JP2015019111A - Microbubble generation device and silicon wafer cleaning apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microbubble generation device and a silicon wafer cleaning apparatus that can supply microbubbles having high cleaning efficiency and a small bubble size to the outside, can reduce the size of the apparatus, and can improve a degree of freedom of arrangement of the apparatus.SOLUTION: A microbubble generation device 1 includes a microbubble generation mechanism 10, and a derivation conduit 20 for deriving microbubbles to the outside. The derivation conduit 20 includes a widened part 21, and a tube part 22. In the derivation conduit 20, the widened part 21 and the tube part 22 are connected to each other and communicated with each other. The widened part 21 is a hollow cylindrical shape using an axis z as a center axis, and has bottom surfaces 23 and 24, and a cylindrical peripheral surface 25, and communicated with an exhaust nozzle 11 of the microbubble generation mechanism 10 via one bottom surface 23 of the widened part 21, and communicated with the tube part 22 via the other bottom surface 24 thereof. The cross-sectional area perpendicular to a flow path axis z of the microbubbles of the widened part 21 is larger than the cross-sectional area perpendicular to the flow path axis z of the tube part 22.

Description

  The present invention relates to a microbubble generating apparatus and a silicon wafer cleaning apparatus including the microbubble generating apparatus.

  In recent years, in the manufacturing technology of a semiconductor LSI using a silicon wafer, the use of a wafer having a larger diameter and a finer processing technique are required. Furthermore, it is also necessary to solve problems such as maintenance and improvement of product quality and reduction of production cost due to complicated processes.

  In particular, in many fields of semiconductor LSI manufacturing technology using silicon wafers, so-called wet processing steps including processing with various solutions are indispensable steps. Among such wet processing steps, particularly important steps are a cleaning step, an etching step, and the like. Conventionally, in these wet processing steps, improvements have been repeated mainly in terms of selection of the type, concentration, processing temperature, time, and the like of the solution (for example, see Non-Patent Document 1). However, these conventional techniques have not been sufficient to satisfy the demands associated with the recent need for finer processing techniques, complicated processes, higher cleaning, and lower costs. Furthermore, in recent years, due to demands for stricter environmental protection measures and cost reduction of waste liquid treatment, treatments such as dilute chemical cleaning and chemical-less cleaning have been desired.

  In recent years, research and development for applying microbubbles to semiconductor cleaning has been promoted (see, for example, Patent Document 1). However, in the conventional cleaning apparatus using microbubbles, the nozzle of the microbubble generating apparatus that generates microbubbles is installed at the bottom of the cleaning tank, and the microbubble generating apparatus takes up space in the cleaning tank. The installation of other devices became an obstacle, and it took time to install the devices. In order to solve this inconvenience, there is a cleaning apparatus in which a buffer tank is provided separately from the cleaning tank, and a microbubble generating device is provided in the buffer tank. However, this cleaning device requires a larger installation space. For this reason, an in-line arrangement in which the micro-bubble generating device is arranged in a conduit for circulating the cleaning liquid in the cleaning tank is preferable, and there has conventionally been a cleaning device having a micro-bubble generating device arranged in-line.

JP 2008-103701 A

Edited by Hattori Satoshi "New Silicon Wafer Surface Clean Technology" Realize (2000)

  However, when the microbubble generator is installed in a narrow pipe, the microbubbles are combined near the outlet of the microbubble generator, and the bubble size is increased. In particular, in the case of a microbubble generator with eddy currents, bubbles are gathered at the center of the pipeline due to the Counder effect due to eddy currents, and the bubble size has become larger. For this reason, the conventional cleaning apparatus has a problem that the generation efficiency of the microbubbles is lowered, and the cleaning performance of the silicon wafer is lowered.

  An object of the present invention is to provide a microbubble generating apparatus and a silicon wafer cleaning apparatus capable of improving the generation efficiency of microbubbles and improving the cleaning performance of a silicon wafer.

  In order to achieve the above object, a microbubble generating apparatus according to the present invention includes a microbubble generating mechanism that generates microbubbles, and the microbubble generating mechanism that derives microbubbles generated by the microbubble generating mechanism. The microbubble generating mechanism includes a spout for ejecting microbubbles to the outside, and the leadout conduit includes a widened portion and a pipe portion that communicate with each other, and the widened portion is a microbubble. The channel cross-sectional area is larger than that of the tube portion, and the microbubble generating mechanism is connected to the widened portion.

  Preferably, the microbubble generating mechanism and the pipe part are connected to the widening part so that the microbubbles flow axis in the widening part and the microbubbles flow axis in the pipe part extend in the same direction. ing.

  More preferably, the flow direction of the microbubbles in the widened portion and the flow direction of the microbubbles in the tube portion are opposite to each other.

  Preferably, the microbubble generating mechanism and the pipe part are connected to the widening part so that the microbubbles flow axis in the widening part and the microbubbles flow axis in the pipe part intersect each other. ing.

  More preferably, the microbubble generating mechanism and the tube portion are connected to the widened portion so that the flow path axis in the widened portion and the flow channel axis in the tubular portion are orthogonal to each other.

  Preferably, the microbubble generating mechanism is connected to the widening portion so that the jet port is disengaged from the flow axis of the microbubble in the pipe portion.

Preferably, the widened portion has a circular channel cross section.
Preferably, the pipe part is provided in the vicinity of the jet port in the widened part.

  A silicon wafer cleaning apparatus according to the present invention is a silicon wafer cleaning apparatus for cleaning a silicon wafer provided with the above-described microbubble generating apparatus, and stores a cleaning liquid that stores a silicon wafer as a body to be cleaned, And a pump device having a pump and a conduit for circulating the cleaning liquid in the cleaning tank, wherein the microbubble generator is provided in a conduit of the pump device.

  According to the microbubble generating device of the present invention, the microbubble generating mechanism for generating microbubbles has a larger flow path cross-sectional area of the microbubbles than the pipe portion in the outlet conduit for leading out the generated microbubbles. Since it is connected to the widened portion, the microbubbles ejected from the ejection port of the microbubble generating device are dispersed without interfering with each other in the widened portion. For this reason, it is possible to prevent the generated micro bubbles from being combined with each other to become a bubble having a large bubble size with a low cleaning effect, and the generated micro bubbles retain the bubble size in the widened portion. Microbubbles of a small bubble size that are stabilized and have a high cleaning effect can be supplied to the outside from the tube portion. Thus, according to the microbubble generator according to the present invention, microbubbles having a small bubble size with a high cleaning effect can be provided to the outside, the generation efficiency of microbubbles can be improved, and the cleaning performance can be improved. Can be improved.

  In addition, the microbubble generating device according to the present invention has a simple structure and can be downsized, and in a device to be applied, for example, a silicon wafer cleaning device, it is possible to improve the degree of freedom of device arrangement. it can.

  Furthermore, the silicon wafer cleaning apparatus according to the present invention can improve the cleaning performance. In addition, the device can be reduced in size, and the degree of freedom in device design can be improved.

It is a figure which shows schematic structure of the microbubble production | generation apparatus which concerns on the 1st Embodiment of this invention, Fig.1 (a) is a perspective view, FIG.1 (b) is a front view. It is a figure which shows schematic structure of a silicon wafer cleaning apparatus provided with the microbubble production | generation apparatus of FIG. It is a figure which shows schematic structure of the microbubble production | generation apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows schematic structure of the microbubble production | generation apparatus which concerns on the 3rd Embodiment of this invention. It is a figure which shows schematic structure of the microbubble production | generation apparatus which concerns on the 4th Embodiment of this invention. It is a figure which shows schematic structure of the microbubble production | generation apparatus which concerns on the 5th Embodiment of this invention. It is a figure which shows schematic structure of the microbubble production | generation apparatus which concerns on the 6th Embodiment of this invention. It is a figure which shows schematic structure of the microbubble production | generation apparatus which concerns on the 7th Embodiment of this invention. It is a figure which shows the modification of the microbubble production | generation apparatus of FIG. It is a figure which shows the other modification of the microbubble production | generation apparatus of FIG. It is a figure which shows the silicon wafer cleaning apparatus in Example 1. FIG. It is a figure which shows the silicon wafer cleaning apparatus in the comparative example 1. It is a figure which shows the silicon wafer cleaning apparatus in the comparative example 2. It is a figure which shows the silicon wafer cleaning apparatus in the comparative example 3. It is a figure which shows the microbubble production | generation apparatus of the silicon wafer cleaning apparatus of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a microbubble generating apparatus according to a first embodiment of the present invention, FIG. 1 (a) is a perspective view, and FIG. 1 (b) is a front view.

  As shown in FIG. 1, the microbubble generating device 1 according to the first exemplary embodiment of the present invention includes a microbubble generating mechanism 10 that generates microbubbles M, and a microbubble M generated by the microbubble generating mechanism 10. And a lead-out conduit 20 for leading the outside to the outside.

  The microbubble generating mechanism 10 includes an ejection port 11 for ejecting the generated microbubbles to the outside. The microbubble generation mechanism 10 is supplied with a liquid and a gas, and ejects micro bubbles having a diameter of the order of μm together with the liquid. The microbubble generation mechanism 10 is preferably accompanied by a liquid flow when generating microbubbles. For example, a swirl liquid flow type, a static mixer type, an ejector type, a cavitation type, a venturi type, a centrifugal pump and a swirl type micro It is preferable to use a combination of bubble generators and a pressure dissolution type microbubble generation method. In the silicon wafer cleaning device described later, it is necessary to transport the liquid containing the generated microbubbles to the cleaning tank. When the microbubbles are generated, the microbubbles are transferred to the cleaning tank. This is because it is possible to omit an additional transfer device for the purpose. However, the microbubble generating mechanism 10 may be one in which the liquid is stationary and does not flow when the microbubble is generated. In this case, in the silicon wafer cleaning apparatus described later, a transport apparatus for transporting the liquid containing microbubbles to the cleaning tank is required. The microbubble generating mechanism 10 in which the liquid does not flow when the microbubbles are generated and the liquid is stationary includes a pore type, a rotary type, an ultrasonic type, a vapor condensation type, and an electrolysis type. Some use the microbubble generation method.

  The outlet conduit 20 includes a widened portion 21 and a tube portion 22. In the outlet conduit 20, the widened portion 21 and the tube portion 22 are connected to each other and communicate with each other. The microbubble generating mechanism 10 is connected to the widened portion 21, and ejects microbubbles M spreading in a conical shape with the axis z as the central axis into the enlarged diameter portion 21 from the ejection port 11.

  The widened portion 21 has a hollow cylindrical shape with the axis z as a central axis, and has bottom surfaces 23 and 24 and a cylindrical peripheral surface 25, and a microbubble generating mechanism is provided via one bottom surface 23 of the widened portion 21. Ten spouts 11 communicate with each other, and the pipe portion 22 communicates with the other bottom surface 24. The ejection port 11 of the microbubble generating mechanism 10 is a cylindrical opening with the axis z as the central axis, and the pipe portion 22 is a cylindrical pipe with the axis z as the central axis. That is, in the microbubble generating device 1, the channel axis of the microbubbles flowing in the widened portion 21 and the channel axis of the microbubbles flowing in the tube portion 22 are the same axis z, and the microbubbles are mutually It is designed to flow in the same direction.

  In the outlet conduit 20, the area of the microbubble channel cross section of the widened portion 21, that is, the area of the cross section orthogonal to the axis z that is the microbubble channel axis is the area of the microbubble channel cross section of the tube portion 22. That is, it is larger than the area of the cross section perpendicular to the axis z which is the channel axis of the microbubble. The area of the channel cross section of the widened portion 21 is larger than the area of the cross section (channel cross section) orthogonal to the axis z of the ejection port 11 of the microbubble generating mechanism 10. Further, the area of the channel cross section of the widened portion 21 and the length in the channel axis z direction are such that the microbubbles ejected from the microbubble generating mechanism 10 diffuse and stabilize while maintaining the bubble size. Is set to

  Regarding the size of the widening portion 21, the flow rate of the liquid supplied to the microbubble generation mechanism 10, the type and concentration of the supplied liquid, the temperature, the flow rate of the gas supplied to the microbubble generation mechanism 10, or the microbubble generation mechanism 10 It depends on the specifications. The specifications of the microbubble generation mechanism 10 include, for example, the type, that is, the microbubble generation method, size, bubble generation efficiency, and the like.

  For example, the diameter d1 of the channel cross section of the widened portion 21 is 50 to 500 mm, preferably 75 to 300 mm, more preferably 100 to 200 mm, and the length l1 of the widened portion 21 in the axis z direction is 50 to 500 mm, Preferably it is 75-400 mm, More preferably, it is 100-300 mm, and the capacity | capacitance of the widening part 21 is 0.1-50 l (liter), Preferably it is 0.2-10 l, More preferably, it is 0.5-5 l. Further, the ratio of the diameter of the channel cross section of the widened portion 21 to the diameter of the channel cross section of the jet port 11 is relatively small as in the swirling liquid flow method, and the diameter of the jet port is relatively small in a spray shape (conical shape). In a microbubble generating mechanism of a type that ejects bubbles, it is 10 to 100 times, preferably 15 to 80 times, and more preferably 20 to 60 times. Moreover, in the microbubble generating mechanism of the type in which the diameter of the ejection port is relatively large and the microbubbles are ejected in the shape of the ejection port as in the ejector type, the widened portion 21 with respect to the diameter of the flow path cross section of the ejection port 11 The ratio of the diameters of the channel cross-sections is 1.5 to 50 times, preferably 2 to 40 times, and more preferably 3 to 30 times. For the diameter d2 of the cross section of the flow path of the pipe part 22, a value suitable for the liquid flow rate in the widened part 21 may be selected.

  The size of the widened portion 21 is not limited to that described above, and is set according to the specific conditions described above. When the diameter d1 of the widened portion 21 is too small, when the length l1 of the widened portion 21 is too short, or when the capacity of the widened portion 21 is too small, the generated bubble size becomes large. When the diameter d1 is too large, when the length l1 of the widened portion 21 is too long, or when the capacity of the widened portion 21 is too large, a large space is required for installing the microbubble generator 1, and the use of liquid The amount will increase. The size of the widened portion 21 is preferably set in consideration of such matters.

  As described above, in the microbubble generating device 1 according to the first embodiment of the present invention, the microbubble generating mechanism 10 is connected to the channel breaker via the widened portion 21 having a large channel cross-sectional area of the outlet conduit 20. The microbubbles that are connected to the pipe portion 22 having a small area and are generated by the microbubble generating mechanism 10 are first ejected to the widened portion 21 having a wide channel cross-sectional area. For this reason, the ejected microbubbles can be diffused without colliding with the pipe wall, and the microbubbles do not interfere with each other to form a large bubble size bubble. In the widened portion 21, the liquid can be diffused until it is stabilized in the liquid. Therefore, microbubbles having a high cleaning effect and maintaining a small bubble size when ejected can be supplied from the widened portion 21 to the tube portion 22, and the microbubbles having this small bubble size are derived to the outside. Can do.

  The microbubble generating device 1 includes a microbubble generating mechanism 10 and a lead-out conduit 20 having a widened portion 21 and a tube portion 22, and the configuration is simple.

  Thus, the microbubble generator 1 according to the first embodiment of the present invention can provide microbubbles with a small bubble size having a high cleaning effect to the outside. In addition, the microbubble generating device 1 has a simple structure and can be downsized.

  In the microbubble generating device 1 according to the present embodiment, the shape of the widened portion 21 is a hollow cylindrical shape, but the shape of the widened portion 21 is not limited to this. For example, the widened portion 21 may have a hollow rectangular parallelepiped shape.

  Next, a silicon wafer cleaning apparatus including the microbubble generating apparatus 1 according to the first embodiment of the present invention will be described. FIG. 2 is a diagram showing a schematic configuration of a silicon wafer cleaning apparatus provided with the microbubble generating apparatus 1.

  As shown in FIG. 2, the silicon wafer cleaning apparatus 100 includes a cleaning tank 101 in which a cleaning liquid 102 is stored, a pump 103 for circulating the cleaning liquid 102 in the cleaning tank 101, and pipe lines 104 and 105. The pump 103 sucks the cleaning liquid 102 from the cleaning tank 101 through the pipe line 104 and supplies the cleaning liquid 102 to the cleaning tank 101 through the pipe line 105. The silicon wafer cleaning apparatus 100 includes a microbubble generating apparatus 1. The microbubble generator 1 is provided in the middle of the pipe line 105.

  Below, the cleaning process of the silicon wafer W in the silicon wafer cleaning apparatus 100 will be described.

  For example, a plurality of silicon wafers W cut from a single crystal silicon ingot are arranged at equal intervals on a holder (not shown) so that the surfaces face each other, and are arranged in the cleaning tank 101 and stored in the cleaning liquid 102 stored in the cleaning tank 101. Soak in. Next, the pump 103 is operated to circulate the cleaning liquid 102 between the cleaning tank 101 and the pipe lines 104 and 105. Further, the microbubble generating device 1 is operated to generate microbubbles in the cleaning liquid 102 circulated by the microbubble generating mechanism 10, and the microbubbles are ejected to the widened portion 21 of the outlet conduit 20 through the ejection port 11. , Stabilize microbubbles. Then, the cleaning liquid 102 containing the stabilized microbubbles of small bubble size is led out to the pipe line 105 through the pipe part 22, and the microbubbles are supplied into the cleaning tank 101. In the cleaning tank 101, the cleaning liquid 102 is filled with microbubbles, and the silicon wafer W is cleaned by the cleaning liquid 102 containing microbubbles that circulates.

In the silicon wafer cleaning apparatus 100 including the microbubble generating apparatus 1 according to the first embodiment of the present invention described above, microbubbles having a small bubble size with a high cleaning effect are supplied into the cleaning tank 101. The cleaning power is high, the silicon wafer W can be cleaned with a high degree of cleaning, and the cleaning performance of the silicon wafer is improved. In addition, since the microbubble generator 1 is small as described above, in the silicon wafer cleaning apparatus 100 The degree of freedom of the arrangement position is high, and the degree of freedom in designing the silicon wafer cleaning apparatus 100 can be improved. Moreover, the silicon wafer cleaning apparatus 100 can be reduced in size, can be used and moved easily, and can be handled easily.

  Next, another embodiment of the microbubble generating apparatus according to the present invention will be described. Hereinafter, only parts different from the microbubble generating apparatus 1 according to the first embodiment of the present invention will be described, and the same parts will be denoted by the same reference numerals and description thereof will be omitted.

  FIG. 3 is a diagram showing a schematic configuration of a microbubble generating apparatus according to the second embodiment of the present invention. The microbubble generator 200 according to the second embodiment of the present invention differs from the microbubble generator 1 only in the structure of the outlet conduit.

  As shown in FIG. 3, in the microbubble generating apparatus 200, the outlet conduit 210 is different in the connection position of the tube portion 22 with respect to the widened portion 21. In the outlet conduit 210, the pipe portion 22 has a channel axis z 1 that is not the same as the channel axis z of the microbubbles M in the widened portion 21, but is shifted in parallel.

  In the microbubble generating apparatus 1 according to the first embodiment, the flow path axis (axis z) of the pipe line 22 is the same as the flow axis (axis z) of the microbubbles in the widened portion 21, and microbubble generation is performed. Since there is an inlet opening of the pipe line 22 in the microbubble jet direction of the jet port 11 of the mechanism 10, when a vortex is generated in the widened portion 21, an air passage is formed at the center of the vortex, and this air causes The bubble size of the bubble may increase. On the other hand, in the microbubble generating apparatus 200 according to the second embodiment, the tube portion 22 has its flow channel axis z1 offset in parallel to the flow channel axis z of the microbubble M in the widened portion 21. Therefore, it is possible to prevent the generation of a vortex in the widened portion 21 and supply more microbubbles having a small bubble size to the tube portion 22. This embodiment is particularly effective in the microbubble generating mechanism 10 that uses a microbubble generating method that generates eddy currents. Microbubble generation methods for generating vortex flow include a swirling liquid flow method, a static mixer method, or a combination of a centrifugal pump and a swirling flow microbubble generator.

  4-7 is a figure which shows the schematic structure of the microbubble production | generation apparatus which concerns on the 3rd-6th embodiment of this invention, respectively.

  The microbubble generator 300 according to the third embodiment of the present invention differs from the microbubble generator 1 only in the structure of the outlet conduit. As shown in FIG. 4, in the microbubble generating device 300, the outlet conduit 310 is different in the connection position of the tube portion 22 with respect to the widened portion 21. In the outlet conduit 310, the pipe portion 22 has a flow path axis z 1 that is not the same as the flow path axis z of the microbubbles M in the widened portion 21, and is shifted in parallel. Are connected on the bottom surface 23 to which the microbubble generating mechanism 10 is attached. With this configuration, the flow direction of microbubbles in the widened portion 21 and the flow direction of microbubbles in the tube portion 22 are opposite to each other.

  The microbubble generator 400 according to the fourth embodiment of the present invention differs from the microbubble generator 300 only in the structure of the outlet conduit. As shown in FIG. 5, in the microbubble generating device 400, the lead-out conduit 410 is different in the shape of the widened portion 411. In the outlet conduit 410, the widening portion 411 has a bottom surface 412 to which the microbubble generating mechanism 10 and the tube portion 22 are connected, not perpendicular to the flow path axes z and z1, and the tube from the connection position of the microbubble generating mechanism 10. The bottom surface 412 is formed so as to be away from the opposite bottom surface 24 toward the connection position direction of the portion 22.

  The microbubble generator 500 according to the fifth embodiment of the present invention differs from the microbubble generator 1 only in the structure of the outlet conduit. As shown in FIG. 6, in the microbubble generating device 500, the outlet conduit 510 is different in the connection position of the tube portion 22 with respect to the widened portion 21. In the outlet conduit 510, the pipe part 22 has a flow path axis z <b> 1 that is not the same as the flow path axis z of the microbubble M in the widened part 21, but is orthogonal to each other. That is, the tube portion 22 is erected on the cylindrical peripheral surface 25 of the widened portion 21. In the present embodiment, the tube portion 22 is erected on the edge portion on the bottom surface 23 side. With this configuration, the microbubble flow direction in the widened portion 21 and the microbubble flow direction in the tube portion 22 are orthogonal to each other. In addition, although the pipe part 22 shall be attached to the bottom face 23 side in which the microbubble production | generation mechanism 10 is attached in the widening part 21, you may provide the pipe part 22 in the bottom face 24 side.

  The microbubble generator 600 according to the sixth embodiment of the present invention differs from the microbubble generator 500 only in the structure of the outlet conduit. As shown in FIG. 7, in the microbubble generator 600, the outlet conduit 610 is different in the shape of the widened portion 611. In the outlet conduit 610, the widened portion 611 has a channel cross-sectional area from the bottom surface 23 to which the microbubble generating mechanism 10 is connected to the opposed bottom surface 24 instead of the cylindrical surface 612 to which the tube portion 22 is connected. Is formed to decrease. That is, as shown in FIG. 7, the peripheral surface 612 of the widened portion 611 forms a substantially truncated cone peripheral surface, and the widened portion 611 is formed so that the cross section along the flow path axis z is trapezoidal. . This is to make it difficult for bubbles to accumulate in the widened portion 611.

  The microbubble generators 300 to 600 according to the third to sixth embodiments of the present invention have the same effects as the microbubble generator 200 according to the second embodiment of the present invention. it can.

  FIG. 8 is a diagram showing a schematic configuration of a microbubble generating apparatus according to the seventh embodiment of the present invention. The microbubble generator 700 according to the seventh embodiment of the present invention differs from the microbubble generator 1 only in the structure of the outlet conduit.

  As shown in FIG. 8, in the microbubble generating device 700, the outlet conduit 710 supplies the liquid into the widened portion 21 on the bottom surface 23 to which the microbubble generating mechanism 10 is attached. The difference is that 711 is connected. In the present embodiment, two supply pipelines 711 are provided at the edge of the bottom surface 23, but the number of supply pipelines 711 is not limited to this.

  In the microbubble generating device 700 according to the seventh exemplary embodiment of the present invention, in the widened portion 21, the supply of the liquid into the widened portion 21 is performed on the edge of the bottom surface 23 to which the microbubble generating mechanism 10 is attached. Since the duct 711 is provided, the liquid in the region (region p) in the vicinity of the edge of the bottom surface 23 in the widened portion 21 can be flowed to prevent the liquid from staying in the region p.

  The microbubble generating apparatus according to the present invention is not limited to the shape and configuration of the microbubble generating apparatus according to each embodiment of the present invention, and may be, for example, a combination of the embodiments. Further, for example, the shape of the widened portion 21 of the microbubble generating device 1 is a hollow cone shape (conical truncated cone shape) that spreads in the flow direction of the microbubbles with the flow path axis z as the central axis, as shown in FIG. Alternatively, as shown in FIG. 10, it may have a shape that spreads in the flow direction of the microbubbles with the flow path axis z as the central axis and narrows again from a predetermined position. Moreover, the pipe part 22 may be arrange | positioned so that the flow-path axis z1 may cross | intersect diagonally, without orthogonally crossing with respect to the flow-path axis z of a wide part.

  The direction of installation of the microbubble generator according to the present invention is not limited to the direction shown in FIGS. 1 and 3 to 10. However, in order to make it difficult for bubbles to stay in the widened portion 21, it is preferable that the tube portion 22 be as high as possible. For example, the installation direction may be the installation direction in which the microbubble generation device illustrated in FIGS. 4 and 5 is rotated 90 degrees to the right, and the installation direction in which the microbubble generation device illustrated in FIGS.

There is no restriction | limiting in particular also about the material of the microbubble production | generation apparatus which concerns on this invention.
Further, the microbubble generating device according to the present invention may be applied to a cleaning device other than a silicon wafer cleaning device, for example, a parts cleaning machine, a washing machine, or the like. Furthermore, you may install in the tank for a bathtub, a ginger, an aquarium tank, or an appreciation fish. In this case, for example, it is conceivable to connect to a circulation path of a circulation filtration filter. Moreover, you may provide in the middle of the hose of a household shower, or the middle of a water pipe.

  Specifically, the microbubble generator according to the present invention can be applied to an alkaline cleaning liquid having an etching power.

  It is known that the etching rate in an alkaline cleaning liquid having etching power is improved by the action of microbubbles (see Patent Document 1). The silicon wafer cleaning apparatus 100 having the microbubble generating apparatus according to the present invention can improve the etching rate equivalent to the conventional silicon wafer cleaning apparatus in which the conventional microbubble generating apparatus is immersed in the cleaning tank.

  First, a polysilicon layer was deposited to a thickness of about 1 μm by CVD on a mirror surface of a 200 mm diameter silicon wafer to prepare an evaluation sample. Next, the thickness of the polysilicon layer of the sample before cleaning was measured using Nanospec (manufactured by Nanometrics).

  Next, as shown in FIG. 11, the sample was cleaned using a silicon wafer cleaning apparatus 110 (Example 1). The silicon wafer cleaning apparatus 110 is the same as the silicon wafer cleaning apparatus 100 shown in FIG. 2 except that the microbubble generating apparatus 500 having the shape shown in FIG. 6 is used as the microbubble generating apparatus. For the microbubble generating mechanism 500, a swirling liquid flow type (M2-MS / PTFE type manufactured by Nano Planet Research Laboratory) was used. The widened portion has a shape of diameter 100 mm × length 200 mm and is made of quartz glass. In the cleaning process, specifically, in the cleaning tank 101, an alkaline cleaning liquid having an etching power as a cleaning liquid, for example, TECHNICLEAN 200EF (main component: alkaline inorganic salt, anionic surfactant, nonionic surfactant, water ) Was diluted 20 times with ultrapure water. Also, the cleaning solution used for each cleaning process was discarded and a new cleaning solution was used. 20 L (liter) of the cleaning solution was placed in the cleaning tank 101, the temperature of the cleaning solution was set to 50 ° C., and the sample was immersed in the cleaning solution for 30 minutes. Thereafter, the washed sample was taken out, placed in a 20 ° C. ultrapure water tank, and rinsed for 10 minutes. Thereafter, this sample was dried with a spin dryer.

  Next, the thickness of the polysilicon layer of the sample was measured in the same manner as the measurement before the cleaning for the sample according to Example 1 that was cleaned as described above.

  In addition, as shown in FIG. 12, the sample was cleaned by a silicon wafer cleaning apparatus 800 having no microbubble generating apparatus (Comparative Example 1). That is, the cleaning process was performed without using the microbubbles and without circulating the cleaning liquid.

  Further, as shown in FIG. 13, the silicon wafer cleaning apparatus 900 in which one nozzle portion of the microbubble generating apparatus (M2-MS / PTFE type manufactured by Nano Planet Research Laboratories) is disposed on the bottom surface of the cleaning tank 901 is used. The sample was washed (Comparative Example 2).

  As shown in FIG. 14, a Teflon (PFA) tube 1004 having an outer diameter of 3/4 inch and an inner diameter of 5/8 inch is provided at the microbubble outlet of the microbubble generating mechanism 1003 of the microbubble generating device 1002. Were directly connected (see FIG. 15), and the sample was cleaned by the silicon wafer cleaning apparatus 1000 in which the Teflon tube 1004 was introduced into the cleaning tank 1001 (Comparative Example 3).

  The cleaning process in Comparative Examples 1 to 3, that is, the cleaning tank, the cleaning liquid composition, the cleaning liquid amount, the cleaning time, the rinsing time, the drying method, and the like are the same as those in the first embodiment. Further, the sample after washing was measured in the same manner as in Example 1.

  The etching rate was calculated from the thicknesses of the polysilicon layers before and after the cleaning of the sample of Example 1 and the samples of Comparative Examples 1 to 3. The results are shown in Table 1. In Table 1, the liquid flow rate is the flow rate of the cleaning liquid introduced into the microbubble generating device, and the introduced air amount is the flow rate of air introduced into the microbubble generating device.

  As shown in Table 1, according to the silicon wafer cleaning apparatus (Example 1) according to the present invention, a conventional silicon wafer cleaning apparatus (Comparative Example 2) in which a conventional microbubble generator is immersed in a cleaning tank; It can be seen that the same etching rate improvement effect can be obtained. That is, it can be seen that the silicon wafer cleaning apparatus (Example 1) according to the present invention can effectively generate microbubbles.

  The etch rate of Example 1 is slightly lower than that of Comparative Example 2, but this is considered to be due to the fact that the liquid flow rate and air introduction amount are less in Example 1, and Example 1 is a comparative example. It is considered that there is a microbubble generation capability substantially equivalent to Example 2.

  In Comparative Example 3 in which the Teflon tube was directly connected to the microbubble outlet of the microbubble generating mechanism, the Teflon tube was too thin, and eddy currents were generated to generate large bubbles. No significant improvement in the etching rate was observed as compared with Comparative Example 1 without microbubbles.

  Thus, according to the silicon wafer cleaning apparatus according to the present invention, various contaminants (particles, ions) on the surface of the silicon wafer are equivalent to the conventional silicon wafer cleaning apparatus in which the conventional microbubble generator is immersed in the cleaning tank. , Metal, organic matter, etc.) can be improved.

1,200,300,400,500,600,700 Microbubble generating device 10 Microbubble generating mechanism 11 Outlet 20, 210, 310, 410, 510, 610 Outlet conduit 21, 411, 611 Widened portion 22 Pipe portion 23, 24,412 Bottom surface 25,612 Peripheral surface 100 Silicon wafer cleaning device 101 Cleaning tank 102 Cleaning liquid 103 Pump 104, 105 Pipe line 711 Supply pipe line z, z1 Axis M Micro bubble W Silicon wafer

Claims (9)

A microbubble generating mechanism for generating microbubbles;
An outlet conduit connected to the microbubble generating mechanism to derive microbubbles generated by the microbubble generating mechanism;
The microbubble generating mechanism includes a jet outlet for jetting microbubbles to the outside, and the outlet conduit includes a widened portion and a pipe portion that communicate with each other, and the widened portion has a cross-sectional area of the microbubble that is smaller than that of the pipe portion. Largely, the micro-bubble generating device is connected to the widening portion.   The microbubble generating mechanism and the pipe part are connected to the widening part so that the microbubbles flow axis in the widening part and the microbubbles flow axis in the pipe part extend in the same direction. The microbubble generating device according to claim 1.   The microbubble generating apparatus according to claim 1, wherein a flow direction of the microbubbles in the widening portion and a flow direction of the microbubbles in the tube portion are opposite to each other.   The microbubble generating mechanism and the tube portion are connected to the widened portion so that the microbubble channel axis in the widened portion and the microbubble flow axis in the tubular portion intersect each other. The microbubble generating device according to claim 1.   5. The microbubble generating mechanism and the pipe part are connected to the widened part so that a flow path axis in the widened part and a flow axis in the pipe part are orthogonal to each other. Microbubble generator.   The said micro bubble production | generation mechanism is connected to the said wide part so that the said jet nozzle may remove | deviate from the flow-path axis line of the micro bubble in the said pipe part, The any one of Claim 1 thru | or 5 characterized by the above-mentioned. Microbubble generator.   The micro-bubble generating device according to any one of claims 1 to 6, wherein the widened portion has a circular channel cross section.   The micro-bubble generating device according to any one of claims 1 to 7, wherein the pipe portion is provided in the vicinity of the ejection port in the widened portion. A silicon wafer cleaning apparatus for cleaning a silicon wafer comprising the microbubble generating apparatus according to any one of claims 1 to 8,
A cleaning tank for storing a cleaning liquid that contains a silicon wafer as an object to be cleaned;
A pump device having a pump and a conduit for circulating the cleaning liquid in the cleaning tank;
The silicon wafer cleaning apparatus, wherein the microbubble generator is provided in a pipe line of the pump device.

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