JP5627560B2 - Fine particle production coating apparatus and fine particle coating method - Google Patents

Description

  The present invention relates to a fine particle production coating apparatus, a fine particle coating method, and a fine particle-containing thin film.

  In a conventional fine particle manufacturing apparatus, an oxide particle dispersion liquid containing oxide particles and a dispersion medium is brought into contact with single crystal silicon while ultrasonic waves are applied to the dispersion liquid to collide the oxide particles with single crystal silicon. Thus, at least a part of the single crystal silicon is pulverized to generate silicon fine particles (see, for example, Patent Document 1).

JP 2008-19115 (page 10, line 43 to page 11, line 7, FIG. 2)

  However, in the conventional fine particle manufacturing apparatus, single crystal silicon is placed in a container filled with an oxide particle dispersion containing oxide particles and a dispersion medium, and a predetermined interval from the single crystal silicon is placed. The horn part of the ultrasonic generator is set and ultrasonic processing is performed. Thus, the oxide particles pulverize a part of the single crystal silicon to generate silicon fine particles. However, normally, in such a state, since the generated silicon fine particles cannot be polished with ultrasonic waves a plurality of times, the shape of the silicon fine particles becomes distorted and cannot be made spherical. When the fine particles are used as a filler in an irregular shape, there are problems such as a problem of hindering the flow of the filler and a decrease in filling efficiency.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a fine particle production coating apparatus and a fine particle coating method capable of forming fine particles into a nearly spherical shape and applying fine particles to a desired position. Another object is to obtain a fine particle-containing thin film produced using such a fine particle production and coating apparatus.

In order to achieve the above object, a fine particle production coating apparatus according to the present invention includes a dispersion holding chamber that encloses a fine particle dispersion containing fine particles, an ultrasonic wave application unit that applies ultrasonic waves to the fine particle dispersion, A nozzle that discharges the fine particle dispersion from the dispersion holding chamber, and a reflective member that is detachably attached to the discharge port of the nozzle and is made of the same material as the fine particles. It has a reflecting structure so that a plurality of fine particle dispersions to which ultrasonic waves are applied by a sound wave applying means are reflected in the dispersion holding chamber.

  According to the present invention, since the dispersion holding chamber having a reflection structure is provided so that a plurality of fine particle dispersions to which ultrasonic waves are applied by the ultrasonic wave application means are reflected, the fine particles are polished by ultrasonic waves a plurality of times. As a result, spherical fine particles can be produced, and spherical fine particles can be applied to desired positions from a nozzle.

1 is a cross-sectional view showing a fine particle production and coating apparatus according to Embodiment 1 of the present invention. FIG. 2 is a diagram schematically illustrating a state during the coating process of the fine particle production coating apparatus according to the first embodiment. FIG. 3 is a cross-sectional view schematically showing an example of a fine particle mixed film produced by the fine particle production coating apparatus according to the first embodiment.

  Exemplary embodiments of a fine particle production and coating apparatus, a fine particle coating method, and a fine particle-containing thin film according to embodiments of the present invention will be explained below in detail with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments. Moreover, the cross-sectional view of the fine particle-containing thin film used in the following embodiments is a schematic one, and the relationship between the thickness and width of the layer, the ratio of the thickness of each layer, and the like may be different from the actual ones.

Embodiment 1 FIG.
1 is a cross-sectional view showing a fine particle production and coating apparatus according to Embodiment 1 of the present invention. The fine particle manufacturing and coating apparatus 10 holds a liquid 20 in which fine particles are dispersed (hereinafter referred to as a fine particle dispersion), and the fine particle dispersion is dispersed in a dispersion holding chamber 12 having a structure in which the fine particle dispersion 20 can be reflected by an ultrasonic wave 51. A nozzle 14 for discharging the liquid 20 is provided. An inlet (not shown) for injecting the fine particle dispersion 20 is provided on the lid member 13 side of the dispersion holding chamber 12.

  The dispersion liquid holding chamber 12 is formed by a space provided in the reflecting plate 11 and a lid member 13 that closes one opening of the space. The dispersion liquid holding chamber 12 confines the fine particle dispersion liquid 20, and the fine particles collide with other fine particles by the ultrasonic wave 51 applied to the fine particle dispersion liquid 20 or collide with the wall surface 121 constituting the dispersion liquid holding chamber 12. However, it may have a shape that is polished into a spherical shape. For example, a parabolic shape having a focal point in the vicinity of the discharge port of the nozzle 14, a conical shape, a truncated cone shape, a pyramid shape, a truncated pyramid shape, or the like can be used.

  The nozzle 14 is provided in the other opening of the dispersion liquid holding chamber 12 where the lid member 13 is not formed, and determines the discharge direction of the fine particle dispersion 20 when the fine particle dispersion 20 is discharged. The shape of the nozzle 14 is not particularly limited as long as the edge can be brought into contact with the liquid surface raised by the focusing of the ultrasonic wave, and is formed into a conical shape or a truncated cone shape that narrows toward the tip of the opening, or a slit shape. be able to. In this example, the nozzle 14 is provided so as to face upward in the vertical direction.

  An opening portion of the nozzle 14 (hereinafter referred to as a discharge port 141) is provided with a reflective plate 15 that covers the discharge port 141 and can be opened and closed. The reflector 15 can block the discharge port 141 of the nozzle 14 during the production of the fine particles, and the discharge port 141 of the nozzle 14 can be used to discharge the fine particle dispersion 20 to the discharge target after the production of the fine particles. The reflector 15 is opened so as to be exposed.

The dispersion liquid holding chamber 12 is provided with an ultrasonic wave generation unit that applies ultrasonic waves to the fine particle dispersion liquid 20 in the dispersion liquid holding room 12. The ultrasonic wave generator is provided on the surface of the lid member 13 on the side opposite to the dispersion liquid holding chamber 12, the drive electrode (not shown) provided on the upper surface of the piezoelectric element 16, and the lower surface of the piezoelectric element 16. A common electrode (not shown), and a driver (not shown) that is provided between the drive electrode and the common electrode and applies a high-frequency voltage between the drive electrode and the common electrode. The piezoelectric element 16 is made of a material that can efficiently generate ultrasonic waves. For example, PZT (Pb (Zr _x , Ti _1-x ) O ₃ ), lead titanate (PbTiO ₃ ), or the like is used. it can. By such an ultrasonic wave generator, a high frequency voltage based on a signal from the driver is applied to the drive electrode and the common electrode, the piezoelectric element 16 vibrates, and the ultrasonic wave 51 is applied to the fine particle dispersion 20 via the lid member 13. Is done.

  The lid member 13 is made of an insulating material so that the piezoelectric element 16 and the fine particle dispersion 20 can be insulated. The lid member 13 may be any insulating material that can transmit ultrasonic waves to the fine particle dispersion 20 with little loss, and may be a resin sheet such as a polyimide sheet, a ceramic such as a silicon oxide film or alumina, or the like. . The material is also selected depending on the type of fine particles to be produced. For example, when producing silicon fine particles, silicon fine particles with less impurity contamination can be produced by using as the lid member 13 made of a silicon oxide film.

  The fine particle dispersion 20 is obtained by dispersing fine particles in pure water, water, or an aqueous liquid (solvent). In order to avoid contamination of impurities as much as possible, it is desirable to use pure water as a solvent. However, when the purity requirement is not so strict, water or an aqueous liquid can be used as the solvent. The fine particles initially introduced into the fine particle dispersion 20 are fine particles applied to the object to be processed by the fine particle production / coating apparatus 10 and are finely pulverized in advance (for example, about 10 μm or less).

  In order to produce fine particles free from impurities, it is desirable that the materials of the reflectors 11 and 15 and the nozzle 14 be the same material as the fine particle material contained in the fine particle dispersion 20. By making these members the same material as the fine particles, when the fine particles are polished by the ultrasonic wave 51 to be spherical fine particles, the fine particles collide with the constituent members of the dispersion holding chamber 12 and newly become fine particles from the constituent members. However, since the same material is used, deterioration of the purity of the fine particle dispersion 20 can be suppressed. As materials constituting these constituent members and fine particles, Si (silicon), Ge (germanium), InGaAs (indium gallium arsenide), PbS (lead sulfide), SiC (silicon carbide), SiN (silicon nitride), etc. Can be used.

  Next, the fine particle production process and the fine particle application process in the fine particle production and coating apparatus 10 will be described. Here, as shown in FIG. 1, a case where the dispersion liquid holding chamber 12 is formed in a parabolic shape will be described as an example.

<Fine particle production process>
First, as shown in FIG. 1, in a state where the discharge port 141 of the nozzle 14 is covered with the reflection plate 15, the fine particle dispersion 20 is supplied from the injection port (not shown) provided near the lid member 13. Inject and refill inside. The injection amount is desirably such that the fine particle dispersion 20 is in contact with at least the nozzle 14 in a state where the ultrasonic wave 51 is irradiated. For this purpose, it is only necessary that the fine particle dispersion 20 is injected and replenished to the extent that the fine particle dispersion 20 comes into contact with the nozzle 14 in a state where the ultrasonic wave 51 is not irradiated.

  Further, the fine particle dispersion 20 has fine particles to be coated on a processing target in a subsequent fine particle coating process. Si, Ge, InGaAs, PbS, SiC, SiN, etc. can be used as the material of the fine particles. Further, the size of the fine particles in the fine particle dispersion 20 to be initially charged should be smaller than the size of the dispersion holding chamber 12, but is desirably about 10 μm or less. This is because if the fine particles are larger than 10 μm, they may sink immediately in the liquid, and polishing with the ultrasonic wave 51 becomes difficult. In order to finally produce high-purity fine particles free from impurities, it is desirable to increase the purity of the fine particles initially introduced into the fine particle dispersion 20. The fine particles introduced at this time do not have to be spherical, and may have an irregular shape.

  After the fine particle dispersion 20 is injected and replenished into the dispersion holding chamber 12, the piezoelectric element 16 is driven, and an ultrasonic wave 51 is applied to the fine particle dispersion 20 through the lid member 13. As a result, the ultrasonic wave 51 propagates through the fine particle dispersion 20, is reflected by the side wall 121 constituting the dispersion holding chamber 12, and is focused on the focal point F. Since the focal point F includes the nozzle 14 and the reflection plate 15 is provided so as to block the nozzle 14, the ultrasonic wave 51 is reflected at the position of the nozzle 14 and the reflection plate 15. Also, the particles in the fine particle dispersion 20 receive the energy from the ultrasonic wave 51 and are reflected by the reflectors 11 and 15 and the nozzle 14 in the same manner as the fine particle dispersion 20, and are enclosed in the dispersion holding chamber 12. The fine particles are polished a plurality of times by the collision of the fine particles in the dispersion liquid 20 or the collision with the wall surface 121, and the fine particles having an irregular shape at the time of charging become spherical or nearly spherical.

  In this ultrasonic polishing, the polishing time varies depending on the shape of the fine particles to be initially introduced, but the spherical accuracy is improved by polishing for a long time. For example, substantially spherical fine particles can be obtained by setting the polishing time to about several minutes to several tens of minutes. Further, by increasing the size of the piezoelectric element 16 and the reflecting plate 11, the ultrasonic wave 51 can be converged more greatly, so that the time required to make the same spherical shape is shortened.

  In the above-described example, the reflection plate 15 that covers the discharge port 141 of the nozzle 14 is provided so that the fine particles are efficiently reflected so that spherical fine particles are easily formed. However, when the ultrasonic wave 51 having such an intensity that the mist is not discharged from the nozzle 14 is applied to the fine particle dispersion 20, the fine particles are reflected by the nozzle 14 and can be polished a plurality of times. It does not have to be provided.

  The shape of the dispersion holding chamber 12 is a paraboloid shape and has a focal point F. As described above, when viewed as a fine particle production apparatus, it is desirable in terms of efficiency to provide the installation location of the discharge port 141 of the nozzle 14 at the position of the focal point F, but also when viewed as a coating apparatus, the efficiency of discharge Therefore, it is desirable to install the discharge port 141 of the nozzle 14 at the position of the focal point F. However, even if the position of the focal point F is not this position, it is possible to produce spherical fine particles, so that the position may be an arbitrary position.

  As described above, by producing spherical fine particles, it is possible to obtain a filler for a semiconductor encapsulating material and various resin fillers that make it difficult to damage a contact object and has high fluidity and filling properties.

<Particle coating treatment>
Next, a fine particle coating process in which the fine particle dispersion 20 is applied to a desired position on the processing target after the above-described fine particle manufacturing process is performed will be described. FIG. 2 is a diagram schematically illustrating a state during the coating process of the fine particle production coating apparatus according to the first embodiment. Here, a substrate stage 31 for holding a substrate 32 as a processing target is provided above the fine particle production coating apparatus 10. Further, since the nozzle 14 of the fine particle production coating apparatus 10 faces vertically upward, the substrate 32 is held by a substrate holding mechanism such as an electrostatic chuck mechanism or a vacuum chuck mechanism so as to face the nozzle 14. Then, the reflecting plate 15 provided so as to cover the discharge port 141 of the nozzle 14 is removed.

  Next, after the substrate stage 31 is driven to the position where the fine particles are applied to align the substrate 32 and the discharge port 141 of the nozzle 14, the piezoelectric element 16 is driven. Also in this case, the ultrasonic wave 51 generated from the piezoelectric element 16 is reflected by the wall surface 121 and focused on the focal point F. Since the nozzle 14 is at the focal point, the ultrasonic wave 51 is further densified, a surface traveling wave is generated from the end of the nozzle 14, a droplet is separated from the wave head, and is discharged as a mist 21 containing fine particles. Thus, at the time of applying fine particles, the fine particle production coating device 10 functions as a mist jet discharge head.

  At this time, in order to prevent the fine particle dispersion 20 from overflowing from the nozzle 14, it is desirable that the piezoelectric element 16 be driven in a burst manner. Although it differs depending on the size of the reflecting plate 11 constituting the dispersion holding chamber 12, for example, the driving voltage of the piezoelectric element 16 is set to about several tens of volts, the burst frequency is set to several MHz, and the discharge interval is set to several tens of kHz. It becomes possible to discharge. In order to increase the discharge amount, the drive voltage is increased, the wave number is increased, the burst frequency is increased, or the duty ratio (ratio of drive signal input time to unit time) is increased. . However, when the ultrasonic wave 51 is applied at a high duty ratio, the liquid pressure reaches the limit pressure for holding the meniscus by the radiation pressure at a voltage lower than the voltage at which mist starts to be discharged, and the liquid may overflow to the surface of the nozzle 14. Therefore, it is desirable that the conditions do not become such.

  Further, the sharper the tip of the opening of the nozzle 14, the more easily the surface traveling wave is generated, and the mist is more easily discharged. For example, when producing Si fine particles, if a discharge substrate 141 (opening) is produced by anisotropic wet etching or the like using a Si substrate having a (100) plane as a constituent member of the nozzle 14, The opening has a very acute angle, and a good discharge result can be obtained. The constituent material of the nozzle 14 is not limited to Si, and other materials can be used as long as the opening can be made an acute angle.

  The fine particle dispersion 20 discharged from the nozzle 14 is applied to a position on the substrate 32 facing the discharge port 141 of the nozzle 14, and the Si fine particles 22 are arranged on the substrate 32. Then, by moving the substrate stage 31 in a predetermined direction by a moving mechanism (not shown), it is possible to apply spherical fine particles to a desired position. And after application | coating is complete | finished, the reflecting plate 15 is arrange | positioned so that the opening of the nozzle 14 may be plugged up. Further, when the amount of the fine particle dispersion 20 becomes equal to or less than a predetermined value, the fine particle dispersion 20 is replenished and the fine particle production process is performed as described in the fine particle production process.

  In this example, since the mist jet head is installed upward (opposite to gravity), large fine particles immediately settle on the piezoelectric element 16 side. Therefore, discharge of large fine particles can be suppressed. That is, only fine particles having a desired size or less can be discharged. The maximum particle size to be ejected can also be changed by changing the specific gravity of the solvent simultaneously with the fine particles. In the above description, the substrate stage 31 is moved, but the fine particle production coating apparatus 10 may be moved by a driving mechanism.

  According to the first embodiment, the fine particle dispersion 20 in which irregularly shaped fine particles are dispersed in a solvent is sealed in the dispersion holding chamber 12 which is a closed space, and an ultrasonic wave 51 is applied so that the fine particles are separated from each other. Since the particles are caused to collide with each other or the fine particles are caused to collide with the wall surface 121 constituting the dispersion holding chamber 12, the fine particles can be made spherical or nearly spherical. Further, since the fine particles having a spherical shape or a shape close to a spherical shape are ejected from the dispersion liquid holding chamber 12, the fine particles having a spherical shape or a shape close to a spherical shape can be applied to a desired position. Furthermore, since only the resin can be injected after the filler for the semiconductor encapsulant is applied at a desired position, not only can the ratio of the filler be easily adjusted, but also the waste of material can be reduced. Also have.

Embodiment 2. FIG.
FIG. 3 is a cross-sectional view schematically showing an example of a fine particle mixed film produced by the fine particle production coating apparatus of the first embodiment. Here, the Si fine particle mixed film in which the amorphous Si layer 23 is formed so as to cover the single-layer Si fine particles 22 arranged on the substrate 32 is illustrated.

  A method for producing such a Si fine particle mixed film will be described. First, the spherical crystalline Si fine particles 22 are polished by the fine particle production coating apparatus 10 according to the fine particle production process shown in the first embodiment until the size becomes from about [mu] m to several [mu] m, and the corners of the fine particles are rounded into a spherical shape. To do. Thereafter, the application shown in the fine particle application process of Embodiment 1 is performed so that the fine particles do not overlap or aggregate. After the coating, if necessary, the surface treatment of the coated Si fine particles 22 is performed, and then an amorphous Si layer 23 is formed by a method such as a plasma CVD (Plasma Chemical Vapor Deposition) method.

  According to the Si fine particle mixed film having such a configuration, not only the wavelength at which the amorphous Si layer 23 absorbs but also the wavelength at which crystalline Si absorbs can be used. Although the Si fine particles 22 have been described here, a fine particle mixed film using other fine particles can be formed in the same manner. For example, instead of the Si fine particles 22, fine particles such as Ge may be used. If an amorphous Si layer is formed after applying the Ge fine particles, not only the wavelength at which the amorphous Si layer absorbs but also the light on the longer wavelength side of Ge can be absorbed. Such a fine particle mixed film can be used for, for example, a solar battery.

  According to the second embodiment, the fine particle mixed film including the fine particles applied in a spherical shape with a very high purity is hardly mixed with impurities. Further, since the fine particles can be applied without increasing the impurities, the functional film constituted by the fine particle mixed film can exhibit two functions resulting from the fine particles and the film formation. Further, when the Si fine particles 22 are used as the fine particles, since the Si fine particles 22 are spherical, a fine particle mixed film can be easily produced by subsequent surface treatment or film formation of the amorphous Si layer 23 to increase light absorption. You can also Moreover, unlike the microcrystalline Si film formed only in the gas phase, the size of the crystalline Si fine particles 22 can be increased from sub-μm to several μm, so that the light absorbance can be further increased. Has an effect.

DESCRIPTION OF SYMBOLS 10 Fine particle production application apparatus 11,15 Reflector plate 12 Dispersion holding chamber 13 Cover member 14 Nozzle 16 Piezoelectric element 20 Fine particle dispersion 21 Mist 22 Si fine particle 23 Amorphous Si layer 31 Substrate stage 32 Substrate 51 Ultrasonic 121 Wall surface 141 Discharge port

Claims (7)

A dispersion holding chamber for enclosing a fine particle dispersion containing fine particles;
Ultrasonic application means for applying ultrasonic waves to the fine particle dispersion;
A nozzle for discharging the fine particle dispersion from the dispersion holding chamber;
A reflective member made of the same material as the fine particles, detachably attached to the discharge port of the nozzle;
With
The dispersion liquid holding chamber has a reflection structure so that a plurality of the fine particle dispersion liquids to which ultrasonic waves are applied by the ultrasonic wave application means are reflected in the dispersion liquid holding chamber.   The fine particle manufacturing and coating apparatus according to claim 1, wherein the dispersion holding chamber is made of the same material as the fine particles. The dispersion retention chamber, producing fine particles coating apparatus according to claim 1 or 2, characterized in that it has a parabolic shape. The fine particle manufacturing and coating apparatus according to claim 3 , wherein the parabolic dispersion holding chamber has a focal point at the position of the nozzle. The fine particle manufacturing and coating apparatus according to any one of claims 1 to 4 , wherein the nozzle is disposed such that a discharge port is vertically upward. The ultrasonic wave application means includes
A piezoelectric element provided on the outside of the wall constituting the dispersion holding chamber;
Voltage applying means for applying a high-frequency voltage to the piezoelectric element;
The fine particle production coating apparatus according to any one of claims 1 to 5 , further comprising: A dispersion holding chamber for enclosing a fine particle dispersion containing fine particles;
Ultrasonic application means for applying ultrasonic waves to the fine particle dispersion;
A nozzle for discharging the fine particle dispersion from the dispersion holding chamber;
A fine particle coating method in a fine particle production coating apparatus comprising:
Injecting the fine particle dispersion into the dispersion holding chamber;
The ultrasonic wave is applied to the fine particle dispersion by the ultrasonic wave application unit under the condition that the fine particle dispersion is not discharged from the nozzle, and the fine particles collide with the other fine particles or the wall surface of the dispersion holding chamber for polishing. Process,
Applying the fine particle dispersion to a processing target by applying ultrasonic waves to the fine particle dispersion under a condition that the fine particle dispersion containing the polished fine particles is discharged as mist from the nozzle;
A fine particle coating method comprising:

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