank  27  can be circulated by a circulation pump  28 . The propagation liquid  15  having passed through the circulation pump  28  is regenerated through a filter  29 . The regenerated propagation liquid  15  is supplied to the ultrasonic propagation tube  12  through the dissolved gas concentration adjuster  22 , the temperature adjuster  23 , and the flowmeter  24 , which is the same path as that described above. 
     Electrical power is supplied to the ultrasonic transducer by the oscillator  30 , an ultrasonic wave is provided to the propagation liquid by the ultrasonic transducer, and ultrasonic energy is propagated to the propagation liquid  15  filled in the ultrasonic propagation tube  12 . 
     The cleaning liquid supplied from the cleaning liquid supply device is supplied onto the ultrasonic propagation tube  12  or onto the object to be cleaned  21 , and a liquid film (cleaning liquid)  19  in contact with the ultrasonic propagation tube  12  is formed on the object to be cleaned  21 . At this time, the object to be cleaned  21  is rotated together with the stage  16 . The ultrasonic energy transmitted through the ultrasonic propagation tube  12  propagates in the cleaning liquid  19  and reaches the object to be cleaned  21 . As a result, the surface of the object to be cleaned  21  is cleaned by the ultrasonic wave and the cleaning liquid  19 . The cleaning liquid  19  after cleaning is recovered in the cleaning liquid recovery tank  35  and discharged to a drain  36 . 
     A sound pressure sensor  32  is mounted on a side surface of the ultrasonic propagation tube  12 , and the ultrasonic energy transmitted through the ultrasonic propagation tube  12  is detected by this sound pressure sensor  32 . Data of the detected ultrasonic energy is sent to a sound pressure meter  33  through a CPU  34 , converted to a voltage value at the sound pressure meter  33  and sent to the CPU  34 . An output voltage value of the oscillator  30  has been also sent to the CPU  34  at the same time, and if the sound pressure value (voltage value of the ultrasonic energy) is lower than the output voltage value, it can be determined that the ultrasonic energy has been lowered. The characteristics of the propagation liquid  15  (dissolved gas concentration, temperature, and flow rate) are also sent as data to the CPU  34  from the dissolved gas concentration adjuster  22 , the temperature adjuster  23 , and the flow meter  24 , respectively. The CPU  34  can make a control to start oscillation after confirming that the data has reached a predetermined value. As a result, empty operation particularly caused by a lowered flow rate can be prevented. 
     Depending on the type of the cleaning liquid  19 , the temperature may be raised to approximately 70° C., and in that case, in order to maintain cleaning quality, the temperature is preferably kept constant. Thus, by raising the temperature of the propagation liquid  15  to approximately 70° C. by the temperature adjuster  23 , temperature drop of the cleaning liquid  15  in contact with the ultrasonic propagation tube  12  can be prevented. Temperature rise of the ultrasonic transducer during operation is approximately a liquid temperature+20° C. With the liquid temperature of 70° C., the temperature of the ultrasonic transducer becomes 90° C. Because an allowable temperature of the ultrasonic transducer is approximately 120° C., there is no problem in use. 
       FIG. 5  is a graph illustrating a relationship between a dissolved gas concentration in deionized water and a sound pressure value (voltage value of ultrasonic energy). Although the gas concentration dissolved in deionized water as propagation liquid is usually approximately 7 to 8 ppm for dissolved oxygen concentration, a high cleaning effect can be obtained as shown in  FIG. 5 , by adjusting the dissolved oxygen concentration to 2 to 4.5 ppm (more preferably 2 to 3 ppm) at which a high sound pressure value can be obtained. Therefore, with the ultrasonic cleaning device shown in  FIG. 4 , the dissolved gas concentration adjuster  22  is preferably controlled by the CPU  34  so that the dissolved oxygen concentration in the deionized water as the propagation liquid is adjusted to 2 to 3 ppm. 
     Embodiment 2 
       FIG. 6(A)  is a sectional view illustrating an ultrasonic propagation tube of an ultrasonic cleaning device according to an embodiment 2 of the present invention,  FIG. 6(B)  is a view of the ultrasonic propagation tube shown in  FIG. 6(A)  seen from below, and  FIG. 6(C)  is a sectional view illustrating a state in which the ultrasonic propagation tube shown in  FIGS. 6(A) and 6(B)  is arranged on the object to be cleaned  21 . 
     In the ultrasonic cleaning device of the embodiment 1 shown in  FIG. 1 , the propagation liquid  15  and the cleaning liquid  19  are configured to be separated from each other, but in the ultrasonic cleaning device of the embodiment 2, the cleaning liquid is used as the propagation liquid, and the propagation liquid and the cleaning liquid are configured to be made common. That is, in the ultrasonic cleaning device according to the embodiment 2, the ultrasonic propagation tube  12  of the ultrasonic cleaning device shown in  FIG. 1  is replaced by an ultrasonic propagation tube  37  shown in  FIGS. 6(A) to 6(C) , and the cleaning liquid supply nozzle  18  is eliminated. 
     As shown in  FIGS. 6A and 6B , round holes  38  aligned in a single row are provided on a side surface of the ultrasonic propagation tube  37 , and as shown in  FIG. 6C , the ultrasonic propagation tube  37  is disposed in proximity above the object to be cleaned  21  in the ultrasonic cleaning device. In the ultrasonic propagation tube  37 , a cleaning liquid  39  as a propagation liquid provided with ultrasonic energy is made to flow, and the cleaning liquid  39  is discharged onto the object to be cleaned  21  through the round holes  38 . That is, the ultrasonic energy is discharged together with the cleaning liquid  39  onto the object to be cleaned  21  through the round holes  38 . As a result, a liquid film  39   a  formed from the cleaning liquid  39  in contact with the ultrasonic propagation tube  37  is formed on the object to be cleaned  21 , and the ultrasonic energy cleans the object while being supplied to the object to be cleaned  21  through the liquid film  39   a.    
     In the embodiment 2, the effect similar to that of the embodiment 1 can be also obtained. 
     Also, since the cleaning liquid is used as the propagation liquid, it is not necessary to provide a device for supplying the cleaning liquid separately from the propagation liquid supply device. 
     (Variation) 
       FIG. 7(A)  is a sectional view illustrating a variation  1  of an ultrasonic propagation tube shown in  FIG. 6(A) ,  FIG. 7(B)  is a view of the ultrasonic propagation tube shown in  FIG. 7(A)  seen from below, and  FIG. 7(C)  is a sectional view illustrating a state where the ultrasonic propagation tube shown in  FIGS. 7(A) and 7(B)  are disposed above the object to be cleaned  21  for cleaning. 
     As shown in  FIGS. 7(A) and 7(B) , a slit (groove)  41  formed on a single line is provided in a side surface of an ultrasonic propagation tube  40 , and as shown in  FIG. 7(C) , the ultrasonic propagation tube  40  is disposed above the object to be cleaned  21  in the ultrasonic cleaning device, which is farther away from each other as compared with  FIG. 6C . In the ultrasonic propagation tube  40 , the cleaning liquid  39  as a propagation liquid provided with ultrasonic energy is made to flow, and the cleaning liquid  39  is discharged onto the object to be cleaned  21  through the slit  41 . As a result, the ultrasonic energy is supplied to the object to be cleaned  21  through the cleaning liquid  39  and the object is cleaned. At this time, since the ultrasonic propagation tube  40  and the object to be cleaned  21  are arranged farther away from each other as compared with  FIG. 6C , the ultrasonic propagation tube  40  does not contact a liquid film formed from the cleaning liquid  39  on the object to be cleaned  21 . 
     In the variation  1  also, the effect similar to that of the embodiment 2 can be obtained. 
     Also, the ultrasonic propagation tube  37  shown in  FIGS. 6(A) and 6(B)  may be disposed so as not to contact the liquid film as shown in  FIG. 7(C)  or the ultrasonic propagation tube  40  shown in  FIGS. 7A and 7B  may be disposed so as to contact the liquid film as shown in  FIG. 6(C) . 
       FIG. 8  is a sectional view illustrating an ultrasonic propagation tube according to a variation  2 . The ultrasonic propagation tubes in each of the embodiments 1, 2, and the variation  1  may be changed to an ultrasonic propagation tube  42  shown in  FIG. 8  and put into practice. This ultrasonic propagation tube  42  has a tube wall  42   a  having a thickness transmitting an ultrasonic wave and a tube wall  42   b  having a thickness not transmitting the ultrasonic wave. As a result, in the ultrasonic propagation tube  42 , a region transmitting the ultrasonic wave and a region not transmitting the one are provided. 
       FIG. 9  is a sectional view illustrating an ultrasonic propagation tube according to a variation  3 . The ultrasonic propagation tubes in each of the embodiments 1, 2, and the variation  1  may be changed to an ultrasonic propagation tube  43  shown in  FIG. 9  and put into practice. This ultrasonic propagation tube  43  has a tube  43   a  constructed by a material having a density transmitting an ultrasonic wave and a covering tube  43   b  covering a part of the tube  43   a , and the covering tube  43   b  is constructed by a material having a density not transmitting the ultrasonic wave. 
       FIGS. 10(A) to 10(C)  are sectional views illustrating ultrasonic propagation tubes according to variations  4  to  6 , respectively. The ultrasonic propagation tubes in the embodiments 1, 2, and the variation  1  may be changed to ultrasonic propagation tubes  44  to  46  shown in  FIGS. 10(A) to 10(C) , respectively, and put into practice. In the ultrasonic propagation tubes  44  to  46 , each of the distal ends (rear end portions  44   a  to  46   a ) has a shape that causes ultrasonic energy to efficiently propagate to the ultrasonic transducer  13  having a diameter larger than an outer diameter of the ultrasonic propagation tube. 
     At the rear end portion  44   a  of the ultrasonic propagation tube  44  shown in  FIG. 10(A) , a flange portion  44   b  is provided so as to oppose the ultrasonic transducer  13 . By means of this flange portion  44   b , the ultrasonic wave is multiply-reflected so that ultrasonic intensity can be increased. 
     At the rear end portion  45   a  of the ultrasonic propagation tube  45  shown in  FIG. 10(B) , a plurality of flange portions  45   b  is provided so as to oppose the ultrasonic transducer  13 . By means of these flange portions  45   b , the ultrasonic wave is multiply-reflected so as to increase the ultrasonic intensity, while a rectification effect of the propagation liquid can be provided. 
     The rear end portion  46   a  of the ultrasonic propagation tube  46  shown in  FIG. 10(C)  has a tapered shape  46   b  in which a tube inner diameter is getting larger as getting closer to the ultrasonic transducer  13 . By means of this tapered shape  46   b , the ultrasonic wave can be converged so as to increase the ultrasonic intensity. 
       FIG. 11  is a sectional view illustrating an ultrasonic propagation tube according to a variation  7 . The ultrasonic propagation tube in each of the embodiments 1, 2, and the variation  1  may be changed to an ultrasonic propagation tube  47  shown in  FIG. 11  and put into practice. At a distal end (front end portion  47   b ) of this ultrasonic propagation tube  47 , an attenuator  47   a  for absorbing ultrasonic energy is provided. The ultrasonic wave having reached the attenuator  47   a  is not reflected but absorbed by the attenuator  47   a , and thereby the ultrasonic wave to be propagated becomes a continuous wave, and standing wave distribution is not caused. Thus, since a node of an oscillation amplitude as considered in the probe (solid rod)-type ultrasonic cleaning device in  FIG. 25  is not present, uniformity of the cleaning effect can be realized. 
       FIG. 12(A)  is a plan view of arrangement of the object to be cleaned and the ultrasonic propagation tube in the ultrasonic cleaning device shown in  FIG. 1  when seen from above, and  FIGS. 12(B) to 12(D)  are plan views illustrating ultrasonic propagation tubes according to variations  8  to  10 , respectively. 
     As shown in  FIG. 12(A) , the ultrasonic propagation tube  12  according to the embodiment 1 has a linearly extending shape. On the other hand, as shown in  FIGS. 12(B) to 12(D) , the ultrasonic propagation tubes  48  to  50  according to the variations  8  to  10  have shapes bent at the center of the object to be cleaned  21 . In detail, the ultrasonic propagation tube  48  shown in  FIG. 12(B)  is bent at a sharp angle, the ultrasonic propagation tube  49  shown in  FIG. 12(C)  is bent at a right angle, and the ultrasonic propagation tube  50  shown in  FIG. 12(D)  is bent so as to be folded back. 
     According to the variations  8  to  10 , since the ultrasonic propagation tube can be manufactured by bending it to various shapes, design freedom in a device whose installation space is limited can be improved. 
       FIGS. 13(A) to 13(C)  are plan views illustrating ultrasonic propagation tubes and objects to be cleaned according to variations  11  to  13  of the embodiment 2. Ultrasonic propagation tubes  51  to  53  according to the variations  11  to  13  are applied to ultrasonic cleaning devices using the propagation liquid and the cleaning liquid in common. 
     As shown in  FIGS. 13(A) to 13(C) , by disposing outlets of the ultrasonic propagation tubes  51  to  53  for flowing the cleaning liquid as the propagation liquid above the objects to be cleaned  21 , the cleaning liquid as the propagation liquid can be supplied onto the objects to be cleaned  21 . Also, similarly to the embodiment 2, a cleaning liquid supply device from outside is not needed. Also, the ultrasonic propagation tube can be manufactured with its distal end bent in an arbitrary direction, and a discharging direction of the cleaning liquid can be determined according to the device. 
       FIG. 14(A)  is a sectional view illustrating an ultrasonic propagation tube and a cleaning liquid supply mechanism according to a variation  14  of the embodiment 1, and  FIG. 14(B)  is a sectional view illustrating a state in which the ultrasonic propagation tube and the cleaning liquid supply mechanism shown in  FIG. 14(A)  are arranged above the object to be cleaned. 
     This is a double tube structure in which a cleaning liquid supply pipe  54  is disposed outside the ultrasonic propagation tube  12  similar to the embodiment 1 shown in  FIG. 1 . An introduction port  54   a  for introducing the cleaning liquid  19  is provided at an upper part of the cleaning liquid supply pipe  54 , and a round hole  54   b  or a slit (groove) is provided at a lower part of the cleaning liquid supply pipe  54 . The cleaning liquid  19  is introduced into the cleaning liquid supply pipe  54  from the introduction port  54   a , and the cleaning liquid  19  in the cleaning liquid supply pipe  54  is discharged onto the object to be cleaned  21  through the round hole  54   b  or the slit. Since the round hole  54   b  or the slit is disposed in proximity of the object to be cleaned  21 , a liquid film  19   a  formed from the cleaning liquid  19  in contact with the cleaning liquid supply pipe  54  is formed on the object to be cleaned  21 , and the object is cleaned while the ultrasonic energy is supplied to the object to be cleaned  21  through the liquid film  19   a.    
       FIG. 14(C)  is a sectional view illustrating a state in which an ultrasonic propagation tube and a cleaning liquid supply mechanism according to a variation  15  of the embodiment 1 are arranged above the object to be cleaned, and the same reference numerals are given to the same portions as those in  FIG. 14(B) , and only different portions will be described. 
     As shown in  FIG. 14(C) , the round hole  54   b  or the slit of the cleaning liquid supply pipe  54  is disposed with a distance far away from the object to be cleaned  21 . Even with this arrangement, the cleaning liquid  19  to which the ultrasonic energy propagated can be supplied to the object to be cleaned. 
       FIG. 15  is a sectional view illustrating an ultrasonic propagation tube according to a variation  16  of the embodiment 1. An ultrasonic propagation tube  55  has a double-tube structure constituted by an inner tube  55   a  and an outer tube  55   b . A distal end (front end portion)  55   a   1  of the inner tube  55   a  is open, and a distal end (front end portion)  55   b   1  of the outer tube  55   b  is closed. On a side wall of the outer tube  55   b , a discharge port  55   b   2  for discharging—the propagation liquid is provided. As a result, the propagation liquid  15  discharged from the distal end  55   a   1  of the inner tube  55   a  can be recovered by the outer tube  55   b , and the recovered propagation liquid  15  can be discharged from the discharge port  55   b   2  of the outer tube  55   b . That is, the ultrasonic energy discharged together with the propagation liquid  15  from the distal end  55   a   1  of the inner tube  55   a  can be circulated on an inner face of the outer tube  55   b , which is an irradiation region, and the ultrasonic energy can be effectively used. Also, the outlet of the propagation liquid  15  can be provided at an arbitrary location of the outer tube  55   b  and can be designed according to an installation space of the device. 
     In the ultrasonic cleaning device according to the variation  16 , the ultrasonic propagation tube  12  of the ultrasonic cleaning device shown in  FIG. 1  may be changed to the ultrasonic propagation tube  55  shown in  FIG. 15  and put into practice. Also, in the ultrasonic cleaning device according to the variation  16 , the ultrasonic propagation tube  12  of the ultrasonic cleaning device shown in  FIG. 4  may be changed to the ultrasonic propagation tube  55  shown in  FIG. 15  and put into practice. In this case, the joint  25  shown in  FIG. 4  is mounted at the discharge port  55   b  shown in  FIG. 15 . 
     In the variation  16  also, the effect similar to that of the embodiment 2 can be obtained. 
     Immersion-Type Cleaning 
     Embodiment 3 
       FIG. 16(A)  is a sectional view illustrating an immersion-type ultrasonic cleaning device according to an embodiment 3 of the present invention, and  FIG. 16(B)  is a sectional view obtained by cutting the ultrasonic cleaning device in a direction perpendicular to the section shown in  FIG. 16(A) . 
     This ultrasonic cleaning device has a cleaning tank  56  filled with a cleaning liquid  57  and is a device in which the cleaning tank  56  is filled with the cleaning liquid  57  and a carrier (transporting unit)  58  holding a plurality of semiconductor wafers  59  as objects to be cleaned is immersed for cleaning in the cleaning liquid  57  in the cleaning tank  56 . 
     In the cleaning tank  56 , the two ultrasonic propagation tubes  37  shown in  FIGS. 6(A) and 6(B)  are inserted and mounted. The ultrasonic propagation tube  40  shown in  FIGS. 7(A) and 7(B)  may be used in this embodiment. At a distal end (front end portion) of the ultrasonic propagation tube  37 , the attenuator  47   a  for absorbing ultrasonic energy similar to that in  FIG. 11  is mounted, and the attenuator  47   a  exerts the effect similar to that of the variation  7  shown in  FIG. 11 . 
     At a base end (rear end portion) of the ultrasonic propagation tube  37 , an ultrasonic transducer (not shown) is disposed in an opposing manner, and the ultrasonic transducer is disposed in the housing  11 . In this housing  11 , a cleaning liquid inlet  60  is provided. 
     The cleaning liquid also acting as a propagation liquid is provided with ultrasonic energy by the ultrasonic transducer, the cleaning liquid is discharged into the cleaning tank  56  through the round hole in the ultrasonic propagation tube  37  and overflowed from an upper part of the cleaning tank  56 , and the overflowed cleaning liquid is recovered by a cleaning liquid recovery tank  61 . 
     According to the embodiment 3, since the ultrasonic propagation tube  37  is disposed so that the ultrasonic energy can be supplied to the semiconductor wafer  59 , avoiding a receiver portion  58   a  of the carrier  58 , a portion shaded by the receiver portion or generation of air bubbles such as in a prior-art immersion-type ultrasonic cleaning device can be suppressed. 
     Also, since there is no need to provide an oscillation plate as in the prior-art immersion-type ultrasonic cleaning device, a drain port  56   a  can be provided on a bottom face of the cleaning tank  56 , and time for discharge can be reduced and the cleaning liquid can be fully discharged. Also, without newly preparing a cleaning tank, by adding the ultrasonic propagation tube  37  to the cleaning tank of the prior-art immersion-type ultrasonic cleaning device, the ultrasonic cleaning device of this embodiment can be realized. 
     Next, an example in which the ultrasonic cleaning device shown in  FIGS. 16(A) and 16(B)  is systematized will be described referring to  FIG. 17 .  FIG. 17  is a configuration diagram illustrating a system of the ultrasonic cleaning device of the embodiment 3, and the same reference numerals are given to the same portions to those in  FIGS. 16(A) and 16(B) . 
     As shown in  FIG. 17 , a cleaning liquid supply device  62  for supplying a cleaning liquid also acting as a propagation liquid is supplied to the ultrasonic propagation tube  37  through the dissolved gas concentration adjuster  22 , the temperature adjuster  23 , the flow meter  24 , and the cleaning liquid inlet  60 . Here, it is possible to set characteristics (dissolved gas concentration, temperature, flow rate) of the cleaning liquid to conditions suitable for the cleaning. 
     The cleaning liquid provided with ultrasonic energy is discharged from a hole provided on a side surface of the ultrasonic propagation tube  37 , and the cleaning liquid is supplied together with the ultrasonic energy into the cleaning tank  56 . The cleaning liquid  57  in the cleaning tank  56  is overflowed from the upper part of the cleaning tank  56 , and the overflowed cleaning liquid is recovered by a cleaning liquid recovery tank  61 . The recovered cleaning liquid is circulated by the circulation pump  28  and passed through a filter  29  for regeneration. The regenerated cleaning liquid is supplied to the ultrasonic propagation tube  37  through the dissolved gas concentration adjuster  22 , the temperature adjuster  23 , and the flow meter  24 , which is the same path as that described above. 
     Electrical power is supplied to the ultrasonic transducer by the oscillator  30 , an ultrasonic wave is provided to the cleaning liquid by the ultrasonic transducer, and ultrasonic energy propagates to the cleaning liquid filled in the ultrasonic propagation tube  37 . 
     The sound pressure sensor  32  is mounted on a side surface of the ultrasonic propagation tube  37 , and the ultrasonic energy transmitted through the ultrasonic propagation tube  37  is detected by this sound pressure sensor  32 . Data of the detected ultrasonic energy is sent to the sound pressure meter  33  through the CPU  34 , converted to a voltage value at the sound pressure meter  33  and sent to the CPU  34 . An output voltage value of the oscillator  30  is also sent to the CPU  34  at the same time, and if the sound pressure value (voltage value of the ultrasonic energy) is lower than the output voltage value, it can be determined that the ultrasonic energy has been lowered. The characteristics of the cleaning liquid  57  (dissolved gas concentration, temperature, flow rate) are also sent as data to the CPU  34  from the dissolved gas concentration adjuster  22 , the temperature adjuster  23 , and the flow meter  24 , respectively. The CPU  34  can control the oscillation to start after confirming that the data has reached a predetermined value. In addition, empty operation caused by a lowered flow rate can be prevented. 
     If the cleaning liquid  57  is to be replaced, the cleaning liquid in the cleaning tank  56  is discharged from the drain port  56   a  and drained to the drain  36 . 
     Depending on the type of the cleaning liquid  57 , the temperature is raised to approximately 70° C., and in that case, in order to maintain cleaning quality, the temperature is preferably kept constant. For this purpose, the temperature of the propagation liquid  57  can be kept at approximately 70° C. by the temperature adjuster  23 . Temperature rise of the ultrasonic transducer during operation is approximately a liquid temperature+20° C. With the liquid temperature of 70° C., the temperature of the ultrasonic transducer becomes 90° C., but an allowable temperature of the ultrasonic transducer is approximately 120° C., and there is no problem in use. 
     (Variation) 
       FIG. 18  is a sectional view illustrating an immersion-type ultrasonic cleaning device according to a variation  17  of the embodiment 3, and the same reference numerals are given to the same portions as those in  FIG. 16(A) , and only different portions will be described. 
     An ultrasonic propagation tube  63  is manufactured in a shape bent in the middle, and an inlet and an outlet for a cleaning liquid acting as a propagation liquid can be provided outside a cleaning tank. That is, in the ultrasonic cleaning device shown in  FIGS. 16(A) and 16(B) , a mounting hole of the ultrasonic propagation tube  37  is provided in a wall face of the cleaning tank  56 , and the ultrasonic propagation tube  37  is inserted into the cleaning tank  56  through this mounting hole. On the other hand, in the variation  17 , there is no need to provide a mounting hole for the ultrasonic propagation tube in the wall face of the cleaning tank  56 . Therefore, with this variation, the ultrasonic propagation tube can be easily added to a cleaning tank without a mounting hole. 
     In the above variation  17  also, the effect similar to that of the embodiment 3 can be obtained. 
       FIG. 19  is a sectional view illustrating an immersion-type ultrasonic cleaning device according to a variation  18  of the embodiment 3, and the same reference numerals are given to the same portions as those in  FIG. 16(B) , and only different portions will be described. 
     By arranging a large number of the ultrasonic propagation tubes  37  in the cleaning tank  56 , a cleaning area can be widened. That is, in the ultrasonic cleaning device shown in  FIGS. 16(A) and 16(B) , the two ultrasonic propagation tubes  37  are disposed in the cleaning tank  56 . In the variation  18 , six ultrasonic propagation tubes  37  are disposed in the cleaning tank  56 . 
     In the above variation  18  also, the effect similar to that of the embodiment 3 can be obtained. 
       FIG. 20  is a sectional view illustrating an immersion-type ultrasonic cleaning device according to a variation  19  of the embodiment 3, and the same reference numerals are given to the same portions as those in  FIG. 16(B) , and only different portions will be described. 
     In the ultrasonic cleaning device of the variation  19 , the ultrasonic propagation tube  37  is added to the prior-art immersion-type cleaning tank  112  shown in  FIG. 27B  and used with the oscillation plate  113 . In this case, by arranging four ultrasonic propagation tubes  37  in the vicinity of the receiver  58   a  so that the cleaning liquid provided with the ultrasonic energy is discharged in the vicinity of the receiver  58   a , there is an effect that air bubbles generated in the vicinity of the receiver  58   a  are removed. 
     Large Substrate Cleaning 
     Embodiment 4 
       FIG. 21  is a sectional view illustrating an ultrasonic cleaning device for cleaning a large substrate according to an embodiment 4 of the present invention. 
     In the ultrasonic cleaning device shown in  FIG. 21 , the ultrasonic propagation tube  37  shown in  FIGS. 6(A) and 6(B)  are used. In this embodiment, the ultrasonic propagation tube  40  shown in  FIGS. 7(A) and 7(B)  maybe also used. At the distal end (front end portion) of the ultrasonic propagation tube  37 , the attenuator  47   a  for absorbing ultrasonic energy similar to that in  FIG. 11  is mounted, and the attenuator  47   a  exerts the effect similar to that of the variation  7  shown in  FIG. 11 . 
     At a base end (rear end portion) of the ultrasonic propagation tube  37 , an ultrasonic transducer (not shown) is disposed in an opposing manner, and the ultrasonic transducer is disposed in the housing  11 . In this housing  11 , the cleaning liquid inlet  60  is provided. 
     The cleaning liquid also acting as a propagation liquid is provided with ultrasonic energy by the ultrasonic transducer, and the cleaning liquid is discharged onto the surface of a large substrate  64 , which is an object to be cleaned, through a round hole in the ultrasonic propagation tube  37 . 
     The large substrate  64  is held by a holding mechanism so that a surface thereof opposes aside surface of the ultrasonic propagation tube  37 . This holding mechanism has a plurality of transporting shafts  65  arranged with a predetermined interval, a plurality of transporting rollers  66  mounted on the transporting shaft  65 , and a rotation mechanism (not shown) for rotating the transporting shafts  65 . 
     By rotating the transporting roller  66  through rotation of the transporting shaft  65  using the rotation mechanism, the cleaning liquid provided with the ultrasonic energy is discharged from the plurality of round holes onto the surface (face to be cleaned) of the large substrate  64  as shown by an arrow while the large substrate  64  is moved relatively to the ultrasonic propagation tube  37 . In this way, the surface of the large substrate  64  can be cleaned. 
     If the above ultrasonic cleaning device is applied to the large substrate  64  having a size of 1.5 m×1.5 m, a flow rate of the cleaning liquid discharged from the ultrasonic propagation tube  37  can be reduced to approximately 20 L/min, which is ⅕ of that of the prior-art ultrasonic cleaning device, and the weight of the ultrasonic transducer can be reduced to approximately 6 kg, which is ⅓ of that of the prior-art ultrasonic cleaning device. Therefore, manufacture and installation of the ultrasonic cleaning device becomes extremely easier as compared with the prior-art device. 
     (Variation) 
       FIG. 22  is a sectional view illustrating an ultrasonic propagation device according to a variation  20  of the embodiment 4, and the same reference numerals are given to the same portions as those in  FIG. 21 , and only different portions will be described. 
     Ultrasonic transducers (not shown) are mounted at both ends of the ultrasonic propagation tube  37 . As a result, ultrasonic energy provided to the cleaning liquid can be increased. 
     In the above variation  20  also, the effect similar to that of the embodiment 4 can be obtained. 
       FIG. 23  is a sectional view illustrating an ultrasonic propagation device according to a variation  21  of the embodiment 4, and the same reference numerals are given to the same portions as those in  FIG. 21 , and only different portions will be described. 
     If the large substrate  64  with a size of 1.5 m×1.5 m or more is horizontally placed as in the embodiment 4, for example, there is a fear that the large substrate is deflected by the weight of the discharged cleaning liquid, and the liquid cannot be completely drained or dried. 
     Then, since the ultrasonic propagation tube  37  is light-weighted and can be easily installed even if it is a vertical type, vertical transporting of the large substrate  64  is used. That is, the large substrate  64  is inclined and held by the holding mechanism for transporting. As a result, the cleaning liquid on the large substrate  64  can be easily drained after cleaning and can be easily dried. 
     In the above variation  21  also, the effect similar to that of the embodiment 4 can be obtained. 
     The present invention is not limited to the above embodiments and variations but is capable of being put into practice with various changes within a scope not departing from the gist of the present invention. For example, it is possible to put the present invention into practice by combining the embodiments and variations as appropriate.