JP5245701B2 - Ultrasonic irradiation device, cleaning device and cleaning method - Google Patents

Description

  The present invention relates to an ultrasonic irradiation apparatus, a cleaning apparatus, and a cleaning method. For example, in a single wafer type spin cleaning system in which a liquid cleaning liquid is poured onto the surface of a rotating wafer to perform cleaning, the wafer is not damaged. It is related with the structure for removing efficiently the contaminant adhering to the surface of this.

  In recent years, in the manufacture of semiconductor devices, the wafer size has been increased, and accordingly, single wafer spin cleaning is becoming mainstream in the wafer cleaning process. This single-wafer spin cleaning is easier to perform a uniform cleaning process on the wafer surface than the dip cleaning performed using a large cleaning tank, and contaminants removed from the wafer surface are less likely to adhere to the wafer surface. There are many advantages such as the ability to suppress the amount of cleaning liquid and rinsing pure water used, and the start-up of the cleaning device in a short time.

  In such spin cleaning, a spin cleaning apparatus for cleaning a wafer by ultrasonic cleaning is generally used (see, for example, Patent Document 1 or Patent Document 2). In this case, the cleaning liquid is sprayed from the ultrasonic nozzle onto the surface of the wafer, and at the same time, an ultrasonic wave is generated by oscillating the vibrator inside the ultrasonic nozzle, and the ultrasonic wave is generated using the cleaning liquid sprayed from the ultrasonic nozzle as a medium. It propagates to the surface and cleans the wafer surface using ultrasonic energy.

  FIG. 11 is an explanatory diagram of a conventional spin cleaning method using an ultrasonic nozzle, in which a cleaning liquid 73 is ejected from the ultrasonic nozzle 72 toward the wafer 71. When an ultrasonic transducer (not shown) built in the ultrasonic nozzle 72 is operated, the generated ultrasonic wave propagates to the wafer surface using the cleaning liquid 73 as a medium. In a state where the wafer 71 is rotated, the ultrasonic nozzle 72 so that an irradiation point 74, which is a point where the cleaning liquid 73 ejected from the ultrasonic nozzle 72 hits the wafer surface, reciprocates between the rotation center and the outer periphery of the wafer. , The irradiation point 74 passes through the entire surface of the wafer, and the entire surface of the wafer 71 is cleaned.

  By the way, in recent years, along with the progress of miniaturization of wiring rules of semiconductor elements, a process in which a wafer on which a fine structure (pattern) that is very fragile is formed on the surface must be cleaned during the manufacturing process. Is increasing. For example, reactive dry etching is used to reduce the width of an interlayer insulating layer made of porous silica (porous silica) in which fine pores called pores are uniformly distributed for the purpose of lowering the relative dielectric constant. It is assumed that a fine pattern having a thickness of less than 100 nm is formed. When ultrasonic cleaning is performed on such a wafer using an ultrasonic nozzle, the pattern on the wafer surface may be destroyed due to damage given by the ultrasonic waves.

  In order to avoid such a problem, it is necessary to reduce the energy of the ultrasonic wave irradiated per unit area of the wafer surface according to the structural strength of the pattern formed on the wafer surface. In the cleaning apparatus using the ultrasonic nozzle shown in FIG. 11 described above, the ultrasonic vibrator built in the ultrasonic nozzle is driven so that damage to the structure on the wafer surface by the ultrasonic wave can be reduced. In many cases, a mechanism capable of adjusting a drive output is provided in an ultrasonic oscillator for generating the ultrasonic oscillator. As a result, if it is within a certain range, the drive output can be set small. If the drive output is still too large, it is necessary to modify (remodel) the electronic circuit of the ultrasonic oscillator so that it can be driven with a smaller output.

  However, even if the drive output can be reduced by modifying the electronic circuit of the ultrasonic oscillator, the ultrasonic vibrator built in the ultrasonic nozzle has a specific vibration condition determined by the shape and structure, and there is a drive output. If the lower limit is not reached, stable vibration will not be established. In the case of a high frequency, if the drive output of the ultrasonic transducer falls below a certain level, the attenuation of the ultrasonic wave in the cleaning liquid sprayed from the ultrasonic nozzle becomes abrupt and the ultrasonic wave is generated on the wafer. Does not reach the surface. As described above, when the ultrasonic nozzle is used, it is difficult to irradiate the wafer surface with the ultrasonic wave by operating the vibrator with a very small driving output.

  Therefore, for such a problem, an ultrasonic irradiation method using a vibrating body has been proposed for the purpose of reducing ultrasonic damage to the wafer as much as possible, and will be described with reference to FIG. For example, see Patent Document 3).

  FIG. 12 is an explanatory view of a conventional spin cleaning method for cleaning a wafer by ultrasonic cleaning, FIG. 12 (a) is a perspective view of the overall configuration, and FIG. 12 (b) is an enlarged plan view of the main part. is there. As shown in the figure, an ultrasonic transducer 76 is installed on one of the flat surfaces of a vibrating body 75 that is a wedge-shaped member. The vibrating body 75 is held so that another flat surface of the wedge-shaped vibrating body 75 faces the surface to be cleaned of the wafer 71 in parallel with a small distance. The cleaning liquid 73 is supplied from the nozzle 77 so that the space formed between the vibrating body 75 and the wafer 71 is completely filled with the cleaning liquid 73.

  When the ultrasonic transducer 76 is driven in this state, the generated ultrasonic wave propagates inside the vibrating body 75, is transmitted from the entire surface facing the wafer 71 to the cleaning liquid 73, and propagates in the cleaning liquid 73. As a result, it reaches the surface of the wafer 71 to be cleaned. The manner of vibration of the surface facing the wafer 71 is determined by the manner of vibration of the ultrasonic vibrator 76 and the shape and material of the vibrator 75. These are predicted by simulation in advance, and the design of the vibrator 75 is designed according to the purpose. It is reflected in. FIG. 12 shows an example in which a wedge-shaped ceramic vibrating body is employed, but there are various materials, shapes, and structures of the vibrating body (see, for example, Patent Document 4).

  In the method using such a vibrating body, the entire surface of the vibrating body vibrates due to the ultrasonic vibration generated by the ultrasonic vibrator, so that the vibration energy is dispersed and irradiated per unit area of the surface to be cleaned. The energy of the ultrasonic wave is significantly smaller than that of the ultrasonic nozzle, and the effect of reducing the ultrasonic damage to the wafer surface can be obtained.

  In addition, the ultrasonic wave generated on the surface of the vibrating body reaches the surface to be cleaned only by propagating through the cleaning liquid film having a thickness of several millimeters, in many cases only about 1 mm or less in many cases. Even if the ultrasonic vibration energy on the surface of the vibrating body is very small, it is possible to irradiate the surface to be cleaned without significant attenuation and to ensure the effect of cleaning. .

In this way, by adopting a spin cleaning method using a vibrating body, ultrasonic damage to the wafer surface can be reduced, and destruction of fine structures (patterns) formed on the wafer surface can be prevented. I was able to do that.
JP 2006-122822 A JP 2008-021672 A JP 2003-181394 A JP 2003-031540 A

  However, the spin cleaning method using the vibrator described above has a problem that the removal efficiency of the foreign matter adhering to the wafer surface is low compared to the spin cleaning method using the ultrasonic nozzle as shown in FIG. is there. Specifically, when cleaning a wafer having foreign matter adhered to the surface under the same conditions, the spin cleaning method using a vibrating body can obtain the same foreign matter removal rate as the spin cleaning method using an ultrasonic nozzle. The problem is that it takes several times longer.

  Also, unlike the batch type processing method that can process a large number of wafers at the same time, it takes a long time to process each wafer in the single wafer type processing method, which reduces the processing capacity of the entire process. Will cause very serious problems.

  The inventors investigated the cause of the low efficiency of removing foreign substances in the cleaning method using the vibrator. There are two major steps in the process of cleaning and removing foreign matter from the surface of a wafer. The first is a step of floating foreign matter adhering to the wafer surface in the cleaning liquid by the energy of the ultrasonic wave applied to the wafer surface. The greater the energy of the irradiated ultrasonic wave, the greater the effect of raising the foreign matter in the cleaning liquid and the higher the removal efficiency. However, on the other hand, the damage given to the wafer surface is increased, and the structure formed on the wafer surface is destroyed.

  The second is a step of removing foreign substances floating in the cleaning liquid together with the cleaning liquid and removing them from the wafer surface. When the flow of the cleaning liquid on the wafer surface stagnate, the foreign matter that has floated in the cleaning liquid due to the action of ultrasonic waves tends to adhere to the wafer surface again, leading to a reduction in removal efficiency. Such re-adhesion remarkably occurs particularly when the potentials (zeta potentials) in the cleaning liquid of the materials of the wafer surface and the foreign material are different from each other and attractive force is generated.

  As a result of intensive studies by the inventors, in the spin cleaning method using a vibrating body, the energy of ultrasonic waves irradiated per unit area is certainly much smaller than that in a spin cleaning method using an ultrasonic nozzle. However, it has been found that the size is sufficient to allow foreign matter to float in the cleaning liquid from the wafer surface.

  In addition, the cleaning efficiency of the spin cleaning method using the vibrating body is reduced because of the poor flow of the cleaning liquid in the minute space sandwiched between the vibrating body and the wafer surface, and the foreign matter generated on the wafer surface. It was determined that reattachment was the cause.

  Accordingly, an object of the present invention is to reduce damage using a vibrating body and prevent reattachment of foreign matters to the wafer surface.

From one aspect of the present invention, a hollow rotating body having a cylindrical outer peripheral side surface, means for supporting the hollow rotating body and rotating the hollow rotating body around a central axis of the hollow rotating body, , e Bei and means for generating an ultrasonic vibration to the outer peripheral side surface of the hollow rotary body, means for producing ultrasonic vibration to the outer peripheral side surface of said hollow rotating body, the hollow portion of the hollow rotary body A columnar vibrator inserted into the hollow rotator with a minute gap, and a liquid that satisfies the minute gap between the vibrator and the hollow rotator and propagates ultrasonic waves satisfactorily. There is provided an ultrasonic irradiation apparatus comprising: means for generating ultrasonic vibration on an outer peripheral side surface of the vibrating body .

  Further, from another aspect of the present invention, means for horizontally supporting the wafer and rotating the wafer in that state, the above-described ultrasonic irradiation apparatus, and supporting the ultrasonic irradiation apparatus, and Means for reciprocating the ultrasonic irradiation device in parallel with the wafer surface while the outer peripheral side surface of the hollow rotating body is separated from the surface of the wafer by a minute and constant interval, and supplying a cleaning liquid to the wafer surface A cleaning device is provided.

  Moreover, from another viewpoint of this invention, the cleaning method characterized by cleaning a wafer using the above-mentioned cleaning apparatus is provided.

  According to the disclosed ultrasonic irradiation apparatus, cleaning apparatus, and cleaning method, while taking advantage of the cleaning method using a vibrating body that reduces damage to the wafer surface, foreign matter that has floated in the cleaning liquid by the action of ultrasonic waves It is possible to reduce the reattachment to the wafer surface and greatly increase the removal efficiency of foreign matters.

  Here, an embodiment of the present invention will be described with reference to FIG. The present invention is based on such problems of the spin cleaning method using a vibrating body, while taking advantage of the small damage to the wafer surface, and at the same time, the cleaning liquid in the space sandwiched between the vibrating body and the wafer surface. The flow can be improved and the occurrence of redeposition can be greatly reduced.

  FIG. 1 is an explanatory diagram of the principle configuration of the spin cleaning method of the present invention, and is a configuration explanatory diagram along a cross section of a hollow rotating body including a vibrating body. As shown in FIG. 1, an ultrasonic irradiation apparatus 10 used for spin cleaning includes a columnar vibrating body 11, a hollow rotating body 12 including the vibrating body 11 through a minute gap, and the vibrating body 11 and the hollow rotating body 12. And an ultrasonic medium liquid 13 filled in a minute gap. Note that an ultrasonic transducer (not shown) is connected to one end of the vibrating body 11.

  The center axis of the vibrating body 11 and the center axis of the hollow rotating body 12 are arranged to coincide with each other, and the hollow rotating body 12 is also made of a material that propagates ultrasonic waves satisfactorily, for example, silicon, like the vibrating body 11. It is made of synthetic quartz that does not contain impurities and has excellent chemical resistance. The hollow rotating body 12 is supported so that it can freely rotate around the vibrating body 11. The vibrating body 11 serves as a rotation axis of the hollow rotating body 12, and the vibrating body 11 itself does not rotate.

  The diameters of the vibrating body 11 and the inner side surface of the hollow rotating body 12 are set so that a minute gap is provided. As a result, a cylindrical space is formed between the two. This space is filled with a liquid having the property of favorably propagating ultrasonic waves, that is, the ultrasonic medium liquid 13. As the ultrasonic medium liquid 13, the cleaning liquid 22 used for spin cleaning is used as it is so that the ultrasonic medium liquid 13 does not affect the cleaning effect even if it flows out to the surface of the wafer during the cleaning. Is preferred.

  A cleaning liquid 22 is supplied to the surface of the wafer 21 to form a film of the cleaning liquid 22. The vibrating body 11 is supported so that the central axis of the vibrating body 11 is parallel to the surface of the wafer 21, and the outer peripheral side surface of the hollow rotating body 12 is in contact with the film of the cleaning liquid 22 formed on the surface of the wafer 21. The distance between the wafer 21 and the vibrating body 11 is set.

  When an ultrasonic transducer connected to one end of the vibrating body 11 is operated, ultrasonic vibration propagates to the entire vibrating body 11. The ultrasonic wave propagates from the outer peripheral side surface of the vibrating body 11 to the ultrasonic medium liquid 13 on the outer side and reaches the inner side surface of the outer hollow rotating body 12. The ultrasonic wave 14 reaching the inner side surface of the hollow rotator 12 propagates through the hollow rotator 12 and reaches the outer peripheral side surface of the hollow rotator 12.

  The ultrasonic wave 14 reaching the outer peripheral side surface of the hollow rotator 12 is irradiated from the outer peripheral side surface of the hollow rotator 12 into the film of the cleaning liquid 22 formed on the surface of the wafer 21, reaches the surface of the wafer 21, and the wafer 21. The foreign substance is removed from the surface of the liquid and floats into the cleaning liquid 22. When the ultrasonic wave 14 reaches the outer peripheral side surface of the hollow rotator 12, the ultrasonic energy is dispersed, and the ultrasonic energy irradiated per unit area of the surface of the wafer 21 is greatly reduced. As in the case of a spin cleaning method using a vibrating body, an effect of reducing ultrasonic damage given to the surface of the wafer 21 can be obtained.

  Further, since the ultrasonic wave applied to the cleaning liquid 22 from the outer peripheral side surface of the hollow rotating body 12 reaches the surface of the wafer 21 only by propagating through the film of the cleaning liquid 22 having a thickness of about 1 mm or less, the conventional ultrasonic wave is reached. As in the case of spin cleaning using a vibrating body, even if the ultrasonic vibration energy on the outer peripheral side surface of the hollow rotating body 12 is very small, the surface of the wafer 21 is irradiated with ultrasonic waves without significant attenuation. Therefore, the action of ultrasonic waves can be surely exhibited.

  On the other hand, simultaneously with the irradiation of the ultrasonic wave 14, the hollow rotating body 12 is rotated by a power source (not shown). As the hollow rotating body 12 rotates, the cleaning liquid 22 on the surface of the wafer 21 is forcibly drawn into a space sandwiched between the hollow rotating body 12 and the surface of the wafer 21, and the cleaning liquid 22 is in this space as indicated by an arrow. After passing through, it is forcibly discharged from this space. The rotation of the hollow rotating body 12 is rotated counterclockwise so as to accelerate the flow of the cleaning liquid 22 when the flow of the cleaning liquid 22 is from left to right in the drawing.

  Since the flow of the cleaning liquid 22 is accelerated by the rotation of the hollow rotator 12, it does not stagnate in the space between the hollow rotator 12 and the surface of the wafer 21, as compared with the case of spin cleaning using a conventional vibrator. Even passing through this space at a significantly faster speed. For this reason, it is possible to quickly wash away the foreign matter floating from the surface of the wafer 21 into the cleaning liquid 22 by the action of the ultrasonic wave 14 together with the flow of the high-speed cleaning liquid 22. As a result, the reattachment of foreign matter to the surface of the wafer 21 can be greatly reduced as compared with the case of spin cleaning using a conventional vibrator.

  As described above, according to the present invention, first, the effect of reducing the damage of the ultrasonic wave applied to the surface of the wafer can be obtained as in the case of the spin cleaning using the conventional vibrator. Next, the effect of greatly reducing the reattachment of foreign matter to the wafer surface can be obtained as compared with the case of spin cleaning using a conventional vibrator. Since these effects can be obtained at the same time, if the present invention is used, cleaning that can not be realized by a conventional spin cleaning method using a vibrating body and that has little damage to the wafer surface and high removal efficiency of foreign matters is achieved. Is possible.

  Note that minute irregularities may be provided on the outer peripheral side surface of the hollow rotating body 12 in order to enhance the scraping effect and further accelerate the flow of the cleaning liquid 22. For example, a groove parallel to the rotation axis direction may be formed on the outer peripheral side surface of the hollow rotator 12 by grinding, or linear protrusions are adhered to the outer peripheral side surface of the hollow rotator 12 parallel to the rotation axis direction. You may do it. In this case, the depth or height of the concave (groove) convex (projection) is arbitrary, but the height or depth below the film thickness of the cleaning liquid 22 so that the cleaning liquid 22 is in contact with the entire outer peripheral side surface of the hollow rotating body 12. Say it.

  Based on the above, the ultrasonic irradiation apparatus according to the first embodiment of the present invention will be described next with reference to FIGS. FIG. 2 is an external view of the main body portion of the ultrasonic irradiation apparatus according to the first embodiment of the present invention, in which a vibrating portion 30 including a vibrating body and an ultrasonic vibrator, and a hollow that encloses the vibrating body 31 through a minute gap. The rotating body 40 and the cap 50 that prevents the hollow rotating body 40 from jumping out are configured. In Example 1, the cleaning liquid is used as it is as the ultrasonic medium liquid.

  FIG. 3 is an explanatory diagram of the configuration of the vibrating unit. The vibrating unit 30 includes a vibrating body 31, an ultrasonic transducer 32, a support unit 33, a liquid feeding ring 34 including a liquid feeding tube 36, and a high-frequency power cable 37. Consists of. The vibrating body 31 is made of synthetic quartz and has, for example, a cylindrical shape having a length of 115 mm and a diameter of 15 mm. One end of the vibrating body 31 is connected to the ultrasonic transducer 32.

  Here, as the ultrasonic transducer 32, for example, a transducer having a vibration frequency of 1.5 MHz and a maximum output of 60 W is employed. As the vibration frequency of the ultrasonic vibrator 32, it is desirable to employ a vibrator having a frequency as high as possible, considering the damage that the ultrasonic waves give to the surface of the wafer to be cleaned. A frequency of at least 1 MHz is preferable. When ultrasonic vibration is generated in the vibrating body 31, the generated ultrasonic wave propagates to the entire vibrating body 31.

  The ultrasonic transducer 32 is fixed to a support portion 33 for supporting the entire main portion including the vibrator 31. A high frequency power cable 37 for supplying a high frequency power signal from a high frequency power source (not shown) to the ultrasonic transducer 32 extends from the support portion 33.

  A liquid feeding ring 34 is further fixed to one end of the vibrating body 31. The liquid feed ring 34 is provided with a plurality of cleaning liquid introduction passages 35 so as to penetrate the inside. As will be described later, a cylindrical space is provided between the outer peripheral side surface of the vibrating body 31 and the inner side surface of the rotating body. The cleaning liquid introduction passage 35 guides the cleaning liquid supplied from the outside to the cylindrical space. It is provided for the purpose.

  As described above, since air greatly attenuates ultrasonic waves, in order to propagate the ultrasonic waves generated by the vibrating body 31 to the outer rotating body 40, the cylindrical space formed between the two is used as an ultrasonic medium. It is necessary to fill with a cleaning liquid as a liquid. This cleaning liquid is continuously sent to the cylindrical space outside the vibrating body 31 so that the cylindrical space is always filled with the cleaning liquid.

  The end opening facing the rotating body side of the cleaning liquid introduction passage 35 is provided at a position in contact with the outer peripheral side surface of the vibrating body 31 so as to face one end of the cylindrical space. On the other hand, a liquid feed tube 36 extends from the opposite end opening and is connected to a liquid feed pump (not shown). By operating this liquid feed pump, the cleaning liquid is supplied to the cylindrical space outside the vibrating body 31. The number of the cleaning liquid introduction passages 35 is arbitrary, but here, for example, four cleaning liquid introduction passages 35 are installed every 90 degrees so as to surround the central axis of the vibrating body 31.

  FIG. 4 is a diagram illustrating the configuration of the hollow rotating body. The hollow rotating body 40 includes a cylindrical quartz tube 41 having a circular hole passing through the inside thereof, and a gear ring connected so as to sandwich the tube from both ends. 42 and a resin ring 43. The quartz tube 41, the gear ring 42, and the resin ring 43 have the same size both in the inner diameter and the outer diameter. Here, the hollow rotor 40 has an inner diameter of 19 mm, for example, and an outer diameter of 49 mm. Further, the length of the quartz tube 41 is, for example, 50 mm, the length (thickness) of each of the gear ring 42 and the resin ring 43 is 15 mm, and the total length of the hollow rotating body 40 is the sum of these. 80 mm.

  Further, the material of the quartz tube 41 is, for example, the same synthetic quartz as that of the vibrating body 31 and can propagate ultrasonic waves satisfactorily. The material of the gear ring 42 and the resin ring 43 is preferably a resin that is not easily subjected to chemical action by the cleaning liquid, and here, these are manufactured by machining from a fluororesin base material.

  A gear is formed on the outer peripheral side surface of the gear ring 42, and the hollow rotating body 40 can be rotated by meshing the gear with a gear connected to an external power source. Spacers 44 are provided on the inner side surfaces of the gear ring 42 and the resin ring 43. The spacer 44 was formed by leaving these portions uncut when both rings were cut out. The height of the spacer 44 is set to 1.8 mm here in consideration of some play necessary for rotation.

  The spacer 44 provides a space as uniform as possible between the outer peripheral side surface of the vibrating body 31 and the inner side surface of the hollow rotating body 40 when the hollow rotating body 40 is inserted into the vibrating body 31 and rotated. It is formed for the purpose of creating a cylindrical space. In addition, the inner side surface of the hollow rotator 40 is brought into contact with the outer peripheral side surface of the vibrating body 31 in as small an area as possible to reduce the friction and to smoothly rotate the hollow rotator 40. Here, as an example, four spacers 44 are installed every 90 degrees so as to surround the central axis of the hollow rotating body 40. However, the arrangement method of the spacers 44 is not limited to this, and serves the purpose described above. If possible, you can arrange it freely.

  Small hemispherical protrusions 45 and 46 are formed on the surfaces of the gear ring 42 and the resin ring 43 opposite to the quartz tube 41. The protrusions 45 and 46 are also formed by leaving both rings when they are machined by machining. Here, the height of the protrusions 45 and 46 is set to 1 mm. The protrusion 45 has the gear ring 42 in contact with the liquid-feeding ring 34 and the protrusion 46 has the resin ring 43 in contact with the cap 50 in an area as small as possible to reduce friction so that the rotation of the hollow rotating body 40 is smooth. Formed to be done.

  FIG. 5 is an explanatory view of the structure of the cap. The cap 50 is made of fluororesin, the outer diameter is 49 mm, which is the same as that of the hollow rotating body 40, and the diameter of the central hole 51 is 15 mm, which is the same as the diameter of the vibrating body 31. is there. The cap 50 is fixed to the tip of the vibrating body 31 so that the hollow rotating body 40 does not fall out of the vibrating body 31.

  As shown in FIG. 2, when these are assembled to form the main body portion 60 of the ultrasonic irradiation apparatus, the vibrating body 31 is inserted into the hole inside the hollow rotating body 40, and further, at the tip of the vibrating body 31. It is inserted into the hole 51 provided in the cap 50 and fixed. Thereby, a cylindrical space having a thickness of about 2 mm is formed outside the outer peripheral side surface of the vibrating body 31, and the hollow rotating body can freely rotate outside the vibrating body 31.

  Further, when the cleaning liquid is continuously supplied from the cleaning liquid introduction passage 35 to the cylindrical space outside the vibrating body 31, the cleaning liquid continues to flow in the direction toward the cap 50 from the liquid feeding ring 34 in the cylindrical space. . The extra cleaning liquid that fills the cylindrical space from the space formed by the protrusion 45 between the liquid feeding ring 34 and the gear ring 42 or the protrusion 46 between the resin ring 43 and the cap 50. From the space formed by the above, it flows out and flows out onto the wafer to be cleaned.

  FIG. 6 is an overall configuration diagram of the ultrasonic irradiation apparatus, and a support 62 is fixed to a support base 61, and a motor 62 including a power transmission shaft 63 having a gear 64 installed at the tip is provided. is set up. The support base 61 is fixed to a mechanism (not shown) for supporting the entire body 60 of the ultrasonic irradiation apparatus and causing a predetermined movement.

  A power cable 65 extends from the motor 62 and is connected to a control device (not shown) to drive and control the motor 62. Each component is arranged so that the gear 64 attached to the tip of the power transmission shaft 63 meshes with the gear ring 42 of the hollow rotating body 40. The hollow rotating body 40 can be rotated by operating the motor 62.

  FIG. 7 is an explanatory diagram of a cleaning process using the ultrasonic irradiation apparatus of the present invention. A cleaning liquid 22 is supplied from the nozzle 23 to the surface of the wafer 21 to be cleaned, and a film of the cleaning liquid 22 is formed on the surface of the wafer 21. In order to quickly wash away foreign matter floating from the surface of the wafer 21 into the cleaning liquid 22, the wafer 21 is always rotated at a constant speed during the cleaning operation. In order for the film of the cleaning liquid 22 to maintain a constant thickness, it is necessary to adjust the balance between the supply amount of the cleaning liquid 22 from the nozzle 23 and the rotational speed of the wafer 21.

  The support base 61 is fixed to a drive mechanism (not shown) so that the central axis of the hollow rotating body 40 of the main body 60 of the ultrasonic irradiation apparatus is parallel to the surface of the wafer 21. Then, as shown in FIG. 7, a drive mechanism (not shown) is provided so that the outer peripheral side surface of the hollow rotating body 40 is in contact with the film of the cleaning liquid 22 formed on the surface of the wafer 21 and is not in contact with the surface of the wafer 21. The main body 60 of the ultrasonic irradiation apparatus is brought close to the wafer 21 so that the distance between the outer peripheral side surface of the hollow rotating body 40 and the surface of the wafer 21 becomes a predetermined cleaning distance d. . The cleaning distance d is optimized and set together with other parameters so that the removal efficiency of foreign matters from the surface of the wafer 21 is maximized.

  The vibrating body 31 is operated while supplying the cleaning liquid 22 for the ultrasonic medium into the main body 60 of the ultrasonic irradiation device, and the hollow rotating body 40 is further rotated. As a result, ultrasonic waves are irradiated from the outer peripheral side surface of the hollow rotator 40, and at the same time, the cleaning liquid 22 passes through the space between the outer peripheral side surface of the hollow rotator 40 and the surface of the wafer 21 by the rotation of the hollow rotator 40. Go. The foreign matter that has floated from the surface of the wafer 21 into the cleaning liquid 22 due to the action of ultrasonic waves is discharged from the space between the hollow rotating body 40 and the wafer 21 along the flow of the cleaning liquid 22, and further to FIG. As shown, the wafer 21 is spun off to the outside of the wafer 21 together with the cleaning liquid 22 as the wafer 21 rotates.

  FIG. 8 is an explanatory view of the movement of the wafer and the ultrasonic irradiation apparatus. The state that the operations of the wafer 21 and the main body 60 of the ultrasonic irradiation apparatus during the cleaning operation are looked down from above is shown. The wafer 21 is placed and fixed horizontally on a rotatable wafer chuck (not shown) so that the center of the wafer 21 and the center of rotation of the wafer chuck coincide. During the cleaning operation, the wafer 21 rotates at a constant speed around the center of rotation of the wafer.

  On the other hand, the main body 60 of the ultrasonic irradiation apparatus is fixed to one end of an arm 66, and the other end of the arm 66 is fixed to a rotation shaft 67 of the arm. The rotation shaft 67 of the arm 66 is connected to a power mechanism (not shown) and reciprocates at a constant speed. Therefore, the arm 66 and the main body 60 of the ultrasonic irradiation apparatus fixed to the tip of the arm 66 reciprocate on the wafer 21 as indicated by arrows. The rotational axis 67 of the arm 66 is perpendicular to the rotational movement surface of the wafer 21 so that the surface formed by the reciprocating motion of the main body 60 of the ultrasonic irradiation device is parallel to the rotational motion surface of the wafer 21. It is set up.

  Further, from the arm 66, nozzles 23 for pouring the cleaning liquid 22 onto the surfaces of the wafers 21 on both the front and rear sides with respect to the direction of movement of the main body 60 of the ultrasonic irradiation device extend. The reciprocating motion of the arm 66 causes the nozzle 23 to reciprocate together with the main body 60 of the ultrasonic irradiation device while maintaining the positional relationship between the main body 60 of the ultrasonic irradiation device and the two nozzles 23.

  The tip of each nozzle 23 is arranged such that the cleaning liquid 22 is supplied to a position on the wafer 21 that is spaced a certain distance from the main body 60 of the ultrasonic irradiation device. The cleaning liquid 22 supplied from the nozzle 23 to the surface of the wafer 21 wets and spreads on the wafer 21 due to the pressure at the time of supply and the rotation of the wafer 21, and a film of the cleaning liquid 22 is formed on the entire surface of the wafer 21. During the reciprocating motion of the main body 60 of the ultrasonic irradiation apparatus, the distance between the outer peripheral side surface of the hollow rotating body 40 constituting the main body 60 of the ultrasonic irradiation apparatus and the surface of the wafer 21, that is, the cleaning distance d is constant. Control to take the value of.

  The action of the ultrasonic wave irradiated from the hollow rotator 40 of the main body 60 of the ultrasonic irradiator only affects the long and narrow stripe-shaped region where the hollow rotator 40 and the cleaning liquid 22 are in contact with each other. As a result of the reciprocating motion of the main body 60 of the ultrasonic irradiation apparatus, the entire area of the wafer 21 is swept over the area irradiated with ultrasonic waves, and the entire surface of the wafer 21 is cleaned.

  In the first embodiment, the case where the main body portion 60 of the ultrasonic irradiation apparatus is installed at the tip of the arm 66 extending from the rotary shaft 67 that performs reciprocating rotational movement has been described. The method of movement is not limited to this. For example, the main body 60 of the ultrasonic irradiation apparatus is passed between two guide rails that run in parallel, and the main body 60 of the ultrasonic irradiation apparatus is configured to reciprocate linearly. You may do it.

  The spin cleaning apparatus is constituted by the ultrasonic irradiation apparatus including the support mechanism and the drive system, the cleaning liquid supply mechanism including the nozzle 23, the wafer chuck including the drive mechanism, and the like.

Using this spin cleaning apparatus, an experiment was conducted to confirm the effect. Here, a thermal oxide film having a thickness of 100 nm is formed on the surface of a silicon wafer having a diameter of 8 inches (200 mm), and about 30,000 silica (SiO ₂ ) fine particles having an average particle size of 0.15 μm are adhered to the surface. A sample was prepared. Using a wafer surface inspection apparatus, the number of silica particles adhering to the wafer surface was measured before and after cleaning, and how much silica particles were removed by the cleaning (removal rate) was calculated. As a guideline for evaluation, when 99% of the adhered fine particles were removed by washing, it was determined that the washing was completed.

  The vibration frequency of the ultrasonic wave was 1.5 MHz, and the output was 60 W. As the cleaning liquid, hydrogen-dissolved water in which hydrogen gas was dissolved in ultrapure water at a concentration of 1.5 m / L was used. The cleaning liquid was supplied at a flow rate of 1.5 L / min at positions 31 mm away from the center of the hollow rotator on both sides of the hollow rotator.

  The silicon wafer was rotated at a speed of 150 rpm. Moreover, the ultrasonic irradiation apparatus reciprocated on the wafer so that the center of the hollow rotating body moved at a speed of about 50 mm / sec. The distance between the outer peripheral side surface of the hollow rotating body 40 and the wafer surface, that is, the cleaning distance d was about 1 mm.

  First, only the ultrasonic wave was irradiated without rotating the hollow rotating body, and cleaning was performed in the same manner as the spin cleaning method using a normal vibrating body. As a result, it took 385 seconds on average to complete the cleaning, that is, 99% of the adhered fine particles.

  Next, the ultrasonic irradiation conditions were all the same, and the hollow rotating body was rotated at a speed of 100 rpm for cleaning. As a result, the average time required to complete the cleaning was reduced to 75 seconds. As described above, it has been confirmed by experiments that the configuration of Example 1 of the present invention greatly improves the removal efficiency of foreign matters attached to the wafer surface.

  Next, the ultrasonic irradiation apparatus according to the second embodiment of the present invention will be described with reference to FIG. 9. Since the basic apparatus configuration is the same as that of the first embodiment, the main part of the ultrasonic irradiation apparatus is described. I will explain only. FIG. 9 is a cross-sectional view of the main part of the ultrasonic irradiation apparatus according to the second embodiment of the present invention, and penetrates the inside of the hollow rotator 40 from the inner side surface of the hollow rotator 40 toward the outer peripheral side surface of the hollow rotator 40. Thus, a passage 47 that guides the cleaning liquid 22 as an ultrasonic medium liquid is formed and connected to a cleaning liquid injection port 48 formed on the outer peripheral side surface of the hollow rotating body 40.

  The direction of the passage 47 in the vicinity of each cleaning liquid ejection port 48 is formed so as to be oblique to the outer peripheral side surface of the hollow rotator 40, that is, to form a certain angle with the normal line of the outer peripheral side surface of the hollow rotator 40. . The passage 47 and the cleaning liquid injection port 48 are provided, for example, at three locations along the length direction of the hollow cylindrical body 40. Therefore, the number of the entire passage 47 and the cleaning liquid injection port 48 is 4 × 3. Become.

  The cleaning liquid 22 that is sent under pressure to the cylindrical space outside the vibrating body 31 is ejected from the cleaning liquid injection port 48 to the outside of the hollow rotating body 40 through the passage 47, and the cleaning liquid 22 is ejected. As a reaction, a force that rotates the hollow rotator 40 in the direction opposite to the direction in which the cleaning liquid 22 is jetted acts to rotate the hollow rotator 40. In this case as well, since the cleaning liquid sprayed from the cleaning liquid injection port 48 is the same as the cleaning liquid used for cleaning, the cleaning effect is not affected.

  Thus, in Embodiment 2 of the present invention, since the cleaning liquid injection port 48 is provided in the hollow rotator 40, the hollow rotator 40 can be rotated without using power from an external power source. . In the figure, there are four passages 47 and cleaning liquid injection ports 48 per cross section, but the number is not limited to four and any number may be provided. However, since processing will become difficult when there are too many, 2-8 pieces are suitable.

  Next, the ultrasonic irradiation apparatus according to the third embodiment of the present invention will be described with reference to FIG. 10. Since the basic apparatus configuration is the same as that of the first embodiment, only the configuration of the hollow rotating body is used. explain. FIG. 10 is a diagram illustrating the configuration of a hollow rotating body of the ultrasonic irradiation apparatus according to the third embodiment of the present invention. The hollow rotating body 40 includes a cylindrical quartz tube 41 having a circular hole penetrating therein, The gear ring 42 and the resin ring 43 are connected so as to be sandwiched from both ends. Here, as in the first embodiment, the hollow rotor 40 has an inner diameter of, for example, 19 mm and an outer diameter of 49 mm. Further, the length of the quartz tube 41 is, for example, 50 mm.

  The quartz tube 41 is made of, for example, the same synthetic quartz as that of the vibrator 31, and the outer peripheral surface of the quartz tube 41 is ground by a width of, for example, 0.5 mm and the depth is, for example, 0. A plurality of 3 mm grooves 49 are provided. By providing the groove 49, the contact area between the hollow rotator 40 and the cleaning liquid 22 is increased, so that the cleaning liquid 22 is more efficiently involved and discharged by the hollow rotator 40. This is effective for improving the flow of the cleaning liquid 22 in the sandwiched space.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations and conditions shown in the embodiments. For example, in the first embodiment, in order to rotate the hollow rotator, a gear is formed on a part of the hollow rotator and meshed with another rotating gear connected to a power source. The rotation drive mechanism is not limited to a gear. For example, the rotating body may be rotated by providing a roller having a certain elasticity at one end of the rotating shaft connected to the power source and pressing the roller against the outer peripheral side surface of the rotating body. In this case, as the material of the roller, it is desirable to use silicone rubber or the like that is not easily affected by the chemical action of the cleaning liquid.

  Moreover, in Example 3 of this invention, although the groove | channel was provided by the grinding process in the outer peripheral side surface of the hollow rotary body, if a micro unevenness | corrugation can be formed, it will not be restricted to a groove | channel. For example, a synthetic quartz linear member having a width of 1.0 mm and a thickness of 0.5 mm may be formed in advance, and the linear member may be bonded or melt bonded to the outer peripheral side surface of the hollow rotating body. .

Here, the following additional notes are disclosed regarding the embodiment of the present invention including Examples 1 to 3.
(Additional remark 1) The hollow rotary body provided with the cylindrical outer peripheral side surface,
Means for supporting the hollow rotating body and rotating the hollow rotating body about a central axis of the hollow rotating body;
E Bei and means for generating an ultrasonic vibration to the outer peripheral side surface of said hollow rotating body,
Means for generating ultrasonic vibration on the outer peripheral side surface of the hollow rotating body,
A columnar vibrator inserted into the hollow portion of the hollow rotor at a small interval from the hollow rotor;
A liquid that satisfies a minute interval between the vibrating body and the hollow rotating body and that propagates ultrasonic waves satisfactorily;
Means for generating ultrasonic vibrations on an outer peripheral side surface of the vibrating body;
An ultrasonic irradiation apparatus comprising:
(Appendix 2 ) Means for horizontally supporting the wafer and rotating the wafer in that state;
The ultrasonic irradiation apparatus according to appendix 1 ,
In order to support the ultrasonic irradiation device and to reciprocate the ultrasonic irradiation device in parallel with the wafer surface while the outer peripheral side surface of the hollow rotating body is separated from the surface of the wafer by a minute and constant distance. Means of
And a means for supplying a cleaning liquid to the wafer surface.
(Supplementary Note 3 ) The liquid supplied to the minute cylindrical space formed between the vibrating body and the hollow rotating body is the same as the cleaning liquid supplied to the surface of the wafer, and
The cleaning apparatus according to claim 2, further comprising means for continuously supplying from one end of the cylindrical space toward the other end.
(Additional remark 4 ) The means for rotating the said hollow rotary body around the said vibrating body is the 1st gear provided in cyclic | annular form in a part of outer peripheral side surface of the said hollow rotary body,
Note that one end portion is provided at the other end portion of the rotating shaft connected to the rotational power source, and includes a second gear arranged so as to mesh with the first gear. 2 or the cleaning apparatus according to Appendix 3 .
(Supplementary Note 5 ) A means for rotating the hollow rotating body around the vibrating body includes a roller at the other end of the rotating shaft, one end of which is connected to a rotational power source,
The cleaning apparatus according to appendix 2 or appendix 3 , characterized by comprising means for bringing the roller into contact with the outer peripheral side surface of the hollow rotating body.
(Additional remark 6 ) The means for rotating the said hollow rotating body around the said vibrating body is formed in the inside of the said hollow rotating body, and the cylindrical shape formed between the said vibrating body and the said hollow rotating body The cleaning apparatus according to appendix 2 or appendix 3 , characterized by comprising a discharge passage for ejecting the liquid supplied to the space so as to form a certain angle with the normal line of the outer peripheral side surface of the hollow rotating body.
(Additional remark 7 ) The unevenness | corrugation lower than the film thickness of the said washing | cleaning liquid supplied to the surface of the said wafer is formed in the outer peripheral side surface of the said hollow rotary body, It is any one of Additional remark 2 thru | or 6 characterized by the above-mentioned. Cleaning equipment.
(Supplementary note 8 ) The cleaning device according to any one of supplementary notes 2 to 7 , wherein the vibrating body and the hollow rotating body are made of synthetic quartz.
(Supplementary Note 9 ) A cleaning method, comprising: cleaning a wafer using the cleaning apparatus according to any one of Supplementary Notes 2 to 8 .

It is explanatory drawing of the fundamental structure of the spin cleaning method of this invention. It is an external view of the main-body part of the ultrasonic irradiation apparatus of Example 1 of this invention. It is a structure explanatory drawing of a vibration part. It is composition explanatory drawing of a hollow rotary body. It is a structure explanatory view of a cap. It is a whole block diagram of the main-body part of an ultrasonic irradiation apparatus. It is explanatory drawing of the washing | cleaning process using the ultrasonic irradiation apparatus of this invention. It is explanatory drawing of a motion of a wafer and an ultrasonic irradiation apparatus. It is sectional drawing of the principal part of the ultrasonic irradiation apparatus of Example 2 of this invention. It is composition explanatory drawing of the hollow rotary body of the ultrasonic irradiation apparatus of Example 3 of this invention. It is explanatory drawing of the spin cleaning method using the conventional ultrasonic nozzle. It is explanatory drawing of the spin cleaning method using the conventional vibrating body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultrasonic irradiation apparatus 11 Vibrating body 12 Hollow rotary body 13 Ultrasonic medium liquid 14 Ultrasonic 21 Wafer 22 Cleaning liquid 23 Nozzle 30 Vibrating part 31 Vibrating part 32 Ultrasonic vibrator 33 Supporting part 34 Liquid feeding ring 35 Cleaning liquid introduction channel 36 Liquid tube 37 High-frequency power cable 40 Hollow rotating body 41 Quartz tube 42 Gear ring 43 Resin ring 44 Spacer 45, 46 Protrusion 47 Passage 48 Cleaning liquid injection port 49 Groove 50 Cap 51 Hole 60 Body portion 61 of ultrasonic irradiation device 61 Support base 62 Motor 63 Power transmission shaft 64 Gear 65 Power cable 66 Arm 67 Rotating shaft 71 Wafer 72 Ultrasonic nozzle 73 Cleaning liquid 74 Irradiation point 75 Vibrating body 76 Ultrasonic vibrator 77 Nozzle

Claims (5)

A hollow rotating body having a cylindrical outer peripheral side surface;
Means for supporting the hollow rotating body and rotating the hollow rotating body about a central axis of the hollow rotating body;
E Bei means for generating ultrasonic vibration to the outer peripheral side surface of said hollow rotating body,
Means for generating ultrasonic vibration on the outer peripheral side surface of the hollow rotating body,
A columnar vibrator inserted into the hollow portion of the hollow rotor at a small interval from the hollow rotor;
A liquid that satisfies a minute interval between the vibrating body and the hollow rotating body and that propagates ultrasonic waves satisfactorily;
Means for generating ultrasonic vibrations on an outer peripheral side surface of the vibrating body;
An ultrasonic irradiation apparatus comprising: Means for horizontally supporting the wafer and rotating the wafer in that state;
The ultrasonic irradiation apparatus according to claim 1 ;
In order to support the ultrasonic irradiation device and to reciprocate the ultrasonic irradiation device in parallel with the wafer surface while the outer peripheral side surface of the hollow rotating body is separated from the surface of the wafer by a minute and constant distance. Means of
And a means for supplying a cleaning liquid to the wafer surface. Means for rotating the hollow rotating body around the vibrating body;
A first gear annularly provided on a part of the outer peripheral side surface of the hollow rotating body;
A second gear, one end of which is provided at the other end of the rotating shaft connected to the rotational power source, and is arranged to mesh with the first gear;
The cleaning apparatus according to claim 2, comprising: 5. The cleaning apparatus according to claim 3 , wherein unevenness lower than a film thickness of the cleaning liquid supplied to the surface of the wafer is formed on an outer peripheral side surface of the hollow rotating body. A cleaning method comprising: cleaning a wafer using the cleaning apparatus according to claim 2 .

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